1,700 research outputs found
Rural poverty in Ecuador : a qualitative assessment
A complement to recent in-depth quantitative analyses of rural poverty in Ecuador, this is a report on the results of the Rural Qualitative Assessment in living conditions in rural communities in all three Ecuador's diverse regions. Using a variety of qualitative techniques, the research aimed to assess what poverty means to marginalized rural families, what kind of survival strategies families use in times of hardship, and what these families believe is needed to alleviate poverty. Several key messages emerge: 1) rural communities with the same characteristics (such as area, soil quality, and ethnic background) are actually very heterogeneous in their command of land resources, definition of well-being, range of economic activities, and recommendations for what is needed to overcome poverty; 2) in times of hardship, families have complemented income for traditional sources with earnings from new activities. In addition to migration, which plays a pivotal role in all communities, piecework and weaving are important to income generation in the Sierra, small businesses are important in the Costa, and increased production of cash crops is important in the Oriente. Families have also reduced expenditures on clothing, fiestas, and food. Spending less on food is alarming as malnutrition rates in rural Ecuador are already very high; and 3) poor rural families express very practical solutions to overcoming poverty. They don't demand sweeping changes. Overwhelmingly, they suggest measures that will make available land and human resources more productive. Almost half the suggestions from poor rural families have to do with infrastructure. Many families also want training courses (both agricultural and nonagricultural).Public Health Promotion,Environmental Economics&Policies,Agricultural Knowledge&Information Systems,Health Monitoring&Evaluation,Water Conservation,Environmental Economics&Policies,Agricultural Knowledge&Information Systems,Crops&Crop Management Systems,Health Monitoring&Evaluation,Housing&Human Habitats
Diffusion Limited Aggregation with Power-Law Pinning
Using stochastic conformal mapping techniques we study the patterns emerging
from Laplacian growth with a power-law decaying threshold for growth
(where is the radius of the particle cluster). For
the growth pattern is in the same universality class as diffusion
limited aggregation (DLA) growth, while for the resulting patterns
have a lower fractal dimension than a DLA cluster due to the
enhancement of growth at the hot tips of the developing pattern. Our results
indicate that a pinning transition occurs at , significantly
smaller than might be expected from the lower bound
of multifractal spectrum of DLA. This limiting case shows that the most
singular tips in the pruned cluster now correspond to those expected for a
purely one-dimensional line. Using multifractal analysis, analytic expressions
are established for both close to the breakdown of DLA universality
class, i.e., , and close to the pinning transition, i.e.,
.Comment: 5 pages, e figures, submitted to Phys. Rev.
Anisotropic Diffusion Limited Aggregation
Using stochastic conformal mappings we study the effects of anisotropic
perturbations on diffusion limited aggregation (DLA) in two dimensions. The
harmonic measure of the growth probability for DLA can be conformally mapped
onto a constant measure on a unit circle. Here we map preferred directions
for growth of angular width to a distribution on the unit circle which
is a periodic function with peaks in such that the width
of each peak scales as , where defines the
``strength'' of anisotropy along any of the chosen directions. The two
parameters map out a parameter space of perturbations that allows a
continuous transition from DLA (for or ) to needle-like fingers
as . We show that at fixed the effective fractal dimension of
the clusters obtained from mass-radius scaling decreases with
increasing from to a value bounded from below by
. Scaling arguments suggest a specific form for the dependence
of the fractal dimension on for large , form which compares
favorably with numerical results.Comment: 6 pages, 4 figures, submitted to Phys. Rev.
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Impacts of global change on water-related sectors and society in a trans-boundary central European river basin – Part 2: From eco-hydrology to water demand management
This second part of the paper presents the details of the eco-hydrological model SWIM simulating the natural water supply and its coupling to WBalMo, a water management model.
Based on the climate scenarios of the STAR model, SWIM simulates the natural water and matter fluxes for the entire Elbe River area. All relevant processes are modelled for hydrotopes and the resulting discharges are accumulated in subbasins. The output data are input for the water management model WBalMo and the quality models Moneris and QSim.
WBalMo takes storage management, inputs and withdrawals into account and analyses how demands by industry, power plants and households will be met at changing natural supply conditions. Some of the first results shall be presented here
Residual disorder and diffusion in thin Heusler alloy films
Co2FeSi/GaAs(110) and Co2FeSi/GaAs(111)B hybrid structures were grown by
molecular-beam epitaxy and characterized by transmission electron microscopy
(TEM) and X-ray diffraction. The films contained inhomogeneous distributions of
ordered L2_1 and B2 phases. The average stoichiometry was controlled by lattice
parameter measurements, however diffusion processes lead to inhomogeneities of
the atomic concentrations and the degradation of the interface, influencing
long-range order. An average long-range order of 30-60% was measured by
grazing-incidence X-ray diffraction, i.e. the as-grown Co2FeSi films were
highly but not fully ordered. Lateral inhomogeneities of the spatial
distribution of long-range order in Co2FeSi were found using dark-field TEM
images taken with superlattice reflections
New Algorithm for Parallel Laplacian Growth by Iterated Conformal Maps
We report a new algorithm to generate Laplacian Growth Patterns using
iterated conformal maps. The difficulty of growing a complete layer with local
width proportional to the gradient of the Laplacian field is overcome. The
resulting growth patterns are compared to those obtained by the best algorithms
of direct numerical solutions. The fractal dimension of the patterns is
discussed.Comment: Sumitted to Phys. Rev. Lett. Further details at
http://www.pik-potsdam.de/~ander
Deformation of feldspar at greenschist facies conditions – the record of mylonitic pegmatites from the Pfunderer Mountains, Eastern Alps
Deformation microstructures of albitic plagioclase and K-feldspar were investigated in
mylonitic pegmatites from the Austroalpine basement south of the western
Tauern Window by polarized light microscopy, electron microscopy and electron
backscatter diffraction to evaluate feldspar deformation mechanisms at
greenschist facies conditions. The main mylonitic characteristics are
alternating almost monophase quartz and albite layers, surrounding
porphyroclasts of deformed feldspar and tourmaline. The dominant deformation
microstructures of K-feldspar porphyroclasts are intragranular fractures at a
high angle to the stretching lineation. The fractures are healed or sealed by
polyphase aggregates of albite, K-feldspar, quartz and mica, which also occur
along intragranular fractures of tourmaline and strain shadows around other
porphyroclasts. These polyphase aggregates indicate dissolution–precipitation
creep. K-feldspar porphyroclasts are partly replaced by albite characterized
by a cuspate interface. This replacement is interpreted to take place by
interface-coupled dissolution–precipitation driven by a solubility difference
between K-feldspar and albite. Albite porphyroclasts are replaced at
boundaries parallel to the foliation by fine-grained monophase albite
aggregates of small strain-free new grains mixed with deformed fragments.
Dislocation glide is indicated by bent and twinned albite porphyroclasts with
internal misorientation. An indication of effective dislocation climb with
dynamic recovery, for example, by the presence of subgrains, is systematically
missing. We interpret the grain size reduction of albite to be the result of
coupled dislocation glide and fracturing (low-temperature plasticity).
Subsequent growth is by a combination of strain-induced grain boundary
migration and formation of growth rims, resulting in an aspect ratio of albite
with the long axis within the foliation. This strain-induced replacement by
nucleation (associated dislocation glide and microfracturing) and subsequent
growth is suggested to result in the observed monophase albite layers,
probably together with granular flow. The associated quartz layers show
characteristics of dislocation creep by the presence of subgrains, undulatory
extinction and sutured grain boundaries. We identified two endmember matrix
microstructures: (i) alternating layers of a few hundred micrometres' width,
with isometric, fine-grained feldspar (on average 15 µm in diameter)
and coarse-grained quartz (a few hundred micrometres in diameter),
representing lower strain compared to (ii) alternating thin layers of some
tens of micrometres' width composed of fine-grained quartz (<20 µm in diameter)
and coarse elongated albite grains (long axis of a few tens of
micrometres) defining the foliation, respectively. Our observations indicate
that grain size reduction by strain-induced replacement of albite (associated
dislocation glide and microfracturing) followed by growth and granular flow
simultaneous with dislocation creep of quartz are playing the dominating role
in formation of the mylonitic microstructure.</p
The direct evaluation of attosecond chirp from a streaking measurement
We derive an analytical expression, from classical electron trajectories in a
laser field, that relates the breadth of a streaked photoelectron spectrum to
the group-delay dispersion of an isolated attosecond pulse. Based on this
analytical expression, we introduce a simple, efficient and robust procedure to
instantly extract the attosecond pulse's chirp from the streaking measurement.Comment: 4 figure
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