Holographic Recording Materials Development

Organic photorefractive materials were evaluated for application in a reversible holographic memory system. Representative indigo and thioindigo derivatives and several stilbene derivatives were studied as well as 15, 16-dialkyldihydropyrene derivatives the following goals were achieved: (1) the successful writing of phase holograms in a thioindigo/polymer gel system, (2) the successful writing and erasing of phase holograms in a variety of indigo/polymer gel and indigo/solid polymer systems, and (3) the identification of indigoid dyes and 15, 16-dialkyldihydropyrene derivatives as materials potentially suitable for utilization in an operational system. Photochemical studies of the stilbene, indigo, thioindigo, and dialkyldihydropyrene derivatives in solution and in a variety of polymer matrix materials were conducted with the goal of optimizing the photorefractive behavior of the chemical system as a whole. The spectroscopic properties required of optimal photorefractive materials were identified, and it was shown that both the indigoid dyes and the dialkyldihydropyrenes closely match the required properties

Excitonic Transitions and Off-resonant Optical Limiting in CdS Quantum Dots Stabilized in a Synthetic Glue Matrix

Stable films containing CdS quantum dots of mean size 3.4 nm embedded in a solid host matrix are prepared using a room temperature chemical route of synthesis. CdS/synthetic glue nanocomposites are characterized using high resolution transmission electron microscopy, infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. Significant blue shift from the bulk absorption edge is observed in optical absorption as well as photoacoustic spectra indicating strong quantum confinement. The exciton transitions are better resolved in photoacoustic spectroscopy compared to optical absorption spectroscopy. We assign the first four bands observed in photoacoustic spectroscopy to 1se–1sh, 1pe–1ph, 1de–1dhand 2pe–2phtransitions using a non interacting particle model. Nonlinear absorption studies are done using z-scan technique with nanosecond pulses in the off resonant regime. The origin of optical limiting is predominantly two photon absorption mechanism

Understanding informal payments in health care: motivation of health workers in Tanzania

<p>Abstract</p> <p>Background</p> <p>There is growing evidence that informal payments for health care are fairly common in many low- and middle-income countries. Informal payments are reported to have a negative consequence on equity and quality of care; it has been suggested, however, that they may contribute to health worker motivation and retention. Given the significance of motivation and retention issues in human resources for health, a better understanding of the relationships between the two phenomena is needed. This study attempts to assess whether and in what ways informal payments occur in Kibaha, Tanzania. Moreover, it aims to assess how informal earnings might help boost health worker motivation and retention.</p> <p>Methods</p> <p>Nine focus groups were conducted in three health facilities of different levels in the health system. In total, 64 health workers participated in the focus group discussions (81% female, 19% male) and where possible, focus groups were divided by cadre. All data were processed and analysed by means of the NVivo software package.</p> <p>Results</p> <p>The use of informal payments in the study area was confirmed by this study. Furthermore, a negative relationship between informal payments and job satisfaction and better motivation is suggested. Participants mentioned that they felt enslaved by patients as a result of being bribed and this resulted in loss of self-esteem. Furthermore, fear of detection was a main demotivating factor. These factors seem to counterbalance the positive effect of financial incentives. Moreover, informal payments were not found to be related to retention of health workers in the public health system. Other factors such as job security seemed to be more relevant for retention.</p> <p>Conclusion</p> <p>This study suggests that the practice of informal payments contributes to the general demotivation of health workers and negatively affects access to health care services and quality of the health system. Policy action is needed that not only provides better financial incentives for individuals but also tackles an environment in which corruption is endemic.</p

Associations of psychosocial stress with type 2 diabetes and glycaemic control among Ghanaians: The RODAM study

Background: The extent to which psychosocial stress relates to type 2 diabetes among sub-Saharan Africans is not well understood. We assessed associations of psychosocial stresses with type 2 diabetes status and glycaemic control among Ghanaians. Methods: We used data from Research on Obesity and Diabetes among African Migrants (RODAM) study. We performed logistic and linear regression models to assess association of psychosocial stresses with type 2 diabetes and HbA1c respectively with adjustments for age, sex, education and other stresses. We also assessed moderation effects of migration status (migrant Ghanaians vs. non-migrant Ghanaians), age, sex and education by adding interaction terms in models. Results: Four thousand eight hundred and forty one Ghanaians were included with 44% resident in Ghana, 62% women, mean age of 46 years and 10% having type 2 diabetes. Psychosocial stress at home and at work were not associated with type 2 diabetes or HbA1c levels. Negative life events in past 12 months were negatively associated with type 2 diabetes (adjusted odds ratio = 0.93, 95% CI 0.87–0.99). Perceived discrimination was positively associated with type 2 diabetes (aOR = 1.01, 95% CI 1.004–1.03). Both associations were more pronounced in men. Perceived discrimination was also positively associated with HbA1c levels, especially among those with type 2 diabetes (adjusted β = 0.01, 95% CI 0.007–0.02). Conclusions: Perceived discrimination and negative life events are associated with type 2 diabetes and glycaemic control among Ghanaians, especially in men. Further studies are needed to identify context-specific mechanisms underlying these associations