14,084 research outputs found
Lorentz violation in solar-neutrino oscillations
Solar-neutrino oscillations are considered using a massive model with
perturbative Lorentz violation. The adiabatic approximation is used to
calculate the effects of Lorentz violation to leading order. The results are
more compact than previous work involving vacuum oscillations, and are accurate
for small Lorentz-violating coefficients.Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 28-July 2, 201
The primary function of REM sleep
In this paper, the physiological features associated with the different stages of REM sleep and with what information processing researchers have called “effort” and “arousal” are compared. It is suggested that tonic REM sleep and effort involve an increase in the metabolism of cerebral glycogen, and phasic REM sleep and arousal involve the transfer of glucose from the body to the brain. Both stages of REM sleep seem to elevate cerebral glucose levels and likely result in increased ATP generation in some part(s) of the brain. It is noted that the functioning of the hippocampus depends heavily on ATP, and that this part of the brain becomes especially active during REM sleep. From this, although many details remain to be clarified, it seems clear that the primary function of REM sleep is to re-energize the brain
Estuarine Nitrifiers: New Players, Patterns and Processes
Ever since the first descriptions of ammonia-oxidizing Bacteria by Winogradsky in the late 1800s, the metabolic capability of aerobic ammonia oxidation has been restricted to a phylogenetically narrow group of bacteria. However, the recent discovery of ammonia-oxidizing Archaea has forced microbiologists and ecologists to re-evaluate long-held paradigms and the role of niche partitioning between bacterial and archaeal ammonia oxidizers. Much of the current research has been conducted in open ocean or terrestrial systems, where community patterns of archaeal and bacterial ammonia oxidizers are highly congruent. Studies of archaeal and bacterial ammonia oxidizers in estuarine systems, however, present a very different picture, with highly variable patterns of archaeal and bacterial ammonia oxidizer abundances. Although salinity is often identified as an important factor regulating abundance, distribution, and diversity of both archaeal and bacterial ammonia oxidizers, the data suggest that the variability in the observed patterns is likely not due to a simple salinity effect. Here we review current knowledge of ammonia oxidizers in estuaries and propose that because of their steep physico-chemical gradients, estuaries may serve as important natural laboratories in which to investigate the relationships between archaeal and bacterial ammonia oxidizers
Electron correlations and single-particle physics in the Integer Quantum Hall Effect
The compressibility of a two-dimensional electron system with spin in a
spatially correlated random potential and a quantizing magnetic field is
investigated. Electron-electron interaction is treated with the Hartree-Fock
method. Numerical results for the influences of interaction and disorder on the
compressibility as a function of the particle density and the strength of the
magnetic field are presented. Localization-delocalization transitions
associated with highly compressible region in the energy spectrum are found at
half-integer filling factors. Coulomb blockade effects are found near integer
fillings in the regions of low compressibility. Results are compared with
recent experiments.Comment: 4 pages, 2 figures, replaced with revised versio
Increased variability of microbial communities in restored salt marshes nearly 30 years after tidal flow restoration
We analyzed microbial diversity and community composition from four salt marsh sites that were impounded for 40–50 years and subsequently restored and four unimpounded sites in southeastern Connecticut over one growing season. Community composition and diversity were assessed by terminal restriction fragment length polymorphism (TRFLP) and sequence analysis of 16S ribosomal RNA (rRNA) genes. Our results indicated diverse communities, with sequences representing 14 different bacterial divisions. Proteobacteria, Bacteroidetes, and Planctomycetes dominated clone libraries from both restored and unimpounded sites. Multivariate analysis of the TRFLP data suggest significant site, sample date, and restoration status effects, but the exact causes of these effects are not clear. Composition of clone libraries and abundance of bacterial 16S rRNA genes were not significantly different between restored sites and unimpounded sites, but restored sites showed greater temporal and spatial variability of bacterial communities based on TRFLP profiles compared with unimpounded sites, and variability was greatest at sites more recently restored. In summary, our study suggests there may be long-lasting effects on stability of bacterial communities in restored salt marshes and raises questions about the resilience and ultimate recovery of the communities after chronic disturbance
A study of methods to predict and measure the transmission of sound through the walls of light aircraft. A survey of techniques for visualization of noise fields
A survey of the most widely used methods for visualizing acoustic phenomena is presented. Emphasis is placed on acoustic processes in the audible frequencies. Many visual problems are analyzed on computer graphic systems. A brief description of the current technology in computer graphics is included. The visualization technique survey will serve as basis for recommending an optimum scheme for displaying acoustic fields on computer graphic systems
Competition and Intervention in Sovereign Debt Markets
We investigate markets for defaultable sovereign debt in which even though there are many identical lenders and symmetric information (including no hidden actions), perfect competition does not obtain. When a private lender allows a sovereign country to increase its level of indebtedness, that lender implicitly imposes a default externality on others who have lent to that sovereign. That is, in the case where the borrower would be able to pay back the first loan in the absence of a second loan, the borrower may have a strong incentive to take both loans and default on both loans. When a lender has no control over the actions of other lenders, they must anticipate this behavior and devise a lending strategy that is consistent with the strategies not only of the sovereign borrower, but also of other lenders. We develop a model of this strategic lending behavior in the presence of default, and show that even though there are many competing lenders, the perfectly competitive outcome does not necessarily obtain. Moreover, the equilibrium can result in monopoly-like outcomes in prices and quantities. We also study the consequences of intervention in these markets by a seemingly benevolent international financial institution, and find that these interventions, though well-intentioned, can in some cases be welfare reducing for sovereign countries and welfare improving for private lenders.
Contact urticaria to giraffe hair
Background: Immediate-type hypersensitivity to animal proteins is a common problem in people occupationally exposed to animals. Methods: A 19-year-old female working as a voluntary zookeeper in her off-time suffered from hives on her forearms following contact to the fur of a giraffe. For diagnostic evaluation, skin prick tests, assessment of specific serum IgE antibodies, and basophil activation tests were performed. Results: Skin prick tests with a standard series of common aeroallergens were positive for various pollens. Prick testing with native materials was positive for extracts of hair from two different giraffe subspecies in the patient, but not in control subjects. By CAP-FEIA, no specific serum IgE antibodies to dander of a large variety of animals were found in the patient. In the basophil activation test, expression of the activation marker CD63 was induced by extract of giraffe hair on the cells from the patient, but not on those from unaffected controls. Conclusions: This patient suffers from an `exotic' immediate-type contact allergy to giraffe hair. Copyright (C) 2005 S. Karger AG, Basel
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