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mobile crowdsourcing ( mcs ) is the generalized act of outsourcing sensing tasks, traditionally performed by employees or contractors, to a large group of smart - phone users by means of an open call. with the increasing complexity of the crowdsourcing applications, requesters find it essential to harness the power of collaboration among the workers by forming teams of skilled workers satisfying their complex tasks ' requirements. this type of mcs is called collaborative mcs ( cmcs ). previous cmcs approaches have mainly focused only on the aspect of team skills maximization. other team formation studies on social networks ( sns ) have only focused on social relationship maximization. in this paper, we present a hybrid approach where requesters are able to hire a team that, not only has the required expertise, but also is socially connected and can accomplish tasks collaboratively. because team formation in cmcs is proven to be np - hard, we develop a stochastic algorithm that exploit workers knowledge about their sn neighbors and asks a designated leader to recruit a suitable team. the proposed algorithm is inspired from the optimal stopping strategies and uses the odds - algorithm to compute its output. experimental results show that, compared to the benchmark exponential optimal solution, the proposed approach reduces computation time and produces reasonable performance results. | arxiv:2004.13881 |
recent advances in generative adversarial networks ( gans ) have led to the creation of realistic - looking digital images that pose a major challenge to their detection by humans or computers. gans are used in a wide range of tasks, from modifying small attributes of an image ( stargan [ 14 ] ), transferring attributes between image pairs ( cyclegan [ 91 ] ), as well as generating entirely new images ( progan [ 36 ], stylegan [ 37 ], spade / gaugan [ 64 ] ). in this paper, we propose a novel approach to detect, attribute and localize gan generated images that combines image features with deep learning methods. for every image, co - occurrence matrices are computed on neighborhood pixels of rgb channels in different directions ( horizontal, vertical and diagonal ). a deep learning network is then trained on these features to detect, attribute and localize these gan generated / manipulated images. a large scale evaluation of our approach on 5 gan datasets comprising over 2. 76 million images ( progan, stargan, cyclegan, stylegan and spade / gaugan ) shows promising results in detecting gan generated images. | arxiv:2007.10466 |
the ovi $ \ lambda \ lambda $ 1032, 1038 \ aa \ doublet emission traces collisionally ionized gas with $ t \ approx 10 ^ { 5. 5 } $ k, where the cooling curve peaks for metal - enriched plasma. this warm - hot phase is usually not well - resolved in numerical simulations of the multiphase interstellar medium ( ism ), but can be responsible for a significant fraction of the emitted energy. comparing simulated ovi emission to observations is therefore a valuable test of whether simulations predict reasonable cooling rates from this phase. we calculate ovi $ \ lambda $ 1032 \ aa \ emission, assuming collisional ionization equilibrium, for our small - box simulations of the stratified ism regulated by supernovae. we find that the agreement is very good for our solar neighborhood model, both in terms of emission flux and mean ovi density seen in absorption. we explore runs with higher surface densities and find that, in our simulations, the ovi emission from the disk scales roughly linearly with the star formation rate. observations of ovi emission are rare for external galaxies, but our results do not show obvious inconsistency with the existing data. assuming the solar metallicity, ovi emission from the galaxy disk in our simulations accounts for roughly 0. 5 \ % of supernovae heating. | arxiv:1611.00402 |
to validate the molecular description of the observed $ z _ b ( 10610 ) / z _ b ( 10650 ) $ and $ z _ c ( 3900 ) / z _ c ( 4025 ) $, it is valuable to investigate their counterparts, denoted as $ z _ { qv } ^ { ( \ prime ) } $ in this work, and the corresponding decay modes. in this work, we present an analysis of the $ z _ { qv } ^ { ( \ prime ) } $ using flavor symmetry. we also use the effective lagrangian based on the heavy quark symmetry to explore the rescattering mechanism and calculate the partial widths for the isospin conserved channels $ z _ { qv } ^ { ( \ prime ) } \ to \ eta _ q v $. the predicted partial widths are of an order of mev for $ z _ { qv } \ to \ eta _ q v $, which correspond to branching ratios of the order of $ 10 ^ { - 2 } \ sim 10 ^ { - 1 } $. for $ z _ { qv } ^ \ prime \ to \ eta _ q v $, the partial widths are a few hundreds of kev and the branching ratios are about $ 10 ^ { - 3 } $. future experimental measurements can test our predictions on the partial widths and thus examine the molecule description of heavy quarkoniumlike exotic states. | arxiv:1409.0754 |
we present the optical spectroscopic follow - up of 31 z = 0. 3 lyman - alpha ( lya ) emitters, previously identified by deharveng et al. ( 2008 ). we find that 17 % of the lya emitters have line ratios that require the hard ionizing continuum produced by an agn. the uniform dust screen geometry traditionally used in studies similar to ours is not able to simultaneously reproduce the observed high lya / halpha and halpha / hbeta line ratios. we consider different possibilities for the geometry of the dust around the emitting sources. we find that also a uniform mixture of sources and dust does not reproduce the observed line ratios. instead, these are well reproduced by a clumpy dust screen. this more realistic treatment of the geometry results in extinction corrected ( lya / halpha ) _ c values consistent with case b recombination theory, whereas a uniform dust screen model would imply values ( lya / halpha ) _ c higher than 8. 7. our analysis shows that there is no need to invoke " ad - hoc " multi phase media in which the lya photons only scatter between the dusty clouds and eventually escape. | arxiv:0909.3847 |
this paper studies the optimal transmission switching ( ots ) problem for power systems, where certain lines are fixed ( uncontrollable ) and the remaining ones are controllable via on / off switches. the goal is to identify a topology of the power grid that minimizes the cost of the system operation while satisfying the physical and operational constraints. most of the existing methods for the problem are based on first converting the ots into a mixed - integer linear program ( milp ) or mixed - integer quadratic program ( miqp ), and then iteratively solving a series of its convex relaxations. the performance of these methods depends heavily on the strength of the milp or miqp formulations. in this paper, it is shown that finding the strongest variable upper and lower bounds to be used in an milp or miqp formulation of the ots based on the big - $ m $ or mccormick inequalities is np - hard. furthermore, it is proven that unless p = np, there is no constant - factor approximation algorithm for constructing these variable bounds. despite the inherent difficulty of obtaining the strongest bounds in general, a simple bound strengthening method is presented to strengthen the convex relaxation of the problem when there exists a connected spanning subnetwork of the system with fixed lines. the proposed method can be treated as a preprocessing step that is independent of the solver to be later used for numerical calculations and can be carried out offline before initiating the solver. a remarkable speedup in the runtime of the mixed - integer solvers is obtained using the proposed bound strengthening method for medium - and large - scale real - world systems. | arxiv:1711.10428 |
we show that the charge accumulated by a dielectric plasma - facing solid can be measured by infrared spectroscopy. the approach utilizes a stack of materials supporting a surface plasmon resonance in the infrared. for frequencies near the berreman resonance of the layer facing the plasma the reflectivity dip - - measured from the back of the stack, not in contact with the plasma - - depends strongly on the angle of incidence making it an ideal sensor for the changes of the layer ' s dielectric function due to the polarizability of the trapped surplus charges. the charge - induced shifts of the dip, both as a function of the angle and the frequency of the incident infrared light, are large enough to be measurable by attenuated total reflection setups. | arxiv:1809.03296 |
it has been suggested to use the production of lambda hyperons for investigating the nucleon spin structure. the viability of this idea depends crucially on the spin structure of the lambda. using nonperturbatively o ( a ) improved wilson fermions in the quenched approximation we have studied matrix elements of two - quark operators in the lambda. we present results for the axial vector current, which give us the contributions of the u, d, and s quarks to the lambda spin. | arxiv:hep-lat/0110057 |
we are going to study the dynamical properties of the rational semigroup $ q _ { t } ( \ mu ) $ where $ q _ { t } ( \ mu ) = ( 1 - t ) \ mu * ( 1 - t \ mu ) ^ { - 1 }, $ for $ t \ in [ 0, 1 ) $, that is defined for $ \ mu \ in \ mathcal { p } ( g ) $, the set of borel probabilities over $ ( g, \ cdot ) $ an abelian compact topological group where we define the \ textbf { convolution }, $ \ nu * \ mu \ in \ mathcal { p } ( g ) $, as usual for a group $ \ int f d ( \ nu * \ mu ) = \ int \ int f ( xy ) d \ nu ( x ) d \ mu ( y ), $ then $ ( \ mathcal { p } ( g ), * ) $ became a $ \ textbf { convolution measure algebra } $ ( cm - algebra ). we investigate several properties for this semigroup ( as the stable manifold theorem, asymptotic behavior, invariant sets, differential properties, stationary points, etc ) and how they are related with the choquet - deny equation. as an application we give a complete description of this semigroup for finite abelian groups. | arxiv:1411.4177 |
we examine string field algebra which is generated by star product in witten ' s string field theory including ghost part. we perform calculations using oscillator representation consistently. we construct wedge like states in ghost part and investigate algebras among them. as a by - product we have obtained some solutions of vacuum string field theory. we also discuss some problems about identity state. we hope these calculations will be useful for further investigation of witten type string field theory. | arxiv:hep-th/0110124 |
target characterization is an important step in many defense missions, often relying on fitting a known target model to observed data. optimization of model parameters can be computationally expensive depending on the model complexity, thus having models that both describe the data well and that can be efficiently optimized is critical. this work introduces a class of radar models that can be used to represent the radar scattering response of a target at high frequencies while also enabling the use of gradient - based optimization. | arxiv:2206.02075 |
transfer learning ( tl ) approaches have shown promising results when handling tasks with limited training data. however, considerable memory and computational resources are often required for fine - tuning pre - trained neural networks with target domain data. in this work, we introduce a novel method for leveraging pre - trained models for low - resource ( music ) classification based on the concept of neural model reprogramming ( nmr ). nmr aims at re - purposing a pre - trained model from a source domain to a target domain by modifying the input of a frozen pre - trained model. in addition to the known, input - independent, reprogramming method, we propose an advanced reprogramming paradigm : input - dependent nmr, to increase adaptability to complex input data such as musical audio. experimental results suggest that a neural model pre - trained on large - scale datasets can successfully perform music genre classification by using this reprogramming method. the two proposed input - dependent nmr tl methods outperform fine - tuning - based tl methods on a small genre classification dataset. | arxiv:2211.01317 |
in the absence of any additional assumption it is natural to conjecture that sizeable flavour - mixing mass entries, $ \ delta m ^ 2 $, may appear in the mass matrices of the scalars of the mssm, i. e. $ \ delta m ^ 2 \ sim o ( m ^ 2 ) $. this flavour violation can still be reconciled with the experiment if the gaugino mass, $ m _ { 1 / 2 } $, is large enough, leading to a { \ em gaugino dominance } framework ( i. e. $ m _ { 1 / 2 } ^ 2 \ gg m ^ 2 $ ), which permits a remarkably model - - independent analysis. we study this possibility focussing our attention on the $ \ mu \ rightarrow e, \ gamma $ decay. in this way we obtain very strong and general constraints, in particular $ \ frac { m _ { 1 / 2 } ^ 2 } { \ delta m } \ simgt 34 \ { \ rm tev } $. on the other hand, we show that our analysis and results remain valid for values of $ m ^ 2 $ much larger than $ \ delta m ^ 2 $, namely for $ \ frac { \ delta m ^ 2 } { m ^ 2 } \ simgt \ frac { m ^ 2 } { 10 \ { \ rm tev ^ 2 } } $, thus extending enormously their scope of application. finally, we discuss the implications for superstring scenarios. | arxiv:hep-ph/9507377 |
the supremum of reduction numbers of ideals having principal reductions is expressed in terms of the integral degree, a new invariant of the ring, which is finite provided the ring has finite integral closure. as a consequence, one obtains bounds for the castelnuovo - mumford regularity of the rees algebra and for the artin - rees numbers. | arxiv:0706.3381 |
the present work is focused on the investigation of the existence of compact structures describing anisotropic matter distributions within the framework of modified gravity theories, specifically f ( r, $ \ mathcal { t } $ ) gravity theory. additionally, we have taken f ( r, $ \ mathcal { t } $ ) as a linear function of the ricci scalar $ r $ and the trace of the energy - momentum tensor $ \ mathcal { t } $ as $ f ( r, \ mathcal { t } ) $ = $ r + 2 \ chi \ mathcal { t } $, where $ \ chi $ is a dimensionless coupling parameter, and the lagrangian matter $ \ mathcal { l } _ m = - \ frac { 1 } { 3 } \ left ( 2p _ { t } + p _ { r } \ right ) $, to describe the complete set of field equations for the anisotropic matter distribution. we follow the embedding class one procedure using eisland condition to obtain a full space - time description inside the stellar configuration. once the space - time geometry is specified we determine the complete solution of the modified einstein equations by using the mit bag model equation of state $ p _ { r } = \ frac { 1 } { 3 } \ left ( \ rho - 4b \ right ) $ that describes the strange quark matter ( sqm ) distribution inside the stellar system, where $ b $ denotes a bag constant. the physical validity of our anisotropic solution is confirmed by executing several physical tests. it is worth mentioning that with the help of the observed mass values for the various strange star candidates we have predicted the exact radii by taking different values for $ \ chi $ and $ b $. these predicted radii show monotonic decreasing nature as the parameter $ \ chi $ is moved from $ - 0. 8 $ to $ 0. 8 $ progressively. in this case, our anisotropic stellar system becomes more massive and transforms into more dense compact stars. | arxiv:1907.10149 |
for thermoelectric transport in the presence of a magnetic field that breaks time - reversal symmetry, a strong bound on the onsager coefficients is derived within a general set - up using three terminals. asymmetric onsager coefficients lead to a maximum efficiency substantially smaller than the carnot efficiency reaching only \ eta _ c / 4 in the limit of strong asymmetry. related bounds are derived for efficiency at maximum power, which can become larger than the curzon - ahlborn value \ eta _ c / 2, and for a cooling device. our approach reveals that in the presence of reversible currents the standard analysis based on the positivity of entropy production is incomplete without considering the role of current conservation explicitly. | arxiv:1301.0492 |
given a generator of a bounded analytic semigroup on a hilbert space, we show that the corresponding forward maximal regularity operator commutes with the backward. in particular, for self - adjoint generators the images under the two maximal regularity operators have equal unweighted hilbert space norms. | arxiv:2305.04209 |
biomarkers are often measured in bulk to diagnose patients, monitor patient conditions, and research novel drug pathways. the measurement of these biomarkers often suffers from detection limits that result in missing and untrustworthy measurements. frequently, missing biomarkers are imputed so that down - stream analysis can be conducted with modern statistical methods that cannot normally handle data subject to informative censoring. this work develops an empirical bayes $ g $ - modeling method for imputing and denoising biomarker measurements. we establish superior estimation properties compared to popular methods in simulations and demonstrate the utility of the estimated biomarker measurements for down - stream analysis. | arxiv:2306.07239 |
the phonon thermal transport properties of twisted bi - layer graphene are investigated using lattice dynamics and the boltzmann transport equation. the thermal conductivities of 13. 2 and 21. 8 twisted configurations are 56 % and 36 % lower than the untwisted configuration which has a room temperature thermal conductivity of 2260 w / m - k. the reason for this lower thermal conductivity is unraveled from phonon mode - level analysis made possible through the untwisting of layers. due to a large commensurate unitcell of twisted configuration, the brillouin zone is folded but this folding has no bearing on the phonon scattering phase space. the major impact of twisting is felt by flexural phonons with out - of - plane vibrations via the change in strength of flexural interatomic interactions and since these flexural phonons carry majority of the heat in bilayer graphene ( 65 % at room temperature ), the thermal conductivity is sensitive to layer twisting. our study suggests that twisting will affect thermal transport only for those materials that have a major contribution from flexural phonon modes. | arxiv:2311.02964 |
the last financial and economic crisis demonstrated the dysfunctional long - term effects of aggressive behaviour in financial markets. yet, evolutionary game theory predicts that under the condition of strategic dependence a certain degree of aggressive behaviour remains within a given population of agents. however, as the consequences of the financial crisis exhibit, it would be desirable to change the ' rules of the game ' in a way that prevents the occurrence of any aggressive behaviour and thereby also the danger of market crashes. the paper picks up this aspect. through the extension of the in literature well - known hawk - dove game by a quantum approach, we can show that dependent on entanglement, also evolutionary stable strategies can emerge, which are not predicted by classical evolutionary game theory and where the total economic population uses a non aggressive quantum strategy. | arxiv:0904.2113 |
this paper discusses the role of 2 - d / 3 - d cochlear fluid hydrodynamics in the generation of the large nonlinear dynamical range of the basilar membrane ( bm ) and pressure response, in the decoupling between cochlear gain and tuning, and in the dynamic stabilization of the high - gain bm response in the peak region. the large and closely correlated dependence on stimulus level of the bm velocity and fluid pressure gain ( dong and olson, 2013 ), is consistent with a physiologically - oriented schematization of the outer hair cell ( ohc ) mechanism if two hydrodynamic effects are accounted for : amplification of the differential pressure associated with a focusing phenomenon, and viscous damping at the bm - fluid interface. the predictions of the analytical 2 - d wkb approach are compared to solutions of a 3 - d finite element model, showing that these hydrodynamic phenomena yield stable high - gain response in the peak region and a smooth transition among models with different effectiveness of the active mechanism, mimicking the cochlear nonlinear response over a wide stimulus level range. this study explains how an effectively anti - damping nonlinear ohc force may yield large bm and pressure dynamical ranges along with an almost level - independent admittance. | arxiv:2106.00601 |
the remnant black hole - accretion disk system resulting from binary neutron star mergers has proven to be a promising site for synthesizing the heaviest elements via rapid neutron capture ( r - process ). a critical factor in determining the full r - process pattern in these environments is the neutron richness of the ejecta, which is strongly influenced by neutrino interactions. one key ingredient shaping these interactions is fast neutrino flavor conversions ( ffcs ), which arise due to angular crossings in neutrino distributions and occur on nanosecond timescales. we present the first three - dimensional, in - situ, angle - dependent modeling of ffcs in post - merger disks, implemented within general relativistic magnetohydrodynamics with monte carlo neutrino transport. our results reveal that, by suppressing electron neutrinos, ffcs more efficiently cool the disk and weaken the early thermally driven wind. less re - leptonization due to electron neutrino absorption makes this cooler wind more neutron - rich, producing a more robust r - process at higher latitudes of the outflow. this study underscores the necessity of incorporating ffcs in realistic simulations. | arxiv:2503.23727 |
we provide an explicit way to implement non - abelian spin - orbital - angular - momentum ( soam ) coupling in spinor bose - einstein condensates using magnetic gradient coupling. for a spherical surface trap addressable using high - order hermite - gaussian beams, we show that this system supports various degenerate ground states carrying different total angular momenta $ \ mathbf { j } $, and the degeneracy can be tuned by changing the strength of soam coupling. for weakly interacting spinor condensates with $ f = 1 $, the system supports various meta - ferromagnetic phases and meta - polar states described by quantized total mean angular momentum $ | \ langle \ mathbf { j } \ rangle | $. polar states with $ z _ 2 $ symmetry and thomson lattices formed by defects of spin vortices are also discussed. the system can be used to prepare various stable spin vortex states with nontrivial topology, and serve as a platform to investigate strong - correlated physics of neutral atoms with tunable ground - state degeneracy. | arxiv:1907.02216 |
we develop the local morse theory for a class of non - twice continuously differentiable functionals on hilbert spaces, including a new generalization of the gromoll - meyer ' s splitting theorem and a weaker marino - prodi perturbation type result. they are applicable to a wide range of multiple integrals with quasi - linear elliptic euler equations and systems of higher order. | arxiv:1709.02337 |
we present the results of a radio multi - frequency ( $ \ rm 3 - 340 ~ ghz $ ) study of the blazar 3c ~ 454. 3. after subtracting the quiescent spectrum corresponding to optically thin emission, we found two individual synchrotron self - absorption ( ssa ) features in the wide - band spectrum. the one ssa had a relatively low turnover frequency ( $ \ nu _ { \ rm m } $ ) in the range of $ \ rm 3 - 37 ~ ghz $ ( lower $ \ nu _ { \ rm m } $ ssa spectrum, lss ), and the other one had a relatively high $ \ nu _ { \ rm m } $ of $ \ rm 55 - 124 ~ ghz $ ( higher $ \ nu _ { \ rm m } $ ssa spectrum, hss ). using the ssa parameters, we estimated magnetic field strengths at the surface where optical depth $ \ tau = 1 $. the estimated magnetic field strengths were $ \ rm > 7 ~ mg $ and $ \ rm > 0. 2 ~ mg $ for the lss and hss, respectively. the lss emitting region was magnetically dominated before the june 2014 $ \ gamma $ - ray flare. the quasi - stationary component ( c ), $ \ sim 0. 6 ~ { \ rm mas } $ apart from the 43 ghz radio core, became brighter than the core with decreasing observing frequency, and we found that component c was related to the lss. a decrease in jet width was found near component c. as a moving component, k14 approached component c, and the flux density of the component was enhanced while the angular size decreased. the high intrinsic brightness temperature in the fluid frame was obtained as $ t _ { \ rm b, int } \ approx ( 7. 0 \ pm1. 0 ) \ times 10 ^ { 11 } ~ { \ rm k } $ from the jet component after the 2015 august $ \ gamma $ - ray flare, suggesting that component c is a high - energy emitting region. the observed local minimum of jet width and re - brightening behavior suggest a possible recollimation shock in component c. | arxiv:2306.04888 |
the $ s = 1 $ spinor bose condensate at zero temperature supports ferromagnetic and polar phases that combine magnetic and superfluid ordering. we analyze the topological defects of the polar condensate, correcting previous studies, and show that the polar condensate in two dimensions is unstable at any finite temperature ; instead there is a nematic or paired superfluid phase with algebraic order in $ \ exp ( 2 i \ theta ) $, where $ \ theta $ is the superfluid phase, and no magnetic order. the kosterlitz - thouless transition out of this phase is driven by unbinding of half - vortices ( the spin - disordered version of the combined spin and phase defects found by zhou ), and the anomalous universal $ 8 t _ c / \ pi $ stiffness jump at the transition is confirmed in numerical simulations. the anomalous stiffness jump is a clear experimental signature of this phase and the corresponding phase transition. | arxiv:cond-mat/0605102 |
recently, we have shown how a colored - noise langevin equation can be used in the context of molecular dynamics as a tool to obtain dynamical trajectories whose properties are tailored to display desired sampling features. in the present paper, after having reviewed some analytical results for the stochastic differential equations forming the basis of our approach, we describe in detail the implementation of the generalized langevin equation thermostat and the fitting procedure used to obtain optimal parameters. we discuss in detail the simulation of nuclear quantum effects, and demonstrate that, by carefully choosing parameters, one can successfully model strongly anharmonic solids such as neon. for the reader ' s convenience, a library of thermostat parameters and some demonstrative code can be downloaded from an on - line repository. | arxiv:1204.0822 |
we explore the astrobiological significance of f - type stars of spectral type between f5 v and f9. 5 v, which possess jupiter - type planets within or close to their climatological habitable zones. these planets, or at least a subset of those, may also possess rocky exomoons, which potentially offer habitable environments. our work considers eight selected systems. the jupiter - type planets in these systems are in notably differing orbits with eccentricities between 0. 08 ( about mars ) and 0. 72. we consider the stellar uv environments provided by the photospheric stellar radiation, which allows us to compute the uv habitable zones for the systems. following previous studies, dna is taken as a proxy for carbon - based macromolecules following the paradigm that extraterrestrial biology might be based on hydrocarbons. we found that the damage inflicted on dna is notably different for the range of systems studied, and also varies according to the orbit of the jupiter - type planet, especially for systems of high ellipticity, as expected. for some systems excessive values of damage are attained compared to today ' s earth or during the archean eon. considering that the detection of exomoons around different types of stars will remain challenging in the foreseeable future, we view our work also as an example and template for investigating the combined requirements of climatological and uv - based habitability for exosolar objects. | arxiv:1503.02560 |
let g be a simple ( i. e., no loops and no multiple edges ) graph. we investigate the question of how to modify g combinatorially to obtain a sequentially cohen - macaulay graph. we focus on modifications given by adding configurations of whiskers to g, where to add a whisker one adds a new vertex and an edge connecting this vertex to an existing vertex in g. we give various sufficient conditions and necessary conditions on a subset s of the vertices of g so that the graph g \ cup w ( s ), obtained from g by adding a whisker to each vertex in s, is a sequentially cohen - macaulay graph. for instance, we show that if s is a vertex cover of g, then g \ cup w ( s ) is a sequentially cohen - macaulay graph. on the other hand, we show that if g \ backslash s is not sequentially cohen - macaulay, then g \ cup w ( s ) is not a sequentially cohen - macaulay graph. our work is inspired by and generalizes a result of villarreal on the use of whiskers to get cohen - macaulay graphs. | arxiv:math/0605487 |
in the muon storage rings the muons are subject to a very large radial acceleration. the equivalence principle implies a large gravity force. it has no effect on the muon lifetime. | arxiv:1508.02339 |
we present results from a study of 94 red giant stars in the globular cluster m53. we use low - resolution spectra to measure the strength of cn and ch features at $ \ sim $ 3800 and 4300 \ r { a }, respectively. the strengths of these features are used to classify stars into a cn - enhanced and cn - normal population and to measure c and n abundances in all 94 stars. we find the red giant branch stars to be evenly split between the two populations identified, and observe the presence of cn - enhanced stars on the asymptotic giant branch. in addition, we identify 5 ch star candidates based on the strength of their cn and ch band features, and the presence of a p - branch in their ch band. we compare our identification of multiple populations to those based on the na - o anti - correlation and pseudo - color indices in hst uv photometry, and find general agreement between all three methods. our large sample size also allows us to study the radial distribution of each population, and we find that the cn - enhanced population is more centrally concentrated. we use our c and n measurements to compare the evolutionary changes in these elements as a function of magnitude between the two populations, and show that both populations experience similar evolutionary changes to the surface abundances of c and n. finally, we calculate c + n + o abundances for each population and compare them to similar measurements made in m10 ; we find that in both clusters cn - enhanced stars have a slightly enhanced c + n + o ( $ \ delta $ ( c + n + o ) $ \ sim $ 0. 2 dex ). | arxiv:2103.10527 |
an empirical stochastic analysis of high - frequency, tick - by - tick order data of nasdaq100 listed stocks is conducted using a first - order discrete - time markov chain model to explore intraday order transition dynamics. this analysis focuses on three market cap categories : high, medium, and low. time - homogeneous transition probability matrices are estimated and compared across time - zones and market cap categories, and we found that limit orders exhibit higher degree of inertia ( doi ), i. e., the probability of placing consecutive limit order is higher, during the opening hour. however, in the subsequent hour, the doi of limit order decreases, while that of market order increases. limit order adjustments via additions and deletions of limit orders increases significantly after the opening hour. all the order transitions then stabilize during mid - hours. as the closing hour approaches, consecutive order executions surge, with decreased placement of buy and sell limit orders following sell and buy executions, respectively. in terms of the differences in order transitions between stocks of different market cap, doi of orders is stronger in high and medium market cap stocks. on the other hand, lower market cap stocks show a higher probability of limit order modifications and greater likelihood of submitting sell / buy limit orders after buy / sell executions. further, order transitions are clustered across all stocks, except during opening and closing hours. the findings of this study may be useful in understanding intraday order placement dynamics across stocks of varying market cap, thus aiding market participants in making informed order placements at different times of trading hour. | arxiv:2502.07625 |
understanding the spin structure of hadrons in the small $ x $ regime is an important direction to unravel the spin puzzle in hadronic physics. to include spin degrees of freedom in the small $ x $ regime requires going beyond the usual eikonal approximation in high energy qcd. we developed an effective hamiltonian approach to study spin related observables in the small $ x $ regime using the shockwave formalism. the small - $ x $ effective hamiltonian incorporates both quark and gluon propagators in the background fields and the background field induced interaction vertices up to next - to - eikonal order. a novel feature of sub - eikonal interactions is the background gluon field induced gluon radiation inside the shockwave. its relation to chromo - electrically polarized wilson line correlator is established both in small $ x $ helicity evolution and in longitudinal double - spin asymmetry for gluon production. | arxiv:2304.12842 |
the bird ' s - eye - view ( bev ) representation is a critical factor that directly impacts the 3d object detection performance, but the traditional bev grid representation induces quadratic computational cost as the spatial resolution grows. to address this limitation, we present a new camera - based 3d object detector with high - resolution vector representation : vectorformer. the presented high - resolution vector representation is combined with the lower - resolution bev representation to efficiently exploit 3d geometry from multi - camera images at a high resolution through our two novel modules : vector scattering and gathering. to this end, the learned vector representation with richer scene contexts can serve as the decoding query for final predictions. we conduct extensive experiments on the nuscenes dataset and demonstrate state - of - the - art performance in nds and inference time. furthermore, we investigate query - bev - based methods incorporated with our proposed vector representation and observe a consistent performance improvement. | arxiv:2407.15354 |
a master - worker architecture is presented for obtaining combined experimental results through joint fits of datasets from several experiments. the design of the architecture allows such joint fits to be performed keeping the data separated, in its original format, and using independent fitting environments. this allows the benefits of joint fits, such as ensuring that correlations are correctly taken into account and better determination of nuisance parameters, to be harnessed without the need to reformat data samples or to rewrite existing fitting code. the jfit framework is a c + + implementation of this idea in the laura + + package, using dedicated classes of the root package. we present the jfit framework, give instructions for its use, and demonstrate its functionalities with concrete examples. | arxiv:1409.5080 |
we present linear ensembles of dangling bond chains on a hydrogen terminated si ( 100 ) surface, patterned in the closest spaced arrangement allowed by the surface lattice. local density of states maps over a range of voltages extending spatially over the close - coupled entities reveal a rich energetic and spatial variation of electronic states. these artificial molecules exhibit collective electronic states resulting from covalent interaction of the constituent atoms. a pronounced electrostatic perturbation of dangling bond chain structure is induced by close placement of a negatively dangling bond. the electronic changes so induced are entirely removed, paradoxically, by addition of a second dangling bond. | arxiv:1607.06050 |
intelligent agents offer a new and exciting way of understanding the world of work. in this paper we apply agent - based modeling and simulation to investigate a set of problems in a retail context. specifically, we are working to understand the relationship between human resource management practices and retail productivity. despite the fact we are working within a relatively novel and complex domain, it is clear that intelligent agents could offer potential for fostering sustainable organizational capabilities in the future. the project is still at an early stage. so far we have conducted a case study in a uk department store to collect data and capture impressions about operations and actors within departments. furthermore, based on our case study we have built and tested our first version of a retail branch simulator which we will present in this paper. | arxiv:0803.1604 |
training neural networks with large batch is of fundamental significance to deep learning. large batch training remarkably reduces the amount of training time but has difficulties in maintaining accuracy. recent works have put forward optimization methods such as lars and lamb to tackle this issue through adaptive layer - wise optimization using trust ratios. though prevailing, such methods are observed to still suffer from unstable and extreme trust ratios which degrades performance. in this paper, we propose a new variant of lamb, called lambc, which employs trust ratio clipping to stabilize its magnitude and prevent extreme values. we conducted experiments on image classification tasks such as imagenet and cifar - 10 and our empirical results demonstrate promising improvements across different batch sizes. | arxiv:2011.13584 |
in this paper, we propose a distributed intelligent video surveillance ( divs ) system using deep learning ( dl ) algorithms and deploy it in an edge computing environment. we establish a multi - layer edge computing architecture and a distributed dl training model for the divs system. the divs system can migrate computing workloads from the network center to network edges to reduce huge network communication overhead and provide low - latency and accurate video analysis solutions. we implement the proposed divs system and address the problems of parallel training, model synchronization, and workload balancing. task - level parallel and model - level parallel training methods are proposed to further accelerate the video analysis process. in addition, we propose a model parameter updating method to achieve model synchronization of the global dl model in a distributed ec environment. moreover, a dynamic data migration approach is proposed to address the imbalance of workload and computational power of edge nodes. experimental results showed that the ec architecture can provide elastic and scalable computing power, and the proposed divs system can efficiently handle video surveillance and analysis tasks. | arxiv:1904.06400 |
using the holographic correspondence as a tool, we determine the steady - state velocity of expanding vacuum bubbles nucleated within chiral finite temperature first - order phase transitions occurring in strongly - coupled large $ n $ qcd - like models. we provide general formulae for the friction force exerted by the plasma on the bubbles and for the steady - state velocity. in the top - down holographic description, the phase transitions are related to changes in the embedding of $ dq $ - $ { \ bar dq } $ flavor branes probing the black hole background sourced by a stack of $ n $ $ dp $ - branes. we first consider the witten - sakai - sugimoto $ d4 $ - $ d8 $ - $ \ bar d8 $ setup, compute the friction force and deduce the equilibrium velocity. then we extend our analysis to more general setups and to different dimensions. finally, we briefly compare our results, obtained within a fully non - perturbative framework, to other estimates of the bubble velocity in the literature. | arxiv:2104.12817 |
in contrast to massless spinning particles, scalars are not heavily constrained by unitarity and locality. off - shell, no gauge symmetries are required to write down manifestly local theories, while on - shell consistent factorisation is trivial. instead a useful classification scheme for scalars is based on the symmetries they can non - linearly realise. motivated by the breaking of lorentz boosts in cosmology, in this paper we classify the possible symmetries of a shift - symmetric scalar that is assumed to non - linearly realise lorentz boosts as, for example, in the eft of inflation. our classification method is algebraic ; guided by the coset construction and inverse higgs constraints. we rediscover some known phonon theories within the superfluid and galileid classes, and discover a new galileid theory which we call the $ \ textit { extended galileid } $. generic galileids correspond to the broken phase of galileon scalar efts and our extended galileids correspond to special subsets where each galileon coupling is fixed by an additional symmetry. we discuss the broken phase of theories that also admit a perturbation theory around poincar \ ' { e } invariant vacua and we show that the so - called exceptional efts, the dbi scalar and special galileon, do not admit such a broken phase. concentrating on dbi we provide a detailed account of this showing that the scattering amplitudes are secretly poincar \ ' { e } invariant when the theory is expanded around the superfluid background used in the eft of inflation. we point out that dbi is an exception to the common lore that the residue of the total energy pole of cosmological correlators is proportional to the amplitude. we also discuss the inevitability of poles in $ 2 \ rightarrow 2 $ scattering amplitudes when boost are spontaneously broken meaning that such theories do not admit adler zeros and generalisations even in the presence of a shift symmetry. | arxiv:2005.12937 |
the herschel lensing survey ( hls ) will conduct deep pacs and spire imaging of ~ 40 massive clusters of galaxies. the strong gravitational lensing power of these clusters will enable us to penetrate through the confusion noise, which sets the ultimate limit on our ability to probe the universe with herschel. here, we present an overview of our survey and a summary of the major results from our science demonstration phase ( sdp ) observations of the bullet cluster ( z = 0. 297 ). the sdp data are rich, allowing us to study not only the background high - redshift galaxies ( e. g., strongly lensed and distorted galaxies at z = 2. 8 and 3. 2 ) but also the properties of cluster - member galaxies. our preliminary analysis shows a great diversity of far - infrared / submillimeter spectral energy distributions ( seds ), indicating that we have much to learn with herschel about the properties of galaxy seds. we have also detected the sunyaev - zel ' dovich ( sz ) effect increment with the spire data. the success of this sdp program demonstrates the great potential of the herschel lensing survey to produce exciting results in a variety of science areas. | arxiv:1005.3820 |
by means of interferometic 21 - cm observations and a 3d kinematic modeling technique, we study the gas kinematics of six hi - rich ultra - diffuse galaxies ( udgs ). we derive robust circular velocities and baryonic masses, that allow us to study the position of our udgs with respect to the baryonic tully - fisher relation ( btfr ). somewhat surprisingly, we find that these galaxies are strong outliers from the btfr, rotating too slowly for their baryonic mass. moreover, their position in the circular velocity - - baryonic mass plane implies that they have a baryon fraction inside their virial radii compatible with the cosmological mean, meaning that they have no " missing baryons ". unexpectedly, the dynamics of our galaxies are dominated by the baryons, leaving small room for dark matter inside their discs. | arxiv:1910.07463 |
the coherent potential approximation has historically allowed the efficient study of disorder effects over a variety of solid state systems. its original formulation is however limited to a single - site or uncorrelated model of local substitutions. this neglects the effects of correlation and short range ordering, often found in realistic materials. recent theoretical work has shown how to systematically address such shortcomings, for simple materials with only one element per unit cell. we briefly review the basic ideas of these developments within the framework of multiple scattering theory, and suggest their generalization to materials with complex lattices and possibly different types of disorder. we illustrate this extension with an example of local environment effects in the exotic hapkeite $ fe - fe _ { 37. 5 % } si _ { 62. 5 % } $ compound. | arxiv:1206.5981 |
we report the results of the first computation related to the study of the spectator effects in the rare decay mode $ b \ to k \ gamma \ gamma $ within the framework of standard model. it is found that the account of these effects results in the enhancement factor for the short - distance reducible contribution to the branching ratio. | arxiv:hep-ph/0308126 |
we consider solving the laplace - beltrami problem on a smooth two dimensional surface embedded into a three dimensional space meshed with tetrahedra. the mesh does not respect the surface and thus the surface cuts through the elements. we consider a galerkin method based on using the restrictions of continuous piecewise linears defined on the tetrahedra to the surface as trial and test functions. the resulting discrete method may be severely ill - conditioned, and the main purpose of this paper is to suggest a remedy for this problem based on adding a consistent stabilization term to the original bilinear form. we show optimal estimates for the condition number of the stabilized method independent of the location of the surface. we also prove optimal a priori error estimates for the stabilized method. | arxiv:1312.1097 |
the essay argues that the standard cosmological model is one sided and incomplete. its recognition of the primacy of radiant energy has no rational justification and empirical verification and, therefore, is arbitrary and subjective. the subjective and arbitrary choice of this foundational self evident truth renders the entire standard model subjective and arbitrary. numerous paradoxes and inconsistencies plague the standard model. as a result, from the perspective of the standard cosmological model the universe appears, as some cosmologists argue, absurd and many of its parts seem inaccessible to our understanding. the essay attempts to provide a more balanced approach. it argues that the recognition of equal importance of both radiant and nonradiant forms of energy and matter is essential for a comprehensive and objective understanding of how the universe works. the essay also tries to outline the new cosmological model that recognizes the equal importance of both types of energy and matter and of their complementary relationship. | arxiv:2012.12749 |
cyclic codes are an important class of linear codes. bounding the minimum distance of cyclic codes is a long - standing research topic in coding theory, and several well - known and basic results have been developed on this topic. recently, locally repairable codes ( lrcs ) have attracted much attention due to their repair efficiency in large - scale distributed storage systems. in this paper, by employing the singleton procedure technique, we first provide a sufficient condition for bounding the minimum distance of cyclic codes with typical defining sets. secondly, by considering a specific case, we establish a connection between bounds for the minimum distance of cyclic codes and solutions to a system of inequalities. this connection leads to the derivation of new bounds, including some with general patterns. in particular, we provide three new bounds with general patterns, one of which serves as a generalization of the betti - sala bound. finally, we present a generalized lower bound for a special case and construct several families of $ ( 2, \ delta ) $ - lrcs with unbounded length and minimum distance $ 2 \ delta $. it turns out that these lrcs are distance - optimal, and their parameters are new. to the best of our knowledge, this work represents the first construction of distance - optimal $ ( r, \ delta ) $ - lrcs with unbounded length and minimum distance exceeding $ r + \ delta - 1 $. | arxiv:2310.07524 |
2 − 1 ) k ( 1 q 2 ) ) − ( q 2 − 1 ) ( q e ( 1 q 2 ) − q 2 − 1 q k ( 1 q 2 ) ) } = 4 9 π { q ( q 2 + 7 ) e ( 1 q 2 ) − q 2 − 1 q ( q 2 + 3 ) k ( 1 q 2 ) } { \ displaystyle { \ begin { aligned } b ( q ) & = { \ frac { 4 } { 3 \ pi } } \ int _ { 0 } ^ { 1 } { \ biggl \ { } 3 { \ sqrt { q ^ { 2 } - u ^ { 2 } } } { \ sqrt { 1 - u ^ { 2 } } } + { \ frac { ( 1 - u ^ { 2 } ) ^ { \ tfrac { 3 } { 2 } } } { \ sqrt { q ^ { 2 } - u ^ { 2 } } } } { \ biggr \ } } { \ textrm { d } } u \ \ [ 0. 6ex ] & = { \ frac { 4 } { 3 \ pi } } \ int _ { 0 } ^ { 1 } { \ biggl \ { } 4 { \ sqrt { q ^ { 2 } - u ^ { 2 } } } { \ sqrt { 1 - u ^ { 2 } } } - { \ frac { q ^ { 2 } - 1 } { q } } { \ frac { \ sqrt { 1 - u ^ { 2 } } } { \ sqrt { q ^ { 2 } - u ^ { 2 } } } } { \ biggr \ } } { \ textrm { d } } u \ \ [ 0. 6ex ] & = { \ frac { 4 } { 3 \ pi } } { \ biggl \ { } { \ frac { 4q } { 3 } } { \ biggl ( } ( q ^ { 2 } + 1 ) e ( { \ tfrac { 1 } { q ^ { 2 } } } ) - ( q ^ { 2 } - 1 ) k ( { \ tfrac { 1 } { q ^ { 2 } } } ) { \ biggr ) } - ( q ^ { 2 } - 1 ) { \ biggl ( } qe ( { \ tfrac { 1 } { q ^ { 2 } } } ) - | https://en.wikipedia.org/wiki/Disk_(mathematics) |
we show a distortion lower bound of $ \ omega ( \ log ( h ) ^ { 1 / p } ) $ when embedding the countably branching hyperbolic tree of height $ h $ into a banach space with an equivalent norm satisfying rolewicz property $ ( \ beta ) $ with modulus of power type $ p > 1 $. similarly we show that a distortion lower bound of $ \ omega ( l ^ { 1 / p } ) $ is incurred when embedding the parasol graphs with $ l $ levels into a banach space with the above property. we discuss the optimality of our results as well as several applications. | arxiv:1411.3915 |
although the topic of opinion polarization receives much attention from the media, public opinion researchers and political scientists, the phenomenon itself has not been adequately characterized in either the lay or academic literature. to study opinion polarization among the public, researchers compare the distributions of respondents to survey questions or track the distribution of responses to a question over time using ad - hoc methods and measures such as visual comparisons, variances, and bimodality coefficients. to remedy this situation, we build on the axiomatic approach in the economics literature on income bipolarization, specifying key properties a measure of bipolarization should satisfy : in particular, it should increase as the distribution spreads away from a center toward the poles and / or as clustering below or above this center increases. we then show that measures of bipolarization used in public opinion research fail to satisfy one or more of these axioms. next, we propose a $ p $ - wasserstein polarization index that satisfies the axioms we set forth. our index measures the dissimilarity between an observed distribution and a distribution with all the mass clustered on the lower and upper endpoints of the scale. we use our index to examine bipolarization in attitudes toward governmental covid - 19 vaccine mandates across 11 countries, finding the u. s and u. k are most polarized, china, france and india the least polarized, while the others ( brazil, australia, colombia, canada, italy, spain ) occupy an intermediate position. | arxiv:2408.03331 |
early detection of psychological distress is key to effective treatment. automatic detection of distress, such as depression, is an active area of research. current approaches utilise vocal, facial, and bodily modalities. of these, the bodily modality is the least investigated, partially due to the difficulty in extracting bodily representations from videos, and partially due to the lack of viable datasets. existing body modality approaches use automatic categorization of expressions to represent body language as a series of specific expressions, much like words within natural language. in this dissertation i present a new type of feature, within the body modality, that represents meta information of gestures, such as speed, and use it to predict a non - clinical depression label. this differs to existing work by representing overall behaviour as a small set of aggregated meta features derived from a person ' s movement. in my method i extract pose estimation from videos, detect gestures within body parts, extract meta information from individual gestures, and finally aggregate these features to generate a small feature vector for use in prediction tasks. i introduce a new dataset of 65 video recordings of interviews with self - evaluated distress, personality, and demographic labels. this dataset enables the development of features utilising the whole body in distress detection tasks. i evaluate my newly introduced meta - features for predicting depression, anxiety, perceived stress, somatic stress, five standard personality measures, and gender. a linear regression based classifier using these features achieves a 82. 70 % f1 score for predicting depression within my novel dataset. | arxiv:2003.00809 |
the evolution of a generally covariant theory is under - determined. one hundred years ago such dynamics had never before been considered ; its ramifications were perplexing, its future important role for all the fundamental interactions under the name gauge principle could not be foreseen. we recount some history regarding einstein, hilbert, klein and noether and the novel features of gravitational energy that led to noether ' s two theorems. under - determined evolution is best revealed in the hamiltonian formulation. we developed a covariant hamiltonian formulation. the hamiltonian boundary term gives covariant expressions for the quasi - local energy, momentum and angular momentum. gravity can be considered as a gauge theory of the local poincar \ ' e group. the dynamical potentials of the poincar \ ' e gauge theory of gravity are the frame and the connection. the spacetime geometry has in general both curvature and torsion. torsion naturally couples to spin ; it could have a significant magnitude and yet not be noticed, except on a cosmological scale where it could have significant effects. | arxiv:1604.05547 |
most audio processing pipelines involve transformations that act on fixed - dimensional input representations of audio. for example, when using the short time fourier transform ( stft ) the dft size specifies a fixed dimension for the input representation. as a consequence, most audio machine learning models are designed to process fixed - size vector inputs which often prohibits the repurposing of learned models on audio with different sampling rates or alternative representations. we note, however, that the intrinsic spectral information in the audio signal is invariant to the choice of the input representation or the sampling rate. motivated by this, we introduce a novel way of processing audio signals by treating them as a collection of points in feature space, and we use point cloud machine learning models that give us invariance to the choice of representation parameters, such as dft size or the sampling rate. additionally, we observe that these methods result in smaller models, and allow us to significantly subsample the input representation with minimal effects to a trained model performance. | arxiv:2105.02469 |
the oscillator bases expansion stands as an efficient approximation method for the time - independent schr \ " odinger equation. the method, originally formulated with one non - linear variational parameter, can be extended to incorporate two such parameters. it handles both non - and semi - relativistic kinematics with generic two - body interactions. in the current work, focusing on systems of three identical bodies, the method is generalised to include the management of a given class of three - body forces. the computational cost of this generalisation proves to not exceed the one for two - body interactions. the accuracy of the generalisation is assessed by comparing with results from lagrange mesh method and hyperspherical harmonic expansions. extensions for systems of $ n $ identical bodies and for systems of two identical particles and one distinct are also discussed. | arxiv:2405.18184 |
these lecture notes provide a self - contained introduction to euler integrals, which are frequently encountered in applications. in particle physics, they arise as feynman integrals or string amplitudes. our four selected topics demonstrate the diverse mathematical techniques involved in the study of euler integrals, including polyhedral geometry, very affine varieties, differential equations, and computational algebra. | arxiv:2306.13578 |
we have studied the frequency and voltage dependence of voltage - induced torsional strains in orthorhombic tas3 [ v. ya. pokrovskii, et al, phys. rev. lett. 98, 206404 ( 2007 ) ] by measuring the modulation of the resonant frequency of an rf cavity containing the sample. the strain has an onset voltage below the charge - density - wave ( cdw ) threshold voltages associated with changes in shear compliance and resistance, suggesting that the strain is associated with polarization of the cdw rather than cdw current. measurements with square - wave voltages show that the strain is very sluggish, not even reaching its dc value at a frequency of 0. 1 hz, but the dynamics appear to be very sample dependent. by applying oscillating torque while biasing the sample with a dc current, we have also looked for strain induced voltage in the sample ; none is observed at the low biases where the voltage - induced strains first occur, but an induced voltage is observed at higher biases, probably associated with strain - dependent cdw conductance. | arxiv:0905.2426 |
the cms silicon tracking system measures the trajectories of charged particles with a hit resolution of the order of microns in the pixel detector and tens of microns in the strip detector. one of the most important inputs for track reconstruction is the precision with which the tracker geometry is known. therefore the position, orientation, and curvature of each tracker sensor must be precisely determined. changes in the operating conditions can cause movements in the different substructures and also in the sensors. for maintaining the targeted precision, frequent corrections are needed, and the procedure to determine these corrections is commonly referred to as tracker alignment. due to accumulated radiation during data taking, the response of the sensors changes over time. this affects the local reconstruction of pixel hits and consequently the result of the alignment procedure. in this contribution, the alignment procedure in cms is introduced, as well as the dedicated calibration for the pixel local reconstruction. the effect of the change in the local reconstruction due to aging of the sensors on the alignment procedure is discussed. | arxiv:2303.16642 |
involvement hot spots have been proposed as a useful concept for meeting analysis and studied off and on for over 15 years. these are regions of meetings that are marked by high participant involvement, as judged by human annotators. however, prior work was either not conducted in a formal machine learning setting, or focused on only a subset of possible meeting features or downstream applications ( such as summarization ). in this paper we investigate to what extent various acoustic, linguistic and pragmatic aspects of the meetings, both in isolation and jointly, can help detect hot spots. in this context, the opensmile toolkit is to used to extract features based on acoustic - prosodic cues, bert word embeddings are used for encoding the lexical content, and a variety of statistics based on speech activity are used to describe the verbal interaction among participants. in experiments on the annotated icsi meeting corpus, we find that the lexical model is the most informative, with incremental contributions from interaction and acoustic - prosodic model components. | arxiv:1910.10869 |
almost 30 years ago, zhang and shasha ( 1989 ) published a seminal paper describing an efficient dynamic programming algorithm computing the tree edit distance, that is, the minimum number of node deletions, insertions, and replacements that are necessary to transform one tree into another. since then, the tree edit distance has been widely applied, for example in biology and intelligent tutoring systems. however, the original paper of zhang and shasha can be challenging to read for newcomers and it does not describe how to efficiently infer the optimal edit script. in this contribution, we provide a comprehensive tutorial to the tree edit distance algorithm of zhang and shasha. we further prove metric properties of the tree edit distance, and describe efficient algorithms to infer the cheapest edit script, as well as a summary of all cheapest edit scripts between two trees. | arxiv:1805.06869 |
we study experimentally and theoretically the polarization alternation during the switch - on transient of a quasi - isotropic co $ _ 2 $ laser emitting on the fundamental mode. the observed transient dynamics is well reproduced by means of a model which provides a quantitative discrimination between the intrinsic asymmetry due to the kinetic coupling of molecules with different angular momenta, and the extrinsic anisotropies, due to a tilted intracavity window. furthermore, the experiment provides a numerical assignment for the decay rate of the coherence term for a co $ _ 2 $ laser. | arxiv:physics/0210086 |
wu and jans introduced quasi - projective modules where they say a $ \ cal r $ module $ \ cal m $ is quasi - projective if for every submodule $ \ cal n $, for every homomorphism $ f : { \ cal m } \ rightarrow { \ cal m } / { \ cal n } $ and every epimorphism $ j : { \ cal m } \ rightarrow { \ cal m } / { \ cal n } $ there is an endomorphism $ \ phi $ of $ \ cal m $ such that $ \ phi \ circ j = f $. we say that a structure $ \ cal s $ is quasi - projective if for every structure $ \ cal t $, for every homomorphism $ f : { \ cal s } \ rightarrow { \ cal t } $ and every epimorphism $ j : { \ cal s } \ rightarrow { \ cal t } $ there is an endomorphism $ \ phi $ of $ \ cal s $ such that $ \ phi \ circ j = f $. in 2004 d. jakub \ ' ikov \ ' a - studenovsk \ ' a defined the concept of the factor algebra denoted by $ { \ cal a } / { \ cal b } $, where $ { \ cal a } $ is a monounary algebra and $ { \ cal b } $ is a subalgebra of $ \ cal a $. in this paper, we characterise the quasi - projective monounary algebras of arbitrary cardinalities for the definition of d. jakub \ ' ikov \ ' a - studenovsk \ ' a and for the second definition. | arxiv:2011.11799 |
kardashev type iii civilisations have by definition energy requirements that are likely to generate strong excess emission in the mid - infrared ( mir ) that is associated with the waste heat they generate. for those civilisations that capture starlight via dyson sphere like constructions, the optical to mir flux ratio of the host galaxies is also expected to be unusually low. since a wide range of galaxy types adhere to the infrared - radio correlation ( irc ), galaxies hosting type iii civilisations should also strongly deviate from this relation. radio data can therefore play a crucial role in breaking the degeneracy between the effects of dust obscuration in a galaxy and the signature of an energy - intensive civilisation. we have used the newly released lotss - dr1 value - added catalogue to create a sample of 16, 367 $ z < 0. 2 $ sources with radio and mir flux densities, optical photometry and ( photometric ) redshifts. we calculated the irc parameter $ q ^ { { \ rm22 ~ \ mu m } } _ { { \ rm 150 ~ mhz } } $ = log ( $ s _ { 150 ~ { \ rm mhz } } $ / $ s _ { 22 ~ { \ rm \ mu m } } $ ) and identified 21 sources with exceptionally high values of $ q ^ { { \ rm22 ~ \ mu m } } _ { { \ rm 150 ~ mhz } } $, an indication of mir emission enhanced by a factor of $ \ sim $ 10. out of the 21 high $ q $ - value sources, 4 sources have very red mir colors, and appear to have relatively low optical / mir ratios. two of the 4 sources are not well known in the literature, they are considered as potential hosts of type iii civilisations. these sources deserve further study and investigation. finally, we note that extending our analysis to the full lotss survey area can place very strong constraints on the incidence of type iii civilisations in the universe. | arxiv:2108.06597 |
for random - walk metropolis ( rwm ) and parallel tempering ( pt ) algorithms, an asymptotic acceptance rate of around 0. 234 is known to be optimal in the high - dimensional limit. however, its practical relevance is uncertain due to restrictive derivation conditions. we synthesise previous theoretical advances in extending the 0. 234 acceptance rate to more general settings, and demonstrate its applicability with a comprehensive empirical simulation study on examples examining how acceptance rates affect expected squared jumping distance ( esjd ). our experiments show the optimality of the 0. 234 acceptance rate for rwm is surprisingly robust even in lower dimensions across various proposal and multimodal target distributions which may or may not have an i. i. d. product density. parallel tempering experiments also show that the idealized 0. 234 spacing of inverse temperatures may be approximately optimal for low dimensions and non i. i. d. product target densities, and that constructing an inverse temperature ladder with spacings given by a swap acceptance of 0. 234 is a viable strategy. however, we observe the applicability of the 0. 234 acceptance rate heuristic diminishes for both rwm and pt algorithms below a certain dimension which differs based on the target density, and that inhomogeneously scaled components in the target density further reduces its applicability in lower dimensions. | arxiv:2408.06894 |
we employ the complex langevin method for simulation of complex - valued actions. first, we show how to test for convergence of the method by explicitely computing boundary terms and demonstrate this in a model. then we investigate the deconfinement phase transition of qcd with $ n _ f = 2 $ wilson - fermions using the complex langevin method and. we give preliminary results for the transition temperatures up to $ \ mu / t _ c ( \ mu = 0 ) \ approx 5 $ and compute the curvature coefficient $ \ kappa _ 2 $. | arxiv:1810.09713 |
most named entity recognition ( ner ) systems use additional features like part - of - speech ( pos ) tags, shallow parsing, gazetteers, etc. such kind of information requires external knowledge like unlabeled texts and trained taggers. adding these features to ner systems have been shown to have a positive impact. however, sometimes creating gazetteers or taggers can take a lot of time and may require extensive data cleaning. in this paper for chinese ner systems, we do not use these traditional features but we use lexicographic features of chinese characters. chinese characters are composed of graphical components called radicals and these components often have some semantic indicators. we propose cnn based models that incorporate this semantic information and use them for ner. our models show an improvement over the baseline bert - bilstm - crf model. we set a new baseline score for chinese ontonotes v5. 0 and show an improvement of +. 64 f1 score. we present a state - of - the - art f1 score on weibo dataset of 71. 81 and show a competitive improvement of + 0. 72 over baseline on resumener dataset. | arxiv:1909.09922 |
optically active artificial structures have attracted tremendous research attention. such structures must meet two requirements : lack of spatial inversion symmetries and, a condition usually not explicitly considered, the structure shall preserve the helicity of light, which implies that there must be a vanishing coupling between the states of opposite polarization handedness among incident and scattered plane waves. here, we put forward and demonstrate that a unit cell made from chiraly arranged electromagnetically dual scatterers serves exactly this purpose. we prove this by demonstrating optical activity of such unit cell in general scattering directions. | arxiv:1606.08754 |
this paper study the two - - phase problem for the forward - backward parabolic equation with diffusion function of cubic type. existence and uniqueness for these kind of problems were obtained in literature in the case in which the phases are both stable. here we consider the situation in which the unstable phase is taken in account, obtaining not trivial solution of the problem. it is interesting to note that such solutions are given by solving generalized abel ' s equations. | arxiv:1310.7728 |
rapid design and development of the emergent ultra - wide bandgap semiconductors ga $ _ 2 $ o $ _ 3 $ and al $ _ 2 $ o $ _ 3 $ requires a compact model of their electronic structures, accurate over the broad energy range accessed in future high - field, high - frequency, and high - temperature electronics and visible and ultraviolet photonics. a minimal tight - binding model is developed to reproduce the first - principles electronic structures of the $ \ beta - $ and $ \ alpha - $ phases of ga $ _ 2 $ o $ _ 3 $ and al $ _ 2 $ o $ _ 3 $ throughout their reciprocal spaces. accurately reproducing the bandgap, orbital character, and effective mass and high - energy features of the conduction band, this compact model will assist in the investigation and design of the electrical and optical properties of bulk materials, devices, and quantum confined heterostructures. | arxiv:2111.03959 |
the berezinskii - - kosterlitz - - thouless ( bkt ) transition of the two - dimensional $ xy $ model on the honeycomb lattice is investigated using both the techniques of neural network ( nn ) and monte carlo simulations. it is demonstrated in the literature that with certain plausible assumptions, the associated critical temperature $ t _ { \ text { bkt, h } } $ is found to be $ \ frac { 1 } { \ sqrt { 2 } } $ exactly. surprisingly, the value of $ t _ { \ text { bkt, h } } $ obtained from our nn calculations is 0. 560 ( 9 ) which deviates significantly from $ \ frac { 1 } { \ sqrt { 2 } } $. in addition, based on the helicity modulus, the $ t _ { \ text { bkt, h } } $ determined is 0. 571 ( 8 ) agreeing well with that resulting from the nn estimation. the outcomes presented in this study indicate that a detailed analytic calculation is desirable to solve the found discrepancy. | arxiv:2406.14812 |
8 ( x ^ { 2 } + y ^ { 2 } ) - 2x - 36y + 35 = 0 } ( x − 1 8 ) 2 + ( y − 9 4 ) 2 = 45 64. { \ displaystyle \ leftrightarrow \ left ( x - { \ frac { 1 } { 8 } } \ right ) ^ { 2 } + \ left ( y - { \ frac { 9 } { 4 } } \ right ) ^ { 2 } = { \ frac { 45 } { 64 } }. } this equation represents a circle with center ( 1 / 8, 9 / 4 ) and radius 3 8 5 { \ displaystyle { \ tfrac { 3 } { 8 } } { \ sqrt { 5 } } }. it is the circle of apollonius defined by these values of k, a, and b. = = = second example = = = a triangle abc has a fixed side [ ab ] with length c. determine the locus of the third vertex c such that the medians from a and c are orthogonal. choose an orthonormal coordinate system such that a ( −c / 2, 0 ), b ( c / 2, 0 ). c ( x, y ) is the variable third vertex. the center of [ bc ] is m ( ( 2x + c ) / 4, y / 2 ). the median from c has a slope y / x. the median am has slope 2y / ( 2x + 3c ). c ( x, y ) is a point of the locus { \ displaystyle \ leftrightarrow } the medians from a and c are orthogonal y x ⋅ 2 y 2 x + 3 c = − 1 { \ displaystyle \ leftrightarrow { \ frac { y } { x } } \ cdot { \ frac { 2y } { 2x + 3c } } = - 1 } 2 y 2 + 2 x 2 + 3 c x = 0 { \ displaystyle \ leftrightarrow 2y ^ { 2 } + 2x ^ { 2 } + 3cx = 0 } x 2 + y 2 + ( 3 c / 2 ) x = 0 { \ displaystyle \ leftrightarrow x ^ { 2 } + y ^ { 2 } + ( 3c / 2 ) x = 0 } ( x + 3 c / 4 ) 2 + y 2 = 9 c 2 / | https://en.wikipedia.org/wiki/Locus_(mathematics) |
we study the dispersive properties of a linear equation in one spatial dimension which is inspired by models in peridynamics. the interplay between nonlocality and dispersion is analyzed in detail through the study of the asymptotics at low and high frequencies, revealing new features ruling the wave propagation in continua where nonlocal characteristics must be taken into account. global dispersive estimates and existence of conserved functionals are proved. a comparison between these new effects and the classical local { \ it scenario } is deepened also through a numerical analysis. | arxiv:2105.01558 |
learning from demonstration ( lfd ) is a promising approach to enable multi - robot systems ( mrs ) to acquire complex skills and behaviors. however, the intricate interactions and coordination challenges in mrs pose significant hurdles for effective lfd. in this paper, we present a novel lfd framework specifically designed for mrs, which leverages visual demonstrations to capture and learn from robot - robot and robot - object interactions. our framework introduces the concept of interaction keypoints ( iks ) to transform the visual demonstrations into a representation that facilitates the inference of various skills necessary for the task. the robots then execute the task using sensorimotor actions and reinforcement learning ( rl ) policies when required. a key feature of our approach is the ability to handle unseen contact - based skills that emerge during the demonstration. in such cases, rl is employed to learn the skill using a classifier - based reward function, eliminating the need for manual reward engineering and ensuring adaptability to environmental changes. we evaluate our framework across a range of mobile robot tasks, covering both behavior - based and contact - based domains. the results demonstrate the effectiveness of our approach in enabling robots to learn complex multi - robot tasks and behaviors from visual demonstrations. | arxiv:2404.02324 |
common intervals have been defined as a modelisation of gene clusters in genomes represented either as permutations or as sequences. whereas optimal algorithms for finding common intervals in permutations exist even for an arbitrary number of permutations, in sequences no optimal algorithm has been proposed yet even for only two sequences. surprisingly enough, when sequences are reduced to permutations, the existing algorithms perform far from the optimum, showing that their performances are not dependent, as they should be, on the structural complexity of the input sequences. in this paper, we propose to characterize the structure of a sequence by the number $ q $ of different dominating orders composing it ( called the domination number ), and to use a recent algorithm for permutations in order to devise a new algorithm for two sequences. its running time is in $ o ( q _ 1q _ 2p + q _ 1n _ 1 + q _ 2n _ 2 + n ) $, where $ n _ 1, n _ 2 $ are the sizes of the two sequences, $ q _ 1, q _ 2 $ are their respective domination numbers, $ p $ is the alphabet size and $ n $ is the number of solutions to output. this algorithm performs better as $ q _ 1 $ and / or $ q _ 2 $ reduce, and when the two sequences are reduced to permutations ( i. e. when $ q _ 1 = q _ 2 = 1 $ ) it has the same running time as the best algorithms for permutations. it is also the first algorithm for sequences whose running time involves the parameter size of the solution. as a counterpart, when $ q _ 1 $ and $ q _ 2 $ are of $ o ( n _ 1 ) $ and $ o ( n _ 2 ) $ respectively, the algorithm is less efficient than other approaches. | arxiv:1310.4290 |
context. diffusive shock acceleration ( dsa ) is the most promising mechanism to accelerate galactic cosmic rays ( crs ) in the shocks of supernova remnants ( snrs ). the turbulence upstream is supposedly generated by the crs, but this process is not well understood. the dominant mechanism may depend on the evolutionary state of the shock and can be studied via the crs escaping upstream into the interstellar medium ( ism ). aims. previous observations of the $ \ gamma $ - cygni snr showed a difference in morphology between gev and tev energies. since this snr has the right age and is at the evolutionary stage for a significant fraction of crs to escape, we aim to understand $ \ gamma $ - ray emission in the vicinity of the $ \ gamma $ - cygni snr. methods. we observed the region of the $ \ gamma $ - cygni snr with the magic imaging atmospheric cherenkov telescopes between may 2015 and september 2017 recording 87 h of good - quality data. additionally we analysed fermi - lat data to study the energy dependence of the morphology as well as the energy spectrum in the gev to tev range. the energy spectra and morphology were compared against theoretical predictions, which include a detailed derivation of the cr escape process and their $ \ gamma $ - ray generation. results. the magic and fermi - lat data allowed us to identify three emission regions, which can be associated with the snr and dominate at different energies. our hadronic emission model accounts well for the morphology and energy spectrum of all source components. it constrains the time - dependence of the maximum energy of the crs at the shock, the time - dependence of the level of turbulence, and the diffusion coefficient immediately outside the snr shock. while in agreement with the standard picture of dsa, the time - dependence of the maximum energy was found to be steeper than predicted and the level of turbulence was found to change over the lifetime of the snr. | arxiv:2010.15854 |
this paper describes an application, called medici, designed to produce synthetic data for social network graphs, which can be used for analysis, hypothesis testing and application development by researchers and practitioners in the field. it builds on previous work by providing an integrated system, and a user friendly screen interface. it can be run with default values to produce graph data and statistics, which can then be used for further processing. the system is made publicly available in a github java project. the annex provides a user manual with a screen by screen guide. | arxiv:2101.01956 |
research into the external behaviors and internal mechanisms of large language models ( llms ) has shown promise in addressing complex tasks in the physical world. studies suggest that powerful llms, like gpt - 4, are beginning to exhibit human - like cognitive abilities, including planning, reasoning, and reflection. in this paper, we introduce a research line and methodology called llm psychology, leveraging human psychology experiments to investigate the cognitive behaviors and mechanisms of llms. we migrate the typoglycemia phenomenon from psychology to explore the " mind " of llms. unlike human brains, which rely on context and word patterns to comprehend scrambled text, llms use distinct encoding and decoding processes. through typoglycemia experiments at the character, word, and sentence levels, we observe : ( i ) llms demonstrate human - like behaviors on a macro scale, such as lower task accuracy and higher token / time consumption ; ( ii ) llms exhibit varying robustness to scrambled input, making typoglycemia a benchmark for model evaluation without new datasets ; ( iii ) different task types have varying impacts, with complex logical tasks ( e. g., math ) being more challenging in scrambled form ; ( iv ) each llm has a unique and consistent " cognitive pattern " across tasks, revealing general mechanisms in its psychology process. we provide an in - depth analysis of hidden layers to explain these phenomena, paving the way for future research in llm psychology and deeper interpretability. | arxiv:2410.01677 |
we show for the first time that collectively jammed disordered packings of three - dimensional monodisperse frictionless hard spheres can be produced and tuned using a novel numerical protocol with packing density $ \ phi $ as low as 0. 6. this is well below the value of 0. 64 associated with the maximally random jammed state and entirely unrelated to the ill - defined ` ` random loose packing ' ' state density. specifically, collectively jammed packings are generated with a very narrow distribution centered at any density $ \ phi $ over a wide density range $ \ phi \ in [ 0. 6, ~ 0. 74048 \ ldots ] $ with variable disorder. our results support the view that there is no universal jamming point that is distinguishable based on the packing density and frequency of occurence. our jammed packings are mapped onto a density - order - metric plane, which provides a broader characterization of packings than density alone. other packing characteristics, such as the pair correlation function, average contact number and fraction of rattlers are quantified and discussed. | arxiv:1101.1327 |
we have developed a torsion pendulum facility for lisa gravitational reference sensor ground testing that allows us to put significant upper limits on residual stray forces exerted by lisa - like position sensors on a representative test mass and to characterize specific sources of disturbances for lisa. we present here the details of the facility, the experimental procedures used to maximize its sensitivity, and the techniques used to characterize the pendulum itself that allowed us to reach a torque sensitivity below 20 fnm / sqrt { hz } from 0. 3 to 10 mhz. we also discuss the implications of the obtained results for lisa. | arxiv:gr-qc/0310119 |
we use the s - matrix bootstrap to carve out the space of unitary, analytic, crossing symmetric and supersymmetric graviton scattering amplitudes in nine, ten and eleven dimensions. we extend and improve the numerical methods of our previous work in ten dimensions. a key new tool employed here is unitarity in the celestial sphere. in all dimensions, we find that the minimal allowed value of the wilson coefficient $ \ alpha $, controlling the leading correction to maximal supergravity, is very close but not equal to the minimal value realized in superstring theory or m - theory. this small difference may be related to inelastic effects that are not well described by our numerical extremal amplitudes. although $ \ alpha $ has a unique value in m - theory, we found no evidence of an upper bound on $ \ alpha $ in 11d. | arxiv:2212.00151 |
in a space based gravitational wave antenna like lisa, involving long light paths linking distant emitter / receiver spacecrafts, signal detection amounts to measuring the light - distance variationsthrough a phase change at the receiver. this is why spurious phase fluctuations due to various mechanical / thermal effects must be carefully studied. we consider here a possible pointing jitter in the light beam sent from the emitter. we show how the resulting phase noise depends on the quality of the wavefront due to the incident beam impinging on the telescope and due to the imperfections of the telescope itself. namely, we numerically assess the crossed influence of various defects ( aberrations and astigmatisms ), inherent to a real telescope with pointing fluctuations. | arxiv:1909.08566 |
we use a sample of 17 strong gravitational lens systems from the bells gallery survey to quantify the amount of low - mass dark matter haloes within the lensing galaxies and along their lines of sight, and to constrain the properties of dark matter. based on a detection criterion of 10 $ \ sigma $, we report no significant detection in any of the lenses. using the sensitivity function at the 10 - $ \ sigma $ level, we have calculated the predicted number of detectable cold dark matter ( cdm ) line - of - sight haloes to be $ \ mu _ { l } = 1. 17 \ pm1. 08 $, in agreement with our null detection. assuming a detection sensitivity that improved to the level implied by a 5 - $ \ sigma $ threshold, the expected number of detectable line - of - sight haloes rises to $ \ mu _ l = 9. 0 \ pm3. 0 $. whilst the current data find zero detections at this sensitivity level ( which has a probability of p $ ^ { { \ rm5 } \ sigma } _ { { \ rm cdm } } ( n _ { \ rm det } = 0 ) $ = 0. 0001 and would be in strong tension with the cdm framework ), we find that such a low detection threshold leads to many spurious detections and non - detections and therefore the current lack of detections is unreliable and requires data with improved sensitivity. combining this sample with a subsample of 11 slacs lenses, we constrain the half - mode mass to be $ \ log $ ( m $ _ { \ rm hm } ) < 12. 26 $ at the 2 - $ \ sigma $ level. the latter is consistent with resonantly produced sterile neutrino masses m $ _ { \ rm s } < 0. 8 $ kev at any value of the lepton asymmetry at the 2 - $ \ sigma $ level. | arxiv:1811.03627 |
we study the phase diagram of ultracold bosons in an optical lattice near a feshbach resonance. depending on the boson density, the strength of the optical lattice potential and the detuning from resonance, the ground state can be a mott insulator, a superfluid phase with both an atomic and a molecular condensate, or a superfluid phase with only a molecular condensate. mott insulator to superfluid transitions can be induced either by decreasing the strength of the optical lattice potential or by varying the detuning from the feshbach resonance. quite generally, we find that for a commensurate density the ground - state may undergo several insulator - superfluid or superfluid - insulator transitions as the magnetic field is varied through the resonance. | arxiv:cond-mat/0406396 |
we discuss the impact of matter effects in the d0 - d0bar system. we show that such effects could, in principle, be measured, but that they cannot be used to probe the mass difference x _ d or the lifetime difference y _ d. this occurs because the mixing effects and the matter effects decouple at short times. we also comment briefly on the b systems. | arxiv:hep-ph/0007214 |
the 2d half - filled kondo lattice model with exchange j and nearest neighbor hopping t is considered. it is shown that this model belongs to a class of hamiltonians for which zero - temperature auxiliary field monte carlo methods may be efficiently applied. we compute the staggered moment, spin and quasiparticle gaps on lattice sizes up to 12 x 12. the competition between the rkky interaction and kondo effect leads to a continuous quantum phase transition between antiferromagnetic and spin - gaped insulators. this transition occurs at j / t = 1. 45 \ pm 0. 05. | arxiv:cond-mat/9904178 |
topological point defects on orientationally ordered spheres, and on deformable fluid vesicles have been partly motivated by their potential applications in creating super - atoms with directional bonds through functionalization of the " bald - spots " created by topological point defects, thus paving the way for atomic chemistry at micron scales. we show that singular wall defects, topologically unstable " bald lines " in two dimensions, are stabilized near the order - disorder transition on a sphere. we attribute their stability to free - energetic considerations, which override those of topological stability. | arxiv:2003.09222 |
two permutations in a class are wilf - equivalent if, for every size, $ n $, the number of permutations in the class of size $ n $ containing each of them is the same. those infinite classes that have only one equivalence class in each size for this relation are characterised provided either that they avoid at least one permutation of size 3, or at least three permutations of size 4. | arxiv:1904.05500 |
we investigate the problem of fair recommendation in the context of two - sided online platforms, comprising customers on one side and producers on the other. traditionally, recommendation services in these platforms have focused on maximizing customer satisfaction by tailoring the results according to the personalized preferences of individual customers. however, our investigation reveals that such customer - centric design may lead to unfair distribution of exposure among the producers, which may adversely impact their well - being. on the other hand, a producer - centric design might become unfair to the customers. thus, we consider fairness issues that span both customers and producers. our approach involves a novel mapping of the fair recommendation problem to a constrained version of the problem of fairly allocating indivisible goods. our proposed fairrec algorithm guarantees at least maximin share ( mms ) of exposure for most of the producers and envy - free up to one item ( ef1 ) fairness for every customer. extensive evaluations over multiple real - world datasets show the effectiveness of fairrec in ensuring two - sided fairness while incurring a marginal loss in the overall recommendation quality. | arxiv:2002.10764 |
recent work on 3d - aware image synthesis has achieved compelling results using advances in neural rendering. however, 3d - aware synthesis of face dynamics hasn ' t received much attention. here, we study how to explicitly control generative model synthesis of face dynamics exhibiting non - rigid motion ( e. g., facial expression change ), while simultaneously ensuring 3d - awareness. for this we propose a controllable radiance field ( corf ) : 1 ) motion control is achieved by embedding motion features within the layered latent motion space of a style - based generator ; 2 ) to ensure consistency of background, motion features and subject - specific attributes such as lighting, texture, shapes, albedo, and identity, a face parsing net, a head regressor and an identity encoder are incorporated. on head image / video data we show that corfs are 3d - aware while enabling editing of identity, viewing directions, and motion. | arxiv:2210.05825 |
the interplay of electronic and nuclear degrees of freedom presents an outstanding problem in condensed matter physics and chemistry. computational challenges arise especially for large systems, long time scales, in nonequilibrium, or in systems with strong correlations. in this work, we show how downfolding approaches facilitate complexity reduction on the electronic side and thereby boost the simulation of electronic properties and nuclear motion - in particular molecular dynamics ( md ) simulations. three different downfolding strategies based on constraining, unscreening, and combinations thereof are benchmarked against full density functional calculations for selected charge density wave ( cdw ) systems, namely 1h - tas $ _ 2 $, 1t - tise $ _ 2 $, 1h - nbs $ _ 2 $, and a one - dimensional carbon chain. we find that the downfolded models can reproduce potential energy surfaces on supercells accurately and facilitate computational speedup in md simulations by about five orders of magnitude in comparison to purely ab initio calculations. for monolayer 1h - tas $ _ 2 $ we report classical replica exchange and quantum path integral md simulations, revealing the impact of thermal and quantum fluctuations on the cdw transition. | arxiv:2303.07261 |
we give a definition of the clifford algebra of an antiautomorphism of a central simple algebra, and compute it for the algebras of degree 2. | arxiv:math/0608625 |
we calculate the three gauge - boson production in the standard model at fermilab tevatron energies. at $ \ sqrt s = 2 $ tev in $ p \ bar p $ collisions, the cross sections for the triple gauge - boson production are typically of order 10 femtobarns ( fb ). for the pure leptonic final states from the gauge - boson decays and with some minimal cuts on final state photons, the cross sections for $ p \ bar p \ rightarrow w ^ \ pm \ gamma \ gamma, z \ gamma \ gamma $ and $ w ^ + w ^ - \ gamma $ processes are of order a few fb, resulting in a few dozen clean leptonic events for an integrated luminosity of 10 fb $ ^ { - 1 } $. the pure leptonic modes from other gauge - boson channels give significantly smaller rate. especially, the trilepton modes from $ w ^ + w ^ - w ^ \ pm $ and $ t \ bar t w ^ \ pm \ rightarrow w ^ + w ^ - w ^ \ pm $ yield a cross section of order 0. 1 fb if there is no significant higgs boson contribution. for a higgs boson with $ m _ h ^ { } \ simeq 2m _ z ^ { } $, the triple massive - gauge - boson production rate could be enhanced by a factor of $ 4 - 6 $. | arxiv:hep-ph/9507409 |
the implications of the angle - resolved photoemission spectroscopy ( arpes ) on the issue of spin - charge separation are discussed from the viewpoint of slave - particle rvb theories. it is pointed out that the non - local phase string is essential to reproduce the two - peak structure experimentally observed in srcuo _ 2. the comparison between 1d and 2d cases is also made. | arxiv:cond-mat/9702212 |
it is argued that the classical local inertial frame used to define rotational states of quantum systems is only approximate, and that geometry itself must also be rotationally quantized at the planck scale. a lorentz invariant statistical model of correlations in quantum geometry on larger scales predicts spacelike correlations that describe rotational fluctuations in the inertial frame. fluctuations are estimated to significantly affect the gravity of quantum field states on a macroscopic scale, characterized by the chandrasekhar radius. it is suggested that the cosmological constant might be a signature of exotic rotational correlations entangled with the strong interaction vacuum, and have a value determined entirely by planck scale quantum gravity and standard model fields. | arxiv:1509.07997 |
triboelectric nanogenerators ( tengs ) are an emerging mechanical energy harvesting technology that was recently demonstrated. due to their flexibility, they can be fabricated in various configurations and consequently have a large number of applications. here, we present a study on the influence of the thickness of the triboelectric layer and of the contact surface area between two triboelectrical materials on the electric signals generated by a teng. using the pdms - nylon tribo - pair, and varying the thickness of the pdms layer, we demonstrate that the generated voltage decreases with increasing thickness. however, the maximum generated current presents an inverse behaviour, increasing with increasing pdms thickness. the maximum output power initially increases with increasing pdms thickness up to 32 um, followed by a sharp decrease. using the same tribo - pair ( but now with a constant pdms thickness ), we verified that increasing the contact surface area between the two tribo - materials increases the electrical signals generated from the triboelectric effect. | arxiv:1803.10070 |
we study the influence of ferromagnetic nonlocal exchange on correlated electrons in terms of a $ su ( 2 ) $ - hubbard - heisenberg model and address the interplay of on - site interaction induced local moment formation and the competition of ferromagnetic direct and antiferromagnetic kinetic exchange interactions. in order to simulate thermodynamic properties of the system in a way that largely accounts for the on - site interaction driven correlations in the system, we advance the correlated variational scheme introduced in [ m. sch \ " uler et al., phys. rev. lett. 111, 036601 ( 2013 ) ] to account for explicitily symmetry broken electronic phases by introducing an auxiliary magnetic field. after benchmarking the method against exact solutions of a finite system, we study the $ su ( 2 ) $ - hubbard - heisenberg model on a square lattice. we obtain the $ u $ - $ j $ finite temperature phase diagram of a $ su ( 2 ) $ - hubbard - heisenberg model within the correlated variational approach and compare to static mean field theory. while the generalized variational principle and static mean field theory yield transitions from dominant ferromagnetic to antiferromagnetic correlations in similar regions of the phase diagram, we find that the nature of the associated phase tranistions differs between the two approaches. the fluctuations accounted for in the generalized variational approach render the transitions continuous, while static mean field theory predicts discontinuous transitions between ferro - and antiferromagnetically ordered states. | arxiv:1911.05420 |
this paper is concerned with a cubic nonlinear schr \ " odinger system modeling the interaction between an optical beam and its third harmonic in a material with kerr - type nonlinear response. we are mainly interested in the so - called energy - critical case, that is, in dimension four. our main result states that radially symmetric solutions with initial energy below that of the ground states but with kinetic energy above that of the ground states must blow - up in finite time. the proof of this result is based on the convexity method. as an independent interest we also establish the existence of ground state solutions, that is, solutions that minimize some action functional. in order to obtain our existence results we use the concentration - compactness method combined with variational arguments. as a byproduct, we also obtain the best constant in a vector critical sobolev - type inequality. | arxiv:2503.14210 |
conversations emerge as the primary media for exchanging ideas and conceptions. from the listener ' s perspective, identifying various affective qualities, such as sarcasm, humour, and emotions, is paramount for comprehending the true connotation of the emitted utterance. however, one of the major hurdles faced in learning these affect dimensions is the presence of figurative language, viz. irony, metaphor, or sarcasm. we hypothesize that any detection system constituting the exhaustive and explicit presentation of the emitted utterance would improve the overall comprehension of the dialogue. to this end, we explore the task of sarcasm explanation in dialogues, which aims to unfold the hidden irony behind sarcastic utterances. we propose moses, a deep neural network, which takes a multimodal ( sarcastic ) dialogue instance as an input and generates a natural language sentence as its explanation. subsequently, we leverage the generated explanation for various natural language understanding tasks in a conversational dialogue setup, such as sarcasm detection, humour identification, and emotion recognition. our evaluation shows that moses outperforms the state - of - the - art system for sed by an average of ~ 2 % on different evaluation metrics, such as rouge, bleu, and meteor. further, we observe that leveraging the generated explanation advances three downstream tasks for affect classification - an average improvement of ~ 14 % f1 - score in the sarcasm detection task and ~ 2 % in the humour identification and emotion recognition task. we also perform extensive analyses to assess the quality of the results. | arxiv:2211.11049 |
. | arxiv:0808.1305 |
free - form strong - lensing ( sl ) mass reconstructions typically suffer from overfitting, which manifest itself as false - positive small - scale fluctuations. we present a new free - form maximum - entropy reconstruction ( $ { \ tt mars } $ ) method without the assumption that light traces mass ( ltm ). the $ { \ tt mars } $ algorithm enables us to achieve excellent convergence in source positions ~ 0. 001 $ " $, minimize spurious small - scale fluctuations, and provide a quasi - unique solution independently of initial conditions. our method is tested with the publicly available synthetic sl data $ { \ tt ff - sims } $ and the comparison with the truth shows that the reconstruction quality is on a par with those of the best - performing ltm methods published in the literature, which have been demonstrated to outperform the existing free - form methods. in terms of the radial mass profile reconstruction, we achieve $ < 1 $ % agreements with the truth for the regions constrained by the multiple images. finally, we apply $ { \ tt mars } $ to a1689 and find that the cluster mass in the sl regime is dominated by the primary halo centered on the brightest cluster galaxy and the weaker secondary halo also coincident with the bright cluster member ~ 160 kpc northeast. within the sl field, the a1689 radial profile is well - described by a navarro - frenk - white ( nfw ) profile with $ c _ { 200 } = 5. 53 \ pm0. 77 $ and $ r _ s = 538 ^ { + 90 } _ { - 100 } $ kpc and we find no evidence that a1689 is over - concentrated. | arxiv:2202.10489 |
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