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in this work, we introduce a fast implementation of the minimum - weight perfect matching ( mwpm ) decoder, the most widely used decoder for several important families of quantum error correcting codes, including surface codes. our algorithm, which we call sparse blossom, is a variant of the blossom algorithm which directly solves the decoding problem relevant to quantum error correction. sparse blossom avoids the need for all - to - all dijkstra searches, common amongst mwpm decoder implementations. for 0. 1 % circuit - level depolarising noise, sparse blossom processes syndrome data in both $ x $ and $ z $ bases of distance - 17 surface code circuits in less than one microsecond per round of syndrome extraction on a single core, which matches the rate at which syndrome data is generated by superconducting quantum computers. our implementation is open - source, and has been released in version 2 of the pymatching library.
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arxiv:2303.15933
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in this paper, we consider the problems of approximating uncertainties and feedback control for a class of nonlinear systems without full - known states, and two approximation methods are proposed : universal approximation using integral - chain differentiator or extended observer. comparing to the approximations by fuzzy system and radial - based - function ( rbf ) neural networks, the presented two methods can not only approximate universally the uncertainties, but also estimate the unknown states. moreover, the integral - chain differentiator can restrain noises thoroughly. the theoretical results are confirmed by computer simulations for feedback control.
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arxiv:1102.2794
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##dom by of websites devoted to science fiction and related genres for all media. the first science fiction fanzine, the comet, was published in 1930 by the science correspondence club in chicago, illinois. one of the best known fanzines today is ansible, edited by david langford, winner of numerous hugo awards. other notable fanzines to win one or more hugo awards include file 770, mimosa, and plokta. artists working for fanzines have frequently risen to prominence in the field, including brad w. foster, teddy harvia, and joe mayhew ; the hugos include a category for best fan artists. = = elements = = science fiction elements can include, among others : temporal settings in the future, or in alternative histories ; predicted or speculative technology such as brain - computer interface, bio - engineering, superintelligent computers, robots, ray guns, and other advanced weapons ; space travel, settings in outer space, on other worlds, in subterranean earth, or in parallel universes ; fictional concepts in biology such as aliens, mutants, and enhanced humans ; undiscovered scientific possibilities such as teleportation, time travel, and faster - than - light travel or communication ; new and different political and social systems and situations, including utopian, dystopian, post - apocalyptic, or post - scarcity ; future history and speculative evolution of humans on earth or on other planets ; paranormal abilities such as mind control, telepathy, and telekinesis. = = international examples = = = = subgenres = = = = related genres = = = = see also = = = = references = = = = general and cited sources = = = = external links = = science fiction bookshelf at project gutenberg science fiction fanzines ( current and historical ) online sfwa " suggested reading " list science fiction at standardebooks. org science fiction research association a selection of articles written by mike ashley, iain sinclair and others, exploring 19th - century visions of the future. archived 18 june 2023 at the wayback machine from the british library ' s discovering literature website. merril collection of science fiction, speculation and fantasy at toronto public library science fiction studies ' chronological bibliography of science fiction history, theory, and criticism best 50 sci - fi novels of all time ( esquire ; 21 march 2022 )
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https://en.wikipedia.org/wiki/Science_fiction
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if l is a tonelli lagrangian defined on the tangent bundle of a compact and connected manifold whose dimension is at least 2, we associate to l the tiered aubry set and the tiered mane set ( defined in the article ). we prove that the tiered mane set is closed, connected, chain transitive and that if l is generic in the mane sense, the tiered mane set has no interior. then, we give an example of such an explicit generic tonelli lagrangian function and an example proving that when m is the torus, the closure of the tiered aubry set and the closure of the union of the k. a. m. tori may be different.
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arxiv:0803.0626
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consider a matroid $ m $ whose ground set is equipped with a labeling to an abelian group. a basis of $ m $ is called $ f $ - avoiding if the sum of the labels of its elements is not in a forbidden label set $ f $. h \ " orsch, imolay, mizutani, oki, and schwarcz ( 2024 ) conjectured that if an $ f $ - avoiding basis exists, then any basis can be transformed into an $ f $ - avoiding basis by exchanging at most $ | f | $ elements. this proximity conjecture is known to hold for certain specific groups ; in the case where $ | f | \ le 2 $ ; or when the matroid is subsequence - interchangeably base orderable ( sibo ), which is a weakening of the so - called strongly base orderable ( sbo ) property. in this paper, we settle the proximity conjecture for sparse paving matroids or in the case where $ | f | \ le 4 $. related to the latter result, we present the first known example of a non - sibo matroid. we further address the setting of multiple group - label constraints, showing proximity results for the cases of two labelings, sibo matroids, matroids representable over a fixed, finite field, and sparse paving matroids.
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arxiv:2411.06771
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in this paper, we consider symbol - level precoding ( slp ) in channel - coded multiuser multi - input single - output ( miso ) systems. it is observed that the received slp signals do not always follow gaussian distribution, rendering the conventional soft demodulation with the gaussian assumption unsuitable for the coded slp systems. it, therefore, calls for novel soft demodulator designs for non - gaussian distributed slp signals with accurate log - likelihood ratio ( llr ) calculation. to this end, we first investigate the non - gaussian characteristics of both phase - shift keying ( psk ) and quadrature amplitude modulation ( qam ) received signals with existing slp schemes and categorize the signals into two distinct types. the first type exhibits an approximate - gaussian distribution with the outliers extending along the constructive interference region ( cir ). in contrast, the second type follows some distribution that significantly deviates from the gaussian distribution. to obtain accurate llr, we propose the modified gaussian soft demodulator and gaussian mixture model ( gmm ) soft demodulators to deal with two types of signals respectively. subsequently, to further reduce the computational complexity and pilot overhead, we put forward a novel neural soft demodulator, named pilot feature extraction network ( pfen ), leveraging the transformer mechanism in deep learning. simulation results show that the proposed soft demodulators dramatically improve the throughput of existing slps for both psk and qam transmission in coded systems.
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arxiv:2310.10296
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evaluation of generative models is mostly based on the comparison between the estimated distribution and the ground truth distribution in a certain feature space. to embed samples into informative features, previous works often use convolutional neural networks optimized for classification, which is criticized by recent studies. therefore, various feature spaces have been explored to discover alternatives. among them, a surprising approach is to use a randomly initialized neural network for feature embedding. however, the fundamental basis to employ the random features has not been sufficiently justified. in this paper, we rigorously investigate the feature space of models with random weights in comparison to that of trained models. furthermore, we provide an empirical evidence to choose networks for random features to obtain consistent and reliable results. our results indicate that the features from random networks can evaluate generative models well similarly to those from trained networks, and furthermore, the two types of features can be used together in a complementary way.
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arxiv:2208.09218
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in this work we study the intrinsic geometry of the space of kahler metrics under various riemannian metrics. the first part is on the dirichlet metric. we motivate its study, we compute its curvature, and we make links with the calabi metric, the k - energy, the degenerate complex hessian equation. the second part is on the weighted metrics, for which we investigate as well their geometric properties.
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arxiv:1202.6610
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hyper - partisan misinformation has become a major public concern. in order to examine what type of misinformation label can mitigate hyper - partisan misinformation sharing on social media, we conducted a 4 ( label type : algorithm, community, third - party fact - checker, and no label ) x 2 ( post ideology : liberal vs. conservative ) between - subjects online experiment ( n = 1, 677 ) in the context of covid - 19 health information. the results suggest that for liberal users, all labels reduced the perceived accuracy and believability of fake posts regardless of the posts ' ideology. in contrast, for conservative users, the efficacy of the labels depended on whether the posts were ideologically consistent : algorithmic labels were more effective in reducing the perceived accuracy and believability of fake conservative posts compared to community labels, whereas all labels were effective in reducing their belief in liberal posts. our results shed light on the differing effects of various misinformation labels dependent on people ' s political ideology.
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arxiv:2203.00710
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in their interactions ) and kenny later published his work on models of non - independence in dyadic research in 1996. with a growing interest in marriage and family therapy in relationship science, in the late 1980s and 1990s, researchers such as howard markman, frank floyd, and scott stanley began developing romantic relationship ( with a primary focus on marriages ) interventions ; specifically, in 1995, floyd and colleagues published the program they developed, called prevention intervention and relationship enhancement ( prep ). interest in and development of relationship education programming increased in the 2000s due to state and federal healthy marriage initiatives, which allocated grant funding to support programming that would impact disadvantaged communities. although there were many theoretical and empirical contributions of the 1970s and 80s, the professional evolution of relationship science was simultaneously taking place. the first international conference specifically dedicated to relationship processes took place in 1977 in swansea, wales, hosted by mark cook ( a social psychologist ) and glen wilson ( a psychotherapist ). in 1982, the first of the eventually bi - annual international conference of personal relationships ( icpr ) took place in madison, wisconsin, under the direction of robin gilmour and steve duck, with about 100 attendees. two years later, in 1984, the international society for the study of personal relationships ( isspr ) was borne out of the icpr and the journal of social and personal relationships, the first peer - reviewed journal unique to the field of relationship science, was established. then in 1987, the iowa network of personal relationships ( which would later be known as the international network of personal relationships ; inpr ) was formed and hal kelley was elected president of isspr that same year. a few years later in 1991, ellen berscheid ( the then - president of isspr ) announced a merger of isspr and inpr, which ultimately fell through until the idea was reignited over a decade later. in 1994, the journal personal relationships was formally established by isspr and began publishing work in relationship science with pat noller as the editor ; anne peplau became president of isspr. the changing of roles only persisted when dan perlman became president of isspr in 1996 and began discussing with the president of inpr ( at the time, barbara sarason ) how they might work to better integrate the efforts and goals of the two organizations ; in 1998, jeffry simpson took over as editor of personal relationships. the decades - long, interdisciplinary study of relationships culminated in ellen berscheid ' s 1999 article " the greening of relationship science ". here, bersche
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https://en.wikipedia.org/wiki/Relationship_science
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[ abridged ] the nature and evolutionary properties of the faint radio population, responsible for the steepening observed in the 1. 4 ghz source counts below 1 millijy, are not yet entirely clear. radio spectral indices may help to constrain the origin of the radio emission in such faint radio sources and may be fundamental in understanding eventual links to the optical light. we study the spectral index behaviour of sources that were found in the 1. 4 ghz atesp survey ( prandoni et al. 2000a, b ). using the australia telescope compact array we observed at 5 ghz part of the region covered by the sub - mjy atesp survey. in particular we imaged a one square degree area for which deep optical imaging in ubvrijk is available. in this paper we present the 5 ghz survey and source catalogue, we derive the 5 ghz source counts and we discuss the 1. 4 - 5 ghz spectral index properties of the atesp sources. the analysis of the optical properties of the sample will be the subject of a following paper. the 5 ghz survey has produced a catalogue of 111 radio sources, complete down to a ( 6 sigma ) limit s _ lim ( 5 ghz ) ~ 0. 4 mjy. we take advantage of the better spatial resolution at 5 ghz ( ~ 2 arcsec compared to ~ 8 arcsec at 1. 4 ghz ) to infer radio source structures and sizes. the 5 ghz source counts derived by the present sample are consistent with those reported in the literature, but improve significantly the statistics in the flux range 0. 4 < s ( 5 ghz ) < 1 mjy. the atesp sources show a flattening of the 1. 4 - 5 ghz spectral index with decreasing flux density, which is particularly significant for the 5 ghz selected sample. such a flattening confirm previous results coming from smaller samples and is consistent with a flattening of the 5 ghz source counts occurring at fluxes < = 0. 5 mjy.
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arxiv:astro-ph/0607141
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aims : we aim at detecting h $ _ 2 $ o in the atmosphere of the hot jupiter hd 209458 b and perform a multi - band study in the near infrared with carmenes. methods : the h $ _ 2 $ o absorption lines from the planet ' s atmosphere are doppler - shifted due to the large change in its radial velocity during transit. this shift is of the order of tens of km s $ ^ { - 1 } $, whilst the earth ' s telluric and the stellar lines can be considered quasi - static. we took advantage of this to remove the telluric and stellar lines using sysrem, a principal component analysis algorithm. the residual spectra contain the signal from thousands of planetary molecular lines well below the noise level. we retrieve this information by cross - correlating the spectra with models of the atmospheric absorption. results : we find evidence of h $ _ 2 $ o in hd 209458 b with a signal - to - noise ratio ( s / n ) of 6. 4. the signal is blueshifted by - - 5. 2 $ ^ { + 2. 6 } _ { - 1. 3 } $ km s $ ^ { - 1 } $, which, despite the error bars, is a firm indication of day - to - night winds at the terminator of this hot jupiter. additionally, we performed a multi - band study for the detection of h $ _ 2 $ o individually from the three nir bands covered by carmenes. we detect h $ _ 2 $ o from its 1. 0 $ \ mu $ m band with a s / n of 5. 8, and also find hints from the 1. 15 $ \ mu $ m band, with a low s / n of 2. 8. no clear planetary signal is found from the 1. 4 $ \ mu $ m band. conclusions : our significant signal from the 1. 0 $ \ mu $ m band in hd 209458 b represents the first detection of h $ _ 2 $ o from this band, the bluest one to date. the unfavorable observational conditions might be the reason for the inconclusive detection from the stronger 1. 15 and 1. 4 $ \ mu $ m bands. h $ _ 2 $ o is detected from the 1. 0 $ \ mu $ m band in hd 209458 b, but hardly in hd 189733 b, which supports a stronger aerosol extinction in the latter.
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arxiv:1908.08754
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we examine the transverse and longitudinal components of the drag force upon a straight vortex line due to the scattering of liquid $ ^ 4 $ he excitations. for this purpose, we consider a recently proposed hamiltonian that describes the dissipative motion of a vortex, giving an explicit expression for the vortex - quasiparticle interaction. the involved dissipative coefficients are obtained in terms of the reservoir correlation function. most of our explicit calculations are concerned to the range of temperatures below 0. 4 k, at which the reservoir is composed by phonon quasiparticle excitations. we also discuss some important implications in the determination of possible scattering processes leading to dissipation, according to the values of vortex mass found in the literature.
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arxiv:cond-mat/9811381
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the low - $ q ^ 2 $ nucleon structure is given with a simple nonperturbative input of three valence quarks and an all - order infrared - safe evolution scheme, showing some consistences with the experimental data. the resonance peaks in the experimental data of $ f _ 2 $ structure function are found to be modulated by the valence quark distributions. with little sea quark distribution at low $ q ^ 2 $ the valence - quark bump is clearly shown in the structure function. the three valence quark distributions at the hadronic scale is found to be the dominant origin of the pdfs at the hard scales. the high - twist corrections are needed to explain the sizeable discrepancy between the theory and the experimental measurements at low $ q ^ 2 $. the infrared - safe evolution scheme is a powerful tool for connecting the nucleon structures in the nonperturbative and perturbative regions.
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arxiv:2410.00468
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we consider a nonlocal isoperimetric problem defined in the whole space $ \ r ^ n $, whose nonlocal part is given by a riesz potential with exponent $ \ alpha \ in ( 0, n - 1 ) $. we show that critical configurations with positive second variation are local minimizers and satisfy a quantitative inequality with respect to the $ l ^ 1 $ - norm. this criterion provides the existence of a ( explicitly determined ) critical threshold determining the interval of volumes for which the ball is a local minimizer, and allows to address several global minimality issues.
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arxiv:1307.5269
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we obtain the ground state magnetization of the heisenberg and xxz spin chains in a magnetic field $ h $ as a series in $ \ sqrt { h _ c - h } $, where $ h _ c $ is the smallest field for which the ground state is fully polarized. all the coefficients of the series can be computed in closed form through a recurrence formula that involves only algebraic manipulations. the radius of convergence of the series in the full range $ 0 < h \ leq h _ c $ is studied numerically. to that end we express the free energy at mean magnetization per site $ - 1 / 2 \ leq \ langle \ sigma ^ z _ i \ rangle \ leq 1 / 2 $ as a series in $ 1 / 2 - \ langle \ sigma ^ z _ i \ rangle $ whose coefficients can be similarly recursively computed in closed form. this series converges for all $ 0 \ leq \ langle \ sigma ^ z _ i \ rangle \ leq 1 / 2 $. the recurrence is nothing but the bethe equations when their roots are written as a double series in their corresponding bethe number and in $ 1 / 2 - \ langle \ sigma ^ z _ i \ rangle $. it can also be used to derive the corrections in finite size, that correspond to the spectrum of a free compactified boson whose radius can be expanded as a similar series. the method presumably applies to a large class of models : it also successfully applies to a case where the bethe roots lie on a curve in the complex plane.
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arxiv:1901.05878
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quantum coherence is one of the most important resources in quantum information. indeed, preventing the loss of coherence is one of the most important technical challenges obstructing the development of large - scale quantum computers. recently, there has been substantial progress in developing mathematical resource theories of coherence, paving the way towards its quantification and control. to date however, these resource theories have only been mathematically formalised within the realms of convex - geometry, information theory, and linear algebra. this approach is limited in scope, and makes it difficult to go beyond resource theories of coherence for single system quantum states. in this paper we take a complementary perspective, showing that resource theories of coherence can instead be defined purely compositionally, that is, working with the mathematics of process theories, string diagrams and category theory. this new perspective offers several advantages : i ) it unifies various existing approaches to the study of coherence, for example, subsuming both speakable and unspeakable coherence ; ii ) it provides a general treatment of the compositional multi - system setting ; iii ) it generalises immediately to the case of quantum channels, measurements, instruments, and beyond ; iv ) it can easily be generalised to the setting where there are multiple distinct sources of decoherence ; and, iv ) it directly extends to arbitrary process theories, for example, generalised probabilistic theories and spekkens toy model - - providing the ability to operationally characterise coherence rather than relying on specific mathematical features of quantum theory for its description. more importantly, by providing a new, complementary, perspective on the resource of coherence, this work opens the door to the development of novel tools which would not be accessible from the linear algebraic mind set.
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arxiv:1911.04513
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after extending the regge - teitelboim formulation of gravity to include the case where the background embedding space is not flat, we examine the dynamics of the four - dimensional $ k = 0 $ robertson - walker ( rw ) manifold embedded in various five - dimensional backgrounds. we find that when the background is five - dimensional de sitter space, the rw manifold undergoes a transition from a de - accelerating phase to an accelerating phase. this occurs before the inclusion of matter, radiation or cosmological constant sources, and thus does not require a balance of different components. we obtain a reasonable two - parameter fit of this model to the hubble parameter data.
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arxiv:2206.14300
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we analyze an interacting particle system with a markov evolution of birth - and - death type. we have shown that a local competition mechanism ( realized via a density dependent mortality ) leads to a globally regular behavior of the population in course of the stochastic evolution.
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arxiv:0803.3565
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co - training is a popular semi - supervised learning framework to utilize a large amount of unlabeled data in addition to a small labeled set. co - training methods exploit predicted labels on the unlabeled data and select samples based on prediction confidence to augment the training. however, the selection of samples in existing co - training methods is based on a predetermined policy, which ignores the sampling bias between the unlabeled and the labeled subsets, and fails to explore the data space. in this paper, we propose a novel method, reinforced co - training, to select high - quality unlabeled samples to better co - train on. more specifically, our approach uses q - learning to learn a data selection policy with a small labeled dataset, and then exploits this policy to train the co - training classifiers automatically. experimental results on clickbait detection and generic text classification tasks demonstrate that our proposed method can obtain more accurate text classification results.
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arxiv:1804.06035
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diabetic retinopathy ( dr ) is a diabetes complication that affects eyes. dr is a primary cause of blindness in working - age people and it is estimated that 3 to 4 million people with diabetes are blinded by dr every year worldwide. early diagnosis have been considered an effective way to mitigate such problem. the ultimate goal of our research is to develop novel machine learning techniques to analyze the dr images generated by the fundus camera for automatically dr diagnosis. in this paper, we focus on identifying small lesions on dr fundus images. the results from our analysis, which include the lesion category and their exact locations in the image, can be used to facilitate the determination of dr severity ( indicated by dr stages ). different from traditional object detection for natural images, lesion detection for fundus images have unique challenges. specifically, the size of a lesion instance is usually very small, compared with the original resolution of the fundus images, making them diffcult to be detected. we analyze the lesion - vs - image scale carefully and propose a large - size feature pyramid network ( lfpn ) to preserve more image details for mini lesion instance detection. our method includes an effective region proposal strategy to increase the sensitivity. the experimental results show that our proposed method is superior to the original feature pyramid network ( fpn ) method and faster rcnn.
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arxiv:1911.08588
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it is a widely accepted fact that state - sponsored twitter accounts operated during the 2016 us presidential election spreading millions of tweets with misinformation and inflammatory political content. whether these social media campaigns of the so - called " troll " accounts were able to manipulate public opinion is still in question. here we aim to quantify the influence of troll accounts and the impact they had on twitter by analyzing 152. 5 million tweets from 9. 9 million users, including 822 troll accounts. the data collected during the us election campaign, contain original troll tweets before they were deleted by twitter. from these data, we constructed a very large interaction graph ; a directed graph of 9. 3 million nodes and 169. 9 million edges. recently, twitter released datasets on the misinformation campaigns of 8, 275 state - sponsored accounts linked to russia, iran and venezuela as part of the investigation on the foreign interference in the 2016 us election. these data serve as ground - truth identifier of troll users in our dataset. using graph analysis techniques we qualify the diffusion cascades of web and media context that have been shared by the troll accounts. we present strong evidence that authentic users were the source of the viral cascades. although the trolls were participating in the viral cascades, they did not have a leading role in them and only four troll accounts were truly influential.
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arxiv:1910.00531
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we present a framework for learning an efficient holistic representation for handwritten word images. the proposed method uses a deep convolutional neural network with traditional classification loss. the major strengths of our work lie in : ( i ) the efficient usage of synthetic data to pre - train a deep network, ( ii ) an adapted version of the resnet - 34 architecture with the region of interest pooling ( referred to as hwnet v2 ) which learns discriminative features for variable sized word images, and ( iii ) a realistic augmentation of training data with multiple scales and distortions which mimics the natural process of handwriting. we further investigate the process of transfer learning to reduce the domain gap between synthetic and real domain, and also analyze the invariances learned at different layers of the network using visualization techniques proposed in the literature. our representation leads to a state - of - the - art word spotting performance on standard handwritten datasets and historical manuscripts in different languages with minimal representation size. on the challenging iam dataset, our method is first to report an map of around 0. 90 for word spotting with a representation size of just 32 dimensions. furthermore, we also present results on printed document datasets in english and indic scripts which validates the generic nature of the proposed framework for learning word image representation.
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arxiv:1802.06194
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arcons, the array camera for optical to near - infrared spectrophotometry, was recently commissioned at the coude focus of the 200 - inch hale telescope at the palomar observatory. at the heart of this unique instrument is a 1024 - pixel microwave kinetic inductance detector ( mkid ), exploiting the kinetic inductance effect to measure the energy of the incoming photon to better than several percent. the ground - breaking instrument is lens - coupled with a pixel scale of 0. 23 " / pixel, with each pixel recording the arrival time ( < 2 microsec ) and energy of a photon ( ~ 10 % ) in the optical to near - ir ( 0. 4 - 1. 1 microns ) range. the scientific objectives of the instrument include the rapid follow - up and classification of the transient phenomena.
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arxiv:1201.5904
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in wireless communication systems, the nonlinear effect and inefficiency of power amplifier ( pa ) have posed practical challenges for system designs to achieve high spectral efficiency ( se ) and energy efficiency ( ee ). in this paper, we analyze the impact of pa on the se - ee tradeoff of orthogonal frequency division multiplex ( ofdm ) systems. an ideal pa that is always linear and incurs no additional power consumption can be shown to yield a decreasing convex function in the se - ee tradeoff. in contrast, we show that a practical pa has an se - ee tradeoff that has a turning point and decreases sharply after its maximum ee point. in other words, the pareto - optimal tradeoff boundary of the se - ee curve is very narrow. a wide range of se - ee tradeoff, however, is desired for future wireless communications that have dynamic demand depending on the traffic loads, channel conditions, and system applications, e. g., high - se - with - low - ee for rate - limited systems and high - ee - with - low - se for energy - limited systems. for the se - ee tradeoff improvement, we propose a pa switching ( pas ) technique. in a pas transmitter, one or more pas are switched on intermittently to maximize the ee and deliver an overall required se. as a consequence, a high ee over a wide range se can be achieved, which is verified by numerical evaluations : with 15 % se reduction for low se demand, the pas between a low power pa and a high power pa can improve ee by 323 %, while a single high power pa transmitter improves ee by only 68 %.
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arxiv:1305.3959
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##sket two 16th - century german grenade muskets working with a wheellock mechanism are on display in the bayerisches nationalmuseum, munich. = = technical drawings of artist - engineers = = the revived scientific spirit of the age can perhaps be best exemplified by the voluminous corpus of technical drawings which the artist - engineers left behind, reflecting the wide variety of interests the renaissance homo universalis pursued. the establishment of the laws of linear perspective by brunelleschi gave his successors, such as taccola, francesco di giorgio martini and leonardo da vinci, a powerful instrument to depict mechanical devices for the first time in a realistic manner. the extant sketch books give modern historians of science invaluable insights into the standards of technology of the time. renaissance engineers showed a strong proclivity to experimental study, drawing a variety of technical devices, many of which appeared for the first time in history on paper. however, these designs were not always intended to be put into practice, and often practical limitations impeded the application of the revolutionary designs. for example, da vinci ' s ideas on the conical parachute or the winged flying machine were only applied much later. while earlier scholars showed a tendency to attribute inventions based on their first pictorial appearance to individual renaissance engineers, modern scholarship is more prone to view the devices as products of a technical evolution which often went back to the middle ages. = = see also = = chariot clock history of science in the renaissance renaissance magic = = notes = = = = footnotes = = = = references = = boruchoff, david a. ( 2012 ), " the three greatest inventions of modern times : an idea and its public. " entangled knowledge : scientific discourses and cultural difference, munster and new york : waxmann, pp. 133 – 136, isbn 978 - 3 - 8309 - 2729 - 7 coulton, j. j. ( 1974 ), " lifting in early greek architecture ", the journal of hellenic studies, 94 : 1 – 19, doi : 10. 2307 / 630416, jstor 630416, s2cid 162973494 eisenstein, elizabeth l. ( 1980 ), the printing press as an agent of change, cambridge university press, isbn 0 - 521 - 29955 - 1 febvre, lucien ; martin, henri - jean ( 1997 ), the coming of the book : the impact of printing 1450 – 1800, london : verso, isbn 1 - 85984 - 108 - 2
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https://en.wikipedia.org/wiki/Renaissance_technology
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we present phase - resolved spectroscopies based on hilbert - huang transform ( hht ) for millihertz quasi - periodic oscillations ( mhz qpos ) in 4u 1636 - 536. this ~ 8 mhz qpo can be detected approximately several thousand seconds before a type - i x - ray burst. it was interpreted as marginally stable burning on the neutron - star surface. in this study, we used hht to analyze the data collected by xmm - newton between 2007 and 2009. hht is a powerful tool that enables us to obtain instantaneous frequency, amplitude and phase of non - stationary periodicity phenomena, such as qpos. with well - defined phases, the oscillation profile of the ~ 8 mhz qpo for 4u 1636 - 53 can be precisely revealed. in addition to the oscillation profile, phase - resolved spectra for the complete cycle are constructed. from the correlation between spectral parameters and fluxes, we find that the oscillation is mainly attributed to the variations of emitting area of blackbody radiation in three out of four observations with mhz qpo detections whereas the other one shows concurrent variation of temperature and flux with a constant emitting area. although the cause of the difference is not clear, it might be related to the spectral state of the source that can be observed from hard color difference in color - color diagram.
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arxiv:2008.09321
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by using klein ' s model for hyperbolic geometry, hyperbolic structures on orbifolds or manifolds provide examples of real projective structures. by andreev ' s theorem, many 3 - dimensional reflection orbifolds admit a finite volume hyperbolic structure, and such a hyperbolic structure is unique. however, the induced real projective structure on some such 3 - orbifolds deforms into a family of real projective structures that are not induced from hyperbolic structures. in this paper, we find new classes of compact and complete hyperbolic reflection 3 - orbifolds with such deformations. we also explain numerical and exact results on projective deformations of some compact hyperbolic cubes and dodecahedra.
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arxiv:1003.4352
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in this work we investigate the inefficiency of the electricity system with strategic agents. specifically, we prove that without a proper control the total demand of an inefficient system is at most twice the total demand of the optimal outcome. we propose an incentives scheme that promotes optimal outcomes in the inefficient electricity market. the economic incentives can be seen as an indirect revelation mechanism that allocates resources using a one - dimensional message space per resource to be allocated. the mechanism does not request private information from users and is valid for any concave customer ' s valuation function. we propose a distributed implementation of the mechanism using population games and evaluate the performance of four popular dynamics methods in terms of the cost to implement the mechanism. we find that the achievement of efficiency in strategic environments might be achieved at a cost, which is dependent on both the users ' preferences and the dynamic evolution of the system. some simulation results illustrate the ideas presented throughout the paper.
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arxiv:1408.5366
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we observe shock - front separation and species - dependent shock widths in multi - ion - species collisional plasma shocks, which are produced by obliquely merging plasma jets of a he / ar mixture ( 97 % he and 3 % ar by initial number density ) on the plasma liner experiment [ s. c. hsu et al., ieee trans. plasma sci. 46, 1951 ( 2018 ) ]. visible plasma emission near the he - i 587. 6 nm and ar - ii 476. 5 - 514. 5 nm lines are simultaneously recorded by splitting a single visible image of the shock into two different fast - framing cameras with different narrow bandpass filters ( 589 + / - 5 nm for observing the he - i line and 500 + / - 25 nm for the ar - ii lines ). for conditions in these experiments ( pre - shock ion and electron densities ~ 5 * 10 ^ 14 cm ^ - 3, ion and electron temperatures of ~ 2. 2 ev, and relative plasma - merging speed of 22 km / s ), the observationally inferred magnitude of he / ar shock - front separation and the shock widths themselves are < 1 cm, which correspond to ~ 50 post - shock thermal ion - ion mean free paths. these experimental lengths scales are in reasonable qualitative and quantitative agreement with results from 1d multi - fluid simulations using the chicago code. however, there are differences between the experimentally - inferred and simulation - predicted ionization states and line emission intensities, particularly in the post - shock region. overall, the experimental and simulation results are consistent with theoretical predictions that the lighter he ions diffuse farther ahead within the overall shock front than the heavier ar ions.
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arxiv:1908.00454
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in - and out - of - plane magnetic penetration depths were measured in three iron - based pnictide superconducting systems. all studied samples of both 122 systems show a robust power - law behavior, $ \ lambda ( t ) t ^ n $, with the sample - dependent exponent n = 2 - 2. 5, which is indicative of unconventional pairing. this scenario could be possible either through scattering in a $ s _ { \ pm } $ state or due to nodes in the superconducting gap. in the nd - 1111 system, the interpretation of data may be obscured by the magnetism of rare - earth ions. the overall anisotropy of the pnictide superconductors is small. the 1111 system is about two times more anisotropic than the 122 system. our data and analysis suggest that the iron - based pnictides are complex superconductors in which a multiband three - dimensional electronic structure and strong magnetic fluctuations play important roles.
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arxiv:0901.3698
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shrinkage priors are a popular bayesian paradigm to handle sparsity in high - dimensional regression. still limited, however, is a flexible class of shrinkage priors to handle grouped sparsity, where covariates exhibit some natural grouping structure. this paper proposes a novel extension of the $ r ^ 2 $ - induced dirichlet decomposition ( r2d2 ) prior to accommodate grouped variable selection in linear regression models. the proposed method, called the group r2d2 prior, employs a dirichlet prior distribution on the coefficient of determination for each group, allowing for a flexible and adaptive shrinkage that operates at both group and individual variable levels. this approach improves the original r2d2 prior to handle grouped predictors, providing a balance between within - group dependence and group - level sparsity. we present several theoretical properties of this proposed prior distribution while also developing a markov chain monte carlo algorithm. through simulation studies and real - data analysis, we demonstrate that our method outperforms traditional shrinkage priors in terms of both estimation accuracy, inference and prediction.
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arxiv:2412.15293
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we introduce fireshape, an open - source and automated shape optimization toolbox for the finite element software firedrake. fireshape is based on the moving mesh method and allows users with minimal shape optimization knowledge to tackle with ease challenging shape optimization problems constrained to partial differential equations ( pdes ).
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arxiv:2005.07264
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we present the results of c18o ( j = 1 - 0 ) mapping observations of a 20 ' x18 ' area in the lynds 1204 molecular cloud associated with the sharpless 2 - 140 ( s140 ) h ii region. the c18o cube ( alpha - delta - vlsr ) data shows that there are three clumps with sizes of \ sim 1 pc in the region. two of them have peculiar red shifted velocity components at their edges, which can be interpreted as the results of the interaction between the cloud and the cepheus bubble. from the c18o cube data, the clumpfind identified 123 c18o cores, which have mean radius, velocity width in fwhm, and lte mass of 0. 36 \ pm0. 07 pc, 0. 37 \ pm0. 09 km s - 1, and 41 \ pm29 msun, respectively. all the cores in s140 are most likely to be gravitationally bound by considering the uncertainty in the c18o abundance. we derived a c18o core mass function ( cmf ), which shows a power - law - like behavior above a turnover at 30 msun. the best - fit power - law index of - 2. 1 \ pm0. 2 is quite consistent with those of the imf and the c18o cmf in the omc - 1 region by ikeda & kitamura ( 2009 ). kramer et al. ( 1998 ) estimated the power - law index of - 1. 65 in s140 from the c18o ( j = 2 - 1 ) data, which is inconsistent with this study. however, the c18o ( j = 2 - 1 ) data are spatially limited to the central part of the cloud and are likely to be biased toward high - mass cores, leading to the flatter cmf. consequently, this study and our previous one strongly support that the power - law form of the imf has been already determined at the density of \ sim 10 ^ { 3 - 4 } cm ^ { - 3 }, traced by the c18o ( j = 1 - 0 ) line.
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arxiv:1103.1712
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while graph neural networks ( gnns ) operating in hyperbolic spaces have shown promise for modeling hierarchical and complex relational data, a critical limitation often overlooked is their potentially limited discriminative power compared to their euclidean counterparts or fundamental graph isomorphism tests like the weisfeiler - lehman ( wl ) hierarchy. existing hyperbolic aggregation schemes, while curvature - aware, may not sufficiently capture the intricate structural differences required to robustly distinguish non - isomorphic graphs owing to non - injective aggregation functions. to address this expressiveness gap in hyperbolic graph learning, we introduce the lorentzian graph isomorphic network ( lgin ), a novel gnn designed to achieve enhanced discriminative capabilities within the lorentzian model of hyperbolic space. lgin proposes a new update rule that effectively combines local neighborhood information with a richer representation of graph structure designed to preserve the lorentzian metric tensor. this represents a significant step towards building more expressive gnns in non - euclidean geometries, overcoming a common bottleneck in current hyperbolic methods. we conduct extensive evaluations across nine diverse benchmark datasets, including molecular and protein structures. lgin consistently outperforms or matches state - of - the - art hyperbolic and euclidean gnns, showcasing its practical efficacy and validating its superior ability to capture complex graph structures and distinguish between different graphs. to the best of our knowledge, lgin is the first work to study the framework behind a powerful gnn on the hyperbolic space. the code for our paper can be found at https : / / github. com / deceptrax123 / lgin
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arxiv:2504.00142
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long - baseline neutrino oscillation experiments, in particular deep underground neutrino experiment ( dune ) and tokai to hyper - kamiokande ( t2hk ), will lead the effort in the precision determination of the as yet unknown parameters of the leptonic mixing matrix. in this article, we revisit the potential of dune, t2hk and their combination in light of the most recent experimental information. as well as addressing more conventional questions, we pay particular attention to the attainable precision on { \ delta }, which is playing an increasingly important role in the physics case of the long - baseline programme. we analyse the complementarity of the two designs, identify the benefit of a programme comprising distinct experiments and consider how best to optimise the global oscillation programme. this latter question is particularly pertinent in light of a number of alternative design options which have recently been mooted : a korean second detector for t2hk and different beams options at dune. we study the impact of these options and quantify the synergies between alternative proposals, identifying the best means of furthering our knowledge of the fundamental physics of neutrino oscillation.
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arxiv:1612.07275
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testing is a crucial control mechanism for an epidemic outbreak because it enables the health authority to detect and isolate the infected cases, thereby limiting the disease transmission to susceptible people, when no effective treatment or vaccine is available. in this paper, an epidemic model that incorporates the testing rate as a control input is presented. the proposed model distinguishes between the undetected infected and the detected infected cases with the latter assumed to be isolated from the disease spreading process in the population. two testing policies, effective during the onset of an epidemic when no treatment or vaccine is available, are devised : ( i ) best - effort strategy for testing ( best ) and ( ii ) constant optimal strategy for testing ( cost ). the best is a suppression policy that provides a lower bound on the testing rate to stop the growth of the epidemic. the cost is a mitigation policy that minimizes the peak of the epidemic by providing a constant, optimal allocation of tests in a certain time interval when the total stockpile of tests is limited. both testing policies are evaluated by their impact on the number of active intensive care unit ( icu ) cases and the cumulative number of deaths due to covid - 19 in france.
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arxiv:2109.12553
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given two subgroups h, k of a finite group g, the probability that a pair of random elements from h and k commutes is denoted by \ pr ( h, k ). we address the following question. let p be a p - subgroup of a finite group g and assume that \ pr ( p, p ^ x ) \ geq \ e > 0 for every x \ in g. is the order of p modulo o _ p ( g ) bounded in terms of e only? with respect to this question, we establish several positive results but show that in general the answer is negative. in particular, we prove that if the composition factors of g which are isomorphic to simple groups of lie type in characteristic p, have lie rank at most n, then the order of p modulo o _ p ( g ) is bounded in terms of n and e only. if p is a sylow p - subgroup of g, then the order of p modulo o _ p ( g ) is bounded in terms e only. some other results of similar flavour are established. we also show that if \ pr ( p _ 1, p _ 2 ) > 0 for every two sylow p - subgroups p _ 1, p _ 2 of a profinite group g, then o _ { p, p ' } ( g ) is open in g.
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arxiv:2505.10521
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surface plasmons or phonons propagating on a two - dimensional ( 2d ) material can exhibit coupling with resonant excitations in its substrate, and the resulting coupled modes were extensively studied. similar coupling of edge modes propagating along a boundary of 2d material with the substrate excitations remains unexplored. this paper aims to bridge this gap by investigating the edge - substrate hybrid modes using the exact wiener - hopf analytical approach. we analyze dispersions, decay rate, and confinement of such hybrid modes both without magnetic field ( plasmon - phonon and phonon - phonon hybrid modes ) and in quantizing magnetic field where edge magnetoplasmons hybridize with substrate phonons. the hybrid modes are predicted to occur in thz and far - ir ranges for several combinations of quasi - 2d materials ( single - and bilayer graphene, quantum wells, thin - film semiconductors ) and substrates with polar - phonon resonances.
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arxiv:2504.08082
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we classify all integrable 3 - dimensional scalar discrete quasilinear equations q = 0 on an elementary cubic cell of the 3 - dimensional lattice. an equation q = 0 is called integrable if it may be consistently imposed on all 3 - dimensional elementary faces of the 4 - dimensional lattice. under the natural requirement of invariance of the equation under the action of the complete group of symmetries of the cube we prove that the only nontrivial ( non - linearizable ) integrable equation from this class is the well - known dbkp - system. ( version 2 : a small correction in table 1 ( p. 7 ) for n = 2 has been made. ) ( version 3 : a few small corrections : one more reference added, the main statement stated more explicitly. )
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arxiv:0706.2464
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through this paper, an attempt has been made to quantify the underlying relationships between the leading macroeconomic indicators. more clearly, an effort has been made in this paper to assess the cointegrating relationships and examine the error correction behavior revealed by macroeconomic variables using econometric techniques that were initially developed by engle and granger ( 1987 ), and further explored by various succeeding papers, with the latest being tu and yi ( 2017 ). gross domestic product, discount rate, consumer price index and population of u. s are representatives of the economy that have been used in this study to analyze the relationships between economic indicators and understand how an adverse change in one of these variables might have ramifications on the others. this is performed to corroborate and guide the belief that a policy maker with specified intentions cannot ignore the spillover effects caused by implementation of a certain policy.
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arxiv:1907.04447
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encouraged by significant advances in algorithms and tools for verification and analysis, high level modeling and programming techniques, natural language programming, etc., we feel it is time for a major change in the way complex software and systems are developed. we present a vision that will shift the power balance between human engineers and the development and runtime environments. the idea is to endow the computer with human - like wisdom - not general wisdom, and not ai in the standard sense of the term - but wisdom geared towards classical system - building, which will be manifested, throughout development, in creativity and proactivity, and deep insights into the system ' s own structure and behavior, its overarching goals and rationale. ideally, the computer will join the development team as an equal partner - knowledgeable, concerned, and responsibly active. we present a running demo of our initial efforts on the topic, illustrating on a small example what we feel is the feasibility of the ideas.
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arxiv:1501.05924
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this paper proposes a deep multi - speaker text - to - speech ( tts ) model for spoofing speaker verification ( sv ) systems. the proposed model employs one network to synthesize time - downsampled mel - spectrograms from text input and another network to convert them to linear - frequency spectrograms, which are further converted to the time domain using the griffin - lim algorithm. both networks are trained separately under the generative adversarial networks ( gan ) framework. spoofing experiments on two state - of - the - art sv systems ( i - vectors and google ' s ge2e ) show that the proposed system can successfully spoof these systems with a high success rate. spoofing experiments on anti - spoofing systems ( i. e., binary classifiers for discriminating real and synthetic speech ) also show a high spoof success rate when such anti - spoofing systems ' structures are exposed to the proposed tts system.
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arxiv:1910.13054
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we report measurements of the superconducting transition temperature, $ t _ c $, in coo / co / cu / co / nb multilayers as a function of the angle $ \ alpha $ between the magnetic moments of the co layers. our measurements reveal that $ t _ c ( \ alpha ) $ is a nonmonotonic function, with a minimum near $ \ alpha = { \ pi } / { 2 } $. numerical self - consistent solutions of the bogoliubov - de gennes equations quantitatively and accurately describe the behavior of $ t _ c $ as a function of $ \ alpha $ and layer thicknesses in these superconductor / spin - valve heterostructures. we show that experimental data and theoretical evidence agree in relating $ t _ c ( \ alpha ) $ to enhanced penetration of the triplet component of the condensate into the co / cu / co spin valve in the maximally noncollinear magnetic configuration.
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arxiv:1404.2304
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we identify a non fermi liquid ( nfl ) class of fixed points describing the infrared behaviour of interacting chiral fermions in one dimension. the thermodynamic properties and asymptotic correlation functions are characterized by universal exponents, which we determine by means of conformal and bethe - ansatz techniques. the mechanism leading to the breakdown of fermi - liquid theory is quite general and can be expected to be realized in systems with broken t - invariance. as an example we study the edge states of interacting qhe systems. we calculate the universal frequency dependence of the spin conductance in these systems as well as the nmr response.
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arxiv:cond-mat/9803134
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herman et al. pointed out that the insertion of run - time checks into a gradually typed program could hamper tail - call optimization and, as a result, worsen the space complexity of the program. to address the problem, they proposed a space - efficient coercion calculus, which was subsequently improved by siek et al. the semantics of these calculi involves eager composition of run - time checks expressed by coercions to prevent the size of a term from growing. however, it relies also on a nonstandard reduction rule, which does not seem easy to implement. in fact, no compiler implementation of gradually typed languages fully supports the space - efficient semantics faithfully. in this paper, we study coercion - passing style, which herman et al. have already mentioned, as a technique for straightforward space - efficient implementation of gradually typed languages. a program in coercion - passing style passes " the rest of the run - time checks " around - - - just like continuation - passing style ( cps ), in which " the rest of the computation " is passed around - - - and ( unlike cps ) composes coercions eagerly. we give a formal coercion - passing translation from $ \ lambda $ s by siek et al. to $ \ lambda $ s $ _ 1 $, which is a new calculus of first - class coercions tailored for coercion - passing style, and prove correctness of the translation. we also implement our coercion - passing style transformation for the grift compiler developed by kuhlenschmidt et al. an experimental result shows stack overflow can be prevented properly at the cost of up to 3 times slower execution for most partially typed practical programs.
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arxiv:1908.02414
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we first investigate the gravitational wave in the flat finsler spacetime. in the finslerian universe, we derive the perturbed gravitational field equation with tensor perturbations. the finslerian background spacetime breaks rotational symmetry and induces parity violation. then we obtain the modified primordial power spectrum of tensor perturbations. the parity violation feature requires that the anisotropic effect contributes to $ tt, te, ee, bb $ angular correlation coefficients with $ l ' = l + 1 $ and $ tb, eb $ with $ l ' = l $. the numerical results show that the anisotropic contributions to angular correlation coefficients depend on $ m $, and $ te $ and $ et $ angular correlation coefficients are different.
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arxiv:1508.04331
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recent renormalization group results predict non self averaging behaviour at criticality for relevant disorder. however, we find strong self averaging ( sa ) behaviour in the critical region of a quenched ising model on an ensemble of small - world networks, despite the relevance of the random bonds at the pure critical point.
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arxiv:cond-mat/0409012
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we give a construction of the monopole bundles over fuzzy complex projective spaces as projective modules. the corresponding chern classes are calculated. they reduce to the monopole charges in the n - > infinity limit, where n labels the representation of the fuzzy algebra.
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arxiv:hep-th/0404130
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let z be an affine algebraic variety and ed ( z ) = max ( 2 dim z + 1, dim tz ). let x be a smooth algebraic variety isomorphic to a semi - simple linear algebraic group whose lie algebra is a sum of special linear lie algebras. we show that if dim x > ed ( z ) - 1, then z admits a closed embedding into x. we also show that for every smooth affine flexible variety y there is a closed embedding of $ z $ into the the product of y and an affine n - space provided that n > dim z - 2 and dim y + n > ed ( z ) - 1.
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arxiv:2104.09550
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we consider the estimation of dynamic discrete choice models in a semiparametric setting, in which the per - period utility functions are known up to a finite number of parameters, but the distribution of utility shocks is left unspecified. this semiparametric setup differs from most of the existing identification and estimation literature for dynamic discrete choice mod - els. to show identification we derive and exploit a new bellman - like recursive representation for the unknown quantile function of the utility shocks. our estimators are straightforward to compute ; some are simple and require no iteration, and resemble classic estimators from the literature on semiparametric regression and average derivative estimation. monte carlo simulations demonstrate that our estimator performs well in small samples. to highlight features of this estimator, we estimate a structural model of dynamic labor supply for new york city taxicab drivers.
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arxiv:1605.08369
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a quinary ( la0. 5ce0. 5 ) 65al10 ( co0. 6cu0. 4 ) 25 alloy with superior glass - forming ability ( gfa ), identified by the formation of fully glassy rod of 32 mm in diameter by tilt - pour casting, was reported. by comparing with the gfa of quarternary ( la0. 5ce0. 5 ) 65al10tm25 and ternary ln65al10tm25 alloys ( ln = la or ce ; tm = co or cu ), we suggest that the strong frustration of crystallization by utilizing the coexistence of la - ce and co - cu to complicate competing crystalline phases is helpful to construct bmg component with superior gfa.
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arxiv:cond-mat/0612184
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although it is generally assumed that there are two dominant classes of gamma - ray bursts ( grb ) with different typical durations, it has been difficult to unambiguously classify grbs as short or long from summary properties such as duration, spectral hardness, and spectral lag. recent work used t - distributed stochastic neighborhood embedding ( t - sne ), a machine learning algorithm for dimensionality reduction, to classify all swift gamma - ray bursts as short or long. here, the method is expanded, using two algorithms, t - sne and umap, to produce embeddings that are used to provide a classification for the 1911 batse bursts, 1321 swift bursts, and 2294 fermi bursts for which both spectra and metadata are available. although the embeddings appear to produce a clear separation of each catalog into short and long bursts, a resampling - based approach is used to show that a small fraction of bursts cannot be robustly classified. further, 3 of the 304 bursts observed by both swift and fermi have robust but conflicting classifications. a likely interpretation is that in addition to the two predominant classes of grbs, there are additional, uncommon types of bursts which may require multi - wavelength observations in order to separate from more typical short and long grbs.
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arxiv:2301.00820
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distributed lag models are useful in environmental epidemiology as they allow the user to investigate critical windows of exposure, defined as the time period during which exposure to a pollutant adversely affects health outcomes. recent studies have focused on estimating the health effects of a large number of environmental exposures, or an environmental mixture, on health outcomes. in such settings, it is important to understand which environmental exposures affect a particular outcome, while acknowledging the possibility that different exposures have different critical windows. further, in the studies of environmental mixtures, it is important to identify interactions among exposures, and to account for the fact that this interaction may occur between two exposures having different critical windows. exposure to one exposure early in time could cause an individual to be more or less susceptible to another exposure later in time. we propose a bayesian model to estimate the temporal effects of a large number of exposures on an outcome. we use spike - and - slab priors and semiparametric distributed lag curves to identify important exposures and exposure interactions, and discuss extensions with improved power to detect harmful exposures. we then apply these methods to estimate the effects of exposure to multiple air pollutants during pregnancy on birthweight from vital records in colorado.
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arxiv:2107.14567
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swimming microorganisms often self propel in fluids with complex rheology. while past theoretical work indicates that fluid viscoelasticity should hinder their locomotion, recent experiments on waving swimmers suggest a possible non - newtonian enhancement of locomotion. we suggest a physical mechanism, based on fluid - structure interaction, leading to swimming in a viscoelastic fluid at a higher speed than in a newtonian one. using taylor ' s two - dimensional swimming sheet model, we solve for the shape of an active swimmer as a balance between the external fluid stresses, the internal driving moments, and the passive elastic resistance. we show that this dynamic balance leads to a generic transition from hindered rigid swimming to enhanced flexible locomotion. the results are physically interpreted as due to a viscoelastic suction increasing the swimming amplitude in a non - newtonian fluid and overcoming viscoelastic damping.
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arxiv:1410.1720
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we present particular and unique solutions of dokshitzer - gribov - lipatov - altarelli - parisi ( dglap ) evolution equations for light sea and valence quark structure functions in leading order ( lo ). we obtain t evolutions of sea and valence quark structure functions and x - evolutions of light sea quark structure functions from dglap evolution equations. the results are compared with a recent global parameterization.
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arxiv:1209.4350
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we investigate the dissipative phase transitions of the anisotropic quantum rabi model with cavity decay and demonstrate that large spin fluctuations persist in the stationary state, having important consequences on the phase diagram and the critical properties. in the second - order phase transition to the superradiant phase, there is a significant suppression of the order parameter and the appearance of non - universal factors, which directly reflect the spin populations. furthermore, upon entering a parameter regime where mean - field theory predicts a tricritical phase, we find a first - order phase transition due to the unexpected collapse of superradiance. an accurate and physically transparent description going beyond mean - field theory is established by combining exact numerical simulations, the cumulant expansion, and analytical approximations based on reduced master equations and an effective equilibrium theory. our findings, compared to the conventional thermodynamic limit of the dicke model, indicate a general tendency of forming extreme non - equilibrium states in the single - spin system, thus have broad implications for dissipative phase transitions of few - body systems.
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arxiv:2312.06376
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in this paper, i attempt a personal account of my understanding of the measurement problem in quantum mechanics, which has been largely in the tradition of the copenhagen interpretation. i assume that ( i ) the quantum state is a representation of knowledge of a ( real or hypothetical ) observer relative to her experimental capabilities ; ( ii ) measurements have definite outcomes in the sense that only one outcome occurs ; ( iii ) quantum theory is universal and the irreversibility of the measurement process is only " for all practical purposes ". these assumptions are analyzed within quantum theory and their consistency is tested in deutsch ' s version of the wigner ' s friend gedanken experiment, where the friend reveals to wigner whether she observes a definite outcome without revealing which outcome she observes. the view that holds the coexistence of the " facts of the world " common both for wigner and his friend runs into the problem of the hidden variable program. the solution lies in understanding that " facts " can only exist relative to the observer.
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arxiv:1507.05255
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recently introduced connections between quantum codes and narain cfts provide a simple ansatz to express a modular - invariant function $ z ( \ tau, \ bar \ tau ) $ in terms of a multivariate polynomial satisfying certain additional properties. these properties include algebraic identities, which ensure modular invariance of $ z ( \ tau, \ bar \ tau ) $, and positivity and integrality of coefficients, which imply positivity and integrality of the $ \ mathfrak { u } ( 1 ) ^ n \ times \ mathfrak { u } ( 1 ) ^ n $ character expansion of $ z ( \ tau, \ bar \ tau ) $. such polynomials come naturally from codes, in the sense that each code of a certain type gives rise to the so - called enumerator polynomial, which automatically satisfies all necessary properties, while the resulting $ z ( \ tau, \ bar \ tau ) $ is the partition function of the code cft - - the narain theory unambiguously constructed from the code. yet there are also ` ` fake ' ' polynomials satisfying all necessary properties, that are not associated with any code. they lead to $ z ( \ tau, \ bar \ tau ) $ satisfying all modular bootstrap constraints ( modular invariance and positivity and integrality of character expansion ), but whether they are partition functions of any actual cft is unclear. we consider the group of the six simplest fake polynomials and denounce the corresponding $ z $ ' s as fake : we show that none of them is the torus partition function of any narain theory. moreover, four of them are not partition functions of any unitary 2d cft ; our analysis for other two is inconclusive. our findings point to an obvious limitation of the modular bootstrap approach : not every solution of the full set of torus modular bootstrap constraints is due to an actual cft. in the paper we consider six simple examples, keeping in mind that thousands more can be constructed.
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arxiv:2211.15699
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many inductive logic programming ( ilp ) methods are incapable of learning programs from probabilistic background knowledge, e. g. coming from sensory data or neural networks with probabilities. we propose propper, which handles flawed and probabilistic background knowledge by extending ilp with a combination of neurosymbolic inference, a continuous criterion for hypothesis selection ( bce ) and a relaxation of the hypothesis constrainer ( noisycombo ). for relational patterns in noisy images, propper can learn programs from as few as 8 examples. it outperforms binary ilp and statistical models such as a graph neural network.
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arxiv:2408.11367
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the esscher transform is a tool of broad utility in various domains of applied probability. it provides the solution to a constrained minimum relative entropy optimization problem. in this work, we study the generalization of the esscher transform to the quantum setting. we examine a relative entropy minimization problem for a quantum density operator, potentially of wide relevance in quantum information theory. the resulting solution form motivates us to define the \ textit { quantum } esscher transform, which subsumes the classical esscher transform as a special case. envisioning potential applications of the quantum esscher transform, we also discuss its implementation on fault - tolerant quantum computers. our algorithm is based on the modern techniques of block - encoding and quantum singular value transformation ( qsvt ). we show that given block - encoded inputs, our algorithm outputs a subnormalized block - encoding of the quantum esscher transform within accuracy $ \ epsilon $ in $ \ tilde o ( \ kappa d \ log ^ 2 1 / \ epsilon ) $ queries to the inputs, where $ \ kappa $ is the condition number of the input density operator and $ d $ is the number of constraints.
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arxiv:2401.07561
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neural networks have led to tremendous performance gains for single - task speech enhancement, such as noise suppression and acoustic echo cancellation ( aec ). in this work, we evaluate whether it is more useful to use a single joint or separate modules to tackle these problems. we describe different possible implementations and give insights into their performance and efficiency. we show that using a separate echo cancellation module and a module for noise and residual echo removal results in less near - end speech distortion and better performance during double - talk at same complexity.
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arxiv:2205.06931
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recent work has advocated for training ai models on ever - larger datasets, arguing that as the size of a dataset increases, the performance of a model trained on that dataset will correspondingly increase ( referred to as " scaling laws " ). in this paper, we draw on literature from the social sciences and machine learning to critically interrogate these claims. we argue that this scaling law relationship depends on metrics used to measure performance that may not correspond with how different groups of people perceive the quality of models ' output. as the size of datasets used to train large ai models grows and ai systems impact ever larger groups of people, the number of distinct communities represented in training or evaluation datasets grows. it is thus even more likely that communities represented in datasets may have values or preferences not reflected in ( or at odds with ) the metrics used to evaluate model performance in scaling laws. different communities may also have values in tension with each other, leading to difficult, potentially irreconcilable choices about metrics used for model evaluations - - threatening the validity of claims that model performance is improving at scale. we end the paper with implications for ai development : that the motivation for scraping ever - larger datasets may be based on fundamentally flawed assumptions about model performance. that is, models may not, in fact, continue to improve as the datasets get larger - - at least not for all people or communities impacted by those models. we suggest opportunities for the field to rethink norms and values in ai development, resisting claims for universality of large models, fostering more local, small - scale designs, and other ways to resist the impetus towards scale in ai.
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arxiv:2307.03201
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we introduce a new technique for proving membership of problems in fixp - the class capturing the complexity of computing a fixed - point of an algebraic circuit. our technique constructs a " pseudogate " which can be used as a black box when building fixp circuits. this pseudogate, which we term the " opt - gate ", can solve most convex optimization problems. using the opt - gate, we prove new fixp - membership results, and we generalize and simplify several known results from the literature on fair division, game theory and competitive markets. in particular, we prove complexity results for two classic problems : computing a market equilibrium in the arrow - debreu model with general concave utilities is in fixp, and computing an envy - free division of a cake with very general valuations is fixp - complete. we further showcase the wide applicability of our technique, by using it to obtain simplified proofs and extensions of known fixp - membership results for equilibrium computation for various types of strategic games, as well as the pseudomarket mechanism of hylland and zeckhauser.
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arxiv:2111.06878
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a theoretical and experimental analysis related to the identification of vertices of unknown shapes is presented. shapes are seen as real functions of their closed boundary. unlike traditional approaches, which see curvature as the rate of change of the tangent to the curve, an alternative global perspective of curvature is examined providing insight into the process of noise - enabled vertex localization. the analysis leads to a paradox, that certain vertices can be localized better in the presence of noise. the concept of noising is thus considered and a relevant global method for localizing " global vertices " is investigated. theoretical analysis reveals that induced noise can help localizing certain vertices if combined with global descriptors. experiments with noise and a comparison to localized methods validate the theoretical results.
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arxiv:1608.00668
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tracer tests in natural porous media sometimes show abnormalities that suggest considering a fractional variant of the advection diffusion equation supplemented by a time derivative of non - integer order. we are describing an inverse method for this equation : it finds the order of the fractional derivative and the coefficients that achieve minimum discrepancy between solution and tracer data. using an adjoint equation divides the computational effort by an amount proportional to the number of freedom degrees, which becomes large when some coefficients depend on space. method accuracy is checked on synthetical data, and applicability to actual tracer test is demonstrated.
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arxiv:1608.08363
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the totem experiment has been designed to measure the total proton - proton cross section and to study the elastic and diffractive scattering at the lhc energy. the measurement requires detecting protons at distances as small as 1 mm from the beam center : totem uses roman pots, movable beam pipe insertions, hosting silicon detectors. in the first period of lhc operation no relevant problems were detected with roman pots retracted or inserted during special runs. however, when operating the lhc with high intensity beams, impedance induced heating has been observed during the roman pots insertion. in order to be compatible with the higher lhc beam current foreseen after the ls1, a new version of the roman pot has been proposed and optimized with respect to the beam coupling impedance. in this work we present the bench impedance measurements carried out on the new roman pot prototype. single and double wire measurements, as well as probe measurements, were performed in order to detect possible harmful resonant modes. the laboratory setup has been as well simulated with the help of cst particle studio in order to benchmark the measurement results. measurements and simulations are in close agreement confirming the equipment compatibility with the lhc requirements for safe operation.
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arxiv:1612.02200
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a new method to investigate anomalous diffusion in human brain is proposed. the method has been inspired by both the stretched - exponential model proposed by hall and barrick ( hb ) and dti. quantities extracted using hb method were able to discriminate different cerebral tissues on the basis of their complexity, expressed by the stretching exponent gamma and of the anisotropy of gamma across different directions. nevertheless, these quantities were not defined as scalar invariants like mean diffusivity and fractional anisotropy, which are eigenvalues of the diffusion tensor. we hypotesize instead that the signal may be espressed as a simple stretched - exponential only along the principal axes of diffusion, while in a generic direction the signal is modeled as a combination of three different stretched - exponentials. in this way, we derived indices to quantify both the tissue anomalous diffusion and its anisotropy, independently of the reference frame of the experiment. we tested and compare our new method with dti and hb approaches applying them to 10 healty subjects brain at 3t. our experimental results show that our parameters are highly correlated to intrinsic local geometry when compared to hb indices. moreover, they offer a different kind of contrast when compared to dti outputs. specifically, our indices show a higher capability to discriminate among different areas of the corpus callosum, which are known to be associated to different axonal densities.
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arxiv:1004.2001
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using renormalization group methods we study multifractality in directed percolation. our approach is based on random lattice networks consisting of resistor like and diode like bonds with microscopic noise. these random resistor diode networks capture the features of isotropic as well as directed percolation. in this note we introduce a field theoretic hamiltonian for the multifractal properties at the transition from the non - percolating to the directed percolating phase. we investigate the multifractal moments of the current distribution and determine a family of critical exponents for these moments to two - loop order.
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arxiv:cond-mat/0106252
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large vision - language models ( vlms ) such as gpt - 4 have achieved unprecedented performance in response generation, especially with visual inputs, enabling more creative and adaptable interaction than large language models such as chatgpt. nonetheless, multimodal generation exacerbates safety concerns, since adversaries may successfully evade the entire system by subtly manipulating the most vulnerable modality ( e. g., vision ). to this end, we propose evaluating the robustness of open - source large vlms in the most realistic and high - risk setting, where adversaries have only black - box system access and seek to deceive the model into returning the targeted responses. in particular, we first craft targeted adversarial examples against pretrained models such as clip and blip, and then transfer these adversarial examples to other vlms such as minigpt - 4, llava, unidiffuser, blip - 2, and img2prompt. in addition, we observe that black - box queries on these vlms can further improve the effectiveness of targeted evasion, resulting in a surprisingly high success rate for generating targeted responses. our findings provide a quantitative understanding regarding the adversarial vulnerability of large vlms and call for a more thorough examination of their potential security flaws before deployment in practice. code is at https : / / github. com / yunqing - me / attackvlm.
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arxiv:2305.16934
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a model is proposed to study the possible pairing structures of n - boson systems with nonzero spin. analytical solutions have been obtained. the emphasis is placed on the spin - structures of ground states with attractive or repulsive pairing force, and with or without the action of a magnetic field. a quantity ( an analogue of the two - body density function ) is defined to study the spin - correlation between two bosons in n - body systems. the excitation of the system has also been studied.
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arxiv:0903.1902
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explicit theory axioms are added by a saturation - based theorem prover as one of the techniques for supporting theory reasoning. while simple and effective, adding theory axioms can also pollute the search space with many irrelevant consequences. as a result, the prover often gets lost in parts of the search space where the chance to find a proof is low. in this paper we describe a new strategy for controlling the amount of reasoning with explicit theory axioms. the strategy refines a recently proposed two - layer - queue clause selection and combines it with a heuristical measure of the amount of theory reasoning in the derivation of a clause. we implemented the new strategy in the automatic theorem prover vampire and present an evaluation showing that our work dramatically improves the state - of - the - art clause - selection strategy in the presence of theory axioms.
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arxiv:2001.09705
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}. } ( here, μ × cld ν { \ displaystyle \ mu \ times _ { \ text { cld } } \ nu } is the measure defined in theorem 39. 1 in berberian ' 65. ) = = = localizable measures = = = localizable measures are a special case of semifinite measures and a generalization of sigma - finite measures. let x { \ displaystyle x } be a set, let a { \ displaystyle { \ cal { a } } } be a sigma - algebra on x, { \ displaystyle x, } and let μ { \ displaystyle \ mu } be a measure on a. { \ displaystyle { \ cal { a } }. } let f { \ displaystyle \ mathbb { f } } be r { \ displaystyle \ mathbb { r } } or c, { \ displaystyle \ mathbb { c }, } and let t : l f ∞ ( μ ) → ( l f 1 ( μ ) ) ∗ : g ↦ t g = ( f g d μ ) f ∈ l f 1 ( μ ). { \ displaystyle t : l _ { \ mathbb { f } } ^ { \ infty } ( \ mu ) \ to \ left ( l _ { \ mathbb { f } } ^ { 1 } ( \ mu ) \ right ) ^ { * } : g \ mapsto t _ { g } = \ left ( \ int fgd \ mu \ right ) _ { f \ in l _ { \ mathbb { f } } ^ { 1 } ( \ mu ) }. } then μ { \ displaystyle \ mu } is localizable if and only if t { \ displaystyle t } is bijective ( if and only if l f ∞ ( μ ) { \ displaystyle l _ { \ mathbb { f } } ^ { \ infty } ( \ mu ) } " is " l f 1 ( μ ) ∗ { \ displaystyle l _ { \ mathbb { f } } ^ { 1 } ( \ mu ) ^ { * } } ). = = = s - finite measures = = = a measure is said to be s - finite if it is a countable sum of finite measures. s - finite measures are more general than sigma - finite ones and have applications in the theory of stochastic processes. = = non - measurable sets = = if the axiom of
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https://en.wikipedia.org/wiki/Measure_(mathematics)
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robust and accurate localization for unmanned aerial vehicles ( uavs ) is an essential capability to achieve autonomous, long - range flights. current methods either rely heavily on gnss, face limitations in visual - based localization due to appearance variances and stylistic dissimilarities between camera and reference imagery, or operate under the assumption of a known initial pose. in this paper, we developed a gnss - denied localization approach for uavs that harnesses both visual - inertial odometry ( vio ) and visual place recognition ( vpr ) using a foundation model. this paper presents a novel vision - based pipeline that works exclusively with a nadir - facing camera, an inertial measurement unit ( imu ), and pre - existing satellite imagery for robust, accurate localization in varied environments and conditions. our system demonstrated average localization accuracy within a $ 20 $ - meter range, with a minimum error below $ 1 $ meter, under real - world conditions marked by drastic changes in environmental appearance and with no assumption of the vehicle ' s initial pose. the method is proven to be effective and robust, addressing the crucial need for reliable uav localization in gnss - denied environments, while also being computationally efficient enough to be deployed on resource - constrained platforms.
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arxiv:2310.16299
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we construct an infinite finitely generated recursively presented residually finite algorithmically finite group $ g $ answering thereby a question of myasnikov and osin. moreover, $ g $ is " very infinite " and " very algorithmically finite " in the sense that $ g $ contains an infinite abelian normal subgroup while all finite cartesian powers of $ g $ are algorithmically finite ( i. e., for any positive integer $ n $, there is no algorithm which writes out an infinite sequence of pairwise different elements of $ g ^ n $ ). we also state several related problems.
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arxiv:1402.0887
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properly understanding the performances of classifiers is essential in various scenarios. however, the literature often relies only on one or two standard scores to compare classifiers, which fails to capture the nuances of application - specific requirements. the tile is a recently introduced visualization tool organizing an infinity of ranking scores into a 2d map. thanks to the tile, it is now possible to compare classifiers efficiently, displaying all possible application - specific preferences instead of having to rely on a pair of scores. this hitchhiker ' s guide to understanding the performances of two - class classifiers presents four scenarios showcasing different user profiles : a theoretical analyst, a method designer, a benchmarker, and an application developer. we introduce several interpretative flavors adapted to the user ' s needs by mapping different values on the tile. we illustrate this guide by ranking and analyzing the performances of 74 state - of - the - art semantic segmentation models through the perspective of the four scenarios. through these user profiles, we demonstrate that the tile effectively captures the behavior of classifiers in a single visualization, while accommodating an infinite number of ranking scores. code for mapping the different tile flavors is available in supplementary material.
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arxiv:2412.04377
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we determine explicitly the modular flow and the modular hamiltonian for massless free fermions in diamonds on a cylinder in 1 + 1 dimensions. we consider both periodic and antiperiodic boundary conditions, the ground state in the antiperiodic case and the most general family of quasi - free zero - energy ground states in the periodic case, which depend on four parameters and are generally mixed. while for the antiperiodic ground state and one periodic ground state ( the maximally mixed zero - temperature state ) the modular data is known, our results for the generic ground state in the periodic case are completely new. we find that generically both the modular flow and the modular hamiltonian are non - local, and we show that in the parametric limit where the state becomes pure the modular data becomes local. moreover, even in the local case the modular flow generically mixes the two chiralities. this kind of behavior has not been observed previously.
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arxiv:2406.19360
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we show that the characteristic cycle of the exterior product of constructible complexes is the exterior product of the characteristic cycles of factors. this implies the compatibility of characteristic cycles with smooth pull - back which is a first step in the proof of the index formula.
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arxiv:1607.03157
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in this paper, a link diagram is said to be minimal if no reidemeister move i or ii can be applied to it to reduce the number of crossings. we show that for an arbitrary diagram d of a link without a trivial split component, a minimal diagram obtained by applying reidemeister moves i and ii to d is unique. the proof also shows that the number of crossings of such a minimal diagram is unique for any diagram of any link. as the unknot admits infinitely many non - trivial minimal diagrams, we see that every link has infinitely many minimal diagrams, by considering the connected sums with such diagrams. we show that for a link without a trivial split component, an arbitrary reidemeister move iii either does not change the associated minimal diagram or can be reduced to a special type of a move up to reidemeister moves i and ii.
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arxiv:1612.00764
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we study the properties of gluons in qcd in the maximally abelian ( ma ) gauge. in the ma gauge, the off - diagonal gluon behaves as the massive vector boson with the mass $ \ meff \ simeq 1. 2 { \ rm gev } $, and therefore the off - diagonal gluon cannot carry the long - range interaction for $ r \ gg \ meff ^ { - 1 } \ simeq 0. 2 $ fm. the essence of the infrared abelian dominance in the ma gauge is physically explained with the generation of the off - diagonal gluon mass $ \ meff \ simeq 1. 2 { \ rm gev } $ induced by the ma gauge fixing, and the off - diagonal gluon mass generation would predict general infrared abelian dominance in qcd in the ma gauge. we report also the off - diagonal gluon propagator at finite temperature.
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arxiv:hep-lat/9909096
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the late - time equilibrium behavior of generic interacting models is determined by the coupled hydrodynamic equations associated with the globally conserved quantities. in the presence of an external time - dependent drive, non - integrable systems typically thermalize to an effectively infinite - temperature state, losing all memory of their initial states. however, in the presence of a large time - periodic floquet drive, there exist special points in phase - space where the strongly interacting system develops approximate { \ it emergent } conservation laws. here we present results for an exactly solvable model of two coupled chaotic quantum dots with multiple orbitals interacting via random two and four - fermion interactions in the presence of a floquet drive. we analyze the phenomenology of dynamically generated freezing using a combination of exact diagonalization, and field - theoretic analysis in the limit of a large number of electronic orbitals. the model displays universal freezing behavior irrespective of whether the theory is averaged over the disorder configurations or not. we present explicit computations for the growth of many - body chaos and entanglement entropy, which demonstrates the long - lived coherence associated with the interacting degrees of freedom even at late - times at the dynamically frozen points. we also compute the slow timescale that controls relaxation away from exact freezing in a high - frequency expansion.
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arxiv:2405.01627
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rydberg atomic quantum receivers exhibit great potential in assisting classical wireless communications due to their outstanding advantages in detecting radio frequency signals. to realize this potential, we integrate a rydberg atomic quantum receiver into a classical multi - user multiple - input multiple - output ( mimo ) scheme to form a multi - user rydberg atomic quantum mimo ( raq - mimo ) system for the uplink. to study this system, we first construct an equivalent baseband signal model, which facilitates convenient system design, signal processing and optimizations. we then study the ergodic achievable rates under both the maximum ratio combining ( mrc ) and zero - forcing ( zf ) schemes by deriving their tight lower bounds. we next compare the ergodic achievable rates of the raq - mimo and the conventional massive mimo schemes by offering a closed - form expression for the difference of their ergodic achievable rates, which allows us to directly compare the two systems. our results show that raq - mimo allows the average transmit power of users to be $ > 25 $ dbm lower than that of the conventional massive mimo. viewed from a different perspective, an extra $ \ sim 8. 8 $ bits / s / hz / user rate becomes achievable by zf raq - mimo.
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arxiv:2501.18382
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we present new evolution sequences for very low mass stars, brown dwarfs and giant planets and use them to explore a variety of influences on the evolution of these objects. we compare our results with previous work and discuss the causes of the differences and argue for the importance of the surface boundary condition provided by atmosphere models including clouds. the l - to t - type ultracool dwarf transition can be accommodated within the ackerman & marley ( 2001 ) cloud model by varying the cloud sedimentation parameter. we develop a simple model for the evolution across the l / t transition. by combining the evolution calculation and our atmosphere models, we generate colors and magnitudes of synthetic populations of ultracool dwarfs in the field and in galactic clusters. we focus on near infrared color - magnitude diagrams ( cmds ) and on the nature of the ` ` second parameter ' ' that is responsible for the scatter of colors along the teff sequence. variations in metallicity and cloud parameters, unresolved binaries and possibly a relatively young population all play a role in defining the spread of brown dwarfs along the cooling sequence. we find that the transition from cloudy l dwarfs to cloudless t dwarfs slows down the evolution and causes a pile up of substellar objects in the transition region, in contradiction with previous studies. we apply the same model to the pleiades brown dwarf sequence. taken at face value, the pleiades data suggest that the l / t transition occurs at lower teff for lower gravity objects. the simulated populations of brown dwarfs also reveal that the phase of deuterium burning produces a distinctive feature in cmds that should be detectable in ~ 50 - 100 myr old clusters.
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arxiv:0808.2611
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power system communication networks enable operators to remotely monitor and control field equipment. the sophistication of these networks is also increasing as operators continue the trend towards digitization, which is beneficial in integrating distributed energy resources. however, as the attack surface increases in size so too does the risk of cyberattacks. the topology, configuration and composition of communication networks is therefore confidential since this can provide information to attackers. as a result, the number of benchmarks available for research purposes is limited. a tool for procedurally generating communication network topologies is therefore proposed. while primarily intended as an enabler for public research into communication networks, this tool also allows general insights to be gained into the effect of communication network design on the vulnerability of networks to cyberattacks. the tool includes the ability to encapsulate network characteristics in json specification files, which is demonstrated with example advanced metering infrastructure ( ami ), supervisory control and data acquisition ( scada ) and wide area monitoring ( wam ) specification files. the scada network generation is then compared to a real - world case. finally, the effect of network redundancy on the networks cyber resilience is investigated.
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arxiv:2410.09405
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we obtain a characterization of all wavelets leading to analytic wavelet transforms ( wt ). the characterization is obtained as a by - product of the theoretical foundations of a new method for wavelet phase reconstruction from magnitude - only coefficients. the cornerstone of our analysis is an expression of the partial derivatives of the continuous wt, which results in phase - magnitude relationships similar to the short - time fourier transform ( stft ) setting and valid for the generalized family of cauchy wavelets. we show that the existence of such relations is equivalent to analyticity of the wt up to a multiplicative weight and a scaling of the mother wavelet. the implementation of the new phaseless reconstruction method is considered in detail and compared to previous methods. it is shown that the proposed method provides significant performance gains and a great flexibility regarding accuracy versus complexity. additionally, we discuss the relation between scalogram reassignment operators and the wavelet transform phase gradient and present an observation on the phase around zeros of the wt.
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arxiv:1906.00738
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swift j1858. 6 - 0814 is a transient neutron star x - ray binary discovered in october 2018. multi - wavelength follow - up observations across the electromagnetic spectrum revealed many interesting properties, such as erratic flaring on minute timescales and evidence for wind outflows at both x - ray and optical wavelengths, strong and variable local absorption, and an anomalously hard x - ray spectrum. here, we report on a detailed radio observing campaign consisting of one observation at 5. 5 / 9 ghz with the australia telescope compact array, and nine observations at 4. 5 / 7. 5 ghz with the karl g. jansky very large array. a radio counterpart with a flat to inverted radio spectrum is detected in all observations, consistent with a compact jet being launched from the system. swift j1858. 6 - 0814 is highly variable at radio wavelengths in most observations, showing significant variability when imaged on 3 - to - 5 - minute timescales and changing up to factors of 8 within 20 minutes. the periods of brightest radio emission are not associated with steep radio spectra, implying they do not originate from the launching of discrete ejecta. we find that the radio variability is similarly unlikely to have a geometric origin, be due to scintillation, or be causally related to the observed x - ray flaring. instead, we find that it is consistent with being driven by variations in the accretion flow propagating down the compact jet. we compare the radio properties of swift j1858. 6 - 0814 with those of eddington - limited x - ray binaries with similar x - ray and optical characteristics, but fail to find a match in radio variability, spectrum, and luminosity.
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arxiv:2006.06425
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we investigate the low - luminosity supernova sn 2016bkv and its peculiar early - time interaction. for that, we compute radiative transfer models using the cmfgen code. because sn 2016bkv shows signs of interaction with material expelled by its progenitor, it offers a great opportunity to constrain the uncertain evolutionary channels leading to low - luminosity supernovae. our models indicate that the progenitor had a mass - loss rate of ( 6. 0 + - 2. 0 ) x 1e - 4 msun / yr ( assuming a velocity of 150 km / s ). the surface abundances of the progenitor are consistent with solar contents of he and cno. if sn 2016bkv ' s progenitor evolved as a single star, it was an odd red supergiant that did not undergo the expected dredge up for some reason. we propose that the progenitor more likely evolved through binary interaction. one possibility is that the primary star accreted unprocessed material from a companion and avoided further rotational and convective mixing until the sn explosion. another possibility is a merger with a lower mass star, with the primary remaining with low n abundance until core collapse. given the available merger models, we can only put a loose constraint on the pre - explosion mass around 10 - 20 msun, with lower values being favored based on previous observational constraints from the nebular phase.
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arxiv:2108.09037
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we prove a result on lower bounds in large dimensions.
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arxiv:1212.5329
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vertical federated learning has garnered significant attention as it allows clients to train machine learning models collaboratively without sharing local data, which protects the client ' s local private data. however, existing vfl methods face challenges when dealing with heterogeneous local models among participants, which affects optimization convergence and generalization. to address this challenge, this paper proposes a novel approach called vertical federated learning for training multiple heterogeneous models ( vfedmh ). vfedmh focuses on aggregating the local embeddings of each participant ' s knowledge during forward propagation. to protect the participants ' local embedding values, we propose an embedding protection method based on lightweight blinding factors. in particular, participants obtain local embedding using local heterogeneous models. then the passive party, who owns only features of the sample, injects the blinding factor into the local embedding and sends it to the active party. the active party aggregates local embeddings to obtain global knowledge embeddings and sends them to passive parties. the passive parties then utilize the global embeddings to propagate forward on their local heterogeneous networks. however, the passive party does not own the sample labels, so the local model gradient cannot be calculated locally. to overcome this limitation, the active party assists the passive party in computing its local heterogeneous model gradients. then, each participant trains their local model using the heterogeneous model gradients. the objective is to minimize the loss value of their respective local heterogeneous models. extensive experiments are conducted to demonstrate that vfedmh can simultaneously train multiple heterogeneous models with heterogeneous optimization and outperform some recent methods in model performance.
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arxiv:2310.13367
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cone - beam breast computed tomography ( ct ) provides true 3d breast images with isotropic resolution and high - contrast information, detecting calcifications as small as a few hundred microns and revealing subtle tissue differences. however, breast is highly sensitive to x - ray radiation. it is critically important for healthcare to reduce radiation dose. few - view cone - beam ct only uses a fraction of x - ray projection data acquired by standard cone - beam breast ct, enabling significant reduction of the radiation dose. however, insufficient sampling data would cause severe streak artifacts in ct images reconstructed using conventional methods. in this study, we propose a deep - learning - based method to establish a residual neural network model for the image reconstruction, which is applied for few - view breast ct to produce high quality breast ct images. we respectively evaluate the deep - learning - based image reconstruction using one third and one quarter of x - ray projection views of the standard cone - beam breast ct. based on clinical breast imaging dataset, we perform a supervised learning to train the neural network from few - view ct images to corresponding full - view ct images. experimental results show that the deep learning - based image reconstruction method allows few - view breast ct to achieve a radiation dose < 6 mgy per cone - beam ct scan, which is a threshold set by fda for mammographic screening.
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arxiv:1909.11721
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in light filamentation induced by axicon - generated, powerful bessel beams, the spatial propagation dynamics in the nonlinear medium determines the geometry of the filament channel and hence its potential applications. we show that the observed steady and unsteady bessel beam propagation regimes can be understood in a unified way from the existence of an attractor and its stability properties. the attractor is identified as the nonlinear unbalanced bessel beam ( nl - ubb ) whose inward h \ " ankel beam amplitude equals the amplitude of the linear bessel beam that the axicon would generate in linear propagation. a simple analytical formula that determines de nl - ubb attractor is given. steady or unsteady propagation depends on whether the attracting nl - ubb has a small, exponentially growing, unstable mode. in case of unsteady propagation, periodic, quasi - periodic or chaotic dynamics after the axicon reproduces similar dynamics after the development of the small unstable mode into the large perturbation regime.
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arxiv:1508.05877
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we report the observation of a two - dimensional dam break flow of a photon fluid in a nonlinear optical crystal. by precisely shaping the amplitude and phase of the input wave, we investigate the transition from one - dimensional ( 1d ) to two - dimensional ( 2d ) nonlinear dynamics. we observe wave breaking in both transverse spatial dimensions with characteristic timescales determined by the aspect ratio of the input box - shaped field. the interaction of dispersive shock waves propagating in orthogonal directions gives rise to a 2d ensemble of solitons. depending on the box size, we report the evidence of a dynamic phase characterized by a constant number of solitons, resembling a 1d solitons gas in integrable systems. we measure the statistical features of this gaseous - like phase. our findings pave the way to the investigation of collective solitonic phenomena in two dimensions, demonstrating that the loss of integrability does not disrupt the dominant phenomenology.
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arxiv:2409.18738
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calibration of individual based models ( ibms ), successful in modeling complex ecological dynamical systems, is often performed only ad - hoc. bayesian inference can be used for both parameter estimation and uncertainty quantification, but its successful application to realistic scenarios has been hindered by the complex stochastic nature of ibms. computationally expensive techniques such as particle filter ( pf ) provide marginal likelihood estimates, where multiple model simulations ( particles ) are required to get a sample from the state distribution conditional on the observed data. particle ensembles are re - sampled at each data observation time, requiring particle destruction and replication, which lead to an increase in algorithmic complexity. we present spux, a python implementation of parallel particle markov chain monte carlo ( pmcmc ) algorithm, which mitigates high computational costs by distributing particles over multiple computational units. adaptive load re - balancing techniques are used to mitigate computational work imbalances introduced by re - sampling. framework performance is investigated and significant speed - ups are observed for a simple predator - prey ibm model.
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arxiv:1711.01410
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we study an asymptotical behavior of the maximal degree in the degree distribution in an evolving tree model combining the local choice and the mori ' s preferential attachment. in the considered model, the random graph is constructed in the following way. at each step, a new vertex is introduced. then, we connect it with one ( the vertex with the largest degree is chosen ) of $ d $ ( for random $ d $ ) possible neighbors, which are sampled from the set of the existing vertices with the probability proportional to their degrees plus some parameter $ \ beta > - 1 $. it is known that the maximum of the degree distribution for non - random $ d > 2 $ has linear behaviour and, for $ d = 2 $, asymptoticaly equals to $ n / \ ln n $ up to a constant factor. we prove that if $ \ mathbb { e } d < 2 + \ beta $, the maximal degree has sublinear behavior with the power $ \ mathbb { e } d / ( 2 + \ beta ) $ ( as in the preferential attachment without choice ), if $ \ mathbb { e } d > 2 + \ beta $, it has linear behavior and if $ \ mathbb { e } d = 2 + \ beta $ the maximal degree is of order $ n / \ ln n $. the proof combines standard preferential attachment approaches with martingales and stochastic approximation techniques. we also use stochastic approximation results to get a multidimentional central limit theorem for the numbers of vertices with fixed degrees.
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arxiv:1612.02229
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many partial differential equations ( pdes ) do not have analytical solution, and can only be solved by numerical methods. in this context, physics - informed neural networks ( pinn ) have become important in the last decades, since it uses a neural network and physical conditions to approximate any functions. this paper focuses on hypertuning of a pinn, used to solve a pde. the behavior of the approximated solution when we change the learning rate or the activation function ( sigmoid, hyperbolic tangent, gelu, relu and elu ) is here analyzed. a comparative study is done to determine the best characteristics in the problem, as well as to find a learning rate that allows fast and satisfactory learning. gelu and hyperbolic tangent activation functions exhibit better performance than other activation functions. a suitable choice of the learning rate results in higher accuracy and faster convergence.
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arxiv:2211.09380
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the asymptotic mean number of distinct sites visited by a subdiffusive continuous time random walker in two dimensions seems not to have been explicitly calculated anywhere in the literature. this number has been calculated for other dimensions for only one specific asymptotic behavior of the waiting time distribution between steps. we present an explicit derivation for two cases in all integer dimensions so as to formally complete a tableaux of results. in this tableaux we include the dominant as well as subdominant contributions in all integer dimensions. other quantities that can be calculated from the mean number of distinct sites visited are also discussed.
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arxiv:0711.1422
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we give a global, intrinsic, and co - ordinate - free quantization formalism for gromov - witten invariants and their b - model counterparts, which simultaneously generalizes the quantization formalisms described by witten, givental, and aganagic - bouchard - klemm. descendant potentials live in a fock sheaf, consisting of local functions on givental ' s lagrangian cone that satisfy the ( 3g - 2 ) - jet condition of eguchi - xiong ; they also satisfy a certain anomaly equation, which generalizes the holomorphic anomaly equation of bershadsky - cecotti - ooguri - vafa. we interpret givental ' s formula for the higher - genus potentials associated to a semisimple frobenius manifold in this setting, showing that, in the semisimple case, there is a canonical global section of the fock sheaf. this canonical section automatically has certain modularity properties. when x is a variety with semisimple quantum cohomology, a theorem of teleman implies that the canonical section coincides with the geometric descendant potential defined by gromov - witten invariants of x. we use our formalism to prove a higher - genus version of ruan ' s crepant transformation conjecture for compact toric orbifolds. when combined with our earlier joint work with jiang, this shows that the total descendant potential for compact toric orbifold x is a modular function for a certain group of autoequivalences of the derived category of x.
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arxiv:1411.7039
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strong - to - weak spontaneous symmetry breaking ( swssb ) has recently emerged as a universal feature of quantum mixed - state phases of matter. while various information - theoretic diagnostics have been proposed to define and characterize swssb phases, relating these diagnostics to observables which can be efficiently and scalably probed on modern quantum devices remains challenging. here we propose a new observable for swssb in mixed states, called the r \ ' enyi - 1 correlator, which naturally suggests a route toward scalably detecting certain swssb phases in experiment. specifically, if the canonical purification ( cp ) of a given mixed state can be reliably prepared, then swssb in the mixed state can be detected via ordinary two - point correlation functions in the cp state. we discuss several simple examples of cp states which can be efficiently prepared on quantum devices, and whose reduced density matrices exhibit swssb. the r \ ' enyi - 1 correlator also satisfies several useful theoretical properties : it naturally inherits a stability theorem recently proven for the closely related fidelity correlator, and it directly defines swssb as a particular pattern of ordinary spontaneous symmetry breaking in the cp state.
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arxiv:2410.23512
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it is well - known that special 2 - groups can be described in terms of quadratic maps over fields of characteristic 2. in this article we develop methods to compute conjugacy classes, complex representations and characters of a real special $ 2 $ - group using quadratic maps alone.
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arxiv:1510.06583
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supermassive black holes require a reservoir of cold gas at the centre of their host galaxy in order to accrete and shine as active galactic nuclei ( agn ). major mergers have the ability to drive gas rapidly inwards, but observations trying to link mergers with agn have found mixed results due to the difficulty of consistently identifying galaxy mergers in surveys. this study applies deep learning to this problem, using convolutional neural networks trained to identify simulated post - merger galaxies from survey - realistic imaging. this provides a fast and repeatable alternative to human visual inspection. using this tool, we examine a sample of ~ 8500 seyfert 2 galaxies ( l [ oiii ] ~ $ 10 ^ { 38. 5 - 42 } $ erg / s ) at z < 0. 3 in the sloan digital sky survey and find a merger fraction of $ 2. 19 _ { - 0. 17 } ^ { + 0. 21 } $ % compared with inactive control galaxies, in which we find a merger fraction of $ 2. 96 _ { - 0. 20 } ^ { + 0. 26 } $ %, indicating an overall lack of mergers among agn hosts compared with controls. however, matching the controls to the agn hosts in stellar mass and star formation rate reveals that agn hosts in the star - forming blue cloud exhibit a ~ $ 2 \ times $ merger enhancement over controls, while those in the quiescent red sequence have significantly lower relative merger fractions, leading to the observed overall deficit due to the differing $ m _ { \ ast } - $ sfr distributions. we conclude that while mergers are not the dominant trigger of all low - luminosity, obscured agn activity in the nearby universe, they are more important to agn fuelling in galaxies with higher cold gas mass fractions as traced through star formation.
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arxiv:2401.09632
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