Analysis of mixtures of drugs/chemicals along a fixed-ratio ray without single-chemical data to support an additivity model

This article presents and illustrates an approach to designing and analyzing studies involving mixtures/combinations of drugs or chemicals along fixed-ratio rays of the drugs or chemicals for generalized linear models. When interest can be restricted to a specific ray, we consider fixed-ratio ray designs to reduce the amount of experimental effort. When a ray design is used, we have shown that the hypothesis of additivity can be rejected when higher order polynomial terms are required in the total dose-response model. Thus, it is important that we have precise parameter estimates for these higher order polynomial terms in the linear predictor. We have developed methodology for finding a D _s -optimal design based on this subset of the terms in the linear predictor.     

Functional diversity vs. monotony: the effect of a multiforage diet as opposed to a single forage diet on animal intake,performance, welfare,and urinary nitrogen excretion

The objective of this study was to determine the effect of offering animals a multiforage choice (MF) of fresh herbages on dry matter intake (DMI), live weight gain, and animal welfare, in comparison with a monotonous diet of ryegrass (Lolium perenne L.). Twenty ram lambs (30.5 ± 0.9 kg initial live weight; mean ± SEM), were randomly allocated to either a diet consisting of diverse MF choice or a single forage ryegrass (SF) diet (n = 10 per treatment) for 35 d. Both diets were fed ad libitum; however, the MF diet was composed of set dry matter ratios of 24% chicory (Cichorium intybus L.), 30% lucerne (Medicago sativa L.), 25% plantain (Plantago lanceolata L.), and 21% ryegrass. The DMI of the MF lambs was 48% greater (P < 0.01) and the within animal day-to-day coefficient of variation (CV) of intake was 26% lower (P < 0.01) than the SF lambs. The average daily gain (ADG) of lambs offered the MF diet was 92% greater (P < 0.01) than the lambs offered the SF diet. The within-animal day-to-day CV of intake was negatively related to ADG (r = −0.59; P < 0.01). The MF lamb’s urinary N concentration was 30% lower (P < 0.01) than that of the SF lambs. The SF lambs spent more time (P < 0.05) exhibiting stereotypic behaviors in the afternoon and spent more time observing other animals than the MF. Overall, allocating an MF choice of fresh herbages as opposed to a single forage diet of ryegrass increases DMI and thereby animal performance, while potentially reducing urinary N excretion.     

Cellular and subcellular compartmentation of sulphate in leaves in relation to low sulphur mobility

Tracer kinetics and single cell sampling both suggest that S is compartmented differently in vacuoles of epidermal and mesophyll cells. Cytoplasmic S turns over rapidly, but vacuolar turnover in both cell types is too slow to support plant growth, thus accounting in part for the apparent low mobility of S in mature leaves.     

Tin streaming and channel changes some preliminary observations from Dartmoor, England

The valley floor of the North Teign River on Dartmoor has been much modified by tin streaming activity, particularly during the nineteenth century. Field measurements of channel size at sample sites along the river were collected, to asses whether the tin streamed reaches had undergone observable channel changes. Close similarities in the relationships between channel size and drainage area for both natural and streamed sites suggest that no real channel changes are apparent at the present time, but differences in the relationships between channel size and total stream length for the natural and streamed sites show that the uppermost natural sites are considerably larger than the streamed sites at similar locations. Integration of the relationships between channel size and total stream length allows a comparison of estimated total network volumes for the streamed and natural sites, and the estimated volume for the streamed river is about 18 % smaller than that of the natural channel over the same reach. Channel change is believed to be related to changes in the size composition of sediment load in the stream, occasioned by the modified distribution of valley floor sediments brought about by the streaming activities.     

The impact of high non-starch polysaccharide intake on serum micronutrient concentrations in a cohort of women

OBJECTIVE: Many public health campaigns encourage increased fibre consumption, but short-term studies suggest that various components of dietary fibre inhibit the absorption of certain micronutrients including carotenoids. These do not take into account long-term adaptation to nutrient intake levels. We aimed to investigate the effect of non-starch polysaccharide (NSP) fibre on plasma micronutrient concentrations in a large free-living population consuming their usual diet. DESIGN: Prospective cohort study. Semi-weighed 4-day food diaries were analysed for micronutrient and NSP fibre intakes. Blood samples were taken and analysed for carotenoids, vitamin A, vitamin E, thiamine, riboflavin, vitamin B6, vitamin B12, folic acid, vitamin C and trace metals. SETTING: Participants in a large national cohort study who lived within 30 miles of Leeds. SUBJECTS: Two hundred and eighty-three middle-aged women. RESULTS: The association between NSP intake and plasma nutrient concentrations was assessed taking into account nutrient intakes and other dietary and lifestyle factors. Higher levels of NSP were not associated with lower plasma concentrations of the micronutrients measured, even allowing for the higher nutrient levels generally found in high-fibre foods. CONCLUSIONS: Amongst middle-aged women we have shown that current guidelines for increasing the population's NSP consumption can be safely applied. Such guidelines are unlikely to reduce serum micronutrient concentrations, although other, more vulnerable population groups may benefit from further investigation.     

A bayesian approach to regional and local-area prediction from crop variety trials

The inclusion of covariates in models for analyzing variety × environmental data sets allows the estimation of variety yields for specific locations within a region as well as for the region as a whole. Here we explore a Bayesian approach to the estimation of such effects and to the choice of variety using a possibly incomplete variety × location × year data set that includes location × year covariates. This approach allows expert knowledge of the crop and uncertainty about local circumstances to be incorporated in the analysis. It is implemented using Markov chain Monte Carlo simulation. An example is used to illustrate the approach and investigate its robustness.     

Canopy processes in a changing climate

Forest canopies exchange a large part of the mass and energy between the earth and the atmosphere. The processes that regulate these exchanges have been of interest to scientists from a diverse range of disciplines for a long time. The International Union of Forest Research Organizations (IUFRO) Canopy Processes Working Group provides a forum for these scientists to explore canopy processes at scales ranging from the leaf to the ecosystem. Given the changes in climate that are being experienced in response to rising [CO(2)], there is a need to understand how forest canopy processes respond to altered environments. Globally, native and managed forests represent the largest terrestrial biome and, in wood and soils, the largest terrestrial stores of carbon. Changing climates have significant implications for carbon storage in forests, as well as their water use, species diversity and management. In order to address these issues, the Canopy Processes Working Group held a travelling workshop in south-east Australia during October 2010 to examine the impact of changing climates on forest canopies, highlighting knowledge gaps and developing new research directions.     

Genetic and environmental variation in wood properties of <Emphasis Type="Italic">Acacia melanoxylon</Emphasis>

Context  

Australian blackwood (Acacia melanoxylon), is a fast-growing, high-quality, appearance-grade timber species native to eastern Australia. Some of its key wood properties are percentage heartwood, heartwood colour, basic density, wood stiffness and green moisture content. Variation in these properties affects log value, processing and marketing.