137 research outputs found

    Data Sources for Improving Estimates of the Global Burden of Injuries: Call for Contributors

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    Kavi Bhalla and colleagues invite individuals and organizations to provide local injury data sources to help inform estimates of the global burden of injuries

    A 2km-size asteroid challenging the rubble-pile spin barrier – A case for cohesion

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    The rubble pile spin barrier is an upper limit on the rotation rate of asteroids larger than ~200-300. m. Among thousands of asteroids with diameters larger than ~300. m, only a handful of asteroids are known to rotate faster than 2.0. h, all are in the sub-km range (≤0.6. km). Here we present photometric measurements suggesting that (60716) 2000 GD65, an S-complex, inner-main belt asteroid with a relatively large diameter of 2.3-0.7+0.6km, completes one rotation in 1.9529. ±. 0.0002. h. Its unique diameter and rotation period allow us to examine scenarios about asteroid internal structure and evolution: a rubble pile bound only by gravity; a rubble-pile with strong cohesion; a monolithic structure; an asteroid experiencing mass shedding; an asteroid experiencing YORP spin-up/down; and an asteroid with a unique octahedron shape results with a four-peak lightcurve and a 3.9. h period. We find that the most likely scenario includes a lunar-like cohesion that can prevent (60716) 2000 GD65 from disrupting without requiring a monolithic structure or a unique shape. Due to the uniqueness of (60716) 2000 GD65, we suggest that most asteroids typically have smaller cohesion than that of lunar regolith. Keywords: Asteroids; Asteroids, rotation; Rotational dynamics; PhotometryUnited States. National Aeronautics and Space Administration (Grant NNX12AL26G

    Asteroid rotation periods from the Palomar Transient Factory survey

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    The Palomar Transient Factory (PTF) is a synoptic survey designed to explore the transient and variable sky in a wide variety of cadences. We use PTF observations of fields that were observed multiple times (>=10) per night, for several nights, to find asteroids, construct their lightcurves and measure their rotation periods. Here we describe the pipeline we use to achieve these goals and present the results from the first four (overlapping) PTF fields analyzed as part of this program. These fields, which cover an area of 21 deg^2, were observed on four nights with a cadence of ~20 min. Our pipeline was able to detect 624 asteroids, of which 145 (~20%) were previously unknown. We present high quality rotation periods for 88 main-belt asteroids and possible period or lower limit on the period for an additional 85 asteroids. For the remaining 451 asteroids, we present lower limits on their photometric amplitudes. Three of the asteroids have lightcurves that are characteristic of binary asteroids. We estimate that implementing our search for all existing high-cadence PTF data will provide rotation periods for about 10,000 asteroids mainly in the magnitude range ~14 to ~20.Comment: 16 pages, 11 figures, 6 tables + Supplementary Material. Accepted for publication in MNRA

    The present state of research into industrial clusters and districts. Content analysis of material published 1997-2006

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    [EN] The aim of this work is to help gain a better understanding of the research conducted on territorial agglomerations of firms at a multidisciplinary level. To this end, an analysis was performed of the contents of the most significant scientific literature on economics, management, planning and development, urban studies and geography published over the period 1997-2006. From the results, a database of 142 papers from 43 journals was then elaborated. An analysis of these works reveals the level of development of the main lines of research in this field and, consequently, makes it possible to detect the topics that require greater attention and that can be the object of future research for researchers and academics. The main conclusions include the growing number of studies conducted on the subject in recent years, as well as a greater predominance of empirical research over conceptual work, and the existence of a significant change in the topics or lines of research throughout the period under study. © 2012 Copyright Taylor and Francis Group, LLC.This research was financed by the Spanish Ministry of Education and Science, National R&D & Innovation Plan 2007–2010, under the project entitled “El Distrito Industrial: el impacto del Capital Social sobre la Gestio´n de la Cadena de Suministro” (The Industrial District: the impact of Social Capital on the management of the Supply Chain) (SEJ2007- 62876/ECON).Martinez-Fernandez, M.; Capó Vicedo, J.; Vallet-Bellmunt, T. (2012). The present state of research into industrial clusters and districts. Content analysis of material published 1997-2006. European Planning Studies. 20(2):281-304. doi:10.1080/09654313.2012.650906S28130420

    Formation of gullies on Mars by debris flows triggered by CO_2 sublimation

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    Martian gully landforms resemble terrestrial debris flows formed by the action of liquid water and have thus been interpreted as evidence for potential habitable environments on Mars within the past few millennia. However, ongoing gully formation has been detected under surface conditions much too cold for liquid water, but at times in the martian year when a thin layer of seasonal CO_2 frost is present and defrosting above the regolith. These observations suggest that the CO_2 condensation–sublimation cycle could play a role in gully formation. Here we use a thermo-physical numerical model of the martian regolith underlying a CO_2 ice layer and atmosphere to show that the pores beneath the ice layer can be filled with CO_2 ice and subjected to extreme pressure variations during the defrosting season. The subsequent gas fluxes can destabilize the regolith material and induce gas-lubricated debris flows with geomorphic characteristics similar to martian gullies. Moreover, we find that subsurface CO_2 ice condensation, sublimation and pressurization occurs at conditions found at latitudes and slope orientations where gullies are observed. We conclude that martian gullies can result from geologic dry ice processes that have no terrestrial analogues and do not require liquid water. Such dry ice processes may have helped shape the evolution of landforms elsewhere on the martian surface

    Comparative gustatory responses in four species of gerbilline rodents

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    Integrated taste responses to chemical stimulation of the tongue were recorded from the intact chorda tympani nerve in four species of gerbils ( Meriones libycus, M. shawi, M. unguiculatus and Psammomys obesus ).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47116/1/359_2004_Article_BF00618177.pd
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