2,111 research outputs found
Quark-gluon vertex with an off-shell O(a)-improved chiral fermion action
We perform a study the quark-gluon vertex function with a quenched Wilson
gauge action and a variety of fermion actions. These include the domain wall
fermion action (with exponentially accurate chiral symmetry) and the Wilson
clover action both with the non-perturbatively improved clover coefficient as
well as with a number of different values for this coefficient. We find that
the domain wall vertex function behaves very well in the large momentum
transfer region. The off-shell vertex function for the on-shell improved clover
class of actions does not behave as well as the domain wall case and,
surprisingly, shows only a weak dependence on the clover coefficient
for all components of its Dirac decomposition and across all momenta. Including
off-shell improvement rotations for the clover fields can make this action
yield results consistent with those from the domain wall approach, as well as
helping to determine the off-shell improved coefficient .Comment: 11 pages, 13 figures, REVTeX
Exploration of the Neuronal Subtype Specificity of an Ethanol Responsive Gene: Glycogen Synthase Kinase 3 Beta (Gsk3b)
Exploration of the Neuronal Subtype Specificity of an Ethanol Responsive Gene: Glycogen Synthase Kinase 3 Beta (Gsk3b)
Dalton Huey, Depts. of Bioinformatics, Biology & Chemistry, A. van der Vaart, G. M. Harris, and M. F. Miles, with Dr. Sarah Golding, Dept. of Biology
Previous work done in our laboratory revealed that Glycogen Synthase Kinase 3 Beta (Gsk3b) functions as a hub gene in a network of genes regulated by acute ethanol in the medial prefrontal cortex (mPFC) across a mouse genetic panel. Adult mice treated with acute ethanol showed increased phosphorylation of GSK3B on the Ser9 residue in prefrontal cortex. Subsequent viral-mediated overexpression of Gsk3bin mouse mPFC caused an increase in ethanol consumption and pharmacological inhibition of GSK3B decreased ethanol consumption. However, it is unknown what neuron subtypes are driving this change in behavior. Here, we provide evidence that deletion of Gsk3bin Camk2a+ glutamatergic neurons of the mPFC results in a decrease in ethanol consumption in both continuous and intermittent access drinking paradigms. Furthermore, we have recently designed and validated a plasmid for Cre-dependent overexpression of Gsk3b, along with a Cre-dependent reporter as a control. These plasmids are planned for use in conjunction with different Cre drivers for viral-mediated expression in any cell type. Dissection of the neural circuitry of this ethanol responsive pathway can lead to a better assessment of Gsk3bas a potential target for the treatment of alcohol use disorders. Work supported by grants R01A027581 and P50AA022537 to MFM.https://scholarscompass.vcu.edu/uresposters/1313/thumbnail.jp
The preservation of atmospheric nitrate in snow at Summit, Greenland
There is great interest in using nitrate NO3 isotopic composition in ice cores to track the history of precursor nitrogen oxides (NOx = NO + NO2) in the atmosphere. Nitrate NO3 however can be lost from the snow by surface processes, such as photolysis back to NOx upon exposure to sunlight, making it difficult to interpret records of NO3 as a tracer of atmospheric NOx loading. In a campaign consisting of two field seasons (May–June) at Summit, Greenland, high temporal frequency surface snow samples were collected and analyzed for the oxygen isotopic composition of NO3. The strong, linear relationship observed between the oxygen isotopes of NO3 in both 2010 and 2011, is difficult to explain in the presence of significant post depositional processing of NO3 unless several unrelated variables change in concert. Therefore, the isotopic signature of NO3 in the snow at Summit is most feasibly explained as preserved atmospheric NO3 deposition
First Lattice Study of the - Transition Form Factors
Experiments at Jefferson Laboratory, MIT-Bates, LEGS, Mainz, Bonn, GRAAL, and
Spring-8 offer new opportunities to understand in detail how nucleon resonance
() properties emerge from the nonperturbative aspects of QCD. Preliminary
data from CLAS collaboration, which cover a large range of photon virtuality
show interesting behavior with respect to dependence: in the region
, both the transverse amplitude, , and the
longitudinal amplitude, , decrease rapidly. In this work, we
attempt to use first-principles lattice QCD (for the first time) to provide a
model-independent study of the Roper-nucleon transition form factor.Comment: 4 pages, 2 figures, double colum
Gravitational lensing statistical properties in general FRW cosmologies with dark energy component(s): analytic results
Various astronomical observations have been consistently making a strong case
for the existence of a component of dark energy with negative pressure in the
universe. It is now necessary to take the dark energy component(s) into account
in gravitational lensing statistics and other cosmological tests. By using the
comoving distance we derive analytic but simple expressions for the optical
depth of multiple image, the expected value of image separation and the
probability distribution of image separation caused by an assemble of singular
isothermal spheres in general FRW cosmological models with dark energy
component(s). We also present the kinematical and dynamical properties of these
kinds of cosmological models and calculate the age of the universe and the
distance measures, which are often used in classical cosmological tests. In
some cases we are able to give formulae that are simpler than those found
elsewhere in the literature, which could make the cosmological tests for dark
energy component(s) more convenient.Comment: 14 pages, no figure, Latex fil
Gravitational Lensing Statistics as a Probe of Dark Energy
By using the comoving distance, we derive an analytic expression for the
optical depth of gravitational lensing, which depends on the redshift to the
source and the cosmological model characterized by the cosmic mass density
parameter , the dark energy density parameter and its
equation of state . It is shown that, the larger the
dark energy density is and the more negative its pressure is, the higher the
gravitational lensing probability is. This fact can provide an independent
constraint for dark energy.Comment: 9 pages, 2 figure
First Calculation of Hyperon Axial Couplings from Lattice QCD
In this work, we report the first lattice calculation of hyperon axial
couplings, using the 2+1-flavor MILC configurations and domain-wall fermion
valence quarks. Both the and axial couplings are computed for
the first time in lattice QCD. In particular we find that and .Comment: 5 pages, 2 figure
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