Vision starts with the absorption of light by the retinal photoreceptors-cones and rods. However, due to the 'inverted' structure of the retina, the incident light must propagate through reflecting and scattering cellular layers before reaching the photoreceptors. It has been recently suggested that Muller cells function as optical fibres in the retina, transferring light illuminating the retinal surface onto the cone photoreceptors. Here we show that Muller cells are wavelength-dependent wave-guides, concentrating the green-red part of the visible spectrum onto cones and allowing the blue-purple part to leak onto nearby rods. This phenomenon is observed in the isolated retina and explained by a computational model, for the guinea pig and the human parafoveal retina. Therefore, light propagation by Muller cells through the retina can be considered as an integral part of the first step in the visual process, increasing photon absorption by cones while minimally affecting rod-mediated vision.

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Müller cells separate between wavelengths to improve day vision with minimal effect upon night vision

This report discusses the political, economic and social opportunities and constraints that will influence the design and implementation of REDD+ in Vietnam. In particular, four major direct drivers (land conversion for agriculture; infrastructure development; logging (illegal and legal); forest fire) and three indirect drivers (pressure of population growth and migration; the state's weak forest management capacity; the limited funding available for forest protection) of deforestation and degradation in Vietnam are discussed, along with their implications for REDD+. These drivers and their impacts vary from region to region, and change over time - no ‘one-size-fitsall' formula will function across the whole of Vietnam. The report also examines the lessons learnt from various forestry and economic development policies and programmes and suggests how a future REDD+ mechanism can overcome the major challenges, which include limited funding for forest protection, weak local governance capacity, poor vertical and horizontal coordination, low involvement of the poor, women and indigenous groups, low economic returns, elite capture of land and benefits, and corruption. The report suggests that if REDD+ is to succeed, it must be participatory, that is, all players are given fair and ample opportunity to be part of the programme (particularly those with the least resources or the greatest economic disenfranchisement); transparent, that is, all players can trace how the programme is administered, including the distribution of benefits; and well-monitored, to ensure that the programme is conducted such that it meets its overarching objectives and guidelines. The success of REDD+ will also require that it take a pro-poor and pro-gender equity approach.

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The context of REDD+ in Vietnam: drivers, agents and institutions.

Room acoustical parameters: A factor analysis approach

The distribution, accumulation, and ecological risk of heavy metals (Cu, Cd, Pb, Zn, Ni, Cr, and As) in the surface sediment were investigated in the upper reaches of Hunhe River, Northeast China. Sediment samples from 51 points throughout the upper reaches of Hunhe River were collected and measured for heavy metal concentrations, TN content, and TP content. Results showed that heavy metal concentrations at the vicinity of mines and towns were higher than those at other locations. According to sediment quality guidelines (SQGs), Cd and Zn were enriched in the sediments. The correlation analysis and principal component analysis (PCA) were conducted to assess the heavy metal sources. Close correlations between metal distribution and TP indicated that the sediments may be affected by application of phosphate fertilizer. Elements, Cu, Cd, Pb, Zn, and As, were grouped together, reflecting they were released from the same sources. PCA suggested that their primary sources were anthropogenic, namely mining and extensive use of fertilizers. Therefore, heavy metal pollution due to mining and agricultural intensification in the upper Hunhe River basin should be taken into account during the formation of regional management strategies for the water environment.

A. Marín

Papers

Analysis and assessment of concert halls

Model of energy calculation for acoustic analysis of closed rooms

Simulation of the piano as a musical source for the calculation of sound levels in closed rooms