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loading classical data into quantum registers is one of the most important primitives of quantum computing. while the complexity of preparing a generic quantum state is exponential in the number of qubits, in many practical tasks the state to prepare has a certain structure that allows for faster preparation. in this paper, we consider quantum states that can be efficiently represented by ( reduced ) decision diagrams, a versatile data structure for the representation and analysis of boolean functions. we design an algorithm that utilises the structure of decision diagrams to prepare their associated quantum states. our algorithm has a circuit complexity that is linear in the number of paths in the decision diagram. numerical experiments show that our algorithm reduces the circuit complexity by up to 31. 85 % compared to the state - of - the - art algorithm, when preparing generic $ n $ - qubit states with different degrees of non - zero amplitudes. additionally, for states with sparse decision diagrams, including the initial state of the quantum byzantine agreement protocol, our algorithm reduces the number of cnots by 86. 61 % $ \ sim $ 99. 9 %.
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arxiv:2206.08588
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motivated by recent works in which the fzz duality plays an important role, we revisit the computation of correlation functions in the sine - liouville field theory. we present a direct computation of the three - point function, the simplest to the best of our knowledge, and give expressions for the $ n $ - point functions in terms of integrated liouville theory correlators. this leads us to discuss the relation to the $ h ^ + _ 3 $ wzw - liouville correspondence, especially in the case in which spectral flow is taken into account. we explain how these results can be used to study scattering amplitudes of winding string states in ads $ _ 3 $.
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arxiv:2110.04197
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we introduce a time - domain framework for efficient multichannel speech enhancement, emphasizing low latency and computational efficiency. this framework incorporates two compact deep neural networks ( dnns ) surrounding a multichannel neural wiener filter ( nwf ). the first dnn enhances the speech signal to estimate nwf coefficients, while the second dnn refines the output from the nwf. the nwf, while conceptually similar to the traditional frequency - domain wiener filter, undergoes a training process optimized for low - latency speech enhancement, involving fine - tuning of both analysis and synthesis transforms. our research results illustrate that the nwf output, having minimal nonlinear distortions, attains performance levels akin to those of the first dnn, deviating from conventional wiener filter paradigms. training all components jointly outperforms sequential training, despite its simplicity. consequently, this framework achieves superior performance with fewer parameters and reduced computational demands, making it a compelling solution for resource - efficient multichannel speech enhancement.
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arxiv:2401.07882
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this article introduces and investigates a refinement of alternating sign trapezoids by means of catalan objects and motzkin paths. alternating sign trapezoids are a generalisation of alternating sign triangles, which were recently introduced by ayyer, behrend and fischer. we show that the number of alternating sign trapezoids associated with a catalan object ( resp. motzkin path ) is a polynomial function in the length of the shorter base of the trapezoid. we also study the rational roots of the polynomials and formulate several conjectures and derive some partial results. lastly, we deduce a constant term identity for the refined counting of alternating sign trapezoids.
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arxiv:1804.10370
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because of mass assignment onto grid points in the measurement of the power spectrum using the fast fourier transform ( fft ), the raw power spectrum $ \ la | \ delta ^ f ( k ) | ^ 2 \ ra $ estimated with fft is not the same as the true power spectrum $ p ( k ) $. in this paper, we derive the formula which relates $ \ la | \ delta ^ f ( k ) | ^ 2 \ ra $ to $ p ( k ) $. for a sample of $ n $ discrete objects, the formula reads : $ \ la | \ delta ^ f ( k ) | ^ 2 \ ra = \ sum _ { \ vec n } [ | w ( \ kalias ) | ^ 2p ( \ kalias ) + 1 / n | w ( \ kalias ) | ^ 2 ] $, where $ w ( \ vec k ) $ is the fourier transform of the mass assignment function $ w ( \ vec r ) $, $ k _ n $ is the nyquist wavenumber, and $ \ vec n $ is an integer vector. the formula is different from that in some of previous works where the summation over $ \ vec n $ is neglected. for the ngp, cic and tsc assignment functions, we show that the shot noise term $ \ sum _ { \ vec n } 1 / n | w ( \ kalias ) | ^ 2 ] $ can be expressed by simple analytical functions. to reconstruct $ p ( k ) $ from the alias sum $ \ sum _ { \ vec n } | w ( \ kalias ) | ^ 2 p ( \ kalias ) $, we propose an iterative method. we test the method by applying it to an n - body simulation sample, and show that the method can successfully recover $ p ( k ) $. the discussion is further generalized to samples with observational selection effects.
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arxiv:astro-ph/0409240
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we analyze the collective motion of micro - organisms in the fluid and consider the problem of the red tide. the red tide is produced by the condensation of the micro - organisms, which might be a similar phenomenon to the condensation of the strings. we propose a model of the generation of the red tide. by considering the interaction between the micro - organisms mediated by the velocity fields in the fluid, we derive the van der waals type equation of state, where the generation of the red tide can be regarded as a phase transition from the gas of micro - organisms to the liquid. ( the number density of micro - organisms which generates the red tide is order estimated. )
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arxiv:hep-th/9508112
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unsupervised domain adaptation ( uda ) aims to improve the prediction performance in the target domain under distribution shifts from the source domain. the key principle of uda is to minimize the divergence between the source and the target domains. to follow this principle, many methods employ a domain discriminator to match the feature distributions. some recent methods evaluate the discrepancy between two predictions on target samples to detect those that deviate from the source distribution. however, their performance is limited because they either match the marginal distributions or measure the divergence conservatively. in this paper, we present a novel uda method that learns domain - invariant features that minimize the domain divergence. we propose model uncertainty as a measure of the domain divergence. our uda method based on model uncertainty ( muda ) adopts a bayesian framework and provides an efficient way to evaluate model uncertainty by means of monte carlo dropout sampling. empirical results on image recognition tasks show that our method is superior to existing state - of - the - art methods. we also extend muda to multi - source domain adaptation problems.
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arxiv:2211.08866
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we present bhasacitra, a dialect mapping system for south asia built on a database of linguistic studies of languages of the region annotated for topic and location data. we analyse language coverage and look towards applications to typology by visualising example datasets. the application is not only meant to be useful for feature mapping, but also serves as a new kind of interactive bibliography for linguists of south asian languages.
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arxiv:2105.14082
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we study hitting probabilities for $ \ mathbb { z } ^ d $ - extensions of gibbs - markov maps. the goal is to estimate, given a finite $ \ sigma \ subset \ mathbb { z } ^ d $ and $ p $, $ q \ in \ sigma $, the probability $ p _ { pq } $ that the process starting from $ p $ returns to $ \ sigma $ at site $ q $. our study generalizes the methods available for random walks. we are able to give in many settings ( square integrable jumps, jumps in the basin of a l \ ' evy or cauchy random variable ) asymptotics for the transition matrix $ ( p _ { pq } ) _ { p, q \ in \ sigma } $ when the elements of $ \ sigma $ are far apart. we use three main tools : a variant of the balayage identity using a transfer operator as a markov transition kernel, a study inspired from fast - slow systems and the hitting time of small sets in hyperbolic systems to relate transfer operators and the transition matrices we seek to compute, and finally fourier transform and perturbations of transfer operators \ textit { \ ` a la } nagaev - guivarc ' h to effectively compute these transition matrices in an asymptotic regime.
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arxiv:2112.08339
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we will present a review of the most interesting results on rare b decays from the b factories, based on the data collected by the babar and belle detectors at asymmetric $ e ^ + e ^ - $ colliders at the center of mass energy of the $ \ upsilon ( 4s ) $ resonance.
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arxiv:0905.2503
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we present research on radiative decays of vector ( $ j ^ { pc } = 1 ^ { - - } $ ) to pseudoscalar ( $ j ^ { pc } = 0 ^ { - + } $ ) particles ( $ u $, $ d $, $ s $, $ c $, $ b $, $ t $ quark system ) using broken symmetry techniques in the infinite momentum frame and equal time commutation relations and the $ su ( 6 ) $ lie algebra and conducted without ascribing any specific form to meson quark structure or intra - quark interactions. we utilize the physical electromagnetic current $ j _ { em } ^ { \ mu } ( 0 ) $ including its singlet $ u ( 1 ) $ term and focus on the $ su ( 6 ) $ $ 35 $ - plet. we derive new relations involving the electromagnetic current ( including its singlet - - proportional to the $ su ( 6 ) $ singlet ). remarkably, we find that the electromagnetic current singlet plays an intrinsic role in understanding the physics of radiative decays and that the charged and neutral $ \ rho $ meson radiative decays into $ \ pi \, \ gamma $ are due entirely to the singlet term in $ j _ { em } ^ { \ mu } ( 0 ) $. although there is insufficient radiative decay experimental data available at this time, parametrization of possible predicted values of $ \ gamma ( { { { d } } ^ { * } } ^ { 0 } \ rightarrow d ^ { 0 } \, \ gamma ) $ is made. for conciseness and self - containment, we compute all $ su ( 6 ) $ lie algebra simple roots, positive roots, weights and fundamental weights which allow the construction of all $ su ( 6 ) $ representations. we also derive all non - zero $ su ( 6 ) $ generator commutators and anti - commutators - - - useful for further research on grand unified theories.
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arxiv:1902.00853
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detection and tracking of vehicles captured by traffic surveillance cameras is a key component of intelligent transportation systems. we present an improved version of our algorithm for detection of 3d bounding boxes of vehicles, their tracking and subsequent speed estimation. our algorithm utilizes the known geometry of vanishing points in the surveilled scene to construct a perspective transformation. the transformation enables an intuitive simplification of the problem of detecting 3d bounding boxes to detection of 2d bounding boxes with one additional parameter using a standard 2d object detector. main contribution of this paper is an improved construction of the perspective transformation which is more robust and fully automatic and an extended experimental evaluation of speed estimation. we test our algorithm on the speed estimation task of the brnocompspeed dataset. we evaluate our approach with different configurations to gauge the relationship between accuracy and computational costs and benefits of 3d bounding box detection over 2d detection. all of the tested configurations run in real - time and are fully automatic. compared to other published state - of - the - art fully automatic results our algorithm reduces the mean absolute speed measurement error by 32 % ( 1. 10 km / h to 0. 75 km / h ) and the absolute median error by 40 % ( 0. 97 km / h to 0. 58 km / h ).
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arxiv:2003.13137
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we introduce a reversible markovian coagulation - fragmentation process on the set of partitions of $ \ { 1, \ ldots, l \ } $ into disjoint intervals. each interval can either split or merge with one of its two neighbors. the invariant measure can be seen as the gibbs measure for a homogeneous pinning model \ cite { cf : gbbook }. depending on a parameter $ \ lambda $, the typical configuration can be either dominated by a single big interval ( delocalized phase ), or be composed of many intervals of order $ 1 $ ( localized phase ), or the interval length can have a power law distribution ( critical regime ). in the three cases, the time required to approach equilibrium ( in total variation ) scales very differently with $ l $. in the localized phase, when the initial condition is a single interval of size $ l $, the equilibration mechanism is due to the propagation of two " fragmentation fronts " which start from the two boundaries and proceed by power - law jumps.
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arxiv:1107.3227
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though much is known about $ { \ bf s } $ - lecture hall polytopes, there are still many unanswered questions. in this paper, we show that $ { \ bf s } $ - lecture hall polytopes satisfy the integer decomposition property ( idp ) in the case of monotonic $ { \ bf s } $ - sequences. given restrictions on a monotonic $ { \ bf s } $ - sequence, we discuss necessary and sufficient conditions for the fano, reflexive and gorenstein properties. additionally, we give a construction for producing gorenstein / idp lecture hall polytopes.
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arxiv:1608.03934
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coupling fundamental quarks to qcd in the dual string representation corresponds to adding the open string sector. flavors therefore should be represented by space - time filling d - branes in the dual 5d closed string background. this requires several interesting properties of d - branes in ads. d - branes have to be able to end in thin air in order to account for massive quarks, which only live in the uv region. they must come in distinct sets, representing the chiral global symmetry, with a bifundamental field playing the role of the chiral condensate. we show that these expectations are born out in several supersymmetric examples. to analyze most of these properties it is not necessary to go beyond the probe limit in which one neglects the backreaction of the flavor d - branes.
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arxiv:hep-th/0205236
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because of the negative inclination of the solid - liquid phase separation line in water, ice ih melts on compression. on further increase in pressure the liquid water transforms into a high density metastable glassy state, characterized by a rapid approach to zero diffusion coefficient and an absence of any crystalline order in the static structure factor. the vitrification is found to occur even at high temperatures ( t > 250 k ). we study this glass transition process at four temperatures ( 80 k, 250 k, 300 k and 320 k ). the transition pressure increases with increase in temperature, as expected. interestingly, we find that the total entropy of the system exhibits a sharp crossover near the glass transition pressure where the diffusion of water goes to zero. the diffusion coefficient shows an exponential dependence on the properly defined excess entropy. in an interesting result not reported before, we find a pressure induced realignment of water molecules resulting in two well separated peaks in the o - o - o angle distribution among neighbouring molecules. the difference between the positions of these two peaks undergoes a sharp change at the vitrification pressure suggesting that it can serve as an appropriate order parameter to detect the glass transition point.
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arxiv:2104.10566
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alignment and orientation of molecules by intense, ultrashort laser fields are crucial for a variety of applications in physics and chemistry. these include control of high harmonics generation, molecular orbitals tomography, control of molecular photoionization and dissociation processes, production of " molecular movies " with the help of x - ray free - electron laser sources and ultrafast electron diffraction of relativistic electrons. while the dynamics of laser - induced molecular alignment has been extensively studied and demonstrated, molecular orientation is a much more challenging task, especially for asymmetric - top molecules. here we report the first experimental demonstration of a field - free, all - optical three - dimensional orientation of asymmetric - top molecules by means of phase - locked cross - polarized two - color laser pulses. in addition to the conventional integrated orientation factor, we report the differential degree of orientation which is not amenable to optical measurements, but is readily accessible in our angle - resolved imaging technique. our scheme applies to a wide class of asymmetric molecules and opens new ways towards controlling their orientation, eventually leading to direct imaging of structure of gas - phase molecules using advanced free electron laser beams with extremely high spatiotemporal resolution.
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arxiv:1803.07823
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in this paper, we are concerned with a nonlinear optimal control problem of ordinary differential equations. we consider a discretization of the problem with the discontinuous galerkin method with arbitrary order $ r \ in \ mathbb { n } \ cup \ { 0 \ } $. under suitable regularity assumptions on the cost functional and solutions of the state equations, we provide sharp estimates for the error of the approximate solutions. numerical experiments are presented supporting the theoretical results.
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arxiv:1905.12816
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given a singular variety i discuss the relations between quantum cohomology of its resolution and smoothing. in particular, i explain how toric degenerations helps with computing gromov - - witten invariants, and the role of this story in fanosearch programme. the challenge is to formulate enumerative symplectic geometry of complex $ 3 $ - folds in a way suitable for extracting invariants under blowups, contractions, and transitions.
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arxiv:1809.02737
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the higgs production and decay rates offer a new way to probe new physics beyond the standard model. while dynamics aiming at alleviating the hierarchy problem generically predict deviations in the higgs rates, the current experimental analyses cannot resolve the long - and short - distance contributions to the gluon fusion process and thus cannot access directly the coupling between the higgs and the top quark. we investigate the production of a boosted higgs in association with a high - transverse momentum jet as an alternative to the $ t \ bar { t } h $ channel to pin down this crucial coupling. presented first in the context of an effective field theory, our analysis is then applied to models of partial compositeness at the tev scale and of natural supersymmetry.
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arxiv:1312.3317
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we suggest a disordered traffic flow model that captures many features of traffic flow. it is an extension of the nagel - schreckenberg ( nasch ) stochastic cellular automata for single line vehicular traffic model. it incorporates random acceleration and deceleration terms that may be greater than one unit. our model leads under its intrinsic dynamics, for high values of braking probability $ p $, to a constant flow at intermediate densities without introducing any spatial inhomogeneities. for a system of fast drivers $ p \ to 0 $, the model exhibits a density wave behavior that was observed in car following models with optimal velocity. the gap of the disordered model we present exhibits, for high values of $ p $ and random deceleration, at a critical density, a power law distribution which is a hall mark of a self organized criticality phenomena.
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arxiv:physics/0507168
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graph classification, aiming at learning the graph - level representations for effective class assignments, has received outstanding achievements, which heavily relies on high - quality datasets that have balanced class distribution. in fact, most real - world graph data naturally presents a long - tailed form, where the head classes occupy much more samples than the tail classes, it thus is essential to study the graph - level classification over long - tailed data while still remaining largely unexplored. however, most existing long - tailed learning methods in visions fail to jointly optimize the representation learning and classifier training, as well as neglect the mining of the hard - to - classify classes. directly applying existing methods to graphs may lead to sub - optimal performance, since the model trained on graphs would be more sensitive to the long - tailed distribution due to the complex topological characteristics. hence, in this paper, we propose a novel long - tailed graph - level classification framework via collaborative multi - expert learning ( come ) to tackle the problem. to equilibrate the contributions of head and tail classes, we first develop balanced contrastive learning from the view of representation learning, and then design an individual - expert classifier training based on hard class mining. in addition, we execute gated fusion and disentangled knowledge distillation among the multiple experts to promote the collaboration in a multi - expert framework. comprehensive experiments are performed on seven widely - used benchmark datasets to demonstrate the superiority of our method come over state - of - the - art baselines.
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arxiv:2308.16609
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the large area telescope ( lat ) instrument on board the fermi satellite consists of a multi - layer silicon - strip tracker interleaved with tungsten converters ( tkr ), followed by a csi crystal hodoscopic calorimeter ( cal ). sixteen tkr and cal modules are assembled in a 4 $ \ times $ 4 array. a segmented anticoincidence plastic scintillator ( acd ) surrounds the tkrs. the primary cosmic - ray electron / positron energy spectrum has been measured from 20 gev to 1 tev using a dedicated event analysis that ensures efficient electron detection and reduced hadron contamination. results from detailed monte carlo simulations have been used to reconstruct the observed energy spectrum to the primary cosmic ray spectrum. we present here details of the analysis procedure and the energy spectrum reconstruction.
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arxiv:0907.0638
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the eye fixation patterns of human observers are a fundamental indicator of the aspects of an image to which humans attend. thus, manipulating fixation patterns to guide human attention is an exciting challenge in digital image processing. here, we present a new model for manipulating images to change the distribution of human fixations in a controlled fashion. we use the state - of - the - art model for fixation prediction to train a convolutional neural network to transform images so that they satisfy a given fixation distribution. for network training, we carefully design a loss function to achieve a perceptual effect while preserving naturalness of the transformed images. finally, we evaluate the success of our model by measuring human fixations for a set of manipulated images. on our test images we can in - / decrease the probability to fixate on selected objects on average by 43 / 22 % but show that the effectiveness of the model depends on the semantic content of the manipulated images.
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arxiv:1712.06492
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detection of contrast adjustments in the presence of jpeg postprocessing is known to be a challenging task. jpeg post processing is often applied innocently, as jpeg is the most common image format, or it may correspond to a laundering attack, when it is purposely applied to erase the traces of manipulation. in this paper, we propose a cnn - based detector for generic contrast adjustment, which is robust to jpeg compression. the proposed system relies on a patch - based convolutional neural network ( cnn ), trained to distinguish pristine images from contrast adjusted images, for some selected adjustment operators of different nature. robustness to jpeg compression is achieved by training the cnn with jpeg examples, compressed over a range of quality factors ( qfs ). experimental results show that the detector works very well and scales well with respect to the adjustment type, yielding very good performance under a large variety of unseen tonal adjustments.
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arxiv:1805.11318
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due to its wide use in personal, but most importantly, professional contexts, email represents a valuable source of information that can be harvested for understanding, reengineering and repurposing undocumented business processes of companies and institutions. towards this aim, a few researchers investigated the problem of extracting process oriented information from email logs in order to take benefit of the many available process mining techniques and tools. in this paper we go further in this direction, by proposing a new method for mining process models from email logs that leverage unsupervised machine learning techniques with little human involvement. moreover, our method allows to semi - automatically label emails with activity names, that can be used for activity recognition in new incoming emails. a use case demonstrates the usefulness of the proposed solution using a modest in size, yet real - world, dataset containing emails that belong to two different process models.
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arxiv:1609.06127
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let $ g $ be a lie group with real semisimple lie algebra $ \ mathfrak { g } $. further let $ \ mathfrak { g } = \ mathfrak { k } \ oplus \ mathfrak { p } $ be a cartan decomposition. the maximal compact subgroup $ k \ subseteq g $ acts on $ \ mathfrak { p } $ via the adjoint representation and the convex hulls of the resulting orbits are the polar orbitopes. we prove that every polar orbitope is a spectrahedron by giving an explicit representation. in addition we give a new proof for the fact that the faces of a polar orbitope are, up to conjugation, given by the faces of the momentum polytope.
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arxiv:1611.05658
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irradiation of cuprate high - $ t _ c $ superconductors with light ions of moderate energy creates point defects that lead to a reduction or full suppression of the critical temperature. by shaping the ion flux with a stencil mask, nanostructures for emerging superconducting electronics can be fabricated. the 3 - dimensional shape of such defect landscapes is examined, based on calculations of full collision cascades and atom displacements. a relation between the calculated defect density and experimental values of the critical temperature $ t _ c $ in thin yba $ _ 2 $ cu $ _ 3 $ o $ _ { 7 - \ delta } $ films is etablished that allows to determine the distribution of local $ t _ c $ ' s and its 3 - dimensional visualization. the results confirm that, using 75 kev he $ ^ + $ ion irradiation and a stencil mask, well - defined patterns of non - superconducting material in the superconducting matrix can be produced with low blurring.
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arxiv:1905.11667
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this technical report introduces a novel approach to efficient computation in homological algebra over fields, with particular emphasis on computing the persistent homology of a filtered topological cell complex. the algorithms here presented rely on a novel relationship between discrete morse theory, matroid theory, and classical matrix factorizations. we provide background, detail the algorithms, and benchmark the software implementation in the eirene package.
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arxiv:1606.00199
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in solving the problem of finding a temperature distribution which, at zero temperature, corresponds to superfluidity, i. e., to nonzero energy, the author tried to quantize free energy. this was done on the basis of supersecondary quantization whose special case is the usual secondary quantization for bosons and with the help of which new representations of the schr \ " odinger equation were obtained. the supersecondary quantization allowed the author to construct a variational method whose zero approximation are the hartree - fock and bogolyubov - bcsch variational principles. this method works especially well in the case of not a large number of particles. the new quantization and the variational method are of general character and can be used in the quantum field theory.
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arxiv:cond-mat/0012498
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one of the predictions of the $ \ lambda $ cdm cosmological framework is the hierarchical formation of structure, giving rise to dark matter ( dm ) halos and subhalos. when the latter are massive enough they retain gas ( i. e., baryons ) and become visible. this is the case of the dwarf satellite galaxies in the milky way ( mw ). below a certain mass, halos may not accumulate significant amounts of baryons and remain completely dark. however, if dm particles are weakly interacting massive particles ( wimps ), we expect them to annihilate in subhalos, producing gamma rays which can be detected with the fermi satellite. using the three most recent point - source fermi large area telescope ( lat ) catalogs ( 3fgl, 2fhl and 3fhl ), we search for dm subhalo candidates among the unidentified sources, i. e., sources with no firm association to a known astrophysical object. we apply several selection criteria based on the expected properties of the dm - induced emission from subhalos, which allow us to significantly reduce the list of potential candidates. then, by characterizing the minimum detection flux of the instrument and comparing our sample to predictions from the via lactea ii ( vl - ii ) n - body cosmological simulation, we place conservative and robust constraints on the $ \ langle \ sigma v \ rangle - m _ { dm } $ parameter space. for annihilation via the $ \ tau ^ + \ tau ^ - $ channel, we put an upper limit of $ 4 \ times 10 ^ { - 26 } ~ ( 5 \ times 10 ^ { - 25 } ) ~ cm ^ 3 ~ s ^ { - 1 } $ for a mass of 10 ( 100 ) gev. a critical improvement over previous treatments is the repopulation we made to include low - mass subhalos below the vl - ii mass resolution. with more advanced subhalo candidate filtering the sensitivity reach of our method can potentially improve these constraints by a factor 3 ( 2 ) for $ \ tau ^ + \ tau ^ - $ ( $ b \ bar { b } $ ) channel.
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arxiv:1906.11896
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in this work, we assess the potential detectability of solar panels made of silicon on an earth - like exoplanet as a potential technosignature. silicon - based photovoltaic cells have high reflectance in the uv - vis and in the near - ir, within the wavelength range of a space - based flagship mission concept like the habitable worlds observatory ( hwo ). assuming that only solar energy is used to provide the 2022 human energy needs with a land cover of ~ 2. 4 %, and projecting the future energy demand assuming various growth - rate scenarios, we assess the detectability with an 8 m hwo - like telescope. assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the ultraviolet - to - visible ( 0. 34 - 0. 52 um ), we find that several 100s of hours of observation time is needed to reach a snr of 5 for an earth - like planet around a sun - like star at 10pc, even with a solar panel coverage of ~ 23 % land coverage of a future earth. we discuss the necessity of concepts like kardeshev type i / ii civilizations and dyson spheres, which would aim to harness vast amounts of energy. even with much larger populations than today, the total energy use of human civilization would be orders of magnitude below the threshold for causing direct thermal heating or reaching the scale of a kardashev type i civilization. any extraterrrestrial civilization that likewise achieves sustainable population levels may also find a limit on its need to expand, which suggests that a galaxy - spanning civilization as imagined in the fermi paradox may not exist.
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arxiv:2405.04560
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we study zero - temperature quantum fluctuations in harmonically trapped one - dimensional interacting bose gases, using the self - consistent multiconfigurational time - dependent hartree method. we define $ phase $ $ fluctuations $ from the full single - particle density matrix by the spatial decay exponent of off - diagonal long - range order. in a regime of mesoscopic particle numbers and moderate contact couplings, we derive the spatial dependence of the amplitude of phase fluctuations, determined from the { \ em self - consistently } derived shape of the field operator orbitals and fock space orbital occupation amplitudes. it is shown that the phase fluctuations display a peak, which in turn corresponds to a dip of the first - order correlations in position space, akin to what has previously been obtained in the tonks - girardeau limit of very large interactions and low densities.
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arxiv:1701.06821
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the goal of the inverse reinforcement learning ( irl ) task is to identify the underlying reward function and the corresponding optimal policy from a set of expert demonstrations. while most irl algorithms ' theoretical guarantees rely on a linear reward structure, we aim to extend the theoretical understanding of irl to scenarios where the reward function is parameterized by neural networks. meanwhile, conventional irl algorithms usually adopt a nested structure, leading to computational inefficiency, especially in high - dimensional settings. to address this problem, we propose the first two - timescale single - loop irl algorithm under neural network parameterized reward and provide a non - asymptotic convergence analysis under overparameterization. although prior optimality results for linear rewards do not apply, we show that our algorithm can identify the globally optimal reward and policy under certain neural network structures. this is the first irl algorithm with a non - asymptotic convergence guarantee that provably achieves global optimality in neural network settings.
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arxiv:2503.17865
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we study the isoperimetric problem in euclidean space endowed with a density. we first consider piecewise constant densities and examine particular cases related to the characteristic functions of half - planes, strips and balls. we also consider continuous modification of gauss density in $ \ r ^ 2 $. finally, we give a list of related open questions.
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arxiv:0906.1256
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in shallow macrotidal ecosystems with large intertidal mudflats, the sediment - water coupling plays a crucial role in structuring the pelagic microbial food web functioning, since inorganic and organic matter and microbial components ( viruses and microbes ) of the microphytobenthic biofilm can be suspended toward the water column. two experimental bioassays were conducted in march and july 2008 to investigate the importance of biofilm input for the pelagic microbial and viral loops. pelagic inocula ( < 0. 6 $ \ mu $ and < 10 $ \ mu $ filtrates ) were diluted either with \ textless { } 30kda - ultrafiltered seawater or with this ultrafiltrate enriched with the respective size - fractionated benthic biofilm or with \ textless { } 30kda - benthic compounds ( bc ). the kinetics of heterotrophic nanoflagellates ( hnf ), bacteria and viruses were assessed together with bacterial and viral genomic fingerprints, bacterial enzymatic activities and viral life strategies. the experimental design allowed us to evaluate the effect of bc modulated by those of benthic size - fractionated microorganisms ( virus + bacteria, + hnf ). bc presented ( 1 ) in march, a positive effect on viruses and bacteria weakened by pelagic hnf. benthic microorganisms consolidated this negative effect and sustained the viral production together with a relatively diverse and uneven bacterial assemblage structure ; ( 2 ) in july, no direct impact on viruses but a positive effect on bacteria modulated by hnf, which indirectly enhanced viral multiplication. both effects were intensified by benthic microorganisms and bacterial assemblage structure became more even. hnf indirectly profited from bc more in march than in july. the microbial loop would be stimulated by biofilm during periods of high resources ( march ) and the viral loop during periods of depleted resources ( july ).
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arxiv:1412.7519
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machine learning and deep learning have shown great promise in mobile sensing applications, including human activity recognition. however, the performance of such models in real - world settings largely depends on the availability of large datasets that captures diverse behaviors. recently, studies in computer vision and natural language processing have shown that leveraging massive amounts of unlabeled data enables performance on par with state - of - the - art supervised models. in this work, we present selfhar, a semi - supervised model that effectively learns to leverage unlabeled mobile sensing datasets to complement small labeled datasets. our approach combines teacher - student self - training, which distills the knowledge of unlabeled and labeled datasets while allowing for data augmentation, and multi - task self - supervision, which learns robust signal - level representations by predicting distorted versions of the input. we evaluated selfhar on various har datasets and showed state - of - the - art performance over supervised and previous semi - supervised approaches, with up to 12 % increase in f1 score using the same number of model parameters at inference. furthermore, selfhar is data - efficient, reaching similar performance using up to 10 times less labeled data compared to supervised approaches. our work not only achieves state - of - the - art performance in a diverse set of har datasets, but also sheds light on how pre - training tasks may affect downstream performance.
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arxiv:2102.06073
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we obtain a quantitative estimate of bergman distance when $ \ omega \ subset \ mathbb { c } ^ n $ is a bounded domain with log - hyperconvexity index $ \ alpha _ l ( \ omega ) > \ frac { n - 1 + \ sqrt { ( n - 1 ) ( n + 3 ) } } { 2 } $, as well as the $ a ^ 2 ( \ log a ) ^ q $ - integrability of the bergman kernel $ k _ { \ omega } ( \ cdot, w ) $ when $ \ alpha _ l ( \ omega ) > 0 $.
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arxiv:2206.10133
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we propose a symmetry resolution of entanglement for categorical non - invertible symmetries ( cat - sree ) in ( 1 + 1 ) - dimensional cfts. the definition parallels that of group - like invertible symmetries, employing the concept of symmetric boundary states with respect to a categorical symmetry. our examination extends to rational cfts, where the behavior of cat - sree mirrors that of group - like invertible symmetries. we find that cat - sree can be defined if there is no obstruction to gauging the categorical symmetry, as happens in the case of group - like symmetries. we also provide instances of the breakdown of entanglement equipartition at the next - to - leading order in the cutoff expansion. our findings shed light on how the interplay between conformal boundary conditions and categorical symmetries lead to specific patterns in the entanglement entropy.
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arxiv:2402.06322
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in this paper we investigate the consequences of phantom crossing considering the perturbative dynamics in models with interaction in their dark sector. by mean of a general study of gauge - invariant variables in comoving gauge, we relate the sources of instabilities in the structure formation process with the phantom crossing. in order to illustrate these relations and its consequences in more detail, we consider a specific case of an holographic dark energy interacting with dark matter. we find that in spite of the model is in excellent agreement with observational data at background level, however it is plagued of instabilities in its perturbative dynamics. we reconstruct the model in order to avoid these undesirable instabilities, and we show that this implies a modification of the concordance model at background. also we find drastic changes on the parameters space in our model when instabilities are avoided.
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arxiv:1607.01806
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##trahedron, cube, octahedron, dodecahedron, or icosahedron. " in logic, the extension of a predicate is the set of all objects for which the predicate is true. further, the logical principle of extensionality judges two objects to objects to be equal if they satisfy the same external properties. since, by the axiom, two sets are defined to be equal if they satisfy membership, sets are extentional. jose ferreiros credits richard dedekind for being the first to explicitly state the principle, although he does not assert it as a definition : it very frequently happens that different things a, b, c... considered for any reason under a common point of view, are collected together in the mind, and one then says that they form a system s ; one calls the things a, b, c... the elements of the system s, they are contained in s ; conversely, s consists of these elements. such a system s ( or a collection, a manifold, a totality ), as an object of our thought, is likewise a thing ; it is completely determined when, for every thing, it is determined whether it is an element of s or not. = = = background = = = around the turn of the 20th century, mathematics faced several paradoxes and counter - intuitive results. for example, russell ' s paradox showed a contradiction of naive set theory, it was shown that the parallel postulate cannot be proved, the existence of mathematical objects that cannot be computed or explicitly described, and the existence of theorems of arithmetic that cannot be proved with peano arithmetic. the result was a foundational crisis of mathematics. the resolution of this crisis involved the rise of a new mathematical discipline called mathematical logic, which studies formal logic within mathematics. subsequent discoveries in the 20th century then stabilized the foundations of mathematics into a coherent framework valid for all mathematics. this framework is based on a systematic use of axiomatic method and on set theory, specifically zermelo – fraenkel set theory, developed by ernst zermelo and abraham fraenkel. this set theory ( and set theory in general ) is now considered the most common foundation of mathematics. = = = set equality based on first - order logic with equality = = = in first - order logic with equality ( see § axioms ), the axiom of extensionality states that two sets that contain the same elements are the same set. logic axiom : x = y z, ( z
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https://en.wikipedia.org/wiki/Equality_(mathematics)
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we present integral and xmm - newton observations of the prompt gamma - ray emission and the x - ray afterglow of grb030227, the first grb for which the quick localization obtained with the integral burst alert system ( ibas ) has led to the discovery of x - ray and optical afterglows. grb030227 had a duration of about 20 s and a peak flux of 1. 1 photons cm ^ - 2 s ^ - 1 in the 20 - 200 kev energy range. the time averaged spectrum can be fit by a single power law with photon index about 2 and we find some evidence for a hard to soft spectral evolution. the x - ray afterglow has been detected starting only 8 hours after the prompt emission, with a 0. 2 - 10 kev flux decreasing as t ^ - 1 from 1. 3x10e - 12 to 5x10e - 13 erg cm ^ - 2 s ^ - 1. the afterglow spectrum is well described by a power law with photon index 1. 94 + / - 0. 05 modified by a redshifted neutral absorber with column density of several 10e22 cm ^ - 2. a possible emission line at 1. 67 kev could be due to fe for a redshift z = 3, consistent with the value inferred from the absorption.
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arxiv:astro-ph/0304477
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hall effect measurements are important for elucidating the fundamental charge transport mechanisms and intrinsic mobility in organic semiconductors. however, hall effect studies frequently reveal an unconventional behavior that cannot be readily explained with the simple band - semiconductor hall effect model. here, we develop an analytical model of hall effect in organic field - effect transistors in a regime of coexisting band and hopping carriers. the model, which is supported by the experiments, is based on a partial hall voltage compensation effect, occurring because hopping carriers respond to the transverse hall electric field and drift in the direction opposite to the lorentz force acting on band carriers. we show that this can lead in particular to an underdeveloped hall effect observed in organic semiconductors with substantial off - diagonal thermal disorder. our model explains the main features of hall effect in a variety of organic semiconductors and provides an analytical description of hall mobility, carrier density and carrier coherence factor.
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arxiv:1601.05849
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in this note, we show that in planar pointsets determining many unit distances, these unit distances must span many directions. specifically, we show that a set of $ n $ points can determine only $ o ( n ^ { 4 / 3 } ) $ unit distances from a set of at most $ o ( n ^ { 1 / 3 } ) $ directions.
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arxiv:2504.04208
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we have found in [ 1 ] new conditions for a total neutrino conversion in the case of neutrino oscillations taking place in a medium, consisting of n = 2 ( or 3 ) alternating layers with constant densities $ n _ 1 $ and $ n _ 2 $. it is claimed in [ 4 ] that our results are particular case of enhancement of neutrino oscillations, which was suggested earlier by other authors and was widely discussed in the literature. we refute these claims, confirming the novelty of our results.
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arxiv:hep-ph/0504247
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nio6 octahedral tilts in the lanio3 / srtio3 superlattices are quantified using position averaged convergent beam electron diffraction in scanning transmission electron microscopy. it is shown that maintaining oxygen octahedra connectivity across the interface controls the octahedral tilts in the lanio3 layers, their lattice parameters and their transport properties. unlike films and layers that are connected on one side to the substrate, subsequent lanio3 layers in the superlattice exhibit a relaxation of octahedral tilts towards bulk values. this relaxation is facilitated by correlated tilts in srtio3 layers and is correlated with the conductivity enhancement of the lanio3 layers in the superlattices relative to individual films.
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arxiv:1301.7444
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we analyze the influence of disorder and strong correlations on the topology in two dimensional chern insulators. a mean field calculation in the half - filled haldane model with extended hubbard interactions and anderson disorder shows that disorder favors topology in the interacting case and extends the topological phase to a larger region of the hubbard parameters. in the absence of a staggered potential, we find a novel disorder - driven topological phase with chern number c = 1, with co - existence of topology with long range spin and charge orders. more conventional topological anderson insulating phases are also found in the presence of a finite staggered potential.
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arxiv:2307.16053
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a striking feature of our fundamentally indeterministic quantum universe is its quasiclassical realm - - the wide range of time place and scale in which the deterministic laws of classical physics hold. our quasiclassical realmis an emergent feature of the fundamental theories of our universe ' s quantum state and dynamics. there are many types of quasiclassical realms our universe could exhibit characterized by different variables, different levels of coarse - graining, different locations in spacetime, different classical physics, and different levels of classicality. we propose a measure of classicality for quasiclassical realms, we speculate on the observable consequences of different levels of classicality especially for information gathering and utilizing systems ( iguses ) such ourselves as observers of the universe.
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arxiv:2104.14465
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threshold effects in the estimation of parameters of non - linearly modulated, continuous - time, wide - band waveforms, are examined from a statistical physics perspective. these threshold effects are shown to be analogous to phase transitions of certain disordered physical systems in thermal equilibrium. the main message, in this work, is in demonstrating that this physical point of view may be insightful for understanding the interactions between two or more parameters to be estimated, from the aspects of the threshold effect.
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arxiv:1005.3620
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human - centered explainable ai ( hcxai ) advocates for the integration of social aspects into ai explanations. central to the hcxai discourse is the social transparency ( st ) framework, which aims to make the socio - organizational context of ai systems accessible to their users. in this work, we suggest extending the st framework to address the risks of social misattributions in large language models ( llms ), particularly in sensitive areas like mental health. in fact llms, which are remarkably capable of simulating roles and personas, may lead to mismatches between designers ' intentions and users ' perceptions of social attributes, risking to promote emotional manipulation and dangerous behaviors, cases of epistemic injustice, and unwarranted trust. to address these issues, we propose enhancing the st framework with a fifth ' w - question ' to clarify the specific social attributions assigned to llms by its designers and users. this addition aims to bridge the gap between llm capabilities and user perceptions, promoting the ethically responsible development and use of llm - based technology.
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arxiv:2403.17873
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a novel method for computing reachable sets is proposed in this paper. in the proposed method, a hamilton - jacobi - bellman equation with running cost functionis numerically solved and the reachable sets of different time horizons are characterized by a family of non - zero level sets of the solution of the hamilton - jacobi - bellman equation. in addition to the classical reachable set, by setting different running cost functions and terminal conditionsof the hamilton - jacobi - bellman equation, the proposed method allows to compute more generalized reachable sets, which are referred to as cost - limited reachable sets. in order to overcome the difficulty of solving the hamilton - jacobi - bellman equation caused by the discontinuity of the solution, a method based on recursion and grid interpolation is employed. at the end of this paper, some examples are taken to illustrate the validity and generality of the proposed method.
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arxiv:2107.11941
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the future of mobility - as - a - service ( maas ) should embrace an integrated system of ride - hailing, street - hailing and ride - sharing with optimised intelligent vehicle routing in response to a real - time, stochastic demand pattern. we aim to optimise routing policies for a large fleet of vehicles for street - hailing services, given a stochastic demand pattern in small to medium - sized road networks. a model - based dispatch algorithm, a high performance model - free reinforcement learning based algorithm and a novel hybrid algorithm combining the benefits of both the top - down approach and the model - free reinforcement learning have been proposed to route the \ emph { vacant } vehicles. we design our reinforcement learning based routing algorithm using proximal policy optimisation and combined intrinsic and extrinsic rewards to strike a balance between exploration and exploitation. using a large - scale agent - based microscopic simulation platform to evaluate our proposed algorithms, our model - free reinforcement learning and hybrid algorithm show excellent performance on both artificial road network and community - based singapore road network with empirical demands, and our hybrid algorithm can significantly accelerate the model - free learner in the process of learning.
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arxiv:2010.11738
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the quantum anomalous hall effect is defined as a quantized hall effect realized in a system without external magnetic field. quantum anomalous hall effect is a novel manifestation of topological structure in many - electron systems, and may have potential applications in future electronic devices. in recent years, quantum anomalous hall effect has been proposed theoretically and realized experimentally. in this review article, we provide a systematic overview of the theoretical and experimental developments in this field.
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arxiv:1508.07106
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the mergers of binary neutron stars, as well as black hole - neutron star systems, are expected to produce an electromagnetic counterpart that can be analyzed to infer the element synthesis that occurred in these events. we investigate one source of uncertainties pertinent to lanthanide - rich outflows : the nuclear inputs to rapid neutron capture nucleosynthesis calculations. we begin by examining thirty - two different combinations of nuclear inputs : eight mass models, two types of spontaneous fission rates, and two types of fission daughter product distributions. we find that such nuclear physics uncertainties typically generate at least one order of magnitude uncertainty in key quantities such as the nuclear heating ( one and a half orders of magnitude at one day post - merger ), the bolometric luminosity ( one order of magnitude at five days post - merger ), and the inferred mass of material from the bolometric luminosity ( factor of eight when considering the eight to ten days region ). since particular nuclear processes are critical for determining the electromagnetic signal, we provide tables of key nuclei undergoing $ \ beta $ - decay, $ \ alpha $ - decay, and spontaneous fission important for heating at different times, identifying decays that are common among the many nuclear input combinations.
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arxiv:2010.03668
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the cold spot, with an unusually cold region surrounded by a hot ring, is a statistically significant anomaly in the cosmic microwave background ( cmb ) sky. in this work we assess whether different sets of multiple subvoids based on the 2df - vst atlas cold spot galaxy redshift survey or a collapsing cosmic texture could have produced such an anomaly through a simultaneous search for their gravitational redshift and lensing signatures on the { \ it planck } cmb temperature anisotropies. we use patches with radii $ r = 10 ^ \ circ $ and $ r = 20 ^ \ circ $ to account for the inner cold region as well as the outer hot ring. as the void model, we explore two sets of $ \ lambda $ ltb templates characterized by different values of the model ' s free parameters, and a top - hat void template. we detect higher - than - expected gravitational redshift amplitudes for the first two sets, $ \ mathcal { a } _ { \ rm rs } = 5. 4 \ pm 1. 4 $ and $ \ mathcal { a } _ { \ rm rs } = 14. 4 \ pm 3. 8 $, and lower than expected for the top - hat model, $ \ mathcal { a } _ { \ rm rs } = 0. 3 \ pm 0. 1 $. the amplitudes for the lensing imprint are consistent with zero for all these subvoid models. the estimated amplitude for the texture imprint from the gravitational redshift measurement implies the energy scale of the texture, parametrized by $ \ epsilon $, to be $ \ epsilon = ( 7. 6 \ pm2. 0 ) \ times 10 ^ { - 5 } $, with no detection of the lensing trace. we note that the deviation of the subvoid amplitudes from unity and the inability of the texture and some of the void profiles to reproduce the hot ring indicate theoretical insufficiencies, either in the construction of the model or in the assumed gravitational and cosmological framework leading to the imprints for the structures.
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arxiv:2001.03995
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we present a brief description of the determination of the two - loop spin - dependent time - like splitting functions relevant for the nlo evolution of polarized fragmentation functions. our calculation based on the analytic continuation of the corresponding space - like results obtained within the light - cone gauge method proposed by curci, furmanski, and petronzio. as an application we present an analysis of polarized lambda production in e + e - and ep collisions.
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arxiv:hep-ph/9705415
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any cluster - tilted algebra is the relation extension of a tilted algebra. we present a method to, given the distribution of a cluster - tilting object in the auslander - reiten quiver of the cluster category, construct all tilted algebras whose relation extension is the endomorphism ring of this cluster - tilting object.
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arxiv:0902.1667
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for a real - world decision - making problem, the reward function often needs to be engineered or learned. a popular approach is to utilize human feedback to learn a reward function for training. the most straightforward way to do so is to ask humans to provide ratings for state - action pairs on an absolute scale and take these ratings as reward samples directly. another popular way is to ask humans to rank a small set of state - action pairs by preference and learn a reward function from these preference data. recently, preference - based methods have demonstrated substantial success in empirical applications such as instructgpt. in this work, we develop a theoretical comparison between these human feedback approaches in offline contextual bandits and show how human bias and uncertainty in feedback modelings can affect the theoretical guarantees of these approaches. through this, our results seek to provide a theoretical explanation for the empirical successes of preference - based methods from a modeling perspective.
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arxiv:2307.12975
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for a simple - root $ \ lambda $ - constacyclic code $ \ mathcal { c } $ over $ \ mathbb { f } _ q $, let $ \ langle \ rho \ rangle $ and $ \ langle \ rho, m \ rangle $ be the subgroups of the automorphism group of $ \ mathcal { c } $ generated by the cyclic shift $ \ rho $, and by the cyclic shift $ \ rho $ and the scalar multiplication $ m $, respectively. let $ n _ g ( \ mathcal { c } ^ \ ast ) $ be the number of orbits of a subgroup $ g $ of automorphism group of $ \ mathcal { c } $ acting on $ \ mathcal { c } ^ \ ast = \ mathcal { c } \ backslash \ { 0 \ } $. in this paper, we establish explicit formulas for $ n _ { \ langle \ rho \ rangle } ( \ mathcal { c } ^ \ ast ) $ and $ n _ { \ langle \ rho, m \ rangle } ( \ mathcal { c } ^ \ ast ) $. consequently, we derive a upper bound on the number of nonzero weights of $ \ mathcal { c } $. we present some irreducible and reducible $ \ lambda $ - constacyclic codes, which show that the upper bound is tight. a sufficient condition to guarantee $ n _ { \ langle \ rho \ rangle } ( \ mathcal { c } ^ \ ast ) = n _ { \ langle \ rho, m \ rangle } ( \ mathcal { c } ^ \ ast ) $ is presented.
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arxiv:2305.06505
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we study local activity and its opposite, local passivity, for linear systems and show that generically an eigenvalue of the system matrix with positive real part implies local activity. if all state variables are port variables we prove that the system is locally active if and only if the system matrix is not dissipative. local activity was suggested by leon chua as an indicator for the emergence of complexity of nonlinear systems. we propose an abstract scheme which indicates how local activity could be applied to nonlinear systems and list open questions about possible consequences for complexity.
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arxiv:1610.01294
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the gamma - ray large area space telescope ( glast ) is now being designed by a number of collaborating institutions. it will study the cosmic gamma radiation from 20 mev to 300 gev with high precision and sensitivity, greatly expanding on the important egret results. one of the key systems of the instrument, the anticoincidence detector ( acd ), is designed to reject the majority of charged particles, which are the background for any gamma - ray experiment. the acd of egret has suffered from the self - veto effect when the products of the high energy photon interactions in the instrument ' s calorimeter cause a veto signal in the anticoincidence detector ( backsplash effect ), resulting in the degradation of the efficiency for high energy ( > 5 gev ) gamma rays. to avoid this effect, the acd for glast is divided into many scintillating tiles with wave - shifting fiber readout. the design of this detector along with the beam test and simulation results are given in this paper.
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arxiv:astro-ph/9912138
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while the conducting cuo $ _ 2 $ planes in cuprate superconductors have been widely recognized as a crucial component in producing high superconducting $ t _ \ text { c } $, recent experimental and theoretical studies on ba $ _ { 2 - x } $ sr $ _ x $ cuo $ _ { 3 + } $ $ _ \ delta $ have also drawn much attention to the importance of cu - o chains in one - dimensional ( 1d ) cuprates. to better understand the cuprates containing cu - o chains, here we have studied the electronic, magnetic, and phonon properties of sr $ _ 2 $ cuo $ _ 3 $ bulk and films based on the spin - polarized density functional theory calculations. we first reproduced the typical mott insulator feature of the cuprate parent compound for bulk sr $ _ 2 $ cuo $ _ 3 $, and then built a sr $ _ 2 $ cuo $ _ 3 $ thin film with cu - o chains exposed on the surface to directly investigate their characteristics. different from the insulating bulk phase, the sr $ _ 2 $ cuo $ _ 3 $ surface shows interesting metallic properties. further electronic structure calculations reveal the existence of spin - polarized electron gas between surface sr atoms that strongly depends on the interchain coupling of cu spins. moreover, the phonon modes that involve the vibrations of in - chain and out - of - chain o atoms can induce strong charge and spin fluctuations in the surface layer of sr $ _ 2 $ cuo $ _ 3 $ film, which suggests significant multiple degree - of - freedom couplings that may be important for the superconductivity in 1d cuprates. our work provides a comprehensive viewpoint of the properties of cu - o chains in sr $ _ 2 $ cuo $ _ 3 $, facilitating a complete understanding of 1d cuprate superconductors.
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arxiv:2411.13301
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we consider the problem of generating automatic code given sample input - output pairs. we train a neural network to map from the current state and the outputs to the program ' s next statement. the neural network optimizes multiple tasks concurrently : the next operation out of a set of high level commands, the operands of the next statement, and which variables can be dropped from memory. using our method we are able to create programs that are more than twice as long as existing state - of - the - art solutions, while improving the success rate for comparable lengths, and cutting the run - time by two orders of magnitude. our code, including an implementation of various literature baselines, is publicly available at https : / / github. com / amitz25 / pccoder
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arxiv:1809.04682
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in this paper, we study the connectivity in one - dimensional ad hoc wireless networks with an fixed access point. in recent years, various closed expressions for the probability of connectivity on one - dimensional networks ( interval graphs ) have been derived by many researchers. we will provide some numerical validation for them by means of extensive simulations.
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arxiv:1203.0044
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the topic of a photon mass has received justified attention over the years with strong theoretical reasoning for its existence. we derive a full description of mode solutions in step - index optical fibres on the basis of proca ' s equation as a model for massive photons. the no - go theorem recently found in coaxial waveguides does not appear in the optical fibre case.
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arxiv:2302.12729
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in 1969 erdoes found a lower bound on the number of ( r + 1 ) - cliques sharing an edge in graphs with n vertices and t ( r, n ) + 1 edges, where t ( r, n ) is the size of the turan graph of order n and r color classes. we improve erdoes ' s bound and prove a related stability result.
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arxiv:math/0410217
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we explore the sensitivity to a non vanishing neutrino mass offered by dynamical observables, i. e., branching ratios and polarizations. the longitudinal polarization in the c. m. frame decreases by a 4 % for $ d ^ + \ rightarrow \ tau ^ + \ nu _ \ tau $ and $ m _ { \ nu _ \ tau } = 24 $ mev. taking advantage of the fact that the polarization is a lorentz variant quantity, we study the polarization effects in a boosted frame. by means of a neutrino beam, produced by a high velocity boosted parent able to flip the neutrino helicity, we find that an enhanced left - handed neutrino deficit, induced by a wigner rotation, appears.
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arxiv:hep-ph/9606218
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we briefly discuss some open problems and recent developments in the investigation of the origin and propagation of ultra high energy cosmic rays ( uhecrs ).
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arxiv:astro-ph/0512438
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this paper studies on - chip communication with non - ideal heat sinks. a channel model is proposed where the variance of the additive noise depends on the weighted sum of the past channel input powers. it is shown that, depending on the weights, the capacity can be either bounded or unbounded in the input power. a necessary condition and a sufficient condition for the capacity to be bounded are presented.
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arxiv:cs/0703154
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we study charge and heat transport in normal - metal / superconductor ( ns ) hybrid junction, based on a tilted anisotropic dirac material. using the extended blonder - tinkham - klapwijk formalism, the conductance spectra of ns borophane, a two - dimensional dirac semimetal with two tilted anisotropic dirac cones in its dispersion, is investigated. completely different from the usual normal - metal - superconductor junctions, in spite of the large mismatch in fermi wavevectores of the normal - metal and superconductor sides of the borophane ns junction, the electron - hole conversion happens with unit probability at normal incidences. furthermore, we demonstrate that in the heavily doped superconducting regime for heavily doped normal borophane, the electron - hole conversion happens with unit probability, approximately at any incident angle. the dependence of the andreev with fermi energy and bias voltage, enable us, selecting the retroconfiguration or specular configuration in types of andreev reflection processes. we numerically establish an anomalous behavior of thermal conductance in borophane. the tilting of the dirac cones gives rise to an anomalous behaviour in the thermal conductance of the ns hybrid junction of borophane, such that the thermal conductance decreases by increasing the temperature. our findings will have potential applications for transport and energy control in superconducting quantum interference devices and hybridized mesoscopic systems.
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arxiv:1901.11114
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while considerable progress has been made in the analysis of large systems containing a single type of coupled dynamical component ( e. g., coupled oscillators or coupled switches ), systems containing diverse components ( e. g., both oscillators and switches ) have received much less attention. we analyze large, hybrid systems of interconnected kuramoto oscillators and hopfield switches with positive feedback. in this system, oscillator synchronization promotes switches to turn on. in turn, when switches turn on they enhance the synchrony of the oscillators to which they are coupled. depending on the choice of parameters, we find theoretically coexisting stable solutions with either ( i ) incoherent oscillators and all switches permanently off, ( ii ) synchronized oscillators and all switches permanently on, or ( iii ) synchronized oscillators and switches that periodically alternate between the on and off states. numerical experiments confirm these predictions. we discuss how transitions between these steady state solutions can be onset deterministically through dynamic bifurcations or spontaneously due to finite - size fluctuations.
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arxiv:1306.1962
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multimedia streaming over http is no longer a niche research topic as it has entered our daily live. the common assumption is that it is deployed on top of the existing infrastructure utilizing application ( http ) and transport ( tcp ) layer protocols as is. interestingly, standards like mpeg ' s dynamic adaptive streaming over http ( dash ) do not mandate the usage of any specific transport protocol allowing for sufficient deployment flexibility which is further supported by emerging developments within both protocol layers. this paper investigates and evaluates the usage of advanced transport options for the dynamic adaptive streaming over http. we utilize a common test setup to evaluate http / 2. 0 and google ' s quick udp internet connections ( quic ) protocol in the context of dash - based services.
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arxiv:1606.00264
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we study the problem of characterizing the set of games that are consistent with observed equilibrium play. our contribution is to develop and analyze a new methodology based on convex optimization to address this problem for many classes of games and observation models of interest. our approach provides a sharp, computationally efficient characterization of the extent to which a particular set of observations constrains the space of games that could have generated them. this allows us to solve a number of variants of this problem as well as to quantify the power of games from particular classes ( e. g., zero - sum, potential, linearly parameterized ) to explain player behavior. we illustrate our approach with numerical simulations.
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arxiv:1603.01318
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we introduce and study a new type of ramsey - turan problems, a typical example of which is the following one : let c > 0 and g be a graph of sufficiently large order n with minimum degree > 3n / 4. if the edges of g are colored in blue or red, then for every 3 < k < ( 1 / 8 - c ) n, there exists a monochromatic cycle of length k.
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arxiv:1001.2078
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dynamic metasurface antennas ( dmas ) arise as a promising technology in the field of massive multiple - input multiple - output ( mmimo ) systems, offering the possibility of integrating a large number of antennas in a limited - - and potentially large - - aperture while keeping the required number of radio - frequency ( rf ) chains under control. although envisioned as practical realizations of mmimo systems, dmas represent a new paradigm in the design of signal processing techniques ( such as beamforming ) due to the constraints inherent to their physical implementation, for which no complete models are available yet. in this work, we propose a complete and electromagnetic - compliant narrowband communication model for a generic dma based system. specifically, the model accounts for : i ) the wave propagation and reflections throughout the waveguides that feed the antenna elements, ii ) the mutual coupling both through the air and the waveguides, and iii ) the insertion losses. also, we integrate the electromagnetic model in the conventional digital communication model, providing a complete and useful framework to design and characterize the performance of these systems. finally, the accuracy of the model is verified through full - wave simulations.
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arxiv:2212.11594
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this is a summary of the contributions presented in the heavy flavours working group of the dis2006 workshop.
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arxiv:hep-ph/0608118
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the center $ z ( \ mathcal { a } ) $ of an abelian category $ \ mathcal { a } $ is the endomorphism ring of the identity functor on that category. a localizing subcategory of a grothendieck category $ \ mathcal { c } $ is said to be stable if it is stable under essential extensions. the set $ \ mathbf { l } ^ { st } ( \ mathcal { c } ) $ of stable localizing subcategories of $ \ mathcal { c } $ is partially ordered under reverse inclusion. we show $ \ mathcal { l } \ mapsto z ( \ mathcal { c } / \ mathcal { l } ) $ defines a sheaf of commutative rings on $ \ mathbf { l } ^ { st } ( \ mathcal { c } ) $ with respect to finite coverings. when $ \ mathcal { c } $ is assumed to be locally noetherian, we also show that the sheaf condition holds for arbitrary coverings.
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arxiv:2210.12419
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in this report, we share our practical experience on crowdsourcing evaluation of research artifacts and reviewing of publications since 2008. we also briefly discuss encountered problems including reproducibility of experimental results and possible solutions.
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arxiv:1406.4020
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the ground - state properties of the two - dimensional hubbard model with nearest - neighbor and next - nearest - neighbor hoppings at half filling are studied by the path - integral - renormalization - group method. the nonmagnetic - insulator phase sandwiched by the the paramagnetic - metal phase and the antiferromagnetic - insulator phase shows evidence against translational symmetry breaking of the dimerized state, plaquette singlet state, staggered flux state, and charge ordered state. these results support that the genuine mott insulator which cannot be adiabatically continued to the band insulator is realized generically by umklapp scattering through the effects of geometrical frustration and quantum fluctuation in the two - dimensional system.
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arxiv:cond-mat/0207550
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in the last decade, white - light illuminated fabry - p \ ' erot interferometers wave been established as a widely used, relatively simple, reliable, and cost - effective way to precisely calibrate high - resolution echelle spectrographs. however, terrien et al. ( 2021 ) recently reported a chromatic drift of the fabry - p \ ' erot interferometer installed at the habitable - zone planet finder spectrograph. in particular, they found that the variation of the etalon effective gap size is not achromatic as usually assumed but in fact depends on wavelength. here, we present a similar study of the espresso fabry - p \ ' erot interferometer. using daily calibrations spanning a period of over 2. 5 years, we also find clear evidence for a chromatic drift with an amplitude of a few cm / s per day that has a characteristic, quasi - oscillatory dependence on wavelength. we conclude that this effect is probably caused by an aging of the dielectric mirror coatings and expect that similar chromatic drifts might affect all fabry - p \ ' erot interferometers used for calibration of astronomical spectrographs. however, we also demonstrate that the chromatic drift can be measured and in principle corrected using only standard calibrations based on hollow cathode lamp spectra.
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arxiv:2204.05713
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we present an alternative method for computing primary decomposition of zero - dimensional ideals over finite fields. based upon the further decomposition of the invariant subspace of the frobenius map acting on the quotient algebra in the algorithm given by s. gao, d. wan and m. wang in 2008, we get an alternative approach to compute all the primary components at once. as one example of our method, an improvement of berlekamp ' s algorithm by theoretical considerations which computes the factorization of univariate polynomials over finite fields is also obtained.
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arxiv:1112.6057
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an ewald decomposition of the two - dimensional yukawa potential and its derivative is presented for both the periodic and the free - space case. these modified bessel functions of the second kind of zeroth and first degrees are used e. g. when solving the modified helmholtz equation using a boundary integral method. the spectral ewald method is used to compute arising sums at o ( n log n ) cost for n source and target points. to facilitate parameter selection, truncation - error estimates are developed for both the real - space sum and the fourier - space sum, and are shown to estimate the errors well.
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arxiv:1911.04875
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the paper is concerned with the approximation of the deterministic the mean field type control system by a mean field markov chain. it turns out that the dynamics of the distribution in the approximating system is described by a system of ordinary differential equations. given a strategy for the markov chain, we explicitly construct a control in the deterministic mean field type control system. our method is a realization of the model predictive approach. the converse construction is also presented. these results lead to an estimate of the hausdorff distance between the bundles of motions in the deterministic mean field type control system and the mean field markov chain. especially, we pay the attention to the case when one can approximate the bundle of motions in the mean field type system by solutions of a finite systems of odes.
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arxiv:2308.02301
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this chapter provides a brief tutorial on some aspects of plasma physics that are fundamental to understanding the dynamics and energetics of the intracluster medium ( icm ). the tutorial is split into two parts : one that focuses on the thermal plasma component - - its stability, viscosity, conductivity, and ability to amplify magnetic fields to dynamical strengths via turbulence and other plasma processes ; and one that focuses on the non - thermal population of charged particles known as cosmic rays - - their acceleration, re - acceleration, and transport throughout the cluster volume. observational context is woven throughout the narrative, from constraints on the strength and geometry of intracluster magnetic fields and the effective viscosity of the icm, to examples of radio halos, radio relics, and cluster shocks that can test theories of particle acceleration. the promise of future x - ray missions to probe intracluster turbulence and discover the impact of small - scale plasma physics, coupled with sensitive, high - resolution radio observations of synchrotron - emitting plasma that reveal the properties of intracluster magnetic fields and particle - acceleration mechanisms, are likely to establish galaxy clusters as the premier cosmic laboratories for deciphering the fundamental physics of hot, dilute plasmas.
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arxiv:2205.02489
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the variety of sums of powers of a homogeneous polynomial of degree d in n variables is defined and investigated in some examples, old and new. these varieties are studied via apolarity and syzygies. classical results of sylvester ( 1851 ), hilbert ( 1888 ), dixon and stuart ( 1906 ) and some more recent results of mukai ( 1992 ) are presented together with new results for the cases ( n, d ) = ( 3, 8 ), ( 4, 2 ), ( 5, 3 ). in the last case the variety of sums of 8 powers of a general cubic form is a fano 5 - fold of index 1 and degree 660.
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arxiv:math/9801110
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the internal disorder of the two - dimensional confined hydrogenic atom is numerically studied in terms of the confinement radius for the 1 \ textit { s }, 2 \ textit { s }, 2 \ textit { p } and 3 \ textit { d } quantum states by means of the statistical cr \ ' amer - rao complexity measure. first, the confinement dependence of the variance and the fisher information of the position and momentum spreading of its electron distribution are computed and discussed. then, the cr \ ' amer - rao complexity measure ( which quantifies the combined balance of the charge concentration around the mean value and the gradient content of the electron distribution ) is investigated in position and momentum spaces. we found that confinement does distinguish complexity of the system for all quantum states by means of this two component measure.
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arxiv:2007.15913
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we provide an insight into the open data resources pertinent to the study of the spread of covid - 19 pandemic and its control. we identify the variables required to analyze fundamental aspects like seasonal behaviour, regional mortality rates, and effectiveness of government measures. open data resources, along with data - driven methodologies, provide many opportunities to improve the response of the different administrations to the virus. we describe the present limitations and difficulties encountered in most of the open - data resources. to facilitate the access to the main open - data portals and resources, we identify the most relevant institutions, at a world scale, providing covid - 19 information and / or auxiliary variables ( demographics, mobility, etc. ). we also describe several open resources to access covid - 19 data - sets at a country - wide level ( i. e. china, italy, spain, france, germany, u. s., etc. ). in an attempt to facilitate the rapid response to the study of the seasonal behaviour of covid - 19, we enumerate the main open resources in terms of weather and climate variables. conco - team : the authors of this paper belong to the control covid - 19 team, which is composed of different researches from universities of spain, italy, france, germany, united kingdom and argentina. the main goal of conco - team is to develop data - driven methods for the better understanding and control of the pandemic.
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arxiv:2004.06111
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characteristic temperatures in ferromagnetic - antiferromagnetic exchange biased systems are analyzed. in addition to usual blocking temperature of exchange bias $ t _ { b } $, and the n \ ' { e } el temperature of an antiferromagnet $ t _ { n } $, the inducing temperature $ t _ { ind } $, i. e., the temperature, at which the direction of exchange anisotropy is established, has been recently proposed. we demonstrate that this temperature is in general case different from $ t _ { b } $ and $ t _ { n } $. physics and experimental approaches to measure the inducing temperature are discussed. measurements of $ t _ { ind } $, in addition to $ t _ { b } $, and $ t _ { n } $, provide important information about exchange interactions in ferromagnetic - antiferromagnetic heterostructures.
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arxiv:cond-mat/0612500
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we present astra ( a } scene - aware transformer - based model for trajectory prediction ), a light - weight pedestrian trajectory forecasting model that integrates the scene context, spatial dynamics, social inter - agent interactions and temporal progressions for precise forecasting. we utilised a u - net - based feature extractor, via its latent vector representation, to capture scene representations and a graph - aware transformer encoder for capturing social interactions. these components are integrated to learn an agent - scene aware embedding, enabling the model to learn spatial dynamics and forecast the future trajectory of pedestrians. the model is designed to produce both deterministic and stochastic outcomes, with the stochastic predictions being generated by incorporating a conditional variational auto - encoder ( cvae ). astra also proposes a simple yet effective weighted penalty loss function, which helps to yield predictions that outperform a wide array of state - of - the - art deterministic and generative models. astra demonstrates an average improvement of 27 % / 10 % in deterministic / stochastic settings on the eth - ucy dataset, and 26 % improvement on the pie dataset, respectively, along with seven times fewer parameters than the existing state - of - the - art model ( see figure 1 ). additionally, the model ' s versatility allows it to generalize across different perspectives, such as bird ' s eye view ( bev ) and ego - vehicle view ( evv ).
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arxiv:2501.09878
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metasurfaces, with their ability to control electromagnetic waves, hold immense potential in optical device design, especially for applications requiring precise control over dispersion. this work introduces an approach to dispersion engineering using heterogeneous freeform metasurfaces, which overcomes the limitations of conventional metasurfaces that often suffer from poor transmission, narrow bandwidth, and restricted polarization responses. by transitioning from single - layer, canonical meta - atoms to bilayer architectures with non - intuitive geometries, our design decouples intrinsic material properties ( refractive index and group index ), enabling independent engineering of phase and group delays as well as higher - order dispersion properties, while achieving high - efficiency under arbitrary polarization states. we implement a two - stage multi - objective optimization process to generate libraries of meta - atoms, which are then utilized for the rapid design of dispersion - engineered metasurfaces. additionally, we present a bilayer metasurface stacking technique, paving the way for the realization of high - performance, dispersion - engineered optical devices. our approach is validated through the demonstration of metasurfaces exhibiting superior chromatic aberration correction and broadband performance, with over 81 % averaged efficiency across the 420 - nm visible - to - near - infrared bandwidth. our synergistic combination of advanced design physics, powerful freeform optimization methods, and bi - layer nanofabrication techniques represents a significant breakthrough compared to the state - of - the - art while opening new possibilities for broadband metasurface applications.
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arxiv:2412.12028
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given an annular link $ l $, there is a corresponding augmented link $ \ widetilde { l } $ in $ s ^ 3 $ obtained by adding a meridian unknot component to $ l $. in this paper, we construct a spectral sequence with the second page isomorphic to the annular khovanov homology of $ l $ and it converges to the reduced khovanov homology of $ \ widetilde { l } $. as an application, we classify all the links with the minimal rank of annular khovanov homology. we also give a proof that annular khovanov homology detects unlinks.
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arxiv:2109.02036
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the complex interplay of magnetohydrodynamics, gravity, and supersonic turbulence in the interstellar medium ( ism ) introduces non - gaussian structure that can complicate comparison between theory and observation. we show that the wavelet scattering transform ( wst ), in combination with linear discriminant analysis ( lda ), is sensitive to non - gaussian structure in 2d ism dust maps. wst - lda classifies magnetohydrodynamic ( mhd ) turbulence simulations with up to a 97 \ % true positive rate in our testbed of 8 simulations with varying sonic and alfv \ ' { e } nic mach numbers. we present a side - by - side comparison with two other methods for non - gaussian characterization, the reduced wavelet scattering transform ( rwst ) and the 3 - point correlation function ( 3pcf ). we also demonstrate the 3d - wst - lda and apply it to classification of density fields in position - position - velocity ( ppv ) space, where density correlations can be studied using velocity coherence as a proxy. wst - lda is robust to common observational artifacts, such as striping and missing data, while also sensitive enough to extract the net magnetic field direction for sub - alfv \ ' { e } nic turbulent density fields. we include a brief analysis of the effect of point spread functions and image pixelization on 2d - wst - lda applied to density fields, which informs the future goal of applying wst - lda to 2d or 3d all - sky dust maps to extract hydrodynamic parameters of interest.
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arxiv:2010.11963
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in mathematics, an inequality is a relation which makes a non - equal comparison between two numbers or other mathematical expressions. it is used most often to compare two numbers on the number line by their size. the main types of inequality are less than and greater than ( denoted by < and >, respectively the less - than and greater - than signs ). = = notation = = there are several different notations used to represent different kinds of inequalities : the notation a < b means that a is less than b. the notation a > b means that a is greater than b. in either case, a is not equal to b. these relations are known as strict inequalities, meaning that a is strictly less than or strictly greater than b. equality is excluded. in contrast to strict inequalities, there are two types of inequality relations that are not strict : the notation a ≤ b or a b or a b means that a is less than or equal to b ( or, equivalently, at most b, or not greater than b ). the notation a ≥ b or a b or a b means that a is greater than or equal to b ( or, equivalently, at least b, or not less than b ). in the 17th and 18th centuries, personal notations or typewriting signs were used to signal inequalities. for example, in 1670, john wallis used a single horizontal bar above rather than below the < and >. later in 1734, and, known as " less than ( greater - than ) over equal to " or " less than ( greater than ) or equal to with double horizontal bars ", first appeared in pierre bouguer ' s work. after that, mathematicians simplified bouguer ' s symbol to " less than ( greater than ) or equal to with one horizontal bar " ( ≤ ), or " less than ( greater than ) or slanted equal to " ( ). the relation not greater than can also be represented by a > b, { \ displaystyle a \ ngtr b, } the symbol for " greater than " bisected by a slash, " not ". the same is true for not less than, a < b. { \ displaystyle a \ nless b. } the notation a = b means that a is not equal to b ; this inequation sometimes is considered a form of strict inequality. it does not say that one is greater than the other ; it does not
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https://en.wikipedia.org/wiki/Inequality_(mathematics)
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the study comprehensively investigates the response of a combusting droplet during its interaction with high - speed transient flow imposed by a coaxially propagating blast wave. the blast wave is generated using a miniature shock generator which facilitates wide mach number range ( $ 1. 01 < m _ s < 1. 6 $ ). the interaction of the shock flow occurs in two stages : 1 ) interaction of the temporally decaying velocity ( $ \ rm v _ s $ ) imposed by blast wave and 2 ) interaction with the induced flow ( $ \ rm v _ { ind } $ ). the flame base lifts off due to the imposed flow, and the advection of flame base towards flame tip results in flame extinction for $ m _ s > 1. 06 $. the timescale of the flame extinction is faster ( interaction with $ \ rm v _ s $ ) for $ m _ s > 1. 1 $. the study investigates the effect on droplet regression, flame heat release rate and flame topological evolution during the interaction. the droplet regression rate gets enhanced after the interaction with blast wave for $ m _ s < 1. 06 $, while it slowed down due to complete extinction for $ m _ s > 1. 06 $. a momentary flame heat release rate ( hrr ) enhancement occurs during the interaction with shock flow, and this hrr enhancement is found to be more than 8 times the nominal unforced flame hrr for $ m _ s > 1. 1 $, where rapid flame extinction occurs due to faster interaction with $ \ rm v _ s $ ( $ \ sim o ( 10 ^ { - 1 } ) ms $ ). hrr enhancement has been attributed to the fuel vapor accumulation during the interaction. furthermore, for $ m _ s > 1. 1 $ ), compressible vortex interaction occurs with the droplet resulting in droplet atomization. the droplet shows a wide range of atomization response modes ranging for different shock strengths. no significant effect of nanoparticle ( np ) addition has been found on the flame dynamics due to the faster timescales. however, minimial effects of np addition are observed during droplet breakup due to fluid property variation.
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arxiv:2409.19329
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let $ \ omega \ subset \ mathbb { r } ^ { n + 1 } $, $ n \ geq 1 $, be an open and connected set. set $ \ mathcal { t } _ n $ to be the set of points $ \ xi \ in \ partial \ omega $ so that there exists an approximate tangent $ n $ - plane for $ \ partial \ omega $ at $ \ xi $ and $ \ partial \ omega $ satisfies the weak lower ahlfors - david $ n $ - regularity condition at $ \ xi $. we first show that $ \ mathcal { t } _ n $ can be covered by a countable union of boundaries of bounded lipschitz domains. then, letting $ \ partial ^ \ star \ omega $ be a subset of $ \ mathcal { t } _ n $ where $ \ omega $ satisfies an appropriate thickness condition, we prove that $ \ partial ^ \ star \ omega $ can be covered by a countable union of boundaries of bounded lipschitz domains contained in $ \ omega $. as a corollary we obtain that if $ \ omega $ has locally finite perimeter, $ \ partial \ omega $ is weakly lower ahlfors - david $ n $ - regular, and the measure - theoretic boundary coincides with the topological boundary of $ \ omega $ up to a set of $ \ mathcal { h } ^ n $ - measure zero, then $ \ partial \ omega $ can be covered, up to a set of $ \ mathcal { h } ^ n $ - measure zero, by a countable union of boundaries of bounded lipschitz domains that are contained in $ \ omega $. this implies that in such domains, $ \ mathcal { h } ^ n | _ { \ partial \ omega } $ is absolutely continuous with respect to harmonic measure.
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arxiv:1602.00677
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we analyse the results of our experimental laboratory approximation of motorways networks with slime mould physarum polycephalum. motorway networks of fourteen geographical areas are considered : australia, africa, belgium, brazil, canada, china, germany, iberia, italy, malaysia, mexico, the netherlands, uk, usa. for each geographical entity we represented major urban areas by oat flakes and inoculated the slime mould in a capital. after slime mould spanned all urban areas with a network of its protoplasmic tubes we extracted a generalised physarum graph from the network and compared the graphs with an abstract motorway graph using most common measures. the measures employed are the number of independent cycles, cohesion, shortest paths lengths, diameter, the harary index and the randic index. we obtained a series of intriguing results, and found that the slime mould approximates best of all the motorway graphs of belgium, canada and china, and that for all entities studied the best match between physarum and motorway graphs is detected by the randic index ( molecular branching index ).
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arxiv:1203.2851
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we investigate consequences of the discovery that fe ii emission in quasars, one of the spectroscopic signatures of " eigenvector 1 ", may originate in infalling clouds. eigenvector 1 correlates with the eddington ratio l / l _ edd so that fe ii / hbeta increases as l / l _ edd increases. we show that the " force multiplier ", the ratio of gas opacity to electron scattering opacity, is ~ 10 ^ 3 - 10 ^ 4 in fe ii - emitting gas. such gas would be accelerated away from the central object if the radiation force is able to act on the entire cloud. as had previously been deduced, infall requires that the clouds have large column densities so that a substantial amount of shielded gas is present. the critical column density required for infall to occur depends on l / l _ edd, establishing a link between eigenvector 1 and the fe ii / hbeta ratio. we see predominantly the shielded face of the infalling clouds rather than the symmetric distribution of emitters that has been assumed. the fe ii spectrum emitted by the shielded face is in good agreement with observations thus solving several long - standing mysteries in quasar emission lines.
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arxiv:0911.1173
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we have performed n - body simulations of tidally filling star clusters with a range of orbits in a milky way - like potential to study the effects of orbital inclination and eccentricity on their structure and evolution. at small galactocentric distances rgc, a non - zero inclination results in increased mass loss rates. tidal heating and disk shocking, the latter sometimes consisting of two shocking events as the cluster moves towards and away from the disk, help remove stars from the cluster. clusters with inclined orbits at large rgc have decreased mass loss rates than the non - inclined case, since the strength the disk potential decreases with rgc. clusters with inclined and eccentric orbits experience increased tidal heating due to a constantly changing potential, weaker disk shocks since passages occur at higher rgc, and an additional tidal shock at perigalacticon. the effects of orbital inclination decrease with orbital eccentricity, as a highly eccentric cluster spends the majority of its lifetime at a large rgc. the limiting radii of clusters with inclined orbits are best represented by the rt of the cluster when at its maximum height above the disk, where the cluster spends the majority of its lifetime and the rate of change in rt is a minimum. conversely, the effective radius is independent of inclination in all cases.
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arxiv:1409.0879
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recently, single - site observables have been shown to be useful for the detection of dynamical criticality due to an emergence of a universal critically - prethermal temporal regime in the magnetization [ arxiv : 2105. 05986 ]. here, we explore the potential of single - site observables as probes of quantum phase transitions in integrable and nonintegrable transverse - field ising chains ( tfic ). we analytically prove the requirement of zero modes for a quasi - stationary temporal regime to emerge at a bulk probe site, and show how this regime gives rise to a non - analytic behavior in the dynamical order profiles. our $ t $ - dmrg calculations verify the results of the quench mean - field theory for near - integrable tfic both with finite - size and finite - time scaling analyses. we find that both finite - size and finite - time analyses suggest a dynamical critical point for a strongly nonintegrable and locally connected tfic. we finally demonstrate the presence of a quasi - stationary regime in the power - law interacting tfic, and extract local dynamical order profiles for tfic in the long - range ising universality class with algebraic light cones.
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arxiv:2110.02995
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hd 169142 is part of the class of ( pre - ) transitional protoplanetary disks showing multiple carbon nanodust spectroscopic signatures ( aromatic, aliphatic ) dominating the infrared spectrum. precise constraints on the spatial distribution and properties of carbonaceous dust particles are essential to understanding the physics of the disk. the hd 169142 disk is seen almost face - on and thus offers a unique opportunity to study the dust radial evolution. we investigate the spatial distribution and properties of the carriers of several dust aromatic emission features in the disk across a broad spatial range ( 10 - 200 au ). we analysed imaging and spectroscopic observations in the 8 - 12 microns range from vlt / visir, as well as adaptive optics spectroscopic observations in the 3 - 4 microns range from vlt / naco. the data probes the spatial evolution of the 3. 3, 8. 6, and 11. 3 microns aromatic bands. to constrain the radial distribution of carbonaceous nano - grains, the observations were compared to models using the heterogeneous dust evolution model for interstellar solids ( themis ), integrated into the polaris radiative transfer code by calculating the thermal and stochastic heating of sub - micrometer dust grains. our data show predominant nano - particle emission at all radii ( resolution of about 0. 1 ", 12 au at 3 microns and 0. 3 ", 35 au at 10 microns ) in the hd 169142 disk. this unambiguously shows that carbonaceous nano - grains dominate radiatively the infrared spectrum in most of the disk, as suggested by previous studies. in order to account for both visir and naco emission maps, we show the need for aromatic particles distributed within the disk from the outermost regions to a radius of 20 au, corresponding to the outer limit of the inner cavity derived from previous observations. in the inner cavity, these aromatic particles might be present but their abundance would then be significantly decreased.
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arxiv:2205.00213
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