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leading engineers and scientists dedicated to advancing the integration of biology with engineering. mediunite journal is a medical awareness campaign and newspaper that has often published biomedical findings and has cited biomedicine in various research papers. = = references = = = = external links = = bioengineering society biomedical engineering society institute of biological engineering benjoe institute of systems biological engineering american institute of medical and biological engineering american society of agricultural and biological engineers society for biological engineering part of aiche journal of biological engineering, jbe biological engineering transactions munich school of bioengineering
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https://en.wikipedia.org/wiki/Biological_engineering
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we propose a topic modeling approach to the prediction of preferences in pairwise comparisons. we develop a new generative model for pairwise comparisons that accounts for multiple shared latent rankings that are prevalent in a population of users. this new model also captures inconsistent user behavior in a natural way. we show how the estimation of latent rankings in the new generative model can be formally reduced to the estimation of topics in a statistically equivalent topic modeling problem. we leverage recent advances in the topic modeling literature to develop an algorithm that can learn shared latent rankings with provable consistency as well as sample and computational complexity guarantees. we demonstrate that the new approach is empirically competitive with the current state - of - the - art approaches in predicting preferences on some semi - synthetic and real world datasets.
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arxiv:1412.3705
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we address the task of 3d reconstruction in dynamic scenes, where object motions degrade the quality of previous 3d pointmap regression methods, such as dust3r, originally designed for static 3d scene reconstruction. although these methods provide an elegant and powerful solution in static settings, they struggle in the presence of dynamic motions that disrupt alignment based solely on camera poses. to overcome this, we propose d ^ 2ust3r that regresses 4d pointmaps that simultaneiously capture both static and dynamic 3d scene geometry in a feed - forward manner. by explicitly incorporating both spatial and temporal aspects, our approach successfully encapsulates spatio - temporal dense correspondence to the proposed 4d pointmaps, enhancing downstream tasks. extensive experimental evaluations demonstrate that our proposed approach consistently achieves superior reconstruction performance across various datasets featuring complex motions.
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arxiv:2504.06264
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atomistic / continuum coupling method is a class of multiscale computational method for the efficient simulation of crystalline defects. the recently developed blended ghost force correction ( bgfc ) method combines the efficiency of blending methods and the accuracy of qnl type methods. bgfc method can be applied to multi - body interaction potentials and general interfaces. in this paper, we present the formulation, implementation and analysis of the bgfc method in three dimensions. in particular, we focus on the difference and connection with other blending variants, such as energy based blended quasi - continuum method ( bqce ) and force based blended quasi - continuum method ( bqcf ). the theoretical results are justified by a few benchmark numerical experiments with point defects and microcrack in the three dimensional fcc lattice.
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arxiv:2006.06501
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legislation can be viewed as a body of prescriptive rules expressed in natural language. the application of legislation to facts of a case we refer to as statutory reasoning, where those facts are also expressed in natural language. computational statutory reasoning is distinct from most existing work in machine reading, in that much of the information needed for deciding a case is declared exactly once ( a law ), while the information needed in much of machine reading tends to be learned through distributional language statistics. to investigate the performance of natural language understanding approaches on statutory reasoning, we introduce a dataset, together with a legal - domain text corpus. straightforward application of machine reading models exhibits low out - of - the - box performance on our questions, whether or not they have been fine - tuned to the legal domain. we contrast this with a hand - constructed prolog - based system, designed to fully solve the task. these experiments support a discussion of the challenges facing statutory reasoning moving forward, which we argue is an interesting real - world task that can motivate the development of models able to utilize prescriptive rules specified in natural language.
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arxiv:2005.05257
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in this paper we present an econophysic model for the description of shares transactions in a capital market. for introducing the fundamentals of this model we used an analogy between the electrical field produced by a system of charges and the overall of economic and financial information of the shares transactions from the stock - markets. an energetic approach of the rate variation for the shares traded on the financial markets was proposed and studied.
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arxiv:1101.4680
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we present a catalogue of 1696 x - ray sources detected in the massive star forming region ( sfr ) cygnus ob2 and extracted from two archival chandra observations of the center of the region. a deep source extraction routine, exploiting the low background rates of chandra observations was employed to maximize the number of sources extracted. observations at other wavelengths were used to identify low count - rate sources and remove likely spurious sources. monte carlo simulations were also used to assess the authenticity of these sources. we used a bayesian technique to identify optical or near - ir counterparts for 1501 ( 89 % ) of our sources, using deep observations from the int photometric h - alpha survey, the two micron all sky survey, and the ukirt infrared deep sky survey - galactic plane survey. 755 ( 45 % ) of these objects have six - band r ', h - alpha, i ', j, h, and k optical and near - ir photometry. from an analysis of the poisson false - source probabilities for each source we estimate that our x - ray catalogue includes < 1 % of false sources, and an even lower fraction when only sources with optical or near - ir associations are considered. a monte carlo simulation of the bayesian matching scheme allows this method to be compared to more simplified matching techniques and enables the various sources of error to be quantified. the catalogue of 1696 objects presented here includes x - ray broad band fluxes, model fits, and optical and near - ir photometry in what is one of the largest x - ray catalogue of a single sfr to date. the high number of stellar x - ray sources detected from relatively shallow observations confirms the status and importance of cygnus ob2 as one of our galaxy ' s most massive sfrs.
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arxiv:0908.0549
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named entity recognition ( ner ) is a sub - task of natural language processing ( nlp ) that distinguishes entities from unorganized text into predefined categorization. in recent years, a lot of bangla nlp subtasks have received quite a lot of attention ; but named entity recognition in bangla still lags behind. in this research, we explored the existing state of research in bangla named entity recognition. we tried to figure out the limitations that current techniques and datasets face, and we would like to address these limitations in our research. additionally, we developed a gazetteer that has the ability to significantly boost the performance of ner. we also proposed a new ner solution by taking advantage of state - of - the - art nlp tools that outperform conventional techniques.
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arxiv:2401.17206
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for millimeter - wave ( mmwave ) non - orthogonal multiple access ( noma ) communication systems, we propose an innovative near - field ( nf ) transmission framework based on dynamic metasurface antenna ( dma ) technology. in this framework, a base station ( bs ) utilizes the dma hybrid beamforming technology combined with the noma principle to maximize communication efficiency between near - field users ( nus ) and far - field users ( fus ). in conventional communication systems, obtaining channel state information ( csi ) requires substantial pilot signals, significantly reducing system communication efficiency. we propose a beamforming design scheme based on position information to address with this challenge. this scheme does not depend on pilot signals but indirectly obtains csi by analyzing the geometric relationship between user position information and channel models. however, in practical applications, the accuracy of position information is challenging to guarantee and may contain errors. we propose a robust beamforming design strategy based on the worst - case scenario to tackle this issue. facing with the multi - variable coupled non - convex problems, we employ a dual - loop iterative joint optimization algorithm to update beamforming using block coordinate descent ( bcd ) and derive the optimal power allocation ( pa ) expression. we analyze its convergence and complexity to verify the proposed algorithm ' s performance and robustness thoroughly. we validate the theoretical derivation of the csi error bound through simulation experiments. numerical results show that our proposed scheme performs better than traditional beamforming schemes. additionally, the transmission framework exhibits strong robustness to nu and fu position errors, laying a solid foundation for the practical application of mmwave noma communication systems.
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arxiv:2409.15894
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this project compares the performance of simultaneous transmit and receive ( str ) and enhanced multi - link single radio ( emlsr ) within multi - link operation ( mlo ) in wi - fi 7 networks. using the ns - 3 simulator, we evaluate both techniques under various scenarios, including changes in modulation coding scheme ( mcs ), bandwidth, link quality, and interference levels. key performance metrics such as latency, throughput, and energy efficiency are analyzed to determine the trade - offs between str and emlsr. the results demonstrate that str achieves higher throughput and lower latency due to dual - link utilization, making it suitable for high - load environments. in contrast, emlsr balances energy efficiency with responsiveness, making it advantageous for power - sensitive applications. this analysis provides insights into the strengths and limitations of str and emlsr, guiding optimal deployment strategies for future wi - fi 7 networks.
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arxiv:2501.04149
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hydrodynamic computations of nonlinear cepheid pulsation models with periods from 20 to 100 day on the evolutionary stage of core helium burning were carried out. equations of radiation hydrodynamics and time - - dependent convection were solved with initial conditions obtained from selected models of evolutionary sequences of population i stars with initial masses from $ 8m _ \ odot $ to $ 12. 5m _ \ odot $. for each crossing of the instability strip the pulsation period $ \ pi $ and the rate of period change $ \ dot \ pi $ were derived as a function of evolutionary time. comparing results of our computations with observational estimates of $ \ pi $ and $ \ dot \ pi $ we determined fundamental parameters ( the age, the mass, the luminosity and the radius ) of seven long - - period cepheids. theoretical estimates of the stellar radius are shown to agree with radius measurements by the baade - - wesselink technique within 3 \ % for rs ~ pup and gy ~ sge whereas for sv ~ vul the disagreement between theory and observations does not exceed 10 \ %.
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arxiv:1809.03458
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we report the development and first results of an instrument called low layer scidar ( lolas ) which is aimed at the measurement of optical - turbulence profiles in the atmospheric boundary layer with high altitude - resolution. the method is based on the generalized scidar ( gs ) concept, but unlike the gs instruments which need a 1 - m or larger telescope, lolas is implemented on a dedicated 40 - cm telescope, making it an independent instrument. the system is designed for widely separated double - star targets, which enables the high altitude - resolution. using a 20000 - separation double - star, we have obtained turbulence profiles with unprecedented 12 - m resolution. the system incorporates necessary novel algorithms for autoguiding, autofocus and image stabilisation. the results presented here were obtained at mauna kea observatory. they show lolas capabilities but cannot be considered as representative of the site. a forthcoming paper will be devoted to the site characterisation. the instrument was built as part of the ground layer turbulence monitoring campaign on mauna kea for gemini observatory.
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arxiv:0805.4784
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intelligent surface ( is ) is envisioned as a promising technology for the sixth - generation ( 6g ) wireless networks, which can effectively reconfigure the wireless propagation environment via dynamically controllable signal reflection / transmission. in particular, integrating passive intelligent surface ( is ) into the base station ( bs ) is a novel solution to enhance the wireless network throughput and coverage both cost - effectively and energyefficiently. in this article, we provide an overview of is - integrated bss for wireless networks, including their motivations, practical architectures, and main design issues. moreover, numerical results are presented to compare the performance of different is - integrated bs architectures as well as the conventional bs without is. finally, promising directions are pointed out to stimulate future research on is - bs / terminal integration in wireless networks.
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arxiv:2407.10986
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the local group provides an interesting and representative sample of galaxies in the rest of the universe. the high accuracy with which many problems can be addressed in local group galaxies is of paramount importance for understanding galaxy formation and evolution. this contribution presents a short review of overall local group properties followed by short discussions of five topics in which the study of local group members provides particularly significant information. these topics are only examples of the usefulness and potential of local group research. the five selected topics are the formation of the milky way, galaxy destruction and tidal streams, detailed galactic chemical evolution, star formation history determination, and low surface brightness extended structures.
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arxiv:astro-ph/0310766
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we have carried out a multi - wavelength study of the infrared dust bubble n6 to extensively investigate the molecular environs and star - forming activities therein. mapping observations in 12co j = 1 - 0 and 13co j = 1 - 0 performed with the purple mountain observatory 13. 7 - m telescope have revealed four velocity components. comparison between distributions of each component and the infrared emission suggests that three components are correlated with n6. there are ten molecular clumps detected. among them, five have reliable detection in both 12co and 13co and have similar lte and non - lte masses ranging from 200 to higher than 5, 000 m _ sun. with larger gas masses than virial masses, these five clumps are gravitationally unstable and have potential to collapse to form new stars. the other five clumps are only reliably detected in 12co and have relatively small masses. five clumps are located on the border of the ring structure and four of them are elongated along the shell. this is well in agreement with the collect and collapse scenario. the detected velocity gradient reveals that the ring structure is still under expansion due to stellar winds from the exciting star ( s ). furthermore, 99 young stellar objects have been identified based on their infrared colors. a group of ysos reside inside the ring, indicating active star formation in n6. although no confirmative features of triggered star formation detected, the bubble and the enclosed hii region have profoundly reconstructed the natal could and altered the dynamics therein.
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arxiv:1411.0767
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the study of the lefschetz properties of artinian graded algebras was motivated by the hard lefschetz theorem for a smooth complex projective variety, a breakthrough in algebraic topology and geometry. over the last few years, this topic has attracted increasing attention from mathematicians in various areas. here, we suggest some important open problems about or related to lefschetz properties of artinian graded algebras with the ultimate aim to attract the attention of young researchers from different areas.
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arxiv:2311.03081
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in this paper we obtain an effective metric describing a regular and rotating magnetic black hole ( bh ) solution with a yang - mills electromagnetic source in einstein - yang - mills ( eym ) theory using the newman - - janis algorithm via the non - complexification radial coordinate procedure. we then study the bh shadow and the quasinormal modes ( qnms ) for massless scalar and electromagnetic fields and the quasiperiodic oscillations ( qpos ). to this end, we also study the embedding diagram for the rotating eym bh. the energy conditions, shadow curvature radius, topology and the dynamical evolution of scalar and electromagnetic perturbations using the time domain integration method are investigated. we show that the shadow radius decreases by increasing the magnetic charge, while the real part of qnms of scalar and electromagnetic fields increases by increasing the magnetic charge. this result is consistent with the inverse relation between the shadow radius and the real part of qnms. in addition, we have studied observational constraints on the eym parameter $ \ lambda $ via frequency analysis of qpos and the eht data of shadow cast by the m87 central black hole. we also find that the decaying rate of the eym bh is slower than that of the neutral and ends up with a tail. we argue that the rotating eym black hole can be distinguished from the kerr - newman black hole with a magnetic charge based on the difference between the angular diameters of their shadows.
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arxiv:2008.08450
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we present an expectation - maximization algorithm for the fractal inverse problem : the problem of fitting a fractal model to data. in our setting the fractals are iterated function systems ( ifs ), with similitudes as the family of transformations. the data is a point cloud in $ { \ mathbb r } ^ h $ with arbitrary dimension $ h $. each ifs defines a probability distribution on $ { \ mathbb r } ^ h $, so that the fractal inverse problem can be cast as a problem of parameter estimation. we show that the algorithm reconstructs well - known fractals from data, with the model converging to high precision parameters. we also show the utility of the model as an approximation for datasources outside the ifs model class.
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arxiv:1706.03149
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retrieval - augmented generation ( rag ) improves the service quality of large language models by retrieving relevant documents from credible literature and integrating them into the context of the user query. recently, the rise of the cloud rag service has made it possible for users to query relevant documents conveniently. however, directly sending queries to the cloud brings potential privacy leakage. in this paper, we are the first to formally define the privacy - preserving cloud rag service to protect the user query and propose remoterag as a solution regarding privacy, efficiency, and accuracy. for privacy, we introduce $ ( n, \ epsilon ) $ - distancedp to characterize privacy leakage of the user query and the leakage inferred from relevant documents. for efficiency, we limit the search range from the total documents to a small number of selected documents related to a perturbed embedding generated from $ ( n, \ epsilon ) $ - distancedp, so that computation and communication costs required for privacy protection significantly decrease. for accuracy, we ensure that the small range includes target documents related to the user query with detailed theoretical analysis. experimental results also demonstrate that remoterag can resist existing embedding inversion attack methods while achieving no loss in retrieval under various settings. moreover, remoterag is efficient, incurring only $ 0. 67 $ seconds and $ 46. 66 $ kb of data transmission ( $ 2. 72 $ hours and $ 1. 43 $ gb with the non - optimized privacy - preserving scheme ) when retrieving from a total of $ 10 ^ 6 $ documents.
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arxiv:2412.12775
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over the finite field with two elements, we present a method for obtaining explicit expressions for the number of rank i matrices of the form a above b, where a is persymmetric ( a matrix [ a ( i, j ) ] is persymmetric if a ( i, j ) = a ( r, s ) for i + j = r + s ).
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arxiv:0711.1306
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we build upon estrin et al. ( 2019 ) to develop a general constrained nonlinear optimization algorithm based on a smooth penalty function proposed by fletcher ( 1970, 1973b ). although fletcher ' s approach has historically been considered impractical, we show that the computational kernels required are no more expensive than those in other widely accepted methods for nonlinear optimization. the main kernel for evaluating the penalty function and its derivatives solves structured linear systems. when the matrices are available explicitly, we store a single factorization each iteration. otherwise, we obtain a factorization - free optimization algorithm by solving each linear system iteratively. the penalty function shows promise in cases where the linear systems can be solved efficiently, e. g., pde - constrained optimization problems when efficient preconditioners exist. we demonstrate the merits of the approach, and give numerical results on several pde - constrained and standard test problems.
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arxiv:1912.02093
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we propose a laser - based method for the preparation of high - energy polarized electrons, from the ionization of isolated spin - polarized hydrogen ( sph ) atoms. the sph atoms are prepared from the photodissociation of hcl, using two consecutive uv pulses of ps duration. by appropriately timing and focusing the pulses, we can spatially separate the highly polarized sph from other unwanted photoproducts, which then act as the target for the acceleration lasers. we show how elastic collisions define number density $ n $ and polarization p regimes ( $ 10 ^ { 16 } \ leq $ $ n $ $ \ leq 10 ^ { 18 } $ cm $ ^ { - 3 } $, 0. 99 $ \ geq $ p $ \ geq $ 0. 40 ) for the pre - polarized targets, and use particle - in - cell simulations to demonstrate the method ' s feasibility.
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arxiv:2403.05651
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we say that a function $ f : [ 0, 1 ] \ rightarrow \ r $ is \ emph { nowhere $ l ^ q $ } if, for each nonvoid open subset $ u $ of $ [ 0, 1 ] $, the restriction $ f | _ u $ is not in $ l ^ q ( u ) $. for a fixed $ 1 \ leq p < \ infty $, we will show that the set $ $ s _ p \ doteq { f \ in l ^ p [ 0, 1 ] : f is nowhere $ l ^ q $, for each p < q \ leq \ infty }, $ $ united with $ { 0 } $, contains an isometric and complemented copy of $ \ ell _ p $. in particular, this improves a result from g. botelho, v. f \ ' avaro, d. pellegrino, and j. b. seoane - sep \ ' ulveda, $ l _ p [ 0, 1 ] \ setminus \ cup _ { q > p } l _ q [ 0, 1 ] $ is spaceable for every $ p > 0 $, preprint, 2011., since $ s _ p $ turns out to be spaceable. in addition, our result is a generalization of one of the main results from s. g { \ l } \ c { a } b, p. l. kaufmann, and l. pellegrini, spaceability and algebrability of sets of nowhere integrable functions, preprint, 2011.
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arxiv:1110.5774
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video summaries or highlights are a compelling alternative for exploring and contextualizing unprecedented amounts of video material. however, the summarization process is commonly automatic, non - transparent and potentially biased towards particular aspects depicted in the original video. therefore, our aim is to help users like archivists or collection managers to quickly understand which summaries are the most representative for an original video. in this paper, we present empirical results on the utility of different types of visual explanations to achieve transparency for end users on how representative video summaries are, with respect to the original video. we consider four types of video summary explanations, which use in different ways the concepts extracted from the original video subtitles and the video stream, and their prominence. the explanations are generated to meet target user preferences and express different dimensions of transparency : concept prominence, semantic coverage, distance and quantity of coverage. in two user studies we evaluate the utility of the visual explanations for achieving transparency for end users. our results show that explanations representing all of the dimensions have the highest utility for transparency, and consequently, for understanding the representativeness of video summaries.
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arxiv:2005.00465
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we compactify the pure spinor formalism on a k3 surface. the pure spinor splits into a six - dimensional pure spinor, a projective superspace harmonic, and 6 non - covariant variables. a homological algebra argument reduces the calculation of the cohomology of the berkovits differential to a " small " hilbert space which is the string - theoretic analogue of projective superspace. the description of the physical state conditions is facilitated by lifting to the full harmonic superspace, which is accomplished by the introduction of the missing harmonics as non - minimal variables. finally, contact with the hybrid formalism is made by returning to the small hilbert space and fermionizing the projective parameter.
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arxiv:1109.3200
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this research investigates using a mixed - precision iterative refinement method using posit numbers instead of the standard ieee floating - point format. the method is applied to solve a general linear system represented by the equation $ ax = b $, where $ a $ is a large sparse matrix. various scaling techniques, such as row and column equilibration, map the matrix entries to higher - density regions of machine numbers before performing the $ o ( n ^ 3 ) $ factorization operation. low - precision lu factorization followed by forward / backward substitution provides an initial estimate. the results demonstrate that a 16 - bit posit configuration combined with equilibration produces accuracy comparable to ieee half - precision ( fp16 ), indicating a potential for achieving a balance between efficiency and accuracy.
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arxiv:2408.13400
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rave, the radial velocity experiment, is a large spectroscopic survey which collects spectroscopic data for stars in the southern hemisphere. rave uses the aao schmidt telescope with a wavelength coverage similar to gaia but a lower resolution of r = 7, 500. since 2003, rave collected over 500, 000 spectra providing an unprecedented dataset to study the structure and kinematics of the milky way and its stellar populations. in this review, we will summarize the main results obtained using the rave catalogues.
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arxiv:1210.0363
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we revisit the original hawk - dove game with slight modifications to payoff values while maintaining the fundamental principles of interaction. the practical robustness of the theoretical tools of game theory is tested on a simulated population of hawks and doves with varying initial population distributions and peak growth rates. additionally, we aim to find conditions in which the entire community fails or becomes a single - species population. the results show that the predicted community distribution is established by the majority of communities but fails to exist in communities with extreme initial imbalances in species distribution and insufficient growth rates. we also find that greater growth rates can compensate for more imbalanced initial conditions and that more balanced initial conditions can compensate for lower growth rates. overall, the simple theoretical model is a strong predictor of the stable behavior of simulated multi - species communities.
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arxiv:2304.00687
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strange nuggets are believed to be among the relics of the early universe. they appear as dark matter due to their low charge - to - mass ratio. their distribution is believed to be the same as that of dark matter. as such, they could be accreted by high magnetic field objects and their collisions with pulsars are inevitable. pulsar glitches are commonly seen as sudden spin - ups in pulsar frequency. it is still an open debate with regard to mechanisms giving rise to such a phenomenon. however, there is a class of sudden changes in pulsar spin frequency known as microglitches. these event are characterized by sudden small change in pulsar spin frequency ( $ \ delta \ nu / \ nu \ approx \ pm 10 ^ { - 9 } $ ). clearly, the negative signature seen in some of the events is inconsistent with the known glitch mechanisms. in this analysis, we suggest that accretion of strange nuggets with pulsars could readily give rise to microglitch events. the signature of the events depends on the energy of the strange nuggets and line of interaction.
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arxiv:2007.04786
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we study a random resistors network model on a euclidean geometry $ \ bt { z } ^ d $. we formulate the model in terms of a variational principle and show that, under appropriate boundary conditions, the thermodynamic limit of the dissipation per unit volume is finite almost surely and in the mean. moreover, we show that for a particular thermodynamic limit the result is also independent of the boundary conditions.
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arxiv:cond-mat/9605132
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we show that for $ k = 0, 1 $ the graph of a continuous mapping $ f : d \ to \ mathbb { r } ^ k \ times \ mathbb { c } ^ p $, defined on a domain $ d $ in $ \ mathbb { c } ^ n \ times \ mathbb { r } ^ k $, is locally foliated by complex $ n $ - dimensional submanifolds if and only if its complement is $ n $ - pseudoconvex ( in the sense of rothstein ) relatively to $ ( d \ times \ mathbb { r } ^ k ) \ times \ mathbb { c } ^ p \ subset \ mathbb { c } ^ { n } \ times \ mathbb { c } ^ k \ times \ mathbb { c } ^ p $.
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arxiv:2004.01797
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the time evolution of thermal states of a mirror released from a tight harmonic trap is studied. after the release no dissipation is assumed to be present and the mirror is, after a time delay, kicked into a momentum superposition state. the thermal character of the initial state washes out the telltale interference patterns of the superposition but no loss of coherence is found. this investigation resolves a controversy about decoherence - - without - - dissipation and shows that entrained measurements can be surprisingly insensitive to temperature effects.
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arxiv:1109.1818
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the atacama cosmology telescope has measured the angular power spectra of microwave fluctuations to arcminute scales at frequencies of 148 and 218 ghz, from three seasons of data. at small scales the fluctuations in the primordial cosmic microwave background ( cmb ) become increasingly obscured by extragalactic foregounds and secondary cmb signals. we present results from a nine - parameter model describing these secondary effects, including the thermal and kinematic sunyaev - zel ' dovich ( tsz and ksz ) power ; the clustered and poisson - like power from cosmic infrared background ( cib ) sources, and their frequency scaling ; the tsz - cib correlation coefficient ; the extragalactic radio source power ; and thermal dust emission from galactic cirrus in two different regions of the sky. in order to extract cosmological parameters, we describe a likelihood function for the act data, fitting this model to the multi - frequency spectra in the multipole range 500 < ell < 10000. we extend the likelihood to include spectra from the south pole telescope at frequencies of 95, 150, and 220 ghz. accounting for different radio source levels and galactic cirrus emission, the same model provides an excellent fit to both datasets simultaneously, with chi2 / dof = 675 / 697 for act, and 96 / 107 for spt. we then use the multi - frequency likelihood to estimate the cmb power spectrum from act in bandpowers, marginalizing over the secondary parameters. this provides a simplified ` cmb - only ' likelihood in the range 500 < ell < 3500 for use in cosmological parameter estimation.
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arxiv:1301.0776
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the ecocropsaid dataset is a comprehensive collection of 5, 400 aerial images captured between 2014 and 2018 using the google earth application. this dataset focuses on five key economic crops in thailand : rice, sugarcane, cassava, rubber, and longan. the images were collected at various crop growth stages : early cultivation, growth, and harvest, resulting in significant variability within each category and similarities across different categories. these variations, coupled with differences in resolution, color, and contrast introduced by multiple remote imaging sensors, present substantial challenges for land use classification. the dataset is an interdisciplinary resource that spans multiple research domains, including remote sensing, geoinformatics, artificial intelligence, and computer vision. the unique features of the ecocropsaid dataset offer opportunities for researchers to explore novel approaches, such as extracting spatial and temporal features, developing deep learning architectures, and implementing transformer - based models. the ecocropsaid dataset provides a valuable platform for advancing research in land use classification, with implications for optimizing agricultural practices and enhancing sustainable development. this study explicitly investigates the use of deep learning algorithms to classify economic crop areas in northeastern thailand, utilizing satellite imagery to address the challenges posed by diverse patterns and similarities across categories.
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arxiv:2411.02762
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medical imaging segmentation is a highly active area of research, with deep learning - based methods achieving state - of - the - art results in several benchmarks. however, the lack of standardized tools for training, testing, and evaluating new methods makes the comparison of methods difficult. to address this, we introduce the medical imaging segmentation toolkit ( mist ), a simple, modular, and end - to - end medical imaging segmentation framework designed to facilitate consistent training, testing, and evaluation of deep learning - based medical imaging segmentation methods. mist standardizes data analysis, preprocessing, and evaluation pipelines, accommodating multiple architectures and loss functions. this standardization ensures reproducible and fair comparisons across different methods. we detail mist ' s data format requirements, pipelines, and auxiliary features and demonstrate its efficacy using the brats adult glioma post - treatment challenge dataset. our results highlight mist ' s ability to produce accurate segmentation masks and its scalability across multiple gpus, showcasing its potential as a powerful tool for future medical imaging research and development.
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arxiv:2407.21343
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the exactness of the semiclassical method for three - dimensional problems in quantum mechanics is analyzed. the wave equation appropriate in the quasiclassical region is derived. it is shown that application of the standard leading - order wkb quantization condition to this equation reproduces exact energy eigenvalues for all solvable spherically symmetric potentials.
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arxiv:quant-ph/9911075
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we consider an integral dissipative operator in its brodskii - livshits triangular representation. the main question we are concerned with is similarity of the operator to a normal one. we obtain necessary as well as sufficient conditions for the similarity. the study is based on functional model technique.
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arxiv:math/0111124
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retrieving and analyzing transit feeds relies on working with analytical workflows that can handle the massive volume of data streams that are relevant to understand the dynamics of transit networks which are entirely deterministic in the geographical space in which they takes place. in this paper, we consider the fundamental issues in developing a streaming analytical workflow for analyzing the continuous arrival of multiple, unbounded transit data feeds for automatically processing and enriching them with additional information containing higher level concepts accordingly to a particular mobility context. this workflow consists of three tasks : ( 1 ) stream data retrieval for creating time windows ; ( 2 ) data cleaning for handling missing data, overlap data or redundant data ; and ( 3 ) data contextualization for computing actual arrival and departure times as well as the stops and moves during a bus trip, and also performing mobility context computation. the workflow was implemented in a hadoop cloud ecosystem using data streams from the codiac transit system of the city of moncton, nb. the map ( ) function of mapreduce is used to retrieve and bundle data streams into numerous clusters which are subsequently handled in a parallel manner by the reduce ( ) function in order to execute the data contextualization step. the results validate the need for cloud computing for achieving high performance and scalability, however, due to the delay in computing and networking, it is clear that data cleaning tasks should not only be deployed using a cloud environment, paving the way to combine it with fog computing in the near future.
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arxiv:1706.04722
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we demonstrate that the high energy nonrelativistic asymptotic for the photoionization cross section in a central field $ v ( r ) $ can be expressed in terms of the asymptotic of the fourier transform $ v ( p ) $ of the field. we show that the cross sections drop in the same way for the fields with the coulomb short distance behavior. the character of the cross sections energy behavior is related to the analytical properties of the function $ v ( r ) $. the cross sections exhibit power drop for the potentials which have singularities an the real axis. they suffer the exponential drop if $ v ( r ) $ has singularities in the complex plane.
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arxiv:1612.08833
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combinatorial network optimization algorithms that compute optimal structures taking into account edge weights form the foundation for many network protocols. examples include shortest path routing, minimal spanning tree computation, maximum weighted matching on bipartite graphs, etc. we present clrmr, the first online learning algorithm that efficiently solves the stochastic version of these problems where the underlying edge weights vary as independent markov chains with unknown dynamics. the performance of an online learning algorithm is characterized in terms of regret, defined as the cumulative difference in rewards between a suitably - defined genie, and that obtained by the given algorithm. we prove that, compared to a genie that knows the markov transition matrices and uses the single - best structure at all times, clrmr yields regret that is polynomial in the number of edges and nearly - logarithmic in time.
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arxiv:1109.1606
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nonparametric tests via kernel embedding of distributions have witnessed a great deal of practical successes in recent years. however, statistical properties of these tests are largely unknown beyond consistency against a fixed alternative. to fill in this void, we study here the asymptotic properties of goodness - of - fit, homogeneity and independence tests using gaussian kernels, arguably the most popular and successful among such tests. our results provide theoretical justifications for this common practice by showing that tests using gaussian kernel with an appropriately chosen scaling parameter are minimax optimal against smooth alternatives in all three settings. in addition, our analysis also pinpoints the importance of choosing a diverging scaling parameter when using gaussian kernels and suggests a data - driven choice of the scaling parameter that yields tests optimal, up to an iterated logarithmic factor, over a wide range of smooth alternatives. numerical experiments are also presented to further demonstrate the practical merits of the methodology.
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arxiv:1909.03302
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the otfs ( orthogonal time frequency space ) is widely acknowledged for its ability to combat doppler spread in time - varying channels. in this paper, another advantage of otfs over ofdm ( orthogonal frequency division multiplexing ) will be demonstrated : much reduced channel training overhead. specifically, the sparsity of the channel in delay - doppler ( d - d ) domain implies strong correlation of channel gains in time - frequency ( t - f ) domain, which can be harnessed to reduce channel training overhead through interpolation. an immediate question is how much training overhead is needed in doubly - dispersive channels? a conventional belief is that the overhead is only dependent on the product of delay and doppler spreads, but we will show that it ' s also dependent on the t - f window size. the finite t - f window leads to infinite spreading in d - d domain, and aliasing will be inevitable after sampling in t - f domain. two direct consequences of the aliasing are increased channel training overhead and interference. another factor contributing to channel estimation error is the inter - symbol - carrier - interference ( isci ), resulting from the uncertainty principle. both aliasing and isci are considered in channel modelling, a low - complexity algorithm is proposed for channel estimation and interpolation through fft. a large t - f window is necessary for reduced channel training overhead and aliasing, but increases processing delay. fortunately, we show that the proposed algorithm can be implemented in a pipeline fashion. further more, we showed that data - aided channel tracking is possible in d - d domain to further reduce the channel estimation frequency, i. e., channel extrapolation. the impacts of aliasing and isci on channel interpolation error are analyzed.
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arxiv:2408.09381
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for $ \ alpha > 1 $ we represent a real number in $ ( 0, 1 ] $ in the form \ [ \ sum _ { i = 1 } ^ { \ infty } ( \ alpha - 1 ) ^ { i - 1 } \ alpha ^ { - ( d _ { 1 } + \ dots + d _ { i } ) } \ ] with $ d _ { i } \ in \ mathbb { n } $. we discuss ergodic theoretical and dimension theoretical aspects of this expansion. furthermore we study their base - change - transformation.
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arxiv:2406.10919
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we construct the gauge invariant three - photon decay amplitude of particle - antiparticle bound states modeled by the dyson - schwinger and bethe - salpeter equations. application to the quark - antiquark ( $ q \ bar { q } $ ) bound states is emphasized. an essential aspect of our formulation is that it applies to any underlying quantum field theoretic model of the $ q \ bar { q } $ system, and not just to models, like exact qcd, where the quark self - energy $ \ sigma $ couples to the electromagnetic field solely via dressed quark propagators. in this way, applications to effective field theories and other qcd motivated models are envisioned. the three - photon decay amplitude is constructed by attaching currents to all possible places in the feynman diagrams contributing to the dressed quark propagator. the gauge invariance of our construction is thus a direct consequence of respecting the underlying structure of the quantum field theory determining the dynamics. in the resultant expression for the three - photon decay amplitude, all the basic ingredients consisting of the bound state wave function, the final - state interaction $ q \ bar { q } $ $ t $ matrix, the dressed quark propagator, and dressed quark currents, are determined by a universal bethe - salpeter kernel.
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arxiv:1410.6216
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we construct new invariants and give several theorems which determine in general ( i ) the number of physically meaningful phases in quark mass matrices and ( ii ) which elements of these matrices can be rendered real by rephasings. we illustrate our results with simple models.
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arxiv:hep-ph/9310307
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we consider the problem of an overdamped brownian particle moving in multiscale potential with n + 1 characteristic length scales : the macroscale and n separated microscales. we show that the coarse - grained dynamics is given by an overdamped langevin equation with respect to the free energy and with a space dependent diffusion tensor, the calculation of which requires the solution of n fully coupled poisson equations. we study in detail the structure of the bifurcation diagram for one - dimensional problems and we show that the multiscale structure in the potential leads to hysteresis effects and to noise - induced transitions. furthermore, we obtain an explicit formula for the effective diffusion coefficient for a self - similar separable potential and we investigate the limit of infinitely many small scales.
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arxiv:1604.04530
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since the first experimental realization of bose - einstein condensation in cold atomic gases in 1995 there has been a surge of activity in this field. ingenious experiments have allowed us to probe matter close to zero temperature and reveal some of the fascinating effects quantum mechanics has bestowed on nature. it is a challenge for mathematical physicists to understand these various phenomena from first principles, that is, starting from the underlying many - body schr \ " odinger equation. recent progress in this direction concerns mainly equilibrium properties of dilute, cold quantum gases. we shall explain some of the results in this article, and describe the mathematics involved in understanding these phenomena. topics include the ground state energy and the free energy at positive temperature, the effect of interparticle interaction on the critical temperature for bose - einstein condensation, as well as the occurrence of superfluidity and quantized vortices in rapidly rotating gases.
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arxiv:0908.3686
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one of the leading issues in high - $ \ rm t _ c $ copper oxide superconductors is the origin of the pseudogap phase in the underdoped regime of their phase diagram. using polarized neutron diffraction, a novel magnetic order has been identified as an hidden order parameter of the pseudogap as the transition temperature corresponds to what is expected for the pseudogap. the observed magnetic order preserves translational symmetry as predicted for orbital moments in the circulating current theory. being now reported in three different cuprates familles, it appears as a universal phenomenon whatever the crystal structure ( with single cuo $ _ 2 $ layer or bilayer per unit cell ). to date, it is the first direct evidence of an hidden order parameter characterizing the pseudogap phase of high - $ \ rm t _ c $ cuprates.
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arxiv:1101.1786
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nova explosions occur on the white dwarf component of a cataclysmic variable binary stellar system that is accreting matter lost by its companion. when sufficient material has been accreted by the white dwarf, a thermonuclear runaway occurs and ejects material in what is observed as a classical nova explosion. we describe both the recent advances in our understanding of the progress of the outburst and outline some of the puzzles that are still outstanding. we report on the effects of improving both the nuclear reaction rate library and including a modern nuclear reaction network in our one - dimensional, fully implicit, hydrodynamic computer code. in addition, there has been progress in observational studies of supernovae ia with implications about the progenitors and we discuss that in this review.
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arxiv:1605.04294
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we study the piecewise stationary combinatorial semi - bandit problem with causally related rewards. in our nonstationary environment, variations in the base arms ' distributions, causal relationships between rewards, or both, change the reward generation process. in such an environment, an optimal decision - maker must follow both sources of change and adapt accordingly. the problem becomes aggravated in the combinatorial semi - bandit setting, where the decision - maker only observes the outcome of the selected bundle of arms. the core of our proposed policy is the upper confidence bound ( ucb ) algorithm. we assume the agent relies on an adaptive approach to overcome the challenge. more specifically, it employs a change - point detector based on the generalized likelihood ratio ( glr ) test. besides, we introduce the notion of group restart as a new alternative restarting strategy in the decision making process in structured environments. finally, our algorithm integrates a mechanism to trace the variations of the underlying graph structure, which captures the causal relationships between the rewards in the bandit setting. theoretically, we establish a regret upper bound that reflects the effects of the number of structural - and distribution changes on the performance. the outcome of our numerical experiments in real - world scenarios exhibits applicability and superior performance of our proposal compared to the state - of - the - art benchmarks.
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arxiv:2307.14138
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we study local g - shtukas with level structure over a base scheme whose newton polygons are constant on the base. we show that after a finite base change and after passing to an \ ' etale covering, such a local g - shtuka is isogenous to a completely slope divisible one, generalizing corresponding results for p - divisible groups by oort and zink. as an application we establish a product structure up to finite morphism on the closed newton stratum of the universal deformation of a local g - shtuka, similarly to oort ' s foliations for p - divisible groups and abelian varieties. this also yields bounds on the dimensions of affine deligne - lusztig varieties and proves equidimensionality of affine deligne - lusztig varieties in the affine grassmannian.
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arxiv:1002.2387
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in a recent paper chatterji and niblo proved that a geodesic metric space is gromov hyperbolic if and only if the intersection of any two closed balls has uniformly bounded eccentricity. in their paper, the authors raise the question whether a geodesic metric space with the property that the intersection of any two closed balls has eccentricity 0, is necessarily a real tree. the purpose of this note is to answer this question affirmatively. we also partially improve the main result of chatterji and niblo by showing that already sublinear eccentricity implies gromov hyperbolicity.
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arxiv:math/0603539
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for $ a $ a hopf algebra of arbitrary dimension over a field $ k $, it is well - known that if $ a $ has nonzero integrals, or, in other words, if the coalgebra $ a $ is co - frobenius, then the space of integrals is one - dimensional and the antipode of $ a $ is bijective. bulacu and caenepeel recently showed that if $ h $ is a dual quasi - hopf algebra with nonzero integrals, then the space of integrals is one - dimensional, and the antipode is injective. in this short note we show that the antipode is bijective.
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arxiv:0805.2401
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in this paper we continue with the program to explore the topography of the space of w - type algebras. in the present case, the starting point is the work of khesin, lyubashenko and roger on the algebra of q - deformed pseudodifferential symbols and their associated integrable hierarchies. the analysis goes on by studying the associated hamiltonian structures for which compact expressions are found. the fundamental poisson brackets yield q - deformations of w _ { kp } and related w - type algebras which, in specific cases, coincide with the ones constructed by frenkel and reshetikhin. the construction underlies a continuous correspondence between the hamiltonian structures of the toda lattice and the kp hierarchies.
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arxiv:q-alg/9512025
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we give a simple demonstration of the formula relating the glass transition temperature, $ t _ g $, to the molar concentration $ x $ of a modifier in two types of glasses : binary glasses, whose composition can be denoted by $ x _ ny _ m + xm _ py _ q $, with ^ $ x $ an element of iii - rd or iv - th group ( e. g. b, or si, ge ), while $ m _ py _ q $ is an alkali oxide or chalcogenide ; next, the network glasses of the type $ a _ xb _ { 1 - x } $, e. g. $ ge _ xse _ { 1 - x } $, $ si _ xte _ { 1 - x } $, etc. after comparison, this formula gives an exact expression of the parameter $ \ beta $ of the modified gibbs - di marzio equation.
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arxiv:cond-mat/9809245
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let $ m $ and $ k \ geq 2 $ be positive integers. we show that polynomial $ p = ( 1 + x ) ^ m ( 1 + x ^ k ) $ is strongly unimodal ( frequently known as { \ it log concave \ / } ) if and only if $ m \ geq k ^ 2 - 3 $ ; this is also the criterion for $ p $ to be merely unimodal ( that is, for $ p $ of this form, unimodality implies strong unimodality ). { } in section 2, we investigate an analogous question, concerning the property $ \ ee $ of functions $ f $ analytic on a neighbourhood of the unit circle [ h2 ], and show that the corresponding minimal $ m $ is rather surprisingly of order $ k ^ 4 $.
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arxiv:1102.2961
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the multi - photon excitation to the $ 8 $ - ev nuclear isomeric state $ ^ { 229 \ text { m } } $ th in the direct laser - nucleus interaction is investigated theoretically. we solve the time - dependent schr \ " odinger equation with the method which allows us to study the $ n $ - photon absorption in the nuclear excitation in the direct laser - nucleus interaction. based on the laser facilities available currently or in the near future, we analyze the impact of the laser parameters on the excitation probability of the multi - photon excitation. the possibilities of the $ 2 $ -, $ 3 $ - and $ 4 $ - photon excitations to the isomeric state $ ^ { 229 \ text { m } } $ th from the ground state are discussed in details. our results show the strong impact of the laser intensity and pulse duration on the multi - photon excitation probability. the onset of high - order effects in the multi - photon excitation in the direct laser - nucleus interaction is also revealed. our findings open new possibilities to study the multi - photon laser - nucleus interaction in high - power laser facilities.
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arxiv:2504.18828
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a discussion of the quantum mechanical use of superposition or entangled states shows that descriptions containing only statements about state vectors and experiments outputs are the most suitable for quantum mechanics. in particular, it is shown that statements about the undefined values of physical quantities before measurement can be dropped without changing the predictions of the theory. if we apply these ideas to epr issues, we find that the concept of non - locality with its ' instantaneous action at a distance ' evaporates. finally, it is argued that usual treatments of philosophical realist positions end up in the construction of theories whose major role is that of being disproved by experiment. this confutation proves simply that the theories are wrong ; no conclusion about realism ( or any other philosophical position ) can be drawn, since experiments deal always with theories and these are never logical consequences of philosophical positions.
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arxiv:quant-ph/0507028
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for the very first time, the correlation femtoscopy method is applied to a kinematically complete measurement of meson production in the collisions of hadrons. a two - proton correlation function was derived from the data for the pp - > ppx reaction, measured near the threshold of eta meson production. a technique developed for the purpose of this analysis permitted to establish the correlation function separately for the production of the pp + eta and of the pp + pions systems. the shape of the two - proton correlation function for the ppeta differs from that for the pp ( pions ) and both do not show a peak structure opposite to results determined for inclusive measurements of heavy ion collisions.
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arxiv:1003.4377
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we wholeheartedly congratulate drs. rohe and zeng for their insightful paper \ cite { rohe2020vintage } on vintage factor analysis with varimax rotation. this note discusses the conditions to guarantee varimax consistently recovers the subspace rotation.
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arxiv:2205.10151
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classical control noise is ubiquitous in qubit devices, making its accurate spectral characterization essential for designing optimized error suppression strategies at the physical level. here, we focus on multiplicative gaussian amplitude control noise on a driven qubit sensor and show that sensing protocols using optimally band - limited slepian modulation offer substantial benefit in realistic scenarios. special emphasis is given to laying out the theoretical framework necessary for extending non - parametric multitaper spectral estimation to the quantum setting by highlighting key points of contact and differences with respect to the classical formulation. in particular, we introduce and analyze two approaches ( adaptive vs. single - setting ) to quantum multitaper estimation, and show how they provide a practical means to both identify fine spectral features not otherwise detectable by existing protocols and to obtain reliable prior estimates for use in subsequent parametric estimation, including high - resolution bayesian techniques. we quantitatively characterize the performance of both single - and multitaper slepian estimation protocols by numerically reconstructing representative spectral densities, and demonstrate their advantage over dynamical - decoupling noise spectroscopy approaches in reducing bias from spectral leakage as well as in compensating for aliasing effects while maintaining a desired sampling resolution.
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arxiv:1803.05538
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we present joint x - ray and optical observations of the high redshift ( z ~ 0. 83 ) lensing cluster clj0152. 7 - 1357 made with the chandra x - ray observatory and the keck telescope. we confirm the existence of significant substructure at both x - ray and optical wavelengths in the form of two distinct clumps, whose temperatures are 6. 6 ( - 1. 5, + 2. 4 ) kev and 5. 7 ( - 1. 6, + 2. 9 ) kev, respectively. the x - ray surface brightness profiles of the two clumps can be fitted by either a single beta - model or an nfw - like profile ; the latter giving better fits to the central regions. we find that the x - ray derived mass of this cluster is in good agreement with independent lensing measurements. while its appearance indicates that the cluster has not reached a dynamical equilibrium state, its x - ray luminosity l _ x, temperature t and dynamical mass m are consistent with the well - defined l _ x - t and m - t relations for low - redshift galaxy clusters, which suggests that the dynamical properties of the clusters have remained almost unchanged since z ~ 0. 8.
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arxiv:astro-ph/0312186
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we examine the effect of circumstellar dust extinction on the near - ir contribution of asymptotic giant branch ( agb ) stars in intermediate - age clusters throughout the disk of m100. for our sample of 17 agb - dominated clusters we extract optical - to - mid - ir seds and find that nir brightness is coupled to the mid - ir dust emission in such a way that a significant reduction of agb light, of up to 1 mag in k - band, follows from extinction by the dust shell formed during this stage. since the dust optical depth varies with agb chemistry ( c - rich or o - rich ), our results suggest that the contribution of agb stars to the flux from their host clusters will be closely linked to the metallicity and the progenitor mass of the agb star, to which dust chemistry and mass - loss rate are sensitive. our sample of clusters - - each the analogue of a ~ 1 gyr old post - starburst galaxy - - has implications within the context of mass and age estimation via sed modelling at high z : we find that the average ~ 0. 5 mag extinction estimated here may be sufficient to reduce the agb contribution in ( rest - frame ) k - band from ~ 70 %, as predicted in the latest generation of synthesis models, to ~ 35 %. our technique for selecting agb - dominated clusters in nearby galaxies promises to be effective for discriminating the uncertainties associated with agb stars in intermediate - age populations that plague age and mass estimation in high - z galaxies.
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arxiv:1203.0467
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we have investigated the behavior of the resistance of graphene at the $ n = 0 $ landau level in an intense magnetic field $ h $. employing a low - dissipation technique ( with power $ p < $ 3 fw ), we find that, at low temperature $ t $, the resistance at the dirac point $ r _ 0 ( h ) $ undergoes a 1000 - fold increase from $ \ sim $ 10 k $ \ omega $ to 40 m $ \ omega $ within a narrow interval of field. the abruptness of the increase suggests that a transition to an insulating, ordered state occurs at the critical field $ h _ c $. results from 5 samples show that $ h _ c $ depends systematically on the disorder, as measured by the offset gate voltage $ v _ 0 $. samples with small $ v _ 0 $ display a smaller critical field $ h _ c $. empirically, the steep increase in $ r _ 0 $ fits acccurately a kosterlitz - thouless - type correlation length over 3 decades. the curves of $ r _ 0 $ vs. $ t $ at fixed $ h $ approach the thermal - activation form with a gap $ \ delta \ sim $ 15 k as $ h \ to h _ c ^ { - } $, consistent with a field - induced insulating state.
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arxiv:0808.0906
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for each $ m \ ge 1 $ and $ p > 2 $ we characterize bounded simply connected sobolev $ l ^ m _ p $ - extension domains $ \ omega \ subset r ^ 2 $. our criterion is expressed in terms of certain intrinsic subhyperbolic metrics in $ \ omega $. its proof is based on a series of results related to the existence of special chains of squares joining given points $ x $ and $ y $ in $ \ omega $. an important geometrical ingredient for obtaining these results is a new " square separation theorem ". it states that under certain natural assumptions on the relative positions of a point $ x $ and a square $ s \ subset \ omega $ there exists a similar square $ q \ subset \ omega $ which touches $ s $ and has the property that $ x $ and $ s $ belong to distinct connected components of $ \ omega \ setminus q $.
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arxiv:1410.3100
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context : the mass - metallicity relationship ( mmr ) of star - forming galaxies is well - established, however there is still some disagreement with respect to its exact shape and its possible dependence on other observables. aims : we measure the mmr in the galaxy and mass assembly ( gama ) survey. we compare our measured mmr to that measured in the sloan digital sky survey ( sdss ) and study the dependence of the mmr on various selection criteria to identify potential causes for disparities seen in the literature. methods : we use strong emission line ratio diagnostics to derive oxygen abundances. we then apply a range of selection criteria for the minimum signal - to - noise in various emission lines, as well as the apparent and absolute magnitude to study variations in the inferred mmr. results : the shape and position of the mmr can differ significantly depending on the metallicity calibration and selection used. after selecting a robust metallicity calibration amongst those tested, we find that the mass - metallicity relation for redshifts 0. 061 < z < 0. 35 in gama is in reasonable agreement with that found in the sdss despite the difference in the luminosity range probed. conclusions : in view of the significant variations of the mmr brought about by reasonable changes in the sample selection criteria and method, we recommend that care be taken when comparing the mmr from different surveys and studies directly. we also conclude that there could be a modest level of evolution over 0. 06 < z < 0. 35 within the gama sample.
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arxiv:1209.1636
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the cellular adaptive immune response plays a key role in resolving influenza infection. experiments where individuals are successively infected with different strains within a short timeframe provide insight into the underlying viral dynamics and the role of a cross - reactive immune response in resolving an acute infection. we construct a mathematical model of within - host influenza viral dynamics including three possible factors which determine the strength of the cross - reactive cellular adaptive immune response : the initial naive t cell number, the avidity of the interaction between t cells and the epitopes presented by infected cells, and the epitope abundance per infected cell. our model explains the experimentally observed shortening of a second infection when cross - reactivity is present, and shows that memory in the cellular adaptive immune response is necessary to protect against a second infection.
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arxiv:1606.00495
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in this study, we investigate how the central nervous system ( cns ) organizes postural control synergies when individuals perform a complex catch - and - throw task in a virtual reality ( vr ) environment. a robotic upright stand trainer ( robust ) platform, including surface electromyography and kinematics, was used to investigate how the cns fine - tunes postural synergies with perturbative and assist - as - needed force fields. a control group without assistive forces was recruited to elucidate the effect of force fields on motor performance and postural synergy organization after the perturbation and during the vr reaching task. we found that the application of assistive forces significantly improved reaching and balance control. the group receiving assistive forces displayed four postural control synergies characterized by higher complexity ( i. e., greater number of muscles involved ). however, control subjects displayed eight synergies that recruited less number of muscles. in conclusion, assistive forces reduce the number of postural synergies while increasing the complexity of muscle module composition.
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arxiv:2208.09009
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photometric follow - ups of transiting exoplanets may lead to discoveries of additional, less massive bodies in extrasolar systems. this is possible by detecting and then analysing variations in transit timing of transiting exoplanets. we present photometric observations gathered in 2009 and 2010 for exoplanet wasp - 3b during the dedicated transit - timing - variation campaign. the observed transit timing cannot be explained by a constant period but by a periodic variation in the observations minus calculations diagram. simplified models assuming the existence of a perturbing planet in the system and reproducing the observed variations of timing residuals were identified by three - body simulations. we found that the configuration with the hypothetical second planet of the mass of about 15 earth masses, located close to the outer 2 : 1 mean motion resonance is the most likely scenario reproducing observed transit timing. we emphasize, however, that more observations are required to constrain better the parameters of the hypothetical second planet in wasp - 3 system. for final interpretation not only transit timing but also photometric observations of the transit of the predicted second planet and the high precision radial - velocity data are needed.
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arxiv:1006.1348
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low earth orbit ( leo ) satellites present a compelling opportunity for the establishment of a global quantum information network. however, satellite - based entanglement distribution from a networking perspective has not been fully investigated. existing works often do not account for satellite movement over time when distributing entanglement and / or often do not permit entanglement distribution along inter - satellite links, which are two shortcomings we address in this paper. we first define a system model which considers both satellite movement over time and inter - satellite links. we next formulate the optimal entanglement distribution ( oed ) problem under this system model and show how to convert the oed problem in a dynamic physical network to one in a static logical graph which can be used to solve the oed problem in the dynamic physical network. we then propose a polynomial time greedy algorithm for computing satellite - assisted multi - hop entanglement paths. we also design an integer linear programming ( ilp ) - based algorithm to compute optimal solutions as a baseline to study the performance of our greedy algorithm. we present evaluation results to demonstrate the advantage of our model and algorithms.
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arxiv:2306.08894
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the presence of a central baryonic potential can have a significant impact on the gravothermal evolution of self - interacting dark matter ( sidm ) haloes. we extend a semi - analytical fluid model to incorporate the influence of a static baryonic potential and calibrate it using controlled n - body simulations. we construct benchmark scenarios with varying baryon concentrations and different sidm models, including constant and velocity - dependent self - interacting cross sections. the presence of the baryonic potential induces changes in sidm halo properties, including central density, core size, and velocity dispersion, and it accelerates the halo ' s evolution in both expansion and collapse phases. furthermore, we observe a quasi - universality in the gravothermal evolution of sidm haloes with the baryonic potential, resembling a previously known feature in the absence of the baryons. by appropriately rescaling the physical quantities that characterize the sidm haloes, the evolution of all our benchmark cases exhibits remarkable similarity. our findings offer a framework for testing sidm predictions using observations of galactic systems where baryons play a significant dynamical role.
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arxiv:2306.08028
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topological insulator ( ti ) states have been demonstrated in materials with narrow gap and large spin - orbit interactions ( soi ). here we demonstrate that nanoscale engineering can also give rise to a ti state, even in conventional semiconductors with sizable gap and small soi. based on advanced first - principles calculations combined with an effective low - energy k * p hamiltonian, we show that the intrinsic polarization of materials can be utilized to simultaneously reduce the energy gap and enhance the soi, driving the system to a ti state. the proposed system consists of ultrathin inn layers embedded into gan, a layer structure that is experimentally achievable.
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arxiv:1205.2912
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$ \ text { la } _ 2 \ text { ni } _ 7 $ is an itinerant magnet with a small saturated moment of $ \ sim $ 0. 1 $ \ mu _ { b } / \ text { ni } $ and a series of antiferromagnetic ( afm ) transitions at $ t _ 1 $ = 61. 0 k, $ t _ 2 $ = 56. 5 k and $ t _ 3 $ = 42. 2 k. temperature and field dependent measurements suggest a complex, anisotropic $ h - t $ phase diagram with multiple phase lines. here we present the growth and characterization of single crystals of the $ { \ text { la } _ { 2 } \ text { ( cu } _ { x } \ text { ni } _ { 1 - x } ) _ 7 } $ series for 0 $ \ leq x \ leq $ 0. 181. using a suite of anisotropic magnetic, transport, and thermodynamic measurements we study the evolution of the three afm transitions upon cu substitution. for $ { 0 \ leq x \ leq 0. 097 } $, the system remains magnetically ordered at base temperature with $ x \ leq $ 0. 012, showing signs of three primarily afm phases. for the higher substitution levels, $ { 0. 125 \ leq x \ leq 0. 181 } $, there are no signatures of magnetic ordering, but an anomalous feature in resistance and heat capacity data are observed which are consistent with the kondo effect in this system. the intermediate $ x $ = 0. 105 sample lies in between the magnetic ordered and the kondo regime and is in the vicinity of the afm - quantum critical point ( qcp ). thus, $ { \ text { la } _ { 2 } \ text { ( cu } _ { x } \ text { ni } _ { 1 - x } ) _ 7 } $ is an example of a small moment system that can be tuned through a qcp. given these data combined with the fact that the $ \ text { la } _ 2 \ text { ni } _ 7 $ structure has kagome - like, ni - sublattice running perpendicular to the crystallographic $ c - $ axis, and a $ 3d $ - electron flat band that contributes to the density of states near the fermi energy, it becomes a promising candidate to host and study exotic physics.
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arxiv:2503.11872
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the inference of ying et al. [ epl 104, 67005 ( 2013 ) ] of a composition - induced change from c - axis ordered - moment alignment in a collinear a - type antiferromagnetic ( afm ) structure ( afmi ) at small x to ab - plane alignment in an unknown afm structure ( afmii ) at larger x in ca ( 1 - x ) sr ( x ) co ( 2 - y ) as ( 2 ) with the body - centered tetragonal thcr2si2 structure is confirmed. our major finding is an anomalous magnetic behavior in the crossover region 0. 2 < x < 0. 3 between these two phases. in this region the magnetic susceptibility versus temperature chi _ ab ( t ) measured with magnetic fields h applied in the ab plane exhibit typical afm behaviors with cusps at the neel temperatures of about 65 k, whereas chi _ c ( t ) and the low - temperature isothermal magnetization m _ c ( h ) with h aligned along the c axis exhibit extremely soft ferromagnetic - like behaviors.
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arxiv:1711.03547
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we consider parallel asynchronous markov chain monte carlo ( mcmc ) sampling for problems where we can leverage ( stochastic ) gradients to define continuous dynamics which explore the target distribution. we outline a solution strategy for this setting based on stochastic gradient hamiltonian monte carlo sampling ( sghmc ) which we alter to include an elastic coupling term that ties together multiple mcmc instances. the proposed strategy turns inherently sequential hmc algorithms into asynchronous parallel versions. first experiments empirically show that the resulting parallel sampler significantly speeds up exploration of the target distribution, when compared to standard sghmc, and is less prone to the harmful effects of stale gradients than a naive parallelization approach.
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arxiv:1612.00767
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compressed sensing ( cs ) is an effective approach to reduce the required number of samples for reconstructing a sparse signal in an a priori basis, but may suffer severely from the issue of basis mismatch. in this paper we study the problem of simultaneously recovering multiple spectrally - sparse signals that are supported on the same frequencies lying arbitrarily on the unit circle. we propose an atomic norm minimization problem, which can be regarded as a continuous counterpart of the discrete cs formulation and be solved efficiently via semidefinite programming. through numerical experiments, we show that the number of samples per signal may be further reduced by harnessing the joint sparsity pattern of multiple signals.
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arxiv:1311.2229
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semiconductors with very low lattice thermal conductivities are highly desired for applications relevant to thermal energy conversion and management, such as thermoelectrics and thermal barrier coatings. although the crystal structure and chemical bonding are known to play vital roles in shaping heat transfer behavior, material design approaches of lowering lattice thermal conductivity using chemical bonding principles are uncommon. in this work, we present an effective strategy of weakening interatomic interactions and therefore suppressing lattice thermal conductivity based on chemical bonding principles and develop a high - efficiency approach of discovering low $ \ kappa _ { \ rm l } $ materials by screening the local coordination environments of crystalline compounds. the followed first - principles calculations uncover 30 hitherto unexplored compounds with ( ultra ) low lattice thermal conductivities from thirteen prototype crystal structures contained in the inorganic crystal structure database. furthermore, we demonstrate an approach of rationally designing high - performance thermoelectrics by additionally incorporating cations with stereochemically active lone - pair electrons. our results not only provide fundamental insights into the physical origin of the low lattice thermal conductivity in a large family of copper - based compounds but also offer an efficient approach to discovery and design materials with targeted thermal transport properties.
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arxiv:2107.04955
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we study the properties of the google matrix of an ulam network generated by intermittency maps. this network is created by the ulam method which gives a matrix approximant for the perron - frobenius operator of dynamical map. the spectral properties of eigenvalues and eigenvectors of this matrix are analyzed. we show that the pagerank of the system is characterized by a power law decay with the exponent $ \ beta $ dependent on map parameters and the google damping factor $ \ alpha $. under certain conditions the pagerank is completely delocalized so that the google search in such a situation becomes inefficient.
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arxiv:0911.3823
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in general, small bodies of the solar system, e. g., asteroids and comets, have a very irregular shape. this feature affects significantly the gravitational potential around these irregular bodies, which hinders dynamical studies. the poincar \ ' e surface of sec - tion technique is often used to look for stable and chaotic regions in two - dimensional dynamic cases. in this work, we show that this tool can be useful for exploring the surroundings of irregular bodies such as the asteroid 4179 toutatis. considering a rotating system with a particle, under the effect of the gravitational field computed three - dimensionally, we define a plane in the phase space to build the poincar \ ' e surface of sections. despite the extra dimension, the sections created allow us to find trajec - tories and classify their stabilities. thus, we have also been able to map stable and chaotic regions, as well as to find correlations between those regions and the contri - bution of the third dimension of the system to the trajectory dynamics as well. as examples, we show details of periodic ( resonant or not ) and quasi - periodic trajectories.
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arxiv:1711.06506
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the ^ 18f ( p, alpha ) ^ 15o reaction is recognized as one of the most important reaction for nova gamma - ray astronomy as it governs the early = < 511 kev emission. however, its rate remains largely uncertain at nova temperatures due to unknown low - energy resonance strengths. in order to better constrain this reaction rate, we have studied the one - nucleon transfer reaction, d ( ^ 18f, p alpha ) ^ 15n, at the crc - rib facility at louvain la neuve.
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arxiv:nucl-ex/0209017
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the subdivision graph $ \ mathcal { s } ( g ) $ of a graph $ g $ is the graph obtained by inserting a new vertex into every edge of $ g $. let $ g _ 1 $ and $ g _ 2 $ be two vertex disjoint graphs. the \ emph { subdivision - vertex join } of $ g _ 1 $ and $ g _ 2 $, denoted by $ g _ 1 \ dot { \ vee } g _ 2 $, is the graph obtained from $ \ mathcal { s } ( g _ 1 ) $ and $ g _ 2 $ by joining every vertex of $ v ( g _ 1 ) $ with every vertex of $ v ( g _ 2 ) $. the \ emph { subdivision - edge join } of $ g _ 1 $ and $ g _ 2 $, denoted by $ g _ 1 \ underline { \ vee } g _ 2 $, is the graph obtained from $ \ mathcal { s } ( g _ 1 ) $ and $ g _ 2 $ by joining every vertex of $ i ( g _ 1 ) $ with every vertex of $ v ( g _ 2 ) $, where $ i ( g _ 1 ) $ is the set of inserted vertices of $ \ mathcal { s } ( g _ 1 ) $. in this paper we determine the adjacency spectra, the laplacian spectra and the signless laplacian spectra of $ g _ 1 \ dot { \ vee } g _ 2 $ ( respectively, $ g _ 1 \ underline { \ vee } g _ 2 $ ) for a regular graph $ g _ 1 $ and an arbitrary graph $ g _ 2 $, in terms of the corresponding spectra of $ g _ 1 $ and $ g _ 2 $. as applications, these results enable us to construct infinitely many pairs of cospectral graphs. we also give the number of the spanning trees and the kirchhoff index of $ g _ 1 \ dot { \ vee } g _ 2 $ ( respectively, $ g _ 1 \ underline { \ vee } g _ 2 $ ) for a regular graph $ g _ 1 $ and an arbitrary graph $ g _ 2 $.
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arxiv:1212.0619
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we present the analysis of seven \ emph { chandra } high energy transmission grating spectrometer and six simultaneous \ emph { rxte } proportional counter array observations of the persistent neutron star ( ns ) low - mass x - ray binary gx 13 + 1 on its normal and horizontal branches. across nearly 10 years, gx 13 + 1 is consistently found to be accreting at $ 50 - 70 $ \ % eddington, and all observations exhibit multiple narrow, blueshifted absorption features, the signature of a disk wind, despite the association of normal and horizontal branches with jet activity. a single absorber with standard abundances cannot account for all seven major disk wind features, indicating that multiple absorption zones may be present. two or three absorbers can produce all of the absorption features at their observed broadened widths and reveal that multiple kinematic components produce the accretion disk wind signature. assuming the most ionized absorber reflects the physical conditions closest to the ns, we estimate a wind launching radius of $ 7 \ times10 ^ { 10 } $ cm, for an electron density of $ 10 ^ { 12 } $ cm $ ^ { - 3 } $. this is consistent with the compton radius and also with a thermally driven wind. because of the source ' s high eddington fraction, radiation pressure likely facilitates the wind launching.
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arxiv:1806.08800
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just as spontaneous symmetry breaking can be understood in terms of energy, emergent symmetry ( more precisely, its ` size ' and structure ) can also be explained by free energy. in particular, in renormalization group flow to rational conformal field theory, we find infrared symmetry category is realized by consistent modular tensor category with minimal free energy. for demonstration, we study non - unitary theories.
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arxiv:2207.10095
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in this work we perform a general study of properties of a class of locally symmetric embedded hypersurfaces in spacetimes admitting a $ 1 + 1 + 2 $ spacetime decomposition. the hypersurfaces are given by specifying the form of the ricci tensor with respect to the induced metric. these are slices of constant time in the spacetime. firstly, the form of the ricci tensor for general hypersurfaces is obtained and the conditions under which the general case reduces to those of constant time slices are specified. we provide a characterization of these hypersurfaces, with key physical quantities in the spacetime playing a role in specifying the local geometry of these hypersurfaces. furthermore, we investigate the case where these hypersurfaces admit a ricci soliton structure. the particular cases where the vector fields associated to the solitons are killing or conformal killing vector fields are analyzed. finally, in the context of spacetimes with local rotational symmetry it is shown that, only spacetimes in this class with vanishing rotation and spatial twist can admit the hypersurface types considered, and that the hypersurfaces are necessarily flat. and if such hypersurface do admit a ricci soliton structure, the soliton is steady, with the components of the soliton field being constants.
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arxiv:2112.03219
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the lockheed f - 117 nighthawk, and the unstealthy fairchild republic a - 10 thunderbolt ii. to achieve infrared stealth, the exhaust gas is cooled to the temperatures where the brightest wavelengths it radiates are absorbed by atmospheric carbon dioxide and water vapor, greatly reducing the infrared visibility of the exhaust plume. another way to reduce the exhaust temperature is to circulate coolant fluids such as fuel inside the exhaust pipe, where the fuel tanks serve as heat sinks cooled by the flow of air along the wings. ground combat includes the use of both active and passive infrared sensors. thus, the united states marine corps ( usmc ) ground combat uniform requirements document specifies infrared reflective quality standards. = = reducing radio frequency ( rf ) emissions = = in addition to reducing infrared and acoustic emissions, a stealth vehicle must avoid radiating any other detectable energy, such as from onboard radars, communications systems, or rf leakage from electronics enclosures. the f - 117 uses passive infrared and low light level television sensor systems to aim its weapons and the f - 22 raptor has an advanced lpi radar which can illuminate enemy aircraft without triggering a radar warning receiver response. = = measuring = = the size of a target ' s image on radar is measured by the rcs, often represented by the symbol σ and expressed in square meters. this does not equal geometric area. a perfectly conducting sphere of projected cross sectional area 1 m2 ( i. e. a diameter of 1. 13 m ) will have an rcs of 1 m2. note that for radar wavelengths much less than the diameter of the sphere, rcs is independent of frequency. conversely, a square flat plate of area 1 m2 will have an rcs of σ = 4π a2 / λ2 ( where a = area, λ = wavelength ), or 13, 982 m2 at 10 ghz if the radar is perpendicular to the flat surface. at off - normal incident angles, energy is reflected away from the receiver, reducing the rcs. modern stealth aircraft are said to have an rcs comparable with small birds or large insects, though this varies widely depending on aircraft and radar. if the rcs was directly related to the target ' s cross - sectional area, the only way to reduce it would be to make the physical profile smaller. rather, by reflecting much of the radiation away or by absorbing it, the target achieves a smaller radar cross section. = = tactics = = stealthy strike aircraft such as the lockheed f - 117 nighthawk, are usually used
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https://en.wikipedia.org/wiki/Stealth_technology
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inspired by the superior language abilities of large language models ( llm ), large vision - language models ( lvlm ) have been recently explored by integrating powerful llms for improving the performance on complex multimodal tasks. despite the promising progress on lvlms, we find that lvlms suffer from the hallucination problem, i. e. they tend to generate objects that are inconsistent with the target images in the descriptions. to investigate it, this work presents the first systematic study on object hallucination of lvlms. we conduct the evaluation experiments on several representative lvlms, and show that they mostly suffer from severe object hallucination issue. we further discuss that the visual instructions may influence the hallucination, and find that : objects that frequently occur in the visual instructions or co - occur with the image objects, are obviously prone to be hallucinated by lvlms. besides, we find that existing evaluation methods might be affected by the input instructions and generation styles of lvlms. thus, we further design an improved evaluation method for object hallucination by proposing a polling - based query method called pope. experiment results demonstrate that our pope can evaluate the object hallucination in a more stable and flexible way. our codes and data are publicly available at https : / / github. com / rucaibox / pope.
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arxiv:2305.10355
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tendon - driven continuum robots ( tdcrs ) are promising candidates for applications in confined spaces due to their unique shape, compliance, and miniaturization capability. non - parallel tendon routing for tdcrs have shown definite advantages including segments with higher degrees of freedom, larger workspace and higher dexterity. however, most works have focused on parallel tendons to achieve constant - curvature shapes, which yields analytically simple kinematics but overly restricts the design possibilities. we believe this under - utilization of general tendon routing can be attributed to the lack of a general kinematic model that estimates shape from only tendon geometry and displacements. cosserat rod - based models are capable of modeling general tendon routing, but they require accurate tendon tension measurements and extensive system identification, hindering their usability for design purposes. recent attempts in developing a kinematic model are limited to simple scenarios like actuation with a single tendon or tendons on perpendicular planes. moreover, model formulations are often disconnected from hardware, making designs challenging to build under manufacturing constraints. our first contribution is a novel design for tdcrs based on a synovial universal joint module, which provides a mechanically discretized and feasible design space. based on the design, our second contribution is the formulation and evaluation of an optimization - based kinematic model, capable of handling actuation of multiple general routed tendons. lastly, we present an example application of a tdcr designed for gaited locomotion, demonstrating our method ' s potential for an unified model - based design pipeline.
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arxiv:2409.13165
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the problems in our teaching on object - oriented programming are analyzed, and the basic ideas, causes and methods of the reform are discussed on the curriculum, theoretical teaching and practical classes. our practice shows that these reforms can improve students ' understanding of object - oriented to enhance students ' practical ability and innovative ability.
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arxiv:2502.04596
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free actions of finite groups on spheres give rise to topological spherical space forms. the existence and classification problems for space forms have a long history in the geometry and topology of manifolds. in this article, we present a survey of some of the main results and a guide to the literature.
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arxiv:1412.8187
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a model of a finite cylindrical ion channel through a phospholipid membrane of width $ l $ separating two electrolyte reservoirs is studied. analytical solution of the poisson equation is obtained for an arbitrary distribution of ions inside the trans - membrane pore. the solution is asymptotically exact in the limit of large ionic strength of electrolyte on the two sides of membrane. however, even for physiological concentrations of electrolyte, the electrostatic barrier sizes found using the theory are in excellent agreement with the numerical solution of the poisson equation. the analytical solution is used to calculate the electrostatic potential energy profiles for pores containing charged protein residues. availability of a semi - exact interionic potential should greatly facilitate the study of ionic transport through nanopores and ion channels.
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arxiv:cond-mat/0604099
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we introduce an approach for imposing physically informed inductive biases in learned simulation models. we combine graph networks with a differentiable ordinary differential equation integrator as a mechanism for predicting future states, and a hamiltonian as an internal representation. we find that our approach outperforms baselines without these biases in terms of predictive accuracy, energy accuracy, and zero - shot generalization to time - step sizes and integrator orders not experienced during training. this advances the state - of - the - art of learned simulation, and in principle is applicable beyond physical domains.
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arxiv:1909.12790
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semantic overlap summarization ( sos ) is a constrained multi - document summarization task, where the constraint is to capture the common / overlapping information between two alternative narratives. while recent advancements in large language models ( llms ) have achieved superior performance in numerous summarization tasks, a benchmarking study of the sos task using llms is yet to be performed. as llms ' responses are sensitive to slight variations in prompt design, a major challenge in conducting such a benchmarking study is to systematically explore a variety of prompts before drawing a reliable conclusion. fortunately, very recently, the teler taxonomy has been proposed which can be used to design and explore various prompts for llms. using this teler taxonomy and 15 popular llms, this paper comprehensively evaluates llms on the sos task, assessing their ability to summarize overlapping information from multiple alternative narratives. for evaluation, we report well - established metrics like rouge, bertscore, and sem - f1 $ on two different datasets of alternative narratives. we conclude the paper by analyzing the strengths and limitations of various llms in terms of their capabilities in capturing overlapping information the code and datasets used to conduct this study are available at https : / / anonymous. 4open. science / r / llm _ eval - e16d.
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arxiv:2402.17008
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we use the recently proposed scattering states numerical renormalization group ( snrg ) approach to calculate $ i ( v ) $ and the differential conductance through a single molecular level coupled to a local molecular phonon. we also discuss the equilibrium physics of the model and demonstrate that the low - energy hamiltonian is given by an effective interacting resonant level model. from the nrg level flow, we directly extract the effective charge transfer scale $ \ gamma _ { \ rm eff } $ and the dynamically induced capacitive coupling $ u _ { \ rm eff } $ between the molecular level and the lead electrons which turns out to be proportional to the polaronic energy shift $ e _ p $ for the regimes investigated here. the equilibrium spectral functions for the different parameter regimes are discussed. the additional phonon peaks at multiples of the phonon frequency $ \ w _ 0 $ correspond to additional maxima in the differential conductance. non - equilibrium effects, however, lead to significant deviations between a symmetric junction and a junction in the tunnel regime. the suppression of the current for asymmetric junctions with increasing electron - phonon coupling, the hallmark of the franck - condon blockade, is discussed with a simple framework of a combination of ( i ) polaronic level shifts and ( ii ) the effective charge transfer scale $ \ gamma _ { \ rm eff } $.
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arxiv:1302.0184
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we present a theoretical study of minimum error probability discrimination, using quantum - optical probe states, of m optical phase shifts situated symmetrically on the unit circle. we assume ideal lossless conditions and full freedom for implementing quantum measurements and for probe state selection, subject only to a constraint on the average energy, i. e., photon number. in particular, the probe state is allowed to have any number of signal and ancillary modes, and to be pure or mixed. our results are based on a simple criterion that partitions the set of pure probe states into equivalence classes with the same error probability performance. under an energy constraint, we find the explicit form of the state that minimizes the error probability. this state is an unentangled but nonclassical single - mode state. the error performance of the optimal state is compared with several standard states in quantum optics. we also show that discrimination with zero error is possible only beyond a threshold energy of ( m - 1 ) / 2. for the m = 2 case, we show that the optimum performance is readily demonstrable with current technology. while transmission loss and detector inefficiencies lead to a nonzero erasure probability, the error rate conditional on no erasure is shown to remain the same as the optimal lossless error rate.
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arxiv:1206.0673
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in order to understand the source and extent of the greater - than - classical information processing power of quantum systems, one wants to characterize both classical and quantum mechanics as points in a broader space of possible theories. one approach to doing this, pioneered by abramsky and coecke, is to abstract the essential categorical features of classical and quantum mechanics that support various information - theoretic constraints and possibilities, e. g., the impossibility of cloning in the latter, and the possibility of teleportation in both. another approach, pursued by the authors and various collaborators, is to begin with a very conservative, and in a sense very concrete, generalization of classical probability theory - - which is still sufficient to encompass quantum theory - - and to ask which " quantum " informational phenomena can be reproduced in this much looser setting. in this paper, we review the progress to date in this second programme, and offer some suggestions as to how to link it with the categorical semantics for quantum processes developed by abramsky and coecke.
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arxiv:0908.2352
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we report on the observation of suppression and revival of coherent backscattering of ultra - cold atoms launched in an optical disorder and submitted to a short dephasing pulse, as proposed in a recent paper of t. micklitz \ textit { et al. } [ arxiv : 1406. 6915 ]. this observation, in a quasi - 2d geometry, demonstrates a novel and general method to study weak localization by manipulating time reversal symmetry in disordered systems. in future experiments, this scheme could be extended to investigate higher order localization processes at the heart of anderson ( strong ) localization.
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arxiv:1411.1671
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in recent years, we have witnessed the proliferation of large amounts of online content generated directly by users with virtually no form of external control, leading to the possible spread of misinformation. the search for effective solutions to this problem is still ongoing, and covers different areas of application, from opinion spam to fake news detection. a more recently investigated scenario, despite the serious risks that incurring disinformation could entail, is that of the online dissemination of health information. early approaches in this area focused primarily on user - based studies applied to web page content. more recently, automated approaches have been developed for both web pages and social media content, particularly with the advent of the covid - 19 pandemic. these approaches are primarily based on handcrafted features extracted from online content in association with machine learning. in this scenario, we focus on web page content, where there is still room for research to study structural -, content - and context - based features to assess the credibility of web pages. therefore, this work aims to study the effectiveness of such features in association with a deep learning model, starting from an embedded representation of web pages that has been recently proposed in the context of phishing web page detection, i. e., web2vec.
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arxiv:2407.07914
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we present ngc 6221 as a case study of ` ` x - ray loud composite galaxies, ' ' which appear similar to starbursts at optical wavelengths and resemble traditional active galactic nuclei in x - rays. the net optical spectrum of ngc 6221 is properly characterized as a starburst galaxy, but in x - rays, ngc 6221 is similar to seyfert 1 galaxies, exhibiting a power - law continuum spectrum, a broad fe k alpha line, and continuum variability on timescales of days and years. high - resolution images reveal that the detected active nucleus is relatively weak, not only at optical, but also at near - infrared wavelengths. an obscuring starburst, in which the interstellar gas and dust associated with the starburst conceal the active nucleus, accounts for these peculiar features. we demonstrate quantitatively that obscuration by column density n _ h = 10 ^ { 22 } cm ^ { - 2 } combined with relatively weak intrinsic nuclear activity can produce an optical spectrum characteristic of the surrounding starburst alone. while optical surveys would not identify the active nuclei that make these galaxies significant x - ray sources, such galaxies may in fact be important contributors to the x - ray background.
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arxiv:astro-ph/0104316
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the renormalization group method in $ r ^ 2 $ - gravity without matter fields is discussed. a criterion for the existence of the renormalization constant for the metric has been found, two - loop higher order poles have been calculated, a relation which allows us to find the one - loop renormalization constant of the newtonian constant has been suggested.
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arxiv:hep-ph/9806252
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we investigate a laser model for a resonant system of photons and ion cluster - solvated rotating water molecules in which ions in the cluster are identical and have very low, non - relativistic velocities and direction of motion parallel to a static electric field induced in a single direction. this model combines dicke superradiation with wave - particle interaction. as the result, we find that the equations of motion of the system are expressed in terms of a conventional free electron laser system. this result leads to a mechanism for dynamical coherence, induced by collective instability in the wave - particle interaction.
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arxiv:1610.06219
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