28,406 research outputs found
Facilitating Seed Sector Transformation in Africa: Key Findings from the Literature
Crop Production/Industries, Downloads July 2008 - July 2009: 9,
Brittle extension of the continental crust along a rooted system of low-angle normal faults: Colorado River extensional corridor
A transect across the 100 km wide Colorado River extensional corridor of mid-Tertiary age shows that the upper 10 to 15 km of crystalline crust extended along an imbricate system of brittle low-angle normal faults. The faults cut gently down a section in the NE-direction of tectonic transport from a headwall breakaway in the Old Woman Mountains, California. Successively higher allochthons above a basal detachment fault are futher displaced from the headwall, some as much as tens of kilometers. Allochthonous blocks are tilted toward the headwall as evidenced by the dip of the cappoing Tertiary strata and originally horizontal Proterozoic diabase sheets. On the down-dip side of the corridor in Arizona, the faults root under the unbroken Hualapai Mountains and the Colorado Plateau. Slip on faults at all exposed levels of the crust was unidirectional. Brittle thinning above these faults affected the entire upper crust, and wholly removed it locally along the central corridor or core complex region. Isostatic uplift exposed metamorphic core complexes in the domed footwall. These data support a model that the crust in California moved out from under Arizona along an asymmetric, rooted normal-slip shear system. Ductile deformation must have accompanied mid-Tertiary crustal extension at deeper structural levels in Arizona
Method for detecting surface motions and mapping small terrestrial or planetary surface deformations with synthetic aperture radar
A technique based on synthetic aperture radar (SAR) interferometry is used to measure very small (1 cm or less) surface deformations with good resolution (10 m) over large areas (50 km). It can be used for accurate measurements of many geophysical phenomena, including swelling and buckling in fault zones, residual, vertical and lateral displacements from seismic events, and prevolcanic swelling. Two SAR images are made of a scene by two spaced antennas and a difference interferogram of the scene is made. After unwrapping phases of pixels of the difference interferogram, surface motion or deformation changes of the surface are observed. A second interferogram of the same scene is made from a different pair of images, at least one of which is made after some elapsed time. The second interferogram is then compared with the first interferogram to detect changes in line of sight position of pixels. By resolving line of sight observations into their vector components in other sets of interferograms along at least one other direction, lateral motions may be recovered in their entirety. Since in general, the SAR images are made from flight tracks that are separated, it is not possible to distinguish surface changes from the parallax caused by topography. However, a third image may be used to remove the topography and leave only the surface changes
Geology of Hadley Rille
The regional setting, external and internal shape, and materials of Hadley Rille near the Apollo 15 landing site are described. The petrography presented includes lithologies, regolith, talus, and outcrops. The stratigraphy exposed on the rille wall is also considered
No Shortcuts to Progress: An Assessment of Agricultural Research Planning and Priority Setting in Africa
Research and Development/Tech Change/Emerging Technologies, Downloads July 2008-June 2009: 7,
Seed Sector Evolution in Zambia and Zimbabwe: Has Farmer Access Improved Following Economic Reforms?
Crop Production/Industries, Downloads July 2008-June 2009: 19,
Non-equilibrium fluctuations and mechanochemical couplings of a molecular motor
We investigate theoretically the violations of Einstein and Onsager
relations, and the efficiency for a single processive motor operating far from
equilibrium using an extension of the two-state model introduced by Kafri {\em
et al.} [Biophys. J. {\bf 86}, 3373 (2004)]. With the aid of the Fluctuation
Theorem, we analyze the general features of these violations and this
efficiency and link them to mechanochemical couplings of motors. In particular,
an analysis of the experimental data of kinesin using our framework leads to
interesting predictions that may serve as a guide for future experiments.Comment: 4 pages, 4 figures, accepted to Phys. Rev. Let
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Correlated modal mineralogy, aqueous alteration and oxygen isotope composition of CM Chondrites
In this study we move beyond defining alteration sequences in CM chondrites towards understanding the relationship between modal mineralogy, the extent of aqueous alteration and O-isotope compositions
Can The Momentum be Sustained? An Economic Analysis of the Ministry of Agriculture/Sasakawa Global 2000's Experiment with Improved Cereals Technology in Ethiopia
A Joint Research Activity of: Grain Marketing Research Project/Michigan State University, Sasakawa Global 2000, Ministry of Agriculture Department of Extension and Cooperatives, Ethiopian Agricultural Research Organizationfood security, food policy, Ethiopia, SG2000, Crop Production/Industries, Q18,
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