Precise angular distributions have been measured for the first time for the photoproduction of π0 mesons off neutrons bound in the deuteron. The effects from nuclear Fermi motion have been eliminated ...by a complete kinematic reconstruction of the final state. The influence of final-state-interaction effects has been estimated by a comparison of the reaction cross section for quasifree protons bound in the deuteron to the results for free protons and then applied as a correction to the quasifree neutron data. The experiment was performed at the tagged photon facility of the Mainz Microtron MAMI with the Crystal Ball and TAPS detector setup for incident photon energies between 0.45 and 1.4 GeV. The results are compared to the predictions from reaction models and partial-wave analyses based on data from other isospin channels. The model predictions show large discrepancies among each other and the present data will provide much tighter constraints. This is demonstrated by the results of a new analysis in the framework of the Bonn-Gatchina coupled-channel analysis which included the present data.
An observational dataset from a wintertime field campaign in the Inn Valley, Austria, is analysed in order to study mechanisms of air pollution transport in an Alpine valley. The results illustrate ...three types of mechanisms: transport by a density current, back-and-forth transport by valley winds, and transport by slope winds. The first type is associated with an air mass difference along the valley. Cooler air located in the lower part of the valley behaves like a density current and produces the advection of pollutants by upvalley winds. In the second type, strong horizontal gradients in pollution concentrations exist close to ground. Multiple wind reversals result in a back-and-forth transport of pollutants by weak valley winds. In the third type, upslope winds during daytime decrease low-level pollution concentrations and cause the formation of elevated pollution layers.
We consider some theoretical aspects concerning extraction of the
η
d
scattering length from the reaction
γ
d
→
π
0
η
d
. The major source of uncertainty is associated with the mechanism, in which ...the
η
d
state is produced in the
N
(
1535
)
N
→
η
d
transition, and, to a lesser extent, with the energy dependence of the off-shell contribution to the
η
d
interaction.
A diode-pumped, single-frequency laser system emitting at 935 nm has recently been developed to serve as the transmitter for water vapor differential absorption lidar (DIAL) measurements. This laser ...uses Nd:YGG (Y
3
Ga
5
O
12
) as the active medium and emits radiation directly at 935 nm without the need of additional frequency conversion processes. The system was diode-pumped at 806 nm and was built up in a master-oscillator-power-amplifier configuration. It generates more than 30 mJ of pulse energy at 100 Hz repetition rate with a beam quality (
M
2
) of better than 1.4. Since water vapor DIAL demands for stringent requirements of the spectral properties those were carefully investigated in the scope of this paper. Single-frequency operation is achieved by injection seeding and active length control of the oscillator cavity. The range of continuously tunable single-frequency radiation extends to ∼0.4 nm centered around 935.31 nm. Values of the spectral purity of >99.996% were determined using long-pass absorption measurements in the atmosphere exceeding the requirements by a large margin. Finally, for the first time water vapor DIAL measurements were performed using a Nd:YGG laser. The reported results show much promise of these directly pumped lasers at 935 nm for future spaceborne but also airborne water vapor lidar systems.
In this paper, we present new experimental results for the tensor analyzing power
of the reaction
in the region of low proton energies. The results are presented in the photon energy range of
and the ...proton energy range of
. The paper uses the experimental statistics accumulated at the VEPP-3 accelerator complex in 2013. To identify the events of the reaction
, we used the registration of the proton and two
-quanta from the decay
in coincidence. The experimental results were compared with the results of statistical simulation. To perform the statistical simulation, we used the unitary isobar model MAID 2007 for the elementary pion-nucleon photoproduction amplitude and took into account
and
rescattering in the final state of the reaction
.
This report describes a cross-sectional survey of the prevalence of antibodies to hepatitis C virus (anti-HCV) in a rural Egyptian community in the Nile Delta. One half of the village households were ...systematically selected and examined by questionnaire and testing sera for anti-HCV and HCV RNA. Blood samples were obtained from 3,888 (75.4%) of 5,156 residents ≥5 years of age; an additional 111 samples were obtained from children younger than 5 years. Overall, 973 (24.3%) of 3,999 residents were anti-HCV–positive, and the age- and gender-adjusted seroprevalence was 23.7%. Anti-HCV prevalence increased sharply with age, from 9.3% in those 20 years of age and younger to >50% in those older than 35 years. Currently or previously married individuals were more likely to be seropositive than those never married, controlling for age (Mantel-Haenszel risk ratio = 1.8; 95% CI: 1.3, 2.6). Of the 905 anti-HCV–positive samples tested, 65% were also positive for HCV RNA. Active schistosomal infection was not associated with anti-HCV status; however, history of antischistosomal injection therapy (reported by 19% of anti-HCV positives) was a risk for anti-HCV (age-adjusted risk ratio = 1.3; 95% CI: 1.2, 1.5). This study, the largest community-based survey to date, supports earlier reports of high levels of anti-HCV among adults in rural areas of Egypt, although many of those who are seropositive will not have active liver disease. The large reservoir of HCV infection in the community provides an opportunity to investigate risk factors for transmission, the natural history of infection and effectiveness of preventive methodologies, and raises concern about the prospect of an increasing incidence of chronic liver disease in the coming decades.
(Hepatology 2000;32:111-115.)
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