289 research outputs found
Participatory diagnosis and adaptive management of small-scale fisheries in the Niger River Basin
In a broad sense, analysis of âresilienceâ is about the capacity of systems to adapt to
shocks, recognizing that disturbance and change are integral component of complex
systems. More formally, resilience analysis proposes to focus on mechanisms and
processes that help systems absorbing perturbations and shocks, and coping with
uncertainty and risks. Defined in such a way, the concept of resilience thus appears
particularly useful for the management of small-scale fisheries. However, while the
resilience concept is appealing, particularly in the face of the failure of current
management approaches, the danger is that it remains largely academic and theoretical,
and not of a great help in effectively improving the way natural resources are managed
on the ground. The challenge, therefore, lies in a pragmatic approach to operationalizing
the concept of resilience and making its implementation on the ground practical and
meaningful. In this project we propose a framework aimed at this objective and we test
it in the specific context of small-scale fisheries in the Niger River Basin
Improved fisheries productivity and management in tropical reservoirs
âImproved fisheries productivity and management in tropical reservoirsâ
The objective of the project was to contribute to the current research on reservoirs enhancement
fisheries in tropical countries through the implementation of a series of action-research activities
implemented in two small reservoirs in the Indo-Gangetic basin in India, and two very large
reservoirs in Africa, the Lake Nasser (Egypt), and the Volta Lake (Ghana). Socio-institutional
analyses were also conducted in these reservoirs to improve our knowledge regarding some of the
main social processes that influence reservoir productivity. Overall the results of the project stress
that while the natural biophysical constraints of the reservoirs are important in defining the
ecological production processes, it is the socio-economic settings characterizing the
community/societies around the reservoirs that eventually shape the human production
enhancement possibilities
Inner structure of the Puy de DËome volcano: cross-comparison of geophysical models (ERT, gravimetry, muon imaging)
International audienceMuon imaging of volcanoes and of geological structures in general is actively being developed by several groups in the world. It has the potential to provide 3-D density distributions with an accuracy of a few percent. At this stage of development, comparisons with established geophysical methods are useful to validate the method. An experiment has been carried out in 2011 and 2012 on a large trachytic dome, the Puy de DËome volcano, to perform such a comparison of muon imaging with gravimetric tomography and 2-D electrical resistivity tomography. Here, we present the preliminary results for the last two methods. North-south and east-west resistivity profiles allow us to model the resistivity distribution down to the base of the dome. The modelling of the Bouguer anomaly provides models for the density distribution within the dome that are directly comparable with the results from the muon imaging. Our ultimate goal is to derive a model of the dome using the joint interpretation of all sets of data
Air shower simulation for background estimation in muon tomography of volcanoes
International audienceOne of the main sources of background for the radiography of volcanoes using atmospheric muons comes from the accidental coincidences produced in the muon telescopes by charged particles belonging to the air shower generated by the primary cosmic ray. In order to quantify this background effect, Monte Carlo simulations of the showers and of the detector are developed by the TOMUVOL collaboration. As a first step, the atmospheric showers were simulated and investigated using two Monte Carlo packages, CORSIKA and GEANT4.We compared the results provided by the two programs for the muonic component of vertical proton-induced showers at three energies: 1, 10 and 100 TeV. We found that the spatial distribution and energy spectrum of the muons were in good agreement for the two codes
Adaptation to flooding in lowâincome urban settlements in the least developed countries: A systems approach
This study aims to use a whole systems approach (1) to understand the processes of adaptation to flooding of the urban poor; (2) to identify new knowledge of how lowâincome settlements might better adapt to climatic risks; and (3) to begin to develop appropriate guidance on this. Lowâincome urban settlements in the least developed countries (LDCs) present an extreme case where catastrophic natural hazards and chronic social hazards overlap. These lowâincome urban populations face the greatest adaptation challenges as they often occupy informal settlements that are particularly exposed to hazards, and have multiple vulnerabilities arising from their lack of basic services. There is a dynamic complexity of issues arising from the many levels of actor involved and multiple social and physical factors. Analysing such a complex phenomenon calls for a specific conceptual framing, and a systems theory approach is suggested to provide a holistic perspective. The case study for this research is located in Dhaka East, where there is both high vulnerability to flooding, and a significant lowâincome population. The research has adopted a mixed methods approach involving different data collection methods governed by the different scales and actors being investigated. The research develops new systems understandings of perceptions and experiences of the local population about adaptation processes in lowâincome urban settlements, and how these processes may be positively influenced by integrating bottomâup and topâdown approaches
Vulnerable people, vulnerable resources? Exploring the relationship between people's vulnerability and the sustainability of community-managed natural resources
Participatory approaches to the management of common-pool resources (CPRs) are built on the premise that resource-users are dependent on the productivity of the resource and therefore have the incentive to act as resource stewards if empowered to do so. Yet many CPR users have only temporary interest in using the resources. Moreover, they are vulnerable to a range of stressors and risks unrelated to resource access and sustainability concerns. Both of these may undermine such incentives. Furthermore, discounting theory posits that high vulnerability shortens time horizons so that vulnerable CPR users might be expected to heavily discount future benefits from resource conservation. We present an ethnographic study carried out in two communities on Lake Victoria, Uganda, where fisher folk face a range of elevated risks to health and security. These immediate risks undermine participatory fishery management but this does not necessarily indicate inherently short time-horizons; for many, fishing and fish-trading are not perceived as a life-long occupation but as a means to generate capital for investment in other businesses. Thus, whether they are vulnerable or not, it cannot simply be assumed that current CPR users will have a long-term interest in participating in resource management. Incentivizing participation in CPR management for long-term sustainability may have to address both peopleâs wider vulnerabilities and aspirations
Experimental demonstration of quantum correlations over more than 10 km
Energy and time entangled photons at a wavelength of 1310 nm are produced by
parametric downconversion in a KNbO3 crystal and are sent into all-fiber
interferometers using a telecom fiber network. The two interferometers of this
Franson-type test of the Bell-inequality are located 10.9 km apart from one
another. Two-photon fringe visibilities of up to 81.6 % are obtained. These
strong nonlocal correlations support the nonlocal predictions of quantum
mechanics and provide evidence that entanglement between photons can be
maintained over long distances.Comment: 5 pages, REVTeX, 3 postscript figures include
Study of Inclusive Strange-Baryon Production and Search for Pentaquarks in Two-Photon Collisions at LEP
Measurements of inclusive production of the Lambda, Xi- and Xi*(1530) baryons
in two-photon collisions with the L3 detector at LEP are presented. The
inclusive differential cross sections for Lambda and Xi- are measured as a
function of the baryon transverse momentum, pt, and pseudo-rapidity, eta. The
mean number of Lambda, Xi- and Xi*(1530) baryons per hadronic two-photon event
is determined in the kinematic range 0.4 GeV < pt< 2.5 GeV, |eta| < 1.2.
Overall agreement with the theoretical models and Monte Carlo predictions is
observed. A search for inclusive production of the pentaquark theta+(1540) in
two-photon collisions through the decay theta+ -> proton K0s is also presented.
No evidence for production of this state is found
Lambda and Sigma0 Pair Production in Two-Photon Collisions at LEP
Strange baryon pair production in two-photon collisions is studied with the
L3 detector at LEP. The analysis is based on data collected at e+e-
centre-of-mass energies from 91 GeV to 208 GeV, corresponding to an integrated
luminosity of 844 pb-1. The processes gamma gamma -> Lambda Anti-lambda and
gamma gamma -> Sigma0 Anti-sigma0 are identified. Their cross sections as a
function of the gamma gamma centre-of-mass energy are measured and results are
compared to predictions of the quark-diquark model
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