155 research outputs found

    Modelling the effects of land-use and land-cover change on water availability in the Jordan River region

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    Within the GLOWA Jordan River project, a first-time overview of the current and possible future land and water conditions of a major part of the Eastern Mediterranean region (ca. 100 000 km<sup>2</sup>) is given. First, we applied the hydrological model TRAIN to simulate current water availability (runoff and groundwater recharge) and irrigation water demand on a 1 km×1 km spatial resolution. The results demonstrate the scarcity of water resources in the study region, with extremely low values of water availability in the semi-arid and arid parts. Then, a set of four divergent scenarios on the future of water has been developed using a stakeholder driven approach. Relevant drivers for land-use/land-cover change were fed into the LandSHIFT.R model to produce land-use and land-cover maps for the different scenarios. These maps were used as input to TRAIN in order to generate scenarios of water availability and irrigation water demand for the region. For this study, two intermediate scenarios were selected, with projected developments ranging between optimistic and pessimistic futures (with regard to social and economic conditions in the region). Given that climate conditions remain unchanged, the simulations show both increases and decreases in water availability, depending on the future pattern of natural and agricultural vegetation and the related dominance of hydrological processes

    Determination of inherent dissolution performance of drug substances

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    The dissolution behavior of novel active pharmaceutical ingredients (API) is a crucial parameter in drug formulation since it frequently affects the drug release. Generally, a distinction is made between surface-reaction- and diffusion-controlled drug release. Therefore, dissolution studies such as the intrinsic dissolution test defined in the pharmacopeia have been performed for many years. In order to overcome the disadvantages of the common intrinsic dissolution test, a new experimental setup was developed within this study. Specifically, a flow channel was designed and tested for measuring the mass transfer from a flat, solid surface dissolving into a fluid flowing over the surface with well-defined flow conditions. A mathematical model was developed that distinguishes between surface-reaction- and diffusion-limited drug release based on experimental data. Three different drugs—benzocaine, theophylline and griseofulvin—were used to investigate the mass flux during dissolution due to surface reaction, diffusion and convection kinetics. This new technique shows potential to be a valuable tool for the identification of formulation strategies

    Spontaneous annihilation of high-density matter in the electroweak theory

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    In the presence of fermionic matter the topologically distinct vacua of the standard model are metastable and can decay by tunneling through the sphaleron barrier. This process annihilates one fermion per doublet due to the anomalous non-conservation of baryon and lepton currents and is accompanied by a production of gauge and Higgs bosons. We present a numerical method to obtain local bounce solutions which minimize the Euclidean action in the space of all configurations connecting two adjacent topological sectors. These solutions determine the decay rate and the configuration of the fields after the tunneling. We also follow the real time evolution of this configuration and analyze the spectrum of the created bosons. If the matter density exceeds some critical value, the exponentially suppressed tunneling triggers off an avalanche producing an enormous amount of bosons.Comment: 38 pages, 6 Postscript figure

    Exploring future agricultural development and biodiversity in Uganda, Rwanda and Burundi: a spatially explicit scenario-based assessment

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    Competition for land is increasing as a consequence of the growing demands for food and other commodities and the need to conserve biodiversity and ecosystem services. Land conversion and the intensification of current agricultural systems continues to lead to a loss of biodiversity and trade-offs among ecosystem functions. Decision-makers need to understand these trade-offs in order to better balance different demands on land and resources. There is an urgent need for spatially explicit information and analyses on the effects of different trajectories of human-induced landscape change in biodiversity and ecosystem services. We assess the potential implications of a set of plausible socio-economic and climate scenarios for agricultural production and demand and model-associated land use and land cover changes between 2005 and 2050 to assess potential impacts on biodiversity in Uganda, Rwanda and Burundi. We show that different future socio-economic scenarios are consistent in their projections of areas of high agricultural development leading to similar spatial patterns of habitat and biodiversity loss. Yet, we also show that without protected areas, biodiversity losses are higher and that expanding protected areas to include other important biodiversity areas can help reduce biodiversity losses in all three countries. These results highlight the need for effective protection and the potential benefits of expanding the protected area network while meeting agricultural production needs

    Ein implantierbares Telemetriesystem zur Impedanzspektroskopie

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    Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugĂ€nglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Die kontinuierliche Überwachung des intrakorporalen Zustandes von Geweben beispielsweise zur Erkennung ischĂ€mischer VorgĂ€nge nach gefĂ€ĂŸchirurgischen Eingriffen oder im Rahmen der Rejektionsdiagnostik lĂ€ĂŸt sich durch bisher vorhandene Meßsysteme nur bedingt erreichen. Speziell die direkte Erfassung sensitiver Gewebeparameter ĂŒber einen lĂ€ngeren Zeitraum ohne Belastung fĂŒr den Patienten stellt in diesem Zusammenhang ein Problem dar. In der nachfolgenden Arbeit wird das Konzept eines implantierbaren Telemetriesystems vorgestellt, das die Bewertung des Gewebezustandes ĂŒber die Messung der frequenzabhĂ€ngigen Bioimpedanz ermöglicht. Besondere Beachtung wird der Auslegung und Umsetzung der einzelnen Systemkomponenten sowie der Vorstellung erster in vitro Messungen zur Evaluierung des Meßsystems geschenkt

    Modelling historical and current irrigation water demand on the continental scale

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    Abstract. Water abstractions for irrigation purposes are higher than for any other pan-European water use sector and have a large influence on river runoff regimes. This modelling experiment assesses historic and current irrigation water demands for different crops in five arc minute spatial resolution for pan-Europe. Two different modelling frameworks have been applied in this study. First, soft-coupling the dynamic vegetation model LPJmL with the land use model LandSHIFT leads to overestimations of national irrigation water demands, which are rather high in the southern Mediterranean countries. This can be explained by unlimited water supply in the model structure and illegal or not gauged water abstractions in the reported data sets. The second modelling framework is WaterGAP3, which has an integrated conceptual crop specific irrigation module. Irrigation water requirements as modelled with WaterGAP3 feature a more realistic representation of pan-European water withdrawals. However, in colder humid regions, irrigation water demands are often underestimated. Additionally, a national database on crop-specific irrigated area and water withdrawal for all 42 countries within pan-Europe has been set up and integrated in both model frameworks

    Fermion sea along the sphaleron barrier

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    In this revised version we have improved the treatment of the top and bottom quark mass. This leads to slight changes of the numerical results, especially of those presented in Fig.4. The discussion of the numerical procedure and accuracy has been extended.Comment: 39 pages (LaTex) plus 5 figures (uuencoded postscript files); RUB-TPII-62/93, to appear in Phys.Rev.

    Estimulaçao cardĂ­aca atrioventricular sincrĂŽnica atravĂ©s de um eletrodo flutuante Ășnico (Modo VDD)

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    Um marcapasso bicameral que utiliza um eletrodo flutuante Ășnico para estimulaçao no modo VDD foi implantado em 25 pacientes com distĂșrbio da conduçao intra-cardĂ­aca do tipo bloqueio atrioventricular total (21 pacientes) ou de 2Âș grau (4 pacientes). Presumiu-se funçao sinusal normal atravĂ©s do eletrocardiograma convencional e da histĂłria clĂ­nica. As etiologias dos distĂșrbios de conduçao foram a miocardioesclerose (22 pacientes), cirĂșrgica (2 pacientes) ou a doença de Chagas (1 paciente). O eletrodo flutuante Ășnico SL 60 (Biotronik), dotado de dois sensores atriais situados a 13 cm da extremidade que contĂ©m o eletrodo ventricular unipolar, foi introduzido por via transvenosa. As medidas eletrofisiolĂłgicas (mĂ©dia ± erro padrao) no implante foram onda P de 2,87 ± 0,27 mV, QRS de 10,97 ± 0,92 mV e limiar de estimulaçao ventricular de 0,51 ± 0,04 V. O gerador de pulsos Dromos SL (Biotronik) foi mantido na programaçao padrao. ApĂłs implante os pacientes realizaram teste ergomĂ©trico e/ou eletrocardiograma ambulatorial de 24 horas. As complicaçoes registradas foram a perda da sensibilidade atrial em dois pacientes (8%), requerendo reposicionamento do eletrodo, insuficiĂȘncia cronotrĂłpica ao exercĂ­cio por bradicardia sinusal em um (4%) e estimulaçao de mĂșsculo peitoral ou inibiçao temporĂĄria do gerador por miopotenciais em um (4%), solucionada por reprogramaçao. Em atĂ© 6 meses de seguimento, 24 pacientes (96%) apresentam sincronismo atrioventricular adequado graças Ă  estimulaçao produzida pelo marcapasso implantado. O implante de um marcapasso atrioventricular sequencial com eletrodo flutuante Ășnico Ă© simples e a estimulaçao VDD Ă© efetiva em pacientes com bloqueio cardĂ­aco e funçao sinusal normal. Seu uso em pacientes chagĂĄsicos deve ser avaliado, pois miopotenciais cardĂ­acos reduzidos podem comprometer a sensibilidade atrial
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