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what are the most important conditions and processes governing the growth of stellar - origin compact objects? the identification of compact object type as either black hole ( bh ) or neutron star ( ns ) is fundamental to understanding their formation and evolution. to date, time - domain determination of compact object type remains a relatively untapped tool. measurement of orbital periods, pulsations, and bursts will lead to a revolution in the study of the demographics of ns and bh populations, linking source phenomena to accretion and galaxy parameters ( e. g., star formation, metallicity ). to perform these measurements over sufficient parameter space, a combination of a wide - field ( > 5000 deg ^ 2 ) transient x - ray monitor over a dynamic energy range ( ~ 1 - 100 kev ) and an x - ray telescope for deep surveys with < 5 arcsec psf half - energy width ( hew ) angular resolution are required. synergy with multiwavelength data for characterizing the underlying stellar population will transform our understanding of the time domain properties of transient sources, helping to explain details of supernova explosions and gravitational wave event rates.
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arxiv:1903.09858
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an orthogonal representation of a graph is an assignment of nonzero real vectors to its vertices such that distinct non - adjacent vertices are assigned to orthogonal vectors. we prove general lower bounds on the dimension of orthogonal representations of graphs using the borsuk - ulam theorem from algebraic topology. our bounds strengthen the kneser conjecture, proved by lov \ ' asz in 1978, and some of its extensions due to b \ ' ar \ ' any, schrijver, dol ' nikov, and kriz. as applications, we determine the integrality gap of fractional upper bounds on the shannon capacity of graphs and the quantum one - round communication complexity of certain promise equality problems.
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arxiv:1811.11488
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between 19 and 54 gpa, potassium has a complex composite incommensurate host - guest structure which undergoes two intraphase transitions over this pressure range. the temperature dependence of these host - guest phases is further complicated by the onset of an order - disorder transition in their guest chains. here, we report single crystal, quasi - single crystal, and powder synchrotron x - ray diffraction measurements of this order - disorder phenomenon in incommensurate potassium to 47 gpa and 750 k. the so - called chain " melting " transition is clearly visible over a 22 gpa pressure range, and there are significant changes in the slope of the phase boundary which divides the ordered and disordered phases, one of which results from the intraphase transitions in the guest structure.
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arxiv:1504.02895
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we calculate the energy spectrum of a confining flux tube that is closed around a spatial torus, as a function of its length l. we do so for various su ( n ) gauge theories in 3 + 1 dimensions, and for various values of spin, parity and longitudinal momentum. we are able to present usefully accurate results for about 20 of the lightest such states, for a range of l that begins close to the ( finite volume ) deconfining phase transition, and extends up to l. sqrt ( k ) ~ 6 ( where k is the string tension ). we find that most of these low - lying states are well described by the spectrum of the nambu - goto free string theory in flat space - time. remarkably, this is so not only at the larger values of l, where the gap between the ground state energy and the low - lying excitations becomes small compared to the mass gap, but also down to much shorter lengths where these excitation energies become large compared to sqrt ( k ), the flux - tube no longer ` looks ' anything like a thin string, and an expansion of the effective string action in powers of 1 / l no longer converges. all this is for flux in the fundamental representation. we also calculate the k = 2 ( anti ) symmetric ground states and these show larger corrections at small l. so far all this closely resembles our earlier findings in 2 + 1 dimensions. however, and in contrast to the situation in d = 2 + 1, we also find that there are some states, with j, p = 0, - quantum numbers, that show large deviations from the nambu - goto spectrum. we investigate the possibility that ( some of ) these states may encode the massive modes associated with the internal structure of the flux tube, and we discuss how the precocious free string behaviour of most states constrains the effective string action, on which much interesting theoretical progress has recently been made.
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arxiv:1007.4720
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this paper is the first in a series presenting a sample of 29 late - type dwarf galaxies, observed with the westerbork synthesis radio telescope ( wsrt ) in the 21 - cm line of neutral atomic hydrogen ( hi ). the sample itself, the hi content of and the hi distribution in the sample galaxies are briefly discussed. four sample galaxies were also detected in the continuum.
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arxiv:astro-ph/0203128
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landau ' s theory of electron motion in stationary magnetic fields is extended to the inclusion of bouncing along the field between mirror points in an inhomogeneous field. the problem can be treated perturbation theoretically. as expected, bouncing is quantized, causes a weak shift in landau levels, reduces parallel degeneracy, but does not contribute to diamagnetism.
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arxiv:1305.1000
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the need for data preservation and reproducible research is widely recognized in the scientific community. yet, researchers often struggle to find the motivation to contribute to data repositories and to use tools that foster reproducibility. in this paper, we explore possible uses of gamification to support reproducible practices in high energy physics. to understand how gamification can be effective in research tools, we participated in a workshop and performed interviews with data analysts. we then designed two interactive prototypes of a research preservation service that use contrasting gamification strategies. the evaluation of the prototypes showed that gamification needs to address core scientific challenges, in particular the fair reflection of quality and individual contribution. through thematic analysis, we identified four themes which describe perceptions and requirements of gamification in research : contribution, metrics, applications and scientific practice. based on these, we discuss design implications for gamification in science.
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arxiv:1903.02446
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the reconfiguration graph of the $ k $ - colourings, denoted $ \ mathcal { r } _ k ( g ) $, is the graph whose vertices are the $ k $ - colourings of $ g $ and two colourings are adjacent in $ \ mathcal { r } _ k ( g ) $ if they differ in colour on exactly one vertex. in this paper, we investigate the connectivity and diameter of $ \ mathcal { r } _ { k + 1 } ( g ) $ for a $ k $ - colourable graph $ g $ restricted by forbidden induced subgraphs. we show that $ \ mathcal { r } _ { k + 1 } ( g ) $ is connected for every $ k $ - colourable $ h $ - free graph $ g $ if and only if $ h $ is an induced subgraph of $ p _ 4 $ or $ p _ 3 + p _ 1 $. we also start an investigation into this problem for classes of graphs defined by two forbidden induced subgraphs. we show that if $ g $ is a $ k $ - colourable ( $ 2k _ 2 $, $ c _ 4 $ ) - free graph, then $ \ mathcal { r } _ { k + 1 } ( g ) $ is connected with diameter at most $ 4n $. furthermore, we show that $ \ mathcal { r } _ { k + 1 } ( g ) $ is connected for every $ k $ - colourable ( $ p _ 5 $, $ c _ 4 $ ) - free graph $ g $.
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arxiv:2206.09268
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in this paper, we are concerned with hypersurfaces in $ h ^ n \ times r $ with constant r - mean curvature, to be called $ h _ r $ - hypersurfaces. we construct examples of complete $ h _ r $ - hypersurfaces which are invariant by parabolic screw motion or by rotation. we prove that there is a unique rotational strictly convex entire $ h _ r $ - graph for each value $ 0 < h _ r \ leq \ frac { n - r } { n } $. also, for each value $ h _ r > \ frac { n - r } { n } $, there is a unique embedded compact strictly convex rotational $ h _ r $ - hypersurface. by using them as barriers, we obtain some interesting geometric results, including height estimates and an alexandrov - type theorem. namely, we prove that an embedded compact $ h _ r $ - hypersurface in $ h ^ n \ times r $ is rotational ( $ h _ r > 0 $ ).
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arxiv:1402.6886
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microrobots show great potential in biomedical applications such as drug delivery and cell manipulations. however, current microrobots are mostly fabricated as a single entity and type and the tasks they can perform are limited. in this paper, modular microrobots, with an overall size of 120 $ \ mu $ m $ \ times $ 200 $ \ mu $ m, are proposed with responsive mating components, made from stimuli - responsive hydrogels, and application specific end - effectors for microassembly tasks. the modular microrobots are fabricated based on photolithography and two - photon polymerization together or separately. two types of modular microrobots are created based on the location of the responsive mating component. the first type of modular microrobot has a mating component that can shrink upon stimulation while the second type has a double bilayer structure that can realize an open and close motion. the exchange of end - effectors with an identical actuation base is demonstrated for both types of microrobots. finally, different manipulation tasks are performed with different types of end - effectors.
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arxiv:2311.13809
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we study the pointwise ( in the space and time variables ) behavior of the fokker - planck equation with flat confinement. the solution has very clear description in the $ xt - $ plane, including large time behavior, initial layer and asymptotic behavior. moreover, the structure of the solution highly depends on the potential function.
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arxiv:1706.07557
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as immersive technologies enable unique, multimodal interaction methods, developers must also use tailored methods to support user accessibility, distinct from traditional software practices. therefore, we interviewed 25 industry extended reality ( xr ) developers, including freelancers, startups, midsize, and big tech companies about their motivations, techniques, barriers, and attitudes towards incorporating accessibility features in their xr apps. our study revealed a variety of challenges, including conflicting priorities between application and platform developers regarding accessibility infrastructure ; startups rapid development culture prohibiting accessible development ; and the lack of accessible interaction design considerations at the ideation, design, and early prototyping stages. as a comprehensive set of xr accessibility guidelines has yet to be established, we also compiled and evaluated a set of accessibility guidelines for 3d virtual worlds and addressed their limitations when applied to xr. finally, we inform the creation of effective support methods for industry developers.
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arxiv:2412.16321
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we report on the investigation of a very high energy ( vhe ), galactic gamma - ray source recently discovered at > 50gev using the large area telescope ( lat ) on board the fermi gamma - ray space telescope. this object, 2fhl j1703. 4 - 4145, displays a very hard > 50gev spectrum with a photon index ~ 1. 2 in the 2fhl catalog and, as such, is one of the most extreme sources in the 2fhl sub - sample of galactic objects. a detailed analysis of the available multi - wavelength data shows that this source is located on the western edge of the supernova remnant ( snr ) g344. 7 - - 0. 1, along with extended tev source, hess j1702 - 420. the observations and the spectral energy distribution modeling support a scenario where this gamma - ray source is the byproduct of the interaction between the snr shock and the dense surrounding medium, with escaping cosmic rays ( crs ) diffusing into the dense environment and interacting with a large local cloud, generating the observed tev emission. if confirmed, an interaction between the snr crs and a nearby cloud would make 2fhl j1703. 4 - 4145 another promising candidate for efficient particle acceleration of the 2fhl galactic sample, following the first candidate from our previous investigation of a likely shock - cloud interaction occurring on the west edge of the vela snr.
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arxiv:2006.08757
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the difficulty that the probabilities infinitely increase with time as time is long enough in time - dependent perturbation theory for some quantum systems is resolved by means of simply transforming the perturbative series into natural exponential functions of the re - summed perturbative series. three exactly solvable models are taken to check our new formulation, and excellent agreements with the exact solution are achieved.
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arxiv:1605.00741
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bankruptcy is a legal procedure that claims a person or organization as a debtor. it is essential to ascertain the risk of bankruptcy at initial stages to prevent financial losses. in this perspective, different soft computing techniques can be employed to ascertain bankruptcy. this study proposes a bankruptcy prediction system to categorize the companies based on extent of risk. the prediction system acts as a decision support tool for detection of bankruptcy keywords : bankruptcy, soft computing, decision support tool
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arxiv:1502.03601
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- time chatting in a group setting. participants can raise their hands, answer polls, or take tests. students can whiteboard and screencast when given rights by the instructor, who sets permission levels for text notes, microphone rights, and mouse control. a virtual classroom provides an opportunity for students to receive direct instruction from a qualified teacher in an interactive environment. learners can have direct and immediate access to their instructor for instant feedback and direction. the virtual classroom provides a structured schedule of classes, which can be helpful for students who may find the freedom of asynchronous learning to be overwhelming. besides, the virtual classroom provides a social learning environment that replicates the traditional " brick and mortar " classroom. in higher education especially, a virtual learning environment ( vle ) is sometimes combined with a management information system ( mis ) to create a managed learning environment, in which all aspects of a course are handled through a consistent user interface throughout the institution. physical universities and newer online - only colleges offer to select academic degrees and certificate programs via the internet. some programs require students to attend some campus classes or orientations, but many are delivered completely online. several universities offer online student support services, such as online advising and registration, e - counseling, online textbook purchases, student governments, and student newspapers. due to the covid - 19 pandemic, many schools have been forced to move online. as of april 2020, an estimated 90 % of high - income countries are offering online learning, with only 25 % of low - income countries offering the same. = = = = augmented reality = = = = ar technology plays an important role in the future of the classroom where human co - orchestration takes place seamlessly. = = = learning management system = = = a learning management system ( lms ) is software used for delivering, tracking, and managing training and education. it tracks data about attendance, time on task, and student progress. educators can post announcements, grade assignments, check on course activities, and participate in class discussions. students can submit their work, read and respond to discussion questions, and take quizzes. an lms may allow teachers, administrators, and students, and permitted additional parties ( such as parents, if appropriate ) to track various metrics. lmss range from systems for managing training / educational records to software for distributing courses over the internet and offering features for online collaboration. the creation and maintenance of comprehensive learning content require substantial initial and ongoing investments in human labor. effective translation into other languages and cultural contexts requires even
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https://en.wikipedia.org/wiki/Educational_technology
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i discuss the absorption and dispersion of pions in hot matter. a two - loop calculation in the framework of chiral perturbation theory is presented and its result is compactly written in terms of the two - and three - particle forward $ \ pi \ pi $ scattering amplitudes. at modest temperatures, $ t \ le 100 $ mev, the change in the pion mass is small and its dispersion law closely resembles the free space one. at these temperatures, all quantities of interest are given to a good degree of accuracy by the first term in the virial expansion which is linear in the density. ( butp - 93 / 16, uses espcrc1. sty from north - holland publishing )
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arxiv:hep-ph/9306275
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we present results for pseudoscalar decay constants of heavy - light mesons using both quenched and n _ f = 2 dynamical fermion configurations. a variety of fermion actions is investigated : wilson, nonperturbative clover, and fat - link clover. for heavy quarks the fermilab formalism is applied. in the quenched approximation, results with the nonperturbatively improved clover action of the alpha collaboration allow us to study the systematic error of the continuum extrapolation from the wilson action. in addition, we use quenched configurations to explore the effects of fattening. the lessons from the quenched analyses are then applied to data with dynamical fermions, where both wilson and fat - link clover actions have been used. this allows us to attempt a continuum extrapolation of the dynamical results.
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arxiv:hep-lat/0011029
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we provide a new proof of hua ' s result that every sufficiently large integer n \ equiv 5 ( mod \, 24 ) can be written as the sum of the five prime squares. hua ' s original proof relies on the circle method and uses results from the theory of $ l $ - functions. here, we present a proof based on the transference principle first introduced by green. using a sieve theoretic approach similar to the work by shao, we do not require any results related to the distributions of zeros of l - functions. the main technical difficulty of our approach lies in proving the pseudorandomness of the majorant of the characteristic function of the w - tricked primes which requires a precise evaluation of the occurring gaussian sums and jacobi symbols.
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arxiv:1711.08578
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we report the mechanism of cleavage crack deviation at grain boundaries. a fracture mechanics based model has been developed to combine the effect of tilt and twist angles between cleavage planes on the reduction in normalized energy release rate. furthermore, electron back - scatter diffraction analysis on cleavage fracture surface has been carried out. the microstructural features associated with the presence of tilt and twist angle at the grain boundary have been identified and found to be consistent with the prediction from the analytical model.
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arxiv:1902.04252
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in this paper we propose a hamiltonian of the n - level system by making use of generalized pauli matrices.
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arxiv:quant-ph/0302050
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weak neutral current interactions with charged leptons have offered unique opportunities to study novel aspects of hadronic structure and search for physics beyond the standard model. these studies in the medium energy community have been primarily through parity - violating processes with electron beams, but with the possibility of polarized positron beams, new and complementary observables can be considered in experiments analogous to their electron counterparts. such studies include elastic proton, deep inelastic, and electron target scattering. potential positron neutral current experiments along with their potential physics reach, requirements, and feasibility are presented.
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arxiv:1712.05314
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we investigate the strong gravitational lensing in a squashed kaluza - klein black hole immersed in the g \ " { o } del universe with global rotation. our result show that the strong gravitational lensing in the squashed kaluza - klein g \ " { o } del black hole spacetime has some distinct behaviors from that in the kerr case. in the squashed kaluza - klein g \ " { o } del black hole spacetime, the photon sphere radius, the minimum impact parameter, the coefficient $ \ bar { a } $, $ \ bar { b } $ and the deflection angle $ \ alpha ( \ theta ) $ in the $ \ phi $ direction are independent of whether the photon goes with or against the global rotation of the g \ " { o } del universe. while in the kerr black hole, the values of these quantities for the prograde photons are different from those for the retrograde photons. moreover, the coefficient of $ \ bar { b } $ increases with $ j $ in the squashed kaluza - klein g \ " { o } del black hole, but decreases with $ a $ in the kerr case. we also probe the influence of the squashed effect on the strong gravitational lensing in this black hole and find that in the extremely squashed case $ \ rho _ 0 = 0 $, the coefficient $ \ bar { a } $ is a constant 1 and is independent of the global rotation of the g \ " { o } del universe. furthermore, we assume that the gravitational field of the supermassive central object of the galaxy can be described by this metric and estimate the numerical values of the coefficients and the main observables in the strong gravitational lensing.
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arxiv:1102.0086
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a massless up quark is an intriguing solution to the strong cp problem. we discuss how lattice computations can be used in conjunction with chiral perturbation theory to address the consistency of $ m _ u = 0 $ with the observed hadron spectrum and interactions. it is not necessary to simulate very light quarks - three flavor partially quenched computations with comparable sea and valence quark masses on the order of the strange quark mass could suffice.
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arxiv:hep-lat/9909091
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since the invention of word2vec, the skip - gram model has significantly advanced the research of network embedding, such as the recent emergence of the deepwalk, line, pte, and node2vec approaches. in this work, we show that all of the aforementioned models with negative sampling can be unified into the matrix factorization framework with closed forms. our analysis and proofs reveal that : ( 1 ) deepwalk empirically produces a low - rank transformation of a network ' s normalized laplacian matrix ; ( 2 ) line, in theory, is a special case of deepwalk when the size of vertices ' context is set to one ; ( 3 ) as an extension of line, pte can be viewed as the joint factorization of multiple networks ' laplacians ; ( 4 ) node2vec is factorizing a matrix related to the stationary distribution and transition probability tensor of a 2nd - order random walk. we further provide the theoretical connections between skip - gram based network embedding algorithms and the theory of graph laplacian. finally, we present the netmf method as well as its approximation algorithm for computing network embedding. our method offers significant improvements over deepwalk and line for conventional network mining tasks. this work lays the theoretical foundation for skip - gram based network embedding methods, leading to a better understanding of latent network representation learning.
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arxiv:1710.02971
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we study the charge transport across a band - tuned metal - insulator transition in two dimensions. for high temperatures $ t $ and chemical potentials $ \ mu $ far from the transition point, conduction is ballistic and the resistance $ r ( t ) $ verifies a simple one - parameter scaling relation. here, we explore the limits of this semi - classical behaviour and study the quantum regime beyond, where scaling breaks down. we derive an analytical formula for the simplest feynman diagram of the linear - response conductivity $ \ sigma = 1 / r $ of a parabolic band endowed with a finite lifetime. our formula shows excellent agreement for experiments for a field - tuned mote $ _ 2 $ / wse $ _ 2 $ moir \ ' e bilayer, and can capture the quantum effects responsible for breaking the one - parameter scaling. we go on to discuss a fascinating prediction of our model : the resistance at the quantum - critical band - tuned lifshitz point ( $ \ mu = t = 0 $ ) has the universal value, $ r _ l = ( 2 \ pi h ) / e ^ 2 $, per degree of freedom and this value is found to be compatible with experiment. furthermore, we investigate whether two dimensional metal - insulator transitions driven by strong electron correlations or disorder can also be classified by their quantum - critical resistance and find that $ r _ l $ may be useful in identifying predominantly interaction driven transitions.
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arxiv:2501.17616
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we present a model treating the kinetics of adsorption of soluble surface - active molecules at the interface between an aqueous solution and another fluid phase. the model accounts for both the diffusive transport inside the solution and the kinetics taking place at the interface using a free - energy formulation. in addition, it offers a general method of calculating dynamic surface tensions. non - ionic surfactants are shown, in general, to undergo a diffusion - limited adsorption, in accord with experimental findings.
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arxiv:cond-mat/9803320
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carbon fiber composite can be a potential candidate for replacing metal - based battery enclosures of current electric vehicles ( e. v. s ) owing to its better strength - to - weight ratio and corrosion resistance. however, the strength of carbon fiber - based structures depends on several parameters that should be carefully chosen. in this work, we implemented high throughput finite element analysis ( fea ) based thermoforming simulation to virtually manufacture the battery enclosure using different design and processing parameters. subsequently, we performed virtual crash simulations to mimic a side pole crash to evaluate the crashworthiness of the battery enclosures. this high throughput crash simulation dataset was utilized to build predictive models to understand the crashworthiness of an unknown set. our machine learning ( ml ) models showed excellent performance ( r2 > 0. 97 ) in predicting the crashworthiness metrics, i. e., crush load efficiency, absorbed energy, intrusion, and maximum deceleration during a crash. we believe that this fea - ml work framework will be helpful in down select process parameters for carbon fiber - based component design and can be transferrable to other manufacturing technologies.
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arxiv:2309.00637
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we compute the effective lagrangian of static gravitational fields interacting with thermal fields. our approach employs the usual imaginary time formalism as well as the equivalence between the static and space - time independent external gravitational fields. this allows to obtain a closed form expression for the thermal effective lagrangian in $ d $ space - time dimensions.
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arxiv:1203.1670
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with the needs of science and business, data sharing and re - use has become an intensive activity for various areas. in many cases, governance imposes rules concerning data use, but there is no existing computational technique to help data - users comply with such rules. we argue that intelligent systems can be used to improve the situation, by recording provenance records during processing, encoding the rules and performing reasoning. we present our initial work, designing formal models for data rules and flow rules and the reasoning system, as the first step towards helping data providers and data users sustain productive relationships.
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arxiv:1911.08439
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physical interactions can often help reveal information that is not readily apparent. for example, we may tug at a table leg to evaluate whether it is built well, or turn a water bottle upside down to check that it is watertight. we propose to train robots to acquire such interactive behaviors automatically, for the purpose of evaluating the result of an attempted robotic skill execution. these evaluations in turn serve as " interactive reward functions " ( irfs ) for training reinforcement learning policies to perform the target skill, such as screwing the table leg tightly. in addition, even after task policies are fully trained, irfs can serve as verification mechanisms that improve online task execution. for any given task, our irfs can be conveniently trained using only examples of successful outcomes, and no further specification is needed to train the task policy thereafter. in our evaluations on door locking and weighted block stacking in simulation, and screw tightening on a real robot, irfs enable large performance improvements, even outperforming baselines with access to demonstrations or carefully engineered rewards. project website : https : / / sites. google. com / view / lirf - corl - 2022 /
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arxiv:2212.08961
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we report the discovery of a bright ( j = 13. 83 $ \ pm $ 0. 03 ) methane brown dwarf, or t dwarf, by the two micron all sky survey. this object, 2massi j0559191 - 140448, is the first brown dwarf identified by the newly commissioned cormass instrument mounted on the palomar 60 - inch telescope. near - infrared spectra from 0. 9 - 2. 35 $ \ micron $ show characteristic ch $ _ 4 $ bands at 1. 1, 1. 3, 1. 6, and 2. 2 $ \ micron $, which are significantly shallower than those seen in other t dwarfs discovered to date. coupled with the detection of an feh band at 0. 9896 $ \ micron $ and two sets of k i doublets at j - band, we propose that 2mass j0559 - 14 is a warm t dwarf, close to the transition between l and t spectral classes. the brightness of this object makes it a good candidate for detailed investigation over a broad wavelength regime and at higher resolution.
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arxiv:astro-ph/0004239
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we consider finite macroscopic systems, i. e., systems of large but finite degrees of freedom, which we believe are poorly understood as compared with small systems and infinite systems. we focus on pure states that do not have the ` cluster property. ' such a pure state is entangled macroscopically, and is quite anomalous in view of many - body physics because it does not approach any pure state in the infinite - size limit. however, we often encounter such anomalous states when studying finite macroscopic systems, such as quantum computers with many qubits and finite systems that will exhibit symmetry breaking in the infinite - size limit. we study stabilities of such anomalous states in general systems. in contrast to the previous works, we obtain general and universal results, by making full use of the locality of the theory. using the general results, we discuss roles of anomalous states in quantum computers, and the mechanism of emergence of a classical world from quantum theory.
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arxiv:quant-ph/0311176
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for the problems indicated in the title, a further development of a new approach ( different from those applied before ) is given. a basic problem under consideration arises in viscous incompressible fluid dynamics and describes self - similar solutions to the boundary layer equation for a stream function with zero pressure gradient ( connected with the plane - parallel laminar flow in a mixing layer ). some previous results concerning singular nonlinear cauchy problems, smooth stable initial manifolds, and parametric exponential lyapunov series are used to state correctly and analyze the singular " initial - boundary - value " problem for a third - order nonlinear ordinary differential equation defined on the entire real axis. the detailed analysis of this singular nonlinear problem leads, in particular, to efficient methods for solving it approximately and gives a possibility to obtain numerically the particle trajectories in the plane of flow. some results of the numerical experiments are displayed and their physical interpretation is discussed. a connection of this basic problem with some known physical and mathematical problems, arising for self - similar solutions to the boundary layer equations with zero pressure gradient, is described, namely the " flooded jet ", the plane " semi - jet " and the " near - wall jet " problems are considered which are of interest by themselves.
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arxiv:1804.06301
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articulated object manipulation poses a unique challenge compared to rigid object manipulation as the object itself represents a dynamic environment. in this work, we present a novel rl - based pipeline equipped with variable impedance control and motion adaptation leveraging observation history for generalizable articulated object manipulation, focusing on smooth and dexterous motion during zero - shot sim - to - real transfer. to mitigate the sim - to - real gap, our pipeline diminishes reliance on vision by not leveraging the vision data feature ( rgbd / pointcloud ) directly as policy input but rather extracting useful low - dimensional data first via off - the - shelf modules. additionally, we experience less sim - to - real gap by inferring object motion and its intrinsic properties via observation history as well as utilizing impedance control both in the simulation and in the real world. furthermore, we develop a well - designed training setting with great randomization and a specialized reward system ( task - aware and motion - aware ) that enables multi - staged, end - to - end manipulation without heuristic motion planning. to the best of our knowledge, our policy is the first to report 84 \ % success rate in the real world via extensive experiments with various unseen objects.
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arxiv:2502.14457
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kink oscillations of coronal loops, i. e., standing kink waves, is one of the most studied dynamic phenomena in the solar corona. the oscillations are excited by impulsive energy releases, such as low coronal eruptions. typical periods of the oscillations are from a few to several minutes, and are found to increase linearly with the increase in the major radius of the oscillating loops. it clearly demonstrates that kink oscillations are natural modes of the loops, and can be described as standing fast magnetoacoustic waves with the wavelength determined by the length of the loop. kink oscillations are observed in two different regimes. in the rapidly decaying regime, the apparent displacement amplitude reaches several minor radii of the loop. the damping time which is about several oscillation periods decreases with the increase in the oscillation amplitude, suggesting a nonlinear nature of the damping. in the decayless regime, the amplitudes are smaller than a minor radius, and the driver is still debated. the review summarises major findings obtained during the last decade, and covers both observational and theoretical results. observational results include creation and analysis of comprehensive catalogues of the oscillation events, and detection of kink oscillations with imaging and spectral instruments in the euv and microwave bands. theoretical results include various approaches to modelling in terms of the magnetohydrodynamic wave theory. properties of kink oscillations are found to depend on parameters of the oscillating loop, such as the magnetic twist, stratification, steady flows, temperature variations and so on, which make kink oscillations a natural probe of these parameters by the method of magnetohydrodynamic seismology.
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arxiv:2109.11220
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this paper introduces bayesian frameworks for tackling various aspects of multi - criteria decision - making ( mcdm ) problems, leveraging a probabilistic interpretation of mcdm methods and challenges. by harnessing the flexibility of bayesian models, the proposed frameworks offer statistically elegant solutions to key challenges in mcdm, such as group decision - making problems and criteria correlation. additionally, these models can accommodate diverse forms of uncertainty in decision makers ' ( dms ) preferences, including normal and triangular distributions, as well as interval preferences. to address large - scale group mcdm scenarios, a probabilistic mixture model is developed, enabling the identification of homogeneous subgroups of dms. furthermore, a probabilistic ranking scheme is devised to assess the relative importance of criteria and alternatives based on dm ( s ) preferences. through experimentation on various numerical examples, the proposed frameworks are validated, demonstrating their effectiveness and highlighting their distinguishing features in comparison to alternative methods.
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arxiv:2208.13390
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the central molecular zone ( cmz ), usually referring to the inner 500 pc of the galaxy, contains a dozen of massive ( $ \ sim10 ^ 5 $ $ m _ \ odot $ ) molecular clouds. are these clouds going to actively form stars like sgr b2? how are they affected by the extreme physical conditions in the cmz, such as strong turbulence? here we present a first step towards answering these questions. using high - sensitivity, high angular resolution radio and ( sub ) millimeter observations, we studied deeply embedded star formation in six massive clouds in the cmz, including the 20 and 50 km s $ ^ { - 1 } $ clouds, sgr b1 off ( as known as dust ridge clouds e / f ), sgr c, sgr d, and g0. 253 - 0. 016. the vla water maser observations suggest a population of deeply embedded protostellar candidates, many of which are new detections. the sma 1. 3 mm continuum observations reveal peaks in dust emission associated with the masers, suggesting the existence of dense cores. while our findings confirm that clouds such as g0. 253 - 0. 016 lack internal compact substructures and are quiescent in terms of star formation, two clouds ( the 20 km s $ ^ { - 1 } $ cloud and sgr c ) stand out with clusters of water masers with associated dense cores which may suggest a population of deeply embedded protostars at early evolutionary phases. follow - up observations with vla and alma are necessary to confirm their protostellar nature.
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arxiv:1609.08240
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factorization of large dense matrices are ubiquitous in engineering and data science applications, e. g. preconditioners for iterative boundary integral solvers, frontal matrices in sparse multifrontal solvers, and computing the determinant of covariance matrices. hss and $ \ mathcal { h } ^ 2 $ - matrices are hierarchical low - rank matrix formats that can reduce the complexity of factorizing such dense matrices from $ \ mathcal { o } ( n ^ 3 ) $ to $ \ mathcal { o } ( n ) $. for hss matrices, it is possible to remove the dependency on the trailing matrices during cholesky / lu factorization, which results in a highly parallel algorithm. however, the weak admissibility of hss causes the rank of off - diagonal blocks to grow for 3 - d problems, and the method is no longer $ \ mathcal { o } ( n ) $. on the other hand, the strong admissibility of $ \ mathcal { h } ^ 2 $ - matrices allows it to handle 3 - d problems in $ \ mathcal { o } ( n ) $, but introduces a dependency on the trailing matrices. in the present work, we pre - compute the fill - ins and integrate them into the shared basis, which allows us to remove the dependency on trailing - matrices even for $ \ mathcal { h } ^ 2 $ - matrices. comparisons with a block low - rank factorization code lorapo showed a maximum speed up of 4, 700x for a 3 - d problem with complex geometry.
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arxiv:2208.10907
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with respect to spatial overlap, cnn - based segmentation of short axis cardiovascular magnetic resonance ( cmr ) images has achieved a level of performance consistent with inter observer variation. however, conventional training procedures frequently depend on pixel - wise loss functions, limiting optimisation with respect to extended or global features. as a result, inferred segmentations can lack spatial coherence, including spurious connected components or holes. such results are implausible, violating the anticipated topology of image segments, which is frequently known a priori. addressing this challenge, published work has employed persistent homology, constructing topological loss functions for the evaluation of image segments against an explicit prior. building a richer description of segmentation topology by considering all possible labels and label pairs, we extend these losses to the task of multi - class segmentation. these topological priors allow us to resolve all topological errors in a subset of 150 examples from the acdc short axis cmr training data set, without sacrificing overlap performance.
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arxiv:2008.09585
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we try to obtain born ' s principle as a result of a subquantum heat death, using classical $ { \ cal h } $ - theorem and the definition of a proper quantum $ { \ cal h } $ - theorem, within the framwork of bohm ' s theory. we shall show the possibility of solving the problem of action - reaction asymmetry present in bohm ' s theory and the arrow of time problem in our procedure.
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arxiv:quant-ph/9808015
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we report the firm discovery of solar - like oscillations in a giant star. we monitored the star xi hya ( g7iii ) continuously during one month with the coralie spectrograph attached to the 1. 2m swiss euler telescope. the 433 high - precision radial - velocity measurements clearly reveal multiple oscillation frequencies in the range 50 - 130 uhz, corresponding to periods between 2. 0 and 5. 5 hours. the amplitudes of the strongest modes are slightly smaller than 2 m / s. current model calculations are compatible with the detected modes.
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arxiv:astro-ph/0209325
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after defining reduced minimum braid word and criteria for a braid family representative, different braid family representatives are derived, and a correspondence between them and families of knots and links given in conway notation is established.
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arxiv:math/0504479
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we point out the $ cp $ asymmetry in the chain decay of $ \ lambda _ c ^ + \ to \ delta ^ + k ( t ) ( \ to \ pi ^ + \ pi ^ - ) $ is determined by the branching fractions of $ \ lambda ^ + _ c \ to \ delta ^ { + + } k ^ - $, $ \ lambda ^ + _ c \ to \ delta ^ { + } k ^ 0 _ { s, l } $ and $ \ lambda ^ + _ c \ to \ delta ^ { 0 } k ^ + $ modes under the isospin symmetry. the ambiguities from loop - induced quantities and $ su ( 3 ) _ f $ breaking hadronic effects are avoided. once the $ cp $ asymmetry in the $ \ lambda _ c ^ + $ decays into $ \ delta ^ + $ and neutral kaons is confirmed by experiments, we can check if it is beyond the standard model, or verify the $ cp $ - violating effect resulted from the interference between the cabibbo - favored and the doubly cabibbo - suppressed amplitudes with the neutral kaon mixing. future measurements of branching fractions play a critical role in reducing the uncertainties.
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arxiv:2204.04116
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we study the problem of existence of finite energy monopole solutions in the weinberg - salam model starting with a most general ansatz for static axially - symmetric electroweak magnetic fields. the ansatz includes an explicit construction of field configurations with various topologies described by the monopole and hopf charges. we introduce a unique su ( 2 ) gauge invariant definition for the electromagnetic field. it has been proved that the magnetic charge of any finite energy monopole solution must be screened at far distance. this implies non - existence of finite energy monopole solutions with a non - zero total magnetic charge. in a case of a special axially - symmetric dashen - hasslacher - neveu ansatz we revise the structure of the sphaleron solution and show that sphaleron represents a non - trivial system of monopole and antimonopole with their centers located in one point. this is different from the known interpretation of the sphaleron as a monopole - antimonopole pair like nambu ' s " dumb - bell ". in general, the axially - symmetric magnetic field may admit a helical structure. we conjecture that such a solution exists and estimate an upper bound for its energy, e _ { bound } = 4. 65 tev.
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arxiv:1311.7567
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we report the experimental findings of formation and motion of heap in granular materials in an inclined and vertically vibrated container. we show experimentally how the transport velocity of heap up container is related to the driving acceleration as well as the driving frequency of exciter. an analogous experiment was performed with a heap - shaped plexiglas block. we propose that cohesion force resulted from pressure gradient in ambient gas plays a crucial role in enhancing and maintaining a heap, and ratchet effect causes the movement of the heap. an equation which governs the transport velocity of the heap is presented.
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arxiv:cond-mat/0511693
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current vertex correction ( cvc ), the back - flow - like correction to the current, comes from conservation laws, and the cvc due to electron correlation contains information about many - body effects. however, it has been little understood how the cvc due to electron correlation affects the charge transports of a correlated multiorbital system. to improve this situation, i studied the inplane resistivity, $ \ rho _ { ab } $, and the hall coefficient in the weak - field limit, $ r _ { \ textrm { h } } $, in addition to the magnetic properties and the electronic structure, for a $ t _ { 2g } $ - orbital hubbard model on a square lattice in a paramagnetic state away from or near an antiferromagnetic ( af ) quantum - critical point ( qcp ) in the fluctuation - exchange ( flex ) approximation with the cvcs arising from the self - energy ( $ \ sigma $ ), the maki - thompson ( mt ) irreducible four - point vertex function, and the main terms of the aslamasov - larkin ( al ) one. then, i found three main results about the cvcs. first, the main terms of the al cvc does not qualitatively change the results obtained in the flex approximation with the $ \ sigma $ cvc and the mt cvc. second, $ \ rho _ { ab } $ and $ r _ { \ textrm { h } } $ near the af qcp have high - temperature region, governed mainly by the $ \ sigma $ cvc, and low - temperature region, governed mainly by the $ \ sigma $ cvc and the mt cvc. third, in case away from the af qcp, the mt cvc leads to a considerable effect on only $ r _ { \ textrm { h } } $ at low temperatures, although $ r _ { \ textrm { h } } $ at high temperatures and $ \ rho _ { ab } $ at all temperatures considered are sufficiently described by including only the $ \ sigma $ cvc. i also achieved the qualitative agreement with several experiments of sr $ _ { 2 } $ ruo $ _ { 4 } $ or sr $ _ { 2 } $ ru $ _ { 0. 975 } $ ti $ _ { 0. 025 } $ o $ _ { 4 } $. moreover, i showed several better points of this theory than other theories.
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arxiv:1505.05274
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we determine the detailed structure of parabolic subgroups of orthogonal groups over $ \ mathbb { z } $, and deduce the precise form of canonical boundary components in toroidal compactifications of orthogonal shimura varieties.
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arxiv:1902.08264
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in this note we examine certain classes of solutions of iia theory without sources, of the form ads $ _ 2 \ times { \ cal m } ^ { ( 1 ) } \ times \ dots \ times { \ cal m } ^ { ( n ) } $, where $ { \ cal m } ^ { ( i ) } $ are riemannian spaces. we show that large hierarchies of curvatures can be obtained between the different factors, however the absolute value of the scalar curvature of ads $ _ 2 $ must be of the same order or larger than the absolute values of the scalar curvatures of all the other factors.
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arxiv:2004.07582
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the riesz potential $ f _ s ( r ) = r ^ { - s } $ is known to be an important building block of many interactions, including lennard - jones type potentials $ f _ { n, m } ^ { \ rm { lj } } ( r ) : = a r ^ { - n } - b r ^ { - m } $, $ n > m $ that are widely used in molecular simulations. in this paper, we investigate analytically and numerically the minimizers among three - dimensional lattices of riesz and lennard - jones energies. we discuss the minimality of the body - centred - cubic lattice ( bcc ), face - centred - cubic lattice ( fcc ), simple hexagonal lattices ( sh ) and hexagonal close - packing structure ( hcp ), globally and at fixed density. in the riesz case, new evidence of the global minimality at fixed density of the bcc lattice is shown for $ s < 0 $ and the hcp lattice is computed to have higher energy than the fcc ( for $ s > 3 / 2 $ ) and bcc ( for $ s < 3 / 2 $ ) lattices. in the lennard - jones case with exponents $ 3 < m < n $, the ground state among lattices is confirmed to be a fcc lattice whereas a hcp phase occurs once added to the investigated structures. furthermore, phase transitions of type ` ` fcc - sh " and ` ` fcc - hcp - sh " ( when the hcp lattice is added ) as the inverse density $ v $ increases are observed for a large spectrum of exponents $ ( n, m ) $. in the sh phase, the variation of the ratio $ \ delta $ between the inter - layer distance $ d $ and the lattice parameter $ a $ is studied as $ v $ increases. in the critical region of exponents $ 0 < m < n < 3 $, the sh phase with an extreme value of the anisotropy parameter $ \ delta $ dominates. if one limits oneself to rigid lattices, the bcc - fcc - hcp phase diagram is found. for $ - 2 < m < n < 0 $, the bcc lattice is the only energy minimizer. choosing $ - 4 < m < n < - 2 $, the fcc and sh latices become minimizers.
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arxiv:2107.14020
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we review the standard model in a form conducive to formulating its possible short distance extensions. this depends on the value of the higgs mass, the only unknown parameter of the model. we suggest methods to reproduce many of the small numbers in the model in terms of scale ratios, applying see - saw like ideas to the breaking of chiral symmetries. we then investigate how the $ n = 1 $ standard model extrapolated to or near the planck scale can fit superstring models, emphasizing the use of some non - renormalizable operators generic to superstrings.
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arxiv:hep-ph/9412387
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we demonstrate electrical injection and detection of spin - polarized electrons in silicon ( si ) using epitaxially grown fe _ 3si / si schottky - tunnel - barrier contacts. by an insertion of a delta - doped n ^ + - si layer ( ~ 10 ^ 19 cm ^ - 3 ) near the interface between a ferromagnetic fe _ 3si / si contact and a si channel ( ~ 10 ^ 15 cm ^ - 3 ), we achieve a marked enhancement in the tunnel conductance for reverse - bias characteristics of the fe _ 3si / si schottky diodes. using laterally fabricated four - probe geometries with the modified fe _ 3si / si contacts, we detect nonlocal output signals which originate from the spin accumulation in a si channel at low temperatures.
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arxiv:0904.2980
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this paper is a continuation of " quantization of lie bialgebras, i " ( q - alg / 9606005 ). we show that the quantization procedure defined in " quantization of lie bialgebras, i " is given by universal acyclic formulas and defines a functor from the category of lie bialgebras to the category of quantized universal enveloping algebras. we also show that this functor defines an equivalence between the category of lie bialgebras over k [ [ h ] ] and the category quantized universal enveloping ( que ) algebras.
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arxiv:q-alg/9701038
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the goal of this article is to display a $ q $ - polynomial structure for the attenuated space poset $ \ mathcal a _ q ( n, m ) $. the poset $ \ mathcal a _ q ( n, m ) $ is briefly described as follows. start with an $ ( n + m ) $ - dimensional vector space $ h $ over a finite field with $ q $ elements. fix an $ m $ - dimensional subspace $ h $ of $ h $. the vertex set $ x $ of $ \ mathcal a _ q ( n, m ) $ consists of the subspaces of $ h $ that have zero intersection with $ h $. the partial order on $ x $ is the inclusion relation. the $ q $ - polynomial structure involves two matrices $ a, a ^ * \ in { \ rm mat } _ x ( \ mathbb c ) $ with the following entries. for $ y, z \ in x $ the matrix $ a $ has $ ( y, z ) $ - entry $ 1 $ ( if $ y $ covers $ z $ ) ; $ q ^ { { \ rm dim } \, y } $ ( if $ z $ covers $ y $ ) ; and 0 ( if neither of $ y, z $ covers the other ). the matrix $ a ^ * $ is diagonal, with $ ( y, y ) $ - entry $ q ^ { - { \ rm dim } \, y } $ for all $ y \ in x $. by construction, $ a ^ * $ has $ n + 1 $ eigenspaces. by construction, $ a $ acts on these eigenspaces in a ( block ) tridiagonal fashion. we show that $ a $ is diagonalizable, with $ 2n + 1 $ eigenspaces. we show that $ a ^ * $ acts on these eigenspaces in a ( block ) tridiagonal fashion. using this action, we show that $ a $ is $ q $ - polynomial. we show that $ a, a ^ * $ satisfy a pair of relations called the tridiagonal relations. we consider the subalgebra $ t $ of $ { \ rm mat } _ x ( \ mathbb c ) $ generated by $ a, a ^ * $. we show that $ a, a ^ * $ act on each irreducible $ t $ - module as a leonard pair.
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arxiv:2307.07833
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magnetic topological insulators ( mti ) constitute a novel class of materials where the topologically protected band structure coexists with long - range ferromagnetic order, which can lead to the breaking of time - reversal symmetry ( trs ), introducing a bandgap in the dirac cone - shaped topological surface state ( tss ). the gap opening in mits has been predicted to be accompanied by a distortion in the tss, evolving its warped shape from hexagonal to trigonal. in this work, we demonstrate such a transition by means of angle - resolved photoemission spectroscopy after the deposition of low concentrations of magnetic rare earths, namely er and dy, on the ternary three - dimensional prototypical topological insulator bi $ _ 2 $ se $ _ 2 $ te. signatures of the gap opening occurring as a consequence of the trs breaking have also been observed, whose existence is supported by the observation of the aforementioned transition. moreover, increasing the er coverage results in a tunable p - type doping of the tss. as a consequence, the fermi level ( e $ _ { \ textrm { f } } $ ) of our bi $ _ 2 $ se $ _ 2 $ te crystals can be gradually tuned towards the tss dirac point, and therefore to the magnetically induced bandgap ; thus fulfilling two of the necessary prerequisites for the realization of the quantum anomalous hall effect ( qahe ) in this system. the experimental results are rationalized by a theoretical model where a magnetic zeeman out - of - plane term is introduced in the hamiltonian governing the tss band dispersion. our results offer new strategies to control magnetic interactions with tsss based on a simple approach and open up viable routes for the realization of the qahe.
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arxiv:2302.01684
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high - capacity image steganography, aimed at concealing a secret image in a cover image, is a technique to preserve sensitive data, e. g., faces and fingerprints. previous methods focus on the security during transmission and subsequently run a risk of privacy leakage after the restoration of secret images at the receiving end. to address this issue, we propose a framework, called multitask identity - aware image steganography ( miais ), to achieve direct recognition on container images without restoring secret images. the key issue of the direct recognition is to preserve identity information of secret images into container images and make container images look similar to cover images at the same time. thus, we introduce a simple content loss to preserve the identity information, and design a minimax optimization to deal with the contradictory aspects. we demonstrate that the robustness results can be transferred across different cover datasets. in order to be flexible for the secret image restoration in some cases, we incorporate an optional restoration network into our method, providing a multitask framework. the experiments under the multitask scenario show the effectiveness of our framework compared with other visual information hiding methods and state - of - the - art high - capacity image steganography methods.
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arxiv:2107.05819
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control of network systems with uncertain local dynamics has remained an open problem for a long time. in this paper, a distributed minimax adaptive control algorithm is proposed for such networks whose local dynamics has an uncertain parameter possibly taking finite number of values. to hedge against this uncertainty, each node in the network collects the historical data of its neighboring nodes to decide its control action along its edges by finding the parameter that best describes the observed disturbance trajectory. our proposed distributed adaptive controller is scalable and we give both lower and upper bounds for its $ \ ell _ { 2 } $ gain. numerical simulations demonstrate that once each node has sufficiently estimated its local uncertainty, the distributed minimax adaptive controller behaves like the optimal distributed $ \ mathcal { h } _ { \ infty } $ controller in hindsight.
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arxiv:2310.17364
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the problem of computing sum of sources over a multiple access channel ( mac ) is considered. building on the technique of linear computation coding ( lcc ) proposed by nazer and gastpar [ 2007 ], we employ the ensemble of nested coset codes to derive a new set of sufficient conditions for computing the sum of sources over an \ textit { arbitrary } mac. the optimality of nested coset codes [ padakandla, pradhan 2011 ] enables this technique outperform lcc even for linear mac with a structural match. examples of nonadditive mac for which the technique proposed herein outperforms separation and systematic based computation are also presented. finally, this technique is enhanced by incorporating separation based strategy, leading to a new set of sufficient conditions for computing the sum over a mac.
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arxiv:1301.5684
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object detection has been a challenging task in computer vision. although significant progress has been made in object detection with deep neural networks, the attention mechanism is far from development. in this paper, we propose the hybrid attention mechanism for single - stage object detection. first, we present the modules of spatial attention, channel attention and aligned attention for single - stage object detection. in particular, stacked dilated convolution layers with symmetrically fixed rates are constructed to learn spatial attention. the channel attention is proposed with the cross - level group normalization and squeeze - and - excitation module. aligned attention is constructed with organized deformable filters. second, the three kinds of attention are unified to construct the hybrid attention mechanism. we then embed the hybrid attention into retina - net and propose the efficient single - stage har - net for object detection. the attention modules and the proposed har - net are evaluated on the coco detection dataset. experiments demonstrate that hybrid attention can significantly improve the detection accuracy and the har - net can achieve the state - of - the - art 45. 8 \ % map, outperform existing single - stage object detectors.
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arxiv:1904.11141
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an effective, reliable and time saving numerical method with using of the pruefer transformation is proposed to calculate eigenvalues of chandrasekhar - page angular equations.
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arxiv:1605.07450
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symmetries are prevalent in deep learning and can significantly influence the learning dynamics of neural networks. in this paper, we examine how exponential symmetries - - a broad subclass of continuous symmetries present in the model architecture or loss function - - interplay with stochastic gradient descent ( sgd ). we first prove that gradient noise creates a systematic motion ( a ` ` noether flow " ) of the parameters $ \ theta $ along the degenerate direction to a unique initialization - independent fixed point $ \ theta ^ * $. these points are referred to as the { \ it noise equilibria } because, at these points, noise contributions from different directions are balanced and aligned. then, we show that the balance and alignment of gradient noise can serve as a novel alternative mechanism for explaining important phenomena such as progressive sharpening / flattening and representation formation within neural networks and have practical implications for understanding techniques like representation normalization and warmup.
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arxiv:2402.07193
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to address the limitations of current hate speech detection models, we introduce \ textsf { sghatecheck }, a novel framework designed for the linguistic and cultural context of singapore and southeast asia. it extends the functional testing approach of hatecheck and mhc, employing large language models for translation and paraphrasing into singapore ' s main languages, and refining these with native annotators. \ textsf { sghatecheck } reveals critical flaws in state - of - the - art models, highlighting their inadequacy in sensitive content moderation. this work aims to foster the development of more effective hate speech detection tools for diverse linguistic environments, particularly for singapore and southeast asia contexts.
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arxiv:2405.01842
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we generalize the work of deser and levin on the unified description of hawking radiation and unruh effect to general stationary motions in spherically symmetric black holes. we have also matched the chemical potential term of the thermal spectrum of the two sides for uncharged black holes.
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arxiv:gr-qc/0409107
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we report the results of $ easycritics $, a fully automated algorithm for the efficient search of strong - lensing ( sl ) regions in wide - field surveys, applied to the canada - france - hawaii telescope lensing survey ( cfhtlens ). by using only the photometric information of the brightest elliptical galaxies distributed over a wide redshift range ( $ \ smash { 0. 2 \ lesssim z \ lesssim 0. 9 } $ ) and without requiring the identification of arcs, our algorithm produces lensing potential models and catalogs of critical curves of the entire survey area. we explore several parameter set configurations in order to test the efficiency of our approach. in a specific configuration, $ easycritics $ generates only $ \ sim1200 $ possibly super - critical regions in the cfhtls area, drastically reducing the effective area for inspection from $ 154 $ sq. deg to $ \ sim0. 623 $ sq. deg, $ i. e. $ by more than two orders of magnitude. among the pre - selected sl regions, we identify 32 of the 44 previously known lenses on the group and cluster scale, and discover 9 new promising lens candidates. the detection rate can be easily improved to $ \ sim82 \ % $ by a simple modification in the parameter set, but at the expense of increasing the total number of possible sl candidates. note that $ easycritics $ is fully complementary to other arc - finders since we characterize lenses instead of directly identifying arcs. although future comparisons against numerical simulations are required for fully assessing the efficiency of $ easycritics $, the algorithm seems very promising for upcoming surveys covering $ \ smash { 10 ^ { 4 } } $ sq. deg, such as the $ euclid $ mission and $ lsst $, where the pre - selection of candidates for any kind of sl analysis will be indispensable due to the expected enormous data volume.
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arxiv:1807.03793
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a traditional stochastic program under a finite population typically seeks to optimize efficiency by maximizing the expected profits or minimizing the expected costs, subject to a set of constraints. however, implementing such optimization - based decisions can have varying impacts on individuals, and when assessed using the individuals ' utility functions, these impacts may differ substantially across demographic groups delineated by sensitive attributes, such as gender, race, age, and socioeconomic status. as each group comprises multiple individuals, a common remedy is to enforce group fairness, which necessitates the measurement of disparities in the distributions of utilities across different groups. this paper introduces the concept of distributionally fair stochastic optimization ( dfso ) based on the wasserstein fairness measure. the dfso aims to minimize distributional disparities among groups, quantified by the wasserstein distance, while adhering to an acceptable level of inefficiency. our analysis reveals that : ( i ) the wasserstein fairness measure recovers the demographic parity fairness prevalent in binary classification literature ; ( ii ) this measure can approximate the well - known kolmogorov - smirnov fairness measure with considerable accuracy ; and ( iii ) despite dfso ' s biconvex nature, the epigraph of the wasserstein fairness measure is generally mixed - integer convex programming representable ( micp - r ). additionally, we introduce two distinct lower bounds for the wasserstein fairness measure : the jensen bound, applicable to the general wasserstein fairness measure, and the gelbrich bound, specific to the type - 2 wasserstein fairness measure. we establish the exactness of the gelbrich bound and quantify the theoretical difference between the wasserstein fairness measure and the gelbrich bound.
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arxiv:2402.01872
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we consider mean - field control problems in discrete time with discounted reward, infinite time horizon and compact state and action space. the existence of optimal policies is shown and the limiting mean - field problem is derived when the number of individuals tends to infinity. moreover, we consider the average reward problem and show that the optimal policy in this mean - field limit is $ \ varepsilon $ - optimal for the discounted problem if the number of individuals is large and the discount factor close to one. this result is very helpful, because it turns out that in the special case when the reward does only depend on the distribution of the individuals, we obtain a very interesting subclass of problems where an average reward optimal policy can be obtained by first computing an optimal measure from a static optimization problem and then achieving it with markov chain monte carlo methods. we give two applications : avoiding congestion an a graph and optimal positioning on a market place which we solve explicitly.
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arxiv:2106.08755
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d0 has used w - > e nu events produced in association with a high $ p _ t $ jet to examine the effects of strong radiative corrections. we have compared the primary jet pseudorapidity distribution, as a function of reconstructed w rapidity to leading order ( lo ) and next to leading order ( nlo ) qcd monte carlos, as well as a model based on extended color dipoles. our preliminary analysis finds that the primary jet is more central than either lo or nlo expectations and is in qualitative agreement with the color dipole model.
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arxiv:hep-ex/9412002
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recently an operator space version of type and cotype, namely type $ ( p, h ) $ and cotype $ ( q, h ) $ of operator spaces for $ 1 \ leq p \ leq 2 \ leq q \ leq \ infty $ and a subquadratic and homogeneous hilbetian operator space $ h $ were introduced and investigated by the author. in this paper we define weak type $ ( 2, h ) $ ( resp. weak cotype $ ( 2, h ) $ ) of operator spaces, which lies strictly between type $ ( 2, h ) $ ( resp. cotype $ ( 2, h ) $ ) and type $ ( p, h ) $ for all $ 1 \ leq p < 2 $ ( resp. cotype $ ( q, h ) $ for all $ 2 < q \ leq \ infty $ ). this is an analogue of weak type 2 and weak cotype 2 in the banach space case, so we develop analogous equivalent formulations. we also consider weak - $ h $ space, spaces with weak type $ ( 2, h ) $ and weak cotype $ ( 2, h ^ * ) $ simultaneously and establish corresponding equivalent formulations.
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arxiv:math/0502337
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neutron electric dipole moment ( nedm ), a generic feature of cp - violation, is predicted to be very small in the standard model, but can be much larger in most extensions of the model. in this talk, i will discuss the classification of the cp violating operators up to dimension 6 that can give rise to nedm, and then describe the mixing and renormalization structure of the operators of dimension 5 and lower in both dimensional and cutoff regularizations in general terms. finally i will describe how to connect the dimension 5 operators, in particular, the chromoelectric dipole moment of the quarks, between msbar scheme and a regularization independent prescription in the chiral limit.
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arxiv:1403.2445
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the term { \ em complexity } is used informally both as a quality and as a quantity. as a quality, complexity has something to do with our ability to understand a system or object - - we understand simple systems, but not complex ones. on another level, { \ em complexity } is used as a quantity, when we talk about something being more complicated than another. in this chapter, we explore the formalisation of both meanings of complexity, which happened during the latter half of the twentieth century.
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arxiv:0805.0685
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we present a theoretical study of heat transport in electrically insulating ferromagnetic wires containing a domain wall. in the regime of validity of continuum micromagnetism a domain wall is found to have no effect on the heat conductance. however, spin waves are found to be reflected by domain walls with widths of a few lattice spacings, which is associated with emergence of an additional spin wave bound state. the resulting domain wall heat conductance should be significant for thin films of yttrium iron garnet with sharply defined magnetic domains.
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arxiv:1204.4008
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the study of shell - type supernova remnants is a key science focus for the veritas tev telescope array. supernova remnants ( snrs ) are widely considered to be the strongest candidate for the source of cosmic rays below the knee around 10 ^ 15 ev. this presentation will highlight new veritas results including new measurements of the spectra of cas a and ic 443 and observations of the " forbidden velocity wing " fvw 190. 2 + 1. 1. these results and their implications for the nature of the cosmic rays - hadronic or electronic - accelerated in the remnants will be discussed.
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arxiv:0907.5018
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using chandra acis - s, we have obtained imaging xray spectrophotometry of the pluto system in support of the new horizons flyby on 14 july 2015. 174 ksec of observations were obtained on 4 visits in feb 2014 to aug 2015. we measured a net signal of 6. 8 counts and a noise level of 1. 2 counts in a comoving 11 x 11 pixel box ( 100 x 100 r _ pluto ) in the 0. 31 to 0. 60 kev passband for a detection at > 99. 95 c. l. the pluto photons do not match the background spectrum, are coincident with a 90 % flux aperture comoving with pluto, and are not sky source confused. the mean 0. 31 to 0. 60 kev xray power from pluto is 200 mw, in the midrange of xray power levels seen for known solar system emission sources : auroral precipitation, solar xray scattering, and charge exchange ( cxe ) between solar wind ( sw ) ions & atmospheric neutrals. we eliminate auroral effects as a source, as pluto has no known magnetic field & the new horizons alice uv spectrometer detected no airglow from pluto during the flyby. nano - scale atmospheric haze particles could lead to enhanced resonant scattering of solar x - rays from pluto, but the energy signature of the detected photons does not match the solar spectrum and estimates of plutos scattered xray emission are > 100 times below the 3. 9e - 5 cps found in our observations. cxe emission from sw carbon, nitrogen, and oxygen ions can produce the energy signature seen, and the 6e25 neutral gas escape rate from pluto deduced from new horizons data can support the 3. 0e24 xray photons / sec emission rate required by our observations. using the sw proton density and speed measured by the solar wind around pluto ( swap ) instrument in the vicinity of pluto at the time of the photon emissions, we find too few sw minor ions flowing into the 11 x 11 pixel box centered on pluto than are needed to support the observed emission rate unless the sw is significantly focused and enhanced in this region.
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arxiv:1610.07963
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in the modern world, the development of artificial intelligence ( ai ) has contributed to improvements in various areas, including automation, computer vision, fraud detection, and more. ai can be leveraged to enhance the efficiency of autonomous smart traffic management ( astm ) systems and reduce traffic congestion rates. this paper presents an autonomous smart traffic management ( stm ) system that uses ai to improve traffic flow rates. the system employs the yolo v5 convolutional neural network to detect vehicles in traffic management images. additionally, it predicts the number of vehicles for the next 12 hours using a recurrent neural network with long short - term memory ( rnn - lstm ). the smart traffic management cycle length analysis manages the traffic cycle length based on these vehicle predictions, aided by ai. from the results of the rnn - lstm model for predicting vehicle numbers over the next 12 hours, we observe that the model predicts traffic with a mean squared error ( mse ) of 4. 521 vehicles and a root mean squared error ( rmse ) of 2. 232 vehicles. after simulating the stm system in the carla simulation environment, we found that the traffic management congestion flow rate with astm ( 21 vehicles per minute ) is 50 \ % higher than the rate without stm ( around 15 vehicles per minute ). additionally, the traffic management vehicle pass delay with stm ( 5 seconds per vehicle ) is 70 \ % lower than without stm ( around 12 seconds per vehicle ). these results demonstrate that the stm system using ai can increase traffic flow by 50 \ % and reduce vehicle pass delays by 70 \ %.
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arxiv:2410.10929
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in the last decades, light detection and ranging ( lidar ) technology has been extensively explored as a robust alternative for self - localization and mapping. these approaches typically state ego - motion estimation as a non - linear optimization problem dependent on the correspondences established between the current point cloud and a map, whatever its scope, local or global. this paper proposes liodom, a novel lidar - only odometry and mapping approach for pose estimation and map - building, based on minimizing a loss function derived from a set of weighted point - to - line correspondences with a local map abstracted from the set of available point clouds. furthermore, this work places a particular emphasis on map representation given its relevance for quick data association. to efficiently represent the environment, we propose a data structure that combined with a hashing scheme allows for fast access to any section of the map. liodom is validated by means of a set of experiments on public datasets, for which it compares favourably against other solutions. its performance on - board an aerial platform is also reported.
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arxiv:2111.03393
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recurrence plot ( rp ) and recurrence quantification analysis rqa ) are signal numerical analysis methodologies able to work with non linear dynamical systems and non stationarity. moreover they well evidence changes in the states of a dynamical system. it is shown that rp and rqa detect the critical regime in financial indices ( in analogy with phase transition ) before a bubble bursts, whence allowing to estimate the bubble initial time. the analysis is made on nasdaq daily closing price between jan. 1998 and nov. 2003. the nasdaq bubble initial time has been estimated to be on oct. 19, 1999.
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arxiv:physics/0505170
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object - oriented data analysis is a fascinating and evolving field in modern statistical science, with the potential to make significant contributions to biomedical applications. this statistical framework facilitates the development of new methods to analyze complex data objects that capture more information than traditional clinical biomarkers. this paper applies the object - oriented framework to analyze physical activity levels, measured by accelerometers, as response objects in a regression model. unlike traditional summary metrics, we utilize a recently proposed representation of physical activity data as a distributional object, providing a more nuanced and complete profile of individual energy expenditure across all ranges of monitoring intensity. a novel hybrid fr \ ' echet regression model is proposed and applied to us population accelerometer data from national health and nutrition examination survey ( nhanes ) 2011 - 2014. the semi - parametric nature of the model allows for the inclusion of nonlinear effects for critical variables, such as age, which are biologically known to have subtle impacts on physical activity. simultaneously, the inclusion of linear effects preserves interpretability for other variables, particularly categorical covariates such as ethnicity and sex. the results obtained are valuable from a public health perspective and could lead to new strategies for optimizing physical activity interventions in specific american subpopulations.
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arxiv:2302.07692
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we propose a novel linearization of a constituent tree, together with a new locally normalized model. for each split point in a sentence, our model computes the normalizer on all spans ending with that split point, and then predicts a tree span from them. compared with global models, our model is fast and parallelizable. different from previous local models, our linearization method is tied on the spans directly and considers more local features when performing span prediction, which is more interpretable and effective. experiments on ptb ( 95. 8 f1 ) and ctb ( 92. 4 f1 ) show that our model significantly outperforms existing local models and efficiently achieves competitive results with global models.
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arxiv:2004.14704
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a uniaxial strain applied to graphene - like materials moves the dirac nodes along the boundary of the brillouin zone. an extreme case is the merging of the dirac node positions to a single degenerate spectral node which gives rise to a new topological phase. then isotropic dirac nodes are replaced by a node with a linear behavior in one and a parabolic behavior in the other direction. this anisotropy influences substantially the optical properties. we propose a method to determine characteristic spectral and transport properties in black phosphorus layers which were recently studied by several groups with angle - resolved photoemission spectroscopy, and discuss how the transmittance, the reflectance and the optical absorption of this material can be tuned. in particular, we demonstrate that the transmittance of linearly polarized incident light varies from nearly 0 \ % to almost 100 \ % in the microwave and far - infrared regime.
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arxiv:1712.08529
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smb6 exhibits intermediate valence in the ground state and unusual behaviour at low temperatures. the resistivity and the hall effect cannot be explained either by conventional sf - hybridization or by hopping transport in an impurity band. at least three different energy scales determine three temperature regimes of electron transport in this system. we consider the ground state properties, the soft valence fluctuations and the spectrum of band carriers in n - doped smb6. the behaviour of excess conduction electrons in the presence of soft valence fluctuations and the origin of the three energy scales in the spectrum of elementary excitations is discussed. the carriers which determine the low - temperature transport in this system are self - trapped electron - polaron complexes rather than simply electrons in an impurity band. the mechanism of electron trapping is the interaction with soft valence fluctuations.
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arxiv:cond-mat/9911266
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a foundational requirement of a deployed ml model is to generalize to data drawn from a testing distribution that is different from training. a popular solution to this problem is to adapt a pre - trained model to novel domains using only unlabeled data. in this paper, we focus on a challenging variant of this problem, where access to the original source data is restricted. while fully test - time adaptation ( ftta ) and unsupervised domain adaptation ( uda ) are closely related, the advances in uda are not readily applicable to tta, since most uda methods require access to the source data. hence, we propose a new approach, cattan, that bridges uda and ftta, by relaxing the need to access entire source data, through a novel deep subspace alignment strategy. with a minimal overhead of storing the subspace basis set for the source data, cattan enables unsupervised alignment between source and target data during adaptation. through extensive experimental evaluation on multiple 2d and 3d vision benchmarks ( imagenet - c, office - 31, officehome, domainnet, pointda - 10 ) and model architectures, we demonstrate significant gains in ftta performance. furthermore, we make a number of crucial findings on the utility of the alignment objective even with inherently robust models, pre - trained vit representations and under low sample availability in the target domain.
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arxiv:2207.04185
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ascribing the large su ( 3 ) violations in the cabibbo forbidden decays of neutral d mesons to the final state interactions, one gets large strong phase differences, necessary for substantial direct cp violation. while the absolute value of the cp violating asymmetries depend on the uncertain strength of the penguin contribution, we predict an asymmetry for the decays into charged pions more than twice as large and having opposite sign with respect to that for charged kaons.
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arxiv:1305.7343
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in a friedmann - robertson - walker ( frw ) space - time background we study the classical cosmological models in the context of recently proposed theory of nonlinear minimal massive bigravity. we show that in the presence of perfect fluid the classical field equations acquire contribution from the massive graviton as a cosmological term which is positive or negative depending on the dynamical competition between two scale factors of bigravity metrics. we obtain the classical field equations for flat and open universes in the ordinary and schutz representation of perfect fluid. focusing on the schutz representation for flat universe, we find classical solutions exhibiting singularities at early universe with vacuum equation of state. then, in the schutz representation, we study the quantum cosmology for flat universe and derive the schrodinger - wheeler - dewitt equation. we find its exact and wave packet solutions and discuss on their properties to show that the initial singularity in the classical solutions can be avoided by quantum cosmology. similar to the study of hartle - hawking no - boundary proposal in the quantum cosmology of de rham, gabadadze and tolley ( drgt ) massive gravity, it turns out that the mass of graviton predicted by quantum cosmology of the minimal massive bigravity is large at early universe. this is in agreement with the fact that at early universe the cosmological constant should be large.
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arxiv:1512.03333
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we present analytical results for the distribution of cover times of random walks ( rws ) on random regular graphs consisting of $ n $ nodes of degree $ c $ ( $ c \ ge 3 $ ). starting from a random initial node at time $ t = 1 $, at each time step $ t \ ge 2 $ an rw hops into a random neighbor of its previous node. in some of the time steps the rw may visit a new, yet - unvisited node, while in other time steps it may revisit a node that has already been visited before. the cover time $ t _ { \ rm c } $ is the number of time steps required for the rw to visit every single node in the network at least once. we derive a master equation for the distribution $ p _ t ( s = s ) $ of the number of distinct nodes $ s $ visited by an rw up to time $ t $ and solve it analytically. inserting $ s = n $ we obtain the cumulative distribution of cover times, namely the probability $ p ( t _ { \ rm c } \ le t ) = p _ t ( s = n ) $ that up to time $ t $ an rw will visit all the $ n $ nodes in the network. taking the large network limit, we show that $ p ( t _ { \ rm c } \ le t ) $ converges to a gumbel distribution. we calculate the distribution of partial cover ( pc ) times $ p ( t _ { { \ rm pc }, k } = t ) $, which is the probability that at time $ t $ an rw will complete visiting $ k $ distinct nodes. we also calculate the distribution of random cover ( rc ) times $ p ( t _ { { \ rm rc }, k } = t ) $, which is the probability that at time $ t $ an rw will complete visiting all the nodes in a subgraph of $ k $ randomly pre - selected nodes at least once. the analytical results for the distributions of cover times are found to be in very good agreement with the results obtained from computer simulations.
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arxiv:2110.13592
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the quasiparticle scattering interference phenomenon characterized by the peaks in the local density of states is studied within the kinetic energy driven superconducting mechanism in the presence of a single impurity. by calculation of the fourier transformed ratio of the local density of states at opposite energy, it is shown that the quasiparticle scattering interference phenomenon can be described qualitatively by a single impurity in the kinetic energy driven homogeneous d - wave superconducting state. the amplitude of the peak increases with increasing energy at the low energy, and reaches a maximum at the intermediate energy, then diminishes to zero at the high energy. the theory also predicts that with increasing doping, the position of the peak along the nodal direction moves towards to the center of the brillouin zone, while the position of the peak along the antinodal direction is shifted to large momentum region.
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arxiv:1001.3232
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near or less than 10 % nb substitution on the ti site in perovskite srtio $ _ 3 $ results in metallic behavior, in contrast to what is seen in batio $ _ 3 $. given the nearly identical structure and electron counts of the two materials, the distinct ground states for low substitution have been a long - standing puzzle. here we find from neutron studies of average and local structure, the subtle yet critical difference that we believe underpins the distinct electronic properties in these fascinating materials. while srti $ _ { 0. 875 } $ nb _ $ { 0. 125 } $ o $ _ 3 $ possesses a distorted non - cubic structure at 15 k, the bo $ _ 6 $ octahedra in the structure are regular. bati $ _ { 0. 875 } $ nb $ _ { 0. 125 } $ o $ _ 3 $ on the other hand shows evidence for local cation off - centering whilst retaining a cubic structure.
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arxiv:0808.1308
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within the framework of the color flux - tube model with a multibody confinement potential, we systematically investigate the hidden charmed states observed in recent years. it can be found that most of them can be described as the compact tetraquark states $ [ cq ] [ \ bar { c } \ bar { q } ] $ ( $ q = u, d $ and $ s $ ) in the color flux - tube model. the multibody confinement potential based on the color flux - tube picture is a dynamical mechanism in the formation and decay of the compact tetraquark states.
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arxiv:1801.00164
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in this research paper, we investigate into a paper named " a deep reinforcement learning framework for the financial portfolio management problem " [ arxiv : 1706. 10059 ]. it is a portfolio management problem which is solved by deep learning techniques. the original paper proposes a financial - model - free reinforcement learning framework, which consists of the ensemble of identical independent evaluators ( eiie ) topology, a portfolio - vector memory ( pvm ), an online stochastic batch learning ( osbl ) scheme, and a fully exploiting and explicit reward function. three different instants are used to realize this framework, namely a convolutional neural network ( cnn ), a basic recurrent neural network ( rnn ), and a long short - term memory ( lstm ). the performance is then examined by comparing to a number of recently reviewed or published portfolio - selection strategies. we have successfully replicated their implementations and evaluations. besides, we further apply this framework in the stock market, instead of the cryptocurrency market that the original paper uses. the experiment in the cryptocurrency market is consistent with the original paper, which achieve superior returns. but it doesn ' t perform as well when applied in the stock market.
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arxiv:2409.08426
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the angular distribution of the emitted electrons, following the two - - photon ionization of the hydrogen - - like ions, is studied within the framework of second order perturbation theory \ textit { and } the dirac equation. using a density matrix approach, we have investigated the effects which arise from the polarization of the incoming light as well as from the higher multipoles in the expansion of the electron - - photon interaction. for medium - - and high - - z ions, in particular, the non - - dipole contributions give rise to a significant change in the angular distribution of the emitted electrons, if compared with the electric - - dipole approximation. this includes a strong forward emission while, in dipole approximation, the electron emission always occurs symmetric with respect to the plane which is perpendicular to the photon beam. detailed computations for the dependence of the photoelectron angular distributions on the polarization of the incident light are carried out for the ionization of the h, xe $ ^ { 53 + } $ and u $ ^ { 91 + } $ ( hydrogen - - like ) ions.
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arxiv:physics/0312111
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the h. e. s. s. galactic plane survey has detected very - high - energy ( vhe ) gamma - ray emission from 78 sources in the milky way. these sources belong to different object classes ( pulsar wind nebulae, supernova remnants or binary systems ) and some of these sources remain unidentified. the gamma - ray emission of these objects may be of leptonic or hadronic origin and gamma - ray observations alone cannot distinguish between these two scenarios. the detection of neutrino emission would provide evidence for a hadronic scenario in these objects. based on the observed gamma - ray spectra we predict the neutrino emission of these sources under the hypothesis that the emission is solely of hadronic origin. this prediction relies entirely on observation and is independent of the source class, the distance or the ambient target material. we use these predictions to create an empirical model for the neutrino emission of the milky way. this model can be used to search for neutrino emission from individual gamma - ray sources as well as testing for neutrino emission from potential source populations in the milky way.
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arxiv:2111.14815
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we use a controlled laboratory experiment to study the causal impact of income decreases within a time period on redistribution decisions at the end of that period, in an environment where we keep fixed the sum of incomes over the period. first, we investigate the effect of a negative income trend ( intra - personal decrease ), which means a decreasing income compared to one ' s recent past. second, we investigate the effect ofa negative income trend relative to the income trend of another person ( inter - personal decrease ). if intra - personal or inter - personal decreases create dissatisfaction for an individual, that person may become more selfish to obtain compensation. we formal - ize both effects in a multi - period model augmenting a standard model of inequality aversion. overall, conditional on exhibiting sufficiently - strong social preferences, we find that individuals indeed behave more selfishly when they experience decreasing incomes. while many studies examine the effect of income inequality on redistribution decisions, we delve into the history behind one ' s income to isolate the effect of income changes.
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arxiv:2107.02888
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we study the homotopy type of spaces of commuting elements in connected nilpotent lie groups, via almost commuting elements in their lie algebras. we give a necessary and sufficient condition on the fundamental group of such a lie group $ g $ to ensure $ \ mathrm { hom } ( \ mathbb { z } ^ k, g ) $ is path - connected. in particular for the reduced upper unitriangular groups and the reduced generalized heisenberg groups, $ \ mathrm { hom } ( \ mathbb { z } ^ k, g ) $ is not path - connected, and we compute the homotopy type of its path - connected components in terms of stiefel manifolds and the maximal torus of $ g $.
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arxiv:2405.09652
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we introduce a new set of consistent measures of risks, in terms of the semi - invariants of pdf ' s, such that the centered moments and the cumulants of the portfolio distribution of returns that put more emphasis on the tail the distributions. we derive generalized efficient frontiers, based on these novel measures of risks and present the generalized capm, both in the cases of homogeneous and heterogeneous markets. then, using a family of modified weibull distributions, encompassing both sub - exponentials and super - exponentials, to parameterize the marginal distributions of asset returns and their natural multivariate generalizations, we offer exact formulas for the moments and cumulants of the distribution of returns of a portfolio made of an arbitrary composition of these assets. using combinatorial and hypergeometric functions, we are in particular able to extend previous results to the case where the exponents of the weibull distributions are different from asset to asset and in the presence of dependence between assets. in this parameterization, we treat in details the problem of risk minimization using the cumulants as measures of risks for a portfolio made of two assets and compare the theoretical predictions with direct empirical data. our extended formulas enable us to determine analytically the conditions under which it is possible to ` ` have your cake and eat it too ' ', i. e., to construct a portfolio with both larger return and smaller ` ` large risks ' '.
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arxiv:cond-mat/0207475
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deep learning has improved performance on many natural language processing ( nlp ) tasks individually. however, general nlp models cannot emerge within a paradigm that focuses on the particularities of a single metric, dataset, and task. we introduce the natural language decathlon ( decanlp ), a challenge that spans ten tasks : question answering, machine translation, summarization, natural language inference, sentiment analysis, semantic role labeling, zero - shot relation extraction, goal - oriented dialogue, semantic parsing, and commonsense pronoun resolution. we cast all tasks as question answering over a context. furthermore, we present a new multitask question answering network ( mqan ) jointly learns all tasks in decanlp without any task - specific modules or parameters in the multitask setting. mqan shows improvements in transfer learning for machine translation and named entity recognition, domain adaptation for sentiment analysis and natural language inference, and zero - shot capabilities for text classification. we demonstrate that the mqan ' s multi - pointer - generator decoder is key to this success and performance further improves with an anti - curriculum training strategy. though designed for decanlp, mqan also achieves state of the art results on the wikisql semantic parsing task in the single - task setting. we also release code for procuring and processing data, training and evaluating models, and reproducing all experiments for decanlp.
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arxiv:1806.08730
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vertical federated learning ( vfl ) is an effective paradigm of training the emerging cross - organizational ( e. g., different corporations, companies and organizations ) collaborative learning with privacy preserving. stochastic gradient descent ( sgd ) methods are the popular choices for training vfl models because of the low per - iteration computation. however, existing sgd - based vfl algorithms are communication - expensive due to a large number of communication rounds. meanwhile, most existing vfl algorithms use synchronous computation which seriously hamper the computation resource utilization in real - world applications. to address the challenges of communication and computation resource utilization, we propose an asynchronous stochastic quasi - newton ( asysqn ) framework for vfl, under which three algorithms, i. e. asysqn - sgd, - svrg and - saga, are proposed. the proposed asysqn - type algorithms making descent steps scaled by approximate ( without calculating the inverse hessian matrix explicitly ) hessian information convergence much faster than sgd - based methods in practice and thus can dramatically reduce the number of communication rounds. moreover, the adopted asynchronous computation can make better use of the computation resource. we theoretically prove the convergence rates of our proposed algorithms for strongly convex problems. extensive numerical experiments on real - word datasets demonstrate the lower communication costs and better computation resource utilization of our algorithms compared with state - of - the - art vfl algorithms.
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arxiv:2109.12519
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in this paper we continue the investigation, within the context of the dijkgraaf - vafa programme, of seiberg duality in matrix models as initiated in hep - th / 0211202, by allowing degenerate mass deformations. in this case, there are some massless fields which remain and the theory has a moduli space. with this illustrative example, we propose a general methodology for performing the relevant matrix model integrations and addressing the corresponding field theories which have non - trivial ir behaviour, and which may or may not have tree - level superpotentials.
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arxiv:hep-th/0211234
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there are many observational evidences for the existence of massive compact condensations in the range $ 10 ^ 6 - 10 ^ { 10 } m _ \ odot $ at the core of various galaxies. at present such condensations are commonly interpreted as black holes ( bhs ). however, we point out that while such black hole candidates ( bhcs ) must be similar to bhs in many respects they, actually, can not be bhs because existence of black holes would violate the basic tenet of the general theory of relativity ( gtr ) that the worldline of a material particle must be timelike at any regular region of spacetime. on the other hand general relativistic collapse of very massive bodies should lead to eternally collapsing configurations ( ecos ) or ultra compact objects ( ucos ). while ecos / ucos may practically be as compact as corresponding bhs, they will have a physical surface. also while bhs do not have any intrinsic magnetic field ecos may have strong intrinsic magnetic field. we point out that despite many claims actually there is no real evidence for the ` ` event horizon ' ' ( eh ) of supposed bhs and on the other hand, there are tentative evidence for the existence of strong magnetic field in several bhcs ( or ecos ). the presence of such intrinsic magnetic field may render the task of explaining high energy radiation phenomenon in many active galactic nuclei easier.
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arxiv:astro-ph/0205261
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in this paper, we consider the problem of reconstructing piecewise smooth functions to high accuracy from nonuniform samples of their fourier transform. we use the framework of nonuniform generalized sampling ( nugs ) to do this, and to ensure high accuracy we employ reconstruction spaces consisting of splines or ( piecewise ) polynomials. we analyze the relation between the dimension of the reconstruction space and the bandwidth of the nonuniform samples, and show that it is linear for splines and piecewise polynomials of fixed degree, and quadratic for piecewise polynomials of varying degree.
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arxiv:1410.0088
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correlated electrons in transition metal oxides ( tmos ) exhibit a variety of emergent phases. when tmos are confined to a single - atomic - layer thickness, experiments so far have shown that they usually lose diverse properties and become insulators. in an attempt to extend the range of electronic phases of the single - atomic - layer oxide, we search for a metallic phase in a monolayer - thick epitaxial srruo $ _ 3 $ film. combining atomic - scale epitaxy and angle - resolved photoemission measurements, we show that the monolayer srruo $ _ 3 $ is a strongly correlated metal. systematic investigation reveals that the interplay between dimensionality and electronic correlation makes the monolayer srruo $ _ 3 $ an incoherent metal with orbital - selective correlation. furthermore, the unique electronic phase of the monolayer srruo $ _ 3 $ is found to be highly tunable, as charge modulation demonstrates an incoherent - to - coherent crossover of the two - dimensional metal. our work emphasizes the potentially rich phases of single - atomic - layer oxides and provides a guide to the manipulation of their two - dimensional correlated electron systems.
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arxiv:2109.11090
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in this work is presented a weakened version of the left exact preradicals : the prehereditary preradicals. also is presented a weakened version of the idempotent preradicals : the essentially idempotent preradicals. these new classes of prerradicals are studied under the lattice theory. each class serves to generalize the theorems of the injectivity respect to a torsion theory.
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arxiv:1511.01222
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