1,158 research outputs found
One-Loop Renormalization of Lorentz-Violating Electrodynamics
We show that the general Lorentz- and CPT-violating extension of quantum
electrodynamics is one-loop renormalizable. The one-loop Lorentz-violating beta
functions are obtained, and the running of the coefficients for Lorentz and CPT
violation is determined. Some implications for theory and experiment are
discussed.Comment: 12 pages, accepted for publication in Physical Review
Homozygosity for a missense mutation in the 67 kDa isoform of glutamate decarboxylase in a family with autosomal recessive spastic cerebral palsy: parallels with Stiff-Person Syndrome and other movement disorders
Background
Cerebral palsy (CP) is an heterogeneous group of neurological disorders of movement and/or posture, with an estimated incidence of 1 in 1000 live births. Non-progressive forms of symmetrical, spastic CP have been identified, which show a Mendelian autosomal recessive pattern of inheritance. We recently described the mapping of a recessive spastic CP locus to a 5 cM chromosomal region located at 2q24-31.1, in rare consanguineous families.
Methods
Here we present data that refine this locus to a 0.5 cM region, flanked by the microsatellite markers D2S2345 and D2S326. The minimal region contains the candidate gene GAD1, which encodes a glutamate decarboxylase isoform (GAD67), involved in conversion of the amino acid and excitatory neurotransmitter glutamate to the inhibitory neurotransmitter γ-aminobutyric acid (GABA).
Results
A novel amino acid mis-sense mutation in GAD67 was detected, which segregated with CP in affected individuals.
Conclusions
This result is interesting because auto-antibodies to GAD67 and the more widely studied GAD65 homologue encoded by the GAD2 gene, are described in patients with Stiff-Person Syndrome (SPS), epilepsy, cerebellar ataxia and Batten disease. Further investigation seems merited of the possibility that variation in the GAD1 sequence, potentially affecting glutamate/GABA ratios, may underlie this form of spastic CP, given the presence of anti-GAD antibodies in SPS and the recognised excitotoxicity of glutamate in various contexts
A Multiwavelength Study of Stephan's Quintet
Stephan's Quintet (SQ) is a compact group that we find in an atypical moment
when a high velocity intruder is passing through it. The intrusion is
particularly interesting because a previous intruder had stripped most of the
gas from the group members. This debris field was shocked in the ongoing
collision with the new intruder. This evolutionary history agrees well with
observations and explains how a strongly interacting system can show low levels
of star formation. We present new multiwavelength data including previously
unpublished ROSAT X-ray, Ha interference filter/FP, ISO MIR/FIR and radio line
and continuum images. These observations and previously published data provide
new insights as well as support for some previous hypotheses. 1) FP and HI
velocities allow us to unambiguously distinguish between gas associated with SQ
and the new intruder.
2) Most detected emission regions are found in the remnant ISM of the NI
which allows us to infer its size and present physical state. 3) The few
emission regions associated with the stripped ISM of SQ include the best
candidate tidal dwarf galaxy. 4) Multiwavelength data suggest that strong
MIR/FIR emission from the Seyfert 2 nucleus of NGC7319 comes from dust heated
directly by a power-law continuum rather than a starburst. 5) The
correspondance between extended X-ray/radio continuum/forbidden optical
emission confirms the existence of a large scale shock in SQ.Comment: In press in AJ. 44 pages, 10 Postscript figures, uses aastex.st
Planning Framework Options for The Massachusetts Ocean Plan (DRAFT)
The Massachusetts Ocean Partnership (MOP) Planning Frameworks Team, in consultation with the Massachusetts Executive Office of Energy and Environmental Affairs (EEA), and based on collective experience and a review of ocean, coastal and resource management programs from the US and other countries, suggests that nine elements are essential components of the framework for the Massachusetts Ocean Plan and its implementation. While management plans and programs generally have these elements in common, there are a range of options for carrying out each program component. These options were presented to structure and inform the development of the Massachusetts Ocean Plan. For the most part, the range of options represents those that were considered to be appropriate under the Commonwealth’s existing legal and administrative structure and responsive to the requirements of the Massachusetts Ocean Act. However, the general concepts these options represent are likely to be transferable to other jurisdictions (especially in the United States) and can inform future ocean management and planning in Massachusetts. Additionally, options or their core elements can be combined to create additional alternatives within one of the nine planning components
Quantum Fields and Extended Objects in Space-Times with Constant Curvature Spatial Section
The heat-kernel expansion and -regularization techniques for quantum
field theory and extended objects on curved space-times are reviewed. In
particular, ultrastatic space-times with spatial section consisting in manifold
with constant curvature are discussed in detail. Several mathematical results,
relevant to physical applications are presented, including exact solutions of
the heat-kernel equation, a simple exposition of hyperbolic geometry and an
elementary derivation of the Selberg trace formula. With regards to the
physical applications, the vacuum energy for scalar fields, the one-loop
renormalization of a self-interacting scalar field theory on a hyperbolic
space-time, with a discussion on the topological symmetry breaking, the finite
temperature effects and the Bose-Einstein condensation, are considered. Some
attempts to generalize the results to extended objects are also presented,
including some remarks on path integral quantization, asymptotic properties of
extended objects and a novel representation for the one-loop (super)string free
energy.Comment: Latex file, 122 page
Search for CP Violation in the Decay Z -> b (b bar) g
About three million hadronic decays of the Z collected by ALEPH in the years
1991-1994 are used to search for anomalous CP violation beyond the Standard
Model in the decay Z -> b \bar{b} g. The study is performed by analyzing
angular correlations between the two quarks and the gluon in three-jet events
and by measuring the differential two-jet rate. No signal of CP violation is
found. For the combinations of anomalous CP violating couplings, and , limits of \hat{h}_b < 0.59h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st
Mammostrat® as a tool to stratify breast cancer patients at risk of recurrence during endocrine therapy
Emerging Technologies for the Detection of Rabies Virus: Challenges and Hopes in the 21st Century
The diagnosis of rabies is routinely based on clinical and epidemiological information, especially when exposures are reported in rabies-endemic countries. Diagnostic tests using conventional assays that appear to be negative, even when undertaken late in the disease and despite the clinical diagnosis, have a tendency, at times, to be unreliable. These tests are rarely optimal and entirely dependent on the nature and quality of the sample supplied. In the course of the past three decades, the application of molecular biology has aided in the development of tests that result in a more rapid detection of rabies virus. These tests enable viral strain identification from clinical specimens. Currently, there are a number of molecular tests that can be used to complement conventional tests in rabies diagnosis. Indeed the challenges in the 21st century for the development of rabies diagnostics are not of a technical nature; these tests are available now. The challenges in the 21st century for diagnostic test developers are two-fold: firstly, to achieve internationally accepted validation of a test that will then lead to its acceptance by organisations globally. Secondly, the areas of the world where such tests are needed are mainly in developing regions where financial and logistical barriers prevent their implementation. Although developing countries with a poor healthcare infrastructure recognise that molecular-based diagnostic assays will be unaffordable for routine use, the cost/benefit ratio should still be measured. Adoption of rapid and affordable rabies diagnostic tests for use in developing countries highlights the importance of sharing and transferring technology through laboratory twinning between the developed and the developing countries. Importantly for developing countries, the benefit of molecular methods as tools is the capability for a differential diagnosis of human diseases that present with similar clinical symptoms. Antemortem testing for human rabies is now possible using molecular techniques. These barriers are not insurmountable and it is our expectation that if such tests are accepted and implemented where they are most needed, they will provide substantial improvements for rabies diagnosis and surveillance. The advent of molecular biology and new technological initiatives that combine advances in biology with other disciplines will support the development of techniques capable of high throughput testing with a low turnaround time for rabies diagnosis
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