1,227 research outputs found

    A tertiary mammalian fauna from the Avawatz Mountains, San Bernardino County, California

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    The Tertiary mammal occurrence in the Avawatz Mountains, discovered in 1932 by the late H. W. Nickerson of Yucca Grove, California, was reported first to the Los Angeles County Museum. W. M. Strong, sent out by the Museum to make a survey of the area, assembled a small collection, but the material was so fragmentary that interest subsided. Subsequently, in 1935, in the course of archaeological field studies, Mr. and Mrs. William H. Campbell of Twenty-nine Palms rediscovered the fossiliferous locality on the south flank of the Avawatz Mountains. The occurrence was brought to the attention of E. L. Furlong, who visited the region with Mr. and Mrs. Campbell. Most of the material now in the collections of the California Institute of Technology was acquired during these visits. Since then, several brief collecting trips have been made to the area

    The dynamical properties of dense filaments in the infrared dark cloud G035.39-00.33

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    Infrared Dark Clouds (IRDCs) are unique laboratories to study the initial conditions of high-mass star and star cluster formation. We present high-sensitivity and high-angular resolution IRAM PdBI observations of N2H+ (1-0) towards IRDC G035.39-00.33. It is found that G035.39-00.33 is a highly complex environment, consisting of several mildly supersonic filaments (sigma_NT/c_s ~1.5), separated in velocity by <1 km s^-1 . Where multiple spectral components are evident, moment analysis overestimates the non-thermal contribution to the line-width by a factor ~2. Large-scale velocity gradients evident in previous single-dish maps may be explained by the presence of substructure now evident in the interferometric maps. Whilst global velocity gradients are small (<0.7 km s^-1 pc^-1), there is evidence for dynamic processes on local scales (~1.5-2.5 km s^-1 pc^-1 ). Systematic trends in velocity gradient are observed towards several continuum peaks. This suggests that the kinematics are influenced by dense (and in some cases, starless) cores. These trends are interpreted as either infalling material, with accretion rates ~(7 \pm 4)x10^-5 M_sun yr^-1 , or expanding shells with momentum ~24 \pm 12 M_sun km s^-1 . These observations highlight the importance of high-sensitivity and high-spectral resolution data in disentangling the complex kinematic and physical structure of massive star forming regions.Comment: 25 pages, 23 figures, accepted for publication in MNRA

    Gas Kinematics and Excitation in the Filamentary IRDC G035.39-00.33

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    Some theories of dense molecular cloud formation involve dynamical environments driven by converging atomic flows or collisions between preexisting molecular clouds. The determination of the dynamics and physical conditions of the gas in clouds at the early stages of their evolution is essential to establish the dynamical imprints of such collisions, and to infer the processes involved in their formation. We present multi-transition 13CO and C18O maps toward the IRDC G035.39-00.33, believed to be at the earliest stages of evolution. The 13CO and C18O gas is distributed in three filaments (Filaments 1, 2 and 3), where the most massive cores are preferentially found at the intersecting regions between them. The filaments have a similar kinematic structure with smooth velocity gradients of ~0.4-0.8 km s-1 pc-1. Several scenarios are proposed to explain these gradients, including cloud rotation, gas accretion along the filaments, global gravitational collapse, and unresolved sub-filament structures. These results are complemented by HCO+, HNC, H13CO+ and HN13C single-pointing data to search for gas infall signatures. The 13CO and C18O gas motions are supersonic across G035.39-00.33, with the emission showing broader linewidths toward the edges of the IRDC. This could be due to energy dissipation at the densest regions in the cloud. The average H2 densities are ~5000-7000 cm-3, with Filaments 2 and 3 being denser and more massive than Filament 1. The C18O data unveils three regions with high CO depletion factors (f_D~5-12), similar to those found in massive starless cores.Comment: 20 pages, 14 figures, 6 tables, accepted for publication in MNRA

    Overture - Object-oriented tools for overset grid applications

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    The Overture framework is an object-oriented environment for solving partial differential equations in two and three space dimensions. It is a collection of C++ libraries that enables the use of finite difference and finite volume methods at a level that hides the details of the associated data structures. Overture can be used to solve problems in complicated, moving geometries using the method of overlapping grids. It has support for grid generation, difference operators, boundary conditions, data-base access and graphics. Short sample code segments are presented to show the power of this approach

    COLLABORATIVE BEHAVIOURS DRIVING EFFECTIVE INNOVATION: AN EXPLORATORY STUDY (25)

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    This paper focuses on an imaginative internship programme, named Extreme Blue®, which has been introduced by IBM® to help them identify high potential, future graduate level recruits, by getting teams of internees to work together on practical computing projects, for some of IBM’s key collaborative partners and potential customers1 . The research team were given full access to the Extreme Blue participants, and they used a qualitative research approach, based upon interviews, observations and document reviews, to investigate the nature and effectiveness of the software development approaches that were adopted. The key finding was that the Extreme Blue initiative enabled groups of inexperienced, undergraduate internees, to be melded into effective software development teams, in a very short period of time. Moreover, this exploratory study makes a potentially important contribution to the software development literature by providing important new insights regarding an approach, which can deliver timely and effective software solutions, which are both innovative and have the potential to deliver real business value. The study also makes a potential contribution to the developing literature on graduate recruitment in the IS sphere, by answering the question: how can organisations improve their ability to identify and attract the very best graduate, to be employed in technically-oriented roles

    The effects of singeing on the histological appearance of some visceral organs in the red Sokoto goat (Capra hirrcus)

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    The histology of visceral organs from singed Red Sokoto goats were assessed for reliability for use as histopathological samples from singed abattoir specimen. This becomes important as samples for histopathology and histology of goats in Nigeria have been sourced from singed carcasses, with no available literature reporting on the effect of singeing on the histological appearance of tissues from such sample. Hence, this study will fill this knowledge gap. The unfixed samples post-singeing were grouped into time periods of an hour interval up to 3 hours. They were subsequently fixed after allocated tie framed and processed for histological observation. The slides were graded on a scale of 1 to 3, where 1 referred to highly distorted, 2 referred to moderately distorted and 3 referred to mildly distorted. The samples from unsigned viscera that were fixed immediately served as control. Most of the visceral organs showed moderate distortions, except the intestines which degenerated to highly distorted architecture after 3 hours. The stomach compartments displayed normal organ structure similar to the control samples. Blood extravasations were observed in most of the organs. This project shows that samples from singed carcasses that are fixed within 2 hours post-singeing are stable for histology or histopathological studies. It also implied that abattoir samples for histopathogy should be sent to the nearest laboratory about 2 hours radius for fixation and processing to generate reliable data.Key words: Singeing, organ architecture, fixation, histology, histopathology, Nigeri
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