Miracle-dz/UniFAR-FTUs huggingface dataset:
The one-dimensional Bose-Hubbard Model with nearest-neighbor interaction

We study the one-dimensional Bose-Hubbard model using the Density-Matrix Renormalization Group (DMRG). For the cases of on-site interactions and additional nearest-neighbor interactions the phase boundaries of the Mott-insulators and charge density wave phases are determined. We find a direct phase transition between the charge density wave phase and the superfluid phase, and no supersolid or normal phases. In the presence of nearest-neighbor interaction the charge density wave phase is completely surrounded by a region in which the effective interactions in the superfluid phase are repulsive. It is known from Luttinger liquid theory that a single impurity causes the system to be insulating if the effective interactions are repulsive, and that an even bigger region of the superfluid phase is driven into a Bose-glass phase by any finite quenched disorder. We determine the boundaries of both regions in the phase diagram. The ac-conductivity in the superfluid phase in the attractive and the repulsive region is calculated, and a big superfluid stiffness is found in the attractive as well as the repulsive region.
The progenitors of short gamma-ray bursts

Recent months have witnessed dramatic progress in our understanding of short γ-ray burst (SGRB) sources. There is now general agreement that SGRBs—or at least a substantial subset of them—are capable of producing directed outflows of relativistic matter with a kinetic luminosity exceeding by many millions that of active galactic nuclei. Given the twin requirements of energy and compactness, it is widely believed that SGRB activity is ultimately ascribable to a modest fraction of a solar mass of gas accreting on to a stellar mass black hole (BH) or to a precursor stage whose inevitable end point is a stellar mass BH. Astrophysical scenarios involving the violent birth of a rapidly rotating neutron star, or an accreting BH in a merging compact binary driven by gravitational wave emission are reviewed, along with other possible alternatives (collisions or collapse of compact objects). If a BH lies at the centre of this activity, then the fundamental pathways through which mass, angular momentum and energy can flow around and away from it play a key role in understanding how these prime movers can form collimated, relativistic outflows. Flow patterns near BHs accreting matter in the hypercritical regime, where photons are unable to provide cooling, but neutrinos do so efficiently, are discussed in detail, and we believe that they offer the best hope of understanding the central engine. On the other hand, statistical investigations of SGRB niches also furnish valuable information on their nature and evolutionary behaviour. The formation of particular kinds of progenitor sources appears to be correlated with environmental effects and cosmic epoch. In addition, there is now compelling evidence for the continuous fuelling of SGRB sources. We suggest here that the observed late flaring activity could be due to a secondary accretion episode induced by the delayed fall back of material dynamically stripped from a compact object during a merger or collision. Some important unresolved questions are identified, along with the types of observation that would discriminate among the various models. Many of the observed properties can be understood as resulting from outflows driven by hyperaccreting BHs and subsequently collimated into a pair of anti-parallel jets. It is likely that most of the radiation we receive is reprocessed by matter quite distant to the BH; SGRB jets, if powered by the hole itself, may therefore be one of the few observable consequences of how flows near nuclear density behave under the influence of strong gravitational fields.
Interaction in the dark sector: a Bayesian analysis with latest observations

By combining cosmological probes at low, intermediate and high redshifts, we investigate the observational viability of a class of models with interaction in the dark sector. We perform a Bayesian analysis using the latest data sets of type Ia supernovae, baryon acoustic oscillations, the angular acoustic scale of the cosmic microwave background, and measurements of the expansion rate. When combined with the current measurement of the local expansion rate obtained by the Hubble Space Telescope, we find that these observations provide evidence in favour of interacting models with respect to the standard cosmology.
A simple mechanism for unconventional superconductivity in a repulsive fermion model

Motivated by a scarcity of simple and analytically tractable models of superconductivity from strong repulsive interactions, we introduce a simple tight-binding lattice model of fermions with repulsive interactions that exhibits unconventional superconductivity (beyond BCS theory). The model resembles an idealized trilayer. The Cooper pair consists of electrons on opposite sides of the dielectric, which mediates the attraction. In the strong coupling limit, we use degenerate perturbation theory to show that the model reduces to a superconducting hard-core Bose-Hubbard model. Above the superconducting critical temperature, an analog of pseudo-gap physics results where the fermions remain Cooper paired with a large single-particle energy gap.
Dirac fermion confinement in graphene

We study the problem of Dirac fermion confinement in graphene in the presence of a perpendicular magnetic field $B$. We show, analytically and numerically, that confinement leads to anomalies in the electronic spectrum and to a magnetic-field-dependent crossover from $\sqrt{B}$, characteristic of Dirac-Landau-level behavior, to linear-in-$B$ behavior, characteristic of confinement. This crossover occurs when the radius of the Landau level becomes of the order of the width of the system. As a result, we show that the Shubnikov--de Haas oscillations also change as a function of field, and lead to a singular Landau plot.
A Non-Singular Boundary Integral Equation for Acoustic Problems

Abstract A weakly singular boundar integral equation and a non-singular one are derived for acoustic problems. By using the one-dimensional wave propagation mode, the degree of the singularities appearing in the conventional boundary integral equation can be reduced. Since the strong singularity is removed in the weakly singular equation, the jump term of the field pressure expression in the very vicinity of the boundary disappears. It is shown that the weak singularity can be also removed for a smooth boundary in the non-singular representation, and thus special treatments for singular integral are no longer needed. In order to test the proposed method, several simple problems have been solved by employing the triangular element with standard Gaussian quadrature integration points. The results obtained show the accuracy of the method in the near field as well as on the boundary.
Binomial Multiplicative Model of Critical Fragmentation

We report the binomial multiplicative model for low impact energy fragmentation. Impact fragmentation experiments were performed for low impact energy region, and it was found that the weighted mean mass is scaled by the pseudo control parameter multiplicity. We revealed that the power of this scaling is a non-integer (fractal) value and has a multi-scaling property. This multi-scaling can be interpreted by a binomial multiplicative (simple biased cascade) model. Although the model cannot explain the power-law of fragment-mass cumulative distribution in fully fragmented states, it can produce the multi-scaling exponents that agree with experimental results well.
Modifications of the Rayleigh and Bingham Tests for Uniformity of Directions

The general machinery of Cordeiro and Ferrari (1991, Biometrika78, 573? 582) and Chandra and Mukerjee (1991, J. Multivariate Anal.36, 103? 112) provides modifications of score test statistics which bring the null distributions close to their large-sample asymptotic distributions. These modifications are calculated here for the Rayleigh and Bingham tests of uniformity on spheres of arbitrary dimension, Stiefel manifolds, rotation groups, Grassmann manifolds and complex projective spaces.
Perception of temporally interrupted speech: Effects of two concurrent gating rates on intelligibility.

Perception of temporally interrupted speech was investigated with either one or two concurrent square‐wave gating functions. Sentences were interrupted at a single rate of 1, 2, 4, 8, 16, 24, or 32 Hz with a 50% duty cycle. For each rate between 1 to 8 Hz, stimuli were additionally gated at a secondary rate ranging from twice the primary rate up to 32 Hz. The secondary gating rate thus interrupted only the segments of speech which were left intact after application of the primary gating function to reduce by half the remaining speech content independent of secondary rate. With a single gating function, intelligibility scores increased with rate, reaching perfect accuracy at 8 Hz. Application of the second gating function led to a decrease in intelligibility which was greatest when the secondary rate was twice the primary rate, a condition equivalent to a 25% duty cycle of the primary rate. Further increase in the secondary rate generally led to an improvement in intelligibility, although never to the leve.
The electron-cyclotron maser instability as the source of solar type V continuum

In this paper, it is proposed that the electron-cyclotron (EC) maser instability can be the source of solar type V bursts. The propagation of electrons up an open field line is examined, and it is shown that the resultant distribution can be subject to the bump-in-tail (BIT) or the EC maser instabilities, or both. The characteristics of the emission from the BIT and EC maser instabilities when they are driven by such distributions are compared. It is proposed that type V bursts are produced by the coalescence of the upper hybrid waves produced by the maser instability, while type IIIs are produced by the BIT instability. 26 references.
The Job Performance of Fly-In-Fly-Out Workers in Industrial Enterprises (on the Example of Oil and Gas Production, Diamond Mining Production, and Construction)

With high health requirements for FIFO work at industry, workers may experience adverse changes in psychological well-being and health status. This makes it relevant when developing the job performance model to rely on considering not only the effectiveness by employees but also their psychophysiological “cost of activity”, which is not reflected in modern scientific research. This article theoretically substantiates and empirically develops a job performance typology of fly-in-fly-out workers at industrial enterprises by correlating three components: effectiveness, psychophysiological resources, and the way of accomplishing tasks. The study involved 359 fly-in-fly-out workers in oil and gas, diamond mining and construction industries with different duration of the fly-in period, operating in the South and the North of the Russian Federation. The research methods included questioning, psychophysiological instrumental testing, and psychological testing. Statistical processing was carried out using the methods of descriptive statistics, two-stage cluster analysis, and multivariate analysis of variance. As a result of the study, six types of job performance of fly-in-fly-out personnel of industrial enterprises were identified. The employees at industrial enterprises of all six types of job performance correspond to their position and perform the assigned tasks, the difference in them lies in the desire to show an average or the highest possible result, as well as how much internal resources the employee spends to achieve this result and how quickly he restores them, which is expressed in terms of his state and well-being. Based on the results of these connections, measures for personnel management for industrial enterprises were proposed.
A guided map to the spiral arms in the galactic disk of the Milky Way

Abstract An up-to-date overview of the recent history is given, aiming is to present a helpful working guide to the literature and at the same time introduce key systems and observational results, starting from the Sun and going toward the Galactic Center and parts of the Zona Galactica Incognita, and beyond. We start by presenting an observational view of the Milky Way’s disk plane (cartographic, dynamical, chemical cross-cut, magnetic). This included the four long spiral arms in the disk of the Milky Way galaxy, their geometry, components, velocity, their widths and internal layers as well as onion-like ordered offsets, the central galactic bars, arm tangents, arm pitch and arm shape, arm origins near the Galactic Center, and other possible players in the spiral arm, such as the magnetic field and the dark matter content. After, we present a basic analysis of some theoretical predictions from galactic arm formation: numerical simulations or analytical theories, and observations are checked against predictions from various numerical simulations and analytical (theoretical) models.
Bootstrapping Chiral CFTs at Genus Two

Genus two partition functions of 2d chiral conformal field theories are given by Siegel modular forms. We compute their conformal blocks and use them to perform the conformal bootstrap. The advantage of this approach is that it imposes crossing symmetry of an infinite family of four point functions and also modular invariance at the same time. Since for a fixed central charge the ring of Siegel modular forms is finite dimensional, we can perform this analytically. In this way we derive bounds on three point functions and on the spectrum of such theories.
Subduction disruption, slab tears: ca. 1 Ma true collision of an ~30‐km‐thick oceanic plateau segment recorded by Yakutat slab nascent tear magmatism

Distinguishing the initiation of actual collision from flat‐slab subduction of oceanic buoyant highs along convergent margins is elusive because both can lead to inboard deformation and disrupt magmatic arcs. Volcanoes with nascent tear magmatic signatures provide a means to document both the occurrence and timing of actual oceanic buoyant high collision. There is a ~40‐year debate on when the true collision of the Yakutat plateau began in Alaska. Three newly identified ca. 1 Ma volcanoes with a north‐to‐south trench perpendicular orientation, nascent tear geochemical signatures, overlaying an imaged Yakutat slab tear, provide constraints on the timing of Yakutat collision and slab tearing. The ca. 1 Ma slab tear is coincident with Yakutat slab segmentation, northern continental Aleutian Arc rejuvenation, cessation of Wrangell Arc magmatism, increased collisional zone exhumation and eastern Yakutat trench abandonment. The documentation of nascent slab tear volcanoes may help resolve similar debates in other convergent margin settings.
H alpha as a Tracer of Mass Loss from OB Stars

This paper investigates the use of the H-alpha emission from stellar winds of OB stars to determine the stellar mass-loss rate. The power in H-alpha emitted by the wind can be parameterized in terms of the temperature and the density field of the wind. A simple expression is derived which relates the observed H-alpha luminosity to the stellar mass-loss rate, the stellar radius, the velocity law, and the stellar effective temperature. This expression is calibrated for the influence of the velocity law using a sample of Galactic OB stars with UV mass-loss rates. Consequently, the results depend on the validity of the UV rates. The derived velocity law for O stars turns out to be in agreement with the radiation-pressure-driven wind theory. There is evidence for a dependence of the velocity-law gradient on spectral type. The results for B stars, however, are more uncertain due to the dependence on the adopted mass accretion rate/L relation. Application of the calibrated H-alpha luminosity/mass-loss rate relation to a sample of 149 galactic OB stars shows that mass accretion rate can be reliably determined from H-alpha. Due to the moderate amount of observing time required to derive mass accretion rate from H-alpha, this methodmore » may be applied successfully to investigate mass-loss effects in extra-Galactic stars. 39 references. « less
Magnetohydrodynamics of a Drop

The nature of deformation and drag on a spherical drop of viscous, conducting and incompressible fluid under axisymmetric current distribution in a conducting, viscous, incompressible fluid of infinite extent is considered. The drop fluid and the ambient fluid phases are non‐reacting and non‐diffusive in nature. In low magnetic Reynolds' number approximation, the effects of space charge, either on the total force density or on the distribution of conduction currents are neglected. In the absence of any free induced currents, the drop deformation to oblate or prolate spheroidal shape in Stokes' approximation is primarily determined by the difference in conductivities and permeabilities of two fluid phases. The drag remains the same as that on a spherical drop in a noncurrent carrying fluid because of axisymmetric current distribution. In Oseen's approximation, the drop deformation to oblate spheroidal shape is aided by inertia of flow for large values of drop to ambient fluid density ratio, whereas inertia.
Association of Vitamin D deficiency with dyslipidemia, glycemic control and microalbuminuria in patients with type 2 Diabetes mellitus in Qatar

Background: Type 2 diabetes mellitus has been found to be associated with 25(OH)D (vitamin D) deficiency. The aim of this study was to the prevalence of vitamin D deficiency in T2DM patients in Qatar and the correlation between vitamin D deficiency and other variables such as dyslipidemia and glycemic control and microalbuminuria. Methods: This retrospective cross-sectional analytical study was carried out at the Hamad General Hospital medical outpatient clinic, in which adult patients (? 18 years) with type 2 DM were involved, between January 1, 2018, and July 31, 2018. Ethical approval was obtained from medical research committee. Results: We recruited 400 subjects with type 2 diabetes mellitus. Their mean age was 58.97±10.32 years and the majority were women (52.0%) and Arabs (69.5%). The mean duration of type 2 diabetes diagnosis was 14.94±8.99 years and mean. The prevalence of vitamin D deficiency was 29.5%. A comparison between vitamin D deficiency and non-vitamin D deficiency groups, showed a statistically significant difference in terms of fasting blood sugar (P<0.001), random blood sugar (P<0.001), HBA1c (P<0.001), total cholesterol (P=0.001), LDL (C) (P=0.004), HDL (C) (P<0.001), triglyceride (P<0.001), and Urinary Albumin Excretion Rate (P=0.007). Data analysis showed that a significant negative correlation was found between vitamin D level and fasting blood sugar (r= -0.208, P<0.001), random blood sugar (r= -0.20, P<0.001), HBA1c (r= -0.260, P<0.001), total cholesterol (r= -0.218, P<0.001), LDL (C) (r= -0.176, P=0.004), triglyceride (r= -0.342, P<0.001), and Urinary Albumin Excretion Rate (r= -0.184, P=0.007). Conclusion: Our study showed a significant correlation between vitamin D deficiency and the poor control of T2DM, dyslipidemia, and microalbuminuria. The results emphasize the importance of monitoring vitamin D status in high-risk populations.
Neutrino breakup of A=3 nuclei in supernovae

We extend the virial equation of state to include {sup 3}H and {sup 3}He nuclei, and predict significant mass-three fractions near the neutrinosphere in supernovae. While alpha particles are often more abundant, we demonstrate that energy transfer cross sections for muon and tau neutrinos at low densities are dominated by breakup of the loosely-bound {sup 3}H and {sup 3}He nuclei. The virial coefficients involving A=3 nuclei are calculated directly from the corresponding nucleon-{sup 3}H and nucleon-{sup 3}He scattering phase shifts. For the neutral-current inelastic cross sections and the energy transfer cross sections, we perform ab initio calculations based on microscopic two- and three-nucleon interactions and meson-exchange currents.
A direct gravitational lensing test for 10 exp 6 solar masses black holes in halos of galaxies

We propose a method that will be able to detect or exclude the existence of 10 exp 6 solar masses black holes in the halos of galaxies. VLBA radio maps of two milliarcsecond jets of a gravitationally lensed quasar will show the signature of these black holes - if they exist. If there are no compact objects in this mass range along the line of sight, the two jets should be linear mappings of each other. If they are not, there must be compact objects of about 10 exp 6 solar masses in the halo of the galaxy that deform the images by gravitational deflection. We present numerical simulations for the two jets A and B of the double quasar 0957 + 561, but the method is valid for any gravitationally lensed quasar with structure on milliarcsecond scales. As a by-product from high-quality VLBA maps of jets A and B, one will be able to tell which features in the maps are intrinsic in the original jet and which are only an optical illusion, i.e., gravitational distortions by black holes along the line of sight.
Rapid suppression of the charge density wave in YBa 2 Cu 3 O 6.6 under hydrostatic pressure

We report on the effects of hydrostatic pressure (HP) on the charge density wave observed in underdoped cuprates. We studied YBa$_2$Cu$_3$O$_{6.6}$ ($T_c$=61 K) using high-resolution inelastic x-ray scattering (IXS), and reveal an extreme sensitivity of the phonon anomalies related to the charge density wave (CDW) order to HP. The amplitudes of the normal state broadening and superconductivity induced phonon softening at Q$_{CDW}$ rapidly decrease as HP is applied, resulting in the complete suppression of signatures of the CDW below $\sim$1 GPa. Additional IXS measurements on YBa$_2$Cu$_3$O$_{6.75}$ demonstrate that this very rapid effect cannot be explained by pressure-induced modification of the doping level and highlight the different role of external pressure and doping in tuning the phase diagram of the cuprates. Our results provide new insights into the mechanisms underlying the CDW formation and its interplay with superconductivity.
Localized plasmonic losses at metal back contacts of thin-film silicon solar cells

Investigations of optical losses induced by localized plasmons in protrusions on silver back contacts of thin-film silicon solar cells are presented. The interaction of electromagnetic waves with nanoprotrusions on flat silver layers is simulated with a three-dimensional numerical solver of Maxwell's equations. Spatial absorption profiles and spatial electric field profiles as well as the absorption inside the protrusions are calculated. The results presented here show that the absorption of irradiated light at nanorough silver layers can be strongly enhanced by localized plasmonic resonances in Ag nanoprotrusions. Especially, localized plasmons in protrusions with a radius below 60 nm induce strong absorption, which can be several times the energy irradiated on the protrusion's cross section. The localized plasmonic resonances in single protrusions on Ag layers are observed to shift to longer wavelengths with increasing refractive index of the surrounding material. At wavelengths above 500 nm localized plasmonic resonances will increase the absorption of nanorough μc-Si:H/Ag interfaces. The localized plasmon induced absorption at nanorough ZnO/Ag interfaces lies at shorter wavelengths due to the lower refractive index of ZnO. For wavelengths above 500 nm, a high reflectivity of the silver back contacts is essential for the light-trapping of thin-film silicon solar cells. Localized-plasmon induced losses at silver back contacts can explain the experimentally observed increase of the solar cell performance when applying a ZnO/Ag back contact in comparison to a μc-Si:H/Ag back contact.