247 research outputs found
Spin communication over 30 m long channels of chemical vapor deposited graphene on SiO
We demonstrate a high-yield fabrication of non-local spin valve devices with
room-temperature spin lifetimes of up to 3 ns and spin relaxation lengths as
long as 9 m in platinum-based chemical vapor deposition (Pt-CVD)
synthesized single-layer graphene on SiO/Si substrates. The spin-lifetime
systematically presents a marked minimum at the charge neutrality point, as
typically observed in pristine exfoliated graphene. However, by studying the
carrier density dependence beyond n ~ 5 x 10 cm, via
electrostatic gating, it is found that the spin lifetime reaches a maximum and
then starts decreasing, a behavior that is reminiscent of that predicted when
the spin-relaxation is driven by spin-orbit interaction. The spin lifetimes and
relaxation lengths compare well with state-of-the-art results using exfoliated
graphene on SiO/Si, being a factor two-to-three larger than the best values
reported at room temperature using the same substrate. As a result, the spin
signal can be readily measured across 30 m long graphene channels. These
observations indicate that Pt-CVD graphene is a promising material for
large-scale spin-based logic-in-memory applications
Influence of doped-charge transport layers on the photovoltaic performance of donor-acceptor blend p-i-n type organic solar cells
This report demonstrates external power conversion efficiencies of 2% under 100 mW/cm2 simulated AM1.5 illumination for organic thin-film photovoltaic cells using a phthalocyanine-fullerene (ZnPc/C60) bulk heterojunction as an active layer, embedded into a p-i-n type architecture with doped wide-gap charge transport layers. For an optically optimized device, we found internal quantum efficiency (IQE) of above 80% under short circuit conditions. Such optically thin cells with high internal quantum efficiency are an important step towards high efficiency tandem cells. The p-i-n architecture allows for the design of solar cells with high internal quantum efficiency where only the photoactive region absorbs visible light and recombination losses at contacts are avoided. The I-V characteristics, power conversion efficiencies, the dependence of short circuit current on incident white light intensity, incident photon to collected electron efficiency (IPCE) and absorption spectra of the active layer system are discussed. KEY WORDS: Doped-charge transport layers, Organic solar cells, Photovoltaic cells,Phthalocyanine-fullerene  Bull. Chem. Soc. Ethiop. 2004, 18(1), 101-109
Exploring the relationship between job quality and firm productivity in the manufacturing sector: Panel data evidence from Ethiopia
By leveraging firm-level panel data from 400 agro-processing and leather manufacturing firms in Ethiopia, this paper investigates links between firm productivity and monetary and non-monetary dimensions of job quality. The results point to a positive impact of higher salaries on firm productivity, but limited effects of non-monetary job quality indicators. Specifically, a 10% increase on each of the salaries of tenured medium- and high-skilled workers increase sales per worker by 1.79% and 1.46%, respectively, ceteris paribus. Similarly, increasing the starting salary of medium-skilled workers by 10% increases profit per worker, sales per worker and value-add per worker by 2.27%, 2.43% and 2.44%, respectively. Non-monetary job quality indicators had a weak impact on productivity, however, reducing the incentive of employers to invest in job quality improvements. Impact of productivity increases on monetary and non-monetary job quality indicators follow a similar pattern. An increase in profit per worker was found to increase the salaries of both tenured employees and new hires. For instance, a 10% increase in profit per worker increases tenured salaries of low-and medium-skilled workers by 0.2% and 0.3%, respectively, and starting salaries for low, medium and high-skilled workers by 0.21%, 0.28% and 0.27%, respectively. However, a statistically significant impact of profit per worker and value add per worker on non-monetary aspects of job quality was not
Gender gaps in wages and nonmonetary benefits: Evidence from Ethiopia’s manufacturing sector
Using two rounds of panel firm- and worker-level data, this paper studies the gender gap in monetary and non-monetary compensation as well as work-related wellbeing among full-time workers in the agro-processing and leather sectors in Ethiopia. After controlling for year-fixed effects, the research reveals that women earn 35% less income from primary jobs and 40% less total income than men do. Some 40% of this primary job income gap and 43.3% of the income gap from all sources can be attributed to differences in human capital. Controlling for other worker, firm and manager characteristics as well as sector fixed effects do not meaningfully change the estimated coefficients. Child penalty explains part of the earning difference: the gender gap in total income between workers who do not have children is 11.7% while it is 37.6% among workers who have children. This difference is primarily because women who have children are 18.3% less likely to earn income from moonlighting and overtime work than men who have children do. Meanwhile, there is no statistically significant
gender difference in moonlighting and overtime work among workers who do not have children. Gender earning differences are highest among medium skilled workers. Moreover, women are less likely to receive housing, discounted or complementary meals, or on-the-job training than men. Despite these discrepancies, women report to be happier and more satisfied, and are more likely to rate working conditions positively than men. This satisfaction and happiness may reduce their aspiration and quest for equal pay and non-monetary benefits. Narrowing human capital differences and providing aspiration building for women may help to reduce the gender earning gap
Tuberculous lesions not detected by routine abattoir inspection: the experience of the Hossana municipal abattoir, southern Ethiopia
Summary The efficacy of the meat inspection procedures implemented for the detection of tuberculous cattle was evaluated by testing for bovine tuberculosis in 751 animals. The study involved routine inspection at slaughter, collection of tissues for detailed examination in the laboratory, and bacteriological investigation to identify Mycobacterium bovis. Of the 751 carcasses examined, 34 (4.5%) were found to have tuberculous lesions. Routine abattoir inspection detected only 29.4% of the carcasses with visible lesions. Eighty-four percent of the tuberculous lesions were found in the lungs and thoracic lymph nodes, 11.5% in the lymph nodes of the head, and the remaining 4.5% in the mesenteric and other lymph nodes of the carcasses. In addition, M. bovis was isolated from a carcass that presented no gross tuberculosis lesions. The low sensitivity of routine abattoir inspection demonstrates that existing necropsy procedures should be improved
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Investigating the impact of poverty on colonization and infection with drug-resistant organisms in humans: a systematic review
Background
Poverty increases the risk of contracting infectious diseases and therefore exposure to antibiotics. Yet there is lacking evidence on the relationship between income and non-income dimensions of poverty and antimicrobial resistance. Investigating such relationship would strengthen antimicrobial stewardship interventions.
Methods
A systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed, Ovid, MEDLINE, EMBASE, Scopus, CINAHL, PsychINFO, EBSCO, HMIC, and Web of Science databases were searched in October 2016. Prospective and retrospective studies reporting on income or non-income dimensions of poverty and their influence on colonisation or infection with antimicrobial-resistant organisms were retrieved. Study quality was assessed with the Integrated quality criteria for review of multiple study designs (ICROMS) tool.
Results
Nineteen articles were reviewed. Crowding and homelessness were associated with antimicrobial resistance in community and hospital patients. In high-income countries, low income was associated with Streptococcus pneumoniae and Acinetobacter baumannii resistance and a seven-fold higher infection rate. In low-income countries the findings on this relation were contradictory. Lack of education was linked to resistant S. pneumoniae and Escherichia coli. Two papers explored the relation between water and sanitation and antimicrobial resistance in low-income settings.
Conclusions
Despite methodological limitations, the results suggest that addressing social determinants of poverty worldwide remains a crucial yet neglected step towards preventing antimicrobial resistance
Importance of Ethnicity, CYP2B6 and ABCB1 Genotype for Efavirenz Pharmacokinetics and Treatment Outcomes: A Parallel-group Prospective Cohort Study in two sub-Saharan Africa Populations.
We evaluated the importance of ethnicity and pharmacogenetic variations in determining efavirenz pharmacokinetics, auto-induction and immunological outcomes in two African populations. ART naïve HIV patients from Ethiopia (n = 285) and Tanzania (n = 209) were prospectively enrolled in parallel to start efavirenz based HAART. CD4+ cell counts were determined at baseline, 12, 24 and 48 weeks. Plasma and intracellular efavirenz and 8-hydroxyefvairenz concentrations were determined at week 4 and 16. Genotyping for common functional CYP2B6, CYP3A5, ABCB1, UGT2B7 and SLCO1B1 variant alleles were done. Patient country, CYP2B6*6 and ABCB1 c.4036A>G (rs3842A>G) genotype were significant predictors of plasma and intracellular efavirenz concentration. CYP2B6*6 and ABCB1 c.4036A>G (rs3842) genotype were significantly associated with higher plasma efavirenz concentration and their allele frequencies were significantly higher in Tanzanians than Ethiopians. Tanzanians displayed significantly higher efavirenz plasma concentration at week 4 (p<0.0002) and week 16 (p = 0.006) compared to Ethiopians. Efavirenz plasma concentrations remained significantly higher in Tanzanians even after controlling for the effect of CYP2B6*6 and ABCB1 c.4036A>G genotype. Within country analyses indicated a significant decrease in the mean plasma efavirenz concentration by week 16 compared to week 4 in Tanzanians (p = 0.006), whereas no significant differences in plasma concentration over time was observed in Ethiopians (p = 0.84). Intracellular efavirenz concentration and patient country were significant predictors of CD4 gain during HAART. We report substantial differences in efavirenz pharmacokinetics, extent of auto-induction and immunologic recovery between Ethiopian and Tanzanian HIV patients, partly but not solely, due to pharmacogenetic variations. The observed inter-ethnic variations in efavirenz plasma exposure may possibly result in varying clinical treatment outcome or adverse event profiles between populations
A systems and partnership approach to agricultural research for development: Lessons from Ethiopia
In spite of the availability of several improved agricultural technologies
generated by the research system in Ethiopia over the last four decades, adoption of
these innovations by smallholder farmers has been very low. This has led to
stagnation of agricultural productivity and low crop yields, exposing the country to
recurrent food shortfalls and national food insecurity. The old approach to
agricultural research emphasized developing new technologies mainly through onstation
research that were then supposed to reach farmers through the public-sector
extension system. The Ethiopian Institute of Agricultural Research (EIAR) has in
recent years introduced a shift in agricultural research for development, which is
based on the innovation systems approach that involved cultivating partnerships
with several actors along the value chain, especially farmers, farmers’ cooperatives
and input suppliers. This paper presents the methodology used to facilitate
agricultural innovations and the diffusion of new technologies and illustrates the
outcomes of this initiative with regard to technology adoption, productivity growth
and the market orientation of production. The authors use examples from
experiences in scaling up three grain legumes. Compared to the three-year baseline
average (2003–05), crop output increased nationally by 89%, 85% and 97% in
2008 for common bean, chickpea and lentil respectively. Nationally, 53–59% of the
output growth is attributable to yield growth due to technological change, while the
balance is due to area expansion. These results affirm that the new approach has led
to accelerated adoption of new and high-yielding or low-risk varieties
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