Optimal sampling locations to reduce uncertainty in contamination extent in water distribution systems.

Drinking water utilities rely on samples collected from the distribution system to provide assurance of water quality. If a water contamination incident is suspected, samples can be used to determine the source and extent of contamination. By determining the extent of contamination, the percentage of the population exposed to contamination, or areas of the system unaffected can be identified. Using water distribution system models for this purpose poses a challenge because significant uncertainty exists in the contamination scenarios (e.g., injection location, amount, duration, customer demands, contaminant characteristics). This article outlines an optimization framework to identify strategic sampling locations in water distribution systems. The framework seeks to identify the best sampling locations to quickly determine the extent of the contamination while considering uncertainty with respect to the contamination scenarios. The optimization formulations presented here solve for multiple optimal sampling locations simultaneously and efficiently, even for large systems with a large uncertainty space. These features are demonstrated in two case studies.

The Venezuela eye evaluation study.

UNLABELLED: One-thousand-eighty-one rural and urban inhabitants of Venezuela were discovered to have good uncorrected visual acuity. This was especially noted among the males who were examined. More myopia was seen than previously reported, while earlier presbyopia was confirmed. There was a relatively low prevalence of glaucoma among men and women. Correction of refractive errors, cataracts, glaucoma and pterygia remains a challenge. OBJECTIVE: To determine the frequency of ocular disease in rural and urban Venezuela. DESIGN: Participants in a cross-sectional health screening study were examined. The main outcome measured was external eye disease: allergic conjunctivitis, dry eyes and pterygia. RESULTS: A total of 1,281 individuals participated. All agreed to screening and eye examinations. Open-angle glaucoma was present in 1.2% of women and 1% of men. For participants age > 45, this increased to 1.9% of women and 2.8% of men. CONCLUSIONS: Rural and urban inhabitants of Venezuela were determined to have good uncorrected visual acuity, especially among males. More myopia was noted than previously reported, while earlier presbyopia was confirmed. There was a relatively low frequency of glaucoma among men and women as compared to Barbados, and a U.S.-based study of Mexican Americans.

Floral movements in response to thunderstorms improve reproductive effort in the alpine species Gentiana algida (Gentianaceae).

Studies of floral movements in response to environmental change are rare in the literature, and information about possible adaptive benefits appears nonexistent. The closure of the upright, tubular flowers of alpine gentian (Gentiana algida) were observed during the frequent afternoon thunderstorms characteristic of the central and southern Rocky Mountains (USA). Flowers closed within minutes of an approaching thunderstorm and reopened after direct sunlight returned. Corolla opening widths decreased ∼10%/min prior to rainfall, in close correspondence to declines in air and corolla temperatures. Identical floral behavior was also induced experimentally in the field and laboratory by artificial changes in corolla temperature. Corolla closure did not occur during experiments that simulated natural changes in solar irradiance, wind, or absolute humidity during a thunderstorm. Furthermore, individual G. algida plants forced experimentally to remain open during rain had substantial losses of pollen after single rain events (up to 34%) and if forced to remain open for the entire flowering period (59%). Subsequent seasonal reductions in female fitness (up to 73%) also occurred, including seed size and mass, number of ovules produced, number of viable seeds produced per ovule, and seed germination. Thus, corolla closing and opening in G. algida associated with frequent summer thunderstorms may be a behavioral adaptation that improves both paternal and maternal reproductive effort.

African American single mothers and children in context: a review of studies on risk and resilience.

This paper presents a comprehensive review of research linking single-parent family structure to parenting processes, maternal well-being, and child developmental outcomes among African Americans. The approaches used to study these families, related methodological and conceptual concerns, and the factors linked to maternal well-being, effective parenting processes, family functioning, and child outcomes are addressed. Much work remains to be done on conceptualizing and assessing parenting processes among African Americans in general and single African American mothers in particular. Researchers must examine more carefully the circumstances that foster or impede successful parenting among these mothers. Studies also are needed to disentangle the interactions between economic stress and parenting behavior and to determine the extent to which the findings can be applied to middle-income single African American parents.

Children of divorce and its effect on their self-esteem.

The purpose was to investigate the temporal relationship of divorce with self-esteem of children and to assess differences in self-esteem, if any, between children of divorced families and children of intact families. The self-esteem of 60 children in Grade 9 and from divorced homes was measured using the Culture-free Self-esteem inventory. There was no significant positive correlation between the passage of time and higher self-esteem among these children. Independent t tests were then computed using the inventory scores of 60 students in Grade 9 from homes with both parents and the 60 from homes of divorced parents. Significant differences in self-esteem were found between the two groups.