147 research outputs found
Modelling the effects of land-use and land-cover change on water availability in the Jordan River region
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&times;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
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Dual Beam FIB for Imaging, Nano-Sectioning and Sample Preparation of Spores: Initial Results.
Results from the first use of Focused Ion Beam (FIB) technology to section Bacillus spores at LLNL in a dual-beam (electron and ion) instrument is presented and discussed. With the use of a dual-beam instrument, high resolution imaging of single spores using low voltage scanning electron microscopy followed by FIB sectioning, SEM imaging of internal structure of the same spore is demonstrated to be possible. Additionally, FIB is shown to be able to precisely micro-machine spores thus potentially facilitating micro-scale experiments on single spores
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Chemically Specific Cellular Imaging of Biofilm Formation
This document and the accompanying manuscripts summarize the technical accomplishments for our one-year LDRD-ER effort. Biofilm forming microbes have existed on this planet for billions of years and make up 60% of the biological mass on earth. Such microbes exhibit unique biochemical pathways during biofilm formation and play important roles in human health and the environment. Microbial biofilms have been directly implicated in, for example, product contamination, energy losses, and medical infection that cost the loss of human lives and billions of dollars. In no small part due to the lack of detailed understanding, biofilms unfortunately are resistant to control, inhibition, and destruction, either through treatment with antimicrobials or immunological defense mechanisms of the body. Current biofilm research has concentrated on the study of biofilms in the bulk. This is primarily due to the lack of analytical and physical tools to study biofilms non-destructively, in three dimensions, and on the micron or sub-micron scale. This has hindered the development of a clear understanding of either the early stage mechanisms of biofilm growth or the interactions of biofilms with their environment. Enzymatic studies have deduced a biochemical reaction that results in the oxidation of reduced sulfur species with the concomitant reduction of nitrate, a common groundwater pollutant, to dinitrogen gas by the bacterium, Thiobacillus denitrificans (TD). Because of its unique involvement in biologically relevant environmental pathways, TD is scheduled for genome sequencing in the near future by the DOE's Joint Genome Institute and is of interest to DOE's Genomes to Life Program. As our ecosystem is exposed to more and more nitrate contamination large scale livestock and agricultural practices, a further understanding of biofilm formation by organisms that could alleviate these problems is necessary in order to protect out biosphere. However, in order to study this complicated organism, we needed to first turn our attention to a well understood organism. Pseudomonas aeruginosa (PA) is a well-studied organism and will be used to compare our results with others. Then, we will turn our attention to TD. It is expected that the research performed will provide key data to validate biochemical studies of TD and result in high profile publications in leading journals. For this project, our ultimate goal was to combine both Magnetic Resonance Imaging (MRI) and Nuclear Magnetic Resonance (NMR) experimental analysis with computer simulations to provide unique 3D molecular structural, dynamics, and functional information on the order of microns for this DOE mission relevant microorganism, T. denitrificans. For FY05, our goals were to: (1) Determine proper media for optimal growth of PA; growth rate measurements in that media and characterization of metabolite signatures during growth via {sup 1}H and {sup 13}C NMR, (2) Determine and build mineral, metal, and implant material surfaces to support growth of PA, (3) Implementing new MRI sequences to image biofilms more efficiently and increase resolution with new hardware design, (4) Develop further diffusion and flow MRI measurements of biofilms and biofilm formation with different MRI pulse sequences and different hardware design, and (5) Develop a zero dimension model of the rate of growth and the metabolite profiles of PA. Our major accomplishments are discussed in the following text. However, the bulk of this work is described in the attached manuscript entitled, ''NMR Metabolomics of Planktonic and Biofilm Modes of Growth in Pseudomonas aeruginosa''. This paper will be submitted to the Journal of Bacteriology in coming weeks. In addition, this one-year effort has lead to our incorporation into the Enhanced Surveillance Campaign during FY05 for some proof-of-principle MRI measurements on polymers. We are currently using similar methods to evaluate these polymers. In addition, this work on MRI measurements on polymers has lead to a paper entitled, ''Characterization of local deformation in filled-silicone elastomers subject to high strain NMR MOUSE and Magnetic Resonance Imaging as a diagnostic tool for detection of inhomogeneities''
Exploring future agricultural development and biodiversity in Uganda, Rwanda and Burundi: a spatially explicit scenario-based assessment
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
Spontaneous annihilation of high-density matter in the electroweak theory
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
Ein implantierbares Telemetriesystem zur Impedanzspektroskopie
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 Ăberwachung des intrakorporalen Zustandes von Geweben beispielsweise zur Erkennung ischĂ€mischer VorgĂ€nge nach gefĂ€Ăchirurgischen Eingriffen oder im Rahmen der Rejektionsdiagnostik lĂ€Ăt sich durch bisher vorhandene MeĂsysteme 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 MeĂsystems geschenkt
Prompt Multi-Gluon Production in High Energy Collisions from Singular Yang-Mills Solutions
We study non-perturbative parton-parton scattering in the Landau method using
singular O(3) symmetric solutions to the Euclidean Yang-Mills equations. These
solutions combine instanton dynamics (tunneling) and overlap (transition)
between incoming and vacuum fields. We derive a high-energy solution at small
Euclidean times, and assess its susequent escape and decay into gluons in
Minkowski space-time. We describe the spectrum of the {\it outgoing} gluons and
show that it is related through a particular rescaling to the Yang-Mills
sphaleron explosion studied earlier. We assess the number of {\it incoming}
gluons in the same configuration, and argue that the observed scaling is in
fact more general and describes the energy dependence of the spectra and
multiplicities at {\it all} energies. Applications to hadron-hadron and
nucleus-nucleus collisions are discussed elsewhere
Fermion sea along the sphaleron barrier
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.
Estudo multicĂȘntrico comparativo de quatro diferentes tipos de sensores: atividade, acelerĂŽmetro, temperatura e perĂodo de prĂ©-ejeçao
Recentemente diferentes princĂpios tĂȘm sido utilizados para estimular o coraçao na tentativa de recuperar o dĂ©bito cardĂaco. Neste estudo multicĂȘntrico, foram comparadas as respostas Ă estimulaçao por 4 tipos de sensores, sendo 3 tipos de resposta de alça aberta (atividade fĂsica, acelerĂŽmetro e temperatura venosa central) implantados em 30 (SSIR-8 e DDDR-22), 9 (SSIR-5 -e DDDR-4) e 12 (SSIR) pacientes respectivamente. Um outro sensor do tipo alça fechada, sensĂvel Ă s variaçoes do sistema nervoso autĂŽnomo, foi implantado em 57 pacientes, todos no modo DDDR. Os resultados obtidos durante a realizaçao de atividade fĂsica diĂĄria, de teste ergomĂ©trico e de Holter de 24 horas foram comparados, sendo possĂvel observar uma maior fidelidade na curva de resposta de freqĂŒĂȘncia frente a atividade fĂsica, nos pacientes submetidos Ă estimulaçao de alça fechada
Estudo multicĂȘntrico comparativo de quatro diferentes tipos de sensores: atividade, acelerĂŽmetro, temperatura e perĂodo de prĂ©-ejeçao
Recentemente diferentes princĂpios tĂȘm sido utilizados para estimular o coraçao na tentativa de recuperar o dĂ©bito cardĂaco. Neste estudo multicĂȘntrico, foram comparadas as respostas Ă estimulaçao por 4 tipos de sensores, sendo 3 tipos de resposta de alça aberta (atividade fĂsica, acelerĂŽmetro e temperatura venosa central) implantados em 30 (SSIR-8 e DDDR-22), 9 (SSIR-5 -e DDDR-4) e 12 (SSIR) pacientes respectivamente. Um outro sensor do tipo alça fechada, sensĂvel Ă s variaçoes do sistema nervoso autĂŽnomo, foi implantado em 57 pacientes, todos no modo DDDR. Os resultados obtidos durante a realizaçao de atividade fĂsica diĂĄria, de teste ergomĂ©trico e de Holter de 24 horas foram comparados, sendo possĂvel observar uma maior fidelidade na curva de resposta de freqĂŒĂȘncia frente a atividade fĂsica, nos pacientes submetidos Ă estimulaçao de alça fechada
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