4,930 research outputs found

    Ontwikkeling en implementatie van geïntegreerde bestrijding in zomerbloemen : toepassing van beschikbare producten en ontwikkeling van nieuwe natuurlijke vijanden

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    In 2008 en 2009 werden loslatingen verricht van de roofmijten Neoseiulus cucumeris en Amblyseius andersoni, soms aangevuld met Phytoseiulus persimilis, in de zomerbloemen rozenbottel, chrysant, Veronica, Alchemilla en Delphinium. Hierbij bleek dat roofmijten zich niet in alle gewassen in gelijke mate vestigen. In Alchemilla en Delphinium bleek al spontaan Neoseiulus cucumeris voor te kunnen komen. Als in deze gewassen nog geen roofmijten voorkomen, zal introductie van N. cucumeris zeker slagen, mits er geen breedwerkende middelen worden toegepast. Vooral Alchemilla bleek een goede roofmijtenplant te zijn. Behalve Neoseiulus cucumeris werden ook andere soorten gevonden. Roofmijten die in de handel zijn tegen spint, Phytoseiulus persimilis en Neoseiulus californicus, vestigen zich eveneens goed in dit gewas, in tegenstelling tot Amblyseius andersoni. Verder kunnen spontaan andere natuurlijke vijanden van plagen voorkomen: roofwantsen, gaasvliegen en galmuggen. Trips nam in beide jaren af gedurende de teelt of bleef op een laag niveau. Neoseiulus alpinus is een roofmijt, die eerder is verzameld van Alchemilla en in kweek genomen. Een loslating van deze roofmijt in Alchemilla slaagde in 2008 niet, maar in 2009 wel. In Delphinium was in 2008 vanaf het begin van de waarnemingen Neoseiulus cucumeris in het gewas aanwezig. Na introductie van Amblyseius andersoni werd ook deze soort teruggevonden. Spint kwam in 2008 niet tot ontwikkeling. Buiten de proef kwam plaatselijk cyclamenmijt voor. In 2009 werd in Delphinium zwavel verdampt tegen echte meeldauw. Er was geen goede vestiging van roofmijten in het gewas, ook niet van de roofmijt Phytoseiulus persimilis, waardoor chemische bestrijding van spint noodzakelijk was. In Veronica, chrysant en rozenbottel kwamen in vergelijking met Alchemilla en Delphinium minder roofmijten voor. Trips en spint waren in 2008 en 2009 geen probleem in Veronica, chrysant en rozenbottel. Op rozenbottel kwam zonder introductie Neoseiulus cucumeris voor. Andere soorten roofmijten, die soms spontaan optraden waren Neoseiulus reductus in Delphinium, Amblyseius graminis in Alchemilla en chrysant, en roofmijten die tot een andere groep (Bdelloidea) behoren, met name op chrysant en Veronica

    Numerical simulations of kink instability in line-tied coronal loops

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    The results from numerical simulations carried out using a new shock-capturing, Lagrangian-remap, 3D MHD code, Lare3d are presented. We study the evolution of the m=1 kink mode instability in a photospherically line-tied coronal loop that has no net axial current. During the non-linear evolution of the kink instability, large current concentrations develop in the neighbourhood of the infinite length mode rational surface. We investigate whether this strong current saturates at a finite value or whether scaling indicates current sheet formation. In particular, we consider the effect of the shear, defined by where is the fieldline twist of the loop, on the current concentration. We also include a non-uniform resistivity in the simulations and observe the amount of free magnetic energy released by magnetic reconnection

    Permeability characteristics of human endothelial monolayers seeded on different extracellular matrix proteins.

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    OBJECTIVE: To investigate whether endothelial monolayer permeability changes induced by inflammatory mediators are affected by the extracellular matrix protein used for cell seeding. METHODS: Human umbilical venular endothelial cells (HUVEC) were grown to confluent monolayers on membranes coated with either collagen, fibronectin or gelatin. The permeability to albumin and dextran was then assessed, both under normal conditions and after treatment with tumor necrosis factor-alpha (TNF-alpha) and bacterial lipopolysaccharide (LPS). RESULTS: With any of the three protein coatings, tight junctions were formed all over the monolayers. The permeability of the coated membranes to albumin and dextran was reduced strongly by confluent monolayers; the relative reduction was similar for the three matrix proteins used. Pre-incubation of the monolayers with either TNF-alpha or LPS increased permeability dose dependently. However, the relative increase due to either treatment was independent of the protein used for membrane coating. CONCLUSION: The extracellular matrix protein used for initial seeding of endothelial cultures plays a minor role in determining the permeability changes induced in HUVEC monolayers by inflammatory mediators

    Exploring Research through Design in Animal-Computer Interaction

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    This paper explores Research through Design (RtD) as a potential methodology for developing new interactive experiences for animals. We present an example study from an on-going project and examine whether RtD offers an appropriate framework for developing knowledge in the context of Animal-Computer Interaction, as well as considering how best to document such work. We discuss the design journey we undertook to develop interactive systems for captive elephants and the extent to which RtD has enabled us to explore concept development and documentation of research. As a result of our explorations, we propose that particular aspects of RtD can help ACI researchers gain fresh perspectives on the design of technology-enabled devices for non-human animals. We argue that these methods of working can support the investigation of particular and complex situations where no idiomatic interactions yet exist, where collaborative practice is desirable and where the designed objects themselves offer a conceptual window for future research and development

    Work engagement, emotional exhaustion, and OCB-civic virtue among nurses: a multilevel analysis of emotional supervisor support

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    Introduction: This study investigates the moderating role of supervisor emotional support at the group level on the relationship between emotional exhaustion and work engagement with organizational citizenship behavior-civic virtue (OCB-civic virtue) at the individual level among nurses. Method: A cross-sectional study was carried out on 558 nurses nested in 36 working units from two hospitals in Algiers. A multilevel analysis using Hierarchical Linear Modeling was performed. Results: Results show that the positive effect of work engagement on OCB-civic virtue was moderated by supervisor emotional support at group level. The nurses emotional exhaustion and OCB-civic virtue negative relationship at the individual level is buffered by supervisor emotional support at group level. Discussion: In consequence, supervisor emotional support experienced by the team has an influence on the emotional exhaustion and work engagement OCB-civic virtue relationship

    The cost-effectiveness of dapagliflozin compared to DPP-4 inhibitors in the treatment of type 2 diabetes mellitus in the Netherlands

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    Aim: When glycaemic control for people with type 2 diabetes is not achieved with metformin and sulfonylurea alone, adding another oral anti-diabetes drug, such as a sodium–glucose co-transporter 2 (SGLT2) or dipeptidyl peptidase-4 (DPP-4) inhibitor, is an alternative to starting insulin. The aim of this study is to determine the cost-effectiveness of dapagliflozin (an SGLT2 inhibitor) compared with DPP-4 inhibitors when added to metformin and sulfonylurea in people with type 2 diabetes in the Netherlands. Methods: A cost–utility analysis is performed using the Cardiff diabetes model, a fixed-time increment stochastic simulation model informed by ‘United Kingdom Prospective Diabetes Study 68’ risk equations. The base-case analysis uses a 40-year time horizon, a Dutch societal perspective and differential discounting (4% for costs, 1.5% for effects). Inputs are obtained from the literature and Dutch price lists. Univariate and probabilistic sensitivity analysis are performed. Results: Dapagliflozin is dominant compared with DPP-4 inhibitors, resulting in a €990 cost saving and a 0.28 quality-adjusted life year gain over 40 years. Cost savings are associated mainly with treatment costs and a reduced incidence of micro- and macrovascular complications, among others nephropathy, myocardial infarction and stroke. Results are robust to changes in input parameters. Conclusions: Dapagliflozin is a cost-saving alternative to DPP-4 inhibitors when added to metformin and sulfonylurea. The incidence of micro- and macrovascular complications is lower for people treated with dapagliflozin. Uncertainty around this outcome is low

    Inverted and Programmable Poynting Effects in Metamaterials

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    The Poynting effect generically manifests itself as the extension of the material in the direction perpendicular to an applied shear deformation (torsion) and is a material parameter hard to design. Unlike isotropic solids, in designed structures, peculiar couplings between shear and normal deformations can be achieved and exploited for practical applications. Here, we engineer a metamaterial that can be programmed to contract or extend under torsion and undergo nonlinear twist under compression. First, we show that our system exhibits a novel type of inverted Poynting effect, where axial compression induces a nonlinear torsion. Then the Poynting modulus of the structure is programmed from initial negative values to zero and positive values via a pre-compression applied prior to torsion. Our work opens avenues for programming nonlinear elastic moduli of materials and tuning the couplings between shear and normal responses by rational design. Obtaining inverted and programmable Poynting effects in metamaterials inspires diverse applications from designing machine materials, soft robots and actuators to engineering biological tissues, implants and prosthetic devices functioning under compression and torsion.Comment: 9 pages, 6 figure
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