ShantanuT01/DACTYL-Pretraining huggingface dataset:
The differential rotation of the solar corona for the period 1976-2004 was studied as a function of the distance from the center of the Sun. For this study, we developed a method using the coronal magnetic field as a tracer. The field in a spherical layer from the base of the corona up to the source surface was determined from photospheric measurements. Calculations were performed for 14 heliocentric distances from the base of the corona up to 2.45 solar radii and from the equator to about 75 degrees of latitude at 5 degrees steps. For each day, we calculated three components, which were then used to obtain the field strength. The coronal rotation periods were determined by the periodogram method for all distances and latitudes under consideration. The variations in the coronal rotation during the time interval 1976-2004 were as follows: the gradient of differential rotation decreased with the increase of heliocentric distance; the rotation remaining differential even in the vicinity of the source surface. The largest rotation rates were recorded at the cycle minimum at small heights in the corona. The lowest rotation rate was observed at the middle of the ascending branch at large distances. At the minimum of the cycle, the differential rotation is most clearly pronounced, especially at small heliocentric distances. As the distance increases, the differential gradient decreases in all phases. The results based on magnetic data and on the brightness of the coronal green line 530.3nm FeXIV used earlier show a satisfactory agreement. Since the rotation of the magnetic field at the corresponding heights in the corona is probably determined by the conditions in the field generation region, an opportunity arises to use this method for diagnostics of differential rotation in the subphotospheric layers.
Uncertainty principle has a fundamental role in quantum theory. This principle states that it is not possible to measure two incompatible observers simultaneously. The uncertainty principle is expressed logically in terms of standard deviation of the measured observables. In quantum information it has been shown that the uncertainty principle can be expressed by means of Shannon's entropy. Entropic uncertainty relation can be improve by consider an additional particle as the quantum memory. In the presence of quantum memory the entropic uncertainty relation is called quantum memory assisted entropic uncertainty relation. In this work we will consider the case in which the quantum memory moves inside the leaky cavity. We will show that by increasing the velocity of the quantum memory the entropic uncertainty lower bound decreased.
Applying the Lyapunov-Schmidt reduction approach introduced by Mielke and Schneider in their analysis of the fourth-order scalar Swift-Hohenberg equation, we carry out a rigorous small-amplitude stability analysis of Turing patterns for the canonical second-order system of reaction diffusion equations given by the Brusselator model. Our results confirm that stability is accurately predicted in the small-amplitude limit by the formal Ginzburg Landau amplitude equations, rigorously validating the standard weakly unstable approximation and Eckhaus criterion.
We calculate the amplitude for a non-excited closed string with nonzero winding number to scatter from a D-string with a near critical E field. We go to the NCOS limit and observe that we get the same result if we adopt another approach put forward by Gomis and Ooguri.
We construct hybrid binary black holes merger waveforms using analytical model waveforms for the early inspiral phase and numerical relativity waveforms for late inspiral to merger and post merger phases. To hybridize analytical and numerical waveforms, we first perform a 3-dimensional rotation to align the instantaneous orbital planes associated with the two waveforms at some fiducial frequency, we then find appropriate phase and time translations that maximize the overlap of the two waveforms in a hybridization interval. We discuss the accuracy and limitations for hybrids constructed by this procedure in the context of LIGO-Virgo-KAGRA observations. Our goal is to hybridize waveforms for more generic precessing binaries and construct longer waveforms that are sufficiently accurate for the parameter estimation techniques for upcoming LIGO observations.
In anticipation of a subsequent application to QCD, we consider the case of QED at high temperature. We introduce a Fradkin representation into the exact, Schwingerian, functional expression of a fermion propagator, as well as a new and relevant version of the Bloch-Nordsieck (BN) model, which extracts the soft contributions of every perturbative graph, in contradistinction to the assumed separation of energy scales of previous semi-perturbative treatments. Our results are applicable to the absorption of a fast particle which enters a heat bath, as well as to the propagation of a symmetric pulse within the thermal medium due to the appearance of an instantaneous, shock-wave-like source acting in the medium. An exponentially-decreasing time dependence of the incident particle's initial momentum combines with a stronger decrease in the particle's energy, estimated by a sum over all Matsubara frequencies, to model an initial "fireball", which subsequently decays in a Gaussian fashion. When extended to QCD, qualitative applications could be made to RHIC scattering, in which a fireball appears, expands and is damped away.
Mermin suggests comparing my recent proof of quantum nonlocality to Bohr's reply to Einstein, Podolsky, and Rosen. Doing so leads naturally to the insight that the nonlocal influence deduced from the analysis of the Hardy experiment is the same as the nonlocal influence deduced by Bohr, and used by him to block the application of the criterion of physical reality proposed by Einstein, Podolsky, and Rosen. However, the greater sophistication of the Hardy experiment, as contrasted to the experiment considered by Bohr and the three authors, exposes more clearly than before the nature of this influence, and thereby strengthens Bohr's position.
We analyze the spin-orbit coupling term in the nuclear energy density functional in terms of a zero-range NN-contact interaction and finite-range contributions from two-pion exchange. We show that the strength of the spin-orbit contact interaction as extracted from high-precision nucleon-nucleon potentials is in perfect agreement with that of phenomenological Skyrme forces employed in non-relativistic nuclear structure calculations. Additional long-range contributions from chiral two-pion exchange turn out to be relatively small. These explicitly density-dependent contributions reduce the ratio of the isovector to the isoscalar spin-orbit strength significantly below the Skyrme value 1/3. We perform a similar analysis for the strength function of the $(\vec \nabla \rho)^2$-term and find values not far from those of phenomenological Skyrme parameterizations.
Recent developments on the final state of a gravitationally collapsing massive matter cloud are summarized and reviewed here. After a brief background on the problem, we point out how the black hole and naked singularity end states arise naturally in spherical collapse. We see that it is the geometry of trapped surfaces that governs this phenomena.
Optical, near-infrared (NIR) photometric and spectroscopic studies, along with the optical imaging polarimetric results for SN 2012au, are presented in this article to constrain the nature of the progenitor and other properties. Well-calibrated multiband optical photometric data (from $-$0.2 to +413 d since $B$-band maximum) were used to compute the bolometric light curve and to perform semi-analytical light-curve modelling using the $\texttt{MINIM}$ code. A spin-down millisecond magnetar-powered model explains the observed photometric evolution of SN 2012au reasonably. Early-time imaging polarimetric follow-up observations ($-$2 to +31 d) and comparison with other similar cases indicate signatures of asphericity in the ejecta. Good spectral coverage of SN 2012au (from $-$5 to +391 d) allows us to trace the evolution of layers of SN ejecta in detail. SN 2012au exhibits higher line velocities in comparison with other SNe Ib. Late nebular phase spectra of SN 2012au indicate a Wolf$-$Rayet star as the possible progenitor for SN 2012au, with oxygen, He-core, and main-sequence masses of $\sim$1.62 $\pm$ 0.15 M$_\odot$, $\sim$4$-$8 M$_\odot$, and $\sim$17$-$25 M$_\odot$, respectively. There is a clear absence of a first overtone of carbon monoxide (CO) features up to +319 d in the $K$-band region of the NIR spectra. Overall analysis suggests that SN 2012au is one of the most luminous slow-decaying Type Ib SNe, having comparatively higher ejecta mass ($\sim$4.7$-$8.3 M$_\odot$) and kinetic energy ($\sim$[4.8 $-$ 5.4] $\times$ 10$^{51}$ erg). Detailed modelling using $\texttt{MESA}$ and the results obtained through $\texttt{STELLA}$ and $\texttt{SNEC}$ explosions also strongly support spin-down of a magnetar with mass of around 20 M$_\odot$ and metallicity Z = 0.04 as a possible powering source of SN 2012au.
The electronic structure of artificial Mn atom arrays on Ag(111) is characterized in detail with scanning tunnelling spectroscopy and spectroscopic imaging at low temperature. We demonstrate the degree to which variations in geometry may be used to control spatial and spectral distributions of surface state electrons confined within the arrays, how these are influenced by atoms placed within the structure and how the ability to induce spectral features at specific energies may be exploited through lineshape analyses to deduce quasiparticle lifetimes near the Fermi level. Through extensive comparison of $dI/dV$ maps and spectra we demonstrate the utility of a model based upon two-dimensional s-wave scatterers for describing and predicting the characteristics of specific resonators.
Using x-ray magnetic circular dichroism (XMCD), we determine the element-specific character and polarization of unoccupied states near the Fermi level in (Ga,Mn)As and (In,Ga,Mn)As thin films. The XMCD at the As K absorption edge consists of a single peak located on the low-energy side of the edge, which increases with the concentration of ferromagnetic Mn moments. The XMCD at the Mn K edge is more detailed and is strongly concentration-dependent, which is interpreted as a signature of hole localization for low Mn doping. The results indicate a markedly different character of the polarized holes in low-doped insulating and high-doped metallic films, with a transfer of the hole orbital magnetic moment from Mn to As sites on crossing the metal-insulator transition.
Few-shot learning (FSL) aims to learn a classifier that can be easily adapted to accommodate new tasks not seen during training, given only a few examples. To handle the limited-data problem in few-shot regimes, recent methods tend to collectively use a set of local features to densely represent an image instead of using a mixed global feature. They generally explore a unidirectional query-to-support paradigm in FSL, e.g., find the nearest/optimal support feature for each query feature and aggregate these local matches for a joint classification. In this paper, we propose a new method Mutual Centralized Learning (MCL) to fully affiliate the two disjoint sets of dense features in a bidirectional paradigm. We associate each local feature with a particle that can bidirectionally random walk in a discrete feature space by the affiliations. To estimate the class probability, we propose the features' accessibility that measures the expected number of visits to the support features of that class in a Markov process. We relate our method to learning a centrality on an affiliation network and demonstrate its capability to be plugged in existing methods by highlighting centralized local features. Experiments show that our method achieves the state-of-the-art on both miniImageNet and tieredImageNet.
Demonstration of non-Abelian anyon statistics often requires dynamical controls of a complicated device that are challenging in realistic situations. We propose a {\it single} Josephson junction to detect a non-Abelian statistics effect of Majorana fermions, formed by two finite-size $s$-wave superconductors on a topological insulator under a magnetic field. At certain field strengths, a train of three localized Majorana fermions appears along the junction, while an extended chiral Majorana fermion encircles the train and the superconductors. A DC voltage bias across the junction causes the train to move and collide with the extended Majorana fermion. This involves interchange of fusion partners among the four Majorana fermions, leading to non-Abelian state evolution. The evolution gives rise to a $2n\pi$ fractional AC Josephson effect with an arbitrary integer $n\ge2$ tunable by the voltage.
It has been proposed that a certain Z_N orbifold, analytically continued in N, can be used to describe the thermodynamics of Rindler space in string theory. In this paper, we attempt to implement this idea for the open-string sector. The most interesting result is that, although the orbifold is tachyonic for positive integer N, the tachyon seems to disappear after analytic continuation to the region that is appropriate for computing ${\mathrm {Tr}} \rho^{\mathcal N}$, where $\rho$ is the density matrix of Rindler space and Re $\mathcal N$>1. Analytic continuation of the full orbifold conformal field theory remains a challenge, but we find some evidence that if such analytic continuation is possible, the resulting theory is a logarithmic conformal field theory, necessarily nonunitary.
The construction of the effective Lagrangian relevant for the mesonic sector of QCD in the large N_c limit meets with a few rather subtle problems. We thoroughly examine these and show that, if the variables of the effective theory are chosen suitably, the known large N_c counting rules of QCD can unambiguously be translated into corresponding counting rules for the effective coupling constants. As an application, we demonstrate that the Kaplan-Manohar transformation is in conflict with these rules and is suppressed to all orders in 1/N_c. The anomalous dimension of the axial singlet current generates an additional complication: The corresponding external field undergoes nonmultiplicative renormalization. As a consequence, the Wess-Zumino-Witten term, which accounts for the U(3)_R x U(3)_L anomalies in the framework of the effective theory, contains pieces that depend on the running scale of QCD. The effect only shows up at nonleading order in 1/N_c, but requires specific unnatural parity contributions in the effective Lagrangian that restore renormalization group invariance.
We study de Wit-Hoppe-Nicolai supermembrane with emphasis on the winding in M-direction. We propose a SUSY algebra of the supermembrane in the Lorentz invariant form. We analyze the BPS conditions and argue that the area preserving diffeomorphism constraints associated with the harmonic vector fields play an essential role. We derive the first order partial differential equation that describes the BPS state with one quarter SUSY.
Currently available information on fast variability of the X-ray emission from accreting collapsed objects constitutes a complex phenomenology which is difficult to interpret. We review the current observational standpoint for black-hole binaries and survey models that have been proposed to interpret it. Despite the complex structure of the accretion flow, key observational diagnostics have been identified which can provide direct access to the dynamics of matter motions in the close vicinity of black holes and thus to the some of fundamental properties of curved spacetimes, where strong-field general relativistic effects can be observed.
We present a derivation of the exact sign-time distribution for a random walker in the presence of a boundary moving with constant velocity.
We report the discovery of 59 new ghostly absorbers from the Sloan Digital Sky Survey (SDSS) Data Release 14 (DR14). These absorbers, with $z_{\rm abs}$$\sim$$z_{\rm QSO}$, reveal no Ly$\alpha$ absorption, and they are mainly identified through the detection of strong metal absorption lines in the spectra. The number of previously known such systems is 30. The new systems are found with the aid of machine learning algorithms. The spectra of 41 (out of total of 89) absorbers also cover the Ly$\beta$ spectral region. By fitting the damping wings of the Ly$\beta$ absorption in the stacked spectrum of 21 (out of 41) absorbers with relatively stronger Ly$\beta$ absorption, we measured an HI column density of log$N$(HI)=21.50. This column density is 0.5dex higher than that of the previous work. We also found that the metal absorption lines in the stacked spectrum of the 21 ghostly absorbers with stronger Ly$\beta$ absorption have similar properties as those in the stacked spectrum of the remaining systems. These circumstantial evidence strongly suggest that the majority of our ghostly absorbers are indeed DLAs.
A sunflower with $k$ petals, or $k$-sunflower, is a family of $k$ sets every two of which have a common intersection. Known since 1960, the sunflower conjecture states that a family ${\mathcal F}$ of sets each of cardinality $m$ includes a $k$-sunflower if $|{\mathcal F}| \ge c_k^m$ for some $c_k \in {\mathbb R}_{>0}$ depending only on $k$. The case $k=3$ of the conjecture was especially emphasized by Erd\"os, for which Kostochka's bound $c m! \left( \frac{\log \log \log m}{\log \log m} \right)^m$ on $|{\mathcal F}|$ without a 3-sunflower had been the best-known since 1997 until the recent development to update it to $c \log m$. This paper proves with an entirely different combinatorial approach that ${\mathcal F}$ includes three mutually disjoint sets if it satisfies the $\Gamma \left( c m^{\frac{1}{2}+ \delta} \right)$-condition for any given $\delta \in (0, 1/2)$. Here $c$ is a constant depending only on $\delta$, and the $\Gamma$-condition refers to \[ | \left\{ U~:~ U \in {\mathcal F} \textrm{~and~} S \subset U \right\}| < \left( c m^{\frac{1}{2}+ \delta} \right)^{-|S|} |{\mathcal F}|, \] for every nonempty set $S$. This poses an alternative proof of the 3-sunflower bound $\left( c m^{\frac{1}{2}+ \delta} \right)^m$.
Fast radio bursts (FRBs) are quickly becoming a subject of intense interest in time-domain astronomy. The progenitors of FRBs remain unknown but a wide variety of models exist from cataclysmic to repeating scenarios. Advances in FRB detection using current and next-generation radio telescopes will enable the growth of the population in the next few years. Real-time discovery of FRBs is now possible with 6 sources detected in real-time within the past 2 years at the Parkes telescope. Here we discuss the developing strategies for maximising real-time science with FRBs including polarisation capture and multi-wavelength follow-up, with particular focus on real-time detections with the Parkes telescope as a test bed for fast radio burst science. We also discuss how our response to these events can pave the way for the next generation of FRB searches with wide-field interferometers.
We study the cluster environment for a sample of 21 radio loud AGN from the 3CR catalog at z>1, 12 radio galaxies and 9 quasars with HST images in the optical and IR. We use two different approaches to determine cluster candidates. We identify the early type galaxies (ETGs) in every field by modeling each of the sources within a 40" radius of the targets with a Sersic profile. Using a simple passive evolution model, we derive the expected location of the ETGs on the red sequence (RS) in the color-magnitude diagram for each of the fields of our sources. For seven targets, the model coincides with the position of the ETGs. A second approach involves a search for over densities. We compare the object densities of the sample as a whole and individually against control fields taken from the GOODS-S region of 3D-HST survey. With this method we determine the fields of 10 targets to be cluster candidates. Four cluster candidates are found by both methods. The two methods disagree in some cases, depending on the specific properties of each field. For the most distant radio galaxy in the 3CR catalog (3C257 at z = 2.47), we identify a population of bluer ETGs that lie on the expected location of the RS model for that redshift. This appears to be the general behavior of ETGs in our fields and it is possibly a signature of the evolution of such galaxies. Our results are consistent with half of the z > 1 radio galaxies being located in dense, rapidly evolving environments.
Using archival data from the Chandra X-ray telescope, we have measured the spatial extent of the hot interstellar gas in a sample of 49 nearby interacting galaxy pairs, mergers, and merger remnants. For systems with SFR > 1 M(sun)/yr, the volume and mass of hot gas are strongly and linearly correlated with the star formation rate (SFR). This supports the idea that stellar/supernovae feedback dominates the production of hot gas in these galaxies. We compared the mass of X-ray-emitting hot gas Mx(gas) with the molecular and atomic hydrogen interstellar gas masses in these galaxies (M(H2) and M(HI), respectively), using published carbon monoxide and 21 cm HI measurements. Systems with higher SFRs have larger Mx(gas)/(M(H2) + M(HI)) ratios on average, in agreement with recent numerical simulations of star formation and feedback in merging galaxies. The Mx(gas)/(M(H2) + M(HI)) ratio also increases with dust temperature on average. The ratio Mx(gas)/SFR is anti-correlated with the IRAS 60 micron to 100 micron flux ratio and with the Spitzer 3.6 micron to 24 micron. These trends may be due to variations in the spatial density of young stars, the stellar age, the ratio of young to old stars, the initial mass function, and/or the efficiency of stellar feedback. Galaxies with low SFR (<1 M(sun)/yr) and high K band luminosities may have an excess of hot gas relative to the relation for higher SFR galaxies, while galaxies with low K band luminosities (and therefore low stellar masses) may have a deficiency in hot gas, but our sample is not large enough for strong statistical significance.
We analyze the effective 3 dimensional theory previously constructed for the MSSM and multi-Higgs models to determine the regions of parameter space in which the electroweak phase transition is sufficiently strong for a $B+L$ asymmetry to survive in the low temperature phase. We find that the inclusion of all supersymmetric scalars and all 1-loop corrections has the effect of enhancing the strength of the phase transition. Without a light stop or extension of the MSSM the phase transition is sufficiently first order only if the lightest Higgs mass $M_{h}\lsi 70$ GeV and $tan\beta\lsi 1.75$.
After the short survey of the Klein Paradox in 3-dimensional relativistic equations, we present a detailed consideration of Dirac modified equation, which follows by one particle infinite overweighting in Salpeter Equation. It is shown, that the separation of angular variables and reduction to radial equation is possible by using standard methods in momentum space. The kernel of the obtained radial equation differs from that of spinless Salpeter equation in bounded regular factor. That is why the equation has solutions of confined type for infinitely increasing potential.