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we construct calibrated submanifolds of r ^ 7 and r ^ 8 by viewing them as total spaces of vector bundles and taking appropriate sub - bundles which are naturally defined using certain surfaces in r ^ 4. we construct examples of associative and coassociative submanifolds of r ^ 7 and of cayley submanifolds of r ^ 8. this construction is a generalization of the harvey - lawson bundle construction of special lagrangian submanifolds of r ^ { 2n }. | arxiv:math/0408005 |
the correlation functions of two - dimensional anyon fields in a kms - state are studied. for t = 0 the $ n $ - particle wave functions of noncanonical fermions of level $ \ alpha $, $ \ alpha $ odd, are shown to be of laughlin type of order $ \ alpha $. for $ t > 0 $ they are given by a simple finite - temperature generalization of laughlin ' s wave function. this relates the first and second quantized pictures of the fractional quantum hall effect. | arxiv:hep-th/0010030 |
photons carrying orbital angular momentum ( oam ) are excellent qudits and are widely used in several applications, such as long distance quantum communication, $ d $ - dimensional teleportation and high - resolution imaging and metrology. all these protocols rely on quantum tomography to characterise the oam state, which currently requires complex measurements involving spatial light modulators and mode filters. to simplify the measurement and characterisation of oam states, here we apply a recent tomography protocol [ asadian et al., \ pra { \ bf 94 }, 010301 ( 2016 ) ]. our scheme for oam tomography in $ d $ dimensions requires only a set of measurements on a mode qubit, i. e., a 2 - dimensional system. this replaces the current complexity of oam measurements by the ability to perform generalized pauli operators $ x _ d, z _ d $ on oam states. our scheme can be adapted in principle to other degrees of freedom, thus opening the way for more complex qudit tomography. | arxiv:2003.08668 |
bethe ansatz equations for spin - $ s $ heisenberg spin chain with $ s \ ge1 $ are significantly more difficult to analyze than the spin - $ \ tfrac { 1 } { 2 } $ case, due to the presence of repeated roots. as a result, it is challenging to derive extra conditions for the bethe roots to be physical and study the related completeness problem. in this paper, we propose the rational $ q $ - system for the xxx $ _ s $ spin chain. solutions of the proposed $ q $ - system give all and only physical solutions of the bethe ansatz equations required by completeness. this is checked numerically and proved rigorously. the rational $ q $ - system is equivalent to the requirement that the solution and the corresponding dual solution of the $ tq $ - relation are both polynomials, which we prove rigorously. based on this analysis, we propose the extra conditions for solutions of the xxx $ _ s $ bethe ansatz equations to be physical. | arxiv:2303.07640 |
the aim of this paper is to find the necessary and sufficient conditions and inclusion relations for pascal distribution series to be in the classes sp _ { p } ( { \ alpha }, \ b { eta } ) and ucv _ { p } ( { \ alpha }, \ b { eta } ) of uniformly spirallike functions. further, we consider properties of a special function related to pascal distribution series. several corollaries and consequences of the main results are also considered. | arxiv:2001.07517 |
this white paper responds to the voyage 2050 call for white papers from the science programme of the european space agency ( esa ) and argues that education, communication and public engagement ( hereafter epe ) should have priority in the voyage 2050 planning cycle. the esa science ' s voyage 2050 missions promise insights into the big existential questions of our era : the prevalence of life in the universe ; the nature of space and time ; and the intertwined nature of matter, energy and gravity. it is likely that innovations in the acquisition, handling and processing of vast data sets will drive these themes to scientific maturity in the next decades. they offer us a timely opportunity to underline the relevance of space sciences to everyday life and thinking. more generally, space science is maturing to the point where it contributes to every major aspect of our cultural discourse. citizens need information, resources and opportunities to actively participate in that discourse, and esa science can provide these. this white paper is a modest attempt to support esa science improve its engagement with society. it focuses on issues and topics to improve esa science ' s education and public engagement activities. it does not dwell on the topics that esa already excels at ; hence this white paper provides a critical review of what should and could be improved. we believe esa ' s voyage 2050 programme teams have a responsibility to represent europe ' s social and cultural diversity, and our suggestions are conceived in that spirit : to support esa science ' s complex task of engaging a hugely diverse audience in the complex issues of planning, building and operating fascinating space missions. | arxiv:1908.01546 |
decoding stimuli or behaviour from recorded neural activity is a common approach to interrogate brain function in research, and an essential part of brain - computer and brain - machine interfaces. reliable decoding even from small neural populations is possible because high dimensional neural population activity typically occupies low dimensional manifolds that are discoverable with suitable latent variable models. over time however, drifts in activity of individual neurons and instabilities in neural recording devices can be substantial, making stable decoding over days and weeks impractical. while this drift cannot be predicted on an individual neuron level, population level variations over consecutive recording sessions such as differing sets of neurons and varying permutations of consistent neurons in recorded data may be learnable when the underlying manifold is stable over time. classification of consistent versus unfamiliar neurons across sessions and accounting for deviations in the order of consistent recording neurons in recording datasets over sessions of recordings may then maintain decoding performance. in this work we show that self - supervised training of a deep neural network can be used to compensate for this inter - session variability. as a result, a sequential autoencoding model can maintain state - of - the - art behaviour decoding performance for completely unseen recording sessions several days into the future. our approach only requires a single recording session for training the model, and is a step towards reliable, recalibration - free brain computer interfaces. | arxiv:2205.09829 |
identifying a low - dimensional informed parameter subspace offers a viable path to alleviating the dimensionality challenge in the sampled - based solution to large - scale bayesian inverse problems. this paper introduces a novel gradient - based dimension reduction method in which the informed subspace does not depend on the data. this permits an online - offline computational strategy where the expensive low - dimensional structure of the problem is detected in an offline phase, meaning before observing the data. this strategy is particularly relevant for multiple inversion problems as the same informed subspace can be reused. the proposed approach allows controlling the approximation error ( in expectation over the data ) of the posterior distribution. we also present sampling strategies that exploit the informed subspace to draw efficiently samples from the exact posterior distribution. the method is successfully illustrated on two numerical examples : a pde - based inverse problem with a gaussian process prior and a tomography problem with poisson data and a besov - $ \ mathcal { b } ^ 2 _ { 11 } $ prior. | arxiv:2102.13245 |
the tau - > mu nu nu branching ratio has been measured using data collected from 1990 to 1995 by the opal detector at the lep collider. the resulting value of b ( tau - > mu nu nu ) = 0. 1734 + / - 0. 0009 ( stat ) + / - 0. 0005 ( syst ) has been used in conjunction with other opal measurements to test lepton universality, yielding the coupling constant ratios g ( mu ) / g ( e ) = 1. 0005 + / - 0. 0043 and g ( tau ) / g ( e ) = 1. 0031 + / - 0. 0047, in good agreement with the standard model prediction of unity, and also to determine a value for the michel parameter eta = 0. 004 + / - 0. 036. this is subsequently used to find a model - dependent limit of the mass for the charged higgs boson, m ( higgs ) > 1. 30 tan ( beta ), in the minimal supersymmetric standard model. | arxiv:hep-ex/0209045 |
causal and counterfactual reasoning are emerging directions in data science that allow us to reason about hypothetical scenarios. this is particularly useful in fields like environmental and ecological sciences, where interventional data are usually not available. structural causal models are probabilistic models for causal analysis that simplify this kind of reasoning due to their graphical representation. they can be regarded as extensions of the so - called bayesian networks, a well known modeling tool commonly used in environmental and ecological problems. the main contribution of this paper is to analyze the relations of necessity and sufficiency between the variables of a socioecological system using counterfactual reasoning with bayesian networks. in particular, we consider a case study involving socioeconomic factors and land - uses in southern spain. in addition, this paper aims to be a coherent overview of the fundamental concepts for applying counterfactual reasoning, so that environmental researchers with a background in bayesian networks can easily take advantage of the structural causal model formalism. | arxiv:2401.10101 |
this paper presents data from the bima interferometer showing spatially resolved absorption spectra of the gravitationally lensed quasar pks 1830 - 211. high - resolution ( 1. 2 km / s ) spectra were taken in two spectral windows centered on the redshifted frequencies of the hco + ( 2 - 1 ) and hcn ( 2 - 1 ) molecular transitions. there is no molecular absorption in the northeast image but the southwest image reveals optically thick absorbing gas at these transition frequencies. further analyses conclude that the spectra are consistent with completely saturated absorption in the southwest image and the line profiles suggest that the absorbing medium is complex, perhaps containing multiple components and small scale structure. the absorption occurs along a pencil beam through the lensing galaxy which is thought to be a late type spiral oriented almost face on. however, the spectra show absorption spanning more than 60 km / s which is difficult to explain for this scenario. | arxiv:astro-ph/0102310 |
recent advances in test - time scaling have shown promising results in improving large language models ( llms ) performance through strategic computation allocation during inference. while this approach has demonstrated strong performance improvements in logical and mathematical reasoning tasks, its application to natural language generation ( nlg ), especially summarization, has yet to be explored. multi - document summarization ( mds ) is a challenging task that focuses on extracting and synthesizing useful information from multiple lengthy documents. unlike reasoning tasks, mds requires a more nuanced approach to prompt design and ensemble, as there is no " best " prompt to satisfy diverse summarization requirements. to address this, we propose a novel framework that leverages inference - time scaling for this task. precisely, we take prompt ensemble approach by leveraging various prompt to first generate candidate summaries and then ensemble them with an aggregator to produce a refined summary. we also introduce two new evaluation metrics : consistency - aware preference ( cap ) score and llm atom - content - unit ( acu ) score, to enhance llm ' s contextual understanding while mitigating its positional bias. extensive experiments demonstrate the effectiveness of our approach in improving summary quality while identifying and analyzing the scaling boundaries in summarization tasks. | arxiv:2502.20592 |
cardbus, and pc card. as of 2010, most newer laptop computers come equipped with built - in internal adapters. = = = router = = = wireless routers integrate a wireless access point, ethernet switch, and internal router firmware application that provides ip routing, nat, and dns forwarding through an integrated wan - interface. a wireless router allows wired and wireless ethernet lan devices to connect to a ( usually ) single wan device such as a cable modem, dsl modem, or optical modem. a wireless router allows all three devices, mainly the access point and router, to be configured through one central utility. this utility is usually an integrated web server that is accessible to wired and wireless lan clients and often optionally to wan clients. this utility may also be an application that is run on a computer, as is the case with as apple ' s airport, which is managed with the airport utility on macos and ios. = = = bridge = = = wireless network bridges can act to connect two networks to form a single network at the data - link layer over wi - fi. the main standard is the wireless distribution system ( wds ). wireless bridging can connect a wired network to a wireless network. a bridge differs from an access point : an access point typically connects wireless devices to one wired network. two wireless bridge devices may be used to connect two wired networks over a wireless link, useful in situations where a wired connection may be unavailable, such as between two separate homes or for devices that have no wireless networking capability ( but have wired networking capability ), such as consumer entertainment devices ; alternatively, a wireless bridge can be used to enable a device that supports a wired connection to operate at a wireless networking standard that is faster than supported by the wireless network connectivity feature ( external dongle or inbuilt ) supported by the device ( e. g., enabling wireless - n speeds ( up to the maximum supported speed on the wired ethernet port on both the bridge and connected devices including the wireless access point ) for a device that only supports wireless - g ). a dual - band wireless bridge can also be used to enable 5 ghz wireless network operation on a device that only supports 2. 4 ghz wireless and has a wired ethernet port. = = = repeater = = = wireless range - extenders or wireless repeaters can extend the range of an existing wireless network. strategically placed range - extenders can elongate a signal area or allow for the signal area to reach | https://en.wikipedia.org/wiki/Wi-Fi |
the ' rigid unit mode ' ( rum ) model requires unit blocks, in our case tetrahedra of sio _ 4 groups, to be rigid within first order of the displacements of the o - ions. the wave - vectors of the lattice vibrations, which obey this rigidity, are determined analytically. lattices with inversion symmetry yield generically surfaces of rums in reciprocal space, whereas lattices without this symmetry yield generically lines of rums. only in exceptional cases as in beta - quartz a surface of rums appears, if inversion symmetry is lacking. the occurence of planes and bending surfaces, straight and bent lines is discussed. explicit calculations are performed for five modifications of sio _ 2 crystals. | arxiv:cond-mat/0703486 |
an original optical tweezers using one or two chemically etched fiber nano - tips is developed. we demonstrate optical trapping of 1 micrometer polystyrene spheres at optical powers down to 2 mw. harmonic trap potentials were found in the case of dual fiber tweezers by analyzing the trapped particle position fluctuations. the trap stiffness was deduced using three different models. consistent values of up to 1 fn / nm were found. the stiffness linearly decreases with decreasing light intensity and increasing fiber tip - to - tip distance. | arxiv:1312.1850 |
levitation of optical scatterers provides a new mean to develop free - space volumetric displays. the principle is to illuminate a levitating particle displaced at high velocity in three dimensions ( 3d ) to create images based on persistence of vision ( pov ). light scattered by the particle can be observed all around the volumetric display and therefore provides a true 3d image that does not rely on interference effects and remains insensitive to the angle of observation. the challenge is to control with a high accuracy and at high speed the trajectory of the particle in three dimensions. systems that use light to generate free - space images either in plasma or with a bead are strictly dependent of the scanning method used. mechanical systems are required to scan the particles in the volume which weakens the time dynamics. here we use electrically driven planar paul traps ( ppts ) to control the trajectory of electrically charged particles. a single gold particle colloid is manipulated in three dimensions through ac and dc electrical voltages applied to a ppt. electric voltages can be modulated at high frequencies ( 150 khz ) and allow for a high speed displacement of particles without moving any other system component. the optical scattering of the particle in levitation yields free - space images that are imaged with conventional optics. the trajectory of the particle is entirely encoded in the electric voltage and driven through stationary planar electrodes. we show in this paper, the proof - of - concept for the generation of 3d free space graphics with a single electrically scanned particle. | arxiv:1806.06662 |
in this paper, we establish a bijection between the infinite reduced words of an affine weyl group and certain biclosed sets of its positive system and determine all finitely generated biclosed sets in the positive system of an affine weyl group. using these results, we show first that the biclosed sets in the standard positive system of rank 3 affine weyl groups when ordered by inclusion form a complete algebraic ortholattice and secondly that the ( generalized ) braid graphs of those coxeter groups are connected, which can be thought of as an infinite version of tit ' s solution to the word problem. | arxiv:1803.03017 |
water in contact with mineral interfaces is important for a variety of different processes. here, we present a combined theoretical - experimental study which provides a quantitative, molecular - level understanding of the ubiquitous and important flourite - water interface. our results show that, at low ph, the surface is positively charged, causing a substantial degree of water ordering. the surface charge originates primarily from the dissolution of fluoride ions, rather than from adsorption of protons to the surface. at high ph we observe the presence of ca - oh species pointing into the water. these oh groups interact remarkably weakly with the surrounding water, and are responsible for the free oh signature in the sfg spectrum, which can be explained from local electronic structure effects. the quantification of the surface termination, near - surface ion distribution and water arrangement is enabled by a combination of advanced phase - resolved vibrational sum frequency generation spectra of flourite - water interfaces and state - of - the - art ab initio molecular dynamics simulations which include electronic structure effects. | arxiv:1608.02825 |
excitonic spectra of armchair graphene nanoribbons ( agnrs ) obtained from a full many - body exact diagonalization of the hubbard model are reported for both longitudinally and transversely polarized photons, thus providing a complete survey of low - energy may - body optical excitations in these systems. the resulting one - photon allowed eigenstates turn out to be well separated in energy from each other but both couple to the same set of two - photon allowed states. the magnitude of the calculated optical oscillator strengths for perpendicular polarization suggest that these optical features can be indeed observed in polarized absorption measurements. | arxiv:1207.3268 |
this paper measures social media activity of 15 broad scientific disciplines indexed in scopus database using altmetric. com data. first, the presence of altmetric. com data in scopus database is investigated, overall and across disciplines. second, the correlation between the bibliometric and altmetric indices is examined using spearman correlation. third, a zero - truncated negative binomial model is used to determine the association of various factors with increasing or decreasing citations. lastly, the effectiveness of altmetric indices to identify publications with high citation impact is comprehensively evaluated by deploying area under the curve ( auc ) - an application of receiver operating characteristic. results indicate a rapid increase in the presence of altmetric. com data in scopus database from 10. 19 % in 2011 to 20. 46 % in 2015. a zero - truncated negative binomial model is implemented to measure the extent to which different bibliometric and altmetric factors contribute to citation counts. blog count appears to be the most important factor increasing the number of citations by 38. 6 % in the field of health professions and nursing, followed by twitter count increasing the number of citations by 8 % in the field of physics and astronomy. interestingly, both blog count and twitter count always show positive increase in the number of citations across all fields. while there was a positive weak correlation between bibliometric and altmetric indices, the results show that altmetric indices can be a good indicator to discriminate highly cited publications, with an encouragingly auc = 0. 725 between highly cited publications and total altmetric count. overall, findings suggest that altmetrics could better distinguish highly cited publications. | arxiv:1705.03258 |
we study the influence of a background uniform magnetic field and boundary conditions on the vacuum of a quantized charged massive scalar matter field confined between two parallel plates ; the magnetic field is directed orthogonally to the plates. the admissible set of boundary conditions at the plates is determined by the requirements that the operator of one - particle energy squared be self - adjoint and positive definite. we show that, in the case of a weak magnetic field and a small separation of the plates, the casimir force is either attractive or repulsive, depending on the choice of a boundary condition. in the case of a strong magnetic field and a large separation of the plates, the casimir force is repulsive, being independent of the choice of a boundary condition, as well as of the distance between the plates. | arxiv:1401.6950 |
following the work on shannon entropy together with the principle of maximum entropy, luo & singh ( j. hydrol. eng., 2011, 16 ( 4 ) : 303 - 315 ) and singh & luo ( j. hydrol. eng., 2011, 16 ( 9 ) : 725 - 735 ) explored the concept of non - extensive tsallis entropy for modelling velocity in open channels. later, the idea was extended by cui & singh ( j. hydrol. eng., 2013, 18 ( 3 ) : 331 - 339 ; 2014, 19 ( 2 ) : 290 - 298 ) by hypothesizing an accurate cumulative distribution function ( cdf ). however, these studies estimated the entropy index through a data - fitting procedure and the values of the index were different for different studies. the present study investigates the role of tsallis entropy index for modelling velocity in open channels using the method of moments, based on conservation of mass and momentum. it is found that the entropy index depends on the normalized mean velocity and the momentum coefficient. in addition to the physical meaning of the index, it is also found that the modified velocity profile significantly improves for both wide and narrow channels, as shown by small predicted velocity errors. the proposed approach may be further employed for other open channel flow problems, such as sediment concentration, and shear stress distribution. | arxiv:1910.11665 |
visual place recognition needs to be robust against appearance variability due to natural and man - made causes. training data collection should thus be an ongoing process to allow continuous appearance changes to be recorded. however, this creates an unboundedly - growing database that poses time and memory scalability challenges for place recognition methods. to tackle the scalability issue for visual place recognition in autonomous driving, we develop a hidden markov model approach with a two - tiered memory management. our algorithm, dubbed hm $ ^ 4 $, exploits temporal look - ahead to transfer promising candidate images between passive storage and active memory when needed. the inference process takes into account both promising images and a coarse representations of the full database. we show that this allows constant time and space inference for a fixed coverage area. the coarse representations can also be updated incrementally to absorb new data. to further reduce the memory requirements, we derive a compact image representation inspired by locality sensitive hashing ( lsh ). through experiments on real world data, we demonstrate the excellent scalability and accuracy of the approach under appearance changes and provide comparisons against state - of - the - art techniques. | arxiv:2011.00450 |
we consider an assortment optimization problem where a customer chooses a single item from a sequence of sets shown to her, while limited inventories constrain the items offered to customers over time. in the special case where all of the assortments have size one, our problem captures the online stochastic matching with timeouts problem. for this problem, we derive a polynomial - time approximation algorithm which earns at least 1 - ln ( 2 - 1 / e ), or 0. 51, of the optimum. this improves upon the previous - best approximation ratio of 0. 46, and furthermore, we show that it is tight. for the general assortment problem, we establish the first constant - factor approximation ratio of 0. 09 for the case that different types of customers value items differently, and an approximation ratio of 0. 15 for the case that different customers value each item the same. our algorithms are based on rounding an lp relaxation for multi - stage assortment optimization, and improve upon previous randomized rounding schemes to derive the tight ratio of 1 - ln ( 2 - 1 / e ). | arxiv:1908.09808 |
after a general introduction, the basic principles of wake - field and beamcoupling - impedance computations are explained. this includes time domain, frequency domain, and methods that do not include excitations by means of a particle beam. the second part of this paper deals with radio frequency bench measurements of beam coupling impedances. the general procedure of the wire measurement is explained, and its features and limitations are discussed. | arxiv:1805.01824 |
federated learning ( fl ) enables multiple users to collaboratively train a global model in a distributed manner without revealing their personal data. however, fl remains vulnerable to model poisoning attacks, where malicious actors inject crafted updates to compromise the global model ' s accuracy. these vulnerabilities are particularly severe in non - homogeneous environments, where clients exhibit varying proportions of class labels, resulting in heterogeneous updates. in such settings, benign outliers are often misclassified as false positives, while maliciously crafted uploads evade detection and are aggregated at the server. existing defense mechanisms struggle in such real - world settings, resulting in significant declines in the global fl model ' s performance. we propose a novel defense mechanism, kernel - based trust segmentation ( kets ), to counter model poisoning attacks. unlike existing approaches, kets analyzes the evolution of each client ' s updates and effectively segments malicious clients using kernel density estimation ( kde ), even in the presence of benign outliers. we thoroughly evaluate kets ' s performance against the six most effective model poisoning attacks ( i. e., trim - attack, krum - attack, min - max attack, min - sum attack, and their variants ) on two different datasets ( i. e., mnist and fashion - mnist ) and compare its performance with three classical robust schemes ( i. e., krum, trim - mean, and median ) and a state - of - the - art defense ( i. e., fltrust ). our results show that kets outperforms the existing defenses in every attack setting ; beating the best - performing defense by an overall average of > 24 % ( on mnist ) and > 14 % ( on fashion - mnist ). a series of further experiments ( varying poisoning approaches, attacker population, etc. ) reveal the consistent and superior performance of kets under diverse conditions. | arxiv:2501.06729 |
we determine the rational chow ring of the moduli space $ \ mathcal { h } _ { g, n } $ of $ n $ - pointed smooth hyperelliptic curves of genus $ g $ when $ n \ leq 2g + 6 $. we also show that the chow ring of the partial compactification $ \ mathcal { i } _ { g, n } $, parametrizing $ n $ - pointed irreducible nodal hyperelliptic curves, is generated by tautological divisors. along the way, we improve casnati ' s result that $ \ mathcal { h } _ { g, n } $ is rational for $ n \ leq 2g + 8 $ to show $ \ mathcal { h } _ { g, n } $ is rational for $ n \ leq 3g + 5 $. | arxiv:2207.10873 |
we consider type iib flux compactifications on six - dimensional su ( 2 ) - structure manifolds with o5 - and o7 - planes. these six - dimensional spaces allow not only for f _ 3 and h _ 3 fluxes but also for f _ 1 and f _ 5 fluxes. we derive the four - dimensional n = 1 scalar potential for such compactifications and present one explicit example of a fully stabilized ads vacuum with large volume and small string coupling. we then discuss cosmological aspects of these compactifications and derive several no - go theorems that forbid ds vacua and slow - roll inflation under certain conditions. we also study concrete examples of cosets and twisted tori and find that our no - go theorems forbid ds vacua and slow - roll inflation in all but one of them. for the latter we find a ds critical point with \ epsilon numerically zero. however, the point has two tachyons and eta - parameter \ eta \ approx - 3. 1. | arxiv:0912.3287 |
the origin of the erraticity behaviour observed recently in the experiment is studied in some detail. the negative - binomial distribution is used to fit the experimental multiplicity distribution. it is shown that, with the multiplicity distribution taken into account, the experimentally observed erraticity behaviour can be well reproduced using a flat probability distribution. the dependence of erraticity behaviour on the width of multiplicity distribution is studied. | arxiv:hep-ph/9907541 |
single - arm trials ( sats ) may be used to support regulatory submissions in settings where there is a high unmet medical need and highly promising early efficacy data undermine the equipoise needed for randomization. in this context, patient - level real - world data ( rwd ) may be used to create an external control arm ( eca ) to contextualize the sat results. however, naive comparisons of the sat with its eca will yield biased estimates of causal effects if groups are imbalanced with regards to ( un ) measured prognostic factors. several methods are available to adjust for measured confounding, but the interpretation of such analyses is challenging unless the causal question of interest is clearly defined, and the estimator is aligned with the estimand. additional complications arise when patients in the eca are eligible for the sat at multiple timepoints. in this paper, we use a case - study of a pivotal sat of a novel car - t therapy for heavily pre - treated patients with follicular lymphoma to illustrate how a combination of the target trial and the ich e9 ( r1 ) estimand frameworks can be used to define the target estimand and avoid common methodological pitfalls related to the design of the eca and comparisons with the sat. we also propose an approach to address the challenge of how to define an appropriate time zero for external controls who meet the sat inclusion / exclusion criteria at several timepoints. use of the target trial and estimand frameworks facilitates discussions amongst internal and external stakeholders, as well as an early assessment of the adequacy of the available rwd. | arxiv:2202.11968 |
with rapid advancements in exoskeleton hardware technologies, successful assessment and accurate control remain challenging. this study introduces a modular sensor - based system to enhance biomechanical evaluation and control in lower - limb exoskeletons, utilizing advanced sensor technologies and fuzzy logic. we aim to surpass the limitations of current biomechanical evaluation methods confined to laboratories and to address the high costs and complexity of exoskeleton control systems. the system integrates inertial measurement units, force - sensitive resistors, and load cells into instrumented crutches and 3d - printed insoles. these components function both independently and collectively to capture comprehensive biomechanical data, including the anteroposterior center of pressure and crutch ground reaction forces. this data is processed through a central unit using fuzzy logic algorithms for real - time gait phase estimation and exoskeleton control. validation experiments with three participants, benchmarked against gold - standard motion capture and force plate technologies, demonstrate our system ' s capability for reliable gait phase detection and precise biomechanical measurements. by offering our designs open - source and integrating cost - effective technologies, this study advances wearable robotics and promotes broader innovation and adoption in exoskeleton research. | arxiv:2409.01174 |
a numerical analysis of the effect of artificial viscosity is undertaken in order to understand the effect of numerical diffusion on numerical boundary feedback control. the analysis is undertaken on the linear hyperbolic systems discretised using the upwind scheme. the upwind scheme solves the advection - diffusion equation with up to second - order accuracy. the analysis shows that the upwind scheme with cfl equal to one gives the expected theoretical decay up to first - order. on the other hand the upwind scheme with cfl less than one gives decay depending on the second derivative of the data and the cfl number. further the decay rates deteriorate if the second derivatives of the solution are small. thus the decay rates computed by the numerical schemes tend to be higher in comparison to the theoretical prediction. computations on test cases which include isothermal euler and the st venant equations confirm the analytical results. | arxiv:2006.02484 |
low - noise lasers are of central importance in a wide variety of applications, including high spectral - efficiency coherent communication protocols, distributed fibre sensing, and long distance coherent lidar. in addition to low phase noise, frequency agility, that is, the ability to achieve high - bandwidth actuation of the laser frequency, is imperative for triangular chirping in frequency - modulated continuous - wave ( fmcw ) based ranging or any optical phase locking as routinely used in metrology. while integrated silicon - based lasers have experienced major advances and are now employed on a commercial scale in data centers, integrated lasers with sub - 100 hz - level intrinsic linewidth are based on optical feedback from photonic circuits that lack frequency agility. here, we demonstrate a wafer - scale - manufacturing - compatible hybrid photonic integrated laser that exhibits ultralow intrinsic linewidth of 25 hz while offering unsurpassed megahertz actuation bandwidth, with a tuning range larger than 1 ghz. our approach uses ultralow - loss ( 1 db / m ) si $ _ 3 $ n $ _ 4 $ photonic microresonators, combined with aluminium nitride ( aln ) or lead zirconium titanate ( pzt ) microelectromechanical systems ( mems ) based stress - optic actuation. electrically driven low - phase noise lasing is attained by self - injection locking of an indium phosphide ( inp ) laser chip and only limited by fundamental thermo - refractive noise. by utilizing difference drive and apodization of the photonic chip, a flat actuation response up to 10 mhz is achieved. we leverage this capability to demonstrate a compact coherent lidar engine that can generate up to 800 khz fmcw triangular optical chirp signals, requiring neither any active linearization nor predistortion compensation, and perform a 10 m optical ranging experiment, with a resolution of 12. 5 cm. | arxiv:2104.02990 |
in this paper we show how einstein metrics are naturally described using the quantization of the algebra of functions on a kahler manifold m. in this setup one interprets m as the phase space itself, equipped with the poisson brackets inherited from the kahler 2 - form. we compare the geometric quantization framework with several deformation quantization approaches. we find that the balanced metrics appear naturally as a result of setting the vacuum energy to be the constant function on the moduli space of semiclassical vacua. in the classical limit these metrics become kahler - einstein ( when m admits such metrics ). finally, we sketch several applications of this formalism, such as explicit constructions of special lagrangian submanifolds in compact calabi - yau manifolds. | arxiv:0710.1304 |
in the context of positioning a target with a single - anchor, this contribution focuses on the fisher information about the position, orientation and clock offset of the target provided by single - bounce reflections. the availability of prior knowledge of the target ' s environment is taken into account via a prior distribution of the position of virtual anchors, and the rank, intensity and direction of provided information is studied. we show that when no prior knowledge is available, single - bounce reflections offer position information in the direction parallel to the reflecting surface, irrespective of the target ' s and anchor ' s locations. we provide a geometrically intuitive explanation of the results and present numerical examples demonstrating their potential implications. | arxiv:2012.01597 |
we present a near - uv space telescope on a ~ 70kg micro - satellite with a moderately fast repointing capability and a near real - time alert communication system that has been proposed in response to a call for an ambitious czech national mission. the mission, which has recently been approved for phase 0, a, and b1 study shall measure the brightness evolution of kilonovae, resulting from mergers of neutron stars in the near - uv band and thus it shall distinguish between different explosion scenarios. between the observations of transient sources, the satellite shall perform observations of other targets of interest, a large part of which will be chosen in open competition. | arxiv:2207.05485 |
has been referred to as long tail learning. advocates of social learning claim that one of the best ways to learn something is to teach it to others. social networks have been used to foster online learning communities around subjects as diverse as test preparation and language education. mobile - assisted language learning ( mall ) is the use of handheld computers or cell phones to assist in language learning. collaborative apps allow students and teachers to interact while studying. apps are designed after games, which provide a fun way to revise. when the experience is enjoyable, the students become more engaged. games also usually come with a sense of progression, which can help keep students motivated and consistent while trying to improve. classroom 2. 0 refers to online multi - user virtual environments ( muves ) that connect schools across geographical frontiers. known as " etwinning ", computer - supported collaborative learning ( cscl ) allows learners in one school to communicate with learners in another that they would not get to know otherwise, enhancing educational outcomes and cultural integration. further, many researchers distinguish between collaborative and cooperative approaches to group learning. for example, roschelle and teasley ( 1995 ) argue that " cooperation is accomplished by the division of labor among participants, as an activity where each person is responsible for a portion of the problem solving ", in contrast with collaboration that involves the " mutual engagement of participants in a coordinated effort to solve the problem together. " social technology, and social media specifically, provides avenues for student learning that would not be available otherwise. for example, it provides ordinary students a chance to exist in the same room as, and share a dialogue with researchers, politicians, and activists. this is because it vaporizes the geographical barriers that would otherwise separate people. simplified, social media gives students a reach that provides them with opportunities and conversations that allow them to grow as communicators. social technologies like twitter can provide students with an archive of free data that goes back multiple decades. many classrooms and educators are already taking advantage of this free resource — for example, researchers and educators at the university of central florida in 2011 used tweets posted relating to emergencies like hurricane irene as data points, in order to teach their students how to code data. social media technologies also allow instructors the ability to show students how professional networks facilitate work on a technical level. = = = flipped classroom = = = this is an instructional strategy where the majority of the initial learning occurs first at home using technology. then, students will engage with higher - order learning tasks in the classroom with the teacher. often, | https://en.wikipedia.org/wiki/Educational_technology |
the bose - hubbard model is well - defined description of a bose solid which may be realistic for cold atoms in a periodic optical lattice. we show that contrary to accepted theories it can never have as a ground state a perfect mott insulator solid and that it has a low - energy spectrum of vortex - like phase fluctuations. whether the ground state is necessarily commensurate remains an open question. | arxiv:1102.4797 |
one alternative to the cold dark matter ( cdm ) paradigm is the scalar field dark matter ( sfdm ) model, which assumes dark matter is a spin - 0 ultra - light scalar field ( sf ) with a typical mass $ m \ sim10 ^ { - 22 } \ mathrm { ev } / c ^ 2 $ and positive self - interactions. due to the ultra - light boson mass, the sfdm could form bose - einstein condensates ( bec ) in the very early universe, which are interpreted as the dark matter haloes. although cosmologically the model behaves as cdm, they differ at small scales : sfdm naturally predicts fewer satellite haloes, cores in dwarf galaxies and the formation of massive galaxies at high redshifts. the ground state ( or bec ) solution at zero temperature suffices to describe low - mass galaxies but fails for larger systems. a possible solution is adding finite - temperature corrections to the sf potential which allows combinations of excited states. in this work, we test the finite - temperature multistate sfdm solution at galaxy cluster scales and compare our results with the navarro - frenk - white ( nfw ) and bec profiles. we achieve this by fitting the mass distribution of 13 \ textit { chandra } x - ray clusters of galaxies, excluding the region of the brightest cluster galaxy. we show that the sfdm model accurately describes the clusters ' dm mass distributions offering an equivalent or better agreement than the nfw profile. the complete disagreement of the bec model with the data is also shown. we conclude that the theoretically motivated multistate sfdm profile is an interesting alternative to empirical profiles and ad hoc fitting - functions that attempt to couple the asymptotic nfw decline with the inner core in sfdm. | arxiv:1609.08644 |
the notion of multipliers in hilbert space was introduced by schatten in 1960 using orthonormal sequences and was generalized by balazs in 2007 using bessel sequences. this was extended to banach spaces by rahimi and balazs in 2010 using p - bessel sequences. in this paper, we further extend this by considering lipschitz functions. on the way we define frames for metric spaces which extends the notion of frames and bessel sequences for banach spaces. we show that when the symbol sequence converges to zero, the multiplier is a lipschitz compact operator. we study how the variation of parameters in the multiplier effects the properties of multiplier. | arxiv:2007.03209 |
soon after the gaia data release ( dr ) 3 in june 2022, some candidates ( and one confirmed ) of detached black hole ( bh ) - luminous companion ( lc ) binaries have been reported. existing and future detections of astrometric bh - lc binaries will shed light on the spatial distribution of these systems, which can deepen our understanding of the natal kicks and the underlying formation mechanism of bhs. by tracking galactic orbits of bh - lc binaries obtained from bse, we find that distributions of bh mass and the height from the galactic plane | z | would help us give a constraint on supernova model. we also indicate that the correlations of ( i ) orbital periods and eccentricities, and ( ii ) bh mass and $ | z | $ could be clues for the strength of natal kick, and that the correlations of ( $ p $, $ z / z _ \ odot $ ) may tell us a clue for common envelope ( ce ) efficiency. we also discuss the possibility of forming bh - lc binaries like the bh binary candidates reported in gaia dr3 and gaia bh 1, finding that if the candidates as well as the confirmed binary originate from isolated binaries, they favor models which produce low - mass bhs and have high ce efficiencies exceeding unity. | arxiv:2301.07207 |
it is shown that single and double spin asymmetries in polarized diffractive $ q \ bar q $ production depend strongly on the spin structure of the quark - pomeron vertex. they can be studied in future spin experiments at hera. | arxiv:hep-ph/9510405 |
diffusion mri tractography is an important tool for identifying and analyzing the intracranial course of cranial nerves ( cns ). however, the complex environment of the skull base leads to ambiguous spatial correspondence between diffusion directions and fiber geometry, and existing diffusion tractography methods of cns identification are prone to producing erroneous trajectories and missing true positive connections. to overcome the above challenge, we propose a novel cns identification framework with anatomy - guided fiber trajectory distribution, which incorporates anatomical shape prior knowledge during the process of cns tracing to build diffusion tensor vector fields. we introduce higher - order streamline differential equations for continuous flow field representations to directly characterize the fiber trajectory distribution of cns from the tract - based level. the experimental results on the vivo hcp dataset and the clinical mdm dataset demonstrate that the proposed method reduces false - positive fiber production compared to competing methods and produces reconstructed cns ( i. e. cn ii, cn iii, cn v, and cn vii / viii ) that are judged to better correspond to the known anatomy. | arxiv:2402.18856 |
modern cosmic ray transport codes, that are capable of use for a variety of applications, need to include all significant atomic, nuclear and particle reactions at a variety of energies. lepton pair production from nucleus - nucleus collisions has not been included in transport codes to date. using the methods of baur, bertulani and baron, the present paper provides estimates of electron - positron pair production cross sections for nuclei and energies relevant to cosmic ray transport. it is shown that the cross sections are large compared to other typical processes such as single neutron removal due to strong or electromagnetic interactions. therefore lepton pair production may need to be included in some transport code applications involving mev electrons. | arxiv:nucl-th/0612054 |
standard maximum likelihood estimation cannot be applied to discrete energy - based models in the general case because the computation of exact model probabilities is intractable. recent research has seen the proposal of several new estimators designed specifically to overcome this intractability, but virtually nothing is known about their theoretical properties. in this paper, we present a generalized estimator that unifies many of the classical and recently proposed estimators. we use results from the standard asymptotic theory for m - estimators to derive a generic expression for the asymptotic covariance matrix of our generalized estimator. we apply these results to study the relative statistical efficiency of classical pseudolikelihood and the recently - proposed ratio matching estimator. | arxiv:1202.3746 |
large scale structures in the universe, ranging from globular clusters to entire galaxies, are the manifestation of relaxation to out - of - equilibrium states that are not described by standard statistical mechanics at equilibrium. instead, they are formed through a process of a very different nature, i. e. violent relaxation. however, astrophysical time - scales are so large that it is not possible to directly observe these relaxation dynamics and therefore verify the details of the violent relaxation process. we develop a table - top experiment and model that allows us to directly observe effects such as mixing of phase space, and violent relaxation, leading to the formation of a table - top analogue of a galaxy. the experiment allows us to control a range of parameters, including the nonlocal ( gravitational ) interaction strength and quantum effects, thus providing an effective test - bed for gravitational models that cannot otherwise be directly studied in experimental settings. | arxiv:2205.10948 |
as generalizations of results of christandl et al. \ cite { 8, 9 " " } and facer et al. \ cite { facer }, bernasconi et al. \ cite { godsil, godsil1 } studied perfect state transfer ( pst ) between two particles in quantum networks modeled by a large class of cubelike graphs ( e. g., the hypercube ) which are the cayley graphs of the elementary abelian group $ z _ 2 ^ n $. in refs. \ cite { pst, psd }, respectively, pst of a qubit over distance regular spin networks and optimal state transfer ( st ) of a $ d $ - level quantum state ( qudit ) over pseudo distance regular networks were discussed, where the networks considered there were not in general related with a certain finite group. in this paper, pst of a qudit over antipodes of more general networks called underlying networks of association schemes, is investigated. in particular, we consider the underlying networks of group association schemes in order to employ the group properties ( such as irreducible characters ) and use the algebraic structure of these networks ( such as bose - mesner algebra ) in order to give an explicit analytical formula for coupling constants in the hamiltonians so that the state of a particular qudit initially encoded on one site will perfectly evolve to the opposite site without any dynamical control. it is shown that the only necessary condition in order to pst over these networks be achieved is that the centers of the corresponding groups be non - trivial. therefore, pst over the underlying networks of the group association schemes over all the groups with non - trivial centers such as the abelian groups, the dihedral group $ d _ { 2n } $ with even $ n $, the clifford group cl ( n ) and all of the $ p $ - groups can be achieved. | arxiv:0901.4504 |
until recently many studies of bone remodeling at the cellular level have focused on the behavior of mature osteoblasts and osteoclasts, and their respective precursor cells, with the role of osteocytes and bone lining cells left largely unexplored. this is particularly true with respect to the mathematical modeling of bone remodeling. however, there is increasing evidence that osteocytes play important roles in the cycle of targeted bone remodeling, in serving as a significant source of rankl to support osteoclastogenesis, and in secreting the bone formation inhibitor sclerostin. moreover, there is also increasing interest in sclerostin, an osteocyte - secreted bone formation inhibitor, and its role in regulating local response to changes in the bone microenvironment. here we develop a cell population model of bone remodeling that includes the role of osteocytes, sclerostin, and allows for the possibility of rankl expression by osteocyte cell populations. this model extends and complements many of the existing mathematical models for bone remodeling but can be used to explore aspects of the process of bone remodeling that were previously beyond the scope of prior modeling work. through numerical simulations we demonstrate that our model can be used to theoretically explore many of the most recent experimental results for bone remodeling, and can be utilized to assess the effects of novel bone - targeting agents on the bone remodeling process. | arxiv:1211.6397 |
we prove that for the martinet wave equation with " flat " metric, which a subelliptic wave equation, singularities can propagate at any speed between 0 and 1 along any singular geodesic. this is in strong contrast with the usual propagation of singularities at speed 1 for wave equations with elliptic laplacian. | arxiv:2105.03305 |
the strong version of maldacena ' s ads / cft conjecture implies that the large n expansion of free n = 4 super - ym theory describes an interacting string theory in the extreme limit of high spacetime curvature relative to the string length. string states may then be understood as composed of sym string bits. we investigate part of the low - lying spectrum of the tensionless ( zero - coupling ) limit and find a large number of states that are not present in the infinite tension ( strong - coupling ) limit, notably several massless spin two particles. we observe that all conformal dimensions are n - independent in the free sym theory, implying that masses in the corresponding string theory are unchanged by string interactions. degenerate string states do however mix in the interacting string theory because of the complicated n - dependence of general cft two - point functions. finally we verify the cft crossing symmetry, which corresponds to the dual properties of string scattering amplitudes. this means that the sym operator correlation functions define ads dual models analogous to the minkowski dual models that gave rise to string theory. | arxiv:hep-th/0002189 |
damsa ( dark messenger searches at an accelerator ) experiment is a table - top scale, extremely - short - baseline experiment designed to probe dark - sector particles ( dsps ) that serve as portals between the visible sector and the hidden dark - matter sector. these particles, such as axion - like particles ( alps ), can decay into two photons or electron - positron pairs. damsa is specifically optimized to explore regions of parameter space that are inaccessible to past and current experiments, by operating at ultra - short baselines and employing high - resolution calorimetry, precision timing, and precision tracking in a magnetic field with suppression of beam - related neutron backgrounds. the experiment can be integrated into facilities, such as cern ' s beam - dump - facility ( bdf ), operating concurrently with the ship experiment, and provides complementary sensitivity in the mev to gev mass range. damsa represents a cost - effective and timely opportunity to expand cern ' s discovery potential in dark - sector physics. it exemplifies how innovative, small - scale experiments can effectively complement large - scale experiments, taking advantage of existing and future infrastructure. | arxiv:2504.02923 |
we parallelize density - matrix renormalization group to directly extend it to 2 - dimensional ( $ n $ - leg ) quantum lattice models. the parallelization is made mainly on the exact diagonalization for the superblock hamiltonian since the part requires an enormous memory space as the leg number $ n $ increases. the superblock hamiltonian is divided into three parts, and the correspondent superblock vector is transformed into a matrix, whose elements are uniformly distributed into processors. the parallel efficiency shows a high rate as the number of the states kept $ m $ increases, and the eigenvalue converges within only a few sweeps in contrast to the multichain algorithm. | arxiv:0707.0159 |
context. the populations of small bodies of the solar system ( asteroids, comets, kuiper - belt objects ) are used to constrain the origin and evolution of the solar system. both their orbital distribution and composition distribution are required to track the dynamical pathway from their regions of formation to their current locations. aims. we aim at increasing the sample of solar system objects that have multi - filter photometry and compositional taxonomy. methods. we search for moving objects in the archive of the sloan digital sky survey. we attempt at maximizing the number of detections by using loose constraints on the extraction. we then apply a suite of filters to remove false - positive detections ( stars or galaxies ) and mark out spurious photometry and astrometry. results. we release a catalog of 1 542 522 entries, consisting of 1 036 322 observations of 379 714 known and unique ssos together with 506 200 observations of moving sources not linked with any known ssos. the catalog completeness is estimated to be about 95 % and the purity to be above 95 % for known ssos. | arxiv:2108.05749 |
in this paper, we investigated structures and charge density waves, including its origin of cdw, by using first - principles calculations. firstly, we performed structure searches of nbse _ 2 under different pressures to explore the possible structures of the cdw phase in nbse _ 2. the stability of the resulted structure is proved by extensive studies of energy calculations and phonon spectra. based on the detailed analysis on electronic properties ( both in real space and k space ) and band structures during cdw transitions, we believe the structure distortion and the displacement of atoms are the origin of cdw, which also cause the change of the fermi surfaces and electronic density of states ( dos ). in the end, the results of band structure and dos were used to explain the reason why cdw and superconducting orders compete with each other at low temperature. | arxiv:1707.03318 |
we consider the possibility that the excess of cosmic rays near $ \ sim 10 ^ { 18 } $ ev, reported by the agasa and sugar groups from the direction of the galactic center, is caused by a young, very fast pulsar in the high density medium. the pulsar accelerates iron nuclei to energies $ \ sim 10 ^ { 20 } $ ev, as postulated by the galactic models for the origin of the highest energy cosmic rays. the iron nuclei, after about 1 yr since pulsar formation, leave the supernova envelope without energy losses and diffuse through the dense central region of the galaxy. some of them collide with the background matter creating neutrons ( from desintegration of fe ), neutrinos and gamma - rays ( in inelastic collisions ). wse suggest that neutrons produced at a specific time after the pulsar formation are responsible for the observed excess of cosmic rays at $ \ sim 10 ^ { 18 } $ ev. from normalization of the calculated neutron flux to the one observed in the cosmic ray excess, we predict the neutrino and gamma - ray fluxes. it has been found that the 1 km $ ^ 2 $ neutrino detector of the icecube type should detect from a few up to several events per year from the galactic center, depending on the parameters of the considered model. also future systems of cherenkov telescopes ( cangaroo iii, hess, veritas ) should be able to observe 1 - 10 tev $ \ gamma $ - rays from the galactic center if the pulsar was created inside a huge molecular cloud about $ 3 - 10 \ times 10 ^ 3 $ yrs ago. | arxiv:astro-ph/0112008 |
let $ g $ be a connected closed subgroup of $ \ mathrm { gl } _ n ( \ mathbb { c } ) $ which is simple as a lie group and which acts irreducibly on $ \ mathbb { c } ^ n $. regarding both $ g $ and its lie algebra $ \ mathfrak { g } $ as subsets of $ m _ n ( \ mathbb { c } ) $, we have $ g \ cap \ mathfrak { g } \ neq \ emptyset $ if and only if $ g $ is a classical group and $ \ mathbb { c } ^ n $ is a minuscule representation. | arxiv:2207.13209 |
in this note we prove that qr - submanifolds of the hyper - kahler manifolds under some conditions admit the $ g _ 2 $ holonomy. we give simplest examples of such qr - submanifolds namely tori. we conjecture that all $ g _ 2 $ holonomy manifolds arise in this way. | arxiv:1104.4895 |
stability of the zero solution plays an important role in the investigation of positive systems. in this note, we revisit the $ \ mu $ - stability of positive nonlinear systems with unbounded time - varying delays. the system is modelled by continuous - time differential equations. under some assumptions on the nonlinear functions like homogeneous, cooperative, nondecreasing, we propose a novel transform, by which the nonlinear system reduces to a new system. thus, we analyze its dynamics, which can simplify the nonlinear homogenous functions with respect to ( w. r. t. ) arbitrary dilation map to those w. r. t. the standard dilation map. we finally get some criteria for the global $ \ mu $ - stability. a numerical example is given to demonstrate the validity of obtained results. | arxiv:1505.07565 |
the order parameters of dynamical chiral symmetry breaking in qcd, the dynamical mass of quarks and the chiral condensates, are evaluated by numerically solving the non - perturbative renormalization group ( nprg ) equations. we employ an approximation scheme beyond ` ` the ladder ' ', that is, beyond the ( improved ) ladder schwinger - dyson equations. the chiral condensates are enhanced compared with the ladder ones, which is phenomenologically favorable. the gauge dependence of the order parameters is fairly reduced in this scheme. | arxiv:hep-th/0002038 |
community detection is a major issue in network analysis. this paper combines a socio - historical approach with an experimental reconstruction of programs to investigate the early automation of clique detection algorithms, which remains one of the unsolved np - complete problems today. the research led by the archaeologist jean - claude gardin from the 1950s on non - numerical information and graph analysis is retraced to demonstrate the early contributions of social sciences and humanities. the limited recognition and reception of gardin ' s innovative computer application to the humanities are addressed through two factors, in addition to the effects of historiography and bibliographies on the recording, discoverability, and reuse of scientific productions : 1 ) funding policies, evidenced by the transfer of research effort on graph applications from temporary interdisciplinary spaces to disciplinary organizations related to the then - emerging field of computer science ; and 2 ) the erratic careers of algorithms, in which efficiency, flaws, corrections, and authors ' status, were determining factors. | arxiv:2110.15567 |
we compute the $ v _ 1 $ - periodic $ \ mathbb { r } $ - motivic stable homotopy groups. the main tool is the effective slice spectral sequence. along the way, we also analyze $ \ mathbb { c } $ - motivic and $ \ eta $ - periodic $ v _ 1 $ - periodic homotopy from the same perspective. | arxiv:2204.05937 |
for high - redshift submillimetre or millimetre sources detected with single dish telescopes, interferometric follow - up has shown that many are multiple submm galaxies blended together. confusion - limited herschel observations of such targets are also available, and these sample the peak of their spectral energy distribution in the far - infrared. many methods for analysing these data have been adopted, but most follow the traditional approach of extracting fluxes before model spectral energy distributions are fit, which has the potential to erase important information on degeneracies among fitting parameters and glosses over the intricacies of confusion noise. here, we adapt the forward - modelling method that we originally developed to disentangle a high - redshift strongly - lensed galaxy group, in order to tackle this problem in a more statistically rigorous way, by combining source deblending and sed fitting into the same procedure. we call this method " sedeblend. " as an application, we derive constraints on far - infrared luminosities and dust temperatures for sources within the alma follow - up of the laboca extended chandra deep field south submillimetre survey. we find an average dust temperature for an 870 micron - selected sample of ( 33. 9 + - 2. 4 ) k for the full survey. when selection effects of the sample are considered, we find no evidence that the average dust temperature evolves with redshift. | arxiv:1512.04615 |
we give sufficient conditions for mosco convergences for the following three cases : symmetric locally uniformly elliptic diffusions, symmetric l \ ' evy processes, and symmetric jump processes in terms of the $ l ^ 1 ( \ mathbb r ; dx ) $ - local convergence of the ( elliptic ) coefficients, the characteristic exponents and the jump density functions, respectively. we stress that the global path properties of the corresponding markov processes such as recurrence / transience, and conservativeness / explosion are not preserved under mosco convergences and we give several examples where such situations indeed happen. | arxiv:1412.0725 |
the task of recognizing the age - separated faces of an individual, age - invariant face recognition ( aifr ), has received considerable research efforts in europe, america, and asia, compared to africa. thus, aifr research efforts have often under - represented / misrepresented the african ethnicity with non - indigenous africans. this work developed an aifr system for indigenous african faces to reduce the misrepresentation of african ethnicity in facial image analysis research. we adopted a pre - trained deep learning model ( vggface ) for aifr on a dataset of 5, 000 indigenous african faces ( fage \ _ v2 ) collected for this study. fage \ _ v2 was curated via internet image searches of 500 individuals evenly distributed across 10 african countries. vggface was trained on fage \ _ v2 to obtain the best accuracy of 81. 80 \ %. we also performed experiments on an african - american subset of the cacd dataset and obtained the best accuracy of 91. 5 \ %. the results show a significant difference in the recognition accuracies of indigenous versus non - indigenous africans. | arxiv:2408.06806 |
consider the continuum of points along the edges of a network, i. e., an undirected graph with positive edge weights. we measure distance between these points in terms of the shortest path distance along the network, known as the network distance. within this metric space, we study farthest points. we introduce network farthest - point diagrams, which capture how the farthest points - - - and the distance to them - - - change as we traverse the network. we preprocess a network g such that, when given a query point q on g, we can quickly determine the farthest point ( s ) from q in g as well as the farthest distance from q in g. furthermore, we introduce a data structure supporting queries for the parts of the network that are farther away from q than some threshold r > 0, where r is part of the query. we also introduce the minimum eccentricity feed - link problem defined as follows. given a network g with geometric edge weights and a point p that is not on g, connect p to a point q on g with a straight line segment pq, called a feed - link, such that the largest network distance from p to any point in the resulting network is minimized. we solve the minimum eccentricity feed - link problem using eccentricity diagrams. in addition, we provide a data structure for the query version, where the network g is fixed and a query consists of the point p. | arxiv:1304.1909 |
we investigate the possibility to realize the unification of the standard model gauge interactions at the low scale in four dimensions. we find that the fields needed to define a minimal theory where baryon and lepton numbers are local symmetries, allow for unification at the low scale in agreement with experiments. in these scenarios the proton is stable and we briefly discuss the implications for cosmology. | arxiv:1405.1199 |
high dimensional data for classification does create many difficulties for machine learning algorithms. the generalization can be done using ensemble learning methods such as bagging based supervised non - parametric random forest algorithm. in this paper we solve the problem of binary classification for high dimensional data using random forest for polycystic ovary syndrome dataset. we have performed the implementation and provided a detailed visualization of the data for general inference. the training accuracy that we have achieved is 95. 6 % and validation accuracy over 91. 74 % respectively. | arxiv:2202.07779 |
1959 ). fundamentals of engineering drawing for technical students and professional. m. a. parker, f. pickup ( 1990 ) engineering drawing with worked examples. colin h. simmons, dennis e. maguire manual of engineering drawing. elsevier. cecil howard jensen ( 2001 ). interpreting engineering drawings. b. leighton wellman ( 1948 ). technical descriptive geometry. mcgraw - hill book company, inc. = = external links = = examples of cubes drawn in different projections animated presentation of drawing systems used in technical drawing ( flash animation ) archived 2011 - 07 - 06 at the wayback machine design handbook : engineering drawing and sketching, by mit opencourseware | https://en.wikipedia.org/wiki/Engineering_drawing |
we report on wide - field imaging of pulsatile motion induced by blood flow using heterodyne holographic interferometry on the thumb of a healthy volunteer, in real - time. optical doppler images were measured with green laser light by a frequency - shifted mach - zehnder interferometer in off - axis configuration. the recorded optical signal was linked to local instantaneous out - of - plane motion of the skin at velocities of a few hundreds of microns per second, and compared to blood pulse monitored by plethysmoraphy during an occlusion - reperfusion experiment. | arxiv:1501.05776 |
using the data from the public database of the all sky automated survey ( { \ tt asas } ) we performed the very first light curve analyses of the three eclipsing binary systems \ astrobj { ao ~ aqr }, \ astrobj { cw ~ aqr } and \ astrobj { asas ~ 012206 - 4924. 7 }. the physical parameters of the systems were determined by the { \ tt phoebe } software. from an analysis of the asas data it was concluded that ao ~ aqr was found to be a contact binary system while cw ~ aqr and asas ~ 012206 - 4924. 7 were found to be near - - contact and detached binaries, respectively. finally, the locations of the components, corresponding to the estimated physical parameters, in the hr diagram were also discussed. | arxiv:1505.03648 |
while the linear pearson correlation coefficient represents a well - established normalized measure to quantify the interrelation of two stochastic variables $ x $ and $ y $, it fails for multidimensional variables such as cartesian coordinates. avoiding any assumption about the underlying data, the mutual information $ i ( x, y ) $ does account for multidimensional correlations. however, unlike the normalized pearson correlation, it has no upper bound ( $ i \ in [ 0, \ infty ) $ ), i. e., it is not clear if say, $ i = 0. 4 $ corresponds to a low or a high correlation. moreover, the mutual information ( mi ) involves the estimation of high - dimensional probability densities ( e. g., six - dimensional for cartesian coordinates ), which requires a k - nearest neighbor algorithm, such as the estimator by kraskov et al. [ phys. rev. e 69, 066138 ( 2004 ) ]. as existing methods to normalize the mi cannot be used in connection with this estimator, a new approach is presented, which uses an entropy estimation method that is invariant under variable transformations. the algorithm is numerically efficient and does not require more effort than the calculation of the ( un - normalized ) mi. after validating the method by applying it to various toy models, the normalized mi between the $ c _ { \ alpha } $ - coordinates of t4 lysozyme is considered and compared to a correlation analysis of inter - residue contacts. | arxiv:2405.04980 |
recommender systems trained in a continuous learning fashion are plagued by the feedback loop problem, also known as algorithmic bias. this causes a newly trained model to act greedily and favor items that have already been engaged by users. this behavior is particularly harmful in personalised ads recommendations, as it can also cause new campaigns to remain unexplored. exploration aims to address this limitation by providing new information about the environment, which encompasses user preference, and can lead to higher long - term reward. in this work, we formulate a display advertising recommender as a contextual bandit and implement exploration techniques that require sampling from the posterior distribution of click - through - rates in a computationally tractable manner. traditional large - scale deep learning models do not provide uncertainty estimates by default. we approximate these uncertainty measurements of the predictions by employing a bootstrapped model with multiple heads and dropout units. we benchmark a number of different models in an offline simulation environment using a publicly available dataset of user - ads engagements. we test our proposed deep bayesian bandits algorithm in the offline simulation and online ab setting with large - scale production traffic, where we demonstrate a positive gain of our exploration model. | arxiv:2008.00727 |
the rectangular collocation approach makes it possible to solve the schr \ " odinger equation with basis functions that do not have amplitude in all regions in which wavefunctions have significant amplitude. collocation points can be restricted to a small region of space. as no integrals are computed, there are no problems due to discontinuities in the potential, and there is no need to use integrable basis functions. in this paper, we show, for the kohn - sham equation, that machine learning can be used to drastically reduce the size of the collocation point set. this is demonstrated by solving the kohn - sham equations for co and h2o. we solve the kohn - sham equation on a given effective potential which is a critical part of all dft calculations, and monitor orbital energies and orbital shapes. we use a combination of gaussian process regression and a genetic algorithm to reduce the collocation point set size by more than an order of magnitude ( from about 51, 000 points to 2, 000 points ) while retaining mhartree accuracy. | arxiv:1904.07122 |
complex mechanical systems such as vehicle powertrains are inherently subject to multiple nonlinearities and uncertainties arising from parametric variations. modeling and calibration errors are therefore unavoidable, making the transfer of control systems from simulation to real - world systems a critical challenge. traditional robust controls have limitations in handling certain types of nonlinearities and uncertainties, requiring a more practical approach capable of comprehensively compensating for these various constraints. this study proposes a new robust control approach using the framework of deep reinforcement learning ( drl ). the key strategy lies in the synergy among domain randomization - based drl, long short - term memory ( lstm ) - based actor and critic networks, and model - based control ( mbc ). the problem setup is modeled via the latent markov decision process ( lmdp ), a set of vanilla mdps, for a controlled system subject to uncertainties and nonlinearities. in lmdp, the dynamics of an environment simulator is randomized during training to improve the robustness of the control system to real testing environments. the randomization increases training difficulties as well as conservativeness of the resultant control system ; therefore, progress is assisted by concurrent use of a model - based controller based on a nominal system model. compared to traditional drl - based controls, the proposed controller design is smarter in that we can achieve a high level of generalization ability with a more compact neural network architecture and a smaller amount of training data. the proposed approach is verified via practical application to active damping for a complex powertrain system with nonlinearities and parametric variations. comparative tests demonstrate the high robustness of the proposed approach. | arxiv:2504.19715 |
we construct classical solutions in quiver gauge theories on d0 - branes probing toric del pezzo singularities in calabi - yau manifolds. our solutions represent d4 - branes wrapped around fuzzy del pezzo surfaces. we study the fluctuation spectrum around the fuzzy cp ^ 2 solution in detail. we also comment on possible applications of our fuzzy del pezzo surfaces to the fuzzy version of f - theory, dubbed f ( uzz ) theory. | arxiv:1008.5012 |
we use phenomenological nonlocal lagrangians, which lead to non trivial forms for the quark propagator, to describe the pion. we define a procedure, based on the dyson - schwinger equations, for the calculation of the pion parton distributions at low q ^ 2. the obtained parton distributions fulfill all the wishful properties. using a convolution approach we incorporate the composite character of the constituent quarks in the formalism. we evolve, using the renormalization group, the calculated parton distributions to the experimental scale and compare favorably with the data and draw conclusions. | arxiv:hep-ph/0505102 |
we discuss a microscopic mechanism of the spin - tiplet superconductivity in the quasi - two - dimensional ruthenium oxide sr2ruo4 on the basis of two - dimensional three - band hubbard model. we solve the linearized eliashberg equation by taking into account the full momentum - frequency dependence of the order parameter for the spin - triplet and the spin - singlet states, and estimate the transition temperature as a function of the coulomb integrals. the effective pairing interaction is expanded perturbatively with respect to the coulomb interaction at the ru sites up to the third order. as a result, we show that the spin - triplet p - wave state is more stable than the spin - singlet d - wave state for moderately strong coulomb interaction. our results suggest that one of the three bands, $ \ gamma $, plays a dominant role in the superconducting transition, and the pairing on the other two bands ( $ \ alpha $ and $ \ beta $ ) is induced passively through the inter - orbit couplings. the most significant momentum dependence for the p - wave pairing originates from the vertex correction terms, while the incommensurate antiferromagnetic spin fluctuations, which are observed in inelastic neutron scattering experiments, are expected to disturb the p - wave pairing by enhancing the d - wave pairing. therefore we can regard the spin - triplet superconductivity in sr2ruo4 as one of the natural results of the electron correlations, and cannot consider as a result of some strong magnetic fluctuations. we will also mention the normal fermi liquid properties of sr2ruo4. | arxiv:cond-mat/0203453 |
n this paper we formulate necessary conditions for the integrability in the jacobi sense of newton equations $ \ ddot \ vq = - \ vf ( \ vq ) $, where $ \ vq \ in \ c ^ n $ and all components of $ \ vf $ are polynomial and homogeneous of the same degree $ l $. these conditions are derived from an analysis of the differential galois group of the variational equations along special particular solutions of the newton equations. we show that, taking all admissible particular solutions, we restrict considerably the set of newton ' s equations satisfying the necessary conditions for the integrability. moreover, we apply the obtained conditions for a detailed analysis of the newton equations with two degrees of freedom ( i. e., $ n = 2 $ ). we demonstrate the strength of the obtained results analyzing general cases with $ \ deg f _ i = l < 4 $. for $ l = 3 $ we found an integrable case when the newton equations have two polynomial first integrals and both of them are of degree four in the momenta $ p _ 1 = \ dot q _ 1 $, and $ p _ 2 = \ dot q _ 2 $. moreover, for an arbitrary $ k $, we found a family of newton equations depending on one parameter $ \ lambda $. for an arbitrary value of $ \ lambda $ one quadratic in the momenta first integral exist. we distinguish infinitely many values of $ \ lambda $ for which the system is integrable or superintegrable with additional polynomial first integrals which seemingly can be of an arbitrarily high degree with respect to the momenta. | arxiv:nlin/0701058 |
large vision - language models ( lvlms ) have demonstrated remarkable capabilities in various multimodal tasks. however, their potential in the medical domain remains largely unexplored. a significant challenge arises from the scarcity of diverse medical images spanning various modalities and anatomical regions, which is essential in real - world medical applications. to solve this problem, in this paper, we introduce omnimedvqa, a novel comprehensive medical visual question answering ( vqa ) benchmark. this benchmark is collected from 73 different medical datasets, including 12 different modalities and covering more than 20 distinct anatomical regions. importantly, all images in this benchmark are sourced from authentic medical scenarios, ensuring alignment with the requirements of the medical field and suitability for evaluating lvlms. through our extensive experiments, we have found that existing lvlms struggle to address these medical vqa problems effectively. moreover, what surprises us is that medical - specialized lvlms even exhibit inferior performance to those general - domain models, calling for a more versatile and robust lvlm in the biomedical field. the evaluation results not only reveal the current limitations of lvlm in understanding real medical images but also highlight our dataset ' s significance. our code with dataset are available at https : / / github. com / opengvlab / multi - modality - arena. | arxiv:2402.09181 |
we investigate the structural conditions for metamagnetism in mnp and related materials using density functional theory. a magnetic stability plot is constructed taking into account the two shortest mn - mn distances. we find that a particular mn - mn separation plays the dominant role in determining the change from antiferromagnetic to ferromagnetic order in such systems. we establish a good correlation between our calculations and structural and magnetic data from the literature. based on our approach it should be possible to find new mn - containing alloys that possess field - induced metamagnetism and associated magnetocaloric effects. | arxiv:1003.5193 |
we report on a recent investigation on heavy quarkonium hybrids that goes beyond the usual born - oppenheimer approximation by including not only the mixing between nearby hybrid states but also the mixing with quarkonium states. we use a systematic effective field theory framework based on nrqcd together with lattice qcd inputs. short and long distance constraints from weak coupling pnrqcd and the qcd effective string theory are also employed. we calculate the quarkonium and hybrid spectrum for charmonium and bottomonium, and estimate a number of decay widths. most of the isospin zero $ xyz $ resonances fit in our spectrum either as quarkonia or as hybrid states. the mixing of hybrid states with quarkonia produces enhanced spin symmetry violations, which are instrumental to understand certain decays. we also present new results on the hyperfine splittings. | arxiv:1709.08038 |
unsupervised domain adaptation ( uda ) aims to transfer the knowledge on a labeled source domain distribution to perform well on an unlabeled target domain. recently, the deep self - training involves an iterative process of predicting on the target domain and then taking the confident predictions as hard pseudo - labels for retraining. however, the pseudo - labels are usually unreliable, and easily leading to deviated solutions with propagated errors. in this paper, we resort to the energy - based model and constrain the training of the unlabeled target sample with the energy function minimization objective. it can be applied as a simple additional regularization. in this framework, it is possible to gain the benefits of the energy - based model, while retaining strong discriminative performance following a plug - and - play fashion. we deliver extensive experiments on the most popular and large scale uda benchmarks of image classification as well as semantic segmentation to demonstrate its generality and effectiveness. | arxiv:2101.00316 |
##ists at the asilomar conference center in pacific grove, california. the goal was to discuss the potential impact of the hypothetical possibility that robots could become self - sufficient and able to make their own decisions. they discussed the extent to which computers and robots might be able to acquire autonomy, and to what degree they could use such abilities to pose threats or hazards. some machines are programmed with various forms of semi - autonomy, including the ability to locate their own power sources and choose targets to attack with weapons. also, some computer viruses can evade elimination and, according to scientists in attendance, could therefore be said to have reached a " cockroach " stage of machine intelligence. the conference attendees noted that self - awareness as depicted in science - fiction is probably unlikely, but that other potential hazards and pitfalls exist. frank s. robinson predicts that once humans achieve a machine with the intelligence of a human, scientific and technological problems will be tackled and solved with brainpower far superior to that of humans. he notes that artificial systems are able to share data more directly than humans, and predicts that this would result in a global network of super - intelligence that would dwarf human capability. robinson also discusses how vastly different the future would potentially look after such an intelligence explosion. = = hard or soft takeoff = = in a hard takeoff scenario, an artificial superintelligence rapidly self - improves, " taking control " of the world ( perhaps in a matter of hours ), too quickly for significant human - initiated error correction or for a gradual tuning of the agent ' s goals. in a soft takeoff scenario, the ai still becomes far more powerful than humanity, but at a human - like pace ( perhaps on the order of decades ), on a timescale where ongoing human interaction and correction can effectively steer the ai ' s development. ramez naam argues against a hard takeoff. he has pointed out that we already see recursive self - improvement by superintelligences, such as corporations. intel, for example, has " the collective brainpower of tens of thousands of humans and probably millions of cpu cores to... design better cpus! " however, this has not led to a hard takeoff ; rather, it has led to a soft takeoff in the form of moore ' s law. naam further points out that the computational complexity of higher intelligence may be much greater than linear, such that " creating a mind of intelligence 2 is probably more than twice as hard as creating a mind of intelligence 1. " j. st | https://en.wikipedia.org/wiki/Technological_singularity |
in this paper we study the parabolic anderson equation \ partial u ( x, t ) / \ partial t = \ kappa \ delta u ( x, t ) + \ xi ( x, t ) u ( x, t ), x \ in \ z ^ d, t \ geq 0, where the u - field and the \ xi - field are \ r - valued, \ kappa \ in [ 0, \ infty ) is the diffusion constant, and $ \ delta $ is the discrete laplacian. the initial condition u ( x, 0 ) = u _ 0 ( x ), x \ in \ z ^ d, is taken to be non - negative and bounded. the solution of the parabolic anderson equation describes the evolution of a field of particles performing independent simple random walks with binary branching : particles jump at rate 2d \ kappa, split into two at rate \ xi \ vee 0, and die at rate ( - \ xi ) \ vee 0. our goal is to prove a number of basic properties of the solution u under assumptions on $ \ xi $ that are as weak as possible. throughout the paper we assume that $ \ xi $ is stationary and ergodic under translations in space and time, is not constant and satisfies \ e ( | \ xi ( 0, 0 ) | ) < \ infty, where \ e denotes expectation w. r. t. \ xi. under a mild assumption on the tails of the distribution of \ xi, we show that the solution to the parabolic anderson equation exists and is unique for all \ kappa \ in [ 0, \ infty ). our main object of interest is the quenched lyapunov exponent \ lambda _ 0 ( \ kappa ) = \ lim _ { t \ to \ infty } \ frac { 1 } { t } \ log u ( 0, t ). under certain weak space - time mixing conditions on \ xi, we show the following properties : ( 1 ) \ lambda _ 0 ( \ kappa ) does not depend on the initial condition u _ 0 ; ( 2 ) \ lambda _ 0 ( \ kappa ) < \ infty for all \ kappa \ in [ 0, \ infty ) ; ( 3 ) \ kappa \ mapsto \ lambda _ 0 ( \ kappa ) is continuous on [ 0, \ infty ) but not lipschitz at 0. we further conjecture : ( 4 ) \ lim _ { \ kappa \ to | arxiv:1208.0330 |
we prove that the set of busemann points ( the limits of almost - geodesic rays ) is nowhere dense in the horoboundary of the teichm \ " uller metric for all teichm \ " uller spaces of complex dimension strictly larger than 1. this shows that the teichm \ " uller metric is far from having non - positive curvature in a certain sense. | arxiv:2501.17262 |
we propose a new link between entropy and area : an eternal black hole with an er bridge with cross - section $ a $ can carry a macroscopic amount of quantum information, or be in a mixed state, with entropy bounded by $ s \ leq a / 4g _ n $. we substantiate our proposal in the context of ads3 and jt gravity, by using the island prescription and replica wormhole method for computing the black hole entropy. we argue that the typical mixed state of a two sided black hole takes the form of an entangled ` thermo - mixed double ' state with only classical correlations between the two sides. our result for the von neumann entropy of a post - page time two - sided black hole is smaller by a factor of two from previous answers. our reasoning implies that black hole quantum information is topologically protected, similar to the information stored inside a topological quantum memory. | arxiv:2003.13117 |
in the standard model, the permutation symmetry among the three generations of fundamental fermions is usually regarded to be broken by the higgs couplings. it is found that the symmetry is restored if we include the mass matrix parameters as physical variables which transform appropriately under the symmetry operation. known relations between these variables, such as the renormalization group equations, as well as formulas for neutrino oscillations ( in vacuum and in matter ), are shown to be covariant tensor equations under the permutation symmetry group. | arxiv:1805.05600 |
let $ s _ { n } f $ denote the $ n $ th partial sum of the vilenkin - fourier series of a function $ f \ in l ^ { 1 } ( g ) $. for $ 1 < p _ { - } \ leq p _ { + } < \ infty $, we characterize all exponents $ p ( \ cdot ) $ for which the convergence of $ s _ { n } f $ to $ f $ in $ l ^ { p ( \ cdot ) } ( g ) $ holds whenever $ f \ in l ^ { p ( \ cdot ) } ( g ) $. | arxiv:2210.11331 |
the interplay of migration, recombination, and dissociation of excitons in disordered media is studied theoretically in the low temperature regime. an exact expression for the photoluminescence spectrum is obtained. the theory is applied to describe the electric field - induced photoluminescence - quenching experiments by kersting et al. [ phys. rev. lett. 73, 1440 ( 1994 ) ] and deussen et al. [ synth. met. 73, 123 ( 1995 ) ] on conjugated polymer systems. good agreement with experiment is obtained using an on - chain dissociation mechanism, which implies a separation of the electron - hole pair along the polymer chain. | arxiv:cond-mat/9607054 |
structural health monitoring ( shm ) has been an active research area for the last three decades, and has accumulated a number of critical advances over that period, as can be seen in the literature. however, shm is still facing challenges because of the paucity of damage - state data, operational and environmental fluctuations, repeatability issues, and changes in boundary conditions. these issues present as inconsistencies in the captured features and can have a huge impact on the practical implementation, but more critically, on the generalisation of the technology. population - based shm has been designed to address some of these concerns by modelling and transferring missing information using data collected from groups of similar structures. in this work, vibration data were collected from four healthy, nominally - identical, full - scale composite helicopter blades. manufacturing differences ( e. g., slight differences in geometry and / or material properties ), among the blades presented as variability in their structural dynamics, which can be very problematic for shm based on machine learning from vibration data. this work aims to address this variability by defining a general model for the frequency response functions of the blades, called a form, using mixtures of gaussian processes. | arxiv:2203.07115 |
recently a high precision spectroscopic investigation of the ef ^ 1 \ sigma _ g ^ + - x ^ 1 \ sigma _ g ^ + system of molecular hydrogen was reported yielding information on qed and relativistic effects in a sequence of rotational quantum states in the x ^ 1 \ sigma ^ + _ g $ ground state of the h _ 2 molecule [ e. j. salumbides et al., phys. rev. lett. 107, 043005 ( 2011 ) ]. the present paper presents a more detailed description of the methods and results. furthermore, the paper serves as a stepping stone towards a continuation of the previous study by extending the known level structure of the ef ^ 1 \ sigma ^ + _ g state to highly excited rovibrational levels through doppler - free two photon spectroscopy. based on combination differences between vibrational levels in the ground state, and between three rotational branches ( o, q and s branches ) assignments of excited ef ^ 1 \ sigma ^ + _ g levels, involving high vibrational and rotational quantum numbers, can be unambiguously made. for the higher ef ^ 1 \ sigma ^ + _ g levels, where no combination differences are available, calculations were performed using the multi - channel quantum defect method, for a broad class of vibrational and rotational levels up to j = 19. these predictions were used for assigning high - j ef - levels and are found to be accurate within 5 cm ^ - 1. | arxiv:1301.0403 |
visual simultaneous localisation and mapping ( vslam ) is a key enabling technology for small embedded robotic systems such as aerial vehicles. recent advances in equivariant filter and observer design offer the potential of a new generation of highly robust algorithms with low memory and computation requirements for embedded system applications. this paper studies observer design on the symmetry group proposed in previous work by the authors, in the case where inverse depth measurements are available. exploiting this symmetry leads to a simple fully non - linear gradient based observer with almost global asymptotic and local exponential stability properties. simulation experiments verify the observer design, and demonstrate that the proposed observer achieves similar accuracy to the widely used extended kalman filter with significant gains in processing time ( linear verses quadratic bounds with respect to number of landmarks ) and qualitative improvements in robustness. | arxiv:2005.14347 |
language modality within the vision language pretraining framework is innately discretized, endowing each word in the language vocabulary a semantic meaning. in contrast, visual modality is inherently continuous and high - dimensional, which potentially prohibits the alignment as well as fusion between vision and language modalities. we therefore propose to " discretize " the visual representation by joint learning a codebook that imbues each visual token a semantic. we then utilize these discretized visual semantics as self - supervised ground - truths for building our masked image modeling objective, a counterpart of masked language modeling which proves successful for language models. to optimize the codebook, we extend the formulation of vq - vae which gives a theoretic guarantee. experiments validate the effectiveness of our approach across common vision - language benchmarks. | arxiv:2208.00475 |
the polya group of a number field k is the subgroup of the class group of k generated by the classes of the products of the maximal ideals with same norm. a polya field is a number field whose polya group is trivial. our purpose is to start with known assertions about polya fields to find results concerning polya groups. in this second paper we describe the polya group of some non - galoisian extensions of q. | arxiv:1811.03648 |
we study non - relativistic supersymmetric field theories in diverse dimensions. the theories consist of scalars and fermions and possess two, four or eight real supercharges. we analyze their spontaneous supersymmetry breaking structure and calculate the gapless spectrum. we calculate the perturbative quantum corrections at the supersymmetric vacua and show that while supersymmetry is preserved, scale invariance is broken and the theories are ir free. | arxiv:1703.04740 |
leonid levin ( arxiv. org / abs / cs / 0503039v14, p. 7 ) published a new ( and very nice ) proof of g \ ' acs - ku \ v { c } era ' s theorem that occupies only a few lines when presented in his style. we try to explain more details and discuss the connection of this proof with image randomness theorems, making explicit some result ( see proposition 4 ) that is implicit in levin ' s exposition. then we review the previous work about the oracle use when reducing a given sequence to another one, and its connection with algorithmic dimension theory. | arxiv:2111.00516 |
mobility - on - demand ( mod ) systems, especially ride - hailing systems, have seen tremendous growth in recent years. these systems provide user - centric mobility services, whose users expect a high level of convenience. waiting for a response after an app request and eventually learning after a long period of time that no vehicle is available is hardly acceptable. this study investigates the use - case where users should be served within a certain maximum waiting time. under certain assumptions, which are reasonable for an attractive mod business model, it can be shown that an operator using dynamic state optimization can communicate a rejection to users after the first iteration, thereby eliminating unnecessary waiting time before these users would leave the system. furthermore, early operator rejections reduce the dimension of subsequent customer - vehicle assignment problems, thereby saving computational resources and solving the problems faster. in turn, this allows shorter re - optimization cycles and once again faster responses, i. e. a better user experience. | arxiv:2104.01326 |
in this paper, we introduce a generalized birth process ( gbp ) which performs jumps of size $ 1, 2, \ dots, k $ whose rates depend on the state of the process at time $ t \ geq0 $. we derive a non - exploding condition for it. the system of differential equations that governs its state probabilities is obtained. in this governing system of differential equations, we replace the first order derivative with caputo fractional derivative to obtain a fractional variant of the gbp, namely, the generalized fractional birth process ( gfbp ). the laplace transform of the state probabilities of this fractional variant is obtained whose inversion yields its one - dimensional distribution. it is shown that the gfbp is equal in distribution to a time - changed version of the gbp, and this result is used to obtain a non - exploding condition for it. a limiting case of the gfbp is considered in which jump of any size $ j \ ge1 $ is possible. also, we discuss a state dependent version of it. | arxiv:2110.01190 |
we describe v02 of igmspec, a database of publically available ultraviolet, optical, and near - infrared spectra that probe the intergalactic medium ( igm ). this database, a child of the specdb repository in the specdb github organization, comprises 403277 unique sources and 434686 spectra obtained with the world ' s greatest observatories. all of these data are distributed in a single ~ 25 gb hdf5 file maintained at the university of california observatories and the university of california, santa cruz. the specdb software package includes python scripts and modules for searching the source catalog and spectral datasets, and software links to the linetools package for spectral analysis. the repository also includes software to generate private spectral datasets that are compliant with international virtual observatory alliance ( ivoa ) protocols and a python - based interface for ivoa simple spectral access queries. future versions of igmspec will ingest other sources ( e. g. gamma - ray burst afterglows ) and other surveys as they become publicly available. the overall goal is to include every spectrum that effectively probes the igm. future databases of specdb may include publicly available galaxy spectra ( exgalspec ) and published supernovae spectra ( snspec ). the community is encouraged to join the effort on github : https : / / github. com / specdb | arxiv:1703.04695 |
we study properties of waves of frequencies above the photospheric acoustic cut - off of $ \ approx $ 5. 3 mhz, around four active regions, through spatial maps of their power estimated using data from helioseismic and magnetic imager ( hmi ) and atmospheric imaging assembly ( aia ) onboard solar dynamics observatory ( sdo ). the wavelength channels 1600 { \ aa } and 1700 { \ aa } from aia are now known to capture clear oscillation signals due to helioseismic p modes as well as waves propagating up through to the chromosphere. here we study in detail, in comparison with hmi doppler data, properties of the power maps, especially the so called ' acoustic halos ' seen around active regions, as a function of wave frequencies, inclination and strength of magnetic field ( derived from the vector field observations by hmi ) and observation height. we infer possible signatures of ( magneto - ) acoustic wave refraction from the observation height dependent changes, and hence due to changing magnetic strength and geometry, in the dependences of power maps on the photospheric magnetic quantities. we discuss the implications for theories of p mode absorption and mode conversions by the magnetic field. | arxiv:1206.5874 |
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