35 research outputs found

    Efficacy of catheter-based drug delivery in a hybrid in vitro model of cardiac microvascular obstruction with porcine microthrombi.

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    Microvascular obstruction (MVO) often occurs in ST-elevation myocardial infarction (STEMI) patients after percutaneous coronary intervention (PCI). Diagnosis and treatment of MVO lack appropriate and established procedures. This study focused on two major points by using an in vitro multiscale flow model, which comprised an aortic root model with physiological blood flow and a microfluidic model of the microcirculation with vessel diameters down to 50 Όm. First, the influence of porcine microthrombi (MT), injected into the fluidic microchip, on perfusion was investigated. We found that only of all injected MT were fully occlusive. Second, it could also be shown that the maximal concentration of a dye (representing therapeutic agent) during intracoronary infusion could be increased on average by , when proximally occluding the coronary artery by a balloon during drug infusion. The obtained results and insights enhance the understanding of perfusion in MVO-affected microcirculation and could lead to improved treatment methods for MVO patients

    Effect of Collateral Flow on Catheter-Based Assessment of Cardiac Microvascular Obstruction.

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    Cardiac microvascular obstruction (MVO) associated with acute myocardial infarction (heart attack) is characterized by partial or complete elimination of perfusion in the myocardial microcirculation. A new catheter-based method (CoFI, Controlled Flow Infusion) has recently been developed to diagnose MVO in the catheterization laboratory during acute therapy of the heart attack. A porcine MVO model demonstrates that CoFI can accurately identify the increased hydraulic resistance of the affected microvascular bed. A benchtop microcirculation model was developed and tuned to reproduce in vivo MVO characteristics. The tuned benchtop model was then used to systematically study the effect of different levels of collateral flow. These experiments showed that measurements obtained in the catheter-based method were adversely affected such that collateral flow may be misinterpreted as MVO. Based on further analysis of the measured data, concepts to mitigate the adverse effects were formulated which allow discrimination between collateral flow and MVO

    The Propagation of Shocks Across International Equity Markets: A Microstructure Perspective

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    We study the high-frequency propagation of shocks across international equity markets. We identify intraday shocks to stock prices, liquidity, and trading activity for 12 equity markets around the world based on non-parametric jump statistics at the 5-minute frequency from 1996 to 2011. Shocks to prices are prevalent and large, with regular spillovers across markets – even within the same 5-minute interval. We find that price shocks are predominantly driven by information rather than liquidity. Consistent with the information channel, price shocks do not revert and often occur around macroeconomic news announcements. Liquidity shocks tend to be isolated events that are neither associated with price shocks nor with liquidity shocks on other markets. Our results challenge the widespread view that liquidity plays an important role in the origination and propagation of financial market shocks

    Auchenorrhyncha and Psylloidea collected during the 25th Central European Auchenorrhyncha meeting, Arnhem, The Netherlands (Hemiptera: Auchenorrhyncha and Psylloidea)

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    Die 25. MitteleuropĂ€ische Zikadentagung fand vom 14.-17. September 2018 in Arnheim in den Niederlanden statt. Da es die erste Tagung in den Niederlanden war, wurden Sammelexkursionen in fĂŒnf typische niederlĂ€ndische Landschaften unternommen. Drei der Exkursionsziele befanden sich in neu geschaffenen Schutzgebieten, die sich auf ehemals landwirtschaftlich genutzten FlĂ€chen befinden. Die beiden weiteren Exkursionsziele waren alte, geschĂŒtzte HeideflĂ€chen. Insgesamt konnten 117 Zikadenarten und 6 Psylloidea-Arten nachgewiesen werden. Drei Arten waren neu fĂŒr die Niederlande: Macrosteles spinosus (in dieser Publikation vorgestellt), Kybos abstrusus (monophag an Populus nigra) und Macrosteles sardus (an Epilobium hirsutum). FĂŒr einige seltene Arten konnten neue Fundpunkte ermittelt werden: Kelisia monoceros, Aphrophora major, Stroggylocephalus agrestis, Edwardsiana diversa, E. tersa, Fruticidia bisignata, Ophiola russeola und Psammotettix pallidinervis. Durch die drei Neufunde erhöht sich die Anzahl der bislang in den Niederlanden nachgewiesenen Zikadenarten auf 421. Diese Arbeit zeigt zudem, dass selbst in erst seit kurzem bestehenden Schutzgebieten seltene und interessante Arten nachgewiesen werden können. The 25th Central European Auchenorrhyncha meeting took place in Arnhem, The Netherlands on 14-17 September 2018. It was the first time the meeting was held in The Netherlands, and for this reason, excursions were undertaken to five typical Dutch landscapes. Three of the excursions involved newly created nature reserves, located on former agricultural land. The other two were old, protected heathlands. In total, 115 Auchenorrhyncha species, and 6 Psylloidea species were collected. Three species were new for the Netherlands: Macrosteles spinosus (presented in this paper), Kybos abstrusus (monophagous on Populus nigra) and Macrosteles sardus (Epilobium hirsutum). For a number of rare species new occurrences were reported: Kelisia monoceros, Aphrophora major, Stroggylocephalus agrestis, Edwardsiana diversa, E. tersa, Fruticidia bisignata, Ophiola russeola and Psammotettix pallidinervis. Our results show that also in young, newly created nature reserves interesting species can be found.&nbsp

    Transferring biodiversity-ecosystem function research to the management of ‘real-world’ ecosystems

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    Biodiversity-ecosystem functioning (BEF) research grew rapidly following concerns that biodiversity loss would negatively affect ecosystem functions and the ecosystem services they underpin. However, despite evidence that biodiversity strongly affects ecosystem functioning, the influence of BEF research upon policy and the management of ‘real-world’ ecosystems, i.e., semi-natural habitats and agroecosystems, has been limited. Here, we address this issue by classifying BEF research into three clusters based on the degree of human control over species composition and the spatial scale, in terms of grain, of the study, and discussing how the research of each cluster is best suited to inform particular fields of ecosystem management. Research in the first cluster, small-grain highly controlled studies, is best able to provide general insights into mechanisms and to inform the management of species-poor and highly managed systems such as croplands, plantations, and the restoration of heavily degraded ecosystems. Research from the second cluster, small-grain observational studies, and species removal and addition studies, may allow for direct predictions of the impacts of species loss in specific semi-natural ecosystems. Research in the third cluster, large-grain uncontrolled studies, may best inform landscape-scale management and national-scale policy. We discuss barriers to transfer within each cluster and suggest how new research and knowledge exchange mechanisms may overcome these challenges. To meet the potential for BEF research to address global challenges, we recommend transdisciplinary research that goes beyond these current clusters and considers the social-ecological context of the ecosystems in which BEF knowledge is generated. This requires recognizing the social and economic value of biodiversity for ecosystem services at scales, and in units, that matter to land managers and policy makers.</p
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