2,609 research outputs found
Higher dimensional supersymmetry in 4D superspace
We present an explicit formulation of supersymmetric Yang-Mills theories from
\D= 5 to 10 dimensions in the familiar \N=1,\D=4 superspace. This provides
the rules for globally supersymmetric model building with extra dimensions and
in particular allows us to simply write down SUSY preserving
interactions between bulk fields and fields localized on branes. We present a
few applications of the formalism by way of illustration, including
supersymmetric ``shining'' of bulk fields, orbifolds and localization of chiral
fermions, anomaly inflow and super-Chern-Simons theories.Comment: Typos corrected. Added reference to early work by Marcus, Sagnotti
and Siegel and a term to the non-Abelian Lagrangian for D>5 formally needed
for gauge invariance. The results however remain unchange
About the stability of the dodecatoplet
A new investigation is done of the possibility of binding the "dodecatoplet",
a system of six top quarks and six top antiquarks, using the Yukawa potential
mediated by Higgs exchange. A simple variational method gives a upper bound
close to that recently estimated in a mean-field calculation. It is
supplemented by a lower bound provided by identities among the Hamiltonians
describing the system and its subsystems.Comment: 5 pages, two figures merged, refs. added, typos correcte
Application of PCR to a clinical and environmental investigation of a case of equine botulism
PCR for the detection of botulinum neurotoxin gene types A to E was used in the investigation of a case of equine botulism. Samples from a foal diagnosed with toxicoinfectious botulism in 1985 were reanalyzed by PCR and the mouse bioassay in conjunction with an environmental survey. Neurotoxin B was detected by mouse bioassay in culture enrichments of serum, spleen, feces, and intestinal contents. PCR results compared well with mouse bioassay results, detecting type B neurotoxin genes in these samples and also in a liver sample. Other neurotoxin types were not detected by either test. Clostridium botulinum type B was shown to be prevalent in soils collected from the area in which the foal was raised. Four methods were used to test for the presence of botulinum neurotoxin-producing organisms in 66 soil samples taken within a 5-km radius: PCR and agarose gel electrophoresis (types A to E), PCR and an enzyme-linked assay (type B), hybridization of crude alkaline cell lysates with a type B-specific probe, and the mouse bioassay (all types). Fewer soil samples were positive for C. botulinum type B by the mouse bioassay (15%) than by any of the DNA-based detection systems. Hybridization of a type B-specific probe to DNA dot blots (26% of the samples were positive) and PCR-enzyme-linked assay (77% of the samples were positive) were used for the rapid analysis of large numbers of samples, with sensitivity limits of 3 x 10(6) and 3,000 cells, respectively. Conventional detection of PCR products by gel electrophoresis was the most sensitive method (300-cell limit), and in the present environmental survey, neurotoxin B genes only were detected in 94% of the samples
Presence of the brown fat-specific mitochondrial uncoupling protein and iodothyronine 5'-deiodinase activity in subcutaneous adipose tissue of neonatal lambs
AbstractSubcutaneous adipose tissue of neonatal lambs has been examined for the presence of markers diagnostic of thermogenic brown fat. Uncoupling protein, uncoupling protein mRNA, and iodothyronine 5'-deiodinase activity were each detected in subcutaneous adipose tissue, as well as in the major internal fat depot (perirenal), of newborn lambs. These brown fat markers were not present, however, in adipose tissue of adult sheep. It is concluded that subcutaneous fat in newborn lambs is functionally âbrownâ, and similar to the internal fat; subcutaneous and internal adipose tissues follow a similar developmental path - from âbrownâ to âwhiteâ
Charge Symmetry Violation Corrections to Determination of the Weinberg Angle in Neutrino Reactions
We show that the correction to the Paschos-Wolfenstein relation associated
with charge symmetry violation in the valence quark distributions is
essentially model independent. It is proportional to a ratio of quark momenta
that is independent of Q^2. This result provides a natural explanation of the
surprisingly good agreement found between our earlier estimates within several
different models. When applied to the recent NuTeV measurement, this effect
significantly reduces the discrepancy with other determinations of the Weinberg
angle.Comment: 7 pages, no figures; expanded discussion of N.ne.Z correction
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