Effect of low density lipoprotein on adenosine receptor-mediated coronary vasorelaxation in vitro

We investigated the effect of low density lipoprotein (LDL) on vasorelaxations and nitric oxide generation induced by the adenosine analogs, 5'-(N-ethylcarboxamide)adenosine, 2-p-(2-carboxyethyl)phenylethyl-amino-5'N-ethylcarboxamidoadenosine and/or 2-chloroadenosine in porcine coronary artery rings in vitro. Preincubation of tissues with native LDL (100 and 200 microg/ml) for 4 hr in the absence or presence of copper sulfate (5 microM) selectively attenuated the endothelium-dependent relaxations elicited by 5'-(N-ethylcarboxamide)adenosine and 2-p-(2-carboxyethyl)phenylethyl-amino-5'N-ethylcarboxamideoadenosine+ ++ without altering the response to 2-chloroadenosine which produced endothelium-independent relaxation. The 4-hr exposure of tissues to native LDL (100 microg/ml) also inhibited the production of nitrite induced by 5'-(N-ethylcarboxamide)adenosine in endothelium-intact rings. These effects were associated with enhanced oxidation of the lipoprotein. The inhibitory action of LDL on tissue relaxations and nitrite generation as well as the oxidation of the lipoprotein were all prevented by high density lipoprotein (100 microg/ml). In contrast, a relatively short period (20 min) of tissue incubation with native LDL produced no alterations of the relaxations and nitrite production evoked by 5'-(N-ethylcarboxamide)adenosine and 2-p-(2-carboxyethyl)phenylethyl-amino-5'N-ethylcarboxamidoadenosine. Under this condition, the oxidation of LDL was not also significantly altered. In conclusion, the results indicate that in coronary artery LDL, with oxidative modification, causes attenuation of nitric oxide-mediated endothelial responses induced by adenosine receptors activation, and this effect is prevented by high density lipoprotein. Such modulation may be of importance in hypercholesterolemia and in the development of atherosclerosis.     

Food insecurity,school absenteeism and educational attainment of adolescents in Jimma Zone Southwest Ethiopia: a longitudinal study

Background  

Food insecurity not only affects physical growth and health of children but also their intellectual development, school attendance and academic performance. However, most evidences are based on studies in high income countries. Although food insecurity is common in Ethiopia, to what extent it affects school attendance and educational attainment of adolescents is not explored. We hypothesized that food insecure adolescents would be more likely to be absent from school and have lower grades attained after 1 year compared to their food secure peers.     

Land-use and land-cover change and its environmental implications in a tropical highland watershed,Ethiopia

This study analysed long-term land-use and land-cover change (LUCC) in a highland watershed covering an area of about 154?km² in the Blue Nile basin of Ethiopia. Two sets of panchromatic aerial photographs (1957 and 1982) and a Landsat TM image (2001) were the main input data from which three land-use and land-cover maps were produced by employing geographical information systems/remote sensing techniques. These data were complemented by some socio-economic data that were generated by using household survey, key-informant interview and group discussion methods. The results show that in regard to land-use and land-cover, the major change has been the reduction of areas under natural vegetation cover and expansion of open grassland, cultivated areas and settlements. Over the four and a half decades considered, areas of forest and dense tree cover and shrub grassland decreased by 64 and 6%, respectively. Forest and dense tree cover experienced the greatest change; from accounting for ～9% of the total area of the watershed in 1957 to only ～3% in 2001. In general, much of the de-vegetation occurred between 1982 and 2001. Cropland and rural settlement showed a small but consistent increase between 1957 and 2001. Riparian vegetation decreased during the first period, but increased almost to the same level during the second period by gaining land from the other land-use and land-cover types. The observed LUCCs were driven by a combination of proximate and underlying causes. These include increasing demographic pressure and associated demands on environmental resources, widespread rural poverty and inadequate management of common property resources owing to poorly defined ownership arrangements. There is a need for short-term and long-term strategies to ensure sustainable land management and agricultural development in the watershed.     

A tractable approximation of non-convex chance constrained optimization with non-Gaussian uncertainties

Chance constrained optimization problems in engineering applications possess highly nonlinear process models and non-convex structures. As a result, solving a nonlinear non-convex chance constrained optimization (CCOPT) problem remains as a challenging task. The major difficulty lies in the evaluation of probability values and gradients of inequality constraints which are nonlinear functions of stochastic variables. This article proposes a novel analytic approximation to improve the tractability of smooth non-convex chance constraints. The approximation uses a smooth parametric function to define a sequence of smooth nonlinear programs (NLPs). The sequence of optimal solutions of these NLPs remains always feasible and converges to the solution set of the CCOPT problem. Furthermore, Karush–Kuhn–Tucker (KKT) points of the approximating problems converge to a subset of KKT points of the CCOPT problem. Another feature of this approach is that it can handle uncertainties with both Gaussian and/or non-Gaussian distributions.     

Measurement of caffeine in coffee beans with UV/vis spectrometer

In this research work using UV/vis spectrophotometer the molar decadic absorption coefficients and transitional dipole moment of pure caffeine in water and dichloromethane were obtained at 272 and 274.7 nm. The molar decadic absorption coefficients of caffeine in water and dichloromethane at these wavelengths are 1115 and 1010 m² mol⁻¹, respectively. The calculated values for the transitional dipole moment of caffeine in water and in dichloromethane are 10.40 × 10⁻³⁰ and 10.80 × 10⁻³⁰ C m, respectively. After characterizing caffeine in water and dichloromethane, fast and simple methods were developed that enable to quantify the content of caffeine in coffee beans. The methods helped in extracting caffeine from coffee dissolved in water by dichloromethane, and Gaussian fit was applied to eliminate the possible interference with the caffeine spectra.     

Cumulative impacts of river engineering,Mississippi and Lower Missouri rivers

The goal of this study was to construct a large, data‐rich model to test hydrological responses to engineering modifications on over 3200 km of the Mississippi and Lower Missouri Rivers. We compiled model explanatory variables from a geospatial database quantifying construction of all bridges, wing dikes, bendway weirs, levees, artificial meander cutoffs, channel constriction and navigational dams over the past 100–150 years. Response variables were derived from 68 rated and un‐rated hydrologic stations in the study area, with responses analysed across a range of discharges from within‐channel flows up to moderate floods. Correlation analysis, multiple linear regression and stepwise regression analyses document strong and consistent responses to construction history, both in individual reach‐scale models and systemwide. Meander cutoffs are associated with degradation and acceleration of flow that has reduced stages across the full discharge range. Navigational dams on the Upper Mississippi River increased low‐flow stages and flood levels to a lesser extent, with little or no post‐dam change. One of the strongest signals was the hydrologic response to wing‐dike construction, which resulted in large back‐water increases in stage upstream of wing dikes and mixed effects downstream, including the overlapping effects of incision and velocity losses. Levees were associated with local flow concentration, overbank storage loss and floodplain conveyance loss depending on reach‐scale conditions. The results presented here (1) quantify incremental and cumulative hydrologic responses to a range of engineering activities and (2) provide an empirical tool for verifying and assessing hydraulic and other models of river‐system change. Copyright © 2009 John Wiley & Sons, Ltd.     

Inorganic heterogeneous catalysts for biodiesel production from vegetable oils

Biofuels are renewable solutions to replace the ever dwindling energy reserves and environmentally pollutant fossil liquid fuels when they are produced from low cost sustainable feedstocks. Biodiesel is mainly produced from vegetable oils or animal fats by the method of transesterification reaction using catalysts. Homogeneous catalysts are conventionally used for biodiesel production. Unfortunately, homogeneous catalysts are associated with problems which might increase the cost of production due to separation steps and emission of waste water. Inorganic heterogeneous catalysts are potentially low cost and can solve many of the problems encountered in homogeneous catalysts. Many solid acid and base inorganic catalysts have been studied for the transesterification of various vegetables oils. The work of many researchers on the development of active, tolerant to water and free fatty acids (FFA), as well as stable inorganic catalysts for biodiesel production from vegetable oils are reviewed and discussed.     

Measurement of integrated absorption cross-section,oscillator strength and number density of caffeine in coffee beans by integrated absorption coefficient technique

Integrated absorption cross-section and oscillator strength of caffeine in water and dichloromethane were reported by UV–Vis spectrometer in the wave number regions of 20,000–39,062 cm⁻¹ at room temperature. The integrated absorption cross-section of caffeine in water and dichloromethane in these wave number regions were (4.44 ± 0.18) × 10⁷ and (4.32 ± 0.11) × 10⁷ L mol⁻¹ cm⁻², respectively. The corresponding calculated value for oscillator strength of caffeine in water and dichloromethane were 0.19 ± 0.01 and 0.18 ± 0.01, respectively. In addition number densities of caffeine in different coffee beans were reported using integrating absorption coefficient technique. The calculated number density of caffeine for different coffee varieties were varying from (3.53–4.76) × 10⁻⁵ mol L⁻¹. The new applied technique has an advantage over other techniques in that it provides additional information about the nature of the absorbing molecules and establishes accurate evaluation of the UV–Vis absorption intensity.