Simulation of gain stability of THGEM gas-avalanche particle detectors

Charging-up processes affecting gain stability in Thick Gas Electron Multipliers (THGEM) were studied with a dedicated simulation toolkit. Integrated with Garfield++, it provides an effective platform for systematic phenomenological studies of charging-up processes in MPGD detectors. We describe the simulation tool and the fine-tuning of the step-size required for the algorithm convergence, in relation to physical parameters. Simulation results of gain stability over time in THGEM detectors are presented, exploring the role of electrode-thickness and applied voltage on its evolution. The results show that the total amount of irradiated charge through electrode's hole needed for reaching gain stabilization is in the range of tens to hundreds of pC, depending on the detector geometry and operational voltage. These results are in agreement with experimental observations presented previously

Household water security through stored rainwater and consumer acceptability: a case study of the Anuradhapura District

Rainwater harvesting has increased in popularity in Sri Lanka over the past two decades due to the number of water supply projects funded by the government and non-governmental organizations (NGOs). The stored rainwater can provide accessible, reliable, timely and adequate supplies of water to households but there are uncertainties as to safety, in terms of water quality, and consumer acceptability. A study was, therefore, conducted in the Anuradhapura District, in the dry zone, to assess consumer acceptability of stored rainwater for household purposes and to conduct rainwater quality tests in a laboratory. The majority of households in Anuradhapura meet their drinking water requirements from protected wells (59.6 %). Prior to the project, people greatly preferred open wells as a source of domestic water, followed by tubewells, because they believed that water in open wells is of good quality and drinkable. However, stored rainwater has become the priority source now, especially through roof rainwater harvesting (RRWH), which is used during the dry periods. The study revealed that more than 85 % of households use stored rainwater for drinking although some have concerns over the quality and only drink it after boiling. The easy accessibility of water and the assurance by the project team that it is of good quality are the main reasons that people are willing to drink it. The acceptability of stored rainwater for consumption was very high in water-scarce areas and with the increasing distance to the nearest and alternative sources of good-quality water. Of those who felt that they had adequate water, 84 % of the sample households found it adequate in the wet season but only 21 % in the dry season. Water quality analysis revealed that the chemical and physical quality of stored rainwater is within the acceptable range with respect to Sri Lankan Standards, SLS: 614, for potable water quality (SLIS 1983). Other domestic water sources exceeded standards for electrical conductivity, total alkalinity, hardness, ammonium nitrogen, fluorides and total iron. However, stored rainwater was of lower biological quality than other domestic water sources.Length: pp.87-97Domestic waterWater securityWater harvestingWater qualityRural areasCase studies

Differential expression of dormancy-associated genes in fastigiata and hypogaea peanut.

Seed dormancy is a temporary replacement state observed in some higher plants, which prevents germination under unfavorable conditions. In several species, dormancy process is triggered by hormonal factors, initiated by ABA and precursor enzymes. In this work, we investigated the relationship between dormancy and the expression of ARP, DMR1, and NCED genes in upright and runner peanut seeds. Eight dormancy-contrasting genotypes were previously phenotyped based on germination traits, during three storage periods. Expression of ARP, DMR1 and NCED transcripts was analyzed by qRT-PCR, from endosperm and embryo tissues. Higher expression of NCED and ARP were found in embryo tissues from runner genotypes, IAC Caiapo and LGoPE-06, confirming findings in literature as to association of these genes with seed dormancy. Higher expression of DMR1 was found only in endosperm of upright materials (L7 Bege and BR1). We suggest the NCED is a functional molecular marker to identify dormancy in seeds, contributing to selection procedures of runner genotypes in peanut breeding