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we generalize bj \ " { o } rner and stanley ' s poset of compositions to $ m $ - colored compositions. their work draws many analogies between their ( 1 - colored ) composition poset and young ' s lattice of partitions, including links to ( quasi - ) symmetric functions and representation theory. here we show that many of these analogies hold for any number of colors. while many of the proofs for bj \ " { o } rner and stanley ' s poset were simplified by showing isomorphism with the subword order, we remark that with 2 or more colors, our posets are not isomorphic to a subword order. | arxiv:math/0512369 |
the dirichlet problem on a bounded planar domain is more readily understood and solved for the laplace operator than it is for a schrodinger operator. when the potential function is small, we might hope to approximate the solution to the schrodinger equation with the solution to the laplace equation. in this vein we develop a series expansion for the solution and give explicit bounds on the error terms when truncating the series. we also examine a handful of examples and derive similar results for the green function and dirichlet - to - neumann map. | arxiv:1401.1519 |
building real - world complex named entity recognition ( ner ) systems is a challenging task. this is due to the complexity and ambiguity of named entities that appear in various contexts such as short input sentences, emerging entities, and complex entities. besides, real - world queries are mostly malformed, as they can be code - mixed or multilingual, among other scenarios. in this paper, we introduce our submitted system to the multilingual complex named entity recognition ( multiconer ) shared task. we approach the complex ner for multilingual and code - mixed queries, by relying on the contextualized representation provided by the multilingual transformer xlm - roberta. in addition to the crf - based token classification layer, we incorporate a span classification loss to recognize named entities spans. furthermore, we use a self - training mechanism to generate weakly - annotated data from a large unlabeled dataset. our proposed system is ranked 6th and 8th in the multilingual and code - mixed multiconer ' s tracks respectively. | arxiv:2204.13515 |
we work with simple graphs in zf ( zermelo - - fraenkel set theory without the axiom of choice ( ac ) ) and assume that the sets of colors can be either well - orderable or non - well - orderable to prove that the following statements are equivalent to k \ h { o } nig lemma : ( a ) any infinite locally finite connected graph g such that the minimum degree of g is greater than k, has a chromatic number for any fixed integer k greater than or equal to 2. ( b ) any infinite locally finite connected graph has a chromatic index. ( c ) any infinite locally finite connected graph has a distinguishing number. ( d ) any infinite locally finite connected graph has a distinguishing index. our results strengthen some results of stawiski from a recent paper on the role of the axiom of choice in proper and distinguishing colorings since he assumed that the sets of colors can be well - ordered. we also formulate new conditions for the existence of irreducible proper coloring, minimal edge cover, maximal matching, and minimal dominating set in connected bipartite graphs and locally finite connected graphs, which are either equivalent to ac or k \ h { o } nig lemma. moreover, we show that if the axiom of choice for families of 2 element sets holds, then the shelah - - soifer graph has a minimal dominating set. | arxiv:2309.06116 |
in this paper, we study the average of the fourier coefficients of a holomorphic cusp form for the full modular group at primes of the form $ [ g ( n ) ] $. | arxiv:1107.1572 |
we open source an easy to assemble, spoof resistant, high resolution, optical fingerprint reader, called raspireader, using ubiquitous components. by using our open source stl files and software, raspireader can be built in under one hour for only us $ 175. as such, raspireader provides the fingerprint research community a seamless and simple method for quickly prototyping new ideas involving fingerprint reader hardware. in particular, we posit that this open source fingerprint reader will facilitate the exploration of novel fingerprint spoof detection techniques involving both hardware and software. we demonstrate one such spoof detection technique by specially customizing raspireader with two cameras for fingerprint image acquisition. one camera provides high contrast, frustrated total internal reflection ( ftir ) fingerprint images, and the other outputs direct images of the finger in contact with the platen. using both of these image streams, we extract complementary information which, when fused together and used for spoof detection, results in marked performance improvement over previous methods relying only on grayscale ftir images provided by cots optical readers. finally, fingerprint matching experiments between images acquired from the ftir output of raspireader and images acquired from a cots reader verify the interoperability of the raspireader with existing cots optical readers. | arxiv:1712.09392 |
hourglass networks such as the u - net and v - net are popular neural architectures for medical image segmentation and counting problems. typical instances of hourglass networks contain shortcut connections between mirroring layers. these shortcut connections improve the performance and it is hypothesized that this is due to mitigating effects on the vanishing gradient problem and the ability of the model to combine feature maps from earlier and later layers. we propose a method for not only combining feature maps of mirroring layers but also feature maps of layers with different spatial dimensions. for instance, the method enables the integration of the bottleneck feature map with those of the reconstruction layers. the proposed approach is applicable to any hourglass architecture. we evaluated the contextual hourglass networks on image segmentation and object counting problems in the medical domain. we achieve competitive results outperforming popular hourglass networks by up to 17 percentage points. | arxiv:1806.04009 |
we report the preparation of the interface between graphene and the strong rashba - split biag $ _ 2 $ surface alloy and investigatigation of its structure as well as the electronic properties by means of scanning tunneling microscopy / spectroscopy and density functional theory calculations. upon evaluation of the quasiparticle interference patterns the unpertrubated linear dispersion for the $ \ pi $ band of $ n $ - doped graphene is observed. our results also reveal the intact nature of the giant rashba - split surface states of the biag $ _ 2 $ alloy, which demonstrate only a moderate downward energy shift upon the presence of graphene. this effect is explained in the framework of density functional theory by an inward relaxation of the bi atoms at the interface and subsequent delocalisation of the wave function of the surface states. our findings demonstrate a realistic pathway to prepare a graphene protected giant rashba - split biag $ _ 2 $ for possible spintronic applications. | arxiv:1703.07721 |
we show that the classical example $ x $ of a 3 - dimensional generalized manifold constructed by van kampen is another example of not homologically locally connected ( i. e. not hlc ) space. this space $ x $ is not locally homeomorphic to any of the compact metrizable 3 - dimensional manifolds constructed in our earlier paper which are not hlc spaces either. | arxiv:1301.5768 |
the recent rise of interest in virtual reality ( vr ) came with the availability of commodity commercial vr products, such as the head mounted displays ( hmd ) created by oculus and other vendors. one of the main applications of virtual reality that has been recently adopted is streaming sports events. for instance, the last olympics held in rio de janeiro was streamed over the internet for users to view on vr headsets or using 360 video players. a big challenge for streaming vr sports events is the users limited bandwidth and the amount of data required to transmit 360 videos. while 360 video demands high bandwidth, at any time instant users are only viewing a small portion of the video according to the hmd field of view ( fov ). many approaches have been proposed in the literature such as proposing new representations ( e. g. pyramid and offset - cubemap ) and tiling the video and streaming the tiles currently being viewed. in this paper, we propose a tiled streaming framework, where we provide a degrading quality model similar to the state - of - the - art offset - cubemap while minimizing its storage requirements at the server side. we conduct objective studies showing the effectiveness of our approach providing smooth degradation of quality from the user fov to the back of the 360 space. in addition, we conduct subjective studies showing that users tend to prefer our proposed scheme over offset - cubemap in low bandwidth connections, and they don ' t feel difference for higher bandwidth connections. that is, we achieve better perceived quality with huge storage savings up to 670 %. | arxiv:1705.04911 |
recent discussions and research in ai safety have increasingly emphasized the deep connection between ai safety and existential risk from advanced ai systems, suggesting that work on ai safety necessarily entails serious consideration of potential existential threats. however, this framing has three potential drawbacks : it may exclude researchers and practitioners who are committed to ai safety but approach the field from different angles ; it could lead the public to mistakenly view ai safety as focused solely on existential scenarios rather than addressing a wide spectrum of safety challenges ; and it risks creating resistance to safety measures among those who disagree with predictions of existential ai risks. through a systematic literature review of primarily peer - reviewed research, we find a vast array of concrete safety work that addresses immediate and practical concerns with current ai systems. this includes crucial areas like adversarial robustness and interpretability, highlighting how ai safety research naturally extends existing technological and systems safety concerns and practices. our findings suggest the need for an epistemically inclusive and pluralistic conception of ai safety that can accommodate the full range of safety considerations, motivations, and perspectives that currently shape the field. | arxiv:2502.09288 |
error and erasure exponents for the broadcast channel with degraded message sets are analyzed. the focus of our error probability analysis is on the main receiver where, nominally, both messages are to be decoded. a two - step decoding algorithm is proposed and analyzed. this receiver first attempts to decode both messages, failing which, it attempts to decode only the message representing the coarser information, i. e., the cloud center. this algorithm reflects the intuition that we should decode both messages only if we have confidence in the estimates ; otherwise one should only decode the coarser information. the resulting error and erasure exponents, derived using the method of types, are expressed in terms of a penalized form of the modified random coding error exponent. | arxiv:1501.06781 |
by means of first - principles calculations, the structural stability, mechanical properties and electronic structure of the newly synthesized incompressible re2c, re2n, re3n and an analogous compound re3c have been investigated. our results agree well with the available experimental and theoretical data. the proposed re3c is shown to be energetically, mechanically and dynamically stable and also incompressible. furthermore, it is suggested that the incompressibility of these compounds is originated from the strong covalent bonding character with the hybridization of 5d orbital of re and the 2p orbital of c or n, and a zigzag topology of interconnected bonds, e. g., re - re, re - c or re - n bonding. | arxiv:1503.02048 |
theoretical concepts ofn cosmic ray particle acceleration at relativistic plasma flows - - shocks and shear layers - - are reviewed. we begin with a discussion of mildly relativistic shock waves. the role of oblique field configurations and field perturbations in forming the particle energy spectrum and changing the acceleration time scale is considered. then, we report on two interesting attempts to consider particle acceleration at ultra - relativistic shocks. finally, in contrast to the compressive shock discontinuities, we discuss the acceleration processes acting in the boundary layer at the tangential velocity transition. the second - order fermi acceleration as well as the cosmic ray ` viscous ' acceleration provide the mechanisms generating energetic particles there. | arxiv:astro-ph/9808233 |
we prove preservation theorems for $ \ mathcal { l } _ { \ omega _ 1, g } $, the countable fragment of vaught ' s closed game logic. these are direct generalizations of the theorems of \ l { } o \ ' s - tarski ( resp. lyndon ) on sentences of $ \ mathcal { l } _ { \ omega _ 1, \ omega } $ preserved by substructures ( resp. homomorphic images ). the solution, in $ zfc $, only uses general features and can be extended to several variants of other strong first - order logic that do not satisfy the interpolation theorem ; instead, the results on infinitary definability are used. this solves an open problem dating back to 1977. another consequence of our approach is the equivalence of the vop \ v { e } nka principle and a general definability theorem on subsets preserved by homomorphisms. | arxiv:1906.09173 |
for the sparsity - rank - aware least squares estimations, the ligme ( linearly involved generalized moreau enhanced ) model was established recently in [ abe, yamagishi, yamada, 2020 ] to use certain nonconvex enhancements of linearly involved convex regularizers without losing their overall convexities. in this paper, for further advancement of the ligme model by incorporating multiple a priori knowledge as hard convex constraints, we newly propose a convexly constrained ligme ( cligme ) model. the cligme model can utilize multiple convex constraints while preserving benefits achieved by the ligme model. we also present a proximal splitting type algorithm for the proposed cligme model. numerical experiments demonstrate the efficacy of the proposed model and the proposed optimization algorithm in a scenario of signal processing application. | arxiv:2105.02994 |
we present a quantization of previously proposed generalized chern - simons theory with $ gl ( 1, { \ bf r } ) $ algebra in 1 + 1 dimensions. this simplest model shares the common features of generalized cs theories : on - shell reducibility and violations of regularity. on - shell reducibility of the theory requires us to use the lagrangian batalin - vilkovisky and / or hamiltonian batalin - fradkin - vilkovisky formulation. since the regularity condition is violated, their quantization is not straightforward. in the present case we can show that both formulations give an equivalent result. it leads to an interpretation that a physical degree of freedom which does not exist at the classical level appears at the quantum level. | arxiv:hep-th/9605228 |
to achieve reliability in distributed storage systems, data has usually been replicated across different nodes. however the increasing volume of data to be stored has motivated the introduction of erasure codes, a storage efficient alternative to replication, particularly suited for archival in data centers, where old datasets ( rarely accessed ) can be erasure encoded, while replicas are maintained only for the latest data. many recent works consider the design of new storage - centric erasure codes for improved repairability. in contrast, this paper addresses the migration from replication to encoding : traditionally erasure coding is an atomic operation in that a single node with the whole object encodes and uploads all the encoded pieces. although large datasets can be concurrently archived by distributing individual object encodings among different nodes, the network and computing capacity of individual nodes constrain the archival process due to such atomicity. we propose a new pipelined coding strategy that distributes the network and computing load of single - object encodings among different nodes, which also speeds up multiple object archival. we further present rapidraid codes, an explicit family of pipelined erasure codes which provides fast archival without compromising either data reliability or storage overheads. finally, we provide a real implementation of rapidraid codes and benchmark its performance using both a cluster of 50 nodes and a set of amazon ec2 instances. experiments show that rapidraid codes reduce a single object ' s coding time by up to 90 %, while when multiple objects are encoded concurrently, the reduction is up to 20 %. | arxiv:1207.6744 |
two distinct types of magnetoresistance oscillations are observed in two electronic fabry - perot interferometers of different sizes in the integer quantum hall regime. measuring these oscillations as a function of magnetic field and gate voltages, we observe three signatures that distinguish the two types. the oscillations observed in a 2. 0 square micron device are understood to arise from the coulomb blockade mechanism, and those observed in an 18 square micron device from the aharonov - bohm mechanism. this work clarifies, provides ways to distinguish, and demonstrates control over, these distinct physical origins of resistance oscillations seen in electronic fabry - perot interferometers. | arxiv:0901.0127 |
we discuss multichromatic front solutions to the bistable nagumo lattice differential equation. such fronts connect the stable spatially homogeneous equilibria with spatially heterogeneous $ n $ - periodic equilibria and hence are not monotonic like the standard monochromatic fronts. in contrast to the bichromatic case, our results show that these multichromatic fronts can disappear and reappear as the diffusion coefficient is increased. in addition, these multichromatic waves can travel in parameter regimes where the monochromatic fronts are also free to travel. this leads to intricate collision processes where an incoming multichromatic wave can reverse its direction and turn into a monochromatic wave. | arxiv:1901.07227 |
over the last decades, analytical calculations of jet quenching observables have always needed to make a distinction between dense or dilute mediums. although there are different theoretical formalisms suited for each one of these scenarios, taking into account multiple soft and single hard interactions between the probe and the background under a single approach has proven to be a difficult task. in this talk, we will introduce the improved opacity expansion ( ioe ), which extends the well established opacity expansion framework beyond the hard momentum transfer tail, including the regime captured by the bdmps - z / asw approximation. we will focus on the application of the ioe to the computation of the single gluon medium induced spectrum from a hard parton, which constitutes one of the most important theoretical results in jet quenching theory. | arxiv:2111.08049 |
the additive transform of an arithmetic function represents a novel approach to examining the interplay between multiplicative arithmetic function and additive functions. this transform concept introduces a method to systematically generate new arithmetic functions by combining the values of an existing function under an additive operation. the resulting framework not only extends our understanding of classical arithmetic functions but also provides a versatile tool for exploring additive relationships within the realm of number theory. in this article, we present the fundamental principles of the additive transform and illustrate its application through various examples, shedding light on its potential implications for diverse mathematical domains. for all positive integer $ n $. a motivation for the present study is to give a new concept named the additive transform of an arithmetic function $ f $ when $ f $ equals some special arithmetic functions, that new concept can help us to prove many results like : \ begin { equation } \ big ( \ mu * f. id \ big ) ( n ) = \ varphi ( n ) f ( n ) + \ varphi ( n ) \ sum \ limits _ { p ^ { \ alpha } | | n } \ frac { f ( p ^ { \ alpha } ) - f ( p ^ { \ alpha - 1 } ) } { p - 1 } \ end { equation } where $ f $ is an additive function. | arxiv:2312.08929 |
we study the classical version of the 120 - degree model. this is an attractive nearest - neighbor system in three dimensions with xy ( rotor ) spins and interaction such that only a particular projection of the spins gets coupled in each coordinate direction. although the hamiltonian has only discrete symmetries, it turns out that every constant field is a ground state. employing a combination of spin - wave and contour arguments we establish the existence of long - range order at low temperatures. this suggests a mechanism for a type of ordering in certain models of transition - metal compounds where the very existence of long - range order has heretofore been a matter of some controversy. | arxiv:cond-mat/0309691 |
several circumbinary planets have recently been discovered. the orbit of a planet around a binary stellar system poses several dynamic constraints. the effects that radiation from the host stars may have on the planet atmospheres must be considered. because of the configuration of a close binary system, these stars have a high rotation rate, which causes a permanent state of high stellar activity and copious xuv radiation. the accumulated effects are stronger than for exoplanets around single stars, and cause a faster evaporation of their atmospheres. we evaluate the effects that stellar radiation has on the evaporation of exoplanets around binary systems and on the survival of these planets. we considered the xuv spectral range to account for the photons that are easily absorbed by a planet atmosphere that is mainly composed of hydrogen. a more complex atmospheric composition is expected to absorb this radiation more efficiently. we used direct x - ray observations to evaluate the energy in the x - rays range and coronal models to calculate the ( nondetectable ) euv part of the spectrum. the simulations show that exoplanets in a close orbit will suffer strong photoevaporation that may cause a total loss of atmosphere in a short time. a binary system of two solar - like stars will be highly efficient in evaporating the atmosphere of the planet. these systems will be difficult to find, even if they are dynamically stable. still, planets may orbit around binary systems of low mass stars for wider orbits. currently known circumbinary planets are not substantially affected by thermal photoevaporation processes, unless kepler - 47 b has an inflated atmosphere. the distribution of the orbital periods of circumbinary planets is shifted to much longer periods than the average of kepler planets, which supports a scenario of strong photoevaporation in close - in circumbinary planets. | arxiv:1409.0639 |
we describe lie - rinehart algebras in the tensor category $ \ mathcal { lm } $ of linear maps in the sense of loday and pirashvili and construct a functor from lie - rinehart algebras in $ \ mathcal { lm } $ to leibniz algebroids. | arxiv:1412.5981 |
we prove # p - completeness results for counting edge colorings on simple graphs. these strengthen the corresponding results on multigraphs from [ 4 ]. we prove that for any $ \ kappa \ ge r \ ge 3 $ counting $ \ kappa $ - edge colorings on $ r $ - regular simple graphs is # p - complete. furthermore, we show that for planar $ r $ - regular simple graphs where $ r \ in \ { 3, 4, 5 \ } $ counting edge colorings with \ k { appa } colors for any $ \ kappa \ ge r $ is also # p - complete. as there are no planar $ r $ - regular simple graphs for any $ r > 5 $, these statements cover all interesting cases in terms of the parameters $ ( \ kappa, r ) $. | arxiv:2010.04910 |
in this paper, we reexamine prompt engineering for large language models through the lens of automata theory. we argue that language models function as automata and, like all automata, should be programmed in the languages they accept, a unified collection of all natural and formal languages. therefore, traditional software engineering practices - - conditioned on the clear separation of programming languages and natural languages - - must be rethought. we introduce the ann arbor architecture, a conceptual framework for agent - oriented programming of language models, as a higher - level abstraction over raw token generation, and provide a new perspective on in - context learning. based on this framework, we present the design of our agent platform postline, and report on our initial experiments in agent training. | arxiv:2502.09903 |
quantum machine learning techniques have been proposed as a way to potentially enhance performance in machine learning applications. in this paper, we introduce two new quantum methods for neural networks. the first one is a quantum orthogonal neural network, which is based on a quantum pyramidal circuit as the building block for implementing orthogonal matrix multiplication. we provide an efficient way for training such orthogonal neural networks ; novel algorithms are detailed for both classical and quantum hardware, where both are proven to scale asymptotically better than previously known training algorithms. the second method is quantum - assisted neural networks, where a quantum computer is used to perform inner product estimation for inference and training of classical neural networks. we then present extensive experiments applied to medical image classification tasks using current state of the art quantum hardware, where we compare different quantum methods with classical ones, on both real quantum hardware and simulators. our results show that quantum and classical neural networks generates similar level of accuracy, supporting the promise that quantum methods can be useful in solving visual tasks, given the advent of better quantum hardware. | arxiv:2212.07389 |
second language learning can be enabled by tandem collaboration where students are grouped into video conference calls while learning the native language of other student ( s ) on the calls. this places students in an online environment where the more outgoing can actively contribute and engage in dialogue while those more shy and unsure of their second language skills can sit back and coast through the calls. we have built and deployed the l2l system which records timings of conversational utterances from all participants in a call. we generate visualisations including participation rates and timelines for each student in each call and present these on a dashboard. we have recently developed a measure called personal conversational volatility for how dynamic has been each student ' s contribution to the dialogue in each call. we present an analysis of conversational volatility measures for a sample of 19 individual english - speaking students from our university who are learning frenchm, in each of 86 tandem telecollaboration calls over one teaching semester. our analysis shows there is a need to look into the nature of the interactions and see if the choices of discussion topics assigned to them were too difficult for some students and that may have influenced their engagement in some way. | arxiv:2206.13965 |
) and $ [ 320 ^ \ circ, 355 ^ \ circ ] $ ( $ { \ rm re } \, [ \ tau ] < 0 $ ) are consistent with the bau. | arxiv:2105.14292 |
the notion of a $ \ mathcal { k } _ 2 $ - algebra was recently introduced by cassidy and shelton as a generalization of the notion of a koszul algebra. the yoneda algebra of any connected graded algebra admits a canonical $ a _ { \ infty } $ - algebra structure. this structure is trivial if the algebra is koszul. we study the $ a _ { \ infty } $ - structure on the yoneda algebra of a $ \ mathcal { k } _ 2 $ - algebra. for each non - negative integer $ n $ we prove the existence of a $ \ mathcal { k } _ 2 $ - algebra $ b $ and a canonical $ a _ { \ infty } $ - algebra structure on the yoneda algebra of $ b $ such that the higher multiplications $ m _ i $ are nonzero for all $ 3 \ leq i \ leq n + 3 $. we also provide examples which show that the $ \ mathcal { k } _ 2 $ property is not detected by any obvious vanishing patterns among higher multiplications. | arxiv:1005.5185 |
weak boson fusion is expected to be an important higgs production channel at the lhc. complete one - loop results for weak boson fusion in the standard model have been obtained by calculating the full virtual electroweak corrections and photon radiation and implementing these results into the public monte carlo program vbfnlo which includes the nlo qcd corrections. furthermore the dominant supersymmetric one - loop corrections to neutral higgs production, in the general case where the mssm includes complex phases, have been calculated. these results have been combined with all one - loop corrections of standard model type and with the propagator - type corrections from the higgs sector of the mssm up to the two - loop level. within the standard model the electroweak corrections are found to be as important as the qcd corrections after the application of appropriate cuts. the corrections yield a shift in the cross section of order 5 % for a higgs of mass 100 - 200 gev, confirming the result obtained previously in the literature. for the production of a light higgs boson in the mssm the standard model result is recovered in the decoupling limit, while the loop contributions from superpartners to the production of neutral mssm higgs bosons can give rise to corrections in excess of 10 % away from the decoupling region. | arxiv:1012.4789 |
a deep mid - and far - infrared survey in the extended groth strip ( egs ) area gives 3. 6 to 8 \ micron flux densities or upper limits for 253 lyman break galaxies ( lbgs ). the lbgs are a diverse population but with properties correlated with luminosity. the lbgs show a factor of 30 range in indicated stellar mass and a factor of 10 in apparent dust content relative to stellar mass. about 5 % of lbgs are luminous at all wavelengths with powerful emission at rest 6 \ micron. in the rest 0. 9 to 2 \ micron spectral range these galaxies have stellar spectral slopes with no sign of an agn power law component, suggesting that their emission is mainly powered by intensive star formation. galaxies in this luminous population share the infrared properties of cold scuba sources : both are massive and dusty starburst galaxies at $ 2 < z < 3 $ ; their stellar mass is larger than $ 10 ^ { 11 } m _ { \ odot } $. we suggest that these galaxies are the progenitors of present - day giant elliptical galaxies, with a substantial fraction of their stars already formed at $ z \ approx 3 $. | arxiv:astro-ph/0507685 |
toeplitz - structured linear systems arise often in practical engineering problems. correspondingly, a number of algorithms have been developed that exploit toeplitz structure to gain computational efficiency when solving these systems. the earliest " fast " algorithms for toeplitz systems required o ( n ^ 2 ) operations, while more recent " superfast " algorithms reduce the cost to o ( n ( log n ) ^ 2 ) or below. in this work, we present a superfast algorithm for tikhonov regularization of toeplitz systems. using an " extension - and - transformation " technique, our algorithm translates a tikhonov - regularized toeplitz system into a type of specialized polynomial problem known as tangential interpolation. under this formulation, we can compute the solution in only o ( n ( log n ) ^ 2 ) operations. we use numerical simulations to demonstrate our algorithm ' s complexity and verify that it returns stable solutions. | arxiv:1302.6945 |
the electromagnetic vacuum is known to have energy. it has been recently argued that the quantum vacuum can possess momentum, that adds up to the momentum of matter. this ` ` casimir momentum ' ' is closely related to the casimir effect, in which case energy is exchanged. in previous theory it was treated semi - classically. we present a non - relativistic quantum theory for the linear momentum of electromagnetic zero - point fluctuations, considering an harmonic oscillator subject to crossed, quasi - static magnetic and electric and coupled to the quantum vacuum. we derive a contribution of the quantum vacuum to the linear pseudo - momentum and give a new estimate for the achievable speed. our analysis show that the effect exists and that it is finite. | arxiv:0908.4390 |
the spectrum of the laplace - beltrami operator, computed on the spatial slices of causal dynamical triangulations, is a powerful probe of the geometrical properties of the configurations sampled in the various phases of the lattice theory. we study the behavior of the lowest eigenvalues of the spectrum and show that this can provide information about the running of length scales as a function of the bare parameters of the theory, hence about the critical behavior around possible second order transition points in the cdt phase diagram, where a continuum limit could be defined. | arxiv:1903.00430 |
the state - of - the - art for monocular 3d human pose estimation in videos is dominated by the paradigm of 2d - to - 3d pose uplifting. while the uplifting methods themselves are rather efficient, the true computational complexity depends on the per - frame 2d pose estimation. in this paper, we present a transformer - based pose uplifting scheme that can operate on temporally sparse 2d pose sequences but still produce temporally dense 3d pose estimates. we show how masked token modeling can be utilized for temporal upsampling within transformer blocks. this allows to decouple the sampling rate of input 2d poses and the target frame rate of the video and drastically decreases the total computational complexity. additionally, we explore the option of pre - training on large motion capture archives, which has been largely neglected so far. we evaluate our method on two popular benchmark datasets : human3. 6m and mpi - inf - 3dhp. with an mpjpe of 45. 0 mm and 46. 9 mm, respectively, our proposed method can compete with the state - of - the - art while reducing inference time by a factor of 12. this enables real - time throughput with variable consumer hardware in stationary and mobile applications. we release our code and models at https : / / github. com / goldbricklemon / uplift - upsample - 3dhpe | arxiv:2210.06110 |
computational propaganda deploys social or political bots to try to shape, steer and manipulate online public discussions and influence decisions. collective behaviour of populations of social bots has not been yet widely studied, though understanding of collective patterns arising from interactions between bots would aid social bot detection. here we show that there are significant differences in collective behaviour between population of bots and population of humans as detected from their twitter activity. using a large dataset of tweets we have collected during the uk eu referendum campaign, we separated users into population of bots and population of humans based on the length of sequences of their high - frequency tweeting activity. we show that while pairwise correlations between users are weak they co - exist with collective correlated states, however the statistics of correlations and co - spiking probability differ in both populations. our results demonstrate that populations of social bots and human users in social media exhibit collective properties similar to the ones found in social and biological systems placed near a critical point. | arxiv:1706.00077 |
the statement that one can approximate a quantum torus by some twisted convolution c * - algebra of a ( finite ) quotient of z ^ d can be found in the physics literature dealing with quantum field theory and m - theory. in this paper, we show that indeed the quantum tori are limits of such finite dimensional c * - algebras for the quantum gromov - hausdorff distance for compact quantum metric spaces introduced by rieffel, when one chooses the right metric structures. the proof uses a mild extension of a result by ramazan on continuous fields of c * - algebras obtained from groupoid c * - algebras, and extends on rieffel ' s work on the continuity of the quantum tori for the quantum gromov - hausdorff distance. we also show that one can collapse a quantum torus to a lower dimensional quantum torus. | arxiv:math/0310214 |
the recovery of a signal from the magnitudes of its transformation, like the fourier transform, is known as the phase retrieval problem and is of big relevance in various fields of engineering and applied physics. in this paper, we present a fast inertial / momentum based algorithm for the phase retrieval problem and we prove a convergence guarantee for the new algorithm and for the fast griffin - lim algorithm, whose convergence remained unproven in the past decade. in the final chapter, we compare the algorithm for the short time fourier transform phase retrieval with the griffin - lim algorithm and fgla and to other iterative algorithms typically used for this type of problem. | arxiv:2306.12504 |
attention operators have been applied on both 1 - d data like texts and higher - order data such as images and videos. use of attention operators on high - order data requires flattening of the spatial or spatial - temporal dimensions into a vector, which is assumed to follow a multivariate normal distribution. this not only incurs excessive requirements on computational resources, but also fails to preserve structures in data. in this work, we propose to avoid flattening by assuming the data follow matrix - variate normal distributions. based on this new view, we develop kronecker attention operators ( kaos ) that operate on high - order tensor data directly. more importantly, the proposed kaos lead to dramatic reductions in computational resources. experimental results show that our methods reduce the amount of required computational resources by a factor of hundreds, with larger factors for higher - dimensional and higher - order data. results also show that networks with kaos outperform models without attention, while achieving competitive performance as those with original attention operators. | arxiv:2007.08442 |
we continue our study from lynch and mallmann - trenn ( neural networks, 2021 ), of how concepts that have hierarchical structure might be represented in brain - like neural networks, how these representations might be used to recognize the concepts, and how these representations might be learned. in lynch and mallmann - trenn ( neural networks, 2021 ), we considered simple tree - structured concepts and feed - forward layered networks. here we extend the model in two ways : we allow limited overlap between children of different concepts, and we allow networks to include feedback edges. for these more general cases, we describe and analyze algorithms for recognition and algorithms for learning. | arxiv:2304.09540 |
we propose artsagenet, a novel multimodal architecture that integrates graph neural networks ( gnns ) and convolutional neural networks ( cnns ), to jointly learn visual and semantic - based artistic representations. first, we illustrate the significant advantages of multi - task learning for fine art analysis and argue that it is conceptually a much more appropriate setting in the fine art domain than the single - task alternatives. we further demonstrate that several gnn architectures can outperform strong cnn baselines in a range of fine art analysis tasks, such as style classification, artist attribution, creation period estimation, and tag prediction, while training them requires an order of magnitude less computational time and only a small amount of labeled data. finally, through extensive experimentation we show that our proposed artsagenet captures and encodes valuable relational dependencies between the artists and the artworks, surpassing the performance of traditional methods that rely solely on the analysis of visual content. our findings underline a great potential of integrating visual content and semantics for fine art analysis and curation. | arxiv:2105.08190 |
an elementary description of the eightfold way for the non - specialist is presented. this article, for publication in { \ it macmillan encylopedia of physics, supplement : elementary particle physics }, is being submitted to the archive for comments by colleagues. | arxiv:hep-ph/0109241 |
according to the current perception, symptomatic, presymptomatic, and asymptomatic infectious persons can infect the healthy population susceptible to the sars - cov - 2. more importantly, various reports indicate that the number of asymptomatic cases can be several - fold higher than the reported symptomatic cases. in this article, we take the reported cases in india and various states within the country till september 1, as the specimen to understand the progression of the covid - 19. employing a modified seird model, we predict the spread of covid - 19 by the symptomatic as well as asymptomatic infectious population. considering reported infection primarily due to symptomatic we compare the model predicted results with the available data to estimate the dynamics of the asymptomatically infected population. our data indicate that in the absence of the asymptomatic infectious population, the number of symptomatic cases would have been much less. therefore, the current progress of the symptomatic infection can be reduced by quarantining the asymptomatically infectious population via extensive or random testing. this study is motivated strictly towards academic pursuit ; this theoretical investigation is not meant for influencing policy decisions or public health practices. | arxiv:2006.03034 |
the functional integral computation of the various topological invariants, which are associated with the chern - simons field theory, is considered. the standard perturbative setting in quantum field theory is rewieved and new developments in the path - integral approach, based on the deligne - beilinson cohomology, are described in the case of the abelian u ( 1 ) chern - simons field theory formulated in s ^ 1 x s ^ 2. | arxiv:1001.4645 |
static program analysis is used to summarize properties over all dynamic executions. in a unifying approach based on 3 - valued logic properties are either assigned a definite value or unknown. but in summarizing a set of executions, a property is more accurately represented as being biased towards true, or towards false. compilers use program analysis to determine benefit of an optimization. since benefit ( e. g., performance ) is justified based on the common case understanding bias is essential in guiding the compiler. furthermore, successful optimization also relies on understanding the quality of the information, i. e. the plausibility of the bias. if the quality of the static information is too low to form a decision we would like a mechanism that improves dynamically. we consider the problem of building such a reasoning framework and present the fuzzy data - flow analysis. our approach generalize previous work that use 3 - valued logic. we derive fuzzy extensions of data - flow analyses used by the lazy code motion optimization and unveil opportunities previous work would not detect due to limited expressiveness. furthermore we show how the results of our analysis can be used in an adaptive classifier that improve as the application executes. | arxiv:1707.04127 |
we present the results obtained from detailed timing and spectral studies of a black hole candidate maxi ~ j1813 - 095 using { \ it swift }, { \ it nicer }, and { \ it nustar } observations during its 2018 outburst. the timing behaviour of the source is mainly studied by using { \ it nicer } light curves in a $ 0. 5 - 10 $ kev range. we did not find any signature of quasi - periodic oscillations in the power density spectra of the source. we carry out spectral analysis with a combined disk blackbody \ & power - law model, and a physical two - component advective flow ( tcaf ) model. from the combined { \ tt disk blackbody } \ & { \ tt power - law } model, we extracted thermal and non - thermal fluxes, photon index, and inner disk temperature. we also find evidence for weak reflection in the spectra. we have tested the physical tcaf model on a broadband spectrum from { \ it nustar } and { \ it swift } / xrt. the parameters like mass accretion rates, the size of the compton clouds and the shock strength are extracted. our result shows that the source remained in the hard state during the entire outburst which indicates a ` failed ' outburst. we estimate the mass of the black hole as $ 7. 4 \ pm 1. 5 $ $ m _ { \ odot } $ from the spectral study with the tcaf model. we use { \ tt laor } model for the fe k $ \ alpha $ line emission. from this, the spin parameter of the black hole is estimated as $ a ^ * > 0. 76 $. the inclination angle of the system is estimated to be in the range of $ 28 ^ { \ circ } - 45 ^ { \ circ } $ from the reflection model. we estimate the source distance to be $ \ sim 6 $ kpc. | arxiv:2104.12924 |
as capturing devices become common, 3d scans of interior spaces are acquired on a daily basis. through scene comparison over time, information about objects in the scene and their changes is inferred. this information is important for robots and ar and vr devices, in order to operate in an immersive virtual experience. we thus propose an unsupervised object discovery method that identifies added, moved, or removed objects without any prior knowledge of what objects exist in the scene. we model this problem as a combination of a 3d change detection and a 2d segmentation task. our algorithm leverages generic 2d segmentation masks to refine an initial but incomplete set of 3d change detections. the initial changes, acquired through render - and - compare likely correspond to movable objects. the incomplete detections are refined through graph optimization, distilling the information of the 2d segmentation masks in the 3d space. experiments on the 3rscan dataset prove that our method outperforms competitive baselines, with sota results. | arxiv:2312.01148 |
this paper studies supersymmetric ground states of 3d $ \ mathcal { n } = 4 $ supersymmetric gauge theories on a riemann surface of genus $ g $. there are two distinct spaces of supersymmetric ground states arising from the $ a $ and $ b $ type twists on the riemann surface, which lead to effective supersymmetric quantum mechanics with four supercharges and supermultiplets of type $ \ mathcal { n } = ( 2, 2 ) $ and $ \ mathcal { n } = ( 0, 4 ) $ respectively. we compute the space of supersymmetric ground states in each case, graded by flavour and r - symmetries and in different chambers for real mass and fi parameters, for a large class of supersymmetric gauge theories. the results are formulated geometrically in terms of the higgs branch geometry. we perform extensive checks of compatibility with the twisted index and mirror symmetry. | arxiv:2105.08783 |
let $ ( m, g ) $ be a closed, oriented, riemannian manifold of dimension $ m $. we call a systole a shortest non - contractible loop in $ ( m, g ) $ and denote by $ sys ( m, g ) $ its length. let $ sr ( m, g ) = \ frac { { sys ( m, g ) } ^ m } { vol ( m, g ) } $ be the systolic ratio of $ ( m, g ) $. denote by $ sr ( k ) $ the supremum of $ sr ( s, g ) $ among the surfaces of fixed genus $ k \ neq 0 $. in section 2 we construct surfaces with large systolic ratio from surfaces with systolic ratio close to the optimal value $ sr ( k ) $ using cutting and pasting techniques. for all $ k _ i \ geq 1 $, this enables us to prove : $ $ \ frac { 1 } { sr ( k _ 1 + k _ 2 ) } \ leq \ frac { 1 } { sr ( k _ 1 ) } + \ frac { 1 } { sr ( k _ 2 ) }. $ $ we furthermore derive the equivalent intersystolic inequality for $ sr _ h ( k ) $, the supremum of the homological systolic ratio. as a consequence we greatly enlarge the number of genera $ k $ for which the bound $ sr _ h ( k ) \ geq sr ( k ) \ gtrsim \ frac { 4 } { 9 \ pi } \ frac { \ log ( k ) ^ 2 } { k } $ is valid and show that that $ sr _ h ( k ) \ leq \ frac { ( \ log ( 195k ) + 8 ) ^ 2 } { \ pi ( k - 1 ) } $ for all $ k \ geq 76 $. in section 3 we expand on this idea. there we construct product manifolds with large systolic ratio from lower dimensional manifolds. | arxiv:1311.1449 |
let $ \ mathcal { f } $ be a family of graphs, and let $ p, r $ be nonnegative integers. the \ textsc { $ ( p, r, \ mathcal { f } ) $ - covering } problem asks whether for a graph $ g $ and an integer $ k $, there exists a set $ d $ of at most $ k $ vertices in $ g $ such that $ g ^ p \ setminus n _ g ^ r [ d ] $ has no induced subgraph isomorphic to a graph in $ \ mathcal { f } $, where $ g ^ p $ is the $ p $ - th power of $ g $. the \ textsc { $ ( p, r, \ mathcal { f } ) $ - packing } problem asks whether for a graph $ g $ and an integer $ k $, $ g ^ p $ has $ k $ induced subgraphs $ h _ 1, \ ldots, h _ k $ such that each $ h _ i $ is isomorphic to a graph in $ \ mathcal { f } $, and for distinct $ i, j \ in \ { 1, \ ldots, k \ } $, the distance between $ v ( h _ i ) $ and $ v ( h _ j ) $ in $ g $ is larger than $ r $. we show that for every fixed nonnegative integers $ p, r $ and every fixed nonempty finite family $ \ mathcal { f } $ of connected graphs, the \ textsc { $ ( p, r, \ mathcal { f } ) $ - covering } problem with $ p \ leq2r + 1 $ and the \ textsc { $ ( p, r, \ mathcal { f } ) $ - packing } problem with $ p \ leq2 \ lfloor r / 2 \ rfloor + 1 $ admit almost linear kernels on every nowhere dense class of graphs, and admit linear kernels on every class of graphs with bounded expansion, parameterized by the solution size $ k $. we obtain the same kernels for their annotated variants. as corollaries, we prove that \ textsc { distance - $ r $ vertex cover }, \ textsc { distance - $ r $ matching }, \ textsc { $ \ mathcal { f } $ - free vertex deletion }, and \ textsc { induced - $ \ mathcal { f | arxiv:2207.06660 |
we continue the study of distance sensitivity oracles ( dsos ). given a directed graph $ g $ with $ n $ vertices and edge weights in $ \ { 1, 2, \ dots, m \ } $, we want to build a data structure such that given any source vertex $ u $, any target vertex $ v $, and any failure $ f $ ( which is either a vertex or an edge ), it outputs the length of the shortest path from $ u $ to $ v $ not going through $ f $. our main result is a dso with preprocessing time $ o ( n ^ { 2. 5794 } m ) $ and constant query time. previously, the best preprocessing time of dsos for directed graphs is $ o ( n ^ { 2. 7233 } m ) $, and even in the easier case of undirected graphs, the best preprocessing time is $ o ( n ^ { 2. 6865 } m ) $ [ ren, esa 2020 ]. one drawback of our dsos, though, is that it only supports distance queries but not path queries. our main technical ingredient is an algorithm that computes the inverse of a degree - $ d $ polynomial matrix ( i. e. a matrix whose entries are degree - $ d $ univariate polynomials ) modulo $ x ^ r $. the algorithm is adapted from [ zhou, labahn, and storjohann, journal of complexity, 2015 ], and we replace some of its intermediate steps with faster rectangular matrix multiplication algorithms. we also show how to compute unique shortest paths in a directed graph with edge weights in $ \ { 1, 2, \ dots, m \ } $, in $ o ( n ^ { 2. 5286 } m ) $ time. this algorithm is crucial in the preprocessing algorithm of our dso. our solution improves the $ o ( n ^ { 2. 6865 } m ) $ time bound in [ ren, esa 2020 ], and matches the current best time bound for computing all - pairs shortest paths. | arxiv:2102.08569 |
we propose a new algorithm for promise constraint satisfaction problems pcsps ). it is a combination of the $ \ textbf { c } $ onstraint basic $ \ textbf { l } $ p relaxation and the $ \ textbf { a } $ ffine i $ \ textbf { p } $ relaxation ( clap ). we give a characterisation of the power of clap in terms of a minion homomorphism. using this characterisation, we identify a certain weak notion of symmetry which, if satisfied by infinitely many polymorphisms of pcsps, guarantees tractability. we demonstrate that there are pcsps solved by clap that are not solved by any of the existing algorithms for pcsps ; in particular, not by the blp + aip algorithm of brakensiek et al. [ sicomp ' 20 ] and not by a reduction to tractable finite - domain csps. | arxiv:2107.05018 |
the problem of distributed formation control of nonholonomic mobile robots is addressed in this paper, in which the robots are designed to track a formation. collision avoidance among agents is guaranteed using a control law based on a repulsive force. in an uncertain environment where obstacles exist, the construction of repulsive force and rotational direction enables agents to avoid and pass the obstacles. the control inputs of each robot are designed to be bounded. numerical simulations with different formations are implemented to demonstrate the efficacy of the proposed scheme. | arxiv:1704.04566 |
we discuss the relic abundance of massive long lived colored particles with mass of the order of 1 tev. we first examine the case where the massive colored particles have the standard color only. next we consider the " quirk model " suggested by m. luty, in which the colored particles transform under an additional non - abelian gauge group with a scale much smaller than the particles ' mass. in both cases, the relic abundance is reduced via a " late " hadronic annihilation stage. in the second case the relic quirks bind to ordinary quarks forming fractional charged objects and also anomalous heavy isotopes, and the bounds on the relic abundance become extremely severe. the force between quirks, however, has a new confining part that manifests via macroscopic strings and the resulting efficient " very late " annihilations reduce the relic abundance to acceptable levels. the prospects of creating and detecting such particles at lhc and the fate of the particles created are discussed. | arxiv:0712.2681 |
in this study, au + au collisions with the impact parameter of $ 0 \ leq b \ leq 12. 5 $ fm at $ \ sqrt { s _ { nn } } = 200 $ gev are simulated by the ampt model to provide the preliminary final - state information. after transforming these information into appropriate input data ( the energy spectra of final - state charged hadrons ), we construct a deep neural network ( dnn ) and a convolutional neural network ( cnn ) to connect final - state observables with impact parameters. the results show that both the dnn and cnn can reconstruct the impact parameters with a mean absolute error about $ 0. 4 $ fm with cnn behaving slightly better. then, we test the neural networks for different beam energies and pseudorapidity ranges in this task. it turns out that these two models work well for both low and high energies. but when making test for a larger pseudorapidity window, we observe that the cnn shows higher prediction accuracy than the dnn. with the method of grad - cam, we shed light on the ` attention ' mechanism of the cnn model. | arxiv:2112.03824 |
cardiac cine magnetic resonance imaging ( mri ) has been used to characterize cardiovascular diseases ( cvd ), often providing a noninvasive phenotyping tool. ~ while recently flourished deep learning based approaches using cine mri yield accurate characterization results, the performance is often degraded by small training samples. in addition, many deep learning models are deemed a ` ` black box, " for which models remain largely elusive in how models yield a prediction and how reliable they are. to alleviate this, this work proposes a lightweight successive subspace learning ( ssl ) framework for cvd classification, based on an interpretable feedforward design, in conjunction with a cardiac atlas. specifically, our hierarchical ssl model is based on ( i ) neighborhood voxel expansion, ( ii ) unsupervised subspace approximation, ( iii ) supervised regression, and ( iv ) multi - level feature integration. in addition, using two - phase 3d deformation fields, including end - diastolic and end - systolic phases, derived between the atlas and individual subjects as input offers objective means of assessing cvd, even with small training samples. we evaluate our framework on the acdc2017 database, comprising one healthy group and four disease groups. compared with 3d cnn - based approaches, our framework achieves superior classification performance with 140 $ \ times $ fewer parameters, which supports its potential value in clinical use. | arxiv:2301.08959 |
we prepare a triple quantum dot with a separate contact lead to each dot to study pauli spin blockade in the tunnel - coupled three dots in a row. we measure the tunneling current flowing between the center dot and either the left or right dot with the left and right leads as a common source and the center lead as a drain. in the biased stability diagram, we establish pauli spin blockade in the respective neighboring dots, with features similarly obtained in double quantum dot systems. we further realize pauli spin blockade with two different conditions by tuning the inter - dot coupling gates : strong and weak inter - dot tunnel coupling regimes. in the strong - coupling regime we observe significant suppression of co - tunneling through the respective double dots due to pauli spin blockade. we reveal the influence from the third dot in the triple dot device on this co - tunneling pauli spin blockade and clarify that the co - tunneling pauli spin blockade is lifted by the resonant coupling of excited states to the third dot level as well as spin exchange of the left and right dots with the adjacent reservoir. | arxiv:1710.03378 |
in the context of deductive software verification, programs with pointers present a major challenge due to pointer aliasing. in this paper, we introduce pointers to spark, a well - defined subset of the ada language, intended for formal verification of mission - critical software. our solution is based on static alias analysis inspired by rust ' s borrow - checker and affine types, and enforces the concurrent read, exclusive write principle. this analysis has been implemented in the gnat ada compiler and tested against a number of challenging examples including parts of real - life applications. our tests show that only minor changes in the source code are required to fit the idiomatic ada code into spark extended with pointers, which is a significant improvement upon the previous state of the art. the proposed extension has been approved by the language design committee for spark for inclusion in a future version of spark, and is being discussed by the ada rapporteur group for inclusion in the next version of ada. in the report, we give a formal presentation of the analysis rules for a miniature version of spark and prove their soundness. we discuss the implementation and the case studies, and compare our solution with rust. | arxiv:1710.07047 |
we introduce immediate observation petri nets, a class of interest in the study of population protocols ( a model of distributed computation ), and enzymatic chemical networks. in these areas, relevant analysis questions translate into parameterized petri net problems : whether an infinite set of petri nets with the same underlying net, but different initial markings, satisfy a given property. we study the parameterized reachability, coverability, and liveness problems for immediate observation petri nets. we show that all three problems are in pspace for infinite sets of initial markings defined by counting constraints, a class sufficiently rich for the intended application. this is remarkable, since the problems are already pspace - hard when the set of markings is a singleton, i. e., in the non - parameterized case. we use these results to prove that the correctness problem for immediate observation population protocols is pspace - complete, answering a question left open in a previous paper. | arxiv:1902.03025 |
a direct and complete measurement of isotopic fission - fragment yields of $ ^ { 239 } $ u has been performed for the first time. the $ ^ { 239 } $ u fissioning system was produced with an average excitation energy of 8. 3 mev in one - neutron transfer reactions between a $ ^ { 238 } $ u beam and a $ ^ { 9 } $ be target at coulomb barrier energies. the fission fragments were detected and isotopically identified using the vamos + + spectrometer at the ganil facility. this measurement allows to directly evaluate the fission models at excitation energies of fast neutrons, relevant for next - generation nuclear reactors. the present data, in agreement with model calculations, do not support the recently reported anomaly in the fission - fragment yields of $ ^ { 239 } $ u and confirm the persistence of spherical shell effects in the sn region at excitation energies exceeding the fission barrier by few mev. | arxiv:1909.09447 |
( abridged ) context : the assumption of a gas - to - dust mass ratio ( \ gamma ) is a common approach to estimate the basic properties of molecular clouds, such as total mass and column density of molecular hydrogen, from ( sub ) mm continuum observations of the dust. in the milky way a single value is used at all galactocentric radii, independently of the observed metallicity gradients. both models and extragalactic observations suggest that this quantity increases for decreasing metallicity z, typical of the outer regions in disks, where fewer heavy elements are available to form dust grains. aims : we aim to investigate the variation of the gas - to - dust ratio as a function of galactocentric radius and metallicity, to allow a more accurate characterisation of the quantity of molecular gas across the galactic disk, as derived from observations of the dust. methods : observations of the optically thin c \ $ ^ { 18 } \ $ o ( 2 - 1 ) transition were obtained with the apex telescope for a sample of 23 massive and dense star - forming regions in the far outer galaxy ( galactocentric distance greater than 14 kpc ). from the modelling of this line and of the spectral energy distribution of the selected clumps we computed the gas - to - dust ratio and compared it to that of well - studied sources from the atlasgal top100 sample in the inner galactic disk. results : the gradient in gas - to - dust ratio is found to be 0. 087 dex / kpc ( or equivalently \ gamma \ proportional to z \ $ ^ { - 1. 4 } \ $ ). the dust - to - metal ratio, decreases with galactocentric radius, which is the most common situation also for external late - type galaxies. this suggests that grain growth dominates over destruction. the predicted gas - to - dust ratio is in excellent agreement with the estimates in magellanic clouds, for the appropriate value of z. | arxiv:1710.05721 |
until recently, robotics safety research was predominantly about collision avoidance and hazard reduction in the immediate vicinity of a robot. since the advent of large vision and language models ( vlms ), robots are now also capable of higher - level semantic scene understanding and natural language interactions with humans. despite their known vulnerabilities ( e. g. hallucinations or jail - breaking ), vlms are being handed control of robots capable of physical contact with the real world. this can lead to dangerous behaviors, making semantic safety for robots a matter of immediate concern. our contributions in this paper are two fold : first, to address these emerging risks, we release the asimov benchmark, a large - scale and comprehensive collection of datasets for evaluating and improving semantic safety of foundation models serving as robot brains. our data generation recipe is highly scalable : by leveraging text and image generation techniques, we generate undesirable situations from real - world visual scenes and human injury reports from hospitals. secondly, we develop a framework to automatically generate robot constitutions from real - world data to steer a robot ' s behavior using constitutional ai mechanisms. we propose a novel auto - amending process that is able to introduce nuances in written rules of behavior ; this can lead to increased alignment with human preferences on behavior desirability and safety. we explore trade - offs between generality and specificity across a diverse set of constitutions of different lengths, and demonstrate that a robot is able to effectively reject unconstitutional actions. we measure a top alignment rate of 84. 3 % on the asimov benchmark using generated constitutions, outperforming no - constitution baselines and human - written constitutions. data is available at asimov - benchmark. github. io | arxiv:2503.08663 |
we study the effect of the boundary on a system of weakly interacting bosons in one dimension. it strongly influences the boson density which is completely suppressed at the boundary position. away from it, the density is depleted over the distances on the order of the healing length at the mean - field level. quantum fluctuations modify the density profile considerably. the local density approaches the average one as an inverse square of the distance from the boundary. we calculate an analytic expression for the density profile at arbitrary separations from the boundary. we then consider the problem of localization of a foreign quantum particle ( impurity ) in the potential created by the inhomogeneous boson density. at the mean - field level, we find exact results for the energy spectrum of the bound states, the corresponding wave functions, and the condition for interaction - induced localization. the quantum contribution to the boson density gives rise to small corrections of the bound state energy levels. however, it is fundamentally important for the existence of a long - range casimir - like interaction between the impurity and the boundary. | arxiv:2007.10771 |
this text is reproduced with the kind permission of fran \ c { c } ois ap \ ' ery. it was originally edited by fran \ c { c } ois gu \ ' enard and gilbert leli \ ` evre for the book " penser les math \ ' ematiques ". it is the modified and abridged version of a text that appeared previously as s \ ' eminaire de philosophie et math \ ' ematiques de l ' \ ' ecole normale sup \ ' erieure ( s \ ' eance du 26 avril 1976 ), paris, irem paris - nord, 1980, 15 pp., http : / / www. numdam. org / item? id = sphm _ 1976 _ _ _ 1 _ a1 _ 0, as well as in langage et pens \ ' ee math \ ' ematiques : actes du colloque international ( luxembourg, 9 - 11 juin 1976 ), luxembourg, centre universitaire de luxembourg, 1976, pp. 391 - - 410. in its introduction, ap \ ' ery writes : " in default of convincing, this text can set the record straight : we show that the constructive conception does not mutilate, on the contrary, it enriches classical mathematics. " | arxiv:1705.05581 |
within the complete heavy quark effective field theory ( hqeft ), the qcd sum rule approach is used to evaluate the decay constants including 1 / m _ q corrections and the isgur - wise function and other additional important wave functions concerned at 1 / m _ q for the heavy - light mesons. the 1 / m _ q corrections to the scaling law f _ m \ sim f / \ sqrt { m _ m } are found to be small in hqeft, which demonstrates again the validity of 1 / m _ q expansion in hqeft. it is also shown that the residual momentum v. k of heavy quark within hadrons does be around the binding energy \ bar { \ lambda } of the heavy hadrons. the calculations presented in this paper provide a consistent check on the hqeft and shows that the hqeft is more reliable than the usual hqet for describing a slightly off - mass shell heavy quark within hadron as the usual hqet seems to lead to the breakdown of 1 / m _ q expansion in evaluating the meson decay constants. it is emphasized that the introduction of the ` dressed heavy quark ' mass is useful for the heavy - light mesons ( qq ) with m _ q > > \ bar { \ lambda } > > m _ q, while for heavy - heavy bound states ( \ psi _ 1 \ psi _ 2 ) with masses m _ 1, m _ 2 > > \ bar { \ lambda }, like bottom - charm hadrons or similarly for muonium in qed, one needs to treat both particles as heavy effective particles via 1 / m _ 1 and 1 / m _ 2 expansions and redefine the effective bound states and modified ` dressed heavy quark ' masses within the hqeft. | arxiv:hep-ph/0006241 |
also wrote or co - wrote most of the episodes, ran from 1959 to 1964. it featured fantasy, suspense, and horror as well as science fiction, with each episode being a complete story. critics have ranked it as one of the best tv programs of any genre. the animated series the jetsons, while intended as comedy and only running for one season ( 1962 – 1963 ), predicted many inventions now in common use : flat - screen televisions, newspapers on a computer - like screen, computer viruses, video chat, tanning beds, home treadmills, and more. in 1963, the time travel - themed doctor who premiered on bbc television. the original series ran until 1989 and was revived in 2005. it has been extremely popular worldwide and has greatly influenced later tv science fiction. other programs in the 1960s included the outer limits ( 1963 – 1965 ), lost in space ( 1965 – 1968 ), and the prisoner ( 1967 ). star trek ( the original series ), created by gene roddenberry, premiered in 1966 on nbc television and ran for three seasons. it combined elements of space opera and space western. only mildly successful at first, the series gained popularity through syndication and extraordinary fan interest. it became a very popular and influential franchise with many films, television shows, novels, and other works and products. star trek : the next generation ( 1987 – 1994 ) led to six additional live action star trek shows : deep space nine ( 1993 – 1999 ), voyager ( 1995 – 2001 ), enterprise ( 2001 – 2005 ), discovery ( 2017 – 2024 ), picard ( 2020 – 2023 ), and strange new worlds ( 2022 – present ), with more in some form of development. the miniseries v premiered in 1983 on nbc. it depicted an attempted takeover of earth by reptilian aliens. red dwarf, a comic science fiction series aired on bbc two between 1988 and 1999, and on dave since 2009. the x - files, which featured ufos and conspiracy theories, was created by chris carter and broadcast by fox broadcasting company from 1993 to 2002, and again from 2016 to 2018. stargate, a film about ancient astronauts and interstellar teleportation, was released in 1994. stargate sg - 1 premiered in 1997 and ran for 10 seasons ( 1997 – 2007 ). spin - off series included stargate infinity ( 2002 – 2003 ), stargate atlantis ( 2004 – 2009 ), and stargate universe ( 2009 – 2011 ). other 1990s series included quantum leap ( 1989 – 1993 ) | https://en.wikipedia.org/wiki/Science_fiction |
tls is the most widely used cryptographic protocol on the internet. while many recent studies focused on its use in https, none so far analyzed tls usage in e - mail related protocols, which often carry highly sensitive information. since end - to - end encryption mechanisms like pgp are seldomly used, today confidentiality in the e - mail ecosystem is mainly based on the encryption of the transport layer. a well - positioned attacker may be able to intercept plaintext passively and at global scale. in this paper we are the first to present a scalable methodology to assess the state of security mechanisms in the e - mail ecosystem using commodity hardware and open - source software. we draw a comprehensive picture of the current state of every e - mail related tls configuration for the entire ipv4 range. we collected and scanned a massive data - set of 20 million ip / port combinations of all related protocols ( smtp, pop3, imap ) and legacy ports. over a time span of approx. three months we conducted more than 10 billion tls handshakes. additionally, we show that securing server - to - server communication using e. g. smtp is inherently more difficult than securing client - to - server communication. lastly, we analyze the volatility of tls certificates and trust anchors in the e - mail ecosystem and argue that while the overall trend points in the right direction, there are still many steps needed towards secure e - mail. | arxiv:1510.08646 |
of creation science beyond critiques of geology into biology and cosmology as well. soon after its publication, a movement was underway to have the subject taught in united states ' public schools. = = = court determinations = = = the various state laws prohibiting teaching of evolution were overturned in 1968 when the united states supreme court ruled in epperson v. arkansas such laws violated the establishment clause of the first amendment to the united states constitution. this ruling inspired a new creationist movement to promote laws requiring that schools give balanced treatment to creation science when evolution is taught. the 1981 arkansas act 590 was one such law that carefully detailed the principles of creation science that were to receive equal time in public schools alongside evolutionary principles. the act defined creation science as follows : " ' creation - science ' means the scientific evidences for creation and inferences from those evidences. creation - science includes the scientific evidences and related inferences that indicate : sudden creation of the universe, and, in particular, life, from nothing ; the insufficiency of mutation and natural selection in bringing about development of all living kinds from a single organism ; changes only with fixed limits of originally created kinds of plants and animals ; separate ancestry for man and apes ; explanation of the earth ' s geology by catastrophism, including the occurrence of worldwide flood ; and a relatively recent inception of the earth and living kinds. " this legislation was examined in mclean v. arkansas, and the ruling handed down on january 5, 1982, concluded that creation - science as defined in the act " is simply not science ". the judgement defined the following as essential characteristics of science : it is guided by natural law ; it has to be explanatory by reference to nature law ; it is testable against the empirical world ; its conclusions are tentative, i. e., are not necessarily the final word ; and it is falsifiable. the court ruled that creation science failed to meet these essential characteristics and identified specific reasons. after examining the key concepts from creation science, the court found : sudden creation " from nothing " calls upon a supernatural intervention, not natural law, and is neither testable nor falsifiable objections in creation science that mutation and natural selection are insufficient to explain common origins was an incomplete negative generalization ' kinds ' are not scientific classifications, and creation science ' s claims of an outer limit to the evolutionary change possible of species are not explained scientifically or by natural law the separate ancestry of man and apes is an assertion rather than a scientific explanation, and | https://en.wikipedia.org/wiki/Creation_science |
sambursky. pica press. p. 584. isbn 978 - 0 - 87663 - 712 - 8. = = further reading = = = = external links = = ' what is the history of science ', british academy british society for the history of science " scientific change ". internet encyclopedia of philosophy. the cnrs history of science and technology research center in paris ( france ) ( in french ) henry smith williams, history of science, vols 1 – 4, online text digital archives of the national institute of standards and technology ( nist ) digital facsimiles of books from the history of science collection archived 13 january 2020 at the wayback machine, linda hall library digital collections division of history of science and technology of the international union of history and philosophy of science giants of science ( website of the institute of national remembrance ) history of science digital collection : utah state university – contains primary sources by such major figures in the history of scientific inquiry as otto brunfels, charles darwin, erasmus darwin, carolus linnaeus antony van leeuwenhoek, jan swammerdam, james sowerby, andreas vesalius, and others. history of science society ( " hss " ) archived 15 september 2020 at the wayback machine inter - divisional teaching commission ( idtc ) of the international union for the history and philosophy of science ( iuhps ) archived 13 january 2020 at the wayback machine international academy of the history of science international history, philosophy and science teaching group isiscb explore : history of science index an open access discovery tool museo galileo – institute and museum of the history of science in florence, italy national center for atmospheric research ( ncar ) archives the official site of the nobel foundation. features biographies and info on nobel laureates the royal society, trailblazing science from 1650 to date archived 18 august 2015 at the wayback machine the vega science trust free to view videos of scientists including feynman, perutz, rotblat, born and many nobel laureates. a century of science in america : with special reference to the american journal of science, 1818 - 1918 | https://en.wikipedia.org/wiki/History_of_science |
dynamic mode decomposition ( dmd ) is a data - driven method that models high - dimensional time series as a sum of spatiotemporal modes, where the temporal modes are constrained by linear dynamics. for nonlinear dynamical systems exhibiting strongly coherent structures, dmd can be a useful approximation to extract dominant, interpretable modes. in many domains with large spatiotemporal data - - - including fluid dynamics, video processing, and finance - - - the dynamics of interest are often perturbations about fixed points or equilibria, which motivates the application of dmd to centered ( i. e. mean - subtracted ) data. in this work, we show that dmd with centered data is equivalent to incorporating an affine term in the dynamic model and is not equivalent to computing a discrete fourier transform. importantly, dmd with centering can always be used to compute eigenvalue spectra of the dynamics. however, in many cases dmd without centering cannot model the corresponding dynamics, most notably if the dynamics have full effective rank. additionally, we generalize the notion of centering to extracting arbitrary, but known, fixed frequencies from the data. we corroborate these theoretical results numerically on three nonlinear examples : the lorenz system, a surveillance video, and brain recordings. since centering the data is simple and computationally efficient, we recommend it as a preprocessing step before dmd ; furthermore, we suggest that it can be readily used in conjunction with many other popular implementations of the dmd algorithm. | arxiv:1906.05973 |
in this project, we aimed to improve the runtime of minisat, a conflict - driven clause learning ( cdcl ) solver that solves the propositional boolean satisfiability ( sat ) problem. we first used a logistic regression model to predict the satisfiability of propositional boolean formulae after fixing the values of a certain fraction of the variables in each formula. we then applied the logistic model and added a preprocessing period to minisat to determine the preferable initial value ( either true or false ) of each boolean variable using a monte - carlo approach. concretely, for each monte - carlo trial, we fixed the values of a certain ratio of randomly selected variables, and calculated the confidence that the resulting sub - formula is satisfiable with our logistic regression model. the initial value of each variable was set based on the mean confidence scores of the trials that started from the literals of that variable. we were particularly interested in setting the initial values of the backbone variables correctly, which are variables that have the same value in all solutions of a sat formula. our monte - carlo method was able to set 78 % of the backbones correctly. excluding the preprocessing time, compared with the default setting of minisat, the runtime of minisat for satisfiable formulae decreased by 23 %. however, our method did not outperform vanilla minisat in runtime, as the decrease in the conflicts was outweighed by the long runtime of the preprocessing period. | arxiv:1710.11204 |
the concept of resilience embodies the quest towards the ability to sustain shocks, to suffer from these shocks as little as possible, for the shortest time possible, and to recover with the full functionalities that existed before the perturbation. we propose an operation definition of resilience, seeing it as a measure of stress that is complementary to the risk measures. emphasis is put on the distinction between stressors ( the forces acting on the system ) and stress ( the internal reaction of the system to the stressors ). this allows us to elaborate a classification of stress measures and of the possible responses to stressors. we emphasize the need for characterizing the goals of a given system, from which the process of resilience build - up can be defined. distinguishing between exogenous versus endogenous sources of stress allows one to define the corresponding appropriate responses. the main ingredients towards resilience include ( 1 ) the need for continuous multi - variable measurement and diagnosis of endogenous instabilities, ( 2 ) diversification and heterogeneity, ( 3 ) decoupling, ( 4 ) incentives and motivations, and ( 5 ) last but not least the ( obvious ) role of individual strengths. propositions for individual training towards resilience are articulated. the concept of " crisis flight simulators " is introduced to address the intrinsic human cognitive biases underlying the logic of failures and the illusion of control. we also introduce the " time - at - risk " framework, whose goal is to provide continuous predictive updates on possible scenarios and their probabilistic weights, so that a culture of preparedness and adaptation be promoted. these concepts are presented towards building up personal resilience, resilient societies and resilient financial systems. | arxiv:1211.1949 |
hydroxyl ( oh ) is expected to be abundant in diffuse interstellar molecular gas as it forms along with $ h _ 2 $ under similar conditions and within a similar extinction range. we have analyzed absorption measurements of oh at 1665 mhz and 1667 mhz toward 44 extragalactic continuum sources, together with the j = 1 - 0 transitions of $ ^ { 12 } $ co, $ ^ { 13 } $ co, and c $ ^ { 18 } $ o, and the j = 2 - 1 of $ ^ { 12 } $ co. the excitation temperature of oh were found to follow a modified log - normal distribution, $ f ( t { \ rm _ { ex } } ) \ propto \ frac { 1 } { \ sqrt { 2 \ pi } \ sigma } \ rm { exp } \ left [ - \ frac { [ ln ( \ textit { t } _ { ex } ) - ln ( 3. 4 \ k ) ] ^ 2 } { 2 \ sigma ^ 2 } \ right ] $, the peak of which is close to the temperature of the galactic emission background ( cmb + synchron ). in fact, 90 % of the oh has excitation temperature within 2 k of the galactic background at the same location, providing a plausible explanation for the apparent difficulty to map this abundant molecule in emission. the opacities of oh were found to be small and peak around 0. 01. for gas at intermediate extinctions ( a $ \ rm _ v $ $ \ sim $ 0. 05 - 2 mag ), the detection rate of oh with detection limit $ n ( \ mathrm { oh } ) \ simeq 10 ^ { 12 } $ cm $ ^ { - 2 } $ is approximately independent of $ a \ rm _ v $. we conclude that oh is abundant in the diffuse molecular gas and oh absorption is a good tracer of ` dark molecular gas ( dmg ) '. the measured fraction of dmg depends on assumed detection threshold of the co data set. the next generation of highly sensitive low frequency radio telescopes, fast and ska, will make feasible the systematic inventory of diffuse molecular gas, through decomposing in velocity the molecular ( e. g. oh and ch ) absorption profiles toward background continuum sources with numbers exceeding what is currently available by orders of magnitude. | arxiv:1801.04373 |
. wasp - 73 appears to be a significantly evolved star, close to or already in the subgiant phase. wasp - 68 and wasp - 88 are less evolved, although in an advanced stage of core h - burning. | arxiv:1312.1827 |
recurrent neural networks ( rnns ) are powerful architectures to model sequential data, due to their capability to learn short and long - term dependencies between the basic elements of a sequence. nonetheless, popular tasks such as speech or images recognition, involve multi - dimensional input features that are characterized by strong internal dependencies between the dimensions of the input vector. we propose a novel quaternion recurrent neural network ( qrnn ), alongside with a quaternion long - short term memory neural network ( qlstm ), that take into account both the external relations and these internal structural dependencies with the quaternion algebra. similarly to capsules, quaternions allow the qrnn to code internal dependencies by composing and processing multidimensional features as single entities, while the recurrent operation reveals correlations between the elements composing the sequence. we show that both qrnn and qlstm achieve better performances than rnn and lstm in a realistic application of automatic speech recognition. finally, we show that qrnn and qlstm reduce by a maximum factor of 3. 3x the number of free parameters needed, compared to real - valued rnns and lstms to reach better results, leading to a more compact representation of the relevant information. | arxiv:1806.04418 |
estimating the performance of multimedia traffic is important in numerous contexts, including routing and forwarding, qos provisioning, and adaptive video streaming. this paper proposes a network performance estimator which aims at providing, in quasi real - time, network performance estimates for iot multimedia traffic in ieee 802. 11 multihop wireless networks. to our knowledge, the proposed multimedia - aware performance estimator, or mape, is the first deterministic simulation - based estimator that provides real - time per - flow throughput, packet loss and delay estimates while considering inter - flow interference and multi - rate flows, typical of multimedia traffic. our experimental results indicate that mape is able to provide network performance estimates that can be used by iot multimedia services, notably to inform real - time route selection in iot video transmission, at a fraction of the execution time when compared to stochastic network simulators. when compared to existing deterministic simulators, mape yields higher accuracy at comparable execution times due to its ability to consider multi - rate flows. | arxiv:2203.15126 |
examples of simple, separable, unital, purely infinite $ c ^ * $ - - algebras are constructed, including : ( 1 ) some that are not approximately divisible ; ( 2 ) those that arise as crossed products of any of a certain class of $ c ^ * $ - - algebras by any of a certain class of non - - unital endomorphisms ; ( 3 ) those that arise as reduced free products of pairs of $ c ^ * $ - - algebras with respect to any from a certain class of states. | arxiv:funct-an/9601004 |
the properties and stability of hydrous phases are key to unraveling the mysteries of the water cycle in earth ' s interior. under the deep lower mantle conditions, hydrous phases transition into a superionic state. however, the influence of the superionic effect on their stability and dehydration processes remains poorly understood. using ab initio calculations and deep - learning potential molecular dynamics simulations, we discovered a doubly superionic transition in delta - alooh, characterized by the highly diffusive behavior of ionic hydrogen and aluminum within the oxygen sub - lattice. these highly diffusive elements contribute significant external entropy into the system, resulting in exceptional thermostability. free energy calculations indicate that dehydration is energetically and kinetically unfavorable when water exists in a superionic state under core - mantle boundary ( cmb ) conditions. consequently, water can accumulate in the deep lower mantle over earth ' s history. this deep water reservoir plays a crucial role in the global deep water and hydrogen cycles. | arxiv:2503.17906 |
let $ s = k [ x _ 1, \ ldots, x _ n ] $ and let $ i $ be the $ t $ - path ideal of the line graph $ l _ n $ with $ n $ - vertices. it is shown that the set of associated prime ideals of $ i ^ s $ is equal to the set of minimal prime ideals of $ i $ for all $ s \ geq 1 $, and we provide an explicit description of these prime ideals. additionally, as the main contribution of this paper, we derive an explicit formula for the multiplicity of $ s / i ^ s $ for all $ s \ geq 1 $, revealing that it is a polynomial in $ s $ from the beginning. | arxiv:2402.13477 |
echocardiography plays a fundamental role in the extraction of important clinical parameters ( e. g. left ventricular volume and ejection fraction ) required to determine the presence and severity of heart - related conditions. when deploying automated techniques for computing these parameters, uncertainty estimation is crucial for assessing their utility. since clinical parameters are usually derived from segmentation maps, there is no clear path for converting pixel - wise uncertainty values into uncertainty estimates in the downstream clinical metric calculation. in this work, we propose a novel uncertainty estimation method based on contouring rather than segmentation. our method explicitly predicts contour location uncertainty from which contour samples can be drawn. finally, the sampled contours can be used to propagate uncertainty to clinical metrics. our proposed method not only provides accurate uncertainty estimations for the task of contouring but also for the downstream clinical metrics on two cardiac ultrasound datasets. code is available at : https : / / github. com / thierryjudge / contouring - uncertainty. | arxiv:2502.12713 |
multipolar magnetic phases in correlated insulators represent a great challenge for density functional theory ( dft ) due to the coexistence of intermingled interactions, typically spin - orbit coupling, crystal field and complex non - collinear and high - rank inter - site exchange, creating a complected configurational space with multiple minima. though the + u correction to dft allows, in principle, the modelling of such magnetic ground states, its results strongly depend on the initially symmetry breaking, constraining the nature of order parameter in the converged dft + u solution. as a rule, dft + u calculations starting from a set of initial on - site magnetic moments result in a conventional dipolar order. a more sophisticated approach is clearly needed in the case of magnetic multipolar ordering, which is revealed by a null integral of the magnetization density over spheres centered on magnetic atoms, but with non - zero local contributions. here we show how such phases can be efficiently captured using an educated constrained initialisation of the onsite density matrix, which is derived from the multipolar - ordered ground state of an ab initio effective hamiltonian. various properties of such exotic ground states, like their one - electron spectra, become therefore accessible by all - electron dft + u methods. we assess the reliability of this procedure on the ferro - octupolar ground state recently predicted in ba $ _ 2 $ moso $ _ 6 $ ( m = ca, mg, zn ) [ phys. rev. lett. 127, 237201 ( 2021 ) ] | arxiv:2202.12920 |
non - equilibrium diffusive systems are known to exhibit long - range correlations, which decay like the inverse 1 / l of the system size l in one dimension. here, taking the example of the abc model, we show that this size dependence becomes anomalous ( the decay becomes a non - integer power of l ) when the diffusive system approaches a second - order phase transition. this power - law decay as well as the l - dependence of the time - time correlations can be understood in terms of the dynamics of the amplitude of the first fourier mode of the particle densities. this amplitude evolves according to a langevin equation in a quartic potential, which was introduced in a previous work to explain the anomalous behavior of the cumulants of the current near this second - order phase transition. here we also compute some of the cumulants away from the transition and show that they become singular as the transition is approached. | arxiv:1110.1002 |
control and detection of spin order in ferromagnets is the main principle allowing storing and reading of magnetic information in nowadays technology. the large class of antiferromagnets, on the other hand, is less utilized, despite its very appealing features for spintronics applications. for instance, the absence of net magnetization and stray fields eliminates crosstalk between neighbouring devices and the absence of a primary macroscopic magnetization makes spin manipulation in antiferromagnets inherently faster than in ferromagnets. however, control of spins in antiferromagnets requires exceedingly high magnetic fields, and antiferromagnetic order cannot be detected with conventional magnetometry. here we provide an overview and illustrative examples of how electromagnetic radiation can be used for probing and modification of the magnetic order in antiferromagnets. spin pumping from antiferromagnets, propagation of terahertz spin excitations, and tracing the reversal of the antiferromagnetic and ferroelectric order parameter in multiferroics are anticipated to be among the main topics defining the future of this field. | arxiv:1705.10600 |
the future electron - ion collider ( eic ) will operate a series of high - luminosity high - energy electron + proton ( $ e + p $ ) and electron + nucleus ( $ \ textit { e + a } $ ) collisions to study several fundamental questions in the high energy and nuclear physics field. heavy flavor hadron and jet production at the eic plays an important role in exploring both potential modification on the initial - state nuclear parton distribution functions ( npdfs ) and final - state parton propagation and hadronization processes under different nuclear medium conditions. the current design of the eic epic detector has good performance of vertex and track reconstruction, particle identification and energy determination in the pseudorapidity region of $ - 3. 5 < \ eta < 3. 5 $, which will enable a series of high precision heavy flavor hadron and jet measurements. latest simulation studies of the projected nuclear modification factor $ r _ { ea } $ of heavy flavor jets and heavy flavor hadron inside jets in $ e + p $ and $ \ textit { e + au } $ collisions at $ \ sqrt { s } = $ 28. 6 gev and 63. 2 gev as well as the projected statistical accuracy of inclusive and differential charm baryon over meson ratio measurements in $ e + p $ collisions will be presented. the impacts of these proposed eic measurements on constraining the heavy quark propagation properties in cold nuclear medium and exploring the heavy quark hadronization process will be discussed. | arxiv:2501.18044 |
a graph is called chordal if it forbids induced cycles of length 4 or more. in this paper, we attempt to identify the non - nilpotent groups whose power graph is a chordal graph ( this question was raised by cameron in [ 4 ] ). in this direction, we characterise the direct product of finite groups having chordal power graphs. we classify all finite simple groups of lie type whose power graph is chordal. further, we prove that the power graph of a sporadic simple group is always non - chordal. in addition, we show that almost all groups of order up to 47 have chordal power graphs. | arxiv:2208.14879 |
the production of heavy flavour hadrons in $ pp $ collisions at large values of their transverse momenta can be a new unique source for estimation of intrinsic heavy quark contribution to the proton. we analyze the inclusive production of the open strangeness and the semi - inclusive hard processes of the photon and vector boson production accompanied by the $ c $ - or $ b $ - jets in $ pp $ collisions. we show that one should select the parton - level ( sub ) processes ( and final - state signatures ) that are the most sensitive to the intrinsic heavy quark contributions. we present some predictions for these processes made within the perturbative qcd including the intrinsic strangeness and intrinsic charm in the proton that can be verified in the na61 experiment and at lhc. | arxiv:1309.3168 |
in numerous low - mass x - ray binaries khz quasi - periodic oscillations ( khz qpos ) are detected. we observed the atoll sources gx 9 + 1 and gx 9 + 9 with the rxte satellite. both sources were on the ( upper ) banana branch during our observations. no khz qpos were detected, with upper limits of 1. 3 - 1. 8 %. it is known from other atoll sources ( e. g. 4u 1636 - 53 and 4u 1820 - 30 ) that when they are in the upper banana branch the khz qpos are not detected. thus, it remains possible that when gx 9 + 1 and gx 9 + 9 are observed longer on the lower banana, or even in the island state, khz qpos are detected in these sources. | arxiv:astro-ph/9711222 |
let $ \ omega \ subset \ mathbb r ^ { n } \ ( n \ geq2 ) $ be either an open ball $ b _ r $ centred at the origin or the whole space. we study the existence of positive, radial solutions of quasilinear elliptic systems of the form \ begin { equation * } \ left \ { \ begin { aligned } \ delta _ { p } u & = f _ 1 ( | x | ) g _ 1 ( v ) | \ nabla u | ^ { \ alpha } & & \ quad \ mbox { in } \ omega, \ \ \ delta _ { p } v & = f _ 2 ( | x | ) g _ 2 ( v ) h ( | \ nabla u | ) & & \ quad \ mbox { in } \ omega, \ end { aligned } \ right. \ end { equation * } where $ \ alpha \ geq 0 $, $ \ delta _ { p } $ is the $ p $ - laplace operator, $ p > 1 $, and for $ i, j = 1, 2 $ we assume $ f _ i, g _ j, h $ are continuous, non - negative and non - decreasing functions. for functions $ g _ j $ which grow polynomially, we prove sharp conditions for the existence of positive radial solutions which blow up at $ \ partial b _ { r } $, and for the existence of global solutions. | arxiv:2310.11547 |
we present a new method for the constraint - based synthesis of termination arguments for linear loop programs based on linear ranking templates. linear ranking templates are parameterized, well - founded relations such that an assignment to the parameters gives rise to a ranking function. our approach generalizes existing methods and enables us to use templates for many different ranking functions with affine - linear components. we discuss templates for multiphase, nested, piecewise, parallel, and lexicographic ranking functions. these ranking templates can be combined to form more powerful templates. because these ranking templates require both strict and non - strict inequalities, we use motzkin ' s transposition theorem instead of farkas ' lemma to transform the generated $ \ exists \ forall $ - constraint into an $ \ exists $ - constraint. | arxiv:1503.00193 |
we extend the classical avez - seifert theorem to trajectories of charged test particles with fixed charge - to - mass ratio. in particular, given two events x _ { 0 } and x _ { 1 }, with x _ { 1 } in the chronological future of x _ { 0 }, we find an interval i = ] - r, r [ such that for any q / m in i there is a timelike connecting solution of the lorentz force equation. moreover, under the assumption that there is no null geodesic connecting x _ 0 and x _ 1, we prove that to any value of | q / m | there correspond at least two connecting timelike solutions which coincide only if they are geodesics. | arxiv:gr-qc/0211100 |
to face the programming challenges related to heterogeneous computing, intel recently introduced oneapi, a new programming environment that allows code developed in data parallel c + + ( dpc + + ) language to be run on different devices such as cpus, gpus, fpgas, among others. to tackle cuda - based legacy codes, oneapi provides a compatibility tool ( dpct ) that facilitates the migration to dpc + +. due to the large amount of existing cuda - based software in the bioinformatics context, this paper presents our experiences porting sw # db, a well - known sequence alignment tool, to dpc + + using dpct. from the experimental work, it was possible to prove the usefulness of dpct for sw # db code migration and the cross - gpu vendor, cross - architecture portability of the migrated dpc + + code. in addition, the performance results showed that the migrated dpc + + code reports similar efficiency rates to its cuda - native counterpart or even better in some tests ( approximately + 5 % ). | arxiv:2203.11100 |
riemannian geometry has been applied to brain computer interface ( bci ) for brain signals classification yielding promising results. studying electroencephalographic ( eeg ) signals from their associated covariance matrices allows a mitigation of common sources of variability ( electronic, electrical, biological ) by constructing a representation which is invariant to these perturbations. while working in euclidean space with covariance matrices is known to be error - prone, one might take advantage of algorithmic advances in information geometry and matrix manifold to implement methods for symmetric positive - definite ( spd ) matrices. this paper proposes a comprehensive review of the actual tools of information geometry and how they could be applied on covariance matrices of eeg. in practice, covariance matrices should be estimated, thus a thorough study of all estimators is conducted on real eeg dataset. as a main contribution, this paper proposes an online implementation of a classifier in the riemannian space and its subsequent assessment in steady - state visually evoked potential ( ssvep ) experimentations. | arxiv:1501.03227 |
we use 62, 185 quasars from the sloan digital sky survey dr5 sample and standard virial mass scaling laws based on the widths of h beta, mg ii, and c iv lines and adjacent continuum luminosities to explore the maximum mass of quasars as a function of redshift, which we find to be sharp and evolving. this evolution is in the sense that high - mass black holes cease their luminous accretion at higher redshift than lower - mass black holes. further, turnoff for quasars at any given mass is more highly synchronized than would be expected given the dynamics of their host galaxies. we investigate potential signatures of the quasar turnoff mechanism, including a dearth of high - mass quasars at low eddington ratio. these new results allow a closer examination of several common assumptions used in modeling quasar accretion and turnoff. | arxiv:0911.3155 |
axion is a promising candidate for ultralight dark matter which may cause a polarization rotation of laser light. recently, a new idea of probing the axion dark matter by optical linear cavities used in the arms of gravitational wave detectors has been proposed [ phys. rev. lett. 123, 111301 ( 2019 ) ]. in this article, a realistic scheme of the axion dark matter search with the arm cavity transmission ports is revisited. since photons detected by the transmission ports travel in the cavity for odd - number of times, the effect of axion dark matter on their phases is not cancelled out and the sensitivity at low - mass range is significantly improved compared to the search using reflection ports. we also take into account the stochastic nature of the axion field and the availability of the two detection ports in the gravitational wave detectors. the sensitivity to the axion - photon coupling, $ g _ { a \ gamma } $, of the ground - based gravitational wave detector, such as advanced ligo, with 1 - year observation is estimated to be $ g _ { a \ gamma } \ sim 3 \ times10 ^ { - 12 } $ gev $ ^ { - 1 } $ below the axion mass of $ 10 ^ { - 15 } $ ev, which improves upon the limit achieved by the cern axion solar telescope. | arxiv:2106.06800 |
the phenomenon of a partial 2h \ rightarrow1t phase transition within multiwalled ws2 nanotubes under substitutional rhenium doping is discovered by means of high - resolution transmission electron microscopy. using density - functional calculations for the related mos2 compound we consider a possible origin of this phase transition, which was known formerly only for ws2 and mos2 intercalated by alkali metals. an interplay between the stability of layered or nanotubular forms of 2h and 1t allotropes is found to be intimately related with their electronic structures and electro - donating ability of an impurity. | arxiv:1110.3848 |
it is known that, in the chiral limit, spatially inhomogeneous chiral condensate occurs in the nambu - jona - lasinio ( njl ) model at finite density within a mean - field approximation. we study here how an introduction of current quark mass affects the ground state with the spatially inhomogeneous chiral condensate. numerical calculations show that, even if the current quark mass is introduced, the spatially inhomogeneous chiral condensate can take place. in order to obtain the ground state, the thermodynamic potential is calculated with a mean - field approximation. the influence of finite current mass on the thermodynamic potential consists of following two parts. one is a part coming from the field energy of the condensate, which favors inhomogeneous chiral condensate. the other is a part coming from the dirac sea and the fermi sea, which favors homogeneous chiral condensate. we also find that when the spatially inhomogeneous chiral condensate occurs, the baryon number density becomes spatially inhomogeneous. | arxiv:0908.0594 |
loop corrections for physics beyond the standard model are computed. dwe discuss the influence of new physics on cp - violating observables. assuming the standard model gives a correct description of tree level processes, we show how a consistent procedure can determine the parameters of the standard model and check its validity also in loop induced processes. a method to include new physics in a systematic way is sketched. | arxiv:hep-ph/0101259 |
we implement the rayleigh - ritz method in supersymmetric quantum mechanics with flat directions, and extract the s - matrix and metastable resonances. the effectiveness of the method is demonstrated in two strongly coupled systems : an n = 1 toy supermembrane model, and an n = 4 model with a u ( 1 ) gauge multiplet and a charged chiral multiplet. | arxiv:1610.07275 |
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