638 research outputs found
COST TIST - European Research Cooperation in Telecommunications and Information Science and Technology
In 1971, the Ministerial Conference of the European Union opened for 19 European countries the possibility of cooperation in the field of scientific and technical research, by formally establishing the framework of COST (Cooperation Scientifique et Technique).COST-TIST covers all COST activities in the field of telecommunications and information science and technology, from fundamental research to services and applications. TIST Actions have successfully contributed to the aims of the European Research Area by bringing a large set of national, industrial, and university research in the field together into a common framework of research objective
Photoconductive switching of a high-voltage spark gap
We have demonstrated photoconductive switching of a gas-filled spark gap. A femtosecond Ti:sapphire laser was focused in a 1 mm spark gap biased at 4.5 kV. There is a clear transition between triggered operation, when only part of the path between the electrodes is ionized, and photoconductive switching, when the entire length of the gap is ionized directly by the laser. The measured standard deviation of the time fluctuations between the rising edge of the transmitted electrical pulse and the laser was less than 15 ps
Intruder level and deformation in the SD-pair shell model
The influence of the intruder level on nuclear deformation is studied within
the framework of the nucleon-pair shell model truncated to an SD-pair subspace.
The results suggest that the intruder level has a tendency to soften the
deformation and plays an important role in determining the onset of rotational
behavior.Comment: 2 input TeX files, 2 figures, submitted to Phys. Lett.
Effective operators from exact many-body renormalization
We construct effective two-body Hamiltonians and E2 operators for the p-shell
by performing ab initio no-core shell model (NCSM) calculations
for A=5 and A=6 nuclei and explicitly projecting the many-body Hamiltonians and
E2 operator onto the space. We then separate the effective E2
operator into one-body and two-body contributions employing the two-body
valence cluster approximation. We analyze the convergence of proton and neutron
valence one-body contributions with increasing model space size and explore the
role of valence two-body contributions. We show that the constructed effective
E2 operator can be parametrized in terms of one-body effective charges giving a
good estimate of the NCSM result for heavier p-shell nuclei.Comment: 9 pages, 8 figure
Strong Coupling Correction in Superfluid He in Aerogel
Effects of impurity scatterings on the strong coupling (SC) contribution,
stabilizing the ABM (axial) pairing state, to the quartic term of the
Ginzburg-Landau (GL) free energy of superfluid He are theoretically studied
to examine recent observations suggestive of an anomalously small SC effect in
superfluid He in aerogels. To study the SC corrections, two approaches are
used. One is based on a perturbation in the short-range repulsive interaction,
and the other is a phenomenological approach used previously for the bulk
liquid by Sauls and Serene [Phys.Rev.B 24, 183 (1981)]. It is found that the
impurity scattering favors the BW pairing state and shrinks the region of the
ABM pairing state in the T-P phase diagram. In the phenomenological approach,
the resulting shrinkage of the ABM region is especially substantial and, if
assuming an anisotropy over a large scale in aerogel, leads to justifying the
phase diagrams determined experimentally.Comment: 19 pages, 9 figures, Accepted for publication in Phys. Rev.
Discovery of a dsRNA virus infecting the marine photosynthetic protist Micromonas pusilla
AbstractWe report the isolation of the first double-stranded (ds) RNA virus in the family Reoviridae that infects a protist (microalga Micromonas pusilla, Prasinophyceae). The dsRNA genome was composed of 11 segments ranging between 0.8 and 5.8 kb, with a total size of approximately 25.5 kb. The virus (MpRNAV-01B) could not be assigned to the genus level because host type, genome size, and number of segments smaller than 2 kb did not correspond to either of the two existing 11-segmented dsRNA genera Rotavirus and Aquareovirus. MpRNAV-01B has a particle size of 65–80 nm, a narrow host range, a latent period of 36 h, and contains five major proteins (120, 95, 67, 53, and 32 kDa). MpRNAV-01B was stable to freeze–thawing, resistant to chloroform, ether, nonionic detergents, chelating and reducing agents. The virus was inactivated at temperatures above 35 °C and by ionic detergent, ethanol, acetone, and acidic conditions (pH 2–5)
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