910 research outputs found
Improved livelihoods in lower Limpopo: process documentation
Water resource management / Project planning / Project management / Participatory management / Community involvement / Irrigation schemes / Pumps / Dams / Canals / Mozambique / Lower Limpopo River Basin / Ndonga
Gender and irrigation in India: The Women's Irrigation Group of Jambar, South Gujarat
Irrigation management / Women in development / Gender / Female labor / Agricultural credit / Decision making / Irrigation programs / Rain-fed farming / Institution building / Pumping
Translating biomonitoring data into risk management and policy implementation options for a European Network on Human Biomonitoring
<p>Abstract</p> <p>Background</p> <p>The "European Environment & Health Action Plan 2004–2010" originates from the concern of the European Commission on the well-being of individuals and the general population. Through this plan, the Commission has set the objectives to improve the information chain for a better understanding of the link between sources of pollution and health effects, to better identify existing knowledge gaps, and improve policy making and communication strategies. Human biomonitoring (HBM) has been included as one of the tools to achieve these objectives. As HBM directly measures the amount of a chemical substance in a person's body, taking into account often poorly understood processes such as bioaccumulation, excretion, metabolism and the integrative uptake variability through different exposure pathways, HBM data are much more relevant for risk assessment than extrapolations from chemical concentrations in soil, air, and water alone. However, HBM primarily is a stepping stone between environmental and health data, and the final aim should be an integrated and holistic systematic risk assessment paradigm where HBM serves as a pivotal point between environment and health, on the one hand leaning on environmental data to provide detailed information on the sources and pathways of pollutants that enter the human body, and on the other hand clarifying new and existing hypotheses on the relationship between environmental pollutants and the prevalence of diseases. With the large amount of data that is being gathered in the different national survey projects, and which is expected to become available in Europe in the near future through the expected European Pilot Project on HBM, a framework to optimize data interpretation from such survey projects may greatly enhance the usefulness of HBM data for risk managers and policy makers.</p> <p>Results</p> <p>This paper outlines an hierarchic approach, based on the stepwise formulation of 4 subsequent steps, that will eventually lead to the formulation of a variety of policy relevant risk reduction options.</p> <p>Conclusion</p> <p>Although the usefulness of this approach still needs to be tested, and potential fine-tuning of the procedure may be necessary, approaching the policy implications of HBM in an objective framework will prove to be essential.</p
Ram Pressure Stripping Made Easy: An Analytical Approach
The removal of gas by ram pressure stripping of galaxies is treated by a
purely kinematic description. The solution has two asymptotic limits: if the
duration of the ram pressure pulse exceeds the period of vertical oscillations
perpendicular to the galactic plane, the commonly used quasi-static criterion
of Gunn & Gott is obtained which uses the maximum ram pressure that the galaxy
has experienced along its orbit. For shorter pulses the outcome depends on the
time-integrated ram pressure. This parameter pair fully describes the gas mass
fraction that is stripped from a given galaxy. This approach closely reproduces
results from SPH simulations. We show that typical galaxies follow a very tight
relation in this parameter space corresponding to a pressure pulse length of
about 300 Myr. Thus, the Gunn & Gott criterion provides a good description for
galaxies in larger clusters. Applying the analytic description to a sample of
232 Virgo galaxies from the GoldMine database, we show that the ICM provides
indeed the ram pressures needed to explain the deficiencies. We also can
distinguish current and past strippers, including objects whose stripping state
was unknown.Comment: Accepted for publication in MNRAS. Several interactive JavaScript
tools which evaluate the analytical considerations of this paper are
available at http://www.astrophysik.uni-kiel.de/~koeppen/JS/RPShome.htm
Knowledge uncertainties in environmental conflicts:How the mussel fishery controversy in the Dutch Wadden Sea became depoliticised
<p>Policy-makers and scientists often expect that controversies in public policy can be solved by gathering more knowledge, even though this linear model of expertise is widely criticised in social studies of science. To shed more light on this expectation, the role of scientific uncertainties in controversies on mussel fishery in the Dutch Wadden Sea (1990–2016) is investigated. The analysis shows that mussel fishery regulation decisions were primarily based on government authority, not on scientific knowledge. Expectations of policy-makers and scientists on conflict resolution by more research were not met, because the knowledge debate was politicised over ambiguous knowledge claims. The controversy was depoliticised by a political covenant between the conflicting parties. The case study confirms that science-based knowledge fails to guide policy-making as expected in the linear model, and demonstrates how science plays important strategic, procedural and instrumental roles in structuring interactions between stakeholders in nature protection conflicts.</p
Initial Ionization of Compressible Turbulence
We study the effects of the initial conditions of turbulent molecular clouds
on the ionization structure in newly formed H_{ii} regions, using
three-dimensional, photon-conserving radiative transfer in a pre-computed
density field from three-dimensional compressible turbulence. Our results show
that the initial density structure of the gas cloud can play an important role
in the resulting structure of the H_{ii} region. The propagation of the
ionization fronts, the shape of the resulting H_{ii} region, and the total mass
ionized depend on the properties of the turbulent density field. Cuts through
the ionized regions generally show ``butterfly'' shapes rather than spherical
ones, while emission measure maps are more spherical if the turbulence is
driven on scales small compared to the size of the H_{ii} region. The
ionization structure can be described by an effective clumping factor , where is number density of the gas. The larger
the value of , the less mass is ionized, and the more irregular the
H_{ii} region shapes. Because we do not follow dynamics, our results apply only
to the early stage of ionization when the speed of the ionization fronts
remains much larger than the sound speed of the ionized gas, or Alfv\'en speed
in magnetized clouds if it is larger, so that the dynamical effects can be
negligible.Comment: 9 pages, 10 figures, version with high quality color images can be
found in http://research.amnh.org/~yuexing/astro-ph/0407249.pd
Design of Test Articles and Monitoring System for the Characterization of HIRF Effects on a Fault-Tolerant Computer Communication System
This report describes the design of the test articles and monitoring systems developed to characterize the response of a fault-tolerant computer communication system when stressed beyond the theoretical limits for guaranteed correct performance. A high-intensity radiated electromagnetic field (HIRF) environment was selected as the means of injecting faults, as such environments are known to have the potential to cause arbitrary and coincident common-mode fault manifestations that can overwhelm redundancy management mechanisms. The monitors generate stimuli for the systems-under-test (SUTs) and collect data in real-time on the internal state and the response at the external interfaces. A real-time health assessment capability was developed to support the automation of the test. A detailed description of the nature and structure of the collected data is included. The goal of the report is to provide insight into the design and operation of these systems, and to serve as a reference document for use in post-test analyses
Plan for the Characterization of HIRF Effects on a Fault-Tolerant Computer Communication System
This report presents the plan for the characterization of the effects of high intensity radiated fields on a prototype implementation of a fault-tolerant data communication system. Various configurations of the communication system will be tested. The prototype system is implemented using off-the-shelf devices. The system will be tested in a closed-loop configuration with extensive real-time monitoring. This test is intended to generate data suitable for the design of avionics health management systems, as well as redundancy management mechanisms and policies for robust distributed processing architectures
Chemical Abundance Gradients in the Star-Forming Ring Galaxies
Ring waves of star formation, propagating outwardly in the galactic disks,
leave chemical abundance gradients in their wakes. We show that the relative
[Fe/O] abundance gradients in ring galaxies can be used as a tool for
determining the role of the SNIa explosions in their chemical enrichment. We
consider two mechanisms which can create outwardly propagating star forming
rings in a purely gaseous disk -- a self-induced wave and a density wave, and
demonstrate that the radial distribution of the relative [Fe/O] abundance
gradients does not depend on the particular mechanism of the wave formation or
on the parameters of the star-forming process. We show that the [Fe/O] profile
is determined by the velocity of the wave, initial mass function, and the
initial chemical composition of the star-forming gas. If the role of SNIa
explosions is negligible in the chemical enrichment, the ratio [Fe/O] remains
constant throughout the galactic disk with a steep gradient at the wave front.
If SNIa stars are important in the production of cosmic iron, the [Fe/O] ratio
has gradient in the wake of the star-forming wave with the value depending on
the frequency of SNIa explosions.Comment: Uses aas2pp4.sty and epsfig.sty, 7 pages including one figure To
appear in Astrophysical Journa
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