278 research outputs found

    Centre-commissioned external review of ILRI’s capacity strengthening strategy, role and activities

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    Smallholder dairy production and marketing—Opportunities and constraints

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    Photophysics of some styryl thiazolo quinoxaline dyes in organic media

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    The photophysics of a new class of styryl dyes, 2-styryl thiazolo quinoxaline (STQ) based structures was investigated in organic solvents and organized molecular assemblies. The absorption, steady state and time-resolved fluorescence characteristics of the STQ dyes in low-viscosity organic solvents are consistent with a single species in the ground and excited state. The one electron electrochemical oxidation and reduction potentials of the dyes are within ±1V vs. NHE. The spectral shifts of the dyes in organic solvents are linearly correlated with the variation of solvent polarity parameters. The dipole moments in the ground and excited state of the dyes were calculated without assuming a value for the cavity radius. The temperature dependence of the nonradiative rate of STQ dye in DMSO indicated an activation barrier (ΔE=10.7 kJ/mol) which is comparable to the activation energy (Ea=13.7 kJ/mol) of viscous friction in DMSO. In dichloromethane, the activation barrier is 34.0 kJ/mol which is very high compared to Ea=6.64 kJ/mol. Formation of a dye–solvent complex is suggested in dichloromethane. The fluorescence decay of STQ dye is multiexponential in a viscous solvent (2-octanol) or when bound to a protein (Lysozyme), micelle or lipid membrane. In 2-octanol, the decay parameters are wavelength dependent and the results are consistent with the mechanism of excited state kinetics of solvent relaxation. In other systems, the multiexponential decay is due to multiple sites of solubilization of the dye in the organized molecular assembly

    Can We Picture Equity? Critically Examining Cross-Cultural Short-Term Project Collaborations

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    This paper explores equity challenges common to short-term cross-cultural research partnerships. We focus on a project-based activity in which U.S. undergraduate students and college faculty taught middle-school students in Goa, India how to make podcasts about complex environmental problems. Project team members conducted a collaborative auto-ethnography focused on questions of power, leadership, collaboration, and equity, and examined exit-interview photo elicitation data to identify the core challenges of ethical and equitable short-term cross-cultural research and programming. Our use of photographs as conversation prompts helped to highlight contradictions and asymmetries along axes of power, cultural imperialism, knower-knowledge, age, race/ethnicity, social class, and gender. We reflect on possibilities for educational research that rejects a “voluntourism” model and moves, if imperfectly, toward more equitable international collaborations

    A performance comparison of zone-based multicast protocols for mobile ad hoc networks

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    With the current trend toward ubiquitous computing come wireless devices capable of forming the nodes of mobile ad hoc networks. Such networks typically rely on routing protocols in order to communicate messages from a source node to a destination node through a set of intermediary nodes. In a typical ad hoc environment, mobile nodes mostly work as a group and are involved in collaborative computing. Multicast communication is more effective in these scenarios. This paper presents the comparison of the performance of two zone-based multicast routing protocols. Shared-tree MZR is a shared tree variant of the Multicast Routing Protocol based on Zone Routing (MZR). We compare the two variants and analyze their performance under various network conditions. The test results show that Shared-tree MZR protocol performs well and has significantly low overhead in scenarios with multiple sources. ©2003 IEEE

    A zone-based shared-tree multicast protocol for mobile ad hoc networks

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    This paper proposes a new multicast protocol for mobile ad hoc networks (MANETs). The proposed protocol, Shared-Tree MZR, is a shared tree variant of the Multicast Routing Protocol based on Zone Routing (MZR). The concept of zone-based multicast routing for mobile ad hoc networks was originally proposed in MZR. The new protocol utilizes the advantages of the shared-tree together with the advantages of the zone-based routing. The performance of the protocol is analyzed for various network conditions. The test results show that the new protocol performs well and has significantly low overhead in scenarios with multiple sources

    N-Aryl-linked spirocyclic polymers for membrane separations of complex hydrocarbon mixtures

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    The fractionation of crude-oil mixtures through distillation is a large-scale, energy-intensive process. Membrane materials can avoid phase changes in such mixtures and thereby reduce the energy intensity of these thermal separations. With this application in mind, we created spirocyclic polymers with N-aryl bonds that demonstrated noninterconnected microporosity in the absence of ladder linkages. The resulting glassy polymer membranes demonstrated nonthermal membrane fractionation of light crude oil through a combination of class- and size-based “sorting” of molecules. We observed an enrichment of molecules lighter than 170 daltons corresponding to a carbon number of 12 or a boiling point less than 200°C in the permeate. Such scalable, selective membranes offer potential for the hybridization of energy-efficient technology with conventional processes such as distillation

    Atrial fibrillation in Indigenous and non-Indigenous Australians: a cross-sectional study

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    Published 24 October 2014Objective: To examine the prevalence of atrial fibrillation (AF) and cardiac structural characteristics in Indigenous and non-Indigenous Australians. Design: Retrospective cross-sectional study linking clinical, echocardiography and administrative databases over a 10-year period. Setting: A tertiary, university teaching hospital in Adelaide, Australia. Participants: Indigenous and non-Indigenous Australians. Main outcome measures: AF prevalence and echocardiographic characteristics. Results: Indigenous Australians with AF were significantly younger compared to non-Indigenous Australians (55±13 vs 75±13 years, p<0.001). As a result, racial differences in AF prevalence and left atrial diameter varied according to age. In those under 60 years of age, Indigenous Australians had a significantly greater AF prevalence (2.57 vs1.73%, p<0.001) and left atrial diameters (39±7 vs 37±7 mm, p<0.001) compared to non-Indigenous Australians. In those aged 60 years and above, however, non- Indigenous Australians had significantly greater AF prevalence (9.26 vs 4.61%, p<0.001) and left atrial diameters (39±7 vs 37±7 mm, p<0.001). Left ventricular ejection fractions were less in Indigenous Australians under 60 years of age (49±14 vs 55±11%, p<0.001) and not statistically different in those aged 60 years and above (47±11 vs 52±13, p=0.074) compared to non-Indigenous Australians. Despite their younger age, Indigenous Australians with AF had similar or greater rates of cardiovascular comorbidities than non-Indigenous Australians with AF. Conclusions: Young Indigenous Australians have a significantly greater prevalence of AF than their non- Indigenous counterparts. In contrast, older non- Indigenous Australians have a greater prevalence of AF compared to their Indigenous counterparts. These observations may be mediated by age-based differences in comorbid cardiovascular conditions, left atrial diameter and left ventricular ejection fraction. Our findings suggest that AF is likely to be contributing to the greater burden of morbidity and mortality experienced by young Indigenous Australians. Further study is required to elucidate whether strategies to prevent and better manage AF in Indigenous Australians may reduce this burden.Christopher X Wong, Anthony G Brooks, Yi-Han Cheng, Dennis H Lau, Geetanjali Rangnekar, Kurt C Roberts-Thomson, Jonathan M Kalman, Alex Brown, Prashanthan Sander

    Saliva microRNA Biomarkers of Cumulative Concussion

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    Recurrent concussions increase risk for persistent post-concussion symptoms, and may lead to chronic neurocognitive deficits. Little is known about the molecular pathways that contribute to persistent concussion symptoms. We hypothesized that salivary measurement of microribonucleic acids (miRNAs), a class of epitranscriptional molecules implicated in concussion pathophysiology, would provide insights about the molecular cascade resulting from recurrent concussions. This hypothesis was tested in a case-control study involving 13 former professional football athletes with a history of recurrent concussion, and 18 age/sex-matched peers. Molecules of interest were further validated in a cross-sectional study of 310 younger individuals with a history of no concussion (n = 230), a single concussion (n = 56), or recurrent concussions (n = 24). There was no difference in neurocognitive performance between the former professional athletes and their peers, or among younger individuals with varying concussion exposures. However, younger individuals without prior concussion outperformed peers with prior concussion on three balance assessments. Twenty salivary miRNAs differed (adj. p \u3c 0.05) between former professional athletes and their peers. Two of these (miR-28-3p and miR-339-3p) demonstrated relationships (p \u3c 0.05) with the number of prior concussions reported by younger individuals. miR-28-3p and miR-339-5p may play a role in the pathophysiologic mechanism involved in cumulative concussion effects
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