921 research outputs found
Effect of light intensity and wavelength on concentration of plant secondary metabolites in the leaves of Flourensia cernua
Flourensia cernua (tarbush) is a shrub that has encroached into grasslands in many areas of the northern Chihuahuan Desert and contains high levels of carbon-based secondary compounds. Concentrations of secondary compounds are affected by numerous biotic and abiotic influences, including amount and wavelength of solar radiation. However, responses to shade and ultraviolet light restriction are inconsistent among plant species and compound class. We conducted a three-year study to evaluate the effect of shade and UV light restriction on total phenolic and terpene concentrations in tarbush. Sixty plants were randomly assigned to one of three treatments (control, UV light restriction, or 50% incident light restriction). Mean concentrations of total phenolics and total volatiles in tarbush were 82.4 and 12.5 mg/g DM, respectively. Total phenolics did not differ between UV-restricted and control plants, but were lower in shaded plants than the other treatments (P \u3c 0.05). Total volatiles tended to be greater for the UV-restricted treatment than control plants (P = 0.056), with shaded plants not different from either treatment. Treatment effects were detected for 18 individual compounds (P \u3c 0.05). Our results partially support the hypothesis that UV restriction and shading alter carbon-based secondary chemical concentrations
BCKDH: the missing link in apicomplexan mitochondrial metabolism is required for full virulence of Toxoplasma gondii and Plasmodium berghei
While the apicomplexan parasites Plasmodium falciparum and Toxoplasma gondii are thought to primarily depend on glycolysis for ATP synthesis, recent studies have shown that they can fully catabolize glucose in a canonical TCA cycle. However, these parasites lack a mitochondrial isoform of pyruvate dehydrogenase and the identity of the enzyme that catalyses the conversion of pyruvate to acetyl-CoA remains enigmatic. Here we demonstrate that the mitochondrial branched chain ketoacid dehydrogenase (BCKDH) complex is the missing link, functionally replacing mitochondrial PDH in both T. gondii and P. berghei. Deletion of the E1a subunit of T. gondii and P. berghei BCKDH significantly impacted on intracellular growth and virulence of both parasites. Interestingly, disruption of the P. berghei E1a restricted parasite development to reticulocytes only and completely prevented maturation of oocysts during mosquito transmission. Overall this study highlights the importance of the molecular adaptation of BCKDH in this important class of pathogens
A randomised trial of an internet weight control resource: The UK Weight Control Trial [ISRCTN58621669]
BACKGROUND:
Obesity treatment is notoriously unsuccessful and one of the barriers to successful weight loss reported by patients is a lack of social support. The Internet offers a novel and fast approach to the delivery of health information, enabling 24-hour access to help and advice. However, much of the health information available on the Internet is unregulated or not written by qualified health professionals to provide unbiased information. The proposed study aims to compare a web-based weight loss package with traditional dietary treatment of obesity in participants. The project aims to deliver high quality information to the patient and to evaluate the effectiveness of this information, both in terms of weight loss outcomes and cost-effectiveness.
METHODS:
This study is a randomised controlled trial of a weight loss package against usual care provided within General Practice (GP) surgeries in Leeds, UK. Participants will be recruited via posters placed in participating practices. A target recruitment figure of 220 will enable 180 people to be recruited (allowing for 22% dropout). Participants agreeing to take part in the study will be randomly allocated using minimisation to either the intervention group, receiving access to the Internet site, or the usual care group. The primary outcome of the study will be the ability of the package to promote change in BMI over 6 and 12 months compared with traditional treatment. Secondary outcomes will be the ability of the Internet package to promote change in reported lifestyle behaviours. Data will be collected on participant preferences, adherence to treatment, health care use and time off work. Difference in cost between groups in provision of the intervention and the cost of the primary outcome will also be estimated.
CONCLUSION:
A positive result from this study would enhance the repertoire of treatment approaches available for the management of obesity. A negative result would be used to inform the research agenda and contribute to redefining future strategies for tackling obesity
A novel route for volume manufacturing of hollow braided composite beam structures
This work investigates the application of a rapid variothermal moulding process for direct processing of a braided thermoplastic commingled yarn. The process uses locally controllable, responsive tooling which provides opportunities for optimum part quality and significantly reduced cycle times compared with conventional processes. The proposed process was used to directly manufacture hollow beam structures from dry commingled braided preforms. It was demonstrated that the cycle time using the rapid process was reduced by more than 90% as compared to a conventional bladder moulding process, resulting in a total cycle time of 14 min. Additionally, initial three point flexure test results indicated an improvement in the mechanical performance of the resultant parts as compared to the benchmark
Association among plasma levels of monocyte chemoattractant protein-1, traditional cardiovascular risk factors, and subclinical atherosclerosis
ObjectivesWe sought to evaluate the association between plasma levels of monocyte chemoattractant protein (MCP)-1 and the risk for subclinical atherosclerosis.BackgroundMonocyte chemoattractant protein is a chemokine that recruits monocytes into the developing atheroma and may contribute to atherosclerotic disease development and progression. Plasma levels of MCP-1 are independently associated with prognosis in patients with acute coronary syndromes, but few population-based data are available from subjects in earlier stages of atherosclerosis.MethodsIn the Dallas Heart Study, a population-based probability sample of adults in Dallas County ≤65 years old, plasma levels of MCP-1 were measured in 3,499 subjects and correlated with traditional cardiovascular risk factors, high-sensitivityC-reactive protein (hs-CRP), and coronary artery calcium (CAC) measured by electron beam computed tomography.ResultsHigher MCP-1 levels were associated with older age, white race, family history of premature coronary disease, smoking, hypertension, diabetes, hypercholesterolemia, and higher levels of hs-CRP (p < 0.01 for each). Similar associations were observed between MCP-1 and risk factors in the subgroup of participants without detectable CAC. Compared with the subjects in the lowest quartile of MCP-1, the odds of prevalent CAC (CAC score ≥10) for subjects in the second, third, and fourth quartiles were 1.30 (95% confidence interval [CI] 0.99 to 1.73), 1.60 (95% CI 1.22 to 2.11), and 2.02 (95% CI 1.54 to 2.63), respectively. The association between MCP-1 and CAC remained significant when adjusted for traditional cardiovascular risk factors, but not when further adjusted for age.ConclusionsIn a large population-based sample, plasma levels of MCP-1 were associated with traditional risk factors for atherosclerosis, supporting the hypothesis that MCP-1 may mediate some of the atherogenic effects of these risk factors. These findings support the potential role of MCP-1 as a biomarker target for drug development
How oviform is the chicken egg? New mathematical insight into the old oomorphological problem
The chicken egg, a major food product, has been, as a model oviform object, the focus of advanced description in mathematical terms, and such a description has practical applications in engineering, industrial and biological disciplines. A precise mathematical description circumscribing major oomorphological characteristics, coupled with their non-destructive measurement, remains, to a certain extent, problematic and has not yet been achieved, hampering their effective control and use. A contour of any chicken egg can be accurately defined with Hügelschäffer's model by means of three main measures: length, L, maximum breadth, B, and a parameter w that corresponds to a distance of shifting the ellipse center to form an egg ovoid. The goal of the study was a comprehensive theoretical evaluation and development of basic geometrical formulae to define egg external traits by using Hügelschäffer's model and employing simulation modelling, digital imaging and image processing. As a result, we deduced novel geometrical formulae for the egg long circumference, C, volume, V, area of a plane curve obtained by the normal/orthogonal projection, A, surface area, S, distance parameter, w, and radius of curvature, R, at any point on the x-axis. For practical use in the poultry industry and food engineering, the proposed formulae can be instrumental in the non-destructive and accurate definition of the external parameters of any chicken egg
A 2-D imaging-assisted geometrical transformation method for non-destructive evaluation of the volume and surface area of avian eggs
Egg volume and surface area are reliable predictors of quality traits for both table and hatching chicken eggs. A new non-destructive technique for the fast and accurate evaluation of these two egg variables is addressed in the present study. The proposed method is based on the geometrical transformation of actual egg contour into a well-known geometrical figure which shape most of all resembles the examined egg. The volume and surface area of an examined egg were recomputed using the formulae appropriate for three figures including sphere, ellipsoid, and egg-shape ovoid. The method of the geometrical transformation includes the measurements of the egg length and the area of the examined eggs. These variables were determined using two-dimensional (2-D) digital imaging and image processing techniques. The geometrical transformation approach is proven to be reliable to turn the studied chicken eggs into the three chosen ovoid models, with the best prediction being shown for the ellipsoid and egg-shape ovoid, whilst the former was slightly more preferable. Depending on the avian species studied, we hypothesise that it would be more suitable to use the sphere model for more round shaped eggs and the egg-shaped ovoid model if the examined eggs are more conical. The choice of the proposed transformation technique would be applicable not only for the needs of poultry industry but also in ornithological, basically zoological studies when handling the varieties of eggs of different shapes. The experimental results show that the method proposed is accurate, reliable, robust and fast when coupled and assisted with the digital imaging and image processing techniques, and can serve as a basis for developing an appropriate instrumental technology and bringing it into the practice of poultry enterprises and hatcheries
Bridging Thermal Infrared Sensing and Physically-Based Evapotranspiration Modeling : From Theoretical Implementation to Validation Across an Aridity Gradient in Australian Ecosystems
Thermal infrared sensing of evapotranspiration (E) through surface energy balance (SEB) models is challenging due to uncertainties in determining the aerodynamic conductance (g(A)) and due to inequalities between radiometric (T-R) and aerodynamic temperatures (T-0). We evaluated a novel analytical model, the Surface Temperature Initiated Closure (STIC1.2), that physically integrates T-R observations into a combined Penman-Monteith Shuttleworth-Wallace (PM-SW) framework for directly estimating E, and overcoming the uncertainties associated with T0 and gA determination. An evaluation of STIC1.2 against high temporal frequency SEB flux measurements across an aridity gradient in Australia revealed a systematic error of 10-52% in E from mesic to arid ecosystem, and low systematic error in sensible heat fluxes (H) (12-25%) in all ecosystems. Uncertainty in TR versus moisture availability relationship, stationarity assumption in surface emissivity, and SEB closure corrections in E were predominantly responsible for systematic E errors in arid and semi-arid ecosystems. A discrete correlation (r) of the model errors with observed soil moisture variance (r = 0.33-0.43), evaporative index (r = 0.77-0.90), and climatological dryness (r = 0.60-0.77) explained a strong association between ecohydrological extremes and T-R in determining the error structure of STIC1.2 predicted fluxes. Being independent of any leaf-scale biophysical parameterization, the model might be an important value addition in working group (WG2) of the Australian Energy and Water Exchange (OzEWEX) research initiative which focuses on observations to evaluate and compare biophysical models of energy and water cycle components. Plain Language Summary Evapotranspiration modeling and mapping in arid and semi-arid ecosystems are uncertain due to empirical approximation of surface and atmospheric conductances. Here we demonstrate the performance of a fully analytical model which is independent of any leaf-scale empirical parameterization of the conductances and can be potentially used for continental scale mapping of ecosystem water use as well as water stress using thermal remote sensing satellite data.dPeer reviewe
The social network structure of a dynamic group of dairy cows:from individual to group level patterns
ArticleSocial relationships have been shown to significantly impact individual and group success in wild animal populations, but are largely ignored in farm animal management. There are substantial gaps in our knowledge of how farm animals respond to their social environment, which varies greatly between farms but is commonly unstable due to regrouping. Fundamental to addressing these gaps is an understanding of the social network structure resulting from the patterning of relationships between individuals in a group. Here, we investigated the social structure of a group of 110 lactating dairy cows during four one-month periods. Spatial proximity loggers collected data on associations between cows, allowing us to construct social networks. First we demonstrate that proximity loggers can be used to measure relationships between cows; proximity data was significantly positively correlated to affiliative interactions but had no relationship with agonistic interactions. We measured group-level patterns by testing for community structure, centralisation and repeatability of network structure over time. We explored individual-level patterns by measuring social differentiation (heterogeneity of social associations) and assortment of cows in the network by lactation number, breed, gregariousness and milk production. There was no evidence that cows were subdivided into social communities; individuals belonged to a single cluster and networks showed significant centralisation. Repeatability of the social network was low, which may have consequences for animal welfare. Individuals formed differentiated social relationships and there was evidence of positive assortment by traits; cows associated more with conspecifics of similar lactation number in all study periods. There was also positive assortment by breed, gregariousness and milk production in some study periods. There is growing interest in the farming industry in the impact of social factors on production and welfare; this study takes an important step towards understanding social dynamics.DairyCoDepartment for Environment, Food and Rural Affairs (Defra)Biotechnology and Biological Sciences Research Council (BBSRC)University of Exete
Associations Among Androgens, Estrogens, and Natriuretic Peptides in Young Women Observations From the Dallas Heart Study
ObjectivesWe sought to determine if natriuretic peptides are associated with estrogen and androgen status in a population study of young women without known cardiac disease.BackgroundCirculating concentrations of plasma B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are higher in women than in men, and they may be influenced by estrogens and androgens.MethodsCardiac magnetic resonance imaging, dual energy X-ray absorbtiometry, and measurements of BNP, NT-proBNP, follicle-stimulating hormone (FSH), total testosterone, and sex hormone-binding globulin (SHBG), were performed in 682 women (ages 35 to 49 years) participating in the Dallas Heart Study.ResultsIn multivariable analyses adjusting for age, race/ethnicity, body mass index (BMI), serum creatinine, left ventricular mass and left ventricular ejection fraction <55%, menopausal status, and FSH were not associated with BNP and NT-proBNP. In contrast, higher SHBG was associated with higher BNP and NT-proBNP, while the free androgen index and calculated free testosterone were inversely associated with BNP and NT-proBNP (p < 0.0001 for each). Addition of SHBG or any measure of free testosterone to the multivariable models modified the effect of BMI and lean mass, such that measures of body composition were no longer significantly associated with BNP or NT-proBNP.ConclusionsAmong young women, measures of free testosterone were independently and inversely associated with BNP and NT-proBNP. These results suggest that circulating free testosterone, not estradiol, mediates gender differences in natriuretic peptides. In addition, the association between higher BMI and lean body mass with natriuretic peptides may be mediated by testosterone
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