43 research outputs found
Charges and fluxes in Maxwell theory on compact manifolds with boundary
We investigate the charges and fluxes that can occur in higher-order Abelian
gauge theories defined on compact space-time manifolds with boundary. The
boundary is necessary to supply a destination to the electric lines of force
emanating from brane sources, thus allowing non-zero net electric charges, but
it also introduces new types of electric and magnetic flux. The resulting
structure of currents, charges, and fluxes is studied and expressed in the
language of relative homology and de Rham cohomology and the corresponding
abelian groups. These can be organised in terms of a pair of exact sequences
related by the Poincar\'e-Lefschetz isomorphism and by a weaker flip symmetry
exchanging the ends of the sequences. It is shown how all this structure is
brought into play by the imposition of the appropriately generalised Maxwell's
equations. The requirement that these equations be integrable restricts the
world-volume of a permitted brane (assumed closed) to be homologous to a cycle
on the boundary of space-time. All electric charges and magnetic fluxes are
quantised and satisfy the Dirac quantisation condition. But through some
boundary cycles there may be unquantised electric fluxes associated with
quantised magnetic fluxes and so dyonic in nature.Comment: 28 pages, plain Te
Delayed developmental changes in neonatal vocalizations correlates with variations in ventral medial hypothalamus and central amygdala development in the rodent infant: Effects of prenatal cocaine
While variations in neonatal distress vocalizations have long been shown to reflect the integrity of nervous system development following a wide range of prenatal and perinatal insults, a paucity of research has explored the neurobiological basis of these variations. To address this, virgin Sprague-Dawley rats were bred and divided into three groups: (1) untreated, (2) chronic-cocaine treated (30mg/kg/day, gestation days (GDs) 1–20); or (3) chronic-saline treated (2mg/kg/day, GDs 1–20). Pregnant dams were injected with Bromodeoxyuridine (10mg/kg) on GDs 13–15 to label proliferating cells in limbic regions of interest. Ultrasonic vocalizations (USVs) were recorded on PNDs 1, 14, and 21, from one male and female pup per litter. Variations in acoustic properties of USVs following cocaine-exposure were age and sex-dependent including measures of total number, total duration and amplitude of USVs, and percent of USVs with at least one harmonic. Following USV testing brains were stained with standard fluorescent immunohistochemistry protocols and examined for variations in neuronal development and if variations were associated with acoustic characteristics. Limbic region developmental differences following cocaine-exposure were sex- and age-dependent with variations in the ventral medial hypothalamus and central amygdala correlating with variations in vocalizations on PND 14 and 21. Results suggest maturation of the ventral medial hypothalamus and central amygdala may provide the basis for variations in the sound and production of USVs. As vocalizations may serve as a neurobehavioral marker for nervous system integrity, understanding the neurobiological basis of neonatal vocalizations may provide the basis for early intervention strategies in high-risk infant populations
Growth and nutrient concentration of two native forage legumes inoculated with Rhizobium and Mycorrhiza in Missouri, USA
Neuropeptide-Y in the paraventricular nucleus increases ethanol self-administration
The paraventricular nucleus (PVN) of the hypothalamus is known to modulate feeding, obesity, and ethanol intake. Neuropeptide-Y (NPY), which is released endogenously by neurons projecting from the arcuate nucleus to the PVN, is one of the most potent stimulants of feeding behavior known. The role of NPY in the PVN on ethanol self-administration is unknown. To address this issue, rats were trained to self-administer ethanol via a sucrose fading procedure and injector guide cannulae aimed at the PVN were surgically implanted. Microinjections of NPY and NPY antagonists in the PVN were conducted prior to ethanol self-administration sessions. All doses of NPY significantly increased ethanol self-administration and preference, and decreased water intake. The NPY antagonist D-NPY partially reduced ethanol self-administration and completely blocked the effects of an intermediate dose of NPY (10 fmol) on ethanol intake, preference, and water intake. The competitive non-peptide Y1 receptor antagonist BIBP 3226 did not significantly alter ethanol self-administration or water intake when administered alone in the PVN but it completely blocked the effect of NPY (10 fmol) on ethanol intake. NPY infused in the PVN had no effect on ethanol self-administration when tested in rats that did not have a long history of ethanol self-administration. The doses of NPY tested produced no effect on food intake or body weight measured during the 24-h period after infusion in either ethanol-experienced or ethanol-inexperienced rats. These results indicate that elevation of NPY levels in the PVN potently increases ethanol self-administration and that this effect is mediated through NPY Y1 receptors
Effects of mGlu1-receptor blockade on ethanol self-administration in inbred alcohol-preferring rats
Estimating Allele Frequencies and Inbreeding Coefficients in K-Allele Models
Some of the methods of estimation of allele frequencies and inbreeding coefficients in a K-allele model are examined. A result that has long been assumed to be true is proved. That is, in the presence of inbreeding, the maximum likelihood estimators of the allele frequencies and of the inbreeding coefficient f do not in general equal their observed (or sample) values (except when K�=�2). A least-squares way of looking at the estimation problem is presented, and simulations are used to compare the three types of estimators (sample, maximum likelihood, and least-squares) in a 3-allele model. Probability generating functions are used to derive exact expressions for the bias of the sample estimator of f in a 2-allele model for any sample size, and those biases are calculated for a number of situations. Finally, an approximately unbiased estimator of the inbreeding coefficient when an allele is rare or common is proposed, and its bias is compared with that of the sample estimator and with that of an estimator proposed by Weir (1996).Hardy-Weinberg equilibrium, maximum likelihood, least-squares, probability generating function,