2,380 research outputs found
Movements of Channel Catfish and Flathead Catfish in Beaver Reservoir, Northwest Arkansas
A total of 497 channel catfish, Ictalurus punctatus, and flathead catfish, Pylodictis olivaris. were tagged in Beaver Reservoir during two November-April tagging periods (1967-68 and 1968-69); total recaptures were 9.5 and 11.7% respectively. The longest time between tagging and recapture was 1622 days (4.4 years) for channel catfish and 494 days (1.4 years) for flathead catfish. The longest distances traveled were 43.1 km by a channel catfish and 44.3 km by a flathead catfish. Fisherman returns indicated that catfish were caught primarily from April through July. The many recaptures, even after long periods, within 1.6 km of the tagging point, suggested that fish moved little, or had homing tendencies. Captures of fish in trap nets indicated that rainfall and inflow possibly stimulated movements of channel catfish during the winter and early spring
Methodological Issues in Multistage Genome-Wide Association Studies
Because of the high cost of commercial genotyping chip technologies, many
investigations have used a two-stage design for genome-wide association
studies, using part of the sample for an initial discovery of ``promising''
SNPs at a less stringent significance level and the remainder in a joint
analysis of just these SNPs using custom genotyping. Typical cost savings of
about 50% are possible with this design to obtain comparable levels of overall
type I error and power by using about half the sample for stage I and carrying
about 0.1% of SNPs forward to the second stage, the optimal design depending
primarily upon the ratio of costs per genotype for stages I and II. However,
with the rapidly declining costs of the commercial panels, the generally low
observed ORs of current studies, and many studies aiming to test multiple
hypotheses and multiple endpoints, many investigators are abandoning the
two-stage design in favor of simply genotyping all available subjects using a
standard high-density panel. Concern is sometimes raised about the absence of a
``replication'' panel in this approach, as required by some high-profile
journals, but it must be appreciated that the two-stage design is not a
discovery/replication design but simply a more efficient design for discovery
using a joint analysis of the data from both stages. Once a subset of
highly-significant associations has been discovered, a truly independent
``exact replication'' study is needed in a similar population of the same
promising SNPs using similar methods.Comment: Published in at http://dx.doi.org/10.1214/09-STS288 the Statistical
Science (http://www.imstat.org/sts/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Problem-Based Learning in Mathematics
A teacher of mathematics has a great opportunity. If he fills his allotted time with drilling his students in routine operations, he kills their interest, hampers their intellectual development, and misuses his opportunity. But if he challenges the curiosity of his students by setting them problems proportionate to their knowledge and helps them to solve their problems with stimulating questions, he may give them a taste for, and some independent means of, independent thinking
Modified Lautenbach technique in the treatment of an open infected non-union of the clavicle—a case report
Quantum fields, cosmological constant and symmetry doubling
Energy-parity has been introduced by Kaplan and Sundrum as a protective
symmetry that suppresses matter contributions to the cosmological constant
[KS05]. It is shown here that this symmetry, schematically Energy --> - Energy,
arises in the Hilbert space representation of the classical phase space
dynamics of matter. Consistently with energy-parity and gauge symmetry, we
generalize the Liouville operator and allow a varying gauge coupling, as in
"varying alpha" or dilaton models. In this model, classical matter fields can
dynamically turn into quantum fields (Schroedinger picture), accompanied by a
gauge symmetry change -- presently, U(1) --> U(1) x U(1). The transition
between classical ensemble theory and quantum field theory is governed by the
varying coupling, in terms of a one-parameter deformation of either limit.
These corrections introduce diffusion and dissipation, leading to decoherence.Comment: Replaced by published version, no change in contents - Int. J. Theor.
Phys. (2007
Zero temperature string breaking in lattice quantum chromodynamics
The separation of a heavy quark and antiquark pair leads to the formation of
a tube of flux, or "string", which should break in the presence of light
quark-antiquark pairs. This expected zero-temperature phenomenon has proven
elusive in simulations of lattice QCD. We study mixing between the string state
and the two-meson decay channel in QCD with two flavors of dynamical sea
quarks. We confirm that mixing is weak and find that it decreases at level
crossing. While our study does not show direct effects of internal quark loops,
our results, combined with unitarity, give clear confirmation of string
breaking.Comment: 20 pages, 7 figures. With small clarifications and two additions to
references. Submitted to Phys. Rev.
Maxwell-Chern-Simons Vortices and Holographic Superconductors
We investigate probe limit vortex solutions of a charged scalar field in
Einstein-Maxwell theory in 3+1 dimensions, for an asymptotically AdS
Schwarzschild black hole metric with the addition of an axionic coupling to the
Maxwell field. We show that the inclusion of such a term, together with a
suitable potential for the axion field, can induce an effective Chern-Simons
term on the 2+1 dimensional boundary. We obtain numerical solutions of the
equations of motion and find Maxwell-Chern-Simons like magnetic vortex
configurations, where the magnetic field profile varies with the size of the
effective Chern-Simons coupling. The axion field has a non-trivial profile
inside the AdS bulk but does not condense at spatial infinity.Comment: 17 pages, 5 figures, version accepted for publication in JHE
The RING-CH ligase K5 antagonizes restriction of KSHV and HIV-1 particle release by mediating ubiquitin-dependent endosomal degradation of tetherin
Tetherin (CD317/BST2) is an interferon-induced membrane protein that inhibits the release of diverse enveloped viral particles. Several mammalian viruses have evolved countermeasures that inactivate tetherin, with the prototype being the HIV-1 Vpu protein. Here we show that the human herpesvirus Kaposi's sarcoma-associated herpesvirus (KSHV) is sensitive to tetherin restriction and its activity is counteracted by the KSHV encoded RING-CH E3 ubiquitin ligase K5. Tetherin expression in KSHV-infected cells inhibits viral particle release, as does depletion of K5 protein using RNA interference. K5 induces a species-specific downregulation of human tetherin from the cell surface followed by its endosomal degradation. We show that K5 targets a single lysine (K18) in the cytoplasmic tail of tetherin for ubiquitination, leading to relocalization of tetherin to CD63-positive endosomal compartments. Tetherin degradation is dependent on ESCRT-mediated endosomal sorting, but does not require a tyrosine-based sorting signal in the tetherin cytoplasmic tail. Importantly, we also show that the ability of K5 to substitute for Vpu in HIV-1 release is entirely dependent on K18 and the RING-CH domain of K5. By contrast, while Vpu induces ubiquitination of tetherin cytoplasmic tail lysine residues, mutation of these positions has no effect on its antagonism of tetherin function, and residual tetherin is associated with the trans-Golgi network (TGN) in Vpu-expressing cells. Taken together our results demonstrate that K5 is a mechanistically distinct viral countermeasure to tetherin-mediated restriction, and that herpesvirus particle release is sensitive to this mode of antiviral inhibition
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