Research collaboration in solar radiometry between the University of Reunion Island and the University of Kwazulu-Natal

Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.Since 2012, the Universities of KwaZulu-Natal and Reunion Island have collaborated on a joint programme of solar energy research. The initiative has two principle aims: the development of solar forecasting techniques and the expansion of solar monitoring capabilities from continental Africa into the southern Indian Ocean region. In this paper, we introduce the programme and review the progress made. A key activity is performance validation of a low-cost radiometric sensor, the Delta-T Devices SPN1, which has been operated at a UKZN ground station for comparison against reference sensors. The instrument potentially represents an opportunity to expand existing radiometric networks by reducing the cost of ground station facilities. A novel feature of the device is its use of seven thermopile sensors and a stationery shading mask which together enable the simultaneous measurement of global horizontal and diffuse horizontal irradiance. It is important that the instrument performance should first be assessed, however, so that its measurement uncertainty is known ahead of deployment. Data from the UKZN trial are included in the paper, along with a description of a meteorological classification system that may be used in solar forecasting systems. The system is based on the direct solar fraction, that is, the ratio of direct horizontal irradiance to global horizontal irradiance. A clustering methodology is described and sample data are provided to illustrate the ability of the method to segregate days into statistically significant bins.cf201

Technical design and characterization of a ground based solar metrology network on Reunion Island

Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.The roadmap of Reunion Island regarding energy is to reach autonomy by 2030. Obviously, renewable energies will play a key role in this ambitious project. However, a couple of years ago, a limit set by the French government relatively to the amount of lethal power injected on the electrical grid stopped the thrust: at any time, intermittent sources should not exceed 30 % of the whole production. This is due to the fragility of the grid: rugged topography, no interconnection. The University of La Reunion through the LE2P lab (Energy, Electronic and Process) decided to search a solution by predicting the solar resource in order to erase part of the intermittency of the production coming from the solar plants. Along this track, the first step is to evaluate precisely the resource and study its spatio-temporal variability. To do so, the LE2P gets engaged in deploying, at ground level, a network of monitoring stations. These units should be capable to produce field data responding to specific requirements in terms of acquisition frequency and quality, compatible with the clustering tools and mapping programs developed beside. Today, LE2P team manages a fleet of more than 15 stations, with various configurations, all over Reunion Island and plans to extend its network to neighboring territories. This article proposes to present in details the different components of a typical station, how they have been selected and how they are maintained. We will also see how the lab gets organized in order to propose top quality data to the solar scientific community.cf201

Technical design and characterization of a ground based solar metrology network on Reunion Island

Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.The roadmap of Reunion Island regarding energy is to reach autonomy by 2030. Obviously, renewable energies will play a key role in this ambitious project. However, a couple of years ago, a limit set by the French government relatively to the amount of lethal power injected on the electrical grid stopped the thrust: at any time, intermittent sources should not exceed 30 % of the whole production. This is due to the fragility of the grid: rugged topography, no interconnection. The University of La Reunion through the LE2P lab (Energy, Electronic and Process) decided to search a solution by predicting the solar resource in order to erase part of the intermittency of the production coming from the solar plants. Along this track, the first step is to evaluate precisely the resource and study its spatio-temporal variability. To do so, the LE2P gets engaged in deploying, at ground level, a network of monitoring stations. These units should be capable to produce field data responding to specific requirements in terms of acquisition frequency and quality, compatible with the clustering tools and mapping programs developed beside. Today, LE2P team manages a fleet of more than 15 stations, with various configurations, all over Reunion Island and plans to extend its network to neighboring territories. This article proposes to present in details the different components of a typical station, how they have been selected and how they are maintained. We will also see how the lab gets organized in order to propose top quality data to the solar scientific community.cf201

Role of N-terminal tau domain integrity on the survival of cerebellar granule neurons

Although the role of the microtubule-binding domain of the tau protein in the modulation of microtubule assembly is widely established, other possible functions of this protein have been poorly investigated. We have analyzed the effect of adenovirally mediated expression of two fragments of the N-terminal portion - free of microtubule-binding domain - of the tau protein in cerebellar granule neurons (CGNs). We found that while the expression of the tau (1-230) fragment, as well as of full-length tau, inhibits the onset of apoptosis, the tau (1-44) fragment exerts a powerful toxic action on the same neurons. The antiapoptotic action of tau (1-230) is exerted at the level of Akt-mediated activation of the caspase cascade. On the other hand, the toxic action of the (1-44) fragment is not prevented by inhibitors of CGN apoptosis, but is fully inhibited by NMDA receptor antagonists. These findings point to a novel, physiological role of the N-terminal domain of tau, but also underlay that its possible proteolytic truncation mediated by apoptotic proteases may generate a highly toxic fragment that could contribute to neuronal death

De novo mutations in GRIN1 cause extensive bilateral polymicrogyria

Polymicrogyria is a malformation of cortical development. The aetiology of polymicrogyria remains poorly understood. Using whole-exome sequencing we found de novo heterozygous missense GRIN1 mutations in 2 of 57 parent-offspring trios with polymicrogyria. We found nine further de novo missense GRIN1 mutations in additional cortical malformation patients. Shared features in the patients were extensive bilateral polymicrogyria associated with severe developmental delay, postnatal microcephaly, cortical visual impairment and intractable epilepsy. GRIN1 encodes GluN1, the essential subunit of the N-methyl-d-aspartate receptor. The polymicrogyria-associated GRIN1 mutations tended to cluster in the S2 region (part of the ligand-binding domain of GluN1) or the adjacent M3 helix. These regions are rarely mutated in the normal population or in GRIN1 patients without polymicrogyria. Using two-electrode and whole-cell voltage-clamp analysis, we showed that the polymicrogyria-associated GRIN1 mutations significantly alter the in vitro activity of the receptor. Three of the mutations increased agonist potency while one reduced proton inhibition of the receptor. These results are striking because previous GRIN1 mutations have generally caused loss of function, and because N-methyl-d-aspartate receptor agonists have been used for many years to generate animal models of polymicrogyria. Overall, our results expand the phenotypic spectrum associated with GRIN1 mutations and highlight the important role of N-methyl-d-aspartate receptor signalling in the pathogenesis of polymicrogyria