ShantanuT01/DACTYL-Pretraining huggingface dataset:
Tungsten carbide cobalt hardmetals are commonly used as cutting tools subject to high operation temperature and pressures, where the mechanical performance of the tungsten carbide phase affects the wear and lifetime of the material. In this study, the mechanical behaviour of the isolated tungsten carbide (WC) phase was investigated using single crystal micropillar compression. Micropillars in two crystal orientations, 1-5 ${\mu}$m in diameter, were fabricated using focused ion beam (FIB) machining and subsequently compressed between room temperature and 600 {\deg}C. The activated plastic deformation mechanisms were strongly anisotropic and weakly temperature dependent. The flow stresses of basal-oriented pillars were about three times higher than the prismatic pillars, and pillars of both orientations soften slightly with increasing temperature. The basal pillars tended to deform by either unstable cracking or unstable yield, whereas the prismatic pillars deformed by slip-mediated cracking. However, the active deformation mechanisms were also sensitive to pillar size and shape. Slip trace analysis of the deformed pillars showed that {10-10} prismatic planes were the dominant slip plane in WC. Basal slip was also activated as a secondary slip system at high temperatures.
A recently proposed device, dubbed half-Josephson laser, provides a phase-lock between the optical phase and the superconducting phase difference between the leads of the device. In this paper we propose to utilize this phase-lock for stabilization of voltage fluctuations, by two optical feedback schemes. The first scheme involves a single half-Josephson laser and allows to significantly decrease the diffusion coefficient of the superconducting phase difference. The second scheme involves a stable optical source and a fluctuating half-Josephson laser and permits quenching of the diffusion of the relative phase of the lasers. This opens up perspectives of the optical control of the superconducting phase and voltage fluctuations.
Let $G$ be a complex linear algebraic group which is simple of adjoint type. Let $\overline G$ be the wonderful compactification of $G$. We prove that the tangent bundle of $\overline G$ is stable with respect to every polarization on $\overline G$.
We study the cosmological build-up of pseudobulges using the LGalaxies semi-analytical model for galaxy formation with a new approach for following separately the assembly of classical bulges and pseudobulges. Classical bulges are assumed to be the result of violent processes (i.e., mergers and starbursts), while the formation of pseudobulges is connected to the secular growth of disks. We apply the model to both the Millennium and the Millennium II simulations, in order to study our results across a wide range of stellar masses ($10^{7} - 10^{11.5} M_{\odot}$). We find that $z=0$ pseudobulges mainly reside in galaxies of $ \rm M_{stellar} \sim 10^{10} - 10^{10.5} M_{\odot}$ ($\rm M_{halo} \sim 10^{11.5}-10^{12} M_{\odot}$) and we recover structural properties of these objects (e.g., sizes and bulge-to-total ratios) that are in good agreement with observational results. Tracing their formation history, we find that pseudobulges assembled in galaxies with a very quiet merger history, as opposed to the host galaxies of classical bulges. Regarding the bulge structure, we find that $\sim$ 30\% of the galaxies with a predominant pseudobulge feature a composite structure, hosting both a pseudo and a classical bulge component. The classical component typically constitutes $\sim$10\% of the total bulge galaxy mass. When looking at the properties of the host galaxies, we find that $z = 0$ pseudobulges are hosted by main sequence galaxies, characterized by a stellar population which is generally younger compared to the one of the hosts of classical bulges.
We introduce the notion of strong regular embeddings of Deligne-Mumford stacks. These morphisms naturally arise in the related contexts of generalized Euler sequences and hypertoric geometry.
Recent progress has been experienced in the field of hypernuclear weak decay, especially concerning the ratio of the neutron- to proton-induced Lambda non-mesonic decay rates, G_n/G_p. Theoretical analyses of nucleon coincidence data have been performed in a finite nucleus framework. They led to the extraction of G_n/G_p values in agreement with pure theoretical estimates, thus providing an evidence for the solution of a longstanding puzzle. Here we present an alternative approach to the problem, based on a nuclear matter formalism extended to finite nuclei via the local density approximation. The work is motivated by the exigence to make the determination of G_n/G_p from data less model dependent. One-meson-exchange potentials are used for describing both the one- and two-nucleon induced decays, Lambda N -> n N and Lambda N N -> n N N. For the latter, treated within a microscopic approach, the channels Lambda n n -> n n n and Lambda p p -> n p p are included in addition to the mode Lambda n p -> n n p already considered, in a phenomenological way, in previous studies. The propagation of the final nucleons in the residual nucleus is simulated by an intranuclear cascade code. We evaluate single and double coincidence nucleon spectra for the non-mesonic decay of C-12-Lambda. Through the comparison of our predictions with KEK coincidence data we determine G_n/G_p=0.43 \pm 0.10 for this hypernucleus, confirming previous finite nucleus analyses.
We discovered in simulations of sliding coaxial nanotubes an unanticipated example of dynamical symmetry breaking taking place at the nanoscale. While both nanotubes are perfectly left-right symmetric and nonchiral, a nonzero angular momentum of phonon origin appears spontaneously at a series of critical sliding velocities, in correspondence with large peaks of the sliding friction. The non-linear equations governing this phenomenon resemble the rotational instability of a forced string. However, several new elements, exquisitely "nano" appear here, with the crucial involvement of Umklapp and of sliding nanofriction.
We show that the BMN operators arise from the expansion of the Wilson loop in four-dimensional N=4 super Yang-Mills theory. The Wilson loop we consider is obtained from ``dimensional reduction'' of ten-dimensional N=1 super Yang-Mills theory, and it contains six scalar fields as well as the gauge field. We expand the Wilson loop twice. First we expand it in powers of the fluctuations around a BPS loop configuration. Then we further expand each term in the result of the first step in powers of the scalar field Z associated with the BPS configuration. We find that each operator in this expansion with large number of Z is the BMN operator. The number of fluctuations corresponds to the number of impurities, and the phase factor of each BMN operator is supplied correctly. We have to impose the BPS condition on the loop for obtaining the complete form of the BMN operators including the correction terms with \bar Z. Our observation suggests the correspondence between the Wilson loop and the string field.
In this paper we consider a class of stochastic differential equations driven by subordinate Brownian motion with Markovian switching. We use Malliavin calculus to study the smoothness of the density for the solution under uniform H\"ormander's type condition.
The grand-canonical version of the thermal model is used to analyze the ratios of particle abundances measured in ultra-relativistic heavy-ion collisions. Exactly the same model is applied to study the heavy-ion reactions at BNL AGS, CERN SPS, and BNL RHIC. A very good description is achieved for Pb+Pb collisions at SPS, and for Au+Au collisions at RHIC. In these two cases the value of the temperature characterizing the chemical freeze-out is practically same: T=168 MeV at SPS and T=165 MeV at RHIC. On the other hand, the particle ratios measured in the collisions of lighter nuclei are described only in the qualitative way. We discuss also the effect of the possible in-medium modifications of hadron masses and widths on the thermal fits. For Pb+Pb collisions at SPS and Au+Au collisions at RHIC we find that the chi^2 fits favor slightly a moderate (20%) decrease of the masses. In-medium modifications of the widths have little effect on the fits, unless they are increased by a factor larger than 2. We study in detail the thermodynamic conditions characterizing the chemical freeze-out. In particular, we find that the average baryon energy is 1.6 GeV and the average meson energy is 0.9 GeV. This difference reflects a different behavior of the mass spectra of mesons and baryons.
Hadron multiplicities in nucleus--nucleus interactions are calculated in the Dual Parton Model and its dependence on the number of collisions and the number of participants is analyzed. Shadowing corrections are calculated as a function of impact parameter and the multiplicity per participant as a funtion of centrality is found to be in agreement with experiment at SPS and RHIC energies. The obtained results are used to compute the $J/\psi$ suppression in a comover approach.
The star formation (SFH) and chemical enrichment (CEH) histories of Local Group galaxies are traditionally studied by analyzing their resolved stellar populations in a form of color-magnitude diagrams obtained with the Hubble Space Telescope. Star clusters can be studied in integrated light using ground-based telescopes to much larger distances. They represent snapshots of chemical evolution of their host galaxy at different ages. Here we present a simple theoretical framework for the chemical evolution based on the instantaneous recycling approximation (IRA) model. We infer a CEH from a SFH and vice versa using observational data. We also present a more advanced model for the evolution of individual chemical elements which takes into account the contribution of supernovae type Ia. We demonstrate that ages, iron and $\alpha$-element abundances of 15 star clusters derived from fitting of their integrated optical spectra reliably trace the CEH of the Large Magellanic Cloud obtained from resolved stellar populations in the age range 40Myr$<t<$3.5Gyr. The CEH predicted by our model from the global SFH of the LMC agrees remarkably well with the observed cluster age-metallicity relation. Moreover, the present day total gas mass of the LMC estimated by the IRA model ($6.2\cdot10^8 M_{\odot}$) matches within uncertainties the observed HI mass corrected for the presence of molecular gas ($5.8\pm0.5\cdot10^8 M_{\odot}$). We briefly discuss how our approach can be used to study SFHs of galaxies as distant as 10Mpc at the level of detail that is currently available only in a handful of nearby Milky Way satellites.
In this paper, we introduce a generalization of Balancing and Balancing-Lucas numbers. We describe some of their properties also we give the related matrix representation and divisibility properties.
We report a ground-based detection of the [OI] 63-um line in a z=6.027 gravitationally lensed dusty star-forming galaxy (DSFG) G09.83808 using the APEX SEPIA 660 receiver, the first unambiguous detection of the [OI]63 line beyond redshift 3, and the first obtained from the ground. The [OI]63 line is robustly detected at 22$\pm$5 Jy km s$^{-1}$, corresponding to an intrinsic (de-lensed) luminosity of $(5.4\pm1.3)\times10^{9}$ L$_\odot$. With the [OI]63/[CII] luminosity ratio of 4, the [OI]63 line is the main coolant of the neutral gas in this galaxy, in agreement with model predictions. The high [OI]63 luminosity compensates for the pronounced [CII] deficit ([CII]/FIR$\simeq4\times10^{-4}$). Using photon-dominated region models, we derive a source-averaged gas density $n=10^{4.0}$ cm$^{-3}$, and far-UV field strength $G=10^4 G_0$, comparable to the z=2-4 DSFG population. If G09.83808 represents a typical high-redshift DSFG, the [OI]63 line from z=6 non-lensed DSFGs should be routinely detectable in ALMA Band 9 observations with $\sim$15 min on-source, opening a new window to study the properties of the earliest DSFGs.
The presence of light thermally coupled dark matter affects early expansion history and production of light elements during the Big Bang Nucleosynthesis. Specifically, dark matter that annihilates into Standard Model particles can modify the effective number of light species in the universe $N_\mathrm{eff}$, as well as the abundance of light elements created buring BBN. These quantities in turn affect the cosmic microwave background (CMB) anisotropy. We present the first joint analysis of small-scale temperature and polarization CMB anisotropy from Atacama Cosmology Telescope (ACT) and South Pole Telescope (SPT), together with Planck data and the recent primordial abundance measurements of helium and deuterium to place comprehensive bounds on the mass of light thermal-relic dark matter. We consider a range of models, including dark matter that couples to photons and Standard-Model neutrinos. We find that the combination of ACT, SPT, and Planck generally leads to the most stringent mass constraint for dark matter that couples to neutrinos, improving the lower limit by 40%-80%, with respect to previous Planck analyses. On the other hand, the addition of ACT and SPT leads to a slightly weaker bound on electromagnetically coupled particles, due to a shift in the preferred values of $Y_\mathrm{p}$ and $N_\mathrm{eff}$ driven by the ground based experiments. Combining all CMB measurements with primordial abundance measurements, we rule out masses below $\sim$4 MeV at 95% confidence, for all models. We show that allowing for new relativistic species can weaken the mass bounds for dark matter that couples to photons by up to an order of magnitude or more. Finally, we discuss the reach of the next generation of the CMB experiments in terms of probing the mass of the thermal relic dark matter.
In this article, we prove (many parts of) the rank two case of the Kato's local epsilon-conjecture using the Colmez's p-adic local Langlands correspondence for GL_2(Q_p). We show that a Colmez's pairing defined in his study of locally algebraic vectors gives us the conjectural epsilon-isomorphisms for (almost) all the families of p-adic representations of Gal(overline{Q}_p/Q_p) of rank two, which satisfy the desired interpolation property for the de Rham and trianguline case. For the de Rham and non trianguline case, we also show this interpolation property for the "critical" range of Hodge-Tate weights using the Emerton's theorem on the compatibility of classical and p-adic local Langlands correspondence. As an application, we prove that the Kato's Euler system associated to any Hecke eigen new form satisfies a functional equation which has the same form as predicted by the Kato's global epsilon-conjecture.
We give a brief history of transcendental number theory, including Schanuel's conjecture (S). Assuming (S), we prove that if z and w are complex numbers, not 0 or 1, with z^w and w^z algebraic, then z and w are either both rational or both transcendental. A corollary is that if (S) is true, then we can find four distinct transcendental positive real numbers x, y, s, t such that the three numbers x^y=/=y^x and s^t=t^s are all integers. Another application (possibly known) is that (S) implies the transcendence of the numbers sqrt(2)^sqrt(2)^sqrt(2), i^i^i, and i^e^pi. We also prove that if (S) holds and a^a^z=z, where a=/=0 is algebraic and z is irrational, then z is transcendental.
We present new results from our ongoing multiplicity study of exoplanet host stars and present a list of 29 confirmed planet host multiple-star systems. Furthermore, we discuss the properties of these stellar systems and compare the properties of exoplanets detected in these systems with those of planets orbiting single stars.
We construct an analog of the intrinsic normal cone of Behrend-Fantechi in the equivariant motivic stable homotopy category over a base-scheme B and construct a fundament class in E-cohomology for any cohomology theory E in SH(B). For affine B, a perfect obstruction theory gives rise to a virtual fundamental class in a twisted Borel-Moore E-homology for arbitrary E. This includes motivic cohomology (homotopy invariant) K-theory algebraic cobordism and the oriented Chow groups of Barge-Morel and Fasel. In the case of motivic cohomology, we recover the constructions of Behrend-Fantechi, with values in the Chow group.
The purpose of this paper is to investigate a specific FRW model derived from the theory of N=1 supergravity with gauged supermatter. The supermatter content is restricted to a vector supermultiplet. This objective is particularly worthwhile. In fact, it was pointed in ref. ({\em Class. Quantum Grav. {\bf 12} {\rm (} {\rm 1995} {\rm )} {\rm 1343}}) that $\Psi = 0$ was the only allowed quantum state for N=1 supergravity with {\em generic} gauged supermatter subject to suitable FRW ans\"atze. The ans\"atze employed here for the physical variables was presented in the above reference. The corresponding Lorentz and supersymmetry quantum constraints are then derived. Non-trivial solutions are subsquently found. A no-boundary solution is identified while another state may be interpreted as a wormhole solution. In addition, the usefulness and limitations of the ans\"atze are addressed. The implications of the ans\"atze with respect to the allowed quantum states are also discussed.
We discuss the strong coupling of heavy mesons to a pion g, in the heavy quark limit. This quantity is quite remarkable since its values as estimated by different methods (various quark models and the QCD sum rules), are surprisingly different. The present quark models are mostly based on free spinors and their predictions depend crucially on the choice of the light quark mass. We propose a quark model based on the Dirac equation in a central potential, which gives a more refined description of Dirac spinors. We show that within such a Dirac model, the value of g is stable and large: g = 0.6(1), where we assume no quark current renormalization ((g_A)q = 1). Such a large result is strongly constrained by requiring that the model parameters fit the spectrum; we show that this implies a large ``effective'' light mass. It is also supported phenomenologically by a similar situation with heavy baryons, as well as by experience with nucleon (if one invokes additivity). We also calculate the couplings to heavy meson excitations, and show that the Adler-Weisberger sum rule is well saturated by a few levels (in contrast to the case of small g). We discuss uncertainties of our approach, and rise several questions which remain to be answered. The main mystery is the large, unusual discrepancy with QCD sum rules for g, whereas a good agreement is found for orbital excitations.
This paper considers recognizing products from daily photos, which is an important problem in real-world applications but also challenging due to background clutters, category diversities, noisy labels, etc. We address this problem by two contributions. First, we introduce a novel large-scale product image dataset, termed as Product-90. Instead of collecting product images by labor-and time-intensive image capturing, we take advantage of the web and download images from the reviews of several e-commerce websites where the images are casually captured by consumers. Labels are assigned automatically by the categories of e-commerce websites. Totally the Product-90 consists of more than 140K images with 90 categories. Due to the fact that consumers may upload unrelated images, it is inevitable that our Product-90 introduces noisy labels. As the second contribution, we develop a simple yet efficient \textit{guidance learning} (GL) method for training convolutional neural networks (CNNs) with noisy supervision. The GL method first trains an initial teacher network with the full noisy dataset, and then trains a target/student network with both large-scale noisy set and small manually-verified clean set in a multi-task manner. Specifically, in the stage of student network training, the large-scale noisy data is supervised by its guidance knowledge which is the combination of its given noisy label and the soften label from the teacher network. We conduct extensive experiments on our Products-90 and public datasets, namely Food101, Food-101N, and Clothing1M. Our guidance learning method achieves performance superior to state-of-the-art methods on these datasets.
The direct observation of gravitational waves will provide a unique tool for probing the dynamical properties of highly compact astrophysical objects, mapping ultra-relativistic regions of space-time, and testing Einstein's general theory of relativity. LISA (Laser Interferometer Space Antenna), a joint NASA-ESA mission to be launched in the next decade, will perform these scientific tasks by detecting and studying low-frequency cosmic gravitational waves through their influence on the phases of six modulated laser beams exchanged between three remote spacecraft. By directly measuring the polarization components of the waves LISA will detect, we will be able to test Einstein's theory of relativity with good sensitivity. Since a gravitational wave signal predicted by the most general relativistic metric theory of gravity accounts for {\it six} polarization modes (the usual two Einstein's tensor polarizations as well as two vector and two scalar wave components), we have derived the LISA Time-Delay Interferometric responses and estimated their sensitivities to vector- and scalar-type waves. We find that (i) at frequencies larger than roughly the inverse of the one-way light time ($\approx 6 \times 10^{-2} $ Hz.) LISA is more than ten times sensitive to scalar-longitudinal and vector signals than to tensor and scalar-transverse waves, and (ii) in the low part of its frequency band is equally sensitive to tensor and vector waves and somewhat less sensitive to scalar signals.
Several experiments (e.g., Milagro and IceCube) have reported the presence in the sky of regions with significant excess in the arrival direction distributions of Galactic cosmic rays in the TeV to PeV energy range. Here we study the possibility that these hotspots are a manifestation of the peculiar nature of these cosmic rays, and of the presence of molecular clouds near the sources. We propose that stable quark matter lumps or so-called "strangelets" can be emitted in the course of the transition of a neutron star to a more compact astrophysical object. A fraction of these massive particles would lose their charge by spallation or electron capture in molecular clouds located in the immediate neighborhood of their source, and propagate rectilinearly without decaying further, hence inducing anisotropies of the order of the cloud size. With reasonable astrophysical assumptions regarding the neutron star transition rate, strangelet injection and neutralization rates, we can reproduce successfully the observed hotspot characteristics and their distribution in the sky.
Atomic-scale calculations for the dynamics of the 90$^0$ partial glide dislocation in silicon are made using the effective-medium tight-binding theory. Kink formation and migration energies for the reconstructed partial dislocation are compared with experimental results for the mobility of this dislocation. The results confirm the theory that the partial moves in the dissociated state via the formation of stable kinks. The correlation between glide activation energy and band gap in semiconducting systems is discussed.