From "best practice" to "best fit": a framework for designing and analyzing pluralistic agricultural advisory services

"Agricultural advisory services play an important role in supporting the use of the agricultural sector as an engine of pro-poor growth and enabling small farmers to meet new challenges, such as accessing export markets, adopting environmentally sustainable production techniques, and coping with HIV/AIDS and other health challenges that affect agriculture...There is now renewed interest in agricultural advisory services in many countries.... The questions under debate include: What should be the roles of the public sector, private sector, and civil society? How can we ensure that agricultural advisory services are demand-driven and meet the diverse information needs of farmers? How can advisory services be made efficient and financially sustainable? How can we ensure that female farmers, the poor, and other marginalized groups have access to agricultural advisory services?" from Authors' SummaryAgricultural extension work, Pro-poor growth, Capacity strengthening,

Agrobacterium tumefaciens-mediated transformation of Pseudocercospora fijiensis to determine the role of PfHog1 in osmotic stress regulation and virulence modulation

Open Access Journal; Published online: 16 May 2017Black Sigatoka disease, caused by Pseudocercospora fijiensis is a serious constraint to banana production worldwide. The disease continues to spread in new ecological niches and there is an urgent need to develop strategies for its control. The high osmolarity glycerol (HOG) pathway in Saccharomyces cerevisiae is well known to respond to changes in external osmolarity. HOG pathway activation leads to phosphorylation, activation and nuclear transduction of the HOG1 mitogen-activated protein kinases (MAPKs). The activated HOG1 triggers several responses to osmotic stress, including up or down regulation of different genes, regulation of protein translation, adjustments to cell cycle progression and synthesis of osmolyte glycerol. This study investigated the role of the MAPK-encoding PfHog1 gene on osmotic stress adaptation and virulence of P. fijiensis. RNA interference-mediated gene silencing of PfHog1 significantly suppressed growth of P. fijiensis on potato dextrose agar media supplemented with 1 M NaCl, indicating that PfHog1 regulates osmotic stress. In addition, virulence of the PfHog1-silenced mutants of P. fijiensis on banana was significantly reduced, as observed from the low rates of necrosis and disease development on the infected leaves. Staining with lacto phenol cotton blue further confirmed the impaired mycelial growth of the PfHog1 in the infected leaf tissues, which was further confirmed with quantification of the fungal biomass using absolute- quantitative PCR. Collectively, these findings demonstrate that PfHog1 plays a critical role in osmotic stress regulation and virulence of P. fijiensis on its host banana. Thus, PfHog1 could be an interesting target for the control of black Sigatoka disease in banana

Effect of humidification of reactive gases on the performance of a proton exchange membrane fuel cell

This work studies the impact of water formation on the performance of Proton Exchange Membrane Fuel Cells (PEMFCs). The work examines water management in PEM fuel cells both experimentally and theoretically.Experiments are conducted using a one stack PEM fuel cell fitted with Nafion membrane to evaluate its performance using both dry and humidified hydrogen and air. Results obtained confirms the importance of fuel humidification in improving the performance of the fuel cell with all levels of humidification producing better performance than that obtained using dry hydrogen or dry air. Experiments using air with 50% relative humidity indicate drop in the fuel cell performance when comparing the results to those from air with 100% relative humidity.The experimental data provides the basis to validate a computation fluid dynamics model for the fuel cell that is used to carry out further studies and conduct a parametric analysis of the fuel cell performance to examine the effects of flow plates designs, flow patterns such as parallel and counter flow and level of humidification on membrane water saturation, flooding, water management, reactants concentrations and overall cell performance by observing parameters such as membrane protonic conductivity, current density, cell voltage and power.The CFD model studies and compares the use of air and oxygen in PEM fuel cells and the results show that for 100% relative humidity the performance obtained using pure oxygen is only marginally better than the one obtained when using air. This indicates that it is more beneficial to use air at the right conditions in PEM fuel cells given the cost of pure oxygen as the overall economic balance and the ease of use favour the utilisation of air

The effect of temperature on CO2 injectivity in sandstone reservoirs

Carbon Capture, Utilization and Storage (CCUS) is a pragmatic technology that could reduce anthropogenic CO2 and halt climate change. CO2 injectivity is affected by several physicochemical interactions around the injection area of the wellbore which are temperature-dependant. There is a thermal disequilibrium between the injected CO2 and the reservoir rock at the wellbore injection area which has not been thoroughly investigated. A pore-scale model was developed to predict the distance travelled by the injected fluid into the formation before thermal equilibrium is established. In the Snøhvit field where the wellhead injection temperature is 4 °C, it was found that the injected CO2 may attain supercritical state at bottomhole conditions, although a minimum temperature difference of about 40 °C may exist between the bottomhole fluid and the reservoir rock. Thermal equilibrium around the injection area was dependant on the wellhead injection temperature, the injection flow rate and reservoir shaliness.publishedVersio

Experimental and analytical study of open pore cellular foam material on the performance of proton exchange membrane electrolysers

The aim of this research is to develop research methodology and provide insight into the viability of using Open Pore Cellular Foam (OPCF) material in Polymer Electrolyte Membrane (PEM) Electrolysers. Analysis have therefore been carried out on three different types of electrolyser geometries. A PEM electrolyser is considered with serpentine, mesh and OPCF flow channels, whilst all the other physical and operational parameters are kept constant. Three dimensional models have been created in solid works and computational fluid dynamic simulations have been carried out on all the three types of electrolysers in ANSYS Fluent. Experimental investigations have also been carried out using all the three different flow plate geometries. ANSYS simulation show that the performance of the OPCF flow channel electrolyser is 1.5 times higher than that of the mesh channel electrolyser. Experimental results have shown that using OPCF flow channel the performance of the electrolyser improves significantly by 17% to that compared with conventional mesh flow plate electrolysers

The effects of integrated care: a systematic review of UK and international evidence

BACKGROUND: Healthcare systems around the world have been responding to the demand for better integrated models of service delivery. However, there is a need for further clarity regarding the effects of these new models of integration, and exploration regarding whether models introduced in other care systems may achieve similar outcomes in a UK national health service context. METHODS: The study aimed to carry out a systematic review of the effects of integration or co-ordination between healthcare services, or between health and social care on service delivery outcomes including effectiveness, efficiency and quality of care. Electronic databases including MEDLINE; Embase; PsycINFO; CINAHL; Science and Social Science Citation Indices; and the Cochrane Library were searched for relevant literature published between 2006 to March 2017. Online sources were searched for UK grey literature, and citation searching, and manual reference list screening were also carried out. Quantitative primary studies and systematic reviews, reporting actual or perceived effects on service delivery following the introduction of models of integration or co-ordination, in healthcare or health and social care settings in developed countries were eligible for inclusion. Strength of evidence for each outcome reported was analysed and synthesised using a four point comparative rating system of stronger, weaker, inconsistent or limited evidence. RESULTS: One hundred sixty seven studies were eligible for inclusion. Analysis indicated evidence of perceived improved quality of care, evidence of increased patient satisfaction, and evidence of improved access to care. Evidence was rated as either inconsistent or limited regarding all other outcomes reported, including system-wide impacts on primary care, secondary care, and health care costs. There were limited differences between outcomes reported by UK and international studies, and overall the literature had a limited consideration of effects on service users. CONCLUSIONS: Models of integrated care may enhance patient satisfaction, increase perceived quality of care, and enable access to services, although the evidence for other outcomes including service costs remains unclear. Indications of improved access may have important implications for services struggling to cope with increasing demand. TRIAL REGISTRATION: Prospero registration number: 42016037725

Development of Bi-polar plate design of PEM fuel cell using CFD techniques

This paper reviews the common existing designs of flow plates of fuel cells and suggests modifications to some of them to help reduce the pressure drop in the flow channels. Pressure drop is one of the factors that influence the overall performance of the cell both directly and indirectly through interaction with other factors including water management in the cell.The work uses computational fluid dynamics (CFD) to examine different design and study the effect of varying the flow rate (i.e. velocity) on the pressure drop for each of the designs modelled. Again, the designs are optimized by changing different parameters using ANSYS CFX. Results showing the effects of the modifications on pressure drop in the various plates are presented in this paper.From the study of the various designs, a conclusion was drawn that a modification of fuel cell designs in existence using a system similar to the diesel injection system design approach reduced the pressure drop in the fuel cell as shown by the simulation results.This reduction in pressure drop will contribute to the improvement of performance but it must be stressed that other factors also contribute to the overall performance of the cell and reduction in pressure drop alone is not a guarantee of better performance of a certain fuel cell design

Modelling and simulation of Proton Exchange Membrane fuel cell with serpentine bipolar plate using MATLAB

This report presents experimental results derived from a Proton Exchange Membrane fuel cell with a serpentine flow plate design. The investigation seeks to explore the effects of some parameters like cell operational temperature, humidification and atmospheric pressure on the general performance and efficiency of PEM fuel cell using MATLAB. A number of codes were written to generate the polarization curve for a single stack and five (5) cell stack fuel cell at various operating conditions. Detailed information of hydrogen and oxygen consumption and the effect they have on the fuel cell performance were critically analysed. The investigation concluded that the open circuit voltage generated was less than the theoretical voltage predicted in the literature. It was also noticed that an increase in current or current density reduced the voltage derived from the fuel cell stack. The experiment also clearly confirmed that when more current is being drawn from the fuel cell, more water will also be generated at the cathode section of the cell hence the need for an effective water management to improve the performance of the fuel cell. Other parameters like the stack efficiency and power density were also analysed using the experimental results obtained