On the normality of Higgins commutators

In a semi-abelian context, we study the condition (NH) asking that Higgins commutators of normal subobjects are normal subobjects. We provide examples of categories that do or do not satisfy this property. We focus on the relationship with the "Smith is Huq" condition (SH) and characterise those semi-abelian categories in which both (NH) and (SH) hold in terms of reflection and preservation properties of the change of base functors of the fibration of points.Comment: 15 pages; final published versio

Breeding drought tolerant cowpea: constraints, accomplishments, and future prospects

This review presents an overview of accomplishments on different aspects of cowpea breeding for drought tolerance. Furthermore it provides options to enhance the genetic potential of the crop by minimizing yield loss due to drought stress. Recent efforts have focused on the genetic dissection of drought tolerance through identification of markers defining quantitative trait loci (QTL) with effects on specific traits related to drought tolerance. Others have studied the relationship of the drought response and yield components, morphological traits and physiological parameters. To our knowledge, QTLs with effects on drought tolerance have not yet been identified in cowpea. The main reason is that very few researchers are working on drought tolerance in cowpea. Some other reasons might be related to the complex nature of the drought stress response, and partly to the difficulties associated with reliable and reproducible measurements of a single trait linked to specific molecular markers to be used for marker assisted breeding. Despite the fact that extensive research has been conducted on the screening aspects for drought tolerance in cowpea only very few¿like the `wooden box¿ technique¿have been successfully used to select parental genotypes exhibiting different mechanisms of drought tolerance. Field and pot testing of these genotypes demonstrated a close correspondence between drought tolerance at seedling and reproductive stages. Some researchers selected a variety of candidate genes and used differential screening methods to identify cDNAs from genes that may underlie different drought tolerance pathways in cowpea. Reverse genetic analysis still needs to be done to confirm the functions of these genes in cowpea. Understanding the genetics of drought tolerance and identification of DNA markers linked to QTLs, with a clear path towards localizing chromosomal regions or candidate genes involved in drought tolerance will help cowpea breeders to develop improved varieties that combine drought tolerance with other desired traits using marker assisted selection

Climate change risk perceptions of audiences in the climate change blogosphere

The Climate Change Risk Perception Model (CCRPM, Van der Linden, 2015) has been used to characterize public risk perceptions; however, little is known about the model’s explanatory power in other (online) contexts. In this study, we extend the model and investigate the risk perceptions of a unique audience: The polarized climate change blogosphere. In total, our model explained 84% of the variance in risk perceptions by integrating socio-demographic characteristics, cognitive factors, experiential processes, socio-cultural influences, and an additional dimension: Trust in scientists and blogs. Although trust and the scientific consensus are useful additions to the model, affect remains the most important predictor of climate change risk perceptions. Surprisingly, the relative importance of social norms and value orientations is minimal. Implications for risk and science communication are discussed.</jats:p

Influence of water layer thickness on crater volume for nanosecond pulsed laser ablation of stainless steel

Under water laser ablation is a surface texturization method used to form micrometer-sized surface structures. Plasma confinement and cavitation bubble evolution play a critical role during the ablation process and their influence on material removal is strongly tied to liquid layer thickness. To influence the effects of these processes, such that material removal is at its maximum, an optimal layer thickness was found for various laser parameters. Specifically, for nanosecond pulsed laser ablation of stainless steel, however, the relation between layer thickness and volume removal is still unknown. Here, we show the relation between water layer thickness and removed material volume for a nanosecond pulsed laser. Results reveal that volume removal is at its maximum for a 1 mm water layer and drops by a factor of 2 when the layer thickness is increased to 2 mm. A further increase of layer thickness to 3 up to 10 mm shows a negligible effect on volume removal and removed volume amounts are shown to be similar to those obtained in ambient air in this water layer thickness range. This trend echo’s results obtained for nanosecond pulsed silicon ablation. The obtained results identify processing conditions which allow for faster and therefore more cost efficient texturization of stainless steel surfaces in the future.</p

Feasibility and effectiveness of combination antiretroviral therapy in HIV-infected infants in Pietermaritzburg, South Africa

Background : In the absence of treatment, 50% of HIV-infected children will die before 2 years of age. In a recent randomized controlled trial, a 76% decrease in mortality was observed in infants receiving early combination antiretroviral therapy [1]. The World Health Organization now recommends starting all HIV-infected infants on combination antiretroviral therapy on diagnosis [2]. However, few data are available outside a well-controlled research setting. Purpose of the study : To show the feasibility and effectiveness of treating HIV-infected infants in a state-funded clinic located in a poorly resourced South African township. Methods : A retrospective chart review was performed of all HIV-1 infected infants initiated on combination antiretroviral therapy (cART) between 1st May 2005 and 31st May 2008 at the Edendale Family Clinic, Pietermaritzburg, South Africa. All HIV-1 infected infants who were less than 1 year of age when antiretroviral therapy was initiated, and who had completed at least 6 months of treatment, were included. Weight for age Z scores, CD4 %, viral loads (VL) and haemoglobin were collected on initiation of treatment and at 6-monthly intervals thereafter. Virological success was defined as VL25%. Z scores were analyzed using Epi-Info. Summary of results : Of 129 treated infants, 94 completed 6 months of cART; 60 completed 12 months and 39 completed 18 months of treatment. Mean age at initiation was 8 months (range 2.1-11.7). 77.2% had advanced disease (WHO Stage 3 or 4). The infants were severely malnourished, with a mean Z-score of -2.4 (range -6.1 - +0.8). Mean baseline VL was 4700 000 copies/ml. After 6 months of treatment, 52.3% of babies had an undetectable VL, with 75% having a VL of < 400 copies/ml. Viral suppression was achieved in 34 (56.9%) out of the 60 infants who completed 1 year of cART and 79.3% had a VL <400 copies/ml. Undetectable VL was found in 78.8% of the 39 children who received 18 months of treatment. Weight for age Z score increased from a mean of -2.4 (<3rd centile) at initiation of treatment to -0.3 (38th centile) for the children who received 18 months of cART. The CD4% increased from a mean of 16.5% at the start to 31.9% at 18 months. Conclusions : This study from a township in Kwazulu-Natal shows a good clinical, immunological and virological response to cART in HIV-infected infants, despite high baseline viral loads and advanced disease