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while the empirical success of self - supervised learning ( ssl ) heavily relies on the usage of deep nonlinear models, existing theoretical works on ssl understanding still focus on linear ones. in this paper, we study the role of nonlinearity in the training dynamics of contrastive learning ( cl ) on one and two - layer nonlinear networks with homogeneous activation $ h ( x ) = h ' ( x ) x $. we have two major theoretical discoveries. first, the presence of nonlinearity can lead to many local optima even in 1 - layer setting, each corresponding to certain patterns from the data distribution, while with linear activation, only one major pattern can be learned. this suggests that models with lots of parameters can be regarded as a \ emph { brute - force } way to find these local optima induced by nonlinearity. second, in the 2 - layer case, linear activation is proven not capable of learning specialized weights into diverse patterns, demonstrating the importance of nonlinearity. in addition, for 2 - layer setting, we also discover \ emph { global modulation } : those local patterns discriminative from the perspective of global - level patterns are prioritized to learn, further characterizing the learning process. simulation verifies our theoretical findings.
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arxiv:2206.01342
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the use of multi - chip modules ( mcm ) and / or multi - socket boards is the most suitable approach to increase the computation density of servers while keep chip yield attained. this paper introduces a new coherence protocol suitable, in terms of complexity and scalability, for this class of systems. the proposal uses two complementary ideas : ( 1 ) a mechanism that dissociates complexity from performance by means of colored - token counting, ( 2 ) a construct that optimizes performance and cost by means of two functionally symmetrical modules working in the last level cache of each chip ( d | f - llc ) and each memory controller ( d | f - mem ). each of these structures is divided into two parts : ( 2. 1 ) the first one consists of a small loosely inclusive sparse directory where only the most actively shared data are tracked in the chip ( d - llc ) from each memory controller ( d - mem ) and, ( 2. 2 ) the second is a d - left counting bloom filter which stores approximate information about the blocks allocated, either inside the chip ( f - llc ) or in the home memory controller ( f - mem ). the coordinated work of both structures minimizes the coherence - related effects on the average memory latency perceived by the processor. our proposal is able to improve on the performance of a hypertransport - like coherence protocol by from 25 % - to - 60 %.
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arxiv:2002.03944
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recently, inspired by the concept of sparsity, mixture - of - experts ( moe ) models have gained increasing popularity for scaling model size while keeping the number of activated parameters constant. in this study, we thoroughly investigate the sparsity of the dense llama model by constructing moe for both the attention ( i. e., attention moe ) and mlp ( i. e., mlp moe ) modules in the transformer blocks. specifically, we investigate different expert construction methods and granularities under the same activation conditions to analyze the impact of sparsifying the model. additionally, to comprehensively evaluate the model ' s capabilities across various domains ( e. g., conversation, code, math ) after sparsification, we apply sparsity to the instructed large language models ( llms ) and construct instructed moe models. to counteract the performance degradation resulting from increased sparsity, we design a two - stage post - training strategy to enhance model performance. experiments on the llama3 model demonstrate the potential effectiveness of this approach for future developments of instructed moe models. the source codes and models are available at : \ url { https : / / github. com / opensparsellms / llama - moe - v2 }.
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arxiv:2411.15708
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dark matter - deficient galaxies ( dmdgs ) discovered in the survey of ultra - diffuse galaxies ( udgs ), in apparent conflict with standard cdm, may be produced by high - velocity galaxy - galaxy collisions, the $ \ textit { mini - bullet } $ scenario. recent observations of an aligned trail of $ 7 - 11 $ udgs near ngc1052, including dmdgs df2 and df4, suggesting a common formation event, $ \ sim8. 9 \ pm1. 5 $ gyr ago, provide a test. hydro / n - body simulations, supplemented by galaxy orbit integrations, demonstrate that satellite - satellite collisions outside the host - galaxy virial radius can reproduce the observed udgs in the ngc1052 group. a trail of $ \ sim10 $ dmdgs is shown to form, including two massive ones that replicate the observed motions of df2 and df4. the linear relation, $ v = ax + v _ { 0 } $, conjectured previously to relate positions ( $ x $ ) and velocities ( $ v $ ) of the aligned dmdgs as a signature of the collision event, is approximately obeyed, but individual dmdgs can deviate significantly from it. the progenitors whose collision spawned the trail of dmdgs survive the collision without, themselves, becoming dmdgs. we predict one progenitor is located at the end of the trail, testable by observing the difference between its stars, formed pre - collision, from those of the dmdgs, formed post - collision. by contrast, stellar ages and metallicities of the dmdgs are nearly identical. we further offer a hint that the tidal field of host ngc1052 may contribute to making dmdgs diffuse. $ \ lambda $ cdm simulation in a 100 cmpc box finds our required initial conditions $ \ sim10 $ times at $ z < 3 $. these results indicate current observations are consistent with the $ \ textit { mini - bullet } $ scenario.
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arxiv:2312.11350
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we describe and analyze hubble space telescope ( hst ) observations of transient emission near 4680 { \ aa } in eta car, reported earlier by steiner & damineli ( 2004 ). if, as seems probable, this is he ii $ \ lambda $ 4687, then it is a unique clue to eta car ' s 5. 5 - year cycle. according to our analysis, several aspects of this feature support a mass - ejection model of the observed spectroscopic events, and not an eclipse model. the he ii emission appeared in early 2003, grew to a brief maximum during the 2003. 5 spectroscopic event, and then abruptly disappeared. it did not appear in any other hst spectra before or after the event. the peak brightness was larger than previously reported, and is difficult to explain even if one allows for an uncertainty factor of order 3. the stellar wind must provide a temporary larger - than - normal energy supply, and we describe a special form of radiative amplification that may also be needed. these characteristics are consistent with a class of mass - ejection or wind - disturbance scenarios, which have implications for the physical structure and stability of eta car.
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arxiv:astro-ph/0504151
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we discuss isometric embedding diagrams for the visualization of initial data for the problem of the head - on collision of two black holes. the problem of constructing the embedding diagrams is explicitly presented for the best studied initial data, the misner geometry. we present a partial solution of the embedding diagrams and discuss issues related to completing the solution.
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arxiv:gr-qc/9409047
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a fundamental result in cake cutting states that for any number of players with arbitrary preferences over a cake, there exists a division of the cake such that every player receives a single contiguous piece and no player is left envious. we generalize this result by showing that it is possible to partition the players into groups of any desired sizes and divide the cake among the groups, so that each group receives a single contiguous piece and no player finds the piece of another group better than that of the player ' s own group.
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arxiv:2001.03327
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the conductivity of graphene samples with various levels of disorder is investigated for a set of specimens with mobility in the range of $ 1 - 20 \ times10 ^ 3 $ cm $ ^ 2 $ / v sec. comparing the experimental data with the theoretical transport calculations based on charged impurity scattering, we estimate that the impurity concentration in the samples varies from $ 2 - 15 \ times 10 ^ { 11 } $ cm $ ^ { - 2 } $. in the low carrier density limit, the conductivity exhibits values in the range of $ 2 - 12e ^ 2 / h $, which can be related to the residual density induced by the inhomogeneous charge distribution in the samples. the shape of the conductivity curves indicates that high mobility samples contain some short range disorder whereas low mobility samples are dominated by long range scatterers.
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arxiv:0707.1807
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we propose predictive models that estimate gbm patients ' health status of one - year after treatments ( classification task ), predict the long - term prognosis of gbm patients at an individual level ( survival task ). we used total of 467 gbm patients ' clinical profile consists of 13 features and two follow - up dates. for baseline models of random forest classifier ( rfc ) and random survival forest model ( rsf ), we introduced generalized linear model ( glm ), support vector machine ( svm ) and cox proportional hazardous model ( cox ), accelerated failure time model ( aft ) respectively. after preprocessing and prefixing stratified 5 - fold data set, we generated best performing models for model types using recursive feature elimination process. total 10, 4, and 13 features were extracted for best performing one - year survival / progression status rfc models and rsf model via the recursive feature elimination process. in classification task, auroc of best performing rfc recorded 0. 6990 ( for one - year survival status classification ) and 0. 7076 ( for one - year progression classification ) while that of second best baseline models ( glm in both cases ) recorded 0. 6691 and 0. 6997 respectively. about survival task, the highest c - index of 0. 7157 and the lowest ibs of 0. 1038 came from the best performing rsf model while that of second best baseline models were 0. 6556 and 0. 1139 respectively. a simplified linear correlation ( extracted from lime and virtual patient group analysis ) between each feature and prognosis of gbm patient were consistent with proven medical knowledge. our machine learning models suggest that the top three prognostic factors for gbm patient survival were mgmt gene promoter, the extent of resection, and age. to the best of our knowledge, this study is the very first study introducing a interpretable and medical knowledge consistent gbm prognosis predictive models.
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arxiv:2108.13039
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to learn quantum mechanics, one must become adept in the use of various mathematical structures that make up the theory ; one must also become familiar with some basic laboratory experiments that the theory is designed to explain. the laboratory ideas are naturally expressed in one language, and the theoretical ideas in another. we present a method for learning quantum mechanics that begins with a laboratory language for the description and simulation of simple but essential laboratory experiments, so that students can gain some intuition about the phenomena that a theory of quantum mechanics needs to explain. then, in parallel with the introduction of the mathematical framework on which quantum mechanics is based, we introduce a calculational language for describing important mathematical objects and operations, allowing students to do calculations in quantum mechanics, including calculations that cannot be done by hand. finally, we ask students to use the calculational language to implement a simplified version of the laboratory language, bringing together the theoretical and laboratory ideas.
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arxiv:1611.09471
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the aftermath of influenza infection is determined by a complex set of host - pathogen interactions, where genomic variability on both viral and host sides influences the final outcome. although there exists large body of literature describing influenza virus variability, only a very small fraction covers the issue of host variance. the goal of this review is to explore the variability of host genes responsible for host - pathogen interactions, paying particular attention to genes responsible for the presence of sialylated glycans in the host endothelial membrane, mucus, genes used by viral immune escape mechanisms, and genes particularly expressed after vaccination, since they are more likely to have a direct influence on the infection outcome.
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arxiv:1409.2031
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in the framework of the hartle - hawking no - boundary proposal, we investigate quantum creation of the multidimensional universe with the cosmological constant $ \ lambda $ but without matter fields. in this paper we solved the wheeler - de witt equation numerically. we find that the universe in which both of the spaces expand exponentially is the most probable in this model.
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arxiv:gr-qc/0007060
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in this survey, we review the classical hamilton jacobi theory from a geometric point of view in different geometric backgrounds. we propose a hamilton jacobi equation for different geometric structures attending to one particular characterization : whether they fulfill the jacobi and leibniz identities simultaneously, or if at least they satisfy one of them. in this regard, we review the case of time dependent and dissipative physical systems as systems that fulfill the jacobi identity but not the leibnitz identity. furthermore, we review the contact evolution hamilton jacobi theory as a split off the regular contact geometry, and that actually satisfies the leibniz rule instead of jacobi. furthermore, we include a novel result, which is the hamilton - jacobi equation for conformal hamiltonian vector fields as a generalization of the well known hamilton jacobi on a symplectic manifold, that is retrieved in the case of a zero conformal factor. the interest of a geometric hamilton jacobi equation is the primordial observation that if a hamiltonian vector field can be projected into a configuration manifold by means of a 1 - form dw, then the integral curves of the projected vector field can be transformed into integral curves of the hamiltonian vector field provided that w is a solution of the hamilton - jacobi equation. geometrically, the solution of the hamilton jacobi equation plays the role of a lagrangian submanifold of a certain bundle. exploiting these features in different geometric scenarios we propose a geometric theory for multiple physical systems depending on the fundamental identities that their dynamic satisfies. different examples are pictured to reflect the results provided, being all of them new, except for one that is reassessment of a previously considered example.
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arxiv:2202.06896
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recently the cms collaboration at the lhc reported " the first direct limit on black hole production at a particle accelerator " using a data sample corresponding to an integrated luminosity of 35 / pb of pp - collision at a center of mass energy of 7 tev. even though the result has a strong impact on future searches, the interpretation lacks enough theoretical support. in this letter, we show that the parameter range which was considered by the cms collaboration is actually out of the validity range of semi - classical black hole picture so that the monte - carlo simulation result which was crucially used in the analysis still needs further solid scientific basis.
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arxiv:1104.5129
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the novel pq mechanism replaces the strong cp problem with some challenges in a model building. in particular, the challenges arise regarding i ) the origin of an anomalous global symmetry called a pq symmetry, ii ) the scale of the pq symmetry breaking, and iii ) the quality of the pq symmetry. in this letter, we provide a natural and simple uv completed model that addresses these challenges. extra quarks and anti - quarks are separated by two branes in the randall - sundrum $ { \ bf r } ^ 4 \ times s ^ 1 / { \ bf z } _ 2 $ spacetime while a hidden su ( $ n _ h $ ) gauge field condensates in the bulk. the brane separation is the origin of the pq symmetry and its breaking scale is given by the dynamical scale of the su ( $ n _ h $ ) gauge interaction. the ( generalized ) casimir force of su ( $ n _ h $ ) condensation stabilizes the 5th dimension, which guarantees the quality of the pq symmetry.
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arxiv:2101.10350
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we perform a systematic study of the multi - wavelength signal induced by weakly interacting massive particle ( wimp ) annihilations at the galactic center ( gc ). referring to a generic wimp dark matter ( dm ) scenario and depending on astrophysical inputs, we discuss spectral and angular features and sketch correlations among signals in the different energy bands. none of the components which have been associated to the gc source sgr a *, nor the diffuse emission components from the gc region, have spectral or angular features typical of a dm source. still, data - sets at all energy bands, namely, the radio, near infrared, x - ray and gamma - ray bands, contribute to place significant constraints on the wimp parameter space. in general, the gamma - ray energy range is not the one with the largest signal to background ratio. in the case of large magnetic fields close to the gc, x - ray data give the tightest bounds. the emission in the radio - band, which is less model dependent, is very constraining as well. the recent detection by hess of a gc gamma - ray source, and of a diffuse gamma - ray component, limits the possibility of a dm discovery with next generation of gamma - ray telescopes, like glast and cta. we find that the most of the region in the parameter space accessible to these instruments is actually already excluded at other wave - lenghts. on the other hand, there may be still an open window to improve constraints with wide - field radio observations.
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arxiv:0802.0234
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we study deterministic discrete time exclusion type spatially heterogeneous particle processes in continuum. a typical example of this sort is a traffic flow model with obstacles : traffic lights, speed bumps, spatially varying local velocities etc. ergodic averages of particle velocities are obtained and their connections to other statistical quantities, in particular to particle and obstacles densities ( the so called fundamental diagram ) is analyzed rigorously. the main technical tool is a " dynamical " coupling construction applied in a nonstandard fashion : instead of proving the existence of the successful coupling ( which even might not hold ) we use its presence / absence as an important diagnostic tool.
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arxiv:1105.4232
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current sheets ( css ) are preferred sites of magnetic reconnection and energy dissipation in collisionless astrophysical plasmas. electric currents in them may be carried by both electrons and ions. in our prior theoretical studies of processes associated with the cs formation in turbulent plasmas, for which we utilized fully kinetic and hybrid code simulations with ions considered as particles and electrons - as a massless fluid, we found that electron - dominated css may form inside or nearby ion - dominated css. electrons become the main carrier of the electric current and contributors to energy dissipation in electron - dominated css. these magneto - plasma structures represent a distinguished type of css and should not be mixed up with so - called electron - scale css. our simulations show that such css are characterized by the electron - to - ion bulk speed ratio ue / ui increases. theoretical predictions and high - resolution observations from the mms mission suggest that strong electron - dominated css can be seen at ion scales. therefore, we suggest that applying the ue / ui parameter to the solar wind data may allow locating the strongest electron - dominated css with an ordinary spacecraft resolution of one - three seconds at least approximately. the results show that, indeed, an impact of electron - dominated css on the plasma observed during a period of quiet solar wind conditions at 1 au may be associated with sharp changes in ue / ui. electron - dominated css are found to be localized in the vicinity of ion - dominated css identified via changes in the magnetic field and plasma parameters ue / ui, displaying the same clustering. we conclude that ue / ui may be used as one of key parameters for probing css in the solar wind and the role of electrons in them.
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arxiv:2112.03639
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could it be that the matter from the electrons in high tc superconductors is of a radically new kind that may be called " many body entangled compressible quantum matter "? much of this text is intended as an easy to read tutorial, explaining recent theoretical advances that have been unfolding at the cross roads of condensed matter - and string theory, black hole physics as well as quantum information theory. these developments suggest that the physics of such matter may be governed by surprisingly simple principles. my real objective is to present an experimental strategy to test critically whether these principles are actually at work, revolving around the famous linear resistivity characterizing the strange metal phase. the theory suggests a very simple explanation of this " unreasonably simple " behavior that is actually directly linked to remarkable results from the study of the quark gluon plasma formed at the heavy ion colliders : the " fast hydrodynamization " and the " minimal viscosity ". this leads to high quality predictions for experiment : the momentum relaxation rate governing the resistivity relates directly to the electronic entropy, while at low temperatures the electron fluid should become unviscous to a degree that turbulent flows can develop even on the nanometre scale.
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arxiv:1807.10951
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the axion is a highly motivated elementary particle which could address two fundamental questions in physics - the strong cp problem and the dark matter mystery. experimental searches for this hypothetical particle have started to reach theoretically interesting sensitivity levels, particularly in the $ \ mu $ ev ( ghz ) region. they rely on large volume solenoid magnetic fields and microwave resonators with signals read out by quantum noise limited amplifiers. concurrently, there have been intensive experimental efforts to widen the search range by devising various techniques as well as to enhance sensitivities by implementing advanced technologies. the developments and improvements in these orthogonal approaches will enable us to explore most of the parameter space of the axion and axion - like particles within the next couple of decades, with the 1 - 25 ghz frequency range to be conquered well within the first decade. we review the experimental aspects of axion physics and discuss the past, present and future of the direct search programs.
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arxiv:2104.14831
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we present a novel approach to the problem of dual - functional radar and communication ( dfrc ) waveform design with adjustable peak - to - average power ratio ( papr ), while minimizing the multi - user communication interference and maintaining a similarity constraint towards a radar chirp signal. the approach is applicable to generic radar chirp signals and for different constellation sizes. we formulate the waveform design problem as a non convex optimization problem. as a solution, we adopt the alternating direction method of multipliers ( admm ), hence iterating towards a stable waveform for both radar and communication purposes. additionally, we prove convergence of the proposed method and analyze its computational complexity. moreover, we offer an extended version of the method to cope with imperfect channel state information ( csi ). finally, we demonstrate its superior performance through simulations, in comparison to state - of - the - art radar - communication waveform designs.
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arxiv:2210.02892
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in this note let us give two remarks on proof - theory of pa. first a derivability relation is introduced to bound witnesses for provable $ \ sigma _ { 1 } $ - formulas in pa. second paris - harrington ' s proof for their independence result is reformulated to show a ` consistency ' proof of pa based on a combinatorial principle.
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arxiv:2003.13207
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a search for the decays bs - > mumu and bd - > mumu is performed with about 37 pb - 1 of pp collisions at \ sqrt ( s ) = 7 tev collected by the lhcb experiment at the large hadron collider at cern. the observed numbers of events are consistent with the background expectations. the resulting upper limits on the branching fractions are br ( bs - > mumu ) < 5. 6 * 10 ^ { - 8 } and b ( bd - > mumu ) < 1. 5 * 10 ^ { - 8 } at 95 % confidence level.
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arxiv:1106.2087
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we searched up to height $ 10 ^ 7 $ for rational points on diagonal quartic surfaces. the computations fill several gaps in earlier lists computed by pinch, swinnerton - dyer, and bright.
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arxiv:1008.3275
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homomorphic encryption aims at allowing computations on encrypted data without decryption other than that of the final result. this could provide an elegant solution to the issue of privacy preservation in data - based applications, such as those using machine learning, but several open issues hamper this plan. in this work we assess the possibility for homomorphic encryption to fully implement its program without relying on other techniques, such as multiparty computation ( smpc ), which may be impossible in many use cases ( for instance due to the high level of communication required ). we proceed in two steps : i ) on the basis of the structured program theorem ( bohm - jacopini theorem ) we identify the relevant minimal set of operations homomorphic encryption must be able to perform to implement any algorithm ; and ii ) we analyse the possibility to solve - - and propose an implementation for - - the most fundamentally relevant issue as it emerges from our analysis, that is, the implementation of conditionals ( requiring comparison and selection / jump operations ). we show how this issue clashes with the fundamental requirements of homomorphic encryption and could represent a drawback for its use as a complete solution for privacy preservation in data - based applications, in particular machine learning ones. our approach for comparisons is novel and entirely embedded in homomorphic encryption, while previous studies relied on other techniques, such as smpc, demanding high level of communication among parties, and decryption of intermediate results from data - owners. our protocol is also provably safe ( sharing the same safety as the homomorphic encryption schemes ), differently from other techniques such as order - preserving / revealing - encryption ( ope / ore ).
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arxiv:1810.12380
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by suitably generalizing the fourier constraint projection in the difference map phasing algorithm, an object can be reconstructed from its diffraction pattern even when the latter has been incoherently averaged over a discrete group of symmetries. this resolves an ambiguity in the recent proposal for aligning molecules by means of their anisotropic dielectric interaction with an intense light field. the algorithm is demonstrated with simulated data in two and three dimensions.
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arxiv:physics/0505174
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^ \ mathbb { n } $, $ p _ { \ mathbb { n } } $, and inj $ ( \ mathbb { n } ) $ coincide with the pointwise topology ; and we characterise the zariski topology on $ b _ { \ mathbb { n } } $. in section 7 : clones.
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arxiv:1912.07029
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efficient design and performance of electrically actuated mems devices necessitate accurate estimation of electrostatic forces on the mems structures. this in turn requires thorough study of the capacitance of the structures and finally the charge density distribution on the various surfaces of a device. in this work, nearly exact bem solutions have been provided in order to estimate these properties of a parallel narrow beam structure found in mems devices. the effect of three - dimensionality, which is an important aspect for these structures, and associated fringe fields have been studied in detail. a reasonably large parameter space has been covered in order to follow the variation of capacitance with various geometric factors. the present results have been compared with those obtained using empirical parametrized expressions keeping in view the requirement of the speed of computation. the limitations of the empirical expressions have been pointed out and possible approaches of their improvement have been discussed.
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arxiv:physics/0703060
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minimizing the number of dropped user datagram protocol ( udp ) messages in a network is regarded as a challenge by researchers. this issue represents serious problems for many protocols particularly those that depend on sending messages as part of their strategy, such us service discovery protocols. this paper proposes and evaluates an algorithm to predict the minimum period of time required between two or more consecutive messages and suggests the minimum queue sizes for the routers, to manage the traffic and minimise the number of dropped messages that has been caused by either congestion or queue overflow or both together. the algorithm has been applied to the universal plug and play ( upnp ) protocol using ns2 simulator. it was tested when the routers were connected in two configurations ; as a centralized and de centralized. the message length and bandwidth of the links among the routers were taken in the consideration. the result shows better improvement in number of dropped messages ` among the routers.
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arxiv:1112.2408
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we study the phase behaviour of the zwanzig model of suspensions of hard rods, allowing for polydispersity in the lengths of the rods. in spite of the simplified nature of the model ( rods are restricted to lie along one of three orthogonal axes ), the results agree qualitatively with experimental observations : the coexistence region broadens significantly as the polydispersity increases, and strong fractionation occurs, with long rods found preferentially in the nematic phase. these conclusions are obtained from an analysis of the exact phase equilibrium equations. in the second part of the paper, we consider the application of the recently developed ` ` moment free energy method ' ' to the polydisperse zwanzig model. even though the model contains non - conserved densities due to the orientational degrees of freedom, most of the exactness statements ( regarding the onset of phase coexistence, spinodals, and critical points ) derived previously for systems with conserved densities remain valid. the accuracy of the results from the moment free energy increases as more and more additional moments are retained in the description. we show how this increase in accuracy can be monitored without relying on knowledge of the exact results, and discuss an adaptive technique for choosing the extra moments optimally.
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arxiv:cond-mat/0005321
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in the early days of the web, giving the same web page to different browsers could provide very different results. as the rendering engine behind each browser would differ, some elements of a page could break or be positioned in the wrong location. at that time, the user agent ( ua ) string was introduced for content negotiation. by knowing the browser used to connect to the server, a developer could provide a web page that was tailored for that specific browser to remove any usability problems. over the past three decades, the ua string remained exposed by browsers, but its current usefulness is being debated. browsers now adopt the exact same standards and use the same languages to display the same content to users, bringing the question if the content of the ua string is still relevant today, or if it is a relic of the past. moreover, the diversity of means to browse the web has become so large that the ua string is one of the top contributors to tracking users in the field of browser fingerprinting, bringing a sense of urgency to deprecate it. in this paper, our goal is to understand the impact of the ua on the web and if this legacy string is still actively used to adapt the content served to users. we introduce ua - radar, a web page similarity measurement tool that compares in - depth two web pages from the code to their actual rendering, and highlights the similarities it finds. we crawled 270, 048 web pages from 11, 252 domains using 3 different browsers and 2 different ua strings to observe that 100 % of the web pages were similar before any javascript was executed, demonstrating the absence of differential serving. our experiments also show that only a very small number of websites are affected by the lack of ua information, which can be fixed in most cases by updating code to become browser - agnostic. our study brings some proof that it may be time to turn the page on the ua string and retire it from current web browsers.
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arxiv:2311.10420
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we explore the relationship between x - ray absorption and optical obscuration within the bat agn spectroscopic survey ( bass ) which has been collecting and analyzing the optical and x - ray spectra for 641 hard x - ray selected ( $ e > 14 $ kev ) active galactic nuclei ( agn ). we use the deviation from a linear broad h $ \ alpha $ - to - x - ray relationship as an estimate of the maximum optical obscuration towards the broad line region and compare the $ a _ { \ rm v } $ to the hydrogen column densities ( $ n _ { \ rm h } $ ) found through systematic modeling of their x - ray spectra. we find that the inferred columns implied by $ a _ { \ rm v } $ towards the broad line region ( blr ) are often orders of magnitude less than the columns measured towards the x - ray emitting region indicating a small scale origin for the x - ray absorbing gas. after removing 30 \ % of sy 1. 9s that potentially have been misclassified due to outflows, we find that 86 \ % ( 164 / 190 ) of the type 1 population ( sy 1 - - 1. 9 ) are x - ray unabsorbed as expected based on a single obscuring structure. however, 14 \ % ( 26 / 190 ), of which 70 \ % ( 18 / 26 ) are classified as sy 1. 9, are x - ray absorbed, suggesting the broad line region itself is providing extra obscuration towards the x - ray corona. the fraction of x - ray absorbed type 1 agn remains relatively constant with agn luminosity and eddington ratio, indicating a stable broad line region covering fraction.
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arxiv:1710.09117
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we propose that superluminous transients that appear at central regions of active galactic nuclei ( agns ) such as css100217 : 102913 + 404220 ( css100217 ) and ps16dtm, which reach near or super - eddington luminosities of the central black holes, are powered by the interaction between accretion disk winds and clouds in broad - line regions ( blrs ) surrounding them. if the disk luminosity temporary increases by, e. g., limit - cycle oscillations, leading to a powerful radiatively driven wind, strong shock waves propagate in the blr. because the dense clouds in the agn blrs typically have similar densities to those found in type iin supernovae, strong radiative shocks emerge and efficiently convert the ejecta kinetic energy to radiation. as a result, transients similar to type iin supernovae can be observed at agn central regions. since a typical black - hole disk wind velocity is ~ 0. 1c where c is the speed of light, the ejecta kinetic energy is expected to be ~ 1e52 erg when ~ 1 msun is ejected. this kinetic energy is transformed to radiation energy in a timescale for the wind to sweep up a similar mass to itself in the blr, which is a few hundred days. therefore, both luminosities ( ~ 1e44 erg / s ) and timescales ( ~ 100 days ) of the superluminous transients from agn central regions match to those expected in our interaction model. if css100217 and ps16dtm are related to the agn activities triggered by limit - cycle oscillations, they become bright again in coming years or decades.
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arxiv:1706.06855
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we propose a classification of the solutions of the graded reflection equations to the $ u _ { q } [ spo ( 2n | 2m ) ] $ vertex model. we find twelve distinct classes of reflection matrices such that four of them are diagonal. in the non - diagonal matrices the number of free parameters depending on the number of bosonic ( $ 2n $ ) and fermionic ( $ 2m $ ) degrees of freedom while in the diagonal ones we find solutions with at most one free parameter.
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arxiv:0810.1766
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we review the analytic results for the phase shifts delta _ { l } ( k ) in non - relativistic scattering from a spherical well. the conditions for the existence of resonances are established in terms of time - delays. resonances are shown to exist for p - waves ( and higher angular momenta ) but not for s - waves. these resonances occur when the potential is not quite strong enough to support a bound p - wave of zero energy. we then examine relativistic scattering by spherical wells and barriers in the dirac equation. in contrast to the non - relativistic situation, s - waves are now seen to possess resonances in scattering from both wells and barriers. when s - wave resonances occur for scattering from a well, the potential is not quite strong enough to support a zero momentum s - wave solution at e = m. resonances resulting from scattering from a barrier can be explained in terms of the ` crossing ' theorem linking s - wave scattering from barriers to p - wave scattering from wells. a numerical procedure to extract phase shifts for general short range potentials is introduced and illustrated by considering relativistic scattering from a gaussian potential well and barrier.
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arxiv:math-ph/0401015
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we investigate the theoretical nonlinear response, hessian stability, and possible wrinkling behaviour of a voltage - activated dielectric plate immersed in a tank filled with silicone oil. fixed rigid electrodes are placed on the top and bottom of the tank, and an electric field is generated by a potential difference between the electrodes. we solve the associated incremental boundary value problem of superimposed, inhomogeneous small - amplitude wrinkles, signalling the onset of instability. we decouple the resulting bifurcation equation into symmetric and antisymmetric modes. for a neo - hookean dielectric plate, we show that a potential difference between the electrodes can induce a thinning of the plate and thus an increase of its planar area, similar to the scenarios encountered when there is no silicone oil. however, we also find that, depending on the material and geometric parameters, an increasing applied voltage can also lead to a thickening of the plate, and thus a shrinking of its area. in that scenario, hessian instability and wrinkling bifurcation may then occur spontaneously once some critical voltages are reached.
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arxiv:2009.04221
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the divergence found by nesterenko, lambiase and scarpetta in the casimir energy on a semi - circular cylinder is attributed to the existence of edges.
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arxiv:hep-th/0006138
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we consider symmetron model in a generalized background with a hope to make it compatible with dark energy. we observe a " no go " theorem at least in case of a conformal coupling. being convinced of symmetron incapability to be dark energy, we try to retain its role for spontaneous symmetry breaking and assign the role of dark energy either to standard quintessence or $ f ( r ) $ theory which are switched on by symmetron field in the symmetry broken phase. the scenario reduces to standard einstein gravity in the high density region. after the phase transition generated by symmetron field, either the $ f ( r ) $ gravity or the standard quintessence are induced in the low density region. we demonstrate that local gravity constraints and other requirements are satisfied although the model could generate the late - time acceleration of universe.
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arxiv:1211.2289
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while the milky way nuclear star cluster has been studied extensively, how it formed is uncertain. studies have shown it contains a solar and supersolar metallicity population that may have formed in - situ, along with a subsolar metallicity population that may have formed via mergers of globular clusters and dwarf galaxies. stellar abundance measurements are critical to differentiate between formation scenarios. we present new measurements of [ $ m / h $ ] and $ \ alpha $ - element abundances [ $ \ alpha / fe $ ] of two subsolar - metallicity stars in the galactic center. these observations were taken with the adaptive - optics assisted high - resolution ( r = 24, 000 ) spectrograph nirspec in the k - band ( 1. 8 - 2. 6 micron ). these are the first $ \ alpha $ - element abundance measurements of sub - solar metallicity stars in the milky way nuclear star cluster. we measure [ $ m / h $ ] = $ - 0. 59 \ pm 0. 11 $, [ $ \ alpha / fe $ ] = $ 0. 05 \ pm 0. 15 $ and [ $ m / h $ ] = $ - 0. 81 \ pm 0. 12 $, [ $ \ alpha / fe $ ] = $ 0. 15 \ pm 0. 16 $ for the two stars at the galactic center ; the uncertainties are dominated by systematic uncertainties in the spectral templates. the stars have an [ $ \ alpha / fe $ ] in - between the [ $ \ alpha / fe $ ] of globular clusters and dwarf galaxies at similar [ $ m / h $ ] values. their abundances are very different than the bulk of the stars in the nuclear star cluster. these results indicate that the sub - solar metallicity population in the milky way nuclear star cluster likely originated from infalling dwarf galaxies or globular clusters and are unlikely to have formed in - situ.
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arxiv:2112.02649
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the ska will discover tens of thousands of pulsars and provide unprecedented data quality on these, as well as the currently known population, due to its unrivalled sensitivity. here, we outline the state of the art of our understanding of magnetospheric radio emission from pulsars and how we will use the ska to solve the open problems in pulsar magnetospheric physics.
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arxiv:1501.00126
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we present a subset of experimental results on charge fluctuation from the heavy - ion collisions to search for phase transition and location of critical point in the qcd phase diagram. measurements from the heavy - ion experiments at the sps and rhic energies observe that total charge fluctuations increase from central to peripheral collisions. the net - charge fluctuations in terms of dynamical fluctuation measure $ \ nu _ { ( + -, dyn ) } $ are studied as a function of collision energy ( \ sqsn ) and centrality of the collisions. the product of $ \ nu _ { ( + -, dyn ) } $ and $ \ langle n _ { ch } \ rangle $ shows a monotonic decrease with collision energies, which indicates that at lhc energy the fluctuations have their origin in the qgp phase. the fluctuations in terms of higher moments of net - proton, net - electric charge and net - kaon have been measured for various \ sqsn. deviations are observed in both $ s \ sigma $ and $ \ kappa \ sigma ^ 2 $ for net - proton multiplicity distributions from the skellam and hadron resonance gas model for \ sqsn $ < $ 39 gev. higher moment results of the net - electric charge and net - kaon do not observe any significant non - monotonic behavior as a function of collision energy. we also discuss the extraction of the freeze - out parameters using particle ratios and experimentally measured higher moments of net - charge fluctuations. the extracted freeze - out parameters from experimentally measured moments and lattice calculations, are found to be in agreement with the results obtained from the fit of particle ratios to the thermal model calculations.
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arxiv:1609.01920
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we present a new technique to extract information on the unitarity triangle from the study of bs - > k pi pi dalitz plot. using isospin symmetry and the possibility to access the decay amplitudes from dalitz analyses, we propose a new strategy to extract the weak phase gamma from bs to k pi pi.
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arxiv:hep-ph/0602207
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this paper quantitatively analysed orchestral conducting patterns, and detected variations as a result of extraneous body movement during conducting, in the first experiment of its kind. a novel live conducting system featuring data capture, processing, and analysis was developed. reliable data of an expert conductor ' s movements was collected, processed, and used to calculate average trajectories for different conducting techniques with various extraneous body movements ; variations between extraneous body movement techniques and controlled technique were definitively determined in a novel quantitative analysis. a portable and affordable mechatronic system was created to capture and process live baton tip data, and was found to be accurate through calibration against a reliable reference. experimental conducting field data was captured through the mechatronic system, and analysed against previously calculated average trajectories ; the extraneous movement used during the field data capture was successfully identified by the system.
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arxiv:2401.15600
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viewpoint plays out is in the philosophical debate as to whether mathematical results are created ( as in art ) or discovered ( as in science ). the popularity of recreational mathematics is another sign of the pleasure many find in solving mathematical questions. = = cultural impact = = = = = artistic expression = = = notes that sound well together to a western ear are sounds whose fundamental frequencies of vibration are in simple ratios. for example, an octave doubles the frequency and a perfect fifth multiplies it by 3 2 { \ displaystyle { \ frac { 3 } { 2 } } }. humans, as well as some other animals, find symmetric patterns to be more beautiful. mathematically, the symmetries of an object form a group known as the symmetry group. for example, the group underlying mirror symmetry is the cyclic group of two elements, z / 2 z { \ displaystyle \ mathbb { z } / 2 \ mathbb { z } }. a rorschach test is a figure invariant by this symmetry, as are butterfly and animal bodies more generally ( at least on the surface ). waves on the sea surface possess translation symmetry : moving one ' s viewpoint by the distance between wave crests does not change one ' s view of the sea. fractals possess self - similarity. = = = popularization = = = popular mathematics is the act of presenting mathematics without technical terms. presenting mathematics may be hard since the general public suffers from mathematical anxiety and mathematical objects are highly abstract. however, popular mathematics writing can overcome this by using applications or cultural links. despite this, mathematics is rarely the topic of popularization in printed or televised media. = = = awards and prize problems = = = the most prestigious award in mathematics is the fields medal, established in 1936 and awarded every four years ( except around world war ii ) to up to four individuals. it is considered the mathematical equivalent of the nobel prize. other prestigious mathematics awards include : the abel prize, instituted in 2002 and first awarded in 2003 the chern medal for lifetime achievement, introduced in 2009 and first awarded in 2010 the ams leroy p. steele prize, awarded since 1970 the wolf prize in mathematics, also for lifetime achievement, instituted in 1978 a famous list of 23 open problems, called " hilbert ' s problems ", was compiled in 1900 by german mathematician david hilbert. this list has achieved great celebrity among mathematicians, and at least thirteen of the problems ( depending how some are interpreted ) have been solved. a new list of seven important problems, titled the "
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https://en.wikipedia.org/wiki/Mathematics
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this paper extends a new class of positivity - preserving, entropy stable spectral collocation schemes developed for the one - dimensional compressible navier - stokes equations in [ 1, 2 ] to three spatial dimensions. the new high - order schemes are provably l2 stable, design - order accurate for smooth solutions, and guarantee the pointwise positivity of thermodynamic variables for 3 - d compressible viscous flows. similar to the 1 - d counterpart, the proposed schemes for the 3 - d navier - stokes equations are constructed by using a flux - limiting technique that combines a positivity - violating entropy stable method of arbitrary order of accuracy and a novel first - order positivity - preserving entropy stable finite volume - type scheme discretized on the same legendre - gauss - lobatto grid points used for constructing the high - order discrete operators. the positivity preservation and excellent discontinuity - capturing properties are achieved by adding an artificial dissipation in the form of the low - and high - order brenner - navier - stokes diffusion operators. to our knowledge, this is the first family of positivity - preserving, entropy stable schemes of arbitrary order of accuracy for the 3 - d compressible navier - stokes equations.
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arxiv:2111.08815
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we present a systematic construction of the penrose coordinates and plane wave limits of spacetimes for which both the null hamilton - jacobi and geodesic equations separate. the method is illustrated for the kerr - nut - ( a ) ds four - dimensional black holes. the plane wave limits of the near horizon geometry of the extreme kerr black hole are also explored. all near horizon geometries of extreme black holes with a killing horizon admit minkowski spacetime as a plane wave limit.
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arxiv:2007.04702
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this review considers a problem in the development of mobile robot adhesion methods with vertical surfaces and the appropriate locomotion mechanism design. the evolution of adhesion methods for wall - climbing robots ( based on friction, magnetic forces, air pressure, electrostatic adhesion, molecular forces, rheological properties of fluids and their combinations ) and their locomotion principles ( wheeled, tracked, walking, sliding framed and hybrid ) is studied. wall - climbing robots are classified according to the applications, adhesion methods and locomotion mechanisms. the advantages and disadvantages of various adhesion methods and locomotion mechanisms are analyzed in terms of mobility, noiselessness, autonomy and energy efficiency. focus is placed on the physical and technical aspects of the adhesion methods and the possibility of combining adhesion and locomotion methods.
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arxiv:1905.09214
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the exchange interaction between nanostructured components is an effective way to enhance the magnetic properties of materials. this effect is used in exchange - coupled magnetic composites, which properties are governed by synergetic impact of constituent phases. texturing is one of the problems that needs to be solved in order for such composites to be used in industry. in this work, we performed experimental and micromagnetic investigation of the exchange - bias properties in co / co3o4 nanocomposites based on nanorods array. specifically, we investigated how the resulting properties will change depending on the nanorods texture. our experiments proved previous theoretical calculations of exchange - bias nanorods array - based composites that showed that magnetic properties of such materials are dependent on the internal texture. tailoring the texture can lead to either increase of exchange - bias field, or to enhancement of material coercivity.
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arxiv:2207.01881
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we prove optimal regularity and a detailed analysis of the free boundary of the solutions to the thin obstacle problem for nonparametric minimal surfaces with flat obstacles.
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arxiv:1804.02890
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we study the electrostatic responses ( i. e. retardation effects due to the propagation of electromagnetic waves are ignored ) of a linear homogeneous and anisotropic ( lha ) dielectric film to an arbitrary external electrostatic potential, which may be generated by charges located either inside or outside it. a formalism is developed to calculate the polarization charges induced in the film. in our derivation, the idea is exploited that a physical boundary can be looked upon as a region of rapid variation in polarization rather than a simple geometric separation. with this no boundary conditions are needed in solving the relevant electrostatics problem. our approach makes it clear that the responses consist of two contributions, one arising from the very presence of surfaces while the other existing even in an infinite medium. the approach can be applied not just to electrostatic but also many problems and is of great pedagogical value. in light of the results, we discuss graphene plasma waves under the influence of a lha dielectric film such as a few - layer hexagonal boron nitride. it is found that the dispersion of these waves is strongly affected by the anisotropy at wavelengths comparable to the film thickness.
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arxiv:1906.03654
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we propose a novel high - dimensional linear regression estimator : the discrete dantzig selector, which minimizes the number of nonzero regression coefficients subject to a budget on the maximal absolute correlation between the features and residuals. motivated by the significant advances in integer optimization over the past 10 - 15 years, we present a mixed integer linear optimization ( milo ) approach to obtain certifiably optimal global solutions to this nonconvex optimization problem. the current state of algorithmics in integer optimization makes our proposal substantially more computationally attractive than the least squares subset selection framework based on integer quadratic optimization, recently proposed in [ 8 ] and the continuous nonconvex quadratic optimization framework of [ 33 ]. we propose new discrete first - order methods, which when paired with state - of - the - art milo solvers, lead to good solutions for the discrete dantzig selector problem for a given computational budget. we illustrate that our integrated approach provides globally optimal solutions in significantly shorter computation times, when compared to off - the - shelf milo solvers. we demonstrate both theoretically and empirically that in a wide range of regimes the statistical properties of the discrete dantzig selector are superior to those of popular $ \ ell _ { 1 } $ - based approaches. we illustrate that our approach can handle problem instances with p = 10, 000 features with certifiable optimality making it a highly scalable combinatorial variable selection approach in sparse linear modeling.
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arxiv:1508.01922
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given a tuple of holomorphic differentials on a riemann surface, one can define a higgs bundle in the hitchin section and a natural symmetric pairing of the higgs bundle. we study whether a higgs bundle of rank 3 in the hitchin section has a compatible harmonic metric when the spectral curve is a 2 - sheeted branched covering of the riemann surface. in particular, we give a condition for higgs bundles in the hitchin section on $ \ mathbb { c } $ or $ \ mathbb { c } ^ * $ to have compatible harmonic metrics.
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arxiv:2403.07258
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in this note we develop an extension of the mar \ v { c } enko - pastur theorem to time series model with temporal correlations. the limiting spectral distribution ( lsd ) of the sample covariance matrix is characterised by an explicit equation for its stieltjes transform depending on the spectral density of the time series. a numerical algorithm is then given to compute the density functions of these lsd ' s.
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arxiv:1109.1612
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we present a multi - wavelength analysis of the young star cluster berkeley 59 ( be 59 ) based on the $ gaia $ data and deep infrared ( ir ) observations with the 3. 58 - m telescopio nazionale galileo and $ spitzer $ space telescope. the mean proper motion of the cluster is found to be $ \ mu $ $ _ \ alpha $ cos $ \ delta $ $ \ sim $ - 0. 63 mas yr $ ^ { - 1 } $ and $ \ mu $ $ _ \ delta $ $ \ sim $ - 1. 83 mas yr $ ^ { - 1 } $ and the kinematic distance of the cluster, $ \ sim $ 1 kpc, is in agreement with previous photometric studies. present data is the deepest available near - ir observations for the cluster so far and reached below 0. 03 m $ _ \ odot $. the mass function of the cluster region is calculated using the statistically cleaned color - magnitude diagram and is similar to the salpeter value for the member stars above 0. 4 m $ _ \ odot $. in contrast, the slope becomes shallower ( $ \ gamma $ $ \ sim $ 0. 01 $ \ pm $ 0. 18 ) in the mass range 0. 04 - 0. 4 m $ _ \ odot $, comparable to other nearby clusters. the spatial distribution of young brown dwarfs ( bds ) and stellar candidates shows a non - homogeneous distribution. this suggests that the radiation feedback from massive stars may be a prominent factor contributing to the bd population in the cluster be 59. we also estimated the star - to - bd ratio for the cluster, which is found to be $ \ sim $ 3. 6. the kolomogorov - smirnov test shows that stellar and bd populations significantly differ, and stellar candidates are near the cluster center compared to the bds, suggesting mass segregation in the cluster toward the substellar mass regime.
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arxiv:2406.08261
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we present the calibration and background model for the large area x - ray proportional counter ( laxpc ) detectors on - board astrosat. laxpc instrument has three nominally identical detectors to achieve large collecting area. these detectors are independent of each other and in the event analysis mode, they record the arrival time and energy of each photon that is detected. the detectors have a time - resolution of 10 $ \ mu $ s and a dead - time of about 42 $ \ mu $ s. this makes laxpc ideal for timing studies. the energy resolution and peak channel to energy mapping were obtained from calibration on ground using radioactive sources coupled with geant4 simulations of the detectors. the response matrix was further refined from observations of the crab x - ray source after launch. at around 20 kev the energy resolution of detector is about 10 - - 15 \ %, while the combined effective area of the 3 detectors is about 6000 cm $ ^ 2 $.
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arxiv:1702.08624
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boron ( b ) containing iii - nitride materials, such as wurtzite ( b, ga ) n alloys, have recently attracted significant interest to tailor the electronic and optical properties of optoelectronic devices operating in the visible and ultraviolet spectral range. however, the growth of high quality samples is challenging and b atom clustering is often observed in ( b, ga ) n alloys. to date, fundamental understanding of the impact of such clustering on electronic and optical properties of these alloys is sparse. in this work we employ density functional theory ( dft ) in the framework of the meta generalized gradient approximation ( modified becke johnson ( mbj ) functional ) to provide insight into this question. we use mbj dft calculations, benchmarked against state - of - the - art hybrid functional dft, on ( b, ga ) n alloys in the experimentally relevant b content range of up to 7. 4 %. our results reveal that b atom clustering can lead to a strong reduction in the bandgap of such an alloy, in contrast to alloy configurations where b atoms are not forming clusters, thus not sharing nitrogen ( n ) atoms. we find that the reduction in bandgap is linked mainly to carrier localization effects in the valence band, which stem from local strain and polarization field effects. however, our study also reveals that the alloy microstructure of a b atom cluster plays an important role : b atom chains along the wurtzite c - axis impact the electronic structure far less strongly when compared to a chain formed within the c - plane. this effect is again linked to local polarization field effects and the orbital character of the involved valence states in wurtzite bn and gan. overall, our calculations show that controlling the alloy microstructure of ( b, ga ) n alloys is of central importance when it comes to utilizing these systems in future optoelectronic devices with improved efficiencies.
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arxiv:2308.07759
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in this paper, we study the possibility of detection of short term terrestrial lower ionospheric response to gamma ray bursts ( grbs ) using a statistical analysis of perturbations of six very low or low frequency ( vlf / lf ) radio signals emitted by transmitters located worldwide and recorded by vlf / lf receiver located in belgrade ( serbia ). we consider a sample of 54 short lasting grbs ( shorter than 1 min ) detected by the swift satellite during the period 2009 - 2012. we find that a statistically significant perturbations can be present in the low ionosphere, and reactions on grbs may be observed immediately after the beginning of the grb event or with a time delay of 60 s - 90 s.
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arxiv:1801.10153
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this work presents an omics - driven modeling pipeline that integrates machine - learning tools to facilitate the dynamic modeling of multiscale biological systems. random forests and permutation feature importance are proposed to mine omics datasets, guiding feature selection and dimensionality reduction for dynamic modeling. continuous and differentiable machine - learning functions can be trained to link the reduced omics feature set to key components of the dynamic model, resulting in a hybrid model. as proof of concept, we apply this framework to a high - dimensional proteomics dataset of $ \ textit { saccharomyces cerevisiae } $. after identifying key intracellular proteins that correlate with cell growth, targeted dynamic experiments are designed, and key model parameters are captured as functions of the selected proteins using gaussian processes. this approach captures the dynamic behavior of yeast strains under varying proteome profiles while estimating the uncertainty in the hybrid model ' s predictions. the outlined modeling framework is adaptable to other scenarios, such as integrating additional layers of omics data for more advanced multiscale biological systems, or employing alternative machine - learning methods to handle larger datasets. overall, this study outlines a strategy for leveraging omics data to inform multiscale dynamic modeling in systems biology and bioprocess engineering.
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arxiv:2410.18864
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we study the problem of supervised linear dimensionality reduction, taking an information - theoretic viewpoint. the linear projection matrix is designed by maximizing the mutual information between the projected signal and the class label ( based on a shannon entropy measure ). by harnessing a recent theoretical result on the gradient of mutual information, the above optimization problem can be solved directly using gradient descent, without requiring simplification of the objective function. theoretical analysis and empirical comparison are made between the proposed method and two closely related methods ( linear discriminant analysis and information discriminant analysis ), and comparisons are also made with a method in which renyi entropy is used to define the mutual information ( in this case the gradient may be computed simply, under a special parameter setting ). relative to these alternative approaches, the proposed method achieves promising results on real datasets.
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arxiv:1206.6397
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of technology. = = = croatia = = = in croatia there are many polytechnic institutes and colleges that offer a polytechnic education. the law about polytechnic education in croatia was passed in 1997. = = = czech republic = = = technical universities brno university of technology ( vut ), founded in 1899, 24, 000 students collegium nobilium in olomouc, 1725 – 1847 czech technical university in prague ( cvut ), college founded in 1707, university since 1806, 23, 000 students, belongs to the oldest technical universities in the world czech university of life sciences prague ( czu ), founded in 1904, focused on agriculture, 18, 000 students institute of chemical technology in prague ( vscht ), founded in 1952, 3, 000 student mendel university in brno ( mendelu ), founded in 1919, focused on agriculture, 9, 000 students technical university of liberec ( tul ), founded in 1953, 8, 000 students technical university of ostrava ( vsb tuo ), founded in 1849, 22, 000 students tomas bata university in zlin ( utb ), founded in 2000, 10, 000 students research institutions academy of sciences of the czech republic ( av cr ), dates back to 1784, 14, 000 research staff altogether technical faculties at universities jan evangelista purkyne university in usti nad labem ( faculty of production technology and management, university founded in 1991 ) university of pardubice ( faculty of chemical technology since 1950, jan perner faculty of transportation since 1991, institute of electrical engineering and informatics since 2002 ) university of west bohemia ( faculty of mechanical engineering, faculty of electrical engineering ; university founded in 1991 ) = = = denmark = = = technical university of denmark, founded in 1829 by hans christian ørsted = = = dominican republic = = = instituto tecnologico de santo domingo universidad tecnologica de santiago = = = ecuador = = = national polytechnic school ( epn ), national polytechnic school, quito, ecuador epn is known for research and education in the applied science, astronomy, atmospheric physics, engineering and physical sciences. the geophysics institute monitors the country ' s seismic, tectonic and volcanic activity in the continental territory and in the galapagos islands. one of the oldest observatories in south america is the quito astronomical observatory. it was founded in 1873 and is located 12 minutes south of the equator in quito, ecuador. the quito astronomical observatory is the national observatory
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https://en.wikipedia.org/wiki/Institute_of_technology
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by the methods of multitype branching processes in random environment counted by random characteristics we study the tail distribution of busy periods and some other characteristics of the branching type polling systems in which the service disciplines, input parameters and service time distributions are changing in a random manner.
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arxiv:0910.0943
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before the thermodynamic limit, macroscopic averages need not commute for a quantum system. as a consequence, aspects of macroscopic fluctuations or of constrained equilibrium require a careful analysis, when dealing with several observables. we propose an implementation of ideas that go back to john von neumann ' s writing about the macroscopic measurement. we apply our scheme to the relation between macroscopic autonomy and an h - theorem, and to the problem of equivalence of ensembles. in particular, we show how the latter is related to the asymptotic equipartition theorem. the main point of departure is an expression of a law of large numbers for a sequence of states that start to concentrate, as the size of the system gets larger, on the macroscopic values for the different macroscopic observables. deviations from that law are governed by the entropy.
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arxiv:math-ph/0601027
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we report the results of a high quality spectral study of early - type galaxies within the coma cluster core. stellar population analysis using lick / ids indices to break the age / metallicity degeneracy are presented, probing their formation history and properties. a clear metallicity trend and a dominant single age population are found.
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arxiv:astro-ph/0111047
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replicated theoretical attempts of relativistic approaches to the pion self - energy in nuclear matter yield unphysical pion spectra. we demonstrate the crucial dependence of the calculated pion spectra on the correct relativistic accounting for the short - range correlation effects on the pion self - energy in the medium. to do this, we simulate the short - range interactions by phenomenological contact terms in the relativistic lagrangian density, and derive the pion self - energy by carefully taking into account the relativistic kinematics. the obtained spectrum for the pion - like excitations in cold nuclear matter shows physically meaningful branches, in contrast to those obtained before by different authors by the use of simplified relativistic approaches to the short - range correlations.
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arxiv:nucl-th/0307025
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rendering objects invisible to impinging acoustic waves ( cloaking ) and creating acoustic illusions ( holography ) has been attempted using active and passive approaches. while passive methods are applicable only to narrow frequency bands, active approaches attempt to respond dynamically, interfering with broadband incident or scattered wavefields by emitting secondary waves. without prior knowledge of the primary wavefield, the signals for the secondary sources need to be estimated and adapted in real - time. this has thus far impeded active cloaking and holography for broadband wavefields. we present experimental results of active acoustic cloaking and holography without prior knowledge of the wavefield so that objects remain invisible and illusions intact even for broadband moving sources. this opens novel research directions and facilitates practical applications including architectural acoustics, and stealth.
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arxiv:2105.07709
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in mathematics, an expression is a written arrangement of symbols following the context - dependent, syntactic conventions of mathematical notation. symbols can denote numbers, variables, operations, and functions. other symbols include punctuation marks and brackets, used for grouping where there is not a well - defined order of operations. expressions are commonly distinguished from formulas : expressions are a kind of mathematical object, whereas formulas are statements about mathematical objects. this is analogous to natural language, where a noun phrase refers to an object, and a whole sentence refers to a fact. for example, 8 x − 5 { \ displaystyle 8x - 5 } is an expression, while the inequality 8 x − 5 ≥ 3 { \ displaystyle 8x - 5 \ geq 3 } is a formula. to evaluate an expression means to find a numerical value equivalent to the expression. expressions can be evaluated or simplified by replacing operations that appear in them with their result. for example, the expression 8 × 2 − 5 { \ displaystyle 8 \ times 2 - 5 } simplifies to 16 − 5 { \ displaystyle 16 - 5 }, and evaluates to 11. { \ displaystyle 11. } an expression is often used to define a function, by taking the variables to be arguments, or inputs, of the function, and assigning the output to be the evaluation of the resulting expression. for example, x ↦ x 2 + 1 { \ displaystyle x \ mapsto x ^ { 2 } + 1 } and f ( x ) = x 2 + 1 { \ displaystyle f ( x ) = x ^ { 2 } + 1 } define the function that associates to each number its square plus one. an expression with no variables would define a constant function. usually, two expressions are considered equal or equivalent if they define the same function. such an equality is called a " semantic equality ", that is, both expressions " mean the same thing. " = = history = = = = = early written mathematics = = = the earliest written mathematics likely began with tally marks, where each mark represented one unit, carved into wood or stone. an example of early counting is the ishango bone, found near the nile and dating back over 20, 000 years ago, which is thought to show a six - month lunar calendar. ancient egypt developed a symbolic system using hieroglyphics, assigning symbols for powers of ten and using addition and subtraction symbols resembling legs in motion. this system, recorded in texts like the rhind mathematical
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https://en.wikipedia.org/wiki/Expression_(mathematics)
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we have embarked in an hst program to determine the masses of black holes in spiral galaxies directly by measuring the line emission arising from an extended accretion disk. for each of the galaxies in our sample we have measured the rotation curve and determined the mass distribution within the inner 5 - 50 pc. we have modeled the stellar mass component using the photometric data from existing hst images and using both data sets we have derived the masses of the black holes in each galaxy. these results will be very important in clarifying the role of the black hole in powering the agn, will shed light into the effectiveness of the accretion mechanisms and finally will be important in addressing the fundamental issue of unification for seyfert 1 and seyfert 2 galaxies.
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arxiv:astro-ph/0405253
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the joint analysis of different cosmological probes, such as galaxy clustering and weak lensing, can potentially yield invaluable insights into the nature of the primordial universe, dark energy and dark matter. however, the development of high - fidelity theoretical models that cover a wide range of scales and redshifts is a necessary stepping - stone. here, we present public high - resolution weak lensing maps on the light cone, generated using the $ n $ - body simulation suite abacussummit in the born approximation, and accompanying weak lensing mock catalogues, tuned via fits to the early data release small - scale clustering measurements of the dark energy spectroscopic instrument ( desi ). available in this release are maps of the cosmic shear, deflection angle and convergence fields at source redshifts ranging from $ z = 0. 15 $ to 2. 45 with $ \ delta z = 0. 05 $ as well as cmb convergence maps ( $ z \ approx 1090 $ ) for each of the 25 $ { \ tt base } $ - resolution simulations ( $ l _ { \ rm box } = 2000 \, h ^ { - 1 } { \ rm mpc } $, $ n _ { \ rm part } = 6912 ^ 3 $ ) as well as for the two $ { \ tt huge } $ simulations ( $ l _ { \ rm box } = 7500 \, h ^ { - 1 } { \ rm mpc } $, $ n _ { \ rm part } = 8640 ^ 3 $ ) at the fiducial abacussummit cosmology ( $ planck $ 2018 ). the pixel resolution of each map is 0. 21 arcmin, corresponding to a healpix $ n _ { \ rm side } $ of 16384. the sky coverage of the $ { \ tt base } $ simulations is an octant until $ z \ approx 0. 8 $ ( decreasing to about 1800 deg $ ^ 2 $ at $ z \ approx 2. 4 $ ), whereas the $ { \ tt huge } $ simulations offer full - sky coverage until $ z \ approx 2. 2 $. mock lensing source catalogues are sampled matching the ensemble properties of the kilo - degree survey, dark energy survey, and hyper - suprime cam weak lensing datasets. the produced mock catalogues are validated against theoretical predictions for various clustering and lensing statistics such as galaxy clustering multipoles
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arxiv:2305.11935
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this paper is devoted to the study of the global existence of smooth solutions for the 3 + 1 dimensional einstein - klein - gordon systems with a $ u ( 1 ) \ times \ mathbb { r } $ isometry group for a class of regular cauchy data. in our first paper \ cite { chen }, we reduce the einstein equations to a 2 + 1 dimensional einstein - wave - klein - gordon system. and we show that the first possible singularity can only occur at the axis. in this paper, we give a proof for the global regularity for the 2 + 1 dimensional system. firstly, we show the non - concentration of the energy near the first possible singularity. then, we prove that the global regularity holds for initial data with small energy.
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arxiv:1905.08968
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we present a correlation between the stellar metallicities and the mutual inclinations of multi - planet systems hosting short - period small planets ( a / rs < 12, rp < 4re ). we analyzed 89 multi - planet systems discovered by kepler, k2, and tess, where the innermost planets have periods shorter than 10 days. we found that the mutual inclinations of the innermost two planets are higher and more diverse around metal - rich stars. the mutual inclinations are calculated as the absolute differences between the best - fit inclinations of the innermost two planets from transit modeling, which represent the lower limits of the true mutual inclinations. the mean and variance of the mutual inclination distribution of the metal - rich systems are 3. 1 + - 0. 5 and 3. 1 + - 0. 4 degrees, while for the metal - poor systems they are 1. 3 + - 0. 2 and 1. 0 + - 0. 2 degrees. this finding suggests that inner planetary systems around metal - rich stars are dynamically hotter. we summarized the theories that could plausibly explain this correlation, including the influence of giant planets, higher solid densities in protoplanetary disks around metal - rich stars, or secular chaos coupled with an excess of angular momentum deficits. planet formation and population synthesis models tracking the mutual inclination evolution would be essential to fully understand this correlation.
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arxiv:2502.00442
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our motivating goal is factorization in krull domains $ h $ with finitely generated class group $ g $. the elasticity $ \ rho ( h ) $ is the maximal number of atoms in any re - factorization of a product of $ k $ atoms. the elasticities are the same as those of a combinatorial monoid of zero - sum sequences $ b ( g _ 0 ) $, where $ g _ 0 \ subseteq g $ are the classes with height one primes. we characterize when finite elasticity holds for any krull domain with finitely generated class group. our results are valid for the more general class of transfer krull monoids ( over a subset $ g _ 0 $ of a finitely generated abelian group $ g $ ). we show there is a minimal $ s \ leq ( d + 1 ) m $, where $ d $ is the torsion free rank and $ m $ is the torsion exponent, such that $ \ rho _ s ( h ) < \ infty $ implies $ \ rho _ k ( h ) < \ infty $ for all $ k \ geq 1 $. this ensures $ \ rho ( h ) < \ infty $ if and only if $ \ rho _ { ( d + 1 ) m } ( h ) < \ infty $. our characterization is in terms of a simple combinatorial obstruction to infinite elasticity : there existing a subset $ g _ 0 ^ \ diamond \ subseteq g _ 0 $ and bound $ n $ such that there are no nontrivial zero - sum sequences with terms from $ g _ 0 ^ \ diamond $, and every minimal zero - sum sequence has at most $ n $ terms from $ g _ 0 \ setminus g _ 0 ^ \ diamond $. we give an explicit description of $ g _ 0 ^ \ diamond $ in terms of the convex geometry of $ g _ 0 $ modulo the torsion subgroup $ g _ t \ leq g $, and show finite elasticity is equivalent to there being no positive linear combination of the elements of this explicitly defined subset equal to $ 0 $ modulo $ g _ t $. we use our results to show finite elasticity implies the set of distances $ \ delta ( h ) $, the catenary degree $ \ mathsf c ( h ) $ ( for krull monoids ) and a weakened tame degree
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arxiv:2012.12757
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this project is an exploration into analysing wifi probe requests, a management frame described as part of the ieee 802. 11 protocol which publicly broadcasts the senders mac address. the intention was to collect these probe requests to use as a basis to link people ' s information to the mac of their device. this would enable people to be identified in future by the presence of their device near a probe request detector. due to data protection and privacy issues preventing access to real data of people ' s names and locations, this project was divided into two parts. firstly, an identification algorithm was developed and tested on simulated data sets of mac addresses and names, to prove mac address identification is possible. and secondly, a distributed system of probe request detectors coupled with a centralised mac address database was developed to demonstrate that these simulated mac addresses are obtainable in the real world. the capturing software was initially developed for unix systems and uses a django - powered web server to store data from multiple capturing devices. python was used to model and test the identification algorithm.
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arxiv:1805.07613
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we explore possible pathways for the creation of ultracold polar nak molecules in their absolute electronic and rovibrational ground state starting from ultracold feshbach molecules. in particular, we present a multi - channel analysis of the electronic ground and k ( 4p ) + na ( 3s ) excited state manifold of nak, analyze the spin character of both the feshbach molecular state and the electronically excited intermediate states and discuss possible coherent two - photon transfer paths from feshbach molecules to rovibronic ground state molecules. the theoretical study is complemented by the demonstration of stirap transfer from the x ^ 1 \ sigma ^ + ( v = 0 ) state to the a ^ 3 \ sigma ^ + manifold on a molecular beam experiment.
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arxiv:1305.3419
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we compare the various chirality measures most widely used in the literature to quantify chiral symmetry in extended solids, i. e., the continuous chirality measure, the hausdorff distance, and the angular momentum. by studying these functions in an algebraically tractable case, we can evaluate their strengths and weaknesses when applied to more complex crystals. going beyond those classical calculations, we propose a new method to quantify the handedness of a crystal based on a pseudoscalar function, i. e., the helicity. this quantity, borrowed from hydrodynamics, can be computed from the eigenvector carrying the system from the high - symmetry non - chiral phase to the low - symmetry chiral phase. different model systems like k $ _ 3 $ nio $ _ 2 $, cscucl $ _ 3 $ and mgti $ _ 2 $ o $ _ 4 $ are used as test cases where we show the superior interest of using helicity to quantify chirality together with the handedness distinction.
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arxiv:2405.16268
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given a lattice $ \ mathbb { l } $ and a class $ k $ of algebraic structures, we say that $ \ mathbb { l } $ \ emph { forces nilpotency } in $ k $ if every algebra $ \ mathbf { a } \ in k $ whose congruence lattice $ \ mathrm { con } ( \ mathbf { a } ) $ is isomorphic to $ \ mathbb { l } $ is nilpotent. we describe congruence lattices that force nilpotency, supernilpotency or solvability for some classes of algebras. for this purpose, we investigate which commutator operations can exist on a given congruence lattice.
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arxiv:1610.01800
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detection of supernova relic neutrinos could provide key support for our current understanding of stellar and cosmological evolution, and precise measurements of these neutrinos could yield novel insights into the universe. in this paper, we studied the detection potential of supernova relic neutrinos using linear alkyl benzene ( lab ) as a slow liquid scintillator. the linear alkyl benzene features good separation of cherenkov and scintillation lights, thereby providing a new route for particle identification. we further addressed key issues in current experiments, including ( 1 ) the charged current background of atmospheric neutrinos in water cherenkov detectors and ( 2 ) the neutral current background of atmospheric neutrinos in typical liquid scintillator detectors. a kiloton - scale lab detector at jinping with $ \ mathcal { o } $ ( 10 ) years of data could discover supernova relic neutrinos with a sensitivity comparable to that of large - volume water cherenkov detectors, typical liquid scintillator detectors, and liquid argon detectors.
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arxiv:1607.01671
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we give a short review of the algebraic procedure known as deformation quantisation, which replaces a commutative algebra with a non - commutative algebra. we use this framework to examine how the objects known as wavefunctions, as known in the quantum curve literature, arise from deformation quantisation. we give an example in terms of the planar conic $ - y + x ^ 2 + 2 xy + y ^ 2 $, and construct an associated wavefunction. we also give an example of the symplectic reduction of a wavefunction, following a procedure from kontsevich and soibelman arxiv : 1701. 09137.
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arxiv:2206.04848
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when performing 3d inpainting using novel - view rendering methods like neural radiance field ( nerf ) or 3d gaussian splatting ( 3dgs ), how to achieve texture and geometry consistency across camera views has been a challenge. in this paper, we propose a framework of 3d gaussian inpainting with depth - guided cross - view consistency ( 3dgic ) for cross - view consistent 3d inpainting. guided by the rendered depth information from each training view, our 3dgic exploits background pixels visible across different views for updating the inpainting mask, allowing us to refine the 3dgs for inpainting purposes. through extensive experiments on benchmark datasets, we confirm that our 3dgic outperforms current state - of - the - art 3d inpainting methods quantitatively and qualitatively.
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arxiv:2502.11801
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magnetic resonance images ( mri ) acquired with low through - plane resolution compromise time and cost. the poor resolution in one orientation is insufficient to meet the requirement of high resolution for early diagnosis of brain disease and morphometric study. the common single image super - resolution ( sisr ) solutions face two main challenges : ( 1 ) local detailed and global anatomical structural information combination ; and ( 2 ) large - scale restoration when applied for reconstructing thick - slice mri into high - resolution ( hr ) iso - tropic data. to address these problems, we propose a novel two - stage network for brain mri sr named transmrsr based on the convolutional blocks to extract local information and transformer blocks to capture long - range dependencies. transmrsr consists of three modules : the shallow local feature extraction, the deep non - local feature capture, and the hr image reconstruction. we perform a generative task to encapsulate diverse priors into a generative network ( gan ), which is the decoder sub - module of the deep non - local feature capture part, in the first stage. the pre - trained gan is used for the second stage of sr task. we further eliminate the potential latent space shift caused by the two - stage training strategy through the self - distilled truncation trick. the extensive experiments show that our method achieves superior performance to other ssir methods on both public and private datasets. code is released at https : / / github. com / goddesshs / transmrsr. git.
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arxiv:2306.06669
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adversarial examples are perturbed inputs that are designed ( from a deep learning network ' s ( dln ) parameter gradients ) to mislead the dln during test time. intuitively, constraining the dimensionality of inputs or parameters of a network reduces the ' space ' in which adversarial examples exist. guided by this intuition, we demonstrate that discretization greatly improves the robustness of dlns against adversarial attacks. specifically, discretizing the input space ( or allowed pixel levels from 256 values or 8 - bit to 4 values or 2 - bit ) extensively improves the adversarial robustness of dlns for a substantial range of perturbations for minimal loss in test accuracy. furthermore, we find that binary neural networks ( bnns ) and related variants are intrinsically more robust than their full precision counterparts in adversarial scenarios. combining input discretization with bnns furthers the robustness even waiving the need for adversarial training for certain magnitude of perturbation values. we evaluate the effect of discretization on mnist, cifar10, cifar100 and imagenet datasets. across all datasets, we observe maximal adversarial resistance with 2 - bit input discretization that incurs an adversarial accuracy loss of just ~ 1 - 2 % as compared to clean test accuracy.
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arxiv:1902.03151
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the power flow process mediated by spin current in the bilayer device consisting of ferromagnetic metal ( fm ) and non - magnetic metal ( nm ) layers is examined by realizing experimental evaluations for each process from the microwave absorption to electromotive force ( emf ) output. the absorption power by ferromagnetic resonance ( fmr ) of the thin fm layer during the emf output is directly measured in operando using an antenna probe system. the transfer efficiency of the absorption power into the nm layer by spin pumping is estimated from strict linewidth evaluation of emf spectra. the maximum transfer efficiency of the spin pumping power to the external load via the inverse spin hall effect is determined to be 4. 2x10 ^ ( - 8 ) under 160mw microwave irradiation using an analysis model assuming a parallel circuit. the main factors reducing the efficiency are found to be low resistivity of the nm layer and the interface loss. these quantifications are important as a first step to consider the efficient transfer of spin energy mediated by spin currents.
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arxiv:2010.08997
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we demonstrate a method for radionuclide assay that is spectroscopic with 100 % counting efficiency for alpha decay. advancing both cryogenic decay energy spectrometry ( des ) and drop - on - demand inkjet metrology, a solution of am - 241 was assayed for massic activity ( bq / g ) with a relative combined standard uncertainty less than 1 %. we implement live - timed counting, spectroscopic analysis, validation by liquid scintillation ( ls ) counting, and confirmation of quantitative solution transfer. experimental des spectra are well modeled with a monte carlo simulation. the model was further used to simulate pu - 238 and pu - 240 impurities, calculate detection limits, and demonstrate the potential for tracer - free multi - nuclide analysis, which will be valuable for new cancer therapeutics based on decay chains, standard reference materials ( srms ) containing impurities, and more widely in nuclear energy, environmental monitoring, security, and forensics.
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arxiv:2411.02565
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as revealed recently by the modeling of the multi - wavelength data of the emission following gw170817 / grb 170817a, there was an off - axis energetic relativistic outflow component launched by this historic double neutron star merger event. in this work we use the results of these modeling to examine the energy extraction process of the central engine. we show that the magnetic process ( i. e., the blandford - znajek mechanism ) is favored, while the neutrino process usually requires a too massive accretion disk if the duration of the central engine activity is comparable to the observed $ t _ { 90 } $ of grb 170817a, unless the timescale of the central engine activity is less than $ \ sim $ 0. 2s. we propose that the grb observations are helpful to constrain the combined tidal parameter $ \ tilde { \ lambda } $, and by adopting the accretion disk mass distribution estimated in bz mechanism, the $ 90 \ % $ credible interval of $ \ tilde { \ lambda } $ for the progenitor of gw170817 is inferred as $ 309 - 954 $.
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arxiv:1811.02558
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in the cascaded approach to spoken language translation ( slt ), the asr output is typically punctuated and segmented into sentences before being passed to mt, since the latter is typically trained on written text. however, erroneous segmentation, due to poor sentence - final punctuation by the asr system, leads to degradation in translation quality, especially in the simultaneous ( online ) setting where the input is continuously updated. to reduce the influence of automatic segmentation, we present a sliding window approach to translate raw asr outputs ( online or offline ) without needing to rely on an automatic segmenter. we train translation models using parallel windows ( instead of parallel sentences ) extracted from the original training data. at test time, we translate at the window level and join the translated windows using a simple approach to generate the final translation. experiments on english - to - german and english - to - czech show that our approach improves 1. 3 - - 2. 0 bleu points over the usual asr - segmenter pipeline, and the fixed - length window considerably reduces flicker compared to a baseline retranslation - based online slt system.
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arxiv:2210.09754
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we study a communication game between a sender and a receiver. the sender chooses one of her signals about the state of the world ( i. e., anecdotes ) and communicates to the receiver who takes an action affecting both players. the sender and the receiver both care about the state of the world but are also influenced by personal preferences, so their ideal actions can differ. we characterize perfect bayesian equilibria. the sender faces a temptation to persuade : she wants to select a biased anecdote to influence the receiver ' s action. anecdotes are still informative to the receiver ( who will debias at equilibrium ) but the attempt to persuade comes at a cost to precision. this gives rise to informational homophily where the receiver prefers to listen to like - minded senders because they provide higher - precision signals. communication becomes polarized when the sender is an expert with access to many signals, with the sender choosing extreme outlier anecdotes at equilibrium ( unless preferences are perfectly aligned ). this polarization dissipates all gains from communication with an increasingly well - informed sender when the anecdote distribution is heavy - tailed. experts can therefore face a curse of informedness : receivers will prefer to listen to less - informed senders who cannot pick biased signals as easily.
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arxiv:2205.13461
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a complete analysis of the consequences of introducing a set of holonomic gauge fixing constraints ( to fix the dynamics ) into a singular lagrangian is performed. it is shown in general that the dynamical system originated from the reduced lagrangian erases all the information regarding the first class constraints of the original theory, but retains its second class. it is proved that even though the reduced lagrangian can be singular, it never possesses any gauge freedom. as an application, the example of $ n \ cdot a = 0 $ gauges in electromagnetism is treated in full detail.
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arxiv:hep-th/9510044
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discussion of ` ` statistical analysis of an archeological find ' ' by andrey feuerverger [ arxiv : 0804. 0079 ]
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arxiv:0804.0090
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we consider off - policy evaluation in the contextual bandit setting for the purpose of obtaining a robust off - policy selection strategy, where the selection strategy is evaluated based on the value of the chosen policy in a set of proposal ( target ) policies. we propose a new method to compute a lower bound on the value of an arbitrary target policy given some logged data in contextual bandits for a desired coverage. the lower bound is built around the so - called self - normalized importance weighting ( sn ) estimator. it combines the use of a semi - empirical efron - stein tail inequality to control the concentration and a new multiplicative ( rather than additive ) control of the bias. the new approach is evaluated on a number of synthetic and real datasets and is found to be superior to its main competitors, both in terms of tightness of the confidence intervals and the quality of the policies chosen.
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arxiv:2006.10460
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we realize and study a model of hybrid inflation in the context of softly broken supersymmetry. the inflaton is taken to be a flat direction in the superfield space and, due to unsuppressed couplings, its soft supersymmetry breaking mass runs with scale. both gauge and yukawa couplings are taken into account and different inflationary scenarios are investigated depending on the relative strenght of the couplings and the mass spectrum.
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arxiv:hep-ph/9812232
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due to the ultra - dense constellation, efficient beam coverage and interference mitigation are crucial to low - earth orbit ( leo ) satellite communication systems, while the conventional directional antennas and fixed - position antenna ( fpa ) arrays both have limited degrees of freedom ( dofs ) in beamforming to adapt to the time - varying coverage requirement of terrestrial users. to address this challenge, we propose in this paper utilizing movable antenna ( ma ) arrays to enhance the satellite beam coverage and interference mitigation. specifically, given the satellite orbit and the coverage requirement within a specific time interval, the antenna position vector ( apv ) and antenna weight vector ( awv ) of the satellite - mounted ma array are jointly optimized over time to minimize the average signal leakage power to the interference area of the satellite, subject to the constraints of the minimum beamforming gain over the coverage area, the continuous movement of mas, and the constant modulus of awv. the corresponding continuous - time decision process for the apv and awv is first transformed into a more tractable discrete - time optimization problem. then, an alternating optimization ( ao ) - based algorithm is developed by iteratively optimizing the apv and awv, where the successive convex approximation ( sca ) technique is utilized to obtain locally optimal solutions during the iterations. moreover, to further reduce the antenna movement overhead, a low - complexity ma scheme is proposed by using an optimized common apv over all time slots. simulation results validate that the proposed ma array - aided beam coverage schemes can significantly decrease the interference leakage of the satellite compared to conventional fpa - based schemes, while the low - complexity ma scheme can achieve a performance comparable to the continuous - movement scheme.
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arxiv:2404.15643
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we introduce the concepts of a pair of valuations and a good generating set and show how they can be used to prove geometric properties of soluble groups.
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arxiv:0907.5579
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in this paper fourier transform and wavelet transform are applied in case of recent 300 years of sunspot numbers to explain the solar cycles. here basically parallel study of fourier and wavelet analysis are done and we have observed that the better result can be obtained from wavelet analysis during sunspot number analysis. we are able to show various minima and maxima in the recent ages of solar cycles with this tool. the exact periodicity and other possible periodicities in the cyclic phenomenon of sunspot activity are determined.
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arxiv:1310.6876
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the rosat x - ray source 1rxs j141256. 0 + 792204 has recently been identified as a likely compact object whose properties suggest it could be a very nearby radio millisecond pulsar at d = 80 - 260pc. we investigated this hypothesis by searching for radio pulsations using the westerbork synthesis radio telescope. we observed 1rxs j141256. 0 + 792204 at 385 and 1380mhz, recording at high time and frequency resolution in order to maintain sensitivity to millisecond pulsations. these data were searched both for dispersed single pulses and using fourier techniques sensitive to constant and orbitally modulated periodicities. no radio pulsations were detected in these observations, resulting in pulsed radio luminosity limits of l _ 400 ~ 0. 3 ( d / 250pc ) ^ 2 mjy kpc ^ 2 and l _ 1400 ~ 0. 03 ( d / 250pc ) ^ 2 mjy kpc ^ 2 at 400 and 1400mhz respectively. the lack of detectable radio pulsations from 1rxs j141256. 0 + 792204 brings into question its identification as a nearby radio pulsar, though, because the pulsar could be beamed away from us, this hypothesis cannot be strictly ruled out.
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arxiv:0710.1788
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we summarize a new realist interpretation of quantum theory that builds on the existing physical structure of the theory and allows experiments to have definite outcomes, but leaves the theory ' s basic dynamical content essentially intact. much as classical systems have specific states that evolve along definite trajectories through configuration spaces, the traditional formulation of quantum theory asserts that closed quantum systems have specific states that evolve unitarily along definite trajectories through hilbert spaces, and our interpretation extends this intuitive picture of states and hilbert - space trajectories to the case of open quantum systems as well. our interpretation - - - which we claim is ultimately compatible with lorentz invariance - - - reformulates wave - function collapse in terms of an underlying interpolating dynamics, makes it possible to derive the born rule from deeper principles, and resolves several open questions regarding ontological stability and dynamics.
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arxiv:1405.6754
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we present a complete analysis of the heavy quark effective theory lagrangian at order $ 1 / m ^ 2 $ in the leading logarithmic approximation, including effects induced by spectator quarks. at this order new correction terms appear in the effective lagrangian, as four - quark operators containing both heavy and light quark fields. we compute the coefficients of these operators to one - loop order and in the leading - logarithmic approximation. two of them break the heavy quark spin symmetry and we estimate their contribution to the hyperfine splitting of the heavy mesons in the factorization approximation. we find that they make a positive contribution to the hyperfine splitting of about 10 % of the measured splitting in the charm case and of up to 5 % in the bottom case.
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arxiv:hep-ph/9607233
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contrastive learning has achieved promising performance in the field of multi - view clustering recently. however, the positive and negative sample construction mechanisms ignoring semantic consistency lead to false negative pairs, limiting the performance of existing algorithms from further improvement. to solve this problem, we propose a multi - view clustering framework named deep contrastive multi - view clustering under semantic feature guidance ( dcmcs ) to alleviate the influence of false negative pairs. specifically, view - specific features are firstly extracted from raw features and fused to obtain fusion view features according to view importance. to mitigate the interference of view - private information, specific view and fusion view semantic features are learned by cluster - level contrastive learning and concatenated to measure the semantic similarity of instances. by minimizing instance - level contrastive loss weighted by semantic similarity, dcmcs adaptively weakens contrastive leaning between false negative pairs. experimental results on several public datasets demonstrate the proposed framework outperforms the state - of - the - art methods.
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arxiv:2403.05768
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water plays a fundamental role in protein stability. however, the effect of the properties of water on the behaviour of proteins is only partially understood. several theories have been proposed to give insight into the mechanisms of cold and pressure denaturation, or the limits of temperature and pressure above which no protein has a stable, functional state, or how unfolding and aggregation are related. here we review our results based on a theoretical approach that can rationalise the water contribution to protein solutions ' free energy. we show, using monte carlo simulations, how we can rationalise experimental data with our recent results. we discuss how our findings can help develop new strategies for the design of novel synthetic biopolymers or possible approaches for mitigating neurodegenerative pathologies.
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arxiv:2103.13093
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in this paper we present the denotational semantics for channel mobility in the unifying theories of programming ( utp ) semantics framework. the basis for the model is the utp theory of reactive processes ( precisely, the utp semantics for communicating sequential processes ( csp ) ), which is slightly extended to allow the mobility of channels : the set of actions in which a process is authorised to participate, originally static or constant ( set during the process ' s definition ), is now made dynamic or variable : it can change during the process ' s execution. a channel is thus moved around by communicating it via other channels and then allowing the receiving process to extend its alphabet with the received channel. new healthiness conditions are stated to ensure an appropriate use of mobile channels.
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arxiv:1606.02018
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we implemented and evaluated a multiple resolution residual network ( mrrn ) for multiple normal organs - at - risk ( oar ) segmentation from computed tomography ( ct ) images for thoracic radiotherapy treatment ( rt ) planning. our approach simultaneously combines feature streams computed at multiple image resolutions and feature levels through residual connections. the feature streams at each level are updated as the images are passed through various feature levels. we trained our approach using 206 thoracic ct scans of lung cancer patients with 35 scans held out for validation to segment the left and right lungs, heart, esophagus, and spinal cord. this approach was tested on 60 ct scans from the open - source aapm thoracic auto - segmentation challenge dataset. performance was measured using the dice similarity coefficient ( dsc ). our approach outperformed the best - performing method in the grand challenge for hard - to - segment structures like the esophagus and achieved comparable results for all other structures. median dsc using our method was 0. 97 ( interquartile range [ iqr ] : 0. 97 - 0. 98 ) for the left and right lungs, 0. 93 ( iqr : 0. 93 - 0. 95 ) for the heart, 0. 78 ( iqr : 0. 76 - 0. 80 ) for the esophagus, and 0. 88 ( iqr : 0. 86 - 0. 89 ) for the spinal cord.
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arxiv:2005.13690
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we prove that for a number of ultrahomogeneous structures $ m $, including those with the free amalgamation property, the powers of the automorphism group $ { \ rm { aut } } ( m ) ^ n $, $ n = 1, 2, \ ldots $, and the group $ l _ 0 ( { \ rm { aut } } ( m ) ) $ of measurable functions with values in $ { \ rm { aut } } ( m ) $, have a cyclically dense conjugacy class, in particular, are topologically 2 - generated. this provides a number of new examples of groups with this property. moreover, we will show that each of these groups is cyclically generated by a pair generating the free group.
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arxiv:1808.08873
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