High performance astrophysics computing

The application of high end computing to astrophysical problems, mainly in the galactic environment, is under development since many years at the Dep. of Physics of Sapienza Univ. of Roma. The main scientific topic is the physics of self gravitating systems, whose specific subtopics are: i) celestial mechanics and interplanetary probe transfers in the solar system; ii) dynamics of globular clusters and of globular cluster systems in their parent galaxies; iii) nuclear clusters formation and evolution; iv) massive black hole formation and evolution; v) young star cluster early evolution. In this poster we describe the software and hardware computational resources available in our group and how we are developing both software and hardware to reach the scientific aims above itemized.Comment: 2 pages paper presented at the Conference "Advances in Computational Astrophysics: methods, tools and outcomes", to be published in the ASP Conference Series, 2012, vol. 453, R. Capuzzo-Dolcetta, M. Limongi and A. Tornambe' ed

Image-Based and Range-Based 3D Modelling of archaeological Cultural Heritage: the Telamon of the Temple of Olympian Zeus in Agrigento (ITALY)

The Temple of Olympian Zeus in Agrigento (Italy) was one of the largest temple and at the same time one of the most original of all the Greek architecture. We don\u2019t know exactly how it was because the temple is now almost completely destroyed but it is very well-known for the presence of the Telamons. The Telamons were giant statues (about 8 meters high) probably located outside the temple to fill the interval between the columns. In accordance with the theory most accredited by archaeologists the Telamons were a decorative element and also a support for the structure. However, this hypothesis has never been scientifically proven. One Telamon has been reassembled and is shown at the Archaeological Museum of Agrigento. In 2009 a group of researchers at the University of Palermo has begun a study to test the hypothesis that the Telamons support the weight of the upper part of the temple. The study consists of a 3D survey of the Telamon, to reconstruct a detailed 3D digital model, and of a structural analysis with the Finite Element Method (FEM) to test the possibility that the Telamon could to support the weight of the upper portion of the temple. In this work the authors describe the 3D survey of Telamon carry out with Range-Based Modelling (RBM) and Image-Based Modeling (IBM). The RBM was performed with a TOF laser scanner while the IBM with the ZScan system of Menci Software and Image Master of Topcon. Several tests were conducted to analyze the accuracy of the different 3D models and to evaluate the difference between laser scanning and photogrammetric data. Moreover, an appropriate data reduction to generate a 3D model suitable for FEM analysis was tested

Cyclic creep and fatigue of TD-NiCr (thoria-dispersion-strengthened nickel-chromium), TD-Ni, and NiCr sheet at 1200 C

The resistance of thin TD-NiCr sheet to cyclic deformation was compared with that of TD-Ni and a conventional nickel-chromium alloy. Strains were determined by a calibration technique which combines room-temperature strain gage and deflection measurements with high-temperature deflection measurements. Analyses of the cyclic tests using measured tensile and creep-rupture data indicated that the TD-NiCr and NiCr alloy specimens failed by a cyclic creep mechanism. The TD-Ni specimens, on the other hand, failed by a fatigue mechanism

Star cluster disruption by a supermassive black hole binary

Binary supermassive black holes (BBHs) are expected to be one of the most powerful sources of low-frequency gravitational waves (GWs) for future space-borne detectors. Prior to the GW emission stage, BBHs evolving in gas-poor nuclei shrink primarily through the slingshot ejection of stars approaching the BBH from sufficiently close distances. Here we address the possibility that the BBH shrinking rate is enhanced through the infall of a star cluster (SC) onto the BBH. We present the results of direct summation N-body simulations exploring different orbits for the SC infall, and we show that SCs reaching the BBH on non-zero angular momentum orbits (with eccentricity 0.75) fail to enhance the BBH hardening, while SCs approaching the BBH on radial orbits reduce the BBH separation by 3c 10% in less than 10 Myr, effectively shortening the BBH path towards GWs

Star cluster disruption by a massive black hole binary

Massive black hole binaries (BHBs) are expected to form as the result of galaxy mergers; they shrink via dynamical friction and stellar scatterings, until gravitational waves (GWs) bring them to the final coalescence. It has been argued that BHBs may stall at a parsec scale and never enter the GW stage if stars are not continuously supplied to the BHB loss cone. Here, we perform several N-body experiments to study the effect of an 8 7 104M 99 stellar cluster (SC) infalling on a parsec-scale BHB. We explore different orbital elements for the SC, and we perform runs both with and without accounting for the influence of a rigid stellar cusp (modelled as a rigid Dehnen potential). We find that the semimajor axis of the BHB shrinks by 73 10 per cent if the SC is on a nearly radial orbit; the shrinking is more efficient when a Dehnen potential is included and the orbital plane of the SC coincides with that of the BHB. In contrast, if the SC orbit has non-zero angular momentum, only few stars enter the BHB loss cone and the resulting BHB shrinking is negligible. Our results indicate that SC disruption might significantly contribute to the shrinking of a parsec-scale BHB only if the SC approaches the BHB on a nearly radial orbit

Adolescent and Young Adult Mental Health is Better in States that Mandate More School Mental Health Policies

Mental health problems and suicide rates have increased among adolescents and young adults over the past several years. This research brief shows that adolescent and young adult mental health is better in states that mandate more school mental health policies, including school-based mental health centers, professional development in suicide prevention, and social-emotional curricula

Solos do Assentamento Mato Grande - Corumbá, MS: caracterização, limitações e aptidão agrícola.

Argissolos; Cambissolos; Luvissolos; Neossolos; Planossolos; Vertissolos; Aptidão agrícola das terras; Inserção do agricultor no mercado.bitstream/item/37736/1/DOC27.pd

Adolescent and Young Adult Mental Health is Better in States that Mandate More School Mental Health Policies

Mental health problems and suicide rates have increased among adolescents and young adults over the past several years. This research brief shows that adolescent and young adult mental health is better in states that mandate more school mental health policies, including school-based mental health centers, professional development in suicide prevention, and social-emotional curricula