Miracle-dz/UniFAR-FTUs huggingface dataset:
Cosmological axion and a quark nugget dark matter model

We study a dark matter (DM) model offering a very natural explanation of two (naively unrelated) problems in cosmology: the observed relation $\Omega_{\rm DM}\sim\Omega_{\rm visible}$ and the observed asymmetry between matter and antimatter in the Universe, known as the "baryogenesis" problem. In this framework, both types of matter (dark and visible) have the same QCD origin, form at the same QCD epoch, and both proportional to one and the same dimensional parameter of the system, $\Lambda_{\rm QCD}$, which explains how these two, naively distinct, problems could be intimately related, and could be solved simultaneously within the same framework. More specifically, the DM in this model is composed by two different ingredients: the (well- studied) DM axions and (less-studied) the quark nuggets made of matter or antimatter. The focus of the present work is the quantitative analysis of the relation between these two distinct components contributing to the dark sector of the theory determined by $\Omega_{\rm DM}\equiv [\Omega_{\rm DM}(\rm nuggets)+ \Omega_{\rm DM}(\rm axion)]$. We argue that the nugget's DM component always traces the visible matter density, i.e. $\Omega_{\rm DM}(\rm nuggets)\sim\Omega_{\rm visible}$ and this feature is not sensitive to the parameters of the system such as the axion mass $m_a$ or the misalignment angle $\theta_0$. It should be contrasted with conventional axion production mechanism due to the misalignment when $\Omega_{\rm DM}(\rm axion)$ is highly sensitive to the axion mass $m_a$ and the initial misalignment angle $\theta_0$. We also discuss the constraints on this model related to the inflationary scale $H_I$, non-observation of the isocurvature perturbations, $r_T < 0.12$, and also, varies axions search experiments.
Phenomenology of hydromagnetic turbulence in a uniformly expanding medium

A simple phenomenology is developed for the decay and transport of turbulence in a constant-speed, uniformly expanding medium. The fluctuations are assumed to be locally incompressible, and either of the hydrodynamic or non-Alfvénic magnetohydrodynamic (MHD) type. In order to represent local effects of nonlinearities, a simple model of the Kaármá-Dryden type for locally homogeneous turbulent decay is adopted. A detailed discussion of the parameters of this familiar one-point hydrodynamic closure is given, which has been shown recently to be applicable to non-Alfvénic MHD as well. The effects of the large-scale flow and expansion are incorporated using a two-scale approach, in which assumptions of particular turbulence symmetries provide simplifications. The derived model is tractable and provides a basis for understanding turbulence in the outer heliosphere, as well as in other astrophysical applications.
Anomalous scaling and universality in hydrodynamic systems with power-law forcing

The problem of the interplay between normal and anomalous scaling in turbulent systems stirred by a random forcing with a power law spectrum is addressed. We consider both linear and nonlinear systems. As for the linear case, we study passive scalars advected by a 2 d velocity ﬁeld in the inverse cascade regime. For the nonlinear case, we review a recent investigation of 3 d Navier-Stokes turbulence, and we present new quantitative results for shell models of turbulence. We show that to get ﬁrm statements is necessary to reach considerably high resolutions due to the presence of unavoidable subleading terms aﬀecting all correlation functions. All ﬁndings support universality of anomalous scaling for the small scale ﬂuctuations.
Proper-Motion Measurements of Pulsar B1951+32 in the Supernova Remnant CTB 80

Using the Very Large Array and the Pie Town antenna, we have measured the position of the radio pulsar B1951+32 relative to nearby background radio sources at four epochs between 1989 and 2000. These data show a clear motion for the pulsar of 25 ± 4 mas yr-1 at a position angle 252° ± 7° (north through east), corresponding to a transverse velocity 240 ± 40 km s-1 for a distance to the source of 2 kpc. The measured direction of motion confirms that the pulsar is moving away from the center of its associated supernova remnant, the first time that such a result has been demonstrated. Independent of assumptions made about the pulsar birthplace, we show that the measured proper motion implies an age for the pulsar of 64 ± 18 kyr, somewhat less than its characteristic age of 107 kyr. This discrepancy can be explained if the initial spin period of the pulsar was P0 = 27 ± 6 ms.
The PDS 110 observing campaign – photometric and spectroscopic observations reveal eclipses are aperiodic

PDS 110 is a young disc-hosting star in the Orion OB1A association. Two dimming events of similar depth and duration were seen in 2008 (WASP) and 2011 (KELT), consistent with an object in a closed periodic orbit. In this paper, we present data from a ground-based observing campaign designed to measure the star both photometrically and spectroscopically during the time of predicted eclipse in 2017 September. Despite high-quality photometry, the predicted eclipse did not occur, although coherent structure is present suggesting variable amounts of stellar flux or dust obscuration. We also searched for radial velocity (RV) oscillations caused by any hypothetical companion and can rule out close binaries to 0.1Ms. A search of Sonneberg plate archive data also enabled us to extend the photometric baseline of this star back more than 50 yr, and similarly does not re-detect any deep eclipses. Taken together, they suggest that the eclipses seen in WASP and KELT photometry were due to aperiodic events. It would seem that PDS 110 undergoes stochastic dimmings that are shallower and of shorter duration than those of UX Ori variables, but may have a similar mechanism.
Path-integral Monte Carlo simulations for interacting few-electron quantum dots with spin-orbit coupling

We develop path-integral Monte Carlo simulations for a parabolic two-dimensional (2D) quantum dot containing $N$ interacting electrons in the presence of Dresselhaus and/or Rashba spin-orbit couplings. Our method solves in a natural way the spin contamination problem and allows for numerically exact finite-temperature results at weak spin-orbit coupling. For $N<10$ electrons, we present data for the addition energy, the particle density, and the total spin $S$ in the Wigner molecule regime of strong Coulomb interactions. We identify magic numbers at N=3 and N=7 via a peak in the addition energy. These magic numbers differ both from weak-interaction and classical predictions, and are stable with respect to (weak) spin-orbit couplings.
Dynamics of Team Learning Behaviours: The Effect of Time and Team Culture

This research study focused on team learning behaviours, particularly the extent to which teams use learning behaviours over time, as well as the influence of different team cultures on learning behaviours over time. Data from 33 university project teams were collected longitudinally at three moments (beginning, halfway point, and end of the project) and the analysis was conducted through growth modelling. A linear relationship between time and team learning through experimenting behaviour was found, suggesting that experimenting behaviour tends to increase over time in project teams. Moreover, the early development of team cultures that promote mutual understanding and good interpersonal relationships, the accomplishment of objectives, flexibility, and the search for alternative ways to perform tasks/problem solving are conducive to experimenting behaviours from the beginning of the teamwork. This study highlights the relevance of the temporal dynamics of team learning behaviours and their interaction with team culture.
Globular Cluster Population of Hickson Compact Group 22a and 90c

We present the first measurement of the globular cluster populations of galaxies in Hickson compact groups, in order to investigate the effect of these high-density environments on the formation and evolution of globular cluster systems. Based on V- and R-band images that we obtained of HCG 22a and HCG 90c with the ESO New Technology Telescope (NTT), we find a total globular cluster population of 1590 ± 854 for HCG 22a and 2136 ± 718 for 90c. The specific frequency was found to be SN = 1.9 ± 1.0 for HCG 22a and SN = 3.4 ± 1.1 for HCG 90c. A power-law fit to the globular cluster radial profile of HCG 22a yields σ ~ R-2.01±0.30, and for HCG 90c we found σ ~ R-1.20±0.16. A comparison of the globular cluster radial profiles with the surface brightness of the parent galaxy shows that the globular cluster systems are at least as extended as the halo light. The measured values for the specific frequency are consistent with a scenario in which the host galaxies were in a low-density "fieldlike" environment when they formed their globular cluster systems.
Room-temperature observation and current control of skyrmions in Pt/Co/Os/Pt thin films

We report the observation of room-temperature magnetic skyrmions in Pt/Co/Os/Pt thin-film heterostructures and their response to electric currents. The magnetic properties are extremely sensitive to inserting thin Os layers between the Co-Pt interface resulting in reduced saturation magnetization, magnetic anisotropy and Curie temperature. The observed skyrmions exist in a narrow temperature, applied-field and layer-thickness range near the spin-reorientation transition from perpendicular to in-plane magnetic anisotropy. The skyrmions have an average diameter of 2.3{\mu}m and transport measurements demonstrate these features can be displaced with current densities as low as J = 2x10^4 A/cm^2 and display a skyrmion Hall effect.
Cosmological Spinning Multi-'Black-Hole' Solution in String Theory

We give a cosmological spinning multi-‘black-hole’ solution in the Einstein-Maxwelldilaton-axion theory with a positive cosmological constant. This solution is the cosmological dilatonic Israel-Wilson-Perjes solution and describes the collision of several spinning ‘blackholes’. A cosmological multi-black hole solution has been discovered by Kastor and Traschen 1) (KT solution) in the Einstein-Maxwell theory with a positive cosmological constant Λ (EM-Λ). The solution describes collisions of several black holes (BHs) in asymptotically de Sitter space-times. It is worth noting that the solution is the first exact solution that describes the BH-BH collision. It also provides a test of the cosmic censorship 2),3) and cosmic no-hair conjectures 4) in the inflationary universe. 5) One may be greatly interested in the spinning version of the KT solution because the rotating cases are generic. Apart from the cosmological cases, the spinning multisoliton solution was found by Israel and Wilson 6) and Perjes 7) (IWP solution) in asymptotically flat space-times. Unfortunately, the solution has naked singularities due to the force balance condition Q = M. On the other hand, we can expect that there are cases without singularities in asymptotically de Sitter space-times even if Q = M. This expectation is based on the causal structure of the single KerrNewman-de Sitter space-time. Thus we can obtain the physical advantage of the cosmological version due to the fact that there is no singularity. The existence of the spinning multi-soliton solution is deeply related to the force balance up to the gravitational spin-spin interaction. The force cancellation has been confirmed for the IWP solution. 8) The present author and Gen also showed that the force cancellation holds between a probe particle and the Kerr-Newman-de Sitter space-time. 9) This observation strongly encourages us to find a new cosmological spinning multi-black-hole solution, that is, the spinning version of the KT solution. In this paper, however, we give an exact solution in the four-dimensional EinsteinMaxwell-dilaton-axion (EMDA) theory with a positive Λ (EMDA-Λ) which describes a low energy string theory, except for a positive Λ. The construction of the solution is motivated by the chiral null model 10) in five dimensions. In the four-dimensional EMDA theory, without the cosmological constant, there is the dilatonic IWP so
Psychological impacts of COVID-19 on parenting and child behavior in Brazilian families: mediation effects of parental positive mental health

This study aimed to investigate the psychological impacts of the COVID-19 pandemic on parental positive mental health, parenting and child’s behavior. Participants were 150 parents, mostly women (82.0 %), with a mean age of 38 years (SD = 5.4), mothers of children varying between 3 and 11 years of age (M = 6.1; SD = 2.5). Our path analysis model presented a good fit considering the indirect impacts of COVID-19 on parenting and child behaviors through the direct effect on parental mental health. The psychological impacts of the COVID-19 pandemic had a mediated effect through the parents’ mental health on the child’s behavior; however, it had no significant effect on parenting. Our results confirm some expectations reported by Brazilian and international researchers, who predicted impairments in the daily lives of families and the behavior of children during the period of social isolation.
Guided Waves on Scalar and Tensorial Reactance Surfaces Modulated by Periodic Functions: A Circuital Approach

A technique to derive the propagation characteristics and field distributions of waves guided by a scalar and tensorial reactance surfaces modulated by periodic or discrete Fourier spectrum functions in the propagation direction is presented. The method based on an equivalent lumped circuits approach can be seen as a generalization of Oliner’s method for the TM propagation on scalar sinusoidally modulated reactance surfaces. The numerical results are obtained for both surface wave and leaky wave solutions. The relevance of these studies to modulated metasurface antennas is discussed.
Real-time handling of existing content sources on a multi-layer display

A Multi-Layer Display (MLD) consists of two or more imaging planes separated by physical depth where the depth is a key component in creating a glasses-free 3D effect. Its core benefits include being viewable from multiple angles, having full panel resolution for 3D effects with no side effects of nausea or eye-strain. However, typically content must be designed for its optical configuration in foreground and background image pairs. A process was designed to give a consistent 3D effect in a 2-layer MLD from existing stereo video content in real-time. Optimizations to stereo matching algorithms that generate depth maps in real-time were specifically tailored for the optical characteristics and image processing algorithms of a MLD. The end-to-end process included improvements to the Hierarchical Belief Propagation (HBP) stereo matching algorithm, improvements to optical flow and temporal consistency. Imaging algorithms designed for the optical characteristics of a MLD provided some visual compensation for depth map inaccuracies. The result can be demonstrated in a PC environment, displayed on a 22” MLD, used in the casino slot market, with 8mm of panel seperation. Prior to this development, stereo content had not been used to achieve a depth-based 3D effect on a MLD in real-time
On supersymmetry breaking in string theory from gauge theory in a throat

We embed the supersymmetry breaking mechanism in = 1 SQCD of hep-th/0602239 in a smooth superstring theory using D-branes in the background 4 × SL(2)k = 1/U(1) which smoothly captures the throat region of an intersecting NS5-brane configuration. A controllable deformation of the supersymmetric branes gives rise to the mass deformation of the magnetic SQCD theory on the branes. The consequent instability on the open string worldsheet can be followed onto a stable non-supersymmetric configuration of D-branes which realize the metastable vacuum configuration in the field theory. The new brane configuration is shown to backreact onto the background such as to produce different boundary conditions for the string fields in the radial direction compared to the supersymmetric configuration. In the string theory, this is interpreted to mean that the supersymmetry breaking is explicit rather than spontaneous.
Cosmology with XMM galaxy clusters: the X-CLASS/GROND catalogue and photometric redshifts

The XMM Cluster Archive Super Survey (X-CLASS) is a serendipitously-detected X-ray-selected sample of 845 galaxy clusters based on 2774 XMM archival observations and covering approximately 90 deg$^2$ spread across the high-Galactic latitude ($|b|>20$ deg) sky. The primary goal of this survey is to produce a well-selected sample of galaxy clusters on which cosmological analyses can be performed. This article presents the photometric redshift followup of a high signal-to-noise subset of 266 of these clusters with declination $\delta<+20$ deg with GROND, a seven channel ($grizJHK$) simultaneous imager on the MPG 2.2m telescope at the ESO La Silla Observatory. We use a newly developed technique based on the red sequence colour-redshift relation, enhanced with information coming from the X-ray detection to provide photometric redshifts for this sample. We determine photometric redshifts for 236 clusters, finding a median redshift of $z=0.39$ with an accuracy of $\Delta z = 0.02 (1+z)$ when compared to a sample of 76 spectroscopically confirmed clusters. We also compute X-ray luminosities for the entire sample and find a median bolometric luminosity of $7.2\times10^{43} \mathrm{erg\ s^{-1}}$ and a median temperature 2.9 keV. We compare our results to the XMM-XCS and XMM-XXL surveys, finding good agreement in both samples. The X-CLASS catalogue is available online at this http URL.
A global study of type B quasi-periodic oscillation in black hole X-ray binaries

We performed a global study on the timing and spectral properties of type-B quasi-periodic oscillations (QPOs) in the outbursts of black hole X-ray binaries. The sample is built based on the observations of Rossi X-ray Timing Explorer (RXTE), via searching in the literature in RXTE era for all the identified type-B QPOs. To enlarge the sample, we also investigated some type-B QPOs that are reported but not yet fully identified. Regarding to the time lag and hard/soft flux ratio, we found that the sources with type-B QPOs behave in two subgroups. In one subgroup, type-B QPO shows a hard time lag that first decreases and then reverse into a soft time lag along with softening of the energy spectrum. In the other subgroup, type-B QPOs distribute only in a small region with hard time lag and relatively soft hardness. These findings may be understood with a diversity of the homogeneity showing up for the hot inner flow of different sources. We confirm the universality of a positive relation between the type-B QPO frequency and the hard component luminosity in different sources. We explain the results by considering that the type-B QPO photons are produced in the inner accretion flow around the central black hole, under a local Eddington limit. Using this relationship, we derived a mass estimation of 9.3–27.1 M_⊙ for the black hole in H 1743−322.
Efficient and Secure Skyline Queries Over Vertical Data Federation

Skyline is a primitive operation in multi-objective decision applications and there is a growing demand to support such operations over a data federation, where the entire dataset is separately held by multiple data providers (a.k.a., silos). Data federations notably increase the amount of data available for data-intensive applications such as commercial recommendation and location based services. Yet they also challenge the conventional implementation of skyline queries because the raw data cannot be shared within the federation and the secure computation cross silos can be two or three orders of magnitude slower than plaintext computation. These constraints render existing solutions inefficient on data federation. In this work, we propose a novel local dominance based framework for efficient skyline queries over a vertical data federation. We decompose the skyline query into plaintext local dominance computations and secure result aggregations, which can perform as many computations in plaintext as possible without compromising security. We further propose a dedicate private set intersection based algorithm to accelerate the query processing. Extensive evaluations on both synthetic and real-world datasets show that compared with general-purpose secure multi-party computation techniques, our solutions reduce the time cost by up to 35.4× and communication cost by two orders of magnitude respectively.
Toward underwater image enhancement: new dataset and white balance priors-based fusion network

Abstract. Raw underwater images are degraded due to light attenuation and particle scattering. It is challenging to obtain authentic reference images. Hence, existing underwater datasets may be short of paired and trainable images. Many data-driven approaches are therefore difficult to implement. To address the above issues, we mainly make two contributions. First, a paired artificial underwater dataset (i.e., PAU-Wild) is constructed, including more than 3500 pairs of images of seven types. PAU-Wild is the first attempt to simulate real-world underwater images with external filters. Second, to enhance underwater images, a convolutional neural network using multistage fusion is proposed. Our model introduces two white balance (WB) priors into the fusion strategy. In addition, a joint loss function is designed to preserve content features and edge features. The experimental results demonstrate that our method is effective and even outperforms several state-of-the-art methods.
Glasslike low-frequency ac response of ZrB 12 and Nb single crystals in the surface superconducting state

We report experimental studies of the low frequency electrodynamics of ZrB$_{12}$ and Nb single crystals. AC susceptibility at frequencies 3 - 1000 Hz have been measured under a dc magnetic field, $H_0$, applied parallel to the sample surface. In the surface superconducting state, for several $H_0$, the real part of the ac magnetic susceptibility exhibits a logarithmic frequency dependence as for spin-glass systems. Kramers-Kronig analysis of the experimental data, shows large losses at ultra low frequencies ($<3$ Hz). The wave function slope at the surface was found. The linear response of the order parameter to the ac excitation was extracted from the experimental data.
Deep Learning of truncated singular values for limited view photoacoustic tomography

We develop a data-driven regularization method for the severely ill-posed problem of photoacoustic image reconstruction from limited view data. Our approach is based on the regularizing networks that have been recently introduced and analyzed in [J. Schwab, S. Antholzer, and M. Haltmeier. Big in Japan: Regularizing networks for solving inverse problems (2018), arXiv:1812.00965] and consists of two steps. In the first step, an intermediate reconstruction is performed by applying truncated singular value decomposition (SVD). In order to prevent noise amplification, only coefficients corresponding to sufficiently large singular values are used, whereas the remaining coefficients are set zero. In a second step, a trained deep neural network is applied to recover the truncated SVD coefficients. Numerical results are presented demonstrating that the proposed data driven estimation of the truncated singular values significantly improves the pure truncated SVD reconstruction. We point out that proposed reconstruction framework can straightforwardly be applied to other inverse problems, where the SVD is either known analytically or can be computed numerically.