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we introduce a class of half lightlike submanifolds of almost contact b - metric manifolds and prove that such submanifolds are semi - riemannian with respect to the associated b - metric. object of investigations are also minimal of the considered submanifolds and a non - trivial example for them is given.
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arxiv:2003.06605
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this paper presents an application of partial contraction analysis to the study of global synchronization in discrete chaotic systems. explicit sufficient conditions on the coupling strength of networks of discrete oscillators are derived. numerical examples and applications to simple systems are presented. previous researches have shown numerically that the systems under study, when arranged in a network, exhibits rich and complex patterns that can dynamically change in response to variations in the environment. we show how this ` ` adaptation ' ' process strongly depends on the coupling characteristics of the network. other potential applications of synchronized chaotic oscillators are discussed.
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arxiv:nlin/0609064
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we establish an $ h $ - principle for exact lagrangian immersions with transverse self - intersections and the minimal, or near - minimal number of double points. one corollary of our result is that any orientable closed 3 - manifold admits an exact lagrangian immersion into standard symplectic 6 - space $ \ r ^ 6 _ \ st $ with exactly one transverse double point. our construction also yields a lagrangian embedding $ s ^ 1 \ times s ^ 2 \ to \ r ^ 6 _ \ st $ with vanishing maslov class.
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arxiv:1303.0588
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to train a deep neural network to mimic the outcomes of processing sequences, a version of conditional generalized adversarial network ( cgan ) can be used. it has been observed by others that cgan can help to improve the results even for deterministic sequences, where only one output is associated with the processing of a given input. surprisingly, our cgan - based tests on deterministic geophysical processing sequences did not produce a real improvement compared to the use of an $ l _ p $ loss ; we here propose a first theoretical explanation why. our analysis goes from the non - deterministic case to the deterministic one. it led us to develop an adversarial way to train a content loss that gave better results on our data.
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arxiv:2011.00835
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we relate the mather invariant of diffeomorphisms of the ( closed ) interval to their asymptotic distortion. for maps with only parabolic fixed points, we show that the former is trivial if and only if the latter vanishes. as a consequence, we obtain that such a diffeomorphism of the interval with no fixed point in the interior contains the identity in the closure of its c ^ { 1 + bv } conjugacy class if and only if it is the time - 1 map of a c ^ 1 vector field. a corollary of this is that diffeomorphisms that do not arise from vector fields are undistorted in the whole group of interval interval diffeomorphisms. several related results in other regularity classes are obtained, and many open questions are addressed.
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arxiv:1912.09305
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we consider a continuous path of bounded symmetric fredholm bilinear forms with arbitrary endpoints on a real hilbert space, and we prove a formula that gives the spectral flow of the path in terms of the spectral flow of the restriction to a finite codimensional closed subspace. we also discuss the case of restrictions to a continuous path of finite codimensional closed subspaces. as an application of the formula, we introduce the notion of spectral flow for a periodic semi - riemannian geodesic, and we compute its value in terms of the maslov index.
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arxiv:0801.4102
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this work devotes to investigate the dynamical emergence of black hole shadow from gravitational lensing in dynamical spacetime by using the collapsing boson star. two characterized scenarios are adopted with or without considering the time delay of light propagation. as the boson star evolves, new einstein rings emerge from the lensing center, with their radius gradually increasing, and their number continues to grow infinitely before the light - ring forms. the shadow forms instantaneously at the moment the black hole appears when ignoring the time delay of light propagation. considering the time delay for light propagation in dynamical spacetime, a more intricate process of the shadow formation is uncovered : it first appears as a minute dot in the lensing center, then gradually grows as the black hole grows, eventually expands the inner region of the light - ring. during the quasi - stable phases of boson star and black hole, the lensing and shadow structures from two scenarios are nearly identical and remain almost unchanged. our results present the universal dynamic patterns of the lensing and shadow structures, and reveal the potential observed phenomena near the collapsing star and the event horizon of the newly formed black hole.
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arxiv:2503.14159
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we study the liquid - gas phase transition of stellar matter with the inclusion of the finite - size effect from surface and coulomb energies. the equilibrium conditions for two coexisting phases are determined by minimizing the total free energy including the surface and coulomb contributions, which are different from the gibbs conditions used in the bulk calculations. the finite - size effect can significantly reduce the region of the liquid - gas mixed phase. the influence of the symmetry energy on the liquid - gas phase transition is investigated with the inclusion of finite - size effects. it is found that the slope of the symmetry energy plays an important role in determining the boundary and properties of the mixed phase.
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arxiv:1602.06409
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diffusive transport of particles or, more generally, small objects is a ubiquitous feature of physical and chemical reaction systems. in configurations containing confining walls or constrictions transport is controlled both by the fluctuation statistics of the jittering objects and the phase space available to their dynamics. consequently, the study of transport at the macro - and nanoscales must address both brownian motion and entropic effects. with this survey we report on recent advances in the theoretical and numerical investigation of stochastic transport occurring either in micro - sized geometries of varying cross section or in narrow channels wherein the diffusing particles are hindered from passing each other ( single file diffusion ). for particles undergoing biased diffusion in static suspension media enclosed by confining geometries, transport exhibits intriguing features such as ( i ) a decrease of nonlinear mobility with increasing temperature or, also, ( ii ) a broad excess peak of the effective diffusion above the free diffusion limit. these paradoxical aspects can be understood in terms of entropic contributions resulting from the restricted dynamics in phase space. if, in addition, the suspension medium is subjected to external, time - dependent forcing, rectification or segregation of the diffusing brownian particles becomes possible. likewise, the diffusion in very narrow, spatially modulated channels gets modified via contact particle - particle interactions, which induce anomalous sub - diffusion. the effective sub - diffusion constant for a driven single file also develops a resonance - like structure as a function of the confining coupling constant.
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arxiv:0808.2345
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optical fiber links have demonstrated their ability to transfer the ultra - stable clock signals. in this paper we propose and demonstrate a new scheme to transfer both time and radio frequency with the same wavelength based on coherent demodulation technique. time signal is encoded as a binary phase - shift keying ( bpsk ) to the optical carrier using electro optic modulator ( eom ) by phase modulation and makes sure the frequency signal free from interference with single pulse. the phase changes caused by the fluctuations of the transfer links are actively cancelled at local site by optical delay lines. radio frequency with 1ghz and time signal with one pulse per second ( 1pps ) transmitted over a 110km fiber spools are obtained. the experimental results demonstrate that frequency instabilities of 1. 7e - 14 at 1s and 5. 9e - 17 at 104s. moreover, time interval transfer of 1pps signal reaches sub - ps stability after 1000s. this scheme offers advantages with respect to reduce the channel in fiber network, and can keep time and frequency signal independent of each other.
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arxiv:1909.03197
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we analyze a modification of the richards growth model by introducing a time - dependent perturbation in the growth rate. this modification becomes effective at a special switching time, which represents the first - crossing - time of the richards growth curve through a given constant boundary. the relevant features of the modified growth model are studied and compared with those of the original one. a sensitivity analysis on the switching time is also performed. then, we define two different stochastic processes, i. e. a non - homogeneous linear birth - death process and a lognormal diffusion process, such that their means identify to the growth curve under investigation. for the diffusion process, we address the problem of parameters estimation through the maximum likelihood method. the estimates are obtained via meta - heuristic algorithms ( namely, simulated annealing and ant lion optimizer ). a simulation study to validate the estimation procedure is also presented, together with a real application to oil production in france. special attention is devoted to the approximation of switching time density, viewed as the first - passage - time density for the lognormal process.
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arxiv:2410.22860
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in csl ' 99 roversi pointed out that the turing machine encoding of girard ' s seminal paper " light linear logic " has a flaw. moreover he presented a working version of the encoding in light affine logic, but not in light linear logic. in this paper we present a working version of the encoding in light linear logic. the idea of the encoding is based on a remark of girard ' s tutorial paper on linear logic. the encoding is also an example which shows usefulness of additive connectives. moreover we also consider a nondeterministic extension of light linear logic. we show that the extended system is np - complete in the same meaning as p - completeness of light linear logic.
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arxiv:cs/0410034
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we present a new paradigm for understanding optical absorption and hot electron dynamics experiments in graphene. our analysis pivots on assigning proper importance to phonon assisted indirect processes and bleaching of direct processes. we show indirect processes figure in the excess absorption in the uv region. experiments which were thought to indicate ultrafast relaxation of electrons and holes, reaching a thermal distribution from an extremely non - thermal one in under 5 - 10 fs, instead are explained by the nascent electron and hole distributions produced by indirect transitions. these need no relaxation or ad - hoc energy removal to agree with the observed emission spectra and fast pulsed absorption spectra. the fast emission following pulsed absorption is dominated by phonon assisted processes, which vastly outnumber direct ones and are always available, connecting any electron with any hole any time. calculations are given, including explicitly calculating the magnitude of indirect processes, supporting these views.
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arxiv:1704.07500
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quadrupedal robots have emerged as versatile agents capable of locomoting and manipulating in complex environments. traditional designs typically rely on the robot ' s inherent body parts or incorporate top - mounted arms for manipulation tasks. however, these configurations may limit the robot ' s operational dexterity, efficiency and adaptability, particularly in cluttered or constrained spaces. in this work, we present locoman, a dexterous quadrupedal robot with a novel morphology to perform versatile manipulation in diverse constrained environments. by equipping a unitree go1 robot with two low - cost and lightweight modular 3 - dof loco - manipulators on its front calves, locoman leverages the combined mobility and functionality of the legs and grippers for complex manipulation tasks that require precise 6d positioning of the end effector in a wide workspace. to harness the loco - manipulation capabilities of locoman, we introduce a unified control framework that extends the whole - body controller ( wbc ) to integrate the dynamics of loco - manipulators. through experiments, we validate that the proposed whole - body controller can accurately and stably follow desired 6d trajectories of the end effector and torso, which, when combined with the large workspace from our design, facilitates a diverse set of challenging dexterous loco - manipulation tasks in confined spaces, such as opening doors, plugging into sockets, picking objects in narrow and low - lying spaces, and bimanual manipulation.
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arxiv:2403.18197
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we present spectroscopy and orbital periods porb of four relatively little - studied cataclysmic variable stars. the stars and their periods are : af cam, porb = 0. 324 ( 1 ) d ( the daily cycle count is slightly ambiguous ) ; v2069 cyg ( = rx j2123. 7 + 4217 ), 0. 311683 ( 2 ) d ; pg 0935 + 075, 0. 1868 ( 3 ) d ; and kuv 03580 + 0614, 0. 1495 ( 6 ) d. v2069 cyg and kuv 03580 + 0614 both show heii lambda 4686 emission comparable in strength to h beta. v2069 cyg appears to be a luminous novalike variable, and the strong heii suggests it may be an intermediate polar. the period of kuv 03580 + 0614 is similar to members of the sw sex - type novalike variables, and it shows the phase - dependent absorption in the balmer and he i lines typical of this subclass. af cam shows absorption features from a k - type secondary, as expected given its rather long orbital period. the secondary spectrum and the outburst magnitude both suggest that af cam is about 1 kpc distant. the spectrum of pg 0935 + 075 resembles that of a dwarf nova at minimum light, with a noticeable contribution from an m - dwarf secondary star. the secondary spectrum and a tentative outburst magnitude both suggest a distance near 500 pc.
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arxiv:astro-ph/0105499
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motivated by recent data analyses in biomedical imaging studies, we consider a class of image - on - scalar regression models for imaging responses and scalar predictors. we propose using flexible multivariate splines over triangulations to handle the irregular domain of the objects of interest on the images, as well as other characteristics of images. the proposed estimators of the coefficient functions are proved to be root - n consistent and asymptotically normal under some regularity conditions. we also provide a consistent and computationally efficient estimator of the covariance function. asymptotic pointwise confidence intervals and data - driven simultaneous confidence corridors for the coefficient functions are constructed. our method can simultaneously estimate and make inferences on the coefficient functions while incorporating spatial heterogeneity and spatial correlation. a highly efficient and scalable estimation algorithm is developed. monte carlo simulation studies are conducted to examine the finite - sample performance of the proposed method, which is then applied to the spatially normalized positron emission tomography data of the alzheimer ' s disease neuroimaging initiative.
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arxiv:2106.01431
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the magnetic state of the single - component molecular compound, [ cu ( tmdt ) $ _ { 2 } $ ], is investigated by means of $ ^ { 1 } $ h - nmr. an abrupt spectral broadening below 13 k and a sharp peak in nuclear spin - lattice relaxation rate, $ t _ { 1 } ^ { - 1 } $, at 13 k are observed as clear manifestations of a second - order antiferromagnetic transition, which is consistent with the previously reported magnetic susceptibility and epr measurement. the ordered moment is estimated at $ 0. 22 - 0. 45 $ $ { \ mu } _ { \ rm b } $ / molecule. the temperature - dependence of $ t _ { 1 } ^ { - 1 } $ above the transition temperature indicates one - dimensional spin dynamics and supports that the spins are on the central part of the molecule differently from other isostructural compounds.
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arxiv:1202.2691
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this work proposes a machine - learning framework for constructing statistical models of errors incurred by approximate solutions to parameterized systems of nonlinear equations. these approximate solutions may arise from early termination of an iterative method, a lower - fidelity model, or a projection - based reduced - order model, for example. the proposed statistical model comprises the sum of a deterministic regression - function model and a stochastic noise model. the method constructs the regression - function model by applying regression techniques from machine learning ( e. g., support vector regression, artificial neural networks ) to map features ( i. e., error indicators such as sampled elements of the residual ) to a prediction of the approximate - solution error. the method constructs the noise model as a mean - zero gaussian random variable whose variance is computed as the sample variance of the approximate - solution error on a test set ; this variance can be interpreted as the epistemic uncertainty introduced by the approximate solution. this work considers a wide range of feature - engineering methods, data - set - construction techniques, and regression techniques that aim to ensure that ( 1 ) the features are cheaply computable, ( 2 ) the noise model exhibits low variance ( i. e., low epistemic uncertainty introduced ), and ( 3 ) the regression model generalizes to independent test data. numerical experiments performed on several computational - mechanics problems and types of approximate solutions demonstrate the ability of the method to generate statistical models of the error that satisfy these criteria and significantly outperform more commonly adopted approaches for error modeling.
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arxiv:1808.02097
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this paper explores minimum bayes risk ( mbr ) decoding for self - improvement in machine translation ( mt ), particularly for domain adaptation and low - resource languages. we implement the self - improvement process by fine - tuning the model on its mbr - decoded forward translations. by employing comet as the mbr utility metric, we aim to achieve the reranking of translations that better aligns with human preferences. the paper explores the iterative application of this approach and the potential need for language - specific mbr utility metrics. the results demonstrate significant enhancements in translation quality for all examined language pairs, including successful application to domain - adapted models and generalisation to low - resource settings. this highlights the potential of comet - guided mbr for efficient mt self - improvement in various scenarios.
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arxiv:2405.11937
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we evaluate the fermion propagator in parity - conserving qed _ 3 with n flavours, in the context of an ir domain approximation. this provides results which are non - perturbative in the loopwise expansion sense. we include fermion - loop effects, and show that they are relevant to the chiral symmetry breaking phenomenon, that can be understood in this context.
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arxiv:hep-th/0303226
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the classic lorenz equations were originally derived from the two - dimensional rayleigh - b \ ' enard convection system considering an idealised case with the lowest order of harmonics. although the low - order lorenz equations have traditionally served as a minimal model for chaotic and intermittent atmospheric motions, even the dynamics of the two - dimensional rayleigh - b \ ' enard convection system is not fully represented by the lorenz equations, and such differences have yet to be clearly identified in a systematic manner. in this paper, the convection problem is revisited through an investigation of various dynamical behaviors exhibited by a two - dimensional direct numerical simulation ( dns ) and the generalized expansion of the lorenz equations ( gele ) derived by considering additional higher - order harmonics in the spectral expansions of periodic solutions. notably, the gele allows us to understand how nonlinear interactions among high - order modes alter the dynamical features of the lorenz equations including fixed points, chaotic attractors, and periodic solutions. it is verified that numerical solutions of the dns can be recovered from the solutions of gele when we consider the system with sufficiently high - order harmonics. at the lowest order, the classic lorenz equations are recovered from gele. unlike in the lorenz equations, we observe limit tori, which are the multi - dimensional analogue of limit cycles, in the solutions of the dns and gele at high orders. initial condition dependency in the dns and lorenz equations is also discussed.
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arxiv:2109.04187
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in this paper, we perform the polar analysis of the spinorial fields, starting from the regular cases and up to the singular cases : we will give for the first time the polar form of the spinorial field equations for the singular cases constituted by the flag - dipole spinor fields. comments on the role of further spinor sub - classes containing majorana and weyl spinors will be sketched.
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arxiv:2004.14155
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##ismometer in 132 ce which provided instant alert to authorities in the capital luoyang that an earthquake had occurred in a location indicated by a specific cardinal or ordinal direction. although no tremors could be felt in the capital when zhang told the court that an earthquake had just occurred in the northwest, a message came soon afterwards that an earthquake had indeed struck 400 to 500 km ( 250 to 310 mi ) northwest of luoyang ( in what is now modern gansu ). zhang called his device the ' instrument for measuring the seasonal winds and the movements of the earth ' ( houfeng didong yi 地 ), so - named because he and others thought that earthquakes were most likely caused by the enormous compression of trapped air. there are many notable contributors to early chinese disciplines, inventions, and practices throughout the ages. one of the best examples would be the medieval song chinese shen kuo ( 1031 – 1095 ), a polymath and statesman who was the first to describe the magnetic - needle compass used for navigation, discovered the concept of true north, improved the design of the astronomical gnomon, armillary sphere, sight tube, and clepsydra, and described the use of drydocks to repair boats. after observing the natural process of the inundation of silt and the find of marine fossils in the taihang mountains ( hundreds of miles from the pacific ocean ), shen kuo devised a theory of land formation, or geomorphology. he also adopted a theory of gradual climate change in regions over time, after observing petrified bamboo found underground at yan ' an, shaanxi. if not for shen kuo ' s writing, the architectural works of yu hao would be little known, along with the inventor of movable type printing, bi sheng ( 990 – 1051 ). shen ' s contemporary su song ( 1020 – 1101 ) was also a brilliant polymath, an astronomer who created a celestial atlas of star maps, wrote a treatise related to botany, zoology, mineralogy, and metallurgy, and had erected a large astronomical clocktower in kaifeng city in 1088. to operate the crowning armillary sphere, his clocktower featured an escapement mechanism and the world ' s oldest known use of an endless power - transmitting chain drive. the jesuit china missions of the 16th and 17th centuries " learned to appreciate the scientific achievements of this ancient culture and made them known in europe. through their correspondence european scientists
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https://en.wikipedia.org/wiki/History_of_science
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the $ w $ boson mass $ m _ w $ in the gut inspired $ so ( 5 ) \ times u ( 1 ) \ times su ( 3 ) $ gauge - higgs unification in the randall - sundrum ( rs ) warped space is evaluated. the muon decay $ \ mu ^ - \ rightarrow e ^ - \ bar { \ nu } _ e \ nu _ \ mu $ proceeds by the exchange of not only the zero mode of the $ w $ boson $ ( w ^ { ( 0 ) } $ ) but also kaluza - klein ( kk ) excited modes $ w ^ { ( n ) } $ and $ w _ r ^ { ( n ) } $ ( $ n \ ge 1 $ ) at the tree level. the anti - de sitter curvature of the rs space also affects the relationship among the gauge couplings and the ratio of $ m _ w $ to the $ z $ boson mass $ m _ z $. the $ w $ couplings of leptons and quarks also change. with the given kk mass scale $ m _ { \ rm kk } $ the range of the aharonov - bohm phase $ \ theta _ h $ in the fifth dimension is constrained. for $ m _ { \ rm kk } = 13 \, $ tev, $ 0. 085 \ lesssim \ theta _ h \ lesssim 0. 11 $ and $ 80. 381 \, { \ rm gev } \ lesssim m _ w \ lesssim 80. 407 \, { \ rm gev } $. the predicted value of $ m _ w $ for $ 13 \, { \ rm tev } \ le m _ { \ rm kk } \ le 20 \, { \ rm tev } $ lies between $ m _ w ^ { \ rm sm } = 80. 354 \ pm 0. 007 \, $ gev in the standard model and $ m _ w ^ { \ rm cdf } = 80. 4335 \ pm 0. 0094 \, $ gev, the value reported by the cdf collaboration in 2022.
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arxiv:2310.03276
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structural and physical properties determined by measurements on large single crystals of the anisotropic ferromagnet mnbi are reported. the findings support the importance of magneto - elastic effects in this material. x - ray diffraction reveals a structural phase transition at the spin reorientation temperature $ t _ { sr } $ = 90 k. the distortion is driven by magneto - elastic coupling, and upon cooling transforms the structure from hexagonal to orthorhombic. heat capacity measurements show a thermal anomaly at the crystallographic transition, which is suppressed rapidly by applied magnetic fields. effects on the transport and anisotropic magnetic properties of the single crystals are also presented. increasing anisotropy of the atomic displacement parameters for bi with increasing temperature above $ t _ { sr } $ is revealed by neutron diffraction measurements. it is likely that this is directly related to the anisotropic thermal expansion in mnbi, which plays a key role in the spin reorientation and magnetocrystalline anisotropy. the identification of the true ground state crystal structure reported here may be important for future experimental and theoretical studies of this permanent magnet material, which have to date been performed and interpreted using only the high temperature structure.
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arxiv:1411.2448
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signature verification is a critical task in many applications, including forensic science, legal judgments, and financial markets. however, current signature verification systems are often difficult to explain, which can limit their acceptance in these applications. in this paper, we propose a novel explainable offline automatic signature verifier ( asv ) to support forensic handwriting examiners. our asv is based on a universal background model ( ubm ) constructed from offline signature images. it allows us to assign a questioned signature to the ubm and to a reference set of known signatures using simple distance measures. this makes it possible to explain the verifier ' s decision in a way that is understandable to non experts. we evaluated our asv on publicly available databases and found that it achieves competitive performance with state of the art asvs, even when challenging 1 versus 1 comparison are considered. our results demonstrate that it is possible to develop an explainable asv that is also competitive in terms of performance. we believe that our asv has the potential to improve the acceptance of signature verification in critical applications such as forensic science and legal judgments.
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arxiv:2405.12695
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while neural end - to - end text - to - speech ( tts ) is superior to conventional statistical methods in many ways, the exposure bias problem in the autoregressive models remains an issue to be resolved. the exposure bias problem arises from the mismatch between the training and inference process, that results in unpredictable performance for out - of - domain test data at run - time. to overcome this, we propose a teacher - student training scheme for tacotron - based tts by introducing a distillation loss function in addition to the feature loss function. we first train a tacotron2 - based tts model by always providing natural speech frames to the decoder, that serves as a teacher model. we then train another tacotron2 - based model as a student model, of which the decoder takes the predicted speech frames as input, similar to how the decoder works during run - time inference. with the distillation loss, the student model learns the output probabilities from the teacher model, that is called knowledge distillation. experiments show that our proposed training scheme consistently improves the voice quality for out - of - domain test data both in chinese and english systems.
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arxiv:1911.02839
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recently, there has been an increasing concern about the privacy issue raised by using personally identifiable information in machine learning. however, previous portrait matting methods were all based on identifiable portrait images. to fill the gap, we present p3m - 10k in this paper, which is the first large - scale anonymized benchmark for privacy - preserving portrait matting. p3m - 10k consists of 10, 000 high - resolution face - blurred portrait images along with high - quality alpha mattes. we systematically evaluate both trimap - free and trimap - based matting methods on p3m - 10k and find that existing matting methods show different generalization capabilities when following the privacy - preserving training ( ppt ) setting, i. e., training on face - blurred images and testing on arbitrary images. to devise a better trimap - free portrait matting model, we propose p3m - net, which leverages the power of a unified framework for both semantic perception and detail matting, and specifically emphasizes the interaction between them and the encoder to facilitate the matting process. extensive experiments on p3m - 10k demonstrate that p3m - net outperforms the state - of - the - art methods in terms of both objective metrics and subjective visual quality. besides, it shows good generalization capacity under the ppt setting, confirming the value of p3m - 10k for facilitating future research and enabling potential real - world applications. the source code and dataset are available at https : / / github. com / jizhizili / p3m
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arxiv:2104.14222
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observables in quantum mechanics are represented by self - adjoint operators on hilbert space. such ubiquitous, well - known, and very foundational fact, however, is traditionally subtle to be explained in typical first classes in quantum mechanics, as well as to senior physicists who have grown up with the lesson that self - adjointness is " just technical ". the usual difficulties are to clarify the connection between the demand for certain physical features in the theory and the corresponding mathematical requirement of self - adjointness, and to distinguish between self - adjoint and hermitian operator not just at the level of the mathematical definition but most importantly from the perspective that mere hermiticity, without self - adjointness, does not ensure the desired physical requirements and leaves the theory inconsistent. in this work we organise an amount of standard facts on the physical role of self - adjointness into a coherent pedagogical path aimed at making quantum observables emerge as necessarily self - adjoint, and not merely hermitian operators. next to the central core of our line of reasoning - - the necessity of a non - trivial declaration of a domain to associate with the formal action of an observable, and the emergence of self - adjointness as a consequence of fundamental physical requirements - - we include some complementary materials consisting of a few instructive mathematical proofs and a short retrospective, ranging from the past decades to the current research agenda, on the self - adjointness problem for quantum hamiltonians of relevance in applications.
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arxiv:2012.14490
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the generalized quark - antiquark potential of n = 4 supersymmetric yang - mills theory on s ^ 3 x r calculates the potential between a pair of heavy charged particles separated by an arbitrary angle on s ^ 3 and also an angle in flavor space. it can be calculated by a wilson loop following a prescribed path and couplings, or after a conformal transformation, by a cusped wilson loop in flat space, hence also generalizing the usual concept of the cusp anomalous dimension. in ads _ 5 x s ^ 5 this is calculated by an infinite open string. i present here an open spin - chain model which calculates the spectrum of excitations of such open strings. in the dual gauge theory these are cusped wilson loops with extra operator insertions at the cusp. the boundaries of the spin - chain introduce a non - trivial reflection phase and break the bulk symmetry down to a single copy of psu ( 2 | 2 ). the dependence on the two angles is captured by the two embeddings of this algebra into \ psu ( 2 | 2 ) ^ 2, i. e., by a global rotation. the exact answer to this problem is conjectured to be given by solutions to a set of twisted boundary thermodynamic bethe ansatz integral equations. in particular the generalized quark - antiquark potential or cusp anomalous dimension is recovered by calculating the ground state energy of the minimal length spin - chain, with no sites. it gets contributions only from virtual particles reflecting off the boundaries. i reproduce from this calculation some known weak coupling perturtbative results.
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arxiv:1203.1617
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the most general electrically and magnetically charged rotating black hole solutions of 5 dimensional \ kk \ theory are given in an explicit form. various classical quantities associated with the black holes are derived. in particular, one finds the very surprising result that the gyromagnetic and gyroelectric ratios can become { \ tenit arbitrarily large }. the thermodynamic quantities of the black holes are calculated and a smarr - type formula is obtained leading to a generalized first law of black hole thermodynamics. the properties of the extreme solutions are investigated and it is shown how they naturally separate into two classes. the extreme solutions in one class are found to have two unusual properties : ( i ). their event horizons have zero angular velocity and yet they have non - zero adm angular momentum. ( ii ). in certain circumstances it is possible to add angular momentum to these extreme solutions without changing the mass or charges and yet still maintain an extreme solution. regarding the extreme black holes as elementary particles, their stability is discussed and it is found that they are stable provided they have sufficient angular momentum.
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arxiv:hep-th/9505038
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we investigate the radial number density profile and the abundance distribution of faint satellites around central galaxies in the low redshift universe using the cfht legacy survey. we consider three samples of central galaxies with magnitudes of m _ r = - 21, - 22, and - 23 selected from the sloan digital sky survey ( sdss ) group catalog of yang et al.. the satellite distribution around these central galaxies is obtained by cross - correlating these galaxies with the photometric catalogue of the cfht legacy survey. the projected radial number density of the satellites obeys a power law form with the best - fit logarithmic slope of - 1. 05, independent of both the central galaxy luminosity and the satellite luminosity. the projected cross correlation function between central and satellite galaxies exhibits a non - monotonic trend with satellite luminosity. it is most pronounced for central galaxies with m _ r = - 21, where the decreasing trend of clustering amplitude with satellite luminosity is reversed when satellites are fainter than central galaxies by more than 2 magnitudes. a comparison with the satellite luminosity functions in the milky way and m31 shows that the milky way / m31 system has about twice as many satellites as around a typical central galaxy of similar luminosity. the implications for theoretical models are briefly discussed.
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arxiv:1209.5930
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accretion physics studies the process of gravitational capture of ambient matter by massive stars. the background processes are very challenging to observe and measure due to the extreme conditions in these systems. numerical simulations play a crucial role in accretion physics because they provide the only practical method to model the complex processes occurring in accretion disks. in this review, we outline different branches of numerical simulations, such as hydrodynamic simulations, magnetohydrodynamic simulations, and monte - carlo simulations, and their methodology, and we discuss possible implications for modeling accretion physics around black holes, neutron stars, and protoplanetary disks.
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arxiv:2409.14224
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we introduce a simple class of distribution networks which withstand damage by being repairable instead of redundant. we prove a lower bound for the expected cost of repair, and show that for networks on the square and triangular lattice, this bound is achievable and results in a network with exactly three levels of structural hierarchy. we extend our results to networks subject to repeated attacks, in which the repairs themselves must be repairable. we find that, in exchange for a modest increase in repair cost, such networks are able to withstand any number of attacks.
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arxiv:1405.2185
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. all observation involves both perception and cognition. that is, one does not make an observation passively, but rather is actively engaged in distinguishing the phenomenon being observed from surrounding sensory data. therefore, observations are affected by one ' s underlying understanding of the way in which the world functions, and that understanding may influence what is perceived, noticed, or deemed worthy of consideration. in this sense, it can be argued that all observation is theory - laden. = = = the purpose of science = = = should science aim to determine ultimate truth, or are there questions that science cannot answer? scientific realists claim that science aims at truth and that one ought to regard scientific theories as true, approximately true, or likely true. conversely, scientific anti - realists argue that science does not aim ( or at least does not succeed ) at truth, especially truth about unobservables like electrons or other universes. instrumentalists argue that scientific theories should only be evaluated on whether they are useful. in their view, whether theories are true or not is beside the point, because the purpose of science is to make predictions and enable effective technology. realists often point to the success of recent scientific theories as evidence for the truth ( or near truth ) of current theories. antirealists point to either the many false theories in the history of science, epistemic morals, the success of false modeling assumptions, or widely termed postmodern criticisms of objectivity as evidence against scientific realism. antirealists attempt to explain the success of scientific theories without reference to truth. some antirealists claim that scientific theories aim at being accurate only about observable objects and argue that their success is primarily judged by that criterion. = = = = real patterns = = = = the notion of real patterns has been propounded, notably by philosopher daniel c. dennett, as an intermediate position between strong realism and eliminative materialism. this concept delves into the investigation of patterns observed in scientific phenomena to ascertain whether they signify underlying truths or are mere constructs of human interpretation. dennett provides a unique ontological account concerning real patterns, examining the extent to which these recognized patterns have predictive utility and allow for efficient compression of information. the discourse on real patterns extends beyond philosophical circles, finding relevance in various scientific domains. for example, in biology, inquiries into real patterns seek to elucidate the nature of biological explanations, exploring how recognized patterns contribute to a comprehensive understanding of biological phenomena. similarly, in chemistry, debates around the reality of
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https://en.wikipedia.org/wiki/Philosophy_of_science
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the attenuation of ultrasound waves in photoacoustic and thermoacoustic imaging presents an important drawback in the applicability of these modalities. this issue has been addressed previously in the applied and theoretical literature, and some advances have been made on the topic. in particular, stability inequalities have been proposed for the inverse problem of initial source recovery with partial observations under the assumption of unique determination of the initial pressure. the main goal of this work is to fill this gap, this is, we prove the uniqueness property for the inverse problem and establish the associated stability estimates as well. the problem of reconstructing the initial condition of acoustic waves in the complete - data setting is revisited and a new neumann series reconstruction formula is obtained for the case of partial observations in a semi - bounded geometry. a numerical simulation is also included to test the method.
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arxiv:2101.08615
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in this paper we study the semi - stable reduction of $ p $ and $ p ^ 2 $ - cyclic covers of curves in equal characteristic $ p > 0 $. the main tool we use is the classical artin - schreier - witt theory for $ p ^ n $ - cyclic covers in characteristic $ p $. although the results of this paper concern only the cases of degree $ p $ and $ p ^ 2 $ - cyclic cover we develop the techniques and the framework in which the general cyclic case can be studied.
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arxiv:math/0405529
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efficient key management for automotive networks ( can ) is a critical element, governing the adoption of security in the next generation of vehicles. a recent promising approach for dynamic key agreement between groups of nodes, plug - and - secure for can, has been demonstrated to be information theoretically secure based on the physical properties of the can bus. in this paper, we illustrate side - channel attacks, leading to nearly - complete leakage of the secret key bits, by an adversary that is capable of probing the can bus. we identify the fundamental characteristics that lead to such attacks and propose techniques to minimize the information leakage at the hardware, controller and system levels.
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arxiv:1810.07305
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this short paper proposes to use the statistical analysis of the correlation between dct coefficients to design a new synchronization strategy that can be used for cost - based steganographic schemes in the jpeg domain. first, an analysis is performed on the covariance matrix of dct coefficients of neighboring blocks after a development similar to the one used to generate bossbase. this analysis exhibits groups of uncorrelated coefficients : 4 groups per block and 2 groups of uncorrelated diagonal neighbors together with groups of mutually correlated coefficients groups of 6 coefficients per blocs and 8 coefficients between 2 adjacent blocks. using the uncorrelated groups, an embedding scheme can be designed using only 8 disjoint lattices. the cost map for each lattice is updated firstly by using an implicit underlying gaussian distribution with a variance directly computed from the embedding costs, and secondly by deriving conditional distributions from multivariate distributions. the covariance matrix of these distributions takes into account both the correlations exhibited by the analysis of the covariance matrix and the variance derived from the cost. this synchronization scheme enables to obtain a gain of pe of 5 % at qf 95 for an embedding rate close to 0. 3 bnzac coefficient using dctr feature sets.
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arxiv:2003.10082
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in this article, we describe a function fitting method that has potential applications in machine learning and also prove relevant theorems. the described function fitting method is a convex minimization problem and can be solved using a gradient descent algorithm. we also provide qualitative analysis on fitness to data of this function fitting method. the function fitting problem is also shown to be a solution of a linear, weak partial differential equation ( pde ). we describe a way to fit a sobolev function by giving a method to choose the optimal $ \ lambda $ parameter. we describe a closed - form solution to the derived pde, which enables the parametrization of the solution function. we describe a simple numerical solution using a gradient descent algorithm, that converges uniformly to the actual solution. as the functional of the minimization problem is a quadratic form, there also exists a numerical method using linear algebra. lastly, we give some numerical examples and also numerically demonstrate its application to a binary classification problem.
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arxiv:1811.01336
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we present first results from multi unit spectroscopic explorer ( muse ) observations at the very large telescope in the muse ultra deep field ( mudf ), a $ \ approx 1. 2 \ times 1. 4 $ arcmin $ ^ 2 $ region for which we are collecting $ \ approx $ 200 hours of integral field spectroscopy. the $ \ approx 40 $ - hour observation completed to date reveals the presence of a group of three ly $ \ alpha $ nebulae associated with a bright quasar pair at $ z \ simeq3. 23 $ with projected separation of $ \ approx 500 \ rm ~ kpc $. two of the nebulae are physically associated with the quasars which are likely powering the ly $ \ alpha $ emission, and extend for $ \ gtrsim 100 ~ \ rm kpc $ at a surface brightness level of $ \ approx 6 \ times 10 ^ { - 19 } ~ \ rm erg ~ s ^ { - 1 } ~ cm ^ { - 2 } ~ arcsec ^ { - 2 } $. a third smaller ( $ \ approx $ 35 kpc ) nebula lies at a velocity offset of $ \ approx 1550 $ km s $ ^ { - 1 } $. despite their clustered nature, the two large nebulae have properties similar to those observed in isolated quasars and exhibit no sharp decline in flux at the current depth, suggesting an even more extended distribution of gas around the quasars. we interpret the shape and the alignment of the two brighter nebulae as suggestive of the presence of an extended structure connecting the two quasar host galaxies, as seen for massive galaxies forming within gas - rich filaments in cosmological simulations.
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arxiv:1903.00483
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we conjecture a formula for the schur index of four - dimensional $ \ mathcal { n } = 2 $ theories coupled to $ ( 2, 2 ) $ surface defects in terms of the $ 2d $ - $ 4d $ bps spectrum in the coulomb phase of the theory. the key ingredient in our conjecture is a refined $ 2d $ - $ 4d $ wall - crossing invariant, which we also formulate. our result intertwines recent conjectures expressing the four - dimensional schur index in terms of infrared bps particles, with the cecotti - vafa formula for limits of the elliptic genus in terms of two - dimensional bps solitons. we extend our discussion to framed $ 2d $ - $ 4d $ bps states, and use this to demonstrate a general relationship between surface defect indices and line defect indices. we illustrate our results in the example of $ su ( 2 ) $ super yang - mills coupled to the $ \ mathbb { cp } ^ 1 $ sigma model defect.
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arxiv:1703.02525
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the dynamical density fluctuations around qcd critical point ( cp ) are analyzed using relativistic dissipative fluid dynamics, and we show that the sound mode around the qcd cp is strongly attenuated whereas the thermal fluctuation stands out there. we speculate that if possible suppression or disappearance of a mach cone, which seems to be created by the partonic jets at rhic, is observed as the incident energy of the heavyion collisions is decreased, it can be a signal of the existence of the qcd cp. we have presented the israel - stewart type fluid dynamic equations that are derived rigorously on the basis of the ( dynamical ) renormalization group method in the second part of the talk, which we omit here because of a lack of space.
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arxiv:0907.3388
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we consider the problem of optimizing expensive black - box functions over discrete spaces ( e. g., sets, sequences, graphs ). the key challenge is to select a sequence of combinatorial structures to evaluate, in order to identify high - performing structures as quickly as possible. our main contribution is to introduce and evaluate a new learning - to - search framework for this problem called l2s - disco. the key insight is to employ search procedures guided by control knowledge at each step to select the next structure and to improve the control knowledge as new function evaluations are observed. we provide a concrete instantiation of l2s - disco for local search procedure and empirically evaluate it on diverse real - world benchmarks. results show the efficacy of l2s - disco over state - of - the - art algorithms in solving complex optimization problems.
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arxiv:2012.07320
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this paper generalizes former works of derksen, weyman and zelevinsky about quivers with potentials. we consider semisimple finite - dimensional algebras $ e $ over a field $ f $, such that $ e \ otimes _ { f } e ^ { op } $ is semisimple. we assume that $ e $ contains a certain type of $ f $ - basis which is a generalization of a multiplicative basis. we study potentials belonging to the algebra of formal power series, with coefficients in the tensor algebra over $ e $, of any finite - dimensional $ e $ - $ e $ - bimodule on which $ f $ acts centrally. in this case, we introduce a cyclic derivative and to each potential we associate a jacobian ideal. finally, we develop a mutation theory of potentials, which in the case that the bimodule is $ z $ - free, it behaves as the quiver case ; but allows us to obtain realizations of a certain class of skew - symmetrizable integer matrices.
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arxiv:1506.05880
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we discuss the influence on spin - fluctuation pairing theory of orbital selective strong correlation effects in fe - based superconductors, particularly fe chalcogenide systems. we propose that a key ingredient for an improved itinerant pairing theory is orbital selectivity, i. e., incorporating the reduced coherence of quasiparticles occupying specific orbital states. this modifies the usual spin - fluctuation via suppression of pair scattering processes involving those less coherent states and results in orbital selective cooper pairing of electrons in the remaining states. we show that this paradigm yields remarkably good agreement with the experimentally observed anisotropic gap structures in both bulk and monolayer fese, as well as lifeas, indicating that orbital selective cooper pairing plays a key role in the more strongly correlated iron - based superconductors.
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arxiv:1611.02643
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given two non - empty subsets $ w, w ' \ subseteq g $ in an arbitrary abelian group $ g $, $ w ' $ is said to be an additive complement to $ w $ if $ w + w ' = g $ and it is minimal if no proper subset of $ w ' $ is a complement to $ w $. the notion was introduced by nathanson and previous work by him, chen - - yang, kiss - - s \ ` andor - - yang etc. focussed on $ g = \ mathbb { z } $. in the higher rank case, recent work by the authors treated a class of subsets, namely the eventually periodic sets. however, for infinite subsets, not of the above type, the question of existence or inexistence of minimal complements is open. in this article, we study subsets which are not eventually periodic. we introduce the notion of " spiked subsets " and give necessary and sufficient conditions for the existence of minimal complements for them. this provides a partial answer to a problem of nathanson.
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arxiv:1902.01363
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we examine the consequences of lorentz violation during slow - roll inflation. we consider a canonical scalar inflaton coupled, through its potential, to the divergence of a fixed - norm timelike vector field, or " aether. " the vector is described by einstein - aether theory, a vector - tensor model of gravitational lorentz violation. we derive and analyze the cosmological perturbation equations for the metric, inflaton, and aether. if the scale of lorentz violation is sufficiently small compared to the planck mass, and the strength of the scalar - aether coupling is suitably large, then the spin - 0 and spin - 1 perturbations grow exponentially and spoil the inflationary background. the effects of such a coupling on the cmb are too small to be visible to current or near - future cmb experiments ; unusually, no isocurvature modes are produced at first order in a perturbative expansion around the aether norm. these results are discussed for both a general potential and a worked example, $ m ^ 2 \ phi ^ 2 $ inflation with a quadratic scalar - aether coupling term.
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arxiv:1309.4778
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we investigate the evolution of high redshift seed black hole masses at late times and their observational signatures. the massive black hole seeds studied here form at extremely high redshifts from the direct collapse of pre - galactic gas discs. populating dark matter halos with seeds formed in this way, we follow the mass assembly of these black holes to the present time using a monte - carlo merger tree. using this machinery we predict the black hole mass function at high redshifts and at the present time ; the integrated mass density of black holes and the luminosity function of accreting black holes as a function of redshift. these predictions are made for a set of three seed models with varying black hole formation efficiency. given the accuracy of current observational constraints, all 3 models can be adequately fit. discrimination between the models appears predominantly at the low mass end of the present day black hole mass function which is not observationally well constrained. however, all our models predict that low surface brightness, bulgeless galaxies with large discs are least likely to be sites for the formation of massive seed black holes at high redshifts. the efficiency of seed formation at high redshifts has a direct influence on the black hole occupation fraction in galaxies at z = 0. this effect is more pronounced for low mass galaxies. this is the key discriminant between the models studied here and the population iii remnant seed model. we find that there exists a population of low mass galaxies that do not host nuclear black holes. our prediction of the shape of the black hole mass - velocity dispersion relation at the low mass end is in agreement with the recent observational determination from the census of low mass galaxies in the virgo cluster.
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arxiv:0709.0529
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numerous phenomenological nuclear models have been proposed to describe specific observables within different regions of the nuclear chart. however, developing a unified model that describes the complex behavior of all nuclei remains an open challenge. here, we explore whether novel symbolic machine learning ( ml ) can rediscover traditional nuclear physics models or identify alternatives with improved simplicity, fidelity, and predictive power. to address this challenge, we developed a multi - objective iterated symbolic regression approach that handles symbolic regressions over multiple target observables, accounts for experimental uncertainties and is robust against high - dimensional problems. as a proof of principle, we applied this method to describe the nuclear binding energies and charge radii of light and medium mass nuclei. our approach identified simple analytical relationships based on the number of protons and neutrons, providing interpretable models with precision comparable to state - of - the - art nuclear models. additionally, we integrated this ml - discovered model with an existing complementary model to estimate the limits of nuclear stability. these results highlight the potential of symbolic ml to develop accurate nuclear models and guide our description of complex many - body problems.
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arxiv:2404.11477
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we consider the nearest - neighbor spacing distributions of mixed random matrix ensembles interpolating between different symmetry classes, or between integrable and non - integrable systems. we derive analytical formulas for the spacing distributions of 2x2 or 4x4 matrices and show numerically that they provide very good approximations for those of random matrices with large dimension. this generalizes the wigner surmise, which is valid for pure ensembles that are recovered as limits of the mixed ensembles. we show how the coupling parameters of small and large matrices must be matched depending on the local eigenvalue density.
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arxiv:1202.3925
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in this letter we explore the potential of probing new light force - carriers, with spin - independent couplings to the electron and the neutron, using precision isotope shift spectroscopy. we develop a formalism to interpret linear king plots as bounds on new physics with minimal theory inputs. we focus only on bounding the new physics contributions that can be calculated independently of the standard model nuclear effects. we apply our method to existing ca + data and project its sensitivity to possibly existing new bosons using narrow transitions in other atoms and ions ( specifically, sr and yb ). future measurements are expected to improve the relative precision by five orders of magnitude, and can potentially lead to an unprecedented sensitivity for bosons within the 10 kev to 10 mev mass range.
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arxiv:1704.05068
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the qcd axion solves the strong cp problem and represents an attractive particle candidate for cold dark matter ( cdm ). however, quantum fluctuations of the axion field during inflation easily result in large cdm isocurvature perturbations that are in conflict with observations of the cosmic microwave background ( cmb ). in this paper, we demonstrate how this problem can be solved in low - scale models of hybrid inflation that may emerge from supersymmetric grand unified theories. we consider both f - term hybrid inflation ( fhi ) and d - term hybrid inflation ( dhi ) in supergravity, explicitly taking into account the effect of hidden - sector supersymmetry breaking. we discuss the production of cosmic strings and show how the soft terms in the scalar potential readily allow to achieve the correct scalar spectral index. in both cases, we are able to identify large regions in parameter space that are consistent with all constraints. in particular, we find that evading the cdm isocurvature constraint always requires a small yukawa or gauge coupling of o ( 10 ^ - 3 ) or smaller. this translates into upper bounds on the gravitino mass of o ( 10 ^ 5 ) gev in fhi and o ( 10 ^ 9 ) gev in dhi. our results point to interesting scenarios in well - motivated parameter regions that will be tested in future axion and cmb experiments.
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arxiv:1806.06056
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we prove that the symmetric group $ s _ n $ is the smallest non - cyclic quotient of the braid group $ b _ n $ for $ n = 5, 6 $ and that the alternating group $ a _ n $ is the smallest non - trivial quotient of the commutator subgroup $ b _ n ' $ for $ n = 5, 6, 7, 8 $. we also give an improved lower bound on the order of any non - cyclic quotient of $ b _ n $.
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arxiv:2009.10139
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let $ t ( f ) = f * k $, where $ k $ is a product kernel or a flag kernel on a direct product of graded lie groups $ g = g _ 1 \ times \ cdots \ times g _ { \ nu } $. suppose $ t $ is invertible on $ l ^ 2 ( g ) $. we prove that its inverse is given by $ t ^ { - 1 } ( g ) = g * l $, where $ l $ is a product kernel or a flag kernel accordingly.
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arxiv:2305.00914
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let $ m $ be a compact connected oriented $ n - 1 $ dimensional manifold without boundary. in this work, shape space is the orbifold of unparametrized immersions from $ m $ to $ \ mathbb r ^ n $. the results of \ cite { michor118 }, where mean curvature weighted metrics were studied, suggest incorporating gau { \ ss } curvature weights in the definition of the metric. this leads us to study metrics on shape space that are induced by metrics on the space of immersions of the form $ $ g _ f ( h, k ) = \ int _ { m } \ phi. \ bar g ( h, k ) \ vol ( f ^ * \ bar { g } ). $ $ here $ f \ in \ imm ( m, \ r ^ n ) $ is an immersion of $ m $ into $ \ r ^ n $ and $ h, k \ in c ^ \ infty ( m, \ mathbb r ^ n ) $ are tangent vectors at $ f $. $ \ bar g $ is the standard metric on $ \ mathbb r ^ n $, $ f ^ * \ bar g $ is the induced metric on $ m $, $ \ vol ( f ^ * \ bar g ) $ is the induced volume density and $ \ phi $ is a suitable smooth function depending on the mean curvature and gau { \ ss } curvature. for these metrics we compute the geodesic equations both on the space of immersions and on shape space and the conserved momenta arising from the obvious symmetries. numerical experiments illustrate the behavior of these metrics.
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arxiv:1102.0678
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observations suggested that the occurrence rate of hot jupiters ( hjs ) in open clusters is largely consistent with the field ( $ \ sim1 \ % $ ) but in the binary - rich cluster m67, the rate is $ \ sim5 \ % $. how does the cluster environment boost hj formation via the high - eccentricity tidal migration initiated by the extreme - amplitude von zeipel - lidov - kozai ( xzkl ) mechanism forced by a companion star? our analytical treatment shows that the cluster ' s collective gravitational potential alters the companion ' s orbit slowly, which may render the star - planet - companion configuration xzkl - favourable, a phenomenon only possible for very wide binaries. we have also performed direct gyr $ n $ - body simulations of the star cluster evolution and xzkl of planets ' orbit around member stars. we find that an initially - single star may acquire a companion star via stellar scattering and the companion may enable xzkl in the planets ' orbit. planets around an initially - binary star may also be xzkl - activated by the companion. in both scenarios, the companion ' s orbit has likely been significantly changed by star scattering and the cluster potential before xzkl occurs in the planets ' orbits. across different cluster models, 0. 8 \ % - 3 \ % of the planets orbiting initially - single stars have experienced xzkl while the fraction is 2 \ % - 26 \ % for initially - binary stars. notably, the ejection fraction is similar to or appreciably smaller than xzkl. around a star that is binary at 1 gyr, 13 \ % - 32 \ % of its planets have undergone xzkl, and combined with single stars, the overall xzkl fraction is 3 \ % - 21 \ %, most affected by the cluster binarity. if 10 \ % of the stars in m67 host a giant planet, our model predicts an hj occurrence rate of $ \ sim1 \ % $. we suggest that hj surveys target old, high - binarity, not - too - dense open clusters and prioritise wide binaries to maximise hj yield.
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arxiv:2306.15966
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this paper studies eight families of infinite series involving hyperbolic functions. under some conditions, these series are linear combinations of derivatives of eisenstein series. the paper gives a systematic method for computing the values of these series at cm points. the approach utilizes complex multiplication theory, the structure of the rings of modular forms and quasimodular forms, and certain differential operators defined on these rings. this paper also expresses the generalized reciprocal sums of fibonacci numbers as the special values of the series mentioned above. thus it gives some algebraic independence results about the generalized reciprocal sums of fibonacci numbers.
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arxiv:2312.16929
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in this paper we study intertwining functors ( radon transforms ) for twisted d - modules on partial flag varieties and their relation to the representations of semisimple lie algebras. we show that certain intertwining functors give equivalences of derived categories of twisted d - modules. this is a generalization of a result by marastoni. we also show that these intertwining functors from dominant to antidominant direction are compatible with taking global sections.
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arxiv:1701.02655
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the functional equation f ( p ( z ) ) = g ( q ( z ) ) is studied, where p, q are polynomials and f, g are trancendental meromorphic functions in c. we find all the pairs p, q for which there exist nonconstant f, g satisfying our equation and there exist no rational f, g with this property. in fact, a more general problem is solved. in addition to algebraic methods, some results from local analytic dynamics are used.
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arxiv:math/9606217
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over a hundred rocky planets orbiting sun - like stars in very short orbital periods ( < 1 day ) have been discovered by the kepler mission. these planets, known as ultra - short - period ( usp ) planets, are unlikely to have attained their orbits in situ. instead, they must have migrated in. here we propose that these planets reach their current orbits by high - eccentricity migration. in a scaled - down version of the dynamics that may have been experienced by their high mass analog, the hot jupiters, these planets reach high eccentricities via chaotic secular interactions with their companion planets and then undergo orbital circularization due to dissipation of tides raised on the planet. this proposal is motivated by the following observations : planetary systems observed by kepler often contain several super - earths with non - negligible eccentricities and inclinations, and possibly extending beyond au distances ; while only a small fraction of usp planets have known transiting companions, and none closely spaced, we argue that most of them should have companions at periods of ~ 10 - 50 days. the outer sibling planets, through secular chaos, can remove angular momentum from the inner most planet, originally at periods of ~ 5 - 10 days. when the latter reaches an eccentricity higher than 0. 8, it is tidally captured by the central star and becomes an usp planet. this scenario naturally explains the observation that most usp planets have significantly more distant transiting companions compared to their counterparts at slightly longer periods ( 1 - 3 days ), a feature un - accounted for in other proposed scenarios. our model also predicts that usp planets should have : ( i ) spin - orbit angles, and inclinations relative to outer planets, in the range of ~ 10 - 50 degrees ; ( ii ) several outer planetary companions extending to beyond au distances, both of which may be tested by tess and its follow - up observations.
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arxiv:1804.05065
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in this paper, we study the mach reflection phenomenon in inviscid flows using a higher order discontinuous galerkin method and overset grids. we use the shock capturing procedure proposed in siva prasad kochi et al. using overset grids to capture the discontinuities occurring in the supersonic flow over a wedge accurately. in this procedure, we obtain a coarse grid solution first and using the troubled cell data, we construct an overset grid which is approximately aligned to all the discontinuities. we rerun the solver with the coarse grid solution as the initial condition while using the troubled cell indicator and the limiter only on the overset grid. this allows us to capture the discontinuities accurately. using this procedure, we have obtained the solution for mach $ 3. 0 $ and $ 4. 0 $ flow over a wedge for various wedge angles and determined the detachment criterion and the von neumann condition accurately. we have also determined the mach stem height for various wedge angles for these mach numbers. we have also demonstrated the hysteresis that occurs in the transition from regular reflection to mach reflection.
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arxiv:2301.04309
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phylodynamics is an area of population genetics that uses genetic sequence data to estimate past population dynamics. modern state - of - the - art bayesian nonparametric methods for recovering population size trajectories of unknown form use either change - point models or gaussian process priors. change - point models suffer from computational issues when the number of change - points is unknown and needs to be estimated. gaussian process - based methods lack local adaptivity and cannot accurately recover trajectories that exhibit features such as abrupt changes in trend or varying levels of smoothness. we propose a novel, locally - adaptive approach to bayesian nonparametric phylodynamic inference that has the flexibility to accommodate a large class of functional behaviors. local adaptivity results from modeling the log - transformed effective population size a priori as a horseshoe markov random field, a recently proposed statistical model that blends together the best properties of the change - point and gaussian process modeling paradigms. we use simulated data to assess model performance, and find that our proposed method results in reduced bias and increased precision when compared to contemporary methods. we also use our models to reconstruct past changes in genetic diversity of human hepatitis c virus in egypt and to estimate population size changes of ancient and modern steppe bison. these analyses show that our new method captures features of the population size trajectories that were missed by the state - of - the - art methods.
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arxiv:1808.04401
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the region near the galactic center may have experienced recurrent episodes of injection of energy in excess of $ \ sim $ 10 $ ^ { 55 } $ ergs due to repeated starbursts involving more than $ \ sim $ 10 $ ^ 4 $ supernovae. this hypothesis can be tested by measurements of $ \ gamma $ - ray lines produced by the decay of radioactive isotopes and positron annihilation, or by searches for pulsars produced during starbursts. recent osse observations of 511 kev emission extending above the galactic center led to the suggestion of a starburst driven fountain from the galactic center. we present egret observations that might support this picture.
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arxiv:astro-ph/9709029
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we demonstrate a 10 - ghz bandwidth digitizer with 7 - effective bits of resolution and 52db sfdr, using photonic time stretch technique. to the best of our knowledge, this is the highest resolution analog - to - digital converter ( adc ) of the same bandwidth, with at least an order of magnitude higher snr than previously achieved. this is made possible by correction of distortion due to time warps, and non - linearities due to wavelength dependent bias variation in the mach - zehnder modulator. we also demonstrate concatenation of 30 wavelength interleaved time segments with high fidelity on the path to achieving continuous time operation.
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arxiv:0807.0349
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we study the electroweak phase transition in an effective 3 - dimensional theory for a higgs mass of about 70 gev by monte carlo simulations. the transition temperature and jumps of order parameters are obtained and extrapolated to the continuum using multi - histogram techniques and finite size analysis.
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arxiv:hep-lat/9607062
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we characterize 1 - complemented subspaces of finite codimension in strictly monotone one - $ p $ - convex, $ 2 < p < \ infty, $ sequence spaces. next we describe, up to isometric isomorphism, all possible types of 1 - unconditional structures in sequence spaces with few surjective isometries. we also give a new example of a class of real sequence spaces with few surjective isometries.
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arxiv:math/9403207
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electricity production currently generates approximately 25 % of greenhouse gas emissions in the usa. thus, increasing the amount of renewable energy is a key step to carbon neutrality. however, integrating a large amount of fluctuating renewable generation is a significant challenge for power grid operating and planning. grid reliability, i. e., an ability to meet operational constraints under power fluctuations, is probably the most important of them. in this paper, we propose computationally efficient and accurate methods to estimate the probability of failure, i. e. reliability constraints violation, under a known distribution of renewable energy generation. to this end, we investigate an importance sampling approach, a flexible extension of monte - carlo methods, which adaptively changes the sampling distribution to generate more samples near the reliability boundary. the approach allows to estimate failure probability in real - time based only on a few dozens of random samples, compared to thousands required by the plain monte - carlo. our study focuses on high voltage direct current power transmission grids with linear reliability constraints on power injections and line currents. we propose a novel theoretically justified physics - informed adaptive importance sampling algorithm and compare its performance to state - of - the - art methods on multiple ieee power grid test cases.
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arxiv:2105.08753
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when a quantum emitter ( qe ) is placed in close proximity to a plasmonic metal nanoparticle ( mnp ) within an external optical field, a dipole - dipole coupling arises, resulting in a highly tunable hybrid nanosystem that surpasses the optical manipulation capabilities of the individual components. these hybrid systems enable the exploration and manipulation of optical fields at the intersection between classical and quantum phenomena. theoretical models of this interaction have typically been limited to the extreme orientations, where the qe and plasmonic dipoles are polarised either along or perpendicular to the inter - particle axis, for analytical tractability. in this work, we generalise the semi - classical optical dipole - dipole interaction model for a two - level quantum emitter in a plasmonic field for arbitrary polarisation angles. we show that the total field experienced by the quantum emitter at intermediate angles does not necessarily align with the external input field and discuss the implications of varying the polarisation angle of the external input field.
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arxiv:2412.07085
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understanding how perception and action deal with sensorimotor conflicts, such as the rubber - hand illusion ( rhi ), is essential to understand how the body adapts to uncertain situations. recent results in humans have shown that the rhi not only produces a change in the perceived arm location, but also causes involuntary forces. here, we describe a deep active inference agent in a virtual environment, which we subjected to the rhi, that is able to account for these results. we show that our model, which deals with visual high - dimensional inputs, produces similar perceptual and force patterns to those found in humans.
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arxiv:2008.07408
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the common features in the raman data of high temperature superconductors : ( the cuprates, bismathates, alkali doped fullerides and some organic superconductors ), are analyzed. it was shown that qualitative understanding of the data can be achieved in terms of non - fermi liquid models for their normal state, with appropiate bag mechanisms for the superconducting state.
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arxiv:cond-mat/9602111
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in recent years, network models have gained prominence for their ability to capture complex associations. in statistical omics, networks can be used to model and study the functional relationships between genes, proteins, and other types of omics data. if a gaussian graphical model is assumed, a gene association network can be determined from the non - zero entries of the inverse covariance matrix of the data. due to the high - dimensional nature of such problems, integrative methods that leverage similarities between multiple graphical structures have become increasingly popular. the joint graphical lasso is a powerful tool for this purpose, however, the current aic - based selection criterion used to tune the network sparsities and similarities leads to poor performance in high - dimensional settings. we propose stabjgl, which equips the joint graphical lasso with a stable and accurate penalty parameter selection approach that combines the notion of model stability with likelihood - based similarity selection. the resulting method makes the powerful joint graphical lasso available for use in omics settings, and outperforms the standard joint graphical lasso, as well as state - of - the - art joint methods, in terms of all performance measures we consider. applying stabjgl to proteomic data from a pan - cancer study, we demonstrate the potential for novel discoveries the method brings. a user - friendly r package for stabjgl with tutorials is available on github at https : / / github. com / camiling / stabjgl.
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arxiv:2306.03212
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in this paper, we introduce a subclass of close - to - convex functions defined in the open unit disk. we obtain the inclusion relationships, coefficient estimates and fekete - szego inequality. the results presented here would provide extension of those given in earlier works.
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arxiv:1606.00099
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we report the results of a search for flavor - changing neutral current, lepton - flavor, and lepton - number violating decays of the 3 and 4 - body decay modes of d0 ( and its antiparticle ) containing muons and electrons. using data from fermilab charm hadroproduction experiment e791, we examine modes with two leptons and either a rho ( 0 ), kstar, or phi vector meson or a non - resonant pi pi, k pi, or k k pair of pseudoscalar mesons. no evidence for any of these decays is found. therefore, we present branching - fraction upper limits at 90 % confidence level for the 27 decay modes examined ( 18 new ).
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arxiv:hep-ex/0011077
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optically excited electron - hole pairs, driven by a strong terahertz ( thz ) field, create high - sidebands in the optical spectrum. the sideband spectrum exhibits a ' plateau ' up to a cutoff of 3. 17up, where up is the ponderomotive energy. this cutoff is determined, semi - classically, from the maximum kinetic energy an electron - hole pair can gain from the thz field along a closed trajectory. a full quantum treatment reveals a second, classically forbidden, plateau with a cutoff of 8up, the maximum kinetic energy an electron - hole pair can gain from the thz field along an open trajectory. the second plateau appears because a spatially separated electron and hole can still recombine if the classical excursion is within the coherence length of the electron - hole wavefunction or, equivalently, the coherence time is longer than the excursion time ( half the thz field period ). this effect broadens the range of materials and excitation conditions where high - sideband generations can occur, thereby providing a wealth of novel systems for ultrafast electro - optical applications.
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arxiv:1311.6237
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we used the internal conversion ( $ e _ 0 $ transition ) of germanium - 72 to indirectly measure the low energy nuclear recoils of germanium. together with a reliable monte carlo package, in which we implement the internal conversion process, the data was compared to the lindhard ( $ k $ = 0. 159 ) and barker - mei models. a shape analysis indicates that both models agree well with data in the region of interest within 4 %. the most probable value ( mpv ) of the nuclear recoils obtained from the shape analysis is 17. 5 kev with an average path - length of 0. 014 $ \ mu $ m.
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arxiv:1304.6773
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we construct a large family of exact solutions to the hyperbolic system of 3 equations of ideal granular hydrodynamics in several dimensions for arbitrary adiabatic index $ \ gamma $. in dependence of initial conditions these solutions can keep smoothness for all times or develop singularity. in particular, in the 2d case the singularity can be formed either in a point or along a line. for $ \ gamma = - 1 $ the problem is reduced to the system of two equations, related to a special case of the chaplygin gas. in the 1d case this system can be written in the riemann invariant and can be treated in a standard way. the solution to the riemann problem in this case demonstrate an unusual and complicated behavior.
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arxiv:1302.1301
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we consider the galerkin method for approximating the spectrum of an operator $ t + a $ where $ t $ is semi - bounded self - adjoint and $ a $ satisfies a relative compactness condition. we show that the method is reliable in all regions where it is reliable for the unperturbed problem - which always contains $ \ mathbb { c } \ backslash \ mathbb { r } $. the results lead to a new technique for identifying eigenvalues of $ t $, and for identifying spectral pollution which arises from applying the galerkin method directly to $ t $. the new technique benefits from being applicable on the form domain.
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arxiv:1309.0232
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be viewed as an ever - changing iterative process rather than a fixed set of steps. most research begins with a general statement of the problem, or rather, the purpose for engaging in the study. the literature review identifies flaws or holes in previous research which provides justification for the study. often, a literature review is conducted in a given subject area before a research question is identified. a gap in the current literature, as identified by a researcher, then engenders a research question. the research question may be parallel to the hypothesis. the hypothesis is the supposition to be tested. the researcher ( s ) collects data to test the hypothesis. the researcher ( s ) then analyzes and interprets the data via a variety of statistical methods, engaging in what is known as empirical research. the results of the data analysis in rejecting or failing to reject the null hypothesis are then reported and evaluated. at the end, the researcher may discuss avenues for further research. however, some researchers advocate for the reverse approach : starting with articulating findings and discussion of them, moving " up " to identification of a research problem that emerges in the findings and literature review. the reverse approach is justified by the transactional nature of the research endeavor where research inquiry, research questions, research method, relevant research literature, and so on are not fully known until the findings have fully emerged and been interpreted. rudolph rummel says, "... no researcher should accept any one or two tests as definitive. it is only when a range of tests are consistent over many kinds of data, researchers, and methods can one have confidence in the results. " plato in meno talks about an inherent difficulty, if not a paradox, of doing research that can be paraphrased in the following way, " if you know what you ' re searching for, why do you search for it?! [ i. e., you have already found it ] if you don ' t know what you ' re searching for, what are you searching for?! " = = research methods = = the goal of the research process is to produce new knowledge or deepen understanding of a topic or issue. this process takes three main forms ( although, as previously discussed, the boundaries between them may be obscure ) : exploratory research, which helps to identify and define a problem or question. constructive research, which tests theories and proposes solutions to a problem or question. empirical research, which tests the feasibility of a solution using empirical evidence. there are two major types of empirical
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https://en.wikipedia.org/wiki/Research
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a turbulent flow is maintained by an external supply of kinetic energy, which is eventually dissipated into heat at steep velocity gradients. the scale at which energy is supplied greatly differs from the scale at which energy is dissipated, the more so as the turbulent intensity ( the reynolds number ) is larger. the resulting energy flux over the range of scales, intermediate between energy injection and dissipation, acts as a source of time irreversibility. as it is now possible to follow accurately fluid particles in a turbulent flow field, both from laboratory experiments and from numerical simulations, a natural question arises : how do we detect time irreversibility from these lagrangian data? here we discuss recent results concerning this problem. for lagrangian statistics involving more than one fluid particle, the distance between fluid particles introduces an intrinsic length scale into the problem. the evolution of quantities dependent on the relative motion between these fluid particles, including the kinetic energy in the relative motion, or the configuration of an initially isotropic structure can be related to the equal - time correlation functions of the velocity field, and is therefore sensitive to the energy flux through scales, hence to the irreversibility of the flow. in contrast, for single - particle lagrangian statistics, the most often studied velocity structure functions cannot distinguish the " arrow of time. " recent observations from experimental and numerical simulation data, however, show that the change of kinetic energy following the particle motion, is sensitive to time - reversal. we end the survey with a brief discussion of the implication of this line of work.
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arxiv:1506.08734
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sparse regression algorithms have been proposed as the appropriate framework to model the governing equations of a system from data, without needing prior knowledge of the underlying physics. in this work, we use sparse regression to build an accurate and explainable model of the stellar mass of central galaxies given properties of their host dark matter ( dm ) halo. our data set comprises 9, 521 central galaxies from the eagle hydrodynamic simulation. by matching the host halos to a dm - only simulation, we collect the halo mass and specific angular momentum at present time and for their main progenitors in 10 redshift bins from $ z = 0 $ to $ z = 4 $. the principal component of our governing equation is a third - order polynomial of the host halo mass, which models the stellar - mass halo - mass relation. the scatter about this relation is driven by the halo mass evolution and is captured by second and third - order correlations of the halo mass evolution with the present halo mass. an advantage of sparse regression approaches is that unnecessary terms are removed. although we include information on halo specific angular momentum, these parameters are discarded by our methodology. this suggests that halo angular momentum has little connection to galaxy formation efficiency. our model has a root mean square error ( rmse ) of $ 0. 167 \ log _ { 10 } ( m ^ * / m _ \ odot ) $, and accurately reproduces both the stellar mass function and central galaxy correlation function of eagle. the methodology appears to be an encouraging approach for populating the halos of dm - only simulations with galaxies, and we discuss the next steps that are required.
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arxiv:2101.02986
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we present dependent javascript ( djs ), a statically - typed dialect of the imperative, object - oriented, dynamic language. djs supports the particularly challenging features such as run - time type - tests, higher - order functions, extensible objects, prototype inheritance, and arrays through a combination of nested refinement types, strong updates to the heap, and heap unrolling to precisely track prototype hierarchies. with our implementation of djs, we demonstrate that the type system is expressive enough to reason about a variety of tricky idioms found in small examples drawn from several sources, including the popular book javascript : the good parts and the sunspider benchmark suite.
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arxiv:1112.4106
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charm and beauty are heavy quarks with observed masses of 1. 28 gev / $ \ textit { c } ^ 2 $ and 4. 18 gev / $ \ textit { c } ^ 2 $ respectively. they are produced in initial hard scattering processes. due to their small formation time ( $ \ delta t \ sim0. 1 fm / \ textit { c } $ ) as compared to the formation time of qgp ( $ \ delta t \ sim0. 3 fm / \ textit { c } $ ) at the lhc, they experience all the stages occuring during the time evolution of the hot and dense medium produced in heavy - ion collisions. therefore, the measurement of open charm and beauty production allows probing qgp properties and investigating the color charge and mass dependence of the parton in - medium energy loss. moreover, due to their large masses ( $ m _ c, m _ b \ gg \ lambda _ { qcd } $ ) their pp production cross - sections are calculable within the domain of perturbative qcd constituting an excellent test of pqcd calculations. the aim of this study is to understand the processes involved in the production of charm quarks through the productions of d $ ^ + $, d $ ^ 0 $, d $ ^ + _ s $ and $ \ lambda _ c ^ + $ hadrons. further to investigate the possibility of hadronization of the charm quarks, ratios like $ \ lambda _ c ^ + $ / $ d ^ + $, $ d _ s ^ + $ / $ d ^ + $, $ \ lambda _ c ^ + $ / $ d ^ 0 $ and $ d _ s ^ + $ / $ d ^ 0 $ are also measured. for the current analysis, the events are generated by using pythia 8 for pp collisions at $ \ sqrt { s } $ = 13 tev. pythia 8 has proved to be quite successful in explaining the heavy - flavor particle production at the lhc energies.
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arxiv:2108.09965
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we investigate the relevance of kinematically identified bulges, discs and their role relative to galaxy quenching. we utilize an analysis of the sdss - manga survey conducted with the gpu - based code bang which simultaneously models galaxy photometry and kinematics to decompose galaxies into their structural components. below m ~ 1011 msun, galaxies exhibit a wide range of dynamical properties, determined by the relative prominence of a dispersion - supported inner region and a rotationally - supported disc. our analysis reveals a natural separation between these classes, with only a minor fraction of stellar mass retained by structures exhibiting intermediate dynamical support. when examining galaxies in terms of their star formation activity, an apparent decrease in rotational support is observed as they move below the star - forming main sequence. this behaviour is evident with luminosity - weighted tracers of kinematics, while it almost vanishes with mass - weighted tracers. luminosity - weighted quantities not only capture differences in kinematics but also in the stellar population, potentially leading to biased interpretations of galaxy dynamical properties and quenching. our findings suggest that quenching does not imply almost any structural transformation in galaxies below m ~ 10 ^ 11 msun. processes as disc fading more likely account for observed differences in mass - weighted and luminosity - weighted galaxy properties ; when the galactic disc ceases star formation, its mass - to - light ratio grows without any significant morphological transformation. the picture is remarkably different above m ~ 10 ^ 11 msun. regardless of the tracer used, a substantial increase in galaxy dispersion support is observed along with a significant structural change. a different quenching mechanism, most likely associated with mergers, dominates. notably, this mechanism is confined to a very limited range of high masses.
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arxiv:2403.09812
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we propose a novel multibody dynamics simulation framework that can efficiently deal with large - dimensionality and complementarity multi - contact conditions. typical contact simulation approaches perform contact impulse - level fixed - point iteration ( il - fpi ), which has high time - complexity from large - size matrix inversion and multiplication, as well as susceptibility to ill - conditioned contact situations. to circumvent this, we propose a novel framework based on velocity - level fixed - point iteration ( vl - fpi ), which, by utilizing a certain surrogate dynamics and contact nodalization ( with virtual nodes ), can achieve not only inter - contact decoupling but also their inter - axes decoupling ( i. e., contact diagonalization ). this then enables us to one - shot / parallel - solve the contact problem during each vl - fpi iteration - loop, while the surrogate dynamics structure allows us to circumvent large - size / dense matrix inversion / multiplication, thereby, significantly speeding up the simulation time with improved convergence property. we theoretically show that the solution of our framework is consistent with that of the original problem and, further, elucidate mathematical conditions for the convergence of our proposed solver. performance and properties of our proposed simulation framework are also demonstrated and experimentally - validated for various large - dimensional / multi - contact scenarios including deformable objects.
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arxiv:2201.09212
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we consider the hamiltonian and lagrangian embedding of a first - order, massive spin - one, gauge non - invariant theory involving anti - symmetric tensor field. we apply the bfv - brst generalised canonical approach to convert the model to a first class system and construct nil - potent bfv - brst charge and an unitarising hamiltonian. the canonical analysis of the st \ " uckelberg formulation of this model is presented. we bring out the contrasting feature in the constraint structure, specifically with respect to the reducibility aspect, of the hamiltonian and the lagrangian embedded model. we show that to obtain manifestly covariant st \ " uckelberg lagrangian from the bfv embedded hamiltonian, phase space has to be further enlarged and show how the reducible gauge structure emerges in the embedded model.
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arxiv:hep-th/0104107
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traditional neural networks assume vectorial inputs as the network is arranged as layers of single line of computing units called neurons. this special structure requires the non - vectorial inputs such as matrices to be converted into vectors. this process can be problematic. firstly, the spatial information among elements of the data may be lost during vectorisation. secondly, the solution space becomes very large which demands very special treatments to the network parameters and high computational cost. to address these issues, we propose matrix neural networks ( matnet ), which takes matrices directly as inputs. each neuron senses summarised information through bilinear mapping from lower layer units in exactly the same way as the classic feed forward neural networks. under this structure, back prorogation and gradient descent combination can be utilised to obtain network parameters efficiently. furthermore, it can be conveniently extended for multimodal inputs. we apply matnet to mnist handwritten digits classification and image super resolution tasks to show its effectiveness. without too much tweaking matnet achieves comparable performance as the state - of - the - art methods in both tasks with considerably reduced complexity.
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arxiv:1601.03805
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we review some recent experimental and theoretical work on the correlation among hadrons produced at intermediate $ p _ t $ at rhic. the topics include : forward and backward asymmetry with and without trigger at mid - rapidity, associated - particle distribution on the near side, the $ \ omega $ puzzle and its solution, associated particles on the away side, and two - jet recombination at lhc.
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arxiv:nucl-th/0701051
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an attempt had been made to get algebraic structure of 2d complex harmonic oscillator.
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arxiv:1107.3301
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a recently discovered classical - quantum correspondence ( cqc ) maps certain quantum problems to corresponding classical problems. we illustrate the cqc for a quantum scalar field in the gravitational background of a collapsing spherical shell. by truncating the problem to a small set of variables, we show how the cqc can yield hawking radiation as well as the slow down of the collapse due to radiation backreaction.
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arxiv:1803.08919
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a pervasive design issue of ai systems is their explainability - - how to provide appropriate information to help users understand the ai. the technical field of explainable ai ( xai ) has produced a rich toolbox of techniques. designers are now tasked with the challenges of how to select the most suitable xai techniques and translate them into ux solutions. informed by our previous work studying design challenges around xai ux, this work proposes a design process to tackle these challenges. we review our and related prior work to identify requirements that the process should fulfill, and accordingly, propose a question - driven design process that grounds the user needs, choices of xai techniques, design, and evaluation of xai ux all in the user questions. we provide a mapping guide between prototypical user questions and exemplars of xai techniques to reframe the technical space of xai, also serving as boundary objects to support collaboration between designers and ai engineers. we demonstrate it with a use case of designing xai for healthcare adverse events prediction, and discuss lessons learned for tackling design challenges of ai systems.
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arxiv:2104.03483
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a highly - asymmetric " psi ' ' factory " may be the best approach for studying d0 anti - d0 mixing.
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arxiv:hep-ex/0111043
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speaker anonymization is the task of modifying a speech recording such that the original speaker cannot be identified anymore. since the first voice privacy challenge in 2020, along with the release of a framework, the popularity of this research topic is continually increasing. however, the comparison and combination of different anonymization approaches remains challenging due to the complexity of evaluation and the absence of user - friendly research frameworks. we therefore propose an efficient speaker anonymization and evaluation framework based on a modular and easily extendable structure, almost fully in python. the framework facilitates the orchestration of several anonymization approaches in parallel and allows for interfacing between different techniques. furthermore, we propose modifications to common evaluation methods which improves the quality of the evaluation and reduces their computation time by 65 to 95 %, depending on the metric. our code is fully open source.
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arxiv:2309.08049
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this work deals with two types of feynman integrals in perturbative quantum field theory : the 2 - loop 2 - point kite, with 5 arbitrary internal masses, and its completion by a sixth propagator, to give a 3 - loop tetrahedral tadpole, with 6 arbitrary masses. these general - mass cases cover broken and unbroken gauge theories, based on the lie algebras u ( 1 ), su ( 2 ) and su ( 3 ), for the electromagnetic, weak and strong interactions. the elliptic substructure of these integrals should not be regarded as an obstruction. rather, it is a bonus, thanks to the arithmetic - geometric mean of gauss. compact formulae are given, to handle all cases. zero - mass limits are carefully considered. anomalous thresholds of triangles in the kite pose no problem. the number theory of tadpoles is investigated, with intriguing results.
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arxiv:2212.01962
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whole brain segmentation using deep learning ( dl ) is a very challenging task since the number of anatomical labels is very high compared to the number of available training images. to address this problem, previous dl methods proposed to use a global convolution neural network ( cnn ) or few independent cnns. in this paper, we present a novel ensemble method based on a large number of cnns processing different overlapping brain areas. inspired by parliamentary decision - making systems, we propose a framework called assemblynet, made of two " assemblies " of u - nets. such a parliamentary system is capable of dealing with complex decisions and reaching a consensus quickly. assemblynet introduces sharing of knowledge among neighboring u - nets, an " amendment " procedure made by the second assembly at higher - resolution to refine the decision taken by the first one, and a final decision obtained by majority voting. when using the same 45 training images, assemblynet outperforms global u - net by 28 % in terms of the dice metric, patch - based joint label fusion by 15 % and slant - 27 by 10 %. finally, assemblynet demonstrates high capacity to deal with limited training data to achieve whole brain segmentation in practical training and testing times.
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arxiv:1906.01862
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a droplet can deform a soft substrate due to capillary forces when they are in contact. we study the static deformation of a soft solid layer coated on a rigid cylindrical fiber when an axisymmetric barrel - shaped droplet is embracing it. we find that the elastic deformation increases with decreasing rigid fiber radius. significant disparities of deformation between the solid - liquid side and the solid - gas side are found when their solid surface tensions are different. when the coated layer is soft enough and the rigid fiber radius is less than the thickness of the coated layer, pronounced displacement oscillations are observed. such slow decay of deformation with distances from the contact line position suggests a possible long - range interaction between droplets on a soft - layer - coated fiber.
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arxiv:2307.13140
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thor is the first open - source general circulation model ( gcm ) developed from scratch to study the atmospheres and climates of exoplanets, free from earth - or solar system - centric tunings. it solves the general non - hydrostatic euler equations ( instead of the primitive equations ) on a sphere using the icosahedral grid. in the current study, we report major upgrades to thor, building upon the work of mendon \ c { c } a et al. ( 2016 ). first, while the horizontally explicit vertically implicit ( hevi ) integration scheme is the same as that described in mendon \ c { c } a et al. ( 2016 ), we provide a clearer description of the scheme and improved its implementation in the code. the differences in implementation between the hydrostatic shallow ( hss ), quasi - hydrostatic deep ( qhd ) and non - hydrostatic deep ( nhd ) treatments are fully detailed. second, standard physics modules are added : two - stream, double - gray radiative transfer and dry convective adjustment. third, thor is tested on additional benchmarks : tidally - locked earth, deep hot jupiter, acoustic wave, and gravity wave. fourth, we report that differences between the hydrostatic and non - hydrostatic simulations are negligible in the earth case, but pronounced in the hot jupiter case. finally, the effects of the so - called " sponge layer ", a form of drag implemented in most gcms to provide numerical stability, are examined. overall, these upgrades have improved the flexibility, user - friendliness, and stability of thor.
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arxiv:1911.13158
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we determine the polarization of the bulk $ ^ { 13 } $ c nuclear spin system in diamond produced by interaction with optically oriented nitrogen - vacancy ( nv - ) defect centers. $ ^ { 13 } $ c nuclei are polarized into the higher energy zeeman state with a bulk - average polarization up to 5. 2 %, although local polarization may be higher. the kinetics of polarization are temperature independent, and occur within 5 minutes. fluctuations in the dipolar field of the nv - center spin bath are identified as the mechanism by which nuclear spin transitions are induced near defect centers. polarization is then transported to the bulk material via spin diffusion, which accounts for the observed kinetics of polarization. these results indicate control over the nuclear spin bath, a methodology to study dynamics of an nv - center ensemble, and application to sensitivity - enhanced nmr.
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arxiv:0911.1098
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we give a systematic account of the exterior algebra of forms on q - minkowski space, introducing the q - exterior derivative, q - hodge star operator, q - coderivative, q - laplace - beltrami operator and the q - lie - derivative. with these tools at hand, we then give a detailed exposition of the q - d ' alembert and q - maxwell equation. for both equations we present a q - momentum - indexed family of plane wave solutions. we also discuss the gauge freedom of the q - maxwell field and give a q - spinor analysis of the q - field strength tensor.
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arxiv:hep-th/9404054
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we propose a three - stage 6 dof object detection method called dpodv2 ( dense pose object detector ) that relies on dense correspondences. we combine a 2d object detector with a dense correspondence estimation network and a multi - view pose refinement method to estimate a full 6 dof pose. unlike other deep learning methods that are typically restricted to monocular rgb images, we propose a unified deep learning network allowing different imaging modalities to be used ( rgb or depth ). moreover, we propose a novel pose refinement method, that is based on differentiable rendering. the main concept is to compare predicted and rendered correspondences in multiple views to obtain a pose which is consistent with predicted correspondences in all views. our proposed method is evaluated rigorously on different data modalities and types of training data in a controlled setup. the main conclusions is that rgb excels in correspondence estimation, while depth contributes to the pose accuracy if good 3d - 3d correspondences are available. naturally, their combination achieves the overall best performance. we perform an extensive evaluation and an ablation study to analyze and validate the results on several challenging datasets. dpodv2 achieves excellent results on all of them while still remaining fast and scalable independent of the used data modality and the type of training data
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arxiv:2207.02805
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