ShantanuT01/DACTYL-Pretraining huggingface dataset:
We include a fully coupled treatment of metal and dust enrichment into the Delphi semi-analytic model of galaxy formation to explain the dust content of 13 Lyman Break Galaxies (LBGs) detected by the Atacama Large millimetre Array (ALMA) REBELS Large Program at $z\simeq 7$. We find that the galaxy dust mass, $M_d$, is regulated by the combination of SNII dust production, astration, shock destruction, and ejection in outflows; grain growth (with a standard timescale $\tau_0= 30$ Myr) plays a negligible role. The model predicts a dust-to-stellar mass ratio of $\sim 0.07-0.1\%$ and a UV-to-total star formation rate relation such that $log (\psi_{\rm UV}) = -0.05 ~[log (\psi)]^{2} + 0.86 ~log(\psi) -0.05$ (implying that 55-80\% of the star formation is obscured) for REBELS galaxies with stellar mass $M_* = 10^{9-10} M_\odot$. This relation reconciles the intrinsic UV luminosity of LBGs with their observed luminosity function at $z=7$. However, 2 out of the 13 systems show dust-to-stellar mass ratios ($\sim 0.94-1.1\%$) that are up to $18\times$ larger than expected from the fiducial relation. Due to the physical coupling between dust and metal enrichment, even decreasing $\tau_0$ to very low values (0.3 Myr) only increases the dust-to-stellar mass ratio by a factor $ \sim 2$. Given that grain growth is not a viable explanation for such high observed ratios of the dust-to-stellar mass, we propose alternative solutions.
The energy density of energetic protons, U_p, in several nearby starburst nuclei (SBNs) has been directly deduced from gamma-ray measurements of the radiative decay of neutral pions produced in interactions with ambient protons. Lack of sufficient sensitivity and spatial resolution makes this direct deduction unrealistic in the foreseeable future for even moderately distant SBNs. A more viable indirect method for determining U_p in star-forming galaxies is to use its theoretically based scaling to the energy density of energetic electrons, U_e, which can be directly deduced from radio synchrotron and possibly also nonthermal hard X-ray emission. In order to improve the quantitative basis and diagnostic power of this leptonic method we reformulate and clarify its main aspects. Doing so we obtain a basic expression for the ratio U_p/U_e in terms of the proton and electron masses and the power-law indices that characterize the particle spectral distributions in regions where the total particle energy density is at equipartition with that of the mean magnetic field. We also express the field strength and the particle energy density in the equipartition region in terms of the region's size, mean gas density, IR and radio fluxes, and distance from the observer, and determine values of U_p in a sample of nine nearby and local SBNs.
We report on optical high-dispersion spectroscopic monitoring observations of the Be/X-ray binary A0535+26/V725 Tau, carried out from November 2005 to March 2009. The main aim of these monitoring observations is to study spectral variabilities in the Be disc, on both the short (a week or so) and long (more than hundreds of days) timescales, by taking long-term frequent observations. Our four-year spectroscopic observations indicate that the V/R ratio, i.e., the relative intensity of the violet (V) peak to the red (R) one, of the double-peaked H-alpha line profile varies with a period of 500 days. The H-beta line profile also varies in phase with the H-alpha profile. With these observations covering two full cycles of the V/R variability, we reconstruct the 2-D structure of the Be disc by applying the Doppler tomography method to the H-alpha and H-beta emission line profiles, using a rigidly rotating frame with the V/R variability period. The resulting disc structure reveals non-axisymmetric features, which can be explained by a one-armed perturbation in the Be disc. It is the first time that an eccentric disc structure is directly detected by using a method other than the interferometric one.
We investigate the possibility to search for supersymmetry in the scattering of protons and Compton back-scattered laser light. We evaluate the cross sections for inelastic and elastic production of wino pairs for different electron-proton c.m.s. energies. For $\sqrt{s}=1\ TeV$ the cross section exceeds $1\ fb$ for $m_w<190\ GeV$.
Let k be a global field of characteristic not 2. We prove a local-global principle for the existence of self-dual normal bases, and more generally for the isomorphism of G-trace forms, of G-Galois algebras over k.
Structural, magnetic and magnetotransport properties of (Bi$_{1-x}$Eu$_x$)$_2$Se$_3$ thin films have been studied experimentally as a function of Eu content. The films were synthesized by MBE. It is demonstrated that Eu distribution is not uniform, it enter quint-layers forming inside them plain (pancake-like) areas containing Eu atoms, which sizes and concentration increase with the growth of Eu content. Positive magnetoresistance related to the weak antilocalization was observed up to 15K. The antilocalization was not followed by weak localization as theory predicts for nontrivial topological states. Surprisingly, the features of antilocalization were seen even at Eu content $x$ $=$ 0.21. With the increase of Eu content the transition to ferromagnetic state occurs at $x$ about 0.1 and with the Curie temperature $\approx$ 8K, that rises up to 64K for $x$ $=$ 0.21. At temperatures above 1-2 K, the dephasing length is proportional to $T^{-1/2}$ indicating the dominant contribution of inelastic $e-e$ scattering into electron phase breaking. However, at low temperatures the dephasing length saturates, that could be due to the scattering on magnetic ions.
A nested occupancy scheme in random environment is a generalization of the classical Karlin infinite balls-in-boxes occupancy scheme in random environment (with random probabilities). Unlike the Karlin scheme in which the collection of boxes is unique, there is a nested hierarchy of boxes, and the hitting probabilities of boxes are defined in terms of iterated fragmentation of a unit mass. In the present paper we assume that the random fragmentation law is given by stick-breaking in which case the infinite occupancy scheme defined by the first level boxes is known as the Bernoulli sieve. Assuming that $n$ balls have been thrown, denote by $K_n(j)$ the number of occupied boxes in the $j$th level and call the level $j$ intermediate if $j=j_n\to\infty$ and $j_n=o(\log n)$ as $n\to\infty$. We prove a multidimensional central limit theorem for the vector $(K_n(\lfloor j_n u_1\rfloor),\ldots, K_n(\lfloor j_n u_\ell\rfloor)$, properly normalized and centered, as $n\to\infty$, where $j_n\to\infty$ and $j_n=o((\log n)^{1/2})$. The present paper continues the line of investigation initiated in Buraczewski, Dovgay and Iksanov [Electron. J. Probab. 25: paper no. 123, 2020] in which the occupancy of intermediate levels $j_n\to\infty$, $j_n=o((\log n)^{1/3})$ was analyzed.
We present the science case for surveys with the Tianlai dish array interferometer tuned to the $\left[ 1300, 1400 \right] \mathrm{MHz}$ frequency range. Starting from a realistic generation of mock visibility data according to the survey strategy, we reconstruct a map of the sky and perform a foreground subtraction. We show that a survey of the North Celestial Polar cap during a year of observing time and covering an area of $150 \, \mathrm{deg^2}$ would reach a sensitivity of $ 1.5-2 \, \mathrm{mK} $ per $1 \, \mathrm{MHz} \times 0.25^2 \, \mathrm{deg^2 }$ voxel and be marginally impacted by mode-mixing. Tianlai would be able to detect a handful $(\sim 10)$ of nearby massive \HI clumps as well as a very strong cross-correlation signal of 21\,cm intensity maps with the North Celestial Cap Survey optical galaxies. We have also studied the performance of a mid-latitude survey, covering $\sim 1500 \, \mathrm{deg^2}$ centered on a declination of $\delta=55^\circ$, which overlaps the Sloan Digital Sky Survey footprint. Despite a higher noise level for the mid-latitude survey, as well as significant distortions due to mode mixing, Tianlai would be able to detect a highly significant cross-correlation between the 21\,cm signal and the Sloan spectroscopic galaxy sample. Using the extragalactic signals from either or both of these surveys, it will be possible to assess the impact of calibration uncertainties, antenna pattern uncertainties, sources of noise, and mode mixing for future surveys requiring higher sensitivity.
The understanding of very energy hadron cross sections in terms of a 'black disc' with an 'edge' is reviewed. The slow approach to 'Asymptopia' is explained by the 'Edge'. The disproportion of length or mass scales involved is probably due to the small pion massa.
Interface free energy is the contribution to the free energy of a system due to the presence of an interface separating two coexisting phases at equilibrium. It is also called surface tension. The content of the paper is 1) the definition of the interface free energy from first principles of statistical mechanics; 2) a detailed exposition of its basic properties. We consider lattice models with short range interactions, like the Ising model. A nice feature of lattice models is that the interface free energy is anisotropic so that some results are pertinent to the case of a crystal in equilibrium with its vapor. The results of section 2 hold in full generality.
The Boltzmann kinetic equation is obtained from an integro-differential master equation that describes a stochastic dynamics in phase space of an isolated thermodynamic system. The stochastic evolution yields a generation of entropy, leading to an increase of Gibbs entropy, in contrast to a Hamiltonian dynamics, described by the Liouville equation, for which the entropy is constant in time. By considering transition rates corresponding to collisions of two particles, the Boltzmann equation is attained. When the angle of the scattering produced by collisions is small, the master equation is shown to be reduced to a differential equation of the Fokker-Planck type. When the dynamics is of the Hamiltonian type, the master equation reduces to the Liouville equation. The present approach is understood as a stochastic interpretation of the reasonings employed by Maxwell and Boltzmann in the kinetic theory of gases regarding the microscopic time evolution.
One of the most fundamental tasks in quantum thermodynamics is extracting energy from one system and subsequently storing this energy in an appropriate battery. Both of these steps, work extraction and charging, can be viewed as cyclic Hamiltonian processes acting on individual quantum systems. Interestingly, so-called passive states exist, whose energy cannot be lowered by unitary operations, but it is safe to assume that the energy of any not fully charged battery may be increased unitarily. However, unitaries raising the average energy by the same amount may differ in qualities such as their precision, fluctuations, and charging power. Moreover, some unitaries may be extremely difficult to realize in practice. It is hence of crucial importance to understand the qualities that can be expected from practically implementable transformations. Here, we consider the limitations on charging batteries when restricting to the feasibly realizable family of Gaussian unitaries. We derive optimal protocols for general unitary operations as well as for the restriction to easier implementable Gaussian unitaries. We find that practical Gaussian battery charging, while performing significantly less well than is possible in principle, still offers asymptotically vanishing relative charge variances and fluctuations.
In this account, we describe the crazy-clock phenomenon involving the state I (low iodide and iodine concentration) to state II (high iodide and iodine concentration with new iodine phase) transition after a Briggs-Rauscher (BR) oscillatory process. While the BR crazy-clock phenomenon is known, it is the first time that crazy-clock behavior is linked and explained with the symmetry-breaking phenomenon, highlighting the entire process in a novel way. The presented phenomenon has been thoroughly investigated by running more than 60 experiments, and evaluated by using statistical cluster K-means analysis. The mixing rate, as well as the magnetic bar shape and dimensions, have a strong influence on the transition appearance. Although the transition for both mixing and no-mixing conditions are taking place completely randomly, by using statistical cluster analysis we obtain different numbers of clusters (showing the time-domains where the transition is more likely to occur). In the case of stirring, clusters are more compact and separated, revealed new hidden details regarding the chemical dynamics of nonlinear processes. The significance of the presented results is beyond oscillatory reaction kinetics since the described example belongs to the small class of chemical systems that shows intrinsic randomness in their response and it might be considered as a real example of a classical liquid random number generator.
We consider the germ of a reduced curve, possibly reducible. F.Delgado de la Mata proved that such a curve is Gorenstein if and only if its semigroup of values is symmetrical. We extend here this symmetry property to any fractional ideal of a Gorenstein curve. We then focus on the set of values of the module of logarithmic residues along plane curves or complete intersection curves, which determines and is determined by the values of the Jacobian ideal thanks to our symmetry theorem. Moreover, we give the relation with Kahler differentials, which are used in the analytic classification of plane branches. We also study the behaviour of logarithmic residues in an equisingular deformation of a plane curve.
The Davenport constant for a finite abelian group $G$ is the minimal length $\ell$ such that any sequence of $\ell$ terms from $G$ must contain a nontrivial zero-sum sequence. For the group $G=(\mathbb Z/n\mathbb Z)^2$, its value is $2n-1$, which is a classical result of Olson. The associated inverse question is to characterize those sequences of maximal length $2n-2$ that do not have a nontrivial zero-sum subsequence. A simple argument shows this to be equivalent to characterizing all minimal zero-sum sequences of maximal length $2n-1$, with a minimal zero-sum sequence being one that cannot have its terms partitioned into two proper, nontrivial zero-sum subsequences. This was done in a series of papers . However, there is a missing case in one of the required papers, leading to a missing case not treated in the portion of the proof. Both these deficiencies are corrected here. The correction contained in this manuscript will be incorporated into a larger, forthcoming work that encompasses the entirety of the characterization, and is posted in advance so that the corrected argument is made available to the research community before this larger project is completed.
Divergence exponents of the first-order quantum correction of a two-dimensional hard-sphere Bose atoms are obtained by an effective field theory method. The first-order correction to the ground-state energy density with respect to the zeroth-order is given by   $\cale_1/\cale_0 \sim |D-2|^{-\al}|\ln\gamma|^{-\al'}$, where $D$ is the spatial dimension, and $\gamma$ is the gas parameter ($\gamma=n a^D$). As $D \to 2$, $\al =\al'=1$. We show that the first-order quantum correction of the energy density is not perturbative in low dimensions of $D < 2.2$ regardless of any gas parameter which is much less that 1.
We investigate theoretically the effect of injection of plasmonic carriers from an optically-excited metal nanocrystal to a semiconductor contact or to attached molecules. The distributions of optically-excited hot carriers are dramatically different in metal nanocrystals with large and small sizes. In large nanocrystals, most carriers have very small energies and the hot carrier distribution resembles the case of a plasmon wave in bulk. In nanocrystals smaller than 20nm, the carrier distribution extends to larger energies and occupies the whole region E_{F}<E<omega. The physical reason for the above behaviors is non-conservation of momentum in a nanocrystal. Because of the above properties, nanocrystals of small sizes are most suitable for designing of opto-electronic and photosynthetic devices based on injection of plasmonic electrons and holes. The central parameter of the problem is DeltaN=omega/q_{L}*v_{F}, where q_{L} is the momentum transfer and v_{F} is the Fermi velocity. In gold nanocrystals, when DeltaN<7, the high-energy hot-electron generation is efficient. For larger parameters DeltaN, the number of high-energy electrons is greatly reduced. Another important factor is the polarization of the exciting light. For efficient excitation of carriers with high energies, the electric-field polarization vector should be perpendicular to a prism-like nanoantenna (slab or platelet) with a small width ~ 10-20 nm. We also show the relation between our theory for injection in plasmonic nanocrystals and the Fowler theory of injection from a bulk metal. Along with a prism geometry (or platelet geometry), we consider cubes. The results can be applied to design both purely solid-state opto-electronic devices and systems for photo-catalysis and solar conversion.
A new functional calculus, developed recently for a fully non-perturbative treatment of quantum gravity, is used to begin a systematic construction of a quantum theory of geometry. Regulated operators corresponding to areas of 2-surfaces are introduced and shown to be self-adjoint on the underlying (kinematical) Hilbert space of states. It is shown that their spectra are {\it purely} discrete indicating that the underlying quantum geometry is far from what the continuum picture might suggest. Indeed, the fundamental excitations of quantum geometry are 1-dimensional, rather like polymers, and the 3-dimensional continuum geometry emerges only on coarse graining. The full Hilbert space admits an orthonormal decomposition into finite dimensional sub-spaces which can be interpreted as the spaces of states of spin systems. Using this property, the complete spectrum of the area operators is evaluated. The general framework constructed here will be used in a subsequent paper to discuss 3-dimensional geometric operators, e.g., the ones corresponding to volumes of regions.
We describe the use of our chemical evolution model to reproduce the abundance patterns observed in a catalog of elliptical galaxies from the SDSS DR4. The model assumes ellipticals form by fast gas accretion, and suffer a strong burst of star formation followed by a galactic wind which quenches star formation. Models with fixed IMF failed in simultaneously reproducing the observed trends with the galactic mass. So, we tested a varying IMF; contrary to the diffused claim that the IMF should become bottom heavier in more massive galaxies, we find a better agreement with data by assuming an inverse trend, where the IMF goes from being bottom heavy in less massive galaxies to top heavy in more massive ones. This naturally produces a downsizing in star formation, favoring massive stars in largest galaxies. Finally, we tested the use of the Integrated Galactic IMF, obtained by averaging the canonical IMF over the mass distribution function of the clusters where star formation is assumed to take place. We combined two prescriptions, valid for different SFR regimes, to obtain the IGIMF values along the whole evolution of the galaxies in our models. Predicted abundance trends reproduce the observed slopes, but they have an offset relative to the data. We conclude that bottom-heavier IMFs do not reproduce the properties of the most massive ellipticals, at variance with previous suggestions. On the other hand, an IMF varying with galactic mass from bottom-heavier to top-heavier should be preferred
We propose a Ginzburg-Landau theory for a large and important part of the abelian quantum Hall hierarchy, including the prominently observed Jain sequences. By a generalized "flux attachment" construction we extend the Ginzburg-Landau-Chern-Simons composite boson theory to states obtained by both quasielectron and quasihole condensation, and express the corresponding wave functions as correlators in conformal field theories. This yields a precise identification of the relativistic scalar fields entering these correlators in terms of the original electron field.
The onset of plasticity in quenched martensitic microstructures is characterized by a low initial yield stress followed by an extremely strong initial hardening response, and then a sudden hardening saturation. Literature attributes this behavior to residual stresses and dislocations inherited from the martensitic transformation, or to microstructural heterogeneities causing strength differences among the grains. Here, we argue that orientation-dependent yielding of lath martensite due to inter-lath sliding, which induces a substructure boundary sliding mechanism, may also contribute significantly to the observed behavior. To demonstrate this, we systematically study its quantitative contribution to the elasto-plastic transition behavior in a numerical microstructural model. In the simulations, we employ an effective laminate model for the martensite packets which takes into account the yielding anisotropy due to sliding along the packet's habit plane orientation. To account for the effect of carbon content, martensitic microstructures with different levels of lath strength are considered. It is shown that the martensite packets with a favorable habit plane orientation start to yield earlier compared to those with an unfavorable orientation, which initially remain elastic. As a consequence, the macro-scale response of the microstructures exhibits a low yield stress, followed by a significant degree of initial hardening which continues until the saturation stress level is approached. The apparent work hardening rate depends on the contrast between the in-habit plane and out-of-habit plane yield strength used in the model.
A vicious walker system consists of N random walkers on a line with any two walkers annihilating each other upon meeting. We study a system of N vicious accelerating walkers with the velocity undergoing Gaussian fluctuations, as opposed to the position. We numerically compute the survival probability exponent, {\alpha}, for this system, which characterizes the probability for any two walkers not to meet. For example, for N = 3, {\alpha} = 0.71 \pm 0.01. Based on our numerical data, we conjecture that 1/8N(N - 1) is an upper bound on {\alpha}. We also numerically study N vicious Levy flights and find, for instance, for N = 3 and a Levy index {\mu} = 1 that {\alpha} = 1.31 \pm 0.03. Vicious accelerating walkers relate to no-crossing configurations of semiflexible polymer brushes and may prove relevant for a non-Markovian extension of Dyson's Brownian motion model.
We investigate non-vanishing properties of $L(f,s)$ on the real line, when $f$ is a Hecke eigenform of half-integral weight $k+{1\over 2}$ on $\Gamma_0(4).$
We prove that if two graphs of girth at least 6 have isomorphic squares, then the graphs themselves are isomorphic. This is the best possible extension of the results of Ross and Harary on trees and the results of Farzad et al. on graphs of girth at least 7. We also make a remark on reconstruction of graphs from their higher powers.
In this work, we show that very natural, apparently simple problems in quantum measurement theory can be undecidable even if their classical analogues are decidable. Undecidability hence appears as a genuine quantum property here. Formally, an undecidable problem is a decision problem for which one cannot construct a single algorithm that will always provide a correct answer in finite time. The problem we consider is to determine whether sequentially used identical Stern-Gerlach-type measurement devices, giving rise to a tree of possible outcomes, have outcomes that never occur. Finally, we point out implications for measurement-based quantum computing and studies of quantum many-body models and suggest that a plethora of problems may indeed be undecidable.