Miracle-dz/UniFAR-FTUs huggingface dataset:
Rotation and Activity in Mid-M to L Field Dwarfs

We analyze rotation velocities and chromospheric (Hα) activity, derived from high-resolution spectra, in a large sample of mid-M to L field dwarfs. The projected rotation velocity is found to increase from mid-M to L. This is consistent with a lengthening of spin-down timescale with later type, although in the L types the trend may also be a function of the observational bias toward younger objects. From M4 to M8.5 a saturation-type rotation-activity relation is seen, similar to that in earlier types, when activity is measured through either FHα or LHα/Lbol. However, we find that activity saturates at a significantly higher velocity (~10 km s-1) in the M5.5-M8.5 dwarfs than in the M4-M5 ones (≲4 km s-1). This may result from a change in the dynamo behavior with later type (see also below). We note that the saturation level in Hα emission appears to vary somewhat less with spectral type (from M4 to M8.5) when activity is measured through LHα/Lbol instead of FHα. In M9 and later dwarfs, we observe a drastic drop in activity and a sharp break in the rotation-activity connection: Hα emission levels in these dwarfs are much lower than in earlier types, and often undetectable, in spite of very rapid rotation. This may be caused by the very high resistivities in the predominantly neutral atmospheres of these dwarfs, which would damp the magnetic energy available for supporting a chromosphere. It is also possible that the rapid formation of dust in these cool atmospheres exacerbates this effect, as charged particles are soaked up by (more massive) dust grains. Finally, we note that spectral type determination from low-resolution spectra may be affected by gravity effects: cooler, lower gravity objects may mimic hotter, higher gravity ones. Therefore, it is possible that the few unsaturated fast rotators from M5.5 to M8.5 (whose presence leads us to ascribe a higher saturation velocity to these spectral types, as noted above) may actually be very low mass objects, with lower Teff (and gravity) than their spectral types suggest. If so, their behavior (low activity, fast rotation) would be compatible with that of the cool M9 and later dwarfs (and no change in dynamo behavior would have to be postulated in the M5.5-M8.5 dwarfs). This interpretation is supported by a preliminary analysis of the high-resolution spectra of these anomolous objects. It is also bolstered by the fact that a saturation-type Rossby number-activity relation is seen in the M5.5-M8.5 dwarfs when these anomalous objects are removed from the sample, while the relationship is much weaker when they are included.
Scalar-tensor gravity in the Palatini approach

The main objective of this thesis is to discuss scalar-tensor theories in the Palatini approach. Both scalar-tensor theories and Palatini formalism are means of alternating classical theory of gravity, general relativity, in order to account for phenomena being seemingly unexplainable on the ground of the Einstein theory or to serve as toy models used to test limitations of the theory in question. In the literature, both Palatini approach and scalar-tensor theories have been widely discussed, but there are very few - if none - authors writing about a merge of these two ideas. The present paper is a result of an insufficient attention given to the topic of scalar-tensor theories in Palatini formalism. In the course of the thesis action functional for scalar-tensor theories of gravity will be introduced. This action functional differs significantly from the action defined in case of scalar-tensor theories in metric approach. We aim at analysing the theory using the language of invariants, allowing us to write down all equations in a frame-independent manner. We discover that invariants defined for the metric case do not always have their counterparts in Palatini formalism. Also, two frames most frequently used in the literature are discussed: Einstein and Jordan frame. Possible applications of the theory developed in the first part of the thesis are presented. We show the equivalence between $f(R)$ and scalar-tensor theories of gravity and exploit this fact by analysing the former using methods developed for scalar-tensor theories. We conclude the thesis with calculating the Friedmann equations for an empty universe of vanishing spatial curvature and preparing set-up for analysing inflationary behaviour.
Lensing Properties of Scale-free Galaxies

The multiple images of lensed quasars provide evidence on the mass distribution of the lensing galaxy. The lensing invariants are constructed from the positions of the images, their parities, and their fluxes. They depend only on the structure of the lensing potential. The simplest is the magnification invariant, which is the sum of the signed magnifications of the images. Higher order configuration invariants are the sums of products of the signed magnifications with positive or negative powers of the position coordinates of the images. We consider the case of the four- and five-image systems produced by elliptical power-law galaxies with ψ ∝ (x2 + y2q-2)β/2. This paper provides simple contour integrals for evaluating all their lensing invariants. For practical evaluation, this offers considerable advantages over the algebraic methods used previously. The magnification invariant is exactly B = 2/(2 - β) for the special cases β = 0, 1, and 4/3; for other values of β, this remains an approximation, but an excellent one at small source offset. Similarly, the sums of the first and second powers of the image positions (or their reciprocals), when weighted with the signed magnifications, are just proportional to the same powers of the source offset, with a constant of proportionality B. To illustrate the power of the contour integral method, we calculate full expansions in the source offset for all lensing invariants in the presence of arbitrary external shear. As an example, we use the elliptical power-law galaxies to fit to the data on the four images of the Einstein Cross (G2237+030). The lensing invariants play a role by reducing the dimensionality of the parameter space in which the χ2 minimization proceeds with consequent gains in accuracy and speed.
Group sequential clinical trials: a classical evaluation of Bayesian decision-theoretic designs

Abstract Bayesian decision-theoretic designs for a clinical trial comparing two treatments for a disease with binary outcomes are developed and evaluated. The probability of successful outcome with treatment i is denoted by pi , i = 1, 2, and prior knowledge regarding each pi is assumed to follow a beta distribution. The pi are assumed to be independent. To facilitate comparison with frequentist clinical trial designs, we take a hypothesis-testing approach. The null hypothesis is δ 0, where δ 0 is the minimum treatment effect sought by the trial and δ = p 2 - p 1 is the true treatment difference. We use a simple terminal loss function reflecting the hypothesis-testing goal of the trial, and the total cost of the trial is the final sample size plus the terminal loss function. The stopping and decision rules that minimize the expectation of the total cost are determined by backward induction. Monte Carlo simulation is used to compare Bayesian and frequentist erro.
The Thermodynamic Relationship between the RN-AdS Black Holes and the RN Black Hole in Canonical Ensemble

In this paper, by analyzing the thermodynamic properties of charged AdS black hole and asymptotically flat space-time charged black hole in the vicinity of the critical point, we establish the correspondence between the thermodynamic parameters of asymptotically flat space-time and nonasymptotically flat space-time, based on the equality of black hole horizon area in the two different types of space-time. The relationship between the cavity radius (which is introduced in the study of asymptotically flat space-time charged black holes) and the cosmological constant (which is introduced in the study of nonasymptotically flat space-time) is determined. The establishment of the correspondence between the thermodynamics parameters in two different types of space-time is beneficial to the mutual promotion of different time-space black hole research, which is helpful to understand the thermodynamics and quantum properties of black hole in space-time.
Branched circle packings and discrete Blaschke products

In this paper we introduce the notion of discrete Blaschke products via circle packing. We first establish necessary and sufficient conditions for the existence of finite branched circle packings. Next, discrete Blaschke products are defined as circle packing maps from univalent circle packings that properly fill D = {z: IzI < 1} to the corresponding branched circle packings that properly cover D. It is verified that such maps have all geometric properties of their classical counterparts. Finally, we show that any classical finite Blaschke product can be approximated uniformly on compacta of D by discrete ones.
About the Almeida-Thouless transition line in the Sherrington-Kirkpatrick mean-field spin glass model

We consider the Sherrington-Kirkpatrick model and we prove that the quenched free energy per spin is strictly larger than the corresponding replica symmetric approximation, for all values of the temperature and of the magnetic field below the Almeida-Thouless line. This implies the breaking of replica symmetry in the whole expected spin glass phase.
Exchange biasing by Ir19Mn81: Dependence on temperature, microstructure and antiferromagnetic layer thickness

We have investigated the thermal stability of the exchange biasing interaction in antiferromagnetic/ferromagnetic bilayers of Ir19Mn81 and Ni80Fe20 or Co90Fe10. The exchange-biasing field and the coercive field were found to depend strongly on the thickness of the Ir19Mn81 layer and on the crystallographic texture of the bilayer. The exchange-biasing field at room temperature has a maximum at 4 nm Ir19Mn81 layer thickness and then decreases for increasing Ir19Mn81 layer thickness. This coincides quite well with the thickness dependence of the (111) texture measured in Ir19Mn81 layers. Removing the Ta seed layer resulted in the disappearance of the (111) texture and at the same time the exchange-biasing field decreased for all Ir19Mn81 layer thicknesses. For films with a Ta seed layer and 8 nm Ir19Mn81 or more, we have found a blocking temperature of 560 K, decreasing with decreasing Ir19Mn81 layer thickness to around room temperature for 2 nm Ir19Mn81. Removing the Ta seed layer resulted in a decrease of the blocking temperature for all layer thicknesses investigated. We have concluded that the (111) texture is an important factor governing the size of the exchange-biasing field and the thermal stability.
COS-weak: Probing the CGM using analogues of weak Mg II absorbers at z < 0.3

NASA through Space Telescope Science Institute HST AR-12644 NASA NAS5-26555 European Research Council (ERC) 278594 Alfred P. Sloan Foundation U.S. Department of Energy Office of Science Center for High-Performance Computing at the University of Utah Brazilian Participation Group Carnegie Institution for Science, Carnegie Mellon University Chilean Participation Group French Participation Group Harvard-Smithsonian Center for Astrophysics Instituto de Astrofisica de Canarias Johns Hopkins University Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo Lawrence Berkeley National Laboratory Leibniz Institut fur Astrophysik Potsdam (AIP) Max-Planck-Institut fur Astronomie (MPIA Heidelberg) Max-Planck-Institut fur Astrophysik (MPA Garching) Max-Planck-Institut fur Extraterrestrische Physik (MPE) National Astronomical Observatories of China New Mexico State University New York University University of Notre Dame Observatario Nacional / MCTI Ohio State University Pennsylvania State University Shanghai Astronomical Observatory United Kingdom Participation Group Universidad Nacional Autonoma de Mexico University of Arizona University of Colorado Boulder University of Oxford University of Portsmouth University of Utah University of Virginia University of Washington University of Wisconsin Vanderbilt University Yale University
Worm-like instability of a vibrated sessile drop

We study the effects of vertical sinusoidal vibrations on a liquid droplet with a low surface tension (ethanol) deposited on a solid substrate. In a precise range of amplitudes and frequencies, the drop exhibits a dramatic worm-like shape instability with a strong symmetry breaking, comparable to the one observed by Pucci et al. (Phys. Rev. Lett., 106 (2011) 024503) on a vibrated floating lens. However, the geometry of our system is much simpler since it does not involve the oscillation and deformation of a liquid-liquid-air contact line. We show that the Faraday waves appearing on the surface of the droplet control its shape and we draw a systematic phase diagram of the instability. A simple theoretical model allows us to derive a relation between the elongation of the droplet and the amplitude of the Faraday wave, in good agreement with measurements of both quantities.
Thermal transport properties of synthetic porous solids as a function of applied pressure

The thermal conductivity, thermal diffusivity and specific heat per unit volume of three types of porous insulating solids were measured, simultaneously, by the transient plane source (TPS) technique. The samples, namely, fibreglass, closed-cell foam and foam insulation, were subjected to external pressure, taking into consideration the compressibility of the samples and the requirements of the TPS technique. These materials are used for insulation for temperature control of air-conditioned space and therefore are helpful in reducing energy losses. Although all three samples are good insulators, having very small thermal conductivity values (~0.03-0.05 W m-1 K-1), closed-cell foam insulation shows insignificant changes in thermal conductivity for the selected pressure range (8-15 kPa). Therefore it is a better choice for thermal isolation. For the other materials investigated, the thermal conductivity value increases slightly with external pressure.
Detecting topological invariants in chiral symmetric insulators via losses

We show that the bulk winding number characterizing one-dimensional topological insulators with chiral symmetry can be detected from the displacement of a single particle, observed via losses. Losses represent the effect of repeated weak measurements on one sublattice only, which interrupt the dynamics periodically. When these do not detect the particle, they realize negative measurements. Our repeated measurement scheme covers both time-independent and periodically driven (Floquet) topological insulators, with or without spatial disorder. In the limit of rapidly repeated, vanishingly weak measurements, our scheme describes non-Hermitian Hamiltonians, as the lossy Su-Schrieffer-Heeger model of Phys. Rev. Lett. 102, 065703 (2009). We find, contrary to intuition, that the time needed to detect the winding number can be made shorter by decreasing the efficiency of the measurement. We illustrate our results on a discrete-time quantum walk, and propose ways of testing them experimentally.
Short-Term Debris Risk to Large Satellite Constellations

A debris collision hazard analysis is carried out on a large 800-satellite constellation, representative of the initial Teledesic cone guration, using the Space Debris Simulation (SDS) software. Usage of the software focuses on the short- to medium-term effects of explosive and collision-induced breakups. Two potentially constellationthreatening scenarios are considered: 1 ) constellation member fragmentation and 2 ) constellation launch-vehicle breakup. The constellation collision probability and the debris impact-energy to target-mass ratio are used as indicatorsoftheseverityoftherisk posed totheconstellation.Itisfound that,inthecaseinvestigated,thecollisional risk to the constellation is low in the short term. Of the scenarios examined, it is the collision-induced breakup of a constellation satellite that poses the greatest danger, in terms of the possibility of a secondary fragmentation. The SDS software is proven to be a useful tool in the analysis of the short-term, relative threat posed by debris impact to large constellation systems.
Abundances for metal-poor stars with accurate parallaxes - II. $\alpha-$elements in the halo

Abundances for α−elements and Fe in about 150 field subdwarfs and early subgiants with accurate parallaxes and kinematic data are used to discuss the run of abundance ratios in metal-poor stars in the solar neighborhood. Based on kinematics, we separated stars into two populations: the first one has a positive velocity of rotation around the galactic center, and it is likely to be related to the dissipational collapse of the galaxy; the second one has either negligible or negative rotational velocity, and it is likely related to an accretion component. The two populations show a large overlap in metallicity. However, they show distinct chemical properties. For the first population we found that there are close correlations (with small scatters around) of the rotational velocity with metallicity and with the Fe/α abundance ratio: this might be a signature of a not very fast collapse of the progenitor clouds, with enough time for a significant contribution by SNe Ia, although this result needs to be confirmed by a 3-D/non-LTE study. On the other side, the second population exhibits a larger scatter in both the above mentioned relations, and on average, a larger Fe/α ratio at a given metallicity, suggesting a larger scatter in ages. We argue that the lack of stars with moderate rotational velocities and high Fe/α abundance ratios is due to the short merging time for protogalactic clouds with prograde motion, while the presence of a group of counter-rotating stars with this characteristics indicates a much longer typical lifetimes for protogalactic fragments having such a motion. Finally, we found that perigalactic distances correlate with the Fe/α abundance ratios better than the apogalactic distances.
Chandra Observations of NGC 4636—an Elliptical Galaxy in Turmoil

Chandra images show symmetric, 8 kpc long, armlike features in the X-ray halo surrounding NGC 4636. The leading edges of these features are sharp and are accompanied by temperature increases of ~30%. These properties suggest that the armlike structures are produced by shocks, driven by symmetric off-center outbursts. We interpret these observations as part of a cycle in which the cooling gas originally fueled a nuclear outburst about 3 × 106 yr ago that led to shocks reheating the cooling gas and thus preventing the accumulation of significant amounts of cooled gas in the galaxy center and temporarily starving the central active galactic nucleus.
Unconventional upper- and lower-critical fields and normal-state magnetic susceptibility of the superconducting compound Na 0.35 CoO 2 ⋅ 1.3 H 2 O

Magnetic properties of the layered superconductor, Na 0 . 3 5 CoO 2 . 1.3H 2 O have been investigated. From the temperature dependence and field dependence of the magnetization, the superconducting transition temperature, aswell as upper- and lower-critical fields have been estimated to be T C =4.6 K, H C 2 (0)=61.0 T and H C 1 (0)=28.1 Oe, respectively. These values give quite unusual phenomenological parameters, i.e., coherent length, penetration depth and Ginzburg-Landau parameter of Β=2.32 nm, λ=5.68×10 2 nm, and κ≡λ/Β =244, respectively, suggesting an unconventional nature of superconductivity. Additionally, the magnetic susceptibility above T C and the magnetization curve up to 54 T are also reported.
Meromorphic functions with three radially distributed values

We consider transcendental meromorphic functions for which the zeros, 1-points and poles are distributed on three distinct rays. We show that such functions exist if and only if the rays are equally spaced. We also obtain a normal family analogue of this result. MSC 2020: 30D30, 30D35, 30D45.
Size performance of the Lagrange Multiplier (LM) unit root test in the presence of a neglected break under the null

Via simulation, the size of the lagrange multiplier (LM) unit root test is examined, when there is a neglected level or trend break under the null hypothesis. It is found that unlike other more popular unit root tests in the literature, the size of the LM is not distorted/inflated. Thus, rejections of the LM tests must not be viewed as spurious with respect to this issue of neglected breaks.
Collisional parameters of planetesimal belts, precursor of debris discs, perturbed by a nearby giant planet

Planetesimal belts are invoked to explain the prolonged existence of debris disks. Important parameters to model their collisional evolution and to compute the dust production rate are the intrinsic probability of collision $P_i$ and the mean impact velocity $U_c$. If a planet orbits close to the belt, the values of both these parameters are affected by its secular perturbations yielding a strong correlation between eccentricity $e$ and pericentre longitude $\varpi$. We adopt a new algorithm to compute both $P_i$ and $U_c$ in presence of various levels of secular correlation due to different ratios between proper and forced eccentricity. We tested this algorithm in a standard case with a Jupiter--sized planet orbiting inside a putative planetesimal belt finding that it is less collisionally active compared to a self--stirred belt because of the $e - \varpi$ coupling. The eccentricity of the planet is an important parameter in determining the amount of dust production since the erosion rate is 10 times faster when the planet eccentricity increases from 0.1 to 0.6. Also the initial conditions of the belt (either warm or cold) and its average inclination strongly affects $P_i$ and $U_c$ and then its long term collisional evolution in presence of the planet. We finally apply our method to the planetesimal belts supposedly refilling the dust disks around HD 38529 and $\epsilon$ Eridani. In the most collisionally active configurations, only a small fraction of bodies smaller than 100 km are expected to be fragmented over a time--span of 4 Gyr.