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in the under - to optimal - doping regimes of electron - doped cuprates, it was theoretically suspected that there is a coexistence of superconducting ( sc ) and antiferromagnetic ( afm ) orders. the quasi - particle excitations could be gapped by both orders, and the effective gap is non - monotonic d - wave - like in the momentum space. alternatively the gap was also speculated as a pure pairing gap. using an effective microscopic model, we consider the manifestation of the quasi - particle gap in the electronic raman spectra in a range of doping levels, where the relative strength of the sc and afm order parameters varies. we demonstrate that from the electronic raman spectra the effective single - particle gap can be disentangled into contributions from the two distinctive orders. this would help to tell whether the non - monotonic gap is due to the coexistence of sc and afm orders.
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arxiv:cond-mat/0610724
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population - based metaheuristic algorithms are powerful tools in the design of neutron scattering instruments and the use of these types of algorithms for this purpose is becoming more and more commonplace. today there exists a wide range of algorithms to choose from when designing an instrument and it is not always initially clear which may provide the best performance. furthermore, due to the nature of these types of algorithms, the final solution found for a specific design scenario cannot always be guaranteed to be the global optimum. therefore, to explore the potential benefits and differences between the varieties of these algorithms available, when applied to such design scenarios, we have carried out a detailed study of some commonly used algorithms. for this purpose, we have developed a new general optimization software package which combines a number of common metaheuristic algorithms within a single user interface and is designed specifically with neutronic calculations in mind. the algorithms included in the software are implementations of particle - swarm optimization ( pso ), differential evolution ( de ), artificial bee colony ( abc ), and a genetic algorithm ( ga ). the software has been used to optimize the design of several problems in neutron optics and shielding, coupled with monte - carlo simulations, in order to evaluate the performance of the various algorithms. generally, the performance of the algorithms depended on the specific scenarios, however it was found that de provided the best average solutions in all scenarios investigated in this work.
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arxiv:1908.07221
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by parametrizing input and state trajectories with basis functions different approximations to the constrained linear quadratic regulator problem are obtained. these notes present and discuss technical results that are intended to supplement a corresponding journal article. the results can be applied in a model predictive control context.
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arxiv:1803.05510
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this paper presents results of a pilot study that explored the potential of morse code as a method for text entry on mobile devices. in the study, participants without prior experience with morse code reached 6. 7 wpm with a morse code keyboard in three short sessions. learning was observed both in terms of text entry speed and accuracy, which suggests that the overall performance of the keyboard is likely to improve with practice.
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arxiv:2012.06708
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the model problem of scattering of a sound wave by an infinite plane structure formed by a semi - infinite acoustically hard screen and a semi - infinite sandwich panel perforated from one side and covered by a membrane from the other is exactly solved. the model is governed by two helmholtz equations for the velocity potentials in the upper and lower half - planes coupled by the leppington effective boundary condition and the equation of vibration of a membrane in a fluid. two methods of solution are proposed and discussed. both methods reduce the problem to an order - 2 vector riemann - hilbert problem. the matrix coefficients have different entries, have the chebotarev - khrapkov structure and share the same order - 4 characteristic polynomial. exact wiener - hopf matrix factorization requires solving a scalar riemann - hilbert on an elliptic surface and the associated genus - 1 jacobi inversion problem solved in terms of the associated riemann $ \ theta $ - function. numerical results for the absolute value of the total velocity potentials are reported and discussed.
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arxiv:2304.04678
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this paper presents a quasi - deterministic ray tracing ( qd - rt ) method for analyzing the propagation of electromagnetic waves in street canyons. the method uses a statistical bistatic distribution to model the radar cross section ( rcs ) of various irregular objects such as cars and pedestrians, instead of relying on exact values as in a deterministic propagation model. the performance of the qd - rt method is evaluated by comparing its generated path loss distributions to those of the deterministic ray tracing ( d - rt ) model using the two - sample cramer - von mises test. the results indicate that the qd - rt method generates the same path loss distributions as the d - rt model while offering lower complexity. this study suggests that the qd - rt method has the potential to be used for analyzing complicated scenarios such as street canyon scenarios in mmwave wireless communication systems.
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arxiv:2307.04498
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the calculation of most objective speech intelligibility assessment metrics requires clean speech as a reference. such a requirement may limit the applicability of these metrics in real - world scenarios. to overcome this limitation, we propose a deep learning - based non - intrusive speech intelligibility assessment model, namely stoi - net. the input and output of stoi - net are speech spectral features and predicted stoi scores, respectively. the model is formed by the combination of a convolutional neural network and bidirectional long short - term memory ( cnn - blstm ) architecture with a multiplicative attention mechanism. experimental results show that the stoi score estimated by stoi - net has a good correlation with the actual stoi score when tested with noisy and enhanced speech utterances. the correlation values are 0. 97 and 0. 83, respectively, for the seen test condition ( the test speakers and noise types are involved in the training set ) and the unseen test condition ( the test speakers and noise types are not involved in the training set ). the results confirm the capability of stoi - net to accurately predict the stoi scores without referring to clean speech.
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arxiv:2011.04292
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based on the collected multiwavelength data, namely in the radio ( nvss, first, ratan - 600 ), ir ( wise ), optical ( pan - starrs ), uv ( galex ), and x - ray ( rosat, swift - xrt ) ranges, we have performed a cluster analysis for the blazars of the roma - bzcat catalog. using two machine learning methods, namely a combination of pca with k - means clustering and kohonen ' s self - organizing maps, we have constructed an independent classification of the blazars ( five classes ) and compared the classes with the known roma - bzcat classification ( fsrqs, bl lacs, galaxy - dominated bl lacs, and blazars of an uncertain type ) as well as with the high synchrotron peaked blazars ( hsp ) from the 3hsp catalog and blazars from the tevcat catalog. the obtained groups demonstrate concordance with the bl lac / fsrq classification along with a continuous character of the change in the properties. the group of hsp blazars stands out against the overall distribution. we examine the characteristics of the five groups and demonstrate distinctions in their spectral energy distribution shapes. the effectiveness of the clustering technique for objective analysis of multiparametric arrays of experimental data is demonstrated.
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arxiv:2404.09667
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we calculate the amplitude of the rare flavour - changing neutral - current decay $ b \ to \ pi \ ell ^ + \ ell ^ - $ at large recoil of the pion. the nonlocal contributions in which the weak effective operators are combined with the electromagnetic lepton - pair emission are systematically taken into account. these amplitudes are calculated at off - shell values of the lepton - pair mass squared, $ q ^ 2 < 0 $, employing the operator - product expansion, qcd factorization and light - cone sum rules. the results are fitted to hadronic dispersion relations in $ q ^ 2 $, including the intermediate vector meson contributions. the dispersion relations are then used in the physical region $ q ^ 2 > 0 $. our main result is the process - dependent addition $ \ delta c ^ { ( b \ pi ) } _ 9 ( q ^ 2 ) $ to the wilson coefficient $ c _ 9 $ obtained at $ 4m _ \ ell ^ 2 < q ^ 2 \ lesssim m _ { j / \ psi } ^ 2 $. together with the $ b \ to \ pi $ form factors from light - cone sum rules, this quantity is used to predict the differential rate, direct cp - asymmetry and isospin asymmetry in $ b \ to \ pi \ ell ^ + \ ell ^ - $. we also estimate the total rate of the rare decay $ b \ to \ pi \ nu \ bar { \ nu } $.
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arxiv:1506.07760
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in this paper we prove a sequential convergence result for blowup solutions to the $ m $ - equivariant, self - dual chern - - simons - - schr { \ " o } dinger equation. we show that if $ u $ has mass less than twice the mass of the soliton, a blowup solution converges to the soliton along a subsequence of times that converges to the blowup time.
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arxiv:2309.10925
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we present the results of radio continuum and molecular line observations conducted using the mopra millimetre - wave telescope and australia telescope compact array. these observations reveal the presence of a dense core embedded within each cloud, and the presence of a layer of hot ionised gas coincided with their bright - rims. the ionised gas has electron densities significantly higher than the critical density above which an ionised boundary layer can form and be maintained, strongly supporting the hypothesis that these clouds are being photoionised by the nearby ob star ( s ). from an evaluation of the pressure balance between the ionised and molecular gas, sfo 58 and sfo 68 are identified as being in a post - pressure balance state, while sfo 75 and sfo 76 are more likely to be in a pre - pressure balance state. we find secondary evidence for the presence of ongoing star formation within sfo 58 and sfo 68, such as molecular outflows, oh, h $ _ 2 $ o and methanol masers, and identify a potential embedded uc hii region, but find no evidence for any ongoing star formation within sfo 75 and sfo 76. our results are consistent with the star formation within sfo 58 and sfo 68 having been triggered by the radiatively driven implosion of these clouds.
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arxiv:astro-ph/0601718
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we investigate the quantitative uniqueness of solutions to parabolic equations with lower order terms on compact smooth manifolds. quantitative uniqueness is a quantitative form of strong unique continuation property. we characterize quantitative uniqueness by the rate of vanishing. we can obtain the vanishing order of solutions by $ c ^ { 1, 1 } $ norm of the potential functions, as well as the $ l ^ \ infty $ norm of the coefficient functions. some quantitative carleman estimates and three cylinder inequalities are established.
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arxiv:1708.01899
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we consider the problem of detecting the dimensionality of entanglement with the use of correlations between measurements in randomized directions. first, exploiting the recently derived covariance matrix criterion for the entanglement dimensionality [ s. liu et al., arxiv : 2208. 04909 ], we derive an inequality that resembles well - known entanglement criteria, but contains different bounds for the different dimensionalities of entanglement. this criterion is invariant under local changes of $ su ( d ) $ bases and can be used to find regions in the space of moments of randomized correlations, generalizing the results of [ s. imai et al., phys. rev. lett. 126, 150501 ( 2021 ) ] to the case of entanglement - dimensionality detection. in particular, we find analytical boundary curves for the different entanglement dimensionalities in the space of second - and fourth - order moments of randomized correlations for all dimensions $ d _ a = d _ b = d $ of a bipartite system. we then show how our method works in practice, also considering a finite statistical sample of correlations, and we also show that it can detect more states than other entanglement - dimensionality criteria available in the literature, thus providing a method that is both very powerful and potentially simpler in practical scenarios. we conclude by discussing the partly open problem of the implementation of our method in the multipartite scenario.
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arxiv:2211.09614
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separable nucleon - nucleon potentials are calculated using inverse scattering techniques as presented in previously published work. the dependence of the potentials on the momentum cut - off of the scattering phase - shifts is studied. some comparison is made with the v - low - k potential. the effect of the cut - off on nuclear matter binding energy calculated by standard brueckner theory is also presented. it is foumd that a cut - off larger than about 4 fm - 1 will keep the error to within one mev around saturation density. while the potentials are cut - off dependent the effective interaction represented by the brueckner k - matrix is less sensitive to this cut - off. this is in particular found to be the case for the 1s0 state.
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arxiv:nucl-th/0511030
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every smooth minimal complex algebraic surface of general type, $ x $, may be mapped into a moduli space, $ \ mm _ { c _ 1 ^ 2 ( x ), c _ 2 ( x ) } $, of minimal surfaces of general type, all of which have the same chern numbers. using the braid group and braid monodromy, we construct infinitely many new examples of pairs of minimal surfaces of general type which have the same chern numbers and non - isomorphic fundamental groups. unlike previous examples, our results include $ x $ for which $ | \ pi _ 1 ( x ) | $ is arbitrarily large. moreover, the surfaces are of positive signature. this supports our goal of using the braid group and fundamental groupsto decompose $ \ mm _ { c _ 1 ^ 2 ( x ), c _ 2 ( x ) } $ into connected components.
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arxiv:alg-geom/9703005
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in this paper, we study the problem of data augmentation for language understanding in task - oriented dialogue system. in contrast to previous work which augments an utterance without considering its relation with other utterances, we propose a sequence - to - sequence generation based data augmentation framework that leverages one utterance ' s same semantic alternatives in the training data. a novel diversity rank is incorporated into the utterance representation to make the model produce diverse utterances and these diversely augmented utterances help to improve the language understanding module. experimental results on the airline travel information system dataset and a newly created semantic frame annotation on stanford multi - turn, multidomain dialogue dataset show that our framework achieves significant improvements of 6. 38 and 10. 04 f - scores respectively when only a training set of hundreds utterances is represented. case studies also confirm that our method generates diverse utterances.
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arxiv:1807.01554
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in this paper we study the well - posedness of a simple model of boundary layer for rotating fluids between two concentric spheres near the equator. we show that this model can be seen as a degenerate elliptic equation, for which we prove an existence result thanks to a lax - milgram type lemma. we also prove uniqueness under an additional integrability assumption and present a transparent boundary condition for such layers.
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arxiv:1812.09185
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electrons in graphene have four flavors associated with low - energy spin and valley degrees of freedom. the fractional quantum hall effect in graphene is dominated by long - range coulomb interactions which are invariant under rotations in spin - valley space. this su ( 4 ) symmetry is spontaneously broken at most filling factors, and also weakly broken by atomic scale valley - dependent and valley - exchange interactions with coupling constants $ g _ { z } $ and $ g _ { \ perp } $. in this paper we demonstrate that when $ g _ { z } = - g _ { \ perp } $ an exact so ( 5 ) symmetry survives which unifies the n \ ' eel spin order parameter of the antiferromagnetic state and the $ xy $ valley order parameter of the kekul \ ' e distortion state into a single five - component order parameter. the proximity of the highly insulating quantum hall state observed in graphene at $ \ nu = 0 $ to an ideal so ( 5 ) symmetric quantum hall state remains an open experimental question. we illustrate the physics associated with this so ( 5 ) symmetry by studying the multiplet structure and collective dynamics of filling factor $ \ nu = 0 $ quantum hall states based on exact - diagonalization and low - energy effective theory approaches. this allows to illustrate how manifestations of the so ( 5 ) symmetry would survive even when it is weakly broken.
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arxiv:1406.2330
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we study vector - tensor theories in which a 4 - dimensional vector field $ a _ { \ mu } $ is coupled to a vector quantity $ { \ cal j } ^ { \ mu } $, which is expressed in terms of $ a _ { \ mu } $ and a metric tensor $ g _ { \ mu \ nu } $. the divergence of $ { \ cal j } ^ { \ mu } $ is equivalent to a gauss - bonnet ( gb ) term. we show that an interacting lagrangian of the form $ f ( x ) a _ { \ mu } { \ cal j } ^ { \ mu } $, where $ f $ is an arbitrary function of $ x = - ( 1 / 2 ) a _ { \ mu } a ^ { \ mu } $, belongs to a scheme of beyond generalized proca theories. for $ f ( x ) = \ alpha = { \ rm constant } $, this interacting lagrangian reduces to a particular class of generalized proca theories. we apply the latter coupling to a static and spherically symmetric vacuum configuration by incorporating the einstein - hilbert term, maxwell scalar, and vector mass term $ \ eta x $ ( $ \ eta $ is a constant ). under an expansion of the small coupling constant $ \ alpha $ with $ \ eta \ neq 0 $, we derive hairy black hole solutions endowed with nonvanishing temporal and radial vector field profiles. the asymptotic properties of solutions around the horizon and at spatial infinity are different from those of hairy black holes present in scalar - gb theories. we also show that black hole solutions without the vector mass term, i. e., $ \ eta = 0 $, are prone to ghost instability of odd - parity perturbations.
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arxiv:2303.13717
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aims : we investigate the spatial distribution of dust emission around tycho ' s snr to understand its origin. we distinguish the dust associated with the snr from that of the surrounding ism. methods : we performed mid - to far - infrared imaging observations of the remnant at wavelengths of 9, 15, 18, 24, 65, 90, 140, and 160um using the infrared camera and the far - infrared surveyor onboard akari. we compared the akari images with the suzaku x - ray image and the 12co image of tycho ' s snr. results : all the akari images except the 9, 140, and 160um band images show a shell - like emission structure with brightness peaks at the north east ( ne ) and north west ( nw ) boundaries, sharply outlining part of the x - ray shell. the 140 and 160um bands are dominated by cold dust emission from the surrounding ism near the ne boundary. conclusion : we conclude that the dust emission at the ne boundary comes from the ambient cloud interacting with the shock front, while the origin of the dust emission at the nw boundary is rather unclear because of the absence of prominent interstellar clouds near the corresponding region. we cannot rule out the possibility that the latter is mostly of an sn ejecta origin.
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arxiv:1009.6047
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modified similarity renormalization of hamiltonians is proposed, that performes by means of flow equations the similarity transformation of hamiltonian in the particle number space. this enables to renormalize in the energy space the field theoretical hamiltonian and makes possible to work in a severe trancated fock space for the renormalized hamiltonian.
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arxiv:hep-th/9707086
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biologically relevant exposure to environmental pollutants often shows a non - linear relationship. for their assessment, as a rule short term concentrations have to be determined instead of long term mean values. this is also the case for the perception of odour. regulatory dispersion models like austal2000 calculate long term mean concentration values ( one - hour ), but provide no information on the fluctuation from this mean. the ratio between a short term mean value ( relevant for odour perception ) and the long term mean value ( calculated by the dispersion model ), called the peak - to - mean value, is usually used to describe these fluctuations. in general, this ratio can be defined in different ways. m \ " uller et al. ( 2012 ), in a comment to schauberger et al. ( 2012 ) which includes a statement that austal2000 uses a constant factor of 4, argue that austal2000 does not apply a peak - to - mean factor and does not calculate odour exceedance probabilities. instead it calculates the frequency of so - called odour - hours by applying the relation between the 90 - percentile of the instantaneous concentration and the hourly mean ( janicke and janicke, 2007a ), not between some peak value and the mean. according to janicke and janicke ( 2007a ), the 90 - percentile of the instantaneous concentration can in practice be estimated with sufficient accuracy from the hourly mean by using a factor of 4. having so far replied to m \ " uller et al. ( 2012 ) we take additionally the opportunity to elaborate a little more on the peak - to - mean concept, especially pointing out that a constant factor independent of the stability of the atmosphere, the distance from and the geometry of the source, is not appropriate. on the contrary it shows a sophisticated structure which cannot be described by only one single value.
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arxiv:1201.0914
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one of the biggest challenges in operating massive multiple - input multiple - output systems is the acquisition of accurate channel state information at the transmitter. to take up this challenge, time division duplex is more favorable thanks to its channel reciprocity between downlink and uplink. however, while the propagation channel over the air is reciprocal, the radio - frequency front - ends in the transceivers are not. therefore, calibration is required to compensate the rf hardware asymmetry. although various over - the - air calibration methods exist to address the above problem, this paper offers a unified representation of these algorithms, providing a higher level view on the calibration problem, and introduces innovations on calibration methods. we present a novel family of calibration methods, based on antenna grouping, which improve accuracy and speed up the calibration process compared to existing methods. we then provide the cram \ ' er - rao bound as the performance evaluation benchmark and compare maximum likelihood and least squares estimators. we also differentiate between coherent and non - coherent accumulation of calibration measurements, and point out that enabling non - coherent accumulation allows the training to be spread in time, minimizing impact to the data service. overall, these results have special value in allowing to design reciprocity calibration techniques that are both accurate and resource - effective.
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arxiv:1710.10830
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type 2 quasars are luminous active galactic nuclei whose central engines are seen through large amounts of gas and dust. we present spitzer spectra of twelve type 2 quasars selected on the basis of their optical emission line properties. within this sample, we find a surprising diversity of spectra, from those that are featureless to those showing strong pah emission, deep silicate absorption at 10 micron, hydrocarbon absorption, high - ionization emission lines and h _ 2 rotational emission lines. about half of the objects in the sample are likely compton - thick, including the two with the deepest si absorption. the median star - formation luminosity of the objects in our sample measured from the strength of the pah features is 5x10 ^ 11 l _ sun, much higher than for field galaxies or for any other agn sample, but similar to other samples of type 2 quasars. this suggests an evolutionary link between obscured quasars and peak star formation activity in the host galaxy. despite the high level of star formation, the bolometric output is dominated by the quasar in all cases. for a given strength of 10 micron si absorption, ulirgs are significantly colder than are type 2 quasars ( their f _ nu [ 14. 5 micron ] / f _ nu [ 27. 5 micron ] ratio is 0. 5 dex lower ), perhaps reflecting different obscuration geometries in these sources. we find that the appearance of the 10 micron feature ( i. e., whether it shows in emission or in absorption ) is well - correlated with the optical classification in type 1 and type 2 quasars, contrary to some models of clumpy obscuration. furthermore, this correlation is significantly stronger in quasars ( l _ bol > 10 ^ 45 erg / s ) than it is in seyfert galaxies ( l _ bol < < 10 ^ 45 erg / s ).
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arxiv:0808.1893
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deep learning - based methods have made significant achievements in music source separation. however, obtaining good results while maintaining a low model complexity remains challenging in super wide - band music source separation. previous works either overlook the differences in subbands or inadequately address the problem of information loss when generating subband features. in this paper, we propose scnet, a novel frequency - domain network to explicitly split the spectrogram of the mixture into several subbands and introduce a sparsity - based encoder to model different frequency bands. we use a higher compression ratio on subbands with less information to improve the information density and focus on modeling subbands with more information. in this way, the separation performance can be significantly improved using lower computational consumption. experiment results show that the proposed model achieves a signal to distortion ratio ( sdr ) of 9. 0 db on the musdb18 - hq dataset without using extra data, which outperforms state - of - the - art methods. specifically, scnet ' s cpu inference time is only 48 % of ht demucs, one of the previous state - of - the - art models.
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arxiv:2401.13276
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this paper explores the semantics of a combinatory fragment of reflect, the lambda - calculus underlying a functional language used by intel corporation for hardware design and verification. reflect is similar to ml, but has a primitive data type whose elements are the abstract syntax trees of reflect expressions themselves. following the lcf paradigm, this is intended to serve as the object language of a higher - order logic theorem prover for specification and reasoning - but one in which object - and meta - languages are unified. the aim is to intermix program evaluation and logical deduction through reflection mechanisms. we identify some difficulties with the semantics of reflect as currently defined, and propose a minimal modification of the type system that avoids these problems.
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arxiv:1309.5742
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motivation : a pan - genome graph represents a collection of genomes and encodes sequence variations between them. it is a powerful data structure for studying multiple similar genomes. sequence - to - graph alignment is an essential step for the construction and the analysis of pan - genome graphs. however, existing algorithms incur runtime proportional to the product of sequence length and graph size, making them inefficient for aligning long sequences against large graphs. results : we propose the graph wavefront alignment algorithm ( gwfa ), a new method for aligning a sequence to a sequence graph. although the worst - case time complexity of gwfa is the same as the existing algorithms, it is designed to run faster for closely matching sequences, and its runtime in practice often increases only moderately with the edit distance of the optimal alignment. on four real datasets, gwfa is up to four orders of magnitude faster than other exact sequence - to - graph alignment algorithms. we also propose a graph pruning heuristic on top of gwfa, which can achieve an additional $ \ sim $ 10 - fold speedup on large graphs. availability : gwfa code is accessible at https : / / github. com / lh3 / gwfa.
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arxiv:2206.13574
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we develop the theory of tamed spaces which are dirichlet spaces with distribution - valued lower bounds on the ricci curvature and investigate these from an eulerian point of view. to this end we analyze in detail singular perturbations of dirichlet form by a broad class of distributions. the distributional ricci bound is then formulated in terms of an integrated version of the bochner inequality using the perturbed energy form and generalizing the well - known bakry - \ ' emery curvature - dimension condition. among other things we show the equivalence of distributional ricci bounds to gradient estimates for the heat semigroup in terms of the feynman - kac semigroup induced by the taming distribution as well as consequences in terms of functional inequalities. we give many examples of tamed spaces including in particular riemannian manifolds with either interior singularities or singular boundary behavior.
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arxiv:2009.03121
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in the first two papers, the author embarked on a study of classes of linear equations over integers satisfying a " farkas - type " property. as the third paper in this study, the present paper deals with another class of linear equations over integers that has a similar " farkas - type " property. furthermore it is shown that if an arbitrary system of equations over integers satisfies the conditions imposed by farkas ' lemma then it has rational solutions of a special type.
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arxiv:1606.07878
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obey sc is a indicative of scale invariance, the opposite is not necessarily satisfied. this suggest that a careful analysis must be done before attribute the sc as a origin of giant fef in experiments.
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arxiv:1607.07401
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consider a realization of a poisson process in r ^ 2 with intensity 1 and take a maximal up / right path from the origin to ( n, n ) consisting of line segments between the points, where maximal means that it contains as many points as possible. the number of points in such a path has fluctuations of order n ^ chi, where chi = 1 / 3 by a result of baik - deift - johansson. here we show that typical deviations of a maximal path from the diagonal x = y is of order n ^ xi with xi = 2 / 3. this is consistent with the scaling identity chi = 2xi - 1, which is believed to hold in many random growth models.
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arxiv:math/9910146
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we study the connection between the bcs pairing model and the inhomogeneous vertex model. the two spectral problems coincide in the quasi - classical limit of the off - shell bethe ansatz of the disordered six vertex model. the latter problem is transformed into an auxiliary spectral problem which corresponds to the diagonalization of the integrals of motion of the bcs model. a generating functional whose quasi classical expansion leads to the constants of motion of the bcs model and in particular the hamiltonian, is identified.
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arxiv:cond-mat/0010349
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we use a simple setup based on an infinite planar slab gain medium with no mirrors to explore the possibility of realizing a recently discovered resonance effect related to the mathematical concept of spectral singularity. in particular we determine the range of the gain coefficient g and the width l of the gain region required to achieve this resonance effect. we outline a method that allows for amplifying waves of desired wavelength by adjusting the gain coefficient ( pumping intensity ). we expect this method to have important practical applications in building tunable lasers
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arxiv:1007.1905
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in this paper, we consider a two - hop amplify - and - forward ( af ) relaying system, where the relay node is energy - constrained and harvests energy from the source node. in the literature, there are three main energy - harvesting ( eh ) protocols, namely, time - switching relaying ( tsr ), power - splitting ( ps ) relaying ( psr ) and ideal relaying receiver ( irr ). unlike the existing studies, in this paper, we consider $ \ alpha $ - $ \ mu $ fading channels. in this respect, we derive accurate unified analytical expressions for the ergodic capacity for the aforementioned protocols over independent but not identically distributed ( i. n. i. d ) $ \ alpha $ - $ \ mu $ fading channels. three special cases of the $ \ alpha $ - $ \ mu $ model, namely, rayleigh, nakagami - mandweibull fading channels were investigated. our analysis is verified through numerical and simulation results. it is shown that finding the optimal value of the ps factor for the psr protocol and the eh time fraction for the tsr protocol is a crucial step in achieving the best network performance.
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arxiv:1712.04748
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grover ' s quantum search algorithm provides a quadratic quantum advantage over classical algorithms across a broad class of unstructured search problems. the original protocol is probabilistic, returning the desired result with significant probability on each query, but in general, requiring several iterations of the algorithm. we present a modified version to return the correct result with certainty without having user control over the quantum search oracle. our deterministic, two - parameter " d2p " protocol utilizes generalized phase rotations replacing the phase inversions after a standard oracle query. the d2p protocol achieves a 100 % success rate in no more than one additional iteration compared to the optimal number of steps in the original grover ' s search enabling the same quadratic speed up. we also provide a visualization using the bloch sphere for enhanced geometric intuition.
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arxiv:2201.00091
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we present the first quantum field theory calculation of the pointwise behaviour of the leading - twist parton distribution amplitudes ( pdas ) of the proton and its lightest radial excitation. the proton ' s pda is a broad, concave function, whose maximum is shifted relative to the peak in qcd ' s conformal limit expression for this pda ; an effect which signals the presence of both scalar and pseudovector diquark correlations in the nucleon, with the scalar generating around 60 % of the proton ' s normalisation. the radial - excitation is constituted similarly, and the pointwise form of its pda, which is negative on a material domain, is the result of marked interference between the contributions from both types of diquark ; particularly, the locus of zeros that highlights its character as a radial excitation. these features originate with the emergent phenomenon of dynamical chiral - symmetry breaking in the standard model.
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arxiv:1711.09101
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a detailed multi - messenger study of the high - energy emission from the galactic plane is possible nowadays thanks to the observations provided by gamma and neutrino telescopes and could be mandatory in order to obtain a consistent scenario. we show the potential of this approach by using the total gamma flux from the inner galactic region measured by hess at $ 1 \, { \ rm tev } $ and in the longitude range $ - 75 ^ \ circ < l < 60 ^ \ circ $. by comparing the observational data with the expected diffuse galactic emission, we highlight the existence of an extended hot region of the gamma sky where the cumulative sources contribution dominates over the diffuse component. this region approximately coincides with the portion of the galactic plane from which a $ \ sim 2 \ sigma $ excess of showers is observed in icecube high energy starting events. in the assumption that hadronic mechanisms are responsible for the observed gamma emission, we estimate the total galactic contribution ( i. e. including both diffuse and the source components ) to the icecube neutrino signal as a function of the spectral index and energy cutoff of the sources, taking also into account the upper limit on a galactic component provided by antares.
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arxiv:1710.01040
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we investigate gas contents of star - forming galaxies associated with protocluster 4c23. 56 at z = 2. 49 by using the redshifted co ( 3 - 2 ) and 1. 1 mm dust continuum with the atacama large millimeter / submillimeter array. the observations unveil seven co detections out of 22 targeted h $ \ alpha $ emitters ( haes ) and four out of 19 in 1. 1 mm dust continuum. they have high stellar mass ( $ m _ { \ star } > 4 \ times 10 ^ { 10 } $ $ m _ { \ odot } $ ) and exhibit a specific star - formation rate typical of main - sequence star forming galaxies at $ z \ sim2. 5 $. different gas mass estimators from co ( 3 - 2 ) and 1. 1 mm yield consistent values for simultaneous detections. the gas mass ( $ m _ { \ rm gas } $ ) and gas fraction ( $ f _ { \ rm gas } $ ) are comparable to those of field galaxies, with $ m _ { \ rm gas } = [ 0. 3, 1. 8 ] \ times10 ^ { 11 } \ times ( \ alpha _ { \ rm co } / ( 4. 36 \ times a ( z ) $ ) ) m $ _ { \ odot } $, where $ \ alpha _ { \ rm co } $ is the co - to - h $ _ 2 $ conversion factor and $ a ( z ) $ the additional correction factor for the metallicity dependence of $ \ alpha _ { \ rm co } $, and $ \ langle f _ { \ rm gas } \ rangle = 0. 53 \ pm 0. 07 $ from co ( 3 - 2 ). our measurements place a constraint on the cosmic gas density of high - $ z $ protoclusters, indicating the protocluster is characterized by a gas density higher than that of the general fields by an order of magnitude. we found $ \ rho ( h _ 2 ) \ sim 5 \ times 10 ^ 9 \, m _ { \ odot } \, { \ rm mpc ^ { - 3 } } $ with the co ( 3 - 2 ) detections. the five alma co detections occur in the region of highest galaxy surface density, where the density positively correlates with global star - forming efficiency ( sfe ) and stellar mass. such correlations imply a potentially critical role of environment on early galaxy
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arxiv:1705.10330
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this commentary discusses a recently proposed measure of heterogeneity of dna sequences and compares with the measures of complexity.
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arxiv:adap-org/9709007
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recent large - scale generative models learned on big data are capable of synthesizing incredible images yet suffer from limited controllability. this work offers a new generation paradigm that allows flexible control of the output image, such as spatial layout and palette, while maintaining the synthesis quality and model creativity. with compositionality as the core idea, we first decompose an image into representative factors, and then train a diffusion model with all these factors as the conditions to recompose the input. at the inference stage, the rich intermediate representations work as composable elements, leading to a huge design space ( i. e., exponentially proportional to the number of decomposed factors ) for customizable content creation. it is noteworthy that our approach, which we call composer, supports various levels of conditions, such as text description as the global information, depth map and sketch as the local guidance, color histogram for low - level details, etc. besides improving controllability, we confirm that composer serves as a general framework and facilitates a wide range of classical generative tasks without retraining. code and models will be made available.
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arxiv:2302.09778
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two - color ratio pyrometry is commonly used to measure the surface temperature of aerospace materials during plasma wind tunnel experiments. however, the effect of the plasma radiation on the measurement accuracy is often neglected. in this paper we formulate a model of the instrument response to analyze the systematic error induced by the gas radiation along the optical path. cfd simulations of the plasma flow field, together with a radiation code, allow to compute the gas spectral radiance within the instrument wavelength range. the measurement error is numerically assessed as a function of the true object temperature and emittance value. our simulations explain the typical behavior observed in experiments, showing that a significant bias can affect the measured temperature during the material heating phase. for an actual experiment on a ceramic - matrix composite, a correction to the measured data is proposed, while comparative measurements with a spectrometer corroborate the results.
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arxiv:2309.17254
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l. moret - bailly constructed families $ \ mathfrak { c } \ rightarrow \ mathbb { p } ^ 1 $ of genus 2 curves with supersingular jacobian. in this paper we first classify the reducible fibers of a moret - bailly family using linear algebra over a quaternion algebra. the main result is an algorithm that exploits properties of two reducible fibers to compute a hyperelliptic model for any irreducible fiber of a moret - bailly family.
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arxiv:2105.13752
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text - to - image generation has shown remarkable progress with the emergence of diffusion models. however, these models often generate factually inconsistent images, failing to accurately reflect the factual information and common sense conveyed by the input text prompts. we refer to this issue as image hallucination. drawing from studies on hallucinations in language models, we classify this problem into three types and propose a methodology that uses factual images retrieved from external sources to generate realistic images. depending on the nature of the hallucination, we employ off - the - shelf image editing tools, either instructpix2pix or ip - adapter, to leverage factual information from the retrieved image. this approach enables the generation of images that accurately reflect the facts and common sense.
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arxiv:2407.10683
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, quantifiers may only be nested to finite depths, as in first - order logic, but formulas may have finite or countably infinite conjunctions and disjunctions within them. thus, for example, it is possible to say that an object is a whole number using a formula of l ω 1, ω { \ displaystyle l _ { \ omega _ { 1 }, \ omega } } such as ( x = 0 ) ∨ ( x = 1 ) ∨ ( x = 2 ) ∨. { \ displaystyle ( x = 0 ) \ lor ( x = 1 ) \ lor ( x = 2 ) \ lor \ cdots. } higher - order logics allow for quantification not only of elements of the domain of discourse, but subsets of the domain of discourse, sets of such subsets, and other objects of higher type. the semantics are defined so that, rather than having a separate domain for each higher - type quantifier to range over, the quantifiers instead range over all objects of the appropriate type. the logics studied before the development of first - order logic, for example frege ' s logic, had similar set - theoretic aspects. although higher - order logics are more expressive, allowing complete axiomatizations of structures such as the natural numbers, they do not satisfy analogues of the completeness and compactness theorems from first - order logic, and are thus less amenable to proof - theoretic analysis. another type of logics are fixed - point logics that allow inductive definitions, like one writes for primitive recursive functions. one can formally define an extension of first - order logic — a notion which encompasses all logics in this section because they behave like first - order logic in certain fundamental ways, but does not encompass all logics in general, e. g. it does not encompass intuitionistic, modal or fuzzy logic. lindstrom ' s theorem implies that the only extension of first - order logic satisfying both the compactness theorem and the downward lowenheim – skolem theorem is first - order logic. = = = nonclassical and modal logic = = = modal logics include additional modal operators, such as an operator which states that a particular formula is not only true, but necessarily true. although modal logic is not often used to axiomatize mathematics, it has been used to study the properties of first - order pro
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https://en.wikipedia.org/wiki/Mathematical_logic
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there is a critical need for efficient and reliable active flow control strategies to reduce drag and noise in aerospace and marine engineering applications. while traditional full - order models based on the navier - stokes equations are not feasible, advanced model reduction techniques can be inefficient for active control tasks, especially with strong non - linearity and convection - dominated phenomena. using convolutional recurrent autoencoder network architectures, deep learning - based reduced - order models have been recently shown to be effective while performing several orders of magnitude faster than full - order simulations. however, these models encounter significant challenges outside the training data, limiting their effectiveness for active control and optimization tasks. in this study, we aim to improve the extrapolation capability by modifying network architecture and integrating coupled space - time physics as an implicit bias. reduced - order models via deep learning generally employ decoupling in spatial and temporal dimensions, which can introduce modeling and approximation errors. to alleviate these errors, we propose a novel technique for learning coupled spatial - temporal correlation using a 3d convolution network. we assess the proposed technique against a standard encoder - propagator - decoder model and demonstrate a superior extrapolation performance. to demonstrate the effectiveness of 3d convolution network, we consider a benchmark problem of the flow past a circular cylinder at laminar flow conditions and use the spatio - temporal snapshots from the full - order simulations. our proposed 3d convolution architecture accurately captures the velocity and pressure fields for varying reynolds numbers. compared to the standard encoder - propagator - decoder network, the spatio - temporal - based 3d convolution network improves the prediction range of reynolds numbers outside of the training data.
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arxiv:2211.00307
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the long term time evolution of tidal dwarf satellite galaxies with two different initial densities orbiting a host galaxy that resembles the milky way has been studied using a large set of newtonian n - body simulations. from the simulations two maps of the orbital conditions that lead to quasi - equilibrium objects were constructed. it has been found that several orbits of the satellites allow for the existence, for about 1 gyr or more, of out - of - equilibrium bodies with high apparent mass - to - light ratios. within this framework the satellites in the quasi - stable phase reproduce the observed satellite properties for about 16 % of the orbit for high density progenitors, and for about 66 % for progenitors with lower densities an additional simulation for a single satellite with initial mass of 10 ^ 7 msun and plummer radius of 0. 15 kpc leads to remnants in the quasi - equilibrium phase that simultaneously reproduce remarkably well the observational quantities of the ufdgs of the milky way. this satellite in the quasi - stable phase reproduces the observed satellite properties for about 42 % of the orbit. the results suggest that a fraction of the observed satellites could plausibly be galaxies without dark matter that have true m / l ratios much lower than those measured. the inflated m / l ratios arise because they are observed at the right time, along the right orbit and during the quasi - equilibrium phase of their evolution. this is a viable explanation for the high m / l ratios observed in all satellites as long as the satellites are preferentially on certain orbits and are observed at certain times. this could arise within the tdg scenario if all satellites are created at the same time along a few specific orbits that are particularly susceptible to the quasi - equilibrium phase.
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arxiv:1205.5029
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in this paper we prove that the focusing, $ d $ - dimensional mass critical nonlinear schr { \ " o } dinger initial value problem is globally well - posed and scattering for $ u _ { 0 } \ in l ^ { 2 } ( \ mathbf { r } ^ { d } ) $, $ \ | u _ { 0 } \ | _ { l ^ { 2 } ( \ mathbf { r } ^ { d } ) } < \ | q \ | _ { l ^ { 2 } ( \ mathbf { r } ^ { d } ) } $, where $ q $ is the ground state, and $ d \ geq 1 $. we first establish an interaction morawetz estimate that is positive definite when $ \ | u _ { 0 } \ | _ { l ^ { 2 } ( \ mathbf { r } ^ { d } ) } < \ | q \ | _ { l ^ { 2 } ( \ mathbf { r } ^ { d } ) } $, and has the appropriate scaling. next, we will prove a frequency localized interaction morawetz estimate similar to the estimates made in \ cite { d2 }, \ cite { d3 }, \ cite { d4 }. see also \ cite { ckstt4 } for the energy critical case. since we are considering an $ l ^ { 2 } $ - critical initial value problem we will localize to low frequencies.
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arxiv:1104.1114
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recent advances in vision transformers ( vits ) have come with a voracious appetite for computing power, high - lighting the urgent need to develop efficient training methods for vits. progressive learning, a training scheme where the model capacity grows progressively during training, has started showing its ability in efficient training. in this paper, we take a practical step towards efficient training of vits by customizing and automating progressive learning. first, we develop a strong manual baseline for progressive learning of vits, by introducing momentum growth ( mogrow ) to bridge the gap brought by model growth. then, we propose automated progressive learning ( autoprog ), an efficient training scheme that aims to achieve lossless acceleration by automatically increasing the training overload on - the - fly ; this is achieved by adaptively deciding whether, where and how much should the model grow during progressive learning. specifically, we first relax the optimization of the growth schedule to sub - network architecture optimization problem, then propose one - shot estimation of the sub - network performance via an elastic supernet. the searching overhead is reduced to minimal by recycling the parameters of the supernet. extensive experiments of efficient training on imagenet with two representative vit models, deit and volo, demonstrate that autoprog can accelerate vits training by up to 85. 1 % with no performance drop. code : https : / / github. com / changlin31 / autoprog
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arxiv:2203.14509
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machine learning - as - a - service ( mlaas ) has become a widespread paradigm, making even the most complex machine learning models available for clients via e. g. a pay - per - query principle. this allows users to avoid time - consuming processes of data collection, hyperparameter tuning, and model training. however, by giving their customers access to the ( predictions of their ) models, mlaas providers endanger their intellectual property, such as sensitive training data, optimised hyperparameters, or learned model parameters. adversaries can create a copy of the model with ( almost ) identical behavior using the the prediction labels only. while many variants of this attack have been described, only scattered defence strategies have been proposed, addressing isolated threats. this raises the necessity for a thorough systematisation of the field of model stealing, to arrive at a comprehensive understanding why these attacks are successful, and how they could be holistically defended against. we address this by categorising and comparing model stealing attacks, assessing their performance, and exploring corresponding defence techniques in different settings. we propose a taxonomy for attack and defence approaches, and provide guidelines on how to select the right attack or defence strategy based on the goal and available resources. finally, we analyse which defences are rendered less effective by current attack strategies.
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arxiv:2206.08451
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the disturbance storm time ( dst ) index has been widely used as a proxy for the ring current intensity, and therefore as a measure of geomagnetic activity. it is derived by measurements from four ground magnetometers in the geomagnetic equatorial regions. we present a new model for predicting $ dst $ with a lead time between 1 and 6 hours. the model is first developed using a gated recurrent unit ( gru ) network that is trained using solar wind parameters. the uncertainty of the $ dst $ model is then estimated by using the accrue method [ camporeale et al. 2021 ]. finally, a multi - fidelity boosting method is developed in order to enhance the accuracy of the model and reduce its associated uncertainty. it is shown that the developed model can predict $ dst $ 6 hours ahead with a root - mean - square - error ( rmse ) of 13. 54 $ \ mathrm { nt } $. this is significantly better than the persistence model and a simple gru model.
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arxiv:2209.12571
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}. $ finally, we obtain a characterization of finitely generated virtually regular modules over the ring of integers.
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arxiv:2406.11222
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this paper presents results of a european big data hackathon entry to facilitate data analysis and visualization of patterns in provided and external datasets about european jobs and skills mismatch and labour market in general. the main contributions of this work are : the development of a method to represent the complex labour market internal structure from the perspective of occupations sharing skills ; developing and presenting the prototype, together with an extended description of constructing a graph and related necessary data processing. since labour market is not an isolated phenomenon and is constantly impacted with external trends and interventions, the presented tool is designed to enable adding extra layers of external information : what is the impact of a megatrend or an intervention to the labour market? which parts of labour market of what country is most vulnerable to approaching megatrend or planned intervention? a case of analysing the labour market together with the megatrend of automation and computerization of jobs is presented. the source code of the prototype is released as open source for better repeat - ability.
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arxiv:1708.08262
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the mechanism by which a threshold may capture a resonance is examined. it involves a threshold cusp interfering constructively with either or both ( i ) a resonance produced via confinement, ( ii ) attractive t - and u - channel exchanges. the fo ( 980 ), x ( 3872 ) and z ( 4430 ) are studied in detail. the fo ( 980 ) provides a valuable model of the locking mechanism. the x ( 3872 ) is too narrow to be fitted by a cusp, and requires either a resonance or virtual state. the z ( 4430 ) can be fitted as a resonance but also can be fitted successfully by a cusp with no nearby resonant pole.
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arxiv:0802.0934
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we study the two - dimensional rydberg atom array in an optical cavity with help of the meanfield theory and the large - scale quantum monte carlo simulations. the strong dipole - dipole interactions between rydberg atoms can make the system exhibit the crystal structure, and the coupling between two - level atom and cavity photon mode can result in the formation of the polariton. the interplay between them provides a rich quantum phase diagram including the mott, solid - 1 / 2, superradiant and superradiant solid phases. as the two - order co - existed phase, the superradiant solid phase breaks both translational and u ( 1 ) symmetries. based on both numerical and analytic results, we found the region of superradiant solid is much larger than one dimensional case, so that it can be more easily observed in the experiment. finally, we discuss how the energy gap of the rydberg atom can affect the type of the quantum phase transition and the number of triple points.
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arxiv:2204.08800
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to cope with the unprecedented surge in demand for data computing for the applications, the promising concept of multi - access edge computing ( mec ) has been proposed to enable the network edges to provide closer data processing for mobile devices ( mds ). since enormous workloads need to be migrated, and mds always remain resource - constrained, data offloading from devices to the mec server will inevitably require more efficient transmission designs. the integration of nonorthogonal multiple access ( noma ) technique with mec has been shown to provide applications with lower latency and higher energy efficiency. however, existing designs of this type have mainly focused on the transmission technique, which is still insufficient. to further advance offloading performance, in this work, we propose an application - driven noma enabled computation offloading scheme by exploring the characteristics of applications, where the common data of the application is offloaded through multi - device cooperation. under the premise of successfully offloading the common data, we formulate the problem as the maximization of individual offloading throughput, where the time allocation and power control are jointly optimized. by using the successive convex approximation ( sca ) method, the formulated problem can be iteratively solved. simulation results demonstrate the convergence of our method and the effectiveness of the proposed scheme.
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arxiv:2008.05510
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eclipse time variations have been detected in a number of post common envelope binary systems consisting of a subdwarf b star or white dwarf primary star and cool m type or brown dwarf secondary. in this paper we consider circumbinary hypotheses of two sdb systems, hs 0705 + 6700 ( also known as v470 cam ) and nsvs 14256825 and one white dwarf system, nn ser. in addition, and for comparison purposes, we investigate the eclipse time variations of the w uma system nsvs 01286630 with its stellar circumbinary companion. all four systems have claims of circumbinary objects with computed physical and orbital parameters. we report 108 new observations of minima for these four eclipsing systems observed between 2017 may and 2019 september and combining these with all published data, we investigate how well the published circumbinary object hypotheses fit with our new data. our new data has shown departure from early predictions for three of the four systems, but it is premature to conclude that these results rule out the presence of circumbinary objects. there is also the possibility ( but with no observational proof so far ) of detecting close - in transiting circumbinary objects around these systems but these are likely to have periods of days rather than years.
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arxiv:1911.00125
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due to the homophily assumption in graph convolution networks ( gnns ), a common consensus in the graph node classification task is that gnns perform well on homophilic graphs but may fail on heterophilic graphs with many inter - class edges. however, the previous inter - class edges perspective and related homo - ratio metrics cannot well explain the gnns performance under some heterophilic datasets, which implies that not all the inter - class edges are harmful to gnns. in this work, we propose a new metric based on von neumann entropy to re - examine the heterophily problem of gnns and investigate the feature aggregation of inter - class edges from an entire neighbor identifiable perspective. moreover, we propose a simple yet effective conv - agnostic gnn framework ( cagnns ) to enhance the performance of most gnns on heterophily datasets by learning the neighbor effect for each node. specifically, we first decouple the feature of each node into the discriminative feature for downstream tasks and the aggregation feature for graph convolution. then, we propose a shared mixer module to adaptively evaluate the neighbor effect of each node to incorporate the neighbor information. the proposed framework can be regarded as a plug - in component and is compatible with most gnns. the experimental results over nine well - known benchmark datasets indicate that our framework can significantly improve performance, especially for the heterophily graphs. the average performance gain is 9. 81 %, 25. 81 %, and 20. 61 % compared with gin, gat, and gcn, respectively. extensive ablation studies and robustness analysis further verify the effectiveness, robustness, and interpretability of our framework. code is available at https : / / github. com / jc - 202 / cagnn.
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arxiv:2203.11200
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in 2009, chazal et al. introduced $ \ epsilon $ - interleavings of persistence modules. $ \ epsilon $ - interleavings induce a pseudometric $ d _ i $ on ( isomorphism classes of ) persistence modules, the interleaving distance. the definitions of $ \ epsilon $ - interleavings and $ d _ i $ generalize readily to multidimensional persistence modules. in this paper, we develop the theory of multidimensional interleavings, with a view towards applications to topological data analysis. we present four main results. first, we show that on 1 - d persistence modules, $ d _ i $ is equal to the bottleneck distance $ d _ b $. this result, which first appeared in an earlier preprint of this paper, has since appeared in several other places, and is now known as the isometry theorem. second, we present a characterization of the $ \ epsilon $ - interleaving relation on multidimensional persistence modules. this expresses transparently the sense in which two $ \ epsilon $ - interleaved modules are algebraically similar. third, using this characterization, we show that when we define our persistence modules over a prime field, $ d _ i $ satisfies a universality property. this universality result is the central result of the paper. it says that $ d _ i $ satisfies a stability property generalizing one which $ d _ b $ is known to satisfy, and that in addition, if $ d $ is any other pseudometric on multidimensional persistence modules satisfying the same stability property, then $ d \ leq d _ i $. we also show that a variant of this universality result holds for $ d _ b $, over arbitrary fields. finally, we show that $ d _ i $ restricts to a metric on isomorphism classes of finitely presented multidimensional persistence modules.
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arxiv:1106.5305
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we introduce a novel method to perform linear optical random projections without the need for holography. our method consists of a computationally trivial combination of multiple intensity measurements to mitigate the information loss usually associated with the absolute - square non - linearity imposed by optical intensity measurements. both experimental and numerical findings demonstrate that the resulting matrix consists of real - valued, independent, and identically distributed ( i. i. d. ) gaussian random entries. our optical setup is simple and robust, as it does not require interference between two beams. we demonstrate the practical applicability of our method by performing dimensionality reduction on high - dimensional data, a common task in randomized numerical linear algebra with relevant applications in machine learning.
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arxiv:2305.12988
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we present the measurement of the hubble constant, $ h _ 0 $, with three strong gravitational lens systems. we describe a blind analysis of both pg1115 + 080 and he0435 - 1223 as well as an extension of our previous analysis of rxj1131 - 1231. for each lens, we combine new adaptive optics ( ao ) imaging from the keck telescope, obtained as part of the sharp ao effort, with hubble space telescope ( hst ) imaging, velocity dispersion measurements, and a description of the line - of - sight mass distribution to build an accurate and precise lens mass model. this mass model is then combined with the cosmograil measured time delays in these systems to determine $ h _ { 0 } $. we do both an ao - only and an ao + hst analysis of the systems and find that ao and hst results are consistent. after unblinding, the ao - only analysis gives $ h _ { 0 } = 82. 8 ^ { + 9. 4 } _ { - 8. 3 } ~ \ rm km \, s ^ { - 1 } \, mpc ^ { - 1 } $ for pg1115 + 080, $ h _ { 0 } = 70. 1 ^ { + 5. 3 } _ { - 4. 5 } ~ \ rm km \, s ^ { - 1 } \, mpc ^ { - 1 } $ for he0435 - 1223, and $ h _ { 0 } = 77. 0 ^ { + 4. 0 } _ { - 4. 6 } ~ \ rm km \, s ^ { - 1 } \, mpc ^ { - 1 } $ for rxj1131 - 1231. the joint ao - only result for the three lenses is $ h _ { 0 } = 75. 6 ^ { + 3. 2 } _ { - 3. 3 } ~ \ rm km \, s ^ { - 1 } \, mpc ^ { - 1 } $. the joint result of the ao + hst analysis for the three lenses is $ h _ { 0 } = 76. 8 ^ { + 2. 6 } _ { - 2. 6 } ~ \ rm km \, s ^ { - 1 } \, mpc ^ { - 1 } $. all of the above results assume a flat $ \ lambda $ cold dark matter cosmology with a uniform prior on $ \ omega _ {
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arxiv:1907.02533
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let $ f $ be a local non - archimedean field and $ e $ a finite galois extension of $ f $, with galois group $ g $. if $ \ rho $ is a representation of $ g $ on a complex vector space $ v $, we may compose it with any tensor operation $ r $ on $ v $, and get another representation $ r \ circ \ rho $. we study the relation between the swan exponents $ \ mathrm { sw } ( \ rho ) $ and $ \ mathrm { sw } ( r \ circ \ rho ) $, with a particular attention to the cases where $ r $ is symmetric square or exterior square. indeed those cases intervene in the local langlands correspondence for split classical groups over $ f $, via the formal degree conjecture, and we present some applications of our work to the explicit description of the langlands parameter of simple cuspidal representations. for irreducible $ \ rho $ our main results determine $ \ mathrm { sw } ( \ mathrm { sym } ^ { 2 } \ rho ) $ and $ \ mathrm { sw } ( \ wedge ^ { 2 } \ rho ) $ from $ \ mathrm { sw } ( \ rho ) $ when the residue characteristic $ p $ of $ f $ is odd, and bound them in terms of $ \ mathrm { sw } ( \ rho ) $ when $ p $ is $ 2 $. in that case where $ p $ is $ 2 $ we conjecture stronger bounds, for which we provide evidence.
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arxiv:2307.15248
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resonant hadronic systems often exhibit a complicated decay pattern in which three - body dynamics play a relevant or even dominant role. in this work we focus on the $ a _ 1 ( 1260 ) $ resonance. for the first time, the pole position and branching ratios of a three - body resonance are calculated from lattice qcd using one -, two -, and three - meson interpolators and a three - body finite - volume formalism extended to spin and coupled channels. this marks a new milestone for ab - initio studies of ordinary resonances along with hybrid and exotic hadrons involving three - body dynamics.
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arxiv:2107.03973
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we have catalogued 196 filament oscillations from the gong $ h { \ alpha } $ network data during several months near the maximum of solar cycle 24 ( january - june 2014 ). selected examples from the catalog are described in detail, along with our statistical analyses of all events. oscillations were classified according to their velocity amplitude : 106 small - amplitude oscillations ( saos ), with velocities $ < 10 \ mathrm { \, km \ ; s ^ { - 1 } } $, and 90 large - amplitude oscillations ( laos ), with velocities $ > 10 \ mathrm { \, km \ ; s ^ { - 1 } } $. both saos and laos are common, with one event of each class every two days on the visible side of the sun. for nearly half of the events we identified their apparent trigger. the period distribution has a mean value of 58 $ \ pm $ 15 min for both types of oscillations. the distribution of the damping time per period peaks at $ \ tau / p = 1. 75 $ and $ 1. 25 $ for saos and laos respectively. we confirmed that lao damping rates depend nonlinearly on the oscillation velocity. the angle between the direction of motion and the filament spine has a distribution centered at $ 27 ^ \ circ $ for all filament types. this angle agrees with the observed direction of filament - channel magnetic fields, indicating that most of the catalogued events are longitudinal ( i. e., undergo field - aligned motions ). we applied seismology to determine the average radius of curvature in the magnetic dips, $ r \ approx89 $ mm, and the average minimum magnetic - field strength, $ b \ approx16 $ g. the catalog is available to the community online, and is intended to be expanded to cover at least 1 solar cycle.
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arxiv:1804.03743
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we study and classify free actions of compact quantum groups on unital c * - algebras in terms of generalized factor systems. moreover, we use these factor systems to show that all finite coverings of irrational rotation c * - algebras are cleft.
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arxiv:1701.05895
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we present { \ mu } split, a dedicated approach for trained image decomposition in the context of fluorescence microscopy images. we find that best results using regular deep architectures are achieved when large image patches are used during training, making memory consumption the limiting factor to further improving performance. we therefore introduce lateral contextualization ( lc ), a novel meta - architecture that enables the memory efficient incorporation of large image - context, which we observe is a key ingredient to solving the image decomposition task at hand. we integrate lc with u - nets, hierarchical aes, and hierarchical vaes, for which we formulate a modified elbo loss. additionally, lc enables training deeper hierarchical models than otherwise possible and, interestingly, helps to reduce tiling artefacts that are inherently impossible to avoid when using tiled vae predictions. we apply { \ mu } split to five decomposition tasks, one on a synthetic dataset, four others derived from real microscopy data. our method consistently achieves best results ( average improvements to the best baseline of 2. 25 db psnr ), while simultaneously requiring considerably less gpu memory. our code and datasets can be found at https : / / github. com / juglab / usplit.
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arxiv:2211.12872
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xte j1810 - 189 underwent an outburst in 2008, and was observed over $ \ sim 100 $ d by rxte. performing a time - resolved spectral analysis on the photospheric radius expansion burst detected on 2008 may 4, we obtain the source distance in the range of 3. 5 - - 8. 7 kpc for the first time. during its outburst, xte j1810 - 189 did not enter into the high / soft state, and both the soft and hard colours decreased with decreasing flux. the fractional rms remained at high values ( $ \ sim 30 $ per cent ). the rxte / pca spectra for 3 - 25 kev can be described by an absorbed power - law component with an additional gaussian component, and the derived photon index $ \ gamma $ increased from $ 1. 84 \ pm0. 01 $ to $ 2. 25 \ pm0. 04 $ when the unabsorbed x - ray luminosity in 3 - 25 kev dropped from $ 4 \ times10 ^ { 36 } $ ergs s $ ^ { - 1 } $ to $ 6 \ times10 ^ { 35 } $ ergs s $ ^ { - 1 } $. the relatively high flux, dense observations and broadband spectra allow us to provide strong evidence that the softening behaviour detected in the outburst of xte j1810 - 189 originates from the evolution of non - thermal component rather than the thermal component ( i. e. neutron star surface emission ).
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arxiv:1511.07671
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in this article, we study the hausdor dimension of weakly conformal ifs ' s shrinking targets with possible overlaps, provided the conformality dimension of the systems and the dimension of the attractor are equal. those results extends the works of hill - velani as well as the results obtained in [ 6 ] for self - similar ifs ' s.
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arxiv:2207.08458
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we investigate the evolutionary dynamics in directed and / or weighted networks. we study the fixation probability of a mutant in finite populations in stochastic voter - type dynamics for several update rules. the fixation probability is defined as the probability of a newly introduced mutant in a wild - type population taking over the entire population. in contrast to the case of undirected and unweighted networks, the fixation probability of a mutant in directed networks is characterized not only by the degree of the node that the mutant initially invades but by the global structure of networks. consequently, the gross connectivity of networks such as small - world property or modularity has a major impact on the fixation probability.
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arxiv:0812.1075
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mergers of neutron stars ( ns ) and white dwarfs ( wd ) may give rise to observable explosive transient events. we use 3d hydrodynamical ( sph ) simulations, as well as 2d hydrodynamical - thermonuclear simulations ( using the flash amr code ) to model the disruption of co - wds by nss, which produce faint transient events. we post - process the simulations using a large nuclear network and make use of the supernu radiation - transfer code to predict the observational signatures and detailed properties of these transients. we calculate the light - curves ( lc ) and spectra for five models of ns - co - wd mergers. the small yields of ni56 ( few x 0. 001msun ) results in faint, rapidly - evolving reddened transients ( rrts ) with b ( r ) - peak magnitudes of ~ - 12 ( - 13 ) to ~ - 13 ( - 15 ), much shorter and fainter than both regular and faint / peculiar type - ia sne. we show that the spectra of rrts share some similarities with rapidly - evolving transients such as sn2010x, though rrts are significantly fainter, especially in the i / r bands, and show far stronger si lines. we estimate that the upcoming large synoptic survey telescope could detect rrts at a rate of ~ 10 - 70 yr ^ - 1, through observations in the r / i bands.
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arxiv:1908.10866
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[ abridged ] in galactic nuclei with sufficiently short relaxation times, binary supermassive black holes can evolve beyond their stalling radii via continued interaction with stars. we study this " collisional " evolutionary regime using both fully self - consistent n - body integrations and approximate fokker - planck models. the n - body integrations employ particle numbers up to 0. 26m and a direct - summation potential solver ; close interactions involving the binary are treated using a new implementation of the mikkola - aarseth chain regularization algorithm. even at these large values of n, two - body scattering occurs at high enough rates in the simulations that they can not be simply scaled to the large - n regime of real galaxies. the fokker - planck model is used to bridge this gap ; it includes, for the first time, binary - induced changes in the stellar density and potential. the fokker - planck model is shown to accurately reproduce the results of the n - body integrations, and is then extended to the much larger n regime of real galaxies. analytic expressions are derived that accurately reproduce the time dependence of the binary semi - major axis as predicted by the fokker - planck model. gravitational wave coalescence is shown to occur in < 10 gyr in nuclei with velocity dispersions below about 80 km / s. formation of a core results from a competition between ejection of stars by the binary and re - supply of depleted orbits via two - body scattering. mass deficits as large as ~ 4 times the binary mass are produced before coalescence. after the two black holes coalesce, a bahcall - wolf cusp appears around the single hole in one relaxation time, resulting in a nuclear density profile consisting of a flat core with an inner, compact cluster, similar to what is observed at the centers of low - luminosity spheroids.
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arxiv:0705.2745
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we report the discovery of a young stellar bridge, that forms a continuous connection between the magellanic clouds. this finding is based on number density maps for stellar populations found in data gathered by ogle - iv, that fully cover over 270 deg ^ 2 of the sky in the magellanic bridge area. this is the most extensive optical survey of this region up to date. we find that the young population is present mainly in the western half of the mbr, which, together with the newly discovered young population in the eastern bridge, form a continuous stream of stars connecting both galaxies along dec ~ - 73. 5 deg. the young population distribution is clumped, with one of the major densities close to the smc, and the other, fairly isolated and located approximately mid - way between the clouds, which we call the ogle island. these overdensities are well matched by hi surface density contours, although the newly found young population in the eastern bridge is offset by ~ 2 deg north from the highest hi density contour. we observe a continuity of red clump stars between the magellanic clouds, which represent an intermediate - age population. red clump stars are present mainly in the southern and central parts of the magellanic bridge, below its gaseous part, and their presence is reflected by a strong deviation from the radial density profiles of the two galaxies. this may indicate either a tidal stream of stars, or that the stellar halos of the two galaxies overlap. on the other hand, we do not observe such an overlap within an intermediate - age population represented by the top of the red giant branch and the asymptotic giant branch stars. we also see only minor mixing of the old populations of the clouds in the southern part of the bridge, represented by the lowest part of the red giant branch.
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arxiv:1405.7364
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non - local self - similarity is well - known to be an effective prior for the image denoising problem. however, little work has been done to incorporate it in convolutional neural networks, which surpass non - local model - based methods despite only exploiting local information. in this paper, we propose a novel end - to - end trainable neural network architecture employing layers based on graph convolution operations, thereby creating neurons with non - local receptive fields. the graph convolution operation generalizes the classic convolution to arbitrary graphs. in this work, the graph is dynamically computed from similarities among the hidden features of the network, so that the powerful representation learning capabilities of the network are exploited to uncover self - similar patterns. we introduce a lightweight edge - conditioned convolution which addresses vanishing gradient and over - parameterization issues of this particular graph convolution. extensive experiments show state - of - the - art performance with improved qualitative and quantitative results on both synthetic gaussian noise and real noise.
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arxiv:1907.08448
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in this paper a family of non - singular cylindrical perfect fluid cosmologies is derived. the equation of state corresponds to a stiff fluid. the family depends on two independent functions under very simple conditions. a sufficient condition for geodesic completeness is provided.
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arxiv:gr-qc/0402119
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in cryptography, block ciphers are the most fundamental elements in many symmetric - key encryption systems. the cipher block chaining, denoted cbc, presents one of the most famous mode of operation that uses a block cipher to provide confidentiality or authenticity. in this research work, we intend to summarize our results that have been detailed in our previous series of articles. the goal of this series has been to obtain a complete topological study of the cbc block cipher mode of operation after proving his chaotic behavior according to the reputed definition of devaney.
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arxiv:1708.03243
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the spatial modes of light, carrying a quantized amount of orbital angular momentum ( oam ), is one of the excellent candidates that provides access to high - dimensional quantum states, which essentially makes it promising towards building high - dimensional quantum networks. in this paper, we report the storage and retrieval of photonic qubits encoded with oam state in the cold atomic ensemble, achieving an average conditional fidelity above 98 % and retrieval efficiency around 65 %. the photonic oam qubits are encoded with weak coherent states at the single - photon level and the memory is based on electromagnetically induced transparency in an elongated cold rubidium atomic ensemble. our work constitutes an efficient node that is needed towards high dimensional and large scale quantum networks.
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arxiv:2012.12451
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web - based test automation heavily relies on accurately finding web elements. traditional methods compare attributes but don ' t grasp the context and meaning of elements and words. the emergence of large language models ( llms ) like gpt - 4, which can show human - like reasoning abilities on some tasks, offers new opportunities for software engineering and web element localization. this paper introduces and evaluates von similo llm, an enhanced web element localization approach. using an llm, it selects the most likely web element from the top - ranked ones identified by the existing von similo method, ideally aiming to get closer to human - like selection accuracy. an experimental study was conducted using 804 web element pairs from 48 real - world web applications. we measured the number of correctly identified elements as well as the execution times, comparing the effectiveness and efficiency of von similo llm against the baseline algorithm. in addition, motivations from the llm were recorded and analyzed for all instances where the original approach failed to find the right web element. von similo llm demonstrated improved performance, reducing failed localizations from 70 to 39 ( out of 804 ), a 44 percent reduction. despite its slower execution time and additional costs of using the gpt - 4 model, the llms human - like reasoning showed promise in enhancing web element localization. llm technology can enhance web element identification in gui test automation, reducing false positives and potentially lowering maintenance costs. however, further research is necessary to fully understand llms capabilities, limitations, and practical use in gui testing.
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arxiv:2310.02046
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we study the characteristics of quark matter under the influence of a background magnetic field with anomalous magnetic moment ( amm ) of quarks at finite temperature and quark chemical potential in the framework of polyakov loop extended nambu jona - lasinio ( pnjl ) model. in presence of a magnetic field, the speed of sound and isothermal compressibility become anisotropic with respect to the direction of the background magnetic field, splitting into parallel and perpendicular directions with respect to the magnetic field. though the qualitative nature of parallel and perpendicular components of squared speed of sound appear similar, they differ in magnitude at lower values of temperature. the parallel and perpendicular components of isothermal compressibility decrease with increasing temperature, indicating a trend towards increased incompressible strongly interacting matter. on inclusion of the amm of quarks, the perpendicular component of isothermal compressibility becomes greater than the parallel component. additionally, we investigate the quark number susceptibility normalized by its value at zero magnetic field, which may indicate the presence of magnetic fields in the system.
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arxiv:2408.04398
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three - dimensional simulations for the merger of binary neutron stars ( bnss ) are performed in the framework of full general relativity. we pay particular attention to the black hole ( bh ) formation case and to the resulting mass of the surrounding disk for exploring possibility for formation of the central engine of short - duration gamma - ray bursts. hybrid equations of state ( eoss ) are adopted mimicking realistic, stiff nuclear eoss, for which the maximum allowed gravitational mass of cold and spherical neutron stars ( nss ), m _ sph, is larger than 2m _ sun. for the simulations, we focus on bnss of the adm mass m > 2. 6m _ sun. for m > m _ thr, the merger results in prompt formation of a bh irrespective of the mass ratio q _ m with 0. 65 < q _ m < 1. the value of m _ thr is approximately written as 1. 3 - 1. 35m _ sph for the chosen eoss. for the bh formation case, we evolve the spacetime using a bh excision technique and determine the mass of a quasistationary disk surrounding the bh. the disk mass steeply increases with decreasing the value of q _ m for given adm mass and eos. for m < m _ thr, the outcome is a hypermassive neutron star ( hmns ) of a large ellipticity. if the hmns collapses to a bh after the longterm angular momentum transport, the disk mass may be > 0. 01m _ sun. gravitational waves ( gws ) are computed in terms of a gauge - invariant wave extraction technique. in the formation of the hmns, quasiperiodic gws of frequency ( 3 - 3. 5khz ) are emitted. the effective amplitude of gws can be > 5x10 ^ { - 21 } at a distance of 50 mpc. for the bh formation case, the bh excision technique enables a longterm computation and extraction of ring - down gws associated with a bh quasinormal mode. it is found that the frequency and amplitude are 6. 5 - 7khz and 10 ^ { - 22 } at a distance of 50mpc for m = 2. 7 - 2. 9m _ sun.
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arxiv:astro-ph/0603145
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since the super - kamiokande ( sk ) neutrino experiment in japan added gadolinium sulphate octahydrate ( gd ) to the pure water in its detector, it has entered a new era in supernova neutrino detection. the addition of gd makes it possible to tag neutrons from inverse beta decay ( ibd ) interactions of electron antineutrinos with free protons in the water. this has led to significant improvement in the experiment ' s sensitivity to low - energy electron antineutrinos, which is key in the observation of supernova neutrinos. super - kamiokande gadolinium ( sk - gd ) has the potential to make the first observation of the diffuse supernova neutrino background ( dsnb ) and pre - supernova ( presn ) neutrinos, and can improve the pointing capability of sk in the event of a core - collapse supernova ( ccsn ) explosion. we present the latest results and prospects for supernova neutrino detection with sk - gd.
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arxiv:2404.00716
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we consider the following distributed consensus problem : each node in a complete communication network of size $ n $ initially holds an \ emph { opinion }, which is chosen arbitrarily from a finite set $ \ sigma $. the system must converge toward a consensus state in which all, or almost all nodes, hold the same opinion. moreover, this opinion should be \ emph { valid }, i. e., it should be one among those initially present in the system. this condition should be met even in the presence of an adaptive, malicious adversary who can modify the opinions of a bounded number of nodes in every round. we consider the \ emph { 3 - majority dynamics } : at every round, every node pulls the opinion from three random neighbors and sets his new opinion to the majority one ( ties are broken arbitrarily ). let $ k $ be the number of valid opinions. we show that, if $ k \ leqslant n ^ { \ alpha } $, where $ \ alpha $ is a suitable positive constant, the 3 - majority dynamics converges in time polynomial in $ k $ and $ \ log n $ with high probability even in the presence of an adversary who can affect up to $ o ( \ sqrt { n } ) $ nodes at each round. previously, the convergence of the 3 - majority protocol was known for $ | \ sigma | = 2 $ only, with an argument that is robust to adversarial errors. on the other hand, no anonymous, uniform - gossip protocol that is robust to adversarial errors was known for $ | \ sigma | > 2 $.
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arxiv:1508.06782
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the context caching technique is employed to accelerate the multimodal large language model ( mllm ) inference by prevailing serving platforms currently. however, this approach merely reuses the key - value ( kv ) cache of the initial sequence of prompt, resulting in full kv cache recomputation even if the prefix differs slightly. this becomes particularly inefficient in the context of interleaved text and images, as well as multimodal retrieval - augmented generation. this paper proposes position - independent caching as a more effective approach for multimodal information management. we have designed and implemented a caching system, named mpic, to address both system - level and algorithm - level challenges. mpic stores the kv cache on local or remote disks when receiving multimodal data, and calculates and loads the kv cache in parallel during inference. to mitigate accuracy degradation, we have incorporated integrated reuse and recompute mechanisms within the system. the experimental results demonstrate that mpic can achieve up to 54 % reduction in response time compared to existing context caching systems, while maintaining negligible or no accuracy loss.
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arxiv:2502.01960
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we present new jwst nirspec integral field unit ( ifu ) g395h / f290lp observations of a merging galaxy system at $ z = 7. 88 $, part of a2744 - z7p9, the most distant protocluster to date. the ifu cube reveals [ oiii ] emissions in two previously known galaxies ( zd3 and zd6 ) and a newly identified galaxy, zd12, at $ z _ { \ rm spec } = 7. 8762 $. one of the detected \ oiii - emitting regions has a detection of the auroral [ oiii ] 4363, line, allowing us to derive a direct metallicity of $ \ log $ ( o / h ) $ + 12 = 7. 4 \ pm0. 2 $, while metallicities in other regions are measured using strong line calibration methods. we find large deviations within the measured metallicity ( $ \ delta \ log { \ rm ( o / h ) } \ sim1 $ ), which suggests a fast chemical enrichment from intense star formation and merger - driven growth, as expected in early galaxies. our analysis shows that metal - poor regions could easily be outshone by more enriched regions, posing a challenge for spectroscopic analysis based on integrated light ( i. e., nirspec msa ) against identifying metal - free star formation in the early universe. nircam imaging reveals seven uv - bright clumps in zd12, in the range of stellar mass $ \ log m _ * / m _ \ odot \ sim7. 6 $ - - 8. 9. four of them are unresolved ( $ < 100 $ pc ) and intensely star - forming ( $ > 30 m _ \ odot { \ rm yr ^ { - 1 } kpc ^ { - 2 } } $ ), likely contributing to the scatter in metallicity by producing an ideal environment for rapid chemical cycles. lastly, we revisit the nature of the host protocluster by including new member galaxies identified here and in the literature, and obtain local overdensity factor $ \ delta = 44 _ { - 31 } ^ { + 89 } $, total halo mass $ m _ { \ rm h } = 5. 8 _ { - 0. 3 } ^ { + 0. 2 } \ times10 ^ { 11 } \, m _ \ odot $, and a formal velocity
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arxiv:2501.11879
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we report rotation periods, variability characteristics, gyrochronological ages for ~ 950 of the kepler object of interest host stars. we find a wide dispersion in the amplitude of the photometric variability as a function of rotation, likely indicating differences in the spot distribution among stars. we use these rotation periods in combination with published spectroscopic measurements of vsini and stellar parameters to derive the stellar inclination in the line - of - sight, and find a number of systems with possible spin - orbit misalignment. we additionally find several systems with close - in planet candidates whose stellar rotation periods are equal to or twice the planetary orbital period, indicative of possible tidal interactions between these planets and their parent stars. if these systems survive validation to become confirmed planets, they will provide important clues to the evolutionary history of these systems.
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arxiv:1309.2159
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large language models ( llms ), such as gpt - 4, gemini 1. 5, claude 3. 5 sonnet, and llama3, have demonstrated significant advancements in various nlp tasks since the release of chatgpt in 2022. despite their success, fine - tuning and deploying llms remain computationally expensive, especially in resource - constrained environments. in this paper, we proposed vieteduframe, a framework specifically designed to apply llms to educational management tasks in vietnamese institutions. our key contribution includes the development of a tailored dataset, derived from student education documents at hanoi vnu, which addresses the unique challenges faced by educational systems with limited resources. through extensive experiments, we show that our approach outperforms existing methods in terms of accuracy and efficiency, offering a promising solution for improving educational management in under - resourced environments. while our framework leverages synthetic data to supplement real - world examples, we discuss potential limitations regarding broader applicability and robustness in future implementations.
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arxiv:2501.15022
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we present a framework based on catch2 to evaluate performance of openmp ' s target offload model via micro - benchmarks. the compilers supporting openmp ' s target offload model for heterogeneous architectures are currently undergoing rapid development. these developments influence performance of various complex applications in different ways. this framework can be employed to track the impact of compiler upgrades and compare their performance with the native programming models. we use the framework to benchmark performance of a few commonly used operations on leadership class supercomputers such as perlmutter at national energy research scientific computing ( nersc ) center and frontier at oak ridge leadership computing facility ( olcf ). such a framework will be useful for compiler developers to gain insights into the overall impact of many small changes, as well as for users to decide which compilers and versions are expected to yield best performance for their applications.
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arxiv:2503.00408
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in recent years, the development of robotics and artificial intelligence ( ai ) systems has been nothing short of remarkable. as these systems continue to evolve, they are being utilized in increasingly complex and unstructured environments, such as autonomous driving, aerial robotics, and natural language processing. as a consequence, programming their behaviors manually or defining their behavior through reward functions ( as done in reinforcement learning ( rl ) ) has become exceedingly difficult. this is because such environments require a high degree of flexibility and adaptability, making it challenging to specify an optimal set of rules or reward signals that can account for all possible situations. in such environments, learning from an expert ' s behavior through imitation is often more appealing. this is where imitation learning ( il ) comes into play - a process where desired behavior is learned by imitating an expert ' s behavior, which is provided through demonstrations. this paper aims to provide an introduction to il and an overview of its underlying assumptions and approaches. it also offers a detailed description of recent advances and emerging areas of research in the field. additionally, the paper discusses how researchers have addressed common challenges associated with il and provides potential directions for future research. overall, the goal of the paper is to provide a comprehensive guide to the growing field of il in robotics and ai.
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arxiv:2309.02473
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social network based approaches to person recommendations are compared to interest based approaches with the help of an empirical study on a large german social networking platform. we assess and compare the performance of different basic variants of the two approaches by precision / recall based performance with respect to reproducing known friendship relations and by an empirical questionnaire based study. in accordance to expectation, the results show that interest based person recommenders are able to produce more novel recommendations while performing less well with respect to friendship reproduction. with respect to the user ' s assessment of recommendation quality all approaches perform comparably well, while combined social - interest - based variants are slightly ahead in performance. the overall results qualify those combined approaches as a good compromise.
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arxiv:1107.5654
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an idea of possible anomalous contribution of non - perturbative origin to the nucleon spin was examined by analysing data on spin asymmetries in polarized deep inelastic scattering of leptons on nucleons. the region of high bjorken x was explored. it was shown that experimental data available at present do not evidence for this effect.
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arxiv:hep-ph/9802266
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in this paper, a generalized fractional - order seir model is proposed, denoted by seiqrp model, which has a basic guiding significance for the prediction of the possible outbreak of infectious diseases like covid - 19 and other insect diseases in the future. firstly, some qualitative properties of the model are analyzed. the basic reproduction number $ r _ { 0 } $ is derived. when $ r _ { 0 } < 1 $, the disease - free equilibrium point is unique and locally asymptotically stable. when $ r _ { 0 } > 1 $, the endemic equilibrium point is also unique. furthermore, some conditions are established to ensure the local asymptotic stability of disease - free and endemic equilibrium points. the trend of covid - 19 spread in the united states is predicted. considering the influence of the individual behavior and government mitigation measurement, a modified seiqrp model is proposed, defined as seiqrpd model. according to the real data of the united states, it is found that our improved model has a better prediction ability for the epidemic trend in the next two weeks. hence, the epidemic trend of the united states in the next two weeks is investigated, and the peak of isolated cases are predicted. the modified seiqrp model successfully capture the development process of covid - 19, which provides an important reference for understanding the trend of the outbreak.
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arxiv:2004.12541
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we report the first experimental evidence for a metallic phase in fluid molecular oxygen. our electrical conductivity measurements of fluid oxygen under dynamic quasi - isentropic compression show that a non - metal / metal transition occurs at 3. 4 fold compression, 4500 k and 1. 2 mbar. we discuss the main features of the electrical conductivity dependence on density and temperature and give an interpretation of the nature of the electrical transport mechanisms in fluid oxygen at these extreme conditions.
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arxiv:cond-mat/0012295
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we propose an information - theoretic framework for matrix completion. the theory goes beyond the low - rank structure and applies to general matrices of " low description complexity ". specifically, we consider $ m \ times n $ random matrices $ \ mathbf { x } $ of arbitrary distribution ( continuous, discrete, discrete - continuous mixture, or even singular ). with $ \ mathcal { s } $ an $ \ varepsilon $ - support set of $ \ mathbf { x } $, i. e., $ \ mathrm { p } [ \ mathbf { x } \ in \ mathcal { s } ] \ geq 1 - \ varepsilon $, and $ \ underline { \ mathrm { dim } } _ \ mathrm { b } ( \ mathcal { s } ) $ denoting the lower minkowski dimension of $ \ mathcal { s } $, we show that $ k > \ underline { \ mathrm { dim } } _ \ mathrm { b } ( \ mathcal { s } ) $ trace inner product measurements with measurement matrices $ a _ i $, suffice to recover $ \ mathbf { x } $ with probability of error at most $ \ varepsilon $. the result holds for lebesgue a. a. $ a _ i $ and does not need incoherence between the $ a _ i $ and the unknown matrix $ \ mathbf { x } $. we furthermore show that $ k > \ underline { \ mathrm { dim } } _ \ mathrm { b } ( \ mathcal { s } ) $ measurements also suffice to recover the unknown matrix $ \ mathbf { x } $ from measurements taken with rank - one $ a _ i $, again this applies to a. a. rank - one $ a _ i $. rank - one measurement matrices are attractive as they require less storage space than general measurement matrices and can be applied faster. particularizing our results to the recovery of low - rank matrices, we find that $ k > ( m + n - r ) r $ measurements are sufficient to recover matrices of rank at most $ r $. finally, we construct a class of rank - $ r $ matrices that can be recovered with arbitrarily small probability of error from $ k < ( m + n - r ) r $ measurements.
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arxiv:1504.04970
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the increasing volumes of astronomical data require practical methods for data exploration, access and visualisation. the hierarchical progressive survey ( hips ) is a healpix based scheme that enables a multi - resolution approach to astronomy data from the individual pixels up to the whole sky. we highlight the decisions and approaches that have been taken to make this scheme a practical solution for managing large volumes of heterogeneous data. early implementors of this system have formed a network of hips nodes, with some 250 diverse data sets currently available, with multiple mirror implementations for important data sets. this hierarchical approach can be adapted to expose big data in different ways. we describe how the ease of implementation, and local customisation of the aladin lite embeddable hips visualiser have been keys for promoting collaboration on hips.
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arxiv:1611.01312
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we discuss the procedure of rieffel induction of representations in the framework of formal deformation quantization of poisson manifolds. we focus on the central role played by algebraic notions of complete positivity.
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arxiv:math/0504235
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do elections efficiently aggregate politicians ' policy - relevant private information? this paper argues that politicians ' office motivation is an obstacle. in a two - candidate hotelling - downs model in which each candidate has socially - valuable policy information, we establish that equilibrium welfare is at best what can be obtained by disregarding one politician ' s information. we also find that for canonical information structures, politicians have an incentive to ` ` anti - pander ' ', i. e., to overreact to their information. some degree of pandering - - underreacting to information - - would be socially beneficial.
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arxiv:2406.17084
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we establish duality between real forms of the quantum deformation of the 4 - dimensional orthogonal group studied by fioresi et al. and the classification work made by borowiec et al.. classically these real forms are the isometry groups of $ \ mathbb { r } ^ 4 $ equipped with euclidean, kleinian or lorentzian metric. a general deformation, named $ q $ - linked, of each of these spaces is then constructed, together with the coaction of the corresponding isometry group.
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arxiv:1803.04730
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it is shown how a natural representation of perpetuities as asymptotically homogeneous in space markov chains allows to prove various asymptotic tail results for stable perpetuities and limit theorems for unstable ones. some of these results are new while others essentially improve moment conditions known in the literature. both subexponential and cram \ ' er ' s cases are considered.
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arxiv:1603.08410
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a link between structural ordering and slow dynamics has recently attracted much attention from the context of the origin of glassy slow dynamics. candidates for such structural order are icosahedral, exotic amorphous, and crystal - like. each type of order is linked to a different scenario of glass transition. here we experimentally access local structural order in polydisperse hard spheres by particle - level confocal microscopy. we identify the key structures as icosahedral and fcc - like order, both statistically associated with slow particles. however, when approaching the glass transition, the icosahedral order does not grow in size whereas crystal - like order grows. it is the latter that governs the dynamics and is linked to dynamic heterogeneity. this questions the direct role of the local icosahedral ordering in glassy slow dynamics and suggests that the growing lengthscale of structural order is essential for the slowing down of dynamics and the nonlocal cooperativity in particle motion.
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arxiv:1301.7228
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a sheared cube is made out of a cube by giving a shear to the body in one direction keeping one of the faces fixed. we investigate here the thermodynamic phase behavior of a family of such regular hard sheared cubes, each of the members of the family having a distinct angle made by the faces with the perpendicular on the fixed face. hard particle monte carlo ( hpmc ) has been performed with these anisotropic building blocks resulting entropy - driven self assembly. thereby computational evidence of discrete plastic crystal phase has been found in crystal. the discrete plastic crystal phase is known to form through the spontaneous self - assembly of certain polyhedra. throughout the entire solid regime particle orientations exhibit strong specific correlations before melting into a liquid, without any evidence of freely rotating plastic crystal at lower density solid. it has been thoroughly observed that geometrical attributes of the shapes don ' t determine any of the properties that designate this orientational disorder phase reported here. we also find that particle ' s rotational symmetric axes and one of the rotational symmetric axes of the unit cell of the crystal have a strong relationship in their alignment in space. these results, achieved with shapes having crystallographic point group symmetry, are investigated as being consistent with the phenomenology of discrete plastic crystal phase established in earlier works with hard particles having non - crystallographic point group symmetry.
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arxiv:2412.09963
|
science mission directorate collecting important scientific data for earth science, heliophysics, and astrophysics programs. in june 2022, nasa conducted its first rocket launch from a commercial spaceport outside the us. it launched a black brant ix from the arnhem space centre in australia. = = = = launch services program ( 1990 – present ) = = = = the nasa launch services program ( lsp ) is responsible for procurement of launch services for nasa uncrewed missions and oversight of launch integration and launch preparation activity, providing added quality and mission assurance to meet program objectives. since 1990, nasa has purchased expendable launch vehicle launch services directly from commercial providers, whenever possible, for its scientific and applications missions. expendable launch vehicles can accommodate all types of orbit inclinations and altitudes and are ideal vehicles for launching earth - orbit and interplanetary missions. lsp operates from kennedy space center and falls under the nasa space operations mission directorate ( somd ). = = = aeronautics research = = = the aeronautics research mission directorate ( armd ) is one of five mission directorates within nasa, the other four being the exploration systems development mission directorate, the space operations mission directorate, the science mission directorate, and the space technology mission directorate. the armd is responsible for nasa ' s aeronautical research, which benefits the commercial, military, and general aviation sectors. armd performs its aeronautics research at four nasa facilities : ames research center and armstrong flight research center in california, glenn research center in ohio, and langley research center in virginia. = = = = nasa x - 57 maxwell aircraft ( 2016 – present ) = = = = the nasa x - 57 maxwell is an experimental aircraft being developed by nasa to demonstrate the technologies required to deliver a highly efficient all - electric aircraft. the primary goal of the program is to develop and deliver all - electric technology solutions that can also achieve airworthiness certification with regulators. the program involves development of the system in several phases, or modifications, to incrementally grow the capability and operability of the system. the initial configuration of the aircraft has now completed ground testing as it approaches its first flights. in mid - 2022, the x - 57 was scheduled to fly before the end of the year. the development team includes staff from the nasa armstrong, glenn, and langley centers along with number of industry partners from the united states and italy. = = = = next generation air transportation system ( 2007 – present ) = = = = nasa is collaborating with the federal aviation administration and industry stakeholders to modernize
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https://en.wikipedia.org/wiki/NASA
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we construct a number of explicit examples of hyperbolic monopoles, with various charges and often with some platonic symmetry. the fields are obtained from instanton data in four - dimensional euclidean space that are invariant under a circle action, and in most cases the monopole charge is equal to the instanton charge. a key ingredient is the identification of a new set of constraints on adhm instanton data that are sufficient to ensure the circle invariance. unlike for euclidean monopoles, the formulae for the squared higgs field magnitude in the examples we construct are rational functions of the coordinates. using these formulae, we compute and illustrate the energy density of the monopoles. we also prove, for particular monopoles, that the number of zeros of the higgs field is greater than the monopole charge, confirming numerical results established earlier for euclidean monopoles. we also present some one - parameter families of monopoles analogous to known scattering events for euclidean monopoles within the geodesic approximation.
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arxiv:1207.2636
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