1,749 research outputs found
Thermodynamic Limit for the Invariant Measures in Supercritical Zero Range Processes
We prove a strong form of the equivalence of ensembles for the invariant
measures of zero range processes conditioned to a supercritical density of
particles. It is known that in this case there is a single site that
accomodates a macroscopically large number of the particles in the system. We
show that in the thermodynamic limit the rest of the sites have joint
distribution equal to the grand canonical measure at the critical density. This
improves the result of Gro\ss kinsky, Sch\"{u}tz and Spohn, where convergence
is obtained for the finite dimensional marginals. We obtain as corollaries
limit theorems for the order statistics of the components and for the
fluctuations of the bulk
Expression of cholesterol packaging and transport genes in human and rat placenta: impact of obesity and a high-fat diet
Evidence suggests that sub-optimal maternal nutrition has implications for the developing offspring. We have previously shown that exposure to a low-protein diet during gestation was associated with upregulation of genes associated with cholesterol transport and packaging within the placenta. This study aimed to elucidate the effect of altering maternal dietary linoleic acid (LA; omega-6) to alpha-linolenic acid (ALA; omega-6) ratios as well as total fat content on placental expression of genes associated with cholesterol transport. The potential for maternal body mass index (BMI) to be associated with expression of these genes in human placental samples was also evaluated. Placentas were collected from 24 Wistar rats at 20-day gestation (term = 21–22-day gestation) that had been fed one of four diets containing varying fatty acid compositions during pregnancy, and from 62 women at the time of delivery. Expression of 14 placental genes associated with cholesterol packaging and transfer was assessed in rodent and human samples by quantitative real time polymerase chain reaction. In rats, placental mRNA expression of ApoA2, ApoC2, Cubn, Fgg, Mttp and Ttr was significantly elevated (3–30 fold) in animals fed a high LA (36% fat) diet, suggesting increased cholesterol transport across the placenta in this group. In women, maternal BMI was associated with fewer inconsistent alterations in gene expression. In summary, sub-optimal maternal nutrition is associated with alterations in the expression of genes associated with cholesterol transport in a rat model. This may contribute to altered fetal development and potentially programme disease risk in later life. Further investigation of human placenta in response to specific dietary interventions is required
A compartive study of the retentive capability of the Sydney mini-screw with 6mm orthodontic anchorage miniscrews in the tibia and femur of New Zealand rabbits by removal torque test
Aim: To investigate the retentive capability of the Sydney Mini-screw with injectable bone cement by removal torque. Method: 16 New Zealand White rabbits were divided evenly into 2 groups, T1 0 week to assess primary stability and T2 8 weeks to test secondary stability. Three groups of miniscrews Sydney Mini-screw with Cement (SMSC) N=12, Sydney Miniscrew without cement (SMS) N=10 and control Aarhus (CA) 6mm screw N=10 were placed randomly and evenly between the right and left tibial and femoral sites. The SMSC and SMS required predrilling of a pilot hole and the SMSC had injectable bone cement PRODENSE. Removal torque was measured and Friedman's Test and two-sample t-test were used for statistical analysis, where appropriate. Results: Removal torque values at T1 for CA, SMS, SMSC were not significantly different (p=0.072) but were significantly different at T2 (p=0.012). Only SMS (p=0.006) showed statistically significant difference between T1 and T2. The different surgical locations at T2 did not statistically differ from each other either (p=0.948). Conclusion: Sydney Miniscrew with and without cement had significantly higher secondary stability and had a trend towards increased primary compared to a normal control miniscrew. More research is required with an increased sample size
The effect of maternal dietary fat content and omega-6 to omega-3 ratio on offspring growth and hepatic gene expression in the rat
© The Authors 2020. Omega-6 fatty acids have been shown to exert pro-adipogenic effects whereas omega-3 fatty acids work in opposition. Increasing intakes of LA (linoleic acid; omega-6) vs ALA (alpha-linolenic acid; omega-3) in Western diets has led to the hypothesis that consumption of this diet during pregnancy may be contributing to adverse offspring health. This study investigated the effects of feeding a maternal dietary LA:ALA ratio similar to that of the Western diet (9:1) compared to a proposed 'ideal' ratio (∼1:1.5), at two total fat levels (18% vs 36% fat w/w), on growth and lipogenic gene expression in the offspring. Female Wistar rats were assigned to one of the four experimental groups throughout gestation and lactation. Offspring were culled at 1 and 2 weeks of age for sample collection. Offspring of dams consuming a -36% fat diet were ∼20% lighter than those exposed to a 18% fat diet (
Exposure to maternal obesity during suckling outweighs in utero exposure in programming for post-weaning adiposity and insulin resistance in rats
Exposure to maternal obesity during early development programmes adverse metabolic health in rodent offspring. We assessed the relative contributions of obesity during pregnancy and suckling on metabolic health post-weaning. Wistar rat offspring exposed to control (C) or cafeteria diet (O) during pregnancy were cross-fostered to dams on the same (CC, OO) or alternate diet during suckling (CO, OC) and weaned onto standard chow. Measures of offspring metabolic health included growth, adipose tissue mass, and 12-week glucose and insulin concentrations during an intraperitoneal glucose tolerance test (ipGTT). Exposure to maternal obesity during lactation was a driver for reduced offspring weight post-weaning, higher fasting blood glucose concentrations and greater gonadal adiposity (in females). Males displayed insulin resistance, through slower glucose clearance despite normal circulating insulin and lower mRNA expression of PIK3R1 and PIK3CB in gonadal fat and liver respectively. In contrast, maternal obesity during pregnancy up-regulated the insulin signalling genes IRS2, PIK3CB and SREBP1-c in skeletal muscle and perirenal fat, favouring insulin sensitivity. In conclusion exposure to maternal obesity during lactation programmes offspring adiposity and insulin resistance, overriding exposure to an optimal nutritional environment in utero, which cannot be alleviated by a nutritionally balanced post-weaning diet
Boundary driven zero-range processes in random media
The stationary states of boundary driven zero-range processes in random media
with quenched disorder are examined, and the motion of a tagged particle is
analyzed. For symmetric transition rates, also known as the random barrier
model, the stationary state is found to be trivial in absence of boundary
drive. Out of equilibrium, two further cases are distinguished according to the
tail of the disorder distribution. For strong disorder, the fugacity profiles
are found to be governed by the paths of normalized -stable
subordinators. The expectations of integrated functions of the tagged particle
position are calculated for three types of routes.Comment: 23 page
Early stage morphology of quench condensed Ag, Pb and Pb/Ag hybrid films
Scanning Tunneling Microscopy (STM) has been used to study the morphology of
Ag, Pb and Pb/Ag bilayer films fabricated by quench condensation of the
elements onto cold (T=77K), inert and atomically flat Highly Oriented Pyrolytic
Graphite (HOPG) substrates. All films are thinner than 10 nm and show a
granular structure that is consistent with earlier studies of QC films. The
average lateral diameter, , of the Ag grains, however, depends on
whether the Ag is deposited directly on HOPG ( = 13 nm) or on a Pb
film consisting of a single layer of Pb grains ( = 26.8 nm). In
addition, the critical thickness for electrical conduction () of Pb/Ag
films on inert glass substrates is substantially larger than for pure Ag films.
These results are evidence that the structure of the underlying substrate
exerts an influence on the size of the grains in QC films. We propose a
qualitative explanation for this previously unencountered phenomenon.Comment: 11 pages, 3 figures and one tabl
A study of the centrally produced baryon-antibaryon systems in pp interactions at 450 GeV/c
A study of the centrally produced ppbar, ppbarpi, ppbarpipi and lambda lambda
channels has been performed in pp collisions using an incident beam momentum of
450 GeV/c. No significant new structures are observed in the mass spectra,
however, important new information on the production dynamics is obtained. A
systematic study of the production properties of these systems has been
performed and it is found that these systems are not produced dominantly by
double Pomeron exchange.Comment: 13 pages, Latex, 4 Figure
Density-functional theory of quantum wires and dots in a strong magnetic field
We study the competition between the exchange and the direct Coulomb
interaction near the edge of a two-dimensional electron gas in a strong
magnetic field using density-functional theory in a local approximation for the
exchange-energy functional. Exchange is shown to play a significant role in
reducing the spatial extent of the compressible edge channel regions obtained
from an electrostatic description. The transition from the incompressible edge
channels of the Hartree-Fock picture to the broad, compressible strips
predicted by electrostatics occurs within a narrow and experimentally
accessible range of confinement strengths.Comment: 24 pages latex and 10 postscript figures in self extracting fil
A study of pseudoscalar states produced centrally in pp interactions at 450 GeV/c
A study has been made of pseudoscalar mesons produced centrally in pp
interactions. The results show that the eta and etaprime appear to have a
similar production mechanism which differs from that of the pi0. The production
properties of the eta and etaprime are not consistent with what is expected
from double Pomeron exchange. In addition the production mechanism for the eta
and etaprime is such that the production cross section are greatest when the
azimuthal angle between the pT vectors of the two protons is 90 degrees.Comment: 11 pages, Latex, 3 Figure
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