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we present a major revamp of the point - location data structure for general two - dimensional subdivisions via randomized incremental construction, implemented in cgal, the computational geometry algorithms library. we can now guarantee that the constructed directed acyclic graph g is of linear size and provides logarithmic query time. via the construction of the voronoi diagram for a given point set s of size n, this also enables nearest - neighbor queries in guaranteed o ( log n ) time. another major innovation is the support of general unbounded subdivisions as well as subdivisions of two - dimensional parametric surfaces such as spheres, tori, cylinders. the implementation is exact, complete, and general, i. e., it can also handle non - linear subdivisions. like the previous version, the data structure supports modifications of the subdivision, such as insertions and deletions of edges, after the initial preprocessing. a major challenge is to retain the expected o ( n log n ) preprocessing time while providing the above ( deterministic ) space and query - time guarantees. we describe an efficient preprocessing algorithm, which explicitly verifies the length l of the longest query path in o ( n log n ) time. however, instead of using l, our implementation is based on the depth d of g. although we prove that the worst case ratio of d and l is theta ( n / log n ), we conjecture, based on our experimental results, that this solution achieves expected o ( n log n ) preprocessing time. | arxiv:1205.5434 |
to understand the origin of unconventional charge - density - wave ( cdw ) states in cuprate superconductors, we establish the self - consistent cdw equation, and analyze the cdw instabilities based on the realistic hubbard model, without assuming any $ q $ - dependence and the form factor. many higher - order many - body processes, which are called the vertex corrections, are systematically generated by solving the cdw equation. when the spin fluctuations are strong, the uniform $ q = 0 $ nematic cdw with $ d $ - form factor shows the leading instability. the axial nematic cdw instability at $ q = q _ a = ( \ delta, 0 ) $ ( $ \ delta \ approx \ pi / 2 $ ) is the second strongest, and its strength increases under the static uniform cdw order. the present theory predicts that uniform cdw transition emerges at a high temperature, and it stabilize the axial $ q = q _ a $ cdw at $ t = t _ { cdw } $. it is confirmed that the higher - order aslamazov - larkin processes cause the cdw orders at both $ q = 0 $ and $ q _ a $. | arxiv:1806.01132 |
in holomorphic dynamics, complex box mappings arise as first return maps to well - chosen domains. they are a generalization of polynomial - like mapping, where the domain of the return map can have infinitely many components. they turned out to be extremely useful in tackling diverse problems. the purpose of this paper is : - to illustrate some pathologies that can occur when a complex box mapping is not induced by a globally defined map and when its domain has infinitely many components, and to give conditions to avoid these issues. - to show that once one has a box mapping for a rational map, these conditions can be assumed to hold in a very natural setting. thus we call such complex box mappings dynamically natural. - many results in holomorphic dynamics rely on an interplay between combinatorial and analytic techniques : ( * ) the enhanced nest by kozlovski - shen - van strien ; ( * ) the covering lemma by kahn - lyubich ; ( * ) the qc - criterion, the spreading principle. the purpose of this paper is to make these tools more accessible so that they can be used as a ' black box ', so one does not have to redo the proofs in new settings. - to give an intuitive, but also rather detailed, outline of the proof of the following results by kozlovski - van strien for non - renormalizable dynamically natural box mappings : ( * ) puzzle pieces shrink to points ; ( * ) topologically conjugate non - renormalizable polynomials and box mappings are quasiconformally conjugate. - we prove the fundamental ergodic properties for dynamically natural box mappings. this leads to some necessary conditions for when such a box mapping supports a measurable invariant line field on its filled julia set. these mappings are the analogues of lattes maps in this setting. - we prove a version of mane ' s theorem for complex box mappings concerning expansion along orbits of points that avoid a neighborhood of the set of critical points. | arxiv:2105.08654 |
the coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. in addition to ordinary feynman integrals, there are, at 2 - loop order, christ - lee ( cl ) terms, derived either by correctly ordering the operators in the hamiltonian, or by resolving ambiguous feynman integrals. renormalization theory depends on the subgraph structure of ordinary feynamn graphs. the cl terms do not have subgraph structure. we show how to carry out enormalization in the presene of cl terms, by re - expressing these as ` pseudo - feynman ' inegrals. we also explain how energy divergences cancel. | arxiv:1204.1722 |
in the paper, it is proved that any $ c ^ { 1 } $ - function on gl ( n ) which is locally $ p $ - invariant ( here $ p $ is the affine ( sub ) group of gl ( n ) ) is locally $ g $ - invairant. there is also a statement for distributions ( a very weak form of baruch ' s results ). | arxiv:0707.0779 |
we propose a simple method to spectrally resolve single - spins in a cold atomic system, thus realizing single - spin addressing. this scheme uses a dressing field with a spatially - dependent coupling to the atoms. we realize this scheme experimentally using a linear chain of trapped ions that are separated by $ \ sim3 $ $ \ mu $ m, dressed by a laser field that is resonant with the micromotion sideband of a narrow optical transition. | arxiv:1210.7336 |
abridged : ngc5253 was previously studied by our group with the aim to elucidate in detail the starburst interaction processes. some open issues regarding the 2d structure of the main properties of the ionized gas remain to be addressed. using ifs data obtained with flames, we derived 2d maps for different tracers of electron density ( n _ e ), electron temperature ( t _ e ) and ionization degree. the maps for n _ e as traced by several line ratios are compatible with a 3d stratified view of the nebula with the highest n _ e in the innermost layers and a decrease of n _ e outwards. to our knowledge, this is the first time that a t _ e map based on [ sii ] lines for an extragalactic object is presented. the joint interpretation of our two t _ e maps is consistent with a t _ e structure in 3d with higher temperatures close to the main ionizing source surrounded by a colder and more diffuse component. the highest ionization degree is found at the peak of emission for the gas with relatively high ionization in the main ghiir and lower ionization degree delineating the more extended diffuse component. abundances for o, ne and ar are constant over the mapped area within < 0. 1 dex. the mean 12 + log ( o / h ) is 8. 26 while the relative abundances of log ( n / o ), log ( ne / o ) and log ( ar / o ) were \ sim - 1. 32, - 0. 65 and - 2. 33, respectively. there are two locations with enhanced n / o. the first ( log ( n / o ) \ sim - 0. 95 ) is associated to two super star clusters. the second ( log ( n / o ) \ sim - 1. 17 ), reported here for the first time, is associated to two moderately massive ( 2 - 4x10 ^ 4 m _ sun ) and relatively old ( \ sim10 myr ) clusters. a comparison of the n / o map with those produced by strong line methods supports the use of n2o2 over n2s2 in the search for chemical inhomogeneities within a galaxy. the results on the localized nitrogen enhancement were used to compile and discuss the factors that affect the complex relationship between wolf - rayet stars and n / o excess. | arxiv:1206.2275 |
in this paper, we study non - interacting bosons in a disordered one - dimensional optical lattice in a harmonic potential. we consider the case of deterministic disorder produced by an aubry - andr \ ' { e } potential. using exact diagonalization, we investigate both the zero temperature and the finite temperature properties. we investigate the localization properties by using an entanglement measure. we find that the extreme sensitivity of the localization properties to the number of lattice sites in finite size closed chains disappear in open chains. this feature continues to be present in the presence of a harmonic confining potential. the disorder is found to strongly reduce the bose - einstein condensation temperature and the condensate fraction in open chains. the low temperature thermal depletion rate of the condensate fraction increases considerably with increasing disorder strength. we also find that the critical disorder strength required for localization increases with increasing strength of the harmonic potential. further, we find that the low temperature condensate fraction undergoes a sharp drop to 0. 5 in the localization transition region. the temperature dependence of the specific heat is found to be only marginally affected by the disorder. | arxiv:1212.3073 |
we present calculations for the shear viscosity of the hot and dense quark - gluon plasma ( qgp ) using the partonic scattering cross sections as a function of temperature $ t $ and baryon chemical potential $ \ mu _ b $ from the dynamical quasiparticle model ( dqpm ) that is matched to reproduce the equation of state of the partonic system above the deconfinement temperature $ t _ c $ from lattice qcd. to this aim we calculate the collisional widths for the partonic degrees of freedom at finite $ t $ and $ \ mu _ b $ in the time - like sector and conclude that the quasiparticle limit holds sufficiently well. furthermore, the ratio of shear viscosity $ \ eta $ over entropy density $ s $, i. e. $ \ eta / s $, is evaluated using these collisional widths and are compared to lqcd calculations for $ \ mu _ b $ = 0 as well. we find that the ratio $ \ eta / s $ is in agreement with the results of calculations within the original dqpm on the basis of the kubo formalism. furthermore, there is only a very modest change of $ \ eta / s $ with the baryon chemical $ \ mu _ b $ as a function of the scaled temperature $ t / t _ c ( \ mu _ b ) $. | arxiv:1911.03131 |
we extend a recent billiard model of the nuclear n - body hamiltonian to consider a finite two - body interaction. this permits a treatment of the hamiltonian by a mean field theory, and also allows the possibility to model reactions between nuclei. the density and the mean field potential can be accurately described by a scaling function which shows the qualitative features of the liquid drop picture of the nucleus. | arxiv:nucl-th/9906054 |
we briefly describe the current version of the phoenix code. we then present some illustrative results from the modeling of type ia and type ii supernovae, hot stars, and irradiated giant planets. good fits to observations can be obtained, when account is taken for spherically symmetric, line - blanketed, static or expanding atmospheres. | arxiv:astro-ph/0209052 |
this paper proposes block - level precoder ( blp ) designs for a multi - input single - output ( miso ) system that performs joint sensing and communication across multiple cells and users. the cramer - rao - bound for estimating a target ' s azimuth angle is determined for coordinated beamforming ( cbf ) and coordinated multi - point ( comp ) scenarios while considering inter - cell communication and sensing links. the formulated optimization problems to minimize the crb and maximize the minimum - signal - to - interference - plus - noise - ratio ( sinr ) are non - convex and are represented in the semidefinite relaxed ( sdr ) form to solve using an alternate optimization algorithm. the proposed solutions show improved performance compared to the baseline scenario that neglects the signal component from neighboring cells. | arxiv:2402.18405 |
this talk gives a brief discussion of the motivations and principles behind computer automated expert semi - analytical resummation ( caesar ) for qcd final states. | arxiv:hep-ph/0407367 |
tactile sensing is crucial for robots aiming to achieve human - level dexterity. among tactile - dependent skills, tactile - based object tracking serves as the cornerstone for many tasks, including manipulation, in - hand manipulation, and 3d reconstruction. in this work, we introduce normalflow, a fast, robust, and real - time tactile - based 6dof tracking algorithm. leveraging the precise surface normal estimation of vision - based tactile sensors, normalflow determines object movements by minimizing discrepancies between the tactile - derived surface normals. our results show that normalflow consistently outperforms competitive baselines and can track low - texture objects like table surfaces. for long - horizon tracking, we demonstrate when rolling the sensor around a bead for 360 degrees, normalflow maintains a rotational tracking error of 2. 5 degrees. additionally, we present state - of - the - art tactile - based 3d reconstruction results, showcasing the high accuracy of normalflow. we believe normalflow unlocks new possibilities for high - precision perception and manipulation tasks that involve interacting with objects using hands. the video demo, code, and dataset are available on our website : https : / / joehjhuang. github. io / normalflow. | arxiv:2412.09617 |
we study stationary and dynamical properties of the many - body landau - zener dynamics of a bose quantum fluid confined in two coupled one - dimensional chains, using a many - body generalization recently reported [ y. - a. chen et al. ], within the decoupling approximation and the one - level band scheme. the energy spectrum evidences the structure of the avoided level crossings as a function of the on - site inter particle interaction strength. on the dynamical side, a phase diagram of the transfer efficiency across ground - state and inverse sweeps is presented. a totally different scenario with respect to the original single - particle landau - zener scheme is found for ground - state sweeps, in which a breakdown of the adiabatic region emerges as the sweep rate decreases. on the contrary, the transfer efficiency across inverse sweeps reveals consistent results with the single - particle landau - zener predictions. in the strong coupling regime, we find that there is a critical value of the on - site interaction for which the transfer of particles starts to vanish independently of the sweep rate. our results are in qualitative agreement with those of the experimental counterpart. | arxiv:1106.6179 |
we present a stabilized microwave - frequency transfer technique that is based on optical phase - sensing and optical phase - actuation. this technique shares several attributes with optical - frequency transfer and therefore exhibits several advantages over other microwave - frequency transfer techniques. we demonstrated stabilized transfer of an 8, 000 mhz microwave - frequency signal over a 166 km metropolitan optical fiber network, achieving a fractional frequency stability of 6. 8x10 ^ - 14 hz / hz at 1 s integration, and 5. 0x10 ^ - 16 hz / hz at 1. 6x10 ^ 4 s. this technique is being considered for use on the square kilometre array ska1 - mid radio telescope. | arxiv:1705.01169 |
rain removal has recently attracted increasing research attention, as it is able to enhance the visibility of rain videos. however, the existing learning based rain removal approaches for videos suffer from insufficient training data, especially when applying deep learning to remove rain. in this paper, we establish a large - scale video database for rain removal ( lasvr ), which consists of 316 rain videos. then, we observe from our database that there exist the temporal correlation of clean content and similar patterns of rain across video frames. according to these two observations, we propose a two - stream convolutional long - and short - term memory ( convlstm ) approach for rain removal in videos. the first stream is composed of the subnet for rain detection, while the second stream is the subnet of rain removal that leverages the features from the rain detection subnet. finally, the experimental results on both synthetic and real rain videos show the proposed approach performs better than other state - of - the - art approaches. | arxiv:1906.02526 |
identifying mix - and - match relationships between fashion items is an urgent task in a fashion e - commerce recommender system. it will significantly enhance user experience and satisfaction. however, due to the challenges of inferring the rich yet complicated set of compatibility patterns in a large e - commerce corpus of fashion items, this task is still underexplored. inspired by the recent advances in multi - relational knowledge representation learning and deep neural networks, this paper proposes a novel translation - based neural fashion compatibility modeling ( transnfcm ) framework, which jointly optimizes fashion item embeddings and category - specific complementary relations in a unified space via an end - to - end learning manner. transnfcm places items in a unified embedding space where a category - specific relation ( category - comp - category ) is modeled as a vector translation operating on the embeddings of compatible items from the corresponding categories. by this way, we not only capture the specific notion of compatibility conditioned on a specific pair of complementary categories, but also preserve the global notion of compatibility. we also design a deep fashion item encoder which exploits the complementary characteristic of visual and textual features to represent the fashion products. to the best of our knowledge, this is the first work that uses category - specific complementary relations to model the category - aware compatibility between items in a translation - based embedding space. extensive experiments demonstrate the effectiveness of transnfcm over the state - of - the - arts on two real - world datasets. | arxiv:1812.10021 |
if gamma - ray bursters are at cosmological distances - as suggested by their isotropic distribution on the sky and by their number - intensity relation - then the burst profiles will be stretched in time, by an amount proportional to the redshift, 1 + $ z $. we have tested data from the { \ it compton } gamma ray observatory ' s burst and transient source experiment ( batse ) for such time dilation. our measures of time scale are constructed to avoid selection effects arising from intensity differences by rescale all bursts to fiducial levels of peak intensity and noise bias. the three tests involved total count rate above background, wavelet decomposition, and alignment of the highest peaks. in all three tests, the dim bursts are stretched by a factor of about two relative to the bright ones, over seven octaves of time scale. we calibrated the measurements by dilating synthetic bursts that approximate the temporal characteristics of bright batse bursts. results are consistent with bursts of batse ' s peak - flux completeness limit being at cosmological distances corresponding to $ z \ sim 1 $, and thus with independent cosmological interpretations of the batse number - intensity relation. | arxiv:astro-ph/9312049 |
we study the jahn - teller effect of positive fullerene ions $ ^ 2 $ c $ _ { 60 } ^ { + } $ and $ ^ 1 $ c $ _ { 60 } ^ { 2 + } $. the aim is to discover if this case, in analogy with the negative ion, possesses a berry phase or not, and what are the consequences on dynamical jahn - teller quantization. working in the linear and spherical approximation, we find no berry phase in $ ^ 1 $ c $ _ { 60 } ^ { 2 + } $, and presence / absence of berry phase for coupling of one $ l = 2 $ hole to an $ l = 4 $ / $ l = 2 $ vibration. we study in particular the special equal - coupling case ( $ g _ 2 = g _ 4 $ ), which is reduced to the motion of a particle on a 5 - dimensional sphere. in the icosahedral molecule, the final outcome assesses the presence / absence of a berry phase of $ \ pi $ for the $ h _ u $ hole coupled to $ g _ g $ / $ h _ h $ vibrations. some qualitative consequences on ground - state symmetry, low - lying excitations, and electron emission from c $ _ { 60 } $ are spelled out. | arxiv:cond-mat/9509114 |
rigorous results on the nonlinear dynamics of a dilute bose gas with a negative scattering length in an harmonic magnetic trap are presented and sufficient conditions for the collapse of the system are formulated. by using the virial theorem for the gross - pitaevskii equations in an external field we analyze the temporal evolution of the mean square radius of the gas cloud. in the 2d case the quantity undergoes harmonic oscillation with frequency $ 2 \ omega _ 0 $ it implies that for a negative value of energy of the system, the gas cloud will collapse after a finite time interval. for positive energy the cloud collapses if the initial conditions correspond to a large enough amplitude of oscillations. stable oscillations with a small amplitude are possible. in the 3d case the system also collapsed after a finite time for a state with negative energy. a stringent condition for the collapse is also derived. | arxiv:cond-mat/9605119 |
at the precision reached in current lattice qcd calculations, electromagnetic effects are becoming numerically relevant. we will present preliminary results for electromagnetic corrections to light hadron masses, based on simulations in which a $ \ mathrm { u } ( 1 ) $ degree of freedom is superimposed on $ n _ f = 2 + 1 $ qcd configurations from the bmw collaboration. | arxiv:1011.4189 |
we extend an effective theory framework developped in refs. [ 1, 2 ] to sum electroweak sudakov logarithms in high energy processes to also include massive gauge bosons in the final state. the calculations require an additional regulator on top of dimensional regularization to tame the collinear singularities. we propose to use the delta regulator, which respects soft - collinear factorization. | arxiv:0905.1141 |
the atlas high level trigger ( hlt ) system provides software - based event selection after the initial lvl1 hardware trigger. it is composed of two stages, the lvl2 trigger and the event filter. the hlt is implemented as software tasks running on large processor farms. an essential part of the hlt is the supervision system, which is responsible for configuring, coordinating, controlling and monitoring the many hundreds of processes running in the hlt. a prototype implementation of the supervision system, using tools from the atlas online software system is presented. results from scalability tests are also presented where the supervision system was shown to be capable of controlling over 1000 hlt processes running on 230 nodes. | arxiv:hep-ex/0305093 |
protein - protein interactions ( protein functionalities ) are mediated by water, which compacts individual proteins and promotes close and temporarily stable large - area protein - protein interfaces. in their classic paper kyte and doolittle ( kd ) concluded that the " simplicity and graphic nature of hydrophobicity scales make them very useful tools for the evaluation of protein structures ". in practice, however, attempts to develop hydrophobicity scales ( for example, compatible with classical force fields ( cff ) in calculating the energetics of protein folding ) have encountered many difficulties. here we suggest an entirely different approach, based on the idea that proteins are self - organized networks, subject to finite - scale criticality ( like some network glasses ). we test this proposal against two small proteins that are delicately balanced between alpha and alpha / beta structures, with different functions encoded with only 12 % of their amino acids. this example explains why protein structure prediction is so challenging, and it provides a severe test for the accuracy and content of hydrophobicity scales. the new method confirms kd ' s evaluation, and at the same time suggests that protein structure, dynamics and function can be best discussed without using cff. | arxiv:0803.2644 |
: british mathematician active in the theory of finite groups, knot theory, number theory, combinatorial game theory and coding theory. he is best known for the invention of the cellular automaton called conway ' s game of life. sir john cornforth frs, faa ( 1917 – 2013 ) : australian – british chemist who won the nobel prize in chemistry in 1975 for his work on the stereochemistry of enzyme - catalysed reactions. jan baudouin de courtenay ( 1845 – 1929 ) : polish linguist and slavist, best known for his theory of the phoneme and phonetic alternations. jerry coyne ( 1949 – ) : american evolutionary biologist and professor, known for his books on evolution and commentary on the intelligent design debate. francis crick ( 1916 – 2004 ) : english molecular biologist, physicist, and neuroscientist ; noted for being one of the co - discoverers of the structure of the dna molecule in 1953. he was awarded the nobel prize in physiology or medicine in 1962. george washington crile ( 1864 – 1943 ) : american surgeon. crile is now formally recognized as the first surgeon to have succeeded in a direct blood transfusion. pierre curie ( 1859 – 1906 ) : french physicist, a pioneer in crystallography, magnetism, piezoelectricity and radioactivity, and nobel laureate. in 1903 he received the nobel prize in physics with his wife, marie curie, and henri becquerel, " in recognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by professor henri becquerel ". = = d = = sir howard dalton frs ( 1944 – 2008 ) : british microbiologist, chief scientific advisor to the uk ' s department for environment, food and rural affairs from march 2002 to september 2007. richard dawkins ( 1941 – ) : english evolutionary biologist, creator of the concept of the meme ; outspoken atheist and populariser of science, author of the god delusion and founder of the richard dawkins foundation for reason and science. christian de duve ( 1917 – 2013 ) : belgian cytologist and biochemist. he made serendipitous discoveries of two cell organelles, the peroxisome and lysosome, for which he shared the 1974 nobel prize in physiology or medicine with albert claude and george e. palade ( " for their discoveries concerning the structural and functional organization of the cell " ). in addition to discovering and naming the peroxiso | https://en.wikipedia.org/wiki/List_of_atheists_in_science_and_technology |
an essential stage in computer aided diagnosis of chest x rays is automated lung segmentation. due to rib cages and the unique modalities of each persons lungs, it is essential to construct an effective automated lung segmentation model. this paper presents a reliable model for the segmentation of lungs in chest radiographs. our model overcomes the challenges by learning to ignore unimportant areas in the source chest radiograph and emphasize important features for lung segmentation. we evaluate our model on public datasets, montgomery and shenzhen. the proposed model has a dice coefficient of 98. 1 percent which demonstrates the reliability of our model. | arxiv:2210.10545 |
we calculate the wilson coefficients of all dimension 6 gluon operators with non zero spin in the correlation function between two heavy vector currents. for the twist - 4 part, we first identify the three independent gluon operators, and then proceed with the calculation of the wilson coefficients using the fixed point gauge. together with the previous calculation of the wilson coefficients for the dimension 6 scalar gluon operators by nikolaev and radyushkin, our result completes the list of all the wilson coefficients of dimension 6 gluon operators in the correlation function between heavy vector currents. we apply our results to investigate the mass of $ j / \ psi $ in nuclear matter using qcd sum rules. using an upper bound estimate on the matrix elements of the dimension 6 gluon operators to linear order in density, we find that the density dependent contribution from dimension 6 operators is less than 40 % of the dimension 4 operators with opposite sign. the final result gives about - 4 mev mass shift for the charmonium at rest in nuclear matter. | arxiv:nucl-th/0002002 |
we propose a novel framework and a solution to tackle the continual learning ( cl ) problem with changing network architectures. most cl methods focus on adapting a single architecture to a new task / class by modifying its weights. however, with rapid progress in architecture design, the problem of adapting existing solutions to novel architectures becomes relevant. to address this limitation, we propose heterogeneous continual learning ( hcl ), where a wide range of evolving network architectures emerge continually together with novel data / tasks. as a solution, we build on top of the distillation family of techniques and modify it to a new setting where a weaker model takes the role of a teacher ; meanwhile, a new stronger architecture acts as a student. furthermore, we consider a setup of limited access to previous data and propose quick deep inversion ( qdi ) to recover prior task visual features to support knowledge transfer. qdi significantly reduces computational costs compared to previous solutions and improves overall performance. in summary, we propose a new setup for cl with a modified knowledge distillation paradigm and design a quick data inversion method to enhance distillation. our evaluation of various benchmarks shows a significant improvement on accuracy in comparison to state - of - the - art methods over various networks architectures. | arxiv:2306.08593 |
in his ph. d. thesis, c. lehr offers an algorithm which gives the stable model for p - cyclic covers of the projective line over a p - adic field under the conditions that the branch locus whose cardinal is m + 1 has the so called equidistant geometry and m < p. in this note we give an algorithm also in the equidistant geometry case but without condition on m. in particular we are able to study the reduction at 2 of hyperelliptic curves with equidistant branch locus. | arxiv:math/0112042 |
a dynamical scalar field represents the simplest generalization of a pure cosmological constant as a candidate to explain the recent evidence in favour of the accelerated cosmic expansion. we review the dynamical properties of such a component, and argue that, even if the background expectation value of this field is fixed and the equation of state is the same as a cosmological constant, scalar field fluctuations can still be used to distinguish the two components. we compare predicted spectra of cosmic microvave background ( cmb ) anisotropies in tracking scalar field cosmologies with the present cmb data, in order to get constraints on the amount and equation of state of dark energy. high precision experiments like snap, { \ sc planck } and { \ sc snfactory }, together with the data on large scale structure, are needed to probe this issue with the necessary accuracy. here we show the intriguing result that, with a strong prior on the value of the hubble constant today, the assumption of a flat universe, and consistency relations between amplitude and spectral index of primordial gravitational waves, the present cmb data at $ 1 \ sigma $ give indication of a dark energy equation of state larger than - 1, while the ordinary cosmological constant is recovered at $ 2 \ sigma $. | arxiv:astro-ph/0205217 |
we perform a detailed phenomenological analysis of how well hadronization in nuclear environments can be described in terms of effective fragmentation functions. the medium modified fragmentation functions are assumed to factorize from the partonic scattering cross sections and evolve in the hard scale in the same way as the standard or vacuum fragmentation functions. based on precise data on semi - inclusive deep - inelastic scattering off nuclei and hadron production in deuteron - gold collisions, we extract sets of effective fragmentation functions for pions and kaons at nlo accuracy. the obtained sets provide a rather accurate description of the kinematical dependence of the analyzed cross sections and are found to differ significantly from standard fragmentation functions both in shape and magnitude. our results support the notion of factorization and universality in the studied nuclear environments, at least in an effective way and within the precision of the available data. | arxiv:0912.1311 |
the turbulent transport of minority species / impurities is investigated in 2d drift - wave turbulence as well as in 3d toroidal drift - alfven edge turbulence. the full effects of perpendicular and - - in 3d - - parallel advection are kept for the impurity species. anomalous pinch effects are recovered and explained in terms of turbulent equipartition ( tep ) | arxiv:physics/0410092 |
we compare the systematics of the magnetic field geometry in the " red " low - energy peaked bl lacs ( lbls ) and " blue " high - energy peaked bl lacs ( hbls ) using vlbi polarimetric images. the lbls are primarily " radio - - selected " bl lacs and the hbls are primarily " x - ray selected ". in contrast to the lbls, which show predominantly transverse jet magnetic fields, the hbls show predominantly longitudinal fields. thus, while the sed peaks of core - dominated quasars, lbls and hbls form a sequence of increasing frequency, the magnetic field geometry does not follow an analogous sequence. we briefly investigate possible connections between the observed parsec - scale magnetic field structures and circular polarization measurements in the literature on various spatial scales. | arxiv:astro-ph/0301068 |
we study dynamical gravitational collapse in a theory with an infinite tower of higher - derivative corrections to the einstein - hilbert action and we show that, under very general conditions, it leads to the formation of regular black holes. our results are facilitated by the use of a class of theories that possess second - order equations on spherically symmetric metrics, but which are general enough to provide a basis for the gravitational effective action. we analytically solve the collapse of a thin shell of dust and show that it inevitably experiences a bounce at small radius and that its motion can be extended to arbitrary proper time. the collapse of the shell always gives rise to a singularity - free, geodesically complete spacetime that contains horizons if the total mass is above a critical value. in that case, the shell bounces into a new universe through a white hole explosion. our construction provides, to the best of our knowlege, the first fully dynamical description of formation of regular black holes, and it suggests that higher - derivative corrections may be the most natural way to resolve the singularities of einstein ' s theory. | arxiv:2412.02742 |
octet hyperon charge radii are calculated in a chiral constituent quark model including electromagnetic exchange currents between quarks. in impulse approximation one observes a decrease of the hyperon charge radii with increasing strangeness. this effect is reduced by exchange currents. due to exchange currents, the charge radius of the negatively charged hyperons are close to the proton charge radius. | arxiv:nucl-th/9809015 |
leddar pixset is a new publicly available dataset ( dataset. leddartech. com ) for autonomous driving research and development. one key novelty of this dataset is the presence of full - waveform data from the leddar pixell sensor, a solid - state flash lidar. full - waveform data has been shown to improve the performance of perception algorithms in airborne applications but is yet to be demonstrated for terrestrial applications such as autonomous driving. the pixset dataset contains approximately 29k frames from 97 sequences recorded in high - density urban areas, using a set of various sensors ( cameras, lidars, radar, imu, etc. ) each frame has been manually annotated with 3d bounding boxes. | arxiv:2102.12010 |
we employ a variety of ab initio methods including faddeev - yakubovsky equations, no - core configuration interaction approach, coupled - cluster theory and in - medium similarity renormalization group to perform a comprehensive analysis of the nucleon - deuteron elastic and breakup reactions and selected properties of light and medium - mass nuclei up to 48ca using the recently constructed semilocal coordinate - space regularized chiral nucleon - nucleon potentials. we compare the results with those based on selected phenomenological and chiral eft two - nucleon potentials, discuss the convergence pattern of the chiral expansion and estimate the achievable theoretical accuracy at various chiral orders using the novel approach to quantify truncation errors of the chiral expansion without relying on cutoff variation. we also address the robustness of this method and explore alternative ways to estimate the theoretical uncertainty from the truncation of the chiral expansion. | arxiv:1802.08584 |
nitrogen - bearing molecules display variable isotopic fractionation levels in different astronomical environments such as in the interstellar medium or in the solar system. models of interstellar chemistry are unable to induce nitrogen fraction in cold molecular clouds as exchange reactions for 15n are mostly inefficient. here, we developed a new gas - grain model for nitrogen fractionation including a thorough search for new nitrogen fractionation reactions and a realistic description of atom depletion onto interstellar dust particles. we show that, while dense molecular cloud gas - phase chemistry alone leads to very low fractionation, 14n atoms are preferentially depleted from the gas - phase due to a mass dependent grain surface sticking rate for atomic nitrogen. however, assuming an elementary 14n / 15n ratio of 441 ( equal to the solar wind value ), our model leads to only low 15n enrichment for all n - containing species synthesized in the gas - phase with predicted 14n / 15n ratios in the range 360 - 400. higher enrichment levels can neither be explained by this mechanism, nor through chemistry, with two possible explanations. ( i ) the elementary 14n / 15n ratio in the local ism is smaller, as suggested by the recent work of romano et al, with an hypothetic 15nnh + and 15nnh + depletion due to variation of the electronic recombination rate constant variation with the isotopes. ( ii ) n2 photodissociation leads to variable nitrogen fractionation in diffuse molecular clouds where photons play an important role, which is conserved during dense molecular cloud formation as suggested by the work of furuya & aikawa. | arxiv:2012.07713 |
while increasingly complex approaches to question answering ( qa ) have been proposed, the true gain of these systems, particularly with respect to their expensive training requirements, can be inflated when they are not compared to adequate baselines. here we propose an unsupervised, simple, and fast alignment and information retrieval baseline that incorporates two novel contributions : a \ textit { one - to - many alignment } between query and document terms and \ textit { negative alignment } as a proxy for discriminative information. our approach not only outperforms all conventional baselines as well as many supervised recurrent neural networks, but also approaches the state of the art for supervised systems on three qa datasets. with only three hyperparameters, we achieve 47 \ % p @ 1 on an 8th grade science qa dataset, 32. 9 \ % p @ 1 on a yahoo! answers qa dataset and 64 \ % map on wikiqa. we also achieve 26. 56 \ % and 58. 36 \ % on arc challenge and easy dataset respectively. in addition to including the additional arc results in this version of the paper, for the arc easy set only we also experimented with one additional parameter - - number of justifications retrieved. | arxiv:1807.01836 |
ssp distribution is an important parameter for underwater positioning, navigation and timing ( pnt ) because it affects the propagation mode of underwater acoustic signals. to accurate predict future sound speed distribution, we propose a hierarchical long short - - term memory ( h - - lstm ) neural network for future sound speed prediction, which explore the distribution pattern of sound velocity in the time dimension. to verify the feasibility and effectiveness, we conducted both simulations and real experiments. the ocean experiment was held in the south china sea in april, 2023. results show that the accuracy of the proposed method outperforms the state - - of - - the - - art methods. | arxiv:2310.09522 |
we investigate three different axial - vector form factors of the nucleon, $ g _ a ^ { 0 } $, $ g _ a ^ 3 $, $ g _ a ^ 8 $, within the framework of the su ( 3 ) chiral quark - soliton model, emphasizing their strangeness content. we take into account the rotational $ 1 / n _ c $ and linear strange quark ( $ m _ s $ ) contributions using the symmetry - conserving su ( 3 ) quantization and assuming isospin symmetry. the strange axial - vector form factor is also obtained and they all are discussed in the context of the parity - violating scattering of polarized electrons off the nucleon and its relevance to the strange vector form factors. | arxiv:hep-ph/0509281 |
compact wearable mapping system ( wms ) has gained significant attention due to their convenience in various applications. specifically, it provides an efficient way to collect prior maps for 3d structure inspection and robot - based " last - mile delivery " in complex environments. however, vibrations in human motion and the uneven distribution of point cloud features in complex environments often lead to rapid drift, which is a prevalent issue when applying existing lidar inertial odometry ( lio ) methods on low - cost wms. to address these limitations, we propose a novel lio for wmss based on hybrid continuous time optimization ( hcto ) considering the optimality of lidar correspondences. first, hcto recognizes patterns in human motion ( high - frequency part, low - frequency part, and constant velocity part ) by analyzing raw imu measurements. second, hcto constructs hybrid imu factors according to different motion states, which enables robust and accurate estimation against vibration - induced noise in the imu measurements. third, the best point correspondences are selected using optimal design to achieve real - time performance and better odometry accuracy. we conduct experiments on head - mounted wms datasets to evaluate the performance of our system, demonstrating significant advantages over state - of - the - art methods. video recordings of experiments can be found on the project page of hcto : \ href { https : / / github. com / kafeiyin00 / hcto } { https : / / github. com / kafeiyin00 / hcto }. | arxiv:2403.14173 |
meson decays offer a good opportunity to probe new physics. the rare kaon decay $ k ^ + \ rightarrow \ pi ^ + \ nu \ bar { \ nu } $ is one of the cleanest of them and, for this reason, is rather sensitive to new physics, in particular, vector mediators. na62 collaboration, running a fixed - target experiment at cern, recently reported an unprecedented sensitivity to this decay, namely a branching fraction of $ br ( k ^ + \ rightarrow \ pi ^ + \ nu \ bar { \ nu } ) = ( 11 ^ { + 4. 0 } _ { - 3. 5 } ) \ times 10 ^ { - 11 } $ at 68 \ % c. l. vector mediators that couple to neutrinos may yield a sizeable contribution to this decay. motivated by the new measurement, we interpret this result in the context of a concrete $ z ^ \ prime $ model, and put our findings into perspective with the correlated $ k _ l \ rightarrow \ pi ^ 0 \ nu \ bar { \ nu } $ decay measured by koto collaboration, current, and future colliders, namely the high - luminosity and high - energy lhc. | arxiv:2102.06262 |
we describe the data processing of the survey on extragalactic magnetism with sofia ( salsa legacy program ). this first data release presents 33 % ( 51. 34h out of 155. 7h, including overheads ) of the total awarded time taken from january 2020 to december 2021. our observations were performed using the newly implemented on - the - fly mapping ( otfmap ) technique in the polarimetric mode. we present the pipeline steps to obtain homogeneously reduced high - level data products of polarimetric maps of galaxies for use in scientific analysis. our approach has a general design and can be applied to sources smaller than the field - of - view of the hawc + array in any given band. we estimate that the otfmap polarimetric mode offers a reduction of observing overheads by a factor 2. 34, and an improvement in sensitivity by a factor 1. 80 when compared to previously obtained polarimetric observations using the chopping and nodding mode. the otfmap is a significant optimization of the polarimetric mode of hawc + as it ultimately reduces the cost of operations of sofia / hawc + by increasing the science collected per hour of observation up to an overall factor of 2. 49. the otfmap polarimetric mode is the standard observing strategy of salsa. the results and quantitative analysis of this first data release are presented in papers iv and v of the series. | arxiv:2204.13611 |
lumber and wood - based products are versatile construction materials that are susceptible to weakening as a result of applied stresses. to assess the effects of load duration and rate, experiments have been carried out by applying preset load profiles to sample specimens. this paper studies these effects via a damage modeling approach, by considering three models in the literature : the gerhards and foschi accumulated damage models, and a degradation model based on the gamma process. we present a statistical framework for fitting these models to failure time data generated by a combination of ramp and constant load settings, and show how estimation uncertainty can be quantified. the models and methods are illustrated and compared via a novel analysis of a hemlock lumber dataset. practical usage of the fitted damage models is demonstrated with an application to long - term reliability prediction under stochastic future loadings. | arxiv:2002.03537 |
a non linear ito equation in a hilbert space is studied by means of girsanov theorem. we consider a non linearity of polynomial growth in suitable norms, including that of quadratic type which appears in the kuramoto - sivashinsky equation and in the navier - stokes equation. we prove that girsanov theorem holds for the 1 - dimensional stochastic kuramoto - sivashinsky equation and for a modification of the 2 - and 3 - dimensional stochastic navier - stokes equation. in this way, we prove existence and uniqueness of solutions for these stochastic equations. moreover, the asymptotic behaviour for large time is characterized. | arxiv:0801.0496 |
in addition to goldstone phonons that generically emerge in the low - frequency vibrational spectrum of any solid, crystalline or glassy, structural glasses also feature other low - frequency vibrational modes. the nature and statistical properties of these modes - - often termed ` excess modes ' - - have been the subject of decades - long investigation. studying them, even using well - controlled computer glasses, has proven challenging due to strong spatial hybridization effects between phononic and nonphononic excitations, which hinder quantitative analyses of the nonphononic contribution $ { \ cal d } _ { \ rm g } ( \ omega ) $ to the total spectrum $ { \ cal d } ( \ omega ) $, per frequency $ \ omega $. here, using recent advances indicating that $ { \ cal d } _ { \ rm g } ( \ omega ) \! = \! { \ cal d } ( \ omega ) - { \ cal d } _ { \ rm d } ( \ omega ) $, where $ { \ cal d } _ { \ rm d } ( \ omega ) $ is debye ' s spectrum of phonons, we present a simple and straightforward scheme to enumerate nonphononic modes in computer glasses. our analysis establishes that nonphononic modes in computer glasses indeed make an additive contribution to the total spectrum, including in the presence of strong hybridizations. moreover, it cleanly reveals the universal $ { \ cal d } _ { \ rm g } ( \ omega ) \! \ sim \! \ omega ^ 4 $ tail of the nonphononic spectrum, and opens the way for related analyses of experimental spectra of glasses. | arxiv:2404.12735 |
we have investigated electronic structures and magnetic properties of potential zno based diluted magnetic semiconductors : ( fe, co ) and ( fe, cu ) codoped zno. the origins of ferromagnetism are shown to be different between two. ( fe, co ) codoped zno does not have a tendency of fe - o - co ferromagnetic cluster formation, and so the double exchange mechanism will not be effective. in contrast, ( fe, cu ) codoped zno has a tendency of the fe - o - cu ferromagnetic cluster formation with the charge transfer between fe and cu, which would lead to the ferromagnetism through the double - exchange mechanism. the ferromagnetic and nearly half - metallic ground state is obtained for ( fe, cu ) codoped zno. | arxiv:cond-mat/0307359 |
we have numerically investigated close scattering processes of two black holes ( bhs ). our careful analysis shows for the first time a non - merging ringdown gravitational wave coming from dynamical tidal deformations of individual bhs during their close encounter. the ringdown wave frequencies turn out to agree well with the quasi - normal ones of a single bh in perturbation theory, despite its distinctive physical context from the merging case. our study shows a new type of gravitational waveform and opens up a new exploration of strong gravitational interactions using bh encounters. | arxiv:2310.18686 |
a prescription for constructing dictionaries for cardinal spline spaces on a compact interval is provided. it is proved that such spaces can be spanned by dictionaries which are built by translating a prototype b - spline function of fixed support into the knots of the required cardinal spline space. this implies that cardinal spline spaces on a compact interval can be spanned by dictionaries of cardinal b - spline functions of broader support that the corresponding basis function. | arxiv:math/0501403 |
methanol masers can provide valuable insight into the processes involved in high - mass star formation, however the local environment in which they form is still unclear. four primary, yet conflicting, models have emerged to explain the commonly observed methanol maser structures at 6. 67 ghz. these suggest that masers trace accretion disks, outflows, shock fronts or disks dominated by infall / outflows. one proposed means of testing these models is through mapping the local magnetic field structures around maser sources, which were predicted to lie parallel to shock and outflows and perpendicular to accretion disks. to follow up this suggestion we have determined magnetic field directions from full polarisation observations of 10 6. 67 - ghz sources. we find morphology that is parallel to the source structure, indicative of shocks or outflows, in five sources and perpendicular morphology indicative of disks in three. these results do not support any of the expected models and the diverse morphologies observed indicate that the masers could be emitting from different evolutionary stages or environments, or from a common local environment with complex associated magnetic fields. to resolve this conflict we suggest a new approach that will search the simulations of massive star formation, which are just becoming available, for suitable sites for maser emission. | arxiv:1201.1687 |
we present a physics - informed gaussian process regression ( gpr ) model to predict the phase angle, angular speed, and wind mechanical power from a limited number of measurements. in the traditional data - driven gpr method, the form of the gaussian process covariance matrix is assumed and its parameters are found from measurements. in the physics - informed gpr, we treat unknown variables ( including wind speed and mechanical power ) as a random process and compute the covariance matrix from the resulting stochastic power grid equations. we demonstrate that the physics - informed gpr method is significantly more accurate than the standard data - driven one for immediate forecasting of generators ' angular velocity and phase angle. we also show that the physics - informed gpr provides accurate predictions of the unobserved wind mechanical power, phase angle, or angular velocity when measurements from only one of these variables are available. the immediate forecast of observed variables and predictions of unobserved variables can be used for effectively managing power grids ( electricity market clearing, regulation actions ) and early detection of abnormal behavior and faults. the physics - based gpr forecast time horizon depends on the combination of input ( wind power, load, etc. ) correlation time and characteristic ( relaxation ) time of the power grid and can be extended to short and medium - range times. | arxiv:1806.10990 |
we demonstrate that non - equilibrium electrons in thin nonmagnetic semiconductor layers or quantum dots can be fully spin polarized by means of simultaneous electrical spin injection and extraction. the complete spin polarization is achieved if the thin layers or quantum dots are placed between two ferromagnetic metal contacts with moderate spin injection coefficients and antiparallel magnetizations. the sign of the spin polarization is determined by the direction of the current. aplications of this effect in spintronics and quantum information processing are discussed. | arxiv:cond-mat/0506670 |
the heavy - tailed inter - event time distributions are widely observed in many human - activated systems, which may result from both endogenous mechanisms like the highest - priority - first protocol and exogenous factors like the varying global activity versus time. to distinguish the effects on temporal statistics from different mechanisms is this of theoretical significance. in this letter, we propose a new timing method by using a relative clock, where the time length between two consecutive events of an individual is counted as the number of other individuals ' events appeared during this interval. we propose a model, in which agents act either in a constant rate or with a power - law inter - event time distribution, and the global activity either keeps unchanged or varies periodically versus time. our analysis shows that the heavy tails caused by the heterogeneity of global activity can be eliminated by setting the relative clock, yet the heterogeneity due to real individual behaviors still exists. we perform extensive experiments on four large - scale systems, the search engine by aol, a social bookmarking system - - delicious, a short - message communication network, and a microblogging system - - twitter. strong heterogeneity and clear seasonality of global activity are observed, but the heavy tails cannot be eliminated by using the relative clock. our results suggest the existence of endogenous heterogeneity of human dynamics. | arxiv:1106.5562 |
using the exponentially diffuse boundary potential of green and lee ( 1955 ), we develop a mathematica notebook to treat alpha decay by using the complex energy approach of preston ( 1947 ), as modified by pierronne and marquez ( 1978 ). our approach allows the potential to change slowly from the well depth of the interior of the nucleus to the top of the coulomb barrier, rather than the sudden step of the simple square well used by pierronne and marquez. recent interest in possible variation in coupling constants such as the strong coupling alpha _ s motivates us to develop this algorithm which can allow numerical study of the variation of the decay constant of a nucleus such as u - 238 when the depth of the nuclear potential well changes. | arxiv:nucl-th/0206020 |
we propose a heisenberg - limited quantum interferometer whose input is twin optical beams from which one or more photons have been indistinguishably subtracted. such an interferometer can yield heisenberg - limited performance while at the same time giving a direct fringe reading, unlike for the twin - beam input of the holland - burnett interferometer. we propose a feasible experimental realization using a photon - number correlated source, such as non - degenerate parametric down - conversion, and perform realistic analyses of performance in the presence of loss and detector inefficiency. | arxiv:1707.07641 |
a new class of rings, the class of left localizable rings, is introduced. a ring $ r $ is left localizable if each nonzero element of $ r $ is invertible in some left localization $ s ^ { - 1 } r $ of the ring $ r $. explicit criteria are given for a ring to be a left localizable ring provided the ring has only finitely many maximal left denominator sets ( eg, this is the case if a ring has a left artinian left quotient ring ). it is proved that a ring with finitely many maximal left denominator sets is a left localizable ring iff its left quotient ring is a direct product of finitely many division rings. a characterization is given of the class of rings that are finite direct product of left localization maximal rings. | arxiv:1405.4552 |
we study the s = 1 / 2 heisenberg antiferromagnet on the pyrochlore lattice in the limit of strong easy - axis exchange anisotropy. we find, using only standard techniques of degenerate perturbation theory, that the model has a u ( 1 ) gauge symmetry generated by certain local rotations about the z - axis in spin space. upon addition of an extra local interaction in this and a related model with spins on a three - dimensional network of corner - sharing octahedra, we can write down the exact ground state wavefunction with no further approximations. using the properties of the soluble point we show that these models enter the u ( 1 ) spin liquid phase, a novel fractionalized spin liquid with an emergent u ( 1 ) gauge structure. this phase supports gapped s ^ z = 1 / 2 spinons carrying the u ( 1 ) ` ` electric ' ' gauge charge, a gapped topological point defect or ` ` magnetic ' ' monopole, and a gapless ` ` photon, ' ' which in spin language is a gapless, linearly dispersing s ^ z = 0 collective mode. there are power - law spin correlations with a nontrivial angular dependence, as well as novel u ( 1 ) topological order. this state is stable to all zero - temperature perturbations and exists over a finite extent of the phase diagram. using a convenient lattice version of electric - magnetic duality, we develop the effective description of the u ( 1 ) spin liquid and the adjacent soluble point in terms of gaussian quantum electrodynamics and calculate a few of the universal properties. the resulting picture is confirmed by our numerical analysis of the soluble point wavefunction. finally, we briefly discuss the prospects for understanding this physics in a wider range of models and for making contact with experiments. | arxiv:cond-mat/0305401 |
we study a simple model of the stochastic information filtering, in a randomly organized information system. for simplest versions of the model it appears to be possible to describe the filtering dynamics in terms of the master equations. exact analytical results for these equations and results of numerical investigation of the dynamical features of the filter are presented. | arxiv:cond-mat/0207608 |
the murchison widefield array ( mwa ) is a new low frequency radio telescope operating on the square kilometre array site in western australia. mwa is generating tens of terabytes of data daily. the size of the required data storage has become a significant operational limitation and cost. we present a simple binary compression technique and a system for the floating point visibility data developed mwa. we present the statistics of the impact of such compression on the data with the typical compression ratio up to 1 : 3. 1. | arxiv:1411.7088 |
multivariate multiple linear regression ( mmlr ), which occurs in a number of practical applications, generalizes traditional least squares ( multivariate linear regression ) to multiple right - hand sides. we extend recent mlr analyses to sketched mmlr in general schatten $ p $ - norms by interpreting the sketched problem as a multiplicative perturbation. our work represents an extension of maher ' s results on schatten $ p $ - norms. we derive expressions for the exact and perturbed solutions in terms of projectors for easy geometric interpretation. we also present a geometric interpretation of the action of the sketching matrix in terms of relevant subspaces. we show that a key term in assessing the accuracy of the sketched mmlr solution can be viewed as a tangent of a largest principal angle between subspaces under some assumptions. our results enable additional interpretation of the difference between an orthogonal and oblique projector with the same range. | arxiv:2007.06099 |
it has long been known that particles with short - range repulsive interactions in spatial dimension d = 1 form universal quantum liquids in the low density limit : all properties can be related to those of the spinless free fermi gas. previous renormalization group ( rg ) analyses demonstrated that this universality is described by an rg fixed point, infrared stable for d < 2, of the zero density gas. we show that for d > 2 the same fixed point describes the universal properties of particles with short - range attractive interactions near a feshbach resonance ; the fixed point is now infrared unstable, and the relevant perturbation is the detuning of the resonance. some exponents are determined exactly, and the same expansion in powers of ( d - 2 ) applies for scaling functions for d < 2 and d > 2. a separate exact rg analysis of a field theory of the particles coupled to ` molecules ' finds an alternative description of the same fixed point, with identical exponents ; this approach yields a ( 4 - d ) expansion which agrees with the recent results of nishida and son ( cond - mat / 0604500 ). the existence of the rg fixed point implies a universal phase diagram as a function of density, temperature, population imbalance, and detuning ; in particular, this applies to the bec - bcs crossover of fermions with s - wave pairing. our results open the way towards computation of these universal properties using the standard field - theoretic techniques of critical phenomena, along with a systematic analysis of corrections to universality. we also propose a 1 / n expansion ( based upon models with sp ( 2n ) symmetry ) of the fixed point and its vicinity, and use it to obtain results for the phase diagram. | arxiv:cond-mat/0609106 |
we combine the data from pamela and fermi - lat cosmic ray experiments by introducing a simple sum rule. this allows to investigate whether the lepton excess observed by these experiments is charge symmetric or not. we also show how the data can be used to predict the positron fraction at energies yet to be explored by the ams - 02 experiment. | arxiv:1105.0089 |
we consider a closed string field theory with an arbitrary matter current as a source of the closed string field. we find that the source must satisfy a constraint equation as a consequence of the brst invariance of the theory. we see that it corresponds to the covariant conservation law for the matter current, and the equation of motion together with this constraint equation determines the classical behavior of both the closed string field and the matter. we then consider the boundary state ( d - brane ) as an example of a source. we see that the ordinary boundary state cannot be a source of the closed string field when the string coupling g turns on. by perturbative expansion, we derive a recursion relation which represents the bulk backreaction and the d - brane recoil. we also make a comment on the rolling tachyon boundary state. | arxiv:hep-th/0309074 |
in this paper we study a feasibility - seeking problem with percentage violation constraints. these are additional constraints, that are appended to an existing family of constraints, which single out certain subsets of the existing constraints and declare that up to a specified fraction of the number of constraints in each subset is allowed to be violated by up to a specified percentage of the existing bounds. our motivation to investigate problems with percentage violation constraints comes from the field of radiation therapy treatment planning wherein the fully - discretized inverse planning problem is formulated as a split feasibility problem and the percentage violation constraints give rise to non - convex constraints. following the cq algorithm of byrne ( 2002, inverse problems, vol. 18, pp. 441 - 53 ), we develop a string - averaging cq method that uses only projections onto the individual sets which are half - spaces represented by linear inequalities. the question of extending our theoretical results to the non - convex sets case is still open. we describe how our results apply to radiation therapy treatment planning and provide a numerical example. | arxiv:1911.12041 |
we study transport through a ferromagnetic single - electron transistor. the resistance is represented as a path integral, so that systems where the tunnel resistances are smaller than the quantum resistance can be investigated. beyond the low order sequential tunneling and co - tunneling regimes, a large magnetoresistance ratio at sufficiently low temperatures is found. in the opposite limit, when the thermal energy is larger than the charging energy, the magnetoresistance ratio is only slightly enhanced. | arxiv:cond-mat/9908061 |
in this paper we study the analytic torsion and the $ l ^ 2 $ - torsion of compact locally symmetric manifolds. we consider the analytic torsion with respect to representations of the fundamental group which are obtained by restriction of irreducible representations of the group of isometries of the underlying symmetric space. the main purpose is to study the asymptotic behavior of the analytic torsion with respect to sequences of representations associated to rays of highest weights. | arxiv:1204.0659 |
monolayer phosphorene provides a unique two - dimensional ( 2d ) platform to investigate the fundamental many - body interactions. however, owing to its high instability, unambiguous identification of monolayer phosphorene has been elusive. consequently, many important fundamental properties, such as exciton dynamics, remain underexplored. we report a rapid, noninvasive, and highly accurate approach based on optical interferometry to determine the layer number of phosphorene, and confirm the results with reliable photoluminescence measurements. based on the measured optical gap and the calculated electronic energy gap, we determined the exciton binding energy to be ~ 0. 4 ev for the monolayer phosphorene on sio2 / si substrate, which agrees well with theoretical predictions. our results open new avenues for exploring fundamental phenomena and novel optoelectronic applications using monolayer phosphorene. | arxiv:1412.6701 |
in a recent note w. kohnen asks whether the values of dedekind sums are dense in the field of $ p $ - adic numbers. the present paper answers this question. dedekind sums do not approximate units of $ \ mathbb z _ 2 $ or $ \ mathbb z _ 3 $, so they are not dense in $ \ mathbb q _ 2 $ or $ \ mathbb q _ 3 $. but they are dense in $ \ mathbb q _ p $ if $ p \ ge 5 $. | arxiv:1609.03162 |
by extending our self - consistent mhd simulations for the solar wind, we study the evolution of stellar winds of solar - type stars from early main sequence stage to red giant phase. young solar - type stars are active and the mass loss rates are larger by up to ~ 100 times than that of the present - day sun. we investigate how the stellar wind is affected when the magnetic field strength and fluctuation amplitude at the photosphere increase. while the mass loss rate sensitively depends on the input energy from the surface because of the global instability related to the reflection and nonlinear dissipation of alfven waves, it saturates at ~ 100 times because most of the energy is used up for the radiative losses rather than the kinetic energy of the wind. after the end of the main sequence phase when the stellar radius expands by ~ 10 times, the steady hot corona with temperature $ 10 ^ 6 $ k, suddenly disappears. chromospheric materials, with hot bubbles embedded owing to thermal instability, directly stream out ; the red giant wind is not a steady stream but structured outflow. | arxiv:1301.2359 |
we discuss the idea of maximal jets introduced by falcke & biermann in 1995. according to it, the maximum possible jet power in its internal energy equals the kinetic power in its rest mass. we show this result is incorrect because of an unfortunate algebraic mistake. | arxiv:1512.08871 |
behavior models form an integral component of digital twins. the specific characteristics of these models may vary depending on the use case. one of these key characteristics is the modeling depth. behavior models with a lower modeling depth depict the behavior of the asset in an abstract way, while those with a higher modeling depth depict the behavior in detail. even if very detailed behavior models are flexible and realistic, they also require a lot of resources such as computing power, simulation time and memory requirements. in some applications, however, only limited resources are available. the automated creation of digital twins is of crucial importance for their widespread use. although there are methods for the automated creation of behavior models for digital twins with a specific modeling depth, there is currently no method for the automated creation of behavior models with varying modeling depths. this article presents such an approach and demonstrates its advantages using two industrial use cases. it is demonstrated that the automatically created behavior models of lower modeling depth yield results that are almost identical to those of models with a higher modeling depth, but with significantly reduced computing time and required memory. this enables the efficient use of behavior models in a variety of use cases, regardless of the availability of resources. | arxiv:2411.07883 |
the subtle relation of the marginality of dirac model and the emergence of the hopf term through a yukawa - type interaction is revealed in this work. we show that the improvement of the marginality of dirac mode through an infinitesimal non - relativistic term, which is irrelevant for renormalization group, is necessary to emerge the hopf term. it is found that the appearance of the hopf term is always accompanied with chiral boundary modes, and the sign of the coupling constant of the infinitesimal non - relativistic term decides their chirality. a lattice dirac model is also constructed to realize the hopf term. | arxiv:1303.3295 |
thermoelectric materials convert heat into electricity through thermally driven charge transport in solids, or vice versa for cooling. to be competitive with conventional energy - generation technologies, a thermoelectric material must possess the properties of both an electrical conductor and a thermal insulator. however, these properties are normally mutually exclusive because of the interconnection of the scattering mechanisms for charge carriers and phonons. recent theoretical investigations on sub - device scales have revealed that silicon membranes covered by nanopillars exhibit a multitude of local phonon resonances, spanning the full spectrum, that couple with the heat - carrying phonons in the membrane and collectively cause a reduction in the in - plane thermal conductivity $ - $ while, in principle, not affecting the electrical properties because the nanopillars are external to the pathway of voltage generation and charge transport. here this effect is demonstrated experimentally for the first time by investigating device - scale suspended silicon membranes with gan nanopillars grown on the surface. the nanopillars cause up to 21 % reduction in the thermal conductivity while the electrical conductivity and the seebeck coefficient remain unaffected, thus demonstrating an unprecedented decoupling in the semiconductor ' s thermoelectric properties. the measured thermal conductivity behavior for coalesced nanopillars and corresponding lattice - dynamics calculations provide further evidence that the reductions are mechanistically tied to the phonon resonances. this finding breaks a longstanding trade - off between competing properties in thermoelectricity and paves the way for engineered high - efficiency solid - state energy recovery and cooling. | arxiv:2301.04769 |
in this paper, we investigate the effect of tdd, as compared to a non - tdd approach, as well as its retainment ( or retention ) over a time span of ( about ) six months. to pursue these objectives, we conducted a ( quantitative ) longitudinal cohort study with 30 novice developers ( i. e., third - year undergraduate students in computer science ). we observed that tdd affects neither the external quality of software products nor developers ' productivity. however, we observed that the participants applying tdd produced significantly more tests, with a higher fault - detection capability than those using a non - tdd approach. as for the retainment of tdd, we found that tdd is retained by novice developers for at least six months. | arxiv:2105.03312 |
in these proceedings we summarise how the determinantal structure for the conditional overlaps among left and right eigenvectors emerges in the complex ginibre ensemble at finite matrix size. an emphasis is put on the underlying structure of orthogonal polynomials in the complex plane and its analogy to the determinantal structure of $ k $ - point complex eigenvalue correlation functions. the off - diagonal overlap is shown to follow from the diagonal overlap conditioned on $ k \ geq2 $ complex eigenvalues. as a new result we present the local bulk scaling limit of the conditional overlaps away from the origin. it is shown to agree with the limit at the origin and is thus universal within this ensemble. | arxiv:1912.09339 |
depression is a common psychiatric disorder, which causes significant patient distress. bipolar disorder is characterized by mood fluctuations between depression and mania. unipolar and bipolar depression can be easily confused because of similar symptom profiles, but their adequate treatment plans are different. therefore, a precise data - driven diagnosis is essential for successful treatment. in order to aid diagnosis, research applied machine learning to brain imaging data, in particular to electroencephalography ( eeg ), with accuracies reaching 99. 5 % ( unipolar vs. healthy ) or 85 % ( bipolar vs. healthy ). however, these results arise from small training sets, without validation on independent data, and thus have a high risk of inflated accuracies due to data over - fitting. we propose to use a bigger corpus of realistic clinical data for training and testing and improve classification with microstates features, which can assess the function of large - scale brain networks. | arxiv:1908.11217 |
we study the intrinsic large - scale distribution and evolution of seven ionized metals in the illustristng magneto - hydrodynamical cosmological simulation. we focus on the fractions of c \, \ textsc { ii }, c \, \ textsc { iv }, mg \, \ textsc { ii }, n \, \ textsc { v }, ne \, \ textsc { viii }, o \, \ textsc { vi }, and si \, \ textsc { iv } in different cosmic web structures ( filaments, haloes, and voids ) and gas phases ( warm - hot intergalactic medium whim, hot, diffuse, and condensed gas ) from $ z = 6 $ to $ z = 0 $. our analysis provides a new perspective to the study of the distribution and evolution of baryons across cosmic time while offering new hints in the context of the well - known missing baryons problem. the cosmic web components are here identified using the local comoving dark matter density, which provides a simple but effective way of mapping baryons on large scales. our results show that c \, \ textsc { ii } and mg \, \ textsc { ii } are mostly located in condensed gas inside haloes in high - density and low - temperature star - forming regions ( $ \ rho _ { \ rm gas } / \ bar { \ rho } _ { \ rm bar } \ gtrsim10 ^ 3 $, and $ { \ rm t } \ lesssim10 ^ { 5 } $ ~ k ). c \, \ textsc { iv } and si \, \ textsc { iv } present similar evolution of their mass fractions in haloes and filaments across cosmic time. in particular, their mass budgets in haloes in condensed phase ( $ \ rho _ { \ rm gas } / \ bar { \ rho } _ { \ rm bar } \ gtrsim10 ^ 3 $, and $ { \ rm t } \ lesssim10 ^ { 5 } $ ~ k ) are driven by gas cooling and star formation with a peak at $ z \ sim2 $. finally, our results confirm that o \, \ textsc { vi }, ne \, \ textsc { viii }, and n \, \ textsc { v } are good tracers of warm / hot and low - density gas at low redshift ( $ \ | arxiv:2102.01092 |
recent studies on analyzing dynamic brain connectivity rely on sliding - window analysis or time - varying coefficient models which are unable to capture both smooth and abrupt changes simultaneously. emerging evidence suggests state - related changes in brain connectivity where dependence structure alternates between a finite number of latent states or regimes. another challenge is inference of full - brain networks with large number of nodes. we employ a markov - switching dynamic factor model in which the state - driven time - varying connectivity regimes of high - dimensional fmri data are characterized by lower - dimensional common latent factors, following a regime - switching process. it enables a reliable, data - adaptive estimation of change - points of connectivity regimes and the massive dependencies associated with each regime. we consider the switching var to quantity the dynamic effective connectivity. we propose a three - step estimation procedure : ( 1 ) extracting the factors using principal component analysis ( pca ) and ( 2 ) identifying dynamic connectivity states using the factor - based switching vector autoregressive ( var ) models in a state - space formulation using kalman filter and expectation - maximization ( em ) algorithm, and ( 3 ) constructing the high - dimensional connectivity metrics for each state based on subspace estimates. simulation results show that our proposed estimator outperforms the k - means clustering of time - windowed coefficients, providing more accurate estimation of regime dynamics and connectivity metrics in high - dimensional settings. applications to analyzing resting - state fmri data identify dynamic changes in brain states during rest, and reveal distinct directed connectivity patterns and modular organization in resting - state networks across different states. | arxiv:1701.06754 |
owing to their chiral cubic structure, exotic multifold topological excitations have been predicted and recently observed in transition metal silicides like $ \ beta $ - rhsi. herein, we report that the topological character of rhsi is also observed in its orthorhombic $ \ alpha $ - phase which displays multiple types of dirac nodes very close to the fermi level ( $ \ varepsilon _ f $ ) with the near absence of topologically trivial carriers. we discuss the symmetry analysis, band connectivity along high - symmetry lines using group representations, the band structure, and the nature of the dirac points and nodal lines occurring near $ \ varepsilon _ f $. the de haas - van alphen effect ( dhva ) indicates a fermi surface in agreement with the calculations. we find an elliptically - shaped nodal line very close to $ \ varepsilon _ f $ around and near the $ s $ - point on the $ k _ y - k _ z $ plane that results from the intersection of two upside - down dirac cones. the two dirac points of the participating kramers degenerate bands are only 5 mev apart, hence an accessible magnetic field might induce a crossing between the spin - up partner of the upper - dirac cone and the spin - down partner of the lower dirac cone, possibly explaining the anomalies observed in the magnetic torque. | arxiv:2002.03020 |
in explainable constraint solving ( xcs ), it is common to extract a minimal unsatisfiable subset ( mus ) from a set of unsatisfiable constraints. this helps explain to a user why a constraint specification does not admit a solution. finding muses can be computationally expensive for highly symmetric problems, as many combinations of constraints need to be considered. in the traditional context of solving satisfaction problems, symmetry has been well studied, and effective ways to detect and exploit symmetries during the search exist. however, in the setting of finding muses of unsatisfiable constraint programs, symmetries are understudied. in this paper, we take inspiration from existing symmetry - handling techniques and adapt well - known mus - computation methods to exploit symmetries in the specification, speeding - up overall computation time. our results display a significant reduction of runtime for our adapted algorithms compared to the baseline on symmetric problems. | arxiv:2412.13606 |
typical end - to - end formulations for learning robotic navigation involve predicting a small set of steering command actions ( e. g., step forward, turn left, turn right, etc. ) from images of the current state ( e. g., a bird ' s - eye view of a slam reconstruction ). instead, we show that it can be advantageous to learn with dense action representations defined in the same domain as the state. in this work, we present " spatial action maps, " in which the set of possible actions is represented by a pixel map ( aligned with the input image of the current state ), where each pixel represents a local navigational endpoint at the corresponding scene location. using convnets to infer spatial action maps from state images, action predictions are thereby spatially anchored on local visual features in the scene, enabling significantly faster learning of complex behaviors for mobile manipulation tasks with reinforcement learning. in our experiments, we task a robot with pushing objects to a goal location, and find that policies learned with spatial action maps achieve much better performance than traditional alternatives. | arxiv:2004.09141 |
among all public transit modes, bus transit systems stand out as the most prevalent and popular. this prominence has spurred a significant body of research addressing various aspects of bus systems. in the literature, analytical approaches and mathematical programming are predominantly used to explore the public bus transit network design problem and operations planning ( pbtndp & op ). part i of our study presented statistical analyses of literature applying these methodologies to pbtndp & op, along with a comprehensive review of analytical papers, highlighting the strengths and weaknesses of each approach. in part ii, we delve into the applications of mathematical programming within pbtndp & op, building upon the 15 major sub - categories identified in part i. we have critically analyzed the identified papers within these sub - categories from various perspectives, including the problems investigated, modeling methods employed, decision variables, network structures, and key findings. this critical review highlights selected papers in each category. finally, acknowledging existing research gaps, we propose potential extensions for future research. despite the extensive array of publications, numerous topics still warrant further exploration. notably, sustainable pbtndp & op and challenges associated with integrating emerging technologies are poised to dominate future research agendas. | arxiv:2502.19430 |
maxwell ' s mature presentation of his equations emphasized the unity of electromagnetism and mechanics, subsuming both as " dynamical systems ". that intuition of unity has proved both fruitful, as a source of pregnant concepts, and broadly inspiring. a deep aspect of maxwell ' s work is its use of redundant potentials, and the associated requirement of gauge symmetry. those concepts have become central to our present understanding of fundamental physics, but they can appear to be rather formal and esoteric. here i discuss two things : the physical significance of gauge invariance, in broad terms ; and some tantalizing prospects for further unification, building on that concept, that are visible on the horizon today. if those prospects are realized, maxwell ' s vision of the unity of field and substance will be brought to a new level. | arxiv:1512.02094 |
we consider a quantum model of a nanomechanical flexing beam resonator interacting with a bath comprising a few damped tunneling two level systems ( tls ' s ). in contrast with a resonator interacting bilinearly with an ohmic free oscillator bath ( modeling clamping loss, for example ), the mechanical resonator damping is amplitude dependent, while the decoherence of quantum superpositions of mechanical position states depends only weakly on their spatial separation. | arxiv:0907.0431 |
we study picard ' s exceptional values of holomorphic one - parametric families of entire functions. our first result shows that the set of parameter values for which zero is a picard value can be an arbitrary closed set of zero logarithmic capacity. this answers a question of julia. second, we show that if a function has a picard exceptional value for all values of parameter in some region of the plane then this picard value is a holomorphic function in the complement of some discrete set e, tending to infinity as the papameter tends to e. | arxiv:math/0503750 |
avid technology, inc. is a global technology company headquartered in burlington, massachusetts, and was founded in august 1987 by bill warner. it develops software, saas, and hardware products used in media and entertainment. = = history = = avid was founded by bill warner, a former marketing manager from apollo computer. a prototype of their first non - linear editing system, the avid / 1 media composer, was shown at the national association of broadcasters ( nab ) convention in april 1988. the avid / 1 was based on an apple macintosh ii computer, with special hardware and software of avid ' s design installed. the avid / 1 was " the biggest shake - up in editing since melies played with time and sequences in the early 1900s ". by the early 1990s, avid products began to replace such tools as the moviola, steenbeck, and kem flatbed editors, allowing editors to handle their film creations with greater ease. the first feature film edited using the avid was let ' s kill all the lawyers in 1992, directed by ron senkowski. the film was edited at a 30fps ntsc rate, then used avid mediamatch to generate a negative cutlist from the edl. the first feature film edited natively at 24fps with what was to become the avid film composer was emerson park. the first studio film to be edited at 24fps was lost in yonkers, directed by martha coolidge. by 1994 only three feature films used the new digital editing system. by 1995 dozens had switched to avid, and it signaled the beginning of the end of cutting celluloid. in 1996 walter murch accepted the academy award for editing the english patient ( which also won best picture ), which he cut on the avid. this was the first editing oscar awarded to a digitally edited film ( although the final print was still created with traditional negative cutting ). in 1994 avid introduced open media framework ( omf ) as an open standard file format for sharing media and related metadata. over the years, avid has released numerous freeware versions of media composer. initially this included avid free dv : a free edition of media composer with limited functionality ; avid xpress dv : a consumer edition of media composer ; and then avid xpress pro : a prosumer edition of media composer. these editions were discontinued in 2008 as the flagship media composer was lowered in price. later, avid released media composer | first, which included a large portion of media composer ' s functionality but its exporting workflows publishing | https://en.wikipedia.org/wiki/Avid_Technology |
we use lattice qcd calculations of fluctuations and correlations of various conserved charges to show that the deconfinement of strangeness takes place in the chiral crossover region of qcd ; however, inside the quark - gluon plasma strange quarks remain strongly interacting at least up to temperatures twice the qcd crossover temperature. further, we discuss how the freeze - out parameters of heavy - ion collisions can be determined in a model - independent way through direct comparisons between experimentally measured higher order cumulants of conserved charges and corresponding lattice qcd calculations. utilizing the preliminary data from the star and phenix experiments we illustrate this method. although, the lattice qcd based determinations of the freeze - out parameters utilizing data sets of different experiments and different observables are currently not consistent with each other, it is tantalizing to see that all the observed freeze - out parameters lie very close to the chiral / deconfinement crossover region of qcd. | arxiv:1307.6255 |
we provide sufficient conditions which ensure that the intrinsic martingale in the supercritical branching random walk converges exponentially fast to its limit. the case of galton - watson processes is particularly included so that our results can be seen as a generalization of a result given in the classical treatise by asmussen and hering. as an auxiliary tool, we prove ultimate versions of two results concerning the exponential renewal measures which may be interesting on its own and which correct, generalize and simplify some earlier works. | arxiv:0910.4246 |
we study the calculation of exact p - values for a large class of non - sharp null hypotheses about treatment effects in a setting with data from experiments involving members of a single connected network. the class includes null hypotheses that limit the effect of one unit ' s treatment status on another according to the distance between units ; for example, the hypothesis might specify that the treatment status of immediate neighbors has no effect, or that units more than two edges away have no effect. we also consider hypotheses concerning the validity of sparsification of a network ( for example based on the strength of ties ) and hypotheses restricting heterogeneity in peer effects ( so that, for example, only the number or fraction treated among neighboring units matters ). our general approach is to define an artificial experiment, such that the null hypothesis that was not sharp for the original experiment is sharp for the artificial experiment, and such that the randomization analysis for the artificial experiment is validated by the design of the original experiment. | arxiv:1506.02084 |
we study the relation between torsion tensors of principal connections on g - structures and characteristic conic connections on associated cone structures. we formulate sufficient conditions under which the existence of a characteristic conic connection implies the existence of a torsion - free principal connection. we verify these conditions for adjoint varieties of simple lie algebras, excluding those of type $ \ textsf { a } _ { \ ell \ neq 2 } $ or $ \ textsf { c } _ { \ ell } $. as an application, we give a complete classification of the germs of minimal rational curves whose vmrt at a general point is such an adjoint variety : nontrivial ones come from lines on hyperplane sections of certain grassmannians or minimal rational curves on wonderful group compactifications. | arxiv:2407.16263 |
we summarize the different puzzles raised by aging experiments of spin - glasses and their various interpretations. we try to reconcile the ` real space ', droplet like pictures with the hierarchical pictures that have been proposed in the past. the basic ingredient is a strong separation of the time scales that govern the dynamics of the system on different length scales. changing the temperature changes the length scale at which the system is observed, thereby allowing rejuvenation ( that concerns short length scales ) and memory ( stored in long length scales ) to coexist. we show that previous experiments can be reanalyzed in terms of { \ it vanishing energy barriers } at the spin - glass transition, an important ingredient to obtain a fast separation of time scales. we propose to distinguish between ` fixed landscape rejuvenation ', which is already present in simple two ( or multi ) level systems, from the ` strong ' chaos effect on scales larger than an ` overlap length ' conjectured in the context of the droplet model. we argue that most experiments can be accounted for without invoking the existence of an overlap length. new experiments are presented to test some recent predictions of the strong chaos scenario, with negative results. | arxiv:cond-mat/0106539 |
we employ a novel discrete element method ( dem ) force formulation to simulate adhesive wear and assess the effects of material and loading parameters on the properties of the third - body layer ( tbl ) formed during sliding motion. the study emphasizes the role of a material ' s critical length scale d * in the rheology of the tbl. this critical length scale is already known for controlling the size of smallest wear particles. we observe the emergence of a several wear regimes involving wear particle creation and aggregation, with limited effect from d * on tbl properties. instead, material strength and surface energy have a profound influence. this study opens up new avenues for exploration of larger systems, three - dimensional setups, and other loading conditions. | arxiv:2304.14783 |
comparative and evolutive ecologists are interested in the distribution of quantitative traits among related species. the classical framework for these distributions consists of a random process running along the branches of a phylogenetic tree relating the species. we consider shifts in the process parameters, which reveal fast adaptation to changes of ecological niches. we show that models with shifts are not identifiable in general. constraining the models to be parsimonious in the number of shifts partially alleviates the problem but several evolutionary scenarios can still provide the same joint distribution for the extant species. we provide a recursive algorithm to enumerate all the equivalent scenarios and to count the effectively different scenarios. we introduce an incomplete - data framework and develop a maximum likelihood estimation procedure based on the em algorithm. finally, we propose a model selection procedure, based on the cardinal of effective scenarios, to estimate the number of shifts and prove an oracle inequality. | arxiv:1508.00225 |
in recent years, multi - label classification problem has become a controversial issue. in this kind of classification, each sample is associated with a set of class labels. ensemble approaches are supervised learning algorithms in which an operator takes a number of learning algorithms, namely base - level algorithms and combines their outcomes to make an estimation. the simplest form of ensemble learning is to train the base - level algorithms on random subsets of data and then let them vote for the most popular classifications or average the predictions of the base - level algorithms. in this study, an ensemble learning method is proposed for improving multi - label classification evaluation criteria. we have compared our method with well - known base - level algorithms on some data sets. experiment results show the proposed approach outperforms the base well - known classifiers for the multi - label classification problem. | arxiv:1801.02149 |
structural, electronic, and transport properties of scnisb, scpdsb, and scptsb were investigated from first principles. electronic band structures derived within the fully relativistic mbjlda approach were compared with those obtained from the standard gga calculations. all the compounds studied exhibit indirect narrow band gaps ( 0. 24 - 0. 63 ev ). the effective masses of hole - like carriers are relatively small ( 0. 27 - 0. 36 ), and decrease with an increasing atomic number of the transition metal component. the carrier relaxation time, required for realistic calculations of the electrical conductivity, was approximated within the deformation potential theory. the gga approach yielded overestimated transport characteristics with respect to those derived within the mbjlda analysis. the largest power factor of 4 - 6 mwk ^ - 2m ^ - 1 ) at high temperatures was obtained for scptsb. this value is comparable with those observed experimentally for fe - nb - sb half - heusler alloys, and hence makes scptsb a very good candidate material for thermoelectric applications. | arxiv:1804.08423 |
rhythms and vibrations represent the quintessence of life, they are ubiquitous ( systemic ) in all living systems. recognising, unfolding these rhythms is paramount in medicine, for example in the physiology of the heart, lung, hearing, speech, brain, the cellular and molecular processes involved in biological clocks. the importance of the commensurability of the frequencies in different rhythms has been thoroughly studied in music. we define a log - frequency correlation measure on spectral densities that gives the temporal evolution of the distribution of frequency ratios ( rational or irrational ) in between two signals, using analytic wavelets. we illustrate these concepts on numerical signals ( sums of sine functions ) and voice recordings from the voice - icar - federico ii database. finally, with a second correlation operation from two of these ratio distributions ( a reference one, the other from the voices ) we introduce another quantity that we call \ emph { sonance }, measuring the ` ` harmony ' ' ( rationality ) of two voices sung together as a function of a pitch transposition. | arxiv:2110.13910 |
program synthesis from incomplete specifications ( e. g. input - output examples ) has gained popularity and found real - world applications, primarily due to its ease - of - use. since this technology is often used in an interactive setting, efficiency and correctness are often the key user expectations from a system based on such technologies. ensuring efficiency is challenging since the highly combinatorial nature of program synthesis algorithms does not fit in a 1 - 2 second response expectation of a user - facing system. meeting correctness expectations is also difficult, given that the specifications provided are incomplete, and that the users of such systems are typically non - programmers. in this paper, we describe how interactivity can be leveraged to develop efficient synthesis algorithms, as well as to decrease the cognitive burden that a user endures trying to ensure that the system produces the desired program. we build a formal model of user interaction along three dimensions : incremental algorithm, step - based problem formulation, and feedback - based intent refinement. we then illustrate the effectiveness of each of these forms of interactivity with respect to synthesis performance and correctness on a set of real - world case studies. | arxiv:1703.03539 |
we provide new examples of translation actions on locally compact groups with the " local spectral gap property " introduced in \ cite { bisg15 }. this property has applications to strong ergodicity, the banach - ruziewicz problem, orbit equivalence rigidity, and equidecomposable sets. the main group of study here is the group $ \ text { isom } ( \ mathbb { r } ^ d ) $ of orientation - preserving isometries of the euclidean space $ \ mathbb { r } ^ d $, for $ d \ geq 3 $. we prove that the translation action of a countable dense subgroup $ \ gamma $ on isom $ ( \ mathbb r ^ d ) $ has local spectral gap, whenever the translation action of the rotation projection of $ \ gamma $ on $ \ text { so } ( d ) $ has spectral gap. our proof relies on the amenability of $ \ text { isom } ( \ mathbb { r } ^ d ) $ and on work of lindenstrauss and varj \ ' u, \ cite { lv14 }. | arxiv:1702.06323 |
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