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in this paper the early stages of the self - catalyzed vapor - liquid - solid ( vls ) growth of gaas nanowires on epi - ready si substrates by molecular beam epitaxy ( mbe ) are studied. the interaction of ga nano - droplets ( nds ) with the silica overlayer is investigated by x - ray photoemission spectroscopy ( xps ) and atomic force microscopy ( afm ). we show how ga nds drill the silica overlayer and make contact with bulk si to allow gaas nanowires ( nws ) epitaxial growth by studying each of the three steps of the nw growth process sequentially : ga nds pre - deposition, post - deposition annealing to reach the nw growth temperature, and finally nw growth itself. the pre - deposition temperature allows to control the density and morphology of the nds. a high enough annealing temperature enhances the reduction of siox by ga oxidation and leads to the formation of holes which is seen by a new component in xps spectra, assumed to be the consequence of the ga - si interaction. finally, these nano - holes act as nucleation sites for the epitaxial gaas vls growth. during the gaas growth, three different chemical environments of ga are identified in ga2p core level : metallic ga due to the droplets at the top of the nws, ga oxide in contact with the siox overlayer and ga arsenide from nws.
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arxiv:1910.14570
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a comprehensive study of impurity - induced magnetism in nonmagnetically ( mg $ { } ^ { 2 + } $ ) and magnetically ( co $ { } ^ { 2 + } $ ) doped pbni $ { } _ { 2 } $ v $ { } _ { 2 } $ o $ { } _ { 8 } $ compounds is given, using both macroscopic dc susceptibility and local - probe electron spin resonance ( esr ) techniques. magnetic coupling between impurity - liberated spins is estimated from a linewidth of low - temperature esr signal in mg - doped samples. in addition, in the case of magnetic cobalt dopants the impurity - host magnetic exchange is evaluated from the co - induced contribution to the linewidth in the paramagnetic phase. the experimentally observed severe broadening of the esr lines in the magnetically doped compounds with respect to nonmagnetic doping is attributed to a rapid spin - lattice relaxation of the co $ { } ^ { 2 + } $ ions, which results in a bottleneck - type of temperature dependence of the induced linewidth. the exchange parameters obtained from the esr analysis offer a satisfactory explanation of the observed low - temperature magnetization in doped samples.
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arxiv:cond-mat/0506056
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, making mda one of the world ' s leading communication satellite companies. 2014 : acquired the advanced systems business line ( formerly erim international ) of general dynamics advanced information systems division. 2017 : completed its acquisition of digitalglobe, mda now will be named maxar technologies, dual - listed on nyse and tsx. mda will then be a subsidiary of us - based maxar by 2019. 2018 : announced acquisition of neptec for $ 32 million. 2019 : completed u. s. domestication, changing the parent company ' s incorporation from canada to delaware, usa. 2020 : mda is sold to a consortium of canadian investors led by northern private capital. this sale includes the houston - based mda us systems, llc. 2020 : completed its acquisition of vricon, inc for $ 140 million. vricon is a global leader in satellite - derived 3d data for defense and intelligence markets 2022 : maxar to be taken private through an acquisition led by advent international, in a cash deal worth $ 6. 4 billion. the acquisition completed in may 2023. 2024 : maxar intelligence launches worldview legion a fleet of six high - performing satellites that dramatically expanded the ability to revisit the most rapidly changing areas on earth, enabling more near - time insights. 2025 : maxar shuts down access to satellite images in ukraine following request from the trump administration. 2025 : came under scrutiny for pahalgam imagery orders and prior partnership with bsi, a pakistani firm flagged by u. s. homeland security for selling satellite data to pakistan ’ s government. = = see also = = bombardier aerospace com dev international cmc electronics heroux - devtek mda space missions spar aerospace viking air = = references = = = = external links = = official website
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https://en.wikipedia.org/wiki/Maxar_Technologies
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we present the results of our identification of 17 x - ray sources detected in the 4 - 12 kev energy range by the mikhail pavlinsky art - xc telescope during the first year of the srg all - sky survey. three of them have been discovered by the art - xc telescopes, while the remaining ones have already been known previously as x - ray sources, but their nature has remained unknown. we took optical spectra for nine sources located in the northern sky $ \ delta > - 20 $ deg with the 1. 6 - m azt - 33ik telescope at the sayan observatory ( the institute of solar - terrestrial physics, the siberian branch of the russian academy of sciences ) and the 1. 5 - m russian - turkish telescope at the tubitak national observatory. for the remaining objects we have analyzed the archival optical spectra taken during the 6df survey. all of the investigated objects have turned out to be seyfert galaxies ( eight of type 1, seven of type 2, and two of intermediate type 1. 8 ) at redshifts up to $ z \ approx 0. 15 $. based on data from the erosita and art - xc telescopes onboard the srg observatory, we have obtained x - ray spectra in the energy range 0. 2 - 20 kev for eight sources. a significant intrinsic absorption ( $ n _ h > 10 ^ { 22 } $ cm $ ^ { - 2 } $ ) has been detected in three of them, with two of them being probably strongly absorbed ( $ n _ h \ sim 10 ^ { 23 } $ cm $ ^ { - 2 } $ ). this paper is a continuation of the series of publications on the optical identification of active galactic nuclei detected by the art - xc telescope.
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arxiv:2208.10963
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the classical theorem of erd \ h os \ & wintner furnishes a criterion for the existence of a limiting distribution for a real, additive arithmetical function. this work is devoted to providing an effective estimate for the remainder term under the assumption that the conditions in the criterion are fulfilled. we also investigate the case of a conditional distribution.
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arxiv:2002.07475
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this paper establishes a mathematical proof of the blue - shift instability at the sub - extremal kerr cauchy horizon for the linearised vacuum einstein equations. more precisely, we exhibit conditions on the $ s = + 2 $ teukolsky field, consisting of suitable integrated upper and lower bounds on the decay along the event horizon, that ensure that the teukolsky field, with respect to a frame that is regular at the cauchy horizon, becomes singular. the conditions are in particular satisfied by solutions of the teukolsky equation arising from generic and compactly supported initial data by the recent work [ 51 ] of ma and zhang for slowly rotating kerr.
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arxiv:2201.12295
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zipf ' s law seems to be ubiquitous in human languages and appears to be a universal property of complex communicating systems. following the early proposal made by zipf concerning the presence of a tension between the efforts of speaker and hearer in a communication system, we introduce evolution by means of a variational approach to the problem based on kullback ' s minimum discrimination of information principle. therefore, using a formalism fully embedded in the framework of information theory, we demonstrate that zipf ' s law is the only expected outcome of an evolving, communicative system under a rigorous definition of the communicative tension described by zipf.
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arxiv:1008.0938
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a cognitive fully adaptive radar ( cofar ) adapts its behavior on its own within a short period of time in response to changes in the target environment. for the cofar to function properly, it is critical to understand its operating environment through estimation of the clutter channel impulse response ( ccir ). in general, ccir is sparse but prior works either ignore it or estimate the ccir by imposing sparsity as an explicit constraint in their optimization problem. in this paper, contrary to these studies, we develop covariance - free bayesian learning ( cofbl ) techniques for estimating sparse ccir in a cofar system. in particular, we consider a multiple measurement vector scenario and estimate a simultaneously sparse ( row sparse ) ccir matrix. our cofbl framework reduces the complexity of conventional sparse bayesian learning through the use of the diagonal element estimation rule and conjugate gradient descent algorithm. we show that the framework is applicable to various forms of ccir sparsity models : group, joint, and joint - cum - group. we evaluate our method through numerical experiments on a data set generated using rfview, a high - fidelity modeling and simulation tool. we derive bayesian cram \ ' { e } r - rao bounds for the various considered scenarios to benchmark the performance of our algorithms. our results demonstrate that the proposed cofbl - based approaches perform better than the existing popular approaches such as multiple focal underdetermined system solver and simultaneous orthogonal matching pursuit.
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arxiv:2408.06078
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in unsupervised machine learning, agreement between partitions is commonly assessed with so - called external validity indices. researchers tend to use and report indices that quantify agreement between two partitions for all clusters simultaneously. commonly used examples are the rand index and the adjusted rand index. since these overall measures give a general notion of what is going on, their values are usually hard to interpret. three families of indices based on counting object pairs are analyzed. it is shown that the overall indices can be decomposed into indices that reflect the degree of agreement on the level of individual clusters. the overall indices based on the pair - counting approach are sensitive to cluster size imbalance : they tend to reflect the degree of agreement on the large clusters and provide little to no information on smaller clusters. furthermore, the value of rand - like indices is determined to a large extent by the number of pairs of objects that are not joined in either of the partitions.
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arxiv:1901.01777
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large - amplitude density perturbations may have collapsed during the radiation dominated epoch of the universe to form primordial black holes ( pbhs ). there are several constraints to the abundance of pbhs that stem from evaporation or gravitational effects. due to the connection between primordial perturbations and the formation of pbhs, constraints on the present - day abundance of pbhs can be translated into limits on the primordial curvature power spectrum. we introduce several new observational and forecasted constraints to the amplitude of the primordial power spectrum and incorporate in our analysis uncertainties in the critical overdensity for collapse and considerations of ellipsoidal collapse. our results provide the most stringent limits from pbhs on the primordial curvature power spectrum on small scales.
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arxiv:1904.10971
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we present a measurement of the asymmetry $ a _ { cp } $ between same - sign inclusive dilepton samples $ \ ell ^ + \ ell ^ + $ and $ \ ell ^ - \ ell ^ - $ ( $ \ ell = e, \ mu $ ) from semileptonic b decays in y ( 4s ) - - > bbbar events, using the complete data set recorded by the babar experiment near the y ( 4s ) resonance, corresponding to 471 million bbbar pairs. the asymmetry a _ { cp } allows comparison between the mixing probabilities p ( b0bar - - > b0 ) and p ( b0 - - > b0bar ), and therefore probes cp and t violation. the result, $ a _ { cp } = ( - 3. 9 \ pm 3. 5 ( stat ) \ pm 1. 9 ( syst ) ) \ times 10 ^ { - 3 } $, is consistent with the standard model expectation.
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arxiv:1411.1842
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recently the cdf collaboration has reported the excess in the dijet invariant - mass distribution of the wjj events, corresponding to a significance of 3. 2 standard deviations. considering the lack of similar excesses in the $ \ gamma jj $ and $ z jj $ events yet, we propose a new z ' model : z ' couples only to the second generation quarks. single production of $ \ zsc $ as well as associated production with $ w, \ gamma, z $ are mainly from the sea quarks. only $ w z ' $ production has additional contribution from one valence quark and one sea quark, which is allowed by ckm mixing. we found that if the new gauge coupling is large enough, marginally permitted by perturbativity, this new model can explain the observed cdf $ wjj $ anomaly as well as the lack of $ \ gm jj $ and $ z jj $ anomalies. vanishing coupling of z ' - b - b protects this model from the constraint of p pbar - > wh - > l \ nu b \ bar { b }.
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arxiv:1104.4560
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this paper analytically investigates the darcy - poisson - nernst - planck system. this system is a mathematical model for electrolyte solutions. in this paper, we consider electrolyte solutions, which consist of a neutral fluid and two suspended oppositely charged chemical species with arbitrary valencies z _ 1 > 0 > z _ 2. we prove global existence and uniqueness of weak solutions in two space dimensions and three space dimensions. so far, most of the existence results have been proven for symmetric electrolyte solutions. these solutions consist of a neutral fluid and two suspended charged chemical species with symmetric valencies + / - z. as many electrolyte solutions in biological applications and hydrodynamical applications are not symmetric, the presented extension of the previous existence results is an important step.
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arxiv:1605.07396
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identification of crack positions or anomalies in materials using the time reversal based nonlinear elastic wave spectroscopy ( tr - news ) is an established method. we propose a system using transducers which emit forward propagating solitonic wave and time - reversed propagating solitonic wave produced by memristers placed on a side of a rectangle and scattered by cracks in the material and received by receivers which are placed on the opposite side of the rectangle. by minimizing the difference of the scattered forward propagating wave and the scattered tr wave, we get information of the position of the crack by using the neural network technique. route of the solitons are expressed by 2 dimensional projective quaternion functions, and parameters for getting the optimal route from signals are expected to be reduced. we consider the wave is expressed by a soliton which is conformal, and discuss symmetry protected topological impurities and gravitational effects using the atiyah - patodi - singer ' s index theorem.
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arxiv:2010.09487
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we consider an evolution problem associated to the kazdan - warner equation on a closed riemann surface $ ( \ sigma, g ) $ \ begin { align * } - \ delta _ { g } u = 8 \ pi \ left ( \ frac { he ^ { u } } { \ int _ { \ sigma } he ^ { u } { \ rm d } \ mu _ { g } } - \ frac { 1 } { \ int _ { \ sigma } { \ rm d } \ mu _ { g } } \ right ) \ end { align * } where the prescribed function $ h \ geq0 $ and $ \ max _ { \ sigma } h > 0 $. we prove the global existence and convergence under additional assumptions such as \ begin { align * } \ delta _ { g } \ ln h ( p _ 0 ) + 8 \ pi - 2k ( p _ 0 ) > 0 \ end { align * } for any maximum point $ p _ 0 $ of the sum of $ 2 \ ln h $ and the regular part of the green function, where $ k $ is the gaussian curvature of $ \ sigma $. in particular, this gives a new proof of the existence result by yang and zhu [ proc. amer. math. soc. 145 ( 2017 ), no. 9, 3953 - 3959 ] which generalizes existence result of ding, jost, li and wang [ asian j. math. 1 ( 1997 ), no. 2, 230 - 248 ] to the non - negative prescribed function case.
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arxiv:2005.01141
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in phase transition phenomena, the estimation of the critical point is crucial for the calculation of the various critical exponents and the determination of the universality class they belong to. however, this is not an easy task, since a huge amount of realizations is needed to eliminate the noise in the data. in this paper, we introduce a novel method for the simultaneous estimation of the critical point $ p _ c $ and the critical exponent $ \ beta / \ nu $, applied for the case of " explosive " bond percolation on $ 2d $ square lattices and er networks. the results show that with only a few hundred of realizations, it is possible to acquire accurate values for these quantities. guidelines are given at the end for the applicability of the method to other cases as well.
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arxiv:1411.5834
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in this article a tool for the analysis of population - based eas is used to derive asymptotic upper bounds on the optimization time of the algorithm solving royal roads problem, a test function with plateaus of fitness. in addition to this, limiting distribution of a certain subset of the population is approximated.
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arxiv:1204.2321
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closed classes of three - valued logic generated by periodic symmetric funtions that equal $ 1 $ in tuples from $ \ { 1, 2 \ } ^ n $ and equal $ 0 $ on the rest tuples are considered. criteria for bases existence and finite bases existence for these classes is obtained.
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arxiv:1604.04344
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high energy physics experiments including those at the tevatron and the upcoming lhc require analysis of large data sets which are best handled by distributed computation. we present the design and development of a distributed data analysis framework based on java. analysis jobs run through three phases : discovery of data sets available, brokering / assignment of data sets to analysis servers, and job execution. each phase is represented by a set of abstract interfaces. these interfaces allow different techniques to be used without modification to the framework. for example, the communications interface has been implemented by both a packet protocol and a soap - based scheme. user authentication can be provided either through simple passwords or through a gsi certificates system. data from cms hcal testbeams, the l3 lep experiment, and a hypothetical high - energy linear collider experiment have been interfaced with the framework.
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arxiv:cs/0306055
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we compare the predictions of the fundamentally motivated minimal coupling ( $ \ hat { \ boldsymbol { p } } \ cdot \ hat { \ boldsymbol { a } } $ ) and the ubiquitous dipole coupling ( $ \ hat { \ boldsymbol { x } } \ cdot \ hat { \ boldsymbol { e } } $ ) in the light - matter interaction. by studying the light - matter interaction for hydrogen - like atoms we find that the dipole approximation cannot be a - priori justified to analyze the physics of vacuum excitations ( a very important phenomenon in relativistic quantum information ) since a dominant wavelength is absent in those problems, no matter how small ( as compared to any frequency scale ) the atom is. remarkably, we show that the dipole approximation in those regimes can still be valid as long as the interaction time is longer than the light - crossing time of the atoms, which is a very reasonable assumption. we also highlight some of the subtleties that one has to be careful with when working with the explicitly non - gauge invariant nature of the minimal coupling and we compare it with the explicitly gauge invariant dipole coupling.
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arxiv:1807.08001
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few compounds feature ice - shaping properties. the only compound reported to have ice - shaping properties similar to that of ice - shaping proteins, encountered in many organisms living at low temperature, is zirconium acetate. when a zirconium acetate solution is frozen, oriented and perfectly hexagonal ice crystals can be formed and their growth follows the temperature gradient. to shed light on the water / ice phase transition while freezing zirconium acetate solution we carried out differential scanning calorimetry measurements. from our results, we estimate how many water molecules do not freeze because of their interaction with zr cations. we estimate the colligative properties of the zr concentration on the apparent critical temperature. we further show the phase transition is unaffected by the nature of the base which is used to adjust the ph. our results provide thus new hints on the ice - shaping mechanism of zirconium acetate.
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arxiv:1612.02934
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we propose a cft description for a closed one - dimensional fully frustrated ladder of quantum josephson junctions with mobius boundary conditions ( see cond - mat / 0503555 ; we show how such a system can develop topological order thanks to flux fractionalization. such a property is crucial for its implementation as a " protected " solid state qubit.
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arxiv:hep-th/0507238
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expressivity - - the use of multiple modalities to convey internal state and intent of a robot - - is critical for interaction. yet, due to cost, safety, and other constraints, many robots lack high degrees of physical expressivity. this paper explores using mixed reality to enhance a robot with limited expressivity by adding virtual arms that extend the robot ' s expressiveness. the arms, capable of a range of non - physically - constrained gestures, were evaluated in a between - subject study ( $ n = 34 $ ) where participants engaged in a mixed reality mathematics task with a socially assistive robot. the study results indicate that the virtual arms added a higher degree of perceived emotion, helpfulness, and physical presence to the robot. users who reported a higher perceived physical presence also found the robot to have a higher degree of social presence, ease of use, usefulness, and had a positive attitude toward using the robot with mixed reality. the results also demonstrate the users ' ability to distinguish the virtual gestures ' valence and intent.
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arxiv:1911.09713
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the mechanisms for generation of long - lived spin coherence in a two - dimensional electron gas ( 2deg ) have been studied experimentally by means of a picosecond pump - probe kerr rotation technique. cdte / ( cd, mg ) te quantum wells with a diluted 2deg were investigated. the strong coulomb interaction between electrons and holes, which results in large binding energies of neutral excitons and negatively charged excitons ( trions ), allows one to address selectively the exciton or trion states by resonant optical excitation. different scenarios of spin coherence generation were analyzed theoretically, among them the direct trion photocreation, the formation of trions from photogenerated excitons and the electron - exciton exchange scattering. good agreement between experiment and theory is found.
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arxiv:0707.4294
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integrating large language models ( llms ) with existing knowledge graph ( kg ) databases presents a promising avenue for enhancing llms ' efficacy and mitigating their " hallucinations ". given that most kgs reside in graph databases accessible solely through specialized query languages ( e. g., cypher ), it is critical to connect llms with kg databases by automating the translation of natural language into cypher queries ( termed as " text2cypher " task ). prior efforts tried to bolster llms ' proficiency in cypher generation through supervised fine - tuning ( sft ). however, these explorations are hindered by the lack of annotated datasets of query - cypher pairs, resulting from the labor - intensive and domain - specific nature of such annotation. in this study, we propose synthet2c, a methodology for constructing a synthetic query - cypher pair dataset, comprising two distinct pipelines : ( 1 ) llm - based prompting and ( 2 ) template - filling. synthet2c is applied to two medical kg databases, culminating in the creation of a synthetic dataset, medt2c. comprehensive experiments demonstrate that the medt2c dataset effectively enhances the performance of backbone llms on text2cypher task via sft. both the synthet2c codebase and the medt2c dataset are released in https : / / github. com / zgchung / synthet2c.
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arxiv:2406.10710
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in this paper, we investigate some properties on harmonic functions and solutions to poisson equations. first, we will discuss the lipschitz type spaces on harmonic functions. secondly, we establish the schwarz - pick lemma for harmonic functions in the unit ball $ \ ib ^ n $ of $ \ ir ^ n $, and then we apply it to obtain a bloch theorem for harmonic functions in hardy spaces. at last, we use a normal family argument to extend the landau - bloch type theorem to functions which are solutions to poisson equations.
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arxiv:1407.7179
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we propose prism, a novel framework designed to overcome the limitations of 2d - based preference - based reinforcement learning ( pbrl ) by unifying 3d point cloud modeling and future - aware preference refinement. at its core, prism adopts a 3d point cloud - language model ( 3d - pc - llm ) to mitigate occlusion and viewpoint biases, ensuring more stable and spatially consistent preference signals. additionally, prism leverages chain - of - thought ( cot ) reasoning to incorporate long - horizon considerations, thereby preventing the short - sighted feedback often seen in static preference comparisons. in contrast to conventional pbrl techniques, this integration of 3d perception and future - oriented reasoning leads to significant gains in preference agreement rates, faster policy convergence, and robust generalization across unseen robotic environments. our empirical results, spanning tasks such as robotic manipulation and autonomous navigation, highlight prism ' s potential for real - world applications where precise spatial understanding and reliable long - term decision - making are critical. by bridging 3d geometric awareness with cot - driven preference modeling, prism establishes a comprehensive foundation for scalable, human - aligned reinforcement learning.
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arxiv:2503.10177
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within a recently developed mode - coupling theory for fluids confined to a slit we elaborate numerical results for the long - time limits of suitably generalized intermediate scattering functions. the theory requires as input the density profile perpendicular to the plates, which we obtain from density functional theory within the fundamental - measure framework, as well as symmetry - adapted static structure factors which can be calculated relying on the inhomogeneous percus - yevick closure. our calculations for the nonergodicity parameters for both the collective as well as for the self motion are in qualitative agreement with our extensive event - driven molecular dynamics simulations for the intermediate scattering functions for slightly polydisperse hard - sphere systems at high packing fraction. we show that the variation of the nonergodicity parameters as a function of the wavenumber correlates with the in - plane static structure factors, while subtle effects become apparent in the structure factors and relaxation times of higher mode - indices. a criterion to predict the multiple reentrant from the variation of the in - plane static structure is presented.
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arxiv:2110.14722
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we deduce decompositions of natural representations of general linear groups and symmetric groups from combinatorial bijections involving tableaux. these include some of howe ' s dualities, gelfand models, the schur - weyl decomposition of tensor space, and multiplicity - free decompositions indexed by threshold partitions.
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arxiv:1808.08679
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. the dividing lines between the various types of plastics is not based on material but rather on their properties and applications. for example, polyethylene ( pe ) is a cheap, low friction polymer commonly used to make disposable bags for shopping and trash, and is considered a commodity plastic, whereas medium - density polyethylene ( mdpe ) is used for underground gas and water pipes, and another variety called ultra - high - molecular - weight polyethylene ( uhmwpe ) is an engineering plastic which is used extensively as the glide rails for industrial equipment and the low - friction socket in implanted hip joints. = = = metal alloys = = = the alloys of iron ( steel, stainless steel, cast iron, tool steel, alloy steels ) make up the largest proportion of metals today both by quantity and commercial value. iron alloyed with various proportions of carbon gives low, mid and high carbon steels. an iron - carbon alloy is only considered steel if the carbon level is between 0. 01 % and 2. 00 % by weight. for steels, the hardness and tensile strength of the steel is related to the amount of carbon present, with increasing carbon levels also leading to lower ductility and toughness. heat treatment processes such as quenching and tempering can significantly change these properties, however. in contrast, certain metal alloys exhibit unique properties where their size and density remain unchanged across a range of temperatures. cast iron is defined as an iron – carbon alloy with more than 2. 00 %, but less than 6. 67 % carbon. stainless steel is defined as a regular steel alloy with greater than 10 % by weight alloying content of chromium. nickel and molybdenum are typically also added in stainless steels. other significant metallic alloys are those of aluminium, titanium, copper and magnesium. copper alloys have been known for a long time ( since the bronze age ), while the alloys of the other three metals have been relatively recently developed. due to the chemical reactivity of these metals, the electrolytic extraction processes required were only developed relatively recently. the alloys of aluminium, titanium and magnesium are also known and valued for their high strength to weight ratios and, in the case of magnesium, their ability to provide electromagnetic shielding. these materials are ideal for situations where high strength to weight ratios are more important than bulk cost, such as in the aerospace industry and certain automotive engineering applications. = = = semiconductors = = = a semiconductor is a material that has a
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https://en.wikipedia.org/wiki/Materials_science
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asteroid sizes can be directly measured by observing occultations of stars by asteroids. when there are enough observations across the path of the shadow, the asteroid ' s projected silhouette can be reconstructed. asteroid shape models derived from photometry by the lightcurve inversion method enable us to predict the orientation of an asteroid for the time of occultation. by scaling the shape model to fit the occultation chords, we can determine the asteroid size with a relative accuracy of typically ~ 10 %. we combine shape and spin state models of 44 asteroids ( 14 of them are new or updated models ) with the available occultation data to derive asteroid effective diameters. in many cases, occultations allow us to reject one of two possible pole solutions that were derived from photometry. we show that by combining results obtained from lightcurve inversion with occultation timings, we can obtain unique physical models of asteroids.
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arxiv:1104.4227
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nuclear star clusters that surround supermassive black holes ( smbhs ) in galactic nuclei are among the densest systems in the universe, harbouring millions of stars and compact objects ( cos ). within a few parsecs from the smbh, stars can form binaries. in this paper, we model the supernova ( sn ) process of massive binaries that are born in proximity of the smbh and that produce co binaries. these binaries can later merge via emission of gravitational waves as a consequence of the lidov - kozai mechanism. we study the dynamical evolution of these systems by means of high - precision $ n $ - body simulations, including post - newtonian ( pn ) terms up to 2. 5pn order. we adopt different prescriptions for the natal velocity kicks imparted during the sn processes and find that larger kicks lead to more compact binaries that merge closer to the smbh. we also conclude that most of the mergers enter the ligo band with very high eccentricities. finally, we compute a merger rate of $ 0. 05 $ - - $ 0. 07 \ \ mathrm { gpc } ^ { - 3 } \ mathrm { yr } ^ { - 1 } $, $ 0. 04 $ - - $ 2 \ times 10 ^ { - 3 } \ \ mathrm { gpc } ^ { - 3 } \ mathrm { yr } ^ { - 1 } $, $ 9. 6 \ times 10 ^ { - 6 } $ - - $ 2. 7 \ times 10 ^ { - 3 } \ \ mathrm { gpc } ^ { - 3 } \ mathrm { yr } ^ { - 1 } $ for bh - bh, bh - ns, ns - ns, respectively, smaller than the actual ligo - virgo observed rate.
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arxiv:1907.08008
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of cultivated plants. he devoted his life to the study and improvement of wheat, corn, and other cereal crops that sustain the global population. j. craig venter ( 1946 – ) : american biologist and entrepreneur, one of the first researchers to sequence the human genome, and in 2010 the first to create a cell with a synthetic genome. vladimir vernadsky ( 1863 – 1945 ) : russian and soviet mineralogist and geochemist who is considered one of the founders of geochemistry, biogeochemistry, and of radiogeology. his ideas of noosphere were an important contribution to russian cosmism. carl vogt ( 1817 – 1895 ) : german scientist, philosopher and politician who emigrated to switzerland. vogt published a number of notable works on zoology, geology and physiology. = = w = = w. grey walter ( 1910 – 1977 ) : american neurophysiologist famous for his work on brain waves, and robotician. james d. watson ( 1928 – ) : molecular biologist, physiologist, zoologist, geneticist, nobel - laureate, and co - discover of the structure of dna. john b. watson ( 1878 – 1958 ) : american psychologist who established the psychological school of behaviorism. steven weinberg ( 1933 – 2021 ) : american theoretical physicist. he won the nobel prize in physics in 1979 for the unification of electromagnetism and the weak force into the electroweak force. victor weisskopf ( 1908 – 2002 ) : austrian - american theoretical physicist, co - founder and board member of the union of concerned scientists. frank whittle ( 1907 – 1996 ) : english aerospace engineer, inventor, aviator and royal air force officer. he is credited with independently inventing the turbojet engine ( some years earlier than germany ' s dr. hans von ohain ) and is regarded by many as the father of jet propulsion. eugene wigner ( 1902 – 1995 ) : hungarian - american theoretical physicist, engineer and mathematician. he received half of the nobel prize in physics in 1963 " for his contributions to the theory of the atomic nucleus and the elementary particles, particularly through the discovery and application of fundamental symmetry principles ". arnold wolfendale ( 1927 – 2020 ) : british astronomer who served as astronomer royal from 1991 to 1995, and was emeritus professor in the department of physics at durham university. lewis wolpert cbe frs british frsl ( 1929 – 2021 ) : developmental biologist, author, and broadcaster. steve wozniak ( 1950 – ) : co - founder
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https://en.wikipedia.org/wiki/List_of_atheists_in_science_and_technology
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hierarchical c @ mos2 @ c hollow spheres with the active mos2 nanosheets being sandwiched by carbon layers have been produced by means of a modified template method. the process applies polydopamine ( pda ) layers which inhibit morphology change of the template thereby enforcing the hollow microsphere structure. in addition, pda forms complexes with the mo precursor, leading to an in - situ growth of mos2 on its surface and preventing the nanosheets from agglomeration. it also supplies the carbon that finally sandwiches the 100 - 150 nm thin mos2 spheres. the resulting hierarchically structured material provides a stable microstructure where carbon layers strongly linked to mos2 offer efficient pathways for electron and ion transfer, and concomitantly buffer the volume changes inevitably appearing during the charge - discharge process. carbon - sandwiched mos2 - based electrodes exhibit high specific capacity of approximately 900 ma h g - 1 after 50 cycles at 0. 1 c, excellent cycling stability up to 200 cycles, and superior rate performance. the versatile synthesis method reported here offers a general route to design hollow sandwich structures with a variety of different active materials.
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arxiv:1701.05887
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the validity of the ces approximation is investigated by comparison with direct diagonalisation of a model vibronic hamiltonian of $ n $ identical monomers interacting electronically. even for quite short aggregates ( n \ gtrsim 6 ) the ces approximation is shown to give results in agreement with direct diagonalisation, for all coupling strengths, except that of intermediate positive coupling ( the h - band region ). however, previously excellent agreement of ces calculations and measured spectra in the h - band region was obtained [ a. eisfeld, j. s. briggs, chem. phys. 324, 376 ]. this is shown to arise from use of the measured monomer spectrum which includes implicitly dissipative effects not present in the model calculation.
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arxiv:1008.3623
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we study the transport through evanescent waves in graphene quantum dots of different geometries. the transmission is suppressed when the leads are attached to edges of the same majority sublattice. otherwise, the transmission depends exponentially on the distance between leads in rectangular dots, and as a power law in circular dots. the transmission through junctions where the transmitted and reflected currents belong to the opposite valley as the incoming one depends on details of the lattice structure at distances comparable to the atomic spacing.
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arxiv:0804.2348
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we have identified a sample of 10 highly reliable off - nuclear ( > 2 kpc ) x - ray sources at z = 0. 03 - 0. 25 in late - type host galaxies within the two goods fields ( i. e., the two chandra deep fields ). the combination of the superb spatial resolution and great depth of the hst acs and chandra acis coverage in the goods fields is critical to the identification of these sources. we extend the study of this enigmatic population up to higher redshifts and larger look - back times than has been possible before, finding that the fraction of optically luminous galaxies exhibiting luminous off - nuclear sources at z ~ 0. 1 is larger than at the current time ( ~ 36 % versus ~ 8 % ). the x - ray luminosities of the goods off - nuclear x - ray sources are comparable to or slightly greater than the integrated point - source x - ray luminosities of nearby galaxies, providing a possible constraint on the x - ray luminosity function at higher star - formation rates. x - ray variability demonstrates that several of these sources are likely single accreting black holes ; for the majority, however, the number of x - ray counts is too low for x - ray variability studies.
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arxiv:astro-ph/0308408
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we start from a hamiltonian describing non - interacting fermions and add bosons to the model, with a jaynes - cummings - like interaction between the bosons and fermions. because of the specific form of the interaction the model can be solved exactly. in the ground state, part of the electrons form bound pairs with opposite momentum and spin. the model also shows a gap in the kinetic energy of the fermions, but not in the spectrum of the full hamiltonian. this gap is not of a mean - field nature, but is due to the pauli exclusion principle.
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arxiv:1002.1817
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the paper considers an investment timing problem appearing in real options theory. present values from an investment project are modeled by general diffusion process. we prove necessary and sufficient conditions under which an optimal investment time is induced by threshold strategy. we study also the conditions of optimality of threshold strategy ( over all threshold strategies ) and discuss the connection between solutions to investment timing problem and to free - boundary problem.
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arxiv:1511.00468
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emerging compute express link ( cxl ) enables cost - efficient memory expansion beyond the local dram of processors. while its cxl $. $ mem protocol provides minimal latency overhead through an optimized protocol stack, frequent cxl memory accesses can result in significant slowdowns for memory - bound applications whether they are latency - sensitive or bandwidth - intensive. the near - data processing ( ndp ) in the cxl controller promises to overcome such limitations of passive cxl memory. however, prior work on ndp in cxl memory proposes application - specific units that are not suitable for practical cxl memory - based systems that should support various applications. on the other hand, existing cpu or gpu cores are not cost - effective for ndp because they are not optimized for memory - bound applications. in addition, the communication between the host processor and cxl controller for ndp offloading should achieve low latency, but existing cxl $. $ io / pcie - based mechanisms incur $ \ mu $ s - scale latency and are not suitable for fine - grained ndp. to achieve high - performance ndp end - to - end, we propose a low - overhead general - purpose ndp architecture for cxl memory referred to as memory - mapped ndp ( m $ ^ 2 $ ndp ), which comprises memory - mapped functions ( m $ ^ 2 $ func ) and memory - mapped $ \ mu $ threading ( m $ ^ 2 \ mu $ thread ). m $ ^ 2 $ func is a cxl $. $ mem - compatible low - overhead communication mechanism between the host processor and ndp controller in cxl memory. m $ ^ 2 \ mu $ thread enables low - cost, general - purpose ndp unit design by introducing lightweight $ \ mu $ threads that support highly concurrent execution of kernels with minimal resource wastage. combining them, m $ ^ 2 $ ndp achieves significant speedups for various workloads by up to 128x ( 14. 5x overall ) and reduces energy by up to 87. 9 % ( 80. 3 % overall ) compared to baseline cpu / gpu hosts with passive cxl memory.
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arxiv:2404.19381
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the classical theory of rubber elasticity fails in the regime of large deformation. the un - derlying physical mechanism has been under debate for long time. in this work, we test the recently proposed mechanism of thermal elastic fluctuations by xing, goldbart and radzi - hovsky1 against the biaxial stress - strain data of three distinct polymer networks with very different network structures, synthesized by urayama2 and kawabata3 respectively. we find that both the two parameters version and the one - parameter version of the xgr theory provide satisfactory description of the elasticity in whole deformation range. for comparison, we also fit the same sets of data using the slip - link model by edwards and vilgis with four parameters. the fitting qualities of two theories are found to be comparable.
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arxiv:1007.4274
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this article begins with a brief review of random matrix theory, followed by a discussion of how the large - $ n $ limit of random matrix models can be realized using operator algebras. i then explain the notion of " brown measure, " which play the role of the eigenvalue distribution for operators in an operator algebra. i then show how methods of partial differential equations can be used to compute brown measures. i consider in detail the case of the circular law and then discuss more briefly the case of the free multiplicative brownian motion, which was worked out recently by the author with driver and kemp.
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arxiv:1910.09274
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enhancing simulation environments to replicate real - world driver behavior is essential for developing autonomous vehicle technology. while some previous works have studied the yielding reaction of lag vehicles in response to a merging car at highway on - ramps, the possible lane - change reaction of the lag car has not been widely studied. in this work we aim to improve the simulation of the highway merge scenario by including the lane - change reaction in addition to yielding behavior of main - lane lag vehicles, and we evaluate two different models for their ability to capture this reactive lane - change behavior. to tune the payoff functions of these models, a novel naturalistic dataset was collected on u. s. highways that provided several hours of merge - specific data to learn the lane change behavior of u. s. drivers. to make sure that we are collecting a representative set of different u. s. highway geometries in our data, we surveyed 50, 000 u. s. highway on - ramps and then selected eight representative sites. the data were collected using roadside - mounted lidar sensors to capture various merge driver interactions. the models were demonstrated to be configurable for both keep - straight and lane - change behavior. the models were finally integrated into a high - fidelity simulation environment and confirmed to have adequate computation time efficiency for use in large - scale simulations to support autonomous vehicle development.
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arxiv:2404.09851
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for a number of useful quantum circuits, qudit constructions have been found which reduce resource requirements compared to the best known or best possible qubit construction. however, many of the necessary qutrit gates in these constructions have never been explicitly and efficiently constructed in a fault - tolerant manner. we show how to exactly and unitarily construct any qutrit multiple - controlled clifford + t unitary using just clifford + t gates and without using ancillae. the t - count to do so is polynomial in the number of controls $ k $, scaling as $ o ( k ^ { 3. 585 } ) $. with our results we can construct ancilla - free clifford + t implementations of multiple - controlled t gates as well as all versions of the qutrit multiple - controlled toffoli, while the analogous results for qubits are impossible. as an application of our results, we provide a procedure to implement any ternary classical reversible function on $ n $ trits as an ancilla - free qutrit unitary using $ o ( 3 ^ n n ^ { 3. 585 } ) $ t gates.
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arxiv:2204.00552
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we present a first search for dark - trident scattering in a neutrino beam using a data set corresponding to $ 7. 2 \ times 10 ^ { 20 } $ protons on target taken with the microboone detector at fermilab. proton interactions in the neutrino target at the main injector produce $ \ pi ^ 0 $ and $ \ eta $ mesons, which could decay into dark - matter ( dm ) particles mediated via a dark photon $ a ^ \ prime $. a convolutional neural network is trained to identify interactions of the dm particles in the liquid - argon time projection chamber ( lartpc ) exploiting its image - like reconstruction capability. in the absence of a dm signal, we provide limits at the $ 90 \ % $ confidence level on the squared kinematic mixing parameter $ \ varepsilon ^ 2 $ as a function of the dark - photon mass in the range $ 10 \ le m _ { a ^ \ prime } \ le 400 $ mev. the limits cover previously unconstrained parameter space for the production of fermion or scalar dm particles $ \ chi $ for two benchmark models with mass ratios $ m _ { \ chi } / m _ { a ^ \ prime } = 0. 6 $ and $ 2 $ and for dark fine - structure constants $ 0. 1 \ le \ alpha _ d \ le 1 $.
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arxiv:2312.13945
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the most recent and promising strategies for mitigating methane emissions in ruminants are reviewed highlighting the potential of reductive acetogenesis as a viable alternative to methanogenesis. the emergence of clustered regularly interspaced short palindromic repeats ( crispr ) technology, and its exceptional precision in genome editing, further enhances the prospects of exploring this avenue. indeed, research in ruminant methane mitigation has been extensive, and over the years has resulted in the development of a wide variety of mitigation strategies. there is no doubt that the concepts of meat alternatives like lab - meat, microbial proteins and plant proteins may produce equivalent emissions. reducing methane intensity through breeding and diet has been limited by our inability to phenotype ruminants in a high - throughput manner and the intensification of feed - food competition. although chemical inhibitors have demonstrated effectiveness in manipulating the rumen microbiota to reduce net emissions, their success is constrained in terms of duration and feasibility in grazing system. progress in making acetogenesis the dominant hydrogen sink in the rumen has been hampered by the thermodynamic cost of the reaction and the limited hydrogen levels in the rumen environment. we believe that crispr may allow the dominance of acetogenesis by converting methanogens into acetogens. we propose methanobrevibacter ruminantium to be targeted because it is the dominant methane producer in the rumen.
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arxiv:2307.14372
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in this paper we describe the hopf algebras on planar binary trees used to renormalize the feynman propagators of quantum electrodynamics, and the coaction which describes the renormalization procedure. both structures are related to some semi - direct coproduct of hopf algebras.
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arxiv:math/0112043
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in computational relativity, critical behaviour near the black hole threshold has been studied numerically for several models in the last decade. in this paper we present a spatial galerkin method, suitable for finding numerical solutions of the einstein - dirac equations in spherically symmetric spacetime ( in polar / areal coordinates ). the method features exact conservation of the total electric charge and allows for a spatial mesh adaption based on physical arclength. numerical experiments confirm excellent robustness and convergence properties of our approach. hence, this new algorithm is well suited for studying critical behaviour.
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arxiv:gr-qc/0607128
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we investigate, for the first time, a scenario where the dark matter consists of three complex scalar fields that are stabilized by a single $ z _ 7 $ symmetry. as an extension of the well - known scalar higgs - portal, this $ z _ 7 $ model is also subject to important restrictions arising from the relic density constraint and from direct detection experiments. our goal in this paper is to find and characterize the viable regions of this model, and to analyze its detection prospects in future experiments. first, the processes that affect the relic densities are identified ( they include semiannihilations and conversions ) and then incorporated into the boltzmann equations for the dark matter abundances, which are numerically solved with micromegas. by means of random scans of the parameter space, the regions consistent with current data, including the recent direct detection limit from the lz experiment, are selected. our results reveal that the $ z _ 7 $ model is indeed viable over a wide range of dark matter masses and that both conversions and semiannihilations play an important role in determining the relic densities. remarkably, we find that in many cases all three of the dark matter particles give rise to observable signals in future direct detection experiments, providing a suitable way to test this scenario.
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arxiv:2212.07488
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magnetic reconnection is a sporadic process responsible for energy release in space and laboratory plasmas. it is believed that the tearing mode instability may be responsible for the onset of reconnection in the magnetotail. however, due to its elusive nature, there is an absence of in - situ observations of the tearing instability prior to magnetic reconnection in our nearest natural plasma laboratory. using neural network outlier detection methods in conjunction with cluster spacecraft data, we find unique electron pitch angle distributions that are consistent with simulation predictions of the tearing instability and the subsequent evolution of plasma electrons and reconnection. we confirm that the events identified via our neural network outlier method are well above the tearing stability threshold based on the criterion detailed in this paper. we find signatures of magnetic reconnection minutes after the majority of tearing observations. our analysis of the tearing instability provides new insights into the fundamental understanding of the mechanism responsible for reconnection, a process that is ubiquitous in different astrophysical plasma regimes across the universe and in laboratory experiments on earth.
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arxiv:2202.12389
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it is shown that rational dilation fails on broad collection of distinguished varieties associated to constrained subalgebras of the disk algebra of the form c + b a ( d ), where b is a finite blaschke product with two or more zeros. this is accomplished in part by finding a minimal set of test functions. in addition, an agler - pick interpolation theorem is given and it is proved that there exist kaijser - varopoulos style examples of non - contractive unital representations where the generators are contractions.
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arxiv:1711.11090
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community based question answering services have arisen as a popular knowledge sharing pattern for netizens. with abundant interactions among users, individuals are capable of obtaining satisfactory information. however, it is not effective for users to attain answers within minutes. users have to check the progress over time until the satisfying answers submitted. we address this problem as a user personalized satisfaction prediction task. existing methods usually exploit manual feature selection. it is not desirable as it requires careful design and is labor intensive. in this paper, we settle this issue by developing a new multiple instance deep learning framework. specifically, in our settings, each question follows a weakly supervised learning multiple instance learning assumption, where its obtained answers can be regarded as instance sets and we define the question resolved with at least one satisfactory answer. we thus design an efficient framework exploiting multiple instance learning property with deep learning to model the question answer pairs. extensive experiments on large scale datasets from stack exchange demonstrate the feasibility of our proposed framework in predicting askers personalized satisfaction. our framework can be extended to numerous applications such as ui satisfaction prediction, multi armed bandit problem, expert finding and so on.
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arxiv:1611.08096
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chip from melting when operating at higher speeds. advances in speed may be possible in the future by virtue of more power - efficient cpu designs and multi - cell processors. theodore modis holds the singularity cannot happen. he claims the " technological singularity " and especially kurzweil lack scientific rigor ; kurzweil is alleged to mistake the logistic function ( s - function ) for an exponential function, and to see a " knee " in an exponential function where there can in fact be no such thing. in a 2021 article, modis pointed out that no milestones – breaks in historical perspective comparable in importance to the internet, dna, the transistor, or nuclear energy – had been observed in the previous twenty years while five of them would have been expected according to the exponential trend advocated by the proponents of the technological singularity. ai researcher jurgen schmidhuber stated that the frequency of subjectively " notable events " appears to be approaching a 21st - century singularity, but cautioned readers to take such plots of subjective events with a grain of salt : perhaps differences in memory of recent and distant events could create an illusion of accelerating change where none exists. microsoft co - founder paul allen argued the opposite of accelerating returns, the complexity brake : the more progress science makes towards understanding intelligence, the more difficult it becomes to make additional progress. a study of the number of patents shows that human creativity does not show accelerating returns, but in fact, as suggested by joseph tainter in his the collapse of complex societies, a law of diminishing returns. the number of patents per thousand peaked in the period from 1850 to 1900, and has been declining since. the growth of complexity eventually becomes self - limiting, and leads to a widespread " general systems collapse ". hofstadter ( 2006 ) raises concern that ray kurzweil is not sufficiently scientifically rigorous, that an exponential tendency of technology is not a scientific law like one of physics, and that exponential curves have no " knees ". nonetheless, he did not rule out the singularity in principle in the distant future and in the light of chatgpt and other recent advancements has revised his opinion significantly towards dramatic technological change in the near future. jaron lanier denies that the singularity is inevitable : " i do not think the technology is creating itself. it ' s not an autonomous process. " furthermore : " the reason to believe in human agency over technological determinism is that you can then have an economy where people earn their own way
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https://en.wikipedia.org/wiki/Technological_singularity
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this brief introduction to model predictive control specifically addresses stochastic model predictive control, where probabilistic constraints are considered. a simple linear system subject to uncertainty serves as an example. the matlab code for this stochastic model predictive control example is available online.
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arxiv:2101.12020
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first principle computer simulations yield evidence of a finite superfluid response at low temperature of a parahydrogen cluster of 15 molecules in bulk superfluid he - 4. the superfluid fraction is worth ~ 44 % at t = 0. 25 k, growing to about 66 % at t = 0. 15 k, i. e., it is substantially reduced compared to that of the same cluster in vacuo, due to higher molecular localization. the implications of these findings on the interpretation of experiments with linear molecules embedded in parahydrogen clusters immersed in superfluid helium are discussed.
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arxiv:1912.11327
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this is the sequel to " asymptotically locally euclidean metrics with holonomy su ( m ) ", math. ag / 9905041. let g be a subgroup of u ( m ), and x a resolution of c ^ m / g. we define a special class of kahler metrics g on x called quasi asymptotically locally euclidean ( qale ) metrics. these satisfy a complicated asymptotic condition, implying that g is asymptotic to the euclidean metric on c ^ m / g away from its singular set. when c ^ m / g has an isolated singularity, qale metrics are just ale metrics. our main interest is in ricci - flat qale kahler metrics on x. we prove an existence result for ricci - flat qale kahler metrics : if g is a subgroup of su ( m ) and x a crepant resolution of c ^ m / g, then there is a unique ricci - flat qale kahler metric on x in each kahler class. this is proved using a version of the calabi conjecture for qale manifolds. we also determine the holonomy group of the metrics in terms of g. these results will be applied in the author ' s book ( " compact manifolds with special holonomy ", to be published by oup, 2000 ) to construct new examples of compact 7 - and 8 - manifolds with exceptional holonomy. they can also be used to describe the calabi - yau metrics on resolutions of a calabi - yau orbifold.
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arxiv:math/9905043
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we study the problem of user segmentation : given a set of users and one or more predefined groups or segments, assign users to their corresponding segments. as an example, for a segment indicating particular interest in a certain area of sports or entertainment, the task will be to predict whether each single user will belong to the segment. however, there may exist numerous long tail prediction tasks that suffer from data availability and may be of heterogeneous nature, which make it hard to capture using single off the shelf model architectures. in this work, we present supercone, our unified predicative segments system that addresses the above challenges. it builds on top of a flat concept representation that summarizes each user ' s heterogeneous digital footprints, and uniformly models each of the prediction task using an approach called " super learning ", that is, combining prediction models with diverse architectures or learning method that are not compatible with each other. following this, we provide an end to end approach that learns to flexibly attend to best suited heterogeneous experts adaptively, while at the same time incorporating deep representations of the input concepts that augments the above experts. experiments show that supercone significantly outperform state - of - the - art recommendation and ranking algorithms on a wide range of predicative segment tasks and public structured data learning benchmarks.
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arxiv:2203.07029
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this is the submission for mitosis detection in the context of the midog 2021 challenge. it is based on the two - stage objection model faster rcnn as well as densenet as a backbone for the neural network architecture. it achieves a f1 - score of 0. 6645 on the preliminary test phase leaderboard.
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arxiv:2109.00816
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the paper proposes resource allocation ( ra ) schemes for a closed loop feedback control system by analysing the control - communication dependencies. we consider an automated guided vehicle ( agv ) that communicates with a controller located in an edge - cloud over a wireless fading channel. the control commands are transmitted to an agv and the position state is feedback to the controller at every time - instant. a control stability based scheduling metric ' probability of instability ' is evaluated for the resource allocation. the performance of stability based ra scheme is compared with the maximum snr based ra scheme and control error first approach in an overloaded and non - overloaded scenario. the ra scheme with the stability constraints significantly reduces the resource utilization and is able to schedule more number of agvs while maintaining its stability. moreover, the proposed ra scheme is independent of control state and depends upon consecutive packet errors, the control parameters like sampling time and agv velocity. furthermore, we also analyse the impact of ra schemes on the agv ' s stability and error performance, and evaluated the number of unstable agvs.
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arxiv:2301.09388
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one of the answers to the measurement problem in quantum theory is given by the copenhagen - interpretation of quantum theory ( i. e. orthodox quantum theory ) in which the wave function collapse happens in ( by ) the mind of observer. in fact, at first, great scientists like von neumann, london, bauer and wigner ( initially ) believed that the wave function collapse occurs in the brain or is caused by the consciousness of observer. however, this issue has been stayed yet very controversial. in fact, there are many challenging discussions about the survival of quantum effects in microscopic structures of the human brain, which is mainly because of quick decoherence of quantum states due to hot, wet and noisy environment of the brain that forbids long life coherence for brain processing. nevertheless, there are also several arguments and evidences that emergence of large coherent states is feasible in the brain. in this paper, our approach is based on the latter in which macroscopic quantum states are probable in the human brain. here, we simulate the delayed luminescence of photons in neurons with a brassard - like teleportation circuit, i. e. equivalent to the transfer of quantum states of photons through the visual pathways from retina to the visual cortex. indeed, our simulation considers both classical and quantum mechanical aspects of processing in neurons. as a result and based on our simulation, it is possible for our brain to receive the exact quantum states of photons in the visual cortex to be collapsed by our consciousness, which supports the copenhagen - interpretation of measurement problem in quantum theory.
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arxiv:1412.7551
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we report muon spin rotation measurements of the local magnetic susceptibility around a positive muon in the paramagnetic state of the quasi one - dimensional spin 1 / 2 antiferromagnet dichlorobis ( pyridine ) copper ( ii ). signals from three distinct sites are resolved and have a temperature dependent frequency shift which is significantly different than the magnetic susceptibility. this difference is attributed to a muon induced perturbation of the spin 1 / 2 chain. the obtained frequency shifts are compared with transfer matrix dmrg numerical simulations.
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arxiv:cond-mat/0301507
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we study the spectral geometry of the riemann curvature tensor for pseudo - riemannian manifolds and provide some examples illustrating the phenomena which can arise in the higher signature setting. dedication : this paper is dedicated to the memory of our colleague prof. g. tsagas who studied the spectral geometry of laplacian.
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arxiv:math/0312249
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by using the gauge / gravity duality and the maldacena prescription we compute the expectation values of the wilson loops in noncommutative yang - mills ( ncym ) theory in ( 3 + 1 ) dimensions. we consider both the time - like and the light - like wilson loops. the gravity dual background is given by a particular decoupling limit of ( d1, d3 ) bound state of type iib string theory. we obtain the velocity dependent quark - antiquark potential and numerically study how the dipole length and the potential change with velocity ( for 0 < v < 1, i. e., the wilson loop is time - like ) of the dipole as well as noncommutativity. we discuss and compare the results with the known commutative results. we also obtain an analytic expression for the screening length when the rapidity is large and the noncommutativity parameter is small with the product remaining small. when v \ rightarrow 1, the time - like wilson loop becomes light - like and in that case we obtain the form of the jet quenching parameter for the strongly coupled noncommutative yang - mills plasma which matches with our earlier results obtained using different method.
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arxiv:1201.0129
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source code summarization aims to generate natural language summaries from structured code snippets for better understanding code functionalities. however, automatic code summarization is challenging due to the complexity of the source code and the language gap between the source code and natural language summaries. most previous approaches either rely on retrieval - based ( which can take advantage of similar examples seen from the retrieval database, but have low generalization performance ) or generation - based methods ( which have better generalization performance, but cannot take advantage of similar examples ). this paper proposes a novel retrieval - augmented mechanism to combine the benefits of both worlds. furthermore, to mitigate the limitation of graph neural networks ( gnns ) on capturing global graph structure information of source code, we propose a novel attention - based dynamic graph to complement the static graph representation of the source code, and design a hybrid message passing gnn for capturing both the local and global structural information. to evaluate the proposed approach, we release a new challenging benchmark, crawled from diversified large - scale open - source c projects ( total 95k + unique functions in the dataset ). our method achieves the state - of - the - art performance, improving existing methods by 1. 42, 2. 44 and 1. 29 in terms of bleu - 4, rouge - l and meteor.
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arxiv:2006.05405
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in 1935, einstein, podolsky and rosen ( epr ) considered two particles in an entangled state of motion to illustrate why they questioned the completeness of quantum theory. in the past decades, microscopic systems with entanglement in various degrees of freedom have successfully been generated, representing compelling evidence to support the completeness of quantum theory. today, the generation of an epr - entangled state of motion of two massive objects of up to the kilogram - scale seems feasible with state - of - the - art technology. recently, the generation and verification of epr - entangled mirror motion in interferometric gravitational wave detectors was proposed, with the aim of testing quantum theory in the regime of macroscopic objects, and to make available nonclassical probe systems for future tests of modified quantum theories that include ( non - relativistic ) gravity. the work presented here builds on these earlier results and proposes a specific michelson interferometer that includes two high - quality laser mirrors of about 0. 1 kg mass each. the mirrors are individually suspended as pendula and located close to each other, and cooled to about 4 k. the physical concepts for the generation of the epr - entangled centre of mass motion of these two mirrors are described. apart from a test of quantum mechanics in the macroscopic world, the setup is envisioned to test predictions of yet - to - be - elaborated modified quantum theories that include gravitational effects.
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arxiv:1508.06462
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, some argue that we are already in the midst of a major evolutionary transition that merges technology, biology, and society. digital technology has infiltrated the fabric of human society to a degree of indisputable and often life - sustaining dependence. a 2016 article in trends in ecology & evolution argues that " humans already embrace fusions of biology and technology. we spend most of our waking time communicating through digitally mediated channels... we trust artificial intelligence with our lives through antilock braking in cars and autopilots in planes... with one in three courtships leading to marriages in america beginning online, digital algorithms are also taking a role in human pair bonding and reproduction ". the article further argues that from the perspective of the evolution, several previous major transitions in evolution have transformed life through innovations in information storage and replication ( rna, dna, multicellularity, and culture and language ). in the current stage of life ' s evolution, the carbon - based biosphere has generated a system ( humans ) capable of creating technology that will result in a comparable evolutionary transition. the digital information created by humans has reached a similar magnitude to biological information in the biosphere. since the 1980s, the quantity of digital information stored has doubled about every 2. 5 years, reaching about 5 zettabytes in 2014 ( 5×1021 bytes ). in biological terms, there are 7. 2 billion humans on the planet, each having a genome of 6. 2 billion nucleotides. since one byte can encode four nucleotide pairs, the individual genomes of every human on the planet could be encoded by approximately 1×1019 bytes. the digital realm stored 500 times more information than this in 2014 ( see figure ). the total amount of dna contained in all of the cells on earth is estimated to be about 5. 3×1037 base pairs, equivalent to 1. 325×1037 bytes of information. if growth in digital storage continues at its current rate of 30 – 38 % compound annual growth per year, it will rival the total information content contained in all of the dna in all of the cells on earth in about 110 years. this would represent a doubling of the amount of information stored in the biosphere across a total time period of just 150 years ". = = = implications for human society = = = in february 2009, under the auspices of the association for the advancement of artificial intelligence ( aaai ), eric horvitz chaired a meeting of leading computer scientists, artificial intelligence researchers and robotic
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https://en.wikipedia.org/wiki/Technological_singularity
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order - invariant first - order logic is an extension of first - order logic fo where formulae can make use of a linear order on the structures, under the proviso that they are order - invariant, i. e. that their truth value is the same for all linear orders. we continue the study of the two - variable fragment of order - invariant first - order logic initiated by zeume and harwath, and study its complexity and expressive power. we first establish conexptime - completeness for the problem of deciding if a given two - variable formula is order - invariant, which tightens and significantly simplifies the con2exptime proof by zeume and harwath. second, we address the question of whether every property expressible in order - invariant two - variable logic is also expressible in first - order logic without the use of a linear order. we suspect that the answer is ` ` no ' '. to justify our claim, we present a class of finite tree - like structures ( of unbounded degree ) in which a relaxed variant of order - invariant two - variable fo expresses properties that are not definable in plain fo. by contrast, we show that if one restricts their attention to classes of structures of bounded degree, then the expressive power of order - invariant two - variable fo is contained within fo.
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arxiv:2304.08410
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in this paper, we consider the physical layer security ( pls ) problem for integrated sensing and communication ( isac ) systems in the presence of hybrid - colluding eavesdroppers, where an active eavesdropper ( ae ) and a passive eavesdropper ( pe ) collude to intercept the confidential information. to ensure the accuracy of sensing while preventing the eavesdropping, a base station transmits a signal consisting of information symbols and sensing waveform, in which the sensing waveform can be also used as artificial noise to interfere with eavesdroppers. under this setup, we propose an alternating optimization - based two stage scheme ( ao - tss ) for improving the sensing and communication performance. in the first stage, based on the assumptions that the perfect channel state information ( csi ) of the ae and statistical csi of the pe are known, the communication and sensing beamforming problem is formulated with the objective of minimizing the weighted sum of the beampattern matching mean squared error ( mse ) and cross - correlation, subject to the secure transmission constraint. to tackle the non - convexity, we propose a semi - definite relaxation ( sdr ) algorithm and a reduced - complexity zero - forcing ( zf ) algorithm. then, the scenarios are further extended to more general cases with imperfect ae csi and unknown pe csi. to further improve the communication performance, the second - stage problem is developed to optimize the secrecy rate threshold under the radar performance constraint. finally, numerical results demonstrate the superiority of the proposed scheme in terms of sensing and secure communication.
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arxiv:2502.04912
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we investigate spectral properties of the laplacian in $ l ^ 2 ( q ) $, where $ q $ is a tubular region in $ \ mathbb { r } ^ 3 $ of a fixed cross section, and the boundary conditions combined a dirichlet and a neumann part. we analyze two complementary situations, when the tube is bent but not twisted, and secondly, it is twisted but not bent. in the first case we derive sufficient conditions for the presence and absence of the discrete spectrum showing, roughly speaking, that they depend on the direction in which the tube is bent. in the second case we show that a constant twist raises the threshold of the essential spectrum and a local slowndown of it gives rise to isolated eigenvalues. furthermore, we prove that the spectral threshold moves up also under a sufficiently gentle periodic twist.
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arxiv:1708.08068
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we study the dynamics of the fluctuations of the variance $ s $ of the order parameter of the gaussian model, following a temperature quench of the thermal bath. at each time $ t $, there is a critical value $ s _ c ( t ) $ of $ s $ such that fluctuations with $ s > s _ c ( t ) $ are realized by condensed configurations of the systems, i. e., a single degree of freedom contributes macroscopically to $ s $. this phenomenon, which is closely related to the usual condensation occurring on average quantities, is usually referred to as { \ it condensation of fluctuations }. we show that the probability of fluctuations with $ s < \ inf _ t [ s _ c ( t ) ] $, associated to configurations that never condense, after the quench converges rapidly and in an adiabatic way towards the new equilibrium value. the probability of fluctuations with $ s > \ inf _ t [ s _ c ( t ) ] $, instead, displays a slow and more complex behavior, because the macroscopic population of the condensing degree of freedom is involved.
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arxiv:1907.12618
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the energy - dependent scattering of fermions from a localized orbital at an energy - dependent rate $ \ gamma ( \ epsilon ) \ propto | \ epsilon | ^ r $ gives rise to quantum critical points ( qcps ) in the pseudogap single - impurity anderson model separating a local moment phase with an unscreened spin moment from a strong - coupling phase which slightly deviates from the screened phase of standard kondo problem. using the time - dependent numerical renormalization group ( td - nrg ) approach we show that local dynamic properties always equilibrate towards a steady - state value even for quenches across the qcp but with systematic deviations from the thermal equilibrium depending on the distance to the critical coupling. local non - equilibrium properties are presented for interaction quenches and hybridization quenches. we augment our numerical data by an analytical calculation that becomes exact at short times and find excellent agreement between the numerics and the analytical theory. for interaction quenches within the screened phase we find a universal function for the time - dependent local double occupancy. we trace back the discrepancy between our results and the data obtained by a time - dependent gutzwiller variational approach to restrictions of the wave - function ansatz in the gutzwiller theory : while the nrg ground states properly account for the formation of an extended spin moment which decouples from the system in the unscreened phase, the gutzwiller ansatz only allows the formation of the spin moment on the local impurity orbital.
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arxiv:1410.1770
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we successfully demonstrate a quantum gas microscopy using the faraday effect which has an inherently non - destructive nature. the observed faraday rotation angle reaches 3. 0 ( 2 ) degrees for a single atom. we reveal the non - destructive feature of this faraday imaging method by comparing the detuning dependence of the faraday signal strength with that of the photon scattering rate. we determine the atom distribution with deconvolution analysis. we also demonstrate the absorption and the dark field faraday imaging, and reveal the different shapes of the point spread functions for these methods, which are fully explained by theoretical analysis. our result is an important first step towards an ultimate quantum non - demolition site - resolved imaging and furthermore opens up the possibilities for quantum feedback control of a quantum many - body system with a single - site resolution.
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arxiv:1607.07045
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for real $ a > 0 $, let $ x _ a $ denote a random variable with the gamma distribution with parameters $ a $ and $ 1 $. then $ \ mathsf p ( x _ a - a > c ) $ is increasing in $ a $ for each real $ c \ ge0 $ ; non - increasing in $ a $ for each real $ c \ le - 1 / 3 $ ; and non - monotonic in $ a $ for each $ c \ in ( - 1 / 3, 0 ) $. this extends and / or refines certain previously established results.
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arxiv:2012.13578
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the aim of this work is to examine the upper - semicontinuity properties of the family of global attractors admitted by a non - isothermal viscous relaxation of some nonlocal cahn - hilliard equations. we prove that the family of global attractors is upper - semicontinuous as the perturbation parameters vanish. additionally, under suitable assumptions, we prove that the family of global attractors satisfies a further upper - semicontinuity type estimate whereby the difference between trajectories of the relaxation problem and the limit isothermal non - viscous problem is explicitly controlled, in the topology of the relaxation problem, in terms of the relaxation parameters.
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arxiv:1805.06320
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quantum control of an open system is demonstrated employing a thermodynamically consistent master equation. in this framework, the open system dynamics depend on the control protocol due to the dressing of the system by the drive. this interrelation serves as the key element for control. the influence of the external drive is incorporated within the dynamical equation, enabling an indirect control of the dissipation. the control paradigm is displayed by analyzing entropy changing state to state transformations, heating and cooling n - level systems. following, we study the generation of quantum non - unitary maps via coherent control. these include both reset maps with complete memory loss and single - qubit unitary maps under dissipative conditions.
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arxiv:2107.11767
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we investigate the role of domain walls in the ultrafast magnon dynamics of an antiferromagnetic nio single crystal in a pump - probe experiment with variable pump photon energy. analysing the amplitude of the energy - dependent photo - induced ultrafast spin dynamics, we detect a yet unreported coupling between the material ' s characteristic thz - and a ghz - magnon modes. we explain this unexpected coupling between two orthogonal eigenstates of the corresponding hamiltonian by modelling the magneto - elastic interaction between spins in different domains. we find that such interaction, in the non - linear regime, couples the two different magnon modes via the domain walls and it can be optically exploited via the exciton - magnon resonance.
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arxiv:2103.11203
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the vajpayee administration for carrying out the series of nuclear tests, accusing the government of trying to use the tests for political ends rather than to enhance the country ' s national security. by the time india had conducted tests, the country had a total of $ 44bn in loans in 1998, from the imf and the world bank. the industrial sectors of the indian economy were likely to be hurt by sanctions with the foreign companies, which had invested heavily in india, facing consequences of impending sanctions. the indian government announced that it had factored the economic response and was willing to take the consequences. = = = international = = = the united states issued a statement condemning india and threatened economic sanctions. the intelligence community felt humiliated for its failure to detect the preparations for the test. in keeping with its preferred approach to foreign policy in recent decades, and in compliance with the 1994 anti - proliferation law, the united states imposed economic sanctions on india. the sanctions on india consisted of cutting off all assistance to india except humanitarian aid, banning the export of certain defense material and technologies, ending american credit and credit guarantees to india, and requiring the us to oppose lending by international financial institutions to india. the united states held talks with india over the issue of india becoming a part of the ctbt and npt and pressurized to rollback india ' s nuclear program. india did not accede to the request stating that it was not consistent with her national security interest. canada criticized india ' s actions. japan imposed economic sanctions which included freezing all new loans and grants except for humanitarian aid. few other nations also imposed sanctions on india, primarily in the form of suspension of foreign aid and government - to - government credit lines. china stated that it was seriously concerned about the tests which are not favorable to the peace and stability in the region and called for the international community to pressure india to cease the development of nuclear weapons. it further rejected claims of india ' s stated rationale of needing nuclear capabilities to counter a chinese threat as unfounded. however, permanent members of the united nations security council such as the united kingdom, france, and russia refrained from making any statements condemning the tests. pakistan issued a statement blaming india for instigating a nuclear arms race in the region with prime minister nawaz sharif stating that his country will take appropriate action. pakistan carried out six nuclear tests under the codename chagai - i on 28 may 1998 and chagai - ii on 30 may 1998. pakistan ' s leading nuclear physicist, pervez hoodbhoy,
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https://en.wikipedia.org/wiki/Pokhran-II
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discussed below. for instance, this is a real matrix : a = [ − 1. 3 0. 6 20. 4 5. 5 9. 7 − 6. 2 ]. { \ displaystyle \ mathbf { a } = { \ begin { bmatrix } - 1. 3 & 0. 6 \ \ 20. 4 & 5. 5 \ \ 9. 7 & - 6. 2 \ end { bmatrix } }. } the numbers, symbols, or expressions in the matrix are called its entries or its elements. the horizontal and vertical lines of entries in a matrix are respectively called rows and columns. = = = size = = = the size of a matrix is defined by the number of rows and columns it contains. there is no limit to the number of rows and columns that a matrix ( in the usual sense ) can have as long as they are positive integers. a matrix with m { \ displaystyle m } rows and n { \ displaystyle n } columns is called an m × n { \ displaystyle m \ times n } matrix, or m { \ displaystyle { m } } - by - n { \ displaystyle { n } } matrix, where m { \ displaystyle { m } } and n { \ displaystyle { n } } are called its dimensions. for example, the matrix a { \ displaystyle { \ mathbf { a } } } above is a 3 × 2 { \ displaystyle { 3 \ times 2 } } matrix. matrices with a single row are called row matrices or row vectors, and those with a single column are called column matrices or column vectors. a matrix with the same number of rows and columns is called a square matrix. a matrix with an infinite number of rows or columns ( or both ) is called an infinite matrix. in some contexts, such as computer algebra programs, it is useful to consider a matrix with no rows or no columns, called an empty matrix. = = notation = = the specifics of symbolic matrix notation vary widely, with some prevailing trends. matrices are commonly written in square brackets or parentheses, so that an m × n { \ displaystyle m \ times n } matrix a { \ displaystyle \ mathbf { a } } is represented as a = [ a 11 a 12 a 1 n a 21 a 22 a 2 n a m 1 a m 2 a m n ] = ( a 11 a 12 a 1 n a 21 a 22 a 2 n
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https://en.wikipedia.org/wiki/Matrix_(mathematics)
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a $ k $ - artal arrangement is a reducible algebraic curve composed of a smooth cubic and $ k $ inflectional tangents. by studying the topological properties of their subarrangements, we prove that for $ k = 3, 4, 5, 6 $, there exist zariski pairs of $ k $ - artal arrangements. these zariki pairs can be distinguished in a geometric way by the number of collinear triples in the set of singular points contained in the cubic.
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arxiv:1607.07618
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in this article, we give a method of calculating the automorphism groups of the vertex operator algebras $ v _ l ^ + $ associated with even lattices $ l $. for example, by using this method we determine the automorphism groups of $ v _ l ^ + $ for even lattices of rank one, two and three, and even unimodular lattices.
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arxiv:math/0507255
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we study the detection of change - points in time series. the classical cusum statistic for detection of jumps in the mean is known to be sensitive to outliers. we thus propose a robust test based on the wilcoxon two - sample test statistic. the asymptotic distribution of this test can be derived from a functional central limit theorem for two - sample u - statistics. we extend a theorem of csorgo and horvath to the case of dependent data.
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arxiv:1304.2479
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we obtain a dual representation of the kantorovich functional defined for functions on the skorokhod space using quotient sets. our representation takes the form of a choquet capacity generated by martingale measures satisfying additional constraints to ensure compatibility with the quotient sets. these sets contain stochastic integrals defined pathwise and two such definitions starting with simple integrands are given. another important ingredient of our analysis is a regularized version of jakubowski ' s $ s $ - topology on the skorokhod space.
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arxiv:1904.04644
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we establish a reversal of lyapunov ' s inequality for monotone log - concave sequences, settling a conjecture of havrilla - tkocz and melbourne - tkocz. a strengthened version of the same conjecture is disproved through counter example. we also derive several information theoretic inequalities as consequences. in particular sharp bounds are derived for the varentropy, r \ ' enyi entropies, and the concentration of information of monotone log - concave random variables. moreover, the majorization approach utilized in the proof of the main theorem, is applied to derive analogous information theoretic results in the symmetric setting, where the lyapunov reversal is known to fail.
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arxiv:2111.06997
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assignment, he applied for a position under the chief accountant of the madras port trust. in a letter dated 9 february 1912, ramanujan wrote : sir, i understand there is a clerkship vacant in your office, and i beg to apply for the same. i have passed the matriculation examination and studied up to the f. a. but was prevented from pursuing my studies further owing to several untoward circumstances. i have, however, been devoting all my time to mathematics and developing the subject. i can say i am quite confident i can do justice to my work if i am appointed to the post. i therefore beg to request that you will be good enough to confer the appointment on me. attached to his application was a recommendation from e. w. middlemast, a mathematics professor at the presidency college, who wrote that ramanujan was " a young man of quite exceptional capacity in mathematics ". three weeks after he applied, on 1 march, ramanujan learned that he had been accepted as a class iii, grade iv accounting clerk, making 30 rupees per month. at his office, ramanujan easily and quickly completed the work he was given and spent his spare time doing mathematical research. ramanujan ' s boss, sir francis spring, and s. narayana iyer, a colleague who was also treasurer of the indian mathematical society, encouraged ramanujan in his mathematical pursuits. = = = contacting british mathematicians = = = in the spring of 1913, narayana iyer, ramachandra rao and e. w. middlemast tried to present ramanujan ' s work to british mathematicians. m. j. m. hill of university college london commented that ramanujan ' s papers were riddled with holes. he said that although ramanujan had " a taste for mathematics, and some ability ", he lacked the necessary educational background and foundation to be accepted by mathematicians. although hill did not offer to take ramanujan on as a student, he gave thorough and serious professional advice on his work. with the help of friends, ramanujan drafted letters to leading mathematicians at cambridge university. the first two professors, h. f. baker and e. w. hobson, returned ramanujan ' s papers without comment. on 16 january 1913, ramanujan wrote to g. h. hardy, whom he knew from studying orders of infinity ( 1910 ). coming from an unknown mathematician, the nine pages of mathematics made hardy initially view ramanujan '
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https://en.wikipedia.org/wiki/Srinivasa_Ramanujan
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it is shown that if a distribution v of exponential growth has support in a proper convex cone and its fourier transform is carried by a closed cone different from whole space, then v = 0. the application of this result to a { \ em quasi - local } quantum field theory ( where the fields are localizable only in regions greater than a certain scale of nonlocality ) is contemplated. in particular, we show that a number of physically important predictions of { \ em local } quantum field theory also hold in a quantum field theory with a fundamental length, as indicated from string theory.
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arxiv:0708.0652
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the constraint of incompressibility is often used to simplify the magnetohydrodynamic ( mhd ) description of linearized plasma dynamics because it does not affect the ideal mhd marginal stability point. in this paper two methods for introducing incompressibility are compared in a cylindrical plasma model : in the first method, the limit $ \ gamma \ to \ infty $ is taken, where $ \ gamma $ is the ratio of specific heats ; in the second, an anisotropic mass tensor $ \ mathbf { \ rho } $ is used, with the component parallel to the magnetic field taken to vanish, $ \ rho _ { \ parallel } \ to 0 $. use of resistive mhd reveals the nature of these two limits because the alfv \ ' en and slow magnetosonic continua of ideal mhd are converted to point spectra and moved into the complex plane. both limits profoundly change the slow - magnetosonic spectrum, but only the second limit faithfully reproduces the resistive alfv \ ' en spectrum and its wavemodes. in ideal mhd, the slow magnetosonic continuum degenerates to the alfv \ ' en continuum in the first method, while it is moved to infinity by the second. the degeneracy in the first is broken by finite resistivity. for numerical and semi - analytical study of these models, we choose plasma equilibria which cast light on puzzling aspects of results found in earlier literature.
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arxiv:physics/0405002
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we introduce a layout similarity measure designed to evaluate the results of layout generation. while several similarity measures have been proposed in prior research, there has been a lack of comprehensive discussion about their behaviors. our research uncovers that the majority of these measures are unable to handle various layout differences, primarily due to their dependencies on strict element matching, that is one - by - one matching of elements within the same category. to overcome this limitation, we propose a new similarity measure based on optimal transport, which facilitates a more flexible matching of elements. this approach allows us to quantify the similarity between any two layouts even those sharing no element categories, making our measure highly applicable to a wide range of layout generation tasks. for tasks such as unconditional layout generation, where fid is commonly used, we also extend our measure to deal with collection - level similarities between groups of layouts. the empirical result suggests that our collection - level measure offers more reliable comparisons than existing ones like fid and max. iou.
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arxiv:2407.12356
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a class of black objects which are solutions of pure gravity with negative cosmological constant are classified through the mapping between the killing spinors of the ground state and those of the transverse section. it is shown that these geometries must have transverse sections of constant curvature for spacetime dimensions d below seven. for d > 6, the transverse sections can also be euclidean einstein manifolds. in even dimensions, spacetimes with transverse section of nonconstant curvature exist only in d = 8 and 10. this classification goes beyond standard supergravity and the eleven dimensional case is analyzed. it is shown that if the transverse section has negative scalar curvature, only extended objects can have a supersymmetric ground state. in that case, some solutions are explicitly found whose ground state resembles a wormhole.
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arxiv:hep-th/0204029
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the electron doping of undoped high - $ t _ c $ cuprates via the transfer of charge from manganites ( or other oxides ) using heterostructure geometries is here theoretically discussed. this possibility is mainly addressed via a detailed analysis of photoemission and diffusion voltage experiments, which locate the fermi level of manganites above the bottom of the upper hubbard band of some cuprate parent compounds. a diagram with the relative location of fermi levels and gaps for several oxides is presented. the procedure discussed here is generic, allowing for the qualitative prediction of the charge flow direction at several oxide interfaces. the addition of electrons to antiferromagnetic cu oxides may lead to a superconducting state at the interface with minimal quenched disorder. model calculations using static and dynamical mean - field theory, supplemented by a poisson equation formalism to address charge redistribution at the interface, support this view. the magnetic state of the manganites could be antiferromagnetic or ferromagnetic. the former is better to induce superconductivity than the latter, since the spin - polarized charge transfer will be detrimental to singlet superconductivity. it is concluded that in spite of the robust hubbard gaps, the electron doping of undoped cuprates at interfaces appears possible, and its realization may open an exciting area of research in oxide heterostructures.
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arxiv:0705.0498
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in situ electron microscopy is a key tool for understanding the mechanisms driving novel phenomena in 2d structures. unfortunately, due to various practical challenges, technologically relevant 2d heterostructures prove challenging to address with electron microscopy. here, we use the differential phase contrast imaging technique to build a methodology for probing local electrostatic fields during electrical operation with nanoscale precision in such materials. we find that by combining a traditional dpc setup with a high pass filter, we can largely eliminate electric fluctuations emanating from short - range atomic potentials. with this method, a priori electric field expectations can be directly compared with experimentally derived values to readily identify inhomogeneities and potentially problematic regions. we use this platform to analyze the electric field and charge density distribution across layers of hbn and mos2.
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arxiv:2012.13842
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graphite is a ubiquitous electrode material with particular promise for use in e. g., energy storage and desalination devices, but very little is known about the properties of the graphite - electrolyte double layer at technologically relevant concentrations. here, the ( electrified ) graphite - nacl ( aq ) interface was examined using constant chemical potential molecular dynamics simulations ; this approach avoids ion depletion ( due to surface adsorption ) and maintains a constant concentration of ions beyond the surface. specific na + adsorption at the graphite basal surface causes charging of the interface in the absence of an applied potential. at moderate bulk concentrations, this leads to accumulation of counter - ions in a diffuse layer to balance the effective surface charge, consistent with established models of the electrical double layer ( dl ). beyond 0. 6 m, however, a combination of over - screening and ion crowding in the dl results in alternating compact layers of ion density perpendicular to the interface. the transition to this regime is marked by an increasing dl size and anomalous negative shifts to the potential of zero charge with incremental changes to the bulk concentration. our observations are supported by changes to the position of the differential capacitance minimum measured by electrochemical impedance spectroscopy. furthermore, a striking level of agreement between the differential capacitance from simulations and experiments allows us to critically assess the accepted norm that electrochemical capacitance measurements report simply on the density of states of the graphite material. finally, ion crowding at the highest concentrations ( beyond 5 m ) leads to the formation of liquid - like nacl clusters confined to highly non - ideal regions of the double layer, where ion diffusion is up to five times slower than in the bulk.
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arxiv:2104.11773
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we present the first spectroscopic images of solar radio transients from the prototype for the murchison widefield array ( mwa ), observed on 2010 march 27. our observations span the instantaneous frequency band 170. 9 - 201. 6 mhz. though our observing period is characterized as a period of ` low ' to ` medium ' activity, one broadband emission feature and numerous short - lived, narrowband, non - thermal emission features are evident. our data represent a significant advance in low radio frequency solar imaging, enabling us to follow the spatial, spectral, and temporal evolution of events simultaneously and in unprecedented detail. the rich variety of features seen here reaffirms the coronal diagnostic capability of low radio frequency emission and provides an early glimpse of the nature of radio observations that will become available as the next generation of low frequency radio interferometers come on - line over the next few years.
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arxiv:1101.0620
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the authors found necessary and sufficient conditions for samuelson ' s web to be of maximum rank.
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arxiv:0910.4749
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sea ice is a crucial component of the earth ' s climate system and is highly sensitive to changes in temperature and atmospheric conditions. accurate and timely measurement of sea ice parameters is important for understanding and predicting the impacts of climate change. nevertheless, the amount of satellite data acquired over ice areas is huge, making the subjective measurements ineffective. therefore, automated algorithms must be used in order to fully exploit the continuous data feeds coming from satellites. in this paper, we present a novel approach for sea ice segmentation based on sar satellite imagery using hybrid convolutional transformer ( convtr ) networks. we show that our approach outperforms classical convolutional networks, while being considerably more efficient than pure transformer models. convtr obtained a mean intersection over union ( miou ) of 63. 68 % on the ai4arctic data set, assuming an inference time of 120ms for a 400 x 400 squared km product.
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arxiv:2306.07649
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we consider a dynamic situation in the weighted bipartite matching problem : edge weights in the input graph are repeatedly updated and we are asked to maintain an optimal matching at any moment. a trivial approach is to compute an optimal matching from scratch each time an update occurs. in this paper, we show that if each update occurs locally around a single vertex, then a single execution of dijkstra ' s algorithm is sufficient to preserve optimality with the aid of a dual solution. as an application of our result, we provide a faster implementation of the envy - cycle procedure for finding an envy - free allocation of indivisible items. our algorithm runs in $ \ mathrm { o } ( mn ^ 2 ) $ time, while the known bound of the original one is $ \ mathrm { o } ( mn ^ 3 ) $, where $ n $ and $ m $ denote the numbers of agents and items, respectively.
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arxiv:2208.11325
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in the next few years, we are going to probe the low - redshift universe with unprecedented accuracy. among the various fruits that this will bear, it will greatly improve our knowledge of the dynamics of dark energy, though for this there is a strong theoretical preference for a cosmological constant. we assume that dark energy is described by the so - called effective field theory of dark energy, which assumes that dark energy is the goldstone boson of time translations. such a formalism makes it easy to ensure that our signatures are consistent with well - established principles of physics. since most of the information resides at high wavenumbers, it is important to be able to make predictions at the highest wavenumber that is possible. the effective field theory of large - scale structure ( eftoflss ) is a theoretical framework that has allowed us to make accurate predictions in the mildly non - linear regime. in this paper, we derive the non - linear equations that extend the eftoflss to include the effect of dark energy both on the matter fields and on the biased tracers. for the specific case of clustering quintessence, we then perturbatively solve to cubic order the resulting non - linear equations and construct the one - loop power spectrum of the total density contrast.
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arxiv:1611.07966
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it seems to be expected, that a horizon of a quasi - local type, like a killing or an isolated horizon, by analogy with a globally defined event horizon, should be unique in some open neighborhood in the spacetime, provided the vacuum einstein or the einstein - maxwell equations are satisfied. the aim of our paper is to verify whether that intuition is correct. if one can extend a so called kundt metric, in such a way that its null, shear - free surfaces have spherical spacetime sections, the resulting spacetime is foliated by so called non - expanding horizons. the obstacle is kundt ' s constraint induced at the surfaces by the einstein or the einstein - maxwell equations, and the requirement that a solution be globally defined on the sphere. we derived a transformation ( reflection ) that creates a solution to kundt ' s constraint out of data defining an extremal isolated horizon. using that transformation, we derived a class of exact solutions to the einstein or einstein - maxwell equations of very special properties. each spacetime we construct is foliated by a family of the killing horizons. moreover, it admits another, transversal killing horizon. the intrinsic and extrinsic geometry of the transversal killing horizon coincides with the one defined on the event horizon of the extremal kerr - newman solution. however, the killing horizon in our example admits yet another killing vector tangent to and null at it. the geometries of the leaves are given by the reflection.
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arxiv:gr-qc/0306107
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strange quark matter in a color flavor locked ( cfl ) state can be the true ground state of hadronic matter for a much wider range of the parameters of the model ( the gap of the qcd cooper pairs $ \ delta $, the strange quark mass $ m _ s $ and the bag constant $ b $ ) than the state without any pairing. we review the equation of state ( eos ) of cfl strange matter and study the structure of stellar objects made up of this phase, highlighting the novel features of the latter. although the effects of pairing on the equation of state are thought to be small, we find that cfl stars may be in fact much more compact than strange stars ( ss ). this feature may be relevant in view of some recent observation claiming the existence of exotic and / or deconfined phases in some nearby neutron stars ( ns ).
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arxiv:astro-ph/0211638
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we study the spectral rigidity of the non - hermitian analog of the anderson model suggested by tzortzakakis, makris and economou ( tme ). this is a $ l \ times l \ times l $ tightly bound cubic lattice, where both real and imaginary parts of on - site energies are independent random variables uniformly distributed between $ - w / 2 $ and $ w / 2 $. the tme model may be used to describe a random laser. in a recent paper we proved that this model has the anderson transition at $ w = w _ c \ simeq 6 $ in three dimension. here we numerically diagonalize tme $ l \ times l \ times l $ cubic lattice matrices and calculate the number variance of eigenvalues in a disk of their complex plane. we show that on the metallic side $ w < 6 $ of the anderson transition, complex eigenvalues repel each other as strongly as in the complex ginibre ensemble only in a disk containing $ n _ c ( l, w ) $ eigenvalues. we find that $ n _ c ( l, w ) $ is proportional to $ l $ and grows with decreasing $ w $ similarly to the number of energy levels $ n _ c $ in the thouless energy band of the anderson model.
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arxiv:2007.02380
|
the icecube collaboration has built an in - ice neutrino telescope and a surface detector array, icetop, at the south pole. over 5000 digital optical modules have been deployed in a cubic kilometer of ice between 1450 and 2450 m below the surface. the novel observatory provides a new window to explore the universe. the combination of cutting - edge discovery science and the exotic antarctic environment is an ideal vehicle to excite and engage a wide audience. examples of how the international icecube collaboration has brought the universe to a broader audience via the south pole are described.
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arxiv:1110.1600
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