1,517 research outputs found
Classification of fracture and non-fracture groups by analysis of coherent X-ray scatter
Osteoporotic fractures present a significant social and economic burden, which is set to rise commensurately with the aging population. Greater understanding of the physicochemical differences between osteoporotic and normal conditions will facilitate the development of diagnostic technologies with increased performance and treatments with increased efficacy. Using coherent X-ray scattering we have evaluated a population of 108 ex vivo human bone samples comprised of non-fracture and fracture groups. Principal component fed linear discriminant analysis was used to develop a classification model to discern each condition resulting in a sensitivity and specificity of 93% and 91%, respectively. Evaluating the coherent X-ray scatter differences from each condition supports the hypothesis that a causal physicochemical change has occurred in the fracture group. This work is a critical step along the path towards developing an in vivo diagnostic tool for fracture risk prediction
Precision Measurement of the Mass of the h_c(1P1) State of Charmonium
A precision measurement of the mass of the h_c(1P1) state of charmonium has
been made using a sample of 24.5 million psi(2S) events produced in e+e-
annihilation at CESR. The reaction used was psi(2S) -> pi0 h_c, pi0 -> gamma
gamma, h_c -> gamma eta_c, and the reaction products were detected in the
CLEO-c detector.
Data have been analyzed both for the inclusive reaction and for the exclusive
reactions in which eta_c decays are reconstructed in fifteen hadronic decay
channels. Consistent results are obtained in the two analyses. The averaged
results of the present measurements are M(h_c)=3525.28+-0.19 (stat)+-0.12(syst)
MeV, and B(psi(2S) -> pi0 h_c)xB(h_c -> gamma eta_c)= (4.19+-0.32+-0.45)x10^-4.
Using the 3PJ centroid mass, Delta M_hf(1P)= - M(h_c) =
+0.02+-0.19+-0.13 MeV.Comment: 9 pages, available through http://www.lns.cornell.edu/public/CLNS/,
submitted to PR
Precision Measurement of B(D+ -> mu+ nu) and the Pseudoscalar Decay Constant fD+
We measure the branching ratio of the purely leptonic decay of the D+ meson
with unprecedented precision as B(D+ -> mu+ nu) = (3.82 +/- 0.32 +/-
0.09)x10^(-4), using 818/pb of data taken on the psi(3770) resonance with the
CLEO-c detector at the CESR collider. We use this determination to derive a
value for the pseudoscalar decay constant fD+, combining with measurements of
the D+ lifetime and assuming |Vcd| = |Vus|. We find fD+ = (205.8 +/- 8.5 +/-
2.5) MeV. The decay rate asymmetry [B(D+ -> mu+ nu)-B(D- -> mu- nu)]/[B(D+ ->
mu+ nu)+B(D- -> mu- nu)] = 0.08 +/- 0.08, consistent with no CP violation. We
also set 90% confidence level upper limits on B(D+ -> tau+ nu) < 1.2x10^(-3)
and B(D+ -> e+ nu) < 8.8x10^(-6).Comment: 24 pages, 11 figures and 6 tables, v2 replaced some figure vertical
axis scales, v3 corrections from PRD revie
Incidence and characteristics of distal radius fractures in a southern Swedish region
<p>Abstract</p> <p>Background</p> <p>The incidence of distal radius fracture has increased substantially during the last 50 years according to several studies that estimated the overall incidence in various general populations. The incidence of fracture classified according to severity has not been well documented. The aim of this population-based study was to estimate the overall and type-specific incidence rates of distal radius fracture in a representative population in southern Sweden.</p> <p>Methods</p> <p>During 2001, all persons older than 18 years with acute distal radius fracture in the southern Swedish region of Northeastern Scania were prospectively recorded. A radiologist classified the fractures according to the AO system and measured volar tilt and ulnar variance. A fracture with volar tilt outside a range of -5° to 20° and/or ulnar variance of 2 mm or greater was defined as displaced.</p> <p>Results</p> <p>335 persons with acute distal radius fracture were recorded during the 1-year period. The overall incidence rate was 26 (95% confidence interval 23–29) per 10,000 person-years. Among women the incidence rate increased rapidly from the age of 50 and reached a peak of 119 per 10,000 person-years in women 80 years and older. The incidence rate among women 50 to 79 years old (56 per 10,000 person-years) was lower than that reported in previous studies of similar populations. Among men the incidence rate was low until the age of 80 years and older when it increased to 28 per 10,000 person-years. Fractures classified as AO type A comprised about 80% of the fractures in women and 64% in men. Almost two-thirds of all fractures were displaced and among men and women 80 years and older more than 80% of the fractures were displaced.</p> <p>Conclusion</p> <p>The incidence rate of distal radius fracture in women 50 to 79 years old was lower than previously reported, which may indicate declining incidence in this group. In both sexes, the incidence was highest in the age group of 80 years and older. With a growing number of elderly in the general population, the impact of distal radius fracture in the future may be considerable.</p
J/psi and psi(2S) Radiative Transitions to eta_c
Using 24.5 million psi(2S) decays collected with the CLEO-c detector at CESR
we present the most precise measurements of magnetic dipole transitions in the
charmonium system. We measure B(psi(2S)->gamma eta_c) =
(4.32+/-0.16+/-0.60)x10^-3, B(J/psi->gamma eta_c)/B(psi(2S)->gamma eta_c) =
4.59+/-0.23+/-0.64, and B(J/psi->gamma eta_c) = (1.98+/-0.09+/-0.30)%. We
observe a distortion in the eta_c line shape due to the photon-energy
dependence of the magnetic dipole transition rate. We find that measurements of
the eta_c mass are sensitive to the line shape, suggesting an explanation for
the discrepancy between measurements of the eta_c mass in radiative transitions
and other production mechanisms.Comment: 11 pages, 3 figure
Inclusive chi_bJ(nP) Decays to D0 X
Using Upsilon(2S) and Upsilon(3S) data collected with the CLEO III detector
we have searched for decays of chi_bJ to final states with open charm. We fully
reconstruct D0 mesons with p_D0 > 2.5 GeV/c in three decay modes (K-pi+,
K-pi+pi0, and K-pi-pi+pi+) in coincidence with radiative transition photons
that tag the production of one of the chi_bJ(nP) states. We obtain significant
signals for the two J=1 states. Recent NRQCD calculations of chi_{bJ}(nP) --> c
cbar X depend on one non-perturbative parameter per chi_bJ triplet. The
extrapolation from the observed D0 X rate over a limited momentum range to a
full c cbar X rate also depends on these same parameters. Using our data to fit
for these parameters, we extract results which agree well with NRQCD
predictions, confirming the expectation that charm production is largest for
the J=1 states. In particular, for J=1, our results are consistent with c cbar
g accounting for about one-quarter of all hadronic decays.Comment: Version 2 updates include corrections to important errors in Table V
and VII column headers which summarize results, and additional minor edits.
17 pages, available through http://www.lns.cornell.edu/public/CLNS
Measurement of the Absolute Branching Fraction of D_s^+ --> tau^+ nu_tau Decay
Using a sample of tagged D_s decays collected near the D^*_s D_s peak
production energy in e+e- collisions with the CLEO-c detector, we study the
leptonic decay D^+_s to tau^+ nu_tau via the decay channel tau^+ to e^+ nu_e
bar{nu}_tau. We measure B(D^+_s to tau^+ nu_tau) = (6.17 +- 0.71 +- 0.34) %,
where the first error is statistical and the second systematic. Combining this
result with our measurements of D^+_s to mu^+ nu_mu and D^+_s to tau^+ nu_tau
(via tau^+ to pi^+ bar{nu}_tau), we determine f_{D_s} = (274 +- 10 +- 5) MeV.Comment: 9 pages, postscript also available through
http://www.lns.cornell.edu/public/CLNS/2007/, revise
MICE: The muon ionization cooling experiment. Step I: First measurement of emittance with particle physics detectors
Copyright @ 2011 APSThe Muon Ionization Cooling Experiment (MICE) is a strategic R&D project intended to demonstrate the only practical solution to providing high brilliance beams necessary for a neutrino factory or muon collider. MICE is under development at the Rutherford Appleton Laboratory (RAL) in the United Kingdom. It comprises a dedicated beamline to generate a range of input muon emittances and momenta, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. The emittance of the incoming beam will be measured in the upstream magnetic spectrometer with a scintillating fiber tracker. A cooling cell will then follow, alternating energy loss in Liquid Hydrogen (LH2) absorbers to RF cavity acceleration. A second spectrometer, identical to the first, and a second muon identification system will measure the outgoing emittance. In the 2010 run at RAL the muon beamline and most detectors were fully commissioned and a first measurement of the emittance of the muon beam with particle physics (time-of-flight) detectors was performed. The analysis of these data was recently completed and is discussed in this paper. Future steps for MICE, where beam emittance and emittance reduction (cooling) are to be measured with greater accuracy, are also presented.This work was supported by NSF grant PHY-0842798
Contralateral hip fractures and other osteoporosis-related fractures in hip fracture patients: Incidence and risk factors. An observational cohort study of 1,229 patients
Purpose: To report risk factors, 1-year and overall risk for a contralateral hip and other osteoporosis-related fractures in a hip fracture population. Methods: An observational study on 1,229 consecutive patients of 50 years and older, who sustained a hip fracture between January 2005 and June 2009. Fractures were scored retrospectively for 2005-2008 and prospectively for 2008-2009. Rates of a contralateral hip and other osteoporosis- related fractures were compared between patients with and without a history of a fracture. Previous fractures, gender, age and ASA classification were analysed as possible risk factors. Results: The absolute risk for a contralateral hip fracture was 13.8 %, for one or more osteoporosis-related fracture( s) 28.6 %. First-, second- and third-year risk for a second hip fracture was 2, 1 and 0 %. Median (IQR) interval between both hip fractures was 18.5 (26.6) months. One-year incidence of other fractures was 6 %. Only age was a risk factor for a contralateral hip fracture, hazard ratio (HR) 1.02 (1.006-1.042, p = 0.008). Patients with a history of a fracture (33.1 %) did not have a higher incidence of fractures during follow-up (16.7 %) than patients without fractures in their history (14 %). HR for a contralateral hip fracture for the fracture versus the non-fracture group was 1.29 (0.75-2.23, p = 0.360). Conclusion: The absolute risk of a contralateral hip fracture after a hip fracture is 13.8 %, the 1-year risk was 2 %, with a short interval between the 2 hip fractures. Age was a risk factor for sustaining a contralateral hip fracture; a fracture in history was not
Observation of an Exotic Baryon in Exclusive Photoproduction from the Deuteron
In an exclusive measurement of the reaction , a
narrow peak that can be attributed to an exotic baryon with strangeness
is seen in the invariant mass spectrum. The peak is at
GeV/c with a measured width of 0.021 GeV/c FWHM, which is largely
determined by experimental mass resolution. The statistical significance of the
peak is . The mass and width of the observed peak are
consistent with recent reports of a narrow baryon by other experimental
groups.Comment: 5 pages, 5 figure
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