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Efficiency Differences (efficiency + difference)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Effect of Alkyl Side-Chain Length on Photovoltaic Properties of Poly(3-alkylthiophene)/PCBM Bulk Heterojunctions

ADVANCED FUNCTIONAL MATERIALS, Issue 20 2009
Abay Gadisa
Abstract The morphological, bipolar charge-carrier transport, and photovoltaic characteristics of poly(3-alkylthiophene) (P3AT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blends are studied as a function of alkyl side-chain length m, where m equals the number of alkyl carbon atoms. The P3ATs studied are poly(3-butylthiophene) (P3BT, m,=,4), poly(3-pentylthiophene) (P3PT, m,=,5), and poly(3-hexylthiophene) (P3HT, m,=,6). Solar cells with these blends deliver similar order of photo-current yield (exceeding 10,mA cm,2) irrespective of side-chain length. Power conversion efficiencies of 3.2, 4.3, and 4.6% are within reach using solar cells with active layers of P3BT:PCBM (1:0.8), P3PT:PCBM (1:1), and P3HT:PCBM (1:1), respectively. A difference in fill factor values is found to be the main source of efficiency difference. Morphological studies reveal an increase in the degree of phase separation with increasing alkyl chain length. Moreover, while P3PT:PCBM and P3HT:PCBM films have similar hole mobility, measured by hole-only diodes, the hole mobility in P3BT:PCBM lowers by nearly a factor of four. Bipolar measurements made by field-effect transistor showed a decrease in the hole mobility and an increase in the electron mobility with increasing alkyl chain length. Balanced charge transport is only achieved in the P3HT:PCBM blend. This, together with better processing properties, explains the superior properties of P3HT as a solar cell material. P3PT is proved to be a potentially competitive material. The optoelectronic and charge transport properties observed in the different P3AT:PCBM bulk heterojunction (BHJ) blends provide useful information for understanding the physics of BHJ films and the working principles of the corresponding solar cells. [source]

Effects of ownership, subsidization and teaching activities on hospital costs in Switzerland

HEALTH ECONOMICS, Issue 3 2008
Mehdi Farsi
Abstract This paper explores the cost structure of Swiss hospitals, focusing on differences due to teaching activities and those related to ownership and subsidization types. A stochastic total cost frontier with a Cobb,Douglas functional form has been estimated for a panel of 148 general hospitals over the six-year period from 1998 to 2003. Inpatient cases adjusted by DRG cost weights and ambulatory revenues are considered as two separate outputs. The adopted econometric specification allows for unobserved heterogeneity across hospitals. The results suggest that teaching activities are an important cost-driving factor and hospitals that have a broader range of specialization are relatively more costly. The excess costs of university hospitals can be explained by more extensive teaching activities as well as the relative complexity of the offered medical treatments from a teaching point of view. However, even after controlling for such differences university hospitals have shown a relatively low cost-efficiency especially in the first two or three years of the sample period. The analysis does not provide any evidence of significant efficiency differences across ownership/subsidy categories. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Genetic and catalytic efficiency structure of an HCV protease quasispecies,

HEPATOLOGY, Issue 4 2007
Sandra Franco
The HCV nonstructural protein (NS)3/4A serine protease is not only involved in viral polyprotein processing but also efficiently blocks the retinoic-acid,inducible gen I and Toll-like receptor 3 signaling pathways and contributes to virus persistence by enabling HCV to escape the interferon antiviral response. Therefore, the NS3/4A protease has emerged as an ideal target for the control of the disease and the development of new anti-HCV agents. Here, we analyzed, at a high resolution (approximately 100 individual clones), the HCV NS3 protease gene quasispecies from three infected individuals. Nucleotide heterogeneity of 49%, 84%, and 91% were identified, respectively, which created a dense net that linked different parts of the viral population. Minority variants having mutations involved in the acquisition of resistance to current NS3/4A protease inhibitors (PIs) were also found. A vast diversity of different catalytic efficiencies could be distinguished. Importantly, 67% of the analyzed enzymes displayed a detectable protease activity. Moreover, 35% of the minority individual variants showed similar or better catalytic efficiency than the master (most abundant) enzyme. Nevertheless, and in contrast to minority variants, master enzymes always displayed a high catalytic efficiency when different viral polyprotein cleavage sites were tested. Finally, genetic and catalytic efficiency differences were observed when the 3 quasispecies were compared, suggesting that different selective forces were acting in different infected individuals. Conclusion: The rugged HCV protease quasispecies landscape should be able to react to environmental changes that may threaten its survival. (HEPATOLOGY 2007;45:899,910.) [source]

Fund allocation within Australian dental care: an innovative approach to output based funding

AUSTRALIAN DENTAL JOURNAL, Issue 4 2005
M. Tennant
Abstract Background: Over the last 15 years in Australia the process of funding government health care has changed significantly. The development of dental funding models that transparently meet both the service delivery needs for data at the treatment level and policy makers' need for health condition data is critical to the continued integration of dentistry into the wider health system. Methods: This paper presents a model of fund allocation that provides a communication construct that addresses the needs of both policy makers and service providers. Results: In this model, dental treatments (dental item numbers) have been grouped into eight broad dental health conditions. Within each dental health condition, a weighted average price is determined using the Department of Veterans Affairs' (DVA) fee schedule as the benchmark, adjusted for the mix of care. The model also adjusts for the efficiency differences between sectors providing government funded dental care. In summary, the price to be applied to a dental health condition category is determined by the weighted average DVA price adjusted by the sector efficiency. Conclusions: This model allows governments and dental service providers to develop funding agreements that both quantify and justify the treatment to be provided. Such a process facilitates the continued integration of dental care into the wider health system. [source]