404 research outputs found

    Evaluating Ethiopia’s Development Progress

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    Ethiopia, Africa’s second most-populated nation is well on its way to becoming one of its wealthiest nations as it charges forward on its path to development. The big question is whether this growth is sustainable. To tackle this question, we will discuss its development strategy using a popular comparison to that of China. We will then offer an appraisal of the current state of the country. Finally, we will evaluate the future of Ethiopia, as it continues its current path – evaluating the potential upsides and risks it faces moving forward

    Actividad antioxidante de extractos de torta de aceite de semilla de Sclerocarya birrea

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    The antioxidant activity of methanolic extracts from Sclerocarya birrea kernel oil meal, extracted using two different methods was evaluated. The extraction was carried out using magnetic stirring of the material in methanol/water (80:20 v/v) overnight followed by two ultra-sonic treatments for 45 min. (Overnight extract, ONEXT) and three ultra-sonic treatments for 45 min. only (Ultra-sonic extract, USEXT), respectively. Three fractions were obtained from each extract and the contents of total phenolic compounds were determined in each fraction according to the Folin-Ciocalteau method as 34.6, 54.8, and 58.6 mg/g of dry product in ONEXT and 29.6, 84.8, 143.9 mg/g in USEXT, respectively. The antioxidant activity of the extracts was evaluated according to the β-carotene-linoleic acid assay, where the extracts and their fractions showed significant effect (pSe ha evaluado la actividad antioxidante de extractos metanólicos de torta de aceite de semilla de Sclerocarya birrea extraídos usando dos métodos diferentes. La extracción se llevó a cabo mediante agitación magnética del material en metanol/agua (80:20 v/v) durante toda la noche seguida de dos tratamientos con ultrasonidos durante 45 min. (extracto ONEXT) y solo tres tratamientos con ultrasonidos durante 45 min. (extracto USEXT), respectivamente. Se obtuvieron tres fracciones de cada extracto y el contenido total de compuestos fenólicos se determinó en cada fracción según el método de Folin-Ciocalteau como 34.6, 54.8 y 58.6 mg/g de producto seco en ONEXT y 29.6, 84.8 y 143.9 mg/g en USEXT, respectivamente. La actividad antioxidante de los extractos fue evaluada mediante el ensayo del β-carotenoácido linoleico donde los extractos y sus fracciones mostraron efectos significativos (

    Vida útil de los aceites de cactus marroquí (Opuntia ficus-indica) y de argán (Argania spinosa). Estudio comparativo

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    Cactus seed oil is gaining considerable popularity in the cosmetic industry. To estimate cactus seed oil’ industrial as well as domestic ease of use, we investigated the oxidative stability of Moroccan cactus seed oil under accelerated aging conditions. In addition, we compared cactus seed oil stability to that of argan oil, a popular and well-established cosmetic oil, under the same conditions. Cactus seed oil is much more sensitive to oxidation than argan oil. Its shelf-life can be estimated to be no longer than 6 months at room temperature. Such instability means that the preparation process for cactus oil must be carried out with great care and cactus seed oil needs to be protected once extracted.El aceite de semillas de cactus está ganando considerable popularidad en la industria cosmética. Para estimar la facilidad de uso industrial y doméstico del aceite de semilla de cactus, investigamos la estabilidad oxidativa del aceite de semilla de cactus marroquí en condiciones de envejecimiento acelerado. Además, comparamos, bajo las mismas condiciones, la estabilidad del aceite de semilla de cactus con la del aceite de argán, otro aceite cosmético popular y bien establecido. El aceite de semilla de cactus es mucho más sensible a la oxidación que el aceite de argán. Su vida útil se puede estimar en no más de 6 meses a temperatura ambiente. Tal inestabilidad significa que los procesos preparativos del aceite de cactus deben manejarse con mucho cuidado y el aceite de semilla de cactus debe protegerse una vez extraído

    High coherence photon pair source for quantum communication

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    This paper reports a novel single mode source of narrow-band entangled photon pairs at telecom wavelengths under continuous wave excitation, based on parametric down conversion. For only 7 mW of pump power it has a created spectral radiance of 0.08 pairs per coherence length and a bandwidth of 10 pm (1.2 GHz). The effectively emitted spectral brightness reaches 3.9*10^5 pairs /(s pm). Furthermore, when combined with low jitter single photon detectors, such sources allow for the implementation of quantum communication protocols without any active synchronization or path length stabilization. A HOM-Dip with photons from two autonomous CW sources has been realized demonstrating the setup's stability and performance.Comment: 12 pages, 4 figure

    Amplitude equations near pattern forming instabilities for strongly driven ferromagnets

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    A transversally driven isotropic ferromagnet being under the influence of a static external and an uniaxial internal anisotropy field is studied. We consider the dissipative Landau-Lifshitz equation as the fundamental equation of motion and treat it in 1+11+1~dimensions. The stability of the spatially homogeneous magnetizations against inhomogeneous perturbations is analyzed. Subsequently the dynamics above threshold is described via amplitude equations and the dependence of their coefficients on the physical parameters of the system is determined explicitly. We find soft- and hard-mode instabilities, transitions between sub- and supercritical behaviour, various bifurcations of higher codimension, and present a series of explicit bifurcation diagrams. The analysis of the codimension-2 point where the soft- and hard-mode instabilities coincide leads to a system of two coupled Ginzburg-Landau equations.Comment: LATeX, 25 pages, submitted to Z.Phys.B figures available via [email protected] in /pub/publications/frank/zpb_95 (postscript, plain or gziped

    Intrinsically narrowband pair photon generation in microstructured fibres

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    In this paper we study the tailoring of photon spectral properties generated by four-wave mixing in a birefringent photonic crystal fibre (PCF). The aim is to produce intrinsically narrow-band photons and hence to achieve high non-classical interference visibility and generate high fidelity entanglement without any requirement for spectral filtering, leading to high effective detection efficiencies. We show unfiltered Hong-Ou-Mandel interference visibilities of 77% between photons from the same PCF, and 80% between separate sources. We compare results from modelling the PCF to these experiments and analyse photon purities.Comment: 23 pages, 17 figures, Comments Welcom

    Multimodal nonlinear imaging of atherosclerotic plaques differentiation of triglyceride and cholesterol deposits

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    Cardiovascular diseases in general and atherothrombosis as the most common of its individual disease entities is the leading cause of death in the developed countries. Therefore, visualization and characterization of inner arterial plaque composition is of vital diagnostic interest, especially for the early recognition of vulnerable plaques. Established clinical techniques provide valuable morphological information but cannot deliver information about the chemical composition of individual plaques. Therefore, spectroscopic imaging techniques have recently drawn considerable attention. Based on the spectroscopic properties of the individual plaque components, as for instance different types of lipids, the composition of atherosclerotic plaques can be analyzed qualitatively as well as quantitatively. Here, we compare the feasibility of multimodal nonlinear imaging combining two-photon fluorescence (TPF), coherent anti-Stokes Raman scattering (CARS) and second-harmonic generation (SHG) microscopy to contrast composition and morphology of lipid deposits against the surrounding matrix of connective tissue with diffraction limited spatial resolution. In this contribution, the spatial distribution of major constituents of the arterial wall and atherosclerotic plaques like elastin, collagen, triglycerides and cholesterol can be simultaneously visualized by a combination of nonlinear imaging methods, providing a powerful label-free complement to standard histopathological methods with great potential for in vivo application

    Local and global modes of drug action in biochemical networks

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    It becomes increasingly accepted that a shift is needed from the traditional target-based approach of drug development to an integrated perspective of drug action in biochemical systems. We here present an integrative analysis of the interactions between drugs and metabolism based on the concept of drug scope. The drug scope represents the set of metabolic compounds and reactions that are potentially affected by a drug. We constructed and analyzed the scopes of all US approved drugs having metabolic targets. Our analysis shows that the distribution of drug scopes is highly uneven, and that drugs can be classified into several categories based on their scopes. Some of them have small scopes corresponding to localized action, while others have large scopes corresponding to potential large-scale systemic action. These groups are well conserved throughout different topologies of the underlying metabolic network. They can furthermore be associated to specific drug therapeutic properties
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