2,536 research outputs found

    Lunar material transport vehicle

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    The proposed vehicle, the Lunar Material Transport Vehicle (LMTV), has a mission objective of efficient lunar soil material transport. The LMTV was designed to meet a required set of performance specifications while operating under a given set of constraints. The LMTV is essentially an articulated steering, double-ended dump truck. The vehicle moves on four wheels and has two identical chassis halves. Each half consists of a chassis frame, a material bucket, two wheels with integral curvilinear synchronous motors, a fuel cell and battery arrangement, an electromechanically actuated dumping mechanism, and a powerful microprocessor. The vehicle, as designed, is capable of transporting up to 200 cu ft of material over a one mile round trip per hour. The LMTV is capable of being operated from a variety of sources. The vehicle has been designed as simply as possible with attention also given to secondary usage of components

    A Teachers guide: The basic characteristics of wetlands and why they are important to the environment

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    The purpose of this thesis is to develop an educational guide about wetlands that can be used by 3rd- 12th grade teachers. This guide will enable students to learn about wetlands and why they are important to our environment. I will provide examples and a series of activities that teachers can use in the classroom to help their students better understand the benefits and function of wetlands

    Relative effects on global warming of halogenated methanes and ethanes of social and industrial interest

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    The relative potential global warming effects for several halocarbons (chlorofluorocarbons (CFC's)-11, 12, 113, 114, and 115; hydrochlorofluorocarbons (HCFC's) 22, 123, 124, 141b, and 142b; and hydrofluorocarbons (HFC's) 125, 134a, 143a, and 152a; carbon tetrachloride; and methyl chloroform) were calculated by two atmospheric modeling groups. These calculations were based on atmospheric chemistry and radiative convective models to determine the chemical profiles and the radiative processes. The resulting relative greenhouse warming when normalized to the effect of CFC-11 agree reasonably well as long as we account for differences between modeled lifetimes. Differences among results are discussed. Sensitivity of relative warming values is determined with respect to trace gas levels assumed. Transient relative global warming effects are analyzed

    Patterns of Psychotherapy Attendance in Emerging and Mature Adults

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    Approximately 760,000 emerging adults use outpatient psychotherapy in the U.S. each year (Olfson et al.,2002). Emerging adults are 1.6-7.9 times more likely to drop out of mental health treatment than fully mature adults (Edlund et al., 2002; Olfson et al., 2002). This Study compared temporal patterns of attendance and non attendance between emerging and mature adult

    Ursinus College Bulletin Vol. 6, No. 6

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    A digitized copy of the March 1890 Ursinus College Bulletin.https://digitalcommons.ursinus.edu/ucbulletin/1054/thumbnail.jp

    A disk census for the nearest group of young stars: Mid-infrared observations of the TW Hydrae Association

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    A group of young, active stars in the vicinity of TW Hydrae has recently been identified as a possible physical association with a common origin. Given its proximity (\sim50 pc), age (\sim10 Myr) and abundance of binary systems, the TW Hya Association is ideally suited to studies of diversity and evolution of circumstellar disks. Here we present mid-infrared observations of 15 candidate members of the group, 11 of which have no previous flux measurements at wavelengths longer than 2μ\mum. We report the discovery of a possible 10μ\mum excess in CD -33^{\circ}7795, which may be due to a circumstellar disk or a faint, as yet undetected binary companion. Of the other stars, only TW Hya, HD 98800, Hen 3-600A, and HR 4796A -- all of which were detected by IRAS -- show excess thermal emission. Our 10μ\mum flux measurements for the remaining members of the Association are consistent with photospheric emission, allowing us to rule out dusty inner disks. In light of these findings, we discuss the origin and age of the TW Hya Association as well as implications for disk evolution timescales.Comment: 10 pages and 1 PostScript figure, accepted for publication in The Astrophysical Journal Letter

    Pulsewidth dependence of ozone interference in the laser fluorescence measurement of OH in the atmosphere

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    By varying the pulsewidth of the output from two dye lasers, we have verified experimentally that the steady‐state interference level of OH due to laser‐induced dissociation of ozone decreases linearly with decreasing pulsewidth of the exciting radiation. At low pressures, further reduction in the interference level due to the transient nature of OH formation processes was also observed. These results should greatly facilitate measurements of OH concentrations in the atmosphere.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70170/2/JCPSA6-66-5-2118-1.pd

    Re\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e7\u3c/sub\u3e-catalyzed reaction of hemiacetals and aldehydes with O-, S-, and C-nucleophiles

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    Re(VII) oxides catalyze the acetalization, monoperoxyacetalization, monothioacetalization and allylation of hemiacetals. The reactions, which take place under mild conditions and at low catalyst loadings, can be conducted using hemiacetals, the corresponding O-silyl ethers, and, in some cases, the acetal dimers. Aldehydes react under similar conditions to furnish good yields of dithioacetals. Reactions of hemiacetals with nitrogen nucleophiles are unsuccessful. 1,2-Dioxolan-3-ols (peroxyhemiacetals) undergo Re(VII)-promoted etherification but not allylation. Hydroperoxyacetals (1-alkoxyhydroperoxides) undergo selective exchange of the alkoxide group in the presence of either Re2O7 or a Brønsted acid

    Re\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e7\u3c/sub\u3e-catalyzed reaction of hemiacetals and aldehydes with O-, S-, and C-nucleophiles

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    Re(VII) oxides catalyze the acetalization, monoperoxyacetalization, monothioacetalization and allylation of hemiacetals. The reactions, which take place under mild conditions and at low catalyst loadings, can be conducted using hemiacetals, the corresponding O-silyl ethers, and, in some cases, the acetal dimers. Aldehydes react under similar conditions to furnish good yields of dithioacetals. Reactions of hemiacetals with nitrogen nucleophiles are unsuccessful. 1,2-Dioxolan-3-ols (peroxyhemiacetals) undergo Re(VII)-promoted etherification but not allylation. Hydroperoxyacetals (1-alkoxyhydroperoxides) undergo selective exchange of the alkoxide group in the presence of either Re2O7 or a Brønsted acid
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