3,471 research outputs found

    A robust design methodology suitable for application to one-off products

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    Robust design is an activity of fundamental importance when designing large, complex, one-off engineering products. Work is described which is concerned with the application of the theory of design of experiments and stochastic optimization methods to explore and optimize at the concept design stage. The discussion begins with a description of state-of-the-art stochastic techniques and their application to robust design. The content then focuses on a generic methodology which is capable of manipulating design algorithms that can be used to describe a design concept. An example is presented, demonstrating the use of the system for the robust design of a catamaran with respect to seakeeping

    Comparative aspects of phytase and xylanase effects on performance, mineral digestibility, and ileal phytate degradation in broilers and turkeys

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    Two experiments were performed, using broilers or turkeys, each utilizing a 3 × 2 factorial arrangement, to compare their response to phytase and xylanase supplementation with growth performance, nutrient digestibility, and ileal phytate degradation as response criteria. For both experiments, 960 Ross 308 or 960 BUT 10 (0-day-old) birds were allocated to 6 treatments: (1) control diet, containing phytase at 500 FTU/kg; (2) the control diet with xylanase (16,000 BXU/kg); (3) the control diet supplemented on top with phytase (1,500 FTU/kg); (4) diet supplemented with 1,500 FTU/kg phytase and xylanase (16,000 BXU/kg); (5) the control diet supplemented with phytase (3,000 FTU/kg); and (6) diet supplemented with 3,000 FTU/kg phytase and xylanase (16,000 BXU/kg). Each treatment had 8 replicates of 20 birds each. Water and diets based on wheat, soybean meal, oilseed rape meal, and barley were available ad libitum. Body weight gain and feed intake were measured from 0 to 28 D, and feed conversion ratio (FCR) corrected for mortality was calculated. Ileal digestibility for dry matter and minerals on day 7 and 28 were analyzed in addition to levels of inositol phosphate esters (InsP6-3) and myo-inositol. Statistical comparisons were performed using ANOVA. Xylanase supplementation improved 28D FCR in broilers and turkeys. Increasing doses of phytase reduced FI and improved FCR only in broilers. In broilers, the age × phytase interaction for phosphorous digestibility showed that increasing phytase dose was more visible on day 7, than on day 28. Mineral digestibility was lower in 28-day-old turkey compared with 7-day-old turkey. InsP6 disappearance increased with increasing phytase levels in both species, with lower levels analyzed in turkeys. InsP6 disappearance was greater in younger turkeys (day 7 compared with day 28). In conclusion, although broilers and turkeys shared several similarities in their growth and nutrient utilization responses, the outcomes of the 2 trials also differed in many aspects. Whether this is because of difference in diets (InsP or Ca level) or differences between species needs further investigation

    Developing a model to estimate the potential impact of municipal investment on city health

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    This article summarizes a process which exemplifies the potential impact of municipal investment on the burden of cardiovascular disease (CVD) in city populations. We report on Developing an evidence-based approach to city public health planning and investment in Europe (DECiPHEr), a project part funded by the European Union. It had twin objectives: first, to develop and validate a vocational educational training package for policy makers and political decision takers; second, to use this opportunity to iterate a robust and user-friendly investment tool for maximizing the public health impact of 'mainstream' municipal policies, programs and investments. There were seven stages in the development process shared by an academic team from Sheffield Hallam University and partners from four cities drawn from the WHO European Healthy Cities Network. There were five iterations of the model resulting from this process. The initial focus was CVD as the biggest cause of death and disability in Europe. Our original prototype 'cost offset' model was confined to proximal determinants of CVD, utilizing modified 'Framingham' equations to estimate the impact of population level cardiovascular risk factor reduction on future demand for acute hospital admissions. The DECiPHEr iterations first extended the scope of the model to distal determinants and then focused progressively on practical interventions. Six key domains of local influence on population health were introduced into the model by the development process: education, housing, environment, public health, economy and security. Deploying a realist synthesis methodology, the model then connected distal with proximal determinants of CVD. Existing scientific evidence and cities' experiential knowledge were 'plugged-in' or 'triangulated' to elaborate the causal pathways from domain interventions to public health impacts. A key product is an enhanced version of the cost offset model, named Sheffield Health Effectiveness Framework Tool, incorporating both proximal and distal determinants in estimating the cost benefits of domain interventions. A key message is that the insights of the policy community are essential in developing and then utilising such a predictive tool

    Affective symptoms and risk of progression to mild cognitive impairment or dementia in subjective cognitive decline: A systematic review and meta-analysis

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    Aims: To systematically review the literature on outcomes for individuals with subjective cognitive decline (SCD) with concurrent affective symptoms. To conduct a meta-analysis to establish whether either higher depressive symptoms or higher levels of anxiety increased the risk of progression SCD to mild cognitive impairment (MCI) or dementia. / Methods: Five databases were searched from inception to February 2021 for longitudinal studies of older adults with SCD, reporting depressive and anxiety symptoms at baseline and risk of MCI or dementia at follow-up. Data were extracted and pooled using a random-effects meta-analysis. / Results: Twelve studies were identified. Pooled effect sizes indicated higher depressive symptoms did not increase risk of clinical progression to either MCI (RR = 0.98; 95% CI: 0.75 – 1.26) or dementia (RR = 0.69; 95% CI: 0.27 – 1.79). However, presence of anxiety or SCD-related worry did significantly increase risk of progression from subjective to objective cognitive impairment by 40% (RR = 1.40; 95% CI:1.20 – 1.63). / Conclusions: Affective symptoms in the form of anxiety, but not depressive symptoms, increase the risk of progression to objective cognitive impairment in individuals with SCD. Further research should focus on establishing whether psychological interventions aimed at reducing anxiety and worry also reduce the risk of clinical progression

    The Putative Role of Resveratrol in SIRT-1 Mediated Modulation of the Vitamin D Pathway

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    The nuclear vitamin D receptor (VDR) modulates gene transcription in 1,25-dihydroxyvitamin D (1,25D) target tissues such as kidney, colon, and bone. The 1,25D hormone is derived from vitamin D in the skin or from the diet, and binds to and activates the VDR. We have previously shown that resveratrol, an antioxidant found in the skin of red grapes, has the ability to activate the VDR signaling pathway. Moreover, cells treated with both resveratrol and 1,25D resulted in an additive or even synergistic stimulation of VDR-mediated transcription compared to cells treated with 1,25D alone. Based on these initial results, experiments were designed to test the significance of mutations in the hormone-binding domain of VDR. Identical hormone treatments were applied to “wild-type” (non-mutated) and single point VDR mutations. 1,25D displayed a significant drop in activity caused by these mutations, while the ability of resveratrol to activate VDR was only modestly attenuated. One possible interpretation of these results is that resveratrol may affect VDR activity indirectly, perhaps via the ability of resveratrol to activate SIRT1, an enzyme which has been shown to deacetylate (and thereby activate) other nuclear receptors such as the liver X receptor (LXR). In support of this hypothesis, radiolabeled 1,25D displacement assays revealed an increase in bound radiolabeled 1,25D only in the presence of resveratrol, suggesting that direct binding of resveratrol to VDR is unlikely. Additionally, we observed increased transcriptional activity in response to resveratrol in a subset of other nuclear receptors, including the liver X receptor (LXR), which is closely related to VDR and is known to be deacetylated by SIRT1. Finally, we tested receptor-mediated transcriptional activity in a system containing VDR in the absence and presence of overexpressed SIRT1. Transcriptional activity was higher in cells expressing SIRT1, and synergistic activity of 1,25D combined with resveratrol was observed. We are currently conducting additional experiments employing the VDR/SIRT1 assay in multiple cellular contexts. In conclusion, this study elucidates, for the first time, a potential novel pathway for crosstalk between two nutritionally derived lipids, vitamin D and resveratrol

    Discussion of Recent Decisions

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    Comparison of Human Milk Fatty Acid Composition of Women From Cambodia and Australia

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    Human milk is a rich source of omega-3 long-chain polyunsaturated fatty acids, which are postulated to be important for brain development. There is a lack of data on the human milk fatty acid composition of Cambodian women compared with data from Western women. The aim of this study was to determine the human milk fatty acid composition of women living in Cambodia and compare it with that of women living in Australia. Human milk samples from Cambodian (n = 67) and Australian (n = 200) mothers were collected at 3 to 4 months postpartum. Fatty acid composition was analyzed using capillary gas chromatography followed by Folch extraction with chloroform/methanol (2:1 v/v), and fat content was measured gravimetrically. Compared with Australian participants, human milk from Cambodian participants contained a significantly lower level of total fat (2.90 vs. 3.45 g/dL, p = .028), lower percentages of linoleic acid (9.30% vs. 10.66%, p < .0001) and α-linolenic acid (0.42% vs. 0.95%, p < .0001), but higher percentages of arachidonic acid (0.68% vs. 0.38%, p < .0001) and docosahexaenoic acid (0.40% vs. 0.23%, p < .0001). Differences in human milk fatty acid composition between Cambodian and Australian participants may be explained by differences in the dietary patterns between the two populations.Chang Gao, Ge Liu, Kyly C. Whitfield, Hou Kroeun, Timothy J. Green, Robert A. Gibson, Maria Makrides, and Shao J. Zho

    The contribution of diet and genotype to iron status in women:a classical twin study

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    This is the first published report examining the combined effect of diet and genotype on body iron content using a classical twin study design. The aim of this study was to determine the relative contribution of genetic and environmental factors in determining iron status. The population was comprised of 200 BMI- and age-matched pairs of MZ and DZ healthy twins, characterised for habitual diet and 15 iron-related candidate genetic markers. Variance components analysis demonstrated that the heritability of serum ferritin (SF) and soluble transferrin receptor was 44% and 54% respectively. Measured single nucleotide polymorphisms explained 5% and selected dietary factors 6% of the variance in iron status; there was a negative association between calcium intake and body iron (p = 0.02) and SF (p = 0.04)
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