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we propose a lattice density - functional theory for { \ it ab initio } quantum chemistry or physics as a route to an efficient approach that approximates the full configuration interaction energy and orbital occupations for molecules with strongly - correlated electrons. we build on lattice density - functional theory for the hubbard model by deriving kohn - sham equations for a reduced then full quantum chemistry hamiltonian, and demonstrate the method on the potential energy curves for the challenging problem of modelling elongating bonds in a linear chain of six hydrogen atoms. here the accuracy of the bethe - ansatz local - density approximation is tested for this quantum chemistry system and we find that, despite this approximate functional being designed for the hubbard model, the shapes of the potential curves generally agree with the full configuration interaction results. although there is a discrepancy for very stretched bonds, this is lower than when using standard density - functional theory with the local - density approximation. | arxiv:1902.08516 |
we prove that the moduli space of polarized $ k3 $ surfaces of genus eleven with $ n $ marked points is unirational when $ n \ leq 6 $ and uniruled when $ n \ leq7 $. as a consequence, we settle a long standing but not proved assertion about the unirationality of $ \ cal { m } _ { 11, n } $ for $ n \ leq6 $. we also prove that the moduli space of polarized $ k3 $ surfaces of genus eleven with $ 9 $ marked points has non - negative kodaira dimension. | arxiv:1705.05290 |
spoken language understanding ( slu ) acts as a critical component in goal - oriented dialog systems. it typically involves identifying the speakers intent and extracting semantic slots from user utterances, which are known as intent detection ( id ) and slot filling ( sf ). slu problem has been intensively investigated in recent years. however, these methods just constrain sf results grammatically, solve id and sf independently, or do not fully utilize the mutual impact of the two tasks. this paper proposes a multi - head self - attention joint model with a conditional random field ( crf ) layer and a prior mask. the experiments show the effectiveness of our model, as compared with state - of - the - art models. meanwhile, online education in china has made great progress in the last few years. but there are few intelligent educational dialog applications for students to learn foreign languages. hence, we design an intelligent dialog robot equipped with different scenario settings to help students learn communication skills. | arxiv:1905.11393 |
we apply our first - principles method to simulate the transient electrical response through carbon nanotube based conductors under time - dependent bias voltages, and report the dynamic conductance for a specific system. we find that the electrical response of the carbon nanotube device can be mapped onto an equivalent classical electric circuit. this is confirmed by studying the electric response of a simple model system and its equivalent circuit. | arxiv:0801.3914 |
a conceptual consideration is given to a zero - energy state ( zes ) at the surface of unconventional superconductors. the reflection coefficients in normal - metal / superconductor ( ns ) junctions are calculated based on a phenomenological description of the reflection processes of a quasiparticle. the phenomenological theory reveals the importance of the sign change in the pair potential for the formation of the zes. the zes is observed as the zero - bias conductance peak ( zbcp ) in the differential conductance of ns junctions. the split of the zbcp due to broken time - reversal symmetry states is naturally understood in the present theory. we also discuss effects of external magnetic fields on the zbcp. | arxiv:cond-mat/0307345 |
the aditya - l1 is the first space - based solar observatory of the indian space research organization ( isro ). the spacecraft will carry seven payloads providing uninterrupted observations of the sun from the first lagrangian point. aditya - l1 comprises four remote sensing instruments, { \ it viz. } a coronagraph observing in visible and infrared, a full disk imager in near ultra - violet ( nuv ), and two full - sun integrated spectrometers in soft x - ray and hard x - ray. in addition, there are three instruments for in - situ measurements, including a magnetometer, to study the magnetic field variations during energetic events. aditya - l1 is truly a mission for multi - messenger solar astronomy from space that will provide comprehensive observations of the sun across the electromagnetic spectrum and in - situ measurements in a broad range of energy, including magnetic field measurements at l1. | arxiv:2212.13046 |
the last few years have seen the discovery of a number of new aspects of type i x - ray bursts : the extremely energetic and long duration superbursts, intermediate duration bursts at low luminosities, mhz qpos, and burst oscillations. these discoveries promise a new understanding of nuclear burning on accreting neutron stars, and offer a chance to use observations to probe neutron star properties. i discuss what we can learn from future long term monitoring with mirax. | arxiv:astro-ph/0603352 |
in this report we obtain higher order asymptotic expansions of solutions to wave equations with frictional and viscoelastic damping terms. although the diffusion phenomena are dominant, differences between the solutions we deal with and those of heat equations can be seen by comparing the second order expansions of them. in order to analyze such effects we consider the weighted l1 initial data. we also give some lower bounds which show the optimality of obtained expansions. | arxiv:1807.10020 |
in distributed signal processing frames play significant role as redundant building blocks. bemrose et. al. were motivated from this concept, as a result they introduced weaving frames in hilbert space. weaving frames have useful applications in sensor networks, likewise weaving k - frames have been proved to be useful during signal reconstructions from the range of a bounded linear operator k. this article focuses on study, characterization of weaving k - frames in different spaces. paley - wiener type perturbation and conditions on erasure of frame components have been assembled to scrutinize woven - ness of k - frames. | arxiv:1907.08757 |
for an arbitrary integer n that is at least 2, this paper gives a construction of a strictly stationary, n - tuplewise independent sequence of ( non - degenerate ) bounded random variables such that the central limit theorem fails to hold. the sequence is in part an adaptation of a non - stationary example with similar properties constructed by one of the authors ( arp ) in a paper published in 1998. | arxiv:0810.1707 |
gravitational wave echoes, if they exist, could encode important information of new physics from the strong gravity regime. current echo searches usually assume constant interval echoes ( cies ) a priori, although unequal interval echoes ( uies ) are also possible. despite of its simplicity, the using of cie templates need to be properly justified, especially given the high sensitivity of future gravitational wave detectors. in this paper, we assess the necessity of uie templates in echo searches. by reconstructing injected uie signals with both cie and uie templates, we show that the cie template may significantly misinterpret the echo signals if the variation of the interval is greater than the statistical errors of the interval, which is further confirmed by a bayesian analysis on model stelection. we also forecast the constraints on the echo intervals given by future gw detectors such as advanced ligo and einstein telescope. | arxiv:1904.00212 |
i review the capabilities of h $ \ alpha $ observations to constrain some aspects of the current models of the interstellar medium. in particular, it is shown that turbulence is a necessary ingredient of any viable model, since most of the energy produced by supernova explosions and ionizing radiation is stored in kinetic form in the ism. various forms of turbulent energy dissipation, including cloud collisions, are analyzed. two additional aspects, concerning the existence of galactic fountains and their relation with high velocity clouds, and the extended ionized layer of spiral galaxies are discussed ; some crucial experiments are suggested. | arxiv:astro-ph/9707262 |
we study the syzygies of canonical curves of genus $ g \ geq 3 $ over an algebraically closed field $ \ mathbb { f } $ of characteristic $ p > 0 $. we provide a new proof of generic green ' s conjecture for $ p \ geq \ frac { g + 4 } { 2 } $. using the techniques from the even - genus case, we establish a significant case of the geometric syzygy conjecture for the last syzygy space of a general even - genus canonical curve ( assuming $ p > g $ ). in characteristic 0, it was shown in prior work that this case implies the full conjecture. | arxiv:2109.12187 |
the paper presents a novel concept that analyzes and visualizes worldwide fashion trends. our goal is to reveal cutting - edge fashion trends without displaying an ordinary fashion style. to achieve the fashion - based analysis, we created a new fashion culture database ( fcdb ), which consists of 76 million geo - tagged images in 16 cosmopolitan cities. by grasping a fashion trend of mixed fashion styles, the paper also proposes an unsupervised fashion trend descriptor ( ftd ) using a fashion descriptor, a codeword vetor, and temporal analysis. to unveil fashion trends in the fcdb, the temporal analysis in ftd effectively emphasizes consecutive features between two different times. in experiments, we clearly show the analysis of fashion trends and fashion - based city similarity. as the result of large - scale data collection and an unsupervised analyzer, the proposed approach achieves world - level fashion visualization in a time series. the code, model, and fcdb will be publicly available after the construction of the project page. | arxiv:1703.07920 |
we study a supersymmetric tensor model with four supercharges and $ o ( n ) ^ 3 $ global symmetry. the model is based on a chiral scalar superfield with three indices and quartic tetrahedral interaction in the superpotential, which is relevant below three dimensions. in the large - $ n $ limit the model is dominated by melonic diagrams. we solve the dyson - schwinger equations in superspace for generic $ d $ and extract the dimension of the chiral field and the dimensions of bilinear operators transforming in various representations of $ o ( n ) ^ 3 $. we find that all operator dimensions are real and above the unitarity bound for $ 1 < d < 3 $. our results also agree with perturbative results in $ 3 - \ varepsilon $ expansion. finally, we extract the large spin behaviour of bilinear operators and discuss the connection with lightcone bootstrap. | arxiv:2012.11600 |
ongoing and upcoming surveys in x - rays and sze are expected to jointly detect many clusters due to the large overlap in sky coverage. we show that, these clusters can be used as an ensemble of rulers to estimate the angular diameter distance, d _ a ( z ). this comes at no extra observational cost, as these clusters form a subset of a much larger sample, assembled to build cluster number counts dn / dz. on using this d _ a ( z ), the dark energy constraints can be improved by factors of 1. 5 - 4, over those from just dn / dn. even in the presence of a mass follow - up of 100 clusters ( done for mass calibration ), the dark energy constraints can be further tightened by factors of 2 - 3. adding d _ a ( z ) from clusters is similar to adding d _ l ( z ), from the sne observations ; for eg., dn / dn ( from act / spt ) plus d _ a ( z ) is comparable to dn / dz plus d _ l ( z ) in constraining omega _ m and sigma _ 8. | arxiv:1005.0388 |
procedural content generation ( pcg ) is of great interest to game design and development as it generates game content automatically. motivated by the recent learning - based pcg framework and other existing pcg works, we propose an alternative approach to online content generation and adaptation in super mario bros ( smb ). unlike most of existing works in smb, our approach exploits the synergy between rule - based and learning - based methods to produce constructive primitives, quality yet controllable game segments in smb. as a result, a complete quality game level can be generated online by integrating relevant constructive primitives via controllable parameters regarding geometrical features and procedure - level properties. also the adaptive content can be generated in real time by dynamically selecting proper constructive primitives via an adaptation criterion, e. g., dynamic difficulty adjustment ( dda ). our approach is of several favorable properties in terms of content quality assurance, generation efficiency and controllability. extensive simulation results demonstrate that the proposed approach can generate controllable yet quality game levels online and adaptable content for dda in real time. | arxiv:1510.07889 |
screen - reader software enables blind users to access large segments of electronic content, particularly if accessibility standards are followed. unfortunately, this is not true for much of the content written in physics, mathematics, and other stem - disciplines, due to the strong reliance on mathematical symbols and expressions, which screen - reader software generally fails to process correctly. a large portion of such content is based on source documents written in latex, which are rendered to pdf or html for online distribution. unfortunately, the resulting pdf documents are essentially inaccessible, and the html documents greatly vary in accessibility, since their rendering using standard tools is cumbersome at best. the paper explores the possibility of generating standards - compliant, accessible html from latex sources using large language models. it is found that the resulting documents are highly accessible, with possible complications occurring when the artificial intelligence tool starts to interpret the content. | arxiv:2306.02480 |
exploring combination of antiferromagnetic ( afm ) spintronics and anomalous valley hall effect ( avhe ) is one of the most important questions for valleytronic applications. the key to address this issue is to achieve spin splitting around the valleys in afm systems. here, we propose a possible way for achieving avhe in hexagonal afm monolayer, which involves the isovalent alloying. this can break the combined symmetry ( $ pt $ symmetry ) of spatial inversion ( $ p $ ) and time reversal ( $ t $ ), giving rise to spin splitting. more specifically, the large spin splitting around the fermi energy level owes to $ d $ orbital mismatch among these different transition metal ions. based on first - principles calculations, the proposed way can be verified in out - of - plane afm $ \ mathrm { crmoc _ 2s _ 6 } $ monolayer, which possesses spontaneous valley polarization and spitting splitting, providing possibility to realize avhe. it is also proved that tensile strain can strengthen the valley splitting and maintain the out - of - plane afm ordering. our works provide an experimentally feasible way for developing afm valleytronic devices. | arxiv:2405.18826 |
quantum gates in experiment are inherently prone to errors that need to be characterized before they can be corrected. full characterization via quantum process tomography is impractical and often unnecessary. for most practical purposes, it is enough to estimate more general quantities such as the average fidelity. here we use a unitary 2 - design and twirling protocol for efficiently estimating the average fidelity of clifford gates, to certify a 7 - qubit entangling gate in a nuclear magnetic resonance quantum processor. compared with more than $ 10 ^ 8 $ experiments required by full process tomography, we conducted 1656 experiments to satisfy a statistical confidence level of 99 %. the average fidelity of this clifford gate in experiment is 55. 1 %, and rises to 87. 5 % if the infidelity due to decoherence is removed. the entire protocol of certifying clifford gates is efficient and scalable, and can easily be extended to any general quantum information processor with minor modifications. | arxiv:1411.7993 |
the band topology of magnetic semimetals is of interest both from the fundamental science point of view and with respect to potential spintronics and memory applications. unfortunately, only a handful of suitable topological semimetals with magnetic order have been discovered so far. one such family that hosts these characteristics is the antiperovskites, a $ _ 3 $ bo, a family of 3d dirac semimetals. the a = eu $ ^ { 2 + } $ compounds magnetically order with multiple phases as a function of applied magnetic field. here, by combining band structure calculations with neutron diffraction and magnetic measurements, we establish the antiperovskite eu $ _ 3 $ pbo as a new topological magnetic semimetal. this topological material exhibits a multitude of different topological phases with ordered eu moments which can be easily controlled by an external magnetic field. the topological phase diagram of eu $ _ 3 $ pbo includes an antiferromagnetic dirac phase, as well as ferro - and ferrimagnetic phases with both weyl points and nodal lines. for each of these phases, we determine the bulk band dispersions, the surface states, and the topological invariants by means of $ \ textit { ab - initio } $ and tight - binding calculations. our discovery of these topological phases introduces eu $ _ 3 $ pbo as a new platform to study and manipulate the interplay of band topology, magnetism, and transport. | arxiv:2207.12434 |
for a given real number $ a $ we define the sequence $ \ { e _ { n, a } \ } $ by $ e _ { 0, a } = 1 $ and $ e _ { n, a } = - a \ sum _ { k = 1 } ^ { [ n / 2 ] } \ binom n { 2k } e _ { n - 2k, a } $ $ ( n \ ge 1 ) $, where $ [ x ] $ is the greatest integer not exceeding $ x $. since $ e _ { n, 1 } = e _ n $ is the n - th euler number, $ e _ { n, a } $ can be viewed as a natural generalization of euler numbers. in this paper we deduce some identities and an inversion formula involving $ \ { e _ { n, a } \ } $, and establish congruences for $ e _ { 2n, a } \ mod { 2 ^ { { \ rm ord } _ 2n + 8 } } $, $ e _ { 2n, a } \ pmod { 3 ^ { { \ rm ord } _ 3n + 5 } } $ and $ e _ { 2n, a } \ pmod { 5 ^ { { \ rm ord } _ 5n + 4 } } $ provided that $ a $ is a nonzero integer, where $ { \ rm ord } _ pn $ is the least nonnegative integer $ \ alpha $ such that $ p ^ { \ a } \ mid n $ but $ p ^ { \ a + 1 } \ nmid n $. | arxiv:1307.7370 |
long - form story generation task aims to produce coherent and sufficiently lengthy text, essential for applications such as novel writingand interactive storytelling. however, existing methods, including llms, rely on rigid outlines or lack macro - level planning, making it difficult to achieve both contextual consistency and coherent plot development in long - form story generation. to address this issues, we propose dynamic hierarchical outlining with memory - enhancement long - form story generation method, named dome, to generate the long - form story with coherent content and plot. specifically, the dynamic hierarchical outline ( dho ) mechanism incorporates the novel writing theory into outline planning and fuses the plan and writing stages together, improving the coherence of the plot by ensuring the plot completeness and adapting to the uncertainty during story generation. a memory - enhancement module ( mem ) based on temporal knowledge graphs is introduced to store and access the generated content, reducing contextual conflicts and improving story coherence. finally, we propose a temporal conflict analyzer leveraging temporal knowledge graphs to automatically evaluate the contextual consistency of long - form story. experiments demonstrate that dome significantly improves the fluency, coherence, and overall quality of generated long stories compared to state - of - the - art methods. | arxiv:2412.13575 |
the presented work investigates a surface dielectric barrier discharge ( sdbd ) operated dry synthetic air as the working gas using a combination of experimental measurements and simulations. the primary objective is to characterize the production and consumption dynamics of reactive oxygen and nitrogen species to enhance the understanding of their formation and facilitate control of the discharge for applications. densities of o3, no2, and n2o5 are measured under varying gas flow rates, utilizing optical absorption spectroscopy as the diagnostic method. a semi - empirical chemical kinetics model is developed based on a compilation of reactions from previous studies on similar types of discharges. the results reveal two previously known and distinct operating modes, with a mode transition occurring between the modes as the flow rate is varied. the results indicate the dependency of the mode transition on the density of sufficiently vibrationally excited nitrogen molecules, which is represented in the model by an increased vibrational temperature at lower gas flow rates. furthermore, key reactions responsible for the production and consumption of ozone and nitrogen oxides are identified, providing insight into the importance of macroscopic parameters, such as gas temperatures and different time constants, that influence the nonlinear balance of these reactions. | arxiv:2502.04851 |
of new, higher - paying jobs. studies have found that computers did not create significant net technological unemployment. due to artificial intelligence being far more capable than computers, and still being in its infancy, it is not known whether it will follow the same trend ; the question has been debated at length among economists and policymakers. a 2017 survey found no clear consensus among economists on whether ai would increase long - term unemployment. according to the world economic forum ' s " the future of jobs report 2020 ", ai is predicted to replace 85 million jobs worldwide, and create 97 million new jobs by 2025. from 1990 to 2007, a study in the u. s. by mit economist daron acemoglu showed that an addition of one robot for every 1, 000 workers decreased the employment - to - population ratio by 0. 2 %, or about 3. 3 workers, and lowered wages by 0. 42 %. concerns about technology replacing human labor however are long - lasting. as us president lyndon johnson said in 1964, " technology is creating both new opportunities and new obligations for us, opportunity for greater productivity and progress ; obligation to be sure that no workingman, no family must pay an unjust price for progress. " upon signing the national commission on technology, automation, and economic progress bill. = = = = security = = = = with the growing reliance of technology, there have been security and privacy concerns along with it. billions of people use different online payment methods, such as wechat pay, paypal, alipay, and much more to help transfer money. although security measures are placed, some criminals are able to bypass them. in march 2022, north korea used blender. io, a mixer which helped them to hide their cryptocurrency exchanges, to launder over $ 20. 5 million in cryptocurrency, from axie infinity, and steal over $ 600 million worth of cryptocurrency from the game ' s owner. because of this, the u. s. treasury department sanctioned blender. io, which marked the first time it has taken action against a mixer, to try to crack down on north korean hackers. the privacy of cryptocurrency has been debated. although many customers like the privacy of cryptocurrency, many also argue that it needs more transparency and stability. = = = environmental = = = technology can have both positive and negative effects on the environment. environmental technology, describes an array of technologies which seek to reverse, | https://en.wikipedia.org/wiki/Technology |
the energy structure and the thermodynamics of ferrimagnetic heisenberg chains of alternating spins s and s are described in terms of the schwinger bosons and modified spin waves. in the schwinger representation, we average the local constraints on the bosons and diagonalize the hamiltonian at the hartree - fock level. in the holstein - primakoff representation, we optimize the free energy in two different ways introducing an additional constraint on the staggered magnetization. a new modified spin - wave scheme, which employs a lagrange multiplier keeping the native energy structure free from temperature and thus differs from the original takahashi scheme, is particularly stressed as an excellent language to interpret one - dimensional quantum ferrimagnetism. other types of one - dimensional ferrimagnets and the antiferromagnetic limit s = s are also mentioned. | arxiv:cond-mat/0401476 |
we present a perturbative calculation of the transverse parton distribution functions in all partonic channels up to next - to - next - to - leading order based on a gauge invariant operator definition. we demonstrate for the first time that such a definition works beyond the first non - trivial order. we extract the coefficient functions relevant for a next - to - next - to - next - to - leading logarithmic $ q _ t $ resummation in a large class of processes at hadron colliders. | arxiv:1401.1222 |
we present a comprehensive dataset of optical and near - infrared photometry and spectroscopy of type ~ ia supernova ( sn ) 2016hnk, combined with integral field spectroscopy ( ifs ) of its host galaxy, mcg - 01 - 06 - 070, and nearby environment. properties of the sn local environment are characterized by means of single stellar population synthesis applied to ifs observations taken two years after the sn exploded. sn 2016hnk spectra are compared to other 1991bg - like sne ia, 2002es - like sne ia, and ca - rich transients. in addition, abundance stratification modelling is used to identify the various spectral features in the early phase spectral sequence and the dataset is also compared to a modified non - lte model previously produced for the sublumnious sn 1999by. sn 2016hnk is consistent with being a sub - luminous ( m $ _ { \ rm b } = - 16. 7 $ mag, s $ _ { \ rm bv } $ = 0. 43 $ \ pm $ 0. 03 ), highly reddened object. ifs of its host galaxy reveals both a significant amount of dust at the sn location, as well as residual star formation and a high proportion of old stellar populations in the local environment compared to other locations in the galaxy, which favours an old progenitor for sn 2016hnk. inspection of a nebular spectrum obtained one year after maximum contains two narrow emission lines attributed to the forbidden [ ca ii ] $ \ lambda \ lambda $ 7291, 7324 doublet with a doppler shift of 700 km s $ ^ { - 1 } $. based on various observational diagnostics, we argue that the progenitor of sn 2016hnk was likely a near chandrasekhar - mass ( $ m _ { \ rm ch } $ ) carbon - oxygen white dwarf that produced 0. 108 $ m _ \ odot $ of $ ^ { 56 } $ ni. our modeling suggests that the narrow [ ca ii ] features observed in the nebular spectrum are associated with $ ^ { 48 } $ ca from electron capture during the explosion, which is expected to occur only in white dwarfs that explode near or at the $ m _ { \ rm ch } $ limit. | arxiv:1904.10034 |
event argument extraction ( eae ) is pivotal for extracting structured information from unstructured text, yet it remains challenging due to the complexity of real - world document - level eae. we propose a novel definition - augmented heuristic - driven prompting ( dhp ) method to enhance the performance of large language models ( llms ) in document - level eae. our method integrates argument extraction - related definitions and heuristic rules to guide the extraction process, reducing error propagation and improving task accuracy. we also employ the chain - of - thought ( cot ) method to simulate human reasoning, breaking down complex problems into manageable sub - problems. experiments have shown that our method achieves a certain improvement in performance over existing prompting methods and few - shot supervised learning on document - level eae datasets. the dhp method enhances the generalization capability of llms and reduces reliance on large annotated datasets, offering a novel research perspective for document - level eae. | arxiv:2409.00214 |
astronomically, there are viable mechanisms for distributing organic material throughout the milky way. biologically, the destructive effects of ultraviolet light and cosmic rays means that the majority of organisms arrive broken and dead on a new world. the likelihood of conventional forms of panspermia must therefore be considered low. however, the information content of dam - aged biological molecules might serve to seed new life ( necropanspermia ). | arxiv:1011.0101 |
autonomous car racing is a challenging task, as it requires precise applications of control while the vehicle is operating at cornering speeds. traditional autonomous pipelines require accurate pre - mapping, localization, and planning which make the task computationally expensive and environment - dependent. recent works propose use of imitation and reinforcement learning to train end - to - end deep neural networks and have shown promising results for high - speed racing. however, the end - to - end models may be dangerous to be deployed on real systems, as the neural networks are treated as black - box models devoid of any provable safety guarantees. in this work we propose a decoupled approach where an optimal end - to - end controller and a state prediction end - to - end model are learned together, and the predicted state of the vehicle is used to formulate a control barrier function for safeguarding the vehicle to stay within lane boundaries. we validate our algorithm both on a high - fidelity carla driving simulator and a 1 / 10 - scale rc car on a real track. the evaluation results suggest that using an explicit safety controller helps to learn the task safely with fewer iterations and makes it possible to safely navigate the vehicle on the track along the more challenging racing line. | arxiv:2303.02267 |
while parameter - efficient fine - tuning ( peft ) techniques like low - rank adaptation ( lora ) offer computationally efficient adaptations of large language models ( llms ), their practical deployment often assumes centralized data and training environments. however, real - world scenarios frequently involve distributed, privacy - sensitive datasets that require decentralized solutions. federated learning ( fl ) addresses data privacy by coordinating model updates across clients, but it is typically based on centralized aggregation through a parameter server, which can introduce bottlenecks and communication constraints. decentralized learning, in contrast, eliminates this dependency by enabling direct collaboration between clients, improving scalability and efficiency in distributed environments. despite its advantages, decentralized llm fine - tuning remains underexplored. in this work, we propose dec - lora, a decentralized fine - tuning algorithm for llms based on lora. through extensive experiments on bert and llama - 2 models, we demonstrate that dec - lora achieves performance comparable to centralized lora under various conditions, including data heterogeneity and quantization constraints. additionally, we provide a rigorous theoretical guarantee proving the convergence of our algorithm to a stationary point for non - convex and smooth loss functions. these findings highlight the potential of dec - lora for scalable llm fine - tuning in decentralized environments. | arxiv:2501.15361 |
deep neural networks are powerful tools for biomedical image segmentation. these models are often trained with heavy supervision, relying on pairs of images and corresponding voxel - level labels. however, obtaining segmentations of anatomical regions on a large number of cases can be prohibitively expensive. thus there is a strong need for deep learning - based segmentation tools that do not require heavy supervision and can continuously adapt. in this paper, we propose a novel perspective of segmentation as a discrete representation learning problem, and present a variational autoencoder segmentation strategy that is flexible and adaptive. our method, called segmentation auto - encoder ( sae ), leverages all available unlabeled scans and merely requires a segmentation prior, which can be a single unpaired segmentation image. in experiments, we apply sae to brain mri scans. our results show that sae can produce good quality segmentations, particularly when the prior is good. we demonstrate that a markov random field prior can yield significantly better results than a spatially independent prior. our code is freely available at https : / / github. com / evanmy / sae. | arxiv:2004.13903 |
a dictionary is a set of finite words over some finite alphabet x. the omega - power of a dictionary v is the set of infinite words obtained by infinite concatenation of words in v. lecomte studied in [ omega - powers and descriptive set theory, jsl 2005 ] the complexity of the set of dictionaries whose associated omega - powers have a given complexity. in particular, he considered the sets $ w ( { \ bf \ si } ^ 0 _ { k } ) $ ( respectively, $ w ( { \ bf \ pi } ^ 0 _ { k } ) $, $ w ( { \ bf \ delta } _ 1 ^ 1 ) $ ) of dictionaries $ v \ subseteq 2 ^ \ star $ whose omega - powers are $ { \ bf \ si } ^ 0 _ { k } $ - sets ( respectively, $ { \ bf \ pi } ^ 0 _ { k } $ - sets, borel sets ). in this paper we first establish a new relation between the sets $ w ( { \ bf \ sigma } ^ 0 _ { 2 } ) $ and $ w ( { \ bf \ delta } _ 1 ^ 1 ) $, showing that the set $ w ( { \ bf \ delta } _ 1 ^ 1 ) $ is " more complex " than the set $ w ( { \ bf \ sigma } ^ 0 _ { 2 } ) $. as an application we improve the lower bound on the complexity of $ w ( { \ bf \ delta } _ 1 ^ 1 ) $ given by lecomte. then we prove that, for every integer $ k \ geq 2 $, ( respectively, $ k \ geq 3 $ ) the set of dictionaries $ w ( { \ bf \ pi } ^ 0 _ { k + 1 } ) $ ( respectively, $ w ( { \ bf \ si } ^ 0 _ { k + 1 } ) $ ) is " more complex " than the set of dictionaries $ w ( { \ bf \ pi } ^ 0 _ { k } ) $ ( respectively, $ w ( { \ bf \ si } ^ 0 _ { k } ) $ ). | arxiv:0911.3307 |
this paper proposes a spatial - radon domain ct image reconstruction model based on data - driven tight frames ( srd - ddtf ). the proposed srd - ddtf model combines the idea of joint image and radon domain inpainting model of \ cite { dong2013x } and that of the data - driven tight frames for image denoising \ cite { cai2014data }. it is different from existing models in that both ct image and its corresponding high quality projection image are reconstructed simultaneously using sparsity priors by tight frames that are adaptively learned from the data to provide optimal sparse approximations. an alternative minimization algorithm is designed to solve the proposed model which is nonsmooth and nonconvex. convergence analysis of the algorithm is provided. numerical experiments showed that the srd - ddtf model is superior to the model by \ cite { dong2013x } especially in recovering some subtle structures in the images. | arxiv:1601.00811 |
this paper presents a histogram based reversible data hiding ( rdh ) scheme, which divides image pixels into different cell frequency bands to sort them for data embedding. data hiding is more efficient in lower cell frequency bands because it provides more accurate prediction. using pixel existence probability in some pixels of ultra - low cell frequency band, another sorting is performed. employing these two novel sorting methods in combination with the hiding intensity analysis that determines optimum prediction error, we improve the quality of the marked image especially for low embedding capacities. in effect, comparing to existent rdh algorithms, the hiding capacity is increased for a specific level of the distortion for the marked image. experimental results confirm that the proposed algorithm outperforms state of the art ones. | arxiv:1907.05129 |
in the zermelo - - fraenkel set theory with the axiom of choice a forcing notion is " $ \ kappa $ - distributive " if and only if it is " $ \ kappa $ - sequential ". we show that without the axiom of choice this equivalence fails, even if we include a weak form of the axiom of choice, the principle of dependent choice for $ \ kappa $. still, the equivalence may still hold along with very strong failures of the axiom of choice, assuming the consistency of large cardinal axioms. we also prove that while a $ \ kappa $ - distributive forcing notion may violate dependent choice, it must preserve the axiom of choice for families of size $ \ kappa $. on the other hand, a $ \ kappa $ - sequential can violate the axiom of choice for countable families. we also provide a condition of " quasiproperness " which is sufficient for the preservation of dependent choice, and is also necessary if the forcing notion is sequential. | arxiv:2112.14103 |
a suggestion for an observational test of the difference between quantum mechanics and noncontextual hidden variables theories requires the measurement of a product of two commuting observables without measuring either observable separately. a proposal has been made for doing this, but it is shown to be problematic. | arxiv:quant-ph/0208127 |
advanced embedded system technology is one of the key driving forces behind the rapid growth of cyber - physical system ( cps ) applications. cyber - physical systems are comprised of multiple coordinating and cooperating components, which are often software intensive and interacting with each other to achieve unprecedented tasks. such complex cpss have multiple attack surfaces and attack vectors that we have to secure against. towards this goal, we demonstrate a multilevel runtime safety and security monitor framework where there are monitors across the cps for detection and isolation of attacks. we implement the runtime monitors on fpga using a stream - based runtime verification tool called tessla. we demonstrate our monitoring scheme for an autonomous emergency braking ( aeb ) cps system. | arxiv:2009.09533 |
helical structure of dna by james watson and francis crick in 1953, marked the transition to the era of molecular genetics. from the 1950s onwards, biology has been vastly extended in the molecular domain. the genetic code was cracked by har gobind khorana, robert w. holley and marshall warren nirenberg after dna was understood to contain codons. the human genome project was launched in 1990 to map the human genome. = = chemical basis = = = = = atoms and molecules = = = all organisms are made up of chemical elements ; oxygen, carbon, hydrogen, and nitrogen account for most ( 96 % ) of the mass of all organisms, with calcium, phosphorus, sulfur, sodium, chlorine, and magnesium constituting essentially all the remainder. different elements can combine to form compounds such as water, which is fundamental to life. biochemistry is the study of chemical processes within and relating to living organisms. molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including molecular synthesis, modification, mechanisms, and interactions. = = = water = = = life arose from the earth ' s first ocean, which formed some 3. 8 billion years ago. since then, water continues to be the most abundant molecule in every organism. water is important to life because it is an effective solvent, capable of dissolving solutes such as sodium and chloride ions or other small molecules to form an aqueous solution. once dissolved in water, these solutes are more likely to come in contact with one another and therefore take part in chemical reactions that sustain life. in terms of its molecular structure, water is a small polar molecule with a bent shape formed by the polar covalent bonds of two hydrogen ( h ) atoms to one oxygen ( o ) atom ( h2o ). because the o – h bonds are polar, the oxygen atom has a slight negative charge and the two hydrogen atoms have a slight positive charge. this polar property of water allows it to attract other water molecules via hydrogen bonds, which makes water cohesive. surface tension results from the cohesive force due to the attraction between molecules at the surface of the liquid. water is also adhesive as it is able to adhere to the surface of any polar or charged non - water molecules. water is denser as a liquid than it is as a solid ( or ice ). this unique property of water allows ice to float above liquid water such as ponds, lakes, and oceans, thereby ins | https://en.wikipedia.org/wiki/Biology |
this paper introduces bifr \ " ost, a novel 3d - aware framework that is built upon diffusion models to perform instruction - based image composition. previous methods concentrate on image compositing at the 2d level, which fall short in handling complex spatial relationships ( $ \ textit { e. g. } $, occlusion ). bifr \ " ost addresses these issues by training mllm as a 2. 5d location predictor and integrating depth maps as an extra condition during the generation process to bridge the gap between 2d and 3d, which enhances spatial comprehension and supports sophisticated spatial interactions. our method begins by fine - tuning mllm with a custom counterfactual dataset to predict 2. 5d object locations in complex backgrounds from language instructions. then, the image - compositing model is uniquely designed to process multiple types of input features, enabling it to perform high - fidelity image compositions that consider occlusion, depth blur, and image harmonization. extensive qualitative and quantitative evaluations demonstrate that bifr \ " ost significantly outperforms existing methods, providing a robust solution for generating realistically composited images in scenarios demanding intricate spatial understanding. this work not only pushes the boundaries of generative image compositing but also reduces reliance on expensive annotated datasets by effectively utilizing existing resources in innovative ways. | arxiv:2410.19079 |
focus. this is done to have better equality in the expenditure of the country. = = = brazil = = = in 2011, nossas, a brazilian organization that helps citizens and groups express their struggles and make change was founded. they have also made their own tech platform, bonde. it is a platform in which other organizations can use to make their own website and use tools to spread their reach. apart from bonde, nossas also provides support and programs to those who want to become activists. = = = chile = = = citizenlab is a civic technology company that is in many countries and local governments. citizen lab works so citizens are better informed in democracy to make public decisions. in 2019, they expanded to chile and made teams to support them with engagement, budgeting, planning, and more. = = = colombia = = = founded in 2016, movilizatorio was made to encourage and promote citizen participation in democracy. movilizatorio works on many projects to address various issues in the country including political, social, behavioral, and cultural issues. one of their projects was able to get the local community together because an elementary school had not started classes. shortly after the movement started, after getting signatures and going to the secretary of education, classes started. = = = panama = = = fundacion para el desarrollo de la libertad ciudadana ( english : foundation for the development of citizen freedom ) is an organization founded in 1995. the main goal is to improve democracy in panama. ways of achieving this is promoting transparency with the government to prevent corruption and engaging with citizens to increase democratic citizen participation. = = = paraguay = = = tedic is an organization founded in 2012 that defends digital rights of citizens. tedic researches information on cybersecurity, copyright, artificial intelligence, and more. they also promote and develop their own software for people to use to make social change. they have worked on topics such as personal data, freedom of expression, gender and digital inclusion, and more. = = = uruguay = = = a tu servicio, a civic tech platform, informs users and citizens on the country ' s public health services so that they are able to make informed decisions on medical providers. the platform was founded in 2015. it features a list users can use to compare 2 different health care providers. the data includes wait times, prices, number of users, workers, and more. data uruguay is an organization that works on issues surrounding data. they work with other organizations and community | https://en.wikipedia.org/wiki/Civic_technology |
in this work, we study the spin transport at the ferromagnet $ | $ noncentrosymmetric superconductor ( f $ | $ ncsc ) junction of a ferromagnet $ | $ noncentrosymmetric superconductor $ | $ ferromagnet ( f $ | $ ncsc $ | $ f ) spin valve. we investigate the tunnelling spin - conductance ( tsc ), spin current and spin tunnelling magneto - resistance ( stmr ), and their dependence on various important parameters like rashba spin - orbit coupling ( rsoc ), strength and orientation of magnetization, an external in - plane magnetic field, barrier strength and a significant fermi wavevector mismatch ( fwm ) at the ferromagnetic and superconducting regions. the study has been carried out for different singlet - triplet mixing of the ncsc gap parameter. we develop bogoliubov - de gennes ( bdg ) hamiltonian and use the extended blonder - tinkham - klapwijk ( btk ) approach along with the scattering matrix formalism to calculate the scattering coefficients. our results strongly suggest that the tsc is highly dependent on rsoc, magnetization strength and its orientation, and singlet - triplet mixing of the gap parameter. it is observed that ncsc with moderate rsoc shows maximum conductance for a partially opaque barrier in presence of low external magnetic field. for a strongly opaque barrier and a nearly transparent barrier a moderate value and a low value of field respectively are found to be suitable. moreover, ncsc with large singlet component is appeared to be useful. in addition, for ncsc with large rsoc and low magnetization strength, a giant stmr ( $ \ % $ ) is observed. we have also seen that the spin current is strongly magnetization orientation dependent. with the increase in bias voltage spin current increases in transverse direction, but the component along the direction of flow is almost independent. | arxiv:1906.05081 |
electromagnetic reactions on light nuclei are fundamental to advance our understanding of nuclear structure and dynamics. the perturbative nature of the electromagnetic probes allows to clearly connect measured cross sections with the calculated structure properties of nuclear targets. we present an overview on recent theoretical ab - initio calculations of electron - scattering and photonuclear reactions involving light nuclei. we encompass both the conventional approach and the novel theoretical framework provided by chiral effective field theories. because both strong and electromagnetic interactions are involved in the processes under study, comparison with available experimental data provides stringent constraints on both many - body nuclear hamiltonians and electromagnetic currents. we discuss what we have learned from studies on electromagnetic observables of light nuclei, starting from the deuteron and reaching up to nuclear systems with mass number a = 16. | arxiv:1407.3490 |
i generalize state - of - the - art approaches that decompose differences in the distribution of a variable of interest between two groups into a portion explained by covariates and a residual portion. the method that i propose relaxes the overlapping supports assumption, allowing the groups being compared to not necessarily share exactly the same covariate support. i illustrate my method revisiting the black - white wealth gap in the u. s. as a function of labor income and other variables. traditionally used decomposition methods would trim ( or assign zero weight to ) observations that lie outside the common covariate support region. on the other hand, by allowing all observations to contribute to the existing wealth gap, i find that otherwise trimmed observations contribute from 3 % to 19 % to the overall wealth gap, at different portions of the wealth distribution. | arxiv:2405.05759 |
the results of a modified gross - pitaevskii equation for a system of bose hard spheres trapped in a spherical harmonic potential are analyzed to study the validity regime of the standard gp equation. | arxiv:cond-mat/0011160 |
the exploitation of already deployed wireless local area networks ( wlan ) s ( e. g., wifi access points ( ap ) s ) has attracted considerable attention, as an efficient and practical method to improve the performance of beyond 4g wireless networks. in this paper, we propose a novel communication paradigm to satisfy the performance demands of future wireless networks : a hybrid cellular / wlan network architecture with wireless offloading. in contrast to the commonly adopted practice of wifi offloading, where the wlan aps have a wired backhaul ( e. g., digital subscriber line ), we propose a wireless offloading approach, where the wlan aps will share their wireless cellular broadband connection with other users. these users will select their serving node, i. e., the macro - cell enodeb or a wlan ap, based on a certain selection criterion. thus a challenging research field is originated, where interfering effects and wireless resources limitations play a dominant role. important performance metrics of the proposed hybrid scheme, including the bit error probability, the ergodic capacity and the average signal - to - interference - plus noise ratio, are theoretically studied and closed form expressions are derived for the single - user case with multiple interferers, for both identical and non - identical fading conditions. also, based on the general multi - cellular hybrid wlan - cellular concept, we first propose a intercell interference minimization approach. then we present a novel scheme for achieving frequency reuse equal to one within a single macro - cell, under specific performance criteria and constraints, that guarantee the overall cell or the individual user qos requirements. | arxiv:1311.2970 |
we show that recently constructed invariants of 3 - dimensional manifolds and of hyperkaehler manifolds ( l. rozansky and e. witten, hep - th / 9612216 ) come from characteristic classes of foliations and from gelfand - fuks cohomology. in particular, any symplectic foliation gives invariants of 3 - manifolds. our preprint has many intersections with the preprint alg - geom / 9704009 by m. kapranov. | arxiv:dg-ga/9704009 |
the yang - mills and yang - mills - higgs equations in temporal gauge are locally well - posed for small and rough initial data, which can be shown using the null structure of the critical bilinear terms. this carries over a similar result by tao for the yang - mills equations in the ( 3 + 1 ) - dimensional case to the more general yang - mills - higgs system and to general dimensions. | arxiv:1506.02533 |
in our theoretical study where we combine a nonequilibrium green ' s function ( negf ) approach with density functional theory ( dft ) we investigate compounds containing a ferrocene moiety which is connected to i ) thiol anchor groups on both sides in a para - connection, ii ) a pyridyl anchor group on one side in a meta - connection and a thiol group on the other side in a para - connection, in both cases with acetylenic spacers in between the ferrocene and the anchors. we predict possible single molecule junction geometries within a scanning tunneling microscopy ( stm ) setup where we find that the conductance trend for the set of conformations are intriguing in the sense that the conductance does not decrease while the junction length increases which we analyze and explain in terms of fermi level alignment. we also find a pattern for the current - voltage ( iv ) curves within the linear - response regime for both molecules we study, where the conductance variation with the molecular configurations is surprisingly small. | arxiv:1809.08174 |
the bernoulli sieve is the infinite " balls - in - boxes " occupancy scheme with random frequencies $ p _ k = w _ 1... w _ { k - 1 } ( 1 - w _ k ) $, where $ ( w _ k ) _ { k \ in \ mn } $ are independent copies of a random variable $ w $ taking values in $ ( 0, 1 ) $. assuming that the number of balls equals $ n $, let $ l _ n $ denote the number of empty boxes within the occupancy range. the paper proves that, under a regular variation assumption, $ l _ n $, properly normalized without centering, weakly converges to a functional of an inverse stable subordinator. proofs rely upon the observation that $ ( \ log p _ k ) $ is a perturbed random walk. in particular, some results for general perturbed random walks are derived. the other result of the paper states that whenever $ l _ n $ weakly converges ( without normalization ) the limiting law is mixed poisson. | arxiv:1104.2299 |
quantum circuit synthesis is the process in which an arbitrary unitary operation is decomposed into a sequence of gates from a universal set, typically one which a quantum computer can implement both efficiently and fault - tolerantly. as physical implementations of quantum computers improve, the need is growing for tools which can effectively synthesize components of the circuits and algorithms they will run. existing algorithms for exact, multi - qubit circuit synthesis scale exponentially in the number of qubits and circuit depth, leaving synthesis intractable for circuits on more than a handful of qubits. even modest improvements in circuit synthesis procedures may lead to significant advances, pushing forward the boundaries of not only the size of solvable circuit synthesis problems, but also in what can be realized physically as a result of having more efficient circuits. we present a method for quantum circuit synthesis using deterministic walks. also termed pseudorandom walks, these are walks in which once a starting point is chosen, its path is completely determined. we apply our method to construct a parallel framework for circuit synthesis, and implement one such version performing optimal $ t $ - count synthesis over the clifford + $ t $ gate set. we use our software to present examples where parallelization offers a significant speedup on the runtime, as well as directly confirm that the 4 - qubit 1 - bit full adder has optimal $ t $ - count 7 and $ t $ - depth 3. | arxiv:1606.07413 |
the extended black hole thermodynamics in which the cosmological constant plays the role of pressure significantly enriches the phase structure of the theory. in order to understand the extended black hole thermodynamics more precisely, we let the value of the cosmological constant vary dynamically via tunneling from one vacuum to another in a black hole induced vacuum decay. in this process, entropy of the matter / energy released by a black hole is crucial to validate the second law of thermodynamics. in other words, without taking this bulk entropy into account, entropy associated with the black hole and cosmological horizons may not always increase. since the bulk entropy is not represented by the black hole and the cosmological horizons, this result calls for a more careful interpretation of the holographic principle in which environmental effects are taken into account. | arxiv:2111.03359 |
we investigate the density distributions of finite nuclei employing a well - designed deep neural network method. we calculate the target nucleon density distributions with skyrme density functional theories, which are used to train the networks. we find that the training with only about $ 10 \ % $ nuclei ( $ 300 - 400 $ ) is sufficient to describe the nucleon density distributions of all the nuclear chart within 2 \ % relative error. the relative error comes to 5 \ % when about 200 proton ( neutron ) density distributions are used for training. we obtained very similar results for different skyrme density functional theories. therefore the ability to train networks is weakly dependent on the theoretical model. moreover, in the process of machine learning, there is a turning point showing the transition from the fermi - like distribution to the realistic skyrme distribution, which provides significant properties of convergence process. | arxiv:2012.07334 |
in recent years, the prospect of detecting gravitational waves sourced from a strongly first - order cosmological phase transition has emerged as one of the most exciting frontiers of gravitational wave astronomy. cosmological phase transitions are an essential ingredient in the standard model of particle cosmology, and help explain the mechanism for creation of matter in the early universe, provide insights into fundamental theories of physics, and shed light on the nature of dark matter. this underscores the significance of developing robust end - to - end tools for determining the resulting gravitational waves from these phase transitions. in this article we present phasetracer2, an improved version of the c + + software package phasetracer, designed for mapping cosmological phases and transitions in standard model extensions of multiple scalar fields. building on the robust framework of its predecessor, phasetracer2 extends its capabilities by including new features crucial for a more comprehensive analysis of cosmological phase transitions. it can calculate more complex properties, such as the bounce action through the path deformation method or an interface with bubbleprofiler, thermodynamic parameters, and gravitational wave spectra. its applicability has also been broadened via incorporating the dimensionally reduced effective potential for models obtained from dralgo, as well as calculations in the msbar and os - like renormalisation schemes. this modular, flexible, and practical upgrade retains the speed and stability of the original phasetracer, while significantly expanding its utility. | arxiv:2412.04881 |
we explore the joint effect of the intrinsic noise and time delay on the spatial pattern formation within a multi - scale mobile lattice model of the epithelium. the protein fluctuations are driven by transcription / translation processes in epithelial cells exchanging chemical and mechanical signals and are described by a single - gene auto - repressor model with constant delay. both deterministic and stochastic descriptions are given. we found that time delay, noise and spatial signaling can result in the protein pattern formation even when deterministic description exhibits no patterns. | arxiv:1506.03687 |
germanium nanowires with p - and n - dopants were synthesized by chemical vapor deposition and used to construct complementary field effect transistors. electrical transport and x - ray photoelectron spectroscopy data are correlated to glean the effects of ge surface chemistry to the electrical characteristics of genws. large hysteresis due to water molecules strongly bound to geo2 on genws is revealed. different oxidation behavior and hysteresis characteristics and opposite band bending due to fermi level pinning by interface states between ge and surface oxides are observed for p - and n - type genws. vacuum annealing above 400c is used to remove surface oxides and eliminate hysteresis in genw fets. high - k dielectric hfo2 films grown on clean genw surfaces by atomic layer deposition ( ald ) using an alkylamide precursor is effective serving as the first layer of surface passivation. lastly, the depletion length along the radial direction of nanowires is evaluated. the result suggests that surface effects could be dominant over the bulk properties of small diameter wires. | arxiv:cond-mat/0407186 |
in the rapidly advancing landscape of contemporary technology, power electronics assume a pivotal role across diverse applications, ranging from renewable energy systems to electric vehicles and consumer electronics. the efficacy and precision of these power electronics systems stand as cornerstones of their functionality. within this context, the integration of machine learning techniques assumes paramount significance. this article endeavors to present an extensive and comprehensive review of the machine learning techniques that find application in power electronics control and optimization. through meticulous exploration, we aim to elucidate the profound potential of these methods in shaping the future of power electronics control and optimization. | arxiv:2310.04699 |
we discuss various aspects of isometric group actions on proper metric spaces. as one application, we show that a proper and weyl transitive action on a euclidean building is strongly transitive on the maximal atlas ( the complete apartment system ) of the building. | arxiv:2109.12837 |
we demonstrate the transformation of gaussian input beams into super - gaussian beams with a quasi flat - top transverse profile by means of the conical refraction phenomenon by adjusting the ratio between the ring radius and the waist radius of the input beam to 0. 445. we discuss the beam propagation of the super - gaussian beam and show that it has a confocal parameter three times larger than the one that would be obtained from a gaussian beam. the experiments performed with a kgd ( wo4 ) 2 biaxial crystal are in good agreement with the theoretical predictions. | arxiv:1410.3790 |
we study equilibrium configurations for the euler - plateau energy with elastic modulus, which couples an energy functional of euler - plateau type with a total curvature term often present in models for the free energy of biomembranes. it is shown that the potential minimizers of this energy are highly dependent on the choice of physical rigidity parameters, and that the area of critical surfaces can be computed entirely from their boundary data. when the elastic modulus does not vanish, it is shown that axially symmetric critical immersions and critical immersions of disk type are necessarily planar domains bounded by area - constrained elasticae. the cases of topological genus zero with multiple boundary components and unrestricted genus with control on the geodesic torsion are also discussed, and sufficient conditions are given which establish the same conclusion in these cases. | arxiv:2010.00149 |
the next generation of spectroscopic surveys will target emission - line galaxies ( elgs ) to produce constraints on cosmological parameters. we study the large scale structure traced by elgs using a combination of a semi - analytical model of galaxy formation, a code that computes the nebular emission from hii regions using the properties of the interstellar medium, and a large - volume, high - resolution n - body simulation. we consider fixed number density samples where galaxies are selected by either their h $ \ alpha $, [ oiii ] $ \ lambda 5007 $ or [ oii ] $ \ lambda \ lambda 3727 - 3729 $ emission line luminosities. we investigate the assembly bias signatures of these samples, and compare them to those of stellar mass and sfr selected samples. interestingly, we find that the [ oiii ] - and [ oii ] - selected samples display scale - dependent bias on large scales and that their assembly bias signatures are also scale - dependent. both these effects are more pronounced for lower number density samples. the [ oiii ] and [ oii ] emitters that contribute most to the scale dependence tend to have a low gas - phase metallicity and are preferentially found in low - density regions. we also measure the baryon acoustic oscillation ( bao ) feature and the $ \ beta $ parameter related to the growth rate of overdensities. we find a slight tendency for the bao peak to shift toward smaller scales for [ oii ] emitters and that $ \ beta $ is scale - dependent at large scales. our results suggest that elg samples include environmental effects that should be modelled in order to remove potential systematic errors that could affect the estimation of cosmological parameters. | arxiv:2010.08500 |
we prove two theorems about tree - decompositions in the setting of coarse graph theory. first, we show that a graph $ g $ admits a tree - decomposition in which each bag is contained in the union of a bounded number of balls of bounded radius, if and only if $ g $ admits a quasi - isometry to a graph with bounded tree - width. ( the ` ` if ' ' half is easy, but the ` ` only if ' ' half is challenging. ) this generalizes a recent result of berger and seymour, concerning tree - decompositions when each bag has bounded radius. second, we show that if $ g $ admits a quasi - isometry $ \ phi $ to a graph $ h $ of bounded path - width, then $ g $ admits a quasi - isometry ( with error only an additive constant ) to a graph of bounded path - width. indeed, we will show a much stronger statement : that we can assign a non - negative integer length to each edge of $ h $, such that the same function $ \ phi $ is a quasi - isometry ( with error only an additive constant ) to this weighted version of $ h $. | arxiv:2501.09839 |
it is demonstrated that the two - point correlation function of the magnetic helicity in the case of zero mean magnetic field has anomalous scalings for both, compressible and incompressible turbulent helical fluid flow. the magnetic helicity in the limit of very high electrical conductivity is conserved. this implies that the two - point correlation function of the conserved property does not necessarily have normal scaling. the reason for the anomalous scalings of the magnetic helicity correlation function is that the magnetic field in the equation for the two - point correlation function of the magnetic helicity plays a role of a pumping with anomalous scalings. it is shown also that when magnetic fluctuations with zero mean magnetic field are generated the magnetic helicity is very small even if the hydrodynamic helicity is large. astrophysical applications of the obtained results are discussed. | arxiv:astro-ph/0205270 |
the optical lightcurve of grb010222 exhibited one of the slowest decays of any gamma - ray burst to date. its broadband properties have been difficult to explain with conventional afterglow models, as they either require the power law index of the underlying electron energy distribution to be low, $ p < 2 $, or that the outflow is quasi - spherical thus reviving the energy problem. we argue that the slow decay of grb 010222 and a linear polarization of $ 1. 36 \ pm 0. 64 $ %, is naturally explained by a jet model with continuous energy injection. the electron energy distribution then has $ p = 2. 49 \ pm0. 05 $, fully consistent with the expectation from detailed modelling of acceleration in relativistic shocks, that $ p > 2 $, thus alleviating the ` ` $ p $ - problem ' '. | arxiv:astro-ph/0209585 |
one of the key signatures of the quark - gluon plasma ( qgp ) is the modification of hadron transverse momentum differential cross - sections in heavy - ion collisions ( hic ) as compared to proton - proton ( pp ) collisions. suppression of hadron production at high transverse momenta ( $ p _ { \ rm t } $ ) in hic has been explained by the energy loss of the partons produced in the hard scattering processes which traverse the deconfined quantum chromodynamic ( qcd ) matter. the dependence of the observed suppression on the $ p _ { \ rm t } $ of the measured hadron towards higher $ p _ { \ rm t } $ is an important input for the theoretical understanding of jet quenching effects in the qgp and the nature of the energy loss, while suppression towards lower $ p _ { \ rm t } $ gives information about collective behaviour. the alice experiment at the large hadron collider ( lhc ) performs a variety of measurements including the spectra of neutral mesons and kaons at mid - rapidity in a wide $ p _ { \ rm t } $ range in pp, p - pb and pb - pb collisions. an overview of alice results in hic and pp collisions at $ \ sqrt { s _ { nn } } = $ 2. 76 tev of neutral pions, kaons and eta mesons as a function of transverse momentum ( $ p _ { \ rm t } $ ) and centrality will be presented. ratios $ \ eta $ / $ \ pi ^ { 0 } $, $ k ^ { \ pm } $ / $ \ pi ^ { \ pm } $ as well as comparisons to model calculations will also be discussed. | arxiv:1609.06106 |
we present preliminary results using nrqcd to describe heavy quarks on the milc 2 + 1 flavour dynamical extra coarse ensemble. we calculate the spectra of low lying states in bottomonium to complement earlier results on the finer milc ensembles. we then exploit the coarseness of the lattices to calculate charm propagators using nrqcd. these are used to examine the charmonium spectrum and to calclate the mass of the $ b _ c $ using nrqcd. finally we look breifly at the $ b _ d $ and $ b _ s $ systems using the imporoved staggered formalism to describe the light valence quarks. | arxiv:hep-lat/0510001 |
the development of microfluidic devices is still hindered by the lack of robust fundamental building blocks that constitute any fluidic system. an attractive approach is optical actuation because light field interaction is contactless and dynamically reconfigurable, and solutions have been anticipated through the use of optical forces to manipulate microparticles in flows. following the concept of an ' optical chip ' advanced from the optical actuation of suspensions, we propose in this survey new routes to extend this concept to microfluidic two - phase flows. first, we investigate the destabilization of fluid interfaces by the optical radiation pressure and the formation of liquid jets. we analyze the droplet shedding from the jet tip and the continuous transport in laser - sustained liquid channels. in the second part, we investigate a dissipative light - flow interaction mechanism consisting in heating locally two immiscible fluids to produce thermocapillary stresses along their interface. this opto - capillary coupling is implemented in adequate microchannel geometries to manipulate two - phase flows and propose a contactless optical toolbox including valves, droplet sorters and switches, droplet dividers or droplet mergers. finally, we discuss radiation pressure and opto - capillary effects in the context of the ' optical chip ' where flows, channels and operating functions would all be performed optically on the same device. | arxiv:0903.1739 |
we study the electric potential and field produced by disordered distributions of charge to see why clumps of charge do not produce large potentials or fields. the question is answered by evaluating the probability distribution of the electric potential and field in a totally disordered system that is overall electroneutral. an infinite system of point charges is called totally disordered if the locations of the points and the values of the charges are random. it is called electroneutral if the mean charge is zero. in one dimension, we show that the electric field is always small, of the order of the field of a single charge, and the spatial variations in potential are what can be produced by a single charge. in two and three dimensions, the electric field in similarly disordered electroneutral systems is usually small, with small variations. interestingly, in two and three dimensional systems, the electric potential is usually very large, even though the electric field is not : large amounts of energy are needed to put together a typical disordered configuration of charges in two and three dimensions, but not in one dimension. if the system is locally electroneutral - - as well as globally electroneutral - - the potential is usually small in all dimensions. the properties considered here arise from the superposition of electric fields of quasi - static distributions of charge, as in nonmetallic solids or ionic solutions. these properties are found in distributions of charge far from equilibrium. | arxiv:cond-mat/0501048 |
we measure the branching fraction of the radiative b - decay b ( b - - > phi k - gamma ) = ( 3. 46 + / - 0. 57 ^ { + 0. 39 } _ { - 0. 37 } ) 10 ^ - 6, and set an upper limit on the radiative b0 decay b ( b0 - > phi k0 gamma ) < 2. 71 10 ^ - 6 at 90 % confidence level. we also measure the direct cp asymmetry of the b - - > phi k - gamma mode a _ cp = ( - 26. 4 + / - 14. 3 + / - 4. 8 ) %. the uncertainties are statistical and systematic, respectively. these measurements are based on 207 1 / fb of data collected at the y4s resonance with the babar detector. | arxiv:hep-ex/0607037 |
the effects, upon the klein - - gordon field, of nonconformal stochastic metric fluctuations, are analyzed. it will be shown that these fluctuations allow us to consider an effective mass, i. e., the mass detected in a laboratory is not the parameter appearing in the klein - - gordon equation, but a function of this parameter and of the fluctuations of the metric. in other words, in analogy to the case of a nonrelativistic electron in interaction with a quantized electromagnetic field, we may speak of a bare mass, where the observed mass shows a dependence upon the stochastic terms included in the metric. afterwards, we prove, resorting to the influence functional, that the energy - - momentum tensor of the klein - - gordon field inherites this stochastic behavior, and that this feature provokes decoherence upon a particle immersed in the region where this tensor is present. | arxiv:gr-qc/0209004 |
we have directly observed reversal of the polarity of charged surfaces in water upon the addition of tri - and quadrivalent ions using atomic force microscopy. the bulk concentration of multivalent ions at which charge inversion reversibly occurs depends only very weakly on the chemical composition, surface structure, size and lipophilicity of the ions, but is dominated by their valence. these results support the theoretical proposal that spatial correlations between ions are the driving mechanism behind charge inversion. | arxiv:cond-mat/0406636 |
we consider a stochastic directed graph on the integers whereby a directed edge between $ i $ and a larger integer $ j $ exists with probability $ p _ { j - i } $ depending solely on the distance between the two integers. under broad conditions, we identify a regenerative structure that enables us to prove limit theorems for the maximal path length in a long chunk of the graph. the model is an extension of a special case of graphs studied by foss and konstantopoulos, markov process and related fields, 9, 413 - 468. we then consider a similar type of graph but on the ` slab ' $ \ z \ times i $, where $ i $ is a finite partially ordered set. we extend the techniques introduced in the in the first part of the paper to obtain a central limit theorem for the longest path. when $ i $ is linearly ordered, the limiting distribution can be seen to be that of the largest eigenvalue of a $ | i | \ times | i | $ random matrix in the gaussian unitary ensemble ( gue ). | arxiv:1005.4806 |
generative models have the potential to accelerate key steps in the discovery of novel molecular therapeutics and materials. diffusion models have recently emerged as a powerful approach, excelling at unconditional sample generation and, with data - driven guidance, conditional generation within their training domain. reliably sampling from high - value regions beyond the training data, however, remains an open challenge - - with current methods predominantly focusing on modifying the diffusion process itself. in this paper, we develop context - guided diffusion ( cgd ), a simple plug - and - play method that leverages unlabeled data and smoothness constraints to improve the out - of - distribution generalization of guided diffusion models. we demonstrate that this approach leads to substantial performance gains across various settings, including continuous, discrete, and graph - structured diffusion processes with applications across drug discovery, materials science, and protein design. | arxiv:2407.11942 |
nonequilibrium steady states are explicitly constructed for a noninteracting electron model of an aharonov - bohm ( ab ) ring with a quantum dot ( qd ) with the aid of asymptotic fields. the fano line shapes and ab oscillations are shown to strongly depend on the bias voltage. current fluctuations are studied as well. | arxiv:cond-mat/0410276 |
high spin polarization materials or spin filters are key components in spintronics, a niche subfield of electronics where carrier spins play a functional role. carrier transmission through these materials is " spin selective " i. e. these materials are able to discriminate between " up " and " down " spins. common spin filters include transition metal ferromagnets and their alloys, with typical spin selectivity ( or, polarization ) ~ 50 % or less. here we consider carrier transport in an archetypical one - dimensional molecular hybrid in which a single wall carbon nanotube ( swcnt ) is wrapped around by single stranded deoxyribonucleic acid ( ssdna ). by magnetoresistance measurements we show that this system can act as a spin filter with maximum spin polarization approaching ~ 74 % at low temperatures, significantly larger than transition metals under comparable conditions. inversion asymmetric helicoidal potential of the charged ssdna backbone induces a rashba spin - orbit interaction in the swcnt channel and polarizes carrier spins. our results are consistent with recent theoretical work that predicted spin dependent conductance in ssdna - swcnt hybrid. ability to generate highly spin polarized carriers using molecular functionalization can lead to magnet - less and contact - less spintronic devices in the future. this can eliminate the conductivity mismatch problem and open new directions for research in organic spintronics. | arxiv:1606.07983 |
we consider scalar two - dimensional quantum field theories with the factorizing s - matrix which has poles in the physical strip. in our previous work, we introduced the bound state operators and constructed candidate operators for observables in wedges. under some additional assumptions on the s - matrix, we show that, in order to obtain their strong commutativity, it is enough to prove the essential self - adjointness of the sum of the left and right bound state operators. this essential self - adjointness is shown up to the two - particle component. | arxiv:1602.04696 |
the optical selection rules for inter - band transitions in wse2, ws2 and mose2 transition metal dichalcogenide monolayers are investigated by polarization - resolved photoluminescence experiments with a signal collection from the sample edge. these measurements reveal a strong polarization - dependence of the emission lines. we see clear signatures of the emitted light with the electric field oriented perpendicular to the monolayer plane, corresponding to an inter - band optical transition forbidden at normal incidence used in standard optical spectroscopy measurements. the experimental results are in agreement with the optical selection rules deduced from group theory analysis, highlighting the key role played by the different symmetries of the conduction and valence bands split by the spin - orbit interaction. these studies yield a direct determination on the bright - dark exciton splitting, for which we measure 40 $ \ pm 1 $ mev and 55 $ \ pm 2 $ mev for wse2 and ws2 monolayer, respectively. | arxiv:1704.05341 |
binary populations in young star clusters show multiplicity fractions both lower and up to twice as high as those observed in the galactic field. we follow the evolution of a population of binary stars in dense and loose star clusters starting with an invariant initial binary population and a formal multiplicity fraction of unity, and demonstrate that these models can explain the observed binary properties in taurus, rho - ophiuchus, chamaeleon, orion, ic 348, upper scorpius a, praesepe, and the pleiades. the model needs to consider solely different birth densities for these regions. the evolved theoretical orbital - parameter distributions are highly probable parent distributions for the observed ones. we constrain the birth conditions ( stellar mass, m _ ecl, and half - mass radius, r _ h ) for the derived progenitors of the star clusters and the overall present - day binary fractions allowed by the present model. the results compare very well with properties of molecular cloud clumps on the verge of star formation. combining these with previously and independently obtained constraints on the birth densities of globular clusters, we identify a weak stellar mass - - half - mass radius correlation for cluster - forming cloud clumps, r _ h / pc ~ ( m _ ecl / m _ sun ) ^ ( 0. 13 + - 0. 04 ). the ability of the model to reproduce the binary properties in all the investigated young objects, covering present - day densities from 1 - 10 stars pc ^ - 3 ( taurus ) to 2x10 ^ 4 stars pc ^ - 3 ( orion ), suggests that environment - dependent dynamical evolution plays an important role in shaping the present - day properties of binary populations in star clusters, and that the initial binary properties may not vary dramatically between different environments. | arxiv:1205.1508 |
applying squashing transformation to kerr - godel black hole solutions, we present a new type of a rotating kaluza - klein black hole solution to the five - dimensional einstein - maxwell theory with a chern - simon term. the new solutions generated via the squashing transformation have no closed timelike curve everywhere outside the black hole horizons. at the infinity, the metric asymptotically approaches a twisted s ^ 1 bundle over a four - dimensional minkowski space - time. one of the remarkable features is that the solution has two independent rotation parameters along an extra dimension associated with the black hole ' s rotation and the godel ' s rotation. the space - time also admits the existence of two disconnected ergoregions, an inner ergoregion and an outer ergoregion. these two ergoregions can rotate in the opposite direction as well as in the same direction. | arxiv:0803.3873 |
permissionless blockchains offer an information environment where users can interact privately without fear of censorship. financial services can be programmatically coded via smart contracts to automate transactions without the need for human intervention or knowing user identity. this new paradigm is known as decentralized finance ( defi ). we investigate compound ( a leading defi lending protocol ) to show how it works in this novel information environment, who its users are, and what factors determine their participation. on - chain transaction data shows that loan durations are short ( 31 days on average ), and many users borrow to support leveraged investment strategies ( yield farming ). we show that systemic risk in defi arises from concentration and interconnection, and how traditional risk management practices can be challenging for defi. | arxiv:2212.05734 |
we show that there are $ k $ simple graphs whose kronecker covers are isomorphic to the bipartite kneser graph $ h ( n, k ) $, and that their chromatic numbers coincide with $ \ chi ( k ( n, k ) ) = n - 2k + 2 $. we also determine the automorphism groups of these graphs. | arxiv:2008.09051 |
modern technologies are producing datasets with complex intrinsic structures, and they can be naturally represented as matrices instead of vectors. to preserve the latent data structures during processing, modern regression approaches incorporate the low - rank property to the model and achieve satisfactory performance for certain applications. these approaches all assume that both predictors and labels for each pair of data within the training set are accurate. however, in real - world applications, it is common to see the training data contaminated by noises, which can affect the robustness of these matrix regression methods. in this paper, we address this issue by introducing a novel robust matrix regression method. we also derive efficient proximal algorithms for model training. to evaluate the performance of our methods, we apply it to real world applications with comparative studies. our method achieves the state - of - the - art performance, which shows the effectiveness and the practical value of our method. | arxiv:1611.04686 |
we present a study on the magnetic behavior of dextran - coated magnetite nanoparticles ( dm nps ) with sizes between 3 and 19 nm, synthesized by hydrothermal - assisted co - precipitation method. the decrease of saturation magnetization ( $ m _ s $ ) with decreasing particle size has been modeled by assuming the existence of a spin - disordered layer at the particle surface, which is magnetically dead. based on this core - shell model and taking into account the weight contribution of the non - magnetic coating layer ( dextran ) to the whole magnetization, the dead layer thickness ( $ t $ ) and saturation magnetization $ m _ s $ of the magnetic cores in our samples were estimated to be $ t = 6. 8 ~ \ mathrm { \ aa } $ and $ m _ s = 98. 8 ~ \ mathrm { emu / g } $, respectively. the data of $ m _ s $ were analyzed using a law of approach to saturation, indicating an increase in effective magnetic anisotropy ( $ k _ { eff } $ ) with decreasing particle size as expected from the increased surface / volume ratio in small mnps. the obtained $ k _ { eff } $ values were successfully modeled by including an extra contribution of dipolar interactions due to the formation of chain - like clusters of mnps. the surface magnetic anisotropy ( $ k _ s $ ) was estimated to be about $ k _ s = 1. 04 \ times10 ^ 5 ~ \ mathrm { j / m ^ 3 } $. our method provides a simple and accurate way to obtain the $ m _ s $ core values in surface - disordered mnps, a relevant parameter required for magnetic modeling in many applications. | arxiv:2303.14654 |
particle acceleration in plasma creates a possibility of exceptionally high accelerating gradients and appears as a very attractive option for future linear electron - positron and / or photon - photon colliders. these high accelerating gradients were already demonstrated in a number of experiments. however, a linear collider requires exceptionally high beam brightness which still needs to be demonstrated. in this article we discuss major phenomena which limit the beam brightness of accelerated beam and, consequently, the collider luminosity. | arxiv:1608.02498 |
the stability of two entangled spins dressed by electrons is studied by calculating the scattering phase shifts. the interaction between electrons is interpreted by fully relativistic qed and the screening effect is described phenomenologically in the debye exponential form $ e ^ { - \ alpha r } $. our results show that if the ( einstein - podolsky - rosen - ) epr - type states are kept stable under the interaction of qed, the spatial wave function must be parity - dependent. the spin - singlet state $ s = 0 $ and the polarized state $ \ frac 1 { \ sqrt { 2 } } ( \ mid + - > - \ mid - + > ) $ along the z - axis \ qtr { bf } { \ } give rise to two different kinds of phase shifts \ qtr { bf } {. } interestingly, the interaction between electrons in the spin - singlet pair is found to be attractive. such an attraction could be very useful when we extract the entangled spins from superconductors. a mechanism to filter the entangled spins is also discussed. | arxiv:quant-ph/0510016 |
detection of blazar pc scale counter - jets is difficult, but it can provide invaluable insight into the relativistic effects, radiative processes and the complex mechanisms of jet production, collimation and accelation in blazars. we build on recent populations models ( optimized using the mojave apparent velocity and redshift distributions ) in order to derive the distribution of jet - to - counter - jet ratios and the flux densities of the counter - jet at different frequencies, in an effort to set minimum sensitivity limits required for existing and future telescope arrays in order to detect these elusive counter - jets. we find that : for the bl lacs $ 5 \ % $ of their counter - jets have a flux - density higher than 100mjy, $ 15 \ % $ are higher than 10 mjy, and $ 32 \ % $ have higher flux - density than 1 mjy, whereas for the fsrqs $ 8 \ % $ have a flux - density higher than 10mjy, $ 17 \ % $ are higher than 1 mjy, and $ 32 \ % $ are higher than 0. 1 mjy ( at 15 ghz ). future telescopes like the ska and newly operating like e - merlin and jvla may detect up to $ 99 \ % $ of the bl lac and $ 77 \ % $ of the fsrq counter - jets. sources with both low apparent velocity and a low doppler factor make prime candidates for counter - jet detection. combining our findings with literature values we have identified five such counter - jet detection candidates. finally, we discuss possible effects beyond relativistic deboosting that may complicate the detection of counter - jets and that need to be accounted for in the interpretation of detections. | arxiv:1610.06561 |
smearing techniques are widely used in first - principles calculations of metallic and magnetic materials, where they improve the accuracy of brillouin zone sampling and lessen the impact of level - crossing instabilities. smearing introduces a fictitious electronic temperature that smooths the discontinuities of the integrands ; consequently, a corresponding fictitious entropic term arises, and needs to be considered in the total free energy functional. advanced smearing techniques - - such as methfessel - paxton and cold smearing - - have been introduced to guarantee that the system ' s total free energy remains independent of the smearing temperature at least up to the second order. in doing so, they give rise to non - monotonic occupation functions ( and, for methfessel - paxton, non - positive definite ), which can result in the chemical potential not being uniquely defined. we explore this shortcoming in detail and introduce a numerical protocol utilizing newton ' s minimization method that is able to identify the desired fermi energy. we validate the method by calculating the fermi energy of $ \ sim $ 20, 000 materials and comparing it with the results of standard bisection approaches. in passing, we also highlight how traditional approaches, based on fermi - dirac or gaussian smearing, are actually equivalent for all practical purposes, provided the smearing width is appropriately renormalized by a factor $ \ sim $ 2. 565. | arxiv:2212.07988 |
in this paper, we derive a new representation for the anger - - weber function, employing the reformulation of the method of steepest descents by c. j. howls ( howls, proc. r. soc. lond. a 439 ( 1992 ) 373 - - 396 ). as a consequence of this representation, we deduce a number of properties of the large order asymptotic expansion of the anger - - weber function, including explicit and realistic error bounds, asymptotic approximations for the late coefficients, exponentially improved asymptotic expansions, and the smooth transition of the stokes discontinuities. | arxiv:1312.2765 |
in this paper, we present zeroprompt ( figure 1 - ( a ) ) and the corresponding prompt - and - refine strategy ( figure 3 ), two simple but effective \ textbf { training - free } methods to decrease the token display time ( tdt ) of streaming asr models \ textbf { without any accuracy loss }. the core idea of zeroprompt is to append zeroed content to each chunk during inference, which acts like a prompt to encourage the model to predict future tokens even before they were spoken. we argue that streaming acoustic encoders naturally have the modeling ability of masked language models and our experiments demonstrate that zeroprompt is engineering cheap and can be applied to streaming acoustic encoders on any dataset without any accuracy loss. specifically, compared with our baseline models, we achieve 350 $ \ sim $ 700ms reduction on first token display time ( tdt - f ) and 100 $ \ sim $ 400ms reduction on last token display time ( tdt - l ), with theoretically and experimentally equal wer on both aishell - 1 and librispeech datasets. | arxiv:2305.10649 |
we derive the isometry irrep content of squashed seven - sphere compactifications of eleven - dimensional supergravity, i. e., the left - squashed ( $ ls ^ 7 $ ) with $ { \ mathcal n } = 1 $ and right - squashed ( $ rs ^ 7 $ ) with $ { \ mathcal n } = 0 $ supersymmetry, in a manner completely independent of the round sphere. then we compare this result with the spectrum obtained by higgsing the round sphere spectrum. this way we discover features of the spectra which makes it possible to argue that the only way the round spectrum can be related by a higgs mechanism to the one of $ ls ^ 7 $ is if the singletons are included in the round sphere spectrum. for this to work also in the $ rs ^ 7 $ case it seems that the gravitino of the $ ls ^ 7 $ spectrum must be replaced by a fermionic singleton present in the $ rs ^ 7 $ spectrum. | arxiv:1811.06228 |
in the space - of - histories approach to gauge fields and their quantization, the maxwell, yang - - mills and gravitational field are well known to share the property of being type - i theories, i. e. lie brackets of the vector fields which leave the action functional invariant are linear combinations of such vector fields, with coefficients of linear combination given by structure constants. the corresponding gauge - field operator in the functional integral for the in - out amplitude is an invertible second - order differential operator. for such an operator, we consider advanced and retarded green functions giving rise to a peierls bracket among group - invariant functionals. our peierls bracket is a poisson bracket on the space of all group - invariant functionals in two cases only : either the gauge - fixing is arbitrary but the gauge fields lie on the dynamical sub - space ; or the gauge - fixing is a linear functional of gauge fields, which are generic points of the space of histories. in both cases, the resulting peierls bracket is proved to be gauge - invariant by exploiting the manifestly covariant formalism. moreover, on quantization, a gauge - invariant moyal bracket is defined that reduces to i hbar times the peierls bracket to lowest order in hbar. | arxiv:hep-th/0607114 |
nothing chats was developed by company called sunbird and would have limited compatibility with apple ' s imessage. prior to its launch, android authority and ars technica expressed skepticism regarding the company ' s claims to use end - to - end encryption, reliability of message delivery and general application security, citing prior experiences with sunbird. ars technica explicitly advised readers against giving their apple username and password to a company which might not " understand and / or respect the security version of pandora ' s box they are opening ". on 17 november, shortly after launch, a third - party developer discovered that the app was using a version of a rival open - source project called bluebubbles but sunbird failed to procure a tls certificate so the application was sending users ' service credentials via insecure http. the vulnerability could allow a third - party to intercept users ' credentials ( one at a time ) and use them to impersonate the users to read and send messages. on 18 november, a different user reported that the app was sending all media attachments, including user images to error - logging service sentry, and all data to firebase, with the data being stored unencrypted in both places. at the time, the firebase database contained over 630, 000 media files. 9to5google confirmed that anyone can intercept the application ' s firebase credentials ( from their own device or any other device ), log into firebase and see all other users ' past and real - time messages. another party developed a script for downloading this data automatically and published the code to github. within 24 hours, nothing pulled the nothing chats application from google play. = = = drinks = = = beer ( 5. 1 % ) is a beer created by nothing technology. the beer was initially announced on 1 april 2023, and was made available in the uk in october 2023. the drink is brewed by free time beer co., which is based in wales. = = references = = = = external links = = official website | https://en.wikipedia.org/wiki/Nothing_(company) |
single photon detectors ( spds ) are essential technology in quantum science, quantum network, biology, and advanced imaging. to detect the small quantum of energy carried in a photon, conventional spds rely on energy excitation across either a semiconductor bandgap or superconducting gap. while the energy gap suppresses the false - positive error, it also sets an energy scale that can limit the detection efficiency of lower energy photons and spectral bandwidth of the spd. here, we demonstrate an orthogonal approach to detect single near - infrared photons using graphene calorimeters. by exploiting the extremely low heat capacity of the pseudo - relativistic electrons in graphene near its charge neutrality point, we observe an electron temperature rise up to ~ 2 k using a hybrid josephson junction. in this proof - of - principle experiment, we achieve an intrinsic quantum efficiency of 87 % ( 75 % ) with dark count < 1 per second ( per hour ) at operation temperatures as high as 1. 2 k. our results highlight the potential of electron calorimetric spds for detecting lower - energy photons from the mid - ir to microwave regimes, opening pathways to study space science in far - infrared regime, to search for dark matter axions, and to advance quantum technologies across a broader electromagnetic spectrum. | arxiv:2410.22433 |
background : genotype - phenotype maps provide a meaningful filtration of sequence space and rna secondary structures are particular such phenotypes. compatible sequences i. e. ~ sequences that satisfy the base pairing constraints of a given rna structure play an important role in the context of neutral networks and inverse folding. sequences satisfying the constraints of two structures simultaneously are called bicompatible and phenotypic change, induced by erroneously replicating populations of rna sequences, is closely connected to bicompatibility. furthermore, bicompatible sequences are relevant for riboswitch sequences, beacons of evolution, realizing two distinct phenotypes. results : we present a full loop energy model boltzmann sampler of bicompatible sequences for pairs of structures. the novel dynamic programming algorithm is based on a topological framework encapsulating the relations between loops. we utilize our sequence sampler to study the energy spectra and density of bicompatible sequences, the rankings of the structures and key properties for evolutionary transitions. conclusion : our analysis of riboswitch sequences shows that key properties of bicompatible sequences depend on the particular pair of structures. while there always exist bicompatible sequences for random structure pairs, they are less suited to facilitate transitions. we show that native riboswitch sequences exhibit a distinct signature with regards to the ranking of their two phenotypes relative to the minimum free energy, suggesting a new criterion for identifying native sequences and sequences subjected to evolutionary pressure. | arxiv:1910.00190 |
for the stochastic differential equation ( sde ) which has piecewise continuous arguments ( pcas ), is driven by multiplicative noises and its drift coefficients are dissipative, we show that the solution at integer time is a markov chain and admits a unique invariant measure. in order to inherit numerically the invariant measure of sde with pcas, we apply the backward euler ( be ) method to the equation, and prove that the numerical solution at integer time is not only markovian but also reproduces a unique numerical invariant measure. we present the time - independent weak error analysis for the method under certain hypothesis. further, we show that the numerical invariant measure converges to the original one with order 1. numerical experiments verify the theoretical analysis. | arxiv:1906.04096 |
with the increasing presence of robots in our every - day environments, improving their social skills is of utmost importance. nonetheless, social robotics still faces many challenges. one bottleneck is that robotic behaviors need to be often adapted as social norms depend strongly on the environment. for example, a robot should navigate more carefully around patients in a hospital compared to workers in an office. in this work, we investigate meta - reinforcement learning ( meta - rl ) as a potential solution. here, robot behaviors are learned via reinforcement learning where a reward function needs to be chosen so that the robot learns an appropriate behavior for a given environment. we propose to use a variational meta - rl procedure that quickly adapts the robots ' behavior to new reward functions. as a result, given a new environment different reward functions can be quickly evaluated and an appropriate one selected. the procedure learns a vectorized representation for reward functions and a meta - policy that can be conditioned on such a representation. given observations from a new reward function, the procedure identifies its representation and conditions the meta - policy to it. while investigating the procedures ' capabilities, we realized that it suffers from posterior collapse where only a subset of the dimensions in the representation encode useful information resulting in a reduced performance. our second contribution, a radial basis function ( rbf ) layer, partially mitigates this negative effect. the rbf layer lifts the representation to a higher dimensional space, which is more easily exploitable for the meta - policy. we demonstrate the interest of the rbf layer and the usage of meta - rl for social robotics on four robotic simulation tasks. | arxiv:2206.03211 |
stochastic linear combinations of some random vectors are studied where the distribution of the random vectors and the joint distribution of their coefficients are dirichlet. a method is provided for calculating the distribution of these combinations which has been studied before by some authors. our main result is a generalization of some existing results with a simpler proof. | arxiv:1603.00596 |
in epidemic or pandemic situations, resources for testing the infection status of individuals may be scarce. although group testing can help to significantly increase testing capabilities, the ( repeated ) testing of entire populations can exceed the resources of any country. we thus propose an extension of the theory of group testing that takes into account the fact that definitely specifying the infection status of each individual is impossible. our theory builds on assigning to each individual an infection status ( healthy / infected ), as well as an associated cost function for erroneous assignments. this cost function is versatile, e. g., it could take into account that false negative assignments are worse than false positive assignments and that false assignments in critical areas, such as health care workers, are more severe than in the general population. based on this model, we study the optimal use of a limited number of tests to minimize the expected cost. more specifically, we utilize information - theoretic methods to give a lower bound on the expected cost and describe simple strategies that can significantly reduce the expected cost over currently known strategies. a detailed example is provided to illustrate our theory. | arxiv:2109.05378 |
in a network of interacting quantum systems achieving fast coherent energy transfer is a challenging task. while quantum systems are susceptible to a wide range of environmental factors, in many physical settings their interactions with quantized vibrations, or phonons, of a supporting structure are the most prevalent. this leads to noise and decoherence in the network, ultimately impacting the energy - transfer process. in this work, we introduce a novel type of coherent energy - transfer mechanism for quantum systems, where phonon interactions are able to actually enhance the energy transfer. here, a shared phonon interacts with the systems and dynamically adjusts their resonances, providing remarkable directionality combined with quantum speed - up. we call this mechanism phonon - induced dynamic resonance energy transfer and show that it enables long - range coherent energy transport even in highly disordered systems. | arxiv:1304.3967 |
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