2,164 research outputs found

    Semi-2-interpenetrating networks of high temperature systems

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    A semi-2-interpenetrating network of improved qualities which is prepared by combining a linear polymer and a cross-linkable oligomer having identical repeating units is developed. Polymers have been combined in the past into interpenetrating networks in order to gain useful properties from the combination of materials. However, previous semi-interpenetrating networks have only been formed using polymers having different repeating units. This method provides a semi-2-interpenetrating network of improved strength, adhesion, and processability

    On the evolution of snow roughness during snow fall

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    The deposition and attachment mechanism of settling snow crystals during snowfall dictates the very initial structure of ice within a natural snowpack. In this letter we apply ballistic deposition as a simple model to study the structural evolution of the growing surface of a snowpack during its formation. The roughness of the snow surface is predicted from the behaviour of the time dependent height correlation function. The predictions are verified by simple measurements of the growing snow surface based on digital photography during snowfall. The measurements are in agreement with the theoretical predictions within the limitations of the model which are discussed. The application of ballistic deposition type growth models illuminates structural aspects of snow from the perspective of formation which has been ignored so far. Implications of this type of growth on the aerodynamic roughness length, density, and the density correlation function of new snow are discusse

    Micrometeorological processes driving snow ablation in an Alpine catchment

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    Mountain snow covers typically become patchy over the course of a melting season. The snow pattern during melt is mainly governed by the end of winter snow depth distribution and the local energy balance. The objective of this study is to investigate micrometeorological processes driving snow ablation in an Alpine catchment. For this purpose we combine a meteorological model (ARPS) with a fully distributed energy balance model (Alpine3D). Turbulent fluxes above melting snow are further investigated by using data from eddy-correlation systems. We compare modelled snow ablation to measured ablation rates as obtained from a series of Terrestrial Laser Scanning campaigns covering a complete ablation season. The measured ablation rates indicate that the advection of sensible heat causes locally increased ablation rates at the upwind edges of the snow patches. The effect, however, appears to be active over rather short distances except for very strong wind conditions. Neglecting this effect, the model is able to capture the mean ablation rates for early ablation periods but strongly overestimates snow ablation once the fraction of snow coverage is below a critical value. While radiation dominates snow ablation early in the season, the turbulent flux contribution becomes important late in the season. Simulation results indicate that the air temperatures appear to overestimate the local air temperature above snow patches once the snow coverage is below a critical value. Measured turbulent fluxes support these findings by suggesting a stable internal boundary layer close to the snow surface causing a strong decrease of the sensible heat flux towards the snow cover. Thus, the existence of a stable internal boundary layer above a patchy snow cover exerts a dominant control on the timing and magnitude of snow ablation for patchy snow covers.<br/

    Airline consolidation in Europe : small European airlines’ chances of survival amid industry consolidation, and the proactive M&A auction as a strategic way forward

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    The European airline industry is experiencing a trend towards consolidation, and many carriers are contesting in a highly competitive environment. From 2011-2015, the number of scheduled airlines operating within Europe declined by over 70, and the growing influence of large players such as the Lufthansa Group or the IAG Holding challenges small airlines in their economic viability. Consequently, small firms must find new strategic solutions to secure their continuing existence. The aim of this study was to clarify the chances of survival for small airlines, and if selling the company proactively through an M&A auction could be a beneficial solution to the consolidation trend. Therein, the focus lies in maximizing the transaction price and ensuring the continuity of the brand. Additionally, the study intended to identify key criteria and stumbling blocks for small airlines considering to follow such a strategy

    Emergency department visits for non-life-threatening conditions : evolution over 13 years in a Swiss urban teaching hospital

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    INTRODUCTION: A large proportion of visits to our Emergency Department (ED) are for non-life-threatening conditions. We investigated whether patients' characteristics and reasons for consultation had changed over 13 years. METHODS: Consecutive adult patients with non-life-threatening conditions at triage were included in the spring of 2000 and in the summer of 2013. In both years patients completed a similar questionnaire, which addressed their reasons for consultation and any previous consultation with a general practitioner (GP). RESULTS: We included 581 patients in 2013 vs 516 in 2000, with a mean age of 44.5 years vs 46.4 years (p=0.128). Of these patients, 54.0% vs 57.0% were male (p=0.329), 55.5% vs 58.7% were Swiss (p=0.282), 76.4% were registered with a GP in both periods, but self-referral increased from 52.0% to 68.8% (p&lt;0.001); 57.7% vs., 58.3% consulted during out-of- hours (p=0.821). Trauma-related visits decreased from 34.2% to 23.7% (p&lt;0.001). Consultations within 12 hours of onset of symptoms dropped from 54.5% to 30.9%, and delays of ≥1 week increased from 14.3% to 26.9% (p&lt;0.001). The primary motive for self-referral remained unawareness of an alternative, followed in 2013 by dissatisfaction with the GP's treatment or appointment. Patients who believed that their health problem would not require hospitalisation increased from 52.8% to 74.2% and those who were actually hospitalised decreased from 24.9% to 13.9% (all p&lt;0.001). CONCLUSION: The number of visits for non-life-threatening consultations continue to increase. Our ED is used by a large proportion of patients as a convenient alternative source of primary care

    Foliar Fertilization of Soybeans

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    Research reported by Iowa State University during the winter of 1975-76 suggested that a means of increasing soybean yields by use of a specific foliar fertilizer had been demonstrated (1976). Theory proposed to explain the reported responses was as follows: Up to the seed filling period in soybean growth, soybean roots and activity of nitrogen-fixing bacteria contained in root nodules are capable of supplying the necessary nutrients to meet the plants demands. However, as seed filling begins root growth stops and nodule activity declines. This results in nutrients being redistributed from leaves to seeds and a reduction in rate of photosynthesis. Consequently, studies were conducted to evaluate methods of foliar fertilization in an attempt to maintain photosynthetic rate and nutrient supply during seed filling, the objective being to increase yields

    The Influence of Soil Temperature on Soybean Seed Emergence

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    The best way to obtain adequate soybean stands is to plant high quality seed in an optimum soil environment. But this year many farmers may not be able to obtain enough high quality soybean seed and some acreage may be planted with seed of lower than normal quality. Thus it will be even more important to have an optimum soil environment

    Foliar Fertilization of Soybeans - 1977

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    Field investigations on the effect of foliar fertilization were continued on soybeans during 1977. Results from our 1976 studies have previously been published. In 1976 we tested a material produced by TVA. We used the same TVA-material in 1977 and in addition, included a commercially available product (Foliantm, manufactured by Allied Chemical Corporation)
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