Constraints on the near-Earth asteroid obliquity distribution from the Yarkovsky effect

Aims. From lightcurve and radar data we know the spin axis of only 43 near-Earth asteroids. In this paper we attempt to constrain the spin axis obliquity distribution of near-Earth asteroids by leveraging the Yarkovsky effect and its dependence on an asteroid’s obliquity. Methods. By modeling the physical parameters driving the Yarkovsky effect, we solve an inverse problem where we test different simple parametric obliquity distributions. Each distribution results in a predicted Yarkovsky effect distribution that we compare with a X2 test to a dataset of 125 Yarkovsky estimates. Results. We find different obliquity distributions that are statistically satisfactory. In particular, among the considered models, the best-fit solution is a quadratic function, which only depends on two parameters, favors extreme obliquities, consistent with the expected outcomes from the YORP effect, has a 2:1 ratio between retrograde and direct rotators, which is in agreement with theoretical predictions, and is statistically consistent with the distribution of known spin axes of near-Earth asteroids

Tool-automation for supporting the DSL learning process

Recent technologies advances reduced significantly the effort needed to develop Domain Specific Languages (DSLs), enabling the transition to language oriented software development. In this scenario new DSLs are developed and evolve at fast-pace, to be used by a small user-base. This impose a large effort on users to learn the DSLs, while DSL designers can use little feedback to guide successive evolutions, usually just based on anecdotal considerations. We advocate that a central challenge with the proliferation of DSLs is to help users to learn the DSL and providing useful analyses to the language designers, to understand what is working and what is not in the developed DSL. In this position paper we sketch possible directions for tool-automation to support the learning processes associated with DSL adoption and to permit faster evolution cycles of the DSLs

The holonomy of IIB supercovariant connection

We show that the holonomy of the supercovariant connection of IIB supergravity is contained in SL(32, \bR). We also find that the holonomy reduces to a subgroup of SL(32-N)\st (\oplus^N \bR^{32-N}) for IIB supergravity backgrounds with $N$ Killing spinors. We give the necessary and sufficient conditions for a IIB background to admit $N$ Killing spinors. A IIB supersymmetric probe configuration can involve up to 31 linearly independent planar branes and preserves one supersymmetry.Comment: 8 pages, latex. v2: Minor correction

Test de Zohlen y su relación con el ángulo Q en población sin dolor patelofemoral

ResumenObjetivoDeterminar qué porcentaje de una población sin dolor anterior de rodilla tiene un test de Zohlen positivo, además determinar el ángulo Q de esta población y buscar si existe alguna relación entre la positividad del test de Zohlen y alteraciones en el ángulo Q.Material y métodoEstudio descriptivo-prospectivo observacional. Aplicación del test de Zohlen y medición del ángulo Q. La población se dividió en 2 grupos: test de Zohlen positivo y test de Zohlen negativo. Cuantificación y comparación de medias del ángulo Q en los dos grupos.Resultados90 sujetos evaluados, promedio de edad 20,18 años (18-40). Veinte sujetos (22,2%) con test de Zohlen positivo. Ángulo Q promedio en los sujetos con test de Zohlen negativo: 14,95°; ángulo Q promedio en los sujetos con test de Zohlen positivo: 16,9° (p < 0,05).Ángulo Q promedio en hombres con test de Zohlen negativo13,4°; ángulo Q promedio en hombres con test de Zohlen positivo: 16° (p < 0,05). Ángulo Q promedio en mujeres con test de Zohlen negativo: 16,5°; ángulo Q promedio en mujeres con test de Zohlen positivo: 18°, sin diferencias estadísticamente significativas entre ambos grupos.ConclusionesEl test de Zohlen tiene una correlación positiva con el ángulo Q en sujetos de sexo masculino. Dada la correlación entre un ángulo Q alterado y la presencia de dolor anterior de rodilla, en los pacientes que presentan un test de Zohlen positivo sin haber consultado por dolor anterior de rodilla, la prevención primaria de dolor anterior de rodilla puede ser de utilidad.AbstractObjectiveTo determine the percentage of a population without anterior knee pain with a positive Zohlen test, and also to determine the Q angle of this population and to determine if there is any relationship between the Zohlen test and Q angle anomalies.MethodsA prospective observational study was conducted in which Zohleńs test was applied and the Q angle was measured. The population was divided into 2 groups: Zohleńs positive and Zohleńs negative. Q angle was compared in the 2 groups.ResultsThe study included 90 subjects, with a mean age 20.18 years (18-40), of whom 20 subjects (22.2%) had positive Zohleńs test. The mean Q angle in subjects with negative Zohleńs test was 14.95°, and the mean Q angle in subjects with positive Zohleńs test was 16,9° (p<.05). The mean Q angle in men with negative Zohleńs test was 13.4°, and the mean Q angle in men with positive Zohleńs test was 16° (p < .05). The mean Q angle in women with negative Zohleńs test was 16.5°, with a mean Q angle of 18° in women with positive Zohleńs test, with no statistically significant differences found between groups.ConclusionsZohleńs test has a positive correlation with the Q angle in male subjects. Given the correlation between the Q angle and the presence of anterior knee pain in patients who have a positive test without symptoms, primary prevention of anterior knee pain can be achieved

On the role of AGN feedback on the thermal and chemodynamical properties of the hot intra-cluster medium

We present an analysis of the properties of the ICM in an extended set of cosmological hydrodynamical simulations of galaxy clusters and groups performed with the TreePM+SPH GADGET-3 code. Besides a set of non-radiative simulations, we carried out two sets of simulations including radiative cooling, star formation, metal enrichment and feedback from supernovae, one of which also accounts for the effect of feedback from AGN resulting from gas accretion onto super-massive black holes. These simulations are analysed with the aim of studying the relative role played by SN and AGN feedback on the general properties of the diffuse hot baryons in galaxy clusters and groups: scaling relations, temperature, entropy and pressure radial profiles, and ICM chemical enrichment. We find that simulations including AGN feedback produce scaling relations that are in good agreement with X-ray observations at all mass scales. However, our simulations are not able to account for the observed diversity between CC and NCC clusters: unlike for observations, we find that temperature and entropy profiles of relaxed and unrelaxed clusters are quite similar and resemble more the observed behaviour of NCC clusters. As for the pattern of metal enrichment, we find that an enhanced level of iron abundance is produced by AGN feedback with respect to the case of purely SN feedback. As a result, while simulations including AGN produce values of iron abundance in groups in agreement with observations, they over-enrich the ICM in massive clusters. The efficiency of AGN feedback in displacing enriched gas from halos into the inter-galactic medium at high redshift also creates a widespread enrichment in the outskirts of clusters and produces profiles of iron abundance whose slope is in better agreement with observations.Comment: 23 pages, 14 figures, 1 table, accepted for publication in MNRA

Penrose limits of Lie Branes and a Nappi--Witten braneworld

Departing from the observation that the Penrose limit of AdS_3 x S^3 is a group contraction in the sense of Inonu and Wigner, we explore the relation between the symmetric D-branes of AdS_3 x S^3 and those of its Penrose limit, a six-dimensional symmetric plane wave analogous to the four-dimensional Nappi--Witten spacetime. Both backgrounds are Lie groups admitting bi-invariant lorentzian metrics and symmetric D-branes wrap their (twisted) conjugacy classes. We determine the (twisted and untwisted) symmetric D-branes in the plane wave background and we prove the existence of a space-filling D5-brane and, separately, of a foliation by D3-branes with the geometry of the Nappi--Witten spacetime which can be understood as the Penrose limit of the AdS_2 x S^2 D3-brane in AdS_3 x S^3. Parenthetically we also derive a simple criterion for a symmetric plane wave to be isometric to a lorentzian Lie group. In particular we observe that the maximally supersymmetric plane wave in IIB string theory is isometric to a lorentzian Lie group, whereas the one in M-theory is not.Comment: 21 pages (v2: references added

Complete Characterization of Quantum-Optical Processes

The technologies of quantum information and quantum control are rapidly improving, but full exploitation of their capabilities requires complete characterization and assessment of processes that occur within quantum devices. We present a method for characterizing, with arbitrarily high accuracy, any quantum optical process. Our protocol recovers complete knowledge of the process by studying, via homodyne tomography, its effect on a set of coherent states, i.e. classical fields produced by common laser sources. We demonstrate the capability of our protocol by evaluating and experimentally verifying the effect of a test process on squeezed vacuum.Comment: 5 pages, 4 figure

Penrose limits, supergravity and brane dynamics

We investigate the Penrose limits of classical string and M-theory backgrounds. We prove that the number of (super)symmetries of a supergravity background never decreases in the limit. We classify all the possible Penrose limits of AdS x S spacetimes and of supergravity brane solutions. We also present the Penrose limits of various other solutions: intersecting branes, supersymmetric black holes and strings in diverse dimensions, and cosmological models. We explore the Penrose limit of an isometrically embedded spacetime and find a generalisation to spaces with more than one time. Finally, we show that the Penrose limit is a large tension limit for all branes including those with fields of Born--Infeld type.Comment: 67 page

Searching for keV Sterile Neutrino Dark Matter with X-ray Microcalorimeter Sounding Rockets

High-resolution X-ray spectrometers onboard suborbital sounding rockets can search for dark matter candidates that produce X-ray lines, such as decaying keV-scale sterile neutrinos. Even with exposure times and effective areas far smaller than XMM-Newton and Chandra observations, high-resolution, wide field-of-view observations with sounding rockets have competitive sensitivity to decaying sterile neutrinos. We analyze a subset of the 2011 observation by the X-ray Quantum Calorimeter instrument centered on Galactic coordinates l = 165, b = -5 with an effective exposure of 106 seconds, obtaining a limit on the sterile neutrino mixing angle of sin^2(2 theta) < 7.2e-10 at 95% CL for a 7 keV neutrino. Better sensitivity at the level of sin^2(2 theta) ~ 2.1e-11 at 95\% CL for a 7 keV neutrino is achievable with future 300-second observations of the galactic center by the Micro-X instrument, providing a definitive test of the sterile neutrino interpretation of the reported 3.56 keV excess from galaxy clusters.Comment: 13 pages, 13 figures, submitted to Ap