3,432 research outputs found
Virus taxonomy: the database of the International Committee on Taxonomy of Viruses (ICTV)
The International Committee on Taxonomy of Viruses (ICTV) is charged with the task of developing, refining, and maintaining a universal virus taxonomy. This task encompasses the classification of virus species and higher-level taxa according to the genetic and biological properties of their members; naming virus taxa; maintaining a database detailing the currently approved taxonomy; and providing the database, supporting proposals, and other virus-related information from an open-access, public web site. The ICTV web site (http://ictv.global) provides access to the current taxonomy database in online and downloadable formats, and maintains a complete history of virus taxa back to the first release in 1971. The ICTV has also published the ICTV Report on Virus Taxonomy starting in 1971. This Report provides a comprehensive description of all virus taxa covering virus structure, genome structure, biology and phylogenetics. The ninth ICTV report, published in 2012, is available as an open-access online publication from the ICTV web site. The current, 10th report (http://ictv.global/report/), is being published online, and is replacing the previous hard-copy edition with a completely open access, continuously updated publication. No other database or resource exists that provides such a comprehensive, fully annotated compendium of information on virus taxa and taxonomy
Asymmetric Berry-Phase Interference Patterns in a Single-Molecule Magnet
A Mn4 single-molecule magnet displays asymmetric Berry-phase interference
patterns in the transverse-field (HT) dependence of the magnetization tunneling
probability when a longitudinal field (HL) is present, contrary to symmetric
patterns observed for HL=0. Reversal of HL results in a reflection of the
transverse-field asymmetry about HT=0, as expected on the basis of the
time-reversal invariance of the spin-orbit Hamiltonian which is responsible for
the tunneling oscillations. A fascinating motion of Berry-phase minima within
the transverse-field magnitude-direction phase space results from a competition
between noncollinear magnetoanisotropy tensors at the two distinct Mn sites.Comment: 4 double-column page
Purebred Sires Effect Herd Improvement
The real worth of a sire for the dairy herd can be established only when production records of the progeny are available for comparison with those of the preceding generation. A study of the following three sires which have been in service in the University of Nebraska dairy herd should be of interest to the Nebraska dairyman wishing to improve his own herd. This experiment indicates that the apparently high cost of a good herd sire is more than outweighed by the increase in the value of the progeny
Microcavities Using Holey Fibers
Vacuum compatible microcavities consisting of microstructured holey fibers
and separate end mirrors have been constructed and tested. These devices
exhibit excellent transverse mode confinement and the ability to control the
percentage of power guided outside of the fiber core. As a result, these
devices may be a useful tool for enhancing the interaction between light and an
atomic medium
More Evidence for a Distribution of Tunnel Splittings in Mn-acetate
In magnetic fields applied parallel to the anisotropy axis, the magnetization
of Mn has been measured in response to a field that is swept back and
forth across the resonances corresponding to steps . The fraction
of molecules remaining in the metastable well after each sweep through the
resonance is inconsistent with expectations for an ensemble of identical
molecules. The data are consistent instead with the presence of a broad
distribution of tunnel splittings. A very good fit is obtained for a Gaussian
distribution of the second-order anisotropy tunneling parameter . We show that dipolar shuffling is a negligible effect which cannot
explain our data.Comment: minor corrections (PACS nos, signs in Fig. 2
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