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changes over time in brain anatomy can provide important insight for treatment design or scientific analyses. we present a method that predicts how a brain mri for an individual will change over time. we model changes using a diffeomorphic deformation field that we predict using function using convolutional neural networks. given a predicted deformation field, a baseline scan can be warped to give a prediction of the brain scan at a future time. we demonstrate the method using the adni cohort, and analyze how performance is affected by model variants and the subject - specific information provided. we show that the model provides good predictions and that external clinical data can improve predictions. | arxiv:2006.00090 |
the einstein - hilbert ( eh ) action is peculiar in many ways. some of the peculiar features have already been highlighted in literature. in the present article, we have discussed some peculiar features of eh action which has not been discussed earlier. it is well - known that there are several ways of decomposing the eh action into the bulk and the surface part with different underlying motivations. we provide a review on all of these decompositions. then, we attempt to study the static coordinate as a limiting case of a time - dependent coordinate via dynamic upgradation of the constant metric parameters. firstly, we study the consequences when the constant parameters, present in a static and spherically symmetric ( sss ) metric, are promoted to the time dependent variables, which allows us to incorporate the time - dependence in the static coordinate. we find that, in every sets of decomposition, the expression of the bulk term remains invariant, whereas the surface term changes by a total derivative term. finally, when we obliterate the time dependence of the metric parameters, we find that the expression of the ricci - scalar ( or the eh action ) does not go back to its original value. instead, we find that the curvature becomes singular on the horizon, which implies a topological change from the original spacetime. | arxiv:2207.08199 |
we present a phenomenological model of feedback in early - type galaxies that tracks the evolution of the interstellar medium gas mass, metallicity, and temperature. modeling the star formation rate as a schmidt law with a temperature - dependent efficiency, we find that intermittent episodes of star formation are common in moderate - size ellipticals. our model is applicable in the case in which the thermalization time from sn is sufficiently long that spatial variations are relatively unimportant, an appropriate assumption for the empirical parameters adopted here. the departure from a standard scenario of passive evolution implies significantly younger luminosity - weighted ages for the stellar populations of low - mass galaxies at moderate redshifts, even though the more physically meaningful mass - weighted ages are changed only slightly. secondary bursts of star formation also lead to a natural explanation of the large scatter in the nuv - optical relation observed in clusters at moderate redshift and account for the population of e + a galaxies that display a spheroidal morphology. as the late - time formation of stars in our model is due to the gradual cooling of the interstellar medium, which is heated to temperatures ~ 1 kev by the initial burst of supernovae, our conclusions do not rely on any environmental effects or external mechanisms. furthermore, a simple estimate of the x - ray emission from this supernova heated gas leads to an l _ x vs l _ b correlation that is in good agreement with observed values. thus feedback processes may be essential to understanding the observed properties of early - type galaxies from the optical to the x - ray. | arxiv:astro-ph/0207535 |
spectator processes which are in thermal equilibrium during the period of baryogenesis influence the final baryon asymmetry. we study this effect quantitatively for thermal leptogenesis where we find a suppression by a factor o ( 1 ). | arxiv:hep-ph/0104189 |
when a medium composed of microscopic elements is subjected to a high intensity field, the individual behaviors of microscopic elements can become chaotic. in such cases it is important to consider the effects of this irregularity at microscopical level onto the macroscopic behavior of the medium. we show that the macroscopic field produced by a large group of chaotic scatterers can remain regular, due to the partial or complete phase coherence of the scattering elements and the incoherence of the chaotic components of their responses. thus when only macroscopic fields are observed, one may be unaware of chaotic microscopical motion, as it appears to be hidden from the observer. the coupling among the elements may lead to partial chaos synchronization, which exposes the chaotic nature of the system making the oscillations of macroscopic fields more irregular. | arxiv:nlin/0106008 |
we prove two theorems which imply that any stationary nonlinear electromagnetic field obeying a dominant energy condition in a strictly stationary, everywhere regular, asymptotically flat spacetime must be either trivial or a stealth field. the first theorem holds in static spacetimes and is independent of the gravitational part of the action, as long as the coupling of the electromagnetic field to the gravitational field is minimal. the second theorem assumes einstein - - hilbert gravitational action and relies on the positive energy theorem, but does not assume that the spacetime metric is static. in addition, we discuss possible generalizations of these results, to theories with charged matter, as well as higher - dimensional nonlinear electromagnetic fields. | arxiv:2111.10387 |
we discover unexpected connections between packing configurations and rare fluctuations in dense systems of active particles subject to pulsation of size. using large deviation theory, we examine biased ensembles which select atypical realizations of the dynamics exhibiting high synchronization in particle size. we show that the order emerging at high bias can manifest as distinct dynamical states featuring high to vanishing pulsation current. remarkably, transitions between these states arise from changing the system geometry at fixed bias and constant density. we rationalize such transitions as arising from the change in packing configurations which, depending on box geometry, may induce highly ordered or geometrically frustrated structures. furthermore, we reveal that a master curve in the unbiased dynamics, correlating polydispersity and current, helps predict the dynamical state emerging in the biased dynamics. finally, we demonstrate that deformation waves can propagate under suitable geometries when biasing with local order. | arxiv:2403.16961 |
we establish strong uniqueness for a class of degenerate sdes of weak h { \ " o } rmander type under suitable h { \ " o } lder regularity conditions for the associated drift term. our approach relies on the zvonkin transform which requires to exhibit good smoothing properties of the underlying parabolic pde with rough, here h { \ " o } lder, drift coefficients and source term. such regularizing effects are established through a perturbation technique ( forward parametrix approach ) which also heavily relies on appropriate duality properties on besov spaces. for the method employed, we exhibit some sharp thresholds on the h { \ " o } lder exponents for the strong uniqueness to hold. | arxiv:1810.12225 |
attractors in asymmetric neural networks with deterministic parallel dynamics were shown to present a " chaotic " regime at symmetry eta < 0. 5, where the average length of the cycles increases exponentially with system size, and an oscillatory regime at high symmetry, where the typical length of the cycles is 2. we show, both with analytic arguments and numerically, that there is a sharp transition, at a critical symmetry $ \ e _ c = 0. 33 $, between a phase where the typical cycles have length 2 and basins of attraction of vanishing weight and a phase where the typical cycles are exponentially long with system size, and the weights of their attraction basins are distributed as in a random map with reversal symmetry. the time - scale after which cycles are reached grows exponentially with system size $ n $, and the exponent vanishes in the symmetric limit, where $ t \ propto n ^ { 2 / 3 } $. the transition can be related to the dynamics of the infinite system ( where cycles are never reached ), using the closing probabilities as a tool. we also study the relaxation of the function $ e ( t ) = - 1 / n \ sum _ i | h _ i ( t ) | $, where $ h _ i $ is the local field experienced by the neuron $ i $. in the symmetric system, it plays the role of a ljapunov function which drives the system towards its minima through steepest descent. this interpretation survives, even if only on the average, also for small asymmetry. this acts like an effective temperature : the larger is the asymmetry, the faster is the relaxation of $ e $, and the higher is the asymptotic value reached. $ e $ reachs very deep minima in the fixed points of the dynamics, which are reached with vanishing probability, and attains a larger value on the typical attractors, which are cycles of length 2. | arxiv:cond-mat/9803224 |
despite remarkable capabilities, large language models ( llms ) struggle to continually update their knowledge without catastrophic forgetting. in contrast, humans effortlessly integrate new information, detect conflicts with existing beliefs, and selectively update their mental models. this paper introduces a cognitive - inspired investigation paradigm to study continual knowledge updating in llms. we implement two key components inspired by human cognition : ( 1 ) dissonance and familiarity awareness, analyzing model behavior to classify information as novel, familiar, or dissonant ; and ( 2 ) targeted network updates, which track neural activity to identify frequently used ( stubborn ) and rarely used ( plastic ) neurons. through carefully designed experiments in controlled settings, we uncover a number of empirical findings demonstrating the potential of this approach. first, dissonance detection is feasible using simple activation and gradient features, suggesting potential for cognitive - inspired training. second, we find that non - dissonant updates largely preserve prior knowledge regardless of targeting strategy, revealing inherent robustness in llm knowledge integration. most critically, we discover that dissonant updates prove catastrophically destructive to the model ' s knowledge base, indiscriminately affecting even information unrelated to the current updates. this suggests fundamental limitations in how neural networks handle contradictions and motivates the need for new approaches to knowledge updating that better mirror human cognitive mechanisms. | arxiv:2502.04390 |
the adsorption of cytosine on the au ( 111 ) and au ( 110 ) surfaces has been studied using both aqueous deposition and evaporation in vacuum to prepare the samples. soft x - ray photoelectron spectroscopy ( xps ) and near edge x - ray absorption fine structure spectroscopy ( nexafs ) were used to determine the electronic structure and orientation of the adsorbates. in addition, three derivatives of cytosine, 6 - azacytosine, 6 - azacytidine and 5 - azacytidine, were studied. monolayer films of the latter three samples were adsorbed on au ( 111 ) from aqueous solution, and the nature of bonding was determined. spectra have been interpreted in the light of published calculations of free cytosine molecules and new ab initio calculations of the other compounds. surface core level shifts of au 4f imply that all of these compounds are chemisorbed. cytosine adsorbs as a single tautomer, but in two chemical states with different surface - molecule bonding. for deposition in vacuum, a flat - lying molecular state bonded through the n ( 3 ) atom of the pyrimidine ring dominates, but a second state is also present. for deposition from solution, the second state dominates, with the molecular plane no longer parallel to the surface. this state also bonds through the n ( 3 ) atom, but in addition interacts with the surface via the amino group. two tautomers of 6 - azacytosine were observed, and they and 6 - azacytidine adsorb with similar geometries, chemically bonding via the azacytosine ring. the ribose ring does not appear to perturb the adsorption of azacytidine compared with azacytosine. the azacytosine ring is nearly but not perfectly parallel to the surface, like 5 - azacytidine, which adsorbs as an imino tautomer.... | arxiv:1305.4432 |
the well known elliptic discrete painlev \ ' e equation of sakai is constructed by a standard translation on the $ e _ 8 ^ { ( 1 ) } $ lattice, given by nearest neighbor vectors. in this paper, we give a new elliptic discrete painlev \ ' e equation obtained by translations along next - nearest - neighbor vectors. this equation is a generic ( 8 - parameter ) version of a 2 - parameter elliptic difference equation found by reduction from adler ' s partial difference equation, the so - called q4 equation. we also provide a projective reduction of the well known equation of sakai. | arxiv:1703.03498 |
we have developed a photonic filter featuring dual independently tunable passbands. employing the reconstruction equivalent - chirp technique, we designed linearly chirped sampled bragg gratings with two equivalent phase shifts positioned at 1 / 3 and 2 / 3 of the cavity, thus introducing two passbands in the + 1st channel. leveraging the significant thermo - optic effect of silicon, dual - band tuning is achieved via micro - heaters integrated on the chip surface. by tuning the injection currents ranging from 0 to 35 ma into the micro - heaters, the filter exhibits a wide range of dual - wavelength filtering performance, with the frequency interval between the two passbands adjustable from 37. 2 ghz to 186. 1 ghz. | arxiv:2410.08248 |
a rank $ n $ generalized baumslag - solitar group is a group that splits as a finite graph of groups such that all vertex and edge groups are isomorphic to $ \ mathbb { z } ^ n $. in this paper we classify these groups in terms of their separability properties. specifically, we determine when they are residually finite, subgroup separable and cyclic subgroup separable. | arxiv:2309.14527 |
the recent observations of microlensing events in the lmc by the macho and eros collaborations suggest that an important fraction of the galactic halo is in the form of massive halo objects ( mho ) of about 0. 1 m _ { \ odot }. here, we argue that the galactic halo is mainly baryonic and that besides mho also h _ 2 molecular clouds may significantly contribute to it. we propose a scenario in which dark clusters of mho and / or h _ 2 molecular clouds form in the halo at galactocentric distances larger than ~ 10 - 20 kpc, since there we expect less collisions among proto globular cluster clouds and a smaller uv radiation flux. cosmic ray protons may induce a significant gamma - ray flux in h _ 2 molecular clouds. our calculation gives an upper bound to this flux which is below present detectability. | arxiv:astro-ph/9411018 |
the fastest quantum algorithms ( for the solution of classical computational tasks ) known so far are basically variations of the hidden subgroup problem with { $ f ( u [ x ] ) = f ( x ) $ }. following a discussion regarding which tasks might be solved efficiently by quantum computers, it will be demonstrated by means of a simple example, that the detection of more general hidden ( two - point ) symmetries { $ v \ { f ( x ), f ( u [ x ] ) \ } = 0 $ } by a quantum algorithm can also admit an exponential speed - up. e. g., one member of this class of symmetries { $ v \ { f ( x ), f ( u [ x ] ) \ } = 0 $ } is discrete self - similarity ( or discrete scale invariance ). pacs : 03. 67. lx, 89. 70. + c. | arxiv:quant-ph/0304090 |
it is well known that a graph is bipartite if and only if the spectrum of its adjacency matrix is symmetric. in the present paper, this assertion is dissected into three separate matrix results of wider scope, which are extended also to hypermatrices. to this end the concept of bipartiteness is generalized by a new monotone property of cubical hypermatrices, called odd - colorable matrices. it is shown that a nonnegative symmetric $ r $ - matrix $ a $ has a symmetric spectrum if and only if $ r $ is even and $ a $ is odd - colorable. this result also solves a problem of pearson and zhang about hypergraphs with symmetric spectrum and disproves a conjecture of zhou, sun, wang, and bu. separately, similar results are obtained for the $ h $ - spectram of hypermatrices. | arxiv:1605.00709 |
despite large language models ( llms ) being known to exhibit bias against non - mainstream varieties, there are no known labeled datasets for sentiment analysis of english. to address this gap, we introduce besstie, a benchmark for sentiment and sarcasm classification for three varieties of english : australian ( en - au ), indian ( en - in ), and british ( en - uk ). using web - based content from two domains, namely, google place reviews and reddit comments, we collect datasets for these language varieties using two methods : location - based and topic - based filtering. native speakers of the language varieties manually annotate the datasets with sentiment and sarcasm labels. to assess whether the dataset accurately represents these varieties, we conduct two validation steps : ( a ) manual annotation of language varieties and ( b ) automatic language variety prediction. subsequently, we fine - tune nine large language models ( llms ) ( representing a range of encoder / decoder and mono / multilingual models ) on these datasets, and evaluate their performance on the two tasks. our results reveal that the models consistently perform better on inner - circle varieties ( i. e., en - au and en - uk ), with significant performance drops for en - in, particularly in sarcasm detection. we also report challenges in cross - variety generalisation, highlighting the need for language variety - specific datasets such as ours. besstie promises to be a useful evaluative benchmark for future research in equitable llms, specifically in terms of language varieties. the besstie datasets, code, and models will be publicly available upon acceptance. | arxiv:2412.04726 |
we consider the problem of constructing a single spanning tree for the single - source buy - at - bulk network design problem for doubling - dimension graphs. we compute a spanning tree to route a set of demands ( or data ) along a graph to or from a designated root node. the demands could be aggregated at ( or symmetrically distributed to ) intermediate nodes where the fusion - cost is specified by a non - negative concave function $ f $. we describe a novel approach for developing an oblivious spanning tree in the sense that it is independent of the number of data sources ( or demands ) and cost function at intermediate nodes. to our knowledge, this is the first paper to propose a single spanning tree solution to this problem ( as opposed to multiple overlay trees ). there has been no prior work where the tree is oblivious to both the fusion cost function and the set of sources ( demands ). we present a deterministic, polynomial - time algorithm for constructing a spanning tree in low doubling graphs that guarantees $ \ log ^ { 3 } d \ cdot \ log n $ - approximation over the optimal cost, where $ d $ is the diameter of the graph and $ n $ the total number of nodes. with constant fusion - cost function our spanning tree gives a $ o ( \ log ^ 3 d ) $ - approximation for every steiner tree to the root. | arxiv:1004.0351 |
we study the canonical injection from the hardy - orlicz space $ h ^ \ psi $ into the bergman - orlicz space $ { \ mathfrak b } ^ \ psi $. | arxiv:1005.1996 |
few - shot graph anomaly detection ( gad ) has recently garnered increasing attention, which aims to discern anomalous patterns among abundant unlabeled test nodes under the guidance of a limited number of labeled training nodes. existing few - shot gad approaches typically adopt meta - training methods trained on richly labeled auxiliary networks to facilitate rapid adaptation to target networks that possess sparse labels. however, these proposed methods often assume that the auxiliary and target networks exist in the same data distributions - an assumption rarely holds in practical settings. this paper explores a more prevalent and complex scenario of cross - domain few - shot gad, where the goal is to identify anomalies within sparsely labeled target graphs using auxiliary graphs from a related, yet distinct domain. the challenge here is nontrivial owing to inherent data distribution discrepancies between the source and target domains, compounded by the uncertainties of sparse labeling in the target domain. in this paper, we propose a simple and effective framework, termed cdfs - gad, specifically designed to tackle the aforementioned challenges. cdfs - gad first introduces a domain - adaptive graph contrastive learning module, which is aimed at enhancing cross - domain feature alignment. then, a prompt tuning module is further designed to extract domain - specific features tailored to each domain. moreover, a domain - adaptive hypersphere classification loss is proposed to enhance the discrimination between normal and anomalous instances under minimal supervision, utilizing domain - sensitive norms. lastly, a self - training strategy is introduced to further refine the predicted scores, enhancing its reliability in few - shot settings. extensive experiments on twelve real - world cross - domain data pairs demonstrate the effectiveness of the proposed cdfs - gad framework in comparison to various existing gad methods. | arxiv:2410.08629 |
in this paper we construct analytically a loff color superconducting state that is both color and charge neutral using the weak coupling approximation. we demonstrate that this state is free from chromomagnetic instabilities. its relevance to the realistic quark matter at moderately high baryon density is discussed. | arxiv:hep-ph/0507306 |
this paper has been withdrawn, see the replacement arxiv : 1302. 6670. | arxiv:1212.3130 |
dark matter ( dm ) may be comprised of axion - like particles ( alps ) with couplings to photons and the standard model fermions. in this paper we study photon signals arising from cosmic ray ( cr ) electron scattering on background alps. for a range of masses we find that these bounds can place competitive new constraints on the alp - electron coupling, although in many models lifetime constraints may supersede these bounds. in addition to current fermi constraints, we also consider future e - astrogram bounds which will have greater sensitivity to alp - cr induced gamma - rays. | arxiv:2012.07930 |
we present the explicit form for all the four dimensional, static, spherically symmetric solutions in $ ( 4 + n ) $ - d abelian kaluza - klein theory by performing a subset of $ so ( 2, n ) $ transformations corresponding to four $ so ( 1, 1 ) $ boosts on the schwarzschild solution, supplemented by $ so ( n ) / so ( n - 2 ) $ transformations. the solutions are parameterized by the mass $ m $, taub - nut charge $ a $, $ n $ electric $ \ vec { \ cal q } $ and $ n $ magnetic $ \ vec { \ cal p } $ charges. non - extreme black holes ( with zero taub - nut charge ) have either the reissner - nordstr \ " om or schwarzschild global space - time. supersymmetric extreme black holes have a null or naked singularity, while non - supersymmetric extreme ones have a global space - time of extreme reissner - nordstr \ " om black holes. | arxiv:hep-th/9503082 |
ornamentations, embellishments, or microtonal inflections are essential to melodic expression across many musical traditions, adding depth, nuance, and emotional impact to performances. recognizing ornamentations in singing voices is key to mir, with potential applications in music pedagogy, singer identification, genre classification, and controlled singing voice generation. however, the lack of annotated datasets and specialized modeling approaches remains a major obstacle for progress in this research area. in this work, we introduce r \ = aga ornamentation detection ( rod ), a novel dataset comprising indian classical music recordings curated by expert musicians. the dataset is annotated using a custom human - in - the - loop tool for six vocal ornaments marked as event - based labels. using this dataset, we develop an ornamentation detection model based on deep time - series analysis, preserving ornament boundaries during the chunking of long audio recordings. we conduct experiments using different train - test configurations within the rod dataset and also evaluate our approach on a separate, manually annotated dataset of indian classical concert recordings. our experimental results support the superior performance of our proposed approach over the baseline crnn. | arxiv:2505.04419 |
previous researches on the information retrieval ( ir ) field have focused on summarizing progress and synthesizing knowledge and techniques from individual studies and data - driven experiments, the extent of contributions and collaborations between researchers from different communities ( e. g., academia and industry ) in advancing ir knowledge remains unclear. to address this gap, this study explores several characteristics of information retrieval research in four areas : productivity patterns and preferred venues, the relationship between citations and downloads, changes in research topics, and changes in patterns of scientific collaboration, by analyzing 53, 471 papers published between 2000 and 2018 from the association for computing machinery ( acm ) digital library dataset. through the analysis and interpretation on empirical datasets, we find that academic research, industry research, and collaborative research between academia and industry focused on different topics. among the collaboration models, academia - industry collaboration is more oriented towards large teamwork. collaborative networks between researchers in academia and industry suggest that the field of information retrieval has become richer over time in terms of themes, foci, and sub - themes, becoming a more diverse field of study. | arxiv:2410.01541 |
we prove comparison principle for viscosity solutions of a hamilton - jacobi - bellman equation in a strong coupling regime considering a stationary and a time - dependent version of the equation. we consider a hamiltonian that has a representation as the supremum of a difference of two functions : an internal hamiltonian depending on a control variable and a function interpreted as a cost of applying the controls. our major innovation lies in the use of a cost function that can be discontinuous, unbounded and depending on momenta, enabling us to address previously unexplored scenarios such as cases arising from the theory of large deviations and homogenisation. for completeness, we also state the existence of viscosity solutions and we verify the assumptions for an example arising from biochemistry. | arxiv:2310.05659 |
in this short note we highlight some of the differences between cube diagrams and grid diagrams. we also list examples of small cube diagrams for all knots up to 7 crossings and give some examples of links. | arxiv:0907.5401 |
we study combinatorial and algorithmic questions around minimal feedback vertex sets in tournament graphs. on the combinatorial side, we derive strong upper and lower bounds on the maximum number of minimal feedback vertex sets in an n - vertex tournament. we prove that every tournament on n vertices has at most 1. 6740 ^ n minimal feedback vertex sets, and that there is an infinite family of tournaments, all having at least 1. 5448 ^ n minimal feedback vertex sets. this improves and extends the bounds of moon ( 1971 ). on the algorithmic side, we design the first polynomial space algorithm that enumerates the minimal feedback vertex sets of a tournament with polynomial delay. the combination of our results yields the fastest known algorithm for finding a minimum size feedback vertex set in a tournament. | arxiv:0905.0567 |
we investigate the tunnel rates and energies of excited states of small numbers of electrons in a quantum dot fabricated in a si / sige heterostructure. tunnel rates for loading and unloading electrons are found to be strongly energy dependent, and they vary significantly between different excited states. we show that this phenomenon enables charge sensing measurements of the average electron occupation that are analogous to coulomb diamonds. excited - state energies can be read directly from the plot, and we develop a rate model that enables a quantitative understanding of the relative sizes of different electron tunnel rates. | arxiv:1010.0972 |
in this review an overview on some recent developments in deformation quantization is given. after a general historical overview we motivate the basic definitions of star products and their equivalences both from a mathematical and a physical point of view. then we focus on two topics : the morita classification of star product algebras and convergence issues which lead to the nuclear weyl algebra. | arxiv:1502.00097 |
ionised gas kinematics provide crucial evidence of the impact that active galactic nuclei ( agn ) have in regulating star formation in their host galaxies. although the presence of outflows in agn host galaxies has been firmly established, the calculation of outflow properties such as mass outflow rates and kinetic energy remains challenging. we present the [ oiii ] 5007 ionised gas outflow properties of 22 z $ < $ 0. 1 x - ray agn, derived from the bat agn spectroscopic survey using muse / vlt. with an average spatial resolution of 1 " ( 0. 1 - 1. 2 kpc ), the observations resolve the ionised gas clouds down to sub - kiloparsec scales. resolved maps show that the [ oiii ] velocity dispersion is, on average, higher in regions ionised by the agn, compared to star formation. we calculate the instantaneous outflow rates in individual muse spaxels by constructing resolved mass outflow rate maps, incorporating variable outflow density and velocity. we compare the instantaneous values with time - averaged outflow rates by placing mock fibres and slits on the muse field - of - view, a method often used in the literature. the instantaneous outflow rates ( 0. 2 - 275 $ m _ { \ odot } $ yr $ ^ { - 1 } $ ) tend to be 2 orders of magnitude higher than the time - averaged outflow rates ( 0. 001 - 40 $ m _ { \ odot } $ yr $ ^ { - 1 } $ ). the outflow rates correlate with the agn bolometric luminosity ( $ l _ { \ rm bol } \ sim $ 10 $ ^ { 42. 71 } $ - 10 $ ^ { 45. 62 } $ erg / s ) but we find no correlations with black hole mass ( 10 $ ^ { 6. 1 } $ - 10 $ ^ { 8. 9 } $ m $ _ { \ odot } $ ), eddington ratio ( 0. 002 - 1. 1 ) and radio luminosity ( 10 $ ^ { 21 } $ - 10 $ ^ { 26 } $ w / hz ). we find the median coupling between the kinetic energy and $ l _ { \ rm bol } $ to be 1 %, consistent with the theoretical predictions for an agn - driven outflow. | arxiv:2201.04149 |
we consider a quasilinear equation given in the half - space, i. e. a so called boundary reaction problem. our concerns are a geometric poincar \ ' e inequality and, as a byproduct of this inequality, a result on the symmetry of low - dimensional bounded stable solutions, under some suitable assumptions on the nonlinearities. more precisely, we analyze the following boundary problem $ $ \ left \ { \ begin { matrix } - { \ rm div } ( a ( x, | \ nabla u | ) \ nabla u ) + g ( x, u ) = 0 \ qquad { on $ \ r ^ n \ times ( 0, + \ infty ) $ } - a ( x, | \ nabla u | ) u _ x = f ( u ) \ qquad { \ mbox { on $ \ r ^ n \ times \ { 0 \ } $ } } \ end { matrix } \ right. $ $ under some natural assumptions on the diffusion coefficient $ a ( x, | \ nabla u | ) $ and the nonlinearities $ f $ and $ g $. here, $ u = u ( y, x ) $, with $ y \ in \ r ^ n $ and $ x \ in ( 0, + \ infty ) $. this type of pde can be seen as a nonlocal problem on the boundary $ \ partial \ r ^ { n + 1 } _ + $. the assumptions on $ a ( x, | \ nabla u | ) $ allow to treat in a unified way the $ p - $ laplacian and the minimal surface operators. | arxiv:0803.1382 |
we present the discovery of several ultra compact dwarfs ( ucds ) located in field / group environments. examination of these objects, plus literature objects, confirms the existence of two distinct formation channels for ucds. we find that the ucds we have discovered around the group elliptical ngc3923 ( and ucds generally ) have properties consistent with their being the most luminous members of the host galaxy ' s globular cluster ( gc ) system. we describe ucds of this type as giant gcs ( ggcs ). in contrast, the ucd we have found associated with the isolated s0 ngc4546 is clearly the result of the stripping of a nucleated companion galaxy. the young age ( ~ 3. 4 gyr ) of the ucd, the lack of a correspondingly young gc population, the apparently short dynamical friction decay timescale ( ~ 0. 5 gyr ) of the ucd, and the presence of a counterrotating gas disc in the host galaxy ( co - rotating with the ucd ) together suggest that this ucd is the liberated nucleus remaining after the recent stripping of a companion by ngc4546. we suggest a general scheme that unifies the formation of gcs, ucds, and galaxy nuclei. in this picture " normal " gcs are a composite population, composed of gcs formed in situ, gcs acquired from accreted galaxies, and a population of lower mass stripped dwarf nuclei masquerading as gcs. above a " scaling onset mass " of 2x10 ^ 6 msun ( mv ~ - 10 ), ucds emerge together with a mass - size relation and a likely mass - metallicity relation ( the " blue tilt " ). in the mass range up to 7x10 ^ 7 msun ( mv ~ - 13 ) ucds comprise a composite population of ggcs and stripped nuclei. above 7x10 ^ 7 msun, ucds must be almost exclusively stripped nuclei, as no sufficiently rich gc systems exist to populate such an extreme of the gclf. | arxiv:1102.0001 |
quantum signal processing ( qsp ) has emerged as a promising framework to manipulate and determine properties of quantum systems. qsp not only unifies most existing quantum algorithms but also provides tools to discover new ones. quantum signal processing is applicable to single - or multi - qubit systems that can be qubitized so one can exploit the su $ ( 2 ) $ structure of system evolution within special invariant two - dimensional subspaces. in the context of quantum algorithms, this su $ ( 2 ) $ structure is artificially imposed on the system through highly nonlocal evolution operators that are difficult to implement on near - term quantum devices. in this work, we propose qsp protocols for the infinite - dimensional onsager lie algebra, which is relevant to the physical dynamics of quantum devices that can simulate the transverse field ising model. to this end, we consider qsp sequences in the heisenberg picture, allowing us to exploit the emergent su $ ( 2 ) $ structure in momentum space and synthesize qsp sequences for the onsager algebra. our results demonstrate a concrete connection between qsp techniques and noisy intermediate scale quantum protocols. we provide examples and applications of our approach in diverse fields ranging from space - time dual quantum circuits and quantum simulation, to quantum control. | arxiv:2309.04538 |
pragmatic trials evaluating health care interventions often adopt cluster randomization due to scientific or logistical considerations. previous reviews have shown that co - primary endpoints are common in pragmatic trials but infrequently recognized in sample size or power calculations. while methods for power analysis based on $ k $ ( $ k \ geq 2 $ ) binary co - primary endpoints are available for crts, to our knowledge, methods for continuous co - primary endpoints are not yet available. assuming a multivariate linear mixed model that accounts for multiple types of intraclass correlation coefficients ( endpoint - specific iccs, intra - subject iccs and inter - subject between - endpoint iccs ) among the observations in each cluster, we derive the closed - form joint distribution of $ k $ treatment effect estimators to facilitate sample size and power determination with different types of null hypotheses under equal cluster sizes. we characterize the relationship between the power of each test and different types of correlation parameters. we further relax the equal cluster size assumption and approximate the joint distribution of the $ k $ treatment effect estimators through the mean and coefficient of variation of cluster sizes. our simulation studies with a finite number of clusters indicate that the predicted power by our method agrees well with the empirical power, when the parameters in the multivariate linear mixed model are estimated via the expectation - maximization algorithm. an application to a real crt is presented to illustrate the proposed method. | arxiv:2112.01981 |
a framework and method are proposed for the study of constituent composition in fmri. the method produces estimates of neural patterns encoding complex linguistic structures, under the assumption that the contributions of individual constituents are additive. like usual techniques for modeling compositional structure in fmri, the proposed method employs pattern superposition to synthesize complex structures from their parts. unlike these techniques, superpositions are sensitive to the structural positions of constituents, making them irreducible to structure - indiscriminate ( " bag - of - words " ) models of composition. reanalyzing data from a study by frankland and greene ( 2015 ), it is shown that comparison of neural predictive models with differing specifications can illuminate aspects of neural representational contents that are not apparent when composition is not modelled. the results indicate that the neural instantiations of the binding of fillers to thematic roles in a sentence are non - orthogonal, and therefore spatially overlapping. | arxiv:2110.12342 |
based on the microlensing variability of the two - image gravitational lens he1104 - 1805 observed between 0. 4 and 8 microns, we have measured the size and wavelength - dependent structure of the quasar accretion disk. modeled as a power law in temperature, t proportional to r ^ - beta, we measure a b - band ( 0. 13 microns in the rest frame ) half - light radius of r _ { 1 / 2, b } = 6. 7 ( + 6. 2 - 3. 2 ) x 10 ^ 15 cm ( 68 % cl ) and a logarithmic slope of beta = 0. 61 ( + 0. 21 - 0. 17 ) for our standard model with a logarithmic prior on the disk size. both the scale and the slope are consistent with simple thin disk models where beta = 3 / 4 and r _ { 1 / 2, b } = 5. 9 x 10 ^ 15 cm for a shakura - sunyaev disk radiating at the eddington limit with 10 % efficiency. the observed fluxes favor a slightly shallower slope, beta = 0. 55 ( + 0. 03 - 0. 02 ), and a significantly smaller size for beta = 3 / 4. | arxiv:0707.0003 |
we study the dynamics of post - critically finite endomorphisms of p ^ k ( c ). we prove that post - critically finite endomorphisms are always post - critically finite all the way down under a mild regularity condition on the post - critical set. we study the eigenvalues of periodic points of post - critically finite endomorphisms. then, under a weak transversality condition and assuming kobayashi hyperbolicity of the complement of the post - critical set, we prove that the only possible fatou components are super - attracting basins, thus partially extending to any dimension a result of fornaess - sibony and rong holding in the case k = 2. | arxiv:1609.02717 |
let $ x $ be a compact k \ " ahler manifold and $ \ a \ in h ^ { 1, 1 } ( x, \ r ) $ a k \ " ahler class. we study the metric completion of the space $ \ hh _ \ a $ of k \ " ahler metrics in $ \ a $, when endowed with the mabuchi $ l ^ 2 $ - metric $ d $. using recent ideas of darvas, we show that the metric completion $ ( \ overline { \ hh } _ \ a, d ) $ of $ ( \ hh _ \ a, d ) $ is a cat ( 0 ) space which can be identified with $ \ e ^ 2 ( \ a ) $, a subset of the class $ \ e ^ 1 ( \ a ) $ of positive closed currents with finite energy. we further prove, in the toric setting, that $ \ overline { \ hh } _ { \ a, tor } = \ e _ { tor } ^ 2 ( \ a ) $. | arxiv:1401.7857 |
efficient collection of fluorescence from trapped ions is crucial for quantum optics and quantum computing applications, specifically, for qubit state detection and in generating single photons for ion - photon and remote ion entanglement. in a typical setup, only a few per cent of ion fluorescence is intercepted by the aperture of the imaging optics. we employ a simple metallic spherical mirror integrated with a linear paul ion trap to achieve photon collection efficiency of at least 10 % from a single ba $ ^ + $ ion. an aspheric corrector is used to reduce the aberrations caused by the mirror and achieve high image quality. | arxiv:0911.4958 |
this is the first paper in a series that studies smooth relative lie algebra homologies and cohomologies based on the theory of formal manifolds and formal lie groups. in this paper, we lay the foundations for this study by introducing the notion of formal manifolds in the context of differential geometry, inspired by the notion of formal schemes in algebraic geometry. we develop the basic theory for formal manifolds, and establish a fully faithful contravariant functor from the category of formal manifolds to the category of topological $ \ mathbb { c } $ - algebras. we also prove the existence of finite products in the category of formal manifolds by studying vector - valued formal functions. | arxiv:2401.01535 |
a kaluza - klein model, with a matter source associated with hawking radiation from an evaporating black hole, is used to obtain a simple form for the radion effective potential. the environmental effect generally causes a matter - induced shift of the radion vacuum, resulting in the formation of a radion cloud around the hole. there is an albedo due to the radion cloud, with an energy dependent reflection coefficient that depends upon the size of the extra dimensions and the temperature of the hole. | arxiv:0909.0693 |
any loop qcd amplitude at full colour is constructed from kinematic and gauge - group building blocks. in a unitarity - based on - shell framework, both objects can be reconstructed from their respective counterparts in tree - level amplitudes. this procedure is at its most powerful when aligned with flexible colour decompositions of tree - level qcd amplitudes. in this note we derive such decompositions for amplitudes with an arbitrary number of quarks and gluons from the same principle that is used to bootstrap kinematics - unitarity factorisation. in the process we formulate new multi - quark bases and provide closed - form expressions for the new decompositions. we then elaborate upon their application in colour decompositions of loop multi - quark amplitudes. | arxiv:1908.02695 |
with the advent of modern data collection and storage technologies, data - driven approaches have been developed for discovering the governing partial differential equations ( pde ) of physical problems. however, in the extant works the model parameters in the equations are either assumed to be known or have a linear dependency. therefore, most of the realistic physical processes cannot be identified with the current data - driven pde discovery approaches. in this study, an innovative framework is developed that combines data - driven and data - assimilation methods for simultaneously identifying physical processes and inferring model parameters. spatiotemporal measurement data are first divided into a training data set and a testing data set. using the training data set, a data - driven method is developed to learn the governing equation of the considered physical problem by identifying the occurred ( or dominated ) processes and selecting the proper empirical model. through introducing a prediction error of the learned governing equation for the testing data set, a data - assimilation method is devised to estimate the uncertain model parameters of the selected empirical model. for the contaminant transport problem investigated, the results demonstrate that the proposed method can adequately identify the considered physical processes via concurrently discovering the corresponding governing equations and inferring uncertain parameters of nonlinear models, even in the presence of measurement errors. this work helps to broaden the applicable area of the research of data driven discovery of governing equations of physical problems. | arxiv:1810.11977 |
we study hst / nicmos h - band images of bulges of two equal - sized samples of early - ( t ( rc3 ) < 4 ) and late - type spiral ( mainly sbc - sc ) galaxies matched in outer disk axis ratio. we find that bulges of late - type spirals are more elongated than their counterparts in early - type spirals. using a ks - test we find that the two distributions are different at the 98. 4 % confidence level. we conclude that the two data sets are different, i. e. late - type galaxies have a broader ellipticity distribution and contain more elongated features in the inner regions. we discuss the possibility that these would correspond to bars at a later evolutionary stage, i. e. secularly evolved bars. consequent implications are raised, and we discuss relevant questions regarding the formation and structure of bulges. are bulges of early - type and late - type spirals different? are their formation scenarios different? can we talk about bulges in the same way for different types of galaxies? | arxiv:astro-ph/0305326 |
we examine the relation between the szekeres models and relativistic lagrangian perturbation schemes, in particular the relativistic zel ' dovich approximation ( rza ). we show that the second class of the szekeres solutions is exactly contained within the rza when the latter is restricted to an irrotational dust source with a flow - orthogonal foliation of spacetime. in such a case, the solution is governed by the first principal scalar invariant of the deformation field, proving a direct connection with a class of newtonian three - dimensional solutions without symmetry. for the second class, a necessary and sufficient condition for the vanishing of cosmological backreaction on a scale of homogeneity is expressed through integral constraints. domains with no backreaction can be smoothly matched, forming a lattice model, where exact deviations average out at a given scale of homogeneity, and the homogeneous and isotropic background is recovered as an average property of the model. although the connection with the first class of szekeres solutions is not straightforward, this class allows for the interpretation in terms of a spatial superposition of nonintersecting fluid lines, where each world line evolves independently and under the rza model equations, but with different associated ` local backgrounds '. this points to the possibility of generalizing the lagrangian perturbation schemes to structure formation models on evolving backgrounds, including global cosmological backreaction. | arxiv:2009.06339 |
we present a many - body calculation of the band structure and optical spectrum of the layered hybrid organic - inorganic halide perovskites in the ruddlesden - popper phase with the general formula a $ ^ { ' } _ { 2 } $ a $ _ { n - 1 } $ m $ _ { n } $ x $ _ { 3n + 1 } $, focusing specifically on the lead iodide family. we calculate the mean - field band structure with spin - orbit coupling, quasiparticle corrections within the gw approximation, and optical spectra using the bethe - salpeter equation. the model is parameterized by first - principles calculations and classical electrostatic screening, enabling an accurate but cost - effective study of large unit cells and corresponding thickness - dependent properties. a transition of the electronic and optical properties from quasi - two - dimensional behavior to three - dimensional behavior is shown for increasing $ n $ and the nonhydrogenic character of the excitonic rydberg series is analyzed. the thickness - dependent 1s and 2s exciton energy levels are in good agreement with recently reported experiments and the 1s exciton binding energy is calculated to be 302 mev for $ n = 1 $, 97 mev for $ n = 5 $, and 37 mev for $ n = \ infty $ ( bulk mapbi3 ). | arxiv:1908.09436 |
we have analyzed the magnetic effects that may occur in rapidly rotating core collapse supernovae. we consider effects from both magnetic turbulence and the formation of magnetic bubbles. for magnetic turbulence we have made a perturbative analysis for our spherically symmetric core - collapse supernova model that incorporates the build up of magnetic field energy in the matter accreting onto the proto - neutron star shortly after collapse and bounce. this significantly modifies the pressure profile and increases the heating of the material above the proto - neutron star resulting in an explosion even in rotating stars that would not explode otherwise. regarding magnetic bubbles we show that a model with a modest initial uniform magnetic field and uniform angular velocity of ~ 0. 1 rad / s can form magnetic bubbles due to the very non homologous nature of the collapse. it is estimated that the buoyancy of the bubbles causes matter in the proto - neutron star to rise, carrying neutrino - rich material to the neutron - star surface. this increases the neutrino luminosity sufficiently at early times to achieve a successful neutrino - driven explosion. both magnetic mechanisms thus provide new means for initiating a type ii core - collapse supernova. | arxiv:astro-ph/0508146 |
in this paper, we explore the relationship between the topological characteristics of a complex network and its robustness to sustained targeted attacks. using synthesised scale - free, small - world and random networks, we look at a number of network measures, including assortativity, modularity, average path length, clustering coefficient, rich club profiles and scale - free exponent ( where applicable ) of a network, and how each of these influence the robustness of a network under targeted attacks. we use an established robustness coefficient to measure topological robustness, and consider sustained targeted attacks by order of node degree. with respect to scale - free networks, we show that assortativity, modularity and average path length have a positive correlation with network robustness, whereas clustering coefficient has a negative correlation. we did not find any correlation between scale - free exponent and robustness, or rich - club profiles and robustness. the robustness of small - world networks on the other hand, show substantial positive correlations with assortativity, modularity, clustering coefficient and average path length. in comparison, the robustness of erdos - renyi random networks did not have any significant correlation with any of the network properties considered. a significant observation is that high clustering decreases topological robustness in scale - free networks, yet it increases topological robustness in small - world networks. our results highlight the importance of topological characteristics in influencing network robustness, and illustrate design strategies network designers can use to increase the robustness of scale - free and small - world networks under sustained targeted attacks. | arxiv:1402.6489 |
psr b0628 - 28 is a radio pulsar which was first detected in the x - ray band by rosat and then later observed with chandra and xmm - newton. the chandra observation yielded an x - ray luminosity two orders of magnitude higher than what is expected for spin - powered pulsars, also there were no pulsations detected. the xmm - newton observation, however, reveals pulsations at the expected radio period, p = 1. 244 s. the simultaneously analyzed spectra also gives a luminosity ( in cgs ) log lx = 30. 34, which is ~ 350 times greater than what would be expected from the correlation between lx - edot. | arxiv:astro-ph/0505461 |
we propose to detect the mott insulator - superfluid quantum phase transition in an array of coupled cavities by studying the polariton and photon fluctuations in a block of linear dimension m ( in units of the lattice constant of the array ). we explicitly show this for a one - dimensional array ; the analysis can be however extended to higher dimensions. in the mott phase polariton fluctuations are independent of the block size. in the superfluid phase they grow logarithmically with m, the prefactor being related to the compressibility of the system. in the case of photon fluctuations, the critical behaviour is encoded in the subleading scaling with the block dimension, while the leading behaviour is linear in m and non - critical. our results have been obtained by means of the density matrix renormalization group numerical algorithm. | arxiv:0806.0942 |
we study a graph coloring problem that is otherwise easy but becomes quite non - trivial in the one - pass streaming model. in contrast to previous graph coloring problems in streaming that try to find an assignment of colors to vertices, our main work is on estimating the number of conflicting or monochromatic edges given a coloring function that is streaming along with the graph ; we call the problem { \ sc conflict - est }. the coloring function on a vertex can be read or accessed only when the vertex is revealed in the stream. if we need the color on a vertex that has streamed past, then that color, along with its vertex, has to be stored explicitly. we provide algorithms for a graph that is streaming in different variants of the one - pass vertex arrival streaming model, viz. the { \ sc vertex arrival } ( { \ sc va } ), { vertex arrival with degree oracle } ( { \ sc vadeg } ), { \ sc vertex arrival in random order } ( { \ sc varand } ) models, with special focus on the random order model. we also provide matching lower bounds for most of the cases. the mainstay of our work is in showing that the properties of a random order stream can be exploited to design streaming algorithms for estimating the number of conflicting edges. we have also obtained a lower bound, though not matching the upper bound, for the random order model. among all the three models vis - a - vis this problem, we can show a clear separation of power in favor of the { \ sc varand } model. | arxiv:2010.13143 |
in this letter, we propose an algorithm for recovery of sparse and low rank components of matrices using an iterative method with adaptive thresholding. in each iteration, the low rank and sparse components are obtained using a thresholding operator. this algorithm is fast and can be implemented easily. we compare it with one of the most common fast methods in which the rank and sparsity are approximated by $ \ ell _ 1 $ norm. we also apply it to some real applications where the noise is not so sparse. the simulation results show that it has a suitable performance with low run - time. | arxiv:1703.03722 |
the baryon acoustic oscillation ( bao ) feature in the two - point correlation function of galaxies supplies a standard ruler to probe the expansion history of the universe. we study here several galaxy selection schemes, aiming at building an emission - line galaxy ( elg ) sample in the redshift range $ 0. 6 < z < 1. 7 $, that would be suitable for future bao studies, providing a highly biased galaxy sample. we analyse the angular galaxy clustering of galaxy selections at the redshifts 0. 5, 0. 7, 0. 8, 1 and 1. 2 and we combine this analysis with a halo occupation distribution ( hod ) model to derive the properties of the haloes these galaxies inhabit, in particular the galaxy bias on large scales. we also perform a weak lensing analysis ( aperture statistics ) to extract the galaxy bias and the cross - correlation coefficient and compare to the hod prediction. we apply this analysis on a data set composed of the photometry of the deep co - addition on sloan digital sky survey ( sdss ) stripe 82 ( 225 deg $ ^ 2 $ ), of canda - france - hawai telescope / stripe 82 deep \ emph { i } - band weak lensing survey and of the { \ it wide - field infrared survey explorer } infrared photometric band w1. the analysis on the sdss - iii / constant mass galaxies selection at $ z = 0. 5 $ is in agreement with previous studies on the tracer, moreover we measure its cross - correlation coefficient $ r = 1. 16 \ pm0. 35 $. for the higher redshift bins, we confirm the trends that the brightest galaxy populations selected are strongly biased ( $ b > 1. 5 $ ), but we are limited by current data sets depth to derive precise values of the galaxy bias. a survey using such tracers of the mass field will guarantee a high significance detection of the bao. | arxiv:1302.5655 |
fast and safe motion is crucial for the successful deployment of physically interactive robots. parallel robots ( prs ) offer the potential for higher speeds while maintaining the same energy limits due to their low moving masses. however, they require methods for contact detection and reaction while avoiding singularities and self - collisions. we address this issue and present safepr - a unified approach for the detection and localization, including the distinction between collision and clamping to perform a reaction that is safe for humans and feasible for prs. our approach uses information from the encoders and motor currents to estimate forces via a generalized - momentum observer. neural networks and particle filters classify and localize the contacts. we introduce reactions with redundancy resolution to avoid type - ii singularities and self - collisions. our approach detected and terminated 72 real - world collision and clamping contacts with end - effector speeds of up to 1. 5 m / s, each within 25 - 275 ms. the forces were below the thresholds from iso / ts 15066. by using built - in sensors, safepr enables safe interaction with already assembled prs without the need for new hardware components. | arxiv:2501.17773 |
low - complexity models such as linear function representation play a pivotal role in enabling sample - efficient reinforcement learning ( rl ). the current paper pertains to a scenario with value - based linear representation, which postulates the linear realizability of the optimal q - function ( also called the " linear $ q ^ { \ star } $ problem " ). while linear realizability alone does not allow for sample - efficient solutions in general, the presence of a large sub - optimality gap is a potential game changer, depending on the sampling mechanism in use. informally, sample efficiency is achievable with a large sub - optimality gap when a generative model is available but is unfortunately infeasible when we turn to standard online rl settings. in this paper, we make progress towards understanding this linear $ q ^ { \ star } $ problem by investigating a new sampling protocol, which draws samples in an online / exploratory fashion but allows one to backtrack and revisit previous states in a controlled and infrequent manner. this protocol is more flexible than the standard online rl setting, while being practically relevant and far more restrictive than the generative model. we develop an algorithm tailored to this setting, achieving a sample complexity that scales polynomially with the feature dimension, the horizon, and the inverse sub - optimality gap, but not the size of the state / action space. our findings underscore the fundamental interplay between sampling protocols and low - complexity structural representation in rl. | arxiv:2105.08024 |
years from clinical adoption ; however, there is a growing effort to expand this time - horizon over which clinical engineers can influence the trajectory of biomedical innovation. in their various roles, they form a " bridge " between the primary designers and the end - users, by combining the perspectives of being both close to the point - of - use, while also trained in product and process engineering. clinical engineering departments will sometimes hire not just biomedical engineers, but also industrial / systems engineers to help address operations research / optimization, human factors, cost analysis, etc. also, see safety engineering for a discussion of the procedures used to design safe systems. the clinical engineering department is constructed with a manager, supervisor, engineer, and technician. one engineer per eighty beds in the hospital is the ratio. clinical engineers are also authorized to audit pharmaceutical and associated stores to monitor fda recalls of invasive items. = = rehabilitation engineering = = rehabilitation engineering is the systematic application of engineering sciences to design, develop, adapt, test, evaluate, apply, and distribute technological solutions to problems confronted by individuals with disabilities. functional areas addressed through rehabilitation engineering may include mobility, communications, hearing, vision, and cognition, and activities associated with employment, independent living, education, and integration into the community. while some rehabilitation engineers have master ' s degrees in rehabilitation engineering, usually a subspecialty of biomedical engineering, most rehabilitation engineers have an undergraduate or graduate degrees in biomedical engineering, mechanical engineering, or electrical engineering. a portuguese university provides an undergraduate degree and a master ' s degree in rehabilitation engineering and accessibility. qualification to become a rehab ' engineer in the uk is possible via a university bsc honours degree course such as health design & technology institute, coventry university. the rehabilitation process for people with disabilities often entails the design of assistive devices such as walking aids intended to promote the inclusion of their users into the mainstream of society, commerce, and recreation. = = regulatory issues = = regulatory issues have been constantly increased in the last decades to respond to the many incidents caused by devices to patients. for example, from 2008 to 2011, in us, there were 119 fda recalls of medical devices classified as class i. according to u. s. food and drug administration ( fda ), class i recall is associated to " a situation in which there is a reasonable probability that the use of, or exposure to, a product will cause serious adverse health consequences or death " regardless of the country - specific legislation, the main regulatory objectives coincide worldwide. for example, in the medical device regulations, a product must be 1 | https://en.wikipedia.org/wiki/Biomedical_engineering |
in bismuth ferrite ( bifeo3 ), antiferromagnetic and ferroelectric order coexist at room temperature, making it of particular interest for studying magnetoelectric coupling. the mutual control of magnetic and electric properties is very useful for a wide variety of applications. this has led to an enormous amount of research into the properties of bifeo $ _ 3 $. nonetheless, one of the most fundamental aspects of this material, namely the symmetries of the lattice vibrations, remains controversial. we present a comprehensive raman study of bifeo $ _ 3 $ single crystals with the approach of monitoring the raman spectra while rotating the polarization direction of the excitation laser. our method results in unambiguous assignment of the phonon symmetries and explains the origin of the controversy in the literature. furthermore, it provides access to the raman tensor elements enabling direct comparison with theoretical calculations. hence, this allows the study of symmetry breaking and coupling mechanisms in a wide range of complex materials and may lead to a noninvasive, all - optical method to determine the orientation and magnitude of the ferroelectric polarization. | arxiv:1207.4799 |
by means of an adapted mean - field expansion for large fillings $ n \ gg1 $, we study the evolution of quantum fluctuations in the time - dependent bose - hubbard model, starting in the superfluid state and approaching the mott phase by decreasing the tunneling rate or increasing the interaction strength in time. for experimentally relevant cases, we derive analytical results for the temporal behavior of the number and phase fluctuations, respectively. this allows us to calculate the growth of the quantum depletion and the decay of off - diagonal long - range order. we estimate the conditions for the observability of the time dependence in the correlation functions in the experimental setups with external trapping present. finally, we discuss the analogy to quantum effects in the early universe during the inflationary epoch. | arxiv:0711.4729 |
to safeguard civilian global navigation satellite systems ( gnss ) external information available to the platform encompassing the gnss receiver can be used to detect attacks. cross - checking the gnss - provided time against alternative multiple trusted time sources can lead to attack detection aiming at controlling the gnss receiver time. leveraging external, network - connected secure time providers and onboard clock references, we achieve detection even under fine - grained time attacks. we provide an extensive evaluation of our multi - layered defense against adversaries mounting attacks against the gnss receiver along with controlling the network link. we implement adversaries spanning from simplistic spoofers to advanced ones synchronized with the gnss constellation. we demonstrate attack detection is possible in all tested cases ( sharp discontinuity, smooth take - over, and coordinated network manipulation ) without changes to the structure of the gnss receiver. leveraging the diversity of the reference time sources, detection of take - over time push as low as 150us is possible. smooth take - overs forcing variations as low as 30ns are also detected based on on - board precision oscillators. the method ( and thus the evaluation ) is largely agnostic to the satellite constellation and the attacker type, making time - based data validation of gnss information compatible with existing receivers and readily deployable. | arxiv:2502.03868 |
we compute the next - to - leading order qcd and electroweak corrections to $ z $ and $ w $ pole observables using the dimension - 6 standard model effective field theory and present numerical results that can easily be included in global fitting programs. limits on smeft coefficient functions are presented at leading order and at next - to - leading order under several assumptions. | arxiv:1909.02000 |
natural and human - made disasters have dramatically increased during the last decades. given the strong relationship between first responders localization time and the final number of deaths, the modernization of search - and - rescue operations has become imperative. in this context, unmanned aerial vehicles ( uavs ) - based solutions are the most promising candidates to take up on the localization challenge by leveraging on emerging technologies such as : artificial intelligence ( ai ), reconfigurable intelligent surfaces ( ris ) and orthogonal time frequency space ( otfs ) modulations. in this paper, we capitalize on such recently available techniques by shedding light on the main challenges and future opportunities to boost the localization performance of state - of - the - art techniques to give birth to unprecedentedly effective missing victims localization solutions. | arxiv:2109.03180 |
the advanced x - ray imaging satellite ( axis ) is a nasa probe class mission concept designed to deliver arcsecond resolution with an effective area ten times that of chandra ( at launch ). the axis focal plane features an mit lincoln laboratory ( mit - ll ) x - ray charge - coupled device ( ccd ) detector working in conjunction with an application specific integrated circuit ( asic ), denoted the multi - channel readout chip ( mcrc ). while this readout asic targets the axis mission, it is applicable to a range of potential x - ray missions with comparable readout requirements. designed by the x - ray astronomy and observational cosmology ( xoc ) group at stanford university, the mcrc asic prototype ( mcrc - v1. 0 ) uses a 350 nm technology node and provides 8 channels of high speed, low noise, low power consumption readout electronics. each channel implements a current source to bias the detector output driver, a preamplifier to provide gain, and an output buffer to interface directly to an analog - to - digital ( adc ) converter. the mcrc - v1 asic exhibits comparable performance to our best discrete electronics implementations, but with ten times less power consumption and a fraction of the footprint area. in a total ionizing dose ( tid ) test, the chip demonstrated a radiation hardness equal or greater to 25 krad, confirming the suitability of the process technology and layout techniques used in its design. the next iteration of the asic ( mcrc - v2 ) will expand the channel count and extend the interfaces to external circuits, advancing its readiness as a readout - on - a - chip solution for next generation x - ray ccd - like detectors. this paper summarizes our most recent characterization efforts, including the tid radiation campaign and results from the first operation of the mcrc asic in combination with a representative mit - ll ccd. | arxiv:2407.16759 |
after the decade - long exhaustive study of binary high - tc superconducting hydrides, the frontier of this stimulating research field has recently shifted to ternary hydrides with much expanded conformational space in search of coveted room - temperature superconductors. this task, however, presents a formidable challenge due to enormous demands on computational resources. here, we devise an efficient high - throughput approach using keen material insights and a self - built database to screen for robust ternary hydrides in clathrate structures, which were proven to host highest tc in binary hydrides, and to estimate tc by a reliable empirical formula. this approach has made it possible to uncover a diverse set of complex multiple - hydrogen - cage ternary hydrides hosting near or above room - temperature tc, which are beyond the reach of prevailing structure search methods. this study establishes a distinct paradigm that opens a fresh avenue to enable and accelerate the discovery of promising room - temperature superconductors among unprecedented complex clathrate hydrides. | arxiv:2412.13431 |
in minkowski geometry the unit ball is a compact convex body $ k $ containing the origin in its interior. the boundary of the body is formed by the unit vectors. we also have a so - called minkowski functional to measure the length of vectors. by changing the origin in the interior of the body we have a smoothly varying family of minkowski functionals. this is called the funk metric. under some regularity conditions the minkowski functionals allow us to measure the volume ( area ) of the indicatrix bodies ( hypersurfaces ). some homogenity properties provide the volume and the area to be proportional. the area as the function of the base point varying in the interior of $ k $ is strictly convex [ 25 ]. this is called the area function of the funk manifold. if the minimum is attained at the origin then $ k $ is said to be balanced. the idea comes from the generalization of brickell ' s theorem [ 6 ] for finsler manifolds with balanced indicatrices [ 25 ]. as a continuation of [ 25 ] we are going to investigate analytic properties and the asymptotic behavior of the area function of a funk manifold. we prove that the area function is locally analytic and the area can be arbitrary large near to the boundary of $ k $. therefore the minimum always attained at a uniquely determined interior point of $ k $. if we apply the result to the indicatrices of a finsler manifold point by point then the uniquely defined minima of the area functions constitute a vector field. we prove that it is differentiable. therefore each indicatrix body can be translated in such a way that the translated body is balanced and we always have an associated finsler manifold with balanced indicatrices. finsler manifolds having balanced indicatrices represent a class of finsler spaces such that the so - called brickell ' s conjecture holds [ 6 ], see also [ 25 ]. | arxiv:1602.06565 |
we present the results of a deep wide - field near - infrared survey of 12 square degrees of the pleiades conducted as part of the ukidss deep infrared sky survey ( ukidss ) galactic cluster survey ( gcs ). we have extracted over 340 high probability proper motion members down to 0. 03 solar masses using a combination of ukidss photometry and proper motion measurements obtained by cross - correlating the gcs with data from the two micron all sky survey ( 2mass ), the isaac newton ( int ) and the canada - france - hawai ' i ( cfht ) telescopes. additionally, we have unearthed 73 new candidate brown dwarf members on the basis of five band ukidss photometry alone. we have identified 23 substellar multiple system candidates out of 63 candidate brown dwarfs from the ( y - k, y ) and ( j - k, j ) colour - magnitude diagrams, yielding a binary frequency of 28 - 44 % in the 0. 075 - 0. 030 msun mass range. our estimate is three times larger than the binary fractions reported from high - resolution imaging surveys of field ultracool dwarfs and pleiades brown dwarfs. however, it is marginally consistent with our earlier ` ` peculiar ' ' photometric binary fraction of 50 + / - 10 % presented in pinfield et al. ( 2003 ), in good agreement with the 32 - 45 % binary fraction derived from the recent monte - carlo simulations of maxted & jeffries ( 2005 ) and compatible with the 26 + / - 10 % frequency recently estimated by basri & reiners ( 2006 ). a tentative estimate of the mass ratios from photometry alone seems to support the hypothesis that binary brown dwarfs tend to reside in near equal - mass ratio systems. ( abridged ) | arxiv:0706.2234 |
in this paper we study existence of solutions for the cauchy problem of the debye - h \ " { u } ckel system with low regularity initial data. by using the chemin - lerner time - space estimate for the heat equation, we prove that there exists a unique local solution if the initial data belongs to the besov space $ \ dot { b } ^ { s } _ { p, q } ( \ mathbb { r } ^ { n } ) $ for $ - 3 / 2 < s \ leq - 2 + \ frac { n } { 2 } $, $ p = \ frac { n } { s + 2 } $ and $ 1 \ leq q \ leq \ infty $, and furthermore, if the initial data is sufficiently small then the solution is global. this result improves the regularity index of the initial data space in previous results on this model. | arxiv:1105.3844 |
generating natural and expressive human motions from textual descriptions is challenging due to the complexity of coordinating full - body dynamics and capturing nuanced motion patterns over extended sequences that accurately reflect the given text. to address this, we introduce bipo, bidirectional partial occlusion network for text - to - motion synthesis, a novel model that enhances text - to - motion synthesis by integrating part - based generation with a bidirectional autoregressive architecture. this integration allows bipo to consider both past and future contexts during generation while enhancing detailed control over individual body parts without requiring ground - truth motion length. to relax the interdependency among body parts caused by the integration, we devise the partial occlusion technique, which probabilistically occludes the certain motion part information during training. in our comprehensive experiments, bipo achieves state - of - the - art performance on the humanml3d dataset, outperforming recent methods such as parco, momask, and bamm in terms of fid scores and overall motion quality. notably, bipo excels not only in the text - to - motion generation task but also in motion editing tasks that synthesize motion based on partially generated motion sequences and textual descriptions. these results reveal the bipo ' s effectiveness in advancing text - to - motion synthesis and its potential for practical applications. | arxiv:2412.00112 |
we calculate the inverse beta decay ( ibd ) antineutrino spectrum generated by nuclear reactors using the summation method to understand deviations from the smooth huber - mueller model due to the decay of individual fission products, showing that plotting the ratio of two adjacent spectra points can effectively reveal these deviations. we obtained that for binning energies of 0. 1 mev or lower, abrupt changes in the spectra due to the jagged nature of the individual antineutrino spectra could be observed for highly precise experiments. surprisingly, our calculations also reveal a peak - like feature in the adjacent points ratio plot at 4. 5 mev even with a 0. 25 mev binning interval, which we find is present in the ibd daya bay spectrum published in 2016. we show that this 4. 5 mev feature is caused by the contributions of just four fission products, 95y, 98, 101n and 102tc. this would be the first evidence of the decay of a few fission products in the ibd antineutrino spectrum from a nuclear reactor. | arxiv:1710.00092 |
the edelweiss programme is dedicated to the direct search for dark matter as massive weakly interacting particles ( wimps ) with germanium cryogenic detectors operated in the laboratoire souterrain de modane in the french alps at a depth of 4800 mwe. after the initial phase edelweiss i, which involved a total mass of 1 kg, the second step of the programme, edelweiss ii, currently operates 9 kg of detectors and an active shielding of 100 m ^ 2 muon veto detectors and is now in its commissioning phase. the current status and performance of the edelweiss ii set - up in terms of backgrounds will be given, the underground muon flux measured with the muon veto system will be presented. | arxiv:0710.5849 |
we discuss the physics of crystals with small polydispersity near the jamming transition point. for this purpose, we introduce an effective single - particle model taking into account the nearest neighbor structure of crystals. the model can be solved analytically by using the replica method in the limit of large dimensions. in the absence of polydispersity, the replica symmetric solution is stable until the jamming transition point, which leads to the standard scaling of perfect crystals. on the contrary, for finite polydispersity, the model undergoes the full replica symmetry breaking ( rsb ) transition before the jamming transition point. in the rsb phase, the model exhibits the same scaling as amorphous solids near the jamming transition point. these results are fully consistent with the recent numerical simulations of crystals with polydispersity. the simplicity of the model also allows us to derive the scaling behavior of the vibrational density of states that can be tested in future experiments and numerical simulations. | arxiv:1910.14285 |
we study the phase diagram of the spin - 3 / 2 blume - emery - griffiths model on a honeycomb lattice by monte carlo simulations in order to verify the presence of some peculiar features predicted by the effective field theory ( eft ) with correlations. the locations of the order - disorder phase boundaries are estimated from thermal variations of the magnetic susceptibility curves. it is found that for positive values of the biquadratic interactions the critical boundary shows a discontinuous character as a function of the single - ion anisotropy strength, in line with the eft expectations. however, for negative values of the biquadratic interactions the step - like variation of the critical frontier predicted by eft was not reproduced. | arxiv:1309.3588 |
a generalized definition of quantum stochastic ( qs ) integrals and differentials is given in the free of adaptiveness and basis form in terms of malliavin derivative on a projective fock scale, and their uniform continuity and qs differentiability with respect to the inductive limit convergence is proved. a new form of qs calculus based on an inductive * - algebraic structure in an indefinite space is developed and a nonadaptive generalization of the qs ito formula for its representation in fock space is derived. the problem of solution of general qs evolution equations in a hilbert space is solved in terms of the constructed operator representation of chronological products, defined in the indefinite space, and the unitary and * - homomorphism property respectively for operators and maps of these solutions, corresponding to the pseudounitary and * - homomorphism property of the qs integrable generators, is proved. | arxiv:math-ph/0512076 |
many natural markov chains fail to mix to their stationary distribution in polynomially many steps. often, this slow mixing is inevitable since it is computationally intractable to sample from their stationary measure. nevertheless, markov chains can be shown to always converge quickly to measures that are locally stationary, i. e., measures that don ' t change over a small number of steps. these locally stationary measures are analogous to local minima in continuous optimization, while stationary measures correspond to global minima. while locally stationary measures can be statistically far from stationary measures, do they enjoy provable theoretical guarantees that have algorithmic implications? we study this question in this work and demonstrate three algorithmic applications of locally stationary measures : 1. we show that glauber dynamics on the hardcore model can be used to find independent sets of size $ \ omega \ left ( \ frac { \ log d } { d } \ cdot n \ right ) $ in triangle - free graphs of degree at most $ d $. 2. let $ w $ be a symmetric real matrix with bounded spectral diameter and $ v $ be a unit vector. given the matrix $ m = \ lambda vv ^ \ top + w $ with a planted rank - one spike along vector $ v $, for sufficiently large constant $ \ lambda $, glauber dynamics on the ising model defined by $ m $ samples vectors $ x \ in \ { \ pm 1 \ } ^ n $ that have constant correlation with the vector $ v $. 3. let $ m = a _ { \ mathbf { g } } - \ frac { d } { n } \ mathbf { 1 } \ mathbf { 1 } ^ \ top $ be a centered version of the adjacency matrix where the graph $ \ mathbf { g } $ is drawn from a sparse 2 - community stochastic block model. we show that for sufficiently large constant signal - to - noise ratio, glauber dynamics on the ising model defined by $ m $ samples vectors $ x \ in \ { \ pm 1 \ } ^ n $ that have constant correlation with the hidden community vector $ \ mathbf { \ sigma } $. | arxiv:2405.20849 |
hall, bert s. ( 1979 ), the technological illustrations of the so - called " anonymous of the hussite wars ". codex latinus monacensis 197, part 1, wiesbaden : dr. ludwig reichert verlag, isbn 3 - 920153 - 93 - 6 lancaster, lynne ( 1999 ), " building trajan ' s column ", american journal of archaeology, 103 ( 3 ) : 419 – 439, doi : 10. 2307 / 506969, jstor 506969, s2cid 192986322 man, john ( 2002 ), the gutenberg revolution : the story of a genius and an invention that changed the world, london : headline review, isbn 978 - 0 - 7472 - 4504 - 9 mcluhan, marshall ( 1962 ), the gutenberg galaxy : the making of typographic man ( 1st ed. ), university of toronto press, isbn 978 - 0 - 8020 - 6041 - 9 { { citation } } : isbn / date incompatibility ( help ) ritti, tullia ; grewe, klaus ; kessener, paul ( 2007 ), " a relief of a water - powered stone saw mill on a sarcophagus at hierapolis and its implications ", journal of roman archaeology, 20 : 138 – 163, doi : 10. 1017 / s1047759400005341, s2cid 161937987 sarton, george ( 1946 ), " floating docks in the sixteenth century ", isis, 36 ( 3 / 4 ) : 153 – 154, doi : 10. 1086 / 347934, s2cid 144849113 stimson, alan ( 1985 ), the mariner ' s astrolabe. a survey of 48 surviving examples, coimbra : uc biblioteca geral weber, johannes ( 2006 ), " strassburg, 1605 : the origins of the newspaper in europe ", german history, 24 ( 3 ) : 387 – 412, doi : 10. 1191 / 0266355406gh380oa white, lynn jr. ( 1962 ), medieval technology and social change, oxford : at the clarendon press white, lynn jr. ( 1968 ), " the invention of the parachute ", technology and culture, 9 ( 3 ) : 462 – 467, doi : 10. 2307 / 3101655, | https://en.wikipedia.org/wiki/Renaissance_technology |
we investigate the dynamical properties of liquid and supercooled liquid silicon, modeled using the stillinger - weber ( sw ) potential, to examine the validity of the stokes - einstein ( se ) relation. towards this end, we examine the relationship among various dynamical quantities, including ( i ) the macroscopic transport coefficients - self diffusion coefficient $ d $ and viscosity $ \ eta $, ( ii ) relaxation time $ \ tau _ { \ alpha } $ as well as ( iii ) lengthscale dependent relaxation times $ \ tau _ { \ alpha } ( q ) $ over a broad range of temperature $ t $, pressure $ p $ and density $ \ rho $ covering both equilibrium and metastable liquid state points in the phase diagram. our study shows a weak break down in se relation involving $ d $ and $ \ eta $, and the loci of \ revision { the breakdown of the se relation } ( seb ) is found in the high t liquid phase. the $ \ tau _ { \ alpha } $, when used as a proxy to $ \ eta $, shows distinct breakdown in the se relation whose loci is found in the supercooled liquid phase. interestingly, certain parts of the phase diagram shows that loci of onset of slow dynamics lie below the loci of seb, suggesting a regime that exhibits arrhenius but non - fickian behaviour. computation of $ \ tau _ { \ alpha } ( q ) $ enables us to extract the lengthscale associated with the fickian to non - fickian behaviour using which we show that the \ revision { breakdown of the se relation } occurs only below a specific lengthscale at a given temperature. further we also compare the seb loci with other features of the phase behaviour, including the loci of compressiblity maximum, density maximum as well as diffusivity maximum. | arxiv:2503.18498 |
the 2015 outburst of v404 cygni is an unusual one with several x - ray and radio flares and rapid variation in the spectral and timing properties. the outburst occurred after $ 26 $ years of inactivity of the black hole. we study the accretion flow properties of the source during its initial phase of the outburst using { \ it swift } / xrt and { \ it swift } / bat data in the energy range of $ 0. 5 - 150 $ kev. we have done spectral analysis with the two - component advective flow ( tcaf ) model fits file. several flow parameters such as two types of accretion rates ( keplerian disk and sub - keplerian halo ), shock parameters ( location and compression ratio ) are extracted to understand the accretion flow dynamics. we calculated equipartition magnetic field $ b $ for the outburst and found that the highest $ b \ sim 900 $ ~ gauss. power density spectra ( pds ) showed no break, which indicates no or very less contribution of the keplerian disk component, which is also seen from the result of the spectral analysis. no signature of prominent quasi - periodic oscillations ( qpos ) is observed in the pds. this is due to the mismatch of the cooling timescale and infall timescale of the post - shock matter. | arxiv:2006.03310 |
we present light3r - sfm, a feed - forward, end - to - end learnable framework for efficient large - scale structure - from - motion ( sfm ) from unconstrained image collections. unlike existing sfm solutions that rely on costly matching and global optimization to achieve accurate 3d reconstructions, light3r - sfm addresses this limitation through a novel latent global alignment module. this module replaces traditional global optimization with a learnable attention mechanism, effectively capturing multi - view constraints across images for robust and precise camera pose estimation. light3r - sfm constructs a sparse scene graph via retrieval - score - guided shortest path tree to dramatically reduce memory usage and computational overhead compared to the naive approach. extensive experiments demonstrate that light3r - sfm achieves competitive accuracy while significantly reducing runtime, making it ideal for 3d reconstruction tasks in real - world applications with a runtime constraint. this work pioneers a data - driven, feed - forward sfm approach, paving the way toward scalable, accurate, and efficient 3d reconstruction in the wild. | arxiv:2501.14914 |
we study the morphology of the richest superclusters from the catalogues of superclusters of galaxies in the 2df galaxy redshift survey and compare the morphology of real superclusters with model superclusters in the millennium simulation. we use minkowski functionals and shapefinders to quantify the morphology of superclusters : their sizes, shapes, and clumpiness. we generate empirical models of simple geometry to understand which morphologies correspond to the supercluster shapefinders. we show that rich superclusters have elongated, filamentary shapes with high - density clumps in their core regions. the clumpiness of superclusters is determined using the fourth minkowski functional $ v _ 3 $. in the $ k _ 1 $ - $ k _ 2 $ shapefinder plane the morphology of superclusters is described by a curve which is characteristic to multi - branching filaments. we also find that the differences between the fourth minkowski functional $ v _ 3 $ for the bright and faint galaxies in observed superclusters are larger than in simulated superclusters. | arxiv:0706.1122 |
a diffusion model, which is formulated to produce an image using thousands of denoising steps, usually suffers from a slow inference speed. existing acceleration algorithms simplify the sampling by skipping most steps yet exhibit considerable performance degradation. by viewing the generation of diffusion models as a discretized integrating process, we argue that the quality drop is partly caused by applying an inaccurate integral direction to a timestep interval. to rectify this issue, we propose a timestep aligner that helps find a more accurate integral direction for a particular interval at the minimum cost. specifically, at each denoising step, we replace the original parameterization by conditioning the network on a new timestep, which is obtained by aligning the sampling distribution to the real distribution. extensive experiments show that our plug - in design can be trained efficiently and boost the inference performance of various state - of - the - art acceleration methods, especially when there are few denoising steps. for example, when using 10 denoising steps on the popular lsun bedroom dataset, we improve the fid of ddim from 9. 65 to 6. 07, simply by adopting our method for a more appropriate set of timesteps. code will be made publicly available. | arxiv:2310.09469 |
large language models ( llms ) learn a vast amount of knowledge during pretraining, but they are often oblivious to the source ( s ) of such knowledge. we investigate the problem of intrinsic source citation, where llms are required to cite the pretraining source supporting a generated response. intrinsic source citation can enhance llm transparency, interpretability, and verifiability. to give llms such ability, we explore source - aware training - - a recipe that involves ( i ) training the llm to associate unique source document identifiers with the knowledge in each document, followed by ( ii ) an instruction - tuning stage to teach the llm to cite a supporting pretraining source when prompted. source - aware training borrows from existing pretraining / fine - tuning frameworks and requires minimal changes to the model architecture or implementation. through experiments on synthetic data, we demonstrate that our training recipe can enable faithful attribution to the pretraining data without a substantial impact on the model ' s perplexity compared to standard pretraining. our findings also highlight the importance of pretraining data augmentation in achieving attribution. code and data available here : \ url { https : / / github. com / mukhal / intrinsic - source - citation } | arxiv:2404.01019 |
abundance of stable charged massive particles ( champs ) is severely constrained by their searches inside sea water. we examine whether inflation with low reheat temperature can sufficiently dilute the abundance to evade this severe bound on champs, by taking into account their production and annihilation in a plasma during reheating phase. we argue that the abundance of the champs with mass less than 1 tev will exceed the experimental bound, ruling out these champs, especially the possibility of the superpartner of tau lepton as the stable lightest superparticle. on the other hand, it is found that the champ much heavier than 1 tev can survive the bound, if the reheat temperature is low enough. | arxiv:hep-ph/0103272 |
in this paper, we examine the work of data annotation. specifically, we focus on the role of counting or quantification in organising annotation work. based on an ethnographic study of data annotation in two outsourcing centres in india, we observe that counting practices and its associated logics are an integral part of day - to - day annotation activities. in particular, we call attention to the presumption of total countability observed in annotation - the notion that everything, from tasks, datasets and deliverables, to workers, work time, quality and performance, can be managed by applying the logics of counting. to examine this, we draw on sociological and socio - technical scholarship on quantification and develop the lens of a ' regime of counting ' that makes explicit the specific counts, practices, actors and structures that underpin the pervasive counting in annotation. we find that within the ai supply chain and data work, counting regimes aid the assertion of authority by the ai clients ( also called requesters ) over annotation processes, constituting them as reductive, standardised, and homogenous. we illustrate how this has implications for i ) how annotation work and workers get valued, ii ) the role human discretion plays in annotation, and iii ) broader efforts to introduce accountable and more just practices in ai. through these implications, we illustrate the limits of operating within the logic of total countability. instead, we argue for a view of counting as partial - located in distinct geographies, shaped by specific interests and accountable in only limited ways. this, we propose, sets the stage for a fundamentally different orientation to counting and what counts in data annotation. | arxiv:2311.18046 |
we propose unsupervised episode generation method called neighbors as queries ( naq ) to solve the few - shot node - classification ( fsnc ) task by unsupervised graph meta - learning. doing so enables full utilization of the information of all nodes in a graph, which is not possible in current supervised meta - learning methods for fsnc due to the label - scarcity problem. in addition, unlike unsupervised graph contrastive learning ( gcl ) methods that overlook the downstream task to be solved at the training phase resulting in vulnerability to class imbalance of a graph, we adopt the episodic learning framework that allows the model to be aware of the downstream task format, i. e., fsnc. the proposed naq is a simple but effective unsupervised episode generation method that randomly samples nodes from a graph to make a support set, followed by similarity - based sampling of nodes to make the corresponding query set. since naq is model - agnostic, any existing supervised graph meta - learning methods can be trained in an unsupervised manner, while not sacrificing much of their performance or sometimes even improving them. extensive experimental results demonstrate the effectiveness of our proposed unsupervised episode generation method for graph meta - learning towards the fsnc task. our code is available at : https : / / github. com / jhngjng / naq - pytorch. | arxiv:2306.15217 |
the covid - 19 pandemic has caused unprecedented disruption, particularly in retail. where essential demand cannot be fulfilled online, or where more stringent measures have been relaxed, customers must visit shop premises in person. this naturally gives rise to some risk of susceptible individuals ( customers or staff ) becoming infected. it is essential to minimise this risk as far as possible while retaining economic viability of the shop. we therefore explore and compare the spread of covid - 19 in different shopping situations involving person - to - person interactions : ( i ) free - flowing, unstructured shopping ; ( ii ) structured shopping ( e. g. a queue ). we examine which of ( i ) or ( ii ) may be preferable for minimising the spread of covid - 19 in a given shop, subject to constraints such as the geometry of the shop ; compliance of the population to local guidelines ; and additional safety measures which may be available to the organisers of the shop. we derive a series of conclusions, such as unidirectional free movement being preferable to bidirectional shopping, and that the number of servers should be maximised as long as they can be well protected from infection. | arxiv:2011.09277 |
the inferential model ( im ) approach, like fiducial and its generalizations, depends on a representation of the data - generating process. here, a particular variation on the im construction is considered, one based on generalized associations. the resulting generalized im is more flexible than the basic im in that it does not require a complete specification of the data - generating process and is provably valid under mild conditions. computation and marginalization strategies are discussed, and two applications of this generalized im approach are presented. | arxiv:1511.06733 |
patient portal allows discharged patients to access their personalized discharge instructions in electronic health records ( ehrs ). however, many patients have difficulty understanding or memorizing their discharge instructions. in this paper, we present paniniqa, a patient - centric interactive question answering system designed to help patients understand their discharge instructions. paniniqa first identifies important clinical content from patients ' discharge instructions and then formulates patient - specific educational questions. in addition, paniniqa is also equipped with answer verification functionality to provide timely feedback to correct patients ' misunderstandings. our comprehensive automatic and human evaluation results demonstrate our paniniqa is capable of improving patients ' mastery of their medical instructions through effective interactions | arxiv:2308.03253 |
tetraquarks qqq * q * are found to be described remarkably well with the quantum chromodynamics version of the hydrogen bond, as treated with the born - oppenheimer approximation. we show the robustness of the method by computing the mass of the observed tcc tetraquark following two different paths. relying on this, we provide a prediction for the mass of the expected tbb particle. the average sizes of tetraquarks are estimated to be approximately 3 - 5 gev * * - 1. as a consequence hyperfine separations are not expected to be sizeable. we discussed possible reasons why lhcb has observed only one state in the dd * spectrum. | arxiv:2208.02730 |
we present simple graph - theoretic characterizations of cayley graphs for monoids, semigroups and groups. we extend these characterizations to commutative monoids, semilattices, and abelian groups. | arxiv:1903.06521 |
direct reciprocity based on the repeated prisoner ' s dilemma has been intensively studied. most theoretical investigations have concentrated on memory - $ 1 $ strategies, a class of elementary strategies just reacting to the previous - round outcomes. though the properties of " all - or - none " strategies ( $ aon _ k $ ) have been discovered, simulations just confirmed the good performance of $ aon _ k $ of very short memory lengths. it remains unclear how $ aon _ k $ strategies would fare when players have access to longer rounds of history information. we construct a theoretical model to investigate the performance of the class of $ aon _ k $ strategies of varying memory length $ k $. we rigorously derive the payoffs and show that $ aon _ k $ strategies of intermediate memory length $ k $ are most prevalent, while strategies of larger memory lengths are less competent. larger memory lengths make it hard for $ aon _ k $ strategies to coordinate, and thus inhibiting their mutual reciprocity. we then propose the adaptive coordination strategy combining tolerance and $ aon _ k $ ' coordination rule. this strategy behaves like $ aon _ k $ strategy when coordination is not sufficient, and tolerates opponents ' occasional deviations by still cooperating when coordination is sufficient. we found that the adaptive coordination strategy wins over other classic memory - $ 1 $ strategies in various typical competition environments, and stabilizes the population at high levels of cooperation, suggesting the effectiveness of high level adaptability in resolving social dilemmas. our work may offer a theoretical framework for exploring complex strategies using history information, which are different from traditional memory - $ n $ strategies. | arxiv:2403.03497 |
two cycles on a projective variety over an algebraically closed field are shown to be rationally equivalent if and only if their difference equals a difference of complete intersections of a certain kind. some of bloch ' s conjectures for zero - cycles on surfaces can be restated more geometrically, which leads to several questions. | arxiv:alg-geom/9608015 |
the \ textsc { mg - mamposst } code is a license - free \ textsc { fortran95 } code to perform tests of general relativity ( gr ) through the analyses of kinematical data of galaxy clusters based on the jeans ' equation. the code is based on the \ textsc { mamposst } method, and extends the original code through new parametrisations of the gravitational potential for general families of gravity theories beyond gr aimed to explain dark energy. \ textsc { mg - mamposst } is further supplemented with a new capability to produce weak lensing forecasts for joint kinematic + lensing analysis. this document provides a technical description of the code ' s new features, functionality with respect to the original version, and instructions on its installation and use. finally, we explain how the code could be further modified to include a wider family of gravity models and / or density profiles, that could allow its application in broader theoretical frameworks as well as other physical systems such as stellar clusters. a detailed forecast analysis for the modified gravity models currently implemented in the code can be found in the paper of pizzuti et al., 2021. | arxiv:2201.07194 |
user interface ( ui ) prototyping is a necessary step in the early stages of application development. transforming sketches of a graphical user interface ( ui ) into a coded ui application is an uninspired but time - consuming task performed by a ui designer. an automated system that can replace human efforts for straightforward implementation of ui designs will greatly speed up this procedure. the works that propose such a system primarily focus on using ui wireframes as input rather than hand - drawn sketches. in this paper, we put forward a novel approach wherein we employ a deep neural network that is trained on our custom database of such sketches to detect ui elements in the input sketch. detection of objects in sketches is a peculiar visual recognition task that requires a specific solution that our deep neural network model attempts to provide. the output from the network is a platform - independent ui representation object. the ui representation object is a dictionary of key - value pairs to represent the ui elements recognized along with their properties. this is further consumed by our ui parser which creates code for different platforms. the intrinsic platform - independence allows the model to create a ui prototype for multiple platforms with single training. this two - step approach without the need for two trained models improves over other methods giving time - efficient results ( average time : 129 ms ) with good accuracy. | arxiv:1910.08930 |
the spin - orbit mott insulator sr3ir2o7 provides a fascinating playground to explore insulator - metal transition driven by intertwined charge, spin, and lattice degrees of freedom. here, we report high pressure electric resistance and resonant inelastic x ray scattering measurements on single crystal sr3ir2o7 up to 63 65 gpa at 300 k. the material becomes a confined metal at 59. 5 gpa, showing metallicity in the ab plane but an insulating behavior along the c axis. such an unusual phenomenon resembles the strange metal phase in cuprate superconductors. since there is no sign of the collapse of spin orbit or coulomb interactions in x - ray measurements, this novel insulator metal transition is potentially driven by a first - order structural change at nearby pressures. our discovery points to a new approach for synthesizing functional materials. | arxiv:1605.07582 |
a key event in the history of the milky way is the formation of the bar. this event affects the subsequent structural and dynamical evolution of the entire galaxy. when the bar formed, gas was likely rapidly funnelled to the centre of the galaxy settling in a star - forming nuclear disc. the milky way bar formation can then be dated by considering the oldest stars in the formed nuclear stellar disc. in this highly obscured and crowded region, reliable age tracers are limited, but bright, high - amplitude mira variables make useful age indicators as they follow a period - - age relation. we fit dynamical models to the proper motions of a sample of mira variables in the milky way ' s nuclear stellar disc region. weak evidence for inside - out growth and both radial and vertical dynamical heating with time of the nuclear stellar disc is presented suggesting the nuclear stellar disc is dynamically well - mixed. furthermore, for mira variables around a $ \ sim350 $ day period, there is a clear transition from nuclear stellar disc - dominated kinematics to background bar - bulge - dominated kinematics. using a mira variable period - age relation calibrated in the solar neighbourhood, this suggests the nuclear stellar disc formed in a significant burst in star formation $ ( 8 \ pm 1 ) \, \ mathrm { gyr } $ ago, although the data are also weakly consistent with a more gradual formation of the nuclear stellar disc at even earlier epochs. this implies a relatively early formation time for the milky way bar ( $ \ gtrsim8 \, \ mathrm { gyr } $ ), which has implications for the growth and state of the young milky way and its subsequent history. | arxiv:2311.00035 |
to search for low - redshift damped lyman - alpha ( dla ) and sub - dla quasar absorbers, we have conducted a 21cm absorption survey of radio - loud quasars at small impact parameters to foreground galaxies selected from the sloan digital sky survey ( sdss ). here we present the first results from this survey based on observations of sdss j104257. 58 + 074850. 5 ( $ z _ { qso } $ = 2. 66521 ), a quasar at an angular separation from a foreground galaxy ( $ z _ { gal } $ = 0. 03321 ) of 2. 5 " ( 1. 7 kpc in projection ). the foreground galaxy is a low - luminosity spiral with on - going star formation ( 0. 004 m $ _ { \ odot } $ yr $ ^ { - 1 } $ kpc $ ^ { - 2 } $ ) and a metallicity of $ - 0. 27 \ pm 0. 05 $ dex. we detect 21cm absorption from the galaxy with the green bank telescope ( gbt ), the very large array ( vla ), and the very long baseline array ( vlba ). the absorption appears to be quiescent disk gas corotating with the galaxy and we do not find any evidence for outflowing cold neutral gas. the width of the main absorption line indicates that the gas is cold, $ t _ { k } < 283 $ k, and the hi column is surprisingly low given the impact parameter of 1. 7 kpc ; we find that n ( hi ) $ \ leq 9. 6 \ times 10 ^ { 19 } $ cm $ ^ { - 2 } $ ( gbt ) and n ( hi ) $ \ leq 1. 5 \ times 10 ^ { 20 } $ cm $ ^ { - 2 } $ ( vlba ). vlba marginally resolves the continuum source and the absorber, and a lower limit of 27. 1 $ \ times $ 13. 9 pc is derived for the size of the absorbing cloud. in turn, this indicates a low density for a cold cloud, n ( hi ) $ < $ 3. 5 cm $ ^ { - 3 } $. we hypothesize that this galaxy, which is relatively isolated, is becoming depleted in hi because it is converting its interstellar matter into stars without a replenishing source of gas, | arxiv:0912.2575 |
this work presents a novel breast cancer imaging approach that uses compressive sensing in a hybrid digital breast tomosynthesis ( dbt ) / nearfield radar imaging ( nri ) system configuration. the non - homogeneous tissue distribution of the breast, described in terms of dielectric constant and conductivity, is extracted from the dbt image, and it is used by a full - wave finite difference in the frequency domain ( fdfd ) method to build a linearized model of the non - linear nri imaging problem. the inversion of the linear problem is solved using compressive sensing imaging techniques, which lead to a reduction on the required number of sensing antennas and operational bandwidth without loss of performance. | arxiv:1603.06151 |
motivated by experimental suggestions of anionic redox processes helping to design higher energy lithium ion - battery cathode materials, we investigate this effect using first - principles electronic structure calculations for li - rich layered sulfides. we identify the determination of the energetic contribution of intra - atomic hund ' s exchange coupling as a major obstacle to a reliable theoretical description. we overcome this challenge by developing a particularly efficient flavor of charge - self - consistent combined density functional + dynamical mean - field theory ( dft + dmft ) calculations. our scheme allows us to describe the spin ground states of the transition metal d shell, the electronic structure of the materials, and its energetics. as a result of the high - spin to low - spin transition the average intercalation voltage shows intriguing non - monotonic behavior. we rationalize these findings by an analysis of the fluctuations of spin and charge degrees of freedom. our work demonstrates the relevance of most recent insights into correlated electron materials for the physics of functional materials such as li - ion battery compounds. | arxiv:2305.08526 |
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