406 research outputs found

    Convective structure of the planetary boundary layer of the ocean during gale

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    The structure of the Planetary Boundary Layer (PBL) was measured, using an airborne lidar, over the Atlantic Ocean during several intensive observation periods of the Genesis of Atlantic Lows Experiment (GALE). Primary emphasis is on the understanding of the convective structure within the PBL during cold air outbreaks. Cold outbreaks generally occur in between the development of coastal storms; and behind a cold front sweeping down from Canada out across the Atlantic. As the cold dry air moves over the relatively warm ocean, it is heated and moistened. The transfer of latent and sensible heat during these events accounts for most of the heat transfer between the ocean and atmosphere during winter. Moistening of the PBL during these eventsis believed to be an important factor in determining the strength of development of the storm system which follows. In general, the more PBL moisture available as latent heat the higher the probability the storm will intensify. The major mechanism for vertical mixing of heat and mositure within the PBL is cellular convection. Knowlede of the organization and structure of the convection is important for understanding the process

    Lidar observations and modeling of cold air outbreaks during MASEX and GALE

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    As part of MASEX and GALE a number of research flights were carried out over the Marine Boundary Layer (MBL) during periods when extremely cold and dry continental air was flowing out over the warm coastal waters at the east coast of the U.S. Such periods, which are named cold air outbreaks are characterized by massive warming and moistening of the MBL resulting in rapid entrainment conditions. As the MBL deepens as a function of fetch over the ocean, clouds develop. The line of cloud formation typically follows the coast line closely as has been observed many times from satellite imagery. The backscatter data from the NASA Goddard airborne lidar, which was used to measure the depth of the MBL in great detail, is ideally suited to verify parametrized models of boundary layer growth rate. The data indicates that the deepening MBL gradually develops clouds at its top. Those clouds form an integral part of the MBL and exercise an important influence on the energy cycle within the MBL. It is suggested that the rapid entrainment observed during overcast conditions represent an increase in efficiency of conversion of available turbulence kinetic energy into entrainment energy

    Gas analyzer for bi-gaseous mixtures Patent

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    Gas analyzer for bi-gaseous mixtures suitable for use in test facilitie

    Strategies against nonsense: oxadiazoles as translational readthrough-inducing drugs (TRIDs)

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    This review focuses on the use of oxadiazoles as translational readthrough-inducing drugs (TRIDs) to rescue the functional full-length protein expression in mendelian genetic diseases caused by nonsense mutations. These mutations in specific genes generate premature termination codons (PTCs) responsible for the translation of truncated proteins. After a brief introduction on nonsense mutations and their pathological effects, the features of various classes of TRIDs will be described discussing differences or similarities in their mechanisms of action. Strategies to correct the PTCs will be presented, particularly focusing on a new class of Ataluren-like oxadiazole derivatives in comparison to aminoglycosides. Additionally, recent results on the efficiency of new candidate TRIDs in restoring the production of the cystic fibrosis transmembrane regulator (CFTR) protein will be presented. Finally, a prospectus on complementary strategies to enhance the effect of TRIDs will be illustrated together with a conclusive paragraph about perspectives, opportunities, and caveats in developing small molecules as TRIDs

    Performance modeling of ultraviolet Raman lidar systems for daytime profiling of atmospheric water vapor

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    We describe preliminary results from a comprehensive computer model developed to guide optimization of a Raman lidar system for measuring daytime profiles of atmospheric water vapor, emphasizing an ultraviolet, solar-blind approach

    Phylogenetic relationships of the italian populations of horseshoe whip snake hemorrhois hippocrepis (Serpentes, colubridae)

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    Hemorrhois hippocrepis is a colubrid snake with a West Mediterranean distribution. It is widespread in the Iberian Peninsula and Northwest Africa. The only Italian populations are found on the islands of Sardinia and Pantel-leria. The phylogenetic relationships of these insular populations have been analysed for the first time on the basis of the mitochondrial DNA cytochrome b gene. The sequences were compared with those available from the geographic range of this species. The analyses showed that the Italian samples are part of a lineage that groups Tunisian and East Algerian samples, with which they share the same haplotype. These results strongly support the hypothesis of a recent origin of the Italian populations of Hemorrhois hippocrepis, probably determined by human-mediated dispersal from North Africa

    Calibration of radiation codes in climate models: Comparison of calculations with observations from the SPECtral Radiation Experiment (SPECTRE)

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    The primary goal of SPECTRE is to: close the loopholes by which longwave radiation models have eluded incisive comparisons with measurements. Likewise, the experimental approach was quite simple in concept, namely: accurately measure the zenith infrared radiance at high spectral resolution while simultaneously profiling the radiatively important atmospheric properties with conventional and remote sensing devices. The field phase of SPECTRE was carried out as part of FIRE Cirrus II, and detailed spectra of the down welling radiance were obtained by several interferometers simultaneous to the measurement of the optical properties of the atmosphere. We are now well along in the process of analyzing the data and calibrating radiation codes so that they may be used more effectively in climate related studies. The calibration is being done with models ranging from the most detailed (line-by-line) to the broad-band parameterizations used in climate models. This paper summarizes our progress in the calibration for clear-sky conditions. When this stage is completed, we will move on to the calibration for cirrus conditions
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