4,763 research outputs found

    Intelligent Design Will Survive: Kitzmiller v. Dover

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    Intelligent Design Will Surviv

    Intelligent Design Will Survive: Kitzmiller v. Dover

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    Intelligent Design Will Surviv

    A method of evaluating efficiency during space-suited work in a neutral buoyancy environment

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    The purpose was to investigate efficiency as related to the work transmission and the metabolic cost of various extravehicular activity (EVA) tasks during simulated microgravity (whole body water immersion) using three space suits. Two new prototype space station suits, AX-5 and MKIII, are pressurized at 57.2 kPa and were tested concurrently with the operationally used 29.6 kPa shuttle suit. Four male astronauts were asked to perform a fatigue trial on four upper extremity exercises during which metabolic rate and work output were measured and efficiency was calculated in each suit. The activities were selected to simulate actual EVA tasks. The test article was an underwater dynamometry system to which the astronauts were secured by foot restraints. All metabolic data was acquired, calculated, and stored using a computerized indirect calorimetry system connected to the suit ventilation/gas supply control console. During the efficiency testing, steady state metabolic rate could be evaluated as well as work transmitted to the dynamometer. Mechanical efficiency could then be calculated for each astronaut in each suit performing each movement

    Silent Night

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    Scientific Visualization Using the Flow Analysis Software Toolkit (FAST)

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    Over the past few years the Flow Analysis Software Toolkit (FAST) has matured into a useful tool for visualizing and analyzing scientific data on high-performance graphics workstations. Originally designed for visualizing the results of fluid dynamics research, FAST has demonstrated its flexibility by being used in several other areas of scientific research. These research areas include earth and space sciences, acid rain and ozone modelling, and automotive design, just to name a few. This paper describes the current status of FAST, including the basic concepts, architecture, existing functionality and features, and some of the known applications for which FAST is being used. A few of the applications, by both NASA and non-NASA agencies, are outlined in more detail. Described in the Outlines are the goals of each visualization project, the techniques or 'tricks' used lo produce the desired results, and custom modifications to FAST, if any, done to further enhance the analysis. Some of the future directions for FAST are also described

    CIV Polarization Measurements using a Vacuum Ultraviolet Fabry-Perot Interferometer

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    Marshall Space Flight Center's (MSFC) is developing a Vacuum Ultraviolet (VUV) Fabry-P rot Interferometer that will be launched on a sounding rocket for high throughput, high-cadence, extended field of view CIV (155nm) measurements. These measurements will provide (i) Dopplergrams for studies of waves, oscillations, explosive events, and mass motions through the transition region, and, (ii), polarization measurements to study the magnetic field in the transition region. This paper will describe the scientific goals of the instrument, a brief description of the optics and the polarization characteristics of the VUV Fabry P rot

    Determination of Galaxy Spin Vectors in the Pisces-Perseus Supercluster with the Arecibo Telescope

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    We use HI observations made with the upgraded Arecibo 305M Telescope in August 1998 to obtain accurate spin vector determinations for 54 nearly edge-on galaxies in the Minnesota Automated Plate Scanner Pisces-Perseus Survey (MAPS-PP). We introduce a simple observational technique of determining the sense of rotation for galaxies, even when their HI disks are not fully resolved. We examined the spin vector distribution of these 54 galaxies for evidence of preferential galaxy alignments. We use the Kuiper statistic, a variant of the Kolmogorov--Smirnov statistic, to determine the significance of any anisotropies in the distribution of galaxy spin vectors. The possibility of ``spin vector domains'' is also investigated. We find no significant evidence of preferential galaxy alignments in this sample. However, we show tha t the small sample size places weak limits on the level of galaxy alignments.Comment: 22 pages, 7 figures, Accepted for Publication in Astronomical Journa

    The Origin of the Brightest Cluster Galaxies

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    Most clusters and groups of galaxies contain a giant elliptical galaxy in their centres which far outshines and outweighs normal ellipticals. The origin of these brightest cluster galaxies is intimately related to the collapse and formation of the cluster. Using an N-body simulation of a cluster of galaxies in a hierarchical cosmological model, we show that galaxy merging naturally produces a massive, central galaxy with surface brightness and velocity dispersion profiles similar to observed BCG's. To enhance the resolution of the simulation, 100 dark halos at z=2z=2 are replaced with self-consistent disk+bulge+halo galaxy models following a Tully-Fisher relation using 100000 particles for the 20 largest galaxies and 10000 particles for the remaining ones. This technique allows us to analyze the stellar and dark matter components independently. The central galaxy forms through the merger of several massive galaxies along a filament early in the cluster's history. Galactic cannibalism of smaller galaxies through dynamical friction over a Hubble time only accounts for a small fraction of the accreted mass. The galaxy is a flattened, triaxial object whose long axis aligns with the primordial filament and the long axis of the cluster galaxy distribution agreeing with observed trends for galaxy-cluster alignment.Comment: Revised and accepted in ApJ, 25 pages, 10 figures, online version available at http://www.cita.utoronto.ca/~dubinski/bcg

    Genetic Variation in Mother-Child Acute Seroconverter Pairs from Zambia

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    Objective: To characterize the envelope (env) glycoprotein of HIV-1 in mother-infant pairs (MIP) that underwent near simultaneous or acute-phase seroconversion, we examined the env sequence of the transmitted viruses and compare viral evolution within the pair. Design: Three MIP from a Zambian cohort that seroconverted at the same sampling time were identified and followed longitudinally. Methods: The V1-V5 region of the HIV-1 env gene was sequenced for each sample collected. Phylogenetic and population genetics analyses were carried out to subtype the viruses, estimate relationships among viral genotypes, and compare molecular evolution between the viral populations. Results: Genetic analyses demonstrated a close intrapair relationship between viral sequences from each MIP. Transmission involved several closely related viral genotypes and did not result in a reduction in viral diversity. Amino acid changes were not evenly distributed along env V1-V5 but concentrated in concordant areas within each MIP. Several positions under positive selection were shared between the MIP viruses. Interestingly, selective pressure on the virus was higher in the infants than in the mothers. Conclusions: In contrast to most cases of perinatal transmission of HIV-1 from chronically infected mothers, there is no evidence of a genetic bottleneck in the transmitted viruses in these three instances of acute seroconversion. The longitudinal changes in the amino acids are in similar positions in env for the MIP, suggesting shared evolutionary constrains among the closely related viruses infecting the MIP; such constrains may lead to similar genetic changes in the virus in two different hosts
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