Cationic ordering control of magnetization in Sr2FeMoO6 double perovskite

The role of the synthesis conditions on the cationic Fe/Mo ordering in Sr2FeMoO6 double perovskite is addressed. It is shown that this ordering can be controlled and varied systematically. The Fe/Mo ordering has a profound impact on the saturation magnetization of the material. Using the appropriate synthesis protocol a record value of 3.7muB/f.u. has been obtained. Mossbauer analysis reveals the existence of two distinguishable Fe sites in agreement with the P4/mmm symmetry and a charge density at the Fe(m+) ions significantly larger than (+3) suggesting a Fe contribution to the spin-down conduction band. The implications of these findings for the synthesis of Sr2FeMoO6 having optimal magnetoresistance response are discussed.Comment: 9 pages, 4 figure

Do vegetation patch spatial patterns disrupt the spatial organization of plant species?

Thelong-range spatial autocorrelationwasevaluated based on the dispersal abilities of the species.Among the 106 species evaluated, 39%of thewoody species, 17% of the forbs, and 12% of the grasses exhibited disrupted long-range spatial autocorrelation where patches were small. The species that are more vulnerable to the effects of fragmentation tended to be those that have restricted dispersal, such as those that have short-range ispersal (atelechoric), e.g., Phlomis purpurea, Cistus albidus, Teucrium pseudochamaepytis, Brachypodium retusum, and the ballistic species, Genista spartioides. Helianthemumalmeriense is another vulnerable species that has actively restricted dispersal (antitelechory), which is common in arid regions. Wind dispersers such as Launaea lanifera were less vulnerable to the effects of fragmentation. Long-distance dispersers whose persistence depends on facilitative interactions with other individuals, e.g., allogamous species such as Thymus hyemalis, Ballota hirsuta, and Anthyllis cytisoides, exhibit disrupted long-range spatial autocorrelation when patch size is reduce

Biomarcadores del estado inflamatorio: nexo de unión con la obesidad y complicaciones asociadas

El objetivo de este trabajo ha consistido en realizar una revisión de los biomarcadores que actualmente se proponen como el nexo de unión entre la inflamación, la obesidad y complicaciones asociadas, seleccionando los estudios llevados a cabo y las cuestiones pendientes. Cada vez hay mayor evidencia científica de que la inflamación puede jugar un papel importante en la etiología de diversas enfermedades crónicas de gran relevancia para la salud pública. En los últimos años, distintos estudios han sugerido que la obesidad podría ser un desorden inflamatorio. Asimismo, el estrés oxidativo se ha propuesto como un potencial inductor de la inflamación y de la susceptibilidad a la obesidad y patología asociadas. Entre los biomarcadores relacionados con la obesidad, la resistencia insulínica, las enfermedades cardiovasculares y el síndrome metabólico se encuentran: el factor de necrosis tumoral alfa, interleuquinas 6 y 18, angiotensinógeno, factor de crecimiento TGF-beta, inhibidor de la activación del plasminógeno, leptina, resistina, proteína C reactiva, amiloide A, ácido siálico, marcadores de disfunción endotelial (factor von Willebrand, ICAMs, vCAMs) factor 3 del sistema del complemento, haptoglobina, glicoproteína zinc-alfa2, eotaxina, visfatina, apelina, alfa1-antitripsina, vaspina, omentina, proteína transportadora de retinol 4, ceruloplasmina, adiponectina y desnutrina. Algunos de estos biomarcadores son buenos predictores de riesgo cardiovascular (inhibidor de la activación de plasminógeno 1, angiotensinógeno, fibrinógeno, ácido siálico, factor 3 del complemento y proteína C reactiva), adiposidad (leptina, visfatina, resistina, haptoglobina) y/o resistencia insulínica (ácido siálico, proteína C reactiva, inhibidor de la activación de plasminógeno 1, factor von Willebrand). Sin embargo, todavía queda por dilucidar el papel de muchos de ellos en la etiología de la obesidad y comorbilidades asociadas en humanos, así como los factores implicados en su regulación

Integrable models and degenerate horizons in two-dimensional gravity

We analyse an integrable model of two-dimensional gravity which can be reduced to a pair of Liouville fields in conformal gauge. Its general solution represents a pair of ``mirror'' black holes with the same temperature. The ground state is a degenerate constant dilaton configuration similar to the Nariai solution of the Schwarzschild-de Sitter case. The existence of $\phi=const.$ solutions and their relation with the solution given by the 2D Birkhoff's theorem is then investigated in a more general context. We also point out some interesting features of the semiclassical theory of our model and the similarity with the behaviour of AdS$_2$ black holes.Comment: Latex, 16 pages, 1 figur

Aerothermodynamic Analysis of Faceted Aeroshell at Hypersonic Speed

This study explores the aerothermal behaviour of a rigid mechanically deployable aeroshell developed at Imperial College London for high payload atmospheric entry missions. The multiphysics CFD software STAR-CCM+ is used to perform a Conjugate Heat Transfer analysis on the aeroshell's faceted geometry. Results are presented for four different geometry models tested in air at Mach 5 with angles of attack 0{\deg}, 5{\deg} and 10{\deg}. The predicted surface heat transfer reveals areas of elevated heat loads at the ribs between facets and at the aeroshell shoulder, due to local boundary layer thinning. The increase in heat transfer at the ribs depends on the sharpness of the rib: more rounded shapes result in lower heat fluxes. Comparison with high-speed wind tunnel tests shows good agreement with experimental data. Stanton number and temperature profiles agree within 8% and 2%, respectively. The discrepancies between experiments and simulations are largest at the sharp ribs of the aeroshell. The sources of error can be associated with three-dimensional effects neglected in the heat flux derivations from temperature measurements as well as experimental uncertainties.Comment: Conference paper presented at HiSST: 2nd International Coneference on High-Speed Vehicle Science Technology (Bruges, Belgium 2022

The intrinsic dimensionality of spectro-polarimetric data

The amount of information available in spectro-polarimetric data is estimated. To this end, the intrinsic dimensionality of the data is inferred with the aid of a recently derived estimator based on nearest-neighbor considerations and obtained applying the principle of maximum likelihood. We show in detail that the estimator correctly captures the intrinsic dimension of artificial datasets with known dimension. The effect of noise in the estimated dimension is analyzed thoroughly and we conclude that it introduces a positive bias that needs to be accounted for. Real simultaneous spectro-polarimetric observations in the visible 630 nm and the near-infrared 1.5 microns spectral regions are also investigated in detail, showing that the near-infrared dataset provides more information of the physical conditions in the solar atmosphere than the visible dataset. Finally, we demonstrate that the amount of information present in an observed dataset is a monotonically increasing function of the number of available spectral lines.Comment: 12 pages, 7 figures, accepted for publication in the Astrophysical Journa

Halo properties and secular evolution in barred galaxies

The halo plays a crucial role in the evolution of barred galaxies. Its near-resonant material absorbs angular momentum emitted from some of the disc particles and helps the bar become stronger. As a result, a bar (oval) forms in the inner parts of the halo of strongly barred disc galaxies. It is thinner in the inner parts (but still considerably fatter than the disc bar) and tends to spherical at larger radii. Its length increases with time, while always staying shorter than the disc bar. It is roughly aligned with the disc bar, which it trails only slightly, and it turns with roughly the same pattern speed. The bi-symmetric component of the halo density continues well outside the halo bar, where it clearly trails behind the disc bar. The length and strength of the disc and halo bars correlate; the former being always much stronger than the latter. If the halo is composed of weakly interacting massive particles, then the formation of the halo bar, by redistributing the matter in the halo and changing its shape, could influence the expected annihilation signal. This is indeed found to be the case if the halo has a core, but not if it has a steep cusp. The formation and evolution of the bar strongly affect the halo orbits. A fraction of them becomes near-resonant, similar to the disc near-resonant orbits at the same resonance, while another fraction becomes chaotic. Finally, a massive and responsive halo makes it harder for a central mass concentration to destroy the disc bar.Comment: 6 pages, 3 figures, to appear in "Island Universes - Structure and Evolution of Disk Galaxies" ed. R. S. de Jon

Unconventional carrier-mediated ferromagnetism above room temperature in ion-implanted (Ga, Mn)P:C

Ion implantation of Mn ions into hole-doped GaP has been used to induce ferromagnetic behavior above room temperature for optimized Mn concentrations near 3 at.%. The magnetism is suppressed when the Mn dose is increased or decreased away from the 3 at.% value, or when n-type GaP substrates are used. At low temperatures the saturated moment is on the order of one Bohr magneton, and the spin wave stiffness inferred from the Bloch-law T^3/2 dependence of the magnetization provides an estimate Tc = 385K of the Curie temperature that exceeds the experimental value, Tc = 270K. The presence of ferromagnetic clusters and hysteresis to temperatures of at least 330K is attributed to disorder and proximity to a metal-insulating transition.Comment: 4 pages, 4 figures (RevTex4

The ISLAndS project II: The Lifetime Star Formation Histories of Six Andromeda dSphs

The Initial Star formation and Lifetimes of Andromeda Satellites (ISLAndS) project uses Hubble Space Telescope imaging to study a representative sample of six Andromeda dSph satellite companion galaxies. The main goal of the program is to determine whether the star formation histories (SFHs) of the Andromeda dSph satellites demonstrate significant statistical differences from those of the Milky Way, which may be attributable to the different properties of their local environments. Our observations reach the oldest main sequence turn-offs, allowing a time resolution at the oldest ages of ~ 1 Gyr, which is comparable to the best achievable resolution in the MW satellites. We find that the six dSphs present a variety of SFHs that are not strictly correlated with luminosity or present distance from M31. Specifically, we find a significant range in quenching times (lookback times from 9 to 6 Gyr), but with all quenching times more than ~ 6 Gyr ago. In agreement with observations of Milky Way companions of similar mass, there is no evidence of complete quenching of star formation by the cosmic UV background responsible for reionization, but the possibility of a degree of quenching at reionization cannot be ruled out. We do not find significant differences between the SFHs of the three members of the vast, thin plane of satellites and the three off-plane dSphs. The primary difference between the SFHs of the ISLAndS dSphs and Milky Way dSph companions of similar luminosities and host distances is the absence of very late quenching (< 5 Gyr ago) dSphs in the ISLAndS sample. Thus, models that can reproduce satellite populations with and without late quenching satellites will be of extreme interest.Comment: 24 pages, 11 figures, 3 tables, submitted to the Ap