7,117 research outputs found
USSR Space Life Sciences Digest
Research in exobiology, life sciences technology, space biology, and space medicine and physiology, primarily using data gathered on the Salyut 6 orbital space station, is reported. Methods for predicting, diagnosing, and preventing the effects of weightlessness are discussed. Psychological factors are discussed. The effects of space flight on plants and animals are reported. Bioinstrumentation advances are noted
Restoration of eucalypt grassy woodland: effects of experimental interventions on ground-layer vegetation
We report on the effects of broad-scale restoration treatments on the ground layer of eucalypt grassy woodland in south-eastern Australia. The experiment was conducted in two conservation reserves from which livestock grazing had previously been removed. Changes in biomass, species diversity, ground-cover attributes and life-form were analysed over a 4-year period in relation to the following experimental interventions: (1) reduced kangaroo density, (2) addition of coarse woody debris and (3) fire (a single burn). Reducing kangaroo density doubled total biomass in one reserve, but no effects on exotic biomass, species counts or ground cover attributes were observed. Coarse woody debris also promoted biomass, particularly exotic annual forbs, as well as plant diversity in one of the reserves. The single burn reduced biomass, but changed little else. Overall, we found the main driver of change to be the favourable growth seasons that had followed a period of drought. This resulted in biomass increasing by 67%, (mostly owing to the growth of perennial native grasses), whereas overall native species counts increased by 18%, and exotic species declined by 20% over the 4-year observation period. Strategic management of grazing pressure, use of fire where biomass has accumulated and placement of coarse woody debris in areas of persistent erosion will contribute to improvements in soil and vegetation condition, and gains in biodiversity, in the future.Funding and in-kind logistic support for this project was
provided by the ACT Government as part of an Australian Research
Council Linkage Grant (LP0561817; LP110100126). Drafts of the
manuscript were read by Saul Cunningham and Ben Macdonald
The SERENDIP 2 SETI project: Current status
Over the past 30 years, interest in extraterrestrial intelligence has progressed from philosophical discussion to rigorous scientific endeavors attempting to make contact. Since it is impossible to assess the probability of success and the amount of telescope time needed for detection, Search for Extraterrestrial Intelligence (SETI) Projects are plagued with the problem of attaining the large amounts of time needed on the world's precious few large radio telescopes. To circumvent this problem, the Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations (SERENDIP) instrument operates autonomously in a piggyback mode utilizing whatever observing plan is chosen by the primary observer. In this way, large quantities of high-quality data can be collected in a cost-effective and unobtrusive manner. During normal operations, SERENDIP logs statistically significant events for further offline analysis. Due to the large number of terrestrial and near-space transmitters on earth, a major element of the SERENDIP project involves identifying and rejecting spurious signals from these sources. Another major element of the SERENDIP Project (as well as most other SETI efforts) is detecting extraterrestrial intelligence (ETI) signals. Events selected as candidate ETI signals are studied further in a targeted search program which utilizes between 24 to 48 hours of dedicated telescope time each year
Infusing Problem-Based Learning (PBL) Into Science Methods Courses Across Virginia
This article outlines the results of a collaborative study of the effects of infusing problem-based learning (PBL) into K-12 science methods courses across four universities in Virginia. Changes in pre-service teachers\u27 attitudes surrounding science teaching were measured before and after completing a science methods course in which they experienced PBL first-hand as participants, and then practiced designing their own PBL units for use in their future classrooms. The results indicate that exposure to PBL enhances pre-service teachers\u27 knowledge of inquiry methods and self-efficacy in teaching science
Bragg Spectroscopy of Vortex Lattices in Bose-Einstein condensates
We have measured the velocity field of a vortex lattice within a sodium
Bose-Einstein condensate using Bragg scattering. The phase gradient of the
macroscopic wavefunction was mapped into the spatial structure of the
diffracted atom cloud, allowing for single shot measurement of the rotation
parameters. A combination of spectral and spatial information yields a complete
description of the superfluid flow, coarse-grained over the lattice structure,
including direct and independent measurements of the rate and sense of
rotation. Signatures of the microscopic quantum rotation have also been
observed.Comment: 5 pages, 5 Figures, A movie built from the CM data is available in
our Webpage: http://www.physics.gatech.edu/chandra/index.htm; added Fig.5
presents new data, showing signatures of the microscopic vortex structure in
the diffracted clou
Modeling Solar Lyman Alpha Irradiance
Solar Lyman alpha irradiance is estimated from various solar indices using linear regression analyses. Models developed with multiple linear regression analysis, including daily values and 81-day running means of solar indices, predict reasonably well both the short- and long-term variations observed in Lyman alpha. It is shown that the full disk equivalent width of the He line at 1083 nm offers the best proxy for Lyman alpha, and that the total irradiance corrected for sunspot effect also has a high correlation with Lyman alpha
Vortices in fermion droplets with repulsive dipole-dipole interactions
Vortices are found in a fermion system with repulsive dipole-dipole
interactions, trapped by a rotating quasi-two-dimensional harmonic oscillator
potential. Such systems have much in common with electrons in quantum dots,
where rotation is induced via an external magnetic field. In contrast to the
Coulomb interactions between electrons, the (externally tunable) anisotropy of
the dipole-dipole interaction breaks the rotational symmetry of the
Hamiltonian. This may cause the otherwise rotationally symmetric exact
wavefunction to reveal its internal structure more directly.Comment: 5 pages, 5 figure
Expert advice and political choice in constructing European banking union
International actors promoted the transfer of regulatory authority and financial resources from national governments to the European Union (EU) in the context of establishing the prerequisites for financial stability in Europe through banking union. It was supplied, however, by a political process that kept significant resources in resolution and deposit insurance largely in national hands. This article examines the politics behind those decisions, and how the hybrid of European and national competences affects bank regulation and financial stability in the EU. It concludes that the tension between strong EU supervisory powers and weak capacity to deal with insolvent institutions will persist
Bending-wave Instability of a Vortex Ring in a Trapped Bose-Einstein Condensate
Based on a velocity formula derived by matched asymptotic expansion, we
investigate the dynamics of a circular vortex ring in an axisymmetric
Bose-Einstein condensate in the Thomas-Fermi limit. The trajectory for an
axisymmetrically placed and oriented vortex ring is entirely determined,
revealing that the vortex ring generally precesses in condensate. The linear
instability due to bending waves is investigated both numerically and
analytically. General stability boundaries for various perturbed wavenumbers
are computed. In particular, the excitation spectrum and the absolutely stable
region for the static ring are analytically determined.Comment: 4 pages, 4 figure
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