Dehydration mechanism of a small molecular solid: 5-nitrouracil hydrate

Previous studies of the dehydration of 5-nitrouracil (5NU) have resulted in it being classified as a ‘‘channel hydrate’’ in which dehydration proceeds principally by the exit of the water molecules along channels in the structure. We have re-examined this proposal and found that in fact there are no continuous channels in the 5NU structure that would contribute to such a mechanism. Product water molecules would be immediately trapped in unlinked voids in the crystal structure and would require some additional mechanism to break loose from the crystal. Through a detailed structural analysis of the macro and micro structure of the 5NU as it dehydrates, we have developed a model for the dehydration process based on the observed development of structural defects in the 5NU crystal and the basic crystallography of the material. The model was tested against standard kinetic measurements and found to present a satisfactory account of kinetic observations, thus defining the mechanism. Overall, the study shows the necessity of complementing standard kinetic studies with a parallel macro and micro examination of the dehydrating material when evaluating the mechanisms of dehydration and decomposition processes

Media Practitioners and Public Opinions on Interactive Broadcast TV Shows in Africa: Citizen TV (Kenya) and Muvi TV (Zambia)

Interactive TV and radio shows are popular phenomena in Kenya and Zambia. Drawing primarily from interview and observation based research in TV stations in Kenya and Zambia, this paper examines the role of media practitioners in shaping interactive broadcast programmes, and the nature and possibilities of audience participation. Looking at the cases of Muvi TV’s The Assignment in Zambia and Power Breakfast and Cheche on Kenya’s Citizen TV, it considers the agency of the host and presenter of interactive shows. This working paper analyses the various ways that hosts implement ground rules for appropriate behaviour of audience members and seek to create space for different voices. It then turns to analyse the constraining e ects of the wider political and regulatory environment in the two countries, for instance, Zambia as a ‘Christian nation’ and a relatively peaceful country, and Kenya as a ‘volatile nation’ due to insecurity, including terrorism-related threats and ethnic tensions. In so doing, this paper finds that despite structural factors and individual limitations, the hosts of these shows see themselves, and have been seen by audiences, guests and political elites, as key drivers and celebrities that shape access and nature of participation

Media Practitioners and Public Opinions on Interactive Broadcast TV Shows in Africa: Citizen TV (Kenya) and Muvi TV (Zambia)

Interactive TV and radio shows are popular phenomena in Kenya and Zambia. Drawing primarily from interview and observation based research in TV stations in Kenya and Zambia, this paper examines the role of media practitioners in shaping interactive broadcast programmes, and the nature and possibilities of audience participation. Looking at the cases of Muvi TV’s The Assignment in Zambia and Power Breakfast and Cheche on Kenya’s Citizen TV, it considers the agency of the host and presenter of interactive shows. This working paper analyses the various ways that hosts implement ground rules for appropriate behaviour of audience members and seek to create space for different voices. It then turns to analyse the constraining e ects of the wider political and regulatory environment in the two countries, for instance, Zambia as a ‘Christian nation’ and a relatively peaceful country, and Kenya as a ‘volatile nation’ due to insecurity, including terrorism-related threats and ethnic tensions. In so doing, this paper finds that despite structural factors and individual limitations, the hosts of these shows see themselves, and have been seen by audiences, guests and political elites, as key drivers and celebrities that shape access and nature of participation

Seeded and unseeded high order parametric down conversion

Spontaneous parametric down conversion (SPDC) has been one of the foremost tools in quantum optics for over five decades. Over that time it has been used to demonstrate some of the curious features that arise from quantum mechanics. Despite the success of SPDC, its higher-order analogues have never been observed, even though it has been suggested that they generate far more unique and exotic states than SPDC. An example of this is the emergence of non-Gaussian states without the need for post-selection. Here we calculate the expected rate of emission for nth-order SPDC with and without external stimulation (seeding). Focusing primarily on third-order parametric down-conversion (TOPDC), we estimate the photon detection rates in a rutile crystal, for both the unseeded and seeded regimes.Comment: 11 pages, 6 figure

Functional soil property maps are just a click away

With data provided by the Africa Soil Information Service (AfSIS), farmers, agricultural experts, and natural resource managers will be able to identify the best options for sustainably improving crop production and better managing the land, including contributing to better ecosystem services management at regional, national, and local levels. The AfSIS project involves probing the landscape of sub-Saharan Africa, using a variety of highly accurate digital soil mapping techniques including remote sensing, infrared and x-ray spectroscopy scanning techniques, to create detailed soil maps. The data generated will also allow climatic change prediction with soil as a major input into the modeling. Launched in January 2009, and using 60 randomly selected 10 x 10 km sampling locations to characterize the soils, the AfSIS project has completed 25 of the 60 projected sampling locations making the objective of completing the remaining 35 locations feasible by October 2012. Countries so far sampled include Tanzania, Ethiopia, Malawi, Mozambique, South Africa, Ghana, Mali, and Nigeria. The information generated so far is now freely available from AfSIS website: www.africasoils

Background Paper: Politics and Interactive Media in Kenya

The PiMA Working Papers are a series of peer-reviewed working papers that present findings and insights from Centre of Governance and Human Rights’ (CGHR) Politics and Interactive Media in Africa (PiMA) research project (2012-14). The project, jointly funded by the ESRC and DFID (ES/J018945/1), focuses on expressions of ‘public opinion’ in broadcast media via new information and communication technologies (ICT) such as mobile phones in Kenya and Zambia. PiMA examines the political implications of such interactions in the two African countries, with a view to drawing conclusions of wider significance to practitioners and policymakers. Series Editors: Sharath Srinivasan, Stephanie DiepeveenThis background paper provides an overview of the history and context of interactive media and public opinion in Kenya. It is intended to contextualise and inform the study, Politics and Interactive Media in Africa (PiMA), a collaborative study by researchers from the University of Cambridge, University of Nairobi and University of Zambia. The main objectives of the PiMA project are: (a) to explore the extent to which media interactivity is widening (and deepening) political participation in Africa; (b) to investigate how public opinion is collected and represented by African media and for what (and whose) purposes; and (c) to establish the extent to which public opinion expressed via interactive media affects accountability mechanisms and policy-makers’ behaviour. This working paper is organised into three sections. The first section discusses the policy and legal context for interactive media in Kenya. The second section discusses the history of broadcast media and interactive shows. The final section examines the intersection of public opinion and interactive media in Kenya.PiMA was jointly funded by the ESRC and DFID (ES/J018945/1

Biocontrol of Aspergillus and Fusarium Mycotoxins in Africa : benefits and limitations

Fungal contamination and the consequent mycotoxin production is a hindrance to food and feed safety, international trade and human and animal health. In Africa, fungal contamination by Fusarium and Aspergillus is heightened by tropical climatic conditions that create a suitable environment for pre- and postharvest mycotoxin production. The biocontrol of Fusarium and its associated fusariotoxins has stagnated at laboratory and experimental levels with species of Trichoderma, Bacillus and atoxigenic Fusarium being tested as the most promising candidates. Hitherto, there is no impetus to upscale for field use owing to the inconsistent results of these agents. Non-aflatoxigenic strains of Aspergillus have been developed to create biocontrol formulations by outcompeting the aflatoxigenic strains, thus thwarting aflatoxins on the target produce by 70% to 90%. Questions have been raised on their ability to produce other mycotoxins like cyclopiazonic acid, to potentially exchange genetic material and to become aflatoxigenic with consequent deleterious effects on other organisms and environments. Other biocontrol approaches to mitigate aflatoxins include the use of lactic acid bacteria and yeast species which have demonstrated the ability to prevent the growth of Aspergillus flavus and consequent toxin production under laboratory conditions. Nevertheless, these strategies seem to be ineffective under field conditions. The efficacy of biological agents is normally dependent on environmental factors, formulations' safety to non-target hosts and the ecological impact. Biocontrol agents can only be effectively evaluated after long-term use, causing a never-ending debate on the use of live organisms as a remedy to pests and diseases over the use of chemicals. Biocontrol should be used in conjunction with good agricultural practices coupled with good postharvest management to significantly reduce mycotoxins in the African continent

Cytokine expression in malaria-infected non-human primate placentas

Malaria parasites are known to mediate the induction of inflammatory immune responses at the maternal-foetal interface during placental malaria (PM) leading to adverse consequences like pre-term deliveries and abortions. Immunological events that take place within the malaria-infected placental micro-environment leading to retarded foetal growth and disruption of pregnancies are among the critical parameters that are still in need of further elucidation. The establishment of more animal models for studying placental malaria can provide novel ways of circumventing problems experienced during placental malaria research in humans such as inaccurate estimation of gestational ages. Using the newly established olive baboon (Papio anubis)-Plasmodium knowlesi (P. knowlesi) H strain model of placental malaria, experiments were carried out to determine placental cytokine profiles underlying the immunopathogenesis of placental malaria. Four pregnant olive baboons were infected with blood stage P. knowlesi H strain parasites on the one fiftieth day of gestation while four other uninfected pregnant olive baboons were maintained as uninfected controls. After nine days of infection, placentas were extracted from all the eight baboons through cesarean surgery and used for the processing of placental plasma and sera samples for cytokine sandwich enzyme linked immunosorbent assays (ELISA). Results indicated that the occurrence of placental malaria was associated with elevated concentrations of tumour necrosis factor alpha (TNF-{\alpha}) and interleukin 12 (IL-12). Increased levels of IL-4, IL-6 and IL-10 and interferon gamma (IFN-{\gamma}) levels were detected in uninfected placentas. These findings match previous reports regarding immunity during PM thereby demonstrating the reliability of the olive baboon-P. knowlesi model for use in further studies.Comment: Open Veterinary Journal 1st June 2012. Seven pages, Three Figures. arXiv admin note: text overlap with arXiv:1201.323