1,499 research outputs found

    Autonomous support for microorganism research in space

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    A preliminary design for performing on orbit, autonomous research on microorganisms and cultured cells/tissues is presented. An understanding of gravity and its effects on cells is crucial for space exploration as well as for terrestrial applications. The payload is designed to be compatible with the Commercial Experiment Transporter (COMET) launch vehicle, an orbiter middeck locker interface, and with Space Station Freedom. Uplink/downlink capabilities and sample return through controlled reentry are available for all carriers. Autonomous testing activities are preprogrammed with in-flight reprogrammability. Sensors for monitoring temperature, pH, light, gravity levels, vibrations, and radiation are provided for environmental regulation and experimental data collection. Additional experimental data acquisition includes optical density measurement, microscopy, video, and film photography. On-board full data storage capabilities are provided. A fluid transfer mechanism is utilized for inoculation, sampling, and nutrient replenishment of experiment cultures. In addition to payload design, representative experiments were developed to ensure scientific objectives remained compatible with hardware capabilities. The project is defined to provide biological data pertinent to extended duration crewed space flight including crew health issues and development of a Controlled Ecological Life Support System (CELSS). In addition, opportunities are opened for investigations leading to commercial applications of space, such as pharmaceutical development, modeling of terrestrial diseases, and material processing

    Spatial oscillations in the spontaneous emission rate of an atom inside a metallic wedge

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    A method of images is applied to study the spontaneous emission of an atom inside a metallic wedge with an opening angle of π/N\pi/N, where N is an arbitrary positive integer. We show the method of images gives a rate formula consistent with that from Quantum Electrodynamics. Using the method of images, we show the correspondence between the oscillations in the spontaneous emission rate and the closed-orbits of emitted photon going away and returning to the atom inside the wedge. The closed-orbits can be readily constructed using the method of images and they are also extracted from the spontaneous emission rate.Comment: 8 figure

    Mickey Rat, No. 2

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    volumes : illustrations. Title from indicia. Library has nos. 1-4 (1972-1982) The Adler Archive of Underground Comix, Gift of Bill Adler.https://digitalcommons.risd.edu/specialcollections_adlerarchive_undergroundcomix/1032/thumbnail.jp

    Mickey Rat, No. 4

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    volumes : illustrations. Title from indicia. Library has nos. 1-4 (1972-1982) The Adler Archive of Underground Comix, Gift of Bill Adler.https://digitalcommons.risd.edu/specialcollections_adlerarchive_undergroundcomix/1034/thumbnail.jp

    Mickey Rat, No. 3

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    volumes : illustrations. Title from indicia. Library has nos. 1-4 (1972-1982) The Adler Archive of Underground Comix, Gift of Bill Adler.https://digitalcommons.risd.edu/specialcollections_adlerarchive_undergroundcomix/1033/thumbnail.jp

    Yellow-fluorescing calcite from Sterling Hill

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    Engineering Design: the Information Component

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    The curriculum of the Bucknell University Chemical Engineering Department includes a required senior year capstone course titled Process Engineering, with an emphasis on process design. For the past ten years library research has been a significant component of the coursework, and students working in teams meet with the librarian throughout the semester to explore a wide variety of information resources required for their project. The assignment has been the same from 1989 to 1999. Teams of students are responsible for designing a safe, efficient, and profitable process for the dehydrogenation of ethylbenzene to styrene monomer. A series of written reports on their chosen process design is a significant course outcome. While the assignment and the specific chemical technology have not changed radically in the past decade, the process of research and discovery has evolved considerably. This paper describes the solutions offered in 1989 to meet the information needs of the chemical engineering students at Bucknell University, and the evolution in research brought about by online databases, electronic journals, and the Internet, making the process of discovery a completely different experience in 1999

    X-ray scattering from surfaces: discrete and continuous components of roughness

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    Incoherent surface scattering yields a statistical description of the surface, due to the ensemble averaging over many independently sampled volumes. Depending on the state of the surface and direction of the scattering vector relative to the surface normal, the height distribution is discrete, continuous, or a combination of the two. We present a treatment for the influence of multimodal surface height distributions on Crystal Truncation Rod scattering. The effects of a multimodal height distribution are especially evident during in situ monitoring of layer-by-layer thin-film growth via Pulsed Laser Deposition. We model the total height distribution as a convolution of discrete and continuous components, resulting in a broadly applicable parameterization of surface roughness which can be applied to other scattering probes, such as electrons and neutrons. Convolution of such distributions could potentially be applied to interface or chemical scattering. Here we find that this analysis describes accurately our experimental studies of SrTiO3 annealing and homoepitaxial growth.Comment: 15 pages, 7 figure

    Thermal expansion of kyanite at ambient pressure: An X-ray powder diffraction study up to 1000 °C

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    AbstractThe thermal expansion coefficients of kyanite at ambient pressure have been investigated by an X-ray powder diffraction technique with temperatures up to 1000 °C. No phase transition was observed in the experimental temperature range. Data for the unit-cell parameters and temperatures were fitted empirically resulting in the following thermal expansion coefficients: αa = 5.8(3) × 10−5, αb = 5.8(1) × 10−5, αc = 5.2(1) × 10−5, and αV = 7.4(1) × 10−3 °C−1, in good agreement with a recent neutron powder diffraction study. On the other hand, the variation of the unit-cell angles α, β and γ of kyanite with increase in temperature is very complicated, and the agreement among all studies is poor. The thermal expansion data at ambient pressure reported here and the compression data at ambient temperature from the literature suggest that, for the kyanite lattice, the most and least thermally expandable directions correspond to the most and least compressible directions, respectively

    INTRODUCTION TO SELECTING SUBSETS OF TRAITS FOR QUANTITATIVE TRAIT LOCI ANALYSIS

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    Quantitative trait loci (QTL) mapping is a popular statistical method that is often used in agricultural applications to identify genomic regions associated with phenotypic traits of interest. In its most common form, a QTL analysis tests one phenotypic trait at a time using a variety of research hypotheses that depend on the application. When multiple traits are available, there are considerable benefits to analyzing subsets of biologically related traits in a multipletrait QTL mapping framework. Determining the most informative subset(s) of traits is the critical challenge that we address in this work. We present our approach, as well as simulations that demonstrate the performance. We also discuss an application of our approach as applied to an Arabidopsis thaliana data set
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