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in view of the realistic possibility for operating high - energy polarized proton beams in future collider machines, it is highly desirable to propose for such beams, an absolute calibration allowing to measure accurately their degree of polarization. we consider more specifically one practical method based on pp elastic scattering near the forward direction and we discuss its limitations. | arxiv:hep-ph/9611234 |
we used alma to perform a line survey of the high - mass star forming region sgr b2 ( n ), called remoca. we modeled under the assumption of lte the spectra obtained toward the sources embedded in the secondary hot core sgr b2 ( n2 ). we compared the chemical composition of these sources to that of sources from the literature and to predictions of the chemical kinetics model magickal. we detected up to 58 molecules toward sgr b2 ( n2 ) ' s hot cores, including up to 24 coms, as well as many less abundant isotopologs. the compositions of some pairs of sources are well correlated, but differences also exist in particular for hnco and nh2cho. the abundances of series of homologous molecules drop by about one order of magnitude at each further step in complexity. the nondetection of radicals yields stringent constraints on the models. the comparison to the chemical models confirms previous evidence of a high cosmic - ray ionization rate in sgr b2 ( n ). the comparison to sources from the literature gives new insight into chemical differentiation. the composition of most hot cores of sgr b2 ( n2 ) is tightly correlated to that of the hot core g31. 41 + 0. 31 and the hot corino iras 16293 - 2422b after normalizing the abundances by classes of molecules ( o -, n -, o + n -, and s - bearing ). there is no overall correlation between sgr b2 ( n2 ) and the shocked region g + 0. 693 - 0. 027 also located in sgr b2, and even less with the cold starless core tmc - 1. the class of n - bearing species reveals the largest variance among the four classes of molecules. the s - bearing class shows in contrast the smallest variance. these results imply that the class of n - bearing molecules reacts more sensitively to shocks, low - temperature gas phase chemistry after non - thermal desorption, or density. the abundance shifts observed between the n - and o - bearing molecules may indicate how violently and completely the ice mantles are desorbed. [ abridged ] | arxiv:2505.03262 |
we are using the finite - gap approach for the construction of the schr \ " { o } dinger operator discretization on a quad graph. the latter is represented by a two - dimensional integer sublattice in a $ d $ - dimensional space. the green ' s function of the operator can be posed explicitly as an integral of the differential built by the spectral data, calculated on contours of the special form. we also know the the asymptotics of the achieved function. | arxiv:1402.2629 |
jupiter - family comet 15p / finlay has been reportedly quiet in activity for over a century but has harbored two outbursts during its 2014 / 2015 perihelion passage. here we present an analysis of these two outbursts using a set of cometary observations. the outbursts took place between 2014 dec. 15. 4 - - 16. 0 ut and 2015 jan. 15. 5 - - 16. 0 ut as constrained by ground - based and spacecraft observations. we find a characteristic ejection speed of $ v _ 0 = 300 $ to $ 650 \ mathrm { m \ cdot s ^ { - 1 } } $ for the ejecta of the first outburst and $ v _ 0 = 550 $ to $ 750 \ mathrm { m \ cdot s ^ { - 1 } } $ for that of the second outburst using a monte carlo dust model. the mass of the ejecta is calculated to be $ m _ \ mathrm { d } = 2 $ to $ 3 \ times10 ^ 5 \ mathrm { kg } $ for the first outburst and $ m _ \ mathrm { d } = 4 $ to $ 5 \ times10 ^ 5 \ mathrm { kg } $ for the second outburst, corresponds to less than $ 10 ^ { - 7 } $ of the nucleus mass. the specific energy of the two outbursts is found to be $ 0. 3 $ to $ 2 \ times10 ^ 5 \ mathrm { j \ cdot kg ^ { - 1 } } $. we also revisit the long - standing puzzle of the non - detection of the hypothetical finlayid meteor shower by performing a cued search using the 13 - year data from the canadian meteor orbit radar, which does not reveal any positives. the earth will pass the 2014 / 2015 outburst ejecta around 2021 oct. 6 at 22 h ut to oct. 7 at 1 h ut, with a chance for some significant meteor activity in the radio range, which may provide further clues to the finlayid puzzle. a southerly radiant in the constellation of ara will favor the observers in the southern tip of africa. | arxiv:1510.06645 |
we introduce a measure of complexity in terms of the average number of bits per time unit necessary to specify the sequence generated by the system. in random dynamical system, this indicator coincides with the rate k of divergence of nearby trajectories evolving under two different noise realizations. the meaning of k is discussed in the context of the information theory, and it is shown that it can be determined from real experimental data. in presence of strong dynamical intermittency, the value of k is very different from the standard lyapunov exponent computed considering two nearby trajectories evolving under the same randomness. however, the former is much more relevant than the latter from a physical point of view as illustrated by some numerical computations for noisy maps and sandpile models. | arxiv:cond-mat/9505054 |
we present the polarization images in the $ j $, $ h $, & $ ks $ bands of the orion molecular cloud 1 south region. the polarization images clearly show at least six infrared reflection nebulae ( irne ) which are barely seen or invisible in the intensity images. our polarization vector images also identify the illuminating sources of the nebulae : irn 1 & 2, irn 3, 4, & 5, and irn 6 are illuminated by three ir sources, source 144 - 351, source 145 - 356, and source 136 - 355, respectively. moreover, our polarization images suggest the candidate driving sources of the optical herbig - haro objects for the first time ; hh529, a pair of hh202 and hh528 or hh 203 / 204, hh 530 and hh269 are originated from source 144 - 351, source 145 - 356, and source 136 - 355, respectively. | arxiv:astro-ph/0612519 |
we offer a few comments derived from a careful reading of michael strevens ' book { \ it the knowledge machine } ( tkm ), with an emphasis on extensions for future work. we believe this book goes well beyond traditional accounts of scientific change, and offers thus many insights into new research. | arxiv:2107.11681 |
this report embarks on a mission to revolutionize clinical trial protocol development through the integration of advanced ai technologies. with a focus on leveraging the capabilities of generative ai, specifically gpt - 4, this initiative aimed to streamline and enhance the efficiency and accuracy of clinical trial protocols. the methodology encompassed a detailed analysis and preparation of comprehensive drug and study level metadata, followed by the deployment of gpt - 4 for automated protocol section generation. results demonstrated a significant improvement in protocol authoring, highlighted by increases in efficiency, accuracy, and the customization of protocols to specific trial requirements. challenges encountered during model selection and prompt engineering were systematically addressed, leading to refined methodologies that capitalized on the advanced text generation capabilities of gpt - 4. this project not only showcases the practical applications and benefits of generative ai in clinical trial design but also sets a foundation for future innovations in the field. | arxiv:2404.05044 |
we consider the supergravity dual of the n = 1 * theory at finite temperature by applying the polchinski - strassler construction to the black d3 brane solution of type iib supergravity. at finite temperature the 5 - brane probe action is minimized when the probe falls to the horizon, although metastable minima with r > > r _ h persist for a range of temperatures. thermal effects on the 3 - form source for the hypermultiplet mass m and its order m ^ 2 back reaction on the other fields of the iib theory are computed. we find unique solutions which are regular at the horizon and have the correct behavior on the boundary. for fixed temperature t, the horizon shrinks for increasing m ^ 2 suggesting that there is a critical temperature separating the system into high and low temperature phases. in the high temperature phase 5 - branes are unnecessary since there are no naked singularities. using the order m ^ 2 correction to the horizon area we calculate the correction to the entropy to be \ delta s = - 0. 1714n ^ 2m ^ 2t, which is less than the free field result. | arxiv:hep-th/0007250 |
this paper aims to bring a new lightweight yet powerful solution for the task of emotion recognition and sentiment analysis. our motivation is to propose two architectures based on transformers and modulation that combine the linguistic and acoustic inputs from a wide range of datasets to challenge, and sometimes surpass, the state - of - the - art in the field. to demonstrate the efficiency of our models, we carefully evaluate their performances on the iemocap, mosi, mosei and meld dataset. the experiments can be directly replicated and the code is fully open for future researches. | arxiv:2010.02057 |
we generalize the partial derivative automaton to regular expressions with shuffle and study its size in the worst and in the average case. the number of states of the partial derivative automata is in the worst case at most 2 ^ m, where m is the number of letters in the expression, while asymptotically and on average it is no more than ( 4 / 3 ) ^ m. | arxiv:1503.00279 |
self - supervised representation learning ( ssrl ) has demonstrated superior performance than supervised models for tasks including phoneme recognition. training ssrl models poses a challenge for low - resource languages where sufficient pre - training data may not be available. a common approach is cross - lingual pre - training. instead, we propose to use audio augmentation techniques, namely : pitch variation, noise addition, accented target language and other language speech to pre - train ssrl models in a low resource condition and evaluate phoneme recognition. our comparisons found that a combined synthetic augmentations ( noise / pitch ) strategy outperformed accent and language knowledge transfer. furthermore, we examined the scaling factor of augmented data to achieve equivalent performance to model pre - trained with target domain speech. our findings suggest that for resource - constrained languages, combined augmentations can be a viable option than other augmentations. | arxiv:2309.12763 |
microservice architecture ( msa ) is gaining rapid popularity for developing large - scale iot applications for deployment within distributed and resource - constrained fog computing environments. as a cloud - native application architecture, the true power of microservices comes from their loosely coupled, independently deployable and scalable nature, enabling distributed placement and dynamic composition across federated fog and cloud clusters. thus, it is necessary to develop novel microservice placement algorithms that utilise these microservice characteristics to improve the performance of the applications. however, existing fog computing frameworks lack support for integrating such placement policies due to their shortcomings in multiple areas, including msa application placement and deployment across multi - fog multi - cloud environments, dynamic microservice composition across multiple distributed clusters, scalability of the framework, support for deploying heterogeneous microservice applications, etc. to this end, we design and implement microfog, a fog computing framework providing a scalable, easy - to - configure control engine that executes placement algorithms and deploys applications across federated fog environments. furthermore, microfog provides a sufficient abstraction over container orchestration and dynamic microservice composition. the framework is evaluated using multiple use cases. the results demonstrate that microfog is a scalable, extensible and easy - to - configure framework that can integrate and evaluate novel placement policies for deploying microservice - based applications within multi - fog multi - cloud environments. we integrate multiple microservice placement policies to demonstrate microfog ' s ability to support horizontally scaled placement, thus reducing the application service response time up to 54 %. | arxiv:2302.06971 |
the band - limited coronagraph is a nearly ideal concept that theoretically enables perfect cancellation of all the light of an on - axis source. over the past years, several prototypes have been developed and tested in the laboratory, and more emphasis is now on developing optimal technologies that can efficiently deliver the expected high - contrast levels of such a concept. following the development of an early near - ir demonstrator, we present and discuss the results of a second - generation prototype using halftone - dot technology. we report improvement in the accuracy of the control of the local transmission of the manufactured prototype, which was measured to be less than 1 %. this advanced h - band band - limited device demonstrated excellent contrast levels in the laboratory, down to 10 - 6 at farther angular separations than 3 lambda / d over 24 % spectral bandwidth. these performances outperform the ones of our former prototype by more than an order of magnitude and confirm the maturity of the manufacturing process. current and next generation high - contrast instruments can directly benefit from such capabilities. in this context, we experimentally examine the ability of the band - limited coronagraph to withstand various complex telescope apertures. | arxiv:1111.6956 |
for any non - uniform lattice $ \ gamma $ in $ sl ( 2, r ) $, we describe the limit distribution of orthogonal translates of a divergent geodesic in $ \ gamma \ backslash sl ( 2, r ) $. as an application, for a quadratic form $ q $ of signature $ ( 2, 1 ) $, a lattice $ \ gamma $ in its isometry group, and $ v _ 0 \ in r ^ 3 $ with $ q ( v _ 0 ) > 0 $, we compute the asymptotic ( with a logarithmic error term ) of the number of points in a discrete orbit $ v _ 0 \ gamma $ of norm at most $ t $, when the stabilizer of $ v _ 0 $ in $ \ gamma $ is finite. our result in particular implies that for any non - zero integer $ d $, the smoothed count for number of integral binary quadratic forms with discriminant $ d ^ 2 $ and with coefficients bounded by $ t $ is asymptotic to $ c \ cdot t \ log t + o ( t ) $. | arxiv:1104.4988 |
a new determination of the sound horizon scale in angular coordinates is presented. it makes use of ~ 0. 6 x 10 ^ 6 luminous red galaxies, selected from the sloan digital sky survey imaging data, with photometric redshifts. the analysis covers a redshift interval that goes from z = 0. 5 to z = 0. 6. we find evidence of the baryon acoustic oscillations ( bao ) signal at the ~ 2. 3 sigma confidence level, with a value of theta _ { bao } ( z = 0. 55 ) = ( 3. 90 \ pm 0. 38 ) degrees, including systematic errors. to our understanding, this is the first direct measurement of the angular bao scale in the galaxy distribution, and it is in agreement with previous bao measurements. we also show how radial determinations of the bao scale can break the degeneracy in the measurement of cosmological parameters when they are combined with bao angular measurements. the result is also in good agreement with the wmap7 best - fit cosmology. we obtain a value of w _ 0 = - 1. 03 \ pm 0. 16 for the equation of state parameter of the dark energy, omega _ m = 0. 26 \ pm 0. 04 for the matter density, when the other parameters are fixed. we have also tested the sensitivity of current bao measurements to a time varying dark energy equation of state, finding w _ a = 0. 06 \ pm 0. 22 if we fix all the other parameters to the wmap7 best - fit cosmology. | arxiv:1104.5426 |
we present new expressions for the $ k $ - generalized fibonacci numbers, say $ f _ k ( n ) $. they satisfy the recurrence $ f _ k ( n ) = f _ k ( n - 1 ) + \ dots + f _ k ( n - k ) $. explicit expressions for the roots of the auxiliary ( or characteristic ) polynomial are presented, using fuss - catalan numbers. properties of the roots are enumerated. we quantify the accuracy of asymptotic approximations for $ f _ k ( n ) $ for $ n \ gg1 $. our results subsume and extend some results published by previous authors. we also comment on the use of multinomial sums for the $ k $ - generalized fibonacci numbers and related sequences. we also employ the generating function to express $ f _ k ( n ) $ as a concise ( non - nested ) sum of binomial coefficients for arbitrary $ k $. finally, we present a basis ( or ` fundamental solutions ' ) to solve the above recurrence for arbitrary initial conditions. | arxiv:2410.07922 |
pulsar binaries, in particular redback systems, provide good sources to study the pulsar wind flow and its interaction with the companion stars. { \ it fermi } - lat have proposed probable pulsar binary candidates in its catalogs. to identify pulsar binary sources from the catalog, orbital modulation search of binary candidates is an effective way. tess observes in survey mode for a large part of the sky and thus provide an excellent data set to periodicity search of pulsar binary candidates by observing the flux variation, thought to mainly come from the stellar companion. using tess data we look for flux modulation of five pulsar binaries ( or candidates ) with reported orbital periods, including psr j1023 + 0038, 3fgl j0523. 3 - 2528, 3fgl j0212. 1 + 5320, 3fgl j0744. 1 - 2523 and psr j1417 - 4402, demonstrating that tess photometric data are very useful in identifying periodicities of redback - like systems. this method can be effective in searches for new pulsar binaries or similar binary systems in the future. | arxiv:2005.06841 |
this paper presents an explainable fault detection and diagnosis system ( xfdds ) for incipient faults in pv panels. the xfdds is a hybrid approach that combines the model - based and data - driven framework. model - based fdd for pv panels lacks high fidelity models at low irradiance conditions for detecting incipient faults. to overcome this, a novel irradiance based three diode model ( ib3dm ) is proposed. it is a nine parameter model that provides higher accuracy even at low irradiance conditions, an important aspect for detecting incipient faults from noise. to exploit pv data, extreme gradient boosting ( xgboost ) is used due to its ability to detecting incipient faults. lack of explainability, feature variability for sample instances, and false alarms are challenges with data - driven fdd methods. these shortcomings are overcome by hybridization of xgboost and ib3dm, and using explainable artificial intelligence ( xai ) techniques. to combine the xgboost and ib3dm, a fault - signature metric is proposed that helps reducing false alarms and also trigger an explanation on detecting incipient faults. to provide explainability, an explainable artificial intelligence ( xai ) application is developed. it uses the local interpretable model - agnostic explanations ( lime ) framework and provides explanations on classifier outputs for data instances. these explanations help field engineers / technicians for performing troubleshooting and maintenance operations. the proposed xfdds is illustrated using experiments on different pv technologies and our results demonstrate the perceived benefits. | arxiv:2011.09843 |
the possibility that gamma - ray bursts ( grbs ) were not isotropic emissions was devised theoretically as a way to ameliorate the huge energetic budget implied by the standard fireball model for these powerful phenomena. however, the mechanism by which after the quasy - isotropic release of a few $ 10 ^ { 50 } $ erg yields a collimated ejection of plasma could not be satisfactory explained analytically. the reason being that the collimation of an outflow by its progenitor system depends on a very complex and non - linear dynamics. that has made necessary the use of numerical simulations in order to shed some light on the viability of some likely progenitors of grbs. in this contribution i will review the most relevant features shown by these numerical simulations and how they have been used to validate the collapsar model ( for long grbs ) and the model involving the merger of compact binaries ( for short grbs ). | arxiv:astro-ph/0701187 |
these proceedings show the preliminary results of the dijet longitudinal double spin asymmetry $ a _ { ll } $ in polarized proton - proton collisions at $ \ sqrt { s } = 200 $ gev for the pseudorapidity range $ | \ eta | \ le 0. 8 $. the integrated luminosity of 10. 6 pb $ ^ { - 1 } $ used in this analysis was collected during rhic run - 9. this result is presented as a function of the dijet invariant mass in multiple pseudorapidity acceptances. the division into different pseudorapidity regions allows the kinematics of the hard interaction to be constrained and information about the shape of $ \ delta g ( x ) $ to be extracted for the first time. comparisons are made with expectations from various different theoretical scenarios of polarized parton distributions of the proton. | arxiv:1107.0917 |
a quantum computing scheme that uses a single photon and multiple - slit gratings is suggested for the hamiltonian path problem on a simple graph g of n vertices. the photon is input to an n - slit grating followed by an n x n matrix of ` processing units '. a unit consists of a delay line followed by a grating with k slits ( 0 < k < n ) whose outputs are directed to k units in the next row in a manner determined by the adjacency matrix of g. there is a one - to - one mapping between paths of length n - 1 in the graph and physical paths through the matrix. the photon ' s path is a superposition of all these physical paths. the time taken by the photon along a physical path corresponding to a hamiltonian path in g is a fixed value equal to the sum of n distinct delays, and is different from the time along any other path. the graph is hamiltonian if any one of n detectors placed in the output of the n units in row n detects the photon at this fixed time. | arxiv:quant-ph/0101142 |
we consider the decoherence of phase space histories in a class of quantum brownian motion models, consisting of a particle moving in a potential $ v ( x ) $ in interaction with a heat bath at temperature $ t $ and dissipation gamma, in the markovian regime. the evolution of the density operator for this open system is thus described by a non - unitary master equation. the phase space histories of the system are described by a class of quasiprojectors. generalizing earlier results of hagedorn and omn \ ` es, we show that a phase space projector onto a phase space cell $ \ gamma $ is approximately evolved under the master equation into another phase space projector onto the classical dissipative evolution of $ \ gamma $, and with a certain amount of degradation due to the noise produced by the environment. we thus show that histories of phase space samplings approximately decohere, and that the probabilities for these histories are peaked about classical dissipative evolution, with a width of peaking depending on the size of the noise. | arxiv:quant-ph/9506031 |
the goal of this paper is to give a numerical criterion for an open question in $ p $ - adic fourier theory. let $ f $ be a finite extension of $ \ mathbf { q } _ p $. schneider and teitelbaum defined and studied the character variety $ \ mathfrak { x } $, which is a rigid analytic curve over $ f $ that parameterizes the set of locally $ f $ - analytic characters $ \ lambda : ( o _ f, + ) \ to ( \ mathbf { c } _ p ^ \ times, \ times ) $. determining the structure of the ring $ \ lambda _ f ( \ mathfrak { x } ) $ of bounded - by - one functions on $ \ mathfrak { x } $ defined over $ f $ seems like a difficult question. using the katz isomorphism, we prove that if $ f = \ mathbf { q } _ { p ^ 2 } $, then $ \ lambda _ f ( \ mathfrak { x } ) = o _ f [ \! [ o _ f ] \! ] $ if and only if the $ o _ f $ - module of integer - valued polynomials on $ o _ f $ is generated by a certain explicit set. some computations in sagemath indicate that this seems to be the case. | arxiv:2502.18053 |
performing molecular dynamics simulations, we find that the structural relaxation dynamics of viscous silica, the prototype of a strong glass former, are spatially heterogeneous and cannot be understood as a statistical bond breaking process. further, we show that high particle mobility predominantly propagates continuously through the melt, supporting the concept of dynamic facilitation emphasized in recent theoretical work. | arxiv:cond-mat/0402427 |
not meet the requirements of the program of constructivism because it is a theory in classical logic including the law of excluded middle. despite its seeming weakness ( of not proving any non - computable sets exist ), rca0 is sufficient to prove a number of classical theorems which, therefore, require only minimal logical strength. these theorems are, in a sense, below the reach of the reverse mathematics enterprise because they are already provable in the base system. the classical theorems provable in rca0 include : basic properties of the natural numbers, integers, and rational numbers ( for example, that the latter form an ordered field ). basic properties of the real numbers ( the real numbers are an archimedean ordered field ; any nested sequence of closed intervals whose lengths tend to zero has a single point in its intersection ; the real numbers are not countable ). section ii. 4 the baire category theorem for a complete separable metric space ( the separability condition is necessary to even state the theorem in the language of second - order arithmetic ). theorem ii. 5. 8 the intermediate value theorem on continuous real functions. theorem ii. 6. 6 the banach – steinhaus theorem for a sequence of continuous linear operators on separable banach spaces. theorem ii. 10. 8 a weak version of godel ' s completeness theorem ( for a set of sentences, in a countable language, that is already closed under consequence ). the existence of an algebraic closure for a countable field ( but not its uniqueness ). ii. 9. 4 - - ii. 9. 8 the existence and uniqueness of the real closure of a countable ordered field. ii. 9. 5, ii. 9. 7 the first - order part of rca0 ( the theorems of the system that do not involve any set variables ) is the set of theorems of first - order peano arithmetic with induction limited to σ01 formulas. it is provably consistent, as is rca0, in full first - order peano arithmetic. = = = weak konig ' s lemma wkl0 = = = the subsystem wkl0 consists of rca0 plus a weak form of konig ' s lemma, namely the statement that every infinite subtree of the full binary tree ( the tree of all finite sequences of 0 ' s and 1 ' s ) has an infinite path. this proposition, which is known as weak konig ' s lemma, is easy | https://en.wikipedia.org/wiki/Reverse_mathematics |
arabic, with its rich diversity of dialects, remains significantly underrepresented in large language models, particularly in dialectal variations. we address this gap by introducing seven synthetic datasets in dialects alongside modern standard arabic ( msa ), created using machine translation ( mt ) combined with human post - editing. we present aradice, a benchmark for arabic dialect and cultural evaluation. we evaluate llms on dialect comprehension and generation, focusing specifically on low - resource arabic dialects. additionally, we introduce the first - ever fine - grained benchmark designed to evaluate cultural awareness across the gulf, egypt, and levant regions, providing a novel dimension to llm evaluation. our findings demonstrate that while arabic - specific models like jais and acegpt outperform multilingual models on dialectal tasks, significant challenges persist in dialect identification, generation, and translation. this work contributes $ \ approx $ 45k post - edited samples, a cultural benchmark, and highlights the importance of tailored training to improve llm performance in capturing the nuances of diverse arabic dialects and cultural contexts. we have released the dialectal translation models and benchmarks developed in this study ( https : / / huggingface. co / datasets / qcri / aradice ). | arxiv:2409.11404 |
advances in microgrids powered by distributed energy resources ( ders ) make them an attractive response capability for improving the resilience of electricity distribution networks ( dns ). this paper presents an approach to evaluate the value of implementing a timely response using microgrid operations and der dispatch in the aftermath of a disruption event, involving strategic compromise of multiple dn components. firstly, we extend the resiliency assessment framework in [ 1 ] and develop a sequential ( bilevel ) model of attacker - operator interactions on a radial dn with one or more microgrids. particularly, the operator response includes microgrid operations under various islanding configurations ( regimes ), and single - or multi - master operation of ders in providing grid - forming services as well as frequency and voltage regulation. secondly, we introduce a restoration problem in which the operator gradually reconnects the disrupted components over multiple periods to restore the nominal performance of the dn. the first problem, formulated as a bilevel mixed - integer problem, is solved using a benders decomposition method. the second problem, formulated as a multi - period mixed - integer problem, can be solved using a greedy algorithm. our results illustrate the benefit of using microgrids in reducing the operator ' s losses, both immediately after the disruption event and during the restoration process. | arxiv:1812.01745 |
we derive the exact density profile of a harmonically trapped bose - einstein condensate ( bec ) which has dipole - dipole interactions as well as the usual s - wave contact interaction, in the thomas - fermi limit. remarkably, despite the non - local anisotropic nature of the dipolar interaction, the density turns out to be an inverted parabola, just as in the pure s - wave case, but with a modified aspect ratio. the ` ` scaling ' ' solution approach of kagan, surkov, and shlyapnikov [ phys. rev. a 54, 1753 ( 1996 ) ] and castin and dum [ phys. rev. lett. 77 }, 5315 ( 1996 ) ] for a bec in a time - dependent trap can therefore be applied to a dipolar bec, and we use it to obtain the exact monopole and quadrupole shape oscillation frequencies. | arxiv:cond-mat/0308096 |
recently, workforce shortage has become a popular issue in information technology ( it ). one solution to increasing the workforce supply is to increase the number of female it professionals. this is because there is gender imbalance in information technology area. to accomplish this, it is important to suppress the influence of biases, such as the belief that men are more suited for careers in science and technology than women, and to increase the choice of careers available to female professionals. to help suppress the influence of gender bias, we analyzed the relationship between gender and code reading speed in the field of software development. certain source codes require developers to use substantial memory to properly understand them, such as those with many variables that frequently change values. several studies have indicated that the performance of memory differs in males and females. to test the veracity of this claim, we analyzed the influence of gender on code - reading speed through an experiment. pursuant to this, we prepared four programs that required varied amounts of memory to properly understand them. then, we measured the time required by each of the 17 male and 16 female subjects ( 33 subjects in total ) to comprehend the different programs. the results suggest that there is no explicit difference between male and female subjects in this regard, even in the case of programs that require high memory capacities for proper understanding. | arxiv:2209.03516 |
from conformal field theory on the riemann sphere, we implement its boundary version in a simply - connected domain using the schottky double construction. we consider the statistical fields generated by background charge modification of the gaussian free field with dirichlet boundary condition under the ope multiplications. we prove that the correlation functions of such fields with symmetric background charges form a collection of martingale - observables for ( forward ) chordal / radial sle with force points and spins. we also present the connection between conformal field theory with neumann boundary condition and the theory of backward sle. | arxiv:2111.10057 |
the science in science fiction is a book by david langford, peter nicholls and brian stableford published in 1982. the book is divided into twelve chapters. the first eleven chapters each examine science fiction works about a particular topic, such as space flight, aliens or time travel, and discuss how accurate the works are to real science ; the final chapter of the book covers notable instances " where science fiction gets it wrong ". = = reception = = dave pringle, the former editor of foundation and interzone, reviewed the book for imagine magazine in april 1983, describing it as " an excellent and timely work of non - fiction, " and stated he hopes " every would - be sf writer in the land reads this book and comes to the realisation that raw imagination and an ability with words are not enough ; a modicum of knowledge has always been necessary to the creation of worthwhile science - fiction. " science fiction author gene deweese reviewed the book for science fiction review in may 1983, recommending the book to any science fiction reader who wants to know if the events depicted could actually happen. his review was mostly positive, particularly complimenting the book ' s " clear and interesting prose " and its illustrations, although he criticized david langford for coming across as condescending and " fail [ ing ] to distinguish between authors who made silly mistakes because of ignorance and those who purposely violated current scientific theories. " the book was also reviewed by gregory benford in issue # 267 of locus in april 1983 review by patrick parrinder ( 1983 ) in science fiction & fantasy book review, # 11, january - february 1983 review by neil barron ( 1983 ) in science fiction & fantasy book review, # 11, january - february 1983 review by ken methold ( 1983 ) in omega science digest, september - october 1983 review by duncan lunan ( 1983 ) in the bulletin of the science fiction writers of america, fall 1983 review [ german ] by uwe anton ( 1984 ) in science fiction times, januar 1984 review by andrew c. murdoch ( 1993 ) in zx, july - august 1993 = = references = = | https://en.wikipedia.org/wiki/The_Science_in_Science_Fiction |
we investigate the behavior of quasiparticles in a hybrid electron turnstile with the aim of improving its performance as a metrological current source. the device is used to directly probe the density of quasiparticles and monitor their relaxation into normal metal traps. we compare different trap geometries and reach quasiparticle densities below 3um ^ - 3 for pumping frequencies of 20 mhz. our data show that quasiparticles are excited both by the device operation itself and by the electromagnetic environment of the sample. our observations can be modelled on a quantitative level with a sequential tunneling model and a simple diffusion equation. | arxiv:1204.1028 |
today ' s software is bloated with both code and features that are not used by most users. this bloat is prevalent across the entire software stack, from operating systems and applications to containers. containers are lightweight virtualization technologies used to package code and dependencies, providing portable, reproducible and isolated environments. for their ease of use, data scientists often utilize machine learning containers to simplify their workflow. however, this convenience comes at a cost : containers are often bloated with unnecessary code and dependencies, resulting in very large sizes. in this paper, we analyze and quantify bloat in machine learning containers. we develop mmlb, a framework for analyzing bloat in software systems, focusing on machine learning containers. mmlb measures the amount of bloat at both the container and package levels, quantifying the sources of bloat. in addition, mmlb integrates with vulnerability analysis tools and performs package dependency analysis to evaluate the impact of bloat on container vulnerabilities. through experimentation with 15 machine learning containers from tensorflow, pytorch, and nvidia, we show that bloat accounts for up to 80 % of machine learning container sizes, increasing container provisioning times by up to 370 % and exacerbating vulnerabilities by up to 99 %. | arxiv:2212.09437 |
we explore recurrence properties arising from dynamical approach to combinatorial problems like the van der waerden theorem. we describe relations between these properties, study their consequences for dynamics, and demonstrate connections to combinatorial problems. in particular, we present a measure - theoretical analog of a result of glasner on multi - transitivity in topological weakly mixing minimal maps. we also obtain a dynamical proof of the existence of a c - set with zero banach density. | arxiv:1501.01491 |
the large sky area multi - object fiber spectroscopic telescope ( lamost ) started median - resolution spectroscopic ( mrs, r $ \ sim $ 7500 ) survey since october 2018. the main scientific goals of mrs, including binary stars, pulsators, and other variable stars are launched with a time - domain spectroscopic survey. however, the systematic errors, including the bias induced from wavelength calibration and the systematic difference between different spectrographs have to be carefully considered during radial velocity measurement. in this work, we provide a technique to correct the systematics in the wavelength calibration based on the relative radial velocity measurements from lamost mrs spectra. we show that, for the stars with multi - epoch spectra, the systematic bias which is induced from the exposures of different nights can be well corrected for lamost mrs in each spectrograph. and the precision of radial velocity zero - point of multi - epoch time - domain observations reaches below 0. 5 km / s. as a by - product, we also give the constant star candidates, which can be the secondary radial - velocity standard star candidates of lamost mrs time - domain surveys. | arxiv:2108.07483 |
the question of the renormalization scheme dependence of the $ \ tau $ semileptonic decay rate is revisited in response to a recent criticism. particular attention is payed to a distinction between a consistent quantitative description of this dependence and the actual selection of a subset of ` ` acceptable ' ' renormalization schemes. it is argued that a reasonable universal measure of the renormalization scheme dependence can be formulated, which gives encouraging results when applied to various physical quantities, including the semileptonic $ \ tau $ decay rate. | arxiv:hep-ph/9302264 |
turbulent concentric coaxial pipe flows are numerically investigated as canonical problem addressing spanwise curvature effects on heat and momentum transfer that are encountered in various engineering applications. it is demonstrated that the wall - adapting local eddy - viscosity ( wale ) model within a large - eddy simulation ( les ) framework, without model parameter recalibration, has limited predictive capabilities as signalized by poor representation of wall curvature effects and notable grid dependence. the identified lack in the modeling of radial transport processes is therefore addressed here by utilizing a stochastic one - dimensional turbulence ( odt ) model. a standalone odt formulation for cylindrical geometry is used in order to asses to which extent the predictability can be expected to improve by utilizing an advanced wall - modeling modeling strategy. it is shown that odt is capable of capturing spanwise curvature and finite reynolds number effects for fixed adjustable odt model parameters. based on the analogy of heat and mass transfer, present results yield new opportunities for modeling turbulent transfer process in chemical, process, and thermal engineering. | arxiv:2310.19800 |
we use 85 pairs of high resolution lcdm cosmological simulations from the nihao project to investigate why in dwarf galaxies neutral hydrogen ( hi ) linewidths measured at 50 % of the peak flux w _ 50 / 2 ( from the hydrodynamical simulations ) tend to underpredict the maximum circular velocity vmaxdmo ( from the corresponding dark matter only simulations ). there are two main contributing processes. 1 ) lower mass galaxies are less rotationally supported. this is confirmed observationally from the skewness of linewidths in bins of hi mass in both alfalfa and hipass observations. 2 ) the hi distributions are less extended ( relative to the dark matter halo ) in dwarf galaxies. coupled to the lower baryon - to - halo ratio results in rotation curves that are still rising at the last measured data point, in agreement with observations from sparc. combining these two effects, in both simulations and observations lower mass galaxies have on average lower w _ 50 / w _ 20. additionally, mass loss driven by supernovae and projection effects ( dwarf galaxies are in general not thin disks ) further reduce the linewidths. the implied hi linewidth velocity function from nihao is in good agreement with observations in the nearby universe of dwarf galaxies : 10 < w _ 50 / 2 < 80 km / s. the dark matter only slope of - 2. 9 is reduced to - 1. 0 in the hydro simulations. future radio observations of unbiased samples with higher spatial resolution will enable stricter tests of the simulations, and thus of the lcdm model. | arxiv:1807.10518 |
why do many modern neural - network - based graph generative models fail to reproduce typical real - world network characteristics, such as high triangle density? in this work we study the limitations of edge independent random graph models, in which each edge is added to the graph independently with some probability. such models include both the classic erd \ " { o } s - r \ ' { e } nyi and stochastic block models, as well as modern generative models such as netgan, variational graph autoencoders, and cell. we prove that subject to a bounded overlap condition, which ensures that the model does not simply memorize a single graph, edge independent models are inherently limited in their ability to generate graphs with high triangle and other subgraph densities. notably, such high densities are known to appear in real - world social networks and other graphs. we complement our negative results with a simple generative model that balances overlap and accuracy, performing comparably to more complex models in reconstructing many graph statistics. | arxiv:2111.00048 |
we propose the first unified framework unicolor to support colorization in multiple modalities, including both unconditional and conditional ones, such as stroke, exemplar, text, and even a mix of them. rather than learning a separate model for each type of condition, we introduce a two - stage colorization framework for incorporating various conditions into a single model. in the first stage, multi - modal conditions are converted into a common representation of hint points. particularly, we propose a novel clip - based method to convert the text to hint points. in the second stage, we propose a transformer - based network composed of chroma - vqgan and hybrid - transformer to generate diverse and high - quality colorization results conditioned on hint points. both qualitative and quantitative comparisons demonstrate that our method outperforms state - of - the - art methods in every control modality and further enables multi - modal colorization that was not feasible before. moreover, we design an interactive interface showing the effectiveness of our unified framework in practical usage, including automatic colorization, hybrid - control colorization, local recolorization, and iterative color editing. our code and models are available at https : / / luckyhzt. github. io / unicolor. | arxiv:2209.11223 |
associated with a chemical reaction network is a natural labelled bipartite multigraph termed an sr graph, and its directed version, the dsr graph. these objects are closely related to petri nets. the construction of sr and dsr graphs for chemical reaction networks is presented. conclusions about asymptotic behaviour of the associated dynamical systems which can be drawn easily from the graphs are discussed. in particular, theorems on ruling out the possibility of multiple equilibria or stable oscillation in chemical reaction networks based on computations on sr / dsr graphs are presented. these include both published and new results. the power and limitations of such results are illustrated via several examples. | arxiv:1005.5472 |
routing tables in ad hoc and wireless routing protocols can be represented using rooted trees. the constant need for communication and storage of these trees in routing protocols demands an efficient rooted tree coding algorithm. this efficiency is defined in terms of the average code length, and the optimality of the algorithm is measured by comparing the average code length with the entropy of the source. in this work, treeexplorer is introduced as an easy - to - implement and nearly optimal algorithm for coding rooted tree structures. this method utilizes the number of leaves of the tree as an indicator for choosing the best method of coding. we show how treeexplorer can improve existing routing protocols for ad hoc and wireless systems, which normally entails a significant communication overhead. | arxiv:2207.05626 |
looking towards first lhc collisions, the atlas detector is being commissioned using the physics data available : cosmic rays and data taken during the lhc single beam operations at 450 gev. during the installation of the atlas detector in the cavern, cosmic rays were collected with the different parts of the detector that were available. combined cosmic runs taken with the full installed detector with and without magnetic field as well as a few single beam events recently recorded are being used to commission the full system prior to the first proton collisions. | arxiv:0810.3555 |
we calculate the magnetization of the two - dimensional electron gas in a short - period lateral superlattice, with the coulomb interaction included in hartree and hartree - fock approximations. we compare the results for a finite, mesoscopic system modulated by a periodic potential, with the results for the infinite periodic system. in addition to the expected strong exchange effects, the size of the system, the type and the strength of the lateral modulation leave their fingerprints on the magnetization. | arxiv:cond-mat/9910479 |
we report on a 120 ks chandra / hetg spectrum of the black hole grs 1915 + 105. the observation was made during an extended and bright soft state in june, 2015. an extremely rich disk wind absorption spectrum is detected, similar to that observed at lower sensitivity in 2007. the very high resolution of the third - order spectrum reveals four components to the disk wind in the fe k band alone ; the fastest has a blue - shift of v = 0. 03c. broadened re - emission from the wind is also detected in the first - order spectrum, giving rise to clear accretion disk p cygni profiles. dynamical modeling of the re - emission spectrum gives wind launching radii of r ~ 10 ^ ( 2 - 4 ) gm / c ^ 2. wind density values of n ~ 10 ^ ( 13 - 16 ) cm ^ - 3 are then required by the ionization parameter formalism. the small launching radii, high density values, and inferred high mass outflow rates signal a role for magnetic driving. with simple, reasonable assumptions, the wind properties constrain the magnitude of the emergent magnetic field to b ~ 10 ^ ( 3 - 4 ) gauss if the wind is driven via magnetohydrodynamic ( mhd ) pressure from within the disk, and b ~ 10 ^ ( 4 - 5 ) gauss if the wind is driven by magnetocentrifugal acceleration. the mhd estimates are below upper limits predicted by the canonical alpha - disk model ( shakura & sunyaev 1973 ). we discuss these results in terms of fundamental disk physics and black hole accretion modes. | arxiv:1603.01474 |
following work by w \ " unsch and collaborators, we investigate a self - enrichment scenario for second generation star formation in globular clusters wherein wind material from first generation massive stars rapidly radiatively cools. radiative energy loss allows retention of fast winds within the central regions of clusters, where it fuels star formation. secondary star formation occurs in $ \ sim3 - 5 $ myr, before supernovae, producing uniform iron abundances in both populations. we derive the critical criteria for radiative cooling of massive star winds and the second generation mass as a function of cluster mass, radius, and metallicity. we derive a critical condition on $ m / r $, above which second generation star formation can occur. we speculate that above this threshold the strong decrease in the cluster wind energy and momentum allows ambient gas to remain from the cluster formation process. we reproduce large observed second generation fractions of $ \ sim30 - 80 \ % $ if wind material mixes with ambient gas. importantly, the mass of ambient gas required is only of order the first generation ' s stellar mass. second generation helium enrichment $ \ delta y $ is inversely proportional to mass fraction in the second generation ; a large second generation can form with $ \ delta y \ sim0. 001 - 0. 02 $, while a small second generation can reach $ \ delta y \ sim0. 16 $. like other self - enrichment models for the second generation, we are not able to simultaneously account for both the full range of the na - o anticorrelation and the second generation fraction. | arxiv:1704.03469 |
unparticle cosmology gives an unconventional outlook on the dark sector of cosmology, increasingly challenging $ \ lambda \ mbox { cdm } $ by $ h _ 0 $ - tension. this model derives from a finite temperature broken conformal symmetry of radiation, described by a non - radiative correction with unknown sign in energy density. this symmetry breaking has a sign ambiguity, in which corrections about the ir fixed point are normal or tachyonic. while the first has been ruled out in a recent study, the latter possesses a late - time temperature $ t _ c \ simeq 4 \, t _ { cmb } $ associated with $ \ omega _ { \ cal u } \ simeq 1 $ ( $ \ omega _ { \ cal u } \ simeq 10 ^ 4 \ omega _ { cmb } $ ), where $ t _ { cmb } $ denotes the temperature of the cosmic microwave background ( cmb ). thus exposed to the enormous heat bath of unparticles, $ t _ { cmb } $ is constrained by the astronomical age of the universe $ t _ { u, 0 } $. the relative temperature shift $ \ delta t / t $ in any heat exchange to the cmb is hereby limited to the uncertainty of a few percent in $ t _ { u, 0 } $. this bounds the effective cross - section of unparticles interactions with cmb photons to $ \ sigma _ { \ gamma \ mathcal { u } } \ lesssim 10 ^ { - 40 } \ \ mbox { m } ^ 2 = 10 ^ { - 3 } \ \ mbox { nb } $. assuming a standard cross - section across the broadband mass and energy spectrum of unparticles, a more stringent bound $ \ sigma _ { \ gamma \ mathcal { u } } \ lesssim 10 ^ { - 3 } \, \ mbox { pb } $ derives from cobe - firas constraints on spectral distortions. the first is midway of photon - neutrino $ \ sigma _ { \ gamma \ nu } $ and photon - photon cross sections $ \ sigma _ { \ gamma \ gamma } $, the second is on par with $ \ sigma _ { \ gamma \ nu } $. these constraints put late - time unparticle cosmology, if present, at the edge of the standard model. | arxiv:2203.16076 |
recently cosmic ray electrons and positrons, i. e. cosmic ray charged leptons, have been observed. to understand the distances from our solar system to the sources of such lepton cosmic rays, it is important to understand energy losses from cosmic electrodynamic fields. energy losses for ultra - relativistic electrons and / or positrons due to classical electrodynamic bremsstrahlung are computed. the energy losses considered are ( i ) due to thompson scattering from fluctuating electromagnetic fields in the background cosmic thermal black body radiation and ( ii ) due to the synchrotron radiation losses from quasi - static domains of cosmic magnetic fields. for distances to sources of galactic length proportions, the lepton cosmic ray energy must be lass than about a tev. | arxiv:1509.08365 |
explicit runge - kutta methods are classical and widespread techniques in the numerical solution of ordinary differential equations ( odes ). considering partial differential equations, spatial semidiscretisations can be used to obtain systems of odes that are solved subsequently, resulting in fully discrete schemes. however, certain stability investigations of high - order methods for hyperbolic conservation laws are often conducted only for the semidiscrete versions. here, strong stability ( also known as monotonicity ) of explicit runge - kutta methods for odes with nonlinear and semibounded ( also known as dissipative ) operators is investigated. contrary to the linear case, it is proven that many strong stability preserving ( ssp ) schemes of order two or greater are not strongly stable for general smooth and semibounded nonlinear operators. additionally, it is shown that there are first order accurate explicit ssp runge - kutta methods that are strongly stable ( monotone ) for semibounded ( dissipative ) and lipschitz continuous operators. | arxiv:1811.11601 |
magnetic imaging with nitrogen - vacancy ( nv ) spins in diamond is becoming an established tool for studying nanoscale physics in condensed matter systems. however, the optical access required for nv spin readout remains an important hurdle for operation in challenging environments such as millikelvin cryostats or biological systems. here, we demonstrate a scanning - nv sensor consisting of a diamond nanobeam that is optically coupled to a tapered optical fiber. this nanobeam sensor combines a natural scanning - probe geometry with high - efficiency through - fiber optical excitation and readout of the nv spins. we demonstrate through - fiber optically interrogated electron spin resonance and proof - of - principle magnetometry operation by imaging spin waves in an yttrium - iron - garnet thin film. our scanning - nanobeam sensor can be combined with nanophotonic structuring to control the light - matter interaction strength, and has potential for applications that benefit from all - fiber sensor access such as millikelvin systems. | arxiv:2302.12536 |
solving a long standing conjecture of erd \ h { o } s and simonovits, brandt and thomass \ ' e proved that the chromatic number of each triangle - free graph $ g $ such that $ \ delta ( g ) > | v ( g ) | / 3 $ is at most four. in fact, they showed the much stronger result that every maximal triangle - free graph $ g $ satisfying this minimum degree condition is a blow - up of either an andr \ ' asfai or a vega graph. here we establish the same structural conclusion on $ g $ under the weaker assumption that for $ m \ in \ { 2, 3, 4 \ } $ every sequence of $ 3m $ vertices has a subsequence of length $ m + 1 $ with a common neighbour. in forthcoming work this will be used to solve an old problem of andr \ ' asfai in ramsey - tur \ ' an theory. | arxiv:2406.10745 |
we calculate the differential branching fractions and angular distributions of the rare decays $ b ^ 0 \ to k ^ { * 0 } \ mu ^ + \ mu ^ - $ and $ b _ s ^ 0 \ to \ phi \ mu ^ + \ mu ^ - $, using for the first time form factors from unquenched lattice qcd. we focus on the kinematic region where the $ k ^ * $ or $ \ phi $ recoils softly ; there the newly available form factors are most precise and the nonlocal matrix elements can be included via an operator product expansion. our results for the differential branching fractions calculated in the standard model are higher than the experimental data. we consider the possibility that the deviations are caused by new physics, and perform a fit of the wilson coefficients $ c _ 9 $ and $ c _ 9 ^ \ prime $ to the experimental data for multiple $ b ^ 0 \ to k ^ { * 0 } \ mu ^ + \ mu ^ - $ and $ b _ s ^ 0 \ to \ phi \ mu ^ + \ mu ^ - $ observables. in agreement with recent results from complementary studies, we obtain $ c _ 9 - c _ 9 ^ { sm } = - 1. 0 \ pm 0. 6 $ and $ c _ 9 ^ \ prime = 1. 2 \ pm 1. 0 $, whose deviations from zero would indicate the presence of non - standard fundamental interactions. | arxiv:1310.3887 |
angle - independent, narrowband emission is required for many optoelectronic devices, ranging from high - definition displays to sensors. however, emerging materials for electroluminescent devices, such as organics and perovskites, show spectrally broad emission due to intrinsic disorder. coupling this emission to an optical resonance reduces the linewidth, but at the cost of inheriting the severe angular dispersion of the resonator. strongly coupling a dispersionless exciton state to a narrowband optical microcavity could overcome this issue ; however, electrically pumped emission from the resulting polaritons has been hampered by poor efficiencies. here, we present a universal concept for polariton - based emission from state - of - the - art organic leds ( oleds ) by introducing an assistant strong coupling layer, thus avoiding quenching - induced efficiency losses. we realize red - and green - emitting, narrowband ( fwhm < 20 nm ) and spectrally tuneable polaritonic oleds with up to 10 % external quantum efficiency and high luminance ( > 20, 000 cd m $ ^ { - 2 } $ at 5 v ). optimizing cavity detuning and coupling strength allows to achieve emission with ultralow - dispersion ( < 10 nm spectral shift at 60 { \ deg } tilt ). these results have significant implications for on - demand polariton emission and demonstrate the practical relevance of strong light - matter coupling for next - generation optoelectronics, particularly display technology. | arxiv:2207.01248 |
the problem on estimate of the koebe radius for univalent harmonic mappings of the unit disk $ \ mathbb d = \ { z \ in \ mathbb c : | z | < 1 \ } $ is considered. for a subclass of harmonic mappings with the standard normalization and a certain growth estimate for analytic dilatation, we provide new estimate for the koebe radius. new estimate for taylor coefficients of the holomorphic part of a function from the subclass under consideration is obtained as a corollary. | arxiv:2403.05526 |
the thermodynamic instability, for example the negative heat capacity, of a black hole implies the existence of off - shell negative mode ( s ) ( tachyonic mode ( s ) ) around the black hole geometry in the euclidean path integral formalism of quantum gravity. we explicitly construct an off - shell negative mode inspired from the negative heat capacity in the case of schwarzschild black hole with / without a cosmological constant. we carefully check the boundary conditions, i. e. the regularity at the horizon, the traceless condition, and the normalizability. | arxiv:1012.0441 |
the capacity region of the one - sided gaussian interference channel is established in the weak interference regime. to characterize this region, a new representation of the han - kobayashi inner bound for the one - sided gaussian interference channel is first given. next, a new outer bound on the capacity region of this channel is introduced which is tight in the weak interference regime. this is the first capacity region for any variant of the interference channel in the weak interference regime. | arxiv:1509.02200 |
modern slitless spectroscopic surveys, such as euclid and the roman space telescope, collect vast numbers of galaxy spectra but suffer from low signal - to - noise ratios. this often leads to incorrect redshift assignments when relying on a single emission line, due to noise spikes or contamination from non - target emission lines, commonly referred to as redshift interlopers. we propose a machine learning approach to correct the impact of interlopers at the level of measured summary statistics, focusing on the power spectrum monopole and line interlopers as a proof of concept. to model interloper effects, we use halo catalogs from the quijote simulations as proxies for galaxies, displacing a fraction of halos by the distance corresponding to the redshift offset between target and interloper galaxies. this yields contaminated catalogs with varying interloper fractions across a wide range of cosmologies from the quijote suite. we train a neural network on the power spectrum monopole, alone or combined with the bispectrum monopole, from contaminated mocks to estimate the interloper fraction and reconstruct the cleaned power spectrum. we evaluate performance in two settings : one with fixed cosmology and another where cosmological parameters vary under broad priors. in the fixed case, the network recovers the interloper fraction and corrects the power spectrum to better than 1 % accuracy. when cosmology varies, performance degrades, but adding bispectrum information significantly improves results, reducing the interloper fraction error by 40 - 60 %. we also study the method ' s performance as a function of the size of the training set and find that optimal strategies depend on the correlation between target and interloper samples : bispectrum information aids performance when target and interloper galaxies are uncorrelated, while tighter priors are more effective when the two are strongly correlated. | arxiv:2504.06919 |
for stochastic processes $ \ { x _ t : t \ in e \ } $, we establish sufficient conditions for the empirical process based on $ \ { i _ { x _ t \ le y } - \ operatorname { pr } ( x _ t \ le y ) : t \ in e, y \ in \ mathbb { r } \ } $ to satisfy the clt uniformly in $ t \ in e, y \ in \ mathbb { r } $. corollaries of our main result include examples of classical processes where the clt holds, and we also show that it fails for brownian motion tied down at zero and $ e = [ 0, 1 ] $. | arxiv:1008.2697 |
we investigate the steady - state transport characteristics of a quantum dot system consisting of a single energy level embedded between two reservoirs under the influence of both the temperature gradient and bias voltage. within tailored parameter regimes, the system can exhibit three counterintuitive transport phenomena of anomalous thermodiffusion, absolute negative mobility and reverse heat transport respectively. these counterintuitive phenomena do not violate the second law of thermodynamics. moreover, absolute negative mobility and reverse heat transport can be identified by a reversible energy level. these anomalous transports are different from thermoelectric transports and provide different perspectives for a more comprehensive understanding of the transport characteristics of quantum systems. | arxiv:2408.07882 |
denote by $ \ pi ( x ; q, a ) $ the number of primes $ p \ leqslant x $ with $ p \ equiv a \ bmod q. $ we prove new upper bounds for $ \ pi ( x ; q, a ) $ when $ q $ is a large prime very close to $ \ sqrt { x } $, improving upon the classical work of iwaniec ( 1982 ). the proof reduces to bounding a quintilinear sum of kloosterman sums, to which we introduce a new shifting argument inspired by vinogradov - - burgess - - karatsuba, going beyond the classical fourier - analytic approach thanks to a deep algebro - geometric result of kowalski - - michel - - sawin on sums of products of kloosterman sums. | arxiv:2504.12692 |
we comment on the role and impact of lattice fluid dynamics on the general landscape of computational fluid dynamics. starting from the historical development of lattice gas cellular automata, we move on to a cursory appraisal of the main applications of the lattice boltzmann method and challenges ahead. | arxiv:2209.13436 |
social live stream services ( slss ) exploit a new level of social interaction. one of the main challenges in these services is how to detect and prevent deviant behaviors that violate community guidelines. in this work, we focus on adult content production and consumption in two widely used slss, namely live. me and loops live, which have millions of users producing massive amounts of video content on a daily basis. we use a pre - trained deep learning model to identify broadcasters of adult content. our results indicate that moderation systems in place are highly ineffective in suspending the accounts of such users. we create two large datasets by crawling the social graphs of these platforms, which we analyze to identify characterizing traits of adult content producers and consumers, and discover interesting patterns of relationships among them, evident in both networks. | arxiv:1806.10577 |
we present analytical modelling of conical relativistic jets, in order to evaluate the role of the jet opening angle on certain key parameters that are inferred from vlbi radio observations of blazar nuclear jets. the key parameters evaluated are the orientation angle ( i. e., the viewing angle ) of the jet and the apparent speed and doppler factor of the radio knots on parsec scales. quantitative comparisons are made of the influence of the jet opening angle on the above parameters of the radio knots, as would be estimated for two widely discussed variants of relativistic nuclear jets, namely, those having uniform bulk speed and those in which the bulk lorentz factor of the flow decreases with distance from the jet axis ( a ` spine - - sheath ' flow ). our analysis shows that for both types of jet velocity distributions the expectation value of the jet orientation angle at first falls dramatically with increases in the ( central ) jet lorentz factor, but it levels off at a fraction of the opening angle for extremely relativistic jets. we also find that the effective values of the apparent speeds and doppler factors of the knots always decline substantially with increasing jet opening angle, but that this effect is strongest for ultra - relativistic jets with uniform bulk speed. we suggest that the paucity of highly superluminal parsec - scale radio components in tev blazars can be understood if their jets are highly relativistic and, being intrinsically weaker, somewhat less well collimated, in comparison to the jets in other blazars. | arxiv:0707.4023 |
we study the deformations of a smooth curve $ c $ on a smooth projective threefold $ v $, assuming the presence of a smooth surface $ s $ satisfying $ c \ subset s \ subset v $. generalizing a result of mukai and nasu, we give a new sufficient condition for a first order infinitesimal deformation of $ c $ in $ v $ to be primarily obstructed. in particular, when $ v $ is fano and $ s $ is $ k3 $, we give a sufficient condition for $ c $ to be ( un ) obstructed in $ v $, in terms of $ ( - 2 ) $ - curves and elliptic curves on $ s $. applying this result, we prove that the hilbert scheme $ \ operatorname { hilb } ^ { sc } v _ 4 $ of smooth connected curves on a smooth quartic threefold $ v _ 4 $ contains infinitely many generically non - reduced irreducible components, which are variations of mumford ' s example for $ \ operatorname { hilb } ^ { sc } \ mathbb p ^ 3 $. | arxiv:1601.07301 |
given a group \ ( g \ ), a field \ ( \ kappa \ ), and a factor set \ ( \ sigma \ ) arising from a partial projective \ ( \ kappa \ ) - representation of \ ( g \ ). this leads to the construction of a topological partial dynamical system \ ( ( \ omega _ \ sigma, g, \ hat { \ theta } ) \ ), where \ ( \ omega _ \ sigma \ ) is a compact, totally disconnected hausdorff space, and \ ( \ sigma \ ) acts as a twist for \ ( \ hat { \ theta } \ ). we show that the twisted partial group algebra \ ( \ kappa _ { par } ^ { \ sigma } g \ ) can be realized as a crossed product \ ( { \ mathscr l } ( \ omega _ \ sigma ) \ rtimes _ { ( \ hat { \ theta }, \ sigma ) } g \ ), with \ ( { \ mathscr l } ( \ omega _ \ sigma ) \ ) denoting the \ ( \ kappa \ ) - algebra of locally constant functions \ ( \ omega _ \ sigma \ to \ kappa \ ). the space \ ( \ omega _ \ sigma \ ) corresponds to the spectrum of a unital commutative subalgebra in \ ( \ kappa _ { par } ^ { \ sigma } g \ ), generated by idempotents. by describing \ ( \ omega _ \ sigma \ ) as a subspace of the bernoulli space \ ( 2 ^ g \ ), we examine conditions under which the spectral partial action \ ( \ hat { \ theta } \ ) is topologically free, impacting the ideal structure of \ ( \ kappa _ { par } ^ { \ sigma } g \ ). we further explore generating idempotent factor sets of \ ( g \ ) and present conditions on them to ensure the topological freeness of \ ( \ hat { \ theta } \ ). inspired by exel ' s semigroup \ ( \ mathcal { s } ( g ) \ ), which governs partial actions and representations of \ ( g \ ) and relates to \ ( \ kappa _ { par } g \ ), we characterize the twisted partial group algebra \ ( \ kappa _ { par } ^ { \ sigma } g \ ) as generated by a \ ( \ kappa \ ) - cancellative inverse semigroup constructed from elements of \ ( \ omega _ \ sigma \ ). | arxiv:2411.09824 |
taking into account the helicity of a massless particle, which obeys a dirac equation and is exposed to an electromagnetic field, one soon arrives at a lagrangian containing a chiral supersymmetric operator. we can even achieve an analogous result in case of an electroweak interaction. then the lagrangian contains terms that look very similar to those usually being interpreted as mass terms for the w and z bosons appearing in models of spontaneous symmetry breaking, but this time they are accompanied by neutrino fields instead of higgs fields. this invites us to a speculation that in the procedure of spontaneous symmetry breaking, neutrinos could take on the role, which we normally ascribe to the higgs bosons. | arxiv:0807.0952 |
we are beginning to see progress in language model assisted scientific discovery. motivated by the use of llms as a general scientific assistant, this paper assesses the domain knowledge of llms through its understanding of different mathematical skills required to solve problems. in particular, we look at not just what the pre - trained model already knows, but how it learned to learn from information during in - context learning or instruction - tuning through exploiting the complex knowledge structure within mathematics. motivated by the neural tangent kernel ( ntk ), we propose \ textit { ntkeval } to assess changes in llm ' s probability distribution via training on different kinds of math data. our systematic analysis finds evidence of domain understanding during in - context learning. by contrast, certain instruction - tuning leads to similar performance changes irrespective of training on different data, suggesting a lack of domain understanding across different skills. | arxiv:2405.15485 |
gas concentration detection is important for applications such as gas leakage monitoring. metal oxide ( mox ) sensors show high sensitivities for specific gases, which makes them particularly useful for such monitoring applications. however, how to efficiently sample and further process the sensor responses remains an open question. here we propose a simple analog circuit design inspired by the spiking output of the mammalian olfactory bulb and by event - based vision sensors. our circuit encodes the gas concentration in the time difference between the pulses of two separate pathways. we show that in the setting of controlled airflow - embedded gas injections, the time difference between the two generated pulses varies inversely with gas concentration, which is in agreement with the spike timing difference between tufted cells and mitral cells of the mammalian olfactory bulb. encoding concentration information in analog spike timings may pave the way for rapid and efficient gas detection, and ultimately lead to data - and power - efficient monitoring devices to be deployed in uncontrolled and turbulent environments. | arxiv:2310.07475 |
let $ p $ be a crossing - free polygon and $ \ mathcal c $ a set of shortcuts, where each shortcut is a directed straight - line segment connecting two vertices of $ p $. a shortcut hull of $ p $ is another crossing - free polygon that encloses $ p $ and whose oriented boundary is composed of elements from $ \ mathcal c $. shortcut hulls find their application in geo - related problems such as the simplification of contour lines. we aim at a shortcut hull that linearly balances the enclosed area and perimeter. if no holes in the shortcut hull are allowed, the problem admits a straight - forward solution via shortest paths. for the more challenging case that the shortcut hull may contain holes, we present a polynomial - time algorithm that is based on computing a constrained, weighted triangulation of the input polygon ' s exterior. we use this problem as a starting point for investigating further variants, e. g., restricting the number of edges or bends. we demonstrate that shortcut hulls can be used for drawing the rough extent of point sets as well as for the schematization of polygons. | arxiv:2106.13620 |
we examine the convergence in the krylov - - bogolyubov averaging for nonlinear stochastic perturbations of linear pdes with pure imaginary spectrum and show that if the involved effective equation is mixing, then the convergence is uniform in time. | arxiv:2203.15622 |
in this paper, we present a meta - algorithm intended to accelerate many existing path optimization algorithms. the central idea of our work is to strategically break up a waypoint path into consecutive groupings called " pods, " then optimize over various pods concurrently using parallel processing. each pod is assigned a color, either blue or red, and the path is divided in such a way that adjacent pods of the same color have an appropriate buffer of the opposite color between them, reducing the risk of interference between concurrent computations. we present a path splitting algorithm to create blue and red pod groupings and detail steps for a meta - algorithm that optimizes over these pods in parallel. we assessed how our method works on a testbed of simulated path optimization scenarios using various optimization tasks and characterize how it scales with additional threads. we also compared our meta - algorithm on these tasks to other parallelization schemes. our results show that our method more effectively utilizes concurrency compared to the alternatives, both in terms of speed and optimization quality. | arxiv:2106.00153 |
the ab initio full - potential linearized augmented plane - wave method explicitly designed for the slab geometry was employed to elucidate the physical origin of the layer potentials for the trilayers nfe / 3cr / nfe ( 001 ), where n is the number of fe monolayers. the thickness of the transition - metal ferromagnet has been ranged from $ n = 1 $ up to n = 8 while the spacer thickness was fixed to 3 monolayers. the calculated potentials were inserted in the fuchs - sondheimer formalism in order to calculate the giant magnetoresistance ( gmr ) ratio. the predicted gmr ratio was compared with the experiment and the oscillatory behavior of the gmr as a function of the ferromagnetic layer thickness was discussed in the context of the layer potentials. the reported results confirm that the interface monolayers play a dominant role in the intrinsic gmr. | arxiv:cond-mat/0701652 |
transferring multiple objects between bins is a common task for many applications. in robotics, a standard approach is to pick up one object and transfer it at a time. however, grasping and picking up multiple objects and transferring them together at once is more efficient. this paper presents a set of novel strategies for efficiently grasping multiple objects in a bin to transfer them to another. the strategies enable a robotic hand to identify an optimal ready hand configuration ( pre - grasp ) and calculate a flexion synergy based on the desired quantity of objects to be grasped. this paper also presents an approach that uses the markov decision process ( mdp ) to model the pick - transfer routines when the required quantity is larger than the capability of a single grasp. using the mdp model, the proposed approach can generate an optimal pick - transfer routine that minimizes the number of transfers, representing efficiency. the proposed approach has been evaluated in both a simulation environment and on a real robotic system. the results show the approach reduces the number of transfers by 59 % and the number of lifts by 58 % compared to an optimal single object pick - transfer solution. | arxiv:2112.09829 |
given positive integers $ n $ and $ d $, let $ a _ 2 ( n, d ) $ denote the maximum size of a binary code of length $ n $ and minimum distance $ d $. the well - known gilbert - varshamov bound asserts that $ a _ 2 ( n, d ) \ geq 2 ^ n / v ( n, d - 1 ) $, where $ v ( n, d ) = \ sum _ { i = 0 } ^ { d } { n \ choose i } $ is the volume of a hamming sphere of radius $ d $. we show that, in fact, there exists a positive constant $ c $ such that $ $ a _ 2 ( n, d ) \ geq c \ frac { 2 ^ n } { v ( n, d - 1 ) } \ log _ 2 v ( n, d - 1 ) $ $ whenever $ d / n \ le 0. 499 $. the result follows by recasting the gilbert - varshamov bound into a graph - theoretic framework and using the fact that the corresponding graph is locally sparse. generalizations and extensions of this result are briefly discussed. | arxiv:math/0404325 |
the paper has been withdrawn by the author since the protocol is not new. it is just the oldest version of bb84. | arxiv:quant-ph/0110053 |
the resonant period drop observed at low temperatures in torsional oscillators containing solid helium had been interpreted as a signature of supersolid. however, it was found that the shear modulus increase found in solid helium at the same low temperature could also decrease the resonant period of the torsional oscillator. we report the results of a study in two different torsional oscillators that were specially designed to minimize the shear modulus effect and maximize any possible supersolid response. we were able to place an upper limit on the nonclassical rotational inertia or supersolid fraction of $ 4 \ times10 ^ { - 6 } $. moreover, we have repeated an earlier experiment on hcp $ ^ 3 $ he solid, which shows similar low temperature stiffening as in hcp $ ^ 4 $ he. we found that the small drop of the resonant period measured in the hcp $ ^ 3 $ he sample is comparable in size to that found in the hcp $ ^ 4 $ he samples. these results strongly suggest that the resonant period drop reported in most torsional oscillator studies in the last decade is primarily a consequence of the shear modulus stiffening effect. | arxiv:1407.2132 |
= overview = = compared to normalized scientific notation, one disadvantage of using si prefixes and engineering notation is that significant figures are not always readily apparent when the smallest significant digit or digits are 0. for example, 500 μm and 500×10−6 m cannot express the uncertainty distinctions between 5×10−4 m, 5. 0×10−4 m, and 5. 00×10−4 m. this can be solved by changing the range of the coefficient in front of the power from the common 1 – 1000 to 0. 001 – 1. 0. in some cases this may be suitable ; in others it may be impractical. in the previous example, 0. 5 mm, 0. 50 mm, or 0. 500 mm would have been used to show uncertainty and significant figures. it is also common to state the precision explicitly, such as " 47 kω±5 % " another example : when the speed of light ( exactly 299792458 m / s by the definition of the meter ) is expressed as 3. 00×108 m / s or 3. 00×105 km / s then it is clear that it is between 299500 km / s and 300500 km / s, but when using 300×106 m / s, or 300×103 km / s, 300000 km / s, or the unusual but short 300 mm / s, this is not clear. a possibility is using 0. 300×109 m / s or 0. 300 gm / s. on the other hand, engineering notation allows the numbers to explicitly match their corresponding si prefixes, which facilitates reading and oral communication. for example, 12. 5×10−9 m can be read as " twelve - point - five nanometers " ( 10−9 being nano ) and written as 12. 5 nm, while its scientific notation equivalent 1. 25×10−8 m would likely be read out as " one - point - two - five times ten - to - the - negative - eight meters ". engineering notation, like scientific notation generally, can use the e notation, such that 3. 0×10−9 can be written as 3. 0e−9 or 3. 0e−9. the e ( or e ) should not be confused with the euler ' s number e or the symbol for the exa - prefix. = = binary engineering notation = = just like decimal engineering notation can be viewed as a base - 1000 scientific notation ( 103 | https://en.wikipedia.org/wiki/Engineering_notation |
recently, with the support of mobile cloud computing, a large number of health related data collected from various body sensor networks can be managed efficiently. however, to ensure data security and data privacy in cloud - integrated body sensor networks is an important and challenging issue. in this paper, we present a novel secure access control mechanism mask certificate attribute based encryption for cloud integrated body sensor networks. a specific signature is designed to mask the plaintext, then the masked data can be securely outsourced to cloud severs. an authorization certificate composing of the signature and related privilege items is constructed that is used to grant privileges to data receivers. to ensure security, a unique value is chosen to mask the certificate for each data receiver. the analysis shows that the proposed scheme has less computational cost and storage cost compared with other popular models. | arxiv:1811.07864 |
we present an alternative technique for measuring the precursor masses of transient events in stars undergoing late stage stellar evolution. we use the well - established techniques of stellar population modeling to age - date the stars surrounding the site of the recent transient event in ngc 300 ( ngc 300 ot2008 - 1 ). the surrounding stars must share a common turnoff mass with the transient, since almost all stars form in stellar clusters that remain physically associated for periods longer than the lifetime of the most massive stars. we find that the precursor of ngc 300 ot2008 - 1 is surrounded by stars that formed in a single burst between 8 - 13 myr ago, with 70 % confidence. the transient was therefore likely to be due to a progenitor whose mass falls between the main sequence turnoff mass ( 12 msun ) and the maximum stellar mass ( 25 msun ) found for isochrones bounding this age range. we characterize the general applicability of this technique in identifying precursor masses of historic and future transients and supernovae ( sne ), noting that it requires neither precursor imaging nor sub - arcsecond accuracy in the position of the transient. it is also based on the well - understood physics of the main sequence, and thus may be a more reliable source of precursor masses than fitting evolutionary tracks to precursor magnitudes. we speculate that if the progenitor mass is close to 17 msun, there may be a connection between optical transients such as ngc 300 ot2008 - 1 and the missing type ii - p sne, known as the " red supergiant problem. " | arxiv:0907.0710 |
it has recently been shown that it is not possible to impose the lorentz gauge condition in a cosmological space - time using the gutpa - bleuler method of quantization. it was also shown that it is possible to add $ \ nabla _ { \ mu } a ^ { \ mu } $ as a new degree of freedom to the electromagnetic field and that this new degree of freedom might be the dark energy which is producing the accelerated expansion of the universe. in this paper i show that the lorentz gauge condition can be imposed using dirac ' s method of quantizing constrained dynamical systems. i also compute the vacuum expectation value of the energy - momentum tensor and show that it vanishes. thus, in dirac ' s approach, the electromagnetic field does not make a contribution to the dark energy. | arxiv:1301.0032 |
policy evaluation is a key process in reinforcement learning ( rl ). it assesses a given policy by estimating the corresponding value function. when using parameterized value functions, common approaches minimize the sum of squared bellman temporal - difference errors and receive a point - estimate for the parameters. kalman - based and gaussian - processes based frameworks were suggested to evaluate the policy by treating the value as a random variable. these frameworks can learn uncertainties over the value parameters and exploit them for policy exploration. when adopting these frameworks to solve deep rl tasks, several limitations are revealed : excessive computations in each optimization step, difficulty with handling batches of samples which slows training and the effect of memory in stochastic environments which prevents off - policy learning. in this work, we discuss these limitations and propose to overcome them by an alternative general framework, based on the extended kalman filter. we devise an optimization method, called kalman optimization for value approximation ( kova ) that can be incorporated as a policy evaluation component in policy optimization algorithms. kova minimizes a regularized objective function that concerns both parameter and noisy return uncertainties. we analyze the properties of kova and present its performance on deep rl control tasks. | arxiv:2002.07171 |
when ions are crowded, the effect of steric repulsion between ions becomes significant and the conventional poisson - - boltzmann ( pb ) equation ( without steric effect ) should be modified. for this purpose, we study the asymptotic limit of steady state poisson - - nernst - - planck equations with steric effects ( pnp - steric equations ). by the assumptions of steric effects, we transform steady state pnp - steric equations into a pb equation with steric effects ( pb - steric equation ) which has a parameter $ \ lambda $ and positive constants $ \ lambda _ i $ ' s ( depend on the radii of ions and solvent molecules ). the nonlinear term of pb - steric equation is mainly determined by a lambert type function which represents the concentration of solvent molecules. as $ \ lambda = 0 $, the pb - steric equation becomes the conventional pb equation but as $ \ lambda > 0 $, a large $ \ lambda $ makes the steric repulsion ( between ions and solvent molecules ) stronger. this motivates us to find the asymptotic limit of pb - steric equation as $ \ lambda $ goes to infinity. under the robin ( or neumann ) boundary condition, we prove theoretically and numerically that the pb - steric equation has a unique solution $ \ phi _ \ lambda $ which converges to solution $ \ phi ^ * $ of a modified pb ( mpb ) equation as $ \ lambda $ tends to infinity. our results show that the limiting equation of pb - steric equation ( as $ \ lambda $ goes to infinity ) is a mpb equation which has the same form ( up to scalar multiples ) as those mpb equations in \ cite { 1942bikerman, 1997borukhov, 2007kilic, 2009li, 2009li2, 2013li, 2011lu }. therefore, the pb - steric equation can be regarded as a generalized model of mpb equations. | arxiv:2205.12513 |
this work deals with chaos suppression based on average of the rounded modes to negative and positive infinite. the present procedure acts to reduce the rounding errors. it was observed that when the method proposed in this paper is applied to the chaotic lorenz ' s system, it exhibits a periodic behaviour, characterized by a limit cycle and negative largest lyapunov exponent. we tested our approach using three discretization schemes based on runge - kutta method | arxiv:1711.09298 |
van der waals heterostructures composed of multiple few layer crystals allow the engineering of novel materials with predefined properties. as an example, coupling graphene weakly to materials with large spin orbit coupling ( soc ) allows to engineer a sizeable soc in graphene via proximity effects. the strength of the proximity effect depends on the overlap of the atomic orbitals, therefore, changing the interlayer distance via hydrostatic pressure can be utilized to enhance the interlayer coupling between the layers. in this work, we report measurements on a graphene / wse $ _ 2 $ heterostructure exposed to increasing hydrostatic pressure. a clear transition from weak localization to weak anti - localization is visible as the pressure increases, demonstrating the increase of induced soc in graphene. | arxiv:2103.13325 |
we consider complex - valued solutions of the three - dimensional navier - stokes system without external forcing on $ r ^ 3 $. we show that there exists an open set in the space of 10 - parameter families of initial conditions such that for each family from this set there are values of parameters for which the solution develops blow up in finite time. | arxiv:physics/0610101 |
hot massive stars exhibit strong stellar winds that enrich the surrounding interstellar medium and affect the stars ' evolution. however, the winds are inhomogeneous ( clumped ) and are difficult to model in radiative transfer codes. to produce more realistic spectra many codes use a volume - filling factor approach to incorporate the effects of clumping. while this approach is convenient it is simplistic. we introduce an alternative approach to incorporate clumping by assuming the wind is composed of dense spherical shells. using this approach in the radiative transfer code cmfgen we produce synthetic spectra for azv83, an o7iaf + supergiant located in the small magellanic cloud. the spectrum of azv83 is rich in both photospheric and wind features, making it an ideal candidate with which to investigate the physical characteristics of stellar winds. synthetic spectra are compared to the star ' s observed spectrum to better characterize the influence of clumped winds on spectral features, and to better understand the limitations of the volume - filling factor approach. the approach using spherical shells yields similar wind parameters to those obtained using the volume - filling factor approach although a slightly higher mass - loss rate is required to fit h $ \ alpha $. as expected, the interclump medium in the model with shells allows the high ionisation resonance transitions of n v and o vi to be fitted using $ l _ { \ rm x - ray } / l _ { \ rm bol } \ approx 10 ^ { - 7 } $ which is typically observed for o stars, and which is a factor of ten lower than needed with the volume - filling factor approach. | arxiv:2103.07495 |
the lorentz - invariance - violating weyl and dirac fermions have recently attracted intensive interests as new types of particles beyond high - energy physics, and they demonstrate novel physical phenomena such as angle - dependent chiral anomaly and topological lifshitz transition. here we predict the existence of lorentz - invariance - violating dirac fermions in the ypd $ _ 2 $ sn class of heusler alloys that emerge at the boundary between the electron - like and hole - like pockets in the brillouin zone, based on the first - principles electronic structure calculations. in combination with the fact that this class of materials was all reported to be superconductors, the ypd $ _ 2 $ sn class provides an appropriate platform for studying exotic physical properties distinguished from conventional dirac fermions, especially for realizing possible topological superconductivity. | arxiv:1612.07456 |
inverse problems, i. e., estimating parameters of physical models from experimental data, are ubiquitous in science and engineering. the bayesian formulation is the gold standard because it alleviates ill - posedness issues and quantifies epistemic uncertainty. since analytical posteriors are not typically available, one resorts to markov chain monte carlo sampling or approximate variational inference. however, inference needs to be rerun from scratch for each new set of data. this drawback limits the applicability of the bayesian formulation to real - time settings, e. g., health monitoring of engineered systems, and medical diagnosis. the objective of this paper is to develop a methodology that enables real - time inference by learning the bayesian inverse map, i. e., the map from data to posteriors. our approach is as follows. we parameterize the posterior distribution as a function of data. this work outlines two distinct approaches to do this. the first method involves parameterizing the posterior using an amortized full - rank gaussian guide, implemented through neural networks. the second method utilizes a conditional normalizing flow guide, employing conditional invertible neural networks for cases where the target posterior is arbitrarily complex. in both approaches, we learn the network parameters by amortized variational inference which involves maximizing the expectation of evidence lower bound over all possible datasets compatible with the model. we demonstrate our approach by solving a set of benchmark problems from science and engineering. our results show that the posterior estimates of our approach are in agreement with the corresponding ground truth obtained by markov chain monte carlo. once trained, our approach provides the posterior distribution for a given observation just at the cost of a forward pass of the neural network. | arxiv:2305.20004 |
we analyze the simultaneous time - optimal control of two - spin systems. the two non coupled spins which differ in the value of their chemical offsets are controlled by the same magnetic fields. using an appropriate rotating frame, we restrict the study to the case of opposite shifts. we then show that the optimal solution of the inversion problem in a rotating frame is composed of a pulse sequence of maximum intensity and is similar to the optimal solution for inverting only one spin by using a non - resonant control field in the laboratory frame. an example is implemented experimentally using techniques of nuclear magnetic resonance. | arxiv:1009.1077 |
the novelty of the current work is precisely to propose a statistical procedure to combine estimates of the modal parameters provided by any set of operational modal analysis ( oma ) algorithms so as to avoid preference for a particular one and also to derive an approximate joint probability distribution of the modal parameters, from which engineering statistics of interest such as mean value and variance are readily provided. the effectiveness of the proposed strategy is assessed considering measured data from an actual centrifugal compressor. the statistics obtained for both forward and backward modal parameters are finally compared against modal parameters identified during standard stability verification testing ( svt ) of centrifugal compressors prior to shipment, using classical experimental modal analysis ( ema ) algorithms. the current work demonstrates that combination of oma algorithms can provide quite accurate estimates for both the modal parameters and the associated uncertainties with low computational costs. | arxiv:2407.07273 |
this paper is a step in our program for proving the piece - birkhoff conjecture for regular rings of any dimension ( this would contain, in particular, the classical pierce - birkhoff conjecture which deals with polynomial rings over a real closed field ). we first recall the connectedness and the definable connectedness conjectures, both of which imply the pierce - birkhoff conjecture. then we introduce the notion of a system of approximate roots of a valuation v on a ring a ( that is, a collection q of elements of a such that every v - ideal is generated by products of elements of q ). we use approximate roots to give explicit formulae for sets in the real spectrum of a which we strongly believe to satisfy the conclusion of the definable connectedness conjecture. we prove this claim in the special case of dimension 2. this proves the pierce - birkhoff conjecture for arbitrary regular 2 - dimensional rings. | arxiv:1003.1188 |
molecular communication ( mc ) is a model of information transmission where the signal is transmitted by information - carrying molecules through their physical transport from a transmitter to a receiver through a communication channel. prior efforts have identified suitable " information molecules " whose efficacy for signal transmission has been studied extensively in diffusive channels ( dc ). although easy to implement, dcs are inefficient for distances longer than tens of nanometers. in contrast, molecular motor - driven nonequilibrium or active transport can drastically increase the range of communication and may permit efficient communication up to tens of micrometers. in this paper, we investigate how active transport influences the efficacy of molecular communication, quantified by the mutual information between transmitted and received signals. we consider two specific scenarios : ( a ) active transport through relays and ( b ) active transport through a mixture of active and diffusing particles. in each case, we discuss the efficacy of the communication channel and discuss their potential pitfalls. | arxiv:2410.19411 |
in 2012, bilicki and seikel ( arxiv : 1206. 5130 ) showed that $ h ( z ) $ data reconstructed using gaussian process regression from cosmic chronometers and bao, conclusively rules out the $ r _ h = ct $ model. these results were disputed by melia and collaborators in two different works ( arxiv : 1304. 1802 and arxiv : 1802. 02255 ), who showed using both an unbinned analysis and gaussian process reconstructed $ h ( z ) $ data from chronometers, that $ r _ h = ct $ is favored over $ \ lambda $ cdm model. to resolve this imbroglio, we carry out model comparison of $ \ lambda $ cdm versus $ r _ h = ct $ by independently reproducing the above claims using latest chronometer data. we perform model selection between these two models using bayesian model comparison. we find that no one model between $ \ lambda $ cdm and $ r _ h = ct $ is decisively favored when uniform priors on $ \ lambda $ cdm parameters are used. however, if we use priors centered around the planck best - fit values, then $ \ lambda $ cdm is very strongly preferred over $ r _ h = ct $. | arxiv:2003.00494 |
priced timed games are optimal - cost reachability games played between two players - - - the controller and the environment - - - by moving a token along the edges of infinite graphs of configurations of priced timed automata. the goal of the controller is to reach a given set of target locations as cheaply as possible, while the goal of the environment is the opposite. priced timed games are known to be undecidable for timed automata with $ 3 $ or more clocks, while they are known to be decidable for automata with $ 1 $ clock. in an attempt to recover decidability for priced timed games bouyer, markey, and sankur studied robust priced timed games where the environment has the power to slightly perturb delays proposed by the controller. unfortunately, however, they showed that the natural problem of deciding the existence of optimal limit - strategy - - - optimal strategy of the controller where the perturbations tend to vanish in the limit - - - is undecidable with $ 10 $ or more clocks. in this paper we revisit this problem and improve our understanding of the decidability of these games. we show that the limit - strategy problem is already undecidable for a subclass of robust priced timed games with $ 5 $ or more clocks. on a positive side, we show the decidability of the existence of almost optimal strategies for the same subclass of one - clock robust priced timed games by adapting a classical construction by bouyer at al. for one - clock priced timed games. | arxiv:1507.05787 |
iiizw2 was observed with xmm - newton in july 2000. its x - ray spectrum can be described by a powerlaw of photon index gamma = 1. 7 with a gaussian line at 6. 7 kev. there is no significant evidence of intrinsic absorption within the source or of a soft x - ray excess. multi - wavelength light curves over a period of 25 years show related variations from the radio to the x - rays. we interpret the radio to optical emission as synchrotron radiation, self - absorbed in the radio / millimeter region, and the x - rays as mainly due to compton up - scattering of low - energy photons by the population of high - energy electrons that give rise to the synchrotron radiation. | arxiv:astro-ph/0201545 |
in this work we will review the notion of topological complexity, introduced by michael farber in 2003. we will use this theory of topological complexity to solve the motion planning problem of a mobile robot that navigates in the euclidean plane avoiding colliding with an obstacle. specifically, we calculate topological complexity and design explicit algorithms. | arxiv:2105.07980 |
major at sogang university creative technology degree at university of twente art and technology studies at school of the art institute of chicago | https://en.wikipedia.org/wiki/Creative_technology |
we present a proposal for a one - bit full - adder to process classical information based on the quantum reversible dynamics of a triple quantum dot system. the device works via the repeated execution of a fredkin gate implemented through the dynamics of a single time - independent hamiltonian. our proposal uses realistic parameter values and could be implemented on currently available quantum dot architectures. we compare the estimated energy requirements for operating our full - adder with those of well - known fully classical devices, and argue that our proposal may provide a consistently better energy efficiency. our work serves as a proof of principle for the development of energy - efficient information technologies operating through coherent quantum dynamics. | arxiv:2206.14241 |
chatgpt has established generative ai ( genai ) as a significant technological advancement. however, genai ' s intricate relationship with competing platforms and its downstream impact on users remains under - explored. this paper initiates the study of genai ' s long - term social impact resulting from the weakening network effect of human - based platforms like stack overflow. first, we study genai ' s revenue - maximization optimization problem. we develop an approximately optimal solution and show that the optimal solution has a non - cyclic structure. then, we analyze the social impact, showing that genai could be socially harmful. specifically, we present an analog to braess ' s paradox in which all users would be better off without genai. finally, we develop necessary and sufficient conditions for a regulator with incomplete information to ensure that genai is socially beneficial. | arxiv:2409.05506 |
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