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deep learning has emerged as a promising approach for learning the nonlinear mapping between diffusion - weighted mr images and tissue parameters, which enables automatic and deep understanding of the brain microstructures. however, the efficiency and accuracy in the multi - parametric estimations are still limited since previous studies tend to estimate multi - parametric maps with dense sampling and isolated signal modeling. this paper proposes deepmpmri, a unified framework for fast and high - fidelity multi - parametric estimation from various diffusion models using sparsely sampled q - space data. deepmpmri is equipped with a newly designed tensor - decomposition - based regularizer to effectively capture fine details by exploiting the correlation across parameters. in addition, we introduce a nesterov - based adaptive learning algorithm that optimizes the regularization parameter dynamically to enhance the performance. deepmpmri is an extendable framework capable of incorporating flexible network architecture. experimental results demonstrate the superiority of our approach over 5 state - of - the - art methods in simultaneously estimating multi - parametric maps for various diffusion models with fine - grained details both quantitatively and qualitatively, achieving 4. 5 - 22. 5 $ \ times $ acceleration compared to the dense sampling of a total of 270 diffusion gradients. | arxiv:2405.03159 |
we present a [ [ 7, 1, 3 ] ] quantum error - correcting code that is able to achieve fault - tolerant syndrome measurement using one ancillary qubit per stabilizer for an error model of independent single - qubit pauli errors. all single - qubit pauli errors on the ancillary qubits propagate to form exclusively correctable errors on the data qubits. the situation changes for error models with two - qubit pauli errors. we compare the level - 1 logical error rates under two noise models : the standard pauli symmetric depolarizing error model and an anisotropic error model. the anisotropic model is motivated by control errors on two - qubit gates commonly applied to trapped ion qubits. we find that one ancillary qubit per syndrome measurement is sufficient for fault - tolerance for the anisotropic error, but is not sufficient for the standard depolarizing errors. we then show how to achieve fault tolerance for the standard depolarizing errors by adding flag qubits to check for errors on select ancilary qubits. our results on this [ [ 7, 1, 3 ] ] code demonstrates how physically motivated noise models may simplify fault - tolerent protocols. | arxiv:1702.01155 |
we analyze the superconducting instabilities in the vicinity of the quantum - critical point of an inversion symmetry breaking order. we first show that the fluctuations of the inversion symmetry breaking order lead to two degenerate superconducting ( sc ) instabilities, one in the $ s $ - wave channel, and the other in a time - reversal invariant odd - parity pairing channel ( the simplest case being the same as the of $ ^ 3 $ he - b phase ). remarkably, we find that unlike many well - known examples, the selection of the pairing symmetry of the condensate is independent of the momentum - space structure of the collective mode that mediates the pairing interaction. we found that this degeneracy is a result of the existence of a conserved fermionic helicity, $ \ chi $, and the two degenerate channels correspond to even and odd combinations of sc order parameters with $ \ chi = \ pm1 $. as a result, the system has an enlarged symmetry $ u ( 1 ) \ times u ( 1 ) $, with each $ u ( 1 ) \ times u ( 1 ) $ corresponding to one value of the helicity $ \ chi $. because of the enlarged symmetry, this system admits exotic topological defects such as a fractional quantum vortex, which we show has a majorana zero mode bound at its core. we discuss how the enlarged symmetry can be lifted by small perturbations, such as the coulomb interaction or fermi surface splitting in the presence of broken inversion symmetry, and we show that the resulting superconducting state can be topological or trivial depending on parameters. the $ u ( 1 ) \ times u ( 1 ) $ symmetry is restored at the phase boundary between the topological and trivial sc states, and allows for a transition between topologically distinct sc phases without the vanishing of the order parameter. we present a global phase diagram of the superconducting states and discuss possible experimental implications. | arxiv:1602.02778 |
let $ \ f $ denote a field and let $ v $ denote a vector space over $ \ f $ with finite positive dimension. we consider a pair of linear transformations $ a : v \ to v $ and $ a ^ * : v \ to v $ that satisfy the following conditions : ( i ) each of $ a, a ^ * $ is diagonalizable ; ( ii ) there exists an ordering $ \ lbrace v _ i \ rbrace _ { i = 0 } ^ d $ of the eigenspaces of $ a $ such that $ a ^ * v _ i \ subseteq v _ { i - 1 } + v _ { i } + v _ { i + 1 } $ for $ 0 \ leq i \ leq d $, where $ v _ { - 1 } = 0 $ and $ v _ { d + 1 } = 0 $ ; ( iii ) there exists an ordering $ \ lbrace v ^ * _ i \ rbrace _ { i = 0 } ^ \ delta $ of the eigenspaces of $ a ^ * $ such that $ a v ^ * _ i \ subseteq v ^ * _ { i - 1 } + v ^ * _ { i } + v ^ * _ { i + 1 } $ for $ 0 \ leq i \ leq \ delta $, where $ v ^ * _ { - 1 } = 0 $ and $ v ^ * _ { \ delta + 1 } = 0 $ ; ( iv ) there is no subspace $ w $ of $ v $ such that $ aw \ subseteq w $, $ a ^ * w \ subseteq w $, $ w \ neq 0 $, $ w \ neq v $. we call such a pair a { \ it tridiagonal pair } on $ v $. it is known that $ d = \ delta $, and for $ 0 \ leq i \ leq d $ the dimensions of $ v _ i, v ^ * _ i, v _ { d - i }, v ^ * _ { d - i } $ coincide. denote this common dimension by $ \ rho _ i $ and call $ a, a ^ * $ { \ it sharp } whenever $ \ rho _ 0 = 1 $. let $ t $ denote the $ \ f $ - subalgebra of $ { \ rm end } _ \ f ( v ) $ generated by $ a, a | arxiv:0807.3990 |
the blind deconvolution problem seeks to recover a pair of vectors from a set of rank one bilinear measurements. we consider a natural nonsmooth formulation of the problem and show that under standard statistical assumptions, its moduli of weak convexity, sharpness, and lipschitz continuity are all dimension independent. this phenomenon persists even when up to half of the measurements are corrupted by noise. consequently, standard algorithms, such as the subgradient and prox - linear methods, converge at a rapid dimension - independent rate when initialized within constant relative error of the solution. we then complete the paper with a new initialization strategy, complementing the local search algorithms. the initialization procedure is both provably efficient and robust to outlying measurements. numerical experiments, on both simulated and real data, illustrate the developed theory and methods. | arxiv:1901.01624 |
the use of machine learning to investigate grasp affordances has received extensive attention over the past several decades. the existing literature provides a robust basis to build upon, though a number of aspects may be improved. results commonly work in terms of grasp configuration, with little consideration for the manner in which the grasp may be ( re - ) produced from a reachability and trajectory planning perspective. in addition, the majority of existing learning approaches focus of producing a single viable grasp, offering little transparency on how the result was reached, or insights on its robustness. we propose a different perspective on grasp affordance learning, explicitly accounting for grasp synthesis ; that is, the manner in which manipulator kinematics are used to allow materialization of grasps. the approach allows to explicitly map the grasp policy space in terms of generated grasp types and associated grasp quality. results of numerical simulations illustrate merit of the method and highlight the manner in which it may promote a greater degree of explainability for otherwise intransparent reinforcement processes. | arxiv:2405.04188 |
out - of - distribution ( ood ) detection is essential for the reliable and safe deployment of machine learning systems in the real world. great progress has been made over the past years. this paper presents the first review of recent advances in ood detection with a particular focus on natural language processing approaches. first, we provide a formal definition of ood detection and discuss several related fields. we then categorize recent algorithms into three classes according to the data they used : ( 1 ) ood data available, ( 2 ) ood data unavailable + in - distribution ( id ) label available, and ( 3 ) ood data unavailable + id label unavailable. third, we introduce datasets, applications, and metrics. finally, we summarize existing work and present potential future research topics. | arxiv:2305.03236 |
the recommendation system plays a vital role in many areas, especially academic fields, to support researchers in submitting and increasing the acceptance of their work through the conference or journal selection process. this study proposes a transformer - based model using transfer learning as an efficient approach for the paper submission recommendation system. by combining essential information ( such as the title, the abstract, and the list of keywords ) with the aims and scopes of journals, the model can recommend the top k journals that maximize the acceptance of the paper. our model had developed through two states : ( i ) fine - tuning the pre - trained language model ( lm ) with a simple contrastive learning framework. we utilized a simple supervised contrastive objective to fine - tune all parameters, encouraging the lm to learn the document representation effectively. ( ii ) the fine - tuned lm was then trained on different combinations of the features for the downstream task. this study suggests a more advanced method for enhancing the efficiency of the paper submission recommendation system compared to previous approaches when we respectively achieve 0. 5173, 0. 8097, 0. 8862, 0. 9496 for top 1, 3, 5, and 10 accuracies on the test set for combining the title, abstract, and keywords as input features. incorporating the journals ' aims and scopes, our model shows an exciting result by getting 0. 5194, 0. 8112, 0. 8866, and 0. 9496 respective to top 1, 3, 5, and 10. | arxiv:2205.05940 |
the present state of x - ray observations of cool stars in coeval open clusters is reviewed. concentrating on rosat results for solar - type stars, the available observational dataset is summarized along with those details of the evolution of x - ray activity of low mass stars which have been firmly established as a result. observational questions which are as yet unresolved are then addressed, including the origin of ` ` supersaturation ' ' and whether observations of one cluster can represent the x - ray properties of all clusters at the same age. the role of high spatial resolution x - ray imaging as a tool for identifying cluster members is highlighted and the prospects for future developments with axaf and xmm are discussed. | arxiv:astro-ph/9810009 |
owing to its charge - free property, magnon is highly promising to achieve dissipationless transport without joule heating and thus potentially applicable to energy - efficient devices. moreover, a kagome lattice, as stacking layers of many magnon ferromagnets, also exhibits valley structure in quasiparticle spectra, which are likely to add a new dimension to magnon excitation. here, we investigate valley magnon and associated valley modulation in a kagome lattice, with staggered exchange interaction and dzyaloshinskii - moriya interaction. the staggered exchange interaction breaks spatial inversion symmetry, leading to gapped degenerate valleys at $ \ pm k $ and consequent valley magnon hall effect. when the dzyaloshinskii - moriya interaction is further included, the valley degeneracy is lifted. as a result, net magnon anomalous hall effect and topological phase transition are realized. more interestingly, by tuning valley splitting and excitation frequency, heat currents in the kagome strip can be localized at one edge to achieve single - edge transport. besides, for the kagmon lattice, the edge heat currents include local circulating contribution within triangular fine structure, together with currents flowing parallel to the edges. these findings give full play to spin and valley degrees of freedom and enrich energy - efficient magnonic device paradigms. | arxiv:2010.09945 |
we introduce a pipeline to address anatomical inaccuracies in stable diffusion generated hand images. the initial step involves constructing a specialized dataset, focusing on hand anomalies, to train our models effectively. a finetuned detection model is pivotal for precise identification of these anomalies, ensuring targeted correction. body pose estimation aids in understanding hand orientation and positioning, crucial for accurate anomaly correction. the integration of controlnet and instructpix2pix facilitates sophisticated inpainting and pixel - level transformation, respectively. this dual approach allows for high - fidelity image adjustments. this comprehensive approach ensures the generation of images with anatomically accurate hands, closely resembling real - world appearances. our experimental results demonstrate the pipeline ' s efficacy in enhancing hand image realism in stable diffusion outputs. we provide an online demo at https : / / fixhand. yiqun. io | arxiv:2312.04236 |
acronym identification focuses on finding the acronyms and the phrases that have been abbreviated, which is crucial for scientific document understanding tasks. however, the limited size of manually annotated datasets hinders further improvement for the problem. recent breakthroughs of language models pre - trained on large corpora clearly show that unsupervised pre - training can vastly improve the performance of downstream tasks. in this paper, we present an adversarial training bert method named at - bert, our winning solution to acronym identification task for scientific document understanding ( sdu ) challenge of aaai 2021. specifically, the pre - trained bert is adopted to capture better semantic representation. then we incorporate the fgm adversarial training strategy into the fine - tuning of bert, which makes the model more robust and generalized. furthermore, an ensemble mechanism is devised to involve the representations learned from multiple bert variants. assembling all these components together, the experimental results on the sciai dataset show that our proposed approach outperforms all other competitive state - of - the - art methods. | arxiv:2101.03700 |
it is pointed out that the gravitational particle production rate of a scalar component of a chiral superfield in supergravity with minimal kahler potential can be significantly suppressed compared with a minimal scalar field in non - supersymmetric einstein gravity. this suppression is avoided for some choice of the inflaton sector and also for non - minimal kahler potential of the chiral superfield. | arxiv:1905.09143 |
we derive the effective dimensionally reduced schr \ " odinger equation with spin - orbit interaction in low - dimensional electronic strain driven nanostructures. a method of adiabatic separation among fast normal quantum degrees of freedom and slow tangential quantum degrees of freedom is used to show the emergence of a strain - induced rashba - like spin - orbit interaction ( soi ). by applying this analysis to one - dimensional curved quantum wires we demonstrate that the curvature - induced rashba soi leads to enhanced spin - orbit effects. | arxiv:1308.6190 |
we present a study of anonymized data capturing a month of high - level communication activities within the whole of the microsoft messenger instant - messaging system. we examine characteristics and patterns that emerge from the collective dynamics of large numbers of people, rather than the actions and characteristics of individuals. the dataset contains summary properties of 30 billion conversations among 240 million people. from the data, we construct a communication graph with 180 million nodes and 1. 3 billion undirected edges, creating the largest social network constructed and analyzed to date. we report on multiple aspects of the dataset and synthesized graph. we find that the graph is well - connected and robust to node removal. we investigate on a planetary - scale the oft - cited report that people are separated by ` ` six degrees of separation ' ' and find that the average path length among messenger users is 6. 6. we also find that people tend to communicate more with each other when they have similar age, language, and location, and that cross - gender conversations are both more frequent and of longer duration than conversations with the same gender. | arxiv:0803.0939 |
we study the ambient lipschitz geometry of semialgebraic surfaces. it was discovered in \ cite { bbg } that ambient lipschitz geometry is different from the outer lipschtz geometry. we show that two surface germs in $ \ mathbb { r } ^ 3 $, lipschitz normally embedded and with isolated singularity, are ambient bi - lipschitz equivalent if, and only if, they are outer bi - lipschitz equivalent and ambient topologically equivalent. | arxiv:2311.18570 |
the dynamic susceptibility of propylene carbonate in the moderately viscous regime above $ t _ { \ rm c } $ is reinvestigated by incoherent neutron and depolarised light scattering, and compared to dielectric loss and solvation response. depending on the strength of $ \ alpha $ relaxation, a more or less extended $ \ beta $ scaling regime is found. mode - coupling fits yield consistently $ \ lambda = 0. 72 $ and $ t _ { \ rm c } = 182 $ k, although different positions of the susceptibility minimum indicate that not all observables have reached the universal asymptotics. | arxiv:cond-mat/9908476 |
natural language processing ( nlp ) has been traditionally applied to medicine, and generative large language models ( llms ) have become prominent recently. however, the differences between them across different medical tasks remain underexplored. we analyzed 19, 123 studies, finding that generative llms demonstrate advantages in open - ended tasks, while traditional nlp dominates in information extraction and analysis tasks. as these technologies advance, ethical use of them is essential to ensure their potential in medical applications. | arxiv:2505.10261 |
making use of recently released data on dihadron correlations by the star collaboration, i analyze the long - range ( " ridge - like " ) part of these data and show that the dependence on both transverse momentum as well as orientation with respect to the event plane are consistent with correlations expected from only collective flow. in combination with previously analyzed centrality - dependent data, they provide strong evidence that only collective flow effects are present at large relative pseudorapidy. in contrast, by analyzing a " background subtracted " signal, the authors presenting the new data concluded that the ridge - like part of the measured correlation could not in fact be entirely generated from collective flow of the medium. i explain the discrepancy and illustrate some pitfalls of using the zyam prescription to remove flow background. | arxiv:1011.5773 |
pointer generator networks have been used successfully for abstractive summarization. along with the capability to generate novel words, it also allows the model to copy from the input text to handle out - of - vocabulary words. in this paper, we point out two key shortcomings of the summaries generated with this framework via manual inspection, statistical analysis and human evaluation. the first shortcoming is the extractive nature of the generated summaries, since the network eventually learns to copy from the input article most of the times, affecting the abstractive nature of the generated summaries. the second shortcoming is the factual inaccuracies in the generated text despite grammatical correctness. our analysis indicates that this arises due to incorrect attention transition between different parts of the article. we propose an initial attempt towards addressing both these shortcomings by externally appending traditional linguistic information parsed from the input text, thereby teaching networks on the structure of the underlying text. results indicate feasibility and potential of such additional cues for improved generation. | arxiv:1901.11492 |
intensified charge coupled device ( iccd ) cameras are widely used in various applications such as microscopy, astronomy, spectroscopy. often they are used as single - photon detectors, with thresholding being an essential part of the readout. in this paper, we measure the quantum efficiency of an iccd camera in the single - photon detection mode using the klyshko absolute calibration technique. the quantum efficiency is obtained as a function of the threshold value and of the wavelength of the detected light. in addition, we study the homogeneity of the photon sensitivity over the camera chip area. the experiment is performed in the autonomous regime, without using any additional detectors. we therefore demonstrate the self - calibration of an iccd camera. | arxiv:1607.07337 |
motivated by the inherent value of packets arising in many cyber - physical applications ( e. g., due to precision of the information content or an alarm message ), we consider status update systems with update packets carrying values as well as their generation time stamps. once generated, a status update packet has a random initial value and a deterministic deadline after which it is not useful ( ultimate staleness ). in our model, value of a packet decreases in time ( even after reception ) starting from its generation to ultimate staleness when it vanishes. the value of information ( voi ) at the receiver is additive in that the voi is the sum of the current values of all packets held by the receiver. we investigate various queuing disciplines under potential dependence between value and service time and provide closed form expressions for average voi at the receiver. numerical results illustrate the average voi for different scenarios and the contrast between average age of information ( aoi ) and average voi. | arxiv:2003.14069 |
we investigate the invariance of the gibbs measure for the fractional schrodinger equation of exponential type ( expnls ) $ i \ partial _ t u + ( - \ delta ) ^ { \ frac { \ alpha } 2 } u = 2 \ gamma \ beta e ^ { \ beta | u | ^ 2 } u $ on $ d $ - dimensional compact riemannian manifolds $ \ mathcal { m } $, for a dispersion parameter $ \ alpha > d $, some coupling constant $ \ beta > 0 $, and $ \ gamma \ neq 0 $. ( i ) we first study the construction of the gibbs measure for ( expnls ). we prove that in the defocusing case $ \ gamma > 0 $, the measure is well - defined in the whole regime $ \ alpha > d $ and $ \ beta > 0 $ ( theorem 1. 1 ( i ) ), while in the focusing case $ \ gamma < 0 $ its partition function is always infinite for any $ \ alpha > d $ and $ \ beta > 0 $, even with a mass cut - off of arbitrary small size ( theorem 1. 1 ( ii ) ). ( ii ) we then study the dynamics ( expnls ) with random initial data of low regularity. we first use a compactness argument to prove weak invariance of the gibbs measure in the whole regime $ \ alpha > d $ and $ 0 < \ beta < \ beta ^ \ star _ \ alpha $ for some natural parameter $ 0 < \ beta ^ \ star _ \ alpha \ sim ( \ alpha - d ) $ ( theorem 1. 3 ( i ) ). in the large dispersion regime $ \ alpha > 2d $, we can improve this result by constructing a local deterministic flow for ( expnls ) for any $ \ beta > 0 $. using the gibbs measure, we prove that solutions are almost surely global for $ 0 < \ beta \ ll \ beta ^ \ star _ \ alpha $, and that the gibbs measure is invariant ( theorem 1. 3 ( ii ) ). ( iii ) finally, in the particular case $ d = 1 $ and $ \ mathcal { m } = \ mathbb { t } $, we are able to exploit some probabilistic multilinear smoothing effects to build a probabilistic flow for ( expnls ) for $ 1 + \ frac { \ sqrt | arxiv:2104.14348 |
an rna - seq experiment with 48 biological replicates in each of 2 conditions was performed to determine the number of biological replicates ( $ n _ r $ ) required, and to identify the most effective statistical analysis tools for identifying differential gene expression ( dge ). when $ n _ r = 3 $, seven of the nine tools evaluated give true positive rates ( tpr ) of only 20 to 40 percent. for high fold - change genes ( $ | log _ { 2 } ( fc ) | \ gt2 $ ) the tpr is $ \ gt85 $ percent. two tools performed poorly ; over - or under - predicting the number of differentially expressed genes. increasing replication gives a large increase in tpr when considering all de genes but only a small increase for high fold - change genes. achieving a tpr $ \ gt85 $ % across all fold - changes requires $ n _ r \ gt20 $. for future rna - seq experiments these results suggest $ n _ r \ gt6 $, rising to $ n _ r \ gt12 $ when identifying dge irrespective of fold - change is important. for $ 6 \ lt n _ r \ lt 12 $, superior tpr makes edger the leading tool tested. for $ n _ r \ ge12 $, minimizing false positives is more important and deseq outperforms the other tools. | arxiv:1505.02017 |
we prove various estimates for the first eigenvalue of the magnetic dirichlet laplacian on a bounded domain in two dimensions. when the magnetic field is constant, we give lower and upper bounds in terms of geometric quantities of the domain. we furthermore prove a lower bound for the first magnetic neumann eigenvalue in the case of constant field. | arxiv:1501.05554 |
the success and superior performance of deep networks is spreading their popularity and use to an increasing number of applications. very recent works, however, demonstrate that modern day deep networks suffer from irreproducibility ( also referred to as nondeterminism or underspecification ). two or more models that are identical in architecture, structure, training hyper - parameters, and parameters, and that are trained on exactly the same training data, yield different predictions on individual previously unseen examples. thus, a model that performs well on controlled test data, may perform in unexpected ways when deployed in the real world, whose data is expected to be similar to the test data. we study simple synthetic models and data to understand the origins of these problems. we show that even with a single nonlinearity and for very simple data and models, irreproducibility occurs. our study demonstrates the effects of randomness in initialization, training data shuffling window size, and activation functions on prediction irreproducibility, even under very controlled synthetic data. while, as one would expect, randomness in initialization and in shuffling the training examples exacerbates the phenomenon, we show that model complexity and the choice of nonlinearity also play significant roles in making deep models irreproducible. | arxiv:2102.10696 |
we present a quantitative benchmark of multiscale models for dendritic growth simulations. we focus on approaches based on phase - field, dendritic needle network, and grain envelope dynamics. as a first step, we focus on isothermal growth of an equiaxed grain in a supersaturated liquid in three dimensions. a quantitative phase - field formulation for solidification of a dilute binary alloy is used as the reference benchmark. we study the effect of numerical and modeling parameters in both needle - based and envelope - based approaches, in terms of their capacity to quantitatively reproduce phase - field reference results. in light of this benchmark, we discuss the capabilities and limitations of each approach in quantitatively and efficiently predicting transient and steady states of dendritic growth. we identify parameters that yield a good compromise between accuracy and computational efficiency in both needle - based and envelope - based models. we expect that these results will guide further developments and utilization of these models, and ultimately pave the way to a quantitative bridging of the dendrite tip scale with that of entire experiments and solidification processes. | arxiv:2003.05250 |
later. in january 2009, the firm generated internet buzz with a mysterious website promising a " stem cell - like " processor which would give a 100 - fold increase in supercomputing power over current technology, as well as advances in consumer 3d graphics. at ces 2009, it was revealed to be the zms - 05 processor from ziilabs, a subsidiary formed from the combining of 3dlabs and creative ' s personal digital entertainment division. = = = 2012 – present = = = in november 2012, the firm announced it has entered into an agreement with intel corporation for intel to license technology and patents from ziilabs inc. ltd, a wholly owned subsidiary of creative, and acquire engineering resources and assets related to its uk branch as a part of a $ 50 million deal. ziilabs ( still wholly owned by creative ) continues to retain all ownership of its stemcell media processor technologies and patents, and will continue to supply and support its zms series of chips to its customers. from 2014 to 2017, creative ' s revenue from audio products have contracted at an average of 15 % annually, due to increased competition in the audio space. at the consumer electronics show ( ces ) in las vegas in january 2018, its super x - fi dongle won the best of ces 2018 award by avs forum. the product was launched after more than $ 100 million in investment and garnered positive analyst reports. this new technology renewed interest in the company and likely helped to raise its share price from s $ 1. 25 to s $ 8. 75 within a 2 - week period. the company is still producing chinese - language and bilingual software for the singapore market, but nearly half of the company ' s income is generated in the united states and south america ; the european union represents 32 % of revenues, with asia making the remainder. on january 4, 2023, sim died at age 67, with president of creative labs business unit song siow hui appointed as interim ceo. on 16 may 2025, it was announced that freddy sim, brother of sim wong hoo, was appointed as the new ceo with the interim ceo, dr tan jok tin, remaining executive chairman. = = products = = = = = sound blaster = = = creative ' s sound blaster sound card was among the first dedicated audio processing cards to be made widely available to the general consumer. as the first to bundle what is now considered to be a part of a sound card system : digital audio, on - board music synthesizer | https://en.wikipedia.org/wiki/Creative_Technology |
an important problem in training deep networks with high capacity is to ensure that the trained network works well when presented with new inputs outside the training dataset. dropout is an effective regularization technique to boost the network generalization in which a random subset of the elements of the given data and the extracted features are set to zero during the training process. in this paper, a new randomized regularization technique in which we withhold a random part of the data without necessarily turning off the neurons / data - elements is proposed. in the proposed method, of which the conventional dropout is shown to be a special case, random data dropout is performed in an arbitrary basis, hence the designation generalized dropout. we also present a framework whereby the proposed technique can be applied efficiently to convolutional neural networks. the presented numerical experiments demonstrate that the proposed technique yields notable performance gain. generalized dropout provides new insight into the idea of dropout, shows that we can achieve different performance gains by using different bases matrices, and opens up a new research question as of how to choose optimal bases matrices that achieve maximal performance gain. | arxiv:1712.00891 |
in this short note we would like to show how it is possible to use techniques introduced in the theory of local dynamics of holomorphic germs tangent to the identity to study global meromorphic self - maps of the complex projective space. in particular we shall show how a meromorphic self - map of a complex projective space induces a holomorphic foliation of the projective space in riemann surfaces, whose singular points are exactly the fixed points and the indeterminacy points of the map ; and we shall prove three index theorems, relating suitably defined local residues at the fixed and indeterminacy points with chern classes of the projective space. | arxiv:1106.2394 |
mfix - exa is a new code being actively developed at lawrence berkeley national laboratory and the national energy technology laboratory as part of the u. s. department of energy ' s exascale computing project. the starting point for the mfix - exa code development was the extraction of basic computational fluid dynamic ( cfd ) and discrete element method ( dem ) capabilities from the existing mfix - dem code which was refactored into an amrex code architecture, herein referred to as the preliminary mfix - exa code. although drastic changes to the codebase will be required to produce an exascale capable application, benchmarking of the originating code helps to establish a valid start point for future development. in this work, four benchmark cases are considered, each corresponding to experimental data sets with history of cfd - dem validation. we find that the preliminary mfix - exa code compares favorably with classic mfix - dem simulation predictions for three slugging / bubbling fluidized beds and one spout - fluid bed. comparison to experimental data is also acceptable ( within accuracy expected from previous cfd - dem benchmarking and validation exercises ) which is comprised of several measurement techniques including particle tracking velocimetry, positron emission particle tracking and magnetic resonance imaging. the work concludes with an overview of planned developmental work and potential benchmark cases to validate new mfix - exa capabilities. | arxiv:1909.02067 |
sickle cell anemia, which is characterized by abnormal erythrocyte morphology, can be detected using microscopic images. computational techniques in medicine enhance the diagnosis and treatment efficiency. however, many computational techniques, particularly those based on convolutional neural networks ( cnns ), require high resources and time for training, highlighting the research opportunities in methods with low computational overhead. in this paper, we propose a novel approach combining conventional classifiers, segmented images, and cnns for the automated classification of sickle cell disease. we evaluated the impact of segmented images on classification, providing insight into deep learning integration. our results demonstrate that using segmented images and cnn features with an svm achieves an accuracy of 96. 80 %. this finding is relevant for computationally efficient scenarios, paving the way for future research and advancements in medical - image analysis. | arxiv:2412.17975 |
this paper presents data on the optical thickness aot in the context of long - term observations, including in times of large - scale forest fires in yakutia. sudden changes in such features as the aot point directly to the impact of fires on aerosol structure of the atmosphere during the summer. | arxiv:1612.08610 |
dichotomy theorems, which characterize the conditions under which a problem can be solved efficiently, have helped identify important tractability borders for as probabilistic query evaluation, view maintenance, query containment ( among many more problems ). however, dichotomy theorems for many such problems remain elusive under key settings such as bag semantics or for queries with self - joins. this work aims to unearth dichotomies for fundamental problems in reverse data management and knowledge representation. we use a novel approach to discovering dichotomies : instead of creating dedicated algorithms for easy ( ptime ) and hard cases ( np - complete ), we devise unified algorithms that are guaranteed to terminate in ptime for easy cases. using this approach, we discovered new tractable cases for the problem of minimal factorization of provenance formulas as well as dichotomies under bag semantics for the problems of resilience and causal responsibility | arxiv:2308.13172 |
we present a novel control strategy for a team of unmanned aerial vehicles ( uavs ) to autonomously achieve a desired formation using only visual feedback provided by the uav ' s onboard cameras. this effectively eliminates the need for global position measurements. the proposed pipeline is fully distributed and encompasses a collision avoidance scheme. in our approach, each uav extracts feature points from captured images and communicates their pixel coordinates and descriptors among its neighbors. these feature points are used in our novel pose estimation algorithm, quest, to localize the neighboring uavs. compared to existing methods, quest has better estimation accuracy and is robust to feature point degeneracies. we demonstrate the proposed pipeline in a high - fidelity simulation environment and show that uavs can achieve a desired formation in a natural environment without any fiducial markers. | arxiv:1809.00096 |
we present korea microlensing telescope network ( kmtnet ) light curves for microlensing - event candidates in the kepler k2 c9 field having peaks within 3 effective timescales of the kepler observations. these include 181 " clear microlensing " and 84 " possible microlensing " events found by the kmtnet event finder, plus 56 other events found by ogle and / or moa that were not found by kmtnet. all data for the first two classes are immediately available for public use without restriction. | arxiv:1801.08166 |
room acoustics is mainly based on the reverberation theories of saine and eyring. in sabine ' s theory however, the reverberation time does not reach zero, even if the condition of absolute absorption is fulfilled. eyring revised reverberation theory to resolve this contradiction. however, eyring ' s theory has an inconsistency between the formulations of the steady - state and decay processes. therefore, the author revised sabine ' s theory, taking a different approach from that of eyring. this revised theory was constructed by introducing the concept of " reverberation of a direct sound. " in this study, a new mathematical model of reverberation using reflection orders is proposed. this is a reconstruction of the author ' s revised theory. the new model includes the temporal energy distribution in each reflection order and uses the concept of " reverberation of a direct sound " for the entire reverberation process. it shows that the concept is also essential for the reflected sounds. in addition, the reverberation decay agrees with the revised theory previously proposed by the author. overall, the new model showed good agreement with the simulation results. | arxiv:2408.11670 |
high - harmonic upconversion driven by a mid - infrared femtosecond laser can generate coherent soft x - ray beams in a tabletop - scale setup. here, we report on a compact ytterbium - pumped optical parametric chirped pulse amplifier ( opcpa ) laser system seeded by an all - fiber front - end and employing periodically - poled lithium niobate ( ppln ) nonlinear media operated near the pulse fluence limits of current commercially available ppln crystals. the opcpa delivers 3 $ \ mu $ m wavelength pulses with 775 $ \ mu $ j energy at 1 khz repetition rate, with transform - limited 120 fs pulse duration, diffraction - limited beam quality, and ultrahigh 0. 33 % rms energy stability over > 18 hours. using this laser, we generate soft x - ray high harmonics ( hhg ) in argon gas by focusing into a low - loss, high - pressure gas - filled anti - resonant hollow core fiber ( arhcf ), generating coherent light at photon energies up to the argon l - edge ( 250 ev ) and carbon k - edge ( 284 ev ), with high beam quality and ~ 1 % rms energy stability. this work demonstrates soft x - ray hhg in a high - efficiency guided - wave phase matched geometry, overcoming the high losses inherent to mid - ir propagation in unstructured waveguides, or the short interaction lengths of gas cells or jets. the arhcf can operate long term without damage, and with the repetition rate, stability and robustness required for demanding applications in spectro - microscopy and imaging. finally, we discuss routes for maximizing the soft x - ray hhg flux by driving he at higher laser intensities using either 1. 5 $ \ mu $ m or 3 $ \ mu $ m - the signal and idler wavelengths of the laser. | arxiv:2504.01112 |
we report on the numerical discovery of quasi - periodic oscillations ( qpos ) associated with accretion through a non - axisymmetric magnetic boundary layer in the unstable regime, when two ordered equatorial streams form and rotate synchronously at approximately the angular velocity of the inner disk the streams hit the star ' s surface producing hot spots. rotation of the spots leads to high - frequency qpos. we performed a number of simulation runs for different magnetospheric sizes from small to tiny, and observed a definite correlation between the inner disk radius and the qpo frequency : the frequency is higher when the magnetosphere is smaller. in the stable regime a small magnetosphere forms and accretion through the usual funnel streams is observed, and the frequency of the star is expected to dominate the lightcurve. we performed exploratory investigations of the case in which the magnetosphere becomes negligibly small and the disk interacts with the star through an equatorial belt. we also performed investigation of somewhat larger magnetospheres where one or two ordered tongues may dominate over other chaotic tongues. in application to millisecond pulsars we obtain qpo frequencies in the range of 350 hz to 990 hz for one spot. the frequency associated with rotation of one spot may dominate if spots are not identical or antipodal. if the spots are similar and antipodal then the frequencies are twice as high. we show that variation of the accretion rate leads to drift of the qpo peak. | arxiv:0812.0384 |
we investigate a cosmological model in which a fraction of the dark matter is atomic dark matter ( adm ). this adm consists of dark versions of the electron and of the proton, interacting with each other and with dark photons just as their light sector versions do, but interacting with everything else only gravitationally. we find constraints given current cosmic microwave background ( cmb ) and baryon acoustic oscillation ( bao ) data, with and without an $ h _ 0 $ prior, and with and without enforcing a big bang nucleosynthesis consistent helium abundance. we find that, at low dark photon temperature, one can have consistency with bao and cmb data, with a fraction of dark matter that is adm ( $ f _ { \ rm adm } $ ) as large as $ \ sim 0. 1 $. such a large $ f _ { \ rm adm } $ leads to a suppression of density fluctuations today on scales below about 60 mpc that may be of relevance to the $ \ sigma _ 8 $ tension. our work motivates calculation of nonlinear corrections to matter power spectrum predictions in the adm model. we forecast parameter constraints to come from future ground - based cmb surveys, and find that if adm is indeed the cause of the $ \ sigma _ 8 $ tension, the influence of the adm, primarily on cmb lensing, will likely be detectable at high significance. | arxiv:2311.05678 |
simon et al suggest that composite fermions ( cf ) must be replaced by composite bosons ( cb ) and " 111 " state is a boson state. however, we find that such a transition in real gaas is not possible and cf state cannot become a boson. simon et al suggest that the total number of cf and cb is conserved. however, we find that the number of quasiparticles need not be conserved. similarly, simon et al suggest that cfs are formed but we find that this formation does not conserve energy so that cfs will not be formed. simon et al compute using products of fermion and boson wave functions. we find that the mass of the cf is much too larger than experimental mass. we find that these computed results are not in agreement with the data. | arxiv:cond-mat/0302009 |
the 21 cm brightness temperature $ \ delta t _ { \ rm b } $ fluctuations from reionization promise to provide information on the physical processes during that epoch. we present a formalism for generating the $ \ delta t _ { \ rm b } $ distribution using dark matter simulations and an one - dimensional radiative transfer code. our analysis is able to account for the spin temperature $ t _ { \ rm s } $ fluctuations arising from inhomogeneous x - ray heating and ly $ \ alpha $ coupling during cosmic dawn. the $ \ delta t _ { \ rm b } $ power spectrum amplitude at large scales ( $ k \ sim 0. 1 $ mpc $ ^ { - 1 } $ ) is maximum when $ \ sim 10 \ % $ of the gas ( by volume ) is heated above the cmb temperature. the power spectrum shows a " bump " - like feature during cosmic dawn and its location measures the typical sizes of heated regions. we find that the effect of peculiar velocities on the power spectrum is negligible at large scales for most part of the reionization history. during early stages ( when the volume averaged ionization fraction $ \ lesssim 0. 2 $ ) this is because the signal is dominated by fluctuations in $ t _ { \ rm s } $. for reionization models that are solely driven by stars within high mass ( $ \ gtrsim 10 ^ 9 \, \ rm m _ { \ odot } $ ) haloes, the peculiar velocity effects are prominent only at smaller scales ( $ k \ gtrsim 0. 4 $ mpc $ ^ { - 1 } $ ) where patchiness in the neutral hydrogen density dominates the signal. the conclusions are unaffected by changes in the amplitude or steepness in the x - ray spectra of the sources. | arxiv:1406.4157 |
from the pioneering work of winter [ phys. rev. 124, 452 ( 1961 ) ], a magnetic domain wall of bloch type is known to host a special wall - bound spin - wave mode, which corresponds to spin - waves being channeled along the magnetic texture. using micromagnetic simulations, we investigate spin - waves travelling inside bloch walls formed in thin magnetic media with perpendicular - to - plane magnetic anisotropy and we show that their propagation is actually strongly nonreciprocal, as a result of dynamic dipolar interactions. we investigate spin - wave non - reciprocity effects in single bloch walls, which allows us to clearly pinpoint their origin, as well as in arrays of parallel walls in stripe domain configurations. for such arrays, a complex domain - wall - bound spin - wave band structure develops, some aspects of which can be understood qualitatively from the single - wall picture by considering that a wall array consists of a sequence of up / down and down / up walls with opposite non - reciprocities. circumstances are identified in which the non - reciprocity is so extreme that spin - wave propagation inside individual walls becomes unidirectional. | arxiv:1812.08741 |
the babar detector, operating at energies near the $ \ upsilon ( 4s ) $ resonance at the pep - ii asymmetric $ b $ factory at slac, has collected a sample of 32 million $ b \ bar b $ pairs by may 2001. a study of time - dependent cp - violating asymmetries in events where one neutral $ b $ meson is fully reconstructed in a final state containing charmonium has resulted in the measurement $ \ sin2 \ beta = 0. 59 \ pm 0. 14 { \ rm ( stat ) } \ pm 0. 05 { \ rm ( syst ) } $, which establishes cp violation in the $ b ^ 0 $ meson system at the 4 $ \ sigma $ level. $ b $ lifetime and mixing measurements from a sub - sample of 23 million $ b \ bar b $ pairs are also presented. | arxiv:hep-ex/0110064 |
results of a careful analysis of the highly ionized absorption systems, observed over the redshift range 2. 198 - - 2. 2215 in the zem = 2. 24 hdfs - qso j2233 - 606, are presented. strong ovi and neviii absorptions are detected. most of the lines show signature of partial coverage which varies from species to species. this can be understood if the clouds cover the continuum emission region completely and only a fraction of the broad emission line region. using photo - ionization models we analyze in more detail the component at zabs = 2. 198. absolute abundances are close to solar but the [ n / c ] abundance ratio is larger than solar. this result, which is consistent with the analysis of high - z qso broad emission - lines, confirms the physical association of the absorbing gas with the agn. the observed column densities of niv, nv and neviii favor a two - zone model for the absorbing region where neviii is predominantly produced in the highly ionized zone. it is most likely that in qso j2233 - 606, the region producing the neviii absorption can not be a warm absorber. one of the lyalpha absorption lines at zabs = 2. 2215 has a flat bottom typical of saturated lines and non - zero residual intensity in the core, consistent with partial coverage. there is no metal - line from this lyalpha cloud detectable in the spectrum which suggests either large chemical inhomogeneities in the gas or that the gas is very highly ionized. if the latter is true the cloud could have a total hydrogen column density consistent with that of x - ray absorbers. it is therefore of first importance to check whether or not there is an x - ray warm - absorber in front of this qso. | arxiv:astro-ph/9902070 |
we study $ a $ - hypergeometric systems $ h _ a ( \ beta ) $ in the sense of gelfand, kapranov and zelevinsky under two aspects : the structure of their holonomically dual system, and reducibility of their rank module. we prove first that rank - jumping parameters always correspond to reducible systems, and we show that the property of being reducible is ` ` invariant modulo the lattice ' '. in the second part we study a conjecture of nobuki takayama which states that the holonomic dual of $ h _ a ( \ beta ) $ is of the form $ h _ a ( \ beta ' ) $ for suitable $ \ beta ' $. we prove the conjecture for all matrices $ a $ and generic parameter $ \ beta $, exhibit an example that shows that in general the conjecture cannot hold, and present a refined version of the conjecture. questions on both duality and reducibility have been impossible to answer with classical methods. this paper may be seen as an example of the usefulness, and scope of applications, of the homological tools for $ a $ - hypergeometric systems developed in \ cite { mmw }. | arxiv:math/0508622 |
we present a study of the achievable rates for classical information transmission via a lossy bosonic channel with memory, using homodyne detection. a comparison with the memoryless case shows that the presence of memory enhances the bit rate if information is encoded in collective states, i. e. states which are entangled over different uses of the channel. | arxiv:0901.4966 |
we show that the higher dimensional weierstrass and ehrlich - aberth methods for finding roots of polynomials have infinite orbits that diverge to infinity. this is possible for the jacobi update scheme ( all coordinates are updated in parallel ) as well as gauss - seidel ( any coordinate update is used for all subsequent coordinates ). | arxiv:2011.01660 |
dynamic linear regression models forecast the values of a time series based on a linear combination of a set of exogenous time series while incorporating a time series process for the error term. this error process is often assumed to follow a stationary autoregressive integrated moving average ( arima ) model, or its seasonal variants, which is unable to capture a long - range dependence structure ( long memory ) of the error process. we propose a novel dynamic linear regression model that incorporates the long - range dependence feature of the errors and show that the proposed error process may : ( i ) have a significant impact on the posterior uncertainty of the estimated regression parameters and ( ii ) improve the model ' s forecasting ability. we develop a markov chain monte carlo method to fit general dynamic linear regression models based on a frequency domain approach that enables fast, asymptotically exact bayesian inference for large datasets. we demonstrate that our approximate algorithm is faster than the traditional time domain approaches, such as the kalman filter and the multivariate gaussian likelihood, while producing a highly accurate approximation to the posterior. the method is illustrated in simulated examples and two energy forecasting applications. | arxiv:2408.09096 |
we prove a sharp stability estimate for the problem of reconstructing a symmetric 2 - tensor from its integrals along all maximal geodesics on a simple manifold. | arxiv:0803.3958 |
in this paper, we have proposed a new glaucoma classification approach that employs a wavelet neural network ( wnn ) on optimally enhanced retinal images features. to avoid tedious and error prone manual analysis of retinal images by ophthalmologists, computer aided diagnosis ( cad ) substantially aids in robust diagnosis. our objective is to introduce a cad system with a fresh approach. retinal image quality improvement is attempted in two phases. the retinal image preprocessing phase improves the brightness and contrast of the image through quantile based histogram modification. it is followed by the image enhancement phase, which involves multi scale morphological operations using image specific dynamic structuring elements for the retinal structure enrichment. graph based retinal image features in terms of local graph structures ( lgs ) and graph shortest path ( gsp ) statistics are extracted from various directions along with the statistical features from the enhanced retinal dataset. wnn is employed to classify glaucoma retinal images with a suitable wavelet activation function. the performance of the wnn classifier is compared with multilayer perceptron neural networks with various datasets. the results show our approach is superior to the existing approaches. | arxiv:2206.12099 |
there are now thousands of single - planet systems observed to exhibit transit timing variations ( ttvs ), yet we largely lack any interpretation of the implied masses responsible for these perturbations. even when assuming these ttvs are driven by perturbing planets, the solution space is notoriously multi - modal with respect to the perturber ' s orbital period and there exists no standardized procedure to pinpoint these modes, besides from blind brute force numerical efforts. using $ n $ - body simulations with $ \ texttt { ttvfast } $ and focusing on the dominant periodic signal in the ttvs, we chart out the landscape of these modes and provide analytic predictions for their locations and widths, providing the community with a map for the first time. we then introduce an approach for modeling single - planet ttvs in the low - eccentricity regime, by splitting the orbital period space into a number of uniform prior bins over which there aren ' t these degeneracies. we show how one can define appropriate orbital period priors for the perturbing planet in order to sufficiently sample the complete parameter space. we demonstrate, analytically, how one can explain the numerical simulations using first - order near mean - motion resonance super - periods, the synodic period, and their aliases - - the expected dominant ttv periods in the low - eccentricity regime. using a bayesian framework, we then present a method for determining the optimal solution between ttvs induced by a perturbing planet and ttvs induced by a moon. | arxiv:2411.10493 |
the anomalous viscous fluid dynamics model, avfd, is used in concert with the charge - sensitive correlator $ r _ { \ psi _ 2 } ( \ delta s ) $ to investigate the scaling properties of background - and chiral - magnetically - driven ( cme ) charge separation ( $ \ delta s $ ), characterized by the inverse variance $ \ mathrm { \ sigma ^ { - 2 } _ { r _ { \ psi _ 2 } } } $ of the $ r _ { \ psi _ { 2 } } ( \ delta s ) $ distributions obtained in collisions at $ \ sqrt s _ { \ mathrm { nn } } = 200 $ gev. the $ \ mathrm { \ sigma ^ { - 2 } _ { r _ { \ psi _ 2 } } } $ values for the background are observed to be event - shape - independent. however, they scale with the reciprocal charged - particle multiplicity $ ( 1 / \ left < n _ { \ rm ch } \ right > ) $, indicating an essential constraint for discerning background from the signal and a robust estimate of the difference between the backgrounds in ru + ru and zr + zr collisions. by contrast, the $ \ mathrm { \ sigma ^ { - 2 } _ { r _ { \ psi _ 2 } } } $ values for signal + background show characteristic $ 1 / \ left < n _ { \ rm ch } \ right > $ scaling violations that characterize the cme - driven contributions. corrections to recent $ { r _ { \ psi _ 2 } ( \ delta s ) } $ measurements \ cite { star : 2021mii } that account for the background difference in ru + ru and zr + zr collisions indicate a charge separation difference compatible with the cme. the results further suggest that $ \ mathrm { \ sigma ^ { - 2 } _ { r _ { \ psi _ 2 } } } $ measurements for peripheral and central collisions in concert with $ 1 / \ left < n _ { \ rm ch } \ right > $ scaling, provides a robust constraint to quantify the background and aid characterization of the cme. | arxiv:2203.10029 |
this thesis is a compendium of research which brings together ideas from the fields of complex networks and computational neuroscience to address two questions regarding neural systems : 1 ) how the activity of neurons, via synaptic changes, can shape the topology of the network they form part of, and 2 ) how the resulting network structure, in its turn, might condition aspects of brain behaviour. although the emphasis is on neural networks, several theoretical findings which are relevant for complex networks in general are presented - - such as a method for studying network evolution as a stochastic process, or a theory that allows for ensembles of correlated networks, and sets of dynamical elements thereon, to be treated mathematically and computationally in a model - independent manner. some of the results are used to explain experimental data - - certain properties of brain tissue, the spontaneous emergence of correlations in all kinds of networks... - - and predictions regarding statistical aspects of the central nervous system are made. the mechanism of cluster reverberation is proposed to account for the near - instant storage of novel information the brain is capable of. | arxiv:1302.3943 |
we investigate the centrality dependence of the pt - correlations in the event - by - event analysis of relativistic heavy - ion collisions at rhic made recently by the phenix and star collaborations. we notice that sigma ^ 2 dynamical scales to a very good accuracy with the inverse number of the produced particles, n. this scaling can be naturally explained by formation of clusters. we discuss the nature of clusters and provide numerical estimates of correlations coming from resonance decays, which are tiny, and a model where particle are emitted from local thermalized sources moving at the same collective velocity. this " lumped cluster " model can explain the data when on the average 6 - 15 particles are contained in a cluster. we also point out simple relations of the popular correlation measures to the covariance, which arise under the assumptions ( well holding at rhic ) that the distributions are sharply peaked in n and that the dynamical compared to statistical fluctuations are small. | arxiv:nucl-th/0611069 |
entanglement detection in high dimensional systems is a np - hard problem since it is lacking an efficient way. given a bipartite quantum state of interest free entanglement can be detected efficiently by the ppt - criterion ( peres - horodecki criterion ), in contrast to detecting bound entanglement, i. e. a curious form of entanglement that can also not be distilled into maximally ( free ) entangled states. only a few bound entangled states have been found, typically by constructing dedicated entanglement witnesses, so naturally the question arises how large is the volume of those states. we define a large family of magically symmetric states of bipartite qutrits for which we find $ 82 \ % $ to be free entangled, $ 2 \ % $ to be certainly separable and as much as $ 10 \ % $ to be bound entangled, which shows that this kind of entanglement is not rare. via various machine learning algorithms we can confirm that the remaining $ 6 \ % $ of states are more likely to belonging to the set of separable states than bound entangled states. most important we find via dimension reduction algorithms that there is a strong $ 2 $ - dimensional ( linear ) sub - structure in the set of bound entangled states. this revealed structure opens a novel path to find and characterize bound entanglement towards solving the long - standing problem of what the existence of bound entanglement is implying. | arxiv:2106.03977 |
recently, an idling mechanism has been introduced in the context of distributed \ emph { first order } methods for minimization of a sum of nodes ' local convex costs over a generic, connected network. with the idling mechanism, each node $ i $, at each iteration $ k $, is active - - updates its solution estimate and exchanges messages with its network neighborhood - - with probability $ p _ k $, and it stays idle with probability $ 1 - p _ k $, while the activations are independent both across nodes and across iterations. in this paper, we demonstrate that the idling mechanism can be successfully incorporated in \ emph { distributed second order methods } also. specifically, we apply the idling mechanism to the recently proposed distributed quasi newton method ( dqn ). we first show theoretically that, when $ p _ k $ grows to one across iterations in a controlled manner, dqn with idling exhibits very similar theoretical convergence and convergence rates properties as the standard dqn method, thus achieving the same order of convergence rate ( r - linear ) as the standard dqn, but with significantly cheaper updates. simulation examples confirm the benefits of incorporating the idling mechanism, demonstrate the method ' s flexibility with respect to the choice of the $ p _ k $ ' s, and compare the proposed idling method with related algorithms from the literature. | arxiv:1709.01307 |
in the framework of loop quantum cosmology, particularly within the quantum oppenheimer - snyder model, the semiclassical ashtekar - pawlowski - singh ( aps ) metric is associated with a static, spherically symmetric black hole that incorporates quantum effects derived from the aps metric. this quantum - corrected black hole can be interpreted as a modified schwarzschild black hole, where the schwarzschild metric function is adjusted by an additional term proportional to $ \ frac { m ^ { 2 } } { r ^ { 4 } } $, with $ r $ denoting the radial coordinate and $ m, $ the black hole mass. in this study, we show that such a quantum - mechanically modified black hole can arise in the context of nonlinear electrodynamics with either electric or magnetic charge. this charged, quantum - corrected solution is then matched to a dust ball of constant mass $ m _ { aps } $, governed by the aps metric, at a timelike thin - shell possessing nonzero mass $ m $ and electric charge $ q $ or magnetic charge $ p $. analytically, it is demonstrated that the thin - shell oscillates around an equilibrium radius $ r = r _ { eq } $, which is expressed in terms of $ % m _ { aps } $, $ m $, and $ q $ or $ p $. | arxiv:2502.10457 |
let $ h $ be the planar gaussian free field and let $ d _ h $ be a supercritical liouville quantum gravity ( lqg ) metric associated with $ h $. such metrics arise as subsequential scaling limits of supercritical liouville first passage percolation ( ding - gwynne, 2020 ) and correspond to values of the matter central charge $ \ mathbf { c } _ { \ mathrm m } \ in ( 1, 25 ) $. we show that a. s. the boundary of each complementary connected component of a $ d _ h $ - metric ball is a jordan curve and is compact and finite - dimensional with respect to $ d _ h $. this is in contrast to the \ emph { whole } boundary of the $ d _ h $ - metric ball, which is non - compact and infinite - dimensional with respect to $ d _ h $ ( pfeffer, 2021 ). using our regularity results for boundaries of complementary connected components of $ d _ h $ - metric balls, we extend the confluence of geodesics results of gwynne - miller ( 2019 ) to the case of supercritical liouville quantum gravity. these results show that two $ d _ h $ - geodesics with the same starting point and different target points coincide for a non - trivial initial time interval. | arxiv:2104.06502 |
we investigate a superradiating system coupled to external reservoirs. under conditions where electrons tunneling at a rate $ t $ act like an electron pump, we predict a novel phenomenon in the form of oscillations with a frequency $ \ omega \ simeq \ sqrt { 2 \ gamma t } $ that appear in the ( photon ) emission intensity, where $ \ gamma $ is the spontaneous decay rate of a single two - level system. the effect, together with a strong enhancement of the superradiant peak, should be observable in semiconductor quantum wells in strong magnetic fields, or in quantum dot arrays. | arxiv:cond-mat/9803133 |
game level blending via machine learning, the process of combining features of game levels to create unique and novel game levels using procedural content generation via machine learning ( pcgml ) techniques, has gained increasing popularity in recent years. however, many existing techniques rely on human - annotated level representations, which limits game level blending to a limited number of annotated games. even with annotated games, researchers often need to author an additional shared representation to make blending possible. in this paper, we present a novel approach to game level blending that employs clustering - based tile embeddings ( cte ), a learned level representation technique that can serve as a level representation for unannotated games and a unified level representation across games without the need for human annotation. cte represents game level tiles as a continuous vector representation, unifying their visual, contextual, and behavioral information. we apply this approach to two classic nintendo games, lode runner and the legend of zelda. we run an evaluation comparing the cte representation to a common, human - annotated representation in the blending task and find that cte has comparable or better performance without the need for human annotation. | arxiv:2306.16666 |
1 - 3 per cent of white dwarfs are orbited by planetary dusty debris detectable as infrared emission in excess above the white dwarf flux. in a rare subset of these systems, a gaseous disc component is also detected via emission lines of the ca ii 8600 \ r { a } triplet, broadened by the keplerian velocity of the disc. we present the first statistical study of the fraction of debris discs containing detectable amounts of gas in emission at white dwarfs within a magnitude and signal - to - noise limited sample. we select 7705 single white dwarfs spectroscopically observed by the sloan digital sky survey ( sdss ) and $ gaia $ with magnitudes $ g $ $ \ leq $ 19. we identify five gaseous disc hosts, all of which have been previously discovered. we calculate the occurrence rate of a white dwarf hosting a debris disc detectable via ca ii emission lines as 0. 067 $ \ pm $ $ _ { 0. 025 } ^ { 0. 042 } $ per cent. this corresponds to an occurrence rate for a dusty debris disc to have an observable gaseous component in emission as 4 $ \ pm $ $ _ { 2 } ^ { 4 } $ per cent. given that variability is a common feature of the emission profiles of gaseous debris discs, and the recent detection of a planetesimal orbiting within the disc of sdssj122859. 93 + 104032. 9, we propose that gaseous components are tracers for the presence of planetesimals embedded in the discs and outline a qualitative model. we also present spectroscopy of the ca ii triplet 8600 \ r { a } region for 20 white dwarfs hosting dusty debris discs in an attempt to identify gaseous emission. we do not detect any gaseous components in these 20 systems, consistent with the occurrence rate that we calculated. | arxiv:2002.01936 |
we study the three - body systems of $ { } ^ { 3 } \ mathrm { he } $ and $ pd $ scattering and demonstrate, both analytically and numerically, that a new $ pd $ three - body force is needed at next - to - leading order in pionless effective field theory. we also show that at leading order these observables require no new three - body force beyond what is necessary to describe $ nd $ scattering. we include electromagnetic effects by iterating only diagrams that involve a single photon exchange in the three - body sector. | arxiv:1402.5441 |
mosquito - borne diseases ( mbds ), such as dengue virus, chikungunya virus, and west nile virus, cause over one million deaths globally every year. because many such diseases are spread by the aedes and culex mosquitoes, tracking these larvae becomes critical in mitigating the spread of mbds. even as citizen science grows and obtains larger mosquito image datasets, the manual annotation of mosquito images becomes ever more time - consuming and inefficient. previous research has used computer vision to identify mosquito species, and the convolutional neural network ( cnn ) has become the de - facto for image classification. however, these models typically require substantial computational resources. this research introduces the application of the vision transformer ( vit ) in a comparative study to improve image classification on aedes and culex larvae. two vit models, vit - base and cvt - 13, and two cnn models, resnet - 18 and convnext, were trained on mosquito larvae image data and compared to determine the most effective model to distinguish mosquito larvae as aedes or culex. testing revealed that convnext obtained the greatest values across all classification metrics, demonstrating its viability for mosquito larvae classification. based on these results, future research includes creating a model specifically designed for mosquito larvae classification by combining elements of cnn and transformer architecture. | arxiv:2209.07718 |
a string is the one - dimensional generalization of a point particle. in this sense, the analog of a cloud of dust would be a cloud of strings. in this work, we consider a cloud of strings around a regular solution in general gelativity. we consider the bardeen solution and the simpson - - visser solution, analyzing the consequences of the cloud in the regularity and in the energy conditions. actually, the presence of the cloud could make the energy density positive when compared to the simpson - - visser case. we verify that the usual bardeen solution becomes singular in the presence of the cloud of string while the simpson - - visser solution is still regular, violating the energy conditions, as the usual solution. we also calculate some thermodynamic quantities to evaluate how a cloud of strings influences the thermodynamics of the solutions. | arxiv:2210.05383 |
we review the procedure by which we implemented the non - abelian gauss ' s law and constructed gauge - invariant fields for qcd in the temporal ( weyl ) gauge. we point out that the operator - valued transformation that transforms gauge - dependent temporal - gauge fields into gauge - invariant ones has the formal structure of a gauge transformation. we express the ` ` standard ' ' hamiltonian for temporal - gauge qcd entirely in terms of gauge - invariant fields, calculate the commutation rules for these fields, and compare them to earlier work on coulomb - gauge qcd. we also discuss multiplicities of gauge - invariant temporal - gauge fields that belong to different topological sectors and that, in previous work, were shown to be based on the same underlying gauge - dependent temporal - gauge fields. we relate these multiplicities of gauge - invariant fields to gribov copies. we argue that gribov copies appear in the temporal gauge, but not when the theory is represented in terms of gauge - dependent fields and gauss ' s law is left unimplemented. there are gribov copies of the gauge - invariant gauge field, which can be constructed when gauss ' s law is implemented. | arxiv:hep-th/0201069 |
from april 2013 to the beginning of august 2013, the aspect spectrometer was installed on a cold neutron beam facility at the institut laue - langevin ( ill ) in order to realize a high - precision measurement of the electron - antineutrino angular correlation coefficient a. among all the upgrades that were made during the past years, a new state - of - the - art acquisition system has been tested during this beam time. this internship report details the behavior of this new system. | arxiv:1907.04855 |
this study investigates the modulation of particle fluxes at the earths surface influenced by the intensity and orientation of the interplanetary magnetic field ( imf ) carried by the coronal mass ejecta ( icme ). we examine how imf and its bz component, opposing the magnetosphere, significantly enhance geomagnetic activity through magnetic reconnection. this reconnection facilitates increased penetration of solar wind particles into the magnetosphere, thus amplifying the fluxes registered by terrestrial particle detectors and enhancing particle fluxes through reduced cutoff rigidity ( magnetospheric effect, me ). conversely, the orientation of the bz component is less crucial for a forbush decrease ( fd ) ; instead, the strength of the ejecta ' s scalar magnetic field ( b ) predominates, potentially triggering a significant fd. the study explores how magnetic field variations influence the flux of neutrons and muons, effectively modifying the observed rates of cosmic ray influx. comprehensive data from the wind magnetometer and aragats spectrometers underline the direct relationship between icme magnetic configurations and variations in ground - level particle fluxes. moreover, we discover that the energy spectra of additional particles during me are limited to 10 mev due to the low energy of solar protons entering the terrestrial atmosphere. in contrast, the energy spectra of the missing fd particles can extend up to 100 mev, demonstrating that magnetic traps and cradles formed by interactions between ejecta and earth ' s magnetic fields can also deflect medium - energy solar protons. these insights advance our understanding of geomagnetic modulation of particle fluxes and bolster predictive models of space weather impacts on particle detection technologies. | arxiv:2406.16159 |
. | arxiv:2402.06671 |
in this work, a new way to represent japanese animation ( anime ) is presented. we applied a minimum spanning tree to show the relation between anime. the distance between anime is calculated through three similarity measurements, namely crew, score histogram, and topic similarities. finally, the centralities are also computed to reveal the most significance anime. the result shows that the minimum spanning tree can be used to determine the similarity anime. furthermore, by using centralities calculation, we found some anime that are significant to others. | arxiv:1606.03048 |
we prove that the ns cubic superstring field theories are classically equivalent, regardless of the choice of y _ { - 2 } in their definition, and illustrate it by an explicit evaluation of the action of erler ' s solution. we then turn to examine this solution. first, we explain that its cohomology is trivial also in the ramond sector. then, we show that the boundary state corresponding to it is identically zero. we conclude that this solution is indeed a closed string vacuum solution despite the absence of a tachyon field on the bps d - brane. | arxiv:0905.3501 |
piecewise - deterministic markov processes combine continuous in time dynamics with jump events, the rates of which generally depend on the continuous variables and thus are not constants. this leads to a problem in a monte - carlo simulation of such a system, where, at each step, one must find the time instant of the next event. the latter is determined by an integral equation and usually is rather slow in numerical implementation. we suggest a reformulation of the next event problem as an ordinary differential equation where the independent variable is not the time but the cumulative rate. this reformulation is similar to the h \ ' enon approach to efficiently constructing the poincar \ ' e map in deterministic dynamics. the problem is then reduced to a standard numerical task of solving a system of ordinary differential equations with given initial conditions on a prescribed interval. we illustrate the method with a stochastic morris - lecar model of neuron spiking with stochasticity in the opening and closing of voltage - gated ion channels. | arxiv:2501.06507 |
we studied in detail the propagation of a massive tachyonic scalar field in the background of a five - dimensional ( $ 5d $ ) einstein - - yang - - mills - - born - - infeld - - dilaton black string : the massive klein - - gordon equation was solved, exactly. next we obtained complete analytical expressions for the greybody factor, absorption cross - section, and decay - rate for the tachyonic scalar field in the geometry under consideration. the behaviors of the obtained results are graphically represented for different values of the theory ' s free parameters. we also discuss why tachyons should be used instead of ordinary particles for the analytical derivation of the greybody factor of the dilatonic $ 5d $ black string. | arxiv:1806.03446 |
the beatrix ( beam expander testing x - ray facility ) project is an x - ray apparatus under construction at inaf / oab to generate a broad ( 200 x 60 mm2 ), uniform and low - divergent x - ray beam within a small lab ( 6 x 15 m2 ). beatrix will consist of an x - ray source in the focus a grazing incidence paraboloidal mirror to obtain a parallel beam, followed by a crystal monochromation system and by an asymmetrically - cut diffracting crystal to perform the beam expansion to the desired size. once completed, beatrix will be used to directly perform the quality control of focusing modules of large x - ray optics such as those for the athena x - ray observatory, based on either silicon pore optics ( baseline ) or slumped glass optics ( alternative ), and will thereby enable a direct quality control of angular resolution and effective area on a number of mirror modules in a short time, in full x - ray illumination and without being affected by the finite distance of the x - ray source. however, since the individual mirror modules for athena will have an optical quality of 3 - 4 arcsec hew or better, beatrix is required to produce a broad beam with divergence below 1 - 2 arcsec, and sufficient flux to quickly characterize the psf of the module without being significantly affected by statistical uncertainties. therefore, the optical components of beatrix have to be selected and / or manufactured with excellent optical properties in order to guarantee the final performance of the system. in this paper we report the final design of the facility and a detailed performance simulation. | arxiv:1610.09258 |
matrix rigidity is a notion put forth by valiant as a means for proving arithmetic circuit lower bounds. a matrix is rigid if it is far, in hamming distance, from any low rank matrix. despite decades of efforts, no explicit matrix rigid enough to carry out valiant ' s plan has been found. recently, alman and williams showed, contrary to common belief, that the $ 2 ^ n \ times 2 ^ n $ hadamard matrix could not be used for valiant ' s program as it is not sufficiently rigid. in this note we observe a similar ` non rigidity ' phenomena for any $ q ^ n \ times q ^ n $ matrix $ m $ of the form $ m ( x, y ) = f ( x + y ) $, where $ f : f _ q ^ n \ to f _ q $ is any function and $ f _ q $ is a fixed finite field of $ q $ elements ( $ n $ goes to infinity ). the theorem follows almost immediately from a recent lemma of croot, lev and pach which is also the main ingredient in the recent solution of the cap - set problem. | arxiv:1708.01646 |
we have carried out a study of the neutral hydrogen in the direction of the x - ray source 1e 161348 - 5055, a compact central object ( cco ) located in the interior of the supernova remnant ( snr ) rcw 103. the hi 21 cm line observations were carried out using the australia telescope compact array, complemented with single dish data from the parkes radio telescope to recover information at all spatial scales. we derive a distance to rcw 103 of 3. 3 kpc, in agreement with previous distance measurements. we have also detected a small hole in the hi emission which is positionally and kinematically coincident with the location of the cco which confirms the association between the snr and the cco. this is the third case of a depression in hi emission seemingly associated with ccos in snrs. the characteristic parameters of the holes such as their size, eccentricity and evacuated mass are similar in all three cases. we estimate the absorbing hi column density towards 1e 161348 - 5055 to be ~ 6 x 10 ^ { 21 } cm ^ { - 2 }, a value compatible with a blackbody solution for the cco x - ray emission. however, the implied brightness temperature is very high comparedto most neutron stars. moreover, the strong long - term variability in x - rays favours the hypothesis that 1e 161348 - 5055 is an accreting binary sourcerather than an isolated, cooling neutron star. an analysis of the continuum image obtained at 1. 4 ghz from these observations shows no trace of a pulsar wind nebula around 1e 161348 - 5055, in spite of it being a young object. | arxiv:astro-ph/0310100 |
data science involves working with larger datasets that often require advanced computational and statistical methods to analyze. data scientists often work with unstructured data such as text or images and use machine learning algorithms to build predictive models. data science often uses statistical analysis, data preprocessing, and supervised learning. = = cloud computing for data science = = cloud computing can offer access to large amounts of computational power and storage. in big data, where volumes of information are continually generated and processed, these platforms can be used to handle complex and resource - intensive analytical tasks. some distributed computing frameworks are designed to handle big data workloads. these frameworks can enable data scientists to process and analyze large datasets in parallel, which can reduce processing times. = = ethical consideration in data science = = data science involves collecting, processing, and analyzing data which often includes personal and sensitive information. ethical concerns include potential privacy violations, bias perpetuation, and negative societal impacts. machine learning models can amplify existing biases present in training data, leading to discriminatory or unfair outcomes. = = see also = = python ( programming language ) r ( programming language ) data engineering big data machine learning bioinformatics astroinformatics topological data analysis list of open - source data science software = = references = = | https://en.wikipedia.org/wiki/Data_science |
a graph $ g $ is cyclically $ c $ - edge - connected if there is no set of fewer than $ c $ edges that disconnects $ g $ into at least two cyclic components. we prove that if a $ ( k, g ) $ - cage $ g $ has at most $ 2m ( k, g ) - g ^ 2 $ vertices, where $ m ( k, g ) $ is the moore bound, then $ g $ is cyclically $ ( k - 2 ) g $ - edge - connected, which equals the number of edges separating a $ g $ - cycle, and every cycle - separating $ ( k - 2 ) g $ - edge - cut in $ g $ separates a cycle of length $ g $. in particular, this is true for unknown cages with $ ( k, g ) \ in \ { ( 3, 13 ), ( 3, 14 ), ( 3, 15 ), ( 4, 9 ), ( 4, 10 ) $, $ ( 4, 11 ), $ $ ( 5, 7 ), ( 5, 9 ), ( 5, 10 ), ( 5, 11 ), ( 6, 7 ), ( 9, 7 ) \ } $ and also the potential missing moore graph with degree $ 57 $ and diameter $ 2 $. keywords : cage, cyclic connectivity, girth, lower bound | arxiv:2503.07400 |
motivated by a classical correspondence between magnetic flows and sub - riemannian geometry, first established by montgomery, we undertake a systematic study of magnetic flows on sub - riemannian manifolds. we focus on three - dimensional contact manifolds, and we show that magnetic fields are naturally defined through rumin differential forms. we provide a geometric interpretation of the sub - riemannian magnetic geodesic flow, demonstrating that it can be understood as a geodesic flow on a suitably defined lifted sub - riemannian structure, which is of engel type when the magnetic field is non - vanishing. in the general case, when the magnetic field might be vanishing, we investigate the geometry of this lifted structure, characterizing properties such as its step and the abnormal trajectories in terms of the analytical features of the magnetic field. | arxiv:2504.09274 |
a hyperbolic problem wich combines a classical ( dirichlet ) and a non - local contraint is considered. the existence and uniqueness of strong solutions are proved, we use a functionnal analysis method based on a priori estimate and on the density of the range of the operator generated by the considered problem. | arxiv:0811.2499 |
in this work we propose a novel algorithm for multiple - event localization for hydraulic fracture monitoring ( hfm ) through the exploitation of the sparsity of the observed seismic signal when represented in a basis consisting of space time propagators. we provide explicit construction of these propagators using a forward model for wave propagation which depends non - linearly on the problem parameters - the unknown source location and mechanism of fracture, time and extent of event, and the locations of the receivers. under fairly general assumptions and an appropriate discretization of these parameters we first build an over - complete dictionary of generalized radon propagators and assume that the data is well represented as a linear superposition of these propagators. exploiting this structure we propose sparsity penalized algorithms and workflow for super - resolution extraction of time overlapping multiple seismic events from single well data. | arxiv:1305.2169 |
we have developed a suite of novel infrared - blocking filters made by embedding scattering particles in a polymer aerogel substrate. our developments allow us to tune the spectral performance of the filters based on both the composition of the base aerogel material and the properties of the scattering particles. our filters are targeted for use in a variety of applications, from ground - based cmb experiments to planetary science probes. we summarize the formulations we have fabricated and tested to date, including several polyimide base aerogel formulations incorporating a range of size distributions of diamond scattering particles. we also describe the spectral characterization techniques used to measure the filters ' optical properties, including the development of a mm - wave fourier transform spectrometer testbed. | arxiv:2208.04257 |
for the first time, differential cross sections for the production of w - bosons in conjunction with up to three jets, computed at next - to leading order in qcd and including parton shower corrections, are presented and compared to recent experimental data from the large hadron collider. | arxiv:1201.5882 |
in this proceedings, we report measurements of the third harmonic coefficient of the azimuthal anisotropy, $ v _ { 3 } $, known as triangular flow. the analysis is for charged particles near midrapidity in au + au collisions at $ \ sqrt { s _ { nn } } $ = 200 gev, based on data from the star experiment at the relativistic heavy ion collider. triangular flow as a function of centrality, pseudorapidity and transverse momentum are reported using various methods, including a study of the signal for particle pairs as a function of their pseudorapidity separation. results are compared with other experiments and model predictions. | arxiv:1209.0244 |
the basic tool for the study of the electroweak phase transition is $ v _ { eff } ( \ phi, t ) $, the one - loop finite - temperature effective potential, improved by all - loop resummations of the most important infrared contributions. in this paper we perform, as a first step towards a full analysis of the standard model case, a detailed study of the effective potential of the scalar theory. we show that subleading corrections to the self - energies lead to spurious terms, linear in the field - dependent mass $ m ( \ phi ) $, in the daisy - improved effective potential. consistency at subleading order requires the introduction of superdaisy diagrams, which prevent the appearance of linear terms. the resulting $ v _ { eff } ( \ phi, t ) $ for the scalar theory hints at a phase transition which is either second - order or very weakly first - order. | arxiv:hep-ph/9206227 |
hierarchy of reasons, slight command over the contextual force of critieria, stubborn unwillingness to pursue an argument where it leads, stark naivete concerning the efficacy of explanation and so on? in that case, i think, we are perfectly justified in rejecting astrology as irrational.... astrology simply fails to meet the multifarious demands of legitimate reasoning. this poor reasoning includes appeals to ancient astrologers such as kepler despite any relevance of topic or specific reasoning, and vague claims. the claim that evidence for astrology is that people born at roughly " the same place have a life pattern that is very similar " is vague, but also ignores that time is reference frame dependent and gives no definition of " same place " despite the planet ' s moving in the reference frame of the solar system. other comments by astrologers are based on severely erroneous interpretations of basic physics, such as the general belief by medieval astrologers that the geocentric solar system corresponded to an atom. further, james noted that response to criticism also relies on faulty logic, an example of which was a response to twin studies with the statement that coincidences in twins are due to astrology, but any differences are due to " heredity and environment ", while for other astrologers the issues are too difficult and they just want to get back to their astrology. : 32 further, to astrologers, if something appears in their favour, they may latch upon it as proof, while making no attempt to explore its implications, preferring to refer to the item in favour as definitive ; possibilities that do not make astrology look favourable are ignored. : 33 = = = quinean dichotomy = = = from the quinean web of knowledge, there is a dichotomy where one must either reject astrology or accept astrology but reject all established scientific disciplines that are incompatible with astrology. : 24 = = tests of astrology = = astrologers often do not make verifiable predictions, but instead make vague statements that are not falsifiable. : 48 – 49 across several centuries of testing, the predictions of astrology have never been more accurate than that expected by chance alone. one approach used in testing astrology quantitatively is through blind experiment. when specific predictions from astrologers were tested in rigorous experimental procedures in the carlson test, the predictions were falsified. all controlled experiments have failed to show any effect. : 24 = = = mars effect = = = in 1955, | https://en.wikipedia.org/wiki/Astrology_and_science |
we study the statistical distribution of the closest encounter between observations computed along different trajectories of a mixing dynamical system. at the limit of large trajectories, the distribution is of gumbel type and depends on the length of the trajectories and on the generalized dimensions of the image measure. it is also modulated by an extremal index, for which we give a formula in the case of expanding maps of the interval and regular observations. we discuss the implications of these results for the study of physical systems. | arxiv:2104.13642 |
is expected to suppress the sign problem and to make the lattice calculation possible. for the obtained gauge configurations of the coexistence system, matter - side quantities are evaluated through their measurement only for the matter part $ m $. by the calculations with gradually decreasing $ \ lambda $ and their extrapolation to $ \ lambda = 0 $, physical quantities in finite density qcd are expected to be estimated. | arxiv:1707.05996 |
in this article we investigate the effects of single derivative mixing in massive bosonic fields. in the regime of large mixing, we show that this leads to striking changes of the field dynamics, delaying the onset of classical oscillations and decreasing, or even eliminating, the friction due to hubble expansion. we highlight this phenomenon with a few examples. in the first example, we show how an axion like particle can have its number abundance parametrically enhanced. in the second example, we demonstrate that the qcd axion can have its number abundance enhanced allowing for misalignment driven axion dark matter all the way down to $ f _ a $ of order astrophysical bounds. in the third example, we show that the delayed oscillation of the scalar field can also sustain a period of inflation. in the last example, we present a situation where an oscillating scalar field is completely frictionless and does not dilute away in time. | arxiv:1912.08817 |
probing quantumness in curved spacetime is regarded as one of fundamental and important topics in the framework of relativistic quantum information. in this work, we focus on the theoretical feasibility of probing quantum properties in de sitter ( ds ) and anti - de sitter ( ads ) spacetimes via detectors. by employing the unruh - dewitt detector coupled with a massless scalar field, which is treated as an open system, quantum uncertainty and quantum coherence in both ds and ads spacetimes are investigated. our analysis reveals that the acceleration in ds spacetime and the boundary conditions in ads spacetime significantly impact the detector ' s evolution in the initial stage. notably, both of the uncertainty and coherence will oscillate with the initial state being in a superposition state, however the high temperature is able to suppress their oscillation. interestingly, it is found that the constant values of the final uncertainty and coherence are identical as those in ds and ads spacetimes, which are determined by the ratio of energy gap to temperature. hence, the current exploration offers insight into quantumness in ds and ads spacetimes, and might be helpful to facilitate the curved - spacetime - based quantum information processing. | arxiv:2502.07167 |
in this paper, we establish that, for statistically convex - cocompact actions, contracting elements are exponentially generic in counting measure. among others, the following exponential genericity results are obtained as corollaries for the set of hyperbolic elements in relatively hyperbolic groups, the set of rank - 1 elements in cat ( 0 ) groups, and the set of pseudo - anosov elements in mapping class groups. regarding a proper action, the set of non - contracting elements is proven to be growth - negligible. in particular, for mapping class groups, the set of pseudo - anosov elements is generic in a sufficiently large subgroup, provided that the subgroup has purely exponential growth. by roblin ' s work, we obtain that the set of hyperbolic elements is generic in any discrete group action on cat ( - 1 ) space with finite bms measure. applications to the number of conjugacy classes of non - contracting elements are given for non - rank - 1 geodesics in cat ( 0 ) groups with rank - 1 elements. | arxiv:1707.06006 |
we present results of a comprehensive analysis of the polarization characteristics of grb 200503a and grb 201009a observed with the cadmium zinc telluride imager ( czti ) on board astrosat. despite these grbs being reasonably bright, they were missed by several spacecraft and had thus far not been localized well, hindering polarization analysis. we present positions of these bursts obtained from the inter - planetary network ( ipn ) and the newly developed czti localization pipeline. we then undertook polarization analyses using the standard czti pipeline. we cannot constrain the polarization properties for grb 200503a, but find that grb 201009a has a high degree of polarization. | arxiv:2411.00410 |
we discuss a robust method to simultaneously fit a complex model both to the complex impedance and the noise data for transition - edge sensors ( tes ). it is based on a differential evolution ( de ) algorithm, providing accurate and repeatable results with only a small increase in computational cost compared to the standard least squares ( ls ) fitting method. test fits are made using both de and ls methods, and the results compared with previously determined best fits, with varying initial value deviations and limit ranges for the parameters. the robustness of de is demonstrated with successful fits even when parameter limits up to a factor of 5 from the known values were used. it is shown that the least squares fitting becomes unreliable beyond a 10 % deviation from the known values. | arxiv:1909.05643 |
the attenuation length and refractive index of liquid xenon for intrinsic scintillation light ( 178nm ) have been measured in a single experiment. the value obtained for attenuation length is 364 + - 18 mm. the refractive index is found to be 1. 69 + - 0. 02. both values were measured at a temperature of 170 + - 1 k. | arxiv:physics/0307044 |
motivated by the theorem of gy \ h ori and lov \ ' asz, we consider the following problem. for a connected graph $ g $ on $ n $ vertices and $ m $ edges determine the number $ p ( g, k ) $ of unordered solutions of positive integers $ \ sum _ { i = 1 } ^ k m _ i = m $ such that every $ m _ i $ is realized by a connected subgraph $ h _ i $ of $ g $ with $ m _ i $ edges such that $ \ cup _ { i = 1 } ^ ke ( h _ i ) = e ( g ) $. we also consider the vertex - partition analogue. we prove various lower bounds on $ p ( g, k ) $ as a function of the number $ n $ of vertices in $ g $, as a function of the average degree $ d $ of $ g $, and also as the size $ \ mathrm { cmc } _ r ( g ) $ of $ r $ - partite connected maximum cuts of $ g $. those three lower bounds are tight up to a multiplicative constant. we also prove that the number $ \ pi ( g, k ) $ of unordered $ k $ - tuples with $ \ sum _ { i = 1 } ^ kn _ i = n $, that are realizable by vertex partitions into $ k $ connected parts of respective sizes $ n _ 1, n _ 2, \ dots, n _ k $, is $ \ omega ( d ^ { k - 1 } ) $. | arxiv:2210.11032 |
in this paper we study the formation of nanodrops on curved surfaces ( both convex and concave ) by means of molecular dynamics simulations, where the particles interact via a lennard - jones potential. we find that the contact angle is not affected by the curvature of the substrate, in agreement with previous experimental findings. this means that the change in curvature of the drop in response to the change in curvature of the substrate can be predicted from simple geometrical considerations, under the assumption that the drop ' s shape is a spherical cap, and that the volume remains unchanged through the curvature. the resulting prediction is in perfect agreement with the simulation results, for both convex and concave substrates. in addition, we calculate the line tension, namely by fitting the contact angle for different size drops to the modified young equation. we find that the line tension for concave surfaces is larger than for convex surfaces, while for zero curvature it has a clear maximum. this feature is found to be correlated with the number of particles in the first layer of the liquid on the surface. | arxiv:1707.04111 |
quantum computing provides a powerful framework for tackling computational problems that are classically intractable. the goal of this paper is to explore the use of quantum computers for solving relevant problems in systems and control theory. in the recent literature, different quantum algorithms have been developed to tackle binary optimization, which plays an important role in various control - theoretic problems. as a prototypical example, we consider the verification of interval matrix properties such as non - singularity and stability on a quantum computer. we present a quantum algorithm solving these problems and we study its performance in simulation. our results demonstrate that quantum computers provide a promising tool for control whose applicability to further computationally complex problems remains to be explored. | arxiv:2403.17711 |
we describe taylor towers for spaces of knots arising from goodwillie - weiss calculus of the embedding functor and extend the configuration space integrals of bott and taubes from spaces of knots to the stages of the towers. we show that certain combinations of integrals, indexed by trivalent diagrams, yield cohomology classes of the stages of the tower, just as they do for ordinary knots. | arxiv:math/0401282 |
we experimentally investigate impact dynamics of a microliter water droplet on a hydrophobic microgrooved surface. the surface is fabricated using photolithography and high - speed visualization is employed to record the time - varying droplet shapes in transverse as well as longitudinal direction. the effect of the pitch of the grooved surface and weber number on droplet dynamics and impact outcome are studied. at low pitch and weber number, the maximum droplet spreading is found to be greater in the longitudinal direction than the transverse direction to the grooves. the preferential spreading inversely scales with the pitch at a given weber number. in this case, the outcome is no bouncing ( nb ) ; however, this changes at larger pitch or weber number. under these conditions, the following outcomes are obtained as function of the pitch and weber number - droplet completely bounces off the surface ( cb ), bouncing occurs with droplet breakup ( bdb ) or no bouncing due to cassie to wenzel wetting transition ( nbw ). in bdb and nbw, the liquid penetrates the grooves partially or completely beneath the droplet due to the wetting transition. the former results in droplet breakup alongside bouncing while the latter suppresses the bouncing. these outcomes are demarcated on weber number - dimensionless pitch plane and the proposed regime map suggests the existence of a critical weber number or pitch for the transition from one regime to the other. cb and bdb are quantified by plotting coefficient of restitution of the bouncing droplet and volume of daughter droplet left on the surface, respectively. the critical weber number needed for the transition from cb to bdb is estimated using an existing mathematical model and is compared with the measurements. the comparison is good and provides insights in mechanism of the liquid penetration into the grooves. | arxiv:1708.08582 |
some theoretical aspects of $ b $ physics are reviewed. these include a brief recapitulation of information on weak quark transitions as described by the cabibbo - kobayashi - maskawa ( ckm ) matrix, a description of cp asymmetries in $ b $ decays to cp eigenstates and self - tagging modes, a discussion of final - state phases in $ b $ and charm decays, some topics on $ b _ s $ properties and decays, the prospects for unusual excited $ b $ states opened by discovery of some narrow $ c \ bar s $ resonances, and the prospects for seeing the heavier $ q = 1 / 3 $ quarks predicted in some extended grand unified theories. | arxiv:hep-ph/0306284 |
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