A conceptual analysis of approaches to rural development

Using Kenya as a case stndy, pragmatic dimensions of rural change are briefly discussed. Weaknesses are pointed out in the "directed change" approach to rural development and in the integrated, multi-dimensional approach. The criteria for a development from below strategy are presented which should help planners understand and effectively deal with the realities of the dynamism of rural development. Lastly, development from below in Kenya is reviewed through case study analysis of the Harambee self-help movement and an assessment of the current rural development efforts — the Special Rural Development Programme and the district planning strategy

Optimizing H1 cavities for the generation of entangled photon pairs

We report on the theoretical investigation of photonic crystal cavities etched on a suspended membrane for the generation of polarization entangled photon pairs using the biexciton cascade in a single quantum dot. The implementation of spontaneous emission enhancement effect increases the entanglement visibility, while the concomitant preferential funneling of the emission in the cavity mode increases the collection of both entangled photons. We demonstrate and quantify that standard cavity designs present a polarization dependent emission diagram, detrimental to entanglement. The optimization of H1 cavities allows to obtain both high collection efficiencies and polarization independent emission, while keeping high Purcell factors necessary for high quality entangled photon sources

Geomorphic response of submarine canyons to tectonic activity: Insights from the Cook Strait canyon system, New Zealand

Active margins host more than half of submarine canyons worldwide. Understanding the coupling between active tectonics and canyon processes is required to improve modeling of canyon evolution and derive tectonic information from canyon morphology. In this paper we analyze high-resolution geophysical data and imagery from the Cook Strait canyon system (CS), offshore New Zealand, to characterize the influence of active tectonics on the morphology, processes, and evolution of submarine canyons, and to deduce tectonic activity from canyon morphology. Canyon location and morphology bear the clearest evidence of tectonic activity, with major faults and structural ridges giving rise to sinuosity, steep and linear longitudinal profi les, cross-sectional asymmetry, and breaks in slope gradient, relief, and slope-area plots. Faults are also associated with stronger and more frequent sedimentary fl ows, steep canyon walls that promote gully erosion, and seismicity that is considered the most likely trigger of failure of canyon walls. Tectonic activity gives rise to two types of knickpoints in the CS. Gentle, rounded and diffusive knickpoints form due to short-wavelength folds or fault breakouts. The more widespread steep and angular knickpoints have migrated through canyonfloor slope failures and localized quarrying and/or plucking. Migration is driven by base-level lowering due to regional margin uplift and deepening of the lower Cook Strait Canyon, and is likely faster in larger canyons because of higher sedimentary flow throughput. The knickpoints, nonadherence to Playfair"s Law, linear longitudinal profiles, and lack of canyon-wide, inverse power law slope-area relationships indicate that the CS is in a transient state, adjusting to perturbations associated with tectonic displacements and changes in base level and sediment fluxes. We conclude by inferring unmapped faults and regions of more pronounced uplift, and proposing a generalized model for canyon geomorphic evolution in tectonically active margins

Visual ratings of atrophy in MCI: prediction of conversion and relationship with CSF biomarkers.

Medial temporal lobe atrophy (MTA) and cerebrospinal fluid (CSF) markers of Alzheimer's disease (AD) pathology may aid the early detection of AD in mild cognitive impairment (MCI). However, the relationship between structural and pathological markers is not well understood. Furthermore, while posterior atrophy (PA) is well recognized in AD, its value in predicting conversion from late-onset amnestic MCI to AD is unclear. In this study we used visual ratings of MTA and PA to assess their value in predicting conversion to AD in 394 MCI patients. The relationship of atrophy patterns with CSF Aβ1-42, tau, and p-tau(181) was further investigated in 114 controls, 192 MCI, and 99 AD patients. There was a strong association of MTA ratings with conversion to AD (p < 0.001), with a weaker association for PA ratings (p = 0.047). Specific associations between visual ratings and CSF biomarkers were found; MTA was associated with lower levels of Aβ1-42 in MCI, while PA was associated with elevated levels of tau in MCI and AD, which may reflect widespread neuronal loss including posterior regions. These findings suggest both that posterior atrophy may predict conversion to AD in late-onset MCI, and that there may be differential relationships between CSF biomarkers and regional atrophy patterns