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we study distributions of meeting times for finite symmetric markov chains. for markov kernels defined on large state spaces which satisfy certain weak inhomogeneity in return probabilities of points up to large numbers of steps, we obtain approximation, with explicit error bounds, of the laplace transforms of some meeting times ( without scaling ) by ratios of green functions closely related to hitting times of points. in studying this approximation, we identify some key matrix power series in markov kernels weighted with solutions to a discrete transport - like equation with explicit coefficients, which stems from the viewpoint that meeting time distributions are equivalent to correlations of some linear particle system. our result applies in particular to random walks on large random regular graphs. it gives a justification of the corresponding practice, among other things, in allen, traulsen, tarnita and nowak ( 2012 ) on approximating certain critical values for the emergence of cooperation when mutation is present.
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arxiv:1410.4716
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in this paper, a novel approach for coding nominal data is proposed. for the given nominal data, a rank in a form of complex number is assigned. the proposed method does not lose any information about the attribute and brings other properties previously unknown. the approach based on these knew properties can been used for classification. the analyzed example shows that classification with the use of coded nominal data or both numerical as well as coded nominal data is more effective than the classification, which uses only numerical data.
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arxiv:1601.01966
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the application of photonics to astronomy offers major advantages in the area of highly - multiplexed spectroscopy, especially when applied to extremely large telescopes. these include the suppression of the near - infrared night - sky spectrum [ j. bland - hawthorn et al, opt. express 12, 5902 ( 2004 ), s. g. leon - saval et al, opt. lett. 30, 2545 ( 2005 ) ] and the miniaturisation of spectrographs so that they may integrated into the light - path of individual spatial samples [ j. bland - hawthorn et al, proc spie 6269, 62690n ( 2006 ) ]. efficient collection of light from the telescope requires multimode optical fibres and three - dimensional photonic devices. we propose ultrafast laser inscription ( uli ) [ r. r. thomson et al, opt. express 15, 11691 ( 2007 ) ] as the best technology to fabricate 3d photonic devices for astrophotonic applications.
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arxiv:0908.1325
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we make a systematic calculation for polarized vector meson production in semi - inclusive lepton - nucleon deep inelastic scattering $ e ^ - n \ to e ^ - vx $. we consider the general case of neutral current electroweak interactions at high energies which give rise to parity - violating effects. we present a general kinematic analysis for the process and show that the cross sections are expressed by 81 structure functions. we further give a parton model calculation for the process and show the results for the structure functions in terms of the transverse momentum dependent parton distribution functions and fragmentation functions at the leading order and leading twist of perturbative quantum chromodynamics. the results show that there are 27 nonzero structure functions at this order, among which 15 are related to the tensor polarization of the vector meson. thirteen structure functions are generated by parity - violating effects. we also present the result and a rough numerical estimate for the spin alignment of the vector meson.
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arxiv:2201.02511
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in this letter, we contribute a multi - language handwritten digit recognition dataset named mnist - mix, which is the largest dataset of the same type in terms of both languages and data samples. with the same data format with mnist, mnist - mix can be seamlessly applied in existing studies for handwritten digit recognition. by introducing digits from 10 different languages, mnist - mix becomes a more challenging dataset and its imbalanced classification requires a better design of models. we also present the results of applying a lenet model which is pre - trained on mnist as the baseline.
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arxiv:2004.03848
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designing a quantum key agreement ( qka ) protocol is always a challenging task, because both the security and the fairness properties have to be considered simultaneously. recently, zhu et al. ( quantum inf process 14 ( 11 ) : 4245 - 4254 ) pointed out that shukla et al. ' s qka protocol ( quantum inf process 13 ( 11 ) : 2391 - 2405 ) has some security flaws ( which lead to the participant attack ). moreover, they proposed an improvement to avoid these weaknesses. however this study points out that the improved protocol also suffers from a colluding attack, i. e., two dishonest participants in the protocol can collaborate to manipulate the final secret key without being detected.
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arxiv:1510.08249
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in a combinatorial communication system, some signals consist of the combinations of other signals. such systems are more efficient than equivalent, non - combinatorial systems, yet despite this they are rare in nature. why? previous explanations have focused on the adaptive limits of combinatorial communication, or on its purported cognitive difficulties, but neither of these explains the full distribution of combinatorial communication in the natural world. here we present a nonlinear dynamical model of the emergence of combinatorial communication that, unlike previous models, considers how initially non - communicative behaviour evolves to take on a communicative function. we derive three basic principles about the emergence of combinatorial communication. we hence show that the interdependence of signals and responses places significant constraints on the historical pathways by which combinatorial signals might emerge, to the extent that anything other than the most simple form of combinatorial communication is extremely unlikely. we also argue that these constraints can be bypassed if individuals have the socio - cognitive capacity to engage in ostensive communication. humans, but probably no other species, have this ability. this may explain why language, which is massively combinatorial, is such an extreme exception to nature ' s general trend for non - combinatorial communication.
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arxiv:1308.4780
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recent high - angular - resolution ( up to 0. 7 " ) dust polarization observations toward star forming regions are summarized. with the sub - millimeter array, the emission from the dense structures is traced and resolved. the detected magnetic field morphologies vary from hourglass - like structures to isolated patches depending on the evolutionary stage of the source. these observed features have also served as a testbed to develop new analysis methods, with a particular focus on quantifying the role of the magnetic field in the star formation process.
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arxiv:1202.4635
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we investigate the phenomenology of the mssm extended by a single r - parity violating coupling at the unification scale. for all r - parity violating couplings, we discuss the evolution of the particle spectra through the renormalization group equations and the nature of the lightest supersymmetric particle ( lsp ) within the cmssm, as an example of a specific complete supersymmetric model. we use the nature of the lsp to classify the possible signatures. for each possible scenario we present in detail the current lhc bounds on the supersymmetric particle masses, typically obtained using simplified models. from this we determine the present coverage of r - parity violating models at the lhc. we find several gaps, in particular for a stau - lsp, which is easily obtained in r - parity violating models. using the program checkmate we recast existing lhc searches to set limits on the parameters of all r - parity violating cmssms. we find that virtually all of them are either more strongly constrained or similarly constrained in comparison to the r - parity conserving cmssm, including the $ \ bar u \ bar d \ bar d $ models. for each r - parity violating cmssm we then give the explicit lower mass bounds on all relevant supersymmetric particles.
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arxiv:1706.09418
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most primates live in social groups which survival and stability depend on individuals ' abilities to create strong social relationships with other group members. the existence of those groups requires to identify individuals and to assign to each of them a social status. individual recognition can be achieved through vocalizations but also through faces. in humans, an efficient system for the processing of own species faces exists. this specialization is achieved through experience with faces of conspecifics during development and leads to the loss of ability to process faces from other primate species. we hypothesize that a similar mechanism exists in social primates. we investigated face processing in one old world species ( genus macaca ) and in one new world species ( genus cebus ). our results show the same advantage for own species face recognition for all tested subjects. this work suggests in all species tested the existence of a common trait inherited from the primate ancestor : an efficient system to identify individual faces of own species only.
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arxiv:q-bio/0702020
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for argumentation mining, there are several sub - tasks such as argumentation component type classification, relation classification. existing research tends to solve such sub - tasks separately, but ignore the close relation between them. in this paper, we present a joint framework incorporating logical relation between sub - tasks to improve the performance of argumentation structure generation. we design an objective function to combine the predictions from individual models for each sub - task and solve the problem with some constraints constructed from background knowledge. we evaluate our proposed model on two public corpora and the experiment results show that our model can outperform the baseline that uses a separate model significantly for each sub - task. our model also shows advantages on component - related sub - tasks compared to a state - of - the - art joint model based on the evidence graph.
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arxiv:1701.05343
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fisher vector has been widely used in many multimedia retrieval and visual recognition applications with good performance. however, the computation complexity prevents its usage in real - time video monitoring. in this work, we proposed and implemented gpu - fv, a fast fisher vector extraction method with the help of modern gpus. the challenge of implementing fisher vector on gpus lies in the data dependency in feature extraction and expensive memory access in fisher vector computing. to handle these challenges, we carefully designed gpu - fv in a way that utilizes the computing power of gpu as much as possible, and applied optimizations such as loop tiling to boost the performance. gpu - fv is about 12 times faster than the cpu version, and 50 \ % faster than a non - optimized gpu implementation. for standard video input ( 320 * 240 ), gpu - fv can process each frame within 34ms on a model gpu. our experiments show that gpu - fv obtains a similar recognition accuracy as traditional fv on voc 2007 and caltech 256 image sets. we also applied gpu - fv for realtime video monitoring tasks and found that gpu - fv outperforms a number of previous works. especially, when the number of training examples are small, gpu - fv outperforms the recent popular deep cnn features borrowed from imagenet. the code can be downloaded from the following link https : / / bitbucket. org / mawenjing / gpu - fv.
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arxiv:1604.03498
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the high - temperature susceptibility of the $ q $ - state potts model behaves as $ \ gamma | t - t _ c | ^ { - \ gamma } $ as $ t \ to t _ c + $, while for $ t \ to t _ c - $ one may define both longitudinal and transverse susceptibilities, with the same power law but different amplitudes $ \ gamma _ l $ and $ \ gamma _ t $. we extend a previous analytic calculation of the universal ratio $ \ gamma / \ gamma _ l $ in two dimensions to the low - temperature ratio $ \ gamma _ t / \ gamma _ l $, and test both predictions with monte carlo simulations for $ q = 3 $ and 4. the data for $ q = 4 $ are inconclusive owing to large corrections to scaling, while for $ q = 3 $ they appear consistent with the prediction for $ \ gamma _ t / \ gamma _ l $, but not with that for $ \ gamma / \ gamma _ l $. a simple extrapolation of our analytic results to $ q \ to1 $ indicates a similar discrepancy with the corresponding measured quantities in percolation. we point out that stronger assumptions were made in the derivation of the ratio $ \ gamma / \ gamma _ l $, and our work suggests that these may be unjustified.
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arxiv:cond-mat/9908453
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we compute the $ \ mathbb { g } w ^ { r } $ - spectrum of grassmannians over fields of characteristic zero. we also compute the stabilized $ \ mathbb { l } $ - theory spectrum of grassmannians. we observe, via base - change for exceptional collections, that our computations are valid for grassmannians over commutative rings containing a field of characteristic zero. along the way, some combinatorial identities involving littlewood - richardson coefficients are established, which might be of independent interest.
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arxiv:2504.03969
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using the feynman - kac formula, a work fluctuation theorem for a brownian particle in a nonconfining potential, e. g., a potential well with finite depth, is derived. the theorem yields aninequality that puts a lower bound on the average work needed to change the potential in time. in comparison to the jarzynski equality, which holds for confining potentials, an additional termdescribing a form of energy related to the never ending diffusive expansion appears.
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arxiv:2101.03568
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we give a new computer - assisted proof of the classification of maximal subgroups of the simple group $ { } ^ 2e _ 6 ( 2 ) $ and its extensions by any subgroup of the outer automorphism group $ s _ 3 $. this is not a new result, but no earlier proof exists in the literature. a large part of the proof consists of a computational analysis of subgroups generated by an element of order 2 and an element of order 3. this method can be effectively automated, and via statistical analysis also provides a sanity check on results that may have been obtained by delicate theoretical arguments.
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arxiv:1801.08374
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given a directed graph $ g $, a transitive reduction $ g ^ t $ of $ g $ ( first studied by aho, garey, ullman [ sicomp ` 72 ] ) is a minimal subgraph of $ g $ that preserves the reachability relation between every two vertices in $ g $. in this paper, we study the computational complexity of transitive reduction in the dynamic setting. we obtain the first fully dynamic algorithms for maintaining a transitive reduction of a general directed graph undergoing updates such as edge insertions or deletions. our first algorithm achieves $ o ( m + n \ log n ) $ amortized update time, which is near - optimal for sparse directed graphs, and can even support extended update operations such as inserting a set of edges all incident to the same vertex, or deleting an arbitrary set of edges. our second algorithm relies on fast matrix multiplication and achieves $ o ( m + n ^ { 1. 585 } ) $ \ emph { worst - case } update time.
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arxiv:2504.18161
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item response theory ( irt ) aims to assess latent abilities of respondents based on the correctness of their answers in aptitude test items with different difficulty levels. in this paper, we propose the $ \ beta ^ 3 $ - irt model, which models continuous responses and can generate a much enriched family of item characteristic curve ( icc ). in experiments we applied the proposed model to data from an online exam platform, and show our model outperforms a more standard 2pl - nd model on all datasets. furthermore, we show how to apply $ \ beta ^ 3 $ - irt to assess the ability of machine learning classifiers. this novel application results in a new metric for evaluating the quality of the classifier ' s probability estimates, based on the inferred difficulty and discrimination of data instances.
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arxiv:1903.04016
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despite major advances in artificial intelligence ( ai ) for medicine and healthcare, the deployment and adoption of ai technologies remain limited in real - world clinical practice. in recent years, concerns have been raised about the technical, clinical, ethical and legal risks associated with medical ai. to increase real world adoption, it is essential that medical ai tools are trusted and accepted by patients, clinicians, health organisations and authorities. this work describes the future - ai guideline as the first international consensus framework for guiding the development and deployment of trustworthy ai tools in healthcare. the future - ai consortium was founded in 2021 and currently comprises 118 inter - disciplinary experts from 51 countries representing all continents, including ai scientists, clinicians, ethicists, and social scientists. over a two - year period, the consortium defined guiding principles and best practices for trustworthy ai through an iterative process comprising an in - depth literature review, a modified delphi survey, and online consensus meetings. the future - ai framework was established based on 6 guiding principles for trustworthy ai in healthcare, i. e. fairness, universality, traceability, usability, robustness and explainability. through consensus, a set of 28 best practices were defined, addressing technical, clinical, legal and socio - ethical dimensions. the recommendations cover the entire lifecycle of medical ai, from design, development and validation to regulation, deployment, and monitoring. future - ai is a risk - informed, assumption - free guideline which provides a structured approach for constructing medical ai tools that will be trusted, deployed and adopted in real - world practice. researchers are encouraged to take the recommendations into account in proof - of - concept stages to facilitate future translation towards clinical practice of medical ai.
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arxiv:2309.12325
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causal inference is at the heart of empirical research in natural and social sciences and is critical for scientific discovery and informed decision making. the gold standard in causal inference is performing randomized controlled trials ; unfortunately these are not always feasible due to ethical, legal, or cost constraints. as an alternative, methodologies for causal inference from observational data have been developed in statistical studies and social sciences. however, existing methods critically rely on restrictive assumptions such as the study population consisting of homogeneous elements that can be represented in a single flat table, where each row is referred to as a unit. in contrast, in many real - world settings, the study domain naturally consists of heterogeneous elements with complex relational structure, where the data is naturally represented in multiple related tables. in this paper, we present a formal framework for causal inference from such relational data. we propose a declarative language called carl for capturing causal background knowledge and assumptions and specifying causal queries using simple datalog - like rules. carl provides a foundation for inferring causality and reasoning about the effect of complex interventions in relational domains. we present an extensive experimental evaluation on real relational data to illustrate the applicability of carl in social sciences and healthcare.
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arxiv:2004.03644
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the sars - cov - 2 pandemic has caused significant mortality and morbidity worldwide, sparing almost no community. as the disease will likely remain a threat for years to come, an understanding of the precise influences of human demographics and settlement, as well as the dynamic factors of climate, susceptible depletion, and intervention, on the spread of localized epidemics will be vital for mounting an effective response. we consider the entire set of local epidemics in the united states ; a broad selection of demographic, population density, and climate factors ; and local mobility data, tracking social distancing interventions, to determine the key factors driving the spread and containment of the virus. assuming first a linear model for the rate of exponential growth ( or decay ) in cases / mortality, we find that population - weighted density, humidity, and median age dominate the dynamics of growth and decline, once interventions are accounted for. a focus on distinct metropolitan areas suggests that some locales benefited from the timing of a nearly simultaneous nationwide shutdown, and / or the regional climate conditions in mid - march ; while others suffered significant outbreaks prior to intervention. using a first - principles model of the infection spread, we then develop predictions for the impact of the relaxation of social distancing and local climate conditions. a few regions, where a significant fraction of the population was infected, show evidence that the epidemic has partially resolved via depletion of the susceptible population ( i. e., " herd immunity " ), while most regions in the united states remain overwhelmingly susceptible. these results will be important for optimal management of intervention strategies, which can be facilitated using our online dashboard.
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arxiv:2007.00159
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\ tau $ and $ z \ rightarrow \ mu \ mu $ cross - sections has been measured to be 1. 09 $ \ pm $ 0. 17, consistent with lepton universality. theoretical predictions, calculated at next - to - next - to - leading order ( nnlo ) in qcd using recent parton distribution functions, are found to be in agreement with the measurements.
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arxiv:1109.3371
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in this article we propose to simulate acoustic black holes with ions in rings. if the ions are rotating with a stationary and inhomogeneous velocity profile, regions can appear where the ion velocity exceeds the group velocity of the phonons. in these regions phonons are trapped like light in black holes, even though we have a discrete field theory and a nonlinear dispersion relation. we study the appearance of hawking radiation in this setup and propose a scheme to detect it.
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arxiv:0904.4801
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relativistic microcausality is the statement that local field operators commute outside the light - cone. this condition is known to break down in low - energy effective theories, such as $ p ( x ) $ models with a derivative interaction term of the ` ` wrong sign ". despite their lorentz - invariant form, these theories can exhibit superluminal propagation on lorentz - breaking backgrounds. we approach this phenomenon by computing the full operator - valued commutator in position space, perturbatively in interaction picture. after testing this formalism on a $ \ lambda \ phi ^ 4 $ theory, we apply it to a $ p ( x ) $ model. there, we show that the perturbative corrections to the free - theory commutator contain derivatives of delta functions with support on the standard minkowski light cone. while these corrections vanish on lorentz - invariant states, they become ` ` activated " on states where lorentz symmetry is spontaneously broken. in this case, they approximate the new ` ` sound - cone " by means of a taylor expansion. by applying linear response theory to an extended source, we show that deviations from standard causality are already present at first order in this expansion. finally, we try to understand what goes wrong with the standard argument according to which lorentz invariance implies microcausality.
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arxiv:2504.16992
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we study center - of - mass oscillations of a dipolar bose - einstein condensate in the vicinity of a superconducting surface. we show that the magnetic field of the magnetic dipoles induces eddy currents in the superconductor, which act back on the bose - einstein condensate. this leads to a shift of its oscillation frequency and to an anharmonic coupling of the bose - einstein condensate with the superconductor. the anharmonicity creates a coupling to one of the collective modes of the condensate that can be resonantly enhanced, if the parameters of the condensate are chosen properly. this provides a new physical mechanism to couple a bose - einstein condensate and a superconductor which becomes significant for 52cr, 168er or 164dy condensates in superconducting mircotraps.
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arxiv:1306.4086
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when combining apparently inconsistent experimental results, one often implements errors on errors. the particle data group ' s phenomenological prescription offers a practical solution but lacks a firm theoretical foundation. to address this, d ' agostini and cowan have proposed bayesian and frequentist approaches, respectively, both introducing gamma - distributed auxiliary variables to model uncertainty in quoted errors. in this letter, we show that these two formulations admit a parameter - by - parameter correspondence, and are structurally equivalent. this identification clarifies how bayesian prior choices can be interpreted in terms of frequentist sampling assumptions, providing a unified probabilistic framework for modeling uncertainty in quoted variances.
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arxiv:2505.06521
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in high energy physics experiment trigger systems, track segment seeding is a resource consuming function and the primary reason is the computing complexity of the segment finding process. as the moore ' s law is reaching its physical limit, reducing computing complexity should be carefully considered, rather than keep piling up silicon resources. the tiny triplet finder is a scheme that reduces the computing complexity of the segment seeding. as a proof of concept, a 3d track segment seeding engine core based on the tiny triplet finder has been implemented and tested in a low - cost fpga device. the seeding engine is designed to preselect and group hits ( stubs ) from detector layers to feed subsequent track fitting stage. the seeding engine consists of a hough transform space for r - z view and a tiny triplet finder for r - phi view to implement 3d constraints. the seeding engine is organized as a pipeline so that each hit is processed in a single clock cycle. taking advantage of the register - like storage block scheme which enables effectively resetting of a block ram within a single clock cycle, clearing or refreshing the seeding engine takes only one clock cycles between two events. the tiny triplet finder is also a generic coincidence finding scheme that can be used for many tasks. as a versatility demonstration, track segment finding performances for two distinctive detector geometries are tested in our seeding engine. in a collider barrel - layer geometry, the fake segment rates are studied for 3d ( i. e., both r - phi and r - z views ) and 2d ( i. e., r - phi or r - z view only ) configurations for high hit multiplicity events ( > 4000 hits / layer in the barrel region ). another detector geometry contains strip plane layers with timing information. the numbers of coincidences, both real or fake, with or without timing ( " 3d " or " 2d " ) information at various hit multiplicities are studied.
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arxiv:2305.09834
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the automaton constrained tree knapsack problem is a variant of the knapsack problem in which the items are associated with the vertices of the tree, and we can select a subset of items that is accepted by a top - down tree automaton. if the capacities or the profits of items are integers, the problem can be solved in pseudo - polynomial time using the dynamic programming algorithm. however, the natural implementation of this algorithm has a quadratic pseudo - polynomial factor in its complexity because of the max - plus convolution. in this study, we propose a new dynamic programming technique, called \ emph { heavy - light recursive dynamic programming }, to obtain pseudo - polynomial time algorithms having linear pseudo - polynomial factors in the complexity. such algorithms can be used for solving the problems with polynomially small capacities / profits efficiently, and used for deriving efficient fully polynomial - time approximation schemes. we also consider the $ k $ - subtree version problem that finds $ k $ disjoint subtrees and a solution in each subtree that maximizes total profit under a budget constraint. we show that this problem can be solved in almost the same order as the original problem.
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arxiv:1807.04942
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constraint automata ( ca ) constitute a coordination model based on finite automata on infinite words. originally introduced for modeling of coordinators, an interesting new application of cas is implementing coordinators ( i. e., compiling cas into executable code ). such an approach guarantees correctness - by - construction and can even yield code that outperforms hand - crafted code. the extent to which these two potential advantages materialize depends on the smartness of ca - compilers and the existence of proofs of their correctness. every transition in a ca is labeled by a " data constraint " that specifies an atomic data - flow between coordinated processes as a first - order formula. at run - time, compiler - generated code must handle data constraints as efficiently as possible. in this paper, we present, and prove the correctness of two optimization techniques for ca - compilers related to handling of data constraints : a reduction to eliminate redundant variables and a translation from ( declarative ) data constraints to ( imperative ) data commands expressed in a small sequential language. through experiments, we show that these optimization techniques can have a positive impact on performance of generated executable code.
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arxiv:1608.04592
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this paper introduces the event capture annotation tool ( ecat ), a user - friendly, open - source interface tool for annotating events and their participants in video, capable of extracting the 3d positions and orientations of objects in video captured by microsoft ' s kinect ( r ) hardware. the modeling language voxml ( pustejovsky and krishnaswamy, 2016 ) underlies ecat ' s object, program, and attribute representations, although ecat uses its own spec for explicit labeling of motion instances. the demonstration will show the tool ' s workflow and the options available for capturing event - participant relations and browsing visual data. mapping ecat ' s output to voxml will also be addressed.
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arxiv:1610.01247
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it is shown that the fidelity, a basic notion of quantum information science, may be used to characterize quantum phase transitions, regardless of what type of internal order is present in quantum many - body states. if the fidelity of two given states vanishes, then there are two cases : ( 1 ) they are in the same phase if the distinguishability results from irrelevant local information ; or ( 2 ) they are in different phases if the distinguishability results from relevant long - distance information. the different effects of irrelevant and relevant information are quantified, which allows us to identify unstable and stable fixed points ( in the sense of renormalization group theory ). a physical implication of our results is the occurrence of the orthogonality catastrophe near the transition points.
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arxiv:cond-mat/0701608
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we present a perturbative qcd factorization formalism for the production of heavy quarkonia of large transverse momentum $ p _ t $ at collider energies, which includes both the leading power ( lp ) and next - to - leading power ( nlp ) contributions to the cross section in the $ m _ q ^ 2 / p _ t ^ 2 $ expansion for heavy quark mass $ m _ q $. we estimate fragmentation functions in the non - relativistic qcd formalism, and reproduce the bulk of the large enhancement found in explicit nlo calculations in the color singlet model. heavy quarkonia produced from nlp channels prefer longitudinal polarization.
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arxiv:1109.1520
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we extend a previously developed model for the stark resonances of the water molecule. the method employs a partial - wave expansion of the single - particle orbitals using spherical harmonics. to find the resonance positions and decay rates, we use the exterior complex scaling approach which involves the analytic continuation of the radial variable into the complex plane and yields a non - hermitian hamiltonian matrix. the real part of the eigenvalues provides the resonance positions ( and thus the stark shifts ), while the imaginary parts $ - \ gamma / 2 $ are related to the decay rates $ \ gamma $, i. e., the full - widths at half - maximum of the breit - wigner resonances. we focus on the three outermost ( valence ) orbitals, as they are dominating the ionization process. we find that for forces directed in the three cartesian co - ordinates, the fastest ionizing orbital always displays a non - monotonic stark shift. for the case of fields along the molecular axis we also compare results as a function of the number of spherical harmonics included ( $ \ ell _ { \ max } = 3, 4 $ ). we also compare our results to the total molecular stark shifts for the hartree - fock and coupled cluster methods.
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arxiv:2203.10401
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vortex fiber nulling is a method for spectroscopically characterizing exoplanets at small angular separations, $ \ lesssim \ lambda / d $, from their host star. the starlight is suppressed by creating an optical vortex in the system point spread function, which prevents the stellar field from coupling into the fundamental mode of a single - mode optical fiber. light from the planet, on the other hand, couples into the fiber and is routed to a spectrograph. using a prototype vortex fiber nuller ( vfn ) designed for monochromatic light, we demonstrate coupling fractions of $ 6 \ times10 ^ { - 5 } $ and $ > 0. 1 $ for the star and planet, respectively.
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arxiv:1811.02083
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the digital age, driven by the ai revolution, brings significant opportunities but also conceals security threats, which we refer to as cyber shadows. these threats pose risks at individual, organizational, and societal levels. this paper examines the systemic impact of these cyber threats and proposes a comprehensive cybersecurity strategy that integrates ai - driven solutions, such as intrusion detection systems ( ids ), with targeted policy interventions. by combining technological and regulatory measures, we create a multilevel defense capable of addressing both direct threats and indirect negative externalities. we emphasize that the synergy between ai - driven solutions and policy interventions is essential for neutralizing cyber threats and mitigating their negative impact on the digital economy. finally, we underscore the need for continuous adaptation of these strategies, especially in response to the rapid advancement of autonomous ai - driven attacks, to ensure the creation of secure and resilient digital ecosystems.
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arxiv:2501.09025
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manganese ( mn ) abundances are sensitive probes of the progenitors of type ia supernovae ( sne ). in this work, we present a catalog of manganese abundances in dwarf spheroidal satellites of the milky way, measured using medium - resolution spectroscopy. using a simple chemical evolution model, we infer the manganese yield of type ia sne in the sculptor dwarf spheroidal galaxy ( dsph ) and compare to theoretical yields. the sub - solar yield from type ia sne ( $ \ mathrm { [ mn / fe ] } _ { \ mathrm { ia } } = - 0. 30 _ { - 0. 03 } ^ { + 0. 03 } $ at $ \ mathrm { [ fe / h ] } = - 1. 5 $ dex, with negligible dependence on metallicity ) implies that sub - chandrasekhar - mass ( sub - $ m _ { \ mathrm { ch } } $ ) white dwarf progenitors are the dominant channel of type ia sne at early times in this galaxy, although some fraction ( $ \ gtrsim20 \ % $ ) of $ m _ { \ mathrm { ch } } $ type ia or type iax sne are still needed to produce the observed yield. however, this result does not hold in all environments. in particular, we find that dsph galaxies with extended star formation histories ( leo i, fornax dsphs ) appear to have higher [ mn / fe ] at a given metallicity than galaxies with early bursts of star formation ( sculptor dsph ), suggesting that $ m _ { \ mathrm { ch } } $ progenitors may become the dominant channel of type ia sne at later times in a galaxy ' s chemical evolution.
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arxiv:2001.01716
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we consider the model of the focusing one - dimensional nonlinear schr \ " odinger equation ( fnlse ) in the presence of an unstable constant background, which exhibits coherent solitary wave structures - - breathers. within the inverse scattering transform ( ist ) method, we study the problem of the scattering data numerical computation for a broad class of breathers localized in space. such direct scattering transform ( dst ) procedure requires a numerical solution of the auxiliary zakharov - - shabat system with boundary conditions corresponding to the background. to find the solution we compute the transfer matrix using the second - order boffetta - - osborne approach and recently developed high - order numerical schemes based on the magnus expansion. to recover the scattering data of breathers, we derive analytical relations between the scattering coefficients and the transfer matrix elements. then we construct localized single - and multi - breather solutions and verify the developed numerical approach by accurately recovering the complete set of the scattering data, which provides us with information about the amplitude, velocity, phase, and position of each breather. to combine the conventional ist approach with the efficient dressing method for multi - breather solutions, we provide the exact relation between the parameters of breathers in these two frameworks.
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arxiv:2308.04568
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the classical wiener - khinchin theorem ( wkt ), which can extract spectral information by classical interferometers through fourier transform, is a fundamental theorem used in many disciplines. however, there is still need for a quantum version of wkt, which could connect correlated biphoton spectral information by quantum interferometers. here, we extend the classical wkt to its quantum counterpart, i. e., extended wkt ( e - wkt ), which is based on two - photon quantum interferometry. according to the e - wkt, the difference - frequency distribution of the biphoton wavefunctions can be extracted by applying a fourier transform on the time - domain hong - ou - mandel interference ( homi ) patterns, while the sum - frequency distribution can be extracted by applying a fourier transform on the time - domain noon state interference ( nooni ) patterns. we also experimentally verified the wkt and e - wkt in a mach - zehnder interference ( mzi ), a homi and a nooni. this theorem can be directly applied to quantum spectroscopy, where the spectral correlation information of biphotons can be obtained from time - domain quantum interferences by fourier transform. this may open a new pathway for the study of light - matter interaction at the single photon level.
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arxiv:1709.04837
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the various mechanisms of magneto - convective energy transport determines the structure of sunspots and active regions. we characterise the appearance of light bridges and other fine - structure details and elaborate on their magneto - convective nature. we present speckle - reconstructed images taken with the broad - band imager at the 1. 5 m gregor telescope in the 486nm and 589nm bands. we estimate the spatial resolution from the noise characteristics of the image bursts and obtain 0. 08 " at 589nm. we describe structure details in individual best images as well as the temporal evolution of selected features. we find branched dark lanes extending along thin ( ~ 1 " ) light bridges in sunspots at various heliocentric angles. in thick ( ~ 2 " ) light bridges the branches are disconnected from the central lane and have a y shape with a bright grain toward the umbra. the images reveal that light bridges exist on varying intensity levels and that their small - scale features evolve on timescales of minutes. faint light bridges show dark lanes outlined by the surrounding bright features. dark lanes are very common and are also found in the boundary of pores. they have a characteristic width of 0. 1 " or smaller. intergranular dark lanes of that width are seen in active region granulation. while central dark lanes in thin light bridges are elevated and associated with an density increase above upflows, the dark lane branches correspond to locations of downflows and are depressed relative to the adjacent bright plasma. thick light bridges with central dark lanes show no projection effect. they have a flat elevated plateau that falls off steeply at the umbral boundary. there, y - shaped filaments form as they do in the inner penumbra. this indicates the presence of inclined magnetic fields, meaning that the umbral magnetic field is wrapped around the convective light bridge.
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arxiv:1607.07094
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open source software ( oss ) development relies on diverse skill sets. however, to our knowledge, there are no tools which detect oss - related skills. in this paper, we present a novel method to detect oss skills and prototype it in a tool called disko. our approach relies on identifying relevant signals, which are measurable activities or cues associated with a skill. our tool detects how contributors 1 ) teach others to be involved in oss projects, 2 ) show commitment towards an oss project, 3 ) have knowledge in specific programming languages, and 4 ) are familiar with oss practices. we then evaluate the tool by administering a survey to 455 oss contributors. we demonstrate that disko yields promising results : it detects the presence of these skills with precision scores between 77 % to 97 %. we also find that over 54 % of participants would display their high - proficiency skills. our approach can be used to transform existing oss experiences, such as identifying collaborators, matching mentors to mentees, and assigning project roles. given the positive results and potential impact of our approach, we outline future research opportunities in interpreting and sharing oss skills.
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arxiv:2203.02027
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context. interstellar scintillation ( iss ) of pulsar emission can be used both as a probe of the ionised interstellar medium ( iism ) and cause corruptions in pulsar timing experiments. of particular interest are so - called scintillation arcs which can be used to measure time - variable interstellar scattering delays directly, potentially allowing high - precision improvements to timing precision. aims. the primary aim of this study is to carry out the first sizeable and self - consistent census of diffractive pulsar scintillation and scintillation - arc detectability at low frequencies, as a primer for larger - scale iism studies and pulsar - timing related propagation studies with the low - frequency array ( lofar ) high band antennae ( hba ). results. in this initial set of 31 sources, 15 allow full determination of the scintillation properties ; nine of these show detectable scintillation arcs at 120 - 180 mhz. eight of the observed sources show unresolved scintillation ; and the final eight don ' t display diffractive scintillation. some correlation between scintillation detectability and pulsar brightness and dispersion measure is apparent, although no clear cut - off values can be determined. our measurements across a large fractional bandwidth allow a meaningful test of the frequency scaling of scintillation parameters, uncorrupted by influences from refractive scintillation variations. conclusions. our results indicate the powerful advantage and great potential of iss studies at low frequencies and the complex dependence of scintillation detectability on parameters like pulsar brightness and interstellar dispersion. this work provides the first installment of a larger - scale census and longer - term monitoring of interstellar scintillation effects at low frequencies.
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arxiv:2203.10409
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we consider a system of reaction - diffusion equations including chemotaxis terms and coming out of the modeling of multiple sclerosis. the global existence of strong solutions to this system in any dimension is proved, and it is also shown that the solution is bounded uniformly in time. finally, a nonlinear stability result is obtained when the chemotaxis term is not too big. we also perform numerical simulations to show the appearance of turing patterns when the chemotaxis term is large.
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arxiv:2009.13131
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unmanned aerial vehicles ( uavs ) have moved beyond a platform for hobbyists to enable environmental monitoring, journalism, film industry, search and rescue, package delivery, and entertainment. this paper describes 3d displays using swarms of flying light specks, flss. an fls is a small ( hundreds of micrometers in size ) uav with one or more light sources to generate different colors and textures with adjustable brightness. a synchronized swarm of flss renders an illumination in a pre - specified 3d volume, an fls display. an fls display provides true depth, enabling a user to perceive a scene more completely by analyzing its illumination from different angles. an fls display may either be non - immersive or immersive. both will support 3d acoustics. non - immersive fls displays may be the size of a 1980 ' s computer monitor, enabling a surgical team to observe and control micro robots performing heart surgery inside a patient ' s body. immersive fls displays may be the size of a room, enabling users to interact with objects, e. g., a rock, a teapot. an object with behavior will be constructed using fls - matters. fls - matter will enable a user to touch and manipulate an object, e. g., a user may pick up a teapot or throw a rock. an immersive and interactive fls display will approximate star trek ' s holodeck. a successful realization of the research ideas presented in this paper will provide fundamental insights into implementing a holodeck using swarms of flss. a holodeck will transform the future of human communication and perception, and how we interact with information and data. it will revolutionize the future of how we work, learn, play and entertain, receive medical care, and socialize.
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arxiv:2111.03657
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in this paper we present an improved ri - type prescription appropriate for the non - perturbative renormalization of gauge invariant nonlocal operators. in this prescription, the non - perturbative vertex function is improved by subtracting unwanted finite lattice spacing ( $ a $ ) effects, calculated in lattice perturbation theory. the method is versatile and can be applied to a wide range of fermion and gluon actions, as well as types of nonlocal operators. the presence of operator mixing can also be accommodated. compared to the standard ri ' prescription, this variant can be recast as a supplementary finite renormalization, whose coefficients bring about corrections of higher order in $ a $ ; consequently, it coincides with standard ri ' as $ a \ to 0 $, however it can afford us a smoother and more controlled extrapolation to the continuum limit. in this proof - of - concept calculation we focus on nonlocal fermion bilinear operators containing a straight wilson line. in the numerical implementation we use wilson / clover fermions and iwasaki improved gluons. the finite - $ a $ terms were calculated to one - loop level in lattice perturbation theory, and to all orders in $ a $, using the same action as the non - perturbative vertex functions. we find that the method leads to significant improvement in the perturbative region indicated by small and intermediate values of the length of the wilson line. this results in a robust extraction of the renormalization functions in that region. we have also applied the above method to operators with stout - smeared links. we show how to perform the perturbative correction for any number of smearing iterations, and evaluate its effect on the power divergent renormalization coefficients.
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arxiv:2207.09977
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we present the results of a numerical study of the fluid $ f $, $ p $ and the gravitational $ w $ modes for increasingly relativistic nonrotating polytropes. the results for $ f $ and $ w $ - modes are in good agreement with previous data for uniform density stars, which supports an understanding of the nature of the gravitational wave modes based on the uniform density data. we show that the $ p $ - modes can become extremely long - lived for some relativistic stars. this effect is attributed to the change in the perturbed density distribution as the star becomes more compact.
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arxiv:gr-qc/9706010
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the hausdorff distance is a fundamental measure for comparing sets of vectors, widely used in database theory and geometric algorithms. however, its exact computation is computationally expensive, often making it impractical for large - scale applications such as multi - vector databases. in this paper, we introduce an approximation framework that efficiently estimates the hausdorff distance while maintaining rigorous error bounds. our approach leverages approximate nearest - neighbor ( ann ) search to construct a surrogate function that preserves essential geometric properties while significantly reducing computational complexity. we provide a formal analysis of approximation accuracy, deriving both worst - case and expected error bounds. additionally, we establish theoretical guarantees on the stability of our method under transformations, including translation, rotation, and scaling, and quantify the impact of non - uniform scaling on approximation quality. this work provides a principled foundation for integrating hausdorff distance approximations into large - scale data retrieval and similarity search applications, ensuring both computational efficiency and theoretical correctness.
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arxiv:2503.06833
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the absence of a physically motivated model for large scale profiles of cosmic voids limits our ability to extract valuable cosmological information from their study. in this paper, we address this problem by introducing the spherically compensated cosmic regions, named cospheres. such cosmic regions are identified around local extrema in the density field and admit a unique compensation radius $ r _ 1 $ where the internal spherical mass is exactly compensated. their origin is studied by extending the standard peak model and implementing the compensation condition. since the compensation radius evolves as the universe itself, $ r _ 1 ( t ) \ propto a ( t ) $, cospheres behave as bubble universes with fixed comoving volume. using the spherical collapse model, we reconstruct their profiles with a very high accuracy until $ z = 0 $ in n - body simulations. cospheres are symmetrically defined and reconstructed for both central maximum ( seeding haloes and galaxies ) and minimum ( identified with cosmic voids ). we show that the full non linear dynamics can be solved analytically around this particular compensation radius, providing useful predictions for cosmology. this formalism highlights original correlations between local extremum and their large scale cosmic environment. the statistical properties of these spherically compensated cosmic regions and the possibilities to constrain efficiently both cosmology and gravity will be investigated in companion papers.
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arxiv:1709.04490
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in this work, we present an opto - electro - mechanical modulator ( oemm ) for rf - to - optical transduction realized via an ultra - coherent nanomembrane resonator capacitively coupled to an rf injection circuit made of a microfabricated read - out able to improve the electro - optomechanical interaction. this device configuration can be embedded in a fabry - perot cavity for electromagnetic cooling of the lc circuit in a dilution refrigerator exploiting the opto - electro - mechanical interaction. to this aim, an optically measured steady - state frequency shift of 380 hz was seen with a polarization voltage of 30 v and a $ q $ - factor of the assembled device above $ 10 ^ 6 $ at room temperature. the rf - sputtered titanium nitride layer can be made superconductive to develop efficient quantum ~ transducers.
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arxiv:2307.13049
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during the past few years, advances in mobile communication theory have enabled the development and deployment of different wireless technologies, complementary to each other. hence, their integration can realize a unified wireless system that has the best features of the individual networks. next - generation wireless systems ( ngws ) integrate different wireless systems, each of which is optimized for some specific services and coverage area to provide ubiquitous communications to the mobile users. in this paper, we propose to enhance the handoff performance of mobile ip in wireless ip networks by reducing the false handoff probability in the ngws handoff management protocol. based on the information of false handoff probability, we analyze its effect on mobile speed and handoff signaling delay.
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arxiv:1006.3376
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we study collinear relative equilibria of the planar four - vortex problem where three of the four vortex strengths are identical. the $ s _ 3 $ invariance obtained from the equality of vorticities is used to reduce the defining equations and organize the solutions into two distinct groups based on the ordering of the vortices along the line. the number and type of solutions are given, along with a discussion of the bifurcations that occur. the linear stability of all solutions is investigated rigorously and stable solutions are found to exist for cases where the vorticities have mixed signs. we employ a combination of analysis and computational algebraic geometry to prove our results.
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arxiv:1704.08647
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we present an analysis of high - resolution imaging of an exoplanet by a meter - class telescope positioned at a real image of the exoplanet created by the solar gravity lens. we assume an exoplanet viewed in full phase and a simple deconvolution method to correct for the intrinsic blur caused by aberrations in the solar gravity lens, and account for the foreground light of the solar corona. we derive equations for the measurement times required for the telescope to produce such a high - resolution image, and find that due to shot noise considerations these times are large compared to human lifespans. we also discuss how measurement times could potentially be significantly shorter for exoplanets with special orbital and rotational parameters.
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arxiv:2004.12907
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large vision - language models ( vlms ) like clip have demonstrated good zero - shot learning performance in the unsupervised domain adaptation task. yet, most transfer approaches for vlms focus on either the language or visual branches, overlooking the nuanced interplay between both modalities. in this work, we introduce a unified modality separation ( unimos ) framework for unsupervised domain adaptation. leveraging insights from modality gap studies, we craft a nimble modality separation network that distinctly disentangles clip ' s features into language - associated and vision - associated components. our proposed modality - ensemble training ( met ) method fosters the exchange of modality - agnostic information while maintaining modality - specific nuances. we align features across domains using a modality discriminator. comprehensive evaluations on three benchmarks reveal our approach sets a new state - of - the - art with minimal computational costs. code : https : / / github. com / tl - uestc / unimos
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arxiv:2403.06946
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we introduce a variant of the proximal gradient method in which the quadratic term is diagonal but may be indefinite, and is safeguarded by a trust region. our method is a special case of the proximal quasi - newton trust - region method of arxiv : 2103. 15993v3. we provide closed - form solution of the step computation in certain cases where the nonsmooth term is separable and the trust region is defined in infinity norm, so that no iterative subproblem solver is required. our analysis expands upon that of arxiv : 2103. 15993v3 by generalizing the trust - region approach to problems with bound constraints. we provide an efficient open - source implementation of our method, named trdh, in the julia language in which hessians approximations are given by diagonal quasi - newton updates. trdh evaluates one standard proximal operator and one indefinite proximal operator per iteration. we also analyze and implement a variant named itrdh that performs a single indefinite proximal operator evaluation per iteration. we establish that itrdh enjoys the same asymptotic worst - case iteration complexity as trdh. we report numerical experience on unconstrained and bound - constrained problems, where trdh and itrdh are used both as standalone and subproblem solvers. our results illustrate that, as standalone solvers, trdh and itrdh improve upon the quadratic regularization method r2 of arxiv : 2103. 15993v3 but also sometimes upon their quasi - newton trust - region method, referred to here as tr - r2, in terms of smooth objective value and gradient evaluations. on challenging nonnegative matrix factorization, binary classification and data fitting problems, trdh and itrdh used as subproblem solvers inside tr improve upon tr - r2 for at least one choice of diagonal approximation.
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arxiv:2309.08433
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source code diffs are used on a daily basis as part of code review, inspection, and auditing. to facilitate understanding, they are typically accompanied by explanations that describe the essence of what is changed in the program. as manually crafting high - quality explanations is a cumbersome task, researchers have proposed automatic techniques to generate code diff explanations. existing explanation generation methods solely focus on static analysis, i. e., they do not take advantage of runtime information to explain code changes. in this paper, we propose collector - sahab, a novel tool that augments code diffs with runtime difference information. collector - sahab compares the program states of the original ( old ) and patched ( new ) versions of a program to find unique variable values. then, collector - sahab adds this novel runtime information to the source code diff as shown, for instance, in code reviewing systems. as an evaluation, we run collector - sahab on 584 code diffs for defects4j bugs and find it successfully augments the code diff for 95 % ( 555 / 584 ) of them. we also perform a user study and ask eight participants to score the augmented code diffs generated by collector - sahab. per this user study, we conclude that developers find the idea of adding runtime data to code diffs promising and useful. overall, our experiments show the effectiveness and usefulness of collector - sahab in augmenting code diffs with runtime difference information. publicly - available repository : https : / / github. com / assert - kth / collector - sahab.
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arxiv:2212.11077
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we combine the principle of gauge invariance with extrinsic string geometry to develop a lattice model that can be employed to theoretically describe properties of chiral, unbranched homopolymers. we find that in its low temperature phase the model is in the same universality class with proteins that are deposited in the protein data bank, in the sense of the compactness index. we apply the model to analyze various statistical aspects of folded proteins. curiously we find that it can produce results that are a very good good match to the data in the protein data bank.
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arxiv:0902.2920
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we obtain a pair of nontrivial solutions for a class of concave - linear - convex type elliptic problems that are either critical or subcritical. the solutions we find are neither local minimizers nor of mountain pass type in general. they are higher critical points in the sense that they each have a higher critical group that is nontrivial. this fact is crucial for showing that our solutions are nontrivial. we also prove some intermediate results of independent interest on the localization and homotopy invariance of critical groups of functionals involving critical sobolev exponents.
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arxiv:1912.05648
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in this paper we define and study a new family of graphs that generalises the notions of line graphs and path graphs. let $ g $ be a graph with no loops but possibly with parallel edges. an \ emph { $ \ ell $ - link } of $ g $ is a walk of $ g $ of length $ \ ell \ geqslant 0 $ in which consecutive edges are different. we identify an $ \ ell $ - link with its reverse sequence. the \ emph { $ \ ell $ - link graph $ \ mathbb { l } _ \ ell ( g ) $ } of $ g $ is the graph with vertices the $ \ ell $ - links of $ g $, such that two vertices are joined by $ \ mu \ geqslant 0 $ edges in $ \ mathbb { l } _ \ ell ( g ) $ if they correspond to two subsequences of each of $ \ mu $ $ ( \ ell + 1 ) $ - links of $ g $. by revealing a recursive structure, we bound from above the chromatic number of $ \ ell $ - link graphs. as a corollary, for a given graph $ g $ and large enough $ \ ell $, $ \ mathbb { l } _ \ ell ( g ) $ is $ 3 $ - colourable. by investigating the shunting of $ \ ell $ - links in $ g $, we show that the hadwiger number of a nonempty $ \ mathbb { l } _ \ ell ( g ) $ is greater or equal to that of $ g $. hadwiger ' s conjecture states that the hadwiger number of a graph is at least the chromatic number of that graph. the conjecture has been proved by reed and seymour ( 2004 ) for line graphs, and hence $ 1 $ - link graphs. we prove the conjecture for a wide class of $ \ ell $ - link graphs.
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arxiv:1402.7235
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we present an explicit algorithm for tessellating the algebraic surfaces ( real 4 - manifolds ) f ( n ) embedded in cp3 defined by the equation z0 ^ n + z1 ^ n + z2 ^ n + z3 ^ n = 0 in the standard homogeneous coordinates [ z0, z1, z2, z3 ], where n is any positive integer. note that f ( 4 ) in particular is a k3 surface. our tessellation contains a minimal number of vertices, namely the n - th roots of unity in the six standard projective lines cp1 in cp3, which form an obvious framework for constructing a natural tessellation of f ( n ). our tessellation is invariant under the action of the obvious isomorphism group of f ( n ) induced by permutations and phase multiplications of the coordinates, and the action is transitive on the set of 4 - cells. the tessellation is built upon a similar triangulation for the corresponding algebraic curves in cp2.
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arxiv:0804.3218
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in this paper, we define a module of stark systems over a complete gorenstein local ring with a finite residue field of odd characteristic. under some mild assumptions, we show that it is free of rank one and that these systems control all the fitting ideals of the pontryagin dual of the dual selmer group. these results generalize the work of b. mazur and k. rubin on stark systems over a principal ideal ring.
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arxiv:1612.06531
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we discuss systematic approaches to the classification of string / m theory vacua, and physical questions this might help us resolve. to this end, we initiate the study of ensembles of effective lagrangians, which can be used to precisely study the predictive power of string theory, and in simple examples can lead to universality results. using these ideas, we outline an approach to estimating the number of vacua of string / m theory which can realize the standard model.
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arxiv:hep-th/0303194
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in one - dimensional anharmonic lattices, we construct nonlinear standing waves ( sws ) reducing to harmonic sws at small amplitude. for sws with spatial periodicity incommensurate with the lattice period, a transition by breaking of analyticity versus wave amplitude is observed. as a consequence of the discreteness, oscillatory linear instabilities, persisting for arbitrarily small amplitude in infinite lattices, appear for all wave numbers q not equal to zero or \ pi. incommensurate analytic sws with | q | > \ pi / 2 may however appear as ' quasi - stable ', as their instability growth rate is of higher order.
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arxiv:nlin/0005068
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we consider and resolve the gap problem for almost quaternion - hermitian structures, i. e. we determine the maximal and submaximal symmetry dimensions, both for lie algebras and lie groups, in the class of almost quaternion - hermitian manifolds. we classify all structures with such symmetry dimensions. geometric properties of the submaximally symmetric spaces are studied, in particular we identify locally conformally quaternion - k \ " ahler structures as well as quaternion - k \ " ahler with torsion.
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arxiv:1812.11229
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we prove existence and uniqueness of solutions to the minkowski problem in any domain of dependence $ d $ in $ ( 2 + 1 ) $ - dimensional minkowski space, provided $ d $ is contained in the future cone over a point. namely, it is possible to find a smooth convex cauchy surface with prescribed curvature function on the image of the gauss map. this is related to solutions of the monge - amp \ ` ere equation $ \ det d ^ 2 u ( z ) = ( 1 / \ psi ( z ) ) ( 1 - | z | ^ 2 ) ^ { - 2 } $ on the unit disc, with the boundary condition $ u | _ { \ partial \ mathbb { d } } = \ varphi $, for $ \ psi $ a smooth positive function and $ \ varphi $ a bounded lower semicontinuous function. we then prove that a domain of dependence $ d $ contains a convex cauchy surface with principal curvatures bounded from below by a positive constant if and only if the corresponding function $ \ varphi $ is in the zygmund class. moreover in this case the surface of constant curvature $ k $ contained in $ d $ has bounded principal curvatures, for every $ k < 0 $. in this way we get a full classification of isometric immersions of the hyperbolic plane in minkowski space with bounded shape operator in terms of zygmund functions of $ \ partial \ mathbb { d } $. finally, we prove that every domain of dependence as in the hypothesis of the minkowski problem is foliated by the surfaces of constant curvature $ k $, as $ k $ varies in $ ( - \ infty, 0 ) $.
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arxiv:1505.06748
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quantum key distribution ( qkd ) networks is expected to provide information - theoretical secured ( its ) communication over long distances. qkd networks based trusted relay architecture are now the most widely used scheme in practice. however, it is an unrealistic assumption that all relays are fully trustable in complex networks. in the past, only a few studies have theoretically analyzed the case of passive eavesdropping attack by dishonest relays and corresponding defense method. however, we have found that active attacks by dishonest relays can be more threatening. with the consideration of passive and active attacks, we treat dishonest relays as byzantine nodes and analyzes the upper limit of byzantine nodes that the qkd network can accommodate. in this paper, we propose an its byzantine - fault tolerance ( bft ) qkd network scheme to achieve end - to - end key distribution based on point - to - point qkd links. to ensure consistency and provide bft ability in the qkd network, we design an itsbft - consensus protocol for this network scheme. to ensure the information - theoretic security of consensus, we design a temporary signature scheme based on point - to - point qkd link keys. to prevent byzantine nodes from disrupting the execution process of key distribution, we design an end - to - end key distribution scheme combined with consensus. we theoretically analyze proposed itsbft - qkd network scheme from four aspects : qkd key distribution security, temporary signature security, consensus security, and leader election fairness. the simulation result proved the feasibility and demonstrate the performance.
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arxiv:2204.09832
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we studied the dynamical response of a nanomechanical resonator to biomolecular ( e. g. dna ) adsorptions on a resonator ' s surface by using a theoretical model, which considers the hamiltonian h such that the potential energy consists of elastic bending energy of a resonator and the potential energy for biomolecular interactions. it was shown that the resonant frequency shift of a resonator due to biomolecular adsorption depends on not only the mass of adsorbed biomolecules but also the biomolecular interactions. specifically, for dsdna adsorption on a resonator ' s surface, the resonant frequency shift is also dependent on the ionic strength of a solvent, implying the role of molecular interactions on the dynamic behavior of a resonator. this indicates that nanomechanical resonators may enable one to quantify the biomolecular mass, implying the enumeration of biomolecules, as well as gain insight into intermolecular interactions between adsorbed biomolecules on the surface.
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arxiv:0706.3743
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many visual representations, such as volume - rendered images and metro maps, feature a noticeable amount of information loss. at a glance, there seem to be numerous opportunities for viewers to misinterpret the data being visualized, hence undermining the benefits of these visual representations. in practice, there is little doubt that these visual representations are useful. the recently - proposed information - theoretic measure for analyzing the cost - benefit ratio of visualization processes can explain such usefulness experienced in practice, and postulate that the viewers ' knowledge can reduce the potential distortion ( e. g., misinterpretation ) due to information loss. this suggests that viewers ' knowledge can be estimated by comparing the potential distortion without any knowledge and the actual distortion with some knowledge. in this paper, we describe several case studies for collecting instances that can ( i ) support the evaluation of several candidate measures for estimating the potential distortion distortion in visualization, and ( ii ) demonstrate their applicability in practical scenarios. because the theoretical discourse on choosing an appropriate bounded measure for estimating the potential distortion is yet conclusive, it is the real world data about visualization further informs the selection of a bounded measure, providing practical evidence to aid a theoretical conclusion. meanwhile, once we can measure the potential distortion in a bounded manner, we can interpret the numerical values characterizing the benefit of visualization more intuitively.
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arxiv:2103.02502
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the collective phenomena are observed not only in heavy ion collisions, but also in the proton - nucleus and in high - multiplicity $ pp $ collisions. the latest results from this area obtained in atlas are presented. in $ p $ + pb collisions the emission source of particles is measured using the hbt method. the analysis of $ p $ + pb data collected in 2016 provides information on the elliptic flow of charged hadrons and muons. low multiplicity events from $ pp $, $ p $ + pb and peripheral pb + pb collisions are studied with the cumulant methods. a deeper understanding of pb + pb collisions is provided by the analysis of longitudinal fluctuations of the collective flow parameters.
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arxiv:1706.04025
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we investigate the effects of relatively rapid variations of the boundaries of an overmoded cavity on the stochastic properties of its interior acoustic or electromagnetic field. for quasi - static variations, this field can be represented as an ideal incoherent and statistically homogeneous isotropic random scalar or vector field, respectively. a physical model is constructed showing that the field dynamics can be characterized as a generalized diffusion process. the langevin - - it \ ^ { o } and fokker - - planck equations are derived and their associated statistics and distributions for the complex analytic field, its magnitude and energy density are computed. the energy diffusion parameter is found to be proportional to the square of the ratio of the standard deviation of the source field to the characteristic time constant of the dynamic process, but is independent of the initial energy density, to first order. the energy drift vanishes in the asymptotic limit. the time - energy probability distribution is in general not separable, as a result of nonstationarity. a general solution of the fokker - - planck equation is obtained in integral form, together with explicit closed - form solutions for several asymptotic cases. the findings extend known results on statistics and distributions of quasi - stationary ideal random fields ( pure diffusions ), which are retrieved as special cases.
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arxiv:0706.0525
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the magellanic quasars survey ( mqs ) has now increased the number of quasars known behind the magellanic clouds by almost an order of magnitude. all survey fields in the large magellanic cloud ( lmc ) and 70 % of those in the small magellanic cloud ( smc ) have been observed. the targets were selected from the third phase of the optical gravitational lensing experiment ( ogle - iii ) based on their optical variability, mid - ir and / or x - ray properties. we spectroscopically confirmed 758 ( 565 lmc and 193 smc ) quasars behind the clouds, of which 94 % ( 527 lmc and 186 smc ) are newly identified. the mqs quasars have long - term ( 12 years and growing for ogle ), high - cadence light curves, enabling unprecedented variability studies of quasars. the mqs quasars also provide a dense reference grid for measuring both the internal and bulk proper motions of the clouds, and 50 quasars are bright enough ( i < 18 mag ) for absorption studies of the interstellar / galactic ( ism / igm ) medium of the clouds.
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arxiv:1305.6927
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we demonstrate sub - poissonian number differences in four - wave mixing of bose - einstein condensates of metastable helium. the collision between two bose - einstein condensates produces a scattering halo populated by pairs of atoms of opposing velocities, which we divide into several symmetric zones. we show that the atom number difference for opposing zones has sub - poissonian noise fluctuations whereas that of nonopposing zones is well described by shot noise. the atom pairs produced in a dual number state are well adapted to sub shot - noise interferometry and studies of einstein - podolsky - rosen - type nonlocality tests.
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arxiv:1008.0845
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in this paper we provide a complete algebraic characterization of elementary equivalence of rings with a finitely generated additive group in the language of pure rings. the rings considered are arbitrary otherwise.
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arxiv:1609.09810
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we propose a convolutional recurrent sparse auto - encoder model. the model consists of a sparse encoder, which is a convolutional extension of the learned ista ( lista ) method, and a linear convolutional decoder. our strategy offers a simple method for learning a task - driven sparse convolutional dictionary ( cd ), and producing an approximate convolutional sparse code ( csc ) over the learned dictionary. we trained the model to minimize reconstruction loss via gradient decent with back - propagation and have achieved competitive results to ksvd image denoising and to leading csc methods in image inpainting requiring only a small fraction of their run - time.
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arxiv:1711.00328
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not in one of the ideals, then it has multiplicative inverse [ 1 / x, 1 / y ]. endowed with the usual topology, the algebra of intervals forms a topological ring. the group of units of this ring consists of four quadrants determined by the axes, or ideals in this case. the identity component of this group is quadrant i. every interval can be considered a symmetric interval around its midpoint. in a reconfiguration published in 1956 by m warmus, the axis of " balanced intervals " [ x, −x ] is used along with the axis of intervals [ x, x ] that reduce to a point. instead of the direct sum r ⊕ r, { \ displaystyle r \ oplus r, } the ring of intervals has been identified with the hyperbolic numbers by m. warmus and d. h. lehmer through the identification z = 1 2 ( x + y ) + 1 2 ( x − y ) j, { \ displaystyle z = { \ tfrac { 1 } { 2 } } ( x + y ) + { \ tfrac { 1 } { 2 } } ( x - y ) j, } where j 2 = 1. { \ displaystyle j ^ { 2 } = 1. } this linear mapping of the plane, which amounts of a ring isomorphism, provides the plane with a multiplicative structure having some analogies to ordinary complex arithmetic, such as polar decomposition. = = see also = = arc ( geometry ) inequality interval graph interval finite element interval ( statistics ) line segment partition of an interval unit interval = = references = = = = bibliography = = t. sunaga, " theory of interval algebra and its application to numerical analysis " archived 2012 - 03 - 09 at the wayback machine, in : research association of applied geometry ( raag ) memoirs, ggujutsu bunken fukuy - kai. tokyo, japan, 1958, vol. 2, pp. 29 – 46 ( 547 - 564 ) ; reprinted in japan journal on industrial and applied mathematics, 2009, vol. 26, no. 2 - 3, pp. 126 – 143. = = external links = = a lucid interval by brian hayes : an american scientist article provides an introduction. interval computations website archived 2006 - 03 - 02 at the wayback machine interval computations research centers archived 2007 - 02 - 03 at the wayback machine interval notation by george beck, wolfram demonstrations project. weisstein, eric w
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https://en.wikipedia.org/wiki/Interval_(mathematics)
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we develop a unified theory for the second sound in two dimensional materials. previously studied drifting and driftless second sound are two limiting cases of the theory, corresponding to the drift and diffusive part of the energy flux, respectively. we find that due to the presence of quadratic flexural phonons the drifting second sound does not exist in the thermodynamic limit, while the driftless mode is less affected. this is understood as a result of infinite effective inertia of flexual phonons, due to their constant density states and divergent bose - einstein distribution in the long wave length limit. consequently, the group velocity of the drifting mode is smaller than that of the driftless mode. however, upon tensile strain, the velocity of drifting mode becomes larger. both of them increase with tensile strain due to the linearization of the flexural phonon dispersion. our results clarify several puzzles encountered previously and pave the way for exploring wave - like heat transport beyond hydrodynamic regime.
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arxiv:2204.04852
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this paper is about the rainbow dual of the hales jewett number, providing general bounds an anti - hales jewett number for hypercubes of length k and dimension n denoted $ ah ( k, n ). $ the best general bounds this paper provides are : $ ( k - 1 ) ^ n < ah ( k, n ) \ leq \ frac { ( k - 1 ) ^ 2 - 2 } { k - 1 } \ cdot k ^ { n - 1 } + \ frac { k + 1 } { k - 1 }. $ this paper also includes proofs about the specific cases of $ k = 2 $ and $ k = 3 $, where we show that $ ah ( 2, n ) = 2 $ and $ 2 ^ n < ah ( 3, n ) \ leq 3 ^ { n - 1 } - 2 \ cdot3 ^ { n - 4 } + 2 $ for all natural numbers n $ > $ 4. for $ n < 4 $, we have found the exact values : $ ah ( 3, 1 ) = 3 $, $ ah ( 3, 2 ) = 5 $, and $ ah ( 3, 3 ) = 11 $. in the case $ n = 4 $, we have found that $ 23 < ah ( 3, 4 ) \ leq 27 $.
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arxiv:2410.12192
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following the increasing popularity of mobile ecosystems, cybercriminals have increasingly targeted them, designing and distributing malicious apps that steal information or cause harm to the device ' s owner. aiming to counter them, detection techniques based on either static or dynamic analysis that model android malware, have been proposed. while the pros and cons of these analysis techniques are known, they are usually compared in the context of their limitations e. g., static analysis is not able to capture runtime behaviors, full code coverage is usually not achieved during dynamic analysis, etc. whereas, in this paper, we analyze the performance of static and dynamic analysis methods in the detection of android malware and attempt to compare them in terms of their detection performance, using the same modeling approach. to this end, we build on mamadroid, a state - of - the - art detection system that relies on static analysis to create a behavioral model from the sequences of abstracted api calls. then, aiming to apply the same technique in a dynamic analysis setting, we modify chimp, a platform recently proposed to crowdsource human inputs for app testing, in order to extract api calls ' sequences from the traces produced while executing the app on a chimp virtual device. we call this system auntiedroid and instantiate it by using both automated ( monkey ) and user - generated inputs. we find that combining both static and dynamic analysis yields the best performance, with f - measure reaching 0. 92. we also show that static analysis is at least as effective as dynamic analysis, depending on how apps are stimulated during execution, and, finally, investigate the reasons for inconsistent misclassifications across methods.
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arxiv:1803.03448
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direct data - driven design methods for the linear quadratic regulator ( lqr ) mainly use offline or episodic data batches, and their online adaptation has been acknowledged as an open problem. in this paper, we propose a direct adaptive method to learn the lqr from online closed - loop data. first, we propose a new policy parameterization based on the sample covariance to formulate a direct data - driven lqr problem, which is shown to be equivalent to the certainty - equivalence lqr with optimal non - asymptotic guarantees. second, we design a novel data - enabled policy optimization ( deepo ) method to directly update the policy, where the gradient is explicitly computed using only a batch of persistently exciting ( pe ) data. third, we establish its global convergence via a projected gradient dominance property. importantly, we efficiently use deepo to adaptively learn the lqr by performing only one - step projected gradient descent per sample of the closed - loop system, which also leads to an explicit recursive update of the policy. under pe inputs and for bounded noise, we show that the average regret of the lqr cost is upper - bounded by two terms signifying a sublinear decrease in time $ \ mathcal { o } ( 1 / \ sqrt { t } ) $ plus a bias scaling inversely with signal - to - noise ratio ( snr ), which are independent of the noise statistics. finally, we perform simulations to validate the theoretical results and demonstrate the computational and sample efficiency of our method.
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arxiv:2401.14871
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alice is a charismatic quantum cryptographer who believes her parties are unmissable ; bob is a ( relatively ) glamorous string theorist who believes he is an indispensable guest. to prevent possibly traumatic collisions of self - perception and reality, their social code requires that decisions about invitation or acceptance be made via a cryptographically secure variable bias coin toss ( vbct ). this generates a shared random bit by the toss of a coin whose bias is secretly chosen, within a stipulated range, by one of the parties ; the other party learns only the random bit. thus one party can secretly influence the outcome, while both can save face by blaming any negative decisions on bad luck. we describe here some cryptographic vbct protocols whose security is guaranteed by quantum theory and the impossibility of superluminal signalling, setting our results in the context of a general discussion of secure two - party computation. we also briefly discuss other cryptographic applications of vbct.
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arxiv:quant-ph/0508149
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recently we developed a numerical technique to compute chiral symmetry breaking at t = 0 with different current quark masses m0, including the current quark masses of the six standard flavours u, d, s, c, b, t. we also fitted from lattice qcd data the quark - antiquark string tension sigma dependence on temperature t. we now utilize sigma ( t ) to further upgrade the chiral invariant and confinement quark model to finite temperatures t = / = 0. we study the quark mass at finite t and obtain the corresponding chiral crossover at t = tc. the quark mass critical curve has a shape similar, but not identical, to the string tension critical curve. in the case of the lightest quarks, the quark mass and the chiral condensate essentially vanish at t = tc, except for the small explicit chiral symmetry breaking mu and md.
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arxiv:1109.6799
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we provide a new derivation of the anisotropies of the cosmic microwave background ( cmb ), and find an exact expression that can be readily expanded perturbatively. close attention is paid to gauge issues, with the motivation to examine the effect of super - hubble modes on the cmb. we calculate a transfer function that encodes the behaviour of the dipole, and examine its long - wavelength behaviour. we show that contributions to the dipole from adiabatic super - hubble modes are strongly suppressed, even in the presence of a cosmological constant, contrary to claims in the literature. we also introduce a naturally defined cmb monopole, which exhibits closely analogous long - wavelength behaviour. we discuss the geometrical origin of this super - hubble suppression, pointing out that it is a simple reflection of adiabaticity, and hence argue that it will occur regardless of the matter content.
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arxiv:0808.2047
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standard discontinuous galerkin methods, based on piecewise polynomials of degree $ \ qq = 0, 1 $, are considered for temporal semi - discretization for second order hyperbolic equations. the main goal of this paper is to present a simple and straightforward a priori error analysis of optimal order with minimal regularity requirement on the solution. uniform norm in time error estimates are also proved. to this end, energy identities and stability estimates of bthe discrete problem are proved for a slightly more general problem. these are used to prove optimal order a priori error estimates with minimal regularity requirement on the solution. the combination with the classic continuous galerkin finite element discretization in space variable is used, to formulate a full - discrete scheme. the a priori error analysis is presented. numerical experiments are performed to verify the theoretical results.
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arxiv:2006.14082
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moir \ ' e flatbands, occurring, e. g., in twisted bilayer graphene at magic angles, have attracted ample interest due to their high degree of experimental tunability and the intriguing possibility of generating novel strongly interacting phases. here we consider the core problem of coulomb interactions within fractionally filled spin and valley polarized moir \ ' e flatbands and demonstrate that the dual description in terms of holes, which acquire a nontrivial hole dispersion, provides key physical intuition and enables the use of standard perturbative techniques for this strongly correlated problem. in experimentally relevant examples such as abc stacked trilayer and twisted bilayer graphene aligned with boron nitride, it leads to emergent interaction - driven fermi liquid states at electronic filling fractions down to around $ 1 / 3 $ and $ 2 / 3 $ respectively. at even lower filling fractions, the electron density still faithfully tracks the single - hole dispersion while exhibiting distinct non - fermi liquid behavior. most saliently, we provide microscopic evidence that high temperature fractional chern insulators can form in twisted bilayer graphene aligned with hexagonal boron nitride.
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arxiv:1912.04907
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we study a system of all - to - all weakly coupled uniformly expanding circle maps in the thermodynamic limit. the state of the system is described by a probability measure and its evolution is given by the action of a nonlinear operator, also called a self - consistent transfer operator. we prove that when the coupling is sufficiently small, the system has a unique stable state that satisfies a linear response formula when varying the coupling strength.
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arxiv:2001.01317
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bose - einstein condensates of $ ^ { 87 } $ rb atoms are transferred into radio - frequency ( rf ) induced adiabatic potentials and the properties of the corresponding dressed states are explored. we report on measurements of the spin composition of dressed condensates. we also show that adiabatic potentials can be used to trap atom gases in novel geometries, including suspending a cigar - shaped cloud above a curved sheet of atoms.
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arxiv:cond-mat/0605393
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host - guest binding plays a crucial role in the functionality of various systems, and its efficiency is often quantified using the binding free energy, which represents the free - energy difference between the bound and dissociated states. here, we propose a methodology to compute the binding free energy based on the energy representation ( er ) theory of solution that enables us to evaluate the free - energy difference between the systems of interest with the molecular dynamics ( md ) simulations. unlike the other free - energy methods, such as the bennett acceptance ratio ( bar ), the er theory does not require the md simulations for hypothetical intermediate states connecting the systems of interest, leading to reduced computational costs. by constructing the thermodynamic cycle of the binding process that is suitable for the er theory, a robust calculation of the binding free energy is realized. we apply the present method to the self - association of \ textit { n } - methylacetamide ( nma ) in different solvents and the binding of aspirin to $ \ beta $ - cyclodextrin ( cd ) in water. in the former case, the present method estimates that the binding free energy decreases as the solvent polarity decreases. this trend is consistent with the experimental finding. for the latter system, the binding free energies for the two representative cd - aspirin bound complexes, primary ( p ) and secondary ( s ) complexes, are estimated to be $ - 5. 2 \ pm 0. 1 $ and $ - 5. 03 \ pm 0. 09 ~ \ mathrm { kcalmol ^ { - 1 } } $, respectively. these values are satisfactorily close to those from the bar method [ $ - 4. 2 \ pm 0. 2 $ and $ - 4. 1 \ pm 0. 2 \ mathrm { kcal ~ mol ^ { - 1 } } $ for p and s, respectively ]. furthermore, the interaction - energy component analysis reveals that the van der waals interaction between aspirin and cd dominantly contributes to the stabilization of the bound complexes, that is in harmony with the well - known binding mechanism in the cd systems.
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arxiv:2410.04423
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the ten dimensional unified field theory has a 4 dimensional riemannian spacetime and six dimensional calabi yau space structure. the supersymmetric yang mills fields and black holes are solutions in these theories. the formation of primordial black holes in early universe, the collapse to singularity of stellar black holes, the hawking evaporation of microscopic black holes in lhc are topics of observational and theoretical interest. the observation of gamma ray bursts and creation of spectrum of particles and radiation of dark and normal matter occur due to primordial and microscopic black holes. the approach to singularity in black hole interior solutions, require the bogoliubov transforms of susy ym fields in black hole geometries ; both during formation and in evaporation. the hawking effect of radiating black holes is applicable for all the fields. invariants can be defined to give the conditions for these processes.
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arxiv:0705.2572
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cancer screening has been widely recognized as an effective strategy for preventing the disease. despite its effectiveness, determining when to start screening is complicated, because starting too early increases the number of screenings over lifetime and thus costs but starting too late may miss the cancer that could have been prevented. therefore, to make an informed recommendation on the age to start screening, it is necessary to conduct cost - effectiveness analysis to assess the gain in life years relative to the cost of screenings. as more large - scale observational studies become accessible, there is growing interest in evaluating cost - effectiveness based on empirical evidence. in this paper, we propose a unified measure for evaluating cost - effectiveness and a causal analysis for the continuous intervention of screening initiation age, under the multi - state modeling with semi - competing risks. extensive simulation results show that the proposed estimators perform well in realistic scenarios. we perform a cost - effectiveness analysis of the colorectal cancer screening, utilizing data from the large - scale women ' s health initiative. our analysis reveals that initiating screening at age 50 years yields the highest quality - adjusted life years with an acceptable incremental cost - effectiveness ratio compared to no screening, providing real - world evidence in support of screening recommendation for colorectal cancer.
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arxiv:2409.02888
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this work presents a framework for a robot with a multi - fingered hand to freely utilize daily tools, including functional parts like buttons and triggers. an approach heatmap is generated by selecting a functional finger, indicating optimal palm positions on the object ' s surface that enable the functional finger to contact the tool ' s functional part. once the palm position is identified through the heatmap, achieving the functional grasp becomes a straightforward process where the fingers stably grasp the object with low - dimensional inputs using the eigengrasp. as our approach does not need human demonstrations, it can easily adapt to various sizes and designs, extending its applicability to different objects. in our approach, we use directional manipulability to obtain the approach heatmap. in addition, we add two kinds of energy functions, i. e., palm energy and functional energy functions, to realize the eigengrasp. using this method, each robotic gripper can autonomously identify its optimal workspace for functional grasping, extending its applicability to non - anthropomorphic robotic hands. we show that several daily tools like spray, drill, and remotes can be efficiently used by not only an anthropomorphic shadow hand but also a non - anthropomorphic barrett hand.
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arxiv:2401.11681
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while the structure of chromatin has been studied in great detail on length scales below 30 nm, amazingly little is known about the higher - order folding motifs of chromatin in interphase. recent experiments give evidence that the folding may depend locally on gene density and transcriptional activity and show a leveling - off at long distances where approximately $ < r ^ 2 > \ sim o ( 1 ) $. we propose a new model that can explain this leveling - off by the formation of random loops. we derive an analytical expression for the mean square displacement between two beads where the average is taken over the thermal ensemble with a fixed but random loop configuration, while quenched averaging over the ensemble of different loop configurations - - which turns out to be equivalent to averaging over an ensemble of random matrices - - is performed numerically. a detailed investigation of this model shows that loops on all scales are necessary to fit experimental data.
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arxiv:0705.1470
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pt - functionalized graphene harnesses graphene ' s exceptional carrier mobility with pt ' s catalytic activity for hydrogen sensing, yet the mechanisms of pt crystal growth, its interaction with graphene, and the consequent impact on hydrogen sensitivity remain incompletely understood. we develop a high - fidelity equivariant machine - learned interatomic potential ( mlip ) to perform large - scale molecular dynamics ( md ) simulations with near - density functional theory ( dft ) accuracy. our simulations capture key growth stages - including pt nucleation, coalescence, and the formation of either polycrystalline clusters or epitaxial thin films - under varying deposition loadings and rates. transmission electron microscopy and raman measurements validate the predicted morphologies, revealing small approximately spherical clusters at lower pt loadings that evolve into slightly thicker, more planar domains with increased loading. reactive md shows hydrogen dissociates predominantly on pt nanostructures at room temperature, with minimal spillover onto pristine graphene. furthermore, hydrogen uptake increases with pt loading at a diminishing rate, while reaction kinetics are significantly faster at lower coverages and rapidly decline with increasing loading. dft calculations indicate undercoordinated pt clusters induce $ n $ - type doping in graphene, which is diminished when hydrogen adsorption depletes pt electron density, thereby transducing the adsorption events from pt - surfaces to the pt - graphene interface. by correlating deposition conditions, nanostructure morphology, and hydrogen sensing dynamics, our findings suggest that moderate pt loadings can effectively balance sufficient doping with a pronounced pt - mediated electronic response to graphene. these insights underscore the importance of combining dft and mlip simulations with experiments to guide next - generation chemiresistive gas sensor design.
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arxiv:2504.05438
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we first extend our recent experiments of correlation imaging through scattering media to the case of a thick medium, composed of two phase scatterers placed respectively in the image and the fourier planes of the crystal. the spatial correlations between twin photons are still detected but no more in the form of a speckle. second, a numerical simulation of the biphoton wave function is developed and applied to our experimental situation, with a good agreement.
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arxiv:2005.01528
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we apply the coordinate - space method by luescher and weisz to the computation of two - loop diagrams in full qcd with wilson fermions on the lattice. the essential ingredient is the high - precision determination of mixed fermionic - bosonic propagators.
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arxiv:hep-lat/9710074
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quantifying the improvement in human living standard, as well as the city growth in developing countries, is a challenging problem due to the lack of reliable economic data. therefore, there is a fundamental need for alternate, largely unsupervised, computational methods that can estimate the economic conditions in the developing regions. to this end, we propose a new network science - and representation learning - based approach that can quantify economic indicators and visualize the growth of various regions. more precisely, we first create a dynamic network drawn out of high - resolution nightlight satellite images. we then demonstrate that using representation learning to mine the resulting network, our proposed approach can accurately predict spatial gross economic expenditures over large regions. our method, which requires only nightlight images and limited survey data, can capture city - growth, as well as how people ' s living standard is changing ; this can ultimately facilitate the decision makers ' understanding of growth without heavily relying on expensive and time - consuming surveys.
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arxiv:1812.00141
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it is well established that in a market with inclusion of a risk - free asset the single - period mean - variance efficient frontier is a straight line tangent to the risky region, a fact that is the very foundation of the classical capm. in this paper, it is shown that in a continuous - time market where the risky prices are described by ito ' s processes and the investment opportunity set is deterministic ( albeit time - varying ), any efficient portfolio must involve allocation to the risk - free asset at any time. as a result, the dynamic mean - variance efficient frontier, though still a straight line, is strictly above the entire risky region. this in turn suggests a positive premium, in terms of the sharpe ratio of the efficient frontier, arising from the dynamic trading. another implication is that the inclusion of a risk - free asset boosts the sharpe ratio of the efficient frontier, which again contrasts sharply with the single - period case.
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arxiv:0906.0999
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we present two fiberized vector magnetic - field sensors, based on nitrogen - vacancy ( nv ) centers in diamond. the sensors feature sub - nt / $ \ sqrt { \ textrm { hz } } $ magnetic sensitivity. we use commercially available components to construct sensors with a small sensor size, high photon collection, and minimal sensor - sample distance. both sensors are located at the end of optical fibres with the sensor - head freely accessible and robust under movement. these features make them ideal for mapping magnetic fields with high sensitivity and spatial resolution ( $ \ leq $ \, mm ). as a demonstration we use one of the sensors to map the vector magnetic field inside the bore of a $ \ geq $ 100 \, mt halbach array. the vector field sensing protocol translates microwave spectroscopy data addressing all diamonds axes and including double quantum transitions to a 3d magnetic field vector.
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arxiv:2102.11902
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particles are today the main tool to study superfluid turbulence and visualize quantum vortices. in this work, we study the dynamics and the spatial distribution of particles in co - flow and counterflow superfluid helium turbulence in the framework of the two - fluid hall - vinen - bekarevich - khalatnikov ( hvbk ) model. we perform three - dimensional numerical simulations of the hvbk equations along with the particle dynamics that depends on the motion of both fluid components. we find that, at low temperatures, where the superfluid mass fraction dominates, particles strongly cluster in vortex filaments regardless of their physical properties. at higher temperatures, as viscous drag becomes important and the two components become tightly coupled, the clustering dynamics in the coflowing case approach those found in classical turbulence, while under strong counterflow, the particle distribution is dominated by the quasi - two - dimensionalization of the flow.
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arxiv:1910.08444
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the tunability of ar + ion irradiation of co / pd multilayers has been employed to create depth - dependent perpendicular anisotropy gradients. by adjusting the ar + kinetic energy and fluence, the depth and lateral density of the local structural modification are controlled. first - order reversal curve analysis through x - ray magnetic circular dichroism and conventional magnetometry studies show that the local structural damage weakens the perpendicular anisotropy near the surface, leading to a magnetization tilting towards the in - plane direction. the ion irradiation method is complementary to, and may be used in conjunction with, other synthesis approaches to maximize the anisotropy gradient.
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arxiv:1408.1659
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we present linear prediction as a differentiable padding method. for each channel, a stochastic autoregressive linear model is fitted to the padding input by minimizing its noise terms in the least - squares sense. the padding is formed from the expected values of the autoregressive model given the known pixels. we trained the convolutional rvsr super - resolution model from scratch on satellite image data, using different padding methods. linear prediction padding slightly reduced the mean square super - resolution error compared to zero and replication padding, with a moderate increase in time cost. linear prediction padding better approximated satellite image data and rvsr feature map data. with zero padding, rvsr appeared to use more of its capacity to compensate for the high approximation error. cropping the network output by a few pixels reduced the super - resolution error and the effect of the choice of padding method on the error, favoring output cropping with the faster replication and zero padding methods, for the studied workload.
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arxiv:2502.12300
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multimodal sentiment analysis ( msa ) identifies individuals ' sentiment states in videos by integrating visual, audio, and text modalities. despite progress in existing methods, the inherent modality heterogeneity limits the effective capture of interactive sentiment features across modalities. in this paper, by introducing a multi - modality collaborative learning ( mmcl ) framework, we facilitate cross - modal interactions and capture enhanced and complementary features from modality - common and modality - specific representations, respectively. specifically, we design a parameter - free decoupling module and separate uni - modality into modality - common and modality - specific components through semantics assessment of cross - modal elements. for modality - specific representations, inspired by the act - reward mechanism in reinforcement learning, we design policy models to adaptively mine complementary sentiment features under the guidance of a joint reward. for modality - common representations, intra - modal attention is employed to highlight crucial components, playing enhanced roles among modalities. experimental results, including superiority evaluations on four databases, effectiveness verification of each module, and assessment of complementary features, demonstrate that mmcl successfully learns collaborative features across modalities and significantly improves performance. the code can be available at https : / / github. com / smwanghhh / mmcl.
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arxiv:2501.12424
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we extend the post - processing finite - size ( fs ) correction method, developed by kwee, zhang, and krakauer [ phys. rev. lett. 100, 126404 ( 2008 ) ], to spin polarized systems. the method estimates the fs effects in many - body electronic structure calculations of extended systems by a modified density functional theory ( dft ) calculation, without having to repeat expensive many - body simulations. we construct a unified fs dft exchange - correlation functional for spin unpolarized and fully spin polarized systems, under the local density approximation. the results are then interpolated to arbitrary spin polarizations. generalization to other functional forms in dft are discussed. the application of this fs correction method to several typical magnetic systems with varying supercell sizes demonstrates that it consistently removes most of the fs errors, leading to rapid convergence of the many - body results to the infinite size limit.
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arxiv:1108.2739
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