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stone locales together with continuous maps form a coreflective subcategory of spectral locales and perfect maps. a proof in the internal language of an elementary topos was previously given by the second - named author. this proof can be easily translated to univalent type theory using resizing axioms. in this work, we show how to achieve such a translation without resizing axioms, by working with large, locally small, and small complete frames with small bases. this turns out to be nontrivial and involves predicative reformulations of several fundamental concepts of locale theory.
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arxiv:2301.04728
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recently, we developed a strategy to analyse the b - > pi pi, pi k data. we found that the b - > pi pi measurements can be accommodated in the standard model ( sm ) through large non - factorizable effects. on the other hand, our analysis of the ratios r _ c and r _ n of the cp - averaged branching ratios of the charged and neutral b - > pi k modes, respectively, suggested new physics ( np ) in the electroweak penguin sector, which may have a powerful interplay with rare decays. in this paper, we confront our strategy with recent experimental developments, addressing also the direct cp violation in b _ d - > pi ^ - + k ^ + -, which is now an established effect, the relation to its counterpart in b ^ + - - > pi ^ 0 k ^ + -, and the first results for the direct cp asymmetry of b _ d - > pi ^ 0 pi ^ 0 that turn out to be in agreement with our prediction. we obtain hadronic b - > pi pi, pi k parameters which are almost unchanged and arrive at an allowed region for the unitarity triangle in perfect accordance with the sm. the ` ` b - > pi k puzzle ' ' persists, and can still be explained through np, as in our previous analysis. in fact, the recently observed shifts in the experimental values of r _ c and r _ n have been predicted in our framework on the basis of constraints from rare decays. conversely, we obtain a moderate deviation of the ratio r of the cp - averaged b _ d - > pi ^ - + k ^ + - and b ^ + - - > pi ^ + - k rates from the current experimental value. however, using the emerging signals for b ^ + - - > k ^ + - k modes, this effect can be attributed to certain hadronic effects, which have a minor impact on r _ c and do not at all affect r _ n. our results for rare decays remain unchanged.
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arxiv:hep-ph/0410407
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the need for fast sparse optimization is emerging, e. g., to deal with large - dimensional data - driven problems and to track time - varying systems. in the framework of linear sparse optimization, the iterative shrinkage - thresholding algorithm is a valuable method to solve lasso, which is particularly appreciated for its ease of implementation. nevertheless, it converges slowly. in this paper, we develop a proximal method, based on logarithmic regularization, which turns out to be an iterative shrinkage - thresholding algorithm with adaptive shrinkage hyperparameter. this adaptivity substantially enhances the trajectory of the algorithm, in a way that yields faster convergence, while keeping the simplicity of the original method. our contribution is twofold : on the one hand, we derive and analyze the proposed algorithm ; on the other hand, we validate its fast convergence via numerical experiments and we discuss the performance with respect to state - of - the - art algorithms.
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arxiv:2501.12236
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in today ' s interconnected digital landscape, the proliferation of malware poses a significant threat to the security and stability of computer networks and systems worldwide. as the complexity of malicious tactics, techniques, and procedures ( ttps ) continuously grows to evade detection, so does the need for advanced methods capable of capturing and characterizing malware behavior. the current state of the art in malware classification and detection uses task specific objectives ; however, this method fails to generalize to other downstream tasks involving the same malware class. in this paper, the authors introduce a novel method that combines convolutional neural networks, standard graph embedding techniques, and a metric learning objective to extract meaningful information from network flow data and create strong embeddings characterizing malware behavior. these embeddings enable the development of highly accurate, efficient, and generalizable machine learning models for tasks such as malware strain classification, zero day threat detection, and closest attack type attribution as demonstrated in this paper. a shift from task specific objectives to strong embeddings will not only allow rapid iteration of cyber - threat detection models, but also allow different modalities to be introduced in the development of these models.
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arxiv:2305.15488
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this paper presents a slot antenna array with a reconfigurable radar cross section ( rcs ). the antenna system is formed by combining a liquid absorber with a 2 * 2 slot antenna array. the liquid absorber consists of a polymethyl methacrylate ( pmma ) container, a 45 % ethanol layer, and a metal ground, which is attached to the surface of the slot antenna array. the incident wave can be absorbed by the absorber rather than reflected in other directions when the pmma container is filled with ethanol, which reduces the monostatic and bistatic rcs. thus the rcs of the antenna can be changed by injecting and extracting ethanol while the antenna ' s radiation performance in terms of bandwidth, radiation patterns and gain is well sustained. in a complex communication system, this can be used to switch between detection and stealth mode. the mechanism of the absorber is investigated. the simulated results show that the antenna with this absorber has monostatic and bistatic rcs reduction bands from 2. 0 ghz to 18. 0 ghz, a maximum rcs reduction of 35 db with an average rcs reduction of 13. 28 db. the antenna ' s operating band is 100 mhz. without ethanol, the antenna has a realized gain of 12. 1 dbi, and it drops by 2 db when the lossy ethanol is injected. the measured results agree well with the simulated ones.
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arxiv:2110.15044
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several multi - winner systems that use approval voting have been developed but they each suffer from various problems. six of these methods are discussed in this paper. they are satisfaction approval voting, minimax approval voting, proportional approval voting, monroe ' s fully proportional representation, chamberlin - courant ' s rule, and ebert ' s method. they all fail at least one of proportional representation ( pr ), strong pr, monotonicity or positive support. however, the new method described in this paper - proportional approval method using squared loads, approval removal and coin - flip approval transformation ( pamsac ) - passes them all. pamsac uses the squared loads of ebert ' s method, but removes non - beneficial approvals to restore monotonicity. it also uses the coin - flip approval transformation ( cfat ), where voters are " split " into two for each candidate they approve, and where one half of this split voter approves and the other half does not approve each candidate approved on the ballot. this restores positive support, and also makes the method equivalent to the d ' hondt party - list method for party voting. pamsac reduces to simple approval voting in the single - winner case. a score voting version is described that also reduces to simple score voting in the single - winner case.
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arxiv:1602.05248
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overheads incurred by routing protocols diminish the capacity available for relaying useful data in a mobile wireless ad hoc network. discovering lower bounds on the amount of protocol overhead incurred for routing data packets is important for the development of efficient routing protocols, and for characterizing the actual ( effective ) capacity available for network users. this paper presents an information - theoretic framework for characterizing the minimum routing overheads of geographic routing in a network with mobile nodes. specifically, the minimum overhead problem is formulated as a rate - distortion problem. the formulation may be applied to networks with arbitrary traffic arrival and location service schemes. lower bounds are derived for the minimum overheads incurred for maintaining the location of destination nodes and consistent neighborhood information in terms of node mobility and packet arrival process. this leads to a characterization of the deficit caused by the routing overheads on the overall transport capacity.
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arxiv:cs/0703050
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this paper explores public perceptions around the role of affective computing in the workplace. it uses a series of design fictions with 46 uk based participants, unpacking their perspectives on the advantages and disadvantages of tracking the emotional state of workers. the scenario focuses on mundane uses of biometric sensing in a sales environment, and how this could shape management approaches with workers. the paper structure is as follows : section 1 provides a brief introduction ; section 2 provides an overview of the innovative design fiction methodology ; section 3 explores wider shifts around it in the workplace ; section 4 provides some legal analysis exploring emergence of ai in the workplace ; and section 5 presents themes from the study data. the latter section includes discussion on concerns around functionality and accuracy of affective computing systems, and their impacts on surveillance, human agency, and worker / management interactions.
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arxiv:2205.08264
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we report the detection of a short - lived narrow quasi - periodic oscillation ( qpo ) at ~ 88 mhz in an insight - hxmt observation during the soft state of the persistent black hole high mass x - ray binary cygnus x - 1. this qpo is significantly detected in all the three instruments of insight - hxmt, so in the broad energy range 1 - 250 kev. the fractional rms of the qpo does not show significant variations above 3 kev ( ~ 5 % ) while decreases at lower energy ( ~ 2 % ). we show that this qpo is different from the type - a, - b, and - c qpos usually observed in black hole x - ray binaries. we compare qpos at similar frequencies that have been previously detected in other persistent high - mass x - ray binaries in the soft state ; we speculate that such qpos might relate to some local inhomogeneity rarely formed in the accretion flow of wind - fed accretion systems.
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arxiv:2104.14307
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angle - resolved photoemission spectroscopy ( arpes ) is a powerful technique for the study of electronic structure, but it lacks a direct ability to study buried interfaces between two materials. we address this limitation by combining arpes with soft x - ray standing - wave ( sw ) excitation ( swarpes ), in which the sw profile is scanned through the depth of the sample. we have studied the buried interface in a prototypical magnetic tunnel junction la0. 7sr0. 3mno3 / srtio3. depth - and momentum - resolved maps of mn 3d eg and t2g states from the central, bulk - like and interface - like regions of la0. 7sr0. 3mno3 exhibit distinctly different behavior consistent with a change in the mn bonding at the interface. we compare the experimental results to state - of - the - art density - functional and one - step photoemission theory, with encouraging agreement that suggests wide future applications of this technique.
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arxiv:1309.2022
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we study a mesoscopic metallic ring threaded by a magnetic flux which varies linearly in time phim ( t ) = phi t with a formalism based in baym - kadanoff - keldysh non - equilibrium green functions. we propose a method to calculate the green functions in real space and we consider an experimental setup to investigate the dynamics of the ring by recourse to a transport experiment. this consists in a single lead connecting the ring to a particle reservoir. we show that different dynamical regimes are attained depending on the ratio hbar phi / phi0 w, being phi0 = h c / e and w, the bandwidth of the ring. for moderate lengths of the ring, a stationary regime is achieved for hbar phi / phi0 > w. in the opposite case with hbar phi / phi0 < w, the effect of bloch oscillations driven by the induced electric field manifests itself in the transport properties of the system. in particular, we show that in this time - dependent regime a tunneling current oscillating in time with a period tau = 2piphi0 / phi can be measured in the lead. we also analyze the resistive effect introduced by inelastic scattering due to the coupling to the external reservoir.
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arxiv:cond-mat/0203410
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some species of purple bacteria as, e. g., rhodobacter sphaeroides contain the protein pufx. concurrently, the light harvesting complexes 1 ( lh1 ) form dimers of open rings. in mutants without pufx, the lh1s are closed rings and photosynthesis breaks down, because the ubiquinone exchange at the reaction center is blocked. thus, pufx is regarded essential for quinone exchange. in contrast to this view, which implicitly treats the lh1s as obstacles to photosynthesis, we propose that the primary purpose of pufx is to improve the efficiency of light harvesting by inducing the lh1 dimerization. calculations with a dipole model, which compare the photosynthetic efficiency of various configurations of monomeric and dimeric core complexes, show that the dimer can absorb photons directly into the rc about 30 % more efficient, when related to the number of bacteriochlorophylls, but that the performance of the more sophisticated dimeric lh1 antenna degrades faster with structural perturbations. the calculations predict an optimal orientation of the reaction centers relative to the lh1 dimer, which agrees well with the experimentally found configuration. for the increased required rigidity of the dimer additional modifications of the lh1 subunits are necessary, which would lead to the observed ubiquinone blockage, when pufx is missing.
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arxiv:q-bio/0605023
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we present new, exceptionally efficient proofs of poisson - - dirichlet limit theorems for the scaled sizes of irreducible components of random elements in the classic combinatorial contexts of arbitrary assemblies, multisets, and selections, when the components generating functions satisfy certain standard hypotheses. the proofs exploit a new criterion for poisson - - dirichlet limits, originally designed for rapid proofs of billingsley ' s theorem on the scaled sizes of log prime factors of random integers ( and some new generalizations ). unexpectedly, the technique applies in the present combinatorial setting as well, giving, perhaps, a long sought - after unifying point of view. the proofs depend also on formulas of arratia and tavar { \ ' e } for the mixed moments of counts of components of various sizes, as well as formulas of flajolet and soria for the asymptotics of generating function coefficients.
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arxiv:1401.1556
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the superfluid phase transition dynamics and associated spontaneous vortex formation with the crossing of the critical temperature in a disk geometry is studied in the framework of the $ ads / cft $ correspondence by solving the einstein - abelian - higgs model in an $ ads _ 4 $ black hole. for a slow quench, the vortex density admits a universal scaling law with the cooling rate as predicted by the kibble - zurek mechanism ( kzm ), while for fast quenches, the density shows a universal scaling behavior as a function of the final temperature, that lies beyond the kzm prediction. the vortex number distribution in both the power - law and saturation regimes can be approximated by a normal distribution. however, the study of the universal scaling of the cumulants reveals non - normal features and indicates that vortex statistics in the newborn superfluid is best described by the poisson binomial distribution, previously predicted in the kzm regime [ phys. rev. lett. 124, 240602 ( 2020 ) ]. this is confirmed by studying the cumulant scalings as a function of the quench time and the quench depth. our work supports the existence of a universal defect number distribution that accommodates the kzm scaling, its breakdown at fast quenches, and the additional universal scaling laws as a function of the final value of the control parameter.
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arxiv:2406.09433
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this paper presents a new optical system for detecting light signals associated with the change in incoming photon number. the system employs quantum correlation of photon pairs created via spontaneous parametric down - conversion ( spdc ). the signal, if present, will perturb the flux of the incident photon stream. the perturbed photon stream is first projected through a birefringent crystal where spdc occurs, converting a single high - energy photon into a pair of low energy photons. the photons in each pair eventually arrive at separate detectors. by examining the biphoton correlation using the probability distribution of the photons at the detectors, which varies depending on the displacement of the main pump photon stream and the change in the number of photons, the small optical displacement of the photon stream and its variance can be determined. the change in incident photon number, in other words, the presence of light signal does not influence the average of the measured optical displacement values. nevertheless, the change in optical displacement measurement variance when the number of incident photons has changed detects the light signal. this optical setup enables the detection of light signals with low noise and remarkably high precision and sensitivity using quantum correlation. the proposed technique has potential application for axion - like particle search in experimental high energy physics.
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arxiv:1907.10757
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this paper aims to reduce randomness in football by analysing the role of lineups in final scores using machine learning prediction models we have developed. football clubs invest millions of dollars on lineups and knowing how individual statistics translate to better outcomes can optimise investments. moreover, sports betting is growing exponentially and being able to predict the future is profitable and desirable. we use machine learning models and historical player data from english premier league ( 2020 - 2022 ) to predict scores and to understand how individual performance can improve the outcome of a match. we compared different prediction techniques to maximise the possibility of finding useful models. we created heuristic and machine learning models predicting football scores to compare different techniques. we used different sets of features and shown goalkeepers stats are more important than attackers stats to predict goals scored. we applied a broad evaluation process to assess the efficacy of the models in real world applications. we managed to predict correctly all relegated teams after forecast 100 consecutive matches. we show that support vector regression outperformed other techniques predicting final scores and that lineups do not improve predictions. finally, our model was profitable ( 42 % return ) when emulating a betting system using real world odds data.
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arxiv:2210.06327
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different approaches are used for the calculation of the sm - like higgs boson mass in the mssm : the fixed - order diagrammatic approach is accurate for low susy scales ; the eft approach, for high susy scales. hybrid approaches, combining fixed - order and eft calculations, allow to obtain a precise prediction also for intermediary susy scales. here, we briefly discuss the hybrid approach implemented into the code feynhiggs. in addition, we show how the refined higgs mass prediction was used to define new mssm higgs benchmark scenarios.
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arxiv:1905.04918
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the unit cell of a chevronic sculptured thin film ( chevstf ) comprises two identical columnar thin films ( ctfs ) except that the nanocolumns of the first are oriented at an angle \ chi and nanocolumns of the second are oriented at an angle \ pi - \ chi with respect to the interface of the two ctfs. a chevstf containing 10 unit cells was fabricated using resistive - heating physical vapor deposition of zinc selenide. planewave reflectance and transmittance spectrums of this chevstf were measured for a wide variety of incidence conditions over the 500 - - 900 - nm range of the free - space wavelength. despite its structural periodicity, the chevstf did not exhibit the bragg phenomenon. theoretical calculations with the ctfs modeled as biaxial dielectric materials indicated that the bragg phenomenon would not be manifested for normal and near - normal incidence, but vestigial manifestation was possible for suffciently oblique incidence. thus, structural periodicity does not always lead to electromagnetic periodicity that underlies the exhibition of the bragg phenomenon.
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arxiv:1707.00363
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recent observational indications of an accelerating universe enhance the interest in studying models with a cosmological constant. we investigate cosmological expansion ( frw metric ) with $ \ lambda > 0 $ for a general linear equation of state $ p = w \ rho $, $ w > - 1 $, so that the interplay between cosmological vacuum and quintessence is allowed, as well. four closed - form solutions ( flat universe with any $ w $, and $ w = 1 / 3 $, $ - 1 / 3, - 2 / 3 $ ) are given, in a proper compact representation. various estimates of the expansion are presented in a general case when no closed - form solutions are available. for the open universe a simple relation between solutions with different parameters is established : it turns out that a solution with some $ w $ and ( properly scaled ) $ \ lambda $ is expressed algebraically via another solution with special different values of these parameters. the expansion becomes exponential at large times, and the amplitude at the exponent depends on the parameters. we study this dependence in detail, deriving various representations for the amplitude in terms of integrals and series. the closed - form solutions serve as benchmarks, and the solution transformation property noted above serves as a useful tool. among the results obtained, one is that for the open universe with relatively small cosmological constant the amplitude is independent of the equation of state. also, estimates of the cosmic age through the observable ratio $ \ omega _ \ lambda / \ omega _ m $ and parameter $ w $ are given ; when inverted, they provide an estimate of $ w $, i. e., the state equation, through the known $ \ omega _ \ lambda / \ omega _ m $ and age of the universe.
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arxiv:astro-ph/0208465
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in this paper, we investigate the issue of spectrum assignment in crns and examine various opportunistic spectrum access approaches proposed in the literature. we provide insight into the efficiency of such approaches and their ability to attain their design objectives. we discuss the factors that impact the selection of the appropriate operating channel ( s ), including the important interaction between the cognitive linkquality conditions and the time - varying nature of prns. protocols that consider such interaction are described. we argue that using best quality channels does not achieve the maximum possible throughput in crns ( does not provide the best spectrum utilization ). the impact of guard bands on the design of opportunistic spectrum access protocols is also investigated. various complementary techniques and optimization methods are underlined and discussed, including the utilization of variablewidth spectrum assignment, resource virtualization, full - duplex capability, cross - layer design, beamforming and mimo technology, cooperative communication, network coding, discontinuousofdm technology, and software defined radios. finally, we highlight several directions for future research in this field.
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arxiv:1605.02230
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we have developed an interactive program which shows the solar energetic particle ( sep ) intensity - time profile as observed by soho / erne, simultaneously with the associated coronal mass ejection in optical imaging movies taken by lasco coronagraph, soft x - ray by yohkoh, ultraviolet by eit, dh radio emission by wave / wind, and the h $ \ alpha $ location for the solar flare and spectral radio emission from the journal of geophysical data. the whole set of data will provide increased scientific knowledge on the solar energetic particle events and the solar phenomena associated with them, because in this program one can see easily the temporal associations of each phenomenon during the evolution of the particle intensity. the ( sep ) intensity - time profile will give a clear view to detect the velocity dispersion in the events, if it exists. the erne data are commented in order to follow of phenomena associated with changes of the intensity - time profiles. we introduce this set of data as an index for the erne / soho solar energetic particle events. the interactive program is applied for statistical, correlative study of sep events observed on board soho.
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arxiv:astro-ph/0607191
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doubly charged scalars, predicted in many models having exotic higgs representations, can in general have lepton - number violating ( lfv ) couplings. we show that by using an associated monoenergetic final state photon seen at a future linear e - e - collider, we can have a clear and distinct signature for a doubly - charged resonance. the strength of the delta l = 2 coupling can also be probed quite effectively as a function of the recoil mass of the doubly - charged scalar.
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arxiv:hep-ph/0608112
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we study renormalisation group ( rg ) corrections relevant for leptogenesis in the case of family symmetry models such as the altarelli - feruglio a4 model of tri - bimaximal lepton mixing or its extension to tri - maximal mixing. such corrections are particularly relevant since in large classes of family symmetry models, to leading order, the cp violating parameters of leptogenesis would be identically zero at the family symmetry breaking scale, due to the form dominance property. we find that rg corrections violate form dominance and enable such models to yield viable leptogenesis at the scale of right - handed neutrino masses. more generally, the results of this paper show that rg corrections to leptogenesis cannot be ignored for any family symmetry model involving sizeable neutrino and tau yukawa couplings.
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arxiv:1110.5676
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this paper presents experimental verification of below - cutoff transmission through miniaturized waveguides whose interior is coated with a thin anisotropic metamaterial liner possessing epsilon - negative and near - zero ( ennz ) properties. these liners are realized using a simple, printed - circuit implementation based on inductively loaded wires, and introduce an he $ _ { 11 } $ mode well below the natural cutoff frequency. the inclusion of the liner is shown to substantially improve the transmission between two embedded shielded - loop sources. a homogenization scheme is developed to characterize the liner ' s anisotropic effective - medium parameters, which is shown to accurately describe a set of frequency - reduced cutoffs. the fabrication of the lined waveguide is discussed, and the experimental and simulated transmission results are shown to be in agreement.
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arxiv:1510.07554
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the astrophysical $ s $ factor and reaction rates of the direct capture process $ ^ { 6 } $ li ( p, $ \ gamma ) ^ { 7 } $ be are estimated within a two - body single - channel potential model approach. central potentials of the gaussian - form in the $ ^ 2p _ { 3 / 2 } $ and $ ^ 2p _ { 1 / 2 } $ waves are adjusted to reproduce the binding energies and the empirical values of the asymptotic normalization coefficients ( anc ) for the $ ^ 7 $ be ( 3 / 2 $ ^ - $ ) ground and $ ^ 7 $ be ( 1 / 2 $ ^ - $ ) excited bound states, respectively. the parameters of the potential in the most important $ ^ 2s _ { 1 / 2 } $ scattering channel were fitted to reproduce the empirical phase shifts from the literature and the low - energy astrophysical $ s $ factor of the luna collaboration. the obtained results for the astrophysical $ s $ factor and the reaction rates are in a very good agreement with available experimental data sets. the numerical estimates reproduce not only the absolute values, but also the energy and temperature dependence of the $ s $ factor and reaction rates of the luna collaboration, respectively. the estimated $ ^ { 7 } { \ rm li / h } $ primordial abundance ratio $ ( 4. 67 \ pm 0. 04 ) \ times 10 ^ { - 10 } $ is well consistent with recent bbn result of $ ( 4. 72 \ pm 0. 72 ) \ times 10 ^ { - 10 } $ after the planck observation.
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arxiv:2306.12838
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we introduce a generalization of communication of partial ignorance where both parties of a prepare - and - measure setup receive inputs from a third party before a success metric is maximized over the measurements and preparations. various methods are used to obtain bounds on the success metrics, including sdps, ultraweak monotones for communication matrices and frame theory for quantum states. simplest scenarios in the new generalized prepare - and - measure setting, simply called partial ignorance communication tasks, are analysed exhaustively for bits and qudits. finally, the new generalized setting allows the introduction of operational equivalences to the preparations and measurements, allowing us to analyse and observe a contextual advantage for quantum theory in one of the communication tasks.
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arxiv:2202.08581
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in barter exchanges agents enter seeking to swap their items for other items on their wishlist. we consider a centralized barter exchange with a set of agents and items where each item has a positive value. the goal is to compute a ( re ) allocation of items maximizing the agents ' collective utility subject to each agent ' s total received value being comparable to their total given value. many such centralized barter exchanges exist and serve crucial roles ; e. g., kidney exchange programs, which are often formulated as variants of directed cycle packing. we show finding a reallocation where each agent ' s total given and total received values are equal is np - hard. on the other hand, we develop a randomized algorithm that achieves optimal utility in expectation and where, i ) for any agent, with probability 1 their received value is at least their given value minus $ v ^ * $ where $ v ^ * $ is said agent ' s most valuable owned and wished - for item, and ii ) each agent ' s given and received values are equal in expectation.
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arxiv:2406.13983
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we consider a bose - hubbard model with an arbitrary hopping term and provide the boundary of the insulating phase thereof in terms of third - order strong coupling perturbative expansions for the ground state energy. in the general case two previously unreported terms occur, arising from triangular loops and hopping inhomogeneities, respectively. quite interestingly the latter involves the entire spectrum of the hopping matrix rather than its maximal eigenpair, like the remaining perturbative terms. we also show that hopping inhomogeneities produce a first order correction in the local density of bosons. our results apply to ultracold bosons trapped in confining potentials with arbitrary topology, including the realistic case of optical superlattices with uneven hopping amplitudes. significant examples are provided. furthermore, our results can be extented to magnetically tuned transitions in josephson junction arrays.
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arxiv:cond-mat/0406467
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an efficient method with no numerical diagonalization of a huge hamiltonian matrix and calculation of a tedious green ' s function is proposed to acquire the exact energy spectrum and dynamical conductivity in a gated aa - stacking $ n $ - layer graphene ( aanlg ) with the intrinsic spin - orbital coupling ( soc ). $ 2n \ times 2n $ tight - binding hamiltonian matrix, velocity operator and green ' s function representation of an aanlg are simultaneously reduced to $ n $ $ 2 \ times 2 $ diagonal block matrices through a proper transformation matrix. a gated aanlg with intrinsic soc is reduced to $ n $ graphene - like layers. the energy spectrum of a graphene - like layer is $ e = \ varepsilon _ { \ bot } \ pm \ varepsilon _ { | | } $. $ \ varepsilon _ { \ bot } $ depends on the interlayer interaction, gated voltage and layer number. $ \ varepsilon _ { | | } = \ sqrt { e _ { mg } ^ 2 + \ delta ^ 2 } $, where $ e _ { mg } $ is the energy spectrum of a monolayer graphene and $ \ delta $ is the magnitude of intrinsic soc. more importantly, by inserting the diagonal block velocity operator and green ' s function representation in the kubo formula, the exact dynamical conductivity of an aanlg is shown to be $ \ sigma = \ sigma _ { j = 1 } ^ n \ sigma _ j $, the sum of the dynamical conductivity of $ n $ graphene - like layers. the analytical form of $ \ sigma _ j $ is presented and the dependence of $ \ sigma _ j $ on $ \ varepsilon _ { \ bot } $, $ \ delta $, and chemical potential is clearly demonstrated. moreover, the effect of rashba soc on the electronic properties of an aanlg is explored with the exact energy spectrum presented.
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arxiv:1502.04447
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tropical diseases like \ textit { chikungunya } and \ textit { zika } have come to prominence in recent years as the cause of serious, long - lasting, population - wide health problems. in large countries like brasil, traditional disease prevention programs led by health authorities have not been particularly effective. we explore the hypothesis that monitoring and analysis of social media content streams may effectively complement such efforts. specifically, we aim to identify selected members of the public who are likely to be sensitive to virus combat initiatives that are organised in local communities. focusing on twitter and on the topic of zika, our approach involves ( i ) training a classifier to select topic - relevant tweets from the twitter feed, and ( ii ) discovering the top users who are actively posting relevant content about the topic. we may then recommend these users as the prime candidates for direct engagement within their community. in this short paper we describe our analytical approach and prototype architecture, discuss the challenges of dealing with noisy and sparse signal, and present encouraging preliminary results.
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arxiv:1703.03928
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we obtain an upper bound on the minimal number of points in an $ \ epsilon $ - chain joining two points in a metric space. this generalizes a bound due to hambly and kumagai ( 1999 ) for the case of resistance metric on certain self - similar fractals. as an application, we deduce a condition on $ \ epsilon $ - chains introduced by grigor ' yan and telcs ( 2012 ). this allows us to obtain sharp bounds on the heat kernel for spaces satisfying the parabolic harnack inequality without assuming further conditions on the metric. a snowflake transform on the euclidean space shows that our bound is sharp.
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arxiv:1909.09988
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we perform an extrapolative analysis of " fast - growth " free - energy - difference ( df ) estimates of a computer - modeled, fully - solvated ethane < - > methanol transformation. the results suggest that extrapolation can greatly reduce the systematic error in df estimated from a small number of very fast switches. our extrapolation procedure uses block - averages of finite - data estimates, and appears to be particularly useful for broad, non - gaussian distributions of data which produce substantial systematic errors with insufficient data. in every tested case, the extrapolative results were better than direct estimates.
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arxiv:physics/0107066
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two necessary and sufficient conditions for an operator to be semi - normal are revealed. for a volterra integration operator the set where the operator and its adjoint are metrically equal is described.
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arxiv:1410.5265
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we solve analytically the kadanoff - baym equations for a noninteracting junction connected to an arbitrary number of noninteracting wide - band terminals. the initial equilibrium state is properly described by the addition of an imaginary track to the time contour. from the solution we obtain the time - dependent electron densities and currents within the junction. the final results are analytic expressions as a function of time, and therefore no time propagation is needed - either in transient or in steady - state regimes. we further present and discuss some applications of the obtained formulae.
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arxiv:1303.6201
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high - gradient and high - efficiency acceleration in plasma - based accelerators has been demonstrated, showing its potential as the building block for a future collider operating at the energy frontier of particle physics. however, generating and accelerating the required spin - polarized beams in such a collider using plasma - based accelerators has been a long - standing challenge. here we show that the passage of a highly relativistic, high - current electron beam through a single - species ( ytterbium ) vapor excites a nonlinear plasma wake by primarily ionizing the two outer 6s electrons. further photoionization of the resultant yb2 + ions by a circularly polarized laser injects the 4f14 electrons into this wake generating a highly spin - polarized beam. combining time - dependent schrodinger equation simulations with particle - in - cell simulations, we show that a sub - femtosecond, high - current ( 4 ka ) electron beam with up to 56 % net spin polarization can be generated and accelerated to 15 gev in just 41 cm. this relatively simple scheme solves the perplexing problem of producing spin - polarized relativistic electrons in plasma - based accelerators.
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arxiv:2206.09017
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an automorphic self dual l - function has the super - positivity property if all derivatives of the completed l - function at the central point $ s = 1 / 2 $ are non - negative and all derivatives at a real point $ s > 1 / 2 $ are positive. in this paper we prove that at least 12 % of l - functions associated to hecke basis cusp forms of weight $ 2 $ and large prime level $ q $ have the super - positivity property. it is also shown that at least 49 % of such l - functions have no real zeros on $ \ re ( s ) > 0 $ except possibly at $ s = 1 / 2. $
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arxiv:1803.05394
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structure. polymers display varying degrees of crystallinity, and many are completely non - crystalline. glass, some ceramics, and many natural materials are amorphous, not possessing any long - range order in their atomic arrangements. the study of polymers combines elements of chemical and statistical thermodynamics to give thermodynamic and mechanical descriptions of physical properties. = = = = nanostructure = = = = materials, which atoms and molecules form constituents in the nanoscale ( i. e., they form nanostructures ) are called nanomaterials. nanomaterials are the subject of intense research in the materials science community due to the unique properties that they exhibit. nanostructure deals with objects and structures that are in the 1 – 100 nm range. in many materials, atoms or molecules agglomerate to form objects at the nanoscale. this causes many interesting electrical, magnetic, optical, and mechanical properties. in describing nanostructures, it is necessary to differentiate between the number of dimensions on the nanoscale. nanotextured surfaces have one dimension on the nanoscale, i. e., only the thickness of the surface of an object is between 0. 1 and 100 nm. nanotubes have two dimensions on the nanoscale, i. e., the diameter of the tube is between 0. 1 and 100 nm ; its length could be much greater. finally, spherical nanoparticles have three dimensions on the nanoscale, i. e., the particle is between 0. 1 and 100 nm in each spatial dimension. the terms nanoparticles and ultrafine particles ( ufp ) often are used synonymously although ufp can reach into the micrometre range. the term ' nanostructure ' is often used, when referring to magnetic technology. nanoscale structure in biology is often called ultrastructure. = = = = microstructure = = = = microstructure is defined as the structure of a prepared surface or thin foil of material as revealed by a microscope above 25× magnification. it deals with objects from 100 nm to a few cm. the microstructure of a material ( which can be broadly classified into metallic, polymeric, ceramic and composite ) can strongly influence physical properties such as strength, toughness, ductility, hardness, corrosion resistance, high / low temperature behavior, wear resistance, and so on. most of the traditional materials ( such
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https://en.wikipedia.org/wiki/Materials_science
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different hadron transverse momentum spectra are calculated in a non - extensive statistical, quark - coalescence model. for the low - pt part a gluonic string contribution is conjectured, its length distribution and fractality are fitted to rhic data.
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arxiv:0812.2985
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according to \ cite { boss } and \ cite { m1 }, the ancestor correlators of any semi - simple cohomological field theory satisfy { \ em local } eynard - - orantin recursion. in this paper, we prove that for simple singularities, the local recursion can be extended to a global one. the spectral curve of the global recursion is an interesting family of riemann surfaces defined by the invariant polynomials of the corresponding weyl group. we also prove that for genus 0 and 1, the free energies introduced in \ cite { eo } coincide up to some constant factors with respectively the genus 0 and 1 primary potentials of the simple singularity.
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arxiv:1501.03677
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in this article, we present a gravitational collapse null dust solution of the einstein field equations. the spacetime is regular everywhere except on the symmetry axis where it possesses a naked curvature singularity, and admits one parameter isometry group, a generator of axial symmetry along the cylinder which has closed orbits. the space - time admits closed timelike curves ( ctcs ) which develop at some particular moment in a causally well - behaved manner and may represent a cosmic time machine. the radial geodesics near to the singularity, and the gravitational lensing ( gl ) will be discussed. the physical interpretation of this solution, based on the study of the equation of the geodesic deviation, will be presented. it was demonstrated that, this solution depends on the local gravitational field consisting of two components with amplitude $ \ psi _ 2 $, $ \ psi _ 4 $.
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arxiv:1705.05644
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in this article, the crystallization of polyethylene is investigated by the modified weighted density approximation. also a direct correlation function of polyethylene based on the rism theory is used. the free energy of a polyethylene is calculated using density functional theory. the crystallization together with solid and liquid densities are calculated and finally compared with the prism simulations and experimental results. the result obtained by modified weighted density approximation mwda is shown to be in a better agreement with the experimental results rather than the prism simulations.
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arxiv:1502.00368
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the pyrochlore osmate ho2os2o7 is a candidate material for a fragile j = 0 local singlet ground state, however little is known regarding the single - ion behavior of either the os or ho ions. to address this we present polarized neutron powder diffraction ( pnpd ) and resonant inelastic x - ray scattering ( rixs ) measurements that separately probe the local site behavior of the os and ho ions. the pnpd results are dominated by ho3 + scattering and the analysis reveals local site susceptibility behavior consistent with spin ice materials. complimentary unpolarized neutron powder diffraction show an ordered spin ice ground state in an applied magnetic field. to isolate the os4 + single - ion behavior we present resonant inelastic x - ray scattering ( rixs ) measurements at the osmium l - edge. analysis of the rixs spectra parameterize the spin - orbit coupling ( 0. 35 ev ), hund ' s coupling ( 0. 27 ev ) and trigonal distortion ( - 0. 17 ev ). the results are considered within the context of a j = 0 model and possible departures from this through structural distortions, excitonic interactions and 5d - 4f interactions between the os ion and the surrounding ho lattice. the experimental methodology employed highlights the complimentary information available in rare earth based 5d pyrochlores from distinct neutron and x - ray scattering techniques that allow for the isolation and determination of the behavior of the different ions.
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arxiv:2312.14811
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partially - observable problems pose a trade - off between reducing costs and gathering information. they can be solved optimally by planning in belief space, but that is often prohibitively expensive. model - predictive control ( mpc ) takes the alternative approach of using a state estimator to form a belief over the state, and then plan in state space. this ignores potential future observations during planning and, as a result, cannot actively increase or preserve the certainty of its own state estimate. we find a middle - ground between planning in belief space and completely ignoring its dynamics by only reasoning about its future accuracy. our approach, filter - aware mpc, penalises the loss of information by what we call " trackability ", the expected error of the state estimator. we show that model - based simulation allows condensing trackability into a neural network, which allows fast planning. in experiments involving visual navigation, realistic every - day environments and a two - link robot arm, we show that filter - aware mpc vastly improves regular mpc.
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arxiv:2304.10246
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high dimensionality comparable to sample size is common in many statistical problems. we examine covariance matrix estimation in the asymptotic framework that the dimensionality $ p $ tends to $ \ infty $ as the sample size $ n $ increases. motivated by the arbitrage pricing theory in finance, a multi - factor model is employed to reduce dimensionality and to estimate the covariance matrix. the factors are observable and the number of factors $ k $ is allowed to grow with $ p $. we investigate impact of $ p $ and $ k $ on the performance of the model - based covariance matrix estimator. under mild assumptions, we have established convergence rates and asymptotic normality of the model - based estimator. its performance is compared with that of the sample covariance matrix. we identify situations under which the factor approach increases performance substantially or marginally. the impacts of covariance matrix estimation on portfolio allocation and risk management are studied. the asymptotic results are supported by a thorough simulation study.
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arxiv:math/0701124
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advancing our understanding of astrophysical turbulence is bottlenecked by the limited resolution of numerical simulations that may not fully sample scales in the inertial range. machine learning ( ml ) techniques have demonstrated promise in up - scaling resolution in both image analysis and numerical simulations ( i. e., superresolution ). here we employ and further develop a physics - constrained convolutional neural network ( cnn ) ml model called " meshfreeflownet ' ' ( mffn ) for superresolution studies of turbulent systems. the model is trained both on the simulation images as well as the evaluated pdes, making it sensitive to the underlying physics of a particular fluid system. we develop a framework for 2d turbulent rayleigh - b \ ' enard convection ( rbc ) generated with the \ textsc { dedalus } code by modifying the mffn architecture to include the full set of simulation pdes and the boundary conditions. our training set includes fully developed turbulence sampling rayleigh numbers ( $ ra $ ) of $ ra = 10 ^ 6 - 10 ^ { 10 } $. we evaluate the success of the learned simulations by comparing the power spectra of the direct \ textsc { dedalus } simulation to the predicted model output, and compare both ground truth and predicted power spectral inertial range scalings to theoretical predictions. we find that the updated network performs well at all $ ra $ studied here in recovering large - scale information, including the inertial range slopes. the superresolution prediction is overly dissipative at smaller scales than that of the inertial range in all cases, but the smaller - scales are better recovered in more turbulent, than laminar, regimes. this is likely because more turbulent systems have a rich variety of structures at many length scales compared to laminar flows.
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arxiv:2307.02674
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the mixed morphology class of supernova remnants ( mmsnrs ) comprises a substantial fraction of observed remnants and yet there is as yet no consensus on their origin. a clue to their nature is the presence of regions that show x - ray evidence of recombining plasmas. recent calculations of remnant evolution in a cloudy interstellar medium ( ism ) that included thermal conduction but not non - equilibrium ionization ( nei ) showed promise in explaining observed surface brightness distributions but could not determine if recombining plasmas were present. in this paper, we present numerical hydrodynamical models of mmsnrs in 2d and 3d including explicit calculation of nei effects. both the spatial ionization distribution and temperature - density diagrams show that recombination occurs inside the simulated mmsnr, and that both adiabatic expansion and thermal conduction cause recombination, albeit in different regions. features created by the adiabatic expansion stand out in the spatial and temperature - density diagrams, but thermal conduction also plays a role. thus thermal conduction and adiabatic expansion both contribute significantly to the cooling of high - temperature gas. realistic observational data are simulated with both spatial and spectral input from various regions. we also discuss the possibility of analyzing the sources of recombination and dominant hydrodynamical processes in observations using temperature - density diagrams and spatial maps.
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arxiv:1902.10718
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large language models ( llms ) have demonstrated remarkable capabilities in open - ended text generation tasks. however, the inherent open - ended nature of these tasks implies that there is always room for improvement in the quality of model responses. to address this challenge, various approaches have been proposed to enhance the performance of llms. there has been a growing focus on enabling llms to self - improve their response quality, thereby reducing the reliance on extensive human annotation efforts for collecting diverse and high - quality training data. recently, prompting - based methods have been widely explored among self - improvement methods owing to their effectiveness, efficiency, and convenience. however, those methods usually require explicitly and thoroughly written rubrics as inputs to llms. it is expensive and challenging to manually derive and provide all necessary rubrics with a real - world complex goal for improvement ( e. g., being more helpful and less harmful ). to this end, we propose an implicit self - improvement ( pit ) framework that implicitly learns the improvement goal from human preference data. pit only requires preference data that are used to train reward models without extra human efforts. specifically, we reformulate the training objective of reinforcement learning from human feedback ( rlhf ) - - instead of maximizing response quality for a given input, we maximize the quality gap of the response conditioned on a reference response. in this way, pit is implicitly trained with the improvement goal of better aligning with human preferences. experiments on two real - world datasets and one synthetic dataset show that our method significantly outperforms prompting - based methods.
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arxiv:2310.00898
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the problem of domain aiming control is formulated for controlled stochastic nonlinear systems. this issue involves regularity of the solution to the resulting closed - loop stochastic system. to begin with, an extended existence and uniqueness theorem for stochastic differential equation with local lipschitz coefficients is proven by using a lyapunov - type function. a lyapunov - based sufficient condition is also given under which there is no regularity of the solution for a class of stochastic differential equations. the notions of domain recurrence and residence time for stochastic nonlinear systems are introduced, and various criteria for the recurrence and non - recurrence relative to a bounded open domain or an unbounded domain are provided. furthermore, upper bounds of either the expectation or the moment - generating function of the residence time are derived. in particular, a connection between the mean residence time and a dirichlet problem is investigated and illustrated with a numerical example. finally, the problem of domain aiming control is considered for certain types of nonlinear and linear stochastic systems. several examples are provided to illustrate the theoretical results.
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arxiv:1807.03009
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we determine the dimension of every simple module for the algebra of the monoid of all relations on a finite set ( i. e. boolean matrices ). this is in fact the same question as the determination of the dimension of every evaluation of a simple correspondence functor. the method uses the theory of such functors developed in [ bt2, bt3 ], as well as some new ingredients in the theory of finite lattices.
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arxiv:1902.05422
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by harnessing the resonant nature of localized electromagnetic modes in a nanostructured silicon membrane, an all - dielectric metamaterial can act as nonlinear medium at optical telecommunications wavelengths. we show that such metamaterials provide extremely large optomechanical nonlinearities, operating at intensities of only a few { \ mu } w per unit cell and modulation frequencies as high as 152 mhz, thereby offering a path to fast, compact and energy efficient all - optical metadevices.
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arxiv:1508.00995
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we show that the discrete duals of the free orthogonal quantum groups have the haagerup property and the completely contractive approximation property. analogous results hold for the free unitary quantum groups and the quantum automorphism groups of finite - dimensional c * - algebras. the proof relies on the monoidal equivalence between free orthogonal quantum groups and suq ( 2 ) quantum groups, on the construction of a sufficient supply of bounded central functionals for suq ( 2 ) quantum groups, and on the free product techniques of ricard and xu. our results generalize previous work in the kac setting due to brannan on the haagerup property, and due to the second author on the ccap.
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arxiv:1306.6064
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the theoretical study of the optical properties of te - and tm - modes in a four - layer structure composed of the magneto - optical yttrium iron garnet guiding layer on a dielectric substrate covered by planar nanocomposite guiding multilayer is presented. the dispersion equation is obtained taking into account the bigyrotropic properties of yttrium - iron garnet, and an original algorithm for the guided modes identification is proposed. the dispersion spectra are analyzed and the energy flux distributions across the structure are calculated. the fourfold difference between the partial power fluxes within the waveguide layers is achieved in the wavelength range of 200 nm.
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arxiv:1703.05711
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we present a detailed study of the x - ray properties of the galaxy cluster abell 548b ( z = 0. 04 ), using xmm - newton data, and discuss the connection between the thermal properties and the presence of two extended relic radio sources located at the cluster periphery. we wish to analyze the dynamical state of the cluster and confirm the presence of a major merger. we will discuss the merger effects on the extended nonthermal emission. from the analysis of the temperature distribution and of the surface brightness profiles, we find evidence of a shock in the northern cluster region, just before the location of the two extended peripheral relics. from the optical analysis, we find that the cluster galaxies show a large $ \ sigma _ v $, and two components are needed to fit their velocity distribution. observational results were compared with a cluster simulation. the maps of gas temperature and density distribution from the simulation agree with the observational data in the case of a cluster merger nearly perpendicular to the plane of the sky and in the state after the maximum core collapse. we conclude that we are observing a galaxy cluster in a major merger phase, just after the maximum core collapse. the mass ratio is about 1 : 2, and the merger collision is nearly perpendicular to the plane of the sky. a shock is present in the northern cluster region, and it is very likely responsible for the electron reacceleration and the magnetic field amplification that will give cause the cluster relics. the relative position of the shock and the relics is strongly affected by projection effects.
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arxiv:0804.3607
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stimulated surface - and edge - emission were investigated for zno thin films grown epitaxially by pulsed laser deposition. the lasing threshold was 0. 32 mw / cm2 for surface pumping and 0. 5 mw / cm2 for edge pumping, which is significantly lower than thresholds observed previously. a modified variable stripe length method was used to measure the gain, which was 1369 cm - 1 for n - band emission. losses were measured using the shifting excitation spot method and values of 6. 2 cm - 1 and 6. 3 cm - 1 were found for the n - band and p - band, respectively. the measured gain and loss were the highest and lowest ( respectively ) ever reported for zno films.
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arxiv:1307.3636
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multi - agent coordination problems often require agents to exchange state information in order to reach some collective goal, such as agreement on a final state value. in some cases, it is feasible that opportunistic agents may deceptively report false state values for their own benefit, e. g., to claim a larger portion of shared resources. motivated by such cases, this paper presents a multi - agent coordination framework which disincentivizes opportunistic misreporting of state information. this paper focuses on multi - agent coordination problems that can be stated as nonlinear programs, with non - separable constraints coupling the agents. in this setting, an opportunistic agent may be tempted to skew the problem ' s constraints in its favor to reduce its local cost, and this is exactly the behavior we seek to disincentivize. the framework presented uses a primal - dual approach wherein the agents compute primal updates and a centralized cloud computer computes dual updates. all computations performed by the cloud are carried out in a way that enforces joint differential privacy, which adds noise in order to dilute any agent ' s influence upon the value of its cost function in the problem. we show that this dilution deters agents from intentionally misreporting their states to the cloud, and present bounds on the possible cost reduction an agent can attain through misreporting its state. this work extends our earlier work on incorporating ordinary differential privacy into multi - agent optimization, and we show that this work can be modified to provide a disincentivize for misreporting states to the cloud. numerical results are presented to demonstrate convergence of the optimization algorithm under joint differential privacy.
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arxiv:1509.08161
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i review the calculation of the next - to - leading order behavior of high - energy amplitudes in n = 4 sym and qcd using the operator expansion in wilson lines.
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arxiv:1004.0057
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theresults of numerical modelinghas based on the solution of navier - stokes equations for convection oftwo - layer system air - water are presented. the influence of thermocapillary and gravitational convection on the deformation and time averaged position of the interface of air - water system under sudden lateral heating of a square - section cavity are shown.
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arxiv:2203.02785
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raman spectroscopy is able to probe disorder in graphene through defect - activated peaks. it is of great interest to link these features to the nature of disorder. here we present a detailed analysis of the raman spectra of graphene containing different type of defects. we found that the intensity ratio of the d and d ' peak is maximum ( ~ 13 ) for sp3 - defects, it decreases for vacancy - like defects ( ~ 7 ) and reaches a minimum for boundaries in graphite ( ~ 3. 5 ).
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arxiv:1207.2058
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the unexpected emerging stability of a time - modulated magnetic guide, realized without external offset fields, is demonstrated. we found a steady periodic solution around which the nonlinear dynamics is linearized. to investigate the orbital stability of the guiding, a formal criterion based on the analysis of the eigenvalues of the monodromy matrix of the system dynamics is used. to circumvent the difficulty in finding an analytical expression for these eigenvalues, a lyapunov transformation of the system variables is proposed. from this transformation, an equation of state for the system parameters is derived, and it allows one to estimate an upper bound for the computed stability domains. in particular, we found a general expression for the threshold modulation frequency below which the guiding is unstable. using experimentally accessible parameters, the stable guiding of 87rb atoms is investigated.
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arxiv:1912.06841
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recently, there has been an increased interest in the study of the generation of low - energy cosmic rays ( crs ; < 1 tev ) in shocks situated on the surface of a protostar or along protostellar jets. these locally accelerated crs offer an attractive explanation for the high levels of non - thermal emission and ionisation rate, $ \ zeta $, observed close to these sources. the high $ \ zeta $ observed in some protostellar sources is generally attributed to shock - generated uv photons. the aim of this article is to show that when synchrotron emission and a high $ \ zeta $ are measured in the same spatial region, a locally shock - accelerated cr flux is sufficient to explain both phenomena. we assume that relativistic particles are accelerated according to the first - order fermi acceleration mechanism and compute $ \ zeta $ and the non - thermal emission at cm wavelengths. we then apply our model to the star - forming region omc - 2 fir 3 / fir 4. using a bayesian analysis, we constrain the parameters of the model and estimate the spectral indices of the non - thermal radio emission. we demonstrate that the local cr acceleration model makes it possible to simultaneously explain the synchrotron emission along the hops 370 jet within the fir 3 region and $ \ zeta $ observed near the fir 4 protocluster. our model constrains the magnetic field strength ( ~ 250 - 450 $ ~ \ mu $ g ), its turbulent component ( ~ 20 - 40 $ ~ \ mu $ g ), and the jet velocity in the shock reference frame for the three non - thermal sources of the hops 370 jet ( ~ 350 - 1000 km s $ ^ { - 1 } $ ). beyond the modelling of the omc - 2 fir 3 / fir 4 system, we show how the combination of continuum observations at cm wavelengths and molecular transitions is a powerful new tool for the analysis of star - forming regions : these two types of observations can be simultaneously interpreted by invoking only the presence of locally accelerated crs, without having to resort to shock - generated uv photons.
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arxiv:2103.08599
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in the wake of increasing numbers of attacks on radio communication systems, a range of techniques are being deployed to increase the security of these systems. one such technique is radio fingerprinting, in which the transmitter can be identified and authenticated by observing small hardware differences expressed in the signal. fingerprinting has been explored in particular in the defense of satellite systems, many of which are insecure and cannot be retrofitted with cryptographic security. in this paper, we evaluate the effectiveness of radio fingerprinting techniques under interference and jamming attacks, usually intended to deny service. by taking a pre - trained fingerprinting model and gathering a new dataset in which different levels of gaussian noise and tone jamming have been added to the legitimate signal, we assess the attacker power required in order to disrupt the transmitter fingerprint such that it can no longer be recognized. we compare this to gaussian jamming on the data portion of the signal, obtaining the remarkable result that transmitter fingerprints are still recognizable even in the presence of moderate levels of noise. through deeper analysis of the results, we conclude that it takes a similar amount of jamming power in order to disrupt the fingerprint as it does to jam the message contents itself, so it is safe to include a fingerprinting system to authenticate satellite communication without opening up the system to easier denial - of - service attacks.
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arxiv:2402.05042
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we present a new program implementation of the gaussian process regression adaptive density - guided approach [ j. chem. phys. 153 ( 2020 ) 064105 ] in the midascpp program. a number of technical and methodological improvements made allowed us to extend this approach towards calculations of larger molecular systems than those accessible previously and maintain the very high accuracy of constructed potential energy surfaces. we demonstrate the performance of this method on a test set of molecules of growing size and show that up to 80 % of single point calculations could be avoided introducing a root mean square deviation in fundamental excitations of about 3 cm $ ^ { - 1 } $. a much higher accuracy with errors below 1 cm $ ^ { - 1 } $ could be achieved with tighter convergence thresholds still reducing the number of single point computations by up to 68 %. we further support our findings with a detailed analysis of wall times measured while employing different electronic structure methods. our results demonstrate that gpr - adga is an effective tool, which could be applied for cost - efficient calculations of potential energy surfaces suitable for highly - accurate vibrational spectra simulations.
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arxiv:2303.15188
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we study the global existence of the singular nonlinear parabolic anderson model equation on $ 2 $ - dimensional tours $ \ mathbb { t } ^ 2 $. the method is based on paracontrolled distribution and renormalization. after split the original nonlinear parabolic anderson model equation into two simple equations, we prove the global well - posedness by some a priori estimates and smooth approximations. furthermore, we prove the uniqueness of the solution by using classical energy estimates.
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arxiv:2109.10423
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we study thermal effects on equations of state ( eos ) in isospin qcd, utilizing a quark - meson model coupled to a polyakov loop. the quark - meson model is analyzed at one - loop that is the minimal order to include quark substructure constraints on pions which condense at finite isospin density. in the previous study we showed that the quark - meson model at zero temperature produces the sound velocity peak and the negative trace anomaly in the domain between the chiral effective theory regime at low density and the perturbative qcd regime at high density, in reasonable agreement with lattice simulations. we now include thermal effects from quarks in the polyakov loop background and examine eos, especially the sound velocity and trace anomaly along isentropic trajectories. at large isospin density, there are three temperature windows ; ( i ) the pion condensed region with almost vanishing polyakov loops, ( ii ) the pion condensed region with finite polyakov loops, and ( iii ) the quark gas without pion condensates. in the domain ( i ), the gap associated with the pion condensate strongly quenches thermal excitations. as the system approaches the domain ( ii ), thermal quarks, which behave as non - relativistic particles, add energy density but little pressure, substantially reducing the sound velocity to the value less than the conformal value while increasing the trace anomaly toward the positive value. approaching the domain ( iii ), thermal quarks become more relativistic as pion condensates melt, increasing sound velocity toward the conformal limit. corrections from thermal pions are also briefly discussed.
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arxiv:2403.02538
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euclidean norm calculations arise frequently in scientific and engineering applications. several approximations for this norm with differing complexity and accuracy have been proposed in the literature. earlier approaches were based on minimizing the maximum error. recently, seol and cheun proposed an approximation based on minimizing the average error. in this paper, we first examine these approximations in detail, show that they fit into a single mathematical formulation, and compare their average and maximum errors. we then show that the maximum errors given by seol and cheun are significantly optimistic.
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arxiv:1008.4870
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observations suggest that some massive stars experience violent and eruptive mass loss associated with significant brightening that cannot be explained by hydrostatic stellar models. this event seemingly forms dense circumstellar matter ( csm ). the mechanism of eruptive mass loss has not been fully explained. we focus on the fact that the timescale of nuclear burning gets shorter than the dynamical timescale of the envelope a few years before core collapse for some massive stars. to reveal the properties of the eruptive mass loss, we investigate its relation to the energy injection at the bottom of the envelope supplied by nuclear burning taking place inside the core. in this study, we do not specify the actual mechanism for transporting energy from the site of nuclear burning to the bottom of the envelope. instead, we parameterize the amount of injected energy and the injection time and try to extract information on these parameters from comparisons with observations. we carried out 1 - d radiation hydrodynamical simulations for progenitors of red, yellow, and blue supergiants, and wolf - rayet stars. we calculated the evolution of the progenitors with a public stellar evolution code. we obtain the light curve associated with the eruption, the amount of ejected mass, and the csm distribution at the time of core - collapse. the energy injection at the bottom of the envelope of a massive star within a period shorter than the dynamical timescale of the envelope could reproduce some observed optical outbursts prior to the core - collapse and form the csm, which can power an interaction supernova ( sn ) classified as type iin.
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arxiv:1912.09738
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with artificial intelligence ( ai ) becoming relevant in various parts of everyday life, other technologies are already widely influenced by the new way of handling large amounts of data. although widespread already, ai has had only punctual influences on the cybersecurity field specifically. many techniques and technologies used by cybersecurity experts function through manual labor and barely draw on automation, e. g., logs are often reviewed manually by system admins for potentially malicious keywords. this work evaluates the use of a special type of ai called generative adversarial networks ( gans ) for log generation. more precisely, three different generative adversarial networks, seqgan, maligan, and cot, are reviewed in this research regarding their performance, focusing on generating new logs as a means of deceiving system admins for red teams. although static generators for fake logs have been around for a while, their produces are usually easy to reveal as such. using ai as an approach to this problem has not been widely researched. identified challenges consist of formatting, dates and times, and overall consistency. summing up the results, gans seem not to be a good fit for generating fake logs. their capability to detect fake logs, however, might be of use in practical scenarios.
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arxiv:2112.12006
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we study classes of right - angled coxeter groups with respect to the strong submodel relation of parabolic subgroup. we show that the class of all right - angled coxeter group is not smooth, and establish some general combinatorial criteria for such classes to be abstract elementary classes, for them to be finitary, and for them to be tame. we further prove two combinatorial conditions ensuring the strong rigidity of a right - angled coxeter group of arbitrary rank. the combination of these results translate into a machinery to build concrete examples of $ \ mathrm { aecs } $ satisfying given model - theoretic properties. we exhibit the power of our method constructing three concrete examples of finitary classes. we show that the first and third class are non - homogeneous, and that the last two are tame, uncountably categorical and axiomatizable by a single $ l _ { \ omega _ { 1 }, \ omega } $ - sentence. we also observe that the isomorphism relation of any countable complete first - order theory is $ \ kappa $ - borel reducible ( in the sense of generalized descriptive set theory ) to the isomorphism relation of the theory of right - angled coxeter groups whose coxeter graph is an infinite random graph.
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arxiv:1605.06003
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a brief overview is given of x - ray observations of old clusters. most x - ray sources in old open clusters are interacting binaries, formed via evolution of a primordial binary, and emitting x - rays because of magnetic activity ; however, a sizable fraction of the cluster sources is not well understood, including some of the most luminous ones. globular clusters appear to contain fewer magnetically active x - ray sources than expected if one scales from old open clusters by mass.
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arxiv:astro-ph/9907202
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in the realm of scientific computing, both julia and python have established themselves as powerful tools. within the context of high energy physics ( hep ) data analysis, python has been traditionally favored, yet there exists a compelling case for migrating legacy software to julia. this article focuses on language interoperability, specifically exploring how awkward array data structures can bridge the gap between julia and python. the talk offers insights into key considerations such as memory management, data buffer copies, and dependency handling. it delves into the performance enhancements achieved by invoking julia from python and vice versa, particularly for intensive array - oriented calculations involving large - scale, though not excessively dimensional, arrays of hep data. the advantages and challenges inherent in achieving interoperability between julia and python in the domain of scientific computing are discussed.
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arxiv:2404.18170
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in this paper we have obtained several new results concerning the x - boson, which is being considered recently as one of the main candidate of the dark matter particle content. the classical electrodynamics for the x - boson model was explored to understand its propagation in space - time. the field equations ( maxwell - type ) and the corresponding wave equations were obtained. they indicate the dispersion relations of both a massive and massless particles. these results can be interpreted as a photon and the x - boson ( with a mass of 17 mev ), respectively. the gauge symmetry and gauge transformations were discussed. a full model diagonalization was introduced to obtain a maxwell sector added up to a proca sector. after that, we have obtained the retarded green functions which yield the inhomogeneous solutions of the wave equations for the x - boson fields. we have applied this solution to the charge point motion, and we transformed the potential solution to a quadrature problem. in particular, as an example, we have analyzed the point charge in a straight line uniform motion, where the corresponding electromagnetic charge were calculated.
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arxiv:1802.10449
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it is expected since the early 1970s that tenuous dust rings are formed by grains ejected from the martian moons phobos and deimos by impacts of hypervelocity interplanetary projectiles. in this paper, we perform direct numerical integrations of a large number of dust particles originating from phobos and deimos. in the numerical simulations, the most relevant forces acting on dust are included : martian gravity with spherical harmonics up to 5th degree and 5th order, gravitational perturbations from the sun, phobos, and deimos, solar radiation pressure, as well as the poynting - robertson drag. in order to obtain the ring configuration, simulation results of various grain sizes ranging from submicron to 100 microns are averaged over a specified initial mass distribution of ejecta. we find that for the phobos ring grains smaller than about 2 microns are dominant ; while the deimos ring is dominated by dust in the size range of about 5 - 20 microns. the asymmetries, number densities and geometrical optical depths of the rings are quantified from simulations. the results are compared with the upper limits of the optical depth inferred from hubble observations. we compare to previous work and discuss the uncertainties of the models.
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arxiv:2201.02847
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birds - eye - view ( bev ) segmentation aims to establish a spatial mapping from the perspective view to the top view and estimate the semantic maps from monocular images. recent studies have encountered difficulties in view transformation due to the disruption of bev - agnostic features in image space. to tackle this issue, we propose a novel focusbev framework consisting of $ ( i ) $ a self - calibrated cross view transformation module to suppress the bev - agnostic image areas and focus on the bev - relevant areas in the view transformation stage, $ ( ii ) $ a plug - and - play ego - motion - based temporal fusion module to exploit the spatiotemporal structure consistency in bev space with a memory bank, and $ ( iii ) $ an occupancy - agnostic iou loss to mitigate both semantic and positional uncertainties. experimental evidence demonstrates that our approach achieves new state - of - the - art on two popular benchmarks, \ ie, 29. 2 \ % miou on nuscenes and 35. 2 \ % miou on argoverse.
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arxiv:2410.15932
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detecting human stress levels and emotional states with physiological body - worn sensors is a complex task, but one with many health - related benefits. robustness to sensor measurement noise and energy efficiency of low - power devices remain key challenges in stress detection. we propose selfcare, a fully wrist - based method for stress detection that employs context - aware selective sensor fusion that dynamically adapts based on data from the sensors. our method uses motion to determine the context of the system and learns to adjust the fused sensors accordingly, improving performance while maintaining energy efficiency. self - care obtains state - of - the - art performance across the publicly available wesad dataset, achieving 86. 34 % and 94. 12 % accuracy for the 3 - class and 2 - class classification problems, respectively. evaluation on real hardware shows that our approach achieves up to 2. 2x ( 3 - class ) and 2. 7x ( 2 - class ) energy efficiency compared to traditional sensor fusion.
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arxiv:2205.03974
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this paper argues that a combined treatment of probabilities, time and actions is essential for an appropriate logical account of the notion of probability ; and, based on this intuition, describes an expressive probabilistic temporal logic for reasoning about actions with uncertain outcomes. the logic is modal and higher - order : modalities annotated by actions are used to express possibility and necessity of propositions in the next states resulting from the actions, and a higher - order function is needed to express the probability operator. the proposed logic is shown to be an adequate extension of classical mathematical probability theory, and its expressiveness is illustrated through the formalization of the monty hall problem.
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arxiv:1603.07453
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it is well - known that in banach spaces with finite cotype, the $ r $ - bounded and $ \ gamma $ - bounded families of operators coincide. if in addition $ x $ is a banach lattice, then these notions can be expressed as square function estimates. it is also clear that $ r $ - boundedness implies $ \ gamma $ - boundedness. in this note we show that all other possible inclusions fail. furthermore, we will prove that $ r $ - boundedness is stable under taking adjoints if and only if the underlying space is $ k $ - convex.
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arxiv:1404.7328
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we study $ i = 3 / 2 $ elastic $ k \ pi $ scattering to born order using nonrelativistic quark wavefunctions in a constituent - exchange model. this channel is ideal for the study of nonresonant meson - meson scattering amplitudes since s - channel resonances do not contribute significantly. standard quark model parameters yield good agreement with the measured s - and p - wave phase shifts and with pcac calculations of the scattering length. the p - wave phase shift is especially interesting because it is nonzero solely due to $ su ( 3 ) _ f $ symmetry breaking effects, and is found to be in good agreement with experiment given conventional values for the strange and nonstrange constituent quark masses.
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arxiv:hep-ph/9207251
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today, many industrial processes are undergoing digital transformation, which often requires the integration of well - understood domain models and state - of - the - art machine learning technology in business processes. however, requirements elicitation and design decision making about when, where and how to embed various domain models and end - to - end machine learning techniques properly into a given business workflow requires further exploration. this paper aims to provide an overview of the requirements engineering process for machine learning applications in terms of cross domain collaborations. we first review the literature on requirements engineering for machine learning, and then go through the collaborative requirements analysis process step - by - step. an example case of industrial data - driven intelligence applications is also discussed in relation to the aforementioned steps.
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arxiv:2210.00859
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we show that the amoeba of a complex algebraic variety defined as the solutions to a generic system of $ n $ polynomials in $ n $ variables has a finite basis. in other words, it is the intersection of finitely many hypersurface amoebas. moreover, we give an upper bound of the size of the basis in terms of $ n $ and the mixed volume $ \ mu $ of the newton polytopes of the polynomial equations of the system. also, we give an upper bound of the degree of the basis elements in terms of $ \ mu $.
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arxiv:1404.3593
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we report on the recent results revealing the presence of geometric invariants in all the phenomena in which vacuum condensates appear and we show that aharonov - - anandan phase can be used to provide the evidence of phenomena like hawking and unruh effects and to test some behavior of quantum field theory in curved space. a very precise quantum thermometer can be also built by using geometric invariants.
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arxiv:1311.4491
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we derive analytical solutions for the uniaxial extension problem for the relaxed micromorphic continuum and other generalized continua. these solutions may help in the identification of material parameters of generalized continua which are able to disclose size - effects.
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arxiv:2107.09644
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hexagonal boron nitride sheets have been noted especially for their enhanced properties as substrates for sp2 carbon - based nanodevices. to evaluate whether such enhanced properties would remain under various realistic conditions, we investigate the structural and electronic properties of semiconducting carbon nanotubes on perfect and defective hexagonal boron nitride sheets under an external electric field as well as with a metal impurity, using density functional theory. we verify that the use of a perfect hexagonal boron nitride sheet as a substrate indeed improves the device performances of carbon nanotubes, compared with the use of conventional substrates such as sio2. we further show that the hexagonal boron nitride even with some defects can perform better performance as a substrate. our calculations, on the other hand, also suggest that some defective boron nitride layers with a monovacancy and a nickel impurity could bring about poor device behaviors since the imperfections impair electrical conductivity due to residual scattering under an applied electric field.
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arxiv:1502.02795
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we explore the ability of large language model ( llm ) - based agents to engage in subtle deception such as strategically phrasing and intentionally manipulating information to misguide and deceive other agents. this harmful behavior can be hard to detect, unlike blatant lying or unintentional hallucination. we build an adversarial testbed mimicking a legislative environment where two llms play opposing roles : a corporate * lobbyist * proposing amendments to bills that benefit a specific company while evading a * critic * trying to detect this deception. we use real - world legislative bills matched with potentially affected companies to ground these interactions. our results show that llm lobbyists initially exhibit limited deception against strong llm critics which can be further improved through simple verbal reinforcement, significantly enhancing their deceptive capabilities, and increasing deception rates by up to 40 points. this highlights the risk of autonomous agents manipulating other agents through seemingly neutral language to attain self - serving goals.
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arxiv:2405.04325
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in computed tomographic imaging, model based iterative reconstruction methods have generally shown better image quality than the more traditional, faster filtered backprojection technique. the cost we have to pay is that mbir is computationally expensive. in this work we train a 2. 5d deep learning ( dl ) network to mimic mbir quality image. the network is realized by a modified unet, and trained using clinical fbp and mbir image pairs. we achieve the quality of mbir images faster and with a much smaller computation cost. visually and in terms of noise power spectrum ( nps ), dl - mbir images have texture similar to that of mbir, with reduced noise power. image profile plots, nps plots, standard deviation, etc. suggest that the dl - mbir images result from a successful emulation of an mbir operator.
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arxiv:2309.13399
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we have performed a qcd next - to - leading order ( nlo ) calculation for deep inelastic scattering ( dis ) retaining the full parton and hadron mass dependencies. we find that the gluon initiated contributions to dis processes, such as charm production, are { \ it comparable } in magnitude ( { \ it i. e. }, $ 30 \ % $ to $ 100 \ % $ ) to the ` ` leading - order ' ' ( lo ) sea - quark processes. the ` ` slow - rescaling " prescription and the full nlo formalism are compared in a quantitative manner. the use of dis distributions and the inclusion of the charm mass via slow - rescaling are not sufficient to mimic the correct nlo physics. these results imply that previous analyses of charm production data to extract the strange and charm content of the nucleon, as well as the precise determination of standard model parameters based on these analyses ( such as the weinberg angle ), need to be reassessed.
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arxiv:hep-ph/9302305
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we use the ` ` map of elections ' ' approach of szufa et al. ( aamas - 2020 ) to analyze several well - known vote distributions. for each of them, we give an explicit formula or an efficient algorithm for computing its frequency matrix, which captures the probability that a given candidate appears in a given position in a sampled vote. we use these matrices to draw the ` ` skeleton map ' ' of distributions, evaluate its robustness, and analyze its properties. finally, we develop a general and unified framework for learning the distribution of real - world preferences using the frequency matrices of established vote distributions.
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arxiv:2205.07831
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in this work we look at the low lying nuclear structure of several n = z nuclei residing between the doubly magic nucei ^ { 40 } ca and ^ { 100 } sn. using large shell model codes we calculate and discuus the systematics of enegies. we show energy levels, b ( e2 ) ' s, static quadrupule moments and g factors. in all cases we compare the results of 2 different interactions which yield significanly different occupation numbers. we compare with the simplest versions of the rotational and vibrational models. by examinnig b ( e2 ) ' s and static quadrupole moments we make associations with collective models find that in the model space here considered, { } ^ { 88 } ru is oblate. the quadruple moment of ^ { 92 } pd is very small consistent with the vibrational model.
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arxiv:1307.5735
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we study how powerful algebraic discrete morse theory is when applied to hull resolutions. the main result describes all cases when the hull resolution of the edge ideal of the complement of a triangle - free graph can be made minimal using algebraic discrete morse theory.
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arxiv:1512.03045
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stationary, axisymmetric and slowly rotating vacuum spacetimes in the ho \ v { r } ava - lifshitz ( hl ) gravity are studied, and shown that, for any given spherical static vacuum solution of the hl theory ( of any model, including the ones with an additional u ( 1 ) symmetry ), there always exists a corresponding slowly rotating, stationary and axisymmetric vacuum solution, which reduces to the former, when the rotation is switched off. the rotation is universal and only implicitly depends on the models of the hl theory and their coupling constants through the spherical seed solution. as a result, all asymptotically flat slowly rotating vacuum solutions are asymptotically identical to the slowly rotating kerr solution. this is in contrast to the claim of barausse and sotiriou, phys. rev. lett. { \ bf 109 }, 181101 ( 2012 ), in which slowly rotating black holes were reported ( incorrectly ) not to exist in the infrared limit of the non - projectable hl theory.
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arxiv:1212.1876
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we study the influence of relativity on the chaotic properties and dynamical outcomes of an unstable triple system ; the pythagorean three - body problem. to this end, we extend the brutus n - body code to include post - newtonian pairwise terms up to 2. 5 order, and the first order taylor expansion to the einstein - infeld - hoffmann equations of motion. the degree to which our system is relativistic depends on the scaling of the total mass ( the unit size was 1 parsec ). using the brutus method of convergence, we test for time - reversibility in the conservative regime, and demonstrate that we are able to obtain definitive solutions to the relativistic three - body problem. it is also confirmed that the minimal required numerical accuracy for a successful time - reversibility test correlates with the amplification factor of an initial perturbation. when we take into account dissipative effects through gravitational wave emission, we find that the duration of the resonance, and the amount of exponential growth of small perturbations depend on the mass scaling. for a unit mass < = 10 msun, the system behavior is indistinguishable from the newtonian case, and the resonance always ends in a binary and one escaping body. for a mass scaling up to 1e7 msun, relativity gradually becomes more prominent, but the majority of the systems still dissolve. the first mergers start to appear for a mass of ~ 1e5 msun, and between 1e7 msun and 1e9 msun all systems end prematurely in a merger. these mergers are preceded by a gravitational wave driven in - spiral. for a mass scaling > = 1e9 msun, all systems result in a gravitational wave merger upon the first close encounter. relativistic three - body encounters thus provide an efficient pathway for resolving the final parsec problem. the onset of mergers at the characteristic mass scale of 1e7 msun potentially leaves an imprint in the mass function of supermassive black holes.
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arxiv:2109.07013
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we present an algorithm for the simultaneous measurement of a pulse time - of - arrival ( toa ) and dispersion measure ( dm ) from folded wideband pulsar data. we extend the prescription from taylor ( 1992 ) to accommodate a general two - dimensional template " portrait ", the alignment of which can be used to measure a pulse phase and dm. we show that there is a dedispersion reference frequency that removes the covariance between these two quantities, and note that the recovered pulse profile scaling amplitudes can provide useful information. we experiment with pulse modeling by using a gaussian - component scheme that allows for independent component evolution with frequency, a " fiducial component ", and the inclusion of scattering. we showcase the algorithm using our publicly available code on three years of wideband data from the bright millisecond pulsar j1824 - 2452a ( m28a ) from the green bank telescope, and a suite of monte carlo analyses validates the algorithm. by using a simple model portrait of m28a we obtain dm trends comparable to those measured by more standard methods, with improved toa and dm precisions by factors of a few. measurements from our algorithm will yield precisions at least as good as those from traditional techniques, but is prone to fewer systematic effects and is without ad hoc parameters. a broad application of this new method for dispersion measure tracking with modern large - bandwidth observing systems should improve the timing residuals for pulsar timing array experiments, like the north american nanohertz observatory for gravitational waves.
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arxiv:1402.1672
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extra neutral gauge bosons are a feature of many models of physics beyond the standard model ( bsm ) and their discovery could possibly be the first evidence for new physics. in this snowmass white paper we compare the discovery reach of the high energy hadron colliders considered by the snowmass study for a broad range of bsm models. it is expected that the lhc should be able to see evidence for a z ' arising from a large variety of bsm models up to a mass of ~ 5 tev when the lhc reaches its design energy and luminosity, and up to ~ 6 tev with the high luminosity upgrade. further into the future, the high energy lhc would substantially extend this reach to ~ 11 tev, while the ~ 100 tev vhe - lhc could see evidence for z ' ' s up to ~ 30 tev.
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arxiv:1309.1688
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machine learning techniques have enabled robots to learn narrow, yet complex tasks and also perform broad, yet simple skills with a wide variety of objects. however, learning a model that can both perform complex tasks and generalize to previously unseen objects and goals remains a significant challenge. we study this challenge in the context of " improvisational " tool use : a robot is presented with novel objects and a user - specified goal ( e. g., sweep some clutter into the dustpan ), and must figure out, using only raw image observations, how to accomplish the goal using the available objects as tools. we approach this problem by training a model with both a visual and physical understanding of multi - object interactions, and develop a sampling - based optimizer that can leverage these interactions to accomplish tasks. we do so by combining diverse demonstration data with self - supervised interaction data, aiming to leverage the interaction data to build generalizable models and the demonstration data to guide the model - based rl planner to solve complex tasks. our experiments show that our approach can solve a variety of complex tool use tasks from raw pixel inputs, outperforming both imitation learning and self - supervised learning individually. furthermore, we show that the robot can perceive and use novel objects as tools, including objects that are not conventional tools, while also choosing dynamically to use or not use tools depending on whether or not they are required.
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arxiv:1904.05538
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the notion of bohr chaos was introduced in [ 3, 4 ]. we answer a question raised in [ 3 ] of whether a non uniquely ergodic minimal system of positive topological entropy can be bohr chaotic. we also prove that all systems with the specification property are bohr chaotic, and by this line of thought give an independent proof ( and stengthening ) of theorem 1 of [ 3 ] for the case of invertible systems. in addition, we present an obstruction for bohr chaos : a system with fewer than a continuum of ergodic invariant probability measures cannot be bohr chaotic.
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arxiv:2109.04531
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this research presents a new parametric style transfer framework specifically designed for curve - based design sketches. in this research, traditional challenges faced by neural style transfer methods in handling binary sketch transformations are effectively addressed through the utilization of parametric shape - editing rules, efficient curve - to - pixel conversion techniques, and the fine - tuning of vgg19 on imagenet - sketch, enhancing its role as a feature pyramid network for precise style extraction. by harmonizing intuitive curve - based imagery with rule - based editing, this study holds the potential to significantly enhance design articulation and elevate the practice of style transfer within the realm of product design.
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arxiv:2401.08579
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writing desktop applications in javascript offers developers the opportunity to write cross - platform applications with cutting edge capabilities. however in doing so, they are potentially submitting their code to a number of unsanctioned modifications from malicious actors. electron is one such javascript application framework which facilitates this multi - platform out - the - box paradigm and is based upon the node. js javascript runtime - - - an increasingly popular server - side technology. in bringing this technology to the client - side environment, previously unrealized risks are exposed to users due to the powerful system programming interface that node. js exposes. in a concerted effort to highlight previously unexposed risks in these rapidly expanding frameworks, this paper presents the mayall framework, an extensible toolkit aimed at javascript security auditing and post - exploitation analysis. the paper also exposes fifteen highly popular electron applications and demonstrates that two thirds of applications were found to be using known vulnerable elements with high cvss scores. moreover, this paper discloses a wide - reaching and overlooked vulnerability within the electron framework which is a direct byproduct of shipping the runtime unaltered with each application, allowing malicious actors to modify source code and inject covert malware inside verified and signed applications without restriction. finally, a number of injection vectors are explored and appropriate remediations are proposed.
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arxiv:1811.05945
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dimension, as there exists a linear bijection between their elements. the concept of isomorphism extends to numerous branches of mathematics, including graph theory ( graph isomorphism ), topology ( homeomorphism ), and algebra ( group and ring isomorpisms ), among others. isomorphisms facilitate the classification of mathematical entities and enable the transfer of results and techniques between similar systems. bridging the gap between isomorphism and equality was one motivation for the development of category theory, as well as for homotopy type theory and univalent foundations. = = = geometry = = = in geometry, formally, two figures are equal if they contain exactly the same points. however, historically, geometric - equality has always been taken to be much broader. euclid and archimedes used " equal " ( ισος isos ) often referring to figures with the same area or those that could be cut and rearranged to form one another. for example, euclid stated the pythagorean theorem as " the square on the hypotenuse is equal to the squares on the sides, taken together " ; and archimedes said that " a circle is equal to the rectangle whose sides are the radius and half the circumference. " this notion persisted until adrien - marie legendre, who introduced the term " equivalent " to describe figures of equal area and restricted " equal " to what we now call " congruent " — the same shape and size, or if one has the same shape and size as the mirror image of the other. euclid ' s terminology continued in the work of david hilbert in his grundlagen der geometrie, who further refined euclid ' s ideas by introducing the notions of polygons being " divisibly equal " ( zerlegungsgleich ) if they can be cut into finitely many triangles which are congruent, and " equal in content " ( inhaltsgleichheit ) if one can add finitely many divisibly equal polygons to each such that the resulting polygons are divisibly equal. after the rise of set theory, around the 1960s, there was a push for a reform in mathematics education called new math, following andrey kolmogorov, who, in an effort to restructure russian geometry courses, proposed presenting geometry through the lens of transformations and set theory. since a figure was seen as a set of points, it could only
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https://en.wikipedia.org/wiki/Equality_(mathematics)
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we theoretically investigate twisted structures where each layer is composed of a strongly correlated material. in particular, we study a twisted t - j model of cuprate multilayers within the slave - boson mean field theory. this treatment encompasses the mott physics at small doping and self consistently generates d - wave pairing. furthermore, including the correct inter - layer tunneling form factor consistent with the symmetry of the cu $ d _ { x ^ 2 - y ^ 2 } $ orbital proves to be crucial for the phase diagram. we find spontaneous time reversal ( t ) breaking around twist angle of $ 45 ^ \ circ $, although only in a narrow window of twist angles. moreover, the gap obtained is small and the chern number vanishes, implying a non - topological superconductor. at smaller twist angles, driving an interlayer current however can lead to a gapped topological phase. the energy - phase relation of the interlayer josephson junction displays notable double - cooper - pair tunneling which dominates around $ 45 ^ o $. the twist angle dependence of the josephson critical current and the shapiro steps are consistent with recent experiments. utilizing the moir \ ' e structure as a probe of correlation physics, in particular of the pair density wave state, is discussed.
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arxiv:2109.08142
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new calculations to over ten million time steps have revealed a more complex diffusive behavior than previously reported, of a point particle on a square and triangular lattice randomly occupied by mirror or rotator scatterers. for the square lattice fully occupied by mirrors where extended closed particle orbits occur, anomalous diffusion was still found. however, for a not fully occupied lattice the super diffusion, first noticed by owczarek and prellberg for a particular concentration, obtains for all concentrations. for the square lattice occupied by rotators and the triangular lattice occupied by mirrors or rotators, an absence of diffusion ( trapping ) was found for all concentrations, except on critical lines, where anomalous diffusion ( extended closed orbits ) occurs and hyperscaling holds for all closed orbits with { \ em universal } exponents $ { \ displaystyle { d _ f = \ frac { 7 } { 4 } } } $ and $ { \ displaystyle { \ tau = \ frac { 15 } { 7 } } } $. only one point on these critical lines can be related to a corresponding percolation problem. the questions arise therefore whether the other critical points can be mapped onto a new percolation - like problem, and of the dynamical significance of hyperscaling.
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arxiv:comp-gas/9501003
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a pedagological introduction to effective field theory is presented.
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arxiv:physics/0003012
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