Theoretical and Experimental Studies of Schottky Diodes That Use Aligned Arrays of Single Walled Carbon Nanotubes

We present theoretical and experimental studies of Schottky diodes that use aligned arrays of single walled carbon nanotubes. A simple physical model, taking into account the basic physics of current rectification, can adequately describe the single-tube and array devices. We show that for as grown array diodes, the rectification ratio, defined by the maximum-to-minimum-current-ratio, is low due to the presence of m-SWNT shunts. These tubes can be eliminated in a single voltage sweep resulting in a high rectification array device. Further analysis also shows that the channel resistance, and not the intrinsic nanotube diode properties, limits the rectification in devices with channel length up to ten micrometer.Comment: Nano Research, 2010, accepte

Predictors of Antibiotics Co-prescription with Antimalarials for Patients Presenting with Fever in Rural Tanzania.

Successful implementation of malaria treatment policy depends on the prescription practices for patients with malaria. This paper describes prescription patterns and assesses factors associated with co-prescription of antibiotics and artemether-lumefantrine (AL) for patients presenting with fever in rural Tanzania. From June 2009 to September 2011, a cohort event monitoring program was conducted among all patients treated at 8 selected health facilities in Ifakara and Rufiji Health and Demographic Surveillance System (HDSS).It included all patients presenting with fever and prescribed with AL. Logistic regression was used to model the predictors on the outcome variable which is co-prescription of AL and antibiotics on a single clinical visit. A cohort of 11,648 was recruited and followed up with 92% presenting with fever. Presumptive treatment was used in 56% of patients treated with AL. On average 2.4 (1 -- 7) drugs was prescribed per encounter, indicating co-prescription of AL with other drugs. Children under five had higher odds of AL and antibiotics co-prescription (OR = 0.63, 95% CI: 0.46 -- 0.85) than those aged more than five years. Patients testing negative had higher odds (OR = 2.22, 95%CI: 1.65 -- 2.97) of AL and antibiotics co-prescription. Patients receiving treatment from dispensaries had higher odds (OR = 1.45, 95% CI: 0.84 -- 2.30) of AL and antibiotics co-prescription than those from served in health centres even though the deference was not statistically significant. Regardless the fact that Malaria is declining but due to lack of laboratories and mRDT in most health facilities in the rural areas, clinicians are still treating malaria presumptively. This leads them to prescribe more drugs to treat all possibilities

Measuring the impact of road rehabilitation on spatial market efficiency in maize markets in Mozambique

This article analyzes the impact of road rehabilitation on the spatial market efficiency of maize markets in Mozambique. We estimate a modified version of the Parity Bounds Model (PBM) that allows us to test the impact of road rehabilitation on spatial efficiency. This article seeks to contribute to the existing literature in three ways. First, a unique data set, where road rehabilitation episodes between market pairs are identified, is developed. Second, special care is devoted to estimation of transaction costs due to the sensitivity of the PBM model to the quality of transaction costs estimates. Finally, as opposed to most existing literature that focuses on relatively distant markets, the article focuses on spatially closed markets. We find that maize markets tend to be segmented due to high transport costs. Following road rehabilitation, inefficiency and average absolute price differentials tend to decrease, and market pairs have tended to shift toward autarky regimes. Overall, while the results point broadly toward a positive impact of road rehabilitation on spatial efficiency, they are not as strong or as robust as one would like. Large increases in fuel prices likely offset the positive impacts of road rehabilitation on transaction costs, contributing to the increase in the probability of being in an autarky regime. Copyright (c) 2008 International Association of Agricultural Economists.