1,365 research outputs found
Jet properties from di-hadron correlations in p+p collisions at s**(1/2) = 200-GeV
An analysis of high pT hadron spectra associated with high pT
particles in p+p collisions at s**(1/2) = 200-GeV is presented. The shape of
the azimuthal angular correlation is used to determine the value of partonic
intrinsic momentum \sqrt{\left} = 2.68 \pm 0.07(\rm stat) \pm
0.34(\rm sys) GeV/c. The effect of kT-smearing of inclusive cross
section is discussed.Comment: To appear in the proceedings of 2nd International Conference on Hard
and Electromagnetic Probes of High-Energy Nuclear Collisions (Hard Probes
2006), Asilomar, Pacific Grove, California, 9-16 Jun 200
Collisional energy loss and the suppression of high hadrons
We calculate nuclear suppression factor () for light hadrons by
taking only the elastic processes and argue that in the measured domain
of RHIC, collisional rather than the radiative processes is the dominant
mechanism for partonic energy loss.Comment: Presented at the international conference on strong and electroweak
matter 2006, May 10-13, Brookhaven National Laborator
STAR inner tracking upgrade - A performance study
Anisotropic flow measurements have demonstrated development of partonic
collectivity in Au+Au collisions at RHIC. To understand the
partonic EOS, thermalization must be addressed. Collective motion of
heavy-flavor (c,b) quarks can be used to indicate the degree of thermalization
of the light-flavor quarks (u,d,s). Measurement of heavy-flavor quark
collectivity requires direct reconstruction of heavy-flavor hadrons in the low
\pt region. Measurement of open charm spectra to high \pt can be used to
investigate heavy-quark energy loss and medium properties. The Heavy Flavor
Tracker (HFT), a proposed upgrade to the STAR experiment at midrapidity, will
measure of open-charm hadrons to very low \pt by reconstructing their
displaced decay vertices. The innermost part of the HFT is the PIXEL detector
(made of two low mass monolithic active pixel sensor layers), which delivers a
high precision position measurement close to the collision vertex. The
Intermediate Silicon Tracker (IST), a 1-layer strip detector, is essential to
improve hit identification in the PIXEL detector when running at full RHIC-II
luminosity. Using a full GEANT simulation, open charm measurement capabilities
of STAR with the HFT will be shown. Its performance in a broad \pt range will
be demonstrated on (\pt > 0.5\mathrm{GeV}/c) and
(\pt < 10\mathrm{GeV}/c) measurements of \D meson. Results of
reconstruction of \Lc baryon in heavy-ion collisions are presented.Comment: to appear in EPJ C (Hot Quarks 2008 conference volume
EDS tomographic reconstruction regularized by total nuclear variation joined with HAADF-STEM tomography
Energy-dispersive X-ray spectroscopy (EDS) tomography is an advanced technique to characterize compositional information for nanostructures in three dimensions (3D). However, the application is hindered by the poor image quality caused by the low signal-to-noise ratios and the limited number of tilts, which are fundamentally limited by the insufficient number of X-ray counts. In this paper, we explore how to make accurate EDS reconstructions from such data. We propose to augment EDS tomography by joining with it a more accurate high-angle annular dark-field STEM (HAADF-STEM) tomographic reconstruction, for which usually a larger number of tilt images are feasible. This augmentation is realized through total nuclear variation (TNV) regularization, which encourages the joint EDS and HAADF reconstructions to have not only sparse gradients but also common edges and parallel (or antiparallel) gradients. Our experiments show that reconstruction images are more accurate compared to the non-regularized and the total variation regularized reconstructions, even when the number of tilts is small or the X-ray counts are low
Improving ICD-based semantic similarity by accounting for varying degrees of comorbidity
Finding similar patients is a common objective in precision medicine,
facilitating treatment outcome assessment and clinical decision support.
Choosing widely-available patient features and appropriate mathematical methods
for similarity calculations is crucial. International Statistical
Classification of Diseases and Related Health Problems (ICD) codes are used
worldwide to encode diseases and are available for nearly all patients.
Aggregated as sets consisting of primary and secondary diagnoses they can
display a degree of comorbidity and reveal comorbidity patterns. It is possible
to compute the similarity of patients based on their ICD codes by using
semantic similarity algorithms. These algorithms have been traditionally
evaluated using a single-term expert rated data set.
However, real-word patient data often display varying degrees of documented
comorbidities that might impair algorithm performance. To account for this, we
present a scale term that considers documented comorbidity-variance. In this
work, we compared the performance of 80 combinations of established algorithms
in terms of semantic similarity based on ICD-code sets. The sets have been
extracted from patients with a C25.X (pancreatic cancer) primary diagnosis and
provide a variety of different combinations of ICD-codes. Using our scale term
we yielded the best results with a combination of level-based information
content, Leacock & Chodorow concept similarity and bipartite graph matching for
the set similarities reaching a correlation of 0.75 with our expert's ground
truth. Our results highlight the importance of accounting for comorbidity
variance while demonstrating how well current semantic similarity algorithms
perform.Comment: 11 pages, 6 figures, 1 tabl
- …