Miracle-dz/UniFAR-FTUs huggingface dataset:
Isomorph invariance and thermodynamics of repulsive dense bi-Yukawa one-component plasmas

In numerous realizations of complex plasmas, dust-dust interactions are characterized by two screening lengths and are thus better described by a combination of Yukawa potentials. The present work investigates the static correlations and the thermodynamics of repulsive dense bi-Yukawa fluids based on the fact that such strongly coupled systems exhibit isomorph invariance. The strong virial-potential energy correlations are demonstrated with the aid of molecular dynamics simulations, an accurate analytical expression for the isomorph family of curves is obtained, and an empirical expression for the fluid-solid phase-coexistence line is proposed. The isomorph-based empirically modified hypernetted-chain approach, grounded on the ansatz of isomorph invariant bridge functions, is then extended to such systems and the resulting structural properties show an excellent agreement with the results of computer simulations. A simple and accurate closed-form expression is obtained for the excess internal energy of dense bi-Yukawa fluids by capitalizing on the compact parameterization offered by the Rosenfeld-Tarazona decomposition in combination with the Rosenfeld scaling, which opens up the energy route to thermodynamics.In numerous realizations of complex plasmas, dust-dust interactions are characterized by two screening lengths and are thus better described by a combination of Yukawa potentials. The present work investigates the static correlations and the thermodynamics of repulsive dense bi-Yukawa fluids based on the fact that such strongly coupled systems exhibit isomorph invariance. The strong virial-potential energy correlations are demonstrated with the aid of molecular dynamics simulations, an accurate analytical expression for the isomorph family of curves is obtained, and an empirical expression for the fluid-solid phase-coexistence line is proposed. The isomorph-based empirically modified hypernetted-chain approach, grounded on the ansatz of isomorph invariant bridge functions, is then extended to such systems and the resulting structural properties show an excellent agreement with the results of computer simulations. A simple and accurate closed-form expression is obtained for the excess internal energy of de.
A sharp threshold for van der Waerden's theorem in random subsets

We establish sharpness for the threshold of van der Waerden's theorem in random subsets of $\mathbb{Z}/n\mathbb{Z}$. More precisely, for $k\geq 3$ and $Z\subseteq \mathbb{Z}/n\mathbb{Z}$ we say $Z$ has the van der Waerden property if any two-colouring of $Z$ yields a monochromatic arithmetic progression of length $k$. R\"odl and Ruci\'nski (1995) determined the threshold for this property for any k and we show that this threshold is sharp. The proof is based on Friedgut's criteria (1999) for sharp thresholds, and on the recently developed container method for independent sets in hypergraphs by Balogh, Morris and Samotij (2015) and by Saxton and Thomason (2015).
Calibrating emission lines as quasar bolometers

Historically, emission lines have been considered a valuable tool for estimating the bolometric thermal luminosity of the accretion flow in active galactic nucleus, Lbol. We study the reliability of this method by comparing line strengths to the optical/ultraviolet continuum luminosity of Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) radio-quiet quasars with 0.4 < z < 0.8. We find formulae for Lbol as a function of single line strengths for the broad components of Hβ and Mg ii, as well as the narrow lines of [O iii] and [O ii]. We determine the standard errors of the formulae that are fitted to the data. Our new estimators are shown to be more accurate than archival line strength estimations in the literature. It is demonstrated that broad lines are superior estimators of the continuum luminosity (and Lbol) with Hβ being the most reliable. The fidelity of each of the estimators is determined in the context of the SDSS DR7 radio-loud quasars as an illustrative application of our results. In general, individual researchers can use our results as a tool to decide if a particular line strength provides an adequate estimate of Lbol for their purposes. Finally, it is shown that considering all four line strengths, simultaneously, can yield information on both Lbol and the radio jet power.
Giant gain enhancement in surface‐confined resonant Stimulated Brillouin Scattering

The notion that Stimulated Brillouin Scattering (SBS) is primarily defined by bulk material properties has been overturned by recent work on nanoscale waveguides. It is now understood that boundary forces of radiation pressure and electrostriction appearing in such highly confined waveguides can make a significant contribution to the Brillouin gain. Here, this concept is extended to show that gain enhancement does not require nanoscale or subwavelength features, but generally appears where optical and acoustic fields are simultaneously confined near a free surface or material interface. This situation routinely occurs in whispering gallery resonators (WGRs), making gain enhancements much more accessible than previously thought. To illustrate this concept, the first full‐vectorial analytic model for SBS in WGRs is developed, including optical boundary forces, and the SBS gain in common silica WGR geometries is computationally evaluated. These results predict that gains 104 times greater than the predictions of scalar theory may appear in WGRs even in the 100 μm size range. Further, trapezoidal cross‐section microdisks can exhibit very large SBS gains approaching 102 m−1W−1. With resonant amplification included, extreme gains on the order of 1012 m−1W−1 may be realized, which is 108 times greater than the highest predicted gains in linear waveguide systems.
Attenuation‐tunable balanced bandpass filter based on graphene nanoplates

In this letter, a unique type of balanced bandpass filter (BPF) with high selectivity and tunable attenuation is proposed through the comprehensive design of a microstrip balanced BPF and graphene nanoplates. In order to achieve the passband response in differential‐mode (DM) excitation and produce a wide and deep stopband in common‐mode (CM) excitation, the balanced couple of lines are used in balanced BPF. The graphene nanoplates are loaded on the open ends of λ /4 stepped‐impedance resonators to dissipate the electromagnetic field. By raising the bias voltage applied to the graphene nanoplates, the values of the graphene's surface impedance can be adjusted from high to low. The insertion loss of the balanced BPF can be indirectly tuned while maintaining the return loss at a comparatively low level. A prototype of the proposed gain tunable balanced BPF is fabricated and measured. The measured results show that a tuning range of insertion loss from 1.75 to 10.7 dB can be obtained for the DM circuit over the operating bandwidth centered at 1.84 GHz, without interrupting the signal rejection of the CM circuit.
Trauma-Informed Design of Supported Housing: A Scoping Review through the Lens of Neuroscience

There is growing recognition of the importance of the design of the built environment in supporting mental health. In this context, trauma-informed design has emerged as a new field of practice targeting the design of the built environment to support wellbeing and ameliorate the physical, psychological and emotional impacts of trauma and related pathologies such as Post Traumatic Stress Disorder (PTSD). With high levels of prevalence of PTSD among people escaping homelessness and domestic violence, a priority area is the identification and application of evidence-based design solutions for trauma-informed supported housing. This study sought to examine the scope of existing evidence on the relationship between trauma, housing and design and the correlation of this evidence with trauma-informed design principles, and to identify gaps and opportunities for future research. In response to the commonly articulated limitations of the evidence-base in built environment design research, we combined a scoping review of literature on trauma, housing and design with insights from neuroscience to focus and extend understanding of the opportunities of trauma-informed design. We found that while limited in scope, there is strong alignment between existing evidence and the principles of trauma-informed design. We also identify three areas of future research related to the key domains of safety and security; control; and enriched environments.
JET ROTATION DRIVEN BY MAGNETOHYDRODYNAMIC SHOCKS IN HELICAL MAGNETIC FIELDS

In this paper, we present a detailed numerical investigation of the hypothesis that a rotation of astrophysical jets can be caused by magnetohydrodynamic (MHD) shocks in a helical magnetic field. Shock compression of the helical magnetic field results in a toroidal Lorentz force component that will accelerate the jet material in the toroidal direction. This process transforms magnetic angular momentum (magnetic stress) carried along the jet into kinetic angular momentum (rotation). The mechanism proposed here only works in a helical magnetic field configuration. We demonstrate the feasibility of this mechanism by axisymmetric MHD simulations in 1.5 and 2.5 dimensions using the PLUTO code. In our setup, the jet is injected into the ambient gas with zero kinetic angular momentum (no rotation). We apply different dynamical parameters for jet propagation such as the jet internal Alfvén Mach number and fast magnetosonic Mach number, the density contrast of the jet to the ambient medium, and the external sonic Mach number of the jet. The mechanism we suggest should work for a variety of jet applications, e.g., protostellar or extragalactic jets, and internal jet shocks (jet knots) or external shocks between the jet and the ambient gas (entrainment). For typical parameter values for protostellar jets, the numerically derived rotation feature looks consistent with the observations, i.e., rotational velocities of 0.1%–1% of the jet bulk velocity.
A giant elliptical galaxy with a lightweight initial mass function

We present new observations of the closest known strong-lensing galaxy, the σ ≈ 330 km s− 1 giant elliptical ESO325−G004, made with the ESO Very Large Telescope. The low redshift of the lens (zl = 0.035) results in arcs being formed at a small fraction of the effective radius (REin = 2.85 arcsec ≈ Reff/4). At such small radii, stars dominate the lensing mass, so that lensing provides a direct probe of the stellar mass-to-light ratio, with only small corrections needed for dark matter. However, the redshift of the galaxy lensed by ESO325−G004 was unknown until now, so the lensing mass was not securely determined. Using X-SHOOTER, we have detected multiple spectral lines, from two bright parts of the arc system, and measured a source redshift of zs = 2.141. Combined with lens modelling constraints, this yields a total mass inside the Einstein radius of 1.50 ± 0.06 × 1011 M⊙. We estimate the range of possible contribution of dark matter to the lensing mass, using halo profile statistics from cosmological N-body simulations. Subtracting this component yields a stellar mass-to-light ratio for the lens of M*/LF814W =3.14+0.24−0.42(M/L)⊙,F814W. Using VIMOS, we have also obtained very high signal-to-noise spectroscopy for the lens galaxy. Fitting models to this spectrum confirms that ESO325−G004 has a very old stellar population. For a Milky-Way-like (Kroupa) initial mass function (IMF), the stellar population fit yields a predicted stellar mass-to-light ratio of ϒMW = 3.01 ± 0.25 (M/L)⊙, F814W. Hence, the mass attributable to stars with a Kroupa IMF is consistent with the lensing estimate. By contrast, a Salpeter (or heavier) IMF is disfavoured at the 99.8 per cent confidence level. A ‘heavyweight’ IMF, with a mass twice as large as the Kroupa case, is firmly excluded for this galaxy. Such an IMF has been proposed for more distant elliptical lenses, and also to explain strong dwarf-star-sensitive spectral features, in particular the Na I 8200 A doublet. A FORS2 far-red spectrum shows that this feature is as strong in ESO325−G004 as it is in other high-σ ellipticals, suggesting tension between dwarf-star indicators and lensing-mass constraints for this galaxy.
VERIFICATION OF THE KEPLER INPUT CATALOG FROM ASTEROSEISMOLOGY OF SOLAR-TYPE STARS

We calculate precise stellar radii and surface gravities from the asteroseismic analysis of over 500 solar-type pulsating stars observed by the Kepler space telescope. These physical stellar properties are compared with those given in the Kepler Input Catalog (KIC), determined from ground-based multi-color photometry. For the stars in our sample, we find general agreement but we detect an average overestimation bias of 0.23 dex in the KIC determination of log (g) for stars with log (g)KIC > 4.0 dex, and a resultant underestimation bias of up to 50% in the KIC radii estimates for stars with RKIC < 2 R☉. Part of the difference may arise from selection bias in the asteroseismic sample; nevertheless, this result implies there may be fewer stars characterized in the KIC with R ∼ 1 R☉ than is suggested by the physical properties in the KIC. Furthermore, if the radius estimates are taken from the KIC for these affected stars and then used to calculate the size of transiting planets, a similar underestimation bias may be applied to the planetary radii.
A Chandra view of the z=1.62 galaxy cluster IRC-0218A

Context: Very few z > 1.5 clusters of galaxies are known. It is important to study the properties of galaxies in these clusters and the ICM and, further, to cross-check the reliability of the various mass estimates. This will help to clarify the process of structure formation and how distant clusters may be used to constrain cosmology. AIMS: We present a 84 ks Chandra observation of IRC-0218A, a cluster of galaxies inferred by the presence of a galaxy overdensity in the infrared at a redshift of 1.62 and associated with some XMM emission Methods: Spatial analysis of the Chandra X-ray photon distribution. Results: The Chandra observation of IRC-0218A appears to be entirely dominated by a point-source located at the centroid of the MIR galaxy density. In addition, we detect weak extended emission (2.3 sigma) out to a radius of 25" with a flux of ~ 3 10E-15 erg/s/cm2 in the [0.3-2]keV band. Assuming that clusters evolve similarly, we infer a virial mass of M200 =7.7+/-3.8 10E13Mo. This is marginally compatible with our current estimate of the cluster dynamical mass (based on 10 redshifts), although there is no evidence that the galaxy peculiar velocities correspond to the motions of a virialized structure. The stellar mass enclosed in the inferred X-ray virial radius is estimated to 1-2 10E12 Mo. We provide a detailed account of 28 X-ray point-sources detected in the field.
THE EFFECTS OF REFRACTION ON TRANSIT TRANSMISSION SPECTROSCOPY: APPLICATION TO EARTH-LIKE EXOPLANETS

We quantify the effects of refraction in transit transmission spectroscopy on spectral absorption features and on temporal variations that could be used to obtain altitude-dependent spectra for planets orbiting stars of different stellar types. We validate our model against altitude-dependent transmission spectra of the Earth from ATMOS and against lunar eclipse spectra from Pallé et al. We perform detectability studies to show the potential effects of refraction on hypothetical observations of Earth analogs with the James Webb Space Telescope NIRSPEC. Due to refraction, there will be a maximum tangent pressure level that can be probed during transit for each given planet–star system. We show that because of refraction, for an Earth-analog planet orbiting in the habitable zone of a Sun-like star only the top 0.3 bars of the atmosphere can be probed, leading to a decrease in the signal-to-noise ratio (S/N) of absorption features by 60%, while for an Earth-analog planet orbiting in the habitable zone of an M5V star it is possible to probe almost the entire atmosphere with minimal decreases in S/N. We also show that refraction can result in temporal variations in the transit transmission spectrum which may provide a way to obtain altitude-dependent spectra of exoplanet atmospheres. Additionally, the variations prior to ingress and subsequent to egress provide a way to probe pressures greater than the maximum tangent pressure that can be probed during transit. Therefore, probing the maximum range of atmospheric altitudes, and in particular the near-surface environment of an Earth-analog exoplanet, will require looking at out-of-transit refracted light in addition to the in-transit spectrum.
A comprehensive study of RXTE and INTEGRAL observations of the X-ray pulsar 4U 1907+09

We analyse observations of the accretion-powered pulsar 4U 1907+09 from the International Gamma-Ray Astrophysics Laboratory (INTEGRAL; between 2005 October and 2007 November) and from the Rossi X-ray Timing Explorer (RXTE; between 2007 June and 2011 March). Using observations from the Imager on-board the INTEGRAL satellite (IBIS), the INTEGRAL Soft Gamma-Ray Imager (ISGRI) and the RXTE Proportional Counter Array (PCA), we update the pulse period history of the source. We construct power spectrum density of pulse frequencies, and we find that fluctuations in the pulse frequency derivatives are consistent with the random walk model with a noise strength of 1.27 × 10−21 Hz s−2. From the X-ray spectral analysis of RXTE/PCA observations, we find that the hydrogen column density is variable over the binary orbit, and that it tends to increase just after the periastron passage. We also show that the X-ray spectrum becomes hardened with decreasing X-ray flux. We discuss the pulse-to-pulse variability of the source near dipping ingress and egress. We find that the source is more likely to undergo dipping states after apastron until periastron when the accretion from clumpy wind might dominate. Thus, occasional transitions to a temporary propeller state might occur.
Closed hierarchy of correlations in Markovian open quantum systems

We study the Lindblad master equation in the space of operators and provide simple criteria for closeness of the hierarchy of equations for correlations. We separately consider the time evolution of closed and open systems and show that open systems satisfying the closeness conditions are not necessary of Gaussian type. In addition, we show that dissipation can induce the closeness of the hierarchy of correlations in interacting quantum systems. As an example we study an interacting optomechanical model, the Fermi-Hubbard model, and the Rabi model, all coupled to a fine-tuned Markovian environment and obtain exact analytic expressions for the time evolution of two-point correlations. ar X iv :1 31 0. 22 78 v2 [ qu an tph ] 1 8 O ct 2 01 3 Closed hierarchy of correlations in Markovian open quantum systems 2
Employability Prediction of Information Technology Graduates using Machine Learning Algorithms

—The ability to predict graduates’ employability to match labor market demands is crucial for any educational institution aiming to enhance students' performance and learning process as graduates’ employability is the metric of success for any higher education institution (HEI). Especially information technology (IT) graduates, due to the evolving demand for IT professionals increased in the current era. Job mismatch and unemployment remain major challenges and issues for educational institutions due to the various factors that influence graduates' employability to match labor market needs. Therefore, this paper aims to introduce a predictive model using machine learning (ML) algorithms to predict information technology graduates’ employability to match the labor market demands. Five machine learning classification algorithms were applied named Decision tree (DT), Gaussian Naïve Bayes (Gaussian NB), Logistic Regression (LR), Random Forest (RF), and Support Vector Machine (SVM). The dataset used in this study is collected based on a survey given to IT graduates and employers. The performance of the study is evaluated in terms of accuracy, precision, recall, and f1 score. The results showed that DT achieved the highest accuracy, and the second highest accuracy was achieved by LR and SVM.
Interaction of electron vortices and optical vortices with matter and processes of orbital angular momentum exchange

The quantum processes involved in the interaction of matter with, separately, an electron vortex (EV) and an optical vortex (OV) are described, with matter modeled in terms of a neutral two-particle atomic system, allowing for both the internal (electronic-type) motion and the gross (center-of-mass-type) motion of matter to be taken into account. The coupling of the atomic system to the EV is dominated by Coulomb forces, while that of the OV is taken in the p·A canonical form which couples A, the transverse vector potential of the optical vortex, to the linear momenta of the two-particle system. An analysis of the dipole active transition matrix element is carried out in each case. The electron vortex is found to be capable of exchanging its orbital angular momentum (OAM) with both the electronic and the center-of-mass motions of the atomic system in an electric dipole transition. In contrast, for electric dipole transitions the optical vortex is found to be capable of exchanging OAM only with the center of mass. The predictions are discussed with reference to recent experiments on electron-energy-loss spectroscopy using EVs traversing magnetized iron thin-film samples and those involving OVs interacting with chiral molecules.
Higher secant varieties of $\mathbb P^n \times\mathbb P^ 1$ embedded in bi-degree $(a,b)$

In this paper we compute the dimension of all the higher secant varieties to the Segre-Veronese embedding of $\mathbb{P}^n\times \mathbb{P}^1$ via the section of the sheaf $\mathcal{O}(a,b)$ for any $n,a,b\in \mathbb{Z}^+$. We relate this result to the Grassmann Defectivity of Veronese varieties and we classify all the Grassmann $(1,s-1)$-defective Veronese varieties.
Broad Learning System-Based Detector for OFDM With Index Modulation

This letter presents a broad learning system (BLS) based orthogonal frequency division multiplexing with index modulation (OFDM-IM) detector called BLS-IM, which achieves bit-error-rate performance improvement with less training time. In BLS-IM, in order to help the network detect the index of the active subcarrier, the received data needs to be preprocessed into polar coordinates first. The processed data is then fed into the BLS network. In particular, the BLS is built in the form of a flat network where the initial signal bits are transferred among the feature nodes. At the same time, the structure is extended in a broad sense in terms of enhanced nodes. The proposed BLS-IM detector has an advantage in training time because it avoids the time-consuming training process caused by a large number of connection parameters in the layers. Simulation results demonstrate that BLS-IM is capable of achieving better detection performance with less training time than the existing algorithms.