570 research outputs found

    Reduced gravity multibody dynamics testing

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    The Final Report on reduced gravity multibody dynamics testing is presented. Tests were conducted on board the NASA KC-135 RGA in Houston, Texas. The objective was to analyze the effects of large angle rotations on flexible, multi-segmented structures. The flight experiment was conducted to provide data which will be compared to the data gathered from ground tests of the same configurations. The flight and ground tested data will be used to validate the TREETOPS software, software which models dynamic multibody systems, and other multibody codes. The flight experiment consisted of seven complete flights on board the KC-135 RGA during two one-week periods. The first period of testing was 4-9 Apr. 1993. The second period of testing was 13-18 Jun. 1993

    Tourism as a driver of economic development: The Colombian experience

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    The current paper analyzes the importance and potentials of the tourism sector for economic development. It is divided into four major parts. After a short introduction, section two presents some theoretical insights into the topic of economic development. Commenting on the most relevant components of the catching-up theory by Abramovitz (1986) and the structural change theory by Baumol (1967) and others, it could be realized that growth and the accompanying structural changes in the distribution of employment and GDP have their sources in the sector industry. But at the moment of incorporating the demand side explanation of structural change, the service sectors offer growth potentials as well. Furthermore, the basic characteristics and importance of the tourism sector for economic development and employment are emphasized, examining the so-called ?social capabilities? and the innovation potential within the process of economic growth of any nation. A short survey of literature concerning the contribution of this sector to economic growth makes clear that tourism should be considered not just from the perspective of the benefits, but also from the costs associated with it. Section three provides an analysis of the economic impact of tourism in a developing country, namely Colombia, based on time-series analysis and data gathered supported on the ?Tourism Satellite Account? Methodology. Some relevant indicators produced by the World Economic Forum through its ?Travel and Tourism Competitiveness Report?, are also evaluated. Finally, some conclusions are drawn with respect to the potentialities, as well as the challenges identified for the Colombian case

    Tourism as a driver of economic development - the Colombian experience

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    The current paper analyzes the importance and potentials of the tourism sector for economic development. It is divided into four major parts. After a short introduction, section two presents some theoretical insights into the topic of economic development. Commenting on the most relevant components of the catching-up theory by Abramovitz (1986) and the structural change theory by Baumol (1967) and others, it could be realized that growth and the accompanying structural changes in the distribution of employment and GDP have their sources in the sector industry. But at the moment of incorporating the demand side explanation of structural change, the service sectors offer growth potentials as well. Furthermore, the basic characteristics and importance of the tourism sector for economic development and employment are emphasized, examining the so-called ?social capabilities? and the innovation potential within the process of economic growth of any nation. A short survey of literature concerning the contribution of this sector to economic growth makes clear that tourism should be considered not just from the perspective of the benefits, but also from the costs associated with it. Section three provides an analysis of the economic impact of tourism in a developing country, namely Colombia, based on time-series analysis and data gathered supported on the ?Tourism Satellite Account? Methodology. Some relevant indicators produced by the World Economic Forum through its ?Travel and Tourism Competitiveness Report?, are also evaluated. Finally, some conclusions are drawn with respect to the potentialities, as well as the challenges identified for the Colombian case

    Postprandial Glycaemic and Insulinaemic Responses after Consumption of Activated Wheat and Triticale Grain Flakes

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    Funding Information: We thank Vinita Cauce for her invaluable help with data analyses and interpretation. ,e present research leading to these results has received funding from the Norwegian Financial Mechanism 2009–2014 under Project “Innovative approach to hull-less spring cereals and triticale use from human health perspective” (NFI/R/2014/011). Publisher Copyright: © 2019 Laila Meija et al.Increasing evidence shows that whole grain consumption is protective against metabolic disorders. Protective bioactive substances of whole grains include fibre and antioxidants. Activation of grains can increase the amount of phenolic compounds and their bioavailability, but there is little evidence about their effect on glycaemic and insulinemic responses. Therefore, the aim of this study was to investigate glycaemic and insulinemic responses after consumption of flakes made from activated wheat and activated triticale grains. Eighteen healthy subjects (7 men and 11 women) were given activated wheat or activated triticale flakes. As a reference, a standard glucose solution was used. Plasma glucose and serum insulin were measured during 120 minutes. Both, activated wheat and activated triticale flakes, show improved glycaemic profile, inducing a lower and more stable glycaemic response. However, statistically significant differences in insulin response were found only in the group who have taken activated triticale flakes and not in the group who have taken activated wheat flakes. Activated triticale flakes induced lower insulin response in all postprandial phases and a more stable concentration of insulin. Thus, activated triticale flakes could be beneficial for the prevention and treatment of metabolic disorders.publishersversionPeer reviewe

    Solution to papal chemistry challenge

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    Promocijas darbs

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    Nanovadi ir perspektīvi pielietojumiem vides sensoros, nanoelektromehāniskās (NEM) ierīcēs, saules baterijās u.c. Lai šādas ierīces varētu komercializēt, pašlaik tiek strādāts pie to sintēzes uzlabošanas un īpašību izpētes. Lai noteiktu, kuri nanovadi ir perspektīvi pielietošanai NEM slēdžos un sensoros, tika noteiktas to fizikālās īpašības. Darbā tika sintezēti Bi2Se3 nanovadi un izpētītas Bi2Se3, un Ge1-xSnx nanovadu un aerografīta tetrapodu fizikālās īpašības. Tika secināts, ka aerografīts nav piemērots lietošanai NEM slēdžos. Tika realizēti NEM slēdži ar Bi2Se3, Ge1-xSnx un Ge nanovadiem. Tiem tika izpētītas kontakta īpašības un tie tika optimizēti ar oscilējoša lauka palīdzību. Bi2S3 nanovadiem tika pētīta to iespējamā pielietošana vides mitruma sensoros. Atslēgvārdi: nanovadi, sensori, nanoelektromehāniski slēdži, aerografītsNanowires are perspective materials for applications in environment sensors, nanoelectromechanical (NEM) devices, solar batteries, etc. To commercialize these devices, work on optimizing synthesis and determination of their properties is carried out. To determine which nanowires are perspective for use in NEM switches and sensors, their physical properties were determined. Bi2Se3 nanowires were synthesized and the physical properties of Bi2Se3, Ge1-xSnx nanowires and aerographite tetrapods were investigated. NEM switches with Bi2Se3, Ge1-xSnx and Ge nanowires were realized. The contact properties of switches were investigated, and they were optimized by using oscillating electric field. Bi2S3 nanowires were investigated for their potential use in humidity sensors. Keywords: nanowires, sensors, nanoelectromechanical switches, aerographit

    CHEMICAL ALTERATIONS OF HARDWOOD VENEERS DUE TO THERMAL TREATMENT

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    Wood is the most popular building material in the world due to its universal versatility, although it has disadvantages - the difficulty to apply small diameter logs in construction, hygroscopicity and anisotropic swelling and shrinking. To solve these disadvantages, plywood from wood material is produced. Plywood is a material that can solve anisotropy, but it is still biodegradable by rot and stain fungi. Thermal treatment is a methodology that improves the durability of wood. In this paper aspen (Populus tremula L.), poplar (Populus x canadensis Moench) and birch (Betula pendula Roth) were treated by steam (WTT) and vacuum (TERMOVUOTO) devices under 160°C/50 min (birch and aspen), 204°C/2 h, 214°C/2 h, 217°C/3 h, 218°C/30 min (birch and poplar). Chemical changes in treated veneers were investigated by ATR-FTIR (Attenuated Total Reflection Fourier Transform Infrared Spectroscopy) in a range 2000 cm-1 – 800 cm-1. ATR-FTIR is a non-destructive methodology, which is important during manufacturing process quality control. Untreated poplar wood and aspen wood had similar ATR-FTIR spectra because both species belong to Populus genus. Untreated birch wood had higher absorption intensity peak at 1740 cm-1, which indicates the C=O bond stretching in the carboxyl group depicting more acetyl groups in birch wood than in aspen/poplar. According to spectral data, birch wood, treated in TERMOVUOTO process at 200°C for 2 hours is chemically almost identical to untreated one. WTT process causes the most significant changes in the chemistry of both in aspen and birch. Therefore, regime 160°C/50 min in water vapour is more aggressive than treatments at higher temperatures and under reduced pressure. It is expected that plywood produced from WTT treated veneers will have reduced strength in comparison with TERMOVUOTO process produced ones
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