Miracle-dz/UniFAR-FTUs huggingface dataset:
Liouville equations for neutrino distribution matrices

The classical notion of a single-particle scalar distribution function or phase space density can be generalized to a matrix in order to accommodate superpositions of states of discrete quantum numbers, such as neutrino mass/flavor. Such a "neutrino distribution matrix" is thus an appropriate construct to describe a neutrino gas that may vary in space as well as time and in which flavor mixing competes with collisions. The Liouville equations obeyed by relativistic neutrino distribution matrices, including the spatial derivative and vacuum flavor mixing terms, can be explicitly but elegantly derived in two new ways: from a covariant version of the familiar simple model of flavor mixing, and from the Klein-Gordon equations satisfied by a quantum "density function" (mean value of paired quantum field operators). Associated with the latter derivation is a case study in how the joint position/momentum dependence of a classical gas (albeit with Fermi statistics) emerges from a formalism built on quantum fields.
Reduced thermal conductivity of TiNiSn/HfNiSn superlattices

Diminution of the thermal conductivity is a crucial aspect in thermoelectric research. We report a systematic and significant reduction of the cross-plane thermal conductivity in a model system consisting of dc sputtered TiNiSn and HfNiSn half-Heusler superlattices. The reduction of $\ensuremath{\kappa}$ is measured by the $3\ensuremath{\omega}$ method and originates from phonon scattering at the internal interfaces. Heat transport in the superlattices is calculated based on Boltzmann transport theory, including a diffusive mismatch model for the phonons at the internal interfaces. Down to a superlattice periodicity of 3 nm the phonon spectrum mismatch between the superlattice components quantitatively explains the reduction of $\ensuremath{\kappa}$. For very thin individual layers the interface model breaks down and the artificial crystal shows an enhanced $\ensuremath{\kappa}$.
The Analytical Solution to the Temporal Broadening of a Gaussian-Shaped Radio Pulse by Multipath Scattering from a Thin Screen in the Interstellar Medium

The radio pulse from a pulsar can be temporally broadened by multipath scattering in the interstellar medium and by instrumental effects within the radio telescope. The observed pulse shape is a convolution of the intrinsic one with the impulse responses of the scattering medium and instrumentation. Until recently, common methods used to model the observed shape made assumptions regarding the intrinsic pulse shape and impulse responses, computed the convolution numerically, and solved for the pulse width and scattering timescale iteratively. An analytical solution is shown to exist for the specific case of the temporal broadening of a Gaussian-shaped pulse by a thin scattering screen. The solution is applied to multi-frequency observations of PSR B1834–10 to characterize the frequency dependence of its intrinsic pulse width and scattering timescale.
The extent of gravitationally bound structure in a ΛCDM universe

A new analytical model for constraining the extent of gravitationally bound structure in the Universe is presented. This model is based on a simple modification of the spherical collapse model (SCM), and its performance in predicting the limits of bound structure in N-body simulations is compared to that of two previous models with the aid of new software named COLDGaS-- compute unified device architecture (CUDA) object location determination in GADGET2 snapshots -- which was developed by the author. All of these models can be distilled down to a single unique parameter {\xi}, here named the critical parameter, which was found to have values of 3 and 1.18 from the previous studies, and a value of 1.89 from the modified SCM. While still on the conservative side, this new model tends to better identify what structure is gravitationally bound in simulations. All three analytical models are applied to the Corona Borealis supercluster, with the modified SCM and {\xi} = 1.18 model making predictions that are in agreement with recent work showing that A2056, A2061, A2065, A2067, and A2089 comprise a gravitationally bound supercluster. As an additional test, the modified SCM is used to estimate the mass within the turn around radius of the Virgo cluster, providing results in good agreement with studies relating the virial mass of clusters to the total mass within turn around.
Doppler images and the underlying dynamo. The case of AF Leporis

The (Zeeman-)Doppler imaging studies of solar-type stars very often reveal large high-latitude spots. This also includes F stars that possess relatively shallow convection zones, indicating that the dynamo operating in these stars differs from the solar dynamo. We aim to determine whether mean-field dynamo models of late-F type dwarf stars can reproduce the surface features recovered in Doppler maps. In particular, we wish to test whether the models can reproduce the high-latitude spots observed on some F dwarfs. The photometric inversions and the surface temperature maps of AF Lep were obtained using the Occamian-approach inversion technique. Low signal-to-noise spectroscopic data were improved by applying the least-squares deconvolution method. The locations of strong magnetic flux in the stellar tachocline as well as the surface fields obtained from mean-field dynamo solutions were compared with the observed surface temperature maps. The photometric record of AF Lep reveals both long- and short-term variability. However, the current data set is too short for cycle-length estimates. From the photometry, we have determined the rotation period of the star to be 0.9660+-0.0023 days. The surface temperature maps show a dominant, but evolving, high-latitude (around +65 degrees) spot. Detailed study of the photometry reveals that sometimes the spot coverage varies only marginally over a long time, and at other times it varies rapidly. Of a suite of dynamo models, the model with a radiative interior rotating as fast as the convection zone at the equator delivered the highest compatibility with the obtained Doppler images.
Improved discovery of a nearly degenerate model: MUED using MT2 at the LHC

We study the discovery potential of the Minimal Universal Extra Dimension model (MUED) and improve it utilizing the multijet + lepton mode at the LHC. Since the MUED has a nearly degenerate spectrum, most events only have soft jets and small Emiss. The signature is challenging to search. We apply MT2 for the event selection and set the invisible particle mass of MT2 (test mass) to zero. The test mass is much smaller than the invisible particle mass of MUED. In that case, MT2 of the signal can be large depending on Up-Stream Radiations (USR) which includes initial state radiations (ISR). On the other hand, MT2 of the background is mainly below the top quark mass. Hence, the signal is extracted from the background in the high MT2 region. Since we use the leading jets for MT2, there is a combinatorics effect. We found the effect also enhances the signal to background ratio for high MT2. We perform a detailed simulation with the Matrix Element correction to the QCD radiations. The discovery potential of the MUED is improved by the MT2 cut, and especially, the improvement is significant for the most degenerate parameter we consider, {\Lambda}R = 10.
CHEMICAL EVOLUTION OF PROTOPLANETARY DISKS—THE EFFECTS OF VISCOUS ACCRETION, TURBULENT MIXING, AND DISK WINDS

We calculate the chemical evolution of protoplanetary disks considering radial viscous accretion, vertical turbulent mixing, and vertical disk winds. We study the effects on the disk chemical structure when different models for the formation of molecular hydrogen on dust grains are adopted. Our gas-phase chemistry is extracted from the UMIST Database for Astrochemistry (Rate06) to which we have added detailed gas–grain interactions. We use our chemical model results to generate synthetic near- and mid-infrared local thermodynamic equilibrium line emission spectra and compare these with recent Spitzer observations. Our results show that if H2 formation on warm grains is taken into consideration, the H2O and OH abundances in the disk surface increase significantly. We find that the radial accretion flow strongly influences the molecular abundances, with those in the cold midplane layers particularly affected. On the other hand, we show that diffusive turbulent mixing affects the disk chemistry in the warm molecular layers, influencing the line emission from the disk and subsequently improving agreement with observations. We find that NH3, CH3OH, C2H2, and sulfur-containing species are greatly enhanced by the inclusion of turbulent mixing. We demonstrate that disk winds potentially affect the disk chemistry and the resulting molecular line emission in a manner similar to that found when mixing is included.
Status of Astronomy in Namibia.

Astronomy plays a major role in the scientific landscape of Namibia and Southern Africa. Considerable progress has been achieved scientifically as well as in terms of human capacity development in the field. In all wavelength regimes accessible with ground-based instruments, the largest of those instruments are situated in Southern Africa: MeerKAT, the Southern African Large Telescope, and the High Energy Stereoscopic System. Because of the excellent observing conditions from Namibian soil, further large-scale projects such as the Cherenkov Telescope Array considered sites in Namibia and the Africa Millimetre Telescope will eventually be built there. Against this background, the current situation of astronomical research and education in Namibia is reviewed, focusing on optical, radio and gamma-ray astronomy and also including smaller scale projects. Further, the role of astronomy, with particular focus on developmental aspects in the African context is outlined and the progress in human capacity development is summarized.
On the influence of the companion star in Eta Carinae: 2D radiative transfer modeling of the ultraviolet and optical spectra

We present 2D radiative transfer modeling of the Eta Carinae binary system accounting for the presence of a wind-wind collision (WWC) cavity carved in the optically-thick wind of the primary star. By comparing synthetic line profiles with HST/STIS spectra obtained near apastron, we show that the WWC cavity has a strong influence on multi-wavelength diagnostics. This influence is regulated by the modification of the optical depth in the continuum and spectral lines. We find that H-alpha, H-beta, and Fe II lines are the most affected by the WWC cavity, since they form over a large volume of the primary wind. These spectral lines depend on latitude and azimuth since, according to the orientation of the cavity, different velocity regions of a spectral line are affected. For 2D models with orientation corresponding to orbital inclination angle 110deg < i < 140deg and longitude of periastron 210deg < omega < 330deg, the blueshifted and zero-velocity regions of the line profiles are the most affected. These orbital orientations are required to simultaneously fit the UV and optical spectrum of Eta Car, for a half-opening angle of the cavity in the range 50-70deg. We find that the excess P-Cygni absorption seen in H-alpha, H-beta and optical Fe II lines in spherical models becomes much weaker or absent in the 2D models, in agreement with the observations. The observed UV spectrum of Eta Car, dominated by Fe II absorption lines, is superbly reproduced by our 2D cavity models. Small discrepancies still remain, as H-gamma and H-delta absorptions are overestimated by our models. We suggest that photoionization of the wind of the primary by the hot companion star is responsible for the weak absorption seen in these lines. Our CMFGEN models indicate that the primary star has a mass-loss rate of 8.5x10e-4 Msun/yr and wind terminal velocity of 420 km/s around the 2000 apastron.
CORRELATIONS OF DISK AND JET EMISSION DEVIATING FROM THE FUNDAMENTAL PLANE

The variability of the accretion rate, which is believed to induce the aperiodic variability of X-ray emission from disks, may affect the energy injection into a jet. In this spirit, a correlation between disk emission and jet emission can be formed even if the mean luminosity of disk emission remains constant. In this work, these correlations are found in the situation in which the luminosity of disk emission is variable and kept at a constant mean value. The obtained correlations may be shallower than that of the fundamental plane of black hole activity. In addition, the slope of correlation may increase with increasing observed frequency of jet emission. For the luminosities spaced over three days, the slope of correlation decreases with increasing black hole mass. The deviation of our found correlations from that of the fundamental plane is related to the suppression of variability in the jet emission in comparison with that in the disk emission. This mechanism may work in some sources in which shallower correlations have been reported. Moreover, it implies that luminosities used to estimate the relation of the fundamental plane should cover an appropriate timescale, in which the variability of jet emission is not significantly suppressed.
High-redshift Fermi blazars observed by GROND and Swift

We observed 5 gamma-ray loud blazars at redshift greater than 2 with the X-Ray Telescope (XRT) and the UltraViolet and Optical Telescope (UVOT) onboard the Swift satellite, and the Gamma-Ray burst Optical Near-Infrared Detector (GROND) instrument. These observations were quasi simultaneous, usually within a few hours. For 4 of these blazars the near-IR to UV data show the presence of an accretion disc, and we could reliably estimate its accretion rate and black hole mass. One of them, PKS 1348+007, was found in an extraordinarily high IR-optical state, almost two orders of magnitude brighter than at the epoch of the Sloan Digital Sky Survey observations. For all the 5 quasars the physical parameters of the jet emitting zone, derived by applying a one-zone emission model, are similar to that found for the bulk of other gamma-ray loud quasars. With our observations we have X-ray data for the full sample of blazars at z>2 present in the Fermi 2-yrs (2LAC) catalog. This allows to have a rather complete view of the spectral energy distribution of all high-redshift Fermi blazars, and to draw some conclusions about their properties, and especially about the relation between the accretion rate and the jet power.
Implementation of Autonomous Cars using Machine Learning

In crowded countries like India, traffic problems are a big issue because of the large population. So, autonomous driving is becoming increasingly common and has the potential to disrupt our transportation system. In addition, self-driving cars are on their way to becoming legal, but they are still not safe enough to be used in the real world due to a lack of trust. The purpose of this survey is to describe an em-pirical study on the implementation of autonomous vehicles using machine learning algorithms. Different algorithms are used in the implementation of self-driving cars. Accuracy is used as the evaluation metric. Road Lane Detection, Support Vector Machine(SVM) for anomalies detection, and Disparity Map was used as the algorithms. From the experimental analysis, this research study has observed that these machine learning models have taken less time for processing images autonomously with model accuracies of 97% for road lane detection, and SVM has shown 98% of accuracy for anomaly detection. The proposed models have outperformed baseline models with a significant difference.
More on Gopakumar-Vafa formula: coefficients $\mathcal{F}_0$ and $\mathcal{F}_1$

In Type IIA compactified on a Calabi-Yau threefold, the genus zero and one terms of the Gopakumar-Vafa (GV) formula describe F-terms that are related to genus zero and one topological amplitudes. While for higher-genus terms $\mathcal{F}_g, g\ge 2$, the contribution of a light hypermultiplet can be computed via a sum over Kaluza-Klein harmonics, as has been shown in a recent paper, for $g \leq 1$, the sum diverges and it is better to compute $\mathcal{F}_0$ and $\mathcal{F}_1$ directly in five-dimensional field theory. Such a computation is presented here.
Automatic detection of covid-19 using CNN model combined with Firefly algorithm

Coronavirus has already been spread around the world, in many countries, and it has already claimed many lives. Further, the World Health Organization (WHO) has notified public health officials that COVID-19 has reached global epidemic status. Therefore, an early diagnosis using a chest CT scan can aid medical specialists in critical situations. This study aims to develop a web-based service for detecting COVID-19 online. To achieve our goal, we merged the convolutional neural network (CNN) model with the Firefly algorithm (FA). This combination ameliorate definitely the performance and efficiency of the CNN proposed model. Furthermore, the experiments revealed that the proposed FACNN framework enables us to reach high performance with regard to precision, accuracy, sensitivity, F-measure, recall and specificity (1.0%, 1.0%, 1.0%, 1.0%, 1.0% and 1.0%). In addition, a web-based interface was developed to identify and recogonize COVID-19 in chest radiographs in just few seconds. We anticipate that this web predictor will potentially save precious lives, and therefore contribute to society positively.
GLS Tracing: Gem5-based Low-intrusive Software Tracing

Profiling and tracing mechanisms are vital to identify performance bottlenecks for the optimization of modern multi-threaded applications [1]. While profiling generates a summary of averaged performance metrics, tracing provides a full record (trace) of timestamped events [1]. Hence, tracing is mandatory for detailed timing analysis but is usually difficult to implement. First, the generated traces can get large which usually results in a high overhead to record them. Second, lossless traces (no events get lost) with precise timestamps for correct event ordering across large multi-core systems are challenges for common tracing mechanisms. As a complementary approach to existing tracing mechanisms, we introduce GLS Tracing (Gem5-based Low-intrusive Software Tracing), which overcomes the mentioned challenges. GLS Tracing combines the flexibility and fine granular resolution of software tracepoints (TP) with the low-intrusive system analysis capabilities of the Gem5 simulator. Using new Gem5 pseudo-instructions (Trace Point Operation, TPOP), the time-consuming recording of a native TP in software tracing is offloaded to the Gem5 Full-System simulator, thus reducing the number of CPU cycles to be simulated for this tracing. This new tracing capability is integrated into the native Linux kernel software TP infrastructure TRACE_EVENT, resulting in an average overhead reduction of 93% per recorded TP (from on average 2300 clock cycles down to 160 clock cycles). In addition, a less flexible but almost non-intrusive TP is defined that adds only 5 to 10 cycles overhead per TP. This provides a lossless low-intrusive tracing solution for Gem5, which can be used in both user-space and kernel-space functions.
Strong suppression of star formation and spiral arm formation in disk galaxies with counter-rotating gas disks

Galaxy-wide star formation can be quenched by a number of physical processes such as environmental effects (e.g., ram pressure stripping) and supernova feedback. Using numerical simulations, we here demonstrate that star formation can be severely suppressed in disk galaxies with their gas disks counter-rotating with respect to their stellar disks. This new mechanism of star formation suppression (or quenching) does not depend so strongly on model parameters of disk galaxies, such as bulge-to-disk- ratios and gas mass fractions. Such severe suppression of star formation is due largely to the suppression of the gas density enhancing mechanism i.e spiral arm formation in disk galaxies with counter-rotating gas. Our simulations also show that molecular hydrogen and dust can be rather slowly consumed by star formation in disk galaxies with counter-rotating gas disks (i.e., long gas depletion timescale). Based on these results, we suggest that spiral and S0 galaxies with counter-rotation can have rather low star formation rate for their gas densities. Also we suggest that a minor fraction of S0 galaxies have no prominent spiral arms, because they have a higher fraction of counter-rotating gas. We predict that poststarburst E+A disk galaxies with cold gas could have counter-rotating gas.
Modeling, Design, and Control of the Parallel-Series Compensated Bidirectional IPT Topology for EV Applications

This paper addresses the bidirectional power flow capability of the current-fed inductive power transfer (IPT) converter. The proposed bi-directional IPT converter has Parallel-Series (P-S) topology during grid-to-vehicle (G2V) and Series-Parallel (S-P) topology during vehicle-to-grid (V2G) mode of operation. Mathematical modeling of both topologies is included that provides the detailed analysis of the converter. The selection of circuit parameters is made for the conventional mode of operation, G2V mode. The bidirectional power flow of the converter is controlled to meet the load requirements. The small-signal modeling and circuit frequency responses are also reported for both modes of operation. The viability of the technique is verified through the simulation results of the PowerSIM simulation platform.
Strong multifield slowroll condition and spiral inflation

We point out the existing confusions about the slowroll parameters and conditions for multifield inflation. If one requires the fields to roll down the gradient flow, we find that only articles adopting the Hubble slowroll expansion are on the right track, and a correct condition can be found in a recent book by Liddle and Lyth. We further analyze this condition and show that the gradient flow requirement is stronger than just asking for a slowly changing, quasi-de Sitter solution. Therefore it is possible to have a multifield slowroll model that does not follow the gradient flow. Consequently, it no longer requires the gradient to be small. It even bypasses the first slowroll condition and some related no-go theorems from string theory. We provide the "spiral inflation" as a generic blueprint of such inflation model and show that it relies on a monodromy locus---a common structure in string theory effective potentials.
Higher-order symmetry-protected topological states for interacting bosons and fermions

Higher-order topological insulators have a modified bulk-boundary correspondence compared to other topological phases: instead of gapless edge or surface states, they have gapped edges and surfaces, but protected modes at corners or hinges. Here, we explore symmetry-protected topological phases in strongly interacting many-body systems with this generalized bulk-boundary correspondence. We introduce several exactly solvable bosonic lattice models as candidates for interacting higher-order symmetry-protected topological (HOSPT) phases protected by spatial symmetries, and develop a topological field theory that captures the nontrivial nature of the gapless corner and hinge modes. We show how, for rotational symmetry, this field theory leads to a natural relationship between HOSPT phases and conventional SPT phases with an enlarged internal symmetry group. We also explore the connection between bosonic and fermionic HOSPT phases in the presence of strong interactions, and comment on the implications of this connection for the classification of interacting fermionic HOSPT phases. Finally, we explore how gauging internal symmetries of these phases leads to topological orders characterized by nontrivial braiding statistics between topological vortex excitations and geometrical defects related to the spatial symmetry.