5,553 research outputs found
Leptonic asymmetry in ttbar production at CDF
The leptonic asymmetry in semileptonic ttbar decays is measured with the CDF
detector using the full Tevatron Run II dataset, which corresponds to 9.4 fb^-1
of integrated luminosity. The measured asymmetry is extrapolated to the full
kinematic range and the measured value of A_FB^lep = 0.094^+0.032_-0.029 is
compared to the NLO prediction A_FB^lep = 0.038 +/- 0.003.Comment: 4 pages, 3 figures; talk given at Large Hadron Collider Physics
Conference (LHCP 2013), 13-18 May 2013, Barcelona, Spai
Numerical Evolution of Dynamic 3D Black Holes: Extracting Waves
We consider the numerical evolution of dynamic black hole initial data sets
with a full 3D, nonlinear evolution code. These data sets consist of single
black holes distorted by strong gravitational waves, and mimic the late stages
of coalescing black holes. Through comparison with results from well
established axisymmetric codes, we show that these dynamic black holes can be
accurately evolved. In particular, we show that with present computational
resources and techniques, the process of excitation and ringdown of the black
hole can be evolved, and one can now extract accurately the gravitational waves
emitted from the 3D Cartesian metric functions, even though they may be buried
in the metric at levels on the order of and below. Waveforms for both
the and the much more difficult modes are computed and
compared with axisymmetric calculations. In addition to exploring the physics
of distorted black hole data sets, and showing the extent to which the waves
can be accurately extracted, these results also provide important testbeds for
all fully nonlinear numerical codes designed to evolve black hole spacetimes in
3D, whether they use singularity avoiding slicings, apparent horizon boundary
conditions, or other evolution methods.Comment: 9 pages, 3 figures, LaTe
Goodness of fit in models for mortality data
Mortality data on an aggregate level are characterized by very large sample sizes. For this
reason, uninformative outcomes are evident in common Goodness-of-Fit measures. In this
paper we propose a new measure that allows comparison of different mortality models even for
large sample sizes. Particularly, we develop a measure which uses a null model specifically
designed for mortality data. Several simulation studies and actual applications will demonstrate
the performances of this new measure with special emphasis on demographic models and Pspline
approach
Isolated Subtle Neurological Abnormalities in Mild Cognitive Impairment Types
Background: Isolated, subtle neurological abnormalities (ISNA) are commonly seen in aging and have been related to cerebral small vessel disease (SVD) and subcortical atrophy in neurologically and cognitively healthy aging subjects. Objective: To investigate the frequency of ISNA in different mild cognitive impairment (MCI) types and to evaluate for each MCI type, the crosssectional relation between ISNA and white matter hyperintensities (WMH), lacunes, caudate atrophy, and ventricular enlargement. Methods: One thousand two hundred fifty subjects with different MCI types were included in the analysis and underwent brain magnetic resonance imaging. WMHs were assessed through two visual rating scales. Lacunes were also rated. Atrophy of the caudate nuclei and ventricular enlargement were assessed through the bicaudate ratio (BCr) and the lateral ventricles to brain ratio (LVBr), respectively. Apolipoprotein E (APOE) genotypes were also assessed. The routine neurological examination was used to evaluate ISNAs that were clustered as central-based signs, cerebellar-based signs, and primitive reflexes. The items of Part-III of the Unified Parkinson’s Disease Rating Scale were used to evaluate ISNAs that were clustered as mild parkinsonian signs. Associations of ISNAs with imaging findings were determined through logistic regression analysis. Results: The ISNAs increase with the age and are present in all MCI types, particularly in those multiple domains, and carrying the APOE ϵ4 allele, and are associated with WMH, lacunes, BCr, and LVBr. Conclusion: This study demonstrates that cortical and subcortical vascular and atrophic processes contribute to ISNAs. Long prospective population-based studies are needed to disentangle the role of ISNAs in the conversion from MCI to dementia
Reusable high-temperature heat pipes and heat pipe panels
A reusable, durable heat pipe which is capable of operating at temperatures up to about 3000 F in an oxidizing environment and at temperatures above 3000 F in an inert or vacuum environment is produced by embedding a refractory metal pipe within a carbon-carbon composite structure. A reusable, durable heat pipe panel is made from an array of refractory-metal pipes spaced from each other. The reusable, durable, heat-pipe is employed to fabricate a hypersonic vehicle leading edge and nose cap
Three Dimensional Distorted Black Holes: Initial Data and Evolution
We present a new class of 3D black hole initial data sets for numerical
relativity. These data sets go beyond the axisymmetric, ``gravity wave plus
rotating black hole'' single black hole data sets by creating a dynamic,
distorted hole with adjustable distortion parameters in 3D. These data sets
extend our existing test beds for 3D numerical relativity, representing the
late stages of binary black hole collisions resulting from on-axis collision or
3D spiralling coalescence, and should provide insight into the physics of such
systems. We describe the construction of these sets, the properties for a
number of example cases, and report on progress evolving them.Comment: 3 pages, 2 postscript figures, LaTeX, uses mprocl.sty (available at
http://shemesh.fiz.huji.ac.il/MG8/submission.html) To appear in the
proceedings of the Marcel Grossmann 8 (Jerusalem, 1997
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