752 research outputs found
Associations between the K232A polymorphism in the diacylglycerol-O-transferase 1 (DGAT1) gene and performance in Irish Holstein-Friesian dairy cattle
peer-reviewedSelection based on genetic polymorphisms requires accurate quantification of the
effect or association of the polymorphisms with all traits of economic importance.
The objective of this study was to estimate, using progeny performance data on 848
Holstein-Friesian bulls, the association between a non-conservative alanine to lysine
amino acid change (K232A) in exon 8 of the diacylglycerol-O-transferase 1 (DGAT1)
gene and milk production and functionality in the Irish Holstein-Friesian population.
The DGAT1 gene encodes the diacylglycerol-O-transferase microsomal enzyme
necessary to catalyze the final step in triglyceride synthesis. Weighted mixed model
methodology, accounting for the additive genetic relationships among animals, was
used to evaluate the association between performance and the K232A polymorphism.
The minor allele frequency (K allele) was 0.32. One copy of the K allele was associated
(P < 0.001) with 77 kg less milk yield, 4.22 kg more fat yield, 0.99 kg less protein
yield, and 1.30 and 0.28 g/kg greater milk fat and protein concentration, respectively;
all traits were based on predicted 305-day production across the first five lactations.
The K232A polymorphism explained 4.8%, 10.3% and 1.0% of the genetic variance in
milk yield, fat yield and protein yield, respectively. There was no association between
the K232A polymorphism and fertility, functional survival, calving performance,
carcass traits, or any conformation trait with the exception of rump width and carcass
conformation. Using the current economic values for the milk production traits
in the Irish total merit index, one copy of the K allele is worth €5.43 in expected
profitability of progeny. Results from this study will be useful in quantifying the
cost-benefit of including the K232A polymorphism in the Irish national breeding programme
Probing the MSSM Higgs Sector at an e-e- Collider
The theoretical structure of the Higgs sector of the Minimal Supersymmetric
Standard Model (MSSM) is briefly described. An outline of Higgs phenomenology
at future lepton colliders is presented, and some opportunities for probing the
physics of the MSSM Higgs sector at an e-e- collider are considered.Comment: 14 pages, needs e-e-ijmpa.sty and psfig.sty, to appear in the
Proceedings of e-e- 97, International Journal of Modern Physics A, Special
Proceedings Issue, June 199
Fluctuations of an evaporating black hole from back reaction of its Hawking radiation: Questioning a premise in earlier work
This paper delineates the first steps in a systematic quantitative study of
the spacetime fluctuations induced by quantum fields in an evaporating black
hole. We explain how the stochastic gravity formalism can be a useful tool for
that purpose within a low-energy effective field theory approach to quantum
gravity. As an explicit example we apply it to the study of the
spherically-symmetric sector of metric perturbations around an evaporating
black hole background geometry. For macroscopic black holes we find that those
fluctuations grow and eventually become important when considering sufficiently
long periods of time (of the order of the evaporation time), but well before
the Planckian regime is reached. In addition, the assumption of a simple
correlation between the fluctuations of the energy flux crossing the horizon
and far from it, which was made in earlier work on spherically-symmetric
induced fluctuations, is carefully analyzed and found to be invalid. Our
analysis suggests the existence of an infinite amplitude for the fluctuations
of the horizon as a three-dimensional hypersurface. We emphasize the need for
understanding and designing operational ways of probing quantum metric
fluctuations near the horizon and extracting physically meaningful information.Comment: 10 pages, REVTeX; minor changes, a few references added and a brief
discussion of their relevance included. To appear in the proceedings of the
10th Peyresq meeting. Dedicated to Rafael Sorkin on the occasion of his 60th
birthda
The Paradox of Muscle Hypertrophy in Muscular Dystrophy
Mutations in the dystrophin gene cause Duchenne and Becker muscular dystrophy in humans and syndromes in mice, dogs, and cats. Affected humans and dogs have progressive disease that leads primarily to muscle atrophy. Mdx mice progress through an initial phase of muscle hypertrophy followed by atrophy. Cats have persistent muscle hypertrophy. Hypertrophy in humans has been attributed to deposition of fat and connective tissue (pseudohypertrophy). Increased muscle mass (true hypertrophy) has been documented in animal models. Muscle hypertrophy can exaggerate postural instability and joint contractures. Deleterious consequences of muscle hypertrophy should be considered when developing treatments for muscular dystrophy
High-precision B(E2) measurements of semi-magic Ni 58,60,62,64 by Coulomb excitation
High-precision reduced electric-quadrupole transition probabilities B(E2;01+→21+) have been measured from single-step Coulomb excitation of semi-magic Ni58,60,62,64 (Z=28) beams at 1.8 MeV per nucleon on a natural carbon target. The energy loss of the
Generalizations of entanglement based on coherent states and convex sets
Unentangled pure states on a bipartite system are exactly the coherent states
with respect to the group of local transformations. What aspects of the study
of entanglement are applicable to generalized coherent states? Conversely, what
can be learned about entanglement from the well-studied theory of coherent
states? With these questions in mind, we characterize unentangled pure states
as extremal states when considered as linear functionals on the local Lie
algebra. As a result, a relativized notion of purity emerges, showing that
there is a close relationship between purity, coherence and (non-)entanglement.
To a large extent, these concepts can be defined and studied in the even more
general setting of convex cones of states. Based on the idea that entanglement
is relative, we suggest considering these notions in the context of partially
ordered families of Lie algebras or convex cones, such as those that arise
naturally for multipartite systems. The study of entanglement includes notions
of local operations and, for information-theoretic purposes, entanglement
measures and ways of scaling systems to enable asymptotic developments. We
propose ways in which these may be generalized to the Lie-algebraic setting,
and to a lesser extent to the convex-cones setting. One of our original
motivations for this program is to understand the role of entanglement-like
concepts in condensed matter. We discuss how our work provides tools for
analyzing the correlations involved in quantum phase transitions and other
aspects of condensed-matter systems.Comment: 37 page
Model Independent Approach to Focus Point Supersymmetry: from Dark Matter to Collider Searches
The focus point region of supersymmetric models is compelling in that it
simultaneously features low fine-tuning, provides a decoupling solution to the
SUSY flavor and CP problems, suppresses proton decay rates and can accommodate
the WMAP measured cold dark matter (DM) relic density through a mixed
bino-higgsino dark matter particle. We present the focus point region in terms
of a weak scale parameterization, which allows for a relatively model
independent compilation of phenomenological constraints and prospects. We
present direct and indirect neutralino dark matter detection rates for two
different halo density profiles, and show that prospects for direct DM
detection and indirect detection via neutrino telescopes such as IceCube and
anti-deuteron searches by GAPS are especially promising. We also present LHC
reach prospects via gluino and squark cascade decay searches, and also via
clean trilepton signatures arising from chargino-neutralino production. Both
methods provide a reach out to m_{\tg}\sim 1.7 TeV. At a TeV-scale linear
e^+e^- collider (LC), the maximal reach is attained in the \tz_1\tz_2 or
\tz_1\tz_3 channels. In the DM allowed region of parameter space, a
\sqrt{s}=0.5 TeV LC has a reach which is comparable to that of the LHC.
However, the reach of a 1 TeV LC extends out to m_{\tg}\sim 3.5 TeV.Comment: 34 pages plus 36 eps figure
Electromagnetic properties of the 21+ state in 134Te: Influence of core excitation on single-particle orbits beyond 132Sn
The g factor and B(E2) of the first excited 2+ state have been measured following Coulomb excitation of the neutron-rich semimagic nuclide 134Te (two protons outside 132Sn) produced as a radioactive beam. The precision achieved matches related g-factor m
Mixed Wino Dark Matter: Consequences for Direct, Indirect and Collider Detection
In supersymmetric models with gravity-mediated SUSY breaking and gaugino mass
unification, the predicted relic abundance of neutralinos usually exceeds the
strict limits imposed by the WMAP collaboration. One way to obtain the correct
relic abundance is to abandon gaugino mass universality and allow a mixed
wino-bino lightest SUSY particle (LSP). The enhanced annihilation and
scattering cross sections of mixed wino dark matter (MWDM) compared to bino
dark matter lead to enhanced rates for direct dark matter detection, as well as
for indirect detection at neutrino telescopes and for detection of dark matter
annihilation products in the galactic halo. For collider experiments, MWDM
leads to a reduced but significant mass gap between the lightest neutralinos so
that chi_2^0 two-body decay modes are usually closed. This means that dilepton
mass edges-- the starting point for cascade decay reconstruction at the CERN
LHC-- should be accessible over almost all of parameter space. Measurement of
the m_{\tz_2}-m_{\tz_1} mass gap at LHC plus various sparticle masses and cross
sections as a function of beam polarization at the International Linear
Collider (ILC) would pinpoint MWDM as the dominant component of dark matter in
the universe.Comment: 29 pages including 19 eps figure
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