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social media has quickly grown into an essential tool for people to communicate and express their needs during crisis events. prior work in analyzing social media data for crisis management has focused primarily on automatically identifying actionable ( or, informative ) crisis - related messages. in this work, we show that recent advances in deep learning and natural language processing outperform prior approaches for the task of classifying informativeness and encourage the field to adopt them for their research or even deployment. we also extend these methods to two sub - tasks of informativeness and find that the deep learning methods are effective here as well. | arxiv:2007.11756 |
the klein - gordon - schroedinger system with yukawa coupling is shown to have a unique global solution for rough data, which not necessarily have finite energy. the proof uses a generalized bilinear estimate of strichartz type and bourgain ' s idea to split the data into low and high frequency parts. | arxiv:math/0203219 |
accordingly. where there is regular feedback, control theory can be used to determine how the system responds to such feedback. in practically all such systems stability is important and control theory can help ensure stability is achieved. although feedback is an important aspect of control engineering, control engineers may also work on the control of systems without feedback. this is known as open loop control. a classic example of open loop control is a washing machine that runs through a pre - determined cycle without the use of sensors. = = history = = automatic control systems were first developed over two thousand years ago. the first feedback control device on record is thought to be the ancient ktesibios ' s water clock in alexandria, egypt, around the third century bce. it kept time by regulating the water level in a vessel and, therefore, the water flow from that vessel. : 22 this certainly was a successful device as water clocks of similar design were still being made in baghdad when the mongols captured the city in 1258 ce. a variety of automatic devices have been used over the centuries to accomplish useful tasks or simply just to entertain. the latter includes the automata, popular in europe in the 17th and 18th centuries, featuring dancing figures that would repeat the same task over and over again ; these automata are examples of open - loop control. milestones among feedback, or " closed - loop " automatic control devices, include the temperature regulator of a furnace attributed to drebbel, circa 1620, and the centrifugal flyball governor used for regulating the speed of steam engines by james watt : 22 in 1788. in his 1868 paper " on governors ", james clerk maxwell was able to explain instabilities exhibited by the flyball governor using differential equations to describe the control system. this demonstrated the importance and usefulness of mathematical models and methods in understanding complex phenomena, and it signaled the beginning of mathematical control and systems theory. elements of control theory had appeared earlier but not as dramatically and convincingly as in maxwell ' s analysis. control theory made significant strides over the next century. new mathematical techniques, as well as advances in electronic and computer technologies, made it possible to control significantly more complex dynamical systems than the original flyball governor could stabilize. new mathematical techniques included developments in optimal control in the 1950s and 1960s followed by progress in stochastic, robust, adaptive, nonlinear control methods in the 1970s and 1980s. applications of control methodology have helped to make possible space travel and communication satellites, safer and more efficient aircraft, cleaner automobile engines, and cleaner and more efficient chemical processes | https://en.wikipedia.org/wiki/Control_engineering |
marginally bound systems of two types of branes are considered, such as the prototypical case of dp + 4 branes and dp branes. as the transverse separation between the two types of branes goes to zero, different behaviour occurs in the supergravity solutions depending on p ; no - hair theorems result for p < = 1 only. within the framework of the ads / cft correspondence, these supergravity no - hair results are understood as dual manifestations of the coleman - mermin - wagner theorem. furthermore, the rates of delocalization for p < = 1 are matched in a scaling analysis. talk given at ` ` strings ' 99 ' ' ; based on hep - th / 9903213 with d. marolf. | arxiv:hep-th/9910098 |
general physics of very high energy hadronic interactions is discussed. special attention is payed to the contribution of semihard processes to the interaction dynamics and to the role of parton shadowing and parton density saturation. in particular, the implementation of non - linear interaction effects in the qgsjet - ii model is discussed in detail. the predictions of the model are compared to selected accelerator data, including ones of the rhic collider, and the relation to the calculated extensive air shower characteristics is discussed. finally, the potential of accelerator and cosmic ray experiments for constraining model predictions is analyzed. | arxiv:hep-ph/0612068 |
let $ x $ be a smooth irreducible projective curve of genus $ g \ geq 2 $ over a finite field $ \ f _ { q } $ of characteristic $ p $ with $ q $ elements such that the function field $ \ f _ { q } ( x ) $ is a geometric galois extension of the rational function field of degree $ n. $ consider $ gcd ( n, d ) = 1 $, let $ m _ { l } ( n, d ) $ be the moduli space of rank $ n $ stable vector bundles over $ x $ with fixed determinant isomorphic to a $ \ mathbb f _ q $ - rational line bundle $ l $. suppose $ n _ q ( m _ l ( n, d ) ) $ denotes the cardinality of the set of $ \ f _ { q } $ - rational points of $ m _ { l } ( n, d ) $. we give an asymptotic bound of $ \ log ( n _ { q } ( m _ { l } ( n, d ) ) - ( n ^ 2 - 1 ) ( g - 1 ) \ log { q } ) $ for large genus $ g, $ depending on $ n $. further, considering this logarithmic difference as a random variable, we prove a central limit theorem over a large family of hyperelliptic curves with uniform probability measure. further, over the same family of hyperelliptic curves, we study the distribution of $ \ f _ { q } $ - rational points over the moduli space of rank $ 2 $ stable vector bundles with trivial determinant $ m ^ { s } _ { \ mathcal { o } _ { h } } ( 2, 0 ) $ and it ' s seshadri desingularisation $ { \ widetilde { n } } $ by choosing an appropriate random variable in each case. we also see that the corresponding random variables having standard gaussian distribution as $ g $ and $ q $ tends to infinity. | arxiv:2309.15085 |
w states are a valuable resource for various quantum information tasks, and several protocols to generate them have been proposed and implemented. we introduce a quantum repeater protocol to efficiently distribute three - qubit w states over arbitrary distances in a 2d triangular quantum network with polylogarithmic overhead, thereby enabling these applications between remote parties. the repeater protocol combines two ingredients that we establish : probabilistic entanglement swapping with three copies of three - qubit w states to a single long - distance three - qubit w state, and an improved entanglement purification protocol. the latter not only shows a better performance, but also an enlarged purification regime as compared to previous approaches. we show that the repeater protocol allows one to deal with errors resulting from imperfect channels or state preparation, and noisy operations, and we analyze error thresholds, achievable fidelities and overheads. | arxiv:2304.06757 |
learning with noisy labels, which aims to reduce expensive labors on accurate annotations, has become imperative in the big data era. previous noise transition based method has achieved promising results and presented a theoretical guarantee on performance in the case of class - conditional noise. however, this type of approaches critically depend on an accurate pre - estimation of the noise transition, which is usually impractical. subsequent improvement adapts the pre - estimation along with the training progress via a softmax layer. however, the parameters in the softmax layer are highly tweaked for the fragile performance due to the ill - posed stochastic approximation. to address these issues, we propose a latent class - conditional noise model ( lccn ) that naturally embeds the noise transition under a bayesian framework. by projecting the noise transition into a dirichlet - distributed space, the learning is constrained on a simplex based on the whole dataset, instead of some ad - hoc parametric space. we then deduce a dynamic label regression method for lccn to iteratively infer the latent labels, to stochastically train the classifier and to model the noise. our approach safeguards the bounded update of the noise transition, which avoids previous arbitrarily tuning via a batch of samples. we further generalize lccn for open - set noisy labels and the semi - supervised setting. we perform extensive experiments with the controllable noise data sets, cifar - 10 and cifar - 100, and the agnostic noise data sets, clothing1m and webvision17. the experimental results have demonstrated that the proposed model outperforms several state - of - the - art methods. | arxiv:1903.02152 |
computational fluid dynamics ( cfd ) solvers employing two - equation eddy viscosity models are the industry standard for simulating turbulent flows using the reynolds - averaged navier - stokes ( rans ) formulation. while these methods are computationally less expensive than direct numerical simulations, they can still incur significant computational costs to achieve the desired accuracy. in this context, physics - informed neural networks ( pinns ) offer a promising approach for developing parametric surrogate models that leverage both existing, but limited cfd solutions and the governing differential equations to predict simulation outcomes in a computationally efficient, differentiable, and near real - time manner. in this work, we build upon the previously proposed rans - pinn framework, which only focused on predicting flow over a cylinder. to investigate the efficacy of rans - pinn as a viable approach to building parametric surrogate models, we investigate its accuracy in predicting relevant turbulent flow variables for both internal and external flows. to ensure training convergence with a more complex loss function, we adopt a novel sampling approach that exploits the domain geometry to ensure a proper balance among the contributions from various regions within the solution domain. the effectiveness of this framework is then demonstrated for two scenarios that represent a broad class of internal and external flow problems. | arxiv:2410.18917 |
we present an opto - electrical cooling scheme for polar molecules based on a sisyphus - type cooling cycle in suitably tailored electric trapping fields. dissipation is provided by spontaneous vibrational decay in a closed level scheme found in symmetric - top rotors comprising six low - field - seeking rovibrational states. a generic trap design is presented. suitable molecules are identified with vibrational decay rates on the order of 100hz. a simulation of the cooling process shows that the molecular temperature can be reduced from 1k to 1mk in approximately 10s. the molecules remain electrically trapped during this time, indicating that the ultracold regime can be reached in an experimentally feasible scheme. | arxiv:0904.4144 |
computer systems are facing biggest threat in the form of malicious data which causing denial of service, information theft, financial and credibility loss etc. no defense technique has been proved successful in handling these threats. intrusion detection and prevention systems ( idpss ) being best of available solutions. these techniques are getting more and more attention. although intrusion prevention systems ( ipss ) show a good level of success in detecting and preventing intrusion attempts to networks, they show a visible deficiency in their performance when they are employed on fast networks. in this paper we have presented a design including quantitative and qualitative methods to identify improvement areas in ipss. focus group is used for qualitative analysis and experiment is used for quantitative analysis. this paper also describes how to reduce the responding time for ips when an intrusion occurs on network, and how can ips be made to perform its tasks successfully without effecting network speed negatively. | arxiv:1006.4546 |
a definition of k41 scaling law for suitable families of measures is given and investigated. first, a number of necessary conditions are proved. they imply the absence of scaling laws for 2d stochastic navier - stokes equations and for the stochastic stokes ( linear ) problem in any dimension, while they imply a lower bound on the mean vortex stretching in 3d. second, for 3d stochastic navier - stokes equations necessary and sufficient conditions for k41 are proved, translating the problem into bounds for energy and enstrophy of high and low modes respectively. the validity of such conditions in 3d remains open. finally, a stochastic vortex model with such properties is presented. | arxiv:math-ph/0507044 |
the construction of the first baryon operators for staggered lattice qcd exploited the taste symmetry to emulate physical quark flavor ; contemporary 2 + 1 flavor simulations explicitly include three physical quark flavors and necessitate interpreting a valence sector with twelve quarks. after discussing expected features of the resulting baryon spectrum, i consider the spectra of operators transforming irreducibly under su ( 3 ) xgts, the direct product of flavor su ( 3 ) and the geometrical time - slice group of the 1 - flavor staggered theory. i then describe the construction of a set of maximally local baryon operators transforming irreducibly under su ( 3 ) xgts and enumerate this set. in principle, the operators listed here could be used to extract the masses of all the lightest spin - 1 / 2 and spin - 3 / 2 baryon resonances of staggered qcd. using appropriate operators from this set in partially quenched simulations should allow for particularly clean 2 + 1 flavor calculations of the masses of the nucleon and the lightest decuplet. | arxiv:hep-lat/0611023 |
we analyze random walk in the upper half of a three dimensional lattice which goes down whenever it encounters a new vertex, a. k. a. excited random walk. we show that it is recurrent with an expected number of returns of square - root log n. | arxiv:math/0509464 |
audio data augmentation is a key step in training deep neural networks for solving audio classification tasks. in this paper, we introduce audiogmenter, a novel audio data augmentation library in matlab. we provide 15 different augmentation algorithms for raw audio data and 8 for spectrograms. we efficiently implemented several augmentation techniques whose usefulness has been extensively proved in the literature. to the best of our knowledge, this is the largest matlab audio data augmentation library freely available. we validate the efficiency of our algorithms evaluating them on the esc - 50 dataset. the toolbox and its documentation can be downloaded at https : / / github. com / lorisnanni / audiogmenter. | arxiv:1912.05472 |
vector - meson - dominance model contribution to $ \ pi ^ 0 \ to 4 \ gamma $ is calculated. the result confirms old estimates that this contribution is much smaller than the purely electromagnetic photon spliting graph contribution calculated earlier. | arxiv:hep-ph/0311089 |
we study pairwise quantum entanglement in systems of fermions itinerant in a lattice from a second - quantized perspective. entanglement in the grand - canonical ensemble is studied, both for energy eigenstates and for the thermal state. relations between entanglement and superconducting correlations are discussed in a bcs - like model and for $ \ eta $ - pair superconductivity. | arxiv:quant-ph/0201028 |
here we report a working physical model of a programmable neural nanonetwork based on a nanostructured conductive polymer - polyaniline. the device can be programmed owing to controlled growth of nanowires, a method developed in our laboratory. the response ( output signal ) of the network depends on the activated input line, but also on the amplitude of the input signals. the system is able to analyze multiple input signals in parallel and in real time. this is still considered as a challenge. | arxiv:2412.09999 |
mkm has been defined as the quest for technologies to manage mathematical knowledge. mkm " in the small " is well - studied, so the real problem is to scale up to large, highly interconnected corpora : " mkm in the large ". we contend that advances in two areas are needed to reach this goal. we need representation languages that support incremental processing of all primitive mkm operations, and we need software architectures and implementations that implement these operations scalably on large knowledge bases. we present instances of both in this paper : the mmt framework for modular theory - graphs that integrates meta - logical foundations, which forms the base of the next omdoc version ; and tntbase, a versioned storage system for xml - based document formats. tntbase becomes an mmt database by instantiating it with special mkm operations for mmt. | arxiv:1005.5232 |
the near - side ridge observed in a + a collisions at rhic has been described as arising from the radial flow of glasma flux tubes formed at very early times in the collisions. we investigate the viability of this scenario by performing a non - perturbative numerical computation of double inclusive gluon production in the glasma. our results support the conjecture that the range of transverse color screening of correlations determining the size of the flux tubes is a semi - hard scale, albeit with non - trivial structure. we discuss our results in the context of ridge correlations in the rhic heavy ion experiments. | arxiv:0911.2068 |
we statistically study the physical properties of a sample of narrow absorption line ( nal ) systems looking for empirical evidences to distinguish between intrinsic and intervening nals without taking into account any a priori definition or velocity cut - off. we analyze the spectra of 100 quasars with 3. 5 < z $ \ rm _ { em } $ < 4. 5, observed with x - shooter / vlt in the context of the xq - 100 legacy survey. we detect a $ \ sim $ 8 $ \ sigma $ excess in the number density of absorbers within 10, 000 km / s of the quasar emission redshift with respect to the random occurrence of nals. this excess does not show a dependence on the quasar bolometric luminosity and it is not due to the redshift evolution of nals. it extends far beyond the standard 5000 km / s cut - off traditionally defined for associated absorption lines. we propose to modify this definition, extending the threshold to 10, 000 km / s when also weak absorbers ( equivalent width < 0. 2 \ aa ) are considered. we infer nv is the ion that better traces the effects of the quasar ionization field, offering the best statistical tool to identify intrinsic systems. following this criterion we estimate that the fraction of quasars in our sample hosting an intrinsic nal system is 33 percent. lastly, we compare the properties of the material along the quasar line of sight, derived from our sample, with results based on close quasar pairs investigating the transverse direction. we find a deficiency of cool gas ( traced by cii ) along the line of sight associated with the quasar host galaxy, in contrast with what is observed in the transverse direction. | arxiv:1605.04607 |
the general integrability cases in the rigid - body dynamics are the solutions of lagrange, euler, kovalevskaya, and goryachev - chaplygin. the first two can be included in smale ' s scheme for studying the phase topology of natural systems with symmetries. we modify smale ' s program to suit the most complicated last two cases with non - linear first integrals. the bifurcation sets are found and all transformations of the integral tori are described and classified. new non - trivial bifurcation of a torus is established in the kovalevskaya and goraychev - chaplygin cases. | arxiv:0906.2548 |
the internet of things ( iot ), which is the network of physical devices embedded with sensors, actuators, and connec - tivity, is being accelerated into the mainstream by the emergence of 5g wireless networking. this paper presents an uncoordinated non - orthogonal random access protocol, an enhancement to the recently introduced aloha - noma protocol, which provides high throughput, while being matched to the low complexity requirements and the sporadic traffic pattern of iot devices. under ideal conditions it has been shown that aloha - noma, using power - domain orthogonality, can significantly increase the throughput using sic ( successive interference cancellation ) to enable correct reception of multiple simultaneous transmitted signals. for this ideal performance, the enhanced aloha - noma receiver adaptively learns the number of active devices ( which is not known a priori ) using a form of multi - hypothesis testing. for small numbers of simultaneous transmissions, it is shown that there can be substantial throughput gain of 6. 9 db relative to pure aloha for 0. 25 probability of transmission and up to 3 active transmitters. | arxiv:1803.09513 |
we investigate the bias - modulated dynamics of a strongly driven two - level system using the counter - rotating - hybridized rotating - wave ( chrw ) method. this chrw method treats the driving field and the bias on equal footing by a unitary transformation with two parameters $ \ xi $ and $ \ zeta $, and is nonperturbative in driving strength, tunneling amplitude or bias. in addition, this chrw method is beyond the traditional rotating - wave approximation ( rabi - rwa ) and yet by properly choosing the two parameters $ \ xi $ and $ \ zeta $, the transformed hamiltonian takes the rwa form with a renormalized energy splitting and a renormalized driving strength. the reformulated chrw method possesses the same mathematical simplicity as the rabi - rwa approach and thus allows us to calculate analytically the dynamics and explore explicitly the effect of the bias. we show that the chrw method gives the accurate driven dynamics for a wide range of parameters as compared to the numerically exact results. when energy scales of the driving are comparable to the intrinsic energy scale of the two - level systems, the counter - rotating interactions and static bias profoundly influence the generalized rabi frequency. in this regime, where ordinary perturbation approaches fail, the chrw works very well and efficiently. we also demonstrate the dynamics of the system in the strong - driving and off - resonance cases for which the rabi - rwa method breaks down but the chrw method remains valid. we obtain analytical expressions for the generalized rabi frequency and bias - modulated bloch - siegert shift as functions of the bias, tunneling and driving field parameters. the chrw approach is a mathematically simple and physically clear method. it can be applied to treat some complicated problems for which a numerical study is difficult to perform. | arxiv:1602.04413 |
this paper demonstrates the integration model - based design approaches or vehicle control, with validation in a freely available open - source simulator. continued interest in autonomous vehicles and their deployment is driven by the potential benefits of their use. however, it can be challenging to transition new theoretical approaches into unknown simulation environments. thus, it is critical for experts from other fields, whose insights may be necessary to continue to advance autonomy, to be able to create control applications with the potential to transition to practice. in this article, we will explain how to use the cat vehicle simulator and ros packages to create and test vehicle controllers. the methodology of developing the control system in this article takes the approach of model - based design using simulink, and the ros toolbox, followed by code generation to create a standalone c + + ros node. such ros nodes can be integrated through roslaunch in the cat vehicle ros package. | arxiv:2301.04574 |
the optical turbulence above dome c in winter is mainly concentrated in the first tens of meters above the ground. properties of this so - called surface layer ( sl ) were investigated during the period 2007 - 2012 by a set of sonics anemometers placed on a 45 m high tower. we present the results of this long - term monitoring of the refractive index structure constant cn2 within the sl, and confirm its thickness of 35m. we give statistics of the contribution of the sl to the seeing and coherence time. we also investigate properties of large scale structure functions of the temperature and show evidence of a second inertial zone at kilometric spatial scales. | arxiv:1811.07585 |
we prove a matrix trace inequality for completely monotone functions and for bernstein functions. as special cases we obtain non - trivial trace inequalities for the power function x - > x ^ q, which for certain values of q complement mccarthy ' s trace inequality and for others strenghten it. | arxiv:1109.3057 |
we propose that certain white dwarf ( wd ) planets, such as wd 1856 + 534 b, may form out of material from a stellar companion that tidally disrupts from common envelope evolution with the wd progenitor star. the disrupted companion shreds into an accretion disc, out of which a gas giant protoplanet forms due to gravitational instability. to explore this scenario, we make use of detailed stellar evolution models consistent with wd 1856 + 534. the minimum mass companion that produces a gravitationally - unstable disc after tidal disruption is $ \ sim0. 15 \, \ mathrm { m } _ \ odot $. in this scenario, wd 1856 + 534 b might have formed at or close to its present separation, in contrast to other proposed scenarios where it would have migrated in from a much larger separation. planet formation from tidal disruption is a new channel for producing second - generation planets around wds. | arxiv:2407.14190 |
the high - cadence, comprehensive view of the solar corona by sdo / aia shows many events that are widely separated in space while occurring close together in time. in some cases, sets of coronal events are evidently causally related, while in many other instances indirect evidence can be found. we present case studies to highlight a variety of coupling processes involved in coronal events. we find that physical linkages between events do occur, but concur with earlier studies that these couplings appear to be crucial to understanding the initiation of major eruptive or explosive phenomena relatively infrequently. we note that the post - eruption reconfiguration time scale of the large - scale corona, estimated from the euv afterglow, is on average longer than the mean time between cmes, so that many cmes originate from a corona that is still adjusting from a previous event. we argue that the coronal field is intrinsically global : current systems build up over days to months, the relaxation after eruptions continues over many hours, and evolving connections easily span much of a hemisphere. this needs to be reflected in our modeling of the connections from the solar surface into the heliosphere to properly model the solar wind, its perturbations, and the generation and propagation of solar energetic particles. however, the large - scale field cannot be constructed reliably by currently available observational resources. we assess the potential of high - quality observations from beyond earth ' s perspective and advanced global modeling to understand the couplings between coronal events in the context of cmes and solar energetic particle events. | arxiv:1305.0801 |
we study the distribution of optimal path lengths in random graphs with random weights associated with each link ( ` ` disorder ' ' ). with each link $ i $ we associate a weight $ \ tau _ i = \ exp ( ar _ i ) $ where $ r _ i $ is a random number taken from a uniform distribution between 0 and 1, and the parameter $ a $ controls the strength of the disorder. we suggest, in analogy with the average length of the optimal path, that the distribution of optimal path lengths has a universal form which is controlled by the expression $ \ frac { 1 } { p _ c } \ frac { \ ell _ { \ infty } } { a } $, where $ \ ell _ { \ infty } $ is the optimal path length in strong disorder ( $ a \ to \ infty $ ) and $ p _ c $ is the percolation threshold. this relation is supported by numerical simulations for erd \ h { o } s - r \ ' enyi and scale - free graphs. we explain this phenomenon by showing explicitly the transition between strong disorder and weak disorder at different length scales in a single network. | arxiv:cond-mat/0508039 |
##bniz did ) " combine many differing ideas under the two unifying themes of the derivative and the integral, show the connection between the two, and turn calculus into the great problem - solving tool we have today ". the intellectual careers of both newton and leibniz are well - documented and there is no indication of their work not being their own ; however, it is not known with certainty whether the immediate predecessors of newton and leibniz, " including, in particular, fermat and roberval, [ may have ] learned of some of the ideas of the islamic and indian mathematicians through sources we are not now aware. " this is an area of current research, especially in the manuscript collections of spain and maghreb, and is being pursued, among other places, at the cnrs. = = see also = = = = notes = = = = references = = bourbaki, nicolas ( 1998 ), elements of the history of mathematics, berlin, heidelberg, and new york : springer - verlag, 301 pages, isbn 978 - 3 - 540 - 64767 - 6. boyer, c. b. ; merzback ( fwd. by isaac asimov ), u. c. ( 1991 ), history of mathematics, new york : john wiley and sons, 736 pages, isbn 978 - 0 - 471 - 54397 - 8. bressoud, david ( 2002 ), " was calculus invented in india? ", the college mathematics journal, 33 ( 1 ) : 2 – 13, doi : 10. 2307 / 1558972, jstor 1558972. bronkhorst, johannes ( 2001 ), " panini and euclid : reflections on indian geometry ", journal of indian philosophy, 29 ( 1 – 2 ), springer netherlands : 43 – 80, doi : 10. 1023 / a : 1017506118885, s2cid 115779583. burnett, charles ( 2006 ), " the semantics of indian numerals in arabic, greek and latin ", journal of indian philosophy, 34 ( 1 – 2 ), springer - netherlands : 15 – 30, doi : 10. 1007 / s10781 - 005 - 8153 - z, s2cid 170783929. burton, david m. ( 1997 ), the history of mathematics : an introduction, the mcgraw - hill companies, inc., pp. 193 – 220. | https://en.wikipedia.org/wiki/Indian_mathematics |
we update the uncertainty analysis on $ s $ parameter of the electroweak chiral lagrangian ( ewcl ) by including the lep - ii w pair production data. we find that experimental data still allow a positive $ s ^ { exp } ( 1 \ textrm { tev } ) $. | arxiv:hep-ph/0703189 |
the temperature dependence of coulomb blockade peak height correlation is used to investigate how adding electrons to a quantum dot alters or " scrambles " its electronic spectrum. deviations from finite - temperature random matrix theory with an unchanging spectrum indicate spectral scrambling after a small number of electrons are added. enhanced peak - to - peak correlations at low temperature are observed. peak height statistics show similar behavior in several dot configurations despite significant differences in correlations. | arxiv:cond-mat/9808166 |
the observational detection of some metastable isomers in the interstellar medium with abundances comparable to those of the most stable isomer, or even when the stable isomer is not detected, highlights the importance of non - equilibrium chemistry. this challenges our understanding of the interstellar chemistry. we present a chemical study of isomers through the sulphur isomer pair hncs and hscn, since hscn has been observed in regions where its stable isomer has not been detected, and the observed hncs / hscn ratio seems to significantly vary from cold to warm regions. we have used the nautilus chemical code to model the formation and destruction paths of hncs and hscn in different astrochemical scenarios, and the time evolution of the hncs / hscn ratio. we have also analysed the influence of the environmental conditions on their chemical abundances. we present an observational detection of the metastable isomer hscn in the class i object b1 - a, but not of the stable isomer hncs, despite hncs lying 3200 k lower in energy than hscn. our results show an hncs / hscn ratio sensitive to the gas temperature and the evolutionary time, with the highest values obtained at early stages ( t < 10 ^ 4 yr ) and low ( tg < 20 k ) temperatures. the results suggest a different efficiency of the isomerisation processes depending on the source temperature. the progressive decrease of hncs / hscn with gas temperature at early evolutionary times indicates that this ratio may be used as a tracer of cold young objects. this work also demonstrates the key role of grain surface chemistry in the formation of the isomer pair hncs and hscn in cold regions, and the importance of the ions h2ncs + and hncsh + in warm / hot regions. since most of the interstellar regions where hscn is detected are cold regions, a larger sample including sources characterised by high temperatures are needed to corroborate the theoretical results. | arxiv:2411.05517 |
according to the bulk - edge correspondence principle, the physics of the gapless edge in the quantum hall effect determines topological order in the gapped bulk. as the bulk is less accessible, the last two decades saw the emergence of several experimental techniques that invoke the study of the compressible edge. we review the properties of the edge, and describe several experimental techniques that include shot noise and thermal noise measurements, interferometry, and energy ( thermal ) transport at the edge. we pay special attention to the filling factor 5 / 2 in the first excited landau level ( in two - dimensional electron gas in gaas ), where experimental evidence of a non - abelian topological order was found. a brief discussion is devoted to recent interferometry experiments that uncovered unexpected physics in the integer quantum hall effect. the chapter also addresses the theory of edge states, for systems with abelian and non - abelian topological orders. | arxiv:1910.07046 |
although shannon mutual information has been widely used, its effective calculation is often difficult for many practical problems, including those in neural population coding. asymptotic formulas based on fisher information sometimes provide accurate approximations to the mutual information but this approach is restricted to continuous variables because the calculation of fisher information requires derivatives with respect to the encoded variables. in this paper, we consider information - theoretic bounds and approximations of the mutual information based on kullback - - leibler divergence and r \ ' { e } nyi divergence. we propose several information metrics to approximate shannon mutual information in the context of neural population coding. while our asymptotic formulas all work for discrete variables, one of them has consistent performance and high accuracy regardless of whether the encoded variables are discrete or continuous. we performed numerical simulations and confirmed that our approximation formulas were highly accurate for approximating the mutual information between the stimuli and the responses of a large neural population. these approximation formulas may potentially bring convenience to the applications of information theory to many practical and theoretical problems. | arxiv:1903.01500 |
the inhomogeneous incompressible navier - stokes equations with fractional laplacian dissipations in the multi - dimensional whole space are considered. the existence and uniqueness of global strong solution with vacuum are established for large initial data. the exponential decay - in - time of the strong solution is also obtained, which is different from the homogeneous case. the initial density may have vacuum and even compact support. | arxiv:1806.04464 |
let k be a complete discrete valuation field of mixed characteristic ( 0, p ) with perfect residue field. let ( \ pi _ n ) _ { n \ ge 0 } be a system of p - power roots of a uniformizer \ pi = \ pi _ 0 of k with \ pi ^ p _ { n + 1 } = \ pi _ n, and define g _ s ( resp. \ g _ { \ infty } ) the absolute galois group of k ( \ pi _ s ) ( resp. \ k _ { \ infty } : = \ bigcup _ { n \ ge 0 } k ( \ pi _ n ) ). in this paper, we study g _ s - equivatiantness properties of g _ { \ infty } - equivariant homomorphisms between torsion ( potentially ) crystalline representations | arxiv:1304.2095 |
a total weighting of the vertices and edges of a hypergraph is called vertex - coloring if the total weights of the vertices yield a proper coloring of the graph, i. e., every edge contains at least two vertices with different weighted degrees. in this note we show that such a weighting is possible if every vertex has two, and every edge has three weights to choose from, extending a recent result on graphs to hypergraphs. | arxiv:1312.6329 |
we study model - based offline reinforcement learning with general function approximation without a full coverage assumption on the offline data distribution. we present an algorithm named constrained pessimistic policy optimization ( cppo ) which leverages a general function class and uses a constraint over the model class to encode pessimism. under the assumption that the ground truth model belongs to our function class ( i. e., realizability in the function class ), cppo has a pac guarantee with offline data only providing partial coverage, i. e., it can learn a policy that competes against any policy that is covered by the offline data. we then demonstrate that this algorithmic framework can be applied to many specialized markov decision processes where additional structural assumptions can further refine the concept of partial coverage. two notable examples are : ( 1 ) low - rank mdp with representation learning where the partial coverage condition is defined using a relative condition number measured by the unknown ground truth feature representation ; ( 2 ) factored mdp where the partial coverage condition is defined using density ratio based concentrability coefficients associated with individual factors. | arxiv:2107.06226 |
billions of usd are invested in new artists and songs by the music industry every year. this research provides a new strategy for assessing the hit potential of songs, which can help record companies support their investment decisions. a number of models were developed that use both audio data, and a novel feature based on social media listening behaviour. the results show that models based on early adopter behaviour perform well when predicting top 20 dance hits. | arxiv:2010.09489 |
contrary to recent experimental evidence suggesting that the monocyclic ring is the most stable 20 - atom carbon species, highly accurate calculations convincingly predict that the smallest fullerene, the dodecahedron c $ _ { 20 } $, has the lowest energy. a related corannulene - like bowl is nearly degenerate in energy to the fullerene. thermodynamic considerations suggest that at formation temperatures of around 700 k the bowl should be the dominant species. the recent application of gradient corrections to lda which supported the ring structure is qualitatively in error. ( rk - 94 - 02 ) | arxiv:chem-ph/9409001 |
this paper proposes consensus - before - talk ( cbt ), a spectrum etiquette architecture leveraged by distributed ledger technology ( dlt ). in cbt, secondary users ' spectrum access requests reach a consensus in a distributed way, thereby enabling collision - free distributed dynamic spectrum access. to achieve this consensus, the secondary users need to pay for the extra request exchanging delays. incorporating the consensus delay, the end - to - end latency under cbt is investigated. both the latency analysis and numerical evaluation validate that the proposed cbt achieves the lower end - to - end latency particularly under severe secondary user traffic, compared to the listen - before - talk ( lbt ) benchmark scheme. | arxiv:1808.08356 |
we present the quantum and classical mechanics formalisms for a particle with position - dependent mass in the context of a deformed algebraic structure ( named $ \ kappa $ - algebra ), motivated by the kappa - statistics. from this structure we obtain deformed versions of the position and momentum operators, which allow to define a point canonical transformation that maps a particle with constant mass in a deformed space into a particle with position - dependent mass in the standard space. we illustrate the formalism with a particle confined in an infinite potential well and the mathews - lakshmanan oscillator, exhibiting uncertainty relations depending on the deformation. | arxiv:2007.11184 |
open set recognition ( osr ) requires models to classify known samples while detecting unknown samples for real - world applications. existing studies show impressive progress using unknown samples from auxiliary datasets to regularize osr models, but they have proved to be sensitive to selecting such known outliers. in this paper, we discuss the aforementioned problem from a new perspective : can we regularize osr models without elaborately selecting auxiliary known outliers? we first empirically and theoretically explore the role of foregrounds and backgrounds in open set recognition and disclose that : 1 ) backgrounds that correlate with foregrounds would mislead the model and cause failures when encounters ' partially ' known images ; 2 ) backgrounds unrelated to foregrounds can serve as auxiliary known outliers and provide regularization via global average pooling. based on the above insights, we propose a new method, background mix ( backmix ), that mixes the foreground of an image with different backgrounds to remove the underlying fore - background priors. specifically, backmix first estimates the foreground with class activation maps ( cams ), then randomly replaces image patches with backgrounds from other images to obtain mixed images for training. with backgrounds de - correlated from foregrounds, the open set recognition performance is significantly improved. the proposed method is quite simple to implement, requires no extra operation for inferences, and can be seamlessly integrated into almost all of the existing frameworks. the code is released on https : / / github. com / vanixxz / backmix. | arxiv:2503.17717 |
some factors connecting the evolutionary histories of galaxies with the characteristics of their cluster systems are reviewed. unanswered questions include : how is one to understand the observation that some globular cluster systems have disk kinematics whereas others do not? why do some galaxies have cluster systems with unimodal metallicity distributions, whereas others have bimodal metallicity distributions? what caused the average ellipticity of individual clusters to differ from galaxy to galaxy? | arxiv:astro-ph/0308194 |
let $ g $ be a connected bridgeless $ ( n, m ) $ - graph which may have loops and multiedges, and let $ f ( g, t ) $ denote the flow polynomial of $ g $. dong and koh \ cite { dong1 } established an upper bound for the absolute value of coefficient $ c _ { i } $ of $ t ^ { i } $ in the expansion of $ f ( g, t ) $, where $ 0 \ leqslant i \ leqslant m - n + 1 $. in this paper, we refine the aforementioned bound. specifically, we demonstrate that when $ n \ leqslant m \ leqslant n + 3 $, $ | c _ { i } | \ leqslant d _ { i } $, where $ d _ { i } $ is the coefficient of $ t ^ { i } $ in the expansion $ \ prod \ limits _ { j = 1 } ^ { m - n + 1 } ( t + j ) $ ; and when $ m \ geqslant n + 4 $, $ | c _ { i } | \ leqslant d _ { i } $, with $ d _ { i } $ being the coefficient of $ t ^ { i } $ in the expansion $ ( t + 1 ) ( t + 2 ) ( t + 3 ) ^ { 2 } ( t + 4 ) ^ { m - n - 3 } $. furthermore, we prove that if $ g $ is a connected bridgeless cubic graph having only real flow roots, then $ b _ { i } \ leqslant | c _ { i } | $, where $ b _ { i } $ is the coefficient of $ t ^ { i } $ in the expansion $ ( t + 1 ) ( t + 2 ) ^ { \ frac { n } { 2 } } $. notably, if $ g $ is simple connected bridgeless cubic graph with only real flow roots, then $ b _ { i } $ is the coefficient of $ t ^ { i } $ in the expansion $ ( t + 1 ) ( t + 2 ) ^ { \ frac { n } { 2 } - 2 } ( t + 3 ) ^ { 2 } $. | arxiv:2502.12773 |
we consider the problems zero extension and metric labelling under the paradigm of parameterized complexity. these are natural, well - studied problems with important applications, but have previously not received much attention from parameterized complexity. depending on the chosen cost function $ \ mu $, we find that different algorithmic approaches can be applied to design fpt - algorithms : for arbitrary $ \ mu $ we parameterized by the number of edges that cross the cut ( not the cost ) and show how to solve zero extension in time $ o ( | d | ^ { o ( k ^ 2 ) } n ^ 4 \ log n ) $ using randomized contractions. we improve this running time with respect to both parameter and input size to $ o ( | d | ^ { o ( k ) } m ) $ in the case where $ \ mu $ is a metric. we further show that the problem admits a polynomial sparsifier, that is, a kernel of size $ o ( k ^ { | d | + 1 } ) $ that is independent of the metric $ \ mu $. with the stronger condition that $ \ mu $ is described by the distances of leaves in a tree, we parameterize by a gap parameter $ ( q - p ) $ between the cost of a true solution $ q $ and a ` discrete relaxation ' $ p $ and achieve a running time of $ o ( | d | ^ { q - p } | t | m + | t | \ phi ( n, m ) ) $ where $ t $ is the size of the tree over which $ \ mu $ is defined and $ \ phi ( n, m ) $ is the running time of a max - flow computation. we achieve a similar running for the more general metric labelling, while also allowing $ \ mu $ to be the distance metric between an arbitrary subset of nodes in a tree using tools from the theory of vcsps. we expect the methods used in the latter result to have further applications. | arxiv:1802.06026 |
electric - field - controlled f \ " orster resonance energy transfer ( fret ) between rydberg helium ( he ) atoms and ground - state ammonia ( nh $ _ 3 $ ) molecules has been studied at translational temperatures below 100 mk. the experiments were performed in an intrabeam collision apparatus with pulsed supersonic beams of nh $ _ 3 $ seeded in he. a range of f \ " orster resonances, between triplet rydberg states in he with principal quantum numbers of 38, 39 and 40, and the inversion intervals in nh $ _ 3 $ were investigated. resonance widths as low as $ 100 \ pm20 $ mhz were observed for rydberg - rydberg transitions with electric dipole transition moments of 3270 d. these widths result from binary collisions at a mean center - of - mass speed of $ 19. 3 \ pm2. 6 $ m / s. for transitions in which the initially prepared rydberg states were strongly polarized, with large induced static electric dipole moments, van der waals interactions between the collision partners increased the resonance widths to $ \ sim750 $ mhz. from measurements of the rate of fret for the narrowest resonances observed, a density of nh $ _ 3 $ of $ ( 9. 4 \ pm0. 3 ) \ times10 ^ { 9 } $ cm $ ^ { - 3 } $ in the upper ground - state inversion sublevel in the interaction region of the apparatus was determined non - destructively. | arxiv:2211.09880 |
a mechanism deriving new well - posed evolutionary equations from given ones is inspected. it turns out that there is one particular spatial operator from which many of the standard evolutionary problems of mathematical physics can be generated by this abstract mechanism using suitable projections. the complexity of the dynamics of the phenomena considered can be described in terms of suitable material laws. the idea is illustrated with a number of concrete examples. | arxiv:1203.6762 |
we discuss the poisson structures, lax matrices, $ r $ - matrices, bi - hamiltonian structures, the variables of separation and other attributes of the modern theory of dynamical systems in application to the integrable euler top and to the nonholonomic chaplygin ball. | arxiv:1002.1123 |
in this paper we propose and analyze a method based on the riccati transformation for solving the evolutionary hamilton - jacobi - bellman equation arising from the stochastic dynamic optimal allocation problem. we show how the fully nonlinear hamilton - jacobi - bellman equation can be transformed into a quasi - linear parabolic equation whose diffusion function is obtained as the value function of certain parametric convex optimization problem. although the diffusion function need not be sufficiently smooth, we are able to prove existence, uniqueness and derive useful bounds of classical h \ " older smooth solutions. we furthermore construct a fully implicit iterative numerical scheme based on finite volume approximation of the governing equation. a numerical solution is compared to a semi - explicit traveling wave solution by means of the convergence ratio of the method. we compute optimal strategies for a portfolio investment problem motivated by the german dax 30 index as an example of application of the method. | arxiv:1307.3672 |
we derive the schwinger - dyson / loop equations for the usp ( 2k ) matrix model which close among the closed and open wilson loop variables. these loop equations exhibit a complete set of the joining and splitting interactions required for the nonorientable type i superstrings. the open loops realize the so ( 2n _ f ) chan - paton factor and their linearized loop equations derive the mixed dirichlet / neumann boundary conditions. | arxiv:hep-th/9812177 |
we consider x 1,..., x n a sample of data on the circle s 1, whose distribution is a twocomponent mixture. denoting r and q two rotations on s 1, the density of the x i ' s is assumed to be g ( x ) = pf ( r - - 1 x ) + ( 1 - - p ) f ( q - - 1 x ), where p $ \ in $ ( 0, 1 ) and f is an unknown density on the circle. in this paper we estimate both the parametric part $ \ theta $ = ( p, r, q ) and the nonparametric part f. the specific problems of identifiability on the circle are studied. a consistent estimator of $ \ theta $ is introduced and its asymptotic normality is proved. we propose a fourier - based estimator of f with a penalized criterion to choose the resolution level. we show that our adaptive estimator is optimal from the oracle and minimax points of view when the density belongs to a sobolev ball. our method is illustrated by numerical simulations. | arxiv:2103.07318 |
the gravitational lens system mg j0414 + 0534 is formed by an elliptical galaxy at redshift ~ 0. 96 and a quasar at z ~ 2. 64. the system geometry is typical of lensing by an elliptical galaxy with the qso close to and inside a fold caustic. it shows 4 images of the background source, and a partial einstein ring is visible at optical wavelengths. it was observed with a global - vlbi array at 18 cm in june 2008. we present here the imaging results and a preliminary lens model constrained by these observations. | arxiv:1011.6652 |
the dissipated spaces form a class of compacta which contains both the scattered compacta and the compact lotses ( linearly ordered topological spaces ), and a number of theorems true for these latter two classes are true more generally for the dissipated spaces. for example, every regular borel measure on a dissipated space is separable. a product of two compact lotses is usually not dissipated, but it may satisfy a weakening of that property. in fact, the degree of dissipation of a space can be used to distinguish topologically a product of n lotses from a product of m lotses. | arxiv:math/0703429 |
. for example, ( 0, 1 ) = { x 0 < x < 1 } { \ displaystyle ( 0, 1 ) = \ { x \ mid 0 < x < 1 \ } } is the interval of all real numbers greater than 0 and less than 1. ( this interval can also be denoted by ] 0, 1 [, see below ). the open interval ( 0, + ∞ ) consists of real numbers greater than 0, i. e., positive real numbers. the open intervals have thus one of the forms ( a, b ) = { x ∈ r a < x < b }, ( − ∞, b ) = { x ∈ r x < b }, ( a, + ∞ ) = { x ∈ r a < x }, ( − ∞, + ∞ ) = r, ( a, a ) = ∅, { \ displaystyle { \ begin { aligned } ( a, b ) & = \ { x \ in \ mathbb { r } \ mid a < x < b \ }, \ \ ( - \ infty, b ) & = \ { x \ in \ mathbb { r } \ mid x < b \ }, \ \ ( a, + \ infty ) & = \ { x \ in \ mathbb { r } \ mid a < x \ }, \ \ ( - \ infty, + \ infty ) & = \ mathbb { r }, \ \ ( a, a ) & = \ emptyset, \ end { aligned } } } where a { \ displaystyle a } and b { \ displaystyle b } are real numbers such that a < b. { \ displaystyle a < b. } in the last case, the resulting interval is the empty set and does not depend on a { \ displaystyle a }. the open intervals are those intervals that are open sets for the usual topology on the real numbers. a closed interval is an interval that includes all its endpoints and is denoted with square brackets. for example, [ 0, 1 ] means greater than or equal to 0 and less than or equal to 1. closed intervals have one of the following forms in which a and b are real numbers such that a < b : { \ displaystyle a < b \ colon } [ a, b ] = { x ∈ r a ≤ x ≤ b }, ( − ∞, b ] = { x ∈ r x ≤ b } | https://en.wikipedia.org/wiki/Interval_(mathematics) |
we study semiparametric varying - coefficient partially linear models when some linear covariates are not observed, but ancillary variables are available. semiparametric profile least - square based estimation procedures are developed for parametric and nonparametric components after we calibrate the error - prone covariates. asymptotic properties of the proposed estimators are established. we also propose the profile least - square based ratio test and wald test to identify significant parametric and nonparametric components. to improve accuracy of the proposed tests for small or moderate sample sizes, a wild bootstrap version is also proposed to calculate the critical values. intensive simulation experiments are conducted to illustrate the proposed approaches. | arxiv:0903.0499 |
this thesis is dedicated to explore the feasibility of numerical calculations in the $ \ epsilon $ - - regime of qcd for the extraction of physical information. we apply two formulations of the ginsparg - wilson fermions the neuberger operator and the hypercube overlap operator to compute the observables of interest. as a main result we present the comparison of the distributions of the leading individual eigenvalues of the neuberger operator in qcd and the analytical predictions of chiral random matrix theory. we observe a good agreement as long as each side of the physical volume exceeds about $ l \ approx 1. 12 \ fm $. it turns out that this bound for $ l $ is generic and sets the size of the physical volume where the axial correlator behaves according to chiral perturbation theory. this allows us to compute a value for the pion decay constant $ f _ { \ pi } $. as an alternative procedure we only consider the contribution from the zero modes. here we are able to obtain an estimate for $ f _ { \ pi } $ and $ \ alpha $. as a theoretical development the l \ " uscher topology conserving gauge action is investigated. this enables us to sample the observables of interest in the $ \ epsilon $ - - regime without recomputing the index. we can report that a promising gauge action has been identified. | arxiv:hep-lat/0502001 |
we consider the consequences of the absence of birkhoff ' s theorem in theories of modified gravity. as an example, we calculate the gravitational force on a test particle due to a spherical mass shell in the dvali - gabadaze - porrati model ( dgp ). we show that unlike in general relativity, the force depends on the mass distribution. in particular, the gravitational force within a spherical mass shell depends on the geometric structure of the bulk, and is likely non - zero. | arxiv:0709.4391 |
in this paper, we show the existence and uniqueness of viscosity solution to the cauchy - dirichlet problem for a class of fully nonlinear parabolic equations. this extends recent results of eyssidieux - guedj - zeriahi. | arxiv:2201.12744 |
we propose an efficient free - space scheme to create single photons in a well - defined spatiotemporal mode. to that end, we first prepare a single source atom in an excited rydberg state. the source atom interacts with a large ensemble of ground - state atoms via a laser - mediated dipole - dipole exchange interaction. using an adiabatic passage with a chirped laser pulse, we produce a spatially extended spin wave of a single rydberg excitation in the ensemble, accompanied by the transition of the source atom to another rydberg state. the collective atomic excitation can then be converted to a propagating optical photon via a coherent coupling field. in contrast to previous approaches, our single - photon source does not rely on the strong coupling of a single emitter to a resonant cavity, nor does it require the heralding of collective excitation or complete rydberg blockade of multiple excitations in the atomic ensemble. | arxiv:1806.07094 |
wang et al. claim [ j. appl. phys. 125, 054504 ( 2019 ) ] that a current - carrying wire interacting with a magnetic core represents a memristor. here, we demonstrate that this claim is false. we first show that such memristor " discovery " is based on incorrect physics, which does not even capture basic properties of magnetic core materials, such as their magnetic hysteresis. moreover, the predictions of wang et al. ' s model contradict the experimental curves presented in their paper. additionally, the theoretical pinched hysteresis loops presented by wang et al. can not be reproduced if their model is used, and there are serious flaws in their " negative memristor " emulator design. finally, a simple gedanken experiment shows that the proposed $ \ phi $ - memristor would fail the memristor test we recently suggested in j. phys. d : appl. phys. 52, 01lt01 ( 2019 ). the device " discovered " by wang et al. is just an inductor with memory. | arxiv:1909.12464 |
a vortex in a superfluid gas inside an optical lattice can behave as a massive particle moving in a periodic potential and exhibiting quantum properties. in this letter we discuss these properties and show that the excitation of vortex motions in a two - dimensional lattice can lead to striking measurable changes in its dynamic response. it would be possible by means of bragg spectroscopy to carry out the first direct measurement of the effective vortex mass, the pinning to the underlying lattice, and the dissipative damping. | arxiv:cond-mat/0701439 |
nano - fabrication in silicon, arguably the most important material for modern technology, has been limited exclusively to its surface. existing lithographic methods cannot penetrate the wafer surface without altering it, whereas emerging laser - based subsurface or in - chip fabrication remains at > 1 micrometer resolution. in addition, available methods do not allow positioning or modulation with sub - micron precision deep inside the wafer. the fundamental difficulty of breaking these dimensional barriers are two - fold, i. e., complex nonlinear effects inside the wafer and the inherent diffraction limit for laser light. here, we overcome these challenges by using structured - laser - beams and exploiting preformed subsurface structures as seed, in order to establish the first controlled nano - fabrication capability inside silicon. we demonstrate buried nano - structures of feature sizes down to 100 nm + - 25 nm, with sub - wavelength and multi - dimensional control ; thereby improving the state - of - the - art by an order - of - magnitude. in order to showcase the photonic capabilities, we fabricated the first in - chip nano - photonic elements, i. e., nano - gratings with record diffraction efficiency and spectral control. the reported advance is an important step towards in - chip nano - photonic systems, micro - / nano - fluidics & nems / mems, and 3d electronic - photonic integration. | arxiv:2302.13105 |
we study the inclusive semileptonic rare decay $ b \ to s l ^ + l ^ - $ in minimal supergravity model ( msugra ). if tan $ \ beta $ is large, down - type quark mass matrices and their yukawa couplings cannot be diagonalized at the same basis. this induces the flavor violating neutral higgs boson couplings. these couplings contribute significantly to decay $ b \ to s mu ^ + mu ^ - $ and $ b \ to s tau ^ + tau ^ - $, but negligible to $ b \ to s e ^ + e ^ - $ decay because of its negligible $ m _ e $ mass. the ratio $ r \ equiv b ( b \ to s mu ^ + mu ^ - ) / b ( b \ to s e ^ + e ^ - ) $ can be very different from its corresponding value in the standard model. we find that part of parameter space can accommodate a large r value, and that maximum r value can be larger than 2. we also present our results in $ b \ to s tau ^ + tau ^ - $ decay channel. although it can be not detected now, it is potentially a new channel for the future observation of new physics. | arxiv:hep-ph/0304248 |
elements pasted on the ferrite layer. fss are used for filtration and microwave absorption. = = = radar stealth countermeasures and limits = = = = = = = low - frequency radar = = = = shaping offers far fewer stealth advantages against low - frequency radar. if the radar wavelength is roughly twice the size of the target, a half - wave resonance effect can still generate a significant return. however, low - frequency radar is limited by lack of available frequencies ( many are heavily used by other systems ), by lack of accuracy of the diffraction - limited systems given their long wavelengths, and by the radar ' s size, making it difficult to transport. a long - wave radar may detect a target and roughly locate it, but not provide enough information to identify it, target it with weapons, or even to guide a fighter to it. = = = = multiple emitters = = = = stealth aircraft attempt to minimize all radar reflections, but are specifically designed to avoid reflecting radar waves back in the direction they came from ( since in most cases a radar emitter and receiver are in the same location ). they are less able to minimize radar reflections in other directions. thus, detection can be better achieved if emitters are in different locations from receivers. one emitter separate from one receiver is termed bistatic radar ; one or more emitters separate from more than one receiver is termed multistatic radar. proposals exist to use reflections from emitters such as civilian radio transmitters, including cellular telephone radio towers. = = = = moore ' s law = = = = by moore ' s law the processing power behind radar systems is rising over time. this will eventually erode the ability of physical stealth to hide vehicles. = = = = ship wakes and spray = = = = synthetic aperture sidescan radars can be used to detect the location and heading of ships from their wake patterns. these are detectable from orbit. when a ship moves through a seaway it throws up a cloud of spray which can be detected by radar. = = acoustics = = acoustic stealth plays a primary role for submarines and ground vehicles. submarines use extensive rubber mountings to isolate, damp, and avoid mechanical noises that can reveal locations to underwater passive sonar arrays. early stealth observation aircraft used slow - turning propellers to avoid being heard by enemy troops below. stealth aircraft that stay subsonic can avoid being tracked by sonic boom. the presence of supersonic and jet - powered stealth aircraft such as the sr - 71 blackbird indicates that | https://en.wikipedia.org/wiki/Stealth_technology |
we prove that for every exact discrete group $ \ gamma $, there is an intermediate c * - algebra between the reduced group c * - algebra and the intersection of the group von neumann algebra and the uniform roe algebra which is realized as the intersection of a decreasing sequence of isomorphs of the cuntz algebra $ \ mathcal { o } _ 2 $. in particular, when $ \ gamma $ has the ap ( approximation property ), the reduced group c * - algebra is realized in this way. we also study extensions of the reduced free group c * - algebras and show that any exact absorbing or unital absorbing extension of it by any stable separable nuclear c * - algebra is realized in this way. | arxiv:1410.8347 |
africa has a very low doctor - to - patient ratio. at very busy clinics, doctors could see 30 + patients per day - - a heavy patient burden compared with developed countries - - but productivity tools such as clinical automatic speech recognition ( asr ) are lacking for these overworked clinicians. however, clinical asr is mature, even ubiquitous, in developed nations, and clinician - reported performance of commercial clinical asr systems is generally satisfactory. furthermore, the recent performance of general domain asr is approaching human accuracy. however, several gaps exist. several publications have highlighted racial bias with speech - to - text algorithms and performance on minority accents lags significantly. to our knowledge, there is no publicly available research or benchmark on accented african clinical asr, and speech data is non - existent for the majority of african accents. we release afrispeech, 200hrs of pan - african english speech, 67, 577 clips from 2, 463 unique speakers across 120 indigenous accents from 13 countries for clinical and general domain asr, a benchmark test set, with publicly available pre - trained models with sota performance on the afrispeech benchmark. | arxiv:2310.00274 |
we extend previous calculations of leading - order correlation functions of spin - 0 and spin - 1 light quarkonium hybrids to include qcd condensates of dimensions five and six, with a view to improving the stability of qcd sum - rules analyses in previously unstable channels. based on these calculations, prior analyses in the literature, and its phenomenological importance, we identify the exotic $ j ^ { pc } = 0 ^ { + - } $ channel as the most promising for detailed study. using gaussian sum - rules constrained by the h \ " older inequality, we calculate masses of light ( nonstrange and strange ) quarkonium hybrid mesons with $ j ^ { pc } = 0 ^ { + - } $. we consider single narrow, single wide, and double narrow resonance models, and find that the double narrow resonance model yields the best agreement between qcd and phenomenology. in both non - strange and strange cases, we find hybrid masses of $ 2. 60 $ gev and $ 3. 57 $ gev. | arxiv:1806.02465 |
the $ 1s $ level shift in kaonic deuterium was calculated using coulomb sturmian expansion of faddeev equations. the convergence of the method yields an $ \ sim \ 1 \ ev $ accuracy for the level shifts. we used three different, realistic, multichannel $ \ bar { k } n $ interactions reproducing all known experimental two - body $ \ bar { k } n $ data. the different results suggest, that the level shift should be in the range $ \ delta e \ sim ( 800 \ pm30 ) - ( 480 \ pm20 ) { \ rm i } \ \ ev $. the ( almost ) exact level shifts were compared with values, given by the commonly used approximations. | arxiv:1608.01802 |
charge exchange is an atomic process that primarily occurs at interfaces between the neutral and ionized gas. the study of the process has been carried out on three levels : the theoretical calculation of the cross sections, the laboratory measurements of reaction rates and line strengths, and the observational constraints using celestial objects. for a long time in the past, the status of astrophysical observations in the x - ray band lagged behind the other two aspects until the discovery of x - ray from a comet was made in 1996, which changed the research landscape. recent observational evidence suggests that charge exchange has been seen or can be expected from a surprisingly broad range of locations, from the earth ' s exosphere to the large - scale structures of the universe. the rapid development of high - resolution x - ray spectroscopy, in particular the non - dispersive micro - calorimeters, is paving the way to revolutionary new science possibilities both in the laboratory and astrophysics. this chapter summarizes the current knowledge of charge exchange and its relevance on astrophysics, especially x - ray spectroscopy. | arxiv:2301.11335 |
we study the feasibility of using neutrino - electron elastic scattering to measure the neutrino flux in the dune neutrino oscillation experiment. the neutrino - electron scattering cross section is precisely known, and the kinematics of the reaction allow determination of the incoming neutrino energy by precise measurement of the energy and angle of the recoiling electron. for several possible near detectors, we perform an analysis of their ability to measure neutrino flux in the presence of backgrounds and uncertainties. with realistic assumptions about detector masses, we find that a liquid argon detector, even with limitations due to angular resolution, is able to perform better than less dense detectors with more precise event - by - event neutrino energy measurements. we find that the absolute flux normalization uncertainty can be reduced from ~ 8 % to ~ 2 %, and the uncertainty on the flux shape can be reduced by ~ 20 - 30 %. | arxiv:1910.10996 |
two recent studies of the evolution of the isoscalar giant monopole resonance ( isgmr ) within the calcium isotope chain report conflicting results. one study suggests that the monopole resonance energy, and thus the incompressibility of the nucleus $ k _ { a } $ increase with mass, which implies that $ k _ { \ tau } $, the asymmetry term in the nuclear incompressibility, has a positive value. the other study reports a weak decreasing trend of the energy moments, resulting in a generally accepted negative value for $ k _ { \ tau } $. an independent measurement of the central region of the isgmr in the ca isotope chain is provided to gain a better understanding of the origin of possible systematic trends. inelastically scattered $ \ alpha $ particles from a range of calcium targets ( $ \ mathrm { ^ { 40, 42, 44, 48 } ca } $ ), observed at small scattering angles including 0 $ ^ \ circ $, were momentum analyzed in the k600 magnetic spectrometer at ithemba labs, south africa. monopole strengths spanning an excitation - energy range between 9. 5 and 25. 5 mev were obtained using the difference - of - spectra ( dos ) technique. the structure of the $ e0 $ strength distributions of $ ^ { 40, 42, 44 } $ ca agrees well with the results from the previous measurement that supports a weak decreasing trend of the energy moments, while no two datasets agree in the case of $ ^ { 48 } $ ca. despite the variation in the structural character of $ e0 $ strength distribution from different studies, we find for all datasets that the moment ratios, calculated from the isgmr strength in the excitation - energy range that defines the main resonance region, display at best only a weak systematic sensitivity to a mass increase. different trends observed in the nuclear incompressibility are caused by contributions to the $ e0 $ strength outside of the main resonance region, and in particular for high excitation energies. | arxiv:2202.00722 |
the pythia event generator is used in several contexts to study hadron and lepton interactions, notably $ pp $ and $ p \ bar { p } $ collisions. in this article we extend the hadronic modelling to encompass the collision of a wide range of hadrons $ h $ with either a proton or a neutron, or with a simplified model of nuclear matter. to this end we model $ hp $ total and partial cross sections as a function of energy, and introduce new parton distribution functions for a wide range of hadrons, as required for a proper modelling of multiparton interactions. the potential usefulness of the framework is illustrated by a simple study of the evolution of cosmic rays in the atmosphere, and by an even simpler one of shower evolution in a solid detector material. the new code will be made available for future applications. | arxiv:2108.03481 |
we prove the local langlands conjecture for the exceptional group $ g _ 2 ( f ) $ where $ f $ is a non - archimedean local field of characteristic zero. | arxiv:2209.07346 |
due to strong mode - confinement, long propagation - distance, and unique tunability, graphene plasmons have been widely explored in the mid - infrared and terahertz windows. however, it remains a big challenge to push graphene plasmons to shorter wavelengths in order to integrate graphene plasmon concepts with existing mature technologies in the near - infrared region. we investigate localized graphene plasmons supported by graphene nanodisks and experimentally demonstrated graphene plasmon working at 2 { \ mu } m with the aid of a fully scalable block copolymer self - assembly method. our results show a promising way to promote graphene plasmons for both fundamental studies and potential applications in the near - infrared window. | arxiv:1606.02471 |
in this paper a malliavin calculus for l \ ' evy processes based on a family of true derivative operators is developed. the starting point is an extension to l \ ' evy processes of the pioneering paper by carlen and pardoux [ 8 ] for the poisson process, and our approach includes also the classical malliavin derivative for gaussian processes. we obtain a sufficient condition for the absolute continuity of functionals of the l \ ' evy process. as an application, we analyze the absolute continuity of the law of the solution of some stochastic differential equations. | arxiv:1210.1156 |
in this paper, we begin by introducing clairaut riemannian warped product maps and establish the condition under which a regular curve becomes a geodesic. we obtain the conditions for a riemannian warped product map to be clairaut riemannian warped product map followed by ricci curvature. further, we study the ricci soliton structure on a riemannian warped product manifold using curvature tensor. we examine the bochner type formulae for clairaut riemannian warped product map and construct a supporting example. furthermore, we extend the study to introduce and examine some geometric aspects of conformal riemannian warped product maps. we derive the integral formula for scalar curvature of conformal riemannian warped product map. finally, we construct an example for conformal riemannian warped product map. | arxiv:2505.01865 |
we consider deformations of a pair $ ( x, \ partial x ) $, where $ x $ is an affine toric gorenstein variety and $ \ partial x $ is its boundary. we compute the tangent and obstruction space for the corresponding deformation functor and for an admissible lattice degree $ m $ we construct the miniversal deformation of $ ( x, \ partial x ) $ in degrees $ - km $, for all $ k \ in \ mathbb { n } $ together. this in particular generalizes altmann ' s construction of the miniversal deformation of an isolated gorenstein toric singularity to an arbitrary non - isolated gorenstein toric singularity. we see that it is more natural to work with deformations of a pair $ ( x, \ partial x ) $ rather than only with deformations of $ x $, since many computations are in fact easier. | arxiv:2006.12960 |
we study the structure of stationary non equilibrium states for interacting particle systems from a microscopic viewpoint. in particular we discuss two different discrete geometric constructions. we apply both of them to determine non reversible transition rates corresponding to a fixed invariant measure. the first one uses the equivalence of this problem with the construction of divergence free flows on the transition graph. since divergence free flows are characterized by cyclic decompositions we can generate families of models from elementary cycles on the configuration space. the second construction is a functional discrete hodge decomposition for translational covariant discrete vector fields. according to this, for example, the instantaneous current of any interacting particle system on a finite torus can be canonically decomposed in a gradient part, a circulation term and an harmonic component. all the three components are associated to functions on the configuration space. this decomposition is unique and constructive. the stationary condition can be interpreted as an orthogonality condition with respect to an harmonic discrete vector field and we use this decomposition to construct models having a fixed invariant measure. | arxiv:1703.02418 |
pre - trained language models are still far from human performance in tasks that need understanding of properties ( e. g. appearance, measurable quantity ) and affordances of everyday objects in the real world since the text lacks such information due to reporting bias. in this work, we study whether integrating visual knowledge into a language model can fill the gap. we investigate two types of knowledge transfer : ( 1 ) text knowledge transfer using image captions that may contain enriched visual knowledge and ( 2 ) cross - modal knowledge transfer using both images and captions with vision - language training objectives. on 5 downstream tasks that may need visual knowledge to solve the problem, we perform extensive empirical comparisons over the presented objectives. our experiments show that visual knowledge transfer can improve performance in both low - resource and fully supervised settings. | arxiv:2203.07519 |
we prove that the airy process, a ( t ), locally fluctuates like a brownian motion. in the same spirit we also show that in a certain scaling limit, the so called discrete polynuclear growth ( png ) process behaves like a brownian motion. | arxiv:math/0701880 |
the vacuum tunneling rate $ \ gamma $ from the effective action is a key to studying the cosmological first - order phase transition ( fopt ). one solid way to compute the $ \ gamma $ is to start with the derivative expansion of the effective action and solve the bounce equation numerically. in this process, the renormalization factor $ z $ of the tunneling field may play a center rule, which is not considered in existing packages. therefore, we present a \ texttt { mathematica } package \ vt to compute the bounce action with or without the renormalization factor. applying the \ vt package, we find that the presence of $ z $ has a significant impact on the action, as well on the tunneling path. we provide some concrete examples to demonstrate the difference between the solution with and without the renormalization factor, both in the action and tunneling path. this package is based on the modified shooting and path deformation method. we also made some optimizations for the super - cooling phase transition ( thick wall scenario ), in which other numerical package works poorly. this package works as long as the expressions can give values of the potential and the renormalization at a certain field point. this means the input potential and the renormalization can be merely numerical quantities without analytical expressions. the computation time can be as short as 1 second in single - field tunneling and several seconds in multi - field cases. | arxiv:2501.15236 |
introducing a new notion of generalized suitable weak solutions, we first prove validity of the energy inequality for such a class of weak solutions to the navier - stokes equations in the whole space $ \ mathbb { r } ^ n $. although we need certain growth condition on the pressure, we may treat the class even with infinite energy quantity except for the initial velocity. we next handle the equation for vorticity in 2d unbounded domains. under a certain condition on the asymptotic behavior at infinity, we prove that the vorticity and its gradient of solutions are both globally square integrable. as their applications, loiuville - type theorems are obtained. | arxiv:1708.07618 |
this paper investigates the overload problem of a single congested router in tcp ( transmission control protocol ) networks. to cope with the congestion phenomenon, we design a feedback control based on a multiple time - delays model of the set tcp / aqm ( active queue management ). indeed, using robust control tools, especially in the quadratic separation framework, the tcp / aqm model is rewritten as an intercon - nected system and a structured state feedback is constructed to stabilize the network variables. finally, we illustrate the proposed methodology with a numerical example and simulations using ns - 2 simulator. | arxiv:0902.0919 |
wildland fire smoke contains hazardous levels of fine particulate matter pm2. 5, a pollutant shown to adversely effect health. estimating fire attributable pm2. 5 concentrations is key to quantifying the impact on air quality and subsequent health burden. this is a challenging problem since only total pm2. 5 is measured at monitoring stations and both fire - attributable pm2. 5 and pm2. 5 from all other sources are correlated in space and time. we propose a framework for estimating fire - contributed pm2. 5 and pm2. 5 from all other sources using a novel causal inference framework and bias - adjusted chemical model representations of pm2. 5 under counterfactual scenarios. the chemical model representation of pm2. 5 for this analysis is simulated using community multi - scale air quality modeling system ( cmaq ), run with and without fire emissions across the contiguous u. s. for the 2008 - 2012 wildfire seasons. the cmaq output is calibrated with observations from monitoring sites for the same spatial domain and time period. we use a bayesian model that accounts for spatial variation to estimate the effect of wildland fires on pm2. 5 and state assumptions under which the estimate has a valid causal interpretation. our results include estimates of absolute, relative and cumulative contributions of wildfire smoke to pm2. 5 for the contiguous u. s. additionally, we compute the health burden associated with the pm2. 5 attributable to wildfire smoke. | arxiv:2003.06037 |
because primordial black holes ( pbhs ) evaporate into all particle species in nature, pbhs may emit several dark matter ( dm ) particle species with specific mass spectra. we assume that pbhs are the only source of dms, and dms only interact with the standard model particles gravitationally. we show a relation between the number of dm particle species $ n _ { \ rm dm } $ and initial pbh density $ \ beta $ and mass $ m _ { \ rm bh } ^ { \ rm in } $. $ \ beta $ - $ m _ { \ rm bh } ^ { \ rm in } $ curves for different $ n _ { \ rm dm } $ tend to overlap with each other for heavy initial pbhs. we also show that the allowed region of dm masses for multiple dm. | arxiv:2204.07898 |
in tabular multi - agent reinforcement learning with average - cost criterion, a team of agents sequentially interacts with the environment and observes local incentives. we focus on the case that the global reward is a sum of local rewards, the joint policy factorizes into agents ' marginals, and full state observability. to date, few global optimality guarantees exist even for this simple setting, as most results yield convergence to stationarity for parameterized policies in large / possibly continuous spaces. to solidify the foundations of marl, we build upon linear programming ( lp ) reformulations, for which stochastic primal - dual methods yields a model - free approach to achieve \ emph { optimal sample complexity } in the centralized case. we develop multi - agent extensions, whereby agents solve their local saddle point problems and then perform local weighted averaging. we establish that the sample complexity to obtain near - globally optimal solutions matches tight dependencies on the cardinality of the state and action spaces, and exhibits classical scalings with respect to the network in accordance with multi - agent optimization. experiments corroborate these results in practice. | arxiv:2110.12929 |
this paper expands the work on distributionally robust newsvendor to incorporate moment constraints. the use of wasserstein distance as the ambiguity measure is preserved. the infinite dimensional primal problem is formulated ; problem of moments duality is invoked to derive the simpler finite dimensional dual problem. an important research question is : how does distributional ambiguity affect the optimal order quantity and the corresponding profits / costs? to investigate this, some theory is developed and a case study in auto sales is performed. we conclude with some comments on directions for further research. | arxiv:2010.16369 |
we investigate the connection between the hi ~ content, sfr and environment of galaxies using a hydrodynamic simulation that incorporates scaling relations for galactic wind and a heuristic halo mass - based quenching prescription. we run two zoom - in simulations of galaxy groups with $ m _ { halo } > 10 ^ { 13 } m _ \ odot $ at z = 0, selected to have quiet merger histories. we track galaxies as they become satellites, and compute the delay time $ \ tau _ { d } $ during which the satellites are similar to central galaxies at a given stellar mass, and a fading time $ \ tau _ { f } $ during which satellites go from gas - rich and star - forming to gas - poor and quiescent. we find $ 0. 7 < \ tau _ { d } < 3 $ gyr at $ z = 0 $, and depends inversely on the satellite halo mass at infall. at z ~ 1 we find ~ $ 0. 3 < \ tau _ { d } < 2 $ gyr, broadly consistent with a positive correlation with the hubble time. for a given halo mass, lower stellar mass galaxies at infall time have higher $ \ tau _ { d } $. we generally find $ \ tau _ { f } \ ll \ tau _ { d } $, ranging between ~ 150 myr at z ~ 0 and ~ 80 myr at z ~ 1 based on linear interpolation, with some uncertainty because they are smaller than our simulation output frequency ( $ 200 - 300 $ myr ). $ \ tau _ { f } $ has no obvious dependency on infall halo mass. both timescales show little difference between hi depletion and sf quenching, indicating that using up the gas reservoir by star formation without refilling is the main mechanism to transform satellite galaxies at these halo masses. at a given physical distance from the center of the main halo of interest, higher redshift galaxies have on average higher cold gas content, but the ratio of gas ( hi or h $ _ 2 $ ) to star formation rate is similar, indicating that star formation is consistently fed through reservoirs of hi then h $ _ 2 $. for a given amount of hi, galaxies have shorter consumption times in more massive halo structures. | arxiv:1811.11613 |
effective field theory allows for a systematic and model - independent derivation of the forces between nucleons in harmony with the symmetries of quantum chromodynamics. we review the foundations of this approach and discuss its application for light nuclei at various resolution scales. the extension of this approach to many - body systems is briefly sketched. | arxiv:0811.1338 |
depression and anxiety are psychiatric disorders that are observed in many areas of everyday life. for example, these disorders manifest themselves somewhat frequently in texts written by nondiagnosed users in social media. however, detecting users with these conditions is not a straightforward task as they may not explicitly talk about their mental state, and if they do, contextual cues such as immediacy must be taken into account. when available, linguistic flags pointing to probable anxiety or depression could be used by medical experts to write better guidelines and treatments. in this paper, we develop a dataset designed to foster research in depression and anxiety detection in twitter, framing the detection task as a binary tweet classification problem. we then apply state - of - the - art classification models to this dataset, providing a competitive set of baselines alongside qualitative error analysis. our results show that language models perform reasonably well, and better than more traditional baselines. nonetheless, there is clear room for improvement, particularly with unbalanced training sets and in cases where seemingly obvious linguistic cues ( keywords ) are used counter - intuitively. | arxiv:2011.05249 |
tor is currently one of the more popular systems for anonymizing near real - time communications on the internet. recently, borisov et al. proposed a denial of service based attack on tor ( and related systems ) that significantly increases the probability of compromising the anonymity provided. in this paper, we analyze the effectiveness of the attack using both an analytic model and simulation. we also describe two algorithms for detecting such attacks, one deterministic and proved correct, the other probabilistic and verified in simulation. | arxiv:1110.5395 |
multi - robot assembly systems are becoming increasingly appealing in manufacturing due to their ability to automatically, flexibly, and quickly construct desired structural designs. however, effectively planning for these systems in a manner that ensures each robot is simultaneously productive, and not idle, is challenging due to ( 1 ) the close proximity that the robots must operate in to manipulate the structure and ( 2 ) the inherent structural partial orderings on when each part can be installed. in this paper, we present a task and motion planning framework that jointly plans safe, low - makespan plans for a team of robots to assemble complex spatial structures. our framework takes a hierarchical approach that, at the high level, uses mixed - integer linear programs to compute an abstract plan comprised of an allocation of robots to tasks subject to precedence constraints and, at the low level, builds on a state - of - the - art algorithm for multi - agent path finding to plan collision - free robot motions that realize this abstract plan. critical to our approach is the inclusion of certain collision constraints and movement durations during high - level planning, which better informs the search for abstract plans that are likely to be both feasible and low - makespan while keeping the search tractable. we demonstrate our planning system on several challenging assembly domains with several ( sometimes heterogeneous ) robots with grippers or suction plates for assembling structures with up to 23 objects involving lego bricks, bars, plates, or irregularly shaped blocks. | arxiv:2203.02475 |
we study turbulence and bose - einstein condensation ( bec ) within the two - dimensional gross - pitaevski ( gp ) model. in the present work, we compute decaying gp turbulence in order to establish whether bec can occur without forcing and if there is an intensity threshold for this process. we use the wavenumber - frequency plots which allow us to clearly separate the condensate and the wave components and, therefore, to conclude if bec is present. we observe that bec in such a system happens even for very weakly nonlinear initial conditions without any visible threshold. bec arises via a growing phase coherence due to anihilation of phase defects / vortices. we study this process by tracking of propagating vortex pairs. the pairs loose momentum by scattering the background sound, which results in gradual decrease of the distance between the vortices. occasionally, vortex pairs collide with a third vortex thereby emitting sound, which can lead to more sudden shrinking of the pairs. after the vortex anihilation the pulse propagates further as a dark soliton, and it eventually bursts creating a shock. | arxiv:nlin/0610016 |
the higher microwave band 3 – 6 ghz, and millimeter wave band, around 28 and 39 ghz. since these frequencies have a shorter range than previous cellphone bands, the cells will be smaller than the cells in previous cellular networks which could be many miles across. millimeter - wave cells will only be a few blocks long, and instead of a cell base station and antenna tower, they will have many small antennas attached to utility poles and buildings. satellite phone ( satphone ) – a portable wireless telephone similar to a cell phone, connected to the telephone network through a radio link to an orbiting communications satellite instead of through cell towers. they are more expensive than cell phones ; but their advantage is that, unlike a cell phone which is limited to areas covered by cell towers, satphones can be used over most or all of the geographical area of the earth. in order for the phone to communicate with a satellite using a small omnidirectional antenna, first - generation systems use satellites in low earth orbit, about 400 – 700 miles ( 640 – 1, 100 km ) above the surface. with an orbital period of about 100 minutes, a satellite can only be in view of a phone for about 4 – 15 minutes, so the call is " handed off " to another satellite when one passes beyond the local horizon. therefore, large numbers of satellites, about 40 to 70, are required to ensure that at least one satellite is in view continuously from each point on earth. other satphone systems use satellites in geostationary orbit in which only a few satellites are needed, but these cannot be used at high latitudes because of terrestrial interference. cordless phone – a landline telephone in which the handset is portable and communicates with the rest of the phone by a short - range full duplex radio link, instead of being attached by a cord. both the handset and the base station have low - power radio transceivers that handle the short - range bidirectional radio link. as of 2022, cordless phones in most nations use the dect transmission standard. land mobile radio system – short - range mobile or portable half - duplex radio transceivers operating in the vhf or uhf band that can be used without a license. they are often installed in vehicles, with the mobile units communicating with a dispatcher at a fixed base station. special systems with reserved frequencies are used by first responder services ; police, fire, ambulance, and emergency services, and other government services. other systems are made for | https://en.wikipedia.org/wiki/Radio |
hate speech poses a significant threat to social harmony. over the past two years, indonesia has seen a ten - fold increase in the online hate speech ratio, underscoring the urgent need for effective detection mechanisms. however, progress is hindered by the limited availability of labeled data for indonesian texts. the condition is even worse for marginalized minorities, such as shia, lgbtq, and other ethnic minorities because hate speech is underreported and less understood by detection tools. furthermore, the lack of accommodation for subjectivity in current datasets compounds this issue. to address this, we introduce indotoxic2024, a comprehensive indonesian hate speech and toxicity classification dataset. comprising 43, 692 entries annotated by 19 diverse individuals, the dataset focuses on texts targeting vulnerable groups in indonesia, specifically during the hottest political event in the country : the presidential election. we establish baselines for seven binary classification tasks, achieving a macro - f1 score of 0. 78 with a bert model ( indobertweet ) fine - tuned for hate speech classification. furthermore, we demonstrate how incorporating demographic information can enhance the zero - shot performance of the large language model, gpt - 3. 5 - turbo. however, we also caution that an overemphasis on demographic information can negatively impact the fine - tuned model performance due to data fragmentation. | arxiv:2406.19349 |
we consider aspects of the population dynamics, inside a bound domain, of diffusing agents carrying an attribute which is stochastically destroyed upon contact with the boundary. the normal mode analysis of the relevant helmholtz equation under the partially absorbing, but uniform, boundary condition provides a starting framework in understanding detailed evolution dynamics of the attribute in the time domain. in particular, the boundary - localized depletion has been widely employed in practical applications that depend on geometry of various porous media such as rocks, cement, bones, and cheese. while direct relationship between the pore geometry and the diffusion - relaxation spectrum forms the basis for such applications and has been extensively studied, relatively less attention has been paid to the spatial variation of the boundary condition. in this work, we focus on the way the pore geometry and the inhomogeneous depletion strength of the boundary become intertwined and thus obscure the direct relationship between the spectrum and the geometry. it is often impossible to gauge experimentally the degree to which such interference occur. we fill this gap by perturbatively incorporating classes of spatially - varying boundary conditions and derive their consequences that are observable through numerical simulations or controlled experiments on glass bead packs and artificially fabricated porous media. we identify features of the spectrum that are most sensitive to the inhomogeneity and apply the method to the spherical pore with a simple hemi - spherical binary distribution of the depletion strength and obtain bounds for the induced change in the slowest relaxation mode. | arxiv:0903.1655 |
this study investigates whether large language models, specifically gpt4, can match human capabilities in analogical reasoning within strategic decision making contexts. using a novel experimental design involving source to target matching, we find that gpt4 achieves high recall by retrieving all plausible analogies but suffers from low precision, frequently applying incorrect analogies based on superficial similarities. in contrast, human participants exhibit high precision but low recall, selecting fewer analogies yet with stronger causal alignment. these findings advance theory by identifying matching, the evaluative phase of analogical reasoning, as a distinct step that requires accurate causal mapping beyond simple retrieval. while current llms are proficient in generating candidate analogies, humans maintain a comparative advantage in recognizing deep structural similarities across domains. error analysis reveals that ai errors arise from surface level matching, whereas human errors stem from misinterpretations of causal structure. taken together, the results suggest a productive division of labor in ai assisted organizational decision making where llms may serve as broad analogy generators, while humans act as critical evaluators, applying the most contextually appropriate analogies to strategic problems. | arxiv:2505.00603 |
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