RESUMO
Reactor neutrino experiments have seen major improvements in precision in recent years. With the experimental uncertainties becoming lower than those from theory, carefully considering all sources of ν ¯ e is important when making theoretical predictions. One source of ν ¯ e that is often neglected arises from the irradiation of the nonfuel materials in reactors. The ν ¯ e rates and energies from these sources vary widely based on the reactor type, configuration, and sampling stage during the reactor cycle and have to be carefully considered for each experiment independently. In this article, we present a formalism for selecting the possible ν ¯ e sources arising from the neutron captures on reactor and target materials. We apply this formalism to the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, the ν ¯ e source for the the Precision Reactor Oscillation and Spectrum Measurement (PROSPECT) experiment. Overall, we observe that the nonfuel ν ¯ e contributions from HFIR to PROSPECT amount to 1% above the inverse beta decay threshold with a maximum contribution of 9% in the 1.8-2.0 MeV range. Nonfuel contributions can be particularly high for research reactors like HFIR because of the choice of structural and reflector material in addition to the intentional irradiation of target material for isotope production. We show that typical commercial pressurized water reactors fueled with low-enriched uranium will have significantly smaller nonfuel ν ¯ e contribution.
RESUMO
Non-insulin-dependent diabetes mellitus (NIDDM) is a chronic disabling disease, that shortens length of life and implies a high burden for a community. Its prevalence goes from 0 per cent in Papua, New Guinea to 34 per cent in Pima Indians. There are very few prevalence studies in Mexico, and the strength of association of the known risk factors with the occurrence of the disease is not established. A prevalence cross sectional study was carried out with users of a first level medical care unit, with a meter measure of capillary glucose levels. Those with a previous diagnosis of diabetes or whose capillary glucose level were 200 mg or over were considered diabetics. Hyperglycemia was when the levels were recorded between 121 and 199 mg. The crude prevalence of NIDDM was 5.6 per cent (CI 95% 4.5-6.8), With almost no sex difference. Hyperglycemia prevalence was 2.9 per cent (CI 95% 2.0-3.7). Age was the main risk factor for the development of NIDDM. Those between 40 and 59 years showed a high risk (OR 10.8; CI 95% 5.4-22.0; p < 0.0001), and it was greater for the 60 years or elder (OR 20.6; CI 95% 9.8-44.1; p < 0.0001). Weight was also an important risk factor, with a 2.7 fold greater risk for obese persons (CI 95% 1.6-4.6; p < 0.0001). Other, risk factors were familiar history of diabetes (OR 1.5; CI 95% 0.9-2.3; p = 0.096), and overcrowding (OR 1.9; CI 95% 1.0-3.4; p = 0.03). In order to analyze independently each variable, a logistic regression model was applied, and a similar strength of association was observed for the crude model, but for obesity whose effect was modified by age. When only new cases were analyzed in the former model, the association with obesity was maintained. There is a need to develop prevalence studies of NIDDM in Mexico and to measure the strength of association with the known and the not jet well known risk factors of this disease in order to establish health policies according to the Mexican reality.
