Feature extraction of arc tracking phenomenon

This document outlines arc tracking signals -- both the data acquisition and signal processing. The objective is to obtain the salient features of the arc tracking phenomenon. As part of the signal processing, the power spectral density is obtained and used in a MATLAB program

A study of charged particles/radiation damage to VLSI device materials

Future spacecraft systems such as the manned space station will be subjected to low-dose long term radiation particles. Most electronic systems are affected by such particles. There is therefore a great need to understand device physics and failure mechanisms affected by radiation and to design circuits that would be less susceptible to radiation. Using 2 MeV electron radiation and bias temperature aging, it was found that MOS capacitors that were prepositively biased have lower flatband voltage shift and lesser increase in density of surface state charge than those that were not prepositively biased. In addition, it was shown that there is continued recovery of flatband voltage and density of state charge in irradiated capacitors during both room temperature anneal and 137 degree anneal. When nMOS transistors were subjected to 1 MeV proton radiation, charge pumping and current versus voltage measurements indicated that transconductance degradation, threshold voltage shifts and changes in interface states density may be the primary cause of nMOS transistor failure after radiation. Simulation studies using SPICE were performed on CMOS SRAM cells of various transistor sizes. It is shown that transistor sizing affects the noise margins of CMOS SRAM cells, and that as the beta ratio of the transistors of the CMOS SRAM cell decreases, the effective noise margin of the SRAM cell increases. Some suggestions were made in connection with the design of CMOS SRAMS that are hardened against single event upsets

Fault handling schemes in electronic systems with specific application to radiation tolerance and VLSI design

Naturally occurring space radiation particles can produce transient and permanent changes in the electrical properties of electronic devices and systems. In this work, the transient radiation effects on DRAM and CMOS SRAM were considered. In addition, the effect of total ionizing dose radiation of the switching times of CMOS logic gates were investigated. Effects of transient radiation on the column and cell of MOS dynamic memory cell was simulated using SPICE. It was found that the critical charge of the bitline was higher than that of the cell. In addition, the critical charge of the combined cell-bitline was found to be dependent on the gate voltage of the access transistor. In addition, the effect of total ionizing dose radiation on the switching times of CMOS logic gate was obtained. The results of this work indicate that, the rise time of CMOS logic gates increases, while the fall time decreases with an increase in total ionizing dose radiation. Also, by increasing the size of the P-channel transistor with respect to that of the N-channel transistor, the propagation delay of CMOS logic gate can be made to decrease with, or be independent of an increase in total ionizing dose radiation. Furthermore, a method was developed for replacing polysilicon feedback resistance of SRAMs with a switched capacitor network. A switched capacitor SRAM was implemented using MOS Technology. The critical change of the switched capacitor SRAM has a very large critical charge. The results of this work indicate that switched capacitor SRAM is a viable alternative to SRAM with polysilicon feedback resistance

Rebuilding after emergency: Revamping agricultural research in Sierra Leone after civil war

"The civil war in Sierra Leone, caused by a mix of political, social, and economic factors, had a huge impact on the overall economy in general and on the performance of the agricultural sector in particular. The agricultural research system of Sierra Leone was severely affected by the civil war. Research infrastructure was destroyed, laboratories were damaged and abandoned, and well-trained researchers and scientists fled from the country. With the cessation of hostilities in 2002, the government of Sierra Leone concentrated its efforts on the resettlement of displaced persons and on social and economic reconstruction. The efforts of the government include the rehabilitation and reorganization of the former National Agricultural Research Coordinating Council (NARCC), which was coordinating agricultural research in Sierra Leone. The Sierra Leone Agricultural Research Institute (SLARI) Act was passed by the parliament of Sierra Leone in 2007 to replace NARCC. As a new organization, SLARI needed to make strategic decisions to guide its operations in order to make it effective in responding to the demands of stakeholders within the food and agriculture system. To provide a focus for SLARI and link its agenda to national development priorities, a strategic plan and operational plan were developed. The methodology used to design the SLARI strategic plan applied an organizational innovation model through which the plan was nested within the strategic plan of the Forum for Agricultural Research in Africa (FARA) and Conseil Ouest et Center Africain pour la Recherche et le Développement Agricoles (CORAF) / West and Central African Council for Agricultural Research and Development (WECARD), and the operational plan was hinged on Comprehensive African Agricultural Development Program (CAADP) and Framework for African Agricultural Productivity (FAAP) principles. This would ensure synergy with regional and subregional strategies. The strategic plan would promote increased coordination, interaction, interlinkages, partnerships, and networks among the various agents associated with agricultural research for development systems in Sierra Leone. It would also help achieve SLARI's vision of increasing food security and wealth among Sierra Leone's rural population. For SLARI to make a meaningful contribution to agricultural development in Sierra Leone, the operational plan must be implemented in such a way that the results envisaged in the strategic plan can be achieved. This requires funds and commitment from all stakeholders, especially the government of Sierra Leone." from authors' abstractwar, Agriculture, Development, Research, Strategic plan, Operational plan, Science and technology, Agricultural research,

Institutional and public expenditure review of Ghana’s Ministry of Food and Agriculture

The need for agricultural ministries to have the capacity to develop appropriate policies and effectively implement them is becoming increasingly important as African countries, following on their commitment to Comprehensive Africa Agriculture Development Program (CAADP), pursue economic growth through agriculture-led development. The ministries need to take the lead in pulling together evidence based strategies and building partnerships that ensures their ownership. As donors begin to align their policies with those of governments, an increasingly large share of external support to agriculture is likely to be delivered in the form of support to budgets rather than specially implemented projects. Capacities of ministries and effectiveness public systems will have significant bearing on effectiveness and impact of investments in agriculture. This public expenditure and institutional review of Ghana’s Ministry of Food and Agriculture offers insights on diagnosing limitations to and identifying strategies for improving the capacity of ministries to make effective use of human and financial resources. The review makes use a conceptual framework in which mission and functions, organizational capacity – a combination of structures, processes and resources –and organizational incentives interact to produce organizational performance. Indicative strategies are recommended that the ministry can use to generate discussions internally and developed a set a reforms that are owned. They key message is that to improve performance both capacity and incentives faced by organizations need to be addressed.agriculture, ministry, capacity, expenditure review, institutions,

How to decide? Different methods of calculating gene expression from short oligonucleotide array data will give different results

BACKGROUND: Short oligonucleotide arrays for transcript profiling have been available for several years. Generally, raw data from these arrays are analysed with the aid of the Microarray Analysis Suite or GeneChip Operating Software (MAS or GCOS) from Affymetrix. Recently, more methods to analyse the raw data have become available. Ideally all these methods should come up with more or less the same results. We set out to evaluate the different methods and include work on our own data set, in order to test which method gives the most reliable results. RESULTS: Calculating gene expression with 6 different algorithms (MAS5, dChip PMMM, dChip PM, RMA, GC-RMA and PDNN) using the same (Arabidopsis) data, results in different calculated gene expression levels. Consequently, depending on the method used, different genes will be identified as differentially regulated. Surprisingly, there was only 27 to 36% overlap between the different methods. Furthermore, 47.5% of the genes/probe sets showed good correlation between the mismatch and perfect match intensities. CONCLUSION: After comparing six algorithms, RMA gave the most reproducible results and showed the highest correlation coefficients with Real Time RT-PCR data on genes identified as differentially expressed by all methods. However, we were not able to verify, by Real Time RT-PCR, the microarray results for most genes that were solely calculated by RMA. Furthermore, we conclude that subtraction of the mismatch intensity from the perfect match intensity results most likely in a significant underestimation for at least 47.5% of the expression values. Not one algorithm produced significant expression values for genes present in quantities below 1 pmol. If the only purpose of the microarray experiment is to find new candidate genes, and too many genes are found, then mutual exclusion of the genes predicted by contrasting methods can be used to narrow down the list of new candidate genes by 64 to 73%

High food prices: The what, who, and how of proposed policy actions

"The complex causes of the current food and agriculture crisis require a comprehensive response. In view of the urgency of assisting people and countries in need, the first set of policy actions— an emergency package—consists of steps that can yield immediate impact: 1. expand emergency responses and humanitarian assistance to food-insecure people and people threatening government legitimacy, 2. eliminate agricultural export bans and export restrictions, 3. undertake fast-impact food production programs in key areas, and 4. change biofuel policies. A second set of actions—a resilience package—consists of the following steps: 5. calm markets with the use of market-oriented regulation of speculation, shared public grain stocks, strengthened food-import financing, and reliable food aid; 6. invest in social protection; 7. scale up investments for sustained agricultural growth; and 8. complete the Doha Round of World Trade Organization (WTO) negotiations. Investment in these actions calls for additional resources. Policymakers should consider mobilizing resources from four sources: the winners from the commodity boom among countries; the community of traditional and new donor countries; direct or indirect progressive taxation and reallocation of public expenditures in the affected countries themselves; and mobilization of private sector finance, including through improved outreach of banking to agriculture. Because of countries' diverse situations, the design of programs must be country driven and country owned. Accountability for sound implementation must also rest with countries. At the same time, a new international architecture for the governance of agriculture, food, and nutrition is needed to effectively implement the initiatives described, and especially their international public goods components. Global and national action is needed, through existing mechanisms, well-coordinated special initiatives, and possibly a special fund." from TextFood prices, Food supply, Food demand, Social protection, Agricultural research, Agricultural policy, Agricultural subsidies,

Bacterial etiology of sexually transmitted infections at a STI clinic in Ghana; use of multiplex real time PCR

Background: Most sexually transmitted infection (STI) management efforts focus on the syndromic approach to diagnose and treat patients. However, most women with STIs have been shown to be entirely asymptomatic, or if symptoms exist, are often missed when either clinical or conventional bacteriologic diagnostic tools are employed.Methods: We assessed the performance of a multiplex real time PCR assay to describe other potential pathogens that could be missed by conventional bacteriological techniques in 200 women attending a routine STI clinic in Kumasi, Ghana.Results: Although a total 78.00% of the women were asymptomatic, 77.1% of them tested positive for at least one bacterial STI pathogen. Mycoplasma genitalium was the most commonly detectable pathogen present in 67.5% of all women. Of those testing positive, 25.0% had single infections, while 38.0% and 19.5% had double and triple infections respectively. Altogether, 86.54% and 90.91% of the symptomatic and asymptomatic women respectively tested positive for at least one pathogen (p<0.05). There were no significant associations (p<0.05) between the clinical manifestations of the symptomatic women and the pathogens detected in their samples.Conclusions: Our study confirmed the importance of complementing the syndromic approach to STI management with pathogen detection and most importantly recognise that STIs in women are asymptomatic and regular empirical testing even for both symptomatic and asymptomatic patients is critical for complete clinical treatment.Funding: EOD (Ellis Owusu-Dabo Research working group, KCCR)Keywords: Etiology, Syndromic, Sexually Transmitted Infections, Multiplex real time PC

Los altos precios de los alimentos: El ‘qué', ‘quién' y ‘cómo' de las acciones de política propuestas

"La complejidad de las causas de la actual crisis alimentaria y agrícola requiere de una respuesta integral. En vista de que es urgente prestar asistencia a las poblaciones y los países necesitados, la primera serie de acciones de política —un paquete de emergencia— consiste en varios pasos para generar un impacto inmediato: 1. Incrementar las acciones de emergencia y la ayuda humanitaria para incluir a las poblaciones que experimentan inseguridad alimentaria y a las que amenazan la legitimidad gubernamental; 2. Eliminar la prohibición y las restricciones a las exportaciones agrícolas; 3. Emprender programas que permitan rápidamente expandir la oferta alimentaria en áreas clave; y, 4. Modificar las políticas de los biocombustibles. Una segunda serie de acciones de política —un paquete de resiliencia socioeconómica— consiste en los siguientes pasos: 5. Proveer tranquilidad en los mercados mediante una regulación de los movimientos especulativos a través de instrumentos de mercado, reservas públicas y compartidas de granos, un mayor financiamiento para la importación de alimentos, y una ayuda alimentaria confiable; 6. Invertir en protección social; 7. Incrementar paulatinamente las inversiones para un crecimiento agrícola sostenido; y, 8. Concluir las negociaciones de la Ronda de Doha de la Organización Mundial del Comercio (OMC). La inversión en estas acciones requiere de recursos adicionales. Las instancias decisorias deberán considerar la movilización de recursos provenientes de cuatro fuentes: los países que se han beneficiado del auge de los commodities agrícolas; la comunidad de países donantes, tanto tradicionales como nuevos; impuestos proporcionales, directos o indirectos, y la reasignación del gasto público en los propios países afectados; y la movilización de los recursos financieros del sector privado, lo que incluye una ampliación en la cobertura de los servicios financieros para la agricultura. Debido a las diversas situaciones que enfrentan, los mismos países deben dirigir y apropiarse del diseño de los programas. La rendición de cuentas en cuanto a una implementación acertada también deberá recaer en los países. Al mismo tiempo, se necesita una nueva estructura internacional de gobernabilidad para la agricultura, la alimentación y la nutrición, a fin de implementar de forma eficaz las iniciativas descritas, especialmente los componentes relativos a los bienes públicos internacionales. También es necesaria la acción, tanto en el ámbito mundial como nacional, a través de los mecanismos existentes, iniciativas especiales muy bien coordinadas y posiblemente un fondo especial." from TextFood prices, Food supply, Food demand, Social protection, Agricultural research, Agricultural policy, Agricultural subsidies,