6,008 research outputs found
Seismicity investigations in the Cascade Mountains and vicinity, Oregon, 1 May 1969 - 30 April 1970
Seismicity in Cascade Mountains and vicinity, Orego
The changing face of irrigation in Kenya: opportunities for anticipating changes in Eastern and Southern Africa
Small scale systems / Environmental effects / Government managed irrigation systems / Farmer managed irrigation systems / Health / Waterborne diseases / River basins / Pest control / Social impact / Water policy / Water law / Institutional development / Water allocation / Drip irrigation / Pumps / Technology / GIS / Databases / Irrigation programs / Drainage / Water resource management / Economic aspects / Social aspects / Water scarcity / Conflict / Case studies / Land management / Sedimentation / Flood control / Wetlands / Water quality / Erosion / Grassland management / Livestock / Rain / Drought / Participatory management / Design / Credit / Horticulture / Farmers’ associations / Farmers’ attitudes / Gender / Rice / Legislation / Land tenure / Cooperatives / Income / Southern Africa / Eastern Africa / Kenya / Upper Ewaso Ng’iro North Basin / Lake Victoria Basin / Tana River Basin / Mwea Irrigation Scheme
Hysteresis phenomenon in deterministic traffic flows
We study phase transitions of a system of particles on the one-dimensional
integer lattice moving with constant acceleration, with a collision law
respecting slower particles. This simple deterministic ``particle-hopping''
traffic flow model being a straightforward generalization to the well known
Nagel-Schreckenberg model covers also a more recent slow-to-start model as a
special case. The model has two distinct ergodic (unmixed) phases with two
critical values. When traffic density is below the lowest critical value, the
steady state of the model corresponds to the ``free-flowing'' (or ``gaseous'')
phase. When the density exceeds the second critical value the model produces
large, persistent, well-defined traffic jams, which correspond to the
``jammed'' (or ``liquid'') phase. Between the two critical values each of these
phases may take place, which can be interpreted as an ``overcooled gas'' phase
when a small perturbation can change drastically gas into liquid. Mathematical
analysis is accomplished in part by the exact derivation of the life-time of
individual traffic jams for a given configuration of particles.Comment: 22 pages, 6 figures, corrected and improved version, to appear in the
Journal of Statistical Physic
Preparation and properties of amorphous MgB/MgO superstructures: A new model disordered superconductor
In this paper we introduce a novel method for fabricating MgB/MgO
multilayers and demonstrate the potential for using them as a new model for
disordered superconductors. In this approach we control the annealing of the
MgB to yield an interesting new class of disordered (amorphous)
superconductors with relatively high transition temperatures. The multilayers
appear to exhibit quasi-two-dimensional superconductivity with controlled
anisotropy. We discuss the properties of the multilayers as the thickness of
the components of the bilayers vary.Comment: 7 pages, 8 figure
Critical thickness and orbital ordering in ultrathin La0.7Sr0.3MnO3 films
Detailed analysis of transport, magnetism and x-ray absorption spectroscopy
measurements on ultrathin La0.7Sr0.3MnO3 films with thicknesses from 3 to 70
unit cells resulted in the identification of a lower critical thickness for a
non-metallic, non-ferromagnetic layer at the interface with the SrTiO3 (001)
substrate of only 3 unit cells (~12 Angstrom). Furthermore, linear dichroism
measurements demonstrate the presence of a preferred (x2-y2) in-plane orbital
ordering for all layer thicknesses without any orbital reconstruction at the
interface. A crucial requirement for the accurate study of these ultrathin
films is a controlled growth process, offering the coexistence of
layer-by-layer growth and bulk-like magnetic/transport properties.Comment: 22 pages, 6 figures, accepted for publication in Physical Review
Admixtures to d-wave gap symmetry in untwinned YBa2Cu3O7 superconducting films measured by angle-resolved electron tunneling
We report on an \textit{ab}-anisotropy of and in
ramp-edge junctions between untwinned YBaCuO and % -wave
Nb. For these junctions, the angle with the YBaCuO
crystal b-axis is varied as a single parameter. The
A()-dependence presents 2-fold symmetry. The minima in
at suggest a real s-wave subdominant
component and negligible -wave or imaginary s-wave admixtures. The
()-dependence is well-fitted by 83% -, 15%
isotropic - and 2% anisotropic s-wave order parameter symmetry, consistent
with .Comment: 4 pages, 3 figures, to be published in Physical Review Letter
How much does teenage parenthood affect long term outcomes? A systematic review.
Background: The rates of teenage pregnancy in the UK are relatively high. Although early entry to parenthood can be a positive experience, most studies find large adverse effects on long term outcomes for the mother, child and father, in addition to being costly for the NHS. This is why the government launched its Teenage Pregnancy Strategy in 1999. However, there is growing evidence that teenage pregnancy might be mainly an indicator of disadvantage which is the underlying cause of the negative outcomes.
Methods: A systematic literature review was undertaken of studies which used a UK dataset to quantify any long term outcomes of a teenage birth upon the mother, father or child. Studies were included if they used appropriate methods to isolate the causal effect of early parenthood. The databases searched included Medline, Cochrane, EconLit and Web of Science.
Results: Six studies were identified by the review; five studies considered the mother’s socioeconomic outcomes, one study reported the child’s outcomes, and no studies met the inclusion criteria for the father’s outcomes. The studies suggested that early motherhood accounts for relatively few of the negative long term socioeconomic outcomes and it is predominantly an indicator of a disadvantaged family background.
Conclusion: Limited evidence is available to understand the long term outcomes associated with teenage birth within the UK for the mother, father and child. Current econometric studies suggest that effective interventions to prevent teenage pregnancies will not eradicate the poorer long term socioeconomic outcomes often associated with early motherhood. Thus policy should focus on reducing initial disadvantage in addition to preventing teenage pregnancy. Additional econometric analyses around the mothers’, fathers’ and children’s long term socioeconomic and health-related outcomes would be
valuable
Sharp interface limit for a phase field model in structural optimization
We formulate a general shape and topology optimization problem in structural
optimization by using a phase field approach. This problem is considered in
view of well-posedness and we derive optimality conditions. We relate the
diffuse interface problem to a perimeter penalized sharp interface shape
optimization problem in the sense of -convergence of the reduced
objective functional. Additionally, convergence of the equations of the first
variation can be shown. The limit equations can also be derived directly from
the problem in the sharp interface setting. Numerical computations demonstrate
that the approach can be applied for complex structural optimization problems
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