How explicable are differences between reviews that appear to address a similar research question? A review of reviews of physical activity interventions

Background Systematic reviews are promoted as being important to inform decision-making. However, when presented with a set of reviews in a complex area, how easy is it to understand how and why they may differ from one another? Methods An analysis of eight reviews reporting evidence on effectiveness of community interventions to promote physical activity. We assessed review quality and investigated overlap of included studies, citation of relevant reviews, consistency in reporting, and reasons why specific studies may be excluded. Results There were 28 included studies. The majority (n = 22; 79%) were included only in one review. There was little cross-citation between reviews (n = 4/28 possible citations; 14%). Where studies appeared in multiple reviews, results were consistently reported except for complex studies with multiple publications. Review conclusions were similar. For most reviews (n = 6/8; 75%), we could explain why primary data were not included; this was usually due to the scope of the reviews. Most reviews tended to be narrow in focus, making it difficult to gain an understanding of the field as a whole. Conclusions In areas where evaluating impact is known to be difficult, review findings often relate to uncertainty of data and methodologies, rather than providing substantive findings for policy and practice. Systematic ‘maps’ of research can help identify where existing research is robust enough for multiple in-depth syntheses and also show where new reviews are needed. To ensure quality and fidelity, review authors should systematically search for all publications from complex studies. Other relevant reviews should be searched for and cited to facilitate knowledge-building

A liquid tin dispenser arc cathode

Imperial Users onl

Distribution and Control of Herbicide-Resistant Italian Ryegrass (Lolium perenne L. ssp. multiflorum Lam. Husnot) in Arkansas

Italian ryegrass populations have evolved resistance to herbicides that producers rely on for weed control both in wheat and burn-down. The objectives of this research were to: test populations of Italian ryegrass from across Arkansas for resistance to glyphosate, diclofop, pinoxaden, and pyroxsulam; determine if there were any differences in control of 12 glyphosate-resistant populations in relation to glyphosate rate or application timing; determine the level of glyphosate resistance in one selected population versus a susceptible standard and a previously discovered glyphosate-resistant population; and determine the best options for controlling Italian ryegrass prior to planting crops. A total of 215 population samples were tested. On average 17% of the samples were resistant to glyphosate, 95% were resistant to diclofop, 64% were resistant to pyroxsulam, and 12% were resistant to pinoxaden. A few were resistant to all four chemistries tested. Control of glyphosate-resistant populations was improved with the high rate of glyphosate at the three- to four-tiller growth stage; however, results for individual populations were variable. When averaged across populations, no rate or timing of glyphosate controlled these resistant populations greater than 62%. One population was found to be 23 times more tolerant to glyphosate than a susceptible standard. Three field experiments were conducted for Italian ryegrass control in the spring, in no-till production in the fall, and following fall tillage. Herbicide applications in the spring were unsuccessful, especially when glyphosate is not an option. Even when postemergence (POST) treatments visually controlled ryegrass at least 80%, enough ryegrass residue remained that would cause problems with spring tillage, planting, and overall crop stand establishment. In the fall-tilled study, the residual herbicides flumioxazin plus S-metolachlor, S-metolachlor, clomazone, and pyroxasulfone applied immediately following fall tillage reduced Italian ryegrass biomass by 83 to 95% at 200 days after treatment

The preparation and properties of isolated chicken hepatocytes

Chicken hepatic parenchymal cell suspensions, isolated by an optimised collagenase digestion, were used for a study of hepatic glucose metabolism and its control in the chicken. Characterisation of this iri vitro preparation showed the parenchymal cells immediately after isolation to be similar to those of whole liver, both morphologically and metabolically. This similarity suggested that metabolic studies with isolated hepatocytes might confidently be extrapolated to the situation in the intact animal. However the preparation quality was dependent on collagenase contaminants and all preparations exhibited decreased viability throughout subsequent incubations.Glycogen metabolism in isolated hepatocyte suspensions favoured glycogenolysis and under no conditions was net glycogen synthesis observed. Gluconeogenesis from added precursors was difficult to discern with fed chicken hepatocytes due to the high basal glucose production but was readily demonstrated at a constant rate over a two hour incubation with starved chicken hepatocytes.The gluconeogenic effectiveness of precursors was generally similar in isolated hepatocytes and in chickens in vivo. The greater effectiveness of lactate compared with pyruvate, observed with both systems (unlike the rat), is probably a consequence of impaired hydrogen ion transfer during pyruvate gluconeogenesis due to the mitochondrial location of phosphoenolpyruvate carbcxykinase in the chicken. Synergistic interactions between substrates were shown to occur and be important for interpretation of results from isolated hepatocytes for extrapolation to the situation in vivo. Glycerol wasPhysiological concentrations of glucagon stimulated glycogenolysis and gluconeogenesis from precursors entering the glycolytic pathway above and below the triose phosphate dehydrogenase step. Although it was possible to assign a glucagon control point between triose phosphate and glucose in chicken liver, that between pyruvate and phosphoenol pyruvate (postulated for the rat) was not observed

Conceptual Overburden in the System\u27s Operation?: Of Judges and Scholars, Jurisdiction and All That

A Review of Federal Practice and Procedure, Volumes 13-19: Jurisdiction and Related Matters by Charles Alan Wright, Arthur R. Miller, and Edward H. Coope