232 research outputs found
Distribution of solar wind implanted noble gases in lunar samples
The distribution of solar wind implanted noble gases in lunar samples depends on implantation energy, fluence, diffusion, radiation damage and erosion. It is known that at least the lighter rare gases are fractionated after implantation, but the redistribution processes, which mainly drive the losses, are not well understood. Some information about this one can get by looking at the concentration profiles of solar wind implanted He-4 measured by the Gas Ion Probe in single lunar grains. The observed profiles were divided in three groups. These groups are illustrated and briefly discussed
Results of ultra-low level 71ge counting for application in the Gallex-solar neutrino experiment at the Gran Sasso Underground Physics Laboratory
It has been experimentally verified that the Ultra-Low-Level Counting System for the Gallex solar neutrino experiment is capable of measuring the expected solar up silon-flux to plus or minus 12% during two years of operation
Prevalence and Factors Associated with Depression among Patients with Epilepsy at Aga Khan University Teaching Hospital Nairobi
Objective: To determine the prevalence and factors associated with depression in patients with epilepsy at Aga Khan University Hospital; Nairobi.Design: A Cross-Sectional Survey.Setting: Neurology clinic, Aga Khan University Hospital; NairobiSubjects: Eligible patients with epilepsy on follow-up at the neurology clinic were recruited.Intervention: Beck-Depression-Inventory was administered to evaluate presence of depression.Main Outcome Measures: In addition to depression, patients with co-morbid depression were further evaluated for associated factors.Results: Three-hundred-and-twenty-seven patients were evaluated for presence of depression. Fifty-four patients in the study cohort had depression, giving prevalence of depression; based on the Beck-Depression-Inventory as 16.5 %, (95 % CI 12.7-21.0) There was weak association between mild depression and polytherapy (use of two or more antiepileptic drugs), with OR 2.3, 95%CI 0.9-5.8 however, none between polytherapy and moderate or severe depression. No statistically significant association was found between depression and duration of epilepsy or number of seizures per month over last three months.Conclusion: The prevalence of depression in patients with epilepsy at Aga Khan University Hospital, Nairobi was 16.5 %( 95% CI 12.7-21.0) and polytherapy was weakly associated with mild depression. Depression among patients with epilepsy warrants clinical attention especially in patients on polytherapy. The risk of AED polytherapy was two-fold greater (OR 2.3, 95%CI 0.9-5.8) in patients with mild depression compared to patients with epilepsy without depression
Supernova Reverse Shocks and SiC Growth
We present new mechanisms by which the isotopic compositions of X-type grains
of presolar SiC are altered by reverse shocks in Type II supernovae. We address
three epochs of reverse shocks: pressure wave from the H envelope near t =
10s; reverse shock from the presupernova wind near 10s; reverse
shock from the ISM near 10s. Using 1-D hydrodynamics we show that the
first creates a dense shell of Si and C atoms near 10s in which the SiC
surely condenses. The second reverse shock causes precondensed grains to move
rapidly forward through decelerated gas of different isotopic composition,
during which implantation, sputtering and further condensation occur
simultaneously. The third reverse shock causes only further ion implantation
and sputtering, which may affect trace element isotopic compositions. Using a
25M supernova model we propose solutions to the following unsolved
questions: where does SiC condense?; why does SiC condense in preference to
graphite?; why is condensed SiC Si-rich?; why is O richness no obstacle
to SiC condensation?; how many atoms of each isotope are impacted by a grain
that condenses at time t at radial coordinate r? These many
considerations are put forward as a road map for interpreting SiC X grains
found in meteorites and their meaning for supernova physics.Comment: 28 pages, 14 figures, animation for Figure 3 and machine-readable
Table 3 can be found at
http://antares.steelangel.com/~edeneau/supernova/DHC_2003, Submitted to Ap
Reanalysis of the GALLEX solar neutrino flux and source experiments
After the completion of the gallium solar neutrino experiments at the
Laboratori Nazionali del Gran Sasso (GALLEX}: 1991-1997; GNO: 1998-2003) we
have retrospectively updated the GALLEX results with the help of new technical
data that were impossible to acquire for principle reasons before the
completion of the low rate measurement phase (that is, before the end of the
GNO solar runs). Subsequent high rate experiments have allowed the calibration
of absolute internal counter efficiencies and of an advanced pulse shape
analysis for counter background discrimination. The updated overall result for
GALLEX (only) is (73.4 +7.1 -7.3) SNU. This is 5.3% below the old value of
(77.5 + 7.5 -7.8) SNU (PLB 447 (1999) 127-133) with a substantially reduced
error. A similar reduction is obtained from the reanalysis of the 51Cr neutrino
source experiments of 1994/1995.Comment: Accepted by Physics Letters B January 13, 201
Complete results for five years of GNO solar neutrino observations
We report the complete GNO solar neutrino results for the measuring periods
GNO III, GNO II, and GNO I. The result for GNO III (last 15 solar runs) is
[54.3 + 9.9 - 9.3 (stat.)+- 2.3 (syst.)] SNU (1 sigma) or [54.3 + 10.2 - 9.6
(incl. syst.)] SNU (1 sigma) with errors combined. The GNO experiment is now
terminated after altogether 58 solar exposure runs that were performed between
May 20, 1998 and April 9, 2003. The combined result for GNO (I+II+III) is [62.9
+ 5.5 - 5.3 (stat.) +- 2.5 (syst.)] SNU (1 sigma) or [62.9 + 6.0 - 5.9] SNU (1
sigma) with errors combined in quadrature. Overall, gallium based solar
observations at LNGS (first in GALLEX, later in GNO) lasted from May 14, 1991
through April 9, 2003. The joint result from 123 runs in GNO and GALLEX is
[69.3 +- 5.5 (incl. syst.)] SNU (1 sigma). The distribution of the individual
run results is consistent with the hypothesis of a neutrino flux that is
constant in time. Implications from the data in particle- and astrophysics are
reiterated.Comment: 22 pages incl. 9 Figures and 8 Tables. to appear in: Physics Letters
B (accepted April 13, 2005) PACS: 26.65.+t ; 14.60.P
GNO Solar Neutrino Observations: Results for GNOI
We report the first GNO solar neutrino results for the measuring period GNOI,
solar exposure time May 20, 1998 till January 12, 2000. In the present
analysis, counting results for solar runs SR1 - SR19 were used till April 4,
2000. With counting completed for all but the last 3 runs (SR17 - SR19), the
GNO I result is [65.8 +10.2 -9.6 (stat.) +3.4 -3.6 (syst.)]SNU (1sigma) or
[65.8 + 10.7 -10.2 (incl. syst.)]SNU (1sigma) with errors combined. This may be
compared to the result for Gallex(I-IV), which is [77.5 +7.6 -7.8 (incl.
syst.)] SNU (1sigma). A combined result from both GNOI and Gallex(I-IV)
together is [74.1 + 6.7 -6.8 (incl. syst.)] SNU (1sigma).Comment: submitted to Physics Letters B, June 2000. PACS: 26.65. +t ; 14.60
Pq. Corresponding author: [email protected] ; [email protected]
Female bone physiology resilience in 750-300 BP ‘Polynesian Outlier’ community
Remodelling is a fundamental biological process involved in the maintenance of bone physiology and function. We know that a range of health and lifestyle factors can impact this process in living and past societies, but there is a notable gap in bone remodelling data for populations from the Pacific Islands. We conducted the first examination of femoral cortical histology in n = 69 individuals from 750 – 300 BP Taumako in Solomon Islands, a remote ‘Polynesian Outlier’ island in Melanesia. We tested whether bone remodelling indicators differed between age-at-death groups, and biological sex validated using ancient DNA. Bone vascular canal and osteon size, vascular porosity, and localised osteon densities, corrected by femoral robusticity indices were examined. Females had statistically significantly higher vascular porosities when compared to males, but osteon densities and ratios of canal-to-osteon (~10%) did not differ between the sexes. Compared to males, the femora of Taumako females experienced higher frequencies of remodelling events, which mirrors bone health paradigms through the life-course today. However, contrary to modern populations, female femoral bone tissue did not decline with age. This matches findings in other archaeological samples, and is testament to ancient female bone physiology resilience also in the Pacific region.Introduction - The importance of bone remodelling through human life-course - Bone remodelling in archaeological humans Results - Trends in bone remodelling at Taumako Discussion - Sex-specific trends in cortical bone remodelling - Bone remodelling with age at Taumako Limitations and remarks on temporal and spatial data Conslusions Materials and Method
Female bone physiology resilience in a past Polynesian Outlier community
Remodelling is a fundamental biological process involved in the maintenance of bone physiology and function. We know that a range of health and lifestyle factors can impact this process in living and past societies, but there is a notable gap in bone remodelling data for populations from the Pacific Islands. We conducted the first examination of femoral cortical histology in 69 individuals from ca. 440–150 BP Taumako in Solomon Islands, a remote ‘Polynesian Outlier’ island in Melanesia. We tested whether bone remodelling indicators differed between age groups, and biological sex validated using ancient DNA. Bone vascular canal and osteon size, vascular porosity, and localised osteon densities, corrected by femoral robusticity indices were examined. Females had statistically significantly higher vascular porosities when compared to males, but osteon densities and ratios of canal-osteon (~ 8%) did not differ between the sexes. Our results indicate that, compared to males, localised femoral bone tissue of the Taumako females did not drastically decline with age, contrary to what is often observed in modern populations. However, our results match findings in other archaeological samples—a testament to past female bone physiology resilience, also now observed in the Pacific region.Introduction - Bone remodelling through human life‑course. - Bone remodelling in archaeological humans. Results - Femoral vascular porosity and bone remodelling indicators at Taumako. Discussion - Sex and cortical bone histology at Taumako. - The effect of age on bone histology at Taumako. Remarks on temporal and spatial bone histology data Limitations Conclusions Materials and method
The Nylon Scintillator Containment Vessels for the Borexino Solar Neutrino Experiment
Borexino is a solar neutrino experiment designed to observe the 0.86 MeV Be-7
neutrinos emitted in the pp cycle of the sun. Neutrinos will be detected by
their elastic scattering on electrons in 100 tons of liquid scintillator. The
neutrino event rate in the scintillator is expected to be low (~0.35 events per
day per ton), and the signals will be at energies below 1.5 MeV, where
background from natural radioactivity is prominent. Scintillation light
produced by the recoil electrons is observed by an array of 2240
photomultiplier tubes. Because of the intrinsic radioactive contaminants in
these PMTs, the liquid scintillator is shielded from them by a thick barrier of
buffer fluid. A spherical vessel made of thin nylon film contains the
scintillator, separating it from the surrounding buffer. The buffer region
itself is divided into two concentric shells by a second nylon vessel in order
to prevent inward diffusion of radon atoms. The radioactive background
requirements for Borexino are challenging to meet, especially for the
scintillator and these nylon vessels. Besides meeting requirements for low
radioactivity, the nylon vessels must also satisfy requirements for mechanical,
optical, and chemical properties. The present paper describes the research and
development, construction, and installation of the nylon vessels for the
Borexino experiment
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