90 research outputs found
Effects of category-relevance, retention measure, and category-affiliation upon retention of the aging
The present investigation represents an attempt to further explore several parameters of short-term memory as a function of the relevance of appropriateness of the verbal materials utilized. It is the author\u27s contention that due to changing patterns of interests and experiences accompanying chronological aging, certain types of verbal material vary with respect to their relevance for use with aging populations. In regard to parameters of short-term memory, the present study contains provisions for exploring efficiency of retention as a function of the retention measure; and category•affiliated as opposed to randomly-selected words. A more complete and integrated formulation is presented in the following chapter
Improved Parameters and New Lensed Features for Q0957+561 from WFPC2 Imaging
New HST WFPC2 observations of the lensed double QSO 0957+561 will allow
improved constraints on the lens mass distribution and hence will improve the
derived value of H. We first present improved optical positions and
photometry for the known components of this lens. The optical separation
between the A and B quasar images agrees with VLBI data at the 10 mas level,
and the optical center of the primary lensing galaxy G1 coincides with the VLBI
source G' to within 10 mas. The best previous model for this lens (Grogin and
Narayan 1996) is excluded by these data and must be reevaluated.
Several new resolved features are found within 10\arcsec of G1, including an
apparent fold arc with two bright knots. Several other small galaxies are
detected, including two which may be multiple images of each other. We present
positions and crude photometry of these objects.Comment: 7 pages including 2 postscript figures, LaTeX, emulateapj style. Also
available at
http://www.astro.lsa.umich.edu:80/users/philf/www/papers/list.htm
Detection of Lens Candidates for the Double QSO Q2345+007
Luminous objects associated with the 7.06\arcsec\ separation double quasar
Q2345+007 have, until now, escaped detection. In this letter we present the
results of the deepest known imaging of the region surrounding the quasar. The
total exposure times were 47600 seconds in B (101 frames) and 32160 seconds
in R (82 frames). The frames came from CFHT, CTIO, and KPNO. We detect a B
= 25.0 mag galaxy (B -- R = 0.5 mag) in close proximity to the fainter QSO
image, possibly at given by several absorption features in the QSO
spectra. Furthermore, there is a 2.9 enhancement in the number density
of faint galaxies ( B , B R ) near the
quasar and another 3.1 enhancement further away. These discoveries
support the hypothesis that Q2345+007 is being lensed by one or more distant
mass concentrations and may imply that compact ``clusters'' already exist at
early epochs. We discuss several lens models for the system and the
cosmological implications.Comment: (uuencoded compressed postscript
Detection of weak gravitational lensing distortions of distant galaxies by cosmic dark matter at large scales
Most of the matter in the universe is not luminous and can be observed
directly only through its gravitational effect. An emerging technique called
weak gravitational lensing uses background galaxies to reveal the foreground
dark matter distribution on large scales. Light from very distant galaxies
travels to us through many intervening overdensities which gravitationally
distort their apparent shapes. The observed ellipticity pattern of these
distant galaxies thus encodes information about the large-scale structure of
the universe, but attempts to measure this effect have been inconclusive due to
systematic errors. We report the first detection of this ``cosmic shear'' using
145,000 background galaxies to reveal the dark matter distribution on angular
scales up to half a degree in three separate lines of sight. The observed
angular dependence of this effect is consistent with that predicted by two
leading cosmological models, providing new and independent support for these
models.Comment: 18 pages, 5 figures: To appear in Nature. (This replacement fixes tex
errors and typos.
A Job is Not a Hobby: The Judicial Revival of Corporate Paternalism and its Problematic Implications
Australia\u27s health 1992 : the third biennial report of the Australian Institute of Health and Welfare
Australia\u27s Health is the most comprehensive and authoritative source of national information on health in Australia. Australia\u27s Health is published mid-year in even-numbered years and provides national statistics and related information that form a record of health status, service provision and expenditure in Australia
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
Assembling the Marine Metagenome, One Cell at a Time
The difficulty associated with the cultivation of most microorganisms and the complexity of natural microbial assemblages, such as marine plankton or human microbiome, hinder genome reconstruction of representative taxa using cultivation or metagenomic approaches. Here we used an alternative, single cell sequencing approach to obtain high-quality genome assemblies of two uncultured, numerically significant marine microorganisms. We employed fluorescence-activated cell sorting and multiple displacement amplification to obtain hundreds of micrograms of genomic DNA from individual, uncultured cells of two marine flavobacteria from the Gulf of Maine that were phylogenetically distant from existing cultured strains. Shotgun sequencing and genome finishing yielded 1.9 Mbp in 17 contigs and 1.5 Mbp in 21 contigs for the two flavobacteria, with estimated genome recoveries of about 91% and 78%, respectively. Only 0.24% of the assembling sequences were contaminants and were removed from further analysis using rigorous quality control. In contrast to all cultured strains of marine flavobacteria, the two single cell genomes were excellent Global Ocean Sampling (GOS) metagenome fragment recruiters, demonstrating their numerical significance in the ocean. The geographic distribution of GOS recruits along the Northwest Atlantic coast coincided with ocean surface currents. Metabolic reconstruction indicated diverse potential energy sources, including biopolymer degradation, proteorhodopsin photometabolism, and hydrogen oxidation. Compared to cultured relatives, the two uncultured flavobacteria have small genome sizes, few non-coding nucleotides, and few paralogous genes, suggesting adaptations to narrow ecological niches. These features may have contributed to the abundance of the two taxa in specific regions of the ocean, and may have hindered their cultivation. We demonstrate the power of single cell DNA sequencing to generate reference genomes of uncultured taxa from a complex microbial community of marine bacterioplankton. A combination of single cell genomics and metagenomics enabled us to analyze the genome content, metabolic adaptations, and biogeography of these taxa
The Core and Accessory Genomes of Burkholderia pseudomallei: Implications for Human Melioidosis
Natural isolates of Burkholderia pseudomallei (Bp), the causative agent of melioidosis, can exhibit significant ecological flexibility that is likely reflective of a dynamic genome. Using whole-genome Bp microarrays, we examined patterns of gene presence and absence across 94 South East Asian strains isolated from a variety of clinical, environmental, or animal sources. 86% of the Bp K96243 reference genome was common to all the strains representing the Bp “core genome”, comprising genes largely involved in essential functions (eg amino acid metabolism, protein translation). In contrast, 14% of the K96243 genome was variably present across the isolates. This Bp accessory genome encompassed multiple genomic islands (GIs), paralogous genes, and insertions/deletions, including three distinct lipopolysaccharide (LPS)-related gene clusters. Strikingly, strains recovered from cases of human melioidosis clustered on a tree based on accessory gene content, and were significantly more likely to harbor certain GIs compared to animal and environmental isolates. Consistent with the inference that the GIs may contribute to pathogenesis, experimental mutation of BPSS2053, a GI gene, reduced microbial adherence to human epithelial cells. Our results suggest that the Bp accessory genome is likely to play an important role in microbial adaptation and virulence
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