Strong plasmonic fluorescence enhancement of individual plant light-harvesting complexes

Plasmonic coupling of metallic nanoparticles and adjacent pigments can dramatically increase the brightness of the pigments due to the enhanced local electric field. Here, we demonstrate that the fluorescence brightness of a single plant light-harvesting complex (LHCII) can be significantly enhanced when coupled to single gold nanorods (AuNRs). The AuNRs utilized in this study were prepared via chemical reactions, and the hybrid system was constructed using a simple and economical spin-assisted layer-by-layer technique. Enhancement of fluorescence brightness of up to 240-fold was observed, accompanied by a 109-fold decrease in the average (amplitude-weighted) fluorescence lifetime from approximately 3.5 ns down to 32 ps, corresponding to an excitation enhancement of 63-fold and emission enhancement of up to 3.8-fold. This large enhancement is due to the strong spectral overlap of the longitudinal localized surface plasmon resonance of the utilized AuNRs and the absorption or emission bands of LHCII. This study provides an inexpensive strategy to explore the fluorescence dynamics of weakly emitting photosynthetic light-harvesting complexes at the single molecule level.Comment: 23 pages, 6 figures, 2 supplementary figures, and supplementary equation

Optimizing Control of a Power System during an Emergency

Population growth, infrastructure and economy puts pressure and demand on the existing power supplies. It puts strains on the current power systems which causes instabilities in the systems. This is an ongoing challenge which needs an immediate solution. The objective of this thesis is voltage stability. This is examined with the help of constructing a small power system using a programming language called Matlab. Optimization tools provided by Matlab are used to find the maximum possible pre-contingency load, while still maintaining a stable system. To find feasible solutions in Matlab, system models, such as load models and power line models are simplified. The results show that a system which has experienced a fault can successfully recover by using a linear load recovery model and an exponential load recovery model. Certain constraints, such as generator ramping and limitations on the field voltages in the generators are implemented. Feasible olutions are found although constraints might have made it more difficult under the course of this study. These findings are rough approximations of how a small power system can operate. Though, this can give valuable information on how a more complex system might act before and after a contingency as well as suitable recovery paths. Although the thesis is more suited for those who have some knowledge in control or power systems, a reader without a technical background can enjoy the paper too

The Relative information content of complementary and supplementary narrative commentary in UK interim reports.

The main objective of the research is to investigate the relative information content of complementary and supplementary narrative commentaries in UK interim reports. The study also examines the relative importance of complementary and supplementary narrative attributes. The subsidiary objective of the study is to investigate incremental information content of complementary and supplementary narratives. The study used 309 interim reports of 103 companies for the years 2005 to 2007. The returns used were daily market adjusted cumulative abnormal returns ±5 days around the announcement of interim reports. The disclosure index method was used to capture complementary and supplementary information using disclosure variety (number of information items) and disclosure depth set of attributes (good news, amounts and comparison of current with past performance, reasons for performance and forward-looking). The control variables included financial performance measures of dividend yield, earnings per share and total assets. Event studies based multiple regression models were used to measure information content. The findings in respect of the main objective indicate that supplementary narratives had higher but insignificant infonnation content than complementary narratives for the model based on disclosure variety. However, when disclosure depth is used, complementary narratives have higher and significant relative information content than supplementary narratives. The results also show that complementary good news, complementary amounts and comparisons of current with past performance and complementary reasons for performance were associated with returns unlike their respective counterparts in supplementary narratives. Both complementary and supplementary forward-looking attributes were not associated with returns. The results of the subsidiary objective suggest that the disclosure varit)ty model combining complementary and supplementary narratives when compared with the disclosure variety model having supplementary narratives does not have a significant difference. All other incremental information content comparisons based on either disclosure variety or disclosure depth had significant differences. This study has a number of research and policy implications, especially after the 2007 subprime financial crisis

Prevalence and correlates of cytopenias in HIV-infected adults initiating highly active antiretroviral therapy in Uganda

Background: Cytopenias are the most common HIV-associated hematological abnormality. Cytopenias have been associated with several factors including sex, race/ethnicity, geographical location and comorbidities such as tuberculosis, hepatitis B infection, fever and oral candidiasis. Cytopenias become more prevalent as HIV progresses and are often fatal. Data from resource-limited settings about the prevalence and correlates of cytopenia are limited. Therefore we conducted this cross-sectional study to assess the prevalence and correlates of cytopenia among adult AIDS patients at initiation of HAART in Uganda. Methods: 400 HIV-infected subjects who were HAART-naive or on HAART for <= 6 months were enrolled into the Multivitamins, HAART and HIV/AIDS Trial. Anemia was defined according to WHO guidelines as any hemoglobin concentration < 12 g/dl for non-pregnant females and < 13 g/dl for males. Leucopenia and thrombocytopenia were defined using study site laboratory reference ranges for lack of generally accepted definitions for these 2 cell lines as leucopenia if white blood cell count < 2.75 x 10(9) cells/litre and thrombocytopenia if platelets < 125 x 10(9) cells/litre for females and &lt; 156 x 10(9) cells/litre for males. Univariate and bivariate analyses were done to describe the patient population and log-binomial regression was used to quantify the correlates of cytopenia. Results: Sixty five percent of the 400 subjects had at least one form of cytopenia. Anemia occurred in 47.8%, leucopenia in 24.3%, thrombocytopenia in 8.3%, bicytopenia in 21.9% and only 2 had a pancytopenia. Cytopenia was more prevalent in females (prevalence ratio [PR]: 1.33, 95% confidence interval [CI]: 1.12-1.59); CD4 count category 50 to < 200 (PR: 0.75, 95% CI: 0.64-0.88) and CD4 count category 200 to < 350 (PR: 0.74, 95% CI: 0.59-0.92) compared to CD4 count category < 50; normal BMI (PR: 0.82, 95% CI: 0.68-1.00) and overweight BMI (PR: 0.64, 95% CI: 0.50-0.82) compared to underweight BMI and those with a history or presence of oral candidiasis. Conclusions: Cytopenias are a frequent complication in HIV-infected adults at initiation of HAART in Uganda. The presence of any cytopenia was associated with female sex, decreasing CD4 count and decreasing body mass index. Prospective studies in resource-limited settings on the trend in HIV-related cytopenias are needed

A Cross-sectional Survey of the Determinants of Maternal Health Services Utilization among Women with Disability in Mbale District, Uganda.

Background: The study aimed to evaluate the determinants of maternal health services utilization among women with disability (WWD) in the Mbale district in Uganda. Methodology: The study approach was a mixed qualitative and quantitative cross-sectional design. The selection of study participants was by snowballing for the quantitative tool and purposively sampling for the Key Informants. A sample size of 189 women with disabilities was used in the study and 8 key informants were interviewed. Data analysis was carried out using the Statistical Package for Social Sciences (SPSS) version 22, and qualitative data were subjected to thematic analysis. Findings: The proportion of WWD utilizing MHS was found to be low in the Mbale district with only 17.7% attending four or more antenatal visits. Fear of stigma was the main barrier to the utilization of maternal health services. Health education influenced the utilization of maternal health services. Utilization of maternal health services (MHS) among women with disabilities was associated with socio-economic determinants (secondary level education, spousal support, and monthly income). Finally, there was a significant association between accessibility and the utilization of MHS. Conclusion:   This study revealed that external factors form the main barriers to the utilization of maternal health services among women with disability.   Recommendations:   Training and equipping health facility staff to be more sensitive to and attend to the unique needs of WWD could improve the experiences of WWD seeking MHS at the health facility. This may reduce their fear of stigmatization thus improving service utilization.

Structural Modeling of Food Safety Knowledge, Attitude, and Practices of Food Handlers in Highway Tourist Stop-Over Food Service Establishments in Uganda

The study examines the socio-demographic characteristics, food safety knowledge, attitudes, and practices of food handlers in highway tourist stop-over food service establishments in Uganda. The study further explores the relationship between the above factors using the Structural Equation Model (SEM). Understanding food safety knowledge, attitudes, and practices of food handlers can inform future interventions toward food safety assurance in food service establishments. The study used a cross-sectional design and data was collected using a self-administered structured questionnaire. Data was analyzed using Statistical Package for Social Sciences (SPSS) Version 22 and Analysis of Moment Structures (AMOS). Approximately half of the respondents had adequate knowledge of food safety and good practices. The results from SEM confirmed that food safety knowledge significantly affected practices (β= 0.37 p&lt;0.05), attitude insignificantly, and negatively affected practices (β= -0.04 p&gt;0.05). Only 13.3% of the changes in practices were explained by the knowledge and attitudes of the respondents (R-squared 0.133). The majority of the food handlers were males, had experience of more than 2 years, attended food safety training, and had limited knowledge about Hazard Analysis Critical Control Points (HACCP). The study is the first of its kind in Uganda. The findings suggest that future interventions should look beyond food safety knowledge and attitudes of the food handlers in food safety assurance efforts