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graphs and recently hypergraphs have been known as an important tool for considering different properties of quantum many - body systems. in this paper, we study a mapping between an important class of quantum systems namely quantum calderbank - shor - steane ( css ) codes and ising - like systems by using hypergraphs. we show that the hamiltonian corresponding to a css code on a hypergraph $ h $ which is perturbed by a uniform magnetic field is mapped to hamiltonian of a ising - like system on dual hypergraph $ \ tilde { h } $ in a transverse field. interestingly, we show that a strong regime of couplings in one of the systems is mapped to a weak regime of couplings in another one. we also give some applications for such a mapping where we study robustness of different topological css codes against a uniform magnetic field including kitaev ' s toric codes defined on graphs and color codes in different dimensions. we show that a perturbed kitaev ' s toric code on an arbitrary graph is mapped to an ising model in a transverse field on the same graph and a perturbed color code on a d - colex is mapped to a ising - like model on a d - simplicial lattice in a transverse field. in particular, we use these results to explicitly compare the robustness of tc on different graphs in different dimensions. interestingly, our results show that the robustness of such topological codes defined on graphs decreases with increasing dimension. furthermore, we also use the duality mapping for some self - dual models where we exactly derive the point of phase transition. | arxiv:1710.02646 |
detection of moving objects is an essential capability in dealing with dynamic environments. most moving object detection algorithms have been designed for color images without depth. for robotic navigation where real - time rgb - d data is often readily available, utilization of the depth information would be beneficial for obstacle recognition. here, we propose a simple moving object detection algorithm that uses rgb - d images. the proposed algorithm does not require estimating a background model. instead, it uses an occlusion model which enables us to estimate the camera pose on a background confused with moving objects that dominate the scene. the proposed algorithm allows to separate the moving object detection and visual odometry ( vo ) so that an arbitrary robust vo method can be employed in a dynamic situation with a combination of moving object detection, whereas other vo algorithms for a dynamic environment are inseparable. in this paper, we use dense visual odometry ( dvo ) as a vo method with a bi - square regression weight. experimental results show the segmentation accuracy and the performance improvement of dvo in the situations. we validate our algorithm in public datasets and our dataset which also publicly accessible. | arxiv:2009.08746 |
we establish non - asymptotic lower bounds for the estimation of principal subspaces. as applications, we obtain new results for the excess risk of principal component analysis and the matrix denoising problem. | arxiv:2107.08723 |
we present a multi - instrument analysis of the rapidly oscillating ap ( roap ) star hd 42659. we have obtained $ b $ photometric data for this star and use these data, in conjunction with tess observations, to analyse the high - frequency pulsation in detail. we find a triplet which is split by the rotation frequency of the star ( $ \ nu _ { \ rm rot } = 0. 3756 $ d $ ^ { - 1 } $ ; $ p _ { \ rm rot } = 2. 66 $ d ) and present both distorted dipole and distorted quadrupole mode models. we show that the pulsation frequency, $ 150. 9898 $ d $ ^ { - 1 } $ ( $ p _ { \ rm puls } = 9. 54 $ min ) is greater than the acoustic cutoff frequency. we utilise 27 high - resolution ( $ r \ simeq65 \, 000 $ ), high signal - to - noise ( $ \ sim120 $ ) spectra to provide new orbital parameters for this, the only known roap star to be in a short period binary ( $ p _ { \ rm orb } = 93. 266 $ d ). we find the system to be more eccentric than previously thought, with $ e = 0. 317 $, and suggest the companion is a mid - f to early - k star. we find no significant trend in the average pulsation mode amplitude with time, as measured by tess, implying that the companion does not have an affect on the pulsation in this roap star. we suggest further photometric observations of this star, and further studies to find more roap stars in close binaries to characterise how binarity may affect the detection of roap pulsations. | arxiv:1908.10146 |
we present an overview of the sciver shared task, presented at the 2nd scholarly document processing ( sdp ) workshop at naacl 2021. in this shared task, systems were provided a scientific claim and a corpus of research abstracts, and asked to identify which articles support or refute the claim as well as provide evidentiary sentences justifying those labels. 11 teams made a total of 14 submissions to the shared task leaderboard, leading to an improvement of more than + 23 f1 on the primary task evaluation metric. in addition to surveying the participating systems, we provide several insights into modeling approaches to support continued progress and future research on the important and challenging task of scientific claim verification. | arxiv:2107.08188 |
in tandem with the recent advancements in foundation model research, there has been a surge of generative music ai applications within the past few years. as the idea of ai - generated or ai - augmented music becomes more mainstream, many researchers in the music ai community may be wondering what avenues of research are left. with regards to music generative models, we outline the current areas of research with significant room for exploration. firstly, we pose the question of foundational representation of these generative models and investigate approaches towards explainability. next, we discuss the current state of music datasets and their limitations. we then overview different generative models, forms of evaluating these models, and their computational constraints / limitations. subsequently, we highlight applications of these generative models towards extensions to multiple modalities and integration with artists ' workflow as well as music education systems. finally, we survey the potential copyright implications of generative music and discuss strategies for protecting the rights of musicians. while it is not meant to be exhaustive, our survey calls to attention a variety of research directions enabled by music foundation models. | arxiv:2409.09378 |
the recent discovery of high temperature superconductivity in a layered iron arsenide has led to an intensive search to optimize the superconducting properties of iron - based superconductors by changing the chemical composition of the spacer layer that is inserted between adjacent anionic iron arsenide layers. until now, superconductivity has only been found in compounds with a cationic spacer layer consisting of metal ions : li +, na +, k +, ba2 + or a pbo - type or perovskite - type oxide layer. electronic doping is usually necessary to control the fine balance between antiferromagnetism and superconductivity. superconductivity has also been reported in fese, which contains neutral layers similar in structure to those found in the iron arsenides but without the spacer layer. here we demonstrate the synthesis of lix ( nh2 ) y ( nh3 ) 1 - yfe2se2 ( x ~ 0. 6 ; y ~ 0. 2 ), with lithium ions, lithium amide and ammonia acting as the spacer layer, which exhibits superconductivity at 43 ( 1 ) k, higher than in any fese - derived compound reported so far and four times higher at ambient pressure than the transition temperature, tc, of the parent fe1. 01se. we have determined the crystal structure using neutron powder diffraction and used magnetometry and muon - spin rotation data to determine the superconducting properties. this new synthetic route opens up the possibility of further exploitation of related molecular intercalations in this and other systems in order to greatly optimize the superconducting properties in this family. | arxiv:1203.5046 |
the emergence of dipolar magnetic features on the solar surface is an idealization. most of the magnetic flux emergence occurs in complex multipolar regions. here, we show that the surface pattern of magnetic structures alone can reveal the sign of the underlying magnetic helicity in the nearly force - free coronal regions above. the sign of the magnetic helicity can be predicted to good accuracy by considering the three - dimensional position vectors of three spots on the sphere ordered by their relative strengths at the surface and compute from them the skew product. this product, which is a pseudoscalar, is shown to be a good proxy for the sign of the coronal magnetic helicity. | arxiv:1804.04160 |
in a supersymmetric extension of the standard model with local gauged baryon and lepton numbers ( blmssm ), there are new sources for lepton flavor violation, because the right - handed neutrinos, new gauginos and higgs are introduced. we investigate muon conversion to electron in nuclei within the blmssm in detail. the numerical results indicate that the $ \ mu \ rightarrow e $ conversion rates in nuclei within the blmssm can reach the experimental upper bound, which may be detected in the future experiments. | arxiv:1808.02597 |
in network function computation is as a means to reduce the required communication flow in terms of number of bits transmitted per source symbol. however, the rate region for the function computation problem in general topologies is an open problem, and has only been considered under certain restrictive assumptions ( e. g. tree networks, linear functions, etc. ). in this paper, we propose a new perspective for distributing computation, and formulate a flow - based delay cost minimization problem that jointly captures the costs of communications and computation. we introduce the notion of entropic surjectivity as a measure to determine how sparse the function is and to understand the limits of computation. exploiting little ' s law for stationary systems, we provide a connection between this new notion and the computation processing factor that reflects the proportion of flow that requires communications. this connection gives us an understanding of how much a node ( in isolation ) should compute to communicate the desired function within the network without putting any assumptions on the topology. our analysis characterizes the functions only via their entropic surjectivity, and provides insight into how to distribute computation. we numerically test our technique for search, mapreduce, and classification tasks, and infer for each task how sensitive the processing factor to the entropic surjectivity is. | arxiv:1912.03531 |
we argue that the degrees of freedom in a d - dimensional cft can be re - organized in an insightful way by studying observables on the moduli space of causal diamonds ( or equivalently, the space of pairs of timelike separated points ). this 2d - dimensional space naturally captures some of the fundamental nonlocality and causal structure inherent in the entanglement of cft states. for any primary cft operator, we construct an observable on this space, which is defined by smearing the associated one - point function over causal diamonds. known examples of such quantities are the entanglement entropy of vacuum excitations and its higher spin generalizations. we show that in holographic cfts, these observables are given by suitably defined integrals of dual bulk fields over the corresponding ryu - takayanagi minimal surfaces. furthermore, we explain connections to the operator product expansion and the first law of entanglement entropy from this unifying point of view. we demonstrate that for small perturbations of the vacuum, our observables obey linear two - derivative equations of motion on the space of causal diamonds. in two dimensions, the latter is given by a product of two copies of a two - dimensional de sitter space. for a class of universal states, we show that the entanglement entropy and its spin - three generalization obey nonlinear equations of motion with local interactions on this moduli space, which can be identified with liouville and toda equations, respectively. this suggests the possibility of extending the definition of our new observables beyond the linear level more generally and in such a way that they give rise to new dynamically interacting theories on the moduli space of causal diamonds. various challenges one has to face in order to implement this idea are discussed. | arxiv:1606.03307 |
group iv and v monolayers are the promising state - of - the - art 2d materials owing to their high carrier mobility, tunable bandgaps, and optical linear dichroism along with outstanding electronic and thermoelectric properties. furthermore, recent studies reveal the stability of free - standing 2d monolayers by hydrogenation. inspired by this, we systematically predict and investigate the structure and properties of various hydrogen saturated silicon phosphide ( h - si - p ) monolayers, based on first - principles calculations. according to the results, h - si - p monolayers belong to indirect bandgap semiconductors with a highly stable structure. their bandgaps and band edge positions assessed using accurate hybrid functional are shown to be effectively adjusted by applying a biaxial strain. furthermore, the absorption spectra of these monolayers, simulated in the context of time - dependent density functional theory, exhibit their excellent potential for solar energy conversion and visible - light - driven photocatalytic water splitting. in this respect, this work provides valuable guidance for finding more 2d semiconductors and nanostructures for nanoelectronic and optoelectronic applications, as well as for photocatalytic water splitting. | arxiv:2101.05437 |
in this paper we study the ( 2, k ) - generation of the finite classical groups sl ( 4, q ), sp ( 4, q ), su ( 4, q ^ 2 ) and their projective images. here k is the order of an arbitrary element of sl ( 2, q ), subject to the necessary condition k > = 3. when q is even we allow also k = 4. | arxiv:1101.2358 |
understanding the formation of the first stars and galaxies is a key problem in modern cosmology. in these lecture notes, we will derive some of the basic physical principles underlying this emerging field. we will consider the basic cosmological context, the cooling and chemistry in primordial gas, the physics of gravitational instability, and the main properties of the first stars. we will conclude with a discussion of the observational signature of the first sources of light, to be probed with future telescopes, such as the james webb space telescope. | arxiv:1203.3824 |
the space - time monopole equation on $ \ r ^ { 2 + 1 } $ can be derived by a dimensional reduction of the anti - self - dual yang mills equations on $ \ r ^ { 2 + 2 } $. it can be also viewed as the hyperbolic analog of bogomolny equations. we uncover null forms in the nonlinearities and employ optimal bilinear estimates in the framework of wave - sobolev spaces. as a result, we show the equation is locally wellposed in the coulomb gauge for initial data sufficiently small in $ h ^ s $ for $ s > { 1 / 4 } $. | arxiv:0712.1393 |
we study the influence of the coulomb force on the fermi beta - decays in nuclei. this work is composed of two main parts. in the first part, we calculate the coulomb corrections to super - allowed beta decay. we use the notion of the isovector monopole state and the self - consistent charge - exchange random phase approximation to compute the correction. in the second part of this work, we examine the influence of the anti - analog state on isospin mixing in the isobaric analog state and the correction to the beta - decay fermi transition. | arxiv:2101.06199 |
in this paper, a novel framework that uses wireless mobile miners ( mms ) for computation purposes in a blockchain system is proposed. in the introduced system, the blockchain ledger is located at the communication nodes ( cns ), and the mms associated with cns process the blockchain ' s proof - of - work ( pow ) computation to verify the originality of the data. the mm that is the first to finish its pow will receive a reward by sending its computing result to the cns that are connected to other mms. in the considered scenario, a blockchain forking event occurs if the mm having the shortest pow delay fails to be the first to update its computing result to other mms. to enable such mobile operations for a blockchain with minimum forking events, it is imperative to maintain low - latency wireless communications between mms and cns. to analyze the sensitivity of the system to latency, the probability of occurrence of a forking event is theoretically derived. the system is then designed so as to compute the forked block ' s pow again to recover from a forking event. for this case, the average energy consumption of an mm is derived as a function of the system parameters such as the number of mms and power consumed by the computing, transmission, and mobility processes of the mms. simulation results verify the analytical derivations and show that using a larger number of mms can reduce the energy consumption by up to 94. 5 % compared to a blockchain system with a single mm. | arxiv:1906.06759 |
let $ n $ be a closed, connected, and oriented riemannian manifold, which admits a quasiregular $ \ omega $ - curve $ \ mathbb { r } ^ n \ to n $ with infinite energy. we prove that, if the de rham class of $ \ omega $ is non - zero and belongs to a so - called k \ " unneth ideal, then there exists a non - trivial graded algebra homomorphism $ h _ { \ mathrm { dr } } ^ * ( n ) \ to \ bigwedge ^ * \ mathbb { r } ^ n $ from the de rham algebra $ h _ { \ mathrm { dr } } ^ * ( n ) $ of $ n $ to the exterior algebra $ \ bigwedge ^ * \ mathbb { r } ^ n $. as an application, we give examples of pairs $ ( n, \ omega ) $, where $ n $ is a closed manifold and $ \ omega $ is a closed $ n $ - form for $ n < \ dim n $, for which every quasiregular $ \ omega $ - curve $ \ mathbb { r } ^ n \ to n $ is constant. | arxiv:2312.04347 |
the ability to incrementally learn new classes is vital to all real - world artificial intelligence systems. a large portion of high - impact applications like social media, recommendation systems, e - commerce platforms, etc. can be represented by graph models. in this paper, we investigate the challenging yet practical problem, graph few - shot class - incremental ( graph fcl ) problem, where the graph model is tasked to classify both newly encountered classes and previously learned classes. towards that purpose, we put forward a graph pseudo incremental learning paradigm by sampling tasks recurrently from the base classes, so as to produce an arbitrary number of training episodes for our model to practice the incremental learning skill. furthermore, we design a hierarchical - attention - based graph meta - learning framework, hag - meta. we present a task - sensitive regularizer calculated from task - level attention and node class prototypes to mitigate overfitting onto either novel or base classes. to employ the topological knowledge, we add a node - level attention module to adjust the prototype representation. our model not only achieves greater stability of old knowledge consolidation, but also acquires advantageous adaptability to new knowledge with very limited data samples. extensive experiments on three real - world datasets, including amazon - clothing, reddit, and dblp, show that our framework demonstrates remarkable advantages in comparison with the baseline and other related state - of - the - art methods. | arxiv:2112.12819 |
major depressive disorder ( mdd ) is a prevalent psychiatric disorder that is associated with significant healthcare burden worldwide. phenotyping of mdd can help early diagnosis and consequently may have significant advantages in patient management. in prior research mdd phenotypes have been extracted from structured electronic health records ( ehr ) or using electroencephalographic ( eeg ) data with traditional machine learning models to predict mdd phenotypes. however, mdd phenotypic information is also documented in free - text ehr data, such as clinical notes. while clinical notes may provide more accurate phenotyping information, natural language processing ( nlp ) algorithms must be developed to abstract such information. recent advancements in nlp resulted in state - of - the - art neural language models, such as bidirectional encoder representations for transformers ( bert ) model, which is a transformer - based model that can be pre - trained from a corpus of unsupervised text data and then fine - tuned on specific tasks. however, such neural language models have been underutilized in clinical nlp tasks due to the lack of large training datasets. in the literature, researchers have utilized the distant supervision paradigm to train machine learning models on clinical text classification tasks to mitigate the issue of lacking annotated training data. it is still unknown whether the paradigm is effective for neural language models. in this paper, we propose to leverage the neural language models in a distant supervision paradigm to identify mdd phenotypes from clinical notes. the experimental results indicate that our proposed approach is effective in identifying mdd phenotypes and that the bio - clinical bert, a specific bert model for clinical data, achieved the best performance in comparison with conventional machine learning models. | arxiv:2104.09644 |
we derive inner dark matter halo density profile slopes for a sample of 200 dwarf galaxies by inverting rotation curves obtained from high - quality, long - slit optical spectra. using simulations to assess the impact of long - slit observing and data processing errors on our measurements, we conclude that our observations are consistent with the cuspy halos predicted by the cdm paradigm. | arxiv:astro-ph/0310528 |
the study was conducted to develop an appropriate model that could predict the weekly reported malaria incidence in the philippines using the box - jenkins method. the data were retrieved from the department of health ( doh ) website in the philippines. it contains 70 data points of which 60 data points were used in model building and the remaining 10 data points were used for forecast evaluation. the r statistical software was used to do all the necessary computations in the study. box - cox transformation and differencing was done to make the series stationary. based on the results of the analysis, arima ( 2, 1, 0 ) is the appropriate model for the weekly malaria incidence in the philippines. | arxiv:1902.07953 |
we investigate the difficulties that students in calculus - based introductory physics courses have with the concepts of symmetry, electric field, and electric flux which are important for applying gauss ' s law. the determination of the electric field using gauss ' s law requires determining the symmetry of a particular charge distribution and predicting the direction of the electric field everywhere if a high symmetry exists. effective application of gauss ' s law implicitly requires understanding the principle of superposition for electric fields. helping students learn when gauss ' s law can be readily applied to determine the strength of the electric field, and then helping them learn to determine the appropriate shape of gaussian surfaces if sufficient symmetry exists, can help develop their reasoning and problem - solving skills. we administered free - response and multiple - choice questions and conducted interviews with individual students using a think - aloud protocol to elucidate the difficulties that students have with the concepts of symmetry, electric field, and electric flux. we also developed a multiple - choice test that targets these conceptual issues to obtain quantitative information about their difficulties and administered it to 541 students in the introductory calculus - based physics courses and to upper - level undergraduates in an electricity and magnetism course and to graduate students enrolled in a ta seminar course. we find that undergraduate students have many common difficulties with these concepts. | arxiv:1602.07376 |
a hadamard matrix is a scaled orthogonal matrix with $ \ pm 1 $ entries. such matrices exist in certain dimensions : the hadamard conjecture is that such a matrix always exists when $ n $ is a multiple of 4. a conjecture attributed to ryser is that no circulant hadamard matrices exist when $ n > 4 $. recently, dong and rudelson proved the existence of approximate hadamard matrices in all dimensions : there exist universal $ 0 < c < c < \ infty $ so that for all $ n \ geq 1 $, there is a matrix $ a \ in \ left \ { - 1, 1 \ right \ } ^ { n \ times n } $ satisfying, for all $ x \ in \ mathbb { r } ^ n $, $ $ c \ sqrt { n } \ | x \ | _ 2 \ leq \ | ax \ | _ 2 \ leq c \ sqrt { n } \ | x \ | _ 2. $ $ we observe that, as a consequence of the existence of flat littlewood polynomials, circulant approximate hadamard matrices exist for all $ n \ geq 1 $. | arxiv:2402.13202 |
the potential of the surface brightness fluctuations ( sbf ) method to determine the membership of dwarf elliptical galaxies ( des ) in nearby galaxy clusters is investigated. extensive simulations for sbf measurements on des in the i - band for various combinations of distance modulus, seeing and integration time are presented, based on average vlt fors1 and fors2 zero points. these show that for distances up to 20 mpc ( fornax or virgo cluster distance ), reliable membership determination of des can be obtained down to very faint magnitudes - 10 < m _ v < - 12 mag ( 25 mag / arcsec ^ 2 ) within integration times of the order of 1 hour and with good seeing. comparing the limiting magnitudes of the method for the different simulated observing conditions we derive some simple rules to calculate integration time and seeing needed to reach a determined limiting magnitude at a given distance modulus for observing conditions different to the ones adopted in the simulations. our simulations show a small offset of the order of 0. 15 mag towards measuring too faint sbf. it is shown that this is due to loss of fluctuation signal when recovering pixel - to - pixel fluctuations from a seeing convolved image. to check whether our simulations represent well the behaviour of real data, sbf measurements for a real and simulated sample of bright centaurus cluster des are presented. they show that our simulations are in good agreement with the achievable s / n of sbf measurements on real galaxies. | arxiv:astro-ph/0303577 |
we discuss the linearization of einstein equations in the presence of a cosmological constant, by expanding the solution for the metric around a flat minkowski space - time. we demonstrate that one can find consistent solutions to the linearized set of equations for the metric perturbations, in the lorentz gauge, which are not spherically symmetric, but they rather exhibit a cylindrical symmetry. we find that the components of the gravitational field satisfying the appropriate poisson equations have the property of ensuring that a scalar potential can be constructed, in which both contributions, from ordinary matter and $ \ lambda > 0 $, are attractive. in addition, there is a novel tensor potential, induced by the pressure density, in which the effect of the cosmological constant is repulsive. we also linearize the schwarzschild - de sitter exact solution of einstein ' s equations ( due to a generalization of birkhoff ' s theorem ) in the domain between the two horizons. we manage to transform it first to a gauge in which the 3 - space metric is conformally flat and, then, make an additional coordinate transformation leading to the lorentz gauge conditions. we compare our non - spherically symmetric solution with the linearized schwarzschild - de sitter metric, when the latter is transformed to the lorentz gauge, and we find agreement. the resulting metric, however, does not acquire a proper newtonian form in terms of the unique scalar potential that solves the corresponding poisson equation. nevertheless, our solution is stable, in the sense that the physical energy density is positive. | arxiv:0910.3637 |
a random surface scattering in a one - mode waveguide is studied in the case when the surface profile has long - range correlations along the waveguide. analytical treatment of this problem shows that with a proper choice of the surface, one can arrange any desired combination of transparent and non - transparent frequency windows. we suggest a method to find such profiles, and demonstrate its effectiveness by making use of direct numerical simulations. | arxiv:cond-mat/0105498 |
the semi - tensor product ( stp ) of matrices which was proposed by daizhan cheng in 2001 [ 2 ], is a natural generalization of the standard matrix product and well defined at every two finite - dimensional matrices. in 2016, cheng proposed a new concept of semi - tensor addition ( sta ) which is a natural generalization of the standard matrix addition and well defined at every two finite - dimensional matrices with the same ratio between the numbers of rows and columns [ 1 ]. in addition, an identify equivalence relation between matrices was defined in [ 1 ], stp and sta were proved valid for the corresponding identify equivalence classes, and the corresponding quotient space was endowed with an algebraic structure and a manifold structure. in this follow - up paper, we give a new concise basis for the quotient space, which also shows that the lie algebra corresponding to the quotient space is of countably infinite dimension. | arxiv:1608.01578 |
we prove that any commutative group scheme separated over a noetherian normal scheme admits a canonical structure of a presheaf with transfers, which is characterized by a simple condition on radicial transfers. | arxiv:2112.09846 |
we prove the relative index conjecture, which in turn implies that the set of embeddable deformations of a strictly pseudoconvex cr - structure on a compact 3 - manifold is closed in the c \ infty - topology. | arxiv:1203.5456 |
model selection is a major challenge in non - parametric clustering. there is no universally admitted way to evaluate clustering results for the obvious reason that no ground truth is available. the difficulty to find a universal evaluation criterion is a consequence of the ill - defined objective of clustering. in this perspective, clustering stability has emerged as a natural and model - agnostic principle : an algorithm should find stable structures in the data. if data sets are repeatedly sampled from the same underlying distribution, an algorithm should find similar partitions. however, stability alone is not well - suited to determine the number of clusters. for instance, it is unable to detect if the number of clusters is too small. we propose a new principle : a good clustering should be stable, and within each cluster, there should exist no stable partition. this principle leads to a novel clustering validation criterion based on between - cluster and within - cluster stability, overcoming limitations of previous stability - based methods. we empirically demonstrate the effectiveness of our criterion to select the number of clusters and compare it with existing methods. code is available at https : / / github. com / florentf9 / skstab. | arxiv:2006.08530 |
explainability and uncertainty quantification are key to trustable artificial intelligence. however, the reasoning behind uncertainty estimates is generally left unexplained. identifying the drivers of uncertainty complements explanations of point predictions in recognizing model limitations and enhancing transparent decision - making. so far, explanations of uncertainties have been rarely studied. the few exceptions rely on bayesian neural networks or technically intricate approaches, such as auxiliary generative models, thereby hindering their broad adoption. we propose a straightforward approach to explain predictive aleatoric uncertainties. we estimate uncertainty in regression as predictive variance by adapting a neural network with a gaussian output distribution. subsequently, we apply out - of - the - box explainers to the model ' s variance output. this approach can explain uncertainty influences more reliably than complex published approaches, which we demonstrate in a synthetic setting with a known data - generating process. we substantiate our findings with a nuanced, quantitative benchmark including synthetic and real, tabular and image datasets. for this, we adapt metrics from conventional xai research to uncertainty explanations. overall, the proposed method explains uncertainty estimates with little modifications to the model architecture and outperforms more intricate methods in most settings. | arxiv:2312.07252 |
the effective receptive field ( erf ) plays an important role in transform coding, which determines how much redundancy can be removed during transform and how many spatial priors can be utilized to synthesize textures during inverse transform. existing methods rely on stacks of small kernels, whose erfs remain insufficiently large, or heavy non - local attention mechanisms, which limit the potential of high - resolution image coding. to tackle this issue, we propose large receptive field transform coding with adaptive weights for learned image compression ( llic ). specifically, for the first time in the learned image compression community, we introduce a few large kernelbased depth - wise convolutions to reduce more redundancy while maintaining modest complexity. due to the wide range of image diversity, we further propose a mechanism to augment convolution adaptability through the self - conditioned generation of weights. the large kernels cooperate with non - linear embedding and gate mechanisms for better expressiveness and lighter pointwise interactions. our investigation extends to refined training methods that unlock the full potential of these large kernels. moreover, to promote more dynamic inter - channel interactions, we introduce an adaptive channel - wise bit allocation strategy that autonomously generates channel importance factors in a self - conditioned manner. to demonstrate the effectiveness of the proposed transform coding, we align the entropy model to compare with existing transform methods and obtain models llic - stf, llic - elic, and llic - tcm. extensive experiments demonstrate that our proposed llic models have significant improvements over the corresponding baselines and reduce the bd - rate by 9. 49 %, 9. 47 %, 10. 94 % on kodak over vtm - 17. 0 intra, respectively. our llic models achieve state - of - the - art performances and better trade - offs between performance and complexity. | arxiv:2304.09571 |
for face - centered cubic ( fcc ) and tetragonal ( fct ) iron a large number of magnetic configurations as a function of crystal structural parameters were studied by means of density functional theory. the stability of magnetic structures was defined by the magnetic re - orientation energy $ \ delta { e } ^ i _ \ text { reor } $ as the difference of the total energy of configuration $ i $ and that of the fcc ferromagnetic state. the cluster expansion technique was applied to several volumes deriving $ \ delta { e } _ \ text { reor } $ for more than 90. 000 collinear spin structures for each volume. a variety of structures with promisingly low $ \ delta { e } _ \ text { reor } $ were tetragonally distorted according to a two - dimensional mesh defined by volume per atom and $ c / a $ ratio of the distortion. at each of the points on this mesh $ \ delta e _ \ text { reor } $ of all collinear structure were compared to results for non - collinear spin spirals ( ss ) which were calculated for a grid of propagation directions. the lowest $ \ delta { e } _ \ text { reor } $ of all investigated spin structures then defined the magnetic structure map spanned by volume per atom and $ c / a $ ratio. three local minima were identified and for each of the minima ss were calculated on a fine grid of propagation vectors. for the volume per atom of 10. 6 \ aa $ ^ 3 $ and the distortion range $ 0. 94 \ le c / a \ le 1. 01 $ we found a new, surprisingly simple collinear spin structure with four atoms per fct unit cell to be the most stable one. this structure was called afm / nm because it consists of two atoms with anti - ferromagnetically ordered local moments of $ \ pm 1. 8 \ mu _ \ text { b } $ and of two nonmagnetic atoms with zero local moment. it seems that the newly detected afm / nm structure explains a variety of puzzling experimental results. | arxiv:1312.4313 |
we compare observed clustering of quasars and galaxies as a function of redshift, mass, luminosity, & color / morphology, to constrain models of quasar fueling and spheroid - bh co - evolution. high redshift quasars are shown to be drawn from progenitors of local early - type galaxies, with the characteristic quasar luminosity l * reflecting a characteristic mass of ' active ' bh / host populations at each redshift. evolving observed high - z quasar clustering to z = 0 predicts a trend of clustering in ' quasar remnants ' as a function of stellar mass identical to that observed for early - types. however, quasar clustering does not simply reflect observed early ( or late ) - type populations ; at each redshift, quasars cluster as an ' intermediate ' population. comparing with the age of elliptical stellar populations reveals that this ' intermediate ' population represents those ellipticals undergoing or terminating their final significant star formation at each epoch. assuming that quasar triggering is associated with the formation / termination epoch of ellipticals predicts quasar clustering at all observed redshifts without any model dependence or assumptions about quasar light curves, lifetimes, or accretion rates. this is not true for disks or quasar halos : i. e. quasars do not generically trace star formation, disks, or halo assembly. quasar clustering at all z is consistent with a constant halo mass ~ 4x10 ^ { 12 } m _ sun, similar to local ' group scales. ' the observations support a scenario in which major mergers trigger quasar activity and dominate bright, high - z quasar populations. we show that measurements of quasar clustering versus luminosity at z ~ 1 can be used to constrain different lower - luminosity agn fueling mechanisms, and that high - z clustering is sensitive to whether or not systems ' shut down ' growth at z > 3. | arxiv:astro-ph/0611792 |
we characterize spin wave propagation and its modification by an electrical current in permalloy ( py ) / pt bilayers with py thickness between 4 and 20 nm. first, we analyze the frequency non - reciprocity of surface spin waves and extract from it the interfacial dzyaloshinskii - moriya interaction constant $ d _ s $ accounting for an additional contribution due to asymmetric surface anisotropies. second, we measure the spin - wave relaxation rate and deduce from it the py / pt spin mixing conductance $ g ^ { \ uparrow \ downarrow } _ { eff } $. last, applying a \ textit { dc } electrical current, we extract the spin hall conductivity $ \ sigma _ { sh } $ from the change of spin wave relaxation rate due to the spin - hall spin transfer torque. we obtain a consistent picture of the spin wave propagation data for different film thicknesses using a single set of parameters $ d _ s = 0. 25 $ pj / m, $ g ^ { \ uparrow \ downarrow } _ { eff } = 3. 2 \ times 10 ^ { 19 } $ m $ ^ { - 2 } $ and $ \ sigma _ { sh } = 4 \ times10 ^ { 5 } $ s / m. | arxiv:1909.04935 |
we extend wilkes ' results on the profinite rigidity of sfss to the setting of central extensions of 2 - orbifold groups with higher - rank centre. we prove that both rigid and non - rigid phenomena arise in this setting and that the non - rigid phenomena are transient in the sense that if $ \ widehat { g } _ 1 \ cong \ widehat { g } _ 2 $, then $ g _ 1 \ times \ mathbb { z } \ cong g _ 2 \ times \ mathbb { z } $. | arxiv:2304.01105 |
in materials and pharmaceutical development, rapidly and accurately determining the similarity between x - ray powder diffraction ( xrpd ) measurements is crucial for efficient solid form screening and analysis. we present smolnet, a classifier based on a siamese network architecture, designed to automate the comparison of xrpd patterns. our results show that training smolnet on loss functions from the self - supervised learning domain yields a substantial boost in performance with respect to class separability and precision, specifically when classifying phases of previously unseen compounds. the application of smolnet demonstrates significant improvements in screening efficiency across multiple active pharmaceutical ingredients, providing a powerful tool for scientists to discover and categorize measurements with reliable accuracy. | arxiv:2411.03308 |
we compute the four - fermi neutralino - quark interaction lagrangian including contributions from the cp violating phases in the mssm. we find that neutralino - nucleus scattering cross - sections relevant for direct detection experiments show a strong dependence on the value of the cp - violating phase associated with the $ \ mu $ parameter, $ \ theta _ \ mu $. in some cases, for a broad range of non - zero $ \ theta _ \ mu $, there are cancellations in the cross - sections which reduce the cross - section by more than an order of magnitude. in other cases, there may be enhancements as one varies $ \ theta _ \ mu $. | arxiv:hep-ph/9806413 |
dynamical correlation functions of the toric code in a uniform magnetic field are studied inside the topological phase, in the small - field limit. such an experimentally measurable quantity displays rich field - dependent features that can be understood via the interplay of the kinetics and the interaction of the anyonic excitations. in particular, it is sensitive to the two - quasiparticle bound states that are present in the spectrum for a wide range of magnetic fields. interestingly, such collective modes can even constitute the lowest - energy excitations of the system. | arxiv:1308.6150 |
typical studies of quantum error correction assume probabilistic pauli noise, largely because it is relatively easy to analyze and simulate. consequently, the effective logical noise due to physically realistic coherent errors is relatively unknown. here, we prove that encoding a system in a stabilizer code and measuring error syndromes decoheres errors, that is, causes coherent errors to converge toward probabilistic pauli errors, even when no recovery operations are applied. two practical consequences are that the error rate in a logical circuit is well quantified by the average gate fidelity at the logical level and that essentially optimal recovery operators can be determined by independently optimizing the logical fidelity of the effective noise per syndrome. | arxiv:1805.08802 |
a phase plot of the oil economy is built using the literature data of world oil production, price, and eroei ( energy returned on energy invested ). an analogy between the oil economy and the benard convection is proposed ; some methods of interpretation and forecast of the system behavior are also shown based on " phase portrait " using as main variables the price, production and eroei values. a scenery is proposed on this basis. | arxiv:1708.03533 |
we report negative capacitance at low frequencies in organic semiconductor based diodes and show that it appears only under bipolar injection conditions. we account quantitatively for this phenomenon by the recombination current due to electron - hole annihilation. simple addition of the recombination current to the well established model of space charge limited current in the presence of traps, yields excellent fits to the experimentally measured admittance data. the dependence of the extracted characteristic recombination time on the bias voltage is indicative of a recombination process which is mediated by localized traps. | arxiv:0706.3933 |
agf2 is a layered material and a correlated charge transfer insulator with an electronic structure very similar to the parent compounds of cuprate high - tc superconductors. it is also interesting for being a powerful oxidizer. here we present a first principles computation of its electronic properties in a slab geometry including its work function for the ( 010 ) surface ( 7. 76 ev ) which appears to be one of the highest among known materials surpassing even that of fluorinated diamond ( 7. 24 ev ). we demonstrate that agf2 will show a broken - gap type alignment becoming electron doped and promoting injection of holes in many wide band gap insulators if chemical reaction can be avoided. novel junction devices involving p type and n type superconductors are proposed. the issue of chemical reaction is discussed in connection with the possibility to create flat agf2 monolayers achieving high - tc superconductivity. as a first step in this direction, we study the stability and properties of an isolated agf2 monolayer. | arxiv:2006.05695 |
we study the target control of asynchronous boolean networks, to identify efficacious interventions that can drive the dynamics of a given boolean network from any initial state to the desired target attractor. based on the application time, the control can be realised with three types of perturbations, including instantaneous, temporary and permanent perturbations. we develop efficient methods to compute the target control for a given target attractor with three types of perturbations. we compare our methods with the stable motif - based control on a variety of real - life biological networks to evaluate their performance. we show that our methods scale well for large boolean networks and they are able to identify a rich set of solutions with a small number of perturbations. | arxiv:2101.00644 |
precision matrix, which is the inverse of covariance matrix, plays an important role in statistics, as it captures the partial correlation between variables. testing the equality of two precision matrices in high dimensional setting is a very challenging but meaningful problem, especially in the differential network modelling. to our best knowledge, existing test is only powerful for sparse alternative patterns where two precision matrices differ in a small number of elements. in this paper we propose a data - adaptive test which is powerful against either dense or sparse alternatives. multiplier bootstrap approach is utilized to approximate the limiting distribution of the test statistic. theoretical properties including asymptotic size and power of the test are investigated. simulation study verifies that the data - adaptive test performs well under various alternative scenarios. the practical usefulness of the test is illustrated by applying it to a gene expression data set associated with lung cancer. | arxiv:1810.08880 |
we investigate the correlations between spectral index, jet side and extent of the radio lobes for a sample of nearby frii radio galaxies. in dennett - thorpe et al. ( 1997 ) we studied a sample of quasars and found that the high surface brightness regions had flatter spectra on the jet side ( explicable as a result of doppler beaming ) whilst the extended regions had spectral asymmetries dependent on lobe length. unified schemes predict that asymmetries due to beaming will be much smaller in narrow - line radio galaxies than in quasars : we therefore investigate in a similar manner, a sample of radio galaxies with detected jets. we find that spectral asymmetries in these objects are uncorrelated with jet sidedness at all brightness levels, but depend on relative lobe volume. our results are not in conflict with unified schemes, but suggest that the differences between the two samples are due primarily to power or redshift, rather than to orientation. we also show directly that hotspot spectra steepen as a function of radio power or redshift. whilst a shift in observed frequency due to the redshift may account for some of the steepening, it cannot account for all of it, and a dependence on radio power is required. | arxiv:astro-ph/9811075 |
integration of smart grid technologies in distribution systems, particularly behind - the - meter initiatives, has a direct impact on transmission network planning. this paper develops a coordinated expansion planning of transmission and active distribution systems via a stochastic multistage mathematical programming model. in the transmission level, in addition to lines, sitting and sizing of utility - scale battery energy storage systems and wind power plants under renewable portfolio standard policy are planned. switchable feeders and distributed generations are decision variables in the distribution level while the impact of demand response programs as a sort of behind - the - meter technologies is accommodated as well. expansion of electric vehicle taxi charging stations is included as a feasible option in both transmission and distribution levels. in order to deal with short - term uncertainty of load demand, renewable energy sources output power, and the charging pattern of electric vehicle taxis in each station, a chronological time - period clustering algorithm along with monte carlo simulation is utilized. the proposed model is tackled by means of benders dual decomposition ( bdd ) method. the ieee rts test system ( as the transmission system ) along with four ieee 33 - node test feeders ( as distribution test systems ) are examined to validate effectiveness of the proposed model. | arxiv:2310.05776 |
we reanalyse $ \ bar p p $ and $ pp $ high energy data of the elastic scattering above $ \ sqrt { s } = 5 $ gev on the total cross - section $ \ sigma _ { tot } $ and on the forward $ \ rho $ - ratio for various models of pomeron, utilizing two methods. the first one is based on analytic amplitudes, the other one relies on assumptions for $ \ sigma _ { tot } $ and on dispersion relation for $ \ rho $. we argue that it is not possible, from fitting only existing data for forward scattering, to select a definite asymptotic growth with the energy of $ \ sigma _ { tot } $. we find equivalent fits to the data together with a logarithmic pomeron giving a behavior $ \ sigma _ { tot } \ propto \ ln ^ \ gamma s $, $ \ gamma \ in [ 0. 5, 2. 20 ] $ and with a supercritical pomeron giving a behavior $ \ sigma _ { tot } \ propto s ^ \ epsilon $, $ \ epsilon \ in [ 0. 01, 0. 10 ] $. | arxiv:hep-ph/9706306 |
recently, synthetic data - based instance segmentation has become an exceedingly favorable optimization paradigm since it leverages simulation rendering and physics to generate high - quality image - annotation pairs. in this paper, we propose a parallel pre - trained transformers ( ppt ) framework to accomplish the synthetic data - based instance segmentation task. specifically, we leverage the off - the - shelf pre - trained vision transformers to alleviate the gap between natural and synthetic data, which helps to provide good generalization in the downstream synthetic data scene with few samples. swin - b - based cbnet v2, swinl - based cbnet v2 and swin - l - based uniformer are employed for parallel feature learning, and the results of these three models are fused by pixel - level non - maximum suppression ( nms ) algorithm to obtain more robust results. the experimental results reveal that ppt ranks first in the cvpr2022 ava accessibility vision and autonomy challenge, with a 65. 155 % map. | arxiv:2206.10845 |
in this paper, we approach the challenging problem of motion planning for knot tying. we propose a hierarchical approach in which the top layer produces a topological plan and the bottom layer translates this plan into continuous robot motion. the top layer decomposes a knotting task into sequences of abstract topological actions based on knot theory. the bottom layer translates each of these abstract actions into robot motion trajectories through learned topological motion primitives. to adapt each topological action to the specific rope geometry, the motion primitives take the observed rope configuration as input. we train the motion primitives by imitating human demonstrations and reinforcement learning in simulation. to generalize human demonstrations of simple knots into more complex knots, we observe similarities in the motion strategies of different topological actions and design the neural network structure to exploit such similarities. we demonstrate that our learned motion primitives can be used to efficiently generate motion plans for tying the overhand knot. the motion plan can then be executed on a real robot using visual tracking and model predictive control. we also demonstrate that our learned motion primitives can be composed to tie a more complex pentagram - like knot despite being only trained on human demonstrations of simpler knots. | arxiv:2009.02615 |
implicit neural networks have been successfully used for surface reconstruction from point clouds. however, many of them face scalability issues as they encode the isosurface function of a whole object or scene into a single latent vector. to overcome this limitation, a few approaches infer latent vectors on a coarse regular 3d grid or on 3d patches, and interpolate them to answer occupancy queries. in doing so, they loose the direct connection with the input points sampled on the surface of objects, and they attach information uniformly in space rather than where it matters the most, i. e., near the surface. besides, relying on fixed patch sizes may require discretization tuning. to address these issues, we propose to use point cloud convolutions and compute latent vectors at each input point. we then perform a learning - based interpolation on nearest neighbors using inferred weights. experiments on both object and scene datasets show that our approach significantly outperforms other methods on most classical metrics, producing finer details and better reconstructing thinner volumes. the code is available at https : / / github. com / valeoai / poco. | arxiv:2201.01831 |
active colloids and externally actuated semi - flexible filaments provide basic building blocks for designing autonomously motile micro - machines. here, we show that a passive semi - flexible filament can be actuated and transported by attaching an active colloid to its terminus. we study the dynamics of this assembly when it is free, tethered, or clamped using overdamped equations of motion that explicitly account for active fluid flow and the forces it mediates. linear states are destabilized by buckling instabilities to produce stable states of non - zero curvature and writhe. we demarcate boundaries of these states in the two - dimensional parameter space representing dimensionless measures of polar and apolar activity. our proposed assembly can be used as a novel component in the design of micro - machines at low reynolds number and to study elastic instabilities driven by " follower " forces. | arxiv:1612.06196 |
in this expository paper we explain in detail how to construct bicategorical colimits of several kinds of tensor categories, for example essentially small finitely cocomplete k - linear tensor categories. the constructions are direct and elementary. | arxiv:2001.10123 |
the aim of this note is to present a numerical method to solve the stokes problem in a bounded domain with a dirac source term, which preserves optimality for any approximation order by the finite - element method. it is based on the knowledge of a fundamental solution to the associated operator over the whole space. this method is motivated by the modeling of the movement of active thin structures in a viscous fluid. | arxiv:1505.03047 |
we study the proximity effect between the fully - gapped region of a topological insulator in direct contact with an s - wave superconducting electrode ( sti ) and the surrounding topological insulator flake ( ti ) in au / bi $ _ { 1. 5 } $ sb $ _ { 0. 5 } $ te $ _ { 1. 7 } $ se $ _ { 1. 3 } $ / nb devices. the conductance spectra of the devices show the presence of a large induced gap in the sti as well as the induction of superconducting correlations in the normal part of the ti on the order of the thouless energy. the shape of the conductance modulation around zero - energy varies between devices and can be explained by existing theory of s - wave - induced superconductivity in snn ' ( s is a superconductor, n a superconducting proximized material and n ' is a normal metal ) devices. all the conductance spectra show a conductance dip at the induced gap of the sti. | arxiv:1506.05923 |
we consider rg interfaces for boundary rg flows in two - dimensional qfts. such interfaces are particular boundary condition changing operators linking the uv and ir conformal boundary conditions. we refer to them as rg operators. in this paper we study their general properties putting forward a number of conjectures. we conjecture that an rg operator is always a conformal primary such that the ope of this operator with its conjugate must contain the perturbing uv operator when taken in one order and the leading irrelevant operator ( when it exists ) along which the flow enters the ir fixed point, when taken in the other order. we support our conjectures by perturbative calculations for flows between nearby fixed points, by a non - perturbative variational method inspired by the variational method proposed by j. ~ cardy for massive rg flows, and by numerical results obtained using boundary tcsa. the variational method has a merit of its own as it can be used as a first approximation in charting the global structure of the space of boundary rg flows. we also discuss the role of the rg operators in the transport of states and local operators. some of our considerations can be generalised to two - dimensional bulk flows, clarifying some conceptual issues related to the rg interface put forward by d. ~ gaiotto for bulk $ \ phi _ { 1, 3 } $ flows. | arxiv:2012.12361 |
the scattering of a wave obeying helmholtz equation by an elliptic obstacle can be described exactly using series of mathieu functions. this situation is relevant in optics, quantum mechanics and fluid dynamics. we focus on the case when the wavelength is comparable to the obstacle size, when the most standard approximations fail. the approximations of the radial ( or modified ) mathieu functions using wkb method are shown to be especially efficient, in order to precisely evaluate series of such functions. it is illustrated with the numerical computation of the green function when the wave is scattered by a single slit or a strip ( ribbon ). | arxiv:1708.03195 |
studying potential bsm effects at the precision frontier requires accurate transfer of information from low - energy measurements to high - energy bsm models. we propose to use normalising flows to construct likelihood functions that achieve this transfer. likelihood functions constructed in this way provide the means to generate additional samples and admit a ` ` trivial ' ' goodness - of - fit test in form of a $ \ chi ^ 2 $ test statistic. here, we study a particular form of normalising flow, apply it to a multi - modal and non - gaussian example, and quantify the accuracy of the likelihood function and its test statistic. | arxiv:2309.10365 |
we derive noncommutative einstein equations for abelian twists and their solutions in consistently symmetry reduced sectors, corresponding to twisted frw cosmology and schwarzschild black holes. while some of these solutions must be rejected as models for physical spacetimes because they contradict observations, we find also solutions that can be made compatible with low energy phenomenology, while exhibiting strong noncommutativity at very short distances and early times. | arxiv:0906.2730 |
most coding theorems in quantum shannon theory can be proven using the decoupling technique : to send data through a channel, one guarantees that the environment gets no information about it ; uhlmann ' s theorem then ensures that the receiver must be able to decode. while a wide range of problems can be solved this way, one of the most basic coding problems remains impervious to a direct application of this method : sending classical information through a quantum channel. we will show that this problem can, in fact, be solved using decoupling ideas, specifically by proving a " dequantizing " theorem, which ensures that the environment is only classically correlated with the sent data. our techniques naturally yield a generalization of the holevo - schumacher - westmoreland theorem to the one - shot scenario, where a quantum channel can be applied only once. | arxiv:1207.0067 |
we show that partial transposition for pure and mixed two - particle states in a discrete $ n $ - dimensional hilbert space is equivalent to a change in sign of a " momentum - like " variable of one of the particles in the wigner function for the state. this generalizes a result obtained for continuous - variable systems to the discrete - variable system case. we show that, in principle, quantum mechanics allows measuring the expectation value of an observable in a partially transposed state, in spite of the fact that the latter may not be a physical state. we illustrate this result with the example of an " isotropic state ", which is dependent on a parameter $ r $, and an operator whose variance becomes negative for the partially transposed state for certain values of $ r $ ; for such $ r $, the original states are entangled. | arxiv:1705.09613 |
we report on the properties of eclipsing binaries from the kepler mission with a newly developed photometric modeling code, which uses the light curve, spectral energy distribution of each binary, and stellar evolution models to infer stellar masses without the need for radial velocity measurements. we present solutions and posteriors to orbital and stellar parameters for 728 systems, forming the largest homogeneous catalogue of full kepler binary parameter estimates to date. using comparisons to published radial velocity measurements, we demonstrate that the inferred properties ( e. g., masses ) are reliable for well - detached main - sequence binaries, which make up the majority of our sample. the fidelity of our inferred parameters degrades for a subset of systems not well described by input isochrones, such as short - period binaries that have undergone interactions, or binaries with post - main sequence components. additionally, we identify 35 new systems which show evidence of eclipse timing variations, perhaps from apsidal motion due to binary tides or tertiary companions. we plan to subsequently use these models to search for and constrain the presence of circumbinary planets in kepler eclipsing binary systems. | arxiv:1908.00139 |
domain adaptation is a common problem in robotics, with applications such as transferring policies from simulation to real world and lifelong learning. performing such adaptation, however, requires informative data about the environment to be available during the adaptation. in this paper, we present domain curiosity - - a method of training exploratory policies that are explicitly optimized to provide data that allows a model to learn about the unknown aspects of the environment. in contrast to most curiosity methods, our approach explicitly rewards learning, which makes it robust to environment noise without sacrificing its ability to learn. we evaluate the proposed method by comparing how much a model can learn about environment dynamics given data collected by the proposed approach, compared to standard curious and random policies. the evaluation is performed using a toy environment, two simulated robot setups, and on a real - world haptic exploration task. the results show that the proposed method allows data - efficient and accurate estimation of dynamics. | arxiv:2103.07223 |
we construct and give a complete classification of all the differential symmetry breaking operators $ \ mathbb { d } _ { \ lambda, \ nu } ^ { n, m } : c ^ \ infty ( s ^ 3, \ mathcal { v } _ \ lambda ^ { 2n + 1 } ) \ rightarrow c ^ \ infty ( s ^ 2, \ mathcal { l } _ { m, \ nu } ) $, between the spaces of smooth sections of a vector bundle of rank $ 2n + 1 $ over the $ 3 $ - sphere $ \ mathcal { v } _ \ lambda ^ { 2n + 1 } \ rightarrow s ^ 3 $, and a line bundle over the $ 2 $ - sphere $ \ mathcal { l } _ { m, \ nu } \ rightarrow s ^ 2 $ in the special case $ | m | = n $. | arxiv:2504.01977 |
modeling structure in complex networks using bayesian non - parametrics makes it possible to specify flexible model structures and infer the adequate model complexity from the observed data. this paper provides a gentle introduction to non - parametric bayesian modeling of complex networks : using an infinite mixture model as running example we go through the steps of deriving the model as an infinite limit of a finite parametric model, inferring the model parameters by markov chain monte carlo, and checking the model ' s fit and predictive performance. we explain how advanced non - parametric models for complex networks can be derived and point out relevant literature. | arxiv:1312.5889 |
i develop the theory around using control functions to instrument hazard models, allowing the inclusion of endogenous ( e. g., mismeasured ) regressors. simple discrete - data hazard models can be expressed as binary choice panel data models, and the widespread prentice and gloeckler ( 1978 ) discrete - data proportional hazards model can specifically be expressed as a complementary log - log model with time fixed effects. this allows me to recast it as gmm estimation and its instrumented version as sequential gmm estimation in a z - estimation ( non - classical gmm ) framework ; this framework can then be leveraged to establish asymptotic properties and sufficient conditions. whilst this paper focuses on the prentice and gloeckler ( 1978 ) model, the methods and discussion developed here can be applied more generally to other hazard models and binary choice models. i also introduce my stata command for estimating a complementary log - log model instrumented via control functions ( available as ivcloglog on ssc ), which allows practitioners to easily instrument the prentice and gloeckler ( 1978 ) model. | arxiv:2312.03165 |
over more than a decade there has been an extensive research effort on how to effectively utilize recurrent models and attention. while recurrent models aim to compress the data into a fixed - size memory ( called hidden state ), attention allows attending to the entire context window, capturing the direct dependencies of all tokens. this more accurate modeling of dependencies, however, comes with a quadratic cost, limiting the model to a fixed - length context. we present a new neural long - term memory module that learns to memorize historical context and helps attention to attend to the current context while utilizing long past information. we show that this neural memory has the advantage of fast parallelizable training while maintaining a fast inference. from a memory perspective, we argue that attention due to its limited context but accurate dependency modeling performs as a short - term memory, while neural memory due to its ability to memorize the data, acts as a long - term, more persistent, memory. based on these two modules, we introduce a new family of architectures, called titans, and present three variants to address how one can effectively incorporate memory into this architecture. our experimental results on language modeling, common - sense reasoning, genomics, and time series tasks show that titans are more effective than transformers and recent modern linear recurrent models. they further can effectively scale to larger than 2m context window size with higher accuracy in needle - in - haystack tasks compared to baselines. | arxiv:2501.00663 |
we compute from first principles the effective interaction parameters appropriate for a low - energy description of the rare - earth nickelate lunio $ _ { 3 } $ involving the partially occupied $ e _ g $ states only. the calculation uses the constrained random - phase approximation and reveals that the effective on - site coulomb repulsion is strongly reduced by screening effects involving the oxygen - $ p $ and nickel - $ t _ { 2g } $ states. the long - range component of the effective low - energy interaction is also found to be sizeable. as a result, the effective on - site interaction between parallel - spin electrons is reduced down to a small negative value. this validates effective low - energy theories of these materials proposed earlier. electronic structure methods combined with dynamical mean - field theory are used to construct and solve an appropriate low - energy model and explore its phase diagram as a function of the on - site repulsion and hund ' s coupling. for the calculated values of these effective interactions we find, in agreement with experiments, that lunio $ _ { 3 } $ is a metal without disproportionation of the $ e _ g $ occupancy when considered in its orthorhombic structure, while the monoclinic phase is a disproportionated insulator. | arxiv:1707.09820 |
the pursuit of artificial general intelligence ( agi ) has been accelerated by multimodal large language models ( mllms ), which exhibit superior reasoning, generalization capabilities, and proficiency in processing multimodal inputs. a crucial milestone in the evolution of agi is the attainment of human - level planning, a fundamental ability for making informed decisions in complex environments, and solving a wide range of real - world problems. despite the impressive advancements in mllms, a question remains : how far are current mllms from achieving human - level planning? to shed light on this question, we introduce egoplan - bench, a comprehensive benchmark to evaluate the planning abilities of mllms in real - world scenarios from an egocentric perspective, mirroring human perception. egoplan - bench emphasizes the evaluation of planning capabilities of mllms, featuring realistic tasks, diverse action plans, and intricate visual observations. our rigorous evaluation of a wide range of mllms reveals that egoplan - bench poses significant challenges, highlighting a substantial scope for improvement in mllms to achieve human - level task planning. to facilitate this advancement, we further present egoplan - it, a specialized instruction - tuning dataset that effectively enhances model performance on egoplan - bench. we have made all codes, data, and a maintained benchmark leaderboard available to advance future research. | arxiv:2312.06722 |
we propose using a dielectric beveled nozzle for electrospray and electrohydrodynamic jet printing. this nozzle stabilizes the liquid ejection of low - conductivity liquids, considerably reducing the minimum flow rate below which the flow becomes unstable. this translates into a significant reduction of the minimum jet diameter. due to its dielectric character, electrochemical reactions occurring in metallic beveled nozzles ( e. g. hypodermic needles ) do not occur, preserving the purity of the liquid. this property makes this nozzle appropriate for electrospray ionization mass spectrometry ( esi - ms ) or bioplotting. we illustrate the capabilities of this new technique by conducting ( i ) electrospray experiments with newtonian liquids and ( ii ) electrohydrodynamic jet printing experiments with viscoelastic fluids. jets with diameters around 1 $ \ mu $ m are produced with low - conductivity liquids such as octanol and glycerine. viscoelastic threads a few microns in diameter are gently deposited on a moving substrate to print out uniform lines tens of nanometers in height. due to the strong stabilizing effect of the beveled nozzle, the minimum flow rate and jet diameter were much smaller than the respective values obtained with the cylindrical capillary in the electrospray and electrohydrodynamic jet printing experiments. the proposed technique opens new routes for electrospray and electrohydrodynamic jet printing. | arxiv:2503.15010 |
computational fluid dynamic simulations often produce large clusters of finite elements with non - trivial, non - convex boundaries and uneven distributions among compute nodes, posing challenges to compositing during interactive volume rendering. correct, in - place visualization of such clusters becomes difficult because viewing rays straddle domain boundaries across multiple compute nodes. we propose a gpu - based, scalable, memory - efficient direct volume visualization framework suitable for in ~ situ and post ~ hoc usage. our approach reduces memory usage of the unstructured volume elements by leveraging an exclusive or - based index reduction scheme and provides fast ray - marching - based traversal without requiring large external data structures built over the elements themselves. moreover, we present a gpu - optimized deep compositing scheme that allows correct order compositing of intermediate color values accumulated across different ranks that works even for non - convex clusters. our method scales well on large data - parallel systems and achieves interactive frame rates during visualization. we can interactively render both fun3d small mars lander ( 14 gb / 798. 4 million finite elements ) and huge mars lander ( 111. 57 gb / 6. 4 billion finite elements ) data sets at 14 and 10 frames per second using 72 and 80 gpus, respectively, on tacc ' s frontera supercomputer. | arxiv:2209.14537 |
by adding a particle source term in the boltzmann equation of kinetic theory, it is possible to represent particles appearing and disappearing throughout the fluid with a specified distribution of particle velocities. by deriving the wave equation from this modified boltzmann equation via the conservation equations of fluid mechanics, multipole source terms in the wave equation are found. these multipole source terms are given by the particle source term in the boltzmann equation. to the euler level in the momentum equation, a monopole and a dipole source term appear in the wave equation. to the navier - stokes level, a quadrupole term with negligible magnitude also appears. | arxiv:1302.3764 |
the coupling strengths for intra - and inter - band electron - phonon pair scattering are calculated for lifeas. while the sum of these couplings, which gives the total electron - phonon coupling $ \ lambda $, is of order 0. 2, we find that their contribution to the presumed $ s ^ \ pm $ superconducting state is reduced by approximately an order of magnitude. | arxiv:1306.2925 |
we have a knot quandle and a fundamental class as invariants for a surface - knot. these invariants can be defined for a classical knot in a similar way, and it is known that the pair of them is a complete invariant for classical knots. in this paper, we compare a situation in surface - knot theory with that in classical knot theory, and prove the following : there exist arbitrarily many inequivalent surface - knots of genus $ g $ with the same knot quandle, and there exist two inequivalent surface - knots of genus $ g $ with the same knot quandle and with the same fundamental class. | arxiv:math/0512099 |
the transition constant for the hadronic decay $ \ omega \ rightarrow \ rho \ pi $ is investigated by means of qcd sum rules in external axial field. the obtained value for $ g _ { \ omega \ rho \ pi } $ is about 16 gev $ { } ^ { - 1 } $ that is in a good agreement with experimental data. | arxiv:hep-ph/9608331 |
vibrational energy transfer from photo - excited single - wall carbon nanotubes ( swcnts ) to coupled proteins is a key to engineer thermally induced biological reactions such as photothermal therapy. here, we explored vibrational energy transfer from the photo - excited swcnts to different adsorbed biological materials by means of a femtosecond pump - probe technique. we show that the vibrational relaxation time of the radial breathing modes ( rbms ) in swcnts significantly depends on the structure of coupled materials, i. e. proteins or biopolymers, indicating the vibrational energy transfer is governed by overlap of phonon density of states between the swcnts and coupled materials. | arxiv:1712.02622 |
we study the nanoscale behaviour of the density of a simple fluid in the vicinity of an equilibrium contact line for a wide range of young contact angles between 40 and 135 degrees. cuts of the density profile at various positions along the contact line are presented, unravelling the apparent step - wise increase of the film height profile observed in contour plots of the density. the density profile is employed to compute the normal pressure acting on the substrate along the contact line. we observe that for the full range of contact angles, the maximal normal pressure cannot solely be predicted by the curvature of the adsorption film height, but is instead softened - - likely by the width of the liquid - vapour interface. somewhat surprisingly however, the adsorption film height profile can be predicted to a very good accuracy by the derjaguin - frumkin disjoining pressure obtained from planar computations, as was first shown in [ nold et al., phys. fluids, 26, 072001, 2014 ] for contact angles less than 90 degrees, a result which here we show to be valid for the full range of contact angles. this suggests that while two - dimensional effects cannot be neglected for the computation of the normal pressure distribution along the substrate, one - dimensional planar computations of the derjaguin - frumkin disjoining pressure are sufficient to accurately predict the adsorption height profile. | arxiv:1503.03232 |
dis data from hera show a striking regularity as \ sigma ^ { \ gamma ^ * p } is a function of the ratio \ tau = q ^ 2 / q _ s ^ 2 ( x ) only. the scaling function shows a break at \ tau ~ 1, which has been taken as an indication for saturation. however, besides saturation also the transition between dominance of k _ t - ordered ( dglap ) and k _ t - non - ordered ( bfkl ) evolution contributes to a break around this value of \ tau, as well as the suppression for small q ^ 2 due to finite quark masses and confinement. in this paper we use a dipole cascade model based on mueller ' s dipole model, which also includes energy conservation and pomeron mergins, to investigate the contributions of these different effects to the scaling behaviour. as a result we predict that the scaling function for \ tau < 1 will be modified when data for q ^ 2 > 1 gev ^ 2 become available. we also investigate the scaling properties of the charm contribution and the impact parameter dependence of the saturation scale. | arxiv:hep-ph/0702087 |
the global requirements for energy are increasing rapidly as the global population increases and the under - developed nations become more advanced. the traditional fuels used in their traditional ways will become increasingly unable to meet the demand. the need for a review of the energy sources available is paramount, although the subsequent need to develop a realistic strategy to deal with all local and global energy requirements is almost as important. here attention will be restricted to examining some of the claims and problems of using nuclear power to attempt to solve this major question. | arxiv:physics/0406046 |
vector leptoquarks can address the lepton flavor universality anomalies in decays associated with the $ b \ to c \ ell \ nu $ and $ b \ to s \ ell \ ell $ transitions, as observed in recent years. generically, these leptoquarks yield new sources of cp violation. in this paper, we explore constraints and discovery potential for electric dipole moments ( edms ) in leptonic and hadronic systems. we provide the most generic expressions for dipole moments induced by vector leptoquarks at one loop. we find that $ o ( 1 ) $ cp - violating phases in tau and muon couplings can lead to corresponding edms within reach of next - generation edm experiments, and that existing bounds on the electron edm already put stringent constraints on cp - violating electron couplings. | arxiv:2002.01400 |
we develop a formal model for distributed measurement - based quantum computations, adopting an agent - based view, such that computations are described locally where possible. because the network quantum state is in general entangled, we need to model it as a global structure, reminiscent of global memory in classical agent systems. local quantum computations are described as measurement patterns. since measurement - based quantum computation is inherently distributed, this allows us to extend naturally several concepts of the measurement calculus, a formal model for such computations. our goal is to define an assembly language, i. e. we assume that computations are well - defined and we do not concern ourselves with verification techniques. the operational semantics for systems of agents is given by a probabilistic transition system, and we define operational equivalence in a way that it corresponds to the notion of bisimilarity. with this in place, we prove that teleportation is bisimilar to a direct quantum channel, and this also within the context of larger networks. | arxiv:quant-ph/0506070 |
we study general aspects of the reductive dual pair correspondence, also known as howe duality. we make an explicit and systematic treatment, where we first derive the oscillator realizations of all irreducible dual pairs : $ ( gl ( m, \ mathbb r ), gl ( n, \ mathbb r ) ) $, $ ( gl ( m, \ mathbb c ), gl ( n, \ mathbb c ) ) $, $ ( u ^ * ( 2m ), u ^ * ( 2n ) ) $, $ ( u ( m _ +, m _ - ), u ( n _ +, n _ - ) ) $, $ ( o ( n _ +, n _ - ), sp ( 2m, \ mathbb r ) ) $, $ ( o ( n, \ mathbb c ), sp ( 2m, \ mathbb c ) ) $ and $ ( o ^ * ( 2n ), sp ( m _ +, m _ - ) ) $. then, we decompose the fock space into irreducible representations of each group in the dual pairs for the cases where one member of the pair is compact as well as the first non - trivial cases of where it is non - compact. we discuss the relevance of these representations in several physical applications throughout this analysis. in particular, we discuss peculiarities of their branching properties. finally, closed - form expressions relating all casimir operators of two groups in a pair are established. | arxiv:2006.07102 |
in the aharonov - bohm setup, a double - slit experiment, coherent beams of electrons passing through two slits form an interference pattern on the observing screen. however, when a long but thin solenoid of current is introduced behind the slits between the two electron beams, an extra phase difference between them appears, as shown by a shift in the interference pattern. this happens even though there is no magnetic field outside the solenoid, at the location of the beams. this mysterious effect, purportedly arises owing to an electromagnetic momentum, attributed to the presence at the location of either beam, a vector potential due to the solenoid of current even when there exists no magnetic field outside the solenoid. the first experimental confirmation came soon and it has since been amply verified using clever experimental setups, leaving hardly any doubts that the observed effect is real. however, on the theoretical side the picture is not so clear and a satisfactory physical explanation of the existence of momentum, at least under the aegis of classical electromagnetism, is still missing since inception of the idea more than half a century back. it has remained a puzzle, how just potential can give rise to an electromagnetic momentum in a system. we here show that a subtle momentum can be seen to lie in the product of the drift velocities of the current carrying charges and the mass equivalent of their non - localized potential energies in the electric field of the interfering electrons, which manifests, from a classical point of view, a linear momentum in the system. it is this hard - to - pinpoint, additional momentum, reflected through an extra phase difference between the interfering beams of electrons, which exhibits from a classical physics perspective, the presence of an elusive, long sought - after electromagnetic momentum in the system. | arxiv:2301.06502 |
models of relativistic particle with lagrangian $ { \ cal l } ( k _ 1 ) $, depending on the curvature of the worldline $ k _ 1 $, are considered. by making use of the frenet basis, the equations of motion are reformulated in terms of the principal curvatures of the worldline. it is shown that for arbitrary lagrangian function $ { \ cal l } ( k _ 1 ) $ these equations are completely integrable, i. e., the principal curvatures are defined by integrals. the constants of integration are the particle mass and its spin. the developed method is applied to the study of a model of relativistic particle with maximal proper acceleration, whose lagrangian is uniquely determined by a modified form of the invariant relativistic interval. this model gives us an example of a consistent relativistic dynamics obeying the principle of a superiorly limited value of the acceleration, advanced recently. | arxiv:hep-th/9408071 |
band structure determines the motion of electrons in a solid, giving rise to exotic phenomena when properly engineered. drawing an analogy between electrons and photons, artificially designed optical lattices indicate the possibility of a similar band modulation effect in graphene systems. yet due to the fermionic nature of electrons, modulated electronic systems promise far richer categories of behaviors than those found in optical lattices. here, we uncovered a strong modulation of electronic states in bilayer graphene subject to periodic potentials. we observed for the first time the hybridization of electron and hole sub - bands, resulting in local band gaps at both primary and secondary charge neutrality points. such hybridization leads to the formation of flat bands, enabling the study of correlated effects in graphene systems. this work may also offer a viable platform to form and continuously tune majorana zero modes, which is important to the realization of topological quantum computation. | arxiv:1910.14126 |
suppose y is an integer homology 3 - sphere, taubes proved that the number of irreducible critical orbits of the perturbed chern - simons functional on y, counted with signs, is equal to the algebraic intersection number of two character varieties associated with heegaard splittings when the structure group is su ( 2 ). taubes ' result established a relationship between gauge theory and the casson invariant. this article proves an analogous identification result for su ( n ) generalized casson invariants. as a special case, we show that the su ( 3 ) casson invariant of boden - herald can be equivalently calculated by taking an appropriate intersection number of lagrangian submanifolds. | arxiv:2102.03665 |
major stellar - wind emission features in the spectrum of eta car have recently decreased by factors of order 2 relative to the continuum. this is unprecedented in the modern observational record. the simplest, but unproven, explanation is a rapid decrease in the wind density. | arxiv:1004.3529 |
we derive two estimates for the deviation of the $ n $ - particle, hard - spheres kac process from the corresponding boltzmann equation, measured in expected wasserstein distance. particular care is paid to the long - time properties of our estimates, exploiting the stability properties of the limiting boltzmann equation at the level of realisations of the interacting particle system. as a consequence, we obtain an estimate for the propagation of chaos, uniformly in time and with polynomial rates, as soon as the initial data has a $ k ^ \ mathrm { th } $ moment, $ k > 2 $. our approach is similar to kac ' s proposal of relating the long - time behaviour of the particle system to that of the limit equation. along the way, we prove a new estimate for the continuity of the boltzmann flow measured in wasserstein distance. | arxiv:1801.05791 |
the $ 4. 2 \ sigma $ discrepancy in the $ ( g - 2 ) $ of the muon provides a hint that may indicate that physics beyond the standard model is at play. a multi - tev scale muon collider provides a natural testing ground for this physics. in this paper, we discuss the potential to probe the bsm parameter space that is consistent with solving the $ ( g - 2 ) _ { \ mu } $ discrepancy in the language of the smeft, utilizing the statistical power provided by fitting event rates collected running at multiple energies. our results indicate the importance of including interference between the bsm and the sm amplitudes, and illustrates how a muon collider running at a handful of lower energies and with less total collected luminosity can better significantly constrain the space of relevant smeft coefficients than would be possible for a single high energy run. | arxiv:2208.14464 |
in the old age, few people need special care if they are suffering from specific diseases as they can get stroke while they are in normal life routine. also patients of any age, who are not able to walk, need to be taken care of personally but for this, either they have to be in hospital or someone like nurse should be with them for better care. this is costly in terms of money and man power. a person is needed for 24x7 care of these people. to help in this aspect we purposes a vision based system which will take input from the patient and will provide information to the specified person, who is currently may not in the patient room. this will reduce the need of man power, also a continuous monitoring would not be needed. the system is using ms kinect for gesture detection for better accuracy and this system can be installed at home or hospital easily. the system provides gui for simple usage and gives visual and audio feedback to user. this system work on natural hand interaction and need no training before using and also no need to wear any glove or color strip. | arxiv:1409.2153 |
we study the wu metric on convex egg domains of the form \ [ e _ { 2m } = \ big \ { z \ in \ mathbb { c } ^ n : \ vert z _ 1 \ vert ^ { 2m } + \ vert z _ 2 \ vert ^ 2 + \ ldots + \ vert z _ { n - 1 } \ vert ^ 2 + \ vert z _ n \ vert ^ { 2 } < 1 \ big \ } \ ] where $ m \ geq 1 / 2, m \ neq 1 $. the wu metric is shown to be real analytic everywhere except on a lower dimensional subvariety where it fails to be $ c ^ 2 $ - smooth. overall however, the wu metric is shown to be continuous when $ m = 1 / 2 $ and even $ c ^ 1 $ - smooth for each $ m > 1 / 2 $, and in all cases, a non - k \ " ahler hermitian metric with its holomorphic curvature strongly negative in the sense of currents. this gives a natural answer to a conjecture of s. kobayashi and h. wu for such $ e _ { 2m } $. | arxiv:1503.02787 |
the effects of $ \ phi $ - meson on properties of hyperon stars are studied systematically in the framework of the density dependent relativistic mean field ( ddrmf ) model. the $ \ phi $ - meson shifts hyperon threshold to a higher density and reduces the hyperon fractions in neutron star cores. it also strongly stiffens the equation of state ( eos ) calculated with various ddrmf effective interactions and increases the maximum mass of hyperon stars, but only a few effective interactions survive under the constraints from recent astrophysical observations. in the ddrmf model, the conformal limit of sound velocity is still in a strong tension with the fact that the maximum mass of neutron stars obtained in theoretical calculations reaches about two solar masses. based on different interior composition assumptions, we discuss the possibility of the secondary object of gw190814 as a neutron star. when $ \ phi $ - meson is considered, dd - me2 and dd - mex support that the secondary object of gw190814 is a hyperon star rapidly rotating with kepler frequency. | arxiv:2109.07678 |
in the rapidly evolving domain of electrical power systems, the volt - var optimization ( vvo ) is increasingly critical, especially with the burgeoning integration of renewable energy sources. traditional approaches to learning - based vvo in expansive and dynamically changing power systems are often hindered by computational complexities. to address this challenge, our research presents a novel framework that harnesses the potential of deep reinforcement learning ( drl ), specifically utilizing the importance weighted actor - learner architecture ( impala ) algorithm, executed on the ray platform. this framework, built upon rllib - an industry - standard in reinforcement learning - ingeniously capitalizes on the distributed computing capabilities and advanced hyperparameter tuning offered by ray. this design significantly expedites the exploration and exploitation phases in the vvo solution space. our empirical results demonstrate that our approach not only surpasses existing drl methods in achieving superior reward outcomes but also manifests a remarkable tenfold reduction in computational requirements. the integration of our drl agent with the ray platform facilitates the creation of rllib - impala, a novel framework that efficiently uses ray ' s resources to improve system adaptability and control. rllib - impala leverages ray ' s toolkit to enhance analytical capabilities and significantly speeds up training to become more than 10 times faster than other state - of - the - art drl methods. | arxiv:2402.15932 |
scattering of anisotropic radiation by atoms, ions or molecules is sufficient to generate linear polarization observable in stars and planets atmospheres, circumstellar environments, and in particular in the sun ' s atmosphere. this kind of polarization is called scattering polarization ( sp ) or second solar spectrum ( sss ) if it is formed near the limb of the solar photosphere. generation of linear sp can typically be reached more easily than circular sp. interestingly, the later is often absent in observations and theories. intrigued by this, we propose to demonstrate how circular sp can be created by anisotropic collisions if a magnetic field is present. we also demonstrate how anisotropic collisions can result in the creation of circular sp if the radiation field is anisotropic. we show that under certain conditions, linear sp creation is accompanied by the emergence of circular sp which can be useful for diagnostics of solar and astrophysical plasmas. we treat an example and calculate the density matrix elements of tensorial order $ k \! = \! 1 $ which are directly associated with the presence of circular sp. this work should encourage theoretical and observational research to be increasingly oriented towards circular sp profiles in addition to linear sp in order to improve our analysis tools of astrophysical and solar observations. | arxiv:2010.06982 |
after the phenomenal success of the pagerank algorithm, many researchers have extended the pagerank approach to ranking graphs with richer structures beside the simple linkage structure. in some scenarios we have to deal with multi - parameters data where each node has additional features and there are relationships between such features. this paper stems from the need of a systematic approach when dealing with multi - parameter data. we propose models and ranking algorithms which can be used with little adjustments for a large variety of networks ( bibliographic data, patent data, twitter and social data, healthcare data ). in this paper we focus on several aspects which have not been addressed in the literature : ( 1 ) we propose different models for ranking multi - parameters data and a class of numerical algorithms for efficiently computing the ranking score of such models, ( 2 ) by analyzing the stability and convergence properties of the numerical schemes we tune a fast and stable technique for the ranking problem, ( 3 ) we consider the issue of the robustness of our models when data are incomplete. the comparison of the rank on the incomplete data with the rank on the full structure shows that our models compute consistent rankings whose correlation is up to 60 % when just 10 % of the links of the attributes are maintained suggesting the suitability of our model also when the data are incomplete. | arxiv:1504.07766 |
due to severe mathematical modeling and calibration difficulties open - loop feedforward control is mainly employed today for wastewater denitrification, which is a key ecological issue. in order to improve the resulting poor performances a new model - free control setting and its corresponding " intelligent " controller are introduced. the pitfall of regulating two output variables via a single input variable is overcome by introducing also an open - loop knowledge - based control deduced from the plant behavior. several convincing computer simulations are presented and discussed. | arxiv:1703.05278 |
we consider the problem of traveling among random points in euclidean space, when only a random fraction of the pairs are joined by traversable connections. in particular, we show a threshold for a pair of points to be connected by a geodesic of length arbitrarily close to their euclidean distance, and analyze the minimum length traveling salesperson tour, extending the beardwood - halton - hammersley theorem to this setting. | arxiv:1411.6596 |
in this paper, we use a simple discrete dynamical model to study partitions of integers into powers of another integer. we extend and generalize some known results about their enumeration and counting, and we give new structural results. in particular, we show that the set of these partitions can be ordered in a natural way which gives the distributive lattice structure to this set. we also give a tree structure which allow efficient and simple enumeration of the partitions of an integer. | arxiv:2101.08312 |
the objective of radiology report generation ( rrg ) is to automatically generate coherent textual analyses of diseases based on radiological images, thereby alleviating the workload of radiologists. current ai - based methods for rrg primarily focus on modifications to the encoder - decoder model architecture. to advance these approaches, this paper introduces an organ - regional information driven ( orid ) framework which can effectively integrate multi - modal information and reduce the influence of noise from unrelated organs. specifically, based on the llava - med, we first construct an rrg - related instruction dataset to improve organ - regional diagnosis description ability and get the llava - med - rrg. after that, we propose an organ - based cross - modal fusion module to effectively combine the information from the organ - regional diagnosis description and radiology image. to further reduce the influence of noise from unrelated organs on the radiology report generation, we introduce an organ importance coefficient analysis module, which leverages graph neural network ( gnn ) to examine the interconnections of the cross - modal information of each organ region. extensive experiments an1d comparisons with state - of - the - art methods across various evaluation metrics demonstrate the superior performance of our proposed method. | arxiv:2411.13025 |
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