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for fields that vary slowly on the scale of the lightest mass the logarithm of the vacuum functional can be expanded as a sum of local functionals. for yang - mills theory the leading term in the expansion dominates large distance effects and leads to an area law for the wilson loop. however, this expansion cannot be expected to converge for fields that vary more rapidly. by studying the analyticity of the vacuum functional under scale transformations we show how to re - sum this series so as to reconstruct the vacuum functional for arbitrary fields. | arxiv:hep-th/9510188 |
when analyzing the spread of viruses, epidemiologists often need to identify the location of infected hosts. this information can be found in public databases, such as genbank, however, information provided in these databases are usually limited to the country or state level. more fine - grained localization information requires phylogeographers to manually read relevant scientific articles. in this work we propose an approach to automate the process of place name identification from medical ( epidemiology ) articles. the focus of this paper is to propose a deep learning based model for toponym detection and experiment with the use of external linguistic features and domain specific information. the model was evaluated using a collection of 105 epidemiology articles from pubmed central provided by the recent semeval task 12. our best detection model achieves an f1 score of $ 80. 13 \ % $, a significant improvement compared to the state of the art of $ 69. 84 \ % $. these results underline the importance of domain specific embedding as well as specific linguistic features in toponym detection in medical journals. | arxiv:1904.11018 |
the fault tolerance of quantum devices requires on - par contributions from error - correcting codes and suitable decoders. one of the most explored error - correcting codes is the family of quantum low - density parity check ( qldpc ) codes. although faster than many of the reported decoders for qldpc codes, iterative decoders fail due to the colossal degeneracy and short cycles intrinsic to these codes. we present a strategy to improve the performance of the iterative decoders based on a collaborative way to use the message passing of the iterative decoders and check node removal from the code ' s tanner graph. we use the concept of bit separation and generalize it to qubit separation. this gives us a metric to analyze and improve the decoder ' s performance towards harmful configurations of qldpc codes. we present a simple decoding architecture to overcome iterative decoding failures by increasing the separation of trapped qubits without incurring any significant overhead. | arxiv:2501.08036 |
a vector meson exchange model based on effective lagrangians is used to build the meson - - baryon interaction in the charm $ + 1 $, strangeness $ - 2 $ and isospin $ 0 $ sector. the s - wave scattering amplitudes resulting from the unitarization in coupled - channels show two resonances with masses and widths that are in very good agreement with those of the experimental $ \ omega _ c ( 3050 ) ^ 0 $ and $ \ omega _ c ( 3090 ) ^ 0 $ states observed by the lhcb collaboration. the interpretation of these resonances as pseudoscalar meson - - baryon molecules would mean the assignment $ j ^ p = 1 / 2 ^ - $ to their spin - - parity. | arxiv:1812.03898 |
in this study, we extend our previous global analysis of nuclear - modified transverse momentum distribution functions ( ntmds ) to also consider the nuclear - modified collinear fragmentation function. our methodology incorporates the global set of experimental data from both drell - yan production and semi - inclusive deep inelastic scattering. through a comprehensive global extraction of these distributions, we demonstrate the effectiveness of this extension by strongly describing the entire global dataset. a focal point of this paper is the impact of recent jefferson lab measurements. most notably, to simultaneously describe experimental data at jefferson lab and hermes we find that it is necessary to introduce a parameter which accounts for the non - perturbative scale evolution of the ntmds. additionally, we assess the kinematic coverage of the experimental data and provide insights into experimental opportunities at jefferson lab, future electron - ion colliders, rhic, and the lhc. these opportunities have the potential to significantly enhance and refine global analyses of nuclear - modified tmds, contributing to a deeper understanding of the structure of cold nuclear matter. | arxiv:2312.09226 |
we introduce m $ ^ 2 $ hub, a toolkit for advancing machine learning in materials discovery. machine learning has achieved remarkable progress in modeling molecular structures, especially biomolecules for drug discovery. however, the development of machine learning approaches for modeling materials structures lag behind, which is partly due to the lack of an integrated platform that enables access to diverse tasks for materials discovery. to bridge this gap, m $ ^ 2 $ hub will enable easy access to materials discovery tasks, datasets, machine learning methods, evaluations, and benchmark results that cover the entire workflow. specifically, the first release of m $ ^ 2 $ hub focuses on three key stages in materials discovery : virtual screening, inverse design, and molecular simulation, including 9 datasets that covers 6 types of materials with 56 tasks across 8 types of material properties. we further provide 2 synthetic datasets for the purpose of generative tasks on materials. in addition to random data splits, we also provide 3 additional data partitions to reflect the real - world materials discovery scenarios. state - of - the - art machine learning methods ( including those are suitable for materials structures but never compared in the literature ) are benchmarked on representative tasks. our codes and library are publicly available at https : / / github. com / yuanqidu / m2hub. | arxiv:2307.05378 |
from the analysis of sizes of approximately 130 small icosahedral viruses we find that there is a typical structural capsid protein, having a mean diameter of 5 nm and a mean thickness of 3 nm, with more than two thirds of the analyzed capsid proteins having thicknesses between 2 nm and 4 nm. to investigate whether, in addition to the fairly conserved geometry, capsid proteins show similarities in the way they interact with one another, we examined the shapes of the capsids in detail. we classified them numerically according to their similarity to sphere and icosahedron and an interpolating set of shapes in between, all of them obtained from the theory of elasticity of shells. in order to make a unique and straightforward connection between an idealized, numerically calculated shape of an elastic shell and a capsid, we devised a special shape fitting procedure, the outcome of which is the idealized elastic shape fitting the capsid best. using such a procedure we performed statistical analysis of a series of virus shapes and we found similarities between the capsid elastic properties of even very different viruses. as we explain in the paper, there are both structural and functional reasons for the convergence of protein sizes and capsid elastic properties. our work presents a specific quantitative scheme to estimate relatedness between different proteins based on the details of the ( quaternary ) shape they form ( capsid ). as such, it may provide an information complementary to the one obtained from the studies of other types of protein similarity, such as the overall composition of structural elements, topology of the folded protein backbone, and sequence similarity. | arxiv:1210.0332 |
we investigate sub - gap transport through a single - level quantum dot tunnel coupled to one superconducting and two normal - conducting leads. despite the tendency of a large charging energy to suppress the equilibrium proximity effect, a finite andreev current through the dot can be achieved in non - equilibrium situations. we propose two schemes to identify non - local andreev transport. in one of them, the presence of strong coulomb interaction leads to negative values of the non - local conductance as a clear signal of non - local andreev transport. | arxiv:0806.0237 |
convergence of a system of particles, interacting with a fluid, to navier - stokes - vlasov - fokker - planck system is studied. the interaction between particles and fluid is described by stokes drag force. the empirical measure of particles is proved to converge to the vlasov - fokker - planck component of the system and the velocity of the fluid coupled with the particles converges in the uniform topology to the the navier - stokes component. a new uniqueness result for the pde system is added. | arxiv:1811.07924 |
the boltzmann - langevin equation is used to relate the shot - noise power of a mesoscopic conductor to classical transmission probabilities at the fermi level. this semiclassical theory is applied to tunneling through n barriers in series. for n - > infinity the shot noise approaches one third of the poisson noise, independent of the transparency of the barriers. this confirms that the one - third suppression known to occur in diffusive conductors does not require phase coherence. | arxiv:cond-mat/9501004 |
we consider the hydrogen molecular ion $ h ^ + _ 2 $ in the presence of a strong homogeneous magnetic field. in this regime, the effective hamiltonian is almost one dimensional with a potential energy which looks like a sum of two dirac delta functions. this model is solvable, but not close enough to our exact hamiltonian for relevant strenght of the magnnetic field. however we show that the correct values of the equilibrium distance as well as the binding energy of the ground state of the ion, can be obtained when incorporating perturbative corrections up to second order. finally, we show that $ he _ 2 ^ { 3 + } $ exists for sufficiently large magnetic fields. | arxiv:math-ph/0403034 |
for locally convex spaces $ x $ and $ y $, the continuous linear map $ t : x \ to y $ is said to be bounded if it maps zero neighborhoods of $ x $ into bounded sets of $ y $. we denote $ ( x, y ) \ in \ mathcal { b } $ when every operator between $ x $ and $ y $ is bounded. for a banach space $ \ ell $ with a monotone norm $ \ | \ cdot \ | $ in which the canonical system $ ( e _ n ) $ forms an unconditional basis, we consider $ \ ell $ - k \ " othe spaces as a generalization of usual k \ " othe spaces. in this note, we characterize $ \ ell $ - k \ " othe spaces $ \ ell ( a _ { pn } ) $ and $ \ ell ( b _ { sm } ) $ such that $ ( \ ell ( a _ { pn } ), \ ell ( b _ { sm } ) ) \ in \ mathcal { b } $. a pair $ ( x, y ) $ is said to have the bounded factorization property, and denoted $ ( x, y ) \ in \ mathcal { bf } $, if each linear continuous operator $ t : x \ to x $ that factors over $ y $ is bounded. we also prove that injective tensor products of some classical k \ " othe spaces have bounded factorization property. | arxiv:1604.05298 |
the goal of this paper is to define the n - connected regions in the cartesian workspace of fully - parallel manipulators, i. e. the maximal regions where it is possible to execute point - to - point motions. the manipulators considered in this study may have multiple direct and inverse kinematic solutions. the n - connected regions are characterized by projection, onto the cartesian workspace, of the connected components of the reachable configuration space defined in the cartesian product of the cartesian space by the joint space. generalized octree models are used for the construction of all spaces. this study is illustrated with a simple planar fully - parallel manipulator. | arxiv:0705.1037 |
in this paper, we consider the topological interference management ( tim ) problem in a dynamic setting, where an adversary perturbs network topology to prevent the exploitation of sophisticated coding opportunities ( e. g., interference alignment ). focusing on a special class of network topology - chordal networks - we investigate algorithmic aspects of the tim problem under adversarial topology perturbation. in particular, given the adversarial perturbation with respect to edge insertion / deletion, we propose a dynamic graph coloring algorithm that allows for a constant number of re - coloring updates against each inserted / deleted edge to achieve the information - theoretic optimality. this is a sharp reduction of the general graph re - coloring, whose optimal number of updates scales as the size of the network, thanks to the delicate exploitation of the structural properties of chordal graph classes. | arxiv:2101.12673 |
we describe a new family of triply - periodic minimal surfaces with hexagonal symmetry, related to the quartz ( qtz ) and its dual ( the qzd net ). we provide a solution to the period problem and provide a parametrisation of these surfaces, that are not in the regular class, by the weierstrass - enneper formalism. we identified this analytical description of the surface by generating an area - minimising mesh interface from a pair of dual graphs ( qtz & qzd ) using the generalised voronoi construction of de campo, hyde and colleagues, followed by numerical identification of the flat point structure. this mechanism is not restricted to the specific pair of dual graphs, and should be applicable to a broader set of possible dual graph topologies and their corresponding minimal surfaces, if existent. | arxiv:1805.07034 |
valence band in narrow hgte quantum wells contains well - conductive dirac - like light holes at the $ \ gamma $ point and poorly conductive heavy hole subband located in the local valleys. here we propose and employ two methods to measure the density of states for these heavy holes. the first method uses a gate - recharging technique to measure thermodynamical entropy per particle. as the fermi level is tuned with gate voltage from light to heavy subband, the entropy increases dramatically, and the value of this increase gives an estimate for the density of states. the second method determines the density of states for heavy holes indirectly from the gate voltage dependence of the period of the shubnikov - de haas oscillations for light holes. the results obtained by both methods are in the reasonable agreement with each other. our approaches can be applied to measure large effective carrier masses in other two - dimensional gated systems. | arxiv:1907.07731 |
dynamical mean field theory ( dmft ) is one of the powerful computational approaches to study electron correlation effects in solid - state materials and molecules. its practical applicability is, however, limited by the quantity of numerical resources required for the solution of the underlying auxiliary anderson impurity model. here, the one - to - one mapping between electronic orbitals and the state of a qubit register suggests a significant computational advantage for the use of a quantum computer ( qc ) for solving this task. in this work we present a qc approach to solve a two - site dmft model based on the variational quantum eigensolver ( vqe ) algorithm. we analyse the propagation of stachastic and device errors through the algorithm and their effects on the calculated self - energy. therefore, we systematically compare results obtained on simulators with calculations on the ibmq ehningen qc hardware. we suggest a means to overcome unphysical features in the self - energy which already result from purely stochastic noise. based heron, we demonstrate the feasibility to obtain self - consistent results of the two - site dmft model based on vqe simulations with a finite number of shots. | arxiv:2311.10402 |
we consider a generalization of the dicke model. it describes localized, physically separated, saturable excitations, such as excitons bound on impurities, coupled to a single long - lived mode of an optical cavity. we consider the thermal equilibrium of the model at a fixed total number of excitons and photons. we find a phase in which both the cavity field and the excitonic polarization are coherent. this phase corresponds to a bose condensate of cavity polaritons, generalized to allow for the fermionic internal structure of the excitons. it is separated from the normal state by an unusual reentrant phase boundary. we calculate the excitation energies of the model, and hence the optical absorption spectra of the cavity. in the condensed phase the absorption spectrum is gapped. the presence of a gap distinguishes the polariton condensate from the normal state and from a conventional laser, even when the inhomogeneous linewidth is so large that there is no observable polariton splitting in the normal state. | arxiv:cond-mat/0102009 |
mean and diam - mean equicontinuity are dynamical properties that have been of use in the study of non - periodic order. we show that the pacman automaton is not almost diam - mean equicontinuous ( it is already known that it is almost mean equicontinuous ). | arxiv:2106.10301 |
canfieldite, ag $ _ 8 $ sns $ _ 6 $, is a semiconducting mineral notable for its high ionic conductivity, photosensitivity, and low thermal conductivity. we report the solution growth of large single crystals of ag $ _ 8 $ sns $ _ 6 $ of mass up to 1 g from a ternary ag - sn - s melt. on cooling from high temperature, ag $ _ 8 $ sns $ _ 6 $ undergoes a known cubic ( f - 43m ) to orthorhombic ( pna2 $ _ 1 $ ) phase transition at $ \ approx $ 460 k. by studying the magnetization and thermal expansion between 5 - 300 k, we discover a second structural transition at $ \ approx $ 120 k. single crystal x - ray diffraction reveals the low temperature phase adopts a different orthorhombic structure with space group pmn2 $ _ 1 $ ( a = 7. 6629 ( 5 ) \ aa, b = 7. 5396 ( 5 ) \ aa, c = 10. 6300 ( 5 ) \ aa, z = 2 at 90 k ) that is isostructural to the room temperature forms of the related se - based compounds ag $ _ 8 $ snse $ _ 6 $ and ag $ _ 8 $ gese $ _ 6 $. the 120 k transition is first - order and has a large thermal hysteresis. based on magnetization and thermal expansion data, the room temperature polymorph can be kinetically arrested into a metastable state by rapidly cooling to temperatures below 40 k. we lastly compare the room and low temperature forms of ag $ _ 8 $ sns $ _ 6 $ with its argyrodite analogues, ag $ _ 8 $ tq $ _ 6 $ ( t = si, ge, sn ; q = s, se ), and identify a trend relating the preferred structures to the unit cell volume, suggesting smaller phase volume favors the pna2 $ _ 1 $ arrangement. we support this picture by showing that the transition to the pmn2 $ _ 1 $ phase is avoided in ge alloyed ag $ _ 8 $ sn $ _ { 1 - x } $ ge $ _ x $ s $ _ 6 $ samples as well as pure ag $ _ 8 $ ges $ _ 6 $. | arxiv:2110.07508 |
magnetic bit writing by short - wave magnons without conversion to the electrical domain is expected to be a game - changer for in - memory computing architectures. recently, the reversal of nanomagnets by propagating magnons was demonstrated. however, experiments have not yet explored different wavelengths and the nonlinear excitation regime of magnons required for computational tasks. we report on the magnetization reversal of individual 20 - nm - thick ni81fe19 ( py ) nanostripes integrated onto 113 - nm - thick yttrium iron garnet ( yig ). we suppress direct interlayer exchange coupling by an intermediate layer such as cu and sio2. exciting magnons in yig with wavelengths { \ lambda } down to 148 nm we observe the reversal of the integrated ferromagnets in a small opposing field of 14 mt. magnons with a small wavelength of { \ lambda } = 195 nm, i. e., twice the width of the py nanostripes, induced the reversal at an unprecedentedly small spin precessional power of about 1 nw after propagating over 15 { \ mu } m in yig. considerations based on dynamic dipolar coupling explain the observed wavelength dependence of magnon - induced reversal efficiency. for an increased power the stripes reversed in an opposing field of only about 1 mt. our findings are important for the practical implementation of nonvolatile storage of broadband magnon signals in yig by means of bistable nanomagnets without the need of an appreciable global magnetic field. | arxiv:2312.15107 |
to address privacy concerns and reduce network latency, there has been a recent trend of compressing cumbersome recommendation models trained on the cloud and deploying compact recommender models to resource - limited devices for the real - time recommendation. existing solutions generally overlook device heterogeneity and user heterogeneity. they require devices with the same budget to share the same model and assume the available device resources ( e. g., memory ) are constant, which is not reflective of reality. considering device and user heterogeneities as well as dynamic resource constraints, this paper proposes a personalized elastic embedding learning framework ( peel ) for the on - device recommendation, which generates personalized elastic embeddings ( pees ) for devices with various memory budgets in a once - for - all manner, adapting to new or dynamic budgets, and addressing user preference diversity by assigning personalized embeddings for different groups of users. specifically, it pretrains a global embedding table with collected user - item interaction instances and clusters users into groups. then, it refines the embedding tables with local interaction instances within each group. pees are generated from the group - wise embedding blocks and their weights that indicate the contribution of each embedding block to the local recommendation performance. given a memory budget, peel efficiently generates pees by selecting embedding blocks with the largest weights, making it adaptable to dynamic memory budgets on devices. furthermore, a diversity - driven regularizer is implemented to encourage the expressiveness of embedding blocks, and a controller is utilized to optimize the weights. extensive experiments are conducted on two public datasets, and the results show that peel yields superior performance on devices with heterogeneous and dynamic memory budgets. | arxiv:2306.10532 |
the trans - neptunian region of the solar system exhibits an intricate dynamical structure, much of which can be explained by an instability - driven orbital history of the giant planets. however, the origins of a highly inclined, and in certain cases retrograde, population of trans - neptunian objects remain elusive within the framework of this evolutionary picture. in this work, we show that the existence of a distant, neptune - like planet that resides on an eccentric and mildly inclined orbit fully accounts for the anomalous component the trans - neptunian orbital distribution. adopting the same parameters for planet nine as those previously invoked to explain the clustering of distant kuiper belt orbits in physical space, we carry out a series of numerical experiments which elucidate the physical process though which highly inclined kuiper belt objects with semi - major axes smaller than 100 au are generated. the identified dynamical pathway demonstrates that enigmatic members of the kuiper belt such as drac and niku are derived from the extended scattered disk of the solar system. | arxiv:1610.04992 |
a semi - empirical ir / vis line list, solis, for the sulphur monoxide molecule $ ^ { 32 } $ s $ ^ { 16 } $ o is presented. solis includes accurate empirical rovibrational energy levels, uncertainties, lifetimes, quantum number assignments, and transition probabilities in the form of einstein $ a $ coefficients covering the $ x \, { } ^ { 3 } \ sigma ^ { - } $, $ a \, { } ^ { 1 } \ delta ^ { } $, $ b \, { } ^ { 1 } \ sigma ^ { + } $, $ a \, { } ^ { 3 } \ pi $, $ b \, { } ^ { 3 } \ sigma ^ { - } $, $ x \, { } ^ { \ prime \ prime3 } \ sigma ^ { + } $, $ a \, { } ^ { \ prime 3 } \ delta $ and $ e \, { } ^ { 1 } \ pi $ systems and wavenumber range up to 43303. 5 cm $ ^ { - 1 } $ ( $ \ geq 230. 93 $ nm ) with $ j \ le 69 $. solis has been computed by solving the rovibronic schr \ " { o } dinger equation for diatomics using the general purpose variational code duo and starting from a published ab initio spectroscopic model of so ( including potential energy curves, coupling curves, ( transition ) dipole moment curves ) which is refined to experimental data. to this end, a database of 50106 experimental transitions, 48972 being non - redundant, has been compiled through the analysis of 29 experimental sources, and a self - consistent network of 8558 rovibronic energy levels for the $ x $, $ a $, $ b $, $ a $, $ b $, and $ c $ electronic states has been generated with the marvel algorithm covering rotational and vibrational quantum numbers $ j \ leq 69 $ and $ v \ leq 30 $ and energies up to 52350. 40 cm $ ^ { - 1 } $. no observed transitions connect to the $ b \, { } ^ { 3 } \ sigma ^ { - } ( v = 0 ) $ state which is required to model perturbations correctly, so we leave fitting the $ b \, { } ^ 3 \ sigma ^ - $ and $ c \, | arxiv:2312.09732 |
we show that the group of holomorphic automorphisms of a stein manifold x of dimension greater than 1 is infinite - dimensional, provided x is a homogeneous space of a holomorphic action of a complex lie group. | arxiv:0806.0693 |
we derived the absolute proper motion ( pm ) of the old, solar - metallicity galactic open cluster m67 using observations collected with cfht ( 1997 ) and with lbt ( 2007 ). about 50 galaxies with relatively sharp nuclei allow us to determine the absolute pm of the cluster. we find ( mu _ alpha cos ( delta ), mu _ delta ) _ j2000. 0 = ( - 9. 6 + / - 1. 1, - 3. 7 + / - 0. 8 ) mas / yr. by adopting a line - of - sight velocity of 33. 8 + / - 0. 2 km / s, and assuming a distance of 815 + / - 50 pc, we explore the influence of the galactic potential, with and without the bar and / or spiral arms, on the galactic orbit of the cluster. | arxiv:1005.0840 |
federated learning ( fl ) endeavors to harness decentralized data while preserving privacy, facing challenges of performance, scalability, and collaboration. asynchronous federated learning ( afl ) methods have emerged as promising alternatives to their synchronous counterparts bounded by the slowest agent, yet they add additional challenges in convergence guarantees, fairness with respect to compute heterogeneity, and incorporation of staleness in aggregated updates. specifically, afl biases model training heavily towards agents who can produce updates faster, leaving slower agents behind, who often also have differently distributed data which is not learned by the global model. naively upweighting introduces incentive issues, where true fast updating agents may falsely report updates at a slower speed to increase their contribution to model training. we introduce fedstaleweight, an algorithm addressing fairness in aggregating asynchronous client updates by employing average staleness to compute fair re - weightings. fedstaleweight reframes asynchronous federated learning aggregation as a mechanism design problem, devising a weighting strategy that incentivizes truthful compute speed reporting without favoring faster update - producing agents by upweighting agent updates based on staleness. leveraging only observed agent update staleness, fedstaleweight results in more equitable aggregation on a per - agent basis. we both provide theoretical convergence guarantees in the smooth, non - convex setting and empirically compare fedstaleweight against the commonly used asynchronous fedbuff with gradient averaging, demonstrating how it achieves stronger fairness, expediting convergence to a higher global model accuracy. finally, we provide an open - source test bench to facilitate exploration of buffered afl aggregation strategies, fostering further research in asynchronous federated learning paradigms. | arxiv:2406.02877 |
let $ f $ be a morse function on a smooth compact surface $ m $ and $ \ mathcal { s } ' ( f ) $ be a group of $ f $ - preserving diffeomorphisms of $ m $ which are isotopic to the identity map. let also $ g ( f ) $ be a group of automorphisms of the graph of $ f $ induced by elements from $ \ mathcal { s } ' ( f ) $, and $ \ delta ' $ be a subgroup of $ \ mathcal { s } ' ( f ) $ of diffeomorphisms which trivially act on the graph of $ f $ and are isotopic to the identity map. the group $ \ pi _ 0 \ mathcal { s } ' ( f ) $ can be viewed as an analogue of a mapping class group for $ f $ - preserved diffeomorphisms of $ m $. groups $ \ pi _ 0 \ delta ' ( f ) $ and $ g ( f ) $ can be viewed as groups which encode ` combinatorially trivial ' and ` combinatorially nontrivial ' counterparts of $ \ pi _ 0 \ mathcal { s } ' ( f ) $ respectively. in the paper we compute groups $ \ pi _ 0 \ mathcal { s } ' ( f ) $, $ g ( f ) $, and $ \ pi _ 0 \ delta ' ( f ) $ for morse functions on $ 2 $ - torus $ t ^ 2 $. | arxiv:1903.01753 |
a precise measure of the mid - infrared interstellar extinction law is crucial to the investigation of the properties of interstellar dust, especially of the grains in the large size end. based on the stellar parameters derived from the sdss - iii / apogee spectroscopic survey, we select a large sample of g - and k - type giants as the tracers of the galactic mid - infrared extinction. we calculate the intrinsic stellar color excesses from the stellar effective temperatures and use them to determine the mid - infrared extinction for a given line of sight. for the entire sky of the milky way surveyed by apogee, we derive the extinction ( relative to the k $ _ { \ rm s } $ band at wavelength $ \ lambda = 2. 16 \ mu $ m ) for the four wise bands at 3. 4, 4. 6, 12 and 22 $ \ mu $ m, the four spitzer / irac bands at 3. 6, 4. 5, 5. 8 and 8 $ \ mu $ m, the spitzer / mips24 band at 23. 7 $ \ mu $ m and for the first time, the akari / s9w band at 8. 23 $ \ mu $ m. our results agree with previous works in that the extinction curve is flat in the ~ 3 - - 8 $ \ mu $ m wavelength range and is generally consistent with the $ r _ v = 5. 5 $ model curve except our determination exceeds the model prediction in the wise / w4 band. although some previous works found that the mid - ir extinction law appears to vary with the extinction depth $ a _ { \ rm { k _ s } } $, no noticeable variation has been found in this work. the uncertainties are analyzed in terms of the bootstrap resampling method and monte - carlo simulation and are found to be rather small. | arxiv:1602.02928 |
we describe the collective hydrodynamic motion of an incommensurate charge density wave state in a clean electronic system. our description simultaneously incorporates the effects of both pinning due to weak disorder and also phase relaxation due to proliferating dislocations. we show that the interplay between these two phenomena has important consequences for charge and momentum transport. for instance, it can lead to metal - insulator transitions. we furthermore identify signatures of fluctuating density waves in frequency and spatially resolved conductivities. phase disordering is well known to lead to a large viscosity. we derive a precise formula for the phase relaxation rate in terms of the viscosity in the dislocation cores. we thereby determine the viscosity of the superconducting state of bscco from the observed melting dynamics of abrikosov lattices and show that the result is consistent with dissipation into bogoliubov quasiparticles. | arxiv:1702.05104 |
we study the problem of online learning in competitive settings in the context of two - sided matching markets. in particular, one side of the market, the agents, must learn about their preferences over the other side, the firms, through repeated interaction while competing with other agents for successful matches. we propose a class of decentralized, communication - and coordination - free algorithms that agents can use to reach to their stable match in structured matching markets. in contrast to prior works, the proposed algorithms make decisions based solely on an agent ' s own history of play and requires no foreknowledge of the firms ' preferences. our algorithms are constructed by splitting up the statistical problem of learning one ' s preferences, from noisy observations, from the problem of competing for firms. we show that under realistic structural assumptions on the underlying preferences of the agents and firms, the proposed algorithms incur a regret which grows at most logarithmically in the time horizon. our results show that, in the case of matching markets, competition need not drastically affect the performance of decentralized, communication and coordination free online learning algorithms. | arxiv:2206.02344 |
the magnetic structure and phase diagram of the layered ferromagnetic compound fe $ _ 3 $ gete $ _ 2 $ has been investigated by a combination of synthesis, x - ray and neutron diffraction, high resolution microscopy, and magnetization measurements. single crystals were synthesized by self - flux reactions, and single crystal neutron diffraction finds ferromagnetic order with moments of 1. 11 ( 5 ) $ \ mu _ b $ / fe aligned along the $ c $ - axis at 4k. these flux - grown crystals have a lower curie temperature $ t _ { \ textrm { c } } \ approx $ 150k compared to crystals previously grown by vapor transport ( $ t _ { \ textrm { c } } $ = 220k ). the difference is a reduced fe content in the flux grown crystals, as illustrated by the behavior observed in a series of polycrystalline samples. as fe - content decreases, so does the curie temperature, magnetic anisotropy, and net magnetization. in addition, hall effect and thermoelectric measurements on flux - grown crystals suggest multiple carrier types contribute to electrical transport in fe $ _ { 3 - x } $ gete $ _ 2 $ and structurally - similar ni $ _ { 3 - x } $ gete $ _ 2 $. | arxiv:1508.06959 |
in this paper a technique is given to recover the classical order of the method when explicit exponential runge - kutta methods integrate reaction - diffusion problems. although methods of high stiff order for problems with vanishing boundary conditions can be constructed, that may imply increasing the number of stages and therefore, the computational cost seems bigger than the technique which is suggested here, which just adds some terms with information on the boundaries. moreover, time - dependent boundary conditions are directly tackled here. | arxiv:2211.11318 |
reliable and well - characterized quantum resources are indispensable ingredients in quantum information processing. typically, in a realistic characterization of these resources, apparatuses come with intrinsic uncertainties that can manifest themselves in the form of systematic errors. while systematic errors are generally accounted for through careful calibration, the effect of remaining imperfections on the characterization of quantum resources has been largely overlooked in the literature. in this paper, we investigate the effect of systematic errors that arise from imperfect alignment of measurement bases - - - an error that can conceivably take place due to the limited controlability of measurement devices. we show that characterization of quantum resources using quantum state tomography or entanglement witnesses can be undermined with an amount of such imprecision that is not uncommon in laboratories. curiously, for quantum state tomography, we find that having entanglement can help to reduce the susceptibility to this kind of error. we also briefly discuss how a given entanglement witness can be modified to incorporate the effect of such errors. | arxiv:1203.0911 |
modeling solute segregation to grain boundaries at near first - principles accuracy is a daunting task, particularly at finite concentrations and temperatures that require accurate assessments of solute - solute interactions and excess vibrational entropy of segregation that are computationally intensive. here, we apply a generalized machine learning potential for 16 elements, including ag, al, au, cr, cu, mg, mo, ni, pb, pd, pt, ta, ti, v, w and zr, to provide a self - consistent spectral database for all of these energetic components in of 240 binary alloy polycrystals. the segregation spectra of al - based alloys are validated against past quantum - accurate simulations and show improved predictive ability with some existing atom probe tomography experimental data. | arxiv:2502.08017 |
in this paper we derive semi - empirical cepheid period - luminosity ( p - l ) relations in the sloan ugriz magnitudes by combining the observed bvi mean magnitudes from the large magellanic cloud cepheids ( lmc ) and theoretical bolometric corrections. we also constructed empirical gr band p - l relations, using the publicly available johnson - sloan photometric transformations, to be compared with our semi - empirical p - l relations. these two sets of p - l relations are consistent with each other. | arxiv:0706.1537 |
we study the limit in low intensity of poisson - - voronoi tessellations in hyperbolic spaces $ \ mathbb { h } _ { d } $ for $ d \ geq 2 $. in contrast to the euclidean setting, a limiting nontrivial ideal tessellation $ \ mathcal { v } _ { d } $ appears as the intensity tends to $ 0 $. the tessellation $ \ mathcal { v } _ { d } $ is a natural, isometry - invariant decomposition of $ \ mathbb { h } _ { d } $ into countably many unbounded polytopes, each with a unique end. we study its basic properties, in particular, the geometric features of its cells. | arxiv:2303.16831 |
the development of mobile cloud computing has brought many benefits to mobile users as well as cloud service providers. however, mobile cloud computing is facing some challenges, especially security - related problems due to the growing number of cyberattacks which can cause serious losses. in this paper, we propose a dynamic framework together with advanced risk management strategies to minimize losses caused by cyberattacks to a cloud service provider. in particular, this framework allows the cloud service provider to select appropriate security solutions, e. g., security software / hardware implementation and insurance policies, to deal with different types of attacks. furthermore, the stochastic programming approach is adopted to minimize the expected total loss for the cloud service provider under its financial capability and uncertainty of attacks and their potential losses. through numerical evaluation, we show that our approach is an effective tool in not only dealing with cyberattacks under uncertainty, but also minimizing the total loss for the cloud service provider given its available budget. | arxiv:1712.05913 |
\ mbox { { be } } } ( \ gamma ) $ is attained. moreover, we remark that there is a region $ \ gamma _ 0 \ leq \ gamma < \ gamma _ c ^ { \ star }, $ where the third eigenspace of the linearized operator contains only spherical harmonics of degree $ 1. $ our result improves some of the results in wei - wu [ arxiv : 2308. 04667 ] corresponding to the hs inequality. | arxiv:2505.07039 |
while it is known that third family hypercharge models can explain the neutral current $ b - $ anomalies, it was hitherto unclear whether the $ z - z ^ \ prime $ mixing predicted by such models could simultaneously fit electroweak precision observables. here, we perform global fits of several third family hypercharge models to a combination of electroweak data and those data pertinent to the neutral current $ b - $ anomalies. while the standard model is in tension with this combined data set with a $ p - $ value of $. 00068 $, simple versions of the models ( fitting two additional parameters each ) provide much improved fits. the original third family hypercharge model, for example, has a $ p - $ value of $. 065 $, i. e. $ \ sqrt { \ delta \ chi ^ 2 } = 6. 5 \ sigma $. | arxiv:2103.12056 |
we report on a project undertaken in summer 2017 by pre - university student interns at haus der astronomie : point - particle simulations of galaxy collisions with the aim of reproducing observational data from such collisions. we succeeded in providing a visually similar representation of both ngc 5426 / 7 and the " antennae " galaxies ( ngc 4038 / 9 ), and were able to make deductions about the relative positions and orbits of these galaxies. the project is an example for how participants with little more than high - school level previous knowledge can successfully tackle, and understand, advanced topics from current astrophysical research. this report was written by the two participants ( m. b. - c. and m. t. ), on whose experiences it is based, in collaboration with their supervisor at haus der astronomie ( m. p. ). | arxiv:1812.00779 |
the most precise value of v _ { ud }, which is obtained from superallowed nuclear beta decay, leads to a violation of ckm unitarity by 2. 2 sigma. experiments are underway on two continents to test and improve this result through decay studies of odd - odd n = z nuclei with a > or = 62. we show, in a series of illustrative shell - model calculations, that numerous weak gamow - teller branches are expected to compete with the superallowed branch in each of these nuclei. though the total gamow - teller strength is significant, many of the individual branches will be unobservably weak. thus, new techniques must be developed if reliable ft - values are to be obtained with 0. 1 % precision for the superallowed branches. | arxiv:nucl-th/0308005 |
a classical result of time - frequency analysis, obtained by i. daubechies in 1988, states that the eigenfunctions of a time - frequency localization operator with circular localization domain and gaussian analysis window are the hermite functions. in this contribution, a converse of daubechies ' theorem is proved. more precisely, it is shown that, for simply connected localization domains, if one of the eigenfunctions of a time - frequency localization operator with gaussian window is a hermite function, then its localization domain is a disc. the general problem of obtaining, from some knowledge of its eigenfunctions, information about the symbol of a time - frequency localization operator, is denoted as the inverse problem, and the problem studied by daubechies as the direct problem of time - frequency analysis. here, we also solve the corresponding problem for wavelet localization, providing the inverse problem analogue of the direct problem studied by daubechies and paul. | arxiv:1202.5841 |
direct - ink writing leverages the rheological complexity of yield - stress fluids to construct complex geometries, particularly those with large gaps across internal structures. however, extensional rheological properties have rarely been considered in work that studies rheology - printability correlations. here, we test our hypothesis that extensional properties correlate with drawability, a key indicator of printability that signifies speed robustness, printing resolution, and gap - spanning performance. we formulated cementitious suspensions using hydroxyapatite ( hap ) particles, independently tuning them for yield stress and extensibility, two crucial rheological properties, and test - printed. to enhance extensibility, we incorporated hydroxypropyl methylcellulose as a polymeric modifier, but this enhancement may decrease as yield stress increases, presenting a challenge in materials design. we modulated particle interactions to achieve a wide range of yield stress and extensibility, allowing for rigorous testing of our hypothesis. this approach created inks with high extensibility and high yield stress, generally considered mutually exclusive properties. we evaluated correlations between drawability and key rheological properties, finding the strongest positive correlation with extensional failure strains ( strain - to - break ) rather than yield stress. we establish a bijective property - manufacturing relationship ( one - on - one mapping of shear yield stress to buildability and extensional strain - to - break to drawability ) by combining our findings on drawability with previous studies on buildability. this relationship provides a comprehensive framework for designing high - performance inks that can be self - supporting, capable of high - speed printing, and allow gap - spanning features. | arxiv:2501.12630 |
in this paper, nash equilibrium seeking among a network of players is considered. different from many existing works on nash equilibrium seeking in non - cooperative games, the players considered in this paper cannot directly observe the actions of the players who are not their neighbors. instead, the players are supposed to be capable of communicating with each other via an undirected and connected communication graph. by a synthesis of a leader - following consensus protocol and the gradient play, a distributed nash equilibrium seeking strategy is proposed for the non - cooperative games. analytical analysis on the convergence of the players ' actions to the nash equilibrium is conducted via lyapunov stability analysis. for games with non - quadratic payoffs, where multiple isolated nash equilibria may coexist in the game, a local convergence result is derived under certain conditions. then, a stronger condition is provided to derive a non - local convergence result for the non - quadratic games. for quadratic games, it is shown that the proposed seeking strategy enables the players ' actions to converge to the nash equilibrium globally under the given conditions. numerical examples are provided to verify the effectiveness of the proposed seeking strategy. | arxiv:1602.00771 |
document shadow removal is an integral task in document enhancement pipelines, as it improves visibility, readability and thus the overall quality. assuming that the majority of practical document shadow removal scenarios require real - time, accurate models that can produce high - resolution outputs in - the - wild, we propose laplacian pyramid with input / output attention network ( lp - ioanet ), a novel pipeline with a lightweight architecture and an upsampling module. furthermore, we propose three new datasets which cover a wide range of lighting conditions, images, shadow shapes and viewpoints. our results show that we outperform the state - of - the - art by a 35 % relative improvement in mean average error ( mae ), while running real - time in four times the resolution ( of the state - of - the - art method ) on a mobile device. | arxiv:2303.12862 |
despite their strong performance on many tasks, pre - trained language models have been shown to struggle on out - of - distribution compositional generalization. meanwhile, recent work has shown considerable improvements on many nlp tasks from model scaling. can scaling up model size also improve compositional generalization in semantic parsing? we evaluate encoder - decoder models up to 11b parameters and decoder - only models up to 540b parameters, and compare model scaling curves for three different methods for applying a pre - trained language model to a new task : fine - tuning all parameters, prompt tuning, and in - context learning. we observe that fine - tuning generally has flat or negative scaling curves on out - of - distribution compositional generalization in semantic parsing evaluations. in - context learning has positive scaling curves, but is generally outperformed by much smaller fine - tuned models. prompt - tuning can outperform fine - tuning, suggesting further potential improvements from scaling as it exhibits a more positive scaling curve. additionally, we identify several error trends that vary with model scale. for example, larger models are generally better at modeling the syntax of the output space, but are also more prone to certain types of overfitting. overall, our study highlights limitations of current techniques for effectively leveraging model scale for compositional generalization, while our analysis also suggests promising directions for future work. | arxiv:2205.12253 |
this is a concise introduction to the theory of lie groupoids, with emphasis in their role as models for stacks. after some preliminaries, we review the foundations on lie groupoids, and we carefully study equivalences and proper groupoids. differentiable stacks are geometric objects which have manifolds and orbifolds as special instances, and can be presented as the transverse geometry of a lie groupoid. two lie groupoids are equivalent if they are presenting the same stack, and proper groupoids are presentations of separated stacks, which by the linearization theorem are locally modeled by linear actions of compact groups. we discuss all these notions in detail. our treatment diverges from the expositions already in the literature, looking for a complementary insight over this rich theory that is still in development. | arxiv:1212.6714 |
the study of stability of gravitational perturbations in higher derivative gravity has shown that at the linear level the massive unphysical ghost is not generated from vacuum if the initial seed of metric perturbation has frequency essentially below the planck threshold. the mathematical knowledge indicated that the linear stability is supposed to hold even at the nonperturbative level, but in such a complicated case it is important to perform a verification of this statement. we compare the asymptotic stability solutions at the linear and full nonperturbative levels for the bianchi - i metric with small anisotropies, which can be regarded as an extreme, zero frequency limit of a gravitational wave. as one should expect from the combination of previous analysis and general mathematical theorems, there is a good correspondence between linear stability and the nonperturbative asymptotic behavior. | arxiv:1903.01044 |
in this paper, we present a deep learning algorithm to rapidly obtain high quality ct reconstructions for am parts. in particular, we propose to use cad models of the parts that are to be manufactured, introduce typical defects and simulate xct measurements. these simulated measurements were processed using fbp ( computationally simple but result in noisy images ) and the mbir technique. we then train a 2. 5d deep convolutional neural network [ 4 ], deemed 2. 5d deep learning mbir ( 2. 5d dl - mbir ), on these pairs of noisy and high - quality 3d volumes to learn a fast, non - linear mapping function. the 2. 5d dl - mbir reconstructs a 3d volume in a 2. 5d scheme where each slice is reconstructed from multiple inputs slices of the fbp input. given this trained system, we can take a small set of measurements on an actual part, process it using a combination of fbp followed by 2. 5d dl - mbir. both steps can be rapidly performed using gpus, resulting in a real - time algorithm that achieves the high - quality of mbir as fast as standard techniques. intuitively, since cad models are typically available for parts to be manufactured, this provides a strong constraint " prior " which can be leveraged to improve the reconstruction. | arxiv:1904.12585 |
we introduce a meta - learning algorithm for adversarially robust classification. the proposed method tries to be as model agnostic as possible and optimizes a dataset prior to its deployment in a machine learning system, aiming to effectively erase its non - robust features. once the dataset has been created, in principle no specialized algorithm ( besides standard gradient descent ) is needed to train a robust model. we formulate the data optimization procedure as a bi - level optimization problem on kernel regression, with a class of kernels that describe infinitely wide neural nets ( neural tangent kernels ). we present extensive experiments on standard computer vision benchmarks using a variety of different models, demonstrating the effectiveness of our method, while also pointing out its current shortcomings. in parallel, we revisit prior work that also focused on the problem of data optimization for robust classification \ citep { ily + 19 }, and show that being robust to adversarial attacks after standard ( gradient descent ) training on a suitable dataset is more challenging than previously thought. | arxiv:2207.11727 |
in this paper, we investigate the green measure for a class of non - gaussian processes in $ \ mathbb { r } ^ { d } $. these measures are associated with the family of generalized grey brownian motions $ b _ { \ beta, \ alpha } $, $ 0 < \ beta \ le1 $, $ 0 < \ alpha \ le2 $. this family includes both fractional brownian motion, brownian motion, and other non - gaussian processes. we show that the perpetual integral exists with probability $ 1 $ for $ d \ alpha > 2 $ and $ 1 < \ alpha \ le2 $. the green measure then generalizes those measures of all these classes. | arxiv:2404.02076 |
in this paper, we apply the hierarchical strategy to a semilinear weakly degenerate parabolic equation involving a gradient term. we use the stackelberg - nash strategy with one leader which tries to drive the solution to zero and two followers intended to solve a nash equilibrium corresponding to a bi - objective optimal control problem. since the system is semilinear, the functionals are not convex in general. to overcome this difficulty, we first prove the existence and uniqueness of the nash quasi - equilibrium, which is a weaker formulation of the nash equilibrium. next, with additional conditions, we establish the equivalence between the nash quasi - equilibrium and the nash equilibrium. we establish a suitable carleman inequality for the adjoint system and then an observability inequality. based on this observability inequality, we prove the null controllability of the linearized system. then, due to the kakutani ' s fixed point theorem, we obtain the null controllability of the main system. | arxiv:2209.12450 |
a value - at - risk based model is proposed to compute the adequate equity capital necessary to cover potential losses due to operational risks, such as human and system process failures, in banking organizations. exploring the analogy to a lattice gas model from physics, correlations between sequential failures are modeled by as functionally defined, heterogeneous couplings between mutually supportive processes. in contrast to traditional risk models for market and credit risk, where correlations are described by the covariance of gaussian processes, the dynamics of the model shows collective phenomena such as bursts and avalanches of process failures. | arxiv:cond-mat/0204368 |
the emerging internet of things ( iot ) - driven ultra - dense small cell networks ( ud - scns ) will need to combat a variety of challenges. on one hand, massive number of devices sharing the limited wireless resources will render centralized control mechanisms infeasible due to the excessive cost of information acquisition and computations. on the other hand, to reduce energy consumption from fixed power grid and / or battery, many iot devices may need to depend on the energy harvested from the ambient environment ( e. g., from rf transmissions, environmental sources ). however, due to the opportunistic nature of energy harvesting, this will introduce uncertainty in the network operation. in this article, we study the distributed cell association problem for energy harvesting iot devices in ud - scns. after reviewing the state - of - the - art research on the cell association problem in small cell networks, we outline the major challenges for distributed cell association in iot - driven ud - scns where the iot devices will need to perform cell association in a distributed manner in presence of uncertainty ( e. g., limited knowledge on channel / network ) and limited computational capabilities. to this end, we propose an approach based on mean - field multi - armed bandit games to solve the uplink cell association problem for energy harvesting iot devices in a ud - scn. this approach is particularly suitable to analyze large multi - agent systems under uncertainty and lack of information. we provide some theoretical results as well as preliminary performance evaluation results for the proposed approach. | arxiv:1605.00057 |
we describe a formalism underlying the renormalization procedure and batalin - vilkoviski formalism. in the framework of this formalism, we give a mathematical definition of ope - algebra and describe an additional natural structure which produces a * - lie algebra structure on the ( cohomologically shifted ) d - module of observables, whence an $ l _ \ infty $ algebra structure on the space of global sections of the de rham complex of this d - module. given a maurer - cartan element in this $ l _ \ infty $ algebra, we construct a deformation of the ope - algebra, which is exactly the desired renormalization. | arxiv:math/0312219 |
peculiarities of the turbulent two phase and multiphase flows of the mutually immiscible liquids and averaged differential equations for their modeling are considered based on the approach, which was first developed and proposed by prof. a. i. nakorchevski as an alternative to a number of the well known averaged multiphase dynamics equations. the main difference of the new method was in an averaging of the navier stokes equations by phases and components in time instead of the widely spread spatial averaging in multiphase mechanics. what was more, introduction of the so called function indicator of the phases in a flow allowed recognizing the phases in their movement in a multiphase mixture, both theoretically and experimentally. for experimental study the special micro sensor was invented and created, which was successfully applied. in this paper, the method of nakorchevski is described in application to some multiphase tasks, and a discussion is presented as concern to advantages of the method for study of turbulent two phase flows of water oil immiscible mixture, as well as many other similar mixtures, where it is important to know the peculiarities of the phases movement and their mixing in a multiphase flow. | arxiv:1802.08846 |
this paper deals with asymptotic expressions of the mean time to failure ( mttf ) and higher moments for large, recursive, and non - repairable systems in the context of two - terminal reliability. our aim is to extend the well - known results of the series and parallel cases. we first consider several exactly solvable configurations of identical components with exponential failure - time distribution functions to illustrate different ( logarithmic or power - law ) behaviors as the size of the system, indexed by an integer n, increases. the general case is then addressed : it provides a simple interpretation of the origin of the power - law exponent and an efficient asymptotic expression for the total reliability of large, recursive systems. finally, we assess the influence of the non - exponential character of the component reliability on the n - dependence of the mttf. | arxiv:0807.0626 |
we are in the midst of a transformation of the digital news ecosystem. the expansion of online social networks, the influence of recommender systems, increased automation, and new generative artificial intelligence tools are rapidly changing the speed and the way misinformation about climate change and sustainability issues moves around the world. policymakers, researchers and the public need to combine forces to address the dangerous combination of opaque social media algorithms, polarizing social bots, and a new generation of ai - generated content. this synthesis brief is the result of a collaboration between stockholm resilience centre at stockholm university, the beijer institute of ecological economics at the royal swedish academy of sciences, the complexity science hub vienna, and karolinska institutet. it has been put together as an independent contribution to the nobel prize summit 2023, truth, trust and hope, washington d. c., 24th to 26th of may 2023. | arxiv:2306.12807 |
this paper proposes an information retrieval method for the economy news. the effect of economy news, are researched in the word level and stock market values are considered as the ground proof. the correlation between stock market prices and economy news is an already addressed problem for most of the countries. the most well - known approach is applying the text mining approaches to the news and some time series analysis techniques over stock market closing values in order to apply classification or clustering algorithms over the features extracted. this study goes further and tries to ask the question what are the available time series analysis techniques for the stock market closing values and which one is the most suitable? in this study, the news and their dates are collected into a database and text mining is applied over the news, the text mining part has been kept simple with only term frequency - inverse document frequency method. for the time series analysis part, we have studied 10 different methods such as random walk, moving average, acceleration, bollinger band, price rate of change, periodic average, difference, momentum or relative strength index and their variation. in this study we have also explained these techniques in a comparative way and we have applied the methods over turkish stock market closing values for more than a 2 year period. on the other hand, we have applied the term frequency - inverse document frequency method on the economy news of one of the high - circulating newspapers in turkey. | arxiv:1403.2002 |
we propose a novel learning paradigm, self - imitation via reduction ( sir ), for solving compositional reinforcement learning problems. sir is based on two core ideas : task reduction and self - imitation. task reduction tackles a hard - to - solve task by actively reducing it to an easier task whose solution is known by the rl agent. once the original hard task is successfully solved by task reduction, the agent naturally obtains a self - generated solution trajectory to imitate. by continuously collecting and imitating such demonstrations, the agent is able to progressively expand the solved subspace in the entire task space. experiment results show that sir can significantly accelerate and improve learning on a variety of challenging sparse - reward continuous - control problems with compositional structures. code and videos are available at https : / / sites. google. com / view / sir - compositional. | arxiv:2103.07607 |
we prove that every complete einstein ( riemannian or pseudo - riemannian ) metric $ g $ is geodesically rigid : if any other complete metric $ \ bar g $ has the same ( unparametrized ) geodesics with $ g $, then the levi - civita connections of $ g $ and $ \ bar g $ coincide. | arxiv:0806.3169 |
we present resent results regarding invertible, non - degenerate solutions of the set - theoretic yang - baxter and reflection equations. we recall the notion of braces and we present and prove various fundamental properties required for the solutions of the set theoretic yang - baxter equation. we then restrict our attention on involutive solutions and consider lambda parametric set - theoretic solutions of the yang - baxter equation and we extract the associated quantum algebra. we also discuss the notion of the drinfeld twist for involutive solutions and their relation to the yangian. we next focus on reflections and we derive the associated defining algebra relations for r - matrices being baxterized solutions of the symmetric group. we show that there exists a ` ` reflection ' ' finite sub - algebra for some special choice of reflection maps. | arxiv:2307.06140 |
optical modulators are required to have high modulation bandwidths and a compact footprint. in this paper we experimentally demonstrate a novel si / in $ _ 2 $ o $ _ 3 $ hybrid plasmonic waveguide modulator, which is realized by an asymmetric directional coupler ( adc ) consisting of a silicon photonic waveguide and a si / in $ _ 2 $ o $ _ 3 $ hybrid plasmonic waveguide. the optical signal is modulated by radio - frequency ( rf ) signal applied on the au electrodes at the top of mos capacitor and contacting the in $ _ 2 $ o $ _ 3 $ thin film. the record - high modulation bandwidth of > 40 ghz is realized by a silicon - doping - free metal - oxide - in $ _ 2 $ o $ _ 3 $ capacitor integrated in a 3. 5 - $ \ mu $ m - long asymmetric directional coupler ( adc ) for the first time. | arxiv:2201.06258 |
due to their strict photon - number correlation, the twin beams produced in parametric down - conversion ( pdc ) work well for heralded state generation. often, however, this state manipulation is distorted by the optical losses in the herald and by the higher photon - number contributions inevitable in the pdc process. in order to find feasible figures of merit for characterizing the heralded states, we investigate their normalized factorial moments of the photon number that can be accessed regardless of the optical losses in the detection. we then perform a measurement of the joint photon statistics of twin beams from a semiconductor bragg - reflection waveguide with transition - edge sensors acting as photon - number - resolving detectors. we extract the photon - number parity of heralded single photons in a loss - tolerant fashion by utilizing the moment generating function. the photon - number parity is highly practicable in quantum state characterization, since it takes into account the complete photon - number content of the target state. | arxiv:1906.12191 |
it is logically possible that the trace anomaly in four dimension includes the hirzebruch - pontryagin density in cp violating theories. although the term vanishes at free conformal fixed points, we realize such a possibility in the holographic renormalization group and show that it is indeed possible. the hirzebruch - pontryagin term in the trace anomaly may serve as a barometer to understand how much cp is violated in conformal field theories. | arxiv:1201.3428 |
two level 17 modular functions $ $ r = q ^ { 2 } \ prod _ { n = 1 } ^ { \ infty } ( 1 - q ^ { n } ) ^ { \ left ( \ frac { n } { 17 } \ right ) }, \ quad s = q ^ { 2 } \ prod _ { n = 1 } ^ { \ infty } \ frac { ( 1 - q ^ { 17n } ) ^ { 3 } } { ( 1 - q ^ { n } ) ^ { 3 } }, $ $ are used to construct a new class of ramanujan - sato series for $ 1 / \ pi $. the expansions are induced by modular identities similar to those level of 5 and 13 appearing in ramanujan ' s notebooks. a complete list of rational and quadratic series corresponding to singular values of the parameters is derived. | arxiv:1711.00459 |
a nonlinear viscoelastic theory of nematodynamic type is developed for nematic liquid crystalline ( lc ) semi - flexible polymers. a measure of transient elastic strain due to the change in length of macromolecular strands under stress, and the director of unit length are employed in the theory as hidden variables. in the marked contrast to the common theoretical approaches to low molecular nematics, the effect of directors space gradient is neglected in the present theory. nevertheless, the theory allows describing nonlinear anisotropic viscoelasticity and evolution equation for the director in flows of lc polymers. when lc macromolecules are relatively rigid or when they are soft but the flow is slow, a weakly nonlinear viscoelastic anisotropic behavior is described by few temperature dependent parameters. in the infinitesimal case the evolution equation for director reminds the ericksens equation, but with an additional relaxation term. the present theory can also be applied for analyzing flows of concentrated polymer suspensions and nano - composites filled with uniaxially symmetric particles. | arxiv:cond-mat/0202275 |
this paper presents reports on a series of experiments with a novel dataset evaluating how well large language models ( llms ) can mark ( i. e. grade ) open text responses to short answer questions, specifically, we explore how well different combinations of gpt version and prompt engineering strategies performed at marking real student answers to short answer across different domain areas ( science and history ) and grade - levels ( spanning ages 5 - 16 ) using a new, never - used - before dataset from carousel, a quizzing platform. we found that gpt - 4, with basic few - shot prompting performed well ( kappa, 0. 70 ) and, importantly, very close to human - level performance ( 0. 75 ). this research builds on prior findings that gpt - 4 could reliably score short answer reading comprehension questions at a performance - level very close to that of expert human raters. the proximity to human - level performance, across a variety of subjects and grade levels suggests that llms could be a valuable tool for supporting low - stakes formative assessment tasks in k - 12 education and has important implications for real - world education delivery. | arxiv:2405.02985 |
in this paper, we consider the reflected backward stochastic differential equations driven by g - brownian motion ( reflected g - bsdes ) whose coefficients satisfy the beta - order mao ' s condition. the uniqueness is obtained by some a priori estimates and the existence can be proved by two different methods. the first one is picard iteration and the second one is approximation via penalization. the latter construction is useful to get the comparison theorem. | arxiv:2212.12108 |
we study the btz black holes ( 2 + 1 dimensional space - time ) in the low energy heterotic string theory ( btz - sen bh ). this concept requires us to include a non - trivial dilaton $ \ phi $ and a 3 - form $ h _ { \ mu \ nu \ rho } $ field. by using the hassan - sen transformation and btz black hole as a seed solution, we obtain the solution in the string frame. some properties of the black hole solutions are discussed. | arxiv:2006.12663 |
the collection of distances between pairs of points in a discrete set can provide information about a riemannian manifold. for example, in [ arxiv : 2004. 08621 ] it was shown that if $ m $ is a complete and connected riemannian surface, and the distances between points in some discrete subset of $ m $ correspond to those of a net in $ \ mathbb { r } ^ { 2 } $, then $ m $ is isometric to the euclidean plane. whether the $ n $ - dimensional analog of this theorem holds true is still unknown. in this paper we prove that if $ m $ is a complete and connected $ n $ - dimensional riemannian manifold, and $ x \ subset m $ is a discrete subset such that the distances between points of $ x $ correspond to those of a net in $ \ mathbb { r } ^ { n } $, then $ x $ is a net in $ m $. loosely speaking, this means that there are no mesoscopic portions of the manifold that are oblivious of the embedding. | arxiv:2305.19415 |
understanding the solvation structure of electrolytes is crucial for optimizing the performance and stability of lithium - ion batteries. novel solvents are essential for enhancing electrolyte structure and ensuring better integration with modern electrode systems. however, there are limited studies focused on fluorinated solvent - based electrolytes. herein, we report a new weakly solvated ether electrolyte ( wsee ) composed of a pure fluorinated ether solvent, which results in an anion - rich solvation structure even at a low salt concentration of 1m. to explore this, we selected the advanced fluorinated solvent 2, 2 - difluoroethyl methyl ether ( feme ) and compared it with dipropyl ether ( dpe ), ethylene carbonate ( ec ), and diethyl carbonate ( dec ). the prepared electrolyte systems include dpe with 1m, 1. 8m, and 4m lifsi, feme with 1m, 1. 8m, and 4m lifsi, and a 1 : 1 vol % ec / dec mixture containing 1m lipf6. in this work, we comprehensively investigate the li + solvation structures in these electrolytes using molecular dynamics ( md ) simulations and density functional theory ( dft ) calculations. our computational findings indicate the presence of large ion aggregates ( aggs ) in each dpe - and feme - based electrolyte, while ssips ( 68 % ) are the dominant species in the mixed ec / dec electrolyte. notably, the formation of large ion aggregates is more pronounced in feme - based electrolytes. we find that, similar to dpe, feme solvent also exhibits weak solvating power across all examined salt concentrations. furthermore, the quantum mechanical features of the li + solvation structures in dpe + 1. 8m lifsi, feme + 1. 8m lifsi, and ec / dec + 1m lipf6 electrolytes have been analyzed in detail using dft calculations. we anticipate that this study will provide valuable insights into the li + solvation structures in dpe, feme, and ec / dec electrolytes, where the ether - based electrolytes exhibit closely similar properties. | arxiv:2501.11932 |
chromo - natural inflation is a model where non - abelian gauge fields are sustained by the coupling of the axion with the gauge field through the chern - simons term. while minimal warm inflation is a model where the axion produces a thermal bath of non - abelian gauge particles through the chern - simons term. since both axion inflation models are based on the same action, a natural question is if those are compatible or not. we study axion inflation with the chern - simons term and find that chromo - natural inflation can accommodate radiation with a temperature much larger than the hubble parameter during inflation, which is a characteristic feature of warm inflation. thus, we conclude that chromo - natural warm inflation exists, which must have phenomenologically interesting consequences. | arxiv:2402.08849 |
higher moments of event - by - event net - proton multiplicity distributions are applied to search for the qcd critical point in the heavy ion collisions. it has been demonstrated that higher moments as well as moment products are sensitive to the correlation length and directly connected to the thermodynamic susceptibilities computed in the lattice qcd and hadron resonance gas ( hrg ) model. in this paper, we will present measurements for kurtosis ( $ \ kappa $ ), skewness ( $ s $ ) and variance ( $ \ sigma ^ { 2 } $ ) of net - proton multiplicity distributions at the mid - rapidity ( $ | y | < 0. 5 $ ) and $ 0. 4 < p _ { t } < 0. 8 $ gev / $ c $ for au + au collisions at $ \ sqrt { s _ { nn } } $ = 19. 6, 39, 62. 4, 130 and 200 gev, cu + cu collisions at $ \ sqrt { s _ { nn } } $ = 22. 4, 62. 4 and 200 gev, d + au collisions at $ \ sqrt { s _ { nn } } $ = 200 gev and p + p collisions at $ \ sqrt { s _ { nn } } $ = 62. 4 and 200 gev. the moment products $ \ kappa \ sigma ^ { 2 } $ and $ s \ sigma $ of net - proton distributions, which are related to volume independent baryon number susceptibility ratio, are compared to the lattice qcd and hrg model calculations. the $ \ kappa \ sigma ^ { 2 } $ and $ s \ sigma $ of net - proton distributions are consistent with lattice qcd and hrg model calculations at high energy, which support the thermalization of the colliding system. deviations of $ \ kappa \ sigma ^ { 2 } $ and $ s \ sigma $ for the au + au collisions at low energies from hrg model calculations are also observed. | arxiv:1106.2926 |
building on work of elliott and coworkers, we present three applications of the cuntz semigroup : ( i ) for many simple c $ ^ * $ - algebras, the thomsen semigroup is recovered functorially from the elliott invariant, and this yields a new proof of elliott ' s classification theorem for simple, unital ai algebras ; ( ii ) for the algebras in ( i ), classification of their hilbert modules is similar to the von neumann algebra context ; ( iii ) for the algebras in ( i ), approximate unitary equivalence of self - adjoint operators is characterised in terms of the elliott invariant. | arxiv:0704.3988 |
to develop silicon - based spintronic devices, we have explored high - quality ferromagnetic fe $ _ { 3 } $ si / silicon ( si ) structures. using low - temperature molecular beam epitaxy at 130 $ ^ circ $ c, we realize epitaxial growth of ferromagnetic fe $ _ { 3 } $ si layers on si ( 111 ) with keeping an abrupt interface, and the grown fe $ _ { 3 } $ si layer has the ordered $ do _ { 3 } $ phase. measurements of magnetic and electrical properties for the fe $ _ { 3 } $ si / si ( 111 ) yield a magnetic moment of ~ 3. 16 $ mu _ { b } $ / f. u. at room temperature and a rectifying schottky - diode behavior with the ideality factor of ~ 1. 08, respectively. | arxiv:0810.2835 |
we are using a laser pointer as a light source, and metersticks as an optical branch and the screen for wave optics experiments. it is shown the setup for measurements of wavelength of laser light and rating radial spacing of the cd, diffraction on a wire and a slit, observation of a polarization of light and observation of a hologram. | arxiv:physics/0508210 |
in this article, we give an abstract characterization of the ` ` identity ' ' of an operator space $ v $ by looking at a quantity $ n _ { cb } ( v, u ) $ which is defined in analogue to a well - known quantity in banach space theory. more precisely, we show that there exists a complete isometry from $ v $ to some $ \ mathcal { l } ( h ) $ sending $ u $ to $ { \ rm id } _ h $ if and only if $ n _ { cb } ( v, u ) = 1 $. we will use it to give an abstract characterization of operator systems. moreover, we will show that if $ v $ is a unital operator space and $ w $ is a proper complete $ m $ - ideal, then $ v / w $ is also a unital operator space. as a consequece, the quotient of an operator system by a proper complete $ m $ - ideal is again an operator system. in the appendix, we will also give an abstract characterisation of ` ` non - unital operator systems ' ' using an idea arose from the definition of $ n _ { cb } ( v, u ) $. | arxiv:0805.2447 |
the inner tracking system ( its ) upgrade for the alice experiment at lhc is the first large - area ( $ \ sim $ 10 ~ m $ ^ 2 $ ) silicon vertex detector based on the cmos monolithic active pixel sensor ( maps ) technology, which combines sensitive volume and front - end readout logic in the same piece of silicon. this technology allows a reduced material budget ( target value of 0. 3 \ % on the innermost layers ) thanks to the thin sensors ( 50 - 100 ~ $ \ mu $ m ) and limited need of cooling, in combination with light - material interconnection circuits and support structures. the small pixel pitch ( $ \ sim $ 30 ~ $ \ mu $ m ), the location of the layers ( 7 cylindrical layers with radii ranging from 2. 3 ~ cm to 39. 3 ~ cm from the beam interaction line ), and the limited material budget will provide the alice experiment with extremely precise tracking resolution. the high - rate readout capabilities will also enable alice to collect a large data sample at the 50 ~ khz pb - - pb collision rate expected in the lhc run ~ 3. the new its, now assembled at the surface, is currently undergoing an exhaustive pre - commissioning phase with standalone calibration and cosmic ray data - taking, which will be completed by april 2020 before the installation in the alice detector. experience gained from the construction and the pre - commissioning phase, and plans for the installation and preparation for the data - taking in alice will be presented in this paper. the role played by the new its within the development path of the maps technology for future applications will also be briefly discussed. | arxiv:2001.03042 |
the correlation among the content distributed across a cache - aided broadcast network can be exploited to reduce the delivery load on the shared wireless link. this paper considers a two - user three - file network with correlated content, and studies its fundamental limits for the worst - case demand. a class of achievable schemes based on a two - step source coding approach is proposed. library files are first compressed using gray - wyner source coding, and then cached and delivered using a combination of correlation - unaware cache - aided coded multicast schemes. the second step is interesting in its own right and considers a multiple - request caching problem, whose solution requires coding in the placement phase. a lower bound on the optimal peak rate - memory trade - off is derived, which is used to evaluate the performance of the proposed scheme. it is shown that for symmetric sources the two - step strategy achieves the lower bound for large cache capacities, and it is within half of the joint entropy of two of the sources conditioned on the third source for all other cache sizes. | arxiv:1712.01464 |
we characterize riesz frames and frames with the subframe property and use this to answer most of the questions from the literature concerning these properties and their relationships to the projection methods etc. | arxiv:math/9811149 |
the beam lifetime in an electron storage ring is also limited by the loss rate of the stored electrons due to the elastic coulomb scattering of electrons with the nuclei of residual gas atoms. the contribution to the beam lifetime due to this elastic scattering depends upon the shape factor which is governed by the shape of the vacuum chamber. in this paper, analytical expressions for the shape factor for a rectangular and an elliptical vacuum chamber as a function of longitudinal position along the circumference in a storage ring are derived using an approach in which the position of electrons at the focusing quadrupole is transformed to the location of defocusing quadrupole and vice versa to define the parts of the vacuum chamber, where the loss of electrons takes place at the location of quadrupoles. the expressions available in the literature are for the average shape factors. the expression of shape factor for a rectangular chamber derived in this paper are similar to the expression for average shape factor quoted in the literature, whereas a new expression for elliptical shape of vacuum chamber having no resemblance with the available expression for average shape factor is obtained. a comparative study of shape factors at each scattering location in the ring obtained from derived expressions and with the existing expressions are reported using indus - 2 lattice parameters for rectangular and elliptical shapes of the chamber. a comparison of average shape factors for these two shapes using derived as well as existing expressions is also reported. these studies indicate that the effect of the rectangular and elliptical shape of vacuum chamber on beam lifetime due to elastic coulomb scattering between electrons and nuclei of residual gas molecules is nearly same. | arxiv:1409.3060 |
in recent years, organic - inorganic hybrid perovskites have attracted wide attention due to their excellent optoelectronic properties in the application of optoelectronic devices. in the manufacturing process of perovskite solar cells, perovskite films inevitably have residual stress caused by non - stoichiometry components and the external load. however, their effects on the structural stability and photovoltaic performance of perovskite solar cells are still not clear. in this work, we investigated the effects of external strain on the structural stability and optoelectronic properties of tetragonal mapbi3 by using the first - principles calculations. we found that the migration barrier of i - ion increases in the presence of compressive strain and decreases with tensile strain, indicating that the compressive strain can enhance the structural stability of halide perovskites. in addition, the light absorption and electronic properties of mapbi3 under compressive strain are also improved. the variations of the band gap under triaxial and biaxial strains are consistent within a certain range of strain, resulting from the fact that the band edge positions are mainly influenced by the pb - i bond in the equatorial plane. our results provide useful guidance for realizing the commercial applications of mapbi3 - based perovskite solar cells. | arxiv:2001.01041 |
we give necessary and sufficient conditions for the boundedness of generalized fractional integral and maximal operators on orlicz - morrey and weak orlicz - morrey spaces. to do this we prove the weak - weak type modular inequality of the hardy - littlewood maximal operator with respect to the young function. orlicz - morrey spaces contain $ l ^ p $ spaces ( $ 1 \ le p \ le \ infty $ ), orlicz spaces and generalized morrey spaces as special cases. hence we get necessary and sufficient conditions on these function spaces as corollaries. | arxiv:2107.10553 |
phase transitions in dissipative quantum systems have been investigated using various analytical approaches, particularly in the mean - field ( mf ) limit. however, analytical results often depend on specific methodologies. for instance, keldysh formalism shows that the dissipative transverse ising ( dti ) model exhibits a discontinuous transition at the upper critical dimension, $ d _ c = 3 $, whereas the fluctuationless mf approach predicts a continuous transition in infinite dimensions ( $ d _ \ infty $ ). these two solutions cannot be reconciled because the mf solutions above $ d _ c $ should be identical. this necessitates a numerical verification. however, numerical studies on large systems may not be feasible because of the exponential increase in computational complexity as $ \ mathcal { o } ( 2 ^ { 2n } ) $ with system size $ n $. here, we note that because spins can be regarded as being fully connected at $ d _ \ infty $, the spin indices can be permutation invariant, and the number of quantum states can be considerably contracted with the computational complexity $ \ mathcal { o } ( n ^ 3 ) $. the lindblad equation is transformed into a dynamic equation based on the contracted states. applying the runge - - kutta algorithm to the dynamic equation, we obtain all the critical exponents, including the dynamic exponent $ z \ approx 0. 5 $. moreover, since the dti model has $ \ mathbb { z } _ 2 $ symmetry, the hyperscaling relation has the form $ 2 \ beta + \ gamma = \ nu ( d + z ) $, we obtain the relation $ d _ c + z = 4 $ in the mf limit. hence, $ d _ c \ approx 3. 5 $ ; thus, the discontinuous transition at $ d = 3 $ cannot be treated as an mf solution. we conclude that the permutation invariance at $ d _ \ infty $ can be used effectively to check the validity of an analytic mf solution in quantum phase transitions. | arxiv:2110.09435 |
to further investigate the interplay between ferromagnetism and topological insulators, thin films of the low - carrier topological insulator ( bi $ _ x $ sb $ _ { 1 - x } $ ) $ _ 2 $ te $ _ 3 $ were deposited on the insulating ferromagnet eus ( 100 ) in situ. ac susceptibility indicates magnetic anomalies between $ t \ approx30 ~ \ mathrm { k } $ and $ t \ approx60 ~ \ mathrm { k } $, well above the curie temperature $ t _ c \ approx 15 ~ \ mathrm { k } $ of eus. when the fermi level is close to the dirac point and the surface state dominates the electric conduction, sharp increases in resistance with decreasing temperatures were observed concurrently with the magnetic anomalies. positive - negative magnetoresistance crossovers were observed at the curie temperature, which seem only to appear when the sheet resistance exceeds the mott - ioffe - regel limit $ h / e ^ 2 $. a two - stage gap - opening process due to magnetic proximity is proposed. | arxiv:1804.02061 |
we consider the problem of extinction processes on random networks with a given structure. for sufficiently large well - mixed populations, the process of extinction of one or more state variable components occurs in the tail of the quasi - stationary probability distribution, thereby making it a rare event. here we show how to extend the theory of large deviations to random networks to predict extinction times. in particular, we use the theory to find the most probable path leading to extinction. we apply the methodology to epidemic models and discover how mean extinction times scale with epidemiological and network parameters in erdos - renyi networks. the results are shown to compare quite well with monte carlo simulations of the network in predicting both the most probable paths to extinction and mean extinction times. | arxiv:1411.0017 |
we describe the incorporation of polarized radiative transfer into the atmospheric radiative transfer modelling code vstar ( versatile software for transfer of atmospheric radiation ). using a vector discrete - ordinate radiative transfer code we are able to generate maps of radiance and polarization across the disc of a planet, and integrate over these to get the full - disc polarization. in this way we are able to obtain disc - resolved, phase - resolved and spectrally - resolved intensity and polarization for any of the wide range of atmopsheres that can be modelled with vstar. we have tested the code by reproducing a standard benchmark problem, as well as by comparing with classic calculations of the polarization phase curves of venus. we apply the code to modelling the polarization phase curves of the hot jupiter system hd 189733b. we find that the highest polarization amplitudes are produced with optically thick rayleigh scattering clouds and these would result in a polarization amplitude of 27 ppm for the planetary signal seen in the combined light of the star and planet. a more realistic cloud model consistent with the observed transmission spectrum results is an amplitude of ~ 20 ppm. decreasing the optical depth of the cloud, or making the cloud particles more absorbing, both have the effect of increasing the polarization of the reflected light but reducing the amount of reflected light and hence the observed polarization amplitude. | arxiv:1807.04443 |
we describe the ultraviolet spectra of the ap star alpha ^ 2 cvn that have been acquired with the hubble space telescope and the nature of the optical region analyses for its rotational velocity and elemental abundances that have been undertaken in support of the ultraviolet data. | arxiv:astro-ph/9805210 |
in order to fully exploit the ballistic potential of particle therapy, we propose an online range monitoring concept based on high - resolution time - of - flight ( tof ) - resolved prompt gamma ( pg ) detection in a single proton counting regime. in a proof of principle experiment, different types of monolithic scintillating gamma detectors are read in time coincidence with a diamond - based beam hodoscope, in order to build tof spectra of pg generated in a heterogeneous target presenting an air cavity of variable thickness. since the measurement was carried out at low beam currents ( $ < $ 1 proton / bunch ) it was possible to reach excellent coincidence time resolutions, of the order of 100 ps ( $ \ sigma $ ). our goal is to detect possible deviations of the proton range with respect to treatment planning within a few intense irradiation spots at the beginning of the session and then carry on the treatment at standard beam currents. the measurements were limited to 10 mm proton range shift. a monte carlo simulation study reproducing the experiment has shown that a 3 mm shift can be detected at 2 $ \ sigma $ by a single detector of $ \ sim 1. 4 \ times 10 ^ { - 3 } $ absolute detection efficiency within a single irradiation spot ( $ \ sim $ 10 $ ^ { 8 } $ protons ) and an optimised experimental set - up. | arxiv:2001.01470 |
let $ a $ be the ring of integers of global field $ k $. let $ g \ subseteq gl _ 2 ( a ) $ be a finite group. let $ g $ act linearly on $ r = a [ x, y ] $ ( fixing $ a $ ). let $ r ^ g $ be the ring of invariants. in the equi - characteristic case we prove $ r ^ g $ is cohen - macaulay. in mixed characteristic case we prove that if for all primes $ p $ dividing $ | g | $ the sylow $ p $ - subgroup of $ g $ has exponent $ p $ then $ r ^ g $ is cohen - macaulay. we prove a similar case if for all primes $ p $ dividing $ | g | $ the prime $ p $ is un - ramified in $ k $. | arxiv:2402.08962 |
recently the proof of factorization in heavy quarkonium production in nrqcd color octet mechanism is given at next - to - next - to - leading order ( nnlo ) in coupling constant by using diagrammatic method of qcd. in this paper we prove factorization in heavy quarkonium production in nrqcd color octet mechanism at all order in coupling constant by using path integral method of qcd. our proof is valid to all powers in the heavy quark relative velocity. we find that the gauge invariance and the factorization at all order in coupling constant require gauge - completed non - perturbative nrqcd matrix elements that were introduced previously to prove factorization at nnlo. | arxiv:1506.02593 |
despite the surge of deep learning in the past decade, some users are skeptical to deploy these models in practice due to their black - box nature. specifically, in the medical space where there are severe potential repercussions, we need to develop methods to gain confidence in the models ' decisions. to this end, we propose a novel medical imaging generative adversarial framework, medxgan ( medical explanation gan ), to visually explain what a medical classifier focuses on in its binary predictions. by encoding domain knowledge of medical images, we are able to disentangle anatomical structure and pathology, leading to fine - grained visualization through latent interpolation. furthermore, we optimize the latent space such that interpolation explains how the features contribute to the classifier ' s output. our method outperforms baselines such as gradient - weighted class activation mapping ( grad - cam ) and integrated gradients in localization and explanatory ability. additionally, a combination of the medxgan with integrated gradients can yield explanations more robust to noise. the code is available at : https : / / avdravid. github. io / medxgan _ page /. | arxiv:2204.05376 |
experimental mathematics is an approach to mathematics in which computation is used to investigate mathematical objects and identify properties and patterns. it has been defined as " that branch of mathematics that concerns itself ultimately with the codification and transmission of insights within the mathematical community through the use of experimental ( in either the galilean, baconian, aristotelian or kantian sense ) exploration of conjectures and more informal beliefs and a careful analysis of the data acquired in this pursuit. " as expressed by paul halmos : " mathematics is not a deductive science — that ' s a cliche. when you try to prove a theorem, you don ' t just list the hypotheses, and then start to reason. what you do is trial and error, experimentation, guesswork. you want to find out what the facts are, and what you do is in that respect similar to what a laboratory technician does. " = = history = = mathematicians have always practiced experimental mathematics. existing records of early mathematics, such as babylonian mathematics, typically consist of lists of numerical examples illustrating algebraic identities. however, modern mathematics, beginning in the 17th century, developed a tradition of publishing results in a final, formal and abstract presentation. the numerical examples that may have led a mathematician to originally formulate a general theorem were not published, and were generally forgotten. experimental mathematics as a separate area of study re - emerged in the twentieth century, when the invention of the electronic computer vastly increased the range of feasible calculations, with a speed and precision far greater than anything available to previous generations of mathematicians. a significant milestone and achievement of experimental mathematics was the discovery in 1995 of the bailey – borwein – plouffe formula for the binary digits of π. this formula was discovered not by formal reasoning, but instead by numerical searches on a computer ; only afterwards was a rigorous proof found. = = objectives and uses = = the objectives of experimental mathematics are " to generate understanding and insight ; to generate and confirm or confront conjectures ; and generally to make mathematics more tangible, lively and fun for both the professional researcher and the novice ". the uses of experimental mathematics have been defined as follows : gaining insight and intuition. discovering new patterns and relationships. using graphical displays to suggest underlying mathematical principles. testing and especially falsifying conjectures. exploring a possible result to see if it is worth formal proof. suggesting approaches for formal proof. replacing lengthy hand derivations with computer - based derivations. confirming analytically derived results. = = tools and techniques = = experimental mathematics makes use | https://en.wikipedia.org/wiki/Experimental_mathematics |
for a complete understanding of the qcd phase diagram it is important to connect first - principle thermodynamic calculations to experimental data from the rhic beam energy scan and the future experimental facilities fair, gsi, and nica, dubna. this can only be achieved by a realistic modeling of the dynamical evolution of critical fluctuations in heavy - ion collisions at the qcd phase transition. in this note i will summarize the current status of these dynamical models and highlight some of the important issues, which need to be addressed in the future. | arxiv:1510.08146 |
we report conductance measurements of a ballistic one - dimensional ( 1d ) wire defined in the lower two - dimensional electron gas of a gaas / algaas double quantum well. at low temperatures there is an additional structure at $ 0. 7 ( 2e ^ 2 / h ) $ in the conductance, which tends to $ e ^ 2 / h $ as the electron density is decreased. we find evidence for complete spin polarization in a weakly disorderd 1d wire at zero magnetic field through the observation of a conductance plateau at $ e ^ 2 / h $, which strengthens in an in - plane magnetic field and disappears with increasing electron density. in all cases studied, with increasing temperature structure occurs at $ 0. 6 ( 2e ^ 2 / h ) $. we suggest that the 0. 7 structure is a many - body spin state excited out of, either the spin - polarized electron gas at low densities, or the spin - degenerate electron gas at high densities. | arxiv:cond-mat/0005075 |
euler ' s elastica is defined by a critical point of the total squared curvature under the fixed length constraint, and its $ l ^ p $ - counterpart is called $ p $ - elastica. in this paper we completely classify all $ p $ - elasticae in the plane and obtain their explicit formulae as well as optimal regularity. to this end we introduce new types of $ p $ - elliptic functions which streamline the whole argument and result. as an application we also classify all closed planar $ p $ - elasticae. | arxiv:2203.08535 |
the aim of this thesis is to question some of the basic assumptions that go into building the $ \ lambda $ cdm model of our universe. the assumptions we focus on are the initial conditions of the universe, the fundamental forces in the universe on large scales and the approximations made in analysing cosmological data. for each of the assumptions we outline the theoretical understanding behind them, the current methods used to study them and how they can be improved and finally we also perform numerical analysis to quantify the novel solutions / methods we propose to extend the previous assumptions. | arxiv:2006.12126 |
) models used in the trade study process. this section focuses on the last. the main reason for using mathematical models and diagrams in trade studies is to provide estimates of system effectiveness, performance or technical attributes, and cost from a set of known or estimable quantities. typically, a collection of separate models is needed to provide all of these outcome variables. the heart of any mathematical model is a set of meaningful quantitative relationships among its inputs and outputs. these relationships can be as simple as adding up constituent quantities to obtain a total, or as complex as a set of differential equations describing the trajectory of a spacecraft in a gravitational field. ideally, the relationships express causality, not just correlation. furthermore, key to successful systems engineering activities are also the methods with which these models are efficiently and effectively managed and used to simulate the systems. however, diverse domains often present recurring problems of modeling and simulation for systems engineering, and new advancements are aiming to cross - fertilize methods among distinct scientific and engineering communities, under the title of ' modeling & simulation - based systems engineering '. = = = modeling formalisms and graphical representations = = = initially, when the primary purpose of a systems engineer is to comprehend a complex problem, graphic representations of a system are used to communicate a system ' s functional and data requirements. common graphical representations include : functional flow block diagram ( ffbd ) model - based design data flow diagram ( dfd ) n2 chart idef0 diagram use case diagram sequence diagram block diagram signal - flow graph usl function maps and type maps enterprise architecture frameworks a graphical representation relates the various subsystems or parts of a system through functions, data, or interfaces. any or each of the above methods is used in an industry based on its requirements. for instance, the n2 chart may be used where interfaces between systems are important. part of the design phase is to create structural and behavioral models of the system. once the requirements are understood, it is now the responsibility of a systems engineer to refine them and to determine, along with other engineers, the best technology for a job. at this point starting with a trade study, systems engineering encourages the use of weighted choices to determine the best option. a decision matrix, or pugh method, is one way ( qfd is another ) to make this choice while considering all criteria that are important. the trade study in turn informs the design, which again affects graphic representations of the system ( without changing the requirements ). in an se process, this stage represents the it | https://en.wikipedia.org/wiki/Systems_engineering |
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