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philosophers silvio funtowicz and jerome r. ravetz " pseudo - science may be defined as one where the uncertainty of its inputs must be suppressed, lest they render its outputs totally indeterminate ". the definition, in the book uncertainty and quality in science for policy, alludes to the loss of craft skills in handling quantitative information, and to the bad practice of achieving precision in prediction ( inference ) only at the expenses of ignoring uncertainty in the input which was used to formulate the prediction. this use of the term is common among practitioners of post - normal science. understood in this way, pseudoscience can be fought using good practices to assess uncertainty in quantitative information, such as nusap and β in the case of mathematical modelling β sensitivity auditing. = = history = = the history of pseudoscience is the study of pseudoscientific theories over time. a pseudoscience is a set of ideas that presents itself as science, while it does not meet the criteria to be properly called such. distinguishing between proper science and pseudoscience is sometimes difficult. one proposal for demarcation between the two is the falsification criterion, attributed most notably to the philosopher karl popper. in the history of science and the history of pseudoscience it can be especially difficult to separate the two, because some sciences developed from pseudosciences. an example of this transformation is the science of chemistry, which traces its origins to the pseudoscientific or pre - scientific study of alchemy. the vast diversity in pseudosciences further complicates the history of science. some modern pseudosciences, such as astrology and acupuncture, originated before the scientific era. others developed as part of an ideology, such as lysenkoism, or as a response to perceived threats to an ideology. examples of this ideological process are creation science and intelligent design, which were developed in response to the scientific theory of evolution. = = indicators of possible pseudoscience = = a topic, practice, or body of knowledge might reasonably be termed pseudoscientific when it is presented as consistent with the norms of scientific research, but it demonstrably fails to meet these norms. = = = use of vague, exaggerated or untestable claims = = = assertion of scientific claims that are vague rather than precise, and that lack specific measurements. assertion of a claim with little or no explanatory power. failure to make use of operational definitions ( i. e., publicly accessible definitions of
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https://en.wikipedia.org/wiki/Pseudoscience
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the wfpc2 camera aboard the hst was used to obtain images of the planetary nebula bd + 30 3639 at two epochs separated by 5. 663 years. the expansion of the nebula in the h - alpha and [ n ii ] bands has been measured using several methods. detailed expansion maps for both emission lines were constructed from nearly 200 almost independent features. there is good agreement between the ( independent ) h - alpha and [ n ii ] proper motions. the central velocity split is measured from the stis echelle spectra of the c ii ] 2326a multiplet to be + / - 36. 3 km / s at a position angle of 99 degrees. the angular displacement along this slit position was measured to be 4. 25 mas / yr at 2 ". 47 from the center. we constructed a tilted ellipsoidal shell model by fitting the radio brightness variation of the 5 and 15 ghz vla observations, and making use of the ground - based echelle spectra from bryce & mellema ( 1999 ), to estimate distance. our model has an axial ratio of 1. 56, is inclined to the line of sight by 9. 7 degrees, and exhibits an expansion in the plane of the sky which is 2 / 3 that in the radial direction, leading to a distance of 1. 2 kpc. not all the kinematic data fits this simple model, so the distance must still be regarded as uncertain. based on the recent model atmosphere of crowther et al. ( 2002 ), a distance of 1. 2 kpc implies a stellar luminosity of 4250 l _ sun. the kinematic age of the nebula varies somewhat from region to region ; a good average value is 800 years, while the expansion along the position of the echelle slit gives about 600 years.
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arxiv:astro-ph/0202170
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one of the most complex and devastating disaster scenarios that the u. s. ~ pacific northwest region and the state of oregon faces is a large magnitude cascadia subduction zone earthquake event. the region ' s electrical grid lacks in resilience against the destruction of a megathrust earthquake, a powerful tsunami, hundreds of aftershocks and increased volcanic activity, all of which are highly probable components of this hazard. this research seeks to catalyze further understanding and improvement of resilience. by systematizing power system related experiences of historical earthquakes, and collecting practical and innovative ideas from other regions on how to enhance network design, construction, and operation, important steps are being taken toward a more resilient, earthquake - resistant grid. this paper presents relevant findings in an effort to be an overview and a useful guideline for those who are also working towards greater electrical grid resilience.
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arxiv:2101.07928
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the internal shock model for gamma - ray bursts involves shocks taking place in a relativistic wind with a very inhomogeneous initial distribution of the lorentz factor. we have developed a 1d lagrangian hydrocode to follow the evolution of such a wind and the results we have obtained are compared to those of a simpler model presented in a recent paper ( daigne & mochkovitch 1998 ) where all pressure waves are suppressed in the wind so that shells with different velocities only interact by direct collisions. the detailed hydrodynamical calculation essentially confirms the conclusion of the simple model : the main temporal and spectral properties of gamma - ray bursts can be reproduced by internal shocks in a relativistic wind.
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arxiv:astro-ph/0005193
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recently, a tetraquark mixing framework has been proposed for light mesons and applied more or less successfully to the isovector resonances, $ a _ 0 ( 980 ), a _ 0 ( 1450 ) $, as well as to the isodoublet resonances, $ k ^ * _ 0 ( 800 ), k ^ * _ 0 ( 1430 ) $. in this work, we present a more extensive view on the mixing framework and extend this to the isoscalar resonances, $ f _ 0 ( 500 ) $, $ f _ 0 ( 980 ) $, $ f _ 0 ( 1370 ) $, $ f _ 0 ( 1500 ) $. tetraquarks in this framework can have two spin configurations containing either spin - 0 diquark or spin - 1 diquark and each configuration forms a nonet in flavor space. the two spin configurations are found to mix strongly through the color - spin interactions. their mixtures, which diagonalize the hyperfine masses, can generate the physical resonances constituting the two nonets, which, in fact, coincide roughly with the experimental observation. we identify that $ f _ 0 ( 500 ) $, $ f _ 0 ( 980 ) $ are the isoscalar members in the light nonet, and $ f _ 0 ( 1370 ) $, $ f _ 0 ( 1500 ) $ are the similar members in the heavy nonet. this means that the spin configuration mixing, as it relates the corresponding members in the two nonets, can generate $ f _ 0 ( 500 ), f _ 0 ( 1370 ) $ among the members in light mass, and $ f _ 0 ( 980 ), f _ 0 ( 1500 ) $ in heavy mass. the complication arises because the isoscalar members of each nonet are subject to an additional flavor mixing known as ozi rule so that $ f _ 0 ( 500 ), f _ 0 ( 980 ) $, and similarly $ f _ 0 ( 1370 ), f _ 0 ( 1500 ) $, are the mixture of two isoscalar members belonging to an octet and a singlet in su $ _ f $ ( 3 ). the tetraquark mixing framework including the flavor mixing is tested for the isoscalar resonances in terms of the mass splitting and the fall - apart decay modes.
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arxiv:1711.08213
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due to efficient scaling with electron number n, density functional theory ( dft ) is widely used for studies of large molecules and solids. restriction of an exact mean - field theory to local potential functions has recently been questioned. this review summarizes motivation for extending current dft to include nonlocal one - electron potentials, and proposes methodology for implementation of the theory. the theoretical model, orbital functional theory ( oft ), is shown to be exact in principle for the general n - electron problem. in practice it must depend on a parametrized correlation energy functional. functionals are proposed suitable for short - range coulomb - cusp correlation and for long - range polarization response correlation. a linearized variational cellular method ( lvcm ) is proposed as a common formalism for molecules and solids. implementation of nonlocal potentials is reduced to independent calculations for each inequivalent atomic cell.
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arxiv:cond-mat/0402291
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closed formulae for all gaussian or optimal, 1 - parameter quadrature rules in a compact interval [ a, b ] with non uniform, asymmetric subintervals, arbitrary number of nodes per subinterval for the spline classes $ s _ { 2n, 0 } $ and $ s _ { 2n + 1, 1 } $, i. e. even and odd degree are presented. also rules for the 2 missing spline classes $ s _ { 2n - 1, 0 } $ and $ s _ { 2n, 1 } $ ( the so called 1 / 2 - rules ), i. e. odd and even degree are presented. these quadrature rules are explicit in the sense, that they compute the nodes and their weights in the first / last boundary subinterval and, via a recursion the other nodes / weights, parsing from the first / last subinterval to the middle of the interval. these closed formulae are based on the semi - classical jacobi type orthogonal polynomials.
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arxiv:1908.06199
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we complete the study of the regularity for trudinger ' s equation by proving that weak solutions are h \ " older continuous also in the singular case. the setting is that of a measure space with a doubling non - trivial borel measure supporting a poincar \ ' e inequality. the proof uses the harnack inequality and intrinsic scaling.
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arxiv:1103.1845
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we study the problem of rank aggregation : given a set of ranked lists, we want to form a consensus ranking. furthermore, we consider the case of extreme lists : i. e., only the rank of the best or worst elements are known. we impute missing ranks by the average value and generalise spearman ' s \ rho to extreme ranks. our main contribution is the derivation of a non - parametric estimator for rank aggregation based on multivariate extensions of spearman ' s \ rho, which measures correlation between a set of ranked lists. multivariate spearman ' s \ rho is defined using copulas, and we show that the geometric mean of normalised ranks maximises multivariate correlation. motivated by this, we propose a weighted geometric mean approach for learning to rank which has a closed form least squares solution. when only the best or worst elements of a ranked list are known, we impute the missing ranks by the average value, allowing us to apply spearman ' s \ rho. finally, we demonstrate good performance on the rank aggregation benchmarks mq2007 and mq2008.
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arxiv:1410.4391
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dynamic contrast - enhanced magnetic resonance imaging ( dce - mri ) is used to study microvascular structure and tissue perfusion. in dce - mri a bolus of gadolinium based contrast agent is injected into the blood stream and spatiotemporal changes induced by the contrast agent flow are estimated from a time series of mri data. sufficient time resolution can often only be obtained by using an imaging protocol which produces undersampled data for each image in the time series. this has led to the popularity of compressed sensing based image reconstruction approaches, where all the images in the time series are reconstructed simultaneously, and temporal coupling between the images is introduced into the problem by a sparsity promoting regularization functional. we propose the use of huber penalty for temporal regularization in dce - mri, and compare it to total variation, total generalized variation and smoothness based temporal regularization models. we also study the effect of spatial regularization to the reconstruction and compare the reconstruction accuracy with different temporal resolutions due to varying undersampling. the approaches are tested using simulated and experimental radial golden angle dce - mri data from a rat brain specimen. the results indicate that huber regularization produces similar reconstruction accuracy with the total variation based models, but the computation times are significantly faster.
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arxiv:2003.08652
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bosonic codes offer a hardware - efficient approach to encoding and protecting quantum information with a single continuous - variable bosonic system. in this paper, we introduce a new universal quantum gate set composed of only one type of gate element, which we call the quantum lattice gate, to engineer bosonic code states for fault - tolerant quantum computing. we develop a systematic framework for code state engineering based on the floquet hamiltonian engineering, where the target hamiltonian is constructed directly from the given target state ( s ). we apply our method to three basic code state engineering processes, including single code state preparation, code space embedding and code space transformation. we explore the application of our method to automatic quantum error correction against single - photon loss with four - legged cat codes. our proposal is particularly well - suited for superconducting circuit architectures with josephson junctions, where the full nonlinearity of josephson junction potential is harnessed as a quantum resource and the quantum lattice gate can be implemented on a sub - nanosecond timescale.
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arxiv:2410.17069
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ga for mn substitution in multiferroic tbmno $ _ { 3 } $ has been performed in order to study the influence of mn - magnetic ordering on the tb - magnetic sublattice. complete characterization of tbmn $ _ { 1 - x } $ ga $ _ x $ o $ _ { 3 } $ ( $ x $ = 0, 0. 04, 0. 1 ) samples, including magnetization, impedance spectroscopy, and x - ray resonant scattering and neutron diffraction on powder and single crystals has been carried out. we found that keeping the same crystal structure for all compositions, ga for mn substitution leads to the linear decrease of $ t _ { \ rm n } ^ { \ rm mn } $ and $ \ tau ^ { \ rm mn } $, reflecting the reduction of the exchange interactions strength $ j _ { \ rm mn - mn } $ and the change of the mn - o - mn bond angles. at the same time, a strong suppression of both the induced and the separate tb - magnetic ordering has been observed. this behavior unambiguously prove that the exchange fields $ j _ { \ rm mn - tb } $ have a strong influence on the tb - magnetic ordering in the full temperature range below $ t _ { \ rm n } ^ { \ rm mn } $ and actually stabilize the tb - magnetic ground state.
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arxiv:0909.5082
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given a topological property $ \ mathcal { p } $, a space $ x $ is called star - $ \ mathcal { p } $ if for any open cover $ \ mathcal { u } $ of the space $ x $, there exists a set $ y \ subseteq x $ with property $ \ mathcal { p } $ such that $ st ( y, \ mathcal { u } ) = x $ ; the set $ y $ is called a star kernel of the cover $ \ mathcal { u } $. in this paper, we introduce and study spaces with star kernel menger, that is, star menger spaces. some examples are given to show the relationship with some other related properties studied previously, and the behaviour of the star menger property with respect to subspaces, products, continuous images and preimages are investigated. additionally, some comments on the star selection theory are given. particularly, some questions posed by song within this theory are addressed. finally, several new properties are introduced as well as some general questions on them are posed.
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arxiv:2301.09551
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the coupling of the spin of electrons to their motional state lies at the heart of recently discovered topological phases of matter. here we create and detect spin - orbit coupling in an atomic fermi gas, a highly controllable form of quantum degenerate matter. we reveal the spin - orbit gap via spin - injection spectroscopy, which characterizes the energy - momentum dispersion and spin composition of the quantum states. for energies within the spin - orbit gap, the system acts as a spin diode. to fully inhibit transport, we open an additional spin gap, thereby creating a spin - orbit coupled lattice whose spinful band structure we probe. in the presence of s - wave interactions, such systems should display induced p - wave pairing, topological superfluidity, and majorana edge states.
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arxiv:1205.3483
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the fast and accurate prediction of unsteady flow becomes a serious challenge in fluid dynamics, due to the high - dimensional and nonlinear characteristics. a novel hybrid deep neural network ( dnn ) architecture was designed to capture the unsteady flow spatio - temporal features directly from the high - dimensional unsteady flow fields. the hybrid deep neural network is constituted by the convolutional neural network ( cnn ), convolutional long short term memory neural network ( convlstm ) and deconvolutional neural network ( decnn ). the flow around a cylinder at various reynolds numbers and the flow around an airfoil at higher reynolds number are carried out to establish the datasets used to train the networks separately. the trained hybrid dnns were then tested by the prediction of the flow fields at future occasions. the predicted flow fields using the trained hybrid dnns are in good agreement with the flow fields calculated directly by the computational fluid dynamic solver.
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arxiv:1908.00294
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as an emerging communication auxiliary technology, reconfigurable intelligent surface ( ris ) is expected to play a significant role in the upcoming 6g networks. due to its total reflection characteristics, it is challenging to implement conventional channel estimation algorithms. this work focuses on ris - assisted mimo communications. although many algorithms have been proposed to address this issue, there are still ample opportunities for improvement in terms of estimation accuracy, complexity, and applicability. to fully exploit the structured sparsity of the multiple - input - multiple - output ( mimo ) channels, we propose a new channel estimation algorithm called unitary approximate message passing sparse bayesian learning with partial common support identification ( uampsbl - pci ). thanks to the mechanism of pci and the use of uamp, the proposed algorithm has a lower complexity while delivering enhanced performance relative to existing channel estimation algorithms. extensive simulations demonstrate its excellent performance in various environments.
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arxiv:2308.01425
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the rapid development of text - to - image ( t2i ) generation approaches has attracted extensive interest in evaluating the quality of generated images, leading to the development of various quality assessment methods for general - purpose t2i outputs. however, existing image quality assessment ( iqa ) methods are limited to providing global quality scores, failing to deliver fine - grained perceptual evaluations for structurally complex subjects like humans, which is a critical challenge considering the frequent anatomical and textural distortions in ai - generated human images ( aghis ). to address this gap, we introduce aghi - qa, the first large - scale benchmark specifically designed for quality assessment of aghis. the dataset comprises 4, 000 images generated from 400 carefully crafted text prompts using 10 state of - the - art t2i models. we conduct a systematic subjective study to collect multidimensional annotations, including perceptual quality scores, text - image correspondence scores, visible and distorted body part labels. based on aghi - qa, we evaluate the strengths and weaknesses of current t2i methods in generating human images from multiple dimensions. furthermore, we propose aghi - assessor, a novel quality metric that integrates the large multimodal model ( lmm ) with domain - specific human features for precise quality prediction and identification of visible and distorted body parts in aghis. extensive experimental results demonstrate that aghi - assessor showcases state - of - the - art performance, significantly outperforming existing iqa methods in multidimensional quality assessment and surpassing leading lmms in detecting structural distortions in aghis.
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arxiv:2504.21308
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high - precision atomic structure calculations require accurate modelling of electronic correlations typically addressed via the configuration interaction ( ci ) problem on a multiconfiguration wave function expansion. the latter can easily become challenging or infeasibly large even for advanced supercomputers. here we develop a deep - learning approach which allows to preselect the most relevant configurations out of large ci basis sets until the targeted energy precision is achieved. the large ci computation is thereby replaced by a series of smaller ones performed on an iteratively expanding basis subset managed by a neural network. while dense architectures as used in quantum chemistry fail, we show that a convolutional neural network naturally accounts for the physical structure of the basis set and allows for robust and accurate ci calculations. the method was benchmarked on basis sets of moderate size allowing for the direct ci calculation, and further demonstrated on prohibitively large sets where the direct computation is not possible.
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arxiv:2209.05867
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we consider in this paper a class of semi - continuous quadratic programming problems which arises in many real - world applications such as production planning, portfolio selection and subset selection in regression. we propose a lift - and - convexification approach to derive an equivalent reformulation of the original problem. this lift - and - convexification approach lifts the quadratic term involving $ x $ only in the original objective function $ f ( x, y ) $ to a quadratic function of both $ x $ and $ y $ and convexifies this equivalent objective function. while the continuous relaxation of our new reformulation attains the same tight bound as achieved by the continuous relaxation of the well known perspective reformulation, the new reformulation also retains the linearly constrained quadratic programming structure of the original mix - integer problem. this prominent feature improves the performance of branch - and - bound algorithms by providing the same tightness at the root node as the state - of - the - art perspective reformulation and offering much faster processing time at children nodes. we further combine the lift - and - convexification approach and the quadratic convex reformulation approach in the literature to form an even tighter reformulation. promising results from our computational tests in both portfolio selection and subset selection problems numerically verify the benefits from these theoretical features of our new reformulations.
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arxiv:1507.05708
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we study the asymptotic quantization error of order $ r $ for markov - type measures $ \ mu $ on a class of ratio - specified graph directed fractals. we show that the quantization dimension of $ \ mu $ exists and determine its exact value $ s _ { r } $ in terms of spectral radius of a related matrix. we prove that the $ s _ { r } $ - dimensional lower quantization coefficient of $ \ mu $ is always positive. moreover, inspired by mauldin - williams ' s work on the hausdorff measure of graph directed fractals, we establish a necessary and sufficient condition for the $ s _ { r } $ - dimensional upper quantization coefficient of $ \ mu $ to be finite.
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arxiv:1406.3257
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a population of neurons typically exhibits a broad diversity of responses to sensory inputs. the intuitive notion of functional classification is that cells can be clustered so that most of the diversity is captured in the identity of the clusters rather than by individuals within clusters. we show how this intuition can be made precise using information theory, without any need to introduce a metric on the space of stimuli or responses. applied to the retinal ganglion cells of the salamander, this approach recovers classical results, but also provides clear evidence for subclasses beyond those identified previously. further, we find that each of the ganglion cells is functionally unique, and that even within the same subclass only a few spikes are needed to reliably distinguish between cells.
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arxiv:physics/0212114
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this paper investigates the observability of one of the most commonly used equivalent circuit models ( ecms ) for lithium - ion batteries and presents a method to estimate the state of charge ( soc ) in the presence of sensor biases, highlighting the importance of observability analysis for choosing appropriate state estimation algorithms. using a differential geometric approach, necessary and sufficient conditions for the nonlinear ecm to be observable are derived and are shown to be different from the conditions for the observability of the linearised model. it is then demonstrated that biases in the measurements, due to sensor ageing or calibration errors, can be estimated by applying a nonlinear kalman filter to an augmented model where the biases are incorporated into the state vector. experiments are carried out on a lithium - ion pouch cell and three types of nonlinear filters, the first - order extended kalman filter ( ekf ), the second - order ekf and the unscented kalman filter ( ukf ) are applied using experimental data. the different performances of the filters are explained from the point of view of observability.
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arxiv:1510.06553
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the fusion of visible light and infrared images has garnered significant attention in the field of imaging due to its pivotal role in various applications, including surveillance, remote sensing, and medical imaging. therefore, this paper introduces a novel fusion framework using res2net architecture, capturing features across diverse receptive fields and scales for effective extraction of global and local features. our methodology is structured into three fundamental components : the first part involves the res2net - based encoder, followed by the second part, which encompasses the fusion layer, and finally, the third part, which comprises the decoder. the encoder based on res2net is utilized for extracting multi - scale features from the input image. simultaneously, with a single image as input, we introduce a pioneering training strategy tailored for a res2net - based encoder. we further enhance the fusion process with a novel strategy based on the attention model, ensuring precise reconstruction by the decoder for the fused image. experimental results unequivocally showcase our method ' s unparalleled fusion performance, surpassing existing techniques, as evidenced by rigorous subjective and objective evaluations.
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arxiv:2112.14540
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we perform an x - ray spectral analysis of the brightest and cleanest bare agn known so far, ark 120, in order to determine the process ( es ) at work in the vicinity of the smbh. we present spectral analysis of data from an extensive campaign observing ark 120 in x - rays with xmm - newton ( 4 $ \ times $ 120 ks, 2014 march 18 - 24 ), and nustar ( 65. 5 ks, 2014 march 22 ). during this very deep x - ray campaign, the source was caught in a high flux state similar to the earlier 2003 xmm - newton observation, and about twice as bright as the lower - flux observation in 2013. the spectral analysis confirms the " softer when brighter " behaviour of ark 120. the four xmm - newton / pn spectra are characterized by the presence of a prominent soft x - ray excess and a significant fek $ \ alpha $ complex. the continuum is very similar above about 3 kev, while significant variability is present for the soft x - ray excess. we find that relativistic reflection from a constant - density, flat accretion disk cannot simultaneously produce the soft excess, broad fek $ \ alpha $ complex, and hard x - ray excess. instead, comptonization reproduces the broadband ( 0. 3 - 79 kev ) continuum well, together with a contribution from a mildly relativistic disk reflection spectrum. during this 2014 observational campaign, the soft x - ray spectrum of ark 120 below $ \ sim $ 0. 5 kev was found to be dominated by comptonization of seed photons from the disk by a warm ( $ kt _ { \ rm e } $ $ \ sim $ 0. 5 kev ), optically - thick corona ( $ \ tau $ $ \ sim $ 9 ). above this energy, the x - ray spectrum becomes dominated by comptonization from electrons in a hot optically thin corona, while the broad fek $ \ alpha $ line and the mild compton hump result from reflection off the disk at several tens of gravitational radii.
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arxiv:1707.08907
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the ability to resolve all processes which drive galaxy formation is one of the most fundamental goals in extragalactic astronomy. while star formation rates and the merger history are now measured with increasingly high certainty, the role of gas accretion from the intergalactic medium in supplying gas for star formation still remains largely unknown. we present in this paper indirect evidence for the accretion of gas into massive galaxies with initial stellar masses m _ * > 10 ^ { 11 } m _ sol and following the same merger adjusted co - moving number density at lower redshifts during the epoch 1. 5 < z < 3, using results from the goods nicmos survey ( gns ). we show that the measured gas mass fractions of these massive galaxies are inconsistent with the observed star formation history for the same galaxy population. we further demonstrate that this additional gas mass cannot be accounted for by cold gas delivered through minor and major mergers. we also consider the effects of gas outflows and gas recycling due to stellar evolution in these calculations. we argue that to sustain star formation at the observed rates there must be additional methods for increasing the cold gas mass, and that the likeliest method for establishing this supply of gas is by accretion from the intergalactic medium. we calculate that the average gas mass accretion rate into these massive galaxies between 1. 5 < z < 3. 0, is \ dot { m } = 96 + / - 19 m _ sol / yr after accounting for outflowing gas. we show that during this epoch, and for these very massive galaxies, 49 + / - 20 % of baryonic mass assembly is a result of gas accretion and unresolved mergers. however, 66 + / - 20 % of all star formation in this epoch is the result of gas accretion. this reveals that for the most massive galaxies at 1. 5 < z < 3 gas accretion is the dominant method for instigating new stellar mass assembly.
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arxiv:1206.6995
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due to the lack of long term pulsed emission in quiescence and the strong timing noise, it is impossible to directly measure the braking index $ n $ of a magnetar. based on the estimated ages of their potentially associated supernova remnants ( snrs ), we estimate the values of the mean braking indices of eight magnetars with snrs, and find that they cluster in a range of $ 1 \ sim $ 42. five magnetars have smaller mean braking indices of $ 1 < n < 3 $, and we interpret them within a combination of magneto - dipole radiation and wind aided braking, while the larger mean braking indices of $ n > 3 $ for other three magnetars are attributed to the decay of external braking torque, which might be caused by magnetic field decay. we estimate the possible wind luminosities for the magnetars with $ 1 < n < 3 $, and the dipolar magnetic field decay rates for the magnetars with $ n > 3 $ within the updated magneto - thermal evolution models. although the constrained range of the magnetars ' braking indices is tentative, due to the uncertainties in the snr ages, which come from distance uncertainties and the unknown conditions of the expanding shells, our method provides an effective way to constrain the magnetars ' braking indices if the measurements of the snrs ' ages are reliable, which can be improved by future observations.
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arxiv:1505.07013
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in order to solve the problems of waveform distortion and signal delay by many physical and electrical systems with linear low - pass transfer characteristics with multiple complex poles, a general digital - signal - processing ( dsp ) - based method of real - time recovery of the original source waveform from the distorted output waveform is proposed. from the convolution kernel representation of a multiple - pole low - pass transfer function with an arbitrary denominator polynomial with real valued coefficients, it is shown that the source waveform can be accurately recovered in real time using a particular moving average algorithm with real - valued dsp computations only, even though some or all of the poles are complex. the proposed digital signal recovery method is dc - accurate and unaffected by initial conditions, transient signals, and resonant amplitude enhancement. the noise characteristics of the data recovery shows inverse of the low - pass filter characteristics. this method can be applied to most sensors and amplifiers operating close to their frequency response limits or around their resonance frequencies to accurately deconvolute the multiple - pole characteristics and to improve the overall performances of data acquisition systems and digital feedback control systems.
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arxiv:1807.07105
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innovative machine learning techniques have facilitated the inverse design of photonic structures for numerous practical applications. nevertheless, within these approaches, the quantity of data and the initial data distribution are paramount for the discovery of highly efficient photonic devices. these devices often require simulated data ranging from thousands to several hundred thousand data points. this issue has consistently posed a major hurdle in machine learning - based photonic design problems. therefore, we propose a novel data augmentation algorithm grounded in the adjoint method, capable of generating more than 300 times the amount of original data while enhancing device efficiency. the adjoint method forecasts changes in the figure of merit ( fom ) resulting from structural perturbations, requiring only two full - wave maxwell simulations for this prediction. by leveraging the adjoint gradient values, we can augment and label several thousand new data points without any additional computations. furthermore, the augmented data generated by the proposed algorithm displays significantly improved foms owing to the precise fom change predictions enabled by the adjoint gradients. we apply this algorithm to a multi - layered metalens design problem and demonstrate that it consequently exhibits a 343 - fold increase in data generation efficiency. after incorporating the proposed algorithm into a generative adversarial network ( gan ), the optimized metalens exhibits a maximum focusing efficiency of 92. 93 %, comparable to the theoretical upper bound ( 93. 80 % ).
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arxiv:2310.19291
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we paralinearize the muskat equation to extract an explicit parabolic evolution equation having a compact form. this result is applied to give a simple proof of the local well - posedness of the cauchy problem for rough initial data, in homogeneous sobolev spaces $ \ dot { h } ^ 1 ( \ mathbb { r } ) \ cap \ dot { h } ^ s ( \ mathbb { r } ) $ with $ s > 3 / 2 $. this paper is essentially self - contained and does not rely on general results from paradifferential calculus.
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arxiv:1907.02138
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it has been shown in [ frauenfelder, 2023 ] that the bounded component of the energy surface of the planer stark problem after the levi - civita transformation are concave toric domains. in this paper, we present a different approach on the problem of determining concave toric domains in a family of integrable natural mechanical problems in the plane based on the computation of action - variables. we give criteria on the potentials for the bounded components of the energy hypersurfaces to be concave toric domains and apply these criteria to a class of problems.
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arxiv:2311.08912
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wireless key generation holds significant promise for establishing cryptographic keys in next - gen internet of vehicles ( iov ) systems. however, existing approaches often face inefficiencies and performance limitations caused by frequent channel probing and ineffective quantization. to address these challenges, this paper introduces llmkey, a novel key generation system designed to enhance efficiency and security. we identify excessive channel probing and suboptimal quantization as critical bottlenecks in current methods. to mitigate these issues, we propose an innovative large language model ( llm ) - based channel probing technique that leverages the capabilities of llms to reduce probing rounds while preserving crucial channel information. instead of conventional quantization, llmkey adopts a perturbed compressed sensing - based key delivery mechanism, improving both robustness and security. extensive evaluations are conducted in four real - world scenarios, encompassing v2i ( vehicle - to - infrastructure ) and v2v ( vehicle - to - vehicle ) settings in both urban and rural environments. the results show that llmkey achieves an average key agreement rate of 98. 78 \ %, highlighting its effectiveness and reliability across diverse conditions.
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arxiv:2502.16199
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in this work, two approaches for simulating x - ray absorption ( xa ) spectra with the complete active space self - consistent field ( casscf ) linear response ( lr ) method are introduced. the first approach employs the well - known core - valence separation ( cvs ) approximation, which is predominantly used by many other electronic structure methods for simulating x - ray spectra. the second ansatz uses the harmonic davidson algorithm ( da ) for finding interior eigenvalues that lie close to a target excitation energy shift and virtually solves a shifted - and - inverted ( s & i ) generalized eigenvalue problem. our implementations of these davidson - type algorithms for core spectroscopies converge as rapidly as the standard da for valence excitations. it is shown in a proof - of - principle application to the manganese atom that the additional errors for excitations energies introduced by the cvs approximation compared to the exact s & i approach are negligible for k - edges, but become larger than the methodological error of the casscf lr method when computing m - edges. we could also demonstrate that, in case of large active - space k - edge calculations, the computational savings of the cvs approximation are huge as the configuration part of the response vectors is completely neglected. when simulating the oxygen k - edge xa spectrum of the permanganate ion, casscf lr showed a better agreement with the experimental spectrum than the cas - ci and nevpt2 methods, however, the order of the two close - together pre - edge peaks seems to be inverted.
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arxiv:2004.05845
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models for genome - wide prediction and association studies usually target a single phenotypic trait. however, in animal and plant genetics it is common to record information on multiple phenotypes for each individual that will be genotyped. modeling traits individually disregards the fact that they are most likely associated due to pleiotropy and shared biological basis, thus providing only a partial, confounded view of genetic effects and phenotypic interactions. in this paper we use data from a multiparent advanced generation inter - cross ( magic ) winter wheat population to explore bayesian networks as a convenient and interpretable framework for the simultaneous modeling of multiple quantitative traits. we show that they are equivalent to multivariate genetic best linear unbiased prediction ( gblup ), and that they are competitive with single - trait elastic net and single - trait gblup in predictive performance. finally, we discuss their relationship with other additive - effects models and their advantages in inference and interpretation. magic populations provide an ideal setting for this kind of investigation because the very low population structure and large sample size result in predictive models with good power and limited confounding due to relatedness.
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arxiv:1402.2905
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in this paper, we derive the cramer - rao bound ( crb ) for blind channel estimation in redundant block transmission systems, a lower bound for the mean squared error of any blind channel estimators. the derived crb is valid for any full - rank linear redundant precoder, including both zero - padded ( zp ) and cyclic - prefixed ( cp ) precoders. a simple form of crbs for multiple complex parameters is also derived and presented which facilitates the crb derivation of the problem of interest. a comparison is made between the derived crbs and performances of existing subspace - based blind channel estimators for both cp and zp systems. numerical results show that there is still some room for performance improvement of blind channel estimators.
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arxiv:1102.1231
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the evolution of non - potential perturbations to a current - free magnetic x - point configuration is studied, taking into account electron inertial effects as well as resistivity. electron inertia is shown to have a negligible effect on the evolution of the system whenever the collisionless skin depth is less than the resistive scale length. non - potential magnetic field energy in this resistive mhd limit initially reaches equipartition with flow energy, in accordance with ideal mhd, and is then dissipated extremely rapidly, on an alfvenic timescale that is essentially independent of lundquist number. in agreement with resistive mhd results obtained by previous authors, the magnetic field energy and kinetic energy are then observed to decay on a longer timescale and exhibit oscillatory behavior, reflecting the existence of discrete normal modes with finite real frequency. when the collisionless skin depth exceeds the resistive scale length, the system again evolves initially according to ideal mhd. at the end of this ideal phase, the field energy decays typically on an alfvenic timescale, while the kinetic energy ( which is equally partitioned between ions and electrons in this case ) is dissipated on the electron collision timescale. the oscillatory decay in the energy observed in the resistive case is absent, but short wavelength structures appear in the field and velocity profiles, suggesting the possibility of particle acceleration in oppositely - directed current channels. the model provides a possible framework for interpreting observations of energy release and particle acceleration on timescales down to less than a second in the impulsive phase of solar flares.
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arxiv:astro-ph/0401573
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we investigate the parity - violating effects in primordial gravitational waves ( gws ) due to null energy condition ( nec ) violation in two very early universe scenarios : bounce - inflation and intermediate nec violation during inflation. in both scenarios, we numerically solve the power spectra of parity - violating primordial gws generated by coupling the background field and the spectator field with the nieh - yan term, respectively. we find that the background field can significantly enhance parity - violating effects at scales corresponding to the maximum of the gw power spectra. in contrast, the parity - violating effects produced by the spectator show significantly weaker observability even if the coupling constant is large. therefore, in nec - violating scenarios, the significant observable parity - violating effects in primordial gws primarily arise from the physics directly related to nec violation. this result highlights the potential of primordial gws as crucial tools for exploring nec - violating and parity - violating physics.
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arxiv:2406.16549
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this paper proposes a computationally efficient algorithm to address the full - waveform inversion ( fwi ) problem with a total variation ( tv ) constraint, designed to accurately reconstruct subsurface properties from seismic data. fwi, as an ill - posed inverse problem, requires effective regularizations or constraints to ensure accurate and stable solutions. among these, the tv constraint is widely known as a powerful prior for modeling the piecewise smooth structure of subsurface properties. however, solving the optimization problem is challenging because of the nonlinear observation process combined with the non - smoothness of the tv constraint. conventional methods rely on inner loops and / or approximations, which lead to high computational cost and / or inappropriate solutions. to address these limitations, we develop a novel algorithm based on a primal - dual splitting method, achieving computational efficiency by eliminating inner loops and ensuring high accuracy by avoiding approximations. we also demonstrate the effectiveness of the proposed method through experiments using the seg / eage salt and overthrust models. the source code will be available at https : / / www. mdi. c. titech. ac. jp / publications / fwiwtv.
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arxiv:2501.08210
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semi - supervised learning ( ssl ) has shown notable potential in relieving the heavy demand of dense prediction tasks on large - scale well - annotated datasets, especially for the challenging multi - organ segmentation ( mos ). however, the prevailing class - imbalance problem in mos, caused by the substantial variations in organ size, exacerbates the learning difficulty of the ssl network. to alleviate this issue, we present a two - phase semi - supervised network ( bsr - net ) with balanced subclass regularization for mos. concretely, in phase i, we introduce a class - balanced subclass generation strategy based on balanced clustering to effectively generate multiple balanced subclasses from original biased ones according to their pixel proportions. then, in phase ii, we design an auxiliary subclass segmentation ( scs ) task within the multi - task framework of the main mos task. the scs task contributes a balanced subclass regularization to the main mos task and transfers unbiased knowledge to the mos network, thus alleviating the influence of the class - imbalance problem. extensive experiments conducted on two publicly available datasets, i. e., the miccai flare 2022 dataset and the word dataset, verify the superior performance of our method compared with other methods.
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arxiv:2408.14047
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we develop a microscopic theory of the electronic nematic phase proximate to an isotropic fermi liquid in both two and three dimensions. explicit expressions are obtained for the small amplitude collective excitations in the ordered state ; remarkably, the nematic goldstone mode ( the directorwave ) is overdamped except along special directions dictated by symmetry. at the quantum critical point we find a dynamical exponent of $ z = 3 $, implying stability of the gaussian fixed point. the leading perturbative effect of the overdamped goldstone modes leads to a breakdown of fermi liquid theory in the nematic phase and to strongly angle dependent electronic self energies around the fermi surface. other metallic liquid crystal phases, { \ it e. g. } a quantum hexatic, behave analogously.
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arxiv:cond-mat/0102093
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quantum non - cloning theorem and a thought experiment are discussed for charged black holes whose global structure exhibits an event and a cauchy horizon. we take reissner - norstr \ " { o } m black holes and two - dimensional dilaton black holes as concrete examples. the results show that the quantum non - cloning theorem and the black hole complementarity are far from consistent inside the inner horizon. the relevance of this work to non - local measurements is briefly discussed.
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arxiv:gr-qc/0503094
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we report hyperpolarization of the electronic spins associated with substitutional nitrogen defects in bulk diamond crystal. hyperpolarization is achieved by optical pumping of nitrogen vacancy centers followed by rapid cross relaxation at the energy level matching condition in a 51 mt bias field. the maximum observed donor spin polarization is 0. 9 \ % corresponding to an enhancement by 25 compared to the thermal boltzmann polarization. a further accumulation of polarization is impeded by an anomalous optical saturation effect that we attribute to charge state conversion processes. hyperpolarized nitrogen donors may form a useful resource for increasing the efficiency of diamond - based dynamic nuclear polarization devices.
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arxiv:1612.08104
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we present new superalgebra for $ \ mathcal { n } = 2 $ $ d = 3, 4 $ supergravity theory endowed with the $ u ( 1 ) $ generator. the superalgebra is rooted in the so - called soroka - soroka algebra and spanned by the lorentz $ j _ { ab } $ and lorentz - like $ z _ { ab } $, translation $ p _ a $ and $ t $ generators, as well as two supercharges $ q ^ i _ \ alpha $. it is the only possible realization for a given generator content. we construct a corresponding 3d chern - simons supergravity realization of the superalgebra and discuss its relevance.
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arxiv:2205.05921
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in 2018, the star collaboration collected data from $ _ { 44 } ^ { 96 } ru + _ { 44 } ^ { 96 } ru $ and $ _ { 40 } ^ { 96 } zr + _ { 40 } ^ { 96 } zr $ at $ \ sqrt { s _ { nn } } = 200 $ gev to search for the presence of the chiral magnetic effect in collisions of nuclei. the isobar collision species alternated frequently between $ _ { 44 } ^ { 96 } ru + _ { 44 } ^ { 96 } ru $ and $ _ { 40 } ^ { 96 } zr + _ { 40 } ^ { 96 } zr $. in order to conduct blind analyses of studies related to the chiral magnetic effect in these isobar data, star developed a three - step blind analysis procedure. analysts are initially provided a " reference sample " of data, comprised of a mix of events from the two species, the order of which respects time - dependent changes in run conditions. after tuning analysis codes and performing time - dependent quality assurance on the reference sample, analysts are provided a species - blind sample suitable for calculating efficiencies and corrections for individual $ \ approx30 $ - minute data - taking runs. for this sample, species - specific information is disguised, but individual output files contain data from a single isobar species. only run - by - run corrections and code alteration subsequent to these corrections are allowed at this stage. following these modifications, the " frozen " code is passed over the fully un - blind data, completing the blind analysis. as a check of the feasibility of the blind analysis procedure, analysts completed a " mock data challenge, " analyzing data from $ au + au $ collisions at $ \ sqrt { s _ { nn } } = 27 $ gev, collected in 2018. the $ au + au $ data were prepared in the same manner intended for the isobar blind data. the details of the blind analysis procedure and results from the mock data challenge are presented.
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arxiv:1911.00596
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we compute the boundary entropy for bond percolation on the square lattice in the presence of a boundary loop weight, and prove explicit and exact expressions on a strip and on a cylinder of size $ l $. for the cylinder we provide a rigorous asymptotic analysis which allows for the computation of finite - size corrections to arbitrary order. for the strip we provide exact expressions that have been verified using high - precision numerical analysis. our rigorous and exact results corroborate an argument based on conformal field theory, in particular concerning universal logarithmic corrections for the case of the strip due to the presence of corners in the geometry. we furthermore observe a crossover at a special value of the boundary loop weight.
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arxiv:1610.04006
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amplification of magnetic field due to kinematic turbulent dynamo action is studied in the regime of small magnetic prandtl numbers. such a regime is relevant for planets and stars interiors, as well as for liquid metal laboratory experiments. a comprehensive analysis based on the kazantsev - kraichnan model is reported, which establishes the dynamo threshold and the dynamo growth rates for varying kinetic helicity of turbulent fluctuations. it is proposed that in contrast with the case of large magnetic prandtl numbers, the kinematic dynamo action at small magnetic prandtl numbers is significantly affected by kinetic helicity, and it can be made quite efficient with an appropriate choice of the helicity spectrum.
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arxiv:1011.0202
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existing joint optic disc and cup segmentation approaches are developed either in cartesian or polar coordinate system. however, due to the subtle optic cup, the contextual information exploited from the single domain even by the prevailing cnns is still insufficient. in this paper, we propose a novel segmentation approach, named cartesian - polar dual - domain network ( ddnet ), which for the first time considers the complementary of the cartesian domain and the polar domain. we propose a two - branch of domain feature encoder and learn translation equivariant representations on rectilinear grid from cartesian domain and rotation equivariant representations on polar grid from polar domain parallelly. to fuse the features on two different grids, we propose a dual - domain fusion module. this module builds the correspondence between two grids by the differentiable polar transform layer and learns the feature importance across two domains in element - wise to enhance the expressive capability. finally, the decoder aggregates the fused features from low - level to high - level and makes dense predictions. we validate the state - of - the - art segmentation performances of our ddnet on the public dataset origa. according to the segmentation masks, we estimate the commonly used clinical measure for glaucoma, i. e., the vertical cup - to - disc ratio. the low cup - to - disc ratio estimation error demonstrates the potential application in glaucoma screening.
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arxiv:1904.08773
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a theorem of kleitman states that a collection of binary vectors with diameter d has cardinality at most that of a hamming ball of radius d / 2. in this paper, we give a q - analog of it.
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arxiv:2503.19239
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we consider the calculation of scattering amplitudes in field theories dual to lifshitz spacetimes. these amplitudes provide an interesting probe of the ir structure of the field theory ; our aim is to use them to explore the observable consequences of the singularity in the spacetime. we assume the amplitudes can be related by t - duality to a wilson loop, as in the ads case, and determine the bulk minimal surfaces for the simplest cusp wilson loop. we use this to determine the leading ir singularity in the amplitude. we find there is a stronger ir singularity for z > 1 than for z = 1, with a coefficient which vanishes as z goes to 1.
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arxiv:1406.6389
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federated multi - modal learning ( fmml ) is an emerging field that integrates information from different modalities in federated learning to improve the learning performance. in this letter, we develop a parameter scheduling scheme to improve personalized performance and communication efficiency in personalized fmml, considering the non - independent and nonidentically distributed ( non - iid ) data along with the modality heterogeneity. specifically, a learning - based approach is utilized to obtain the aggregation coefficients for parameters of different modalities on distinct devices. based on the aggregation coefficients and channel state, a subset of parameters is scheduled to be uploaded to a server for each modality. experimental results show that the proposed algorithm can effectively improve the personalized performance of fmml.
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arxiv:2406.07915
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srinivasa ramanujan aiyangar ( 22 december 1887 β 26 april 1920 ) was an indian mathematician. often regarded as one of the greatest mathematicians of all time, though he had almost no formal training in pure mathematics, he made substantial contributions to mathematical analysis, number theory, infinite series, and continued fractions, including solutions to mathematical problems then considered unsolvable. ramanujan initially developed his own mathematical research in isolation. according to hans eysenck, " he tried to interest the leading professional mathematicians in his work, but failed for the most part. what he had to show them was too novel, too unfamiliar, and additionally presented in unusual ways ; they could not be bothered ". seeking mathematicians who could better understand his work, in 1913 he began a mail correspondence with the english mathematician g. h. hardy at the university of cambridge, england. recognising ramanujan ' s work as extraordinary, hardy arranged for him to travel to cambridge. in his notes, hardy commented that ramanujan had produced groundbreaking new theorems, including some that " defeated me completely ; i had never seen anything in the least like them before ", and some recently proven but highly advanced results. during his short life, ramanujan independently compiled nearly 3, 900 results ( mostly identities and equations ). many were completely novel ; his original and highly unconventional results, such as the ramanujan prime, the ramanujan theta function, partition formulae and mock theta functions, have opened entire new areas of work and inspired further research. of his thousands of results, most have been proven correct. the ramanujan journal, a scientific journal, was established to publish work in all areas of mathematics influenced by ramanujan, and his notebooks β containing summaries of his published and unpublished results β have been analysed and studied for decades since his death as a source of new mathematical ideas. as late as 2012, researchers continued to discover that mere comments in his writings about " simple properties " and " similar outputs " for certain findings were themselves profound and subtle number theory results that remained unsuspected until nearly a century after his death. he became one of the youngest fellows of the royal society and only the second indian member, and the first indian to be elected a fellow of trinity college, cambridge. in 1919, ill health β now believed to have been hepatic amoebiasis ( a complication from episodes of dysentery many years previously ) β compelled ramanujan ' s
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https://en.wikipedia.org/wiki/Srinivasa_Ramanujan
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many practical prediction algorithms represent inputs in euclidean space and replace the discrete 0 / 1 classification loss with a real - valued surrogate loss, effectively reducing classification tasks to stochastic optimization. in this paper, we investigate the expressivity of such reductions in terms of key resources, including dimension and the role of randomness. we establish bounds on the minimum euclidean dimension $ d $ needed to reduce a concept class with vc dimension $ d $ to a stochastic convex optimization ( sco ) problem in $ \ mathbb { r } ^ d $, formally addressing the intuitive interpretation of the vc dimension as the number of parameters needed to learn the class. to achieve this, we develop a generalization of the borsuk - ulam theorem that combines the classical topological approach with convexity considerations. perhaps surprisingly, we show that, in some cases, the number of parameters $ d $ must be exponentially larger than the vc dimension $ d $, even if the reduction is only slightly non - trivial. we also present natural classification tasks that can be represented in much smaller dimensions by leveraging randomness, as seen in techniques like random initialization. this result resolves an open question posed by kamath, montasser, and srebro ( colt 2020 ). our findings introduce new variants of \ emph { dimension complexity } ( also known as \ emph { sign - rank } ), a well - studied parameter in learning and complexity theory. specifically, we define an approximate version of sign - rank and another variant that captures the minimum dimension required for a reduction to sco. we also propose several open questions and directions for future research.
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arxiv:2411.10784
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by exploiting the relation between fredholm modules and the segal - shale - stinespring version of canonical quantization, and taking as starting point the first - quantized fields described by connes ' axioms for noncommutative spin geometries, a hamiltonian framework for fermion quantum fields over noncommutative manifolds is introduced. we analyze the ultraviolet behaviour of second - quantized fields over noncommutative 3 - tori, and discuss what behaviour should be expected on other noncommutative spin manifolds.
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arxiv:hep-th/9804001
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we study critical phenomena in the collapse of rotating ultrarelativistic perfect fluids, in which the pressure $ p $ is related to the total energy density $ \ rho $ by $ p = \ kappa \ rho $, with $ \ kappa $ a constant. we generalize earlier results for radiation fluids with $ \ kappa = 1 / 3 $ to other values of $ \ kappa $, focussing on $ \ kappa < 1 / 9 $. for $ 1 / 9 < \ kappa \ lesssim 0. 49 $, the critical solution has only one unstable, growing mode, which is spherically symmetric. for supercritical data it controls the black hole mass, while for subcritical data it controls the maximum density. for $ \ kappa < 1 / 9 $, an additional axial $ l = 1 $ mode becomes unstable. this controls either the black hole angular momentum, or the maximum angular velocity. in theory, the additional unstable $ l = 1 $ mode changes the nature of the black hole threshold completely : at sufficiently large initial rotation rates $ \ omega $ and sufficient fine - tuning of the initial data to the black hole threshold we expect to observe nontrivial universal scaling functions ( familiar from critical phase transitions in thermodynamics ) governing the black hole mass and angular momentum, and, with further fine - tuning, eventually a finite black hole mass almost everywhere on the threshold. in practice, however, the second unstable mode grows so slowly that we do not observe this breakdown of scaling at the level of fine - tuning we can achieve, nor systematic deviations from the leading - order power - law scalings of the black hole mass. we do see systematic effects in the black - hole angular momentum, but it is not clear yet if these are due to the predicted non - trivial scaling functions, or to nonlinear effects at sufficiently large initial angular momentum ( which we do not account for in our theoretical model ).
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arxiv:1712.05741
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spin - dynamics simulations have been used to investigate the dynamic behavior of rbmnf _ 3, treating it as a classical heisenberg antiferromagnet on a simple cubic lattice. time - evolutions of spin configurations were determined numerically from coupled equations of motion for individual spins using a new algorithm which is based on suzuki - trotter decompositions of exponential operators. the dynamic structure factor was calculated from the space - and time - displaced spin - spin correlation function. the crossover from hydrodynamic to critical behavior of the dispersion curve and spin - wave half - width was studied as the temperature was increased towards the critical value. the dynamic critical exponent was estimated to be z = ( 1. 43 \ pm 0. 03 ), which is slightly lower than the dynamic scaling prediction, but in good agreement with a recent experimental value. comparisons are made of both the dispersion curve and the lineshapes obtained from our simulations with very recent experimental results for rbmnf _ 3 are presented.
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arxiv:cond-mat/9912374
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nowadays, cities are frequently exposed to heatwaves, worsening the outdoor thermal comfort and increasing cooling energy demand in summer. urban forestry is seen as one of the viable and preferable solutions to combating extreme heat events and urban heat island ( uhi ) in times of climate change. while many cities have initiated tree - planting programmes in recent years, the evolving impact of trees on street microclimate, in a time span of up to several decades, remains unclear. we investigate the cooling effects of linden trees in five groups, i. e., 10 - 20, 20 - 30, 30 - 40, 40 - 60, and 60 - 100 years old. the leaf area index ( lai ) and leaf area density ( lad ) vary nonlinearly as the trees grow, peaking at different ages. computational fluid dynamics ( cfd ) simulations solving microclimate are performed for an idealized street canyon with trees of varied age groups. turbulent airflow, heat and moisture transport, shortwave and longwave radiation, shading and transpiration are fully coupled and solved in openfoam. the meteorological data, including air temperature, wind speed, moisture, and shortwave radiation of the heatwave in zurich ( june 2019 ), are applied as boundary conditions. the results show that young trees in the age group of 10 - 20 years old provide little heat mitigation at the pedestrian level in an extreme heat event. optimal heat mitigation by trees is observed for the group of 30 - 60 years old trees. finally, the potential impact of growing trees as a heat mitigation measure on air ventilation is evaluated.
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arxiv:2301.09935
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we determine what isogeny classes of supersingular abelian surfaces over a finite field k of characteristic 2 contain jacobians. we deal with this problem in a direct way by computing explicitly the zeta function of all supersingular curves of genus 2. our procedure is constructive, so that we are able to exhibit curves with prescribed zeta function and to count the number of curves, up to k - isomorphism, leading to the same zeta function.
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arxiv:math/0408383
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courant theorem provides an upper bound for the number of nodal domains of eigenfunctions of a wide class of laplacian - type operators. in particular, it holds for generic eigenfunctions of quantum graph. the theorem stipulates that, after ordering the eigenvalues as a non decreasing sequence, the number of nodal domains $ \ nu _ n $ of the $ n $ - th eigenfunction satisfies $ n \ ge \ nu _ n $. here, we provide a new interpretation for the courant nodal deficiency $ d _ n = n - \ nu _ n $ in the case of quantum graphs. it equals the morse index - - - at a critical point - - - of an energy functional on a suitably defined space of graph partitions. thus, the nodal deficiency assumes a previously unknown and profound meaning - - - it is the number of unstable directions in the vicinity of the critical point corresponding to the $ n $ - th eigenfunction. to demonstrate this connection, the space of graph partitions and the energy functional are defined and the corresponding critical partitions are studied in detail.
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arxiv:1103.1423
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this paper considers the budget constrained fuel treatment scheduling ( bfts ) problem where, in the context of wildfire mitigation, the goal is to inhibit the potential of fire spread in a landscape by proper fuel treatment activities. given a time horizon represented by consecutive unit periods, the landscape is divided into cells and represented as a grid graph where each cell has a fuel age that increases over time and becomes old if no treatment is applied in the meantime : this induces a potential high fire risk whenever two contiguous cells are old. cells fuel ages can be reset to zero under appropriate fuel treatments but there is a limited budget for treatment in each period. the problem calls for finding a suitable selection of cells to be treated so as to minimize the presence of old contiguous cells over the whole time horizon. we prove that problem bfts is strongly np - complete on paths and thus on grid graphs and show that no polynomial time approximation algorithm exists unless p = np. we provide an enhanced integer linear programming formulation of the problem with respect to the relevant literature that shows up to be efficiently solved by an ilp solver on reasonably large size instances. finally, we consider a harder periodic variant of the problem with the aim of finding a cyclic treatment plan with cycles of length t and propose a matheuristic approach capable of efficiently tackling those instances where an ilp solver applied to the ilp formulation runs into difficulties.
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arxiv:2005.06225
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noether ' s theorem relates constants of motion to the symmetries of the system. here we investigate a manifestation of noether ' s theorem in non - hermitian systems, where the inner product is defined differently from quantum mechanics. in this framework, a generalized symmetry which we term pseudo - chirality emerges naturally as the counterpart of symmetries defined by a commutation relation in quantum mechanics. using this observation, we reveal previously unidentified constants of motion in non - hermitian systems with parity - time and chiral symmetries. we further elaborate the disparate implications of pseudo - chirality induced constant of motion : it signals the pair excitation of a generalized " particle " and the corresponding " hole " but vanishes universally when the pseudo - chiral operator is anti - symmetric. this disparity, when manifested in a non - hermitian topological lattice with the landau gauge, depends on whether the lattice size is even or odd. we further discuss previously unidentified symmetries of this non - hermitian topological system, and we reveal how its constant of motion due to pseudo - chirality can be used as an indicator of whether a pure chiral edge state is excited.
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arxiv:2101.09239
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the rockwell rprv - 870 himat ( highly maneuverable aircraft technology ) is an experimental remotely piloted aircraft that was produced for a nasa program to develop technologies for future fighter aircraft. among the technologies explored were close - coupled canards, fully digital flight control ( including propulsion ), composite materials ( graphite and fiberglass ), remote piloting, synthetic vision systems, winglets, and others. two aircraft were produced by rockwell international. their first flights took place in 1979, and testing was completed in 1983. = = design and development = = the himats were remotely piloted, as the design team decided that it would be cheaper and safer to not risk a pilot ' s life during the experiments. this also meant that no ejection seat would have to be fitted. the aircraft was flown by a pilot in a remote cockpit, and control signals up - linked from the flight controls in the remote cockpit on the ground to the aircraft, and aircraft telemetry downlinked to the remote cockpit displays. the remote cockpit could be configured with either nose camera video or with a 3d synthetic vision display called a " visual display ". the aircraft were launched from a b - 52 stratofortress at altitude. there was also a tf - 104g starfighter chase plane with a set of backup controls which could take control of the himat in the event that the remote pilot on the ground lost control. advances in digital flight control gained during the project contributed to the grumman x - 29 experimental aircraft, and composite construction are used widely on both commercial and military aircraft. the aircraft ' s initial concept included a wedge - shaped exhaust nozzle with 2d thrust vectoring. = = aircraft on display = = the two himat aircraft are now on display, one at the national air and space museum and the other at the armstrong flight research center. = = specifications = = data from boeing. comgeneral characteristics crew : none length : 22 ft 6 in ( 6. 86 m ) wingspan : 15 ft 7 in ( 4. 75 m ) height : 4 ft 4 in ( 1. 31 m ) empty weight : 3, 370 lb ( 1, 529 kg ) gross weight : 4, 030 lb ( 1, 828 kg ) powerplant : 1 Γ general electric j85 - ge - 21 turbojet performance maximum speed : 1, 218 mph ( 1, 960 km / h, 1, 058 kn ) maximum speed : mach 1. 6 = = gallery = = = = see also = = list of
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https://en.wikipedia.org/wiki/Rockwell_HiMAT
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we show that length minimizing curves in carnot - carath \ ' eodory spaces possess at any point at least one tangent curve ( i. e., a blow - up in the nilpotent approximation ) equal to a straight horizontal line. this is the first regularity result for length minimizers that holds with no assumption on either the space ( e. g., its rank, step, or analyticity ) or the curve, and it is novel even in the setting of carnot groups.
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arxiv:1609.07261
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barkhausen noise in disordered ferromagnets is typically understood to originate primarily from jerky field - driven motion of domain walls. we study the magnetization reversal process in disordered permalloy thin films using micromagnetic simulations, and find that the magnetization reversal process consists of gradual formation of immobile 360 $ ^ { \ circ } $ domain walls via a sequence of localized magnetization rotation events. the density of 360 $ ^ { \ circ } $ domain walls formed within the sample as well as the statistical properties of the barkhausen jumps are controlled by the disorder strength.
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arxiv:2209.10847
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we show that a ferromagnetic bose - einstein condensate has not only line - like vortex excitations, but in general also allows for point - like topological excitations, i. e., skyrmions. we discuss the thermodynamic stability and the dynamic properties of these skyrmions for both spin - 1 / 2 and ferromagnetic spin - 1 bose gases.
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arxiv:cond-mat/0107302
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we give a small data global well - posedness result for an incompressible oldroyd - b model with wave number dissipation in the equation of stress tensor. the result is uniform in solvent reynolds numbers, and requires only fractional wave - number dependent dissipation $ ( - \ delta ) ^ { \ beta } $, $ \ beta \ ge \ frac { 1 } { 2 } $ in the added stress.
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arxiv:2001.03703
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the covid - 19 outbreak greatly limited human activities and reduced primary emissions particularly from urban on - road vehicles, but coincided with beijing experiencing pandemic haze, raising the public concerns of the validity and effectiveness of the imposed traffic policies to improve the air pollution. here, we explored the relationship between local vehicle emissions and the winter haze in beijing before and during the covid - 19 lockdown period based on an integrated analysis framework, which combines a real - time on - road emission inventory, in - situ air quality observations and a localized chemical transport modeling system. we found that traffic emissions decreased substantially affected by the pandemic, with a higher reduction for nox ( 75. 9 %, 125. 3 mg / day ) compared to vocs ( 53. 1 %, 52. 9 mg / day ). unexpectedly, our results show that the imbalanced emission abatement of nox and vocs from vehicles led to a significant rise of the atmospheric oxidizing capacity in urban areas, but only resulting in modest increases in secondary aerosols due to the inadequate precursors. however, the enhanced oxidizing capacity in the surrounding regions greatly increased the secondary particles with relatively abundant precursors, which is mainly responsible for beijing haze during the lockdown period. our results indicate that the winter haze in beijing was insensitive to the local vehicular emissions reduction due to the complicated nonlinear response of the fine particle and air pollutant emissions. we suggest mitigation policies should focus on accelerating voc and nh3 emissions reduction and synchronously controlling regional sources to release the benefits on local traffic emission control.
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arxiv:2006.07297
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we calculate the canonical partition function $ z _ n $ for a system of $ n $ free particles obeying so - called ` quon ' statistics where $ q $ is real and satisfies $ | q | < 1 $ by using simple counting arguments. we observe that this system is afflicted by the gibbs paradox and that $ z _ n $ is independent of $ q $. we demonstrate that such a system of particles obeys the ideal gas law and that the internal energy $ u $ ( and hence the specific heat capacity $ c _ v $ ) is identical to that of a system of $ n $ free particles obeying maxwell - boltzmann statistics.
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arxiv:hep-th/9410096
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the statistical correlations between defects in the two dimensional complex ginsburg - landau model are studied in the defect - coarsening regime. in particular the defect - velocity probability distribution is determined and has the same high velocity tail found for the purely dissipative time - dependent ginsburg - landau ( tdgl ) model. the spiral arms of the defects lead to a very different behavior for the order parameter correlation function in the scaling regime compared to the results for the tdgl model.
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arxiv:cond-mat/0102330
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materials with optical activity can rotate the polarization plane of transmitted light. the most typical example is the natural optical activity, which has the symmetry property of changing sign after space inversion but being invariant to time inversion. faraday rotation exhibits the opposite : it is invariant to space inversion but changes sign after time reversal. here, we demonstrate that in a magnetoelectric material, another type of polarization rotation is possible. this effect is investigated in magnetoelectric ybal3 ( bo3 ) 4 under the viewpoint of time and space inversion symmetry arguments. we observe the sign change of the rotation sense under either time or space reversal. this investigation proves that the polarization rotation in ybal3 ( bo3 ) 4 must be classified as gyrotropic birefringence, which has been discussed within the idea of time - reversal breaking in underdoped cuprates. the diagonal terms in the magnetoelectric susceptibility are responsible for the observed signal of gyrotropic birefringence. further analysis of the experimental spectra reveals a substantial contribution of the natural optical activity to the polarization rotation. we also demonstrate that the observed activity originates from the magnetoelectric susceptibility.
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arxiv:1907.06899
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= = the connection between mathematics and material reality has led to philosophical debates since at least the time of pythagoras. the ancient philosopher plato argued that abstractions that reflect material reality have themselves a reality that exists outside space and time. as a result, the philosophical view that mathematical objects somehow exist on their own in abstraction is often referred to as platonism. independently of their possible philosophical opinions, modern mathematicians may be generally considered as platonists, since they think of and talk of their objects of study as real objects. armand borel summarized this view of mathematics reality as follows, and provided quotations of g. h. hardy, charles hermite, henri poincare and albert einstein that support his views. something becomes objective ( as opposed to " subjective " ) as soon as we are convinced that it exists in the minds of others in the same form as it does in ours and that we can think about it and discuss it together. because the language of mathematics is so precise, it is ideally suited to defining concepts for which such a consensus exists. in my opinion, that is sufficient to provide us with a feeling of an objective existence, of a reality of mathematics... nevertheless, platonism and the concurrent views on abstraction do not explain the unreasonable effectiveness of mathematics ( as platonism assumes mathematics exists independently, but does not explain why it matches reality ). = = = proposed definitions = = = there is no general consensus about the definition of mathematics or its epistemological status β that is, its place inside knowledge. a great many professional mathematicians take no interest in a definition of mathematics, or consider it undefinable. there is not even consensus on whether mathematics is an art or a science. some just say, " mathematics is what mathematicians do ". a common approach is to define mathematics by its object of study. aristotle defined mathematics as " the science of quantity " and this definition prevailed until the 18th century. however, aristotle also noted a focus on quantity alone may not distinguish mathematics from sciences like physics ; in his view, abstraction and studying quantity as a property " separable in thought " from real instances set mathematics apart. in the 19th century, when mathematicians began to address topics β such as infinite sets β which have no clear - cut relation to physical reality, a variety of new definitions were given. with the large number of new areas of mathematics that have appeared since the beginning of the 20th century, defining mathematics by its object of study has become increasingly difficult. for example, in lieu of a definition
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https://en.wikipedia.org/wiki/Mathematics
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we propose to represent a return model and risk model in a unified manner with deep learning, which is a representative model that can express a nonlinear relationship. although deep learning performs quite well, it has significant disadvantages such as a lack of transparency and limitations to the interpretability of the prediction. this is prone to practical problems in terms of accountability. thus, we construct a multifactor model by using interpretable deep learning. we implement deep learning as a return model to predict stock returns with various factors. then, we present the application of layer - wise relevance propagation ( lrp ) to decompose attributes of the predicted return as a risk model. by applying lrp to an individual stock or a portfolio basis, we can determine which factor contributes to prediction. we call this model a deep factor model. we then perform an empirical analysis on the japanese stock market and show that our deep factor model has better predictive capability than the traditional linear model or other machine learning methods. in addition, we illustrate which factor contributes to prediction.
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arxiv:1810.01278
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{ \ frac { q ^ { 2 } - 1 } { q } } k ( { \ tfrac { 1 } { q ^ { 2 } } } ) { \ biggr ) } { \ biggr \ } } \ \ [ 0. 6ex ] & = { \ frac { 4 } { 9 \ pi } } { \ biggl \ { } q ( q ^ { 2 } + 7 ) e ( { \ tfrac { 1 } { q ^ { 2 } } } ) - { \ frac { q ^ { 2 } - 1 } { q } } ( q ^ { 2 } + 3 ) k ( { \ tfrac { 1 } { q ^ { 2 } } } ) { \ biggr \ } } \ end { aligned } } } using standard integrals. hence again b ( 1 ) = 32 / 9Ο, while also lim q β β b ( q ) = q + 1 8 q. { \ displaystyle \ lim _ { q \ to \ infty } b ( q ) = q + { \ tfrac { 1 } { 8q } }. } = = see also = = unit disk, a disk with radius one annulus ( mathematics ), the region between two concentric circles ball ( mathematics ), the usual term for the 3 - dimensional analogue of a disk disk algebra, a space of functions on a disk circular segment orthocentroidal disk, containing certain centers of a triangle = = references = =
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https://en.wikipedia.org/wiki/Disk_(mathematics)
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the einstein - cartan theory of gravity can arise from a mechanism of spontaneous symmetry breaking within the context of pre - geometric gauge theories. in this work, we develop the hamiltonian analysis of such theories. by making contact with the adm formalism, we show that all the results of canonical general relativity are correctly recovered in the ir limit of the spontaneously broken phase. we then apply dirac ' s algorithm to study the algebra of constraints and determine the number of degrees of freedom in the uv limit of the unbroken phase. we also discuss possible pathways toward a uv completion of general relativity, including a pre - geometric generalisation of the wheeler - dewitt equation and an extended bf formulation of the pre - geometric theory.
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arxiv:2505.01272
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terms of the form ab, where a and b are real positive numbers or variable expressions. they often appear in mathematical olympiads exercises. examples : for any real x, e x β₯ 1 + x. { \ displaystyle e ^ { x } \ geq 1 + x. } if x > 0 and p > 0, then x p β 1 p β₯ ln ( x ) β₯ 1 β 1 x p p. { \ displaystyle { \ frac { x ^ { p } - 1 } { p } } \ geq \ ln ( x ) \ geq { \ frac { 1 - { \ frac { 1 } { x ^ { p } } } } { p } }. } in the limit of p β 0, the upper and lower bounds converge to ln ( x ). if x > 0, then x x β₯ ( 1 e ) 1 e. { \ displaystyle x ^ { x } \ geq \ left ( { \ frac { 1 } { e } } \ right ) ^ { \ frac { 1 } { e } }. } if x > 0, then x x x β₯ x. { \ displaystyle x ^ { x ^ { x } } \ geq x. } if x, y, z > 0, then ( x + y ) z + ( x + z ) y + ( y + z ) x > 2. { \ displaystyle \ left ( x + y \ right ) ^ { z } + \ left ( x + z \ right ) ^ { y } + \ left ( y + z \ right ) ^ { x } > 2. } for any real distinct numbers a and b, e b β e a b β a > e ( a + b ) / 2. { \ displaystyle { \ frac { e ^ { b } - e ^ { a } } { b - a } } > e ^ { ( a + b ) / 2 }. } if x, y > 0 and 0 < p < 1, then x p + y p > ( x + y ) p. { \ displaystyle x ^ { p } + y ^ { p } > \ left ( x + y \ right ) ^ { p }. } if x, y, z > 0, then x x y y z z β₯ ( x y z ) ( x + y + z ) / 3. { \ displaystyle x ^ { x } y ^ {
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https://en.wikipedia.org/wiki/Inequality_(mathematics)
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we report on the first analytic nnll calculation for the matrix elements of the operators o _ 1 and o _ 2 for the inlusive process b - - > x _ s l ^ + l ^ - in the kinematical region q ^ 2 > 4m _ c ^ 2, where q ^ 2 is the invariant mass squared of the lepton - pair.
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arxiv:1001.0518
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we use functions of a bicomplex variable to unify the existing constructions of harmonic morphisms from a 3 - dimensional euclidean or pseudo - euclidean space to a riemannian or lorentzian surface. this is done by using the notion of complex - harmonic morphism between complex - riemannian manifolds and showing how these are given by bicomplex - holomorphic functions when the codomain is one - bicomplex dimensional. by taking real slices, we recover well - known compactifications for the three possible real cases. on the way, we discuss some interesting conformal compactifications of complex - riemannian manifolds by interpreting them as bicomplex manifolds.
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arxiv:0910.1036
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we investigate the quantum mpemba effect ( qme ) in isolated, non - integrable quantum systems, where relaxation dynamics depend on structure of the initial states. by analyzing the distribution of initial states across symmetrical subspaces, we identify a tunable mechanism that influences the emergence of qme, showing faster relaxation from certain out - of - equilibrium states. additionally, we propose an experimentally realizable quantum circuit, which requires no complex controls on quantum simulator platforms and serves to verify our theoretical predictions. these results establish symmetry - resolved state engineering as a practical tool for manipulating non - equilibrium quantum dynamics.
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arxiv:2505.02040
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using the 9 years of continuous data now available from the burst and transient source experiment ( batse ) aboard cgro, we have measured orbital periods and produced folded lightcurves for 8 high mass x - ray binaries ( hmxb ). given the length of the datasets, our determinations are based on many more binary orbits than previous investigations. thus our source detections have high statistical significance and we are able to follow long - term trends in x - ray output. in particular we focus on two systems : a0538 - 668 and exo2030 + 375 both hmxbs exhibiting type i outbursts.
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arxiv:astro-ph/0209089
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microlensing promises to be a powerful tool for studying distant galaxies and quasars. as the data and models improve, there are systematic effects that need to be explored. quasar continuum and broad - line regions may respond differently to microlensing due to their different sizes ; to understand this effect, we study microlensing of finite sources by a mass function of stars. we find that microlensing is insensitive to the slope of the mass function but does depend on the mass range. for negative parity images, diluting the stellar population with dark matter increases the magnification dispersion for small sources and decreases it for large sources. this implies that the quasar continuum and broad - line regions may experience very different microlensing in negative - parity lensed images. we confirm earlier conclusions that the surface brightness profile and geometry of the source have little effect on microlensing. finally, we consider non - circular sources. we show that elliptical sources that are aligned with the direction of shear have larger magnification dispersions than sources with perpendicular alignment, an effect that becomes more prominent as the ellipticity increases. elongated sources can lead to more rapid variability than circular sources, which raises the prospect of using microlensing to probe source shape.
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arxiv:astro-ph/0612542
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this review deals with the inconsistency of inner dark matter density profiles in dwarf galaxies, known as the cusp - core problem. particularly, we aim to focus on gas - poor dwarf galaxies. one of the most promising solutions to this cold dark matter small scale issue is the stellar feedback but it seems to be only designed for gas - rich dwarfs. however, in the regime of classical dwarfs, this core mechanism becomes negligible. therefore, it is required to find solutions without invoking these baryonic processes as dark matter cores tend to persist even for these dwarfs, which are rather dark matter - dominated. here we have presented two categories of solutions. one consists of creating dark matter cores from cusps within cold dark matter by altering the dark matter potential via perturbers. the second category gathers solutions which depict the natural emergence of dark matter cores in alternative theories. given the wide variety of solutions, it becomes necessary to identify which mechanism dominates in the central region of galaxies by finding observational signatures left by them in order to highlight the true nature of dark matter.
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arxiv:2201.01056
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we give a complete classification of polynomial models for smooth real hypersurfaces of finite catlin multitype in $ \ mathbb c ^ 3 $, which admit nonlinear infinitesimal cr automorphisms. as a consequence, we obtain a sharp 1 - jet determination result for any smooth hypersurface with such model. the results also prove a conjecture of the first author about the origin of such nonlinear automorphisms ( aim list of problems, 2010 ). as another consequence, we describe all possible dimensions of the lie algebra of infinitesimal cr automorphisms, which leads to a new " secondary " gap phenomenon.
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arxiv:1703.07123
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resource provisioning in multi - tenant stream processing systems faces the dual challenges of keeping resource utilization high ( without over - provisioning ), and ensuring performance isolation. in our common production use cases, where streaming workloads have to meet latency targets and avoid breaching service - level agreements, existing solutions are incapable of handling the wide variability of user needs. our framework called cameo uses fine - grained stream processing ( inspired by actor computation models ), and is able to provide high resource utilization while meeting latency targets. cameo dynamically calculates and propagates priorities of events based on user latency targets and query semantics. experiments on microsoft azure show that compared to state - of - the - art, the cameo framework : i ) reduces query latency by 2. 7x in single tenant settings, ii ) reduces query latency by 4. 6x in multi - tenant scenarios, and iii ) weathers transient spikes of workload.
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arxiv:2010.03035
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we investigate the effects of yukawa couplings on the phenomenological predictions for a class of supersymmetric models which allows for the presence of complete su ( 5 ) multiplets in addition to the minimal supersymmetric standard model spectrum. we develop a two loop analytical approach to quantify the predictions for gauge unification including yukawa couplings. the effects of the heavy thresholds of the model are also included. in some cases accurate predictions can be made for the unification scale, irrespective of the initial ( unknown ) yukawa couplings, so long as perturbation theory remains valid. we also consider the limit of a large number of extra states and compute the predictions in a resummed perturbation series approach to show that the results are stable in this limit. finally we consider the possibility of making predictions for the case the gauge and yukawa couplings enter the non - perturbative domain below the unification scale and estimate the errors which affect these predictions.
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arxiv:hep-ph/9804437
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we study the dilaton stabilization in models with anomalous u ( 1 ) symmetry by adding specific string - motivated, non - perturbative corrections to the tree - level dilaton k \ " { a } hler potential. we find that the non - perturbative effects can stabilize the dilaton at a desirably large value. we also observe that the size of fayet - iliopoulos term is reduced at the stabilized point.
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arxiv:hep-ph/0311315
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this paper studies the algorithms for the minimisation of weighted automata. it starts with the definition of morphisms - which generalises and unifies the notion of bisimulation to the whole class of weighted automata - and the unicity of a minimal quotient for every automaton, obtained by partition refinement. from a general scheme for the refinement of partitions, two strategies are considered for the computation of the minimal quotient : the domain split and the predecesor class split algorithms. they correspond respectivly to the classical moore and hopcroft algorithms for the computation of the minimal quotient of deterministic boolean automata. we show that these two strategies yield algorithms with the same quadratic complexity and we study the cases when the second one can be improved in order to achieve a complexity similar to the one of hopcroft algorithm.
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arxiv:2112.09387
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transformer models have achieved state - of - the - art performance across a wide range of machine learning tasks. there is growing interest in training transformers on resource - constrained edge devices due to considerations such as privacy, domain adaptation, and on - device scientific machine learning. however, the significant computational and memory demands required for transformer training often exceed the capabilities of an edge device. leveraging low - rank tensor compression, this paper presents the first on - fpga accelerator for end - to - end transformer training. on the algorithm side, we present a bi - directional contraction flow for tensorized transformer training, significantly reducing the computational flops and intra - layer memory costs compared to existing tensor operations. on the hardware side, we store all highly compressed model parameters and gradient information on chip, creating an on - chip - memory - only framework for each stage in training. this reduces off - chip communication and minimizes latency and energy costs. additionally, we implement custom computing kernels for each training stage and employ intra - layer parallelism and pipe - lining to further enhance run - time and memory efficiency. through experiments on transformer models within $ 36. 7 $ to $ 93. 5 $ mb using fp - 32 data formats on the atis dataset, our tensorized fpga accelerator could conduct single - batch end - to - end training on the amd alevo u50 fpga, with a memory budget of less than $ 6 $ - mb bram and $ 22. 5 $ - mb uram. compared to uncompressed training on the nvidia rtx 3090 gpu, our on - fpga training achieves a memory reduction of $ 30 \ times $ to $ 51 \ times $. our fpga accelerator also achieves up to $ 3. 6 \ times $ less energy cost per epoch compared with tensor transformer training on an nvidia rtx 3090 gpu.
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arxiv:2501.06663
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cyberbullying and online harassment have serious negative psychological and emotional consequences for the victims, such as decreased life satisfaction, suicidal ideation, self - harming behaviors, depression, anxiety, and others. most of the prior works assessed people ' s emotional responses via questionnaires, while social media platforms contain data that could provide valuable insights into users ' emotions in real online discussions. therefore, this data - driven study investigates the effect of toxicity on twitter users ' emotions and other factors associated with expressing anger, anxiety, and sadness in terms of account identifiability, activity, conversation structure, and conversation topic. to achieve this goal, we identified toxic replies in the large dataset consisting of 79, 799 random twitter conversations and obtained the emotions expressed in these conversations. then, we performed propensity score matching and analyzed causal associations between toxicity and users ' emotions. in general, we found that users receiving toxic replies are more likely to express emotions of anger, sadness, and anxiety compared to users who did not receive toxic replies. finally, analysis results indicate that the conversation topic and users ' account characteristics are likely to affect their emotional responses to toxicity. our findings provide a better understanding of toxic replies ' consequences on users ' emotional states, which can potentially lead to developing personalized moderation methods that will help users emotionally cope with toxicity on social media.
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arxiv:2310.11436
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a study of possible superconducting phases of graphene has been constructed in detail. a realistic tight binding model, fit to ab initio calculations, accounts for the li - decoration of graphene with broken lattice symmetry, and includes $ s $ and $ d $ symmetry bloch character that influences the gap symmetries that can arise. the resulting seven hybridized li - c orbitals that support nine possible bond pairing amplitudes. the gap equation is solved for all possible gap symmetries. one band is weakly dispersive near the fermi energy along $ \ gamma \ rightarrow m $ where its bloch wave function has linear combination of $ d _ { x ^ 2 - y ^ 2 } $ and $ d _ { xy } $ character, and is responsible for $ d _ { x ^ { 2 } - y ^ { 2 } } $ and $ d _ { xy } $ pairing with lowest pairing energy in our model. these symmetries almost preserve properties from a two band model of pristine graphene. another part of this band, along $ k \ rightarrow \ gamma $, is nearly degenerate with upper $ s $ band that favors extended $ s $ wave pairing which is not found in two band model. upon electron doping to a critical chemical potential $ \ mu _ 1 = 0. 22 ev $ the pairing potential decreases, then increases until a second critical value $ \ mu _ 2 $ = 1. 3 ev at which a phase transition to a new phase which is not appear in two band model. this phase in the pristine graphene converts to usual extended s - wave pairing.
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arxiv:1804.03747
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effective methods of preventing falls significantly improve the quality of life of the elderly. nowadays, people focus mainly on the proper provision of the apartment with handrails and fall detection systems once they have occurred. the article presents a ~ system of active detection and classification of the risk of falls in the home space using a ~ service robot equipped with a ~ vision sensor. hazard classification allows for effective performance of tasks assigned to the robot while maintaining a ~ high level of user safety.
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arxiv:2103.09298
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in this work, we report observation of strain effect on physical properties of sr2iro4 thin films grown on srtio3 ( 001 ) and laalo3 ( 001 ) substrates. it is found that the film on laalo3 with compressive strain has a lower antiferromagnetic transition temperature ( tn ~ 210 k ) than the film on srtio3 ( tn ~ 230 k ) with tensile strain, which is probably caused by modified interlayer coupling. interestingly, magnetoresistance due to pseudospin - flip of the film on laalo3 is much larger than that of tensile - strained film on srtio3, and robust anisotropic magnetoresistance is observed in the former, but h - driven reversal behavior is seen in the latter. by performing first principles calculations, it is revealed that epitaxial strain plays an efficient role in tuning the canting angle of jeff = 1 / 2 moments and thus net moment at every iro2 layer, responsible for the difference in magnetoresistance between the films. the reversal of anisotropic magnetoresistance in the thin film on srtio3 can be ascribed to stabilization of a metastable stable with smaller bandgap as the jeff = 1 / 2 moments are aligned along the diagonal of basal plane by h. however, theoretical calculations reveal much higher magnetocrystalline anisotropy energy in the film on laalo3. this causes difficulties to drive the jeff = 1 / 2 moments to reach the diagonal and thereby the metastable state, explaining the distinct anisotropic magnetoresistance between two samples in a qualitative sense. our findings indicate that strain can be a highly efficient mean to engineer the functionalities of jeff = 1 / 2 antiferromagnet sr2iro4.
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arxiv:2309.08981
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in this paper we introduce the notion of a caristi - banach type $ \ mathcal { z } _ { r } ^ { b } $ - contraction in the framework of $ b $ - metric space endowed with a transitive relation that combine the ideas of caristi type contraction and banach contraction with a help of simulation function. we present an example to clarify the statement of the given result.
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arxiv:2002.01162
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the population dynamics that evolves in the radial symmetric geometry is investigated. the nonlinear reaction - diffusion model, which depends on population density, is employed as the governing equation for this system. the approximate analytical solution to this equation has been found. it shows that the population density evolves from initial state and propagates as the traveling wave - like for the large time scale. one can be mentioned that, if the distance is insufficient large, the curvature has ineluctable influence on density profile and front speed. in comparison, the analytical solution is in agreement with the numerical solution.
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arxiv:1305.2340
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today, the ai community is obsessed with ' state - of - the - art ' scores ( 80 % papers in neurips ) as the major performance metrics, due to which an important parameter, i. e., the environmental metric, remains unreported. computational capabilities were a limiting factor a decade ago ; however, in foreseeable future circumstances, the challenge will be to develop environment - friendly and power - efficient algorithms. the human brain, which has been optimizing itself for almost a million years, consumes the same amount of power as a typical laptop. therefore, developing nature - inspired algorithms is one solution to it. in this study, we show that currently used anns are not what we find in nature, and why, although having lower performance, spiking neural networks, which mirror the mammalian visual cortex, have attracted much interest. we further highlight the hardware gaps restricting the researchers from using spike - based computation for developing neuromorphic energy - efficient microchips on a large scale. using neuromorphic processors instead of traditional gpus might be more environment friendly and efficient. these processors will turn snns into an ideal solution for the problem. this paper presents in - depth attention highlighting the current gaps, the lack of comparative research, while proposing new research directions at the intersection of two fields - - neuroscience and deep learning. further, we define a new evaluation metric ' nature ' for reporting the carbon footprint of ai models.
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arxiv:2111.08361
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the level - $ k $ $ \ ell _ 1 $ - fourier weight of a boolean function refers to the sum of absolute values of its level - $ k $ fourier coefficients. fourier growth refers to the growth of these weights as $ k $ grows. it has been extensively studied for various computational models, and bounds on the fourier growth, even for the first few levels, have proven useful in learning theory, circuit lower bounds, pseudorandomness, and quantum - classical separations. we investigate the fourier growth of certain functions that naturally arise from communication protocols for xor functions ( partial functions evaluated on the bitwise xor of the inputs to alice and bob ). if a protocol $ \ mathcal c $ computes an xor function, then $ \ mathcal c ( x, y ) $ is a function of the parity $ x \ oplus y $. this motivates us to analyze the xor - fiber of $ \ mathcal c $, defined as $ h ( z ) : = \ mathbb e _ { x, y } [ \ mathcal c ( x, y ) | x \ oplus y = z ] $. we present improved fourier growth bounds for the xor - fibers of protocols that communicate $ d $ bits. for the first level, we show a tight $ o ( \ sqrt d ) $ bound and obtain a new coin theorem, as well as an alternative proof for the tight randomized communication lower bound for gap - hamming. for the second level, we show an $ d ^ { 3 / 2 } \ cdot \ mathrm { polylog } ( n ) $ bound, which improves the previous $ o ( d ^ 2 ) $ bound by girish, raz, and tal ( itcs 2021 ) and implies a polynomial improvement on the randomized communication lower bound for the xor - lift of forrelation, extending its quantum - classical gap. our analysis is based on a new way of adaptively partitioning a relatively large set in gaussian space to control its moments in all directions. we achieve this via martingale arguments and allowing protocols to transmit real values. we also show a connection between fourier growth and lifting theorems with constant - sized gadgets as a potential approach to prove optimal bounds for the second level and beyond.
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arxiv:2307.13926
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we introduce an intuitive and semi - analytical polaron master equation approach to model pulse - driven population inversion and emitted single photons from a quantum dot exciton. the master equation theory allows one to identify important phonon - induced scattering rates analytically, and fully includes the role of the time - dependent pump field. as an application of the theory, we first study a quantum dot driven by a time - varying laser pulse on and off resonance, showing the population inversion caused by acoustic phonon emission in direct agreement with recent experiment of quilter { \ em et al. }, phys rev lett { \ bf 114 }, 137401 ( 2015 ). we then model quantum dots in weakly coupled cavities and show the difference in population response between exciton - driven and cavity - driven systems. finally, we assess the nonresonant phonon - assisted loading scheme with a quantum dot resonantly coupled to a cavity as a deterministic single photon source, and compare and contrast the important figures of merit with direct rabi oscillation of the population using a resonant $ \ pi $ pulse, where the latter is shown to be much more efficient.
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arxiv:1512.07865
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we describe various errors in the mathematical literature, and consider how some of them might have been avoided, or at least detected at an earlier stage, using tools such as maple or sage. our examples are drawn from three broad categories of errors. first, we consider some significant errors made by highly - regarded mathematicians. in some cases these errors were not detected until many years after their publication. second, we consider in some detail an error that was recently detected by the author. this error in a refereed journal led to further errors by at least one author who relied on the ( incorrect ) result. finally, we mention some instructive errors that have been detected in the author ' s own published papers.
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arxiv:2106.07269
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a single rf bunch in the kek proton synchrotron was accelerated with an induction acceleration method from the injection energy of 500 mev to 5 gev.
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arxiv:physics/0412006
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throughput and latency critical applications could often benefit of performing computations close to the client. to enable this, distributed computing paradigms such as edge computing have recently emerged. however, with the advent of programmable data planes, computations cannot only be performed by servers but they can be offloaded to network switches. languages like p4 enable to flexibly reprogram the entire packet processing pipeline. though these devices promise high throughput and ultra - low response times, implementing application - layer tasks in the data plane programming language p4 is still challenging for an application developer who is not familiar with networking domain. in this paper, we first identify and examine obstacles and pain points one can experience when offloading server - based computations to the network. then we present p4rrot, a code generator ( in form of a library ) which allows to overcome these limitations by providing a user - friendly api to describe computations to be offloaded. after discussing the design choices behind p4rrot, we introduce our proof - of - concept implementation for two p4 targets : netronome smartnic and bmv2.
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arxiv:2204.02739
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in recent years, a deep learning framework has been widely used for object pose estimation. while quaternion is a common choice for rotation representation of 6d pose, it cannot represent an uncertainty of the observation. in order to handle the uncertainty, bingham distribution is one promising solution because this has suitable features, such as a smooth representation over so ( 3 ), in addition to the ambiguity representation. however, it requires the complex computation of the normalizing constants. this is the bottleneck of loss computation in training neural networks based on bingham representation. as such, we propose a fast - computable and easy - to - implement loss function for bingham distribution. we also show not only to examine the parametrization of bingham distribution but also an application based on our loss function.
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arxiv:2203.04456
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systems that can efficiently search collections of sign language videos have been highlighted as a useful application of sign language technology. however, the problem of searching videos beyond individual keywords has received limited attention in the literature. to address this gap, in this work we introduce the task of sign language retrieval with free - form textual queries : given a written query ( e. g., a sentence ) and a large collection of sign language videos, the objective is to find the signing video in the collection that best matches the written query. we propose to tackle this task by learning cross - modal embeddings on the recently introduced large - scale how2sign dataset of american sign language ( asl ). we identify that a key bottleneck in the performance of the system is the quality of the sign video embedding which suffers from a scarcity of labeled training data. we, therefore, propose spot - align, a framework for interleaving iterative rounds of sign spotting and feature alignment to expand the scope and scale of available training data. we validate the effectiveness of spot - align for learning a robust sign video embedding through improvements in both sign recognition and the proposed video retrieval task.
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arxiv:2201.02495
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tio2 is a wide band - gap semiconductor that has been intensively investigated for photocatalysis and water - spiting. however, weak light absorption in the visible region of the spectrum poses stringent limitation to its practical application. doping of tio2 with n or transition - metal impurities has been explored to shift the onset of optical absorption to the visible region, yet with limited success. based on hybrid density functional calculations, we propose adding bi to tio2, in the form of dilute ti _ ( 1 - x ) bi _ ( x ) o2 alloys, to efficiently shift the optical absorption to the visible region. compared to n, bi introduces an intermediate valence band that is significantly higher in the band gap, and leaves the conduction band almost unchanged, leading to a remarkable redshift in the absorption coefficient to cover almost all the visible - light spectrum. comparing formation enthalpies, our results show that adding bi costs significantly less energy than n in oxidizing conditions, and that ti _ ( 1 - x ) bi _ ( x ) o2 might make a much more efficient photocatalyst than tio _ ( 2 - y ) n _ ( y ) for water splitting.
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arxiv:2302.02461
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