391 research outputs found

    Are the therapeutic strategies in anorexia of ageing effective on nutritional status? A systematic review with meta-analysis

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    BACKGROUND: Anorexia of ageing (AA) may be considered as a risk factor for frailty and has an important impact on quality of life, morbidity and mortality. METHODS: A systematic review and a meta-analysis were performed to summarise the results from several trials on the effectiveness of treatments in AA, as associated with depression, sensory impairment of taste and smell, decreased appetite or early satiety, and disability. Eligible studies were required to report baseline and follow-up values, the mean change (∆-change) from baseline, and/or the mean difference among intervention groups versus control group, concerning food intake (kcal/daily) and/or nutritional outcomes, such as body weight, body mass index, albumin and Mini Nutritional Assessment. RESULTS: The systematic review included 20 papers based on different therapeutic approaches concerning food intake and/or nutritional outcomes. The results of the meta-analysis indicate that the interventions for AA have an important impact on body weight [+1.59 kg; 95% confidence interval (CI) = 1.48-+1.71 kg; P < 0.001) and on energy intake (+56.09 kcal; 95% CI = -54.05 to +166.25 kcal; P = 0.32). Regarding secondary outcomes, it was not possible to meta-analyse the limited amount of data availab le. CONCLUSIONS: The different variants of AA need to be defined because diverse therapeutic approaches are available. A more precise definition of the functional impairments associated with AA may allow a more correct decision about the most appropriate therapy to be prescribed. Moreover, this may allow for a more effective performance of the different therapeutic approaches once they are better targeted to the different scenarios of AA

    One-step volumetric additive manufacturing of complex polymer structures.

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    Two limitations of additive manufacturing methods that arise from layer-based fabrication are slow speed and geometric constraints (which include poor surface quality). Both limitations are overcome in the work reported here, introducing a new volumetric additive fabrication paradigm that produces photopolymer structures with complex nonperiodic three-dimensional geometries on a time scale of seconds. We implement this approach using holographic patterning of light fields, demonstrate the fabrication of a variety of structures, and study the properties of the light patterns and photosensitive resins required for this fabrication approach. The results indicate that low-absorbing resins containing ~0.1% photoinitiator, illuminated at modest powers (~10 to 100 mW), may be successfully used to build full structures in ~1 to 10 s

    Polytope Sector-Based Synthesis and Analysis of Microstructural Architectures With Tunable Thermal Conductivity and Expansion

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    The aim of this paper is to (1) introduce an approach, called polytope sector-based synthesis (PSS), for synthesizing 2D or 3D microstructural architectures that exhibit a desired bulk-property directionality (e.g., isotropic, cubic, orthotropic, etc.), and (2) provide general analytical methods that can be used to rapidly optimize the geometric parameters of these architectures such that they achieve a desired combination of bulk thermal conductivity and thermal expansion properties. Although the methods introduced can be applied to general beam-based microstructural architectures, we demonstrate their utility in the context of an architecture that can be tuned to achieve a large range of extreme thermal expansion coefficients—positive, zero, and negative. The material-property-combination region that can be achieved by this architecture is determined within an Ashby-material-property plot of thermal expansion versus thermal conductivity using the analytical methods introduced. These methods are verified using finite-element analysis (FEA) and both 2D and 3D versions of the design have been fabricated using projection microstereolithography.United States. Defense Advanced Research Projects Agency. Materials with Controlled Microstructural Architectures Progra

    Is vitamin D-fortified yogurt a value-added strategy for improving human health? A systematic review and meta-analysis of randomized trials

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    Yogurt is a good source of probiotics, calcium, and proteins, but its content of vitamin D is low. Therefore, yogurt could be a good choice for vitamin D fortification to improve the positive health outcomes associated with its consumption. The primary aim of this systematic review and meta-analysis was to investigate the effect of vitamin D-fortified yogurt compared with plain yogurt on levels of serum 25-hydroxy vitamin D (25OHD). The secondary aim was to evaluate the effect of fortified yogurt on parathyroid hormone, anthropometric parameters, blood pressure, glucose metabolism, and lipid profile. We searched PubMed, Scopus, and Google Scholar for eligible studies; that is, randomized controlled trials (RCT) that compared vitamin D-fortified yogurt with control treatment without any additional supplement. Random-effects models were used to estimate pooled effect sizes and 95% confidence intervals. Findings from 9 RCT (n = 665 participants) that lasted from 8 to 16 wk are summarized in this review. The meta-analyzed mean differences for random effects showed that vitamin D-fortified yogurt (from 400 to 2,000 IU) increased serum 25OHD by 31.00 nmol/L. In addition, vitamin D-fortified yogurt decreased parathyroid hormone by 15.47 ng/L, body weight by 0.92 kg, waist circumference by 2.01 cm, HOMA-IR by 2.18 mass units, fasting serum glucose by 22.54 mg/dL, total cholesterol by 13.38 mg/dL, and triglycerides by 30.12 mg/dL compared with the controlled treatments. No publication bias was identified. Considerable between-study heterogeneity was observed for most outcomes. Vitamin D-fortified yogurt may be beneficial in improving serum 25OHD, lipid profile, glucose metabolism, and anthropometric parameters and decreasing parathyroid hormone level in pregnant women and adult and elderly subjects with or without diabetes, prediabetes, or metabolic syndrome

    Aerodynamic performance measurements of a fully scaled, film-coated, turbine stage

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1999.Includes bibliographical references (p. 147-148).The MIT Blowdown Turbine short duration test facility was used to experimentally measure the aerodynamic performance of a film-cooled turbine stage. Turbine torque, speed, mass flow, temperature, and pressure were measured and used to calculate efficiency. Pressure ratio, corrected speed, and coolant mass flow were varied parametrically over a range of conditions and compared to a baseline. No distinct trend was seen in the pressure ratio tests. Efficiency increased approximately 2.2% with a corrected speed increase of 20%. This trend is a result of a corresponding decrease in blade loading. An efficiency decrease of 2% was shown for a two-fold increase in coolant mass flow. A preliminary comparison to a previous uncooled test series showed a 2% decrease in efficiency with a 12% coolant-to-mainstream mass flow ratio. To complete these tests, an uncooled turbine configuration was modified to a film-cooled configuration. A solid blade and nozzle guide vane set was machined via electro-discharge machining, laser drilling, and laser welding to provide film-cooling holes and manifold channels. The effective area (CdA) of the film-cooling holes was measured and part-to-part variations quantified. A coolant feed system was constructed to provide coolant flow to the turbine. Flow to the rotor blades, nozzle guide vanes, and tip casing was metered and controlled independently. Thick walled, squared edged, choked orifices were used. A set of experiments were performed to show that supersaturated coolant flow could be adequately controlled by this method.by Christopher M. Spadaccini.S.M

    Lightweight Mechanical Metamaterials with Tunable Negative Thermal Expansion

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    Ice floating on water is a great manifestation of negative thermal expansion (NTE) in nature. The limited examples of natural materials possessing NTE have stimulated research on engineered structures. Previous studies on NTE structures were mostly focused on theoretical design with limited experimental demonstration in two-dimensional planar geometries. In this work, aided with multimaterial projection microstereolithography, we experimentally fabricate lightweight multimaterial lattices that exhibit significant negative thermal expansion in three directions and over a temperature range of 170 degrees. Such NTE is induced by the structural interaction of material components with distinct thermal expansion coefficients. The NTE can be tuned over a large range by varying the thermal expansion coefficient difference between constituent beams and geometrical arrangements. Our experimental results match qualitatively with a simple scaling law and quantitatively with computational models.United States. Defense Advanced Research Projects Agency. Materials with Controlled Microstructural Architectures ProgramLawrence Livermore National Laboratory (Award DE-AC52-07NA27344 (LLNL-JRNL-697779))SUTD-MIT Postdoctoral Progra

    Is a combination of melatonin and amino acids useful to sarcopenic elderly patients? A randomized trial

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    This study evaluated the effectiveness of a 4-week intervention of melatonin and essential aminoacid supplementation on body composition, protein metabolism, strength and inflammation in 159 elderly sarcopenic patients (42/117, men/women), assigned to four groups: isocaloric placebo (P, n = 44), melatonin (M, 1 mg/daily, n = 42), essential amino acids (eAA 4 g/daily, n = 40) or eAA plus melatonin (eAAM, 4 g eAA and 1 mg melatonin/daily, n = 30). Data from body composition (dual X-ray absortiometry (DXA)), strength (handgrip test) and biochemical parameters for the assessment of protein metabolism (albumin) and inflammation (CRP) were collected at baseline and after the 4-week intervention. Compared with P and M, supplementation with eAA plus M increased total fat-free mass (vs. P: +2190 g; p < 0.01; vs. M: +2107 g; p < 0.05). M alone lowered albumin levels (vs. P: -0.39 g; p < 0.01; vs. eAA: -0.47 g; p < 0.01). This data on albumin was confirmed by within-group analysis (M -0.44g; p < 0.001; eAAM: -0.34 p < 0.05). M and eAA seemed to lower the percentage of gynoid fat (p < 0.05) and android fat (p < 0.01). No significant changes in inflammation or strength were reported. A 4-week intervention with eAA plus M together may be effective in enhancing fat-free-mass compared to M and P but not versus eAA. M alone demonstrates a negative effect on albumin level
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