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we present star ' s measurements of azimuthal correlations between non - photonic electrons and charged hadrons in p + p, cu + cu and au + au collisions at 200 gev. in p + p collisions, from the non - photonic e - h correlation we have extracted the relative b meson semi - leptonic decay contributions to non - photonic electrons up to electron $ p _ t \ sim 9 $ gev / $ c $. in central cu + cu and au + au collisions where a dense medium is created, we find that the e - h correlation on the away side of the trigger non - photonic electron has been modified in comparison with the expectation from pythia simulations.
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arxiv:0804.4448
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recently the surprising discovery of the bootstrap your own latent ( byol ) method by grill et al. shows the negative term in contrastive loss can be removed if we add the so - called prediction head to the network. this initiated the research of non - contrastive self - supervised learning. it is mysterious why even when there exist trivial collapsed global optimal solutions, neural networks trained by ( stochastic ) gradient descent can still learn competitive representations. this phenomenon is a typical example of implicit bias in deep learning and remains little understood. in this work, we present our empirical and theoretical discoveries on non - contrastive self - supervised learning. empirically, we find that when the prediction head is initialized as an identity matrix with only its off - diagonal entries being trainable, the network can learn competitive representations even though the trivial optima still exist in the training objective. theoretically, we present a framework to understand the behavior of the trainable, but identity - initialized prediction head. under a simple setting, we characterized the substitution effect and acceleration effect of the prediction head. the substitution effect happens when learning the stronger features in some neurons can substitute for learning these features in other neurons through updating the prediction head. and the acceleration effect happens when the substituted features can accelerate the learning of other weaker features to prevent them from being ignored. these two effects enable the neural networks to learn all the features rather than focus only on learning the stronger features, which is likely the cause of the dimensional collapse phenomenon. to the best of our knowledge, this is also the first end - to - end optimization guarantee for non - contrastive methods using nonlinear neural networks with a trainable prediction head and normalization.
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arxiv:2205.06226
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this paper considers the distributed event - triggered consensus problem for general linear multi - agent networks. both the leaderless and leader - follower consensus problems are considered. based on the local sampled state or local output information, distributed adaptive event - triggered protocols are designed, which can ensure that consensus of the agents is achieved and the zeno behavior is excluded by showing that the interval between any two triggering events is lower bounded by a strictly positive value. compared to the previous related works, our main contribution is that the proposed adaptive event - based protocols are fully distributed and scalable, which do not rely on any global information of the network graph and are independent of the network ' s scale. in these event - based protocols, continuous communications are not required for either control laws updating or triggering functions monitoring.
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arxiv:1807.05326
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results are presented on the production of jets of particles in association with a z / gamma * boson, in proton - proton collisions at sqrt ( s ) = 7 tev with the atlas detector. the analysis includes the full 2010 data set, collected with a low rate of multiple proton - proton collisions in the accelerator, corresponding to an integrated luminosity of 36 pb ^ - 1. inclusive jet cross sections in z / gamma * events, with z / gamma * decaying into electron or muon pairs, are measured for jets with transverse momentum pt > 30 gev and jet rapidity | y | < 4. 4. the measurements are compared to next - to - leading - order perturbative qcd calculations, and to predictions from different monte carlo generators implementing leading - order matrix elements supplemented by parton showers.
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arxiv:1111.2690
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we present radio observations at frequencies ranging from 240 to 8460 mhz of the radio galaxy 4c29. 30 ( j0840 + 2949 ) using the giant metrewave radio telescope ( gmrt ), the very large array ( vla ) and the effelsberg telescope. we report the existence of weak extended emission with an angular size of $ \ sim $ 520 arcsec ( 639 kpc ) within which a compact edge - brightened double - lobed source with a size of 29 arcsec ( 36 kpc ) is embedded. we determine the spectrum of the inner double from 240 to 8460 mhz and show that it has a single power - law spectrum with a spectral index of $ \ sim $ 0. 8. its spectral age is estimated to be $ \ lapp $ 33 myr. the extended diffuse emission has a steep spectrum with a spectral index of $ \ sim $ 1. 3 and a break frequency $ \ lapp $ 240 mhz. the spectral age is $ \ gapp $ 200 myr, suggesting that the extended diffuse emission is due to an earlier cycle of activity. we reanalyse archival x - ray data from chandra and suggest that the x - ray emission from the hotspots consists of a mixture of nonthermal and thermal components, the latter being possibly due to gas which is shock heated by the jets from the host galaxy.
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arxiv:astro-ph/0703723
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gamma ray bursts have been divided into two classes, long - soft gamma ray burst and short - hard gamma ray burst according to the bimodal distribution in duration time. due to the harder spectrum and the lack of afterglows of short - hard bursts in optical and radio observations, different progenitors for short - hard bursts and long - soft bursts have been suggested. based on the x - ray afterglow observation and the cumulative red - shift distribution of short - hard bursts, nakar et al. ( 2006 ) found that the progenitors of short - hard bursts are consistent with old populations, such as mergers of binary neutron stars. recently, the existence of two subclasses in long - soft bursts has been suggested after considering multiple characteristics of gamma - ray bursts, including fluences and the duration time. in this work, we extended the analysis of cumulative red - shift distribution to two possible subclasses in l - grbs. we found that two possible subclass grbs show different red - shift distributions, especially for red - shifts z > 1. our results indicate that the accumulative red - shift distribution can be used as a tool to constrain the progenitor characteristics of possible subclasses in l - grbs.
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arxiv:0710.1475
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mobile robots frequently navigate on roadmaps, i. e., graphs where edges represent safe motions, in applications such as healthcare, hospitality, and warehouse automation. often the environment is quasi - static, i. e., it is sufficient to construct a roadmap once and then use it for any future planning queries. roadmaps are typically used with graph search algorithm to find feasible paths for the robots. therefore, the roadmap should be well - connected, and graph searches should produce near - optimal solutions with short solution paths while simultaneously be computationally efficient to execute queries quickly. we propose a new method to construct roadmaps based on the gray - scott reaction diffusion system and delaunay triangulation. our approach, gsrm, produces roadmaps with evenly distributed vertices and edges that are well - connected even in environments with challenging narrow passages. empirically, we compare to classical roadmaps generated by 8 - connected grids, probabilistic roadmaps ( prm, spars2 ), and optimized roadmap graphs ( orm ). our results show that gsrm consistently produces superior roadmaps that are well - connected, have high query efficiency, and result in short solution paths.
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arxiv:2410.11024
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in this work, we give the general solution sequential linear conformable fractional differential equations in the case of constant coefficients for { \ alpha } ( \ in ) ( 0, 1 ]. in homogeneous case, we use a fractional exponential function which generalizes the corresponding ordinary function. in non - homogeneous case, we present to fractional the method of variation of parameters for a particular solution of sequential linear conformable fractional differential equations.
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arxiv:1602.01452
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it is quite easy to control spin polarization and spin direction of a system via magnetic fields. however, there is no such a direct and efficient way to manipulate valley pseudospin degree of freedom. here, we demonstrate experimentally that it is possible to realize valley polarization and valley inversion in graphene by using both strain - induced pseudomagnetic fields and real magnetic fields. the pseudomagnetic fields, which are quite different from real magnetic fields, pointing in opposite directions at the two distinct valleys of graphene. therefore, coexistence of the pseudomagnetic fields and the real magnetic fields leads to imbalanced effective magnetic fields at two distinct valleys of graphene. this allows us to control the valley in graphene as convenient as the electron spin. in this work, we report consistent observation of valley polarization and inversion in strained graphene via pseudo - landau levels, splitting of real landau levels and valley splitting of confined states using scanning tunneling spectroscopy. our results highlight a pathway to valleytronics in strained graphene - based platforms.
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arxiv:1812.04344
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we answer the last question left open in [ z. ~ ko \ v { c } an, \ emph { chaos on one - dimensional compact metric spaces }, internat. j. bifur. chaos appl. sci. engrg. \ textbf { 22 }, article id : 1250259 ( 2012 ) ] which asks whether there is a relation between an infinite ly - scrambled set and $ \ omega $ - chaos for dendrite maps. we construct a continuous self - map of a dendrite without an infinite ly - scrambled set but containing an uncountable $ \ omega $ - scrambled set.
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arxiv:1810.02944
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we report the first uniform and systematic study of dust and molecular gas in nearby molecular clouds. we use surveys of dust extinction and emission to determine the opacity and map the distribution of the dust within a dozen local clouds in order to derive a uniform set of basic cloud properties. we find : 1 ) the average dust opacity $ \ langle \ kappa _ { d, 353 } \ rangle = 0. 8 \ { \ rm cm ^ { 2 } \, g ^ { - 1 } } $ with variations of a factor of $ \ sim $ 2 between clouds, 2 ) cloud pdfs are exquisitely described by steeply falling power - laws with a narrow range of slope, and 3 ) a tight $ m _ { \ rm gmc } \ sim r _ { \ rm gmc } ^ 2 $ scaling relation for the cloud sample, indicative of a cloud population with an exactingly constant average surface density above a common fixed boundary. we compare these results to uniformly analyzed co surveys. we measure the co mass conversion factors and assess the efficacy of co for tracing the physical properties of molecular clouds. we find $ \ langle \ alpha _ { \ rm co } \ rangle = 4. 31 \ pm 0. 67 $ m $ _ \ odot $ ( k km s $ ^ { - 1 } $ pc $ ^ 2 $ ) $ ^ { - 1 } $ ( corresponding to $ x _ { \ rm co } $ = 1. 97 $ \ times $ 10 $ ^ { 20 } $ cm $ ^ { - 2 } $ ( k km s $ ^ { - 1 } $ ) $ ^ { - 1 } $ ). we demonstrate that co observations are a poor tracer of column density and structure on sub - cloud spatial scales. on cloud scales, co observations can provide measurements consistent with those of the dust, provided data are analyzed in a similar, self - consistent fashion. measurements of average gmc surface density are sensitive to choice of cloud boundary. care must be exercised to adopt common fixed boundaries when comparing surface densities for cloud populations within and between galaxies.
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arxiv:2203.07480
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in this paper we propose a new bayesian estimation method to solve linear inverse problems in signal and image restoration and reconstruction problems which has the property to be scale invariant. in general, bayesian estimators are { \ em nonlinear } functions of the observed data. the only exception is the gaussian case. when dealing with linear inverse problems the linearity is sometimes a too strong property, while { \ em scale invariance } often remains a desirable property. as everybody knows one of the main difficulties with using the bayesian approach in real applications is the assignment of the direct ( prior ) probability laws before applying the bayes ' rule. we discuss here how to choose prior laws to obtain scale invariant bayesian estimators. in this paper we discuss and propose a familly of generalized exponential probability distributions functions for the direct probabilities ( the prior $ p ( \ xb ) $ and the likelihood $ p ( \ yb | \ xb ) $ ), for which the posterior $ p ( \ xb | \ yb ) $, and, consequently, the main posterior estimators are scale invariant. among many properties, generalized exponential can be considered as the maximum entropy probability distributions subject to the knowledge of a finite set of expectation values of some knwon functions.
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arxiv:physics/0111125
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we study the statistics of the number of records r _ { n, n } for n identical and independent symmetric discrete - time random walks of n steps in one dimension, all starting at the origin at step 0. at each time step, each walker jumps by a random length drawn independently from a symmetric and continuous distribution. we consider two cases : ( i ) when the variance \ sigma ^ 2 of the jump distribution is finite and ( ii ) when \ sigma ^ 2 is divergent as in the case of l \ ' evy flights with index 0 < \ mu < 2. in both cases we find that the mean record number < r _ { n, n } > grows universally as \ sim \ alpha _ n \ sqrt { n } for large n, but with a very different behavior of the amplitude \ alpha _ n for n > 1 in the two cases. we find that for large n, \ alpha _ n \ approx 2 \ sqrt { \ log n } independently of \ sigma ^ 2 in case i. in contrast, in case ii, the amplitude approaches to an n - independent constant for large n, \ alpha _ n \ approx 4 / \ sqrt { \ pi }, independently of 0 < \ mu < 2. for finite \ sigma ^ 2 we argue, and this is confirmed by our numerical simulations, that the full distribution of ( r _ { n, n } / \ sqrt { n } - 2 \ sqrt { \ log n } ) \ sqrt { \ log n } converges to a gumbel law as n \ to \ infty and n \ to \ infty. in case ii, our numerical simulations indicate that the distribution of r _ { n, n } / \ sqrt { n } converges, for n \ to \ infty and n \ to \ infty, to a universal nontrivial distribution, independently of \ mu. we discuss the applications of our results to the study of the record statistics of 366 daily stock prices from the standard & poors 500 index.
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arxiv:1204.5039
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we have investigated the role of molecular anion chemistry in pseudo - time dependent chemical models of dark clouds. with oxygen - rich elemental abundances, the addition of anions results in a slight improvement in the overall agreement between model results and observations of molecular abundances in tmc - 1 ( cp ). more importantly, with the inclusion of anions, we see an enhanced production efficiency of unsaturated carbon - chain neutral molecules, especially in the longer members of the families cnh, cnh2, and hcnn. the use of carbon - rich elemental abundances in models of tmc - 1 ( cp ) with anion chemistry worsens the agreement with observations obtained in the absence of anions.
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arxiv:0905.0800
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the uncertainty relation and the probability interpretation of quantum mechanics are intrinsically connected, as is evidenced by the evaluation of standard deviations. it is thus natural to ask if one can associate a very small uncertainty product of suitably sampled events with a very small probability. we have shown elsewhere that some examples of the evasion of the uncertainty relation noted in the past are in fact understood in this way. we here numerically illustrate that a very small uncertainty product is realized if one performs a suitable sampling of measured data which occur with a very small probability. it is also shown that our analysis is consistent with the landau - pollak type uncertainty relation. it is suggested that the present analysis may help reconcile the contradicting views about the " standard quantum limit " in the detection of gravitational waves.
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arxiv:1012.1752
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it was noticed recently that, given a metric space $ ( x, d _ x ) $, the equivalence classes of metrics on the disjoint union of the two copies of $ x $ coinciding with $ d _ x $ on each copy form an inverse semigroup $ m ( x ) $ with respect to concatenation of metrics. now put this inverse semigroup construction in a more general context, namely, we define, for a c * - algebra $ a $, an inverse semigroup $ s ( a ) $ of hilbert c * - $ a $ - $ a $ - bimodules. when $ a $ is the uniform roe algebra $ c ^ * _ u ( x ) $ of a metric space $ x $, we construct a map $ m ( x ) \ to s ( c ^ * _ u ( x ) ) $ and show that this map is injective, but not surjective in general. this allows to define an analog of the inverse semigroup $ m ( x ) $ that does not depend on the choice of a metric on $ x $ within its coarse equivalence class.
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arxiv:2111.13753
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this is a personal history of the hastings - michalakis proof of quantum hall conductance quantization.
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arxiv:2009.01645
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we consider mechanisms of directed transport in a ratchet model comprising, besides the external freedom where transport occurs, a chemical freedom that replaces the familiar external driving by an autonomous dynamics providing energy input, and an internal freedom representing a functional mode of a motor molecule. the dependence of the current on various parameters is studied in numerical simulations of our model. in particular, we point out the role of the internal freedom as a buffer between energy input and output of mechanical work that allows a temporary storage of injected energy and can contribute to the efficiency of current generation.
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arxiv:1002.4012
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a growing group of low - mass x - ray binaries are found to be accreting at very - faint x - ray luminosities of < 1e36 erg / s ( 2 - 10 kev ). once such system is the new x - ray transient igr j17494 - 3030. we present swift and xmm - newton observations obtained during its 2012 discovery outburst. the swift observations trace the peak of the outburst, which reached a luminosity of ~ 7 e35 ( d / 8 kpc ) ^ 2 erg / s ( 2 - 10 kev ). the xmm - newton data were obtained when the outburst had decayed to an intensity of ~ 8 e34 ( d / 8 kpc ) ^ 2 erg / s. the spectrum can be described by a power - law with an index of ~ 1. 7 and requires an additional soft component with a black - body temperature of ~ 0. 37 kev ( contributing ~ 20 % to the total unabsorbed flux in the 0. 5 - 10 kev band ). given the similarities with high - quality spectra of very - faint neutron star low - mass x - ray binaries, we suggest that the compact primary in igr j17494 - 3030 is a neutron star. interestingly, the source intensity decreased rapidly during the ~ 12 hr xmm - newton observation, which was accompanied by a decrease in inferred temperature. we interpret the soft spectral component as arising from the neutron star surface due to low - level accretion, and propose that the observed decline in intensity was the result of a decrease in the mass - accretion rate onto the neutron star.
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arxiv:1307.6009
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in an attempt to regularize a previously known exactly solvable model [ yang and zhang, eur. j. phys. \ textbf { 40 }, 035401 ( 2019 ) ], we find yet another exactly solvable toy model. the interesting point is that while the hamiltonian of the model is parameterized by a function $ f ( x ) $ defined on $ [ 0, \ infty ) $, its spectrum depends only on the end values of $ f $, i. e., $ f ( 0 ) $ and $ f ( \ infty ) $. this model can serve as a good exercise in quantum mechanics at the undergraduate level.
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arxiv:2003.10835
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despite significant recent progress across multiple subtasks of audio source separation, few music source separation systems support separation beyond the four - stem vocals, drums, bass, and other ( vdbo ) setup. of the very few current systems that support source separation beyond this setup, most continue to rely on an inflexible decoder setup that can only support a fixed pre - defined set of stems. increasing stem support in these inflexible systems correspondingly requires increasing computational complexity, rendering extensions of these systems computationally infeasible for long - tail instruments. in this work, we propose banquet, a system that allows source separation of multiple stems using just one decoder. a bandsplit source separation model is extended to work in a query - based setup in tandem with a music instrument recognition passt model. on the moisesdb dataset, banquet, at only 24. 9 m trainable parameters, approached the performance level of the significantly more complex 6 - stem hybrid transformer demucs on vdbo stems and outperformed it on guitar and piano. the query - based setup allows for the separation of narrow instrument classes such as clean acoustic guitars, and can be successfully applied to the extraction of less common stems such as reeds and organs. implementation is available at https : / / github. com / kwatcharasupat / query - bandit.
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arxiv:2406.18747
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we present the results of a joint observational campaign between the green bank radio telescope and the veritas gamma - ray telescope, which searched for a correlation between the emission of very - high - energy ( vhe ) gamma rays ( $ e _ { \ gamma } > $ 150 gev ) and giant radio pulses ( grps ) from the crab pulsar at 8. 9 ghz. a total of 15366 grps were recorded during 11. 6 hours of simultaneous observations, which were made across four nights in december 2008 and in november and december 2009. we searched for an enhancement of the pulsed gamma - ray emission within time windows placed around the arrival time of the grp events. in total, 8 different time windows with durations ranging from 0. 033 ms to 72 s were positioned at three different locations relative to the grp to search for enhanced gamma - ray emission which lagged, led, or was concurrent with, the grp event. further, we performed separate searches on main pulse grps and interpulse grps and on the most energetic grps in our data sample. no significant enhancement of pulsed vhe emission was found in any of the preformed searches. we set upper limits of 5 - 10 times the average vhe flux of the crab pulsar on the flux simultaneous with interpulse grps on single - rotation - period time scales. on $ \ sim $ 8 - second time scales around interpulse grps, we set an upper limit of 2 - 3 times the average vhe flux. within the framework of recent models for pulsed vhe emission from the crab pulsar, the expected vhe - grp emission correlations are below the derived limits.
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arxiv:1210.4786
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the multi - stage phenomenon in the training loss curves of neural networks has been widely observed, reflecting the non - linearity and complexity inherent in the training process. in this work, we investigate the training dynamics of neural networks ( nns ), with particular emphasis on the small initialization regime, identifying three distinct stages observed in the loss curve during training : the initial plateau stage, the initial descent stage, and the secondary plateau stage. through rigorous analysis, we reveal the underlying challenges contributing to slow training during the plateau stages. while the proof and estimate for the emergence of the initial plateau were established in our previous work, the behaviors of the initial descent and secondary plateau stages had not been explored before. here, we provide a more detailed proof for the initial plateau, followed by a comprehensive analysis of the initial descent stage dynamics. furthermore, we examine the factors facilitating the network ' s ability to overcome the prolonged secondary plateau, supported by both experimental evidence and heuristic reasoning. finally, to clarify the link between global training trends and local parameter adjustments, we use the wasserstein distance to track the fine - scale evolution of weight amplitude distribution.
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arxiv:2410.20119
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numerical relativity is an essential tool in studying the coalescence of binary black holes ( bbhs ). it is still computationally prohibitive to cover the bbh parameter space exhaustively, making phenomenological fitting formulas for bbh waveforms and final - state properties important for practical applications. we describe a general hierarchical bottom - up fitting methodology to design and calibrate fits to numerical relativity simulations for the three - dimensional parameter space of quasicircular nonprecessing merging bbhs, spanned by mass ratio and by the individual spin components orthogonal to the orbital plane. particular attention is paid to incorporating the extreme - mass - ratio limit and to the subdominant unequal - spin effects. as an illustration of the method, we provide two applications, to the final spin and final mass ( or equivalently : radiated energy ) of the remnant black hole. fitting to 427 numerical relativity simulations, we obtain results broadly consistent with previously published fits, but improving in overall accuracy and particularly in the approach to extremal limits and for unequal - spin configurations. we also discuss the importance of data quality studies when combining simulations from diverse sources, how detailed error budgets will be necessary for further improvements of these already highly accurate fits, and how this first detailed study of unequal - spin effects helps in choosing the most informative parameters for future numerical relativity runs.
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arxiv:1611.00332
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the problem of constructing an optimal rooted phylogenetic network from a set of rooted triplets is an np - hard problem. in this paper, we present a heuristic algorithm called tripnet which tries to construct an optimal rooted phylogenetic network from an arbitrary set of triplets. we prove some theorems to justify the performance of the algorithm.
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arxiv:1201.3722
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the genius project is a proposal for a new dark matter detector, with an increased sensitivity of three orders of magnitude relative to existing direct dark matter detection experiments. we performed a technical study and calculated the main background sources for the relevant energy region in a detailed detector geometry. the achieved overall background level and detector performance confirm the outstanding potential of genius as a powerful tool for the direct search of wimps in our galaxy.
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arxiv:hep-ex/9811040
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we report the first detection of asymmetry in a supernova ( sn ) photosphere based on sn light echo ( le ) spectra of cas a from the different perspectives of dust concentrations on its le ellipsoid. new les are reported based on difference images, and optical spectra of these les are analyzed and compared. after properly accounting for the effects of finite dust - filament extent and inclination, we find one field where the he i and h alpha features are blueshifted by an additional ~ 4000 km / s relative to other spectra and to the spectra of the type iib sn 1993j. that same direction does not show any shift relative to other cas a le spectra in the ca ii near - infrared triplet feature. we compare the perspectives of the cas a le dust concentrations with recent three - dimensional modeling of the sn remnant ( snr ) and note that the location having the blueshifted he i and h alpha features is roughly in the direction of an fe - rich outflow and in the opposite direction of the motion of the compact object at the center of the snr. we conclude that cas a was an intrinsically asymmetric sn. future le spectroscopy of this object, and of other historical sne, will provide additional insight into the connection of explosion mechanism to sn to snr, as well as give crucial observational evidence regarding how stars explode.
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arxiv:1003.5660
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we consider a one - dimensional, weakly asymmetric, boundary driven exclusion process on the interval $ [ 0, n ] \ cap z $ in the super - diffusive time scale $ n ^ 2 \ epsilon ^ { - 1 } _ n $, where $ 1 \ ll \ epsilon ^ { - 1 } _ n \ ll n ^ { 1 / 4 } $. we assume that the external field and the chemical potentials, which fix the density at the boundaries, evolve smoothly in the macroscopic time scale. we derive an equation which describes the evolution of the density up to the order $ \ epsilon _ n $.
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arxiv:1509.05801
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the notion of adequate subgroups was introduced by jack thorne. it is a weakening of the notion of big subgroup used by wiles and taylor in proving automorphy lifting theorems for certain galois representations. using this idea, thorne was able to prove some new lifting theorems. in an appendix to thorne ' s article, it was shown in that certain groups were adequate. one of the key aspects was the question of whether the span of the semsimple elements in the group is the full endomorphism ring of an absolutely irreducible module. we show that this is the case in prime characteristic p for p - solvable groups as long the dimension is not divisible by p. we also observe that the condition holds for certain infinite groups. finally, we present the first examples showing that this condition need not hold and give a negative answer to a question of richard taylor.
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arxiv:1112.4561
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recently, there has been much interest in simulating quantum field theory effects of matter and gauge fields. in a recent work [ phys. rev. lett. 107, 275301 ( 2011 ) ] a method for simulating compact quantum electrodynamics ( cqed ) using bose - einstein condensates has been suggested. we suggest an alternative approach, which relies on single atoms in an optical lattice, carrying 2l + 1 internal levels, which converges rapidly to cqed as l increases. that enables the simulation of cqed in 2 + 1 dimensions in both the weak and the strong coupling regimes, hence allowing to probe confinement as well as other nonperturbative effects of the theory. we provide an explicit construction for the case l = 1 which is sufficient for simulating the effect of confinement between two external static charges.
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arxiv:1204.6574
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recent advances in single particle tracking and supercomputing techniques demonstrate the emergence of normal or anomalous, viscoelastic diffusion in conjunction with non - gaussian distributions in soft, biological, and active matter systems. we here formulate a stochastic model based on a generalised langevin equation in which non - gaussian shapes of the probability density function and normal or anomalous diffusion have a common origin, namely a random parametrisation of the stochastic force. we perform a detailed analytical analysis demonstrating how various types of parameter distributions for the memory kernel result in the exponential, power law, or power - log law tails of the memory functions. the studied system is also shown to exhibit a further unusual property : the velocity has a gaussian one point probability density but non - gaussian joint distributions. this behaviour is reflected in relaxation from gaussian to non - gaussian distribution observed for the position variable. we show that our theoretical results are in excellent agreement with monte carlo simulations.
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arxiv:1710.02222
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we consider a directed acyclic network with three sources and three terminals such that each source independently generates one symbol from a given field $ f $ and each terminal wants to receive the sum ( over $ f $ ) of the source symbols. each link in the network is considered to be error - free and delay - free and can carry one symbol from the field in each use. we call such a network a 3 - source 3 - terminal { \ it $ ( 3s / 3t ) $ sum - network }. in this paper, we give a necessary and sufficient condition for a $ 3s / 3t $ sum - network to allow all the terminals to receive the sum of the source symbols over \ textit { any } field. some lemmas provide interesting simpler sufficient conditions for the same. we show that linear codes are sufficient for this problem for $ 3s / 3t $ though they are known to be insufficient for arbitrary number of sources and terminals. we further show that in most cases, such networks are solvable by simple xor coding. we also prove a recent conjecture that if fractional coding is allowed, then the coding capacity of a $ 3s / 3t $ sum - network is either $ 0, 2 / 3 $ or $ \ geq 1 $.
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arxiv:1001.4137
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in this paper we give an explanation of a number of observations relating to degree growth of birational mappings of the plane and their deautonomisation by singularity confinement. these observations are of a link between two a priori unrelated notions : firstly the dynamical degree of the mapping and secondly the evolution of parameters required for its singularity structure to remain unchanged under a sufficiently general deautonomisation. we explain this correspondence for a large class of birational mappings of the plane via the spaces of initial conditions for their deautonomised versions. we show that even for non - integrable mappings in this class, the surfaces forming these spaces have effective anticanonical divisors and one can define a period map parametrising them, similar to that in the theory of rational surfaces associated with discrete painlev \ ' e equations. this provides a bridge between the evolution of coefficients in the deautonomised mapping and the induced dynamics on the picard lattice which encode the dynamical degree.
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arxiv:2306.01372
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we present some open problems and obtain some partial results for spectral optimization problems involving measure, torsional rigidity and first dirichlet eigenvalue.
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arxiv:1403.0114
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code - switching, a common phenomenon in written text and conversation, has been studied over decades by the natural language processing ( nlp ) research community. initially, code - switching is intensively explored by leveraging linguistic theories and, currently, more machine - learning oriented approaches to develop models. we introduce a comprehensive systematic survey on code - switching research in natural language processing to understand the progress of the past decades and conceptualize the challenges and tasks on the code - switching topic. finally, we summarize the trends and findings and conclude with a discussion for future direction and open questions for further investigation.
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arxiv:2212.09660
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a complete set of n + 1 mutually unbiased bases ( mubs ) exists in hilbert spaces of dimension n = p ^ k, where p is a prime number. they mesh naturally with finite affine planes of order n, that exist when n = p ^ k. the existence of mubs for other values of n is an open question, and the same is true for finite affine planes. i explore the question whether the existence of complete sets of mubs is directly related to the existence of finite affine planes. both questions can be shown to be geometrical questions about a convex polytope, but not in any obvious way the same question.
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arxiv:quant-ph/0406174
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in their article ' the inconsistency of the h - index ' ludo waltman and nees jan van neck give three examples to demonstrate the inconsistency of the h - index. as will be explained, a little extension of their examples just illustrate the opposite, a stable feature of the h - index. for starting authors it, the h - index that is, focusses on the number of articles ; for experienced authors its focus shifts towards the citation scores. this feature may be liked or not but does not make the h - index an inconsistent and inappropriate indicator, as the authors claim.
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arxiv:1109.5520
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one of the main problem in prediction theory of discrete - time second - order stationary processes $ x ( t ) $ is to describe the asymptotic behavior of the best linear mean squared prediction error in predicting $ x ( 0 ) $ given $ x ( t ), $ $ - n \ le t \ le - 1 $, as $ n $ goes to infinity. this behavior depends on the regularity ( deterministic or nondeterministic ) and on the dependence structure of the underlying observed process $ x ( t ) $. in this paper we consider this problem both for deterministic and nondeterministic processes and survey some recent results. we focus on the less investigated case - deterministic processes. it turns out that for nondeterministic processes the asymptotic behavior of the prediction error is determined by the dependence structure of the observed process $ x ( t ) $ and the differential properties of its spectral density $ f $, while for deterministic processes it is determined by the geometric properties of the spectrum of $ x ( t ) $ and singularities of its spectral density $ f $.
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arxiv:2210.06603
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small ubiquitin - related modifier ( sumo ) proteins are widely expressed in eukaryotic cells, which are reversibly coupled to their substrates by motif recognition, called sumoylation. two interesting questions are 1 ) how many potential sumo substrates may be included in mammalian proteomes, such as human and mouse, 2 ) and given a sumo substrate, can we recognize its sumoylation sites? to answer these two questions, previous prediction systems of sumo substrates mainly adopted the pattern recognition methods, which could get high sensitivity with relatively too many potential false positives. so we use phylogenetic conservation between mouse and human to reduce the number of potential false positives.
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arxiv:q-bio/0409011
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we obtain the exact energy spectra and corresponding wave functions of the radial schr \ " odinger equation ( rse ) for any ( n, l ) state in the presence of a combination of psudoharmonic, coulomb and linear confining potential terms using an exact analytical iteration method. the interaction potential model under consideration is cornell - modified plus harmonic ( cmph ) type which is a correction form to the harmonic, coulomb and linear confining potential terms. it is used to investigates the energy of electron in spherical quantum dot and the heavy quarkonia ( qq - onia ).
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arxiv:1110.0340
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linear elastic fracture mechanics ( lefm ) provides a consistent framework to evaluate quantitatively the energy flux released to the tip of a growing crack. still, the way in which the crack selects its velocity in response to this energy flux remains far from completely understood. to uncover the underlying mechanisms, we experimentally studied damage and dissipation processes that develop during the dynamic failure of polymethylmethacrylate ( pmma ), classically considered as the archetype of brittle amorphous materials. we evidenced a well - defined critical velocity along which failure switches from nominally - brittle to quasi - brittle, where crack propagation goes hand in hand with the nucleation and growth of microcracks. via post - mortem analysis of the fracture surfaces, we were able to reconstruct the complete spatiotemporal microcracking dynamics with micrometer / nanosecond resolution. we demonstrated that the true local propagation speed of individual crack fronts is limited to a fairly low value, which can be much smaller than the apparent speed measured at the continuum - level scale. by coalescing with the main front, microcracks boost the macroscale velocity through an acceleration factor of geometrical origin. we discuss the key role of damage - related internal variables in the selection of macroscale fracture dynamics.
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arxiv:1304.6283
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we combine matrix - product state ( mps ) and mean - field ( mf ) methods to model the real - time evolution of a three - dimensional ( 3d ) extended hubbard system formed from one - dimensional ( 1d ) chains arrayed in parallel with weak coupling in - between them. this approach allows us to treat much larger 3d systems of correlated fermions out - of - equilibrium over a much more extended real - time domain than previous numerical approaches. we deploy this technique to study the evolution of the system as its parameters are tuned from a charge - density wave ( cdw ) phase into the superconducting ( sc ) regime, which allows us to investigate the formation of transient non - equilibrium sc. in our ansatz, we use mps solutions for chains as input for a self - consistent time - dependent mf scheme. in this way, the 3d problem is mapped onto an effective 1d hamiltonian that allows us to use the mps efficiently to perform the time evolution, and to measure the bcs order parameter as a function of time. our results confirm previous findings for purely 1d systems that for such a scenario superconductivity forms in a transient state.
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arxiv:2207.09841
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we provide a quantitative description of the evolution of memory from the apparently random markovian dynamics of a pair of optically trapped colloidal microparticles in water. the particles are trapped in very close proximity of each other so that the resultant hydrodynamic interactions lead to non - markovian signatures manifested by the double exponential auto - correlation function for the brownian motion of each particle. in connection with the emergence of memory in this system, we quantify the storage of energy and demonstrate that a pair of markovian particles - confined in individual optical traps in a viscous fluid - can be described in the framework of a single brownian particle in a viscoelastic medium. we define and quantify the equivalent storage and loss moduli of the two - particle system, and show experimentally that the memory effects reduce with increasing particle separation and increase with a skewed stiffness ratio between the traps.
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arxiv:1808.04796
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we exploit the superb resolution of the new hst / acs mosaic image of m51 to select a large sample of young ( < 1 gyr ) star clusters in the spiral disk, based on their sizes. the image covers the entire spiral disk in b, v, i and h _ alpha, at a resolution of 2 pc per pixel. the surface density distribution of 4357 resolved clusters shows that the clusters are more correlated with clouds than with stars, and we find a hint of enhanced cluster formation at the corotation radius. the radius distribution of a sample of 769 clusters with more accurate radii suggests that young star clusters have a preferred effective radius of ~ 3 pc, which is similar to the preferred radius of the much older gcs. however, in contrast to the gcs, the young clusters in m51 do not show a relation between radius and galactocentric distance. this means that the clusters did not form in tidal equilibrium with their host galaxy, nor that their radius is related to the ambient pressure.
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arxiv:astro-ph/0605022
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portfolio optimization is a critical area in finance, aiming to maximize returns while minimizing risk. metaheuristic algorithms were shown to solve complex optimization problems efficiently, with genetic algorithms and particle swarm optimization being among the most popular methods. this paper introduces an innovative approach to portfolio optimization that incorporates pre - assignment to limit the search space for investor preferences and better results. additionally, taking margin trading strategies in account and using a rare performance ratio to evaluate portfolio efficiency. through an illustrative example, this paper demonstrates that the metaheuristic - based methodology yields superior risk - adjusted returns compared to traditional benchmarks. the results highlight the potential of metaheuristics with help of assets filtering in enhancing portfolio performance in terms of risk adjusted return.
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arxiv:2503.15965
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motivated by the closest major merger, the antennae galaxies ( ngc4038 / 4039 ), we want to improve our genetic algorithm based modeling code minga ( theis 1999 ). the aim is to reveal the major interaction and galaxy parameters, e. g. orbital information and halo properties of such an equal mass merger system. together with the sophisticated search strategy of minga, one needs fast and reliable models in order to investigate the high dimensional parameter space of this problem. therefore we use a restricted n - body code which is based on the approach by toomre & toomre ( 1972 ), however with some refinements like consistent orbits of extended dark matter halos. recently also dynamical friction was included to this code ( petsch 2007 ). while a good description for dynamical friction was found for mass ratios up to q = 1 / 3 ( petsch & theis 2008 ), major merger systems were only imperfectly remodeled. here we show recent improvements for a major merger system by including mass - loss and using nfw halos.
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arxiv:0811.2145
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according to the fireball model grbs are produced when a relativistic flow is dissipated by shocks. the questions how does a grb ' s " inner engine " accelerates and collimated the relativistic flow is today the most interesting ( and most difficult ) open question concerning grbs. we summarize, here, the known constrains on the " inner engines ". these constrains arise mostly from the temporal structure seen in the light curves of grbs. we discuss the well - known no go theorem : an explosive source cannot produce a variable grb. we show that various attempts to find a way around this theorem are rules out by new observational data : similarity between pulse width and pulse intervals and a correlation between a pulse and the preceding interval. we show that a simple toy model explains these features in terms of the internal shocks model. we discuss the implications of these findings to grbs ' inner engines.
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arxiv:astro-ph/0202403
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we show that technique of dyson equation in wave multiple scattering by spatially disordered discrete medium statistical theory leads directly to a dielectric permittivity tensor, which is characterized by spatial dispersion and obeys the generalized lorentz - lorenz formula. introduced via this spatial dispersion an effective magnetic permeability demonstrates the diamagnetic property in limit of independent strongly reflected non - magnetic small spherical particles in accordance with earlier intuitive predictions. the revealed physical nature of the effective diamagnetic property consists in that electric and magnetic dipoles induced in a particle by wave scattering give different contribution into the transverse and longitudinal components of the effective dielectric permittivity. besides as appeared the diamagnetism under study is enhanced by appearance of additional effective dielectric displacement current in the medium.
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arxiv:1009.4770
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this paper studies the applicability of evolutionary algorithms, particularly, the evolution strategies family in order to estimate a degradation parameter in the shear design of reinforced concrete members. this problem represents a great computational task and is highly relevant in the framework of the structural engineering that for the first time is solved using genetic algorithms. you are viewing a draft, the authors appreciate corrections, comments and suggestions to this work.
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arxiv:1401.5054
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in this paper, we study $ \ mathcal { n } = 1 $ supersymmetric theories in four dimensions in presence of a boundary. we demonstrate that it is possible to preserve half the supersymmetry of the original theory by suitably modifying it in presence of a boundary. this is done by adding new boundary terms to the original action, such that the supersymmetric variation of the new terms exactly cancels the boundary terms generated by the supersymmetric transformation of the original bulk action. we also analyze the boundary projections of such supercharges used in such a theory. we study super - yang - mills theories in presence of a boundary using these results. finally, we study the born - infeld action in presence of a boundary. we analyse the boundary effects for the born - infeld action coupled to a background dilaton and an axion field. we also analyse the boundary effects for an non - abelian born - infeld action. we explicitly construct the actions for these systems in presence of a boundary. this action preserves half of the original supersymmetry.
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arxiv:1502.07717
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dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at sqrt ( s ) = 7 tev, at the cern lhc. the event sample, recorded with the cms detector, corresponds to an integrated luminosity of 36 inverse picobarns. the data are found to be in good agreement with the predictions of perturbative qcd, and yield no evidence of quark compositeness. with a modified frequentist approach, a lower limit on the contact interaction scale for left - handed quarks of lambda = 5. 6 tev ( 6. 7 tev ) for destructive ( constructive ) interference is obtained at the 95 % confidence level.
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arxiv:1102.2020
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the growing demand for dynamic, user - centric data analysis and visualization is evident across domains like healthcare, finance, and research. traditional visualization tools often fail to meet individual user needs due to their static and predefined nature. to address this gap, text2insight is introduced as an innovative solution that delivers customized data analysis and visualizations based on user - defined natural language requirements. leveraging a multi - model architecture, text2insight transforms user inputs into actionable insights and dynamic visualizations. the methodology begins with analyzing the input dataset to extract structural details such as columns and values. a pre - trained llama3 model converts the user ' s natural language query into an sql query, which is further refined using a named entity recognition ( ner ) model for accuracy. a chart predictor determines the most suitable visualization type, while the llama3 model generates insights based on the sql query ' s results. the output is a user - friendly and visually informative chart. to enhance analysis capabilities, the system integrates a question - answering model and a predictive model using the bert framework. these models provide insights into historical data and predict future trends. performance evaluation of text2insight demonstrates its effectiveness, achieving high accuracy ( 99 % ), precision ( 100 % ), recall ( 99 % ), and f1 - score ( 99 % ), with a bleu score of 0. 5. the question - answering model attained an accuracy of 89 % and the predictive model achieved 70 % accuracy. these results validate text2insight as a robust and viable solution for transforming natural language text into dynamic, user - specific data analysis and visualizations.
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arxiv:2412.19718
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five new planets orbiting g and k dwarfs have emerged from the magellan velocity survey. these companions are jovian - mass planets in eccentric ( e \ geq 0. 24 ) intermediate and long - period orbits. hd 86226b orbits a solar metallicity g2 dwarf. the mp sin i mass of the planet is 1. 5 mjup, the semi - major axis is 2. 6 au, and the eccentricity 0. 73. hd 129445b orbits a metal rich g6 dwarf. the minimum mass of the planet is mp sin i = 1. 6 mjup, the semi - major axis is 2. 9 au, and the eccentricity 0. 70. hd 164604b orbits a k2 dwarf. the mp sin i mass is 2. 7 mjup, semi - major axis is 1. 3 au, and the eccentricity is 0. 24. hd 175167b orbits a metal rich g5 star. the mp sin i mass is 7. 8 mjup, the semi - major axis is 2. 4 au, and the eccentricity 0. 54. hd 152079b orbits a g6 dwarf. the mp sin i mass of the planet is 3 mjup, the semi - major axis is 3. 2 au, and the eccentricity is 0. 60.
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arxiv:1001.4093
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we show that for all positive beta the semigroups of beta - dyson brownian motions of different dimensions are intertwined. the proof relates beta - dyson brownian motions directly to jack symmetric polynomials and omits an approximation of the former by discrete space markov chains, thereby disposing of the technical assumption beta > 1 in [ gs ]. the corresponding results for beta - dyson ornstein - uhlenbeck processes are also presented.
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arxiv:1608.01597
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with the continuous increase in the size and complexity of machine learning models, the need for specialized hardware to efficiently run such models is rapidly growing. to address such a need, silicon - photonic - based neural network ( sp - nn ) accelerators have recently emerged as a promising alternative to electronic accelerators due to their lower latency and higher energy efficiency. not only can sp - nns alleviate the fan - in and fan - out problem with linear algebra processors, their operational bandwidth can match that of the photodetection rate ( typically 100 ghz ), which is at least over an order of magnitude faster than electronic counterparts that are restricted to a clock rate of a few ghz. unfortunately, the underlying silicon photonic devices in sp - nns suffer from inherent optical losses and crosstalk noise originating from fabrication imperfections and undesired optical couplings, the impact of which accumulates as the network scales up. consequently, the inferencing accuracy in an sp - nn can be affected by such inefficiencies - - e. g., can drop to below 10 % - - the impact of which is yet to be fully studied. in this paper, we comprehensively model the optical loss and crosstalk noise using a bottom - up approach, from the device to the system level, in coherent sp - nns built using mach - zehnder interferometer ( mzi ) devices. the proposed models can be applied to any sp - nn architecture with different configurations to analyze the effect of loss and crosstalk. such an analysis is important where there are inferencing accuracy and scalability requirements to meet when designing an sp - nn. using the proposed analytical framework, we show a high power penalty and a catastrophic inferencing accuracy drop of up to 84 % for sp - nns of different scales with three known mzi mesh configurations ( i. e., reck, clements, and diamond ) due to accumulated optical loss and crosstalk noise.
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arxiv:2308.03249
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we provide a rigorous treatment of continuous limits for various generalizations of the pentagram map on polygons in $ \ mathbb { rp } ^ d $ by means of quantum calculus. describing this limit in detail for the case of the short - diagonal pentagram map, we verify that this construction yields the $ ( 2, d + 1 ) $ - kdv equation, and moreover, the lax form of the pentagram map in the limit is proved to become the lax representation of the corresponding kdv system. more generally, we introduce the $ \ chi $ - pentagram map, a geometric construction defining curve evolutions by directly taking intersections of subspaces through specified points. we show that its different configurations yield certain other kdv equations and provide an argument towards disproving the conjecture that any kdv - type equation can be discretized through pentagram - type maps.
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arxiv:2010.00723
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can the causal effects estimated in an experiment be generalized to real - world scenarios? this question lies at the heart of social science studies. external validity primarily assesses whether experimental effects persist across different settings, implicitly presuming the consistency of experimental effects with their real - life counterparts. however, we argue that this presumed consistency may not always hold, especially in experiments involving multi - dimensional decision processes, such as conjoint experiments. we introduce a formal model to elucidate how attention and salience effects lead to three types of inconsistencies between experimental findings and real - world phenomena : amplified effect magnitude, effect sign reversal, and effect importance reversal. we derive testable hypotheses from each theoretical outcome and test these hypotheses using data from various existing conjoint experiments and our own experiments. drawing on our theoretical framework, we propose several recommendations for experimental design aimed at enhancing the generalizability of survey experiment findings.
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arxiv:2405.06779
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star - forming galaxies produce gamma - rays primarily via pion production, resulting from inelastic collisions between cosmic ray protons and the interstellar medium ( ism ). the dense ism and high star formation rates of luminous and ultra - luminous infrared galaxies ( lirgs and ulirgs ) imply that they should be strong gamma - ray emitters, but so far only two lirgs have been detected. theoretical models for their emission depend on the unknown fraction of cosmic ray protons that escape these galaxies before interacting. we analyze fermi - lat data for 82 of the brightest iras lirgs and ulirgs. we examine each system individually and carry out a stacking analysis to constrain their gamma - ray fluxes. we report the detection of the nearest ulirg arp 220 ( ~ 4. 6sigma ). we observe a gamma - ray flux ( 0. 8 - - 100 gev ) of 2. 4e - 10 phot cm ^ - 2 s ^ - 1 with photon index of 2. 23 ( 8. 2e10 ^ 41 ergs s ^ - 1 at 77 mpc ) we also derive upper limits for the stacked lirgs and ulirgs. the gamma - ray luminosity of arp ~ 220 and the stacked upper limits agree with calorimetric predictions for dense star - forming galaxies. with the detection of arp 220, we extend the gamma - ray - - ir luminosity correlation to the high luminosity regime with log ( l _ [ 0. 1 - 100 gev ] ) = 1. 25log ( l _ [ 8 - 1000 ] ) + 26. 7 as well as the gamma - ray - - radio continuum luminosity correlation with log ( l _ [ 0. 1 - 100 gev ] ) = 1. 22log ( l _ [ 1. 4 ghz ] ) + 13. 3. the current survey of fermi - lat is on the verge of detecting more lirgs / ulirgs in the local universe, and we expect even more detections with deeper fermi - lat observations or the next generation of gamma - ray detectors.
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arxiv:1603.06949
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we investigate shear and interface modes excited in neutron stars with an elastic crust in the full general relativistic framework and compare them to the results obtained within the relativistic cowling approximation. we observe that the cowling approximation has virtually no impact on the frequencies or the eigenfunctions of the shear modes ; in contrast, the interface modes that arise due to the discontinuities of the shear modulus experience a considerable shift in frequency when applying the cowling approximation. furthermore, we extend a scheme based on the properties of the phase of amplitude ratios, which allows us to estimate the damping times of slowly damped modes ; our extension can provide an estimation of the damping time even if the features of the amplitude ratio are incomplete or if some of them violate the underlying linearity assumption. the proposed scheme is also computationally less expensive and numerically more robust and we provide accurate estimates as well as lower bounds for damping times of shear and interface modes. we estimate the damping times also via the quadrupole formula and find that it provides good order - of - magnitude estimates.
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arxiv:2411.03940
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experimental realizations of trapping bose einstein condensate lead to a hamiltonian system of a classical particle bouncing off a convex scatterer in the field of an attracting potential. it is shown by application of kam theory that under some natural conditions there exists positive measure of quasiperiodic solutions near the boundary.
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arxiv:2104.03357
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deep operator network ( deeponet ) is a neural network framework for learning nonlinear operators such as those from ordinary differential equations ( odes ) describing complex systems. multiple - input deep neural operators ( mionet ) extended deeponet to allow multiple input functions in different banach spaces. mionet offers flexibility in training dataset grid spacing, without constraints on output location. however, it requires offline inputs and cannot handle varying sequence lengths in testing datasets, limiting its real - time application in dynamic complex systems. this work redesigns mionet, integrating long short term memory ( lstm ) to learn neural operators from time - dependent data. this approach overcomes data discretization constraints and harnesses lstm ' s capability with variable - length, real - time data. factors affecting learning performance, like algorithm extrapolation ability are presented. the framework is enhanced with uncertainty quantification through a novel bayesian method, sampling from mionet parameter distributions. consequently, we develop the b - lstm - mionet, incorporating lstm ' s temporal strengths with bayesian robustness, resulting in a more precise and reliable model for noisy datasets.
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arxiv:2311.16519
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hibiscus ( helium - inflated beam improvement setup that cools and undermines spreads ), a new radiofrequency quadrupole cooler - buncher device has been developed and commissioned offline at the ion guide isotope separator on - line ( igisol ) facility in jyv \ " askyl \ " a in finland, as an in - kind contribution for the facility for antiproton and ion research facility. hibiscus improves the ion optical properties of incident low - energy 6 ~ kev beams with the option to have it ultimately extracted in temporally short bunches ( $ < 1 $ ~ $ \ mu $ s ). this paper provides technical descriptions of its main characteristics, along with a set of optimum working parameters and performance in terms of transmission efficiency, longitudinal energy spread of the cooled ions and temporal width of the extracted bunches.
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arxiv:2501.09764
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the dicke model famously exhibits a phase transition to a superradiant phase with a macroscopic population of photons and is realized in multiple settings in open quantum systems. in this work, we study a variant of the dicke model where the cavity mode is lossy due to the coupling to a markovian environment while the atomic mode is coupled to a colored bath. we analytically investigate this model by inspecting its low - frequency behavior via the schwinger - keldysh field theory and carefully examine the nature of the corresponding superradiant phase transition. integrating out the fast modes, we can identify a simple effective theory allowing us to derive analytical expressions for various critical exponents, including those, such as the dynamical critical exponent, that have not been previously considered. we find excellent agreement with previous numerical results when the non - markovian bath is at zero temperature ; however, contrary to these studies, our low - frequency approach reveals that the same exponents govern the critical behavior when the colored bath is at finite temperature unless the chemical potential is zero. furthermore, we show that the superradiant phase transition is classical in nature, while it is genuinely non - equilibrium. we derive a fractional langevin equation and conjecture the associated fractional fokker - planck equation that capture the system ' s long - time memory as well as its non - equilibrium behavior. finally, we consider finite - size effects at the phase transition and identify the finite - size scaling exponents, unlocking a rich behavior in both statics and dynamics of the photonic and atomic observables.
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arxiv:1910.04319
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vertically thickened bars, observed in the form of boxy / peanut ( b / p ) bulges, are found in the majority of massive barred disc galaxies in the local universe, including our own. b / p bulges indicate that their host bars have suffered violent bending instabilities driven by anisotropic velocity distributions. we investigate for the first time how the frequency of b / p bulges in barred galaxies evolves from $ z = 1 $ to $ z \ approx 0 $, using a large sample of non - edge - on galaxies with masses $ m _ { \ star } > 10 ^ { 10 } \ : m _ { \ odot } $, selected from the hst cosmos survey. we find the observed fraction increases from $ 0 ^ { + 3. 6 } _ { - 0. 0 } \ % $ at $ z = 1 $ to $ 37. 8 ^ { + 5. 4 } _ { - 5. 1 } \ % $ at $ z = 0. 2 $. we account for problems identifying b / p bulges in galaxies with low inclinations and unfavourable bar orientations, and due to redshift - dependent observational biases with the help of a sample from the sloan digital sky survey, matched in resolution, rest - frame band, signal - to - noise ratio and stellar mass and analysed in the same fashion. from this, we estimate that the true fraction of barred galaxies with b / p bulges increases from $ \ sim 10 \ % $ at $ z \ approx 1 $ to $ \ sim 70 \ % $ at $ z = 0 $. in agreement with previous results for nearby galaxies, we find a strong dependence of the presence of a b / p bulge on galaxy stellar mass. this trend is observed in both local and high - redshift galaxies, indicating that it is an important indicator of vertical instabilities across a large fraction of the age of the universe. we propose that galaxy formation processes regulate the thickness of galaxy discs, which in turn affect which galaxies experience violent bending instabilities of the bar.
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arxiv:1910.04768
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asymptotic expressions of the mutual information between any discrete input and the corresponding output of the scalar additive white gaussian noise channel are presented in the limit as the signal - to - noise ratio ( snr ) tends to infinity. asymptotic expressions of the symbol - error probability ( sep ) and the minimum mean - square error ( mmse ) achieved by estimating the channel input given the channel output are also developed. it is shown that for any input distribution, the conditional entropy of the channel input given the output, mmse and sep have an asymptotic behavior proportional to the gaussian q - function. the argument of the q - function depends only on the minimum euclidean distance ( med ) of the constellation and the snr, and the proportionality constants are functions of the med and the probabilities of the pairs of constellation points at med. the developed expressions are then generalized to study the high - snr behavior of the generalized mutual information ( gmi ) for bit - interleaved coded modulation ( bicm ). by means of these asymptotic expressions, the long - standing conjecture that gray codes are the binary labelings that maximize the bicm - gmi at high snr is proven. it is further shown that for any equally spaced constellation whose size is a power of two, there always exists an anti - gray code giving the lowest bicm - gmi at high snr.
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arxiv:1212.6526
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the large anomalous hall effect ( ahe ) in antiferromagnetic ( af ) materials arises from symmetry breaking equivalent to a ferromagnetic ( fm ) state. consequently, this suggests that the observed ahe is induced by the intrinsic mechanism of the band structure effect, which in turn induces dissipationless transverse conductivity. confirmation of impurity - insensitive anomalous hall conductivity ( ahc ) is crucial to conclude this interpretation ; however, experimental investigations in af materials are limited by the lack of high quality systems. in this study, we show that the af material nbmnp, which exhibits a large ahe, offers a high quality single crystal. our findings clearly revealed that the large ahc and the tiny net magnetization of $ \ sim10 ^ { - 3 } \ mu _ { \ mathrm { b } } $ / mn are inherent in this material, irrespective of disorder. nbmnp is a novel af material that generates fm responses in the regime where there is less impurity scattering.
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arxiv:2403.05058
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the grothendieck construction is a process to form a single category from a diagram of small categories. in this paper, we extend the definition of the grothendieck construction to diagrams of small categories enriched over a symmetric monoidal category satisfying certain conditions. symmetric monoidal categories satisfying the conditions in this paper include the category of $ k $ - modules over a commutative ring $ k $, the category of chain complexes, the category of simplicial sets, the category of topological spaces, and the category of modern spectra. in particular, we obtain a generalization of the orbit category construction in [ math / 0312214 ]. we also extend the notion of graded categories and show that the grothendieck construction takes values in the category of graded categories. our definition of graded category does not require any coproduct decompositions and generalizes $ k $ - linear graded categories indexed by small categories defined by lowen. there are two popular ways to construct functors from the category of graded categories to the category of oplax functors. one of them is the smash product construction defined and studied in [ math / 0312214, 0807. 4706, 0905. 3884 ] for $ k $ - linear categories and the other one is the fiber functor. we construct extensions of these functors for enriched categories and show that they are ` ` right adjoint ' ' to the grothendieck construction in suitable senses. as a byproduct, we obtain a new short description of small enriched categories.
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arxiv:0907.0061
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the notion of hochschild homology of a dg algebra admits a natural dualization, the cohochschild homology of a dg coalgebra, introduced in arxiv : 0711. 1023 by hess, parent, and scott as a tool to study free loop spaces. in this article we prove " agreement " for cohochschild homology, i. e., that the cohochschild homology of a dg coalgebra $ c $ is isomorphic to the hochschild homology of the dg category of appropriately compact $ c $ - comodules, from which morita invariance of cohochschild homology follows. generalizing the dg case, we define the topological cohochschild homology ( cothh ) of coalgebra spectra, of which suspension spectra are the canonical examples, and show that cothh of the suspension spectrum of a space $ x $ is equivalent to the suspension spectrum of the free loop space on $ x $, as long as $ x $ is a nice enough space ( for example, simply connected. ) based on this result and on a quillen equivalence established by the authors in arxiv : 1402. 4719, we prove that " agreement " holds for cothh as well.
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arxiv:1811.06508
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infrared studies of asymptotic giant branch ( agb ) stars are critical to our understanding of the formation of cosmic dust. in this investigation, we explore the mid - to - far - infrared emission of oxygen rich agb star rt virginis. this optically thin dusty environment has unusual spectral features when compared to other stars in its class. to explore this enigmatic object we use the 1 - d radiative transfer modeling code dusty. modeled spectra are compared with observations from the infrared space observatory ( iso ), infrared astronomical satellite ( iras ), the herschel space observatory and a host of other sources to determine the properties of rt vir ' s circumstellar material. our models suggest a set of two distant and cool dust shells at low optical depths ( tauv, inner = 0. 16, tauv, outer = 0. 06 ), with inner dust temperatures : t1 = 330k, t3 = 94k. overall, these dust shells exhibit a chemical composition consistent with dust typically found around o - rich agb stars. however, the distribution of materials differs significantly. the inner shell consists of a mixture of silicates, al2o3, feo, and fe, while the outer shell primarily contains crystalline al2o3 polymorphs. this chemical change is indicative of two distinct epochs of dust formation around rt vir. these changes in dust composition are driven by either changes in the pressure - temperature conditions around the star, or by a decrease in the c / o ratio due to hot - bottom burning.
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arxiv:2412.01726
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the power suppression at largest scale in the cmb tt powerspectrum might imply the occurrence of a pre - inflationary bounce. we calculate the circularly polarized gravitational wave, leaded by the gravitational chern - simons term which universally appears in particle physics and string theory, in an inflationary background with the pre - inflationary bounce. the circularly polarized gravitational wave will induce tb and eb correlations at cmb last scatting surface. we find that although the bb powerspectrum at largest scale is also suppressed, the tb and eb powerspectra at corresponding scales may be enhanced.
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arxiv:1409.7153
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we derive heuristically approximate formulas for the negative $ k $ - - moments $ m _ { - k } ( x ) $ of the gaps between consecutive primes $ < x $ represented directly by $ \ pi ( x ) $ - - - the number of primes up to $ x $. in particular we propose an analytical formula for the sum of reciprocals of gaps between consecutive primes $ < x : ~ m _ { - 1 } ( x ) \ sim \ frac { \ pi ^ 2 ( x ) } { x - 2 \ pi ( x ) } \ log \ big ( \ frac { x } { 2 \ pi ( x ) } \ big ) \ sim x \ log \ log ( x ) / \ log ^ 2 ( x ) $. we illustrate obtained results by the enormous computer data up to $ x = 4 \ times 10 ^ { 18 } $.
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arxiv:1805.04940
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we discuss methods for the calculation of disconnected diagrams and their application to various form factors of the nucleon. in particular, we present preliminary results for the strange contribution to the scalar and axial form factors, calculated with n _ f = 2 dynamical flavors of wilson fermions on an anisotropic lattice.
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arxiv:0710.5536
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we suggest that neutron stars experienced at birth three related physical changes, which may originate in magneto - rotational instabilities : ( i ) an increase in period from the initial value p _ 0 to the current value p _ s, implying a change of rotational energy \ delta e _ rot ; ( ii ) an exponential decay of its magnetic field from the initial value b _ 0 to the current surface value b _ s, implying a change of radiative energy \ delta e _ rad ; and ( iii ) an increase of space velocity from the initial value v _ 0 to the current value v, implying a change of kinetic energy \ delta e _ kin. these changes are assumed to be connected by \ delta e _ rad + \ delta e _ kin = \ delta e _ rot. this means that the radiation loss and increase of kinetic energy are both at the expense of a rotational energy loss. it is shown that this energy conversion occurs during times of order of 10 ^ ( - 4 ) s if the neutron stars are born with magnetic fields in the range of 10 ^ ( 15 ) - 10 ^ ( 16 ) g and initial periods in range 1 - 20 ms. it is shown that the birth accelerations of neutron stars are of the order of 10 ^ ( 8 ) g.
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arxiv:1302.1275
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extremely large telescopes ( elts ) provide an opportunity to observe surface inhomogeneities for ultracool objects including m dwarfs, brown dwarfs ( bds ), and gas giant planets via doppler imaging and spectro - photometry techniques. these inhomogeneities can be caused by star spots, clouds, and vortices. star spots and associated stellar flares play a significant role in habitability, either stifling life or catalyzing abiogenesis depending on the emission frequency, magnitude, and orientation. clouds and vortices may be the source of spectral and photometric variability observed at the l / t transition of bds and are expected in gas giant exoplanets. we develop a versatile analytical framework to model and infer surface inhomogeneities which can be applied to both spectroscopic and photometric data. this model is validated against a slew of numerical simulations. using archival spectroscopic and photometric data, we infer star spot parameters ( location, size, and contrast ) and generate global surface maps for luhman 16b ( an early t dwarf and one of our solar system ' s nearest neighbors at a distance of approximately 2 pc ). we confirm previous findings that luhman 16b ' s atmosphere is inhomogeneous with time - varying features. in addition, we provide tentative evidence of longer timescale atmospheric structures such as dark equatorial and bright mid - latitude to polar spots. these findings are discussed in the context of atmospheric circulation and dynamics for ultracool dwarfs. our analytical model will be valuable in assessing the feasibility of using elts to study surface inhomogeneities of gas giant exoplanets and other ultracool objects.
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arxiv:2206.01770
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very long baseline interferometry ( vlbi ) provides the finest angular resolution of all astronomical observation techniques. however, observations with earth - based instruments are approaching fundamental limits on angular resolution. these can only be overcome by placing at least one interferometric element in space. in this paper, several concepts of spaceborne vlbi systems are discussed, including terahertz exploration and zooming - in for astrophysics ( theza ) and the black hole explorer ( bhex ). spaceborne vlbi telescopes have some of the most demanding requirements of any space science mission. the vlbi system as a whole includes globally distributed elements, each with their own functional constraints, limiting when observations can be performed. this necessitates optimisation of the system parameters in order to maximise the scientific return of the mission. presented is an investigation into how the impact of the functional constraints of a spaceborne vlbi telescope affect the overall system performance. a preliminary analysis of how these constraints can be minimised through optimisation of the spacecraft configuration and operation is also provided. a space - based vlbi simulation tool ( spacevlbi ) has been developed to model such missions and its capabilities are demonstrated throughout the paper. it is imperative that the functional constraints are considered early in the design of the future space - based vlbi systems in order to generate feasible mission concepts and to identify the key technology developments required to mitigate these limitations.
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arxiv:2503.20312
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estimating a scene reconstruction and the camera motion from in - body videos is challenging due to several factors, e. g. the deformation of in - body cavities or the lack of texture. in this paper we present endo - depth - and - motion, a pipeline that estimates the 6 - degrees - of - freedom camera pose and dense 3d scene models from monocular endoscopic videos. our approach leverages recent advances in self - supervised depth networks to generate pseudo - rgbd frames, then tracks the camera pose using photometric residuals and fuses the registered depth maps in a volumetric representation. we present an extensive experimental evaluation in the public dataset hamlyn, showing high - quality results and comparisons against relevant baselines. we also release all models and code for future comparisons.
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arxiv:2103.16525
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multi - armed bandits ( mab ) are extensively studied in various settings where the objective is to \ textit { maximize } the actions ' outcomes ( i. e., rewards ) over time. since safety is crucial in many real - world problems, safe versions of mab algorithms have also garnered considerable interest. in this work, we tackle a different critical task through the lens of \ textit { linear stochastic bandits }, where the aim is to keep the actions ' outcomes close to a target level while respecting a \ textit { two - sided } safety constraint, which we call \ textit { leveling }. such a task is prevalent in numerous domains. many healthcare problems, for instance, require keeping a physiological variable in a range and preferably close to a target level. the radical change in our objective necessitates a new acquisition strategy, which is at the heart of a mab algorithm. we propose sale - lts : safe leveling via linear thompson sampling algorithm, with a novel acquisition strategy to accommodate our task and show that it achieves sublinear regret with the same time and dimension dependence as previous works on the classical reward maximization problem absent any safety constraint. we demonstrate and discuss our algorithm ' s empirical performance in detail via thorough experiments.
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arxiv:2112.06728
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new tactile interfaces such as swell form printing or refreshable tactile displays promise to allow visually impaired people to analyze data. however, it is possible that design guidelines and familiar encodings derived from experiments on the visual perception system may not be optimal for the tactile perception system. we replicate the cleveland and mcgill study on graphical perception using swell form printing with eleven visually impaired subjects. we find that the visually impaired subjects read charts quicker and with similar and sometimes superior accuracy than in those replications. based on a group interview with a subset of participants, we describe the strategies used by our subjects to read four chart types. while our results suggest that familiar encodings based on visual perception studies can be useful in tactile graphics, our subjects also expressed a desire to use encodings designed explicitly for visually impaired people.
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arxiv:2410.08438
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the sending - or - not - sending protocol of the twin - field quantum key distribution ( tf - qkd ) has its advantage of unconditional security proof under any coherent attack and fault tolerance to large misalignment error. so far this is the only coherent - state based tf - qkd protocol that has considered finite - key effect, the statistical fluctuations. here we consider the complete finite - key effects for the protocol and we show by numerical simulation that the protocol with typical finite number of pulses in practice can produce unconditional secure final key under general attack, including all coherent attacks. it can exceed the secure distance of 500 $ km $ in typical finite number of pulses in practice even with a large misalignment error.
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arxiv:1904.00192
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we investigate spherical accretion to a rotating magnetized star in the " propeller " regime using axisymmetric resistive magnetohydrodynamic simulations. the regime is predicted to occur if the magnetospheric radius is larger than the corotation radius and smaller than the light cylinder radius. the simulations show that accreting matter is expelled from the equatorial region of the magnetosphere and that it moves away from the star in a supersonic, disk - shaped outflow. at larger radial distances the outflow slows down and becomes subsonic. the equatorial matter outflow is initially driven by the centrifugal force, but at larger distances the pressure gradient force becomes significant. we find the fraction of the bondi accretion rate which accretes to the surface of the star.
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arxiv:astro-ph/0607189
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it is shown how the hard thermal loop approximation can be used in chiral perturbation theory to study some thermal properties of goldstone bosons. hard thermal effects are first studied in the non - linear sigma model. then those results are used to obtain the thermal corrections to the transverse and longitudinal gauge field masses in the electroweak theory in the limit of a strongly interacting higgs boson.
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arxiv:hep-ph/9809273
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if m is a monoid ( e. g. the lattice z ^ d ), and g is a finite ( nonabelian ) group, then g ^ m is a compact group ; a ` multiplicative cellular automaton ' ( mca ) is a continuous transformation f : g ^ m - - > g ^ m which commutes with all shift maps, and where nearby coordinates are combined using the multiplication operation of g. we characterize when mca are group endomorphisms of g ^ m, and show that mca on g ^ m inherit a natural structure theory from the structure of g. we apply this structure theory to compute the measurable entropy of mca, and to study convergence of initial measures to haar measure.
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arxiv:math/0108084
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diffusion - limited reactions ( dlr ) are usually described within the smoluchowski theory, which neglects interactions between the diffusing components. we propose a first extension of such frame - work that incorporates excluded - volume effects, considering hard diffusing agents in the presence of an absorbing sink. for large values of the absorber - to - diffuser size ratio rs, the encounter rate obtained from the simulations is in very good agreement with a simple generalization of the smolu - chowski equation at high densities. reducing rs, the rate gets substantially depressed at interme - diate packing and become even non - monotonic for rs < < 1. concurrently with the saturation of the rate, stationary density waves set in close to the absorbing center. a mean - field, effective - potential analysis of the smoluchowski equation under crowding sheds light on the subtle link between such ordering and the slowing down of the encounter dynamics. finally, we show how an infinitesimal amount of non - reacting impurities can equally slow down dramatically the reaction.
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arxiv:1007.2529
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motivated by the observed cosmic matter distribution, we present the following conjecture : due to the formation of voids and opaque structures, the average matter density on the path of the light from the well - observed objects changes from omega _ m ~ 1 in the homogeneous early universe to omega _ m ~ 0 in the clumpy late universe, so that the average expansion rate increases along our line of sight from eds expansion ht ~ 2 / 3 at high redshifts to free expansion ht ~ 1 at low redshifts. to calculate the modified observable distance - redshift relations, we introduce a generalized dyer - roeder method that allows for two crucial physical properties of the universe : inhomogeneities in the expansion rate and the growth of the nonlinear structures. by treating the transition redshift to the void - dominated era as a free parameter, we find a phenomenological fit to the observations from the cmb anisotropy, the position of the baryon oscillation peak, the magnitude - redshift relations of type ia supernovae, the local hubble flow and the nucleosynthesis, resulting in a concordant model of the universe with 90 % dark matter, 10 % baryons, no dark energy, 15 gyr as the age of the universe and a natural value for the transition redshift z _ 0 = 0. 35. unlike a large local void, the model respects the cosmological principle, further offering an explanation for the late onset of the perceived acceleration as a consequence of the forming nonlinear structures. additional tests, such as quantitative predictions for angular deviations due to an anisotropic void distribution and a theoretical derivation of the model, can vindicate or falsify the interpretation that light propagation in voids is responsible for the perceived acceleration.
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arxiv:0711.4264
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in this paper, we study the multiplicity and concentration of the positive solutions to the following critical kirchhoff type problem : \ begin { equation * } - \ left ( \ varepsilon ^ 2 a + \ varepsilon b \ int _ { \ r ^ 3 } | \ nabla u | ^ 2 \ mathrm { d } x \ right ) \ delta u + v ( x ) u = f ( u ) + u ^ 5 \ \ { \ rm in } \ \ \ r ^ 3, \ end { equation * } where $ \ varepsilon $ is a small positive parameter, $ a $, $ b $ are positive constants, $ v \ in c ( \ mathbb { r } ^ 3 ) $ is a positive potential, $ f \ in c ^ 1 ( \ r ^ +, \ r ) $ is a subcritical nonlinear term, $ u ^ 5 $ is a pure critical nonlinearity. when $ \ varepsilon > 0 $ small, we establish the relationship between the number of positive solutions and the profile of the potential $ v $. the exponential decay at infinity of the solution is also obtained. in particular, we show that each solution concentrates around a local strict minima of $ v $ as $ \ varepsilon \ rightarrow 0 $.
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arxiv:1607.03668
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in this work, we investigate collective electronic fluctuations and, in particular, the possibility of the charge density wave ordering in an infinite - layer ndnio $ _ 2 $. we perform advanced many - body calculations for the ab - initio three - orbital model by taking into account local correlation effects, non - local charge and magnetic fluctuations, and the electron - phonon coupling. we find that in the considered material, electronic correlations are strongly orbital - and momentum - dependent. notably, the charge density wave and magnetic instabilities originate from distinct orbitals. in particular, we show that the correlation effects lead to the momentum - dependent hybridization between different orbitals, resulting in the splitting and shifting of the flat part of the ni - $ d _ { z ^ 2 } $ band. this strong renormalization of the electronic spectral function drives the charge density wave instability that is related to the intraband ni - $ d _ { z ^ 2 } $ correlations. instead, the magnetic instability stems from the ni - $ d _ { x ^ 2 - y ^ 2 } $ orbital, which remains half - filled through the redistribution of the electronic density between different bands even upon hole doping. consequently, the strength of the magnetic fluctuations remains nearly unchanged for the considered doping levels. we argue that this renormalization is not inherent to the stoichiometric case but can be induced by hole doping.
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arxiv:2311.09983
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to determine the size of an extensive air shower it is not necessary to have knowledge of the function that describes the fall - off of signal size from the shower core ( the lateral distribution function ). in this paper an analysis with a simple monte carlo model is used to show that an optimum ground parameter can be identified for each individual shower. at this optimal core distance, $ r _ \ mathrm { opt } $, the fluctuations in the expected signal, $ s ( r _ \ mathrm { opt } ) $, due to a lack of knowledge of the lateral distribution function are minimised. furthermore it is shown that the optimum ground parameter is determined primarily by the array geometry, with little dependence on the energy or zenith angle of the shower or choice of lateral distribution function. for an array such as the pierre auger southern observatory, with detectors separated by 1500 m in a triangular configuration, the optimum distance at which to measure this characteristic signal is close to 1000 m.
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arxiv:astro-ph/0608118
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large language models ( llms ) have demonstrated remarkable proficiency in mainstream academic disciplines such as mathematics, physics, and computer science. however, human knowledge encompasses over 200 specialized disciplines, far exceeding the scope of existing benchmarks. the capabilities of llms in many of these specialized fields - particularly in light industry, agriculture, and service - oriented disciplines - remain inadequately evaluated. to address this gap, we present supergpqa, a comprehensive benchmark that evaluates graduate - level knowledge and reasoning capabilities across 285 disciplines. our benchmark employs a novel human - llm collaborative filtering mechanism to eliminate trivial or ambiguous questions through iterative refinement based on both llm responses and expert feedback. our experimental results reveal significant room for improvement in the performance of current state - of - the - art llms across diverse knowledge domains ( e. g., the reasoning - focused model deepseek - r1 achieved the highest accuracy of 61. 82 % on supergpqa ), highlighting the considerable gap between current model capabilities and artificial general intelligence. additionally, we present comprehensive insights from our management of a large - scale annotation process, involving over 80 expert annotators and an interactive human - llm collaborative system, offering valuable methodological guidance for future research initiatives of comparable scope.
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arxiv:2502.14739
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pedestrian crowding occurs more frequent. as a result of the increasing pedestrian demand in public space, the limits of pedestrian spaces are of increasing interest. some research on the maximum demand that can flow through a cross - section has been presented, which mainly features simple movement base cases, low - density situations and / or a homogeneous crowd. consequently, it is currently unclear to what extent their findings apply to heterogeneous high - density crowds, which are often encountered during real - world scenarios. the crowdlimits experiment attempted to reproduce crowd movement dynamics of heterogeneous crowds experiencing higher densities than have been recorded up to this moment. here, the aim was to study the impact of the three important differences between the current laboratory studies and real - world crowd dynamics in crowded pedestrian spaces simultaneously, namely crowd heterogeneity, high densities movements, and ( more ) complex movement base cases. this study shows that there are substantial differences in the maximum sustainable flow rate, and the maximum local and global sustainable density for distinct movement base cases and flow ratios. moreover, the results provide evidence of that continuation of flow under very high densities can be recreated under laboratory conditions using a heterogeneous population of pedestrians. besides, the experimental results indicate that the maximum global flow rate decreases when the scenario becomes more difficult ( i. e. bidirectional to intersecting ) and the collision avoidance opportunities decrease ( i. e. 80 - 20 to 50 - 50 flow ratio ). thus, this paper concludes that the maximum flow rate of pedestrian infrastructures decreases with increasing complexity.
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arxiv:1908.07208
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for each $ t > 0, $ up to the number $ n = n ( t ), $ the exact estimations of all initial taylor coefficients in the class $ b _ t $ were found, where $ b _ t $ is a set of holomorphic in unit disk functions $ f, $ $ 0 < | f | < 1, $ $ f ( 0 ) = e ^ { - t }. $
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arxiv:1104.3984
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bolometric and 0. 2 - 2 kev x - ray luminosities of the hot gas haloes of simulated disc galaxies have been calculated at redshift z = 0. the treesph simulations are fully cosmological and the sample of 44 disc galaxies span a range in characteristic circular speeds of v _ c = 130 - 325 km / s. the galaxies have been obtained in simulations with a considerable range of physical parameters, varying the baryonic fraction, the gas metallicity, the meta - galactic uv field, the cosmology, the dark matter type, and also the numerical resolution. the models are found to be in agreement with the ( few ) relevant x - ray observations available at present. the amount of hot gas in the haloes is also consistent with constraints from pulsar dispersion measures in the milky way. forthcoming xmm and chandra observations should enable much more stringent tests and provide constraints on the physical parameters. we find that simple cooling flow models over - predict x - ray luminosities by up to two orders of magnitude for high ( but still realistic ) cooling efficiencies relative to the models presented here. our results display a clear trend that increasing cooling efficiency leads to decreasing x - ray luminosities at z = 0. the reason is found to be that increased cooling efficiency leads to a decreased fraction of hot gas relative to total baryonic mass inside of the virial radius at present. at gas metal abundances of a third solar this hot gas fraction becomes as low as just a few percent. we also find that most of the x - ray emission comes from the inner parts ( inner about 20 kpc ) of the hot galactic haloes. finally, we find for realistic choices of the physical parameters that disc galaxy haloes possibly were more than one order of magnitude brighter in soft x - ray emission at z = 1, than at present.
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arxiv:astro-ph/0201529
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one of the major open questions in matroid theory asks whether the $ h $ - vector $ ( h _ 0, h _ 1, \ ldots, h _ s ) $ of the broken circuit complex of a matroid $ m $ satisfies the following inequalities : $ $ h _ 0 \ leq h _ 1 \ leq \ cdots \ leq h _ { \ lfloor s / 2 \ rfloor } \ quad \ text { and } \ qua h _ i \ le h _ { s - i } \ \ text { for } \ 0 \ leq i \ leq \ lfloor s / 2 \ rfloor. $ $ this paper affirmatively answers the question for matroids that are representable over a field of characteristic zero.
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arxiv:1604.02938
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the crystal and magnetic structure of the magnetocaloric compound femnp0. 5si0. 5 have been studied by means of neutron and x - ray powder diffraction. single phase samples of nominal composition femnp0. 5si0. 5 have been prepared by the drop synthesis method. the compound crystallizes in the fe2p - type structure ( p - 62m ) with the magnetic moments aligned along the aaxis. it is found that the fe atoms are mainly situated in the tetrahedral 3g site while the mn atoms prefer the pyramidal 3f position. the material is ferromagnetic ( tc = 382 k ) and at 296 k the total magnetic moment is 4. 4 \ mu b / f. u. it is shown that the magnetic moment in the 3f site is larger ( 2. 5 \ mu b ) than in the 3g site ( 1. 9 \ mu b ).
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arxiv:1105.1942
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solar energetic particle ( sep ) events and their major subclass, solar proton events ( spes ), can have unfavorable consequences on numerous aspects of life and technology, making them one of the most harmful effects of solar activity. garnering knowledge preceding such events by studying operational data flows is essential for their forecasting. considering only solar cycle ( sc ) 24 in our previous study, sadykov et al. 2021, we found that it may be sufficient to utilize only proton and soft x - ray ( sxr ) parameters for spe forecasts. here, we report a catalog recording $ \ geq $ 10 mev $ \ geq $ 10 particle flux unit spes with their properties, spanning scs 22 - 24, using noaa ' s geostationary operational environmental satellite flux data. we report an additional catalog of daily proton and sxr flux statistics for this period, employing it to test the application of machine learning ( ml ) on the prediction of spes using a support vector machine ( svm ) and extreme gradient boosting ( xgboost ). we explore the effects of training models with data from one and two scs, evaluating how transferable a model can be across different time periods. xgboost proved to be more accurate than svms for almost every test considered, while outperforming operational swpc noaa predictions and a persistence forecast. interestingly, training done with sc 24 produces weaker tss and hss2, even when paired with sc 22 or sc 23, indicating transferability issues. this work contributes towards validating forecasts using long - spanning data - - an understudied area in sep research that should be considered to verify the cross - cycle robustness of ml - driven forecasts.
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arxiv:2303.05446
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as in the case of einstein or lovelock gravity, the action of quartic quasitopological gravity has not a well - defined variational principle. in this paper, we first introduce a surface term that makes the variation of quartic quasitopological gravity well defined. second, we present the static charged solutions of quartic quasitopological gravity in the presence of a non linear electromagnetic field. one of the branch of these solutions presents a black brane with one or two horizons or a naked singularity depending on the charge and mass of the solution. the thermodynamic of these black branes are investigated through the use of the gibbs free energy. in order to do this, we calculate the finite action by use of the counterterm method inspired by ads / cft correspondence. introducing a smarr - type formula, we also show that the conserved and thermodynamics quantities of these solutions satisfy the first law of thermodynamics. finally, we present the charged rotating black branes in $ ( n + 1 ) $ dimensions with $ k \ leq [ n / 2 ] $ rotation parameters and investigate their thermodynamics.
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arxiv:1209.0246
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personalized dialogue generation, focusing on generating highly tailored responses by leveraging persona profiles and dialogue context, has gained significant attention in conversational ai applications. however, persona profiles, a prevalent setting in current personalized dialogue datasets, typically composed of merely four to five sentences, may not offer comprehensive descriptions of the persona about the agent, posing a challenge to generate truly personalized dialogues. to handle this problem, we propose $ \ textbf { l } $ earning retrieval $ \ textbf { a } $ ugmentation for $ \ textbf { p } $ ersonalized $ \ textbf { d } $ ial $ \ textbf { o } $ gue $ \ textbf { g } $ eneration ( $ \ textbf { lapdog } $ ), which studies the potential of leveraging external knowledge for persona dialogue generation. specifically, the proposed lapdog model consists of a story retriever and a dialogue generator. the story retriever uses a given persona profile as queries to retrieve relevant information from the story document, which serves as a supplementary context to augment the persona profile. the dialogue generator utilizes both the dialogue history and the augmented persona profile to generate personalized responses. for optimization, we adopt a joint training framework that collaboratively learns the story retriever and dialogue generator, where the story retriever is optimized towards desired ultimate metrics ( e. g., bleu ) to retrieve content for the dialogue generator to generate personalized responses. experiments conducted on the convai2 dataset with rocstory as a supplementary data source show that the proposed lapdog method substantially outperforms the baselines, indicating the effectiveness of the proposed method. the lapdog model code is publicly available for further exploration. https : / / github. com / hqsiswiliam / lapdog
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arxiv:2406.18847
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in this paper, we present a natural implementation of singular value decomposition ( svd ) and polar decomposition of an arbitrary multivector in nondegenerate real and complexified clifford geometric algebras of arbitrary dimension and signature. the new theorems involve only operations in geometric algebras and do not involve matrix operations. we naturally define these and other related structures such as hermitian conjugation, euclidean space, and lie groups in geometric algebras. the results can be used in various applications of geometric algebras in computer science, engineering, and physics.
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arxiv:2404.11920
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collaboration among researchers is an essential component of the modern scientific enterprise, playing a particularly important role in multidisciplinary research. however, we continue to wrestle with allocating credit to the coauthors of publications with multiple authors, since the relative contribution of each author is difficult to determine. at the same time, the scientific community runs an informal field - dependent credit allocation process that assigns credit in a collective fashion to each work. here we develop a credit allocation algorithm that captures the coauthors ' contribution to a publication as perceived by the scientific community, reproducing the informal collective credit allocation of science. we validate the method by identifying the authors of nobel - winning papers that are credited for the discovery, independent of their positions in the author list. the method can also compare the relative impact of researchers working in the same field, even if they did not publish together. the ability to accurately measure the relative credit of researchers could affect many aspects of credit allocation in science, potentially impacting hiring, funding, and promotion decisions.
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arxiv:1408.3455
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we address multiparameter quantum estimation for coherently driven nonlinear kerr resonators in the presence of loss. in particular, we consider the realistic situation in which the parameters of interest are the loss rate and the nonlinear coupling, whereas the amplitude of the coherent driving is known and externally tunable. our results show that this driven - dissipative model is asymptotically classical, i. e. the uhlmann curvature vanishes, and the two parameters may be jointly estimated without any additional noise of quantum origin. we also find that the ultimate bound to precision, as quantified by the quantum fisher information ( qfi ), increases with the interaction time and the driving amplitude for both parameters. finally, we investigate the performance of quadrature detection, and show that for both parameters the fisher information oscillates in time, repeatedly approaching the corresponding qfi.
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arxiv:2212.05117
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we assess the local symmetry and crystal environment of trivalent terbium ions embedded in an indium tin oxide ( ito ) matrix with bixbyite structure. the \ mbox { tb $ ^ { 3 + } $ } ions tend to substitute \ mbox { in $ ^ { 3 + } $ } ions in two different cationic sites ( $ b $ and $ d $ ). density functional theory ( dft ) calculations suggest that the \ mbox { tb $ ^ { 3 + } $ } ions are mainly located at $ c _ 2 $ symmetry sites relaxing selection rules and enabling electric dipole transitions, with the $ ^ 5 \ text { d } _ 4 \ rightarrow \ leftindex ^ 7 { \ text { f } } _ 2 $ transition being the most intense, providing a red color to the light emission. photoluminescence emission spectra under uv excitation at \ qty { 83 } { \ kelvin } revealed 30 intra - 4 $ f $ transitions, which were assigned to the $ \ leftindex ^ 7 { \ text { f } } _ j $ ground multiplet of the \ mbox { tb $ ^ { 3 + } $ } ion. crystal - field analysis shows a strong alignment between calculated and observed energy levels, yielding a standard deviation of $ \ sigma = \ qty { 15. 1 } { \ centi \ per \ metre } $. we believe these results can help to understand the activation mechanisms of \ mbox { tb $ ^ { 3 + } $ } luminescent centers in transparent conductive oxides, as well as the potential to modulate \ mbox { tb $ ^ { 3 + } $ } emission color through its crystalline environment.
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arxiv:2502.08517
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