1,202 research outputs found
Ensuring health and food safety from rapidly expanding wastewater irrigation in South Asia: BMZ final report 2005-2008
Wastewater irrigation / Institutions / Public health / Health hazards / Diseases / Cropping systems / Vegetables / Fodder / Livestock / Risk assessment / Economic evaluation / Surveys / GIS / Research priorities / South Asia / India / Pakistan / Hyderabad / Faisalabad / Musi River
Impacts of agricultural innovation and transformation of the mountainous hinterland in the Mediterranean: An example from Southern Spain (Costa Granadina)
Between 1985 and 1989 and in 1994 an agroecologicaI research was carried out at the Mediterranean coast of Andalucía (Southern Spain). Comparison of aerial photos of 1950 and 1978, interviews with farmers and field work made clear that the landscape is subject to enormous changes. The innovation of agricultural practices cause manifold ecological consequences. Main results are: The traditional land use pattern was replaced by market oriented agricultural practices. The changes of the land use pattern occurred very quickly starting in the early eighty's, not reaching their peak up to now. Main feature of the development is the destruction of the landscape by ecologically non - adapted methods of terracing steep slopes, which were formerly protected by traditional terraces. Heterogeneous development of the higher Alpujarra and the coastal plains with respect to the emigration and immigration pattern is threatening the interaction between both areas, especially the water management. The coastal plains are entirely dependent on the water resources of the Sierra Nevada and upper Alpujarra. Dryland farming has been abandoned nearly completely.Una investigación agroecológica se llevó a cabo entre 1985 y 1989, y en 1994, en la costa mediterránea de Andalucía (Sur de España). La comparación de fotografías aéreas de 1950 y 1978, las entrevistas a agricultores y el trabajo de campo revelan que el paisaje ha sufrido grandes cambios. Las innovaciones en las prácticas agrícolas han tenido múltiples consecuencias ecológicas. Los principales resultados son: El uso tradicional de la tierra ha sido sustituido por prácticas agrícolas orientadas al mercado. Los cambios en las pautas de uso del suelo han sido muy rápidos, iniciándose a comienzos de la década de los ochenta y no alcanzando el máximo hasta hoy. El rasgo principal del desarrollo ha sido la destrucción del paisaje mediante métodos ecológicamente inapropiados de construcción de terrazas en fuertes pendientes, que antes quedaban protegidas por el aterrazamiento tradicional. El desarrollo diferente de la Alta Alpujarra y de las llanuras costeras en relación con las pautas de inmigración y emigración está amenazando la interacción entre ambas áreas, especialmente en lo que respecta a la gestión del agua. Las llanuras costeras dependen por completo de los recursos hídricos de la Sierra Nevada y de la Alta Alpujarra. El cultivo de secano ha sido abandonado casi por completo
New Measurements and Quantitative Analysis of Electron Backscattering in the Energy Range of Neutron Beta-Decay
We report on the first detailed measurements of electron backscattering from
plastic scintillator targets, extending our previous work on beryllium and
silicon targets. The scintillator experiment posed several additional
experimental challenges associated with charging of the scintillator target,
and those challenges are addressed in detail. In addition, we quantitatively
compare the energy and angular distributions of this data, and our previous
data, with electron transport simulations based on the Geant4 and Penelope
Monte Carlo simulation codes. The Penelope simulation is found globally to give
a superior description of the data. Such information is crucial for a broad
array of weak-interaction physics experiments, where electron backscattering
can give rise to the dominant detector-related systematic uncertainty.Comment: 7 pages, 3 figure
Enhanced Perturbative Continuous Unitary Transformations
Unitary transformations are an essential tool for the theoretical
understanding of many systems by mapping them to simpler effective models. A
systematically controlled variant to perform such a mapping is a perturbative
continuous unitary transformation (pCUT) among others. So far, this approach
required an equidistant unperturbed spectrum. Here, we pursue two goals: First,
we extend its applicability to non-equidistant spectra with the particular
focus on an efficient derivation of the differential flow equations, which
define the enhanced perturbative continuous unitary transformation (epCUT).
Second, we show that the numerical integration of the flow equations yields a
robust scheme to extract data from the epCUT. The method is illustrated by the
perturbation of the harmonic oscillator with a quartic term and of the two-leg
spin ladders in the strong-rung-coupling limit for uniform and alternating rung
couplings. The latter case provides an example of perturbation around a
non-equidistant spectrum.Comment: 27 pages, 18 figures; separated methodological background from
introduction, added perturbed harmonic oscillator for additional
illustration, added explicit solution of deepCUT equation
Impact of Uncertainties in Hadron Production on Air-Shower Predictions
At high energy, cosmic rays can only be studied by measuring the extensive
air showers they produce in the atmosphere of the Earth. Although the main
features of air showers can be understood within a simple model of successive
interactions, detailed simulations and a realistic description of particle
production are needed to calculate observables relevant to air shower
experiments. Currently hadronic interaction models are the main source of
uncertainty of such simulations. We will study the effect of using different
hadronic models available in CORSIKA and CONEX on extensive air shower
predictions.Comment: 12 pages, 6 figures, to appear in the proceedings of International
Conference on Interconnection between High Energy Physics and Astroparticle
Physics: From Colliders to Cosmic Rays, Prague, Czech Republic, 7-13 Sep 200
Comparison of the pattern of metastatic spread of squamous cell cancer and adenocarcinoma of the uterine cervix
Retrospective review of medical records and autopsy findings in patients dying of squamous cell cancer or adenocarcinoma of the uterine cervix was undertaken to evaluate for possible differences in biologic behavior between these tumor types. Twenty-one patients with each tumor type were evaluated. Patients with adenocarcinoma were found to have a higher incidence of tumor involvement of the paraaortic lymph nodes (13/21 vs 6/20, P P P P P < 0.05) was also significantly more frequent in patients with adenocarcinoma. These findings suggest that this tumor may behave differently in regard to pattern of metastatic spread or response to therapy. The therapeutic implications of these findings deserve further study.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27919/1/0000342.pd
A stochastic flow rule for granular materials
There have been many attempts to derive continuum models for dense granular
flow, but a general theory is still lacking. Here, we start with Mohr-Coulomb
plasticity for quasi-2D granular materials to calculate (average) stresses and
slip planes, but we propose a "stochastic flow rule" (SFR) to replace the
principle of coaxiality in classical plasticity. The SFR takes into account two
crucial features of granular materials - discreteness and randomness - via
diffusing "spots" of local fluidization, which act as carriers of plasticity.
We postulate that spots perform random walks biased along slip-lines with a
drift direction determined by the stress imbalance upon a local switch from
static to dynamic friction. In the continuum limit (based on a Fokker-Planck
equation for the spot concentration), this simple model is able to predict a
variety of granular flow profiles in flat-bottom silos, annular Couette cells,
flowing heaps, and plate-dragging experiments -- with essentially no fitting
parameters -- although it is only expected to function where material is at
incipient failure and slip-lines are inadmissible. For special cases of
admissible slip-lines, such as plate dragging under a heavy load or flow down
an inclined plane, we postulate a transition to rate-dependent Bagnold
rheology, where flow occurs by sliding shear planes. With different yield
criteria, the SFR provides a general framework for multiscale modeling of
plasticity in amorphous materials, cycling between continuum limit-state stress
calculations, meso-scale spot random walks, and microscopic particle
relaxation
Smoothed Particle Hydrodynamics for Relativistic Heavy Ion Collisions
The method of smoothed particle hydrodynamics (SPH) is developped
appropriately for the study of relativistic heavy ion collision processes. In
order to describe the flow of a high energy but low baryon number density
fluid, the entropy is taken as the SPH base. We formulate the method in terms
of the variational principle. Several examples show that the method is very
promising for the study of hadronic flow in RHIC physics.Comment: 14 pages, 8figure
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