918 research outputs found
A note on the evaluation of a beta-casein variant in bovine breeds by allele-specific PCR and relevance to β-casomorphin
peer-reviewedThis work was supported by Enterprise Ireland and by a Teagasc Walsh fellowship to A.F. Keating.Two genetic variants of the bovine β-casein gene (A1 and B) encode a histidine residue at codon 67, resulting in potential liberation of a bioactive peptide, β-casomorphin, upon digestion. An allele-specific PCR (AS-PCR) was evaluated to distinguish between the β-casomorphin-releasing variants (A1 and B) and the non-releasing variants. AS-PCR successfully distinguished β-casein variants in 41 of 42 animals as confirmed by sequence analysis. Overall, while the incidence of the homozygous A1 and B animals (i.e., homozygous for the histidine residue; 21.4%) was lower than that for animals without the histidine residue (30.9% respectively), 69% of animals carried at least one allele for the histidine residue at codon 67.Teagasc Walsh Fellowship ProgrammeEnterprise Irelan
The Refractive Index of Curved Spacetime II: QED, Penrose Limits and Black Holes
This work considers the way that quantum loop effects modify the propagation
of light in curved space. The calculation of the refractive index for scalar
QED is reviewed and then extended for the first time to QED with spinor
particles in the loop. It is shown how, in both cases, the low frequency phase
velocity can be greater than c, as found originally by Drummond and Hathrell,
but causality is respected in the sense that retarded Green functions vanish
outside the lightcone. A "phenomenology" of the refractive index is then
presented for black holes, FRW universes and gravitational waves. In some
cases, some of the polarization states propagate with a refractive index having
a negative imaginary part indicating a potential breakdown of the optical
theorem in curved space and possible instabilities.Comment: 62 pages, 14 figures, some signs corrected in formulae and graph
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Petrologic and oxygen-isotopic investigations of eucritic and anomalous mafic achondrites
The most common asteroidal igneous meteorites are eucrite-type basalts and gabbros rocks composed of ferroan pigeonite and augite, calcic plagioclase, silica, ilmenite, troilite, Ca-phosphate, chromite and Fe-metal. These rocks are thought to have formed on a single asteroid along with howardites and diogenites (HEDs). However, Northwest Africa (NWA) 011 is mineralogically identical to eucrites, but has an O-isotopic composition distinct from them and was derived from a different asteroid. Modern analyses with higher precision have shown that some eucrites have smaller O-isotopic differences that are nevertheless well-resolved from the group mean
Net and Tension infiltration effects of PAM in furrow irrigation
The history and fundamental aspects
of polyacrylamide (PAM)-use
in furrow irrigation water has been
covered in depth in several publications
(Barvenik, 1994; Lentz et al.,
1992; Lentz and Sojka, 1994a; Lentz,
1995; Lentz and Sojka, 1996; Sojka
and Lentz, 1996; Sojka and Lentz,
1997). In agriculture, the two greatest
benefits associated with this practice
are the near elimination of furrow
erosion and substantial increases
in infiltration compared to untreated
water. The large erosion reduction
has both on-site and downstream economic
and environmental benefits
(Agassi et al., 1995 ; Bahr et al., 1996;
Bahr and Steiber, 1996; Lentz et al.,
1992; Lentz, 1995; Lentz and Sojka,
1996; McCutchan eta!., 1993; Singh
et al., 1996; Sojka and Lentz, 1993;
Sojka and Lentz, 19946; Sojka et al.,
1995; Sojka and Lentz, 1997). Infiltration
effects are a substantial aspect
of these benefits, but have been less
thoroughly considered in data reported
to date
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Development of a surface-specific, anti-weathering stone preservative treatment
We are testing an anti-weathering preservation strategy that is specific to limestone surfaces. The strategy involves the application of a mineral-specific, bifunctional, passivating/coupling agent that binds to both the limestone surface and to the consolidating inorganic polymer matrix. The sol-gel based reactions form composite materials with desirable conservation and anti-weathering properties. We present the results of our efforts, the highlights of which are: (1) scanning probe microscopy of moisture-free calcite crystals treated with the trisilanol form of silylalkylaminocarboxylate (SAAC), reveals porous agglomerates that offer no significant resistance to the mild leaching action of deionized water. When the crystals are further consolidated with a silica-based consolidant (A2**), no dissolution is seen although the positive role of the passivant molecule is not yet delineated. (2) Modulus of rupture tests on limestone cores treated with an aminoalkylsilane (AEAPS) and A2** showed a 25-35% increase in strength compared to the untreated samples. (3) Environmental scanning electron microscopy of treated limestone subjected to a concentrated acid attack showed degradation of the surface except in areas where thick layers of the consolidant were deposited
Entanglement between a qubit and the environment in the spin-boson model
The quantitative description of the quantum entanglement between a qubit and
its environment is considered. Specifically, for the ground state of the
spin-boson model, the entropy of entanglement of the spin is calculated as a
function of , the strength of the ohmic coupling to the environment,
and , the level asymmetry. This is done by a numerical
renormalization group treatment of the related anisotropic Kondo model. For
, the entanglement increases monotonically with , until it
becomes maximal for . For fixed , the entanglement
is a maximum as a function of for a value, .Comment: 4 pages, 3 figures. Shortened version restricted to groundstate
entanglemen
Effect of Hydrologic Restoration on the Habitat of the Cape Sable Seaside Sparrow, 2008 – Final Report
This document summarizes the activities that were accomplished in 2008, the sixth year of the research project “Effect of hydrologic restoration on the habitat of the Cape Sable seaside sparrow”, a collaborative effort among the US Army Corps of Engineers, Everglades National Park, Florida International University, and the US Geological Survey (Florida Integrated Science Center). The major activities in 2008 included field work, data analysis, and presentations. Jay Sah presented the results of 6th year field work at the Cape Sable seaside sparrow (CSSS) Fire Meeting 2008, held on December 2-3 at the Krome Center, Homestead, Florida. In the same meeting, Mike Ross presented results from a related USFWS-funded project on encroachment pattern of woody plants in Cape Sable seaside sparrow habitat
Polyacrylamide effects on infiltration in irrigated agriculture
Using polyacrylamide (PAM) following the NRCS conservation practice standard
increases infiltration in furrow irrigation. PAM at 10 g in-' (10 ppm) during water advance
nearly precludes detachment and transport of soil in furrows. If any sediment is entrained in the
flow, it is readily flocculated in the presence of PAM and settles to the furrow-bottom in loose pervious
structures. It was hypothesized that depositional surface seals that block pores are reduced or
made more permeable with PAM. On Portneuf silt beams (coarse-silty, mixed, superactive,
Durinodic Xeric Haplocalcid) furrow irrigation net infiltration increased 15%. Net increases on
finer textured soils were generally higher. Furrow streams containing more than 5 g L (5,000
ppm) sediment reduced infiltration and infiltration rate more than fivefold compared to streams
of clean water. Tension infiltrometry confirmed that PAM's maintenance of open pores to the furrow
surface provides the infiltration increase mechanism. Infiltration rates at 40 and 100 min
(1.6 and 3.9 inches) tension in PAM-treated furrows were double the rates of control furrows.
Recirculating infiltrometer data showed a 30% infiltration increase with PAM use and infiltration
was inversely related to maximum sediment concentration in the flow. Furrow inflow of
45 L min-1 (12 gal min-1 ) with PAM treatment decreased stream advance time 13% while reducing
sediment loss 76% compared to untreated 23 L min-1 (6 gal min-1) inflows. Use of
PAM in sprinkler irrigation streams reduced runoff 70% and sediment loss 75%, but tension infiltration
measurements were inconsistent, suggesting changes in surface-sealing effects with sprinkler
application of PAM are transient
Entanglement of two-mode Bose-Einstein condensates
We investigate the entaglement characteristics of two general bimodal
Bose-Einstein condensates - a pair of tunnel-coupled Bose-Einstein condensates
and the atom-molecule Bose-Einstein condensate. We argue that the entanglement
is only physically meaningful if the system is viewed as a bipartite system,
where the subsystems are the two modes. The indistinguishibility of the
particles in the condensate means that the atomic constituents are physically
inaccessible and thus the degree of entanglement between individual particles,
unlike the entanglement between the modes, is not experimentally relevant so
long as the particles remain in the condensed state. We calculate the
entanglement between the modes for the exact ground state of the two bimodal
condensates and consider the dynamics of the entanglement in the tunnel-coupled
case.Comment: 11 pages, 8 figures, submitted to Physical Review A, to be presented
at the third UQ Mathematical Physics workshop, Oct. 4-6; changes made in
response to referee comment
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