116 research outputs found

    Direct coupling of a free-flow isotachophoresis (FFITP) device with electrospray ionization mass spectrometry (ESI-MS)

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    We present the online coupling of a free-flow isotachophoresis (FFITP) device to an electrospray ionization mass spectrometer (ESI-MS) for continuous analysis without extensive sample preparation. Free-flow-electrophoresis techniques are used for continuous electrophoretic separations using an electric field applied perpendicular to the buffer and sample flow, with FFITP using a discontinuous electrolyte system to concurrently focus a target analyte and remove interferences. The online coupling of FFITP to ESI-MS decouples the separation and detection timeframe because the electrophoretic separation takes place perpendicular to the flow direction, which can be beneficial for monitoring (bio)chemical changes and/or extensive MSn studies. We demonstrated the coupling of FFITP with ESI-MS for simultaneous concentration of target analytes and sample clean-up. Furthermore, we show hydrodynamic control of the fluidic fraction injected into the MS, allowing for fluidically controlled scanning of the ITP window. Future applications of this approach are expected in monitoring biochemical changes and proteomics151734953502FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2013/06625-2; 2011/02477-3Alexander von Humboldt Foundation; Central European Institute of Technology (CEITEC

    Solving multi-structured problems by introducing linkage kernels into GOMEA

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    Model-Based Evolutionary Algorithms (MBEAs) can be highly scalable by virtue of linkage (or variable interaction) learning. This requires, however, that the linkage model can capture the exploitable structure of a problem. Usually, a single type of linkage structure is attempted to be captured using models such as a linkage tree. However, in practice, problems may exhibit multiple linkage structures. This is for instance the case in multi-objective optimization when the objectives have different linkage structures. This cannot be modelled sufficiently well when using linkage models that aim at capturing a single type of linkage structure, deteriorating the advantages brought by MBEAs. Therefore, here, we introduce linkage kernels, whereby a linkage structure is learned for each solution over its local neighborhood. We implement linkage kernels into the MBEA known as GOMEA that was previously found to be highly scalable when solving various problems. We further introduce a novel benchmark function called Best-of-Traps (BoT) that has an adjustable degree of different linkage structures. On both BoT and a worst-case scenario-based variant of the well-known MaxCut problem, we experimentally find a vast performance improvement of linkage-kernel GOMEA over GOMEA with a single linkage tree as well as the MBEA known as DSMGA-II

    Methodologies in Development Studies:An Overview

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    The interdisciplinary nature of the field of Development Studies (DS) makes it hard to point towards a ‘signature’ methodology. Different development challenges bring different ideas about what the problem is (ontology) and how researchers can know about it (epistemology), as well as different research methods. The rationale for choosing a method can be ideological or pragmatic. In the field of DS, this often entails knowing what methods research commissioners see as credible and what types of evidence they find persuasive. The weight placed on the data generated by certain methods and the lack of critical attention to how it was actually produced shows the importance of a focus on methodology. In looking at, or for, the defining methodologies of DS, this chapter focuses on methodology in a relatively narrow sense: what types of sample and what combinations of methods are typically used by researchers within DS to construct credible arguments around questions of policy or practice. It describes which methodologies constitute the bulk of DS research through analysis of projects and outputs. Finally, it asks what people who generate and use DS research could do to increase its rigour and relevance (Gujit and Roche, 2014; see also Oswald, Leach and Gaventa, this volume) and how the political economy of development research funding might militate against this

    Photolithographic patterning of conducting polyaniline films via flash welding

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    In this work, two significant advances in photolithographic patterning of polyaniline (PANI) films are reported. Firstly, flash welding was enhanced through the use of polymeric substrates, enabling complete penetration of the welding of PANI films with thicknesses ranging from 5 to over 14 mu m, significantly thicker than reported previously. Masking of parts of the PANI films during flash welding enabled the formation of adjacent conducting and insulating regions as the welding changes the electrical properties of the film. Raman spectroscopy was used to determine the sharpness of these edges, and indicated that the interface between the flash welded and masked regions of the PANI films was typically less than 15 mu m wide. Secondly, using longpass filters, light with a wavelength less than 570 nm was found not to contribute to the welding process. This was confirmed by the use of a 635 nm laser diode for welding the PANI films. This novel approach enabled patterning of PANI films using a direct writing technique with a narrow wavelength light source

    Ventilator-associated pneumonia in children after cardiac surgery in The Netherlands

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    We conducted a retrospective cohort study in an academic tertiary care center to characterize ventilator-associated pneumonia (VAP) in pediatric patients after cardiac surgery in The Netherlands. All patients following cardiac surgery and mechanically ventilated for ≥24 h were included. The primary outcome was development of VAP. Secondary outcomes were duration of mechanical ventilation and length of ICU stay. A total of 125 patients were enrolled. Their mean age was 16.5 months. The rate of VAP was 17.1/1,000 mechanical ventilation days. Frequently found organisms were Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and Pseudomonas aeruginosa. Patients with VAP had longer duration of ventilation and longer ICU stay. Risk factors associated with the development of VAP were a PRISM III score of ≥10 and transfusion of fresh frozen plasma. The mean VAP rate in this population is higher than that reported in general pediatric ICU populations. Children with VAP had a prolonged need for mechanical ventilation and a longer ICU sta

    Beliefs, taboos and minor crop value chains: the case of Bambara Groundnut in Malawi

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    Throughout sub-Saharan Africa, bambara groundnut (Vigna subterranean) is a source of food for smallholder farmers that is increasingly promoted for its drought tolerance, soil enhancing qualities and nutritious properties. Being an accessible crop to smallholders, it has also recently been the focus of support to develop its value chain in Malawi. However, bambara groundnut is featured in the belief systems of rural people in Malawi, and may effect and be effected by market development. Beliefs and taboos reflect the life/death meanings symbolically represented in bambara groundnut, which influences how and by whom the crop is produced and consumed. These practices lend significant control over the crop to women. These findings have important implications for development and market related interventions that work with food crops, which need to be taken into account during the design phase

    Van de Graaff generator for capillary electrophoresis

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    A new approach for high voltage capillary electrophoresis (CE) is proposed, which replaces the standard high voltage power supply with a Van de Graaff generator, a low current power source. Because the Van de Graaff generator is a current-limited source (10 μA), potentials exceeding 100 kV can be generated for CE when the electrical resistance of the capillary is maximized. This was achieved by decreasing the capillary diameter and reducing the buffer ionic strength. Using 2 mM borate buffer and a 5 μm i.d. capillary, fluorescently labeled amino acids were separated with efficiencies up to 3.5 million plates; a 5.7 fold improvement in separation efficiency compared to a normal power supply (NPS) typically used in CE. This separation efficiency was realized using a simple set-up without significant Joule heating, making the Van de Graaff generator a promising alternative for applying the high potentials required for enhancing resolution in the separation and analysis of highly complex samples, for example mixtures of glycans

    Initial microbial spectrum in severe secondary peritonitis and relevance for treatment

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    This study aims to determine whether abdominal microbial profiles in early severe secondary peritonitis are associated with ongoing infection or death. The study is performed within a randomized study comparing two surgical treatment strategies in patients with severe secondary peritonitis (n = 229). The microbial profiles of cultures retrieved from initial emergency laparotomy were tested with logistic regression analysis for association with ‘ongoing infection needing relaparotomy’ and in-hospital death. No microbial profile or the presence of yeast or Pseudomonas spp. was related to the risk of ongoing infection needing relaparotomy. Resistance to empiric therapy for gram positive cocci and coliforms was moderately associated with ongoing abdominal infection (OR 3.43 95%CI 0.95–12.38 and OR 7.61, 95%CI 0.75–76.94). Presence of only gram positive cocci, predominantly Enterococcus spp, was borderline independently associated with in-hospital death (OR 3.69, 95%CI 0.99–13.80). In secondary peritonitis microbial profiles do not predict ongoing abdominal infection after initial emergency laparotomy. However, the moderate association of ongoing infection with resistance to the empiric therapy compels to more attention for resistance when selecting empiric antibiotic coverage

    Social learning in LEADER: Exogenous, endogenous and hybrid evaluation in rural development

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    This paper considers the relationship between the centralised exogenous, institutions and the embedded, endogenous institutions of rural governance in Europe through an examination the evaluation procedures of the European LEADER programme. LEADER is presented in the literature as progressive in terms of innovation and stakeholder engagement. Yet while the planning and management of LEADER embraces heterogeneity and participation, programmatic evaluation is centralised and held at arms length from delivery organisations. The paper reviews previous efforts to improve evaluation in LEADER and considers alternative strategies for evaluation, contrasting LEADER practice with participatory evaluation methodologies in the wider international context. Can evaluation in itself be valuable as a mode of social learning and hence a driver for endogenous development in rural communities in Europe? The paper concludes by examining the challenges in producing a hybrid form of evaluation which accommodates endogenous and exogenous values
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