Geometry description markup language for physics simulation and analysis applications

The Geometry Description Markup Language (GDML) is a specialized XML-based language designed as an application-independent persistent format for describing the geometries of detectors associated with physics measurements. It serves to implement ''geometry trees'' which correspond to the hierarchy of volumes a detector geometry can be composed of, and to allow to identify the position of individual solids, as well as to describe the materials they are made of. Being pure XML, GDML can be universally used, and in particular it can be considered as the format for interchanging geometries among different applications. In this paper we will present the current status of the development of GDML. After having discussed the contents of the latest GDML schema, which is the basic definition of the format, we will concentrate on the GDML processors. We will present the latest implementation of the GDML ''writers'' as well as ''readers'' for either Geant4 [2], [3] or ROOT [4], [10]

Four advances in carbon-carbon materials technology

Carbon-carbon composites are a specialty class of materials having many unique properties making these composites attractive for a variety of demanding engineering applications. Chief among these properties are exceptional retention of mechanical properties at temperatures as high as 4000 F, excellent creep resistance, and low density (1.6 to 1.8 g/cu cm). Although carbon-carbon composites are currently in service in a variety of applications, much development work remains to be accomplished before these materials can be considered to be fully mature, realizing their full potential. Four recent technology advances holding particular promise for overcoming current barriers to the wide-spread commercialization of carbon-carbon composites are described. These advances are: markedly improved interlaminar strengths (more than doubled) of two dimensional composites achieved by whiskerization of the fabric reinforcing plies, simultaneously improved oxidation resistance and mechanical properties achieved by the incorporation of matrix-phase oxidation inhibitors based on carborane chemistry, improved oxidation resistance achieved by compositionally graded oxidation protective coatings, and markedly reduced processing times (hours as opposed to weeks or months) accomplished through a novel process of carbon infiltration and coatings deposition based on the use of liquid-phase precursor materials

Generation of Mars Helicopter Rotor Model for Comprehensive Analyses

The present research is aimed at providing a performance model for the Mars Helicopter (MH), to understand the complexity of the flow, and identify future regions of improvement. The low density of the Martian atmosphere and the relatively small MH rotor, result in very low chord-based Reynolds number flows. The low density and Reynolds numbers reduce the lifting force and lifting efficiency, respectively. The high drag coefficients in subcritical flow, especially for thicker sections, are attributed to laminar separation from the rear of the airfoil. In the absence of test data, efforts have been made to explore these effects using prior very low Reynolds number research efforts. The rotor chord-based Reynolds number range is observed to be subcritical, which makes boundary layer transition unlikely to occur. The state of the two-dimensional rotor boundary layer in hover is approximated by calculating the instability point, laminar separation point, and the transition location to provide understanding of the flow state in the high Mach-low Reynolds number regime. The results are used to investigate the need for turbulence modeling in Computational Fluid Dynamics (CFD) calculations afterwards. The goal is to generate a performance model for the MH rotor for a free wake analysis, because the computational budget for a complete Navier-Stokes solution for a rotating body-fitted rotor is substantial. In this study, a Reynolds-Averaged Navier-Stokes (RANS) based approach is used to generate the airfoil deck using C81Gen with stitched experimental data for very high angles of attack. A full Grid Resolution Study is performed and over 4,500 cases are completed to create the full airfoil deck. The laminar separation locations are predicted within the accuracy of the approximate method when compared with the CFD calculations. The model is presented through airfoil data tables (c81 files) that are used by comprehensive rotor analysis codes such as CAMRADII, or the mid-fidelity CFD solver RotCFD. Finally, the rotor performance is compared with experimental data from the 25ft Space Simulator at the NASA Jet Propulsion Laboratory (JPL) and shows good correlation for the rotor Figure of Merit over the available thrust range

Lipid-induced changes in the secondary structure of snake venom cardiotoxins.

The secondary structures of three snake venom cardiotoxins (from Hemachatus hemachatus, Naja naja atra, and Naja naja naja), in aqueous solution and in a lipid-bound form, were investigated by Fourier-transform infrared spectroscopy. The conformation-sensitive protein infrared bands in the amide I region were analyzed using deconvolution and band-fitting procedures. The spectra of the three cardiotoxins in aqueous buffer are very similar; they indicate a high content of both antiparallel beta-sheet structure and unordered conformation. Moreover, component bands characteristic of turns can also be identified. The binding of cardiotoxins to bilayers of dimyristoylphosphatidyl-glycerol results in an increased content of a beta-structure at the expense of the nonordered conformation. It is suggested that lipid-induced conformational transitions to a beta-structure, similar to that observed with cardiotoxins, may be operative also in membrane interaction of other proteins and peptides, particularly with those which have a small tendency to form alpha-helices

Pluto: a Monte Carlo simulation tool for hadronic physics

Pluto is a Monte-Carlo event generator designed for hadronic interactions from Pion production threshold to intermediate energies of a few GeV per nucleon, as well as for studies of heavy ion reactions. The package is entirely based on ROOT, without the need of additional packages, and uses the embedded C++ interpreter of ROOT to control the event production. The generation of events based on a single reaction chain and the storage of the resulting particle objects can be done with a few lines of a ROOT-macro. However, the complete control of the package can be taken over by the steering macro and user-defined models may be added without a recompilation of the framework. Multi-reaction cocktails can be facilitated as well using either mass-dependent or user-defined static branching ratios. The included physics uses resonance production with mass-dependent Breit-Wigner sampling. The calculation of partial and total widths for resonances producing unstable particles is performed recursively in a coupled-channel approach. Here, particular attention is paid to the electromagnetic decays, motivated by the physics program of HADES. The thermal model supports 2-component thermal distributions, longitudinal broadening, radial blast, direct and elliptic flow, and impact-parameter sampled multiplicities. The interface allows angular distribution models (e.g. for the primary meson emission) to be attached by the user as well as descriptions of multi-particle correlations using decay chain templates. The exchange of mass sampling or momentum generation models is also possible. The first feature allows for consistent coupled-channel calculations, needed for a correct description of hadronic interactions. For elementary reactions, angular distribution models for selected channels are already part of the framework, based on parameterizations of existing data. This report gives an overview of the design of the package, the included models and the user interface

ELS live surgery: a developing story

Since 2015, the European Laryngological Society (ELS) has organized on a yearly basis the European Laryngological Live Surgery Broadcast. The goal of this paper is to demonstrate the increasing worldwide audience.Material and methodsThe number of individual computers logged in, number of estimated audience, and number of countries with an active audience were calculated and compared to the numbers in 2015.ResultsIn 2018, 19 live interventions were performed in three parallel sessions. The surgeons worked in 10 departments in 8 different countries. The number of individual computers logged in increased from 1000 in 2015 to 16000 in 2018. The estimated audience increased from 3000 to 32000 visitors. The number of countries with an active audience increased from 52 to 91.DiscussionThe amount of computers logged in is increasing year by year. The audience was presenting despite inconvenient broadcasting times, highlighting the educational importance. The teaching aspect remains visible on videos of this year's and previous year's interventions. They can be seen on website http://els.livesurgery.net/home.php. The organization of the European Laryngological Live Surgery Broadcast concurs to the idea that live broadcast of laryngologic surgery is feasible and attractive. Therefore, the ELS is going to continue to organize additional European Laryngological Live Surgery Broadcasts in the future

Towards the Secondary Bar: Gas Morphology and Dynamics in NGC 4303

The bulk of the molecular line emission in the double barred galaxy NGC4303 as observed in its CO(1-0) line with the OVRO mm-interferometer comes from two straight gas lanes which run north-south along the leading sides of the large-scale primary bar. Inside a radius of ~ 400 pc the molecular gas forms a spiral pattern which, for the northern arm, can be traced to the nucleus. Comparison of the OVRO and archival HST data with dynamical models of gas flow in the inner kiloparsec of single- and double-barred galaxies shows that the observed global properties of the molecular gas are in agreement with models for the gas flow in a strong, large-scale bar, and the two-arm spiral structure seen in CO in the inner kiloparsec can already be explained by a density wave initiated by the potential of that bar. Only a weak correlation between the molecular gas distribution and the extinction seen in the HST V-H map is found in the inner 400 pc of NGC4303: The innermost part of one arm of the nuclear CO spiral correlates with a weak dust filament in the color map, while the overall dust distribution follows a ring or single-arm spiral pattern well correlated with the UV continuum. This complicated nuclear geometry of the stellar and gaseous components allows for two scenarios: (A) A self-gravitating m=1 mode is present forming the spiral structure seen in the UV continuum. In this case the gas kinematics would be unaffected by the small (~ 4'') inner bar. (B) The UV continuum traces a complete ring which is heavily extincted north of the nucleus. Such a ring forms in hydrodynamic models of double bars, but the models cannot account for the UV emission observed on the leading side of the inner bar. (abridged)Comment: 47 pages, 14 figures, accepted for publication in Ap

Orbital dependent nucleonic pairing in the lightest known isotopes of tin

By studying the 109Xe-->105Te-->101Sn superallowed alpha-decay chain, we observe low-lying states in 101Sn, the one-neutron system outside doubly magic 100Sn. We find that the spins of the ground state (J = 7=2) and first excited state (J = 5=2) in 101Sn are reversed with respect to the traditional level ordering postulated for 103Sn and the heavier tin isotopes. Through simple arguments and state-of-the-art shell model calculations we explain this unexpected switch in terms of a transition from the single-particle regime to the collective mode in which orbital-dependent pairing correlations, dominate.Comment: 5 pages 3 figure