Miracle-dz/UniFAR-FTUs huggingface dataset:
THE PHYSICS OF PROTOPLANETESIMAL DUST AGGLOMERATES. VI. EROSION OF LARGE AGGREGATES AS A SOURCE OF MICROMETER-SIZED PARTICLES

Observed protoplanetary disks consist of a large amount of micrometer-sized particles. Dullemond & Dominik pointed out for the first time the difficulty in explaining the strong mid-infrared excess of classical T Tauri stars without any dust-retention mechanisms. Because high relative velocities in between micrometer-sized and macroscopic particles exist in protoplanetary disks, we present experimental results on the erosion of macroscopic agglomerates consisting of micrometer-sized spherical particles via the impact of micrometer-sized particles. We find that after an initial phase, in which an impacting particle erodes up to 10 particles of an agglomerate, the impacting particles compress the agglomerate's surface, which partly passivates the agglomerates against erosion. Due to this effect, the erosion halts for impact velocities up to ∼30 m s−1 within our error bars. For higher velocities, the erosion is reduced by an order of magnitude. This outcome is explained and confirmed by a numerical model. In a next step, we build an analytical disk model and implement the experimentally found erosive effect. The model shows that erosion is a strong source of micrometer-sized particles in a protoplanetary disk. Finally, we use the stationary solution of this model to explain the amount of micrometer-sized particles in the observational infrared data of Furlan et al.
A comparative study of the influence of shift factor equations on master curve construction

This paper evaluates the applicability of different shifting techniques for constructing complex modulus master curves using the time-temperature superposition principle (TTSP). A database of complex modulus results of unmodified bitumens, polymer modified bitumens (PMBs), bitumen-filler mastics, unaged and aged bitumens was used together with a Generalized Logistic Sigmoidal Model to assess the validity of seven different shifting approaches. Except for the Laboratoire Central des Ponts et Chaussees (LCPC) method, the construction of master curves was done using the Generalised Logistic Sigmoidal Model and non-linear least squares regression optimization with the aid of the Microsoft Excel Spreadsheet Solver function. The goodness-of-fit for the various shifting techniques and functions was assessed through graphical and statistical methods. From the study, it was found that a numerical shift approach using non-linear least squares produced the best fit between experimental and predicted data in terms of both graphical and goodness-of-fit statistics. The ranking of the other shifting techniques consisted of the LCPC approach, followed by the William, Landel and Ferry (WLF), Modified Kaelble, Viscosity Temperature Susceptibility (VTS), Arrhenius and Log-Linear methods. However, most of the equations are basically empirical and they are not expected to be strictly obeyed by any materials. Discrepancies were still evident, even for the better functions, for those materials that demonstrated a deviation from the thermorheological simplicity of the rheological behaviour as found for highly structured bitumens following high degrees of polymer modification and/or oxidative ageing.
How are Mathematical Objects Constituted? A Structuralist Answer

In my view, structuralism as presented by Shapiro (1991, 1997), Resnik(1991), and elsewhere oﬀers the most plausible philosophy of mathematics:Mathematics is about structures, indeed it is the science of pure structures.Structures have no mysterious ontological status, and hence mathematicsis not ontologically mysterious, either. Again, it is no mystery how we canacquire knowledge about structures and thus mathematical knowledge. Weﬁnd structures everywhere. Hence, if mathematics is about structures, wecan apply mathematics everywhere. In this way, structuralism promises tooﬀer straightforward answers to the most pressing problems in the philo-sophy of mathematics.However, there are not only structures, there are also mathematical ob-jects, numbers, pairs, triangles, sets, etc. Concerning their nature, struc-turalism tends to metaphorics, the most preferred metaphor being thatmathematical objects are places in mathematical structures. Maybe it isnot really necessary to say more, since it is only the structures that reallymatter. Still, I think one should be explicit and precise about mathema-tical objects, and this is what this paper is intended to achieve. I tend tothink that the amendment it adds to structuralism is both trivial and ob-ligatory. Maybe, though, it is contested and hence of substantial interest.In order to say what mathematical objects are one needs to have aconception of general ontology. I shall present such a conception very sket-chily in section 1, just as much as to able to explain my preferred versionof Leibniz’ principle in section 2, which will become important when I amgoing to present and defend in section 3 how I think that mathematicalobjects are constituted.
A NEW OPTICAL SURVEY OF SUPERNOVA REMNANT CANDIDATES IN M31

We present a survey of optically emitting supernova remnants (SNRs) in M31 based on Hα and [S ii] images in the Local Group Survey. Using these images, we select objects that have [S ii]:Hα > 0.4 and circular shapes. We identify 156 SNR candidates, of which 76 are newly found objects. We classify these SNR candidates according to two criteria: the SNR progenitor type (Type Ia and core-collapse (CC) SNRs) and the morphological type. Type Ia and CC SNR candidates make up 23% and 77%, respectively, of the total sample. Most of the CC SNR candidates are concentrated in the spiral arms, while the Type Ia SNR candidates are rather distributed over the entire galaxy, including the inner region. The CC SNR candidates are brighter in Hα and [S ii] than the Type Ia SNR candidates. We derive a cumulative size distribution of the SNR candidates, finding that the distribution of the candidates with 17 <D < 50 pc is fitted well by a power law with the power-law index α = 2.53 ± 0.04. This indicates that most of the SNR candidates identified in this study appear to be in the Sedov–Taylor phase. The [S ii]:Hα distribution of the SNR candidates is bimodal, with peaks at [S ii]:Hα ∼ 0.4 and ∼0.9. The properties of these SNR candidates vary little with the galactocentric distance. The Hα and [S ii] surface brightnesses show a good correlation with the X-ray luminosity of the SNR candidates that are center-bright.
A SEARCH FOR PLANETARY ECLIPSES OF WHITE DWARFS IN THE Pan-STARRS1 MEDIUM-DEEP FIELDS

We present a search for eclipses of ∼1700 white dwarfs (WDs) in the Pan-STARRS1 medium-deep fields. Candidate eclipse events are selected by identifying low outliers in over 4.3 million light curve measurements. We find no short-duration eclipses consistent with being caused by a planetary size companion. This large data set enables us to place strong constraints on the close-in planet occurrence rates around WDs for planets as small as 2 R⊕. Our results indicate that gas giant planets orbiting just outside the Roche limit are rare, occurring around less than 0.5% of WDs. Habitable-zone super-Earths and hot super-Earths are less abundant than similar classes of planets around main-sequence stars. These constraints provide important insight into the ultimate fate of the large population of exoplanets orbiting main-sequence stars.
Resolved [CII] emission in a lensed quasar at z = 4.4

We present one of the first resolved maps of the [CII] 158 µm line, a powerful tracer of the star forming inter-stellar m edium, at high redshift. We use the new IRAM PdBI receivers at 350 GHz to map this line in BRI 0952-0115, the host galaxy of a lensed quasar at z=4.4 previously found to be very bright in [CII] emission. The [CII] emission is clearly resolved and our data allow us to resolve two [CII] lensed images associated with the optical quasar images. We find that the star formation, as traced by [CII], is dist ributed over a region of about 1 kpc in size near the quasar nucleus, and we infer a star formation surface density& 150 M⊙ yr −1 kpc −2 , similar to that observed in local ULIRGs. We also reveal another [CII] component, extended over∼12 kpc, and located at about 10 kpc from the quasar. We suggest that this component is a companion disk galaxy, in the process of merging with the quasar host, whose rotation field is distorted by the interaction with the quasa r host, and where star formation, although intense, is more diffuse. These observations suggest that galaxy merging at high-z can enhance star formation at the same time in the form of more compact regions, in the vicinity of the accreting black hole, and in more extended star forming galaxies.
Synchrotron X-ray diagnostics of cutoff shape of nonthermal electron spectrum at young supernova remnants

Synchrotron X-rays can be a useful tool to investigate electron acceleration at young supernova remnants (SNRs). At present, since the magnetic field configuration around the shocks of SNRs is uncertain, it is not clear whether electron acceleration is limited by SNR age, synchrotron cooling, or even escape from the acceleration region. We study whether the acceleration mechanism can be constrained by the cutoff shape of the electron spectrum around the maximum energy. We derive analytical formulae of the cutoff shape in each case where the maximum electron energy is determined by SNR age, synchrotron cooling and escape from the shock. They are related to the energy dependence of the electron diffusion coefficient. Next, we discuss whether information on the cutoff shape can be provided by observations in the near future which will simply give the photon indices and the flux ratios in the soft and hard X-ray bands. We find that if the power-law index of the electron spectrum is independently determined by other observations, then we can constrain the cutoff shape by comparing theoretical predictions of the photon indices and/or the flux ratios with observed data which will be measured by NuSTAR and/or ASTRO-H. Such study is helpful in understanding the acceleration mechanism. In particular, it will supply another independent constraint on the magnetic field strength around the shocks of SNRs.
Role of Family Acculturation Stress in Career Development Among Adolescents From Multicultural Families in Korea

Career indecision is a substantial challenge for multicultural adolescents in South Korea. This study investigated the role of acculturation stress in adolescents and their parents in multicultural families on career decisions in South Korea. Perceived career barriers by adolescents and career-related behaviors of their parents were included as mediators. Using national panel data from 1695 cases longitudinally collected over the 3 years, the mediation analysis was conducted. The results showed that acculturation stress experienced by both adolescents and parents negatively predicted the adolescents’ career decisions. In addition, a sequential mediation effect of parental career-related behaviors and adolescents’ career barriers was found in the relationship between parental acculturation stress and adolescents’ career decisions. These results highlight the importance of acculturative stress experienced by families, and not just by individuals, in understanding the career development of multicultural adolescents. The implications of this study’s findings are discussed.
Six-Minute Walking Test and 30 Seconds Chair-Stand-Test as Predictors of Mortality in COPD – A Cohort Study

Background Physical inactivity is strongly associated with worse prognosis in Chronic Obstructive Pulmonary Disease (COPD), and assessment of physical function is very important. The six minute walking test (6MWT) is an established test known to predict mortality in COPD, and 30 seconds chair stand test (30sCST) is a potential alternative test. The study aimed to investigate and compare the associations of 6MWT and 30sCSTs with mortality. Methods Data on patient demographics, established mortality predictors and results from 6MWT and 30sCST were collected from 2016 to 2019 from 97 consecutively included patients with COPD. In August 2021, mortality data were retrieved from patient records. Correlation analysis of 6MWT and 30sCST was performed. The predictive abilities of 6MWT and 30sCST, respectively, were analyzed using Kaplan Meyer-curves and Cox regression with adjustment for sex, age, body mass index below 22 and comorbid cardiovascular disease. Results A positive correlation between 6MWT and 30sCST was shown (r = 0.61, p < 0.0001). Independent associations with mortality were found for 6MWD 250–349 (HR (95% CI) 3.19 (1.12 to 9.10), p = 0.030) and 6MWD <250 (4.27 (1.69 to10.8), p = 0.002) compared with 6MWD ≥350 meters, and for 30sCST <4 (3.31 (1.03 to 10.6), p = 0.045) compared with 30sCST≥11 risings. When both 6MWT and 30sCST were included in the multivariable model, 6MWD 250–349 (3.09 (1.02 to 9.37), p = 0.046) and 6MWD <250 (3.57 (1.26 to 10.1), p = 0.016) compared with 6MWD ≥350 meters predicted mortality. Conclusion 30sCST and 6MWT correlates moderately and are independently associated with mortality in patients with COPD. Although 6MWT is the best predictor of mortality, 30sCST may be used as an alternative to identify patients at risk.
Clustering of Particles Falling in a Turbulent Flow

Spatial clustering of identical particles falling through a turbulent flow enhances the collision rate between the falling particles, an important problem in aerosol science. We analyze this problem using perturbation theory in a dimensionless parameter, the so-called Kubo number. This allows us to derive an analytical theory quantifying the spatial clustering. We find that clustering of small particles in incompressible random velocity fields may be reduced or enhanced by the effect of gravity (depending on the Stokes number of the particles) and may be strongly anisotropic.
Dark Matter through the Axion Portal

Motivated by the galactic positron excess seen by PAMELA and ATIC/PPB-BETS, we propose that dark matter is a TeV-scale particle that annihilates into a pseudoscalar 'axion'. The positron excess and the absence of an antiproton or gamma ray excess constrain the axion mass and branching ratios. In the simplest realization, the axion is associated with a Peccei-Quinn symmetry, in which case it has a mass around 360-800 MeV and decays into muons. We present a simple and predictive supersymmetric model implementing this scenario, where both the Higgsino and dark matter obtain masses from the same source of TeV-scale spontaneous symmetry breaking.
ournal of C osmology and A stroparticle hysics Unveiling the nature of dark matter with high redshift 21 cm line experiments

Observations of the redshifted 21 cm line from neutral hydrogen will open a new window on the early Universe. By inﬂuencing the thermal and ionization history of the intergalactic medium (IGM), annihilating dark matter (DM) can leave a detectable imprint in the 21 cm signal. Building on the publicly available 21cmFAST code, we compute the 21 cm signal for a 10 GeV WIMP DM candidate. The most pronounced role of DM annihilations is in heating the IGM earlier and more uniformly than astrophysical sources of X-rays. This leaves several unambiguous, qualitative signatures in the redshift evolution of the large-scale ( k ≈ 0 . 1 Mpc − 1 ) 21 cm power amplitude: (i) the local maximum (peak) associated with IGM heating can be lower than the other maxima; (ii) the heating peak can occur while the IGM is in emission against the cosmic microwave background (CMB); (iii) there can be a dramatic drop in power (a global minimum) corresponding to the epoch when the IGM temperature is comparable to the CMB temperature. These signatures are robust to astrophysical uncertainties, and will be easily detectable with second generation interferometers. We also brieﬂy show that decaying warm dark matter has a negligible role in heating the IGM.
Hard-thermal-loop corrections in leptogenesis I: CP-asymmetries

We investigate hard-thermal-loop (HTL) corrections to the CP-asymmetries in neutrino and, at high temperature, Higgs boson decays in leptogenesis. We pay special attention to the two leptonic quasiparticles that arise at non-zero temperature and find that there are four contributions to the CP-asymmetries, which correspond to the four combinations of the two leptonic quasiparticles in the loop and in the final states. In two additional cases, we approximate the full HTL-lepton propagator with a zero-temperature propagator that employs the thermal lepton mass ml(T), or the asymptotic thermal lepton mass (2)1/2 ml(T). We find that the CP-asymmetries in the one-mode approaches differ by up to one order of magnitude from the full two-mode treatment in the interesting temperature regime T ~ M1. The asymmetry in Higgs boson decays turns out to be two orders of magnitude larger than the asymmetry in neutrino decays in the zero-temperature treatment. The effect of HTL corrections on the final lepton asymmetry are investigated in paper II of this series.
Ergodic Achievable Rate Maximization of RIS-Assisted Millimeter-Wave MIMO-OFDM Communication Systems

Reconfigurable intelligent surface (RIS) has attracted extensive attention in recent years. However, most research focuses on the scenario of the narrowband and/or instantaneous channel state information (CSI), while wide bandwidth with the use of millimeter-wave (mmWave) (including sub-Terahertz) spectrum is a major trend in next-generation wireless communications, and statistical CSI is more practical to obtain in realistic systems. Thus, we consider the ergodic achievable rate of RIS-assisted mmWave multiple-input multiple-output orthogonal frequency division multiplexing communication systems. The widely used Saleh-Valenzuela channel model is adopted to characterize the mmWave channels and only the statistical CSI is available. We first derive the approximations of the ergodic achievable rate by means of the majorization theory and Jensen’s inequality. Then, an alternating optimization based algorithm is proposed to maximize the ergodic achievable rate by jointly designing the transmit covariance matrix at the base station and the reflection coefficients at the RIS. Specifically, the design of the transmit covariance matrix is transformed into a power allocation problem and solved by spatial-frequency water-filling. The reflection coefficients are optimized by the Riemannian conjugate gradient algorithm. Simulation results corroborate the effectiveness of the proposed algorithms.
Collision‐Induced Subduction Polarity Reversal Explains the Crustal Structure of Northern Borneo: New Results From Virtual Deep Seismic Sounding (VDSS)

Subduction polarity reversal (SPR) is a key subduction initiation mechanism often associated with arc‐continent collision zones. Northern Borneo has long been recognized as a location where sequential but opposing subduction zones were present in the Miocene, but has not been examined in the context of SPR. Here, we exploit teleseismic data from northern Borneo to investigate crustal thickness variations using Virtual Deep Seismic Sounding (VDSS). Our results reveal a thick crustal root beneath the Crocker Range and an area of relatively thin crust in the southeast, which appears to extend northeast into the Sulu Sea, where back‐arc rifting behind the younger subduction zone developed. Overall, our findings are consistent with predictions from numerical models of SPR involving arc‐continent collision, but with several important differences—including a substantial mountain range and more limited back‐arc rifting that can be attributed to northern Borneo being an example of SPR involving continent‐continent collision.
Oscillatory crossover from two-dimensional to three-dimensional topological insulators

We investigate the crossover regime from three-dimensional topological insulators ${\text{Bi}}_{2}{\text{Te}}_{3}$ and ${\text{Bi}}_{2}{\text{Se}}_{3}$ to two-dimensional topological insulators with quantum spin Hall effect when the layer thickness is reduced. Using both analytical models and first-principles calculations, we find that the crossover occurs in an oscillatory fashion as a function of the layer thickness, alternating between topologically trivial and nontrivial two-dimensional behavior.
Accelerating incoherent dedispersion

Incoherent dedispersion is a computationally intensive problem that appears frequently in pulsar and transient astronomy. For current and future transient pipelines, dedispersion can dominate the total execution time, meaning its computational speed acts as a constraint on the quality and quantity of science results. It is thus critical that the algorithm be able to take advantage of trends in commodity computing hardware. With this goal in mind, we present an analysis of the ‘direct’, ‘tree’ and ‘sub-band’ dedispersion algorithms with respect to their potential for efficient execution on modern graphics processing units (GPUs). We find all three to be excellent candidates, and proceed to describe implementations in c for cuda using insight gained from the analysis. Using recent CPU and GPU hardware, the transition to the GPU provides a speed-up of nine times for the direct algorithm when compared to an optimized quad-core CPU code. For realistic recent survey parameters, these speeds are high enough that further optimization is unnecessary to achieve real-time processing. Where further speed-ups are desirable, we find that the tree and sub-band algorithms are able to provide three to seven times better performance at the cost of certain smearing, memory consumption and development time trade-offs. We finish with a discussion of the implications of these results for future transient surveys. Our GPU dedispersion code is publicly available as a c library at http://dedisp.googlecode. com/.
Algebra for 8th Graders: Evidence on its Effects from 10 North Carolina Districts

This paper examines the effects of policies that increase the number of students who take the first course in algebra in 8th grade, rather than waiting until 9th grade. Extending previous research that focused on the Charlotte-Mecklenberg school system, we use data for the 10 largest districts in North Carolina. We identify the effects of accelerating the timetable for taking algebra by using data on multiple cohorts grouped by decile of prior achievement and exploiting the fact that policy-induced shifts in the timing of algebra occur at different times in different districts to different deciles of students. The expanded data make it possible to examine heterogeneity across students in the effect of taking algebra early. We find negative effects among students in the bottom 60% of the prior achievement distribution. In addition, we find other sources of heterogeneity in effects.