Miracle-dz/UniFAR-FTUs huggingface dataset:
Hyper-Temporal Data Based Modulation Transfer Functions Compensation for Geostationary Remote Sensing Satellites

Over the past years, the acquisition of hyper-temporal data (HTD) from geostationary orbit remote sensing satellites (GEORSS) has provided numerous new research opportunities. Many factors influence the in-orbit dynamic modulation transfer function (MTF) of GEORSS, making it difficult to satisfy the requirements for space-borne cameras. The MTF compensation (MTFC) technique can effectively optimize the design of dynamic MTFs for GEORSS. The traditional MTFC methods mainly consider the sensor, atmosphere and relative motion of the satellite platform when improving GEORSS image quality. They will introduce new high frequency noise, resulting in image information loss. In this article, a mixed sparse higher-order non-convex total variation (MS-HONCTV) model-aided MTFC method is proposed. By introducing the group sparse regularization (GSR) term into the MS-HONCTV model, it increases the robustness to noise and hence reduces the degeneration of the MTF produced by satellite’ low pointing stability. The MS-HONCTV model is then applied to solve the problem of image degradation. The quality of remote sensing (RS) data is improved by the proposed MTFC and this is achieved without modifying the aperture diameter, focal length, or detector size of the satellite’s optical system. Experimental results show that the proposed MS-HONCTV effectively improves the images’ MTF, SNR, gray mean gradient (GMG), and standard deviation (SD), as evidenced by subjective qualitative analysis and objective quantitative assessments of simulated data, laboratory data, and GF-4 satellite data. Compared with other methods, the SNR of the proposed method is increased by 30%, GMG by 14.21%, and SD by 6.3% on average.
The Nature of the Light Variation of the Unique Binary DK CVn

Abstract We present BVR observations of DK CVn from 2007 and 2008. We analysed the BVR light curves of the system and obtained the system's parameters. Using the ‘q-search’ method, we measured the mass ratio of the system (q) as 0.55. Taking the temperature of the primary component as 4040 K, the temperature of the secondary was found to be 3123 K. Several flares were detected, and the distributions of flare equivalent duration versus flare total duration were modelled using the One-Phase Exponential Association Function for these flares. The parameters of the model demonstrated that the flares are the same as those detected from UV Ceti stars. We also demonstrate that the variation at out-of-eclipse must be caused by some cool spot(s) on one of the components. The star is found to show two active longitudes in which the spots are mainly formed. Consequently, this study reveals that DK CVn should be a chromospherically active binary star.
Asteroseismology of Solar-Type Stars with K2: Detection of Oscillations in C1 Data

We present the first detections by the NASA K2 mission of oscillations in solar-type stars, using short-cadence data collected during K2 Campaign 1 (C1). We understand the asteroseismic detection thresholds for C1-like levels of photometric performance, and we can detect oscillations in subgiants having dominant oscillation frequencies around 1000 μHz. Changes to the operation of the fine-guidance sensors are expected to give significant improvements in the high-frequency performance from C3 onwards. A reduction in the excess high-frequency noise by a factor of 2.5 in amplitude would bring main-sequence stars with dominant oscillation frequencies as high as ≃2500 μHz into play as potential asteroseismic targets for K2.
Cluster membership probability: polarimetric approach

Interstellar polarimetric data of the six open clusters Hogg 15, NGC 6611, NGC 5606, NGC 6231, NGC 5749 and NGC 6250 have been used to estimate the membership probability for the stars within them. For proper-motion member stars, the membership probability estimated using the polarimetric data is in good agreement with the proper-motion cluster membership probability. However, for proper-motion non-member stars, the membership probability estimated by the polarimetric method is in total disagreement with the proper-motion cluster membership probability. The inconsistencies in the determined memberships may be because of the fundamental differences between the two methods of determination: one is based on stellar propermotion in space and the other is based on selective extinction of the stellar output by the asymmetric aligned dust grains present in the interstellar medium. The results and analysis suggest that the scatter of the Stokes vectors q(%) and u(%) for the proper-motion member stars depends on the interstellar and intra-cluster differential reddening in the open cluster. It is found that this method could be used to estimate the cluster membership probability if we have additional polarimetric and photometric information for a star to identify it as a probable member/non-member of a particular cluster, such as the maximum wavelength value (λmax), the unit weight error of the fit (σ1), the dispersion in the polarimetric position angles (ǫ), reddening (E(B V )) or the differential intra-cluster reddening (�E(B V )). This method could also be used to estimate the membership probability of known member stars having no membership probability as well as to resolve disagreements about membership among different proper-motion surveys (Dias et al. 2006, Baumgardt et al. 2000, Belikov et al. 1999, Tucholke et al. 1986, Berger 1982).
High energy particles with negative and positive energies in the vicinity of black holes

It is shown that the energy in the centre of mass frame of two colliding particles in free fall at any point of the ergosphere of the rotating black hole can grow without limit for fixed energy values of particles on infinity. The effect takes place for large negative values of the angular momentum of one of the particles. It occurs that the geodesics with negative energy in equatorial plane of rotating black holes cannot originate or terminate inside the ergosphere. Their length is always finite and this leads to conclusion that they must originate and terminate inside the gravitational radius of the ergosphere. The energy in the centre of mass frame of one particle falling into the gravitational radius and the other arriving from the area inside it is growing without limit on the horizon.
Defining urban and rural regions by multifractal spectrums of urbanization

The spatial pattern of urban-rural regional system is associated with the dynamic process of urbanization. How to characterize the urban-rural terrain using quantitative measurement is a difficult problem remaining to be solved. This paper is devoted to defining urban and rural regions using ideas from fractals. A basic postulate is that human geographical systems are of self-similar patterns associated with recursive processes. Then multifractal geometry can be employed to describe or define the urban and rural terrain with the level of urbanization. A space-filling index of urban-rural region based on the generalized correlation dimension is presented to reflect the degree of geo-spatial utilization in terms of urbanization. The census data of America and China are adopted to show how to make empirical analyses of urban-rural multifractals. This work is not so much a positive analysis as a normative study, but it proposes a new way of investigating urban and rural regional systems using fractal theory.
Inverse Hubble flows in molecular clouds

Motivated by recent numerical simulations of molecular cloud (MC) evolution, in which the clouds engage in global gravitational contraction, and local collapse events culminate significantly earlierthantheglobal collapse,weinvestigate thegrowthofdensityperturbations embedded in a collapsing background, to which we refer as an inverse Hubble flow (IHF). We use the standard procedure for the growth of perturbations in a universe that first expands (the usual Hubble flow) and then recollapses (the IHF). We find that linear density perturbations immersed in an IHF grow faster than perturbations evolving in a static background (the standard Jeans analysis). A fundamental distinction between the two regimes is that, in the Jeans case, the time τnl for a density fluctuation to become non-linear increases without limit as its initial value approaches zero, while in the IHF case τnl ≤ τff always, where τff is the freefall time of the background density. We suggest that this effect, although moderate, implies that small-scale density fluctuations embedded in globally collapsing clouds must collapse earlier than their parent cloud, regardless of whether the initial amplitude of the fluctuations is moderateorstronglynon-linear,thusallowingtheclassicalmechanismofHoylefragmentation to operate in multi-Jeans-mass MCs. More fundamentally, our results show that, contrary to the standard paradigm that fluctuations of all scales grow at the same rate in the linear regime, the hierarchical nesting of the fluctuations of different scales does affect their growth even in the linear stage.
Pulsar spin–velocity alignment: kinematic ages, birth periods and braking indices

This paper presents a detailed investigation of the dependence of pulsar spin-velocity alignment, which has been observed for a sample of 58 pulsars, on pulsar age. At first, our study considers only pulsar characteristic ages, resulting in no change in the degree of correlation as a function of age, up to at least 100 Myr. Subsequently, we consider a more reliable estimate of pulsar age, the kinematic age, assuming that pulsars are born near the Galactic plane. We derive kinematic ages for 52 pulsars, based on the measured pulsar proper motions and positions, by modelling the trajectory of the pulsars in a Galactic potential. The sample of 52 pulsar kinematic ages constitutes the largest number of independently estimated pulsar ages to date. Using only the 33 most reliable kinematic ages from our simulations, we revisit the evolution of spin- velocity alignment, this time as a function of kinematic age. We find that the strong correlation seen in young pulsars is completely smeared out for pulsars with kinematic ages above 10 Myr, a length of time beyond which we expect the gravitational pull of the Galaxy to have a significant effect on the directions of pulsar velocities. In the discussion, we investigate the impact of large distance uncertainties on the reliability of the calculated kinematic ages. Furthermore, we present a detailed investigation of the implications of our revised pulsar ages for the braking-index and birth-period distributions. Finally, we discuss the predictions of various SN-kick mechanisms and their compatibility with our results.
The effect of interictal epileptic discharges and following spindles on motor sequence learning in epilepsy patients

Purpose Interictal epileptic discharges (IEDs) are known to affect cognitive function in patients with epilepsy, but the mechanism has not been elucidated. Sleep spindles appearing in synchronization with IEDs were recently demonstrated to impair memory consolidation in rat, but this has not been investigated in humans. On the other hand, the increase of sleep spindles at night after learning is positively correlated with amplified learning effects during sleep for motor sequence learning. In this study, we examined the effects of IEDs and IED-coupled spindles on motor sequence learning in patients with epilepsy, and clarified their pathological significance. Materials and methods Patients undergoing long-term video-electroencephalography (LT-VEEG) at our hospital from June 2019 to November 2021 and age-matched healthy subjects were recruited. Motor sequence learning consisting of a finger-tapping task was performed before bedtime and the next morning, and the improvement rate of performance was defined as the sleep-dependent learning effect. We searched for factors associated with the changes in learning effect observed between the periods of when antiseizure medications (ASMs) were withdrawn for LT-VEEG and when they were returned to usual doses after LT-VEEG. Results Excluding six patients who had epileptic seizures at night after learning, nine patients and 11 healthy subjects were included in the study. In the patient group, there was no significant learning effect when ASMs were withdrawn. The changes in learning effect of the patient group during ASM withdrawal were not correlated with changes in sleep duration or IED density; however, they were significantly negatively correlated with changes in IED-coupled spindle density. Conclusion We found that the increase of IED-coupled spindles correlated with the decrease of sleep-dependent learning effects of procedural memory. Pathological IED-coupled sleep spindles could hinder memory consolidation, that is dependent on physiological sleep spindles, resulting in cognitive dysfunction in patients with epilepsy.
UNDERLYING GLOBAL FEATURES OF THE X-RAY LIGHT CURVES OF SWIFT GAMMA-RAY BURSTS

With its rapid response, Swift has revealed plenty of unexpected properties of gamma-ray bursts (GRBs). With an abundance of observations, our current understanding is only limited by the complexity of early X-ray light curves. In this work, based on the public Swift data of 150 well-monitored GRBs with measured redshifts, we find some interesting global features in the rest-frame X-ray light curves. The distinct spectral behaviors between the prompt emission and the afterglow emission imply dissimilar radiation scenarios. Interestingly, an unforeseen plateau is exhibited in the prompt X-ray light curves despite the presence of complex spikes, which might indicate the presence of a steady central engine. In particular, the seemingly continuous evolution with a single power law from the prompt to the afterglow of most GRBs might place strong constraints on the theoretical models.
Stability and anomalous compressibility of Bose gases near resonance: The scale-dependent interactions and thermal effects

The stability of Bose gases near resonance has been a puzzling problem in recent years. In this Letter, we demonstrate that in addition to generating thermal pressure, thermal atoms enhance the repulsiveness of the scale-dependent interactions between condensed atoms due to renormalization effect and further stabilize the Bose gases. Consequently, we find that, as a precursor of instability, the compressibility develops an anomalous structure as a function of scattering length and is drastically reduced compared with the mean-field value. Furthermore, the density profile of a Bose gas in a harmonic trap is found to develop a flat top near the center. This is due to the anomalous behavior of compressibility and can be a potential smoking gun for probing such an effect.
Relationship between EIT Posteruption Arcades, Coronal Mass Ejections, the Coronal Neutral Line, and Magnetic Clouds

There is observational evidence that the elongation of an Earth-directed coronal mass ejection (CME) may indicate the orientation of the underlying erupting flux rope. In this study, we compare orientations of CMEs, magnetic clouds (MCs), EIT (EUV Imaging Telescope) posteruption arcades, and the coronal neutral line (CNL). We report on good correlations between (1) the directions of the axial field in the EIT arcades and the elongations of halo CMEs, and (2) the tilt of the CNL and MC axis orientations. We found that majority of the eruptions that had EIT arcades, CMEs, and MCs similarly oriented also had the CNL co-aligned with them. On the other hand, those events that showed no agreement between orientations of the EIT arcades, CMEs, and MCs had their MCs aligned with the CNL. We speculate that the axis of the ejecta may be rotated in such a way that it is locally aligns itself with the heliospheric current sheet.
New frontiers in Numerical Relativity

The first attempts at solving a binary black hole spacetime date back to the 1960s, with the pioneering works of Hahn and Lindquist. In spite of all the computational advances and enormous efforts by several groups, the first stable, long-term evolution of the orbit and merger of two black holes was only accomplished over 40 years later, in 2005. Since then, the field of Numerical Relativity has matured, and been extensively used to explore and uncover a plethora of physical phenomena in various scenarios. In this thesis, we take this field to new frontiers by exploring its extensions to higher dimensions, non-asymptotically flat spacetimes and Einstein-Maxwell theory. We start by reviewing the usual formalism and tools, including the "3+1" decomposition, initial data construction, the BSSN evolution scheme and standard wave extraction procedures. We then present a dimensional reduction procedure that allows one to use existing numerical codes (with minor adaptations) to evolve higher-dimensional systems with enough symmetry, and show corresponding results obtained for five-dimensional head-on collisions of black holes. Finally, we show evolutions of black holes in non-asymptotically flat spacetimes, and in Einstein-Maxwell theory.
Tectonism of Late Noachian Mars: Surface Signatures from the Southern Highlands

Upwelling mantle plumes often instigate extensional stress within the continental crust of Earth. When stress exceeds crustal strength, extensional structures develop, reducing the effective stress and trigger magmatic processes at the crust–mantle boundary. However, such processes and their relationship to the formation of many surface structures remain poorly characterized on Mars. We identified a series of extensional structures in the southern highlands of Mars which collectively resemble continental rift zones on Earth. We further characterized these extensional structures and their surrounding region (area of ~1.8 M km2) by determining the surface mineralogy and bulk regional geochemistry of the terrain. In turn, this constrains their formation and yields a framework for their comparison with extensional structures on Earth. These terrains are notable for olivine and high-Ca pyroxene with a high abundance of potassium and calcium akin to alkali basalts. In the case of Mars, this Earth-like proto-plate tectonic scenario may be related to the plume-induced crustal stretching and considering their distribution and temporal relationship with the Hellas basin, we conclude that the plume is impact-induced. Overall, the findings of this work support the presence of mantle plume activity in the Noachian, as suggested by thermal evolution models of Mars.
M2-branes coupled to antisymmetric fluxes

By turning on antisymmetric background fluxes, we study how multiple M2-branes are coupled to them. Our investigation concentrates on the gauge invariance conditions for the Myers-Chern-Simons action. Furthermore, the dimensional reduction of M2-branes to D2-branes introduces more constraints on the newly introduced tensors. Particularly, for the theory based on A(4) algebra, we are able to fix all components of them up to an overall normalization constant. These results can not be simply obtained from the previously proposed cubic matrix representation for this algebra. We also comment on cubic matrices as the representations of 3-algebras.
Quintessence with Hybrid Potential

I present the numerical solution of equations of the evolution of a universe containing background fluids (radiation, dark matter and baryonic matter), plus a scalar matter field with a hybrid potential that is a combination of exponential potential and power-law potential. The plot of the evolution of density parameters is compatible with our universe; and today’s values of density parameters of dark energy, dark matter, baryonic matter, and Hubble parameter, and the age and size of our universe, found from this model, are very close to (and some times the same as) measured values.
Results from DROXO - III. Observation, source list, and X-ray properties of sources detected in the “Deep Rho Ophiuchi XMM-Newton Observation”

Context. X-rays from very young stars are powerful probes to investigate the mechanisms at work in the very first stages of the star formation and the origin of X-ray emission in very young stars. Aims. We present results from a 500 ks long observation of the Rho Ophiuchi cloud with a XMM-Newton large program named DROXO, aiming at studying the X-ray emission of deeply embedded young stellar objects (YSOs). Methods. The data acquired during the DROXO program were reduced with SAS software, and filtered in time and energy to improve the signal to noise of detected sources; light curves and spectra were obtained. Results. We detected 111 sources, 61 of them associated with ρ Ophiuchi YSOs as identified from infrared observations with ISOCAM. Specifically, we detected 9 out of 11 Class I objects, 31 out of 48 Class II and 15 out 16 Class III objects. Six objects out of 21 classified Class III candidates are also detected. At the same time we suggest that 15 Class III candidates that remain undetected at logLx [erg/s] < 28.3 are not related to the cloud population. The global detection rate is ∼64%. We have achieved a flux sensitivity of ∼5 × 10 −15 erg s −1 cm −2 . T heLX to Lbol ratio shows saturation at a value of ∼−3.5 for stars with Teff ≤ 5000 K or 0.7 M� as observed in the Orion Nebula. The plasma temperatures and the spectrum absorption show a decline with YSO class, with Class I YSOs being hotter and more absorbed than Class II and III YSOs. In one star (GY 266) with infrared counterpart in 2MASS and Spitzer catalogs we have detected a soft excess in the X-ray spectrum, which is best fitted by a cold thermal component less absorbed than the main thermal component of the plasma. This soft component hints at plasma heated by shocks due to jets outside the dense circumstellar material.
THE ELM SURVEY. III. A SUCCESSFUL TARGETED SURVEY FOR EXTREMELY LOW MASS WHITE DWARFS

Extremely low mass (ELM) white dwarfs (WDs) with masses < 0.25 M☉ are rare objects that result from compact binary evolution. Here, we present a targeted spectroscopic survey of ELM WD candidates selected by color. The survey is 71% complete and has uncovered 18 new ELM WDs. Of the seven ELM WDs with follow-up observations, six are short-period binaries and four have merger times less than 5 Gyr. The most intriguing object, J1741+6526, likely has either a pulsar companion or a massive WD companion making the system a possible supernova Type Ia or an Ia progenitor. The overall ELM survey has now identified 19 double degenerate binaries with <10 Gyr merger times. The significant absence of short orbital period ELM WDs at cool temperatures suggests that common envelope evolution creates ELM WDs directly in short period systems. At least one-third of the merging systems are halo objects, thus ELM WD binaries continue to form and merge in both the disk and the halo.
Splitting sensitivity of the ground and 7.6 eV isomeric states of {sup 229}Th

The lowest-known excited state in nuclei is the 7.6 eV isomer of {sup 229}Th. This energy is within the range of laser-based investigations that could allow accurate measurements of possible temporal variation of this energy splitting. This in turn could probe temporal variation of the fine-structure constant or other parameters in the nuclear Hamiltonian. We investigate the sensitivity of this transition energy to these quantities. We find that the two states are predicted to have identical deformations and thus the same Coulomb energies within the accuracy of the model (viz., within roughly 30 keV). We therefore find no enhanced sensitivity to variation of the fine-structure constant. In the case of the strong interaction the energy splitting is found to have a complicated dependence on several parameters of the interaction, which makes an accurate prediction of sensitivity to temporal changes of fundamental constants problematical. Neither the strong- nor Coulomb-interaction contributions to the energy splitting of this doublet can be constrained within an accuracy better than a few tens of keV, so that only upper limits can be set on the possible sensitivity to temporal variations of the fundamental constants.