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galactic bars can affect the evolution of galaxies by redistributing gas in galaxies, possibly contributing to the cessation of star formation. recent works point to ' bar quenching ' playing an important role in massive disk galaxies like the milky way. we construct the largest ever sample of gas rich and strongly barred disc galaxies with resolved hi observations making use of both the giant meter radio telescope ( gmrt ) and the karl jansky very large array ( vla ) to collect data. this sample, called hirb ( hi rich barred ) galaxies, were identified with galaxy zoo - to find galaxies hosting a strong bar, and the arecibo legacy fast arecibo l - band feed array ( alfalfa ) blind hi survey - to identify a high hi content. we measure gas fractions, hi morphology and kinematics in each galaxy, and use archival optical data from the sloan digital sky survey ( sdss ) to reveal star - formation histories and bar properties. hirb galaxies presented here support a picture where bar quenching is playing, or will play an important role in their evolution. they also support models which show how the presence of cold gas delays and slows the development of strong bars. the galaxies with the lowest gas fractions ( still high for their mass ) show clear hi holes, dynamical advanced bars and low star formation rates, those with the highest gas fractions show little impact from their bar on the hi morphology, and are actively star - forming. how such unusual galaxies came to be is an open question. several of the hirbs have local gas rich companions. tidal interactions with these lower mass galaxies could result in an early triggering of the bar and / or accretion of hi between them. the role of environment in the evolution of the hirb galaxies will be explored in a future paper.
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arxiv:1901.01164
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the recently proposed optimization algorithm for deep neural networks sharpness aware minimization ( sam ) suggests perturbing parameters before gradient calculation by a gradient ascent step to guide the optimization into parameter space regions of flat loss. while significant generalization improvements and thus reduction of overfitting could be demonstrated, the computational costs are doubled due to the additionally needed gradient calculation, making sam unfeasible in case of limited computationally capacities. motivated by nesterov accelerated gradient ( nag ) we propose momentum - sam ( msam ), which perturbs parameters in the direction of the accumulated momentum vector to achieve low sharpness without significant computational overhead or memory demands over sgd or adam. we evaluate msam in detail and reveal insights on separable mechanisms of nag, sam and msam regarding training optimization and generalization. code is available at https : / / github. com / marlonbecker / msam.
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arxiv:2401.12033
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we study two generalizations of the pfaffian to non - antisymmetric matrices and derive their properties and relation to each other. the first approach is based on the wigner normal - form, applicable to conjugate - normal matrices, and retains most properties of the pfaffian, including that it is the square - root of the determinant. the second approach is to take the pfaffian of the antisymmetrized matrix, applicable to all matrices. we show that this formulation is equivalent to substituting a non - antisymmetric matrix into the polynomial definition of the pfaffian. we find that the two definitions differ in a positive real factor, making the second definition violate the determinant identity.
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arxiv:2209.02578
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modern power steering systems employ an electric motor drive system to provide torque assistance to the driver. the closed - loop mechanical system dynamics that impact stability, performance and steering feel are significantly impacted by the electrical dynamics of the actuator depending on the structure and tuning of the motor torque controller. this paper presents an integrated approach to the analysis of this electromechanical dynamic control interaction through mathematical modeling which is confirmed with simulations.
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arxiv:2309.13623
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the dzyaloshinkii - moriya ( dm ) interaction that originates from relativistic spin - orbit coupling in noncentrosymmetric magnets is a source of topological spin textures. we theoretically investigate the possibility of a skyrmion crystal by focusing on the role of the out - of - plane dm interaction that is different from the polar - and chiral - type dm interaction. by performing the simulated annealing for a spin model on a triangular lattice belonging to the $ d _ { 3h } $ point group, we construct low - temperature magnetic phase diagrams in an applied magnetic field. as a result, we find the instability toward different skyrmion crystals under in - plane and out - of - plane magnetic fields, where the key ingredients to stabilize the skx are different according to the magnetic field direction ; the skx is stabilized under the out - of - plane dm interaction for the in - plane magnetic field, while it is stabilized by additionally introducing an easy - axis anisotropy for the out - of - plane magnetic field. we also discuss the possible multiple - $ q $ states other than the skyrmion crystals in the presence of the out - of - plane dm interaction. our result indicates that noncentrosymmetric magnetic materials with the out - of - plane dm interaction are potential candidates to host the skyrmion crystals.
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arxiv:2206.09060
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we propose federated accelerated stochastic gradient descent ( fedac ), a principled acceleration of federated averaging ( fedavg, also known as local sgd ) for distributed optimization. fedac is the first provable acceleration of fedavg that improves convergence speed and communication efficiency on various types of convex functions. for example, for strongly convex and smooth functions, when using $ m $ workers, the previous state - of - the - art fedavg analysis can achieve a linear speedup in $ m $ if given $ m $ rounds of synchronization, whereas fedac only requires $ m ^ { \ frac { 1 } { 3 } } $ rounds. moreover, we prove stronger guarantees for fedac when the objectives are third - order smooth. our technique is based on a potential - based perturbed iterate analysis, a novel stability analysis of generalized accelerated sgd, and a strategic tradeoff between acceleration and stability.
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arxiv:2006.08950
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disease, opinions, ideas, gossip, etc. all spread on social networks. how these networks are connected ( the network structure ) influences the dynamics of the spreading processes. by investigating these relationships one gains understanding both of the spreading itself and the structure and function of the contact network. in this chapter, we will summarize the recent literature using simulation of spreading processes on top of empirical contact data. we will mostly focus on disease simulations on temporal proximity networks - - networks recording who is close to whom, at what time - - but also cover other types of networks and spreading processes. we analyze 29 empirical networks to illustrate the methods.
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arxiv:1706.09095
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language modeling has witnessed remarkable advancements in recent years, with large language models ( llms ) like chatgpt setting unparalleled benchmarks in human - like text generation. however, a prevailing limitation is the underrepresentation of languages like tamil in these cutting - edge models, leading to suboptimal performance in diverse linguistic contexts. this paper addresses this lacuna, enhancing the open - source llama model with an addition of 16, 000 tamil tokens, aiming to achieve superior text generation and comprehension in the tamil language. we strategically employ the lora methodology for efficient model training on a comprehensive tamil corpus, ensuring computational feasibility and model robustness. moreover, we introduce a tamil - translated version of the alpaca dataset and a subset of the openorca dataset tailored for instruction fine - tuning. our results showcase significant performance improvements in tamil text generation, with potential implications for the broader landscape of llms in indian languages. we further underscore our commitment to open research by making our models, datasets, and code publicly accessible, fostering further innovations in language modeling.
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arxiv:2311.05845
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we measure space - and time - correlated charge jumps on a four - qubit device, operating 107 meters below the earth ' s surface in a low - radiation, cryogenic facility designed for the characterization of low - threshold particle detectors. the rock overburden of this facility reduces the cosmic ray muon flux by over 99 % compared to laboratories at sea level. combined with 4 $ \ pi $ coverage of a movable lead shield, this facility enables quantifiable control over the flux of ionizing radiation on the qubit device. long - time - series charge tomography measurements on these weakly charge - sensitive qubits capture discontinuous jumps in the induced charge on the qubit islands, corresponding to the interaction of ionizing radiation with the qubit substrate. the rate of these charge jumps scales with the flux of ionizing radiation on the qubit package, as characterized by a series of independent measurements on another energy - resolving detector operating simultaneously in the same cryostat with the qubits. using lead shielding, we achieve a minimum charge jump rate of 0. 19 $ ^ { + 0. 04 } _ { - 0. 03 } $ mhz, almost an order of magnitude lower than that measured in surface tests, but a factor of roughly eight higher than expected based on reduction of ambient gammas alone. we operate four qubits for over 22 consecutive hours with zero correlated charge jumps at length scales above three millimeters.
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arxiv:2405.04642
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in this paper we focus our efforts on studying how a preorder and topology can be made compatible. thus we provide a characterization of those that are continuous - compatible. such a characterization states that such topologies must be finer than the so - called upper topology induced by the preorder and, thus, it clarifies which topology is the smallest one among those that make the preorder continuous. moreover, we provide sufficient conditions that allows us to discard in an easy way the continuity of a preference. in the light of the obtained results, we provide possibility counterparts of the a few celebrate impossibility theorems for continuous social social intergenerational preferences due to p. diamond, l. g. svensson and t. sakai. furthermore, we suggest quasi - pseudo - metrics as appropriate quantitative tool for reconciling topology and social intergenerational preferences. thus, we develop a metric type method which is able to guarantee possibility counterparts of the aforesaid impossibility theorems and, in addition, it is able to give numerical quantifications of the improvement of welfare. we also show that our method makes always the intergenerational preferences semi - continuous multi - utility representables in the sense of \ " { o } zg \ " { u } evern and efe o. ok. finally, in order to keep close to the classical way of measuring in the literature, a refinement of the previous method is presented in such a way that metrics are involved.
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arxiv:2402.01699
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the performance of large language models ( llms ) depends on how they are prompted, with choices spanning both the high - level prompting pattern ( e. g., zero - shot, cot, react, rewoo ) and the specific prompt content ( instructions and few - shot demonstrations ). manually tuning this combination is tedious, error - prone, and non - transferable across llms or tasks. therefore, this paper proposes autopdl, an automated approach to discover good llm agent configurations. our method frames this as a structured automl problem over a combinatorial space of agentic and non - agentic prompting patterns and demonstrations, using successive halving to efficiently navigate this space. we introduce a library implementing common prompting patterns using the pdl prompt programming language. autopdl solutions are human - readable, editable, and executable pdl programs that use this library. this approach also enables source - to - source optimization, allowing human - in - the - loop refinement and reuse. evaluations across three tasks and six llms ( ranging from 8b to 70b parameters ) show consistent accuracy gains ( $ 9. 5 \ pm17. 5 $ percentage points ), up to 68. 9pp, and reveal that selected prompting strategies vary across models and tasks.
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arxiv:2504.04365
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the concept of ratchets, driven asymmetric periodic structures giving rise to directed particle flow, has recently been generalized to a quantum ratchet mechanism for spin currents mediated through spin - orbit interaction. here we consider such systems in the coherent mesoscopic regime and generalize the proposal of a minimal spin ratchet model based on a non - interacting clean quantum wire with two transverse channels by including disorder and by self - consistently treating the charge redistribution in the nonlinear ( adiabatic ) ac - driving regime. our keldysh - green function based quantum transport simulations show that the spin ratchet mechanism is robust and prevails for disordered, though non - diffusive, mesoscopic structures. extending the two - channel to the multi - channel case does not increase the net ratchet spin current efficiency but, remarkably, yields a dc spin transmission increasing linearly with channel number.
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arxiv:1004.5279
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the unitarization of the longitudinal vector boson scattering ( vbs ) cross section by the higgs boson is a fundamental prediction of the standard model which has not been experimentally verified. one of the most promising ways to measure vbs uses events containing two leptonically - decaying same - electric - charge $ w $ bosons produced in association with two jets. however, the angular distributions of the leptons in the $ w $ boson rest frame, which are commonly used to fit polarization fractions, are not readily available in this process due to the presence of two neutrinos in the final state. in this paper we present a method to alleviate this problem by using a deep machine learning technique to recover these angular distributions from measurable event kinematics and demonstrate how the longitudinal - longitudinal scattering fraction could be studied. we show that this method doubles the expected sensitivity when compared to previous proposals.
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arxiv:1510.01691
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distant galaxies encapsulate the various stages of galaxy evolution and formation from over 95 % of the development of the universe. as early as twenty - five years ago, little was known about them, however since the first systematic survey was completed in the 1990s, increasing amounts of resources have been devoted to their discovery and research. this book summarises for the first time the numerous techniques used for observing, analysing, and understanding the evolution and formation of these distant galaxies. in this rapidly expanding research field, this text is an every - day companion handbook for graduate students and active researchers. it provides guidelines in sample selection, imaging, integrated spectroscopy and 3d spectroscopy, which help to avoid the numerous pitfalls of observational and analysis techniques in use in extragalactic astronomy. it also paves the way for establishing relations between fundamental properties of distant galaxies. at each step, the reader is assisted with numerous practical examples and ready - to - use methodology to help understand and analyse research.
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arxiv:1701.03794
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object search is a challenging task because when given complex language descriptions ( e. g., " find the white cup on the table " ), the robot must move its camera through the environment and recognize the described object. previous works map language descriptions to a set of fixed object detectors with predetermined noise models, but these approaches are challenging to scale because new detectors need to be made for each object. in this work, we bridge the gap in realistic object search by posing the search problem as a partially observable markov decision process ( pomdp ) where the object detector and visual sensor noise in the observation model is determined by a single deep neural network conditioned on complex language descriptions. we incorporate the neural network ' s outputs into our language - conditioned observation model ( lcom ) to represent dynamically changing sensor noise. with an lcom, any language description of an object can be used to generate an appropriate object detector and noise model, and training an lcom only requires readily available supervised image - caption datasets. we empirically evaluate our method by comparing against a state - of - the - art object search algorithm in simulation, and demonstrate that planning with our observation model yields a significantly higher average task completion rate ( from 0. 46 to 0. 66 ) and more efficient and quicker object search than with a fixed - noise model. we demonstrate our method on a boston dynamics spot robot, enabling it to handle complex natural language object descriptions and efficiently find objects in a room - scale environment.
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arxiv:2309.07276
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supersymmetric ward identity for the low energy effective action in the standard background gauge is derived for { \ it arbitrary } trajectories of supergravitons in matrix theory. in our formalism, the quantum - corrected supersymmetry transformation laws of the supergravitons are directly identified in closed form, which exhibit an intricate interplay between supersymmetry and gauge ( brst ) symmetry. as an application, we explicitly compute the transformation laws for the source - probe configuration at 1 - loop and confirm that supersymmetry fixes the form of the action completely, including the normalization, to the lowest order in the derivative expansion.
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arxiv:hep-th/0003161
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with vodataservice 1. 2, service providers in the virtual observatory ( vo ) have a reasonably straightforward way to declare where in space, time, and spectrum the data within a resource ( i. e., service or data collection ) lie. here, we discuss the the mechanism and design choices, current limitations ( e. g., regarding non - electromagnetic or solar system resources ) as well as ways to overcome them. we also show how users and clients can already run queries against resource coverage using a scheme that is expected to become part of regtap 1. 2 ( or a separate standard ). we conclude with an ardent plea to all resource creators to provide stc metadata - - only wide adoption will make this facility useful.
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arxiv:2007.07519
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we discuss umbral calculus as a method of systematically discretizing linear differential equations while preserving their point symmetries as well as generalized symmetries. the method is then applied to the schr \ " { o } dinger equation in order to obtain a realization of nonrelativistic quantum mechanics in discrete space - time. in this approach a quantum system on a lattice has a symmetry algebra isomorphic to that of the continuous case. moreover, systems that are integrable, superintegrable or exactly solvable preserve these properties in the discrete case.
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arxiv:nlin/0305047
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the number ( ; spelled out as tau ) is a mathematical constant that is the ratio of a circle ' s circumference to its radius. it is approximately equal to 6. 28 and exactly equal to 2π. and π are both circle constants relating the circumference of a circle to its linear dimension : the radius in the case of ; the diameter in the case of π. while π is used almost exclusively in mainstream mathematical education and practice, it has been proposed, most notably by michael hartl in 2010, that should be used instead. hartl and other proponents argue that is the more natural circle constant and its use leads to conceptually simpler and more intuitive mathematical notation. critics have responded that the benefits of using over π are trivial and that given the ubiquity and historical significance of π a change is unlikely to occur. the proposal did not initially gain widespread acceptance in the mathematical community, but awareness of has become more widespread, having been added to several major programming languages and calculators. = = fundamentals = = = = = definition = = = is commonly defined as the ratio of a circle ' s circumference c { \ textstyle { c } } to its radius r { \ textstyle { r } } : τ = c r { \ displaystyle \ tau = { \ frac { c } { r } } } a circle is defined as a closed curve formed by the set of all points in a plane that are a given distance from a fixed point, where the given distance is called the radius. the distance around the circle is the circumference, and the ratio c r { \ textstyle { \ frac { c } { r } } } is constant regardless of the circle ' s size. thus, denotes the fixed relationship between the circumference of any circle and the fundamental defining property of that circle, the radius. = = = units of angle = = = when radians are used as the unit of angular measure there are radians in one full turn of a circle, and the radian angle is aligned with the proportion of a full turn around the circle : τ 8 { \ textstyle { \ frac { \ tau } { 8 } } } rad is an eighth of a turn ; 3 τ 4 { \ textstyle { \ frac { 3 \ tau } { 4 } } } rad is three - quarters of a turn. = = = relationship
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https://en.wikipedia.org/wiki/Tau_(mathematics)
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in this thesis we shall present two logical systems, mp and mp, for the purpose of reasoning about knowledge and effort. these logical systems will be interpreted in a spatial context and therefore, the abstract concepts of knowledge and effort will be defined by concrete mathematical concepts.
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arxiv:cs/0007038
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we perform an analysis in harmonic space of the dark energy survey year 1 data ( des - y1 ) galaxy clustering data using products obtained for the real - space analysis. we test our pipeline with a suite of lognormal simulations, which are used to validate scale cuts in harmonic space as well as to provide a covariance matrix that takes into account the des - y1 mask. we then apply this pipeline to des - y1 data taking into account survey property maps derived for the real - space analysis. we compare with real - space des - y1 results obtained from a similar pipeline. we show that the harmonic space analysis we develop yields results that are compatible with the real - space analysis for the bias parameters. this verification paves the way to performing a harmonic space analysis for the upcoming des - y3 data.
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arxiv:2103.14190
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we will investigate the influence of the inhomogeneity of the universe, especially that of the lema { \ ^ i } tre - tolman - bondi ( ltb ) model, on a gravitationally bound local system such as the solar system. we concentrate on the dynamical perturbation to the planetary motion and derive the leading order effect generated from the ltb model. it will be shown that there appear not only a well - known cosmological effect arisen from the homogeneous and isotropic model, such as the robertson - walker ( rw ) model, but also the additional terms due to the radial inhomogeneity of the ltb model. we will also apply the obtained results to the problem of secular increase in the astronomical unit, reported by krasinsky and brumberg ( 2004 ), and imply that the inhomogeneity of the universe cannot have a significant effect for explaining the observed $ d { \ rm au } / dt = 15 \ pm 4 ~ { \ rm [ m / century ] } $.
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arxiv:1204.3667
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event extraction, the technology that aims to automatically get the structural information from documents, has attracted more and more attention in many fields. most existing works discuss this issue with the token - level multi - label classification framework by distinguishing the tokens as different roles while ignoring the writing styles of documents. the writing style is a special way of content organizing for documents and it is relative fixed in documents with a special field ( e. g. financial, medical documents, etc. ). we argue that the writing style contains important clues for judging the roles for tokens and the ignorance of such patterns might lead to the performance degradation for the existing works. to this end, we model the writing style in documents as a distribution of argument roles, i. e., role - rank distribution, and propose an event extraction model with the role - rank distribution based supervision mechanism to capture this pattern through the supervised training process of an event extraction task. we compare our model with state - of - the - art methods on several real - world datasets. the empirical results show that our approach outperforms other alternatives with the captured patterns. this verifies the writing style contains valuable information that could improve the performance of the event extraction task.
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arxiv:2201.03188
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given a closed, bounded convex set $ \ mathcal { w } \ subset { \ mathbb { r } } ^ d $ with nonempty interior, we consider a control problem in which the state process $ w $ and the control process $ u $ satisfy \ [ w _ t = w _ 0 + \ int _ 0 ^ t \ vartheta ( w _ s ) ds + \ int _ 0 ^ t \ sigma ( w _ s ) dz _ s + gu _ t \ in \ mathcal { w }, \ qquad t \ ge0, \ ] where $ z $ is a standard, multi - dimensional brownian motion, $ \ vartheta, \ sigma \ in c ^ { 0, 1 } ( \ mathcal { w } ) $, $ g $ is a fixed matrix, and $ w _ 0 \ in \ mathcal { w } $. the process $ u $ is locally of bounded variation and has increments in a given closed convex cone $ \ mathcal { u } \ subset { \ mathbb { r } } ^ p $. given $ g \ in c ( \ mathcal { w } ) $, $ \ kappa \ in { \ mathbb { r } } ^ p $, and $ \ alpha > 0 $, consider the objective that is to minimize the cost \ [ j ( w _ 0, u ) \ doteq \ mathbb { e } \ biggl [ \ int _ 0 ^ { \ infty } e ^ { - \ alpha s } g ( w _ s ) ds + \ int _ { [ 0, \ infty ) } e ^ { - \ alpha s } d ( \ kappa \ cdot u _ s ) \ biggr ] \ ] over the admissible controls $ u $. both $ g $ and $ \ kappa \ cdot u $ ( $ u \ in \ mathcal { u } $ ) may take positive and negative values. this paper studies the corresponding dynamic programming equation ( dpe ), a second - order degenerate elliptic partial differential equation of hjb - type with a state constraint boundary condition. under the controllability condition $ g \ mathcal { u } = { \ mathbb { r } } ^ d $ and the finiteness of $ \ mathcal { h } ( q ) = \ sup _ { u \ in \ mathcal { u } _ 1 } \ { - gu \ cd
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arxiv:0711.0641
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solar flares are sudden energy release events in the solar corona, resulting from magnetic reconnection, that accelerates particles and heats the ambient plasma. during a flare, there are often multiple, temporally and spatially separated individual energy release episodes that can be difficult to resolve depending on the observing instrument. we present multi - wavelength imaging and spectroscopy observations of multiple electron acceleration episodes during a goes b1. 7 - class two - ribbon flare on 2012 february 25, observed simultaneously with the karl g. jansky very large array ( vla ) at 1 - - 2 ghz, the reuven ramatay high energy solar spectroscopic imager ( rhessi ) in x - rays, and the solar dynamics observatory in extreme ultraviolet ( euv ). during the initial phase of the flare, five radio bursts were observed. a nonthermal x - ray source was seen co - temporal, but not co - spatial, with the first three radio bursts. their radio spectra are interpreted as optically thick gyrosynchrotron emission. by fitting the radio spectra with a gyrosynchrotron model, we derive the magnetic field strength and nonthermal electron spectral parameters in each acceleration episode. notably, the nonthermal parameters derived from x - rays differ considerably from the nonthermal parameters inferred from the radio. the observations are indicative of multiple, co - temporal acceleration episodes during the impulsive phase of a solar microflare. the x - ray and radio burst sources likely originate from separate electron distributions in different magnetic loops.
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arxiv:2009.14497
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when $ r $ is a non - archimedean real closed field we say that a function $ f \ in r ( \ bar { x } ) $ is finitary at a point $ \ bar { b } \ in r ^ n $ if on some neighborhood of $ \ bar { b } $ the defined values of $ f $ are in the finite part of $ r $. in this note we give a characterization of rational functions which are finitary on a set defined by positivity and finiteness conditions. the main novel ingredient is a proof that ovf - integrality has a natural topological definition, which allows us to apply a known ganzstellensatz for the relevant valuation. we also give some information about the kochen geometry associated with ovf - integrality.
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arxiv:1103.1873
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the influence of graphene on the assembly of intercalated material is studied using low - temperature scanning tunneling microscopy. intercalation of pt under monolayer graphene on pt ( 111 ) induces a substrate reconstruction that is qualitatively different from the lattice rearrangement induced by metal deposition on pt ( 111 ) and, specifically, the homoepitaxy of pt. alkali metals cs and li are used as intercalants for monolayer and bilayer graphene on ru ( 0001 ). atomically resolved topographic data reveal that at elevated alkali metal coverage $ ( 2 \ times 2 ) $ cs and $ ( 1 \ times 1 ) $ li intercalant structures form with respect to the graphene lattice.
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arxiv:1812.04851
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band structure calculations of cro2 carried out in the lsda + u approach reveal a clear picture of the physics behind the metallic ferromagnetic properties. arguments are presented that the metallic ferromagnetic oxide cro2 belongs to a class of materials in which magnetic ordering exists due to double exchange ( in this respect cro2 turns out to be similar to the cmr manganates ). it is concluded that cro2 has small or even negative charge transfer gap which can result in self - doping. certain experiments to check the proposed picture are suggested.
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arxiv:cond-mat/9705091
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plasmon - enhanced raman scattering ( pers ) becomes nonlinear when phonon pumping and phonon - stimulated scattering come into play. it is fundamental to the understanding of pers and its photobleaching behavior. by quantization of the molecular vibration coherent state into phonon number states, we theoretically predict a stepwise dependence of pers intensity on laser power. experimental evidence is presented by measuring a monolayer of malachite green isothiocyanate molecules sandwiched in individual gold nanosphere - plane antennas, under radially polarized laser excitation of sub - microwatt powers.
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arxiv:1601.03324
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the riemann surface for polylogarithms of half - integer index, which has the topology of an infinite dimensional hypercube, is studied in relation to one - dimensional kpz universality in finite volume. known exact results for fluctuations of the kpz height with periodic boundaries are expressed in terms of meromorphic functions on this riemann surface, summed over all the sheets of a covering map to an infinite cylinder. connections to stationary large deviations, particle - hole excitations and kdv solitons are discussed.
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arxiv:1908.08907
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the theory of radiative transfer provides the link between the physical conditions in an astrophysical object and the observable radiation which it emits. thus accurately modelling radiative transfer is often a necessary part of testing theoretical models by comparison with observations. we describe a new radiative transfer code which employs monte carlo methods for the numerical simulation of radiation transport in expanding media. we discuss the application of this code to the calculation of synthetic spectra and light curves for a type ia supernova explosion model and describe the sensitivity of the results to certain approximations made in the simulations.
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arxiv:0911.1549
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this paper examines the assumptions of the derived equivalence between dropout noise injection and $ l _ 2 $ regularisation for logistic regression with negative log loss. we show that the approximation method is based on a divergent taylor expansion, making, subsequent work using this approximation to compare the dropout trained logistic regression model with standard regularisers unfortunately ill - founded to date. moreover, the approximation approach is shown to be invalid using any robust constraints. we show how this finding extends to general neural network topologies that use a cross - entropy prediction layer.
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arxiv:1905.11320
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probing deeper into the existing issues regarding the exit probability ( ep ) in one dimensional dynamical models, we consider several models where the states are represented by ising spins and the information flows inwards. at zero temperature, these systems evolve to either of two absorbing states. the exit probability $ e ( x ) $, which is the probability that the system ends up with all spins up starting with $ x $ fraction of up spins is found to have the general form $ e ( x ) = x ^ \ alpha / \ left [ x ^ \ alpha + ( 1 - x ) ^ \ alpha \ right ] $. the exit probability exponent $ \ alpha $ strongly depends on $ r $, the range of interaction, the symmetry of the model and the induced fluctuation. even in a nearest neighbour model, nonlinear form of ep can be obtained by controlling the fluctuations and for the same range, different models give different results for $ \ alpha $. non - universal behaviour of the exit probability is thus clearly established and the results are compared to existing studies in models with outflow dynamics to distinguish the two dynamical scenarios.
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arxiv:1401.2797
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the gamma - ray binary hess j0632 + 057 has been observed at very - high energies ( e $ > $ 100 gev ) for more than ten years by the major systems of imaging atmospheric cherenkov telescopes. we present a summary of results obtained with the h. e. s. s., magic, and veritas experiments based on roughly 440 h of observations in total. this includes a discussion of an unusually bright tev outburst of hess j0632 + 057 in january 2018. the updated gamma - ray light curve now covers all phases of the orbital period with significant detections in almost all orbital phases. results are discussed in context with simultaneous observations with the x - ray telescope onboard the neil gehrels swift observatory.
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arxiv:1908.03589
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this paper introduces a novel architecture for quantum graph neural networks, which is significantly different from previous approaches found in the literature. the proposed approach produces similar outcomes with respect to previous models but with fewer parameters, resulting in an extremely interpretable architecture rooted in the underlying physics of the problem. the architectural novelties arise from three pivotal aspects. firstly, we employ an embedding updating method that is analogous to classical graph neural networks, therefore bridging the classical - quantum gap. secondly, each layer is devoted to capturing interactions of distinct orders, aligning with the physical properties of the system. lastly, we harness swap gates to emulate the problem ' s inherent symmetry, a novel strategy not found currently in the literature. the obtained results in the considered experiments are encouraging to lay the foundation for continued research in this field.
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arxiv:2408.03427
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deep neural network ( dnn ) based inference at the edge is challenging as these compute and data - intensive algorithms need to be implemented at low cost and low power while meeting the latency constraints of the target applications. sparsity, in both activations and weights inherent to dnns, is a key knob to leverage. in this paper, we present raman, a re - configurable and sparse tinyml accelerator for inference on edge, architected to exploit the sparsity to reduce area ( storage ), power as well as latency. raman can be configured to support a wide range of dnn topologies - consisting of different convolution layer types and a range of layer parameters ( feature - map size and the number of channels ). raman can also be configured to support accuracy vs power / latency tradeoffs using techniques deployed at compile - time and run - time. we present the salient features of the architecture, provide implementation results and compare the same with the state - of - the - art. raman employs novel dataflow inspired by gustavson ' s algorithm that has optimal input activation ( ia ) and output activation ( oa ) reuse to minimize memory access and the overall data movement cost. the dataflow allows raman to locally reduce the partial sum ( psum ) within a processing element array to eliminate the psum writeback traffic. additionally, we suggest a method to reduce peak activation memory by overlapping ia and oa on the same memory space, which can reduce storage requirements by up to 50 %. raman was implemented on a low - power and resource - constrained efinix ti60 fpga with 37. 2k luts and 8. 6k register utilization. raman processes all layers of the mobilenetv1 model at 98. 47 gop / s / w and the ds - cnn model at 79. 68 gop / s / w by leveraging both weight and activation sparsity.
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arxiv:2306.06493
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we revisit the physical effects of discrete $ \ mathbb { z } _ p $ gauge charge on black hole thermodynamics, building on the seminal work of coleman, preskill, and wilczek. realising the discrete theory from the spontaneous breaking of an abelian gauge theory, we consider the two limiting cases of interest, depending on whether the compton wavelength of the massive vector is much smaller or much larger than the size of the black hole - - the so - called thin - and thick - string limits respectively. we find that the qualitative effect of discrete hair on the mass - temperature relationship is the same in both regimes, and similar to that of unbroken $ u ( 1 ) $ charge : namely, a black hole carrying discrete gauge charge is always colder than its uncharged counterpart. in the thick - string limit, our conclusions bring into question some of the results of coleman et al., as we discuss. further, by considering the system to be enclosed within a finite cavity, we argue how the unbroken limit may be smoothly defined, and the unscreened electric field of the standard reissner - nordstrom solution recovered.
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arxiv:1809.03527
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we present serendipitous detections of radio sources at 28. 5 ghz ( 1 cm ), which resulted from our program to image thermal sunyaev - zeldovich ( sz ) effect in 56 galaxy clusters. we find 64 radio sources with fluxes down to 0. 4 mjy, and within 250 arcseconds from the pointing centers. the spectral indices ( s ~ \ nu ^ - \ alpha ) of 54 sources with published low frequency flux densities range from - 0. 6 to 2 with a mean of 0. 77, and a median of 0. 84. extending low frequency surveys of radio sources towards galaxy clusters cl 0016 + 16, abell 665, and abell 2218 to 28. 5 ghz, and selecting sources with 1. 4 ghz flux density greater than 7 mjy to form an unbiased sample, we find a mean spectral index of 0. 71 and a median of 0. 71. we find 4 to 7 times more sources predicted from a low frequency survey in areas without galaxy clusters. this excess cannot be accounted for by gravitational lensing of a background radio population by cluster potentials, indicating most of the detected sources are associated with galaxy clusters. for the cluster abell 2218, the presence of unsubtracted radio sources with 28. 5 ghz flux densities less than 0. 5 mjy, can only contribute to temperature fluctuations at a level of 10 to 25 \ muk. the corresponding error due to radio point source contamination in the hubble constant derived through a combined analysis of 28. 5 ghz sz images and x - ray emission observations ranges from 1 % to 6 %.
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arxiv:astro-ph/9711218
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starting from the quantum - phase - estimate ( qpe ) algorithm, a method is proposed to construct entangled states that describe correlated many - body systems on quantum computers. using operators for which the discrete set of eigenvalues is known, the qpe approach is followed by measurements that serve as projectors on the entangled states. these states can then be used as inputs for further quantum or hybrid quantum - classical processing. when the operator is associated to a symmetry of the hamiltonian, the approach can be seen as a quantum - - computer formulation of symmetry breaking followed by symmetry restoration. the method proposed in this work, called discrete spectra assisted ( dsa ), is applied to superfluid systems. by using the blocking technique adapted to qubits, the full spectra of a pairing hamiltonian is obtained.
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arxiv:2006.06491
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plasma composition measurements are a vital tool for the success of current and future solar missions, but density and temperature insensitive spectroscopic diagnostic ratios are sparse, and their underlying accuracy in determining the magnitude of the first ionization potential ( fip ) effect in the solar atmosphere remains an open question. here we assess the fe viii 185. 213a / ne viii 770. 428a intensity ratio that can be observed as a multi - spacecraft combination between solar orbiter / spice and hinode / eis. we find that it is fairly insensitive to temperature and density in the range of log ( t / k ) = 5. 65 - 6. 05 and is therefore useful, in principle, for analyzing on - orbit euv spectra. we also perform an empirical experiment, using hinode / eis measurements of coronal fan loop temperature distributions weighted by randomnly generated fip bias values, to show that our diagnostic method can provide accurate results as it recovers the input fip bias to within 10 - - 14 %. this is encouraging since it is smaller than the magnitude of variations seen throughout the solar corona. we apply the diagnostic to coordinated observations from 2023 march, and show that the combination of spice and eis allows measurements of the fe / ne fip bias in the regions where the footpoints of the magnetic field connected to solar orbiter are predicted to be located. the results show an increase in fip bias between the main leading polarity and the trailing decayed polarity that broadly agrees with fe / o in - situ measurements from solar orbiter / swa. multi - spacecraft coordinated observations are complex, but this diagnostic also falls within the planned wavebands for solar - c / euvst.
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arxiv:2410.15606
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following fr \ ' enod and sonnendr \ " ucker, we consider the finite larmor radius regime for a plasma submitted to a large magnetic field and take into account both the quasineutrality and the local thermodynamic equilibrium of the electrons. we then rigorously establish the asymptotic gyrokinetic limit of the rescaled and modified vlasov - poisson system in a three - dimensional setting with the help of an averaging lemma.
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arxiv:0812.2528
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borg - type uniqueness theorems for matrix - valued jacobi operators h and supersymmetric dirac difference operators d are proved. more precisely, assuming reflectionless matrix coefficients a, b in the self - adjoint jacobi operator h = as ^ + + a ^ - s ^ - + b ( with s ^ \ pm the right / left shift operators on the lattice z ) and the spectrum of h to be a compact interval [ e _ -, e _ + ], e _ - < e _ +, we prove that a and b are certain multiples of the identity matrix. an analogous result which, however, displays a certain novel nonuniqueness feature, is proved for supersymmetric self - adjoint dirac difference operators d with spectrum given by [ - e _ + ^ { 1 / 2 }, - e _ - ^ { 1 / 2 } ] \ cup [ e _ - ^ { 1 / 2 }, e _ + ^ { 1 / 2 } ], 0 \ leq e _ - < e _ +.
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arxiv:math/0408074
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we show how conway ' s multivariable potential function can be constructed using braids and the reduced gassner representation. the resulting formula is a multivariable generalization of a construction, due to kassel - turaev, of the alexander - conway polynomial in terms of the burau representation. apart from providing an efficient method of computing the potential function, our result also removes the sign ambiguity in the current formulas which relate the multivariable alexander polynomial to the reduced gassner representation. we also relate the distinct definitions of this representation which have appeared in the literature.
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arxiv:1709.03479
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we construct a holographic dark energy model in a braneworld setup that gravity is induced on the brane embedded in a bulk with gauss - bonnet curvature term. we include possible modification of the induced gravity and its coupling with a canonical scalar field on the brane. through a perturbational approach to calculate the effective gravitation constant on the brane, we examine the outcome of this model as a candidate for holographic dark energy.
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arxiv:0912.4802
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quantum trajectory methods can be used for a wide range of open quantum systems to solve the master equation by unraveling the density operator evolution into individual stochastic trajectories in hilbert space. this c + + class library offers a choice of integration algorithms for three important unravelings of the master equation. different physical systems are modeled by different hamiltonians and environment operators. the program achieves flexibility and user friendliness, without sacrificing execution speed, through the way it represents operators and states in hilbert space. primary operators, implemented in the form of simple routines acting on single degrees of freedom, can be used to build up arbitrarily complex operators in product hilbert spaces with arbitrary numbers of components. standard algebraic notation is used to build operators and to perform arithmetic operations on operators and states. states can be represented in a local moving basis, often leading to dramatic savings of computing resources. the state and operator classes are very general and can be used independently of the quantum trajectory algorithms. only a rudimentary knowledge of c + + is required to use this package.
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arxiv:quant-ph/9608004
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the final inspiral phase in the evolution of a compact binary consisting of black holes and / or neutron stars is among the most probable events that a network of ground - based interferometric gravitational wave detectors is likely to observe. gravitational radiation emitted during this phase will have to be dug out of noise by matched - filtering ( correlating ) the detector output with a bank of several $ 10 ^ 5 $ templates, making the computational resources required quite demanding, though not formidable. we propose an interpolation method for evaluating the correlation between template waveforms and the detector output and show that the method is effective in substantially reducing the number of templates required. indeed, the number of templates needed could be a factor $ \ sim 4 $ smaller than required by the usual approach, when the minimal overlap between the template bank and an arbitrary signal ( the so - called { \ it minimal match } ) is 0. 97. the method is amenable to easy implementation, and the various detector projects might benefit by adopting it to reduce the computational costs of inspiraling neutron star and black hole binary search.
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arxiv:gr-qc/0008059
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motivated by recent studies of supersymmetry in higher - dimensional spaces, we discuss the experimental signatures of a superlight gravitino, mass < 0. 001 ev. we concentrate on the process ( e - gamma - > selectronr gravitino ) as a probe of supersymmetry, where a single heavy superpartner and a superlight gravitino are produced. the fact that there is only one heavy superpartner in the final state in this process would require a lower center - of - mass energy for on - shell production compared to conventional pair production. for instance, for a 500 gev machine, we find that a positive signal will be found if the supersymmetry breaking scale is less than about 2 tev. if no positive signal is found, this process puts a bound on the supersymmetry breaking scale.
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arxiv:hep-ph/0108006
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a new perturbation theory is proposed for studying finite - size effects near critical point of the $ \ phi ^ 4 $ model with a one - component order parameter. the new approach is based on the techniques of generating functional and functional derivative with respect to external source field and can be used for temperatures both above and below the critical point of the bulk system. it is shown that this approach is much simpler comparing with available perturbation theories. particularly, this new method avoids renormalization in calculating many physical quantities such as correlation functions etc..
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arxiv:cond-mat/9612076
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we investigate modifications to bayesian optimization for a resource - constrained setting of sequential experimental design where changes to certain design variables of the search space incur a switching cost. this models the scenario where there is a trade - off between evaluating more while maintaining the same setup, or switching and restricting the number of possible evaluations due to the incurred cost. we adapt two process - constrained batch algorithms to this sequential problem formulation, and propose two new methods : one cost - aware and one cost - ignorant. we validate and compare the algorithms using a set of 7 scalable test functions in different dimensionalities and switching - cost settings for 30 total configurations. our proposed cost - aware hyperparameter - free algorithm yields comparable results to tuned process - constrained algorithms in all settings we considered, suggesting some degree of robustness to varying landscape features and cost trade - offs. this method starts to outperform the other algorithms with increasing switching - cost. our work broadens out from other recent bayesian optimization studies in resource - constrained settings that consider a batch setting only. while the contributions of this work are relevant to the general class of resource - constrained problems, they are particularly relevant to problems where adaptability to varying resource availability is of high importance
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arxiv:2405.08973
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##s " may refer to a real - valued function of a real variable whose domain is a proper subset of the real numbers, typically a subset that contains a non - empty open interval. such a function is then called a partial function. a function f on a set s means a function from the domain s, without specifying a codomain. however, some authors use it as shorthand for saying that the function is f : s → s. = = = formal definition = = = the above definition of a function is essentially that of the founders of calculus, leibniz, newton and euler. however, it cannot be formalized, since there is no mathematical definition of an " assignment ". it is only at the end of the 19th century that the first formal definition of a function could be provided, in terms of set theory. this set - theoretic definition is based on the fact that a function establishes a relation between the elements of the domain and some ( possibly all ) elements of the codomain. mathematically, a binary relation between two sets x and y is a subset of the set of all ordered pairs ( x, y ) { \ displaystyle ( x, y ) } such that x ∈ x { \ displaystyle x \ in x } and y ∈ y. { \ displaystyle y \ in y. } the set of all these pairs is called the cartesian product of x and y and denoted x × y. { \ displaystyle x \ times y. } thus, the above definition may be formalized as follows. a function with domain x and codomain y is a binary relation r between x and y that satisfies the two following conditions : for every x { \ displaystyle x } in x { \ displaystyle x } there exists y { \ displaystyle y } in y { \ displaystyle y } such that ( x, y ) ∈ r. { \ displaystyle ( x, y ) \ in r. } if ( x, y ) ∈ r { \ displaystyle ( x, y ) \ in r } and ( x, z ) ∈ r, { \ displaystyle ( x, z ) \ in r, } then y = z. { \ displaystyle y = z. } this definition may be rewritten more formally, without referring explicitly to the concept of a relation, but using more notation ( including set - builder notation ) : a function is formed by three sets, the domain x, { \ displaystyle x, }
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https://en.wikipedia.org/wiki/Function_(mathematics)
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multimodal large language models ( mllms ) have gained significant traction for their ability to process diverse input data types and generate coherent, contextually relevant outputs across various applications. while supervised fine - tuning ( sft ) has been the predominant approach to enhance mllm capabilities in task - specific optimization, it often falls short in fostering crucial generalized reasoning abilities. although reinforcement learning ( rl ) holds great promise in overcoming these limitations, it encounters two significant challenges : ( 1 ) its generalized capacities in multimodal tasks remain largely unexplored, and ( 2 ) its training constraints, including the constant kullback - leibler divergence or the clamp strategy, often result in suboptimal bottlenecks. to address these challenges, we propose othink - mr1, an advanced mllm equipped with profound comprehension and reasoning capabilities across multimodal tasks. specifically, we introduce group relative policy optimization with a dynamic kullback - leibler strategy ( grpo - d ), which markedly enhances reinforcement learning ( rl ) performance. for qwen2 - vl - 2b - instruct, grpo - d achieves a relative improvement of more than 5. 72 % over sft and more than 13. 59 % over grpo in same - task evaluation on two adapted datasets. furthermore, grpo - d demonstrates remarkable cross - task generalization capabilities, with an average relative improvement of more than 61. 63 % over sft in cross - task evaluation. these results highlight that the mllm trained with grpo - d on one multimodal task can be effectively transferred to another task, underscoring the superior generalized reasoning capabilities of our proposed othink - mr1 model.
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arxiv:2503.16081
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v838 mon is marking one of the most mysterious stellar outbursts on record. the spectral energy distribution of the progenitor resembles an under - luminous f main sequence star ( at v = 15. 6 mag ), that erupted into a cool supergiant following a complex and multi - maxima lightcurve ( peaking at v = 6. 7 mag ). the outburst spectrum show baii, lii and lines of several s - elements, with wide p - cyg profiles and a moderate and retracing emission in the balmer lines. a light - echo discovered expanding around the object helped to constrain the distance ( d = 790 + / - 30 pc ), providing m _ v = + 4. 45 in quiescence and m _ v = - 4. 35 at optical maximum ( somewhat dependent on the still uncertain e ( b - v ) = 0. 5 reddening ). the general outburst trend is toward lower temperatures and larger luminosities, and continuing so at the time of writing. the object properties conflict with a classification within already existing categories : the progenitor was not on a post - agb track and thus the similarities with the born - again agb stars fg sge, v605 aql and sakurai ' s object are limited to the cool giant spectrum at maximum ; the cool spectrum, the moderate wind velocity ( 500 km / sec and progressively reducing ) and the monotonic decreasing of the low ionization condition argues against a classical nova scenario. the closest similarity is with a star that erupted into an m - type supergiant discovered in m31 by rich et al. ( 1989 ), that became however much brighter by peaking at m _ v = - 9. 95, and with v4332 sgr that too erupted into an m - type giant ( martini et al. 1999 ) and that attained a lower luminosity, closer to that of v838 mon. m31 - redvar, v4332 sgr and v838 mon could be manifestations of the same and new class of astronomical objects.
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arxiv:astro-ph/0205288
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a path - following control algorithm enables a system ' s trajectories under its guidance to converge to and evolve along a given geometric desired path. there exist various such algorithms, but many of them can only guarantee local convergence to the desired path in its neighborhood. in contrast, the control algorithms using a well - designed guiding vector field can ensure almost global convergence of trajectories to the desired path ; here, " almost " means that in some cases, a measure - zero set of trajectories converge to the singular set where the vector field becomes zero ( with all other trajectories converging to the desired path ). in this paper, we first generalize the guiding vector field from the euclidean space to a general smooth riemannian manifold. this generalization can deal with path - following in some abstract configuration space ( such as robot arm joint space ). then we show several theoretical results from a topological viewpoint. specifically, we are motivated by the observation that singular points of the guiding vector field exist in many examples where the desired path is homeomorphic to the unit circle, but it is unknown whether the existence of singular points always holds in general ( i. e., is inherent in the topology of the desired path ). in the $ n $ - dimensional euclidean space, we provide an affirmative answer, and conclude that it is not possible to guarantee global convergence to desired paths that are homeomorphic to the unit circle. furthermore, we show that there always exist \ emph { non - path - converging trajectories } ( i. e., trajectories that do not converge to the desired path ) starting from the boundary of a ball containing the desired path in an $ n $ - dimensional euclidean space where $ n \ ge 3 $. examples are provided to illustrate the theoretical results.
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arxiv:2202.03343
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we present hume, a simple model - agnostic framework for inferring human labeling of a given dataset without any external supervision. the key insight behind our approach is that classes defined by many human labelings are linearly separable regardless of the representation space used to represent a dataset. hume utilizes this insight to guide the search over all possible labelings of a dataset to discover an underlying human labeling. we show that the proposed optimization objective is strikingly well - correlated with the ground truth labeling of the dataset. in effect, we only train linear classifiers on top of pretrained representations that remain fixed during training, making our framework compatible with any large pretrained and self - supervised model. despite its simplicity, hume outperforms a supervised linear classifier on top of self - supervised representations on the stl - 10 dataset by a large margin and achieves comparable performance on the cifar - 10 dataset. compared to the existing unsupervised baselines, hume achieves state - of - the - art performance on four benchmark image classification datasets including the large - scale imagenet - 1000 dataset. altogether, our work provides a fundamentally new view to tackle unsupervised learning by searching for consistent labelings between different representation spaces.
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arxiv:2311.02940
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multi - modal deep learning techniques for matching free - form text with music have shown promising results in the field of music information retrieval ( mir ). prior work is often based on large proprietary data while publicly available datasets are few and small in size. in this study, we present wikimute, a new and open dataset containing rich semantic descriptions of music. the data is sourced from wikipedia ' s rich catalogue of articles covering musical works. using a dedicated text - mining pipeline, we extract both long and short - form descriptions covering a wide range of topics related to music content such as genre, style, mood, instrumentation, and tempo. to show the use of this data, we train a model that jointly learns text and audio representations and performs cross - modal retrieval. the model is evaluated on two tasks : tag - based music retrieval and music auto - tagging. the results show that while our approach has state - of - the - art performance on multiple tasks, but still observe a difference in performance depending on the data used for training.
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arxiv:2312.09207
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we investigate under which assumptions the flow associated to autonomous planar vector fields inherits the sobolev or bv regularity of the vector field. we consider nearly incompressible and divergence - free vector fields, taking advantage in both cases of the underlying hamiltonian structure. finally we provide an example of an autonomous planar sobolev divergence - free vector field, such that the corresponding regular lagrangian flow has no bounded variation.
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arxiv:2101.07871
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weitzman introduced pandora ' s box problem as a mathematical model of sequential search with inspection costs, in which a searcher is allowed to select a prize from one of $ n $ alternatives. several decades later, doval introduced a close version of the problem, where the searcher does not need to incur the inspection cost of an alternative, and can select it uninspected. unlike the original problem, the optimal solution to the nonobligatory inspection variant is proved to need adaptivity, and by recent work of [ fll22 ], finding the optimal solution is np - hard. our first main result is a structural characterization of the optimal policy : we show there exists an optimal policy that follows only two different pre - determined orders of inspection, and transitions from one to the other at most once. our second main result is a polynomial time approximation scheme ( ptas ). our proof involves a novel reduction to a framework developed by [ flx18 ], utilizing our optimal two - phase structure. furthermore, we show pandora ' s problem with nonobligatory inspection belongs to class np, which by using the hardness result of [ fll22 ], settles the computational complexity class of the problem. finally, we provide a tight 0. 8 approximation and a novel proof for committing policies [ bk19 ] ( informally, the set of nonadaptive policies ) for general classes of distributions, which was previously shown only for discrete and finite distributions [ gms08 ].
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arxiv:2212.01524
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we show that, with the exception of the words $ a ^ 2ba ^ 2 $ and $ b ^ 2ab ^ 2 $, all ( finite or infinite ) binary patterns in the prouhet - thue - morse sequence can actually be found in that sequence as segments ( up to exchange of letters in the infinite case ). this result was previously attributed to unpublished work by d. guaiana and may also be derived from publications of a. shur only available in russian. we also identify the ( finitely many ) finite binary patterns that appear non trivially, in the sense that they are obtained by applying an endomorphism that does not map the set of all segments of the sequence into itself.
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arxiv:1904.07137
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a method to efficiently and quantitatively study the delivery of a pesticide - surfactant formulation in water solution over plants leaves is presented. instead of measuring the contact angle, the surface of the leaves wet area is used as key parameter. to this goal, a deep learning model has been trained and tested, to automatically measure the surface of area wet with water solution over cucumber leaves, processing the frames of video footage. we have individuated an existing deep learning model, reported in literature for other applications, and we have applied it to this different task. we present the measurement technique, some details of the deep learning model, its training procedure and its image segmentation performance. finally, we report the results of the wet areas surface measurement as a function of the concentration of a surfactant in the pesticide solution.
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arxiv:2401.08593
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detailed population maps play an important role in diverse fields ranging from humanitarian action to urban planning. generating such maps in a timely and scalable manner presents a challenge, especially in data - scarce regions. to address it we have developed popcorn, a population mapping method whose only inputs are free, globally available satellite images from sentinel - 1 and sentinel - 2 ; and a small number of aggregate population counts over coarse census districts for calibration. despite the minimal data requirements our approach surpasses the mapping accuracy of existing schemes, including several that rely on building footprints derived from high - resolution imagery. e. g., we were able to produce population maps for rwanda with 100m gsd based on less than 400 regional census counts. in kigali, those maps reach an r ^ 2 score of 66 % w. r. t. a ground truth reference map, with an average error of only about 10 inhabitants / ha. conveniently, popcorn retrieves explicit maps of built - up areas and of local building occupancy rates, making the mapping process interpretable and offering additional insights, for instance about the distribution of built - up, but unpopulated areas, e. g., industrial warehouses. moreover, we find that, once trained, the model can be applied repeatedly to track population changes ; and that it can be transferred to geographically similar regions, e. g., from uganda to rwanda ). with our work we aim to democratize access to up - to - date and high - resolution population maps, recognizing that some regions faced with particularly strong population dynamics may lack the resources for costly micro - census campaigns.
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arxiv:2311.14006
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in this work, we describe examples for calculating the 1 - d circular convolution of signals represented by 3 - qubit superpositions. the case is considered, when the discrete fourier transform of one of the signals is known and calculated in advance and only the qft of another signal is calculated. the frequency characteristics of many linear time - invariant systems and filters are well known. therefore, the considered method of convolution can be used for these systems in quantum computation. the ideal low pass and high pass filters are considered and quantum schemes for convolution are presented. the method of the fourier transform is used with one addition qubit to prepare the quantum superposition for the inverse quantum fourier transform.
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arxiv:2205.05727
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the 3x + 1 conjecture asserts that the t - orbit of every positive integer contains 1, where t maps x \ mapsto x / 2 for x even and x \ mapsto ( 3x + 1 ) / 2 for x odd. a set s of positive integers is sufficient if the orbit of each positive integer intersects the orbit of some member of s. in a previous paper it was shown that every arithmetic sequence is sufficient. in this paper we further investigate the concept of sufficiency. we construct sufficient sets of arbitrarily low asymptotic density in the natural numbers. we determine the structure of the groups generated by the maps x \ mapsto x / 2 and x \ mapsto ( 3x + 1 ) / 2 modulo b for b relatively prime to 6, and study the action of these groups on the directed graph associated to the 3x + 1 dynamical system. from this we obtain information about the distribution of arithmetic sequences and obtain surprising new results about certain arithmetic sequences. for example, we show that the forward t - orbit of every positive integer contains an element congruent to 2 mod 9, and every non - trivial cycle and divergent orbit contains an element congruent to 20 mod 27. we generalize these results to find many other sets that are strongly sufficient in this way. finally, we show that the 3x + 1 digraph exhibits a surprising and beautiful self - duality modulo 2 ^ n for any n, and prove that it does not have this property for any other modulus. we then use deeper previous results to construct additional families of nontrivial strongly sufficient sets by showing that for any k < n, one can " fold " the digraph modulo 2 ^ n onto the digraph modulo 2 ^ k in a natural way.
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arxiv:1204.3904
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we present an elegant and effective approach for addressing limitations in existing multi - label classification models by incorporating interaction matching, a concept shown to be useful for ad - hoc search result ranking. by performing soft n - gram interaction matching, we match labels with natural language descriptions ( which are common to have in most multi - labeling tasks ). our approach can be used to enhance existing multi - label classification approaches, which are biased toward frequently - occurring labels. we evaluate our approach on two challenging tasks : automatic medical coding of clinical notes and automatic labeling of entities from software tutorial text. our results show that our method can yield up to an 11 % relative improvement in macro performance, with most of the gains stemming labels that appear infrequently in the training set ( i. e., the long tail of labels ).
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arxiv:2005.08805
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distributed ledger technologies have gained significant attention and adoption in recent years. despite various security features distributed ledger technology provides, they are vulnerable to different and new malicious attacks, such as selfish mining and sybil attacks. while such vulnerabilities have been investigated, detecting and discovering appropriate countermeasures still need to be reported. cybersecurity knowledge is limited and fragmented in this domain, while distributed ledger technology usage grows daily. thus, research focusing on overcoming potential attacks on distributed ledgers is required. this study aims to raise awareness of the cybersecurity of distributed ledger technology by designing a security risk assessment method for distributed ledger technology applications. we have developed a database with possible security threats and known attacks on distributed ledger technologies to accompany the method, including sets of countermeasures. we employed a semi - systematic literature review combined with method engineering to develop a method that organizations can use to assess their cybersecurity risk for distributed ledger applications. the method has subsequently been evaluated in three case studies, which show that the method helps to effectively conduct security risk assessments for distributed ledger applications in these organizations.
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arxiv:2401.12358
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we show that if $ p > 1 $ every subspace of $ \ ell _ p ( \ gamma ) $ is an $ \ ell _ p $ - sum of separable subspaces of $ \ ell _ p $, and we provide examples of subspaces of $ \ ell _ p ( \ gamma ) $ for $ 0 < p \ leq 1 $ that are not even isomorphic to any $ \ ell _ p $ - sum of separable spaces, notably the kernel of any quotient map $ \ ell _ p ( \ gamma ) \ to l _ 1 ( 2 ^ { \ gamma } ) $ with $ \ gamma $ uncountable. we involve the separable complementation property ( scp ) and the separable extension property ( sep ), showing that if $ x $ is a banach space of density character $ \ aleph _ 1 $ with the scp then the kernel of any quotient map $ \ ell _ p ( \ gamma ) \ to x $ is a complemented subspace of a space with the scp and, consequently, has the sep.
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arxiv:2410.16886
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we present a systematic small - correlation expansion to solve the inverse ising problem : find a set of couplings and fields corresponding to a given set of correlations and magnetizations. couplings are calculated up to the third order in the correlations for generic magnetizations, and to the seventh order in the case of zero magnetizations ; in addition we show how to sum some useful classes of diagrams exactly. the resulting expansion outperforms existing algorithms on the sherrington - kirkpatrick spin - glass model.
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arxiv:0811.3574
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masala - chai is a fully automated framework leveraging large language models ( llms ) to generate simulation programs with integrated circuit emphasis ( spice ) netlists. it addresses a long - standing challenge in circuit design automation : automating netlist generation for analog circuits. automating this workflow could accelerate the creation of fine - tuned llms for analog circuit design and verification. in this work, we identify key challenges in automated netlist generation and evaluate multimodal capabilities of state - of - the - art llms, particularly gpt - 4, in addressing them. we propose a three - step workflow to overcome existing limitations : labeling analog circuits, prompt tuning, and netlist verification. this approach enables end - to - end spice netlist generation from circuit schematic images, tackling the persistent challenge of accurate netlist generation. we utilize masala - chai to collect a corpus of 7, 500 schematics that span varying complexities in 10 textbooks and benchmark various open source and proprietary llms. models fine - tuned on masala - chai when used in llm - agentic frameworks such as analogcoder achieve a notable 46 % improvement in pass @ 1 scores. we open - source our dataset and code for community - driven development.
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arxiv:2411.14299
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estimating vaccination uptake is an integral part of ensuring public health. it was recently shown that vaccination uptake can be estimated automatically from web data, instead of slowly collected clinical records or population surveys. all prior work in this area assumes that features of vaccination uptake collected from the web are temporally regular. we present the first ever method to remove this assumption from vaccination uptake estimation : our method dynamically adapts to temporal fluctuations in time series web data used to estimate vaccination uptake. we show our method to outperform the state of the art compared to competitive baselines that use not only web data but also curated clinical data. this performance improvement is more pronounced for vaccines whose uptake has been irregular due to negative media attention ( hpv - 1 and hpv - 2 ), problems in vaccine supply ( ditekipol ), and targeted at children of 12 years old ( whose vaccination is more irregular compared to younger children ).
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arxiv:1702.07326
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the flavor protection in composite higgs models with partial compositeness is known to be insufficient. we explore the possibility to alleviate the tension with cp odd observables by assuming that flavor or cp are symmetries of the composite sector, broken by the coupling to standard model fields. one realization is that the composite sector has a flavor symmetry su ( 3 ) or su ( 3 ) _ u x su ( 3 ) _ d which allows us to realize minimal flavor violation. we show how to avoid the previously problematic tension between a flavor symmetric composite sector and electro - weak precision tests. some of the light quarks are substantially or even fully composite with striking signals at the lhc. we discuss the constraints from recent dijet mass measurements and give an outlook on the discovery potential. we also present a different protection mechanism where we separate the generation of flavor hierarchies and the origin of cp violation. this can eliminate or safely reduce unwanted cp violating effects, realizing effectively " minimal cp violation " and is compatible with a dynamical generation of flavor at low scales.
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arxiv:1106.6357
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in this paper, we introduce a zero - shot voice transfer ( vt ) module that can be seamlessly integrated into a multi - lingual text - to - speech ( tts ) system to transfer an individual ' s voice across languages. our proposed vt module comprises a speaker - encoder that processes reference speech, a bottleneck layer, and residual adapters, connected to preexisting tts layers. we compare the performance of various configurations of these components and report mean opinion score ( mos ) and speaker similarity across languages. using a single english reference speech per speaker, we achieve an average voice transfer similarity score of 73 % across nine target languages. vocal characteristics contribute significantly to the construction and perception of individual identity. the loss of one ' s voice, due to physical or neurological conditions, can lead to a profound sense of loss, impacting one ' s core identity. as a case study, we demonstrate that our approach can not only transfer typical speech but also restore the voices of individuals with dysarthria, even when only atypical speech samples are available - a valuable utility for those who have never had typical speech or banked their voice. cross - lingual typical audio samples, plus videos demonstrating voice restoration for dysarthric speakers are available here ( google. github. io / tacotron / publications / zero _ shot _ voice _ transfer ).
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arxiv:2409.13910
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we give a brief overview of black - hole solutions in four - dimensional supergravity theories and their extremal and supersymmetric limits. we also address problems like cosmic censorship and no - hair theorems in supergravity theories. while supergravity by itself seems not to be enough to enforce cosmic censorship and absence of primary scalar hair, superstring theory may be.
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arxiv:hep-th/9705095
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an isolated complex surface singularity induces a canonical contact structure on its link. in this paper, we initiate the study of the existence problem of stein cobordisms between these contact structures depending on the properties of singularities. as a first step we construct an explicit stein cobordism from any contact 3 - manifold to the canonical contact structure of a proper almost rational singularity introduced by nemethi. we also show that the construction cannot always work in the reverse direction : in fact the u - filtration depth of contact ozsvath - szabo invariant obstructs the existence of a stein cobordism from a proper almost rational singularity to a rational one. along the way, we detect the contact ozsvath - szabo invariants of those contact structures fillable by a ar plumbing graph, generalizing an earlier work of the first author.
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arxiv:1702.06371
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cities generate gains from interaction, but citizens often experience segregation as they move around the urban environment. using gps location data, we identify four distinct patterns of experienced segregation across us cities. most common are affluent or poor neighborhoods where visitors lack diversity and residents have limited exposure to diversity elsewhere. less frequent are majority - minority areas where residents must travel for diverse encounters, and wealthy urban zones with diverse visitors but where locals sort into homogeneous amenities. by clustering areas with similar mobility signatures, we uncover rings around cities and internal pockets where intergroup interaction is limited. using a decision tree, we show that demography and location interact to create these zones. our findings, persistent across time and prevalent across us cities, highlight the importance of considering both who is mixing and where in urban environments. understanding the mesoscopic patterns that define experienced segregation in america illuminates neighborhood advantage and disadvantage, enabling interventions to foster economic opportunity and urban dynamism.
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arxiv:2407.12612
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one of the potential applications of a quantum computer is solving quantum chemical systems. it is known that one of the fastest ways to obtain somewhat accurate solutions classically is to use approximations of density functional theory. we demonstrate a general method for obtaining the exact functional as a machine learned model from a sufficiently powerful quantum computer. only existing assumptions for the current feasibility of solutions on the quantum computer are used. several known algorithms including quantum phase estimation, quantum amplitude estimation, and quantum gradient methods are used to train a machine learned model. one advantage of this combination of algorithms is that the quantum wavefunction does not need to be completely re - prepared at each step, lowering a sizable pre - factor. using the assumptions for solutions of the ground - state algorithms on a quantum computer, we demonstrate that finding the kohn - sham potential is not necessarily more difficult than the ground state density. once constructed, a classical user can use the resulting machine learned functional to solve for the ground state of a system self - consistently, provided the machine learned approximation is accurate enough for the input system. it is also demonstrated how the classical user can access commonly used time - and temperature - dependent approximations from the ground state model. minor modifications to the algorithm can learn other types of functional theories including exact time - and temperature - dependence. several other algorithms - - including quantum machine learning - - are demonstrated to be impractical in the general case for this problem.
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arxiv:2008.05592
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the paper studies possible functional analogs of classical problems from convex geometry. in particular, we provide some bounds in the functional shephard, busemann - petty, and milman problems generalizing known bounds in this problems for convex sets.
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arxiv:2208.13308
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we discuss the constraints induced by the algebra of the poincare ' generators on non - relativistic effective field theories. in the first part we derive some relations among the matching coefficients of the hqet ( and nrqcd ), which have been formerly obtained by use of reparametrization invariance. in the second part we obtain new constraints on the matching coefficients of pnrqcd.
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arxiv:hep-ph/0306107
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compared to general quantum states, the sparse states arise more frequently in the field of quantum computation. in this work, we consider the preparation for $ n $ - qubit sparse quantum states with $ s $ non - zero amplitudes and propose two algorithms. the first algorithm uses $ o ( ns / \ log n + n ) $ gates, improving upon previous methods by $ o ( \ log n ) $. we further establish a matching lower bound for any algorithm which is not amplitude - aware and employs at most $ \ operatorname { poly } ( n ) $ ancillary qubits. the second algorithm is tailored for binary strings that exhibit a short hamiltonian path. an application is the preparation of $ u ( 1 ) $ - invariant state with $ k $ down - spins in a chain of length $ n $, including bethe states, for which our algorithm constructs a circuit of size $ o \ left ( \ binom { n } { k } \ log n \ right ) $. this surpasses previous results by $ o ( n / \ log n ) $ and is close to the lower bound $ o \ left ( \ binom { n } { k } \ right ) $. both the two algorithms shrink the existing gap theoretically and provide increasing advantages numerically.
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arxiv:2404.05147
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we study the mean - field approximation of quantum electrodynamics, by means of a thermodynamic limit. the qed hamiltonian is written in coulomb gauge and does not contain any normal - ordering or choice of bare electron / positron subspaces. neglecting photons, we define properly this hamiltonian in a finite box $ [ - l / 2 ; l / 2 ) ^ 3 $, with periodic boundary conditions and an ultraviolet cut - off $ \ lambda $. we then study the limit of the ground state ( i. e. the vacuum ) energy and of the minimizers as $ l $ goes to infinity, in the hartree - fock approximation. in case with no external field, we prove that the energy per volume converges and obtain in the limit a translation - invariant projector describing the free hartree - fock vacuum. we also define the energy per unit volume of translation - invariant states and prove that the free vacuum is the unique minimizer of this energy. in the presence of an external field, we prove that the difference between the minimum energy and the energy of the free vacuum converges as $ l $ goes to infinity. we obtain in the limit the so - called bogoliubov - dirac - fock functional. the hartree - fock ( polarized ) vacuum is a hilbert - schmidt perturbation of the free vacuum and it minimizes the bogoliubov - dirac - fock energy.
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arxiv:math-ph/0503075
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de haas - van alphen ( dhva ) and shubnikov - de haas ( sdh ) oscillations of the organic metal $ \ theta $ - ( bets ) 4 cobr 4 ( c 6 h 4 cl 2 ) are studied in magnetic fields of up to 55 t at liquid helium temperatures. in line with fermi surfaces ( fs ) illustrating the linear chain of coupled orbits, the observed fourier components are linear combinations of the frequencies linked to the two basic orbits $ \ alpha $ and $ \ beta $, which have small effective masses compared to other organic metals with the same fs topology. analytical formulas based on a second order development of the free energy within the canonical ensemble, not only account for the field and temperature dependence of the dhva amplitudes but also for their relative values. in addition, strongly non - lifshitz - kosevich behaviours are quantitatively interpreted. in contrast, shubnikov - de haas oscillations are not accounted for by this model. short title : quantum oscillations of $ \ theta $ - ( bets ) 4 cobr 4 ( c 6 h 4 cl 2 )
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arxiv:1702.02818
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spin dynamics in low dimensional magnetic systems has been of fundamental importance for a long time and has currently received an impetus owing to the emerging field of nanoelectronics. knowledge of the spin wave lifetimes, in particular, can be favorable for future potential applications. we investigate the low - temperature spin wave excitations in two - dimensional disordered ferromagnetic systems, with a particular focus on the long wavelength magnon lifetimes. a semi - analytical green ' s functions based approach is used to determine the dynamical spectral functions, for different magnetic impurity concentrations, from which the intrinsic linewidth is extracted. we obtain an unambiguous $ q ^ 4 $ scaling of the magnon linewidth which is ascribed to the disorder induced damping of the spin waves, thereby settling a longstanding unresolved issue on the wave - vector dependence. our findings are also in good agreement with previous theoretical studies on heisenberg ferromagnets. additionally, we demonstrate the futility of using the low moments associated with the spectral densities to evaluate the magnon dispersions and lifetimes.
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arxiv:1411.3876
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unsupervised video - based surgical instrument segmentation has the potential to accelerate the adoption of robot - assisted procedures by reducing the reliance on manual annotations. however, the generally low quality of optical flow in endoscopic footage poses a great challenge for unsupervised methods that rely heavily on motion cues. to overcome this limitation, we propose a novel approach that pinpoints motion boundaries, regions with abrupt flow changes, while selectively discarding frames with globally low - quality flow and adapting to varying motion patterns. experiments on the endovis2017 vos and endovis2017 challenge datasets show that our method achieves mean intersection - over - union ( miou ) scores of 0. 75 and 0. 72, respectively, effectively alleviating the constraints imposed by suboptimal optical flow. this enables a more scalable and robust surgical instrument segmentation solution in clinical settings. the code will be publicly released.
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arxiv:2403.10039
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in this article, to each generic real meromorphic function ( i. e., having only simple branch points in the appropriate sense ) we associate a certain combinatorial gadget which we call the park of a function. we show that the park determines the topological type of the generic real meromorphic function and that the set of all parks is in $ 1 - 1 $ - correspondence with the set of all connected components in the space of generic real meromorphic functions. for any of the above components, we introduce and calculate the corresponding hurwitz number. finally as a consequence of our results we determine the topological types of real meromorphic functions from monodromy of orbifold coverings.
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arxiv:1609.05755
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aims : to investigate magnetic reconnection rates during the coalescence of two current loops in the solar chromosphere, by altering the neutral - hydrogen to proton density ratio, ioniziation / recombination coefficients, collision frequency and relative helicity of the loops. methods : 2. 5d numerical simulations of the chromosphere were conducted using a newly developed two - fluid ( ion - neutral ) numerical code. developed from the artificial wind scheme, the numerical code includes the effects of ion - neutral collisions, ionization / recombination, thermal / resistive diffusivity and collisional / resistive heating. results : it was found that the rates of magnetic reconnection strongly depend on the neutral - hydrogen to proton density ratio ; increasing the density ratio by a thousand - fold decreased the rate of magnetic reconnection by twenty - fold. this result implies that magnetic reconnection proceeds significantly faster in the upper chromosphere, where the density of ions ( protons ) and neutral - hydrogen is comparable, than in the lower chromosphere where the density of neutral - hydrogen is over a thousand times the ion density. the inclusion of ionization / recombination, an important physics effect in the chromosphere, increases the total reconnected magnetic flux, but does not alter the rate of magnetic reconnection. reductions in the ion - neutral collision frequency, result in small increases to the rates of magnetic reconnection. the relative helicity of the two current loops was not observed to have any significant effect on the rates of magnetic reconnection. conclusions : the magnetic reconnection rates of coalescing current loops are strongly affected by the inclusion of neutral - hydrogen particles.
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arxiv:0804.2086
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the main source of information regarding ancient mesopotamian history and culture are clay cuneiform tablets. despite being an invaluable resource, many tablets are fragmented leading to missing information. currently these missing parts are manually completed by experts. in this work we investigate the possibility of assisting scholars and even automatically completing the breaks in ancient akkadian texts from achaemenid period babylonia by modelling the language using recurrent neural networks.
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arxiv:2003.01912
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we report a systematic study on edelstein magnetoresistance ( edelstein mr ) in co25fe75 / cu / bi2o3 heterostructures with a strong spin - orbit interaction at the cu / bi2o3 interface. we succeed in observing a significant dependence of the edelstein mr on both cu layer thickness and temperature, and also develop a general analytical model considering distinct bulk and interface contributions on spin relaxation. our analysis, based on the above model, quantitatively illustrates a unique property of the spin transport near the rashba interface, revealing a prominent role of the spin relaxation process by determining the ratios of the spin relaxation inside and outside the interface. we further find the characteristic spin transport is unaffected by temperature. our results provide an essential tool for exploring the transport in a system with spin - momentum - locked two - dimensional states.
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arxiv:1710.06058
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we construct the first known examples of compact pseudo - riemannian manifolds having an essential group of conformal transformations, and which are not conformally flat. our examples cover all types $ ( p, q ) $, with $ 2 \ leq p \ leq q $.
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arxiv:1211.0635
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we explore the dirac spin liquid ( dsl ) as a candidate for the ground state of the mott insulating phase of fermions with six flavors on the kagome lattice, particularly focusing on realizations using $ ^ { 173 } $ yb atoms in optical lattices. using mean - field theory and variational monte carlo ( vmc ) simulations, we confirm the stability of the dsl against local perturbations of the dirac spin liquid ansatz within a 12 - site unit cell and against small second - nearest neighbor and ring exchange interactions. to characterize the dsl, we calculate the static and dynamic structure factor of the gutzwiller projected wavefunction and compare it with mean - field calculations. the static structure factor shows triangular - shaped plateaus around the $ k $ points in the extended brillouin zone, with small peaks at the corners of these plateaus. the dynamical structure factor consists of a gapless continuum of fractionalized excitations. our study also presents several complementary results, including bounds for the ground state energy, methods for calculating three - site ring exchange expectations in the projective mean field, the boundary of ferromagnetic states, and the non - topological nature of flat bands in the dsl band structure.
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arxiv:2407.09713
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we study both divergence and non - divergence form parabolic and elliptic equations in the half space $ \ { x _ d > 0 \ } $ whose coefficients are the product of $ x _ d ^ \ alpha $ and uniformly nondegenerate bounded measurable matrix - valued functions, where $ \ alpha \ in ( - 1, \ infty ) $. as such, the coefficients are singular or degenerate near the boundary of the half space. for equations with the conormal or neumann boundary condition, we prove the existence, uniqueness, and regularity of solutions in weighted sobolev spaces and mixed - norm weighted sobolev spaces when the coefficients are only measurable in the $ x _ d $ direction and have small mean oscillation in the other directions in small cylinders. our results are new even in the special case when the coefficients are constants, and they are reduced to the classical results when $ \ alpha = 0 $
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arxiv:2007.04385
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have evolved from the earliest emergence of life to present day. earth formed about 4. 5 billion years ago and all life on earth, both living and extinct, descended from a last universal common ancestor that lived about 3. 5 billion years ago. geologists have developed a geologic time scale that divides the history of the earth into major divisions, starting with four eons ( hadean, archean, proterozoic, and phanerozoic ), the first three of which are collectively known as the precambrian, which lasted approximately 4 billion years. each eon can be divided into eras, with the phanerozoic eon that began 539 million years ago being subdivided into paleozoic, mesozoic, and cenozoic eras. these three eras together comprise eleven periods ( cambrian, ordovician, silurian, devonian, carboniferous, permian, triassic, jurassic, cretaceous, tertiary, and quaternary ). the similarities among all known present - day species indicate that they have diverged through the process of evolution from their common ancestor. biologists regard the ubiquity of the genetic code as evidence of universal common descent for all bacteria, archaea, and eukaryotes. microbial mats of coexisting bacteria and archaea were the dominant form of life in the early archean eon and many of the major steps in early evolution are thought to have taken place in this environment. the earliest evidence of eukaryotes dates from 1. 85 billion years ago, and while they may have been present earlier, their diversification accelerated when they started using oxygen in their metabolism. later, around 1. 7 billion years ago, multicellular organisms began to appear, with differentiated cells performing specialised functions. algae - like multicellular land plants are dated back to about 1 billion years ago, although evidence suggests that microorganisms formed the earliest terrestrial ecosystems, at least 2. 7 billion years ago. microorganisms are thought to have paved the way for the inception of land plants in the ordovician period. land plants were so successful that they are thought to have contributed to the late devonian extinction event. ediacara biota appear during the ediacaran period, while vertebrates, along with most other modern phyla originated about 525 million years ago during the cambrian explosion. during the permian period, synapsids, including the ancestors of mammals, dominated the land, but most of this group became
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https://en.wikipedia.org/wiki/Biology
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the synchronization of coherent states of light has long been an important subject of basic research and technology. recently, a new concept for analog computers has emerged where this synchronization process can be exploited to solve computationally hard problems - potentially faster and more energy - efficient than what can be achieved with conventional computer technology today. the unit cell of such systems consists of two coherent centers that are coupled to one another in a controlled manner. here, we experimentally characterize and analyze the synchronization process of two photon bose - einstein condensates, which are coupled to one another, either dispersively or dissipatively. we show that both types of coupling are robust against a detuning of the condensate frequencies and show similar time constants in establishing mutual coherence. significant differences between these couplings arise in the behaviour of the condensate populations under imbalanced optical pumping. the combination of these two types of coupling extends the class of physical models that can be investigated using analog simulations.
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arxiv:2110.01898
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this paper presents two single channel speech dereverberation methods to enhance the quality of speech signals that have been recorded in an enclosed space. for both methods, the room acoustics are modeled using a nonnegative approximation of the convolutive transfer function ( nctf ), and to additionally exploit the spectral properties of the speech signal, such as the low rank nature of the speech spectrogram, the speech spectrogram is modeled using nonnegative matrix factorization ( nmf ). two methods are described to combine the nctf and nmf models. in the first method, referred to as the integrated method, a cost function is constructed by directly integrating the speech nmf model into the nctf model, while in the second method, referred to as the weighted method, the nctf and nmf based cost functions are weighted and summed. efficient update rules are derived to solve both optimization problems. in addition, an extension of the integrated method is presented, which exploits the temporal dependencies of the speech signal. several experiments are performed on reverberant speech signals with and without background noise, where the integrated method yields a considerably higher speech quality than the baseline nctf method and a state of the art spectral enhancement method. moreover, the experimental results indicate that the weighted method can even lead to a better performance in terms of instrumental quality measures, but that the optimal weighting parameter depends on the room acoustics and the utilized nmf model. modeling the temporal dependencies in the integrated method was found to be useful only for highly reverberant conditions.
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arxiv:1709.05557
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electronic health records ( ehrs ) offer great promises for advancing precision medicine and, at the same time, present significant analytical challenges. particularly, it is often the case that patient - level data in ehrs cannot be shared across institutions ( data sources ) due to government regulations and / or institutional policies. as a result, there are growing interests about distributed learning over multiple ehrs databases without sharing patient - level data. to tackle such challenges, we propose a novel communication efficient method that aggregates the local optimal estimates, by turning the problem into a missing data problem. in addition, we propose incorporating posterior samples of remote sites, which can provide partial information on the missing quantities and improve efficiency of parameter estimates while having the differential privacy property and thus reducing the risk of information leaking. the proposed approach, without sharing the raw patient level data, allows for proper statistical inference and can accommodate sparse regressions. we provide theoretical investigation for the asymptotic properties of the proposed method for statistical inference as well as differential privacy, and evaluate its performance in simulations and real data analyses in comparison with several recently developed methods.
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arxiv:2207.00306
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the india - based neutrino observatory ( ino ) is a project aimed at building a large underground laboratory to explore the earth ' s mater effects on the atmospheric neutrinos in multi - gev range. ino will host a 50 kton magnetized iron calorimeter detector ( ical ) in which resistive plate chambers ( rpcs ) will be the active detector elements. in ical, 28, 800 glass rpcs of 2 m $ \ times $ 2 m size will be operated in the avalanche mode. a small variation in the compositions of ionizing gaseous medium in the rpc affects its performance. study of the charge distribution of the rpc at different gas compositions is necessary to optimize the gas mixture. an rpc made with glass plates of dimension 30 cm $ \ times $ 30 cm was operated in avalanche mode with a gas mixture of $ c _ 2h _ 2f _ 4 $ / $ ic _ 4h _ { 10 } $ / $ sf _ 6 $. we have studied the performance of these rpcs at the same ambient conditions. the percentages of the $ ic _ 4h _ { 10 } $ or $ sf _ 6 $ were varied and its effect on the performance of rpc were studied. the study of the charge distribution and time resolution of the rpc signals at different gas compositions is presented in this paper.
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arxiv:1912.04954
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we present a calculation of 1 / m ^ 2 _ b corrections to the lifetime differences of b _ s mesons \ delta \ gamma _ s in the heavy - quark expansion. we find that they are small to significantly affect \ delta \ gamma _ s and present the result for lifetime difference including non - perturbative 1 / m _ b and 1 / m _ b ^ 2 corrections. we also analyze the generic \ delta b = 1 new physics contributions to \ delta \ gamma _ s and provide several examples.
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arxiv:0707.0294
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we suggest an explanation of typical incubation times statistical features based on the universal behavior of exit times for diffusion models. we give a mathematically rigorous proof of the characteristic right skewness of the incubation time distribution for very general one - dimensional diffusion models. imposing natural simple conditions on the drift coefficient, we also study these diffusion models under the assumption of noise smallness and show that the limiting exit time distributions in the limit of vanishing noise are gaussian and gumbel. thus they match the existing data as well as the other existing models do. the character of our models, however, allows us to argue that the features of the exit time distributions that we describe are universal and manifest themselves in various other situations where the times involved can be described as detection or halting times, for example, response times studied in psychology.
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arxiv:1804.05961
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understanding single pion production reactions on free nucleons is the first step towards a correct description of these processes in nuclei, which are important for signal and background contributions in current and near future accelerator neutrino oscillation experiments. in this work, we reanalyze our previous studies of neutrino - induced one - pion production on nucleons for outgoing $ \ pi n $ invariant masses below 1. 4 gev. our motivation is to get a better description of the $ \ nu _ \ mu n \ to \ mu ^ - n \ pi ^ + $ cross section, for which current theoretical models give values significantly below data. this channel is very sensitive to the crossed $ \ delta ( 1232 ) $ contribution and thus to spin 1 / 2 components in the rarita - schwinger $ \ delta $ propagator. we show how these spin 1 / 2 components are nonpropagating and give rise to contact interactions. in this context, we point out that the discrepancy with experiment might be corrected by the addition of appropriate extra contact terms and argue that this procedure will provide a natural solution to the $ \ nu _ \ mu n \ to \ mu ^ - n \ pi ^ + $ puzzle. to keep our model simple, in this work we propose to change the strength of the spin 1 / 2 components in the $ \ delta $ propagator and use the $ \ nu _ \ mu n \ to \ mu ^ - n \ pi ^ + $ data to constraint its value. with this modification, we now find a good reproduction of the $ \ nu _ \ mu n \ to \ mu ^ - n \ pi ^ + $ cross section without affecting the good results previously obtained for the other channels. we also explore how this change in the $ \ delta $ propagator affects our predictions for pion photoproduction and find also a better agreement with experiment than with the previous model.
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arxiv:1612.02343
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we report the discovery of a large hi cloud in the central regions of the virgo cluster. it is 110 x 25 kpc in size and contains 3. 4 x 10 ^ 8 msol of hi. the morphology and kinematics of this cloud strongly suggest that it consists of hi removed from the galaxy ngc 4388 by ram - pressure stripping. it is more likely the result of an interaction of the ism of ngc 4388 with the hot halo of the m86 group and not with the icm centred on m87. the large extent of the plume suggests that gas stripped from cluster galaxies can remain neutral for at least 10 ^ 8 yr. locally, the column density is well above 10 ^ 20 cm ^ - 2, suggesting that the intra - cluster hii regions known to exist in virgo may have formed from gas stripped from cluster galaxies. the existence of the hi plume suggests that stripping of infalling spirals contributes to the enrichment of the icm. the hi object in the virgo cluster recently reported by minchin et al. may have a similar origin and may therefore not be a ` ` dark galaxy ' '.
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arxiv:astro-ph/0505397
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we present theoretical model comparison with published alice results for d - mesons ( d $ ^ 0 $, d $ ^ + $ and d $ ^ { * + } $ ) in $ p $ + $ p $ collisions at $ \ sqrt { s } $ = 7 tev and $ p $ + pb collisions at $ \ sqrt { s _ { nn } } $ = 5. 02 tev. event generator hijing, transport calculation of ampt and calculations from nlo ( mnr ) and fonll have been used for this study. we found that hijing and ampt model predictions are matching with published d - meson cross - sections in $ p $ + $ p $ collisions, while both under - predict the same in $ p $ + pb collisions. attempts were made to explain the $ r _ { ppb } $ data using nlo - pqcd ( mnr ), fonll and other above mentioned models.
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arxiv:1606.07971
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we investigate the quantisation in the heisenberg representation of a relativistically covariant version of the hopfield model for dielectric media, which entails the interaction of the quantum electromagnetic field with the matter dipole fields. the matter fields are represented by a mesoscopic polarization field. a full quantisation of the model is provided in a covariant gauge, with the aim of maintaining explicit relativistic covariance. breaking of the lorentz invariance due to the intrinsic presence in the model of a preferred reference frame is also taken into account. relativistic covariance forces us to deal with the unphysical ( scalar and longitudinal ) components of the fields, furthermore it introduces, in a more tricky form, the well - known dipole ghost of standard qed in a covariant gauge. in order to correctly dispose of this contribution, we implement a generalized lautrup trick. furthermore, causality and the relation of the model with the wightman axioms are also discussed.
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arxiv:1512.08739
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the proof by ullmo and zhang of bogomolov ' s conjecture about points of small height in abelian varieties made a crucial use of an equidistribution property for ` ` small points ' ' in the associated complex abelian variety. we study the analogous equidistribution property at $ p $ - adic places. our results can be conveniently stated within the framework of the analytic spaces defined by berkovich. the first one is valid in any dimension but is restricted to ` ` algebraic metrics ' ', the second one is valid for curves, but allows for more general metrics, in particular to the normalized heights with respect to dynamical systems.
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arxiv:math/0304023
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