322 research outputs found

    The problem of scale in predicting biological responses to climate

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    This is the final version. Available on open access from Wiley via the DOI in this record Many analyses of biological responses to climate rely on gridded climate data derived from weather stations, which differ from the conditions experienced by organisms in at least two respects. First, the microclimate recorded by a weather station is often quite different to that near the ground surface, where many organisms live. Second, the temporal and spatial resolutions of gridded climate datasets derived from weather stations are often too coarse to capture the conditions experienced by organisms. Temporally and spatially coarse data have clear benefits in terms of reduced model size and complexity, but here we argue that coarse-grained data introduce errors that, in biological studies, are too often ignored. However, in contrast to common perception, these errors are not necessarily caused directly by a spatial mismatch between the size of organisms and the scale at which climate data are collected. Rather, errors and biases are primarily due to (i) systematic discrepancies between the climate used in analysis and that experienced by organisms under study and (ii) the non-linearity of most biological responses in combination with differences in climate variance between locations and time periods for which models are fitted and those for which projections are made. We discuss when exactly problems of scale can be expected to arise and highlight the potential to circumvent these by spatially and temporally down-scaling climate. We also suggest ways in which adjustments to deal with issues of scale could be made without the need to run high-resolution models over wide extents.European Regional Development Fund (ERDF

    Determination of digestible energy values and fermentabilities of dietary fibre supplements: a European interlaboratory study in vivo

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    The performance of methods to determine energy conversion factors for dietary fibre (DF) supplements and fermentability (D) values of their non-starch polysaccharides (NSP) was investigated. Heats of combustion, digestible energy (DE) and D values were determined on five DF supplements in five European laboratories on five separate occasions. In each instance the DF supplements were fed to juvenile male VVistar rats at two doses, 50 and 100 g/kg basal diet, for 3 weeks with food and faeces collected in the 3rd week. Among-laboratory variations in heats of combustion (DHC<) were <2%. DE values (kJ/g dry weight) at the upper and lower doses respectively were: 10·4 and 9·9 for a high-methoxyl apple pectin, 9·5 and 9·4 for a sugar-beet DF supplement, 12·2 and 12·7 for soyabean DF supplement, 38 and 4·0 for maize bran, and 0·3 and 0·3 for Solka-floc cellulose. Variations among laboratories, among occasions and among animals were <1, <2 and <2·5 kJ/g respectively. The among-occasion: among-laboratory variance ratio for DE was 0·5, suggesting the method performed equally well in all laboratories. There was no evidence of learning or fatigue in the performance of the method. D values were also independent of dose and at the high and lower doses were: pectin 0·92 and 0·95, sugar-beet NSP 0·68 and 0·68, soyabean NSP 0·86 and 0·88, maize bran 0·17 and 0·18, cellulose 0·07 and 0·06. Among-laboratory variance tended to increase with decreasing fermentability and ranged from 0·03 to 0·18. The DE and D data were not significantly different from a previously proposed relationship DE = 0·7 × DHc × D, where DHc is the heat of combustion of the supplement. We conclude that while the among-laboratory variation in the D of difficult-to-ferment NSP is too large for the reliable prediction of energy value the method for the direct determination of DE is both reproducible and repeatable, that DE is independent of dosage of DF supplement up to 100 g/kg diet, and that it is safe to discriminate between energy values with a precision of 3 kJ/g. The conversion of both DE and D to net metabolizable energy for the purpose of food labelling, tables and databases is describe

    The Climatic Water Balance and Topography Control Spatial Patterns of Atmospheric Demand, Soil Moisture, and Shallow Subsurface Flow

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    Catchment hydrometeorology and the organization of shallow subsurface flow are key drivers of active contributing areas and streamflow generation. However, understanding how the climatic water balance and complex topography contribute to these processes from hillslope to catchment scales remains difficult. We compared time series of vapor pressure deficits and soil moisture to the climatic water balance and topographic variables across six zero-order catchments in the Lubrecht Experimental Forest (Montana, USA). We then evaluated how local hydrometeorology (volumetric water content and atmospheric vapor pressure deficit) affected the spatial occurrence of shallow subsurface flow. Generalized linear mixed model analysis revealed significant, temporally stable (monthly and seasonal average) patterns of hydrometeorology that can be predicted by the topographic wetness index and the dynamic climatic water deficit (CWD = potential evapotranspiration - actual evapotranspiration). Intracatchment patterns were significantly correlated to the topographic wetness index, while intercatchment patterns were correlated to spatiotemporal variance in the CWD during each time period. Spatial patterns of shallow subsurface flow were related to the hydrometeorological conditions of the site. We observed persistent shallow subsurface flow in convergent hillslope positions, except when a catchment was positioned in locations with high CWDs (low elevations and southerly aspects). Alternatively, we observed persistent subsurface flow across all hillslope positions (even 70-m upslope from the hollow) when catchments were positioned in locations with especially low CWDs (northerly aspects and high elevations). These results highlight the importance of considering the superposition of the catchment-scale climatic water balance and hillslope-scale topography when characterizing hydrometeorology and shallow subsurface flow dynamics.USDA NIFA McIntire Stennis award [233327]; NSF grants [DEB-1457749, DEB-1457720]; NASA applied science program Wildland Fire award [NNH11ZDA001N-FIRES]; NSF EPSCoR through the Montana Institute on Ecosystems6 month embargo; published online: 19 February 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

    Intake of micronutrients among Danish adult users and non-users of dietary supplements

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    Objectives : To evaluate the intake of micronutrients from the diet and from supplements in users and non-users of dietary supplements, respectively, in a representative sample of the Danish adult population. A specific objective was to identify the determinants of supplement use. Design : A cross-sectional representative national study of the intake of vitamins and minerals from the diet and from dietary supplements. Method : The Danish National Survey of Dietary Habits and Physical Activity, 2000–2004. Participants (n=4,479; 53% females) aged 18–75 years gave information about the use of dietary supplements in a personal interview. The quantification of the micronutrient contribution from supplements was estimated from a generic supplement constructed from data on household purchases. Nutrient intakes from the diet were obtained from a self-administered 7-day pre-coded dietary record. Median intakes of total nutrients from the diets of users and non-users of supplements were analysed using the Wilcoxon rank-sum test. Results : Sixty percent of females and 51% of males were users of supplements. With the exception of vitamin D, the intake of micronutrients from the diet was adequate at the group level for all age and gender groups. Among females in the age group 18–49 years, the micronutrient intake from the diet was significantly higher compared with the non-users of dietary supplements. The use of dietary supplements increased with age and with ‘intention to eat healthy.’ Conclusion : Intake of micronutrients from the diet alone was considered adequate for both users and non-users of dietary supplements. Younger females who were supplement users had a more micronutrient-dense diet compared to non-users

    Fine-scale population structure analysis of seven local Swiss sheep breeds using genome-wide SNP data

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    As part of the global sheep Hapmap project, 24 individuals from each of seven indigenous Swiss sheep breeds (Bundner Oberländer sheep (BOS), Engadine Red sheep (ERS), Swiss Black-Brown Mountain sheep (SBS), Swiss Mirror sheep (SMS), Swiss White Alpine (SWA) sheep, Valais Blacknose sheep (VBS) and Valais Red sheep (VRS)), were genotyped using Illumina's Ovine SNP50 BeadChip. In total, 167 animals were subjected to a detailed analysis for genetic diversity using 45193 informative single nucleotide polymorphisms. The results of the phylogenetic analyses supported the known proximity between populations such as VBS and VRS or SMS and SWA. Average genomic relatedness within a breed was found to be 12 percent (BOS), 5 percent (ERS), 9 percent (SBS), 10 percent (SMS), 9 percent (SWA), 12 percent (VBS) and 20 percent (VRS). Furthermore, genomic relationships between breeds were found for single individuals from SWA and SMS, VRS and VBS as well as VRS and BOS. In addition, seven out of 40 indicated parent-offspring pairs could not be confirmed. These results were further supported by results from the genome-wide population cluster analysis. This study provides a better understanding of fine-scale population structures within and between Swiss sheep breeds. This relevant information will help to increase the conservation activities of the local Swiss sheep breed

    Effects of oral semaglutide on energy intake, food preference, appetite, control of eating and body weight in subjects with type 2 diabetes

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    Aim To evaluate the effect of oral semaglutide on energy intake and appetite in subjects with type 2 diabetes (T2D). Materials and Methods In this randomized, double‐blind, placebo‐controlled, two‐period cross‐over trial, 15 subjects with T2D received 12 weeks of treatment with once‐daily oral semaglutide (4‐week dose escalation from 3 to 7 to 14 mg) followed by placebo, or vice versa. Energy intake was measured during an ad libitum lunch, evening meal and snack box after a standard breakfast. Appetite ratings were measured using a visual analogue scale after standard and fat‐rich breakfasts. Other assessments included eating and craving control (using the Control of Eating Questionnaire), and changes in body weight and composition. Results Following a standard breakfast, total daily ad libitum energy intake was significantly lower (38.9%) with oral semaglutide versus placebo in 13 evaluable subjects (estimated treatment difference, −5096.0 kJ; 95% CI –7000.0, −3192.1; P = .0001). After a fat‐rich breakfast, there were significant differences in favour of oral semaglutide versus placebo for measures of satiety, hunger and for overall appetite score, with no significant differences following a standard breakfast. Fewer food cravings and better eating control were seen with oral semaglutide versus placebo. Overall, mean body weight decreased by 2.7 kg with oral semaglutide and 0.1 kg with placebo, mostly attributable to body fat mass loss. Conclusion After 12 weeks of treatment, ad libitum energy intake was lower with oral semaglutide versus placebo, resulting in reduced body fat mass, and was associated with increased satiety and fullness after a fat‐rich breakfast, and improved eating control

    Whole grain foods and health - A Scandinavian perspective

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    The food-based dietary guidelines in the Scandinavian countries that recommend an intake of minimum 75 g whole grain per 10 MJ (2,388 kcal) per day are mainly derived from prospective cohort studies where quantitative but little qualitative details are available on whole grain products. The objective of the current paper is to clarify possible differences in nutritional and health effects of the types of whole grain grown and consumed in the Scandinavian countries. A further objective is to substantiate how processing may influence the nutritional value and potential health effects of different whole grains and whole grain foods. The most commonly consumed whole grain cereals in the Scandinavian countries are wheat, rye, and oats with a considerable inter-country variation in the consumption patterns and with barley constituting only a minor role. The chemical composition of these different whole grains and thus the whole grain products consumed vary considerably with regard to the content of macro- and micronutrients and bioactive components. A considerable amount of scientific substantiation shows that processing methods of the whole grains are important for the physiological and health effects of the final whole grain products. Future research should consider the specific properties of each cereal and its processing methods to further identify the uniqueness and health potentials of whole grain products. This would enable the authorities to provide more specific food-based dietary guidelines in relation to whole grain to the benefit of both the food industry and the consumer

    Weather, disease, and wheat breeding effects on Kansas wheat varietal yields, 1985 to 2011.

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    Wheat (Triticum aestivum L.) yields in Kansas have increased due to wheat breeding and improved agronomic practices, but are subject to climate and disease challenges. The objective of this research is to quantify the impact of weather, disease, and genetic improvement on wheat yields of varieties grown in 11 locations in Kansas from 1985 to 2011. Wheat variety yield data from Kansas performance tests were matched with comprehensive location-specific disease and weather data, including seasonal precipitation, monthly air temperature, air temperature and solar radiation around anthesis, and vapor pressure deficit (VPD). The results show that wheat breeding programs increased yield by 34 kg ha⁻¹ yr⁻¹. From 1985 through 2011, wheat breeding increased average wheat yields by 917 kg ha⁻¹, or 27% of total yield. Weather was found to have a large impact on wheat yields. Simulations demonstrated that a 1°C increase in projected mean temperature was associated with a decrease in wheat yields of 715 kg ha⁻¹, or 21%. Weather, diseases, and genetics all had significant impacts on wheat yields in 11 locations in Kansas during 1985 to 2011
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