text
stringlengths 1
3.65k
| source
stringlengths 15
79
|
|---|---|
we answer in negative to the following question of boris mitjagin : is it true that a product of two nuclear operators in banach spaces can be factored through a trace class operator in a hilbert space?
|
arxiv:2105.01247
|
the interaction of light quarks and instanton liquid is analyzed at finite density of quark / baryon matter and in the phase of nonzero values of diquark ( colour ) condensate. it is shown that instanton liquid perturbation produced by such an interaction results in an essential increase of the critical value of quark chemical potential $ \ mu _ c $ which provokes the perceptible increase of quark matter density around the expected onset of the colour superconductivity phase.
|
arxiv:hep-ph/0210100
|
a joint analysis of the clustering of galaxies and their weak gravitational lensing signal is well - suited to simultaneously constrain the galaxy - halo connection as well as the cosmological parameters by breaking the degeneracy between galaxy bias and the amplitude of clustering signal. in a series of two papers, we perform such an analysis at the highest redshift ( $ z \ sim0. 53 $ ) in the literature using cmass galaxies in the sloan digital sky survey - iii baryon oscillation spectroscopic survey eleventh data release ( sdss - iii / boss dr11 ) catalog spanning 8300 ~ deg $ ^ 2 $. in this paper, we present details of the clustering and weak lensing measurements of these galaxies. we define a subsample of 400, 916 cmass galaxies based on their redshifts and stellar mass estimates so that the galaxies constitute an approximately volume - limited and similar population over the redshift range $ 0. 47 \ le z \ le 0. 59 $. we obtain a signal - to - noise ratio $ s / n \ simeq 56 $ for the galaxy clustering measurement. we also explore the redshift and stellar mass dependence of the clustering signal. for the weak lensing measurement, we use existing deeper imaging data from the cfhtls with publicly available shape and photometric redshift catalogs from cfhtlens, but only in a 105 ~ deg $ ^ 2 $ area which overlaps with boss. this restricts the lensing measurement to only 5, 084 cmass galaxies. after careful systematic tests, we find a highly significant detection of the cmass weak lensing signal, with total $ s / n \ simeq 26 $. these measurements form the basis of the halo occupation distribution and cosmology analysis presented in more et al. ( paper ii ).
|
arxiv:1311.1480
|
speech - driven facial animation is useful for a variety of applications such as telepresence, chatbots, etc. the necessary attributes of having a realistic face animation are 1 ) audio - visual synchronization ( 2 ) identity preservation of the target individual ( 3 ) plausible mouth movements ( 4 ) presence of natural eye blinks. the existing methods mostly address the audio - visual lip synchronization, and few recent works have addressed the synthesis of natural eye blinks for overall video realism. in this paper, we propose a method for identity - preserving realistic facial animation from speech. we first generate person - independent facial landmarks from audio using deepspeech features for invariance to different voices, accents, etc. to add realism, we impose eye blinks on facial landmarks using unsupervised learning and retargets the person - independent landmarks to person - specific landmarks to preserve the identity - related facial structure which helps in the generation of plausible mouth shapes of the target identity. finally, we use lsgan to generate the facial texture from person - specific facial landmarks, using an attention mechanism that helps to preserve identity - related texture. an extensive comparison of our proposed method with the current state - of - the - art methods demonstrates a significant improvement in terms of lip synchronization accuracy, image reconstruction quality, sharpness, and identity - preservation. a user study also reveals improved realism of our animation results over the state - of - the - art methods. to the best of our knowledge, this is the first work in speech - driven 2d facial animation that simultaneously addresses all the above - mentioned attributes of a realistic speech - driven face animation.
|
arxiv:2005.12318
|
a negotiating team is a group of two or more agents who join together as a single negotiating party because they share a common goal related to the negotiation. since a negotiating team is composed of several stakeholders, represented as a single negotiating party, there is need for a voting rule for the team to reach decisions. in this paper, we investigate the problem of strategic voting in the context of negotiating teams. specifically, we present a polynomial - time algorithm that finds a manipulation for a single voter when using a positional scoring rule. we show that the problem is still tractable when there is a coalition of manipulators that uses a x - approval rule. the coalitional manipulation problem becomes computationally hard when using borda, but we provide a polynomial - time algorithm with the following guarantee : given a manipulable instance with k manipulators, the algorithm finds a successful manipulation with at most one additional manipulator. our results hold for both constructive and destructive manipulations.
|
arxiv:2107.14097
|
we consider ii $ _ 1 $ factors $ m $ which can be realized as inductive limits of subfactors, $ n _ n \ nearrow m $, having spectral gap in $ m $ and satisfying the bi - commutant condition $ ( n _ n ' \ cap m ) ' \ cap m = n _ n $. examples are the enveloping algebras associated to non - gamma subfactors of finite depth, as well as certain crossed products of mcduff factors by amenable groups. we use deformation / rigidity techniques to obtain classification results for such factors.
|
arxiv:0910.2241
|
in this paper, we use the concept of excursion sets for the extrapolation of stationary random fields. doing so, we define excursion sets for the field and its linear predictor, and then minimize the expected volume of the symmetric difference of these sets under the condition that the univariate distributions of the predictor and of the field itself coincide. we illustrate the new approach on gaussian random fields.
|
arxiv:2108.12481
|
we propose affine concept editing ( ace ) as an approach for steering language models ' behavior by intervening directly in activations. we begin with an affine decomposition of model activation vectors and show that prior methods for steering model behavior correspond to subsets of terms of this decomposition. we then provide a derivation of ace and use it to control refusal behavior on ten different models, including llama 3 70b. ace combines affine subspace projection and activation addition to reliably control the model ' s refusal responses across prompt types. we evaluate the results using llm - based scoring on a collection of harmful and harmless prompts. our experiments demonstrate that ace consistently achieves more precise control over model behavior than existing methods and generalizes to models where directional ablation via affine subspace projection alone produces incoherent outputs. code for reproducing our results is available at https : / / github. com / eleutherai / steering - llama3.
|
arxiv:2411.09003
|
we present the theory of a supersymmetric ghost condensate coupled to n = 1 supergravity. this is accomplished using a general formalism for constructing locally supersymmetric higher - derivative chiral superfield actions. the theory admits a ghost condensate vacuum in de sitter spacetime. expanded around this vacuum, the scalar sector of the theory is shown to be ghost - free with no spatial gradient instabilities. by direct calculation, the fermion sector is found to consist of a massless chiral fermion and a massless gravitino. by analyzing the supersymmetry transformations, we find that the chiral fermion transforms inhomogeneously, indicating that the ghost condensate vacuum spontaneously breaks local supersymmetry with this field as the goldstone fermion. although potentially able to get a mass through the super - higgs effect, the vanishing superpotential in the ghost condensate theory renders the gravitino massless. thus local supersymmetry is broken without the super - higgs effect taking place. this is in agreement with, and gives an explanation for, the direct calculation.
|
arxiv:1212.2185
|
the surprising discovery of tripling the superconducting critical temperature of kfe $ _ 2 $ as $ _ 2 $ at high pressures issued an intriguing question of how the superconductivity in the collapsed tetragonal phase differs from that in the non - collapsed phases of fe - based superconductors. here we report $ ^ { 89 } $ y nuclear magnetic resonance study of yfe $ _ 2 $ ge $ _ { x } $ si $ _ { 2 - x } $ compounds whose electronic structure is similar to that of iron - pnictide collapsed tetragonal phases already at ambient pressure. fe ( ge, si ) layers show strong ferromagnetic spin fluctuations whereas layers are coupled antiferromagnetically - - both positioning the studied family close to a quantum critical point. next, localized moments attributed either to fe interstitial or antisite defects may account for magnetic impurity pair - breaking effects thus explaining the substantial variation of superconductivity among different yfe $ _ 2 $ ge $ _ 2 $ samples.
|
arxiv:1608.01130
|
missing data is a common problem faced with real - world datasets. imputation is a widely used technique to estimate the missing data. state - of - the - art imputation approaches, such as generative adversarial imputation nets ( gain ), model the distribution of observed data to approximate the missing values. such an approach usually models a single distribution for the entire dataset, which overlooks the class - specific characteristics of the data. class - specific characteristics are especially useful when there is a class imbalance. we propose a new method for imputing missing data based on its class - specific characteristics by adapting the popular conditional generative adversarial networks ( cgan ). our conditional generative adversarial imputation network ( cgain ) imputes the missing data using class - specific distributions, which can produce the best estimates for the missing values. we tested our approach on benchmark datasets and achieved superior performance compared with the state - of - the - art and popular imputation approaches.
|
arxiv:2012.00220
|
we investigate the relative intensity noise ( rin ) properties of a multi - stokes brillouin fiber ring laser. we experimentally analyse intensity noise of each stokes waves and study the noise dynamics of the cascaded brillouin scattering process. we observe up to 20 db / hz intensity noise reduction compared to that of the rin input pump laser. we examine the impact of the fiber ring quality factor on the laser rin features such as amplitude reduction and relaxation frequency. a numerical model based on a set of coupled - mode equations replicate the experimental observations ; confirming the class b like behavior of a multi - stokes brillouin laser. our study enables to determine the optimal parameter values to operate the multi - stokes laser in the low noise regime.
|
arxiv:1811.00861
|
we study hadronic polarization and the related anisotropy of the dilepton angular distribution for the reaction $ \ pi n \ to ne ^ + e ^ - $. we employ consistent effective interactions for baryon resonances up to spin - 5 / 2 to compute their contribution to the anisotropy coefficient. we show that the spin and parity of the intermediate baryon resonance is reflected in the angular dependence of the anisotropy coefficient. we present results for the anisotropy coefficient including the $ n ( 1520 ) $ and $ n ( 1440 ) $ resonances, which are essential at the collision energy of the recent data obtained by the hades collaboration on this reaction. we conclude that the anisotropy coefficient provides useful constraints for unraveling the resonance contributions to this process.
|
arxiv:1802.00062
|
nonlinear frequency conversion is ubiquitous in laser engineering and quantum information technology. a long - standing goal in photonics is to integrate on - chip semiconductor laser sources with nonlinear optical components. engineering waveguide lasers with spectra that phase - match to nonlinear processes on the same device is a formidable challenge. here, we demonstrate difference - frequency generation in an algaas bragg reflection waveguide which incorporates the gain medium for the pump laser in its core. we include quantum dot layers in the algaas waveguide that generate electrically driven laser light at ~ 790 nm, and engineer the structure to facilitate nonlinear processes at this wavelength. we perform difference - frequency generation between 1540 nm and 1630 nm using the on - chip laser, which is enabled by the broad modal phase - matching of the algaas waveguide, and measure normalized conversion efficiencies up to $ ( 0. 64 \ pm0. 21 ) $ % / w / cm $ ^ 2 $. our work demonstrates a pathway towards devices that utilize on - chip active elements and strong optical nonlinearities to enable highly integrated photonic systems - on - chip.
|
arxiv:2101.08097
|
offline reinforcement learning ( rl ) can be used to improve future performance by leveraging historical data. there exist many different algorithms for offline rl, and it is well recognized that these algorithms, and their hyperparameter settings, can lead to decision policies with substantially differing performance. this prompts the need for pipelines that allow practitioners to systematically perform algorithm - hyperparameter selection for their setting. critically, in most real - world settings, this pipeline must only involve the use of historical data. inspired by statistical model selection methods for supervised learning, we introduce a task - and method - agnostic pipeline for automatically training, comparing, selecting, and deploying the best policy when the provided dataset is limited in size. in particular, our work highlights the importance of performing multiple data splits to produce more reliable algorithm - hyperparameter selection. while this is a common approach in supervised learning, to our knowledge, this has not been discussed in detail in the offline rl setting. we show it can have substantial impacts when the dataset is small. compared to alternate approaches, our proposed pipeline outputs higher - performing deployed policies from a broad range of offline policy learning algorithms and across various simulation domains in healthcare, education, and robotics. this work contributes toward the development of a general - purpose meta - algorithm for automatic algorithm - hyperparameter selection for offline rl.
|
arxiv:2210.08642
|
semantic segmentation of rgb - d images involves understanding the appearance and spatial relationships of objects within a scene, which requires careful consideration of various factors. however, in indoor environments, the simple input of rgb and depth images often results in a relatively limited acquisition of semantic and spatial information, leading to suboptimal segmentation outcomes. to address this, we propose the multi - modal interaction and pooling attention network ( mipanet ), a novel approach designed to harness the interactive synergy between rgb and depth modalities, optimizing the utilization of complementary information. specifically, we incorporate a multi - modal interaction fusion module ( mim ) into the deepest layers of the network. this module is engineered to facilitate the fusion of rgb and depth information, allowing for mutual enhancement and correction. additionally, we introduce a pooling attention module ( pam ) at various stages of the encoder. this module serves to amplify the features extracted by the network and integrates the module ' s output into the decoder in a targeted manner, significantly improving semantic segmentation performance. our experimental results demonstrate that mipanet outperforms existing methods on two indoor scene datasets, nyudv2 and sun - rgbd, underscoring its effectiveness in enhancing rgb - d semantic segmentation.
|
arxiv:2311.11312
|
many real networks have been found to have a rich degree of symmetry, which is a very important structural property of complex network, yet has been rarely studied so far. and where does symmetry comes from has not been explained. to explore the mechanism underlying symmetry of the networks, we studied statistics of certain local symmetric motifs, such as symmetric bicliques and generalized symmetric bicliques, which contribute to local symmetry of networks. we found that symmetry of complex networks is a consequence of similar linkage pattern, which means that nodes with similar degree tend to share similar linkage targets. a improved version of ba model integrating similar linkage pattern successfully reproduces the symmetry of real networks, indicating that similar linkage pattern is the underlying ingredient that responsible for the emergence of the symmetry in complex networks.
|
arxiv:0709.1249
|
as circuit designs become more intricate, obtaining accurate performance estimation in early stages, for effective design space exploration, becomes more time - consuming. traditional logic optimization approaches often rely on proxy metrics to approximate post - mapping performance and area. however, these proxies do not always correlate well with actual post - mapping delay and area, resulting in suboptimal designs. to address this issue, we explore a ground - truth - based optimization flow that directly incorporates the exact post - mapping delay and area during optimization. while this approach improves design quality, it also significantly increases computational costs, particularly for large - scale designs. to overcome the runtime challenge, we apply machine learning models to predict post - mapping delay and area using the features extracted from aigs. our experimental results show that the model has high prediction accuracy with good generalization to unseen designs. furthermore, the ml - enhanced logic optimization flow significantly reduces runtime while maintaining comparable performance and area outcomes.
|
arxiv:2412.02268
|
we report measurements of the anisotropy of the spin echo decay for the inner layer cu site of the triple layer cuprate, hg _ 0. 8re _ 0. 2ba _ 2ca _ 2cu _ 3o _ 8 ( t _ c = 126 k ) in the pseudogap t regime below t _ pg ~ 170 k and the corresponding analysis for their interpretation. as the field alignment is varied, the shape of the decay curve changes from gaussian ( h _ 0 \ parallel c ) to single exponential ( h _ 0 \ perp c ). the latter characterizes the decay caused by the fluctuations of adjacent cu nuclear spins caused by their interactions with electron spins. the angular dependence of the second moment ( t _ { 2m } ^ { - 2 } \ equiv < \ delta \ omega ^ 2 > ) deduced from the decay curves indicates that t _ { 2m } ^ { - 2 } for h _ 0 \ parallel c, which is identical to t _ { 2g } ^ { - 2 } ( t _ { 2g } is the gaussian component ), is substantially enhanced, as seen in the pseudogap regime of the bilayer systems. comparison of t _ { 2m } ^ { - 2 } between h _ 0 \ parallel c and h _ 0 \ perp c indicates that this enhancement is caused by electron spin correlations between the inner and the outer cuo _ 2 layers. these results provide the answer to the long - standing controversy regarding the opposite t dependences of ( t _ 1t ) ^ { - 1 } and t _ { 2g } ^ { - 2 } in the pseudogap regime of bi - and trilayer systems.
|
arxiv:cond-mat/0201244
|
we explore how to enhance next - token prediction models to perform in - context imitation learning on a real robot, where the robot executes new tasks by interpreting contextual information provided during the input phase, without updating its underlying policy parameters. we propose in - context robot transformer ( icrt ), a causal transformer that performs autoregressive prediction on sensorimotor trajectories without relying on any linguistic data or reward function. this formulation enables flexible and training - free execution of new tasks at test time, achieved by prompting the model with sensorimotor trajectories of the new task composing of image observations, actions and states tuples, collected through human teleoperation. experiments with a franka emika robot demonstrate that the icrt can adapt to new tasks specified by prompts, even in environment configurations that differ from both the prompt and the training data. in a multitask environment setup, icrt significantly outperforms current state - of - the - art next - token prediction models in robotics on generalizing to unseen tasks. code, checkpoints and data are available on https : / / icrt. dev /
|
arxiv:2408.15980
|
we consider a non - local isoperimetric problem with a repulsive coulombic term. in dimension three this corresponds to the gamow ' s famous liquid drop model. we show that whenever the mass is small the ball is the unique minimizer of the problem. the proof is based on a strong version of a quantitative isoperimetric inequality.
|
arxiv:1207.0715
|
the sequential recommendation problem has attracted considerable research attention in the past few years, leading to the rise of numerous recommendation models. in this work, we explore how large language models ( llms ), which are nowadays introducing disruptive effects in many ai - based applications, can be used to build or improve sequential recommendation approaches. specifically, we design three orthogonal approaches and hybrids of those to leverage the power of llms in different ways. in addition, we investigate the potential of each approach by focusing on its comprising technical aspects and determining an array of alternative choices for each one. we conduct extensive experiments on three datasets and explore a large variety of configurations, including different language models and baseline recommendation models, to obtain a comprehensive picture of the performance of each approach. among other observations, we highlight that initializing state - of - the - art sequential recommendation models such as bert4rec or sasrec with embeddings obtained from an llm can lead to substantial performance gains in terms of accuracy. furthermore, we find that fine - tuning an llm for recommendation tasks enables it to learn not only the tasks, but also concepts of a domain to some extent. we also show that fine - tuning openai gpt leads to considerably better performance than fine - tuning google palm 2. overall, our extensive experiments indicate a huge potential value of leveraging llms in future recommendation approaches. we publicly share the code and data of our experiments to ensure reproducibility.
|
arxiv:2402.01339
|
the insulating state of matter is characterized by the excitation spectrum, but also by qualitative features of the electronic ground state. the insulating ground wavefunction in fact : ( i ) displays vanishing dc conductivity ; ( ii ) sustains macroscopic polarization ; and ( iii ) is localized. the idea that the insulating state of matter is a consequence of electron localization was first proposed in 1964 by w. kohn. i discuss here a novel definition of electron localization, rather different from kohn ' s, and deeply rooted in the modern theory of polarization. in fact the present approach links the two features ( ii ) and ( iii ) above, by means of essentially the same formalism. in the special case of an uncorrelated crystalline solid, the localization of the many - body insulating wavefunction is measured - according to our definition - by the spread of the wannier orbitals ; this spread diverges in the metallic limit. in the correlated case, the novel approach to localization is demonstrated by means of a two - band hubbard model in one dimension, undergoing a transition from band insulator to mott insulator.
|
arxiv:cond-mat/0003014
|
the in - plane thermal conductivity $ \ kappa $ of the iron selenide superconductor fese $ _ x $ ( $ t _ c $ = 8. 8 k ) were measured down to 120 mk and up to 14. 5 t ( $ \ simeq 3 / 4 h _ { c2 } $ ). in zero field, the residual linear term $ \ kappa _ 0 / t $ at $ t \ to 0 $ is only about 16 $ \ mu $ w k $ ^ { - 2 } $ cm $ ^ { - 1 } $, less than 4 % of its normal state value. such a small $ \ kappa _ 0 / t $ does not support the existence of nodes in the superconducting gap. more importantly, the field dependence of $ \ kappa _ 0 / t $ in fese $ _ x $ is very similar to that in nbse $ _ 2 $, a typical multi - gap s - wave superconductor. we consider our data as strong evidence for multi - gap nodeless superconductivity in fese $ _ x $. this kind of superconducting gap structure may be generic for all fe - based superconductors.
|
arxiv:0906.3852
|
one of the recent developments in deep learning is generalized zero - shot learning ( gzsl ), which aims to recognize objects from both seen and unseen classes, when only the labeled examples from seen classes are provided. over the past couple of years, gzsl has picked up traction and several models have been proposed to solve this problem. whereas an extensive amount of research on gzsl has been carried out in fields such as computer vision and natural language processing, no such research has been carried out to deal with time series data. gzsl is used for applications such as detecting abnormalities from ecg and eeg data and identifying unseen classes from sensor, spectrograph and other devices ' data. in this regard, we propose a latent embedding for time series - gzsl ( lets - gzsl ) model that can solve the problem of gzsl for time series classification ( tsc ). we utilize an embedding - based approach and combine it with attribute vectors to predict the final class labels. we report our results on the widely popular ucr archive datasets. our framework is able to achieve a harmonic mean value of at least 55 % on most of the datasets except when the number of unseen classes is greater than 3 or the amount of data is very low ( less than 100 training examples ).
|
arxiv:2207.12007
|
we extend and reformulate a result of solomon on the divisibility of the title. we show, for example, that if $ \ gamma $ is a finitely generated group, then $ | g | $ divides $ # \ hom ( \ gamma, g ) $ for every finite group $ g $ if and only if $ \ gamma $ has infinite abelianization. as a consequence we obtain some arithmetic properties of the number of subgroups of a given index in such a group $ \ gamma $.
|
arxiv:1105.6066
|
these lecture notes can be read in two ways. the first two sections contain a review of the phenomenology of several physical systems with slow nonequilibrium dynamics. in the conclusions we summarize the scenario derived from the solution to some solvable models ( p - spin and the like ) that are intimately connected to the mode coupling approach ( and similar ones ) to super - cooled liquids. at the end we list a number of open problems of great relevance in this context. these sections can be read independently of the body of the paper where we present some of the basic analytic techniques used to study the out of equilibrium dynamics of classical and quantum models with and without disorder. the technical part starts with a brief discussion of the role played by the environment and quenched disorder in the dynamics of classical and quantum systems. later on we expand on the dynamic functional methods and the diagrammatic expansions and resummations used to derive macroscopic equations from the microscopic dynamics. we show why the macroscopic dynamic equations for disordered models and those resulting from self - consistent approximations to non - disordered ones coincide. we review some generic properties of the slow out of equilibrium dynamics like the modifications of fdt and their link to effective temperatures, some generic scaling forms of the correlation functions, etc. finally we solve a family of mean - field glassy models. the connection between the dynamic treatment and the analysis of the free - energy landscape is also presented. we use pedagogical examples all along these lectures to illustrate the properties and results.
|
arxiv:cond-mat/0210312
|
= = = = further reading = = harrison hooker barrett and kyle j. myers, foundations of image science ( john wiley & sons, 2004 ) isbn 0471153001 ronald n. bracewell, fourier analysis and imaging ( kluwer academic, 2003 ) isbn 0306481871 roger l. easton, jr., fourier methods in imaging ( john wiley & sons, 2010 ) isbn 9780470689837 doi 10. 1002 / 9780470660102 robert d. fiete, modeling the imaging chain of digital cameras ( spie press, 2010 ) isbn 9780819483393 = = external links = = chester f. carlson center for imaging science at rit research center that offers b. s., m. s., and ph. d. degrees in imaging science. the university of arizona college of optical sciences offers an image science track for the m. s and ph. d. degree in optical sciences. science de l ' image et des medias numeriques bachelor of image science and digital media unique in canada. image sciences institute, utrecht, netherlands utrecht university institute for image sciences - focuses on fundamental and applied research in specifically medical image processing and acquisition. vanderbilt university institute of imaging science - dedicated to using imaging to improve health - care and for advancing knowledge in the biological sciences.
|
https://en.wikipedia.org/wiki/Imaging
|
we introduce stabilised property gamma, a c * - algebraic variant of property gamma which is invariant under stable isomorphism. we then show that simple separable nuclear c * - algebras with stabilised property gamma and $ \ mathrm { cu } ( a ) \ cong \ mathrm { cu } ( a \ otimes \ mathcal { z } ) $ absorb the jiang - su algebra $ \ mathcal { z } $ tensorially.
|
arxiv:2010.05792
|
the widom - rowlinson model of a fluid mixture is studied using a new cluster algorithm that is a generalization of the invaded cluster algorithm previously applied to potts models. our estimate of the critical exponents for the two - component fluid are consistent with the ising universality class in two and three dimensions. we also present results for the three - component fluid.
|
arxiv:cond-mat/9704163
|
in previous works suppes and de barros used a pure particle model to derive interference effects, where individual photons have well - defined trajectories, and hence no wave properties. in the present paper we extend that description to account for the casimir effect. we consider that the linear momentum $ \ sum \ frac { 1 } { 2 } \ hbar { \ bf k } $ of the vacuum state in quantum electrodynamics corresponds to the linear momentum of virtual photons. the casimir effect, in the cases of two parallel plates and the solid ball, is explained in terms of the pressure caused by the photons. contrary to quantum electrodynamics, we assume a finite number of virtual photons.
|
arxiv:quant-ph/9510010
|
a sample of 22 spiral galaxy rotation curves, measured in the 21 cm line of neutral hydrogen, is considered in the context of milgrom ' s modified dynamics ( mond ). combined with the previous highly selected sample of begeman et al. ( 1990 ), this comprises the current total sample of galaxies with published ( or available ) extended rotation curves and photometric observations of the light distribution. this is the observational basis of present quantitative understanding of the discrepancy between the visible mass and classical dynamical mass in galaxies. it is found that the gravitational force calculated from the observed distribution of luminous material and gas using the simple mond formula can account for the overall shape and amplitude of these 22 rotation curves, and in some cases, the predicted curve agrees with the observed rotation curve in detail. the fitted rotation curves have, in 13 cases, only one free parameter which is the mass - to - light ratio of the luminous disk ; in nine cases, there is an additional free parameter which is m / l of a central bulge or light concentration. the values of the global m / l ( bulge plus disk ) are reasonable and, when the gas mass is also included, show a scatter which is consistent with that in the tully - fisher relation. the success of the mond prescription in predicting the rotation curves in this larger, less stringently selected sample, lends further support to the idea that dynamics or gravity is non - newtonian in the limit of low accelerations and that it is unnecessary to invoke the presence of large quantities of unseen matter.
|
arxiv:astro-ph/9606089
|
high - dimensional feature vectors are likely to contain sets of measurements that are approximate replicates of one another. in complex applications, or automated data collection, these feature sets are not known a priori, and need to be determined. this work proposes a class of latent factor models on the observed high - dimensional random vector $ x \ in \ mathbb { r } ^ p $, for defining, identifying and estimating the index set of its approximately replicate components. the model class is parametrized by a $ p \ times k $ loading matrix $ a $ that contains a hidden sub - matrix whose rows can be partitioned into groups of parallel vectors. under this model class, a set of approximate replicate components of $ x $ corresponds to a set of parallel rows in $ a $ : these entries of $ x $ are, up to scale and additive error, the same linear combination of the $ k $ latent factors ; the value of $ k $ is itself unknown. the problem of finding approximate replicates in $ x $ reduces to identifying, and estimating, the location of the hidden sub - matrix within $ a $, and of the partition of its row index set $ h $. both $ h $ and its partiton can be fully characterized in terms of a new family of criteria based on the correlation matrix of $ x $, and their identifiability, as well as that of the unknown latent dimension $ k $, are obtained as consequences. the constructive nature of the identifiability arguments enables computationally efficient procedures, with consistency guarantees. when $ a $ has the errors - in - variable parametrization, the difficulty of the problem is elevated. the task becomes that of separating out groups of parallel rows that are proportional to canonical basis vectors from other dense parallel rows in $ a $. this is met under a scale assumption, via a principled way of selecting the target row indices, guided by the succesive maximization of schur complements of appropriate covariance matrices.
|
arxiv:2010.02288
|
motivated by the absence of misner string in the euclidean taub - bolt / nut solutions with flat horizons, we present a new treatment for studying the thermodynamics of these spactimes. this treatment is based on introducing a new charge, $ n = \ sigma \, n $ ( where $ n $ is the nut charge and $ \ sigma $ is some constant ) and its conjugate thermodynamic potential $ \ phi _ n $. upon identifying one of the spatial coordinates, the boundary of these solutions contains two annulus - like surfaces in addition to the constant - r surface. for these solutions, we show that these annuli surfaces receive electric, magnetic and mass / energy fluxes, therefore, they have nontrivial contributions to these conserved charges. calculating these conserved charges we find, $ q _ e = q ^ { \ infty } _ e - 2n \ phi _ m $, $ q _ m = q ^ { \ infty } _ m + 2n \ phi _ e $ and $ \ mathfrak { m } = m - 2n \ phi _ n $, where $ q ^ { \ infty } _ e $, $ q ^ { \ infty } _ m $, $ m $ are electric charge, magnetic charge and mass in the $ n = 0 $ case, while $ \ phi _ e $ and $ \ phi _ m $ are the electric and magnetic potentials. the calculated thermodynamic quantities obey the first law of thermodynamics while the entropy is the area of the horizon. furthermore, all these quantities obey smarr ' s relation. we show the consistency of these results through calculating the hamiltonian and its variation which reproduces the first law.
|
arxiv:2007.10489
|
the interplay among interaction, non - hermiticity, and disorder opens a new avenue for engineering novel phase transitions. we here study the spectral and localization features of two interacting bosons in one - dimensional nonreciprocal quasicrystals. specifically, by considering a quasiperiodic hubbard lattice with nonreciprocal hoppings, we show that the interaction can lead to a mobility edge, which arises from the fact that the bound states display a much lower threshold for spectral and extended - localized transitions than scattering states. the localization transition of bound or scattering states is accompanied by a complex - real spectrum transition. moreover, while the two - particle localized states are robust to the boundary conditions, the two - particle extended states turn into skin modes under open boundary condition. we also show the correlated dynamics to characterize these localization transitions. finally, we reveal that the bound states can form mobility edge on their own by introducing a dimerized nonreciprocal quasicrystal. our paper may pave the way for the study of non - hermitian few - body physics.
|
arxiv:2412.18755
|
we study the problem of modeling and inference for spatio - temporal count processes. our approach uses parsimonious parameterisations of multivariate autoregressive count time series models, including possible regression on covariates. we control the number of parameters by specifying spatial neighbourhood structures for possibly huge matrices that take into account spatio - temporal dependencies. this work is motivated by real data applications which call for suitable models. extensive simulation studies show that our approach yields reliable estimators.
|
arxiv:2404.02982
|
we report on high - resolution acoustic, specific - heat and thermal expansion measurements in the vicinity of the antiferromagnetic phase transition at t _ n = 1. 88 k on a high - quality single crystal of the natural mineral azurite. a detailed investigation of the critical contribution to the various quantities at t _ n is presented. the set of critical exponents and amplitude ratios of the singular contributions above and below the transition indicate that the system can be reasonably well described by a three - dimensional heisenberg antiferromagnet.
|
arxiv:1206.0661
|
in this paper, we generalize the almgren - chriss ' s market impact model to a more realistic and flexible framework and employ it to derive and analyze some aspects of optimal liquidation problem in a security market. we illustrate how a trader ' s liquidation strategy alters when multiple venues and extra information are brought into the security market and detected by the trader. this study gives some new insights into the relationship between liquidation strategy and market liquidity, and provides a multi - scale approach to the optimal liquidation problem with randomly varying volatility.
|
arxiv:1607.04553
|
the properties of spin polarized neutron matter are studied both at zero and finite temperature using the d1 and the d1p parameterizations of the gogny interaction. the results show two different behaviors : whereas the d1p force exhibits a ferromagnetic transition at a density of $ \ rho _ c \ sim 1. 31 $ fm $ ^ { - 3 } $ whose onset increases with temperature, no sign of such a transition is found for d1 at any density and temperature, in agreement with recent microscopic calculations.
|
arxiv:nucl-th/0604058
|
uncertainty about models and data is ubiquitous in the computational social sciences, and it creates a need for robust social network algorithms, which can simultaneously provide guarantees across a spectrum of models and parameter settings. we begin an investigation into this broad domain by studying robust algorithms for the influence maximization problem, in which the goal is to identify a set of k nodes in a social network whose joint influence on the network is maximized. we define a robust influence maximization framework wherein an algorithm is presented with a set of influence functions, typically derived from different influence models or different parameter settings for the same model. the different parameter settings could be derived from observed cascades on different topics, under different conditions, or at different times. the algorithm ' s goal is to identify a set of k nodes who are simultaneously influential for all influence functions, compared to the ( function - specific ) optimum solutions. we show strong approximation hardness results for this problem unless the algorithm gets to select at least a logarithmic factor more seeds than the optimum solution. however, when enough extra seeds may be selected, we show that techniques of krause et al. can be used to approximate the optimum robust influence to within a factor of 1 - 1 / e. we evaluate this bicriteria approximation algorithm against natural heuristics on several real - world data sets. our experiments indicate that the worst - case hardness does not necessarily translate into bad performance on real - world data sets ; all algorithms perform fairly well.
|
arxiv:1602.05240
|
we study the breaking of gauge symmetry for higher spin theory on ads _ 4 dual to the 3d critical o ( n ) vector model. it was argued that the breaking is due to the change of boundary condition for a scalar field through a loop effect and the goldstone modes are bound states of a scalar field and higher spin field. the masses of higher spin fields were obtained from the anomalous dimensions of dual currents at the leading order in 1 / n, and we reproduce them from the o ( n ) vector model in the conformal perturbation theory. the anomalous dimensions can be computed from the bulk theory using witten diagrams, and we show that the bulk computation reduces to the boundary one in the conformal perturbation theory. with this fact our computation provides an additional support for the bulk interpretation.
|
arxiv:1601.01784
|
we study the domain structure in ferroelectric thin films with a ` passive ' layer ( material with damaged ferroelectric properties ) at the interface between the film and electrodes within a continuous medium approximation. an abrupt transition from a monodomain to a polydomain state has been found with the increase of the ` passive ' layer thickness $ d $. the domain width changes very quickly at the transition ( exponentially with $ d ^ { - 2 } $ ). we have estimated the dielectric response $ dp / de $ ( the slope of the hysteresis loop ) in the ` fatigued ' multidomain state and found that it is in agreement with experiment, assuming realistic parameters of the layer. we derive a simple universal relation for the dielectric response, which scales as $ 1 / d $, involving only the properties of the passive layer. this relation qualitatively reproduces the evolution of the hysteresis loop in fatigued samples and it could be tested with controlled experiments. it is expected that the coercive field should increase with decreasing lateral size of the film. we believe that specific properties of the domain structure under bias voltage in ferroelectrics with a passive layer can resolve the long - standing ` paradox of the coercive field '.
|
arxiv:cond-mat/9908181
|
we study the emission of gravitons by a homogeneous brane with the gauss - bonnet term into an anti de sitter five dimensional bulk spacetime. it is found that the graviton emission depends on the curvature scale and the gauss - bonnnet coupling and that the amount of emission generally decreases. therefore nucleosynthesis constraints are easier to satisfy by including the gauss - bonnet term.
|
arxiv:hep-th/0701257
|
the closest string problem is an np - complete problem which appears more commonly in bioinformatics and coding theory. less surprisingly, classical approaches have been pursued with two prominent algorithms being the genetic algorithm and simulated annealing. latest improvements to quantum computing devices with a specialization in optimization tasks such as dwave systems, suggest that an attempt to embed the problem in a model accepted by such systems is worthwhile. in this work, two qubo formulations have been proposed, with one being a slight modification over the other. subsequently, an evaluation based on a few simple test cases had been carried out on both formulations. in this regard, the d - wave annealers have been used, while providing guidelines for optimality on certain platform - specific concerns. for evaluation purposes, a metric termed occurrence ratio ( or ) has been defined. with minimal hyperparameter tuning, the expected solutions were obtained for every test case and the optimality was guaranteed. to address practical and implementation issues, an inherent decomposition strategy based on the possibility of having substrings has been elucidated to accommodate the restricted qubit count. conclusively, the need for further investigation on tuning the hyperparameters is emphasized.
|
arxiv:2310.12852
|
the holonomic rank of the a - hypergeometric system h _ a ( \ beta ) is shown to depend on the parameter vector \ beta when the underlying toric ideal i _ a is a non cohen macaulay codimension 2 toric ideal. the set of exceptional parameters is usually infinite.
|
arxiv:math/0009148
|
it is commonly believed that the earliest stages of star - formation in the universe were self - regulated by global radiation backgrounds - either by the ultraviolet lyman - werner ( lw ) photons emitted by the first stars ( directly photodissociating h _ 2 ), or by the x - rays produced by accretion onto the black hole ( bh ) remnants of these stars ( heating the gas but catalyzing h _ 2 formation ). recent studies have suggested that a significant fraction of the first stars may have had low masses ( a few m _ sun ). such stars do not leave bh remnants and they have softer spectra, with copious infrared ( ir ) radiation at photon energies around 1ev. similar to lw and x - ray photons, these photons have a mean - free path comparable to the hubble distance, building up an early ir background. here we show that if soft - spectrum stars, with masses of a few m _ sun, contributed more than 1 % of the uv background ( or their mass fraction exceeded 90 % ), then their ir radiation dominated radiative feedback in the early universe. the feedback is different from the uv feedback from high - mass stars, and occurs through the photo - detachment of h ^ - ions, necessary for efficient h _ 2 formation. nevertheless, we find that the baryon fraction which must be incorporated into low - mass stars in order to suppress h _ 2 - cooling is only a factor of few higher than for high - mass stars.
|
arxiv:1206.1861
|
we propose a new approach for constructing a 3d representation from a 2d wireframe drawing. a drawing is simply a parallel projection of a 3d object onto a 2d surface ; humans are able to recreate mental 3d models from 2d representations very easily, yet the process is very difficult to emulate computationally. we hypothesize that our ability to perform this construction relies on the angles in the 2d scene, among other geometric properties. being able to reproduce this reconstruction process automatically would allow for efficient and robust 3d sketch interfaces. our research focuses on the relationship between 2d geometry observable in the sketch and 3d geometry derived from a potential 3d construction. we present a fully automated system that constructs 3d representations from 2d wireframes using a neural network in conjunction with a genetic search algorithm.
|
arxiv:1007.2442
|
we study a class of triangulated categories obtained as verdier quotients of 3 - calabi - yau categories combinatorially described by quivers with potential from ( decorated ) marked surfaces. we study their bounded t - structures and consider in particular the exchange graphs of hearts and silting objects, and show that the koszul isomorphism between these graphs is preserved under verdier quotient.
|
arxiv:2411.00207
|
in the present paper, we combine numerical and experimental approaches to study the dynamics of stable and unstable internal wave attractors. the problem is considered in a classic trapezoidal setup filled with a uniformly stratified fluid. energy is injected into the system at global scale by the small - amplitude motion of a vertical wall. wave motion in the test tank is measured with the help of conventional synthetic schlieren and piv techniques. the numerical setup closely reproduces the experimental one in terms of geometry and the operational range of the reynolds and schmidt numbers. the spectral element method is used as a numerical tool to simulate the nonlinear dynamics of a viscous salt - stratified fluid. we show that the results of three - dimensional calculations are in excellent qualitative and quantitative agreement with the experimental data, including the spatial and temporal parameters of the secondary waves produced by triadic resonance instability. further, we explore experimentally and numerically the effect of lateral walls on secondary currents and spanwise distribution of velocity amplitudes in the wave beams. finally, we test the assumption of a bidimensional flow and estimate the error made in synthetic schlieren measurements due to this assumption.
|
arxiv:1602.07186
|
this paper describes latest results on lepton ( electron, muon and tau ) and photon particle identification at the atlas and cms experiments, with emphasis on how the particle identification can be validated and its performance determined using early lhc data.
|
arxiv:0808.3920
|
we study the asymptotic dynamics of 3d gravity with rindler boundary conditions both in flat and ads spacetimes. we do this by using the angular quantization and hamiltonian reduction of the action to the wess - zumino - witten theory on the boundary. we then rewrite the boundary action as a functional of elements of the asymptotic symmetry group.
|
arxiv:2406.05386
|
detecting protein - protein interactions ( ppis ) is crucial for understanding genetic mechanisms, disease pathogenesis, and drug design. however, with the fast - paced growth of biomedical literature, there is a growing need for automated and accurate extraction of ppis to facilitate scientific knowledge discovery. pre - trained language models, such as generative pre - trained transformers ( gpt ) and bidirectional encoder representations from transformers ( bert ), have shown promising results in natural language processing ( nlp ) tasks. we evaluated the performance of ppi identification of multiple gpt and bert models using three manually curated gold - standard corpora : learning language in logic ( lll ) with 164 ppis in 77 sentences, human protein reference database with 163 ppis in 145 sentences, and interaction extraction performance assessment with 335 ppis in 486 sentences. bert - based models achieved the best overall performance, with biobert achieving the highest recall ( 91. 95 % ) and f1 - score ( 86. 84 % ) and pubmedbert achieving the highest precision ( 85. 25 % ). interestingly, despite not being explicitly trained for biomedical texts, gpt - 4 achieved commendable performance, comparable to the top - performing bert models. it achieved a precision of 88. 37 %, a recall of 85. 14 %, and an f1 - score of 86. 49 % on the lll dataset. these results suggest that gpt models can effectively detect ppis from text data, offering promising avenues for application in biomedical literature mining. further research could explore how these models might be fine - tuned for even more specialized tasks within the biomedical domain.
|
arxiv:2303.17728
|
the notion of free link is a generalized notion of virtual link. in the present paper we define the group of free braids, prove the alexander theorem that all free links can be obtained as closures of free braids and prove a markov theorem, which gives necessary and sufficient conditions for two free braids to have the same free link closure. our result is expected to be useful in study the topology invariants for free knots and links.
|
arxiv:1112.4061
|
we study the quasinormal modes of $ p $ - form fields in spherical black holes in $ d $ - dimensions. using the spherical symmetry of the black holes and gauge symmetry, we show the $ p $ - form field can be expressed in terms of the coexact $ p $ - form and the coexact $ ( p - 1 ) $ - form on the sphere $ s ^ { d - 2 } $. these variables allow us to find the master equations. by utilizing the s - deformation method, we explicitly show the stability of $ p $ - form fields in the spherical black hole spacetime. moreover, using the wkb approximation, we calculate the quasinormal modes of the $ p $ - form fields in $ d ( \ leq10 ) $ - dimensions.
|
arxiv:1901.07723
|
we introduce two types of estimators of the finite - dimensional parameters in the case of observations of inhomogeneous poisson processes. these are the estimators of the method of moments and multi - step mle. it is shown that the estimators of the method of moments are consistent and asymptotically normal and the multi - step mle are consistent and asymptotically efficient. the construction of multi - step mle - process is done in two steps. first we construct a consistent estimator by the observations on some learning interval and then this estimator is used for construction of one - step and two - step mles. the main advantage of the proposed approach is its computational simplicity.
|
arxiv:1806.06378
|
aims : we consider cold self - similar magnetohydrodynamic ( mhd ) disc wind solutions to describe jets that are launched from the circumcompanion accretion discs in post - agb binaries. resulting predictions are matched to observations for five different post - agb binaries. this both tests the physical validity of the mhd disc wind paradigm and reveals the accretion disc properties. results : many of the time - series ' properties are reproduced well by the models, though systematic mismatches, such as overestimated rotation, remain. four targets imply accretion discs that reach close to the secondary ' s stellar surface, while one is fitted with an unrealistically large inner radius of about 20 stellar radii. some fits imply inner disc temperatures over 10 000 k, seemingly discrepant with a previous observational estimate from h band interferometry. this estimate is, however, shown to be biased. fitted mass - accretion rates range from about 10 ^ - 6 to 10 ^ - 3 solar masses per year. relative to the jets launched from young stellar objects ( ysos ), all targets prefer winds with higher ejection efficiencies, lower magnetizations and thicker discs. conclusions : our models show that current cold mhd disc wind solutions can explain many of the jet - related balmer alpha features seen in post - agb binaries, though systematic discrepancies remain. this includes, but is not limited to, overestimated rotation and underestimated post - agb circumbinary disc lifetimes. the consideration of thicker discs and the inclusion of irradiation from the post - agb primary, leading to warm magnetothermal wind launching, might alleviate these.
|
arxiv:2406.09280
|
a / b testing is a widely - used paradigm within marketing optimization because it promises identification of causal effects and because it is implemented out of the box in most messaging delivery software platforms. modern businesses, however, often run many a / b / n tests at the same time and in parallel, and package many content variations into the same messages, not all of which are part of an explicit test. whether as the result of many teams testing at the same time, or as part of a more sophisticated reinforcement learning ( rl ) approach that continuously adapts tests and test condition assignment based on previous results, dynamic parallel testing cannot be evaluated the same way traditional a / b tests are evaluated. this paper presents a method for disentangling the causal effects of the various tests under conditions of continuous test adaptation, using a matched - synthetic control group that adapts alongside the tests.
|
arxiv:2305.01334
|
we investigate general elliptic boundary - value problems in h \ " ormander inner product spaces that form the extended sobolev scale. the latter consists of all hilbert spaces that are interpolation spaces with respect to the sobolev hilbert scale. we prove that the operator corresponding to an arbitrary elliptic problem is fredholm in appropriate couples of the h \ " ormander spaces and induces a collection of isomorphisms on the extended sobolev scale. we obtain a local a priory estimate for generalized solutions to this problem and prove a theorem on their local regularity in the h \ " ormander spaces. we find new sufficient conditions under which generalized derivatives ( of a given order ) of the solutions are continuous.
|
arxiv:1612.04220
|
finite groups in which every element has prime power order ( eppo - groups ) are nowadays fairly well understood. for instance, if $ g $ is a soluble eppo - group, then the fitting height of $ g $ is at most 3 and $ | \ pi ( g ) | \ leqslant 2 $ ( higman, 1957 ). moreover, suzuki showed that if $ g $ is insoluble, then the soluble radical of $ g $ is a 2 - group and there are exactly eight nonabelian simple eppo - groups. in the present work we concentrate on finite groups in which every commutator has prime power order ( cppo - groups ). roughly, we show that if $ g $ is a cppo - group, then the structure of $ g ' $ is similar to that of an eppo - group. in particular, we show that the fitting height of a soluble cppo - group is at most 3 and $ | \ pi ( g ' ) | \ leqslant 3 $. moreover, if $ g $ is insoluble, then $ r ( g ' ) $ is a 2 - group and $ g ' / r ( g ' ) $ is isomorphic to a simple eppo - group.
|
arxiv:2312.11263
|
working in doubling metric spaces, we examine the connections between different dimensions, whitney covers, and geometrical properties of tubular neighborhoods. in the euclidean space, we relate these concepts to the behavior of the surface area of the boundaries of parallel sets. in particular, we give characterizations for the minkowski and the spherical dimensions by means of the whitney ball count.
|
arxiv:1209.0629
|
we use high resolution cosmological hydrodynamical simulations to demonstrate that cold flow gas accretion, particularly along filaments, modifies the standard picture of gas accretion and cooling onto galaxy disks. in the standard picture, all gas is initially heated to the virial temperature of the galaxy as it enters the virial radius. low mass galaxies are instead dominated by accretion of gas that stays well below the virial temperature, and even when a hot halo is able to develop in more massive galaxies there exist dense filaments that penetrate inside of the virial radius and deliver cold gas to the central galaxy. for galaxies up to ~ l *, this cold accretion gas is responsible for the star formation in the disk at all times to the present. even for galaxies at higher masses, cold flows dominate the growth of the disk at early times. within this modified picture, galaxies are able to accrete a large mass of cold gas, with lower initial gas temperatures leading to shorter cooling times to reach the disk. although star formation in the disk is mitigated by supernovae feedback, the short cooling times allow for the growth of stellar disks at higher redshifts than predicted by the standard model.
|
arxiv:0812.0007
|
we reveal the rule with which we predicted, and verified by detailed numerical calculations on dozens of specific cases over the last decade, the emergence of hidden induced states and the formation of quartets of order parameters. the rule stipulates that if n order parameters are such that their cyclic products equal + 1 or - 1 then the presence of any n - 1 of them will necessarily induce the missing order parameter as a hidden order. we demonstrate that the rule results from general microscopic mean field theory and is thus universally valid. of exceptional physical interest are the cases n = 4 called quartets, and all n > 4 cases decompose into overlaping quartets which are the building blocks of observable patterns of condensates. quartets may be found in two regimes, the " hierarchy " regime and the " equity " regime, and transitions between the two regimes exhibit universal characteristics. following the rule, we predict many characteristic examples of quartets involving all types of particle - hole and superconducting condensates.
|
arxiv:1305.2976
|
in this paper, we propose a class of graphs $ g ^ { \ star } ( m, t ) $ and first study some structural properties, such as, average degree, on them. the results show that ( 1 ) graphs $ g ^ { \ star } ( m, t ) $ have density feature because of their average degrees proportional to time step $ t $ not to a constant in the large graph size limit, ( 2 ) graphs $ g ^ { \ star } ( m, t ) $ obey the power - law distribution with exponent equal to $ 2 $, which is rarely found in most previous scale - free models, ( 3 ) graphs $ g ^ { \ star } ( m, t ) $ display small - world property in terms of ultra - small diameter and higher clustering coefficient, and ( 4 ) graphs $ g ^ { \ star } ( m, t ) $ possess disassortative structure with respect to pearson correlation coefficient smaller than zero. in addition, we consider the trapping problem on the proposed graphs $ g ^ { \ star } ( m, t ) $ and then find that they all have more optimal trapping efficiency by means of their own average trapping time achieving the theoretical lower bound, a phenomenon that is seldom observed in existing scale - free models. we conduct extensive simulations that are consistent with our theoretical analysis.
|
arxiv:2003.12392
|
environmental sound classification ( esc ) is a challenging problem due to the unstructured spatial - temporal relations that exist in the sound signals. recently, many studies have focused on abstracting features from convolutional neural networks while the learning of semantically relevant frames of sound signals has been overlooked. to this end, we present an end - to - end framework, namely feature pyramid attention network ( fpam ), focusing on abstracting the semantically relevant features for esc. we first extract the feature maps of the preprocessed spectrogram of the sound waveform by a backbone network. then, to build multi - scale hierarchical features of sound spectrograms, we construct a feature pyramid representation of the sound spectrograms by aggregating the feature maps from multi - scale layers, where the temporal frames and spatial locations of semantically relevant frames are localized by fpam. specifically, the multiple features are first processed by a dimension alignment module. afterward, the pyramid spatial attention module ( psa ) is attached to localize the important frequency regions spatially with a spatial attention module ( sam ). last, the processed feature maps are refined by a pyramid channel attention ( pca ) to localize the important temporal frames. to justify the effectiveness of the proposed fpam, visualization of attention maps on the spectrograms has been presented. the visualization results show that fpam can focus more on the semantic relevant regions while neglecting the noises. the effectiveness of the proposed methods is validated on two widely used esc datasets : the esc - 50 and esc - 10 datasets. the experimental results show that the fpam yields comparable performance to state - of - the - art methods. a substantial performance increase has been achieved by fpam compared with the baseline methods.
|
arxiv:2205.14411
|
if g is a finite group, some aspects of the modular representation theory depend on the cochains c ^ * ( bg ; k ), viewed as a commutative ring spectrum. we consider here its singularity category ( in the sense of the author and stevenson arxiv 1702. 07957 ) and show that if c ^ * ( bg ; k ) is a homotopical complete intersection in a strong sense, then the singularity category is the bounded derived category of the k - nullification of the connective ring spectrum c _ * ( \ omega bg _ p ). in the course of this we establish a form of gorenstein duality for c _ * ( \ omega bg _ p ) for these groups.
|
arxiv:2504.03050
|
we extend the mechanism for noise - induced phase transitions proposed by ibanes et al. [ phys. rev. lett. 87, 020601 - 1 ( 2001 ) ] to pattern formation phenomena. in contrast with known mechanisms for pure noise - induced pattern formation, this mechanism is not driven by a short - time instability amplified by collective effects. the phenomenon is analyzed by means of a modulated mean field approximation and numerical simulations.
|
arxiv:cond-mat/0211181
|
we present a bayesian framework to establish a power - spectrum space decomposition of frequency tomographic ( psdft ) data for future intensity mapping ( im ) experiments. different from most traditional component - separation methods which work in the map domain, this new technique treats multifrequency power spectra as raw data and can reconstruct component power spectra by taking advantage of distinct components ' correlation patterns in the frequency domain. we have validated this new technique for both interferometric and single - dish - like im experiments, respectively, using synthesized mock data that contain bright foreground contaminants, im signals, and instrumental effects at different frequencies. the psdft approach can effectively remove the bright foreground contamination and extract the targeted im signals using a bayesian approach in a power - spectrum subspace. this new approach can be directly applied to a broad range of im analyses and will be well suited to future high - quality im datasets, providing a powerful tool for future im surveys.
|
arxiv:2308.14777
|
the gravitational instability of a fully ionized gas is analyzed within the framework of linear irreversible thermodynamics. in particular, the presence of a heat flux corresponding to generalized thermodynamic forces is shown to affect the properties of the dispersion relation governing the stability of this kind of system in certain problems of interest.
|
arxiv:0705.4121
|
programming efficiently heterogeneous systems is a major challenge, due to the complexity of their architectures. intel oneapi, a new and powerful standards - based unified programming model, built on top of sycl, addresses these issues. in this paper, oneapi is provided with co - execution strategies to run the same kernel between different devices, enabling the exploitation of static and dynamic policies. on top of that, static and dynamic load - balancing algorithms are integrated and analyzed. this work evaluates the performance and energy efficiency for a well - known set of regular and irregular hpc benchmarks, using an integrated gpu and cpu. experimental results show that co - execution is worthwhile when using dynamic algorithms, improving efficiency even more when using unified shared memory.
|
arxiv:2106.01726
|
recent work of m. d. johnston et al. has produced sufficient conditions on the structure of a chemical reaction network which guarantee that the corresponding discrete state space system exhibits an extinction event. the conditions consist of a series of systems of equalities and inequalities on the edges of a modified reaction network called a domination - expanded reaction network. in this paper, we present a computational implementation of these conditions written in python and apply the program on examples drawn from the biochemical literature, including a model of polyamine metabolism in mammals and a model of the pentose phosphate pathway in trypanosoma brucei. we also run the program on 458 models from the european bioinformatics institute ' s biomodels database and report our results.
|
arxiv:1701.02014
|
recently it has been shown that the fidelity of the ground state of a quantum many - body system can be used to detect its quantum critical points ( qcps ). if g denotes the parameter in the hamiltonian with respect to which the fidelity is computed, we find that for one - dimensional models with large but finite size, the fidelity susceptibility \ chi _ f can detect a qcp provided that the correlation length exponent satisfies \ nu < 2. we then show that \ chi _ f can be used to locate a qcp even if \ nu \ ge 2 if we introduce boundary conditions labeled by a twist angle n \ theta, where n is the system size. if the qcp lies at g = 0, we find that if n is kept constant, \ chi _ f has a scaling form given by \ chi _ f \ sim \ theta ^ { - 2 / \ nu } f ( g / \ theta ^ { 1 / \ nu } ) if \ theta \ ll 2 \ pi / n. we illustrate this both in a tight - binding model of fermions with a spatially varying chemical potential with amplitude h and period 2q in which \ nu = q, and in a xy spin - 1 / 2 chain in which \ nu = 2. finally we show that when q is very large, the model has two additional qcps at h = \ pm 2 which cannot be detected by studying the energy spectrum but are clearly detected by \ chi _ f. the peak value and width of \ chi _ f seem to scale as non - trivial powers of q at these qcps. we argue that these qcps mark a transition between extended and localized states at the fermi energy.
|
arxiv:1210.1382
|
in this paper, we propose a novel equilibrium solution notion for the time - inconsistent stochastic linear - quadratic optimal control problem. this notion is called the mixed equilibrium solution, which consists of two parts : a pure - feedback - strategy part and an open - loop - control part. when the pure - feedback - strategy part is zero or the open - loop - control part does not depend on the initial state, the mixed equilibrium solution reduces to the open - loop equilibrium control and the feedback equilibrium strategy, respectively. using a maximum - principle - like methodology with forward - backward stochastic difference equations, a necessary and sufficient condition is established to characterize the existence of a mixed equilibrium solution. then, by decoupling the forward - backward stochastic difference equations, three sets of difference equations, which together portray the existence of a mixed equilibrium solution, are obtained. moreover, the case with a fixed time - state initial pair and the case with all the initial pairs are separately investigated. furthermore, an example is constructed to show that the mixed equilibrium solution exists for all the initial pairs, although neither the open - loop equilibrium control nor the feedback equilibrium strategy exists for some initial pairs.
|
arxiv:1802.03032
|
interstellar molecular clouds are gamma ray sources through the interactions with cosmic ray protons followed by production of neutral pions which decay into gamma rays. we present new nanten2 observations of the tev gamma ray snr rxj1713. 7 - 3946 and the w28 region in the 12co j = 2 - 1, 4 - 3 and 7 - 6 emission lines. in rxj1713. 7 - 3946 we confirm that the local molecular gas having velocities around - 10 km / s shows remarkably good spatial correlations with the snr. we show that the x ray peaks are well correlated with the molecular gas over the whole snr and suggest that the interactions between the snr and the molecular gas play an important role in cosmic ray acceleration via several ways including magnetic field compression. the co j = 4 - 3 distribution towards peak c shows a compact and dense cloud core having a size of about 1 pc as well as a broad wing. the core shows a notable anti - correlation with the suzaku x ray image and is also associated with hard gamma rays as observed with hess. based on these findings, we present a picture that peak c is a molecular clump survived against the impact of the sn blast waves and is surrounded by high energy electrons emitting the x ray. the tev gamma ray distribution is, on the other hand, more extended into the molecular gas, supporting the hadronic origin of gamma ray production. w28 is one of the most outstanding star forming regions exhibiting tev gamma rays as identified through a comparison between the nanten co dataset and hess gamma ray sources. in the w28 region, we show the co j = 2 - 1 distribution over the whole region as well as the detailed image of the two tev gamma ray peaks. one of them show strong co j = 7 - 6 emission, suggesting high excitation conditions in this high mass star forming core. a pursuit for the detailed mechanism to produce gamma rays is in progress.
|
arxiv:0810.5416
|
in this work we derive the modifications to the boltzmann equation governing the cosmic evolution of relic abundances induced by dilaton dissipative - source and non - critical - string terms in dilaton - driven non - equilibrium string cosmologies. we also discuss briefly the most important phenomenological consequences, including modifications of the constraints on the available parameter space of cosmologically appealing particle physics models, imposed by recent precision data of astrophysical measurements.
|
arxiv:hep-ph/0608153
|
the quantum phase diagram of disordered electron systems as function of the concentration of magnetic impurities nm and the local exchange coupling j is studied in the dilute limit. we take into account the anderson localisation of the electrons by a nonperturbative numerical treatment of the disorder potential. the competition between rkky interaction jrkky and the kondo effect, as governed by the temperature scale tk, is known to gives rise to a rich magnetic quantum phase diagram, the doniach diagram. our numerical calculations show that in a disordered system both the kondo temperature tk and jrkky are widely distributed. accordingly, also their ratio, jrkky / tk is widely distributed as shown in fig. 1 ( a ). however, we find a sharp cutoff of that distribution, which allows us to define a critical density of magnetic impurities nc below which kondo screening wins at all sites of the system above a critical coupling jc, forming the kondo phase [ see fig. 1 ( b ) ]. as disorder is increased, jc increases and a spin coupled phase is found to grow at the expense of the kondo phase. from these distribution functions we derive the magnetic susceptibility which show anomalous power law behavior. in the kondo phase that power is determined by the wide distribution of the kondo temperature, while in the spin coupled phase it is governed by the distribution of jrkky. at low densities and small j < jc we identify a paramagnetic phase. we also report results on a honeycomb lattice, graphene, where we find that the spin coupled phase is more stable against kondo screening, but is more easily destroyed by disorder into a pm phase.
|
arxiv:1211.1734
|
the bispectrum, the three - point function of density fluctuations in fourier space, is the lowest order statistic that carries information about the spatial coherence of large - scale structures. for gaussian initial conditions, when the density fluctuation amplitude is small, tree - level ( leading order ) perturbation theory predicts a characteristic dependence of the bispectrum on the shape of the triangle formed by the three wave vectors. this configuration dependence provides a signature of gravitational instability, and departures from it in galaxy catalogs can be interpreted as due to bias, that is, non - gravitational effects. on the other hand, n - body simulations indicate that the reduced three - point function becomes relatively shape - independent in the strongly non - linear regime. in order to understand this non - linear transition and assess the domain of reliability of shape - dependence as a probe of bias, we calculate the one - loop ( next - to - leading order ) corrections to the bispectrum in perturbation theory. we compare these results with measurements in numerical simulations with scale - free and cdm initial power spectra. we find that the one - loop corrections account very well for the departures from the tree - level results measured in numerical simulations on weakly non - linear scales. in this regime, the reduced bispectrum qualitatively retains its tree - level shape, but the amplitude can change significantly. at smaller scales, the reduced bispectrum in the simulations starts to flatten, an effect which can be partially understood from the one - loop results. in the strong clustering regime, where perturbation theory breaks down entirely, the simulation results confirm that the reduced bispectrum has almost no dependence on triangle shape, in rough agreement with the hierarchical ansatz.
|
arxiv:astro-ph/9704075
|
electromagnetic calorimeters used in high - energy physics and astrophysics rely heavily on high - z inorganic scintillators, such as lead tungstate ( pbwo4 or pwo ). the crystalline structure and lattice orientation of inorganic scintillators are frequently underestimated in detector design, even though it is known that the crystalline lattice strongly modifies the features of the electromagnetic processes inside the crystal. a novel method has been developed for precisely bonding pwo crystals with aligned atomic planes within 100 { \ mu } rad, exploiting x - ray diffraction ( xrd ) to accurately measure miscut angles. this method demonstrates the possibility to align a layer of crystals along the same crystallographic direction, opening a new technological path towards the development of next - generation electromagnetic calorimeters.
|
arxiv:2503.17053
|
for the lisa and taiji missions, both transient and continuous data anomalies would pose significant challenges to the detection, estimation, and subsequent scientific interpretation of gravitational wave signals. as is indicated by the experiences of lisa pathfinder and taiji - 1, these anomalies may originate from the disturbances of the gravitational reference sensors due to routine maintenances and unexpected environmental or instrumental issues. to effectively mitigate such anomalies and thereby enhance the robustness and reliability of the scientific outputs, we suggest to employ the ` ` position noise suppressing ' ' time delay interferometry channels. through analytical derivations and numerical simulations, we demonstrate that these time delay interferometry channels can suppress data anomalies by more than 2 orders of magnitude within the sensitive band of 0. 1 mhz - 0. 05 hz, while still remaining sensitive to most of the target signals. compared with existing researches that focus on reconstructing and subtracting data anomalies, our method does not rely on the prior knowledge about the models of anomalies. furthermore, the potential application scenarios of these channels have also been explored.
|
arxiv:2206.10664
|
the distribution engendered by successive splitting of one point vortex are considered. the process of splitting a vortex in three using a reverse three - point vortex collapse course is analysed in great details and shown to be dissipative. a simple process of successive splitting is then defined and the resulting vorticity distribution and vortex populations are analysed.
|
arxiv:1010.0594
|
we study wilf ' s conjecture for numerical semigroups $ s $ such that the second least generator $ a _ 2 $ of $ s $ satisfies $ a _ 2 > \ frac { c ( s ) + \ mu ( s ) } { 3 } $, where $ c ( s ) $ is the conductor and $ \ mu ( s ) $ the multiplicity of $ s $. in particular, we show that for these semigroups wilf ' s conjecture holds when the multiplicity is bounded by a quadratic function of the embedding dimension.
|
arxiv:1710.09245
|
the very - high - energy ( vhe ; e > 100 gev ) gamma - ray emission observed from a number of supernova remnants ( snrs ) indicates particle acceleration to high energies at the shock of the remnants and a potentially significant contribution to galactic cosmic rays. it is extremely difficult to determine whether protons ( through hadronic interactions and subsequent pion decay ) or electrons ( through inverse compton scattering on ambient photon fields ) are responsible for this emission. for a successful diagnostic, a good understanding of the spatial and energy distribution of the underlying particle population is crucial. most snrs are created in core - collapse explosions and expand into the wind bubble of their progenitor stars. this circumstellar medium features a complex spatial distribution of gas and magnetic field which naturally strongly affects the resulting particle population. in this work, we conduct a detailed study of the spectro - spatial evolution of the electrons accelerated at the forward shock of core - collapse snrs and their non - thermal radiation, using the ratpac code that is designed for the time - and spatially dependent treatment of particle acceleration at snr shocks. we focus on the impact of the spatially inhomogeneous magnetic field through the efficiency of diffusion and synchrotron cooling. it is demonstrated that the structure of the circumstellar magnetic field can leave strong signatures in the spectrum and morphology of the resulting non - thermal emission.
|
arxiv:2111.06946
|
just as computational simulations of atoms, molecules and cells have shaped the way we study the sciences, true - to - life simulations of human - like agents can be valuable tools for studying human behavior. we propose humanoid agents, a system that guides generative agents to behave more like humans by introducing three elements of system 1 processing : basic needs ( e. g. hunger, health and energy ), emotion and closeness in relationships. humanoid agents are able to use these dynamic elements to adapt their daily activities and conversations with other agents, as supported with empirical experiments. our system is designed to be extensible to various settings, three of which we demonstrate, as well as to other elements influencing human behavior ( e. g. empathy, moral values and cultural background ). our platform also includes a unity webgl game interface for visualization and an interactive analytics dashboard to show agent statuses over time. our platform is available on https : / / www. humanoidagents. com / and code is on https : / / github. com / humanoidagents / humanoidagents
|
arxiv:2310.05418
|
the classic problems of testing uniformity of and learning a discrete distribution, given access to independent samples from it, are examined under general $ \ ell _ p $ metrics. the intuitions and results often contrast with the classic $ \ ell _ 1 $ case. for $ p > 1 $, we can learn and test with a number of samples that is independent of the support size of the distribution : with an $ \ ell _ p $ tolerance $ \ epsilon $, $ o ( \ max \ { \ sqrt { 1 / \ epsilon ^ q }, 1 / \ epsilon ^ 2 \ } ) $ samples suffice for testing uniformity and $ o ( \ max \ { 1 / \ epsilon ^ q, 1 / \ epsilon ^ 2 \ } ) $ samples suffice for learning, where $ q = p / ( p - 1 ) $ is the conjugate of $ p $. as this parallels the intuition that $ o ( \ sqrt { n } ) $ and $ o ( n ) $ samples suffice for the $ \ ell _ 1 $ case, it seems that $ 1 / \ epsilon ^ q $ acts as an upper bound on the " apparent " support size. for some $ \ ell _ p $ metrics, uniformity testing becomes easier over larger supports : a 6 - sided die requires fewer trials to test for fairness than a 2 - sided coin, and a card - shuffler requires fewer trials than the die. in fact, this inverse dependence on support size holds if and only if $ p > \ frac { 4 } { 3 } $. the uniformity testing algorithm simply thresholds the number of " collisions " or " coincidences " and has an optimal sample complexity up to constant factors for all $ 1 \ leq p \ leq 2 $. another algorithm gives order - optimal sample complexity for $ \ ell _ { \ infty } $ uniformity testing. meanwhile, the most natural learning algorithm is shown to have order - optimal sample complexity for all $ \ ell _ p $ metrics. the author thanks cl \ ' { e } ment canonne for discussions and contributions to this work.
|
arxiv:1412.2314
|
let g be a connected reductive group ( over $ \ mathbb { c } $ ) and h a connected semisimple subgroup. the dimension data of h ( realative to its given embedding in g ) is the collection of the numbers $ \ { { \ rm dim } v ^ { h } \ } $, where v runs over all the finite dimensional representations of g. by a theorem of larsen - pink ( [ l - p90 ] ), the dimension data determines h up to isomorphism, and if g = gl ( n ) even up to conjugacy. professor langlands raised the question as to whether the strong ( conjugacy ) result holds for arbitrary g. in this paper we provided the following ( negative ) answer : if h is simple of type a _ { 4 n }, $ b _ { 2 n } ( n \ geq 2 ) $, $ c _ { 2 n } ( n \ geq 2 ) $, e _ { 6 }, e _ { 8 }, f _ { 4 } and g _ { 2 }, then there exist ( for suitable $ n $ ) pairs of embeddings i and i ' of h into $ g = so ( 2 n ) $ such that there image i ( h ) and i ' ( h ) have the same dimension data but are not conjugate. in fact we have shown that i ( h ) and i ' ( h ) are \ emph { locally conjugate }, i. e., that i ( h ) and i ' ( h ) are conjugate in g for all semisimple $ h \ in h $. if one assumes functoriality, this result will furnish the failure of multiplicity one for automorphic forms on such g over global fields. such things are known in the disconnected cases, especially when h is finite, as in the works of blasius [ blasius94 ] for $ sl ( n ) ( n \ geq 3 ) $ and gan - gurevich - jiang2002 ( [ gan ] ) for g _ { 2 }.
|
arxiv:0707.0144
|
environmental technology ( or envirotech ) is the use of engineering and technological approaches to understand and address issues that affect the environment with the aim of fostering environmental improvement. it involves the application of science and technology in the process of addressing environmental challenges through environmental conservation and the mitigation of human impact to the environment. the term is sometimes also used to describe sustainable energy generation technologies such as photovoltaics, wind turbines, etc. = = purification and waste management = = = = = water purification = = = = = = air purification = = = air purification describes the processes used to remove contaminants and pollutants from the air to reduce the potential adverse effects on humans and the environment. the process of air purification may be performed using methods such as mechanical filtration, ionization, activated carbon adsorption, photocatalytic oxidation, and ultraviolet light germicidal irradiation. = = = sewage treatment = = = = = = environmental remediation = = = environmental remediation is the process through which contaminants or pollutants in soil, water and other media are removed to improve environmental quality. the main focus is the reduction of hazardous substances within the environment. some of the areas involved in environmental remediation include ; soil contamination, hazardous waste, groundwater contamination, oil, gas and chemical spills. there are three most common types of environmental remediation. these include soil, water, and sediment remediation. soil remediation consists of removing contaminants in soil, as these pose great risks to humans and the ecosystem. some examples of this are heavy metals, pesticides, and radioactive materials. depending on the contaminant the remedial processes can be physical, chemical, thermal, or biological. water remediation is one of the most important considering water is an essential natural resource. depending on the source of water there will be different contaminants. surface water contamination mainly consists of agricultural, animal, and industrial waste, as well as acid mine drainage. there has been a rise in the need for water remediation due to the increased discharge of industrial waste, leading to a demand for sustainable water solutions. the market for water remediation is expected to consistently increase to $ 19. 6 billion by 2030. sediment remediation consists of removing contaminated sediments. is it almost similar to soil remediation except it is often more sophisticated as it involves additional contaminants. to reduce the contamina
|
https://en.wikipedia.org/wiki/Environmental_technology
|
we show that large language models ( llms ) are remarkably good at working with interpretable models that decompose complex outcomes into univariate graph - represented components. by adopting a hierarchical approach to reasoning, llms can provide comprehensive model - level summaries without ever requiring the entire model to fit in context. this approach enables llms to apply their extensive background knowledge to automate common tasks in data science such as detecting anomalies that contradict prior knowledge, describing potential reasons for the anomalies, and suggesting repairs that would remove the anomalies. we use multiple examples in healthcare to demonstrate the utility of these new capabilities of llms, with particular emphasis on generalized additive models ( gams ). finally, we present the package $ \ texttt { talktoebm } $ as an open - source llm - gam interface.
|
arxiv:2308.01157
|
in recent years there has been great interest in using deep neural networks ( dnn ) for super - resolution image reconstruction including for structured illumination microscopy ( sim ). while these methods have shown very promising results, they all rely on data - driven, supervised training strategies that need a large number of ground truth images, which is experimentally difficult to realize. for sim imaging, there exists a need for a flexible, general, and open - source reconstruction method that can be readily adapted to different forms of structured illumination. we demonstrate that we can combine a deep neural network with the forward model of the structured illumination process to reconstruct sub - diffraction images without training data. the resulting physics - informed neural network ( pinn ) can be optimized on a single set of diffraction limited sub - images and thus doesn ' t require any training set. we show with simulated and experimental data that this pinn can be applied to a wide variety of sim methods by simply changing the known illumination patterns used in the loss function and can achieve resolution improvements that match well with theoretical expectations.
|
arxiv:2207.07705
|
auxiliary tasks improve the representations learned by deep reinforcement learning agents. analytically, their effect is reasonably well understood ; in practice, however, their primary use remains in support of a main learning objective, rather than as a method for learning representations. this is perhaps surprising given that many auxiliary tasks are defined procedurally, and hence can be treated as an essentially infinite source of information about the environment. based on this observation, we study the effectiveness of auxiliary tasks for learning rich representations, focusing on the setting where the number of tasks and the size of the agent ' s network are simultaneously increased. for this purpose, we derive a new family of auxiliary tasks based on the successor measure. these tasks are easy to implement and have appealing theoretical properties. combined with a suitable off - policy learning rule, the result is a representation learning algorithm that can be understood as extending mahadevan & maggioni ( 2007 ) ' s proto - value functions to deep reinforcement learning - - accordingly, we call the resulting object proto - value networks. through a series of experiments on the arcade learning environment, we demonstrate that proto - value networks produce rich features that may be used to obtain performance comparable to established algorithms, using only linear approximation and a small number ( ~ 4m ) of interactions with the environment ' s reward function.
|
arxiv:2304.12567
|
named entity recognition ( ner ) is a fundamental natural language processing ( nlp ) task to extract entities from unstructured data. the previous methods for ner were based on machine learning or deep learning. recently, pre - training models have significantly improved performance on multiple nlp tasks. in this paper, firstly, we introduce the architecture and pre - training tasks of four common pre - training models : bert, ernie, ernie2. 0 - tiny, and roberta. then, we apply these pre - training models to a ner task by fine - tuning, and compare the effects of the different model architecture and pre - training tasks on the ner task. the experiment results showed that roberta achieved state - of - the - art results on the msra - 2006 dataset.
|
arxiv:2002.08902
|
one of the basic questions of phylogenomics is how gene function evolves, whether among species or inside gene families. in this chapter, we provide a brief overview of the problems associated with defining gene function in a manner which allows comparisons which are both large scale and evolutionarily relevant. the main source of functional data, despite its limitations, is transcriptomics. functional data provides information on evolutionary mechanisms primarily by showing which functional classes of genes evolve under stronger or weaker purifying or adaptive selection, and on which classes of mutations ( e. g., substitutions or duplications ). however, the example of the " ortholog conjecture " shows that we are still not at a point where we can confidently study phylogenomically the evolution of gene function at a precise scale.
|
arxiv:1910.01940
|
engineering physics ( ep ), sometimes engineering science, is the field of study combining pure science disciplines ( such as physics, mathematics, chemistry or biology ) and engineering disciplines ( computer, nuclear, electrical, aerospace, medical, materials, mechanical, etc. ). in many languages, the term technical physics is also used. it has been used since 1861 by the german physics teacher j. frick in his publications. = = terminology = = in some countries, both what would be translated as " engineering physics " and what would be translated as " technical physics " are disciplines leading to academic degrees. in china, for example, with the former specializing in nuclear power research ( i. e. nuclear engineering ), and the latter closer to engineering physics. in some universities and their institutions, an engineering physics ( or applied physics ) major is a discipline or specialization within the scope of engineering science, or applied science. several related names have existed since the inception of the interdisciplinary field. for example, some university courses are called or contain the phrase " physical technologies " or " physical engineering sciences " or " physical technics ". in some cases, a program formerly called " physical engineering " has been renamed " applied physics " or has evolved into specialized fields such as " photonics engineering ". = = expertise = = unlike traditional engineering disciplines, engineering science or engineering physics is not necessarily confined to a particular branch of science, engineering or physics. instead, engineering science or engineering physics is meant to provide a more thorough grounding in applied physics for a selected specialty such as optics, quantum physics, materials science, applied mechanics, electronics, nanotechnology, microfabrication, microelectronics, computing, photonics, mechanical engineering, electrical engineering, nuclear engineering, biophysics, control theory, aerodynamics, energy, solid - state physics, etc. it is the discipline devoted to creating and optimizing engineering solutions through enhanced understanding and integrated application of mathematical, scientific, statistical, and engineering principles. the discipline is also meant for cross - functionality and bridges the gap between theoretical science and practical engineering with emphasis in research and development, design, and analysis. = = degrees = = in many universities, engineering science programs may be offered at the levels of b. tech., b. sc., m. sc. and ph. d. usually, a core of basic and advanced courses in mathematics, physics, chemistry, and biology forms the foundation of the curriculum, while typical elective areas may include fluid dynamics, quantum physics, economics,
|
https://en.wikipedia.org/wiki/Engineering_physics
|
we consider three problems for the helmholtz equation in interior and exterior domains in r ^ d ( d = 2, 3 ) : the exterior dirichlet - to - neumann and neumann - to - dirichlet problems for outgoing solutions, and the interior impedance problem. we derive sharp estimates for solutions to these problems that, in combination, give bounds on the inverses of the combined - field boundary integral operators for exterior helmholtz problems.
|
arxiv:1504.01037
|
in the born - infeld ' harmonic gauge ' description of m - branes moving in r ^ { m + 1 } the underlying m + 2 dimensional poincare - invariance gives rise to an interesting system of conservation laws showing signs of integrability.
|
arxiv:0806.0656
|
soft and collinear radiation is responsible for large corrections to many hadronic cross sections, near thresholds for the production of heavy final states. there is much interest in extending our understanding of this radiation to next - to - leading power ( nlp ) in the threshold expansion. in this paper, we generalise a previously proposed all - order nlp factorisation formula to include non - abelian corrections. we define a non - abelian radiative jet function, organising collinear enhancements at nlp, and compute it for quark jets at one loop. we discuss in detail the issue of double counting between soft and collinear regions. finally, we verify our prescription by reproducing all nlp logarithms in drell - yan production up to nnlo, including those associated with double real emission. our results constitute an important step in the development of a fully general resummation formalism for nlp threshold effects.
|
arxiv:1610.06842
|
the description of superconductivity at high temperature is a problem that has recently been addressed. transition temperature of superconductivity, $ t _ c $, depends on the lattice structure type, size, and room pressure. in super - lattices and low dimensional layered nanostructures, $ t _ c $ is increased, by increasing the complexity of the structure and internal pressures in solid lattice. in this paper, we investigate the relation between physical parameters ( $ \ epsilon, \ mu $ ) of matter and superconductivity properties as well as transition temperature ( $ t _ c $ ), and explain the superconductivity at high temperature. in this study, a semi - classical electromagnetic description along with vortex topologic theory and quantum dynamic models with experimental data considered to justify the relation between superconductivity phenomena and magnetic monopole properties. we find that the electromagnetic energy of magnetic monopole is in agreement with vortex energy in topological theory and it can get close to thermal energy at high temperature. these models suggest the superconductivity is related to the mobile monopole or vortices. we show that the electrical permittivity ( $ \ epsilon $ ) and magnetic permeability ( $ \ mu $ ) of matter have a key role in the superconductive properties.
|
arxiv:1704.02228
|
we introduce a notion of l - dendriform algebra due to several different motivations. l - dendriform algebras are regarded as the underlying algebraic structures of pseudo - hessian structures on lie groups and the algebraic structures behind the $ \ mathcal o $ - operators of pre - lie algebras and the related $ s $ - equation. as a direct consequence, they provide some explicit solutions of $ s $ - equation in certain pre - lie algebras constructed from l - dendriform algebras. they also fit into a bigger framework as lie algebraic analogues of dendriform algebras. moreover, we introduce a notion of $ \ mathcal o $ - operator of an l - dendriform algebra which gives an algebraic equation regarded as an analogue of the classical yang - baxter equation in a lie algebra.
|
arxiv:1104.0281
|
a novel space - time discretization for the ( linear ) scalar - valued dissipative wave equation is presented. it is a structured approach, namely, the discretization space is obtained tensorizing the virtual element ( ve ) discretization in space with the discontinuous galerkin ( dg ) method in time. as such, it combines the advantages of both the ve and the dg methods. the proposed scheme is implicit and it is proved to be unconditionally stable and accurate in space and time.
|
arxiv:2303.17391
|
as a potential solution for low - cost efficient solar cells, radial junctions consisting of zno nanowires arrays embedded in cu2o thin films have been theoretically modeled. calculations have been performed to explore the geometric dependence of performance of such wire - based solar cells. by properly setting material properties and cell dimensions, a reasonable power conversion efficiency of 19. 7 % can be expected in a material with 2 { \ mu } m minority carrier diffusion length. the detrimental effects of bulk, interface and contact - related states on solar cell performance have also been studied, from which the efficiencies between ~ 22 % and ~ 12 % for a series of materials, ranging from optimal to seriously poor - quality, are extracted. the findings suggest that rational device design plays a crucial role in implementing efficient cu2o / zno wire radial junction solar cells.
|
arxiv:1012.1927
|
large language models ( llms ) offer powerful capabilities but also introduce significant risks. one way to mitigate these risks is through comprehensive pre - deployment evaluations using benchmarks designed to test for specific vulnerabilities. however, the rapidly expanding body of llm benchmark literature lacks a standardized method for documenting crucial benchmark details, hindering consistent use and informed selection. benchmarkcards addresses this gap by providing a structured framework specifically for documenting llm benchmark properties rather than defining the entire evaluation process itself. benchmarkcards do not prescribe how to measure or interpret benchmark results ( e. g., defining ` ` correctness ' ' ) but instead offer a standardized way to capture and report critical characteristics like targeted risks and evaluation methodologies, including properties such as bias and fairness. this structured metadata facilitates informed benchmark selection, enabling researchers to choose appropriate benchmarks and promoting transparency and reproducibility in llm evaluation.
|
arxiv:2410.12974
|
in this paper, a multipurpose bayesian - based method for data analysis, causal inference and prediction in the sphere of oil and gas reservoir development is considered. this allows analysing parameters of a reservoir, discovery dependencies among parameters ( including cause and effects relations ), checking for anomalies, prediction of expected values of missing parameters, looking for the closest analogues, and much more. the method is based on extended algorithm mixlearn @ bn for structural learning of bayesian networks. key ideas of mixlearn @ bn are following : ( 1 ) learning the network structure on homogeneous data subsets, ( 2 ) assigning a part of the structure by an expert, and ( 3 ) learning the distribution parameters on mixed data ( discrete and continuous ). homogeneous data subsets are identified as various groups of reservoirs with similar features ( analogues ), where similarity measure may be based on several types of distances. the aim of the described technique of bayesian network learning is to improve the quality of predictions and causal inference on such networks. experimental studies prove that the suggested method gives a significant advantage in missing values prediction and anomalies detection accuracy. moreover, the method was applied to the database of more than a thousand petroleum reservoirs across the globe and allowed to discover novel insights in geological parameters relationships.
|
arxiv:2103.01804
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.