413 research outputs found
Heavy Supersymmetric Particle Effects in Higgs Boson Production Associated with a Bottom Quark Pair at LHC and Tevatron
If all the supersymmetry particles (sparticles) except a light Higgs boson
are too heavy to be directly produced at the Large Hadron Collider (LHC) and
Tevatron, a possible way to reveal evidence for supersymmetry is through their
virtual effects in other processes. We examine such supersymmetric QCD effects
in bottom pair production associated with a light Higgs boson at the LHC and
Tevatron. We find that if the relevant sparticles (gluinos and squarks) are
well above the TeV scale, too heavy to be directly produced, they can still
have sizable virtual effects in this process. For large , such
residual effects can alter the production rate by as much as 40 percent, which
should be observable in future measurements of this process.Comment: results for Tevatron added, version in PR
Transforming a Corner of a Light-Frame Wood Structure to a Set of Nonlinear Springs
The computational efficiency of a full-structure model for a light-frame building is enhanced by replacing the continuum of the detailed connections with rotational and translational nonlinear springs that are energetically equivalent between two bounds. This study examines the transformation from the physical exterior-wall-to-exterior-wall connection (a corner) of a light-frame wood structure, first, to a two-dimensional finite-element model and, then, to a set of nonlinear springs. Typical light-frame details are used as the starting point, and the product is the characteristic moment-rotation and load-displacement relationships for a 24-inch segment of the corner
The Rise Times of High and Low Redshift Type Ia Supernovae are Consistent
We present a self-consistent comparison of the rise times for low- and
high-redshift Type Ia supernovae. Following previous studies, the early light
curve is modeled using a t-squared law, which is then mated with a modified
Leibundgut template light curve. The best-fit t-squared law is determined for
ensemble samples of low- and high-redshift supernovae by fitting simultaneously
for all light curve parameters for all supernovae in each sample. Our method
fully accounts for the non-negligible covariance amongst the light curve
fitting parameters, which previous analyses have neglected. Contrary to Riess
et al. (1999), we find fair to good agreement between the rise times of the
low- and high-redshift Type Ia supernovae. The uncertainty in the rise time of
the high-redshift Type Ia supernovae is presently quite large (roughly +/- 1.2
days statistical), making any search for evidence of evolution based on a
comparison of rise times premature. Furthermore, systematic effects on rise
time determinations from the high-redshift observations, due to the form of the
late-time light curve and the manner in which the light curves of these
supernovae were sampled, can bias the high-redshift rise time determinations by
up to +3.6/-1.9 days under extreme situations. The peak brightnesses - used for
cosmology - do not suffer any significant bias, nor any significant increase in
uncertainty.Comment: 18 pages, 4 figures, Accepted for publication in the Astronomical
Journal. Also available at http://www.lbl.gov/~nugent/papers.html Typos were
corrected and a few sentences were added for improved clarit
Vena cava inferior thrombosis detected by venous hum: a case report
We describe a patient in which a venous hum, heard during abdominal auscultation, lead to the diagnosis of a vena cava inferior thrombosis
Tests of the Accelerating Universe with Near-Infrared Observations of a High-Redshift Type Ia Supernova
We have measured the rest-frame B,V, and I-band light curves of a
high-redshift type Ia supernova (SN Ia), SN 1999Q (z=0.46), using HST and
ground-based near-infrared detectors.
A goal of this study is the measurement of the color excess, E_{B-I}, which
is a sensitive indicator of interstellar or intergalactic dust which could
affect recent cosmological measurements from high-redshift SNe Ia. Our
observations disfavor a 30% opacity of SN Ia visual light by dust as an
alternative to an accelerating Universe. This statement applies to both
Galactic-type dust
(rejected at the 3.4 sigma confidence level) and greyer dust (grain size >
0.1 microns; rejected at the 2.3 to 2.6 sigma confidence level) as proposed by
Aguirre (1999). The rest-frame -band light cur ve shows the secondary
maximum a month after B maximum typical of nearby SNe Ia of normal luminosi ty,
providing no indication of evolution as a function of redshift out to z~0.5. A
n expanded set of similar observations could improve the constraints on any
contribution of extragalactic dust to the dimming of high-redshift SNe Ia.Comment: Accepted to the Astrophysical Journal, 12 pages, 2 figure
Lattice results for the decay constant of heavy-light vector mesons
We compute the leptonic decay constants of heavy-light vector mesons in the
quenched approximation. The reliability of lattice computations for heavy
quarks is checked by comparing the ratio of vector to pseudoscalar decay
constant with the prediction of Heavy Quark Effective Theory in the limit of
infinitely heavy quark mass. Good agreement is found. We then calculate the
decay constant ratio for B mesons: .
We also quote quenched MeV.Comment: 11 pages, 3 postscript figs., revtex; two references adde
Murine Fig4 is dispensable for muscle development but required for muscle function
Abstract
Background
Phosphatidylinositol phosphates (PIPs) are low-abundance phospholipids that participate in a range of cellular processes, including cell migration and membrane traffic. PIP levels and subcellular distribution are regulated by a series of lipid kinases and phosphatases. In skeletal muscle, PIPs and their enzymatic regulators serve critically important functions exemplified by mutations of the PIP phosphatase MTM1 in myotubular myopathy (MTM), a severe muscle disease characterized by impaired muscle structure and abnormal excitationâcontraction coupling. FIG4 functions as a PIP phosphatase that participates in both the synthesis and breakdown of phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2). Mutation of FIG4 results in a severe neurodegenerative disorder in mice and a progressive peripheral polyneuropathy in humans. The effect of FIG4 mutation on skeletal muscle has yet to be examined.
Methods
Herein we characterize the impact of FIG4 on skeletal muscle development and function using the spontaneously occurring mouse mutant pale tremor (plt), a mouse line with a loss of function mutation in Fig4.
Results
In plt mice, we characterized abnormalities in skeletal muscle, including reduced muscle size and specific force generation. We also uncovered ultrastructural abnormalities and increased programmed cell death. Conversely, we detected no structural or functional abnormalities to suggest impairment of excitationâcontraction coupling, a process previously shown to be influenced by PI(3,5)P2 levels. Conditional rescue of Fig4 mutation in neurons prevented overt muscle weakness and the development of obvious muscle abnormalities, suggesting that the changes observed in the plt mice were primarily related to denervation of skeletal muscle. On the basis of the ability of reduced FIG4 levels to rescue aspects of Mtmr2-dependent neuropathy, we evaluated the effect of Fig4 haploinsufficiency on the myopathy of Mtm1-knockout mice. Male mice with a compound Fig4
+/â/Mtm1
â/Y genotype displayed no improvements in muscle histology, muscle size or overall survival, indicating that FIG4 reduction does not ameliorate the Mtm1-knockout phenotype.
Conclusions
Overall, these data indicate that loss of Fig4 impairs skeletal muscle function but does not significantly affect its structural development.http://deepblue.lib.umich.edu/bitstream/2027.42/112676/1/13395_2013_Article_83.pd
Landscape Analysis for the Specimen Data Refinery
This report reviews the current state-of-the-art applied approaches on automated tools, services and workflows for extracting information from images of natural history specimens and their labels. We consider the potential for repurposing existing tools, including workflow management systems; and areas where more development is required. This paper was written as part of the SYNTHESYS+ project for software development teams and informatics teams working on new software-based approaches to improve mass digitisation of natural history specimens
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