28 research outputs found
Supersymmetric non-linear sigma-models with boundaries revisited
We study two-dimensional supersymmetric non-linear sigma-models with
boundaries. We derive the most general family of boundary conditions in the
non-supersymmetric case. Next we show that no further conditions arise when
passing to the N=1 model. We present a manifest N=1 off-shell formulation. The
analysis is greatly simplified compared to previous studies and there is no
need to introduce non-local superspaces nor to go (partially) on-shell. Whether
or not torsion is present does not modify the discussion. Subsequently, we
determine under which conditions a second supersymmetry exists. As for the case
without boundaries, two covariantly constant complex structures are needed.
However, because of the presence of the boundary, one gets expressed in terms
of the other one and the remainder of the geometric data. Finally we recast
some of our results in N=2 superspace and discuss applications.Comment: LaTeX, 23 page
Koebe 1/4-Theorem and Inequalities in N=2 Super-QCD
The critical curve on which ,
, determines hyperbolic domains whose Poincar\'e metric is
constructed in terms of and . We describe in a parametric
form related to a Schwarzian equation and prove new relations for Super
Yang-Mills. In particular, using the Koebe 1/4-theorem and Schwarz's
lemma, we obtain inequalities involving , and , which seem related
to the Renormalization Group. Furthermore, we obtain a closed form for the
prepotential as function of . Finally, we show that , where is the one-loop coefficient of the beta
function.Comment: 11 pages, LaTex file, Expanded version: new results, technical
details explained, misprints corrected and references adde
On the covariant quantization of tensionless bosonic strings in AdS spacetime
The covariant quantization of the tensionless free bosonic (open and closed)
strings in AdS spaces is obtained. This is done by representing the AdS space
as an hyperboloid in a flat auxiliary space and by studying the resulting
string constrained hamiltonian system in the tensionless limit. It turns out
that the constraint algebra simplifies in the tensionless case in such a way
that the closed BRST quantization can be formulated and the theory admits then
an explicit covariant quantization scheme. This holds for any value of the
dimension of the AdS space.Comment: 1+16 pages; v4 two clarifications adde
Decay of Unstable D-branes with Electric Field
Using the techniques of two dimensional conformal field theory we construct
time dependent classical solutions in open string theory describing the decay
of an unstable D-brane in the presence of background electric field, and
explicitly evaluate the time dependence of the energy momentum tensor and the
fundamental string charge density associated with this solution. The final
decay product can be interpreted as a combination of stretched fundamental
strings and tachyon matter.Comment: 35 pages, LaTe
Isolation and genotyping of Clostridium perfringens and Clostridium difficile in Capuchin Monkeys (Sapajus spp.)
New insights into the genetic etiology of Alzheimer's disease and related dementias
Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE Δ4 allele
A genome-wide gene-environment interaction study of breast cancer risk for women of European ancestry
Background
Genome-wide studies of geneâenvironment interactions (GĂE) may identify variants associated with disease risk in conjunction with lifestyle/environmental exposures. We conducted a genome-wide GĂE analysis ofâ~â7.6 million common variants and seven lifestyle/environmental risk factors for breast cancer risk overall and for estrogen receptor positive (ERâ+) breast cancer.
Methods
Analyses were conducted using 72,285 breast cancer cases and 80,354 controls of European ancestry from the Breast Cancer Association Consortium. Geneâenvironment interactions were evaluated using standard unconditional logistic regression models and likelihood ratio tests for breast cancer risk overall and for ERâ+âbreast cancer. Bayesian False Discovery Probability was employed to assess the noteworthiness of each SNP-risk factor pairs.
Results
Assuming a 1âĂâ10â5 prior probability of a true association for each SNP-risk factor pairs and a Bayesian False Discovery Probabilityâ<â15%, we identified two independent SNP-risk factor pairs: rs80018847(9p13)-LINGO2 and adult height in association with overall breast cancer risk (ORintâ=â0.94, 95% CI 0.92â0.96), and rs4770552(13q12)-SPATA13 and age at menarche for ERâ+âbreast cancer risk (ORintâ=â0.91, 95% CI 0.88â0.94).
Conclusions
Overall, the contribution of GĂE interactions to the heritability of breast cancer is very small. At the population level, multiplicative GĂE interactions do not make an important contribution to risk prediction in breast cancer