Onset of turbulence in a regular porous medium : An experimental study

Peer reviewedPublisher PD

Community-level characteristics of high infant mortality: A tool to identify at-risk communities

Infant mortality (IM) rate is a key indicator of population health and has been gradually improving in the United States. However, it is still a public health problem among minority and low-income communities. Maternal factors explain some of the variation, but community-level factors may also be a contributor. This study examines measures to identify a set of indicators that explain variations in IM at the community-level. Data for 77 communities in a city were obtained from local health databases. We used multivariable linear regression models to examine the strength of the association between IM and maternal, population, community wealth, and social capital characteristics. Community-level IM rates ranged from 2.1 – 25.6 deaths per 1,000 live births in 2000-2002. The final model explained 75% of the variation in IM rates at the community-level (R2=0.75). The model included a high percentage of low birth weight babies, a decline in mothers who began prenatal care in the second trimester, an increase in the percentage of Hispanics, increased unemployment rates, an increase in the percentage of veterans, an increased rate of foreign-born residents, and smaller average family sizes. Social capital variables, homicide rate and vacant housing, were also significant in the final model. Identifying communities at risk for high IM rates is imperative to improve maternal and child health outcomes because of shortages in public health resources. The development of a parsimonious set of community-level indicators can assist public health practitioners in targeting their resources to prevent infant mortality in high-risk communities

Synergies between processing and memory in children's reading span.

Previous research has established the relevance of working memory for cognitive development. Yet the factors responsible for shaping performance in the complex span tasks used to assess working memory capacity are not fully understood. We report a study of reading span in 7- to 11-year old children that addresses several contemporary theoretical issues. We demonstrate that both the timing and the accuracy of recall are affected by the presence or absence of a semantic connection between the processing requirement and the memoranda. Evidence that there can be synergies between processing and memory argues against the view that complex span simply measures the competition between these activities. We also demonstrate a consistent relationship between the rate of completing processing operations (sentence reading) and recall accuracy. At the same time, the shape and strength of this function varies with the task configuration. Taken together, these results demonstrate the potential for reconstructive influences to shape working memory performance among children

Simultaneous heat and mass transfer in soil columns exposed to freezing/thawing conditions

Soil heat and mass transfer are important processes in nature The effects of soil solution concentration on soil heat and mass transfer have not been investigated thoroughly for freezing/thawing conditions. The objective of this study was to evaluate the SHAW model predictions of heat, water, and chemical transfer in saline and solute-free soils. Heat and mass transfer was studied in closed soil columns. Included were loam soil materials with two salinity levels. Three derivatives of benzoic acid were used as tracers for liquid water movement. Soil was packed into PVC columns that were buried vertically in a field soil profile and exposed to ambient weather conditions. After 72 days, the soil columns were removed from the field and sectioned into 0.02-m increments in order to measure water content, chloride, and benzoic acid tracer distributions. In addition to the observed heat and mass transfer, the SHAW model was used to predict heat and mass transfer in the soil columns. The model described the temperature distributions accurately for both salinized and solute-free soils. Both observed and predicted values of water distribution showed water accumulation in the upper 0.4 m in the solute-free soil. The water diminished slightly in the upper 0.20-m region in the salinized soil columns. Within the salinized soil columns, the final solute distribution did not indicate appreciable net solute movement. The observed and predicted frost depths in the solute-free soil were between 0.45 m and 0.65 m. Freezing was not significant in the salinized soil. The SHAW model should be improved if it is expanded to include the effects of temperature and osmotic potentials on liquid water flow in soil

One Side By Himself: the Life and Times of Lewis Barney, 1808-1894

Review of: One Side by Himself: The Life and Times of Lewis Barney, 1808-1894. Barney, Ronald O