2,583 research outputs found

    Vegetation water use based on a thermal and optical remote sensing model in the mediterranean region of Doñana

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    Terrestrial evapotranspiration (ET) is a central process in the climate system, is a major component in the terrestrial water budget, and is responsible for the distribution of water and energy on land surfaces especially in arid and semiarid areas. In order to inform water management decisions especially in scarce water environments, it is important to assess ET vegetation use by differentiating irrigated socio-economic areas and natural ecosystems. The global remote sensing ET product MOD16 has proven to underestimate ET in semiarid regions where ET is very sensitive to soil moisture. The objective of this research was to test whether a modified version of the remote sensing ET model PT-JPL, proven to perform well in drylands at Eddy Covariance flux sites using the land surface temperature as a proxy to the surface moisture status (PT-JPL-thermal), could be up-scaled at regional levels introducing also a new formulation for net radiation from various MODIS products. We applied three methods to track the spatial and temporal characteristics of ET in the World Heritage UNESCO Doñana region: (i) a locally calibrated hydrological model (WATEN), (ii) the PT-JPL-thermal, and (iii) the global remote sensing ET product MOD16. The PT-JPL-thermal showed strong agreement with the WATEN ET in-situ calibrated estimates (ρ = 0.78, ρ1month-lag = 0.94) even though the MOD16 product did not (ρ = 0.48). The PT-JPL-thermal approach has proven to be a robust remote sensing model for detecting ET at a regional level in Mediterranean environments and it requires only air temperature and incoming solar radiation from climatic databases apart from freely available satellite products

    Optimized design of local shielding for the IFMIF/EVEDA beam dump

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    This paper describes the local shielding design process of the IFMIF/EVEDA Beam Dump and the most relevant results obtained from the simulations. Different geometries and materials have been considered, and the design has been optimized taking into account the origin of the doses, the effect of the walls of the accelerator vault and the space restrictions. The initial idea was to shield the beam stopper with a large water tank of easy transport and dismantling but it was shown to be insufficient to satisfy the dose limit requirements, basically due to photon dose, and hence a denser shield combining hydrogenous and heavy materials was preferred. It will be shown that, with this new shielding, dose rate outside the accelerator vault during operation comply with the legal limits and unrestricted maintenance operations inside most of the vault are possible after a reasonable cooling time after shutdown

    SMART (Shop floor Modeling, Analysis and Reporting Tool Project

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    This document presents summarizes the design and prototype of the Shop floor Modeling, Analysis, and Reporting Tool (S.M.A.R.T.) A detailed description of it is found on the full documentation given to the NASA liaison. This documentation is also found on the A.R.I.S.E. Center web site, under a projected directory. Only authorized users can gain access to this site

    Human Mars Entry, Descent and Landing Architecture Study: Rigid Decelerators

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    Several technology investments are required to develop Mars human scale Entry, Descent, and Landing (EDL) systems. Studies play the critical role of identifying the most feasible technical paths and high payoff investments. The goal of NASA's Entry, Descent and Landing Architecture Study is to inform those technology investments. In Phase 1 of the study, a point design for one lifting-body-like rigid decelerator vehicle, was developed. In Phase 2, a capsule concept was also considered to determine how it accommodated the human mission requirements. This paper summarizes the concept of operations for both rigid vehicles to deliver a 20-metric ton (t) payload to the surface of Mars. Details of the vehicle designs and flight performance are presented along with a packaging, mass sizing, and a launch vehicle fairing assessment. Finally, recommended technology investments based on the analysis of the rigid vehicles are provided

    First lunar outpost

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    Design and research efforts at the University of Puerto Rico have focused on the evaluation and refinement of the Habitability Criteria for a prolonged human presence in space during the last four years. Living quarters for a Mars mission and a third generation lunar base concept were proposed. This academic year, 1991-92, work on further refinement of the habitability criteria and design of partial gravity furniture was carried on. During the first semester, design alternatives for furniture necessary in a habitat design optimized for lunar and Martian environments were developed. Designs are based on recent research data from lunar and Mars gravity simulations, and current NASA standards. Artifacts will be submitted to NASA architects to be tested in KC-135 flights. Test findings will be submitted for incorporation in future updates to NASA habitat design standards. Second semester work was aimed at integrating these findings into the First Lunar Outpost (FLO), a mission scenario currently being considered by NASA. The mission consists of a manned return to the moon by crews of four astronauts for periods of 45 days. The major hardware components of the mission are as follows: (1) a Crew Module for the delivery of the crew and their supplies, and (2) the Habitat Module, which will arrive on the Moon unmanned. Our design efforts concentrated on this Habitat Module and on application of habitability criteria. Different geometries for the pressure vessel and their impact on the interior architecture were studied. Upon the selection of a geometry, a more detailed analysis of the interior design was performed, taking into consideration the reduced gravity, and the protection against radiation, micrometeorites, and the extreme temperature variation. A proposal for a FLO was submitted by the students, consisting essentially of a 24-feet (7.3 m.) by 35-feet (10.67 m) high vertical cylinder with work areas, crew quarters, galley, wardroom, leisure facilities, health maintenance, waste management, EVA operations facilities, and safe havens

    Hypothalamic pregnenolone mediates recognition memory in the context of metabolic disorders

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    Obesity and type-2 diabetes are associated with cognitive dysfunction. Since the hypothalamus is implicated in energy balance control and memory disorders, we hypothesized that specific neurons in this brain region are at the interface of metabolism and cognition. Acute obesogenic diet administration in mice impaired recognition memory due to defective production of the neurosteroid-precursor pregnenolone in the hypothalamus. Genetic interference with pregnenolone synthesis by Star deletion in hypothalamic POMC, but not AgRP neurons, deteriorated recognition memory independently of metabolic disturbances. Our data suggested that pregnenolone's effects on cognitive function were mediated via an autocrine mechanism on POMC neurons, influencing hippocampal long-term potentiation. The relevance of central pregnenolone on cognition was also confirmed in metabolically-unhealthy obese patients. Our data reveals an unsuspected role for POMC neuron-derived neurosteroids in cognition. These results provide the basis for a framework to investigate new facets of POMC neuron biology with implications for cognitive disorders

    UBVRI Light Curves of 44 Type Ia Supernovae

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    We present UBVRI photometry of 44 type-Ia supernovae (SN Ia) observed from 1997 to 2001 as part of a continuing monitoring campaign at the Fred Lawrence Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics. The data set comprises 2190 observations and is the largest homogeneously observed and reduced sample of SN Ia to date, nearly doubling the number of well-observed, nearby SN Ia with published multicolor CCD light curves. The large sample of U-band photometry is a unique addition, with important connections to SN Ia observed at high redshift. The decline rate of SN Ia U-band light curves correlates well with the decline rate in other bands, as does the U-B color at maximum light. However, the U-band peak magnitudes show an increased dispersion relative to other bands even after accounting for extinction and decline rate, amounting to an additional ~40% intrinsic scatter compared to B-band.Comment: 84 authors, 71 pages, 51 tables, 10 figures. Accepted for publication in the Astronomical Journal. Version with high-res figures and electronic data at http://astron.berkeley.edu/~saurabh/cfa2snIa

    Overexpression. of dehydrin tas14 gene improves the osmotic stress imposed by drought and salinity in tomato

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    [EN] One strategy to increase the level of drought and salinity tolerance is the transfer of genes codifying different types of proteins functionally related to macromolecules protection, such as group 2 of late embryogenesis abundant (LEA) proteins or dehydrins. The TAS14 dehydrin was isolated and characterized in tomato and its expression was induced by osmotic stress (NaCl and mannitol) and abscisic acid (ABA) [Godoy et al., Plant Mol Biol 1994;26:1921-1934], yet its function in drought and salinity tolerance of tomato remains elusive. In this study, transgenic tomato plants overexpressing tas14 gene under the control of the 35SCaMV promoter were generated to assess the function of tas14 gene in drought and salinity tolerance. The plants overexpressing tas14 gene achieved improved long-term drought and salinity tolerance without affecting plant growth under non-stress conditions. A mechanism of osmotic stress tolerance via osmotic potential reduction and solutes accumulation, such as sugars and K+ is operating in tas14 overexpressing plants in drought conditions. A similar mechanism of osmotic stress tolerance was observed under salinity. Moreover, the overexpression of tas14 gene increased Na+ accumulation only in adult leaves, whereas in young leaves, the accumulated solutes were K+ and sugars, suggesting that plants overexpressing tas14 gene are able to distribute the Na+ accumulation between young and adult leaves over a prolonged period in stressful conditions. Measurement of ABA showed that the action mechanism of tas14 gene is associated with an earlier and greater accumulation of ABA in leaves during short-term periods. A good feature for the application of this gene in improving drought and salt stress tolerance is the fact that its constitutive expression does not affect plant growth under non-stress conditions, and tolerance induced by overexpression of tas14 gene was observed at the different stress degrees applied to the long term. (C) 2011 Elsevier GmbH. All rights reserved.This work was supported by the Spanish Ministry of Science and Innovation through grant AGL2009-13388-C03 and by the Council of Science and Technology from the Region of Murcia (Spain) (Fundacion SENECA) through grant 04553/GERM/06.Muñoz Mayor, A.; Pineda Chaza, BJ.; García Abellán, JO.; Antón Martínez, MT.; García Sogo, B.; Sánchez Bel, P.; Flores, FB.... (2012). Overexpression. of dehydrin tas14 gene improves the osmotic stress imposed by drought and salinity in tomato. Journal of Plant Physiology. 169(5):459-468. https://doi.org/10.1016/j.jplph.2011.11.018S459468169

    Low NKp30, NKp46 and NKG2D expression and reduced cytotoxic activity on NK cells in cervical cancer and precursor lesions

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    <p>Abstract</p> <p>Background</p> <p>Persistent high risk HPV infection can lead to cervical cancer, the second most common malignant tumor in women worldwide. NK cells play a crucial role against tumors and virus-infected cells through a fine balance between activating and inhibitory receptors. Expression of triggering receptors NKp30, NKp44, NKp46 and NKG2D on NK cells correlates with cytolytic activity against tumor cells, but these receptors have not been studied in cervical cancer and precursor lesions. The aim of the present work was to study NKp30, NKp46, NKG2D, NKp80 and 2B4 expression in NK cells from patients with cervical cancer and precursor lesions, in the context of HPV infection.</p> <p>Methods</p> <p>NKp30, NKp46, NKG2D, NKp80 and 2B4 expression was analyzed by flow cytometry on NK cells from 59 patients with cervical cancer and squamous intraepithelial lesions. NK cell cytotoxicity was evaluated in a 4 hour CFSE/7-AAD flow cytometry assay. HPV types were identified by PCR assays.</p> <p>Results</p> <p>We report here for the first time that NK cell-activating receptors NKp30 and NKp46 are significantly down-regulated in cervical cancer and high grade squamous intraepithelial lesion (HGSIL) patients. NCRs down-regulation correlated with low cytolytic activity, HPV-16 infection and clinical stage. NKG2D was also down-regulated in cervical cancer patients.</p> <p>Conclusion</p> <p>Our results suggest that NKp30, NKp46 and NKG2D down-regulation represent an evasion mechanism associated to low NK cell activity, HPV-16 infection and cervical cancer progression.</p
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