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even in a carefully designed randomized trial, outcomes for some study participants can be missing, or more precisely, ill - defined, because participants had died prior to date of outcome collection. this problem, known as truncation by death, means that the treated and untreated are no longer balanced with respect to covariates determining survival. therefore, researchers often utilize principal stratification and focus on the survivor average causal effect ( sace ). the sace is the average causal effect among the subpopulation that will survive regardless of treatment status. in this paper, we present matching - based methods for sace identification and estimation. we provide an identification result for the sace that motivates the use of matching to restore the balance among the survivors. we discuss various practical issues, including the choice of distance measures, possibility of matching with replacement, and post - matching crude and model - based sace estimators. simulation studies and data analysis demonstrate the flexibility of our approach. because the cross - world assumptions needed for sace identification can be too strong, we also present sensitivity analysis techniques and illustrate their use in real data analysis. finally, we show how our approach can also be utilized to estimate conditional separable effects, a recently - proposed alternative for the sace.
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arxiv:2110.10186
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it is known that representations from self - supervised pre - training can perform on par, and often better, on various downstream tasks than representations from fully - supervised pre - training. this has been shown in a host of settings such as generic object classification and detection, semantic segmentation, and image retrieval. however, some issues have recently come to the fore that demonstrate some of the failure modes of self - supervised representations, such as performance on non - imagenet - like data, or complex scenes. in this paper, we show that self - supervised representations based on the instance discrimination objective lead to better representations of objects that are more robust to changes in the viewpoint and perspective of the object. we perform experiments of modern self - supervised methods against multiple supervised baselines to demonstrate this, including approximating object viewpoint variation through homographies, and real - world tests based on several multi - view datasets. we find that self - supervised representations are more robust to object viewpoint and appear to encode more pertinent information about objects that facilitate the recognition of objects from novel views.
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arxiv:2208.00787
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i discuss the conformal approach to the numerical simulation of radiating isolated systems in general relativity. the method is based on conformal compactification and a reformulation of the einstein equations in terms of rescaled variables, the so - called ` ` conformal field equations ' ' developed by friedrich. these equations allow to include ` ` infinity ' ' on a finite grid, solving regular equations, whose solutions give rise to solutions of the einstein equations of ( vacuum ) general relativity. the conformal approach promises certain advantages, in particular with respect to the treatment of radiation extraction and boundary conditions. i will discuss the essential features of the analytical approach to the problem, previous work on the problem - in particular a code for simulations in 3 + 1 dimensions, some new results, open problems and strategies for future work.
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arxiv:gr-qc/0204057
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for zero energy, $ e = 0 $, we derive exact, classical solutions for { \ em all } power - law potentials, $ v ( r ) = - \ gamma / r ^ \ nu $, with $ \ gamma > 0 $ and $ - \ infty < \ nu < \ infty $. when the angular momentum is non - zero, these solutions lead to the orbits $ \ r ( t ) = [ \ cos \ mu ( \ th ( t ) - \ th _ 0 ( t ) ) ] ^ { 1 / \ mu } $, for all $ \ mu \ equiv \ nu / 2 - 1 \ ne 0 $. when $ \ nu > 2 $, the orbits are bound and go through the origin. this leads to discrete discontinuities in the functional dependence of $ \ th ( t ) $ and $ \ th _ 0 ( t ) $, as functions of $ t $, as the orbits pass through the origin. we describe a procedure to connect different analytic solutions for successive orbits at the origin. we calculate the periods and precessions of these bound orbits, and graph a number of specific examples. also, we explain why they all must violate the virial theorem. the unbound orbits are also discussed in detail. this includes the unusual orbits which have finite travel times to infinity and also the special $ \ nu = 2 $ case.
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arxiv:hep-th/9408057
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in this work we argue that, in the interpretation of the energy dependence of the depth of the shower maximum and of the muon content in high energy cosmic ray showers ( $ e > 10 ^ { 17 } $ ev ), other variables besides the composition may play an important role, in particular those characterising the first ( high energy ) hadronic collisions. the role of the inelasticity, of the nature of the leading particle, and of the particle multiplicity are discussed. a consistent interpretation of existing data within a string percolation model implemented in a hybrid, one dimensional simulation method is given.
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arxiv:hep-ph/0608050
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a retiree ' s appetite for risk is a common input into the lifetime utility models that are traditionally used to find optimal strategies for the decumulation of retirement savings. in this work, we consider a retiree with potentially differing appetites for the key financial risks of decumulation : liquidity risk and investment risk. we set out to determine whether these differing risk appetites have a significant impact on the retiree ' s optimal choice of decumulation strategy. to do so, we design and implement a framework which selects the optimal decumulation strategy from a general set of admissible strategies in line with a retiree ' s goals, and under differing appetites for the key risks of decumulation. overall, we find significant evidence to suggest that a retiree ' s differing appetites for different decumulation risks will impact their optimal choice of strategy at retirement. through an illustrative example calibrated to the australian context, we find results which are consistent with actual behaviours in this jurisdiction ( in particular, a shallow market for annuities ), which lends support to our framework and may provide some new insight into the so - called annuity puzzle.
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arxiv:2312.14355
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an electron - phonon interaction arising from the modulation of the superexchange interaction by phonons is studied within the theoretical framework of kondo lattices. it is relevant in strongly correlated electron liquids in cuprate oxide superconductors, which lie in the vicinity of the mott - hubbard metal - insulator transition. it is enhanced by antiferromagnetic and superconducting fluctuations, which are developed mainly because of the superexchange interaction. when the enhancement of the electron - phonon interaction is large enough, it can explain the softening of phonons and kinks in the quasiparticle dispersion in cuprate oxide superconductors. however, the superexchange interaction itself must be mainly responsible for the formation of cooper pairs.
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arxiv:cond-mat/0405703
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##swissenschaften. : p. 14 in recent years, ' human science ' has been used to refer to " a philosophy and approach to science that seeks to understand human experience in deeply subjective, personal, historical, contextual, cross - cultural, political, and spiritual terms. human science is the science of qualities rather than of quantities and closes the subject - object split in science. in particular, it addresses the ways in which self - reflection, art, music, poetry, drama, language and imagery reveal the human condition. by being interpretive, reflective, and appreciative, human science re - opens the conversation among science, art, and philosophy. " = = objective vs. subjective experiences = = since auguste comte, the positivistic social sciences have sought to imitate the approach of the natural sciences by emphasizing the importance of objective external observations and searching for universal laws whose operation is predicated on external initial conditions that do not take into account differences in subjective human perception and attitude. critics argue that subjective human experience and intention plays such a central role in determining human social behavior that an objective approach to the social sciences is too confining. rejecting the positivist influence, they argue that the scientific method can rightly be applied to subjective, as well as objective, experience. the term subjective is used in this context to refer to inner psychological experience rather than outer sensory experience. it is not used in the sense of being prejudiced by personal motives or beliefs. = = human science in universities = = since 1878, the university of cambridge has been home to the moral sciences club, with strong ties to analytic philosophy. the human science degree is relatively young. it has been a degree subject at oxford since 1969. at university college london, it was proposed in 1973 by professor j. z. young and implemented two years later. his aim was to train general science graduates who would be scientifically literate, numerate and easily able to communicate across a wide range of disciplines, replacing the traditional classical training for higher - level government and management careers. central topics include the evolution of humans, their behavior, molecular and population genetics, population growth and aging, ethnic and cultural diversity, and human interaction with the environment, including conservation, disease, and nutrition. the study of both biological and social disciplines, integrated within a framework of human diversity and sustainability, should enable the human scientist to develop professional competencies suited to address such multidimensional human problems. in the united kingdom, human science is offered at the degree
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https://en.wikipedia.org/wiki/Human_science
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as a predictor ' s quality is often assessed by means of its risk, it is natural to regard risk consistency as a desirable property of learning methods, and many such methods have indeed been shown to be risk consistent. the first aim of this paper is to establish the close connection between risk consistency and $ l _ p $ - consistency for a considerably wider class of loss functions than has been done before. the attempt to transfer this connection to shifted loss functions surprisingly reveals that this shift does not reduce the assumptions needed on the underlying probability measure to the same extent as it does for many other results. the results are applied to regularized kernel methods such as support vector machines.
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arxiv:2303.15210
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we study a model of $ f ( r ) $ gravity in which a crossing of the phantom divide can be realized. in particular, we demonstrate the behavior of $ f ( r ) $ gravity around a crossing of the phantom divide by taking into account the presence of cold dark matter.
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arxiv:0909.2991
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short - ranged and line - gapped non - hermitian hamiltonians have strong topological invariants given by an index of an associated fredholm operator. it is shown how these invariants can be accessed via the signature of a suitable spectral localizer. this numerical technique is implemented in an example with relevance to the design of topological photonic systems, such as topological lasers.
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arxiv:2303.09626
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statistical isotropy ( si ) has been one of the simplifying assumptions in cosmological model building. experiments like wmap and planck are attempting to test this assumption by searching for specific signals in the cosmic microwave background ( cmb ) two point correlation function. modifications to this correlation function due to gravitational lensing by the large scale structure ( lss ) surrounding us have been ignored in this context. gravitational lensing will induce signals which mimic isotropy violation even in an isotropic universe. the signal detected in the bipolar spherical harmonic ( biposh ) coefficients $ a ^ { 20 } _ { ll } $ by the wmap team may be explained by accounting for the lensing modifications to these coefficients. further the difference in the amplitude of the signal detected in the v - band and w - band maps can be explained by accounting for the differences in the designed angular sensitivity of the instrumental beams. the arguments presented in this article have crucial implications for si violation studies. constraining si violation will only be possible by complementing cmb data sets with all sky measurements of the large scale dark matter distribution. till that time, the signal detected in the biposh coefficients from wmap - 7 could also be yet another suggested evidence of strong deviations from the standard $ \ lambda $ cdm cosmology based on homogeneous and isotropic frw models.
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arxiv:1111.3357
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after many years of development of the basic tools, quantum simulation with ultracold atoms has now reached the level of maturity where it can be used to investigate complex quantum processes. planning of new experiments and upgrading existing set - ups depends crucially on a broad overview of the available techniques, their specific advantages and limitations. this technical review aims to provide a comprehensive compendium of the state of the art. we discuss the basic principles, the available techniques and their current range of applications. focusing on the simulation of varied phenomena in solid - state physics using optical lattice experiments, we review their basics, the necessary techniques and the accessible physical parameters. we outline how to control and use interactions with external potentials and between the atoms, and how to design new synthetic gauge fields and spin - orbit coupling. we discuss the latest progress in site - resolved techniques using quantum gas microscopes, and describe the unique features of quantum simulation experiments with two - electron atomic species.
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arxiv:2006.06120
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based on the framework of kubo formulism, we develop the minimally entangled typical thermal state algorithm to study the temperature and time dependence of current - current correlation function in one - dimensional spinless fermion model, taking into account both the electron - electron ( e - e ) intersite interaction and the dynamic disorder induced by classical phonons. without e - e interaction, the numerical results, showing an exponential decay of the time dependent correlation, could be precisely compared with that from the analytical derivation, namely, from the generalized langevin equation. more importantly, when a strong enough e - e interaction is presence, we find a long - time correlation in the regime of small dynamic disorder, indicating the breakdown of thermal relaxation, which is a typical many - body effect. on the basis of this finding, we show that it might be applied to understand the metalliclike charge transport and the abnormal improvement of the conductivity with respect to the redoping experiment in k $ _ 3 $ c $ _ { 60 } $, an organic superconducting material.
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arxiv:1206.4372
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context : developers use bad code smells to guide code reorganization. yet developers, text books, tools, and researchers disagree on which bad smells are important. objective : to evaluate the likelihood that a code reorganization to address bad code smells will yield improvement in the defect - proneness of the code. method : we introduce xtree, a tool that analyzes a historical log of defects seen previously in the code and generates a set of useful code changes. any bad smell that requires changes outside of that set can be deprioritized ( since there is no historical evidence that the bad smell causes any problems ). evaluation : we evaluate xtree ' s recommendations for bad smell improvement against recommendations from previous work ( shatnawi, alves, and borges ) using multiple data sets of code metrics and defect counts. results : code modules that are changed in response to xtree ' s recommendations contain significantly fewer defects than recommendations from previous studies. further, xtree endorses changes to very few code metrics, and the bad smell recommendations ( learned from previous studies ) are not universal to all software projects. conclusion : before undertaking a code reorganization based on a bad smell report, use a tool like xtree to check and ignore any such operations that are useless ; i. e. ones which lack evidence in the historical record that it is useful to make that change. note that this use case applies to both manual code reorganizations proposed by developers as well as those conducted by automatic methods. this recommendation assumes that there is an historical record. if none exists, then the results of this paper could be used as a guide.
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arxiv:1609.03614
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we study the singularity formation of strong solutions to the two - dimensional ( 2d ) cauchy problem of the non - baratropic compressible magnetohydrodynamic equations without heat conductivity. it is proved that the strong solution exists globally if the density and the pressure are bounded from above. in particular, the criterion is independent of the magnetic field and is just the same as that of the compressible navier - stokes equations. our method relies on weighted energy estimates and a hardy - type inequality.
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arxiv:1801.10036
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, and obtain indications of possible proofs. = = ancient greece = = most civilisations developed some mathematics, mainly for practical purposes, such as counting ( merchants ), surveying ( delimitation of fields ), prosody, astronomy, and astrology. it seems that ancient greek philosophers were the first to study the nature of mathematics and its relation with the real world. zeno of elea ( c. 490 – c. 430 bc ) produced several paradoxes he used to support his thesis that movement does not exist. these paradoxes involve mathematical infinity, a concept that was outside the mathematical foundations of that time and was not well understood before the end of the 19th century. the pythagorean school of mathematics originally insisted that the only numbers are natural numbers and ratios of natural numbers. the discovery ( c. 5th century bc ) that the ratio of the diagonal of a square to its side is not the ratio of two natural numbers was a shock to them which they only reluctantly accepted. a testimony of this is the modern terminology of irrational number for referring to a number that is not the quotient of two integers, since " irrational " means originally " not reasonable " or " not accessible with reason ". the fact that length ratios are not represented by rational numbers was resolved by eudoxus of cnidus ( 408 – 355 bc ), a student of plato, who reduced the comparison of two irrational ratios to comparisons of integer multiples of the magnitudes involved. his method anticipated that of dedekind cuts in the modern definition of real numbers by richard dedekind ( 1831 – 1916 ) ; see eudoxus of cnidus § eudoxus ' proportions. in the posterior analytics, aristotle ( 384 – 322 bc ) laid down the logic for organizing a field of knowledge by means of primitive concepts, axioms, postulates, definitions, and theorems. aristotle took a majority of his examples for this from arithmetic and from geometry, and his logic served as the foundation of mathematics for centuries. this method resembles the modern axiomatic method but with a big philosophical difference : axioms and postulates were supposed to be true, being either self - evident or resulting from experiments, while no other truth than the correctness of the proof is involved in the axiomatic method. so, for aristotle, a proved theorem is true, while in the axiomatic methods, the proof says only that the axioms imply the statement of the theorem. aristotle ' s logic reached its
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https://en.wikipedia.org/wiki/Foundations_of_mathematics
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recognition of hungarian conversational telephone speech is challenging due to the informal style and morphological richness of the language. recurrent neural network language model ( rnnlm ) can provide remedy for the high perplexity of the task ; however, two - pass decoding introduces a considerable processing delay. in order to eliminate this delay we investigate approaches aiming at the complexity reduction of rnnlm, while preserving its accuracy. we compare the performance of conventional back - off n - gram language models ( bnlm ), bnlm approximation of rnnlms ( rnn - bnlm ) and rnn n - grams in terms of perplexity and word error rate ( wer ). morphological richness is often addressed by using statistically derived subwords - morphs - in the language models, hence our investigations are extended to morph - based models, as well. we found that using rnn - bnlms 40 % of the rnnlm perplexity reduction can be recovered, which is roughly equal to the performance of a rnn 4 - gram model. combining morph - based modeling and approximation of rnnlm, we were able to achieve 8 % relative wer reduction and preserve real - time operation of our conversational telephone speech recognition system.
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arxiv:1907.06407
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balancing competing objectives remains a fundamental challenge in multi - task learning ( mtl ), primarily due to conflicting gradients across individual tasks. a common solution relies on computing a dynamic gradient update vector that balances competing tasks as optimization progresses. building on this idea, we propose conicgrad, a principled, scalable, and robust mtl approach formulated as a constrained optimization problem. our method introduces an angular constraint to dynamically regulate gradient update directions, confining them within a cone centered on the reference gradient of the overall objective. by balancing task - specific gradients without over - constraining their direction or magnitude, conicgrad effectively resolves inter - task gradient conflicts. moreover, our framework ensures computational efficiency and scalability to high - dimensional parameter spaces. we conduct extensive experiments on standard supervised learning and reinforcement learning mtl benchmarks, and demonstrate that conicgrad achieves state - of - the - art performance across diverse tasks.
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arxiv:2502.00217
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we explore the effect of couette flow on knotted linear polymer chains with extensive molecular dynamics ( md ) simulations. hydrodynamic interactions are accounted for by means of multi - particle collision dynamics ( mpcd ). the polymer chain, containing originally a simple trefoil knot at rest, is described by a coarse - grained bead - spring model in a coil or globular state. we demonstrate that under shear existing loosely localized knots in polymer coils typically tighten to several segments beyond a certain shear rate threshold. at large shear rates the polymer undergoes a tumbling - like motion during which knot sizes can fluctuate. in contrast, sheared knotted globules unwind into a convoluted pearl - necklace structure of sub - globules that folds back onto itself and in which knot types change over time.
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arxiv:2412.06577
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the fermion spherical harmonics [ $ y _ \ ell ^ { m } ( \ theta, \ phi ) $ for half - odd - integer $ \ ell $ and $ m $ - presented in a previous paper ] are shown to have the same eigenfunction properties as the well - known boson spherical harmonics [ $ y _ \ ell ^ { m } ( \ theta, \ phi ) $ for integer $ \ ell $ and $ m $ ]. the fermion functions are shown to differ from the boson functions in so far as the ladder operators $ m _ + $ ( $ m _ - $ ) that ascend ( descend ) the sequence of harmonics over the values of $ m $ for a given value of $ \ ell $, do not produce the expected result { \ em in just one case } : when the value of $ m $ changes from $ \ pm { 1 / 2 } $ to $ \ mp { 1 / 2 } $ ; i. e. when $ m $ changes sign ; in all other cases the ladder operators produce the usually expected result including anihilation when a ladder operator attempts to take $ m $ outside the range : $ - \ ell \ le m \ le + \ ell $. the unexpected result in the one case does not invalidate this scalar coordinate representation of spin angular momentum, because the eigenfunction property is essential for a valid quantum mechanical state, whereas ladder operators relating states with different eigenvalues are not essential, and are in fact known only for a few physical systems ; that this coordinate representation of spin angular momentum differs from the abstract theory of angular momentum in this respect, is simply an interesting curiosity. this new representation of spin angular momentum is expected to find application in the theoretical description of physical systems and experiments in which the spin - angular momentum ( and associated magnetic moment ) of a particle is oriented in space, since the orientation is specifiable by the spherical polar angles, $ \ theta $ and $ \ phi $.
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arxiv:quant-ph/0507006
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360 { \ deg } cameras have gained popularity over the last few years. in this paper, we propose two fundamental techniques - - field - of - view iou ( fov - iou ) and 360augmentation for object detection in 360 { \ deg } images. although most object detection neural networks designed for the perspective images are applicable to 360 { \ deg } images in equirectangular projection ( erp ) format, their performance deteriorates owing to the distortion in erp images. our method can be readily integrated with existing perspective object detectors and significantly improves the performance. the fov - iou computes the intersection - over - union of two field - of - view bounding boxes in a spherical image which could be used for training, inference, and evaluation while 360augmentation is a data augmentation technique specific to 360 { \ deg } object detection task which randomly rotates a spherical image and solves the bias due to the sphere - to - plane projection. we conduct extensive experiments on the 360indoor dataset with different types of perspective object detectors and show the consistent effectiveness of our method.
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arxiv:2202.03176
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here we present a novel approach to conditioning the samplernn generative model for voice conversion ( vc ). conventional methods for vc modify the perceived speaker identity by converting between source and target acoustic features. our approach focuses on preserving voice content and depends on the generative network to learn voice style. we first train a multi - speaker samplernn model conditioned on linguistic features, pitch contour, and speaker identity using a multi - speaker speech corpus. voice - converted speech is generated using linguistic features and pitch contour extracted from the source speaker, and the target speaker identity. we demonstrate that our system is capable of many - to - many voice conversion without requiring parallel data, enabling broad applications. subjective evaluation demonstrates that our approach outperforms conventional vc methods.
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arxiv:1808.08311
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we consider a generalization of nonrelativistic schr \ " odinger - higgs lagrangian by introducing a nonstandard kinetic term. we show that this model is galilean invariant, we construct the conserved charges associated to the symmetries and realize the algebra of the galilean group. in addition, we study the model in the presence of a gauge field. we also show that the gauged model is galilean invariant. finally, we explore relations between twin models and their solutions.
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arxiv:1503.04844
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risk analytics is important to quantify, manage and analyse risks from the manufacturing to the financial setting. in this paper, the data challenges in the three stages of the high - performance risk analytics pipeline, namely risk modelling, portfolio risk management and dynamic financial analysis is presented.
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arxiv:1311.5685
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we present factorization theorems for two exclusive heavy - quarkonium production processes : production of two quarkonia in e ^ + e ^ - annihilation and production of a quarkonium and a light meson in b - meson decays. we describe the general proofs of factorization and supplement them with explicit one - loop analyses, which illustrate some of the features of the soft - gluon cancellations. we find that violations of factorization are generally suppressed relative to the factorized contributions by a factor v ^ 2m _ c / q for each s - wave charmonium and a factor m _ c / q for each l - wave charmonium with l > 0. here, v is the velocity of the heavy quark or antiquark in the quarkonium rest frame, q = sqrt { s } for e ^ + e ^ - annihilation, q = m _ b for b - meson decays, sqrt { s } is the e ^ + e ^ - center - of - momentum energy, m _ c is the charm - quark mass, and m _ b is the b - meson mass. there are modifications to the suppression factors if quantum - number restrictions apply for the specific process.
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arxiv:1003.0061
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commercially available business process management systems ( bpms ) still suffer to support organizations to enact their business processes in an effective and efficient way. current bpms, in general, are based on bpmn 2. 0 and / or bpel. it is well known, that these approaches have some restrictions according modeling and immediate transfer of the model into executable code. recently, a method for modeling and execution of business processes, named subject - oriented business process management ( s - bpm ), gained attention. this methodology facilitates modeling of any business process using only five symbols and allows direct execution based on such models. further on, this methodology has a strong theoretical and formal basis realizing distributed systems ; any process is defined as a network of independent and distributed agents - i. e. instances of subjects - which coordinate work through the exchange of messages. in this work, we present a framework and a prototype based on off - the - shelf technologies as a possible realization of the s - bpm methodology. we can prove and demonstrate the principal architecture concept ; these results should also stimulate a discussion about actual bpms and its underlying concepts.
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arxiv:1309.3126
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uncertainty propagates through calculations, down to molecular scales to infer microstructural features, and up to macroscopic scales with predictive flow simulations. here we study uncertainty quantification for sequential ( two - step ) versus simultaneous ( all at once ) fitting methods with linear and weakly - nonlinear rheological data. using an example of a combined dataset on small - amplitude oscillatory shear ( saos ) and medium - amplitude oscillatory shear ( maos ) for a linear entangled polymer melt ( cis - 1, 4 - polyisoprene ), we demonstrate with a multi - mode giesekus model how the fit parameter uncertainties are significantly under - estimated with the sequential fit because of the neglect of model parameter correlations. these results are surprising because weakly - nonlinear data is only an asymptotic step away from the linear data, yet it has significant impact on calibrating the linear model parameters. similarly, the nonlinear parameter estimates and uncertainties are impacted by considering the linear data in a simultaneous fit. to compare multi - mode spectra of nonlinear parameters ( mobility parameters { \ alpha _ i } from the giesekus model ), we derive new average measures based on moments of the spectra related to the high - frequency maos limit. the spectral averages are also sensitive to sequential versus simultaneous fitting. our results reveal the importance of using simultaneous fitting for honest uncertainty quantification, even with weakly - nonlinear data.
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arxiv:2202.02867
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class i cr manifolds have initial g - structure a certain 4 - dimensional subgroup of gl _ 3 ( c ). class ii cr manifolds have initial g - structure a certain 10 - dimensional subgroup of gl _ 4 ( c ). class iii - 1 cr manifolds have initial g - structure a certain 10 - dimensional subgroup of gl _ 5 ( c ). class iii - 2 cr manifolds have initial g - structure a certain 18 - dimensional subgroup of gl _ 5 ( c ). class iv - 1 cr manifolds have initial g - structure a certain 13 - dimensional subgroup of gl _ 5 ( c ). class iv - 2 cr manifolds have initial g - structure a certain 10 - dimensional subgroup of gl _ 5 ( c ).
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arxiv:1312.1084
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this paper is the first in a series of three. the main result, theorem 1. 11, gives an explicit description of the ergodic decomposition for infinite pickrell measures on spaces of infinite complex matrices. the main construction is that of sigma - finite analogues of determinantal measures on spaces of configurations. an example is the infinite bessel point process, the scaling limit of sigma - finite analogues of jacobi orthogonal polynomial ensembles. the statement of theorem 1. 11 is that the infinite bessel point process ( subject to an appropriate change of variables ) is precisely the ergodic decomposition measure for infinite pickrell measures.
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arxiv:1312.3161
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we obtain wave functionals of free real and complex scalar fields on a 1 + 1 dimensional lattice by explicitly calculating the path integral for transition from one field configuration to another. the obtained expressions are useful for cross - checking quality of approximations schemes used to study self - interacting fields on the lattice.
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arxiv:1404.5629
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we briefly review the topic of ads ( in ) stability, mainly focusing on a recently introduced analytic approach and its interplay with numerical results.
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arxiv:1510.07836
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for every positive integer $ n $ we construct a bigraded homology theory for links, such that the corresponding invariant of the unknot is closely related to the u ( n ) - equivariant cohomology ring of $ \ mathbb { cp } ^ { n - 1 } $ ; our construction specializes to the khovanov - rozansky $ sl _ n $ - homology. we are motivated by the " universal " rank two frobenius extension studied by m. khovanov in \ cite { kh3 } for $ sl _ 2 $ - homology.
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arxiv:0804.3751
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we discuss the fermion mass hierarchy and the flavor mixings in the fat brane scenario of five dimensional susy theory. the decoupling solution of the sfermion mass spectrum can be realized by introducing the vector - like mirror fields in an extra dimension. in this scenario, both the left - and right - handed sleptons can have sizable flavor mixings. we point out that this sizable flavor mixings can induce the suitable magnitude of the muon anomalous magnetic moment ( $ g _ \ mu - 2 $ ) within the experimental bounds of lepton flavor violating processes.
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arxiv:hep-ph/0209009
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light refraction, i. e. the bending of the path of a light wave at the interface between two different dielectric media, is ubiquitous in optics. refraction arises from the different speed of light and is unavoidable in continuous media according to snell ' s law. here we show rather counterintuitively that omnidirectional refractionless propagation can be observed for discretized light crossing a tilted interface separating two homogeneous waveguide lattices.
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arxiv:1711.06972
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we discuss properties of certain generalization of power means proposed in 1971 by carlson, meany and nelson. for any fixed parameter ( k, s, q ) and vector ( v _ 1,..., v _ n ) they take the q - th power means of all possible k - tuples ( v _ { i _ 1 },..., v _ { i _ k } ), and then calculate the s - th power mean of the resulting vector of length c _ n ^ k. we work towards a complete answer to the question when such means satisfy inequalities resembling the classical hardy inequality. we give a definitive answer in a large part of the parameter space. an unexpected corollary is that this family behaves much differently than most of other families admitting hardy - type inequalities. namely, arbitrarily small perturbations of parameters may lead to the breakdown of such inequalities.
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arxiv:1304.7448
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we present our submission to the semantic segmentation contest of the robust vision challenge held at eccv 2020. the contest requires submitting the same model to seven benchmarks from three different domains. our approach is based on the swiftnet architecture with pyramidal fusion. we address inconsistent taxonomies with a single - level 193 - dimensional softmax output. we strive to train with large batches in order to stabilize optimization of a hard recognition problem, and to favour smooth evolution of batchnorm statistics. we achieve this by implementing a custom backward step through log - sum - prob loss, and by using small crops before freezing the population statistics. our model ranks first on the rvc semantic segmentation challenge as well as on the wilddash 2 leaderboard. this suggests that pyramidal fusion is competitive not only for efficient inference with lightweight backbones, but also in large - scale setups for multi - domain application.
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arxiv:2009.01636
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tensor contraction ( tc ) is an important computational kernel widely used in numerous applications. it is a multi - dimensional generalization of matrix multiplication ( gemm ). while strassen ' s algorithm for gemm is well studied in theory and practice, extending it to accelerate tc has not been previously pursued. thus, we believe this to be the first paper to demonstrate how one can in practice speed up tensor contraction with strassen ' s algorithm. by adopting a block - scatter - matrix format, a novel matrix - centric tensor layout, we can conceptually view tc as gemm for a general stride storage, with an implicit tensor - to - matrix transformation. this insight enables us to tailor a recent state - of - the - art implementation of strassen ' s algorithm to tc, avoiding explicit transpositions ( permutations ) and extra workspace, and reducing the overhead of memory movement that is incurred. performance benefits are demonstrated with a performance model as well as in practice on modern single core, multicore, and distributed memory parallel architectures, achieving up to 1. 3x speedup. the resulting implementations can serve as a drop - in replacement for various applications with significant speedup.
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arxiv:1704.03092
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let $ t ( d, r ) = ( r - 1 ) ( d + 1 ) + 1 $ be the parameter in tverberg ' s theorem, and call a partition $ \ mathcal i $ of $ \ { 1, 2, \ ldots, t ( d, r ) \ } $ into $ r $ parts a " tverberg type ". we say that $ \ mathcal i $ " occurs " in an ordered point sequence $ p $ if $ p $ contains a subsequence $ p ' $ of $ t ( d, r ) $ points such that the partition of $ p ' $ that is order - isomorphic to $ \ mathcal i $ is a tverberg partition. we say that $ \ mathcal i $ is " unavoidable " if it occurs in every sufficiently long point sequence. in this paper we study the problem of determining which tverberg types are unavoidable. we conjecture a complete characterization of the unavoidable tverberg types, and we prove some cases of our conjecture for $ d \ le 4 $. along the way, we study the avoidability of many other geometric predicates. our techniques also yield a large family of $ t ( d, r ) $ - point sets for which the number of tverberg partitions is exactly $ ( r - 1 )! ^ d $. this lends further support for sierksma ' s conjecture on the number of tverberg partitions.
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arxiv:1611.01078
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include aluminium, chromium, copper, magnesium, nickel, titanium, zinc, and silicon. these metals are most often used as alloys with the noted exception of silicon, which is not a metal. other forms include : stainless steel, particularly austenitic stainless steels, galvanized steel, nickel alloys, titanium alloys, or occasionally copper alloys are used, where resistance to corrosion is important. aluminium alloys and magnesium alloys are commonly used, when a lightweight strong part is required such as in automotive and aerospace applications. copper - nickel alloys ( such as monel ) are used in highly corrosive environments and for non - magnetic applications. nickel - based superalloys like inconel are used in high - temperature applications such as gas turbines, turbochargers, pressure vessels, and heat exchangers. for extremely high temperatures, single crystal alloys are used to minimize creep. in modern electronics, high purity single crystal silicon is essential for metal - oxide - silicon transistors ( mos ) and integrated circuits. = = production = = in production engineering, metallurgy is concerned with the production of metallic components for use in consumer or engineering products. this involves production of alloys, shaping, heat treatment and surface treatment of product. the task of the metallurgist is to achieve balance between material properties, such as cost, weight, strength, toughness, hardness, corrosion, fatigue resistance and performance in temperature extremes. to achieve this goal, the operating environment must be carefully considered. determining the hardness of the metal using the rockwell, vickers, and brinell hardness scales is a commonly used practice that helps better understand the metal ' s elasticity and plasticity for different applications and production processes. in a saltwater environment, most ferrous metals and some non - ferrous alloys corrode quickly. metals exposed to cold or cryogenic conditions may undergo a ductile to brittle transition and lose their toughness, becoming more brittle and prone to cracking. metals under continual cyclic loading can suffer from metal fatigue. metals under constant stress at elevated temperatures can creep. = = = metalworking processes = = = casting – molten metal is poured into a shaped mold. variants of casting include sand casting, investment casting, also called the lost wax process, die casting, centrifugal casting, both vertical and horizontal, and continuous castings. each of these forms has advantages for certain metals and applications considering factors like magnetism and corrosion. forging – a red - hot billet is hammered into shape. rolling – a
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https://en.wikipedia.org/wiki/Metallurgy
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the synt workshop aims to bring together researchers interested in the broad area of synthesis of computing systems. the goal is to foster the development of frontier techniques in automating the development of computing system. contributions of interest include algorithms, complexity and decidability analysis, as well as reproducible heuristics, implemented tools, and experimental evaluation. application domains include software, hardware, embedded, and cyberphysical systems. computation models include functional, reactive, hybrid and timed systems. identifying, formalizing, and evaluating synthesis in particular application domains is encouraged. the fourth iteration of the workshop took place in san francisco, ca, usa. it was co - located with the 27th international conference on computer aided verification. the workshop included five contributed talks and two invited talks. in addition, it featured a special session about the syntax - guided synthesis competition ( sygus ) and the syntcomp synthesis competition.
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arxiv:1602.00786
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conditional quantiles provide a natural tool for reporting results from regression analyses based on semiparametric transformation models. we consider their estimation and construction of confidence sets in the presence of censoring.
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arxiv:math/0511508
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we present a study of the infrared variability of young stellar objects by means of two spitzer - irac images of the vela molecular cloud d ( vmr - d ) obtained in observations separated in time by about six months. by using the same space - born ir instrumentation, this study eliminates all the unwanted effects usually unavoidable when comparing catalogs obtained from different instruments. the vmr - d map covers about 1. 5 square deg. of a site where star formation is actively ongoing. we are interested in accreting pre - main sequence variables whose luminosity variations are due to intermittent events of disk accretion ( i. e. active t tauri stars and exor type objects ). the variable objects have been selected from a catalog of more than 170, 000 sources detected at a s / n ratio > 5. we searched the sample of variables for ones whose photometric properties are close to those of known exor ' s. these latter are monitored in a more systematic way than t tauri stars and the mechanisms that regulate the observed phenomenology are exactly the same. hence the modalities of the exor behavior is adopted as driving criterium for selecting variables in general. we selected 19 bona fide candidates that constitute a well - defined sample of new variable targets for further investigation. out of these, 10 sources present a spitzer mips 24 micron counterpart, and have been classified as 3 class i, 5 flat spectrum and 2 class ii objects, while the other 9 sources have spectral energy distribution compatible with phases older than class i. this is consistent with what is known about the small sample of known exor ' s, and suggests that the accretion flaring or exor stage might come as a class i / ii transition. we present also new prescriptions that can be useful in future searches for accretion variables in large ir databases.
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arxiv:0906.4060
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general - purpose large language models ( llms ) like gpt - 4 have achieved remarkable advancements in machine translation ( mt ) by leveraging extensive web content. on the other hand, translation - specific llms are built by pre - training on domain - specific monolingual corpora and fine - tuning with human - annotated translation data. despite the superior performance, these methods either demand an unprecedented scale of computing and data or substantial human editing and annotation efforts. in this paper, we develop mt - ladder, a novel model - agnostic and cost - effective tool to refine the performance of general llms for mt. mt - ladder is trained on pseudo - refinement triplets which can be easily obtained from existing llms without additional human cost. during training, we propose a hierarchical fine - tuning strategy with an easy - to - hard schema, improving mt - ladder ' s refining performance progressively. the trained mt - ladder can be seamlessly integrated with any general - purpose llms to boost their translation performance. by utilizing gemma - 2b / 7b as the backbone, mt - ladder - 2b can elevate raw translations to the level of top - tier open - source models ( e. g., refining bigtranslate - 13b with + 6. 91 bleu and + 3. 52 comet for xx - en ), and mt - ladder - 7b can further enhance model performance to be on par with the state - of - the - art gpt - 4. extensive ablation and analysis corroborate the effectiveness of mt - ladder in diverse settings. our code is available at https : / / github. com / fzp0424 / mt - ladder
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arxiv:2406.15741
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several mobile agent based distributed network management models have been proposed in recent times to address the scalability and flexibility problems of centralized ( snmp or cmip management models ) models. though the use of mobile agents to distribute and delegate management tasks comes handy in dealing with the previously stated issues, many of the agent - based management frameworks like initial flat bed models and static mid - level managers employing mobile agents models cannot efficiently meet the demands of current networks which are growing in size and complexity. moreover, varied technologies, such as sonet, atm, ethernet, dwdm etc., present at different layers of the access, metro and core ( long haul ) sections of the network, have contributed to the complexity in terms of their own framing and protocol structures. thus, controlling and managing the traffic in these networks is a challenging task. this paper presents an intelligent scalable hierarchical agent based model for the management of large - scale complex networks to address aforesaid issues. the cost estimation, carried out with a view to compute the overall management cost in terms of management data overhead, is being presented. the results obtained thereafter establish the usefulness of the presented architecture as compare to centralized and flat bed agent based models.
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arxiv:1202.1941
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we investigate degenerate cross - diffusion equations with a rank - deficient diffusion matrix that are considered to model populations which move as to avoid spatial crowding and have recently been found to arise in a mean - field limit of interacting stochastic particle systems. to date, their analysis in multiple space dimensions has been confined to the purely convective case with equal mobility coefficients. in this article, we introduce a normal form for an entropic class of such equations which reveals their structure of a symmetric hyperbolic - - parabolic system. due to the state - dependence of the range and kernel of the singular diffusive matrix, our way of rewriting the equations is different from that classically used for symmetric second - order systems with a nullspace invariance property. by means of this change of variables, we solve the cauchy problem for short times and positive initial data in $ h ^ s ( \ mathbb { t } ^ d ) $ for $ s > d / 2 + 1 $.
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arxiv:2210.17244
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we both show experimentally and numerically that the time scales separation introduced by long range activation can induce oscillations and excitability in nonequilibrium reaction - diffusion systems that would otherwise only exhibit bistability. namely, we show that the chlorite - tetrathionate reaction, where autocatalytic species diffuses faster than the substrates, the spatial bistability domain in the nonequilibrium phase diagram is extended with oscillatory and excitability domains. a simple model and a more realistic model qualitatively account for the observed behavior. the latter model provides quantitative agreement with the experiments.
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arxiv:nlin/0207031
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deep chandra observations of the core of the perseus cluster show a plethora of complex structure. it has been found that when the observed density fluctuations in the intracluster medium are converted into constraints on agn induced turbulence, the resulting turbulent heating rates are sufficient to balance cooling locally throughout the central 220kpc. however while the signatures of agn feedback ( inflated bubbles ) dominate the central 60kpc in x - ray images, beyond this radius the intracluster medium is increasingly shaped by the effects of gas sloshing, which can also produce subtle variations in x - ray surface brightness. we use mock chandra observations of gas sloshing simulations to investigate what fraction of the observed density fluctuations in the core of the perseus galaxy cluster may originate from sloshing rather than agn induced feedback. outside 60kpc, we find that the observed level of the density fluctuations is broadly consistent with being produced by sloshing alone. if this is the case, agn - generated turbulence is likely to be insufficient in combating cooling outside 60kpc.
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arxiv:1808.10460
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we present a kinematic analysis of the main - sequence galaxy hz4 at $ z = 5. 5 $. our study is based on deep, spatially resolved observations of the [ cii ] 158 $ \ mu $ m transition obtained with the atacama large millimeter / submillimeter array ( alma ). from the combined analysis of the disk morphology, the two - dimensional velocity structure, and forward - modeling of the one - dimensional velocity and velocity dispersion profiles, we conclude that hz4 has a regular rotating disk in place. the intrinsic velocity dispersion in hz4 is high ( $ \ sigma _ { 0 } = 65. 8 ^ { + 2. 9 } _ { - 3. 3 } $ km s $ ^ { - 1 } $ ), and the ratio between the rotational velocity and the intrinsic velocity dispersion is $ v _ { \ rm rot } / \ sigma _ { 0 } = 2. 2 $. these values are consistent with the expectations from the trends of increasing $ \ sigma _ { 0 } $ and decreasing $ v _ { \ rm rot } / \ sigma _ { 0 } $ as a function of redshift observed in main - sequence galaxies up to $ z \ approx4 $. galaxy evolution models suggest that the high level of turbulence observed in hz4 can only be achieved if, in addition to stellar feedback, there is radial transport of gas within the disk. finally, we find that hz4 is baryon dominated on galactic scales ( $ \ lesssim2 \ times r _ { \ rm e } $ ), with a dark matter fraction at one effective radius of $ f _ { \ rm dm } ( r _ { \ rm e } ) = 0. 41 ^ { + 0. 25 } _ { - 0. 22 } $. this value is comparable to the dark matter fractions found in lower redshift galaxies that could be the descendants of hz4 : massive ( $ m _ { \ star } \ approx10 ^ { 11 } ~ m _ { \ odot } $ ), star - forming galaxies at $ z \ sim2 $, and passive, early type galaxies at $ z \ approx0 $.
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arxiv:2203.00689
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since the birth of x - ray astronomy, spectral, spatial and timing observation improved dramatically, procuring a wealth of information on the majority of the classes of the celestial sources. polarimetry, instead, remained basically unprobed. x - ray polarimetry promises to provide additional information procuring two new observable quantities, the degree and the angle of polarization. polarix is a mission dedicated to x - ray polarimetry. it exploits the polarimetric response of a gas pixel detector, combined with position sensitivity, that, at the focus of a telescope, results in a huge increase of sensitivity. three gas pixel detectors are coupled with three x - ray optics which are the heritage of jet - x mission. polarix will measure time resolved x - ray polarization with an angular resolution of about 20 arcsec in a field of view of 15 arcmin $ \ times $ 15 arcmin and with an energy resolution of 20 % at 6 kev. the minimum detectable polarization is 12 % for a source having a flux of 1 mcrab and 10 ^ 5 s of observing time. the satellite will be placed in an equatorial orbit of 505 km of altitude by a vega launcher. the telemetry down - link station will be malindi. the pointing of polarix satellite will be gyroless and it will perform a double pointing during the earth occultation of one source, so maximizing the scientific return. polarix data are for 75 % open to the community while 25 % + svp ( science verification phase, 1 month of operation ) is dedicated to a core program activity open to the contribution of associated scientists. the planned duration of the mission is one year plus three months of commissioning and svp, suitable to perform most of the basic science within the reach of this instrument.
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arxiv:1105.0637
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we study oscillations in quantum cascade lasers due to traveling electric field domains, which are observed both in simulations and experiments. these oscillations occur in a range of negative differential resistance and we clarify the condition determining whether the boundary between domains of different electric field can become stationary.
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arxiv:1810.13207
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access to microarcsecond astrometry is now routine in the radio, infrared, and optical domains. in particular the publication of the second data release from the gaia mission made it possible for every astronomer to work with easily accessible, high - precision astrometry for 1. 7 billion sources to 21st magnitude over the full sky. * gaia provides splendid astrometry but at the limits of the data small systematic errors are present. a good understanding of the hipparcos / gaia astrometry concept, and of the data collection and processing, provides insights into the origins of the systematic errors and how to mitigate their effects. * a selected set of results from gaia highlight the breadth of exciting science and unexpected results, from the solar system to the distant universe, to creative uses of the data. * gaia dr2 provides for the first time a dense sampling of galactic phase space with high precision astrometry, photometry, and radial velocities, allowing to uncover subtle features in phase space and the observational hr diagram. * in the coming decade, we can look forward to more accurate and richer gaia data releases, and new photometric and spectroscopic surveys coming online that will provide essential complementary data. * the longer term promises exciting new opportunities for microarcsecond astrometry and beyond, including the plans for an infrared version of gaia which would offer the dense sampling of phase space deep into the milky way ' s nuclear regions.
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arxiv:2102.11712
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we analyze the ground state energy for n fermions in a two - dimensional box interacting with an impurity particle via two - body point interactions. we allow for mass ratios m > 1. 225 between the impurity mass and the mass of a fermion and consider arbitrarily large box sizes while keeping the fermi energy fixed. our main result shows that the ground state energy in the limit of weak coupling is given by the polaron energy. the polaron energy is an energy estimate based on trial states up to first order in particle - hole expansion, which was proposed by chevy in the physics literature. for the proof we apply a birman - schwinger principle that was recently obtained by griesemer and linden. one main new ingredient is a suitable localization of the polaron energy.
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arxiv:2012.09621
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this book introduces the mathematical foundations and techniques that lead to the development and analysis of many of the algorithms that are used in machine learning. it starts with an introductory chapter that describes notation used throughout the book and serve at a reminder of basic concepts in calculus, linear algebra and probability and also introduces some measure theoretic terminology, which can be used as a reading guide for the sections that use these tools. the introductory chapters also provide background material on matrix analysis and optimization. the latter chapter provides theoretical support to many algorithms that are used in the book, including stochastic gradient descent, proximal methods, etc. after discussing basic concepts for statistical prediction, the book includes an introduction to reproducing kernel theory and hilbert space techniques, which are used in many places, before addressing the description of various algorithms for supervised statistical learning, including linear methods, support vector machines, decision trees, boosting, or neural networks. the subject then switches to generative methods, starting with a chapter that presents sampling methods and an introduction to the theory of markov chains. the following chapter describe the theory of graphical models, an introduction to variational methods for models with latent variables, and to deep - learning based generative models. the next chapters focus on unsupervised learning methods, for clustering, factor analysis and manifold learning. the final chapter of the book is theory - oriented and discusses concentration inequalities and generalization bounds.
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arxiv:2409.02668
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we consider a position - dependent quantum walk on $ { \ bf z } $. in particular, we derive a detection method for edge defects by embedded eigenvalues of its time evolution operator. in the present paper, the set of edge defects is that of points in $ { \ bf z } $ on which the coin operator is an anti - diagonal matrix. in fact, under some suitable assumptions, the existence of a finite number of edge defects is equivalent to the existence of embedded eigenvalues of the time evolution operator.
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arxiv:1805.11742
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we study the bandwidth and multiplexing capacity of an erbium - doped optical memory for quantum storage purposes. we concentrate on the protocol rose ( revival of a silenced echo ) because it has the largest potential multiplexing capacity. our analysis is applicable to other protocols that involve strong optical excitation. we show that the memory performance is limited by instantaneous spectral diffusion and we describe how this effect can be minimised to achieve optimal performance.
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arxiv:1409.5544
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we study two - loop euler - heisenberg effective actions in three - dimensional n = 2 and n = 4 supersymmetric quantum electrodynamics ( sqed ) without chern - simons term. we find exact expressions for propagators of chiral superfields interacting with slowly - varying n = 2 gauge superfield. using these propagators we compute two - loop effective actions in the n = 2 and n = 4 sqed as the functionals of superfield strengths and their covariant spinor derivatives. the obtained effective actions contain new terms having no four - dimensional analogs. as an application, we find two - loop quantum corrections to the moduli space metric in the n = 2 sqed.
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arxiv:1305.4815
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we prove a quantitative equidistribution statement for adelic homogeneous subsets whose stabilizer is maximal and semisimple. fixing the ambient space, the statement is uniform in all parameters. we explain how this implies certain equidistribution theorems which, even in a qualitative form, are not accessible to measure - classification theorems. as another application, we describe another proof of property tau for arithmetic groups.
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arxiv:1503.05884
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in this paper, we study the existence of the tangent cone to a positive plurisubharmonic or plurisuperharmonic current with a suitable condition. some estimates of the growth of the lelong functions associated to the current and to its $ dd ^ c $ are given to ensure the existence of the blow - up of this current. a second proof for the existence of the tangent cone is derived from these estimates.
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arxiv:1112.3469
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let $ ( q, r ) $ be a gentle quiver such that $ q $ is a directed tree, and $ \ mathbb { k } $ be an algebraically closed field. we study the resolving subcategories generated by a single nonprojective indecomposable module of $ \ mathbb { k } q / \ langle r \ rangle $ - mod. we modify the geometric model of baur - - coelho - sim \ ~ oes and opper - - plamondon - - schroll to compute such subcategories. then we prove that these subcategories are the join - irreducible of the poset of all the resolving subcategories ordered by inclusion.
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arxiv:2502.20994
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ultra - high energy ( uhe ) photons play an important role as an independent probe of the photo - pion production mechanism by uhe cosmic rays. their observation, or non - observation, may constrain astrophysical scenarios for the origin of uhecrs and help to understand the nature of the flux suppression observed by several experiments at energies above $ 10 ^ { 19. 5 } $ ev. whereas the interaction length of uhe photons above $ 10 ^ { 17 } $ ev ranges from a few hundred kpc up to tenths of mpc, photons can interact with the extragalactic background radiation initiating the development of electromagnetic cascades which affect the fluxes of photons observed at earth. the interpretation of the current experimental results rely on the simulations of the uhe photon propagation. in this paper, we present the novel monte carlo code eleca to simulate the $ ele $ ctromagnetic $ ca $ scading initiated by high - energy photons and electrons. we provide an estimation of the surviving probability for photons inducing electromagnetic cascades as a function of their distance from the observer and we calculate the distances within which we expect to observe uhe photons with energy between $ 10 ^ { 17 } $ and $ 10 ^ { 19 } $ ev. furthermore, the flux of gzk photons at earth is investigated in several astrophysical scenarios where we vary both injection spectrum and composition at the source and the intensity of the intervening extragalactic magnetic field. although the photon propagation depends on several astrophysical factors, our numerical predictions combined with future experimental observations ( or non - observations ) of uhe photons - - in the energy range between $ 10 ^ { 17. 5 } $ ev and $ 10 ^ { 20 } $ ev - - can help to constrain these scenarios.
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arxiv:1311.6140
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motivated by recent works in the communication and psychology literature, we model and study the role social identity - - a person ' s sense of belonging to a group - - plays in human information consumption. a hallmark of social identity theory ( sit ) is the notion of ' status ', i. e., an individual ' s desire to enhance their and their ' in - group ' s ' utility relative to that of an ' out - group '. in the context of belief formation, this comes off as a desire to believe positive news about the in - group and negative news about the out - group, which has been empirically shown to support belief in misinformation and false news. we model this phenomenon as a stackelberg game being played over an information channel between a news - source ( sender ) and news - consumer ( receiver ), with the receiver incorporating the ' status ' associated with social identity in their utility, in addition to accuracy. we characterize the strategy that must be employed by the sender to ensure that its message is trusted by receivers of all identities while maximizing their overall quality of information. we show that, as a rule, this optimal quality of information at equilibrium decreases when a receiver ' s sense of identity increases. we further demonstrate how extensions of our model can be used to quantitatively estimate the level of importance given to identity in a population.
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arxiv:2203.16660
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patch - based adversarial attacks introduce a perceptible but localized change to the input that induces misclassification. while progress has been made in defending against imperceptible attacks, it remains unclear how patch - based attacks can be resisted. in this work, we study two different approaches for defending against black - box patch attacks. first, we show that adversarial training, which is successful against imperceptible attacks, has limited effectiveness against state - of - the - art location - optimized patch attacks. second, we find that compositional deep networks, which have part - based representations that lead to innate robustness to natural occlusion, are robust to patch attacks on pascal3d + and the german traffic sign recognition benchmark, without adversarial training. moreover, the robustness of compositional models outperforms that of adversarially trained standard models by a large margin. however, on gtsrb, we observe that they have problems discriminating between similar traffic signs with fine - grained differences. we overcome this limitation by introducing part - based finetuning, which improves fine - grained recognition. by leveraging compositional representations, this is the first work that defends against black - box patch attacks without expensive adversarial training. this defense is more robust than adversarial training and more interpretable because it can locate and ignore adversarial patches.
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arxiv:2012.00558
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biomedical research often produces high - dimensional data confounded by batch effects such as systematic experimental variations, different protocols and subject identifiers. without proper correction, low - dimensional representation of high - dimensional data might encode and reproduce the same systematic variations observed in the original data, and compromise the interpretation of the results. in this article, we propose a novel procedure to remove batch effects from low - dimensional embeddings obtained with t - sne dimensionality reduction. the proposed methods are based on linear algebra and constrained optimization, leading to efficient algorithms and fast computation in many high - dimensional settings. results on artificial single - cell transcription profiling data show that the proposed procedure successfully removes multiple batch effects from t - sne embeddings, while retaining fundamental information on cell types. when applied to single - cell gene expression data to investigate mouse medulloblastoma, the proposed method successfully removes batches related with mice identifiers and the date of the experiment, while preserving clusters of oligodendrocytes, astrocytes, and endothelial cells and microglia, which are expected to lie in the stroma within or adjacent to the tumors.
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arxiv:1911.06708
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let $ t $ be the extinction moment of a critical branching process $ z = ( z _ { n }, n \ geq 0 ) $ in a random environment specified by iid probability generating functions. we study the asymptotic behavior of the probability of extinction of the process $ z $ at moment $ n \ to \ infty $, and show that if the logarithm of the ( random ) expectation of the offspring number belongs to the domain of attraction of a non - gaussian stable law then the extinction occurs owing to very unfavorable environment forcing the process, having at moment $ t - 1 $ exponentially large population, to die out. we also give an interpretation of the obtained results in terms of random walks in random environment.
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arxiv:0809.0986
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over a complete riemannian manifold of finite dimension, greene and wu introduced a convolution, known as greene - wu ( gw ) convolution. in this paper, we study properties of the gw convolution and apply it to non - euclidean machine learning problems. in particular, we derive a new formula for how the curvature of the space would affect the curvature of the function through the gw convolution. also, following the study of the gw convolution, a new method for gradient estimation over riemannian manifolds is introduced.
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arxiv:2108.07406
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this paper addresses the issue of integrating agents with a variety of external resources and services, as found in enterprise computing environments. we propose an approach for interfacing agents and existing message routing and mediation engines based on the endpoint concept from the enterprise integration patterns of hohpe and woolf. a design for agent endpoints is presented, and an architecture for connecting the jason agent platform to the apache camel enterprise integration framework using this type of endpoint is described. the approach is illustrated by means of a business process use case, and a number of camel routes are presented. these demonstrate the benefits of interfacing agents to external services via a specialised message routing tool that supports enterprise integration patterns.
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arxiv:1302.1937
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the secrecy of a communication system in which both the legitimate receiver and an eavesdropper are allowed some distortion is investigated. the secrecy metric considered is the exponent of the probability that the eavesdropper estimates the source sequence successfully within an acceptable distortion level. the problem is first studied when the transmitter and the legitimate receiver do not share any key and the transmitter is not subject to a rate constraint, which corresponds to a stylized model of a side channel and reveals connections to source coding with side information. the setting is then generalized to include a shared secret key between the transmitter and the legitimate receiver and a rate constraint on the transmitter, which corresponds to the shannon cipher system. a single - letter characterization of the highest achievable exponent is provided, and asymptotically - optimal strategies for both the primary user and the eavesdropper are demonstrated.
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arxiv:1507.02342
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we present an unsupervised model for inducing signed social networks from the content exchanged across network edges. inference in this model solves three problems simultaneously : ( 1 ) identifying the sign of each edge ; ( 2 ) characterizing the distribution over content for each edge type ; ( 3 ) estimating weights for triadic features that map to theoretical models such as structural balance. we apply this model to the problem of inducing the social function of address terms, such as ' madame ', ' comrade ', and ' dude '. on a dataset of movie scripts, our system obtains a coherent clustering of address terms, while at the same time making intuitively plausible judgments of the formality of social relations in each film. as an additional contribution, we provide a bootstrapping technique for identifying and tagging address terms in dialogue.
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arxiv:1411.4351
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we briefly review the basics ideas and results of a recently proposed statistical mechanical approach to granular materials. using lattice models from standard statistical mechanics and results from a mean field replica approach and monte carlo simulations we find a jamming transition in granular media closely related to the glass transition in super - cooled liquids. these models reproduce the logarithmic relaxation in granular compaction and reversible - irreversible lines, in agreement with experimental data. the models also exhibit aging effects and breakdown of the usual fluctuation dissipation relation. it is shown that the glass transition may be responsible for the logarithmic relaxation and may be related to the cooperative effects underlying many phenomena of granular materials such as the reynolds transition.
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arxiv:cond-mat/0001362
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in this article we continue the author ' s investigation of the m \ " obius - invariant willmore flow moving parametrizations of umbilic - free tori in $ \ mathbb { r } ^ n $ and in the $ n $ - sphere $ \ mathbb { s } ^ n $. in the main theorems of this article we prove basic properties of the evolution operator of the " deturck modification " of the m \ " obius - invariant willmore flow and of its fr \ ' echet derivative by means of a combination of the author ' s results about this topic with the theory of " bounded $ \ mathcal { h } _ { \ infty } $ - calculus " for linear elliptic operators due to amann, denk, duong, hieber, pr \ " uss and simonett, and with amann ' s and lunardi ' s work on semigroups and interpolation theory. precisely, we prove local real analyticity of the evolution operator $ [ f \ mapsto \ mathcal { p } ^ * ( \, \ cdot \,, 0, f ) ] $ of the " deturck modification " of the m \ " obius - invariant willmore flow in a small open ball in $ w ^ { 4 - \ frac { 4 } { p }, p } ( \ sigma, \ mathbb { r } ^ n ) $, for any $ p \ in ( 3, \ infty ) $, about any fixed smooth parametrization $ f _ 0 : \ sigma \ longrightarrow \ mathbb { r } ^ n $ of a compact and umbilic - free torus in $ \ mathbb { r } ^ n $. we prove moreover that the entire maximal flow line $ \ mathcal { p } ^ * ( \, \ cdot \,, 0, f _ 0 ) $, starting to move in a smooth and umbilic - free initial immersion $ f _ 0 $, is real analytic for positive times, and that therefore the fr \ ' echet derivative $ d _ { f } \ mathcal { p } ^ * ( \, \ cdot \,, 0, f _ 0 ) $ of the evolution operator in $ f _ 0 $ can be uniquely extended to a family of continuous linear operators $ g ^ { f _ 0 } ( t _ 2, t _ 1 ) $ in $ l ^ p ( \ sigma,
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arxiv:2011.03832
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proteinaceous aggregation occurs through self - assembly - - a process not entirely understood. in a recent article [ 1 ], an analytical theory for amyloid fibril growth via secondary rather than primary nucleation was presented. remarkably, with only a single kinetic parameter, the authors were able to unify growth characteristics for a variety of experimental data. in essence, they seem to have uncovered the underlying allometric laws governing the evolution of filament elongation simply from two coupled non - linear ordinary differential equations ( odes ) stemming from a master equation. while this work adds significantly to our understanding of filament self - assembly, it required an approximate analytical solution representation. here, we show that the same results are found by purely numerical means once a straightforward and reliable numerical solution to the set of odes has been established.
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arxiv:1006.3022
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this paper proposes a decentralized recommender system by formulating the popular collaborative filleting ( cf ) model into a decentralized matrix completion form over a set of users. in such a way, data storages and computations are fully distributed. each user could exchange limited information with its local neighborhood, and thus it avoids the centralized fusion. advantages of the proposed system include a protection on user privacy, as well as better scalability and robustness. we compare our proposed algorithm with several state - of - the - art algorithms on the flickeruserfavor dataset, and demonstrate that the decentralized algorithm can gain a competitive performance to others.
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arxiv:1503.01647
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we study the impact of topological phase transitions of the internal calabi - yau threefold on the space - time geometry of five - dimensional extremal black holes and black strings. for flop transitions and su ( 2 ) gauge symmetry enhancement we show that solutions can always be continued and that the behaviour of metric, gauge fields and scalars can be characterized in a model independent way. then we look at supersymmetric solutions which describe naked singularities rather than geometries with a horizon. for black strings we show that the solution cannot become singular as long as the scalar fields take values inside the kahler cone. for black holes we establish the same result for the elliptic fibrations over the hirzebruch surfaces f _ 0, f _ 1, f _ 2. these three models exhibit a behaviour similar to the enhancon, since one runs into su ( 2 ) enhancement before reaching the apparent singularity. using the proper continuation inside the enhancon radius one finds that the solution is regular.
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arxiv:hep-th/0212200
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in this study, we revisit and complete the full next - to - leading order corrections to pseudoscalar double - dalitz decays within the soft - photon approximation. comparing to the previous study, we find small differences, which are nevertheless relevant for extracting information about the pseudoscalar transition form factors. concerning the latter, these processes could offer the opportunity to test them - for the first time - in their double - virtual regime
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arxiv:1801.06067
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probabilistic power flow ( ppf ) analysis is critical to power system operation and planning. ppf aims at obtaining probabilistic descriptions of the state of the system with stochastic power injections ( e. g., renewable power generation and load demands ). given power injection samples, numerical methods repeatedly run classic power flow ( pf ) solvers to find the voltage phasors. however, the computational burden is heavy due to many pf simulations. recently, many data - driven based pf solvers have been proposed due to the availability of sufficient measurements. this paper proposes a novel neural network ( nn ) framework which can accurately approximate the non - linear ac - pf equations. the trained nn works as a rapid pf solver, significantly reducing the heavy computational burden in classic ppf analysis. inspired by residual learning, we develop a fully connected linear layer between the input and output in the multilayer perceptron ( mlp ). to improve the nn training convergence, we propose three schemes to initialize the nn weights of the shortcut connection layer based on the physical characteristics of ac - pf equations. specifically, two model - based methods require the knowledge of system topology and line parameters, while the purely data - driven method can work without power grid parameters. numerical tests on five benchmark systems show that our proposed approaches achieve higher accuracy in estimating voltage phasors than existing methods. in addition, three meticulously designed initialization schemes help the nn training process converge faster, which is appealing under limited training time.
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arxiv:2301.12062
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cluster validity indexes are very important tools designed for two purposes : comparing the performance of clustering algorithms and determining the number of clusters that best fits the data. these indexes are in general constructed by combining a measure of compactness and a measure of separation. a classical measure of compactness is the variance. as for separation, the distance between cluster centers is used. however, such a distance does not always reflect the quality of the partition between clusters and sometimes gives misleading results. in this paper, we propose a new cluster validity index for which jeffrey divergence is used to measure separation between clusters. experimental results are conducted using different types of data and comparison with widely used cluster validity indexes demonstrates the outperformance of the proposed index.
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arxiv:1812.08891
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we consider the estimation of the policy gradient in partially observable markov decision processes ( pomdp ) with a special class of structured policies that are finite - state controllers. we show that the gradient estimation can be done in the actor - critic framework, by making the critic compute a " value " function that does not depend on the states of pomdp. this function is the conditional mean of the true value function that depends on the states. we show that the critic can be implemented using temporal difference ( td ) methods with linear function approximations, and the analytical results on td and actor - critic can be transfered to this case. although actor - critic algorithms have been used extensively in markov decision processes ( mdp ), up to now they have not been proposed for pomdp as an alternative to the earlier proposal gpomdp algorithm, an actor - only method. furthermore, we show that the same idea applies to semi - markov problems with a subset of finite - state controllers.
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arxiv:1207.1421
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our star - count analysis of the two micron all sky survey point sources resulted in an identification of the star cluster g144. 9 + 0. 4. the cluster was found, but not characterized, by glushkova et al. we show that the cluster is physically associated with the cam ob1 association at a distance of about 1 kpc and with an age of 1 - 2 myr. pre - main sequence stars are identified on the basis of photometric and proper motion data. a total of 91 additional ob star candidates was found in subgroups 1a and 1b, a significant increase from the currently known 43 ob stars. the ob members show an age spread that indicates a sustained star formation for at least the last 10 - 15 myr. the young cluster g144. 9 + 0. 4 represents the latest episode of sequential star formation in this cloud complex.
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arxiv:1308.6162
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unauthorized privacy - related and copyrighted content generation using generative - ai is becoming a significant concern for human society, raising ethical, legal, and privacy issues that demand urgent attention. the eu ' s general data protection regulation ( gdpr ) include a " right to be forgotten, " which allows individuals to request the deletion of their personal data. however, this primarily applies to data stored in traditional databases, not ai models. recently, machine unlearning techniques have arise that attempt to eliminate the influence of sensitive content used during ai model training, but they often require extensive updates to the deployed systems and incur substantial computational costs. in this work, we propose a novel and efficient method called single layer unlearning gradient ( slug ), that can unlearn targeted information by updating targeted layers of a model using a one - time gradient computation. our method is highly modular and enables the selective removal of multiple sensitive concepts, such as celebrity names and copyrighted content, from the generated outputs of widely used foundation models ( e. g., clip ) and generative models ( e. g., stable diffusion ). broadly, our method ensures ai - generated content complies with privacy regulations and intellectual property laws, fostering responsible use of generative models, mitigating legal risks and promoting a trustworthy, socially responsible ai ecosystem.
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arxiv:2407.11867
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subject : in this article, convolutional networks of one, two, and three dimensions are compared with respect to their ability to distinguish between the drawing tests produced by parkinson ' s disease patients and healthy control subjects. motivation : the application of deep learning techniques for the analysis of drawing tests to support the diagnosis of parkinson ' s disease has become a growing trend in the area of artificial intelligence. method : the dynamic features of the handwriting signal are embedded in the static test data to generate one - dimensional time series, two - dimensional rgb images and three - dimensional voxelized point clouds, and then one -, two -, and three - dimensional cnn can be used to automatically extract features for effective diagnosis. novelty : while there are many results that describe the application of two - dimensional convolutional models to the problem, to the best knowledge of the authors, there are no results based on the application of three - dimensional models and very few using one - dimensional models. main result : the accuracy of the one -, two - and three - dimensional cnn models was 62. 50 %, 77. 78 % and 83. 34 % in the drawritepd dataset ( acquired by the authors ) and 73. 33 %, 80. 00 % and 86. 67 % in the pahaw dataset ( well known from the literature ), respectively. for these two data sets, the proposed three - dimensional convolutional classification method exhibits the best diagnostic performance.
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arxiv:2309.14288
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we study the layer of electrons on bare strange star surfaces, taking the dirac exchange - energy into account. because electrons are fermions, the electron wave function must be of exchange - antisymmetry. the dirac exchange - energy originates, consequently, from the exchange - antisymmetry of electron wave functions. this consideration may result in changing the electron distribution and the electric field on the surface of bare strange star. the strong magnetic field effect on the structures of the electrospheres is also discussed.
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arxiv:0712.2650
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the yolo ( you only look once ) series has been a leading framework in real - time object detection, consistently improving the balance between speed and accuracy. however, integrating attention mechanisms into yolo has been challenging due to their high computational overhead. yolov12 introduces a novel approach that successfully incorporates attention - based enhancements while preserving real - time performance. this paper provides a comprehensive review of yolov12 ' s architectural innovations, including area attention for computationally efficient self - attention, residual efficient layer aggregation networks for improved feature aggregation, and flashattention for optimized memory access. additionally, we benchmark yolov12 against prior yolo versions and competing object detectors, analyzing its improvements in accuracy, inference speed, and computational efficiency. through this analysis, we demonstrate how yolov12 advances real - time object detection by refining the latency - accuracy trade - off and optimizing computational resources.
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arxiv:2504.11995
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we define a plane curve to be threadable if it can rigidly pass through a point - hole in a line l without otherwise touching l. threadable curves are in a sense generalizations of monotone curves. we have two main results. the first is a linear - time algorithm for deciding whether a polygonal curve is threadable - - - o ( n ) for a curve of n vertices - - - and if threadable, finding a sequence of rigid motions to thread it through a hole. we also sketch an argument that shows that the threadability of algebraic curves can be decided in time polynomial in the degree of the curve. the second main result is an o ( n polylog n ) - time algorithm for deciding whether a 3d polygonal curve can thread through hole in a plane in r ^ 3, and if so, providing a description of the rigid motions that achieve the threading.
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arxiv:1801.08003
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internet of things ( iot ) is one of main paradigms for 5g wireless systems. due to high connection density, interference from other sources is a key problem in iot networks. especially, it is more difficult to find a solution to manage interference in uncoordinated networks than coordinated system. in this work, we consider 3d topology of uncoordinated iot network and propose interference mitigation scheme with respect to 3d antenna radiation pattern. in 2d topology network, the radiation pattern of dipole antenna can be assumed as onmi - directional. we show the variance of antenna gain on dipole antenna in 3d topology, consider the simultaneous use of three orthogonal dipole antennas, and compare the system performance depending on different antenna configurations. our simulation results show that proper altitude of iot devices can extensively improve the system performance.
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arxiv:1909.06655
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using the description of the subprocess $ \ gamma \ gamma ^ * \ to s ( p ) $ in terms of local nambu - jona - lasinio model we calculate the cross sections of photoproduction of scalar and pseudoscalar mesons in high energy photon - lepton collisions processes. the dependence on the transversal momentum and the total cross sections in weizsaecker - williams approximation are presented.
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arxiv:0902.1384
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we investigate the angular distribution of satellite galaxies in and around pairs of galaxy groups in sdss and compare the results with the satellite distribution in pairs of dark matter halos by constructing mock catalogs that account for the same selection effects as the observational sample. we find that the angular distribution of satellites in both sdss and the mock catalog exhibits a pronounced tendency towards lopsidedness, with satellites preferentially located between the two central galaxies. additionally, there is a significant bulging distribution characterized by a higher concentration of satellites along the line connecting the two centrals compared to those found perpendicular to it. the lopsided and bulging distributions strengthen as pair separation and halo mass increase. the mock catalog successfully reproduces the observational results across all cases considered. we find that the lopsided and bulging distribution of satellites can largely be explained by overlapping two randomly selected halos matched in mass to the actual halo pairs, along with their surrounding satellite distribution, provided that the alignment between the orientations of the halos and the line connecting the halo pairs is taken into account. this suggests that the angular distribution of satellites is a natural consequence of the formation and evolution of large - scale structure in a $ \ lambda $ cdm universe, eliminating the need to introduce other physical origins.
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arxiv:2502.14666
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we present 645 optical spectra of 73 supernovae ( sne ) of types iib, ib, ic, and broad - lined ic. all of these types are attributed to the core collapse of massive stars, with varying degrees of intact h and he envelopes before explosion. the sne in our sample have a mean redshift < cz > = 4200 km / s. most of these spectra were gathered at the harvard - smithsonian center for astrophysics ( cfa ) between 2004 and 2009. for 53 sne, these are the first published spectra. the data coverage range from mere identification ( 1 - 3 spectra ) for a few sne to extensive series of observations ( 10 - 30 spectra ) that trace the spectral evolution for others, with an average of 9 spectra per sn. for 44 sne of the 73 sne presented here, we have well - determined dates of maximum light to determine the phase of each spectrum. our sample constitutes the most extensive spectral library of stripped - envelope sne to date. we provide very early coverage ( as early as 30 days before v - band max ) for photospheric spectra, as well as late - time nebular coverage when the innermost regions of the sne are visible ( as late as 2 years after explosion, while for sn1993j, we have data as late as 11. 6 years ). this data set has homogeneous observations and reductions that allow us to study the spectroscopic diversity of these classes of stripped sne and to compare these to sne associated with gamma - ray bursts. we undertake these matters in follow - up papers.
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arxiv:1405.1910
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genomic discoveries to personalised medicine involves some major scientific, logistical and regulatory hurdles. this includes patient consent, sample acquisition, clinical annotation and study design, all of which can lead to data generation and computational analyses. additionally, functional and mechanistic studies remain a challenge, which can lead to drug and biomarker discovery and development, commercial challenges and genomics - informed clinical trials. importantly, these key scientific challenges are interdependent with each other. directed and streamlined approaches are sought to be developed for a rapid generation of biological discoveries, which can allow for cancer genomic discoveries to translate to the clinic. delivering personalised cancer medicine benefits from traditional, unconstrained and non - directed academic exploration, with the goal of directing scientific inquiry to convert genomic discovery to diagnostic and therapeutic targets. = = = proteomics = = = another example of discovery science is proteomics, a technology - driven and technology limited discovery science. technologies for proteomic analysis provide information that is useful in discovery science. proteome analysis as a discovery science is applicable in biotechnology, e. g., it assists in 1 ) the discovery of biochemical pathways which can identify targets for therapies, 2 ) developing new processes for manufacturing biological materials, 3 ) monitoring manufacturing processes for the purpose of quality control, and 4 ) developing diagnostic tests and efficacious treatment strategies for clinical diseases. in the context of proteomics, current life - science research remains technology - limited, however, recent available tools have assisted in evolving such research from being hypothesis - driven to discovery - driven. = = = hydrology = = = field hydrology has experienced a decline in progress due to a change from discovery - based field work to the gathering of data for modal parameterisation. in field hydrology, models are not any more useful than an understanding of how systems work, and discovery science allows for this understanding. several important examples of field - based inquiry and discovery have taken place in field hydrology. these include : identifying spatial patterns of soil moisture and how they relate to topography ; interrogating such data through the use of geostatistics ; and discovering the importance of macropore flow and hydrological connectivity. some discovery - based questions that have been asked in field hydrology include 1 ) determining which parts of the watershed are most important in determining water delivery to the channel, 2 ) how the presence of ' old ' water can be explained by groundwater travelling into the stream, and 3 ) how there can be an explanation
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https://en.wikipedia.org/wiki/Discovery_science
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the coefficients determining the dilepton decay angular distribution of vector particles obey certain positivity constraints and a rotation - invariant identity. these relations are a direct consequence of the covariance properties of angular momentum eigenstates and are independent of the production mechanism. the lam - tung relation can be derived as a particular case, simply recognizing that the drell - yan dilepton is always produced transversely polarized with respect to one or more quantization axes. the dilepton angular distribution continues to be characterized by a frame - independent identity also when the lam - tung relation is violated. moreover, the violation can be easily characterized by measuring a one - dimensional distribution depending on one shape coefficient.
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arxiv:1102.3946
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part of the maps special issue of the astrophysical journal supplement.
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arxiv:2109.06419
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this is a historical note. in 1981 we constructed a discrete version of quantum nonlinear schroedinger equation. this led to our discovery of quantum determinant : it appeared in construction of anti - pod ( 11 ). later these became important in quantum groups : it describes the center of yang - baxter algebra. our paper was published in doklady akademii nauk vol 259, page 76 ( july l981 ) in russian language.
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arxiv:0910.0295
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the presence of $ \ alpha $ - clustered structure in the light nuclei produces different exotic shapes in nuclear structure studies at low energies. recent phenomenological studies suggest that collision of heavy nuclei with $ \ alpha $ - clustered carbon ( $ ^ { 12 } $ c ) at relativistic energies can lead to large initial state anisotropies. this is expected to impact the final momentum anisotropies of the produced particles significantly. the emission of electromagnetic radiations is considered to be more sensitive to the initial state compared to hadronic observables and thus photon observables are expected to be affected by the initial clustered structure profoundly. in this work we estimate the production and anisotropic flow of photons from most - central collisions of triangular $ \ alpha $ - clustered carbon and gold at $ \ sqrt { s _ { \ rm nn } } = 200 $ gev using an event - by - event hydrodynamic framework and compare the results with those obtained from unclustered carbon and gold collisions. we show that the thermal photon $ v _ 3 $ for most central collisions is significantly large for the clustered case compared to the case with unclustered carbon, whereas the elliptic flow parameter does not show much difference for the two cases. in addition, the ratio of anisotropic flow coefficients is found to be a potential observable to constrain the initial state produced in relativistic heavy - ion collisions and also to know more about the $ \ alpha $ - clustered structure in carbon nucleus.
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arxiv:2204.00235
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artificial neural networks ( anns ) have shown to be amongst the most important artificial intelligence ( ai ) techniques in educational applications, providing adaptive educational services. however, their educational potential is limited in practice due to three major challenges : i ) difficulty in incorporating symbolic educational knowledge ( e. g., causal relationships, and practitioners ' knowledge ) in their development, ii ) learning and reflecting biases, and iii ) lack of interpretability. given the high - risk nature of education, the integration of educational knowledge into anns becomes crucial for developing ai applications that adhere to essential educational restrictions, and provide interpretability over the predictions. this research argues that the neural - symbolic family of ai has the potential to address the named challenges. to this end, it adapts a neural - symbolic ai framework and accordingly develops an approach called nsai, that injects and extracts educational knowledge into and from deep neural networks, for modelling learners computational thinking. our findings reveal that the nsai approach has better generalizability compared to deep neural networks trained merely on training data, as well as training data augmented by smote and autoencoder methods. more importantly, unlike the other models, the nsai approach prioritises robust representations that capture causal relationships between input features and output labels, ensuring safety in learning to avoid spurious correlations and control biases in training data. furthermore, the nsai approach enables the extraction of rules from the learned network, facilitating interpretation and reasoning about the path to predictions, as well as refining the initial educational knowledge. these findings imply that neural - symbolic ai can overcome the limitations of anns in education, enabling trustworthy and interpretable applications.
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arxiv:2311.00393
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in this paper, we study linear codes over $ \ mathbb { z } _ k $ based on lattices and theta functions. we obtain the complete weight enumerators macwilliams identity and the symmetrized weight enumerators macwilliams identity based on the theory of theta function. we extend the main work by bannai, dougherty, harada and oura to the finite ring $ \ mathbb { z } _ k $ for any positive integer $ k $ and present the complete weight enumerators macwilliams identity in genus $ g $. when $ k = p $ is a prime number, we establish the relationship between the theta function of associated lattices over a cyclotomic field and the complete weight enumerators with hamming weight of codes, which is an analogy of the results by g. van der geer and f. hirzebruch since they showed the identity with the lee weight enumerators.
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arxiv:2504.12604
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larmor ' s theorem holds for magnetic systems that are invariant under spin rotation. in the presence of spin - orbit coupling this invariance is lost and larmor ' s theorem is broken : for systems of interacting electrons, this gives rise to a subtle interplay between the spin - orbit coupling acting on individual single - particle states and coulomb many - body effects. we consider a quasi - two - dimensional, partially spin - polarized electron gas in a semiconductor quantum well in the presence of rashba and dresselhaus spin - orbit coupling. using a linear - response approach based on time - dependent density - functional theory, we calculate the dispersions of spin - flip waves. we obtain analytic results for small wave vectors and up to second order in the rashba and dresselhaus coupling strengths $ \ alpha $ and $ \ beta $. comparison with experimental data from inelastic light scattering allows us to extract $ \ alpha $ and $ \ beta $ as well as the spin - wave stiffness very accurately. we find significant deviations from the local density approximation for spin - dependent electron systems.
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arxiv:1612.04314
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we consider the multi armed bandit problem in non - stationary environments. based on the bayesian method, we propose a variant of thompson sampling which can be used in both rested and restless bandit scenarios. applying discounting to the parameters of prior distribution, we describe a way to systematically reduce the effect of past observations. further, we derive the exact expression for the probability of picking sub - optimal arms. by increasing the exploitative value of bayes ' samples, we also provide an optimistic version of the algorithm. extensive empirical analysis is conducted under various scenarios to validate the utility of proposed algorithms. a comparison study with various state - of - the - arm algorithms is also included.
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arxiv:1707.09727
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in this paper we propose scdp, a general - purpose data transport protocol for data centres that, in contrast to all other protocols proposed to date, supports efficient one - to - many and many - to - one communication, which is extremely common in modern data centres. scdp does so without compromising on efficiency for short and long unicast flows. scdp achieves this by integrating raptorq codes with receiver - driven data transport, packet trimming and multi - level feedback queuing ( mlfq ) ; ( 1 ) raptorq codes enable efficient one - to - many and many - to - one data transport ; ( 2 ) on top of raptorq codes, receiver - driven flow control, in combination with in - network packet trimming, enable efficient usage of network resources as well as multi - path transport and packet spraying for all transport modes. incast and outcast are eliminated ; ( 3 ) the systematic nature of raptorq codes, in combination with mlfq, enable fast, decoding - free completion of short flows. we extensively evaluate scdp in a wide range of simulated scenarios with realistic data centre workloads. for one - to - many and many - to - one transport sessions, scdp performs significantly better compared to ndp and pias. for short and long unicast flows, scdp performs equally well or better compared to ndp and pias.
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arxiv:1909.08928
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the maximum beam current can be accelerated in an energy recovery linac ( erl ) can be severely limited by the transverse multi - pass beam breakup instability ( bbu ), especially in future erl light sources with multi - gev high energy beam energy and more than 100 ma average current. in this paper, the multi - pass bbu of such a high energy erl is studied based on the simulation on a 3 - gev erl light source proposed by kek. it is expected to provide a reference to the future high energy erl projects by this work.
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arxiv:1402.6386
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modern neural networks are undeniably successful. numerous works study how the curvature of loss landscapes can affect the quality of solutions. in this work we study the loss landscape by considering the hessian matrix during network training with large learning rates - an attractive regime that is ( in ) famously unstable. we characterise the instabilities of gradient descent, and we observe the striking phenomena of \ textit { landscape flattening } and \ textit { landscape shift }, both of which are intimately connected to the instabilities of training.
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arxiv:2307.11948
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