Delayed surgical debridement in pediatric open fractures: a systematic review and meta-analysis.

Purpose: Open fractures are considered orthopedic emergencies that are traditionally treated with surgical debridement within 6 h of injury to prevent infection. However, this proclaimed “6-h rule” is arbitrary and not based on rigorous scientific evidence. The aim of our study was to systematically review the literature that compares late (>6 h from the time of injury) to early (<6 h from the time of injury) surgical debridement of pediatric open fractures. Methods: We searched several databases from 1946 to 2013 for any observational or experimental studies that evaluated late and early surgical debridement of pediatric open fractures. We performed a meta-analysis using a random effects model to pool odds ratios for a comparison of infection rates between children undergoing late versus early surgical debridement. We also investigated the infection rates in upper- and lower-limb pediatric open fractures. Descriptive, quantitative, and qualitative data were extracted. Results: Of the 12 articles identified, three studies (retrospective cohort studies) were eligible for the meta-analysis, encompassing a total of 714 open fractures. The pooled odds ratio (OR = 0.79) for infection between late and early surgical debridement was in favor of late surgical debridement but was not statistically significant (95 % CI 0.32, 1.99; p = 0.38, I 2 = 0 %). No significant difference in infection rate was detected between pediatric open fractures in the upper and lower limbs according to the time threshold in the included studies (OR = 0.72, 95 % CI 0.29, 1.82; p = 0.40, I 2 = 0 %). Conclusions: The cumulative evidence does not, at present, indicate an association between late surgical debridement and higher infection rates in pediatric open fractures. However, initial expedient surgical debridement of open fractures in children should always remain the rule. Thus, multi-center randomized controlled trials or prospective cohort studies will be able to answer this question with more certainty and a higher level of evidence

Optimal management of irrigation and vadose zone pesticide transport

A management model is developed for maximizing crop yield while avoiding unacceptable pesticide leaching. Utilized constraint equations: maintain a soil moisture volume balance, describe downward pesticide transport, and limit the amount of pesticide reaching groundwater. The reported optimization model is the first which includes unsaturated zone pesticide transport. It is designed to help prevent nonpoint-source contamination of shallow groundwater aquifers. The model computes optimal irrigation amounts for given soil, crop, chemical, and climate data and irrigation frequencies. The model is tested for different irrigation scenarios. The modeling approach is promising as a tool to aid developing environmentally sound agricultural production practices. It allows estimation of trade-offs between crop production and groundwater protection for different management strategies. More frequent irrigation tends to give better crop production and less solute movement. Yield/environmental quality trade-offs are smaller for deeper groundwater tables. Trade-offs also decrease with increased irrigation frequency

How Viable Is the UTAUT Model in a Non-Western Context?

The present research examines the plausibility of Unified Theory Acceptance and Use Technology (UTAUT) model in predicting internet banking behaviour as a newly adopted technology third world countries. Data is collected from three Arab countries: Jordan, Saudi Arabia and Egypt. Confirmatory factor analysis is applied to test constructs measurement and model hypotheses. Findings are congruent with model testing under conditions of volitional usage behaviour. In this regard, the role of facilitating conditions variable is insignificant as a determinant of usage behaviour. Social norms variable also proved to be weak determinant of behavioural intentions mainly owing to users’ experience. Findings demonstrate effort expectancy as the key determinant of internet banking usage behaviour in the examined markets, while users’ experience moderates the impact of effort expectancy on behavioural intention. Results should enhance our understanding of internet banking usage in developing countries and support e-services promoting in this region

Preventing pesticide contamination of groundwater while maximizing irrigated crop yield

A simulation/optimization model is developed for maximizing irrigated crop yield while avoiding unacceptable pesticide leaching. The optimization model is designed to help managers prevent non-point source contamination of shallow groundwater aquifers. It computes optimal irrigation amounts for given soil, crop, chemical, and weather data and irrigation frequencies. It directly computes the minimum irrigated crop yield reduction needed to prevent groundwater contamination. Constraint equations used in the model maintain a layered soil moisture volume balance; describe percolation, downward unsaturated zone solute transport and pesticide degradation; and limit the amount of pesticide reaching groundwater. Constraints are linear, piecewise linear, nonlinear, and exponential. The problem is solved using nonlinear programming optimization. The model is tested for different scenarios of irrigating corn. The modeling approach is promising as a tool to aid in the development of environmentally sound agricultural production practices. It allows direct estimation of trade-offs between crop production and groundwater protection for different management approaches. More frequent irrigation tends to give better crop yield and reduce solute movement. Trade-offs decrease with increasing irrigation frequency. More frequent irrigation reduces yield loss due to moisture stress and requires less water to fill the root zone to field capacity. This prevents the solute from moving to deeper soil layers. Yield-environmental quality trade-offs are smaller for deeper groundwater tables because deeper groundwater allows more time for chemical degradation

Influencia de distintas fuentes de sílice en las propiedades físicas y mecánicas de materiales derivados del yeso

Gypsum plaster/silica composites prepared by dry blending (0.2-10 %) natural sand, silica fume or silica gel and subsequently hydrated. Their physical and mechanical properties, including normal consistency, setting time, apparent porosity, bulk density and compressive strength, were determined after hydration for 7- and 28-days. The results indicated that adding different forms of silica lowered the bulk density and increased the normal consistency, setting time, apparent porosity and, to some limited extent, compressive strength of the composites. This improvement in properties can be attributed to the existence of silica in the interstitial pores in the hardened plaster matrices. While most of the composites revealed only scant rises in compressive strength, their composition was beneficial in so far as it included either a readily available low-cost constituent (sand) or industrial by-products. Consequently, the formed plaster-silica composites are of economic value, contribute to a cleaner environment by minimizing waste and can be used for applications where high porosity, lightweight units are required or recommended for low-cost buildings.Se prepararon pastas compuestas de yeso y sílice mediante la mezcla en seco de yeso con distintas proporciones (0,2- 10 %) de arena natural, o gel o humo de sílice, procediéndose a continuación a su hidratación. A fin de determinar las propiedades físicas y mecánicas de las pastas, a los 7 y los 28 días de hidratación se hallaron su fluidez, tiempo de fraguado, porosidad aparente, densidad aparente y resistencia a la compresión. Los resultados obtenidos indican que al incorporar las distintas modalidades de sílice a la mezcla, disminuyó la densidad aparente y aumentaron la fluidez, el tiempo de fraguado, la porosidad aparente y, en menor medida, la resistencia a la compresión de las muestras. Se considera que esta mejora de las propiedades del material se debe a la presencia de sílice en los poros intersticiales de las matrices endurecidas de yeso. Aunque la resistencia a la compresión de la mayoría de las pastas ensayadas apenas aumentó, estas se beneficiaron de la presencia en su composición de elementos de bajo coste como la arena o los distintos subproductos industriales utilizados. Puede concluirse, por lo tanto, que los compuestos de yeso y sílice tienen valor económico y contribuyen a mejorar el medioambiente al valorizar residuos. Por otra parte, son apropiados para las aplicaciones en las que se necesitan o recomiendan elementos de alta porosidad y bajo peso, concretamente en las edificaciones bajas