171 research outputs found
Quantum dynamics of a model for two Josephson-coupled Bose--Einstein condensates
In this work we investigate the quantum dynamics of a model for two
single-mode Bose--Einstein condensates which are coupled via Josephson
tunneling. Using direct numerical diagonalisation of the Hamiltonian, we
compute the time evolution of the expectation value for the relative particle
number across a wide range of couplings. Our analysis shows that the system
exhibits rich and complex behaviours varying between harmonic and non-harmonic
oscillations, particularly around the threshold coupling between the
delocalised and self-trapping phases. We show that these behaviours are
dependent on both the initial state of the system as well as regime of the
coupling. In addition, a study of the dynamics for the variance of the relative
particle number expectation and the entanglement for different initial states
is presented in detail.Comment: 15 pages, 8 eps figures, accepted in J. Phys.
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Potential Health Impacts From Range Fires at Aberdeen Proving Ground, Maryland.
This study uses atmospheric dispersion computer models to evaluate the potential for human health impacts from exposure to contaminants that could be dispersed by fires on the testing ranges at Aberdeen Proving Ground, Maryland. It was designed as a screening study and does not estimate actual human health risks. Considered are five contaminants possibly present in the soil and vegetation from past human activities at APG--lead, arsenic, trichloroethylene (TCE), depleted uranium (DU), and dichlorodiphenyltrichloroethane (DDT); and two chemical warfare agents that could be released from unexploded ordnance rounds heated in a range fire--mustard and phosgene. For comparison, dispersion of two naturally occurring compounds that could be released by burning of uncontaminated vegetation--vinyl acetate and 2-furaldehyde--is also examined. Data from previous studies on soil contamination at APG are used in conjunction with conservative estimates about plant uptake of contaminants, atmospheric conditions, and size and frequency of range fires at APG to estimate dispersion and possible human exposure. The results are compared with US Environmental Protection Agency action levels. The comparisons indicate that for all of the anthropogenic contaminants except arsenic and mustard, exposure levels would be at least an order of magnitude lower than the corresponding action levels. Because of the compoundingly conservative nature of the assumptions made, they conclude that the potential for significant human health risks from range fires is low. The authors recommend that future efforts be directed at fire management and control, rather than at conducting additional studies to more accurately estimate actual human health risk from range fires
Attitudes and Opinions About Direct-to-Consumer Genetic Testing in Undergraduate Science Students
Background: There has been exponential growth in the number of direct-to-consumer genetic testing kits sold in the past decade. Consumers utilize direct-to-consumer genetic tests for a number of reasons which include learning about one’s ancestry and potential ways to manage health. Emerging adults tend to be early adopters of new technologies; however, there has been little research regarding the opinions about direct-to-consumer genetic testing in emerging adults.
Methods: Data came from a study conducted in an upper-level biology course focusing on understanding undergraduate science students’ overall experiences with receiving personalized genetic testing results from 23andMe. The present study used data collected at the baseline assessment which assessed their opinions and attitudes about direct-to-consumer genetic testing (N=133).
Results: Over 80% of participants would recommend direct-to-consumer genetic testing options including carrier status reports, DNA ancestry reports, wellness reports, and trait reports to others. However, participants were not as confident that others would be able to accurately interpret their test results. Additionally, more than two-thirds of the participants stated that they would ask a healthcare provider to help interpret their personalized genetic test results.
Conclusions: Participants lack confidence in both their ability to interpret their own results and others to interpret their results. It is important for direct-to-consumer genetic testing companies to educate consumers before providing results in order to minimize potential harms due to misinterpretation of results. Further research is needed to assess motivations to participate in direct-to-consumer genetic testing, impact of testing, and understanding of genetic testing results in emerging adults.https://scholarscompass.vcu.edu/gradposters/1124/thumbnail.jp
Diferentes épocas de colheita, secagem e armazenamento na qualidade de grãos de trigo comum e duro
Evaluation of reduction in egg shedding of gastrointestinal nematodes in cattle following administration of anthelmintics
Influences of H on the Adsorption of a Single Ag Atom on Si(111)-7 × 7 Surface
The adsorption of a single Ag atom on both clear Si(111)-7 × 7 and 19 hydrogen terminated Si(111)-7 × 7 (hereafter referred as 19H-Si(111)-7 × 7) surfaces has been investigated using first-principles calculations. The results indicated that the pre-adsorbed H on Si surface altered the surface electronic properties of Si and influenced the adsorption properties of Ag atom on the H terminated Si surface (e.g., adsorption site and bonding properties). Difference charge density data indicated that covalent bond is formed between adsorbed Ag and H atoms on 19H-Si(111)-7 × 7 surface, which increases the adsorption energy of Ag atom on Si surface
Study of the aging of fermented of yacon (Smallanthus sonchifolius) and sensory profile and acceptance
Xylella fastidiosa gene expression analysis by DNA microarrays
Xylella fastidiosa genome sequencing has generated valuable data by identifying genes acting either on metabolic pathways or in associated pathogenicity and virulence. Based on available information on these genes, new strategies for studying their expression patterns, such as microarray technology, were employed. A total of 2,600 primer pairs were synthesized and then used to generate fragments using the PCR technique. The arrays were hybridized against cDNAs labeled during reverse transcription reactions and which were obtained from bacteria grown under two different conditions (liquid XDM2 and liquid BCYE). All data were statistically analyzed to verify which genes were differentially expressed. In addition to exploring conditions for X. fastidiosa genome-wide transcriptome analysis, the present work observed the differential expression of several classes of genes (energy, protein, amino acid and nucleotide metabolism, transport, degradation of substances, toxins and hypothetical proteins, among others). The understanding of expressed genes in these two different media will be useful in comprehending the metabolic characteristics of X. fastidiosa, and in evaluating how important certain genes are for the functioning and survival of these bacteria in plants
Early Planet Formation in Embedded Disks (eDisk). I. Overview of the Program and First Results
We present an overview of the Large Program, ``Early Planet Formation in
Embedded Disks (eDisk)'', conducted with the Atacama Large
Millimeter/submillimeter Array (ALMA). The ubiquitous detections of
substructures, particularly rings and gaps, in protoplanetary disks around T
Tauri stars raise the possibility that at least some planet formation may have
already started during the embedded stages of star formation. In order to
address exactly how and when planet formation is initiated, the program focuses
on searching for substructures in disks around 12 Class 0 and 7 Class I
protostars in nearby (200 pc) star-forming regions through 1.3 mm continuum
observations at a resolution of au (0.04"). The initial results show
that the continuum emission, mostly arising from dust disks around the sample
protostars, has relatively few distinctive substructures, such as rings and
spirals, in marked contrast to Class II disks. The dramatic difference may
suggest that substructures quickly develop in disks when the systems evolve
from protostars to Class II sources or alternatively that high optical depth of
the continuum emission could obscure internal structures. Kinematic information
obtained through CO isotopologue lines and other lines reveals the presence of
Keplerian disks around protostars, providing us with crucial physical
parameters, in particular, the dynamical mass of the central protostars. We
describe the background of the eDisk program, the sample selection and their
ALMA observations, the data reduction, and also highlight representative
first-look results.Comment: This is a publication of a series of eDisk ALMA large program
first-look paper
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