ShantanuT01/DACTYL-Pretraining huggingface dataset:
The acoustic wave-propagation without mean flow and heat flux can be described in terms of velocity and pressure by the compressible nonlinear Navier-Stokes equations, where boundary layers appear at walls due to the viscosity and a frequency interaction appears, $\textit{i.e.}$ sound at higher harmonics of the excited frequency $\omega$ is generated due to nonlinear advection. We use the multiharmonic analysis to derive asymptotic expansions for small sound amplitudes and small viscosities both of order $\varepsilon^2$ in which velocity and pressure fields are separated into far field and correcting near field close to walls and into contributions to the multiples of $\omega$. Based on the asymptotic expansion we present approximate models for either the pressure or the velocity for order $0$, $1$ and $2$, in which impedance boundary conditions include the effect of viscous boundary layers and contributions at frequencies $0$ and $2\cdot\omega$ depend nonlinearly on the approximation at frequency $\omega$. In difference to the Navier-Stokes equations in time domain, which has to be resolved numerically with meshes adaptively refined towards the wall boundaries and explicit schemes require the use of very small time steps, the approximative models can be solved in frequency domain on macroscopic meshes. We studied the accuracy of the approximated models of different orders in numerical experiments comparing with reference solutions in time-domain.
3D maps of the ISM can be used to locate not only IS clouds, but also IS bubbles between the clouds that are blown by stellar winds and supernovae. We compare our 3D maps of the IS dust to the ROSAT diffuse X-ray background maps. In the Plane, there is a good correspondence between the locations and extents of the mapped nearby cavities and the 0.25 keV background emission distribution, showing that most of these nearby cavities contribute to this soft X-ray emission. Assuming a constant dust to gas ratio and homogeneous 1MK hot gas filling the cavities, we modeled in a simple way the 0.25 keV surface brightness along the Galactic plane as seen from the Sun, taking into account the absorption by the mapped clouds. The data-model comparison favors the existence of hot gas in the Local Bubble (LB). The average mean pressure in the local cavities is found to be on the order of about 10,000 cm-3K, in agreement with previous studies. The model overestimates the emission from the huge cavities in the 3rd quadrant. Using CaII absorption data, we show that the dust to CaII ratio is very small in this region, implying the presence of a large quantity of lower temperature (non-X-ray emitting) ionized gas, explaining at least part of the discrepancy. In the meridian plane, the two main brightness enhancements coincide well with the chimneys connecting the LB to the halo. No nearby cavity is found towards the bright North Polar Spur (NPS) at high latitude. We searched in the maps for the source regions of the 0.75 keV enhancements in the 4th and 1st quadrants. Tunnels and cavities are found to coincide with the main bright areas, however no tunnel nor cavity is found to match the low-latitude, brightest part of the NPS. In addition, the comparison between the maps and published spectra do not favor the nearby cavities located within about 200pc as potential source regions for the NPS.
Data of Pierre Auger Observatory show a proton-dominated chemical composition of ultrahigh-energy cosmic rays spectrum at (1 - 3) EeV and a steadily heavier composition with energy increasing. In order to explain this feature we assume that (1 - 3) EeV protons are extragalactic and derive their maximum acceleration energy, E_p^{max} \simeq 4 EeV, compatible with both the spectrum and the composition. We also assume the rigidity-dependent acceleration mechanism of heavier nuclei, E_A^{max} = Z x E_p^{max}. The proposed model has rather disappointing consequences: i) no pion photo-production on CMB photons in extragalactic space and hence ii) no high-energy cosmogenic neutrino fluxes; iii) no GZK-cutoff in the spectrum; iv) no correlation with nearby sources due to nuclei deflection in the galactic magnetic fields up to highest energies.
The paper is concerned with the problem of explosive solutions for a class of semilinear stochastic wave equations. The challenging open problem(\cite{CMullR}) which is raised by C.Mueller and G.Richards is included in this problem.We develop an $\Omega_\delta$-comparative approach. With the aid of new approach, under appropriate conditions on the initial data and the nonlinear multiplicative noise term $(c_2u+f(u)) \dot{W}(t,x)$ with $|f(u)|\geq \kappa |u|^r,r>1,\kappa>0$, we prove in Theorem 3.1 that the solutions to the stochastic wave equation will blow up in finite time with positive probability.
Several results about positive solutions -in a Lipschitz domain- of a nonlinear elliptic equation in a general form $ \Delta u(x)-g(x,u(x))=0$ are proved, extending thus some known facts in the case of $ g(x,t)=t^q$, $q>1$, and a smooth domain. Our results include a characterization -in terms of a natural capacity- of a (conditional) removability property, a characterization of moderate solutions and of their boundary trace and a property relating arbitrary positive solutions to moderate solutions. The proofs combine techniques of non-linear p.d.e.\ with potential theoretic methods with respect to linear Schr\"odinger equations. A general result describing the measures that are diffuse with respect to certain capacities is also established and used. The appendix by the first author provides classes of functions $g$ such that the nonnegative solutions of $ \Delta u-g(.,u)=0$ has some "good" properties which appear in the paper.
By using a C3v symmetric (111) surface as a growth substrate, we are able to achieve high structural symmetry in self-assembled quantum dots, which are suitable for use as quantum-entangled photon emitters. Here we report on the wavelength controllability of InAs dots on InP(111)A, which we realized by tuning the ternary alloy composition of In(Al,Ga)As barriers that were lattice-matched to InP. We changed the peak emission wavelength systematically from 1.3 to 1.7 micrometer by barrier band gap tuning. The observed spectral shift agreed with the result of numerical simulations that assumed a measured shape distribution independent of barrier choice.
Most of the presently identified exoplanets have masses similar to that of Jupiter and therefore are assumed to be gaseous objects. With the ever-increasing interest in discovering lower-mass planets, several of the so-called super-Earths (1 M_earth<M<10 M_earth), which are predicted to be rocky, have already been found. Here we report the possible discovery of a planet around the M-type star GJ 436 with a minimum mass of 4.7+/-0.6 M_earth and a true mass of ~5 M_earth, which would make it the least massive planet around a main-sequence star found to date. The planet is identified from its perturbations on an inner Neptune-mass transiting planet (GJ 436b), by pumping eccentricity and producing variations in the orbital inclination. Analysis of published radial velocity measurements indeed reveals a significant signal corresponding to an orbital period that is very close to the 2:1 mean motion resonance with the inner planet. The near-grazing nature of the transit makes it extremely sensitive to small changes in the inclination.
We reinterpret the residue map for the Brauer group of a smooth variety using a root stack construction and Weil restriction for algebraic stacks, and apply the result to find a geometric representative of for the residue of a Brauer class associated to a conic bundle, or more generally a Brauer-Severi bundle.
The sensitivity afforded by quantum sensors is limited by decoherence. Quantum error correction (QEC) can enhance sensitivity by suppressing decoherence, but it has a side-effect: it biases a sensor's output in realistic settings. If unaccounted for, this bias can systematically reduce a sensor's performance in experiment, and also give misleading values for the minimum detectable signal in theory. We analyze this effect in the experimentally-motivated setting of continuous-time QEC, showing both how one can remedy it, and how incorrect results can arise when one does not.
Traffic accident anticipation aims to predict accidents from dashcam videos as early as possible, which is critical to safety-guaranteed self-driving systems. With cluttered traffic scenes and limited visual cues, it is of great challenge to predict how long there will be an accident from early observed frames. Most existing approaches are developed to learn features of accident-relevant agents for accident anticipation, while ignoring the features of their spatial and temporal relations. Besides, current deterministic deep neural networks could be overconfident in false predictions, leading to high risk of traffic accidents caused by self-driving systems. In this paper, we propose an uncertainty-based accident anticipation model with spatio-temporal relational learning. It sequentially predicts the probability of traffic accident occurrence with dashcam videos. Specifically, we propose to take advantage of graph convolution and recurrent networks for relational feature learning, and leverage Bayesian neural networks to address the intrinsic variability of latent relational representations. The derived uncertainty-based ranking loss is found to significantly boost model performance by improving the quality of relational features. In addition, we collect a new Car Crash Dataset (CCD) for traffic accident anticipation which contains environmental attributes and accident reasons annotations. Experimental results on both public and the newly-compiled datasets show state-of-the-art performance of our model. Our code and CCD dataset are available at https://github.com/Cogito2012/UString.
To date, density functional theory (DFT) is one of the most accurate and yet practical theory to gain insight about materials properties. Although successful, the computational cost is the main hurdle even today. A way out is combining DFT with machine learning (ML) to reduce the computational cost without compromising accuracy. However, the success of this approach hinges on the correctness of the descriptors. In the present work, we demonstrate that, based on {\it only} interatomic distances as descriptors, our ML model predicts interaction energy between an adsorbate and Al cluster with absolute mean error (AME) $\sim$ 0.05 eV (or less) and reproduces the PES experienced by an incoming atom. Our extensive DFT calculations reveal that atoms experiencing identical environment within a cluster have identical interaction energy patterns. Further, we demonstrate that our model is not specific to Al clusters, and could be applied to clusters of different elements as well. Its application to compute PES experienced by various test atoms and molecules in the vicinity of different clusters proves the transferability of the model not just to clusters of different elements but also to various molecules. The descriptors chosen are invariant to rotation, translation, and permutation yet very simple to compute is one of the most crucial points of the present work.
We introduce a novel interpretation of the sequence of commensurate lock-ins of the spiral wave vector, tau, observed in the helimagnetic phase of holmium in the presence of c-axis magnetic fields. This is the first successful model for the prediction of these lock-ins. We show that a model which combines a spin-slip model with an assumption concerning the spin structure along the c-axis in finite size ``domains'', yields excellent predictions when the energetics of this system with an applied c-axis magnetic field are considered.
Europium-doped lutetium-oxide (Eu:Lu2O3) nanoparticles were synthesized using a combustion technique and a co-precipitation technique, and their properties were compared. Surface-modification utilizing small silane molecules and long chain polymers were explored to de-agglomerate and disperse the particles. Structural, morphological and optical properties were characterized with x-ray diffraction, scanning and transmission electron microscopy, and laser spectroscopy respectively to evaluate these materials. The luminescent behaviors were compared between the pristine and modified Eu:Lu2O3 nanoparticles to study the influence of surface ligands on emission properties. Subsequently, the Eu:Lu2O3 nanoparticles were placed on top of a thin film consisting of silver nanoparticles and combined with silver nanoparticles and dispersed in a polymer matrix. The presence of the silver nanoparticles led to a reduction of the fluorescence lifetime of 12-14%.
Under the minimal SUSY standard model (MSSM), the discrepancy in the muon g-2 suggests the SUSY particles are of order 100 GeV, which is also supported by discussions on the little hierarchy problem. However, the LHC experiments have found no scalar-quarks or gluinos in such mass range, and moreover, the Higgs boson mass of 126 GeV requires, within the MSSM framework, the scalar-top mass of order 1-10 TeV. This current status forces us to abandon the simplest supersymmetry-breaking frameworks of the CMSSM and the GMSB scenarios.   The V-MSSM is investigated in this dissertation, which is proposed as an extension of the MSSM with a (10 + 10bar) pair of the SU(5) decuplets. In the framework the Higgs mass is increased by effect from the extra matters, and thus the 126 GeV is achieved with the scalar-top having a lighter mass. This fact resurrects the CMSSM and the GMSB scenarios. This dissertation examines the GMSB scenario under the V-MSSM; it is called V-GMSB scenario.   It is shown that the V-GMSB has a potential to realize the 126 GeV mass of the Higgs boson with holding the explanation of the muon magnetic moment discrepancy, if the masses of the extra quarks are approximately less than 1.2 TeV. Constraints on the V-GMSB from the LHC experiments are discussed then; it is concluded that the gluino mass must be approximately heavier than 1.1 TeV, and that the extra quarks be heavier than 300-650 GeV depending on the decay branches of them.   LHC prospects are briefly discussed. As the extra quarks are expected to be approximately less than 1.2 TeV, searches for the particles are of great interest at the 14 TeV LHC; constraints from the supersymmetry search, especially on the gluino mass, are expected to be much improved there. Therefore, it is expected that the fate of the V-GMSB is adjudicated at the court of the 14 TeV LHC.
The global attraction to stationary states is established for solutions to 3D wave equations with concentrated nonlinearities: each finite energy solution converges as $t\to\pm\infty$ to stationary states. The attraction is caused by nonlinear energy radiation.
There are 88 stars which lack colours, but have measured parallaxes in \textit{Gaia} EDR3 that place them within 20\,pc from the sun. Among them we found two new common parallax and proper motion (CPPM) companions separated from their primaries by about 3\,arcsec. The CPPM companion of a nearby ($d=14.98$\,pc) F1 star, \object{HD 105452 B}, was already imaged with the \textit{Hubble Space Telescope} and is now confirmed with \textit{Gaia} data and photometrically classified by us as M4 dwarf. The other CPPM companion, \object{SCR J1214-2345 B} orbiting an M4.5 dwarf at $d=10.77$\,pc, represents the faintest brown dwarf discovery made by \textit{Gaia} so far. It was also imaged by the VISTA Hemisphere Survey and partly detected in the near-infrared. Our photometric classification led to an uncertain spectal type of T1$\pm$3 and needs to be confirmed by spectroscopic follow-up.
An algebraic model based on Lie-algebraic techniques is applied to the analysis of thermodynamic vibrational properties of diatomic molecules. The local anharmonic effects are described by a Morse-like potential and corresponding anharmonic bosons associated with the U(2) algebra. A vibrational high temperature partition function and the related thermodynamic functions are derived in terms of the parameters of the model. The thermal expansion operator is defined and obtained using the renormalized frequency of the model.
We give the classification of the maximal infinite algebraic subgroups of the real Cremona group of the plane up to conjugacy and present a parametrisation space of each conjugacy class. Moreover, we show that the real plane Cremona group is not generated by a countable union of its infinite algebraic subgroups.
We report on the optical properties of the hole-doped manganites La_0.7Ca_0.3MnO_3 and La_0.7Ca_0.3MnO_3. Transmission and reflection of thin films are measured in the infrared at temperatures from 10 - 150 K using Fourier-transform spectroscopy. The scattering rate and optical mass are obtained by fitting the far-infrared transmission to a Drude model. The scattering rate shows a T^2 dependence with temperature. The optical mass enhancement differs only slightly from specific heat results. In addition, we compare the infrared spectral weight to band structure calculations [M. Quijada et al., Phys. Rev. B 58, 16093 (1998)].
The SpeX Prism Library (SPL) is a uniform compilation of low-resolution (R ~ 75-120), near-infrared (0.8-2.5 micron) spectra spanning a decade of observations with the IRTF SpeX spectrograph. Primarily containing ultracool M, L, T and Y dwarfs, this spectral library has been used in over 100 publications to date, facilitating a broad range of science on low mass stars, exoplanets, high redshift sources and instrument/survey design. I summarize the contents of the SPL and highlight a few of the key scientific results that have made use of this resource, as well as applications in education, outreach and art. I also outline the future plans of the SPL, which include a reanalysis of early data, better integration and dissemination of source and spectral metadata, conversion to Virtual Observatory formats, development of a Python software package for community analysis, and a design for a node-based visual programming platform that can facilitate citizen science and project-based learning in stellar spectroscopy.
Collaborative communication tasks such as random access codes (RACs) employing quantum resources have manifested great potential in enhancing information processing capabilities beyond the classical limitations. The two quantum variants of RACs, namely, quantum random access code (QRAC) and the entanglement-assisted random access code (EARAC), have demonstrated equal prowess for a number of tasks. However, there do exist specific cases where one outperforms the other. In this article, we study a family of $3 \rightarrow 1$ distributed RACs \cite{network} and present its general construction of both the QRAC and the EARAC. We demonstrate that, depending on the function of inputs that is sought, if QRAC achieves the maximal success probability then EARAC fails to do so and vice versa.Moreover, a tripartite Bell-type inequality associated with the EARAC variants reveals the genuine multipartite nonlocality exhibited by our protocol. We conclude with an experimental realization of the $3 \rightarrow 1$ distributed QRAC that achieves higher success probabilities than the maximum possible with EARACs for a number of tasks.
The work approaches the study of the fluctuations for the thermodynamic systems in the presence of the fields. The approach is of phenomenological nature and developed in a Gaussian approximation. The study is exemplified on the cases of a magnetizable continuum in a magnetoquasistatic field, as well as for the so called discrete systems. In the last case one finds that the fluctuations estimators depends both on the intrinsic properties of the system and on the characteristics of the environment. Following some earlier ideas of one of the authors we present a new class of thermodynamic inequalities for the systems investigated in this paper. In the case of two variables the mentioned inequalities are nothing but non-quantum analogues of the well known quantum Heisenberg (''uncertainty'') relations. Also the obtained fluctuations estimators support the idea that the Boltzmann's constant k has the signification of a generic indicator of stochasticity for thermodynamic systems.   Pacs number(s): 05.20.-y, 05.40.-a, 05.70.-a, 41.20.Gz
In this paper we compare the relaxation in several versions of the Sznajd model (SM) with random sequential updating on the chain and square lattice. We start by reviewing briefly all proposed one dimensional versions of SM. Next, we compare the results obtained from Monte Carlo simulations with the mean field results obtained by Slanina and Lavicka . Finally, we investigate the relaxation on the square lattice and compare two generalizations of SM, one suggested by Stauffer and another by Galam. We show that there are no qualitative differences between these two approaches, although the relaxation within the Galam rule is faster than within the well known Stauffer rule.
We present the analysis of the HI content of a sample of early-type galaxies (ETGs) in low-density environments (LDEs) using the data set provided by the Arecibo Legacy Fast ALFA (ALFALFA) survey. We compare their properties to the sample in the Virgo cluster that we studied in a previous paper (di Serego Alighieri et al. 2007, Paper I). We have selected a sample of 62 nearby ETGs (V< 3000 km/s) in an area of the sky where the ALFALFA data are already available (8h<RA<16h, 4 deg<DEC<16deg), avoiding the region of the Virgo cluster. Among these, 39 have absolute B magnitudes fainter than M_B = -17. Fifteen out of 62 galaxies have been firmly detected with ALFALFA (\sim 25%). Five additional galaxies show a weaker HI emission (S/N \sim 4) and they will need deeper observations to be confirmed. All together, our analysis doubles the number of known gas-rich ETGs in this area. The HI detection rate is 44% in luminous ETGs (M_B < -17) and 13% in dwarf ETGs (M_B > -17). In both cases it is 10 times higher than that of the Virgo cluster. The presence of gas can be related to a recent star formation activity: 60% of all ETGs with HI have optical emission line ratios typical of star-forming galaxies and blue colours suggesting the presence of young stellar populations, especially in the dwarf subsample. We show that the HI detection rate of ETGs depends both on the environment and mass. The fraction of early-type systems with neutral hydrogen is higher in more massive objects when compared to early-type dwarfs. The ETGs in LDEs seem to have more heterogeneous properties than their Virgo cluster counterparts, since they are able to retain a cold interstellar gas component and to support star formation activity even at recent epochs.
The growth and virialization of spherical top-hat fluctuations, in coupled Dark Energy models, causes segregation between Dark Matter (DM) and baryons, as the gravitational infall into the potential well proceeds more slowly for the baryons than for DM. As a consequence, after attaining their turn-around and before full virialization, halos have outer layers rich of baryons. Accordingly, a natural ambiguity exists on the definition of the virial density contrast. In fact, when the outer baryon layers infall onto the DM-richer core, they carry with them DM materials outside the original fluctuation; hence, no time exists when all materials originally belonging to the fluctuation -and only them- have virialized. Baryon-DM segregation can have various astrophysical consequences on different length-scales. The smallest halos may loose up to 50% of the original baryonic contents and become hardly visible. Subhalos in cluster-size halos may loose much baryonic materials, which could then be observed as intra-cluster light. Isolated halos, in general, can be expected to have a baryon component richer than the cosmological proportions, due to the cosmic enrichement of baryons lost in small halo encounters.