Optimal barrier subdivision for Kramers' escape rate

We examine the effect of subdividing the potential barrier along the reaction coordinate on Kramers' escape rate for a model potential. Using the known supersymmetric potential approach, we show the existence of an optimal number of subdivisions that maximises the rate.Comment: 8 pages, 3 figures, To appear in Pramana - J. Phys, Indi

Effect of Landauer's blowtorch on the equilibration rate in a bistable potential

Kinetic aspect of Landauer's blowtorch effect is investigated for a model double-well potential with localized heating. Using the supersymmetric approach, we derive an approximate analytical expression for the equilibration rate as function of the strength, width and the position of the hot zone, and the barrier height. We find that the presence of the hot zone enhances the equilibration rate, which is found to be an increasing function of the strength and width of the hot zone. Our calculations also reveal an intriguing result, namely, that placing the hot zone away from the top of the potential barrier enhances the rate more than when it is placed close to it. A physically plausible explanation for this is attempted. The above analytical results are borne out by detailed numerical solution of the associated Smoluchowski equation for the inhomogeneous medium.Comment: 15 pages in LaTeX format and 6 figures in postscript E-Mail : [email protected] [email protected]

Preliminary Study on the Impact of Water Quality and Irrigation Practices on Soil Salinity and Crop Production, Gergera Watershed, Atsbi-Wonberta, Tigray, Northern Ethiopia

Possible long term effects on soil salinity and crop production due to the quality of water and irrigation practices is assessed in an area in Gergera Watershed in Atsbi-Wonberta, Tigray, northern Ethiopia. Ten water  samples collected from hand-dug wells and small household ponds, and thirty soil samples from different depths up to ~100cm were tested for  various parameters such as TDS, pH, anions and cations. Data indicate that both water and soil in terms of quality are acceptable for irrigation  purposes. However, at present the soil salinity is not a serious issue but the data suggests its possible increase with time as indicated by two samples. Some of the issues such as use of sprinklers, organic manure, blending, seasonal crops are discussed in the light of maintaining the  required quality, proper utilization of soil and water resources, and for sustainable development.Keywords: Watershed, Water quality, Soil quality, Hand-dug wells, House-hold Ponds

The Gap between Surgical Resident and Faculty Surgeons Concerning Operating Theatre Teaching: Report from Addis Ababa, Ethiopia

Background: In a continent like Africa where the number of surgeons is alarmingly few, training of a large number of residents is the way forward. However, sudden expansion in the number of trainees in an existing teaching environment may bring the quality of the most fundamentaleducation i.e. operation room teaching into question.Method: We wanted to investigate the different perceptions of our surgeons-under-training and faculty concerning preoperative preparation, intra operative teaching and postoperative feedback. A validated questionnaire was administered to our surgical residents and faculty at the Addis Ababa University, School of Medicine, Department of Surgery. Results were analyzed with 2-sample t tests, comparing Likert scores. Findings were significant if the p value was < 0.05.Results: Forty residents (15 second year, 15 third years and 10 final years) and 30 faculty members completed the survey. With respect to preoperative preparation, faculty were significantly more likely to claim that residents’ preparation in terms of reading is low (3.77 vs 2.45; p=0.001) and anatomy review (3.73 vs 2.34; p=0.001) before the procedure. There was a very significant difference with regards to intra-operative teaching activities, i.e teaching of the operative steps (2.60 vs 3.79; p=0.048), instrument handling (2.30 vs 3.72; p=0.002), and surgical technique (2.23vs 3.83; p= 0.001). Residents’ perception of the effort of the faculty to act as a teacher in the operating room was significantly lower compared to the faculty (2.13 vs 3.94; p=0.002). Postoperatively, significant differences were found in perceptions of positive feedback (2.48 vs 3.86; p=0.01) and feedback on areas to improve (1.85 vs 3.34; p=0.001).Conclusion: There is a universal agreement on the need to improve the current residency training. However, the difference between resident and faculty in the teaching-learning process is alarmingly significant. As there is no substitute for the intra-operative training of residents, every effort must be made to not to trade off number of graduates with quality and  competence of surgeons-under-training.  Keywords: Resident, Surgeons, Operating, Theatre, Teachin

Effects of nitrogen, phosphorus and vermicompost fertilizers on productivity of groundnut (Arachis hypogaea L.) in Babile, Eastern Ethiopia

ArticleThough groundnut (Arachis hypogaea L.) is a main cash crop for smallholder farmers in several districts of eastern Ethiopia, its yield is very low. Farmers apply little or no fertilizers to grow the crop possibly because no generic or recommended fertilizers rates available for farmers. Therefore field experiments were conducted for two consecutive cropping seasons in Babile district, to prove the hypothesis that one of the major factors that severely reduce the yield of the crop was lack of nutrients in the soil with the objective of investigating the effects of applying mineral NP fertilizers and vermicompost on the productivity of improved groundnut variety ‘BaHa-Gudo’. The experiment was 3 × 3 × 3 factorial with three replications laid down in a randomized complete block design comprising nitrogen (0, 23 and 46 kg N ha-1 ), phosphorus (0, 46 and 92 kg P2O5 ha-1 ) and vermicompost (0, 2.5 and 5 t vermicompost ha-1 ). The data on crop growth, nodulation and yield were collected and subjected to analysis of SAS 9.2 software. Means separation were made using Duncans Multiple Range Test (DMRT) at 5% level of significance. The results revealed that growth, yield attributes, and yields were significantly (P < 0.01) affected by the main and interactions effect of the treatments. The pod yield obtained from combined application of 46: 46 kg N: P2O5 ha-1 and 2.5 t vermicompost ha-1 exceeded the pod yield produced from nil application of fertilizers by about 100%. The economic analysis also indicated that the highest marginal rate of return (671%) and net benefit ($ 1,830) ha-1 were obtained from combined application of 46: 46 kg N: P2O5 ha-1 and 2.5 t vermicompost ha-1 . From the results it could be concluded that applying the aforementioned doses of fertilizers combination would enable farmers increase productivity of groundnut so as to enhance farmers’ income and livelihoods

Microscale Mechanics of Plug-and-Play In Vitro Cytoskeleton Networks

This chapter describes recent techniques that have been developed to reconstitute and characterize well-controlled, tunable networks of actin and microtubules outside of cells. It describes optical tweezers microrheology techniques to characterize the linear and nonlinear mechanics of these plug-and-play in vitro networks from the molecular-level to mesoscopic scales. It also details fluorescence microscopy and single-molecule tracking methods to determine macromolecular transport properties and stress propagation through cytoskeleton networks. Throughout the chapter the intriguing results that this body of work has revealed are highlighted—including how the macromolecular constituents of cytoskeleton networks map to their signature responses to stress or strain; and the elegant couplings between network structure, macromolecular mobility, and stress response that cytoskeleton networks exhibit

Increased activated memory B-cells in the peripheral blood of patients with erythema nodosum leprosum reactions.

B-cells, in addition to antibody secretion, have emerged increasingly as effector and immunoregulatory cells in several chronic inflammatory diseases. Although Erythema Nodosum Leprosum (ENL) is an inflammatory complication of leprosy, the role of B- cell subsets has never been studied in this patient group. Therefore, it would be interesting to examine the contribution of B-cells in the pathogenesis of ENL. A case-control study design was used to recruit 30 untreated patients with ENL and 30 non-reactional lepromatous leprosy (LL) patient controls at ALERT Hospital, Ethiopia. Peripheral blood samples were obtained before, during and after treatment from each patient. Peripheral blood mononuclear cells (PBMCs) were isolated and used for immunophenotyping of B- cell subsets by flow cytometry. The kinetics of B-cells in patients with ENL before, during and after Prednisolone treatment of ENL was compared with LL patient controls as well as within ENL group. Total B-cells, mature B-cells and resting memory B-cells were not significantly different between patients with ENL reactions and LL controls before treatment. Interestingly, while the percentage of naive B-cells was significantly lower in untreated ENL patients than in LL patient controls, the percentage of activated memory B-cells was significantly higher in these untreated ENL patients than in LL controls. On the other hand, the percentage of tissue-like memory B-cells was considerably low in untreated ENL patients compared to LL controls. It appears that the lower frequency of tissue-like memory B-cells in untreated ENL could promote the B-cell/T-cell interaction in these patients through downregulation of inhibitory molecules unlike in LL patients. Conversely, the increased production of activated memory B-cells in ENL patients could imply the scale up of immune activation through antigen presentation to T-cells. However, the generation and differential function of these memory B-cells need further investigation. The finding of increased percentage of activated memory B-cells in untreated patients with ENL reactions suggests the association of these cells with the ENL pathology. The mechanism by which inflammatory reactions like ENL affecting these memory cells and contributing to the disease pathology is an interesting area to be explored for and could lead to the development of novel and highly efficacious drug for ENL treatment

Exposure to household air pollution from solid cookfuels and childhood stunting: a population-based, cross-sectional study of half a million children in low- and middle-income countries

BACKGROUND: Household air pollution from the incomplete combustion of solid cookfuels in low- and middle-income countries (LMICs) has been largely ignored as a potentially important correlate of stunting. Our objective was to examine the association between solid cookfuel use and stunting in children aged <5 y. METHODS: We used data from 59 LMICs' population-based cross-sectional demographic and health surveys; 557 098 children aged <5 y were included in our analytical sample. Multilevel logistic regression was used to examine the association between exposure to solid cookfuel use and childhood stunting, adjusting for child sex, age, maternal education and number of children living in the household. We explored the association across key subgroups. RESULTS: Solid cookfuel use was associated with child stunting (adjusted OR 1.58, 95% CI 1.55 to 1.61). Children living in households using solid cookfuels were more likely to be stunted if they lived in rural areas, the poorest households, had a mother who smoked tobacco or were from the Americas. CONCLUSIONS: Focused strategies to reduce solid cookfuel exposure might contribute to reductions in childhood stunting in LMICs. Trial evidence to assess the effect of reducing solid cookfuel exposure on childhood stunting is urgently needed

Assess Farmer’s Skills on Chickpea (Cicer arietinum (L.) Seed Qualities and its Components in East showa Zone, Ethiopia

In Ethiopia, chickpea is an important grain legume next to faba bean and common bean both in terms of area coverage and production. It is mainly grown as a source of food protein, income generation, and soil fertility restoration and used for animal feed. Quality seed production and associated technologies could be mentioned among the major challenges that limit chickpea production and productivity in Ethiopia. This study was therefore conducted to investigate the experiences and perception of farmers regarding chickpea seed quality. Two representative districts (Ada and Lume) were systematically selected from the major chickpea growing area. 84 seed producers were randomly selected from the districts and interviewed to gather information on perception and experience of chickpea seed production systems. The survey result indicated high adoption rate for improved chickpea varieties in the study areas. Arerti and Habru were among the dominant and widely grown chickpea varieties in the districts. Half of the farmers in the study area experienced that seed quality test are mandatory process in the seed production systems.In the study area, disease is as a major challenge for chickpea seed production so; the seed regulatory unit should consider future work associated to seed health

Assessment of seed quality parameters in different seed sources of chickpea (Cicer arietinum (L.)

In Ethiopia, chickpea is an important grain legume next to faba bean and common bean. Quality seed production and associated technologies could be mentioned among the major challenges that limit chickpea production and productivity in Ethiopia. This study was conducted to assess the quality of seeds at different generation classes as obtained from various sources that would contribute an estimate of more than half the chickpea seed suppliers. Thirty one seed samples taken from ten different formal seed sources and four seed classes were used to test physical, physiological and seed health parameters. The result of the laboratory study indicated that seed sources and classes have affected highly significantly the moisture content and hundred seed weight. Correlation analysis showed that seed purity had positive and highly significantly influenced standard germination, vigor index, seedling dry weight and hundred seed weight. Similarly, vigor index was correlated positively and highly significantly with speed of standard germination and root length. Considering seed health as standard quality parameters showed that no seed sources and classes met the standards set by the national seed quality. The seed regulatory unit should be considered in the future in enhancing the seed standard levels and on undermined factors associated to seed health