New precision measurements of the 235U(n,γ) cross section.

The neutron capture cross section of (235)U was measured for the neutron incident energy region between 4 eV and 1 MeV at the DANCE facility at the Los Alamos Neutron Science Center with an unprecedented accuracy of 2-3% at 1 keV. The new methodology combined three independent measurements. In the main experiment, a thick actinide sample was used to determine neutron capture and neutron-induced fission rates simultaneously. In the second measurement, a fission tagging detector was used with a thin actinide sample and detailed characteristics of the prompt-fission gamma rays were obtained. In the third measurement, the neutron scattering background was characterized using a sample of (208)Pb. The relative capture cross section was obtained from the experiment with the thick (235)U sample using a ratio method after the subtraction of the fission and neutron scattering backgrounds. Our result indicates errors that are as large as 30% in the 0.5-2.5 keV region, in the current knowledge of neutron capture as embodied in major nuclear data evaluations. Future modifications of these databases using the improved precision data given herein will have significant impacts in neutronics calculations for a variety of nuclear technologies.

Predictors of Internalizing Behaviors in Ukrainian Children.

OBJECTIVE: To (a) estimate the level of child internalizing problems in a sample of Ukrainian school-age children and (b) examine the relationships between child internalizing psychopathology and parenting practices, depression, alcohol use, and sociodemographics. BACKGROUND: Most research on child internalizing behaviors has used samples from high-income countries, but there is a lack of information about children's behaviors and associated risk and protective factors from low- and middle-income countries such as Ukraine. An ecological-transactional model framework was used in this study to examine maternal and family-level factors associated with child internalizing behavior problems. METHOD: Data were gathered from a community-based sample of Ukrainian mothers and children between 9 and 16 years of age (n = 251) using face-to-face interviews. Multiple linear regression analysis was used to examine the relationship among the independent variables (e.g., alcohol use, depression, and parenting behaviors) and children's internalizing behaviors. RESULTS: Older children, especially boys, reported fewer internalizing problems. Increased internalizing symptomatology was associated with mothers' older age, higher level of depression, lower use of positive parenting, and poor child monitoring and supervision. CONCLUSION: These results raise awareness about the importance of child familial backgrounds while trying to address child mental health problems in Ukraine. IMPLICATIONS: Family practitioners may want to help mothers learn and apply positive parenting and effective supervision and monitoring skills to help reduce their children's depression and anxiety symptoms. Additionally, helping to decrease maternal depression may have a positive trickle-down effect on their children's internalizing behaviors.

Study of fitting algorithms applied to simultaneous analysis of large numbers of peaks in gamma-ray spectra.

In this paper several nonlinear fitting algorithms without matrix inversion are proposed and investigated. The fitting algorithms represent an integral part of the analysis procedure, allowing us to simultaneously process large numbers of peaks in large blocks of data. The algorithms were applied to the analysis of both one-dimensional as well as two-fold coincidence gamma-ray spectra. The properties of the proposed methods and the suitability of employing the appropriate algorithms to different kinds of gamma-ray spectra were studied.