Trends in life expectancy and the macroeconomy in Malawi

The purpose of this paper was to study trends in life expectancy in Malawi since independence and offer possible explanations regarding its inter-temporal variations. Descriptive analysis has shown that life expectancy in Malawi has trailed below Sub Saharan Africa’s average. From the 1960s through early 1980s, life expectancy improved due to rising incomes and absence of HIV/AIDS. After early 1980s life expectancy declined tremendously and never improved due to the spread of HIV/AIDS, the economic slump that followed the World Bank’s Structural Adjustment programmes (SAP) and the widespread corruption and poor governance in the era of democracy. It is found that at the turn of the new millennium, Malawians were no healthier than their ancestors at the dawn of independence, though such a trend somehow started changing for the better after 2004. In order to meet her health Millennium Development Goals by 2015, Malawi needs to put good governance, agricultural performance and increases in health expenditure at the heart of development policies.life expectancy; GDP; HIV/AIDS; Malawi

Does size of operated area matter? Evidence from Malawi's agricultural production

The objective of this paper was to examine the relationship between farm size and agricultural productivity using data from Malawi. This paper has examined the relationship using ordinary least squares regression with heteroskedasticity consistent covariance matrix (HC3) standard errors having confirmed absence of endogeneity of farm size. The major finding is that, contrary to the findings of earlier studies which reported a positive relationship, there is strong evidence that probably the post market liberalization period (1990s) became characterized by an inverse farm size productivity relationship. This finding suggests that well-thought-after land and credit market interventions or land redistribution from the rich to the land poor households would possibly raise total output thorough productivity gains.Farm size; Productivity; Inverse Relationship; Malawi

F. necrophorum Ecotin Inhibits Human Plasma Kallikrein and Human Neutrophil Elastase

Background: Fusobacterium necrophorum is a causative agent of Lemierre’s syndrome (LS) which is characterised by thrombophlebitis of the jugular vein and bacteraemia. F. necrophorum is a Gram-negative, anaerobic bacterium known to possess virulence genes such as a haemolysin, filamentous haemagglutinin and leukotoxin, which target host blood components. Ecotin is a serine protease inhibitor that has not previously been characterised in F. necrophorum, but in E.coli has been shown to have a potent anticoagulant effect. Methods: Next generation and Sanger sequencing were used to confirm the presence of the ecotin gene in the genomes of a collection of F. necrophorum clinical and reference strains. When translated, it was found to be a highly conserved protein made up of 159 amino acids. A plasmid insert was synthesised and ligated into a pET-16b vector. BL21(DE3) chemically competent E. coli cells were used to express the histidine-tagged protein under IPTG conditions and the protein was purified using IMAC sepharose affinity chromatography. Ecotin was added to human plasma kallikrein at concentrations of 0, 12.5, 25, 50 and 100 nM and incubated for 1 hour at room temperature to equilibrate. Kallikrein substrate was then added at concentrations of 0.015, 0.03, 0.06, 0.125, 0.25 and 0.5 mM and fluorescence was monitored every minute for 30 minutes. Ecotin was also added to human neutrophil elastase (HNE) as above and absorbance was monitored every minute for 30 minutes after addition of HNE substrate at concentrations of 0.015 – 0.5 mM. Results: Results show that F. necrophorum ecotin inhibits human plasma kallikrein and human neutrophil elastase in a dose-dependent manner. Data will also be presented on the anticoagulant effects of ecotin during activated partial thromboplastin time, thrombin time and prothrombin time tests on human donor blood. Conclusion: F. necrophorum is known to enter the bloodstream and cause a life threatening condition, therefore understanding the virulence mechanisms that it utilises is of great importance. Inhibition of clotting cascade enzymes suggests that ecotin may play a role in regulating coagulation, while the inhibition of neutrophil elastase suggests another role is to protect the organism from host proteases

Comparison of virulence genes found in draft genomes of F. necrophorum

Fusobacterium necrophorum is a causative agent of persistent sore throat syndrome, tonsillar abscesses and Lemierre’s syndrome (LS) in humans. LS is characterised by thrombophlebitis of the jugular vein and bacteraemia. It is a Gram-negative, anaerobic bacterium which to date has no available reference genome. Draft genomes suggest it to be a single circular chromosome of approximately 2.2Mb. A reference strain of each of the two F. necrophorum subspecies and a clinical isolate from a LS patient were sequenced on a Roche 454 GS-FLX+. Sequence data was assembled using Roche GS Assembler and the resulting contigs annotated using xBASE, Pfam and BLAST. The annotation data was mined for gene products associated with virulence revealing a leukotoxin, haemolysin, filamentous haemagglutinnin, adhesin, hemin receptor, phage genes, CRISPR-associated proteins, ecotin and a putative type V secretion system. Data will be presented on comparative genomics of the three strains, with a focus on putative virulence genes. Tools such as Artemis Comparison Tool and ClustalO were used for sequence alignments and PhyML was used to generate phylogenetic trees. Conserved motifs associated with virulence were also located. Understanding variations at the genomic level may help to explain the increased virulence of some F. necrophorum strains

Bioinformatics: a useful tool for the molecular microbiologist?

Following hard on the heels of the human genome project, microbial genome versions have now begun to produce vast amounts of information on the nucleotide sequences of specific microbes. How useful is this information and how can researchers wade through the millions of base pairs of sequence data to find genes or sequences of interest for either diagnostic or therapeutic strategies? In theory, the answer lies with the new specialty of bioinformatics, which covers genomics, proteomics and metabolomics - terms that are more recognisable to many as molecular genetics and biochemistry

Real-Time Power Management of A Fuel Cell/Ultracapacitor Hybrid

This thesis presents the system architecture design, system integration methodology, and real-time control of a fuel cell/ultracapacitor hybrid power system. The main objective is for the hybrid system to respond to real-world fluctuations in power without negatively impacting fuel cell life. A Proton Exchange Membrane (PEM) Fuel Cell is an electrochemical device which converts the chemical energy of pure hydrogen into electricity through a chemical reaction with oxygen. The high conversion efficiency, zero harmful emissions, high power-to-weight ratio, scalability, and low temperature operation make PEM fuel cells very attractive for stationary and portable power applications. However, fuel cells are limited in responding to fast transients in power demand, moreover power fluctuations have negative impact on fuel cell durability. This motivates the use of a supplementary energy storage device to assist the fuel cell by buffering sharp transients in power demand. The high power density, long cycle life, and efficiency of ultracapacitors make them an ideal solution for such auxiliary energy storage in a hybrid fuel cell system. The power management strategy that determines the power split between the fuel cell and ultracapacitor is key to the power following capability, long-term performance, and life-time of the fuel cell. In this thesis, a rule-based and a model predictive control strategy are designed, implemented and evaluated for power management of a fuel cell/ultracapacitor hybrid. The high-level control objectives are to respond to rapid variations in load while minimizing damaging fluctuations in fuel cell current and maintaining ultracapacitor charge (or voltage) within allowable bounds. An experimental test stand was created to evaluate the performance of the controllers. The test stand connects the fuel cell and ultracapacitor to an electronic load through two dc/dc converters, which provide two degrees of freedom, enabling independent low-level control of the DC BUS voltage and the current split between the fuel cell and ultracapacitor. Experiments show that both rule-based and model predictive power management strategies can be tuned to meet both high and low-level control objectives for a given power demand profile. However, the capability to explicitly enforce the constraints in model predictive scheme and its predictive nature in meeting power demands enables a more systematic design and results in general in smoother performance