1,151 research outputs found

    Remote sensing of cloud distribution

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    Day and night mapping of the global distribution of the horizontal cloud-cover and the corresponding cloud-top pressure levels can be derived from the same infrared data used to derive clear column temperature profiles. Applications to the 15 micrometer VTPR data are given. Extension of this approach for the determination of the radiative transfer properties of clouds is presented and the possibility of using such information to infer cloud types is discussed

    Structure of a Plane Shock Layer

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    The structure of a plane shock wave is discussed and the expected range of applicability of the Navierā€Stokes equations within the shock layer is outlined. The shock profiles are computed using the Bhatnagarā€Grossā€Krook model of the Boltzmann equation and a uniformly converging iteration scheme starting from the Navierā€Stokes solution. It is shown that the Navierā€Stokes solution remains a good approximation in the highā€pressure region of the shock layer up to approximately the point of maximum stress for all shock strengths. In the lowā€pressure region, the correct profiles deviate with increasing shock strength from the Navierā€Stokes solution. The physical significance of the kinetic model used and the relation of the present study to previous theoretical and experimental work is discussed

    Theoretical and Experimental Aspects of the Shock Structure Problem

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    Flow of rarefied gases - Shock wave structure proble

    The Blackhole-Dark Matter Halo Connection

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    We explore the connection between the central supermassive blackholes (SMBH) in galaxies and the dark matter halo through the relation between the masses of the SMBHs and the maximum circular velocities of the host galaxies, as well as the relationship between stellar velocity dispersion of the spheroidal component and the circular velocity. Our assumption here is that the circular velocity is a proxy for the mass of the dark matter halo. We rely on a heterogeneous sample containing galaxies of all types. The only requirement is that the galaxy has a direct measurement of the mass of its SMBH and a direct measurement of its circular velocity and its velocity dispersion. Previous studies have analyzed the connection between the SMBH and dark matter halo through the relationship between the circular velocity and the bulge velocity dispersion, with the assumption that the bulge velocity dispersion stands in for the mass of the SMBH, via the well{}-established SMBH mass{}-bulge velocity dispersion relation. Using intermediate relations may be misleading when one is studying them to decipher the active ingredients of galaxy formation and evolution. We believe that our approach will provide a more direct probe of the SMBH and the dark matter halo connection. We find that the correlation between the mass of supermassive blackholes and the circular velocities of the host galaxies is extremely weak, leading us to state the dark matter halo may not play a major role in regulating the blackhole growth in the present Universe.Comment: Accepted for publication in the Ap

    The GLAS physical inversion method for analysis of HIRS2/MSU sounding data

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    Goddard Laboratory for Atmospheric Sciences has developed a method to derive atmospheric temperature profiles, sea or land surface temperatures, sea ice extent and snow cover, and cloud heights and fractional cloud, from HIRS2/MSU radiance data. Chapter 1 describes the physics used in the radiative transfer calculations and demonstrates the accuracy of the calculations. Chapter 2 describes the rapid transmittance algorithm used and demonstrates its accuracy. Chapter 3 describes the theory and application of the techniques used to analyze the satellite data. Chapter 4 shows results obtained for January 1979

    Investigations carried out under the Director's Discretionary Fund

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    This annual report comprises a set of summaries, describing task objectives, progress and results or accomplishments, future outlook, and financial status for each director's discretionary fund (DDF) task that was active during fiscal year 1984. Publications and conference presentations related to the work are listed. The individual reports are categorized as interim or final according to whether the task efforts are ongoing or completed. A partial list of new tasks to be initiated with fiscal year 1985 funds and a glossary of abbreviations and acronyms, used by the task authors in their summaries are included. The table of contents lists the DDF reports in sequence by their task number, which is derived from the 13-digit code assigned to account for the fund awarded to the task project

    Collaborative Evaluative Inquiry: A Model for Improving Mathematics Instruction in Urban Elementary Schools

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    In this article, the authors describe the cyclical process of a collaborative evaluative inquiry project and the data collected throughout the projectā€”data that not only informed next steps during the project but also show promise in documenting the benefits of such projects. Over a period of 18 months, seven elementary teachers from a Kā€“6 urban elementary school collaborated with university personnel using Parsonsā€™s (2002) Evaluative Inquiry Model, a 5-stage, cyclical model that includes defining, planning, and investigating challenges; collecting, analyzing, and synthesizing data; and communicating findings that transpire through collaborative inquiry. Overall, the project focused on improving the elementary teachersā€™ skills of inquiry and, in turn, their mathematics instruction and studentsā€™ learning outcomes. The long-term goal was to enhance teachersā€™ roles in their schools by affording them the opportunities to make informed decisions throughout their teaching based on an effective and skillful use of data

    The relationship between public listing, context, multi-nationality and internal CSR

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    Are MNEs more socially responsible, and where is this more likely to occur? Are firms less responsible in emerging or transitional economies, and what impact does the dominant national corporate governance regime have? We explore the association between public listing and the existence of a CSR code within specific institutional settings and assess whether MNEs are any different to their local counterparts, based on an internationally comparative survey. We find that listed firms as well as firms from civil law countries are more likely to have CSR statements. MNEs are also more likely to have CSR statement, independent of their country of origin. While we find consistent evidence of a correlation between the existence of a CSR statement and investment in staff training, the correlation between the former and employee-friendly HRM is weaker

    Determination of antioxidant activity of saffron taken from the flower of Crocus sativus grown in Lebanon

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    Since oxidative stress has been implicated in most common cause of death, especially in case of cancer and cardiovascular disease, natural substances and spices that show antioxidant effects merit a closer examination. Saffron is the yellow natural spice derived from the flower of Crocus sativus and used as a coloring agent in many foods worldwide. In this study, we determined the total polyphenols content in the Lebanese saffron and the antioxidant effects of different extracts from this saffron in vitro using electrolysis of physiological solution for generation of free radicals (FR) in the presence of colorimetric indicator N,N-di-ethyl-P-phenylenedialanine; the absorbance was measured spectrophotometrically at 515 nm. Histophathological studies allowed us to observe the damages caused by FR in the isolated organs of hamsters (kidney, liver, lungs, and heart) and on the other hand the protection that saffron provided to these vital organs. By using assay kits, we evaluated the levels of lipid peroxidation and superoxide dismutase activity, the important free radical scavenging enzyme. The results showed that both boiled and soaked saffron at 0.45 mg/ml are highly effective against FR generated by electrolysis and against the damages caused to the organs tested as observed by light microscopy. Moreover, saffron significantly (p < 0.05) decreased lipid peroxidation and increased superoxide dismutase activity in all tissues used as compared to control. We concluded that Lebanese saffron strongly protects vital organs against oxidative stress.Key words: Crocus sativus, oxidative stress, free radicals, Lebanese saffron, antioxidant activity, free radicals scavengers
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