316 research outputs found
Planetary radio astronomy observations from Voyager-2 near Saturn
Voyager-2 planetry radio astronomy measurements obtained near Saturn are discussed. They indicate that Saturnian kilometric radiation is emitted by a strong, dayside source at auroral latitudes in the northern hemisphere and by a weaker (by more than an order of magnitude) source at complementary latitudes in the southern hemisphere. These emissions are variable both due to Saturn's rotation and, on longer time scales, probably due to influences of the solar wind and the satellite Dione. The Saturn electrostatic discharge bursts first discovered by Voyager-1 and attributed to emissions from the B-ring were again observed with the same broadband spectral properties and a 10(h)11(m) + or - 5(m) episodic recurrence period but with an occurrence frequency of only of about 30 percent of that detected with Voyager-1. During the crossing of the ring plane at a distance of 2.88 R sub S, an intense noise event is interpreted to be consequence of the impact/vaporization/ionization of charged micron-size G-ring particles distributed over a total vertical thickness of about 1500 km
MARCH WET AVALANCHE PREDICTION AT BRIDGER BOWL SKI AREA, MONTANA
ABSTRACT: Few avalanche forecast models are tailored specifically for wet avalanche forecasting. Bridger Bowl (intermountain climate) is a good area to develop a wet avalanche probability model. The primary archived data consists of eight variables. The archived data for March from 1968 to 2001 (1996 data unavailable) were used to develop 68 predictor variables related to temperature, snowpack settlement, and precipitation. The original dataset was divided into days with snowfall in the past 48 hours (new snow) and days without (old snow). There were 33 significant old snow variables and 22 significant new snow variables. Six variables are common to both old and new snow. The best predictor variables for old and new snow are different. The variables were analyzed with binomial logistic regression to produce probability models for old snow and for new snow wet avalanche conditions. The old snow model uses the prediction day minimum temperature and the two-day change in total snow depth as predictor variables and has a 89% overall success rate. However, the majority of this success is due to correct prediction of days without wet avalanches (96% of all correct predictions). The new snow model uses the prediction day minimum temperature and three-day cumulative new snow water equivalent as predictor variables, but is less useful. The models are applicable only to Bridger Bowl. The numerical forecast models can be used as one of the tools in the forecasting toolbox but limited data and complexity of process require that the decisions about closure remain in the hands of the ski patrol
MARCH WET AVALANCHE PREDICTION AT BRIDGER BOWL SKI AREA, MONTANA
ABSTRACT: Few avalanche forecast models are tailored specifically for wet avalanche forecasting. Bridger Bowl (intermountain climate) is a good area to develop a wet avalanche probability model. The primary archived data consists of eight variables. The archived data for March from 1968 to 2001 (1996 data unavailable) were used to develop 68 predictor variables related to temperature, snowpack settlement, and precipitation. The original dataset was divided into days with snowfall in the past 48 hours (new snow) and days without (old snow). There were 33 significant old snow variables and 22 significant new snow variables. Six variables are common to both old and new snow. The best predictor variables for old and new snow are different. The variables were analyzed with binomial logistic regression to produce probability models for old snow and for new snow wet avalanche conditions. The old snow model uses the prediction day minimum temperature and the two-day change in total snow depth as predictor variables and has a 89% overall success rate. However, the majority of this success is due to correct prediction of days without wet avalanches (96% of all correct predictions). The new snow model uses the prediction day minimum temperature and three-day cumulative new snow water equivalent as predictor variables, but is less useful. The models are applicable only to Bridger Bowl. The numerical forecast models can be used as one of the tools in the forecasting toolbox but limited data and complexity of process require that the decisions about closure remain in the hands of the ski patrol
The electric dipole response of Se above 4 MeV
The dipole response of Se in the energy range 4 to 9 MeV has been
analyzed using a polarized photon scattering
technique, performed at the High Intensity -Ray Source facility, to
complement previous work performed using unpolarized photons. The results of
this work offer both an enhanced sensitivity scan of the dipole response and an
unambiguous determination of the parities of the observed J=1 states. The
dipole response is found to be dominated by excitations, and can
reasonably be attributed to a pygmy dipole resonance. Evidence is presented to
suggest that a significant amount of directly unobserved excitation strength is
present in the region, due to unobserved branching transitions in the decays of
resonantly excited states. The dipole response of the region is underestimated
when considering only ground state decay branches. We investigate the electric
dipole response theoretically, performing calculations in a 3D cartesian-basis
time-dependent Skyrme-Hartree-Fock framework.Comment: 20 pages, 18 figures, to be submitted to PR
European Echinococcosis Registry: Human Alveolar Echinococcosis, Europe, 1982–2000
Surveillance for alveolar echinococcosis in central Europe was initiated in 1998. On a voluntary basis, 559 patients were reported to the registry. Most cases originated from rural communities in regions from eastern France to western Austria; single cases were reported far away from the disease-“endemic” zone throughout central Europe. Of 210 patients, 61.4% were involved in vocational or part-time farming, gardening, forestry, or hunting. Patients were diagnosed at a mean age of 52.5 years; 78% had symptoms. Alveolar echinococcosis primarily manifested as a liver disease. Of the 559 patients, 190 (34%) were already affected by spread of the parasitic larval tissue. Of 408 (73%) patients alive in 2000, 4.9% were cured. The increasing prevalence of Echinococcus multilocularis in foxes in rural and urban areas of central Europe and the occurrence of cases outside the alveolar echinococcosis–endemic regions suggest that this disease deserves increased attention
Post-treatment follow-up study of abdominal cystic echinococcosis in Tibetan communities of northwest Sichuan Province, China
Background: Human cystic echinococcosis (CE), caused by the larval stage of Echinococcus granulosus, with the liver as the
most frequently affected organ, is known to be highly endemic in Tibetan communities of northwest Sichuan Province.
Antiparasitic treatment with albendazole remains the primary choice for the great majority of patients in this resource-poor
remote area, though surgery is the most common approach for CE therapy that has the potential to remove cysts and lead
to complete cure. The current prospective study aimed to assess the effectiveness of community based use of cyclic
albendazole treatment in Tibetan CE cases, and concurrently monitor the changes of serum specific antibody levels during
treatment.
Methodology/Principal Findings: Ultrasonography was applied for diagnosis and follow-up of CE cases after cyclic
albendazole treatment in Tibetan communities of Sichuan Province during 2006 to 2008, and serum specific IgG antibody
levels against Echinococcus granulosus recombinant antigen B in ELISA was concurrently monitored in these cases. A total of
196 CE cases were identified by ultrasound, of which 37 (18.9%) showed evidence of spontaneous healing/involution of
hepatic cyst(s) with CE4 or CE5 presentations. Of 49 enrolled CE cases for treatment follow-up, 32.7% (16) were considered
to be cured based on B-ultrasound after 6 months to 30 months regular albendazole treatment, 49.0% (24) were improved,
14.3% (7) remained unchanged, and 4.1% (2) became aggravated. In general, patients with CE2 type cysts (daughter cysts
present) needed a longer treatment course for cure (26.4 months), compared to cases with CE1 (univesicular cysts) (20.4
months) or CE3 type (detached cyst membrane or partial degeneration of daughter cysts) (9 months). In addition, the
curative duration was longer in patients with large (.10 cm) cysts (22.3 months), compared to cases with medium (5–
10 cm) cysts (17.3 months) or patients with small (,5 cm) cysts (6 months). At diagnosis, seven (53.8%) of 13 cases with CE1
type cysts without any previous intervention showed negative specific IgG antibody response to E. granulosus recombinant
antigen B (rAgB). However, following 3 months to 18 months albendazole therapy, six of these 7 initially seronegative CE1
cases sero-converted to be specific IgG antibody positive, and concurrently ultrasound scan showed that cysts changed to
CE3a from CE1 type in all the six CE cases. Two major profiles of serum specific IgG antibody dynamics during albendazole
treatment were apparent in CE cases: (i) presenting as initial elevation followed by subsequent decline, or (ii) a persistent
decline. Despite a decline, however, specific antibody levels remained positive in most improved or cured CE cases.
Conclusions: This was the first attempt to follow up community-screened cystic echinococcosis patients after albendazole
therapy using ultrasonography and serology in an endemic Tibetan region. Cyclic albendazole treatment proved to be
effective in the great majority of CE cases in this resource-poor area, but periodic abdominal ultrasound examination was
necessary to guide appropriate treatment. Oral albendazole for over 18 months was more likely to result in CE cure. Poor
drug compliance resulted in less good outcomes. Serology with recombinant antigen B could provide additional limited
information about the effectiveness of albendazole in CE cases. Post-treatment positive specific IgG antibody
seroconversion, in initially seronegative, CE1 patients was considered a good indication for positive therapeutic efficacy
of albendazole
Dipole Strength Distributions from HIGS Experiments
A series of photon scattering experiments has been performed on the double-beta decay partners 76Ge and 76Se, in order to investigate their dipole response up to the neutron separation threshold. Gamma-ray beams from bremsstrahlung at the S-DALINAC and from Compton-backscattering at HIGS have been used to measure absolute cross sections and parities of dipole excited states, respectively. The HIGS data allows for indirect measurement of averaged branching ratios, which leads to significant corrections in the observed excitation cross sections. Results are compared to statistical calculations, to test photon strength functions and the Axel-Brink hypothesi
The high-efficiency {\gamma}-ray spectroscopy setup {\gamma}3 at HI{\gamma}S
The existing Nuclear Resonance Fluorescence (NRF) setup at the HI{\gamma}S
facility at the Triangle Universities Nuclear Laboratory at Duke University has
been extended in order to perform {\gamma}-{\gamma} coincidence experiments.
The new setup combines large volume LaBr3:Ce detectors and high resolution HPGe
detectors in a very close geometry to offer high efficiency, high energy
resolution as well as high count rate capabilities at the same time. The
combination of a highly efficient {\gamma}-ray spectroscopy setup with the
mono-energetic high-intensity photon beam of HI{\gamma}S provides a worldwide
unique experimental facility to investigate the {\gamma}-decay pattern of
dipole excitations in atomic nuclei. The performance of the new setup has been
assessed by studying the nucleus \sulfur at 8.125 MeV beam energy. The
{\gamma}-decay branching ratio from the level at 8125.4 keV to the first
excited state was determined to 15.7(3)%.Comment: 9 pages, 11 figure
Ultrasonographically detected gallbladder polyps: A reason for concern? A seven-year follow-up study
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