133 research outputs found
Calculations for Mirror Symmetry with D-branes
We study normal functions capturing D-brane superpotentials on several one-
and two-parameter Calabi-Yau hypersurfaces and complete intersections in
weighted projective space. We calculate in the B-model and interpret the
results using mirror symmetry in the large volume regime, albeit without
identifying the precise A-model geometry in all cases. We identify new classes
of extensions of Picard-Fuchs equations, as well as a novel type of topology
changing phase transition involving quantum D-branes. A 4-d domain wall which
is obtained in one region of closed string moduli space from wrapping a
four-chain interpolating between two Lagrangian submanifolds is, for other
values of the parameters, represented by a disk ending on a single Lagrangian.Comment: 42 page
Mirror Symmetry for Toric Branes on Compact Hypersurfaces
We use toric geometry to study open string mirror symmetry on compact
Calabi-Yau manifolds. For a mirror pair of toric branes on a mirror pair of
toric hypersurfaces we derive a canonical hypergeometric system of differential
equations, whose solutions determine the open/closed string mirror maps and the
partition functions for spheres and discs. We define a linear sigma model for
the brane geometry and describe a correspondence between dual toric polyhedra
and toric brane geometries. The method is applied to study examples with
obstructed and classically unobstructed brane moduli at various points in the
deformation space. Computing the instanton expansion at large volume in the
flat coordinates on the open/closed deformation space we obtain predictions for
enumerative invariants.Comment: 36 pages, references adde
Endemic fungal infections in solid organ and hematopoietic cell transplant recipients enrolled in the Transplant‐Associated Infection Surveillance Network ( TRANSNET )
Background Invasive fungal infections are a major cause of morbidity and mortality among solid organ transplant ( SOT ) and hematopoietic cell transplant ( HCT ) recipients, but few data have been reported on the epidemiology of endemic fungal infections in these populations. Methods Fifteen institutions belonging to the Transplant‐Associated Infection Surveillance Network prospectively enrolled SOT and HCT recipients with histoplasmosis, blastomycosis, or coccidioidomycosis occurring between March 2001 and March 2006. Results A total of 70 patients (64 SOT recipients and 6 HCT recipients) had infection with an endemic mycosis, including 52 with histoplasmosis, 9 with blastomycosis, and 9 with coccidioidomycosis. The 12‐month cumulative incidence rate among SOT recipients for histoplasmosis was 0.102%. Occurrence of infection was bimodal; 28 (40%) infections occurred in the first 6 months post transplantation, and 24 (34%) occurred between 2 and 11 years post transplantation. Three patients were documented to have acquired infection from the donor organ. Seven SOT recipients with histoplasmosis and 3 with coccidioidomycosis died (16%); no HCT recipient died. Conclusions This 5‐year multicenter prospective surveillance study found that endemic mycoses occur uncommonly in SOT and HCT recipients, and that the period at risk extends for years after transplantation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106980/1/tid12186.pd
A Measurement of Time-Averaged Aerosol Optical Depth using Air-Showers Observed in Stereo by HiRes
Air fluorescence measurements of cosmic ray energy must be corrected for
attenuation of the atmosphere. In this paper we show that the air-showers
themselves can yield a measurement of the aerosol attenuation in terms of
optical depth, time-averaged over extended periods. Although the technique
lacks statistical power to make the critical hourly measurements that only
specialized active instruments can achieve, we note the technique does not
depend on absolute calibration of the detector hardware, and requires no
additional equipment beyond the fluorescence detectors that observe the air
showers. This paper describes the technique, and presents results based on
analysis of 1258 air-showers observed in stereo by the High Resolution Fly's
Eye over a four year span.Comment: 7 pages, 3 figures, accepted for publication by Astroparticle Physics
Journa
A Likelihood Method for Measuring the Ultrahigh Energy Cosmic Ray Composition
Air fluorescence detectors traditionally determine the dominant chemical
composit ion of the ultrahigh energy cosmic ray flux by comparing the averaged
slant depth of the shower maximum, , as a function of energy to the
slant depths expect ed for various hypothesized primaries. In this paper, we
present a method to make a direct measurement of the expected mean number of
protons and iron by comparing the shap es of the expected
distributions to the distribution for data. The advantages of this method
includes the use of information of the full distribution and its ability to
calculate a flux for various cosmic ray compositi ons. The same method can be
expanded to marginalize uncertainties due to choice of spectra, hadronic models
and atmospheric parameters. We demonstrate the technique with independent
simulated data samples from a parent sample of protons and iron. We accurately
predict the number of protons and iron in the parent sample and show that the
uncertainties are meaningful.Comment: 11 figures, 22 pages, accepted by Astroparticle Physic
Alternative Methods to Finding Patterns in HiRes Stereo Data
In this paper Ultra High Energy Cosmic Rays UHECRs data observed by the HiRes
fluorescence detector in stereo mode is analyzed to search for events in the
sky with an arrival direction lying on a great circle. Such structure is known
as the arc structure. The arc structure is expected when the charged cosmic
rays pass through the galactic magnetic field. The arcs searched for could
represent a broad or a small scale anisotropy depending on the proposed source
model for the UHECRs. The Arcs in this paper are looked for using Hough
transform were Hough transform is a technique used to looking for patterns in
images. No statistically significant arcs were found in this study
Spectrofluorimetric determination of amlodipine in human plasma without derivatization
The genetic architecture of the human cerebral cortex
INTRODUCTION
The cerebral cortex underlies our complex cognitive capabilities. Variations in human cortical surface area and thickness are associated with neurological, psychological, and behavioral traits and can be measured in vivo by magnetic resonance imaging (MRI). Studies in model organisms have identified genes that influence cortical structure, but little is known about common genetic variants that affect human cortical structure.
RATIONALE
To identify genetic variants associated with human cortical structure at both global and regional levels, we conducted a genome-wide association meta-analysis of brain MRI data from 51,665 individuals across 60 cohorts. We analyzed the surface area and average thickness of the whole cortex and 34 cortical regions with known functional specializations.
RESULTS
We identified 306 nominally genome-wide significant loci (P < 5 × 10−8) associated with cortical structure in a discovery sample of 33,992 participants of European ancestry. Of the 299 loci for which replication data were available, 241 loci influencing surface area and 14 influencing thickness remained significant after replication, with 199 loci passing multiple testing correction (P < 8.3 × 10−10; 187 influencing surface area and 12 influencing thickness).
Common genetic variants explained 34% (SE = 3%) of the variation in total surface area and 26% (SE = 2%) in average thickness; surface area and thickness showed a negative genetic correlation (rG = −0.32, SE = 0.05, P = 6.5 × 10−12), which suggests that genetic influences have opposing effects on surface area and thickness. Bioinformatic analyses showed that total surface area is influenced by genetic variants that alter gene regulatory activity in neural progenitor cells during fetal development. By contrast, average thickness is influenced by active regulatory elements in adult brain samples, which may reflect processes that occur after mid-fetal development, such as myelination, branching, or pruning. When considered together, these results support the radial unit hypothesis that different developmental mechanisms promote surface area expansion and increases in thickness.
To identify specific genetic influences on individual cortical regions, we controlled for global measures (total surface area or average thickness) in the regional analyses. After multiple testing correction, we identified 175 loci that influence regional surface area and 10 that influence regional thickness. Loci that affect regional surface area cluster near genes involved in the Wnt signaling pathway, which is known to influence areal identity.
We observed significant positive genetic correlations and evidence of bidirectional causation of total surface area with both general cognitive functioning and educational attainment. We found additional positive genetic correlations between total surface area and Parkinson’s disease but did not find evidence of causation. Negative genetic correlations were evident between total surface area and insomnia, attention deficit hyperactivity disorder, depressive symptoms, major depressive disorder, and neuroticism.
CONCLUSION
This large-scale collaborative work enhances our understanding of the genetic architecture of the human cerebral cortex and its regional patterning. The highly polygenic architecture of the cortex suggests that distinct genes are involved in the development of specific cortical areas. Moreover, we find evidence that brain structure is a key phenotype along the causal pathway that leads from genetic variation to differences in general cognitive function
Angular analysis of the decay B0→K*0μ+μ- from pp collisions at s=8 TeV
The angular distributions and the differential branching fraction of the decay B0→K⁎(892)0μ+μ− are studied using data corresponding to an integrated luminosity of 20.5 fb −1 collected with the CMS detector at the LHC in pp collisions at s=8 TeV . From 1430 signal decays, the forward–backward asymmetry of the muons, the K⁎(892)0 longitudinal polarization fraction, and the differential branching fraction are determined as a function of the dimuon invariant mass squared. The measurements are among the most precise to date and are in good agreement with standard model predictions
Search for the production of an excited bottom quark decaying to tW in proton-proton collisions at root s=8 TeV
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