Production of Lambda and Sigma^0 hyperons in proton-proton collisions

This paper reports results on simultaneous measurements of the reaction channels pp -> pK+\Lambda and pp -> pK+\Sigma^0 at excess energies of 204, 239, and 284 MeV (\Lambda) and 127, 162, and 207 MeV (\Sigma^0). Total and differential cross sections are given for both reactions. It is concluded from the measured total cross sections that the high energy limit of the cross section ratio is almost reached at an excess energy of only about 200 MeV. From the differential distributions observed in the overall CMS as well as in the Jackson and helicity frames, a significant contribution of interfering nucleon resonances to the \Lambda production mechanism is concluded while resonant \Sigma^0-production seems to be of lesser importance and takes place only through specific partial waves of the entrance channel. The data also indicate that kaon exchange plays a minor role in the case of \Lambda- but an important role for \Sigma^0-production. Thus the peculiar energy dependence of the \Lambda-to-\Sigma^0 cross section ratio appears in a new light as its explanation requires more than mere differences between the p\Lambda and the p\Sigma^0 final state interaction. The data provide a benchmark for theoretical models already available or yet to come.Comment: 18 pages, 10 figures; accepted by The European Physical Journal A (EPJ A

Seawater intrusion caused by unmanaged groundwater uses in a coastal tourist area, Cox's Bazar, Bangladesh

The Cox's Bazar region at the southeastern coast of Bangladesh has been gradually changed from a rural settlement into a densely populated urban area, caused by the rapid growth of tourism. Water demand is mainly covered by groundwater, and the hotels and resorts are typically operating their own groundwater wells without metering and regulations. In this study, the temporal and spatial variations in groundwater quality and hydraulic heads in the Cox's Bazar area were evaluated over a period of 2 and 4 years respectively, to analyze the effects of the groundwater extractions on the status of the groundwater resources. Due to the pronounced seasonality of rainfall, the aquifer system was found to be highly dynamic even without human interference and seawater intrusion into the aquifers from the Bay of Bengal as well as from the Bakkhali river in the north was detected. The groundwater abstraction caused groundwater levels in some touristic centers to be already per-manently below sea level, and a trend to a further lowering of hydraulic heads was observed. This coincides with an overall trend of increasing electrical conductivities in the groundwater. For a sound and sustainable development of the Cox's Bazar region, water management strategies and a regulatory framework have to be developed that consider the specific conditions in such a coastal zone

Biology and behaviour of male mosquitoes in relation to new approaches to control disease transmitting mosquitoes

The enormous burden placed on populations worldwide by mosquito-borne diseases, most notably malaria and dengue, is currently being tackled by the use of insecticides sprayed in residences or applied to bednets, and in the case of dengue vectors through reduction of larval breeding sites or larviciding with insecticides thereof. However, these methods are under threat from, amongst other issues, the development of insecticide resistance and the practical difficulty of maintaining long-term community-wide efforts. The sterile insect technique (SIT), whose success hinges on having a good understanding of the biology and behaviour of the male mosquito, is an additional weapon in the limited arsenal against mosquito vectors. The successful production and release of sterile males, which is the mechanism of population suppression by SIT, relies on the release of mass-reared sterile males able to confer sterility in the target population by mating with wild females. A five year Joint FAO/IAEA Coordinated Research Project brought together researchers from around the world to investigate the pre-mating conditions of male mosquitoes (physiology and behaviour, resource acquisition and allocation, and dispersal), the mosquito mating systems and the contribution of molecular or chemical approaches to the understanding of male mosquito mating behaviour. A summary of the existing knowledge and the main novel findings of this group is reviewed here, and further presented in the reviews and research articles that form this Acta Tropica special issue

Using consultative methods to investigate professional–client interaction as an aspect of process evaluation

This article is not available through ChesterRep.This article discusses a consultative method called reconstitutive ethnography, which is considered useful for the in-depth description and analysis of the interaction between a professional and client in the delivery of a health or social care program.This article was submitted to the RAE2008 for the University of Chester - Social Work and Social Policy & Administration