1,374 research outputs found
New QCD Sum Rules for Nucleons in Nuclear Matter
Two new QCD sum rules for nucleons in nuclear matter are obtained from a
mixed correlator of spin-1/2 and spin-3/2 interpolating fields. These new sum
rules, which are insensitive to the poorly known four-quark condensates,
provide additional information on the nucleon scalar self-energy. These new sum
rules are analyzed along with previous spin-1/2 interpolator-based sum rules
which are also insensitive to the poorly known four-quark condensates. The
analysis indicates consistency with the expectations of relativistic nuclear
phenomenology at nuclear matter saturation density. However, a weaker density
dependence near saturation is suggested. Using previous estimates of in-medium
condensate uncertainties, we find GeV and
GeV at nuclear matter saturation density.Comment: 10 page RevTeX Manuscript with embedded figures. Revised manuscript
accepted for publication. This and related papers may also be obtained from
http://www.phys.washington.edu/~derek/Publications.htm
Numerical approximation of the Euler-Poisson-Boltzmann model in the quasineutral limit
This paper analyzes various schemes for the Euler-Poisson-Boltzmann (EPB)
model of plasma physics. This model consists of the pressureless gas dynamics
equations coupled with the Poisson equation and where the Boltzmann relation
relates the potential to the electron density. If the quasi-neutral assumption
is made, the Poisson equation is replaced by the constraint of zero local
charge and the model reduces to the Isothermal Compressible Euler (ICE) model.
We compare a numerical strategy based on the EPB model to a strategy using a
reformulation (called REPB formulation). The REPB scheme captures the
quasi-neutral limit more accurately
Application of dietary supplements in the prevention of type 2 diabetes-related cardiovascular complications
Joint review by the Leicester Institute for Pharmaceutical Innovation and the Institute for Allied Health Sciences Research, based on invited plenary lecture presented by Prof. Randolph Arroo at the conference 'Natural Products in Drug Discovery and Human Health' in Lisbon, 28-31 July, 2019
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Type 2 diabetes, which accounts for the vast majority of diabetes worldwide is the result of a lowered sensitivity of the insulin receptors, resulting in impaired sugar metabolism is and chronic hyperglycaemia. There is no cure for type 2 diabetes, though some people with pre-diabetes and diabetes manage to reach and hold normal blood sugar levels, thus avoiding most of the complications that come with chronic hyperglycaemia; this is sometimes referred to as ‘reversing diabetes’. A healthy diet, with sufficient amounts of fruits, nuts, and vegetables is positively correlated with maintaining glycaemic control and prevention of diabetes-related complications.
Whereas many different dietary phytochemicals have been considered to play a role in the glycaemic control and in prevention of degenerative diseases, there is currently no consensus on a particular mode of action. In this review, a range of pre-clinical studies and intervention studies, including randomised double-blind, placebo controlled clinical studies, are considered that investigate the role of dietary compounds in the prevention of type 2 diabetes-related complications. Three generic mechanisms of action can be discerned: compounds that reduce sugar uptake, compounds that restore insulin function, and compounds that attenuate the effects of oxidative stress and chronic inflammation. Particularly the latter has received wide attention in the form of activation of the Nrf2-antioxidant response element signalling pathway by various polyphenolic or triterpenoid compounds. Although individual reports may present models with clear looking signalling cascades, an overall review shows that many biologically active compounds in the human diet are pan assay interference substances that alter several cell functions simultaneously, which makes them less attractive for drug development
Analysis of the genome sequence of an alpaca coronavirus
AbstractCoronaviral infection of New World camelids was first identified in 1998 in llamas and alpacas with severe diarrhea. In order to understand this infection, one of the coronavirus isolates was sequenced and analyzed. It has a genome of 31,076 nt including the poly A tail at the 3′ end. This virus designated as ACoV-00-1381 (ACoV) encodes all 10 open reading frames (ORFs) characteristic of Group 2 bovine coronavirus (BCoV). Phylogenetic analysis showed that the ACoV genome is clustered closely (>99.5% identity) with two BCoV strains, ENT and LUN, and was also closely related to other BCoV strains (Mebus, Quebec, DB2), a human corona virus (strain 043) (>96%), and porcine hemagglutinating encephalomyelitis virus (>93% identity). A total of 145 point mutations and one nucleotide deletion were found relative to the BCoV ENT. Most of the ORFs were highly conserved; however, the predicted spike protein (S) has 9 and 12 amino acid differences from BCoV LUN and ENT, respectively, and shows a higher relative number of changes than the other proteins. Phylogenetic analysis suggests that ACoV shares the same ancestor as BCoV ENT and LUN
Adiabatic Output Coupling of a Bose Gas at Finite Temperatures
We develop a general theory of adiabatic output coupling from trapped atomic
Bose-Einstein Condensates at finite temperatures. For weak coupling, the output
rate from the condensate, and the excited levels in the trap, settles in a time
proportional to the inverse of the spectral width of the coupling to the output
modes. We discuss the properties of the output atoms in the quasi-steady-state
where the population in the trap is not appreciably depleted. We show how the
composition of the output beam, containing condensate and thermal component,
may be controlled by changing the frequency of the output coupler. This
composition determines the first and second order coherence of the output beam.
We discuss the changes in the composition of the bose gas left in the trap and
show how nonresonant output coupling can stimulate either the evaporation of
thermal excitations in the trap or the growth of non-thermal excitations, when
pairs of correlated atoms leave the condensate.Comment: 22 pages, 6 Figs. To appear in Physical Review A All the typos from
the previous submission have been fixe
Hydrogen-bonded Silica Gels Dispersed in a Smectic Liquid Crystal: A Random Field XY System
The effect on the nematic to smectic-A transition in octylcyanobiphenyl (8CB)
due to dispersions of hydrogen-bonded silica (aerosil) particles is
characterized with high-resolution x-ray scattering. The particles form weak
gels in 8CB creating a quenched disorder that replaces the transition with the
growth of short range smectic correlations. The correlations include thermal
critical fluctuations that dominate at high temperatures and a second
contribution that quantitatively matches the static fluctuations of a random
field system and becomes important at low temperatures.Comment: 10 pages, 4 postscript figures as separate file
In-medium pion weak decay constants
In nuclear matter, the pion weak decay constant is separated into the two
components corresponding to the time and space components of the
axial-vector current. Using QCD sum rules, we compute the two decay constants
from the pseudoscalar-axial vector correlation function in the matter . It is found that the sum rule for
satisfies the in-medium Gell-Mann--Oakes--Renner (GOR) relation precisely while
the sum rule does not. The sum rule contains the non-negligible
contribution from the dimension 5 condensate in addition to the
in-medium quark condensate. Using standard set of QCD parameters and ignoring
the in-medium change of the pion mass, we obtain MeV at the nuclear
saturation density. The prediction for depends on values of the dimension
5 condensate and on the Borel mass. However, the OPE constrains that , which does not agree with the prediction from the in-medium chiral
perturbation theory. Depending on the value of the dimension 5 condensate,
at the saturation density is found to be in the range MeV
at the Borel mass GeV.Comment: 19 pages including two postscript figures, substantially revise
Nature of Correlated Motion of Electrons in the Parent Cobaltate Superconductors
Recently discovered class of cobaltate superconductors (Na0.3CoO2.nH2O) is a
novel realization of interacting quantum electron systems in a triangular
network with low-energy degrees of freedom. We employ angle-resolved
photoemission spectroscopy to uncover the nature of microscopic electron motion
in the parent superconductors for the first time. Results reveal a large
hole-like Fermi surface (consistent with Luttinger theorem) generated by the
crossing of super-heavy quasiparticles. The measured quasiparticle parameters
collectively suggest a two orders of magnitude departure from the conventional
Bardeen-Cooper-Schrieffer electron dynamics paradigm and unveils cobaltates as
a rather hidden class of relatively high temperature superconductors.Comment: 5 pages, 4 figures, 1 tabl
Ideal Gases in Time-Dependent Traps
We investigate theoretically the properties of an ideal trapped gas in a
time-dependent harmonic potential. Using a scaling formalism, we are able to
present simple analytical results for two important classes of experiments:
free expansion of the gas upon release of the trap; and the response of the gas
to a harmonic modulation of the trapping potential is investigated. We present
specific results relevant to current experiments on trapped Fermions.Comment: 5 pages, 3 eps figure
Scattering of a longitudinal wave by a circular crack in a fluid-saturated porous medium
Physical properties of many natural and man-made materials can be modelled using the concept of poroelasticity. Some porous materials, in addition to the network of pores, contain larger inhomogeneities such as inclusions, cavities, fractures or cracks. A common method of detecting such inhomogeneities is based on the use of elastic wave scattering. We consider interaction of a normally incident time-harmonic longitudinal plane wave with a circular crack imbedded in a porous medium governed by Biot's equations of dynamic poroelasticity. The problem is formulated in cylindrical co-ordinates as a system of dual integral equations for the Hankel transform of the wave field, which is then reduced to a single Fredholm integral equation of the second kind. It is found that the scattering that takes place is predominantly due to wave inducedfluid flow between the pores and the crack. The scattering magnitude depends on the size of the crack relative to the slow wave wavelength and has it's maximum value when they are of the same order
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