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2 f _ { 4, 0, 0, 2 } ( v ) + z ^ 3 \ overline { z } ^ 2 \ overline { \ zeta } f _ { 3, 0, 2, 1 } ( v ) + z ^ 3 \ overline { z } \ overline { \ zeta } ^ 2 f _ { 3, 0, 1, 2 } ( v ) + z ^ 3 { \ overline { \ zeta } } ^ 3 f _ { 3, 0, 0, 3 } ( v ) \ } \ \ & + z ^ 3 \ overline { z } ^ 3 { \ rm o } _ { z, \ overline { z } } ( 1 ) + 2 { \ rm re } ( \ overline { z } ^ 3 \ zeta { \ rm o } _ { z, \ zeta, \ overline { z } } ( 3 ) ) + \ zeta \ overline { \ zeta } \, { \ rm o } _ { z, \ zeta, \ overline { z }, \ overline { \ zeta } } ( 5 ). \ end { align } the values at the origin of pocchiola ' s two primary invariants are : \ [ w _ 0 = 4 \ overline { f _ { 3, 0, 0, 2 } ( 0 ) }, \ quad \ quad j _ 0 = 20 \, f _ { 5, 0, 0, 1 } ( 0 ). \ ] the proofs are detailed, accessible to non - experts. the computer - generated aspects ( upcoming ) have been reduced to a minimum. | arxiv:2003.01952 |
convolutional neural networks ( cnns ) are the state - of - the - art technique for identifying strong gravitational lenses. although they are highly successful in recovering genuine lens systems with a high true - positive rate, the unbalanced nature of the data set ( lens systems are rare ), still leads to a high false positive rate. for these techniques to be successful in upcoming surveys ( e. g. with euclid ) most emphasis should be set on reducing false positives, rather than on reducing false negatives. in this paper, we introduce densely connected neural networks ( densenets ) as the cnn architecture in a new pipeline - ensemble model containing an ensemble of classification cnns and regression cnns to classify and rank - order lenses, respectively. we show that densenets achieve comparable true positive rates but considerably lower false positive rates ( when compared to residual networks ; resnets ). thus, we recommend densenets for future missions involving large data sets, such as euclid, where low false positive rates play a key role in the automated follow - up and analysis of large numbers of strong gravitational lens candidates when human vetting is no longer feasible | arxiv:2311.08184 |
let $ g $ be a compact lie group. suppose $ g _ 1, \ dots, g _ k $ are chosen independently from the haar measure on $ g $. let $ \ mathcal { a } = \ cup _ { i \ in [ k ] } \ mathcal { a } _ i $, where, $ \ mathcal { a } _ i : = \ { g _ i \ } \ cup \ { g _ i ^ { - 1 } \ } $. let $ \ mu _ { \ mathcal { a } } ^ \ ell $ be the uniform measure over all words of length $ \ ell $ whose alphabets belong to $ \ mathcal { a } $. we give probabilistic bounds on the nearness of a heat kernel smoothening of $ \ mu _ { \ mathcal { a } } ^ \ ell $ to a constant function on $ g $ in $ \ mathcal { l } ^ 2 ( g ) $. we also give probabilistic bounds on the maximum distance of a point in $ g $ to the support of $ \ mu _ { \ mathcal { a } } ^ \ ell $. lastly, we show that these bounds cannot in general be significantly improved by analyzing the case when $ g $ is the $ n - $ dimensional torus. the question of a spectral gap of a natural markov operator associated with $ \ mathcal { a } $ when $ g $ is $ su _ 2 $ was reiterated by bourgain and gamburd, being first raised by lubotzky, philips and sarnak in 1987 and is still open. in the setting of $ su _ 2 $, our results can be viewed as addressing a quantitative version of a weak variant of this question. | arxiv:1804.07146 |
this paper is dedicated to the construction of multidimensional spherical monogenics. firstly, we investigate the construction of monogenic functions in dimension $ 3 $ by applying the dirac operator to the orthonormal bases of spherical harmonics, resulting in orthogonal spherical monogenics. additionally, we employ the reproducing kernel for monogenic functions and a specialized optimization method to derive various types of $ 3 $ - dimensional spherical harmonics and spherical monogenics. | arxiv:2406.04863 |
this note provides a matlab code to determine the critical strain associated with the onset of dynamic recrystallization. the code takes a closed - form constitutive model and derives the critical strain by solving $ \ partial ^ 2 \ theta / \ partial \ sigma ^ 2 = 0 $. moreover, several models that could be used for this purpose are studied. | arxiv:2310.19551 |
we extend the work of hahn and carvalho ( 2015 ) and develop a doubly - regularized sparse regression estimator by synthesizing bayesian regularization with penalized least squares within a decision - theoretic framework. in contrast to existing bayesian decision - theoretic formulation chiefly reliant upon the symmetric 0 - 1 loss, the new method - - which we call bayesian decoupling - - employs a family of penalized loss functions indexed by a sparsity - tuning parameter. we propose a class of reweighted l1 penalties, with two specific instances that achieve simultaneous bias reduction and convexity. the design of the penalties incorporates considerations of signal sizes, as enabled by the bayesian paradigm. the tuning parameter is selected using a posterior benchmarking criterion, which quantifies the drop in predictive power relative to the posterior mean which is the optimal bayes estimator under the squared error loss. additionally, in contrast to the widely used median probability model technique which selects variables by thresholding posterior inclusion probabilities at the fixed threshold of 1 / 2, bayesian decoupling enables the use of a data - driven threshold which automatically adapts to estimated signal sizes and offers far better performance in high - dimensional settings with highly correlated predictors. our numerical results in such settings show that certain combinations of priors and loss functions significantly improve the solution path compared to existing methods, prioritizing true signals early along the path before false signals are selected. consequently, bayesian decoupling produces estimates with better prediction and selection performance. finally, a real data application illustrates the practical advantages of our approaches which select sparser models with larger coefficient estimates. | arxiv:2502.00126 |
the full set of stationary states of the mean field of a bose - einstein condensate in the presence of a potential step or point - like impurity are presented in closed analytic form. the nonlinear schr \ " odinger equation in one dimension is taken as a model. the nonlinear analogs of the continuum of stationary scattering states, as well as evanescent waves, are discussed. the solutions include asymmetric soliton trains and other wavefunctions of novel form, such as a pair of dark solitons bound by an impurity. | arxiv:cond-mat/0410345 |
missing information is a common issue of dialogue summarization where some information in the reference summaries is not covered in the generated summaries. to address this issue, we propose to utilize natural language inference ( nli ) models to improve coverage while avoiding introducing factual inconsistencies. specifically, we use nli to compute fine - grained training signals to encourage the model to generate content in the reference summaries that have not been covered, as well as to distinguish between factually consistent and inconsistent generated sentences. experiments on the dialogsum and samsum datasets confirm the effectiveness of the proposed approach in balancing coverage and faithfulness, validated with automatic metrics and human evaluations. additionally, we compute the correlation between commonly used automatic metrics with human judgments in terms of three different dimensions regarding coverage and factual consistency to provide insight into the most suitable metric for evaluating dialogue summaries. | arxiv:2301.10483 |
humans have remarkable capacity to reason abductively and hypothesize about what lies beyond the literal content of an image. by identifying concrete visual clues scattered throughout a scene, we almost can ' t help but draw probable inferences beyond the literal scene based on our everyday experience and knowledge about the world. for example, if we see a " 20 mph " sign alongside a road, we might assume the street sits in a residential area ( rather than on a highway ), even if no houses are pictured. can machines perform similar visual reasoning? we present sherlock, an annotated corpus of 103k images for testing machine capacity for abductive reasoning beyond literal image contents. we adopt a free - viewing paradigm : participants first observe and identify salient clues within images ( e. g., objects, actions ) and then provide a plausible inference about the scene, given the clue. in total, we collect 363k ( clue, inference ) pairs, which form a first - of - its - kind abductive visual reasoning dataset. using our corpus, we test three complementary axes of abductive reasoning. we evaluate the capacity of models to : i ) retrieve relevant inferences from a large candidate corpus ; ii ) localize evidence for inferences via bounding boxes, and iii ) compare plausible inferences to match human judgments on a newly - collected diagnostic corpus of 19k likert - scale judgments. while we find that fine - tuning clip - rn50x64 with a multitask objective outperforms strong baselines, significant headroom exists between model performance and human agreement. data, models, and leaderboard available at http : / / visualabduction. com / | arxiv:2202.04800 |
this paper studies the quantum computational complexity of the discrete logarithm ( dl ) and related group - theoretic problems in the context of generic algorithms - - that is, algorithms that do not exploit any properties of the group encoding. we establish a generic model of quantum computation for group - theoretic problems, which we call the quantum generic group model. shor ' s algorithm for the dl problem and related algorithms can be described in this model. we show the quantum complexity lower bounds and almost matching algorithms of the dl and related problems in this model. more precisely, we prove the following results for a cyclic group $ g $ of prime order. - any generic quantum dl algorithm must make $ \ omega ( \ log | g | ) $ depth of group operations. this shows that shor ' s algorithm is asymptotically optimal among the generic quantum algorithms, even considering parallel algorithms. - we observe that variations of shor ' s algorithm can take advantage of classical computations to reduce the number of quantum group operations. we introduce a model for generic hybrid quantum - classical algorithms and show that these algorithms are almost optimal in this model. any generic hybrid algorithm for the dl problem with a total number of group operations $ q $ must make $ \ omega ( \ log | g | / \ log q ) $ quantum group operations of depth $ \ omega ( \ log \ log | g | - \ log \ log q ) $. - when the quantum memory can only store $ t $ group elements and use quantum random access memory of $ r $ group elements, any generic hybrid algorithm must make either $ \ omega ( \ sqrt { | g | } ) $ group operations in total or $ \ omega ( \ log | g | / \ log ( tr ) ) $ quantum group operations. as a side contribution, we show a multiple dl problem admits a better algorithm than solving each instance one by one, refuting a strong form of the quantum annoying property suggested in the context of password - authenticated key exchange protocol. | arxiv:2307.03065 |
we study kinetic mixing between massless u ( 1 ) s in toroidal orbifolds with d3 - branes at orbifold singularities. we focus in particular on c ^ 3 / z _ 4 singularities but also study c ^ 3 / z _ 6 and c ^ 3 / z ' _ 6 singularities. we find kinetic mixing can be present and describe the conditions for it to occur. kinetic mixing comes from winding modes in the n = 2 sector of the orbifold. if kinetic mixing is present its size depends only on the complex structure modulus of the torus and is independent of the k \ " ahler moduli. we also study gauge threshold corrections for local z _ m x z _ n orbifold models finding that, consistent with previous studies, gauge couplings run from the bulk winding scale rather than the string scale. | arxiv:1009.2380 |
we study vector minimizers u of the allen - cahn functional with potentials possessing n global minima defined on bounded domains, with certain geometrical features and dirichlet conditions on the boundary. we derive a sharp lower bound for the energy ( as { \ epsilon } { \ rightarrow } 0 ) with the additional feature that it involves half of the gradient and part of the domain. based on this we derive very precise ( in { \ epsilon } ) pointwise estimates up to the boundary for u { \ epsilon }. depending on the geometry of the domain u { \ epsilon } exhibits either boundary layers or internal layers. we do not impose symmetry hypotheses. | arxiv:2110.00388 |
transport processes in the fully ionized plasma with kappa - distribution and in strong magnetic field are studied. by analyzing the current density and the heat flux in the kappa - distributed plasma, we derive the corresponding transport coefficients, including the electric conductivity, the thermal conductivity and thermoelectric coefficient. besides, we derive the coefficients of hall, nernst and leduc - righi effects in the kappa - distributed plasma. it is shown that these new transport coefficients depend strongly on the kappa - parameter and only in the limit kappa to infinity, they recover the traditional forms in the plasma based on a maxwellian distribution. we also numerically analyze the role of the kappa - parameter in the kappa - dependent transport coefficients. | arxiv:1903.04468 |
we consider the problem of estimating the difference between two undirected functional graphical models with shared structures. in many applications, data are naturally regarded as a vector of random functions rather than as a vector of scalars. for example, electroencephalography ( eeg ) data are treated more appropriately as functions of time. in such a problem, not only can the number of functions measured per sample be large, but each function is itself an infinite - dimensional object, making estimation of model parameters challenging. this is further complicated by the fact that curves are usually observed only at discrete time points. we first define a functional differential graph that captures the differences between two functional graphical models and formally characterize when the functional differential graph is well defined. we then propose a method, fudge, that directly estimates the functional differential graph without first estimating each individual graph. this is particularly beneficial in settings where the individual graphs are dense but the differential graph is sparse. we show that fudge consistently estimates the functional differential graph even in a high - dimensional setting for both fully observed and discretely observed function paths. we illustrate the finite sample properties of our method through simulation studies. we also propose a competing method, the joint functional graphical lasso, which generalizes the joint graphical lasso to the functional setting. finally, we apply our method to eeg data to uncover differences in functional brain connectivity between a group of individuals with alcohol use disorder and a control group. | arxiv:2003.05402 |
we investigate the three - state antiferromagnetic potts model on a simple cubic lattice with a cluster flipping monte carlo simulation algorithm in the temperature region below the transition into disorder at t _ { c1 }. we find both the well established broken - sublattice - symmetry ( bss ) phase at low temperature and a new, rotationally symmetric phase at higher temperature, but below t _ { c1 }. the properties of the second phase and the transition temperature to the bss phase are in disagreement with recent cluster - variation and monte carlo simulation results, but in agreement with simulations by kolesik and suzuki. | arxiv:cond-mat/9509140 |
for the nonlinear shr \ " odinger equation with disorder it was found numerically that in some regime of the parameters anderson localization is destroyed and subdiffusion takes place for a long time interval. it was argued that the nonlinear term acts as random noise. in the present work the properties of this effective noise are studied numerically. some assumptions made in earlier work were verified, the dependence of various quantities on the localization length of the linear problem were computed. a scenario for the possible breakdown of the theory for a very long time is outlined. | arxiv:1108.5867 |
the notion of wheeler languages is rooted in the burrows - wheeler transform ( bwt ), one of the most central concepts in data compression and indexing. the bwt has been generalized to finite automata, the so - called wheeler automata, by gagie et al. [ theor. comput. sci. 2017 ]. wheeler languages have subsequently been defined as the class of regular languages for which there exists a wheeler automaton accepting them. besides their advantages in data indexing, these wheelerlanguages also satisfy many interesting properties from a language theoretic point of view [ alanko et al., inf. comput. 2021 ]. a characteristic yet unsatisfying feature of wheeler languages however is that their definition depends on a fixed order of the alphabet. in this paper we introduce the universally wheeler languages uw, i. e., the regular languages that are wheeler with respect to all orders of a given alphabet. our first main contribution is to relate uw to some very well known regular language classes. we first show that the striclty locally testable languages are strictly included in uw. after noticing that uw is not closed under taking the complement, we prove that the class of languages for which both the language and its complement are in uw exactly coincides with those languages that are definite or reverse definite. secondly, we prove that deciding if a regular language given by a dfa is in uw can be done in quadratic time. we also show that this is optimal unless the strong exponential time hypothesis ( seth ) fails. | arxiv:2504.19537 |
recent years have seen extraordinary progress in creating quantum states of mechanical oscillators, leading to great interest in potential applications for such systems in both fundamental as well as applied quantum science. one example is the use of these devices as transducers between otherwise disparate quantum systems. in this regard, a promising approach is to build integrated piezoelectric optomechanical devices, that are then coupled to microwave circuits. optical absorption, low quality factors and other challenges have up to now prevented operation in the quantum regime, however. here, we design and characterize such a piezoelectric optomechanical device fabricated from gallium phosphide in which a 2. 9 ~ ghz mechanical mode is coupled to a high quality factor optical resonator in the telecom band. the large electronic bandgap and the resulting low optical absorption of this new material, on par with devices fabricated from silicon, allows us to demonstrate quantum behavior of the structure. this not only opens the way for realizing noise - free quantum transduction between microwaves and optics, but in principle also from various color centers with optical transitions in the near visible to the telecom band. | arxiv:1909.07850 |
the numerical study indicates that there exists a relation between the quasinormal modes and the davies point for a black hole. in this paper, we analytically study this relation for the charged reissner - nordstr \ " { o } m black holes in asymptotically flat and ds spacetimes. in the eikonal limit, the angular velocity $ \ omega $ and the lyapunov exponent $ \ lambda $ of the photon sphere, respectively, corresponding to the real and imaginary parts of the quasinormal modes are obtained from the null geodesics. both in asymptotically flat and ds spacetimes, we observe the spiral - like shapes in the complex quasinormal mode plane. however, the starting point of the shapes do not coincide with the davies point. nevertheless, we find a new relation that the davies point exactly meet the maximum of the temperature $ t $ in the $ t $ - $ \ omega $ and $ t $ - $ \ lambda $ planes. in higher dimensional asymptotically flat spacetime, even there is no the spiral - like shape, such relation still holds. therefore, we provide a new relation between the black hole thermodynamics and dynamics. applying this relation, we can test the black hole thermodynamic property by the quasinormal modes. | arxiv:1909.11911 |
the udp ( user defined program ) system is a scripting framework for controlling and extending instrumentation software. it has been specially designed for air - and space - borne instruments with flexibility, error control, reuse, automation, traceability and ease of development as its main objectives. all the system applications are connected through a database containing the valid script commands including descriptive information and source code. the system can be adapted to different projects without changes in the framework tools, thus achieving great level of flexibility and reusability. the udp system comprises : an embedded system for the execution of scripts by the instrument software ; automatic tools for aiding in the creation, modification, documentation and tracing of new scripting language commands ; and interfaces for the creation of scripts and execution control. | arxiv:0807.4035 |
let $ \ mathcal { a } _ 1, \ ldots, \ mathcal { a } _ m $ be families of $ k $ - subsets of an $ n $ - set. suppose that one cannot choose pairwise disjoint edges from $ s + 1 $ distinct families. subject to this condition we investigate the maximum of $ | \ mathcal { a } _ 1 | + \ ldots + | \ mathcal { a } _ m | $. note that the subcase $ m = s + 1 $, $ \ mathcal { a } _ 1 = \ ldots = \ mathcal { a } _ m $ is the erd \ h { o } s matching conjecture, one of the most important open problems in extremal set theory. we provide some upper bounds, a general conjecture and its solution for the range $ n \ geq 4k ^ 2s $. | arxiv:2105.00481 |
in this paper, we propose a method to create visuomotor mobile manipulation solutions for long - horizon activities. we propose to leverage the recent advances in simulation to train visual solutions for mobile manipulation. while previous works have shown success applying this procedure to autonomous visual navigation and stationary manipulation, applying it to long - horizon visuomotor mobile manipulation is still an open challenge that demands both perceptual and compositional generalization of multiple skills. in this work, we develop mobile - ember, or m - ember, a factorized method that decomposes a long - horizon mobile manipulation activity into a repertoire of primitive visual skills, reinforcement - learns each skill, and composes these skills to a long - horizon mobile manipulation activity. on a mobile manipulation robot, we find that m - ember completes a long - horizon mobile manipulation activity, cleaning _ kitchen, achieving a 53 % success rate. this requires successfully planning and executing five factorized, learned visual skills. | arxiv:2305.13567 |
we argue that the non - detection of oscillations in procyon by the most satellite reported by matthews et al. ( 2004 ) is fully consistent with published ground - based velocity observations of this star. we also examine the claims that the most observations represent the best photometric precision so far reported in the literature by about an order of magnitude and are the most sensitive data set for asteroseismology available for any star other than the sun. these statements are not correct, with the most notable exceptions being observations of oscillations in alpha cen a that are far superior. we further disagree that the hump of excess power seen repeatedly from velocity observations of procyon can be explained as an artefact caused by gaps in the data. the most observations failed to reveal oscillations clearly because their noise level is too high, possibly from scattered earthlight in the instrument. we did find an excess of strong peaks in the most amplitude spectrum that is inconsistent with a simple noise source such as granulation, and may perhaps indicate oscillations at roughly the expected level. | arxiv:astro-ph/0501662 |
the utility of smartphones has been limited to a great extent by their short battery life. in this work, we propose a new approach to prolonging smartphone battery life. we introduce the notions of " valueless " and " valued battery ", as being the available battery when the user does or does not have access to a power source, respectively. we propose a cooperative system where users with high battery level help carry the traffic of users with low battery level. our scheme helps increase the amount of valued battery in the network, thus it reduces the chance of users running out of battery early. our system can be realized in the form of a proximity service ( prose ) which utilizes a device - to - device ( d2d ) communication architecture underlaying lte. we show through simulations that our system reduces the probability of cellular users running out of battery before their target usage time ( probability of outage ). our simulator source code is made available to the public. | arxiv:1401.5826 |
a semi - empirical mechanistic contact law for micro - crystalline cellulose ( avicel ph - 200 ) particles is proposed and characterized experimentally using force - displacement curves obtained from diametrical compression of single particles. the concepts of a shape factor and a master contact law are introduced first for elastic ellipsoidal particles, and subsequently generalized to plastic irregular particles. the proposed loading - unloading contact law is a function of three characteristic diameters ( lengths of the principal axes of an approximated ellipsoid ), a geometric parameter associated with the loading condition, three plastic and one elastic material properties. the force - displacement curves obtained using a micro - compression tester exhibit an apparent strain - hardening at distinctly different strain values, which is captured by the shape factor function and its geometric parameter. the three plastic material properties are log - normal distributions estimated from the loading experimental curves, while the elastic property is estimated from the unloading experimental curves. the study shows a very good agreement between predictions of the calibrated loading - unloading contact law and the experimental values. | arxiv:1812.06173 |
the correlation between the mean transverse momentum and the harmonic flow coefficients is an observable which is of great interest ; it is sensitive to shape fluctuations in the initial state of a relativistic nuclear collision. the measurement of that correlation coefficient in central collisions allows one to infer about the intrinsic deformation of the colliding nuclei. we propose to study the momentum dependent covariance and correlation coefficient between the mean transverse momentum and the harmonic flow in a given transverse momentum bin. two possible constructions of such observables are provided and predictions are obtained from a viscous hydrodynamic model. we find that such momentum dependent correlation coefficients between the mean transverse momentum and the harmonic flow show a strong and nontrivial momentum dependence. we also explore the effects of granularity ( nucleon width ) in the initial state, the nuclear deformation, and the shear viscosity on this momentum dependent correlation coefficient. the shape of the momentum dependence of the correlation coefficient for the triangular flow is found to be sensitive to the size of small scale fluctuations in the initial state. on the other hand, the shape of the momentum dependence of the covariance between the mean transverse momentum and the harmonic flow coefficients is found to be sensitive to the value of the shear viscosity and to the granularity of the initial state. | arxiv:2308.11565 |
out - of - distribution data and anomalous inputs are vulnerabilities of machine learning systems today, often causing systems to make incorrect predictions. the diverse range of data on which these models are used makes detecting atypical inputs a difficult and important task. we assess a tool, benford ' s law, as a method used to quantify the difference between real and corrupted inputs. we believe that in many settings, it could function as a filter for anomalous data points and for signalling out - of - distribution data. we hope to open a discussion on these applications and further areas where this technique is underexplored. | arxiv:2403.15497 |
we introduce riemannian metrics of positive scalar curvature on manifolds with baas - sullivan singularities, prove a corresponding homology invariance principle and discuss admissible products. using this theory we construct positive scalar curvature metrics on closed smooth manifolds of dimension at least five which have odd order abelian fundamental groups, are nonspin and atoral. this solves the gromov - lawson - rosenberg conjecture for a new class of manifolds with finite fundamental groups. | arxiv:1908.00944 |
there has been strong interest among higher education institution in implementing technology - enhanced peer assessment as a tool for enhancing students ' learning. however, little is known on how to use the peer assessment system in pre - instructional activities. this study aims to explore how technology - enhanced peer assessment can be embedded into pre - instructional activities to enhance students ' learning. therefore, the present study was an explorative descriptive study that used the qualitative approach to attain the research aim. this study used a questionnaire, students ' reflections, and interview in collecting student ' s perceptions toward the interventions. the results suggest that the technology - enhanced pre - instructional peer assessment helps students to prepare the new content acquisition and become a source of students ' motivation in improving their learning performance for the following main body of the lesson. a set of practical suggestions is also proposed for designing and implementing technology - enhanced pre - instructional peer assessment. | arxiv:2002.04916 |
context. we report the detection by the agile satellite of an intense gamma - ray flare from the gamma - ray source 3eg j1255 - 0549, associated to the flat spectrum radio quasar 3c 279, during the agile pointings towards the virgo region on 2007 july 9 - 13. aims. the simultaneous optical, x - ray and gamma - ray covering allows us to study the spectral energy distribution ( sed ) and the theoretical models relative to the flaring episode of mid - july. methods. agile observed the source during its science performance verification phase with its two co - aligned imagers : the gamma - ray imaging detector ( grid ) and the hard x - ray imager ( super - agile ) sensitive in the 30 mev - 50 gev and 18 - 60 kev respectively. during the agile observation the source was monitored simultaneously in optical band by the rem telescope and in the x - ray band by the swift satellite through 4 too observations. results. during 2007 july 9 - 13 july 2007, agile - grid detected gamma - ray emission from 3c 279, with the source at ~ 2 deg from the center of the field of view, with an average flux of ( 210 + - 38 ) 10 ^ - 8 ph cm ^ - 2 s ^ - 1 for energy above 100 mev. no emission was detected by super - agile, with a 3 - sigma upper limit of 10 mcrab. during the observation lasted about 4 days no significative gamma - ray flux variation was observed. conclusions. the spectral energy distribution is modelled with a homogeneous one - zone synchrotron self compton emission plus the contributions by external compton scattering of direct disk radiation and, to a lesser extent, by external compton scattering of photons from the broad line region. | arxiv:0810.2189 |
vision large language models ( vllms ) integrate visual data processing, expanding their real - world applications, but also increasing the risk of generating unsafe responses. in response, leading companies have implemented multi - layered safety defenses, including alignment training, safety system prompts, and content moderation. however, their effectiveness against sophisticated adversarial attacks remains largely unexplored. in this paper, we propose multifaceted attack, a novel attack framework designed to systematically bypass multi - layered defenses in vllms. it comprises three complementary attack facets : visual attack that exploits the multimodal nature of vllms to inject toxic system prompts through images ; alignment breaking attack that manipulates the model ' s alignment mechanism to prioritize the generation of contrasting responses ; and adversarial signature that deceives content moderators by strategically placing misleading information at the end of the response. extensive evaluations on eight commercial vllms in a black - box setting demonstrate that multifaceted attack achieves a 61. 56 % attack success rate, surpassing state - of - the - art methods by at least 42. 18 %. | arxiv:2502.05772 |
we show that the quantum hall wave functions for the ground states in the jain series can be exactly expressed in terms of correlation functions of local vertex operators, v _ n, corresponding to composite fermions in the n : th composite - fermion ( cf ) landau level. this allows for the powerful mathematics of conformal field theory to be applied to the successful cf phenomenology. quasiparticle and quasihole states are expressed as correlators of anyonic operators with fractional ( local ) charge, allowing a simple algebraic understanding of their topological properties that are not manifest in the cf wave functions. | arxiv:cond-mat/0603125 |
we derive here a robust bound on the effective number of neutrinos from constraints on primordial nucleosynthesis yields of deuterium and helium. in particular, our results are based on very weak assumptions on the astrophysical determination of the helium abundance, namely that the minimum effect of stellar processing is to keep constant ( rather than increase, as expected ) the helium content of a low - metallicity gas. using the results of a recent analysis of extragalactic hii regions as upper limit, we find that delta neff < = 1 at 95 % c. l., quite independently of measurements on the baryon density from cosmic microwave background anisotropy data and of the neutron lifetime input. in our approach, we also find that primordial nucleosynthesis alone has no significant preference for an effective number of neutrinos larger than the standard value. the ~ 2 sigma hint sometimes reported in the literature is thus driven by cmb data alone and / or is the result of a questionable regression protocol to infer a measurement of primordial helium abundance. | arxiv:1103.1261 |
convolutional neural networks model the transformation of the input sensory data at the bottom of a network hierarchy to the semantic information at the top of the visual hierarchy. feedforward processing is sufficient for some object recognition tasks. top - down selection is potentially required in addition to the bottom - up feedforward pass. it can, in part, address the shortcoming of the loss of location information imposed by the hierarchical feature pyramids. we propose a unified 2 - pass framework for object segmentation that augments bottom - up \ convnets with a top - down selection network. we utilize the top - down selection gating activities to modulate the bottom - up hidden activities for segmentation predictions. we develop an end - to - end multi - task framework with loss terms satisfying task requirements at the two ends of the network. we evaluate the proposed network on benchmark datasets for semantic segmentation, and show that networks with the top - down selection capability outperform the baseline model. additionally, we shed light on the superior aspects of the new segmentation paradigm and qualitatively and quantitatively support the efficiency of the novel framework over the baseline model that relies purely on parametric skip connections. | arxiv:2002.01125 |
a vertical connection of water is formed when a high voltage electrode is dipped in and pulled out of a container of deionized water. we considered the formation and dynamical characteristics of this vertical water bridge. for the first time in this field, instabilities were observed in the bridge that led to an oscillatory behaviour which we categorized them into three dynamical regimes. some explanations were supplied on the physics behind these dynamics. we report the formation of macroscopic droplets during our experiments, which their dynamics revealed that they are electrically charged. in some cases the droplets levitated in the air due to the equality of gravity and electrical force ( acting in the opposite direction ). our results shed light on the physics behind this phenomenon and the horizontal water bridge, which explanations regarding its underlying physics have led to controversial theories and discussions before. | arxiv:1309.2222 |
we have investigated the potential energy surfaces for glycine chains consisting of three and six amino acids. for these molecules we have calculated potential energy surfaces as a function of the ramachandran angles phi and psi, which are widely used for the characterization of the polypeptide chains. these particular degrees of freedom are essential for the characterization of proteins folding process. calculations have been carried out within ab initio theoretical framework based on the density functional theory and accounting for all the electrons in the system. we have determined stable conformations and calculated the energy barriers for transitions between them. using a thermodynamic approach, we have estimated the times of the characteristic transitions between these conformations. the results of our calculations have been compared with those obtained by other theoretical methods and with the available experimental data extracted from the protein data base. this comparison demonstrates a reasonable correspondence of the most prominent minima on the calculated potential energy surfaces to the experimentally measured angles phi and psi for the glycine chains appearing in native proteins. we have also investigated the influence of the secondary structure of polypeptide chains on the formation of the potential energy landscape. this analysis has been performed for the sheet and the helix conformations of chains of six amino acids. | arxiv:physics/0511026 |
this paper introduces a novel method for emulating piano sounds. we propose to exploit the sines, transient, and noise decomposition to design a differentiable spectral modeling synthesizer replicating piano notes. three sub - modules learn these components from piano recordings and generate the corresponding harmonic, transient, and noise signals. splitting the emulation into three independently trainable models reduces the modeling tasks ' complexity. the quasi - harmonic content is produced using a differentiable sinusoidal model guided by physics - derived formulas, whose parameters are automatically estimated from audio recordings. the noise sub - module uses a learnable time - varying filter, and the transients are generated using a deep convolutional network. from singular notes, we emulate the coupling between different keys in trichords with a convolutional - based network. results show the model matches the partial distribution of the target while predicting the energy in the higher part of the spectrum presents more challenges. the energy distribution in the spectra of the transient and noise components is accurate overall. while the model is more computationally and memory efficient, perceptual tests reveal limitations in accurately modeling the attack phase of notes. despite this, it generally achieves perceptual accuracy in emulating single notes and trichords. | arxiv:2409.06513 |
we propose a methodology to estimate the market value of pharmaceutical drugs. our approach combines an event study with a model of discounted cash flows and uses stock market responses to drug development announcements to infer the values. we estimate that, on average, a successful drug is valued at \ $ 1. 62 billion, and its value at the discovery stage is \ $ 64. 3 million, with substantial heterogeneity across major diseases. leveraging these estimates, we also determine the average drug development costs at various stages. furthermore, we explore applying our estimates to design policies that support drug development through drug buyouts and cost - sharing agreements. | arxiv:2212.07384 |
high - quality video inpainting that completes missing regions in video frames is a promising yet challenging task. state - of - the - art approaches adopt attention models to complete a frame by searching missing contents from reference frames, and further complete whole videos frame by frame. however, these approaches can suffer from inconsistent attention results along spatial and temporal dimensions, which often leads to blurriness and temporal artifacts in videos. in this paper, we propose to learn a joint spatial - temporal transformer network ( sttn ) for video inpainting. specifically, we simultaneously fill missing regions in all input frames by self - attention, and propose to optimize sttn by a spatial - temporal adversarial loss. to show the superiority of the proposed model, we conduct both quantitative and qualitative evaluations by using standard stationary masks and more realistic moving object masks. demo videos are available at https : / / github. com / researchmm / sttn. | arxiv:2007.10247 |
we theoretically investigate spin dynamics in spin - orbit - coupled materials. in the ballistic limit, the spin lifetime is dictated by dephasing that arises from energy broadening plus a non - uniform spin precession. for the case of clean graphene, we find a strong anisotropy with spin lifetimes that can be short even for modest energy scales, on the order of a few ns. these results offer deeper insight into the nature of spin dynamics in graphene, and are also applicable to the investigation of other systems where spin - orbit coupling plays an important role. | arxiv:1602.04611 |
this paper proves an elementary topological fact about closed curves on surfaces, namely that by carefully smoothing an intersection point, one can reduce self - intersection by exactly $ 1 $. this immediately implies a positive answer to a problem first raised by basmajian in the 1990s : among all closed geodesics of a hyperbolic surface that self - intersect at least $ k $ times, does the shortest one self - intersect exactly $ k $ times? the answer is also shown to be positive for arbitrary riemannian metrics. | arxiv:2308.10271 |
an improved algorithm is proposed for the reconstruction of singular connectivity from the available pairwise connections during preprocessing phase. to evaluate the performance of the algorithm, an in - house computational fluid dynamics ( cfd ) code is used in which high - order finite - difference method for spatial discretization running on the tianhe - 1a supercomputer is employed. test cases with a varied amount of mesh points are chosen, and the test results indicate that the improved singular connection reconstruction algorithm can achieve a speedup factor of 1000x or more when compared with the naive search method adopted in the former version of our code. moreover, the parallel efficiency can benefit from the strategy of local communication based on the algorithm. | arxiv:1711.00110 |
in this work, we analyze the observational properties of thin - shell gravastars under two astrophysical frameworks, namely surrounded by optically - thin accretion disks and orbited by hot - spots. we consider the thin - shell gravastar model with two free parameters, the gravastar radius and ratio of mass allocated at the thin - shell, and produce the corresponding observables via the use of numerical backwards ray - tracing codes. regarding the observations of accretion disks, our results indicate that, due to the absence of a strong gravitational redshift effect, smooth gravastar configurations cannot reproduce shadow observations when internal emission is assumed. we thus expect such models to be excluded as candidates for supermassive objects in galactic cores. nevertheless, thin - shell gravastars with a large portion of their total mass allocated at the surface can produce such an effect and are thus adequate candidates for black - hole mimickers. in the context of hot - spot orbits, the astrometrical observational properties of ultra - compact gravastars resemble closely those of other ultra - compact objects e. g. fluid stars and bosonic stars. however, for low - compacticity configurations, the time - integrated fluxes feature additional contributions in the form of a high - intensity plunge through image. these qualitative differences in the observational properties of gravastars in comparison with black - hole spacetimes could potentially be discriminated by the next generation of interferometric experiments in gravitational physics. | arxiv:2401.07766 |
though multi - modal large language models ( mllms ) have recently achieved significant progress, they often face various problems while handling inter - object relations, i. e., the interaction or association among distinct objects. this constraint largely stems from insufficient training and evaluation data for relation understanding, which has greatly impeded mllms in various vision - language generation and reasoning tasks. we attempt to address this challenge by introducing multi - modal relation understanding ( mmrel ), a benchmark that features large - scale, high - quality, and diverse data on inter - object relations. mmrel features three distinctive attributes : ( i ) it contains over 22k question - answer pairs, spanning three distinct domains and covering three relation categories, ensuring both scale and diversity ; ( ii ) it provides manually verified, high - quality labels to ensure exceptional annotation accuracy ; ( iii ) it includes adversarial cases with highly unusual relations, offering a challenging setting for evaluating relation hallucination. these features make mmrel ideal for evaluating mllms on relation understanding, as well as for fine - tuning mllms to enhance relation comprehension capability. extensive experiments verify the effectiveness of mmrel in evaluating and enhancing mllms ' relation understanding capabilities. the benchmark has been released publicly at : https : / / niejiahao1998. github. io / mmrel / | arxiv:2406.09121 |
it is an english translation of the paper originally published in russian and ukrainian in 1987. in the appendix of his book s. banach introduced the following definition let $ x $ be a banach space and $ \ gamma $ be a subspace of the dual space $ x ^ * $. the set of all limits of $ w ^ { * } $ - convergent sequences in $ \ gamma $ is called the $ w ^ * $ { \ it - derived set } of $ \ gamma $ and is denoted by $ \ gamma _ { ( 1 ) } $. for an ordinal $ \ alpha $ the $ w ^ { * } $ - { \ it derived set of order } $ \ alpha $ is defined inductively by the equality : $ $ \ gamma _ { ( \ alpha ) } = \ bigcup _ { \ beta < \ alpha } ( ( \ gamma _ { ( \ beta ) } ) _ { ( 1 ) }. $ $ | arxiv:math/9303203 |
detection of effects of the parameters of the synthetic process on the microstructure of materials is an important, yet elusive goal of materials science. we develop a method for detecting effects based on copula theory, high dimensional distribution distances, and permutational statistics to analyze a designed experiment synthesizing plutonium oxide from pu ( iii ) oxalate. we detect effects of strike order and oxalic acid feed on the microstructure of the resulting plutonium oxide, which match the literature well. we also detect excess bivariate effects between the pairs of acid concentration, strike order and precipitation temperature. | arxiv:2304.01120 |
preparing long - range entangled states poses significant challenges for near - term quantum devices. it is known that measurement and feedback ( mf ) can aid this task by allowing the preparation of certain paradigmatic long - range entangled states with only constant circuit depth. here we systematically explore the structure of states that can be prepared using constant - depth local circuits and a single mf round. using the framework of tensor networks, the preparability under mf translates to tensor symmetries. we detail the structure of matrix - product states ( mps ) and projected entangled - pair states ( peps ) that can be prepared using mf, revealing the coexistence of clifford - like properties and magic. in one dimension, we show that states with abelian symmetry protected topological order are a restricted class of mf - preparable states. in two dimensions, we parameterize a subset of states with abelian topological order that are mf - preparable. finally, we discuss the analogous implementation of operators via mf, providing a structural theorem that connects to the well - known clifford teleportation. | arxiv:2405.09615 |
despite ongoing research, the rational design of nontrivial topological semimetal surface states for the selective photocatalytic co $ _ 2 $ conversion into valuable products remains full of challenges. herein, we present the synthesis of 1t - oscote $ _ 2 $ for the photoreduction upgrading of co $ _ 2 $ to tricarbon alkane c $ _ 3 $ h $ _ 8 $, by the integration of experimental work and theory calculation. experimental studies suggested a high electron based selectivity of 71. 2 % for c $ _ 3 $ h $ _ 8 $ and an internal quantum efficiency of 54. 6 % at 380 nm. in - situ x - ray photoelectron spectroscopy and x - ray absorption fine structure spectroscopy demonstrated that co and os atoms coordinated with te atoms enable an efficient os - te - co electron transfer to activate the generation of * ch $ _ 3 $, * choco and * ch $ _ 2 $ ococo. density functional theory calculations further confirmed os - te - co electron bridging on the improved co $ _ 2 $ conversion kinetics. to our knowledge, this is the first report suggesting the role of os atoms in accelerating the photocatalytic co $ _ 2 $ conversion activity of the topological semimetal 1t - oscote $ _ 2 $. | arxiv:2408.11369 |
this work proposes a method for source device identification from speech recordings that applies neural - network - based denoising, to mitigate the impact of counter - forensics attacks using noise injection. the method is evaluated by comparing the impact of denoising on three state - of - the - art features for microphone classification, determining their discriminating power with and without denoising being applied. the proposed framework achieves a significant performance increase for noisy material, and more generally, validates the usefulness of applying denoising prior to device identification for noisy recordings. | arxiv:2206.11640 |
stability of dark solitons generated by a supersonic flow of bose - einstein condensate past an obstacle is investigated. it is shown that in the reference frame attached to the obstacle a transition occurs at some critical value of the flow velocity from absolute instability of dark solitons to their convective instability. this leads to decay of disturbances of solitons at fixed distance from the obstacle and formation of effectively stable dark solitons. this phenomenon explains surprising stability of the flow picture that has been observed in numerical simulations. | arxiv:0712.1891 |
to include parameter uncertainty into probabilistic climate forecasts one must first specify a prior. we advocate the use of objective priors, and, in particular, the jeffreys ' prior. in previous work we have derived expressions for the jeffreys ' prior for the case in which the observations are independent and normally distributed. these expressions make the calculation of the prior much simpler than evaluation directly from the definition. in this paper, we now relax the independence assumption and derive expressions for the jeffreys ' prior for the case in which the observations are distributed with a multivariate normal distribution with constant covariances. again, these expressions simplify the calculation of the prior : in this case they reduce it to the calculation of the differences between the ensemble means of climate model ensembles based on different parameter settings. these calculations are simple enough to be applied to even the most complex climate models. | arxiv:1005.2354 |
we generalize the hyperplane inequality in dimensions up to 4 to the setting of arbitrary measures in place of the volume. to prove this generalization we establish stability in the affirmative part of the solution to the busemann - petty problem asking whether symmetric convex bodies in r ^ n with smaller ( n - 1 ) - dimensional volume of all central hyperplane sections necessarily have smaller n - dimensional volume. | arxiv:1102.4081 |
the tunneling through an opaque barrier with a strong oscillating component is investigated. it is shown, that in the strong perturbations regime ( in contrast to the weak one ), higher perturbations rate does not necessarily improve the activation. in fact, in this regime two rival factors play a role, and as a consequence, this tunneling system behaves like a sensitive frequency - shifter device : for most incident particles ' energies activation occurs and the particles are energetically elevated, while for specific energies activation is depressed and the transmission is very low. this effect is unique to the strong perturbation regime, and it is totally absent in the weak perturbation case. moreover, it cannot be deduced even in the adiabatic regime. it is conjectured that this mechanism can be used as a frequency - dependent transistor, in which the device ' s transmission is governed by the external field frequency. | arxiv:quant-ph/0112167 |
assuming the completeness condition for boundaries we derive trace formulas for the annulus coefficients in 2 - dimensional conformal field theory. we also derive polynomial equations that relate the annulus, moebius and klein bottle coefficients, and conjecture an annulus trace formula that is sensitive to the orientation of the boundaries. | arxiv:hep-th/0108035 |
recently, the problem of boundary stabilization for unstable linear constant - coefficient reaction - diffusion equation on n - balls has been solved by means of the backstepping method. however, the extension of this result to spatially - varying coefficients is far from trivial. this work deals with radially - varying reaction coefficients under revolution symmetry conditions on a disk ( the 2 - d case ). under these conditions, the equations become singular in the radius. when applying the backstepping method, the same type of singularity appears in the backstepping kernel equations. traditionally, well - posedness of the kernel equations is proved by transforming them into integral equations and then applying the method of successive approximations. in this case, the resulting integral equation is singular. a successive approximation series can still be formulated, however its convergence is challenging to show due to the singularities. the problem is solved by a rather non - standard proof that uses the properties of the catalan numbers, a well - known sequence frequently used in combinatorial mathematics. | arxiv:1601.02010 |
the problem of identifying a planted assignment given a random $ k $ - sat formula consistent with the assignment exhibits a large algorithmic gap : while the planted solution becomes unique and can be identified given a formula with $ o ( n \ log n ) $ clauses, there are distributions over clauses for which the best known efficient algorithms require $ n ^ { k / 2 } $ clauses. we propose and study a unified model for planted $ k $ - sat, which captures well - known special cases. an instance is described by a planted assignment $ \ sigma $ and a distribution on clauses with $ k $ literals. we define its distribution complexity as the largest $ r $ for which the distribution is not $ r $ - wise independent ( $ 1 \ le r \ le k $ for any distribution with a planted assignment ). our main result is an unconditional lower bound, tight up to logarithmic factors, for statistical ( query ) algorithms [ kearns 1998, feldman et. al 2012 ], matching known upper bounds, which, as we show, can be implemented using a statistical algorithm. since known approaches for problems over distributions have statistical analogues ( spectral, mcmc, gradient - based, convex optimization etc. ), this lower bound provides a rigorous explanation of the observed algorithmic gap. the proof introduces a new general technique for the analysis of statistical query algorithms. it also points to a geometric paring phenomenon in the space of all planted assignments. we describe consequences of our lower bounds to feige ' s refutation hypothesis [ feige 2002 ] and to lower bounds on general convex programs that solve planted $ k $ - sat. our bounds also extend to other planted $ k $ - csp models, and, in particular, provide concrete evidence for the security of goldreich ' s one - way function and the associated pseudorandom generator when used with a sufficiently hard predicate [ goldreich 2000 ]. | arxiv:1311.4821 |
deep learning ( dl ) - based solutions have recently been developed for communication protocol design. such learning - based solutions can avoid manual efforts to tune individual protocol parameters. while these solutions look promising, they are hard to interpret due to the black - box nature of the ml techniques. to this end, we propose a novel drl - based framework to systematically design and evaluate networking protocols. while other proposed ml - based methods mainly focus on tuning individual protocol parameters ( e. g., adjusting contention window ), our main contribution is to decouple a protocol into a set of parametric modules, each representing a main protocol functionality and is used as drl input to better understand the generated protocols design optimization and analyze them in a systematic fashion. as a case study, we introduce and evaluate deepmac a framework in which a mac protocol is decoupled into a set of blocks across popular flavors of 802. 11 wlans ( e. g., 802. 11a / b / g / n / ac ). we are interested to see what blocks are selected by deepmac across different networking scenarios and whether deepmac is able to adapt to network dynamics. | arxiv:2002.02075 |
we study the effect of sigma meson on the $ d _ 1 ( 2430 ) \ to d \ pi \ pi $ decay by constructing an effective lagrangian preserving the chiral symmetry and the heavy quark symmetry. the sigma meson is included through a linear sigma model, in which both the $ q \ bar { q } $ and $ qq \ bar { q } \ bar { q } $ states are incorporated respecting their different $ u ( 1 ) _ { a } $ transformation properties. we first fit the sigma meson mass and $ \ sigma $ - $ \ pi $ - $ \ pi $ coupling constant to the i = 0, $ s $ - wave $ \ pi $ - $ \ pi $ scattering data. then, we show how the differential decay width $ d \ gamma ( d _ 1 \ to d ( \ pi \ pi ) _ { i = 0, l = 0 } ) / d m _ { \ pi \ pi } $ depends on the quark structure of the sigma meson. we find that our study, combing with the future data, can give a clue to understand the sigma meson structure. | arxiv:1203.3632 |
we show that in parametrically driven systems and, more generally, in systems in coherent states, off - resonant pumping can cause a transition from a continuum energy spectrum of the system to a discrete one, and result in quantum revivals of the initial state. the mechanism responsible for quantum revivals in the present case is different from that in the non - linear wavepacket dynamics of systems such as rydberg atoms. we interpret the reported phenomena as an optical analog of bloch oscillations realized in fock space and propose a feasible scheme for inducing bloch oscillations in trapped ions. | arxiv:quant-ph/0008106 |
an unstable torsion free sheaf on a smooth projective variety gives a git unstable point in certain quot scheme. to a git unstable point, kempf associates a " maximally destabilizing " 1 - parameter subgroup, and this induces a filtration of the torsion free sheaf. we show that this filtration coincides with the harder - narasimhan filtration. | arxiv:1112.1886 |
present - day experimental and phenomenological situation about pseudoscalar ( $ \ pi ^ 0 $, $ \ eta $, $ \ eta ' $ ) meson transition form factors is briefly reviewed. necessity of more sophisticated behaviours in time - like region of these form factors is emphasized. four - resonance unitary and analytic model of the pseudoscalar meson transition form factors is constructed, which describes well all existing experimental information. | arxiv:hep-ph/0401007 |
the reflection length of an element of a coxeter group is the minimal number of conjugates of the standard generators whose product is equal to that element. in this paper we prove the conjecture of mccammond and petersen that reflection length is unbounded in any non - affine coxeter group. among the tools used, the construction of word - hyperbolic quotients of all minimal non - affine coxeter groups might be of independent interest. | arxiv:1106.0619 |
precise measurements of the mass of the $ w $ boson are important to test the overall consistency of the standard model of particle physics. the current best measurements of the $ w $ boson mass come from single production measurements at hadron colliders in its decay mode to a lepton ( electron or muon ) and a neutrino and pair production of $ w $ bosons at lepton colliders, where also the decay mode of the $ w $ boson to hadrons has been considered. in this study, prospects for a measurement of the $ w $ boson mass in the all - jet final state at hadron colliders are presented. the feasibility of this measurement takes advantage of numerous recent developments in the field of jet substructure. compared to other methods for measuring the $ w $ mass, a measurement in the all - jets final state would be complementary in methodology and have systematic uncertainties orthogonal to previous measurements. we have estimated the main experimental and theoretical uncertainties affecting a measurement in the all - jet final state. with new trigger strategies, a statistical uncertainty for the measurement of the mass difference between the $ z $ and $ w $ bosons of 30 mev could be reached with hl - lhc data corresponding to 3000 fb $ ^ { - 1 } $ of integrated luminosity. however, in order to reach that precision, the current understanding of non - perturbative contributions to the invariant mass of $ w \ to q \ bar { q } ' $ and $ z \ to b \ bar { b } $ jets will need to be refined. similar strategies will also allow the reach for generic boosted resonances searches in hadronic channels to be extended. | arxiv:1807.07454 |
we present cosmological constraints for the flat $ \ lambda $ cdm model, including the sum of neutrino masses, by performing a multi - probe analysis of a total of 13 tomographic auto - and cross - angular power spectra. this is achieved by combining, at map level, the latest primary cmb and cmb - lensing measurements from the planck 2018 data release, as well as spectroscopic galaxy samples from boss dr12, and the latest kilo - degree survey ( kids - 1000 ) tomographic weak lensing shear data release. our analysis includes auto - and cross - correlations as well as calibration parameters for all cosmological probes, thus providing a self - calibration of the combined data sets. we find a good fit ( reduced $ \ chi ^ 2 $ = 1. 7 ) for the combined probes with calibration parameters only moderately different from their nominal value, thus giving a possible interpretation of the tension between the early - and late - universe probes. the resulting value for the structure growth parameter is $ s _ 8 = 0. 754 \ pm 0. 016 $ ( 68 \ % cl ). we also obtain a $ \ sim $ 2. 3 $ \ sigma $ constraint on the neutrino mass sum of $ \ sum m _ \ nu = 0. 51 ^ { + 0. 21 } _ { - 0. 24 } $ ev ( 68 \ % cl ), which is compatible with current particle physics limits. we perform several tests by fixing the neutrino mass sum to a low value, considering narrower priors on the multiplicative bias parameters for cosmic shear, and by fixing all calibration parameters to their expected values. these tests result in worse fits compared to our fiducial run, especially for the case when all calibration parameters are fixed. this latter test also yields a lower upper limit of the neutrino mass sum. we discuss how the interplay between the cosmological and calibration parameters impact the $ s _ 8 $ - tension and the constraints on the neutrino mass sum. [ abridged ] | arxiv:2110.03815 |
percolation is the paradigm for random connectivity and has been one of the most applied statistical models. with simple geometrical rules a transition is obtained which is related to magnetic models. this transition is, in all dimensions, one of the most robust continuous transitions known. we present a very brief overview of more than 60 years of work in this area and discuss several open questions for a variety of models, including classical, explosive, invasion, bootstrap, and correlated percolation. | arxiv:1404.5325 |
the vortex dynamics of a d + is - wave superconductor is studied numerically by simulating the time - dependent ginzburg - landau equations. the critical fields, the free flux flow, and the flux flow in the presence of twin - boundaries are discussed. the relaxation rate of the order parameter turns out to play an important role in the flux flow. we also address briefly the intrinsic hall effect in d - and d + is - wave superconductors. | arxiv:cond-mat/9906211 |
i propose an extension to boltzmann bgk equation for hard spheres. the present model has an $ h $ - theorem and it allows choice of prandtl number as an independent parameter. i show that similar to enskog equation this equation can reproduce dynamics of hard spheres in dense systems. | arxiv:0806.4479 |
this paper contains a revised version of the lecture notes of a short course on the quantization of gauge theories. starting from a sketchy review of scattering theory, the paper describes the lines of brst - faddeev - popov quantization considering the problem of a non - perturbative extension of this method. the connection between slavnov - taylor identity and s - matrix unitarity is also discussed. | arxiv:hep-th/9607181 |
reynolds averaged navier stokes ( rans ) modelling is notorious for introducing the model - form uncertainty due to the boussinesq turbulent viscosity hypothesis. recently, the eigenspace perturbation method ( epm ) has been developed to estimate the rans model - form uncertainty. this approach estimates model - form uncertainty through injecting perturbations to the predicted reynolds stress tensor. however, there is a need for a reliable machine learning method for estimating the perturbed amplitude of the reynolds stress tensor. machine learning models are often too complex and data intensive for this application. we propose a lightweight convolutional neural network ( cnn ) approach to learn a correction function for rans from paired - samples of rans and dns simulation results. the cnn learned rans correction function successfully facilitates the rans uncertainty quantification ( uq ), and our findings suggest that the lightweight cnn approach is effective in combining rans and dns simulation results to enrich the existing perturbation method in estimating the rans uq more precisely. | arxiv:2301.11848 |
we propose a correspondence between brane - antibrane systems and stable triples ( e _ 1, e _ 2, t ), where e _ 1, e _ 2 are holomorphic vector bundles and the tachyon t is a map between them. we demonstrate that, under the assumption of holomorphicity, the brane - antibrane field equations reduce to a set of vortex equations, which are equivalent to the mathematical notion of stability of the triple. we discuss some examples and show that the theory of stable triples suggests a new notion of bps bound states and stability, and curious relations between brane - antibrane configurations and wrapped branes in higher dimensions. | arxiv:hep-th/0009112 |
current strategies for solving image - based inverse problems apply latent diffusion models to perform posterior sampling. however, almost all approaches make no explicit attempt to explore the solution space, instead drawing only a single sample from a gaussian distribution from which to generate their solution. in this paper, we introduce a particle - filtering - based framework for a nonlinear exploration of the solution space in the initial stages of reverse sde methods. our proposed particle - filtering - based latent diffusion ( pfld ) method and proposed problem formulation and framework can be applied to any diffusion - based solution for linear or nonlinear inverse problems. our experimental results show that pfld outperforms the sota solver psld on the ffhq - 1k and imagenet - 1k datasets on inverse problem tasks of super resolution, gaussian debluring and inpainting. | arxiv:2408.13868 |
we perform a tomographic baryon acoustic oscillations analysis using the two - point galaxy correlation function measured from the combined sample of boss dr12, which covers the redshift range of $ 0. 2 < z < 0. 75 $. splitting the sample into multiple overlapping redshift slices to extract the redshift information of galaxy clustering, we obtain a measurement of $ d _ a ( z ) / r _ d $ and $ h ( z ) r _ d $ at nine effective redshifts with the full covariance matrix calibrated using multidark - patchy mock catalogues. using the reconstructed galaxy catalogues, we obtain the precision of $ 1. 3 \ % - 2. 2 \ % $ for $ d _ a ( z ) / r _ d $ and $ 2. 1 \ % - 6. 0 \ % $ for $ h ( z ) r _ d $. to quantify the gain from the tomographic information, we compare the constraints on the cosmological parameters using our 9 - bin bao measurements, the consensus 3 - bin bao and rsd measurements at three effective redshifts in \ citet { alam2016 }, and the non - tomographic ( 1 - bin ) bao measurement at a single effective redshift. comparing the 9 - bin with 1 - bin constraint result, it can improve the dark energy figure of merit by a factor of 1. 24 for the chevallier - polarski - linder parametrisation for equation of state parameter $ w _ { \ rm de } $. the errors of $ w _ 0 $ and $ w _ a $ from 9 - bin constraints are slightly improved when compared to the 3 - bin constraint result. | arxiv:1607.03154 |
we investigate the transition of the polarized photon structure function $ g _ 1 ^ \ gamma ( x, q ^ 2, p ^ 2 ) $ when the target photon shifts from on - shell ( $ p ^ 2 = 0 $ ) to far off - shell ( $ p ^ 2 \ gg \ lambda ^ 2 $ ) region. the analysis is performed to the next - to - leading order in qcd. the first moment of $ g _ 1 ^ \ gamma $ which vanishes for the real photon, turns to be a negative value when target photon becomes off - shell. the explicit $ p ^ 2 $ - dependence of the first moment sum rule as well as of the structure function $ g _ 1 ^ \ gamma ( x, q ^ 2, p ^ 2 ) $ as a function of $ x $ is studied in the framework of the vector meson dominance model. | arxiv:hep-ph/0606267 |
automated speaker identification ( sid ) is a crucial step for the personalization of a wide range of speech - enabled services. typical sid systems use a symmetric enrollment - verification framework with a single model to derive embeddings both offline for voice profiles extracted from enrollment utterances, and online from runtime utterances. due to the distinct circumstances of enrollment and runtime, such as different computation and latency constraints, several applications would benefit from an asymmetric enrollment - verification framework that uses different models for enrollment and runtime embedding generation. to support this asymmetric sid where each of the two models can be updated independently, we propose using a lightweight neural network to map the embeddings from the two independent models to a shared speaker embedding space. our results show that this approach significantly outperforms cosine scoring in a shared speaker logit space for models that were trained with a contrastive loss on large datasets with many speaker identities. this proposed neural embedding speaker space alignment ( nessa ) combined with an asymmetric update of only one of the models delivers at least 60 % of the performance gain achieved by updating both models in the standard symmetric sid approach. | arxiv:2401.12440 |
we show that the least exponential growth of counting functions which admits uncountably many closed permutation classes lies between 2 ^ n and ( 2. 33529... ) ^ n. | arxiv:math/0307399 |
stereo images, containing left and right view images with disparity, are utilized in solving low - vision tasks recently, e. g., rain removal and super - resolution. stereo image restoration methods usually obtain better performance than monocular methods by learning the disparity between dual views either implicitly or explicitly. however, existing stereo rain removal methods still cannot make full use of the complementary information between two views, and we find it is because : 1 ) the rain streaks have more complex distributions in directions and densities, which severely damage the complementary information and pose greater challenges ; 2 ) the disparity estimation is not accurate enough due to the imperfect fusion mechanism for the features between two views. to overcome such limitations, we propose a new \ underline { stereo } \ underline { i } mage \ underline { r } ain \ underline { r } emoval method ( stereoirr ) via sufficient interaction between two views, which incorporates : 1 ) a new dual - view mutual attention ( dma ) mechanism which generates mutual attention maps by taking left and right views as key information for each other to facilitate cross - view feature fusion ; 2 ) a long - range and cross - view interaction, which is constructed with basic blocks and dual - view mutual attention, can alleviate the adverse effect of rain on complementary information to help the features of stereo images to get long - range and cross - view interaction and fusion. notably, stereoirr outperforms other related monocular and stereo image rain removal methods on several datasets. our codes and datasets will be released. | arxiv:2211.10104 |
we compare pushdown automata ( pdas for short ) against other representations. first, we show that there is a family of pdas over a unary alphabet with $ n $ states and $ p \ geq 2n + 4 $ stack symbols that accepts one single long word for which every equivalent context - free grammar needs $ \ omega ( n ^ 2 ( p - 2n - 4 ) ) $ variables. this family shows that the classical algorithm for converting a pda to an equivalent context - free grammar is optimal even when the alphabet is unary. moreover, we observe that language equivalence and parikh equivalence, which ignores the ordering between symbols, coincide for this family. we conclude that, when assuming this weaker equivalence, the conversion algorithm is also optimal. second, parikh ' s theorem motivates the comparison of pdas against finite state automata. in particular, the same family of unary pdas gives a lower bound on the number of states of every parikh - equivalent finite state automaton. finally, we look into the case of unary deterministic pdas. we show a new construction converting a unary deterministic pda into an equivalent context - free grammar that achieves best known bounds. | arxiv:1706.08315 |
in this paper we develop new extremal principles in variational analysis that deal with finite and infinite systems of convex and nonconvex sets. the results obtained, unified under the name of tangential extremal principles, combine primal and dual approaches to the study of variational systems being in fact first extremal principles applied to infinite systems of sets. the first part of the paper concerns the basic theory of tangential extremal principles while the second part presents applications to problems of semi - infinite programming and multiobjective optimization. | arxiv:1101.4178 |
linear temporal logic ( ltl ) offers a simplified way of specifying tasks for policy optimization that may otherwise be difficult to describe with scalar reward functions. however, the standard rl framework can be too myopic to find maximally ltl satisfying policies. this paper makes two contributions. first, we develop a new value - function based proxy, using a technique we call eventual discounting, under which one can find policies that satisfy the ltl specification with highest achievable probability. second, we develop a new experience replay method for generating off - policy data from on - policy rollouts via counterfactual reasoning on different ways of satisfying the ltl specification. our experiments, conducted in both discrete and continuous state - action spaces, confirm the effectiveness of our counterfactual experience replay approach. | arxiv:2303.02135 |
we propose a new type of morphological instability in the diffusion - limited growth of faceted crystals from the vapor phase that can explain the formation of thin ice plates at temperatures near - 15 c. the instability appears when the attachment kinetics for facet growth depends strongly on the morphology of the facet surface. in particular, we propose that the condensation coefficient for growth of ice prism facets increases dramatically when the width of the facet approaches atomic dimensions. this model reconciles several conflicting measurements of ice crystal growth, and makes additional predictions for future growth experiments. other faceted crystalline materials may exhibit similar morphological instabilities that promote the diffusion - limited growth of thin plate - like or needle - like crystal structures. | arxiv:cond-mat/0301341 |
integer linear programming ( ilp ) can be seen as the archetypical problem for np - complete optimization problems, and a wide range of problems in artificial intelligence are solved in practice via a translation to ilp. despite its huge range of applications, only few tractable fragments of ilp are known, probably the most prominent of which is based on the notion of total unimodularity. using entirely different techniques, we identify new tractable fragments of ilp by studying structural parameterizations of the constraint matrix within the framework of parameterized complexity. in particular, we show that ilp is fixed - parameter tractable when parameterized by the treedepth of the constraint matrix and the maximum absolute value of any coefficient occurring in the ilp instance. together with matching hardness results for the more general parameter treewidth, we give an overview of the complexity of ilp w. r. t. decompositional parameters defined on the constraint matrix. | arxiv:1809.00585 |
pairwise network models such as the gaussian graphical model ( ggm ) are a powerful and intuitive way to analyze dependencies in multivariate data. a key assumption of the ggm is that each pairwise interaction is independent of the values of all other variables. however, in psychological research this is often implausible. in this paper, we extend the ggm by allowing each pairwise interaction between two variables to be moderated by ( a subset of ) all other variables in the model, and thereby introduce a moderated network model ( mnm ). we show how to construct the mnm and propose an l1 - regularized nodewise regression approach to estimate it. we provide performance results in a simulation study and show that mnms outperform the split - sample based methods network comparison test ( nct ) and fused graphical lasso ( fgl ) in detecting moderation effects. finally, we provide a fully reproducible tutorial on how to estimate mnms with the r - package mgm and discuss possible issues with model misspecification. | arxiv:1807.02877 |
implantable retinal prostheses offer a promising solution to restore partial vision by circumventing damaged photoreceptor cells in the retina and directly stimulating the remaining functional retinal cells. however, the information transmission between the camera and retinal cells is often limited by the low resolution of the electrode array and the lack of specificity for different ganglion cell types, resulting in suboptimal stimulations. in this work, we propose to utilize normalizing flow - based conditional invertible neural networks to optimize retinal implant stimulation in an unsupervised manner. the invertibility of these networks allows us to use them as a surrogate for the computational model of the visual system, while also encoding input camera signals into optimized electrical stimuli on the electrode array. compared to other methods, such as trivial downsampling, linear models, and feed - forward convolutional neural networks, the flow - based invertible neural network and its conditional extension yield better visual reconstruction qualities w. r. t. various metrics using a physiologically validated simulation tool. | arxiv:2403.04884 |
bifurcation theory is a powerful tool for studying how the dynamics of a neural network model depends on its underlying neurophysiological parameters. however, bifurcation theory has been developed mostly for smooth dynamical systems and for continuous - time non - smooth models, which prevents us from understanding the changes of dynamics in some widely used classes of artificial neural network models. this article is an attempt to fill this gap, through the introduction of algorithms that perform a semi - analytical bifurcation analysis of a spin - glass - like neural network model with binary firing rates and discrete - time evolution. our approach is based on a numerical brute - force search of the stationary and oscillatory solutions of the spin - glass model, from which we derive analytical expressions of its bifurcation structure by means of the state - to - state transition probability matrix. the algorithms determine how the network parameters affect the degree of multistability, the emergence and the period of the neural oscillations, and the formation of symmetry - breaking in the neural populations. while this technique can be applied to networks with arbitrary ( generally asymmetric ) connectivity matrices, in particular we introduce a highly efficient algorithm for the bifurcation analysis of sparse networks. we also provide some examples of the obtained bifurcation diagrams and a python implementation of the algorithms. | arxiv:1705.05647 |
we analytically work out the orbital effects caused by a rindlertype extra - acceleration arin which naturally arises in some recent models of modified gravity at large distances. in particular, we focus on the perturbations induced by it on the two - body range { \ rho } and range - rate { \ rho } \ cdot which are commonly used in satellite and planetary investigations as primary observable quantities. the constraints obtained for arin by comparing our calculations with the currently available range and range - rate residuals for some of the major bodies of the solar system, obtained without explicitly modeling arin, are 1 - 2 \ times 10 - 13 m s - 2 ( mercury and venus ), 1 \ times 10 - 14 m s - 2 ( saturn ), 1 \ times 10 - 15 m s - 2 ( mars ), while for a terrestrial rindler acceleration we have 5 \ times 10 - 16 m s - 2 ( moon ). another approach which could be followed consists of taking into account arin in re - processing all the available data sets with accordingly modified dynamical models, and estimating a dedicated solve - for parameter explicitly accounting for it. anyway, such a method is time - consuming. a preliminary analysis likely performed in such a way by a different author yields a < = 8 \ times10 - 14 m s - 2 at mars ' distance and a < = 1 \ times10 - 14 m s - 2 at saturn ' s distance. the method adopted here can be easily and straightforwardly extended to other long - range modified models of gravity as well. | arxiv:1012.0226 |
we present results from a joint xmm - newton / nustar monitoring of the seyfert 1 ngc 4593, consisting of 5x20 ks simultaneous observations spaced by two days, performed in january 2015. the source is variable, both in flux and spectral shape, on time - scales down to a few ks and with a clear softer - when - brighter behaviour. in agreement with past observations, we find the presence of a warm absorber well described by a two - phase ionized outflow. the source exhibits a cold, narrow and constant fe k alpha line at 6. 4 kev, and a broad component is also detected. the broad - band ( 0. 3 - 79 kev ) spectrum is well described by a primary power law with gamma = 1. 6 - 1. 8 and an exponential cut - off varying from 90 ( + 40, - 20 ) kev to > 700 kev, two distinct reflection components, and a variable soft excess correlated with the primary power law. this campaign shows that probing the variability of seyfert 1 galaxies on different time - scales is of prime importance to investigate the high - energy emission of agns. | arxiv:1608.02847 |
analysis of the absorption lines in the afterglow spectrum of the gamma - ray burst grb010222 indicates that its host galaxy ( at a redshift of z = 1. 476 ) is the strongest damped lyman - alpha ( dla ) system known, having a very low metallicity and modest dust content. this conclusion is based on the detection of the red wing of lyman - alpha plus a comparison of the equivalent widths of ultraviolet mg i, mg ii, and fe ii lines with those in other dlas. the column density of h i, deduced from a fit to the wing of lyman - alpha, is ( 5 + / - 2 ) 10 ^ 22 cm ^ - 2. the ratio of the column densities of zn and cr lines suggests that the dust content in our line of sight through the galaxy is low. this could be due to either dust destruction by the ultraviolet emission of the afterglow or to an initial dust composition different to that of the diffuse interstellar material, or a combination of both. | arxiv:astro-ph/0112066 |
asymptotic safety generalizes asymptotic freedom and could contribute to understanding physics beyond the standard model. it is a candidate scenario to provide an ultraviolet extension for the effective quantum field theory of gravity through an interacting fixed point of the renormalization group. recently, asymptotic safety has been established in specific gauge - yukawa models in four dimensions in perturbation theory, providing a starting point for asymptotically safe model building. moreover, an asymptotically safe fixed point might even be induced in the standard model under the impact of quantum fluctuations of gravity in the vicinity of the planck scale. this review contains an overview of the key concepts of asymptotic safety, its application to matter and gravity models, exploring potential phenomenological implications and highlighting open questions. | arxiv:1810.07615 |
zero - field muon spin relaxation ( zf - $ \ mu $ sr ) measurements were undertaken on under - and overdoped samples of superconducting yba $ _ 2 $ cu $ _ 3 $ o $ _ { 6 + x } $ to determine the origin of the weak static magnetism recently reported in this system. the temperature dependence of the muon spin relaxation rate in overdoped crystals displays an unusual behavior in the superconducting state. a comparison to the results of nqr and lattice structure experiments on highly doped samples provides compelling evidence for strong coupling of charge, spin and structural inhomogeneities. | arxiv:cond-mat/0108479 |
an equivalent but useful version on the homological nerve theorem is proved. | arxiv:1609.03485 |
for the task of conversation emotion recognition, recent works focus on speaker relationship modeling but ignore the role of utterance ' s emotional tendency. in this paper, we propose a new expression paradigm of sentence - level emotion orientation vector to model the potential correlation of emotions between sentence vectors. based on it, we design an emotion recognition model, which extracts the sentence - level emotion orientation vectors from the language model and jointly learns from the dialogue sentiment analysis model and extracted sentence - level emotion orientation vectors to identify the speaker ' s emotional orientation during the conversation. we conduct experiments on two benchmark datasets and compare them with the five baseline models. the experimental results show that our model has better performance on all data sets. | arxiv:2106.08785 |
wikipedia has evolved beyond its original function as an online encyclopedia in an increasingly complex data - driven society. the social platform is met with a balancing act between collective intelligence and mass surveillance ; processes need to be developed to protect individuals and the community from government mass surveillance without sacrificing the important contributions made through prohibited anonymous communication software. case studies are provided from nsa government surveillance practices, the anti - sopa legislation movement, and research that covers wikipedia ' s involvement with participatory journalism, disinformation, self - censorship, and the use of tor. this paper proposes that a common ground can be developed between individuals, public and private institutions through future research in socio - cultural anthropology and policy frameworks around data retention and government accountability. wikipedia is used as an example within the us intelligence community as a complex organisation that can adapt to changes through its iterative nature, which draws insight into how policy frameworks can be future - proofed. finally, this paper is a wake - up call to individuals, private institutions, and governments to remain vigilant about the storage and use of personal information as a result of contributing to online communities. | arxiv:2212.05828 |
we present a detailed abundance analysis based on high resolution and high signal - to - noise spectra of eight extremely metal poor ( emp ) stars with [ fe / h ] < - 3. 5 $ dex, four of which are new. only stars with 4900 < teff < 5650 k are included. two stars of the eight are outliers in each of several abundance ratios. the most metal poor star in this sample, he1424 - 0241, has [ fe / h ] ~ - 4 dex and is thus among the most metal poor stars known in the galaxy. it has highly anomalous abundance ratios unlike those of any other known emp giant, with very low si, ca and ti relative to fe, and enhanced mn and co, again relative to fe. only ( low ) upper limits for c and n can be derived from the non - detection of the ch and nh molecular bands. he0132 $ - $ 2429, another sample star, has excesses of n and sc with respect to fe. the strong outliers in abundance ratios among the fe - peak elements in these c - normal stars, not found at somewhat higher metallicities, are definitely real. they suggest that at such low metallicities we are beginning to see the anticipated and long sought stochastic effects of individual supernova events contributing to the fe - peak material within a single star. a detailed comparison of the results of the analysis procedures adopted by our 0z project compared to those of the first stars vlt large project finds a systematic difference for [ fe / h ] of ~ 0. 3 dex, our values always being higher. | arxiv:0709.0029 |
we present an automated statistical method that uses medium - resolution spectroscopic observations of a set of stars to select those that show evidence of possessing significant amounts of neutron - capture elements. our tool was tested against a sample of $ \ sim 70, 000 $ f - and g - type stars distributed among $ 215 $ plates from the galactic understanding and exploration ( segue ) survey, including $ 13 $ that were directed at stellar galaxy clusters. focusing on five spectral lines of europium in the visible window, our procedure ranked the stars by their likelihood of having enhanced content of this atomic species and identifies the objects that exhibit signs of being rich in neutron - capture elements as those scoring in the upper $ 2. 5 \ % $. we find that several of the cluster plates contain relatively large numbers of stars with significant absorption around at least three of the five selected lines. the most prominent is the globular cluster m3, where we measured a fraction of stars that are potentially rich in heavy nuclides, representing at least $ 15 \ % $. | arxiv:1909.11463 |
this thesis consists of three closely related parts. an analysis of data recorded by the atlas detector in 2010 in proton - proton collisions at a center - of - mass energy of 7 tev with an integrated luminosity of 33. 4 / pb is performed, searching for supersymmetric final states containing jets and missing transverse energy and no electrons or muons ( zero - lepton channel ). no excess over the standard model background expectation is observed. using the cls and plr methods, exclusion limits are set in two different supergravity models. these considerably extend the excluded parameter ranges from earlier experiments. the rates and efficiencies of triggers based on combined signatures with jets plus missing transverse energy in atlas are studied, which are the primary triggers for the search for supersymmetry in the zero - lepton channel. for the measurement of the efficiencies in data collected in 2010 and 2011, the bootstrap method is applied. different sample triggers based on jets and missing transverse energy are compared and their efficiencies are measured. a reweighting approach is used to correct for the bias from the propagation of the uncertainties in the bootstrap method. a universal model is developed to describe the contribution of fake missing transverse energy from resolution effects to the rates of missing transverse energy triggers as function of the level of in - time pile - up, i. e. the number of concurrent proton - proton interactions. the input parameters are tuned to the properties of the atlas trigger system, and the model predictions are compared to measurements of trigger rates in atlas. good agreement is found for low thresholds for which the rates are dominated by resolution effects, whereas the rates for higher thresholds are underestimated due to additional sources of fake and real missing transverse energy, which are not incorporated in the model. | arxiv:1205.5169 |
we investigate the dephasing of ultra cold ^ { 85 } rb atoms trapped in an optical dipole trap and prepared in a coherent superposition of their two hyperfine ground states by interaction with a microwave pulse. we demonstrate that the dephasing, measured as the ramsey fringe contrast, can be reversed by stimulating a coherence echo with a pi - pulse between the two pi / 2 pulses, in analogy to the photon echo. we also demonstrate that the failure of the echo for certain trap parameters is due to dynamics in the trap, and thereby that ' ' echo spectroscopy ' ' can be used to study the quantum dynamics in the trap even when more than 10 ^ 6 states are thermally populated, and to study the crossover from quantum ( where dynamical decoherence is supressed ) to classical dynamics. | arxiv:quant-ph/0208052 |
volcanic tremor is key to our understanding of active magmatic systems but, due to its complexity, there is still a debate concerning its origins and how it can be used to characterize eruptive dynamics. in this study we leverage machine learning ( ml ) techniques using 6 years of continuous seismic data from the piton de la fournaise volcano ( la r \ ' eunion island ) to describe specific patterns of seismic signals recorded during eruptions. these results unveil what we interpret as signals associated with various eruptive dynamics of the volcano, including the effusion of a large volume of lava during the august - october 2015 eruption, as well as the closing of the eruptive vent during the september - november 2018 eruption. the ml workflow we describe can easily be applied to other active volcanoes, potentially leading to an enhanced understanding of the temporal and spatial evolution of volcanic eruptiions | arxiv:1909.12395 |
recent advances in deep learning architectures for sequence modeling have not fully transferred to tasks handling time - series from electronic health records. in particular, in problems related to the intensive care unit ( icu ), the state - of - the - art remains to tackle sequence classification in a tabular manner with tree - based methods. recent findings in deep learning for tabular data are now surpassing these classical methods by better handling the severe heterogeneity of data input features. given the similar level of feature heterogeneity exhibited by icu time - series and motivated by these findings, we explore these novel methods ' impact on clinical sequence modeling tasks. by jointly using such advances in deep learning for tabular data, our primary objective is to underscore the importance of step - wise embeddings in time - series modeling, which remain unexplored in machine learning methods for clinical data. on a variety of clinically relevant tasks from two large - scale icu datasets, mimic - iii and hirid, our work provides an exhaustive analysis of state - of - the - art methods for tabular time - series as time - step embedding models, showing overall performance improvement. in particular, we evidence the importance of feature grouping in clinical time - series, with significant performance gains when considering features within predefined semantic groups in the step - wise embedding module. | arxiv:2311.08902 |
we study spatially flat isotropic universes driven by k - essence. it is shown that friedmann and k - field equations may be analytically integrated for arbitrary k - field potentials during evolution with a constant baryotropic index. it follows that there is an infinite number of dynamically different k - theories with equivalent kinematics of the gravitational field. we show that there is a large " window " of stable solutions, and that the dust - like behaviour separates stable from unstable expansion. restricting to the family of power law solutions, it is argued that the linear scalar field model, with constant function f, is isomorphic to a model with divergent speed of sound and this makes them less suitable for cosmological modeling than the non - linear k - field solutions we find in this paper. | arxiv:astro-ph/0305007 |
we examine two proposals for marginally self - correcting quantum memory, the cubic code by haah and the welded code by michnicki. in particular, we prove explicitly that they are absent of topological order above zero temperature, as their gibbs ensembles can be prepared via a short - depth quantum circuit from classical ensembles. our proof technique naturally gives rise to the notion of free energy associated with excitations. further, we develop a framework for an ergodic decomposition of davies generators in css codes which enables formal reduction to simpler classical memory problems. we then show that memory time in the welded code is doubly exponential in inverse temperature via the peierls argument. these results introduce further connections between thermal topological order and self - correction from the viewpoint of free energy and quantum circuit depth. | arxiv:1603.07805 |
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