Automated data collection based on RoboDiff at the ESRF beamline MASSIF-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurizzo, Didier, E-mail: Didier.nurizzo@esrf.fr; Guichard, Nicolas; McSweeney, Sean

2016-07-27

The European Synchrotron Radiation Facility has a long standing history in the automation of experiments in Macromolecular Crystallography. MASSIF-1 (Massively Automated Sample Screening and evaluation Integrated Facility), a beamline constructed as part of the ESRF Upgrade Phase I program, has been open to the external user community since July 2014 and offers a unique completely automated data collection service to both academic and industrial structural biologists.

Spaced planar laminations formed by repetitive basal erosion and resurgence to high-sedimentation-rate regime: new insight from a bedform-like structures and laterally continuous exposures

NASA Astrophysics Data System (ADS)

Ishihara, Yoshiro; Yuri, Onishi; Tsuda, Keisuke; Yokokawa, Miwa

2017-04-01

Spaced planar laminations (SPL), or so-called traction carpet deposits, are frequently observed in deposits of sediment gravity flows. Several sedimentation models for a succession of inversely graded units have been suggested from field observations and flume experiments. The formation of the inversely graded unit could be summarized as follows: (1) abrupt sedimentation on freezing of an inversely graded layer, or (2) interruptions in flow causing a freezing of an inversely graded layer at the most basal part of flow. In either case, traction carpets as a bed load overlying the erosive boundary at the base of flow are required. Although some descriptions have reported SPLs forming antidune bedform-like structures and the association of SPLs with structureless massive deposits have not been clearly explained. In this study, we suggest a novel model of SPL formation by repetition of basal erosion and resurgence to high-sedimentation rates, based on detail examinations of SPLs both showing bedform-like structures and lateral extents of hundreds of meters. SPLs were investigated in the Mio-Pliocene Kiyosumi Formation in central Japan and the Miocene Aoshima Formation in southwest Japan. In a turbidite in the Kiyosumi Formation, SPLs show three mound-like structures, suggesting antidune bedforms with wavelengths of about 6 to 7 m. On the upcurrent flanks, SPLs show lenticular cross laminations or pinching out of units; those units do not show clear inverse grading. Rip-up mud clasts and relatively high-angle imbrications are also observed. On the other hand, SPLs on the downcurrent flanks show relatively clear inverse grading and transition downcurrent into a massive structureless bed. In the Aoshima Formation, SPLs with ca. 1 cm unit thickness continue approximately 50 m along a palaeocurrent direction without changes in thickness. These SPLs gradually transition upward into a massive structureless unit. From the observations described above, in addition to descriptions from previous studies, it is suggested that SPLs comprising mound-like bedforms exhibit erosive conditions in the upcurrent flanks and depositional conditions in the downcurrent flanks, whereas SPLs on flat sea-floor extensively maintain their structure. Also, massive structureless beds are observed when erosion did not occur. These facts indicate that SPLs are strongly associated with an erosional process at the base of sediment gravity flows under a supercritical flow condition. The formation of SPLs does not necessary require a traction carpet and they may reflect basal erosion with a lag deposit of fine-grained particles, followed by resurgence to conditions of high sedimentation rates and massive structureless bed deposition. Repetitions of inversely graded units could occur when basal shear stresses are changed by fluctuations of flow depth, such as internal waves in a sediment gravity flow. This model can explain the concurrence of massive structureless beds with SPLs and examples of bedform-like structures without a unit thickness control.

Mechanism for thermal relic dark matter of strongly interacting massive particles.

PubMed

Hochberg, Yonit; Kuflik, Eric; Volansky, Tomer; Wacker, Jay G

2014-10-24

We present a new paradigm for achieving thermal relic dark matter. The mechanism arises when a nearly secluded dark sector is thermalized with the standard model after reheating. The freeze-out process is a number-changing 3→2 annihilation of strongly interacting massive particles (SIMPs) in the dark sector, and points to sub-GeV dark matter. The couplings to the visible sector, necessary for maintaining thermal equilibrium with the standard model, imply measurable signals that will allow coverage of a significant part of the parameter space with future indirect- and direct-detection experiments and via direct production of dark matter at colliders. Moreover, 3→2 annihilations typically predict sizable 2→2 self-interactions which naturally address the "core versus cusp" and "too-big-to-fail" small-scale structure formation problems.

A butterfly-shaped 'Papillon Nebula' yields secrets of massive star birth

NASA Astrophysics Data System (ADS)

1999-06-01

The newly found massive newborn stars are in one of our satellite galaxies, the Large Magellanic Cloud (LMC), 170,000 light-years away - right in our cosmic backyard. The Hubble image shows a view of a turbulent cauldron of starbirth, unromantically called N159. Fierce stellar winds from the hot newborn massive stars sculpt ridges, arcs and filaments in the vast cloud, which is over 150 light-years across. This is the clearest image ever obtained of this region. Seen for the first time is the butterfly-shaped or 'Papillon' (French for butterfly) nebula, buried in the centre of the maelstrom of glowing gases and dark dust. The unprecedented details of the structure of the Papillon, itself less than 2 light-years in size (about 1/2000th of a degree in the sky), are seen in the inset. This bipolar shape might be explained by the outflow of gas from the massive star (over 10 times the mass of our Sun) hidden in the central absorption zone. Such stars are so hot and bright that the pressure created by their light halts the infall of gas and directs it away from the star in two opposite directions. This mechanism is not fully understood, but presumably the outflow is constrained around the star's equator and directed to escape along the star's rotation axis. This observation is part of a search for young massive stars in the LMC. This butterfly-shaped nebula is considered to be a rare class of compact 'blob' around newborn, massive stars. The red in this true-colour image comes from the emission of hydrogen and the yellow from hotter oxygen gas. The picture was taken on 5 September 1998 with Wide Field Planetary Camera 2.

Mass loss and stellar superwinds

NASA Astrophysics Data System (ADS)

Vink, Jorick S.

2017-09-01

Mass loss bridges the gap between massive stars and supernovae (SNe) in two major ways: (i) theoretically, it is the amount of mass lost that determines the mass of the star prior to explosion and (ii) observations of the circumstellar material around SNe may teach us the type of progenitor that made the SN. Here, I present the latest models and observations of mass loss from massive stars, both for canonical massive O stars, as well as very massive stars that show Wolf-Rayet type features. This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'.

Magnetic structure of Basse-Terre volcanic island (Guadeloupe, Lesser Antilles) inferred from 3D inversion of aeromagnetic data

NASA Astrophysics Data System (ADS)

Barnoud, Anne; Bouligand, Claire; Coutant, Olivier; Carlut, Julie

2017-12-01

We interpret aeromagnetic data to constrain the magnetic structure of the island of Basse-Terre, Guadeloupe, Lesser Antilles. Aeromagnetic data are inverted in the spatial domain with a Bayesian formulation to retrieve the 3D distribution of rock magnetization intensity and polarity. The inversion is regularized using a correlation length and standard deviation for magnetization chosen to be consistent with results from paleomagnetic measurements on lava flow samples from Basse-Terre. The resulting 3D model of magnetization is consistent at the surface with observed polarities and at depth with a 2D model obtained from a Parker and Huestis (1974) inversion in the Fourier domain. The inferred magnetic structure is compared with the available geological information deduced from published geological, geomorphological and geochronological studies. In the southern part of the island, very low magnetization is observed around the Soufrière lava dome, last activity of the Grande-Découverte-Carmichaël-Soufrière composite volcano, in relation with a high level of hydrothermal alteration. High-magnetizations in the South-East might reflect the presence of massive lava flows and lava domes from the Madeleine vents and Monts Caraïbes. Medium magnetizations in the South-West coincide with the location of debris avalanche deposits associated with the collapse of the former Carmichaël volcano and might reflect less massive lava structure at depth. Using the volume of normal polarity in the South part of Basse-Terre recovered in our 3D model of rock magnetization, we estimate an average construction rate of ∼ 9.4 ×10-4 km3/yr during the Brunhes chron which provides new insights on the volcanic activity of La Soufrière volcano.

Eta Carinae: An Observational Testbed for 3-D Interacting Wind Modeling

NASA Technical Reports Server (NTRS)

Gull, Theodore; Madura, Tom; Groh, Jose; Corcoran, Mike; Owocki, Stan

2011-01-01

Eta Car, with its very massive interacting winds, provides shocked arc-like structures dense enough to trace in forbidden emission lines out to 0.7" (1700 AU). As the massive binary is in a very elliptical orbit (e approx. 0.9), the spatial and velocity structures of these winds change over the 5.54 year period. We can tract ionization structures by several forbidden emission lines. With the addition of radiative transfer on a time-step frame-by-frame basis, we are learning much new information on the ballistic structures, and may gain insight on how molecules and dust might form in these very massive systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendi, S.H.; Bordbar, G.H.; Panah, B. Eslam

Motivated by the recent interests in spin−2 massive gravitons, we study the structure of neutron star in the context of massive gravity. The modifications of TOV equation in the presence of massive gravity are explored in 4 and higher dimensions. Next, by considering the modern equation of state for the neutron star matter (which is extracted by the lowest order constrained variational (LOCV) method with the AV18 potential), different physical properties of the neutron star (such as Le Chatelier's principle, stability and energy conditions) are investigated. It is shown that consideration of the massive gravity has specific contributions into themore » structure of neutron star and introduces new prescriptions for the massive astrophysical objects. The mass-radius relation is examined and the effects of massive gravity on the Schwarzschild radius, average density, compactness, gravitational redshift and dynamical stability are studied. Finally, a relation between mass and radius of neutron star versus the Planck mass is extracted.« less

Petrography of the Paleogene Volcanic Rocks of the Sierra Maestra, Southeastern Cuba

NASA Astrophysics Data System (ADS)

Bemis, V. L.

2006-12-01

This study is a petrographic analysis of over 200 specimens of the Paleogene volcanic rocks of the Sierra Maestra (Southerneastern Cuba), a key structure in the framework of the northern Caribbean plate boundary evolution. The purpose of this study is to understand the eruptive processes and the depositional environments. The volcanic sequence in the lower part of the Sierra Maestra begins with highly porphyritic pillow lavas, topped by massive tuffs and autoclastic flows. The presence of broken phenocrystals, palagonitic glass and hyaloclastites in this section of the sequence suggests that the prevalent mode of eruption was explosive. The absence of welding in the tuffs suggests that the rocks were emplaced in a deep submarine environment. Coherent flows, much less common than the massive tuffs, show evidence of autoclastic fracturing, also indicating low temperature-submarine environments. These observations support the hypothesis that the Sierra Maestra sequence may be neither part of the Great Antilles Arc of the Mesozoic nor any other fully developed volcanic arc, rather a 250 km long, submarine eruptive system of dikes, flows and sills, most likely a back-arc structure. The volcanic rocks of the upper sequence are all very fine grained, reworked volcaniclastic materials, often with the structures of distal turbidities, in mode and texture similar to those drilled on the Cayman Rise. This study suggests that the Sierra Maestra most likely records volcanism of diverse sources: a local older submarine source, and one or more distal younger sources, identifiable with the pan-Caribbean volcanic events of the Tertiary.

Eta Carinae: Viewed from Multiple Vantage Points

NASA Technical Reports Server (NTRS)

Gull, Theodore

2007-01-01

The central source of Eta Carinae and its ejecta is a massive binary system buried within a massive interacting wind structure which envelops the two stars. However the hot, less massive companion blows a small cavity in the very massive primary wind, plus ionizes a portion of the massive wind just beyond the wind-wind boundary. We gain insight on this complex structure by examining the spatially-resolved Space Telescope Imaging Spectrograph (STIS) spectra of the central source (0.1") with the wind structure which extends out to nearly an arcsecond (2300AU) and the wind-blown boundaries, plus the ejecta of the Little Homunculus. Moreover, the spatially resolved Very Large Telescope/UltraViolet Echelle Spectrograph (VLT/UVES) stellar spectrum (one arcsecond) and spatially sampled spectra across the foreground lobe of the Homunculus provide us vantage points from different angles relative to line of sight. Examples of wind line profiles of Fe II, and the.highly excited [Fe III], [Ne III], [Ar III] and [S III)], plus other lines will be presented.

Mass loss and stellar superwinds.

PubMed

Vink, Jorick S

2017-10-28

Mass loss bridges the gap between massive stars and supernovae (SNe) in two major ways: (i) theoretically, it is the amount of mass lost that determines the mass of the star prior to explosion and (ii) observations of the circumstellar material around SNe may teach us the type of progenitor that made the SN. Here, I present the latest models and observations of mass loss from massive stars, both for canonical massive O stars, as well as very massive stars that show Wolf-Rayet type features.This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'. © 2017 The Author(s).

Topics in Higher-Derivative Supergravity and N = 2 Yang-Mills Theories

NASA Astrophysics Data System (ADS)

Hindawi, Ahmed Abdel-Ati

1997-09-01

In Part I of the thesis we discuss higher-derivative theories of gravity. We start by discussing the field content of quadratic higher-derivative gravity, together with a new example of a massless spin-two field consistently coupled to gravity. The full quadratic gravity theory is shown to be equivalent to a canonical second-order theory of a massive scalar field, a massive spin-two symmetric tensor field and gravity. It is shown that flat-space is the only stable vacuum, and that the spin-two field around it is always ghost-like. We give a procedure for exhibiting the new propagating degrees of freedom in a generic higher-derivative gravity, at the full non-linear level. We show that around any vacuum the elementary excitations remain the massless graviton, a massive scalar field and a massive ghost-like spin-two field. In Part II of the thesis we extend our investigations to the realm of supergravity. We consider the general form of quadratic (1, 1) supergravity in two dimensions. It is demonstrated that the theory possesses stable vacua with vanishing cosmological constant which spontaneously break supersymmetry. We then consider higher-derivative N=1 supergravity in four dimensions. We construct two classes of higher-derivative supergravity theories. They are found to be equivalent to Einstein supergravity coupled to one or two chiral superfields and have a rich vacuum structure. It is demonstrated that theories of the second class can possess a stable vacuum with vanishing cosmological constant that spontaneously breaks supersymmetry. We then proceed to show how spontaneous supersymmetry breaking in the vacuum state of higher-derivative supergravity is transmitted, as explicit soft supersymmetry-breaking terms, to the effective Lagrangian of the standard electroweak model. In Part III we use central charge superspace to give a geometrical construction of the N=2 Abelian vector-tensor multiplet consisting, under N=1 supersymmetry, of one vector and one linear multiplet. We derive the component field supersymmetry and central charge transformations, and show that there is a super-Lagrangian, the higher components of which are all total derivatives, allowing us to construct superfield and component actions.

Discovery of a Large-Scale Filament Connected to the Massive Galaxy Cluster MACS J0717.5+3745 at z=0.551,

NASA Astrophysics Data System (ADS)

Ebeling, H.; Barrett, E.; Donovan, D.

2004-07-01

We report the detection of a 4 h-170 Mpc long large-scale filament leading into the massive galaxy cluster MACS J0717.5+3745. The extent of this object well beyond the cluster's nominal virial radius (~2.3 Mpc) rules out prior interaction between its constituent galaxies and the cluster and makes it a prime candidate for a genuine filament as opposed to a merger remnant or a double cluster. The structure was discovered as a pronounced overdensity of galaxies selected to have V-R colors close to the cluster red sequence. Extensive spectroscopic follow-up of over 300 of these galaxies in a region covering the filament and the cluster confirms that the entire structure is located at the cluster redshift of z=0.545. Featuring galaxy surface densities of typically 15 Mpc-2 down to luminosities of 0.13L*V, the most diffuse parts of the filament are comparable in density to the clumps of red galaxies found around A851 in the only similar study carried out to date (Kodama et al.). Our direct detection of an extended large-scale filament funneling matter onto a massive distant cluster provides a superb target for in-depth studies of the evolution of galaxies in environments of greatly varying density and supports the predictions from theoretical models and numerical simulations of structure formation in a hierarchical picture. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support of the W. M. Keck Foundation. Based partly on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (US), the Particle Physics and Astronomy Research Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNP (Brazil), and CONICET (Argentina).

The EMCC / DARPA Massively Parallel Electromagnetic Scattering Project

NASA Technical Reports Server (NTRS)

Woo, Alex C.; Hill, Kueichien C.

1996-01-01

The Electromagnetic Code Consortium (EMCC) was sponsored by the Advanced Research Program Agency (ARPA) to demonstrate the effectiveness of massively parallel computing in large scale radar signature predictions. The EMCC/ARPA project consisted of three parts.

Gauge symmetry and constraints structure for topologically massive AdS gravity: a symplectic viewpoint

NASA Astrophysics Data System (ADS)

Rodríguez-Tzompantzi, Omar; Escalante, Alberto

2018-05-01

By applying the Faddeev-Jackiw symplectic approach we systematically show that both the local gauge symmetry and the constraint structure of topologically massive gravity with a cosmological constant Λ , elegantly encoded in the zero-modes of the symplectic matrix, can be identified. Thereafter, via a suitable partial gauge-fixing procedure, the time gauge, we calculate the quantization bracket structure (generalized Faddeev-Jackiw brackets) for the dynamic variables and confirm that the number of physical degrees of freedom is one. This approach provides an alternative to explore the dynamical content of massive gravity models.

Subsonic structure and optically thick winds from Wolf-Rayet stars

NASA Astrophysics Data System (ADS)

Grassitelli, L.; Langer, N.; Grin, N. J.; Mackey, J.; Bestenlehner, J. M.; Gräfener, G.

2018-06-01

Mass loss by stellar wind is a key agent in the evolution and spectroscopic appearance of massive main sequence and post-main sequence stars. In Wolf-Rayet stars the winds can be so dense and so optically thick that the photosphere appears in the highly supersonic part of the outflow, veiling the underlying subsonic part of the star, and leaving the initial acceleration of the wind inaccessible to observations. Here we investigate the conditions and the structure of the subsonic part of the outflow of Galactic Wolf-Rayet stars, in particular of the WNE subclass; our focus is on the conditions at the sonic point of their winds. We compute 1D hydrodynamic stellar structure models for massive helium stars adopting outer boundaries at the sonic point. We find that the outflows of our models are accelerated to supersonic velocities by the radiative force from opacity bumps either at temperatures of the order of 200 kK by the iron opacity bump or of the order of 50 kK by the helium-II opacity bump. For a given mass-loss rate, the diffusion approximation for radiative energy transport allows us to define the temperature gradient based purely on the local thermodynamic conditions. For a given mass-loss rate, this implies that the conditions in the subsonic part of the outflow are independent from the detailed physical conditions in the supersonic part. Stellar atmosphere calculations can therefore adopt our hydrodynamic models as ab initio input for the subsonic structure. The close proximity to the Eddington limit at the sonic point allows us to construct a sonic HR diagram, relating the sonic point temperature to the luminosity-to-mass ratio and the stellar mass-loss rate, thereby constraining the sonic point conditions, the subsonic structure, and the stellar wind mass-loss rates of WNE stars from observations. The minimum stellar wind mass-loss rate necessary to have the flow accelerated to supersonic velocities by the iron opacity bump is derived. A comparison of the observed parameters of Galactic WNE stars to this minimum mass-loss rate indicates that these stars have their winds launched to supersonic velocities by the radiation pressure arising from the iron opacity bump. Conversely, stellar models which do not show transonic flows from the iron opacity bump form low-density extended envelopes. We derive an analytic criterion for the appearance of envelope inflation and of a density inversion in the outer sub-photospheric layers.

The nummulithoclast event within the Lower Eocene in the Southern Tethyan margin: Mechanisms involved, analogy with the filament event and climate implication (Kairouan, Central Tunisia)

NASA Astrophysics Data System (ADS)

Mardassi, Besma

2017-10-01

Early Eocene deposits in Tunisia are marked by clear variations in terms of facies and thickness. Each facies corresponds to an appropriate depositional environment. Shallow water deposits pass gradually offshore into deeper carbonates along a homoclinal ramp. In Central Tunisia, detailed investigation of carbonate facies under transmitted light shows a particular richness of the middle part of Early Eocene deposits in nummulithoclasts. These facies are often frequent within corrugated banks. They are overlaying Globigerina rich well-bedded limestones and overlain by nummulites and Discocyclina rich massively-bedded carbonates. Nummulithoclasts occurrence is recorded on field by an abrupt vertical change from autochthonous thinly-bedded limestones to massively-bedded fossiliferous carbonates. Change concerns structures, textures and limestones' composition. Nummulithoclasts are associated either to planktonic micro-organisms or to benthic fauna and phosphates grains. The middle and the upper parts of the Early Eocene deposits, particularly, fossilize hummocky cross-stratifications and megaripples. Their presence advocates the role of energetic currents in sweeping nummulites from lower circatidal to upper bathyal environments. The absence of a slope break helped the settling of reworked nummulites within deeper environments. The abrupt change, nummulithoclast associations and current structures arouse reflection and make them not reliable to characterize depositional environments. However, their preferential occurrence within the middle part of Early Eocene deposits and the tight linkage with storm activity lead them to be considered as event. The large scale hummocks recorded on field suggests that nummulite fragmentation was triggered by tropical cyclones rather than humble storms. The frequent occurrence of cyclones which correspond to low pressure atmospheric systems seems in relation with a global warming enhancing the sea surface temperature.

Spatially Extended Relativistic Particles Out of Traveling Front Solutions of Sine-Gordon Equation in (1+2) Dimensions

PubMed Central

Zarmi, Yair

2016-01-01

Slower-than-light multi-front solutions of the Sine-Gordon in (1+2) dimensions, constructed through the Hirota algorithm, are mapped onto spatially localized structures, which emulate free, spatially extended, massive relativistic particles. A localized structure is an image of the junctions at which the fronts intersect. It propagates together with the multi-front solution at the velocity of the latter. The profile of the localized structure obeys the linear wave equation in (1+2) dimensions, to which a term that represents interaction with a slower-than-light, Sine-Gordon-multi-front solution has been added. This result can be also formulated in terms of a (1+2)-dimensional Lagrangian system, in which the Sine-Gordon and wave equations are coupled. Expanding the Euler-Lagrange equations in powers of the coupling constant, the zero-order part of the solution reproduces the (1+2)-dimensional Sine-Gordon fronts. The first-order part is the spatially localized structure. PACS: 02.30.Ik, 03.65.Pm, 05.45.Yv, 02.30.Ik. PMID:26930077

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vieira, H.S., E-mail: horacio.santana.vieira@hotmail.com; Bezerra, V.B., E-mail: valdir@fisica.ufpb.br; Muniz, C.R., E-mail: celiomuniz@yahoo.com

This work considers the influence of the gravitational field produced by a charged and rotating black hole (Kerr–Newman spacetime) on a charged massive scalar field. We obtain exact solutions of both angular and radial parts of the Klein–Gordon equation in this spacetime, which are given in terms of the confluent Heun functions. From the radial solution, we obtain the exact wave solutions near the exterior horizon of the black hole, and discuss the Hawking radiation of charged massive scalar particles. - Highlights: • The covariant Klein–Gordon equation for a charged massive scalar field in the Kerr–Newman black hole is solved.more » • Both angular and radial parts are transformed to a Heun-type equation. • The resulting Hawking radiation spectrum of scalar particles has a thermal character.« less

FWT2D: A massively parallel program for frequency-domain full-waveform tomography of wide-aperture seismic data—Part 1: Algorithm

NASA Astrophysics Data System (ADS)

Sourbier, Florent; Operto, Stéphane; Virieux, Jean; Amestoy, Patrick; L'Excellent, Jean-Yves

2009-03-01

This is the first paper in a two-part series that describes a massively parallel code that performs 2D frequency-domain full-waveform inversion of wide-aperture seismic data for imaging complex structures. Full-waveform inversion methods, namely quantitative seismic imaging methods based on the resolution of the full wave equation, are computationally expensive. Therefore, designing efficient algorithms which take advantage of parallel computing facilities is critical for the appraisal of these approaches when applied to representative case studies and for further improvements. Full-waveform modelling requires the resolution of a large sparse system of linear equations which is performed with the massively parallel direct solver MUMPS for efficient multiple-shot simulations. Efficiency of the multiple-shot solution phase (forward/backward substitutions) is improved by using the BLAS3 library. The inverse problem relies on a classic local optimization approach implemented with a gradient method. The direct solver returns the multiple-shot wavefield solutions distributed over the processors according to a domain decomposition driven by the distribution of the LU factors. The domain decomposition of the wavefield solutions is used to compute in parallel the gradient of the objective function and the diagonal Hessian, this latter providing a suitable scaling of the gradient. The algorithm allows one to test different strategies for multiscale frequency inversion ranging from successive mono-frequency inversion to simultaneous multifrequency inversion. These different inversion strategies will be illustrated in the following companion paper. The parallel efficiency and the scalability of the code will also be quantified.

Massive Binaries in the R 136 Cluster

NASA Astrophysics Data System (ADS)

Morrell, N. I.; Massey, P.; Degioia-Eastwood, K.; Penny, L. R.; Gies, D. R.; Tsitkin, Y.; Darnell, E.

2008-08-01

As part of a large project aimed to the discovery and follow up of massive eclipsing systems in young clusters and stellar associations, we have obtained V-band CCD imaging of the R136 cluster in 30 Doradus, and high resolution spectroscopy of several among the variable stars we found there. Here we summarize our preliminary analysis of light and radial velocity variations for 4 massive multiple systems in the R136 cluster.

Massive Structures of Galaxies at High Redshifts in the Great Observatories Origins Deep Survey Fields

NASA Astrophysics Data System (ADS)

Kang, Eugene; Im, Myungshin

2015-02-01

If the Universe is dominated by cold dark matter and dark energy as in the currently popular ΛCDM cosmology, it is expected that large scale structures form gradually, with galaxy clusters of mass M & 1014M? appearing at around 6 Gy rs after the Big Bang (z ? 1). Here, we report the discovery of 59 massive structures of galaxies with masses greater than a few times 1013M? at redshifts between z = 0.6 and 4.5 in the Great Observatories Origins Deep Survey fields. The massive structures are identified by running top-hat filters on the two dimensional spatial distribution of magnitude-limited samples of galaxies using a combination of spectroscopic and photometric redshifts. We analyze the Millennium simulation data in a similar way to the analysis of the observational data in order to test the ΛCDM cosmology. We find that there are too many massive structures (M > 7?1013M?) observed at z > 2 in comparison with the simulation predictions by a factor of a few, giving a probability of < 1/2500 of the observed data being consistent with the simulation. Our result suggests that massive structures have emerged early, but the reason for the discrepancy with the simulation is unclear. It could be due to the limitation of the simulation such as the lack of key, unrecognized ingredients (strong non-Gaussianity or other baryonic physics), or simply a difficulty in the halo mass estimation from observation, or a fundamental problem of the ΛCDM cosmology. On the other hand, the over-abundance of massive structures at high redshifts does not favor heavy neutrino mass of ? 0.3 eV or larger, as heavy neutrinos make the discrepancy between the observation and the simulation more pronounced by a factor of 3 or more.

Presupernova Evolution of Differentially Rotating Massive Stars Including Magnetic Fields

NASA Astrophysics Data System (ADS)

Heger, A.; Woosley, S. E.; Spruit, H. C.

2005-06-01

As a massive star evolves through multiple stages of nuclear burning on its way to becoming a supernova, a complex, differentially rotating structure is set up. Angular momentum is transported by a variety of classic instabilities and also by magnetic torques from fields generated by the differential rotation. We present the first stellar evolution calculations to follow the evolution of rotating massive stars including, at least approximately, all these effects, magnetic and nonmagnetic, from the zero-age main sequence until the onset of iron-core collapse. The evolution and action of the magnetic fields is as described by Spruit in 2002, and a range of uncertain parameters is explored. In general, we find that magnetic torques decrease the final rotation rate of the collapsing iron core by about a factor of 30-50 when compared with the nonmagnetic counterparts. Angular momentum in that part of the presupernova star destined to become a neutron star is an increasing function of main-sequence mass. That is, pulsars derived from more massive stars rotate faster and rotation plays a more important role in the star's explosion. The final angular momentum of the core has been determined-to within a factor of 2-by the time the star ignites carbon burning. For the lighter stars studied, around 15 Msolar, we predict pulsar periods at birth near 15 ms, though a factor of 2 range is easily tolerated by the uncertainties. Several mechanisms for additional braking in a young neutron star, especially by fallback, are explored.

Wind-US Flow Calculations for the M2129 S-Duct Using Structured and Unstructured Grids

NASA Technical Reports Server (NTRS)

Mohler, Stanley R., Jr.

2003-01-01

Computational Fluid Dynamics (CFD) flow solutions for the M2129 diffusing S-duct with and without vane effectors were computed by the Wind-US flow solver. Both structured and unstructured 3-D grids were used. Without vane effectors, the duct exhibited massive flow separation in both experiment and CFD. With vane effectors installed, the flow remained attached and aerodynamic losses were reduced. Total pressure recovery and distortion near the duct outlet were computed from the solutions and compared favorably to experimental values. These calculations are part of a validation effort for the Wind-US code. They also provide an example case to aid engineers in learning to use the Wind-US software.

Wide-Field Infrared Survey Explorer Observations of the Evolution of Massive Star-Forming Regions

NASA Technical Reports Server (NTRS)

Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Rebull, L. M.; Padgett, D. L.; Assef, R. J.

2011-01-01

We present the results of a mid-infrared survey of 11 outer Galaxy massive star-forming regions and 3 open clusters with data from the Wide-field Infrared Survey Explorer (WISE). Using a newly developed photometric scheme to identify young stellar objects and exclude extragalactic contamination, we have studied the distribution of young stars within each region. These data tend to support the hypothesis that latter generations may be triggered by the interaction of winds and radiation from the first burst of massive star formation with the molecular cloud material leftover from that earlier generation of stars.We dub this process the "fireworks hypothesis" since star formation by this mechanism would proceed rapidly and resemble a burst of fireworks.We have also analyzed small cutout WISE images of the structures around the edges of these massive star-forming regions. We observe large (1-3 pc size) pillar and trunk-like structures of diffuse emission nebulosity tracing excited polycyclic aromatic hydrocarbon molecules and small dust grains at the perimeter of the massive star-forming regions. These structures contain small clusters of emerging Class I and Class II sources, but some are forming only a single to a few new stars.

Wide-Field Infrared Survey Explorer Observations of the Evolution of Massive Star-Forming Regions

NASA Technical Reports Server (NTRS)

Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Rebull, L. M.; Padgett, D. L.; Asslef, R. J.

2012-01-01

We present the results of a mid-infrared survey of II outer Galaxy massive star-forming regions and 3 open clusters with data from the Wide-field Infrared Survey Explorer (WISE). Using a newly developed photometric scheme to identify young stellar objects and exclude extragalactic contamination, we have studied the distribution of young stars within each region. These data tend to support the hypothesis that latter generations may be triggered by the interaction of winds and radiation from the first burst of massive star formation with the molecular cloud material leftover from that earlier generation of stars. We dub this process the "fireworks hypothesis" since star formation by this mechanism would proceed rapidly and resemble a burst of fireworks. We have also analyzed small cutout WISE images of the structures around the edges of these massive star-forming regions. We observe large (1-3 pc size) pillar and trunk-like structures of diffuse emission nebulosity tracing excited polycyclic aromatic hydrocarbon molecules and small dust grains at the perimeter of the massive star-forming regions. These structures contain small clusters of emerging Class I and Class II sources, but some are forming only a single to a few new stars.

ATLASGAL - towards a complete sample of massive star forming clumps

NASA Astrophysics Data System (ADS)

Urquhart, J. S.; Moore, T. J. T.; Csengeri, T.; Wyrowski, F.; Schuller, F.; Hoare, M. G.; Lumsden, S. L.; Mottram, J. C.; Thompson, M. A.; Menten, K. M.; Walmsley, C. M.; Bronfman, L.; Pfalzner, S.; König, C.; Wienen, M.

2014-09-01

By matching infrared-selected, massive young stellar objects (MYSOs) and compact H II regions in the Red MSX Source survey to massive clumps found in the submillimetre ATLASGAL (APEX Telescope Large Area Survey of the Galaxy) survey, we have identified ˜1000 embedded young massive stars between 280° < ℓ < 350° and 10° < ℓ < 60° with | b | < 1.5°. Combined with an existing sample of radio-selected methanol masers and compact H II regions, the result is a catalogue of ˜1700 massive stars embedded within ˜1300 clumps located across the inner Galaxy, containing three observationally distinct subsamples, methanol-maser, MYSO and H II-region associations, covering the most important tracers of massive star formation, thought to represent key stages of evolution. We find that massive star formation is strongly correlated with the regions of highest column density in spherical, centrally condensed clumps. We find no significant differences between the three samples in clump structure or the relative location of the embedded stars, which suggests that the structure of a clump is set before the onset of star formation, and changes little as the embedded object evolves towards the main sequence. There is a strong linear correlation between clump mass and bolometric luminosity, with the most massive stars forming in the most massive clumps. We find that the MYSO and H II-region subsamples are likely to cover a similar range of evolutionary stages and that the majority are near the end of their main accretion phase. We find few infrared-bright MYSOs associated with the most massive clumps, probably due to very short pre-main-sequence lifetimes in the most luminous sources.

Seafloor massive sulfide deposits support unique megafaunal assemblages: Implications for seabed mining and conservation.

PubMed

Boschen, Rachel E; Rowden, Ashley A; Clark, Malcolm R; Pallentin, Arne; Gardner, Jonathan P A

2016-04-01

Mining of seafloor massive sulfides (SMS) is imminent, but the ecology of assemblages at SMS deposits is poorly known. Proposed conservation strategies include protected areas to preserve biodiversity at risk from mining impacts. Determining site suitability requires biological characterisation of the mine site and protected area(s). Video survey of a proposed mine site and protected area off New Zealand revealed unique megafaunal assemblages at the mine site. Significant relationships were identified between assemblage structure and environmental conditions, including hydrothermal features. Unique assemblages occurred at both active and inactive chimneys and are particularly at risk from mining-related impacts. The occurrence of unique assemblages at the mine site suggests that the proposed protected area is insufficient alone and should instead form part of a network. These results provide support for including hydrothermally active and inactive features within networks of protected areas and emphasise the need for quantitative survey data of proposed sites. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Old Galaxies in the Young Universe

NASA Astrophysics Data System (ADS)

2004-07-01

Very Large Telescope Unravels New Population of Very Old Massive Galaxies [1] Summary Current theories of the formation of galaxies are based on the hierarchical merging of smaller entities into larger and larger structures, starting from about the size of a stellar globular cluster and ending with clusters of galaxies. According to this scenario, it is assumed that no massive galaxies existed in the young universe. However, this view may now have to be revised. Using the multi-mode FORS2 instrument on the Very Large Telescope at Paranal, a team of Italian astronomers [2] have identified four remote galaxies, several times more massive than the Milky Way galaxy, or as massive as the heaviest galaxies in the present-day universe. Those galaxies must have formed when the Universe was only about 2,000 million years old, that is some 12,000 million years ago. The newly discovered objects may be members of a population of old massive galaxies undetected until now. The existence of such systems shows that the build-up of massive elliptical galaxies was much faster in the early Universe than expected from current theory. PR Photo 21a/04: Small Part of the K20 Field Showing the z=1.9 Elliptical Galaxy (ACS/HST). PR Photo 21b/04: Averaged Spectrum of Old Galaxies (FORS2/VLT). Hierarchical merging Galaxies are like islands in the Universe, made of stars as well as dust and gas clouds. They come in different sizes and shapes. Astronomers generally distinguish between spiral galaxies - like our own Milky Way, NGC 1232 or the famous Andromeda galaxy - and elliptical galaxies, the latter mostly containing old stars and having very little dust or gas. Some galaxies are intermediate between spirals and ellipticals and are referred to as lenticular or spheroidal galaxies. Galaxies are not only distinct in shape, they also vary in size: some may be as "light" as a stellar globular cluster in our Milky Way (i.e. they contain about the equivalent of a few million Suns) while others may be more massive than a million million Suns. Presently, more than half of the stars in the Universe are located in massive spheroidal galaxies. One of the main open questions of modern astrophysics and cosmology is how and when galaxies formed and evolved starting from the primordial gas that filled the early Universe. In the most popular current theory, galaxies in the local Universe are the result of a relatively slow process where small and less massive galaxies merge to gradually build up bigger and more massive galaxies. In this scenario, dubbed "hierarchical merging", the young Universe was populated by small galaxies with little mass, whereas the present Universe contains large, old and massive galaxies - the very last to form in the final stage of a slow assembling process. If this scenario were true, then one should not be able to find massive elliptical galaxies in the young universe. Or, in other words, due to the finite speed of light, there should be no such massive galaxies very far from us. And indeed, until now no old elliptical galaxy was known beyond a radio-galaxy at redshift 1.55 [3] that was discovered almost ten years ago. The K20 survey ESO PR Photo 21a/04 ESO PR Photo 21a/04 Part of the K20 Field, centred on the z=1.9 galaxy (ACS/HST) [Preview - JPEG: 400 x 424 pix - 45k] [Normal - JPEG: 800 x 847 pix - 712k] [Hires - JPEG: 1334 x 1413 pix - 1.3M] Caption: ESO PR Photo 21a/04 shows a small region in the K20 field surveyed by the astronomers. This region is centred on the newly discovered z=1.9 redshift galaxy. The image is based on frames acquired by the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope in the framework of the GOODS Public HST Treasury Program (P.I. M. Giavalisco, STScI, Baltimore, USA). They show the real colours of the galaxies. The four old massive spheroidal galaxies discovered in this survey appear very red compared to the other faint galaxies. (Image courtesy of Piero Rosati and Bob Fosbury, ESO Garching). In order to better understand the formation process of galaxies and to verify if the hierarchical merging scenario is valid, a team of Italian and ESO astronomers [2] used ESO's Very Large Telescope as a "time machine" to do a search for very remote elliptical galaxies. However, this is not trivial. Distant elliptical galaxies, with their content of old and red stars, must be very faint objects indeed at optical wavelengths as the bulk of their light is redshifted into the infrared part of the spectrum. Remote elliptical galaxies are thus among the most difficult observational targets even for the largest telescopes; this is also why the 1.55 redshift record has persisted for so long. But this challenge did not stop the researchers. They obtained deep optical spectroscopy with the multi-mode FORS2 instrument on the VLT for a sample of 546 faint objects found in a sky area of 52 arcmin2 (or about one tenth of the area of the Full Moon) known as the K20 field, and which partly overlaps with the GOODS-South area. Their perseverance paid off and they were rewarded by the discovery of four old, massive galaxies with redshifts between 1.6 and 1.9. These galaxies are seen when the Universe was only about 25% of its present age of 13,700 million years. For one of the galaxies, the K20 team benefited also from the database of publicly available spectra in the GOODS-South area taken by the ESO/GOODS team. A new population of galaxies ESO PR Photo 21b/04 ESO PR Photo 21b/04 Averaged Spectrum of Old Galaxies (FORS2/VLT). [Preview - JPEG: 400 x 496 pix - 58k] [Normal - JPEG: 800 x 992 pix - 366k] [Hires - JPEG: 1700 x 2108 pix - 928k] Caption: ESO PR Photo 21b/04 shows the averaged spectrum (blue) of the four newly discovered old massive galaxies compared to a set of template spectra. The bottom compares it with the spectrum of a star having a surface temperature of 7200 degrees (green) and 6800 degrees (red), respectively. The upper graph makes a comparison with synthetic spectra of simulated simple stellar populations with ages of 500, 1100 and 3000 million years. This figure demonstrates that the newly found galaxies mostly contain old low-mass stars and must have formed between 1,000 and 2,000 million years earlier than the epoch at which they are now seen. The newly discovered galaxies are thus seen when the Universe was about 3,500 million years old, i.e. 10,000 million years ago. But from the spectra taken, it appears that these galaxies contain stars with ages between 1,000 and 2,000 million years. This implies that the galaxies must have formed accordingly earlier, and that they must have essentially completed their assembly at a moment when the Universe was only 1,500 to 2,500 million years old. The galaxies appear to have masses in excess of one hundred thousand million solar masses and they are therefore of sizes similar to the most massive galaxies in the present-day Universe. Complementary images taken within the GOODS ("The Great Observatories Origins Deep Survey") survey by the Hubble Space Telescope show that these galaxies have structures and shapes more or less identical to those of the present-day massive elliptical galaxies. The new observations have therefore revealed a new population of very old and massive galaxies. The existence of such massive and old spheroidal galaxies in the early Universe shows that the assembly of the present-day massive elliptical galaxies started much earlier and was much faster than predicted by the hierarchical merging theory. Says Andrea Cimatti (INAF, Firenze, Italy), leader of the team: "Our new study now raises fundamental questions about our understanding and knowledge of the processes that regulated the genesis and the evolutionary history of the Universe and its structures."

The Formation Of Bulges, Discs And Two Component Galaxies In The CANDELS Survey At z<3

NASA Astrophysics Data System (ADS)

Margaleff Bentabol, Berta; Conselice, Christopher; CANDELS Team

2016-09-01

The most massive galaxies in the local Universe can be classified as disk-dominated and spheroid-dominated (i.e. Hubble type). However, it is unclear how and when these dominant structures form and the possible connection between them. To address this issue we have investigated massive galaxies (logM>10) in the CANDELS fields at the epoch of 1

The volcanic-sedimentary sequence of the Lousal deposit, Iberian Pyrite Belt (Portugal)

NASA Astrophysics Data System (ADS)

Rosa, Carlos; Rosa, Diogo; Matos, Joao; Relvas, Jorge

2010-05-01

The Iberian Pyrite Belt (IPB) is a massive sulfide province that is located in the south of Portugal and Spain, and hosts more than 90 massive sulfide deposits that amount to more than 1850 million metric tonnes of sulfide ore (Tornos, 2006). The ore deposits size, vary from ~1Mt to >100Mt (e.g. Neves Corvo and Aljustrel in Portugal, and Rio Tinto and Tharsis in Spain). The ore deposits are hosted by a submarine sedimentary and volcanic, felsic dominated, succession that constitutes the Upper Devonian to Lower Carboniferous Volcanic and Sedimentary Complex (VSC). The VSC ranges in thickness from approximately 600 to 1300 m (Tornos 2006). The VSC overlies the Phyllite-Quartzite Group (PQ) (Upper Devonian, base unknown) and is overlain by the Baixo Alentejo Flysch Group (Lower to Upper Carboniferous). The Lousal massive sulfide deposit is located in the western part of the IPB and occurs mostly interbedded with black mudstone. The VSC sequence at Lousal mine consists of a mudstone and quartzite sequence (PQ Group) in the lower part of the succession, over which a thick sequence of rhyolitic lavas (>300 m) occurs. Above the rhyolitic lavas there is a thick sequence of black and grey mudstone that hosts the massive sulfide ore bodies, and a rhyolitic sill. The upper part of the VSC sequence consists of a thick mudstone interval that hosts two thick basaltic units, locally with pillows. The rhyolites have small coherent cores, locally with flow bands, that grade to surrounding massive clastic intervals, with large lateral extent. The clasts show jigsaw-fit arrangement in many places and have planar or curviplanar margins and locally are perlitic at the margin. The top contact of these units is in most locations not exposed, which makes difficult to interpret the mode of emplacement. However, the thick clastic intervals, above described, are in accordance with quenching of volcanic glass with abundant water and therefore indicate that quenching of the rhyolites was the dominant fragmentation mechanism. Unlike many locations of the IPB, fiamme-rich pyroclastic units were not identified at Lousal. The ore deposits occur in close proximity with this volcanic centre that may have driven hydrothermal circulation that led to ore formation. The volcanic rocks show intense chloritic alteration, indicating that the mineralizing event occurred after most of the rhyolitic units have emplaced. The massive sulfides show abundant sedimentary structures which is not typical in the massive sulfide deposits of the IPB. The Lousal 50 Mt massive sulfide deposit consists of at least 11 ore bodies and was exploited until 1988 mainly for pyrite. The ores mined averaged 0.7% Cu, 0.8%Pb e 1.4%Zn (Strauss, 1971). These relatively low base metal grades led to an evaluation of the contents and distribution of high-tech element in the ore bodies, which would improve the economic viability of mining the deposit. This evaluation is currently focusing on the distribution and mineralogy of selenium, as ores mined in the past were known to be rich in this element. This work benefits from research projects INCA (PTDC/CTE-GIN/67027/2006; Characterization of crucial mineral resources for the development of renewable energy technologies: The Iberian Pyrite Belt ores as a source of indium and other high-technology elements) and project ARCHYMEDES II (POCTI/CTA/45873/2002), both funded by the Fundação para a Ciência e Tecnologia. REFERENCES Strauss, G.K., 1970. Sobre la geologia de la provincia piritifera del Suroeste de la Peninsula Iberica y sus yacimientos, en especial sobre la mina de pirita de Lousal (Portugal): Memoria del IGME 77, 1-266. Tornos, F., 2006. Environment of formation and styles of volcanogenic massive sulfides: The Iberian Pyrite Belt. Ore Geology Reviews 28, 259-307.

Monitoring the osseointegration process in porous Ti6Al4V implants produced by additive manufacturing: an experimental study in sheep.

PubMed

Kayacan, Mehmet C; Baykal, Yakup B; Karaaslan, Tamer; Özsoy, Koray; Alaca, İlker; Duman, Burhan; Delikanlı, Yunus E

2018-04-01

This study investigated the design and osseointegration process of transitive porous implants that can be used in humans and all trabecular and compact bone structure animals. The aim was to find a way of forming a strong and durable tissue bond on the bone-implant interface. Massive and transitive porous implants were produced on a direct metal laser sintering machine, surgically implanted into the skulls of sheep and kept in place for 12 weeks. At the end of the 12-week period, the Massive and porous implants removed from the sheep were investigated by scanning electron microscopy (SEM) to monitor the osseointegration process. In the literature, each study has selected standard sizes for pore diameter in the structures they use. However, none of these involved transitional porous structures. In this study, as opposed to standard pores, there were spherical or elliptical pores at the micro level, development channels and an inner region. Bone cells developed in the inner region. Transitive pores grown gradually in accordance with the natural structure of the bone were modeled in the inner region for cells to develop. Due to this structure, a strong and durable tissue bond could be formed at the bone-implant interface. Osseointegration processes of Massive vs. porous implants were compared. It was observed that cells were concentrated on the surface of Massive implants. Therefore, osseointegration between implant and bone was less than that of porous implants. In transitive porous implants, as opposed to Massive implants, an outer region was formed in the bone-implant interface that allowed tissue development.

Massive infrared clusters in the Milky Way

NASA Astrophysics Data System (ADS)

Chené, André-Nicolas; Ramírez Alegría, Sebastian; Borissova, Jordanka; Hervé, Anthony; Martins, Fabrice; Kuhn, Michael; Minniti, Dante; VVV Science Team

2017-11-01

Our position in the Milky Way (MW) is both a blessing and a curse. We are nearby to many star clusters, but the dust that is a product of their very existence obscures them. Also, many massive young clusters are expected to be located near, or across the Galactic Center, where the dust extinction is extreme (A V > 15 mag) and can be better penetrated by infrared photons. This paper reviews the discoveries and the study of new MW massive stars and massive clusters made possible by near infrared observations that are part of the VISTA Variables in the Vía Láctea (VVV) survey. It discusses what the studies of their fundamental parameters have taught us.

Gravity localization in sine-Gordon braneworlds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cruz, W.T., E-mail: wilamicruz@gmail.com; Maluf, R.V., E-mail: r.v.maluf@fisica.ufc.br; Sousa, L.J.S., E-mail: luisjose@fisica.ufc.br

2016-01-15

In this work we study two types of five-dimensional braneworld models given by sine-Gordon potentials. In both scenarios, the thick brane is generated by a real scalar field coupled to gravity. We focus our investigation on the localization of graviton field and the behaviour of the massive spectrum. In particular, we analyse the localization of massive modes by means of a relative probability method in a Quantum Mechanics context. Initially, considering a scalar field sine-Gordon potential, we find a localized state to the graviton at zero mode. However, when we consider a double sine-Gordon potential, the brane structure is changedmore » allowing the existence of massive resonant states. The new results show how the existence of an internal structure can aid in the emergence of massive resonant modes on the brane.« less

Galaxy formation

PubMed Central

Peebles, P. J. E.

1998-01-01

It is argued that within the standard Big Bang cosmological model the bulk of the mass of the luminous parts of the large galaxies likely had been assembled by redshift z ∼ 10. Galaxy assembly this early would be difficult to fit in the widely discussed adiabatic cold dark matter model for structure formation, but it could agree with an isocurvature version in which the cold dark matter is the remnant of a massive scalar field frozen (or squeezed) from quantum fluctuations during inflation. The squeezed field fluctuations would be Gaussian with zero mean, and the distribution of the field mass therefore would be the square of a random Gaussian process. This offers a possibly interesting new direction for the numerical exploration of models for cosmic structure formation. PMID:9419326

Paleointensity results for 0 and 3 ka from Hawaiian lava flows: a new approach to sampling

NASA Astrophysics Data System (ADS)

Cromwell, G.; Tauxe, L.; Staudigel, H.; Ron, H.; Trusdell, F.

2011-12-01

Paleointensity data are typically generated from core samples drilled out of the massive parts of lava flows. During Thellier-Thellier type experiments, these massive samples suffer from very low success rates (~20%), as shown by failure to meet statistical criteria. Low success generally occurs for two reasons: 1) alteration of the sample during the heating process, and 2) multi-domain behavior of massive material. Moreover, recent studies of historical lava flows show that massive samples may not accurately reflect the intensity of the magnetic field even when they are successful (Valet et al., 2010). Alternatively, submarine basaltic glasses (SBG) produce high success rates (~80%) for Thellier-Thellier type experiments, likely due to near instantaneous cooling rates which produce single-domain magnetic grains. In addition, SBG have been proven to produce accurate records of the magnetic field (e.g., Pick and Tauxe, 1993). In this study we investigate the success of paleointensity experiments on subaerial quenched basalts from Hawaii in the quest for single domain, rapidly cooled subaerial analogs to SBG. We also examine the effects of grain size and cooling rate on the accuracy of paleointensity results. During March 2011, we collected samples from 31 dated lava flows (0-3360 BP), including the [historical] 1950 C.E. and 2010 C.E. flows. Each lava flow was additionally subsampled when unique cooling structures within the unit could be identified. Results from the 1950 and 2010 glasses accurately record the expected geomagnetic field strength. We will present results of a comprehensive data set of Hawaiian paleointensity focused on about the last 3 ka.

Mapping Dark Matter in Simulated Galaxy Clusters

NASA Astrophysics Data System (ADS)

Bowyer, Rachel

2018-01-01

Galaxy clusters are the most massive bound objects in the Universe with most of their mass being dark matter. Cosmological simulations of structure formation show that clusters are embedded in a cosmic web of dark matter filaments and large scale structure. It is thought that these filaments are found preferentially close to the long axes of clusters. We extract galaxy clusters from the simulations "cosmo-OWLS" in order to study their properties directly and also to infer their properties from weak gravitational lensing signatures. We investigate various stacking procedures to enhance the signal of the filaments and large scale structure surrounding the clusters to better understand how the filaments of the cosmic web connect with galaxy clusters. This project was supported in part by the NSF REU grant AST-1358980 and by the Nantucket Maria Mitchell Association.

Color Magnitude Diagrams of Old, Massive GCs in M31

NASA Astrophysics Data System (ADS)

Caldwell, Nelson; Williams, B.; Dolphin, A. E.; Johnson, L. C.; Weisz, D. R.

2013-01-01

Multicolor stellar photometry of HST data of M31 collected as part of the PHAT project has been performed using the DOLPHOT suite of programs. We present results of color-magnitude diagrams created in F475W and F814W (BI) of more than 50 massive, old clusters. These are clusters in or projected on the disk. We compare the metallicities derived from the color of the giant branch stars with that derived from integrated light spectroscopy. As well, we compare the ages of massive, young clusters with those found from spectra.

3D numerical calculations and synthetic observations of magnetized massive dense core collapse and fragmentation.

NASA Astrophysics Data System (ADS)

Commerçon, B.; Hennebelle, P.; Levrier, F.; Launhardt, R.; Henning, Th.

2012-03-01

I will present radiation-magneto-hydrodynamics calculations of low-mass and massive dense core collapse, focusing on the first collapse and the first hydrostatic core (first Larson core) formation. The influence of magnetic field and initial mass on the fragmentation properties will be investigated. In the first part reporting low mass dense core collapse calculations, synthetic observations of spectral energy distributions will be derived, as well as classical observational quantities such as bolometric temperature and luminosity. I will show how the dust continuum can help to target first hydrostatic cores and to state about the nature of VeLLOs. Last, I will present synthetic ALMA observation predictions of first hydrostatic cores which may give an answer, if not definitive, to the fragmentation issue at the early Class 0 stage. In the second part, I will report the results of radiation-magneto-hydrodynamics calculations in the context of high mass star formation, using for the first time a self-consistent model for photon emission (i.e. via thermal emission and in radiative shocks) and with the high resolution necessary to resolve properly magnetic braking effects and radiative shocks on scales <100 AU (Commercon, Hennebelle & Henning ApJL 2011). In this study, we investigate the combined effects of magnetic field, turbulence, and radiative transfer on the early phases of the collapse and the fragmentation of massive dense cores (M=100 M_⊙). We identify a new mechanism that inhibits initial fragmentation of massive dense cores, where magnetic field and radiative transfer interplay. We show that this interplay becomes stronger as the magnetic field strength increases. We speculate that highly magnetized massive dense cores are good candidates for isolated massive star formation, while moderately magnetized massive dense cores are more appropriate to form OB associations or small star clusters. Finally we will also present synthetic observations of these collapsing massive dense cores.

Sediment depositions upstream of open check dams: new elements from small scale models

NASA Astrophysics Data System (ADS)

Piton, Guillaume; Le Guern, Jules; Carbonari, Costanza; Recking, Alain

2015-04-01

Torrent hazard mitigation remains a big issue in mountainous regions. In steep slope streams and especially in their fan part, torrential floods mainly result from abrupt and massive sediment deposits. To curtail such phenomenon, soil conservation measures as well as torrent control works have been undertaken for decades. Since the 1950s, open check dams complete other structural and non-structural measures in watershed scale mitigation plans1. They are often built to trap sediments near the fan apexes. The development of earthmoving machinery after the WWII facilitated the dredging operations of open check dams. Hundreds of these structures have thus been built for 60 years. Their design evolved with the improving comprehension of torrential hydraulics and sediment transport; however this kind of structure has a general tendency to trap most of the sediments supplied by the headwaters. Secondary effects as channel incision downstream of the traps often followed an open check dam creation. This sediment starvation trend tends to propagate to the main valley rivers and to disrupt past geomorphic equilibriums. Taking it into account and to diminish useless dredging operation, a better selectivity of sediment trapping must be sought in open check dams, i.e. optimal open check dams would trap sediments during dangerous floods and flush them during normal small floods. An accurate description of the hydraulic and deposition processes that occur in sediment traps is needed to optimize existing structures and to design best-adjusted new structures. A literature review2 showed that if design criteria exist for the structure itself, little information is available on the dynamic of the sediment depositions upstream of open check dams, i.e. what are the geomorphic patterns that occur during the deposition?, what are the relevant friction laws and sediment transport formula that better describe massive depositions in sediment traps?, what are the range of Froude and Shields numbers that the flows tend to adopt? New small scale model experiments have been undertaken focusing on depositions processes and their related hydraulics. Accurate photogrammetric measurements allowed us to better describe the deposition processes3. Large Scale Particle Image Velocimetry (LS-PIV) was performed to determine surface velocity fields in highly active channels with low grain submersion4. We will present preliminary results of our experiments showing the new elements we observed in massive deposit dynamics. REFERENCES 1.Armanini, A., Dellagiacoma, F. & Ferrari, L. From the check dam to the development of functional check dams. Fluvial Hydraulics of Mountain Regions 37, 331-344 (1991). 2.Piton, G. & Recking, A. Design of sediment traps with open check dams: a review, part I: hydraulic and deposition processes. (Accepted by the) Journal of Hydraulic Engineering 1-23 (2015). 3.Le Guern, J. Ms Thesis: Modélisation physique des plages de depot : analyse de la dynamique de remplissage.(2014) . 4.Carbonari, C. Ms Thesis: Small scale experiments of deposition processes occuring in sediment traps, LS-PIV measurments and geomorphological descriptions. (in preparation).

Two-dimensional modeling of density and thermal structure of dense circumstellar outflowing disks

NASA Astrophysics Data System (ADS)

Kurfürst, P.; Feldmeier, A.; Krtička, J.

2018-06-01

Context. Evolution of massive stars is affected by a significant loss of mass either via (nearly) spherically symmetric stellar winds or by aspherical mass-loss mechanisms, namely the outflowing equatorial disks. However, the scenario that leads to the formation of a disk or rings of gas and dust around massive stars is still under debate. It is also unclear how various forming physical mechanisms of the circumstellar environment affect its shape and density, as well as its kinematic and thermal structure. Aims: We study the hydrodynamic and thermal structure of optically thick, dense parts of outflowing circumstellar disks that may be formed around various types of critically rotating massive stars, for example, Be stars, B[e] supergiant (sgB[e]) stars or Pop III stars. We calculate self-consistent time-dependent models of temperature and density structure in the disk's inner dense region that is strongly affected by irradiation from a rotationally oblate central star and by viscous heating. Methods: Using the method of short characteristics, we specify the optical depth of the disk along the line-of-sight from stellar poles. Within the optically thick dense region with an optical depth of τ > 2/3 we calculate the vertical disk thermal structure using the diffusion approximation while for the optically thin outer layers we assume a local thermodynamic equilibrium with the impinging stellar irradiation. For time-dependent hydrodynamic modeling, we use two of our own types of hydrodynamic codes: two-dimensional operator-split numerical code based on an explicit Eulerian finite volume scheme on a staggered grid, and unsplit code based on the Roe's method, both including full second-order Navier-Stokes shear viscosity. Results: Our models show the geometric distribution and contribution of viscous heating that begins to dominate in the central part of the disk for mass-loss rates higher than Ṁ ≳ 10-10 M⊙ yr-1. In the models of dense viscous disks with Ṁ > 10-8 M⊙ yr-1, the viscosity increases the central temperature up to several tens of thousands of Kelvins, however the temperature rapidly drops with radius and with distance from the disk midplane. The high mass-loss rates and high viscosity lead to instabilities with significant waves or bumps in density and temperature in the very inner disk region. Conclusions: The two-dimensional radial-vertical models of dense outflowing disks including the full Navier-Stokes viscosity terms show very high temperatures that are however limited to only the central disk cores inside the optically thick area, while near the edge of the optically thick region the temperature may be low enough for the existence of neutral hydrogen, for example.

Cosmology on a Mesh

NASA Astrophysics Data System (ADS)

Gill, Stuart P. D.; Knebe, Alexander; Gibson, Brad K.; Flynn, Chris; Ibata, Rodrigo A.; Lewis, Geraint F.

2003-04-01

An adaptive multi grid approach to simulating the formation of structure from collisionless dark matter is described. MLAPM (Multi-Level Adaptive Particle Mesh) is one of the most efficient serial codes available on the cosmological "market" today. As part of Swinburne University's role in the development of the Square Kilometer Array, we are implementing hydrodynamics, feedback, and radiative transfer within the MLAPM adaptive mesh, in order to simulate baryonic processes relevant to the interstellar and intergalactic media at high redshift. We will outline our progress to date in applying the existing MLAPM to a study of the decay of satellite galaxies within massive host potentials.

Resolving the Massive Binary Wind Interaction Of Eta Carinae with HST/STIS

NASA Technical Reports Server (NTRS)

Gull, Theodore; Nielsen, K.; Corcoran, M.; Hillier, J.; Madura, T.; Hamaguchi, K.; Kober, G.; Owocki, S.; Russell, C.; Okazaki, A.;

Implementation of molecular dynamics and its extensions with the coarse-grained UNRES force field on massively parallel systems; towards millisecond-scale simulations of protein structure, dynamics, and thermodynamics

PubMed Central

Liwo, Adam; Ołdziej, Stanisław; Czaplewski, Cezary; Kleinerman, Dana S.; Blood, Philip; Scheraga, Harold A.

2010-01-01

We report the implementation of our united-residue UNRES force field for simulations of protein structure and dynamics with massively parallel architectures. In addition to coarse-grained parallelism already implemented in our previous work, in which each conformation was treated by a different task, we introduce a fine-grained level in which energy and gradient evaluation are split between several tasks. The Message Passing Interface (MPI) libraries have been utilized to construct the parallel code. The parallel performance of the code has been tested on a professional Beowulf cluster (Xeon Quad Core), a Cray XT3 supercomputer, and two IBM BlueGene/P supercomputers with canonical and replica-exchange molecular dynamics. With IBM BlueGene/P, about 50 % efficiency and 120-fold speed-up of the fine-grained part was achieved for a single trajectory of a 767-residue protein with use of 256 processors/trajectory. Because of averaging over the fast degrees of freedom, UNRES provides an effective 1000-fold speed-up compared to the experimental time scale and, therefore, enables us to effectively carry out millisecond-scale simulations of proteins with 500 and more amino-acid residues in days of wall-clock time. PMID:20305729

Secular resonances with massive asteroids and their impact on the dynamics of small bodies

NASA Astrophysics Data System (ADS)

Tsirvoulis, Georgios; Novaković, Bojan; Djošović, Valdimir

2015-08-01

The quest for understanding the dynamical structure of the main belt has been a long-lasting endeavor. From the discovery of the Kirkwood gaps and the Hirayama families, to the more recent advances in secular perturbation theory, the refinement of the proper elements and the discovery of the three-body mean-motion resonances, only to name a few, the progress has been immense. Dynamical models coupled with the outbursts in computational power and observations have greatly improved our knowledge of the dynamical evolution of the small bodies in the Solar System.While our set of tools for studying the dynamical porperties of the main belt is believed to be sufficiently complete, our assumptions on how to use them seem to have hindered this effort.The concensus has been that, judging by their mass, only the planets, especially the giant ones, can act as efficient perturbers of the orbits of asteroids. Thus a lot of studies have been made on the locations and effects of secular resonances with the giant planets in different parts of the main belt, explaining among other things the presence of gaps in the distribution of asteroids, strange shapes of some asteroid families and transport mechanisms of asteroids to the near-Earth region.Our work is motivated by the first discovery that a secular resonance with the most massive asteroid, Ceres, is the dominant dynamical mechanism responsible for the post-impact evolution of the Hoffmeister family members. Thus the concensus is wrong. Knowing now, that secular resonances with massive asteroids can be effective on asteroid dynamics, we set out to construct a dynamical map of these resonances across the main belt.Our study is focused on the linear and degree four non-linear secular resonances with the two most massive asteroids (1) Ceres and (4) Vesta. First we determine the locations of these secular resonances in the proper elements space, acquiring an understanding of the potentially affected regions, and then we perform numerical simulations to investigate the importance of each secular resonance on the dynamical evolution of asteroid orbits in the different parts of the main belt.

Embeddings of the "New Massive Gravity"

NASA Astrophysics Data System (ADS)

Dalmazi, D.; Mendonça, E. L.

2016-07-01

Here we apply different types of embeddings of the equations of motion of the linearized "New Massive Gravity" in order to generate alternative and even higher-order (in derivatives) massive gravity theories in D=2+1. In the first part of the work we use the Weyl symmetry as a guiding principle for the embeddings. First we show that a Noether gauge embedding of the Weyl symmetry leads to a sixth-order model in derivatives with either a massive or a massless ghost, according to the chosen overall sign of the theory. On the other hand, if the Weyl symmetry is implemented by means of a Stueckelberg field we obtain a new scalar-tensor model for massive gravitons. It is ghost-free and Weyl invariant at the linearized level around Minkowski space. The model can be nonlinearly completed into a scalar field coupled to the NMG theory. The elimination of the scalar field leads to a nonlocal modification of the NMG. In the second part of the work we prove to all orders in derivatives that there is no local, ghost-free embedding of the linearized NMG equations of motion around Minkowski space when written in terms of one symmetric tensor. Regarding that point, NMG differs from the Fierz-Pauli theory, since in the latter case we can replace the Einstein-Hilbert action by specific f(R,Box R) generalizations and still keep the theory ghost-free at the linearized level.

VizieR Online Data Catalog: Properties of OB associations in IC 1613 (Garcia+, 2010)

NASA Astrophysics Data System (ADS)

Garcia, M.; Herrero, A.; Castro, N.; Corral, L.; Rosenberg, A.

2014-06-01

To understand the structure and evolution of massive stars, systematic surveys of the Local Group galaxies have been undertaken, to find these objects in environments of different chemical abundances. We focus on the metal-poor irregular galaxy IC 1613 to analyze the stellar and wind structure of its low-metallicity massive stars. We ultimately aim to study the metallicity-dependent driving mechanism of the winds of blue massive stars and use metal-poor massive stars of the Local Volume as a proxy for the stars in the early Universe. In a previous paper we produced a list of OB associations in IC 1613. Their properties are not only a powerful aid towards finding the most interesting candidate massive stars, but also reveal the structure and recent star formation history of the galaxy. We characterize these OB associations and study their connection with the galactic global properties. The reddening-free Q parameter is a powerful tool in the photometric analysis of young populations of massive stars, since it exhibits a smaller degree of degeneracy with OB spectral types than the B-V color. The color-magnitude diagram (Q vs. V) of the OB associations in IC 1613 is studied to determine their age and mass, and confirm the population of young massive stars. We identified more than 10 stars with M>=50M⊙. Spectral classification available for some of them confirm their massive nature, yet we find the common discrepancy with the spectroscopically derived masses. There is a general increasing trend of the mass of the most massive member with the number of members of each association, but not with the stellar density. The average diameter of the associations of this catalog is 40pc, half the historically considered typical size of OB associations. Size increases with the association population. The distribution of the groups strongly correlates with that of neutral and ionized hydrogen. We find the largest dispersion of association ages in the bubble region of the galaxy where hydrogen is abundant, implying that recent star formation has proceeded over a longer period of time than in the rest of the galaxy, and is still ongoing. Very young associations are found at the west of the galaxy far from the bubble region, traditionally considered the sole locus of star formation, but still rich in neutral hydrogen. The contrast in the stellar properties derived from photometry and spectroscopy (when the latter is available) shows that the Q pseudo-color is very useful for estimating the parameters of OB stars when only photometric observations exist. This work helped define an extensive pool of candidate OB stars for subsequent spectroscopic analyses designed to study the structure and winds of metal-poor massive stars. (2 data files).

Applications of the Cambridge Structural Database in chemical education1

PubMed Central

Battle, Gary M.; Ferrence, Gregory M.; Allen, Frank H.

2010-01-01

The Cambridge Structural Database (CSD) is a vast and ever growing compendium of accurate three-dimensional structures that has massive chemical diversity across organic and metal–organic compounds. For these reasons, the CSD is finding significant uses in chemical education, and these applications are reviewed. As part of the teaching initiative of the Cambridge Crystallographic Data Centre (CCDC), a teaching subset of more than 500 CSD structures has been created that illustrate key chemical concepts, and a number of teaching modules have been devised that make use of this subset in a teaching environment. All of this material is freely available from the CCDC website, and the subset can be freely viewed and interrogated using WebCSD, an internet application for searching and displaying CSD information content. In some cases, however, the complete CSD System is required for specific educational applications, and some examples of these more extensive teaching modules are also discussed. The educational value of visualizing real three-dimensional structures, and of handling real experimental results, is stressed throughout. PMID:20877495

Applications of the Cambridge Structural Database in chemical education.

PubMed

Battle, Gary M; Ferrence, Gregory M; Allen, Frank H

2010-10-01

The Cambridge Structural Database (CSD) is a vast and ever growing compendium of accurate three-dimensional structures that has massive chemical diversity across organic and metal-organic compounds. For these reasons, the CSD is finding significant uses in chemical education, and these applications are reviewed. As part of the teaching initiative of the Cambridge Crystallographic Data Centre (CCDC), a teaching subset of more than 500 CSD structures has been created that illustrate key chemical concepts, and a number of teaching modules have been devised that make use of this subset in a teaching environment. All of this material is freely available from the CCDC website, and the subset can be freely viewed and interrogated using WebCSD, an internet application for searching and displaying CSD information content. In some cases, however, the complete CSD System is required for specific educational applications, and some examples of these more extensive teaching modules are also discussed. The educational value of visualizing real three-dimensional structures, and of handling real experimental results, is stressed throughout.

An investigation of the Carina Nebula

NASA Astrophysics Data System (ADS)

Brooks, Kate J.

2000-10-01

It is well known that the radiation fields and stellar winds of massive stars can drastically affect the physical conditions, structure and chemistry of the giant molecular cloud (GMC) from which they formed. It is also thought that massive stars are at least partly responsible for triggering further star formation within a GMC. The details of this interaction, however, are not well understood and additional detailed study of massive star-forming regions is needed. This study has focused on a multi-wavelength investigation of the Carina Nebula. This is a spectacular massive star-forming region that contains two of the most massive star clusters in our galaxy, Trumpler 14 and Trumpler 16, and one of the most massive stars known -- η Car. The goal of this study has been to obtain information on the molecular gas, ionized gas and photodissociation regions (PDRs) from a collection of instruments which have the highest angular resolution and sensitivity available to date. The Mopra Telescope and the Swedish-ESO Submillimeter Telescope (SEST) were used to obtain a series of molecular line observations of the GMC between 150 and 230 GHz. Observations of H110α recombination-line emission at 4.874 GHz and the related continuum emission were obtained with the Australia Telescope Compact Array and used to study the ionized gas associated with the two HII regions, Car I and Car II. H2 1--0 S(1) (2.12 microns) and Brγ (2.16 microns) observations using the University of New South Wales Infrared Fabry-Perot (UNSWIRF) and 3.29 micron narrow-band observations obtained with the SPIREX/Abu thermal infrared camera were used to study the PDRs on the surface of molecular clumps in the Keyhole region, a dark optical feature in the vicinity of η Car. The results of these observations provide detailed information on the excitation conditions, kinematics and morphology of regions within the HII region/molecular cloud complex of the Carina Nebula. In addition, the results confirm that the Carina Nebula is one of the most extreme and complex cases of massive stars interacting with their environment and show that there is still a wealth of information to be gained from future studies of this region. %% If you have your thesis on the web, please provide the web address here Copies currently available at: http://www.atnf.csiro.au/people/kbrooks/html/publications.html

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, Fred C., E-mail: fca@umich.edu

This paper develops constraints on the values of the fundamental constants that allow universes to be habitable. We focus on the fine structure constant α and the gravitational structure constant α{sub G}, and find the region in the α-α{sub G} plane that supports working stars and habitable planets. This work is motivated, in part, by the possibility that different versions of the laws of physics could be realized within other universes. The following constraints are enforced: [A] long-lived stable nuclear burning stars exist, [B] planetary surface temperatures are hot enough to support chemical reactions, [C] stellar lifetimes are long enoughmore » to allow biological evolution, [D] planets are massive enough to maintain atmospheres, [E] planets are small enough in mass to remain non-degenerate, [F] planets are massive enough to support sufficiently complex biospheres, [G] planets are smaller in mass than their host stars, and [H] stars are smaller in mass than their host galaxies. This paper delineates the portion of the α-α{sub G} plane that satisfies all of these constraints. The results indicate that viable universes—with working stars and habitable planets—can exist within a parameter space where the structure constants α and α{sub G} vary by several orders of magnitude. These constraints also provide upper bounds on the structure constants (α,α{sub G}) and their ratio. We find the limit α{sub G}/α ∼< 10{sup −34}, which shows that habitable universes must have a large hierarchy between the strengths of the gravitational force and the electromagnetic force.« less

Condensate of massive graviton and dark matter

NASA Astrophysics Data System (ADS)

Aoki, Katsuki; Maeda, Kei-ichi

2018-02-01

We study coherently oscillating massive gravitons in the ghost-free bigravity theory. This coherent field can be interpreted as a condensate of the massive gravitons. We first define the effective energy-momentum tensor of the coherent massive gravitons in a curved spacetime. We then study the background dynamics of the Universe and the cosmic structure formation including the effects of the coherent massive gravitons. We find that the condensate of the massive graviton behaves as a dark matter component of the Universe. From the geometrical point of view the condensate is regarded as a spacetime anisotropy. Hence, in our scenario, dark matter is originated from the tiny deformation of the spacetime. We also discuss a production of the spacetime anisotropy and find that the extragalactic magnetic field of a primordial origin can yield a sufficient amount for dark matter.

Interpretation of massive sandstones in ephemeral fluvial settings: A case study from the Upper Candelária Sequence (Upper Triassic, Paraná Basin, Brazil)

NASA Astrophysics Data System (ADS)

Horn, Bruno Ludovico Dihl; Goldberg, Karin; Schultz, Cesar Leandro

2018-01-01

Ephemeral rivers display a wide range of upper- and lower-flow regime structures due to great flow-velocity changes during the floods. The development of flow structures in these setting is yet to be understood, especially in the formation of thick, massive sandstones. The Upper Triassic of Southern Gondwana was marked by a climate with great seasonal changes, yet there is no description of river systems with seasonal characteristics in Southern Gondwana. This work aims to characterize a ephemeral alluvial system of the Upper Triassic of the Paraná Basin. The characteristics of the deposits are discussed in terms of depositional processes through comparison with similar deposits from literature, flow characteristics and depositional signatures compared to flume experiments. The alluvial system is divided in four facies associations: (1) channels with wanning fill, characterized by low width/thickness ratio, tabular bodies, scour-and-fill structures with upper- and lower-flow regime bedforms; (2) channels with massive fill, characterized by low w/t ratio, sheet-like bodies, scour-and-fill structures with massive sandstones; (3) proximal sheetfloods, characterized by moderate w/t ratio, sheet-like bodies with upper- and lower-flow regime bedforms and (4) distal sheetfloods, characterized by high w/t ratio, sheet-like bodies with lower-flow regime bedforms. Evidence for the seasonal reactivation of the riverine system includes the scarcity of well-developed macroforms and presence of in-channel mudstones, thick intraformational conglomerates, and the occurrence of well- and poorly-preserved vertebrate bones in the same beds. The predominantly massive sandstones indicate deposition from a hyperconcentrated flow during abrupt changes in flow speed, caused by de-confinement or channel avulsion, whereas turbulent portions of the flow formed the upper- and lower-flow regime bedforms after the deposition of the massive layers. The upper portion of the Candelária Sequence records a good example of strongly ephemeral alluvial systems, where the predominance of massive sandstones is a particular characteristic.

Helping Aircraft Engines Lighten Up

NASA Technical Reports Server (NTRS)

2004-01-01

High-temperature polyimide/carbon fiber matrix composites are developed by the Polymers Branch at NASA's Glenn Research Center. These materials can withstand high temperatures and have good processing properties, which make them particularly useful for jet and rocket engines and for components such as fan blades, bushings, and duct segments. Applying polyimide composites as components for aerospace structures can lead to substantial vehicle weight reductions. A typical polyimide composite is made up of layers of carbon or glass fibers glued together by a high-temperature polymer to make the material strong, stiff, and lightweight. Organic molecules containing carbon, nitrogen, oxygen, and hydrogen within the polyimide keep the material s density low, resulting in the light weight. The strength of a component or part made from a polyimide comes mainly from the reinforcing high-strength fibers. The strength of the carbon fibers coupled with the stiffness of polyimides allows engineers to make a very rigid structure without it being massive. Another benefit of a polyimide s suitability for aerospace applications is its reduced need for machining. When polyimide parts are removed from a mold, they are nearly in their final shape. Usually, very little machining is needed before a part is ready for use.

Large mammal burrows in late Miocene calcic paleosols from central Argentina: paleoenvironment, taphonomy and producers.

PubMed

Cardonatto, María Cristina; Melchor, Ricardo Néstor

2018-01-01

Large cylindrical sediment-filled structures interpreted as mammal burrows occur within the loess-paleosol sequence of the late Miocene Cerro Azul Formation of central Argentina. A total of 115 burrow fills from three localities were measured. They are typically shallowly dipping, subcylindrical, unbranched structures with rounded ends and lacking enlargements. The horizontal diameter of the burrows range between 0.15 and 1.50 m, with most of the burrows in the interval of 0.39 to 0.98 m. Geometric morphometric analysis of transverse cross-sections support their distinct subcircular and elliptical (horizontally flattened) shapes. Burrow fills are typically laminated in the lower part and massive in the upper part. The laminated intervals reflect pulses of flowing water entering the abandoned burrow during moderate rains, whereas massive intervals reflect mass flow input of dense sediment-water mixtures during heavy rains that produced sheet floods. Approximately 1% of the burrows contained fragmentary, disarticulated and weathered mammal bones that were introduced in the open burrow by currents along with other sedimentary particles. Analysis of the tetrapod burrow fossil record suggests that Miocene burrows, including those studied herein, reflect a remarkable increase in the average size of the fossorial fauna. We conclude that large late Miocene mammals dug burrows essentially as a shelter against environmental extremes and to escape predation. The simple architecture of the burrows suggests that the producers essentially foraged aboveground. Several mammal groups acquired fossorial habits in response to cold and seasonally dry climatic conditions that prevailed during the late Miocene in southern South America. The considerable range of horizontal diameters of the studied burrows can be attributed to a variety of producers, including dasypodids, the notoungulate Paedotherium minor , Glyptodontidae and Proscelidodon sp.

Comparative Analysis of Data Structures for Storing Massive Tins in a Dbms

NASA Astrophysics Data System (ADS)

Kumar, K.; Ledoux, H.; Stoter, J.

2016-06-01

Point cloud data are an important source for 3D geoinformation. Modern day 3D data acquisition and processing techniques such as airborne laser scanning and multi-beam echosounding generate billions of 3D points for simply an area of few square kilometers. With the size of the point clouds exceeding the billion mark for even a small area, there is a need for their efficient storage and management. These point clouds are sometimes associated with attributes and constraints as well. Storing billions of 3D points is currently possible which is confirmed by the initial implementations in Oracle Spatial SDO PC and the PostgreSQL Point Cloud extension. But to be able to analyse and extract useful information from point clouds, we need more than just points i.e. we require the surface defined by these points in space. There are different ways to represent surfaces in GIS including grids, TINs, boundary representations, etc. In this study, we investigate the database solutions for the storage and management of massive TINs. The classical (face and edge based) and compact (star based) data structures are discussed at length with reference to their structure, advantages and limitations in handling massive triangulations and are compared with the current solution of PostGIS Simple Feature. The main test dataset is the TIN generated from third national elevation model of the Netherlands (AHN3) with a point density of over 10 points/m2. PostgreSQL/PostGIS DBMS is used for storing the generated TIN. The data structures are tested with the generated TIN models to account for their geometry, topology, storage, indexing, and loading time in a database. Our study is useful in identifying what are the limitations of the existing data structures for storing massive TINs and what is required to optimise these structures for managing massive triangulations in a database.

The Anemic Stellar Halo of M101

NASA Astrophysics Data System (ADS)

Holwerda, Benne

2014-10-01

Models of galaxy formation in a cosmological context predict that massive disk galaxies should have richly-structured extended stellar halos, containing ~10% of a galaxy's stars, originating in large part from the tidal disruption of dwarf galaxies. Observations of a number of nearby disk galaxies have generally agreed with these expectations. Recent new observations in integrated light with a novel array of low scattered-light telephoto lenses have failed to convincingly detect a stellar halo in the nearby massive face-on disk galaxy M101 (van Dokkum et al. 2014). They argue that any halo has to have <0.3% of the mass of the galaxy. This halo would be the least massive of any massive disk galaxy in the local Universe (by factors of several) -- such a halo is not predicted or naturally interpreted by the models, and would present a critical challenge to the picture of ubiquitous stellar halos formed from the debris of disrupting dwarf galaxies.We propose to resolve the stellar populations of this uniquely anemic stellar halo for 6 orbits with HST (ACS and WFC3), allowing us to reach surface brightness limits sufficient to clearly detect and characterize M101's stellar halo if it carries more than 0.1% of M101's mass. With resolved stellar populations, we can use the gradient of stellar populations as a function of radius to separate stellar halo from disk, which is impossible using integrated light observations. The resolved stellar populations will reveal the halo mass to much greater accuracy, measure the halo radial profile, constrain any halo lopsidedness, estimate the halo's stellar metallicity, and permit an analysis of outer disk stellar populations.

Mineralogy, chemical composition and structure of the MIR Mound, TAG Hydrothermal Field

NASA Astrophysics Data System (ADS)

Stepanova, T. V.; Krasnov, S. G.; Cherkashev, G. A.

The study of samples collected from the surface of the MIR mound (TAG Hydrothermal Field) by video-controlled hydraulic grab allowed identification of a number of mineralogical types. These include pyrite-chalcopyrite (Py-Cp), bornite-chalcopyrite-opaline (Bn-Cp-Op) and sphalerite-opaline (Sp-Op) sulfide chimneys, massive sulfides composed of pyrite (Py), chalcopyrite-pyrite (Cp-Py), marcasite-pyrite-opaline (Mc-Py-Op), sphalerite-pyrite-opaline (Sp-Py-Op) and sphalerite-chalcopyrite-pyrite-opaline (Sp-Cp-Py-Op), as well as siliceous and Fe-Mn oxide hydrothermal deposits. Most of the minor elements (Ag, Au, Cd, Ga, Hg, Sb and Pb) are associated with Zn-rich massive sulfides, Co Bi, Pb, and As with Ferich ones, while Cu-rich sulfides are depleted of trace metals. Cu-enriched assemblages are concentrated in the northern part, Zn-enriched in the center, and siliceous rocks in the south of the MIR mound. According to paragenetic relations, the development of the mound started with the formation of quartz (originally opaline) rocks and dendritic assemblages of melnikovite-pyrite, followed by deposition of chalcopyrite and recrystallization of primary pyrite, subsequent generation of sphalerite-rich assemblages and final deposition of opaline rocks. The late renewal of hydrothermal activity led to local formation of Cu-rich chimneys enriched in Au, Ag, Hg and Pb probably due to their remobilization from inner parts of the deposit.

A starburst region at the tip of the Galactic bar around l=347-350

NASA Astrophysics Data System (ADS)

Marco, Amparo; Negueruela, Ignacio; González-Fernández, Carlos; Maíz-Apellániz, Jesús; Dorda, Ricardo; Clark, J. Simon

2015-08-01

In the past few years, several clusters of red supergiants have been discovered in a small region of the Milky Way, close to the base of the Scutum-Crux Arm and the tip of the Long Bar, between l=24º and l=29º. According to the number of observed red supergiants and using population synthesis models, they must contain very large stellar populations to harbour so many RSGs, some of them being candidates to the most massive young clusters in the Galaxy. These massive open clusters are part of a huge structure most likely containing hundreds of red supergiants. These results suggest that the Scutum complex represents a giant star formation region triggered by dynamical excitation by the Galactic bar, whose tip is believed to intersect the Scutum-Crux Arm close to this region. If this scenario is correct, a similar structure would be expected close to the opposite end of the Galactic long bar. We must find in an area between l=347º-350º (these sight lines include the expected location of the far tip of the Galactic bar in the model of González-Fernández et al. (2012)) likely candidates to very massive open clusters.We are carrying out a comprehensive optical and infrared photometric and spectroscopic study of this region containing the open clusters VdBH 222, Teutsch 85 and their surroundings. We have analyzed the population of VdBH 222 and we have found a large population of luminous supergiants and OB stars. The cluster lies behind ~7.5 mag of extinction and has a probable distance of ~ 10 kpc and an age of ~12 Ma. VdBH 222 is a young massive cluster with a likely mass > 20000 Msolar. Now, we are analyzing the population of the open cluster Teutsch 85 and surroundings, finding a numerous population of supergiants.In this work, we will discuss the possible role of the Galactic bar in triggering the formation of starburst clusters.

Integrands for QCD rational terms and {N} = {4} SYM from massive CSW rules

NASA Astrophysics Data System (ADS)

Elvang, Henriette; Freedman, Daniel Z.; Kiermaier, Michael

2012-06-01

We use massive CSW rules to derive explicit compact expressions for integrands of rational terms in QCD with any number of external legs. Specifically, we present all- n integrands for the one-loop all-plus and one-minus gluon amplitudes in QCD. We extract the finite part of spurious external-bubble contributions systematically; this is crucial for the application of integrand-level CSW rules in theories without supersymmetry. Our approach yields integrands that are independent of the choice of CSW reference spinor even before integration. Furthermore, we present a recursive derivation of the recently proposed massive CSW-style vertex expansion for massive tree amplitudes and loop integrands on the Coulomb-branch of {N} = {4} SYM. The derivation requires a careful study of boundary terms in all-line shift recursion relations, and provides a rigorous (albeit indirect) proof of the recently proposed construction of massive amplitudes from soft-limits of massless on-shell amplitudes. We show that the massive vertex expansion manifestly preserves all holomorphic and half of the anti-holomorphic supercharges, diagram-by-diagram, even off-shell.

Formation of large-scale structure from cosmic strings and massive neutrinos

NASA Technical Reports Server (NTRS)

Scherrer, Robert J.; Melott, Adrian L.; Bertschinger, Edmund

1989-01-01

Numerical simulations of large-scale structure formation from cosmic strings and massive neutrinos are described. The linear power spectrum in this model resembles the cold-dark-matter power spectrum. Galaxy formation begins early, and the final distribution consists of isolated density peaks embedded in a smooth background, leading to a natural bias in the distribution of luminous matter. The distribution of clustered matter has a filamentary appearance with large voids.

Graft Utilization in the Augmentation of Large-to-Massive Rotator Cuff Repairs: A Systematic Review.

PubMed

Ferguson, Devin P; Lewington, Matthew R; Smith, T Duncan; Wong, Ivan H

2016-11-01

Current treatment options for symptomatic large-to-massive rotator cuff tears can reduce pain, but failure rates remain high. Surgeons have incorporated synthetic and biologic grafts to augment these repairs, with promising results. Multiple reviews exist that summarize these products; however, no systematic review has investigated the grafts' ability to maintain structural integrity after augmentation of large-to-massive rotator cuff repairs. To systematically review and evaluate the effectiveness of grafts in the augmentation of large-to-massive rotator cuff repairs. Systematic review. A comprehensive search of 4 reputable databases was completed. Inclusion criteria were (1) large-to-massive rotator cuff tear, (2) graft augmentation of primary repairs ± primary repair control group, and (3) minimum clinical and radiologic follow-up of 12 months. Two reviewers screened the titles, abstracts, and full articles and extracted the data from eligible studies. Results were summarized into evidence tables stratified by graft origin and level of evidence. Ten studies fit the inclusion criteria. Allograft augmentation was functionally and structurally superior to primary repair controls, with intact repairs in 85% versus 40% of patients (P < .01). This was supported by observational study data. Xenograft augmentation failed to demonstrate superiority to primary repair controls, with worse structural healing rates (27% vs 60%; P =.11). Both comparative studies supported this finding. There have also been many reports of inflammatory reactions with xenograft use. Polypropylene patches are associated with improved structural (83% vs 59% and 49%; P < .01) and functional outcomes when compared with controls and xenograft augmentation; however, randomized data are lacking. Augmentation of large-to-massive rotator cuff repairs with human dermal allografts is associated with superior functional and structural outcome when compared with conventional primary repair. Xenograft augmentation failed to demonstrate a statistically significant difference and may be associated with worse rerupture rates and occasional severe inflammatory reactions. Polypropylene patches have initial promising results. Research in this field is limited; future researchers should continue to develop prospective, randomized controlled trials to establish clear recommendations. © 2016 The Author(s).

Differentiation of the asteroid Ceres as revealed by its shape.

PubMed

Thomas, P C; Parker, J Wm; McFadden, L A; Russell, C T; Stern, S A; Sykes, M V; Young, E F

2005-09-08

The accretion of bodies in the asteroid belt was halted nearly 4.6 billion years ago by the gravitational influence of the newly formed giant planet Jupiter. The asteroid belt therefore preserves a record of both this earliest epoch of Solar System formation and variation of conditions within the solar nebula. Spectral features in reflected sunlight indicate that some asteroids have experienced sufficient thermal evolution to differentiate into layered structures. The second most massive asteroid--4 Vesta--has differentiated to a crust, mantle and core. 1 Ceres, the largest and most massive asteroid, has in contrast been presumed to be homogeneous, in part because of its low density, low albedo and relatively featureless visible reflectance spectrum, similar to carbonaceous meteorites that have suffered minimal thermal processing. Here we show that Ceres has a shape and smoothness indicative of a gravitationally relaxed object. Its shape is significantly less flattened than that expected for a homogeneous object, but is consistent with a central mass concentration indicative of differentiation. Possible interior configurations include water-ice-rich mantles over a rocky core.

Preliminary Geophysical Survey for Assessing the Geotechnical Conditions and Geohazards at Huaca de La Luna, Peru

NASA Astrophysics Data System (ADS)

Zavala, G. J.; Lopez, S.; Ebinger, C. J.; Pando, M. A.; Lambert, C.; Morales, R.; Uceda, S.; Perucchio, R.; Castaneda, B.; Aguilar, R.

2014-12-01

This paper presents results of near surface geophysical tests to help assess the geotechnical conditions of the archaeological complex of Huaca de la Luna located near the coastal city of Trujillo, Peru. This area of Peru has experienced damaging earthquakes and tsunamis in historic time. The huaca complex is a massive adobe temple progressively built by the Moche civilization from 100 AD to 650 AD. The geophysical tests carried out included Ground Penetrating Radar (GPR), magnetic gradiometer, and Multichannel Analysis of Surface Waves (MASW) to help assess geotechnical conditions such as buried cavities and hallways, thickness and elastic properties of sand sediments, and the depth to the underlying granitic bedrock. The tests were performed to help with the investigation of structural damage observed along a massive adobe wall (north façade) which has shown signs of distress including fissures, settlements, and other damage. The geophysical results together with detailed Lidar surveying are being used as part of this investigation and highlight the usefulness of these non-destructive techniques for archaeological and historical sites.

Rare case of massive congenital bilateral chylothorax in a hydropic fetus with true mosaicism 47,XXX/46,XX.

PubMed

Cremonini, Giorgio; Poggi, Alice; Capucci, Roberta; Vesce, Fortunato; Patella, Alfredo; Marci, Roberto

2014-01-01

Fetal congenital chylothorax is a rare condition that occurs sporadically or can be associated with abnormal karyotype or structural chromosomal anomalies. We report a unique case of fetal congenital bilateral chylothorax associated with mosaicism 47,XXX/46,XX. A female fetus affected by massive bilateral hydrothorax and ascites was diagnosed at 34(+1) weeks of gestation. Previous ultrasonographic exams were completely normal. Immune causes of hydrops were excluded. Elective cesarean section was performed soon after bilateral thoracocentesis. The analysis of drained pleural fluid revealed its lymphatic nature. The fetal karyotyping, performed on chorionic villi at the 11th week, had shown mosaicism 47,XXX/46,XX, later confirmed in the newborn's blood. We hypothesized that chylothorax may be part of the phenotypic spectrum of 47 XXX karyotype and we suggest an ultrasound follow-up of the fetus at closer intervals than the routine timing for this condition, even if it is not usually characterized by severe phenotypic features. © 2013 The Authors. Journal of Obstetrics and Gynaecology Research © 2013 Japan Society of Obstetrics and Gynecology.

Probing the mass assembly of massive nearby galaxies with deep imaging

NASA Astrophysics Data System (ADS)

Duc, P.-A.; Cuillandre, J.-C.; Alatalo, K.; Blitz, L.; Bois, M.; Bournaud, F.; Bureau, M.; Cappellari, M.; Côté, P.; Davies, R. L.; Davis, T. A.; de Zeeuw, P. T.; Emsellem, E.; Ferrarese, L.; Ferriere, E.; Gwyn, S.; Khochfar, S.; Krajnovic, D.; Kuntschner, H.; Lablanche, P.-Y.; McDermid, R. M.; Michel-Dansac, L.; Morganti, R.; Naab, T.; Oosterloo, T.; Sarzi, M.; Scott, N.; Serra, P.; Weijmans, A.; Young, L. M.

2013-07-01

According to a popular scenario supported by numerical models, the mass assembly and growth of massive galaxies, in particular the Early-Type Galaxies (ETGs), is, below a redshift of 1, mainly due to the accretion of multiple gas-poor satellites. In order to get observational evidence of the role played by minor dry mergers, we are obtaining extremely deep optical images of a complete volume limited sample of nearby ETGs. These observations, done with the CFHT as part of the ATLAS3D, NGVS and MATLAS projects, reach a stunning 28.5 - 29 mag.arcsec-2 surface brightness limit in the g' band. They allow us to detect the relics of past collisions such as faint stellar tidal tails as well as the very extended stellar halos which keep the memory of the last episodes of galactic accretion. Images and preliminary results from this on-going survey are presented, in particular a possible correlation between the fine structure index (which parametrizes the amount of tidal perturbation) of the ETGs, their stellar mass, effective radius and gas content.

Hamiltonian structure of three-dimensional gravity in Vielbein formalism

NASA Astrophysics Data System (ADS)

Hajihashemi, Mahdi; Shirzad, Ahmad

2018-01-01

Considering Chern-Simons like gravity theories in three dimensions as first order systems, we analyze the Hamiltonian structure of three theories Topological massive gravity, New massive gravity, and Zwei-Dreibein Gravity. We show that these systems demonstrate a new feature of the constrained systems in which a new kind of constraints emerge due to factorization of determinant of the matrix of Poisson brackets of constraints. We find the desired number of degrees of freedom as well as the generating functional of local Lorentz transformations and diffeomorphism through canonical structure of the system. We also compare the Hamiltonian structure of linearized version of the considered models with the original ones.

Wiggly tails: A gravitational wave signature of massive fields around black holes

NASA Astrophysics Data System (ADS)

Degollado, Juan Carlos; Herdeiro, Carlos A. R.

2014-09-01

Massive fields can exist in long-lived configurations around black holes. We examine how the gravitational wave signal of a perturbed black hole is affected by such "dirtiness" within linear theory. As a concrete example, we consider the gravitational radiation emitted by the infall of a massive scalar field into a Schwarzschild black hole. Whereas part of the scalar field is absorbed/scattered by the black hole and triggers gravitational wave emission, another part lingers in long-lived quasibound states. Solving numerically the Teukolsky master equation for gravitational perturbations coupled to the massive Klein-Gordon equation, we find a characteristic gravitational wave signal, composed by a quasinormal ringing followed by a late time tail. In contrast to "clean" black holes, however, the late time tail contains small amplitude wiggles with the frequency of the dominating quasibound state. Additionally, an observer dependent beating pattern may also be seen. These features were already observed in fully nonlinear studies; our analysis shows they are present at linear level, and, since it reduces to a 1+1 dimensional numerical problem, allows for cleaner numerical data. Moreover, we discuss the power law of the tail and that it only becomes universal sufficiently far away from the dirty black hole. The wiggly tails, by constrast, are a generic feature that may be used as a smoking gun for the presence of massive fields around black holes, either as a linear cloud or as fully nonlinear hair.

Bridging the gap: from massive stars to supernovae

PubMed Central

Crowther, Paul A.; Janka, Hans-Thomas; Langer, Norbert

2017-01-01

Almost since the beginning, massive stars and their resultant supernovae have played a crucial role in the Universe. These objects produce tremendous amounts of energy and new, heavy elements that enrich galaxies, encourage new stars to form and sculpt the shapes of galaxies that we see today. The end of millions of years of massive star evolution and the beginning of hundreds or thousands of years of supernova evolution are separated by a matter of a few seconds, in which some of the most extreme physics found in the Universe causes the explosive and terminal disruption of the star. Key questions remain unanswered in both the studies of how massive stars evolve and the behaviour of supernovae, and it appears the solutions may not lie on just one side of the explosion or the other or in just the domain of the stellar evolution or the supernova astrophysics communities. The need to view massive star evolution and supernovae as continuous phases in a single narrative motivated the Theo Murphy international scientific meeting ‘Bridging the gap: from massive stars to supernovae’ at Chicheley Hall, UK, in June 2016, with the specific purpose of simultaneously addressing the scientific connections between theoretical and observational studies of massive stars and their supernovae, through engaging astronomers from both communities. This article is part of the themed issue ‘Bridging the gap: from massive stars to supernovae’. PMID:28923995

Bridging the gap: from massive stars to supernovae.

PubMed

Maund, Justyn R; Crowther, Paul A; Janka, Hans-Thomas; Langer, Norbert

2017-10-28

Almost since the beginning, massive stars and their resultant supernovae have played a crucial role in the Universe. These objects produce tremendous amounts of energy and new, heavy elements that enrich galaxies, encourage new stars to form and sculpt the shapes of galaxies that we see today. The end of millions of years of massive star evolution and the beginning of hundreds or thousands of years of supernova evolution are separated by a matter of a few seconds, in which some of the most extreme physics found in the Universe causes the explosive and terminal disruption of the star. Key questions remain unanswered in both the studies of how massive stars evolve and the behaviour of supernovae, and it appears the solutions may not lie on just one side of the explosion or the other or in just the domain of the stellar evolution or the supernova astrophysics communities. The need to view massive star evolution and supernovae as continuous phases in a single narrative motivated the Theo Murphy international scientific meeting 'Bridging the gap: from massive stars to supernovae' at Chicheley Hall, UK, in June 2016, with the specific purpose of simultaneously addressing the scientific connections between theoretical and observational studies of massive stars and their supernovae, through engaging astronomers from both communities.This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'. © 2017 The Author(s).

Predicting the nature of supernova progenitors

NASA Astrophysics Data System (ADS)

Groh, Jose H.

2017-09-01

Stars more massive than about 8 solar masses end their lives as a supernova (SN), an event of fundamental importance Universe-wide. The physical properties of massive stars before the SN event are very uncertain, both from theoretical and observational perspectives. In this article, I briefly review recent efforts to predict the nature of stars before death, in particular, by performing coupled stellar evolution and atmosphere modelling of single stars in the pre-SN stage. These models are able to predict the high-resolution spectrum and broadband photometry, which can then be directly compared with the observations of core-collapse SN progenitors. The predictions for the spectral types of massive stars before death can be surprising. Depending on the initial mass and rotation, single star models indicate that massive stars die as red supergiants, yellow hypergiants, luminous blue variables and Wolf-Rayet stars of the WN and WO subtypes. I finish by assessing the detectability of SN Ibc progenitors. This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'.

Luminous blue variables and the fates of very massive stars

NASA Astrophysics Data System (ADS)

Smith, Nathan

2017-09-01

Luminous blue variables (LBVs) had long been considered massive stars in transition to the Wolf-Rayet (WR) phase, so their identification as progenitors of some peculiar supernovae (SNe) was surprising. More recently, environment statistics of LBVs show that most of them cannot be in transition to the WR phase after all, because LBVs are more isolated than allowed in this scenario. Additionally, the high-mass H shells around luminous SNe IIn require that some very massive stars above 40 M⊙ die without shedding their H envelopes, and the precursor outbursts are a challenge for understanding the final burning sequences leading to core collapse. Recent evidence suggests a clear continuum in pre-SN mass loss from super-luminous SNe IIn, to regular SNe IIn, to SNe II-L and II-P, whereas most stripped-envelope SNe seem to arise from a separate channel of lower-mass binary stars rather than massive WR stars. This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'.

Accretion Signatures on Massive Young Stellar Objects

NASA Astrophysics Data System (ADS)

Navarete, F.; Damineli, A.; Barbosa, C. L.; Blum, R. D.

2015-01-01

We present preliminary results from a survey of molecular H2 (2.12 μm) emission in massive young stellar objects (MYSO) candidates selected from the Red MSX Source survey. We observed 354 MYSO candidates through the H2 S(1) 1-0 transition (2.12 μm) and an adjacent continuum narrow-band filters using the Spartan/SOAR and WIRCam/CFHT cameras. The continuum-subtracted H2 maps were analyzed and extended H2 emission was found in 50% of the sample (178 sources), and 38% of them (66) have polar morphology, suggesting collimated outflows. The polar-like structures are more likely to be driven on radio-quiet sources, indicating that these structures occur during the pre-ultra compact H ii phase. We analyzed the continuum images and found that 54% (191) of the sample displayed extended continuum emission and only ~23% (80) were associated to stellar clusters. The extended continuum emission is correlated to the H2 emission and those sources within stellar clusters does display diffuse H2 emission, which may be due to fluorescent H2 emission. These results support the accretion scenario for massive star formation, since the merging of low-mass stars would not produce jet-like structures. Also, the correlation between jet-like structures and radio-quiet sources indicates that higher inflow rates are required to form massive stars in a typical timescale less than 105 years.

Evolution and Nucleosynthesis of Massive Stars

NASA Astrophysics Data System (ADS)

Meynet, Georges; Maeder, André; Choplin, Arthur; Takahashi, Koh; Ekström, Sylvia; Hirschi, Raphael; Chiappini, Cristina; Eggenberger, Patrick

Massive stars are rapid nuclear reactors that play a key role in injecting new synthesized elements in the interstellar medium. Depending on the strengths of the stellar winds on the efficiency of mixing processes, the masses and the chemical compositions of their ejecta can be dramatically different. In a first part, we describe two types of rotating models differing by the physics involved and discussing various consequences. In a second part, we focus on the impacts of rotation in massive stars at very low metallicity. Various nucleosynthetic signatures pointing towards the need for some extra-mixing in the first generation of stars are presented. This extra-mixing has great chance to be driven by rotation for the following reasons: 1) when the metallicity decreases, the formation of fast rotators seem to be favored; 2) rotational mixing is more efficient at low metallicities; 3) primary nitrogen is produced only at low metallicities a fact that can be well explained by more efficient rotational mixing at low metallicities.

2. South elevation with bases of two massive brick chimneys ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. South elevation with bases of two massive brick chimneys flanking structure at southwest and southeast corners. - Charlestown Navy Yard, Incinerator, Midway along northern boundary of Charlestown Navy Yard, on Little Mystic Channel, near junction of Eighteenth Street & Second Avenue, Boston, Suffolk County, MA

Notes on the KIVA-2 software and chemically reactive fluid mechanics

NASA Astrophysics Data System (ADS)

Holst, M. J.

1992-09-01

Working notes regarding the mechanics of chemically reactive fluids with sprays, and their numerical simulation with the KIVA-2 software are presented. KIVA-2 is a large FORTRAN program developed at Los Alamos National Laboratory for internal combustion engine simulation. It is our hope that these notes summarize some of the necessary background material in fluid mechanics and combustion, explain the numerical methods currently used in KIVA-2 and similar combustion codes, and provide an outline of the overall structure of KIVA-2 as a representative combustion program, in order to aid the researcher in the task of implementing KIVA-2 or a similar combustion code on a massively parallel computer. The notes are organized into three parts as follows. In Part 1, a brief introduction to continuum mechanics, to fluid mechanics, and to the mechanics of chemically reactive fluids with sprays is presented. In Part 2, a close look at the governing equations of KIVA-2 is taken, and the methods employed in the numerical solution of these equations is discussed. Some conclusions are drawn and some observations are made in Part 3.

Waves on the surface of the Orion molecular cloud.

PubMed

Berné, Olivier; Marcelino, Núria; Cernicharo, José

2010-08-19

Massive stars influence their parental molecular cloud, and it has long been suspected that the development of hydrodynamical instabilities can compress or fragment the cloud. Identifying such instabilities has proved difficult. It has been suggested that elongated structures (such as the 'pillars of creation') and other shapes arise because of instabilities, but alternative explanations are available. One key signature of an instability is a wave-like structure in the gas, which has hitherto not been seen. Here we report the presence of 'waves' at the surface of the Orion molecular cloud near where massive stars are forming. The waves seem to be a Kelvin-Helmholtz instability that arises during the expansion of the nebula as gas heated and ionized by massive stars is blown over pre-existing molecular gas.

Winds of Massive Magnetic Stars: Interacting Fields and Flow

NASA Astrophysics Data System (ADS)

Daley-Yates, S.; Stevens, I. R.

2018-01-01

We present results of 3D numerical simulations of magnetically confined, radiatively driven stellar winds of massive stars, conducted using the astrophysical MHD code Pluto, with a focus on understanding the rotational variability of radio and sub-mm emission. Radiative driving is implemented according to the Castor, Abbott and Klein theory of radiatively driven winds. Many magnetic massive stars posses a magnetic axis which is inclined with respect to the rotational axis. This misalignment leads to a complex wind structure as magnetic confinement, centrifugal acceleration and radiative driving act to channel the circumstellar plasma into a warped disk whose observable properties should be apparent in multiple wavelengths. This structure is analysed to calculate free-free thermal radio emission and determine the characteristic intensity maps and radio light curves.

Lyman-α emitters gone missing: the different evolution of the bright and faint populations

NASA Astrophysics Data System (ADS)

Weinberger, Lewis H.; Kulkarni, Girish; Haehnelt, Martin G.; Choudhury, Tirthankar Roy

2018-06-01

We model the transmission of the Lyman-α line through the circum- and intergalactic media around dark matter haloes expected to host Lyman-alpha emitters (LAEs) at z ≥ 5.7, using the high-dynamic-range Sherwood simulations. We find very different CGM environments around more massive haloes (˜1011M⊙) compared to less massive haloes (˜109M⊙) at these redshifts, which can contribute to a different evolution of the Lyα transmission from LAEs within these haloes. Additionally we confirm that part of the differential evolution could result from bright LAEs being more likely to reside in larger ionized regions. We conclude that a combination of the CGM environment and the IGM ionization structure is likely to be responsible for the differential evolution of the bright and faint ends of the LAE luminosity function at z ≥ 6. More generally, we confirm the suggestion that the self-shielded neutral gas in the outskirts of the host halo can strongly attenuate the Lyα emission from high redshift galaxies. We find that this has a stronger effect on the more massive haloes hosting brighter LAEs. The faint-end of the LAE luminosity function is thus a more reliable probe of the average ionization state of the IGM. Comparing our model for LAEs with a range of observational data we find that the favoured reionization histories are our previously advocated `Late' and `Very Late' reionization histories, in which reionization finishes rather rapidly at around z ≃ 6.

Critical N = (1, 1) general massive supergravity

NASA Astrophysics Data System (ADS)

Deger, Nihat Sadik; Moutsopoulos, George; Rosseel, Jan

2018-04-01

In this paper we study the supermultiplet structure of N = (1, 1) General Massive Supergravity at non-critical and critical points of its parameter space. To do this, we first linearize the theory around its maximally supersymmetric AdS3 vacuum and obtain the full linearized Lagrangian including fermionic terms. At generic values, linearized modes can be organized as two massless and 2 massive multiplets where supersymmetry relates them in the standard way. At critical points logarithmic modes appear and we find that in three of such points some of the supersymmetry transformations are non-invertible in logarithmic multiplets. However, in the fourth critical point, there is a massive logarithmic multiplet with invertible supersymmetry transformations.

Discovery of a Galaxy Cluster with a Violently Starbursting Core at z = 2.506

NASA Astrophysics Data System (ADS)

Wang, Tao; Elbaz, David; Daddi, Emanuele; Finoguenov, Alexis; Liu, Daizhong; Schreiber, Corentin; Martín, Sergio; Strazzullo, Veronica; Valentino, Francesco; van der Burg, Remco; Zanella, Anita; Ciesla, Laure; Gobat, Raphael; Le Brun, Amandine; Pannella, Maurilio; Sargent, Mark; Shu, Xinwen; Tan, Qinghua; Cappelluti, Nico; Li, Yanxia

2016-09-01

We report the discovery of a remarkable concentration of massive galaxies with extended X-ray emission at z spec = 2.506, which contains 11 massive (M * ≳ 1011 M ⊙) galaxies in the central 80 kpc region (11.6σ overdensity). We have spectroscopically confirmed 17 member galaxies with 11 from CO and the remaining ones from Hα. The X-ray luminosity, stellar mass content, and velocity dispersion all point to a collapsed, cluster-sized dark matter halo with mass M 200c = 1013.9±0.2 M ⊙, making it the most distant X-ray-detected cluster known to date. Unlike other clusters discovered so far, this structure is dominated by star-forming galaxies (SFGs) in the core with only 2 out of the 11 massive galaxies classified as quiescent. The star formation rate (SFR) in the 80 kpc core reaches ˜3400 M ⊙ yr-1 with a gas depletion time of ˜200 Myr, suggesting that we caught this cluster in rapid build-up of a dense core. The high SFR is driven by both a high abundance of SFGs and a higher starburst fraction (˜25%, compared to 3%-5% in the field). The presence of both a collapsed, cluster-sized halo and a predominant population of massive SFGs suggests that this structure could represent an important transition phase between protoclusters and mature clusters. It provides evidence that the main phase of massive galaxy passivization will take place after galaxies accrete onto the cluster, providing new insights into massive cluster formation at early epochs. The large integrated stellar mass at such high redshift challenges our understanding of massive cluster formation.

DISCOVERY OF A GALAXY CLUSTER WITH A VIOLENTLY STARBURSTING CORE AT z = 2.506

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Tao; Elbaz, David; Daddi, Emanuele

2016-09-01

We report the discovery of a remarkable concentration of massive galaxies with extended X-ray emission at z {sub spec} = 2.506, which contains 11 massive (M {sub *} ≳ 10{sup 11} M {sub ⊙}) galaxies in the central 80 kpc region (11.6 σ overdensity). We have spectroscopically confirmed 17 member galaxies with 11 from CO and the remaining ones from H α . The X-ray luminosity, stellar mass content, and velocity dispersion all point to a collapsed, cluster-sized dark matter halo with mass M {sub 200} {sub c} = 10{sup 13.9±0.2} M {sub ⊙}, making it the most distant X-ray-detectedmore » cluster known to date. Unlike other clusters discovered so far, this structure is dominated by star-forming galaxies (SFGs) in the core with only 2 out of the 11 massive galaxies classified as quiescent. The star formation rate (SFR) in the 80 kpc core reaches ∼3400 M {sub ⊙} yr{sup −1} with a gas depletion time of ∼200 Myr, suggesting that we caught this cluster in rapid build-up of a dense core. The high SFR is driven by both a high abundance of SFGs and a higher starburst fraction (∼25%, compared to 3%–5% in the field). The presence of both a collapsed, cluster-sized halo and a predominant population of massive SFGs suggests that this structure could represent an important transition phase between protoclusters and mature clusters. It provides evidence that the main phase of massive galaxy passivization will take place after galaxies accrete onto the cluster, providing new insights into massive cluster formation at early epochs. The large integrated stellar mass at such high redshift challenges our understanding of massive cluster formation.« less

Molecular Cloud Structures and Massive Star Formation in N159

NASA Astrophysics Data System (ADS)

Nayak, O.; Meixner, M.; Fukui, Y.; Tachihara, K.; Onishi, T.; Saigo, K.; Tokuda, K.; Harada, R.

2018-02-01

The N159 star-forming region is one of the most massive giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC). We show the 12CO, 13CO, CS molecular gas lines observed with ALMA in N159 west (N159W) and N159 east (N159E). We relate the structure of the gas clumps to the properties of 24 massive young stellar objects (YSOs) that include 10 newly identified YSOs based on our search. We use dendrogram analysis to identify properties of the molecular clumps, such as flux, mass, linewidth, size, and virial parameter. We relate the YSO properties to the molecular gas properties. We find that the CS gas clumps have a steeper size–linewidth relation than the 12CO or 13CO gas clumps. This larger slope could potentially occur if the CS gas is tracing shocks. The virial parameters of the 13CO gas clumps in N159W and N159E are low (<1). The threshold for massive star formation in N159W is 501 M ⊙ pc‑2, and the threshold for massive star formation in N159E is 794 M ⊙ pc‑2. We find that 13CO is more photodissociated in N159E than N159W. The most massive YSO in N159E has cleared out a molecular gas hole in its vicinity. All the massive YSO candidates in N159E have a more evolved spectral energy distribution type in comparison to the YSO candidates in N159W. These differences lead us to conclude that the giant molecular cloud complex in N159E is more evolved than the giant molecular cloud complex in N159W.

The evolution of massive stars: bridging the gap in the Local Group

NASA Astrophysics Data System (ADS)

Massey, Philip; Neugent, Kathryn F.; Levesque, Emily M.

2017-09-01

The nearby galaxies of the Local Group can act as our laboratories in helping to bridge the gap between theory and observations. In this review, we will describe the complications of identifying samples of OB stars, yellow and red supergiants, and Wolf-Rayet stars, and what we have so far learned from these studies. This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'.

Cardiac and Pulmonary Cystic Echinococcosis with Massive Obstruction of the Pulmonary Vessel System in a 16 Year Old Girl.

PubMed

Kohlmaier, Benno; Trobisch, Andreas; Pfurtscheller, Klaus; Knez, Igor; Klepetko, Walter; Pilhatsch, Alexander; Schweintzger, Sabrina; Zenz, Werner

2018-04-09

We describe herein the management of a 16-year-old girl with cystic echinococcosis (CE) of the right ventricle and massive obstruction of the pulmonary vessel system by parasitic metastatic dissemination. After resection of the cardiac cyst, pulmonary thromboendarterectomy was performed to remove parts of the obstructive parasitic material. The treatment reduced the elevated pulmonary arterial pressure, improving the patient's overall condition.

A Holistic Perspective on the Dynamics of G035.39-00.33: The Interplay between Gas and Magnetic Fields

NASA Astrophysics Data System (ADS)

Liu, Tie; Li, Pak Shing; Juvela, Mika; Kim, Kee-Tae; Evans, Neal J., II; Di Francesco, James; Liu, Sheng-Yuan; Yuan, Jinghua; Tatematsu, Ken’ichi; Zhang, Qizhou; Ward-Thompson, Derek; Fuller, Gary; Goldsmith, Paul F.; Koch, P. M.; Sanhueza, Patricio; Ristorcelli, I.; Kang, Sung-ju; Chen, Huei-Ru; Hirano, N.; Wu, Yuefang; Sokolov, Vlas; Lee, Chang Won; White, Glenn J.; Wang, Ke; Eden, David; Li, Di; Thompson, Mark; Pattle, Kate M.; Soam, Archana; Nasedkin, Evert; Kim, Jongsoo; Kim, Gwanjeong; Lai, Shih-Ping; Park, Geumsook; Qiu, Keping; Zhang, Chuan-Peng; Alina, Dana; Eswaraiah, Chakali; Falgarone, Edith; Fich, Michel; Greaves, Jane; Gu, Q.-L.; Kwon, Woojin; Li, Hua-bai; Malinen, Johanna; Montier, Ludovic; Parsons, Harriet; Qin, Sheng-Li; Rawlings, Mark G.; Ren, Zhi-Yuan; Tang, Mengyao; Tang, Y.-W.; Toth, L. V.; Wang, Jiawei; Wouterloot, Jan; Yi, H.-W.; Zhang, H.-W.

2018-06-01

Magnetic field plays a crucial role in shaping molecular clouds and regulating star formation, yet the complete information on the magnetic field is not well constrained owing to the limitations in observations. We study the magnetic field in the massive infrared dark cloud G035.39-00.33 from dust continuum polarization observations at 850 μm with SCUBA-2/POL-2 at JCMT for the first time. The magnetic field tends to be perpendicular to the densest part of the main filament (F M), whereas it has a less defined relative orientation in the rest of the structure, where it tends to be parallel to some diffuse regions. A mean plane-of-the-sky magnetic field strength of ∼50 μG for F M is obtained using the Davis–Chandrasekhar–Fermi method. Based on 13CO (1–0) line observations, we suggest a formation scenario of F M due to large-scale (∼10 pc) cloud–cloud collision. Using additional NH3 line data, we estimate that F M will be gravitationally unstable if it is only supported by thermal pressure and turbulence. The northern part of F M, however, can be stabilized by a modest additional support from the local magnetic field. The middle and southern parts of F M are likely unstable even if the magnetic field support is taken into account. We claim that the clumps in F M may be supported by turbulence and magnetic fields against gravitational collapse. Finally, we identified for the first time a massive (∼200 M ⊙), collapsing starless clump candidate, “c8,” in G035.39-00.33. The magnetic field surrounding “c8” is likely pinched, hinting at an accretion flow along the filament.

A Bootstrap Approach to Martian Manufacturing

NASA Technical Reports Server (NTRS)

Dorais, Gregory A.

2004-01-01

In-Situ Resource Utilization (ISRU) is an essential element of any affordable strategy for a sustained human presence on Mars. Ideally, Martian habitats would be extremely massive to allow plenty of room to comfortably live and work, as well as to protect the occupants from the environment. Moreover, transportation and power generation systems would also require significant mass if affordable. For our approach to ISRU, we use the industrialization of the U.S. as a metaphor. The 19th century started with small blacksmith shops and ended with massive steel mills primarily accomplished by blacksmiths increasing their production capacity and product size to create larger shops, which produced small mills, which produced the large steel mills that industrialized the country. Most of the mass of a steel mill is comprised of steel in simple shapes, which are produced and repaired with few pieces of equipment also mostly made of steel in basic shapes. Due to this simplicity, we expect that the 19th century manufacturing growth can be repeated on Mars in the 21st century using robots as the primary labor force. We suggest a "bootstrap" approach to manufacturing on Mars that uses a "seed" manufacturing system that uses regolith to create major structural components and spare parts. The regolith would be melted, foamed, and sintered as needed to fabricate parts using casting and solid freeform fabrication techniques. Complex components, such as electronics, would be brought from Earth and integrated as needed. These parts would be assembled to create additional manufacturing systems, which can be both more capable and higher capacity. These subsequent manufacturing systems could refine vast amounts of raw materials to create large components, as well as assemble equipment, habitats, pressure vessels, cranes, pipelines, railways, trains, power generation stations, and other facilities needed to economically maintain a sustained human presence on Mars.

Tourmaline in Appalachian - Caledonian massive sulphide deposits and its exploration significance.

USGS Publications Warehouse

Slack, J.F.

1982-01-01

Tourmaline is a common gangue mineral in several types of stratabound mineral deposits, including some massive base-metal sulphide ores of the Appalachian - Caledonian orogen. It is most abundant (sometimes forming massive foliated tourmalinite) in sediment-hosted deposits, such as those at the Elizabeth Cu mine and the Ore Knob Cu mine (North Carolina, USA). Trace amounts of tourmaline occur associated with volcanic-hosted deposits in the Piedmont and New England and also in the Trondheim district. Tourmaline associated with the massive sulphide deposits are Mg- rich dravites with major- and trace-element compositions significantly different from schorl. It is suggested that the necessary B was produced by submarine exhalative processes as a part of the same hydrothermal system that deposited the ores. An abundance of dravite in non-evaporitic terrains is believed to indicate proximity to former subaqueous fumarolic centres.-R.A.H.

The assembly of stellar haloes in massive Early-Type Galaxies

NASA Astrophysics Data System (ADS)

Buitrago, F.

2017-03-01

Massive (Mstellar >= 5×1010 M⊙) Early-Type Galaxies (ETGs) must build an outer stellar envelope over cosmic time in order to account for their remarkable size evolution. This is similar to what occurs to nearby Late-Type Galaxies (LTGs), which create their stellar haloes out of the debris of lower mass systems. We analysed the outer parts of massive ETGs at z < 1 by exploiting the Hubble Ultra Deep Field imaging. These galaxies store 10-30% of their stellar mass at distances 10 < R/kpc < 50, in contrast to the low percentages (< 5%) found for LTGs. We find evidence for a progressive outskirt development with redshift driven solely via merging.

The massive stellar population of W49: A spectroscopic survey

NASA Astrophysics Data System (ADS)

Wu, Shi-Wei; Bik, Arjan; Bestenlehner, Joachim M.; Henning, Thomas; Pasquali, Anna; Brandner, Wolfgang; Stolte, Andrea

2016-05-01

Context. Massive stars form on different scales that range from large, dispersed OB associations to compact, dense starburst clusters. The complex structure of regions of massive star formation and the involved short timescales provide a challenge for our understanding of their birth and early evolution. As one of the most massive and luminous star-forming region in our Galaxy, W49 is the ideal place to study the formation of the most massive stars. Aims: By classifying the massive young stars that are deeply embedded in the molecular cloud of W49, we aim to investigate and trace the star formation history of this region. Methods: We analyse near-infrared K-band spectroscopic observations of W49 from LBT/LUCI combined with JHK images obtained with NTT/SOFI and LBT/LUCI. Based on JHK-band photometry and K-band spectroscopy, the massive stars are placed in a Hertzsprung Russell diagram. By comparison with evolutionary models, their age and hence the star formation history of W49 can be investigated. Results: Fourteen O-type stars, as well as two young stellar objects (YSOs), are identified by our spectroscopic survey. Eleven O stars are main sequence stars with subtypes ranging from O3 to O9.5 and masses ranging from ~20 M⊙ to ~120 M⊙. Three of the O stars show strong wind features and are considered to be Of-type supergiants with masses beyond 100 M⊙. The two YSOs show CO emission, which is indicative of the presence of circumstellar disks in the central region of the massive cluster. The age of the cluster is estimated as ~1.5 Myr, with star formation continuing in different parts of the region. The ionising photons from the central massive stars have not yet cleared the molecular cocoon surrounding the cluster. W49 is comparable to extragalactic star-forming regions, and it provides us with a unique chance to study a starburst in detail. Based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in Germany, Italy and the United States. LBT Corporation partners are: LBT Beteiligungsgesellschaft, Germany, representing the Max Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; Istituto Nazionale di Astrofisica, Italy; The University of Arizona on behalf of the Arizona university system; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia.Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 67.C-0514 and 073.D-0837.The reduced spectra (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/589/A16

Characteristics of Massive Open Online Courses (MOOCs): A Research Review, 2009-2012

ERIC Educational Resources Information Center

Kennedy, Jolie

2014-01-01

This review of research explores characteristics associated with massive open online courses (MOOCs). Three key characteristics are revealed: varied definitions of openness, barriers to persistence, and a distinct structure that takes the form as one of two pedagogical approaches. The concept of openness shifts among different MOOCs, models,…

A Taxonomy of Massive Open Online Courses

ERIC Educational Resources Information Center

Pilli, Olga; Admiraal, Wilfried

2016-01-01

Massive Open Online Courses (MOOCs) as a new approach to distance education, which originated from the open education resources (OER) movement, are becoming widespread throughout the world. Over time, early versions of cMOOCs have undergone changes in terms of use, name and structure. In their short life, MOOCs have been categorized into different…

Characterizing filaments in regions of high-mass star formation: High-resolution submilimeter imaging of the massive star-forming complex NGC 6334 with ArTéMiS

NASA Astrophysics Data System (ADS)

André, Ph.; Revéret, V.; Könyves, V.; Arzoumanian, D.; Tigé, J.; Gallais, P.; Roussel, H.; Le Pennec, J.; Rodriguez, L.; Doumayrou, E.; Dubreuil, D.; Lortholary, M.; Martignac, J.; Talvard, M.; Delisle, C.; Visticot, F.; Dumaye, L.; De Breuck, C.; Shimajiri, Y.; Motte, F.; Bontemps, S.; Hennemann, M.; Zavagno, A.; Russeil, D.; Schneider, N.; Palmeirim, P.; Peretto, N.; Hill, T.; Minier, V.; Roy, A.; Rygl, K. L. J.

2016-07-01

Context. Herschel observations of nearby molecular clouds suggest that interstellar filaments and prestellar cores represent two fundamental steps in the star formation process. The observations support a picture of low-mass star formation according to which filaments of ~0.1 pc width form first in the cold interstellar medium, probably as a result of large-scale compression of interstellar matter by supersonic turbulent flows, and then prestellar cores arise from gravitational fragmentation of the densest filaments. Whether this scenario also applies to regions of high-mass star formation is an open question, in part because the resolution of Herschel is insufficient to resolve the inner width of filaments in the nearest regions of massive star formation. Aims: In an effort to characterize the inner width of filaments in high-mass star-forming regions, we imaged the central part of the NGC 6334 complex at a resolution higher by a factor of >3 than Herschel at 350 μm. Methods: We used the large-format bolometer camera ArTéMiS on the APEX telescope and combined the high-resolution ArTéMiS data at 350 μm with Herschel/HOBYS data at 70-500 μm to ensure good sensitivity to a broad range of spatial scales. This allowed us to study the structure of the main narrow filament of the complex with a resolution of 8″ or <0.07 pc at d ~ 1.7 kpc. Results: Our study confirms that this filament is a very dense, massive linear structure with a line mass ranging from ~500 M⊙/pc to ~2000 M⊙/pc over nearly 10 pc. It also demonstrates for the first time that its inner width remains as narrow as W ~ 0.15 ± 0.05 pc all along the filament length, within a factor of <2 of the characteristic 0.1 pc value found with Herschel for lower-mass filaments in the Gould Belt. Conclusions: While it is not completely clear whether the NGC 6334 filament will form massive stars in the future, it is two to three orders of magnitude denser than the majority of filaments observed in Gould Belt clouds, and has a very similar inner width. This points to a common physical mechanism for setting the filament width and suggests that some important structural properties of nearby clouds also hold in high-mass star-forming regions. This publication is based on data acquired with the Atacama Pathfinder Experiment (APEX) in ESO program 091.C-0870. APEX is a collaboration between the Max-Planck-Institut für Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory.The final ArTéMiS+SPIRE 350 μm map (Fig. 1b) is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A54

Massive QCD Amplitudes at Higher Orders

NASA Astrophysics Data System (ADS)

Moch, S.; Mitov, A.

2007-11-01

We consider the factorisation properties of on-shell QCD amplitudes with massive partons in the limit when all kinematical invariants are large compared to the parton mass and discuss the structure of their infrared singularities. The dimensionally regulated soft poles and the large collinear logarithms of the parton masses exponentiate to all orders. Based on this factorisation a simple relation between massless and massive scattering amplitudes in gauge theories can be established. We present recent applications of this relation for the calculation of the two-loop virtual QCD corrections to the hadro-production of heavy quarks.

Growth histories in bimetric massive gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berg, Marcus; Buchberger, Igor; Enander, Jonas

2012-12-01

We perform cosmological perturbation theory in Hassan-Rosen bimetric gravity for general homogeneous and isotropic backgrounds. In the de Sitter approximation, we obtain decoupled sets of massless and massive scalar gravitational fluctuations. Matter perturbations then evolve like in Einstein gravity. We perturb the future de Sitter regime by the ratio of matter to dark energy, producing quasi-de Sitter space. In this more general setting the massive and massless fluctuations mix. We argue that in the quasi-de Sitter regime, the growth of structure in bimetric gravity differs from that of Einstein gravity.

A BUTTERFLY-SHAPED 'PAPILLON' NEBULA YIELDS SECRETS OF MASSIVE STAR BIRTH

NASA Technical Reports Server (NTRS)

2002-01-01

A NASA Hubble Space Telescope view of a turbulent cauldron of starbirth, called N159, taking place 170,000 light-years away in our satellite galaxy, the Large Magellanic Cloud (LMC). Torrential stellar winds from hot newborn massive stars within the nebula sculpt ridges, arcs, and filaments in the vast cloud, which is over 150 light-years across. A rare type of compact ionized 'blob' is resolved for the first time to be a butterfly-shaped or 'Papillon' (French for 'butterfly') nebula, buried in the center of the maelstrom of glowing gases and dark dust. The unprecedented details of the structure of the Papillon, itself less than 2 light-years in size (about 2 arcseconds in the sky), are seen in the inset. A possible explanation of this bipolar shape is the outflow of gas from massive stars (over 10 times the mass of our sun) hidden in the central absorption zone. Such stars are so hot that their radiation pressure halts the infall of gas and directs it away from the stars in two opposite directions. Presumably, a dense equatorial disk formed by matter still trying to fall in onto the stars focuses the outstreaming matter into the bipolar directions. This observation is part of a search for young massive stars in the LMC. Rare are the cases where we can see massive stars so early after their birth. The red in this true-color image is from the emission of hydrogen and the yellow from high excitation ionized oxygen. The picture was taken on September 5, 1998 with the Wide Field Planetary Camera 2. The Hubble observations of the Papillon nebula were conducted by the European astronomers Mohammad Heydari-Malayeri (Paris Observatory, France) and co-investigators Michael Rosa (Space Telescope-European Coordinating Facility, European Southern Observatory, Germany), Vassilis Charmandaris (Paris Observatory), Lise Deharveng (Marseille Observatory, France), and Hans Zinnecker (Astrophysical Institute, Potsdam, Germany). Their work is submitted for publication in the European journal Astronomy and Astrophysics. Credit: M. Heydari-Malayeri (Paris Observatory) and NASA/ESA

Luminous blue variables and the fates of very massive stars.

PubMed

Smith, Nathan

2017-10-28

Luminous blue variables (LBVs) had long been considered massive stars in transition to the Wolf-Rayet (WR) phase, so their identification as progenitors of some peculiar supernovae (SNe) was surprising. More recently, environment statistics of LBVs show that most of them cannot be in transition to the WR phase after all, because LBVs are more isolated than allowed in this scenario. Additionally, the high-mass H shells around luminous SNe IIn require that some very massive stars above 40  M ⊙ die without shedding their H envelopes, and the precursor outbursts are a challenge for understanding the final burning sequences leading to core collapse. Recent evidence suggests a clear continuum in pre-SN mass loss from super-luminous SNe IIn, to regular SNe IIn, to SNe II-L and II-P, whereas most stripped-envelope SNe seem to arise from a separate channel of lower-mass binary stars rather than massive WR stars.This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'. © 2017 The Author(s).

Predicting the nature of supernova progenitors.

PubMed

Groh, Jose H

2017-10-28

Stars more massive than about 8 solar masses end their lives as a supernova (SN), an event of fundamental importance Universe-wide. The physical properties of massive stars before the SN event are very uncertain, both from theoretical and observational perspectives. In this article, I briefly review recent efforts to predict the nature of stars before death, in particular, by performing coupled stellar evolution and atmosphere modelling of single stars in the pre-SN stage. These models are able to predict the high-resolution spectrum and broadband photometry, which can then be directly compared with the observations of core-collapse SN progenitors. The predictions for the spectral types of massive stars before death can be surprising. Depending on the initial mass and rotation, single star models indicate that massive stars die as red supergiants, yellow hypergiants, luminous blue variables and Wolf-Rayet stars of the WN and WO subtypes. I finish by assessing the detectability of SN Ibc progenitors.This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'. © 2017 The Author(s).

Ways to improve the technology of constructing concrete hydraulic structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osipov, A.D.

1985-05-01

The authors state that there is a need for a critical analysis of the established technology of constructing massive concrete structures and for the search for new, cheap, faster, and less labor-intensive designs when constructing concrete dams. Improvement of the technology of constructing concrete hydraulic structures is possible, they say, by introducing the following suggestions: construction of massive structures mainly from a very stiff, low-cement concrete mix compacted by the vibrating roller method; use of poured self-compacting concrete mixes when constructing reinforced-concrete structural elements of hydrostations, water intakes, tunnel linings, etc.; and by development of the technology of delivering stiffmore » concrete mixes by conveyors and their placement by rotary throwers when revetting slopes. This paper examines these elements in detail.« less

Substorm wave base felsic hydroclastic deposits in the Archean Lac des Vents volcanic complex, Abitibi belt, Canada

NASA Astrophysics Data System (ADS)

Mueller, Wulf; Chown, E. H.; Potvin, Robin

1994-05-01

Volcaniclastic deposits of the 2.3-km-thick Archean Lac des Vents volcanic complex are an integral part of major submarine volcanic construction. The volcanic edifice, which formed on a subaqueous basalt plain, is comparable to modern seamounts resting on the ocean floor. The initial 770 m of the mafic-felsic edifice, subject of this study, is composed of massive, brecciated and pillowed basalts, massive to brecciated felsic lava flows and abundant felsic fragmental rocks of hydroclastic origin. Four distinct volcaniclastic lithofacies constitute the latter: (1) the pumice lapilli-tuff lithofacies; (2) the lapilli-tuff breccia lithofacies characterized by two sublithofacies; (3) the turbidite tuff and tuff-breccia lithofacies; and (4) the volcanic sandstone and breccia lithofacies. These four volcaniclastic lithofacies are considered to be the result of explosive and non-explosive hydrovolcanic fragmentation processes operating at depths below storm wave base (> 200 m). Primary deposition or limited remobilization of unconsolidated hydroclastic debris is shown by the preservation of delicate clasts and volcanic textures, and heat retention structures. The principal transport agents are high-concentration sediment gravity flows occurring under laminar and turbulent flow conditions. High- and low-density turbiditic tuffs and fine-grained tuff fallout deposits, are related to either the dissipating stages of volcanic eruptions or slumping of syneruptive volcanic debris on the flanks of a subaqueous volcanic edifice. Ubiquitous interstratification of volcaniclastic turbidites, shale, and pillowed basalt flows with the felsic lava flows and fragmental debris favours subaqueous deposition. These features combined with the absence of wave-induced sedimentary structures, imply deposition in water depths in excess of 200 m. Viscous feldspar-phyric massive and brecciated felsic flows, and associated volcaniclastics cross cut by felsic dykes, suggest vent proximity. The abundance of breccia-size hydroclastic debris is consistent with this interpretation. Collectively, these criteria argue for subaqueous fragmentation and deposition of volcaniclastics of inferred hydroclastic origin close to the central vent area at depths below storm wave base.

UV TO FAR-IR CATALOG OF A GALAXY SAMPLE IN NEARBY CLUSTERS: SPECTRAL ENERGY DISTRIBUTIONS AND ENVIRONMENTAL TRENDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernandez-Fernandez, Jonathan D.; Iglesias-Paramo, J.; Vilchez, J. M., E-mail: jonatan@iaa.es

2012-03-01

In this paper, we present a sample of cluster galaxies devoted to study the environmental influence on the star formation activity. This sample of galaxies inhabits in clusters showing a rich variety in their characteristics and have been observed by the SDSS-DR6 down to M{sub B} {approx} -18, and by the Galaxy Evolution Explorer AIS throughout sky regions corresponding to several megaparsecs. We assign the broadband and emission-line fluxes from ultraviolet to far-infrared to each galaxy performing an accurate spectral energy distribution for spectral fitting analysis. The clusters follow the general X-ray luminosity versus velocity dispersion trend of L{sub X}more » {proportional_to} {sigma}{sup 4.4}{sub c}. The analysis of the distributions of galaxy density counting up to the 5th nearest neighbor {Sigma}{sub 5} shows: (1) the virial regions and the cluster outskirts share a common range in the high density part of the distribution. This can be attributed to the presence of massive galaxy structures in the surroundings of virial regions. (2) The virial regions of massive clusters ({sigma}{sub c} > 550 km s{sup -1}) present a {Sigma}{sub 5} distribution statistically distinguishable ({approx}96%) from the corresponding distribution of low-mass clusters ({sigma}{sub c} < 550 km s{sup -1}). Both massive and low-mass clusters follow a similar density-radius trend, but the low-mass clusters avoid the high density extreme. We illustrate, with ABELL 1185, the environmental trends of galaxy populations. Maps of sky projected galaxy density show how low-luminosity star-forming galaxies appear distributed along more spread structures than their giant counterparts, whereas low-luminosity passive galaxies avoid the low-density environment. Giant passive and star-forming galaxies share rather similar sky regions with passive galaxies exhibiting more concentrated distributions.« less

Neotectonics of the Vajont dam site

NASA Astrophysics Data System (ADS)

Mantovani, Franco; Vita-Finzi, Claudio

2003-08-01

The disastrous Vajont landslide (NE Italy) of 9 October 1963 is generally thought to have occurred on an existing failure surface. Reassessment of the morphological and structural evidence suggests that movement was on a normal fault plane which had juxtaposed Cretaceous limestone and highly fractured rock debris, thus rendering the dam site unusually susceptible to massive sliding. The proposed fault is consistent in strike with the regional lineament pattern. Although movement was triggered by the combined effects of heavy rainfall and changes in reservoir level, there is circumstantial evidence that seismicity played a contributory part in mobilising the slide by increasing pore pressure at the base of the slide as well as by any associated shaking.

Two phase formation of massive elliptical galaxies: study through cross-correlation including spatial effect

NASA Astrophysics Data System (ADS)

Modak, Soumita; Chattopadhyay, Tanuka; Chattopadhyay, Asis Kumar

2017-11-01

Area of study is the formation mechanism of the present-day population of elliptical galaxies, in the context of hierarchical cosmological models accompanied by accretion and minor mergers. The present work investigates the formation and evolution of several components of the nearby massive early-type galaxies (ETGs) through cross-correlation function (CCF), using the spatial parameters right ascension (RA) and declination (DEC), and the intrinsic parameters mass (M_{*}) and size. According to the astrophysical terminology, here these variables, namely mass, size, RA and DEC are termed as parameters, whereas the unknown constants involved in the kernel function are called hyperparameters. Throughout this paper, the parameter size is used to represent the effective radius (Re). Following Huang et al. (2013a), each nearby ETG is divided into three parts on the basis of its Re value. We study the CCF between each of these three components of nearby massive ETGs and the ETGs in the high redshift range, 0.5< z≤ 2.7. It is found that the innermost components of nearby ETGs are highly correlated with ETGs in the redshift range, 2< z≤ 2.7, known as `red nuggets'. The intermediate and the outermost parts have moderate correlations with ETGs in the redshift range, 0.5< z≤ 0.75. The quantitative measures are highly consistent with the two phase formation scenario of nearby massive ETGs, as suggested by various authors, and resolve the conflict raised in a previous work (De et al. 2014) suggesting other possibilities for the formation of the outermost part. A probable cause of this improvement is the inclusion of the spatial effects in addition to the other parameters in the study.

MASGOMAS PROJECT, New automatic-tool for cluster search on IR photometric surveys

NASA Astrophysics Data System (ADS)

Rübke, K.; Herrero, A.; Borissova, J.; Ramirez-Alegria, S.; García, M.; Marin-Franch, A.

2015-05-01

The Milky Way is expected to contain a large number of young massive (few x 1000 solar masses) stellar clusters, borne in dense cores of gas and dust. Yet, their known number remains small. We have started a programme to search for such clusters, MASGOMAS (MAssive Stars in Galactic Obscured MAssive clusterS). Initially, we selected promising candidates by means of visual inspection of infrared images. In a second phase of the project we have presented a semi-automatic method to search for obscured massive clusters that resulted in the identification of new massive clusters, like MASGOMAS-1 (with more than 10,000 solar masses) and MASGOMAS-4 (a double-cored association of about 3,000 solar masses). We have now developped a new automatic tool for MASGOMAS that allows the identification of a large number of massive cluster candidates from the 2MASS and VVV catalogues. Cluster candidates fulfilling criteria appropriated for massive OB stars are thus selected in an efficient and objective way. We present the results from this tool and the observations of the first selected cluster, and discuss the implications for the Milky Way structure.

The evolution of massive stars: bridging the gap in the Local Group.

PubMed

Massey, Philip; Neugent, Kathryn F; Levesque, Emily M

2017-10-28

The nearby galaxies of the Local Group can act as our laboratories in helping to bridge the gap between theory and observations. In this review, we will describe the complications of identifying samples of OB stars, yellow and red supergiants, and Wolf-Rayet stars, and what we have so far learned from these studies.This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'. © 2017 The Author(s).

An Exploration of Friendships and Socialization for Adolescents with Autism Engaged in Massively Multiplayer Online Role-Playing Games (MMORPG)

ERIC Educational Resources Information Center

Gallup, Jennifer; Duff, Christine; Serianni, Barbara; Gallup, Adam

2016-01-01

A phenomenological study was conducted to investigate the social experiences and perceptions of friendship among three adolescents with an Autism Spectrum Disorder (ASD) engaged in online videogame play in the context of a massively multiplayer online role-playing game (MMORPG). Semi-structured interviews with three participants, diagnosed with…

Cryofacial Analysis of Permafrost Soils

NASA Astrophysics Data System (ADS)

Shur, Y.; Kanevskiy, M.; Jorgenson, M. T.; Fortier, D.

2008-12-01

Cryogenic structure of soils, specifically the patterns formed by ice inclusions and massive ice in permafrost, depends on the genesis of soils and the way they are transformed into a perennially frozen state. Katasonov (1963) recognized that the analysis of relationship between the patterns of cryogenic structure and the processes of permafrost formation (he termed 'cryofacial analysis') is a powerful tool for understanding of genesis of permafrost in relation to different sediment types. He applied cryofacial analysis to Late Pleistocene syngenetic permafrost (yedoma) and to permafrost formed during freezing of thaw bulbs under drained lakes in the continuous permafrost zone. Our long-term studies of cryogenic structure in Alaska and Russia found that cryofacial analysis can be applied to all types of permafrost soil. We described the evolution of cryogenic structure associated with alluvial chronosequences on arctic floodplains in Russia and Alaska and found the differing cryofacies are highly related to patterns of ecosystem development. Cryogenic structure of glacial-lacustrine deposits in several parts of Alaska is similar to cryogenic structure of these deposits in differing permafrost areas in Russia. Cryofacial analysis is extremely useful in recognition of later modifications of permafrost when compared soils are identical in composition. For example, we differentiated original syngenetic permafrost from permafrost modified by thermokarst and thermal erosion in the CRREL permafrost tunnel at Fox, Alaska on the basis of differences in cryogenic structure. We identified unique cryogenic structures associated with the transient zone of the upper permafrost and with the formation of thermokarst-cave ice. Cryofacial analysis showed that parts of permafrost which were previously thawed after fire can be easily distinguished from parts unaffected by thawing. Cryofacial analysis helped in recognizing areas in central and northern Alaska unaffected by the last glaciation. Finally, the study of basal ice under contemporary glaciers makes possible detection of buried glacial ice along the margins of the Arctic Ocean.

Interacting supernovae from photoionization-confined shells around red supergiant stars

NASA Astrophysics Data System (ADS)

Mackey, Jonathan; Mohamed, Shazrene; Gvaramadze, Vasilii V.; Kotak, Rubina; Langer, Norbert; Meyer, Dominique M.-A.; Moriya, Takashi J.; Neilson, Hilding R.

2014-08-01

Betelgeuse, a nearby red supergiant, is a fast-moving star with a powerful stellar wind that drives a bow shock into its surroundings. This picture has been challenged by the discovery of a dense and almost static shell that is three times closer to the star than the bow shock and has been decelerated by some external force. The two physically distinct structures cannot both be formed by the hydrodynamic interaction of the wind with the interstellar medium. Here we report that a model in which Betelgeuse's wind is photoionized by radiation from external sources can explain the static shell without requiring a new understanding of the bow shock. Pressure from the photoionized wind generates a standing shock in the neutral part of the wind and forms an almost static, photoionization-confined shell. Other red supergiants should have much more massive shells than Betelgeuse, because the photoionization-confined shell traps up to 35 per cent of all mass lost during the red supergiant phase, confining this gas close to the star until it explodes. After the supernova explosion, massive shells dramatically affect the supernova light curve, providing a natural explanation for the many supernovae that have signatures of circumstellar interaction.

Interacting supernovae from photoionization-confined shells around red supergiant stars.

PubMed

Mackey, Jonathan; Mohamed, Shazrene; Gvaramadze, Vasilii V; Kotak, Rubina; Langer, Norbert; Meyer, Dominique M-A; Moriya, Takashi J; Neilson, Hilding R

2014-08-21

Betelgeuse, a nearby red supergiant, is a fast-moving star with a powerful stellar wind that drives a bow shock into its surroundings. This picture has been challenged by the discovery of a dense and almost static shell that is three times closer to the star than the bow shock and has been decelerated by some external force. The two physically distinct structures cannot both be formed by the hydrodynamic interaction of the wind with the interstellar medium. Here we report that a model in which Betelgeuse's wind is photoionized by radiation from external sources can explain the static shell without requiring a new understanding of the bow shock. Pressure from the photoionized wind generates a standing shock in the neutral part of the wind and forms an almost static, photoionization-confined shell. Other red supergiants should have much more massive shells than Betelgeuse, because the photoionization-confined shell traps up to 35 per cent of all mass lost during the red supergiant phase, confining this gas close to the star until it explodes. After the supernova explosion, massive shells dramatically affect the supernova light curve, providing a natural explanation for the many supernovae that have signatures of circumstellar interaction.

Topological charges in SL(2,R) covariant massive 11-dimensional and type IIB supergravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Callister, Andrew K.; Smith, Douglas J.

2009-12-15

In this paper we construct closed expressions that correspond to the topological charges of the various 1/2-BPS states of the maximal 10- and 11-dimensional supergravity theories. These expressions are related to the structure of the supersymmetry algebras in curved spacetimes. We mainly focus on IIB supergravity and 11-dimensional supergravity in a double M9-brane background, with an emphasis on the SL(2,R) multiplet structure of the charges and how these map between theories. This includes the charges corresponding to the multiplets of 7- and 9-branes in IIB. We find that examining the possible multiplet structures of the charges provides another tool formore » exploring the spectrum of BPS states that appear in these theories. As a prerequisite to constructing the charges we determine the field equations and multiplet structure of the 11-dimensional gauge potentials, extending previous results on the subject. The massive gauge transformations of the fields are also discussed. We also demonstrate how these massive gauge transformations are compatible with the construction of an SL(2,R) covariant kinetic term in the 11-dimensional Kaluza-Klein monopole worldvolume action.« less

A survey of extended H2 emission from massive YSOs

NASA Astrophysics Data System (ADS)

Navarete, F.; Damineli, A.; Barbosa, C. L.; Blum, R. D.

2015-07-01

We present the results from a survey, designed to investigate the accretion process of massive young stellar objects (MYSOs) through near-infrared narrow-band imaging using the H2 ν=1-0 S(1) transition filter. A sample of 353 MYSO candidates was selected from the Red MSX Source survey using photometric criteria at longer wavelengths (infrared and submillimetre) and chosen with positions throughout the Galactic plane. Our survey was carried out at the Southern Astrophysical Research Telescope Telescope in Chile and Canada-France-Hawaii Telescope in Hawaii covering both hemispheres. The data reveal that extended H2 emission is a good tracer of outflow activity, which is a signpost of accretion process on young massive stars. Almost half of the sample exhibit extended H2 emission and 74 sources (21 per cent) have polar morphology, suggesting collimated outflows. The polar-like structures are more likely to appear on radio-quiet sources, indicating these structures occur during the pre-UCH II phase. We also found an important fraction of sources associated with fluorescent H2 diffuse emission that could be due to a more evolved phase. The images also indicate only ˜23 per cent (80) of the sample is associated with extant (young) stellar clusters. These results support the scenario in which massive stars are formed by accretion discs, since the merging of low-mass stars would not produce outflow structures.

The border effect in surname structure: an Italian-Slovenian case study.

PubMed

Lucchetti, Enzo; Tasso, Miro; Amoruso, Irene; Caravello, Gianumberto

2011-06-01

Population surname structure in northeastern Italy municipalities, in which small Slovenian-speaking groups are present, are compared with neighboring populations of both Italian and Slovenian nationality. In the early 20th century those municipalities were part of the Italian territory and underwent a massive Italianization process that led to the mutation of the original Slovenian surnames into a derived Italian form. In order to track surname relationships among the examined communities, two different similarity analyses were performed: the first using the surnames as they are recorded in the Italian and Slovenian official telephone directories, and the second restoring the Italianized Slovenian surnames to their original form and then recalculating the populations' similarity. Both comparisons evidence a separation that depends on nationality, which is less marked after restoring surnames to their original form. Geographical elements, older historical events, and socioeconomic traits allow interpretation of these results.

MassiveNuS: cosmological massive neutrino simulations

NASA Astrophysics Data System (ADS)

Liu, Jia; Bird, Simeon; Zorrilla Matilla, José Manuel; Hill, J. Colin; Haiman, Zoltán; Madhavacheril, Mathew S.; Petri, Andrea; Spergel, David N.

2018-03-01

The non-zero mass of neutrinos suppresses the growth of cosmic structure on small scales. Since the level of suppression depends on the sum of the masses of the three active neutrino species, the evolution of large-scale structure is a promising tool to constrain the total mass of neutrinos and possibly shed light on the mass hierarchy. In this work, we investigate these effects via a large suite of N-body simulations that include massive neutrinos using an analytic linear-response approximation: the Cosmological Massive Neutrino Simulations (MassiveNuS). The simulations include the effects of radiation on the background expansion, as well as the clustering of neutrinos in response to the nonlinear dark matter evolution. We allow three cosmological parameters to vary: the neutrino mass sum Mν in the range of 0–0.6 eV, the total matter density Ωm, and the primordial power spectrum amplitude As. The rms density fluctuation in spheres of 8 comoving Mpc/h (σ8) is a derived parameter as a result. Our data products include N-body snapshots, halo catalogues, merger trees, ray-traced galaxy lensing convergence maps for four source redshift planes between zs=1–2.5, and ray-traced cosmic microwave background lensing convergence maps. We describe the simulation procedures and code validation in this paper. The data are publicly available at http://columbialensing.org.

The Mass, Color, and Structural Evolution of Today’s Massive Galaxies Since z ˜ 5

NASA Astrophysics Data System (ADS)

Hill, Allison R.; Muzzin, Adam; Franx, Marijn; Clauwens, Bart; Schreiber, Corentin; Marchesini, Danilo; Stefanon, Mauro; Labbe, Ivo; Brammer, Gabriel; Caputi, Karina; Fynbo, Johan; Milvang-Jensen, Bo; Skelton, Rosalind E.; van Dokkum, Pieter; Whitaker, Katherine E.

2017-03-01

In this paper, we use stacking analysis to trace the mass growth, color evolution, and structural evolution of present-day massive galaxies ({log}({M}* /{M}⊙ )=11.5) out to z = 5. We utilize the exceptional depth and area of the latest UltraVISTA data release, combined with the depth and unparalleled seeing of CANDELS to gather a large, mass-selected sample of galaxies in the NIR (rest-frame optical to UV). Progenitors of present-day massive galaxies are identified via an evolving cumulative number density selection, which accounts for the effects of merging to correct for the systematic biases introduced using a fixed cumulative number density selection, and find progenitors grow in stellar mass by ≈ 1.5 {dex} since z = 5. Using stacking, we analyze the structural parameters of the progenitors and find that most of the stellar mass content in the central regions was in place by z˜ 2, and while galaxies continue to assemble mass at all radii, the outskirts experience the largest fractional increase in stellar mass. However, we find evidence of significant stellar mass build-up at r< 3 {kpc} beyond z> 4 probing an era of significant mass assembly in the interiors of present-day massive galaxies. We also compare mass assembly from progenitors in this study to the EAGLE simulation and find qualitatively similar assembly with z at r< 3 {kpc}. We identify z˜ 1.5 as a distinct epoch in the evolution of massive galaxies where progenitors transitioned from growing in mass and size primarily through in situ star formation in disks to a period of efficient growth in r e consistent with the minor merger scenario.

The occurrence of macro- and mesoscopic methane hydrate in the eastern margin of Japan Sea

NASA Astrophysics Data System (ADS)

Matsumoto, R.; Kakuwa, Y.; Tanahashi, M.; Hiruta, A.

2016-12-01

Shallow methane hydrate is known to occur in muddy sediments that were deposited in the eastern margin of Japan Sea. In such settings, the hydrate occurs just below the seabed or is exposed directly on the seabed. Its presence is quite different from the pore-filling type of hydrate typically found in sandstone of the Pacific Ocean side of the Japanese islands. This presentation focuses on categorizing the distribution of gas hydrate in Japan Sea which, until recently, has been poorly understood. Macroscopic occurrence: Numerous gas chimney structures, which are characterized by an acoustic blanking on sub-bottom profiler images, have been discovered in the eastern margin of Japan Sea. We carried out seafloor drilling at several topographic highs that showed gas chimney structures. The results confirm that, while methane hydrate does not occur in the well-stratified part of SBP images, it does occur uniquely in the gas chimney structure-bearing mounds and pockmarks. Several horizons of methane hydrate-concentrated layers are identified by our LWD data and are traceable over lateral distances of as much as a kilometer.. In another case, the methane hydrate-concentrated layers occur stratigraphically in a regular manner with methane-derived carbonate nodules. We interpret the second case as one in which methane gas was supplied by regularly repeated movements of active fault(s). Mesoscopic occurrence: Methane hydrate is classified into 5 types that are readily observable in drilled cores: granular, nodular, platy, veiny and massive. The granular type is common over shallower intervals, while platy and veiny types are more common in the deeper intervals. Nevertheless, a significant fraction of the granular type may have possibly originated from the destruction and dissociation of other types during drilling and recovery. The massive type hydrate that characterizes highly-concentrated layers transitions to other types laterally as methane hydrate becomes poorly concentrated. This study was conducted under the commission from AIST as a part of the methane hydrate research project funded by METI (the Ministry of Economy, Trade and Industry, Japan).

Unusual square roots in the ghost-free theory of massive gravity

NASA Astrophysics Data System (ADS)

Golovnev, Alexey; Smirnov, Fedor

2017-06-01

A crucial building block of the ghost free massive gravity is the square root function of a matrix. This is a problematic entity from the viewpoint of existence and uniqueness properties. We accurately describe the freedom of choosing a square root of a (non-degenerate) matrix. It has discrete and (in special cases) continuous parts. When continuous freedom is present, the usual perturbation theory in terms of matrices can be critically ill defined for some choices of the square root. We consider the new formulation of massive and bimetric gravity which deals directly with eigenvalues (in disguise of elementary symmetric polynomials) instead of matrices. It allows for a meaningful discussion of perturbation theory in such cases, even though certain non-analytic features arise.

Paleointensity results for 0 and 4 ka from Hawaiian lava flows: a new approach to sampling

NASA Astrophysics Data System (ADS)

Cromwell, G.; Tauxe, L.; Staudigel, H.; Ron, H.; Trusdell, F.

2012-04-01

Paleointensity data are typically generated from core samples drilled out of the massive parts of lava flows. During Thellier-Thellier type experiments, these massive samples suffer from very low success rates (~20%), as shown by failure to meet statistical criteria. Low success generally occurs for two reasons: 1) alteration of the sample during the heating process, and 2) multi-domain behavior of massive material. Moreover, recent studies of historical lava flows show that massive samples may not accurately reflect the intensity of the magnetic field even when they are successful (Valet et al., 2010). Alternatively, submarine basaltic glasses (SBG) produce high success rates (~80%) for Thellier-Thellier type experiments, likely due to near instantaneous cooling rates which produce single-domain magnetic grains. In addition, SBG have been proven to produce accurate records of the magnetic field (e.g., Pick and Tauxe, 1993). In this study we investigate the success of paleointensity experiments on subaerial quenched basalts from Hawaii in the quest for single domain, rapidly cooled subaerial analogs to SBG. We also examine the effects of grain size and cooling rate on the accuracy of paleointensity results. During March 2011, we collected samples from 31 dated lava flows (0-3800 BP), including the historical 1950 C.E. and 2010 C.E. flows. Each lava flow was additionally subsampled when unique cooling structures within the unit could be identified. Single-domain, rapidly quenched glasses from the 1950 and 2010 flows are ideally behaved, i.e. straight Arai plots, and accurately record the expected geomagnetic field strength. However, slower cooled specimens from the same flows produce sagged Arai plots and consistently underestimate expected geomagnetic field intensity. Results from ideally behaved glasses over the last 4 ka indicate periods of rapid field change in Hawaii and a possible high intensity field spike around 2.7 ka. We will present new results from our comprehensive data set of Hawaii paleointensity on about the last 4 ka.

High-velocity Interstellar Bullets in IRAS 05506+2414: A Very Young Protostar

NASA Technical Reports Server (NTRS)

Sahai, Raghvendra; Claussen, Mark; Sanchez Contreras, Carmen; Morris, Mark; Sarkar, Geetanjali

2008-01-01

We have made a serendipitous discovery of an enigmatic outflow source, IRAS 05506+2414 (hereafter IRAS 05506), as part of a multiwavelength survey of pre-planetary nebulae (PPNs). The HST optical and near-infrared images show a bright compact central source with a jet-like extension, and a fan-like spray of high-velocity (with radial velocities up to 350 km/s) elongated knots which appear to emanate from it. These structures are possibly analogous to the near-IR bullets'' seen in the Orion Nebula. Interferometric observations at 2.6 mm show the presence of a continuum source and a high-velocity CO outflow, which is aligned with the optical jet structure. IRAS 05506 is most likely not a PPN. We find extended NH3 (1,1) emission toward IRAS 05506; these data, together with the combined presence of far-IR emission, H2O and OH masers, and CO and CS J=2-1 emission, strongly argue for a dense, dusty star-forming core associated with IRAS 05506. IRAS 05506 is probably an intermediate-mass or massive protostar, and the very short timescale (200 yr) of its outflows indicates that it is very young. If IRAS 05506 is a massive star, then the lack of radio continuum and the late G to early K spectral type we find from our optical spectra imply that in this object we are witnessing the earliest stages of its life, while its temperature is still too low to provide sufficient UV flux for ionization.

Massive star winds interacting with magnetic fields on various scales

NASA Astrophysics Data System (ADS)

David-Uraz, A.; Petit, V.; Erba, C.; Fullerton, A.; Walborn, N.; MacInnis, R.

2018-01-01

One of the defining processes which govern massive star evolution is their continuous mass loss via dense, supersonic line-driven winds. In the case of those OB stars which also host a surface magnetic field, the interaction between that field and the ionized outflow leads to complex circumstellar structures known as magnetospheres. In this contribution, we review recent developments in the field of massive star magnetospheres, including current efforts to characterize the largest magnetosphere surrounding an O star: that of NGC 1624-2. We also discuss the potential of the "analytic dynamical magnetosphere" (ADM) model to interpret multi-wavelength observations. Finally, we examine the possible effects of — heretofore undetected — small-scale magnetic fields on massive star winds and compare their hypothetical consequences to existing, unexplained observations.

THE LOCATION, CLUSTERING, AND PROPAGATION OF MASSIVE STAR FORMATION IN GIANT MOLECULAR CLOUDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ochsendorf, Bram B.; Meixner, Margaret; Chastenet, Jérémy

Massive stars are key players in the evolution of galaxies, yet their formation pathway remains unclear. In this work, we use data from several galaxy-wide surveys to build an unbiased data set of ∼600 massive young stellar objects, ∼200 giant molecular clouds (GMCs), and ∼100 young (<10 Myr) optical stellar clusters (SCs) in the Large Magellanic Cloud. We employ this data to quantitatively study the location and clustering of massive star formation and its relation to the internal structure of GMCs. We reveal that massive stars do not typically form at the highest column densities nor centers of their parentmore » GMCs at the ∼6 pc resolution of our observations. Massive star formation clusters over multiple generations and on size scales much smaller than the size of the parent GMC. We find that massive star formation is significantly boosted in clouds near SCs. However, whether a cloud is associated with an SC does not depend on either the cloud’s mass or global surface density. These results reveal a connection between different generations of massive stars on timescales up to 10 Myr. We compare our work with Galactic studies and discuss our findings in terms of GMC collapse, triggered star formation, and a potential dichotomy between low- and high-mass star formation.« less

Novel features of Brassica napus embryogenic microspores revealed by high pressure freezing and freeze substitution: evidence for massive autophagy and excretion-based cytoplasmic cleaning.

PubMed

Corral-Martínez, Patricia; Parra-Vega, Verónica; Seguí-Simarro, Jose M

2013-07-01

Induction of embryogenesis from isolated microspore cultures is a complex experimental system where microspores undergo dramatic changes in developmental fate. After ~40 years of application of electron microscopy to the study of the ultrastructural changes undergone by the induced microspore, there is still room for new discoveries. In this work, high pressure freezing and freeze substitution (HPF/FS), the best procedures known to date for ultrastructural preservation, were used to process Brassica napus microspore cultures covering all the stages of microspore embryogenesis. Analysis of these cultures by electron microscopy revealed massive processes of autophagy exclusively in embryogenic microspores, but not in other microspore-derived structures also present in cultures. However, a significant part of the autophagosomal cargo was not recycled. Instead, it was transported out of the cell, producing numerous deposits of extracytoplasmic fibrillar and membranous material. It was shown that commitment of microspores to embryogenesis is associated with both massive autophagy and excretion of the removed material. It is hypothesized that autophagy would be related to the need for a profound cytoplasmic cleaning, and excretion would be a mechanism to avoid excessive growth of the vacuolar system. Together, the results also demonstrate that the application of HPF/FS to the study of the androgenic switch is the best option currently available to identify the complex and dramatic ultrastructural changes undergone by the induced microspore. In addition, they provide significant insights to understand the cellular basis of induction of microspore embryogenesis, and open a new door for the investigation of this intriguing developmental pathway.

The Concept of Openness behind c- and x-MOOCs (Massive Open Online Courses)

ERIC Educational Resources Information Center

Rodriguez, Osvaldo

2013-01-01

The last five years have witnessed a hype about MOOCs (Massive Open Online Courses) presaging a revolution in higher education. Although all MOOCs have in common their scale and free access, they have already bifurcated in two very distinct types of courses when compared in terms of their underpinning theory, format and structure, known as c-MOOCs…

Split Octonion Reformulation for Electromagnetic Chiral Media of Massive Dyons

NASA Astrophysics Data System (ADS)

Chanyal, B. C.

2017-12-01

In an explicit, unified, and covariant formulation of an octonion algebra, we study and generalize the electromagnetic chiral fields equations of massive dyons with the split octonionic representation. Starting with 2×2 Zorn’s vector matrix realization of split-octonion and its dual Euclidean spaces, we represent the unified structure of split octonionic electric and magnetic induction vectors for chiral media. As such, in present paper, we describe the chiral parameter and pairing constants in terms of split octonionic matrix representation of Drude-Born-Fedorov constitutive relations. We have expressed a split octonionic electromagnetic field vector for chiral media, which exhibits the unified field structure of electric and magnetic chiral fields of dyons. The beauty of split octonionic representation of Zorn vector matrix realization is that, the every scalar and vector components have its own meaning in the generalized chiral electromagnetism of dyons. Correspondingly, we obtained the alternative form of generalized Proca-Maxwell’s equations of massive dyons in chiral media. Furthermore, the continuity equations, Poynting theorem and wave propagation for generalized electromagnetic fields of chiral media of massive dyons are established by split octonionic form of Zorn vector matrix algebra.

A General Precipitation-limited L X–T–R Relation among Early-type Galaxies

NASA Astrophysics Data System (ADS)

Voit, G. Mark; Ma, C. P.; Greene, J.; Goulding, A.; Pandya, V.; Donahue, M.; Sun, M.

2018-01-01

The relation between X-ray luminosity (L X) and ambient gas temperature (T) among massive galactic systems is an important cornerstone of both observational cosmology and galaxy-evolution modeling. In the most massive galaxy clusters, the relation is determined primarily by cosmological structure formation. In less massive systems, it primarily reflects the feedback response to radiative cooling of circumgalactic gas. Here we present a simple but powerful model for the L X–T relation as a function of physical aperture R within which those measurements are made. The model is based on the precipitation framework for AGN feedback and assumes that the circumgalactic medium is precipitation-regulated at small radii and limited by cosmological structure formation at large radii. We compare this model with many different data sets and show that it successfully reproduces the slope and upper envelope of the L X–T–R relation over the temperature range from ∼0.2 keV through ≳ 10 {keV}. Our findings strongly suggest that the feedback mechanisms responsible for regulating star formation in individual massive galaxies have much in common with the precipitation-triggered feedback that appears to regulate galaxy-cluster cores.

GPU-Meta-Storms: computing the structure similarities among massive amount of microbial community samples using GPU.

PubMed

Su, Xiaoquan; Wang, Xuetao; Jing, Gongchao; Ning, Kang

2014-04-01

The number of microbial community samples is increasing with exponential speed. Data-mining among microbial community samples could facilitate the discovery of valuable biological information that is still hidden in the massive data. However, current methods for the comparison among microbial communities are limited by their ability to process large amount of samples each with complex community structure. We have developed an optimized GPU-based software, GPU-Meta-Storms, to efficiently measure the quantitative phylogenetic similarity among massive amount of microbial community samples. Our results have shown that GPU-Meta-Storms would be able to compute the pair-wise similarity scores for 10 240 samples within 20 min, which gained a speed-up of >17 000 times compared with single-core CPU, and >2600 times compared with 16-core CPU. Therefore, the high-performance of GPU-Meta-Storms could facilitate in-depth data mining among massive microbial community samples, and make the real-time analysis and monitoring of temporal or conditional changes for microbial communities possible. GPU-Meta-Storms is implemented by CUDA (Compute Unified Device Architecture) and C++. Source code is available at http://www.computationalbioenergy.org/meta-storms.html.

A Survey of Extended H_{2} Emission Towards a Sample of Massive YSOs

NASA Astrophysics Data System (ADS)

Navarete, F.; Damineli, A.; Barbosa, C. L.; Blum, R. D.

2014-10-01

Very few massive stars in early formation stages were clearly identified in the Milky Way and moreover, the processes of formation of such objects lacks of observational evidences. Two theories predict the formation of massive star: i) by merging of low mass stars or ii) by an accretion disk. One of the most prominent evidences for the accretion scenario is the presence of bipolar outflows associated to the central sources. Those structures were found on both intermediate and low-mass YSOs, but there are no evidences for associations with MYSOs. Based on that, a survey was designed to investigate the earliest stages of massive star formation through the molecular hydrogen transition at 2.12μm. A sample of ˜ 300 MYSOs candidates was selected from the Red MSX Source program and the sources were observed with the IR cameras Spartan (SOAR, Chile) and WIRCam (CFHT, Hawaii). Extended H_{2} emission was found toward 55% of the sample and 30% of the positive detections (50 sources) have bipolar morphology, suggesting collimated outflows. These results support the accretion scenario, since the merging of low mass stars would not produce jet-like structures.

Thermo-mechanical simulations of early-age concrete cracking with durability predictions

NASA Astrophysics Data System (ADS)

Havlásek, Petr; Šmilauer, Vít; Hájková, Karolina; Baquerizo, Luis

2017-09-01

Concrete performance is strongly affected by mix design, thermal boundary conditions, its evolving mechanical properties, and internal/external restraints with consequences to possible cracking with impaired durability. Thermo-mechanical simulations are able to capture those relevant phenomena and boundary conditions for predicting temperature, strains, stresses or cracking in reinforced concrete structures. In this paper, we propose a weakly coupled thermo-mechanical model for early age concrete with an affinity-based hydration model for thermal part, taking into account concrete mix design, cement type and thermal boundary conditions. The mechanical part uses B3/B4 model for concrete creep and shrinkage with isotropic damage model for cracking, able to predict a crack width. All models have been implemented in an open-source OOFEM software package. Validations of thermo-mechanical simulations will be presented on several massive concrete structures, showing excellent temperature predictions. Likewise, strain validation demonstrates good predictions on a restrained reinforced concrete wall and concrete beam. Durability predictions stem from induction time of reinforcement corrosion, caused by carbonation and/or chloride ingress influenced by crack width. Reinforcement corrosion in concrete struts of a bridge will serve for validation.

Massive ovarian oedema: a misleading clinical entity.

PubMed

Machairiotis, Nikolaos; Stylianaki, Aikaterini; Kouroutou, Paraskevi; Sarli, Polixeni; Alexiou, Nikolaos Konstantinos; Efthymiou, Elias; Maras, Athanasios; Alexiou, Nikolaos Georgios; Nikolaou, Spyridon Evaggelos; Courcoutsakis, Nikolaos; Papakonstantinou, Eleni; Zarogoulidis, Paul; Barbetakis, Nikolaos; Paliouras, Dimitrios; Gogakos, Apostolos; Machairiotis, Christodoulos

2016-02-03

Massive ovarian oedema is a rare non-neoplastic clinicopathologic entity has a higher incidence in women during their second and third life decade. The oedema can be presented in one or both ovaries as a result of partial intermittent torsion of the ovarian pedicle that interferes to the venal and lymphatic drainage of the ovary. We present a clinical case of a 16 year old with massive ovarian oedema and we performed a review of the literature. The pathophysiology of this entity is very complex. We tried to perform a complete review of the literature and focus on the complexity of this entity as far as its pathophysiological backround is concerned and as far as its clinical presentation is concerned. In conclusion, massive ovarian oedema is a rare, multi disease mimicking clinical entity, with an acute or progressive clinical presentation. It has also to be a part of our differential diagnosis in cases of acute abdominal pain and we have to try to treat her conservatively, in order to preserve fertility.

Mapping the Traces of the Assembly and Multistage Breakup of Gondwanaland in the Lithosphere of Madagascar

NASA Astrophysics Data System (ADS)

Rindraharisaona, E. J.; Tilmann, F. J.; Yuan, X.; Rumpker, G.; Heit, B.; Rambolamanana, G.; Priestley, K. F.

2014-12-01

Madagascar is an ideal place to study the multistage assembly and break up of Gondwanaland, the supercontinent whose breakup also gave rise to most of present day continental regions. At the end of the Proterozoic the assembly of Gondwanaland has placed the Malagasy basement between the Antarctic, Dharwar, Arabo-Nubian and Nubian-Tanzanian cratons. The continental collision processes accompanying the assembly left their mark on the Malagasy basement, currently exposed in the Eastern two thirds of the island, in the form of metamorphic and mineral belts as well as massive ductile shear zones. During the Jurassic Madagascar, India and Seychelles were breaking up from African. Long after the breakaway of India and the Seychelles from Madagascar (Cretaceous time), volcanic activation has occurred in several locations of Madagascar mostly in the central and northern part (Neogene period). The surface traces of assembly and breakup processes have been studied extensively using geological methods in Madagascar but the imprint on the deep structure has so far not been studied in much detail. Between 2012 and 2014, 25 broadband stations were operated in the Southern Madagascar extending from East coast (Mananjary) to West coast (Toliary). The array crosses the Bongolava-Ranontsara shear zone, which is one of the major shear zones in Madagascar. In addition, between 2013 and 2014, 25 short period stations were deployed in the southeastern part of Madagascar. We will present preliminarily results of the lithosphere structure in the southern part of Madagascar based on surface wave dispersion analysis from both earthquakes and ambient noise combine with receiver function analysis. We will focus mostly on the contrast between the lithosphere structure in the eastern (Precambrian rocks) and the western (Sedimentary basins) parts of Madagascar.

The multi-modal Australian ScienceS Imaging and Visualization Environment (MASSIVE) high performance computing infrastructure: applications in neuroscience and neuroinformatics research

PubMed Central

Goscinski, Wojtek J.; McIntosh, Paul; Felzmann, Ulrich; Maksimenko, Anton; Hall, Christopher J.; Gureyev, Timur; Thompson, Darren; Janke, Andrew; Galloway, Graham; Killeen, Neil E. B.; Raniga, Parnesh; Kaluza, Owen; Ng, Amanda; Poudel, Govinda; Barnes, David G.; Nguyen, Toan; Bonnington, Paul; Egan, Gary F.

2014-01-01

The Multi-modal Australian ScienceS Imaging and Visualization Environment (MASSIVE) is a national imaging and visualization facility established by Monash University, the Australian Synchrotron, the Commonwealth Scientific Industrial Research Organization (CSIRO), and the Victorian Partnership for Advanced Computing (VPAC), with funding from the National Computational Infrastructure and the Victorian Government. The MASSIVE facility provides hardware, software, and expertise to drive research in the biomedical sciences, particularly advanced brain imaging research using synchrotron x-ray and infrared imaging, functional and structural magnetic resonance imaging (MRI), x-ray computer tomography (CT), electron microscopy and optical microscopy. The development of MASSIVE has been based on best practice in system integration methodologies, frameworks, and architectures. The facility has: (i) integrated multiple different neuroimaging analysis software components, (ii) enabled cross-platform and cross-modality integration of neuroinformatics tools, and (iii) brought together neuroimaging databases and analysis workflows. MASSIVE is now operational as a nationally distributed and integrated facility for neuroinfomatics and brain imaging research. PMID:24734019

Capacitance-based damage detection sensing for aerospace structural composites

NASA Astrophysics Data System (ADS)

Bahrami, P.; Yamamoto, N.; Chen, Y.; Manohara, H.

2014-04-01

Damage detection technology needs improvement for aerospace engineering application because detection within complex composite structures is difficult yet critical to avoid catastrophic failure. Damage detection is challenging in aerospace structures because not all the damage detection technology can cover the various defect types (delamination, fiber fracture, matrix crack etc.), or conditions (visibility, crack length size, etc.). These defect states are expected to become even more complex with future introduction of novel composites including nano-/microparticle reinforcement. Currently, non-destructive evaluation (NDE) methods with X-ray, ultrasound, or eddy current have good resolutions (< 0.1 mm), but their detection capabilities is limited by defect locations and orientations and require massive inspection devices. System health monitoring (SHM) methods are often paired with NDE technologies to signal out sensed damage, but their data collection and analysis currently requires excessive wiring and complex signal analysis. Here, we present a capacitance sensor-based, structural defect detection technology with improved sensing capability. Thin dielectric polymer layer is integrated as part of the structure; the defect in the structure directly alters the sensing layer's capacitance, allowing full-coverage sensing capability independent of defect size, orientation or location. In this work, capacitance-based sensing capability was experimentally demonstrated with a 2D sensing layer consisting of a dielectric layer sandwiched by electrodes. These sensing layers were applied on substrate surfaces. Surface indentation damage (~1mm diameter) and its location were detected through measured capacitance changes: 1 to 250 % depending on the substrates. The damage detection sensors are light weight, and they can be conformably coated and can be part of the composite structure. Therefore it is suitable for aerospace structures such as cryogenic tanks and rocket fairings for example. The sensors can also be operating in space and harsh environment such as high temperature and vacuum.

The Wolf-Rayet Content of the Andromeda Galaxy: What Do Massive Stars Really Do When the Metallicity is Above Solar?

NASA Astrophysics Data System (ADS)

Massey, Philip

2000-08-01

We are proposing to survey M 31 for Wolf-Rayet stars (WRs) and red supergiants (RSGs), providing much needed information about how massive stars evolve at greater-than-solar metallicities. Our understanding of massive star evolution is hampered by the effects of mass-loss on these stars; at higher metallicities mass-loss effects become ever more pronounced. Our previous work on other Local Group galaxies (Massey & Johnson 1998) has shown that the number of RSGs to WRs correlates well with metallicity, changing by a factor of 6 from NGC 6822 (log O/H+12=8.3) to the inner parts of M 33 (8.7). Our study of five small regions in M 31 suggests that above this value the ratio of RSGs to WRs doesn't change: does this mean that no massive star that becomes a WR spends any time as a RSG at above solar metallicities? We fear instead that our sample (selected, afterall, for containing WR stars) was not sufficiently well-mixed in age to provide useful global values; the study we propose here will survey all of M 31. Detection of WRs will provide fundamental data not only on massive star evolution, but also act as tracers of the most massive stars, and improve our knowledge of recent star-formation in the Andromeda Galaxy.

Assessment of disaster preparedness among emergency departments in Italian hospitals: a cautious warning for disaster risk reduction and management capacity.

PubMed

Paganini, Matteo; Borrelli, Francesco; Cattani, Jonathan; Ragazzoni, Luca; Djalali, Ahmadreza; Carenzo, Luca; Della Corte, Francesco; Burkle, Frederick M Jr; Ingrassia, Pier Luigi

2016-08-15

Since the 1990s, Italian hospitals are required to comply with emergency disaster plans known as Emergency Plan for Massive Influx of Casualties. While various studies reveal that hospitals overall suffer from an insufficient preparedness level, the aim of this study was to better determine the preparedness level of Emergency Departments of Italian hospitals by assessing the knowledge-base of emergency physicians regarding basic disaster planning and procedures. A prospective observational study utilized a convenience sample of Italian Emergency Departments identified from the Italian Ministry of Health website. Anonymous telephone interviews were conducted of medical consultants in charge at the time in the respective Emergency Departments, and were structured in 3 parts: (1) general data and demographics, (2) the current disaster plan and (3) protocols and actions of the disaster plan. Eighty-five Emergency Departments met inclusion criteria, and 69 (81 %) agreed to undergo the interview. Only 45 % of participants declared to know what an Emergency Plan for Massive Influx of Casualties is, 41 % believed to know who has the authority to activate the plan, 38 % knew who is in charge of intra-hospital operations. In Part 3 physicians revealed a worrisome inconsistency in critical content knowledge of their answers. Results demonstrate a poor knowledge-base of basic hospital disaster planning concepts by Italian Emergency Department physicians-on-duty. These findings should alert authorities to enhance staff disaster preparedness education, training and follow-up to ensure that these plans are known to all who have responsibility for disaster risk reduction and management capacity.

Science from a glimpse: Hubble SNAPshot observations of massive galaxy clusters

NASA Astrophysics Data System (ADS)

Repp, A.; Ebeling, H.

2018-06-01

Hubble Space Telescope SNAPshot surveys of 86 X-ray selected galaxy clusters at 0.3 < z < 0.5 from the MACS sample have proven invaluable for the exploration of a wide range of astronomical research topics. We here present an overview of the four MACS SNAPshot surveys conducted from Cycle 14 to Cycle 20 as part of a long-term effort aimed at identifying exceptional cluster targets for in-depth follow up by the extragalactic community. We also release redshifts and X-ray luminosities of all clusters observed as part of this initiative. To illustrate the power of SNAPshot observations of MACS clusters, we explore several aspects of galaxy evolution illuminated by the images obtained for these programmes. We confirm the high lensing efficiency of X-ray selected clusters at z > 0.3. Examining the evolution of the slope of the cluster red sequence, we observe at best a slight decrease with redshift, indicating minimal age contribution since z ˜ 1. Congruent to previous studies' findings, we note that the two BCGs which are significantly bluer (≥5σ) than their clusters' red sequences reside in relaxed clusters and exhibit pronounced internal structure. Thanks to our targets' high X-ray luminosity, the subset of our sample observed with Chandra adds valuable leverage to the X-ray luminosity-optical richness relation, which, albeit with substantial scatter, is now clearly established from groups to extremely massive clusters of galaxies. We conclude that SNAPshot observations of MACS clusters stand to continue to play a vital pathfinder role for astrophysical investigations across the entire electromagnetic spectrum.

Insights into the crustal structure of the transition between Nares Strait and Baffin Bay

NASA Astrophysics Data System (ADS)

Altenbernd, Tabea; Jokat, Wilfried; Heyde, Ingo; Damm, Volkmar

2016-11-01

The crustal structure and continental margin between southern Nares Strait and northern Baffin Bay were studied based on seismic refraction and gravity data acquired in 2010. We present the resulting P wave velocity, density and geological models of the crustal structure of a profile, which extends from the Greenlandic margin of the Nares Strait into the deep basin of central northern Baffin Bay. For the first time, the crustal structure of the continent-ocean transition of the very northern part of Baffin Bay could be imaged. We divide the profile into three parts: continental, thin oceanic, and transitional crust. On top of the three-layered continental crust, a low-velocity zone characterizes the lowermost layer of the three-layered Thule Supergroup underneath Steensby Basin. The 4.3-6.3 km thick oceanic crust in the southern part of the profile can be divided into a northern and southern section, more or less separated by a fracture zone. The oceanic crust adjacent to the continent-ocean transition is composed of 3 layers and characterized by oceanic layer 3 velocities of 6.7-7.3 km/s. Toward the south only two oceanic crustal layers are necessary to model the travel time curves. Here, the lower oceanic crust has lower seismic velocities (6.4-6.8 km/s) than in the north. Rather low velocities of 7.7 km/s characterize the upper mantle underneath the oceanic crust, which we interpret as an indication for the presence of upper mantle serpentinization. In the continent-ocean transition zone, the velocities are lower than in the adjacent continental and oceanic crustal units. There are no signs for massive magmatism or the existence of a transform margin in our study area.

The Danieli Inventory of Multigenerational Legacies of Trauma, Part I: Survivors' posttrauma adaptational styles in their children's eyes.

PubMed

Danieli, Yael; Norris, Fran H; Lindert, Jutta; Paisner, Vera; Engdahl, Brian; Richter, Julia

2015-09-01

A comprehensive valid behavioral measure for assessing multidimensional multigenerational impacts of massive trauma has been missing thus far. We describe the development of the Posttrauma Adaptational Styles questionnaire (Part I of the three-part Danieli Inventory of Multigenerational Legacies of Trauma), a self-report questionnaire of Holocaust survivors' children's perceptions of each parent and their own upbringing (60 items per parent). The items were based on literature and cognitive interviewing of 18 survivors' offspring. A web-based convenience sample survey was designed in English and Hebrew and completed by 482 adult children (M age = 59; 67% women) of Holocaust survivors. Exploratory factor analyses were conducted by using maximum likelihood extraction with Geomin rotation to examine the factor structure of the original 70 items for each parent. Conducted hierarchically, the analysis yielded three higher-order factors reflecting intensities of victim, numb, and fighter styles. The 30-item Victim Style Scale (α = .92-.93) and 18-item Numb Style Scale (α = .89) had excellent internal consistency; the consistency of the 12-item Fighter Style Scale (α = .69-.70) was more modest. English-Hebrew analyses suggested good-to-excellent congruence in factor structure (φ = .87-.99). Further research is needed to evaluate the validity of the measure in other samples and populations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Geology, ore facies and sulfur isotopes geochemistry of the Nudeh Besshi-type volcanogenic massive sulfide deposit, southwest Sabzevar basin, Iran

NASA Astrophysics Data System (ADS)

Maghfouri, Sajjad; Rastad, Ebrahim; Mousivand, Fardin; Lin, Ye; Zaw, Khin

2016-08-01

The southwest Sabzevar basin is placed in the southwestern part of a crustal domain known as the Sabzevar zone, at the north of Central Iranian microcontinent. This basin hosts abundant mineral deposits; particularly of the Mn exhalative and Cu-Zn volcanogenic massive sulfide (VMS) types. The evolution of this basin is governed by the Neo-tethys oceanic crust subduction beneath the Central Iranian microcontinent and by the resulting continental arc (Sanandaj-Sirjan) and back-arc (Sabzevar-Naien). This evolution followed two major sequences: (I) Lower Late Cretaceous Volcano-Sedimentary Sequence (LLCVSS), which is indicated by fine-grained siliciclastic sediments, gray basic coarse-grained different pyroclastic rocks and bimodal volcanism. During this stage, tuff-hosted stratiform, exhalative Mn deposits (Nudeh, Benesbourd, Ferizy and Goft), oxide Cu deposits (Garab and Ferizy) and Cu-Zn VMS (Nudeh, Chun and Lala) deposits formed. (II) Upper Late Cretaceous Sedimentary Dominated Sequence (ULCSS), including pelagic limestone, marly tuff, silty limestone and marl with minor andesitic tuff rocks. The economically most important Mn (Zakeri and Cheshmeh-sefid) deposits of Sabzevar zone occur within the marly tuff of this sequence. The Nudeh Cu-Zn volcanogenic massive sulfide (VMS) deposit is situated in the LLCVSS. The host-rock of deposits consists of alkali olivine basalt flow and tuffaceous silty sandstone. Mineralization occurs as stratiform blanket-like and tabular orebodies. Based on ore body structure, mineralogy, and ore fabric, we recognize three different ore facies in the Nudeh deposit: (1) a stringer zone, consisting of a discordant mineralization of sulfides forming a stockwork of sulfide-bearing quartz veins cutting the footwall volcano-sedimentary rocks; (2) a massive ore, consisting of massive replacement pyrite, chalcopyrite, sphalerite and Friedrichite with magnetite; (3) bedded ore, with laminated to disseminated pyrite, and chalcopyrite. Chloritization, silicification, sericitization and epidotization are the main wall-rock alterations; alteration intensity increases towards the stringer zone. The δ34S composition of the sulfides ranges from -1.5‰ to +3.69‰ with a general increase of δ34S ratios of massive ore facies to stockwork zone. The heavier values indicate that some of the sulfur was derived from seawater sulfate that was ultimately thermochemically reduced in deep hydrothermal reaction zones. Sulfur isotopes, along with sedimentological, textural, petrological, mineralogical, and geochemical evidences, suggest that this deposit should be classified as a Besshi-type VMS ore deposit.

Peripheral and central auditory specialization in a gliding marsupial, the feathertail glider, Acrobates pygmaeus.

PubMed

Aitkin, L M; Nelson, J E

1989-01-01

Two specialized features are described in the auditory system of Acrobates pygmaeus, a small gliding marsupial. Firstly, the ear canal includes a transverse disk of bone that partly occludes the canal near the eardrum. The resultant narrow-necked chamber above the eardrum appears to attenuate sound across a broad frequency range, except at 27-29 kHz at which a net gain of sound pressure occurs. Secondly, the lateral medulla is hypertrophied at the level of the cochlear nucleus, forming a massive lateral lobe comprised of multipolar cells and granule cells. This lobe has connections with the auditory nerve and the cerebellum. Speculations are advanced about the functions of these structures in gliding behaviour and predator avoidance.

The singular behavior of massive QCD amplitudes

NASA Astrophysics Data System (ADS)

Mitov, Alexander; Moch, Sven-Olaf

2007-05-01

We discuss the structure of infrared singularities in on-shell QCD amplitudes with massive partons and present a general factorization formula in the limit of small parton masses. The factorization formula gives rise to an all-order exponentiation of both, the soft poles in dimensional regularization and the large collinear logarithms of the parton masses. Moreover, it provides a universal relation between any on-shell amplitude with massive external partons and its corresponding massless amplitude. For the form factor of a heavy quark we present explicit results including the fixed-order expansion up to three loops in the small mass limit. For general scattering processes we show how our constructive method applies to the computation of all singularities as well as the constant (mass-independent) terms of a generic massive n-parton QCD amplitude up to the next-to-next-to-leading order corrections.

Entrapment and near Miss: A Comparative Analysis of Psycho-Structural Elements in Gambling Games and Massively Multiplayer Online Role-Playing Games

ERIC Educational Resources Information Center

Karlsen, Faltin

2011-01-01

While massively multiplayer online role-playing games like World of Warcraft are often accused of leading to excessive and harmful playing, the only gaming activity that is internationally recognized as a pathological disorder is excessive gambling. The present article seeks to establish empirical data on potential harmful online gaming through a…

Massive sulfide exploration models of the Iberian Pyrite Belt Neves Corvo mine region, based in a 3D geological, geophysical and geochemical ProMine study

NASA Astrophysics Data System (ADS)

Inverno, Carlos; Matos, João Xavier; Rosa, Carlos; Mário Castelo-Branco, José; Granado, Isabel; Carvalho, João; João Baptista, Maria; Represas, Patrícia; Pereira, Zélia; Oliveira, Tomás; Araujo, Vitor

2013-04-01

The Iberian Pyrite Belt (IPB) hosts one of the largest concentrations of massive sulfides in the Earth's crust. This highly productive VMS belt contains more than 85 massive sulfide deposits, totalling an estimate of 1600 Mt of massive ore and about 250 Mt of stockwork ore (Leistel et al., 1998; Oliveira et al., 2005; Tornos, 2006). Included in the South Portuguese Zone the IPB is represented by the Phyllite-Quartzite Group (PQG) composed of shales and quartzites of late Devonian age followed by the Volcanic-Sedimentary Complex (VSC) a submarine succession of sediments and felsic and basic volcanic rocks (late Famennian-late Viséan age). Above the IPB a turbidite sedimentary unit occurs being represented by the Baixo Alentejo Flysch Group (BAFG). The ore deposits are hosted by felsic volcanic rocks and sediments that are dominant in the lower part of the VSC succession. The Neves Corvo (ProMine, EU FP7) project area is focused on the Neves Corvo deposit, an active copper mine. The project area is located between the Messejana Fault and the Portuguese/Spanish border which has been selected for the 3D geological and geophysical modelling study, based on high exploration potential of the Neves Corvo area (Oliveira et al. 2006, Relvas et al. 2006, Pereira et al. 2008, Rosa et al. 2008, Matos et al. 2011, Oliveira et al. 2013). In this study existing LNEG and AGC geological, geophysical and geochemistry databases were considered. New surveys were done: i) - A physical volcanology and palynostratigraphic age data study and log of the Cotovio drill-hole core (1,888 m, drilled by AGC). ii) - Interpretation of 280 km of Squid TEM performed by AGC. Based on the TEM data, significant conductors have been identified related with: shallow conductive cover, graphitic shale, black shale and sulphide mineralizations. The most important TEM conductors are related with the Neves Corvo massive sulphides lenses (1-10 Ωm). iii) - Ground and residual gravimetry studies including superficial directional derivatives to obtain the various directions of the late-Variscan faults, the main overthrusts and lithological structures. iv) - Detailed palynological sediment dating; v) - A seismic survey was conducted in the vicinities of the Neves Corvo mine totalling 82 km of profiles with target depth of over 10 km. A 3D regional model has been constructed for the selected IPB area using GoCAD, integrating the most critical information of the follow geological units: the lower unit BAFG Mértola Formation, the VSC, the Neves Corvo ores and the PQG. It incorporated surface regional geological maps, 168 drill-hole geological logs throughout the area, structural and tectonic data, former seismic sections, where available, and a digital terrain model. Chemical data from 42 selected drill-holes in order to outline in 3D the Cu distribution in the area. The results have already indicated new important guidelines for VHMS exploration and new regional correlations with the Neves Corvo mining area. The 3D modelling study was essential to the detail understanding of the complex IPB geological structures observed in the south of Portugal.

Massive integration of diverse protein quality assessment methods to improve template based modeling in CASP11

PubMed Central

Cao, Renzhi; Bhattacharya, Debswapna; Adhikari, Badri; Li, Jilong; Cheng, Jianlin

2015-01-01

Model evaluation and selection is an important step and a big challenge in template-based protein structure prediction. Individual model quality assessment methods designed for recognizing some specific properties of protein structures often fail to consistently select good models from a model pool because of their limitations. Therefore, combining multiple complimentary quality assessment methods is useful for improving model ranking and consequently tertiary structure prediction. Here, we report the performance and analysis of our human tertiary structure predictor (MULTICOM) based on the massive integration of 14 diverse complementary quality assessment methods that was successfully benchmarked in the 11th Critical Assessment of Techniques of Protein Structure prediction (CASP11). The predictions of MULTICOM for 39 template-based domains were rigorously assessed by six scoring metrics covering global topology of Cα trace, local all-atom fitness, side chain quality, and physical reasonableness of the model. The results show that the massive integration of complementary, diverse single-model and multi-model quality assessment methods can effectively leverage the strength of single-model methods in distinguishing quality variation among similar good models and the advantage of multi-model quality assessment methods of identifying reasonable average-quality models. The overall excellent performance of the MULTICOM predictor demonstrates that integrating a large number of model quality assessment methods in conjunction with model clustering is a useful approach to improve the accuracy, diversity, and consequently robustness of template-based protein structure prediction. PMID:26369671

Routing performance analysis and optimization within a massively parallel computer

DOEpatents

Archer, Charles Jens; Peters, Amanda; Pinnow, Kurt Walter; Swartz, Brent Allen

2013-04-16

An apparatus, program product and method optimize the operation of a massively parallel computer system by, in part, receiving actual performance data concerning an application executed by the plurality of interconnected nodes, and analyzing the actual performance data to identify an actual performance pattern. A desired performance pattern may be determined for the application, and an algorithm may be selected from among a plurality of algorithms stored within a memory, the algorithm being configured to achieve the desired performance pattern based on the actual performance data.

Trace element content of gossans at four mines in the West Shasta massive sulfide district.

USGS Publications Warehouse

Sanzolone, R.F.; Domenico, J.A.

1985-01-01

Paired analyses of the spongy whole-rock gossan and its botryoidal crust ("chipped rock rind') show little differences, whereas duplicate samples of each at individual sites show such extreme differences as to preclude the use of the data in areal mapping. Gossans from disseminated sulphides have lower and less variable trace-element contents than gossans from massive sulphides, due in part to dilution by rock silicates. Computer reduction of the data by a regionalizing algorithm enables determination of pattern differences among the four mines.-G.J.N.

Ultrasonic scissors-assisted 'open-book' thyroidectomy in massive goiter compressing airway and causing unilateral vocal cord paralysis.

PubMed

M, Irfan; Yaroko, Ali Ango; S M, Najeb; Periasamy, Centilnathan

2013-04-01

A massive goiter may constrict the trachea resulting in shortness of breath. Recurrent laryngeal nerve compression may cause vocal cord paralysis. We highlight a case of a 62- year-old female with a 30 year history of an anterior neck swelling gradually increasing in size. She presented with acute symptoms of upper airway obstruction and voice changes. Emergency thyroidectomy was performed by dividing the middle part of the gland using ultrasonic scissors. The recovery was uneventful and the patient regained normal vocal cord function post operatively.

Basaltic ring structures of the Serra Geral Formation at the southern Triângulo Mineiro, Água Vermelha region, Brazil

NASA Astrophysics Data System (ADS)

Pacheco, Fernando Estevão Rodrigues Crincoli; Caxito, Fabricio de Andrade; Moraes, Lucia Castanheira de; Marangoni, Yara Regina; Santos, Roberto Paulo Zanon dos; Pedrosa-Soares, Antonio Carlos

2018-04-01

The Serra Geral Formation constitutes a continental magmatic province on the southern part of South America within the Paraná basin. Basaltic magmatism of the Serra Geral Formation occurred as extrusions at around 134.5 to 131.5 My ago. The formation is part of the Paraná-Etendeka large igneous province, spanning South America and southwestern Africa. The main extrusion mechanism was probably through fissures related to extensional regime during the breakup of Gondwana in the Cretaceous. Basaltic ring structures (BRS) with tens of meters of diameter, cropping out downstream of Grande river at Água Vermelha hydroelectric dam in southern Triângulo Mineiro region, enable the study of the mechanism of extrusion. The origin of the BRS has been subject to differing interpretations in the past, either collapsed lava flows or central conduits. Detailed geological mapping at 1:1000 scale, stratigraphic, petrographic and gravimetric analysis of the most well preserved of the BRS, with a 200 m diameter, has enabled the description of thirteen different basalt lava flows, along with single a central lava lake and a ring dyke structure. The central flow, interpreted as a preserved lava lake, comprises vesicle- and amygdale-rich basalt, spatter, ropy and degassing structures. The most basal of the thirteen lava flows has massive basalt containing geodes filled with quartz. Above, the lava flows show massive basalt with vertical columnar jointing where is possible to identify the top and bottom of each individual flow, with gentle dips towards the perimeter of the structure. A prominent ring dyke dipping towards the lava lake presents horizontal columnar jointing and cuts the basal and central flows. The gravimetric analysis shows a weak negative Bouguer anomaly on the center of the BRS. The proposed model describes the volcanism of the region in three main steps: (1) fissure flow occurs with lava input; (2) this lava cools and crystallizes cementing most of the fissures, promoting the formation of localized central conduits; and (3) the presence of dissolved gas in lava produces ring and radial fractures around the solidified lava lake. The magma uses some of the ring fissures to ascend and the following lava flows assume the ring shape of the dyke vent. Thus, the BRS in Água Vermelha region can be interpreted as remnants of central conduits representing the late stage magmatism of the Serra Geral Formation.

YBa_2Cu_3O_{7-δ} : in pursuit of the ideal microstructure

NASA Astrophysics Data System (ADS)

Smith, D. S.; Suasmoro, S.; Lejeune, M.; Rabier, J.; Denanot, M. F.; Heintz, J. M.; Magro, C.; Bonnet, J. P.

1992-02-01

This paper examines the role of different factors in the microstructure of ceramic YBa2Cu3O{7-δ} with emphasis on its electrical response. In particular we discuss : 1. the effect of microstructural variations on j_c and ρ_{300}, 2. measurement of j_c, 3. the presence of minor phases and carbonates, 4. oxygen uptake and microcracks, 5. plastic deformation and related structural defects. Dans cet article, nous examinons d'une part la réponse électrique de céramiques supraconductrices massives de type YBa2Cu3O{7-δ} et d'autre part sa relation avec la microstructure. Nous présenterons successivement : 1. L'incidence de modifications microstructurales sur les valeurs de j_c et ρ_{300}, 2. les mesures expérimentales de j_c, 3. la présence de phases minoritaires et de carbonates, 4. la reprise d'oxygène et la microfissuration, 5. la déformation plastique et les défauts structuraux associés.

Rebirth of Rural America: Rural Migration in the Midwest.

ERIC Educational Resources Information Center

Sofranko, Andrew J., Ed.; Williams, James D., Ed.

The trend reversing the massive nonmetropolitan-to-metropolitan migration of the past several decades is documented in this volume which is divided into three parts. Part I provides insights into several aspects of the new migration trend in the North Central Region of the U.S. The primary emphasis is on metropolitan origin migrants. Survey…

Effects of Didymosphenia geminata massive growth on stream communities: Smaller organisms and simplified food web structure

PubMed Central

Gomà, Joan; Prat, Narcís

2018-01-01

This study aims to contribute to the understanding of the impact of Didymosphenia geminata massive growths upon river ecosystem communities’ composition and functioning. This is the first study to jointly consider the taxonomic composition and functional structure of diatom and macroinvertebrate assemblages in order to determine changes in community structure, and the food web alterations associated with this invasive alga. This study was carried out in the Lumbreras River (Ebro Basin, La Rioja, Northern Spain), which has been affected by a considerable massive growth of D. geminata since 2011. The study shows a profound alteration in both the river community composition and in the food web structure at the sites affected by the massive growth, which is primarily due to the alteration of the environmental conditions, thus demonstrating that D. geminata has an important role as an ecosystem engineer in the river. Thick filamentous mats impede the movement of large invertebrates—especially those that move and feed up on it—and favor small, opportunistic, herbivorous organisms, mainly chironomids, that are capable of moving between filaments and are aided by the absence of large trophic competitors and predators -prey release effect-. Only small predators, such as hydra, are capable of surviving in the new environment, as they are favored by the increase in chironomids, a source of food, and by the reduction in both their own predators and other midge predators -mesopredator release-. This change in the top-down control affects the diatom community, since chironomids may feed on large diatoms, increasing the proportion of small diatoms in the substrate. The survival of small and fast-growing pioneer diatoms is also favored by the mesh of filaments, which offers them a new habitat for colonization. Simultaneously, D. geminata causes a significant reduction in the number of diatoms with similar ecological requirements (those attached to the substrate). Overall, D. geminata creates a community dominated by small organisms that is clearly different from the existing communities in the same stream where there is an absence of massive growths. PMID:29494699

Verification and recovery of thick deposits of massive gas hydrate from chimney structures, eastern margin of Japan Sea

NASA Astrophysics Data System (ADS)

Matsumoto, R.; Kakuwa, Y.; Snyder, G. T.; Tanahashi, M.; Yanagimoto, Y.; Morita, S.

2016-12-01

The initial scientific research that was carried out between 2004 and 2013 has provided us with invaluable evidence that gas hydrates occur widely on and below the sea floor down to approximately 30 mbsf within gas chimney structures in Japan Sea (Matsumoto, 2005; 2009). In 2013, METI (Ministry of Economy, Trade and Industry) launched a 3-year exploration project to assess the resource potential of shallow gas hydrates in Japan Sea. During the course of the project, Meiji University and AIST conducted: sea-going geophysical surveys with AUV, and high resolution 3D seismic and CSEM. These were followed by LWD and coring down to BSR depths, and coupled with a number of analyses and experiments. Regional mapping by MBES and SBP has confirmed 1742 gas chimneys in an area of 64,000km2 along the eastern margin of Japan Sea and around Hokkaido. Multiple LWD operations have revealed anomalous profiles such as extremely low natural gamma ray, high velocity Vp, and high resistivity Ro down to BSR depths, providing a strong indication that thick and massive gas hydrates exist throughout gas chimneys above the BSR. In several cases, conventional coring using 6-m long core liners recovered nearly 6 m long massive gas hydrates in several horizons adjacent to the anomalous LWD sites.The PCTB pressure coring system (Geotek Ltd) successfully cored 2-m long intervals of undisturbed, pressurized hydrate-bearing cores, providing valuable information about the in-situ occurrence and textural relations of hydrate and surrounding sediments. Full dissociation and slow degassing experiments of pressurized cores were conducted using onboard PCATS (Pressure core analysis and transfer system) to measure the amount of gases from hydrates. The mean volume fraction of gas hydrates in well-developed gas chimney structures is estimated to be 30 to 86 vol.% based on coupled PCATS and chloride anomaly profiles. Such an unusually high accumulation of gas hydrates in gas chimneys is assumed to have been caused by high TOC accumulation in rifted basins, followed by enhanced thermal maturation by high heat flow of young Japan Sea and, the subsequent migration of deep seated thermogenic gases as a consequence of the tectonic inversion some million years ago. This study was conducted under the commission from AIST as a part of the methane hydrate project of METI.

The Number Density of Quiescent Compact Galaxies at Intermediate Redshift

NASA Astrophysics Data System (ADS)

Damjanov, Ivana; Hwang, Ho Seong; Geller, Margaret J.; Chilingarian, Igor

2014-09-01

Massive compact systems at 0.2 < z < 0.6 are the missing link between the predominantly compact population of massive quiescent galaxies at high redshift and their analogs and relics in the local volume. The evolution in number density of these extreme objects over cosmic time is the crucial constraining factor for the models of massive galaxy assembly. We select a large sample of ~200 intermediate-redshift massive compacts from the Baryon Oscillation Spectroscopic Survey (BOSS) spectroscopy by identifying point-like Sloan Digital Sky Survey photometric sources with spectroscopic signatures of evolved redshifted galaxies. A subset of our targets have publicly available high-resolution ground-based images that we use to augment the dynamical and stellar population properties of these systems by their structural parameters. We confirm that all BOSS compact candidates are as compact as their high-redshift massive counterparts and less than half the size of similarly massive systems at z ~ 0. We use the completeness-corrected numbers of BOSS compacts to compute lower limits on their number densities in narrow redshift bins spanning the range of our sample. The abundance of extremely dense quiescent galaxies at 0.2 < z < 0.6 is in excellent agreement with the number densities of these systems at high redshift. Our lower limits support the models of massive galaxy assembly through a series of minor mergers over the redshift range 0 < z < 2.

A dust-obscured massive maximum-starburst galaxy at a redshift of 6.34.

PubMed

Riechers, Dominik A; Bradford, C M; Clements, D L; Dowell, C D; Pérez-Fournon, I; Ivison, R J; Bridge, C; Conley, A; Fu, Hai; Vieira, J D; Wardlow, J; Calanog, J; Cooray, A; Hurley, P; Neri, R; Kamenetzky, J; Aguirre, J E; Altieri, B; Arumugam, V; Benford, D J; Béthermin, M; Bock, J; Burgarella, D; Cabrera-Lavers, A; Chapman, S C; Cox, P; Dunlop, J S; Earle, L; Farrah, D; Ferrero, P; Franceschini, A; Gavazzi, R; Glenn, J; Solares, E A Gonzalez; Gurwell, M A; Halpern, M; Hatziminaoglou, E; Hyde, A; Ibar, E; Kovács, A; Krips, M; Lupu, R E; Maloney, P R; Martinez-Navajas, P; Matsuhara, H; Murphy, E J; Naylor, B J; Nguyen, H T; Oliver, S J; Omont, A; Page, M J; Petitpas, G; Rangwala, N; Roseboom, I G; Scott, D; Smith, A J; Staguhn, J G; Streblyanska, A; Thomson, A P; Valtchanov, I; Viero, M; Wang, L; Zemcov, M; Zmuidzinas, J

2013-04-18

Massive present-day early-type (elliptical and lenticular) galaxies probably gained the bulk of their stellar mass and heavy elements through intense, dust-enshrouded starbursts--that is, increased rates of star formation--in the most massive dark-matter haloes at early epochs. However, it remains unknown how soon after the Big Bang massive starburst progenitors exist. The measured redshift (z) distribution of dusty, massive starbursts has long been suspected to be biased low in z owing to selection effects, as confirmed by recent findings of systems with redshifts as high as ~5 (refs 2-4). Here we report the identification of a massive starburst galaxy at z = 6.34 through a submillimetre colour-selection technique. We unambiguously determined the redshift from a suite of molecular and atomic fine-structure cooling lines. These measurements reveal a hundred billion solar masses of highly excited, chemically evolved interstellar medium in this galaxy, which constitutes at least 40 per cent of the baryonic mass. A 'maximum starburst' converts the gas into stars at a rate more than 2,000 times that of the Milky Way, a rate among the highest observed at any epoch. Despite the overall downturn in cosmic star formation towards the highest redshifts, it seems that environments mature enough to form the most massive, intense starbursts existed at least as early as 880 million years after the Big Bang.

Exact solutions of massive gravity in three dimensions

NASA Astrophysics Data System (ADS)

Chakhad, Mohamed

In recent years, there has been an upsurge in interest in three-dimensional theories of gravity. In particular, two theories of massive gravity in three dimensions hold strong promise in the search for fully consistent theories of quantum gravity, an understanding of which will shed light on the problems of quantum gravity in four dimensions. One of these theories is the "old" third-order theory of topologically massive gravity (TMG) and the other one is a "new" fourth-order theory of massive gravity (NMG). Despite this increase in research activity, the problem of finding and classifying solutions of TMG and NMG remains a wide open area of research. In this thesis, we provide explicit new solutions of massive gravity in three dimensions and suggest future directions of research. These solutions belong to the Kundt class of spacetimes. A systematic analysis of the Kundt solutions with constant scalar polynomial curvature invariants provides a glimpse of the structure of the spaces of solutions of the two theories of massive gravity. We also find explicit solutions of topologically massive gravity whose scalar polynomial curvature invariants are not all constant, and these are the first such solutions. A number of properties of Kundt solutions of TMG and NMG, such as an identification of solutions which lie at the intersection of the full nonlinear and linearized theories, are also derived.

Resilience of branching and massive corals to wave loading under sea level rise--a coupled computational fluid dynamics-structural analysis.

PubMed

Baldock, Tom E; Karampour, Hassan; Sleep, Rachael; Vyltla, Anisha; Albermani, Faris; Golshani, Aliasghar; Callaghan, David P; Roff, George; Mumby, Peter J

2014-09-15

Measurements of coral structural strength are coupled with a fluid dynamics-structural analysis to investigate the resilience of coral to wave loading under sea level rise and a typical Great Barrier Reef lagoon wave climate. The measured structural properties were used to determine the wave conditions and flow velocities that lead to structural failure. Hydrodynamic modelling was subsequently used to investigate the type of the bathymetry where coral is most vulnerable to breakage under cyclonic wave conditions, and how sea level rise (SLR) changes this vulnerability. Massive corals are determined not to be vulnerable to wave induced structural damage, whereas branching corals are susceptible at wave induced orbital velocities exceeding 0.5m/s. Model results from a large suite of idealised bathymetry suggest that SLR of 1m or a loss of skeleton strength of order 25% significantly increases the area of reef flat where branching corals are exposed to damaging wave induced flows. Copyright © 2014 Elsevier Ltd. All rights reserved.

Unsupervised Learning Through Randomized Algorithms for High-Volume High-Velocity Data (ULTRA-HV).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pinar, Ali; Kolda, Tamara G.; Carlberg, Kevin Thomas

Through long-term investments in computing, algorithms, facilities, and instrumentation, DOE is an established leader in massive-scale, high-fidelity simulations, as well as science-leading experimentation. In both cases, DOE is generating more data than it can analyze and the problem is intensifying quickly. The need for advanced algorithms that can automatically convert the abundance of data into a wealth of useful information by discovering hidden structures is well recognized. Such efforts however, are hindered by the massive volume of the data and its high velocity. Here, the challenge is developing unsupervised learning methods to discover hidden structure in high-volume, high-velocity data.

Three dimensional magnetic solutions in massive gravity with (non)linear field

NASA Astrophysics Data System (ADS)

Hendi, S. H.; Eslam Panah, B.; Panahiyan, S.; Momennia, M.

2017-12-01

The Noble Prize in physics 2016 motivates one to study different aspects of topological properties and topological defects as their related objects. Considering the significant role of the topological defects (especially magnetic strings) in cosmology, here, we will investigate three dimensional horizonless magnetic solutions in the presence of two generalizations: massive gravity and nonlinear electromagnetic field. The effects of these two generalizations on properties of the solutions and their geometrical structure are investigated. The differences between de Sitter and anti de Sitter solutions are highlighted and conditions regarding the existence of phase transition in geometrical structure of the solutions are studied.

Peering into the heart of galactic star formation: A detailed characterization of infrared-dark clouds

NASA Astrophysics Data System (ADS)

Ragan, Sarah E.

2009-09-01

Everything we know about other galaxies is based on light from massive stars, yet, in our own Galaxy, it's the formation of massive stars that is the least understood. Star formation studies to date have focused on nearby, low-mass regions, but the bulk of star formation takes place in massive clusters, which takes place primarily in the inner-Galaxy, where the bulk of the molecular gas resides. To learn about the conditions under which massive clusters form, we seek out their precursors, called infrared-dark clouds (IRDCs). We present the results of a high-resolution multi-wavelength observational study of IRDCs, which vastly improves our knowledge of the initial conditions of cluster formation. Beginning with IRDC candidates identified with Midcourse Science Experiment (MSX) survey data, we map 41 IRDCs in the N 2 H + 1 [arrow right] 0, CS 2 [arrow right] 1 and C 18 O 1 [arrow right] 0 molecular transitions using the Five College Radio Astronomy Observatory. We examine the stellar content and absorption structure with Spitzer Space Telescope observations of eleven IRDCs, and we use Very Large Array NH 3 observations to probe the kinematics and chemistry of six IRDCs. Our comprehensive high-resolution study of IRDCs confirms that these objects are cold and dense precursors to massive stars and clusters. For the first time. we quantify IRDC sub-structure on sub-parsec scales and show the kinematic structure of IRDCs is diverse and depends on associated local star- formation activity. Overall, IRDCs exhibit non-thermal dynamics, suggesting that turbulence and systematic motions dominate. IRDC temperatures are between 8 and 16 K and are mostly flat with hints of a rise near the edges due to external heating. This study shows that IRDCs are a unique star-forming environment, one that dominates the star formation in the Milky Way. Using high-resolution observations, we have quantified the structure, star formation, kinematics, and chemistry of infrared-dark clouds. Our study of sub- structure in particular shows that IRDCs are undergoing fragmentation and are the precursors to star clusters, and thus we have placed IRDCs in context with Galactic star formation. The characterization presented here offers new constraints on theories of molecular cloud fragmentation and clustered star formation.

Spontaneous scalarization with an extremely massive field and heavy neutron stars

NASA Astrophysics Data System (ADS)

Morisaki, Soichiro; Suyama, Teruaki

2017-10-01

We investigate the internal structure and the mass-radius relation of neutron stars in a recently proposed scalar-tensor theory dubbed asymmetron in which a massive scalar field undergoes spontaneous scalarization inside neutron stars. We focus on the case where the Compton wavelength is shorter than 10 km, which has not been investigated in the literature. By solving the modified Einstein equations, either purely numerically or by partially using a semianalytic method, we find that not only the weakening of gravity by spontaneous scalarization but also the scalar force affect the internal structure significantly in the massive case. We also find that the maximum mass of neutron stars is larger for certain parameter sets than that in general relativity and reaches 2 M⊙ even if the effect of strange hadrons is taken into account. There is even a range of parameters where the maximum mass of neutron stars largely exceeds the threshold that violates the causality bound in general relativity.

Galaxy evolution. Quasar quartet embedded in giant nebula reveals rare massive structure in distant universe.

PubMed

Hennawi, Joseph F; Prochaska, J Xavier; Cantalupo, Sebastiano; Arrigoni-Battaia, Fabrizio

2015-05-15

All galaxies once passed through a hyperluminous quasar phase powered by accretion onto a supermassive black hole. But because these episodes are brief, quasars are rare objects typically separated by cosmological distances. In a survey for Lyman-α emission at redshift z ≈ 2, we discovered a physical association of four quasars embedded in a giant nebula. Located within a substantial overdensity of galaxies, this system is probably the progenitor of a massive galaxy cluster. The chance probability of finding a quadruple quasar is estimated to be ∼10(-7), implying a physical connection between Lyman-α nebulae and the locations of rare protoclusters. Our findings imply that the most massive structures in the distant universe have a tremendous supply (≃10(11) solar masses) of cool dense (volume density ≃ 1 cm(-3)) gas, which is in conflict with current cosmological simulations. Copyright © 2015, American Association for the Advancement of Science.

Efficient discovery of overlapping communities in massive networks

PubMed Central

Gopalan, Prem K.; Blei, David M.

2013-01-01

Detecting overlapping communities is essential to analyzing and exploring natural networks such as social networks, biological networks, and citation networks. However, most existing approaches do not scale to the size of networks that we regularly observe in the real world. In this paper, we develop a scalable approach to community detection that discovers overlapping communities in massive real-world networks. Our approach is based on a Bayesian model of networks that allows nodes to participate in multiple communities, and a corresponding algorithm that naturally interleaves subsampling from the network and updating an estimate of its communities. We demonstrate how we can discover the hidden community structure of several real-world networks, including 3.7 million US patents, 575,000 physics articles from the arXiv preprint server, and 875,000 connected Web pages from the Internet. Furthermore, we demonstrate on large simulated networks that our algorithm accurately discovers the true community structure. This paper opens the door to using sophisticated statistical models to analyze massive networks. PMID:23950224

Highlights of Astronomy, Vol. 16

NASA Astrophysics Data System (ADS)

Montmerle, Thierry

2015-04-01

Part I. Invited Discourses: 1. The Herschel view of star formation; 2. Past, present and future of Chinese astronomy; 3. The zoo of galaxies; 4. Supernovae, the accelerating cosmos, and dark energy; Part II. Joint Discussion: 5. Very massive stars in the local universe; 6. 3-D views of the cycling Sun in stellar context; 7. Ultraviolet emission in early-type galaxies; 8. From meteors and meteorites to their parent bodies: current status and future developments; 9. The connection between radio properties and high-energy emission in AGNs; 10. Space-time reference systems for future research; Part III. Special Sessions: 11. Origin and complexity of massive star clusters; 12. Cosmic evolution of groups and clusters of galaxies; 13. Galaxy evolution through secular processes; 14. New era for studying interstellar and intergalactic magnetic fields; 15. The IR view of massive stars: the main sequence and beyond; 16. Science with large solar telescopes; 17. The impact hazard: current activities and future plans; 18. Calibration of star-formation rate measurements across the electromagnetic spectrum; 19. Future large scale facilities; 20. Dynamics of the star-planet relations strategic plan and the Global Office of Astronomy for Development; 21. Strategic plan and the Global Office of Astronomy for Development; 22. Modern views of the interstellar medium; 23. High-precision tests of stellar physics from high-precision photometry; 24. Communicating astronomy with the public for scientists; 25. Data intensive astronomy; 26. Unexplained spectral phenomena in the interstellar medium; 27. Light pollution: protecting astronomical sites and increasing global awareness through education.

CHEMICAL DIAGNOSTICS OF THE MASSIVE STAR CLUSTER-FORMING CLOUD G33.92+0.11. I. {sup 13}CS, CH{sub 3}OH, CH{sub 3}N, OCS, H{sub 2}S, SO{sub 2}, and SiO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Minh, Young Chol; Liu, Hauyu Baobab; Galvań-Madrid, Roberto

2016-06-20

Large chemical diversity was found in the gas clumps associated with the massive star cluster-forming G33.92+0.11 region with sub-arcsecond angular resolution (0.″6–0.″8) observations with ALMA. The most prominent gas clumps are associated with the dust emission peaks A1, A2, and A5. The close correlation between CH{sub 3}OH and OCS in the emission distributions strongly suggests that these species share a common origin of hot core grain mantle evaporation. The latest generation of star clusters are forming in the A5 clump, as indicated by multiple SiO outflows and its rich hot core chemistry. We also found a narrow SiO emission associatedmore » with the outflows, which may trace a cooled component of the outflows. Part of the chemical complexity may have resulted from the accreting gas from the ambient clouds, especially in the northern part of A1 and the southern part of A2. The chemical diversity found in this region is believed to mainly result from the different chemical evolutionary timescales of massive star formation. In particular, the abundance ratio between CH{sub 3}OH and CH{sub 3}CN may be a good chemical clock for the early phase of star formation.« less

DEMNUni: massive neutrinos and the bispectrum of large scale structures

NASA Astrophysics Data System (ADS)

Ruggeri, Rossana; Castorina, Emanuele; Carbone, Carmelita; Sefusatti, Emiliano

2018-03-01

The main effect of massive neutrinos on the large-scale structure consists in a few percent suppression of matter perturbations on all scales below their free-streaming scale. Such effect is of particular importance as it allows to constraint the value of the sum of neutrino masses from measurements of the galaxy power spectrum. In this work, we present the first measurements of the next higher-order correlation function, the bispectrum, from N-body simulations that include massive neutrinos as particles. This is the simplest statistics characterising the non-Gaussian properties of the matter and dark matter halos distributions. We investigate, in the first place, the suppression due to massive neutrinos on the matter bispectrum, comparing our measurements with the simplest perturbation theory predictions, finding the approximation of neutrinos contributing at quadratic order in perturbation theory to provide a good fit to the measurements in the simulations. On the other hand, as expected, a linear approximation for neutrino perturbations would lead to Script O(fν) errors on the total matter bispectrum at large scales. We then attempt an extension of previous results on the universality of linear halo bias in neutrino cosmologies, to non-linear and non-local corrections finding consistent results with the power spectrum analysis.

First Spectroscopic Identification of Massive Young Stellar Objects in the Galactic Center

NASA Technical Reports Server (NTRS)

An, Deokkeun; Ramirez, V.; Sellgren, Kris; Arendt, Richard G.; Boogert, A. C.; Schultheis, Mathias; Stolovy, Susan R.; Cotera, Angela S.; Robitaille, Thomas P.; Smith, Howard A.

2009-01-01

We report the detection of several molecular gas-phase and ice absorption features in three photometrically-selected young stellar object (YSO) candidates in the central 280 pc of the Milky Way. Our spectra, obtained with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, reveal gas-phase absorption from CO2 (15.0 microns), C2H2 (13.7 microns) and HCN (14.0 microns). We attribute this absorption to warm, dense gas in massive YSOs. We also detect strong and broad 15 microns CO2 ice absorption features, with a remarkable double-peaked structure. The prominent long-wavelength peak is due to CH3OH-rich ice grains, and is similar to those found in other known massive YSOs. Our IRS observa.tions demonstra.te the youth of these objects, and provide the first spectroscopic identification of massive YSOs in the Galactic Center.

Traumatic dissection of extracranial vertebral artery with massive subtentorial cerebral infarction: report of an autopsy case.

PubMed

Saito, Kazuyuki; Takada, Aya; Kuroda, Naohito; Hara, Masaaki; Arai, Masaaki; Ro, Ayako

2009-04-01

We present an extremely rare autopsy case with traumatic dissection of the extracranial vertebral artery due to blunt injury caused by a traffic accident. The patient complained of nausea and numbness of the hands at the scene of the accident. His consciousness deteriorated and he fell into a coma within 12h, then died 4 days after the collision. Brain CT/MRI disclosed massive infratentorial cerebral infarction while MRA imaged neither of the vertebral arteries. Autopsy revealed a seatbelt mark on the right side of the lower neck, with fracture of the right transverse process of the sixth cervical vertebra. The right extracranial vertebral artery (V2) showed massive medial dissection from the portion adjacent to the fracture throughout the upper end of the extracranial part of the artery and was occluded by a thrombus. An intimal tear was confirmed near the starting point of the dissection. The brain disclosed massive infarction of posterior circulation territories with changes to the so-called respirator brain. The victim's left vertebral artery was considerably hypoplastic. We concluded that a massive infratentorial infarction was caused by dissection of the right extracranial vertebral artery and consecutive thrombus formation brought about by impact with the seatbelt at the time of the collision.

a UV Spectral Library of Metal-Poor Massive Stars

NASA Astrophysics Data System (ADS)

Robert, Carmelle

1994-01-01

We propose to use the FOS to build a snapshot library of UV spectra of a sample of about 50 metal-poor massive stars located in the Magellanic Clouds. The majority of libraries already existing contains spectra of hot stars with chemical abundances close to solar. The high spectral resolution achieves with the FOS will be a major factor for the uniqueness of this new library. UV spectral libraries represent fundamental tools for the study of the massive star populations of young star-forming regions. Massive stars, which are impossible to identify directly in the optical-IR part of a composite spectrum, display on the other hand key signatures in the UV region. These signatures are mainly broad, metallicity dependent spectral features formed in the hot star winds. They require a high spectral resolution (of the order of 200-300 km/s) for an adequate study. A spectral library of metal-poor massive stars represents also a unique source of data for a stellar atmosphere analysis. Within less then 10 min we will obtain a high signal-to-noise ratio of at least 30. Finally, since short exposure times are possible, this proposal makes extremely good use of the capabilities of HST. We designed an observing strategy which yields a maximum scientific return at a minimum cost of spacecraft time.

[Progress of Masquelet technique to repair bone defect].

PubMed

Yin, Qudong; Sun, Zhenzhong; Gu, Sanjun

2013-10-01

To summarize the progress of Masquelet technique to repair bone defect. The recent literature concerning the application of Masquelet technique to repair bone defect was extensively reviewed and summarized. Masquelet technique involves a two-step procedure. First, bone cement is used to fill the bone defect after a thorough debridement, and an induced membrane structure surrounding the spacer formed; then the bone cement is removed after 6-8 weeks, and rich cancellous bone is implanted into the induced membrane. Massive cortical bone defect is repaired by new bone forming and consolidation. Experiments show that the induced membrane has vascular system and is also rich in vascular endothelial growth factor, transforming growth factor beta1, bone morphogenetic protein 2, and bone progenitor cells, so it has osteoinductive property; satisfactory results have been achieved in clinical application of almost all parts of defects, various types of bone defect and massive defect up to 25 cm long. Compared with other repair methods, Masquelet technique has the advantages of reliable effect, easy to operate, few complications, low requirements for recipient site, and wide application. Masquelet technique is an effective method to repair bone defect and is suitable for various types of bone defect, especially for bone defects caused by infection and tumor resection.

Hubble Sees A Smiling Lens

NASA Image and Video Library

2015-02-10

In the center of this image, taken with the NASA/ESA Hubble Space Telescope, is the galaxy cluster SDSS J1038+4849 — and it seems to be smiling. You can make out its two orange eyes and white button nose. In the case of this “happy face”, the two eyes are very bright galaxies and the misleading smile lines are actually arcs caused by an effect known as strong gravitational lensing. Galaxy clusters are the most massive structures in the Universe and exert such a powerful gravitational pull that they warp the spacetime around them and act as cosmic lenses which can magnify, distort and bend the light behind them. This phenomenon, crucial to many of Hubble’s discoveries, can be explained by Einstein’s theory of general relativity. In this special case of gravitational lensing, a ring — known as an Einstein Ring — is produced from this bending of light, a consequence of the exact and symmetrical alignment of the source, lens and observer and resulting in the ring-like structure we see here. Hubble has provided astronomers with the tools to probe these massive galaxies and model their lensing effects, allowing us to peer further into the early Universe than ever before. This object was studied by Hubble’s Wide Field and Planetary Camera 2 (WFPC2) and Wide Field Camera 3 (WFC3) as part of a survey of strong lenses. A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt. Image Credit: NASA/ESA

Effect of Ground Motion Characteristics on the Seismic Response of a Monumental Concrete Arch Bridge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caglayan, B. Ozden; Ozakgul, Kadir; Tezer, Ovunc

2008-07-08

Railway network in Turkey dates back to more than a hundred years ago and according to official records, there are approximately 18,000 railway bridges with spans varying between 50 cm up to 150 meters. One of them is a monumental concrete arch bridge with a total length of 210 meters having three major spans of 30 meters and a height of 65 meters, located in an earthquake-prone region in southern part of the country. Three-dimensional finite element model of the bridge was generated using a commercially available general finite element analysis software and based on the outcomes of a seriesmore » of in-depth acceleration measurements that were conducted on-site, the model was refined. Types of ground motion records were used to investigate the seismic response and vulnerability of this massive structure in order to provide information regarding (i) damage-susceptible regions of the structure for monitoring purposes, and, (ii) seismic loads to be taken into account during evaluation and possible strengthening phases for this type of structures.« less

Analysis of interstellar cloud structure based on IRAS images

NASA Technical Reports Server (NTRS)

Scalo, John M.

1992-01-01

The goal of this project was to develop new tools for the analysis of the structure of densely sampled maps of interstellar star-forming regions. A particular emphasis was on the recognition and characterization of nested hierarchical structure and fractal irregularity, and their relation to the level of star formation activity. The panoramic IRAS images provided data with the required range in spatial scale, greater than a factor of 100, and in column density, greater than a factor of 50. In order to construct densely sampled column density maps of star-forming clouds, column density images of four nearby cloud complexes were constructed from IRAS data. The regions have various degrees of star formation activity, and most of them have probably not been affected much by the disruptive effects of young massive stars. The largest region, the Scorpius-Ophiuchus cloud complex, covers about 1000 square degrees (it was subdivided into a few smaller regions for analysis). Much of the work during the early part of the project focused on an 80 square degree region in the core of the Taurus complex, a well-studied region of low-mass star formation.

The Physical Environment around IRAS 17599-2148: Infrared Dark Cloud and Bipolar Nebula

NASA Astrophysics Data System (ADS)

Dewangan, L. K.; Ojha, D. K.; Zinchenko, I.; Janardhan, P.; Ghosh, S. K.; Luna, A.

2016-12-01

We present a multiscale and multiwavelength study to investigate the star formation process around IRAS 17599-2148, which is part of an elongated filamentary structure (EFS) (extension ˜21 pc) seen in the Herschel maps. Using the Herschel data analysis, at least six massive clumps (M clump ˜ 777-7024 M ⊙) are found in the EFS with a range of temperature and column density of ˜16-39 K and ˜(0.6-11) × 1022 cm-2 (A V ˜ 7-117 mag), respectively. The EFS hosts cold gas regions (I.e., infrared dark cloud) without any radio detection and a bipolar nebula (BN) linked with the H II region IRAS 17599-2148, tracing two distinct environments inferred through the temperature distribution and ionized emission. Based on virial analysis and higher values of self-gravitating pressure, the clumps are found unstable against gravitational collapse. We find 474 young stellar objects (YSOs) in the selected region, and ˜72% of these YSOs are found in the clusters distributed mainly toward the clumps in the EFS. These YSOs might have spontaneously formed due to processes not related to the expanding H II region. At the edges of BN, four additional clumps are also associated with YSO clusters, which appear to be influenced by the expanding H II region. The most massive clump in the EFS contains two compact radio sources traced in the Giant Metre-wave Radio Telescope 1.28 GHz map and a massive protostar candidate, IRS 1, prior to an ultracompact H II phase. Using the Very Large Telescope/NACO near-infrared images, IRS 1 is resolved with a jet-like feature within a 4200 au scale.

The role of intermediate filaments in maintaining integrity and function of intestinal epithelial cells after massive bowel resection in a rat.

PubMed

Sukhotnik, I; Shahar, Y Ben; Pollak, Y; Dorfman, T; Shefer, H Kreizman; Assi, Z E; Mor-Vaknin, N; Coran, A G

2018-02-01

Intermediate filaments (IFs) are a part of the cytoskeleton that extend throughout the cytoplasm of all cells and function in the maintenance of cell-shape by bearing tension and serving as structural components of the nuclear lamina. In normal intestine, IFs provide a tissue-specific three-dimensional scaffolding with unique context-dependent organizational features. The purpose of this study was to evaluate the role of IFs during intestinal adaptation in a rat model of short bowel syndrome (SBS). Male rats were divided into two groups: Sham rats underwent bowel transection and SBS rats underwent a 75% bowel resection. Parameters of intestinal adaptation, enterocyte proliferation and apoptosis were determined 2 weeks after operation. Illumina's Digital Gene Expression (DGE) analysis was used to determine the cytoskeleton-related gene expression profiling. IF-related genes and protein expression were determined using real-time PCR, Western blotting and immunohistochemistry. Massive small bowel resection resulted in a significant increase in enterocyte proliferation and concomitant increase in cell apoptosis. From the total number of 20,000 probes, 16 cytoskeleton-related genes were investigated. Between these genes, only myosin and tubulin levels were upregulated in SBS compared to sham animals. Between IF-related genes, desmin, vimentin and lamin levels were down-regulated and keratin and neurofilament remain unchanged. The levels of TGF-β, vimentin and desmin gene and protein were down-regulated in resected rats (vs sham animals). Two weeks following massive bowel resection in rats, the accelerated cell turnover was accompanied by a stimulated microfilaments and microtubules, and by inhibited intermediate filaments. Resistance to cell compression rather that maintenance of cell-shape by bearing tension are responsible for contraction, motility and postmitotic cell separation in a late stage of intestinal adaptation.

Cerro de Pasco and other massive sulfide deposits of central Peru

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheney, E.S.

1985-01-01

The famous Cerro de Pasco Pb-Zn-Ag deposit historically has been considered to be hydrothermally derived from an adjacent Tertiary volcanic vent. However, texturally massive pyrite-chert and pyrite-sphalerite-galena in the deposit have the same strike and cross folds as the adjacent pre-Tertiary strata. Both the deposit and the strata are cut by one of the large Longitudinal Faults. Both dikes and pyrite-enargite veins associated with the vent cut the massive sulfides; fragments of massive pyrite occur in the vent. A few examples of laminated pyrite and chert, banded pyrite and chert, banded pyrite and sphalerite, and banded pyrite, sphalerite, and galenamore » are preserved in the massive sulfide portion of the deposit. The deposit has the composition and zoning patterns typical of shale-hosted massive sulfides. Cerro de Pasco probably in part of the pelitic Devonian Excelsior formation. The Colquijirca deposit 8 km to the south and the San Cristobal district 110 km to the south likewise have been considered to be Tertiary volcanic hydrothermal deposits. Colquijirca consists of stratigraphically controlled mantos of layered pyrite, chert and tuff in the Tertiary Calera formation. The mantos of the San Cristobal district are along the upper contact of the pyritic, Permian, Catalina felsic volcanic rocks; some ore consists of laminated pyrite and sphalerite. Tertiary plutons are conspicuously absent at San Cristobal, and the ores are brecciated by Tertiary folding.« less

Two new confirmed massive relic galaxies: red nuggets in the present-day Universe

NASA Astrophysics Data System (ADS)

Ferré-Mateu, Anna; Trujillo, Ignacio; Martín-Navarro, Ignacio; Vazdekis, Alexandre; Mezcua, Mar; Balcells, Marc; Domínguez, Lilian

2017-05-01

We confirm two new local massive relic galaxies, I.e. untouched survivors of the early Universe massive population: Mrk 1216 and PGC 032873. Both show early and peaked formation events within very short time-scales (<1 Gyr) and thus old mean mass-weighted ages (˜13 Gyr). Their star formation histories remain virtually unchanged out to several effective radii, even when considering the steeper initial-mass-function values inferred out to ˜3 effective radii. Their morphologies, kinematics and density profiles are like those found in the z > 2 massive population, setting them apart from the typical z ˜ 0 massive early-type galaxies. We find that there seems to exist a degree of relic that is related to how far into the path, to become one of these typical z ˜ 0 massive galaxies, the compact relic has moved. This path is partly dictated by the environment the galaxy lives in. For galaxies in rich environments, such as the previously reported relic galaxy NGC 1277, the most extreme properties (e.g. sizes, short formation time-scales, larger supermassive black holes) are expected, while lower density environments will have galaxies with delayed and/or extended star formations, slightly larger sizes and not that extreme black hole masses. The confirmation of three relic galaxies up to a distance of 106 Mpc, implies a lower limit in the number density of these red nuggets in the local Universe of 6 × 10-7 Mpc3, which is within the theoretical expectations.

Highly diverse, massive organic data as explored by a composite QSPR strategy: an advanced study of boiling point.

PubMed

Ivanova, A A; Ivanov, A A; Oliferenko, A A; Palyulin, V A; Zefirov, N S

2005-06-01

An improved strategy of quantitative structure-property relationship (QSPR) studies of diverse and inhomogeneous organic datasets has been proposed. A molecular connectivity term was successively corrected for different structural features encoded in fragmental descriptors. The so-called solvation index 1chis (a weighted Randic index) was used as a "leading" variable and standardized molecular fragments were employed as "corrective" class-specific variables. Performance of the new approach was illustrated by modelling a dataset of experimental normal boiling points of 833 organic compounds belonging to 20 structural classes. Firstly, separate QSPR models were derived for each class and for eight groups of structurally similar classes. Finally, a general model formed by combining all the classes together was derived (r2=0.957, s=12.9degreesC). The strategy outlined can find application in QSPR analyses of massive, highly diverse databases of organic compounds.

Dimensional reduction as a method to obtain dual theories for massive spin two in arbitrary dimensions

NASA Astrophysics Data System (ADS)

Khoudeir, A.; Montemayor, R.; Urrutia, Luis F.

2008-09-01

Using the parent Lagrangian method together with a dimensional reduction from D to (D-1) dimensions, we construct dual theories for massive spin two fields in arbitrary dimensions in terms of a mixed symmetry tensor TA[A1A2…AD-2]. Our starting point is the well-studied massless parent action in dimension D. The resulting massive Stueckelberg-like parent actions in (D-1) dimensions inherit all the gauge symmetries of the original massless action and can be gauge fixed in two alternative ways, yielding the possibility of having a parent action with either a symmetric or a nonsymmetric Fierz-Pauli field eAB. Even though the dual sector in terms of the standard spin two field includes only the symmetrical part e{AB} in both cases, these two possibilities yield different results in terms of the alternative dual field TA[A1A2…AD-2]. In particular, the nonsymmetric case reproduces the Freund-Curtright action as the dual to the massive spin two field action in four dimensions.

Luminous Herbig-Haro objects from a massive protostar: The unique case of HH 80/81

NASA Astrophysics Data System (ADS)

Reipurth, Bo

2017-08-01

Herbig-Haro (HH) objects are the optical manifestations of shock waves excited by outflows from young stars. They represent one of the few classes of spatially extended astronomical objects where both structural changes and proper motions can be measured on time scales of years to decades. HH 80/81 is a pair of HH objects in Sagittarius which are the intrinsically most luminous HH objects known. The driving source of HH 80/81 is the embedded star IRAS 18162-2048, which has a luminosity of 20,000 Lsun and excites a compact HII region, suggesting that it is a newborn massive star. HH objects associated with massive young stars are very rare, only a handful of cases are known, but what makes the HH 80/81 source unique among massive protostars is that it produces a finely collimated bipolar radio jet with extremely high velocity and pointing straight to HH 80/81. We propose to observe the HH 80/81 complex with WFC3 and the following four filters: Halpha 6563, Hbeta 4861, [SII] 6717/31, and [OIII] 5007. First epoch HST images were obtained 22 years ago, which now allows a very precise determination of proper motions. Groundbased optical and radio proper motions are not only uncertain, but actually contradict each other, a controversy that will be resolved by HST. The fine resolution of WFC3 allows a study of both fine structural details and structural changes of the shocks. Finally we will use a sophisticated adaptive grid code to interpret the (de-reddened) line ratios across the shocks.

Comparison of Weather Shows in Eastern Europe

NASA Astrophysics Data System (ADS)

Najman, M.

2009-09-01

Comparison of Weather Shows in Eastern Europe Television weather shows in Eastern Europe have in most cases in the high graphical standard. There is though a wast difference in duration and information content in the weather shows. There are few signs and regularities by which we can see the character of the weather show. The main differences are mainly caused by the income structure of the TV station. Either it is a fully privately funded TV relying on the TV commercials income. Or it is a public service TV station funded mainly by the national budget or fixed fee structure/tax. There are wast differences in duration and even a graphical presentation of the weather. Next important aspect is a supplier of the weather information and /or the processor. Shortly we can say, that when the TV show is produced by the national met office, the TV show consists of more scientific terms, synoptic maps, satellite imagery, etc. If the supplier is the private meteorological company, the weather show is more user-friendly, laical with less scientific terms. We are experiencing a massive shift in public weather knowledge and demand for information. In the past, weather shows consisted only of maps with weather icons. In todaýs world, even the laic weather shows consist partly of numerical weather model outputs - they are of course designed to be understandable and graphically attractive. Outputs of the numerical weather models used to be only a part of daily life of a professional meteorologist, today they are common part of life of regular people. Video samples are a part of this presentation.

Sulphide mineralization and wall-rock alteration in ophiolites and modern oceanic spreading centres

USGS Publications Warehouse

Koski, R.A.

1983-01-01

Massive and stockwork Fe-Cu-Zn (Cyprus type) sulphide deposits in the upper parts of ophiolite complexes represent hydrothermal mineralization at ancient accretionary plate boundaries. These deposits are probable metallogenic analogues of the polymetallic sulphide deposits recently discovered along modern oceanic spreading centres. Genetic models for these deposits suggest that mineralization results from large-scale circulation of sea-water through basaltic basement along the tectonically active axis of spreading, a zone of high heat flow. The high geothermal gradient above 1 to 2 km deep magma chambers emplaced below the ridge axis drives the convective circulation cell. Cold oxidizing sea-water penetrating the crust on the ridge flanks becomes heated and evolves into a highly reduced somewhat acidic hydrothermal solvent during interaction with basaltic wall-rock. Depending on the temperature and water/rock ratio, this fluid is capable of leaching and transporting iron, manganese, and base metals; dissolved sea-water sulphate is reduced to sulphide. At the ridge axis, the buoyant hydrothermal fluid rises through permeable wall-rocks, and fluid flow may be focussed along deep-seated fractures related to extensional tectonic processes. Metal sulphides are precipitated along channelways as the ascending fluid undergoes adiabatic expansion and then further cooling during mixing with ambient sub-sea-floor water. Vigorous fluid flow results in venting of reduced fluid at the sea-floor/sea-water interface and deposition of massive sulphide. A comparison of sulphide mineralization and wall-rock alteration in ancient and modern spreading centre environments supports this genetic concept. Massive sulphide deposits in ophiolites generally occur in clusters of closely spaced (< 1-5 km) deposits. Individual deposits are a composite of syngenetic massive sulphide and underlying epigenetic stockwork-vein mineralization. The massive sulphide occurs as concordant tabular, lenticular, or saucer-shaped bodies in pillow lavas and pillow-lava breccia; massive lava flows, hyalcoclastite, tuff, and bedded radolarian chert are less commonly associated rock types. These massive sulphide zones are as much as 700 m long, 200 m wide, and 50 m thick. The pipe-, funnel-, or keel-shaped stockwork zone may extend to a dehpth of 1 km in the sheeted-dike complex. Several deposits in Cyprus are confined to grabens or the hanging wall of premineralization normal faults. Polymetallic massive sulphide deposits and active hydrothermal vents at medium- to fast-rate spreading centres (the East Pacific Rise at lat. 21??N, the Galapagos Spreading Centre at long. 86??W, the Juan de Fuca Ridge at lat. 45??N., and the Southern Trough of Guaymas Basin, Gulf of California) have interdeposit spacings on a scale of tens or hundreds of metres, and are spatially associated with structural ridges or grabens within the narrow (< 5 km) axial valleys of the rift zones. Although the most common substrate for massive sulphide accumulations is stacked sequences of pillow basalt and sheet flows, the sea-floor underlying numerous deposits in Guaymas Basin consists of diatomaceous ooze and terrigenous clastic sediment that is intruded by diabase sills. Mound-like massive sulphide deposits, as much as 30 m wide and 5m high, occur over actively discharging vents on the East Pacific Rise, and many of these deposits serve as the base for narrow chimneys and spires of equal or greater height. Sulphides on the Juan de Fuca Ridge appear to form more widespread blanket deposits in the shallow axial-valley depression. The largest deposit found to date, along the axial ridge of the Galapagos Spreading Centre, has a tabular form and a length of 1000 m, a width of 200 m, and a height of 30 m. The sulphide assemblage in both massive and vein mineralization in Cyprus type deposits is characteristically simple: abundant pyrite or, less commonly, pyrrhotite accompanied by minor marcasite, chalcopyrite

The Massive Compound Cofre de Perote Shield Volcano: a Volcanological Oddity in the Eastern Mexican Volcanic Belt

NASA Astrophysics Data System (ADS)

Siebert, L.; Carrasco-Nunez, G.; Diaz-Castellon, R.; Rodriguez, J. L.

2007-12-01

Cofre de Perote volcano anchors the northern end of the easternmost of several volcanic chains orthogonal to the E-W trend of the Mexican Volcanic Belt (MVB). Its structure, geochemistry, and volcanic history diverge significantly from that of the large dominantly andesitic stratovolcanoes that have been the major focus of research efforts in the MVB. Andesitic-trachyandesitic to dacitic-trachydacitic effusive activity has predominated at Cofre de Perote, forming a massive low-angle compound shield volcano that dwarfs the more typical smaller shield volcanoes of the central and western MVB. The 4282-m-high volcano overlooking Xalapa, the capital city of the State of Veracruz, has a diameter of about 30 km and rises more than 3000 m above the coastal plain to the east. Repeated edifice collapse has left massive horseshoe-shaped scarps that truncate the eastern side of the edifice. Five major evolutionary stages characterize the growth of this compound volcano: 1) emplacement of a multiple-vent dome complex forming the basal structure of Cofre de Perote around 1.9-1.3 Ma; 2) construction of the basal part of the compound shield volcano from at least two main upper-edifice vents at about 400 ka; 3) effusion of the summit dome-like lavas through multiple vents at ca. 240 ka; 4) eruption of a large number of geochemically diverse, alkaline and calc-alkaline Pleistocene-to-Holocene monogenetic cones (likely related to regional volcanism) through the flanks of the Cofre de Perote edifice; 5) late-stage, large-volume edifice collapse on at least two occasions (ca. 40 ka and ca. 10 ka), producing long-runout debris avalanches that traveled to the east. An undated tephra layer from Cofre de Perote overlies deposits likely of the youngest collapse. Cofre de Perote is one of several volcanoes in the roughly N-S-trending chain that has undergone major edifice collapse. As with Citlaltepetl (Pico de Orizaba) and Las Cumbres volcanoes, Cofre de Perote was constructed at the eastern margin of the Altiplano, with pronounced differential relief and sloping substrate promoting failures toward the Gulf of Mexico coastal plain.

Reconnaissance geology of the Al Mukhul Quadrangle, sheet 26/42 B, Kingdom of Saudi Arabia

USGS Publications Warehouse

Du Bray, E.A.

1984-01-01

Mineral potential in the quadrangle is low. At a very small prospect pit in the north-central part of the quadrangle, massive, milky quartz veins cutting weakly metamorphosed volcanogenic sedimentary rocks are stained blue and green by copper minerals. A previously reported mine site in the southern part of the quadrangle was not relocated.

The low-metallicity starburst NGC346: massive-star population and feedback

NASA Astrophysics Data System (ADS)

Oskinova, Lida

2017-08-01

The Small Magellanic Cloud (SMC) is ideal to study young, massive stars at low metallicity. The compact cluster NGC346 contains about half of all O-type stars in the entire SMC. The massive-star population of this cluster powers N66, the brightest and largest HII region in the SMC. We propose to use HST-STIS to slice NGC346 with 20 long-slit exposures, in order to obtain the UV spectra of most of the massive early-type stars of this cluster. Archival data of 13 exposures that cover already a minor part of this cluster will be included in our analyses. Our aim is to quantitatively analyze virtually the whole massive-star population of NGC346. We have already secured the optical spectra of all massive stars in the field with the integral-field spectrograph MUSE at the ESO-VLT. However, for the determination of the stellar-wind parameters, i.e. the mass-loss rates and the wind velocities, ultraviolet spectra are indispensable. Our advanced Potsdam Wolf-Rayet (PoWR) code will be used for modeling the stellar and wind spectra in the course of the analysis. Finally, we will obtain:(a) the fundamental stellar and wind parameters of all stars brighter than spectral type B2V in the field, which, e,g,, will constrain the initial mass function in this young low-metallicity starburst;(b) mass-loss rates of many more OB-type stars at SMC metallicity than hitherto known, allowing to better constrain their metallicity dependence;(c) the integrated feedback by ionizing radiation and stellar winds of the whole massive-star population of NGC346, which will be used as input to model the ecology of the giant HII region N66.These HST UV data will be of high legacy value.

Simplified Antenna Group Determination of RS Overhead Reduced Massive MIMO for Wireless Sensor Networks.

PubMed

Lee, Byung Moo

2017-12-29

Massive multiple-input multiple-output (MIMO) systems can be applied to support numerous internet of things (IoT) devices using its excessive amount of transmitter (TX) antennas. However, one of the big obstacles for the realization of the massive MIMO system is the overhead of reference signal (RS), because the number of RS is proportional to the number of TX antennas and/or related user equipments (UEs). It has been already reported that antenna group-based RS overhead reduction can be very effective to the efficient operation of massive MIMO, but the method of deciding the number of antennas needed in each group is at question. In this paper, we propose a simplified determination scheme of the number of antennas needed in each group for RS overhead reduced massive MIMO to support many IoT devices. Supporting many distributed IoT devices is a framework to configure wireless sensor networks. Our contribution can be divided into two parts. First, we derive simple closed-form approximations of the achievable spectral efficiency (SE) by using zero-forcing (ZF) and matched filtering (MF) precoding for the RS overhead reduced massive MIMO systems with channel estimation error. The closed-form approximations include a channel error factor that can be adjusted according to the method of the channel estimation. Second, based on the closed-form approximation, we present an efficient algorithm determining the number of antennas needed in each group for the group-based RS overhead reduction scheme. The algorithm depends on the exact inverse functions of the derived closed-form approximations of SE. It is verified with theoretical analysis and simulation that the proposed algorithm works well, and thus can be used as an important tool for massive MIMO systems to support many distributed IoT devices.

Simplified Antenna Group Determination of RS Overhead Reduced Massive MIMO for Wireless Sensor Networks

PubMed Central

2017-01-01

Massive multiple-input multiple-output (MIMO) systems can be applied to support numerous internet of things (IoT) devices using its excessive amount of transmitter (TX) antennas. However, one of the big obstacles for the realization of the massive MIMO system is the overhead of reference signal (RS), because the number of RS is proportional to the number of TX antennas and/or related user equipments (UEs). It has been already reported that antenna group-based RS overhead reduction can be very effective to the efficient operation of massive MIMO, but the method of deciding the number of antennas needed in each group is at question. In this paper, we propose a simplified determination scheme of the number of antennas needed in each group for RS overhead reduced massive MIMO to support many IoT devices. Supporting many distributed IoT devices is a framework to configure wireless sensor networks. Our contribution can be divided into two parts. First, we derive simple closed-form approximations of the achievable spectral efficiency (SE) by using zero-forcing (ZF) and matched filtering (MF) precoding for the RS overhead reduced massive MIMO systems with channel estimation error. The closed-form approximations include a channel error factor that can be adjusted according to the method of the channel estimation. Second, based on the closed-form approximation, we present an efficient algorithm determining the number of antennas needed in each group for the group-based RS overhead reduction scheme. The algorithm depends on the exact inverse functions of the derived closed-form approximations of SE. It is verified with theoretical analysis and simulation that the proposed algorithm works well, and thus can be used as an important tool for massive MIMO systems to support many distributed IoT devices. PMID:29286339

A Combined Water-Bromotrifluoromethane Crash-Fire Protection System for a T-56 Turbopropeller Engine

NASA Technical Reports Server (NTRS)

Campbell, John A.; Busch, Arthur M.

1959-01-01

A crash-fire protection system is described which will suppress the ignition of crash-spilled fuel that may be ingested by a T-56 turbo-propeller engine. This system includes means for rapidly extinguishing the combustor flame, means for cooling and inerting with water the hot engine parts likely to ignite engine ingested fuel, and means for blanketing with bromotrifluoromethane massive metal parts that may reheat after the engine stops rotating. Combustion-chamber flames were rapidly extinguished at the engine fuel nozzles by a fuel shutoff and drain valve. Hot engine parts were inerted and cooled by 42 pounds of water discharged at seven engine stations. Massive metal parts that could reheat were inerted with 10 pounds of bromotrifluoromethane discharged at two engine stations. Performance trials of the crash-fire protection system were conducted by bringing the engine up to takeoff temperature, actuating the crash-fire protection system, and then spraying fuel into the engine to simulate crash-ingested fuel. No fires occurred during these trials, although fuel was sprayed into the engine from 0.3 second to 15 minutes after actuating the crash-fire protection system.

Massive integration of diverse protein quality assessment methods to improve template based modeling in CASP11.

PubMed

Cao, Renzhi; Bhattacharya, Debswapna; Adhikari, Badri; Li, Jilong; Cheng, Jianlin

2016-09-01

Model evaluation and selection is an important step and a big challenge in template-based protein structure prediction. Individual model quality assessment methods designed for recognizing some specific properties of protein structures often fail to consistently select good models from a model pool because of their limitations. Therefore, combining multiple complimentary quality assessment methods is useful for improving model ranking and consequently tertiary structure prediction. Here, we report the performance and analysis of our human tertiary structure predictor (MULTICOM) based on the massive integration of 14 diverse complementary quality assessment methods that was successfully benchmarked in the 11th Critical Assessment of Techniques of Protein Structure prediction (CASP11). The predictions of MULTICOM for 39 template-based domains were rigorously assessed by six scoring metrics covering global topology of Cα trace, local all-atom fitness, side chain quality, and physical reasonableness of the model. The results show that the massive integration of complementary, diverse single-model and multi-model quality assessment methods can effectively leverage the strength of single-model methods in distinguishing quality variation among similar good models and the advantage of multi-model quality assessment methods of identifying reasonable average-quality models. The overall excellent performance of the MULTICOM predictor demonstrates that integrating a large number of model quality assessment methods in conjunction with model clustering is a useful approach to improve the accuracy, diversity, and consequently robustness of template-based protein structure prediction. Proteins 2016; 84(Suppl 1):247-259. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Impact of Cosmological Satellites on Stellar Discs: Dissecting One Satellite at a Time

NASA Astrophysics Data System (ADS)

Hu, Shaoran; Sijacki, Debora

2018-05-01

Within the standard hierarchical structure formation scenario, Milky Way-mass dark matter haloes have hundreds of dark matter subhaloes with mass ≳ 108 M⊙. Over the lifetime of a galactic disc a fraction of these may pass close to the central region and interact with the disc. We extract the properties of subhaloes, such as their mass and trajectories, from a realistic cosmological simulation to study their potential effect on stellar discs. We find that massive subhalo impacts can generate disc heating, rings, bars, warps, lopsidedness as wells as spiral structures in the disc. Specifically, strong counter-rotating single-armed spiral structures form each time a massive subhalo passes through the disc. Such single-armed spirals wind up relatively quickly (over 1 - 2 Gyrs) and are generally followed by co-rotating two-armed spiral structures that both develop and wind up more slowly. In our simulations self-gravity in the disc is not very strong and these spiral structures are found to be kinematic density waves. We demonstrate that there is a clear link between each spiral mode in the disc and a given subhalo that caused it, and by changing the mass of the subhalo we can modulate the strength of the spirals. Furthermore, we find that the majority of subhaloes interact with the disc impulsively, such that the strength of spirals generated by subhaloes is proportional to the total torque they exert. We conclude that only a handful of encounters with massive subhaloes is sufficient for re-generating and sustaining spiral structures in discs over their entire lifetime.

Query-Structure Based Web Page Indexing

DTIC Science & Technology

2012-11-01

the massive amount of data present on the web. In our third participation in the web track at TREC 2012, we explore the idea of building an...the ad-hoc and diversity task. 1 INTRODUCTION The rapid growth and massive quantities of data on the Internet have increased the importance and...complexity of information retrieval systems. The amount and the diversity of the web data introduce shortcomings in the way search engines rank their

Cosmological perturbation and matter power spectrum in bimetric massive gravity

NASA Astrophysics Data System (ADS)

Geng, Chao-Qiang; Lee, Chung-Chi; Zhang, Kaituo

2018-04-01

We discuss the linear perturbation equations with the synchronous gauge in a minimal scenario of the bimetric massive gravity theory. We find that the matter density perturbation and matter power spectrum are suppressed. We also examine the ghost and stability problems and show that the allowed deviation of this gravitational theory from the cosmological constant is constrained to be smaller than O(10-2) by the large scale structure observational data.

Graviton 1-loop partition function for 3-dimensional massive gravity

NASA Astrophysics Data System (ADS)

Gaberdiel, Matthias R.; Grumiller, Daniel; Vassilevich, Dmitri

2010-11-01

Thegraviton1-loop partition function in Euclidean topologically massivegravity (TMG) is calculated using heat kernel techniques. The partition function does not factorize holomorphically, and at the chiral point it has the structure expected from a logarithmic conformal field theory. This gives strong evidence for the proposal that the dual conformal field theory to TMG at the chiral point is indeed logarithmic. We also generalize our results to new massive gravity.

Dynamic Imbalance Would Counter Offcenter Thrust

NASA Technical Reports Server (NTRS)

Mccanna, Jason

1994-01-01

Dynamic imbalance generated by offcenter thrust on rotating body eliminated by shifting some of mass of body to generate opposing dynamic imbalance. Technique proposed originally for spacecraft including massive crew module connected via long, lightweight intermediate structure to massive engine module, such that artificial gravitation in crew module generated by rotating spacecraft around axis parallel to thrust generated by engine. Also applicable to dynamic balancing of rotating terrestrial equipment to which offcenter forces applied.

Supporting communities in reducing their vulnerability against impacts of short-term heavy precipitation events

NASA Astrophysics Data System (ADS)

Hoy, Andreas; Hübener, Heike

2017-04-01

Potential flood areas are known and charted for most large and many small rivers in Europe. However, often no appropriate knowledge exists about the impacts of short-term intense precipitation (of mostly convective origin, occurring predominantly during the warm season) on small tributaries or on areas aside from waterways. Communities are often not sensitised and prepared for the massive surface runoff and subsequent flooding following massive downpours. Risks are particularly large in valley locations, where the water is canalised and immense flash floods may occur. Yet, each event has a different impact. Crucial factors determining these impacts are soil type, pre-event soil moisture, surface sealing, vegetation structure, slope gradients and many others. This contribution presents a framework to empower local communities - located within the central-German county of Hesse - to reduce their vulnerability against short-term intense precipitation events. The project consists of a data analysis part, in which information on observed heavy precipitation, (water related) disaster management actions of the local fire brigades, erosion risk maps, and further aspects are mapped to an integrated county-wide "heavy precipitation reference map" (german: "Starkregenhinweiskarte"). Another part of the project deals with the usability issue of heavy precipitation data in hydrological engineering. The goal of this part is to improve the use of the best available data and methods to assess - in very high resolution - areas at risk of flooding in case of such an event. This project part will culminate in exemplary "heavy precipitation hazard risk maps" (german: "Starkregengefahrenkarte") for two local communities in Hesse. In this presentation we will focus on ways how to communicate highly complex subject-specific scientific results of different sources to public decision makers in mostly small to medium-sized communities. Concrete challenges are to efficiently a) increase the awareness of the existing vulnerability to heavy precipitation events within the municipalities, b) convey the benefits of precaution measures, c) point out existing local deficiencies in disaster control and precaution measures and d) demonstrate opportunities to resolve them.

Tutorial: Asteroseismic Stellar Modelling with AIMS

NASA Astrophysics Data System (ADS)

Lund, Mikkel N.; Reese, Daniel R.

The goal of aims (Asteroseismic Inference on a Massive Scale) is to estimate stellar parameters and credible intervals/error bars in a Bayesian manner from a set of asteroseismic frequency data and so-called classical constraints. To achieve reliable parameter estimates and computational efficiency, it searches through a grid of pre-computed models using an MCMC algorithm—interpolation within the grid of models is performed by first tessellating the grid using a Delaunay triangulation and then doing a linear barycentric interpolation on matching simplexes. Inputs for the modelling consist of individual frequencies from peak-bagging, which can be complemented with classical spectroscopic constraints. aims is mostly written in Python with a modular structure to facilitate contributions from the community. Only a few computationally intensive parts have been rewritten in Fortran in order to speed up calculations.

Software solutions manage the definition, operation, maintenance and configuration control of the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dobson, D; Churby, A; Krieger, E

2011-07-25

The National Ignition Facility (NIF) is the world's largest laser composed of millions of individual parts brought together to form one massive assembly. Maintaining control of the physical definition, status and configuration of this structure is a monumental undertaking yet critical to the validity of the shot experiment data and the safe operation of the facility. The NIF business application suite of software provides the means to effectively manage the definition, build, operation, maintenance and configuration control of all components of the National Ignition Facility. State of the art Computer Aided Design software applications are used to generate a virtualmore » model and assemblies. Engineering bills of material are controlled through the Enterprise Configuration Management System. This data structure is passed to the Enterprise Resource Planning system to create a manufacturing bill of material. Specific parts are serialized then tracked along their entire lifecycle providing visibility to the location and status of optical, target and diagnostic components that are key to assessing pre-shot machine readiness. Nearly forty thousand items requiring preventive, reactive and calibration maintenance are tracked through the System Maintenance & Reliability Tracking application to ensure proper operation. Radiological tracking applications ensure proper stewardship of radiological and hazardous materials and help provide a safe working environment for NIF personnel.« less

NASA MISR Tracks Massive Flooding in Pakistan

NASA Image and Video Library

2010-08-18

In late July 2010, flooding caused by heavy monsoon rains began in several regions of Pakistan, including the Khyber Pakhtunkhwa, Sindh, Punjab and parts of Baluchistan. This image was acquired by NASA Terra spacecraft on August 11, 2010.

Assessment of Radiative Heating Uncertainty for Hyperbolic Earth Entry

NASA Technical Reports Server (NTRS)

Johnston, Christopher O.; Mazaheri, Alireza; Gnoffo, Peter A.; Kleb, W. L.; Sutton, Kenneth; Prabhu, Dinesh K.; Brandis, Aaron M.; Bose, Deepak

2011-01-01

This paper investigates the shock-layer radiative heating uncertainty for hyperbolic Earth entry, with the main focus being a Mars return. In Part I of this work, a baseline simulation approach involving the LAURA Navier-Stokes code with coupled ablation and radiation is presented, with the HARA radiation code being used for the radiation predictions. Flight cases representative of peak-heating Mars or asteroid return are de ned and the strong influence of coupled ablation and radiation on their aerothermodynamic environments are shown. Structural uncertainties inherent in the baseline simulations are identified, with turbulence modeling, precursor absorption, grid convergence, and radiation transport uncertainties combining for a +34% and ..24% structural uncertainty on the radiative heating. A parametric uncertainty analysis, which assumes interval uncertainties, is presented. This analysis accounts for uncertainties in the radiation models as well as heat of formation uncertainties in the flow field model. Discussions and references are provided to support the uncertainty range chosen for each parameter. A parametric uncertainty of +47.3% and -28.3% is computed for the stagnation-point radiative heating for the 15 km/s Mars-return case. A breakdown of the largest individual uncertainty contributors is presented, which includes C3 Swings cross-section, photoionization edge shift, and Opacity Project atomic lines. Combining the structural and parametric uncertainty components results in a total uncertainty of +81.3% and ..52.3% for the Mars-return case. In Part II, the computational technique and uncertainty analysis presented in Part I are applied to 1960s era shock-tube and constricted-arc experimental cases. It is shown that experiments contain shock layer temperatures and radiative ux values relevant to the Mars-return cases of present interest. Comparisons between the predictions and measurements, accounting for the uncertainty in both, are made for a range of experiments. A measure of comparison quality is de ned, which consists of the percent overlap of the predicted uncertainty bar with the corresponding measurement uncertainty bar. For nearly all cases, this percent overlap is greater than zero, and for most of the higher temperature cases (T >13,000 K) it is greater than 50%. These favorable comparisons provide evidence that the baseline computational technique and uncertainty analysis presented in Part I are adequate for Mars-return simulations. In Part III, the computational technique and uncertainty analysis presented in Part I are applied to EAST shock-tube cases. These experimental cases contain wavelength dependent intensity measurements in a wavelength range that covers 60% of the radiative intensity for the 11 km/s, 5 m radius flight case studied in Part I. Comparisons between the predictions and EAST measurements are made for a range of experiments. The uncertainty analysis presented in Part I is applied to each prediction, and comparisons are made using the metrics defined in Part II. The agreement between predictions and measurements is excellent for velocities greater than 10.5 km/s. Both the wavelength dependent and wavelength integrated intensities agree within 30% for nearly all cases considered. This agreement provides confidence in the computational technique and uncertainty analysis presented in Part I, and provides further evidence that this approach is adequate for Mars-return simulations. Part IV of this paper reviews existing experimental data that include the influence of massive ablation on radiative heating. It is concluded that this existing data is not sufficient for the present uncertainty analysis. Experiments to capture the influence of massive ablation on radiation are suggested as future work, along with further studies of the radiative precursor and improvements in the radiation properties of ablation products.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vieira, H.S., E-mail: horacio.santana.vieira@hotmail.com; Centro de Ciências, Tecnologia e Saúde, Universidade Estadual da Paraíba, CEP 58233-000, Araruna, PB; Bezerra, V.B., E-mail: valdir@fisica.ufpb.br

Charged massive scalar fields are considered in the gravitational and electromagnetic field produced by a dyonic black hole with a cosmic string along its axis of symmetry. Exact solutions of both angular and radial parts of the covariant Klein–Gordon equation in this background are obtained, and are given in terms of the confluent Heun functions. The role of the presence of the cosmic string in these solutions is showed up. From the radial solution, we obtain the exact wave solutions near the exterior horizon of the black hole, and discuss the Hawking radiation spectrum and the energy flux. -- Highlights:more » •A cosmic string is introduced along the axis of symmetry of the dyonic black hole. •The covariant Klein–Gordon equation for a charged massive scalar field in this background is analyzed. •Both angular and radial parts are transformed to a confluent Heun equation. •The resulting Hawking radiation spectrum and the energy flux are obtained.« less

Zinc isotopes in sphalerite from base metal deposits in the Red Dog district, northern Alaska

USGS Publications Warehouse

Kelley, K.D.; Wilkinson, J.J.; Chapman, J.B.; Crowther, H.L.; Weiss, D.J.

2009-01-01

Analyses of sphalerite samples from shale-hosted massive sulfide and stratigraphically underlying vein breccia deposits in the Red Dog district in northern Alaska show a range ??66Zn values from zero to 0.60 per mil. The lowest values are observed in the vein breccia deposits, and the stratigraphically overlying (but structurally displaced) shale-hosted massive sulfide deposits show a systematic trend of increasing ??66Zn values from south to north (Main-Aqqaluk-Paalaaq-Anarraaq). The ??66Zn values are inversely correlated with sphalerite Fe/Mn ratio and also tend to be higher in low Cu sphalerite, consistent with precipitation of lower ??66Zn sphalerite closer to the principal hydrothermal fluid conduits. The most likely control on isotopic variation is Rayleigh fractionation during sulfide precipitation, with lighter zinc isotopes preferentially incorporated in the earliest sphalerite to precipitate from ore fluids at deeper levels (vein breccias) and close to the principal fluid conduits in the orebodies, followed by precipitation of sulfides with higher ??66Zn values in shallower and/or more distal parts of the flow path. There is no systematic variation among the paragenetic stages of sphalerite from a single deposit, suggesting an isotopically homogeneous zinc source and consistent transport-deposition conditions and/or dissolution-reprecipitation of earlier sphalerite without significant fractionation. Decoupled Zn and S isotope compositions are best explained by mixing of separate metal- and sulfur-bearing fluids at the depositional site. The results confirm that Zn isotopes may be a useful tracer for distinguishing between the central and distal parts of large hydrothermal systems as previously suggested and could therefore be of use in exploration. ?? 2009 by Economic Geology.

Protostar formation in the early universe.

PubMed

Yoshida, Naoki; Omukai, Kazuyuki; Hernquist, Lars

2008-08-01

The nature of the first generation of stars in the universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability. We have developed an ab initio computer simulation of the formation of primordial stars that follows the relevant atomic and molecular processes in a primordial gas in an expanding universe. The results show that primeval density fluctuations left over from the Big Bang can drive the formation of a tiny protostar with a mass 1% that of the Sun. The protostar is a seed for the subsequent formation of a massive primordial star.

Resurrecting hot dark matter - Large-scale structure from cosmic strings and massive neutrinos

NASA Technical Reports Server (NTRS)

Scherrer, Robert J.

1988-01-01

These are the results of a numerical simulation of the formation of large-scale structure from cosmic-string loops in a universe dominated by massive neutrinos (hot dark matter). This model has several desirable features. The final matter distribution contains isolated density peaks embedded in a smooth background, producing a natural bias in the distribution of luminous matter. Because baryons can accrete onto the cosmic strings before the neutrinos, the galaxies will have baryon cores and dark neutrino halos. Galaxy formation in this model begins much earlier than in random-phase models. On large scales the distribution of clustered matter visually resembles the CfA survey, with large voids and filaments.

Steady and unsteady three-dimensional transonic flow computations by integral equation method

NASA Technical Reports Server (NTRS)

Hu, Hong

1994-01-01

This is the final technical report of the research performed under the grant: NAG1-1170, from the National Aeronautics and Space Administration. The report consists of three parts. The first part presents the work on unsteady flows around a zero-thickness wing. The second part presents the work on steady flows around non-zero thickness wings. The third part presents the massively parallel processing implementation and performance analysis of integral equation computations. At the end of the report, publications resulting from this grant are listed and attached.

Gravitational Instabilities in the Disks of Massive Protostars as an Explanation for Linear Distributions of Methanol Masers

NASA Astrophysics Data System (ADS)

Durisen, Richard H.; Mejia, Annie C.; Pickett, Brian K.; Hartquist, Thomas W.

2001-12-01

Evidence suggests that some masers associated with massive protostars may originate in the outer regions of large disks, at radii of hundreds to thousands of AU from the central mass. This is particularly true for methanol (CH3OH), for which linear distributions of masers are found with disklike kinematics. In three-dimensional hydrodynamics simulations we have made to study the effects of gravitational instabilities in the outer parts of disks around young low-mass stars, the nonlinear development of the instabilities leads to a complex of intersecting spiral shocks, clumps, and arclets within the disk and to significant time-dependent, nonaxisymmetric distortions of the disk surface. A rescaling of our disk simulations to the case of a massive protostar shows that conditions in the disturbed outer disk seem conducive to the appearance of masers if it is viewed edge-on.

Using CLIPS in the domain of knowledge-based massively parallel programming

NASA Technical Reports Server (NTRS)

Dvorak, Jiri J.

1994-01-01

The Program Development Environment (PDE) is a tool for massively parallel programming of distributed-memory architectures. Adopting a knowledge-based approach, the PDE eliminates the complexity introduced by parallel hardware with distributed memory and offers complete transparency in respect of parallelism exploitation. The knowledge-based part of the PDE is realized in CLIPS. Its principal task is to find an efficient parallel realization of the application specified by the user in a comfortable, abstract, domain-oriented formalism. A large collection of fine-grain parallel algorithmic skeletons, represented as COOL objects in a tree hierarchy, contains the algorithmic knowledge. A hybrid knowledge base with rule modules and procedural parts, encoding expertise about application domain, parallel programming, software engineering, and parallel hardware, enables a high degree of automation in the software development process. In this paper, important aspects of the implementation of the PDE using CLIPS and COOL are shown, including the embedding of CLIPS with C++-based parts of the PDE. The appropriateness of the chosen approach and of the CLIPS language for knowledge-based software engineering are discussed.

Massively Parallel Solution of Poisson Equation on Coarse Grain MIMD Architectures

NASA Technical Reports Server (NTRS)

Fijany, A.; Weinberger, D.; Roosta, R.; Gulati, S.

1998-01-01

In this paper a new algorithm, designated as Fast Invariant Imbedding algorithm, for solution of Poisson equation on vector and massively parallel MIMD architectures is presented. This algorithm achieves the same optimal computational efficiency as other Fast Poisson solvers while offering a much better structure for vector and parallel implementation. Our implementation on the Intel Delta and Paragon shows that a speedup of over two orders of magnitude can be achieved even for moderate size problems.

The Galactic Distribution of Massive Star Formation from the Red MSX Source Survey

NASA Astrophysics Data System (ADS)

Figura, Charles C.; Urquhart, J. S.

2013-01-01

Massive stars inject enormous amounts of energy into their environments in the form of UV radiation and molecular outflows, creating HII regions and enriching local chemistry. These effects provide feedback mechanisms that aid in regulating star formation in the region, and may trigger the formation of subsequent generations of stars. Understanding the mechanics of massive star formation presents an important key to understanding this process and its role in shaping the dynamics of galactic structure. The Red MSX Source (RMS) survey is a multi-wavelength investigation of ~1200 massive young stellar objects (MYSO) and ultra-compact HII (UCHII) regions identified from a sample of colour-selected sources from the Midcourse Space Experiment (MSX) point source catalog and Two Micron All Sky Survey. We present a study of over 900 MYSO and UCHII regions investigated by the RMS survey. We review the methods used to determine distances, and investigate the radial galactocentric distribution of these sources in context with the observed structure of the galaxy. The distribution of MYSO and UCHII regions is found to be spatially correlated with the spiral arms and galactic bar. We examine the radial distribution of MYSOs and UCHII regions and find variations in the star formation rate between the inner and outer Galaxy and discuss the implications for star formation throughout the galactic disc.

[NEII] Line Velocity Structure of Ultracompact HII Regions

NASA Astrophysics Data System (ADS)

Okamoto, Yoshiko K.; Kataza, Hirokazu; Yamashita, Takuya; Miyata, Takashi; Sako, Shigeyuki; Honda, Mitsuhiko; Onaka, Takashi; Fujiyoshi, Takuya

Newly formed massive stars are embedded in their natal molecular clouds and are observed as ultracompact HII regions. They emit strong ionic lines such as [NeII] 12.8 micron. Since Ne is ionized by UV photons of E>21.6eV which is higher than the ionization energy of hydrogen atoms the line probes the ionized gas near the ionizing stars. This enables to probe gas motion in the vicinity of recently-formed massive stars. High angular and spectral resolution observations of the [NeII] line will thus provide siginificant information on structures (e.g. disks and outflows) generated through massive star formation. We made [NeII] spectroscopy of ultracompact HII regions using the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on the 8.2m Subaru Telescope in July 2002. Spatial and spectral resolutions were 0.5"" and 10000 respectively. Among the targets G45.12+0.13 shows the largest spatial variation in velocity. The brightest area of G45.12+0.13 has the largest line width in the object. The total velocity deviation amounts to 50km/s (peak to peak value) in the observed area. We report the velocity structure of [NeII] emission of G45.12+0.13 and discuss the gas motion near the ionizing star.

A Generic Mesh Data Structure with Parallel Applications

ERIC Educational Resources Information Center

Cochran, William Kenneth, Jr.

2009-01-01

High performance, massively-parallel multi-physics simulations are built on efficient mesh data structures. Most data structures are designed from the bottom up, focusing on the implementation of linear algebra routines. In this thesis, we explore a top-down approach to design, evaluating the various needs of many aspects of simulation, not just…

Massive star formation by accretion. II. Rotation: how to circumvent the angular momentum barrier?

NASA Astrophysics Data System (ADS)

Haemmerlé, L.; Eggenberger, P.; Meynet, G.; Maeder, A.; Charbonnel, C.; Klessen, R. S.

2017-06-01

Context. Rotation plays a key role in the star-formation process, from pre-stellar cores to pre-main-sequence (PMS) objects. Understanding the formation of massive stars requires taking into account the accretion of angular momentum during their PMS phase. Aims: We study the PMS evolution of objects destined to become massive stars by accretion, focusing on the links between the physical conditions of the environment and the rotational properties of young stars. In particular, we look at the physical conditions that allow the production of massive stars by accretion. Methods: We present PMS models computed with a new version of the Geneva Stellar Evolution code self-consistently including accretion and rotation according to various accretion scenarios for mass and angular momentum. We describe the internal distribution of angular momentum in PMS stars accreting at high rates and we show how the various physical conditions impact their internal structures, evolutionary tracks, and rotation velocities during the PMS and the early main sequence. Results: We find that the smooth angular momentum accretion considered in previous studies leads to an angular momentum barrier and does not allow the formation of massive stars by accretion. A braking mechanism is needed in order to circumvent this angular momentum barrier. This mechanism has to be efficient enough to remove more than two thirds of the angular momentum from the inner accretion disc. Due to the weak efficiency of angular momentum transport by shear instability and meridional circulation during the accretion phase, the internal rotation profiles of accreting stars reflect essentially the angular momentum accretion history. As a consequence, careful choice of the angular momentum accretion history allows circumvention of any limitation in mass and velocity, and production of stars of any mass and velocity compatible with structure equations.

Phenomenology in minimal theory of massive gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Felice, Antonio De; Mukohyama, Shinji; Kavli Institute for the Physics and Mathematics of the Universe

2016-04-15

We investigate the minimal theory of massive gravity (MTMG) recently introduced. After reviewing the original construction based on its Hamiltonian in the vielbein formalism, we reformulate it in terms of its Lagrangian in both the vielbein and the metric formalisms. It then becomes obvious that, unlike previous attempts in the literature of Lorentz-violating massive gravity, not only the potential but also the kinetic structure of the action is modified from the de Rham-Gabadadze-Tolley (dRGT) massive gravity theory. We confirm that the number of physical degrees of freedom in MTMG is two at fully nonlinear level. This proves the absence ofmore » various possible pathologies such as superluminality, acausality and strong coupling. Afterwards, we discuss the phenomenology of MTMG in the presence of a dust fluid. We find that on a flat homogeneous and isotropic background we have two branches. One of them (self-accelerating branch) naturally leads to acceleration without the genuine cosmological constant or dark energy. For this branch both the scalar and the vector modes behave exactly as in general relativity (GR). The phenomenology of this branch differs from GR in the tensor modes sector, as the tensor modes acquire a non-zero mass. Hence, MTMG serves as a stable nonlinear completion of the self-accelerating cosmological solution found originally in dRGT theory. The other branch (normal branch) has a dynamics which depends on the time-dependent fiducial metric. For the normal branch, the scalar mode sector, even though as in GR only one scalar mode is present (due to the dust fluid), differs from the one in GR, and, in general, structure formation will follow a different phenomenology. The tensor modes will be massive, whereas the vector modes, for both branches, will have the same phenomenology as in GR.« less

THE STRUCTURE OF THE MERGING RCS 231953+00 SUPERCLUSTER AT z {approx} 0.9

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faloon, A. J.; Webb, T. M. A.; Geach, J. E.

2013-05-10

The RCS 2319+00 supercluster is a massive supercluster at z = 0.9 comprising three optically selected, spectroscopically confirmed clusters separated by <3 Mpc on the plane of the sky. This supercluster is one of a few known examples of the progenitors of present-day massive clusters (10{sup 15} M{sub Sun} by z {approx} 0.5). We present an extensive spectroscopic campaign carried out on the supercluster field resulting, in conjunction with previously published data, in 1961 high-confidence galaxy redshifts. We find 302 structure members spanning three distinct redshift walls separated from one another by {approx}65 Mpc ({Delta} z = 0.03). The componentmore » clusters have spectroscopic redshifts of 0.901, 0.905, and 0.905. The velocity dispersions are consistent with those predicted from X-ray data, giving estimated cluster masses of {approx}10{sup 14.5}-10{sup 14.9} M{sub Sun }. The Dressler-Shectman test finds evidence of substructure in the supercluster field and a friends-of-friends analysis identified five groups in the supercluster, including a filamentary structure stretching between two cluster cores previously identified in the infrared by Coppin et al. The galaxy colors further show this filamentary structure to be a unique region of activity within the supercluster, comprised mainly of blue galaxies compared to the {approx}43%-77% red-sequence galaxies present in the other groups and cluster cores. Richness estimates from stacked luminosity function fits result in average group mass estimates consistent with {approx}10{sup 13} M{sub Sun} halos. Currently, 22% of our confirmed members reside in {approx}> 10{sup 13} M{sub Sun} groups/clusters destined to merge onto the most massive cluster, in agreement with the massive halo galaxy fractions important in cluster galaxy pre-processing in N-body simulation merger tree studies.« less

Galaxy growth in a massive halo in the first billion years of cosmic history

NASA Astrophysics Data System (ADS)

Marrone, D. P.; Spilker, J. S.; Hayward, C. C.; Vieira, J. D.; Aravena, M.; Ashby, M. L. N.; Bayliss, M. B.; Béthermin, M.; Brodwin, M.; Bothwell, M. S.; Carlstrom, J. E.; Chapman, S. C.; Chen, Chian-Chou; Crawford, T. M.; Cunningham, D. J. M.; De Breuck, C.; Fassnacht, C. D.; Gonzalez, A. H.; Greve, T. R.; Hezaveh, Y. D.; Lacaille, K.; Litke, K. C.; Lower, S.; Ma, J.; Malkan, M.; Miller, T. B.; Morningstar, W. R.; Murphy, E. J.; Narayanan, D.; Phadke, K. A.; Rotermund, K. M.; Sreevani, J.; Stalder, B.; Stark, A. A.; Strandet, M. L.; Tang, M.; Weiß, A.

2018-01-01

According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field. Observing these structures during their period of active growth and assembly—the first few hundred million years of the Universe—is challenging because it requires surveys that are sensitive enough to detect the distant galaxies that act as signposts for these structures and wide enough to capture the rarest objects. As a result, very few such objects have been detected so far. Here we report observations of a far-infrared-luminous object at redshift 6.900 (less than 800 million years after the Big Bang) that was discovered in a wide-field survey. High-resolution imaging shows it to be a pair of extremely massive star-forming galaxies. The larger is forming stars at a rate of 2,900 solar masses per year, contains 270 billion solar masses of gas and 2.5 billion solar masses of dust, and is more massive than any other known object at a redshift of more than 6. Its rapid star formation is probably triggered by its companion galaxy at a projected separation of 8 kiloparsecs. This merging companion hosts 35 billion solar masses of stars and has a star-formation rate of 540 solar masses per year, but has an order of magnitude less gas and dust than its neighbour and physical conditions akin to those observed in lower-metallicity galaxies in the nearby Universe. These objects suggest the presence of a dark-matter halo with a mass of more than 100 billion solar masses, making it among the rarest dark-matter haloes that should exist in the Universe at this epoch.

Galaxy growth in a massive halo in the first billion years of cosmic history.

PubMed

Marrone, D P; Spilker, J S; Hayward, C C; Vieira, J D; Aravena, M; Ashby, M L N; Bayliss, M B; Béthermin, M; Brodwin, M; Bothwell, M S; Carlstrom, J E; Chapman, S C; Chen, Chian-Chou; Crawford, T M; Cunningham, D J M; De Breuck, C; Fassnacht, C D; Gonzalez, A H; Greve, T R; Hezaveh, Y D; Lacaille, K; Litke, K C; Lower, S; Ma, J; Malkan, M; Miller, T B; Morningstar, W R; Murphy, E J; Narayanan, D; Phadke, K A; Rotermund, K M; Sreevani, J; Stalder, B; Stark, A A; Strandet, M L; Tang, M; Weiß, A

2018-01-04

According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field. Observing these structures during their period of active growth and assembly-the first few hundred million years of the Universe-is challenging because it requires surveys that are sensitive enough to detect the distant galaxies that act as signposts for these structures and wide enough to capture the rarest objects. As a result, very few such objects have been detected so far. Here we report observations of a far-infrared-luminous object at redshift 6.900 (less than 800 million years after the Big Bang) that was discovered in a wide-field survey. High-resolution imaging shows it to be a pair of extremely massive star-forming galaxies. The larger is forming stars at a rate of 2,900 solar masses per year, contains 270 billion solar masses of gas and 2.5 billion solar masses of dust, and is more massive than any other known object at a redshift of more than 6. Its rapid star formation is probably triggered by its companion galaxy at a projected separation of 8 kiloparsecs. This merging companion hosts 35 billion solar masses of stars and has a star-formation rate of 540 solar masses per year, but has an order of magnitude less gas and dust than its neighbour and physical conditions akin to those observed in lower-metallicity galaxies in the nearby Universe. These objects suggest the presence of a dark-matter halo with a mass of more than 100 billion solar masses, making it among the rarest dark-matter haloes that should exist in the Universe at this epoch.

Massive and Distant Clusters of WISE Survey (MaDCoWS)

NASA Astrophysics Data System (ADS)

Brodwin, Mark; MaDCoWS Collaboration

2018-06-01

The Massive and Distant Clusters of WISE Survey (MaDCoWS) is a comprehensive program to detect and characterize the most massive galaxy clusters in the Universe at z ~ 1, and is the only all-sky survey sensitive to galaxy clusters at this epoch. The foundation for this program is data from the NASA Wide-field Infrared Survey Explorer (WISE). The primary goal is to study the evolution of massive galaxies in the most overdense environments at z > 1 when star formation and AGN activity may be peaking in these structures. Spitzer follow-up imaging of 2000 MaDCoWS clusters has allowed us to select the richest and/or most distant clusters for detailed study. To date we have spectroscopically confirmed over 35 MaDCoWS clusters, spanning a wide range of masses (2-11 x 10^14 Msun), out to z = 1.5. This includes the discovery of the most massive z > 1.15 cluster found to date, as well as a cluster at z = 1.23 that is lensing a z = 2.22 supernova Ia. Multiwavelength follow-up observations of these distant clusters, currently underway, will permit several novel studies of galaxy evolution in rich cluster environments at z > 1.

Physical Conditions of Eta Car Complex Environment Revealed From Photoionization Modeling

NASA Technical Reports Server (NTRS)

Verner, E. M.; Bruhweiler, F.; Nielsen, K. E.; Gull, T.; Kober, G. Vieira; Corcoran, M.

2006-01-01

The very massive star, Eta Carinae, is enshrouded in an unusual complex environment of nebulosities and structures. The circumstellar gas gives rise to distinct absorption and emission components at different velocities and distances from the central source(s). Through photoionization modeling, we find that the radiation field from the more massive B-star companion supports the low ionization structure throughout the 5.54 year period. The radiation field of an evolved O-star is required to produce the higher ionization . emission seen across the broad maximum. Our studies utilize the HST/STIS data and model calculations of various regimes from doubly ionized species (T= 10,000K) to the low temperature (T = 760 K) conditions conductive to molecule formation (CH and OH). Overall analysis suggests the high depletion in C and O and the enrichment in He and N. The sharp molecular and ionic absorptions in this extensively CNO - processed material offers a unique environment for studying the chemistry, dust formation processes, and nucleosynthesis in the ejected layers of a highly evolved massive star.

Evolution and alteration in situ of a massive iron duricrust in Central Africa

NASA Astrophysics Data System (ADS)

Bitom, Dieudonné; Volkoff, Boris; Abossolo-Angue, Monique

2003-08-01

A soil sequence with iron duricrust is described in an area covered by tropical rain forest in South Cameroon. The dismantling of the iron duricrust is documented through a close observation of a soft duricrust, which corresponds to a transitional stage in the degradation of a massive iron duricrust into a loose nodular horizon. In the initial massive and hematitic duricrust, nodular shapes are progressively formed. The nodules and the internodular matrix remain hematitic. The internodular matrix undergoes goethitization and a pronounced deferruginisation before loosening; the primary structure of the iron duricrust is maintained, however, due to internodular bridges, relics of internodular matrix which escaped the process of goethitization. The iron is gradually released from these hematitic bridges, which become softer. This leads to the collapse of the initial structures of the iron duricrust and to the formation of a loose nodular material with a clayey matrix containing kaolinite and goethite. Many loose nodular horizons, which are found all over Central Africa, may have been formed by such alteration of a former iron duricrust.

Deconstructing the neutrino mass constraint from galaxy redshift surveys

NASA Astrophysics Data System (ADS)

Boyle, Aoife; Komatsu, Eiichiro

2018-03-01

The total mass of neutrinos can be constrained in a number of ways using galaxy redshift surveys. Massive neutrinos modify the expansion rate of the Universe, which can be measured using baryon acoustic oscillations (BAOs) or the Alcock-Paczynski (AP) test. Massive neutrinos also change the structure growth rate and the amplitude of the matter power spectrum, which can be measured using redshift-space distortions (RSD). We use the Fisher matrix formalism to disentangle these information sources, to provide projected neutrino mass constraints from each of these probes alone and to determine how sensitive each is to the assumed cosmological model. We isolate the distinctive effect of neutrino free-streaming on the matter power spectrum and structure growth rate as a signal unique to massive neutrinos that can provide the most robust constraints, which are relatively insensitive to extensions to the cosmological model beyond ΛCDM . We also provide forecasted constraints using all of the information contained in the observed galaxy power spectrum combined, and show that these maximally optimistic constraints are primarily limited by the accuracy to which the optical depth of the cosmic microwave background, τ, is known.

Preliminary results of spectral induced polarization measurements, Wadi Bidah District, Kingdom of Saudi Arabia

USGS Publications Warehouse

Smith, Bruce D.; Tippens, C.L.; Flanigan, V.J.; Sadek, Hamdy

1983-01-01

Laboratory spectral induced polarization (SIP) measurements on 29 carbonaceous schist samples from the Wadi Bidah district show that most are associated with very long polarization decays or, equivalently, large time constants. In contrast, measurements on two massive sulfide samples indicate shorter polarization decays or smaller time constants. This difference in time constants for the polarization process results in two differences in the phase spectra in the frequency range of from 0.06 to 1Hz. First, phase values of carbonaceous rocks generally decrease as a function of increasing frequency. Second, phase values of massive sulfide-bearing rocks increase as a function of increasing frequency. These results from laboratory measurements agree well with those from other reported SIP measurements on graphites and massive sulfides from the Canadian Shield. Four SIP lines, measured by using a 50-m dipole-dipole array, were surveyed at the Rabathan 4 prospect to test how well the results of laboratory sample measurements can be applied to larger scale field measurements. Along one line, located entirely over carbonaceous schists, the phase values decreased as a function of increasing frequency. Along a second line, located over both massive sulfides and carbonaceous schists as defined by drilling, the phase values measured over carbonaceous schists decreased as a function of increasing frequency, whereas those measured over massive sulfides increased. In addition, parts of two lines were surveyed down the axes of the massive sulfide and carbonaceous units. The phase values along these lines showed similar differences between the carbonaceous schists and massive sulfides. To date, the SIP survey and the SIP laboratory measurements have produced the only geophysical data that indicate an electrical difference between the massive sulfide-bearing rocks and the surrounding carbonaceous rocks in the Wadi Bidah district. However, additional sample and field measurements in areas of known mineralization would fully evaluate the SIP method as applied to various geologic environments and styles of massive sulfide mineralization. Additionally, the efficiency of SIP surveys in delineating areas of sulfide mineralization might be improved by surveying lines down the axes of known electrical conductors. An evaluation of the applied research done on the SIP method to date suggests that this technique offers significant exploration applications to massive sulfide exploration in the Kingdom of Saudi Arabia.

e-MERLIN and the COBRaS legacy Project

NASA Astrophysics Data System (ADS)

Peck, Luke

2011-07-01

As one of the 12 legacy programmes given ~300 hrs observing time on the newly enhanced e-MERLIN; the Cygnus OB2 Radio Survey (COBRaS) (homepage: http://www.homepages.ucl.ac.uk/~ucapdwi/cobras/) is an intensive deep-field mapping of the Cyg OB2 association in the Cygnus region of our Galaxy. This will provide the most detailed census for the most massive OB association in the northern hemisphere. A range of astrophysical problems and themes will be investigated including: mass loss and evolution of massive stars; the formation, dynamics and content of massive OB associations and the frequency of massive binaries and the incidence of non-thermal radiation. As part of of the initial ground work for this project, extensive meta-data catalogues were amalgamated from various catalogues from the Virtual Observatory database. In this talk I will discuss; investigations into JHK photometric techniques which can help identify possible OB candidates and other spectral classes; theoretical mass loss models as described by Vink et al. 2001 along with stellar parameters from Martins et al. 2005, Searle et al. 2008 and Prinja et al 1990 which pave the way to calculate theoretical mass loss rates for smooth winds of O stars and B supergiants, and the predicted 6cm fluxes resulting from the thermal free-free radiation in their winds. This will be essential for the study of clumped winds which is an early goal for this project. Over the months following from when this abstract was written; the first e-MERLIN pointings are expected. In the event of obtaining data, this will also be included in the presentation as part of the 'early science' from e-MERLIN and COBRaS.

Rupture dynamics along dipping thrust faults: free surface interaction and the case of Tohoku earthquake

NASA Astrophysics Data System (ADS)

Festa, Gaetano; Scala, Antonio; Vilotte, Jean-Pierre

2017-04-01

To address the influence of the free surface interaction on rupture propagating along subduction zones, we numerically investigate dynamic interactions, involving coupling between normal and shear tractions, between in-plane rupture propagating along dipping thrust faults and a free surface for different structural and geometrical conditions. When the rupture occurs along reverse fault with a dip angle different from 90° the symmetry is broken as an effect of slip-induced normal stress perturbations and a larger ground motion is evidenced on the hanging wall. The ground motion is amplified by multiple reflections of waves trapped between the fault and the free surface. This effect is shown to occur when the rupture tip lies on the vertical below the intersection between the S-wave front and the surface that is when waves along the surface start to interact with the rupture front. This interaction is associated with a finite region where the rupture advances in a massive regime preventing the shrinking of the process zone and the emission of high-frequency radiation. The smaller the dip angle the larger co-seismic slip in the shallow part as an effect of the significant break of symmetry. Radiation from shallow part is still depleted in high frequencies due to the massive propagating regime and the interaction length dominating the rupture dynamics. Instantaneous shear response to normal traction perturbations may lead to unstable solutions as in the case of bimaterial rupture. A parametric study has been performed to analyse the effects of a regularised shear traction response to normal traction variations. Finally the case of Tohoku earthquake is considered and we present 2D along-dip numerical results. At first order the larger slip close to the trench can be ascribed to the break of symmetry and the interaction with free surface. When shear/normal coupling is properly regularised the signal from the trench is depleted in high frequencies whereas during deep propagation high-frequency radiations emerge associated to geometrical and structural complexities or to frictional strength asperities.

Thought Leaders during Crises in Massive Social Networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corley, Courtney D.; Farber, Robert M.; Reynolds, William

The vast amount of social media data that can be gathered from the internet coupled with workflows that utilize both commodity systems and massively parallel supercomputers, such as the Cray XMT, open new vistas for research to support health, defense, and national security. Computer technology now enables the analysis of graph structures containing more than 4 billion vertices joined by 34 billion edges along with metrics and massively parallel algorithms that exhibit near-linear scalability according to number of processors. The challenge lies in making this massive data and analysis comprehensible to an analyst and end-users that require actionable knowledge tomore » carry out their duties. Simply stated, we have developed language and content agnostic techniques to reduce large graphs built from vast media corpora into forms people can understand. Specifically, our tools and metrics act as a survey tool to identify thought leaders' -- those members that lead or reflect the thoughts and opinions of an online community, independent of the source language.« less

Massive star evolution and SN 1987A

NASA Technical Reports Server (NTRS)

Arnett, David

1991-01-01

The evolution of massive stars through hydrogen and helium burning is addressed. A set of stellar evolutionary sequences for mass/solar mass of 15, 20, and 25, and metallicity of 0.002, 0.005, 0.007, 0.010, and 0.20 are presented; semiconvection is restricted to operating slower than the local thermal time scale. Using these sequences, simple models of the massive star content of the LMC are found to agree moderately well with the new observational data of Fitzpatrick and Garmany (1990). LMC supergiants were detected only in their postmain-sequence phases, so that 5-10 times more massive stars are there but not identified as such. It is argued that SN 1987A exhibits the normal evolution of a single star of about 20 solar mases having LMC abundances. Despite the variety of envelope behavior, the structure of the core at collapse is rather similar for the stars of a given mass. Variations due to different rates of mass loss are likely to be larger than those due to composition.

What drives the formation of massive stars and clusters?

NASA Astrophysics Data System (ADS)

Ochsendorf, Bram; Meixner, Margaret; Roman-Duval, Julia; Evans, Neal J., II; Rahman, Mubdi; Zinnecker, Hans; Nayak, Omnarayani; Bally, John; Jones, Olivia C.; Indebetouw, Remy

2018-01-01

Galaxy-wide surveys allow to study star formation in unprecedented ways. In this talk, I will discuss our analysis of the Large Magellanic Cloud (LMC) and the Milky Way, and illustrate how studying both the large and small scale structure of galaxies are critical in addressing the question: what drives the formation of massive stars and clusters?I will show that ‘turbulence-regulated’ star formation models do not reproduce massive star formation properties of GMCs in the LMC and Milky Way: this suggests that theory currently does not capture the full complexity of star formation on small scales. I will also report on the discovery of a massive star forming complex in the LMC, which in many ways manifests itself as an embedded twin of 30 Doradus: this may shed light on the formation of R136 and 'Super Star Clusters' in general. Finally, I will highlight what we can expect in the next years in the field of star formation with large-scale sky surveys, ALMA, and our JWST-GTO program.

The Magnetic Properties of Galactic OB Stars from the Magnetism in Massive Stars Project

NASA Astrophysics Data System (ADS)

Wade, Gregg A.; Grunhut, Jason; Petit, Veronique; Neiner, Coralie; Alecian, Evelyne; Landstreet, John; MiMeS Collaboration

2013-06-01

The Magnetism in Massive Stars (MiMeS) project represents the largest systematic survey of stellar magnetism ever undertaken. Comprising nearly 4500 high resolution polarised spectra of nearly 550 Galactic B and O-type stars, the MiMeS survey aims to address interesting and fundamental questions about the magnetism of hot, massive stars: How and when are massive star magnetic fields generated, and how do they evolve throughout stellar evolution? How do magnetic fields couple to and interact with the powerful winds of OB stars, and what are the consequences for the wind structure, momentum flux and energetics? What are the detailed physical mechanisms that lead to the anomalously slow rotation of many magnetic massive stars? What is the ultimate impact of stellar magnetic fields -- both direct and indirect -- on the evolution of massive stars? In this talk we report results from the analysis of the B-type stars observed within the MiMeS survey. The sample consists of over 450 stars ranging in spectral type from B9 to B0, and in evolutionary stage from the pre-main sequence to the post-main sequence. In addition to general statistical results concerning field incidence, strength and topology, we will elaborate our conclusions for subsamples of special interest, including the Herbig and classical Be stars, pulsating B stars and chemically peculiar B stars.

Glacier-derived permafrost ground ice, Bylot Island, Nunavut

NASA Astrophysics Data System (ADS)

Coulombe, S.; Fortier, D.; Lacelle, D.; Godin, E.; Veillette, A.

2014-12-01

Massive icy bodies are important components of permafrost geosystems. In situ freezing of water in the ground by ice-segregation processes forms most of these icy bodies. Other hypotheses for the origin of massive ice include the burial of ice (e.g. glacier, snow, lake, river, sea). The analysis of ground-ice characteristics can give numerous clues about the geomorphologic processes and the thermal conditions at the time when permafrost developed. Massive underground ice therefore shows a great potential as a natural archive of the earth's past climate. Identifying the origin of massive ice is a challenge for permafrost science since the different types of massive ice remain difficult to distinguish on the sole basis of field observations. There is actually no clear method to accurately assess the origin of massive ice and identification criteria need to be defined. The present study uses physico-chemical techniques to characterize buried glacier ice observed on Bylot Island, Nunavut. Combined to the analysis of cryostratigraphy, massive-ice cores crystallography and high-resolution imagery of the internal structure of the ice cores were obtained using micro-computed tomography techniques. These techniques are well suited for detailed descriptions (shape, size, orientation) of crystals, gas inclusions and sediment inclusions. Oxygen and hydrogen isotopes ratios of massive-ice cores were also obtained using common equilibrium technique. Preliminary results suggest the occurrence of two types of buried massive-ice of glacial origin similar to those found on contemporary glaciers: 1) Englacial ice: clear to whitish ice, with large crystals (cm) and abundant gas bubbles at crystal intersections; 2) Basal glacier ice: ice-rich, banded, micro-suspended to suspended cryostructures and ice-rich lenticular to layered cryostructures, with small ice crystals (mm) and a few disseminated gas bubbles. Glacier-derived permafrost contains antegenetic ice, which is ice that predates the aggradation of the permafrost. Remnants of glacier ice represent unique environmental archives and offer the possibility to reconstruct climate anterior to the formation of permafrost.

ASSET: Analysis of Sequences of Synchronous Events in Massively Parallel Spike Trains

PubMed Central

Canova, Carlos; Denker, Michael; Gerstein, George; Helias, Moritz

2016-01-01

With the ability to observe the activity from large numbers of neurons simultaneously using modern recording technologies, the chance to identify sub-networks involved in coordinated processing increases. Sequences of synchronous spike events (SSEs) constitute one type of such coordinated spiking that propagates activity in a temporally precise manner. The synfire chain was proposed as one potential model for such network processing. Previous work introduced a method for visualization of SSEs in massively parallel spike trains, based on an intersection matrix that contains in each entry the degree of overlap of active neurons in two corresponding time bins. Repeated SSEs are reflected in the matrix as diagonal structures of high overlap values. The method as such, however, leaves the task of identifying these diagonal structures to visual inspection rather than to a quantitative analysis. Here we present ASSET (Analysis of Sequences of Synchronous EvenTs), an improved, fully automated method which determines diagonal structures in the intersection matrix by a robust mathematical procedure. The method consists of a sequence of steps that i) assess which entries in the matrix potentially belong to a diagonal structure, ii) cluster these entries into individual diagonal structures and iii) determine the neurons composing the associated SSEs. We employ parallel point processes generated by stochastic simulations as test data to demonstrate the performance of the method under a wide range of realistic scenarios, including different types of non-stationarity of the spiking activity and different correlation structures. Finally, the ability of the method to discover SSEs is demonstrated on complex data from large network simulations with embedded synfire chains. Thus, ASSET represents an effective and efficient tool to analyze massively parallel spike data for temporal sequences of synchronous activity. PMID:27420734

Space-time philosophy reconstructed via massive Nordström scalar gravities? Laws vs. geometry, conventionality, and underdetermination

NASA Astrophysics Data System (ADS)

Pitts, J. Brian

2016-02-01

What if gravity satisfied the Klein-Gordon equation? Both particle physics from the 1920-30s and the 1890s Neumann-Seeliger modification of Newtonian gravity with exponential decay suggest considering a "graviton mass term" for gravity, which is algebraic in the potential. Unlike Nordström's "massless" theory, massive scalar gravity is strictly special relativistic in the sense of being invariant under the Poincaré group but not the 15-parameter Bateman-Cunningham conformal group. It therefore exhibits the whole of Minkowski space-time structure, albeit only indirectly concerning volumes. Massive scalar gravity is plausible in terms of relativistic field theory, while violating most interesting versions of Einstein's principles of general covariance, general relativity, equivalence, and Mach. Geometry is a poor guide to understanding massive scalar gravity(s): matter sees a conformally flat metric due to universal coupling, but gravity also sees the rest of the flat metric (barely or on long distances) in the mass term. What is the 'true' geometry, one might wonder, in line with Poincaré's modal conventionality argument? Infinitely many theories exhibit this bimetric 'geometry,' all with the total stress-energy's trace as source; thus geometry does not explain the field equations. The irrelevance of the Ehlers-Pirani-Schild construction to a critique of conventionalism becomes evident when multi-geometry theories are contemplated. Much as Seeliger envisaged, the smooth massless limit indicates underdetermination of theories by data between massless and massive scalar gravities-indeed an unconceived alternative. At least one version easily could have been developed before General Relativity; it then would have motivated thinking of Einstein's equations along the lines of Einstein's newly re-appreciated "physical strategy" and particle physics and would have suggested a rivalry from massive spin 2 variants of General Relativity (massless spin 2, Pauli and Fierz found in 1939). The Putnam-Grünbaum debate on conventionality is revisited with an emphasis on the broad modal scope of conventionalist views. Massive scalar gravity thus contributes to a historically plausible rational reconstruction of much of 20th-21st century space-time philosophy in the light of particle physics. An appendix reconsiders the Malament-Weatherall-Manchak conformal restriction of conventionality and constructs the 'universal force' influencing the causal structure. Subsequent works will discuss how massive gravity could have provided a template for a more Kant-friendly space-time theory that would have blocked Moritz Schlick's supposed refutation of synthetic a priori knowledge, and how Einstein's false analogy between the Neumann-Seeliger-Einstein modification of Newtonian gravity and the cosmological constant Λ generated lasting confusion that obscured massive gravity as a conceptual possibility.

Temperature structure and kinematics of the IRDC G035.39-00.33

NASA Astrophysics Data System (ADS)

Sokolov, Vlas; Wang, Ke; Pineda, Jaime E.; Caselli, Paola; Henshaw, Jonathan D.; Tan, Jonathan C.; Fontani, Francesco; Jiménez-Serra, Izaskun; Lim, Wanggi

2017-10-01

Aims: Infrared dark clouds represent the earliest stages of high-mass star formation. Detailed observations of their physical conditions on all physical scales are required to improve our understanding of their role in fueling star formation. Methods: We investigate the large-scale structure of the IRDC G035.39-00.33, probing the dense gas with the classical ammonia thermometer. This allows us to put reliable constraints on the temperature of the extended, pc-scale dense gas reservoir and to probe the magnitude of its non-thermal motions. Available far-infrared observations can be used in tandem with the observed ammonia emission to estimate the total gas mass contained in G035.39-00.33. Results: We identify a main velocity component as a prominent filament, manifested as an ammonia emission intensity ridge spanning more than 6 pc, consistent with the previous studies on the Northern part of the cloud. A number of additional line-of-sight components are found, and a large-scale linear velocity gradient of 0.2km s-1 pc-1 is found along the ridge of the IRDC. In contrast to the dust temperature map, an ammonia-derived kinetic temperature map, presented for the entirety of the cloud, reveals local temperature enhancements towards the massive protostellar cores. We show that without properly accounting for the line of sight contamination, the dust temperature is 2-3 K larger than the gas temperature measured with NH3. Conclusions: While both the large-scale kinematics and temperature structure are consistent with that of starless dark filaments, the kinetic gas temperature profile on smaller scales is suggestive of tracing the heating mechanism coincident with the locations of massive protostellar cores. The reduced spectral cubes (FITS format) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/606/A133

Fast ray-tracing algorithm for circumstellar structures (FRACS). II. Disc parameters of the B[e] supergiant CPD-57°,2874 from VLTI/MIDI data

NASA Astrophysics Data System (ADS)

Domiciano de Souza, A.; Bendjoya, P.; Niccolini, G.; Chesneau, O.; Borges Fernandes, M.; Carciofi, A. C.; Spang, A.; Stee, P.; Driebe, T.

2011-01-01

Context. B[e] supergiants are luminous, massive post-main sequence stars exhibiting non-spherical winds, forbidden lines, and hot dust in a disc-like structure. The physical properties of their rich and complex circumstellar environment (CSE) are not well understood, partly because these CSE cannot be easily resolved at the large distances found for B[e] supergiants (typically ⪆1 kpc). Aims: From mid-IR spectro-interferometric observations obtained with VLTI/MIDI we seek to resolve and study the CSE of the Galactic B[e] supergiant CPD-57° 2874. Methods: For a physical interpretation of the observables (visibilities and spectrum) we use our ray-tracing radiative transfer code (FRACS), which is optimised for thermal spectro-interferometric observations. Results: Thanks to the short computing time required by FRACS (<10 s per monochromatic model), best-fit parameters and uncertainties for several physical quantities of CPD-57° 2874 were obtained, such as inner dust radius, relative flux contribution of the central source and of the dusty CSE, dust temperature profile, and disc inclination. Conclusions: The analysis of VLTI/MIDI data with FRACS allowed one of the first direct determinations of physical parameters of the dusty CSE of a B[e] supergiant based on interferometric data and using a full model-fitting approach. In a larger context, the study of B[e] supergiants is important for a deeper understanding of the complex structure and evolution of hot, massive stars. Based on VLTI/MIDI observations collected at the European Southern Observatory (ESO), Paranal, Chile under ESO Programmes 074.D-0101 and 078.D-0213. Also based on observations at the ESO 2.2-m telescope, La Silla, Chile, under agreement with the Observatório Nacional-MCT (Brazil).Figure 5 is only available in electronic form at http://www.aanda.org

Quantitative estimation of massive gas hydrate in gas chimney structures, the eastern margin of Japan Sea, from the physical property anomalies obtained by LWD.

NASA Astrophysics Data System (ADS)

Tanahashi, M.; Morita, S.; Matsumoto, R.

2017-12-01

Two dedicated LWD (Logging While Drilling) cruises, GR14 and HR15, were conducted in summers of 2014 and 2015, respectively, by Meiji University and Geological Survey of Japan, AIST to explore the gas chimney structures, which are characterized by the columnar acoustic blanking below the topographic mound and/or pockmarks in eastern margin of Japan Sea. Shallow (33 to 172m-bsf, average 136m-bsf) 33 LWD drillings were carried out generally in and around gas chimney structures which are in Oki Trough, Off-Joetsu, and Mogami Trough areas, eastern margin of Japan Sea, during two cruises. Schlumberger LWD tools, GeoVISION (resistivity), TeleScope, ProVISION (NMR) and SonicVISION (sonic) were applied during GR14. NeoScope (neutron) was added and SonicScope was replaced for SonicVISION during HR15. The presence of thick highly-anomalous intervals within the LWD data at site J24L suggests the development of massive gas hydrate within Off-Joetsu, by very high resistivity ( 10,000 Ωm), high Vp ( 3,700 m/s) and Vs (370-1,839 m/s), high neutron porosity ( 1.2), low natural gamma ray intensity ( 0 API), low neutron gamma density ( 0.8 g/cm3), low NMR porosity ( 0.0), low permeability (10-2-10-4 mD), low formation neutron sigma (26-28). The extreme physical properties intervals suggest the development of the almost pure hydrate. Because of the clear contrast between pure hydrate and seawater saturated fine sediments, the hydrate amount can be estimated quantitatively based on the assumptions as the two component system of pure hydrate and the monotonous seawater saturated fine sediments. This study was conducted as a part of the methane hydrate research project funded by METI (the Ministry of Economy, Trade and Industry, Japan).

Properties and spatial distribution of galaxy superclusters

NASA Astrophysics Data System (ADS)

Liivamägi, Lauri Juhan

2017-01-01

Astronomy is a science that can offer plenty of unforgettable imagery, and the large-scale distribution of galaxies is no exception. Among the first features the viewer's eye is likely to be drawn to, are large concentrations of galaxies - galaxy superclusters, contrasting to the seemingly empty regions beside them. Superclusters can extend from tens to over hundred megaparsecs, they contain from hundreds to thousands of galaxies, and many galaxy groups and clusters. Unlike galaxy clusters, superclusters are clearly unrelaxed systems, not gravitationally bound as crossing times exceed the age of the universe, and show little to no radial symmetry. Superclusters, as part of the large-scale structure, are sensitive to the initial power spectrum and the following evolution. They are massive enough to leave an imprint on the cosmic microwave background radiation. Superclusters can also provide an unique environment for their constituent galaxies and galaxy clusters. In this study we used two different observational and one simulated galaxy samples to create several catalogues of structures that, we think, correspond to what are generally considered galaxy superclusters. Superclusters were delineated as continuous over-dense regions in galaxy luminosity density fields. When calculating density fields several corrections were applied to remove small-scale redshift distortions and distance-dependent selection effects. Resulting catalogues of objects display robust statistical properties, showing that flux-limited galaxy samples can be used to create nearly volume-limited catalogues of superstructures. Generally, large superclusters can be regarded as massive, often branching filamentary structures, that are mainly characterised by their length. Smaller superclusters, on the other hand, can display a variety of shapes. Spatial distribution of superclusters shows large-scale variations, with high-density concentrations often found in semi-regularly spaced groups. Future studies are needed to quantify the relations between superclusters and finer details of the galaxy distribution. Supercluster catalogues from this thesis have already been used in numerous other studies.

Software Applications on the Peregrine System | High-Performance Computing

Science.gov Websites

programming and optimization. Gaussian Chemistry Program for calculating molecular electronic structure and Materials Science Open-source classical molecular dynamics program designed for massively parallel systems framework Q-Chem Chemistry ab initio quantum chemistry package for predictin molecular structures

Channel Estimation and Pilot Design for Massive MIMO Systems with Block-Structured Compressive Sensing

NASA Astrophysics Data System (ADS)

Lv, ZhuoKai; Yang, Tiejun; Zhu, Chunhua

2018-03-01

Through utilizing the technology of compressive sensing (CS), the channel estimation methods can achieve the purpose of reducing pilots and improving spectrum efficiency. The channel estimation and pilot design scheme are explored during the correspondence under the help of block-structured CS in massive MIMO systems. The block coherence property of the aggregate system matrix can be minimized so that the pilot design scheme based on stochastic search is proposed. Moreover, the block sparsity adaptive matching pursuit (BSAMP) algorithm under the common sparsity model is proposed so that the channel estimation can be caught precisely. Simulation results are to be proved the proposed design algorithm with superimposed pilots design and the BSAMP algorithm can provide better channel estimation than existing methods.

Balancing Newtonian gravity and spin to create localized structures

NASA Astrophysics Data System (ADS)

Bush, Michael; Lindner, John

2015-03-01

Using geometry and Newtonian physics, we design localized structures that do not require electromagnetic or other forces to resist implosion or explosion. In two-dimensional Euclidean space, we find an equilibrium configuration of a rotating ring of massive dust whose inward gravity is the centripetal force that spins it. We find similar solutions in three-dimensional Euclidean and hyperbolic spaces, but only in the limit of vanishing mass. Finally, in three-dimensional Euclidean space, we generalize the two-dimensional result by finding an equilibrium configuration of a spherical shell of massive dust that supports itself against gravitational collapse by spinning isoclinically in four dimensions so its three-dimensional acceleration is everywhere inward. These Newtonian ``atoms'' illuminate classical physics and geometry.

Simulation of an array-based neural net model

NASA Technical Reports Server (NTRS)

Barnden, John A.

1987-01-01

Research in cognitive science suggests that much of cognition involves the rapid manipulation of complex data structures. However, it is very unclear how this could be realized in neural networks or connectionist systems. A core question is: how could the interconnectivity of items in an abstract-level data structure be neurally encoded? The answer appeals mainly to positional relationships between activity patterns within neural arrays, rather than directly to neural connections in the traditional way. The new method was initially devised to account for abstract symbolic data structures, but it also supports cognitively useful spatial analogue, image-like representations. As the neural model is based on massive, uniform, parallel computations over 2D arrays, the massively parallel processor is a convenient tool for simulation work, although there are complications in using the machine to the fullest advantage. An MPP Pascal simulation program for a small pilot version of the model is running.

Structure of massive star forming clumps from the Red MSX Source Survey

NASA Astrophysics Data System (ADS)

Figura, Charles C.; Urquhart, J. S.; Morgan, L.

2014-01-01

We present ammonia (1,1) and (2,2) emission maps of 61 high-mass star forming regions drawn from the Red MSX Source (RMS) Survey and observed with the Green Bank Telescope's K-Band Focal Plane Array. We use these observations to investigate the spatial distribution of the environmental conditions associated with this sample of embedded massive young stellar objects (MYSOs). Ammonia is an excellent high-density tracer of star-forming regions as its hyperfine structure allows relatively simple characterisation of the molecular environment. These maps are used to measure the column density, kinetic gas temperature distributions and velocity structure across these regions. We compare the distribution of these properties to that of the associated dust and mid-infrared emission traced by the ATLASGAL 870 micron emission maps and the Spitzer GLIMPSE IRAC images. We present a summary of these results and highlight some of more interesting finds.

Crystal MD: The massively parallel molecular dynamics software for metal with BCC structure

NASA Astrophysics Data System (ADS)

Hu, Changjun; Bai, He; He, Xinfu; Zhang, Boyao; Nie, Ningming; Wang, Xianmeng; Ren, Yingwen

2017-02-01

Material irradiation effect is one of the most important keys to use nuclear power. However, the lack of high-throughput irradiation facility and knowledge of evolution process, lead to little understanding of the addressed issues. With the help of high-performance computing, we could make a further understanding of micro-level-material. In this paper, a new data structure is proposed for the massively parallel simulation of the evolution of metal materials under irradiation environment. Based on the proposed data structure, we developed the new molecular dynamics software named Crystal MD. The simulation with Crystal MD achieved over 90% parallel efficiency in test cases, and it takes more than 25% less memory on multi-core clusters than LAMMPS and IMD, which are two popular molecular dynamics simulation software. Using Crystal MD, a two trillion particles simulation has been performed on Tianhe-2 cluster.

Structural Health Management for Future Aerospace Vehicles

NASA Technical Reports Server (NTRS)

Prosser, W. H.; Allison, S. G.; Woodard, S. E.; Wincheski, R. A.; Cooper, E. G.; Price, D. C.; Hedley, M.; Prokopenko, M.; Scott, D. A.; Tessler, A.

2004-01-01

Structural Health Management (SHM) will be of critical importance to provide the safety, reliability and affordability necessary for the future long duration space missions described in America's Vision for Space Exploration. Long duration missions to the Moon, Mars and beyond cannot be accomplished with the current paradigm of periodic, ground based structural integrity inspections. As evidenced by the Columbia tragedy, this approach is also inadequate for the current Shuttle fleet, thus leading to its initial implementation of on-board SHM sensing for impact detection as part of the return to flight effort. However, future space systems, to include both vehicles as well as structures such as habitation modules, will require an integrated array of onboard in-situ sensing systems. In addition, advanced data systems architectures will be necessary to communicate, store and process massive amounts of SHM data from large numbers of diverse sensors. Further, improved structural analysis and design algorithms will be necessary to incorporate SHM sensing into the design and construction of aerospace structures, as well as to fully utilize these sensing systems to provide both diagnosis and prognosis of structural integrity. Ultimately, structural integrity information will feed into an Integrated Vehicle Health Management (IVHM) system that will provide real-time knowledge of structural, propulsion, thermal protection and other critical systems for optimal vehicle management and mission control. This paper will provide an overview of NASA research and development in the area of SHM as well as to highlight areas of technology improvement necessary to meet these future mission requirements.

General of the Army George C. Marshall’s Strategic Leadership

DTIC Science & Technology

2017-03-15

coordinate organizational activities… structure tasks, engage in planning, build vision, acquire resources to achieve goals, manage crises, personal...organization while initiating massive changes in organizational structure and ideology in spite of conflicting traditions and preferences. His enabling...immediately upon taking the position, Marshall realized that an antiquated organizational structure interfered with daily operations. He told his

News

NASA Astrophysics Data System (ADS)

2001-09-01

EPS AWARD WINNERS Award for outreach to Physics Education authors; TEACHER TRAINING Helping teachers specialize in physics; AAPT SUMMER MEETING The science of light; AAPT SUMMER MEETING Do you believe in skepticism?; E-LEARNING Massive investment in Swedish online learning; UK SCIENCE YEAR News from Science Year; 11-16 CURRICULUM Naming the energy parts; TEACHER TRAINING Electronic Discussion Group for Trainee Teachers; PUBLICATIONS Physics on Course 2002; WALES Physics in Powys; HIGHER EDUCATION HE solutions to the physics teacher shortage; SCOTLAND The 27th Scottish Stirling Meeting; NORTHERN IRELAND Belfast physics teachers' meeting; SCOTLAND Physics Summer School, Edinburgh 2001; AAPT SUMMER MEETING Physics education research: massive growth; AAPT SUMMER MEETING Just-In-Time Teaching;

Stability of metal-rich very massive stars

NASA Astrophysics Data System (ADS)

Goodman, J.; White, Christopher J.

2016-02-01

We revisit the stability of very massive non-rotating main-sequence stars at solar metallicity, with the goal of understanding whether radial pulsations set a physical upper limit to stellar mass. Models of up to 938 solar masses are constructed with the MESA code, and their linear stability in the fundamental mode, assumed to be the most dangerous, is analysed with a fully non-adiabatic method. Models above 100 M⊙ have extended tenuous atmospheres (`shelves') that affect the stability of the fundamental. Even when positive, this growth rate is small, in agreement with previous results. We argue that small growth rates lead to saturation at small amplitudes that are not dangerous to the star. A mechanism for saturation is demonstrated involving non-linear parametric coupling to short-wavelength g-modes and the damping of the latter by radiative diffusion. The shelves are subject to much more rapidly growing strange modes. This also agrees with previous results but is extended here to higher masses. The strange modes probably saturate via shocks rather than mode coupling but have very small amplitudes in the core, where almost all of the stellar mass resides. Although our stellar models are hydrostatic, the structure of their outer parts suggests that optically thick winds, driven by some combination of radiation pressure, transonic convection, and strange modes, are more likely than pulsation in the fundamental mode to limit the main-sequence lifetime.

A CityGML Extension for Handling Very Large Tins

NASA Astrophysics Data System (ADS)

Kumar, K.; Ledoux, H.; Stoter, J.

2016-10-01

In addition to buildings, the terrain forms an important part of a 3D city model. Although in GIS terrains are usually represented with 2D grids, TINs are also increasingly being used in practice. One example is 3DTOP10NL, the 3D city model covering the whole of the Netherlands, which stores the relief with a constrained TIN containing more than 1 billion triangles. Due to the massive size of such datasets, the main problem that arises is: how to efficiently store and maintain them? While CityGML supports the storage of TINs, we argue in this paper that the current solution is not adequate. For instance, the 1 billion+ triangles of 3DTOP10NL require 686 GB of storage space with CityGML. Furthermore, the current solution does not store the topological relationships of the triangles, and also there are no clear mechanisms to handle several LODs. We propose in this paper a CityGML extension for the compact representation of terrains. We describe our abstract and implementation specifications (modelled in UML), and our prototype implementation to convert TINs to our CityGML structure. It increases the topological relationships that are explicitly represented, and allows us to compress up to a factor of ∼ 25 in our experiments with massive real-world terrains (more than 1 billion triangles).

The Eta Carinae Homunculus in Full 3D with X-Shooter and Shape

NASA Technical Reports Server (NTRS)

Steffen, Wolfgang; Teodoro, Mairan; Madura, Thomas I.; Groh, Jose H.; Gull, Theodore R.; Mehner, Andrea; Corcoran, Michael F.; Damineli, Augusto; Hamaguchi, Kenji

2014-01-01

Massive stars like Eta Carinae are extremely rare in comparison to stars such as the Sun, and currently we know of only a handful of stars with masses of more than 100 solar mass in the Milky Way. Such massive stars were much more frequent in the early history of the Universe and had a huge impact on its evolution. Even among this elite club, Eta Car is outstanding, in particular because of its giant eruption around 1840 that produced the beautiful bipolar nebula now known as the Homunculus. In this study, we used detailed spatio-kinematic information obtained from X-shooter spectra to reconstruct the 3D structure of the Homunculus. The small-scale features suggest that the central massive binary played a significant role in shaping the Homunculus.

Aerial View: SLS Intertank Arrives at Marshall for Critical Structural Testing

NASA Image and Video Library

2018-03-08

A structural test version of the intertank for NASA's new deep-space rocket, the Space Launch System, arrives at NASA’s Marshall Space Flight Center in Huntsville, Alabama, March 4, aboard the barge Pegasus. The intertank is the second piece of structural hardware for the massive SLS core stage built at NASA's Michoud Assembly Facility in New Orleans delivered to Marshall for testing. The structural test article will undergo critical testing as engineers push, pull and bend the hardware with millions of pounds of force to ensure it can withstand the forces of launch and ascent. The test hardware is structurally identical to the flight version of the intertank that will connect the core stage's two colossal propellant tanks, serve as the upper-connection point for the two solid rocket boosters and house critical avionics and electronics. Pegasus, originally used during the Space Shuttle Program, has been redesigned and extended to accommodate the SLS rocket's massive, 212-foot-long core stage -- the backbone of the rocket. The 310-foot-long barge will ferry the flight core stage from Michoud to other NASA centers for tests and launch.

Lorentz Invariance Violation effects on UHECR propagation: A geometrized approach

NASA Astrophysics Data System (ADS)

Torri, Marco Danilo Claudio; Bertini, Stefano; Giammarchi, Marco; Miramonti, Lino

2018-06-01

We explore the possibility to geometrize the interaction of massive fermions with the quantum structure of space-time, trying to create a theoretical background, in order to explain what some recent experimental results seem to implicate on the propagation of Ultra High Energy Cosmic Rays (UHECR). We will investigate part of the phenomenological implications of this approach on the predicted effect of the UHECR suppression, in fact recent evidences seem to involve the modification of the GZK cut-off phenomenon. The search for an effective theory, which can explain this physical effect, is based on Lorentz Invariance Violation (LIV), which is introduced via Modified Dispersion Relations (MDRs). Furthermore we illustrate that this perspective implies a more general geometry of space-time than the usual Riemannian one, indicating, for example, the opportunity to resort to Finsler theory.

Linguistic Structures in Stereotyped Aphasic Speech

ERIC Educational Resources Information Center

Buckingham, Hugh W., Jr.; And Others

1975-01-01

The linguistic structure of specific introductory type clauses, which appear at a relatively high frequency in the utterances of a severely brain damaged fluent aphasic with neologistic jargon speech, is examined. The analysis is restricted to one fifty-six-year-old male patient who suffered massive subdural hematoma. (SCC)

Formation of Very Young Massive Clusters and Implications for Globular Clusters

NASA Astrophysics Data System (ADS)

Banerjee, Sambaran; Kroupa, Pavel

How Very Young Massive star Clusters (VYMCs; also known as "starburst" clusters), which typically are of ≳ 104 M ⊙ and are a few Myr old, form out of Giant Molecular Clouds is still largely an open question. Increasingly detailed observations of young star clusters and star-forming molecular clouds and computational studies provide clues about their formation scenarios and the underlying physical processes involved. This chapter is focused on reviewing the decade-long studies that attempt to computationally reproduce the well-observed nearby VYMCs, such as the Orion Nebula Cluster, R136 and NGC 3603 young cluster, thereby shedding light on birth conditions of massive star clusters, in general. On this regard, focus is given on direct N-body modelling of real-sized massive star clusters, with a monolithic structure and undergoing residual gas expulsion, which have consistently reproduced the observed characteristics of several VYMCs and also of young star clusters, in general. The connection of these relatively simplified model calculations with the structural richness of dense molecular clouds and the complexity of hydrodynamic calculations of star cluster formation is presented in detail. Furthermore, the connections of such VYMCs with globular clusters, which are nearly as old as our Universe, is discussed. The chapter is concluded by addressing long-term deeply gas-embedded (at least apparently) and substructured systems like W3 Main. While most of the results are quoted from existing and up-to-date literature, in an integrated fashion, several new insights and discussions are provided.

"MASSIVE" brain dataset: Multiple acquisitions for standardization of structural imaging validation and evaluation.

PubMed

Froeling, Martijn; Tax, Chantal M W; Vos, Sjoerd B; Luijten, Peter R; Leemans, Alexander

2017-05-01

In this work, we present the MASSIVE (Multiple Acquisitions for Standardization of Structural Imaging Validation and Evaluation) brain dataset of a single healthy subject, which is intended to facilitate diffusion MRI (dMRI) modeling and methodology development. MRI data of one healthy subject (female, 25 years) were acquired on a clinical 3 Tesla system (Philips Achieva) with an eight-channel head coil. In total, the subject was scanned on 18 different occasions with a total acquisition time of 22.5 h. The dMRI data were acquired with an isotropic resolution of 2.5 mm 3 and distributed over five shells with b-values up to 4000 s/mm 2 and two Cartesian grids with b-values up to 9000 s/mm 2 . The final dataset consists of 8000 dMRI volumes, corresponding B 0 field maps and noise maps for subsets of the dMRI scans, and ten three-dimensional FLAIR, T 1 -, and T 2 -weighted scans. The average signal-to-noise-ratio of the non-diffusion-weighted images was roughly 35. This unique set of in vivo MRI data will provide a robust framework to evaluate novel diffusion processing techniques and to reliably compare different approaches for diffusion modeling. The MASSIVE dataset is made publically available (both unprocessed and processed) on www.massive-data.org. Magn Reson Med 77:1797-1809, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Massive collisions in debris disks: possible application to the beta Pic disc

NASA Astrophysics Data System (ADS)

Kral, Q.; Thébault, P.; Augereau, J.-C.; Boccaletti, A.; Charnoz, S.

2014-09-01

The new LIDT-DD code has been used to study massive collisions in debris discs. This new hybrid model is a fully self-consistent code coupling dynamics and collisions to study debris discs (Kral et al. 2013). It models the full complexity of debris discs' physics such as high velocity collisions, radiation-pressure affected orbits, wide range of grains' dynamical behaviour, etc. LIDT-DD can be used on many possible applications. Our first test case concerns the violent breakup of a massive planetesimal such as the ones happening during the late stages of planetary formation or with the biggest bodies in debris belts. We investigate the duration, magnitude and spatial structure of the signature left by such a violent event, as well as its observational detectability. We find that the breakup of a Ceres-sized body creates an asymmetric dust disc that is homogenized, by the coupled action of collisions and dynamics. The luminosity excess in the breakup's aftermath should be detectable by mid-IR photometry, from a 30 pc distance. As for the asymmetric structures, we derive synthetic images for the SPHERE/VLT and MIRI/JWST instruments, showing that they should be clearly visible and resolved from a 10 pc distance. We explain the observational signature of such impacts and give scaling laws to extrapolate our results to different configurations. These first results confirm that our code can be used to study the massive collision scenario to explain some asymmetries in the Beta-Pic disc.

The Correspondence between Convergence Peaks from Weak Lensing and Massive Dark Matter Haloes

NASA Astrophysics Data System (ADS)

Wei, Chengliang; Li, Guoliang; Kang, Xi; Liu, Xiangkun; Fan, Zuhui; Yuan, Shuo; Pan, Chuzhong

2018-05-01

The convergence peaks, constructed from galaxy shape measurement in weak lensing, is a powerful probe of cosmology as the peaks can be connected with the underlined dark matter haloes. However the capability of convergence peak statistic is affected by the noise in galaxy shape measurement, signal to noise ratio as well as the contribution from the projected mass distribution from the large-scale structures along the line of sight (LOS). In this paper we use the ray-tracing simulation on a curved sky to investigate the correspondence between the convergence peak and the dark matter haloes at the LOS. We find that, in case of no noise and for source galaxies at zs = 1, more than 65% peaks with SNR ≥ 3 (signal to noise ratio) are related to more than one massive haloes with mass larger than 1013M⊙. Those massive haloes contribute 87.2% to high peaks (SNR ≥ 5) with the remaining contributions are from the large-scale structures. On the other hand, the peaks distribution is skewed by the noise in galaxy shape measurement, especially for lower SNR peaks. In the noisy field where the shape noise is modelled as a Gaussian distribution, about 60% high peaks (SNR ≥ 5) are true peaks and the fraction decreases to 20% for lower peaks (3 ≤ SNR < 5). Furthermore, we find that high peaks (SNR ≥ 5) are dominated by very massive haloes larger than 1014M⊙.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bianchi, Luciana; Efremova, Boryana; Hodge, Paul

We present a comprehensive study of young stellar populations in six dwarf galaxies in or near the Local Group: Phoenix, Pegasus, Sextans A, Sextans B, WLM, and NGC 6822. Their star-forming regions, selected from GALEX wide-field far-UV imaging, were imaged (at sub-pc resolution) with the WFPC2 camera on board the Hubble Space Telescope (HST) in six bandpasses from far-UV to I to detect and characterize their hot massive star content. This study is part of HST treasury survey program HST-GO-11079; the general data characteristics and reduction procedures are detailed in this paper and results are presented for the first sixmore » galaxies. From a total of 180 HST images, we provide catalogs of the multi-band stellar photometry and derive the physical parameters of massive stars by analyzing it with model-atmosphere colors. We use the results to infer ages, number of massive stars, extinction, and spatial characteristics of the young stellar populations. The hot massive star content varies largely across our galaxy sample, from an inconspicuous presence in Phoenix and Pegasus to the highest relative abundance of young massive stars in Sextans A and WLM. Albeit to a largely varying extent, most galaxies show a very young population (a few Myrs, except for Phoenix), and older ones (a few 10{sup 7} years in Sextans A, Sextans B, NGC 6822, and WLM, {approx}10{sup 8}yr in Phoenix and Pegasus), suggesting discrete bursts of recent star formation in the mapped regions. The hot massive star content (indicative of the young populations) broadly correlates with the total galaxy stellar mass represented by the integrated optical magnitude, although it varies by a factor of {approx}3 between Sextans A, WLM, and Sextans B, which have similar M{sub V}. Extinction properties are also derived.« less

Congenital nephrotic syndrome.

PubMed

Hamed, Radi Ma

2003-01-01

The congenital nephrotic syndrome (CNS) is an uncommon disorder with onset of the nephrotic syndrome usually in the first three months of life. Several different diseases may cause the syndrome. These may be inherited, sporadic, acquired or part of a general malformation syndrome. The clinical course is marked by failure to thrive, recurrent life threatening bacterial infections, and early death from sepsis and/or uremia. A characteristic phenotype may be seen in children with CNS. The majority of reported cases of CNS are of the Finnish type (CNF). Although the role of the glomerular basement membrane has been emphasized as the barrier for retaining plasma proteins, recent studies have clearly shown that the slit diaphragm is the structure most likely to be the barrier in the glomerular capillary wall. The gene (NPHS1) was shown to encode a novel protein that was termed nephrin, due to its specific location in the kidney filter barrier, where it seems to form a highly organized filter structure. Nephrin is a transmembrane protein that probably forms the main building block of an isoporous zipper-like slit diaphragm filter structure. Defects in nephrin lead to the abnormal or absent slit diaphragm resulting in massive proteinuria and renal failure.

Observational properties of massive black hole binary progenitors

NASA Astrophysics Data System (ADS)

Hainich, R.; Oskinova, L. M.; Shenar, T.; Marchant, P.; Eldridge, J. J.; Sander, A. A. C.; Hamann, W.-R.; Langer, N.; Todt, H.

2018-01-01

Context. The first directly detected gravitational waves (GW 150914) were emitted by two coalescing black holes (BHs) with masses of ≈ 36 M⊙ and ≈ 29 M⊙. Several scenarios have been proposed to put this detection into an astrophysical context. The evolution of an isolated massive binary system is among commonly considered models. Aims: Various groups have performed detailed binary-evolution calculations that lead to BH merger events. However, the question remains open as to whether binary systems with the predicted properties really exist. The aim of this paper is to help observers to close this gap by providing spectral characteristics of massive binary BH progenitors during a phase where at least one of the companions is still non-degenerate. Methods: Stellar evolution models predict fundamental stellar parameters. Using these as input for our stellar atmosphere code (Potsdam Wolf-Rayet), we compute a set of models for selected evolutionary stages of massive merging BH progenitors at different metallicities. Results: The synthetic spectra obtained from our atmosphere calculations reveal that progenitors of massive BH merger events start their lives as O2-3V stars that evolve to early-type blue supergiants before they undergo core-collapse during the Wolf-Rayet phase. When the primary has collapsed, the remaining system will appear as a wind-fed high-mass X-ray binary. Based on our atmosphere models, we provide feedback parameters, broad band magnitudes, and spectral templates that should help to identify such binaries in the future. Conclusions: While the predicted parameter space for massive BH binary progenitors is partly realized in nature, none of the known massive binaries match our synthetic spectra of massive BH binary progenitors exactly. Comparisons of empirically determined mass-loss rates with those assumed by evolution calculations reveal significant differences. The consideration of the empirical mass-loss rates in evolution calculations will possibly entail a shift of the maximum in the predicted binary-BH merger rate to higher metallicities, that is, more candidates should be expected in our cosmic neighborhood than previously assumed.

General relativistic effects in the structure of massive white dwarfs

NASA Astrophysics Data System (ADS)

Carvalho, G. A.; Marinho, R. M.; Malheiro, M.

2018-04-01

In this work we investigate the structure of white dwarfs using the Tolman-Oppenheimer-Volkoff equations and compare our results with those obtained from Newtonian equations of gravitation in order to put in evidence the importance of general relativity (GR) for the structure of such stars. We consider in this work for the matter inside white dwarfs two equations of state, frequently found in the literature, namely, the Chandrasekhar and Salpeter equations of state. We find that using Newtonian equilibrium equations, the radii of massive white dwarfs (M>1.3M_{⊙ }) are overestimated in comparison with GR outcomes. For a mass of 1.415M_{⊙ } the white dwarf radius predicted by GR is about 33% smaller than the Newtonian one. Hence, in this case, for the surface gravity the difference between the general relativistic and Newtonian outcomes is about 65%. We depict the general relativistic mass-radius diagrams as M/M_{⊙ }=R/(a+bR+cR^2+dR^3+kR^4), where a, b, c and d are parameters obtained from a fitting procedure of the numerical results and k=(2.08× 10^{-6}R_{⊙ })^{-1}, being R_{⊙ } the radius of the Sun in km. Lastly, we point out that GR plays an important role to determine any physical quantity that depends, simultaneously, on the mass and radius of massive white dwarfs.

THE THREE-DIMENSIONAL EVOLUTION TO CORE COLLAPSE OF A MASSIVE STAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Couch, Sean M.; Chatzopoulos, Emmanouil; Arnett, W. David

2015-07-20

We present the first three-dimensional (3D) simulation of the final minutes of iron core growth in a massive star, up to and including the point of core gravitational instability and collapse. We capture the development of strong convection driven by violent Si burning in the shell surrounding the iron core. This convective burning builds the iron core to its critical mass and collapse ensues, driven by electron capture and photodisintegration. The non-spherical structure and motion generated by 3D convection is substantial at the point of collapse, with convective speeds of several hundreds of km s{sup −1}. We examine the impactmore » of such physically realistic 3D initial conditions on the core-collapse supernova mechanism using 3D simulations including multispecies neutrino leakage and find that the enhanced post-shock turbulence resulting from 3D progenitor structure aids successful explosions. We conclude that non-spherical progenitor structure should not be ignored, and should have a significant and favorable impact on the likelihood for neutrino-driven explosions. In order to make simulating the 3D collapse of an iron core feasible, we were forced to make approximations to the nuclear network making this effort only a first step toward accurate, self-consistent 3D stellar evolution models of the end states of massive stars.« less

Animation: What makes up the Space Launch System’s massive core stage

NASA Image and Video Library

2017-04-24

NASA’s new rocket, the Space Launch System, will be the most powerful rocket ever built for deep-space missions. The 212-foot core stage is the largest rocket stage ever built and will fuel four RS-25 engines that will help launch SLS. This animation depicts the parts that make up the core stage and how these parts will be joined to form the entire stage. The five major parts include: the engine section, the hydrogen tank, the intertank, the liquid oxygen tank and the forward skirt.

New HST/STIS Spectroscopy of Massive Members of R136 in 30 Doradus

NASA Astrophysics Data System (ADS)

Bostroem, Kyra; Walborn, Nolan; Crowther, Paul; Caballero-Nieves, Saida; Lennon, Daniel; Maíz Apellániz, Jesús

2013-06-01

We display new (in some cases, the first ever) spatially resolved optical and UV spectroscopy of a number of early O-type stars in R136, the massive core cluster of 30 Doradus in the LMC. Some of them are of the earliest spectral types, O2-O3, which accompany the more luminous WN members that are the most massive stars known, near or exceeding 300~M_⊙ initially. These results are relevant to the very top of the IMF and to the structure and formation of starburst clusters. The data are from HST/STIS programs GO 12465/13052 (PI Crowther), in which the long slit was stepped across the inner 4 arcsec (1 parsec) of R136, yielding both optical photospheric and FUV stellar-wind spectra of at least 100 resolved members, many of them for the first time. The optical data were obtained at 4 epochs to support eventual radial-velocity detection of spectroscopic binaries. This program vitally complements the VLT-FLAMES Tarantula Survey of the wider stellar content of 30 Doradus, by adding that of the massive core cluster, which is inaccessible to such observations from the ground. These combined datasets will provide unprecedented information about massive stellar evolution and starbursts.

Near-Infrared Mass Loss Diagnostics for Massive Stars

NASA Technical Reports Server (NTRS)

Sonneborn, George; Bouret, J. C.

2010-01-01

Stellar wind mass loss is a key process which modifies surface abundances, luminosities, and other physical properties of hot, massive stars. Furthermore, mass loss has to be understood quantitatively in order to accurately describe and predict massive star evolution. Two urgent problems have been identified that challenge our understanding of line-driven winds, the so-called weak-wind problem and wind clumping. In both cases, mass-loss rates are drastically lower than theoretically expected (up to a factor 1001). Here we study how the expected spectroscopic capabilities of the James Webb Space Telescope (JWST), especially NIRSpec, could be used to significantly improve constraints on wind density structures (clumps) and deep-seated phenomena in stellar winds of massive stars, including OB, Wolf-Rayet and LBV stars. Since the IR continuum of objects with strong winds is formed in the wind, IR lines may sample different depths inside the wind than UV-optical lines and provide new information about the shape of the velocity field and clumping properties. One of the most important applications of IR line diagnostics will be the measurement of mass-loss rates in massive stars with very weak winds by means of the H I Bracket alpha line, which has been identified as one of the most promising diagnostics for this problem.

Distributed Compressive CSIT Estimation and Feedback for FDD Multi-User Massive MIMO Systems

NASA Astrophysics Data System (ADS)

Rao, Xiongbin; Lau, Vincent K. N.

2014-06-01

To fully utilize the spatial multiplexing gains or array gains of massive MIMO, the channel state information must be obtained at the transmitter side (CSIT). However, conventional CSIT estimation approaches are not suitable for FDD massive MIMO systems because of the overwhelming training and feedback overhead. In this paper, we consider multi-user massive MIMO systems and deploy the compressive sensing (CS) technique to reduce the training as well as the feedback overhead in the CSIT estimation. The multi-user massive MIMO systems exhibits a hidden joint sparsity structure in the user channel matrices due to the shared local scatterers in the physical propagation environment. As such, instead of naively applying the conventional CS to the CSIT estimation, we propose a distributed compressive CSIT estimation scheme so that the compressed measurements are observed at the users locally, while the CSIT recovery is performed at the base station jointly. A joint orthogonal matching pursuit recovery algorithm is proposed to perform the CSIT recovery, with the capability of exploiting the hidden joint sparsity in the user channel matrices. We analyze the obtained CSIT quality in terms of the normalized mean absolute error, and through the closed-form expressions, we obtain simple insights into how the joint channel sparsity can be exploited to improve the CSIT recovery performance.

Colliding Winds in Massive Binaries

NASA Astrophysics Data System (ADS)

Thaller, M. L.

1998-12-01

In close binary systems of massive stars, the individual stellar winds will collide and form a bow shock between the stars, which may have significant impact on the mass-loss and evolution of the system. The existence of such a shock can be established through orbital-phase related variations in the UV resonance lines and optical emission lines. High density regions near the shock will produce Hα and Helium I emission which can be used to map the mass-flow structure of the system. The shock front between the stars may influence the balance of mass-loss versus mass-transfer in massive binary evolution, as matter lost to one star due to Roche lobe overflow may hit the shock and be deflected before it can accrete onto the surface of the other star. I have completed a high-resolution spectroscopic survey of 37 massive binaries, and compared the incidence and strength of emission to an independent survey of single massive stars. Binary stars show a statistically significant overabundance of optical emission, especially when one of the binary stars is in either a giant or supergiant phase of evolution. Seven systems in my survey exhibited clear signs of orbital phase related emission, and for three of the stars (HD 149404, HD 152248, and HD 163181), I present qualitative models of the mass-flow dynamics of the systems.

The Prediction of Long-Term Thermal Aging in Cast Austenitic Stainless Steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byun, Thak Sang; Yang, Ying; Lach, Timothy G.

Cast austenitic stainless steel (CASS) materials are extensively used for many massive primary coolant system components of light water reactors (LWRs) including coolant piping, valve bodies, pump casings, and piping elbows. Many of these components are operated in complex and persistently damaging environments of elevated temperature, high pressure, corrosive environment, and sometimes radiation for long periods of time. Since a large number of CASS components are installed in every nuclear power plant and replacing such massive components is prohibitively expensive, any significant degradation in mechanical properties that affects structural integrity, cracking resistance in particular, of CASS components will raise amore » serious concern on the performance of entire power plant. The CASS materials for nuclear components are highly corrosion-resistant Fe-Cr-Ni alloys with 300 series stainless steel compositions and mostly austenite (γ)–ferrite (δ) duplex structures, which result from the casting processes consisting of alloy melting and pouring or injecting liquid metal into a static or spinning mold. Although the commonly used static and centrifugal casting processes enable the fabrication of massive components with proper resistance to environmental attacks, the alloying and microstructural conditions are not highly controllable in actual fabrication, especially in the casting processes of massive components. In the corrosion-resistant Fe-Cr-Ni alloy system, the minor phase (i.e., the δ-ferrite phase) is inevitably formed during the casting process, and is in a non-equilibrium state subject to detrimental changes during exposure to elevated temperature and/or radiation. In general, relatively few critical degradation modes are expected within the current design lifetime of 40 years, given that the CASS components have been processed properly. It has been well known, however, that both the thermal aging and the neutron irradiation can cause degradation of static and impact toughness in the cast stainless steels, and if combined with any flaws formed during the fabrication process or in service, the thermal degradation in CASS components can be a serious concern for the integrity of the power plant. On the integrity of the CASS components during the extended lifetime of 60 years or longer, no conclusive prediction has been possible, primarily because no direct experience with these materials currently exists, and the aging behavior of CASS alloys still remains largely uncertain. The ongoing research for CASS aging, as part of the LWRS Program/Materials Aging and Degradation Pathway, is an integrated research using holistic experimental and modeling means to provide both the scientific understanding on the aging and failure phenomena and the practical models to predict the degree of property degradation.« less

A plausible energy source and structure for quasi-stellar objects

NASA Technical Reports Server (NTRS)

Daltabuit, E.; Cox, D.

1972-01-01

If a collision of two large, massive, fast gas clouds occurs, their kinetic energy is converted to radiation in a pair of shock fronts at their interface. The resulting structure is described, and the relevance of this as a radiation source for quasi-stellar objects is considered.

A Structural Equation Modelling Approach for Massive Blended Synchronous Teacher Training

ERIC Educational Resources Information Center

Kannan, Kalpana; Narayanan, Krishnan

2015-01-01

This paper presents a structural equation modelling (SEM) approach for blended synchronous teacher training workshop. It examines the relationship among various factors that influence the Satisfaction (SAT) of participating teachers. Data were collected with the help of a questionnaire from about 500 engineering college teachers. These teachers…

X-RAY EMISSION LINE PROFILES FROM WIND CLUMP BOW SHOCKS IN MASSIVE STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ignace, R.; Waldron, W. L.; Cassinelli, J. P.

2012-05-01

The consequences of structured flows continue to be a pressing topic in relating spectral data to physical processes occurring in massive star winds. In a preceding paper, our group reported on hydrodynamic simulations of hypersonic flow past a rigid spherical clump to explore the structure of bow shocks that can form around wind clumps. Here we report on profiles of emission lines that arise from such bow shock morphologies. To compute emission line profiles, we adopt a two-component flow structure of wind and clumps using two 'beta' velocity laws. While individual bow shocks tend to generate double-horned emission line profiles,more » a group of bow shocks can lead to line profiles with a range of shapes with blueshifted peak emission that depends on the degree of X-ray photoabsorption by the interclump wind medium, the number of clump structures in the flow, and the radial distribution of the clumps. Using the two beta law prescription, the theoretical emission measure and temperature distribution throughout the wind can be derived. The emission measure tends to be power law, and the temperature distribution is broad in terms of wind velocity. Although restricted to the case of adiabatic cooling, our models highlight the influence of bow shock effects for hot plasma temperature and emission measure distributions in stellar winds and their impact on X-ray line profile shapes. Previous models have focused on geometrical considerations of the clumps and their distribution in the wind. Our results represent the first time that the temperature distribution of wind clump structures are explicitly and self-consistently accounted for in modeling X-ray line profile shapes for massive stars.« less

Magnetic Fields in the Massive Dense Cores of the DR21 Filament: Weakly Magnetized Cores in a Strongly Magnetized Filament

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ching, Tao-Chung; Lai, Shih-Ping; Zhang, Qizhou

We present Submillimeter Array 880 μ m dust polarization observations of six massive dense cores in the DR21 filament. The dust polarization shows complex magnetic field structures in the massive dense cores with sizes of 0.1 pc, in contrast to the ordered magnetic fields of the parsec-scale filament. The major axes of the massive dense cores appear to be aligned either parallel or perpendicular to the magnetic fields of the filament, indicating that the parsec-scale magnetic fields play an important role in the formation of the massive dense cores. However, the correlation between the major axes of the cores andmore » the magnetic fields of the cores is less significant, suggesting that during the core formation, the magnetic fields below 0.1 pc scales become less important than the magnetic fields above 0.1 pc scales in supporting a core against gravity. Our analysis of the angular dispersion functions of the observed polarization segments yields a plane-of-sky magnetic field strength of 0.4–1.7 mG for the massive dense cores. We estimate the kinematic, magnetic, and gravitational virial parameters of the filament and the cores. The virial parameters show that the gravitational energy in the filament dominates magnetic and kinematic energies, while the kinematic energy dominates in the cores. Our work suggests that although magnetic fields may play an important role in a collapsing filament, the kinematics arising from gravitational collapse must become more important than magnetic fields during the evolution from filaments to massive dense cores.« less

In Spite of National Awards, Recognition, Staff and Adviser Face "Paradox of the Worst Kind."

ERIC Educational Resources Information Center

Kovas, Marcia A.

1994-01-01

Describes how a journalism instructor/newspaper advisor and her students fought a proposal (part of massive course cuts) to cancel a national-award-winning journalism program. Notes early warning signs, and suggests preventive measures to preserve programs. (SR)

Solidarity outpatient clinics in Greece: a survey of a massive social movement.

PubMed

Evlampidou, Iro; Kogevinas, Manolis

2018-03-06

Until 2016, around 3 million persons had limited access to health care in Greece due to the economic crisis. We describe a massive solidarity movement of community clinics and pharmacies in Greece. We conducted a survey in 2014-15 and describe the characteristics of community clinics and pharmacies spontaneously established all over Greece after 2008. A characteristic of the 92 active solidarity clinics is autonomous collective functioning, free services, and funding from non-governmental sources. The largest clinics examined more than 500 uninsured or partly insured patients per month. Clinics covered a wide range of clinical and preventive services. Funding, availability of drugs, vaccines, medical material and their legal status were the main problems identified. The solidarity movement involved thousands of health professionals covering essential population needs. The community outpatient clinics were an outstanding example of solidarity and temporarily alleviated the health needs of a large part of the population. Copyright © 2018 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

A MASSIVE RUNAWAY STAR FROM 30 DORADUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, C. J.; Walborn, N. R.; Massa, D.

2010-06-01

We present the first ultraviolet (UV) and multi-epoch optical spectroscopy of 30 Dor 016, a massive O2-type star on the periphery of 30 Doradus in the Large Magellanic Cloud. The UV data were obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope as part of the Servicing Mission Observatory Verification program after Servicing Mission 4, and reveal no. 016 to have one of the fastest stellar winds known. From analysis of the C IV {lambda}{lambda}1548-51 doublet we find a terminal velocity, v {sub {infinity}} = 3450 {+-} 50 km s{sup -1}. Optical spectroscopy is from the VLT-FLAMES Tarantulamore » Survey, from which we rule out a massive companion (with 2 days < P < 1 yr) to a confidence of 98%. The radial velocity of no. 016 is offset from the systemic value by -85 km s{sup -1}, suggesting that the star has traveled the 120 pc from the core of 30 Doradus as a runaway, ejected via dynamical interactions.« less

Geology of the Brick Flat massive sulfide body, Iron Mountain cluster, West Shasta district, California ( USA).

USGS Publications Warehouse

Albers, J.P.

1985-01-01

The Brick Flat massive sulfide body is one of a group of 8 individual bodies that constitute the Iron Mountain cluster in the S part of the West Shasta district. Before they were separated by postmineral faulting, 5 of the 8 sulfide bodies formed a single large deposit about 1375 m long with a mass of some 23 million metric tons. The pyritic Brick Flat sulfide body is one of the 5 faulted segements of this deposit. The Brick Flat massive sulfide lies within medium phenocryst rhyolite that is characteristic of the ore-bearing middle unit of the Balaklala Rhyolite. It is interpreted to be downfaulted a vertical distance of 75 to 85 m from the Old Mine sulfide-gossan orebody along the N-dipping Camden South fault. It is bounded in turn on its N side by another parallel fault, the Camden North, which drops the orebody down another 75 m to the level of the Richmond orebody. -from Author

Non-thermal Processes in Colliding-wind Massive Binaries: the Contribution of Simbol-X to a Multiwavelength Investigation

NASA Astrophysics Data System (ADS)

De Becker, Michaël; Blomme, Ronny; Micela, Giusi; Pittard, Julian M.; Rauw, Gregor; Romero, Gustavo E.; Sana, Hugues; Stevens, Ian R.

2009-05-01

Several colliding-wind massive binaries are known to be non-thermal emitters in the radio domain. This constitutes strong evidence for the fact that an efficient particle acceleration process is at work in these objects. The acceleration mechanism is most probably the Diffusive Shock Acceleration (DSA) process in the presence of strong hydrodynamic shocks due to the colliding-winds. In order to investigate the physics of this particle acceleration, we initiated a multiwavelength campaign covering a large part of the electromagnetic spectrum. In this context, the detailed study of the hard X-ray emission from these sources in the SIMBOL-X bandpass constitutes a crucial element in order to probe this still poorly known topic of astrophysics. It should be noted that colliding-wind massive binaries should be considered as very valuable targets for the investigation of particle acceleration in a similar way as supernova remnants, but in a different region of the parameter space.

A NEWLY FORMING COLD FLOW PROTOGALACTIC DISK, A SIGNATURE OF COLD ACCRETION FROM THE COSMIC WEB

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, D. Christopher; Matuszewski, Mateusz; Morrissey, Patrick

How galaxies form from, and are fueled by, gas from the intergalactic medium (IGM) remains one of the major unsolved problems in galaxy formation. While the classical Cold Dark Matter paradigm posits galaxies forming from cooling virialized gas, recent theory and numerical simulations have highlighted the importance of cold accretion flows—relatively cool ( T ∼ few × 104 K) unshocked gas streaming along filaments into dark matter halos, including hot, massive, high-redshift halos. These flows are thought to deposit gas and angular momentum into the circumgalactic medium resulting in disk- or ring-like structures, eventually coalescing into galaxies forming at filamentarymore » intersections. We earlier reported a bright, Ly α emitting filament near the QSO HS1549+19 at redshift z = 2.843 discovered with the Palomar Cosmic Web Imager. We now report that the bright part of this filament is an enormous ( R > 100 kpc) rotating structure of hydrogen gas with a disk-like velocity profile consistent with a 4 × 10{sup 12} M {sub ⊙} halo. The orbital time of the outer part of the what we term a “protodisk” is comparable to the virialization time and the age of the universe at this redshift. We propose that this protodisk can only have recently formed from cold gas flowing directly from the cosmic web.« less

Hamiltonian vs Lagrangian Embedding of a Massive Spin-One Theory Involving Two-Form Field

NASA Astrophysics Data System (ADS)

Harikumar, E.; Sivakumar, M.

We consider the Hamiltonian and Lagrangian embedding of a first-order, massive spin-one, gauge noninvariant theory involving antisymmetric tensor field. We apply the BFV-BRST generalized canonical approach to convert the model to a first class system and construct nilpotent BFV-BRST charge and a unitarizing Hamiltonian. The canonical analysis of the Stückelberg formulation of this model is presented. We bring out the contrasting feature in the constraint structure, specifically with respect to the reducibility aspect, of the Hamiltonian and the Lagrangian embedded model. We show that to obtain manifestly covariant Stückelberg Lagrangian from the BFV embedded Hamiltonian, phase space has to be further enlarged and show how the reducible gauge structure emerges in the embedded model.

Modified gravity and the CMB

NASA Astrophysics Data System (ADS)

Brax, Philippe; Davis, Anne-Christine

2012-01-01

We consider the effect of modified gravity on the peak structure of the cosmic microwave background (CMB) spectrum. We focus on simple models of modified gravity mediated by a massive scalar field coupled to both baryons and cold dark matter. This captures the features of chameleon, symmetron, dilaton, and f(R) models. We find that the CMB peaks can be affected in three independent ways provided the Compton radius of the massive scalar is not far-off the sound horizon at last scattering. When the coupling of the massive scalar to cold dark matter is large, the anomalous growth of the cold dark matter perturbation inside the Compton radius induces a change in the peak amplitudes. When the coupling to baryons is moderately large, the speed of sound is modified and the peaks shifted to higher momenta. Finally when both couplings are nonvanishing, a new contribution proportional to the Newton potential appears in the Sachs-Wolfe temperature and increases the peak amplitudes. We also show how, given any temporal evolution of the scalar field mass, one can engineer a corresponding modified gravity model of the chameleon type. This opens up the possibility of having independent constraints on modified gravity from the CMB peaks and large scale structures at low redshifts.

Internal dark matter structure of the most massive galaxy clusters

NASA Astrophysics Data System (ADS)

Le Brun, A. M. C.; Arnaud, M.; Pratt, G. W.; Teyssier, R.

2018-01-01

We investigate the evolution of the dark matter density profiles of the most massive galaxy clusters in the Universe. Using a `zoom-in' procedure on a large suite of cosmological simulations of total comoving volume of 3 (h - 1 Gpc)3, we study the 25 most massive clusters in four redshift slices from z ˜ 1 to the present. The minimum mass is M500 > 5.5 × 1014 M⊙ at z = 1. Each system has more than two million particles within r500. Once scaled to the critical density at each redshift, the dark matter profiles within r500 are strikingly similar from z ˜ 1 to the present day, exhibiting a low dispersion of 0.15 dex, and showing little evolution with redshift in the radial logarithmic slope and scatter. They have the running power-law shape typical of the Navarro-Frenk-White type profiles, and their inner structure, resolved to 3.8 h-1 comoving kpc at z = 1, shows no signs of converging to an asymptotic slope. Our results suggest that this type of profile is already in place at z > 1 in the highest-mass haloes in the Universe, and that it remains exceptionally robust to merging activity.

Extended Reissner-Nordström solutions sourced by dynamical torsion

NASA Astrophysics Data System (ADS)

Cembranos, Jose A. R.; Valcarcel, Jorge Gigante

2018-04-01

We find a new exact vacuum solution in the framework of the Poincaré Gauge field theory with massive torsion. In this model, torsion operates as an independent field and introduces corrections to the vacuum structure present in General Relativity. The new static and spherically symmetric configuration shows a Reissner-Nordström-like geometry characterized by a spin charge. It extends the known massless torsion solution to the massive case. The corresponding Reissner-Nordström-de Sitter solution is also compatible with a cosmological constant and additional U (1) gauge fields.

Dubin calls on CMPA to eliminate fee differentials, adopt flat fee for all physicians.

PubMed

Sullivan, P

1997-03-01

Charles Dubin's massive review of the Canadian Medical Protective Association supports the CMPA's policy of maintaining a large reserve for malpractice coverage, but calls for a major overhaul of the association's fee structure. Regardless of the risks their practices pose, says Dubin, all doctors should pay the same fee in order to keep physicians practising in high-risk specialties such as obstetrics and orthopedic surgery. The alternative, said CMPA president Dr. Bill Thomas, is an exodus from certain specialties because of massive bills for malpractice insurance.

Translation invariant time-dependent massive gravity: Hamiltonian analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mourad, Jihad; Steer, Danièle A.; Noui, Karim, E-mail: mourad@apc.univ-paris7.fr, E-mail: karim.noui@lmpt.univ-tours.fr, E-mail: steer@apc.univ-paris7.fr

2014-09-01

The canonical structure of the massive gravity in the first order moving frame formalism is studied. We work in the simplified context of translation invariant fields, with mass terms given by general non-derivative interactions, invariant under the diagonal Lorentz group, depending on the moving frame as well as a fixed reference frame. We prove that the only mass terms which give 5 propagating degrees of freedom are the dRGT mass terms, namely those which are linear in the lapse. We also complete the Hamiltonian analysis with the dynamical evolution of the system.

A 1-D evolutionary model for icy satellites, applied to Enceladus

NASA Astrophysics Data System (ADS)

Prialnik, Dina; Malamud, Uri

2015-11-01

A 1-D long-term evolution code for icy satellites is presented, which couples multiple processes: water migration, geochemical reactions, water and silicate phase transitions, crystallization, compaction by self-gravity, and ablation. The code takes into account various energy sources: tidal heating, radiogenic heating, geochemical energy released by serpentinization or absorbed by mineral dehydration, gravitational energy, and insolation. It includes heat transport by conduction, convection, and advection.The code is applied to Enceladus, by guessing the initial conditions that would render a structure compatible with present-day observations, and adopting a homogeneous initial structure. Assuming that the satellite has been losing water continually along its evolution, it follows that it was formed as a more massive, more ice-rich and more porous object, and gradually transformed into its present day state, due to sustained tidal heating. Several initial compositions and evolution scenarios are considered, and the evolution is simulated for the age of the Solar System. The results corresponding to the present configuration are confronted with the available observational constraints. The present configuration is shown to be differentiated into a pure icy mantle, several tens of km thick, overlying a rocky core, composed of dehydrated rock in the central part and hydrated rock in the outer part. Such a differentiated structure is obtained not only for Enceladus, but for other medium size ice-rich bodies as well.Predictions for Enceladus are a higher rock/ice mass ratio than previously assumed, and a thinner ice mantle, compatible with recent estimates based on gravity field measurements. Although, obviously, the 1-D model cannot be used to explain local phenomena, it sheds light on the internal structure invoked in explanations of localized features and activities.

Extended High Circular Polarization in the Orion Massive Star Forming Region: Implications for the Origin of Homochirality in the Solar System

PubMed Central

Tamura, Motohide; Kandori, Ryo; Kusakabe, Nobuhiko; Hough, James H.; Bailey, Jeremy; Whittet, Douglas C. B.; Lucas, Philip W.; Nakajima, Yasushi; Hashimoto, Jun

2010-01-01

We present a wide-field (∼6′ × 6′) and deep near-infrared (Ks band: 2.14 μm) circular polarization image in the Orion nebula, where massive stars and many low-mass stars are forming. Our results reveal that a high circular polarization region is spatially extended (∼0.4 pc) around the massive star-forming region, the BN/KL nebula. However, other regions, including the linearly polarized Orion bar, show no significant circular polarization. Most of the low-mass young stars do not show detectable extended structure in either linear or circular polarization, in contrast to the BN/KL nebula. If our solar system formed in a massive star-forming region and was irradiated by net circularly polarized radiation, then enantiomeric excesses could have been induced, through asymmetric photochemistry, in the parent bodies of the meteorites and subsequently delivered to Earth. These could then have played a role in the development of biological homochirality on Earth. PMID:20213160

Relativistic N-body simulations with massive neutrinos

NASA Astrophysics Data System (ADS)

Adamek, Julian; Durrer, Ruth; Kunz, Martin

2017-11-01

Some of the dark matter in the Universe is made up of massive neutrinos. Their impact on the formation of large scale structure can be used to determine their absolute mass scale from cosmology, but to this end accurate numerical simulations have to be developed. Due to their relativistic nature, neutrinos pose additional challenges when one tries to include them in N-body simulations that are traditionally based on Newtonian physics. Here we present the first numerical study of massive neutrinos that uses a fully relativistic approach. Our N-body code, gevolution, is based on a weak-field formulation of general relativity that naturally provides a self-consistent framework for relativistic particle species. This allows us to model neutrinos from first principles, without invoking any ad-hoc recipes. Our simulation suite comprises some of the largest neutrino simulations performed to date. We study the effect of massive neutrinos on the nonlinear power spectra and the halo mass function, focusing on the interesting mass range between 0.06 eV and 0.3 eV and including a case for an inverted mass hierarchy.

Phosphatization Associated Features of Ferromanganese Crusts at Lemkein Seamount, Marshall Islands

NASA Astrophysics Data System (ADS)

Choi, J.; Lee, I.; Park, B. K.; Kim, J.

2014-12-01

Old layers of ferromanganese crusts, especially in the Pacific Ocean, have been affected by phosphatization. Ferromanganese crusts on Lemkein seamount in Marshall Islands also are phosphatized (3.3 to 4.2 wt % of P concentration). Furthermore, they have characteristic features that are different from other ferromanganese crusts. These features occur near the phosphorite, which were thought to fill the pore spaces of ferromanganese crusts. Inside the features, ferromanganese crusts are botryoidally precipitated from the round-boundary. The features of the phosphatized lower crusts of Lemkein seamount are observed using microscope and SEM. Elemental compositions of the selected samples were analyzed by SEM-EDS. Based on the observation and analysis of samples, three characteristic structures are identified: (1) phosphate-filled circles, (2) tongue-shaped framboidal crust, and (3) massive framboidal crust. The phosphate-filled circles are mostly composed of phosphorite, and they include trace fossils such as foraminifera. Phosphatized ferromanganese crusts exist at the boundary of this structure. The tongue-shaped crust is connected with the lips downward, and ferromanganese crusts inside the tongue show distinct growth rim. The massive framboidal crust is located below the tongue. Ferromanganese crusts in the massive framboidal crust are enveloped by phosphate, and some of the crusts are phosphatized. Around the structures, Mn oxide phase is concentrated as a shape of corona on BSE image. All of the structures are in the phosphatized crusts that show columnar growth of ferromanganese crusts and have sub-parallel lamination. These observation and chemical analysis of the ferromanganese crusts can provide a clue of diagenetic processes during the formation of ferromanganese crusts.

Neural Network of Predictive Motor Timing in the Context of Gender Differences

PubMed Central

Lošák, Jan; Kašpárek, Tomáš; Vaníček, Jiří; Bareš, Martin

2016-01-01

Time perception is an essential part of our everyday lives, in both the prospective and the retrospective domains. However, our knowledge of temporal processing is mainly limited to the networks responsible for comparing or maintaining specific intervals or frequencies. In the presented fMRI study, we sought to characterize the neural nodes engaged specifically in predictive temporal analysis, the estimation of the future position of an object with varying movement parameters, and the contingent neuroanatomical signature of differences in behavioral performance between genders. The established dominant cerebellar engagement offers novel evidence in favor of a pivotal role of this structure in predictive short-term timing, overshadowing the basal ganglia reported together with the frontal cortex as dominant in retrospective temporal processing in the subsecond spectrum. Furthermore, we discovered lower performance in this task and massively increased cerebellar activity in women compared to men, indicative of strategy differences between the genders. This promotes the view that predictive temporal computing utilizes comparable structures in the retrospective timing processes, but with a definite dominance of the cerebellum. PMID:27019753

Effect of Turbulence Models on Two Massively-Separated Benchmark Flow Cases

NASA Technical Reports Server (NTRS)

Rumsey, Christopher L.

2003-01-01

Two massively-separated flow cases (the 2-D hill and the 3-D Ahmed body) were computed with several different turbulence models in the Reynolds-averaged Navier-Stokes code CFL3D as part of participation in a turbulence modeling workshop held in Poitiers, France in October, 2002. Overall, results were disappointing, but were consistent with results from other RANS codes and other turbulence models at the workshop. For the 2-D hill case, those turbulence models that predicted separation location accurately ended up yielding a too-long separation extent downstream. The one model that predicted a shorter separation extent in better agreement with LES data did so only by coincidence: its prediction of earlier reattachment was due to a too-late prediction of the separation location. For the Ahmed body, two slant angles were computed, and CFD performed fairly well for one of the cases (the larger slant angle). Both turbulence models tested in this case were very similar to each other. For the smaller slant angle, CFD predicted massive separation, whereas the experiment showed reattachment about half-way down the center of the face. These test cases serve as reminders that state- of-the-art CFD is currently not a reliable predictor of massively-separated flow physics, and that further validation studies in this area would be beneficial.

Analytical study of a Kerr-Sen black hole and a charged massive scalar field

NASA Astrophysics Data System (ADS)

Bernard, Canisius

2017-11-01

It is reported that Kerr-Newman and Kerr-Sen black holes are unstable to perturbations of charged massive scalar field. In this paper, we study analytically the complex frequencies which characterize charged massive scalar fields in a near-extremal Kerr-Sen black hole. For near-extremal Kerr-Sen black holes and for charged massive scalar fields in the eikonal large-mass M ≫μ regime, where M is the mass of the black hole, and μ is the mass of the charged scalar field, we have obtained a simple expression for the dimensionless ratio ωI/(ωR-ωc) , where ωI and ωR are, respectively, the imaginary and real parts of the frequency of the modes, and ωc is the critical frequency for the onset of super-radiance. We have also found our expression is consistent with the result of Hod [Phys. Rev. D 94, 044036 (2016), 10.1103/PhysRevD.94.044036] for the case of a near-extremal Kerr-Newman black hole and the result of Zouros and Eardly [Ann. Phys. (N.Y.) 118, 139 (1979), 10.1016/0003-4916(79)90237-9] for the case of neutral scalar fields in the background of a near-extremal Kerr black hole.

On the optically thick winds of Wolf-Rayet stars

NASA Astrophysics Data System (ADS)

Gräfener, G.; Owocki, S. P.; Grassitelli, L.; Langer, N.

2017-12-01

Context. The classical Wolf-Rayet (WR) phase is believed to mark the end stage of the evolution of massive stars with initial masses higher than 25M⊙. Stars in this phase expose their stripped cores with the products of H- or He-burning at their surface. They develop strong, optically thick stellar winds that are important for the mechanical and chemical feedback of massive stars, and that determine whether the most massive stars end their lives as neutron stars or black holes. The winds of WR stars are currently not well understood, and their inclusion in stellar evolution models relies on uncertain empirical mass-loss relations. Aims: We investigate theoretically the mass-loss properties of H-free WR stars of the nitrogen sequence (WN stars). Methods: We connected stellar structure models for He stars with wind models for optically thick winds and assessed the degree to which these two types of models can simultaneously fulfil their respective sonic-point conditions. Results: Fixing the outer wind law and terminal wind velocity ν∞, we obtain unique solutions for the mass-loss rates of optically thick, radiation-driven winds of WR stars in the phase of core He-burning. The resulting mass-loss relations as a function of stellar parameters agree well with previous empirical relations. Furthermore, we encounter stellar mass limits below which no continuous solutions exist. While these mass limits agree with observations of WR stars in the Galaxy, they contradict observations in the LMC. Conclusions: While our results in particular confirm the slope of often-used empirical mass-loss relations, they imply that only part of the observed WN population can be understood in the framework of the standard assumptions of a smooth transonic flow and compact stellar core. This means that alternative approaches such as a clumped and inflated wind structure or deviations from the diffusion limit at the sonic point may have to be invoked. Qualitatively, the existence of mass limits for the formation of WR-type winds may be relevant for the non-detection of low-mass WR stars in binary systems, which are believed to be progenitors of Type Ib/c supernovae. The sonic-point conditions derived in this work may provide a possibility to include optically thick winds in stellar evolution models in a more physically motivated form than in current models.

Heavy-quark production in gluon fusion at two loops in QCD

NASA Astrophysics Data System (ADS)

Czakon, M.; Mitov, A.; Moch, S.

2008-07-01

We present the two-loop virtual QCD corrections to the production of heavy quarks in gluon fusion. The results are exact in the limit when all kinematical invariants are large compared to the mass of the heavy quark up to terms suppressed by powers of the heavy-quark mass. Our derivation uses a simple relation between massless and massive QCD scattering amplitudes as well as a direct calculation of the massive amplitude at two loops. The results presented here together with those obtained previously for quark-quark scattering form important parts of the next-to-next-to-leading order QCD corrections to heavy-quark production in hadron-hadron collisions.

Treatment of acute massive pulmonary embolism by streptokinase during labour and delivery.

PubMed

Hall, R J; Young, C; Sutton, G C; Cambell, S

1972-12-16

A 29-year-old woman sustained an acute massive pulmonary embolism in the 32nd week of pregnancy. Rapid clinical improvement followed the use of streptokinase. Treatment was continued for 41 hours, including labour and the first three hours after delivery. There was slow but severe postpartum haemorrhage. Partial uterine atony occurred, and may have been due, at least in part, to fibrin degradation products arising from thrombolysis. No adverse effects were noted in the baby.Our experience suggests that streptokinase may be given during labour but that an oxytocic agent may be needed; and that reversal of fibrinolysis before delivery is best achieved by the use of aprotinin (Trasylol) rather than aminocaproic acid.

Lithofacies of Spencer Formation, western Tualatin Valley, Oregon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Atta, R.O.

The Spencer Formation crops out in a narrow band that trends north-northwest on the western edge of the Willamette and Tualatin Valleys, Oregon. It apparently conformably overlies mud rocks of either the Yamhill or the Nestucca Formation and is conformably overlain by the Pittsburgh Bluff Formation. The Spencer Formation consists of two members (informal): a lower highly micaceous sandstone (800-1000 ft) and an upper member that is micaceous siltstone and mudstone (1000-1300 ft). The lower member includes an upper part that is light-gray to creamy-gray, silty to muddy, pebbly lithic arkose to feldspathic litharenite, with minor arkose. Sorting is poormore » and beds may be laminated to ripple cross-laminated or massive and bioturbated with abundant mollusk shells, carbonized wood, and burrows. The lower part of the lower member is medium-gray to greenish-gray, silty, pumiceous lithic arkose to feldspathic litharenite. The texture tends to be more uniform and better sorted than that of the upper part of the member. Bedding is commonly massive due to bioturbation. The upper member is medium to dark-gray mudstone with thin pebble-conglomerate lenses. It intertongues with the lower member. Bioturbation, burrows, and carbonized wood are common. The trend in depositional environments appears to be from outer to mid-neritic (lower part, lower member) to shallow neritic, nearshore, and lagoonal (upper part, lower member, and upper member). The provenance of the Spencer Formation includes both proximal volcanics and distant plutonic and high-grade metamorphics.« less

An Overdensity of Massive, Dusty Starbursts Associated with the High-Redshift Radio Galaxy MRC1138-262 at z = 2.16

NASA Astrophysics Data System (ADS)

Altieri, Bruno; Dannerbauer, Helmut

We present Herschel and APEX LABOCA 870 μm imaging of the field of the high-redshift radio galaxy MRC1138 at z = 2.16. We detect 16 submillimeter galaxies in this ˜140 arcmin2 large bolometer map, with flux densities in the range 3-11 mJy. The pure number counts indicate an overdensity of SMGs by a factor of five compared to blank field surveys. Based on an exquisite multi-wavelength database including VLA 1.4 GHz radio and infrared observations, we verifiy whether these sources are members of the proto-cluster structure at z = 2.2 or not. Based on Herschel PACS+ SPIRE and Spitzer MIPS photometry, we derived reliable far-infrared photometric redshifts for all of our sources. VLT-ISAAC near-infrared spectroscopic observations confirmed redshifts of z ≈ 2.2 for four of these SMGs. We conclude that in total at least seven sources are part of this proto-cluster at z = 2.16. We measure a star formation rate density S FRD ˜ 1500 M⊙ yr-1 Mpc-3, four magntiudes higher compared to the global SFRD at this redshift. Striklingly, these seven sources are concentrated within a region of 2 Mpc (the typical size of clusters in the local universe) and are not distributed in the filaments as predicted by theories and traced by the Hα emitters at z ≈ 2.2. This concentration of massive, dusty starbursts is not centered on the radio galaxy which is submm bright. A significant fraction, six out of 11 SMGs with z ≈ 2.2 Hα imaging coverage are associated with Hα emitters, demonstrating the potential of tracing SMG counterparts with this source population. Our results demonstrate that indeed submm observations enable us to reveal clusters of massive, dusty starbursts and will pave the road for systematic and detailed investigations with this technique in the future.

THE PHYSICAL ENVIRONMENT AROUND IRAS 17599–2148: INFRARED DARK CLOUD AND BIPOLAR NEBULA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dewangan, L. K.; Janardhan, P.; Ojha, D. K.

We present a multiscale and multiwavelength study to investigate the star formation process around IRAS 17599–2148, which is part of an elongated filamentary structure (EFS) (extension ∼21 pc) seen in the Herschel maps. Using the Herschel data analysis, at least six massive clumps (M {sub clump} ∼ 777–7024 M {sub ⊙}) are found in the EFS with a range of temperature and column density of ∼16–39 K and ∼(0.6–11) × 10{sup 22} cm{sup −2} (A {sub V}  ∼ 7–117 mag), respectively. The EFS hosts cold gas regions (i.e., infrared dark cloud) without any radio detection and a bipolar nebula (BN) linked with the Hmore » ii region IRAS 17599–2148, tracing two distinct environments inferred through the temperature distribution and ionized emission. Based on virial analysis and higher values of self-gravitating pressure, the clumps are found unstable against gravitational collapse. We find 474 young stellar objects (YSOs) in the selected region, and ∼72% of these YSOs are found in the clusters distributed mainly toward the clumps in the EFS. These YSOs might have spontaneously formed due to processes not related to the expanding H ii region. At the edges of BN, four additional clumps are also associated with YSO clusters, which appear to be influenced by the expanding H ii region. The most massive clump in the EFS contains two compact radio sources traced in the Giant Metre-wave Radio Telescope 1.28 GHz map and a massive protostar candidate, IRS 1, prior to an ultracompact H ii phase. Using the Very Large Telescope/NACO near-infrared images, IRS 1 is resolved with a jet-like feature within a 4200 au scale.« less

Satellite accretion on to massive galaxies with central black holes

NASA Astrophysics Data System (ADS)

Boylan-Kolchin, Michael; Ma, Chung-Pei

2007-02-01

Minor mergers of galaxies are expected to be common in a hierarchical cosmology such as Λ cold dark matter. Though less disruptive than major mergers, minor mergers are more frequent and thus have the potential to affect galactic structure significantly. In this paper, we dissect the case-by-case outcome from a set of numerical simulations of a single satellite elliptical galaxy accreting on to a massive elliptical galaxy. We take care to explore cosmologically relevant orbital parameters and to set up realistic initial galaxy models that include all three relevant dynamical components: dark matter haloes, stellar bulges, and central massive black holes (BHs). The effects of several different parameters are considered, including orbital energy and angular momentum, satellite density and inner density profile, satellite-to-host mass ratio, and presence of a BH at the centre of the host. BHs play a crucial role in protecting the shallow stellar cores of the hosts, as satellites merging on to a host with a central BH are more strongly disrupted than those merging on to hosts without BHs. Orbital parameters play an important role in determining the degree of disruption: satellites on less-bound or more-eccentric orbits are more easily destroyed than those on more-bound or more-circular orbits as a result of an increased number of pericentric passages and greater cumulative effects of gravitational shocking and tidal stripping. In addition, satellites with densities typical of faint elliptical galaxies are disrupted relatively easily, while denser satellites can survive much better in the tidal field of the host. Over the range of parameters explored, we find that the accretion of a single satellite elliptical galaxy can result in a broad variety of changes, in both signs, in the surface brightness profile and colour of the central part of an elliptical galaxy. Our results show that detailed properties of the stellar components of merging satellites can strongly affect the properties of the remnants.

Towards a Unified View of Inhomogeneous Stellar Winds in Isolated Supergiant Stars and Supergiant High Mass X-Ray Binaries

NASA Astrophysics Data System (ADS)

Martínez-Núñez, Silvia; Kretschmar, Peter; Bozzo, Enrico; Oskinova, Lidia M.; Puls, Joachim; Sidoli, Lara; Sundqvist, Jon Olof; Blay, Pere; Falanga, Maurizio; Fürst, Felix; Gímenez-García, Angel; Kreykenbohm, Ingo; Kühnel, Matthias; Sander, Andreas; Torrejón, José Miguel; Wilms, Jörn

2017-10-01

Massive stars, at least ˜10 times more massive than the Sun, have two key properties that make them the main drivers of evolution of star clusters, galaxies, and the Universe as a whole. On the one hand, the outer layers of massive stars are so hot that they produce most of the ionizing ultraviolet radiation of galaxies; in fact, the first massive stars helped to re-ionize the Universe after its Dark Ages. Another important property of massive stars are the strong stellar winds and outflows they produce. This mass loss, and finally the explosion of a massive star as a supernova or a gamma-ray burst, provide a significant input of mechanical and radiative energy into the interstellar space. These two properties together make massive stars one of the most important cosmic engines: they trigger the star formation and enrich the interstellar medium with heavy elements, that ultimately leads to formation of Earth-like rocky planets and the development of complex life. The study of massive star winds is thus a truly multidisciplinary field and has a wide impact on different areas of astronomy. In recent years observational and theoretical evidences have been growing that these winds are not smooth and homogeneous as previously assumed, but rather populated by dense "clumps". The presence of these structures dramatically affects the mass loss rates derived from the study of stellar winds. Clump properties in isolated stars are nowadays inferred mostly through indirect methods (i.e., spectroscopic observations of line profiles in various wavelength regimes, and their analysis based on tailored, inhomogeneous wind models). The limited characterization of the clump physical properties (mass, size) obtained so far have led to large uncertainties in the mass loss rates from massive stars. Such uncertainties limit our understanding of the role of massive star winds in galactic and cosmic evolution. Supergiant high mass X-ray binaries (SgXBs) are among the brightest X-ray sources in the sky. A large number of them consist of a neutron star accreting from the wind of a massive companion and producing a powerful X-ray source. The characteristics of the stellar wind together with the complex interactions between the compact object and the donor star determine the observed X-ray output from all these systems. Consequently, the use of SgXBs for studies of massive stars is only possible when the physics of the stellar winds, the compact objects, and accretion mechanisms are combined together and confronted with observations. This detailed review summarises the current knowledge on the theory and observations of winds from massive stars, as well as on observations and accretion processes in wind-fed high mass X-ray binaries. The aim is to combine in the near future all available theoretical diagnostics and observational measurements to achieve a unified picture of massive star winds in isolated objects and in binary systems.

Irradiated interfaces in the Ara OB1, Carina, Eagle Nebula, and Cyg OB2 massive star formation regions

DOE PAGES

Hartigan, P.; Palmer, J.; Cleeves, L. I.

2012-09-05

Regions of massive star formation offer some of the best and most easily-observed examples of radiation hydrodynamics. Boundaries where fully-ionized H II regions transition to neutral/molecular photodissociation regions (PDRs) are of particular interest because marked temperature and density contrasts across the boundaries lead to evaporative flows and fluid dynamical instabilities that can evolve into spectacular pillar-like structures. Furthermore, when detached from their parent clouds, pillars become ionized globules that often harbor one or more young stars. H2 molecules at the interface between a PDR and an H II region absorb ultraviolet light from massive stars, and the resulting fluoresced infraredmore » emission lines are an ideal way to trace this boundary independent of obscuring dust. This paper presents H2 images of four regions of massive star formation that illustrate different types of PDR boundaries. The Ara OB1 star formation region contains a striking long wall that has several wavy structures which are present in H2, but the emission is not particularly bright because the ambient UV fluxes are relatively low. In contrast, the Carina star formation region shows strong H2 fluorescence both along curved walls and at the edges of spectacular pillars that in some cases have become detached from their parent clouds. The less-spectacular but more well-known Eagle Nebula has two regions that have strong fluorescence in addition to its pillars. And while somewhat older than the other regions, Cyg OB2 has the highest number of massive stars of the regions surveyed and contains many isolated, fluoresced globules that have head–tail morphologies which point towards the sources of ionizing radiation. Our images provide a collection of potential astrophysical analogs that may relate to ablated interfaces observed in laser experiments of radiation hydrodynamics.« less

Isolated Subscapularis Repair in Irreparable Posterosuperior Massive Rotator Cuff Tears Involving the Subscapularis Tendon.

PubMed

Kim, Sung-Jae; Choi, Yun-Rak; Jung, Min; Lee, Won-Yong; Chun, Yong-Min

2017-05-01

No previous study has examined whether isolated subscapularis tendon repair in irreparable posterosuperior massive rotator tears involving the subscapularis tendon in relatively young patients without arthritis can yield satisfactory outcomes. We hypothesized that this procedure would produce favorable outcomes in patients who might otherwise be candidates for reverse arthroplasty. Case series; Level of evidence, 4. This retrospective study included 24 patients in their 50s and 60s, without shoulder arthritis, who underwent arthroscopic isolated subscapularis repair for an irreparable massive rotator cuff tear involving the subscapularis tendon. Preoperative and postoperative visual analog scale (VAS) pain scores, subjective shoulder values (SSVs), University of California at Los Angeles (UCLA) shoulder scores, American Shoulder and Elbow Surgeons (ASES) scores, subscapularis strength (modified bell-press test; maximum of 5), and shoulder active range of motion (ROM) were assessed. Postoperative magnetic resonance arthrography (MRA) was performed 6 months postoperatively to assess structural integrity of the repaired subscapularis. At a mean 34.8 months (range, 24-49 months) of follow-up, VAS pain scores (improved from 7.1 to 2.5), SSVs (33.3 to 75.2), ASES scores (35.9 to 76.0), UCLA shoulder scores (11.6 to 24.8), subscapularis strength, and ROM were significantly improved compared with preoperative measurements ( P < .001). Subscapularis muscle strength improved from 3.7 to 4.2 ( P < .001). For active ROM, forward flexion and internal rotation improved significantly ( P < .001); however, external rotation exhibited no significant improvement. Follow-up MRA was performed in 22 patients (92%) and showed retear of the repaired subscapularis in 6 (27% of the 22). Isolated repair of the subscapularis tendon in irreparable massive rotator cuff tears involving the subscapularis tendon yielded satisfactory short-term outcomes and structural integrity in patients in their 50s and 60s without arthritis. If patients with irreparable massive rotator cuff tears involving the subscapularis tendon are relatively young or have minimal concomitant arthritis, this repair can be worthwhile.

ALMA view of the massive dense clump in the Galactic center 50 km s-1 molecular cloud .

NASA Astrophysics Data System (ADS)

Uehara, K.; Tsuboi, M.; Kitamura, Y.; Miyawaki, R.; Miyazaki, A.

We observed the 50 km s-1 molecular cloud with a high angular resolution (˜1.5 arcsec) using ALMA in the H13CO+ J=1-0, C34S J=2-1, CS J=2-1 and SiO v=0 J=2-1 emission lines. This cloud is a candidate for the massive star forming region induced by cloud-cloud collision (CCC). We newly found a massive dense clump (DC1) with a size of ˜0.3 pc in the CCC region of the cloud in the H13CO+ J=1-0 map. The DC1 seems to be located on a line where the four HII regions line up. Furthermore, the DC1 has a broad velocity width covering ˜30 km s-1 and ˜60 km s-1 components in the CS J=2-1 map; the 30 km s-1 component has filamentary structures and the 60 km s-1 one a sheet-like structure. From the position-velocity diagrams of the H13CO+ J=1-0 and CS J=2-1 lines and the intensity ratio of T(SiO v=0 J=2-1)/T(H13CO+ J=1-0), i.e., a shock tracer, we consider that the DC1 has formed by the CCC between the filaments and the sheet-like gas. The LTE mass and virial parameter of the DC1 is estimated to be ˜1.3×104 M_ȯ and ˜5, respectively. These facts suggest that the DC1 is likely in a gravitationally bound state and may start massive star formation. We propose a scenario that the CCC induced the massive star formation in the HII region A ˜105 years ago and now causes the formation and collapse of the DC1; the clump would evolve to an HII region within ˜105 years.

USA: Economics, Politics, Ideology, Number 12, December 1977

DTIC Science & Technology

1978-01-19

which will guarantee the pioneer firm the neces- sary profit level. The structure of market prices, however, represents a poor reflection, as we...the timely and rapid rearrangement of structural proportions. The economic mechanism of state-monopolistic capitalism, however, was incapable of...ensuring the necessary dynamism in the large-scale economy. The development of massive structural changes in the American economy is a complex and

Computational methods and software systems for dynamics and control of large space structures

NASA Technical Reports Server (NTRS)

Park, K. C.; Felippa, C. A.; Farhat, C.; Pramono, E.

1990-01-01

Two key areas of crucial importance to the computer-based simulation of large space structures are discussed. The first area involves multibody dynamics (MBD) of flexible space structures, with applications directed to deployment, construction, and maneuvering. The second area deals with advanced software systems, with emphasis on parallel processing. The latest research thrust in the second area involves massively parallel computers.

Applying Massively Parallel Kinetic Monte Carlo Methods to Simulate Grain Growth and Sintering in Powdered Metals

DTIC Science & Technology

2011-09-01

Structure Evolution During Sintering From [19]. ...................................20 Figure 10. Ising Model Configuration With Eight Nearest Neighbors...INTRODUCTION A. MOTIVATION The ability to fabricate structural components from metals with a fine (micron- sized), controlled grain size is one of the...hallmarks of modern, structural metallurgy. Powder metallurgy, in particular, consists of powder manufacture, powder blending, compacting, and sintering

Lifelong Learning in the European Union: Whither the Lisbon Strategy?

ERIC Educational Resources Information Center

Jones, Hywel Ceri

2005-01-01

This article traces the Lisbon strategy back to the White Paper issued by President Jacques Delors in 1993 on "Growth, Competitiveness, and Jobs" as the launching point for the structural reform agenda needed to turn around the massive unemployment crisis and proposing a combination of policies for the structural reform of the labour…

Management of Major Vascular Injury: Open.

PubMed

Tisherman, Samuel A

2016-06-01

Major blood vessels are in proximity to other vital structures in the neck and base of skull. Infections and tumors of the head and neck can invade vascular structures. Vascular injuries can lead to massive hemorrhage, cerebral ischemia, or stroke. Emergency and definitive management can be challenging. Copyright © 2016 Elsevier Inc. All rights reserved.

Ocean Drilling Program Leg 178 (Antarctic Peninsula): Sedimentology of glacially influenced continental margin topsets and foresets

USGS Publications Warehouse

Eyles, N.; Daniels, J.; Osterman, L.E.; Januszczak, N.

2001-01-01

Ocean Drilling Program Leg 178 (February-April 1998) drilled two sites (Sites 1097 and 1103) on the outer Antarctic Peninsula Pacific continental shelf. Recovered strata are no older than late Miocene or early Pliocene (<4.6 Ma). Recovery at shallow depths in loosely consolidated and iceberg-turbated bouldery sediment was poor but improved with increasing depth and consolidation to allow description of lithofacies and biofacies and interpretation of depositional environment. Site 1097 lies on the outer shelf within Marguerite Trough which is a major outlet for ice expanding seaward from the Antarctic Peninsula and reached a maximum depth drilled of 436.6 m below the sea floor (mbsf). Seismic stratigraphic data show flat-lying upper strata resting on strata that dip gently seaward. Uppermost strata, to a depth of 150 mbsf, were poorly recovered, but data suggest they consist of diamictites containing reworked and abraded marine microfauna. This interval is interpreted as having been deposited largely as till produced by subglacial cannibalization of marine sediments (deformation till) recording ice sheet expansion across the shelf. Underlying gently dipping strata show massive, stratified and graded diamictite facies with common bioturbation and slump stuctures that are interbedded with laminated and massive mudstones with dropstones. The succession contains a well-preserved in situ marine microfauna typical of open marine and proglacial marine environments. The lower gently dipping succession at Site 1097 is interpreted as a complex of sediment gravity flows formed of poorly sorted glacial debris. Site 1103 was drilled in that part of the continental margin that shows uppermost flat-lying continental shelf topsets overlying steeper dipping slope foresets seaward of a structural mid-shelf high. Drilling reached a depth of 363 mbsf with good recovery in steeply dipping continental slope foreset strata. Foreset strata are dominated by massive and chaotically stratified diamictites interbedded with massive and graded sandstones and mudstones. The sedimentary record and seismic stratigraphy is consistent with deposition on a continental slope from debris flows and turbidity currents released from a glacial source. Data from Sites 1097 and 1103 suggest the importance of aggradation of the Antarctic Peninsula continental shelf by tilt deposition and progradation of the slope by mass flow. This may provide a model for the interpretation of Palaeozoic and Proterozoic glacial successions that accumulated on glacially influenced continental margins.

Star formation induced by cloud-cloud collisions and galactic giant molecular cloud evolution

NASA Astrophysics Data System (ADS)

Kobayashi, Masato I. N.; Kobayashi, Hiroshi; Inutsuka, Shu-ichiro; Fukui, Yasuo

2018-05-01

Recent millimeter/submillimeter observations towards nearby galaxies have started to map the whole disk and to identify giant molecular clouds (GMCs) even in the regions between galactic spiral structures. Observed variations of GMC mass functions in different galactic environments indicates that massive GMCs preferentially reside along galactic spiral structures whereas inter-arm regions have many small GMCs. Based on the phase transition dynamics from magnetized warm neutral medium to molecular clouds, Kobayashi et al. (2017, ApJ, 836, 175) proposes a semi-analytical evolutionary description for GMC mass functions including a cloud-cloud collision (CCC) process. Their results show that CCC is less dominant in shaping the mass function of GMCs than the accretion of dense H I gas driven by the propagation of supersonic shock waves. However, their formulation does not take into account the possible enhancement of star formation by CCC. Millimeter/submillimeter observations within the Milky Way indicate the importance of CCC in the formation of star clusters and massive stars. In this article, we reformulate the time-evolution equation largely modified from Kobayashi et al. (2017, ApJ, 836, 175) so that we additionally compute star formation subsequently taking place in CCC clouds. Our results suggest that, although CCC events between smaller clouds are more frequent than the ones between massive GMCs, CCC-driven star formation is mostly driven by massive GMCs ≳ 10^{5.5} M_{⊙} (where M⊙ is the solar mass). The resultant cumulative CCC-driven star formation may amount to a few 10 percent of the total star formation in the Milky Way and nearby galaxies.

The last 6 Gyr of dark matter assembly in massive galaxies from the Kilo Degree Survey

NASA Astrophysics Data System (ADS)

Tortora, C.; Napolitano, N. R.; Roy, N.; Radovich, M.; Getman, F.; Koopmans, L. V. E.; Verdoes Kleijn, G. A.; Kuijken, K. H.

2018-01-01

We study the dark matter (DM) assembly in the central regions of massive early-type galaxies up to z ∼ 0.65. We use a sample of ∼3800 massive (log M⋆/M⊙ > 11.2) galaxies with photometry and structural parameters from 156 deg2 of the Kilo Degree Survey (KiDS), and spectroscopic redshifts and velocity dispersions from Sloan Digital Sky Survey (SDSS). We obtain central total-to-stellar mass ratios, Mdyn/M⋆, and DM fractions, by determining dynamical masses, Mdyn, from Jeans modelling of SDSS aperture velocity dispersions and stellar masses, M⋆, from KiDS galaxy colours. We first show how the central DM fraction correlates with structural parameters, mass and density proxies, and demonstrate that most of the local correlations are still observed up to z ∼ 0.65; at fixed M⋆, local galaxies have larger DM fraction, on average, than their counterparts at larger redshift. We also interpret these trends with a non-universal initial mass function (IMF), finding a strong evolution with redshift, which contrast independent observations and is at odds with the effect of galaxy mergers. For a fixed IMF, the galaxy assembly can be explained, realistically, by mass and size accretion, which can be physically achieved by a series of minor mergers. We reproduce both the Re-M⋆ and Mdyn/M⋆-M⋆ evolution with stellar and dark mass changing at a different rate. This result suggests that the main progenitor galaxy is merging with less massive systems, characterized by a smaller Mdyn/M⋆, consistently with results from halo abundance matching.

Post-depositional tectonic modification of VMS deposits in Iberia and its economic significance

NASA Astrophysics Data System (ADS)

Castroviejo, Ricardo; Quesada, Cecilio; Soler, Miguel

2011-07-01

The original stratigraphic relationships and structure of VMS deposits are commonly obscured by deformation. This can also affect their economic significance, as shown by several Iberian Pyrite Belt (IPB, SW Iberia) examples. The contrasting rheologic properties of the different lithologies present in an orebody (massive sulphide, feeder stockwork, alteration envelope, volcanic and sedimentary rocks) play a major role in determining its overall behaviour. Variscan thin-skinned tectonics led to stacking of the massive pyrite and stockwork bodies in duplex structures, resulting in local thickening and increased tonnage of minable mineralization. Furthermore, differential mechanical behaviour of the different sulphide minerals localised the detachments along relatively ductile sulphide-rich bands. The result was a geochemical and mineralogical reorganisation of most deposits, which now consist of barren, massive pyrite horses, bounded by base metal-rich ductile shear zones. Metal redistribution was enhanced by mobilisation of the base metal sulphides from the initially impoverished massive pyrite, through pressure-solution processes, to tensional fissures within the already ductile shear zones. In NW Iberia, VMS deposits were also strongly overprinted by the Variscan deformation during emplacement of the Cabo Ortegal and Órdenes allochthonous nappe complexes, but no stacking of the orebodies was produced. Original contacts were transposed, and the orebodies, their feeder zones and the country rock acquired pronounced laminar geometry. In lower-grade rocks (greenschist facies, Cabo Ortegal Complex), solution transfer mechanisms are common in pyrite, which remains in the brittle domain, while chalcopyrite shows ductile behaviour. In higher-grade rocks (amphibolite facies, Órdenes Complex), metamorphic recrystallisation overprints earlier deformation textures. The contrasting behaviour of the IPB and NW Iberian deposits is explained by key factors that affect their final geometry, composition and economics, such as pre-deformation structure, size and mineralogical composition of the orebody and associated lithologies, temperature, crustal level, deviatoric stress and availability of a fluid phase during deformation and the style and rate of deformation.

THE DARKEST SHADOWS: DEEP MID-INFRARED EXTINCTION MAPPING OF A MASSIVE PROTOCLUSTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butler, Michael J.; Tan, Jonathan C.; Kainulainen, Jouni

We use deep 8 μm Spitzer-IRAC imaging of massive Infrared Dark Cloud (IRDC) G028.37+00.07 to construct a mid-infrared (MIR) extinction map that probes mass surface densities up to Σ ∼ 1 g cm{sup –2} (A{sub V} ∼ 200 mag), amongst the highest values yet probed by extinction mapping. Merging with an NIR extinction map of the region creates a high dynamic range map that reveals structures down to A{sub V} ∼ 1 mag. We utilize the map to: (1) measure a cloud mass ∼7 × 10{sup 4} M {sub ☉} within a radius of ∼8 pc. {sup 13}CO kinematics indicate thatmore » the cloud is gravitationally bound. It thus has the potential to form one of the most massive young star clusters known in the Galaxy. (2) Characterize the structures of 16 massive cores within the IRDC, finding they can be fit by singular polytropic spheres with ρ∝r{sup −k{sub ρ}} and k {sub ρ} = 1.3 ± 0.3. They have Σ-bar ≃0.1--0.4 g cm{sup −2}—relatively low values that, along with their measured cold temperatures, suggest that magnetic fields, rather than accretion-powered radiative heating, are important for controlling fragmentation of these cores. (3) Determine the Σ (equivalently column density or A{sub V} ) probability distribution function (PDF) for a region that is nearly complete for A{sub V} > 3 mag. The PDF is well fit by a single log-normal with mean A-bar {sub V}≃9 mag, high compared to other known clouds. It does not exhibit a separate high-end power law tail, which has been claimed to indicate the importance of self-gravity. However, we suggest that the PDF does result from a self-similar, self-gravitating hierarchy of structures present over a wide range of scales in the cloud.« less

Cardiopulmonary Exercise Testing in Patients Following Massive and Submassive Pulmonary Embolism.

PubMed

Albaghdadi, Mazen S; Dudzinski, David M; Giordano, Nicholas; Kabrhel, Christopher; Ghoshhajra, Brian; Jaff, Michael R; Weinberg, Ido; Baggish, Aaron

2018-03-03

Little data exist regarding the functional capacity of patients following acute pulmonary embolism. We sought to characterize the natural history of symptom burden, right ventricular (RV) structure and function, and exercise capacity among survivors of massive and submassive pulmonary embolism. Survivors of submassive or massive pulmonary embolism (n=20, age 57±13.3 years, 8/20 female) underwent clinical evaluation, transthoracic echocardiography, and cardiopulmonary exercise testing at 1 and 6 months following hospital discharge. At 1 month, 9/20 (45%) patients had New York Heart Association II or greater symptoms, 13/20 (65%) demonstrated either persistent RV dilation or systolic dysfunction, and 14/20 (70%) had objective exercise impairment as defined by a peak oxygen consumption (V˙O 2 ) of <80% of age-sex predicted maximal values (16.25 [13.4-20.98] mL/kg per minute). At 6 months, no appreciable improvements in symptom severity, RV structure or function, and peak V˙O 2 (17.45 [14.08-22.48] mL/kg per minute, P =NS) were observed. No patients demonstrated an exercise limitation attributable to either RV/pulmonary vascular coupling, as defined by a VE/VCO 2 slope >33, or a pulmonary mechanical limit to exercise at either time point. Similarly, persistent RV dilation or dysfunction was not significantly related to symptom burden or peak V˙O 2 at either time point. Persistent symptoms, abnormalities of RV structure and function, and objective exercise limitation are common among survivors of massive and submassive pulmonary embolism. Functional impairment appears to be attributable to general deconditioning rather than intrinsic cardiopulmonary limitation, suggesting an important role for prescribed exercise rehabilitation as a means toward improved patient outcomes and quality of life. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Temporal and taxonomic contrasts in coral growth at Davies Reef, central Great Barrier Reef, Australia

NASA Astrophysics Data System (ADS)

Anderson, Kristen D.; Cantin, Neal E.; Heron, Scott F.; Lough, Janice M.; Pratchett, Morgan S.

2018-06-01

Demographic processes, such as growth, can have an important influence on the population and community structure of reef-building corals. Importantly, ongoing changes in environmental conditions (e.g. ocean warming) are expected to affect coral growth, contributing to changes in the structure of coral populations and communities. This study quantified contemporary growth rates (linear extension and calcification) for the staghorn coral, Acropora muricata, at Davies Reef, central Great Barrier Reef, Australia. Growth rates were measured at three different depths (5, 10, and 15 m) over 2 yr (2012-2014) assessing both seasonal and inter-annual variability. Results of this study were compared to equivalent measurements made in 1980-1982 at the same location. To assist in understanding inter-annual variability in coral growth, we also examined annual growth bands from massive Porites providing continuous growth and records of flooding history for Davies Reef over the period 1979-2012. Linear extension rates of A. muricata were substantially (11-62%) lower in 2012-2014 compared to 1980-1982, especially at 10 and 15 m depths. These declines in growth coincide with a + 0.14 °C change in annual mean temperature. For massive Porites, however, calcification rates were highly variable among years and there was no discernible long-term change in growth despite sustained increases in temperature of 0.064 °C per decade. Apparent differences in the growth rates of Acropora between 1980-1982 and 2012-2014 may reflect inter-annual variation in coral growth (as seen for massive Porites), though it is known branching Acropora is much more sensitive to changing environmental conditions than massive corals. There are persistent issues in assessing the sensitivities of branching corals to environmental change due to limited capacity for retrospective analyses of growth, but given their disproportionate contribution to habitat complexity and reef structure, it is critical to ascertain whether there are increasing impacts on their demography.

Geochemical studies of rare earth elements in the Portuguese pyrite belt, and geologic and geochemical controls on gold distribution

USGS Publications Warehouse

Grimes, David J.; Earhart, Robert L.; de Carvalho, Delfim; Oliveira, Vitor; Oliveira, Jose T.; Castro, Paulo

1998-01-01

This report describes geochemical and geological studies which were conducted by the U.S. Geological Survey (USGS) and the Servicos Geologicos de Portugal (SPG) in the Portuguese pyrite belt (PPB) in southern Portugal. The studies included rare earth element (REE) distributions and geological and geochemical controls on the distribution of gold. Rare earth element distributions were determined in representative samples of the volcanic rocks from five west-trending sub-belts of the PPB in order to test the usefulness of REE as a tool for the correlation of volcanic events, and to determine their mobility and application as hydrothermal tracers. REE distributions in felsic volcanic rocks show increases in the relative abundances of heavy REE and a decrease in La/Yb ratios from north to south in the Portuguese pyrite belt. Anomalous amounts of gold are distributed in and near massive and disseminated sulfide deposits in the PPB. Gold is closely associated with copper in the middle and lower parts of the deposits. Weakly anomalous concentrations of gold were noted in exhalative sedimentary rocks that are stratigraphically above massive sulfide deposits in a distal manganiferous facies, whereas anomalously low concentrations were detected in the barite-rich, proximal-facies exhalites. Altered and pyritic felsic volcanic rocks locally contain highly anomalous concentrations of gold, suggesting that disseminated sulfide deposits and the non-ore parts of massive sulfide deposits should be evaluated for their gold potential.

Structure of the germline genome of Tetrahymena thermophila and relationship to the massively rearranged somatic genome

PubMed Central

Hamilton, Eileen P; Kapusta, Aurélie; Huvos, Piroska E; Bidwell, Shelby L; Zafar, Nikhat; Tang, Haibao; Hadjithomas, Michalis; Krishnakumar, Vivek; Badger, Jonathan H; Caler, Elisabet V; Russ, Carsten; Zeng, Qiandong; Fan, Lin; Levin, Joshua Z; Shea, Terrance; Young, Sarah K; Hegarty, Ryan; Daza, Riza; Gujja, Sharvari; Wortman, Jennifer R; Birren, Bruce W; Nusbaum, Chad; Thomas, Jainy; Carey, Clayton M; Pritham, Ellen J; Feschotte, Cédric; Noto, Tomoko; Mochizuki, Kazufumi; Papazyan, Romeo; Taverna, Sean D; Dear, Paul H; Cassidy-Hanley, Donna M; Xiong, Jie; Miao, Wei; Orias, Eduardo; Coyne, Robert S

2016-01-01

The germline genome of the binucleated ciliate Tetrahymena thermophila undergoes programmed chromosome breakage and massive DNA elimination to generate the somatic genome. Here, we present a complete sequence assembly of the germline genome and analyze multiple features of its structure and its relationship to the somatic genome, shedding light on the mechanisms of genome rearrangement as well as the evolutionary history of this remarkable germline/soma differentiation. Our results strengthen the notion that a complex, dynamic, and ongoing interplay between mobile DNA elements and the host genome have shaped Tetrahymena chromosome structure, locally and globally. Non-standard outcomes of rearrangement events, including the generation of short-lived somatic chromosomes and excision of DNA interrupting protein-coding regions, may represent novel forms of developmental gene regulation. We also compare Tetrahymena’s germline/soma differentiation to that of other characterized ciliates, illustrating the wide diversity of adaptations that have occurred within this phylum. DOI: http://dx.doi.org/10.7554/eLife.19090.001 PMID:27892853

NASP and ISPA Response to the Japanese Natural Disaster

ERIC Educational Resources Information Center

Pfohl, Bill; Cowan, Katherine

2011-01-01

The authors have worked together with the NASP (National Association of School Psychologists) National Emergency Assistance Team (NEAT) for a decade to help coordinate communications around large-scale crisis response efforts. The massive earthquake and tsunami that devastated the northeastern part of Japan and the subsequent response represented…

[Strongyloidosis. Part IX. Treatment].

PubMed

Soroczan, Wiesław

2002-01-01

The treatment of chronic and massive (uncomplicated) and severe (complicated) disseminated strongyloidosis, was presented from the historical point of view. The sequence of achievements in regard of treatment of the gentian violet, dithiazine iodide, benzimidazoles (thiabendazole, mebendazole, albendazole, cambendazole), ivermectin and cyclosporin A, was described. The recommendations for treatment of strongyloidosis are also given.

Designing Effective MOOCs

ERIC Educational Resources Information Center

Conole, Gráinne

2015-01-01

Massive open online courses (MOOCs) have expanded significantly in recent years and are challenging traditional educational fee-paying offerings. The advantages of MOOCs are cited as the fact that they are free, that they enable participants to be part of a global community of peers and to have the experience of learning through social media and…

More than a Little Red Schoolhouse.

ERIC Educational Resources Information Center

American School and University, 1982

1982-01-01

The new fine arts complex at Memphis State University (Tennessee) has extensive south-facing windows and massive Trombe walls, composed of concrete blocks that absorb heat and release it slowly, that together provide about 20 percent of the building's heat. Part of the masonry was also designed to absorb sound. (Author/MLF)

Collective Information Literacy in Massively Multiplayer Online Games

ERIC Educational Resources Information Center

Martin, Crystle; Steinkuehler, Constance

2010-01-01

This article explores the forms of information literacy that arise in commercial entertainment games like "World of Warcraft." Using examples culled from eight months of online ethnographic data, the authors detail the forms of information literacy that arise as a regular part of in-game social interaction, emphasizing (ironically) the…

Money, Policy Tangled in Wisconsin Labor Feud

ERIC Educational Resources Information Center

Cavanagh, Sean

2011-01-01

Gov. Scott Walker's sweeping proposal to scale back collective bargaining rights for most public employees in Wisconsin has sparked a rancorous standoff with teachers across the state--and fueled speculation about whether similar plans will gain traction in other parts of the country. But as massive demonstrations played out in Madison--an…

3. NORTH ELEVATION OF THE HOT BAY, SHOWING RAILROAD TRACKS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. NORTH ELEVATION OF THE HOT BAY, SHOWING RAILROAD TRACKS LEADING TO THE MASSIVE STEEL-LINED CONCRETE ENTRANCE DOOR. PART OF THE INTRICATE HVAC SYSTEM IS WEST (RIGHT) OF THE DOOR. - Nevada Test Site, Engine Maintenance Assembly & Disassembly Facility, Area 25, Jackass Flats, Mercury, Nye County, NV

Learning for the Natural Environment: The Case against Anthropocentrism

ERIC Educational Resources Information Center

Horsthemke, Kai

2009-01-01

The world (Africa in particular) is in a progressive state of environmental crisis, caused by global warming, loss of biodiversity, human overpopulation, pollution, massive deforestation and desertification, urbanization and many other environmental problems and risk factors. For several commentators and theorists, part of the solution resides in…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Birmingham, D.; Kantowski, R.; Milton, K.A.

We use two methods of computing the unique logarithmically divergent part of the Casimir energy for massive scalar and spinor fields defined on even-dimensional Kaluza-Klein spaces of the form M/sup 4/ x S/sup N//sup 1/ x S/sup N//sup 2/ x xxx. Both methods (heat kernel and direct) give identical results. The first evaluates the required internal zeta function by identifying it in the asymptotic expansion of the trace of the heat kernel, and the second evaluates the zeta function directly using the Euler-Maclaurin sum formula. In Appendix C we tabulate these energies for all spaces of total internal dimension lessmore » than or equal to6. These methods are easily applied to vector and tensor fields needed in computing one-loop vacuum gravitational energies on these spaces. Stable solutions are given for internal structure S/sup 2/ x S/sup 2/.« less

Chandra/ACIS Observations of the 30 Doradus Star-Forming Complex

NASA Astrophysics Data System (ADS)

Townsley, Leisa; Broos, Patrick; Feigelson, Eric; Burrows, David; Chu, You-Hua; Garmire, Gordon; Griffiths, Richard; Maeda, Yoshitomo; Pavlov, George; Tsuboi, Yohko

2002-04-01

30 Doradus is the archetype giant extragalactic H II region, a massive star-forming complex in the Large Magellanic Cloud. We examine high-spatial-resolution X-ray images and spectra of the essential parts of 30 Doradus, obtained with the Advanced CCD Imaging Spectrometer (ACIS) aboard the Chandra X-ray Observatory. The central cluster of young high-mass stars, R136, is resolved at the arcsecond level, allowing spectral analysis of bright constituents; other OB/Wolf-Rayet binaries and multiple systems (e.g. R139, R140) are also detected. Spatially-resolved spectra are presented for N157B, the composite SNR containing a 16-msec pulsar. The spectrally soft superbubble structures seen by ROSAT are dramatically imaged by Chandra; we explore the spectral differences they exhibit. Taken together, the components of 30 Doradus give us an excellent microscopic view of high-energy phenomena seen on larger scales in more distant galaxies as starbursts and galactic winds.

Bayesian Analysis of the Power Spectrum of the Cosmic Microwave Background

NASA Technical Reports Server (NTRS)

Jewell, Jeffrey B.; Eriksen, H. K.; O'Dwyer, I. J.; Wandelt, B. D.

2005-01-01

There is a wealth of cosmological information encoded in the spatial power spectrum of temperature anisotropies of the cosmic microwave background. The sky, when viewed in the microwave, is very uniform, with a nearly perfect blackbody spectrum at 2.7 degrees. Very small amplitude brightness fluctuations (to one part in a million!!) trace small density perturbations in the early universe (roughly 300,000 years after the Big Bang), which later grow through gravitational instability to the large-scale structure seen in redshift surveys... In this talk, I will discuss a Bayesian formulation of this problem; discuss a Gibbs sampling approach to numerically sampling from the Bayesian posterior, and the application of this approach to the first-year data from the Wilkinson Microwave Anisotropy Probe. I will also comment on recent algorithmic developments for this approach to be tractable for the even more massive data set to be returned from the Planck satellite.

Bacterial chromosome organization and segregation

PubMed Central

Badrinarayanan, Anjana; Le, Tung BK; Laub, Michael T

2016-01-01

If fully stretched out, a typical bacterial chromosome would be nearly one millimeter long, or approximately 1000 times the length of a cell. Not only must cells massively compact their genetic material, but they must also organize their DNA in a manner that is compatible with a range of cellular processes, including DNA replication, DNA repair, homologous recombination, and horizontal gene transfer. Recent work, driven in part by technological advances, has begun to reveal the general principles of chromosome organization in bacteria. Here, drawing on studies of many different organisms, we review the emerging picture of how bacterial chromosomes are structured at multiple length-scales, highlighting the functions of various DNA-binding proteins and impact of physical forces. Additionally, we discuss the spatial dynamics of chromosomes, particularly during their segregation to daughter cells. Although there has been tremendous progress, we also highlight gaps that remain in understanding chromosome organization and segregation. PMID:26566111

Influence of geologic setting on ground-water availability in the Lawrenceville area, Gwinnett County, Georgia

USGS Publications Warehouse

Williams, Lester J.; Kath, Randy L.; Crawford, Thomas J.; Chapman, Melinda J.

2005-01-01

Obtaining large quantities of ground water needed for municipal and industrial supply in the Piedmont and Blue Ridge physiographic provinces can be challenging because of the complex geology and the typically low primary permeability of igneous and metamorphic rocks. Areas of enhanced secondary permeability in the bedrock do occur, however, and 'high-yield' wells are not uncommon, particularly where careful site-selection techniques are used prior to test drilling. The U.S. Geological Survey - in cooperation with the City of Lawrenceville, Georgia - conducted this study from 2000 to 2002 to learn more about how different geologic settings influence the availability of ground water in igneous and metamorphic bedrock with the expectation that this knowledge could be used to help identify additional water resources in the area. In compositionally layered-rock settings, wells derive water almost exclusively from lithologically and structurally controlled water-bearing zones formed parallel to foliation and compositional layering. These high-permeability, water-bearing zones - termed foliation-parallel parting systems -combined with high-angle joint systems, are the primary control for the high-yield wells drilled in the Lawrenceville area; yields range from 100 to several hundred gallons per minute (gal/min). Near Lawrenceville, areas with high ground-water yield are present in sequences of amphibolite, biotite gneiss, and button schist where the structural attitude of the rocks is gently dipping, in areas characterized by abundant jointing, and in topographic settings with a continuous source of recharge along these structures. In massive-rock settings, wells derive water mostly from joint systems, although foliation-parallel parting systems also may be important. Wells deriving water primarily from steeply-dipping joint systems typically have low yields ranging from 1 to 5 gal/min. Joint systems in massive-rock settings can be identified and characterized by using many of the methods described in this report. Geologic mapping was the primary method used to determine the distribution, variability, and relative concentrations (intensity) of joint systems. In the subsurface, joints were characterized by taking orientation measurements in the open boreholes of wells using acoustic and/or optical televiewers. In this investigation, the only practical approach found for locating areas of high ground-water potential was first through detailed geologic mapping followed by test drilling, borehole geophysical logging, and aquifer testing. Geologic methods help characterize both large- and small-scale structures and other lithologic and stratigraphic features that influence development of increased secondary permeability in the bedrock. The rock types, discontinuities, depth of weathering, topographic position, and recharge potential - which were the principal factors assessed through detailed geologic mapping - must be evaluated carefully, in relation to one another, to assess the ground-water potential in a given area.

Molecular Innovation in Ciliates with Complex Genome Rearrangements

NASA Astrophysics Data System (ADS)

Neme, R.; Landweber, L. F.

2017-07-01

We study molecular innovation in several ciliate species with unique massive genome rearrangements to understand how a radically distinct genome architecture can shape the process of acquiring new functions, genes and structures.

A hot compact dust disk around a massive young stellar object.

PubMed

Kraus, Stefan; Hofmann, Karl-Heinz; Menten, Karl M; Schertl, Dieter; Weigelt, Gerd; Wyrowski, Friedrich; Meilland, Anthony; Perraut, Karine; Petrov, Romain; Robbe-Dubois, Sylvie; Schilke, Peter; Testi, Leonardo

2010-07-15

Circumstellar disks are an essential ingredient of the formation of low-mass stars. It is unclear, however, whether the accretion-disk paradigm can also account for the formation of stars more massive than about 10 solar masses, in which strong radiation pressure might halt mass infall. Massive stars may form by stellar merging, although more recent theoretical investigations suggest that the radiative-pressure limit may be overcome by considering more complex, non-spherical infall geometries. Clear observational evidence, such as the detection of compact dusty disks around massive young stellar objects, is needed to identify unambiguously the formation mode of the most massive stars. Here we report near-infrared interferometric observations that spatially resolve the astronomical-unit-scale distribution of hot material around a high-mass ( approximately 20 solar masses) young stellar object. The image shows an elongated structure with a size of approximately 13 x 19 astronomical units, consistent with a disk seen at an inclination angle of approximately 45 degrees . Using geometric and detailed physical models, we found a radial temperature gradient in the disk, with a dust-free region less than 9.5 astronomical units from the star, qualitatively and quantitatively similar to the disks observed in low-mass star formation. Perpendicular to the disk plane we observed a molecular outflow and two bow shocks, indicating that a bipolar outflow emanates from the inner regions of the system.

Large-scale molecular dynamics simulation of DNA: implementation and validation of the AMBER98 force field in LAMMPS.

PubMed

Grindon, Christina; Harris, Sarah; Evans, Tom; Novik, Keir; Coveney, Peter; Laughton, Charles

2004-07-15

Molecular modelling played a central role in the discovery of the structure of DNA by Watson and Crick. Today, such modelling is done on computers: the more powerful these computers are, the more detailed and extensive can be the study of the dynamics of such biological macromolecules. To fully harness the power of modern massively parallel computers, however, we need to develop and deploy algorithms which can exploit the structure of such hardware. The Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) is a scalable molecular dynamics code including long-range Coulomb interactions, which has been specifically designed to function efficiently on parallel platforms. Here we describe the implementation of the AMBER98 force field in LAMMPS and its validation for molecular dynamics investigations of DNA structure and flexibility against the benchmark of results obtained with the long-established code AMBER6 (Assisted Model Building with Energy Refinement, version 6). Extended molecular dynamics simulations on the hydrated DNA dodecamer d(CTTTTGCAAAAG)(2), which has previously been the subject of extensive dynamical analysis using AMBER6, show that it is possible to obtain excellent agreement in terms of static, dynamic and thermodynamic parameters between AMBER6 and LAMMPS. In comparison with AMBER6, LAMMPS shows greatly improved scalability in massively parallel environments, opening up the possibility of efficient simulations of order-of-magnitude larger systems and/or for order-of-magnitude greater simulation times.

Rapidly rotating neutron stars with a massive scalar field—structure and universal relations

NASA Astrophysics Data System (ADS)

Doneva, Daniela D.; Yazadjiev, Stoytcho S.

2016-11-01

We construct rapidly rotating neutron star models in scalar-tensor theories with a massive scalar field. The fact that the scalar field has nonzero mass leads to very interesting results since the allowed range of values of the coupling parameters is significantly broadened. Deviations from pure general relativity can be very large for values of the parameters that are in agreement with the observations. We found that the rapid rotation can magnify the differences several times compared to the static case. The universal relations between the normalized moment of inertia and quadrupole moment are also investigated both for the slowly and rapidly rotating cases. The results show that these relations are still EOS independent up to a large extend and the deviations from pure general relativity can be large. This places the massive scalar-tensor theories amongst the few alternative theories of gravity that can be tested via the universal I-Love-Q relations.

W49A: A Massive Molecular Cloud Forming a Massive Star Cluster in the Galactic Disk

NASA Astrophysics Data System (ADS)

Galvan-Madrid, Roberto; Liu, Hauyu Baobab; Pineda, Jaime E.; Zhang, Zhi-Yu; Ginsburg, Adam; Roman-Zuñiga, Carlos; Peters, Thomas

2015-08-01

I summarize our current results of the MUSCLE survey of W49A, the most luminous star formation region in the Milky Way. Our approach emphasizes multi-scale, multi-resolution imaging in dust, ionized-, and molecular gas, to trace the multiple gas components from <0.1 pc (core scale) all the way up to the scale of the entire giant molecular cloud (GMC), ˜100 pc. The 106 M⊙ GMC is structured in a radial network of filaments that converges toward the central 'hub' with ˜2x105 M⊙, which contains within a few pc a deeply embedded young massive cluster (YMC) of stellar mass ~5x104 M⊙. We also discuss the dynamics of the filamentary network, the role of turbulence in the formation of this YMC, and how objects like W49A can link Milky Way and extragalactic star formation relations.

On stars, galaxies and black holes in massive bigravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Enander, Jonas; Mörtsell, Edvard, E-mail: enander@fysik.su.se, E-mail: edvard@fysik.su.se

In this paper we study the phenomenology of stars and galaxies in massive bigravity. We give parameter conditions for the existence of viable star solutions when the radius of the star is much smaller than the Compton wavelength of the graviton. If these parameter conditions are not met, we constrain the ratio between the coupling constants of the two metrics, in order to give viable conditions for e.g. neutron stars. For galaxies, we put constraints on both the Compton wavelength of the graviton and the conformal factor and coupling constants of the two metrics. The relationship between black holes andmore » stars, and whether the former can be formed from the latter, is discussed. We argue that the different asymptotic structure of stars and black holes makes it unlikely that black holes form from the gravitational collapse of stars in massive bigravity.« less

Massive MIMO-OFDM indoor visible light communication system downlink architecture design

NASA Astrophysics Data System (ADS)

Lang, Tian; Li, Zening; Chen, Gang

2014-10-01

Multiple-input multiple-output (MIMO) technique is now used in most new broadband communication system, and orthogonal frequency division multiplexing (OFDM) is also utilized within current 4th generation (4G) of mobile telecommunication technology. With MIMO and OFDM combined, visible light communication (VLC) system's diversity gain is increase, yet system capacity for dispersive channels is also enhanced. Moreover, with the emerging massive MIMO-OFDM VLC system, there are significant advantages than smaller systems' such as channel hardening, further increasing of energy efficiency (EE) and spectral efficiency (SE) based on law of large number. This paper addresses one of the major technological challenges, system architecture design, which was solved by semispherical beehive structure (SBS) receiver and so that diversity gain can be identified and applied in Massive MIMO VLC system. Simulation results shows that the proposed design clearly presents a spatial diversity over conventional VLC systems.

Repair of massively defected hemi-joints using demineralized osteoarticular allografts with protected cartilage.

PubMed

Li, Siming; Yang, Xiaohong; Tang, Shenghui; Zhang, Xunmeng; Feng, Zhencheng; Cui, Shuliang

2015-08-01

Surgical replacement of massively defected joints necessarily relies on osteochondral grafts effective to both of bone and cartilage. Demineralized bone matrix (DBM) retains the osteoconductivity but destroys viable chondrocytes in the cartilage portion essential for successful restoration of defected joints. This study prepared osteochondral grafts of DBM with protected cartilage. Protected cartilage portions was characterized by cellular and molecular biology and the grafts were allogenically used for grafting. Protected cartilage showed similar histomorphological structure and protected proteins estimated by total proteins and cartilage specific proteins as in those of fresh controls when DBMs were generated in bone portions. Such grafts were successfully used for simultaneously repair of bone and cartilage in massively defected osteoarticular joints within 16 weeks post-surgery. These results present an allograft with clinical potential for simultaneous restoration of bone and cartilage in defected joints.

Multiresonance modes in sine–Gordon brane models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cruz, W.T., E-mail: wilamicruz@gmail.com; Maluf, R.V., E-mail: r.v.maluf@fisica.ufc.br; Dantas, D.M., E-mail: davi@fisica.ufc.br

2016-12-15

In this work, we study the localization of the vector gauge field in two five-dimensional braneworlds generated by scalar fields coupled to gravity. The sine–Gordon like potentials are employed to produce different thick brane setups. A zero mode localized is obtained, and we show the existence of reverberations with the wave solutions indicating a quasi-localized massive mode. More interesting results are achieved when we propose a double sine–Gordon potential to the scalar field. The resulting thick brane shows a more detailed topology with the presence of an internal structure composed by two kinks. The massive spectrum of the gauge fieldmore » is revalued on this scenario revealing the existence of various resonant modes. Furthermore, we compute the corrections to Coulomb law coming from these massive KK vector modes in these thick scenarios, which is concluded that the dilaton parameter regulates these corrections.« less

SED Modeling of 20 Massive Young Stellar Objects

NASA Astrophysics Data System (ADS)

Tanti, Kamal Kumar

In this paper, we present the spectral energy distributions (SEDs) modeling of twenty massive young stellar objects (MYSOs) and subsequently estimated different physical and structural/geometrical parameters for each of the twenty central YSO outflow candidates, along with their associated circumstellar disks and infalling envelopes. The SEDs for each of the MYSOs been reconstructed by using 2MASS, MSX, IRAS, IRAC & MIPS, SCUBA, WISE, SPIRE and IRAM data, with the help of a SED Fitting Tool, that uses a grid of 2D radiative transfer models. Using the detailed analysis of SEDs and subsequent estimation of physical and geometrical parameters for the central YSO sources along with its circumstellar disks and envelopes, the cumulative distribution of the stellar, disk and envelope parameters can be analyzed. This leads to a better understanding of massive star formation processes in their respective star forming regions in different molecular clouds.

Massive problem reports mining and analysis based parallelism for similar search

NASA Astrophysics Data System (ADS)

Zhou, Ya; Hu, Cailin; Xiong, Han; Wei, Xiafei; Li, Ling

2017-05-01

Massive problem reports and solutions accumulated over time and continuously collected in XML Spreadsheet (XMLSS) format from enterprises and organizations, which record a series of comprehensive description about problems that can help technicians to trace problems and their solutions. It's a significant and challenging issue to effectively manage and analyze these massive semi-structured data to provide similar problem solutions, decisions of immediate problem and assisting product optimization for users during hardware and software maintenance. For this purpose, we build a data management system to manage, mine and analyze these data search results that can be categorized and organized into several categories for users to quickly find out where their interesting results locate. Experiment results demonstrate that this system is better than traditional centralized management system on the performance and the adaptive capability of heterogeneous data greatly. Besides, because of re-extracting topics, it enables each cluster to be described more precise and reasonable.

The impact pseudotachylitic breccia controversy: Insights from first isotope analysis of Vredefort impact-generated melt rocks

NASA Astrophysics Data System (ADS)

Reimold, Wolf Uwe; Hauser, Natalia; Hansen, Bent T.; Thirlwall, Matthew; Hoffmann, Marie

2017-10-01

Besides impact melt rock, several large terrestrial impact structures, notably the Sudbury (Canada) and Vredefort (South Africa) structures, exhibit considerable occurrences of a second type of impact-generated melt rock, so-called pseudotachylitic breccia (previously often termed ;pseudotachylite; - the term today reserved in structural geology for friction melt in shear or fault zones). At the Vredefort Dome, the eroded central uplift of the largest and oldest known terrestrial impact structure, pseudotachylitic breccia is well-exposed, with many massive occurrences of tens of meters width and many hundreds of meters extent. Genesis of these breccias has been discussed variably in terms of melt formation due to friction melting, melting due to decompression after initial shock compression, decompression melting upon formation/collapse of a central uplift, or a combination of these processes. In addition, it was recently suggested that they could have formed by the infiltration of impact melt into the crater floor, coming off a coherent melt sheet and under assimilation of wall rock; even seismic shaking has been invoked. Field evidence for generation of such massive melt bodies by friction on large shear/fault zones is missing. Also, no evidence for the generation of massive pseudotachylitic breccias in rocks of low to moderate shock degree by melting upon pressure release after shock compression has been demonstrated. The efficacy of seismic shaking to achieve sufficient melting as a foundation for massive pseudotachylitic melt generation as typified by the breccias of the Sudbury and Vredefort structures has so far remained entirely speculative. The available petrographic and chemical evidence has, thus, been interpreted to favor either decompression melting (i.e., in situ generation of melt) upon central uplift collapse, or the impact melt infiltration hypothesis. Importantly, all the past clast population and chemical analyses have invariably supported an origin of these breccias from local lithologies only. Here, the first Rb-Sr, Sm-Nd, and U-Pb isotopic data for Vredefort pseudotachylitic breccias and their host rocks, in comparison to data for Vredefort Granophyre (impact melt rock), are presented. They strongly support that the pseudotachylitic breccias were exclusively formed from local precursor lithologies - in agreement with earlier isotopic results for Sudbury Breccia and chemical results for Vredefort pseudotachylitic breccias. A contribution from a Granophyre-like impact melt component to form Vredefort pseudotachylitic breccia is not indicated. The most likely process for the genesis of voluminous pseudotachylitic breccias in large impact structures remains decompression melting upon formation and collapse of the central uplift, during the modification stage of impact cratering.

Satellite dwarf galaxies in a hierarchical universe: the prevalence of dwarf-dwarf major mergers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deason, Alis; Wetzel, Andrew; Garrison-Kimmel, Shea, E-mail: alis@ucolick.org

Mergers are a common phenomenon in hierarchical structure formation, especially for massive galaxies and clusters, but their importance for dwarf galaxies in the Local Group remains poorly understood. We investigate the frequency of major mergers between dwarf galaxies in the Local Group using the ELVIS suite of cosmological zoom-in dissipationless simulations of Milky Way- and M31-like host halos. We find that ∼10% of satellite dwarf galaxies with M {sub star} > 10{sup 6} M {sub ☉} that are within the host virial radius experienced a major merger of stellar mass ratio closer than 0.1 since z = 1, with amore » lower fraction for lower mass dwarf galaxies. Recent merger remnants are biased toward larger radial distance and more recent virial infall times, because most recent mergers occurred shortly before crossing within the virial radius of the host halo. Satellite-satellite mergers also occur within the host halo after virial infall, catalyzed by the large fraction of dwarf galaxies that fell in as part of a group. The merger fraction doubles for dwarf galaxies outside of the host virial radius, so the most distant dwarf galaxies in the Local Group are the most likely to have experienced a recent major merger. We discuss the implications of these results on observable dwarf merger remnants, their star formation histories, the gas content of mergers, and massive black holes in dwarf galaxies.« less

Sagan Lecture : Exploring Titan, An Earth-like Organic Paradise

NASA Astrophysics Data System (ADS)

Lorenz, R. D.

2007-12-01

Saturn's giant moon Titan has been called many things - 'The Mars of the Outer Solar System', 'A Fiercely-Frozen Echo of the Early Earth', 'A Place Like Home'- indeed, 'The Whole ball of Wax'. These various appelations reflect the richness and bewildering complexity of this most fascinating world which bears comparisons with both the terrestrial planets as well as other icy satellites. Titan's thick but dynamic atmosphere sculpts its surface with tidal winds and methane monsoons, and its climate has competing greenhouse and antigreenhouse effects as well as a seasonal polar haze structure analogous to the Earth's ozone hole. Titan is striking also in its massive organic inventory - its dunes and lakes make up an exposed carbon reservoir hundreds of times more massive than all of Earth's fossil fuels. At least part of this organic inventory has been processed by transient exposures to liquid water, in impact melt sheets and cryovolcanic flows (a scenario first pointed out by Thompson and Sagan in 1991). This aqueous chemical interaction is known from terrestrial laboratory experiments to yield amino acids, pyrimidines and other building blocks of living molecular systems. How far these chemical systems might evolve on geological, as opposed to laboratory, scales of space and time on Titan is completely unknown, but must surely be interesting to find out. The talk will review some of the surprising findings from Cassini-Huygens, their lessons for us here on Earth, and what future Titan exploration may tell us about the origins of worlds and the origins of life.

Luminous quasars do not live in the most overdense regions of galaxies at z ˜ 4

NASA Astrophysics Data System (ADS)

Uchiyama, Hisakazu; Toshikawa, Jun; Kashikawa, Nobunari; Overzier, Roderik; Chiang, Yi-Kuan; Marinello, Murilo; Tanaka, Masayuki; Niino, Yuu; Ishikawa, Shogo; Onoue, Masafusa; Ichikawa, Kohei; Akiyama, Masayuki; Coupon, Jean; Harikane, Yuichi; Imanishi, Masatoshi; Kodama, Tadayuki; Komiyama, Yutaka; Lee, Chien-Hsiu; Lin, Yen-Ting; Miyazaki, Satoshi; Nagao, Tohru; Nishizawa, Atsushi J.; Ono, Yoshiaki; Ouchi, Masami; Wang, Shiang-Yu

2018-01-01

We present the cross-correlation between 151 luminous quasars (MUV < -26) and 179 protocluster candidates at z ˜ 3.8, extracted from the Wide imaging survey (˜121 deg2) performed as part of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). We find that only two out of 151 quasars reside in regions that are more overdense compared to the average field at >4 σ. The distributions of the distances between quasars and the nearest protoclusters and the significance of the overdensity at the positions of quasars are statistically identical to those found for g-dropout galaxies, suggesting that quasars tend to reside in almost the same environment as star-forming galaxies at this redshift. Using stacking analysis, we find that the average density of g-dropout galaxies around quasars is slightly higher than that around g-dropout galaxies on 1.0-2.5 pMpc scales, while at <0.5 pMpc that around quasars tends to be lower. We also find that quasars with higher UV luminosity or with more massive black holes tend to avoid the most overdense regions, and that the quasar near-zone sizes are anti-correlated with overdensity. These findings are consistent with a scenario in which luminous quasars at z ˜ 4 reside in structures that are less massive than those expected for the progenitors of today's rich clusters of galaxies, and possibly that luminous quasars may be suppressing star formation in their close vicinity.

Computational mechanics analysis tools for parallel-vector supercomputers

NASA Technical Reports Server (NTRS)

Storaasli, Olaf O.; Nguyen, Duc T.; Baddourah, Majdi; Qin, Jiangning

1993-01-01

Computational algorithms for structural analysis on parallel-vector supercomputers are reviewed. These parallel algorithms, developed by the authors, are for the assembly of structural equations, 'out-of-core' strategies for linear equation solution, massively distributed-memory equation solution, unsymmetric equation solution, general eigensolution, geometrically nonlinear finite element analysis, design sensitivity analysis for structural dynamics, optimization search analysis and domain decomposition. The source code for many of these algorithms is available.

Characterizing Axial Stiffness of Individual Batter Piles with Emphasis on Elevated, Laterally Loaded, Clustered Pile Groups

DTIC Science & Technology

2016-11-01

1 1.3 Analyzing massive concrete pile-founded structures .................................................. 1 1.4 Pile...at the impact deck for the Lock and Dam 3 structural system at each incremental analysis step with C33=0.55...55 Table 4.2. Axial force, pile cap moment, and mudline moment for the three piles in the Lock and Dam 3 structural system at each

Tracking coherent structures in massively-separated and turbulent flows

NASA Astrophysics Data System (ADS)

Rockwood, Matthew; Huang, Yangzi; Green, Melissa

2018-01-01

Coherent vortex structures are tracked in simulations of massively-separated and turbulent flows. Topological Lagrangian saddle points are found using intersections of the positive and negative finite-time Lyapunov exponent ridges, and these points are then followed in order to track individual coherent structure motion both in a complex interacting three-dimensional flow (turbulent channel) and during vortex formation (two-dimensional bluff body shedding). For a simulation of wall-bounded turbulence in a channel flow, tracking Lagrangian saddles shows that the average structure convection speed exhibits a similar trend as a previously published result based on velocity and pressure correlations, giving validity to the method. When this tracking method is applied in a study of a circular cylinder in cross-flow it shows that Lagrangian saddles rapidly accelerate away from the cylinder surface as the vortex sheds. This saddle behavior is compared with the time-resolved static pressure distribution on the circular cylinder, yielding locations on a cylinder surface where common sensors could detect this phenomenon, which is not available from force measurements or vortex circulation calculations. The current method of tracking coherent structures yields insight into the behavior of the coherent structures in both of the diverse flows presented, highlighting the breadth of its potential application.

Structural changes of homodimers in the PDB.

PubMed

Koike, Ryotaro; Amemiya, Takayuki; Horii, Tatsuya; Ota, Motonori

2018-04-01

Protein complexes are involved in various biological phenomena. These complexes are intrinsically flexible, and structural changes are essential to their functions. To perform a large-scale automated analysis of the structural changes of complexes, we combined two original methods. An application, SCPC, compares two structures of protein complexes and decides the match of binding mode. Another application, Motion Tree, identifies rigid-body motions in various sizes and magnitude from the two structural complexes with the same binding mode. This approach was applied to all available homodimers in the Protein Data Bank (PDB). We defined two complex-specific motions: interface motion and subunit-spanning motion. In the former, each subunit of a complex constitutes a rigid body, and the relative movement between subunits occurs at the interface. In the latter, structural parts from distinct subunits constitute a rigid body, providing the relative movement spanning subunits. All structural changes were classified and examined. It was revealed that the complex-specific motions were common in the homodimers, detected in around 40% of families. The dimeric interfaces were likely to be small and flat for interface motion, while large and rugged for subunit-spanning motion. Interface motion was accompanied by a drastic change in contacts at the interface, while the change in the subunit-spanning motion was moderate. These results indicate that the interface properties of homodimers correlated with the type of complex-specific motion. The study demonstrates that the pipeline of SCPC and Motion Tree is useful for the massive analysis of structural change of protein complexes. Copyright © 2017 Elsevier Inc. All rights reserved.

A Compact Group of Galaxies at z = 2.48 Hosting an AGN-driven Outflow

NASA Astrophysics Data System (ADS)

Shih, Hsin-Yi; Stockton, Alan

2015-12-01

We present observations of a remarkable compact group of galaxies at z = 2.48. Four galaxies, all within 40 kpc of each other, surround a powerful high-redshift radio source. This group comprises two compact red passive galaxies and a pair of merging galaxies. One of the red galaxies, with an apparent stellar mass of 3.6 × 1011M⊙ and an effective radius of 470 pc, is one of the most extreme examples of a massive quiescent compact galaxy found so far. One of the pair of merging galaxies hosts the active galactic nucleus (AGN) producing the large powerful radio structure. The merger is massive and enriched, consistent with the mass-metallicity relation expected at this redshift. Close to the merging nuclei, the emission lines exhibit broad and asymmetric profiles that suggest outflows powered either by a very young expanding radio jet or by AGN radiation. At ≳50 kpc from the system, we found a fainter extended-emission region that may be a part of a radio-jet-driven outflow. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The work is also based, in part, on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

Fermi Research Alliance LLC

Science.gov Websites

dark matter structure in universe The findings - the most accurate made of the universe's present large -scale structure - support the dark matter/dark energy model. Read More Muon g-2 Muon magnet's moment has massive international experiment. Read More Dark Energy Camera DES reveals most accurate measurement of

RCW 108: Massive Young Stars Trigger Stellar Birth

NASA Technical Reports Server (NTRS)

2008-01-01

RCW 108 is a region where stars are actively forming within the Milky Way galaxy about 4,000 light years from Earth. This is a complicated region that contains young star clusters, including one that is deeply embedded in a cloud of molecular hydrogen. By using data from different telescopes, astronomers determined that star birth in this region is being triggered by the effect of nearby, massive young stars.

This image is a composite of X-ray data from NASA's Chandra X-ray Observatory (blue) and infrared emission detected by NASA's Spitzer Space Telescope (red and orange). More than 400 X-ray sources were identified in Chandra's observations of RCW 108. About 90 percent of these X-ray sources are thought to be part of the cluster and not stars that lie in the field-of-view either behind or in front of it. Many of the stars in RCW 108 are experiencing the violent flaring seen in other young star-forming regions such as the Orion nebula. Gas and dust blocks much of the X-rays from the juvenile stars located in the center of the image, explaining the relative dearth of Chandra sources in this part of the image.

The Spitzer data show the location of the embedded star cluster, which appears as the bright knot of red and orange just to the left of the center of the image. Some stars from a larger cluster, known as NGC 6193, are also visible on the left side of the image. Astronomers think that the dense clouds within RCW 108 are in the process of being destroyed by intense radiation emanating from hot and massive stars in NGC 6193.

Taken together, the Chandra and Spitzer data indicate that there are more massive star candidates than expected in several areas of this image. This suggests that pockets within RCW 108 underwent localized episodes of star formation. Scientists predict that this type of star formation is triggered by the effects of radiation from bright, massive stars such as those in NGC 6193. This radiation may cause the interior of gas clouds in RCW 108 to be compressed, leading to gravitational collapse and the formation of new stars.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrett, Brian; Brightwell, Ronald B.; Grant, Ryan

This report presents a specification for the Portals 4 networ k programming interface. Portals 4 is intended to allow scalable, high-performance network communication betwee n nodes of a parallel computing system. Portals 4 is well suited to massively parallel processing and embedded syste ms. Portals 4 represents an adaption of the data movement layer developed for massively parallel processing platfor ms, such as the 4500-node Intel TeraFLOPS machine. Sandia's Cplant cluster project motivated the development of Version 3.0, which was later extended to Version 3.3 as part of the Cray Red Storm machine and XT line. Version 4 is tarmore » geted to the next generation of machines employing advanced network interface architectures that support enh anced offload capabilities.« less

Heavy-quark production in massless quark scattering at two loops in QCD

NASA Astrophysics Data System (ADS)

Czakon, M.; Mitov, A.; Moch, S.

2007-07-01

We present the two-loop virtual QCD corrections to the production of heavy quarks in the quark-anti-quark annihilation channel in the limit when all kinematical invariants are large compared to the mass of the heavy quark. Our result is exact up to terms suppressed by powers of the heavy-quark mass. The derivation is based on a simple relation between massless and massive scattering amplitudes in gauge theories proposed recently by two of the authors as well as a direct calculation of the massive amplitude at two loops. The results presented here form an important part of the next-to-next-to-leading order QCD contributions to heavy-quark production in hadron-hadron collisions.

The Portals 4.0 network programming interface.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrett, Brian W.; Brightwell, Ronald Brian; Pedretti, Kevin

2012-11-01

This report presents a specification for the Portals 4.0 network programming interface. Portals 4.0 is intended to allow scalable, high-performance network communication between nodes of a parallel computing system. Portals 4.0 is well suited to massively parallel processing and embedded systems. Portals 4.0 represents an adaption of the data movement layer developed for massively parallel processing platforms, such as the 4500-node Intel TeraFLOPS machine. Sandias Cplant cluster project motivated the development of Version 3.0, which was later extended to Version 3.3 as part of the Cray Red Storm machine and XT line. Version 4.0 is targeted to the next generationmore » of machines employing advanced network interface architectures that support enhanced offload capabilities.« less

Treatment of Acute Massive Pulmonary Embolism by Streptokinase during Labour and Delivery

PubMed Central

Hall, R. J. C.; Young, C.; Sutton, G. C.; Cambell, S.

1972-01-01

A 29-year-old woman sustained an acute massive pulmonary embolism in the 32nd week of pregnancy. Rapid clinical improvement followed the use of streptokinase. Treatment was continued for 41 hours, including labour and the first three hours after delivery. There was slow but severe postpartum haemorrhage. Partial uterine atony occurred, and may have been due, at least in part, to fibrin degradation products arising from thrombolysis. No adverse effects were noted in the baby. Our experience suggests that streptokinase may be given during labour but that an oxytocic agent may be needed; and that reversal of fibrinolysis before delivery is best achieved by the use of aprotinin (Trasylol) rather than aminocaproic acid. Imagesp647-a PMID:4539533

Fracturing alliance improves profitability of Lost Hills field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stewart, M.; Stewart, D.; Gaona, M.

1994-11-21

About 2 billion bbl of oil-in-place are present in the massive diatomite deposits of California's Lost Hills field, about 45 miles north-west of Bakersfield, Calif. Massive hydraulic fracturing treatments, 2,500-3,000 lb of proppant/net perforated ft, are an integral part of developing these reserves. An exclusive fracturing alliance initiated in 1990 between Chevron U.S.A. and Schlumberger Dowell has improved profitability of the Los Hills field. the paper describes the geology, the field before 1987, the 1987--90 period when hydraulic fracturing stimulation was found to be very costly, and after 1990 when the alliance was formed. The paper also describes the fracturingmore » fluid, proppants, engineering evaluation, and execution of the job.« less

Molecular gas in the halo fuels the growth of a massive cluster galaxy at high redshift.

PubMed

Emonts, B H C; Lehnert, M D; Villar-Martín, M; Norris, R P; Ekers, R D; van Moorsel, G A; Dannerbauer, H; Pentericci, L; Miley, G K; Allison, J R; Sadler, E M; Guillard, P; Carilli, C L; Mao, M Y; Röttgering, H J A; De Breuck, C; Seymour, N; Gullberg, B; Ceverino, D; Jagannathan, P; Vernet, J; Indermuehle, B T

2016-12-02

The largest galaxies in the universe reside in galaxy clusters. Using sensitive observations of carbon monoxide, we show that the Spiderweb galaxy-a massive galaxy in a distant protocluster-is forming from a large reservoir of molecular gas. Most of this molecular gas lies between the protocluster galaxies and has low velocity dispersion, indicating that it is part of an enriched intergalactic medium. This may constitute the reservoir of gas that fuels the widespread star formation seen in earlier ultraviolet observations of the Spiderweb galaxy. Our results support the notion that giant galaxies in clusters formed from extended regions of recycled gas at high redshift. Copyright © 2016, American Association for the Advancement of Science.

Entanglement entropy of AdS5 × S5 with massive flavors

NASA Astrophysics Data System (ADS)

Hu, Sen; Wu, Guozhen

2018-01-01

We consider backreacted AdS5 × S5 coupled with Nf massive flavors introduced by D7 branes. The backreacted geometry is in the Veneziano limit with fixed Nf/Nc. By dividing one of the directions into a line segment with length l, we get two subspaces. Then we calculate the entanglement entropy between them. With the method of [I. R. Klebanov, D. Kutasov and A. Murugan, Nucl. Phys. B 796, 274 (2008)], we are able to find the cut-off independent part of the entanglement entropy and finally find that this geometry shows no confinement/deconfinement phase transition at zero temperature from the holographic entanglement entropy point of view similar to the case in pure AdS5 × S5.

Local election: does bureaucracy become one of main political power?

NASA Astrophysics Data System (ADS)

Amin, Muryanto; Musthafa Sembiring, Walid

2018-03-01

This writing aims to analyze the emergence of bureaucracy as one of political power in local level after the local election is held in Indonesia. Due to information authorization, media network, and stable structure, the bureaucracy soon transforms into political power which can compete with the other political power at the local level. In Medan local election in 2010 and 2015 has evidently proven the power of bureaucracy network in winning the bureaucrat-background candidates. As methods of the research, the researcher held a Focus-Group Discussion (FGD) and had an in-depth interview with ten bureaucracy elites in Medan and local political elites. The observation and Focus-Group Discussion (FGD) are analyzed using qualitative analysis technique typology. The result states that the bureaucracy network in Medan has been used in a massive way as the political power of winning. The structure of bureaucracy – from the top to the low – is involved in the winning. The most governmental programs were applied to attract the mass’ sympathy toward the candidates. The bureaucratic proximity to media network is also used to do a campaign in a massive way. The conclusion of the research is that bureaucracy emerges as a new, massive, effective local political power in the local election.

Skeletal Strength and Skeletogenetic Mechanisms Over Phanerozoic Time

NASA Astrophysics Data System (ADS)

Constantz, B. R.

2004-12-01

Mineralized skeletons have a remarkable range of mechanical properties with respect to strength and durability. Measurements of skeletal mechanical properties show that taxonomic groups with relatively simple, `physiochemically-dominated' modes of mineralization possess skeletal strengths and durabilities that are among the lowest of any known mineralized skeletons. Organisms with relatively sophisticated, `biologically-dominated' modes of mineralization have mechanical properties among the highest values known for any materials. These extraordinarily strong and durable skeletal materials are found in mollusks, echinoderms, vertebrates, and arthropods, which are groups with primarily mobile ecological habits. These skeletons are frequently lightweight, non-massive skeletons with little phenotypic variation. By contrast, dominant reef framework builders and reef sediment formers, with physiochemically-dominated modes of mineralization, have non-mobile ecological habits and construct massive, phenotypically plastic skeletons, possessing extremely poor mechanical properties. Endolithic organisms that further degrade the mechanical properties of the mineralized skeletons of reef builders frequently ravage their massive skeletons. As a result, the skeletons of these groups commonly fragment, and play a central role in reef establishment and maintenance, as they are incorporated in reefal, wave-resistant carbonate buildups. Scleractinian corals have a physiochemically-dominated mode of mineralization and are the dominant modern reef framework builders. Mechanical properties of modern aragonitic scleractinian coral skeletons, tested alive, demonstrate skeletal strengths that are orders of magnitude lower than those seen in mollusks, echinoderms, vertebrates, and arthropods. Rudist bivalves, the dominant reef framework-building group of the Cretaceous, show prolific, massive, highly variable, calcific skeletal elements with structures similar to some reef-forming modern, non-mobile mollusks and the skeletons of other organisms with physiochemically-dominated modes of mineralization. Many aspects of the ecological habits of reef-framework building scleractinians and rudsits are similar, including relatively high skeletal growth rates, which produce massive skeletons and wave-resistant structures with entrapped bioclastic sediments. The principal adaptive role of mineralization in reef framework building groups appears to be the rapid production of massive, brittle, wave-resistant mineralized skeletons. The physiochemically-dominated mode of mineralization of these reef framework builders appears to have made them susceptible to secular variations in Phanerozoic seawater during `calcite' and `aragonite' seas, favoring scleractinians in aragonite seas and rudists during the Cretaceous calcite episode. By contrast, most mobile mollusks, echinoderms, vertebrates, and arthropods appear relatively unaffected by secular variations in seawater chemistry over the Phanerozoic

Comparison of Clinical and Structural Outcomes by Subscapularis Tendon Status in Massive Rotator Cuff Tear.

PubMed

Lee, Sung Hyun; Nam, Dae Jin; Kim, Se Jin; Kim, Jeong Woo

2017-09-01

The subscapularis tendon is essential in maintaining normal glenohumeral biomechanics. However, few studies have addressed the outcomes of tears extending to the subscapularis tendon in massive rotator cuff tears. To assess the clinical and structural outcomes of arthroscopic repair of massive rotator cuff tears involving the subscapularis. Cohort study; Level of evidence, 3. Between January 2010 and January 2014, 122 consecutive patients with massive rotator cuff tear underwent arthroscopic rotator cuff repair. Overall, 122 patients were enrolled (mean age, 66 years; mean follow-up period, 39.5 months). Patients were categorized into 3 groups based on subscapularis tendon status: intact subscapularis tendon (I group; n = 45), tear involving less than the superior one-third (P group; n = 35), and tear involving more than one-third of the subscapularis tendon (C group; n = 42). All rotator cuff tears were repaired; however, subscapularis tendon tears involving less than the superior one-third in P group were only debrided. Pain visual analog scale, Constant, and American Shoulder and Elbow Surgeons scores and passive range of motion were measured preoperatively and at the final follow-up. Rotator cuff integrity, global fatty degeneration index, and occupation ratio were determined via magnetic resonance imaging preoperatively and 6 months postoperatively. We identified 37 retears (31.1%) based on postoperative magnetic resonance imaging evaluation. Retear rate in patients in the C group (47.6%) was higher than that in the I group (22.9%) or P group (20.0%) ( P = .011). Retear subclassification based on the involved tendons showed that subsequent subscapularis tendon retears were noted in only the C group. The improvement in clinical scores after repair was statistically significant in all groups but not different among the groups. Between-group comparison showed significant differences in preoperative external rotation ( P = .021). However, no statistically significant difference was found in any shoulder range of motion measurements after surgery. Arthroscopic repair of massive tears results in substantial improvements in shoulder function, despite the presence of combined subscapularis tears. However, this study showed a high failure rate of massive posterosuperior rotator cuff tear repair extending more than one-third of the subscapularis tendon. When combined subscapularis tendon tear was less than the superior one-third of the subscapularis tendon, arthroscopic debridement was a reasonable treatment method where comparable clinical and anatomic outcomes could be expected.

Eta Carinae: An Astrophysical Laboratory

NASA Technical Reports Server (NTRS)

Gull, T.

2008-01-01

In the 1840s, Eta Carinae, a massive binary near the end of its hydrogen burning cycle, ejected at least ten solar masses of material rich in nitrogen at the expense of carbon and oxygen. The resultant chemistry has led to a most peculiar mix of metals, molecules and dust. We identify thousands of nebular absorption lines of ions including Fe, Ni, V, Sr, Sc and molecules including H2, CH, OH, but no CO. Today we see a wind-enshrouded massive binary in the center of an expanding neutral hourglass and skirt. A similar ionized internal structure is associated with a lesser ejection of the 1890s. Both systems respond to the 5.54-year modulation of X-ray and ultraviolet radiation as the less massive, hotter companion plunges through the extended wind of the more massive, cooler primary. Observations and models are being brought together to understand the properties of the wind-enshrouded central binary. In turn we are learning much atomic spectroscopy, what molecules form in oxygen-and carbon-deprived environments and potentially about a dust that is quite different from the interstellar dust. As the next periastron occurs in January 2009, a number of observing teams are preparing to test these models with new observations.

Weak and compact radio emission in early massive star formation regions: an ionized jet toward G11.11–0.12P1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosero, V.; Hofner, P.; McCoy, M.

2014-12-01

We report 1.3 cm and 6 cm continuum observations toward the massive proto-stellar candidate G11.11–0.12P1 using the Karl G. Jansky Very Large Array. We detect a string of four unresolved radio continuum sources coincident with the mid-infrared source in G11P1. The continuum sources have positive spectral indices consistent with a thermal (free-free) ionized jet. The most likely origins of the ionized gas are shocks due to the interaction of a stellar wind with the surrounding high-density material. We also present NIR United Kingdom Infrared Telescope (UKIRT) archival data that show an extended structure detected only at K band (2.2 μm),more » which is oriented perpendicular to the jet, and that may be scattered light from a circumstellar disk around the massive protostar. Our observations plus the UKIRT archival data thus provide new evidence that a disk/jet system is present in the massive proto-stellar candidate located in the G11.11–0.12P1 core.« less

An Effective Massive Sensor Network Data Access Scheme Based on Topology Control for the Internet of Things.

PubMed

Yi, Meng; Chen, Qingkui; Xiong, Neal N

2016-11-03

This paper considers the distributed access and control problem of massive wireless sensor networks' data access center for the Internet of Things, which is an extension of wireless sensor networks and an element of its topology structure. In the context of the arrival of massive service access requests at a virtual data center, this paper designs a massive sensing data access and control mechanism to improve the access efficiency of service requests and makes full use of the available resources at the data access center for the Internet of things. Firstly, this paper proposes a synergistically distributed buffer access model, which separates the information of resource and location. Secondly, the paper divides the service access requests into multiple virtual groups based on their characteristics and locations using an optimized self-organizing feature map neural network. Furthermore, this paper designs an optimal scheduling algorithm of group migration based on the combination scheme between the artificial bee colony algorithm and chaos searching theory. Finally, the experimental results demonstrate that this mechanism outperforms the existing schemes in terms of enhancing the accessibility of service requests effectively, reducing network delay, and has higher load balancing capacity and higher resource utility rate.

Star-disc interaction in galactic nuclei: formation of a central stellar disc

NASA Astrophysics Data System (ADS)

Panamarev, Taras; Shukirgaliyev, Bekdaulet; Meiron, Yohai; Berczik, Peter; Just, Andreas; Spurzem, Rainer; Omarov, Chingis; Vilkoviskij, Emmanuil

2018-05-01

We perform high-resolution direct N-body simulations to study the effect of an accretion disc on stellar dynamics in an active galactic nucleus (AGN). We show that the interaction of the nuclear stellar cluster (NSC) with the gaseous accretion disc (AD) leads to formation of a stellar disc in the central part of the NSC. The accretion of stars from the stellar disc on to the super-massive black hole is balanced by the capture of stars from the NSC into the stellar disc, yielding a stationary density profile. We derive the migration time through the AD to be 3 per cent of the half-mass relaxation time of the NSC. The mass and size of the stellar disc are 0.7 per cent of the mass and 5 per cent of the influence radius of the super-massive black hole. An AD lifetime shorter than the migration time would result in a less massive nuclear stellar disc. The detection of such a stellar disc could point to past activity of the hosting galactic nucleus.

BLOWING COSMIC BUBBLES

NASA Technical Reports Server (NTRS)

2002-01-01

This NASA Hubble Space Telescope image reveals an expanding shell of glowing gas surrounding a hot, massive star in our Milky Way Galaxy. This shell is being shaped by strong stellar winds of material and radiation produced by the bright star at the left, which is 10 to 20 times more massive than our Sun. These fierce winds are sculpting the surrounding material - composed of gas and dust - into the curve-shaped bubble. Astronomers have dubbed it the Bubble Nebula (NGC 7635). The nebula is 10 light-years across, more than twice the distance from Earth to the nearest star. Only part of the bubble is visible in this image. The glowing gas in the lower right-hand corner is a dense region of material that is getting blasted by radiation from the Bubble Nebula's massive star. The radiation is eating into the gas, creating finger-like features. This interaction also heats up the gas, causing it to glow. Scientists study the Bubble Nebula to understand how hot stars interact with the surrounding material. Credit: Hubble Heritage Team (AURA/STScI/NASA)

Outgassing of planets in relation to their obital frequencies

NASA Astrophysics Data System (ADS)

Kochemasov, G.

Planetary atmospheres as inseparable parts of their geospheres have close structural and compositional ties with underlying solid formations. The comparative wave planetology having stated that "orbits make structures" finds that two fundamental properties of all celestial bodies are most important for their structurization: movement and rotation. All bodies move in non-round keplerian elliptic (and parabolic) orbits that implies periodic change of accelerations and delivery of inertia-gravity forces producing warping waves. In rotating bodies (but all celestial bodies rotate !) these waves are ordered in 4 ortho- and diagonal directions. Having stationary character and various lengths they interfere producing positive (+), negative (-) and neutral (0) tectonic blocks. The fundamental wave 1 long 2πR give ubiquitous tectonic dichotomy, the first overtone wave 2 makes tectonic sectoring. Individual for any body waves whose lengths are inversely proportional to their orbital frequencies produce tectonic granules: higher frequency - smaller granule. The following row shows increasing granule sizes (a half of a wavelength, Earth as a scale): Titan πR/91, Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2, asteroids πR/1. One may say that Venus is tectonically "fine-grained", Earth "medium-grained", Mars "coarse-grained". The wave produced granulation indicates that fine-grained Venus is more thoroughly shaken out and released of its volatiles (degassed) than Earth and Mars. This is proved by its massive atmosphere containing a large amount of nitrogen and having very low ratio of radiogenic to primordial argon (Venus 1, Earth 300, Mars 3000). Compare "sweeping" volatiles out of Venus and Earth [1]. Venus is 3.38 times finer-grained than Earth (in the terrestrial globe there are 16.5 grains of radius πR/8, in the venusian one 55.7 grains of radius πR/12; 55.7 : 16.5=3.38). To the terrestrial wavelength 10000 km (πR/2) corresponds frequency 0.03 khz, to the venusian 6000 km (πR/3) 0.07 khz. Venusian oscillations thus 2.33 times more frequent. If a degassing difference of two planets is the square (degassing goes through surface) of the production of differences in granulation and oscillation frequencies, then Venus is 62 times more outgassed [Dv /De = (3.38 x 2.33)2 =62.1]. Actually the venusian atmosphere is 90 times more massive than the terrestrial one. Comparing Mars (1/10th of the Earth's mass) and Earth by the same method we get 920 times less massive martian atmosphere (actually only about 200 times). The discrepancy probably is due to large amounts of volatiles in soils and crust (ice, aqueous salts, zeolites) exchanging them with atmosphere under changing conditions. On contrary, Mercury is completely "shaken out", 1 dry, its would-be massive atmosphere is completely eliminated by solar wind. The smaller volatile rich Titan with high orbital frequency has an important atmosphere -probably only remnants of what was totally outgassed during eons. All Titan's dark plains (frozen methane?) are intensively warped by cross-cutting ridge-groove systems -a consequence of an important subsidence, loosing radius. So, there is an inverse relation between atmospheric masses and a volatile stock in planets. Dry Venus has a massive atmosphere, wet Mars has a weak one. Earth is in the middle: rather wet interior and an important atmosphere. Most outgassed Mercury with distinct traces of earlier contraction (escarps or lobate ledges), alas, has lost its gaseous envelope. Asteroids , next to Mars, as show carboneceous chondrites are rich in volatiles. Sharing an angular momentum between a solid body and a massive gaseous envelope enforces this body rotate slower (Venus, Mercury). This observation could perhaps explain one enigmatic situation: the larger asteroids rotate faster than smaller ones. A reason: the former less wasted their "original" momentum not spending it with loosing volatiles than the latter, more degassed. References: [1] Kochemaov G.G. (2003) Tectonically and chemically dichotomic Mars is the least outgassed of terrestrial planets // Vernadsky-Brown microsymp. 38, Oct. 27-29, 2003, Vernadsky Inst., Moscow, Russia, Abstr.,(CD-ROM). 2

Soils of the Galindez Island, Argentine archipelago, Western Antarctica

NASA Astrophysics Data System (ADS)

Abakumov, Evgeny; Parnikoza, Ivan

2015-04-01

Antarctic Peninsula is a part of Antarctica which is characterized by increased soil diversity, caused by specific of parent materials and diversity of non-vascular and vascular plants. Soils of Galindez Island have been investigated during the 18-th Ukranian Antarctic Expedition 2013/14. This Island situated in Argentine archipelago (coastal part of Antarctic Peninsula). Soils of Galindez Island presented by following types: Leptosols, Lithosols, Histic Lithosols and Leptosols and some Gleyic soils, located in lowlands and coastal parts. An average solum profile thickness is 3-19 cm which result from the small depth of debris's, underplayed by massive crystallic rocks. The permafrost layer is located within the massive rock, but not in coarse friable parent material. The soils with bird influence are widely spread both in coastal and central part of Island. In the coastal parts we can find typical Ornithosols in the penguin rockeries areas. The main aim of our investigation was characterization of soils formed under vegetation, exactly under Deschampsia antarctica Desv. localities. Argentine Islands is the central part of D. antarctica spreading area in region of Antarctic peninsula. Probably, these islands colonized by hairgrass mainly due to ornitogenic activity. So, coastal population appearance related with Larus dominicanus nest areas and feeding activity. Thus, we found typical post ornithogenic soils here. This kind of soils we also observed in population of hairgrass of Galindez mainland where it was connected with the other Antarctic bird - Catharacta maccormicki activity. Thus, the soil diversity and soil geochemistry of the Galindez Island are closely related to the activity of birds. The spatial pattern of soils, their chemistry and organic matter quality is discussed in relation with distribution of bird nesting and feeding activity.

The Role of Rotation in the Evolution of Massive Stars

NASA Technical Reports Server (NTRS)

Heap, Sara R.; Lanz, Thierry M.

2003-01-01

Recent evolutionary models of massive stars predict important effects of rotation including: increasing the rate of mass loss; lowering the effective gravity; altering the evolutionary track on the Hertzsprung-Russel Diagram (HRD); extending the main-sequence phase (both on the HR diagram and in time); and mixing of CNO-processed elements up to the stellar surface. Observations suggest that rotation is a more important factor at lower metallicities because of higher initial rotational velocities and weaker winds. This makes the Small Magellanic Cloud (SMC), a low-metallicity galaxy (Z=0.2 solar Z), an excellent environment for discerning the role of rotation in massive stars. We report on a FUSE+STIS+optical spectral analysis of 17 O-type stars in the SMC, where we found an enormous range in N abundances. Three stars in the sample have the same (low) CN abundances as the nebular material out of which they formed, namely C=0.085 solar C and N=0.034 solar N. However, more than half show N approx. solar N, an enrichment factor of 30X! Such unexpectedly high levels of N have ramifications for the evolution of massive stars including precursors to supernovae. They also raise questions about the sources of nitrogen in the early universe. This study was supported in part by grants from NASA's ADP, HST GO-7437, and FUSE B134.

Study of Remote Globular Cluster Satellites of M87

NASA Astrophysics Data System (ADS)

Sahai, Arushi; Shao, Andrew; Toloba, Elisa; Guhathakurta, Puragra; Peng, Eric W.; Zhang, Hao

2017-01-01

We present a sample of “orphan” globular clusters (GCs) with previously unknown parent galaxies, which we determine to be remote satellites of M87, a massive elliptical galaxy at the center of the Virgo Cluster of Galaxies. Because GCs were formed in the early universe along with their original parent galaxies, which were cannibalized by massive galaxies such as M87, they share similar age and chemical properties. In this study, we first confirm that M87 is the adoptive parent galaxy of our orphan GCs using photometric and spectroscopic data to analyze spatial and velocity distributions. Next, we increase the signal-to-noise ratio of our samples’ spectra through a process known as coaddition. We utilize spectroscopic absorption lines to determine the age and metallicity of our orphan GCs through comparison to stellar population synthesis models, which we then relate to the GCs’ original parent galaxies using a mass-metallicity relation. Our finding that remote GCs of M87 likely developed in galaxies with ~1010 solar masses implies that M87’s outer halo is formed of relatively massive galaxies, serving as important parameters for developing theories about the formation and evolution of massive galaxies.This research was funded in part by NASA/STScI and the National Science Foundation. Most of this work was carried out by high school students working under the auspices of the Science Internship Program at UC Santa Cruz.

iss009e23808

NASA Image and Video Library

2004-09-20

ISS009-E-23808 (20 September 2004) --- A fringing coral reef in the Red Sea is featured in this image photographed by an Expedition 9 crewmember on the International Space Station (ISS). The Sudanese coast of the Red Sea is a well known destination for divers due to clear water and abundance of coral reefs (or “shia’ab” in Arabic). According to NASA scientists studying the ISS imagery, reefs are formed primarily from precipitation of calcium carbonate by corals; massive reef structures are built over thousands of years of succeeding generations of coral. In the Red Sea, fringing reefs form on shallow shelves of less than 50 meters depth along the coastline. This photograph illustrates the intricate morphology of the reef system located along the coast between Port Sudan to the northwest and the Tokar River delta to the southeast. Close to shore, fringing reefs border the coastline. Farther offshore grows a larger, more complicated barrier reef structure. Different parts of the reef structure show up as variable shades of light blue. Deeper water channels (darker blue) define the boundaries for individual reefs within the greater barrier reef system. Such a complex pattern of reefs may translate into greater ecosystem diversity through a wide variety of local reef environments.

The Dynamics of Massive Starless Cores with ALMA

NASA Astrophysics Data System (ADS)

Tan, Jonathan C.; Kong, Shuo; Butler, Michael J.; Caselli, Paola; Fontani, Francesco

2013-12-01

How do stars that are more massive than the Sun form, and thus how is the stellar initial mass function (IMF) established? Such intermediate- and high-mass stars may be born from relatively massive pre-stellar gas cores, which are more massive than the thermal Jeans mass. The turbulent core accretion model invokes such cores as being in approximate virial equilibrium and in approximate pressure equilibrium with their surrounding clump medium. Their internal pressure is provided by a combination of turbulence and magnetic fields. Alternatively, the competitive accretion model requires strongly sub-virial initial conditions that then lead to extensive fragmentation to the thermal Jeans scale, with intermediate- and high-mass stars later forming by competitive Bondi-Hoyle accretion. To test these models, we have identified four prime examples of massive (~100 M ⊙) clumps from mid-infrared extinction mapping of infrared dark clouds. Fontani et al. found high deuteration fractions of N2H+ in these objects, which are consistent with them being starless. Here we present ALMA observations of these four clumps that probe the N2D+ (3-2) line at 2.''3 resolution. We find six N2D+ cores and determine their dynamical state. Their observed velocity dispersions and sizes are broadly consistent with the predictions of the turbulent core model of self-gravitating, magnetized (with Alfvén Mach number mA ~ 1) and virialized cores that are bounded by the high pressures of their surrounding clumps. However, in the most massive cores, with masses up to ~60 M ⊙, our results suggest that moderately enhanced magnetic fields (so that mA ~= 0.3) may be needed for the structures to be in virial and pressure equilibrium. Magnetically regulated core formation may thus be important in controlling the formation of massive cores, inhibiting their fragmentation, and thus helping to establish the stellar IMF.

Before Industrialization: A Rural Social System Base Study.

ERIC Educational Resources Information Center

Summers, Gene F.; And Others

A recent trend in American economic life has been the location of industrial complexes in traditionally rural areas. When this occurs, there are often accompanying rapid and sometimes traumatic changes in the rural community. These changes, in part, result from investment of new and massive amounts of capital, new employment opportunities,…

Controversy over Student's Art Exhibit at Yale Raises Issues of Academic Freedom

ERIC Educational Resources Information Center

Wilson, Robin

2008-01-01

This article describes the controversy surrounding a Yale University art student, Aliza Shvarts, who told the campus newspaper that she had repeatedly inseminated herself artificially and then induced abortions as part of her senior thesis. The controversy has created massive reverberations throughout academe, especially in the already hotly…

How Massive Multiplayer Online Games Incorporate Principles of Economics

ERIC Educational Resources Information Center

Barnett, Joshua H.; Archambault, Leanna

2010-01-01

Games have always been a part of the human experience. Even the earliest of civilizations created games for enjoyment and entertainment. However, the educational value of those games is a relatively recent consideration. Over the previous fifty years, scholars have questioned the potential positive lessons learned from games such as Monopoly[R],…

H-MOOC Framework: Reusing MOOCs for Hybrid Education

ERIC Educational Resources Information Center

Pérez-Sanagustín, Mar; Hilliger, Isabel; Alario-Hoyos, Carlos; Kloos, Carlos Delgado; Rayyan, Saif

2017-01-01

Since Massive Open Online Courses (MOOCs) started to become part of the scene of Higher Education (HE), many institutions have joined the race of MOOC creation. However, producing MOOCs has shown to be a cumbersome and expensive activity for HE institutions. For this reason, many universities have started to explore and experiment with hybrid…

Indigenisation of Psychology in India

ERIC Educational Resources Information Center

Dalal, Ajit K.

2011-01-01

Academic psychology which made a new beginning in India in the early part of 20th century was modelled on the Western scientific tradition. The teaching of psychology was very much on the British pattern since the colonial rule, whereas the research was mostly an extension of the Western work in India. Psychology went through massive expansion…

78 FR 79450 - Information Collection Being Reviewed by the Federal Communications Commission Under Delegated...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-30

... categories for interconnection revenue does not require massive changes to the ILECs' accounting systems and.... Title: Part 32, Uniform System of Accounts for Telecommunications Companies. Form Number: N/A. Type of...; and Account 6565, Amortization expense-other. These accounting changes are mandatory only for Class A...

75 FR 69443 - Notice of Public Information Collection(s) Being Reviewed by the Federal Communications...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-12

... interconnection revenue does not require massive changes to the ILECs' accounting systems and is a far less...: Part 32, Uniform System of Accounts for Telecommunications Companies. Form No.: N/A. Type of Review...--other. These accounting changes are mandatory only for Class A Incumbent Local Exchange Carriers (ILECs...

360 Degree Videos within a Climbing MOOC

ERIC Educational Resources Information Center

Gänsluckner, Michael; Ebner, Martin; Kamrat, Isidor

2017-01-01

In this research study a course, combining both computer-supported and face-to-face teaching using the concept of blended learning, has been designed. It is a beginners climbing course called "Klettern mit 360° Videos" (climbing with 360° videos) and the online part has been implemented as a Massive Open Online Course (MOOC). This…

The HIFI spectral survey of massive star-forming region AFGL 2591

NASA Astrophysics Data System (ADS)

Kazmierczak, Maja; van der Tak, Floris; Helmich, Frank; Chvarria, Luis; Wang, Kuo-Song; Ceccarelli, Cecilia

2013-07-01

AFGL 2591 is a massive protostellar object with a bipolar outflow. It has been widely studied before since it is a relatively isolated and nearby star-forming region. Here we present an overview of the Herschel/HIFI spectral survey, as a part of CHESS Key Project. The survey covers a frequency range from 480 up to 1240 GHz as well as some particular lines from 1267 to 1901 GHz. From the spectral survey a total of 32 species were identified. The data analysis is divided into various families of molecules, eg. CO and its isotopologues, nitrogen-bearing molecules, sulfur-bearing species, organic molecules. We will discuss different types of observed molecules and their physical parameters. The radial abundance profiles of some molecules will be presented to learn about the chemical processes leading to their formation and destruction. One of the studied molecule is ammonia, which is concentrated in the inner part of the protostellar envelope (when T > 100K i.e. where water ice evaporates), with the abundance of 3x10e-7.

THE MASS PROFILE AND SHAPE OF BARS IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G): SEARCH FOR AN AGE INDICATOR FOR BARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Taehyun; Lee, Myung Gyoon; Sheth, Kartik

2015-01-20

We have measured the radial light profiles and global shapes of bars using two-dimensional 3.6 μm image decompositions for 144 face-on barred galaxies from the Spitzer Survey of Stellar Structure in Galaxies. The bar surface brightness profile is correlated with the stellar mass and bulge-to-total (B/T) ratio of their host galaxies. Bars in massive and bulge-dominated galaxies (B/T > 0.2) show a flat profile, while bars in less massive, disk-dominated galaxies (B/T ∼ 0) show an exponential, disk-like profile with a wider spread in the radial profile than in the bulge-dominated galaxies. The global two-dimensional shapes of bars, however, are rectangular/boxy, independentmore » of the bulge or disk properties. We speculate that because bars are formed out of disks, bars initially have an exponential (disk-like) profile that evolves over time, trapping more disk stars to boxy bar orbits. This leads bars to become stronger and have flatter profiles. The narrow spread of bar radial profiles in more massive disks suggests that these bars formed earlier (z > 1), while the disk-like profiles and a larger spread in the radial profile in less massive systems imply a later and more gradual evolution, consistent with the cosmological evolution of bars inferred from observational studies. Therefore, we expect that the flatness of the bar profile can be used as a dynamical age indicator of the bar to measure the time elapsed since the bar formation. We argue that cosmic gas accretion is required to explain our results on bar profile and the presence of gas within the bar region.« less

Long-term successful arthroscopic repair of large and massive rotator cuff tears with a functional and degradable reinforcement device.

PubMed

Proctor, Christopher S

2014-10-01

Rotator cuff repair is a procedure with varying outcomes, and there has been subsequent interest in devices that reinforce the repair and enhance structural and functional outcomes. The objective of this study was to determine these outcomes for arthroscopic repair of large and massive rotator cuff tears augmented with a synthetic absorbable mesh designed specifically for reinforcement of tendon repair by imaging and clinical assessments. Consecutive arthroscopic repairs were performed on 18 patients with large to massive rotator cuff tears by use of a poly-l-lactic acid synthetic patch as a reinforcement device and fixation with 4 sutures. Patients were assessed preoperatively and at 6 months, 12 months, and a mean of 42 months after surgery by the American Shoulder and Elbow Surgeons (ASES) shoulder score to evaluate clinical performance and at 12 months by ultrasound to assess structural repair. Ultrasound showed that 15 of 18 patients had intact rotator cuff repair at 12 months; at 42 months, an additional patient had a failed repair. Patients showed improvement in the ASES shoulder score from 25 preoperatively to 71 at 12 months and 70 at 42 months after surgery. Patients with intact rotator cuff (n = 14) at 42 months had an ASES shoulder score of 82. The poly-l-lactic acid bioabsorbable patch designed specifically to reinforce the surgical repair of tendons supported successful repair of large to massive rotator cuff tears in 83% of patients at 12 months after surgery and 78% of patients at 42 months after surgery, with substantial functional improvement. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

The impact of baryons on massive galaxy clusters: halo structure and cluster mass estimates

NASA Astrophysics Data System (ADS)

Henson, Monique A.; Barnes, David J.; Kay, Scott T.; McCarthy, Ian G.; Schaye, Joop

2017-03-01

We use the BAHAMAS (BAryons and HAloes of MAssive Systems) and MACSIS (MAssive ClusterS and Intercluster Structures) hydrodynamic simulations to quantify the impact of baryons on the mass distribution and dynamics of massive galaxy clusters, as well as the bias in X-ray and weak lensing mass estimates. These simulations use the subgrid physics models calibrated in the BAHAMAS project, which include feedback from both supernovae and active galactic nuclei. They form a cluster population covering almost two orders of magnitude in mass, with more than 3500 clusters with masses greater than 1014 M⊙ at z = 0. We start by characterizing the clusters in terms of their spin, shape and density profile, before considering the bias in both weak lensing and hydrostatic mass estimates. Whilst including baryonic effects leads to more spherical, centrally concentrated clusters, the median weak lensing mass bias is unaffected by the presence of baryons. In both the dark matter only and hydrodynamic simulations, the weak lensing measurements underestimate cluster masses by ≈10 per cent for clusters with M200 ≤ 1015 M⊙ and this bias tends to zero at higher masses. We also consider the hydrostatic bias when using both the true density and temperature profiles, and those derived from X-ray spectroscopy. When using spectroscopic temperatures and densities, the hydrostatic bias decreases as a function of mass, leading to a bias of ≈40 per cent for clusters with M500 ≥ 1015 M⊙. This is due to the presence of cooler gas in the cluster outskirts. Using mass weighted temperatures and the true density profile reduces this bias to 5-15 per cent.

Magnetic solutions in Einstein-massive gravity with linear and nonlinear fields

NASA Astrophysics Data System (ADS)

Hendi, Seyed Hossein; Panah, Behzad Eslam; Panahiyan, Shahram; Momennia, Mehrab

2018-06-01

The solutions of U(1) gauge-gravity coupling is one of the interesting models for analyzing the semi-classical nature of spacetime. In this regard, different well-known singular and nonsingular solutions have been taken into account. The paper at hand investigates the geometrical properties of the magnetic solutions by considering Maxwell and power Maxwell invariant (PMI) nonlinear electromagnetic fields in the context of massive gravity. These solutions are free of curvature singularity, but have a conic one which leads to presence of deficit/surplus angle. The emphasize is on modifications that these generalizations impose on deficit angle which determine the total geometrical structure of the solutions, hence, physical/gravitational properties. It will be shown that depending on the background spacetime [being anti de Sitter (AdS) or de Sitter (dS)], these generalizations present different effects and modify the total structure of the solutions differently.

Mixed-Timescale Per-Group Hybrid Precoding for Multiuser Massive MIMO Systems

NASA Astrophysics Data System (ADS)

Teng, Yinglei; Wei, Min; Liu, An; Lau, Vincent; Zhang, Yong

2018-05-01

Considering the expensive radio frequency (RF) chain, huge training overhead and feedback burden issues in massive MIMO, in this letter, we propose a mixed-timescale per-group hybrid precoding (MPHP) scheme under an adaptive partially-connected RF precoding structure (PRPS), where the RF precoder is implemented using an adaptive connection network (ACN) and M analog phase shifters (APSs), where M is the number of antennas at the base station (BS). Exploiting the mixed-time stage channel state information (CSI) structure, the joint-design of ACN and APSs is formulated as a statistical signal-to-leakage-and-noise ratio (SSLNR) maximization problem, and a heuristic group RF precoding (GRFP) algorithm is proposed to provide a near-optimal solution. Simulation results show that the proposed design advances at better energy efficiency (EE) and lower hardware cost, CSI signaling overhead and computational complexity than the conventional hybrid precoding (HP) schemes.

Particle motion around magnetized black holes: Preston-Poisson space-time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Konoplya, R. A.

We analyze the motion of massless and massive particles around black holes immersed in an asymptotically uniform magnetic field and surrounded by some mechanical structure, which provides the magnetic field. The space-time is described by the Preston-Poisson metric, which is the generalization of the well-known Ernst metric with a new parameter, tidal force, characterizing the surrounding structure. The Hamilton-Jacobi equations allow the separation of variables in the equatorial plane. The presence of a tidal force from the surroundings considerably changes the parameters of the test particle motion: it increases the radius of circular orbits of particles and increases the bindingmore » energy of massive particles going from a given circular orbit to the innermost stable orbit near the black hole. In addition, it increases the distance of the minimal approach, time delay, and bending angle for a ray of light propagating near the black hole.« less

Effects of stellar evolution and ionizing radiation on the environments of massive stars

NASA Astrophysics Data System (ADS)

Mackey, J.; Langer, N.; Mohamed, S.; Gvaramadze, V. V.; Neilson, H. R.; Meyer, D. M.-A.

2014-09-01

We discuss two important effects for the astrospheres of runaway stars: the propagation of ionizing photons far beyond the astropause, and the rapid evolution of massive stars (and their winds) near the end of their lives. Hot stars emit ionizing photons with associated photoheating that has a significant dynamical effect on their surroundings. 3-D simulations show that H ii regions around runaway O stars drive expanding conical shells and leave underdense wakes in the medium they pass through. For late O stars this feedback to the interstellar medium is more important than that from stellar winds. Late in life, O stars evolve to cool red supergiants more rapidly than their environment can react, producing transient circumstellar structures such as double bow shocks. This provides an explanation for the bow shock and linear bar-shaped structure observed around Betelgeuse.

Computational mechanics analysis tools for parallel-vector supercomputers

NASA Technical Reports Server (NTRS)

Storaasli, O. O.; Nguyen, D. T.; Baddourah, M. A.; Qin, J.

1993-01-01

Computational algorithms for structural analysis on parallel-vector supercomputers are reviewed. These parallel algorithms, developed by the authors, are for the assembly of structural equations, 'out-of-core' strategies for linear equation solution, massively distributed-memory equation solution, unsymmetric equation solution, general eigen-solution, geometrically nonlinear finite element analysis, design sensitivity analysis for structural dynamics, optimization algorithm and domain decomposition. The source code for many of these algorithms is available from NASA Langley.

Benchmark Design and Installation: A synthesis of Existing Information.

DTIC Science & Technology

1987-07-01

casings (15 ft deep) drilled to rock and filled with concrete. Disks - 1 . Set on vertically stable structures (e.g., dam monoliths). 2 . Set in rock ...Structural movement survey 1 . Rock outcrops (first choice) -- chiseled square on high point. 2 . Massive concrete structure (second choice) - cut square on...bolt marker (type 2 ). 58,. % %--"% %I 1 ± 4 -I,.- Table Cl. Recomnded benchmarks. Type of condition or terrain Type of markert Bedrock, rock outcrops

Formation of massive, dense cores by cloud-cloud collisions

NASA Astrophysics Data System (ADS)

Takahira, Ken; Shima, Kazuhiro; Habe, Asao; Tasker, Elizabeth J.

2018-03-01

We performed sub-parsec (˜ 0.014 pc) scale simulations of cloud-cloud collisions of two idealized turbulent molecular clouds (MCs) with different masses in the range of (0.76-2.67) × 104 M_{⊙} and with collision speeds of 5-30 km s-1. Those parameters are larger than in Takahira, Tasker, and Habe (2014, ApJ, 792, 63), in which study the colliding system showed a partial gaseous arc morphology that supports the NANTEN observations of objects indicated to be colliding MCs using numerical simulations. Gas clumps with density greater than 10-20 g cm-3 were identified as pre-stellar cores and tracked through the simulation to investigate the effects of the mass of colliding clouds and the collision speeds on the resulting core population. Our results demonstrate that the smaller cloud property is more important for the results of cloud-cloud collisions. The mass function of formed cores can be approximated by a power-law relation with an index γ = -1.6 in slower cloud-cloud collisions (v ˜ 5 km s-1), and is in good agreement with observation of MCs. A faster relative speed increases the number of cores formed in the early stage of collisions and shortens the gas accretion phase of cores in the shocked region, leading to the suppression of core growth. The bending point appears in the high-mass part of the core mass function and the bending point mass decreases with increase in collision speed for the same combination of colliding clouds. The higher-mass part of the core mass function than the bending point mass can be approximated by a power law with γ = -2-3 that is similar to the power index of the massive part of the observed stellar initial mass function. We discuss implications of our results for the massive-star formation in our Galaxy.

Formation of massive, dense cores by cloud-cloud collisions

NASA Astrophysics Data System (ADS)

Takahira, Ken; Shima, Kazuhiro; Habe, Asao; Tasker, Elizabeth J.

2018-05-01

We performed sub-parsec (˜ 0.014 pc) scale simulations of cloud-cloud collisions of two idealized turbulent molecular clouds (MCs) with different masses in the range of (0.76-2.67) × 104 M_{⊙} and with collision speeds of 5-30 km s-1. Those parameters are larger than in Takahira, Tasker, and Habe (2014, ApJ, 792, 63), in which study the colliding system showed a partial gaseous arc morphology that supports the NANTEN observations of objects indicated to be colliding MCs using numerical simulations. Gas clumps with density greater than 10-20 g cm-3 were identified as pre-stellar cores and tracked through the simulation to investigate the effects of the mass of colliding clouds and the collision speeds on the resulting core population. Our results demonstrate that the smaller cloud property is more important for the results of cloud-cloud collisions. The mass function of formed cores can be approximated by a power-law relation with an index γ = -1.6 in slower cloud-cloud collisions (v ˜ 5 km s-1), and is in good agreement with observation of MCs. A faster relative speed increases the number of cores formed in the early stage of collisions and shortens the gas accretion phase of cores in the shocked region, leading to the suppression of core growth. The bending point appears in the high-mass part of the core mass function and the bending point mass decreases with increase in collision speed for the same combination of colliding clouds. The higher-mass part of the core mass function than the bending point mass can be approximated by a power law with γ = -2-3 that is similar to the power index of the massive part of the observed stellar initial mass function. We discuss implications of our results for the massive-star formation in our Galaxy.

The Structure of Massive Quiescent Galaxies at Z ~ 3 in the CANDELS-COSMOS Field

NASA Astrophysics Data System (ADS)

Fan, Lulu; Fang, Guanwen; Chen, Yang; Pan, Zhizheng; Lv, Xuanyi; Li, Jinrong; Lin, Lin; Kong, Xu

2013-07-01

In this Letter, we use a two-color (J - L) versus (V - J) selection criterion to search massive quiescent galaxy (QG) candidates at 2.5 <= z <= 4.0 in the CANDELS-COSMOS field. We construct an H F160W-selected catalog and complement it with public auxiliary data. We finally obtain 19 passive VJL-selected (hereafter pVJL) galaxies as the possible massive QG candidates at z ~ 3 by several constrains. We find the sizes of our pVJL galaxies are on average three to four times smaller than those of local early-type galaxies (ETGs) with analogous stellar mass. The compact size of these z ~ 3 galaxies can be modeled by assuming their formation at z form ~ 4-6 according to the dissipative collapse of baryons. Up to z < 4, the mass-normalized size evolution can be described by re vprop(1 + z)-1.0. Low Sérsic index and axis ratio, with median values n ~1.5 and b/a ~ 0.65, respectively, indicate that most of the pVJL galaxies are disk-dominated. Despite large uncertainty, the inner region of the median mass profile of our pVJL galaxies is similar to those of QGs at 0.5 < z < 2.5 and local ETGs. It indicates that local massive ETGs have been formed according to an inside-out scenario: the compact galaxies at high redshift make up the cores of local massive ETGs and then build up the outskirts according to dissipationless minor mergers.

Formation of the First Star Clusters and Massive Star Binaries by Fragmentation of Filamentary Primordial Gas Clouds

NASA Astrophysics Data System (ADS)

Hirano, Shingo; Yoshida, Naoki; Sakurai, Yuya; Fujii, Michiko S.

2018-03-01

We perform a set of cosmological simulations of early structure formation incorporating baryonic streaming motions. We present a case where a significantly elongated gas cloud with ∼104 solar mass (M ⊙) is formed in a pre-galactic (∼107 M ⊙) dark halo. The gas streaming into the halo compresses and heats the massive filamentary cloud to a temperature of ∼10,000 Kelvin. The gas cloud cools rapidly by atomic hydrogen cooling, and then by molecular hydrogen cooling down to ∼400 Kelvin. The rapid decrease of the temperature and hence of the Jeans mass triggers fragmentation of the filament to yield multiple gas clumps with a few hundred solar masses. We estimate the mass of the primordial star formed in each fragment by adopting an analytic model based on a large set of radiation hydrodynamics simulations of protostellar evolution. The resulting stellar masses are in the range of ∼50–120 M ⊙. The massive stars gravitationally attract each other and form a compact star cluster. We follow the dynamics of the star cluster using a hybrid N-body simulation. We show that massive star binaries are formed in a few million years through multi-body interactions at the cluster center. The eventual formation of the remnant black holes will leave a massive black hole binary, which can be a progenitor of strong gravitational wave sources similar to those recently detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO).

Preliminary interpretation of high resolution 3D seismic data from offshore Mt. Etna, Italy

NASA Astrophysics Data System (ADS)

Gross, F.; Krastel, S.; Chiocci, F. L.; Ridente, D.; Cukur, D.; Bialas, J.; Papenberg, C. A.; Crutchley, G.; Koch, S.

2013-12-01

In order to gain knowledge about subsurface structures and its correlation to seafloor expressions, a hydro-acoustic dataset was collected during RV Meteor Cruise M86/2 (December 2011/January 2012) in Messina Straits and offshore Mt. Etna. Especially offshore Mt. Etna, the data reveals an obvious connection between subsurface structures and previously known morphological features at the sea floor. Therefore a high resolution 3D seismic dataset was acquired between Riposto Ridge and Catania Canyon close to the shore of eastern Sicily. The study area is characterized by a major structural high, which hosts several ridge-like features at the seafloor. These features are connected to a SW-NE trending fault system. The ridges are bended in their NE-SW direction and host major escarpments at the seafloor. Furthermore they are located directly next to a massive amphitheater structure offshore Mt. Etna with slope gradients of up to 35°, which is interpreted as remnants of a massive submarine mass wasting event off Sicily. The new 3D seismic dataset allows an in depth analysis of the ongoing deformation of the east flank of Mt. Etna.

Geology of the Copper King Mine area, Prairie Divide, Larimer County, Colorado (Part 1)

USGS Publications Warehouse

Sims, Paul Kibler; Phair, George

1952-01-01

The Copper King mine, in Larimer County, Colo., in the northern part of the Front Range of Colorado, was operated for a short time prior to World War II for copper and zino, but since 1949, when pitchblende was discovered on the mine dump, it has been worked for uranium. The bedrock in the mine area consists predominantly of pre-Cambrian (Silver Plums) granite with minor migmatite and metasediments--biotite-quartz-plagioclase gneiss, biotite schist, quartzite, amphibolite, amphibole skarn, and biotite skols. The metasediments occur as inclusions that trend northeast in the granite. This trend is essentially parallel to the prevailing foliation in the granite. At places the metasediments are crosscut sharply by the granite to form angular, partly discordant, steep-walled bodies in the granite. Faults, confined to a narrow zone that extends through the mine, cut both the pre-Cambrian rocks and the contained sulfide deposits. The Copper King fault, a breccia zone, contains a deposit of pitchblende; the other faults are believed to be later than the ore. The two types of mineral deposits--massive sulfide and pitchblende deposits--in the mine area, are of widely different mineralogy, age, and origin. The massive sulfide deposits are small and consist of pyrite, sphalerite, chalcopyrite, pyrrhotite, and in places magnetite in amphibole skarn, mice skols, and quartzite. The deposit at the Copper King mine has yielded small quantities of high-grade sphalerite ore. The massive sulfides are pyrometasomatic deposits of pre-Cambrian age. The pitchblende at the Copper King mine is principally in the Copper King vein, a tight, hard breccia zone that cuts through both granite and the massive sulfide deposit. A small part of the pitchblende is in small fractures near the vein and in boxwork pyrite adjacent to the vein; the post-ore faults, close to their intersection with the Copper King vein, contain some radioactive material, but elsewhere, so far as is known, they are barren. The pitchblende in the deposit forms a steeply plunging ore shoot that has a horizontal length of more than 50 feet and a vertical height of about 85 feet. The thickness of the ore shoot averages about 2 feet, but it ranges from a feather edge to about 4 feet. The hard pitch-blende is intimately intergrown with siderite; other gangue minerals include pyrite, quartz, and finely comminuted fragments of the wall rocks. The vein was repeatedly reopened during mineral deposition as shown by several stages of brecciation and recommended by the vein matter. The pitchblende deposit probably formed at intermediate temperatures and depths and, according to the Pb/U ratio, is about 60 million years old--an early Tertiary age.

Evolution of the cosmic web

NASA Astrophysics Data System (ADS)

Cautun, Marius; van de Weygaert, Rien; Jones, Bernard J. T.; Frenk, Carlos S.

2014-07-01

The cosmic web is the largest scale manifestation of the anisotropic gravitational collapse of matter. It represents the transitional stage between linear and non-linear structures and contains easily accessible information about the early phases of structure formation processes. Here we investigate the characteristics and the time evolution of morphological components. Our analysis involves the application of the NEXUS Multiscale Morphology Filter technique, predominantly its NEXUS+ version, to high resolution and large volume cosmological simulations. We quantify the cosmic web components in terms of their mass and volume content, their density distribution and halo populations. We employ new analysis techniques to determine the spatial extent of filaments and sheets, like their total length and local width. This analysis identifies clusters and filaments as the most prominent components of the web. In contrast, while voids and sheets take most of the volume, they correspond to underdense environments and are devoid of group-sized and more massive haloes. At early times the cosmos is dominated by tenuous filaments and sheets, which, during subsequent evolution, merge together, such that the present-day web is dominated by fewer, but much more massive, structures. The analysis of the mass transport between environments clearly shows how matter flows from voids into walls, and then via filaments into cluster regions, which form the nodes of the cosmic web. We also study the properties of individual filamentary branches, to find long, almost straight, filaments extending to distances larger than 100 h-1 Mpc. These constitute the bridges between massive clusters, which seem to form along approximatively straight lines.

Conceptual design of new metrology laboratories for the National Physical Laboratory, United Kingdom

NASA Astrophysics Data System (ADS)

Manning, Christopher J.

1994-10-01

The National Physical Laboratory is planning to house the Division of Mechanical and Optical Metrology and the Division of Material Metrology in a new purpose built laboratory building on its site at Teddington, London, England. The scientific staff were involved in identifying and agreeing the vibration performance requirements of the conceptual design. This was complemented by an extensive surgery of vibration levels within the existing facilities and ambient vibration studies at the proposed site. At one end of the site there is significant vibration input from road traffic. Some of the test equipment is also in itself a source of vibration input. These factors, together with normal occupancy inputs, footfalls and door slams, and a highly serviced building led to vibration being dominant in influencing the structural form. The resulting structural concept comprises three separate structural elements for vibration and geotechnical reasons. The laboratories most sensitive to disturbance by vibration are located at the end of the site farthest from local roads on a massive ground bearing slab. Less sensitive laboratories and those containing vibration sources are located on a massive slab in deep, piled foundations. A common central plant area is located alongside on its own massive slab. Medium sensitivity laboratories and offices are located at first floor level on a reinforced concrete suspended floor of maximum stiffness per unit mass. The whole design has been such as to permit upgrading of areas, eg office to laboratory; laboratory to `high sensitivity' laboratory, to cater for changes in future use of the building.

Massively Parallel Simulations of Diffusion in Dense Polymeric Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faulon, Jean-Loup, Wilcox, R.T.

1997-11-01

An original computational technique to generate close-to-equilibrium dense polymeric structures is proposed. Diffusion of small gases are studied on the equilibrated structures using massively parallel molecular dynamics simulations running on the Intel Teraflops (9216 Pentium Pro processors) and Intel Paragon(1840 processors). Compared to the current state-of-the-art equilibration methods this new technique appears to be faster by some orders of magnitude.The main advantage of the technique is that one can circumvent the bottlenecks in configuration space that inhibit relaxation in molecular dynamics simulations. The technique is based on the fact that tetravalent atoms (such as carbon and silicon) fit in themore » center of a regular tetrahedron and that regular tetrahedrons can be used to mesh the three-dimensional space. Thus, the problem of polymer equilibration described by continuous equations in molecular dynamics is reduced to a discrete problem where solutions are approximated by simple algorithms. Practical modeling applications include the constructing of butyl rubber and ethylene-propylene-dimer-monomer (EPDM) models for oxygen and water diffusion calculations. Butyl and EPDM are used in O-ring systems and serve as sealing joints in many manufactured objects. Diffusion coefficients of small gases have been measured experimentally on both polymeric systems, and in general the diffusion coefficients in EPDM are an order of magnitude larger than in butyl. In order to better understand the diffusion phenomena, 10, 000 atoms models were generated and equilibrated for butyl and EPDM. The models were submitted to a massively parallel molecular dynamics simulation to monitor the trajectories of the diffusing species.« less

Reconstructing the anterior part of the nervous system of Gordius aquaticus (Nematomorpha, cycloneuralia) by a multimethodological approach.

PubMed

Henne, Stephan; Friedrich, Frank; Hammel, Jörg U; Sombke, Andy; Schmidt-Rhaesa, Andreas

2017-01-01

The Nematomorpha (horsehair worms) and Nematoda (round worms) are sister taxa (together Nematoida) and closely related to Scalidophora (Priapulida, Kinorhyncha, Loricifera). To date, all species were assumed to possess a specific brain type, i.e., the "cycloneuralian" brain that forms a ring-shaped neuropil around the pharynx and is composed of anteriorly and posteriorly located somata. However, descriptions of the nematomorph nervous system are rare and somewhat variable, calling in to question the validity of the cycloneuralian condition. To clarify whether there is a typical cycloneuralian pattern in the nematomorph brain, we investigated the anterior end of Gordius aquaticus with different methods: histology, immunohistochemistry and micro-CT analysis. Three-dimensional reconstructions were made from histological serial sections. The brain is composed of a central neuropil and a ring-shaped structure with associated somata. The unpaired ventral nerve cord emerges from the posteroventral part of the brain. A pharynx/esophagus is absent. In addition to the brain, a peripheral nerve plexus was detected. In summary, we interpret the architecture of the brain as potentially derived from a cycloneuralian structure, but being highly modified. The central position of the neuropil is possibly a consequence of the reduction of the anterior intestinal system as a result of the parasitic lifestyle. The ring-shaped arrangement of the somata may be a remnant of a cycloneuralian arrangement, after the two rings of somata (= cycloneuralian condition) either fused or one ring was reduced to form one massive ring-shaped structure in G. aquaticus. J. Morphol. 278:106-118, 2017. ©© 2016 Wiley Periodicals,Inc. © 2016 Wiley Periodicals, Inc.

Cosmic Spider is Good Mother

NASA Astrophysics Data System (ADS)

2006-04-01

Hanging above the Large Magellanic Cloud (LMC) - one of our closest galaxies - in what some describe as a frightening sight, the Tarantula nebula is worth looking at in detail. Also designated 30 Doradus or NGC 2070, the nebula owes its name to the arrangement of its brightest patches of nebulosity that somewhat resemble the legs of a spider. This name, of the biggest spiders on Earth, is also very fitting in view of the gigantic proportions of the celestial nebula - it measures nearly 1,000 light years across! ESO PR Photo 11/06 ESO PR Photo 13b/06 Tarantula's Central Cluster, R136 The Tarantula nebula is the largest emission nebula in the sky and also one of the largest known star-forming regions in all the Milky Way's neighbouring galaxies. Located about 170,000 light-years away, in the southern constellation Dorado (The Swordfish), it can be seen with the unaided eye. As shown in this image obtained with the FORS1 multi-mode instrument on ESO's Very Large Telescope, its structure is fascinatingly complex, with a large number of bright arcs and apparently dark areas in between. Inside the giant emission nebula lies a cluster of young, massive and hot stars, denoted R 136, whose intense radiation and strong winds make the nebula glow, shaping it into the form of a giant arachnid. The cluster is about 2 to 3 million years old, that is, almost from 'yesterday' in the 13.7 billion year history of the Universe. Several of the brighter members in the immediate surroundings of the dense cluster are among the most massive stars known, with masses well above 50 times the mass of our Sun. The cluster itself contains more than 200 massive stars. ESO PR Photo 11/06 ESO PR Photo 13c/06 The Stellar Cluster Hodge 301 In the upper right of the image, another cluster of bright, massive stars is seen. Known to astronomers as Hodge 301, it is about 20 million years old, or about 10 times older than R136. The more massive stars of Hodge 301 have therefore already exploded as supernovae, blasting material away at tremendous speed and creating a web of entangled filaments. More explosions will come soon - in astronomical terms - as three red supergiants are indeed present in Hodge 301 that will end their life in the gigantic firework of a supernova within the next million years. ESO PR Photo 13d/06 ESO PR Photo 13d/06 Gas Pillars in Tarantula Nebula While some stars are dying in this spidery cosmic inferno, others are yet to be born. Some structures, seen in the lower part of the image, have the appearance of elephant trunks, not unlike the famous and fertile "Pillars of Creation" at the top of which stars are forming. In fact, it seems that stars form all over the place in this gigantic stellar nursery and in all possible masses, at least down to the mass of our Sun. In some places, in a marvellous recycling process, it is the extreme radiation from the hot and massive stars and the shocks created by the supernova explosions that has compressed the gas to such extent to allow stars to form. To the right and slightly below the central cluster, a red bubble is visible. The star that blows the material making this bubble is thought to be 20 times more massive, 130 000 times more luminous, 10 times larger and 6 times hotter than our Sun. A possible fainter example of such a bubble is also visible just above the large red bubble in the image. ESO PR Photo 13e/06 ESO PR Photo 13e/06 Red Bubbles in Tarantula Nebula Earlier colour composite images of the Tarantula nebula have been made with other instruments and/or filters at ESO's telescopes, e.g. PR Photo 05a/00 in visual light with FORS2 at the VLT at Paranal, and PR Photos 14a-g/02 and 34a-h/04 with the Wide-Field Imager at the ESO/MPG 2.2-m telescope at La Silla.

Surface wave tomography of the Ontong Java Plateau: Seismic probing of the largest igneous province

NASA Astrophysics Data System (ADS)

Richardson, William Philip

1998-12-01

Large igneous provinces (LIP), such as the gigantic Cretaceous oceanic plateaus, the Ontong-Java, the Manihiki and the Kerguelen, are part of a globally distributed diverse suite of massive crustal features considered to be episodic representations of mantle dynamics (Coffin and Eldholm, 1994). The Ontong Java Plateau in the central western Pacific is by far the largest (and presumably thickest) of these provinces and is believed to have been emplaced rapidly in the Aptian, ˜122 Ma (Tarduno et al., 1991). From 1994 to 1996 four PASSCAL broadband seismic stations were deployed in an array north of the OJP. Analysis was conducted on vertical component broadband seismograms from events recorded on the Micronesian Seismic Experiment array between January 1994 and March 1996. The purpose of this experiment is to investigate the crustal and upper mantle structure of the Ontong Java Plateau (OJP) employing surface wave tomographic methods. Using the partitioned waveform inversion method (Nolet, 1990) and earthquakes with published Centroid Moment Tensor (Dziewonski et al., 1981) solutions, we produce waveform fits from source-to-receiver paths that primarily sample the OJP. From these waveform fits, linearized constraints on shear velocity suggest: (1) a massively thickened crust over the center of the OJP-greater than 35km over central areas of the plateau while thinning off-center; (2) a pronounced low-velocity zone down to ˜300km depth-a robust result in agreement with recent geochemical predictions (Neal et al., 1997); (3) the probability of lateral heterogeneity across the OJP. Finally, by combining many single waveform inversions (van der Lee and Nolet, 1997b) a 3-D shear velocity model can be computed for the Ontong Java Plateau and the nearby Caroline Basin. New constraints on the crustal thickness (and hence the volume extruded) are presented, thereby adding to the understanding of the overall tectonic setting and possible emplacement mechanism of the structure.

Optical Symbolic Computing

NASA Astrophysics Data System (ADS)

Neff, John A.

1989-12-01

Experiments originating from Gestalt psychology have shown that representing information in a symbolic form provides a more effective means to understanding. Computer scientists have been struggling for the last two decades to determine how best to create, manipulate, and store collections of symbolic structures. In the past, much of this struggling led to software innovations because that was the path of least resistance. For example, the development of heuristics for organizing the searching through knowledge bases was much less expensive than building massively parallel machines that could search in parallel. That is now beginning to change with the emergence of parallel architectures which are showing the potential for handling symbolic structures. This paper will review the relationships between symbolic computing and parallel computing architectures, and will identify opportunities for optics to significantly impact the performance of such computing machines. Although neural networks are an exciting subset of massively parallel computing structures, this paper will not touch on this area since it is receiving a great deal of attention in the literature. That is, the concepts presented herein do not consider the distributed representation of knowledge.

Platelet-rich plasma for arthroscopic repair of large to massive rotator cuff tears: a randomized, single-blind, parallel-group trial.

PubMed

Jo, Chris Hyunchul; Shin, Ji Sun; Lee, Young Gil; Shin, Won Hyoung; Kim, Hyang; Lee, Seung Yeon; Yoon, Kang Sup; Shin, Sue

2013-10-01

Platelet-rich plasma (PRP) is expected to have a biological augmentation potential in the healing of various diseases and injuries, including rotator cuff tears. However, few evaluations have been performed specifically for large to massive tears. To assess the efficacy of PRP augmentation in patients undergoing arthroscopic repair for large to massive rotator cuff tears. Randomized controlled trial; Level of evidence, 1. A total of 48 patients scheduled for arthroscopic repair of large to massive rotator cuff tears were randomly assigned to receive either PRP-augmented (PRP group) or conventional treatment (conventional group). In the PRP group, 3 PRP gels (3 × 3 mL) were applied to each patient between the torn end and the greater tuberosity. The primary outcome measure was the retear rate assessed by magnetic resonance imaging (MRI) or computed tomographic arthrography (CTA) at a minimum of 9 months after surgery. Secondary outcome measures included pain, range of motion, muscle strength, overall satisfaction, functional scores, and the change in cross-sectional area (CSA) of the supraspinatus. The retear rate of the PRP group (20.0%) was significantly lower than that of the conventional group (55.6%) (P = .023). Clinical outcomes showed no statistical difference between the 2 groups (all P > .05) except for the overall function (P = .043). The change in 1-year postoperative and immediately postoperative CSA was significantly different between the 2 groups: -15.54 ± 94.34 mm² in the PRP group versus -85.62 ± 103.57 mm² in the conventional group (P = .047). The application of PRP for large to massive rotator cuff repairs significantly improved structural outcomes, as evidenced by a decreased retear rate and increased CSA of the supraspinatus compared with repairs without PRP augmentation. While there was no significant difference in clinical outcomes except the overall shoulder function after 1-year follow-up, better structural outcomes in the PRP group might suggest improved clinical outcomes at longer term follow-up.

Arthroscopic repair of massive contracted rotator cuff tears: aggressive release with anterior and posterior interval slides do not improve cuff healing and integrity.

PubMed

Kim, Sung-Jae; Kim, Sung-Hwan; Lee, Su-Keon; Seo, Jae-Wan; Chun, Yong-Min

2013-08-21

Few studies of large-to-massive contracted rotator cuff tears have examined the arthroscopic complete repair obtained by a posterior interval slide and whether the clinical outcomes or structural integrity achieved are better than those after partial repair without the posterior interval slide. The study included forty-one patients with large-to-massive contracted rotator cuff tears, not amenable to complete repair with margin convergence alone. The patients underwent either arthroscopic complete repair with a posterior interval slide and side-to-side repair of the interval slide edge (twenty-two patients; Group P) or partial repair with margin convergence (nineteen patients; Group M). The patient assignment was not randomized. The Simple Shoulder Test (SST), American Shoulder and Elbow Surgeons (ASES) score, University of California at Los Angeles (UCLA) shoulder score, and range of motion were used to compare the functional outcomes. Preoperative and six-month postoperative magnetic resonance arthrography (MRA) images were compared within or between groups. At the two-year follow-up evaluation, the SST, ASES score, UCLA score, and range of motion had significantly improved (p < 0.001 for all) in both groups. However, no significant differences were detected between groups. Even though the difference in preoperative tear size on MRA images was not significant, follow-up MRA images identified a retear in twenty patients (91%) in Group P and a significant difference in tear size between groups (p = 0.007). The complete repair group with an aggressive release had no better clinical or structural outcomes compared with the partial repair group with margin convergence alone for large-to-massive contracted rotator cuff tears. In addition, the complete repair group had a 91% retear rate and a greater defect on follow-up MRA images. Even though this study had a relatively short-term follow-up, a complete repair of large-to-massive contracted rotator cuff tears, with an aggressive release such as posterior interval slide, may not have an increased benefit compared with partial repair without posterior interval slide.

Reconstructing gravitational wave source parameters via direct comparisons to numerical relativity I: Method

NASA Astrophysics Data System (ADS)

Lange, Jacob; O'Shaughnessy, Richard; Healy, James; Lousto, Carlos; Shoemaker, Deirdre; Lovelace, Geoffrey; Scheel, Mark; Ossokine, Serguei

2016-03-01

In this talk, we describe a procedure to reconstruct the parameters of sufficiently massive coalescing compact binaries via direct comparison with numerical relativity simulations. For sufficiently massive sources, existing numerical relativity simulations are long enough to cover the observationally accessible part of the signal. Due to the signal's brevity, the posterior parameter distribution it implies is broad, simple, and easily reconstructed from information gained by comparing to only the sparse sample of existing numerical relativity simulations. We describe how followup simulations can corroborate and improve our understanding of a detected source. Since our method can include all physics provided by full numerical relativity simulations of coalescing binaries, it provides a valuable complement to alternative techniques which employ approximations to reconstruct source parameters. Supported by NSF Grant PHY-1505629.

Line profile variability in the massive binary HD 152219

NASA Astrophysics Data System (ADS)

Sana, H.; Gosset, E.

2009-07-01

HD 152219 is a massive binary system with O9.5 III and B1-2 III/V components and a short orbital period of 4.2 d. In a previous work, we showed that the primary star (M_{prim}˜21 M_⊙) was presenting clear line profile variabilities (LPVs) that might be caused by nonradial pulsations (NRPs). In the present work, we report on an intensive spectroscopic monitoring, that aimed at unveiling the nature of the detected LPVs. Based on this new data set, we discard the NRPs and point out the Rossiter-McLaughlin effect as % being the cause of the observed LPVs. The upper limit derived on the amplitude of undetected NRPs, if any, is set at a couple of part per thousands of the continuum level.

Evolutionary helium and CNO anomalies in the atmospheres and winds of massive hot stars

NASA Technical Reports Server (NTRS)

Walborn, Nolan R.

1987-01-01

The ubiquitous evidence for processed materials in the atmospheres, winds, and circumstellar ejecta of massive stars is reviewed. A broad array of normal and peculiar evolutionary stages is considered, up to and including Type II supernova progenitors. The quantitative analysis of these spectra is difficult, and until recently for the most part only qualitative or approximate results have been available. However, several important current programs promise reliable abundance calculations. A significant emerging result is that the morphologically normal majority of both hot and cold supergiants may already display an admixture of CNO-cycle products in their atmospheres. It may become possible in this way to identify blue supergiants returning from the red supergiant region, as appears to have been the case for the SN 1987A progenitor.

The portals 4.0.1 network programming interface.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrett, Brian W.; Brightwell, Ronald Brian; Pedretti, Kevin

2013-04-01

This report presents a specification for the Portals 4.0 network programming interface. Portals 4.0 is intended to allow scalable, high-performance network communication between nodes of a parallel computing system. Portals 4.0 is well suited to massively parallel processing and embedded systems. Portals 4.0 represents an adaption of the data movement layer developed for massively parallel processing platforms, such as the 4500-node Intel TeraFLOPS machine. Sandias Cplant cluster project motivated the development of Version 3.0, which was later extended to Version 3.3 as part of the Cray Red Storm machine and XT line. Version 4.0 is targeted to the next generationmore » of machines employing advanced network interface architectures that support enhanced offload capabilities. 3« less

Applications of massively parallel computers in telemetry processing

NASA Technical Reports Server (NTRS)

El-Ghazawi, Tarek A.; Pritchard, Jim; Knoble, Gordon

1994-01-01

Telemetry processing refers to the reconstruction of full resolution raw instrumentation data with artifacts, of space and ground recording and transmission, removed. Being the first processing phase of satellite data, this process is also referred to as level-zero processing. This study is aimed at investigating the use of massively parallel computing technology in providing level-zero processing to spaceflights that adhere to the recommendations of the Consultative Committee on Space Data Systems (CCSDS). The workload characteristics, of level-zero processing, are used to identify processing requirements in high-performance computing systems. An example of level-zero functions on a SIMD MPP, such as the MasPar, is discussed. The requirements in this paper are based in part on the Earth Observing System (EOS) Data and Operation System (EDOS).

The Human Constraint; The Coming Shortage of Managerial Talent.

ERIC Educational Resources Information Center

Miner, John B.

The prospect of a massive managerial talent shortage in the United States and what can be done about it are the central concerns of the study, which revealed a notable decline in motivation to manage among business students and young managers. Part 1 defines the components of motivation to manage and their vital relationship to personal and…

Causal Wave Propagation for Relativistic Massive Particles: Physical Asymptotics in Action

ERIC Educational Resources Information Center

Berry, M. V.

2012-01-01

Wavepackets representing relativistic quantum particles injected into a half-space, from a source that is switched on at a definite time, are represented by superpositions of plane waves that must include negative frequencies. Propagation is causal: it is a consequence of analyticity that at time t no part of the wave has travelled farther than…

Big Data: Laying the Groundwork. ECAR Working Group Paper

ERIC Educational Resources Information Center

Almes, Guy T.; Hillegas, Curtis W.; Lance, Timothy; Lynch, Clifford A.; Monaco, Gregory E.; Mundrane, Michael R.; Zottola, Ralph J.

2014-01-01

This paper is part of series of the EDUCAUSE Center for Analysis and Research Campus Cyberinfrastructure (ECAR-CCI) Working Group. The topic of big data continues to receive a great deal of publicity because of its promise for opening new avenues of scholarly discovery and commercial opportunity. The ability to sift rapidly through massive amounts…

Big Data in the Campus Landscape: Curation. ECAR Working Group Paper

ERIC Educational Resources Information Center

Lynch, Clifford A.

2015-01-01

This paper is part of series of the EDUCAUSE Center for Analysis and Research Campus Cyberinfrastructure (ECAR-CCI) Working Group. The topic of big data continues to receive a great deal of publicity because of its promise for opening new avenues of scholarly discovery and commercial opportunity. The ability to sift rapidly through massive amounts…

Geographies of Social Exclusion: Education Access in the Philippines

ERIC Educational Resources Information Center

Symaco, Lorraine Pe

2013-01-01

Despite the massive education sector of the country, the Philippines--being located in the Pacific Ring of Fire and the typhoon belt--is home to a number of natural instabilities that frequently disrupt the school calendar. Conflict areas in selected parts of the island of Mindanao and the remote geographic features of the country also pose…

Mount St. Helens: Still erupting lessons 31 years later

Treesearch

Rhonda Mazza; Charlie Crisafulli; Fred Swanson

2011-01-01

The massive volcanic eruption of Mount St. Helens 31 years ago provided the perfect backdrop for studying the earliest stages of forest development. Immediately after the eruption, some areas of the blast area were devoid of life. On other parts of the volcanic landscape, many species survived, although their numbers were greatly reduced. Reassembly began at many...

A View through a Bamboo Screen: From Moire Patterns to Black Holes.

ERIC Educational Resources Information Center

Oda, Minoru

1992-01-01

Describes the genesis, the early experiments, and the limitations of X-ray astronomy. Discusses original methods for searching and locating the first interstellar X-ray source, modern attempts to identify a massive black hole as part of a binary system X-ray source, and the effort to generate X-ray images of solar flares. (JJK)

Alliance for Workforce Skills. Final Report. Summative Evaluation Report.

ERIC Educational Resources Information Center

Capital Community-Technical Coll., Hartford, CT.

The Alliance for Workforce Skills (AWS), a public/private partnership, provided adult basic skills training to employed and unemployed men and women in the Greater Hartford area. Many goals were not met, due in large part to the massive downturn in the Hartford economy. Only one of the four sponsoring corporations was still an active AWS partner…

Modeling MOOC Student Behavior with Two-Layer Hidden Markov Models

ERIC Educational Resources Information Center

Geigle, Chase; Zhai, ChengXiang

2017-01-01

Massive open online courses (MOOCs) provide educators with an abundance of data describing how students interact with the platform, but this data is highly underutilized today. This is in part due to the lack of sophisticated tools to provide interpretable and actionable summaries of huge amounts of MOOC activity present in log data. To address…

Retirement Trends and Public Policy: The Carrot and the Stick.

ERIC Educational Resources Information Center

Quinn, Joseph F.; Burkhauser, Richard V.

Recent trends toward earlier retirement have exacerbated the financial problems facing the Social Security system and many other public and private pension plans. The massive commitment of public and private funds to Social Security and pension funds is partly responsible for the trend to early retirement. This, in fact, was one of the early goals…

School Improvements in Abu Dhabi, United Arab Emirates: Asking the "Expert Witnesses"

ERIC Educational Resources Information Center

Dickson, Martina

2013-01-01

Government schools in Abu Dhabi, as part of wide-scale educational reforms undertaken in the whole of the United Arab Emirates, have undergone massive school improvement developments over the past seven years. Over the course of these years, the reality of student life for those in government schools has been widely altered. This research explores…

Gaming as Extramural English L2 Learning and L2 Proficiency among Young Learners

ERIC Educational Resources Information Center

Sylven, Liss Kerstin; Sundqvist, Pia

2012-01-01

Today, playing digital games is an important part of many young people's everyday lives. Claims have been made that certain games, in particular massively multiplayer online role-playing games (MMORPGs) provide L2 English learners with a linguistically rich and cognitively challenging virtual environment that may be conducive to L2 learning, as…

Structural properties of atactic polystyrene adsorbed onto solid surfaces.

PubMed

Tatek, Yergou B; Tsige, Mesfin

2011-11-07

In the present work, we are studying the local conformation of chains in a thin film of polystyrene adsorbed on a solid substrate by using atomistically detailed simulations. The simulations are carried out by using the readily available and massively parallel molecular dynamics code known as LAMMPS. In particular, a special emphasis is given to the density and orientation of side chains (which consist of phenyl groups and methylene units) at solid/polymer and polymer/vacuum interfaces. Three types of substrates were used in our study: α-quartz, graphite, and amorphous silica. Our investigation was restricted to atactic polystyrene. Our results show that the density and structural properties of side chains depend on the type of surface. An excess of phenyl rings is observed near the α-quartz substrate while the film adsorbed on graphite is depleted in C(6)H(5). Moreover, the orientation of the rings and methylene units on the substrate/film interface show a strong dependence on the type of the substrate, while the rings at the film/vacuum interface show a marked tendency to point outward, away from the film. The results we obtained are in a large part in good agreement with previous experimental and simulation results.

Health monitoring for subway station structure by fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Zhou, Yao; Wang, Yuan-Feng; Han, Bing; Zhou, Zhi

2008-03-01

Fiber Bragg grating (FBG) sensors hold a great deal of potential for structural monitoring because of their high sensitivity and exceptional stability for long-term monitoring. FBG sensors have been applied to sense a number of physical measurands including strain, temperature, pressure etc. These applications are based on the same principle, i.e. the measurement of Bragg wavelength shift caused by the measurands. The characters and principle of FBG sensors have been introduced in detail. The relative experiment is done. The results show that FBG sensors have high sensitivity and long-term stability. It is feasible to use the sensors to the structural health monitoring (SHM). Cement hydration produces heat, which may provoke important temperature rises in massive structures. Such a high temperature may be a factor for cracking during the cooling phase. Thus, it is important to be able to calculate and control the heat to be produced by a given concrete at the mixture-proportioning stage. Theory of heat of hydration is also introduced in this paper. FBG sensors have been applied successfully in health monitoring for Guomao subway station structure. Compared with results measured by vibrating wire sensors and computed by finite element method, the monitoring results show temperature and strains can be accurately measured by FBG sensors. It is convenient to study on heat of hydration of massive concrete and guide structural design.

Rapidly rotating neutron stars with a massive scalar field—structure and universal relations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doneva, Daniela D.; Yazadjiev, Stoytcho S., E-mail: daniela.doneva@uni-tuebingen.de, E-mail: yazad@phys.uni-sofia.bg

We construct rapidly rotating neutron star models in scalar-tensor theories with a massive scalar field. The fact that the scalar field has nonzero mass leads to very interesting results since the allowed range of values of the coupling parameters is significantly broadened. Deviations from pure general relativity can be very large for values of the parameters that are in agreement with the observations. We found that the rapid rotation can magnify the differences several times compared to the static case. The universal relations between the normalized moment of inertia and quadrupole moment are also investigated both for the slowly andmore » rapidly rotating cases. The results show that these relations are still EOS independent up to a large extend and the deviations from pure general relativity can be large. This places the massive scalar-tensor theories amongst the few alternative theories of gravity that can be tested via the universal I -Love- Q relations.« less

Resolving Supercritical Orion Cores

NASA Astrophysics Data System (ADS)

Li, Di; Chapman, N.; Goldsmith, P.; Velusamy, T.

2009-01-01

The theoretical framework for high mass star formation (HMSF) is unclear. Observations reveal a seeming dichotomy between high- and low-mass star formation, with HMSF occurring only in Giant Molecular Clouds (GMC), mostly in clusters, and with higher star formation efficiencies than low-mass star formation. One crucial constraint to any theoretical model is the dynamical state of massive cores, in particular, whether a massive core is in supercritical collapse. Based on the mass-size relation of dust emission, we select likely unstable targets from a sample of massive cores (Li et al. 2007 ApJ 655, 351) in the nearest GMC, Orion. We have obtained N2H+ (1-0) maps using CARMA with resolution ( 2.5", 0.006 pc) significantly better than existing observations. We present observational and modeling results for ORI22. By revealing the dynamic structure down to Jeans scale, CARMA data confirms the dominance of gravity over turbulence in this cores. This work was performed by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Microorganisms Trapped Within Permafrost Ice In The Fox Permafrost Tunnel, Alaska

NASA Astrophysics Data System (ADS)

Katayama, T.; Tanaka, M.; Douglas, T. A.; Cai, Y.; Tomita, F.; Asano, K.; Fukuda, M.

2008-12-01

Several different types of massive ice are common in permafrost. Ice wedges are easily recognized by their shape and foliated structure. They grow syngenetically or epigenetically as a result of repeated cycles of frost cracking followed by the infiltration of snow, melt water, soil or other material into the open frost cracks. Material incorporated into ice wedges becomes frozen and preserved. Pool ice, another massive ice type, is formed by the freezing of water resting on top of frozen thermokarst sediment or melting wedges and is not foliated. The Fox Permafrost Tunnel in Fairbanks was excavated within the discontinuous permafrost zone of central Alaska and it contains permafrost, ice wedges, and pool ice preserved at roughly -3°C. We collected samples from five ice wedges and three pool ice structures in the Fox Permafrost Tunnel. If the microorganisms were incorporated into the ice during its formation, a community analysis of the microorganisms could elucidate the environment in which the ice was formed. Organic material from sediments in the tunnel was radiocarbon-dated between 14,000 and 30,000 years BP. However, it is still not clear when the ice wedges were formed or subsequently deformed because they are only partially exposed and their upper surfaces are above the tunnel walls. The objectives of our study were to determine the biogeochemical conditions during massive ice formation and to analyze the microbial community within the ices by incubation-based and DNA-based analyses. The geochemical profile and the PCR-DGGE band patterns of bacteria among five ice wedge and 3 portions of pool ice samples were markedly different. The DGGE band patterns of fungi were simple with a few bands of fungi or yeast. The dominant bands of ice wedge and pool ice samples were affiliated with the genus Geomyces and Doratomyces, respectively. Phylogenetic analysis using rRNA gene ITS regions indicated isolates of Geomyces spp. from different ice wedges were affiliated with different clusters. The enumeration of fungal colonies among the ice wedge and pool ice samples were also different. These results demonstrate that different massive ice structures had different microbial and geochemical environments or backgrounds when they were formed.

Development of FB-MultiPier dynamic vessel-collision analysis models, phase 2.

DOT National Transportation Integrated Search

2014-07-01

Massive waterway vessels such as barges regularly transit navigable waterways in the U.S. During passages that fall within : the vicinity of bridge structures, vessels may (under extreme circumstances) deviate from the intended vessel transit path. A...

Lunar Tectonic Triad Joining Both Hemispheres and Its Terrestrial Analogue

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

2018-06-01

"Orbits make structures" — This three word notion explains similarities of fundamental tectonic features of the small satellite and much larger massive Earth. Very impressive are geoids of two bodies — similarity of SPA Basin and Indian depressions.

An Effective Massive Sensor Network Data Access Scheme Based on Topology Control for the Internet of Things

PubMed Central

Yi, Meng; Chen, Qingkui; Xiong, Neal N.

2016-01-01

This paper considers the distributed access and control problem of massive wireless sensor networks’ data access center for the Internet of Things, which is an extension of wireless sensor networks and an element of its topology structure. In the context of the arrival of massive service access requests at a virtual data center, this paper designs a massive sensing data access and control mechanism to improve the access efficiency of service requests and makes full use of the available resources at the data access center for the Internet of things. Firstly, this paper proposes a synergistically distributed buffer access model, which separates the information of resource and location. Secondly, the paper divides the service access requests into multiple virtual groups based on their characteristics and locations using an optimized self-organizing feature map neural network. Furthermore, this paper designs an optimal scheduling algorithm of group migration based on the combination scheme between the artificial bee colony algorithm and chaos searching theory. Finally, the experimental results demonstrate that this mechanism outperforms the existing schemes in terms of enhancing the accessibility of service requests effectively, reducing network delay, and has higher load balancing capacity and higher resource utility rate. PMID:27827878

CSI in Supernova Remnants

NASA Astrophysics Data System (ADS)

Chu, You-Hua

2017-02-01

Supernovae (SNe) explode in environments that have been significantly modified by the SN progenitors. For core-collapse SNe, the massive progenitors ionize the ambient interstellar medium (ISM) via UV radiation and sweep the ambient ISM via fast stellar winds during the main sequence phase, replenish the surroundings with stellar material via slow winds during the luminous blue variable (LBV) or red supergiant (RSG) phase, and sweep up the circumstellar medium (CSM) via fast winds during the Wolf-Rayet (WR) phase. If a massive progenitor was in a close binary system, the binary interaction could have caused mass ejection in certain preferred directions, such as the orbital plane, and even bipolar outflow/jet. As a massive star finally explodes, the SN ejecta interacts first with the CSM that was ejected and shaped by the star itself. As the newly formed supernova remnant (SNR) expands further, it encounters interstellar structures that were shaped by the progenitor from earlier times. Therefore, the structure and evolution of a SNR is largely dependent on the initial mass and close binarity of the SN progenitor. The Large Magellanic Cloud (LMC) has an excellent sample of over 50 confirmed SNRs that are well resolved by Hubble Space Telescope, Chandra X-ray Observatory, and Spitzer Space Telescope. These multi-wavelength observations allow us to conduct stellar forensics in SNRs and understand the wide variety of morphologies and physical properties of SNRs observed.

Neutrinos in the holographic dark energy model: constraints from latest measurements of expansion history and growth of structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jing-Fei; Zhao, Ming-Ming; Li, Yun-He

The model of holographic dark energy (HDE) with massive neutrinos and/or dark radiation is investigated in detail. The background and perturbation evolutions in the HDE model are calculated. We employ the PPF approach to overcome the gravity instability difficulty (perturbation divergence of dark energy) led by the equation-of-state parameter w evolving across the phantom divide w=−1 in the HDE model with c<1. We thus derive the evolutions of density perturbations of various components and metric fluctuations in the HDE model. The impacts of massive neutrino and dark radiation on the CMB anisotropy power spectrum and the matter power spectrum inmore » the HDE scenario are discussed. Furthermore, we constrain the models of HDE with massive neutrinos and/or dark radiation by using the latest measurements of expansion history and growth of structure, including the Planck CMB temperature data, the baryon acoustic oscillation data, the JLA supernova data, the Hubble constant direct measurement, the cosmic shear data of weak lensing, the Planck CMB lensing data, and the redshift space distortions data. We find that ∑ m{sub ν}<0.186 eV (95% CL) and N{sub eff}=3.75{sup +0.28}{sub −0.32} in the HDE model from the constraints of these data.« less

Multifaceted free-space image distributor for optical interconnects in massively parrallel processing

NASA Astrophysics Data System (ADS)

Zhao, Feng; Frietman, Edward E. E.; Han, Zhong; Chen, Ray T.

1999-04-01

A characteristic feature of a conventional von Neumann computer is that computing power is delivered by a single processing unit. Although increasing the clock frequency improves the performance of the computer, the switching speed of the semiconductor devices and the finite speed at which electrical signals propagate along the bus set the boundaries. Architectures containing large numbers of nodes can solve this performance dilemma, with the comment that main obstacles in designing such systems are caused by difficulties to come up with solutions that guarantee efficient communications among the nodes. Exchanging data becomes really a bottleneck should al nodes be connected by a shared resource. Only optics, due to its inherent parallelism, could solve that bottleneck. Here, we explore a multi-faceted free space image distributor to be used in optical interconnects in massively parallel processing. In this paper, physical and optical models of the image distributor are focused on from diffraction theory of light wave to optical simulations. the general features and the performance of the image distributor are also described. The new structure of an image distributor and the simulations for it are discussed. From the digital simulation and experiment, it is found that the multi-faceted free space image distributing technique is quite suitable for free space optical interconnection in massively parallel processing and new structure of the multifaceted free space image distributor would perform better.

Geochemistry and chronology of the early Paleozoic diorites and granites in the Huangtupo volcanogenic massive sulfide (VMS) deposit, Eastern Tianshan, NW China: Implications for petrogenesis and geodynamic setting

NASA Astrophysics Data System (ADS)

Zheng, Jiahao; Chai, Fengmei; Feng, Wanyi; Yang, Fuquan; Shen, Ping

2018-03-01

The Eastern Tianshan orogen contains many late Paleozoic porphyry Cu and magmatic Cu-Ni deposits. Recent studies demonstrate that several early Paleozoic volcanogenic massive sulfide (VMS) Cu-polymetallic and porphyry Cu deposits were discovered in the northern part of Eastern Tianshan. This study presents zircon U-Pb, whole-rock geochemical, and Sr-Nd isotopic data for granites and diorites from the Huangtupo VMS Cu-Zn deposit, northern part of the Eastern Tianshan. Our results can provide constraints on the genesis of intermediate and felsic intrusions as well as early Paleozoic geodynamic setting of the northern part of Eastern Tianshan. LA-ICP-MS zircon U-Pb analyses suggest that the granites and diorites were formed at 435 ± 2 Ma and 440 ± 2 Ma, respectively. Geochemical characteristics suggest that the Huangtupo granites and diorites are metaluminous rocks, exhibiting typical subduction-related features such as enrichment in LILE and LREE and depletion in HFSE. The diorites have moderate Mg#, positive εNd(t) values (+6.4 to +7.3), and young Nd model ages, indicative of a depleted mantle origin. The granites exhibit mineral assemblages and geochemical characteristics of I-type granites, and they have positive εNd(t) values (+6.7 to +10.2) and young Nd model ages, suggesting a juvenile crust origin. The early Paleozoic VMS Cu-polymetallic and porphyry Cu deposits in the northern part of Eastern Tianshan were genetically related. The formation of the early Paleozoic magmatic rocks as well as VMS and porphyry Cu deposits in the northern part of Eastern Tianshan was due to a southward subduction of the Junggar oceanic plate.

Hubble Captures Massive Dead Disk Galaxy that Challenges Theories of Galaxy Evolution

NASA Image and Video Library

2017-12-08

By combining the power of a "natural lens" in space with the capability of NASA's Hubble Space Telescope, astronomers made a surprising discovery—the first example of a compact yet massive, fast-spinning, disk-shaped galaxy that stopped making stars only a few billion years after the big bang. Finding such a galaxy early in the history of the universe challenges the current understanding of how massive galaxies form and evolve, say researchers. Read more: go.nasa.gov/2sWwKkc caption: Acting as a “natural telescope” in space, the gravity of the extremely massive foreground galaxy cluster MACS J2129-0741 magnifies, brightens, and distorts the far-distant background galaxy MACS2129-1, shown in the top box. The middle box is a blown-up view of the gravitationally lensed galaxy. In the bottom box is a reconstructed image, based on modeling that shows what the galaxy would look like if the galaxy cluster were not present. The galaxy appears red because it is so distant that its light is shifted into the red part of the spectrum. Credits: NASA, ESA, M. Postman (STScI), and the CLASH team NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Massive Open Online Courses in Dental Education: Two Viewpoints: Viewpoint 1: Massive Open Online Courses Offer Transformative Technology for Dental Education and Viewpoint 2: Massive Open Online Courses Are Not Ready for Primetime.

PubMed

Kearney, Rachel C; Premaraj, Sundaralingam; Smith, Becky M; Olson, Gregory W; Williamson, Anne E; Romanos, Georgios

2016-02-01

This point/counterpoint article discusses the strengths and weaknesses of incorporating Massive Open Online Courses (MOOCs) into dental education, focusing on whether this relatively new educational modality could impact traditional dental curricula. Viewpoint 1 asserts that MOOCs can be useful in dental education because they offer an opportunity for students to learn through content and assessment that is delivered online. While specific research on MOOCs is limited, some evidence shows that online courses may produce similar learning outcomes to those in face-to-face courses. Given that MOOCs are intended to be open source, there could be opportunities for dental schools with faculty shortages and financial constraints to incorporate these courses into their curricula. In addition to saving money, dental schools could use MOOCs as revenue sources in areas such as continuing education. Viewpoint 2 argues that the hype over MOOCs is subsiding due in part to weaker than expected evidence about their value. Because direct contact between students, instructors, and patients is essential to the dental curriculum, MOOCs have yet to demonstrate their usefulness in replacing more than a subset of didactic courses. Additionally, learning professionalism, a key component of health professions education, is best supported by mentorship that provides significant interpersonal interaction. In spite of the potential of early MOOC ideology, MOOCs in their current form require either further development or altered expectations to significantly impact dental education.

Neutrinos help reconcile Planck measurements with the local universe.

PubMed

Wyman, Mark; Rudd, Douglas H; Vanderveld, R Ali; Hu, Wayne

2014-02-07

Current measurements of the low and high redshift Universe are in tension if we restrict ourselves to the standard six-parameter model of flat ΛCDM. This tension has two parts. First, the Planck satellite data suggest a higher normalization of matter perturbations than local measurements of galaxy clusters. Second, the expansion rate of the Universe today, H0, derived from local distance-redshift measurements is significantly higher than that inferred using the acoustic scale in galaxy surveys and the Planck data as a standard ruler. The addition of a sterile neutrino species changes the acoustic scale and brings the two into agreement; meanwhile, adding mass to the active neutrinos or to a sterile neutrino can suppress the growth of structure, bringing the cluster data into better concordance as well. For our fiducial data set combination, with statistical errors for clusters, a model with a massive sterile neutrino shows 3.5σ evidence for a nonzero mass and an even stronger rejection of the minimal model. A model with massive active neutrinos and a massless sterile neutrino is similarly preferred. An eV-scale sterile neutrino mass--of interest for short baseline and reactor anomalies--is well within the allowed range. We caution that (i) unknown astrophysical systematic errors in any of the data sets could weaken this conclusion, but they would need to be several times the known errors to eliminate the tensions entirely; (ii) the results we find are at some variance with analyses that do not include cluster measurements; and (iii) some tension remains among the data sets even when new neutrino physics is included.

Simple method of detecting sarcoptes scabiei var hominis mites among bedridden elderly patients suffering from severe scabies infestation using an adhesive-tape.

PubMed

Katsumata, Kazuo; Katsumata, Kazumi

2006-01-01

Scabies infestation is very common among bedridden elderly patients. The standard method of diagnosis for scabies by scraping the skin requires some skill. Therefore, dermatologists employ this method. However, dermatologists are usually not present in most long-term nursing units. Thus, we tried to catch mites using a strong transparent adhesive tape commercially available for packing use as an alternative method for the diagnosis of severe scabies infestation. After firmly applying the adhesive side of the tape onto an appropriate skin lesion of patients, the tape was pulled off and transferred directly onto a slide for microscopy, affixing the adhered separated part of the corneal skin. When a massive outbreak of scabies infestation occurred in May 2004 at the nursing unit of K hospital with thirty-one bedridden elderly patients, we tried to detect scabies mite using an adhesive tape. We could detect mites from six patients using this tape method. The diagnosis was confirmed by the standard scraping method. By the tape method we could observe some mites moving around and also could see a striated structure with dark red or weak red color or gray color granule-like constitution on the body of some mites. We found mites only on the skin of the fingers and toes where the skin of a patient is thin. Recently, massive scabies infestation in elderly long-term residents has been reported elsewhere. This tape method is simple and useful for diagnosis of severe scabies infestation in long-term nursing units.

A Roadmap to Fundamental Physics from LISA EMRI Observations

NASA Astrophysics Data System (ADS)

Sopuerta, Carlos F.

2010-09-01

The Laser Interferometer Space Antenna is a future space-based gravitational-wave observatory (a joint mission between the European Space Agency and the US National Aeronautics and Space Administration) that is expected to be launched during the next decade. It will operate in the low-frequency gravitational-wave band, probably the richest part of the gravitational-wave spectrum in terms of science potential, where we find: massive black hole mergers as the outcome of galaxy collisions; many galactic compact binaries; the capture and subsequent inspiral of a stellar compact object into a massive black hole; and gravitational-wave signatures from early universe physical processes connected to high-energy physics and physics not yet fully understood. In this article we focus on the third type of source, the so-called extreme-mass-ratio inspirals, a high precision tool for gravitational wave astronomy that can be used, among other things, to advance in our understanding of fundamental physics questions like the nature and structure of black holes and the details of the gravitational interaction in regimes not yet proven by other experiments/observatories. Here, we give an account of some of the progress made in the development of tools to exploit the future LISA EMRI observations, we discuss what scientific questions we can try to answer from this information and, finally, we discuss the main theoretical challenges that we face in order to develop all the necessary tools to maximize the scientific outcome and some avenues that can be followed to make progress in the near future.

Hubble Catches a Transformation in the Virgo Constellation

NASA Image and Video Library

2017-12-08

The constellation of Virgo (The Virgin) is especially rich in galaxies, due in part to the presence of a massive and gravitationally-bound collection of more than 1300 galaxies called the Virgo Cluster. One particular member of this cosmic community, NGC 4388, is captured in this image, as seen by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3. Located some 60 million light-years away, NGC 4388 is experiencing some of the less desirable effects that come with belonging to such a massive galaxy cluster. It is undergoing a transformation and has taken on a somewhat confused identity. While the galaxy’s outskirts appear smooth and featureless, a classic feature of an elliptical galaxy, its center displays remarkable dust lanes constrained within two symmetric spiral arms, which emerge from the galaxy’s glowing core — one of the obvious features of a spiral galaxy. Within the arms, speckles of bright blue mark the locations of young stars, indicating that NGC 4388 has hosted recent bursts of star formation. Despite the mixed messages, NGC 4388 is classified as a spiral galaxy. Its unusual combination of features are thought to have been caused by interactions between NGC 4388 and other galaxies in the Virgo Cluster. Gravitational interactions — from glancing blows to head-on collisions, tidal influencing, mergers, and galactic cannibalism — can be devastating to galaxies. While some may be lucky enough to simply suffer a distorted spiral arm or newly-triggered wave of star formation, others see their structure and contents completely and irrevocably altered. Image credits: ESA/NASA

Whole Genome Analyses of a Well-Differentiated Liposarcoma Reveals Novel SYT1 and DDR2 Rearrangements

PubMed Central

Egan, Jan B.; Barrett, Michael T.; Champion, Mia D.; Middha, Sumit; Lenkiewicz, Elizabeth; Evers, Lisa; Francis, Princy; Schmidt, Jessica; Shi, Chang-Xin; Van Wier, Scott; Badar, Sandra; Ahmann, Gregory; Kortuem, K. Martin; Boczek, Nicole J.; Fonseca, Rafael; Craig, David W.; Carpten, John D.; Borad, Mitesh J.; Stewart, A. Keith

2014-01-01

Liposarcoma is the most common soft tissue sarcoma, but little is known about the genomic basis of this disease. Given the low cell content of this tumor type, we utilized flow cytometry to isolate the diploid normal and aneuploid tumor populations from a well-differentiated liposarcoma prior to array comparative genomic hybridization and whole genome sequencing. This work revealed massive highly focal amplifications throughout the aneuploid tumor genome including MDM2, a gene that has previously been found to be amplified in well-differentiated liposarcoma. Structural analysis revealed massive rearrangement of chromosome 12 and 11 gene fusions, some of which may be part of double minute chromosomes commonly present in well-differentiated liposarcoma. We identified a hotspot of genomic instability localized to a region of chromosome 12 that includes a highly conserved, putative L1 retrotransposon element, LOC100507498 which resides within a gene cluster (NAV3, SYT1, PAWR) where 6 of the 11 fusion events occurred. Interestingly, a potential gene fusion was also identified in amplified DDR2, which is a potential therapeutic target of kinase inhibitors such as dastinib, that are not routinely used in the treatment of patients with liposarcoma. Furthermore, 7 somatic, damaging single nucleotide variants have also been identified, including D125N in the PTPRQ protein. In conclusion, this work is the first to report the entire genome of a well-differentiated liposarcoma with novel chromosomal rearrangements associated with amplification of therapeutically targetable genes such as MDM2 and DDR2. PMID:24505276

Geochemistry of glacial sediments in the area of the Bend massive sulfide deposit, north-central Wisconsin

USGS Publications Warehouse

Woodruff, L.G.; Attig, J.W.; Cannon, W.F.

2004-01-01

Geochemical exploration in northern Wisconsin has been problematic because of thick glacial overburden and complex stratigraphic record of glacial history. To assess till geochemical exploration in an area of thick glacial cover and complex stratigraphy samples of glacial materials were collected from cores from five rotasonic boreholes near a known massive sulfide deposit, the Bend deposit in north-central Wisconsin. Diamond drilling in the Bend area has defined a long, thin zone of mineralization at least partly intersected at the bedrock surface beneath 30-40 m of unconsolidated glacial sediments. The bedrock surface has remnant regolith and saprolite resulting from pre-Pleistocene weathering. Massive sulfide and mineralized rock collected from diamond drill core from the deposit contain high (10s to 10,000s ppm) concentrations of Ag, As, Au, Bi, Cu, Hg, Se, Te, and Tl. Geochemical properties of the glacial stratigraphic units helped clarify the sequence and source areas of several glacial ice advances preserved in the section. At least two till sheets are recognized. Over the zone of mineralization, saprolite and preglacial alluvial and lacustrine samples are preserved on the bedrock surface in a paleoriver valley. The overlying till sheet is a gray, silty carbonate till with a source hundreds of kilometers to the northwest of the study area. This gray till is overlain by red, sandy till with a source to the north in Proterozoic rocks of the Lake Superior area. The complex glacial stratigraphy confounds down-ice geochemical till exploration. The presence of remnant saprolite, preglacial sediment, and far-traveled carbonate till minimized glacial erosion of mineralized material. As a result, little evidence of down-ice glacial dispersion of lithologic or mineralogic indicators of Bend massive sulfide mineralization was found in the samples from the rotasonic cores. This study points out the importance of determining glacial stratigraphy and history, and identifying favorable lithologies required for geochemical exploration. Drift prospecting in Wisconsin and other areas near the outer limits of the Pleistocene ice sheets may not be unsuccessful, in part, because of complex stratigraphic sequences of multiple glaciations where deposition dominates over erosion. ?? 2004 Elsevier B.V. All rights reserved.

Massive star formation by accretion. I. Disc accretion

NASA Astrophysics Data System (ADS)

Haemmerlé, L.; Eggenberger, P.; Meynet, G.; Maeder, A.; Charbonnel, C.

2016-01-01

Context. Massive stars likely form by accretion and the evolutionary track of an accreting forming star corresponds to what is called the birthline in the Hertzsprung-Russell (HR) diagram. The shape of this birthline is quite sensitive to the evolution of the entropy in the accreting star. Aims: We first study the reasons why some birthlines published in past years present different behaviours for a given accretion rate. We then revisit the question of the accretion rate, which allows us to understand the distribution of the observed pre-main-sequence (pre-MS) stars in the HR diagram. Finally, we identify the conditions needed to obtain a large inflation of the star along its pre-MS evolution that may push the birthline towards the Hayashi line in the upper part of the HR diagram. Methods: We present new pre-MS models including accretion at various rates and for different initial structures of the accreting core. We compare them with previously published equivalent models. From the observed upper envelope of pre-MS stars in the HR diagram, we deduce the accretion law that best matches the accretion history of most of the intermediate-mass stars. Results: In the numerical computation of the time derivative of the entropy, some treatment leads to an artificial loss of entropy and thus reduces the inflation that the accreting star undergoes along the birthline. In the case of cold disc accretion, the existence of a significant swelling during the accretion phase, which leads to radii ≳ 100 R⊙ and brings the star back to the red part of the HR diagram, depends sensitively on the initial conditions. For an accretion rate of 10-3M⊙ yr-1, only models starting from a core with a significant radiative region evolve back to the red part of the HR diagram. We also obtain that, in order to reproduce the observed upper envelope of pre-MS stars in the HR diagram with an accretion law deduced from the observed mass outflows in ultra-compact HII regions, the fraction of the mass that is accreted onto the star should represent a decreasing fraction of the mass outflows when the mass of the accreting object increases. In other words, the accretion efficiency (mass effectively accreted onto the star with respect to the total in falling matter) decreases when the mass of the star increases.

Drilling of Submarine Shallow-water Hydrothermal Systems in Volcanic Arcs of the Tyrrhenian Sea, Italy

NASA Astrophysics Data System (ADS)

Petersen, S.; Augustin, N.; de Benedetti, A.; Esposito, A.; Gaertner, A.; Gemmell, B.; Gibson, H.; He, G.; Huegler, M.; Kleeberg, R.; Kuever, J.; Kummer, N. A.; Lackschewitz, K.; Lappe, F.; Monecke, T.; Perrin, K.; Peters, M.; Sharpe, R.; Simpson, K.; Smith, D.; Wan, B.

2007-12-01

Seafloor hydrothermal systems related to volcanic arcs are known from several localities in the Tyrrhenian Sea in water depths ranging from 650 m (Palinuro Seamount) to less than 50 m (Panarea). At Palinuro Seamount 13 holes (<5m) were drilled using Rockdrill 1 of the British Geological Survey 1 into the heavily sediment-covered deposit recovering 11 m of semi-massive to massive sulfides. Maximum recovery within a single core was 4.8 m of massive sulfides/sulfates with abundant late native sulfur overprint. The deposit is open to all sides and to depth since all drill holes ended in mineralization. Metal enrichment at the top of the deposit is evident in some cores with polymetallic (Zn, Pb, Ag) sulfides overlying more massive and dense pyritic ore. The massive sulfide mineralization at Palinuro Seamount contains a number of unusual minerals, including enargite, tennantite, luzonite, and Ag-sulfosalts, that are not commonly encountered in mid-ocean ridge massive sulfides. In analogy to epithermal deposits forming on land, the occurrence of these minerals suggests a high sulfidation state of the hydrothermal fluids during deposition implying that the mineralizing fluids were acidic and oxidizing rather than near-neutral and reducing as those forming typical base metal rich massive sulfides along mid-ocean ridges. Oxidizing conditions during sulfide deposition can probably be related to the presence of magmatic volatiles in the mineralizing fluids that may be derived from a degassing magma chamber. Elevated temperatures within sediment cores and TV-grab stations (up to 60°C) indicate present day hydrothermal fluid flow. This is also indicated by the presence of small tube-worm bushes present on top the sediment. A number of drill holes were placed around the known phreatic gas-rich vents of Panarea and recovered intense clay-alteration in some holes as well as abundant massive anhydrite/gypsum with only trace sulfides along a structural depression suggesting the presence of an anhydrite seal to a larger hydrothermal system at depth. The aim of this study is to understand the role that magmatic volatiles and phase separation play in the formation of these precious and trace element-rich shallow water (<750m) hydrothermal systems in the volcanic arcs of the Tyrrhenian Sea.

Seafloor Topographic Analysis in Staged Ocean Resource Exploration

NASA Astrophysics Data System (ADS)

Ikeda, M.; Okawa, M.; Osawa, K.; Kadoshima, K.; Asakawa, E.; Sumi, T.

2017-12-01

J-MARES (Research and Development Partnership for Next Generation Technology of Marine Resources Survey, JAPAN) has been designing a low-expense and high-efficiency exploration system for seafloor hydrothermal massive sulfide deposits in "Cross-ministerial Strategic Innovation Promotion Program (SIP)" granted by the Cabinet Office, Government of Japan since 2014. We designed a method to focus mineral deposit prospective area in multi-stages (the regional survey, semi-detail survey and detail survey) by extracted topographic features of some well-known seafloor massive sulfide deposits from seafloor topographic analysis using seafloor topographic data acquired by the bathymetric survey. We applied this procedure to an area of interest more than 100km x 100km over Okinawa Trough, including some known seafloor massive sulfide deposits. In Addition, we tried to create a three-dimensional model of seafloor topography by SfM (Structure from Motion) technique using multiple image data of Chimney distributed around well-known seafloor massive sulfide deposit taken with Hi-Vision camera mounted on ROV in detail survey such as geophysical exploration. Topographic features of Chimney was extracted by measuring created three-dimensional model. As the result, it was possible to estimate shape of seafloor sulfide such as Chimney to be mined by three-dimensional model created from image data taken with camera mounted on ROV. In this presentation, we will discuss about focusing mineral deposit prospective area in multi-stages by seafloor topographic analysis using seafloor topographic data in exploration system for seafloor massive sulfide deposit and also discuss about three-dimensional model of seafloor topography created from seafloor image data taken with ROV.

Initial conditions for accurate N-body simulations of massive neutrino cosmologies

NASA Astrophysics Data System (ADS)

Zennaro, M.; Bel, J.; Villaescusa-Navarro, F.; Carbone, C.; Sefusatti, E.; Guzzo, L.

2017-04-01

The set-up of the initial conditions in cosmological N-body simulations is usually implemented by rescaling the desired low-redshift linear power spectrum to the required starting redshift consistently with the Newtonian evolution of the simulation. The implementation of this practical solution requires more care in the context of massive neutrino cosmologies, mainly because of the non-trivial scale-dependence of the linear growth that characterizes these models. In this work, we consider a simple two-fluid, Newtonian approximation for cold dark matter and massive neutrinos perturbations that can reproduce the cold matter linear evolution predicted by Boltzmann codes such as CAMB or CLASS with a 0.1 per cent accuracy or below for all redshift relevant to non-linear structure formation. We use this description, in the first place, to quantify the systematic errors induced by several approximations often assumed in numerical simulations, including the typical set-up of the initial conditions for massive neutrino cosmologies adopted in previous works. We then take advantage of the flexibility of this approach to rescale the late-time linear power spectra to the simulation initial redshift, in order to be as consistent as possible with the dynamics of the N-body code and the approximations it assumes. We implement our method in a public code (REPS rescaled power spectra for initial conditions with massive neutrinos https://github.com/matteozennaro/reps) providing the initial displacements and velocities for cold dark matter and neutrino particles that will allow accurate, I.e. 1 per cent level, numerical simulations for this cosmological scenario.

THE STRUCTURE OF MASSIVE QUIESCENT GALAXIES AT Z {approx} 3 IN THE CANDELS-COSMOS FIELD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan Lulu; Chen Yang; Pan Zhizheng

2013-07-10

In this Letter, we use a two-color (J - L) versus (V - J) selection criterion to search massive quiescent galaxy (QG) candidates at 2.5 {<=} z {<=} 4.0 in the CANDELS-COSMOS field. We construct an H{sub F160W}-selected catalog and complement it with public auxiliary data. We finally obtain 19 passive VJL-selected (hereafter pVJL) galaxies as the possible massive QG candidates at z {approx} 3 by several constrains. We find the sizes of our pVJL galaxies are on average three to four times smaller than those of local early-type galaxies (ETGs) with analogous stellar mass. The compact size of thesemore » z {approx} 3 galaxies can be modeled by assuming their formation at z{sub form} {approx} 4-6 according to the dissipative collapse of baryons. Up to z < 4, the mass-normalized size evolution can be described by r{sub e} {proportional_to}(1 + z){sup -1.0}. Low Sersic index and axis ratio, with median values n {approx}1.5 and b/a {approx} 0.65, respectively, indicate that most of the pVJL galaxies are disk-dominated. Despite large uncertainty, the inner region of the median mass profile of our pVJL galaxies is similar to those of QGs at 0.5 < z < 2.5 and local ETGs. It indicates that local massive ETGs have been formed according to an inside-out scenario: the compact galaxies at high redshift make up the cores of local massive ETGs and then build up the outskirts according to dissipationless minor mergers.« less

Variability of Massive Young Stellar Objects in Cygnus-X

NASA Astrophysics Data System (ADS)

Thomas, Nancy H.; Hora, J. L.; Smith, H. A.

2013-01-01

Young stellar objects (YSOs) are stars in the process of formation. Several recent investigations have shown a high rate of photometric variability in YSOs at near- and mid-infrared wavelengths. Theoretical models for the formation of massive stars (1-10 solar masses) remain highly idealized, and little is known about the mechanisms that produce the variability. An ongoing Spitzer Space Telescope program is studying massive star formation in the Cygnus-X region. In conjunction with the Spitzer observations, we have conducted a ground-based near-infrared observing program of the Cygnus-X DR21 field using PAIRITEL, the automated infrared telescope at Whipple Observatory. Using the Stetson index for variability, we identified variable objects and a number of variable YSOs in our time-series PAIRITEL data of DR21. We have searched for periodicity among our variable objects using the Lomb-Scargle algorithm, and identified periodic variable objects with an average period of 8.07 days. Characterization of these variable and periodic objects will help constrain models of star formation present. This work is supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 0754568 and by the Smithsonian Institution.

Exploring the Structure and Evolution of the Universe: Multi-Band Profiles of the Known Gamma-Ray Pulsars

NASA Technical Reports Server (NTRS)

1998-01-01

As summarized in this pamphlet, some of the far-reaching underlying issues to be addressed include: What is the origin of the universe and its destiny; Why is the universe lumpy; How did the known structures of the universe evolve; How do galaxies evolve; How do massive black holes grow; How did the elemental composition of the universe evolve; What is the structure and behavior of matter in the extreme; and Is Einstein's general relativity theory right.

Wakefield Simulation of CLIC PETS Structure Using Parallel 3D Finite Element Time-Domain Solver T3P

DOE Office of Scientific and Technical Information (OSTI.GOV)

Candel, A.; Kabel, A.; Lee, L.

In recent years, SLAC's Advanced Computations Department (ACD) has developed the parallel 3D Finite Element electromagnetic time-domain code T3P. Higher-order Finite Element methods on conformal unstructured meshes and massively parallel processing allow unprecedented simulation accuracy for wakefield computations and simulations of transient effects in realistic accelerator structures. Applications include simulation of wakefield damping in the Compact Linear Collider (CLIC) power extraction and transfer structure (PETS).

Geomorphology and Ice Content of Glacier - Rock Glacier &ndash; Moraine Complexes in Ak-Shiirak Range (Inner Tien Shan, Kyrgyzstan)

NASA Astrophysics Data System (ADS)

Bolch, Tobias; Kutuzov, Stanislav; Rohrbach, Nico; Fischer, Andrea; Osmonov, Azamat

2015-04-01

Meltwater originating from the Tien Shan is of high importance for the runoff to the arid and semi-arid region of Central Asia. Previous studies estimate a glaciers' contribution of about 40% for the Aksu-Tarim Catchment, a transboundary watershed between Kyrgyzstan and China. Large parts of the Ak-Shiirak Range drain into this watershed. Glaciers in Central and Inner Tien Shan are typically polythermal or even cold and surrounded by permafrost. Several glaciers terminate into large moraine complexes which show geomorphological indicators of ice content such as thermo-karst like depressions, and further downvalley signs of creep such as ridges and furrows and a fresh, steep rock front which are typical indicators for permafrost creep ("rock glacier"). Hence, glaciers and permafrost co-exist in this region and their interactions are important to consider, e.g. for the understanding of glacial and periglacial processes. It can also be assumed that the ice stored in these relatively large dead-ice/moraine-complexes is a significant amount of the total ice storage. However, no detailed investigations exist so far. In an initial study, we investigated the structure and ice content of two typical glacier-moraine complexes in the Ak-Shiirak-Range using different ground penetrating radar (GPR) devices. In addition, the geomorphology was mapped using high resolution satellite imagery. The structure of the moraine-rock glacier complex is in general heterogeneous. Several dead ice bodies with different thicknesses and moraine-derived rock glaciers with different stages of activities could be identified. Few parts of these "rock glaciers" contain also massive ice but the largest parts are likely characterised by rock-ice layers of different thickness and ice contents. In one glacier forefield, the thickness of the rock-ice mixture is partly more than 300 m. This is only slightly lower than the maximum thickness of the glacier ice. Our measurements revealed that up to 20% of the total ice of the entire glacier-rock glacier-moraine-complex could be stored in the moraine-rock glacier parts.

Prediction of antisymmetric buffet loads on horizontal stabilizers in massively separated flows, phase II

DOT National Transportation Integrated Search

1999-05-01

The Federal Aviation Administration (FAA) has a continuing program to collect data and develop predictive methods for aircraft flight loads. Some of the most severe and potentially catastrophic flight loads are produced by separated flows. Structural...

Optimized Landing of Autonomous Unmanned Aerial Vehicle Swarms

DTIC Science & Technology

2012-06-01

understanding about the world. Examples of these emergent behaviors include construction of complex structures (e.g., hives, termite mounds), trends in economic...Sep. 2007. [16] M. Resnick, Turtles, Termites , and Traffic Jams: Explorations in Massively Parallel Microworlds. MIT Press, 1997. [Online]. Available

Investigation of geotechnical parameters from CSEM mapping and monitoring data at the oases Kharga and Baris of Sahara desert, Egypt

NASA Astrophysics Data System (ADS)

Hachay, Olga; Khachay, Oleg; Attia, Magdy; Khalil, Ahmed; Mekkawi, Mahmoud; Soliman, Mamdouh

2016-04-01

The site of investigation, oasis Kharga, is located at about 600 km south of Cairo, Egypt; Baris is about 90 km from Kharga also to south and towards more inside the desert. The work was aimed to investigate the rock mass stability at Baris and to estimate the water intake in the Oasis Kharga. A controlled source electromagnetic (CSEM) approach developed earlier by IGF UB RAS (Geophysical Federal Institute, Ural Branch of Russian Academy of Science) is applied to image the ranked deformation levels in the massive structure of the Baris. The wide profile system of observation has been used to monitor the three components of the alternating magnetic field along predefined measuring lines in the study area. Here we can show the first results that we shall continue during some cycles of monitoring. The second part of our work was linked with mapping the massif structure inside the oasis City, where only using our device we could construct the geoelectrical sections for 5 profiles and show the real structure of the water volume and its complicated structure up to 200 meters depth recording the values of real not apparent resistivity. The analytical treatments provided good information about the structure of the rock massive and its rank of degradation, the lateral distribution of the geotechnical heterogeneity, and finally a conclusive outcome about foundation stability. We can conclude that the general dynamic state close to the destruction level within the investigation areas is getting worse over the time; this is reflected in the crack's densities and positions, also on the changes in the lateral distribution of geoelectrical heterogeneity as an indicator of the saturation of the surface rock in the study area with water [1,2]. References 1. Magdy A. Atya, Olga A. Hachay, Mamdouh M. Soliman, Oleg Y. Khachay, Ahmed B. Khalill, Mahmoud Gaballah, Fathy F.Shaaban and Ibrahim A.El. Hemali. CSEM imaging of the near surface dynamics and its impact for foundation stability at quarter 27,15-th of May City, Helwan, Egypt. // Earth sciences research journal, 2010,Vol.14, N1, p.76-87. 2. Magdy A. Atya, Olga A. Hachay, Oleg Y. Khachay, El. Said A. Defining the geotechnical parameters of the medium with use of electromagnetic monitoring data with a control source for fixed frequencies. // Ural geophysical bulletin. 2014,№2,p.4-12.

The volcano-sedimentary succession of Upper Permian in Wuli area, central Qinghai-Tibetan Plateau: Sedimentology, geochemistry and paleogeography

NASA Astrophysics Data System (ADS)

Liu, Shengqian; Jiang, Zaixing; Gao, Yi

2017-04-01

Detailed observations on cores and thin sections well documented a volcano-sedimentary succession from Well TK2, which is located in Wuli area, central Qinghai-Tibetan Plateau. The TK2 volcano-sedimentary succession reflects an active sedimentary-tectonic setting in the north margin of North Qiangtang-Chamdo terrane in the late Permian epoch. Based on the observation and recognition on lithology and mineralogy, the components of TK2 succession are mainly volcanic and volcaniclastic rocks and four main lithofacies are recognized, including massive volcanic lithofacies (LF1), pyroclastic tuff lithofacies (LF2), tuffaceous sandstone lithofacies (LF3) and mudstone lithofacies (LF4). LF1 is characterized by felsic components, massive structure and porphyrotopic structure with local flow structure, which indicates submarine intrusive domes or extrusion-fed lavas that formed by magma ascents via faults or dykes. Meanwhile, its eruption style may reflect a relative high pressure compensation level (PCL) that mainly determined by water depth, which implies a deep-water environment. LF2 is composed of volcanic lapilli or ash and featured with massive structure, parallel bedding and various deformed laminations including convolve structure, slide deformation, ball-and-pillow structure, etc.. LF2 indicates the sedimentation of initial or reworked explosive products not far away from volcano centers, reflecting the proximal accumulation of volcano eruption-fed clasts or their resedimentation as debris flows. In addition, the submarine volcano eruptions may induced earthquakes that facilitate the resedimentation of unconsolidated sediments. LF3 contains abundant pyroclastic components and is commonly massive with rip-up mudstone clasts or usually interbedded with LF4. In addition, typical flute casts, scour structures and graded beddings in thin-interbedded layers of sandstone and mudstone are commonly observed, which also represents the sedimentation of debris flows or turbidity flows in a relative deep-water environment. LF4 indicates suspension deposits of distal turbidity sediments in deeper-water setting, which is mainly tuffaceous and ordinary mudstone, commonly interbedded with thin pyroclastic layers. Geochemically, the felsic volcanic rocks belong to tholeiitic to calc-alkaline series, exhibiting characteristics of right-leaning rare earth element (REE) patterns with conspicuous Eu negative anomalies, enrichments in large ion lithophile elements (LILEs) and depletions in high field-strength elements (HFSEs), which reflect an island arc environment that corresponds to the late-Permian subduction of slabs. The TK2 volcanic-sedimentary succession reveals a submarine volcano-dominated depositional model and proves the existence of a deeper water environment, at least in a restricted zone of Wuli area. However, the traditional sedimentary and paleogeographic knowledges are mostly about coal-forming transitional facies in stable environment. Therefore, the proposing of a deep-water volcano-sedimentary model will provide a further comprehension of paleogeography in southern Qinghai at late-Permian, which will also supplement the previous cognition of stable ocean-land transitional environments and provide a new sight to the paleogeographic framework of late-Permian in North Qiangtang-Chamdo terrane.

An Observational Study of Blended Young Stellar Clusters in the Galactic Plane - Do Massive Stars form First?

NASA Astrophysics Data System (ADS)

Martínez-Galarza, Rafael; Protopapas, Pavlos; Smith, Howard A.; Morales, Esteban

2018-01-01

From an observational point of view, the early life of massive stars is difficult to understand partly because star formation occurs in crowded clusters where individual stars often appear blended together in the beams of infrared telescopes. This renders the characterization of the physical properties of young embedded clusters via spectral energy distribution (SED) fitting a challenging task. Of particular relevance for the testing of star formation models is the question of whether the claimed universality of the IMF (references) is reflected in an equally universal integrated galactic initial mass function (IGIMF) of stars. In other words, is the set of all stellar masses in the galaxy sampled from a single universal IMF, or does the distribution of masses depend on the environment, making the IGIMF different from the canonical IMF? If the latter is true, how different are the two? We present a infrared SED analysis of ~70 Spitzer-selected, low mass ($<100~\\rm{M}_{\\odot}$), galactic blended clusters. For all of the clusters we obtain the most probable individual SED of each member and derive their physical properties, effectively deblending the confused emission from individual YSOs. Our algorithm incorporates a combined probabilistic model of the blended SEDs and the unresolved images in the long-wavelength end. We find that our results are compatible with competitive accretion in the central regions of young clusters, with the most massive stars forming early on in the process and less massive stars forming about 1Myr later. We also find evidence for a relationship between the total stellar mass of the cluster and the mass of the most massive member that favors optimal sampling in the cluster and disfavors random sampling for the canonical IMF, implying that star formation is self-regulated, and that the mass of the most massive star in a cluster depends on the available resources. The method presented here is easily adapted to future observations of clustered regions of star formation with JWST and other high resolution facilities.

Participatory Pedagogy in an Open Educational Course: Challenges and Opportunities

ERIC Educational Resources Information Center

Andersen, Renate; Ponti, Marisa

2014-01-01

This article presents an empirical study of an open educational course in an online peer-to-peer university (P2PU). P2PU is a nonprofit organization offering free educational opportunities. Focus is on how peers are part of creating course content in a Web 2.0 environment. Massive open online courses (MOOCs) have evolved into two different…

Scaling Student Success with Predictive Analytics: Reflections after Four Years in the Data Trenches

ERIC Educational Resources Information Center

Wagner, Ellen; Longanecker, David

2016-01-01

The metrics used in the US to track students do not include adults and part-time students. This has led to the development of a massive data initiative--the Predictive Analytics Reporting (PAR) framework--that uses predictive analytics to trace the progress of all types of students in the system. This development has allowed actionable,…

Changing Tires En Route: Michigan Rolls out Millions in School Improvement Grants

ERIC Educational Resources Information Center

Scott, Caitlin

2011-01-01

A recent massive infusion of federal funding marked a dramatic shift in the federal approach to helping low-performing schools. As part of the broad array of economic stimulus efforts included in the American Recovery and Reinvestment Act of 2009 (ARRA), the U.S. Congress appropriated an extra $3 billion for school improvement grants (SIGs) to…

Big Data in the Campus Landscape: Basic Infrastructure Support. ECAR Working Group Paper

ERIC Educational Resources Information Center

Almes, Guy T.; Zottola, Ralph J.

2014-01-01

This paper is part of series of the EDUCAUSE Center for Analysis and Research Campus Cyberinfrastructure (ECAR-CCI) Working Group. The topic of big data continues to receive a great deal of publicity because of its promise for opening new avenues of scholarly discovery and commercial opportunity. The ability to sift rapidly through massive amounts…

Exploratory Study of MOOC Learners' Demographics and Motivation: The Case of Students Involved in Groups

ERIC Educational Resources Information Center

Bayeck, Rebecca Yvonne

2016-01-01

This paper reports preliminary findings on students enrolled in a massive open online course, who were also assigned to work in groups. Part of a larger study on the effect of groups on retention and completion in MOOCs, the paper provides students' demographics (i.e., location, gender, education level, and employment status), and motivation for…

Smart Schools, Smart Growth: Investing in Education Facilities and Stronger Communities. California Builds Better Schools. Working Paper 09-1

ERIC Educational Resources Information Center

Fuller, Bruce; Vincent, Jeff; Bierbaum, Ariel H.; Kirschenbaum, Greta; McCoy, Deborah; Rigby, Jessica

2009-01-01

This report examines how California's massive and ongoing investment in school construction could better advance the shared goals of school improvement, sustainable urban growth, and equal opportunity. This brief is organized in five parts. First, the authors sketch a "framework" for how smart growth principles could help guide school…

Big Data in the Campus Landscape: Security and Privacy. ECAR Working Group Paper

ERIC Educational Resources Information Center

Barnett, William; Corn, Mike; Hillegas, Curt; Wada, Kent

2015-01-01

This paper is part of series of the EDUCAUSE Center for Analysis and Research Campus Cyberinfrastructure (ECAR-CCI) Working Group. The topic of big data continues to receive a great deal of publicity because of its promise for opening new avenues of scholarly discovery and commercial opportunity. The ability to sift rapidly through massive amounts…

Cluster Analysis-Based Approaches for Geospatiotemporal Data Mining of Massive Data Sets for Identification of Forest Threats

Treesearch

Richard Trans Mills; Forrest M Hoffman; Jitendra Kumar; William W. Hargrove

2011-01-01

We investigate methods for geospatiotemporal data mining of multi-year land surface phenology data (250 m2 Normalized Difference Vegetation Index (NDVI) values derived from the Moderate Resolution Imaging Spectrometer (MODIS) in this study) for the conterminous United States (CONUS) as part of an early warning system for detecting threats to forest ecosystems. The...

Dynamic Load Predictions for Launchers Using Extra-Large Eddy Simulations X-Les

NASA Astrophysics Data System (ADS)

Maseland, J. E. J.; Soemarwoto, B. I.; Kok, J. C.

2005-02-01

Flow-induced unsteady loads can have a strong impact on performance and flight characteristics of aerospace vehicles and therefore play a crucial role in their design and operation. Complementary to costly flight tests and delicate wind-tunnel experiments, unsteady loads can be calculated using time-accurate Computational Fluid Dynamics. A capability to accurately predict the dynamic loads on aerospace structures at flight Reynolds numbers can be of great value for the design and analysis of aerospace vehicles. Advanced space launchers are subject to dynamic loads in the base region during the ascent to space. In particular the engine and nozzle experience aerodynamic pressure fluctuations resulting from massive flow separations. Understanding these phenomena is essential for performance enhancements for future launchers which operate a larger nozzle. A new hybrid RANS-LES turbulence modelling approach termed eXtra-Large Eddy Simulations (X-LES) holds the promise to capture the flow structures associated with massive separations and enables the prediction of the broad-band spectrum of dynamic loads. This type of method has become a focal point, reducing the cost of full LES, driven by the demand for their applicability in an industrial environment. The industrial feasibility of X-LES simulations is demonstrated by computing the unsteady aerodynamic loads on the main-engine nozzle of a generic space launcher configuration. The potential to calculate the dynamic loads is qualitatively assessed for transonic flow conditions in a comparison to wind-tunnel experiments. In terms of turn-around-times, X-LES computations are already feasible within the time-frames of the development process to support the structural design. Key words: massive separated flows; buffet loads; nozzle vibrations; space launchers; time-accurate CFD; composite RANS-LES formulation.

MAPS OF MASSIVE CLUMPS IN THE EARLY STAGE OF CLUSTER FORMATION: TWO MODES OF CLUSTER FORMATION, COEVAL OR NON-COEVAL?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Higuchi, Aya E.; Saito, Masao; Mauersberger, Rainer

2013-03-10

We present maps of seven young massive molecular clumps within five target regions in C{sup 18}O (J = 1-0) line emission, using the Nobeyama 45 m telescope. These clumps, which are not associated with clusters, lie at distances between 0.7 and 2.1 kpc. We find C{sup 18}O clumps with radii of 0.5-1.7 pc, masses of 470-4200 M{sub Sun }, and velocity widths of 1.4-3.3 km s{sup -1}. All of the clumps are massive and approximately in virial equilibrium, suggesting they will potentially form clusters. Three of our target regions are associated with H II regions (CWHRs), while the other twomore » are unassociated with H II regions (CWOHRs). The C{sup 18}O clumps can be classified into two morphological types: CWHRs with a filamentary or shell-like structure and spherical CWOHRs. The two CWOHRs have systematic velocity gradients. Using the publicly released WISE database, Class I and Class II protostellar candidates are identified within the C{sup 18}O clumps. The fraction of Class I candidates among all YSO candidates (Class I+Class II) is {>=}50% in CWHRs and {<=}50% in CWOHRs. We conclude that effects from the H II regions can be seen in (1) the spatial distributions of the clumps: filamentary or shell-like structure running along the H II regions; (2) the velocity structures of the clumps: large velocity dispersion along shells; and (3) the small age spreads of YSOs. The small spreads in age of the YSOs show that the presence of H II regions tends to trigger coeval cluster formation.« less

Study of diffuse H II regions potentially forming part of the gas streams around Sgr A*

NASA Astrophysics Data System (ADS)

Armijos-Abendaño, J.; López, E.; Martín-Pintado, J.; Báez-Rubio, A.; Aravena, M.; Requena-Torres, M. A.; Martín, S.; Llerena, M.; Aldás, F.; Logan, C.; Rodríguez-Franco, A.

2018-05-01

We present a study of diffuse extended ionized gas towards three clouds located in the Galactic Centre (GC). One line of sight (LOS) is towards the 20 km s-1 cloud (LOS-0.11) in the Sgr A region, another LOS is towards the 50 km s-1 cloud (LOS-0.02), also in Sgr A, while the third is towards the Sgr B2 cloud (LOS+0.693). The emission from the ionized gas is detected from Hnα and Hmβ radio recombination lines (RRLs). Henα and Hemβ RRL emission is detected with the same n and m as those from the hydrogen RRLs only towards LOS+0.693. RRLs probe gas with positive and negative velocities towards the two Sgr A sources. The Hmβ to Hnα ratios reveal that the ionized gas is emitted under local thermodynamic equilibrium conditions in these regions. We find a He to H mass fraction of 0.29±0.01 consistent with the typical GC value, supporting the idea that massive stars have increased the He abundance compared to its primordial value. Physical properties are derived for the studied sources. We propose that the negative velocity component of both Sgr A sources is part of gas streams considered previously to model the GC cloud kinematics. Associated massive stars with what are presumably the closest H II regions to LOS-0.11 (positive velocity gas), LOS-0.02, and LOS+0.693 could be the main sources of ultraviolet photons ionizing the gas. The negative velocity components of both Sgr A sources might be ionized by the same massive stars, but only if they are in the same gas stream.

3-D readout-electronics packaging for high-bandwidth massively paralleled imager

DOEpatents

Kwiatkowski, Kris; Lyke, James

2007-12-18

Dense, massively parallel signal processing electronics are co-packaged behind associated sensor pixels. Microchips containing a linear or bilinear arrangement of photo-sensors, together with associated complex electronics, are integrated into a simple 3-D structure (a "mirror cube"). An array of photo-sensitive cells are disposed on a stacked CMOS chip's surface at a 45.degree. angle from light reflecting mirror surfaces formed on a neighboring CMOS chip surface. Image processing electronics are held within the stacked CMOS chip layers. Electrical connections couple each of said stacked CMOS chip layers and a distribution grid, the connections for distributing power and signals to components associated with each stacked CSMO chip layer.

Gravity-oriented microfluidic device for uniform and massive cell spheroid formation

PubMed Central

Lee, Kangsun; Kim, Choong; Young Yang, Jae; Lee, Hun; Ahn, Byungwook; Xu, Linfeng; Yoon Kang, Ji; Oh, Kwang W.

2012-01-01

We propose a simple method for forming massive and uniform three-dimensional (3-D) cell spheroids in a multi-level structured microfluidic device by gravitational force. The concept of orienting the device vertically has allowed spheroid formation, long-term perfusion, and retrieval of the cultured spheroids by user-friendly standard pipetting. We have successfully formed, perfused, and retrieved uniform, size-controllable, well-conditioned spheroids of human embryonic kidney 293 cells (HEK 293) in the gravity-oriented microfluidic device. We expect the proposed method will be a useful tool to study in-vitro 3-D cell models for the proliferation, differentiation, and metabolism of embryoid bodies or tumours. PMID:22662098

Covariance Matrix Estimation for Massive MIMO

NASA Astrophysics Data System (ADS)

Upadhya, Karthik; Vorobyov, Sergiy A.

2018-04-01

We propose a novel pilot structure for covariance matrix estimation in massive multiple-input multiple-output (MIMO) systems in which each user transmits two pilot sequences, with the second pilot sequence multiplied by a random phase-shift. The covariance matrix of a particular user is obtained by computing the sample cross-correlation of the channel estimates obtained from the two pilot sequences. This approach relaxes the requirement that all the users transmit their uplink pilots over the same set of symbols. We derive expressions for the achievable rate and the mean-squared error of the covariance matrix estimate when the proposed method is used with staggered pilots. The performance of the proposed method is compared with existing methods through simulations.

Gentle reenergization of electrons in merging galaxy clusters

PubMed Central

de Gasperin, Francesco; Intema, Huib T.; Shimwell, Timothy W.; Brunetti, Gianfranco; Brüggen, Marcus; Enßlin, Torsten A.; van Weeren, Reinout J.; Bonafede, Annalisa; Röttgering, Huub J. A.

2017-01-01

Galaxy clusters are the most massive constituents of the large-scale structure of the universe. Although the hot thermal gas that pervades galaxy clusters is relatively well understood through observations with x-ray satellites, our understanding of the nonthermal part of the intracluster medium (ICM) remains incomplete. With Low-Frequency Array (LOFAR) and Giant Metrewave Radio Telescope (GMRT) observations, we have identified a phenomenon that can be unveiled only at extremely low radio frequencies and offers new insights into the nonthermal component. We propose that the interplay between radio-emitting plasma and the perturbed intracluster medium can gently reenergize relativistic particles initially injected by active galactic nuclei. Sources powered through this mechanism can maintain electrons at higher energies than radiative aging would allow. If this mechanism is common for aged plasma, a population of mildly relativistic electrons can be accumulated inside galaxy clusters providing the seed population for merger-induced reacceleration mechanisms on larger scales such as turbulence and shock waves. PMID:28983512

Rock Slide Monitoring by Using TDR Inclinometers

NASA Astrophysics Data System (ADS)

Drusa, Marián; Bulko, Roman

2016-12-01

The geotechnical monitoring of the slope deformations is widespread at present time. In many geological localities and civil engineering construction areas, monitoring is a unique tool for controlling of negative factors and processes, also inform us about actual state of rock environment or interacting structures. It is necessary for risk assessment. In our case, geotechnical monitoring is controlling rockslide activity around in the future part of motorway. The construction of new highway route D1 from Bratislava to Košice crosses the territory which is affected by a massive rockslide close to Kraľovany village. There was a need to monitor the activity of a large unstable rockslide with deep shear planes. In this case of underground movement activity, the Department of Geotechnics of the University of Žilina installed inclinometers at the unstable area which worked on Time Domain Reflectometry (TDR) principle. Based on provided measurements, effectivity and suitability of TDR inclinometers for monitoring of deep underground movement activity is demonstrated.

History of Hubble Space Telescope (HST)

NASA Image and Video Library

1995-01-01

These eerie, dark, pillar-like structures are actually columns of cool interstellar hydrogen gas and dust that are also incubators for new stars. The pillars protrude from the interior wall of a dark molecular cloud like stalagmites from the floor of a cavern. They are part of the Eagle Nebula (also called M16), a nearby star-forming region 7,000 light-years away, in the constellation Serpens. The ultraviolet light from hot, massive, newborn stars is responsible for illuminating the convoluted surfaces of the columns and the ghostly streamers of gas boiling away from their surfaces, producing the dramatic visual effects that highlight the three-dimensional nature of the clouds. This image was taken on April 1, 1995 with the Hubble Space Telescope Wide Field Planetary Camera 2. The color image is constructed from three separate images taken in the light of emission from different types of atoms. Red shows emissions from singly-ionized sulfur atoms, green shows emissions from hydrogen, and blue shows light emitted by doubly-ionized oxygen atoms.

Vibrant Soundbridge Implantation: Floating Mass Transducer Coupled with the Stapes Head and Embedded in Fat.

PubMed

Liu, Qingsong; Feng, Guodong; Shang, Yingying; Wang, Suju; Gao, Zhiqiang

2018-04-26

Subtotal petrosectomy may be performed for refractory chronic middle ear diseases, such as massive cholesteatoma or recurrent otitis media. It involves permanent obliteration of the operative cavity, thus precluding the chance to restore conductive hearing via traditional inertial ossicular prostheses. The Vibrant Soundbridge (VSB) is an alternative option for hearing rehabilitation. Vibrant energy is delivered into the inner ear via a floating mass transducer (FMT), which can be coupled with any part of the middle ear acoustic transmission structure. To restore the hearing of a young woman with cholesteatoma, we combined subtotal petrosectomy with obliteration of the cavity and VSB implantation with an FMT coupled to the stapes head. Two years of follow-up demonstrated excellent auditory rehabilitation, improved sound source localization ability, and a lower speech recognition threshold. This study showed that the FMT works well in an obliterated cavity, and the experience acquired through this successful exploration is worth disseminating. © 2018 S. Karger AG, Basel.

Cosmic evolution of star formation properties of galaxies

NASA Astrophysics Data System (ADS)

Kim, Sungeun

2014-01-01

Development of bolometer array and camera at submillimeter wavelength has played an important role in detecting submillimeter bright galaxies, so called submillimeter galaxies. These galaxies seem to be progenitors of present-day massive galaxies and account for their considerable contributions to the light from the early universe and their expected high star formation rates if there is a close link between the submillimeter galaxies and the star formation activities, and the interstellar dust in galaxies is mainly heated by the star light. We review assembly of submillimeter galaxies chosen from the AzTEC and the Herschel SPIRE/PACS data archives, and investigate their spectral energy distribution fits including the data at other wavelengths to deduce details about stellar parameters including star formation rates and parameters yielding the metallicity, composition and abundance in dust, and disc structure of these galaxies. This work has been supported in part by Mid-career Researcher Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology 2011-0028001.

Gentle reenergization of electrons in merging galaxy clusters.

PubMed

de Gasperin, Francesco; Intema, Huib T; Shimwell, Timothy W; Brunetti, Gianfranco; Brüggen, Marcus; Enßlin, Torsten A; van Weeren, Reinout J; Bonafede, Annalisa; Röttgering, Huub J A

2017-10-01

Galaxy clusters are the most massive constituents of the large-scale structure of the universe. Although the hot thermal gas that pervades galaxy clusters is relatively well understood through observations with x-ray satellites, our understanding of the nonthermal part of the intracluster medium (ICM) remains incomplete. With Low-Frequency Array (LOFAR) and Giant Metrewave Radio Telescope (GMRT) observations, we have identified a phenomenon that can be unveiled only at extremely low radio frequencies and offers new insights into the nonthermal component. We propose that the interplay between radio-emitting plasma and the perturbed intracluster medium can gently reenergize relativistic particles initially injected by active galactic nuclei. Sources powered through this mechanism can maintain electrons at higher energies than radiative aging would allow. If this mechanism is common for aged plasma, a population of mildly relativistic electrons can be accumulated inside galaxy clusters providing the seed population for merger-induced reacceleration mechanisms on larger scales such as turbulence and shock waves.

ENGINEERING-GEOLOGY SITE APPRAISAL OF THE FEDERAL CAPITAL TERRITORY, NIGERIA.

USGS Publications Warehouse

Ege, J.R.; Griffitts, W.R.; Overstreet, W.C.

1985-01-01

The 7,700-km**2-area Federal Capital Territory, Nigeria, is underlain by crystalline igneous and metamorphic rocks of Precambrian age. Laterite caps many hills of Cretaceous rock, some hills of Precambrian rock, and crops out near stream banks in the east and northeast. The most conspicuous structural features are a broad 'J'-shaped fold traversing the eastern and central part of the Territory and a north-trending shear zone along the eastern boundary. The soils of the Territory are lateritic and belong to the SW-SP-SM (Unified Soil Classification System) groups covering Precambrian migmatites, gneisses and granites and the SC group covering Cretaceous sediments and Precambrian mica-rich schists. The engineering characteristics of the rocks are medium- to high-strength massive and gneissic rock, low-to medium-strength bedded rock, and low-strength foliated and sheared rock. An area of at least 800 km**2 is free from apparent geological hazards and should be suitable for construction of a capital city, its environs and supporting facilities.

Fragmentation of Massive Dense Cores Down to <~ 1000 AU: Relation between Fragmentation and Density Structure

NASA Astrophysics Data System (ADS)

Palau, Aina; Estalella, Robert; Girart, Josep M.; Fuente, Asunción; Fontani, Francesco; Commerçon, Benoit; Busquet, Gemma; Bontemps, Sylvain; Sánchez-Monge, Álvaro; Zapata, Luis A.; Zhang, Qizhou; Hennebelle, Patrick; di Francesco, James

2014-04-01

In order to shed light on the main physical processes controlling fragmentation of massive dense cores, we present a uniform study of the density structure of 19 massive dense cores, selected to be at similar evolutionary stages, for which their relative fragmentation level was assessed in a previous work. We inferred the density structure of the 19 cores through a simultaneous fit of the radial intensity profiles at 450 and 850 μm (or 1.2 mm in two cases) and the spectral energy distribution, assuming spherical symmetry and that the density and temperature of the cores decrease with radius following power-laws. Even though the estimated fragmentation level is strictly speaking a lower limit, its relative value is significant and several trends could be explored with our data. We find a weak (inverse) trend of fragmentation level and density power-law index, with steeper density profiles tending to show lower fragmentation, and vice versa. In addition, we find a trend of fragmentation increasing with density within a given radius, which arises from a combination of flat density profile and high central density and is consistent with Jeans fragmentation. We considered the effects of rotational-to-gravitational energy ratio, non-thermal velocity dispersion, and turbulence mode on the density structure of the cores, and found that compressive turbulence seems to yield higher central densities. Finally, a possible explanation for the origin of cores with concentrated density profiles, which are the cores showing no fragmentation, could be related with a strong magnetic field, consistent with the outcome of radiation magnetohydrodynamic simulations. The James Clerk Maxwell Telescope is operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the United Kingdom, the Netherlands Organisation for Scientific Research, and the National Research Council of Canada.

Utilizing borehole electrical images to interpret lithofacies of fan-delta: A case study of Lower Triassic Baikouquan Formation in Mahu Depression, Junggar Basin, China

NASA Astrophysics Data System (ADS)

Yuan, Rui; Zhang, Changmin; Tang, Yong; Qu, Jianhua; Guo, Xudong; Sun, Yuqiu; Zhu, Rui; Zhou, Yuanquan (Nancy)

2017-11-01

Large-scale conglomerate fan-delta aprons were typical deposits on the slope of Mahu Depression during the Early Triassic. Without outcrops, it is difficult to study the lithofacies only by examining the limited cores from the main oil-bearing interval of the Baikouquan Formation. Borehole electrical imaging log provides abundant high-resolution geologic information that is obtainable only from real rocks previously. Referring to the lithology and sedimentary structure of cores, a case study of fan-deltas in the Lower Triassic Baikouquan Formation of the Mahu Depression presents a methodology for interpreting the complicated lithofacies utilizing borehole electrical images. Eleven types of lithologies and five types of sedimentary structures are summarized in borehole electrical images. The sediments are fining upward from gravel to silt and clay in the Baikouquan Formation. Fine-pebbles and granules are the main deposits in T1b1 and T1b2, but sandstones, siltstones and mudstones are more developed in T1b3. The main sedimentary textures are massive beddings, cross beddings and scour-and-fill structures. Parallel and horizontal beddings are more developed in T1b3 relatively. On integrated analysis of the lithology and sedimentary structure, eight lithofacies from electrical images, referred to as image lithofacies, is established for the fan-deltas. Granules to coarse-pebbles within massive beddings, granules to coarse-pebbles within cross and parallel beddings, siltstones within horizontal and massive beddings are the most developed lithofacies respectively in T1b1, T1b2 and T1b3. It indicates a gradual rise of the lake level of Mahu depression during the Early Triassic, with the fan-delta aprons retrograding towards to the margin of the basin. Therefore, the borehole electrical imaging log compensate for the limitation of cores of the Baikouquan Formation, providing an effective new approach to interpret the lithofacies of fan-delta.

Sierra Structural Dynamics User's Notes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reese, Garth M.

2015-10-19

Sierra/SD provides a massively parallel implementation of structural dynamics finite element analysis, required for high fidelity, validated models used in modal, vibration, static and shock analysis of weapons systems. This document provides a users guide to the input for Sierra/SD. Details of input specifications for the different solution types, output options, element types and parameters are included. The appendices contain detailed examples, and instructions for running the software on parallel platforms.

Massively parallel unsupervised single-particle cryo-EM data clustering via statistical manifold learning

PubMed Central

Wu, Jiayi; Ma, Yong-Bei; Congdon, Charles; Brett, Bevin; Chen, Shuobing; Xu, Yaofang; Ouyang, Qi

2017-01-01

Structural heterogeneity in single-particle cryo-electron microscopy (cryo-EM) data represents a major challenge for high-resolution structure determination. Unsupervised classification may serve as the first step in the assessment of structural heterogeneity. However, traditional algorithms for unsupervised classification, such as K-means clustering and maximum likelihood optimization, may classify images into wrong classes with decreasing signal-to-noise-ratio (SNR) in the image data, yet demand increased computational costs. Overcoming these limitations requires further development of clustering algorithms for high-performance cryo-EM data processing. Here we introduce an unsupervised single-particle clustering algorithm derived from a statistical manifold learning framework called generative topographic mapping (GTM). We show that unsupervised GTM clustering improves classification accuracy by about 40% in the absence of input references for data with lower SNRs. Applications to several experimental datasets suggest that our algorithm can detect subtle structural differences among classes via a hierarchical clustering strategy. After code optimization over a high-performance computing (HPC) environment, our software implementation was able to generate thousands of reference-free class averages within hours in a massively parallel fashion, which allows a significant improvement on ab initio 3D reconstruction and assists in the computational purification of homogeneous datasets for high-resolution visualization. PMID:28786986

Massively parallel unsupervised single-particle cryo-EM data clustering via statistical manifold learning.

PubMed

Wu, Jiayi; Ma, Yong-Bei; Congdon, Charles; Brett, Bevin; Chen, Shuobing; Xu, Yaofang; Ouyang, Qi; Mao, Youdong

2017-01-01

Structural heterogeneity in single-particle cryo-electron microscopy (cryo-EM) data represents a major challenge for high-resolution structure determination. Unsupervised classification may serve as the first step in the assessment of structural heterogeneity. However, traditional algorithms for unsupervised classification, such as K-means clustering and maximum likelihood optimization, may classify images into wrong classes with decreasing signal-to-noise-ratio (SNR) in the image data, yet demand increased computational costs. Overcoming these limitations requires further development of clustering algorithms for high-performance cryo-EM data processing. Here we introduce an unsupervised single-particle clustering algorithm derived from a statistical manifold learning framework called generative topographic mapping (GTM). We show that unsupervised GTM clustering improves classification accuracy by about 40% in the absence of input references for data with lower SNRs. Applications to several experimental datasets suggest that our algorithm can detect subtle structural differences among classes via a hierarchical clustering strategy. After code optimization over a high-performance computing (HPC) environment, our software implementation was able to generate thousands of reference-free class averages within hours in a massively parallel fashion, which allows a significant improvement on ab initio 3D reconstruction and assists in the computational purification of homogeneous datasets for high-resolution visualization.

The beaming of subhalo accretion

NASA Astrophysics Data System (ADS)

Libeskind, Noam I.

2016-10-01

We examine the infall pattern of subhaloes onto hosts in the context of the large-scale structure. We find that the infall pattern is essentially driven by the shear tensor of the ambient velocity field. Dark matter subhaloes are preferentially accreted along the principal axis of the shear tensor which corresponds to the direction of weakest collapse. We examine the dependence of this preferential infall on subhalo mass, host halo mass and redshift. Although strongest for the most massive hosts and the most massive subhaloes at high redshift, the preferential infall of subhaloes is effectively universal in the sense that its always aligned with the axis of weakest collapse of the velocity shear tensor. It is the same shear tensor that dictates the structure of the cosmic web and hence the shear field emerges as the key factor that governs the local anisotropic pattern of structure formation. Since the small (sub-Mpc) scale is strongly correlated with the mid-range (~ 10 Mpc) scale - a scale accessible by current surveys of peculiar velocities - it follows that findings presented here open a new window into the relation between the observed large scale structure unveiled by current surveys of peculiar velocities and the preferential infall direction of the Local Group. This may shed light on the unexpected alignments of dwarf galaxies seen in the Local Group.

RNA design rules from a massive open laboratory

PubMed Central

Lee, Jeehyung; Kladwang, Wipapat; Lee, Minjae; Cantu, Daniel; Azizyan, Martin; Kim, Hanjoo; Limpaecher, Alex; Gaikwad, Snehal; Yoon, Sungroh; Treuille, Adrien; Das, Rhiju

2014-01-01

Self-assembling RNA molecules present compelling substrates for the rational interrogation and control of living systems. However, imperfect in silico models—even at the secondary structure level—hinder the design of new RNAs that function properly when synthesized. Here, we present a unique and potentially general approach to such empirical problems: the Massive Open Laboratory. The EteRNA project connects 37,000 enthusiasts to RNA design puzzles through an online interface. Uniquely, EteRNA participants not only manipulate simulated molecules but also control a remote experimental pipeline for high-throughput RNA synthesis and structure mapping. We show herein that the EteRNA community leveraged dozens of cycles of continuous wet laboratory feedback to learn strategies for solving in vitro RNA design problems on which automated methods fail. The top strategies—including several previously unrecognized negative design rules—were distilled by machine learning into an algorithm, EteRNABot. Over a rigorous 1-y testing phase, both the EteRNA community and EteRNABot significantly outperformed prior algorithms in a dozen RNA secondary structure design tests, including the creation of dendrimer-like structures and scaffolds for small molecule sensors. These results show that an online community can carry out large-scale experiments, hypothesis generation, and algorithm design to create practical advances in empirical science. PMID:24469816

IgG4-related pleural disease presenting as a massive bilateral effusion.

PubMed

Ishida, Atsuko; Furuya, Naoki; Nishisaka, Takashi; Mineshita, Masamichi; Miyazawa, Teruomi

2014-07-01

A 74-year-old woman with massive bilateral pleural effusion, which was exudative in nature, and with mononuclear cell predominance underwent a pleuroscopy. Parietal pleura were thickened and partly reddish in color. Biopsy specimens taken from the parietal pleura revealed lymphoplasmacytic inflammation with fibrosis. As her performance status rapidly worsened with thoracentesis, we performed bilateral pleurodesis using talc. Pathologic evaluation of the pleural biopsy specimen with immunohistochemical staining revealed 91 IgG4-positive plasma cells per high-power field and an IgG4/IgG ratio of 91%. Thus, the diagnosis of pleuritis from IgG4-related disease was established. Our case suggests that IgG4-related disease is one of the causes of pleural effusion, and it should be included in the differential diagnosis of unexplained pleuritis.

Properties of LEGUS Clusters Obtained with Different Massive-Star Evolutionary Tracks

NASA Astrophysics Data System (ADS)

Wofford, A.; Charlot, S.; Eldridge, J. J.

We compute spectral libraries for populations of coeval stars using state-of-the-art massive-star evolutionary tracks that account for different astrophysics including rotation and close-binarity. Our synthetic spectra account for stellar and nebular contributions. We use our models to obtain E(B - V ), age, and mass for six clusters in spiral galaxy NGC 1566, which have ages of < 50 Myr and masses of > 5 x 104M⊙ according to standard models. NGC 1566 was observed from the NUV to the I-band as part of the imaging Treasury HST program LEGUS: Legacy Extragalactic UV Survey. We aim to establish i) if the models provide reasonable fits to the data, ii) how well the models and photometry are able to constrain the cluster properties, and iii) how different the properties obtained with different models are.

Discrimination of rock classes and alteration products in southwestern Saudi Arabia with computer-enhanced LANDSAT data

NASA Technical Reports Server (NTRS)

Blodget, H. W.; Gunther, F. J.; Podwysocki, M. H.

1978-01-01

Digital LANDSAT MSS data for an area in the southwestern Arabian Shield were computer-enhanced to improve discrimination of rock classes, and recognition of gossans associated with massive sulphide deposits. The test area is underlain by metamorphic rocks that are locally intruded by granites; these are partly overlain by sandstones. The test area further includes the Wadi Wassat and Wadi Qatan massive sulphide deposits, which are commonly capped by gossans of ferric oxides, silica, and carbonates. Color patterns and boundaries on contrast-stretched ratio color composite imagery, and on complementary images constructed using principal component and canonical analyses transformations, correspond exceptionally well to 1:100,000 scale field maps. A qualitative visual comparison of information content showed that the ratio enhancement provided the best overall image for identification of rock type and alteration products.

Distributed Fast Self-Organized Maps for Massive Spectrophotometric Data Analysis †.

PubMed

Dafonte, Carlos; Garabato, Daniel; Álvarez, Marco A; Manteiga, Minia

2018-05-03

Analyzing huge amounts of data becomes essential in the era of Big Data, where databases are populated with hundreds of Gigabytes that must be processed to extract knowledge. Hence, classical algorithms must be adapted towards distributed computing methodologies that leverage the underlying computational power of these platforms. Here, a parallel, scalable, and optimized design for self-organized maps (SOM) is proposed in order to analyze massive data gathered by the spectrophotometric sensor of the European Space Agency (ESA) Gaia spacecraft, although it could be extrapolated to other domains. The performance comparison between the sequential implementation and the distributed ones based on Apache Hadoop and Apache Spark is an important part of the work, as well as the detailed analysis of the proposed optimizations. Finally, a domain-specific visualization tool to explore astronomical SOMs is presented.