Optical and Raman characterization of ALD alumina coated multiwall carbon nanotubes and nanoporous gold film

Due to their large surface to volume ratio nanostructures are inherently unstable. To insure long term stability of nano-devices, they have to be rendered inert to their environment. In this study, nanoporous gold films(NPGF) and multiwall carbon nanotubes were coated with ALD alumina of varying thicknesses. Subsequently, the plasmonic property of the former and electronic property of the latter was monitored by Transmittance and Raman Spectroscopy respectively. Transmittance spectra revealed that NPGF passivated by ALD-alumina maintains its plasmonic properties, i.e. its LSPR supporting properties remained intact. Raman spectra of ALD alumina passivated MWNTs show no coating induced changes in its characteristic Raman features. This led to the conclusion that ALD alumina is a benign and suitable technique for thin film passivation of NPGF and MWNTs. This result supports the expansion of ALD’s domain as a reliable thin film passivation technique in areas of SERS based biosensor research and the passivation of carbon nanotubes

Group delay in Bragg grating with linear chirp

An analytic solution for Bragg grating with linear chirp in the form of confluent hypergeometric functions is analyzed in the asymptotic limit of long grating. Simple formulas for reflection coefficient and group delay are derived. The simplification makes it possible to analyze irregularities of the curves and suggest the ways of their suppression. It is shown that the increase in chirp at fixed other parameters decreases the oscillations in the group delay, but gains the oscillations in the reflection spectrum. The conclusions are in agreement with numerical calculations.Comment: 16 pages, 8 figures, submitted to Opt. Com

QUALITY RELATED PROBLEMS IN LARGE ETHIOPIAN MANUFACTURING FIRMS: IMPLICATIONS FOR COMPETENCY

<p>ENGLISH ABSTRACT: This study was conducted in sixteen manufacturing industries in Ethiopia. A structured questionnaire with 52 items (open questions, interviews, and facility observation) was used to collect data. The finding indicates that 55 (about 37%) of the large manufacturing firms are making significant losses. The main challenges to the industries are poor quality management, poor raw material quality, rising raw material prices, outdated technology, quality costs, inefficient systems, limitations of skills training, and low motivation. Excluding the systems, these factors correlated at about 79% with market competency. The study also found the widespread use of inspection as a means of problem detection in the manufacturing industries.</p><p>AFRIKAANSE OPSOMMING: Sestien groot vervaardigers in Ethiopië is ondersoek. ’n Gestruktureerde vraelys (52 vrae, onderhoude en waarneming) is gebruik vir die versameling van data. Die dataontleding het getoon dat 55 vervaardigers (ongeveer 37%) in 'n verliessituasie was. Die hoofoorsake was swak bestuursgehalte, swak grondstowwe, stygende materiaalpryse, verouderde tegnologie, gehaltekoste, ondoeltreffende sisteme, opleidingstekorte, en ‘n gebrek aan motivering. Met die uitsondering van sisteemdoeltreffendheid, is daar ‘n 79% korrelasie tussen die hoofoorsake en markbevoegdheid. Die studie het ook gevind dat inspeksie algemeen as probleemopsporingstegniek gebruik word.</p&gt

Democracy and Development: causality analysis using fsQCA

Since the industrial revolution, development has been at the center of politics and politics at the center of development. Whether democratic type of government or autocratic perform better has been discussed among economists and political scientists alike for years. The emergence of autocratic governments in South East Asia as champions in bringing fast growth has fueled the debate even more. Many dictatorships have made the success of these countries as a tool to question the attributes of democracy and in return legitimize their grip. Even though, democracy has its own merit irrespective of whether it brings fast growth or not, it is still a worthy cause to learn about its effectiveness more. Development and poverty alleviation have been the allure to my choice in studying Economics and my motivation to pursue my thesis in a subject that has been always closer to my heart. There is no consensus among economists, policy makers and political scientists as to how democratic properties of a regime in a country can bring a fast economic growth. But before the how, what is even democracy begs an answer. In my thesis I have tried to dig in to these broad conversation of definition of democracy. I discussed the concept of democracy the channels of growth that it can affect and then forwarded the empirical findings and arguments in the literature. Moreover, I have used in my empirical analysis fuzzy set qualitative comparative analysis (fsQCA), a rather fresh method of understanding causality and finding various paths to arrive at an outcome rather than solitary way propagated by other conventional methods. I included as many countries as possible so that many consistent paths of arriving at the outcome of development can be identified. The findings of my thesis indicate that one country can have a combination of different conditions in distinction to others, and achieve development

Design of a flat-top fiber Bragg filter via quasi-random modulation of the refractive index

The statistics of the reflection spectrum of a short-correlated disordered fiber Bragg grating are studied. The averaged spectrum appears to be flat inside the bandgap and has significantly suppressed sidelobes compared to the uniform grating of the same bandwidth. This is due to the Anderson localization of the modes of a disordered grating. This observation prompts a new algorithm for designing passband reflection gratings. Using the stochastic invariant imbedding approach it is possible to obtain the probability distribution function for the random reflection coefficient inside the bandgap and obtain both the variance of the averaged reflectivity as well as the distribution of the time delay of the grating

Scattering of evanescent wave by two cylinders near a flat boundary

Two-dimensional problem of evanescent wave scattering by dielectric or metallic cylinders near the interface between two dielectric media is solved numerically by boundary integral equations method. A special Green function was proposed to avoid the infinite integration. A pattern with a circular and a prolate elliptic cylinders, respectively, is suggested to simulate the sample and the probe in near-field optical microscopy. The energy flux in the midplane of the probe-cylinder is calculated as a function of its position.Comment: 10 pages, 4 figure

Tenofovir disoproxil fumarate for prevention of HIV infection in women: a phase 2, double-blind, randomized, placebo-controlled trial.

ObjectivesThe objective of this trial was to investigate the safety and preliminary effectiveness of a daily dose of 300 mg of tenofovir disoproxil fumarate (TDF) versus placebo in preventing HIV infection in women.DesignThis was a phase 2, randomized, double-blind, placebo-controlled trial.SettingThe study was conducted between June 2004 and March 2006 in Tema, Ghana; Douala, Cameroon; and Ibadan, Nigeria.ParticipantsWe enrolled 936 HIV-negative women at high risk of HIV infection into this study.InterventionParticipants were randomized 1:1 to once daily use of 300 mg of TDF or placebo.Outcome measuresThe primary safety endpoints were grade 2 or higher serum creatinine elevations (>2.0 mg/dl) for renal function, grade 3 or 4 aspartate aminotransferase or alanine aminotransferase elevations (>170 U/l) for hepatic function, and grade 3 or 4 phosphorus abnormalities (<1.5 mg/dl). The effectiveness endpoint was infection with HIV-1 or HIV-2.ResultsStudy participants contributed 428 person-years of laboratory testing to the primary safety analysis. No significant differences emerged between treatment groups in clinical or laboratory safety outcomes. Study participants contributed 476 person-years of HIV testing to the primary effectiveness analysis, during which time eight seroconversions occurred. Two were diagnosed in participants randomized to TDF (0.86 per 100 person-years) and six in participants receiving placebo (2.48 per 100 person-years), yielding a rate ratio of 0.35 (95% confidence interval = 0.03-1.93), which did not achieve statistical significance. Owing to premature closures of the Cameroon and Nigeria study sites, the planned person-years of follow-up and study power could not be achieved.ConclusionDaily oral use of TDF in HIV-uninfected women was not associated with increased clinical or laboratory adverse events. Effectiveness could not be conclusively evaluated because of the small number of HIV infections observed during the study