98 research outputs found

    Mach's Principle and the Origin of Inertia

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    The current status of Mach's principle is discussed within the context of general relativity. The inertial properties of a particle are determined by its mass and spin, since these characterize the irreducible unitary representations of the inhomogeneous Lorentz group. The origin of the inertia of mass and intrinsic spin are discussed and the inertia of intrinsic spin is studied via the coupling of intrinsic spin with rotation. The implications of spin-rotation coupling and the possibility of history dependence and nonlocality in relativistic physics are briefly mentioned.Comment: 14 pages. Dedicated to Carl Brans in honor of his 80th birthday. To appear in the Brans Festschrift; v2: typo corrected, published in: At the Frontier of Spacetime, edited by T. Asselmeyer-Maluga (Springer, 2016), Chapter 10, pp. 177-18

    Innovation and growth in the UK pharmaceuticals: the case of product and marketing introductions

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    New drug introductions are key to growth for pharmaceutical firms. However, not all innovations are the same and they may have differential effects that vary by firm size. We use quarterly sales data on UK pharmaceuticals in a dynamic panel model to estimate the impact of product (new drugs) and marketing (additional pack varieties) innovations within a therapeutic class on a firm’s business unit growth. We find that product innovations lead to substantial growth in both the short and long run, whereas a new pack variety only produces short-term effects. The strategies are substitutes but the marginal effects are larger for product innovations relative to additional packs, and the effects are larger for smaller business units. Nonetheless, pack introductions offer a viable short-term growth strategy, especially for small- and medium-sized businesses

    More resistant tendons obtained from the association of Heteropterys aphrodisiaca and endurance training

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    <p>Abstract</p> <p>Background</p> <p>Popular Brazilian medicine uses <it>Heteropterys aphrodisiaca </it>infusion as a tonic or stimulant, for the treatment of nervous debility and breakdown and for muscle and bone weakness. This study investigated the effects of <it>Heteropterys aphrodisiaca </it>infusion on the tendon properties and extracellular matrix of rats under endurance training.</p> <p>Methods</p> <p>Wistar rats were grouped as follows: CS- control sedentary, HS- <it>H. aphrodisiaca </it>sedentary, CT-control trained, HT- <it>H. aphrodisiaca </it>trained. The training protocol consisted in running on a motorized treadmill, five times a week, with weekly increase in treadmill speed and duration. Control groups received water while the HS and HT groups received <it>H. aphrodisiaca </it>infusion, daily, by gavage for the 8 weeks of training. Achilles tendons were frozen for biochemical and biomechanical analysis or preserved in Karnovsky's fixative, then processed for histomorphological analysis with light microscopy.</p> <p>Results</p> <p>Biomechanical analysis showed significant increase in maximum load, maximum stress, modulus of elasticity and stiffness of the HT animals' tendons. The metalloproteinase-2 activity was reduced in the HT group. The compression region of HT animals' tendons had a stronger and more intense metachromasy, which suggests an increase in glycosaminoglycan concentration in this region of the tendon. The most intense birefringence was observed in both compression and tension regions of HT animals' tendons, which may indicate a higher organizational level of collagen bundles. The hydroxyproline content increased in the HT group.</p> <p>Conclusions</p> <p>The association of endurance training with <it>H. aphrodisiaca </it>resulted in more organized collagen bundles and more resistant tendons to support higher loads from intense muscle contraction. Despite the clear anabolic effects of <it>Heteropterys aphrodisiaca </it>and the endurance exercise association, no side effects were observed, such as those found for synthetic anabolic androgenic steroids.</p

    Toward nanofluids of ultra-high thermal conductivity

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    The assessment of proposed origins for thermal conductivity enhancement in nanofluids signifies the importance of particle morphology and coupled transport in determining nanofluid heat conduction and thermal conductivity. The success of developing nanofluids of superior conductivity depends thus very much on our understanding and manipulation of the morphology and the coupled transport. Nanofluids with conductivity of upper Hashin-Shtrikman (H-S) bound can be obtained by manipulating particles into an interconnected configuration that disperses the base fluid and thus significantly enhancing the particle-fluid interfacial energy transport. Nanofluids with conductivity higher than the upper H-S bound could also be developed by manipulating the coupled transport among various transport processes, and thus the nature of heat conduction in nanofluids. While the direct contributions of ordered liquid layer and particle Brownian motion to the nanofluid conductivity are negligible, their indirect effects can be significant via their influence on the particle morphology and/or the coupled transport

    Mitochondrial function as a determinant of life span

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    Average human life expectancy has progressively increased over many decades largely due to improvements in nutrition, vaccination, antimicrobial agents, and effective treatment/prevention of cardiovascular disease, cancer, etc. Maximal life span, in contrast, has changed very little. Caloric restriction (CR) increases maximal life span in many species, in concert with improvements in mitochondrial function. These effects have yet to be demonstrated in humans, and the duration and level of CR required to extend life span in animals is not realistic in humans. Physical activity (voluntary exercise) continues to hold much promise for increasing healthy life expectancy in humans, but remains to show any impact to increase maximal life span. However, longevity in Caenorhabditis elegans is related to activity levels, possibly through maintenance of mitochondrial function throughout the life span. In humans, we reported a progressive decline in muscle mitochondrial DNA abundance and protein synthesis with age. Other investigators also noted age-related declines in muscle mitochondrial function, which are related to peak oxygen uptake. Long-term aerobic exercise largely prevented age-related declines in mitochondrial DNA abundance and function in humans and may increase spontaneous activity levels in mice. Notwithstanding, the impact of aerobic exercise and activity levels on maximal life span is uncertain. It is proposed that age-related declines in mitochondrial content and function not only affect physical function, but also play a major role in regulation of life span. Regular aerobic exercise and prevention of adiposity by healthy diet may increase healthy life expectancy and prolong life span through beneficial effects at the level of the mitochondrion

    Ceremonial plant consumption at Middle Bronze Age Büklükale, Kırıkkale Province, central Turkey

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    A shaft-like room at the Middle Bronze Age site of Büklükale in central Turkey preserved a rich archaeobotanical assemblage of charred and mineralised plant remains, dominated by fruits, spices and nuts mixed with probable bread and wood charcoals. The remains were recovered in association with numerous ceramic vessels, jewellery and exotic artefacts. We combine identification and analysis of the seeds and wood charcoals contained in this deposit with studies of Old Assyrian and Hittite textual records to investigate the circumstances of the assemblage’s formation and its significance for further understanding trade and plant consumption in Bronze Age Anatolia. We present the earliest archaeobotanical example in the region of rare and exotic plant species being consumed in the context of one or more social gatherings, including those possibly linked to ceremonial or ritual events. This offers new insights into the role of plants in the economic and social life of the southwest Asian Bronze Age, as well as the role of commensality and feasting in early states

    Non-ionic Thermoresponsive Polymers in Water

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    Screening of fatty acid composition in Nitzschia sp.

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    Introduction: the main target of this study was to compare the effects of nitrogen limitation and light intensities on cell growth, lipid content and fatty acid profile of Nitzschia sp.Methods: F/2  medium and N-free F/2  medium were both tested at two different light intensities of 11 and 56 ?E?m???2?s???1 in the internal loop air-lift photobioreactor for Nitzschia sp.Results: the presence of nitrogen led to more cells grown efficiently. Furthermore, the increase in chlorophyll content went parallel to the increase in dry weight. the most abundant saturated and monounsaturated fatty acids were pentadecanoic acid (C15:0) and palmitoleic acid (C16:1) which constituted 17%–42% and 15%–48% of total fatty acids for all growth conditions, respectively. It was recorded that palmitoleic acid was present at higher concentrations than palmitic acid.Discussion and conclusion: the noteworthy finding was that the lipid content increased with increasing the growth rate of Nitzschia sp. under phototrophic conditionsGi?ri?ş ve amaç: Bu çalışmadaki ana hedef Nitzschia sp. türünün büyüme hızı, lipit içeriği ve yağ asidi profili üzerine nitrojen kısıtlamasının ve ışık şiddetinin etkilerinin karşılaştırılmasıdı
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