text
stringlengths 1
3.65k
| source
stringlengths 15
79
|
|---|---|
we present a finite - temperature theory of the anisotropic spin - spin correlations in magnetic metallic monolayers, deposited on a suitable substrate. the ` spins ' are the local moments set up by the itinerant electrons, and the key concept is the relativistic disordered local moment state, which represents the paramagnetic state of a set of local moments. the spin - spin correlations between these local moments are then extracted using the linear response formalism. the anisotropy is included in a fully relativistic treatment, based on the dirac equation, and has a qualitative impact on noncollinear magnetic states, by lifting their chiral degeneracy. the theory is applied to mn monolayers on the hexagonal ( 111 ) surfaces of pd, pt, ag and au. the presence of competing exchange interactions is highlighted by choosing different substrates, which favour either the row - wise antiferromagnetic state or the chiral triangular n \ ' eel state. we correlate the electronic structure with the magnetic properties, by comparing filled with partially filled substrate d - - bands, and low vs high atomic number. the disagreement between theory and experiment for mn $ _ 1 $ / ag ( 111 ) is addressed, and the nature of the magnetic domains found experimentally is suggested to be chiral.
|
arxiv:1010.5135
|
the aim of this paper is to show that, in various situations, the only continuous linear map that transforms a convolution product into a pointwise product is a fourier transform. we focus on the cyclic groups $ \ z / nz $, the integers $ \ z $, the torus $ \ t $ and the real line. we also ask a related question for the twisted convolution.
|
arxiv:0912.3129
|
a variety of homologous carbon chains ( hcnh, hcnn, cns, cno, and ocno ) are found to exhibit an appealing even - odd effect. chains containing a number of carbon atoms of a certain parity possess singlet ground states, while members of opposite parity have triplet ground states. from a general perspective, it is important that this even - odd effect confounds straightforward chemical intuition. whether the most stable form is a triplet or a singlet is neither simply related to the fact that the species in question is a normal ( closed - shell, nonradical ) molecule nor a ( di ) radical or to the ( e. g., cumulene - type ) c - c bond succession across the chain. from a computational perspective, the present results are important also because they demonstrate that electron correlations in carbon - based chains are extremely strong. whether the gold - standard ccsd ( t ) ( coupled - cluster expansions with single and double excitations and triple excitations corrections ) framework suffices to describe such strongly correlated systems remains an open question that calls for further clarification. most importantly for astrochemistry, the present results may explain why certain members are not astronomically observed although larger members of the same homologous series are detected ; the missing species are exactly those for which the present calculations predict triplet ground states.
|
arxiv:2110.11071
|
automotive engineering, along with aerospace engineering and naval architecture, is a branch of vehicle engineering, incorporating elements of mechanical, electrical, electronic, software, and safety engineering as applied to the design, manufacture and operation of motorcycles, automobiles, and trucks and their respective engineering subsystems. it also includes modification of vehicles. manufacturing domain deals with the creation and assembling the whole parts of automobiles is also included in it. the automotive engineering field is research intensive and involves direct application of mathematical models and formulas. the study of automotive engineering is to design, develop, fabricate, and test vehicles or vehicle components from the concept stage to production stage. production, development, and manufacturing are the three major functions in this field. = = disciplines = = = = = automobile engineering = = = automobile engineering is a branch study of engineering which teaches manufacturing, designing, mechanical mechanisms as well as operations of automobiles. it is an introduction to vehicle engineering which deals with motorcycles, cars, buses, trucks, etc. it includes branch study of mechanical, electronic, software and safety elements. some of the engineering attributes and disciplines that are of importance to the automotive engineer include : safety engineering : safety engineering is the assessment of various crash scenarios and their impact on the vehicle occupants. these are tested against very stringent governmental regulations. some of these requirements include : seat belt and air bag functionality testing, front and side - impact testing, and tests of rollover resistance. assessments are done with various methods and tools, including computer crash simulation ( typically finite element analysis ), crash - test dummy, and partial system sled and full vehicle crashes. fuel economy / emissions : fuel economy is the measured fuel efficiency of the vehicle in miles per gallon or kilometers per liter. emissions - testing covers the measurement of vehicle emissions, including hydrocarbons, nitrogen oxides ( nox ), carbon monoxide ( co ), carbon dioxide ( co2 ), and evaporative emissions. nvh engineering ( noise, vibration, and harshness ) : nvh involves customer feedback ( both tactile [ felt ] and audible [ heard ] ) concerning a vehicle. while sound can be interpreted as a rattle, squeal, or hot, a tactile response can be seat vibration or a buzz in the steering wheel. this feedback is generated by components either rubbing, vibrating, or rotating. nvh response can be classified in various ways : powertrain nvh, road noise, wind noise, component noise, and squeak and rattle. note, there are both good
|
https://en.wikipedia.org/wiki/Automotive_engineering
|
the goal of filter pruning is to search for unimportant filters to remove in order to make convolutional neural networks ( cnns ) efficient without sacrificing the performance in the process. the challenge lies in finding information that can help determine how important or relevant each filter is with respect to the final output of neural networks. in this work, we share our observation that the batch normalization ( bn ) parameters of pre - trained cnns can be used to estimate the feature distribution of activation outputs, without processing of training data. upon observation, we propose a simple yet effective filter pruning method by evaluating the importance of each filter based on the bn parameters of pre - trained cnns. the experimental results on cifar - 10 and imagenet demonstrate that the proposed method can achieve outstanding performance with and without fine - tuning in terms of the trade - off between the accuracy drop and the reduction in computational complexity and number of parameters of pruned networks.
|
arxiv:2112.01155
|
in this paper, we consider a diffusion equation with fractional - time derivative with nonsingular mittag - leffler kernel in hilbert spaces. existence and uniqueness of solution are proved by means of a spectral argument. the existence of solution is obtained for all values of the fractional parameter $ \ alpha \ in ( 0, 1 ) $. moreover, by applying control theory to the fractional diffusion problem we obtain an optimality system which has also a unique solution.
|
arxiv:1711.09070
|
we consider, for real abelian fields k, the birch - - tate formula linking the tame kernel \ # k \ _ 2 ( z \ _ k ) to $ \ zeta $ \ _ k ( - 1 ) ; we compare, for quadratic and cyclic cubic fields with p = 2, 3, \ # k \ _ 2 ( \ bz \ _ k ) [ p ^ $ \ infty $ ] to the order of the torsion group t \ _ { k, p } of abelian p - ramification theory given by the residue of $ \ zeta $ \ _ { k, p } ( s ) at s = 1. this is done via the ` ` genus theory ' ' of p - adic pseudo - measures, inaugurated in the 1970 / 80 ' s and the fact that t \ _ { k, p } only depends on the p - class group and on the normalized p - adic regulator of k ( theorem a ). we apply this to prove a conjecture of deng - - li giving the structures of k \ _ 2 ( z \ _ k ) [ 2 ^ $ \ infty $ ] for an interesting family of real quadratic fields ( theorem b ). then, for p > 3, we give a lower bound of the p - rank of k \ _ 2 ( \ bz \ _ k ) in cyclic p - extensions ( theorem c ). complements, pari programs and tables are given in an appendix.
|
arxiv:2310.10112
|
we search for gravitational - wave signals associated with gamma - ray bursts detected by the fermi and swift satellites during the second half of the third observing run of advanced ligo and advanced virgo ( 1 november 2019 15 : 00 utc - 27 march 2020 17 : 00 utc ). we conduct two independent searches : a generic gravitational - wave transients search to analyze 86 gamma - ray bursts and an analysis to target binary mergers with at least one neutron star as short gamma - ray burst progenitors for 17 events. we find no significant evidence for gravitational - wave signals associated with any of these gamma - ray bursts. a weighted binomial test of the combined results finds no evidence for sub - threshold gravitational wave signals associated with this grb ensemble either. we use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each gamma - ray burst. finally, we constrain the population of low luminosity short gamma - ray bursts using results from the first to the third observing runs of advanced ligo and advanced virgo. the resulting population is in accordance with the local binary neutron star merger rate.
|
arxiv:2111.03608
|
we prove two principal results. firstly, we characterise maass forms in terms of functional equations for dirichlet series twisted by primitive characters. the key point is that the twists are allowed to be meromorphic. this weakened analytic assumption applies in the context of our second theorem, which shows that the quotient of the symmetric square l - function of a maass newform and the riemann zeta function has infinitely many poles.
|
arxiv:1809.06586
|
we show that the correlation functions of ghosts and gluons for the pure yang - mills theory in landau gauge can be accurately reproduced for all momenta by a one - loop calculation. the key point is to use a massive extension of the faddeev - popov action. the agreement with lattice simulation is excellent in d = 4. the one - loop calculation also reproduces all the characteristic features of the lattice simulations in d = 3 and naturally explains the pecularities of the propagators in d = 2.
|
arxiv:1004.1607
|
in this letter, we discuss the wheeler - dewitt equation with an ordering parameter in the friedmann - robertson - walker universe. the solutions when the universe was very small and at the end of the expansion are obtained in terms of bessel and heun functions, respectively. we also obtain a boundary condition which should be satisfied by the ordering parameter, namely, $ 0 \ leq p \ leq 2 $. we investigate the minimum value of the scale factor with respect to the maximum value of the probability density.
|
arxiv:2003.13377
|
for low - mass ( frequency $ \ ll $ ghz ) axions, dark matter detection experiments searching for an axion - photon - photon coupling generally have suppressed sensitivity, if they use a static background magnetic field. this geometric suppression can be alleviated by using a high - frequency oscillating background field. here, we present a high - level sketch of such an experiment, using superconducting cavities at $ \ sim $ ghz frequencies. we discuss the physical limits on signal power arising from cavity properties, and point out cavity geometries that could circumvent some of these limitations. we also consider how backgrounds, including vibrational noise and drive signal leakage, might impact sensitivity. while practical microwave field strengths are significantly below attainable static magnetic fields, the lack of geometric suppression, and higher quality factors, may allow superconducting cavity experiments to be competitive in some regimes.
|
arxiv:1912.11056
|
in this report we calculate the cross section and $ a _ { ll } $ asymmetry for the diffractive $ j / \ psi $ leptoproduction. we study dependences of the asymmetry on the structure of the pomeron - proton coupling
|
arxiv:hep-ph/9812330
|
it is well - known that in bulk, the solution of the bogoliubov - de gennes equations is the same whether or not the hartree - fock term is included. here the hartree - fock potential is position independent and, so, gives the same contribution to both the single - electron energies and the fermi level ( the chemical potential ). thus, the single - electron energies measured from the fermi level ( they control the solution ) stay the same. it is not the case for nanostructured superconductors, where quantum confinement breaks the translational symmetry and results in a position dependent hartree - fock potential. in this case its contribution to the single - electron energies depends on the relevant quantum numbers. we numerically solved the bogoliubov - de gennes equations with the hartree - fock term for a clean superconducting nanocylinder and found a shift of the curve representing the thickness - dependent oscillations of the critical superconducting temperature to larger diameters.
|
arxiv:0910.2352
|
by combining two independent approaches, inelastic neutron scattering measurements and density functional theory calculations, we study the spin - waves in the high - temperature collinear antiferromagnetic phase ( afm2 ) of mn $ _ 5 $ si $ _ 3 $. we obtain its magnetic ground - state properties and electronic structure. this study allowed us to determine the dominant magnetic exchange interactions and magnetocrystalline anisotropy in the afm2 phase of mn $ _ 5 $ si $ _ 3 $. moreover, the evolution of the spin excitation spectrum is investigated under the influence of an external magnetic field perpendicular to the anisotropy easy - axis. the low energy magnon modes show a different magnetic field dependence which is a direct consequence of their different precessional nature. finally, possible effects related to the dzyaloshinskii - moriya interaction are also considered.
|
arxiv:2011.05455
|
the presence of distribution shifts poses a significant challenge for deploying modern machine learning models in real - world applications. this work focuses on the target shift problem in a regression setting ( zhang et al., 2013 ; nguyen et al., 2016 ). more specifically, the target variable y ( also known as the response variable ), which is continuous, has different marginal distributions in the training source and testing domain, while the conditional distribution of features x given y remains the same. while most literature focuses on classification tasks with finite target space, the regression problem has an infinite dimensional target space, which makes many of the existing methods inapplicable. in this work, we show that the continuous target shift problem can be addressed by estimating the importance weight function from an ill - posed integral equation. we propose a nonparametric regularized approach named retasa to solve the ill - posed integral equation and provide theoretical justification for the estimated importance weight function. the effectiveness of the proposed method has been demonstrated with extensive numerical studies on synthetic and real - world datasets.
|
arxiv:2401.16410
|
results from lattice simulations.
|
arxiv:0809.1229
|
we build a simple model for feedback systems involving small rna ( srna ) molecules based on the iron metabolism system in the bacterium e. coli, and compare it with the corresponding system in h. pylori which uses purely transcriptional regulation. this reveals several unique features of srna based regulation that could be exploited by cells. firstly, we show that srna regulation can maintain a smaller turnover of target mrnas than transcriptional regulation, without sacrificing the speed of response to external shocks. secondly, we propose that a single srna can prioritize the usage of different target mrnas. this suggests that srna regulation would be more common in more complex systems which need to co - regulate many mrnas efficiently.
|
arxiv:q-bio/0611069
|
it is well - known that the noise associated with the collection of an astronomical image by a ccd camera is, in large part, poissonian. one would expect, therefore, that computational approaches that incorporate this a priori information will be more effective than those that do not. the richardson - lucy ( rl ) algorithm, for example, can be viewed as a maximum - likelihood ( ml ) method for image deblurring when the data noise is assumed to be poissonian. least - squares ( ls ) approaches, on the other hand, arises from the assumption that the noise is gaussian with fixed variance across pixels, which is rarely accurate. given this, it is surprising that in many cases results obtained using ls techniques are relatively insensitive to whether the noise is poissonian or gaussian. furthermore, in the presence of poisson noise, results obtained using ls techniques are often comparable with those obtained by the rl algorithm. we seek an explanation of these phenomena via an examination of the regularization properties of particular ls algorithms. in addition, a careful analysis of the rl algorithm yields an explanation as to why it is more effective than ls approaches for star - like objects, and why it provides similar reconstructions for extended objects. we finish with a convergence analysis of the rl algorithm. numerical results are presented throughout the paper. it is important to stress that the subject treated in this paper is not academic. in fact, in comparison with many ml algorithms, the ls algorithms are much easier to use and to implement, often provide faster convergence rates, and are much more flexible regarding the incorporation of constraints on the solution. consequently, if little to no improvement is gained in the use of an ml approach over an ls algorithm, the latter will often be the preferred approach.
|
arxiv:astro-ph/0409535
|
we determine all values of the parameters for which the cell modules form a standard system, for a class of cellular diagram algebras including partition, brauer, walled brauer, temperley - lieb and jones algebras. for this, we develop and apply a general theory of algebras with borelic pairs. the theory is also applied to give new uniform proofs of the cellular and quasi - hereditary properties of the diagram algebras and to construct quasi - hereditary 1 - covers, in the sense of rouquier, with exact borel subalgebras, in the sense of k \ " onig. another application of the theory leads to a proof that auslander - dlab - ringel algebras admit exact borel subalgebras.
|
arxiv:1607.01867
|
a recent argument of oerding shows that our calculation of the quantity delta, which determines the amplitude of the asymptotic decay of the particle density in d < 2 < 4, was in error. instead it is simply given by delta = n _ 0, the initial density, for uncorrelated initial conditions.
|
arxiv:cond-mat/9612070
|
rubalcaba and slater ( robert r. rubalcaba and peter j. slater. efficient ( j, k ) - domination. discuss. math. graph theory, 27 ( 3 ) : 409 - 423, 2007. ) define a $ ( j, k ) $ - dominating function on graph $ x $ as a function $ f : v ( x ) \ rightarrow \ { 0, \ ldots, j \ } $ so that for each $ v \ in v ( x ) $, $ f ( n [ v ] ) \ geq k $, where $ n [ v ] $ is the closed neighbourhood of $ v $. such a function is efficient if all of the vertex inequalities are met with equality. they give a simple necessary condition for efficient domination, namely : if $ x $ is an $ r $ - regular graph on $ n $ vertices that has an efficient $ ( 1, k ) $ - dominating function, then the size of the corresponding dominating set divides $ n \ cdot k $. the hamming graph $ h ( q, d ) $ is the graph on the vectors $ \ mathbb { z } _ q ^ d $ where two vectors are adjacent if and only if they are at hamming distance $ 1 $. we show that if $ q $ is prime, then the previous necessary condition is sufficient for $ h ( q, d ) $ to have an efficient $ ( 1, k ) $ - dominating function. this result extends a result of lee ( jaeun lee. independent perfect domination sets in cayley graphs. j. graph theory, 37 ( 4 ) : 213 - 219, 2001. ) on independent perfect domination in cayley graphs. we mention difficulties that arise for $ h ( q, d ) $ when $ q $ is a prime power but not prime.
|
arxiv:2107.09758
|
hierarchical clustering is a popular unsupervised data analysis method. for many real - world applications, we would like to exploit prior information about the data that imposes constraints on the clustering hierarchy, and is not captured by the set of features available to the algorithm. this gives rise to the problem of " hierarchical clustering with structural constraints ". structural constraints pose major challenges for bottom - up approaches like average / single linkage and even though they can be naturally incorporated into top - down divisive algorithms, no formal guarantees exist on the quality of their output. in this paper, we provide provable approximation guarantees for two simple top - down algorithms, using a recently introduced optimization viewpoint of hierarchical clustering with pairwise similarity information [ dasgupta, 2016 ]. we show how to find good solutions even in the presence of conflicting prior information, by formulating a constraint - based regularization of the objective. we further explore a variation of this objective for dissimilarity information [ cohen - addad et al., 2018 ] and improve upon current techniques. finally, we demonstrate our approach on a real dataset for the taxonomy application.
|
arxiv:1805.09476
|
reliable building energy audits are crucial for efficiency through heat loss detection. while drones assist inspections, they overlook the interplay between personality traits, stress management, and operational strategies expert engineers employ. this gap, combined with workforce shortages, necessitates effective knowledge transfer. this study proposes a vr - based training system for human - drone interaction in building heat loss inspection. participants piloted a virtual drone with a thermographic monitor to identify defects. by analyzing flight patterns, stress adaptation, and inspection performance across diverse trainees, we found : ( 1 ) flight trajectories - extraverts, intuitives, feelers, and perceivers explored larger areas but showed higher misclassification rates, while introverts, sensors, thinkers, and judgers demonstrated methodical approaches. ( 2 ) stress adaptation - heart rate variability revealed broader stress fluctuations among extraverts, intuitives, feelers, and perceivers, whereas introverts, sensors, thinkers, and judgers maintained steadier responses. task complexity magnified these differences. ( 3 ) inspection performance - extraverts, intuitives, and feelers achieved higher recall but over - identified defects. introverts, sensors, thinkers, and judgers made fewer random errors but risked overlooking subtle heat losses. these insights highlight the interplay among personality traits, stress management, and operational strategies in vr training for drone - assisted audits. the framework shows potential for addressing workforce shortages by facilitating knowledge transfer and optimizing human - drone collaboration.
|
arxiv:2504.03014
|
this note considers checking satisfiability of sets of propositional clauses ( sat instances ). it shows that " unipolar sets " of clauses ( containing no positive or no negative clauses ) provide an " early sign " of satisfiability of sat instances before all the clauses become satisfied in the course of solving sat problems. at this sign the processing can be terminated by " unipolar set termination ", ust thus before it is usually done by sat solvers ( table 1 ). an analysis of benchmark sat instances used at sat competitions shows that ust can speed up solving sat instances stemming from many real - world problems. the efficiency of ust increases with the " skewness " of the sat set being checked, that is the difference between probabilities of negated and unnegated literals in the set. many real - world problems, by virtue of their semantics, are skewed ( table 2 ). the efficiency of ust can be increased by revealing the " hidden skewness " of sat sets ( table 3 ).
|
arxiv:1612.05019
|
we study the generation of a secret key of maximum rate by a pair of terminals observing correlated sources and with the means to communicate over a noiseless public com - munication channel. our main result establishes a structural equivalence between the generation of a maximum rate secret key and the generation of a common randomness that renders the observations of the two terminals conditionally independent. the minimum rate of such common randomness, termed interactive common information, is related to wyner ' s notion of common information, and serves to characterize the minimum rate of interactive public communication required to generate an optimum rate secret key. this characterization yields a single - letter expression for the aforementioned communication rate when the number of rounds of interaction are bounded. an application of our results shows that interaction does not reduce this rate for binary symmetric sources. further, we provide an example for which interaction does reduce the minimum rate of communication. also, certain invariance properties of common information quantities are established that may be of independent interest.
|
arxiv:1304.2444
|
the mechanism of agcl - induced stress corrosion cracking of ti - 6246 was examined at \ si { 500 } { \ mega \ pascal } and \ si { 380 } { \ celsius } for \ si { 24 } { \ hour } exposures. sem and stem - edx examination of a fib - sectioned blister and crack showed that metallic ag was formed and migrated along the crack. tem analysis also revealed the presence of \ ce { sno2 } and \ ce { al2o3 } corrosion products mixed into \ ce { tio2 }. the fracture surface has a transgranular nature with a brittle appearance in the primary $ \ alpha $ phase. long, straight and non - interacting dislocations were observed in a cleavage - fractured primary $ \ alpha $ grain, with basal and pyramidal traces. this is consistent with a dislocation emission view of the the cracking mechanism.
|
arxiv:2010.13875
|
it is shown that every linear surjective isometry between two right, full, hilbert c * - modules is a sum of two maps : a ( bi - ) module map ( which is completely isometric and preserves the inner product ) and a map that reverses the ( bi - ) module actions. every such isometry can be extended to an isometry of the c * linking algebras.
|
arxiv:math/0104188
|
motivated by the proposed topological state in cu $ _ x $ bi $ _ 2 $ se $ _ 3 $, we study the possibility of phonon - mediated odd - parity superconductivity in spin - orbit coupled systems with time - reversal and inversion symmetry. for such systems, we show that, in general, pure electron - phonon coupling can never lead to a triplet state with a higher critical temperature than the leading singlet state. the coulomb pseudopotential, which is the repulsive part of the electron - electron interaction and is typically small in weakly correlated systems, is therefore critical to stabilizing the triplet state. we introduce a chirality quantum number, which identifies the electron - phonon vertex interactions that are most favorable to the triplet channel as those that conserve chirality. applying these results to cu $ _ x $ bi $ _ 2 $ se $ _ 3 $, we find that a phonon - mediated odd - parity state may be realized in the presence of weak electronic correlations if the chirality - preserving electron - phonon vertices are much stronger than the chirality - flipping vertices.
|
arxiv:1402.7061
|
large language models have significantly advanced the field of code generation, demonstrating the ability to produce functionally correct code snippets. however, advancements in generative ai for code overlook foundational software engineering ( se ) principles such as modularity, and single responsibility, and concepts such as cohesion and coupling which are critical for creating maintainable, scalable, and robust software systems. these concepts are missing in pipelines that start with pre - training and end with the evaluation using benchmarks. this vision paper argues for the integration of se knowledge into llms to enhance their capability to understand, analyze, and generate code and other se artifacts following established se knowledge. the aim is to propose a new direction where llms can move beyond mere functional accuracy to perform generative tasks that require adherence to se principles and best practices. in addition, given the interactive nature of these conversational models, we propose using bloom ' s taxonomy as a framework to assess the extent to which they internalize se knowledge. the proposed evaluation framework offers a sound and more comprehensive evaluation technique compared to existing approaches such as linear probing. software engineering native generative models will not only overcome the shortcomings present in current models but also pave the way for the next generation of generative models capable of handling real - world software engineering.
|
arxiv:2503.15282
|
we study a model of neutrino and dark matter within the framework of a minimal extended seesaw. this model is based on $ a _ 4 $ flavour symmetry along with the discrete $ z _ 3 \ times z _ 4 $ symmetry to stabilize the dark matter and construct desired mass matrices for neutrino mass. five - zero textures are imposed in the final $ 4 \ times4 $ active - sterile mass matrix, which significantly reduces free parameter in the model. three right - handed neutrinos were considered, two of them have nearly degenerate masses which help us to achieve baryogenesis via resonant leptogenesis. a singlet fermion ( sterile neutrino ) with mass $ \ sim \ mathcal { o } $ ( ev ) is also considered, and we are able to put bounds on active - sterile mixing parameters via neutrino oscillation data. resonant enhancement of lepton asymmetry is studied at tev scale, where we discuss a few aspects of baryogenesis considering the flavour effects. possibility of improvement in effective mass from $ 0 \ nu \ beta \ beta $ in the presence of a single generation of sterile neutrino flavour is also studied within the fermion sector. in the scalar sector, the imaginary component of the complex singlet scalar is behaving as a potential dark matter candidate and simultaneously the real part of the complex scalar is associated with the fermion sector for sterile mass generation. a broad region of dark matter mass is analyzed from various annihilation processes, and the vev of the complex scalar plays a pivotal role to achieve the observed relic density at the right ballpark.
|
arxiv:2010.13084
|
we show that the family of $ m $ - dimensional isotropic projections in $ \ r ^ { 2n } $ is transversal. as an application we show that the besicovitch - federer projection theorem holds for isotropic projections. we also use transversality to obtain almost sure estimates on the hausdorff dimension of isotropic projections of subsets $ e \ subset \ r ^ { 2n } $. these results may also be applied to gain information on the horizontal projections of the heisenberg group $ \ h ^ n $.
|
arxiv:1205.3010
|
using both analytic and numerical analyses of the poisson - nernst - planck equations we theoretically investigate the electric conductivity of a conical channel, which in accordance with recent experiments exhibits a strong non - linear pressure dependence. this mechanosensitive diodic behavior stems from the pressure - sensitive build - up or depletion of salt in the pore. from our analytic results we find that the optimal geometry for this diodic behavior strongly depends on the flow rate, the ideal ratio of tip - to - base - radii being equal to 0. 22 at zero flow. with increased flow this optimal ratio becomes smaller and simultaneously the diodic performance becomes weaker. consequently an optimal diode is obtained at zero - flow, which is realized by applying a pressure drop that is proportional to the applied potential and to the inverse square of the tip radius thereby countering electro - osmotic flow. when the applied pressure deviates from this ideal pressure drop the diodic performance falls sharply, explaining the dramatic mechanosensitivity observed in experiments.
|
arxiv:2205.02002
|
the modified arrott plots and kouvel $ { \ text - } $ fisher analysis are used to investigate the critical behavior of $ crte _ { 1 - x } sb _ { x } $ ferromagnetic material near its transition temperature $ t _ { c } $. the ferro $ { \ text - } $ paramagnetic transition is found to be a second $ { \ text - } $ order phase transition. for $ x = 0. 2 $, the critical exponents closely follow the mean field model with the estimated values of the exponents : $ \ beta $ = 0. 60 $ \ pm $ 0. 03, $ \ gamma $ = 1. 00 $ \ pm $ 0. 03 and $ \ delta $ = 2. 67 $ \ pm $ 0. 03. we also found with increasing sb $ { \ text - } $ concentrations, the critical exponents significantly deviate from the mean field values and gradually shift towards the 3 $ { \ text - } $ dimensional behavior. the deviation may indicate changes in the spin configuration with increasing sb concentrations.
|
arxiv:1809.05827
|
we present first results from a narrowband imaging program for intermediate redshift emission - line galaxies using the newly commissioned fourstar infrared camera at the 6. 5m magellan telescope. to enable prompt identification of h \ alpha \ emitters, a pair of custom 1 % filters, which sample low - airglow atmospheric windows at 1. 19 \ mu m and 2. 10 \ mu m, is used to detect both h \ alpha \ and [ oii ] \ lambda 3727 emission from the same redshift volume at z = 2. 2. initial observations are taken over a 130 arcmin ^ 2 area in the candels - cosmos field. the exquisite image quality resulting from the combination of the instrument, telescope, and standard site conditions ( ~ 0. 55 " fwhm ) allows the 1. 19 \ mu m and 2. 10 \ mu m data to probe 3 \ sigma \ emission - line depths down to 1. 0e - 17 erg / s / cm ^ 2 and 1. 2e - 17 erg / s / cm ^ 2 respectively, in less than 10 hours of integration time in each narrowband. for h \ alpha \ at z = 0. 8 and z = 2. 2, these fluxes correspond to observed star formation rates of ~ 0. 3 and ~ 4 msun / yr respectively. we find 122 sources with a 1. 19 \ mu m excess, and 136 with a 2. 10 \ mu m excess, 41 of which show an excess in both bands. the dual narrowband technique, as implemented here, is estimated to identify about > 80 % of z = 2. 2 h \ alpha \ emitters in the narrowband excess population. with the most secure such sample obtained to - date, we compute constraints on the faint - end slope of the z = 2. 2 h \ alpha \ luminosity function. these " narrow - deep " fourstar observations have been obtained as part of the larger newh \ alpha \ survey, which will combine the data with " wide - shallow " imaging through a similar narrowband filter pair with newfirm at the kpno / ctio 4m telescopes, to enable study of both luminous ( but rare ) and faint emission - line galaxies in the intermediate redshift universe. [ abridged ]
|
arxiv:1205.0017
|
we observed circinus x - 1 twice during a newly reached low - flux phase near zero orbital phase using the high - energy transmission grating spectrometer ( hetgs ) onboard chandra. in both observations the source did not show the p cygni lines we observed during the high - flux phases of the source in 2000 and 2001. during pre - zero phase the source did not exhibit significant variability and exhibited an emission - line spectrum rich in h - and he - like lines from high z elements such as si, s, ar, and ca. we analyzed all high resolution x - ray spectra by fitting photoionization and absorption models from the most recent version of the xstar code. the pre - zero phase spectrum could be fully modeled with a very hot photoionized plasma with an ionization parameter of log xi = 3. 0. post - zero phase episodes feature absorbers with variable high columns, ionization parameter, and luminosity. while cold absorption remains at levels quite similar to the one observed in previous years, the new observations show unprecedented levels of variable warm absorption. the line emissivities also indicate that the observed low source luminosity is inconsistent with a static hot accretion disk corona ( adc ), an effect that seems common to other near edge - on adc sources as well. we conclude that unless there exists some means of coronal heating other than x - rays, the true source luminosity is likely much higher and we observe obscuration in analogy to the extragalactic seyfert ii sources. we discuss possible consequences and relate cold, luke - warm, warm, and hot absorbers to dynamic accretion scenarios.
|
arxiv:0709.3336
|
we connect a broad class of generative models through their shared reliance on sequential decision making. motivated by this view, we develop extensions to an existing model, and then explore the idea further in the context of data imputation - - perhaps the simplest setting in which to investigate the relation between unconditional and conditional generative modelling. we formulate data imputation as an mdp and develop models capable of representing effective policies for it. we construct the models using neural networks and train them using a form of guided policy search. our models generate predictions through an iterative process of feedback and refinement. we show that this approach can learn effective policies for imputation problems of varying difficulty and across multiple datasets.
|
arxiv:1506.03504
|
let $ s $ be a smooth projective surface over $ \ mathbb { c } $. we study the local and global geometry of the nested hilbert scheme of points $ s ^ { [ n, n + 1, n + 2 ] } $. in particular, we show that $ s ^ { [ n, n + 1, n + 2 ] } $ is an irreducible local complete intersection with klt singularities. in addition, we compute the picard group of $ s ^ { [ n, n + 1, n + 2 ] } $ when $ h ^ 1 ( s, \ mathcal { o } _ s ) = 0 $. from the irreducibility of $ s ^ { [ n, n + 1, n + 2 ] } $, we deduce irreducibility for four other infinite families of nested hilbert schemes. we give the first explicit example of a reducible nested hilbert scheme, which allows us to show that $ s ^ { [ n _ 1, \ dots, n _ k ] } $ is reducible for $ k > 22 $.
|
arxiv:2106.06570
|
we study some observational signatures of nonlinearities of the electromagnetic field. first to all we show the vital role played by nonlinearities in triggering a material behavior of the vacuum with $ ( \ varepsilon > 0, \ mu < 0 ) $, which corresponds to a ferrimagnetic material. secondly, the permittivity and susceptibility induced by nonlinearities are considered in order to obtain the refractive index via the dispersion relation for logarithmic electrodynamics. finally, we consider the electromagnetic radiation produced by a moving charged particle interacting with a medium characterized by nonlinearities of the electromagnetic field. to this end we consider logarithmic electrodynamics. the result shows that the radiation is driven by the medium through which the particle travels like the one that happens in the cherenkov effect.
|
arxiv:2205.03252
|
we study systematically groups whose marked finite quotients form a recursive set. we give several definitions, and prove basic properties of this class of groups, and in particular emphasize the link between the growth of the depth function and solvability of the word problem. we give examples of infinitely presented groups whose finite quotients can be effectively enumerated. finally, our main result is that a residually finite group can be even not recursively presented and still have computable finite quotients, and that, on the other hand, it can have solvable word problem while still not having computable finite quotients.
|
arxiv:2002.02541
|
the paper demonstrates the use of variational autoencoders for graphical representation of a large database containing process - microstructure relationships. correlating microstructural features to processing is an essential first step to answer the difficult problem of process sequence design. in this paper, a large database of 346, 200 orientation distribution functions resulting from a variety of process sequences is constructed, where each sequence comprises up to four stages of tension, compression and rolling along different directions in various permutations. this opensource database is constructed for collaborative development of process design algorithms. the paper demonstrates a novel application of the large database : graphical representation of texture - process relationships. a variational autoencoder is used to reduce the entire database to a two dimensional latent space where variations in processes and properties can be visualized. using proximity analysis in this latent space, we can quickly unearth multiple process solutions to the problem of texture or property design.
|
arxiv:2001.09171
|
the rates of the $ x ( 3872 ) \ to \ pi ^ 0 \ pi ^ 0 \ chi _ { c1 } $ and $ x ( 3872 ) \ to \ pi ^ + \ pi ^ - \ chi _ { c1 } $ decays are estimated in the model of the triangle loop diagrams with charmed $ d ^ * \ bar dd $ and $ \ bar d ^ * d \ bar d $ mesons in the loops. there are the triangle logarithmic singularities in the physical region of the $ x ( 3872 ) \ to \ pi ^ 0 \ pi ^ 0 \ chi _ { c1 } $ decay which manifest themselves as narrow peaks in the $ \ pi ^ 0 \ chi _ { c1 } $ mass spectrum near the $ d ^ 0 \ bar d ^ 0 $ threshold. the model predicts approximately the same branching fractions of the $ x ( 3872 ) \ to \ pi ^ 0 \ pi ^ 0 \ chi _ { c1 } $ and $ x ( 3872 ) \ to \ pi ^ + \ pi ^ - \ chi _ { c1 } $ decays at the level of about ( 0. 8 - 1. 7 ) $ \ times10 ^ { - 4 } $. a distinct prediction of the model is the value of the ratio $ \ mathcal { r } = \ mathcal { b } ( x ( 3872 ) \ to \ pi ^ + \ pi ^ - \ chi _ { c1 } ) / \ mathcal { b } ( x ( 3872 ) \ to \ pi ^ 0 \ pi ^ 0 \ chi _ { c1 } ) \ approx1. 1 $. it weakly depends on the $ x ( 3872 ) $ resonance parameters and indicates a significant violation of the isotopic symmetry according to which one would expect $ \ mathcal { r } = 2 $.
|
arxiv:2405.09228
|
large - scale regression problems where both the number of variables, $ p $, and the number of observations, $ n $, may be large and in the order of millions or more, are becoming increasingly more common. typically the data are sparse : only a fraction of a percent of the entries in the design matrix are non - zero. nevertheless, often the only computationally feasible approach is to perform dimension reduction to obtain a new design matrix with far fewer columns and then work with this compressed data. $ b $ - bit min - wise hashing ( li and konig, 2011 ) is a promising dimension reduction scheme for sparse matrices which produces a set of random features such that regression on the resulting design matrix approximates a kernel regression with the resemblance kernel. in this work, we derive bounds on the prediction error of such regressions. for both linear and logistic models we show that the average prediction error vanishes asymptotically as long as $ q \ | \ beta ^ * \ | _ 2 ^ 2 / n \ rightarrow 0 $, where $ q $ is the average number of non - zero entries in each row of the design matrix and $ \ beta ^ * $ is the coefficient of the linear predictor. we also show that ordinary least squares or ridge regression applied to the reduced data can in fact allow us fit more flexible models. we obtain non - asymptotic prediction error bounds for interaction models and for models where an unknown row normalisation must be applied in order for the signal to be linear in the predictors.
|
arxiv:1308.1269
|
for a prime $ p $ and a rational elliptic curve $ e _ { / \ mathbb { q } } $, set $ k = \ mathbb { q } ( e [ p ] ) $ to denote the torsion field generated by $ e [ p ] : = \ operatorname { ker } \ { e \ xrightarrow { p } e \ } $. the class group $ \ operatorname { cl } _ k $ is a module over $ \ operatorname { gal } ( k / \ mathbb { q } ) $. given a fixed odd prime number $ p $, we study the average non - vanishing of certain galois stable quotients of the mod - $ p $ class group $ \ operatorname { cl } _ k / p \ operatorname { cl } _ k $. here, $ e $ varies over rational elliptic curves, ordered according to \ emph { height }. our results are conditional and rely on predictions made by delaunay and poonen - rains for the statistical variation of the $ p $ - primary parts of tate - shafarevich groups of elliptic curves. we also prove results in the case when the elliptic curve $ e _ { / \ mathbb { q } } $ is fixed and the prime $ p $ is allowed to vary.
|
arxiv:2204.09757
|
the frequency dependence of the raman coupling coefficient $ c ( \ omega ) $ is calculated numerically for square and cubic percolation clusters. no general scaling law in terms of the macroscopic parameters such as the fractal dimension $ d $ or the spectral dimension $ \ overline d $ is found. $ c ( \ omega ) $ is sensitive to the microscopic structure of the clusters and depends on : site - or bond - percolation, presence or absence of dangling bonds, scattering mechanism and polarization, presence or absence of polarizability disorder. this situation makes the derivation of macroscopic parameters from raman experiments unreliable.
|
arxiv:cond-mat/9210027
|
we study a recent model for calcium signal transduction. this model displays spiking, bursting and chaotic oscillations in accordance with experimental results. we calculate bifurcation diagrams and study the bursting behaviour in detail. this behaviour is classified according to the dynamics of separated slow and fast subsystems. it is shown to be of the fold - hopf type, a type which was previously only described in the context of neuronal systems, but not in the context of signal transduction in the cell.
|
arxiv:q-bio/0310018
|
the observed deficit of $ \ rm ^ 8b $ solar neutrinos may call for an improved standard model of the sun or an expanded standard model of particle physics ( { \ it e. g., } with neutrino masses and mixing ). in the former case, contemporary fluid motions and thermal fluctuations in the sun ' s core may modify nuclear reaction rates and restore agreement. to test this notion, we propose a search for short - - term variations of the solar neutrino flux.
|
arxiv:hep-ph/9208223
|
this work presents a fully binarized large language model ( fbi - llm ), demonstrating for the first time how to train a large - scale binary language model from scratch ( not the partial binary or ternary llm like bitnet b1. 58 ) to match the performance of its full - precision counterparts ( e. g., fp16 or bf16 ) in transformer - based llms. it achieves this by employing an autoregressive distillation ( ad ) loss with maintaining equivalent model dimensions ( 130m, 1. 3b, 7b ) and training data volume as regular llm pretraining, while delivering competitive results in terms of perplexity and task - specific effectiveness. intriguingly, by analyzing the training trajectory, we find that the pretrained weight is not necessary for training binarized llms from scratch. this research encourages a new computational framework and may facilitate the future design of specialized hardware tailored for fully 1 - bit llms. we make all models, code, and training dataset fully accessible and transparent to support further research ( code : https : / / github. com / liqunma / fbi - llm. model : https : / / huggingface. co / liqunma / ).
|
arxiv:2407.07093
|
we introduce litewebagent, an open - source suite for vlm - based web agent applications. our framework addresses a critical gap in the web agent ecosystem with a production - ready solution that combines minimal serverless backend configuration, intuitive user and browser interfaces, and extensible research capabilities in agent planning, memory, and tree search. for the core litewebagent agent framework, we implemented a simple yet effective baseline using recursive function calling, providing with decoupled action generation and action grounding. in addition, we integrate advanced research components such as agent planning, agent workflow memory, and tree search in a modular and extensible manner. we then integrate the litewebagent agent framework with frontend and backend as deployed systems in two formats : ( 1 ) a production vercel - based web application, which provides users with an agent - controlled remote browser, ( 2 ) a chrome extension leveraging litewebagent ' s api to control an existing chrome browser via cdp ( chrome devtools protocol ). the litewebagent framework is available at https : / / github. com / pathonai / litewebagent, with deployed frontend at https : / / lite - web - agent. vercel. app /.
|
arxiv:2503.02950
|
the majority of modern consumer - level energy is generated by real - time smart metering systems. these frequently contain anomalies, which prevent reliable estimates of the series ' evolution. this work introduces a hybrid modeling approach combining statistics and a convolutional autoencoder with a dynamic threshold. the threshold is determined based on mahalanobis distance and moving averages. it has been tested using real - life energy consumption data collected from smart metering systems. the solution includes a real - time, meter - level anomaly detection system that connects to an advanced monitoring system. this makes a substantial contribution by detecting unusual data movements and delivering an early warning. early detection and subsequent troubleshooting can financially benefit organizations and consumers and prevent disasters from occurring.
|
arxiv:2404.04311
|
we study synchronization dynamics in binary mixtures of locally coupled kuramoto oscillators which perform brownian motion in a two - dimensional box. we introduce two models, where in model $ \ cal i $ there are two type of oscillators, say $ \ cal a $ and $ \ cal b $, and any two similar oscillators tend to synchronize their phases, while any two dissimilar ones tend to be out of phase. in model $ \ cal j $, in contrast, the oscillators in subpopulation $ \ cal a $ behave as in model $ \ cal i $, while the oscillators in subpopulation $ \ cal b $ tend to be out of phase with all the others. in the real space all the oscillators in both models interact via a soft - core repulsive potential. both subpopulations of model $ \ cal i $ and subpopulation $ \ cal a $ of model $ \ cal j $, by their own, exhibit a phase coherent attractor in a certain region of model parameters. the approach to the attractor, after an initial transient regime, is exponential with some characteristic synchronization time scale $ \ tau $. numerical analysis reveals that the attractors of the two subpopulations survive within model $ \ cal i $, regardless of the composition of the mixture $ \ phi $ and the strength of the cross - population negative coupling constant $ h $, and that $ \ tau $ sensitively depends on $ \ phi $, $ h $ and the packing fraction. in particular, the ability of the oscillators to move and exchange neighbours can significantly decrease $ \ tau $. in contrast, model $ \ cal j $ predicts suppression of the synchronized state in subpopulation $ \ cal a $ and emergence of the coherent attractor in the " contrarians " subpopulation $ \ cal b $ for strong and weak cross - population coupling, respectively.
|
arxiv:2102.12441
|
we show that the neumann problem for laplace ' s equation in a convex domain $ \ omega $ with boundary data in $ l ^ p ( \ partial \ omega ) $ is uniquely solvable for $ 1 < p < \ infty $. as a consequence, we obtain the helmholtz decomposition of vector fields in $ l ^ p ( \ omega, \ mathbb { r } ^ d ) $.
|
arxiv:1001.0778
|
although the notion of crossed groups was originally introduced only in the simplicial case, the definition makes sense in the other categories. for instance, batanin and markl studied crossed interval groups to investigate symmetries on the hochschild cohomology in view of operads. the aim of this paper is to make a comprehensive understanding of crossed groups for arbitrary base categories. in particular, we focus on the local presentability of the category of crossed groups, monadicity, and the basechange theorem along certain sorts of functors. the paper also contains the classification of crossed interval groups, which batanin and markl concerned about.
|
arxiv:1802.06644
|
about 4. 4 million hadronic decays of z bosons, recorded by the opal detector at lep at a centre - of - mass energy of around sqrt ( s ) = 91. 2 gev, are used to determine the mean charged particle multiplicities for the three light quark flavours. events from primary u, d, and s quarks are tagged by selecting characteristic particles which carry a large fraction of the beam energy. the charged particle multiplicities are measured in the hemispheres opposite to these particles. an unfolding procedure is applied to obtain these multiplicities for each primary light quark flavour. this yields < n _ u > = 17. 77 + - 0. 51 + 0. 86 - 1. 20, < n _ d > = 21. 44 + - 0. 63 + 1. 46 - 1. 17, < n _ s > = 20. 02 + - 0. 13 + 0. 39 - 0. 37, where statistical and systematic errors are given. the results for < n _ u > and < n _ d > are almost fully statistically anti - correlated. within the errors the result is consistent with the flavour independence of the strong interaction for the particle multiplicities in events from the light up, down, and strange quarks.
|
arxiv:hep-ex/0011022
|
in this work, we evaluate various existing dialogue relevance metrics, find strong dependency on the dataset, often with poor correlation with human scores of relevance, and propose modifications to reduce data requirements and domain sensitivity while improving correlation. our proposed metric achieves state - of - the - art performance on the humod dataset while reducing measured sensitivity to dataset by 37 % - 66 %. we achieve this without fine - tuning a pretrained language model, and using only 3, 750 unannotated human dialogues and a single negative example. despite these limitations, we demonstrate competitive performance on four datasets from different domains. our code, including our metric and experiments, is open sourced.
|
arxiv:2206.01823
|
unsupervised semantic segmentation is a challenging task that segments images into semantic groups without manual annotation. prior works have primarily focused on leveraging prior knowledge of semantic consistency or priori concepts from self - supervised learning methods, which often overlook the coherence property of image segments. in this paper, we demonstrate that the smoothness prior, asserting that close features in a metric space share the same semantics, can significantly simplify segmentation by casting unsupervised semantic segmentation as an energy minimization problem. under this paradigm, we propose a novel approach called smooseg that harnesses self - supervised learning methods to model the closeness relationships among observations as smoothness signals. to effectively discover coherent semantic segments, we introduce a novel smoothness loss that promotes piecewise smoothness within segments while preserving discontinuities across different segments. additionally, to further enhance segmentation quality, we design an asymmetric teacher - student style predictor that generates smoothly updated pseudo labels, facilitating an optimal fit between observations and labeling outputs. thanks to the rich supervision cues of the smoothness prior, our smooseg significantly outperforms stego in terms of pixel accuracy on three datasets : cocostuff ( + 14. 9 % ), cityscapes ( + 13. 0 % ), and potsdam - 3 ( + 5. 7 % ).
|
arxiv:2310.17874
|
we discuss the renormalization induced by interactions of a two - dimensional truncated fermi surface ( fs ) model. using a field theoretical renormalization group method we calculate the critical renormalized physical chemical potential. we show that it either vanishes or approaches a non - zero value. we argue that the vanishing of the chemical potential is indicative of a further truncation of the fs we started with and might well represent an insulating spin liquid phase.
|
arxiv:cond-mat/0203376
|
we report about a short flare from the blazar nrao 530 occurred on 17 february 2004 and detected serendipitously by the ibis / isgri detector on board integral. in the 20 - 40 kev energy range, the source, that is otherwise below the detection limit, is detected at a level of ~ 2 x 10 ^ - 10 erg cm ^ - 2 s ^ - 1 during a time interval of less than 2000 s, which is about a factor 2 above the detection threshold. at other wavelengths, only nearly - simultaneous radio data are available ( 1 observation at 2 cm on 11 february 2004 ), indicating a moderate increase of the polarization. this appears to be the shortest time variability episode ever detected in a high luminosity blazar at hard x - rays, unless the blazar is contaminated by the presence of an unknown unresolved rapidly varying source.
|
arxiv:astro-ph/0601101
|
we have conducted a vla search for radio pulsars at the positions of 44 nearby ob runaway stars. the observations involved both searching images for point sources of continuum emission and a time series analysis. our mean flux sensitivity to pulsars slower than 50 ms was 0. 2 mjy. no new pulsars were found in the survey. the size of the survey, combined with the high sensitivity of the observations, sets a significant constraint on the probability, $ f _ p $, of a runaway ob star having an observable pulsar companion. we find $ f _ p \ le 6. 5 $ \ % with 95 \ % confidence, if the general pulsar luminosity function is applicable to ob star pulsar companions. if a pulsar beaming fraction of \ onethird \ is assumed, then we estimate that fewer than 20 \ % of runaway ob stars have neutron star companions, unless pulsed radio emission is frequently obscured by the ob stellar wind. our result is consistent with the dynamical ( or cluster ) ejection model for the formation of ob runaways. the supernova ejection model is not ruled out, but is constrained by these observations to allow only a small binary survival fraction, which may be accommodated if neutron stars acquire significant natal kicks. according to leonard, hills and dewey ( 1994 ), a 20 \ % survival fraction corresponds to a 3 - d kick velocity of 420 km s $ ^ { - 1 } $. this value is in close agreement with recent revisions of the pulsar velocity distribution.
|
arxiv:astro-ph/9509087
|
interferometric observables are strongly correlated, yet it is common practice to ignore these correlations in the data analysis process. we develop an empirical model for the correlations present in very large telescope interferometer gravity data and show that properly accounting for them yields fainter detection limits and increases the reliability of potential detections. we extracted the correlations of the ( squared ) visibility amplitudes and the closure phases directly from intermediate products of the gravity data reduction pipeline and fitted our empirical models to them. then, we performed model fitting and companion injection and recovery tests with both simulated and real gravity data, which are affected by correlated noise, and compared the results when ignoring the correlations and when properly accounting for them with our empirical models. when accounting for the correlations, the faint source detection limits improve by a factor of up to $ \ sim 2 $ at angular separations $ > 20 ~ \ rm { mas } $. for commonly used detection criteria based on $ \ chi ^ 2 $ statistics, this mostly results in claimed detections being more reliable. ignoring the correlations present in interferometric data is a dangerous assumption which might lead to a large number of false detections. the commonly used detection criteria ( e. g. in the model fitting pipeline candid ) are only reliable when properly accounting for the correlations ; furthermore, instrument teams should work on providing full covariance matrices instead of statistically independent error bars as part of the official data reduction pipelines.
|
arxiv:2011.01209
|
collisional growth of dust occurs in all regions of protoplanetary disks with certain materials dominating between various condensation lines. the sticking properties of the prevalent dust species depend on the specific temperatures. the inner disk is the realm of silicates spanning a wide range of temperatures from room temperature up to sublimation beyond $ 1500 \, \ mathrm { k } $. for the first time, we carried out laboratory collision experiments with hot levitated basalt dust aggregates of $ 1 \, \ rm mm $ in size. the aggregates are compact with a filling factor of $ 0. 37 \ pm 0. 06 $. the constituent grains have a wide size distribution that peaks at about $ 0. 6 \, \ mu \ mathrm { m } $. temperatures in the experiments are varied between approximately $ 600 \, \ mathrm { k } $ and $ 1100 \, \ mathrm { k } $. collisions are slow with velocities between $ 0. 002 \, \ mathrm { m } \, \ mathrm { s } ^ { - 1 } $ and $ 0. 15 \, \ mathrm { m } \, \ mathrm { s } ^ { - 1 } $, i. e., relevant for protoplanetary disks. aside from variations of the coefficients of restitution due to varying collision velocities, the experiments show low sticking probability below $ 900 \, \ mathrm { k } $ and an increasing sticking probability starting at $ 900 \, \ mathrm { k } $. this implies that dust can grow to larger size in hot regions, which might change planet formation. one scenario is an enhanced probability for local planetesimal formation. another scenario is a reduction of planetesimal formation as larger grains are more readily removed as a consequence of radial drift. however, the increased growth at high temperatures likely changes planetesimal formation one way or the other.
|
arxiv:1908.11657
|
we study the singular limit of a rotating compressible fluid described by a scaled barotropic navier - stokes system, where the rossby number, the mach number and the froude number tend to 0 in a particular mutual rate while the reynolds number tends to infinity. the inviscid planar euler system is identified as the limit problem. the proof is based on the application of the method of relative entropies and careful analysis of oscillatory integrals describing the propagation of rossby - acoustic waves.
|
arxiv:1303.3998
|
the effects of fluid viscosity on the kinematics of a small swimmer at low reynolds number are investigated in both experiments and in a simple model. the swimmer is the nematode caenorhabditis elegans, which is an undulating roundworm approximately 1 mm long. experiments show that the nematode maintains a highly periodic swimming behavior as the fluid viscosity is varied from 1. 0 mpa - s to 12 mpa - s. surprisingly, the nematode ' s swimming speed ( ~ 0. 35 mm / s ) is nearly insensitive to the range of fluid viscosities investigated here. however, the nematode ' s beating frequency decreases to an asymptotic value ( ~ 1. 7 hz ) with increasing fluid viscosity. a simple model is used to estimate the nematode ' s young ' s modulus and tissue viscosity. both material properties increase with increasing fluid viscosity. it is proposed that the increase in young ' s modulus may be associated with muscle contraction in response to larger mechanical loading while the increase in effective tissue viscosity may be associated with the energy necessary to overcome increased fluid drag forces.
|
arxiv:0912.3402
|
let $ \ widehat { \ mathcal { s } } _ g ^ { \ alpha, \ beta } ( \ mathbb { b } ^ n ) $ be a subclass of normalized biholomorphic mappings defined on the unit ball in $ \ mathbb { c } ^ n, $ which is closely related to the starlike mappings. firstly, we obtain the growth theorem for $ \ widehat { \ mathcal { s } } _ g ^ { \ alpha, \ beta } ( \ mathbb { b } ^ n ) $. secondly, we apply the growth theorem and a new type of the boundary schwarz lemma to establish the distortion theorems of the fr \ ' { e } chet - derivative type and the jacobi - determinant type for this subclass, and the distortion theorems with $ g $ - starlike mapping ( resp. starlike mapping ) are partly established also. at last, we study the kirwan and pell type results for the compact set of mappings which have $ g $ - parametric representation associated with a modified roper - suffridge extension operator, which extend some earlier related results.
|
arxiv:1910.09150
|
accurate tracking of the internal electrochemical states of lithium - ion battery during cycling enables advanced battery management systems to operate the battery safely and maintain high performance while minimizing battery degradation. to this end, techniques based on voltage measurement have shown promise for estimating the lithium surface concentration of active material particles, which is an important state for avoiding aging mechanisms such as lithium plating. however, methods relying on voltage often lead to large estimation errors when the model parameters change during aging. in this paper, we utilize the in - situ measurement of the battery expansion to augment the voltage and develop an observer to estimate the lithium surface concentration distribution in each electrode particle. we demonstrate that the addition of the expansion signal enables us to correct the negative electrode concentration states in addition to the positive electrode. as a result, compared to a voltage only observer, the proposed observer can successfully recover the surface concentration when the electrodes ' stoichiometric window changes, which is a common occurrence under aging by loss of lithium inventory. with a 5 % shift in the electrodes ' stoichiometric window, the results indicate a reduction in state estimation error for the negative electrode surface concentration. under this simulated aged condition, the voltage based observer had 9. 3 % error as compared to the proposed voltage and expansion observer which had 0. 1 % error in negative electrode surface concentration.
|
arxiv:2009.14270
|
a new compton longitudinal polarimeter currently under construction for hera is presented. the key component of the polarimeter is a fabry - perot cavity located around the electron beam pipe. with such an optical cavity, a continuous laser power equivalent to 5 kw, much higher than those commercially available, can be achieved, leading to one backscattered photon per bunch crossing. this ` ` few - photon mode ' ' will allow a very precise determination of the calorimeter response with little systematic uncertainty. the electron polarization measurement at the per mill level is expected.
|
arxiv:hep-ex/0201033
|
with the advancement and proliferation of technology, non - profit organisations have embraced social media platforms to improve their operational capabilities through brand advocacy, among many other strategies. the effect of such social media campaigns on these institutions, however, remains largely underexplored, especially during disaster periods. this work introduces and applies a quantitative investigative framework to understand how social media influence the behaviour of donors and their usage of these platforms throughout ( natural ) disasters. more specifically, we explore how on - line engagement - - as captured by facebook interactions and google search trends - - corresponds to the donors ' behaviour during the catastrophic 2019 - - 2020 australian bushfire season. to discover this relationship, we analyse the record of donations made to the australian red cross throughout this period. our exploratory study reveals that social media campaigns are effective in encouraging on - line donations made via a dedicated website. we also compare this mode of giving to more regular, direct deposit gifting.
|
arxiv:2210.09034
|
automation of brain tumor segmentation in 3d magnetic resonance images ( mris ) is key to assess the diagnostic and treatment of the disease. in recent years, convolutional neural networks ( cnns ) have shown improved results in the task. however, high memory consumption is still a problem in 3d - cnns. moreover, most methods do not include uncertainty information, which is especially critical in medical diagnosis. this work studies 3d encoder - decoder architectures trained with patch - based techniques to reduce memory consumption and decrease the effect of unbalanced data. the different trained models are then used to create an ensemble that leverages the properties of each model, thus increasing the performance. we also introduce voxel - wise uncertainty information, both epistemic and aleatoric using test - time dropout ( ttd ) and data - augmentation ( tta ) respectively. in addition, a hybrid approach is proposed that helps increase the accuracy of the segmentation. the model and uncertainty estimation measurements proposed in this work have been used in the brats ' 20 challenge for task 1 and 3 regarding tumor segmentation and uncertainty estimation.
|
arxiv:2012.15294
|
proof of work ( pow ) is a sybil - deterrence security mechanism. it introduces an external cost to a system by requiring computational effort to perform actions. however, since its inception, a central challenge was to tune this cost. initial designs for deterring spam email and dos attacks applied overhead equally to honest participants and attackers. requiring too little effort did not deter attacks, whereas too much encumbered honest participation. this might be the reason it was never widely adopted. nakamoto overcame this trade - off in bitcoin by distinguishing desired from malicious behavior and introducing internal rewards for the former. this solution gained popularity in securing cryptocurrencies and using the virtual internally - minted tokens for rewards. however, in existing blockchain protocols the internal rewards fund ( almost ) the same value of external expenses. thus, as the token value soars, so does the pow expenditure. bitcoin pow, for example, already expends as much electricity as colombia or switzerland. this amount of resource - guzzling is unsustainable and hinders even wider adoption of these systems. in this work we present hybrid expenditure blockchain ( heb ), a novel pow mechanism. heb is a generalization of nakamoto ' s protocol that enables tuning the external expenditure by introducing a complementary internal - expenditure mechanism. thus, for the first time, heb decouples external expenditure from the reward value. we show a practical parameter choice by which heb requires significantly less external consumption compare to nakamoto ' s protocol, its resilience against rational attackers is similar, and it retains the decentralized and permissionless nature of the system. taking the bitcoin ecosystem as an example, heb cuts the electricity consumption by half.
|
arxiv:1911.04124
|
the protein folding problem is stated and a list of properties that do not depend upon specific molecules is compiled and analyzed. the relationship of this analysis to future simulations is emphasized. the choice of power and time as variables as opposed to energy and time is discussed. a wave motion model is reviewed and related to the action in classical mechanics. it is argued that the properties of the action support the idea that folding takes place in small steps. it is explained how catastrophe theory has been employed in wave motion models and how it can be used in examination of successful simulations
|
arxiv:1709.07953
|
this paper considers the problem of channel coding over gaussian intersymbol interference ( isi ) channels with a given metric decoding rule. specifically, it is assumed that the mismatched decoder has an incorrect assumption on the impulse response function. the mismatch capacity is the highest achievable rate for a given decoding rule. existing lower bounds to the mismatch capacity for channels and decoding metrics with memory ( as in our model ) are presented only in the form of multi - letter expressions that have not been calculated in practice. consequently, they provide little insight on the mismatch problem. in this paper, we derive computable single - letter lower bounds to the mismatch capacity, and discuss some implications of our results. our achievable rates are based on two ensembles, the ensemble of codewords generated by an autoregressive process, and the ensemble of codewords drawn uniformly over a " type class " of real - valued sequences. computation of our achievable rates demonstrates non - trivial behavior of the achievable rates as a function of the mismatched parameters. as a simple application of our technique, we derive also the random coding exponent associated with a mismatched decoder which assumes that there is no isi at all. finally, we compare our results with universal decoders which are designed outside the true class of channels that we consider in this paper.
|
arxiv:1706.05883
|
transport makes an impact across sdgs, encompassing climate change, health, inequality and sustainability. it is also an area in which individuals are able to make decisions which have potential to collectively contribute to significant and wide - ranging benefits. governments and authorities need citizens to make changes towards adopting sustainable transport behaviours and behaviour change interventions are being used as tools to foster changes in travel choices, towards more sustainable modes. blockchain technology has the potential to bring new levels of scale to transport behaviour change interventions, but a rigorous approach to token design is required. this paper uses a survey of research projects and use cases to analyse current applications of blockchain technology in transport behaviour change interventions, and identifies barriers and limitations to achieving targeted change at scale. the paper draws upon these findings to outline a research agenda that brings a focus on correlating specific behaviour change techniques ( bcts ) to token design, and defines processes for standardising token designs in behaviour change tools. the paper further outlines architecture and operational considerations for blockchain - based platforms in behaviour change interventions, such that design choices do not compromise opportunities or wider environmental goals.
|
arxiv:2104.01852
|
model compression is important in federated learning ( fl ) with large models to reduce communication cost. prior works have been focusing on sparsification based compression that could desparately affect the global model accuracy. in this work, we propose a new scheme for upstream communication where instead of transmitting the model update, each client learns and transmits a light - weight synthetic dataset such that using it as the training data, the model performs similarly well on the real training data. the server will recover the local model update via the synthetic data and apply standard aggregation. we then provide a new algorithm fedsynth to learn the synthetic data locally. empirically, we find our method is comparable / better than random masking baselines in all three common federated learning benchmark datasets.
|
arxiv:2204.01273
|
a family of the pair hopping models exhibiting the incompressible quantum liquid at fractional filling $ 1 / m ^ d $ is constructed in $ d $ dimensional lattice. except in one dimension, the lattice is the generalized edge - shared triangular lattice, for example the triangular lattice in two dimensions and tetrahedral lattice in three dimensions. they obey the new symmetry, conservation of the center - of - mass position proposed by seidel et al.. \ cite { seidel2005 } the uniqueness of the ground state is proved rigorously in the open boundary condition. the finiteness of the excitation energy is calculated by the single mode approximation.
|
arxiv:0912.1908
|
this paper presents a novel extension of the $ \ { 1, 2, 3, 1 ^ { k } \ } $ - inverse concept to complex rectangular matrices, denoted as a $ w $ - weighted $ \ { 1, 2, 3, 1 ^ { k } \ } $ - inverse ( or $ \ { 1 ', 2 ', 3 ', { 1 ^ { k } } ' \ } $ - inverse ), where the weight $ w \ in \ mathbb { c } ^ { n \ times m } $. the study begins by introducing a weighted $ \ { 1, 2, 3 \ } $ - inverse ( or $ \ { 1 ', 2 ', 3 ' \ } $ - inverse ) along with its representations and characterizations. the paper establishes criteria for the existence of $ \ { 1 ', 2 ', 3 ' \ } $ - inverses and extends the criteria to $ \ { 1 ' \ } $ - inverses. it is further demonstrated that $ a \ in \ mathbb { c } ^ { m \ times n } $ admits a $ \ { 1 ', 2 ', 3 ', { 1 ^ { k } } ' \ } $ - inverse if and only if $ r ( waw ) = r ( a ) $, where $ r ( \ cdot ) $ is the rank of a matrix. the work additionally establishes various representations for the set $ a \ { 1 ', 2 ', 3 ', { 1 ^ { k } } ' \ } $, including canonical representations derived through singular value and core - nilpotent decompositions. this, in turn, yields distinctive canonical representations for the set $ a \ { 1, 2, 3, { 1 ^ { k } } \ } $. $ \ { 1 ', 2 ', 3 ', { 1 ^ { k } } ' \ } $ - inverse is shown to be unique if and only if it has index $ 0 $ or $ 1 $, reducing it to the weighted core inverse. moreover, the paper investigates properties and characterizations of $ \ { 1 ', 2 ', 3 ', { 1 ^ { k } } ' \ } $ - inverses, which then results in new insights into the characterizations of the set $ a \ { 1, 2, 3, { 1 ^ { k } } \ } $.
|
arxiv:2312.01370
|
the construction and application of knowledge graphs have seen a rapid increase across many disciplines in recent years. additionally, the problem of uncovering relationships between developments in the covid - 19 pandemic and social media behavior is of great interest to researchers hoping to curb the spread of the disease. in this paper we present a knowledge graph constructed from covid - 19 related tweets in the los angeles area, supplemented with federal and state policy announcements and disease spread statistics. by incorporating dates, topics, and events as entities, we construct a knowledge graph that describes the connections between these useful information. we use natural language processing and change point analysis to extract tweet - topic, tweet - date, and event - date relations. further analysis on the constructed knowledge graph provides insight into how tweets reflect public sentiments towards covid - 19 related topics and how changes in these sentiments correlate with real - world events.
|
arxiv:2110.04932
|
vector quantized diffusion ( vq - diffusion ) is a powerful generative model for text - to - image synthesis, but sometimes can still generate low - quality samples or weakly correlated images with text input. we find these issues are mainly due to the flawed sampling strategy. in this paper, we propose two important techniques to further improve the sample quality of vq - diffusion. 1 ) we explore classifier - free guidance sampling for discrete denoising diffusion model and propose a more general and effective implementation of classifier - free guidance. 2 ) we present a high - quality inference strategy to alleviate the joint distribution issue in vq - diffusion. finally, we conduct experiments on various datasets to validate their effectiveness and show that the improved vq - diffusion suppresses the vanilla version by large margins. we achieve an 8. 44 fid score on mscoco, surpassing vq - diffusion by 5. 42 fid score. when trained on imagenet, we dramatically improve the fid score from 11. 89 to 4. 83, demonstrating the superiority of our proposed techniques.
|
arxiv:2205.16007
|
a common perception assumes that magnetic memories require ferromagnetic materials with a non - zero net magnetic moment. however, it has been recently proposed that compensated antiferromagnets with a zero net moment may represent a viable alternative to ferromagnets. so far, experimental research has focused on bistable memories in antiferromagnetic metals. in the present work we demonstrate a multiple - stable memory device in epitaxial manganese telluride ( mnte ) which is an antiferromagnetic counterpart of common ii - vi semiconductors. favorable micromagnetic characteristics of mnte allow us to demonstrate a smoothly varying antiferromagnetic anisotropic magnetoresistance ( amr ) with a harmonic angular dependence on the applied magnetic field, analogous to ferromagnets. the continuously varying amr provides means for the electrical read - out of multiple - stable antiferromagnetic memory states which we set by heat - assisted magneto - recording and by changing the angle of the writing field. we explore the dependence of the magnitude of the zero - field read - out signal on the strength of the writing field and demonstrate the robustness of the antiferromagnetic memory states against strong magnetic field perturbations. we ascribe the multiple - stability in our antiferromagnetic memory to different distributions of domains with the n \ ' eel vector aligned along one of the three $ c $ - plane magnetic easy axes in the hexagonal mnte film. the domain redistribution is controlled during the heat - assisted recording by the strength and angle of the writing field and freezes when sufficiently below the n \ ' eel temperature.
|
arxiv:1508.04877
|
cross sections and polarization transfer observables in the $ ^ { 16 } $ o $ ( p, p ' ) $ reactions at 392 mev were measured at several angles between $ \ theta _ { lab } = $ 0 $ ^ \ circ $ and 14 $ ^ \ circ $. the non - spin - flip ( $ { \ delta } s = 0 $ ) and spin - flip ( $ { \ delta } s = 1 $ ) strengths in transitions to several discrete states and broad resonances in $ ^ { 16 } $ o were extracted using a model - independent method. the giant resonances in the energy region of $ e _ x = 19 - $ 27 mev were found to be predominantly excited by $ { \ delta } l = 1 $ transitions. the strength distribution of spin - dipole transitions with $ { \ delta } s = 1 $ and $ { \ delta } l = 1 $ were deduced. the obtained distribution was compared with a recent shell model calculation. experimental results are reasonably explained by distorted - wave impulse approximation calculations with the shell model wave functions.
|
arxiv:nucl-ex/0202015
|
we review the timing and spectral evolution of black hole x - ray binary systems, with emphasis on the current accretion - ejection paradigm. when in outburst, stellar mass black hole binaries may become the brightest x - ray sources in the sky. analysis of high signal to noise data has resulted in a general framework of correlated x - ray spectral and fast timing behavior during an outburst. we utilize recent data from small but powerful observatories launched in the last decade supported by multi - wavelength ground - based observations. coordinated observations showed that outflows ( in the form of jets and winds ) are an integral part of this evolution, providing a coherent phenomenological picture that we discuss in terms of the hardness - intensity diagram and spectral states. we pay particular attention to the evolution of broad and narrow emission and absorption lines and hard tails in the energy spectrum, quasi - periodic oscillations, lags and reverberation from fast timing studies, making the connections with multi - wavelength observations when relevant. we use the bright outburst of maxi j1820 + 070 as a recent test case to discuss different aspects of spectral and timing evolution, but the data and results are not limited to this source. in the second part of the review, we discuss competing theoretical models that can explain different aspects of the rich phenomenology. data from future missions and simulation results will have the power to resolve discrepancies in these models and black hole binary research will continue to be an exciting field that allows for tests of fundamental physics and studies of the properties of matter in strong gravitational fields.
|
arxiv:2206.14410
|
quantum metrology makes use of coherent superpositions to detect weak signals. while in principle the sensitivity can be improved by increasing the density of sensing particles, in practice this improvement is severely hindered by interactions between them. using a dense ensemble of interacting electronic spins in diamond, we demonstrate a novel approach to quantum metrology. it is based on a new method of robust quantum control, which allows us to simultaneously eliminate the undesired effects associated with spin - spin interactions, disorder and control imperfections, enabling a five - fold enhancement in coherence time compared to conventional control sequences. combined with optimal initialization and readout protocols, this allows us to break the limit for ac magnetic field sensing imposed by interactions, opening a promising avenue for the development of solid - state ensemble magnetometers with unprecedented sensitivity.
|
arxiv:1907.10066
|
test resources are usually limited and therefore it is often not possible to completely test an application before a release. therefore, testers need to focus their activities on the relevant code regions. in this paper, we introduce an inverse defect prediction approach to identify methods that contain hardly any faults. we applied our approach to six java open - source projects and show that on average 31. 6 % of the methods of a project have a low fault risk ; they contain in total, on average, only 5. 8 % of all faults. furthermore, the results suggest that, unlike defect prediction, our approach can also be applied in cross - project prediction scenarios. therefore, inverse defect prediction can help prioritize untested code areas and guide testers to increase the fault detection probability.
|
arxiv:1805.01132
|
the purpose of this work is to study the change in the structure of the ge - se network upon doping with ag. the total structure factor s ( q ) for two samples has been measured by neutron diffraction using the two - axis diffractometer dedicated to structural studies of amorphous materials, d4, at the institut laue langevin. we have derived the corresponding radial distribution functions for each sample and each temperature, which gives us an insight about the composition and temperature dependence of the correlation distances and coordination numbers in the short - range. our results are compatible with the presence of both gese4 / 2 tetrahedra and se - se bonds. the ag atoms are linked to se in a triangular environment. numerical simulations allowing the identification of the main peaks in the total pair correlation functions have complemented the neutron diffraction measurements.
|
arxiv:0801.0868
|
in geostatistics, and also in other applications in science and engineering, we are now performing updates on gaussian process models with many thousands or even millions of components. these large - scale inferences involve computational challenges, because the updating equations cannot be solved as written, owing to the size and cost of the matrix operations. they also involve representational challenges, to account for judgements of heterogeneity concerning the underlying fields, and diverse sources of observations. diagnostics are particularly valuable in this situation. we present a diagnostic and visualisation tool for large - scale gaussian updates, the ` medal plot '. this shows the updated uncertainty for each observation, and also summarises the sharing of information across observations, as a proxy for the sharing of information across the state vector. it allows us to ` sanity - check ' the code implementing the update, but it can also reveal unexpected features in our modelling. we discuss computational issues for large - scale updates, and we illustrate with an application to assess mass trends in the antarctic ice sheet.
|
arxiv:1406.5005
|
sampling - based motion planning under task constraints is challenging because the null - measure constraint manifold in the configuration space makes rejection sampling extremely inefficient, if not impossible. this paper presents a learning - based sampling strategy for constrained motion planning problems. we investigate the use of two well - known deep generative models, the conditional variational autoencoder ( cvae ) and the conditional generative adversarial net ( cgan ), to generate constraint - satisfying sample configurations. instead of precomputed graphs, we use generative models conditioned on constraint parameters for approximating the constraint manifold. this approach allows for the efficient drawing of constraint - satisfying samples online without any need for modification of available sampling - based motion planning algorithms. we evaluate the efficiency of these two generative models in terms of their sampling accuracy and coverage of sampling distribution. simulations and experiments are also conducted for different constraint tasks on two robotic platforms.
|
arxiv:2204.06791
|
in this article we provide an identification between the wavelet decompositions of certain fractal representations of $ c ^ * - $ algebras of directed graphs of m. marcolli and a. paolucci, and the eigenspaces of laplacians associated to spectral triples constructed from cantor fractal sets that are the infinite path spaces of bratteli diagrams associated to the representations, with a particular emphasis on wavelets for representations of $ \ mathcal { o } _ d $. in particular, in this setting we use results of j. pearson and j. bellissard, and a. julien and j. savinien, to construct first the spectral triple and then the laplace beltrami operator on the associated cantor set. we then prove that in certain cases, the orthogonal wavelet decomposition and the decomposition via orthogonal eigenspaces match up precisely. we give several explicit examples, including an example related to a sierpinski fractal, and compute in detail all the eigenvalues and corresponding eigenspaces of the laplace beltrami operators for the equal weight case for representations of cuntz algebras, and in the uneven weight case for certain representations of $ \ mathcal { o } _ 2 $, and show how the eigenspaces and wavelet subspaces at different levels are related.
|
arxiv:1603.06979
|
diffusion models are capable of impressive feats of image generation with uncommon juxtapositions such as astronauts riding horses on the moon with properly placed shadows. these outputs indicate the ability to perform compositional generalization, but how do the models do so? we perform controlled experiments on conditional ddpms learning to generate 2d spherical gaussian bumps centered at specified $ x $ - and $ y $ - positions. our results show that the emergence of semantically meaningful latent representations is key to achieving high performance. en route to successful performance over learning, the model traverses three distinct phases of latent representations : ( phase a ) no latent structure, ( phase b ) a 2d manifold of disordered states, and ( phase c ) a 2d ordered manifold. corresponding to each of these phases, we identify qualitatively different generation behaviors : 1 ) multiple bumps are generated, 2 ) one bump is generated but at inaccurate $ x $ and $ y $ locations, 3 ) a bump is generated at the correct $ x $ and y location. furthermore, we show that even under imbalanced datasets where features ( $ x $ - versus $ y $ - positions ) are represented with skewed frequencies, the learning process for $ x $ and $ y $ is coupled rather than factorized, demonstrating that simple vanilla - flavored diffusion models cannot learn efficient representations in which localization in $ x $ and $ y $ are factorized into separate 1d tasks. these findings suggest the need for future work to find inductive biases that will push generative models to discover and exploit factorizable independent structures in their inputs, which will be required to vault these models into more data - efficient regimes.
|
arxiv:2402.03305
|
in this paper arithmetic progressions on the integers and the integers modulo n are extended to graphs. this allows for the definition of the anti - van der waerden number of a graph. much of the focus of this paper is on 3 - term arithmetic progressions for which general bounds are obtained based on the radius and diameter of a graph. the general bounds are improved for trees and cartesian products and exact values are determined for some classes of graphs. larger k - term arithmetic progressions are considered and a connection between the ramsey number of paths and the anti - van der waerden number of graphs is established.
|
arxiv:1802.01509
|
we propose a novel method for effective retrieval of multi - agent spatiotemporal tracking data. retrieval of spatiotemporal tracking data offers several unique challenges compared to conventional text - based retrieval settings. most notably, the data is fine - grained meaning that the specific location of agents is important in describing behavior. additionally, the data often contains tracks of multiple agents ( e. g., multiple players in a sports game ), which generally leads to a permutational alignment problem when performing relevance estimation. due to the frequent position swap of agents, it is difficult to maintain the correspondence of agents, and such issues make the pairwise comparison problematic for multi - agent spatiotemporal data. to address this issue, we propose a tree - based method to estimate the relevance between multi - agent spatiotemporal tracks. it uses a hierarchical structure to perform multi - agent data alignment and partitioning in a coarse - to - fine fashion. we validate our approach via user studies with domain experts. our results show that our method boosts performance in retrieving similar sports plays - - especially in interactive situations where the user selects a subset of trajectories compared to current state - of - the - art methods.
|
arxiv:1710.02255
|
operators on the ring of algebraically constructible functions are used to compute local obstructions for a four - dimensional semialgebraic set to be homeomorphic to a real algebraic set. the link operator and arithmetic operators yield $ 2 ^ { 43 } - 43 $ independent characteristic numbers mod 2, which generalize the akbulut - king numbers in dimension three.
|
arxiv:math/9809060
|
we explore power spectrum estimation in the context of a gaussian approximation to the likelihood function. using the saskatoon data, we estimate the power averaged through a set of ten filters designed to make the errors on the power estimates uncorrelated. we also present an improvement to using the window function, $ w _ l $, for calculating bandpower estimates.
|
arxiv:astro-ph/9702110
|
we have investigated structure and properties of small metal clusters using all - electron ab initio theoretical methods based on the hartree - fock approximation and density functional theory, perturbation theory and compared results of our calculations with the available experimental data and the results of other theoretical works. we have systematically calculated the optimized geometries of neutral and singly charged sodium clusters having up to 20 atoms, their multipole moments ( dipole and quadrupole ), static polarizabilities, binding energies per atom, ionization potentials and frequencies of normal vibration modes. our calculations demonstrate the great role of many - electron correlations in the formation of electronic and ionic structure of small metal clusters and form a good basis for further detailed study of their dynamic properties, as well as structure and properties of other atomic cluster systems.
|
arxiv:physics/0112038
|
we consider spin hall effect in a system of massless dirac fermions in a graphene lattice. two types of spin - orbit interaction, pertinent to the graphene lattice, are taken into account - the intrinsic and rashba terms. assuming perfect crystal lattice, we calculate the topological contribution to spin hall conductivity. when both interactions are present, their interplay is shown to lead to some peculiarities in the dependence of spin hall conductivity on the fermi level.
|
arxiv:0910.5352
|
size is a fundamental parameter for measuring the growth of galaxies and the role of the environment on their evolution. however, the conventional size definitions used for this purpose are often biased and miss the diffuse, outermost signatures of galaxy growth, including star formation and gas accretion. this issue is addressed by examining low surface brightness truncations or galaxy ` ` edges ' ' as a physically motivated tracer of size based on star formation thresholds. our total sample consists of $ \ sim900 $ galaxies with stellar masses ranging from $ 10 ^ 5 m _ { \ odot } < m _ { \ star } < 10 ^ { 11 } m _ { \ odot } $. this sample of nearby cluster, group satellite and nearly isolated field galaxies was compiled using multi - band imaging from the fornax deep survey, deep iac stripe 82 and dark energy camera legacy surveys. we find that the edge radii scale as $ r _ { \ rm edge } \ propto m _ { \ star } ^ { 0. 42 } $ with a very small intrinsic scatter ( $ \ sim 0. 07 $ dex ). the scatter is driven by the morphology and environment of galaxies. in both the cluster and field, early - type dwarfs are systematically smaller by $ \ sim20 \ % $ than the late - types. however, compared to the field galaxies in the fornax cluster are the most impacted. at a fixed stellar mass, edges in the cluster can be found at $ \ sim $ 50 \ % smaller radii and the average stellar surface density at the edges is a factor of two higher $ \ sim 1 \, m _ { \ odot } $ / pc $ ^ 2 $. our findings support the rapid removal of loosely bound neutral hydrogen in hot, crowded environments which truncates galaxies outside - in earlier, preventing the formation of more extended sizes and lower density edges. our results highlight the importance of deep imaging surveys to study the low surface brightness imprints of the large scale structure and environment on galaxy evolution.
|
arxiv:2311.10144
|
floods affected more than 2 billion people worldwide from 1998 to 2017 and their occurrence is expected to increase due to climate warming, population growth and rapid urbanization. recent approaches for understanding the resilience of transportation networks when facing floods mostly use the framework of percolation but we show here on a realistic high - resolution flood simulation that it is inadequate. indeed, the giant connected component is not relevant and instead, we propose to partition the road network in terms of accessibility of local towns and define new measures that characterize the impact of the flooding event. our analysis allows to identify cities that will be pivotal during the flooding by providing to a large number of individuals critical services such as hospitalization services, food supply, etc. this approach is particularly relevant for practical risk management and will help decision makers for allocating resources in space and time.
|
arxiv:2202.00292
|
the purpose of this paper is to introduce a new way to inquire the quantum cosmology for a certain gravitational theory. normally, the quantum cosmological model is introduced as the minisuperspace theory which is obtained by reducing the superspace where the wheel - dewitt equation is defined on using the symmetry provided by cosmological principle. unlike that, the key of our approach is to reinterpret the cosmology in a classical dynamical way using a point - like lagrangian and then quantize the point - like model. we apply the method into einstein gravity, gravity with a cosmological constant and the $ f ( r ) $ - gravity, and get their wave equations respectively. by analsysing the exact solution for the quantum cosmology with and without a cosmological constant we demonstrate that the cosmological constant is essential and being a tiny positive number. we also show the possibility of explaining inflation under the quantum version of cosmology.
|
arxiv:1504.04838
|
a simple yet accurate model for the transmission of surface plasmon polaritons ( spps ) in a finite metal - insulator - metal ( mim ) waveguide to the sides of the apertures is proposed and demonstrated to be more accurate than available models. it is as simple as using a magnetic current density across the plane of the aperture whose value is defined by spps with any number of modes in the waveguide through the equivalence principle. then, the generated spps on the both sides of the aperture are extracted from the convolution integral of the equivalent current density and green ' s function. as a result, the model provides the transmission coefficients of spps in the mim to the side walls of the aperture accurately and efficiently ; not only for symmetric mims with a single isolating layer but also for non - symmetric ones with multi - layered insulating materials. the results are in very good agreement with those obtained by the fdtd method and better than the other approximations available in literature for a wide range of aperture widths.
|
arxiv:2210.14844
|
as a blockchain platform that has developed vigorously in recent years, ethereum is different from bitcoin in that it introduces smart contracts into blockchain. solidity is one of the most mature and widely used smart contract programming language, which is used to write smart contracts and deploy them on blockchain. however, once the data in the blockchain is written, it cannot be modified. ethereum smart contract is stored in the block chain, which makes the smart contract can no longer repair the code problems such as re - entrancy vulnerabilities or integer overflow problems. currently, there still lacks of an efficient and effective approach for detecting these problems in solidity. in this paper, we first classify all the possible problems in solidity, then propose a smart contract problem detection approach for solidity, namely soliditycheck. the approach uses regular expressions to define the characteristics of problematic statements and uses regular matching and program instrumentation to prevent or detect problems. finally, a large number of experiments is performed to show that soliditycheck is superior to existing approaches.
|
arxiv:1911.09425
|
we present the results of osse observations of the soft gamma ray continuum emission from the galactic plane at longitude 95 degrees. emission is detected between 50 and 600 kev where the spectrum is fit well by a power law with photon index - 2. 6 + - 0. 3 and flux ( 4. 0 + - 0. 5 ) 10 ^ { - 2 } photons / s / cm ^ 2 / rad / mev at 100 kev. this spectral shape in this range is similar to that found for the continuum emission from the inner galaxy but the amplitude is lower by a factor of four. this emission is either due to unresolved and previously unknown point sources or it is of diffuse origin, or a combination of the two. simultaneous observations with osse and smaller field of view instruments operating in the soft gamma ray energy band, such as xte or sax, would help resolve this issue. if it is primarily diffuse emission due to nonthermal electron bremsstrahlung, as is the > 1 mev galactic ridge continuum, then the power in low energy cosmic ray electrons exceeds that of the nuclear component of the cosmic rays by an order of magnitude. this would have profound implications for the origin of cosmic rays and the energetics of the interstellar medium. alternatively, if the emission is diffuse and thermal, then there must be a component of the interstellar medium at temperatures near 10 ^ 9 k.
|
arxiv:astro-ph/9704207
|
large language models ( llms ) possess a wealth of knowledge encoded in their parameters. however, this knowledge may become outdated or unsuitable over time. as a result, there has been a growing interest in knowledge editing for llms and evaluating its effectiveness. existing studies primarily focus on knowledge editing using factual triplets, which not only incur high costs for collection but also struggle to express complex facts. furthermore, these studies are often limited in their evaluation perspectives. in this paper, we propose eva - kellm, a new benchmark for evaluating knowledge editing of llms. this benchmark includes an evaluation framework and a corresponding dataset. under our framework, we first ask the llm to perform knowledge editing using raw documents, which provides a more convenient and universal approach compared to using factual triplets. we then evaluate the updated llm from multiple perspectives. in addition to assessing the effectiveness of knowledge editing and the retention of unrelated knowledge from conventional studies, we further test the llm ' s ability in two aspects : 1 ) reasoning with the altered knowledge, aiming for the llm to genuinely learn the altered knowledge instead of simply memorizing it. 2 ) cross - lingual knowledge transfer, where the llm updated with raw documents in one language should be capable of handling queries from another language. to facilitate further research, we construct and release the corresponding dataset. using this benchmark, we investigate the effectiveness of several commonly - used knowledge editing methods. experimental results indicate that the current methods for knowledge editing using raw documents are not effective in yielding satisfactory results, particularly when it comes to reasoning with altered knowledge and cross - lingual knowledge transfer.
|
arxiv:2308.09954
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.