Miracle-dz/UniFAR-FTUs huggingface dataset:
Discovery of an old nova shell surrounding the cataclysmic variable V1315 Aql

Following our tentative discovery of a faint shell around V1315 Aql reported in Sahman et al., we undertook deep Hα imaging and intermediate-resolution spectroscopy of the shell. We find that the shell has its geometric centre located on V1315 Aql. The mass, spectral features, and density of the shell are consistent with other nova shells, rather than planetary nebulae or supernova remnants. The radial velocity of the shell is consistent with the systemic velocity of V1315 Aql. We believe this evidence strongly suggests that the shell originates from an earlier nova event. This is the first nova shell discovered around a nova-like and supports the theory of nova-induced cycles in mass transfer rates (hibernation theory) first proposed by Shara et al.
Gravitational instability: An Approximate theory for large density perturbations

An approximate solution is given for the problem of the growth of perturbations during the expansion of matter without pressure. The solution is qualitatively correct even when the perturbations are not small. Infinite density is first obtained on disc-like surfaces by unilateral compression. The following layers are compressed first adiabatically and then by a shook wave. Physical conditions in the compressed matter are analysed.
Significance of the largest scale CMB fluctuations in WMAP

We investigate anomalies reported in the Cosmic Microwave Background maps from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite on very large angular scales and discuss possible interpretations. Three independent anomalies involve the quadrupole and octopole: 1. The cosmic quadrupole on its own is anomalous at the 1-in-20 level by being low (the cut-sky quadrupole measured by the WMAP team is more strikingly low, apparently due to a coincidence in the orientation of our Galaxy of no cosmological significance); 2. The cosmic octopole on its own is anomalous at the 1-in-20 level by being very planar; 3. The alignment between the quadrupole and octopole is anomalous at the 1-in-60 level. Although the a priori chance of all three occurring is 1 in 24000, the multitude of alternative anomalies one could have looked for dilutes the significance of such a posteriori statistics. The simplest small universe model where the universe has toroidal topology with one small dimension of order half the horizon scale, in the direction towards Virgo, could explain the three items above. However, we rule this model out using two topological tests: the S-statistic and the matched circle test.
Sub-radian-accuracy gravitational waveforms of coalescing binary neutron stars in numerical relativity

Extending our previous studies, we perform high-resolution simulations of inspiraling binary neutron stars in numerical relativity. We thoroughly carry through a convergence study in our currently available computational resources with the smallest grid spacing of $\ensuremath{\approx}63--86$ meter for the neutron-star radius 10.9--13.7 km. The estimated total error in the gravitational-wave phase is of order 0.1 rad for the total phase of $\ensuremath{\gtrsim}210\text{ }\text{ }\mathrm{rad}$ in the last $\ensuremath{\sim}15--16$ inspiral orbits. We then compare the waveforms (without resolution extrapolation) with those calculated by the latest effective-one-body formalism (tidal SEOBv2 model referred to as TEOB model). We find that for any of our models of binary neutron stars, the waveforms calculated by the TEOB formalism agree with the numerical-relativity waveforms up to $\ensuremath{\approx}3\text{ }\text{ }\mathrm{ms}$ before the peak of the gravitational-wave amplitude is reached: For this late inspiral stage, the total phase error is $\ensuremath{\lesssim}0.1\text{ }\text{ }\mathrm{rad}$. Although the gravitational waveforms have an inspiral-type feature for the last $\ensuremath{\sim}3\text{ }\text{ }\mathrm{ms}$, this stage cannot be well reproduced by the current TEOB formalism, in particular, for neutron stars with large tidal deformability (i.e., lager radius). The reason for this is described.
Individual low-energy E1 toroidal and compression states in light nuclei: deformation effect, spectroscopy and interpretation

The existence of individual low-energy E1 toroidal and compression states (TS and CS) in $^{24}$Mg was predicted recently in the framework of quasiparticle random-phase-approximation (QRPA) model with Skyrme forces. It was shown that the strong axial deformation of $^{24}$Mg is crucial to downshift the toroidal strength to the low-energy region and thus make the TS the lowest E1(K=1) dipole state. In this study, we explain this result by simple mean-field arguments. Comparing TS in two strongly axial nuclei, $^{24}$Mg and $^{20}$Ne, we show that the lowest TS is not not a universal phenomenon but rather a peculiarity of $^{24}$Mg. The spectroscopy of TS and CS is analyzed and some additional interpretation of these states is suggested.
The Hour-timescale GeV Flares of PSR B1259–63 in 2017

GeV flares from PSR B1259−63/LS 2883 were seen starting around 30 days after the two periastron passages in 2010 and 2014. The flares are clearly delayed compared to the occurrence of the X-ray and TeV flux peaks during the post-periastron disk crossing. Although several attempts have been put forward to explain this phenomenon, the origin of these GeV flares remains a puzzle. Here we present a detailed analysis of the observational data taken by the Fermi and Swift observatories over the 2017 September periastron passage. For the first time, we find short-lived but powerful GeV flares on timescales of down to three hours. The onset of the GeV flaring period in 2017 is also delayed compared to that seen in 2011 and 2014. Supplemented by a reanalysis of previous data, we compare the Fermi/LAT, Swift/XRT, and Swift/UVOT light curves in 2017 with those taken over the 2010 and 2014 periastrons, and differences in UVOT light curves are noted.
RXJ1856.5-3754 and RXJ0720.4-3125 are P-stars

P-stars are a new class of compact stars made of up and down quarks in β-equilibrium with electrons in a chromomagnetic condensate. P-stars are able to account for compact stars with R6 km, as well as stars comparable to canonical neutron stars. We show that P-stars once formed are absolutely stable, for they cannot decay into neutron or strange stars. We convincingly argue that the nearest isolated compact stars RXJ1856.5-3754 and RXJ0720.4-3125 could be interpreted as P-stars with M0.8 M⊙ and R 5 km.
Finite action in 5D gauged supergravity and the dilatonic conformal anomaly for dual quantum field theory

Gauged supergravity (SG) with single scalar (dilaton) and arbitrary scalar potential is considered. Such dilatonic gravity describes special RG flows in extended SG where scalars lie in one-dimensional submanifold of total space. The surface counterterm and finite action for such gauged SG in three-, four- and five-dimensional asymptotically AdS space are derived. Using finite action and consistent gravitational stress tensor (local surface counterterm prescription) the regularized expressions for free energy, entropy and mass of d4 dilatonic AdS black hole are found. The same calculation is done within standard reference background subtraction. The dilaton-dependent conformal anomaly from d3 and d5 gauged SGs is calculated using AdS/CFT correspondence. Such anomaly should correspond to two- and four-dimensional dual quantum field theory which is classically (not exactly) conformally invariant, respectively. The candidate c-functions from d3 and d5 SGs are suggested. These c-functions which have fixed points in asymptoticaly AdS region are expressed in terms of dilatonic potential and they are positively defined and monotonic for number of potentials.
Comparison between square, triangular, or one dimensional lattice of distortions in smectic A and cholesteric crystals for superposed strain and magnetic field of any directions

We study the conditions of observations of a static periodic square grid or lattice of distortions in cholesteric of smectic A liquid crystals under a static magnetic field or fast tensile strain. We show that a square lattice is energetically favorable with respect to other lattices. With a tilted magnetic field H we expect two threshold fields: (a) a one dimensional distortion threshold field H1 and (b) a two dimensional square distortion field H2>H1. H1 and H2 are function of the angle θ of H with the normal to the layers. There exists only a one dimensional solution for θ>30°.
Following the Kondo temperature of a tunable single-molecule junction continuously from the Kondo singlet to the free spin 1/2 ground state.

We monitor the conductance evolution by varying the coupling between an organic molecule and the Ag(111) surface by lifting the molecule from the surface with the tip of a scanning tunneling microscope. Numerical renormalization group theory analysis of the junction conductance reveals that the system is tuned from the strongly coupled Kondo singlet to the free spin 1/2 ground state. In the crossover between the strong and weak coupling regimes, where the Kondo temperature $T_K$ is similar to the experimental $T_{\rm exp}$, fitting procedures generically provide ambiguous estimates of $T_{\rm K}$ that tend to vary by an order of magnitude. Measuring the dependence of the junction conductance in external magnetic fields resolves this ambiguity if the Zeeman splitting due to the imposed magnetic field overcomes the thermal energy $k_BT_{\rm exp}$. We demonstrate that Frota analysis overestimates $T_{\rm K}$ by several orders of magnitude in the transient and weak coupling regimes. The numerical analysis also allows us to determine molecular coupling to surface and tip and their evolution during the lifting process.
A Scaling Law for Interstellar Depletions

An analytical expression is presented that allows gas-to-dust elemental depletions to be estimated in interstellar environments of different types, including damped Lyα systems, by scaling an arbitrary depletion pattern chosen as a reference. As an improvement on previous work, the scaling relation allows the dust chemical composition to vary and includes a set of parameters which describe how sensitive the dust composition is to changes in both the dust-to-metals ratio and the composition of the medium. These parameters can be estimated empirically from studies of Galactic and extragalactic depletion patterns. The scaling law is able to fit all the typical depletion patterns of the Milky Way ISM (cold disk, warm disk, and warm halo) with a single set of parameters by only varying the dust-to-metals ratio. The dependence of the scaling law on the abundances of the medium has been tested using interstellar observations of the Small Magellanic Cloud (SMC), for which peculiar depletion patterns have been reported in the literature. The scaling law is able to fit these depletion patterns, assuming that the SMC relative abundances are slightly nonsolar.
Constraints on primordial non-Gaussianity from future Hi intensity mapping experiments

The primordial non-Gaussianity induces scale-dependent bias of the Hi with respect to the underlying dark matter, which exhibits features on the very large scale of the 21-cm power spectrum potentially observable with Hi intensity mapping observations. We forecast the prospective constraints on the four fundamental shapes of primordial non-Gaussianity (local, equilateral, orthogonal, and enfolded), with the current and future Hi intensity mapping experiments, BINGO, FAST, and SKA-I. With the current configuration of the experiments and assumed one-year observation time, we find that the SKA-I will provide tighter constraints on the local shape of primoridal non-Gaussianity than Planck. The results are $({\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\text{local}}},{\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\text{equil}}},{\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\mathrm{orth}}},{\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\text{enfold}}}{)}_{\text{SKA-I}}=(0.54,86,25,43)$, $({\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\text{local}}},{\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\text{equil}}},{\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\mathrm{orth}}},{\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\text{enfold}}}{)}_{\mathrm{BINGO}}=(17,100,128,164)$, $({\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\text{local}}},{\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\text{equil}}},{\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\mathrm{orth}}},{\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}^{\text{enfold}}}{)}_{\mathrm{FAST}}=(9.5,44,75,94)$. If the lower frequency band of FAST can be used, the constraint on local-type primordial non-Gaussianity will be ${\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}}\ensuremath{\sim}1.62$ which is better than Planck. In addition, if the observation time for FAST could be extended to two years, the constraint on the equilateral shape of primordial non-Gaussianity would be improved to ${\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}}\ensuremath{\sim}32$. Similarly, if the observational time of SKA-I could be extended to two years, the constraint on local and orthogonal shapes could be improved to 0.43 and 20, respectively, achieving better constraints than Planck.
Parallel and series conduction model in Topological Insulators

In the past few years there has been a surge in the material science engineering in order to synthesize bulk insulating and surface metallic Topological Insulating (TI) materials. This quest is not only theoretically important but also promising from the novel application perspective. The dependence of temperature on resistance (R-T) of a particular sample reveals a plethora of information about the electronic properties especially in a unique sample like TI where there are two components comprising of an insulating bulk and metallic surface states. Depending on the amount of intrinsic doping during the sample formation, the bulk can either couple or remain decoupled with the surface. The former leads to a metallic R-T profile whereas the latter is captured by an insulating R-T behavior. These two behaviors can be represented by series and parallel resistor models respectively. In this work we study the R-T behavior in the framework of resistor models capturing the essential features of our sample.
Path Coalescence in Spatially Correlated Random Walks

A particle subject to successive, random displacements is said to execute a random walk (in position or some other coordinate). The mathematical properties of random walks have been very thoroughly investigated, and the model is used in many areas of science and engineering as well as other fields such as finance and the life sciences. This letter describes a phenomenon occurring in a natural extension of this model: we consider the motion of a large number of particles subject to successive random displacements which are correlated in space, but not in time. If these random displacements are smaller than their correlation length, the trajectories coalesce onto a decreasing number of trails. This surprising effect is explained and quantitative results are obtained. Various possible realisations are discussed, ranging from coalescence of the tracks of water droplets blown off a windshield to migration patterns of animals.
Mg ii Absorbers: Metallicity Evolution and Cloud Morphology

Metal abundance and its evolution are studied for Mg ii quasar absorption line systems from their weak, unsaturated spectral lines using stacked spectra from the archived data of the Sloan Digital Sky Survey. They show an abundance pattern that resembles that of the Galactic halo or Small Magellanic Cloud, with metallicity [Z/H] showing an evolution from redshift z = 2 to 0.5: metallicity becomes approximately solar or even larger at . We show that the evolution of the metal abundance traces the cumulative amount of the hydrogen fuel consumed in star formation in galaxies. With the aid of a spectroscopic simulation code, we infer the median gas density of the cloud to be roughly 0.3 , with which the elemental abundance in various ionization stages, in particular C i, is consistently explained. This gas density implies that the size of the Mg ii clouds is of the order of 0.03 kpc, which suggests that individual Mg ii clouds around a galaxy are of a baryonic mass typically . This means that Mg ii clouds are numerous and “foamy,” rather than a large entity that covers a sizable fraction of galaxies with a single cloud.
Set Orderings Requiring Costliest Alphabetic Binary Trees

It is shown that an ordering of a set with weighted elements which requires the most expensive alphabetic binary tree is a “sawtooth order. ” For the set $\{ e_0 ,e_1 , \cdots ,e_t \}$, with the elements indexed from least to greatest weight, this order is $e_0 ,e_t ,e_1 ,e_{t - 1} , \cdots ,e_j ,e_{t - 1} , \cdots $. This result was conjectured by Hwang and leads to an upper bound on the cost of alphabetic binary trees.
Comparison of electromagnetic interference shielding properties between single-wall carbon nanotube and graphene sheet/polyaniline composites

Single-wall carbon nanotube/polyaniline (SWCNT/PANI) and graphene sheet/polyaniline (GS/PANI) composites were prepared by a simple alcohol-assisted dispersion and pressing process. The SWCNTs and GSs were synthesized by the dc arc-discharge method. The dc electrical conductivity and the electromagnetic interference (EMI) shielding effectiveness (SE) of these two kinds of composites were measured. The experimental results reveal that the conductivity and the EMI SE of the GS/PANI composite are better than that of the SWCNT/PANI composite, and the absorption proportion of the SWCNT/PANI composite is higher than that of the GS/PANI composite. The EMI shielding results (2–18 GHz) also show that both composites present an absorption-dominant mechanism and present a wide application prospect in the field of EMI shielding and microwave absorption.
On the charge of the Galactic centre black hole

The Galactic centre supermassive black hole (SMBH), in sharp contrast with its complex environment, is characterized by only three classical parameters -- mass, spin, and electric charge. Its charge is poorly constrained. It is, however, usually assumed to be zero because of neutralization due to the presence of plasma. We revisit the question of the SMBH charge and put realistic limits on its value, timescales of charging and discharging, and observable consequences of the potential, small charge associated with the Galactic centre black hole. The electric charge due to classical arguments based on the mass difference between protons and electrons is $\lesssim 10^9\,{\rm C}$ and is of a transient nature on the viscous time-scale. However, the rotation of a black hole in magnetic field generates electric field due to the twisting of magnetic field lines. This electric field can be associated with induced charge, for which we estimate an upper limit of $\lesssim 10^{15}\,{\rm C}$. Moreover, this charge is most likely positive due to an expected alignment between the magnetic field and the black-hole spin. Even a small charge of this order significantly shifts the position of the innermost stable circular orbit (ISCO) of charged particles. In addition, we propose a novel observational test based on the presence of the bremsstrahlung surface brightness decrease, which is more sensitive for smaller unshielded electric charges than the black-hole shadow size. Based on this test, the current upper observational limit on the charge of Sgr A* is $\lesssim 3\times 10^{8}\,{\rm C}$.
TopC-CAMF: Sistem Perekomendasi Matrix Factorization Berbasis Top Context

Intisari—Aktivitas daring menjadi makin vital seiring dengan berkembangnya bisnis digital. Pengguna dapat melakukan sebagian besar aktivitas daring seperti belanja, pemesanan hotel, atau pendidikan dan kursus daring. Sejumlah besar pengguna media sosial tertarik pada banyaknya barang yang tersedia di internet. Banyaknya informasi membuat pengguna sosial tidak mungkin memilih informasi tersebut dengan benar dan efisien. Banyak perusahaan menawarkan personalisasi untuk mengatasi masalah ini. Terbukti bahwa sistem rekomendasi yang dipersonalisasi mampu menyarankan barang kepada pengguna berdasarkan minat dan kebutuhan yang paling sesuai kepada setiap pengguna dengan menggunakan informasi kontekstual pengguna. Namun, sebagian besar riset menangkap informasi kontekstual ini dari konteks yang telah ditentukan, seperti lokasi dan waktu. Dalam riset ini, diperoleh konteks pengguna yang dipersonalisasi dari ulasan teks pengguna yang dituliskan pengguna memberi peringkat pada suatu barang. Untuk tujuan ini, diusulkan pendekatan baru berdasarkan rekomendasi matrix factorization (MF), TopC-CAMF, yang menyelidiki dan menemukan konteks atau kebutuhan paling penting untuk setiap pengguna dengan memanfaatkan model pembelajaran mendalam. Pertama, semua konteks penting dari ulasan teks pengguna diekstrak. Kemudian, preferensi pengguna direpresentasikan dengan variasi konteks yang paling penting, yaitu konteks top 5, top 10, top 15, top 20, dan top 25. Kemudian, variasi top konteks terbaik dievaluasi dan top konteks yang teroptimal digunakan sebagai masukan untuk metode MF dalam memberikan rekomendasi yang lebih baik. Eksperimen ekstensif menggunakan tiga kumpulan data nyata dilakukan untuk membuktikan efektivitas TopC-CAMF dengan metrik root mean square error (RMSE), mean absolute error (MAE), mean squared error (MSE), normalized discounted cumulative gain (NDCG), dan recall.
On the Age of the TRAPPIST-1 System

The nearby (d = 12 pc) M8 dwarf star TRAPPIST-1 (2MASS J23062928−0502285) hosts a compact system of at least seven exoplanets with sizes similar to Earth. Given its importance for testing planet formation and evolution theories, and for assessing the prospects for habitability among Earth-size exoplanets orbiting the most common type of star in the Galaxy, we present a comprehensive assessment of the age of this system. We collate empirical age constraints based on the color-absolute magnitude diagram, average density, lithium absorption, surface gravity features, metallicity, kinematics, rotation, and magnetic activity; and conclude that TRAPPIST-1 is a transitional thin/thick disk star with an age of 7.6 ± 2.2 Gyr. The star’s color–magnitude position indicates that it is slightly metal-rich, which is consistent with the previously reported near-infrared spectroscopic metallicity; and it has a radius ) that is larger by 8%–14% than the predictions of solar-metallicity evolutionary models. We discuss some implications of the old age of this system with regard to the stability and habitability of its planets.
CP violation in $D^0 \to K^+ \pi^- $

In this paper we study the direct CP asymmetry of the doubly Cabibbo-suppressed decay mode $D^0 \to K^+ \pi^- $ within standard model and two Higgs doublet model with generic Yukawa structure. In the standard model we derive the corrections to the tree level amplitude, generated from the box and di-penguin diagrams, required for generating the weak CP violating phases. We show that these phases are so tiny leading to a direct CP asymmetry of order $10^{-9}$. Regarding the two Higgs doublet model with generic Yukawa structure we derive the Wilson coefficients relevant to $D^0 \to K^+ \pi^- $. After taking into account all constraints on the parameter space of the model we show that charged Higgs couplings to quarks can lead to a direct CP asymmetry of order $10^{-3}$ which is $6$ orders of magnitude larger than the standard model prediction.