Miracle-dz/UniFAR-FTUs huggingface dataset:
Symmetry-broken states in a system of interacting bosons on a two-leg ladder with a uniform Abelian gauge field

We study the quantum phases of bosons with repulsive contact interactions on a two-leg ladder in the presence of a uniform Abelian gauge field. The model realizes many interesting states, including Meissner phases, vortex fluids, vortex lattices, charge density waves, and the biased-ladder phase. Our work focuses on the subset of these states that breaks a discrete symmetry. We use density matrix renormalization group simulations to demonstrate the existence of three vortex-lattice states at different vortex densities and we characterize the phase transitions from these phases into neighboring states. Furthermore, we provide an intuitive explanation of the chiral-current reversal effect that is tied to some of these vortex lattices. We also study a charge-density-wave state that exists at 1/4 particle filling at large interaction strengths and flux values close to half a flux quantum. By changing the system parameters, this state can transition into a completely gapped vortex-lattice Mott-insulating state. We elucidate the stability of these phases against nearest-neighbor interactions on the rungs of the ladder relevant for experimental realizations with a synthetic lattice dimension. A charge-density-wave state at 1/3 particle filling can be stabilized for flux values close to half a flux quantum and for very strong on-site interactions in the presence of strong repulsion on the rungs. Finally, we analytically describe the emergence of these phases in the low-density regime, and, in particular, we obtain the boundaries of the biased-ladder phase, i.e., the phase that features a density imbalance between the legs. We make contact with recent quantum-gas experiments that realized related models and discuss signatures of these quantum states in experimentally accessible observables.
Making Sense of Factor Analysis: The Use of Factor Analysis for Instrument Development in Health Care Research

1. An Overview of Factor Analysis Characteristics of Factor Analysis Exploratory Vs. Confirmatory Factor Analysis Assumptions of Exploratory Factor Analysis Historical Developments of Factor Analysis Uses of Factor Analysis in Health Care Research Decision-Making Process in Exploratory Factor Analysis 2. Designing and Testing the Instrument Types of Measurement and Frameworks The Use of Latent Variables in Instrument Development Identifying Empirical Indicators of Latent Variables Using Qualitative Research Methods to Identify Empirical Indicators Additional Qualitative Approaches to Identifying Empirical Indicators Development of the Instrument Scoring the Instrument Pilot Testing the Instrument Determining the Number of Subjects 3. Assessing the Characteristics of Matrices Characteristics and Types of Matrices Tests of Matrices Review of the Process 4. Extracting the Initial Factors Evaluating the Correlation Matrix Sources of Variance in Factor Analysis Models Determining the Factor Extraction Method Selecting the Number of Factors to Retain Comparing the Two-Factor Solution Using PCA and PAF 5. Rotating the Factors Achieving a Simple Structure Types of Rotations Mapping Factors in Geometric Space Orthogonal Rotations Oblique Rotations Comparing the Orthogonal and Oblique Solutions Advantages and Disadvantages of the Oblique Solution Choosing Between Orthogonal and Oblique Rotations Summary of the Process of Rotations 6. Evaluating and Refining the Factors Evaluating and Refining the Factors Assessing the Reliability of an Instrument Evaluating the Internal Consistency of an Instrument Estimating the Effects on Reliability of Increasing or Decreasing Items Cronbach's Coefficient Alpha Assessing Reliability Using Cronbach's Alpha: A Computer Example Two Additional Reliability Estimates: Temporal Stability and Equivalence 7. Interpreting Factors and Generating Factor Scores Interpreting the Factors Naming the Factors Interpreting and Naming the Four Factors on the CGTS Scale Determining Composite Factor Scores 8. Reporting and Replicating the Results When to Report the Results What to Include in the Report An Exemplar of a Published Report Replicating the Factors in Other Studies Conclusions Appendix A: Concerns About Genetic Testing Scale Appendix B: SAS Commands and Generate Output Appendix C: Output for 20-item CGTS Scale Appendix D: Tables for the Chi-Square and Normal Distributions Appendix E: Unraveling the Mystery of Principal Component Extraction References Index About the Authors
Dark matter annihilation and decay from non-spherical dark halos in galactic dwarf satellites

The dwarf spheroidal galaxies (dSphs) in the Milky Way are the primary targets in the indirect searches for particle dark matter. To set robust constraints on candidate of dark matter particles, understanding the dark halo structure of these systems is of substantial importance. In this paper, we rst evaluate the astrophysical factors for dark matter annihilation and decay for 24 dSphs, with taking into account a non-spherical dark halo, using generalized axisymmetric mass models based on axisymmetric Jeans equations. First, from a tting analysis of the most recent kinematic data available, our axisymmetric mass models are a much better
DWARF GALAXY DARK MATTER DENSITY PROFILES INFERRED FROM STELLAR AND GAS KINEMATICS

We present new constraints on the density profiles of dark matter (DM) halos in seven nearby dwarf galaxies from measurements of their integrated stellar light and gas kinematics. The gas kinematics of low-mass galaxies frequently suggest that they contain constant density DM cores, while N-body simulations instead predict a cuspy profile. We present a data set of high-resolution integral-field spectroscopy on seven galaxies and measure the stellar and gas kinematics simultaneously. Using Jeans modeling on our full sample, we examine whether gas kinematics in general produce shallower density profiles than are derived from the stars. Although two of the seven galaxies show some localized differences in their rotation curves between the two tracers, estimates of the central logarithmic slope of the DM density profile, γ, are generally robust. The mean and standard deviation of the logarithmic slope for the population are γ = 0.67 ± 0.10 when measured in the stars and γ = 0.58 ± 0.24 when measured in the gas. We also find that the halos are not under-concentrated at the radii of half their maximum velocities. Finally, we search for correlations of the DM density profile with stellar velocity anisotropy and other baryonic properties. Two popular mechanisms to explain cored DM halos are an exotic DM component or feedback models that strongly couple the energy of supernovae into repeatedly driving out gas and dynamically heating the DM halos. While such models do not yet have falsifiable predictions that we can measure, we investigate correlations that may eventually be used to test models. We do not find a secondary parameter that strongly correlates with the central DM density slope, but we do find some weak correlations. The central DM density slope weakly correlates with the abundance of α elements in the stellar population, anti-correlates with H i fraction, and anti-correlates with vertical orbital anisotropy. We expect, if anything, the opposite of these three trends for feedback models. Determining the importance of these correlations will require further model developments and larger observational samples.
Metacyclic $p$-groups and Chern classes

C. B. Thomas [9] shows that the even-dimensional subring Heven(G, Z) ofthe integral cohomology ring H*(G, Z) of some split metacyclic p-group G is generated by Chern classes, and hence this group satisfies Atiyah’s conjecture [1]. This result is generalized here, to a non-split metacyclic p-group by using the computational method of G. Lewis [7] together with the property of free action of G on product of two spheres. HeVe"(G, Z) is expressed in terms of Chern classes of certain representations of G. The author is greatly indebted to Dr. C. B. Thomas, who, as his research supervisor, gave invaluable assistance in preparation of this work at University College London.
ON THE NATURE OF THE mHz X-RAY QUASI-PERIODIC OSCILLATIONS FROM ULTRALUMINOUS X-RAY SOURCE M82 X−1: SEARCH FOR TIMING–SPECTRAL CORRELATIONS

Using all the archival XMM-Newton X-ray (3–10 keV) observations of the ultraluminous X-ray source (ULX) M82 X−1, we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its hardness ratio (5–10 keV/3–5 keV), an indicator of the energy spectral power-law index. When stellar-mass black holes (StMBHs) exhibit type-C low-frequency QPOs (∼0.2–15 Hz), the centroid frequency of the QPO is known to correlate with the energy spectral index. The detection of such a correlation would strengthen the identification of M82 X−1's mHz QPOs as type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of type-C QPOs in StMBHs of known mass. We resolved the count rates and the hardness ratios of M82 X−1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling. We detected QPOs in the frequency range of 36–210 mHz during which M82 X−1's hardness ratio varied from 0.42 to 0.47. Our primary results are (1) that we do not detect any correlation between the mHz QPO frequency and the hardness ratio (a substitute for the energy spectral power-law index) and (2) similar to some accreting X-ray binaries, we find that M82 X−1's mHz QPO frequency increases with its X-ray count rate (Pearson's correlation coefficient = +0.97). The apparent lack of a correlation between the QPO centroid frequency and the hardness ratio poses a challenge to the earlier claims that the mHz QPOs of M82 X−1 are the analogs of the type-C low-frequency QPOs of StMBHs. On the other hand, it is possible that the observed relation between the hardness ratio and the QPO frequency represents the saturated portion of the correlation seen in type-C QPOs of StMBHs—in which case M82 X−1's mHz QPOs can still be analogous to type-C QPOs.
Greedy Type Bases in Banach Spaces

Let (X, · ) be a (real) Banach space. We refer to [38] or [28] as some introduction to the general theory of Banach spaces. Note that, as usual in the case, all the results we discuss here remain valid for complex scalars with possibly different constants. Let I be a countable set with possibly some ordering we refer to whenever considering convergence with respect to elements of I (wich will be denoted by limi→∞). Definition 1 We say that countable system of vectors is biorthogonal if for i, j ∈ I we have
The collimation of magnetic jets by disc winds

The collimation of a Poynting-flux dominated jet by a wind emanating from the surface of an accretion flow is computed using a semi-analytic model. The injection of the disk wind is treated as a boundary condition in the equatorial plane, and its evolution is followed by invoking a prescribed geometry of streamlines. Solutions are obtained for a wide range of disk wind parameters. It is found that jet collimation generally occurs when the total wind power exceeds about ten percents of the jet power. For moderate wind powers we find gradual collimation. For strong winds we find rapid collimation followed by focusing of the jet, after which it remains narrow over many Alfven crossing times before becoming conical. We estimate that in the later case the jet’s magnetic field may be dissipated by the current-driven kink instability over a distance of a few hundreds gravitational radii. We apply the model to M87 and show that the observed parabolic shape of the radio jet within the Bondi radius can be reproduced provided that the wind injection zone extends to several hundreds gravitational radii, and that its total power is about one third of the jet power. The radio spectrum can be produced by synchrotron radiation of relativistically hot, thermal electrons in the sheath flow surrounding the inner jet.
Investigating Agricultural Production Relations Across Bangladesh, India and Pakistan Using Vector Error Correction and Markov-Switching Models

This paper has investigated the short- and long-term relationships as well as regime switching behaviour between the per-capita agricultural production of Bangladesh, India and Pakistan using vector error correction model (VECM) and Markov-switching VECM model (MS-VECM). These countries were selected due to their high agricultural economic importance to the South Asian region. The study has used FAO’s statistical dataset and the study period was 1961-2010. The residual diagnostics have validated the models since there is no deficiency in normality, autocorrelation or heteroskedasticity. The empirical results have confirmed the existence of two long-term cointegrating vectors between the variables and have demonstrated that an unexpected shock to the respective log per-capita agricultural production of India and Pakistan cause transitory impacts. On the other hand, an unexpected shock to the log per-capita agricultural production of Bangladesh causes a permanent disequilibrium in all variables. Finally, MS-VECM model has shown two volatility regimes (i.e. low and high volatility). The Markov-switching impulse responses have indicated that, one, agricultural production adjustments in the first regime are smoother than those in the second regime, and two, these adjustments are faster in the case of a shock to the agricultural production of Pakistan than to the agricultural production of either Bangladesh or India.
THE TRUNCATED DISK FROM SUZAKU DATA OF GX 339−4 IN THE EXTREME VERY HIGH STATE

We report on the geometry of accretion disk and high-energy coronae in the strong Comptonization state (the very high/steep power law/hard intermediate state) based on a Suzaku observation of the famous Galactic black hole GX 339−4. These data were taken just before the peak of the 2006–2007 outburst, and the average X-ray luminosity in the 0.7–200 keV band is estimated to be 2.9 × 1038 erg s−1 for a distance of 8 kpc. We fit the spectrum with both simple (independent disk and corona) and sophisticated (energetically coupled disk and corona) models; all fits imply that the underlying optically thick disk is truncated significantly before the innermost stable circular orbit around the black hole. We show this directly by a comparison with similar broadband data from a disk-dominated spectrum at almost the same luminosity observed by XMM-Newton and RXTE 3 days after the Suzaku observation. During the Suzaku observation, the quasi-periodic oscillation (QPO) frequency changes from 4.3 Hz to 5.5 Hz, while the spectrum softens. The energetically coupled model gives a corresponding 5% ± 8% decrease in the derived inner radius of the disk. While this is not significant, it is consistent with the predicted change in QPO frequency from the Lense–Thirring precession of the hot flow interior to the disk and/or a deformation mode of this flow, as a higher QPO frequency implies a smaller size scale for the corona. This is consistent with the truncated disk extending further inward toward the black hole.
Photoconductive detectors based on partially ordered AlxGa1−xN alloys grown by molecular beam epitaxy

Photoconductive detectors based on partially ordered AlxGa1−xN alloys with AlN mole fractions up to 45% were fabricated and evaluated. The degree of ordering in these alloys was found to increase with the AlN mole fraction and it has a maximum value at about 50%. The resistivity of the AlxGa1−xN films was found to increase from 10 to 108 Ω cm by increasing the Al content in the films. Correspondingly, the mobility-lifetime (μτ) product, which was determined by measuring the photoconductive gain, was found to decrease from 10−2 to 10−5 cm2/V. These high values of the μτ product at the high AlN mole fraction are attributed to spatial separation and indirect recombination of the photogenerated electron hole pairs, due to band-gap misalignment of the ordered and disordered domains in these films.
ON PHYSICAL SCALES OF DARK MATTER HALOS

It is common practice to describe formal size and mass scales of dark matter halos as spherical overdensities with respect to an evolving density threshold. Here, we critically investigate the evolutionary effects of several such commonly used definitions and compare them to the halo evolution within fixed physical scales as well as to the evolution of other intrinsic physical properties of dark matter halos. It is shown that, in general, the traditional way of characterizing sizes and masses of halos dramatically overpredicts the degree of evolution in the last 10 Gyr, especially for low-mass halos. This pseudo-evolution leads to the illusion of growth even though there are no major changes within fixed physical scales. Such formal size definitions also serve as proxies for the virialized region of a halo in the literature. In general, those spherical overdensity scales do not coincide with the virialized region. A physically more precise nomenclature would be to simply characterize them by their very definition instead of calling such formal size and mass definitions “virial. ” In general, we find a discrepancy between the evolution of the underlying physical structure of dark matter halos seen in cosmological structure formation simulations and pseudo-evolving formal virial quantities. We question the importance of the role of formal virial quantities currently ubiquitously used in descriptions, models, and relations that involve properties of dark matter structures. Concepts and relations based on pseudo-evolving formal virial quantities do not properly reflect the actual evolution of dark matter halos and lead to an inaccurate picture of the physical evolution of our universe.
X-RAY CAVITIES, FILAMENTS, AND COLD FRONTS IN THE CORE OF THE GALAXY GROUP NGC 5044

We present a two-dimensional analysis of the bright nearby galaxy group NGC 5044 using the currently available Chandra and XMM data. In the inner 10 kpc, a pair of cavities are evident together with a set of bright X-ray filaments. If the cavities are interpreted as gas displaced by relativistic plasma inflated by an active galactic nucleus, even in the absence of extended 1.4 GHz emission, this would be consistent with a recent outburst as also indicated by the extent of dust and Hα emission. The soft X-ray filaments coincident with Hα and dust emission are cooler than those which do not correlate with optical and infrared emission. We suggest that dust-aided cooling contributes to form warm (T ∼ 104 K) gas, emitting Hα radiation. At 31 kpc and 67 kpc, a pair of cold fronts are present, indicative of sloshing due to a dynamical perturbation caused by accretion of a less-massive group, also suggested by the peculiar velocity of the brightest galaxy NGC 5044 with respect to the mean group velocity.
The long and the short of it: modelling double neutron star and collapsar Galactic dynamics

Understanding the nature of galactic populations of double compact binaries (where both stars are a neutron star or black hole) has been a topic of interest for many years, particularly the coalescence rate of these binaries. The only observed systems thus far are double neutron star systems containing one or more radio pulsars. However, theorists have postulated that short-duration gamma-ray bursts may be evidence of coalescing double neutron star or neutron star-black hole binaries, while long-duration gamma-ray bursts are possibly formed by tidally enhanced rapidly rotating massive stars that collapse to form black holes (collapsars). The work presented here examines populations of double compact binary systems and tidally enhanced collapsars. We make use of BINPOP and BINKIN, two components of a recently developed population synthesis package. Results focus on correlations of both binary and spatial evolutionary population characteristics. Pulsar and long-duration gamma-ray burst observations are used in concert with our models to draw the conclusions that (i) double neutron star binaries can merge rapidly on time-scales of a few million years (much less than that found for the observed double neutron star population), (ii) common-envelope evolution within these models is a very important phase in double neutron star formation and (iii) observations of long gamma-ray burst projected distances are more centrally concentrated than our simulated coalescing double neutron star and collapsar Galactic populations. Better agreement is found with dwarf galaxy models although the outcome is strongly linked to the assumed birth radial distribution. The birth rate of the double neutron star population in our models ranges from 4 to 160 Myr ―1 and the merger rate ranges from 3 to 150 Myr ―1 . The upper and lower limits of the rates result from including electron-capture supernova kicks to neutron stars and decreasing the common-envelope efficiency, respectively. Our double black hole merger rates suggest that black holes should receive an asymmetric kick at birth.
Stock Index Spot–Futures Arbitrage Prediction Using Machine Learning Models

With the development of quantitative finance, machine learning methods used in the financial fields have been given significant attention among researchers, investors, and traders. However, in the field of stock index spot–futures arbitrage, relevant work is still rare. Furthermore, existing work is mostly retrospective, rather than anticipatory of arbitrage opportunities. To close the gap, this study uses machine learning approaches based on historical high-frequency data to forecast spot–futures arbitrage opportunities for the China Security Index (CSI) 300. Firstly, the possibility of spot–futures arbitrage opportunities is identified through econometric models. Then, Exchange-Traded-Fund (ETF)-based portfolios are built to fit the movements of CSI 300 with the least tracking errors. A strategy consisting of non-arbitrage intervals and unwinding timing indicators is derived and proven profitable in a back-test. In forecasting, four machine learning methods are adopted to predict the indicator we acquired, namely Least Absolute Shrinkage and Selection Operator (LASSO), Extreme Gradient Boosting (XGBoost), Back Propagation Neural Network (BPNN), and Long Short-Term Memory neural network (LSTM). The performance of each algorithm is compared from two perspectives. One is an error perspective based on the Root-Mean-Squared Error (RMSE), Mean Absolute Percentage Error (MAPE), and goodness of fit (R2). Another is a return perspective based on the trade yield and the number of arbitrage opportunities captured. Finally, a performance heterogeneity analysis is conducted based on the separation of bull and bear markets. The results show that LSTM outperforms all other algorithms over the entire time period, with an RMSE of 0.00813, MAPE of 0.70 percent, R2 of 92.09 percent, and an arbitrage return of 58.18 percent. Meanwhile, in certain market conditions, namely both the bull market and bear market separately with a shorter period, LASSO can outperform.
Black hole entropy: Quantum versus thermal fluctuations

The relation between logarithmic corrections to the area law for black hole entropy, due to thermal fluctuations around an equilibrium canonical ensemble, and those originating from quantum spacetime fluctuations within a microcanonical framework, is explored for three and four dimensional asymptotically anti-de Sitter black holes. For the BTZ black hole, the two logarithmic corrections are seen to precisely cancel each other, while for four dimensional adS-Schwarzschild black holes a partial cancellation is obtained. We discuss the possibility of extending the analysis to asymptotically flat black holes.