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2208.09778
|
The Development of a Labelled te reo M\=aori-English Bilingual Database for Language Technology
|
Te reo M\=aori (referred to as M\=aori), New Zealand's indigenous language, is under-resourced in language technology. M\=aori speakers are bilingual, where M\=aori is code-switched with English. Unfortunately, there are minimal resources available for M\=aori language technology, language detection and code-switch detection between M\=aori-English pair. Both English and M\=aori use Roman-derived orthography making rule-based systems for detecting language and code-switching restrictive. Most M\=aori language detection is done manually by language experts. This research builds a M\=aori-English bilingual database of 66,016,807 words with word-level language annotation. The New Zealand Parliament Hansard debates reports were used to build the database. The language labels are assigned using language-specific rules and expert manual annotations. Words with the same spelling, but different meanings, exist for M\=aori and English. These words could not be categorised as M\=aori or English based on word-level language rules. Hence, manual annotations were necessary. An analysis reporting the various aspects of the database such as metadata, year-wise analysis, frequently occurring words, sentence length and N-grams is also reported. The database developed here is a valuable tool for future language and speech technology development for Aotearoa New Zealand. The methodology followed to label the database can also be followed by other low-resourced language pairs.
|
[
"Computer Science Archive->cs.CL"
] | 2022-08-21T01:56:13Z |
0801.3415
|
Approximate and pseudo-amenability of various classes of Banach algebras
|
We continue the investigation of notions of approximate amenability that were introduced in work of the second and third authors. It is shown that every boundedly approximately contractible Banach algebra has a bounded approximate identity. Among our other results, it is shown that the Fourier algebra of the free group on two generators is not approximately amenable. Further examples are obtained of ${\ell}^1$-semigroup algebras which are approximately amenable but not amenable; using these, we show that bounded approximate amenability need not imply sequential approximate amenability. Results are also given for Segal subalgebras of $L^1(G)$, where $G$ is a locally compact group, and the algebras $PF_p(\Gamma)$ of $p$-pseudofunctions on a discrete group $\Gamma$ (of which the reduced $C^*$-algebra is a special case).
|
[
"Mathematics Archive->math.FA"
] | 2008-01-22T20:50:02Z |
2308.16068
|
Ruliology: Linking Computation, Observers and Physical Law
|
Stephen Wolfram has recently outlined an unorthodox, multicomputational approach to fundamental theory, encompassing not only physics but also mathematics in a structure he calls The Ruliad, understood to be the entangled limit of all possible computations. In this framework, physical laws arise from the the sampling of the Ruliad by observers (including us). This naturally leads to several conceptual issues, such as what kind of object is the Ruliad? What is the nature of the observers carrying out the sampling, and how do they relate to the Ruliad itself? What is the precise nature of the sampling? This paper provides a philosophical examination of these questions, and other related foundational issues, including the identification of a limitation that must face any attempt to describe or model reality in such a way that the modeller-observers are included
|
[
"Physics Archive->physics->physics.hist-ph"
] | 2023-08-30T14:45:22Z |
2304.03795
|
Constraints on the Inner Regions of Lensing Galaxies from Central Images using a Recent AGN Offset Distribution
|
In gravitational lensing, central images in quads can serve as a powerful probe of the inner regions of lens galaxies. The presence of an offset central supermassive black hole (SMBH) has the potential to distort the time-delay surface in a way such that 3 central images form: a strongly de-magnified image near the SMBH, and two less de-magnified (and potentially observable) images at a central maximum and saddle point. Using a quad lens macro model, we simulate the constraints that could be placed on various lens galaxy parameters based on their central images probability of detection or non-detection. Informed by a recent low-redshift distribution of off-nucleus AGN, we utilize Bayesian inference to constrain the mean SMBH off-nucleus distance and galactic core radius for a sample of 6 quads. In general, we find that a detection of the central image in any quad would favor larger SMBH off-nucleus distances and galaxy core sizes. Assuming a linear relationship between core radii and velocity dispersion $r_c = b\sigma$, these results similarly imply strong constraints on $b$, where the likely case of a central image non-detection in each quad constraining $b$ to $3.11^{+2.72}_{-2.26} \times 10^{-4}$ kpc km$^{-1}$ s. Our results show that tight constraints on lens galaxy parameters can be made regardless of a detection or non-detection of a central image. Therefore, we recommend observational searches for the central image, possibly using our suggested novel detection technique in UV filters, to formalize stronger constraints on lens galaxy parameters.
|
[
"Physics Archive->astro-ph->astro-ph.GA"
] | 2023-04-07T18:00:17Z |
1504.04450
|
Degenerate SDE with H\"older-Dini Drift and Non-Lipschitz Noise Coefficient
|
The existence-uniqueness and stability of strong solutions are proved for a class of degenerate stochastic differential equations, where the noise coeffcicient might be non-Lipschitz, and the drift is locally Dini continuous in the component with noise (i.e. the second component) and locally H\"older-Dini continuous of order $\ff 2 3$ in the first component. Moreover, the weak uniqueness is proved under weaker conditions on the noise coefficient. Furthermore, if the noise coefficient is $C^{1+\vv}$ for some $\vv>0$ and the drift is H\"older continuous of order $\aa\in (\ff 2 3,1)$ in the first component and order $\bb\in(0,1) $ in the second, the solution forms a $C^1$-stochastic diffeormorphism flow. To prove these results, we present some new characterizations of H\"older-Dini space by using the heat semigroup and slowly varying functions.
|
[
"Mathematics Archive->math.PR"
] | 2015-04-17T06:21:21Z |
1507.06866
|
Compressed Data Structures for Dynamic Sequences
|
We consider the problem of storing a dynamic string $S$ over an alphabet $\Sigma=\{\,1,\ldots,\sigma\,\}$ in compressed form. Our representation supports insertions and deletions of symbols and answers three fundamental queries: $\mathrm{access}(i,S)$ returns the $i$-th symbol in $S$, $\mathrm{rank}_a(i,S)$ counts how many times a symbol $a$ occurs among the first $i$ positions in $S$, and $\mathrm{select}_a(i,S)$ finds the position where a symbol $a$ occurs for the $i$-th time. We present the first fully-dynamic data structure for arbitrarily large alphabets that achieves optimal query times for all three operations and supports updates with worst-case time guarantees. Ours is also the first fully-dynamic data structure that needs only $nH_k+o(n\log\sigma)$ bits, where $H_k$ is the $k$-th order entropy and $n$ is the string length. Moreover our representation supports extraction of a substring $S[i..i+\ell]$ in optimal $O(\log n/\log\log n + \ell/\log_{\sigma}n)$ time.
|
[
"Computer Science Archive->cs.DS"
] | 2015-07-24T14:57:18Z |
1305.4594
|
Quench Dynamics in Bose condensates in the Presence of a Bath: Theory and Experiment
|
In this paper we study the transient dynamics of a Bose superfluid subsequent to an interaction quench. Essential for equilibration is a source of dissipation which we include following the approach of Caldeira and Leggett. Here we solve the equations of motion exactly by integrating out an environmental bath. We thereby derive precisely the time dependent density correlation functions with the appropriate analytic and asymptotic properties. The resulting structure factor exhibits the expected damping and thereby differs from that of strict Bogoliubov theory. These damped sound modes, which reflect the physics beyond mean field approaches, are characterized and the structure factors are found to compare favorably with experiment.
|
[
"Physics Archive->cond-mat->cond-mat.quant-gas"
] | 2013-05-20T18:08:40Z |
1304.1611
|
Pb0.95La0.05Zr0.54Ti0.46O3 Thin Films For Photovoltaic Applications
|
Ferroelectrics have shown potential as a promising alternative material for future photovoltaic applications. Observance of high open circuit voltages in ferroelectric thin films, have generated considerable interest in the field of ferroelectric photovoltaic in recent years. The field of ferroelectric photovoltaic is evolving and not yet completely understood compared to the semiconductor based photovoltaic technology. This dissertation investigates photovoltaic characteristics of ferroelectric films in an attempt to further the understanding of ferroelectric photovoltaic. This dissertation presents photovoltaic properties of ferroelectric Pb0.95La0.05Zr0.54Ti0.46O3 thin films. The films were fabricated by solution based method and spin coating technique. The post annealing process on these films was optimized to achieve the desired ferroelectric and dielectric properties. A measurement setup was established to study the PV characteristic of the devices. Dependence of current-voltage (I-V) behavior of the cells on parameters such as electrical poling, annealing temperature, nature of top electrodes, and intensity of illumination, were investigated. The photovoltaic response was shown to improve by using electrodes with low work functions. An electric circuit model was developed to simulate the behavior of a single ferroelectric photovoltaic cell and the dependence of open circuit voltage (Voc) and short circuit current (Isc) on light intensity.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2013-04-05T04:19:53Z |
1603.06097
|
Laser-Induced Spallation of Microsphere Monolayers
|
The detachment of a semi-ordered monolayer of polystyrene microspheres adhered to an aluminum-coated glass substrate is studied using a laser-induced spallation technique. The microsphere-substrate adhesion force is estimated from substrate surface displacement measurements obtained using optical interferometry, and a rigid-body model that accounts for the inertia of the microspheres. The estimated adhesion force is compared with estimates obtained from interferometric measurement of the out-of-plane microsphere contact resonance. Reasonable agreement is found between the two experiments. Scanning electron microscope images of detached monolayer regions reveal a unique morphology, namely, partially detached monolayer flakes composed of single hexagonal close packed crystalline domains. This work contributes to an improved understanding of microsphere adhesion and demonstrates a unique monolayer delamination morphology.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall",
"Physics Archive->physics->physics.optics"
] | 2016-03-19T14:09:48Z |
0806.2008
|
Generalized proportional conflict redistribution rule applied to Sonar imagery and Radar targets classification
|
In this chapter, we present two applications in information fusion in order to evaluate the generalized proportional conflict redistribution rule presented in the chapter \cite{Martin06a}. Most of the time the combination rules are evaluated only on simple examples. We study here different combination rules and compare them in terms of decision on real data. Indeed, in real applications, we need a reliable decision and it is the final results that matter. Two applications are presented here: a fusion of human experts opinions on the kind of underwater sediments depict on sonar image and a classifier fusion for radar targets recognition.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.CV"
] | 2008-06-12T06:47:26Z |
1310.3617
|
Asteroid spin-axis longitudes from the Lowell Observatory database
|
By analyzing brightness variation with ecliptic longitude and using the Lowell Observatory photometric database, we estimate spin-axis longitudes for more than 350 000 asteroids. Hitherto, spin-axis longitude estimates have been made for fewer than 200 asteroids. We investigate longitude distributions in different dynamical groups and asteroid families. We show that asteroid spin-axis longitudes are not isotropically distributed as previously considered. We find that the spin-axis longitude distribution for main-belt asteroids is clearly non-random, with an excess of longitudes from the interval 30{\deg}-110{\deg} and a paucity between 120{\deg}-180{\deg}. The explanation of the non-isotropic distribution is unknown at this point. Further studies have to be conducted to determine if the shape of the distribution can be explained by observational bias, selection effects, a real physical process or other mechanism.
|
[
"Physics Archive->astro-ph->astro-ph.EP"
] | 2013-10-14T10:16:34Z |
2307.09875
|
Predictions of the ratio and asymmetry probes of the invisible $Z$-boson decay
|
Higher-order predictions through the combined accuracy including next-to-leading order (NLO) electroweak (EW) and next-to-NLO (NNLO) quantum chromodynamics (QCD) corrections in underlying perturbation theories are presented thoroughly for the invisible decay of the $Z$ boson into neutrino pair relative to its decay into charged-lepton pair (leptonic decay). The combined NNLO QCD+NLO EW predictions are achieved based on the fully-differential calculations of cross sections of both the invisible and leptonic processes in proton-proton ($pp$) collisions at 13 TeV center-of-mass energy. Differential distributions of cross-section ratios of the invisible process to the leptonic process are presented as a function of the transverse momentum of the $Z$ boson $p^{Z}_{\rm{T}}$. For the first time, the predictions for differential distributions of cross-section asymmetries between the invisible process and the leptonic process are presented in bins of the $p^{Z}_{\rm{T}}$. The cross-section ratio and asymmetry distributions, which are referred to as the invisible probes, are considered to be important for controlling the invisible process by the leptonic process of the $Z$ boson and probing deviation from the Standard Model (SM) for new-physics searches. The predictions are extensively presented beyond the $Z$-boson mass resonance region to assess the potential of the invisible ratio and asymmetry probes for new-phenomena searches in high-invariant mass region of the lepton-pair final states. Various tests with threshold requirements of transverse momenta of neutrino pair and leptons are performed to assess the impact on the combined predictions. The invisible ratio and asymmetry probes are proposed to be important probes for indirect searches of new-physics scenarios.
|
[
"Physics Archive->hep->hep-ph"
] | 2023-07-19T10:07:51Z |
hep-th/0002079
|
The $\nu \nu \gamma$ Amplitude in an External Homogeneous Electromagnetic Field
|
Neutrino-photon interactions in the presence of an external homogeneous constant electromagnetic field are studied. The $\nu \nu \gamma $ amplitude is calculated in an electromagnetic field of the general type, when the two field invariants are nonzero.
|
[
"Physics Archive->hep->hep-th"
] | 2000-02-10T09:05:30Z |
2305.17001
|
Awesome SOSS: Transmission Spectroscopy of WASP-96b with NIRISS/SOSS
|
The future is now - after its long-awaited launch in December 2021, JWST began science operations in July 2022 and is already revolutionizing exoplanet astronomy. The Early Release Observations (ERO) program was designed to provide the first images and spectra from JWST, covering a multitude of science cases and using multiple modes of each on-board instrument. Here, we present transmission spectroscopy observations of the hot-Saturn WASP-96b with the Single Object Slitless Spectroscopy (SOSS) mode of the Near Infrared Imager and Slitless Spectrograph, observed as part of the ERO program. As the SOSS mode presents some unique data reduction challenges, we provide an in-depth walk-through of the major steps necessary for the reduction of SOSS data: including background subtraction, correction of 1/f noise, and treatment of the trace order overlap. We furthermore offer potential routes to correct for field star contamination, which can occur due to the SOSS mode's slitless nature. By comparing our extracted transmission spectrum with grids of atmosphere models, we find an atmosphere metallicity between 1x and 5x solar, and a solar carbon-to-oxygen ratio. Moreover, our models indicate that no grey cloud deck is required to fit WASP-96b's transmission spectrum, but find evidence for a slope shortward of 0.9$\mu$m, which could either be caused by enhanced Rayleigh scattering or the red wing of a pressure-broadened Na feature. Our work demonstrates the unique capabilities of the SOSS mode for exoplanet transmission spectroscopy and presents a step-by-step reduction guide for this new and exciting instrument.
|
[
"Physics Archive->astro-ph->astro-ph.EP"
] | 2023-05-26T14:59:31Z |
hep-th/9811012
|
A geometrical interpretation of parity violation in gravity with torsion
|
In a space-time with torsion, the action for the gravitational field can be extended with a parity-violating piece. We show how to obtain such a piece from geometry itself, by suitably modifying the affine connection so as to include a pseudo-tensorial part. A consistent method is thus suggested for incorporating parity-violation in the Lagrangians of all matter fields with spin in a space-time background with torsion.
|
[
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-ph",
"Physics Archive->hep->hep-th"
] | 1998-11-02T12:18:01Z |
1004.3852
|
Seesaw Neutrino Signals at the Large Hadron Collider
|
We discuss the scenario with gauge singlet fermions (right-handed neutrinos) accessible at the energy of the Large Hadron Collider. The singlet fermions generate tiny neutrino masses via the seesaw mechanism and also have sizable couplings to the standard-model particles. We demonstrate that these two facts, which are naively not satisfied simultaneously, are reconciled in the five-dimensional framework in various fashions, which make the seesaw mechanism observable. The collider signal of tri-lepton final states with transverse missing energy is investigated for two explicit examples of the observable seesaw, taking account of three types of neutrino mass spectrum and the constraint from lepton flavor violation. We find by showing the significance of signal discovery that the collider experiment has a potential to find signals of extra dimensions and the origin of small neutrino masses.
|
[
"Physics Archive->hep->hep-ph"
] | 2010-04-22T07:23:17Z |
2107.01395
|
Polynomial generators of msu*[1/2] related to classifying maps of certain formal group laws
|
This paper presents a commutative complex-oriented cohomology theory that realizes the Buchstaber formal group law localized away from 2. Also, the restriction of the classifying map of FB on special unitary cobordism ring localized away from 2 defines a four parameter genus, studied by Hoehn and Totaro.
|
[
"Mathematics Archive->math.AT"
] | 2021-07-03T10:07:55Z |
1908.09674
|
Quadratic, Higgs and hilltop potentials in the Palatini gravity
|
In this work, we study inflation with the non-minimally coupled quadratic, Standard Model (SM) Higgs and hilltop potentials through $\xi \phi^2R$ term in the Palatini gravity. We first analyze observational parameters of Palatini quadratic potential as functions of $\xi$ for high-$N$ scenario and low-$N$ scenario. In addition to this, taking into account inflaton $\phi$ has a non-zero vacuum expectation value $v$ afterwards inflation, we display observational parameters of well-known symmetry-breaking potentials type of Higgs potential and its generalizations which are hilltop potentials in the Palatini formalism for high-$N$ scenario and low-$N$ scenario. We calculate inflationary parameters of Palatini Higgs potential as functions of $v$ for different $\xi$ values where inflaton values both $\phi>v$ and $\phi<v$ during inflation as well as we show that observational parameters of Palatini Higgs potential in the induced gravity limit for high-$N$ scenario. On the other hand, we illustrate different from the Higgs potential the effect of $\xi$ on hilltop potentials which can agree with the observations for inflaton value solely $\phi<v$ and $\xi$, $v\ll1$ for both two scenarios, which we mentioned above. For each considered potentials, we also display $n_s-r$ values fit the current data given by the Keck Array/BICEP2 and Planck collaborations.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->hep->hep-ph"
] | 2019-08-26T13:35:55Z |
0803.3246
|
A secular theory of coplanar, non-resonant planetary system
|
We present the secular theory of coplanar $N$-planet system, in the absence of mean motion resonances between the planets. This theory relies on the averaging of a perturbation to the two-body problem over the mean longitudes. We expand the perturbing Hamiltonian in Taylor series with respect to the ratios of semi-major axes which are considered as small parameters, without direct restrictions on the eccentricities. Next, we average out the resulting series term by term. This is possible thanks to a particular but in fact quite elementary choice of the integration variables. It makes it possible to avoid Fourier expansions of the perturbing Hamiltonian. We derive high order expansions of the averaged secular Hamiltonian (here, up to the order of 24) with respect to the semi-major axes ratio. The resulting secular theory is a generalization of the octupole theory. The analytical results are compared with the results of numerical (i.e., practically exact) averaging. We estimate the convergence radius of the derived expansions, and we propose a further improvement of the algorithm. As a particular application of the method, we consider the secular dynamics of three-planet coplanar system. We focus on stationary solutions in the HD 37124 planetary system.
|
[
"Physics Archive->astro-ph"
] | 2008-03-22T14:36:08Z |
1609.09300
|
Combining BRITE and ground-based photometry for the Beta Cephei star Nu Eridani: impact on photometric pulsation mode identification and detection of several g modes
|
We report a simultaneous ground and space-based photometric study of the Beta Cephei star Nu Eridani. Half a year of observations have been obtained by four of the five satellites constituting BRITE-Constellation, supplemented with ground-based photoelectric photometry. We show that carefully combining the two data sets virtually eliminates the aliasing problem that often hampers time-series analyses. We detect 40 periodic signals intrinsic to the star in the light curves. Despite a lower detection limit we do not recover all the pressure and mixed modes previously reported in the literature, but we newly detect six additional gravity modes. This behaviour is a consequence of temporal changes in the pulsation amplitudes that we also detected for some of the p modes. We point out that the dependence of theoretically predicted pulsation amplitude on wavelength is steeper in visual passbands than those observationally measured, to the extent that the three dominant pulsation modes of Nu Eridani would be incorrectly identified using data in optical filters only. We discuss possible reasons for this discrepancy.
|
[
"Physics Archive->astro-ph->astro-ph.SR"
] | 2016-09-29T11:38:01Z |
cond-mat/0210112
|
Orientational Ordering in Monolayers of Ortho-Para Hydrogen
|
We discuss orientational ordering in monolayers of solid hydrogen in view of recent experimental findings in NMR studies of (\QTR{it}{ortho)}$_{c}$-(\QTR{it}{para)}$_{1-c}$-hydrogen mixtures on boron nitride substrate. Analysis of the temperature-concentration behavior for the observed NMR frequency splitting is given on the basis of a two-dimension ($J=1)_{c}$-($J=0)_{1-c}$-rotor model with the quadrupolar coupling constant $\Gamma_{0}=0.50\pm 0.03$ $K$ and the crystalline field amplitude $V_{0}=0.70\pm 0.10$ $K$ derived from experiment. The two distinct para-rotational (PR) short-range ordered structures are described in terms of the local alignment and orientation of the polar principal axis, and are shown to be due to the interplay between the positive and negative crystalline fields. It is shown that the observed below the 2D site percolation threshold $c_{p}=0.72$ local structures are rather different from the ferromagnetic-type PR ordering suggested earlier by Harris and Berlinsky.
|
[
"Physics Archive->cond-mat->cond-mat.dis-nn"
] | 2002-10-04T19:01:58Z |
physics/0703088
|
Optical scatter imaging using digital Fourier microscopy
|
An approach reported recently by Alexandrov et al. on optical scatter imaging, termed digital Fourier microscopy (DFM), represents an adaptation of digital Fourier holography to selective imaging of biological matter. Holographic mode of recording of the sample optical scatter enables reconstruction of the sample image. Form-factor of the sample constituents provides a basis for discrimination of these constituents implemented via flexible digital Fourier filtering at the post processing stage. Like in the dark-field microscopy, the DFM image contrast appears to improve due to the suppressed optical scatter from extended sample structures. In this paper, we present theoretical and experimental study of DFM using biological phantom that contains polymorphic scatterers.
|
[
"Physics Archive->physics->physics.optics"
] | 2007-03-07T22:15:41Z |
2202.02781
|
Topological Corner States in Graphene by Bulk and Edge Engineering
|
Two-dimensional higher-order topology is usually studied in (nearly) particle-hole symmetric models, so that an edge gap can be opened within the bulk one. But more often deviates the edge anticrossing even into the bulk, where corner states are difficult to pinpoint. We address this problem in a graphene-based $\mathbb{Z}_2$ topological insulator with spin-orbit coupling and in-plane magnetization both originating from substrates through a Slater-Koster multi-orbital model. The gapless helical edge modes cross inside the bulk, where is also located the magnetization-induced edge gap. After demonstrating its second-order nontriviality in bulk topology by a series of evidence, we show that a difference in bulk-edge onsite energy can adiabatically tune the position of the crossing/anticrossing of the edge modes to be inside the bulk gap. This can help unambiguously identify two pairs of topological corner states with nonvanishing energy degeneracy for a rhombic flake. We further find that the obtuse-angle pair is more stable than the acute-angle one. These results not only suggest an accessible way to "find" topological corner states, but also provide a higher-order topological version of "bulk-boundary correspondence".
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall"
] | 2022-02-06T14:34:58Z |
cond-mat/0701377
|
An analytic expression for the electronic correlation term of the kinetic functional
|
We propose an analytic formula for the non-local Fisher information functional, or electronic kinetic correlation term, appearing in the expression of the kinetic density functional. Such an explicit formula is constructed on the basis of well-founded physical arguments and a rigorous mathematical prescription.
|
[
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | 2007-01-16T14:17:04Z |
1310.5659
|
Minimal Liouville Gravity correlation numbers from Douglas string equation
|
We continue the study of $(q,p)$ Minimal Liouville Gravity with the help of Douglas string equation. We generalize the results of \cite{Moore:1991ir}, \cite{Belavin:2008kv}, where Lee-Yang series $(2,2s+1)$ was studied, to $(3,3s+p_0)$ Minimal Liouville Gravity, where $p_0=1,2$. We demonstrate that there exist such coordinates $\tau_{m,n}$ on the space of the perturbed Minimal Liouville Gravity theories, in which the partition function of the theory is determined by the Douglas string equation. The coordinates $\tau_{m,n}$ are related in a non-linear fashion to the natural coupling constants $\lambda_{m,n}$ of the perturbations of Minimal Lioville Gravity by the physical operators $O_{m,n}$. We find this relation from the requirement that the correlation numbers in Minimal Liouville Gravity must satisfy the conformal and fusion selection rules. After fixing this relation we compute three- and four-point correlation numbers when they are not zero. The results are in agreement with the direct calculations in Minimal Liouville Gravity available in the literature \cite{Goulian:1990qr}, \cite{Zamolodchikov:2005sj}, \cite{Belavin:2006ex}.
|
[
"Physics Archive->hep->hep-th"
] | 2013-10-21T17:50:21Z |
1710.03463
|
Learning to Generalize: Meta-Learning for Domain Generalization
|
Domain shift refers to the well known problem that a model trained in one source domain performs poorly when applied to a target domain with different statistics. {Domain Generalization} (DG) techniques attempt to alleviate this issue by producing models which by design generalize well to novel testing domains. We propose a novel {meta-learning} method for domain generalization. Rather than designing a specific model that is robust to domain shift as in most previous DG work, we propose a model agnostic training procedure for DG. Our algorithm simulates train/test domain shift during training by synthesizing virtual testing domains within each mini-batch. The meta-optimization objective requires that steps to improve training domain performance should also improve testing domain performance. This meta-learning procedure trains models with good generalization ability to novel domains. We evaluate our method and achieve state of the art results on a recent cross-domain image classification benchmark, as well demonstrating its potential on two classic reinforcement learning tasks.
|
[
"Computer Science Archive->cs.LG"
] | 2017-10-10T09:15:16Z |
1609.08281
|
An Efficient Method for Robust Projection Matrix Design
|
Our objective is to efficiently design a robust projection matrix $\Phi$ for the Compressive Sensing (CS) systems when applied to the signals that are not exactly sparse. The optimal projection matrix is obtained by mainly minimizing the average coherence of the equivalent dictionary. In order to drop the requirement of the sparse representation error (SRE) for a set of training data as in [15] [16], we introduce a novel penalty function independent of a particular SRE matrix. Without requiring of training data, we can efficiently design the robust projection matrix and apply it for most of CS systems, like a CS system for image processing with a conventional wavelet dictionary in which the SRE matrix is generally not available. Simulation results demonstrate the efficiency and effectiveness of the proposed approach compared with the state-of-the-art methods. In addition, we experimentally demonstrate with natural images that under similar compression rate, a CS system with a learned dictionary in high dimensions outperforms the one in low dimensions in terms of reconstruction accuracy. This together with the fact that our proposed method can efficiently work in high dimension suggests that a CS system can be potentially implemented beyond the small patches in sparsity-based image processing.
|
[
"Computer Science Archive->cs.LG"
] | 2016-09-27T06:59:11Z |
1801.04571
|
VLBI imaging of M81* at 3.4 mm with source-frequency phase-referencing
|
We report on the first VLBI image of the M81 nucleus (M81*) at a wavelength of 3.4 mm, obtained with the source-frequency phase-referencing (SFPR) technique. Thanks to the SFPR calibration, the coherent integration time could be eventually increased by more than an order of magnitude, which enabled the detection of fringes at the level of 45 mJy beam-1 with a dynamic range higher than 130:1. This paves the way toward future mm/sub-mm VLBI observations of weaker sources. From the analysis of the M81* visibilities, a core size of ~50 uas at 3.4 mm was estimated. This follows the power-law relationship with wavelength lambda^0.88, reported previously at lower frequencies. These results constrain the core size (at 3.4 mm) to a minimum of ~80 Schwarzschild radii of M81*.
|
[
"Physics Archive->astro-ph->astro-ph.IM"
] | 2018-01-14T15:11:17Z |
1304.7830
|
Stoichiometry control of the electronic properties of the LaAlO_3/SrTiO_3 heterointerface
|
We investigate the effect of the laser parameters of pulsed laser deposition on the film stoichiometry and electronic properties of LaAlO_3/SrTiO_3 (001) heterostructures. The La/Al ratio in the LaAlO_3 films was varied over a wide range from 0.88 to 1.15, and was found to have a strong effect on the interface conductivity. In particular, the carrier density is modulated over more than two orders of magnitude. The film lattice expansion, caused by cation vacancies, is found to be the important functional parameter. These results can be understood to arise from the variations in the electrostatic boundary conditions, and their resolution, with stoichiometry.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2013-04-30T01:31:06Z |
hep-ph/9707317
|
Challenges for Inverted Hybrid Inflation
|
Inverted hybrid inflation (in which the inflaton field slowly rolls away from the origin, giving a spectral index $n\lsim 1$) is an appealing variant of the more usually studied hybrid model. Analysing the model alongside the ordinary hybrid case, we show that, in order to provide the correct density perturbations consistent with the COBE measurements, the dimensionless coupling constants of the inverted hybrid potential must be very small indeed. For example, the quartic coupling in a typical such potential is found to be $\lsim 10^{-12}$. A supersymmetric model of inverted hybrid inflation, which does not involve the troublesome quartic coupling is found to lead to a potential which is unbounded from below.
|
[
"Physics Archive->astro-ph",
"Physics Archive->hep->hep-ph"
] | 1997-07-11T07:51:50Z |
2203.07017
|
Bragg-diffraction-induced imperfections of the signal in retroreflective atom interferometers
|
We present a detailed study of the effects of imperfect atom-optical manipulation in Bragg-based light-pulse atom interferometers. Off-resonant higher-order diffraction leads to population loss, spurious interferometer paths, and diffraction phases. In a path-dependent formalism, we study numerically various effects and analyze the interference signal caused by an external phase or gravity. We compare first-order single and double Bragg diffraction in retroreflective setups. In double Bragg diffraction, phase imperfections lead to a beating due to three-path interference. Some effects of diffraction phases can be avoided by adding the population of the outer exit ports of double diffraction.
|
[
"Physics Archive->physics->physics.atom-ph",
"Physics Archive->quant-ph"
] | 2022-03-14T11:56:35Z |
2207.04670
|
Experimental realization of a high precision tunable hexagonal optical lattice
|
Hexagonal optical lattices offer a tunable platform to study exotic orbital physics in solid state materials. Here, we present a versatile high-precision scheme to implement a hexagonal optical lattice potential, which is engineered by overlapping two independent triangular optical sublattices generated by laser beams with slightly different wavelengths around 1064 nm. This enables us to precisely control the detailed structure of the hexagonal lattice by adjusting the relative position and the relative lattice depth of the two triangular optical sublattices. Taking advantage of the sensitive dependence of the second Bloch band on small lattice deformations, we propose a strategy to optimize the optical lattice geometry with an extremely high precision. This method can also be extended to other lattice configurations involving more than two sublattices. Our work provides the experimental requirements in the search for novel orbital physics of ultracold atoms, for example, in the flat $p$-band of the hexagonal optical lattice.
|
[
"Physics Archive->cond-mat->cond-mat.quant-gas"
] | 2022-07-11T07:25:38Z |
math/0611153
|
Decay of correlations for slowly mixing flows
|
We show that polynomial decay of correlations is prevalent for a class of nonuniformly hyperbolic flows. These flows are the continuous time analogue of a class of nonuniformly hyperbolic diffeomorphisms for which Young proved polynomial decay of correlations. Roughly speaking, in situations where the decay rate $O(1/n^{\beta})$ has previously been proved for diffeomorphisms, we establish the decay rate $O(1/t^\beta)$ for typical flows. Applications include certain classes of semidispersing billiards, as well as dispersing billiards with vanishing curvature. In addition, we obtain results for suspension flows with unbounded roof functions. This includes the planar periodic Lorentz flow with infinite horizon.
|
[
"Mathematics Archive->math.DS"
] | 2006-11-06T21:12:50Z |
1407.7870
|
Non-linear bond-operator theory and 1/d expansion for coupled-dimer magnets I: Paramagnetic phase
|
For coupled-dimer Heisenberg magnets, a paradigm of magnetic quantum phase transitions, we develop a systematic expansion in 1/d, the inverse number of space dimensions. The expansion employs a formulation of the bond-operator technique and is based on the observation that a suitably chosen product-state wavefunction yields exact zero-temperature expectation values of local observables in the d->infty limit, with corrections vanishing as 1/d. We demonstrate the approach for a model of dimers on a hypercubic lattice, which generalizes the square-lattice bilayer Heisenberg model to arbitrary d. In this paper, we use the 1/d expansion to calculate static and dynamic observables at zero temperature in the paramagnetic singlet phase, up to the quantum phase transition, and compare the results with numerical data available for d=2. Contact is also made with previously proposed refinements of bond-operator theory as well as with a perturbative expansion in the inter-dimer coupling. In a companion paper, the present 1/d expansion will be extended to the ordered phase, where it is shown to consistently describe the entire phase diagram including the quantum critical point.
|
[
"Physics Archive->cond-mat->cond-mat.str-el"
] | 2014-07-29T20:02:15Z |
2204.09668
|
A double-peaked Lyman-$\alpha$ emitter with a strong blue peak multiply imaged by the galaxy cluster RXC J0018.5+1626
|
We report the discovery of a double-peaked Lyman-$\alpha$ (Ly$\alpha$) emitter (LAE) at $z=3.2177\pm0.0001$ in VLT/MUSE data. The galaxy is strongly lensed by the galaxy cluster RXC~J0018.5+1626 recently observed in the RELICS survey, and the double-peaked Ly$\alpha$ emission is clearly detected in the two counter images in the MUSE field-of-view. We measure a relatively high Ly$\alpha$ rest-frame equivalent width (EW) of $\mathrm{EW}_{\mathrm{Ly}\alpha,0}=(63\pm2)\,\mathring{\mathrm{A}}$. Additional near-infrared (NIR) spectroscopy allows us to measure the H$\beta$, [OIII]$\lambda4959\,\mathring{\mathrm{A}}$ and [OIII]$\lambda5007\,\mathring{\mathrm{A}}$ emission lines, which show moderate rest-frame EWs of the order of a few $\sim10-100\,\mathring{\mathrm{A}}$, an [OIII]$\lambda5007\,\mathring{\mathrm{A}}$/H$\beta$ ratio of $4.8\pm0.7$, and a lower limit on the [OIII]/[OII] ratio of $>5.6$. The galaxy has very blue UV-continuum slopes of $\beta_{\mathrm{FUV}}=-2.23\pm0.06$ and $\beta_{\mathrm{NUV}}=-3.0\pm0.2$, and is magnified by factors $\mu\sim7-10$ in each of the two images, thus enabling a view into a low-mass ($M_{\star}\simeq10^{7.5}\,\mathrm{M}_{\odot}$) high-redshift galaxy analog. Notably, the blue peak of the Ly$\alpha$ profile is significantly stronger than the red peak, which suggests an inflow of matter and possibly very low HI column densities in its circumgalactic gas. Combined with the high lensing magnification and image multiplicity, these properties make this galaxy a prime candidate for follow-up observations to search for LyC emission and constrain the LyC photon escape fraction.
|
[
"Physics Archive->astro-ph->astro-ph.GA"
] | 2022-04-20T17:58:27Z |
1108.3048
|
Fast Approximation Algorithms for Near-optimal Large-scale Network Monitoring
|
We study the problem of optimal traffic prediction and monitoring in large-scale networks. Our goal is to determine which subset of K links to monitor in order to "best" predict the traffic on the remaining links in the network. We consider several optimality criteria. This can be formulated as a combinatorial optimization problem, belonging to the family of subset selection problems. Similar NP-hard problems arise in statistics, machine learning and signal processing. Some include subset selection for regression, variable selection, and sparse approximation. Exact solutions are computationally prohibitive. We present both new heuristics as well as new efficient algorithms implementing the classical greedy heuristic - commonly used to tackle such combinatorial problems. Our approach exploits connections to principal component analysis (PCA), and yields new types of performance lower bounds which do not require submodularity of the objective functions. We show that an ensemble method applied to our new randomized heuristic algorithm, often outperforms the classical greedy heuristic in practice. We evaluate our algorithms under several large-scale networks, including real life networks.
|
[
"Computer Science Archive->cs.DS"
] | 2011-08-15T18:27:11Z |
2110.07317
|
ReGVD: Revisiting Graph Neural Networks for Vulnerability Detection
|
Identifying vulnerabilities in the source code is essential to protect the software systems from cyber security attacks. It, however, is also a challenging step that requires specialized expertise in security and code representation. To this end, we aim to develop a general, practical, and programming language-independent model capable of running on various source codes and libraries without difficulty. Therefore, we consider vulnerability detection as an inductive text classification problem and propose ReGVD, a simple yet effective graph neural network-based model for the problem. In particular, ReGVD views each raw source code as a flat sequence of tokens to build a graph, wherein node features are initialized by only the token embedding layer of a pre-trained programming language (PL) model. ReGVD then leverages residual connection among GNN layers and examines a mixture of graph-level sum and max poolings to return a graph embedding for the source code. ReGVD outperforms the existing state-of-the-art models and obtains the highest accuracy on the real-world benchmark dataset from CodeXGLUE for vulnerability detection. Our code is available at: \url{https://github.com/daiquocnguyen/GNN-ReGVD}.
|
[
"Computer Science Archive->cs.CR",
"Computer Science Archive->cs.LG"
] | 2021-10-14T12:44:38Z |
1703.04850
|
Variational methods for steady-state Darcy/Fick flow in swollen and poroelastic solids
|
Existence of steady states in elastic media at small strains with diffusion of a solvent or fluid due to Fick's or Darcy's laws is proved by combining usage of variational methods inspired from static situations with Schauder's fixed-point arguments. In the plain variant, the problem consists in the force equilibrium coupled with the continuity equation, and the underlying operator is non-potential and non-pseudomonotone so that conventional methods are not applicable. In advanced variants, electrically-charged multi-component flows through an electrically charged elastic solid are treated, employing critical points of the saddle-point type. Eventually, anisothermal variants involving heat-transfer equation are treated, too.
|
[
"Mathematics Archive->math.AP",
"Mathematics Archive->math.MP",
"Physics Archive->math-ph"
] | 2017-03-15T00:21:59Z |
1910.03160
|
Extraction of the CKM phase $\gamma$ from charmless two-body B meson decays
|
Utilizing all the experimental measured charmless $B \to PP$, $PV$ decay modes, where $P(V)$ denotes a light pseudoscalar (vector) meson, we extract the CKM angle $\gamma$ by global fit. All the unknown hadronic parameters are fitted with $\gamma$ together from experimental data, so as to make the approach least model dependent. The different contributions for various decay modes are classified by topological weak Feynman diagram amplitudes, which are to be determined by the global fit. To improve the precision of this approach, we consider flavor SU(3) breaking effects of topological diagram amplitudes among different decay modes by including the form factors and decay constants. The fitted result for CKM angle $\gamma$ is $(69.8 \pm 2.1 \pm 0.9) ^{\degree}$. It is consistent with the current world average with a better precision.
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->hep->hep-ph"
] | 2019-10-08T01:35:50Z |
astro-ph/9704222
|
The Wardle Instability in Interstellar Shocks: I. Nonlinear Dynamical Evolution
|
The nonlinear evolution of unstable C-type shocks in weakly ionized plasmas is studied by means of time-dependent magnetohydrodynamical simulations. This study is limited to shocks in magnetically dominated plasmas (in which the Alfven speed in the neutrals greatly exceeds the sound speed), and microphysical processes such as ionization and recombination are not followed. Both two-dimensional simulations of planar perpendicular and oblique C-type shocks, and fully three-dimensional simulation of a perpendicular shock are presented.
|
[
"Physics Archive->astro-ph"
] | 1997-04-23T00:15:43Z |
1411.2071
|
Newman's conjecture, zeros of the L-functions, function fields
|
De Bruijn and Newman introduced a deformation of the completed Riemann zeta function $\zeta$, and proved there is a real constant $\Lambda$ which encodes the movement of the nontrivial zeros of $\zeta$ under the deformation. The Riemann hypothesis is equivalent to the assertion that $\Lambda\leq 0$. Newman, however, conjectured that $\Lambda\geq 0$, remarking, "the new conjecture is a quantitative version of the dictum that the Riemann hypothesis, if true, is only barely so." Andrade, Chang and Miller extended the machinery developed by Newman and Polya to $L$-functions for function fields. In this setting we must consider a modified Newman's conjecture: $\sup_{f\in\mathcal{F}} \Lambda_f \geq 0$, for $\mathcal{F}$ a family of $L$-functions. We extend their results by proving this modified Newman's conjecture for several families of $L$-functions. In contrast with previous work, we are able to exhibit specific $L$-functions for which $\Lambda_D = 0$, and thereby prove a stronger statement: $\max_{L\in\mathcal{F}} \Lambda_L = 0$. Using geometric techniques, we show a certain deformed $L$-function must have a double root, which implies $\Lambda = 0$. For a different family, we construct particular elliptic curves with $p + 1$ points over $\mathbb{F}_p$. By the Weil conjectures, this has either the maximum or minimum possible number of points over $\mathbb{F}_{p^{2n}}$. The fact that $#E(\mathbb{F}_{p^{2n}})$ attains the bound tells us that the associated $L$-function satisfies $\Lambda = 0$.
|
[
"Mathematics Archive->math.NT"
] | 2014-11-08T02:01:32Z |
2112.15165
|
Giant magnon spin conductivity approaching the two-dimensional transport regime in ultrathin yttrium iron garnet films
|
Conductivities are key material parameters that govern various types of transport (electronic charge, spin, heat etc.) driven by thermodynamic forces. Magnons, the elementary excitations of the magnetic order, flow under the gradient of a magnon chemical potential in proportion to a magnon (spin) conductivity $\sigma_{m}$. The magnetic insulator yttrium iron garnet (YIG) is the material of choice for efficient magnon spin transport. Here we report an unexpected giant $\sigma_{m}$ in record-thin YIG films with thicknesses down to 3.7 nm when the number of occupied two-dimensional (2D) subbands is reduced from a large number to a few, which corresponds to a transition from 3D to 2D magnon transport. We extract a 2D spin conductivity ($\approx1$ S) at room temperature, comparable to the (electronic) spin conductivity of the high-mobility two-dimensional electron gas in GaAs quantum wells at millikelvin temperatures. Such high conductivities offer unique opportunities to develop low-dissipation magnon-based spintronic devices.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall"
] | 2021-12-30T18:46:31Z |
2005.06092
|
Adaptive Double-Exploration Tradeoff for Outlier Detection
|
We study a variant of the thresholding bandit problem (TBP) in the context of outlier detection, where the objective is to identify the outliers whose rewards are above a threshold. Distinct from the traditional TBP, the threshold is defined as a function of the rewards of all the arms, which is motivated by the criterion for identifying outliers. The learner needs to explore the rewards of the arms as well as the threshold. We refer to this problem as "double exploration for outlier detection". We construct an adaptively updated confidence interval for the threshold, based on the estimated value of the threshold in the previous rounds. Furthermore, by automatically trading off exploring the individual arms and exploring the outlier threshold, we provide an efficient algorithm in terms of the sample complexity. Experimental results on both synthetic datasets and real-world datasets demonstrate the efficiency of our algorithm.
|
[
"Computer Science Archive->cs.LG",
"Statistics Archive->stat.ML"
] | 2020-05-13T00:12:31Z |
2101.11625
|
Extended X-ray Emission in Compton Thick AGN with Deep Chandra Observations
|
We present the spatial analysis of five Compton thick (CT) active galactic nuclei (AGNs), including MKN 573, NGC 1386, NGC 3393, NGC 5643, and NGC 7212, for which high resolution Chandra observations are available. For each source, we find hard X-ray emission (>3 keV) extending to ~kpc scales along the ionization cone, and for some sources, in the cross-cone region. This collection represents the first, high-signal sample of CT AGN with extended hard X-ray emission for which we can begin to build a more complete picture of this new population of AGN. We investigate the energy dependence of the extended X-ray emission, including possible dependencies on host galaxy and AGN properties, and find a correlation between the excess emission and obscuration, suggesting a connection between the nuclear obscuring material and the galactic molecular clouds. Furthermore, we find that the soft X-ray emission extends farther than the hard X-rays along the ionization cone, which may be explained by a galactocentric radial dependence on the density of molecular clouds due to the orientation of the ionization cone with respect to the galactic disk. These results are consistent with other CT AGN with observed extended hard X-ray emission (e.g., ESO 428-G014 and the Ma et al. 2020 CT AGN sample), further demonstrating the ubiquity of extended hard X-ray emission in CT AGN.
|
[
"Physics Archive->astro-ph->astro-ph.GA",
"Physics Archive->astro-ph->astro-ph.HE"
] | 2021-01-27T19:00:02Z |
cond-mat/0305180
|
Characterization of elastic scattering near a Feshbach resonance in rubidium 87
|
The s-wave scattering length for elastic collisions between 87Rb atoms in the state |f,m_f>=|1,1> is measured in the vicinity of a Feshbach resonance near 1007 G. Experimentally, the scattering length is determined from the mean-field driven expansion of a Bose-Einstein condensate in a homogeneous magnetic field. The scattering length is measured as a function of the magnetic field and agrees with the theoretical expectation. The position and the width of the resonance are determined to be 1007.40 G and 0.20 G, respectively.
|
[
"Physics Archive->cond-mat"
] | 2003-05-08T15:32:30Z |
math/0507554
|
Manifolds with commuting Jacobi operators
|
We characterize Riemannian manifolds of constant sectional curvature in terms of commutation properties of their Jacobi operators.
|
[
"Mathematics Archive->math.DG"
] | 2005-07-27T09:46:29Z |
astro-ph/0404079
|
Cooling delay for protoquark stars due to neutrino trapping
|
The influence of neutrino trapping (NT) on the early cooling evolution of hot proto quark stars (PQS) with initial temperatures in the range T ~ 40 MeV is studied. Within a simplified model for the neutrino transport it is shown that the time for reaching neutrino opacity temperature of T_{opac} ~ 1 MeV is about 10 sec. This is an order of magnitude larger than without NT and of the same order as the duration long gamma ray bursts.
|
[
"Physics Archive->astro-ph"
] | 2004-04-05T01:46:44Z |
2101.06035
|
Hyper-order baryon number fluctuations at finite temperature and density
|
Fluctuations of conserved charges are sensitive to the QCD phase transition and a possible critical endpoint in the phase diagram at finite density. In this work, we compute the baryon number fluctuations up to tenth order at finite temperature and density. This is done in a QCD-assisted effective theory that accurately captures the quantum- and in-medium effects of QCD at low energies. A direct computation at finite density allows us to assess the applicability of expansions around vanishing density. By using different freeze-out scenarios in heavy-ion collisions, we translate these results into baryon number fluctuations as a function of collision energy. We show that a non-monotonic energy dependence of baryon number fluctuations can arise in the non-critical crossover region of the phase diagram. Our results compare well with recent experimental measurements of the kurtosis and the sixth-order cumulant of the net-proton distribution from the STAR collaboration. They indicate that the experimentally observed non-monotonic energy dependence of fourth-order net-proton fluctuations is highly non-trivial. It could be an experimental signature of an increasingly sharp chiral crossover and may indicate a QCD critical point. The physics implications and necessary upgrades of our analysis are discussed in detail.
|
[
"Physics Archive->hep->hep-ph",
"Physics Archive->nucl->nucl-ex",
"Physics Archive->nucl->nucl-th"
] | 2021-01-15T09:54:04Z |
cond-mat/0007176
|
ab initio modeling of open systems: charge transfer, electron conduction, and molecular switching of a C_{60} device
|
We present an {\it ab initio} analysis of electron conduction through a $C_{60}$ molecular device. Charge transfer from the device electrodes to the molecular region is found to play a crucial role in aligning the lowest unoccupied molecular orbital (LUMO) of the $C_{60}$ to the Fermi level of the electrodes. This alignment induces a substantial device conductance of $\sim 2.2 \times (2e^2/h)$. A gate potential can inhibit charge transfer and introduce a conductance gap near $E_F$, changing the current-voltage characteristics from metallic to semi-conducting, thereby producing a field effect molecular current switch.
|
[
"Physics Archive->cond-mat"
] | 2000-07-11T07:39:21Z |
1910.01383
|
Improving spatial resolution in X-ray microscopy by using tilted angle detector: A simulation study
|
Conventional x-ray imaging detectors suffer from parallax error when the radiation beam arrives at the detector surface at tilted angle. The image blurring occurs as the radiation penetrates detector material in lateral direction at tilted angle. However, at the photon energies used in x-ray microscopy the attenuation length of the x-rays in the detector material is shorter and consequently the parallax error due to the tilted angle irradiation can be smaller. In these cases, the tilted angle irradiation can be beneficial because it will expand the beam projection ("footprint") at the detector surface, improve spatial resolution and help to overcome inherent resolution limit of the detector. We have performed a simulation study to investigate the above trade-off between the parallax error and improved spatial resolution when tilted angle irradiation is used. Our simulation study showed that tilted angle irradiation at 2-5keV x-ray energies can provide substantial improvements of spatial resolution. We used in our studies the indirect-conversion x-ray microscopy detectors based on scintillators optically coupled to CCD and CMOS cameras, as well as direct-conversion detectors based on back illuminated (back thinned) CCD and CMOS cameras. We have demonstrated also that the tilted angle irradiation can prevent radiation damage of the direct conversion back illuminated CCD and CMOS cameras due to the shallow x-ray attenuation depths with tilted angle geometry.
|
[
"Physics Archive->physics->physics.ins-det"
] | 2019-10-03T10:19:35Z |
q-alg/9509005
|
Twisted representations of vertex operator algebras
|
Let $V$ be a vertex operator algebra and $g$ an automorphism of finite order. We construct an associative algebra $A_g(V)$ and a pair of functors between the category of $A_g(V)$-modules and a certain category of admissible $g$-twisted $V$-modules. In particular, these functors exhibit a bijection between the simple modules in each category. We give various applications, including the fact that the complete reducibility of admissible $g$-twisted modules implies both the finite-dimensionality of homogeneous spaces and the finiteness of the number of simple $g$-twisted modules.
|
[
"Mathematics Archive->math.QA"
] | 1995-09-06T19:48:15Z |
1503.08608
|
Freezing of energy of a soliton in an external potential
|
In this paper we study the dynamics of a soliton in the generalized NLS with a small external potential $\epsilon V$ of Schwartz class. We prove that there exists an effective mechanical system describing the dynamics of the soliton and that, for any positive integer $r$, the energy of such a mechanical system is almost conserved up to times of order $\epsilon^{-r}$. In the rotational invariant case we deduce that the true orbit of the soliton remains close to the mechanical one up to times of order $\epsilon^{-r}$.
|
[
"Mathematics Archive->math.MP",
"Physics Archive->math-ph"
] | 2015-03-30T09:23:06Z |
2208.11319
|
Solving the Kidney Exchange Problem Using Privacy-Preserving Integer Programming (Updated and Extended Version)
|
The kidney exchange problem (KEP) is to find a constellation of exchanges that maximizes the number of transplants that can be carried out for a set of pairs of patients with kidney disease and their incompatible donors. Recently, this problem has been tackled from a privacy perspective in order to protect the sensitive medical data of patients and donors and to decrease the potential for manipulation of the computing of the exchanges. However, the proposed approaches to date either only compute an approximative solution to the KEP or they suffer from a huge decrease in performance. In this paper, we suggest a novel privacy-preserving protocol that computes an exact solution to the KEP and significantly outperforms the other existing exact approaches. Our novel protocol is based on Integer Programming which is the most efficient method for solving the KEP in the non privacy-preserving case. We achieve an improved performance compared to the privacy-preserving approaches known to date by extending the output of the ideal functionality to include the termination decisions of the underlying algorithm. We implement our protocol in the SMPC benchmarking framework MP-SPDZ and compare its performance to the existing protocols for solving the KEP. In this extended version of our paper, we also evaluate whether and if so how much information can be inferred from the extended output of the ideal functionality.
|
[
"Computer Science Archive->cs.CR"
] | 2022-08-24T06:14:41Z |
hep-ph/9508290
|
Low-Energy Effective Lagrangian from Non-Minimal Supergravity with Unified Gauge Symmetry
|
From general supergravity theory with unified gauge symmetry, we obtain the low-energy effective Lagrangian by taking the flat limit and integrating out the superheavy fields in model-independent manner. The scalar potential possesses some excellent features. Some light fields classified by using supersymmetric fermion mass, in general, would get intermediate masses at the tree level after the supersymmetry is broken. We show that the stability of weak scale can be guaranteed under some conditions. There exist extra non-universal contributions to soft supersymmetry breaking terms which can give an impact on phenomenological study.
|
[
"Physics Archive->hep->hep-ph",
"Physics Archive->hep->hep-th"
] | 1995-08-14T08:50:04Z |
1806.02966
|
Effect of stochastic grain heating on cold dense clouds chemistry
|
The temperatures of dust grains play important roles in the chemical evolution of molecular clouds. Unlike large grains, the temperature fluctuations of small grains induced by photons may be significant. Therefore, if the grain size distribution is included in astrochemical models, the temperatures of small dust grains may not be assumed to be constant. We simulate a full gas-grain reaction network with a set of dust grain radii using the classical MRN grain size distribution and include the temperature fluctuations of small dust grains. Monte Carlo method is used to simulate the real-time dust grain's temperature fluctuations which is caused by the external low energy photons and the internal cosmic ray induced secondary photons. The increase of dust grains radii as ice mantles accumulate on grain surfaces is also included in our models. We found that surface CO$_2$ abundances in models with grain size distribution and temperature fluctuations are more than one order of magnitude larger than those with single grain size. Small amounts of terrestrial complex organic molecules (COMs) can also be formed on small grains due to the temperature spikes induced by external low energy photons. However, cosmic ray induced secondary photons overheat small grains so that surface CO sublime and less radicals are formed on grains surfaces, thus the production of surface CO$_2$ and COMs decreases by about one order of magnitude. The overheating of small grains can be offset by grain growth so that the formation of surface CO$_2$ and COMs becomes more efficient.
|
[
"Physics Archive->astro-ph->astro-ph.EP"
] | 2018-06-08T04:32:24Z |
1302.0976
|
Work distribution in time-dependent logarithmic-harmonic potential: exact results and asymptotic analysis
|
We investigate the distribution of work performed on a Brownian particle in a time-dependent asymmetric potential well. The potential has a harmonic component with time-dependent force constant and a time-independent logarithmic barrier at the origin. For arbitrary driving protocol, the problem of solving the Fokker-Planck equation for the joint probability density of work and particle position is reduced to the solution of the Riccati differential equation. For a particular choice of the driving protocol, an exact solution of the Riccati equation is presented. Asymptotic analysis of the resulting expression yields the tail behavior of the work distribution for small and large work values. In the limit of vanishing logarithmic barrier, the work distribution for the breathing parabola model is obtained.
|
[
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | 2013-02-05T09:54:14Z |
2303.06121
|
Ignorance is Bliss: Robust Control via Information Gating
|
Informational parsimony provides a useful inductive bias for learning representations that achieve better generalization by being robust to noise and spurious correlations. We propose \textit{information gating} as a way to learn parsimonious representations that identify the minimal information required for a task. When gating information, we can learn to reveal as little information as possible so that a task remains solvable, or hide as little information as possible so that a task becomes unsolvable. We gate information using a differentiable parameterization of the signal-to-noise ratio, which can be applied to arbitrary values in a network, e.g., erasing pixels at the input layer or activations in some intermediate layer. When gating at the input layer, our models learn which visual cues matter for a given task. When gating intermediate layers, our models learn which activations are needed for subsequent stages of computation. We call our approach \textit{InfoGating}. We apply InfoGating to various objectives such as multi-step forward and inverse dynamics models, Q-learning, and behavior cloning, highlighting how InfoGating can naturally help in discarding information not relevant for control. Results show that learning to identify and use minimal information can improve generalization in downstream tasks. Policies based on InfoGating are considerably more robust to irrelevant visual features, leading to improved pretraining and finetuning of RL models.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.LG"
] | 2023-03-10T18:31:50Z |
2205.04265
|
Zero-point Renormalization of the Band Gap of Semiconductors and Insulators Using the PAW Method
|
We evaluate the zero-point renormalization (ZPR) due to electron-phonon interactions of 28 solids using the projector-augmented-wave (PAW) method. The calculations cover diamond, many zincblende semiconductors, rock-salt and wurtzite oxides, as well as silicate and titania. Particular care is taken to include long-range electrostatic interactions via a generalized Fr\"ohlich model, as discussed in Phys. Rev. Lett. 115, 176401 (2015) and Phys. Rev. B 92, 054307 (2015). The data are compared to recent calculations, npj Computational Materials 6, 167 (2020), and generally very good agreement is found. We discuss in detail the evaluation of the electron-phonon matrix elements within the PAW method. We show that two distinct versions can be obtained depending on when the atomic derivatives are taken. If the PAW transformation is applied before taking derivatives with respect to the ionic positions, equations similar to the ones conventionally used in pseudopotential codes are obtained. If the PAW transformation is used after taking the derivatives, the full-potential spirit is largely maintained. We show that both variants yield very similar ZPRs for selected materials when the rigid-ion approximation is employed. In practice, we find however that the pseudo version converges more rapidly with respect to the number of included unoccupied states.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2022-05-09T13:35:24Z |
1508.07672
|
A possible framework of the Lipkin model obeying the su(n)-algebra in arbitrary fermion number. I --- The su(2)-algebras extended from the conventional fermion-pair and determination of the minimum weight states ---
|
The minimum weight states of the Lipkin model consisting of n single-particle levels and obeying the su(n)-algebra are investigated systematically. The basic idea is to use the su(2)-algebra which is independent of the su(n)-algebra. This idea has been already presented by the present authors in the case of the conventional Lipkin model consisting of two single-particle levels and obeying the su(2)-algebra. If following this idea, the minimum weight states are determined for any fermion number occupying appropriately n single-particle levels. Naturally, the conventional minimum weight state is included: all fermions occupy energetically the lowest single-particle level in the absence of interaction. The cases n=2, 3, 4 and 5 are discussed in rather detail.
|
[
"Physics Archive->nucl->nucl-th"
] | 2015-08-31T03:21:36Z |
2310.15813
|
Exploring the Risks and Challenges of National Electronic Identity (NeID) System
|
Many countries have embraced national electronic identification (NeID) systems, recognising their potential to foster a fair, transparent, and well-governed society by ensuring the secure verification of citizens' identities. The inclusive nature of NeID empowers people to exercise their rights while holding them accountable for fulfilling their obligations. Nevertheless, the development and implementation of these complex identity-verification systems have raised concerns regarding security, privacy, and exclusion. In this study, we discuss the different categories of NeID risk and explore the successful deployment of these systems, while examining how the specific risks and other challenges posed by this technology are addressed. Based on the review of the different NeID systems and the efforts made to mitigate the unique risks and challenges presented within each deployment, we highlighted the best practices for mitigating risk, including implementing strong security measures, conducting regular risk assessments, and involving stakeholders in the design and implementation of the system.
|
[
"Computer Science Archive->cs.CR"
] | 2023-10-24T13:09:50Z |
1010.2198
|
Nearness to Local Subspace Algorithm for Subspace and Motion Segmentation
|
There is a growing interest in computer science, engineering, and mathematics for modeling signals in terms of union of subspaces and manifolds. Subspace segmentation and clustering of high dimensional data drawn from a union of subspaces are especially important with many practical applications in computer vision, image and signal processing, communications, and information theory. This paper presents a clustering algorithm for high dimensional data that comes from a union of lower dimensional subspaces of equal and known dimensions. Such cases occur in many data clustering problems, such as motion segmentation and face recognition. The algorithm is reliable in the presence of noise, and applied to the Hopkins 155 Dataset, it generates the best results to date for motion segmentation. The two motion, three motion, and overall segmentation rates for the video sequences are 99.43%, 98.69%, and 99.24%, respectively.
|
[
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | 2010-10-11T19:47:41Z |
2103.11115
|
Directional shear-jamming
|
In this work we, study shear reversals of dense non-Brownian suspensions composed of cohesionless elliptical particles. By numerical simulations, we show that a new fragility appears for frictionless ellipses in the flowing states, where particles can flow indefinitely in one direction at applied shear stresses but shear-jams in the other direction upon shear stress reversal. This new fragility, absent in the isotropic particle case, is linked to the directional order of the elongated particles at steady shear and its reorientation at shear stress reversal, which forces the suspensions to pass through a more disordered state with an increased number of contacts in which it might get arrested.
|
[
"Physics Archive->cond-mat->cond-mat.soft"
] | 2021-03-20T06:50:08Z |
astro-ph/0502101
|
The 3-D shaping of NGC 6741: a massive, fast-evolving Planetary Nebula at the recombination--reionization edge
|
We infer the gas kinematics, diagnostics and ionic radial profiles, distance and central star parameters, nebular photo- ionization model, spatial structure and evolutionary phase of the PN NGC 6741 by means of long-slit high-resolution spectra at nine position angles. NGC 6741 (distance ~2.0 kpc, age ~1400 yr, ionized mass Mion ~0.06 Mo) is a dense (electron density up to 12,000 cm^(-3)), high-excitation, almost- prolate ellipsoid, surrounded by a sharp low-excitation skin (the ionization front), and embedded into a spherical (radius ~ 0.080 pc), almost-neutral, high-density (n(HI) ~7 x 10^3 atoms cm^(-3)) halo containing a large fraction of the nebular mass (Mhalo>0.20 Mo). The kinematics, physical conditions and ionic structure indicate that NGC 6741 is in a deep recombination phase, started about 200 years ago, and caused by the quick luminosity drop of the massive (M*=0.66-0.68 Mo), hot (logT* ~ 5.23) and faint (log L*/Lo ~ 2.75) post--AGB star, which has exhausted the hydrogen-shell nuclear burning and is moving along the white dwarf cooling sequence. The general expansion law of the ionized gas in NGC 6741, Vexp (km s^(-1)=13 x R", fails in the innermost, highest-excitation layers, which move slower than expected. The observed deceleration is ascribable to the luminosity drop of the central star, and appears in striking contrast to recent reports inferring that acceleration is a common property of the Planetary Nebulae innermost layers. Some general implications on the shaping mechanisms of Planetary Nebulae are discussed.
|
[
"Physics Archive->astro-ph"
] | 2005-02-04T15:01:44Z |
0708.2787
|
Complete interpolating sequences, the discrete Muckenhoupt condition, and conformal mapping
|
We extend the parameterization of sine-type functions in terms of conformal mappings onto slit domains given by Eremenko and Sodin to the more general case of generating functions of real complete interpolating sequences. It turns out that the cuts have to fulfill the discrete Muckenhoupt condition studied earlier by Lyubarskii and Seip.
|
[
"Mathematics Archive->math.CV"
] | 2007-08-21T09:31:07Z |
1210.0363
|
Status and results from the RAVE survey
|
RAVE, the RAdial Velocity Experiment, is a large spectroscopic survey which collects spectroscopic data for stars in the southern hemisphere. RAVE uses the AAO Schmidt telescope with a wavelength coverage similar to Gaia but a lower resolution of R=7,500. Since 2003, RAVE collected over 500,000 spectra providing an unprecedented dataset to study the structure and kinematics of the Milky Way and its stellar populations. In this review, we will summarize the main results obtained using the RAVE catalogues.
|
[
"Physics Archive->astro-ph->astro-ph.GA"
] | 2012-10-01T12:16:09Z |
1004.0254
|
The warping of extra spaces accelerates the expansion of the universe
|
Generic cosmological models derived from higher dimensional theories with warped extra dimensions have a nonzero cosmological constant-like term induced on the 3+1 space-time, or a physical 3-brane. In the scenario where this 3+1 space-time is an inflating de Sitter "brane" embedded in a higher-dimensional space-time, described by warped geometry, the 4D cosmological term is determined in terms of two length scales: one is a scale associated with the size of extra dimension(s) and the other is a scale associated with the warping of extra space(s). The existence of this term in four dimensions provides a tantalizing possibility of explaining the observed accelerating expansion of the universe from fundamental theories of gravity, e.g. string theory.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | 2010-04-01T23:36:48Z |
1312.1197
|
The return of the bow shock
|
Recently it has been discussed whether a bow shock ahead of the heliospheric stagnation region does exist or not. This discussion was triggered by measurements indicating that the Alfv\'en speed and that of fast magnetosonic waves are higher than the flow speed of the local interstellar medium (LISM) relative to the heliosphere and resulted in the conclusion that there might exist either a bow wave or a slow magnetosonic shock. We demonstrate here that including the He$^{+}$ component of the LISM yields both an Alfv\'en and fast magnetosonic wave speed lower than the LISM flow speed. Consequently, the scenario of a bow shock in front of the heliosphere as modelled in numerous simulations of the interaction of the solar wind with the LISM remains valid.
|
[
"Physics Archive->astro-ph->astro-ph.SR"
] | 2013-12-04T15:10:43Z |
2206.13940
|
Generalized uncertainty principle and burning stars
|
Gamow's theory of the implications of quantum tunneling on the star burning has two cornerstones including quantum mechanics and equipartition theorem. It has vastly been proposed that both of these foundations are affected by the existence of a non-zero minimum for length which usually appears in quantum gravity scenarios and leads to the Generalized Uncertainty principle (GUP). Mathematically, in the framework of quantum mechanics, the effects of GUP are considered as perturbation terms. Here, generalizing the de Broglie wavelength relation in the presence of minimal length, GUP correction to the Gamow's temperature is calculated and in parallel, an upper bound for the GUP parameter is estimated.
|
[
"Physics Archive->gr-qc"
] | 2022-06-25T07:00:17Z |
2106.14775
|
Low temperature thermodynamics of the antiferromagnetic $J_1-J_2$ model: Entropy, critical points and spin gap
|
The antiferromagnetic $J_1-J_2$ model is a spin-1/2 chain with isotropic exchange $J_1 > 0$ between first neighbors and $J_2 = \alpha J_1$ between second neighbors. The model supports both gapless quantum phases with nondegenerate ground states and gapped phases with $\Delta(\alpha) > 0$ and doubly degenerate ground states. Exact thermodynamics is limited to $\alpha = 0$, the linear Heisenberg antiferromagnet (HAF). Exact diagonalization of small systems at frustration $\alpha$ followed by density matrix renormalization group (DMRG) calculations returns the entropy density $S(T,\alpha,N)$ and magnetic susceptibility $\chi(T,\alpha,N)$ of progressively larger systems up to $N = 96$ or 152 spins. Convergence to the thermodynamics limit, $S(T,\alpha)$ or $\chi(T,\alpha)$, is demonstrated down to $T/J \sim 0.01$ in the sectors $\alpha < 1$ and $\alpha > 1$. $S(T,\alpha)$ yields the critical points between gapless phases with $S^\prime(0,\alpha) > 0$ and gapped phases with $S^\prime(0,\alpha) = 0$. The $S^\prime(T,\alpha)$ maximum at $T^*(\alpha)$ is obtained directly in chains with large $\Delta(\alpha)$ and by extrapolation for small gaps. A phenomenological approximation for $S(T,\alpha)$ down to $T = 0$ indicates power-law deviations $T^{-\gamma(\alpha)}$ from $\exp(-\Delta(\alpha)/T)$ with exponent $\gamma(\alpha)$ that increases with $\alpha$. The $\chi(T,\alpha)$ analysis also yields power-law deviations, but with exponent $\eta(\alpha)$ that decreases with $\alpha$. $S(T,\alpha)$ and the spin density $\rho(T,\alpha) = 4T\chi(T,\alpha)$ probe the thermal and magnetic fluctuations, respectively, of strongly correlated spin states. Gapless chains have constant $S(T,\alpha)/\rho(T,\alpha)$ for $T < 0.10$. Remarkably, the ratio decreases (increases) with $T$ in chains with large (small) $\Delta(\alpha)$.
|
[
"Physics Archive->cond-mat->cond-mat.str-el"
] | 2021-06-28T14:47:29Z |
math/0509123
|
Connectedness of Hilbert scheme strata defined by bounding cohomology
|
Let Hilb^p be the Hilbert scheme parametrizing the closed subschemes of P^n with Hilbert polynomial p \in Q[t] over a field K of characteristic zero. By bounding below the cohomological Hilbert functions of the points of Hilb^p we define locally closed subspaces of the Hilbert scheme. The aim of this thesis is to show that some of these subspaces are connected. For this we exploit the ideals constructed by D. Mall. It turns out that these ideals are sequentially Cohen-Macaulay and that their initial ideals and their generic initial ideals coincide for any admissible term order.
|
[
"Mathematics Archive->math.AC",
"Mathematics Archive->math.AG"
] | 2005-09-06T15:25:23Z |
1407.4377
|
Recovery-Based Error Estimators for Diffusion Problems: Explicit Formulas
|
We introduced and analyzed robust recovery-based a posteriori error estimators for various lower order finite element approximations to interface problems in [9, 10], where the recoveries of the flux and/or gradient are implicit (i.e., requiring solutions of global problems with mass matrices). In this paper, we develop fully explicit recovery-based error estimators for lower order conforming, mixed, and non- conforming finite element approximations to diffusion problems with full coefficient tensor. When the diffusion coefficient is piecewise constant scalar and its distribution is local quasi-monotone, it is shown theoretically that the estimators developed in this paper are robust with respect to the size of jumps. Numerical experiments are also performed to support the theoretical results.
|
[
"Mathematics Archive->math.NA"
] | 2014-07-16T16:30:19Z |
1903.12589
|
Coordinated Beam Selection in Millimeter Wave Multi-User MIMO Using Out-of-Band Information
|
Using out-of-band (OOB) side-information has recently been shown to accelerate beam selection in single-user millimeter wave (mmWave) massive MIMO communications. In this paper, we propose a novel OOB-aided beam selection framework for a mmWave uplink multi-user system. In particular, we exploit spatial information extracted from lower (sub-6 GHz) bands in order to assist with an inter-user coordination scheme at mmWave bands. To enforce coordination, we propose an exchange protocol exploiting device-to-device communications, where low-rate beam-related information is exchanged between the mobile terminals. The decentralized coordination mechanism allows the suppression of the so-called co-beam interference which would otherwise lead to irreducible interference at the base station side, thereby triggering substantial spectral efficiency gains.
|
[
"Computer Science Archive->cs.IT",
"Electrical Engineering and Systems Science Archive->eess.SP",
"Mathematics Archive->math.IT"
] | 2019-03-29T16:03:13Z |
1309.1013
|
Affine Maps Between CAT(0) Spaces
|
We study affine maps between CAT(0) spaces with geometric actions, and show that they essentially split as products of dilations and linear maps (on the Euclidean factor). This extends known results from the Riemannian case. Furthermore, we prove a splitting lemma for the Tits boundary of a CAT(0) space with geometric action, a variant of a splitting lemma for geodesically complete CAT(1) spaces by Lytchak.
|
[
"Mathematics Archive->math.GT"
] | 2013-09-04T12:53:58Z |
1909.08780
|
Direct CP violation in internal W-emission dominated baryonic B decays
|
The observation of CP violation has been experimentally verified in numerous $B$ decays but is yet to be confirmed in final states with half-spin particles. We focus our attention on baryonic $B$-meson decays mediated dominantly through internal $W$-emission processes and show that they are promising processes to observe for the first time the CP violating effects in $B$ decays to final states with half-spin particles. Specifically, we study the $\bar B^0\to p\bar p\pi^0(\rho^0)$ and $\bar B^0\to p\bar p\pi^+\pi^-$ decays. We obtain ${\cal B}(\bar B^0\to p\bar p\pi^0)=(5.0\pm 2.1)\times 10^{-7}$, in agreement with current data, and ${\cal B}(\bar B^0\to p\bar p\rho^0)\simeq {\cal B}(\bar B^0\to p\bar p\pi^0)/3$. Furthermore, we find ${\cal A}_{CP}(\bar B^0\to p\bar p\pi^0,p\bar p\rho^0,p\bar p\pi^+\pi^-) =(-16.8\pm 5.4,-12.6\pm 3.0,-11.4\pm 1.9)\%$. With measured branching fractions ${\cal B}(\bar B^0\to p\bar p\pi^0,p\bar p\pi^+\pi^-)\sim {\cal O}(10^{-6})$, we point out that ${\cal A}_{CP}\sim -(10-20)\%$ can be new observables for CP violation, accessible to the Belle~II and/or LHCb experiments.
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->hep->hep-ph"
] | 2019-09-19T02:35:20Z |
2103.00317
|
Ion-Beam Modification of Metastable Gallium Oxide Polymorphs
|
Gallium oxide with a corundum structure ({\alpha}-Ga2O3) has recently attracted great attention in view of electronic and photonic applications due to its unique properties including a wide band gap exceeding that of the most stable beta phase (\b{eta}-Ga2O3). However, the lower thermal stability of the {\alpha}-phase at ambient conditions in comparison with the \b{eta}-phase requires careful investigation of its resistance to other external influences such as ion irradiation, ion doping, etc. In this work, the structural changes under the action of Al+ ion irradiation have been investigated for a polymorphic gallium oxide layers grown by hydride vapor phase epitaxy on c-plane sapphire and consisting predominantly of {\alpha}-phase with inclusions of {\alpha}(\k{appa})-phase. It is established by the X-ray diffraction technique that inclusions of {\alpha}(\k{appa})-phase in the irradiated layer undergo the expansion along the normal to the substrate surface, while there is no a noticeable deformation for the {\alpha}-phase. This speaks in favor of the different radiation tolerance of various Ga2O3 polymorphs, especially the higher radiation tolerance of the {\alpha}-phase. This fact should be taken into account when utilizing ion implantation to modify gallium oxide properties in terms of development of efficient doping strategies.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci",
"Physics Archive->physics->physics.app-ph"
] | 2021-02-27T20:46:40Z |
1806.05804
|
Weakly Supervised Deep Image Hashing through Tag Embeddings
|
Many approaches to semantic image hashing have been formulated as supervised learning problems that utilize images and label information to learn the binary hash codes. However, large-scale labeled image data is expensive to obtain, thus imposing a restriction on the usage of such algorithms. On the other hand, unlabelled image data is abundant due to the existence of many Web image repositories. Such Web images may often come with images tags that contain useful information, although raw tags, in general, do not readily lead to semantic labels. Motivated by this scenario, we formulate the problem of semantic image hashing as a weakly-supervised learning problem. We utilize the information contained in the user-generated tags associated with the images to learn the hash codes. More specifically, we extract the word2vec semantic embeddings of the tags and use the information contained in them for constraining the learning. Accordingly, we name our model Weakly Supervised Deep Hashing using Tag Embeddings (WDHT). WDHT is tested for the task of semantic image retrieval and is compared against several state-of-art models. Results show that our approach sets a new state-of-art in the area of weekly supervised image hashing.
|
[
"Computer Science Archive->cs.CV"
] | 2018-06-15T05:24:30Z |
math/0602191
|
On the maximum number of cliques in a graph
|
A \emph{clique} is a set of pairwise adjacent vertices in a graph. We determine the maximum number of cliques in a graph for the following graph classes: (1) graphs with $n$ vertices and $m$ edges; (2) graphs with $n$ vertices, $m$ edges, and maximum degree $\Delta$; (3) $d$-degenerate graphs with $n$ vertices and $m$ edges; (4) planar graphs with $n$ vertices and $m$ edges; and (5) graphs with $n$ vertices and no $K_5$-minor or no $K_{3,3}$-minor. For example, the maximum number of cliques in a planar graph with $n$ vertices is $8(n-2)$.
|
[
"Mathematics Archive->math.CO"
] | 2006-02-09T19:59:00Z |
astro-ph/0409025
|
Distances of Quasars and Quasar-Like Galaxies: Further Evidence that QSOs may be Ejected from Active Galaxies
|
If high-redshift QSOs are ejected from the nuclei of low-redshift galaxies, as some have claimed, a large portion of their redshift must be intrinsic (non-Doppler). If these intrinsic components have preferred values, redshifts will tend to cluster around these preferred values and produce peaks in the redshift distribution. Doppler ejection and Hubble flow components will broaden each peak. Because ejection velocities are randomly directed and Hubble flow components are always positive, in this model all peaks are expected to show an asymmetry, extending further out in the red wing. If peaks are present showing this predicted asymmetry, it can lead directly to an estimate of quasar distances. Using two quasar samples, one with high redshifts and one with low, it is shown here that not only do all peaks in these two redshift distributions occur at previously predicted preferred values, they also all show the predicted extra extension in the red wing. For the low and high redshift samples the mean cosmological components are found to be z$_{c} \sim 0.024$ and $\sim 0.066$, respectively. The difference can be explained by the improved detection limit of the high redshift sample. These results offer further evidence in favor of the model proposing that QSOs are ejected from active galaxies.
|
[
"Physics Archive->astro-ph"
] | 2004-09-01T17:12:45Z |
1501.05573
|
Typical Event Horizons in AdS/CFT
|
We consider the construction of local bulk operators in a black hole background dual to a pure state in conformal field theory. The properties of these operators in a microcanonical ensemble are studied. It has been argued in the literature that typical states in such an ensemble contain firewalls, or otherwise singular horizons. We argue this conclusion can be avoided with a proper definition of the interior operators.
|
[
"Physics Archive->hep->hep-th"
] | 2015-01-22T16:53:36Z |
1502.04682
|
Accurate nuclear radii and binding energies from a chiral interaction
|
With the goal of developing predictive ab-initio capability for light and medium-mass nuclei, two-nucleon and three-nucleon forces from chiral effective field theory are optimized simultaneously to low-energy nucleon-nucleon scattering data, as well as binding energies and radii of few-nucleon systems and selected isotopes of carbon and oxygen. Coupled-cluster calculations based on this interaction, named NNLO$_{\rm sat}$, yield accurate binding energies and radii of nuclei up to $^{40}$Ca, and are consistent with the empirical saturation point of symmetric nuclear matter. In addition, the low-lying collective $J^\pi=3^-$ states in $^{16}$O and $^{40}$Ca are described accurately, while spectra for selected $p$- and $sd$-shell nuclei are in reasonable agreement with experiment.
|
[
"Physics Archive->nucl->nucl-ex",
"Physics Archive->nucl->nucl-th"
] | 2015-02-16T20:04:42Z |
hep-th/9211086
|
The Renormalization Group for Flag Manifolds
|
The renormalization group equations for a class of non--relativistic quantum $\sigma$--models targeted on flag manifolds are given. These models emerge in a continuum limit of generalized Heisenberg antiferromagnets. The case of the ${SU(3)\over U(1)\times U(1)}$ manifold is studied in greater detail. We show that at zero temperature there is a fixed point of the RG transformations in $(2+\varepsilon )$--dimensions where the theory becomes relativistic. We study the linearized RG transformations in the vicinity of this fixed point and show that half of the couplings are irrelevant. We also show that at this fixed point there is an enlargement of the global isometries of the target manifold. We construct a discrete non--abelian enlargement of this kind.
|
[
"Physics Archive->hep->hep-th"
] | 1992-11-19T11:27:00Z |
nlin/0006051
|
Effect of Mutation and Recombination on the Genotype-Phenotype Map
|
The effect of genetic operators other than selection, such as mutation and recombination, on the genotype-phenotype map is considered. In particular, when the genotypic fitness landscape exhibits a ``symmetry'', i.e. many genotypes corresponding to the same phenotype have equal fitness values, it is shown that such operators can break this symmetry. The consequences of this ``induced symmetry breaking'' are investigated. Specifically, it is shown that it generically leads to an increase in order or self-organization in the system and to the phenomenon of orthogenesis. Additionally, it is shown that it potentially leads to a more robust evolution circumventing some of the problems of brittleness. The above points are supported by explicit, analytic results associated with some simple one and two-locus models and also by some much more complicated numerical simulations.
|
[
"Physics Archive->nlin->nlin.AO"
] | 2000-06-30T21:32:16Z |
0907.4182
|
Ratio Estimators in Simple Random Sampling Using Information on Auxiliary Attribute
|
Some ratio estimators for estimating the population mean of the variable under study, which make use of information regarding the population proportion possessing certain attribute, are proposed. Under simple random sampling without replacement (SRSWOR) scheme, the expressions of bias and mean-squared error (MSE) up to the first order of approximation are derived. The results obtained have been illustrated numerically by taking some empirical population considered in the literature.
|
[
"Mathematics Archive->math.GM"
] | 2009-07-23T22:05:38Z |
0712.0903
|
Neutrino Sector with Majorana Mass Terms and Friedberg-Lee Symmetry
|
We examine a recently proposed symmetry/condition by Friedberg and Lee in the framework where three right-handed neutrinos are added to the spectrum of the three-family Minimal Standard Model. It is found that the right-handed neutrinos are very special, with respect to this symmetry. In the symmetry limit the neutrinos are massless and that may be a hint about why they are light. Imposed as a condition and not as a full symmetry, we find that one of the three right-handed neutrinos simply decouples (has only gravitational interactions) and that there is a massless interacting neutrino. The possible relation of the model to the see-saw mechanism is briefly discussed.
|
[
"Physics Archive->hep->hep-ph"
] | 2007-12-06T10:29:23Z |
1603.02911
|
Local Extrema of the $\Xi(t)$ Function and The Riemann Hypothesis
|
In the present paper we obtain a necessary and sufficient condition to prove the Riemann hypothesis in terms of certain properties of local extrema of the function $\Xi(t)=\xi(\tfrac{1}{2}+it)$. First, we prove that positivity of all local maxima and negativity of all local minima of $\Xi(t)$ form a necessary condition for the Riemann hypothesis to be true. After showing that any extremum point of $\Xi(t)$ is a saddle point of the function $\Re\{\xi(s)\}$, we prove that the above properties of local extrema of $\Xi(t)$ are also a sufficient condition for the Riemann hypothesis to hold at $t\gg 1$. We present a numerical example to illustrate our approach towards a possible proof of the Riemann hypothesis. Thus, the task of proving the Riemann hypothesis is reduced to the one of showing the above properties of local extrema of $\Xi(t)$.
|
[
"Mathematics Archive->math.NT"
] | 2016-03-05T01:38:42Z |
math/9706229
|
Characteristic p Galois representations that are produced by Drinfeld
|
We examine which representations of the absolute Galois group of a field of finite characteristic with image over a finite field of the same characteristic may be constructed by the Galois group's action on the division points of an appropriate Drinfeld module.
|
[
"Mathematics Archive->math.NT"
] | 1997-06-27T00:00:00Z |
0904.2160
|
Inferring Dynamic Bayesian Networks using Frequent Episode Mining
|
Motivation: Several different threads of research have been proposed for modeling and mining temporal data. On the one hand, approaches such as dynamic Bayesian networks (DBNs) provide a formal probabilistic basis to model relationships between time-indexed random variables but these models are intractable to learn in the general case. On the other, algorithms such as frequent episode mining are scalable to large datasets but do not exhibit the rigorous probabilistic interpretations that are the mainstay of the graphical models literature. Results: We present a unification of these two seemingly diverse threads of research, by demonstrating how dynamic (discrete) Bayesian networks can be inferred from the results of frequent episode mining. This helps bridge the modeling emphasis of the former with the counting emphasis of the latter. First, we show how, under reasonable assumptions on data characteristics and on influences of random variables, the optimal DBN structure can be computed using a greedy, local, algorithm. Next, we connect the optimality of the DBN structure with the notion of fixed-delay episodes and their counts of distinct occurrences. Finally, to demonstrate the practical feasibility of our approach, we focus on a specific (but broadly applicable) class of networks, called excitatory networks, and show how the search for the optimal DBN structure can be conducted using just information from frequent episodes. Application on datasets gathered from mathematical models of spiking neurons as well as real neuroscience datasets are presented. Availability: Algorithmic implementations, simulator codebases, and datasets are available from our website at http://neural-code.cs.vt.edu/dbn
|
[
"Computer Science Archive->cs.LG"
] | 2009-04-14T17:32:00Z |
2007.02732
|
Frobenius W-algebras and traces of Frobenius Heisenberg categories
|
To each symmetric graded Frobenius superalgebra we associate a W-algebra. We then define a linear isomorphism between the trace of the Frobenius Heisenberg category and a central reduction of this W-algebra. We conjecture that this is an isomorphism of graded superalgebras.
|
[
"Mathematics Archive->math.RT"
] | 2020-07-06T13:13:26Z |
1402.5403
|
Electroweak precision measurements in supersymmetric models with a U(1)R lepton number
|
As experimental constraints on the parameter space of the MSSM and close variations thereof become stronger, the motivation to explore supersymmetric models that challenge some of the standard assumptions of the MSSM also become stronger. For example, models where the gauginos are Dirac instead of Majorana have recently received more attention. Beside allowing for a supersoft SUSY breaking mechanism where the gauginos only provide finite threshold corrections to scalar masses, the cross section for the production of a squark pairs is reduced. In addition, Dirac gauginos can be used to build models that possess a U(1)R symmetry. This symmetry can then be identified with a lepton number, leading to models that are quite different from conventional scenarios. The sneutrinos in these models can acquire a vev and give mass to the leptons and the down-type squark. The phenomenology is novel, combining signatures that are typical of R-parity violating scenarios with signatures arising from leptoquarks. Correspondingly the constraints from electroweak precision data are also different. In these models, one of the leptons mixes with gauginos and superpotential Yukawa couplings can contribute to EWPM at tree level. In addition, lepton universality is broken. In this paper we adapt the operators analysis of Han and Skiba [1] to include the relevant violation of lepton universality, and do a global fit of the model to electroweak precision data, including all relevant tree-level and loop-level effects. We obtain bounds on the vev of the sneutrino and on the superpotential couplings of the model.
|
[
"Physics Archive->hep->hep-ph"
] | 2014-02-21T20:33:03Z |
1002.0051
|
Structural Investigations into Shwachman Bodian Diamond Syndrome SBDS using a Bioinformatics Approach
|
The functional correlation of missense mutations which cause disease remains a challenge to understanding the basis of genetic diseases. This is particularly true for proteins related to diseases for which there are no available three dimensional structures. One such disease is Shwachman Diamond syndrome SDS OMIM 260400, a multi system disease arising from loss of functional mutations. The Homo sapiens Shwachman Bodian Diamond Syndrome gene hSBDS is responsible for SDS. hSBDS is expressed in all tissues and encodes a protein of 250 amino acids SwissProt accession code Q9Y3A5. Sequence analysis of disease associated alleles has identified more than 20 different mutations in affected individuals. While a number of these mutations have been described as leading to the loss of protein function due to truncation, translation or surface epitope association, the structural basis for these mutations has yet to be determined due to the lack of a three-dimensional structure for SBDS.
|
[
"Quantitative Biology Archive->q-bio.BM"
] | 2010-01-30T07:53:46Z |
2203.01754
|
PINA: Learning a Personalized Implicit Neural Avatar from a Single RGB-D Video Sequence
|
We present a novel method to learn Personalized Implicit Neural Avatars (PINA) from a short RGB-D sequence. This allows non-expert users to create a detailed and personalized virtual copy of themselves, which can be animated with realistic clothing deformations. PINA does not require complete scans, nor does it require a prior learned from large datasets of clothed humans. Learning a complete avatar in this setting is challenging, since only few depth observations are available, which are noisy and incomplete (i.e. only partial visibility of the body per frame). We propose a method to learn the shape and non-rigid deformations via a pose-conditioned implicit surface and a deformation field, defined in canonical space. This allows us to fuse all partial observations into a single consistent canonical representation. Fusion is formulated as a global optimization problem over the pose, shape and skinning parameters. The method can learn neural avatars from real noisy RGB-D sequences for a diverse set of people and clothing styles and these avatars can be animated given unseen motion sequences.
|
[
"Computer Science Archive->cs.CV"
] | 2022-03-03T15:04:55Z |
hep-ph/9708432
|
Quenched and Partially Quenched Chiral Perturbation Theory for Vector and Tensor Mesons
|
Quenched and partially quenched chiral perturbation theory for vector mesons is developed and is used to extract chiral loop correction to the $\rho$ meson mass. Connections to fully quenched and totally unquenched chiral perturbation theory results are discussed. It is also shown that (partially) quenched perturbation theory for tensor mesons can be formulated analogously, and the chiral corrections for tensor meson masses are directly proportional to their counterparts in the vector meson sector. Utilizing this observation and non-relativistic quark model, we point out that mass difference $(m_{a_2} - {3 \over 2} m_\rho)$ is ``quenching-insensitive'' in large-$N_c$ limit. This quantity may be used for normalization of mass scale in lattice QCD calculations.
|
[
"Physics Archive->hep->hep-lat",
"Physics Archive->hep->hep-ph"
] | 1997-08-22T00:09:42Z |
2003.06342
|
Performance portability of lattice Boltzmann methods for two-phase flows with phase change
|
Numerical codes using the Lattice Boltzmann Methods (LBM) for simulating one- or two-phase flows are widely compiled and run on graphical process units. However, those computational units necessitate to re-write the program by using a low-level language which is suited to those architectures (e.g. CUDA for GPU NVIDIA or OpenCL). In this paper we focus our effort on the performance portability of LBM i.e. the possibility of writing LB algorithms with a high-level of abstraction while remaining efficient on a wide range of architectures such as multicores x86, GPU NVIDIA, ARM, and so on. For such a purpose, implementation of LBM is carried out by developing a unique code, LBM_saclay written in the C++ language, coupled with the Kokkos library for performance portability in the context of High Performance Computing. In this paper, the LBM is used to simulate a phase-field model for two-phase flow problems with phase change. The mathematical model is composed of the incompressible Navier-Stokes equations coupled with the conservative Allen-Cahn model. Initially developed in the literature for immiscible binary fluids, the model is extended here to simulate phase change occurring at the interface between liquid and gas. For that purpose, a heat equation is added with a source term involving the time derivative of the phase field. In the phase-field equation a source term is added to approximate the mass production rate at the interface. Several validations are carried out to check step-by-step the implementation of the full model. Finally, computational times are compared on CPU and GPU platforms for the physical problem of film boiling.
|
[
"Physics Archive->physics->physics.comp-ph",
"Physics Archive->physics->physics.flu-dyn"
] | 2020-03-13T15:15:55Z |
1606.03686
|
Does Having More Options Mean Harder to Reach Consensus?
|
We generalize a binary majority-vote model on adaptive networks to a plurality-vote counterpart. When opinions are uniformly distributed in the population of voters in the initial state, it is found that having more available opinions in the initial state actually accelerate the time to consensus. In particular, we investigate the three-state plurality-vote model. While time to consensus in two state model scales exponentially with population size $N$, for finite-size system, there is a non-zero probability that either the population reaches the consensus state in a time that is very short and independent of $N$ (in the heterophily regime), or in a time that scales exponentially with $N$ but is still much faster than two-state model.
|
[
"Physics Archive->physics->physics.soc-ph"
] | 2016-06-12T09:13:04Z |
2202.13847
|
TEScalib: Targetless Extrinsic Self-Calibration of LiDAR and Stereo Camera for Automated Driving Vehicles with Uncertainty Analysis
|
In this paper, we present TEScalib, a novel extrinsic self-calibration approach of LiDAR and stereo camera using the geometric and photometric information of surrounding environments without any calibration targets for automated driving vehicles. Since LiDAR and stereo camera are widely used for sensor data fusion on automated driving vehicles, their extrinsic calibration is highly important. However, most of the LiDAR and stereo camera calibration approaches are mainly target-based and therefore time consuming. Even the newly developed targetless approaches in last years are either inaccurate or unsuitable for driving platforms. To address those problems, we introduce TEScalib. By applying a 3D mesh reconstruction-based point cloud registration, the geometric information is used to estimate the LiDAR to stereo camera extrinsic parameters accurately and robustly. To calibrate the stereo camera, a photometric error function is builded and the LiDAR depth is involved to transform key points from one camera to another. During driving, these two parts are processed iteratively. Besides that, we also propose an uncertainty analysis for reflecting the reliability of the estimated extrinsic parameters. Our TEScalib approach evaluated on the KITTI dataset achieves very promising results.
|
[
"Computer Science Archive->cs.CV"
] | 2022-02-28T15:04:00Z |
1501.03621
|
Classification of multipartite systems featuring only $|W\rangle$ and $|GHZ\rangle$ genuine entangled states
|
In this paper we present several multipartite quantum systems featuring the same type of genuine (tripartite) entanglement. Based on a geometric interpretation of the so-called $|W\rangle$ and $|GHZ\rangle$ states we show that the classification of all multipartite systems featuring those and only those two classes of genuine entanglement can be deduced from earlier work of algebraic geometers. This classification corresponds in fact to classification of fundamental subadjoint varieties and establish a connection between those systems, well known in Quantum Information Theory and fundamental simple Lie algebras.
|
[
"Mathematics Archive->math.MP",
"Physics Archive->math-ph",
"Physics Archive->quant-ph"
] | 2015-01-15T10:29:38Z |
2306.07893
|
Rethinking Incentives in Recommender Systems: Are Monotone Rewards Always Beneficial?
|
The past decade has witnessed the flourishing of a new profession as media content creators, who rely on revenue streams from online content recommendation platforms. The reward mechanism employed by these platforms creates a competitive environment among creators which affect their production choices and, consequently, content distribution and system welfare. It is thus crucial to design the platform's reward mechanism in order to steer the creators' competition towards a desirable welfare outcome in the long run. This work makes two major contributions in this regard: first, we uncover a fundamental limit about a class of widely adopted mechanisms, coined Merit-based Monotone Mechanisms, by showing that they inevitably lead to a constant fraction loss of the optimal welfare. To circumvent this limitation, we introduce Backward Rewarding Mechanisms (BRMs) and show that the competition game resultant from BRMs possesses a potential game structure. BRMs thus naturally induce strategic creators' collective behaviors towards optimizing the potential function, which can be designed to match any given welfare metric. In addition, the BRM class can be parameterized to allow the platform to directly optimize welfare within the feasible mechanism space even when the welfare metric is not explicitly defined.
|
[
"Computer Science Archive->cs.GT"
] | 2023-06-13T16:38:47Z |
nucl-th/0109002
|
A dynamical chiral bag model
|
We study a dynamical chiral bag model, in which massless fermions are confined within an impenetrable but movable bag coupled to meson fields. The self-consistent motion of the bag is obtained by solving the equations of motion exactly assuming spherical symmetry. When the bag interacts with an external meson wave we find three different kinds of resonances: {\it fermionic}, {\it geometric}, and $\sigma$-resonances. We discuss the phenomenological implications of our results.
|
[
"Physics Archive->nucl->nucl-th"
] | 2001-09-03T09:38:51Z |
2307.06541
|
On the Effective Horizon of Inverse Reinforcement Learning
|
Inverse reinforcement learning (IRL) algorithms often rely on (forward) reinforcement learning or planning over a given time horizon to compute an approximately optimal policy for a hypothesized reward function and then match this policy with expert demonstrations. The time horizon plays a critical role in determining both the accuracy of reward estimate and the computational efficiency of IRL algorithms. Interestingly, an effective time horizon shorter than the ground-truth value often produces better results faster. This work formally analyzes this phenomenon and provides an explanation: the time horizon controls the complexity of an induced policy class and mitigates overfitting with limited data. This analysis leads to a principled choice of the effective horizon for IRL. It also prompts us to reexamine the classic IRL formulation: it is more natural to learn jointly the reward and the effective horizon together rather than the reward alone with a given horizon. Our experimental results confirm the theoretical analysis.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.LG"
] | 2023-07-13T03:06:36Z |
2310.11896
|
A New Multimodal Medical Image Fusion based on Laplacian Autoencoder with Channel Attention
|
Medical image fusion combines the complementary information of multimodal medical images to assist medical professionals in the clinical diagnosis of patients' disorders and provide guidance during preoperative and intra-operative procedures. Deep learning (DL) models have achieved end-to-end image fusion with highly robust and accurate fusion performance. However, most DL-based fusion models perform down-sampling on the input images to minimize the number of learnable parameters and computations. During this process, salient features of the source images become irretrievable leading to the loss of crucial diagnostic edge details and contrast of various brain tissues. In this paper, we propose a new multimodal medical image fusion model is proposed that is based on integrated Laplacian-Gaussian concatenation with attention pooling (LGCA). We prove that our model preserves effectively complementary information and important tissue structures.
|
[
"Computer Science Archive->cs.CV",
"Computer Science Archive->cs.LG",
"Electrical Engineering and Systems Science Archive->eess.IV"
] | 2023-10-18T11:29:53Z |
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