456 research outputs found
Limiting Carleman weights and anisotropic inverse problems
In this article we consider the anisotropic Calderon problem and related
inverse problems. The approach is based on limiting Carleman weights,
introduced in Kenig-Sjoestrand-Uhlmann (Ann. of Math. 2007) in the Euclidean
case. We characterize those Riemannian manifolds which admit limiting Carleman
weights, and give a complex geometrical optics construction for a class of such
manifolds. This is used to prove uniqueness results for anisotropic inverse
problems, via the attenuated geodesic X-ray transform. Earlier results in
dimension were restricted to real-analytic metrics.Comment: 58 page
Discrete Gauge Symmetries in Discrete MSSM-like Orientifolds
Motivated by the necessity of discrete Z_N symmetries in the MSSM to insure
baryon stability, we study the origin of discrete gauge symmetries from open
string sector U(1)'s in orientifolds based on rational conformal field theory.
By means of an explicit construction, we find an integral basis for the
couplings of axions and U(1) factors for all simple current MIPFs and
orientifolds of all 168 Gepner models, a total of 32990 distinct cases. We
discuss how the presence of discrete symmetries surviving as a subgroup of
broken U(1)'s can be derived using this basis. We apply this procedure to
models with MSSM chiral spectrum, concretely to all known U(3)xU(2)xU(1)xU(1)
and U(3)xSp(2)xU(1)xU(1) configurations with chiral bi-fundamentals, but no
chiral tensors, as well as some SU(5) GUT models. We find examples of models
with Z_2 (R-parity) and Z_3 symmetries that forbid certain B and/or L violating
MSSM couplings. Their presence is however relatively rare, at the level of a
few percent of all cases.Comment: 47 pages. References adde
Cardiovascular safety of celecoxib in acute myocardial infarction patients: a nested case-control study
The objective was to measure the impact of exposure to coxibs and non-steroidal antiinflammatory drugs (NSAID) on morbidity and mortality in older patients with acute myocardial infarction (AMI). A nested case-control study was carried out using an exhaustive population-based cohort of patients aged 66 years and older living in Quebec (Canada) who survived a hospitalization for AMI (ICD-9 410) between 1999 and 2002. The main variables were all-cause and cardiovascular (CV) death, subsequent hospital admission for AMI, and a composite end-point including recurrent AMI or CV death. Conditional logistic regressions were used to estimate the risk of mortality and morbidity. A total of 19,823 patients aged 66 years and older survived hospitalization for AMI in the province of Quebec between 1999 and 2002. After controlling for covariables, the risk of subsequent AMI and the risk of composite end-point were increased by the use of rofecoxib. The risk of subsequent AMI was particularly high for new rofecoxib users (HR 2.47, 95% CI 1.57–3.89). No increased risk was observed for celecoxib users. No increased risk of CV death was observed for patients exposed to coxibs or NSAIDs. Patients newly exposed to NSAIDs were at an increased risk of death (HR 2.22, 95% CI 1.30–3.77) and of composite end-point (HR 2.28, 95% CI 1.35–3.84). Users of rofecoxib and NSAIDs, but not celecoxib, were at an increased risk of recurrent AMI and of composite end-point. Surprisingly, no increased risk of CV death was observed. Further studies are needed to better understand these apparently contradictory results
Have we seen the geneticisation of society? Expectations and evidence
Abby Lippman’s geneticization thesis, of the early 1990s, argued and anticipated that with
the rise of genetics, increasing areas of social and health related activities would come to be
understood and defined in genetic terms leading to major changes in society, medicine and
health care. We review the considerable literature on geneticization and consider how the
concept stands both theoretically and empirically across scientific, clinical, popular and lay
discourse and practice. Social science scholarship indicates that relatively little of the original
claim of the geneticization thesis has been realised, highlighting the development of more
complex and dynamic accounts of disease in scientific discourse and the complexity of
relationships between bioscientific, clinical and lay understandings. This scholarship
represents a shift in social science understandings of the processes of sociotechnical change,
which have moved from rather simplistic linear models to an appreciation of disease
categories as multiply understood. Despite these shifts, we argue that a genetic imaginary
persists, which plays a performative role in driving investments in new gene-based
developments. Understanding the enduring power of this genetic imaginary and its
consequences remains a key task for the social sciences, one which treats ongoing genetic
expectations and predictions in a sceptical yet open way
Observation of Scaling Violations in Scaled Momentum Distributions at HERA
Charged particle production has been measured in deep inelastic scattering
(DIS) events over a large range of and using the ZEUS detector. The
evolution of the scaled momentum, , with in the range 10 to 1280
, has been investigated in the current fragmentation region of the Breit
frame. The results show clear evidence, in a single experiment, for scaling
violations in scaled momenta as a function of .Comment: 21 pages including 4 figures, to be published in Physics Letters B.
Two references adde
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS
We present the results of a search for new, heavy particles that decay at a
significant distance from their production point into a final state containing
charged hadrons in association with a high-momentum muon. The search is
conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV
and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS
detector operating at the Large Hadron Collider. Production of such particles
is expected in various scenarios of physics beyond the standard model. We
observe no signal and place limits on the production cross-section of
supersymmetric particles in an R-parity-violating scenario as a function of the
neutralino lifetime. Limits are presented for different squark and neutralino
masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final
version to appear in Physics Letters
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