text stringlengths 1 3.65k | source stringlengths 15 79 |
|---|---|
massive machine type communication ( mmtc ) to serve billions of iot devices is considered to open a potential new market for the next generation cellular network. legacy cellular networks cannot meet the requirements of emerging mmtc applications, since they were designed for human - driven services. in order to provide supports for mmtc services, current research and standardization work focus on the improvement and adaptation of legacy networks. however, these solutions face challenges to enhance the service availability and improve the battery life of mmtc devices simultaneously. in this article, we propose to exploit a network controlled sidelink communication scheme to enable cellular network with better support for mmtc services. moreover, a context - aware algorithm is applied to ensure the efficiency of the proposed scheme and multiple context information of devices are taken into account. correspondingly, signaling schemes are also designed and illustrated in this work to facilitate the proposed technology. the signaling schemes enable the network to collect required context information with light signaling effort and thus network can derive a smart configuration for both the sidelink and cellular link. in order to demonstrate the improvements brought by our scheme, a system - level simulator is implemented and numerical results show that our scheme can simultaneously enhance both the service availability and battery life of sensors. | arxiv:1705.03734 |
in recent years, many proposals have arisen from research on privacy in smart metering. in one of the considered approaches, referred to as anonymization, smart meters transmit fine - grained electricity consumption values in such a way that the energy supplier can not exactly determine procedence. this paper measures the real privacy provided by such approach by taking into account that at the end of a billing period the energy supplier collects the overall electricity consumption of each meter for billing purposes. an entropy - based measure is proposed for quantifying privacy and determine the extent to which knowledge on the overall consumption of meters allows to re - identify anonymous fine - grained consumption values. | arxiv:2002.04863 |
this volume contains the papers presented at the 18th international overture workshop, held online on 7th december 2020. this event was the latest in a series of workshops around the vienna development method ( vdm ), the open - source project overture, and related tools and formalisms. vdm is one of the longest established formal methods for systems development. a lively community of researchers and practitioners has grown up in academia and industry has grown around the modelling languages ( vdm - sl, vdm + +, vdm - rt, cml ) and tools ( vdmtools, overture, crescendo, symphony, the into - cps chain, and viennatalk ). together, these provide a platform for work on modelling and analysis technology that includes static and dynamic analysis, test generation, execution support, and model checking. this workshop provided updates on the emerging technology of vdm / overture, including collaboration infrastructure, collaborative modelling and co - simulation for cyber - physical systems. | arxiv:2101.07261 |
this paper advances the state of the art by extending the study of the analogy between the spacetime fabric and elasticity. as no prior work exists about a potential spacetime thermal expansion coeff lambda, we explore the analogy of gr with the elasticity theory by considering the cosmological constant lambda as an additional space curvature of the space frame due to a thermal gradient coming from the cosmic web and the cold vacuum and we propose ( ( alphaxdeltat ) / e ) ^ 2 = ( 1 / ro ) ^ 2 = lambda with ro being the curvature radius of the space fabric. it follows from this analogy and from the supposed space model consisting of thin sheets of planck thickness lp curved by this thermal gradient deltat a possible thermal expansion coefficient of the equivalent elastic medium modeling the space alphas = ( lpxlambda ^ ( 1 / 2 ) ) / deltat of the order of alphas ( qft ) = 1. 16x10 - 6 k - 1. as space - time and not only space must be considered in gr, this paper also proposes an innovative approach which consists in introducing into the interval ds ^ 2 of special relativity a temp effect t, ( entropy variations correlated with time laps, based on temperature variations affecting always physically the clocks ) based on different thermal expansion coefficients for space and time with for the flow of time t : cxt / cxnxtau = ( kbxt ) / nxhxdeltat = alphatxdeltat. with t = 10 ^ 6 k, n = 1, the associate time interval is 4. 8x10 ^ - 17s and alphat = 1. 0x10 ^ - 6k ^ - 1. the consequence of these hypothesis is that dark energy potentially becomes a thermal space - time curvature ( ( alphafxt ) / lp ) ^ 2 with f equal to s or t depending of the temperature, the thermal entropy variation of the universe, the planck thickness and time, that increases since the bigbang, depending on thermal expansion coefficients for space - time alphas and alphat as a function respectively of lambda, kb / hxt, in opposition to space - time curvature gravity due to mass / energy density as described in gr. | arxiv:2310.01005 |
monocular depth estimation ( mde ) models have undergone significant advancements over recent years. many mde models aim to predict affine - invariant relative depth from monocular images, while recent developments in large - scale training and vision foundation models enable reasonable estimation of metric ( absolute ) depth. however, effectively leveraging these predictions for geometric vision tasks, in particular relative pose estimation, remains relatively under explored. while depths provide rich constraints for cross - view image alignment, the intrinsic noise and ambiguity from the monocular depth priors present practical challenges to improving upon classic keypoint - based solutions. in this paper, we develop three solvers for relative pose estimation that explicitly account for independent affine ( scale and shift ) ambiguities, covering both calibrated and uncalibrated conditions. we further propose a hybrid estimation pipeline that combines our proposed solvers with classic point - based solvers and epipolar constraints. we find that the affine correction modeling is beneficial to not only the relative depth priors but also, surprisingly, the " metric " ones. results across multiple datasets demonstrate large improvements of our approach over classic keypoint - based baselines and pnp - based solutions, under both calibrated and uncalibrated setups. we also show that our method improves consistently with different feature matchers and mde models, and can further benefit from very recent advances on both modules. code is available at https : / / github. com / markyu98 / madpose. | arxiv:2501.05446 |
we propose realizations of the poisson structures for the lax representations of three integrable $ n $ - body peakon equations, camassa - - holm, degasperis - - procesi and novikov. the poisson structures derived from the integrability structures of the continuous equations yield quadratic forms for the $ r $ - matrix representation, with the toda molecule classical $ r $ - matrix playing a prominent role. we look for a linear form for the $ r $ - matrix representation. aside from the camassa - - holm case, where the structure is already known, the two other cases do not allow such a presentation, with the noticeable exception of the novikov model at $ n = 2 $. generalized hamiltonians obtained from the canonical sklyanin trace formula for quadratic structures are derived in the three cases. | arxiv:2203.13593 |
in this work we discuss possible definitions of the mean value of the energy for a resonant ( gamow ) state. the mathematical and physical aspects of the formalism are reviewed. the concept of rigged hilbert space is used as a supportive tool in dealing with gamow - resonances. | arxiv:math-ph/0006027 |
in a continuing survey of active galactic nuclei observed by the far ultraviolet spectroscopic explorer, we provide a deeper analysis of intrinsic absorption features found in 35 objects. our survey is for low - redshift and moderate - luminosity objects, mostly seyfert galaxies. we find a strong correlation between maximum radial velocity and luminosity. we also examine the relationships between equivalent width ( ew ), full width at half maximum, velocity : and continuum flux. the correlation between velocity and luminosity has been explored previously by laor & brandt, but at a significantly higher redshift and heavily weighted by broad absorption line quasars. we also have examined each object with multiple observations for variability in each of the aforementioned quantities, and have characterized the variation of ew with the continuum flux. in our survey, we find that variability of o vi lambda1032, lambda1038 is less common than of the uv doublets of civ and n v seen at longer wavelengths, because the o vi absorption is usually saturated. lyman beta absorption variability is more frequent. in a target - by - target examination we find that broad absorption line absorption and narrow absorption line absorbers are related in terms of maximum outflow velocity and luminosity, and both can be exhibited in similar luminosity objects. we also find one object that shows radial velocity change, seven objects that show equivalent width variability, and two objects that show either transverse velocity changes or a change in ionization. | arxiv:0807.0162 |
we discuss here future neutrino detectors with physics goals ranging from the ev to the eev scale. the focus is on future enabling technologies for such detectors, rather than existing detectors or those under construction. the report includes methodologies across the broad spectrum of neutrino physics : liquid noble and other cryogenic detectors, includin lar and lxe tpcs ; photon - based detectors including technologies enabling hybrid cherenkov / scintillation detectors ; low - threshold detectors which use a wide variety of technologies to probe physics like coherent neutrino - nucleus scattering or detection of cosmic background neutrinos ; and ultra - high energy detectors including optical and radio detectors, as well as tracking detectors for use at the forward physics facility of the lhc | arxiv:2211.09669 |
road surface friction significantly impacts traffic safety and mobility. a precise road surface friction prediction model can help to alleviate the influence of inclement road conditions on traffic safety, level of service, traffic mobility, fuel efficiency, and sustained economic productivity. most related previous studies are laboratory - based methods that are difficult for practical implementation. moreover, in other data - driven methods, the demonstrated time - series features of road surface conditions have not been considered. this study employed a long - short term memory ( lstm ) neural network to develop a data - driven road surface friction prediction model based on historical data. the proposed prediction model outperformed the other baseline models in terms of the lowest value of predictive performance measurements. the influence of the number of time - lags and the predicting time interval on predictive accuracy was analyzed. in addition, the influence of adding road surface water thickness, road surface temperature and air temperature on predictive accuracy also were investigated. the findings of this study can support road maintenance strategy development and decision making, thus mitigating the impact of inclement road conditions on traffic mobility and safety. future work includes a modified lstm - based prediction model development by accommodating flexible time intervals between time - lags. | arxiv:1911.02372 |
we report the quantum calibration of a magnetic force microscope ( mfm ) by measuring the two - dimensional magnetic stray field distribution of the mfm tip using a single nitrogen vacancy ( nv ) center in diamond. from the measured stray field distribution and the mechanical properties of the cantilever a calibration function is derived allowing to convert mfm images to quantum calibrated stray field maps. this novel approach overcomes limitations of prior mfm calibration schemes and allows quantum calibrated nanoscale stray field measurements in a field range inaccessible to scanning nv magnetometry. quantum calibrated measurements of a stray field reference sample allow its use as a transfer standard, opening the road towards fast and easily accessible quantum traceable calibrations of virtually any mfm. | arxiv:2103.13785 |
answering complex queries on knowledge graphs is important but particularly challenging because of the data incompleteness. query embedding methods address this issue by learning - based models and simulating logical reasoning with set operators. previous works focus on specific forms of embeddings, but scoring functions between embeddings are underexplored. in contrast to existing scoring functions motivated by local comparison or global transport, this work investigates the local and global trade - off with unbalanced optimal transport theory. specifically, we embed sets as bounded measures in $ \ real $ endowed with a scoring function motivated by the wasserstein - fisher - rao metric. such a design also facilitates closed - form set operators in the embedding space. moreover, we introduce a convolution - based algorithm for linear time computation and a block - diagonal kernel to enforce the trade - off. results show that wfre can outperform existing query embedding methods on standard datasets, evaluation sets with combinatorially complex queries, and hierarchical knowledge graphs. ablation study shows that finding a better local and global trade - off is essential for performance improvement. | arxiv:2305.04034 |
we present the first case of a highly collimated, extremely high velocity bipolar outflow in taurus. it is powered by the low - luminosity ( 0. 4 l _ sun ) source iras 04166 + 2706 and contains gas accelerated up to 50 km / s with respect to the ambient cloud both toward the blue and the red ( uncorrected for projection ). at the highest velocities, the outflow collimation factor exceeds 20, and the gas displays a very high degree of spatial symmetry. this very fast gas presents multiple maxima, and most likely arises from the acceleration of ambient material by a time - variable jet - like stellar wind. when scaled for luminosity, the outflow parameters of iras 04166 are comparable to those of other extremely high velocity outflows like l1448, indicating that even the very quiescent star - formation mode of taurus can produce objects powering very high energy flows ( l _ mec / l _ * > 0. 15 ). | arxiv:astro-ph/0406539 |
selection rules of ultrasound attenuation and sound velocity renormalization are analyzed in view of their potential application to identify pomeranchuk instabilities ( electronic nematic phase ). it is shown that the transverse sound attenuation along [ 110 ] direction is enhanced by the fermi surface fluctuations near a d _ { x2 - y2 } - wave pomeranchuk instability, while the attenuation along [ 100 ] direction remains unaffected. moreover the fluctuation regime above the instability is analyzed by means of a self - consistent renormalization scheme. the results could be applied directly to sr3ru2o7 which is a potential candidate for a pomeranchuk instability at its metamagnetic transition in strong magnetic fields. | arxiv:0907.2081 |
we study the integrability of a ( almost ) complex structure calibrated by a symplectic form. we find new sufficent conditions. | arxiv:math/0607236 |
we show that the eigenvectors of the pt - symmetric imaginary cubic oscillator are complete, but do not form a riesz basis. this results in the existence of a bounded metric operator having intrinsic singularity reflected in the inevitable unboundedness of the inverse. moreover, the existence of non - trivial pseudospectrum is observed. in other words, there is no quantum - mechanical hamiltonian associated with it via bounded and boundedly invertible similarity transformations. these results open new directions in physical interpretation of pt - symmetric models with intrinsically singular metric, since their properties are essentially different with respect to self - adjoint hamiltonians, for instance, due to spectral instabilities. | arxiv:1208.1866 |
accurate estimation of question difficulty and prediction of student performance play key roles in optimizing educational instruction and enhancing learning outcomes within digital learning platforms. the elo rating system is widely recognized for its proficiency in predicting student performance by estimating both question difficulty and student ability while providing computational efficiency and real - time adaptivity. this paper presents an adaptation of a multi concept variant of the elo rating system to the data collected by a medical training platform, a platform characterized by a vast knowledge corpus, substantial inter - concept overlap, a huge question bank with significant sparsity in user question interactions, and a highly diverse user population, presenting unique challenges. our study is driven by two primary objectives : firstly, to comprehensively evaluate the elo rating systems capabilities on this real - life data, and secondly, to tackle the issue of imprecise early stage estimations when implementing the elo rating system for online assessments. our findings suggest that the elo rating system exhibits comparable accuracy to the well - established logistic regression model in predicting final exam outcomes for users within our digital platform. furthermore, results underscore that initializing elo rating estimates with historical data remarkably reduces errors and enhances prediction accuracy, especially during the initial phases of student interactions. | arxiv:2403.07908 |
it is shown that the limits of the nested subclasses of five classes of infinitely divisible distributions on $ r ^ d $, which are the jurek class, the goldie - steutel - bondesson class, the class of selfdecomposable distributions, the thorin class and the class of generalized type $ g $ distributions, are identical with the closure of the class of stable distributions. more general results are also given. | arxiv:0712.0206 |
we consider the cosmology that results if our observable universe is a 3 - brane in a higher dimensional universe. in particular, we focus on the case where our 3 - brane is located at the $ z _ 2 $ symmetry fixed plane of a $ z _ 2 $ symmetric five - dimensional spacetime, as in the ho \ v { r } ava - witten model compactified on a calabi - yau manifold. as our first result, we find that there can be substantial modifications to the standard friedmann - robertson - walker ( frw ) cosmology ; as a consequence, a large class of such models is observationally inconsistent. in particular, any relationship between the hubble constant and the energy density on our brane is possible, including ( but not only ) frw. generically, due to the existence of the bulk and the boundary conditions on the orbifold fixed plane, the relationship is not frw, and hence cosmological constraints coming from big bang nucleosynthesis, structure formation, and the age of the universe difficult to satisfy. we do wish to point out, however, that some specific choices for the bulk stress - energy tensor components do reproduce normal frw cosmology on our brane, and we have constructed an explicit example. as our second result, for a broad class of models, we find a somewhat surprising fact : the stabilization of the radius of the extra dimension and hence the four dimensional planck mass requires unrealistic fine - tuning of the equation of state on our 3 - brane. in the last third of the paper, we make remarks about causality and the horizon problem that apply to { \ it any } theory in which the volume of the extra dimension determines the four - dimensional gravitational coupling. we point out that some of the assumptions that lead to the usual inflationary requirements are modified. | arxiv:hep-ph/9906542 |
beneficial from fully convolutional neural networks ( fcns ), saliency detection methods have achieved promising results. however, it is still challenging to learn effective features for detecting salient objects in complicated scenarios, in which i ) non - salient regions may have " salient - like " appearance ; ii ) the salient objects may have different - looking regions. to handle these complex scenarios, we propose a feature guide network which exploits the nature of low - level and high - level features to i ) make foreground and background regions more distinct and suppress the non - salient regions which have " salient - like " appearance ; ii ) assign foreground label to different - looking salient regions. furthermore, we utilize a multi - scale feature extraction module ( mfem ) for each level of abstraction to obtain multi - scale contextual information. finally, we design a loss function which outperforms the widely - used cross - entropy loss. by adopting four different pre - trained models as the backbone, we prove that our method is very general with respect to the choice of the backbone model. experiments on five challenging datasets demonstrate that our method achieves the state - of - the - art performance in terms of different evaluation metrics. additionally, our approach contains fewer parameters than the existing ones, does not need any post - processing, and runs fast at a real - time speed of 28 fps when processing a 480 x 480 image. | arxiv:1911.13168 |
in this paper we show that the diphoton mass spectrum in proton - proton collisions at the lhc is sensitive to the top quark flavor changing neutral current in the vertices of $ tu \ gamma $ and $ tc \ gamma $. the diphoton mass spectrum measured by the cms experiment at the lhc at a center - of - mass energy of 8 tev and an integrated luminosity of 19. 5 fb $ ^ { - 1 } $ is used as an example to set limits on these fcnc couplings. it is also shown that the angular distribution of the diphotons is sensitive to anomalous $ tu \ gamma $ and $ tc \ gamma $ couplings and it is a powerful tool to probe any value of the branching fraction of top quark rare decay to an up - type quark plus a photon down to the order of $ 10 ^ { - 4 } $. we also show that the $ tu \ gamma $ fcnc coupling has a significant contribution to the neutron electric dipole moment ( edm ) and the upper bound on neutron edm can be used to constrain the $ tu \ gamma $ fcnc coupling. | arxiv:1511.00220 |
we present a superior proof that the results for summed strength isovector dipole, spin dipole, and orbital dipole excitations are independent of deformations at the delta n = 0 level. | arxiv:nucl-th/0001021 |
we give a new proof of the hodge conjecture for abelian fourfolds of weil type with discriminant 1 and all of their powers. the hodge conjecture for these abelian fourfolds was proven by markman using hyperholomorphic sheaves on hyper - k \ " ahler varieties of generalized kummer type, and by constructing semiregular sheaves on abelian varieties. our proof instead relies on a direct geometric relation between abelian fourfolds of weil type with discriminant 1 and the six - dimensional hyper - k \ " ahler varieties $ \ widetilde { k } $ of o ' grady type arising as crepant resolutions $ \ widetilde { k } \ to k $ of a locally trivial deformation of a singular moduli space of sheaves on an abelian surface. as applications, we establish the hodge conjecture and the tate conjecture for any variety $ \ widetilde { k } $ of og6 - type as above, and all of its powers. | arxiv:2504.13607 |
in recent years, self - supervised contrastive learning has emerged as a distinguished paradigm in the artificial intelligence landscape. it facilitates unsupervised feature learning through contrastive delineations at the instance level. however, crafting an effective self - supervised paradigm remains a pivotal challenge within this field. this paper delves into two crucial factors impacting self - supervised contrastive learning - bach size and pretext tasks, and from a data processing standpoint, proposes an adaptive technique of batch fusion. the proposed method, via dimensionality reduction and reconstruction of batch data, enables formerly isolated individual data to partake in intra - batch communication through the embedding layer. moreover, it adaptively amplifies the self - supervised feature encoding capability as the training progresses. we conducted a linear classification test of this method based on the classic contrastive learning framework on imagenet - 1k. the empirical findings illustrate that our approach achieves state - of - the - art performance under equitable comparisons. benefiting from its " plug - and - play " characteristics, we further explored other contrastive learning methods. on the imagenet - 100, compared to the original performance, the top1 has seen a maximum increase of 1. 25 %. we suggest that the proposed method may contribute to the advancement of data - driven self - supervised learning research, bringing a fresh perspective to this community. | arxiv:2311.09974 |
the article is addressing a possibility of implementation of spin network states on adiabatic quantum computer. the discussion is focused on application of currently available technologies and analyzes a concrete example of d - wave machine. a class of simple spin network states which can be implemented on the chimera graph architecture of the d - wave quantum processor is introduced. however, extension beyond the currently available quantum processor topologies is required to simulate more sophisticated spin network states, which may inspire development of new generations of adiabatic quantum computers. a possibility of simulating loop quantum gravity is discussed and a method of solving a graph non - changing scalar ( hamiltonian ) constraint with the use of adiabatic quantum computations is proposed. | arxiv:1801.06017 |
binary droplet collisions are of importance in a variety of practical applications comprising dispersed two - phase flows. the background of our research is the prediction of properties of particulate products formed in spray processes. to gain a more thorough understanding of the elementary sub - processes inside a spray, experiments and direct numerical simulations of binary droplet collisions are used. the aim of these investigations is to develop semi - analytical descriptions for the outcome of droplet collisions. such collision models can then be employed as closure terms for scale - reduced simulations. in the present work we focus on the collision of droplets of different liquids. these kinds of collisions take place in every spray drying process when droplets with different solids contents collide in recirculation zones. a new experimental method has been developed allowing for high spatial and time resolved recordings via laser - induced fluorescence. the results obtained with the proposed method will be compared with dns simulations. the viscosities of the droplets are different whereas the interfacial tension and density are equal. the liquids are miscible and no surface tension is acting between the two liquids. our intention is to discover elementary phenomena caused by the viscosity ratio of the droplets. | arxiv:1210.6234 |
radio observations in the ammonia inversion lines of four comets, c / 2001 a2 ( linear ), 153p / ikeya - zhang, c / 2001 q4 ( neat ) and c / 2002 t7 ( linear ), were performed at the effelsberg 100 - m radio telescope during their respective close approaches to earth. none of the four lowest energy metastable lines ( j, k = j ), j = 1 - - 4, could be detected in these comets. we derive the following 3 sigma upper bounds on the nh _ 3 production rate, and c omparing to the corresponding water production rates, percentage nh _ 3 abundances relative to h _ 2o : q ( nh _ 3 ) < 1. 9x10 ^ 26 s ^ - 1 ( 0. 63 % ) for c / 2001 a2 ( linear ), q ( nh _ 3 ) < 2. 7x10 ^ 26 s ^ - 1 ( 0. 13 % ) for c / 2001 q4 ( neat ), q ( nh _ 3 ) < 2. 3x10 ^ 27 s ^ - 1 ( 0. 74 % ) for c / 2002 t7 ( linear ) and q ( nh _ 3 ) < = 6. 3x10 ^ 26 s ^ - 1 ( 0. 63 % ) for comet 153p / ikeya - zhang. at 0. 74 % or less, the ammonia - to - water ratios are factors of 2 below the value for c / 1995 o1 ( hale - bopp ) and 1p / halley, suggesting chemical diversity between comets. the 18 - cm lines of oh were clearly detected in the two comets observed during the 2004 campaign, thereby validating the cometary ephemerides. | arxiv:astro-ph/0505439 |
to properly reflect the main purpose of this work, we have changed the paper title to : a deterministic equivalent for the analysis of non - gaussian correlated mimo multiple access channels | arxiv:1104.5415 |
recent results by andrews and merca on the number of even parts in all partitions of n into distinct parts, a ( n ), were derived via generating functions. this paper extends these results to the number of parts divisible by k in all the partitions of n for which the multiplicity of each part is strictly less than k, ak ( n ). moreover, a combinatorial proof is provided using an extension of glaisher ' s bijection. finally, we give the generating functions for this new family of integer sequences and use it to verify generalized pentagonal, triangular, and square power recurrence relations. | arxiv:2010.02788 |
context : seasonal variations and climate stability of a planet are very sensitive to the planet obliquity and its evolution. this is of particular interest for the emergence and sustainability of land - based life, but orbital and rotational parameters of exoplanets are still poorly constrained. numerical explorations usually realised in this situation are thus in heavy contrast with the uncertain nature of the available data. aims : we aim to provide an analytical formulation of the long - term spin - axis dynamics of exoplanets, linking it directly to physical and dynamical parameters, but still giving precise quantitative results if the parameters are well known. together with bounds for the poorly constrained parameters of exoplanets, this analysis is designed to allow a quick and straightforward exploration of the spin - axis dynamics. methods : the long - term orbital solution is decomposed in quasi - periodic series and the spin - axis hamiltonian is expanded in powers of eccentricity and inclination. chaotic zones are measured by the resonance overlap criterion. bounds for the poorly known parameters of exoplanets are obtained from physical grounds ( rotational breakup ) and dynamical considerations ( equipartition of amd ). results : this method gives accurate results when the orbital evolution is well known. the chaotic zones for planets of the solar system can be retrieved in details from simple analytical formulas. for less constrained planetary systems, the maximal extent of the chaotic regions can be computed, requiring only the mass, the semi - major axis and the eccentricity of the planets present in the system. additionally, some estimated bounds of the precession constant allow to classify which observed exoplanets are necessarily out of major spin - orbit secular resonances ( unless the precession rate is affected by the presence of massive satellites ). | arxiv:1901.02831 |
we study the hamiltonian dynamics of the dust - bianchi ix universe in dust time gauge. this model has three physical metric degrees of freedom, with evolution determined by a time - independent physical hamiltonian. this approach gives a new physical picture where dust - bianchi ix dynamics is described by oscillations between dust - kasner solutions, rather than between vacuum - kasner solutions. we derive a generalized transition law between these phases, which has a matter component. sufficiently close to a singularity, we show that this law reduces to the vacuum belinski - khalatnikov - lifshitz map. we include an analysis with dust and a scalar field. lastly, we describe a path integral quantization using the dust - time physical hamiltonian and derive an effective action for the dust - kasner model by integrating out the anisotropy degrees of freedom. | arxiv:1707.07098 |
superspec is a pathfinder for future lithographic spectrometer cameras, which promise to energize extra - galactic astrophysics at ( sub ) millimeter wavelengths : delivering 200 - - 500 km / s spectral velocity resolution over an octave bandwidth for every pixel in a telescope ' s field of view. we present circuit simulations that prove the concept, which enables complete millimeter - band spectrometer devices in just a few square - millimeter footprint. we evaluate both single - stage and two - stage channelizing filter designs, which separate channels into an array of broad - band detectors, such as bolometers or kinetic inductance detector ( kid ) devices. we discuss to what degree losses ( by radiation or by absorption in the dielectric ) and fabrication tolerances affect the resolution or performance of such devices, and what steps we can take to mitigate the degradation. such design studies help us formulate critical requirements on the materials and fabrication process, and help understand what practical limits currently exist to the capabilities these devices can deliver today or over the next few years. | arxiv:1211.0934 |
nowadays, deep neural networks ( dnns ) are the core enablers for many emerging edge ai applications. conventional approaches to training dnns are generally implemented at central servers or cloud centers for centralized learning, which is typically time - consuming and resource - demanding due to the transmission of a large amount of data samples from the device to the remote cloud. to overcome these disadvantages, we consider accelerating the learning process of dnns on the mobile - edge - cloud computing ( mecc ) paradigm. in this paper, we propose hiertrain, a hierarchical edge ai learning framework, which efficiently deploys the dnn training task over the hierarchical mecc architecture. we develop a novel \ textit { hybrid parallelism } method, which is the key to hiertrain, to adaptively assign the dnn model layers and the data samples across the three levels of edge device, edge server and cloud center. we then formulate the problem of scheduling the dnn training tasks at both layer - granularity and sample - granularity. solving this optimization problem enables us to achieve the minimum training time. we further implement a hardware prototype consisting of an edge device, an edge server and a cloud server, and conduct extensive experiments on it. experimental results demonstrate that hiertrain can achieve up to 6. 9x speedup compared to the cloud - based hierarchical training approach. | arxiv:2003.09876 |
the fundamental capacity limits of intelligent reflecting surface ( irs ) - assisted multi - user wireless communication systems are investigated in this paper. specifically, the capacity and rate regions for both capacity - achieving non - orthogonal multiple access ( noma ) and orthogonal multiple access ( oma ) transmission schemes are characterized under the constraints of a maximum number of irs reconfiguration times. for noma, the ideal case with asymptotically large number of irs reconfiguration times is considered, where the optimal solution is obtained by employing the lagrange duality method. inspired by this result, an inner bound of the capacity region for the general case with a finite number of irs reconfiguration times is derived. for oma, the optimal transmission strategy for the ideal case is to serve each individual user alternatingly with its effective channel power gain maximized. based on this result, a rate region inner bound for the general case is derived. finally, numerical results are provided to show that : i ) a significant capacity and rate region improvement can be achieved by using irs ; ii ) the capacity gain can be further improved by dynamically configuring the irs reflection matrix. | arxiv:2001.03913 |
neural collapse refers to the remarkable structural properties characterizing the geometry of class embeddings and classifier weights, found by deep nets when trained beyond zero training error. however, this characterization only holds for balanced data. here we thus ask whether it can be made invariant to class imbalances. towards this end, we adopt the unconstrained - features model ( ufm ), a recent theoretical model for studying neural collapse, and introduce simplex - encoded - labels interpolation ( seli ) as an invariant characterization of the neural collapse phenomenon. specifically, we prove for the ufm with cross - entropy loss and vanishing regularization that, irrespective of class imbalances, the embeddings and classifiers always interpolate a simplex - encoded label matrix and that their individual geometries are determined by the svd factors of this same label matrix. we then present extensive experiments on synthetic and real datasets that confirm convergence to the seli geometry. however, we caution that convergence worsens with increasing imbalances. we theoretically support this finding by showing that unlike the balanced case, when minorities are present, ridge - regularization plays a critical role in tweaking the geometry. this defines new questions and motivates further investigations into the impact of class imbalances on the rates at which first - order methods converge to their asymptotically preferred solutions. | arxiv:2208.05512 |
answering simple questions over knowledge graphs is a well - studied problem in question answering. previous approaches for this task built on recurrent and convolutional neural network based architectures that use pretrained word embeddings. it was recently shown that finetuning pretrained transformer networks ( e. g. bert ) can outperform previous approaches on various natural language processing tasks. in this work, we investigate how well bert performs on simplequestions and provide an evaluation of both bert and bilstm - based models in datasparse scenarios. | arxiv:2001.11985 |
plasma window is an advanced apparatus which can work as the interface between vacuum and high pressure region. it can be used in many applications which need atmosphere - vacuum interface, such as gas target, electron beam welding, synchrotron radiation and spallation neutron source. a test bench of plasma window is constructed in peking university. a series of experiments and corresponding parameter measurements have been presented in this article. the experiment result indicates the feasibility of such a facility acting as an interface between vacuum and high pressure region. | arxiv:1308.5524 |
we show that a partially hyperbolic system can have at most a finite number of compact center - stable submanifolds. we also give sufficient conditions for these submanifolds to exist and consider the question of whether they can intersect each other. | arxiv:1612.03535 |
in real industrial processes, fault diagnosis methods are required to learn from limited fault samples since the procedures are mainly under normal conditions and the faults rarely occur. although attention mechanisms have become popular in the field of fault diagnosis, the existing attention - based methods are still unsatisfying for the above practical applications. first, pure attention - based architectures like transformers need a large number of fault samples to offset the lack of inductive biases thus performing poorly under limited fault samples. moreover, the poor fault classification dilemma further leads to the failure of the existing attention - based methods to identify the root causes. to address the aforementioned issues, we innovatively propose a supervised contrastive convolutional attention mechanism ( sccam ) with ante - hoc interpretability, which solves the root cause analysis problem under limited fault samples for the first time. the proposed sccam method is tested on a continuous stirred tank heater and the tennessee eastman industrial process benchmark. three common fault diagnosis scenarios are covered, including a balanced scenario for additional verification and two scenarios with limited fault samples ( i. e., imbalanced scenario and long - tail scenario ). the comprehensive results demonstrate that the proposed sccam method can achieve better performance compared with the state - of - the - art methods on fault classification and root cause analysis. | arxiv:2302.01599 |
a radiatively stable de sitter spacetime is constructed by considering an intrinsically non - commutative and generalized - geometric formulation of string theory, which is related to a family of f - theory models endowed with non - trivial anisotropic axion - dilaton backgrounds. in particular, the curvature of the canonically conjugate dual space provides for a positive cosmological constant to leading order, that satisfies a radiatively stable see - saw - like formula, which in turn induces the dark energy in the observed spacetime. we also comment on the non - commutative phase of the non - perturbative formulations of string theory / quantum gravity implied by this approach. | arxiv:1905.08269 |
we present the first magic / fermi - lat joint search for dark matter annihilation gamma - ray signals from dwarf satellite galaxies. we combine 158 hours of observations of segue 1 by magic with 6 - years observations of 15 dwarf satellite galaxies by the fermi - lat. we obtain limits on the annihilation cross - section for dark matter particle masses between 10 gev and 100 tev - the widest mass range ever explored by a coherent and comprehensive analysis. our new inclusive analysis approach is completely generic, and we propose to use it to perform a global, sensitivity - optimized dark matter search by combining data from present and future gamma - ray and neutrino detectors. | arxiv:1508.05827 |
dab +, notably norway in 2017 and switzerland in 2024. a single dab station transmits a 1, 500 khz bandwidth signal that carries from 9 – 12 channels of digital audio modulated by ofdm from which the listener can choose. broadcasters can transmit a channel at a range of different bit rates, so different channels can have different audio quality. in different countries dab stations broadcast in either band iii ( 174 – 240 mhz ) or l band ( 1. 452 – 1. 492 ghz ) in the uhf range, so like fm reception is limited by the visual horizon to about 40 miles ( 64 km ). hd radio is an alternative digital radio standard widely implemented in north america. an in - band on - channel technology, hd radio broadcasts a digital signal in a subcarrier of a station ' s analog fm or am signal. stations are able to multicast more than one audio signal in the subcarrier, supporting the transmission of multiple audio services at varying bitrates. the digital signal is transmitted using ofdm with the hdc ( high - definition coding ) proprietary audio compression format. hdc is based on, but not compatible with, the mpeg - 4 standard he - aac. it uses a modified discrete cosine transform ( mdct ) audio data compression algorithm. digital radio mondiale ( drm ) is a competing digital terrestrial radio standard developed mainly by broadcasters as a higher spectral efficiency replacement for legacy am and fm broadcasting. mondiale means " worldwide " in french and italian ; drm was developed in 2001, and is currently supported by 23 countries, and adopted by some european and eastern broadcasters beginning in 2003. the drm30 mode uses the commercial broadcast bands below 30 mhz, and is intended as a replacement for standard am broadcast on the longwave, mediumwave, and shortwave bands. the drm + mode uses vhf frequencies centered around the fm broadcast band, and is intended as a replacement for fm broadcasting. it is incompatible with existing radio receivers, so it requires listeners to purchase a new drm receiver. the modulation used is a form of ofdm called cofdm in which, up to 4 carriers are transmitted on a channel formerly occupied by a single am or fm signal, modulated by quadrature amplitude modulation ( qam ). the drm system is designed to be as compatible as possible with existing am and fm radio transmitters, so that much of the equipment in existing radio stations can continue in use, augmented with drm modulation equipment. satellite radio is | https://en.wikipedia.org/wiki/Radio |
this paper gives the commensurability classification of deligne - mostow ball quotients and shows that the 104 deligne - mostow lattices form 38 commensurability classes. firstly, we find commensurability relations among deligne - mostow monodromy groups, which are not necessarily discrete. this recovers and generalizes previous work by sauter and deligne - mostow in dimension two. in this part, we consider certain projective surfaces with two fibrations over the projective line, which induce two sets of deligne - mostow data. the correspondences of moduli spaces provide the geometric realization of commensurability relations. secondly, we obtain commensurability invariants from conformal classes of hermitian forms and toroidal boundary divisors. this completes the commensurability classification of deligne - mostow lattices and also reproves kappes - moller and mcmullen ' s results on non - arithmetic deligne - mostow lattices. | arxiv:2411.09682 |
the most efficient energy sources known in the universe are accretion disks. those around black holes convert 5 - - 40 per cent of rest - mass energy to radiation. like water circling a drain, inflowing mass must lose angular momentum, presumably by vigorous turbulence in disks, which are essentially inviscid. the origin of the turbulence is unclear. hot disks of electrically conducting plasma can become turbulent by way of the linear magnetorotational instability. cool disks, such as the planet - forming disks of protostars, may be too poorly ionized for the magnetorotational instability to occur, hence essentially unmagnetized and linearly stable. nonlinear hydrodynamic instability often occurs in linearly stable flows ( for example, pipe flows ) at sufficiently large reynolds numbers. although planet - forming disks have extreme reynolds numbers, keplerian rotation enhances their linear hydrodynamic stability, so the question of whether they can be turbulent and thereby transport angular momentum effectively is controversial. here we report a laboratory experiment, demonstrating that non - magnetic quasi - keplerian flows at reynolds numbers up to millions are essentially steady. scaled to accretion disks, rates of angular momentum transport lie far below astrophysical requirements. by ruling out purely hydrodynamic turbulence, our results indirectly support the magnetorotational instability as the likely cause of turbulence, even in cool disks. | arxiv:astro-ph/0611481 |
the aim of this paper is to perform stability analysis of anisotropic dissipative cylindrical collapsing model in $ f ( r, t, r _ { \ mu \ nu } t ^ { \ mu \ nu } ) $ gravity. in this context, the modified version of hydrodynamical equation is explored by means of dynamical equations and radial perturbation scheme. we examined the role of adiabatic index, dissipation as well as the particular cosmological model on the onset of dynamical instability of the evolving cylindrical system that was initially in hydrostatic equilibrium with newtonian and post newtonian approximations. it is pointed out that extra curvature terms of $ f ( r, t, r _ { \ mu \ nu } t ^ { \ mu \ mu \ nu } ) $ gravity tends to increase the stability, while that heat radiations push the system to enter into unstable window. further, our results reveal the significance of adiabatic index in the stability analysis of cylindrical celestial model. | arxiv:1709.04365 |
given a group g, the conjugacy problem in g is the problem of giving an effective procedure for determining whether or not two given elements f, g of g are conjugate, i. e. whether there exists h belonging to g with fh = hg. this paper is about the conjugacy problem in the group diffeo ( i ) of all diffeomorphisms of an interval i in r. there is much classical work on the subject, solving the conjugacy problem for special classes of maps. unfortunately, it is also true that many results and arguments known to the experts are difficult to find in the literature, or simply absent. we try to repair these lacunae, by giving a systematic review, and we also include new results about the conjugacy classification in the general case. | arxiv:0911.0804 |
motivated by the astrophysical problems of star formations from molecular clouds, we make the first step on the possible long time behaviors of certain irregularly - shaped molecular clouds. we emphasis the main difficulty of the blowups of the irregular - shaped fluids with vacuum ( molecular clouds ) comes from the initial irregular configurations of its density ( multiple centers of gravity ). this inevitably causes far more complicated movements during the evolution than the one with spherical symmetry. the spherical symmetric case has been well studied. however, for the non - spherical symmetric case with the gravity, it is very rare in the references due to a very complicate nonlinear interaction between the gravity and the fluids. this article concludes, under the admissible data ( i. e., large scale, irregularly - shaped, expanding and rotational molecular clouds ), the developments of the solution ( molecular clouds ) are either global ( the first class ) with near - boundary mass accretions ( leads to star formations ), or blowup at finite time. in addition, certain singularities can be removed from the boundary if the data is strongly admissible. this paper partially answers makino ' s conjecture [ 37 ] in 1992 on the finite time blowup of any tame solution without symmetries for some data and the model of the molecular clouds and the local wellposedness have been established in the companion article [ 30 ]. | arxiv:2102.11550 |
we calculate the x - ray absorption near edge structure ( xanes ) modulating the ba 4d - photoabsorption cross section - the giant dipole resonance - centered around 110 ev photon energy for several models of spherical and non - spherical ba @ c _ n metallofullerene cage systems. in the cases considered, the xanes interference patterns provide clear structural " fingerprints ", distinguishing between center versus off - center ba position and spherical versus deformed c _ n shell. | arxiv:cond-mat/9506041 |
majorana zero modes ( mzms ) emerge as edge states in topological superconductors and are promising for topological quantum computation, but their detection has so far been elusive. here we show that non - hermiticity can be used to obtain dramatically more robust mzms. the enhanced properties appear as a result of an extreme instability of exceptional points to superconductivity, such that even a vanishingly small superconducting order parameter already opens a large energy gap, produces well - localized mzms, and leads to strong superconducting pair correlations. our work thus illustrates the large potential of enhancing topological superconductivity using non - hermitian exceptional points. | arxiv:2206.15324 |
rgb j2243 + 203 is a blazar at an estimated redshift of greater than 0. 39 that has been classified both as an intermediate - frequency - peaked bl lac object and as a high - frequency - peaked bl lac object. this source has been detected by veritas at a statistical significance of 5. 6 $ \ sigma $ in $ \ sim $ 4 hours between 21 dec 2014 utc ( 57012 mjd ) and 24 dec 2014 utc ( 57015 mjd ). an integral flux of $ 2. 03 \ pm 0. 54 \ times 10 ^ { - 11 } \ textrm { cm } ^ { - 2 } \ textrm { s } ^ { - 1 } $ has been observed above 160 gev. the gamma - ray spectrum can be described as a simple power - law spectrum with spectral index of $ - 4. 64 \ pm 0. 56 $. veritas measurements are complemented by quasi - simultaneous fermi - lat and swift - xrt observations, in the energy ranges of 1 - 100 gev and 2 - 10 kev, respectively. during the three day time period of veritas observations, an increased flux level at 1 - 100 gev energies was detected compared to the flux from the first four years of fermi - lat observations. the swift - xrt observations were taken 2. 8 days after this period, and the integral x - ray flux in the energy range 0. 3 - 10 kev is not significantly higher than a baseline flux from archival data. | arxiv:1508.06334 |
adsorption energy scaling relationships have now developed beyond their original form, which was more targeted towards the optimization of catalytic sites and the reduction of computational costs in simulations. the recent surge of interest in the adsorption energy scaling relations is to explore the surfaces beyond the transition metals ( tms ) as well as reactions involving complicated molecules. breakdown of such scaling relationships leads to motivating the discovery of novel catalysts with enhanced capabilities. in this work, we report our extensive study on the linear scaling relation ( lsr ) between oxygen ( o ), a group via element with elements of neighbouring groups such as : group iiia ( boron ( b ), aluminum ( al ) ), iva ( carbon ( c ), silicon ( si ) ), va ( nitrogen ( n ), phosphorus ( p ) ) and viia ( florine ( f ) ) on magnetic bimetallic surfaces. we found that the slope is positive for only o versus n and f, remaining of the slopes are negative. the present model is based on multiple surface descriptors, particularly spin - averaged d - band center and the surface ' s magnetic moment, whereas the original scaling theory ( phys. rev. lett. 99, 016105 ( 2007 ) ) was based on a single adsorbate descriptor : adsorbate valency. | arxiv:2107.12092 |
we consider the issue of validating the relationship between electric fields and optical intensity as proposed by the classical theory of electromagnetism. we describe an interference scenario in which this can be checked using only intensity measurements and without any other information regarding the details of the arrangement of the associated fields. we implement this experimentally using a triple michelson interferometer and the results strongly suggest that the method validates the classical relationship between optical intensity and the associated classical field. | arxiv:2008.12641 |
in this paper we propose tools for high - order mesh optimization and demonstrate their benefits in the context of multi - material arbitrary lagrangian - eulerian ( ale ) compressible shock hydrodynamic applications. the mesh optimization process is driven by information provided by the simulation which uses the optimized mesh, such as shock positions, material regions, known error estimates, etc. these simulation features are usually represented discretely, for instance, as finite element functions on the lagrangian mesh. the discrete nature of the input is critical for the practical applicability of the algorithms we propose and distinguishes this work from approaches that strictly require analytical information. our methods are based on node movement through a high - order extension of the target - matrix optimization paradigm ( tmop ) of knupp. the proposed formulation is fully algebraic and relies only on local jacobian matrices, so it is applicable to all types of mesh elements, in 2d and 3d, and any order of the mesh. we discuss the notions of constructing adaptive target matrices and obtaining their derivatives, reconstructing discrete data in intermediate meshes, node limiting that enables improvement of global mesh quality while preserving space - dependent local mesh features, and appropriate normalization of the objective function. the adaptivity methods are combined with automatic ale triggers that can provide robustness of the mesh evolution and avoid excessive remap procedures. the benefits of the new high - order tmop technology are illustrated on several simulations performed in the high - order ale application blast. | arxiv:2001.11536 |
mu orionis was identified by spectroscopic studies as a quadruple star system. seventeen high precision differential astrometry measurements of mu ori have been collected by the palomar high - precision astrometric search for exoplanet systems ( phases ). these show both the motion of the long period binary orbit and short period perturbations superimposed on that caused by each of the components in the long period system being themselves binaries. the new measurements enable the orientations of the long period binary and short period subsystems to be determined. recent theoretical work predicts the distribution of relative inclinations between inner and outer orbits of hierarchical systems to peak near 40 and 140 degrees. the degree of coplanarity of this complex system is determined, and the angle between the planes of the a - b and aa - ab orbits is found to be 136. 7 + / - 8. 3 degrees, near the predicted distribution peak at 140 degrees ; this result is discussed in the context of the handful of systems with established mutual inclinations. the system distance and masses for each component are obtained from a combined fit of the phases astrometry and archival radial velocity observations. the component masses have relative precisions of 5 % ( component aa ), 15 % ( ab ), and 1. 4 % ( each of ba and bb ). the median size of the minor axes of the uncertainty ellipses for the new measurements is 20 micro - arcseconds. updated orbits for delta equulei, kappa pegasi, and v819 herculis are also presented. | arxiv:0710.2126 |
a new 2 - parameter quadratic deformation of the quantum oscillator algebra and its 1 - parameter deformed heisenberg subalgebra are considered. an infinite dimensional fock module representation is presented which at roots of unity contains null vectors and so is reducible to a finite dimensional representation. the cyclic, nilpotent and unitary representations are discussed. witten ' s deformation of $ sl _ 2 $ and some deformed infinite dimensional algebras are constructed from the $ 1d $ heisenberg algebra generators. the deformation of the centreless virasoro algebra at roots of unity is mentioned. finally the $ sl _ q ( 2 ) $ symmetry of the deformed heisenberg algebra is explicitly constructed. | arxiv:hep-th/9211009 |
value - at - risk ( var ) is one of the main regulatory tools used for risk management purposes. however, it is difficult to compute optimal var portfolios ; that is, an optimal risk - reward portfolio allocation using var as the risk measure. this is due to var being non - convex and of combinatorial nature. in particular, it is well known that the var portfolio problem can be formulated as a mixed integer linear program ( milp ) that is difficult to solve with current milp solvers for medium to large - scale instances of the problem. here, we present an algorithm to compute near - optimal var portfolios that takes advantage of this milp formulation and provides a guarantee of the solution ' s near - optimality. as a byproduct, we obtain an algorithm to compute tight lower bounds on the var portfolio problem that outperform related algorithms proposed in the literature for this purpose. the near - optimality guarantee provided by the proposed algorithm is obtained thanks to the relation between minimum risk portfolios satisfying a reward benchmark and the corresponding maximum reward portfolios satisfying a risk benchmark. these alternate formulations of the portfolio allocation problem have been frequently studied in the case of convex risk measures and concave reward functions. here, this relationship is considered for general risk measures and reward functions. to illustrate the efficiency of the presented algorithm, numerical results are presented using historical asset returns from the us financial market. | arxiv:2107.07339 |
we present radiation hydrodynamic simulations in which binary planets form by close encounters in a system of several super - earth embryos. the embryos are embedded in a protoplanetary disk consisting of gas and pebbles and evolve in a region where the disk structure supports convergent migration due to type i torques. as the embryos accrete pebbles, they become heated and thus affected by the thermal torque ( ben \ ' { i } tez - llambay et al. 2015 ) and the hot - trail effect ( chrenko et al. 2017 ) which excites orbital eccentricities. motivated by findings of eklund & masset ( 2017 ), we assume the hot - trail effect operates also vertically and reduces the efficiency of inclination damping. non - zero inclinations allow the embryos to become closely packed and also vertically stirred within the convergence zone. subsequently, close encounters of two embryos assisted by the disk gravity can form transient binary planets which quickly dissolve. binary planets with a longer lifetime $ \ sim $ $ 10 ^ { 4 } $ yr form in 3 - body interactions of a transient pair with one of the remaining embryos. the separation of binary components generally decreases in subsequent encounters and due to pebble accretion until the binary merges, forming a giant planet core. we provide an order - of - magnitude estimate of the expected occurrence rate of binary planets, yielding one binary planet per $ \ simeq $ $ 2 $ - - $ 5 \ times10 ^ { 4 } $ planetary systems. therefore, although rare, the binary planets may exist in exoplanetary systems and they should be systematically searched for. | arxiv:1810.12955 |
the learning - with - errors ( lwe ) problem is a crucial computational challenge with significant implications for post - quantum cryptography and computational learning theory. here we propose a quantum - classical hybrid algorithm with ising model ( hawi ) to address the lwe problem. our approach involves transforming the lwe problem into the shortest vector problem ( svp ), using variable qubits to encode lattice vectors into an ising hamiltonian. we then identify the low - energy levels of the hamiltonian to extract the solution, making it suitable for implementation on current noisy intermediate - scale quantum ( nisq ) devices. we prove that the number of qubits required is less than $ m ( 3m - 1 ) / 2 $, where $ m $ is the number of samples in the algorithm. our algorithm is heuristic, and its time complexity depends on the specific quantum algorithm employed to find the hamiltonian ' s low - energy levels. if the quantum approximate optimization algorithm ( qaoa ) is used to solve the ising hamiltonian problem, and the number of iterations satisfies $ y < o \ left ( m \ log m \ cdot 2 ^ { 0. 2972k } / pk ^ 2 \ right ) $, our algorithm will outperform the classical block korkine - zolotarev ( bkz ) algorithm, where $ k $ is the block size related to problem parameters, and $ p $ is the number of layers in qaoa. we demonstrate the algorithm by solving a $ 2 $ - dimensional lwe problem on a real quantum device with $ 5 $ qubits, showing its potential for solving meaningful instances of the lwe problem in the nisq era. | arxiv:2408.07936 |
we report a novel method to generate arbitrary optical focus arrays ( ofas ). our approach rapidly produces computer - generated holograms ( cghs ) to precisely control the positions and the intensities of the foci. this is achieved by replacing the fast fourier transform ( fft ) operation in the conventional iterative fourier - transform algorithm ( ifta ) with a linear algebra one, identifying / removing zero elements from the matrices, and employing a generalized weighting strategy. on the premise of accelerating the calculation speed by > 70 times, we demonstrate ofa with 99 % intensity precision in the experiment. our method proves effective and is applicable for the systems in which real - time ofa generation is essential. | arxiv:2206.12661 |
we investigate the influence of electron - phonon interactions on the dynamical properties of a quantum - dot - cavity qed system. we show that non - markovian effects in the phonon reservoir lead to strong changes in the dynamics, arising from photon - assisted dephasing processes, not present in markovian treatments. a pronounced consequence is the emergence of a phonon induced spectral asymmetry when detuning the cavity from the quantum - dot resonance. the asymmetry can only be explained when considering the polaritonic quasi - particle nature of the quantum - dot - cavity system. furthermore, a temperature induced reduction of the light - matter coupling strength is found to be relevant in interpreting experimental data, especially in the strong coupling regime. | arxiv:0909.3964 |
aging is driven by subcellular processes that are relatively well - understood. however the qualitative mechanisms and quantitative dynamics of how these micro - level failures cascade to a macro - level catastrophe in a tissue or organs remain largely unexplored. here we experimentally and theoretically study how cell failure propagates in a synthetic tissue in the presence of advective flow. we argue that cells secrete cooperative factors, thereby forming a network of interdependence governed by diffusion and flow, which fails with a propagating front parallel to advective circulation. | arxiv:2005.10746 |
time - varying parameter ( tvp ) regression models can involve a huge number of coefficients. careful prior elicitation is required to yield sensible posterior and predictive inferences. in addition, the computational demands of markov chain monte carlo ( mcmc ) methods mean their use is limited to the case where the number of predictors is not too large. in light of these two concerns, this paper proposes a new dynamic shrinkage prior which reflects the empirical regularity that tvps are typically sparse ( i. e. time variation may occur only episodically and only for some of the coefficients ). a scalable mcmc algorithm is developed which is capable of handling very high dimensional tvp regressions or tvp vector autoregressions. in an exercise using artificial data we demonstrate the accuracy and computational efficiency of our methods. in an application involving the term structure of interest rates in the eurozone, we find our dynamic shrinkage prior to effectively pick out small amounts of parameter change and our methods to forecast well. | arxiv:2005.03906 |
continuous - variable quantum key distribution exploits coherent measurements of the electromagnetic field, i. e., homodyne or heterodyne detection. the most advanced security proofs developed so far relied on idealised mathematical models for such measurements, which assume that the measurement outcomes are continuous and unbounded variables. as physical measurement devices have finite range and precision, these mathematical models only serve as an approximation. it is expected that, under suitable conditions, the predictions obtained using these simplified models are in good agreement with the actual experimental implementations. however, a quantitative analysis of the error introduced by this approximation, and of its impact on composable security, have been lacking so far. here we present a theory to rigorously account for the experimental limitations of realistic heterodyne detection. we focus on collective attacks, and present security proofs for the asymptotic and finite - size regimes, the latter within the framework of composable security. in doing this, we establish for the first time the composable security of discrete - modulation continuous - variable quantum key distribution in the finite - size regime. tight bounds on the key rates are obtained through semi - definite programming and do not rely on a truncation of the hilbert space. | arxiv:2108.00428 |
in the present paper we propose a mechanism of the structural instability with a periodic charge ordering in two - dimensional isotropic conductors with a closed fermi surface which completely excludes the conventional nesting mechanism. we show that the structural instability in such conductors may arise as a topological reconstruction under which the initially closed fermi surface is transformed into an open one. we have found that the order parameter of the charge ordering ground state may exceed one hundredth of the fermi energy. furthermore, this charge ordering is a quantum phase transition with respect to the dimensionless coupling constant $ \ lambda $ related to the mechanism that drives the band reconstruction ( e. g. electron - phonon coupling ), with the critical value given by $ \ lambda _ c = ( 1 + 2 / \ pi ) ^ { - 1 } $. preliminary estimations show that the suggested mechanism can be the origin of density waves observed in such materials as high $ - t _ c $ cuprates or graphite intercalates. | arxiv:1806.10943 |
we report the results of our hst snapshot survey with the acs hrc pr200l prism, designed to measure the near - uv emission in a sample of nearby m dwarfs. 33 stars were observed, spanning the mass range from 0. 1 - 0. 6 solar masses ( t _ eff ~ 2200k - 4000k ) where the uv energy distributions vary widely between active and inactive stars. these observations provide much - needed constraints on models of the habitability zone and the atmospheres of possible terrestrial planets orbiting m dwarf hosts, and will be useful in refining the target selection for future space missions such as tpf. we compare our data with a new generation of m dwarf atmospheric models and discuss their implication for the chromospheric energy budget. these nuv data will also be valuable in conjunction with existing optical, fuv and x - ray data to explore unanswered questions regarding the dynamo generation and magnetic heating in low - mass stars. | arxiv:0711.1861 |
##ieck universes is formally eliminable. one goal of the reverse mathematics program is to identify whether there are areas of " core mathematics " in which foundational issues may again provoke a crisis. = = see also = = aristotelian realist philosophy of mathematics mathematical logic brouwer – hilbert controversy church – turing thesis controversy over cantor ' s theory epistemology euclid ' s elements hilbert ' s problems implementation of mathematics in set theory liar paradox new foundations philosophy of mathematics principia mathematica quasi - empiricism in mathematics mathematical thought of charles peirce = = notes = = = = references = = avigad, jeremy ( 2003 ) number theory and elementary arithmetic, philosophia mathematica vol. 11, pp. 257 – 284 eves, howard ( 1990 ), foundations and fundamental concepts of mathematics third edition, dover publications, inc, mineola ny, isbn 0 - 486 - 69609 - x ( pbk. ) cf § 9. 5 philosophies of mathematics pp. 266 – 271. eves lists the three with short descriptions prefaced by a brief introduction. goodman, n. d. ( 1979 ), " mathematics as an objective science ", in tymoczko ( ed., 1986 ). hart, w. d. ( ed., 1996 ), the philosophy of mathematics, oxford university press, oxford, uk. hersh, r. ( 1979 ), " some proposals for reviving the philosophy of mathematics ", in ( tymoczko 1986 ). hilbert, d. ( 1922 ), " neubegrundung der mathematik. erste mitteilung ", hamburger mathematische seminarabhandlungen 1, 157 – 177. translated, " the new grounding of mathematics. first report ", in ( mancosu 1998 ). katz, robert ( 1964 ), axiomatic analysis, d. c. heath and company. kleene, stephen c. ( 1991 ) [ 1952 ]. introduction to meta - mathematics ( tenth impression 1991 ed. ). amsterdam ny : north - holland pub. co. isbn 0 - 7204 - 2103 - 9. in chapter iii a critique of mathematic reasoning, § 11. the paradoxes, kleene discusses intuitionism and formalism in depth. throughout the rest of the book he treats, and compares, both formalist ( classical ) and intuitionist logics with an emphasis | https://en.wikipedia.org/wiki/Foundations_of_mathematics |
the successive projection algorithm ( spa ) is a fast algorithm to tackle separable nonnegative matrix factorization ( nmf ). given a nonnegative data matrix $ x $, spa identifies an index set $ \ mathcal { k } $ such that there exists a nonnegative matrix $ h $ with $ x \ approx x ( :, \ mathcal { k } ) h $. spa has been successfully used as a pure - pixel search algorithm in hyperspectral unmixing and for anchor word selection in document classification. moreover, spa is provably robust in low - noise settings. the main drawbacks of spa are that it is not robust to outliers and does not take the data fitting term into account when selecting the indices in $ \ mathcal { k } $. in this paper, we propose a new spa variant, dubbed robust spa ( rspa ), that is robust to outliers while still being provably robust in low - noise settings, and that takes into account the reconstruction error for selecting the indices in $ \ mathcal { k } $. we illustrate the effectiveness of rspa on synthetic data sets and hyperspectral images. | arxiv:1908.04109 |
two constructions of lattice packings of $ n $ - dimensional cross - polytopes ( $ \ ell _ 1 $ balls ) are described, the density of which exceeds that of any prior construction by a factor of at least $ 2 ^ { \ frac { n } { \ ln n } ( 1 + o ( 1 ) ) } $ when $ n \ to \ infty $. the first family of lattices is explicit and is obtained by applying construction a to a class of reed - solomon codes. the second family has subexponential construction complexity and is based on the notion of sidon sets in finite abelian groups. the construction based on sidon sets also gives the highest known asymptotic density of packing discrete cross - polytopes of fixed radius $ r \ geqslant 3 $ in $ \ mathbb { z } ^ n $. | arxiv:2111.03343 |
if textbook lorentz invariance is actually a property of the equations describing a sector of the excitations of vacuum above some critical distance scale, several sectors of matter with different critical speeds in vacuum can coexist and an absolute rest frame ( the vacuum rest frame ) may exist without contradicting the apparent lorentz invariance felt by " ordinary " particles ( particles with critical speed in vacuum equal to $ c $, the speed of light ). sectorial lorentz invariance, reflected by the fact that all particles of a given dynamical sector have the same critical speed in vacuum, will then be an expression of a fundamental sectorial symmetry ( e. g. preonic grand unification or extended supersymmetry ) protecting a parameter of the equations of motion. furthermore, the sectorial lorentz symmetry may be only a low - energy limit, in the same way as the relation $ \ omega $ ( frequency ) = $ c _ s $ ( speed of sound ) $ k $ ( wave vector ) holds for low - energy phonons in a crystal. in this context, phenomena such as the absence of greisen - zatsepin - kuzmin cutoff for protons and nuclei and the stability of unstable particles ( e. g. neutron, several nuclei... ) at very high energy are basic properties of a wide class of noncausal models where local lorentz invariance is broken introducing a fundamental length. observable phenomena are expected at very short wavelength scales, even if lorentz symmetry violation remains invisible to standard low - energy tests. we present a detailed discussion of the implications of lorentz symmetry violation for very high - energy nuclear physics. | arxiv:nucl-th/9708028 |
we study the properties of low - column density gas clumps in the halo of the milky way based on high - resolution 21 - cm observations. using interferometric data from the wsrt and the vla we study hi emission at low -, intermediate - and high radial velocities along four lines of sight towards quasars. along these sightlines we previously detected weak caii and nai absorbers in their optical spectra. the analysis of the high - resolution hi data reveals the presence of several compact and cold clumps of neutral gas at velocities similar to the optical absorption. the clumps have narrow hi line widths in the range of 1. 8 to 13 km / s, yielding upper limits for the kinetic temperature of the gas of 70 to 3700 k. the neutral gas has low hi column densities in the range of 5e18 to 3e19 1 / cm ^ 2. all clumps have angular sizes of only a few arcminutes. our high - resolution 21 - cm observations indicate that many of the caii and nai absorbers seen in our optical quasar spectra are associated with low - column density hi clumps at small angular scales. this suggests that next to the massive, high - column density neutral gas clouds in the halo ( the common 21 - cm lvcs, ivcs, and hvcs ) there exists a population of low - mass, neutral gas structures in the halo that remain mostly unseen in the existing 21 - cm all - sky surveys of ivcs and hvcs. the estimated thermal gas pressures of the detected hi clumps are consistent with what is expected from theoretical models of gas in the inner and outer milky way halo. | arxiv:0907.0171 |
bulk energization of electrons to $ 10 \, - \, 20 \, $ kev in solar flares is attributed to dissipation of alfv \ ' en waves that transport energy and potential downward to an acceleration region near the chromosphere. the acceleration involves the parallel electric field that develops in the limit of inertial alfv \ ' en waves ( iaws ). a two - potential model for iaws is used to relate the parallel potential to the cross - field potential transported by the waves. we identify a maximum parallel potential in terms of a maximum current density that corresponds to the threshold for the onset of anomalous resistivity. this maximum is of order $ 10 \, $ kv when the threshold is that for the buneman instability. we argue that this restricts the cross - field potential in an alfv \ ' en wave to about $ 10 \, $ kv. effective dissipation requires a large number of up - and down - current paths associated with multiple alfv \ ' en waves. the electron acceleration occurs in localized, transient, anomalously - conducting regions ( ltacrs ) and is associated with the parallel electric field determined by ohm ' s law with an anomalous resistivity. we introduce an idealized model in which the ltacrs are ( upward - ) current sheets, a few skin depths in thickness, separated by much - larger regions of weaker return current. we show that this model can account semi - quantitatively for bulk energization. | arxiv:1307.7772 |
the crossover between ideal josephson behavior and uniform superconducting flow is studied by solving exactly the ginzburg - landau equation for a one - dimensional superconductor in the presence of an effective delta function potential of arbitrary strength. as the effective scattering is turned off, the pairs of josephson solutions with equal current evolve into a uniform and a solitonic solution with nonzero phase offset. it is also argued that a microscopic description of the crossover must satisfy the self - consistency condition, which is shown to guarantee current conservation. the adiabatic response to an external bias is briefly described. the ac josephson effect is shown to break down when the external voltage is applied at points which are sufficiently far from the junction. | arxiv:cond-mat/9312005 |
a decomposition theorem is established for a class of closed riemannian submanifolds immersed in a space form of constant sectional curvature. in particular, it is shown that if $ m $ has nonnegative sectional curvature and admits a codazzi tensor with " parallel mean curvature ", then $ m $ is locally isometric to a direct product of irreducible factors determined by the spectrum of that tensor. this decomposition is global when $ m $ is simply connected, and generalizes what is known for immersed submanifolds with parallel mean curvature vector. | arxiv:2004.03103 |
the future 6g - enabled iot will facilitate seamless global connectivity among ubiquitous wireless devices, but this advancement also introduces heightened security risks such as spoofing attacks. physical - layer authentication ( pla ) has emerged as a promising, inherently secure, and energy - efficient technique for authenticating iot terminals. nonetheless, the direct application of state - of - the - art pla schemes to 6g - enabled iot encounters two major hurdles : inaccurate channel fingerprints and the inefficient utilization of prior fingerprint information. to tackle these challenges, we leverage reconfigurable intelligent surfaces ( riss ) to enhance fingerprint accuracy. additionally, we integrate active learning and gaussian processes ( gps ) to propose an efficient gaussian process classification ( egpc ) - based pla scheme, aiming for reliable and lightweight authentication. following bayes ' theorem, we model configurable fingerprints using gps and employ the expectation propagation method to identify unknown fingerprints. given the difficulty of obtaining sufficient labeled fingerprint samples to train pla models, we propose three fingerprint selection algorithms. these algorithms select unlabeled fingerprints and query their identities using upper - layer authentication mechanisms. among these methods, the optimal algorithm reduces the number of training fingerprints needed through importance sampling and eliminates the requirement for pla model retraining through joint distribution calculation. simulations results reveal that, in comparison with non - ris - based approaches, the ris - aided pla framework decreases the authentication error rate by 98. 69 %. in addition, our designed fingerprint selection algorithms achieve a reduction in the authentication error rate of up to 86. 93 % compared to baseline active learning schemes. | arxiv:2307.12263 |
dialogue state tracking ( dst ), which is the process of inferring user goals by estimating belief states given the dialogue history, plays a critical role in task - oriented dialogue systems. a coreference phenomenon observed in multi - turn conversations is not addressed by existing dst models, leading to sub - optimal performances. in this paper, we propose coreference dialogue state tracker ( cdst ) that explicitly models the coreference feature. in particular, at each turn, the proposed model jointly predicts the coreferred domain - slot pair and extracts the coreference values from the dialogue context. experimental results on multiwoz 2. 1 dataset show that the proposed model achieves the state - of - the - art joint goal accuracy of 56. 47 %. | arxiv:2106.08723 |
high - level synthesis ( hls ) frameworks allow to easily specify a large number of variants of the same hardware design by only acting on optimization directives. nonetheless, the hardware synthesis of implementations for all possible combinations of directive values is impractical even for simple designs. addressing this shortcoming, many hls design space exploration ( dse ) strategies have been proposed to devise directive settings leading to high - quality implementations while limiting the number of synthesis runs. all these works require considerable efforts to validate the proposed strategies and / or to build the knowledge base employed to tune abstract models, as both tasks mandate the syntheses of large collections of implementations. currently, such data gathering is performed ad - hoc, a ) leading to a lack of standardization, hampering comparisons between dse alternatives, and b ) posing a very high burden to researchers willing to develop novel dse strategies. against this backdrop, we here introduce db4hls, a database of exhaustive hls explorations comprising more than 100000 design points collected over 4 years of synthesis time. the open structure of db4hls allows the incremental integration of new dses, which can be easily defined with a dedicated domain - specific language. we think that of our database, available at https : / / www. db4hls. inf. usi. ch /, will be a valuable tool for the research community investigating automated strategies for the optimization of hls - based hardware designs. | arxiv:2101.00587 |
we have studied statistical mechanics of a gas of vortices in two dimensions. we introduce a new observable - - - a condensate fraction of onsager vortices - - - to quantify the emergence of the vortex condensate. the condensation of onsager vortices is most transparently observed in a single vortex species system and occurs due to a competition between solid body rotation ( c. f. vortex lattice ) and potential flow ( c. f. multiple quantum vortex state ). we propose an experiment to observe the condensation transition of the vortices in such a single vortex species system. | arxiv:1612.02930 |
we prove a conjecture by w. bergweiler and a. eremenko on the traces of elements of modular group in this paper | arxiv:1204.5930 |
in industrial recommendation systems on websites and apps, it is essential to recall and predict top - n results relevant to user interests from a content pool of billions within milliseconds. to cope with continuous data growth and improve real - time recommendation performance, we have designed and implemented a high - performance batch query architecture for real - time recommendation systems. our contributions include optimizing hash structures with a cacheline - aware probing method to enhance coalesced hashing, as well as the implementation of a hybrid storage key - value service built upon it. our experiments indicate this approach significantly surpasses conventional hash tables in batch query throughput, achieving up to 90 % of the query throughput of random memory access when incorporating parallel optimization. the support for nvme, integrating two - tier storage for hot and cold data, notably reduces resource consumption. additionally, the system facilitates dynamic updates, automated sharding of attributes and feature embedding tables, and introduces innovative protocols for consistency in batch queries, thereby enhancing the effectiveness of real - time incremental learning updates. this architecture has been deployed and in use in the bilibili recommendation system for over a year, a video content community with hundreds of millions of users, supporting 10x increase in model computation with minimal resource growth, improving outcomes while preserving the system ' s real - time performance. | arxiv:2409.00400 |
the compressible navier - stokes - poisson ( nsp ) system is considered in $ r ^ 3 $ in the present paper and the influences of the electric field of the internal electrostatic potential force governed by the self - consistent poisson equation on the qualitative behaviors of solutions is analyzed. it is observed that the rotating effect of electric field affects the dispersion of fluids and reduces the time decay rate of solutions. indeed, we show that the density of the nsp system converges to its equilibrium state at the same $ l ^ 2 $ - rate $ ( 1 + t ) ^ { - \ frac34 } $ or $ l ^ \ infty $ - rate $ ( 1 + t ) ^ { - 3 / 2 } $ respectively as the compressible navier - stokes system, but the momentum of the nsp system decays at the $ l ^ 2 $ - rate $ ( 1 + t ) ^ { - \ frac14 } $ or $ l ^ \ infty $ - rate $ ( 1 + t ) ^ { - 1 } $ respectively, which is slower than the $ l ^ 2 $ - rate $ ( 1 + t ) ^ { - \ frac34 } $ or $ l ^ \ infty $ - rate $ ( 1 + t ) ^ { - 3 / 2 } $ for the compressible navier - stokes system. these convergence rates are also shown to be optimal for the compressible nsp system. | arxiv:0811.3788 |
model - free reinforcement learning has emerged as a powerful method for developing robust robot control policies capable of navigating through complex and unstructured terrains. the effectiveness of these methods hinges on two essential elements : ( 1 ) the use of massively parallel physics simulations to expedite policy training, and ( 2 ) an environment generator tasked with crafting sufficiently challenging yet attainable terrains to facilitate continuous policy improvement. existing methods of environment generation often rely on heuristics constrained by a set of parameters, limiting the diversity and realism. in this work, we introduce the adaptive diffusion terrain generator ( adtg ), a novel method that leverages denoising diffusion probabilistic models to dynamically expand existing training environments by adding more diverse and complex terrains adaptive to the current policy. adtg guides the diffusion model ' s generation process through initial noise optimization, blending noise - corrupted terrains from existing training environments weighted by the policy ' s performance in each corresponding environment. by manipulating the noise corruption level, adtg seamlessly transitions between generating similar terrains for policy fine - tuning and novel ones to expand training diversity. our experiments show that the policy trained by adtg outperforms both procedural generated and natural environments, along with popular navigation methods. | arxiv:2410.10766 |
self - interacting dark matter ( sidm ) models have the potential to solve the small - scale problems that arise in the cold dark matter paradigm. simulations are a powerful tool for studying sidm in the context of astrophysics, but it is numerically challenging to study differential cross - sections that favour small - angle scattering, as in light - mediator models. here, we present a novel approach to model frequent scattering based on an effective drag force, which we have implemented into the n - body code gadget - 3. in a range of test problems, we demonstrate that our implementation accurately models frequent scattering. our implementation can be used to study differences between sidm models that predict rare and frequent scattering. we simulate core formation in isolated dark matter haloes, as well as major mergers of galaxy clusters and find that sidm models with rare and frequent interactions make different predictions. in particular, frequent interactions are able to produce larger offsets between the distribution of galaxies and dark matter in equal - mass mergers. | arxiv:2012.10277 |
professionals are qualified to perform the role of or interact with engineering geologists. their primary focus, however, is the use of engineering geology data, as well as engineering skills to : design advanced exploration programs, environmental management or remediation projects including : groundwater extraction and sustainability, natural hazard mitigation systems, energy resource exploration and extraction, mineral resource exploration and extraction, and environmental remediation. design infrastructure, including : surface works, foundations, tunnels, dams, caverns, and other construction that interfaces with the ground. oversee components of mining including : advanced resource assessment and economics, mineral processing, mine planning, and geomechanical and geotechnical stability. in all these activities, the geological model, geological history, and environment, as well as measured engineering properties of relevant earth materials are critical to engineering design and decision making. = = references = = = = see also = = civil engineering engineering geology geology environmental engineering mining engineering petroleum engineering | https://en.wikipedia.org/wiki/Geological_engineering |
because of the huge number of graphs possible even with a small number of nodes, inference on network structure is known to be a challenging problem. generating large random directed graphs with prescribed probabilities of occurrences of some meaningful patterns ( motifs ) is also difficult. we show how to generate such random graphs according to a formal probabilistic representation, using fast markov chain monte carlo methods to sample them. as an illustration, we generate realistic graphs with several hundred nodes mimicking a gene transcription interaction network in escherichia coli. | arxiv:1311.6443 |
we present a general theory of potentials that support bound states at positive energies ( bound states in the continuum ). on the theoretical side, we prove that, for systems described by nonlocal potentials of the form $ v ( r, r ' ) $, bound states at positive energies are as common as those at negative energies. at the same time, we show that a local potential of the form $ v ( r ) $ rarely supports a positive energy bound state. on the practical side, we show how to construct a ( naturally nonlocal ) potential which supports an arbitrary normalizable state at an arbitrary positive energy. we demonstrate our theory with numerical examples both in momentum and coordinate spaces with emphasis on the important role played by nonlocal potentials. finally, we discuss how to observe bound states at positive energies, and where to search for nonlocal potentials which may support them. | arxiv:2410.09647 |
we construct a two - current model. it includes two gauge fields, which introduce the doping effect, and a neutral scalar field. and then we numerically construct an ads black brane geometry with scalar hair. over this background, we study the fermionic system with the pseudoscalar yukawa coupling. some universal properties from the pseudoscalar yukawa coupling are revealed. in particular, as the coupling increases, there is a transfer of the spectral weight from the low energy band to the high energy band. the transfer is over low energy scales but not over all energy scales. the peculiar properties are also explored. the study shows that with the increase of the doping, the gap opens more difficult. it indicates that there is a competition between the pseudoscalar yukawa coupling and the doping. | arxiv:2002.03343 |
we showed in previous work that for homogeneous yang - baxter ( yb ) deformations of ads $ _ 5 \ times $ s $ ^ 5 $, the open string metric and coupling, and as a result the closed string density $ e ^ { - 2 \ phi } \ sqrt { g } $, remain undeformed. in this work, in addition to extending these results to the deformation associated with the modified cybe, or $ \ eta $ - deformation, we identify the page forms as the open string counterpart for rr fields and demonstrate case by case that the non - zero page forms remain invariant under yb deformations. we give a physical meaning to the killing vector $ i $ of generalized supergravity and show for all yb deformations : 1 ) $ i $ appears as a current for center of mass motion on the worldvolume of a d - branes probing the background, 2 ) $ i $ is equal to the divergence of the noncommutativity parameter, 3 ) $ i $ exhibits " holographic " behavior, where the radial component of $ i $ vanishes at the ads boundary, and 4 ) in pure spinor formalism $ i $ is related to a certain state in the brst cohomology. | arxiv:1708.03163 |
the field of scattering amplitudes plays a central role in elementary - particle physics. this includes various problems of broader interest for collider physics, gravitational physics, and fundamental principles underlying quantum field theory. we describe various applications and theoretical advances pointing towards novel descriptions of quantum field theories. comments on future prospects are included. | arxiv:2210.03146 |
with the calculations, possess increased stability. one of the three mutations shifts the population in favor of the higher order oligomerization state in solution as shown by both size exclusion chromatography and native gel electrophoresis. a in silico method, poredesigner, was developed to redesign bacterial channel protein ( ompf ) to reduce its 1 nm pore size to any desired sub - nm dimension. transport experiments on the narrowest designed pores revealed complete salt rejection when assembled in biomimetic block - polymer matrices. = = see also = = = = references = = = = external links = = servers for protein engineering and related topics based on the what if software enzymes built from scratch – researchers engineer never - before - seen catalysts using a new computational technique, technology review, march 10, 2008 | https://en.wikipedia.org/wiki/Protein_engineering |
as the fano effect is an interference phenomenon where tunneling paths compete for the electronic transport, it becomes a probe to catch fingerprints of majorana fermions lying on condensed matter systems. in this work we benefit of this mechanism by proposing as a route for that an aharonov - bohm - like interferometer composed by two quantum dots, being one of them coupled to a majorana bound state, which is attached to one of the edges of a semi - infinite kitaev wire within the topological phase. by changing the fermi energy of the leads and the symmetric detuning of the levels for the dots, we show that opposing fano regimes result in a transmittance characterized by distinct conducting and insulating regions, which are fingerprints of an isolated majorana quasiparticle. furthermore, we show that the maximum fluctuation of the transmittance as a function of the detuning is half for a semi - infinite wire, while it corresponds to the unity for a finite system. the setup proposed here constitutes an alternative experimental tool to detect majorana excitations. | arxiv:1408.0454 |
cross - application interference can affect drastically performance of hpc applications when running in clouds. this problem is caused by concurrent access performed by co - located applications to shared and non - sliceable resources such as cache and memory. in order to address this issue, some works adopted a qualitative approach that does not take into account the amount of access to shared resources. in addition, a few works, even considering the amount of access, evaluated just the sllc access contention as the root of this problem. however, our experiments revealed that interference is intrinsically related to the amount of simultaneous access to shared resources, besides showing that another shared resources, apart from sllc, can also influence the interference suffered by co - located applications. in this paper, we present a quantitative model for predicting cross - application interference in virtual environments. our proposed model takes into account the amount of simultaneous access to sllc, dram and virtual network, and the similarity of application ' s access burden to predict the level of interference suffered by applications when co - located in a same physical machine. experiments considering a real petroleum reservoir simulator and applications from hpcc benchmark showed that our model reached an average and maximum prediction errors around 4 \ % and 12 \ %, besides achieving an error less than 10 \ % in approximately 96 \ % of all tested cases. | arxiv:1610.04309 |
we give a counterexample to a conjecture of d. h. gottlieb and prove a strengthened version of it. the conjecture says that a map from a finite cw - complex x to an aspherical cw - complex y with non - zero euler characteristic can have non - trivial degree ( suitably defined ) only if the centralizer of the image of the fundamental group of x is trivial. as a corollary we show that in the above situation all components of non - zero degree maps in the space of maps from x to y are contractible. | arxiv:math/0702826 |
the alpha decay parameter in the process omega - minus - > lambda + k - minus has been measured from a sample of 4. 50 million unpolarized omega - minus decays recorded by the hypercp ( e871 ) experiment at fermilab and found to be [ 1. 78 + / - 0. 19 ( stat ) + / - 0. 16 ( syst ) ] { \ times } 10 ^ { - 2 }. this is the first unambiguous evidence for a nonzero alpha decay parameter, and hence parity violation, in the omega - minus - > lambda + k - minus decay. | arxiv:hep-ex/0505010 |
nowadays, as the quantity of data to process began to rise, so did the need for a method to discern what pieces of information could be useful for the user ; in response, researchers focused their efforts on improving the already existing ranking methods or creating new ones starting from them. this survey will be presented a small list of some of the most known and / or most recent solutions proposed, with some possible applications for them, concerning a state of the art restricted to around the last ten years, comparing their performance with the traditional one top - k and skyline queries. | arxiv:2203.00331 |
the increasing number of scientific publications in acoustics, in general, presents difficulties in conducting traditional literature surveys. this work explores the use of a generative pre - trained transformer ( gpt ) model to automate a literature survey of 116 articles on data - driven speech enhancement methods. the main objective is to evaluate the capabilities and limitations of the model in providing accurate responses to specific queries about the papers selected from a reference human - based survey. while we see great potential to automate literature surveys in acoustics, improvements are needed to address technical questions more clearly and accurately. | arxiv:2310.06260 |
by using a weak measurement technique, we investigated the interplay between the angular and lateral goos - haenchen shift of a focused he - ne laser beam for incidence near the critical angle. we verified that this interplay dramatically affects the composite goos - haenchen shift of the propagated beam. the experimental results confirm theoretical predictions that recently appeared in the literature. | arxiv:1608.07528 |
cine magnetic resonance imaging ( mri ) allows for understanding of the heart ' s function and condition in a non - invasive manner. undersampling of the $ k $ - space is employed to reduce the scan duration, thus increasing patient comfort and reducing the risk of motion artefacts, at the cost of reduced image quality. in this challenge paper, we investigate the use of a convolutional recurrent neural network ( crnn ) architecture to exploit temporal correlations in supervised cine cardiac mri reconstruction. this is combined with a single - image super - resolution refinement module to improve single coil reconstruction by 4. 4 \ % in structural similarity and 3. 9 \ % in normalised mean square error compared to a plain crnn implementation. we deploy a high - pass filter to our $ \ ell _ 1 $ loss to allow greater emphasis on high - frequency details which are missing in the original data. the proposed model demonstrates considerable enhancements compared to the baseline case and holds promising potential for further improving cardiac mri reconstruction. | arxiv:2309.13385 |
we discuss level schemes of small quantum - dot turnstiles and their applicability in the production of entanglement in two - photon emission. due to the large energy splitting of the single - electron levels, only one single electron level and one single hole level can be made resonant with the levels in the conduction band and valence band. this results in a model with nine distinct levels, which are split by the coulomb interactions. we show that the optical selection rules are different for flat and tall cylindrically symmetric dots, and how this affects the quality of the entanglement generated in the decay of the biexciton state. the effect of charge carrier tunneling and of a resonant cavity is included in the model. | arxiv:quant-ph/0210170 |
in accordance with the electroweak theory, we perform, in the first - born approximation, a detailed analytical treatment of the differential cross - section ( dcs ) for the elastic scattering process $ e ^ { - } + \ nu _ { \ mu } \ longrightarrow e ^ { - } + \ nu _ { \ mu } $ in both absence and presence of a circularly polarized laser field. this scattering process is examined by using dirac - volkov wave functions for charged particles within an external laser field. the theoretical results obtained for the differential cross - section without laser field are compared with other theoretical results within the framework of fermi theory. these results revealed to us the most important points that contribute to the understanding of the electroweak theory role in solving the problem of unitarity violation of the differential cross - section in fermi theory. the differential cross section is modified significantly by inserting the electrons into an electromagnetic field. in addition, the influence of the laser strength and its frequency on the photons exchange between the colliding system and the laser field are also included and discussed. these effects are heavily related to the order and argument of the ordinary bessel functions introduced in the theoretical calculation. | arxiv:2203.14955 |
fr \ ' echet regression extends linear regression to model complex responses in metric spaces, making it particularly relevant for multi - label regression, where eachinstance can have multiple associated labels. however, addressing noise and dependencies among predictors within this framework remains un derexplored. in this paper, we present an extension of the global fr \ ' echet re gression model that enables explicit modeling of relationships between input variables and multiple responses. to address challenges arising from noise and multicollinearity, we propose a novel framework based on implicit regu larization, which preserves the intrinsic structure of the data while effectively capturing complex dependencies. our approach ensures accurate and efficient modeling without the biases introduced by traditional explicit regularization methods. theoretical guarantees are provided, and the performance of the proposed method is demonstrated through numerical experiments. | arxiv:2412.18247 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.