The behaviour of uranium oxides in low partial pressures of O2 studied using X-ray photoelectron spectroscopy

Non-stoichiometry, induced by exposure to oxygen and vacuum has been investigated for the uranium oxides UO₂, U₄O₉ and U₃O₈ using X-ray photoelectron spectroscopy. Each stoichiometric uranium oxide is shown to display a unique X-ray photoelectron spectrum which can be altered quite dramatically by changes in stoichiometry and explained by a defect cluster model.     

Quantitative estimates of mammary growth during various physiological states: a review

The parenchymal portion of the mammary gland is immature at birth and begins to grow at a faster rate than the whole body shortly before occurrence of puberty. This accelerated or allometric growth rate is maintained for several estrous cycles, then returns to a growth rate equal to general body growth. Allometric growth of the mammary gland returns at conception and continues in most species for a variable period after parturition. Elevated secretion of estradiol and progesterone throughout pregnancy drives the allometric mammary growth during pregnancy. However, mammary growth during lactation in cows is independent of ovarian secretions and prolactin. Mammary cell numbers during lactation eventually decline as milk production decreases. Concurrent pregnancy reduces mammary cell numbers during lactation, but during the dry period concurrent pregnancy markedly increases mammary cell numbers over those in nonpregnant animals. Dry periods that are short reduce the increments in mammary cell numbers, which normally occur during early stages of the next lactation. Because numbers of mammary epithelial cells are a major determinant of milk yield, understanding the mechanisms that stimulate mammary epithelial cell numbers has the potential to lead to new methods for increasing efficiency of milk production.     

Evolutionary learning of dynamic probabilistic models with large time lags

In this paper, we explore the automatic explanation of multivariate time series (MTS) through learning dynamic Bayesian networks (DBNs). We have developed an evolutionary algorithm which exploits certain characteristics of MTS in order to generate good networks as quickly as possible. We compare this algorithm to other standard learning algorithms that have traditionally been used for static Bayesian networks but are adapted for DBNs in this paper. These are extensively tested on both synthetic and real-world MTS for various aspects of efficiency and accuracy. By proposing a simple representation scheme, an efficient learning methodology, and several useful heuristics, we have found that the proposed method is more efficient for learning DBNs from MTS with large time lags, especially in time-demanding situations. © 2001 John Wiley & Sons, Inc.     

Occupational exposure to HIV: considerations for postexposure prophylaxis and prevention

HIV seroconversion as a result of an occupational exposure is a terrifying concern of healthcare workers who deliver care to patients in a variety of health care settings. In this article the most recent CDC guidelines for the management of HIV exposure and postexposure prophylaxis are reviewed. Prevention of bloodborne pathogen exposures, specifically through the selection of safety devices, is recognized as an important issue.     

Adolescents' explanations for political issues: Concordance with their views of self and society.

The relationships between adolescents' explanations for unemployment, poverty, and homelessness and their beliefs about opportunity, reports of family values, and personal aspirations were tested for 434 teenagers (mean age?=?16 years 4 months). Explanations were coded for references to individual causes, societal causes, or both. Higher maternal education and average household income in the adolescent's school district were positively related to the likelihood of attributing all three problems to societal causes. When explaining unemployment, older adolescents noted both causes, and boys mentioned individual factors whereas girls mentioned societal factors. After adjustment for background factors, those endorsing individual causes were more likely to believe that all Americans enjoyed equal opportunity and that government support encouraged dependency, and they were more committed to materialist goals. In contrast, youth endorsing societal or situational causes had more altruistic life goals and reported that compassion was emphasized in their families. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of long-term stress and temperature exposure on the fracture toughness of Ti-62222 alloy

Fracture toughness tests were conducted on a Ti-62222 (titanium alloy) sheet being considered for use in high temperature aircraft applications in the as received condition and after exposing the pre-cracked specimens to a sustained stress intensity, K, level between 55 and 60.5 MPa for 200 h at 350°C. It was concluded that the fracture toughness does not degrade as a result of exposure to high temperature and the K levels in this material. The tensile strength in the exposed condition also remained the same as in the as received condition.