938 research outputs found
Angular Correlations in Internal Pair Conversion of Aligned Heavy Nuclei
We calculate the spatial correlation of electrons and positrons emitted by
internal pair conversion of Coulomb excited nuclei in heavy ion collisions. The
alignment or polarization of the nucleus results in an anisotropic emission of
the electron-positron pairs which is closely related to the anisotropic
emission of -rays. However, the angular correlation in the case of
internal pair conversion exhibits diverse patterns. This might be relevant when
investigating atomic processes in heavy-ion collisions performed at the Coulomb
barrier.Comment: 27 pages + 6 eps figures, uses revtex.sty and epsf.sty,
tar-compressed and uuencoded with uufile
217 MECHANISMS OF ACTION OF ESE1, A NOVEL TRANSCRIPTIONAL REGULATOR OF CARTILAGE REMODELING, IN MMP-13 REGULATION
Ischemic preconditioning (IPC) limits myocardial infarct size through the activation of the PI3K-Akt signal cascade; however, little is known about the roles of individual PI3K isoforms in cardioprotection. We aimed, therefore, to elucidate the role of the PI3K alpha isoform in cardioprotection Pharmacological PI3K alpha inhibition was assessed in isolated-perfused mouse hearts subjected to ischemia/reperfusion injury (IRI), either during the IPC procedure or at reperfusion. PI3K alpha inhibition abrogated the IPC-induced protective effect at reperfusion, but not when given only during the IPC protocol. These results were confirmed in an in vivo model. Moreover, pharmacological PI3K alpha activation by insulin at reperfusion was sufficient to confer cardioprotection against IRI. In addition, PI3K alpha was shown to be expressed and activated in mouse cardiomyocytes, mouse cardiac endothelial cells, as well as in mouse and human heart tissue. Furthermore, PI3K alpha was shown to mediate its effect though the inhibition of mitochondrial permeability transition pore opening. In conclusion, PI3K alpha activity is required during the early reperfusion phase to reduce myocardial infarct size. This suggests that strategies specifically enhancing the alpha isoform of PI3K at reperfusion promote tissue salvage and as such, and could provide a direct target for clinical treatment of IRI.Fundacion Rafael del Pino
FONDECYT
3160298
British Heart Foundation
Cancer Research UK
C23338/A15965
UK NIHR University College London Hospitals Biomedical Research Centr
Shell structure underlying the evolution of quadrupole collectivity in S-38 and S-40 probed by transient-field g-factor measurements on fast radioactive beams
The shell structure underlying shape changes in neutron-rich nuclei between
N=20 and N=28 has been investigated by a novel application of the transient
field technique to measure the first-excited state g factors in S-38 and S-40
produced as fast radioactive beams. Details of the new methodology are
presented. In both S-38 and S-40 there is a fine balance between the proton and
neutron contributions to the magnetic moments. Shell model calculations which
describe the level schemes and quadrupole properties of these nuclei also give
a satisfactory explanation of the g factors. In S-38 the g factor is extremely
sensitive to the occupation of the neutron p3/2 orbit above the N=28 shell gap
as occupation of this orbit strongly affects the proton configuration. The g
factor of deformed S-40 does not resemble that of a conventional collective
nucleus because spin contributions are more important than usual.Comment: 10 pages, 36 figures, accepted for publication in Physical Review
Solar Fusion Cross Sections
We review and analyze the available information for nuclear fusion cross
sections that are most important for solar energy generation and solar neutrino
production. We provide best values for the low-energy cross-section factors
and, wherever possible, estimates of the uncertainties. We also describe the
most important experiments and calculations that are required in order to
improve our knowledge of solar fusion rates.Comment: LaTeX file, 48 pages (figures not included). To appear in Rev. Mod.
Phys., 10/98. All authors now listed. Full postscript version with figures
available at http://www.sns.ias.edu/~jnb/Papers/Preprints/nuclearfusion.htm
A multi-detector array for high energy nuclear e+e- pair spectrosocopy
A multi-detector array has been constructed for the simultaneous measurement
of energy- and angular correlation of electron-positron pairs produced in
internal pair conversion (IPC) of nuclear transitions up to 18 MeV. The
response functions of the individual detectors have been measured with
mono-energetic beams of electrons. Experimental results obtained with 1.6 MeV
protons on targets containing B and F show clear IPC over a wide
angular range. A comparison with GEANT simulations demonstrates that angular
correlations of pairs of transitions in the energy range between 6 and
18 MeV can be determined with sufficient resolution and efficiency to search
for deviations from IPC due to the creation and subsequent decay into
of a hypothetical short-lived neutral boson.Comment: 20 pages, 8 figure
Prenatal Vitamin D Supplementation and Child Respiratory Health: A Randomised Controlled Trial
PMCID: PMC3691177This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Nano-analyses of wear particles from metal-on-metal and non-metal-on-metal dual modular neck hip arthroplasty
Increased failure rates due to metallic wear particle-associated adverse local tissue reactions (ALTR) is a significant clinical problem in resurfacing and total hip arthroplasty. Retrieved periprosthetic tissue of 53 cases with corrosion/conventional metallic wear particles from 285 revision operations for ALTR was selected for nano-analyses. Three major classes of hip implants associated with ALTR, metal-on-metal hip resurfacing arthroplasty (MoM HRA) and large head total hip replacement (MoM LHTHA) and non-metal-on-metal dual modular neck total hip replacement (Non-MoM DMNTHA) were included. The size, shape, distribution, element composition, and crystal structure of the metal particles were analyzed by conventional histological examination and electron microscopy with analytic tools of 2D X-ray energy dispersive spectrometry and X-ray diffraction. Distinct differences in size, shape, and element composition of the metallic particles were detected in each implant class which correlate with the histological features of severity of ALTR and variability in implant performance
Early changes in bone mineral density measured by digital X-ray radiogrammetry predict up to 20 years radiological outcome in rheumatoid arthritis
ABSTRACT: INTRODUCTION: Change in bone mineral density (BMD) in the hand, as evaluated by digital X-ray radiogrammetry (DXR) of the II-IV metacarpal bones, has been suggested to predict future joint damage in rheumatoid arthritis (RA). This study's objective was to investigate if DXR-BMD loss early in the disease predicts development of joint damage in RA patients followed for up to 20 years. METHODS: 183 patients (115 women and 68 men) with early RA (mean disease duration 11 months) included from 1985 to 1989 were followed prospectively (the Lund early RA cohort). Clinical and functional measures were assessed yearly. Joint damage was evaluated according to the Larsen score on radiographs of hands and feet taken in years 0 to 5, 10, 15 and 20. These radiographs were digitized and BMD of the II-IV metacarpal bones was evaluated by DXR (Sectra, Linkoping. Sweden). Early DXR-BMD change rate (bone loss) per year calculated from the first 2 radiographs taken on average 9 months apart (SD 4.8) were available for 135 patients. Mean values of right and left hand were used. RESULTS: Mean early DXR-BMD loss during the first year calculated was -0.023 g/cm2 (SD 0.025). Patients with marked bone loss, i.e. early DXR-BMD loss above the median for the group, had significantly worse progression of joint damage at all examinations during the 20-year period. CONCLUSIONS: Early DXR-BMD progression rate predicted development of joint damage evaluated according to Larsen at year one and further onwards up to 20 years in this cohort of early RA patients
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