856 research outputs found
Nuclear Propelled Vessels and Neutrino Oscillation Experiments
We study the effect of naval nuclear reactors on the study of neutrino
oscillations. We find that the presence of naval reactors at unknown locations
and times may limit the accuracy of future very long baseline reactor-based
neutrino oscillation experiments. At the same time we argue that a nuclear
powered surface ship such as a large Russian ice-breaker may provide an ideal
source for precision experiments. While the relatively low reactor power would
in this case require a larger detector, the source could be conveniently
located at essentially any distance from a detector built at an underground
location near a shore in a region of the world far away from other nuclear
installations. The variable baseline would allow for a precise measurement of
backgrounds and greatly reduced systematics from reactor flux and detector
efficiency. In addition, once the oscillation measurement is completed, the
detector could perform geological neutrino and astrophysical measurements with
minimal reactor background.Comment: 4 pages, 2 figure
Aircraft measurements of trace gases and particles near the tropopause
Research activities which were performed using atmospheric constituent data obtained by the NASA Global Atmospheric Sampling Program are described. The characteristics of the particle size spectrum in various meteorological settings from a special collection of GASP data are surveyed. The relationship between humidity and cloud particles is analyzed. Climatological and case studies of tropical ozone distributions measured on a large number of flights are reported. Particle counter calibrations are discussed as well as the comparison of GASP particle data in the upper troposphere with other measurements at lower altitudes over the Pacific Ocean
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Simulating Injectate/Rock Chemical Interaction In Fractured Desert Peak Quartz Monzonite
Simulations of the interactions of injected fluids with minerals within an engineered fracture in a sample of Desert Peak quartz monzonite were compared with experimental observations of fluid chemistry and fracture permeability. The observed decrease in permeability and effective hydraulic aperture was much more rapid ({approx}1.0 {micro}m/day) for a core injected with a mixed salt solution containing dissolved silica (near-saturation injectate), compared to cores injected with NaCl (far-from-saturation injectate) ({approx}0.1 {micro}m/day). Simulations were in qualitative agreement with these observations. Near-saturation injectate is predicted to result in net precipitation of secondary phases in the fracture ({approx}0.12 {micro}m/day), compared to a net dissolution of the rock for the far-from-saturation injectate ({approx}0.3 {micro}m/day). Permeability loss for the near-saturation-injectate is ascribed to precipitation in the fracture as well as potential dissolution of primary mineral asperities. Permeability loss for the far-from-saturation fluid is ascribed to dissolution of asperities and smoothing of the fracture. Post-test analysis of the fracture surface will be necessary to verify the processes occurring. The simplified geochemical models used do not account for mineral heterogeneity or for distributions of fluid residence times which could be important controls on permeability evolution. Further analysis is planned to explicitly account for these phenomena
Measurement of the double-\beta decay half-life of ^{136}Xe with the KamLAND-Zen experiment
We present results from the KamLAND-Zen double-beta decay experiment based on
an exposure of 77.6 days with 129 kg of Xe. The measured two-neutrino
double-beta decay half-life of Xe is yr, consistent with a recent
measurement by EXO-200. We also obtain a lower limit for the neutrinoless
double-beta decay half-life, yr at 90%
confidence level (C.L.), which corresponds to almost a five-fold improvement
over previous limits.Comment: 6 pages, 4 figures. Version as published in PR
KamLAND Sensitivity to Neutrinos from Pre-Supernova Stars
In the late stages of nuclear burning for massive stars (M>8~M_{\sun}), the
production of neutrino-antineutrino pairs through various processes becomes the
dominant stellar cooling mechanism. As the star evolves, the energy of these
neutrinos increases and in the days preceding the supernova a significant
fraction of emitted electron anti-neutrinos exceeds the energy threshold for
inverse beta decay on free hydrogen. This is the golden channel for liquid
scintillator detectors because the coincidence signature allows for significant
reductions in background signals. We find that the kiloton-scale liquid
scintillator detector KamLAND can detect these pre-supernova neutrinos from a
star with a mass of 25~M_{\sun} at a distance less than 690~pc with 3
significance before the supernova. This limit is dependent on the neutrino mass
ordering and background levels. KamLAND takes data continuously and can provide
a supernova alert to the community.Comment: 19 pages, 6 figures, 1 tabl
Study of electron anti-neutrinos associated with gamma-ray bursts using KamLAND
We search for electron anti-neutrinos () from long and
short-duration gamma-ray bursts~(GRBs) using data taken by the KamLAND detector
from August 2002 to June 2013. No statistically significant excess over the
background level is found. We place the tightest upper limits on
fluence from GRBs below 7 MeV and place first constraints on
the relation between luminosity and effective temperature.Comment: 16 pages and 5 figure
Shoulder pain due to cervical radiculopathy: an underestimated long-term complication of herpes zoster virus reactivation?
Purpose
To evaluate if herpes zoster virus (HZV) reactivation may be considered in the aetiology of cervical radiculopathy.
Methods
The study group was composed of 110 patients (52 M-58F;mean age ± SD:46.5 ± 6.12; range:40-73) with a clinical diagnosis of cervical radiculopathy. Patients with signs of chronic damage on neurophysiological studies were submitted to an X-ray and to an MRI of the cervical spine in order to clarify the cause of the cervical radiculopathy and were investigated for a possible reactivation of HZV; HZV reactivation was considered as “recent” or “antique” if it occurs within or after 24 months from the onset of symptoms, respectively. Data were submitted to statistics.
Results
Thirty-eight patients (34,5%,16 M-22F) had a history of HZV reactivation: four (2 M-2F) were “recent” and 34 (14 M-20F) were “antique”. In 68 of 110 participants (61,8%,30 M-38F), pathological signs on X-ray and/or MRI of the cervical spine appeared; in the remaining 42 (38,2%,22 M-20F) X-ray and MRI resulted as negative. Among patients with HZV reactivation, seven (18,4%) had a “positive” X-ray-MRI while in 31 (81,6%) the instrumental exams were considered as negative. The prevalence of “antique” HZV reactivations was statistically greater in the group of patients with no pathological signs on X-ray/MRI of the cervical spine with respect to the group with a pathological instrumental exam (p < 0.01).
Conclusions
It may be useful to investigate the presence of a positive history of HZV reactivation and to consider it as a long-term complication of a cervical root inflammation especially in patients in which X-ray and MRI of the cervical spine did not show pathological findings
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