text
stringlengths 1
3.65k
| source
stringlengths 15
79
|
|---|---|
it is shown that in the large - n _ c limit radial regge trajectories give rise in a natural way to the presence of the dimension - 2 gluon condensate, < a ^ 2 >, in meson correlators. we match these models to qcd and provide estimates for < a ^ 2 > in terms of other physical quantities. in particular, in the simplest strictly linear radial regge model with equal residues < a ^ 2 > is proportional to the pion decay constant squared. however, the linear model fails a consistency condition based on matching the short - and long - distance string tensions, nor reproduces the phenomenological values of the gluon condensates. on the contrary, in regge models departing from strict linearity one may reproduce both the consistency condition and the signs of condensates. we demonstrate this in a simple explicit model.
|
arxiv:hep-ph/0603263
|
this paper has been withdrawn by the corresponding author because the newest version is now published in journal of discrete algorithms.
|
arxiv:0802.0314
|
the term " light dragging " describes how the trajectory of light changes as it travels through a moving medium. this phenomenon facilitates the precise detection of incredibly slow speeds of light, which is widely used in quantum gate operations, state transfer, and quantum memory implementations, etc. to the best of our knowledge, this is the first time we have proposed the existence of a light - dragging effect in a magnomechanical system ( mms ). the origin of this crucial element stems from nonlinear dipole and magnetostrictive interactions in mms. magnomechanical characteristics such as magnon - photon and magnon - phonon couplings have a strong impact on both refractive and group index profile spectra. we also explore that lateral light drag shows a strong dependence on detuning by altering the amplitude and direction of the translational velocity. this enabled us to alter the light ' s propagation within the magnomechanical system from superluminal to subluminal and vice versa by adjusting the probe ' s detuning. the ability to control and manipulate the light drag through the mms could be helpful in designing novel devices with improved functionality at the microscopic scale.
|
arxiv:2503.09751
|
understanding and engineering the coupling of spins in nanomaterials is of central importance for designing novel devices. graphene nanostructures with { \ pi } - magnetism offer a chemically tunable platform to explore quantum magnetic interactions. however, realizing spin chains bearing controlled odd - even effects with suitable nanographene systems is challenging. here, we demonstrate the successful on - surface synthesis of spin - 1 / 2 antiferromagnetic heisenberg chains with parity - dependent magnetization based on antiaromatic diaza - hexa - peri - hexabenzocoronene ( diaza - hbc ) units. using distinct synthetic strategies, two types of spin chains with different terminals were synthesized, both exhibiting a robust odd - even effect on the spin coupling along the chain. combined investigations using scanning tunneling microscopy, non - contact atomic force microscopy, density functional theory calculations, and quantum spin models confirmed the structures of the diaza - hbc chains and revealed their magnetic properties, which has an s = 1 / 2 spin per unit through electron donation from the diaza - hbc core to the au ( 111 ) substrate. gapped excitations were observed in even - numbered chains, while enhanced kondo resonance emerged in odd - numbered units of odd - numbered chains due to the redistribution of the unpaired spin along the chain. our findings provide an effective strategy to construct nanographene spin chains and unveil the odd - even effect in their magnetic properties, offering potential applications in nanoscale spintronics.
|
arxiv:2407.20511
|
the aim of this paper is to make clear and precise the relationship between the rubin causal model ( rcm ) and structural causal model ( scm ) frameworks for causal inference. adopting a neutral logical perspective, and drawing on previous work, we show what is required for an rcm to be representable by an scm. a key result then shows that every rcm - - including those that violate algebraic principles implied by the scm framework - - emerges as an abstraction of some representable rcm. finally, we illustrate the power of this conciliatory perspective by pinpointing an important role for scm principles in classic applications of rcms ; conversely, we offer a characterization of the algebraic constraints implied by a graph, helping to substantiate further comparisons between the two frameworks.
|
arxiv:2306.14351
|
this paper investigates the problem of inferring knowledge from data so that the inferred knowledge is interpretable and informative to humans who have prior knowledge. given a dataset as a collection of system trajectories, we infer parametric linear temporal logic ( pltl ) formulas that are informative and satisfied by the trajectories in the dataset with high probability. the informativeness of the inferred formula is measured by the information gain with respect to given prior knowledge represented by a prior probability distribution. we first present two algorithms to compute the information gain with a focus on two types of prior probability distributions : stationary probability distributions and probability distributions expressed by discrete time markov chains. then we provide a method to solve the inference problem for a subset of pltl formulas with polynomial time complexity with respect to the number of boolean connectives in the formula. we provide implementations of the proposed approach on explaining anomalous patterns, patterns changes and explaining the policies of markov decision processes.
|
arxiv:1811.08846
|
we report on the magnetic, transport, and thermal properties of the hexagonal zrnial - type compound cemgin with ce atoms forming a distorted kagome network. this compound exhibits successive antiferromagnetic transition at $ t _ \ text { n1 } = $ 2. 1 k, $ t _ \ text { n2 } = $ 1. 7 k, and possibly $ t _ \ text { n3 } = $ 1. 3 k. the electrical resistivity exhibits a minimum at 11 k and a nonlogarithmic increase with decreasing temperature down to $ t _ \ text { n2 } $. we found that cemgin is the first zrnial - type compound whose resistivity increase can be well explained by considering a model in which the electron - spin scattering is enhanced by the magnetic frustration and the ruderman - kittel - kasuya - yosida interaction. these results suggest that cemgin is a notable compound whose physical properties are strongly affected by geometrical frustration. since the sommerfeld coefficient is 97 mj / mol k $ ^ 2 $, cemgin is classified as a moderate heavy - fermion compound.
|
arxiv:2504.03186
|
we proposed a proof of the riemann hypothesis. the proof is based on the nyman - beurling - baez - duarte condition. by proving existence of the solution for a system of inequalities, we can show that there is a sequence, which act as the coefficient of beurling ' s sequence, can approximate the constant vector in a weighted hilbert space.
|
arxiv:2310.03972
|
we present reduced data and data products from the 3d - hst survey, a 248 - orbit hst treasury program. the survey obtained wfc3 g141 grism spectroscopy in four of the five candels fields : aegis, cosmos, goods - s, and uds, along with wfc3 $ h _ { 140 } $ imaging, parallel acs g800l spectroscopy, and parallel $ i _ { 814 } $ imaging. in a previous paper ( skelton et al. 2014 ) we presented photometric catalogs in these four fields and in goods - n, the fifth candels field. here we describe and present the wfc3 g141 spectroscopic data, again augmented with data from go - 1600 in goods - n. the data analysis is complicated by the fact that no slits are used : all objects in the wfc3 field are dispersed, and many spectra overlap. we developed software to automatically and optimally extract interlaced 2d and 1d spectra for all objects in the skelton et al. ( 2014 ) photometric catalogs. the 2d spectra and the multi - band photometry were fit simultaneously to determine redshifts and emission line strengths, taking the morphology of the galaxies explicitly into account. the resulting catalog has 98, 663 measured redshifts and line strengths down to $ jh _ { ir } \ leq 26 $ and 22, 548 with $ jh _ { ir } \ leq 24 $, where we comfortably detect continuum emission. of this sample 5, 459 galaxies are at $ z > 1. 5 $ and 9, 621 are at $ 0. 7 < z < 1. 5 $, where h $ \ alpha $ falls in the g141 wavelength coverage. based on comparisons with ground - based spectroscopic redshifts, and on analyses of paired galaxies and repeat observations, the typical redshift error for $ jh _ { ir } \ leq 24 $ galaxies in our catalog is $ \ sigma _ z \ approx 0. 003 \ times ( 1 + z ) $, i. e., one native wfc3 pixel. the $ 3 \ sigma $ limit for emission line fluxes of point sources is $ 1. 5 \ times10 ^ { - 17 } $ ergs s $ ^ { - 1 } $ cm $ ^ { - 2 } $. we show various representations of the full dataset, as well as individual examples that
|
arxiv:1510.02106
|
we investigate consequences of a continuously energy - injecting central engine of gamma - ray burst ( grb ) afterglow emission, assuming that a highly magnetized pulsar is left beaming in the core of a grb progenitor. beaming and continuous energy - injection are natural consequences of the pulsar origin of grb afterglows. whereas previous studies have considered continuous energy - injection from a new - born pulsar to interpret the deviation of afterglow light curves of grbs from those with the simple power law behavior, a beaming effect, which is one of the most important aspects of pulsar emissions, is ignored in earlier investigations. we explicitly include the beaming effect and consider a change of the beaming with time due to a dynamical evolution of a new - born pulsar. we show that the magnitude of the afterglow from this fireball indeed first decreases with time, subsequently rises, and declines again. one of the most peculiar optical afterglows light curve of grb 970508 can be accounted for by continuous energy injection with beaming due to a highly magnetized new - born pulsar. we discuss implications on such observational evidence for a pulsar.
|
arxiv:astro-ph/0110640
|
we measure cross sections for residual nuclide formation in the mass range 6 < a < 97 caused by bombardment with protons and deuterons of 3. 65 gev / nucleon energy of enriched tin isotopes ( 112 - sn, 118 - sn, 120 - sn, 124 - sn ). the experimental data are compared with calculations by the codes fluka, lahet, cem03, and laqgsm03. scaling behavior is observed for the whole mass region of residual nuclei, showing a possible multifragmentation mechanism for the formation of light products ( 6 < a < 31 ). our analysis of the isoscaling dependence also shows a possible contribution of multifragmentation to the production of heavier nuclides, in the mass region 39 < a < 81.
|
arxiv:nucl-ex/0506024
|
observations at millimetre wavelengths provide a valuable tool to study the small scale dynamics in the solar chromosphere. we evaluate the physical conditions of the atmosphere in the presence of a propagating shock wave and link that to the observable signatures in mm - wavelength radiation, providing valuable insights into the underlying physics of mm - wavelength observations. a realistic numerical simulation from the 3d radiative magnetohydrodynamic ( mhd ) code bifrost is used to interpret changes in the atmosphere caused by shock wave propagation. high - cadence ( 1 s ) time series of brightness temperature ( t $ _ \ text { b } $ ) maps are calculated with the advanced radiative transfer ( art ) code at the wavelengths $ 1. 309 $ mm and $ 1. 204 $ mm, which represents opposite sides of spectral band ~ $ 6 $ of the atacama large millimeter / submillimeter array ( alma ). an example of shock wave propagation is presented. the brightness temperatures show a strong shock wave signature with large variation in formation height between $ \ sim0. 7 $ to $ 1. 4 $ mm. the results demonstrate that millimetre brightness temperatures efficiently track upwardly propagating shock waves in the middle chromosphere. in addition, we show that the gradient of the brightness temperature between wavelengths within alma band $ 6 $ can potentially be utilised as a diagnostics tool in understanding the small - scale dynamics at the sampled layers.
|
arxiv:2008.05324
|
we study radiation from charged particles in circular motion around a schwarzschild black hole immersed in an asymptotically uniform magnetic field. in curved space, the radiation reaction force is described by the dewitt - brehme equation, which includes a complicated, non - local tail term. we show that, contrary to some claims in the literature, this term cannot, in general, be neglected. we account for self - force effects directly by calculating the electromagnetic energy flux at infinity and on the horizon. the radiative field is obtained using black hole perturbation theory. we solve the relevant equations analytically, in the low - frequency and slow - motion approximation, as well as numerically in the general case. our results show that great care must be taken when neglecting the tail term, which is often fundamental to capture the dynamics of the particle : in fact, it only seems to be negligible when the magnetic force greatly dominates the gravitational force, so that the motion is well described by the abraham - - lorentz - - dirac equation. we also report a curious " horizon dominance effect " that occurs for a radiating particle in a circular orbit around a black hole ( emitting either scalar, electromagnetic or gravitational waves ) : for fixed orbital radius, the fraction of energy that is absorbed by the black hole can be made arbitrarily large by decreasing the particle velocity.
|
arxiv:2404.02195
|
transverse momentum dependent distribution and fragmentation functions of unpolarized quarks inside unpolarized protons are extracted, for the first time, through a simultaneous analysis of semi - inclusive deep - inelastic scattering, drell - yan and $ z $ boson hadroproduction processes. this study is performed at leading order in perturbative qcd, with energy scale evolution at the next - to - leading logarithmic accuracy. moreover, some specific choices are made to deal with low scale evolution around 1 gev $ ^ 2 $. since only data in the low transverse momentum region are considered, no matching to fixed - order calculations at high transverse momentum is needed.
|
arxiv:1801.08443
|
current motion capture ( mocap ) systems generally require markers and multiple calibrated cameras, which can be used only in constrained environments. in this work we introduce a drone - based system for 3d human mocap. the system only needs an autonomously flying drone with an on - board rgb camera and is usable in various indoor and outdoor environments. a reconstruction algorithm is developed to recover full - body motion from the video recorded by the drone. we argue that, besides the capability of tracking a moving subject, a flying drone also provides fast varying viewpoints, which is beneficial for motion reconstruction. we evaluate the accuracy of the proposed system using our new drocap dataset and also demonstrate its applicability for mocap in the wild using a consumer drone.
|
arxiv:1804.06112
|
enhancing motivation and learning attitudes in an introductory physics course is an important but difficult task that can be achieved through class blogging. we incorporated into an introductory course a blog operated by upper - level physics students. using the colorado learning attitudes about science survey ( class ), periodic in - class surveys, analysis of student blog comments, and post - instructional interviews, we evaluate how the blog combined with class instruction provided the students with a better sense of relevance and confidence and outline recommendations for future use of this strategy.
|
arxiv:1108.1591
|
in machine learning or statistics, it is often desirable to reduce the dimensionality of a sample of data points in a high dimensional space $ \ mathbb { r } ^ d $. this paper introduces a dimensionality reduction method where the embedding coordinates are the eigenvectors of a positive semi - definite kernel obtained as the solution of an infinite dimensional analogue of a semi - definite program. this embedding is adaptive and non - linear. we discuss this problem both with weak and strong smoothness assumptions about the learned kernel. a main feature of our approach is the existence of an out - of - sample extension formula of the embedding coordinates in both cases. this extrapolation formula yields an extension of the kernel matrix to a data - dependent mercer kernel function. our empirical results indicate that this embedding method is more robust with respect to the influence of outliers, compared with a spectral embedding method.
|
arxiv:1711.07271
|
. geo bag material is typically composed of geotextile fabric and can be designed for different specifications. = = best management practices = = in order to incorporate principles of soft engineering into practice, shorelines must be redeveloped to achieve multiple objectives. for example, soft shoreline engineering has the ability to decrease costs, stabilize banks, enhance aesthetic value, protect riparian habitats, expand public access, and support a diversity of wildlife. to achieve the goal of multiple objectives for waterfront development and design, a multi - disciplinary team must be formed to integrate environmental, social, and economic principles. the first step in implementing soft engineering is conducting a preliminary assessment of the site and determining whether soft engineering is applicable and practical. a typical assessment includes identifying the extent of the project area, evaluating existing uses, documenting amenities and characteristics such as habitats, species, public access, development, and considering impact of future desired use. if the team decides the site is fit to implement soft engineering, a complex process is designed in order to achieve the predetermined goals of the development and complete with objectives. standards and targets must then be created to measure project development and progress. interdisciplinary partnerships must be established at an early stage in the process to ensure the incorporation of environmental, social, and economic values, as well as target objectives implemented to measure progress. priorities and alternative are established, with the team working together to decide on the best management practices to achieve maximum effectiveness. after best management practices have been determined and incorporated, project success is based upon the meeting of objectives and effective preservation and conservation efforts. = = case studies = = = = = greater detroit american heritage river initiative = = = in 1998, the president of the united states created the american heritage river initiative to restore and revitalize rivers and waterfronts through the use of newly introduced soft engineering techniques. a report by schneider reported that 47. 2 % of the u. s. and canadian detroit river had been fortified with concrete or steel, in accordance with traditional hard engineering management practices. in 1999, a u. s. canadian sse conference developed the best management practices for sse use, which was put into effect among the 38 sse projects that took place in the detroit river - western lake erie watershed. a grand total of $ 17. 3 million was spent on these projects which aimed to improve riparian and aquatic habitat, restore natural shoreline, and treat stormwater. the study found that the economic benefits to ecological restoration are profound and provide compelling evidence for further investigation and investment into shoreline rehabilitation processes. researchers also found that
|
https://en.wikipedia.org/wiki/Soft_engineering
|
covid - 19 pandemic tested the capacity of information systems in countries on the ability to rapidly respond to requirements which were not anticipated. this article analyzes the socio - technical determinants of agility in building the is response to the covid - 19 pandemic in sri lanka. we deploy qualitative research methods to explore the case study of implementation of covid - 19 surveillance system in sri lanka. three key recommendations are developed for practice relating to high - level multisectoral governance, use of lightweight digital platforms and leveraging on existing capacities and infrastructure.
|
arxiv:2108.09727
|
the aim of this paper is to study a one dimensional model system of equations for ionized gas dynamics at high temperature where the gas is a mixture of two kinds of monatomic gas. in addition to the mass density, pressure, temperature and particle velocity, degrees of ionization of both gases are also involved. by assuming that the local thermal equilibrium is attained, saha ' s ionization equations are added. thus the equations are supplemented by the first and second law of thermodynamics, a single equation of state and, in addition, a set of thermodynamic equations. the equations constitute a strictly hyperbolic system, which guarantees that the initial value problem is well - posed locally in time for sufficiently smooth initial data. however the geometric properties of the system are rather complicated : in particular, we prove the existence of a region where convexity ( genuine nonlinearity ) fails for forward and backward characteristic fields. also we study thermodynamic properties of shock waves by a detailed analysis of the hugoniot locus, which is used in a mathematical study of existence and uniqueness of solutions to the shock tube problem.
|
arxiv:1911.11003
|
recent calculations have shown that the linear proportionality between black hole entropy and area can be explained by performing a density matrix calculation for a massless free field theory. by applying the same formalism to an empirical fluid ` ` field theory, ' ' entropic quantities such as surface tension can be calculated in a novel fashion. good agreement with experiment is obtained for a number of liquids. this approach may lead to a practical new technique for the evaluation of thermodynamic quantities important entropic components. implications for the protein folding problem are discussed.
|
arxiv:cond-mat/9601111
|
reliable long - time storage of arbitrary quantum states is a key element for quantum information processing. in order to dynamically decouple a spin or quantum bit from a dephasing environment, we introduce an optimized sequence of $ n $ control pulses of finite durations $ \ tau \ pp $ and finite amplitudes. the properties of this sequence of length $ t $ stem from a mathematically rigorous derivation. corrections occur only in order $ t ^ { n + 1 } $ and $ \ tau \ pp ^ 3 $ without mixed terms such as $ t ^ n \ tau \ pp $ or $ t ^ n \ tau \ pp ^ 2 $. based on existing experiments, a concrete setup for the verification of the properties of the advocated realistic sequence is proposed.
|
arxiv:0906.3605
|
given a graph g and an integer k, two players take turns coloring the vertices of g one by one using k colors so that neighboring vertices get different colors. the first player wins iff at the end of the game all the vertices of $ g $ are colored. the game chromatic number \ chi _ g ( g ) is the minimum k for which the first player has a winning strategy. the paper \ cite { bfs } began the analysis of the asymptotic behavior of this parameter for a random graph g _ { n, p }. this paper provides some further analysis for graphs with constant average degree i. e. np = o ( 1 ) and for random regular graphs.
|
arxiv:1201.0046
|
as it is known, finitely presented quivers correspond to dynkin graphs ( gabriel, 1972 ) and tame quivers - - to extended dynkin graphs ( donovan and freislich, nazarova, 1973 ). in the article " locally scalar reresentations of graphs in the category of hilbers spaces " ( func. anal. and appl., 2005 ) authors showed the way to tranfer these results to hilbert spaces, constructed coxeter functors and proved an analogue of gabriel theorem fol locally scalar ( orthoscalar in the sequel ) representations ( up to the unitary equivalence ). the category of orthoscalar representations of a quiver can be considered as a subcategory in the category of all representations ( over a field $ \ mathbb c $ ). in the present paper we study the connection between indecomposable orthoscalar representations in the subcategory and in the category of all representations. for the quivers, corresponded to extended dynkin graphs, orthoscalar representations which cannot be obtained from the simplest by coxeter functors ( regular representations ) are classified.
|
arxiv:0901.2296
|
maximal monotonicity is explored as a generalization of the linear theory of passivity, aiming at an algorithmic input / output analysis of physical models. the theory is developed for maximal monotone one - port circuits, formed by the series and parallel interconnection of basic elements. these circuits generalize passive lti transfer functions. periodic input signals are shown to be mapped to periodic output signals, and these input - output behaviors can be efficiently computed using a maximal monotone splitting algorithm, which decomposes the computation according to the circuit topology. a new splitting algorithm is presented, which applies to any monotone one - port circuit defined as a port interconnection of monotone elements.
|
arxiv:2111.15407
|
we prove that the zero - fiber of the moment map of a totally negative quiver has rational singularities. our proof consists in generalizing dimension bounds on jet spaces of this fiber, which were introduced by budur. we also transfer the rational singularities property to other moduli spaces of objects in 2 - calabi - yau categories, based on recent work of davison. this has interesting arithmetic applications on quiver moment maps and moduli spaces of objects in 2 - calabi - yau categories. first, we generalize results of wyss on the asymptotic behaviour of counts of jets of quiver moment maps over finite fields. moreover, we interpret the limit of counts of jets on a given moduli space as its p - adic volume under a canonical measure analogous to the measure built by carocci, orecchia and wyss on certain moduli spaces of coherent sheaves.
|
arxiv:2209.14791
|
we present a novel framework to explore neural control and design of complex fluidic systems with dynamic solid boundaries. our system features a fast differentiable navier - stokes solver with solid - fluid interface handling, a low - dimensional differentiable parametric geometry representation, a control - shape co - design algorithm, and gym - like simulation environments to facilitate various fluidic control design applications. additionally, we present a benchmark of design, control, and learning tasks on high - fidelity, high - resolution dynamic fluid environments that pose challenges for existing differentiable fluid simulators. these tasks include designing the control of artificial hearts, identifying robotic end - effector shapes, and controlling a fluid gate. by seamlessly incorporating our differentiable fluid simulator into a learning framework, we demonstrate successful design, control, and learning results that surpass gradient - free solutions in these benchmark tasks.
|
arxiv:2405.14903
|
we examine the cancellation mechanism between the different contributions to the electric dipole moment of the neutron in a model with dilaton - dominated susy breaking. we find these accidental cancellations occur at few points in parameter space. for a wide region of this space we must constrain the phase of $ \ mu $ to be of order $ 10 ^ { - 1 } $ and have the phases of $ a $ and $ \ mu $ strongly correlated in order to have small neutron edm. moreover, we consider the indirect cp violation parameter $ \ epsilon $ in this region where the electric dipole moment is less than the experimental limit and find that we can generate $ \ epsilon $ of order $ 10 ^ { - 6 } $.
|
arxiv:hep-ph/9903425
|
we notice that the existing literature about the reaction e + e - - - > hh suffers from a mistake in the relative sign between the t - channel and u - channel graphs. correcting this lowers the crosssections by about an order of magnitude.
|
arxiv:0812.3750
|
supercuspidal representations are usually infinite - dimensional, so the size of such a representation cannot be measured by its dimension ; the formal degree is a better alternative. hiraga, ichino, and ikeda conjectured a formula for the formal degree of a supercuspidal in terms of its $ l $ - parameter only. our first main result is to compute the formal degrees of the supercuspidal representations constructed by yu. our second, using the first, is to verify that kaletha ' s regular supercuspidal $ l $ - packets satisfy the conjecture.
|
arxiv:2101.00658
|
in a valuation domain $ ( v, m ) $ every nonzero finitely generated ideal $ j $ is principal and so, in particular, $ j = j ^ t $, hence the maximal ideal $ m $ is a $ t $ - ideal. therefore, the $ t $ - local domains ( i. e., the local domains, with maximal ideal being a $ t $ - ideal ) are " cousins " of valuation domains, but, as we will see in detail, not so close. indeed, for instance, a localization of a $ t $ - local domain is not necessarily $ t $ - local, but of course a localization of a valuation domain is a valuation domain. so it is natural to ask under what conditions is a $ t $ - local domain a valuation domain? the main purpose of the present paper is to address this question, surveying in part previous work by various authors containing useful properties for applying them to our goal.
|
arxiv:1812.03713
|
the hamiltonian analysis for the chern - simons theory and pontryagin invariant, which depends of a connection valued in the lie algebra of so ( 3, 1 ), is performed. by applying a pure dirac ' s method we find for both theories the extended hamiltonian, the extended action, the constraint algebra, the gauge transformations and we carry out the counting of degrees of freedom. from the results obtained in the present analysis, we will conclude that the theories under study have a closed relation among its constraints and defines a topological field theory. in addition, we extends the configuration space for the pontryagin theory and we develop the hamiltonian analysis for this modified version, finding a best description of the results previously obtained.
|
arxiv:1107.4023
|
mechanism, an early known mechanical analog computer, and the mechanical inventions of archimedes, are examples of greek mechanical engineering. some of archimedes ' inventions, as well as the antikythera mechanism, required sophisticated knowledge of differential gearing or epicyclic gearing, two key principles in machine theory that helped design the gear trains of the industrial revolution, and are widely used in fields such as robotics and automotive engineering. ancient chinese, greek, roman and hunnic armies employed military machines and inventions such as artillery which was developed by the greeks around the 4th century bc, the trireme, the ballista and the catapult, the trebuchet by chinese circa 6th - 5th century bce. = = = middle ages = = = the earliest practical wind - powered machines, the windmill and wind pump, first appeared in the muslim world during the islamic golden age, in what are now iran, afghanistan, and pakistan, by the 9th century ad. the earliest practical steam - powered machine was a steam jack driven by a steam turbine, described in 1551 by taqi al - din muhammad ibn ma ' ruf in ottoman egypt. the cotton gin was invented in india by the 6th century ad, and the spinning wheel was invented in the islamic world by the early 11th century, both of which were fundamental to the growth of the cotton industry. the spinning wheel was also a precursor to the spinning jenny, which was a key development during the early industrial revolution in the 18th century. the earliest programmable machines were developed in the muslim world. a music sequencer, a programmable musical instrument, was the earliest type of programmable machine. the first music sequencer was an automated flute player invented by the banu musa brothers, described in their book of ingenious devices, in the 9th century. in 1206, al - jazari invented programmable automata / robots. he described four automaton musicians, including drummers operated by a programmable drum machine, where they could be made to play different rhythms and different drum patterns. before the development of modern engineering, mathematics was used by artisans and craftsmen, such as millwrights, clockmakers, instrument makers and surveyors. aside from these professions, universities were not believed to have had much practical significance to technology. : 32 a standard reference for the state of mechanical arts during the renaissance is given in the mining engineering treatise de re metallica ( 1556 ), which also contains sections on geology, mining, and chemistry. de re metallica
|
https://en.wikipedia.org/wiki/Engineering
|
the density matrix of composite spin system is discussed in relation to the adjoint representation of unitary group u ( n ). the entanglement structure is introduced as an additional ingredient to the description of the linear space carrying the adjoint representation. positive maps of density operator are related to random matrices. the tomographic probability description of quantum states is used to formulate the problem of separability and entanglement as the condition for joint probability distribution of several random variables represented as the convex sum of products of probabilities of random variables describing the subsystems. the property is discussed as a possible criterion for separability or entanglement. the convenient criterion of positivity of finite and infinite matrix is obtained. the u ( n ) - tomogram of a multiparticle spin state is introduced. the entanglement measure is considered in terms of this tomogram.
|
arxiv:quant-ph/0310022
|
it is shown that 3d vector van der waals ( conformal ) nonlinear $ \ sigma $ - model ( nsm ) on a sphere $ s ^ 2 $ has two types of topological excitations reminiscent vortices and instantons of 2d nsm. the first, the hedgehogs, are described by homotopic group $ \ pi _ 2 ( s ^ 2 ) = \ mathbb { z } $ and have the logarithmic energies. they are an analog of 2d vortices. the energy and interaction of these excitations are found. the second, corresponding to 2d instantons, are described by hpmotopic group $ \ pi _ 3 ( s ^ 2 ) = \ mathbb { z } $ or the hopf invariant $ h \ in \ mathbb { z } $. a possibility of the topological phase transition in this model and its applications are briefly discussed.
|
arxiv:hep-th/0002041
|
we present a detailed magnetothermal study of pr ( 0. 7 ) ca ( 0. 3 ) mno ( 3 ), a perovskite manganite in which an insulator - metal transition can be driven by magnetic field, but also by pressure, visible light, x - rays, or high currents. we find that the field - induced transition is associated with an enormous release of energy which accounts for its strong irreversibility. in the ferromagnetic metallic state, specific heat and magnetization measurements indicate a much smaller spin wave stiffness than that seen in any other manganite, which we attribute to spin waves among the ferromagnetically ordered pr moments. the coupling between the pr and mn spins may also provide a basis for understanding the low temperature phase diagram of this most unusual manganite.
|
arxiv:cond-mat/0001065
|
we present new and archival chandra x - ray observatory observations of x - shaped radio galaxies within z < 0. 1 alongside a comparison sample of normal double - lobed fr i and ii radio galaxies. by fitting elliptical distributions to the observed diffuse hot x - ray emitting atmospheres, we find that the ellipticity and the position angle of the hot gas follows that of the stellar light distribution for radio galaxy hosts in general. moreover, compared to the control sample, we find a strong tendency for x - shaped morphology to be associated with wings directed along the minor axis of the hot gas distribution. taken at face value, this result favors the hydrodynamic backflow models for the formation of x - shaped radio galaxies which naturally explain the geometry ; the merger - induced rapid reorientation models make no obvious prediction about orientation.
|
arxiv:0912.3001
|
calculating the true stress - strain curve for further analyzing the behavior of materials in sudden environment. 4 ) a graphical method, so - called " considere construction ", can help determine the behavior of stress - strain curve whether necking or drawing happens on the sample. by setting λ = l / l 0 { \ displaystyle \ lambda = l / l _ { 0 } } as determinant, the true stress and strain can be expressed with engineering stress and strain as below : σ t = σ e × λ, ε t = ln λ. { \ displaystyle \ sigma _ { t } = \ sigma _ { e } \ times \ lambda, \ qquad \ varepsilon _ { t } = \ ln \ lambda. } therefore, the value of engineering stress can be expressed by the secant line from made by true stress and λ { \ displaystyle \ lambda } value where λ = 0 { \ displaystyle \ lambda = 0 } to λ = 1 { \ displaystyle \ lambda = 1 }. by analyzing the shape of σ t − λ { \ displaystyle \ sigma _ { t } - \ lambda } diagram and secant line, we can determine whether the materials show drawing or necking. on the figure ( a ), there is only concave upward considere plot. it indicates that there is no yield drop so the material will be suffered from fracture before it yields. on the figure ( b ), there is specific point where the tangent matches with secant line at point where λ = λ y { \ displaystyle \ lambda = \ lambda _ { y } }. after this value, the slope becomes smaller than the secant line where necking starts to appear. on the figure ( c ), there is point where yielding starts to appear but when λ = λ d { \ displaystyle \ lambda = \ lambda _ { d } }, the drawing happens. after drawing, all the material will stretch and eventually show fracture. between λ y { \ displaystyle \ lambda _ { y } } and λ d { \ displaystyle \ lambda _ { d } }, the material itself does not stretch but rather, only the neck starts to stretch out. = = misconceptions = = a popular misconception is that all materials that bend are " weak " and those that do not are " strong ". in reality, many materials that undergo large elastic and plastic deformations, such as steel, are able to absorb stresses that would cause brittle materials,
|
https://en.wikipedia.org/wiki/Deformation_(engineering)
|
a fundamental assumption of reinforcement learning in markov decision processes ( mdps ) is that the relevant decision process is, in fact, markov. however, when mdps have rich observations, agents typically learn by way of an abstract state representation, and such representations are not guaranteed to preserve the markov property. we introduce a novel set of conditions and prove that they are sufficient for learning a markov abstract state representation. we then describe a practical training procedure that combines inverse model estimation and temporal contrastive learning to learn an abstraction that approximately satisfies these conditions. our novel training objective is compatible with both online and offline training : it does not require a reward signal, but agents can capitalize on reward information when available. we empirically evaluate our approach on a visual gridworld domain and a set of continuous control benchmarks. our approach learns representations that capture the underlying structure of the domain and lead to improved sample efficiency over state - of - the - art deep reinforcement learning with visual features - - often matching or exceeding the performance achieved with hand - designed compact state information.
|
arxiv:2106.04379
|
as a distributed learning, federated learning ( fl ) faces two challenges : the unbalanced distribution of training data among participants, and the model attack by byzantine nodes. in this paper, we consider the long - tailed distribution with the presence of byzantine nodes in the fl scenario. a novel two - layer aggregation method is proposed for the rejection of malicious models and the advisable selection of valuable models containing tail class data information. we introduce the concept of think tank to leverage the wisdom of all participants. preliminary experiments validate that the think tank can make effective model selections for global aggregation.
|
arxiv:2307.08324
|
the purpose of this paper is to study the derived category of simplicial multicategories with arbitrary sets of objects ( also known as, colored operads in simplicial sets ). our main result is a derived morita theory for operads - where we describe the derived mapping spaces between two multicategories p and q in terms of the nerve of a certain category of p - q - bimodules. as an application, we show that the derived category possesses internal hom - objects.
|
arxiv:1111.3904
|
betting and gaming, sport results, monitoring consoles, and sensor network monitoring. = = examples = = = = = web push = = = the web push proposal of the internet engineering task force is a simple protocol using http version 2 to deliver real - time events, such as incoming calls or messages, which can be delivered ( or " pushed " ) in a timely fashion. the protocol consolidates all real - time events into a single session which ensures more efficient use of network and radio resources. a single service consolidates all events, distributing those events to applications as they arrive. this requires just one session, avoiding duplicated overhead costs. web notifications are part of the w3c standard and define an api for end - user notifications. a notification allows alerting the user of an event, such as the delivery of an email, outside the context of a web page. as part of this standard, push api is fully implemented in chrome, firefox, and edge, and partially implemented in safari as of february 2023. = = = http server push = = = http server push ( also known as http streaming ) is a mechanism for sending unsolicited ( asynchronous ) data from a web server to a web browser. http server push can be achieved through any of several mechanisms. as a part of html5 the web socket api allows a web server and client to communicate over a full - duplex tcp connection. generally, the web server does not terminate a connection after response data has been served to a client. the web server leaves the connection open so that if an event occurs ( for example, a change in internal data which needs to be reported to one or multiple clients ), it can be sent out immediately ; otherwise, the event would have to be queued until the client ' s next request is received. most web servers offer this functionality via cgi ( e. g., non - parsed headers scripts on apache http server ). the underlying mechanism for this approach is chunked transfer encoding. another mechanism is related to a special mime type called multipart / x - mixed - replace, which was introduced by netscape in 1995. web browsers interpret this as a document that changes whenever the server pushes a new version to the client. it is still supported by firefox, opera, and safari today, but it is ignored by internet explorer and is only partially supported by chrome. it can be applied to html documents, and also for streaming images in webcam
|
https://en.wikipedia.org/wiki/Push_technology
|
we extend several classical eigenvalue estimates for dirac operators on compact manifolds to noncompact, even incomplete manifolds. this includes friedrich ' s estimate for manifolds with positive scalar curvature as well as the author ' s estimate on surfaces.
|
arxiv:0810.5598
|
using the uves echelle spectrograph at the eso vlt we obtained two - dimensional high - resolution ( r = 50 000 ) spectra of the edge - on disk objects hh30 *, hk tau b, and hv tau c. for comparison purposes we also observed with the same equipment both the classical t tauri star hl tau and the active late - type star ldn 1551 - 9. the spectra of all three observed edge - on disks consist of a t tauri emission and absorption line spectrum with superimposed jet emission lines. analysis of the spectra confirmed that the disks are completely opaque at visible wavelengths and that light from the central objects reaches us only via scattering layers above and below the disk planes. the central objects of our targets were found to be normal t tauri stars showing moderate but different amounts of veiling of their photospheric spectra, indicating different accretion rates or evolutionary stages. we suggest that all classical t tauri stars ( cttss ) show this observed morphology when viewed edge - on. part of the jet emission from edge - on systems is directly visible to us in the forbidden lines as well as in halpha and he i, a finding which contradicts the present paradigm of a pure magnetospheric accretion origin for the formation of hydrogen and helium emission lines in moderately active cttss. from a comparison with those taurus - auriga cttss for which the inclination is reliably known, we conclude that the view angle of ctts systems is one of the key parameters governing apparent halpha emission strength in the t tauri class. we discuss the various possible formation regions for the na i d lines and show that profiles similar to observed ones can be formed at the base of the disk wind.
|
arxiv:astro-ph/0501582
|
this white paper presents our work on surveylm, a platform for analyzing augmented language models ' ( alms ) emergent alignment behaviors through their dynamically evolving attitude and value perspectives in complex social contexts. social artificial intelligence ( ai ) systems, like alms, often function within nuanced social scenarios where there is no singular correct response, or where an answer is heavily dependent on contextual factors, thus necessitating an in - depth understanding of their alignment dynamics. to address this, we apply survey and experimental methodologies, traditionally used in studying social behaviors, to evaluate alms systematically, thus providing unprecedented insights into their alignment and emergent behaviors. moreover, the surveylm platform leverages the alms ' own feedback to enhance survey and experiment designs, exploiting an underutilized aspect of alms, which accelerates the development and testing of high - quality survey frameworks while conserving resources. through surveylm, we aim to shed light on factors influencing alms ' emergent behaviors, facilitate their alignment with human intentions and expectations, and thereby contributed to the responsible development and deployment of advanced social ai systems. this white paper underscores the platform ' s potential to deliver robust results, highlighting its significance to alignment research and its implications for future social ai systems.
|
arxiv:2308.00521
|
educational technology ( commonly abbreviated as edutech, or edtech ) is the combined use of computer hardware, software, and educational theory and practice to facilitate learning and teaching. when referred to with its abbreviation, " edtech ", it often refers to the industry of companies that create educational technology. in edtech inc. : selling, automating and globalizing higher education in the digital age, tanner mirrlees and shahid alvi ( 2019 ) argue " edtech is no exception to industry ownership and market rules " and " define the edtech industries as all the privately owned companies currently involved in the financing, production and distribution of commercial hardware, software, cultural goods, services and platforms for the educational market with the goal of turning a profit. many of these companies are us - based and rapidly expanding into educational markets across north america, and increasingly growing all over the world. " in addition to the practical educational experience, educational technology is based on theoretical knowledge from various disciplines such as communication, education, psychology, sociology, artificial intelligence, and computer science. it encompasses several domains including learning theory, computer - based training, online learning, and m - learning where mobile technologies are used. = = definition = = the association for educational communications and technology ( aect ) has defined educational technology as " the study and ethical practice of facilitating learning and improving performance by creating, using and managing appropriate technological processes and resources ". it denotes instructional technology as " the theory and practice of design, development, utilization, management, and evaluation of processes and resources for learning ". as such, educational technology refers to all valid and reliable applied education sciences, such as equipment, as well as processes and procedures that are derived from scientific research, and in a given context may refer to theoretical, algorithmic or heuristic processes : it does not necessarily imply physical technology. educational technology is the process of integrating technology into education in a positive manner that promotes a more diverse learning environment and a way for students to learn how to use technology as well as their common assignments. accordingly, there are several discrete aspects to describing the intellectual and technical development of educational technology : educational technology as the theory and practice of educational approaches to learning. educational technology as technological tools and media, for instance massive online courses, that assist in the communication of knowledge, and its development and exchange. this is usually what people are referring to when they use the term " edtech ". educational technology for learning management systems ( lms ), such as tools for student and curriculum management, and education
|
https://en.wikipedia.org/wiki/Educational_technology
|
natural language processing ( nlp ) has recently gained wide attention in cybersecurity, particularly in cyber threat intelligence ( cti ) and cyber automation. increased connection and automation have revolutionized the world ' s economic and cultural infrastructures, while they have introduced risks in terms of cyber attacks. cti is information that helps cybersecurity analysts make intelligent security decisions, that is often delivered in the form of natural language text, which must be transformed to machine readable format through an automated procedure before it can be used for automated security measures. this paper proposes securebert, a cybersecurity language model capable of capturing text connotations in cybersecurity text ( e. g., cti ) and therefore successful in automation for many critical cybersecurity tasks that would otherwise rely on human expertise and time - consuming manual efforts. securebert has been trained using a large corpus of cybersecurity text. to make securebert effective not just in retaining general english understanding, but also when applied to text with cybersecurity implications, we developed a customized tokenizer as well as a method to alter pre - trained weights. the securebert is evaluated using the standard masked language model ( mlm ) test as well as two additional standard nlp tasks. our evaluation studies show that securebert \ footnote { \ url { https : / / github. com / ehsanaghaei / securebert } } outperforms existing similar models, confirming its capability for solving crucial nlp tasks in cybersecurity.
|
arxiv:2204.02685
|
road accidents have a high societal cost that could be reduced through improved risk predictions using machine learning. this study investigates whether telemetric data collected on long - distance trucks can be used to predict the risk of accidents associated with a driver. we use a dataset provided by a truck transportation company containing the driving data of 1, 141 drivers for 18 months. we evaluate two different machine learning approaches to perform this task. in the first approach, features are extracted from the time series data using the fresh algorithm and then used to estimate the risk using random forests. in the second approach, we use a convolutional neural network to directly estimate the risk from the time - series data. we find that neither approach is able to successfully estimate the risk of accidents on this dataset, in spite of many methodological attempts. we discuss the difficulties of using telemetric data for the estimation of the risk of accidents that could explain this negative result.
|
arxiv:2007.09167
|
we give an overview of different approaches to measuring the similarity of, or the distance between, two graphs, highlighting connections between these approaches. we also discuss the complexity of computing the distances.
|
arxiv:2411.10182
|
we explore the possible enhancement of direct cp violating parameter epsilon ' / epsilon in the general left - right model based on the su ( 2 ) _ l times su ( 2 ) _ r times u ( 1 ) gauge group. the mixing matrix of right - handed quarks, v _ { ckm } ^ r is observable in the left - right model, and provides new source of cp violating phase. we calculate the parameter epsilon ' / epsilon in the left - right model and show that the new phases from v _ { ckm } ^ r can yield the sizable contribution to the direct cp violation enough to satisfy the recent measurements of re ( epsilon ' / epsilon ) from fermilab ktev and cern na48 experiments.
|
arxiv:hep-ph/0010107
|
we obtain age estimates for the progenitor ( s ) of the extremely metal - poor ( [ fe / h = - 2. 9 ) halo star cs 31082 - 001, based on the recently reported first observation of a uranium abundance in this ( or any other ) star. age estimates are derived by application of the classical r - process model with updated nuclear physics inputs. the [ u / th ] ratio yields an age of 13 + - 4 gyr or 8 + - 4 gyr, based on the use of the etfsi - q or the new hfbcs - 1 nuclear mass models, respectively. implications for thorium chronometers are discussed.
|
arxiv:astro-ph/0104335
|
we present a reanalysis of gw151226, the second binary black hole merger discovered by the ligo - - virgo collaboration. previous analysis showed that the best - fit waveform for this event corresponded to the merger of a $ \ sim 14 \, m _ \ odot $ black hole with a $ \ sim 7. 5 \, m _ \ odot $ companion, and the posterior distribution in mass ratio ( $ q \ leq 1 $ ) is rather flat. in this work, we perform parameter estimation using a waveform model that includes the effects of orbital precession and higher - order radiative multipole modes, and we find that the source parameters of gw151226 shift towards the low $ q $ and high effective spin ( $ \ chi _ { \ rm eff } $ ) region and that $ q $ is better measured. the new solution has a log likelihood roughly two points higher than when either higher multipoles or orbital precession is neglected and can alter the astrophysical interpretation of gw151226. additionally, we find it useful to use a flat - in - $ \ chi { \ rm eff } $ prior, which does not penalize the large $ | \ chi _ { \ rm eff } | $ region, in order to uncover the higher likelihood region for gw151226. our solution has several interesting properties : ( a ) the secondary black hole mass is close to the upper limit of the hypothesized lower mass gap of astrophysical black hole population ; and ( b ) orbital precession is driven by the primary black hole spin, which has a dimensionless magnitude as large as $ \ sim 0. 85 $ and is tilted away from the orbital angular momentum at an angle of $ \ sim 57 ^ \ circ $. since gw151226 is a relatively weak signal, an unambiguous claim of the detection of these effects in the signal cannot be made.
|
arxiv:2105.06486
|
in a recent paper, eichmair, galloway and pollack have proved a gannon - lee - type singularity theorem based on the existence of marginally outer trapped surfaces ( mots ) on noncompact initial data sets for globally hyperbolic spacetimes. this result requires that the mots be generic in a suitable sense. in the same spirit, this author has proven some variants of that result which hold for weaker causal conditions on spacetime, but which concern ( generic ) marginally trapped surfaces ( mts ) rather than mots, i. e., most of the results need a condition on the convergence of the ingoing family of normal null geodesics as well. however, much of the more recent literature has focused on mots rather than mts as quasi - local substitutes for the description of black holes, as they are arguably more natural and easier to handle in a number of situations. it is therefore pertinent to ask to what extent one can deduce the existence of singularities in the presence of mots alone. in this note, we address this issue and show that singularities still arise in the presence of generic mots under weaker causal conditions ( specifically, for causally simple spacetimes ). moreover, provided we assume that the mots is the boundary of a compact spatial region, a penrose - hawking - type singularity theorem can be established for chronological spacetimes containing generic mots.
|
arxiv:1207.1113
|
a fundamental problem in quantum physics is to encode functions that are completely anti - symmetric under permutations of identical particles. the barron space consists of high - dimensional functions that can be parameterized by infinite neural networks with one hidden layer. by explicitly encoding the anti - symmetric structure, we prove that the anti - symmetric functions which belong to the barron space can be efficiently approximated with sums of determinants. this yields a factorial improvement in complexity compared to the standard representation in the barron space and provides a theoretical explanation for the effectiveness of determinant - based architectures in ab - initio quantum chemistry.
|
arxiv:2303.12856
|
a general class, introduced in [ ekeland et al. 2003 ], of continuous time bond markets driven by a standard cylindrical brownian motion $ \ wienerq { } { } $ in $ \ ell ^ { 2 }, $ is considered. we prove that there always exist non - hedgeable random variables in the space $ \ derprod { } { 0 } = \ cap _ { p \ geq 1 } l ^ { p } $ and that $ \ derprod { } { 0 } $ has a dense subset of attainable elements, if the volatility operator is non - degenerated a. e. such results were proved in [ bj \ " ork et al. 1997 ] in the case of a bond market driven by finite dimensional b. m. and marked point processes. we define certain smaller spaces $ \ derprod { } { s }, $ $ s > 0 $ of european contingent claims, by requiring that the integrand in the martingale representation, with respect to $ \ wienerq { } { } $, takes values in weighted $ \ ell ^ { 2 } $ spaces $ \ ell ^ { s, 2 }, $ with a power weight of degree $ s. $ for all $ s > 0, $ the space $ \ derprod { } { s } $ is dense in $ \ derprod { } { 0 } $ and is independent of the particular bond price and volatility operator processes. a simple condition in terms of $ \ ell ^ { s, 2 } $ norms is given on the volatility operator processes, which implies if satisfied, that every element in $ \ derprod { } { s } $ is attainable. in this context a related problem of optimal portfolios of zero coupon bonds is solved for general utility functions and volatility operator processes, provided that the $ \ ell ^ { 2 } $ - valued market price of risk process has certain malliavin differentiability properties.
|
arxiv:math/0402364
|
we prove uniqueness of the kerr black holes within the connected, non - degenerate, analytic class of regular vacuum black holes.
|
arxiv:0806.0016
|
distributions sensitive to the underlying event in qcd jet events have been measured with the atlas detector at the lhc, based on 37 / pb of proton - proton collision data collected at a centre - of - mass energy of 7 tev. charged - particle mean $ p _ t $ and densities of all - particle $ e _ t $ and charged - particle multiplicity and $ p _ t $ have been measured in regions azimuthally transverse to the hardest jet in each event. these are presented both as one - dimensional distributions and with their mean values as functions of the leading - jet transverse momentum from 20 gev to 800 gev. the correlation of charged - particle mean $ p _ t $ with charged - particle multiplicity is also studied, and the $ e _ t $ densities include the forward rapidity region ; these features provide extra data constraints for monte carlo modelling of colour reconnection and beam - remnant effects respectively. for the first time, underlying event observables have been computed separately for inclusive jet and exclusive dijet event selections, allowing more detailed study of the interplay of multiple partonic scattering and qcd radiation contributions to the underlying event. comparisons to the predictions of different monte carlo models show a need for further model tuning, but the standard approach is found to generally reproduce the features of the underlying event in both types of event selection.
|
arxiv:1406.0392
|
collaborative filtering ( cf ) is a widely studied research topic in recommender systems. the learning of a cf model generally depends on three major components, namely interaction encoder, loss function, and negative sampling. while many existing studies focus on the design of more powerful interaction encoders, the impacts of loss functions and negative sampling ratios have not yet been well explored. in this work, we show that the choice of loss function as well as negative sampling ratio is equivalently important. more specifically, we propose the cosine contrastive loss ( ccl ) and further incorporate it to a simple unified cf model, dubbed simplex. extensive experiments have been conducted on 11 benchmark datasets and compared with 29 existing cf models in total. surprisingly, the results show that, under our ccl loss and a large negative sampling ratio, simplex can surpass most sophisticated state - of - the - art models by a large margin ( e. g., max 48. 5 % improvement in ndcg @ 20 over lightgcn ). we believe that simplex could not only serve as a simple strong baseline to foster future research on cf, but also shed light on the potential research direction towards improving loss function and negative sampling. our source code will be available at https : / / reczoo. github. io / simplex.
|
arxiv:2109.12613
|
we derived one - fluid equations based on a relativistic two - fluid approximation of e $ ^ \ pm $ pair plasma and electron - ion plasma to reveal the specific relativistic nature of their behavior. assuming simple condition on the relativistic one - fluid equations, we propose generalized relativistic magnetohydrodynamic ( rmhd ) equations which satisfy causality. we show the linear analyses of these equations regarding various plasma waves to show the validity of the generalized rmhd equations derived here and to reveal the distinct properties of the pair plasma and electron - ion plasma. the distinct properties relate to ( i ) the inertia effect of electric charge, ( ii ) the momentum of electric current, ( iii ) the relativistic hall effect, ( iv ) the thermal electromotive force, and ( v ) the thermalized energy exchange between the two fluids. using the generalized rmhd equations, we also clarify the condition that we can use standard rmhd equations and that we need the distinct rmhd equations of pair and electron - ion plasmas. the standard rmhd is available only when the relative velocity of the two fluids is nonrelativistic, a difference of the enthalpy densities of the two fluids is much smaller than the total enthalpy density, and the above distinct properties of the pair / electron - ion plasma are negligible. we discuss a general relativistic version of the equations applicable to the pair and electron - ion plasmas in black hole magnetospheres. we find the effective resistivity due to shear of frame ragging around a rotating black hole.
|
arxiv:0902.4292
|
we report high - resolution spin - resolved photoemission spectroscopy ( spin - arpes ) measurements on the parent compound sb of the recently discovered 3d topological insulator bi1 - xsbx [ d. hsieh et al., nature 452, 970 ( 2008 ) ]. by modulating the incident photon energy, we are able to map both the bulk and ( 111 ) surface band structure, from which we directly demonstrate that the surface bands are spin polarized by the spin - orbit interaction and connect the bulk valence and conduction bands in a topologically non - trivial way. a unique asymmetric dirac surface state gives rise to a k - splitting of its spin polarized electronic channels. these results complement our previously published works on this materials class and re - confirm our discovery of topological insulator states in the bi - sb series.
|
arxiv:1001.1574
|
let k, k ' be convex cones residing in finite - dimensional real vector spaces e, e '. an element in the tensor product e \ otimes e ' is k \ otimes k ' - separable if it can be represented as finite sum \ sum _ l x _ l \ otimes x ' _ l with x _ l \ in k and x _ l ' \ in k ' for all l. let s ( n ), h ( n ), q ( n ) be the spaces of n x n real symmetric, complex hermitian and quaternionic hermitian matrices, respectively. let further s _ + ( n ), h _ + ( n ), q _ + ( n ) be the cones of positive semidefinite matrices in these spaces. if a matrix in h ( mn ) = h ( m ) \ otimes h ( n ) is h _ + ( m ) \ otimes h _ + ( n ) - separable, then it fulfills also the so - called ppt condition, i. e. it is positive semidefinite and has a positive semidefinite partial transpose. the same implication holds for matrices in the spaces s ( m ) \ otimes s ( n ), h ( m ) \ otimes s ( n ), and for m < 3 in the space q ( m ) \ otimes s ( n ). we provide a complete enumeration of all pairs ( n, m ) when the inverse implication is also true for each of the above spaces, i. e. the ppt condition is sufficient for separability. we also show that a matrix in q ( n ) \ otimes s ( 2 ) is q _ + ( n ) \ otimes s _ + ( 2 ) - separable if and only if it is positive semidefinite.
|
arxiv:math/0701571
|
this paper is devoted to the study of phase transitions associated to a large family of gagliardo - nirenberg - sobolev interpolation inequalities on the sphere depending on one parameter. we characterize symmetry and symmetry breaking regimes, with a phase transition that can be of first or second order. we establish various new results and study the qualitative properties of the branches of solutions to the euler - lagrange equations.
|
arxiv:2210.16878
|
m dwarf stars provide us with an ideal opportunity to study nearby small planets. the humdrum ( hunting for m dwarf rocky planets using maroon - x ) survey uses the maroon - x spectrograph, which is ideally suited to studying these stars, to measure precise masses of a volume - limited ( $ < \, 30 $ pc ) sample of transiting m dwarf planets. toi - 1450 is a nearby ( 22. 5 pc ) binary system containing a m3 dwarf with a roughly 3000 k companion. its primary star, toi - 1450a, was identified by $ tess $ to have a 2. 04d transit signal, and is included in the humdrum sample. in this paper, we present maroon - x radial velocities which confirm the planetary nature of this signal and measure its mass at a nearly 10 % precision. the 2. 04d planet, toi - 1450ab, has $ r _ b \, = \, 1. 13 \, \ pm \, 0. 04 \, r _ \ oplus $ and $ m _ b \, = \, 1. 26 \, \ pm \, 0. 13 \, m _ \ oplus $. it is the second - lowest - mass transiting planet with a high - precision rv mass measurement. with this mass and radius, the planet ' s mean density is compatible with an earth - like composition. given its short orbital period and slightly sub - earth density, it may be amenable to $ jwst $ follow - up to test whether the planet has retained an atmosphere despite extreme heating from the nearby star. we also discover a non - transiting planet in the system with a period of 5. 07 days and a $ m \ mathrm { sin } i _ c \, = \, 1. 53 \, \ pm \, 0. 18 \, m _ \ oplus $. we also find a 2. 01d signal present in the systems ' s $ tess $ photometry that likely corresponds to the rotation period of toi - 1450a ' s binary companion, toi - 1450b. toi - 1450a, meanwhile, appears to have a rotation period of approximately 40 days, which is in - line with our expectations for a mid - m dwarf.
|
arxiv:2405.10400
|
the aim of this note is to prove by a perturbation method the existence of solutions of the coupled einstein - dirac - maxwell equations for a static, spherically symmetric system of two fermions in a singlet spinor state and with the electromagnetic coupling constant $ ( \ frac { e } { m } ) ^ 2 < 1 $. we show that the nondegenerate solution of choquard ' s equation generates a branch of solutions of the einstein - dirac - maxwell equations.
|
arxiv:0912.4246
|
diffusion on complex networks is often modeled as a stochastic process. yet, recent work on strategic diffusion emphasizes the decision power of agents and treats diffusion as a strategic problem. here we study the computational aspects of strategic diffusion, i. e., finding the optimal sequence of nodes to activate a network in the minimum time. we prove that finding an optimal solution to this problem is np - complete in a general case. to overcome this computational difficulty, we present an algorithm to compute an optimal solution based on a dynamic programming technique. we also show that the problem is fixed parameter - tractable when parametrized by the product of the treewidth and maximum degree. we analyze the possibility of developing an efficient approximation algorithm and show that two heuristic algorithms proposed so far cannot have better than a logarithmic approximation guarantee. finally, we prove that the problem does not admit better than a logarithmic approximation, unless p = np.
|
arxiv:1809.03141
|
the first collisions of lead nuclei, delivered by the cern large hadron collider ( lhc ) at the end of 2010, at a centre - of - mass energy per nucleon pair $ \ sqrt { s _ { nn } } $ = 2. 76 tev, marked the beginning of a new era in ultra - relativistic heavy - ion physics. following the run 1 period, lhc also successfully delivered pbpb collisions at the collision energy $ \ sqrt { s _ { nn } } $ = 5. 02 tev at the end of 2015. the study of the properties of the produced hot and dense strongly - interacting matter at these unprecedented energies is experimentally pursued by all four big lhc experiments, alice, atlas, cms, and lhcb. this review presents selected experimental results from heavy - ion collisions delivered during the first three years of the lhc operation focusing on the bulk matter properties and the dynamical evolution of the created system. it also presents the first results from run 2 heavy - ion data at the highest energy, as well as from the studies of the reference pp and ppb systems, which are an integral part of the heavy - ion programme.
|
arxiv:1702.07233
|
large language models ( llms ) have demonstrated the strong potential to assist both clinicians and the general public with their extensive medical knowledge. however, their application in healthcare is constrained due to concerns about the privacy of data used in training, which prevents the integration of private and personal information because of security and ethical issues. moreover, if their capabilities can be enhanced with information retrieval to access up - to - date knowledge, the current integration of llms with information retrieval lacks robustness to imperfect retrieval, which can hinder their effectiveness and even reduce overall performance. in this work, we address this challenge by introducing the retrieval - augmented thought process ( ratp ). given access to external knowledge, ratp formulates the thought generation of llms as a multiple - step decision process. to optimise such a thought process, ratp leverages monte - carlo tree search and learns a proxy reward function that permits cost - efficient inference. on a private dataset of electronic medical records, deliberately excluded from any llm training set, ratp achieves 35 % additional accuracy compared to in - context retrieval - augmented generation for the question - answering task.
|
arxiv:2402.07812
|
in this article, we prove that the average rank of elliptic curves over $ \ mathbb { q } $, when ordered by height, is less than $ 1 $ ( in fact, less than $. 885 $ ). as a consequence of our methods, we also prove that at least four fifths of all elliptic curves over $ \ mathbb { q } $ have rank either 0 or 1 ; furthermore, at least one fifth of all elliptic curves in fact have rank 0. the primary ingredient in the proofs of these theorems is a determination of the average size of the $ 5 $ - selmer group of elliptic curves over $ \ mathbb { q } $ ; we prove that this average size is $ 6 $. another key ingredient is a new lower bound on the equidistribution of root numbers of elliptic curves ; we prove that there is a family of elliptic curves over $ \ mathbb { q } $ having density at least $ 55 \ % $ for which the root number is equidistributed.
|
arxiv:1312.7859
|
the property and casualty ( p & c ) insurance industry faces challenges in developing claim predictive models due to the highly right - skewed distribution of positive claims with excess zeros. to address this, actuarial science researchers have employed " zero - inflated " models that combine a traditional count model and a binary model. this paper investigates the use of boosting algorithms to process insurance claim data, including zero - inflated telematics data, to construct claim frequency models. three popular gradient boosting libraries - xgboost, lightgbm, and catboost - are evaluated and compared to determine the most suitable library for training insurance claim data and fitting actuarial frequency models. through a comprehensive analysis of two distinct datasets, it is determined that catboost is the best for developing auto claim frequency models based on predictive performance. furthermore, we propose a new zero - inflated poisson boosted tree model, with variation in the assumption about the relationship between inflation probability $ p $ and distribution mean $ \ mu $, and find that it outperforms others depending on data characteristics. this model enables us to take advantage of particular catboost tools, which makes it easier and more convenient to investigate the effects and interactions of various risk features on the frequency model when using telematics data.
|
arxiv:2307.07771
|
given a pair of real functions $ ( k, f ) $, we study the conditions they must satisfy for $ k + \ lambda f $ to be the curvature in the arc - length of a closed planar curve for all real $ \ lambda $. several equivalent conditions are pointed out, certain periodic behaviours are shown as essential and a family of such pairs is explicitely constructed. the discrete counterpart of the problem is also studied. finally, the characterization obtained is used to show that a sufficient analogue of the 4 - vertex theorem cannot be developed.
|
arxiv:2006.09678
|
this is a survey of the use of fourier analysis in additive combinatorics, with a particular focus on situations where it cannot be straightforwardly applied, but needs to be generalized first. sometimes very satisfactory generalizations exist, while sometimes we have to make do with theories that have some of the desirable properties of fourier analysis but not all of them. in the latter case, there are intriguing hints that there may be more satisfactory theories yet to be discovered. this article grew out of the colloquium lectures at the joint meeting of the ams and the maa, given in seattle in january 2016.
|
arxiv:1608.04127
|
the extraction of wilson loops of confining gauge systems from their sugra ( string ) duals is reviewed. i start with describing the basic classical setup. a theorem that determines the classical values of the loops associated with a generalized background is derived. in particular sufficient conditions for confining behavior are stated. i then introduce quadratic quantum fluctuations around the classical configurations. i discuss in details the following models of confining behavior : ( i ) strings in flat space - time, ( ii ) $ ads _ 5 $ black hole and its correspondence with pure ym theory in three dimensions. in particular an attractive luscher term is shown to be the outcome of the quantum fluctuations. ( iii ) type 0 string model ( iv ) the polchinski strassler $ n = 1 * $ model. in the latter case we show that sugra alone is not enough to get the correct nature of the loops, and only by incorporating the worldvolume phenomena of the five branes a coherent qualitative picture can be derived.
|
arxiv:hep-th/0009146
|
we systematically explore a pathway for generating nonlinear charge and spin photocurrents using spin - orbit - split surface states. this mechanism enables net charge and spin flow along the surface plane even in centrosymmetric bulk environments like the rashba prototype au ( 111 ), where we establish the key principles by combining model predictions with density functional calculations. we further identify the tl / si ( 111 ) surface, characterized by strong non - rashba spin - orbit coupling, as a prime candidate for experimental validation ; with slight doping, it develops metallic spin - orbit - split states featuring remarkable relativistic properties while the bulk remains semiconducting. our non - linear simulations reveal distinct angular signatures and magnitudes comparable to bulk ferroelectrics, highlighting the potential of surface - state photocurrents for low - bias optoelectronic applications. moreover, the intricate spin polarization of surface states opens new possibilities as a nonlinear spin filter, providing a far more versatile platform than the spin hall effect.
|
arxiv:2503.14360
|
using the phase plane diagrams, the phase light curves of a group of the mira - type stars and semi - regular variables are analyzed. as generalized coordinates x and $ \ dot { x } $, we have used m - the brightness of the star and its phase derivative. we have used mean phase light curves using observations of various authors. the data typically span a large time interval ( nearly a century ). they were compiled from the databases of aavso, afoev, vsolj, asas and approximated using a trigonometric polynomial of statistically optimal degree. as the resulting approximation characterizes the auto - oscillation process, which leads to a photometrical variability, the phase diagram corresponds to a limit cycle. for all stars studied, the limit cycles were computed. for a simple sine - like light curve, in e. g., l $ _ 2 $ pup, the limit cycle is a simple ellipse. in a case of more complicated light curve, in which harmonics are statistically significant, the limit cycle has deviations from the ellipse. in an addition to a classical analysis, we use the error estimates of the smoothing function and its derivative to constrain an " error corridor " in the phase plane.
|
arxiv:1711.02133
|
current advances in natural language processing ( nlp ) have made it increasingly feasible to build applications leveraging textual data. generally, the core of these applications rely on having a good semantic representation of text into vectors, via embedding models. however, it has been shown that these embeddings capture and perpetuate biases already present in text. while a few techniques have been proposed to debias embeddings, they do not take advantage of the recent advances in context understanding of modern embedding models. in this paper, we fill this gap by conducting a review of 19 embedding models by quantifying their biases and how well they respond to context injection as a mean of debiasing. we show that higher performing models are more prone to capturing biases, but are also better at incorporating context. surprisingly, we find that while models can easily embed affirmative semantics, they fail at embedding neutral semantics. finally, in a retrieval task, we show that biases in embeddings can lead to non - desirable outcomes. we use our new - found insights to design a simple algorithm for top $ k $ retrieval, where $ k $ is dynamically selected. we show that our algorithm is able to retrieve all relevant gendered and neutral chunks.
|
arxiv:2410.12874
|
we present a new approach to conformance testing of black - box reactive systems. we consider system specifications written as linear temporal logic formulas to generate tests as sequences of input / output pairs : inputs are extracted from the buchi automata corresponding to the specifications, and outputs are obtained by feeding the inputs to the systems. conformance is checked by comparing input / output sequences with automata traces to detect violations of the specifications. we consider several criteria for extracting tests and for stopping generation, and we compare them experimentally using both indicators of coverage and error - detection. the results show that our methodology can generate test suites with good system coverage and error - detection capability.
|
arxiv:2005.06750
|
many problems such as node classification and link prediction in network data can be solved using graph embeddings. however, it is difficult to use graphs to capture non - binary relations such as communities of nodes. these kinds of complex relations are expressed more naturally as hypergraphs. while hypergraphs are a generalization of graphs, state - of - the - art graph embedding techniques are not adequate for solving prediction and classification tasks on large hypergraphs accurately in reasonable time. in this paper, we introduce hypernetvec, a novel hierarchical framework for scalable unsupervised hypergraph embedding. hypernetvec exploits shared - memory parallelism and is capable of generating high quality embeddings for real - world hypergraphs with millions of nodes and hyperedges in only a couple of minutes while existing hypergraph systems either fail for such large hypergraphs or may take days to produce the embeddings.
|
arxiv:2103.09660
|
the validity of semiclassical expansions in the power of $ \ hbar $ for the quantum green ' s function have been extensively tested for billiards systems, but in the case of chaotic dynamics with smooth potential, even if formula are existing, a quantitative comparison is still missing. in this paper, extending the theory developed by gaspard et al., adv. chem. phys. xc 105 ( 1995 ), based on the classical green ' s functions, we present an efficient method allowing the calculation of $ \ hbar $ corrections for the propagator, the quantum green ' s function, and their traces. especially, we show that the previously published expressions for $ \ hbar $ corrections to the traces are incomplete.
|
arxiv:nlin/0107031
|
elliptic integrals, since euler ' s finding of addition theorem 1751, has been studied extensively from various view points. present paper gives a view point from primitive integrals of types $ \ mathrm { a _ 2 }, \ mathrm { b _ 2 } $ and $ \ mathrm { g _ 2 } $ for the three families of elliptic curves of weierstrass, jacobi - legendre and hesse, respectively. we solve jacobi inversion problem for the period maps in the sense explained in the introduction ( see [ siegel ] chap. 1, 13 ) by introducing certain generalized eisenstein series of types $ \ mathrm { a _ 2 }, \ mathrm { b _ 2 } $ and $ \ mathrm { \ mathrm { g _ 2 } } $, which generate the ring of invariant functions on the period domain for the congruence subgroups $ \ gamma _ 1 ( n ) $ ( $ n = 1, 2 $ and $ 3 $ ). in particular, eisenstein series of type $ \ mathrm { b _ 2 } $ includes the case of weight two, and eisenstein series of type $ \ mathrm { g _ 2 } $ includes the cases of weight one and two, which seem to be of new feature. the goal of the paper is a partial answer to the discriminant conjecture, which claims an existence of certain cusp form of weight 1 with character of topological origin, giving a power root of the discriminant form ( aspects math., e36, p. \ 265 - 320. \ 2004 ). see \ s12 concluding remarks for more about back grounds of the present paper.
|
arxiv:1909.02715
|
scientific figure interpretation is a crucial capability for ai - driven scientific assistants built on advanced large vision language models. however, current datasets and benchmarks primarily focus on simple charts or other relatively straightforward figures from limited science domains. to address this gap, we present a comprehensive dataset compiled from peer - reviewed nature communications articles covering 72 scientific fields, encompassing complex visualizations such as schematic diagrams, microscopic images, and experimental data which require graduate - level expertise to interpret. we evaluated 19 proprietary and open - source models on two benchmark tasks, figure captioning and multiple - choice, and conducted human expert annotation. our analysis revealed significant task challenges and performance gaps among models. beyond serving as a benchmark, this dataset serves as a valuable resource for large - scale training. fine - tuning qwen2 - vl - 7b with our task - specific data achieved better performance than gpt - 4o and even human experts in multiple - choice evaluations. furthermore, continuous pre - training on our interleaved article and figure data substantially enhanced the model ' s downstream task performance in materials science. we have released our dataset to support further research.
|
arxiv:2407.04903
|
many real - world data sets are sparse or almost sparse. one method to measure this for a matrix $ a \ in \ mathbb { r } ^ { n \ times n } $ is the \ emph { numerical sparsity }, denoted $ \ mathsf { ns } ( a ) $, defined as the minimum $ k \ geq 1 $ such that $ \ | a \ | _ 1 / \ | a \ | _ 2 \ leq \ sqrt { k } $ for every row and every column $ a $ of $ a $. this measure of $ a $ is smooth and is clearly only smaller than the number of non - zeros in the row / column $ a $. the seminal work of achlioptas and mcsherry [ 2007 ] has put forward the question of approximating an input matrix $ a $ by entrywise sampling. more precisely, the goal is to quickly compute a sparse matrix $ \ tilde { a } $ satisfying $ \ | a - \ tilde { a } \ | _ 2 \ leq \ epsilon \ | a \ | _ 2 $ ( i. e., additive spectral approximation ) given an error parameter $ \ epsilon > 0 $. the known schemes sample and rescale a small fraction of entries from $ a $. we propose a scheme that sparsifies an almost - sparse matrix $ a $ - - it produces a matrix $ \ tilde { a } $ with $ o ( \ epsilon ^ { - 2 } \ mathsf { ns } ( a ) \ cdot n \ ln n ) $ non - zero entries with high probability. we also prove that this upper bound on $ \ mathsf { nnz } ( \ tilde { a } ) $ is \ emph { tight } up to logarithmic factors. moreover, our upper bound improves when the spectrum of $ a $ decays quickly ( roughly replacing $ n $ with the stable rank of $ a $ ). our scheme can be implemented in time $ o ( \ mathsf { nnz } ( a ) ) $ when $ \ | a \ | _ 2 $ is given. previously, a similar upper bound was obtained by achlioptas et. al [ 2013 ] but only for a restricted class of inputs that does not even include symmetric or covariance matrices. finally, we demonstrate two applications of these sampling techniques, to faster approximate matrix multiplication, and to ridge regression by using sparse preconditioners.
|
arxiv:2011.01777
|
the nro - ovro co imaging survey showed that molecular gas was more concentrated to the central kiloparsec in barred spiral galaxies than in their unbarred counterparts. the result provided not only evidence for bar - driven gas transport but also estimates on the mean rate of gas transfer and lower limits to the lifetime of bars. other lines of evidence for the bar - driven transport of ism in spiral galaxies are summarized. they are complementary with each other.
|
arxiv:astro-ph/9910226
|
over large timescales, a terrestrial planet may be driven towards spin - orbit synchronous rotation by tidal forces. in this particular configuration, the planet exhibits permanent dayside and nightside, which may induce strong day - night temperature gradients. the nightside temperature depends on the efficiency of the day - night heat redistribution and determines the stability of the atmosphere against collapse. to better constrain the atmospheric stability, climate, and surface conditions of rocky planets located in the habitable zone of their host star, it is thus crucial to understand the complex mechanism of heat redistribution. building on early works and assuming dry thermodynamics, we developed a hierarchy of analytic models taking into account the coupling between radiative transfer, dayside convection, and large - scale atmospheric circulation in the case of slowly rotating planets. there are two types of these models : a zero - dimensional two - layer approach and a two - column radiative - convective - subsiding - upwelling ( rcsu ) model. they yield analytical solutions and scaling laws characterising the dependence of the collapse pressure on physical features, which are compared to the results obtained by early works using 3d global climate models ( gcms ). the analytical theory captures ( i ) the dependence of temperatures on atmospheric opacities and scattering in the shortwave and in the longwave, ( ii ) the behaviour of the collapse pressure observed in gcm simulations at low stellar fluxes that are due to the non - linear dependence of the atmospheric opacity on the longwave optical depth at the planet ' s surface, ( iii ) the increase of stability generated by dayside sensible heating, and ( iv ) the decrease of stability induced by the increase of the planet size.
|
arxiv:2004.07134
|
exact numerical diagonalization of the bohr hamiltonian by su ( 1, 1 ) xso ( 5 ) methods is used to obtain detailed quantitative predictions for single - phonon and multi - phonon excitations in well - deformed rotor nuclei. dynamical gamma deformation is found to significantly influence the predictions through its coupling to the rotational motion. basic signatures for the onset of rigid triaxial deformation are obtained.
|
arxiv:0902.0022
|
dating to 1994, simon ' s period - finding algorithm is among the earliest and most fragile of quantum algorithms. the algorithm ' s fragility arises from the requirement that, to solve an n qubit problem, one must fault - tolerantly sample o ( n ) linearly independent values from a solution space. in this paper, we study an adiabatic implementation of simon ' s algorithm that requires a constant number of successful samples regardless of problem size. we implement this algorithm on d - wave hardware and solve problems with up to 298 qubits. we compare the runtime of classical algorithms to the d - wave solution to analyze any potential advantage.
|
arxiv:2504.10771
|
understanding stellar activity in m dwarfs is fundamental to improving our knowledge of the physics of stellar atmospheres and for planet search programmes. high levels of stellar activity ( also with flare events ) can cause additional variations in the stellar emission that contaminate the signal induced by a planet and that need to be corrected. the study of activity indicators in active stars can improve our capability of modelling this signal. our aim is to understand the behaviour of stellar chromospheres of m stars, studying the more sensitive chromospheric activity indicators, characterising their variability and on finding the correlations among these indicators to obtain information on the origin of the magnetic activity in low - mass stars. we studied the main optical activity indicators ( ca ii h & k, balmer lines, na i d $ _ { 1, 2 } $ doublet, he i d $ _ 3 $ and other helium lines ) measured for ad leonis using the data provided by harps - n in 2018 and by harps in 2006. we measured excess flux of the selected activity indicators and analysed the correlation between the different indicators as well as the temporal evolution of fluxes. a stellar flare was identified during the 2018 observing run and the h $ \ alpha $, h $ \ beta $, he i 4471 a and he i 5876 a lines were analysed in detail by fitting the line profiles with two gaussian components. we found that the ca ii h & k flux excesses are strongly correlated with each other, but the ca ii h & k doublet is generally less correlated with the other indicators. moreover, h $ \ alpha $ is correlated with na i doublet and helium lines. analysing the time variability of flux of the studied lines, we found a higher level of activity of the star during the observations in 2018 than in 2006, while ca ii h & k showed more intense emission on spectra obtained during the observations in 2006. we investigated the flare evaluating the mass motion during the event.
|
arxiv:2008.04242
|
the calculation of the two - loop corrections to the three jet production rate and to event shapes in electron - positron annihilation requires the computation of a number of up to now unknown two - loop four - point master integrals with one off - shell and three on - shell legs. in this paper, we compute those master integrals which correspond to planar topologies by solving differential equations in the external invariants which are fulfilled by the master integrals. we obtain the master integrals as expansions in $ \ e = ( 4 - d ) / 2 $, where $ d $ is the space - time dimension. the results are expressed in terms of newly introduced two - dimensional harmonic polylogarithms, whose properties are shortly discussed. for all two - dimensional harmonic polylogarithms appearing in the divergent parts of the integrals, expressions in terms of nielsen ' s polylogarithms are given. the analytic continuation of our results to other kinematical situations is outlined.
|
arxiv:hep-ph/0008287
|
a novel 4 - dimensional einstein - gauss - bonnet ( 4d egb ) gravity has been proposed that asserts to bypass the lovelock ' s theorem and to result in a non - trivial contribution to the gravitational dynamics in four - dimensional spacetime. in this work, we study the integrated sachs - wolfe ( isw ) effect in the 4d egb model. for this purpose, we calculate the evolution of the gravitational potential and the linear growth factor as a function of redshift for the 4d egb model and compare it with the corresponding result obtained from the $ \ lambda $ - cold dark matter ( $ \ lambda $ cdm ) model. we also calculate the isw - auto power spectrum and the isw - cross power spectrum as functions of cosmic microwave background ( cmb ) multipoles for the 4d egb model and compare those with the one obtained from the $ \ lambda $ cdm model. to do this, we use the strongest constraint on the coupling parameter proposed for the 4d egb model. additionally, to calculate the isw effect for the 4d egb model, we employ three large - scale structure surveys from different wavelengths. the results exhibit that the isw effect in the 4d egb model is higher than the one obtained from the $ \ lambda $ cdm model. hence, we show that the 4d egb model can amplify the amplitude of the isw power spectrum, which can be considered as a relative advantage of the 4d egb model comparing the $ \ lambda $ cdm one. also, we indicate that the deviation from the $ \ lambda $ cdm model is directly proportional to the value of the dimensionless coupling parameter $ \ beta $.
|
arxiv:2107.00562
|
public large - scale text - to - image diffusion models, such as stable diffusion, have gained significant attention from the community. these models can be easily customized for new concepts using low - rank adaptations ( loras ). however, the utilization of multiple concept loras to jointly support multiple customized concepts presents a challenge. we refer to this scenario as decentralized multi - concept customization, which involves single - client concept tuning and center - node concept fusion. in this paper, we propose a new framework called mix - of - show that addresses the challenges of decentralized multi - concept customization, including concept conflicts resulting from existing single - client lora tuning and identity loss during model fusion. mix - of - show adopts an embedding - decomposed lora ( ed - lora ) for single - client tuning and gradient fusion for the center node to preserve the in - domain essence of single concepts and support theoretically limitless concept fusion. additionally, we introduce regionally controllable sampling, which extends spatially controllable sampling ( e. g., controlnet and t2i - adaptor ) to address attribute binding and missing object problems in multi - concept sampling. extensive experiments demonstrate that mix - of - show is capable of composing multiple customized concepts with high fidelity, including characters, objects, and scenes.
|
arxiv:2305.18292
|
horv \ ' ath and kiss [ proc. amer. math. soc., 2005 ] proved the upper bound estimate $ \ frac { \ lambda _ { n } } { \ lambda _ { m } } \ leq \ frac { n ^ { 2 } } { m ^ { 2 } } $ $ ( n > m \ geq 1 ) $ for dirichlet eigenvalue ratios of the schr \ " odinger problem $ - y ' ' + q ( x ) y = \ lambda y $ with nonnegative and single - well potential $ q $. in this paper, we prove that if $ q ( x ) $ is a nonpositive, continuous and single - barrier potential, then $ \ frac { \ lambda _ { n } } { \ lambda _ { m } } \ geq \ frac { n ^ { 2 } } { m ^ { 2 } } $ for $ \ lambda _ n > \ lambda _ m \ geq - 2q ^ * $, where $ q ^ { \ ast } = \ min \ { q ( 0 ), q ( 1 ) \ } $. in particular, if $ q ( x ) $ satisfies the additional condition $ \ mid q ^ { \ ast } \ mid \ leq \ frac { \ pi ^ { 2 } } { 3 } $, then $ \ lambda _ { 1 } > 0 $ and $ \ frac { \ lambda _ { n } } { \ lambda _ { m } } \ geq \ frac { n ^ { 2 } % } { m ^ { 2 } } $ for $ n > m \ geq 1. $ for this result, we develop a new approach to study the monotonicity of the modified pr \ " ufer angle function.
|
arxiv:1504.00660
|
we develop a theory to describe the damping of elementary excitations of a bose - condensed gas in the hydrodynamic regime for the thermal cloud. we discuss second sound in a spatially homogeneous gas and the lowest excitations of a trapped condensate.
|
arxiv:cond-mat/9911238
|
regarding the strange properties of quantum entropy and entanglement, e. g., the negative quantum conditional entropy, we revisited the foundations of quantum entropy, namely, von neumann entropy, and raised the new method of quantum fine - grained entropy. with the applications in entanglement theory, quantum information processing, and quantum thermodynamics, we demonstrated the capability of quantum fine - grained entropy to resolve some notable confusions and problems, including the measure of entanglement and quantumness, the additivity conjecture of entanglement of formation etc, and the definition of temperature for single quantum system.
|
arxiv:1205.1235
|
a learning algorithm $ a $ trained on a dataset $ d $ is revealed to have poor performance on some subpopulation at test time. where should the responsibility for this lay? it can be argued that the data is responsible, if for example training $ a $ on a more representative dataset $ d ' $ would have improved the performance. but it can similarly be argued that $ a $ itself is at fault, if training a different variant $ a ' $ on the same dataset $ d $ would have improved performance. as ml becomes widespread and such failure cases more common, these types of questions are proving to be far from hypothetical. with this motivation in mind, in this work we provide a rigorous formulation of the joint credit assignment problem between a learning algorithm $ a $ and a dataset $ d $. we propose extended shapley as a principled framework for this problem, and experiment empirically with how it can be used to address questions of ml accountability.
|
arxiv:1910.04214
|
hadron production in lepton - nucleus deep inelastic scattering is studied in a model including quark energy loss and nuclear absorption. the leading - order computations for hadron multiplicity ratios are presented and compared with the selected hermes experimental data with the quark hadronization occurring inside the nucleus by means of the hadron formation time. it is shown that with increase of the energy fraction carried by the hadron, the nuclear suppression on hadron multiplicity ratio from nuclear absorption gets bigger. it is found that when hadronization occurs inside the nucleus, the nuclear absorption is the dominant mechanism causing a reduction of the hadron yield. the atomic mass dependence of hadron attenuation for quark hadronization starting inside the nucleus is confirmed theoretically and experimentally to be proportional to $ a ^ { 1 / 3 } $.
|
arxiv:1310.5285
|
practitioners and excommunicating members. the church ' s administration is headquartered on christian science center on the corner of massachusetts avenue and huntington avenue, located on several acres in the back bay section of boston. the 14. 5 - acre site includes the mother church ( 1894 ), mother church extension ( 1906 ), the christian science publishing society building ( 1934 ) — which houses the mary baker eddy library and the church ' s administrative staff — the sunday school building ( 1971 ), and the church colonnade building ( 1972 ). it also includes the 26 - story administration building ( 1972 ), designed by araldo cossutta of i. m. pei & associates, which until 2008 housed the administrative staff from the church ' s 15 departments. there is also a children ' s fountain and a 690 ft × 100 ft ( 210 m × 30 m ) reflecting pool. = = = manual of the mother church = = = eddy ' s manual of the mother church ( first published 1895 ) lists the church ' s by - laws. requirements for members include daily prayer and daily study of the bible and science and health. members must subscribe to church periodicals if they can afford to, and pay an annual tax to the church of not less than one dollar. prohibitions include engaging in mental malpractice ; visiting a store that sells " obnoxious " books ; joining other churches ; publishing articles that are uncharitable toward religion, medicine, the courts or the law ; and publishing the number of church members. the manual also prohibits engaging in public debate about christian science without board approval, and learning hypnotism. it includes " the golden rule " : " a member of the mother church shall not haunt mrs. eddy ' s drive when she goes out, continually stroll by her house, or make a summer resort near her for such a purpose. " = = = services = = = the church of christ, scientist is a lay church which has no ordained clergy or rituals, and performs no baptisms ; with clergy of other faiths often performing marriage or funeral services since they have no clergy of their own. its main religious texts are the bible and science and health. each church has two readers, who read aloud a " bible lesson " or " lesson sermon " made up of selections from those texts during the sunday service, and a shorter set of readings to open wednesday evening testimony meetings. in addition to readings, members offer testimonials during the main portion of the wednesday meetings, including recovery from
|
https://en.wikipedia.org/wiki/Christian_Science
|
we apply a novel framework for decomposing and reasoning about free space in an environment to a multi - agent persistent monitoring problem. our decomposition method represents free space as a collection of ellipsoids associated with a weighted connectivity graph. the same ellipsoids used for reasoning about connectivity and distance during high level planning can be used as state constraints in a model predictive control algorithm to enforce collision - free motion. this structure allows for streamlined implementation in distributed multi - agent tasks in 2d and 3d environments. we illustrate its effectiveness for a team of tracking agents tasked with monitoring a group of target agents. our algorithm uses the ellipsoid decomposition as a primitive for the coordination, path planning, and control of the tracking agents. simulations with four tracking agents monitoring fifteen dynamic targets in obstacle - rich environments demonstrate the performance of our algorithm.
|
arxiv:2205.15473
|
using the first long - term photometry from the transiting exoplanet survey satellite, we have carried out a detailed time - resolved timing analysis of an intermediate polar tx col. the power spectra of almost 52 days continuous time - series data reveal the orbital period of $ 5. 691 \ pm 0. 006 $ hr, spin period of $ 1909. 5 \ pm 0. 2 $ s, and beat period of $ 2105. 76 \ pm 0. 25 $ s, which is consistent with the earlier results. we have also found the presence of quasi - periodic oscillations ( qpos ) for a few days with a period of 5850 - 5950 s, which appears to be due to the beating of the keplerian period with the spin period of the white dwarf. the continuous data allowed us to look thoroughly at the day - wise evolution of the system ' s accretion geometry. we report here that the tx col changes its accretion mechanism even on a time - scale of one day, confirming its variable disk - overflow accretion nature. for the majority of the time, it was found to be disk - overflow system with stream - fed dominance, however, pure disk - fed and pure stream - fed accretions cannot be ruled out during the observations.
|
arxiv:2104.06944
|
with continuous progression of moore ' s law, integrated circuit ( ic ) device complexity is also increasing. scanning electron microscope ( sem ) image based extensive defect inspection and accurate metrology extraction are two main challenges in advanced node ( 2 nm and beyond ) technology. deep learning ( dl ) algorithm based computer vision approaches gained popularity in semiconductor defect inspection over last few years. in this research work, a new semiconductor defect inspection framework " semi - diffusioninst " is investigated and compared to previous frameworks. to the best of the authors ' knowledge, this work is the first demonstration to accurately detect and precisely segment semiconductor defect patterns by using a diffusion model. different feature extractor networks as backbones and data sampling strategies are investigated towards achieving a balanced trade - off between precision and computing efficiency. our proposed approach outperforms previous work on overall map and performs comparatively better or as per for almost all defect classes ( per class aps ). the bounding box and segmentation maps achieved by the proposed semi - diffusioninst model are improved by 3. 83 % and 2. 10 %, respectively. among individual defect types, precision on line collapse and thin bridge defects are improved approximately 15 \ % on detection task for both defect types. it has also been shown that by tuning inference hyperparameters, inference time can be improved significantly without compromising model precision. finally, certain limitations and future work strategy to overcome them are discussed.
|
arxiv:2307.08693
|
aims. we investigate the ortho - water abundance in outflows and shocks in order to improve our knowledge of shock chemistry and of the physics behind molecular outflows. methods. we have used the odin space observatory to observe the h2o ( 110 - 101 ) line. we obtain strip maps and single pointings of 13 outflows and two supernova remnants where we report detections for eight sources. we have used radex to compute the beam averaged abundances of o - h2o relative to h2. in the case of non - detection, we derive upper limits on the abundance. results. observations of co emission from the literature show that the volume density of h2 can vary to a large extent, a parameter that puts severe uncertainties on the derived abundances. our analysis shows a wide range of abundances reflecting the degree to which shock chemistry is affecting the formation and destruction of water. we also compare our results with recent results from the swas team. conclusions. elevated abundances of ortho - water are found in several sources. the abundance reaches values as high as what would be expected from a theoretical c - type shock where all oxygen, not in the form of co, is converted to water. however, the high abundances we derive could also be due to the low densities ( derived from co observations ) that we assume. the water emission may in reality stem from high density regions much smaller than the odin beam. we do not find any relationship between the abundance and the mass loss rate. on the other hand, there is a relation between the derived water abundance and the observed maximum outflow velocity.
|
arxiv:0908.4341
|
the search for the true ground state of the dense matter remains open since bodmer, terazawa and other raised the possibility of stable quarks, boosted by witten ' s $ strange $ $ matter $ hypothesis in 1984. within this proposal, the strange matter is assumed to be composed of $ strange $ quarks in addition to the usual $ up $ s and $ down $ s, having an energy per baryon lower than the strangeless counterpart, and even lower than that of nuclear matter. in this sense, neutron stars should actually be strange stars. later work showed that a paired, symmetric in flavor, color - flavor locked ( cfl ) state would be preferred to the one without any pairing for a wide range of the parameters ( gap $ \ delta $, strange quark mass $ m _ s $, and bag constant b ). we use an approximate, yet very accurate, cfl equation of state ( eos ) that generalizes the mit bag model to obtain two families of exact solutions for the static einstein field equations constructing families anisotropic compact relativistic objects. in this fashion, we provide exact useful solutions directly connected with microphysics.
|
arxiv:1906.11311
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.