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Search Results: 1 - 10 of 2103 matches for " Sven Eicker "
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The Impact of Experimental Preconditioning Using Vascular Endothelial Growth Factor in Stroke and Subarachnoid Hemorrhage
Sven Oliver Eicker,Moritz Hoppe,Nima Etminan,Stephan Macht
Stroke Research and Treatment , 2013, DOI: 10.1155/2013/948783
Abstract:
The Impact of Experimental Preconditioning Using Vascular Endothelial Growth Factor in Stroke and Subarachnoid Hemorrhage
Sven Oliver Eicker,Moritz Hoppe,Nima Etminan,Stephan Macht,Jason Perrin,Hans-Jakob Steiger,Daniel H?nggi
Stroke Research and Treatment , 2013, DOI: 10.1155/2013/948783
Abstract: Vascular endothelial growth factor (VEGF) stimulating angiogenesis was shown to be a potential novel therapeutic approach for the treatment of ischemic vascular diseases. The goal of the present study was to examine whether transfection of VEGF before occurrence of major stroke (part I) and cerebral vasospasm after experimental subarachnoid hemorrhage (SAH; part II) develops neuroprotective qualities. A total of 25 (part I) and 26 (part II) brains were analyzed, respectively. In part one, a significant reduction of infarct volume in the VEGF-treated stroke animals (43% reduction, ) could be detected. In part two, significant vasospasm was induced in all hemorrhage groups . Analyzing microperfusion, a significant higher amount of perfused vessels could be detected , whereas no significant effect could be detected towards macroperfusion. Histologically, no infarctions were observed in the VEGF-treated SAH group and the sham-operated group. Minor infarction in terms of vasospasm-induced small lesions could be detected in the control vector transduced group and saline-treated group . The present study demonstrates the preconditioning impact of systemic intramuscular VEGF injection in animals after major stroke and induced severe vasospasm after SAH. 1. Introduction Cerebral vasospasm and delayed cerebral ischemia contribute the major part of secondary morbidity and mortality after severe subarachnoid hemorrhage (SAH) [1–5]. Despite the current treatment strategies, the rate of related permanent disability is estimated at 10% to 20% [6–9]. Vascular endothelial growth factor (VEGF) is involved in neurogenesis, inhibition of apoptosis, learning, and memory [10]. It can directly promote neuroprotection, but first of all VEGF is the main factor responsible for angiogenesis whereby an indirect neuroprotection is discussed. VEGF expression is increased during cerebral ischemia in humans and animals [11]. However, endogenous VEGF seems to be insufficient to protect the brain from ischemic injury completely. Interestingly, it could be shown that exogenous administrated VEGF induces angiogenic changes that result in a reduction of cerebral ischemic injury [12, 13]. For this reason VEGF was adopted as a potential novel therapeutic approach for the treatment of ischemic vascular disease, particularly in ischemic stroke [14–18]. The aim of the present experimental study was to examine the effect of systemic overexpression of VEGF prior to stroke and SAH with regard to cerebral infarction, vasospasm, and perfusion. 2. Material and Methods This study was carried out in
Local Delivery of Nimodipine by Prolonged-Release Microparticles—Feasibility, Effectiveness and Dose-Finding in Experimental Subarachnoid Hemorrhage
Daniel H?nggi, Jason Perrin, Sven Eicker, Kerim Beseoglu, Nima Etminan, Marcel Alexander Kamp, Hi-Jae Heiroth, Nadia Bege, Stephan Macht, Katrin Frauenknecht, Clemens Sommer, Thomas Kissel, Hans-Jakob Steiger
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042597
Abstract: Background and Purpose To investigate the effect of locally applied nimodipine prolonged-release microparticles on angiographic vasospasm and secondary brain injury after experimental subarachnoid hemorrhage (SAH). Methods 70 male Wistar rats were categorized into three groups: 1) sham operated animals (control), 2) animals with SAH only (control) and the 3) treatment group. SAH was induced using the double hemorrhage model. The treatment group received different concentrations (20%, 30% or 40%) of nimodipine microparticles. Angiographic vasospasm was assessed 5 days later using digital subtraction angiography (DSA). Histological analysis of frozen sections was performed using H&E-staining as well as Iba1 and MAP2 immunohistochemistry. Results DSA images were sufficient for assessment in 42 animals. Severe angiographic vasospasm was present in group 2 (SAH only), as compared to the sham operated group (p<0.001). Only animals within group 3 and the highest nimodipine microparticles concentration (40%) as well as group 1 (sham) demonstrated the largest intracranial artery diameters. Variation in vessel calibers, however, did not result in differences in Iba-1 or MAP2 expression, i.e. in histological findings for secondary brain injury. Conclusions Local delivery of high-dose nimodipine prolonged-release microparticles at high concentration resulted in significant reduction in angiographic vasospasm after experimental SAH and with no histological signs for matrix toxicity.
Lattice Enthalpy Drives Hubbard U to Zero  [PDF]
Sven Larsson
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.46A007
Abstract:

In the equation U = IA for the Mott energy, the electron-hole interaction of the successor state is missing. Adding the attractive term, the energy for disproportionation (Hubbard U), may adopt any sign. The missing term is related to the Born effect, the Madelung correction and the Lattice Enthalpy.

Cyclic Vitalism: The Dialectics of Life and Death in German Poetry around 1900*  [PDF]
Sven Halse
Advances in Literary Study (ALS) , 2014, DOI: 10.4236/als.2014.21004
Abstract:

Over the past decade, Scandinavian and German scholars have been active in the redefinition of the terms “Vitalism” and “Vitalist” as descriptive categories for analytical purposes in the fields of literary and cultural history. In this context,“Vitalism”has primarily been used to describe an enthusiastic worshipping of life, one that holds youth, health, strength and beauty as its primary attributes, which was prevalent in all aspects of cultural life around 1900. But even the post war founders of the Vitalist re-conceptualisation of this era, Wolfdietrich Rasch and Gunter Martens, warned of taking such a unilateral view ofwhat constituted a Vitalist concept of life. It could lead to a misunderstanding of Vitalist way of thinking, Rasch said, if the focus wasonly set upon the enthusiastic surplus, the worshipping of youth and health. To Vitalists, life is more than that. It is a totality that also encompasses notions of destruction, decay and death. “All life symbols in literature around 1900 are at the same time symbols of death” (Rasch, 1967:24).Through the analyses of three poems, this article aims to show concrete examples of how cyclic Vitalist thinking is embedded in poetry of the era. The analyses include a further sub-categorisation to capture the different types of Life Force dealt with in the texts. By way of an introduction, Vitalism is discussed within the context of the scientific and social developments of the 19th Century.

Minimising Excessive Energy Consumption in Schools While Maintaining Optimal Air Quality  [PDF]
Sven Hallin
Open Journal of Optimization (OJOp) , 2017, DOI: 10.4236/ojop.2017.64010
Abstract: This paper presents an assessment of how to minimise excessive energy consumption in a case study school classroom while maintaining optimal indoor air quality. Using mixed method research with qualitative interview data supporting quantitative key data measurements, essential primary data was extracted from temperature and carbon dioxide monitoring equipment in the classroom. This was then used, along with other ancillary data, to develop an IES computer model of the classroom as a “base case” reflecting existing energy consumption, temperatures and CO2 levels. Eight different interventions were then developed and modelled which reflected improved energy supply and a variety of ventilation strategies. The results show that adequate control and design of energy supply systems is critical to minimising excessive energy consumption, and that adequate internal air quality is achievable through a variety of low cost strategies.
Generalized Option Betas  [PDF]
Sven Husmann, Neda Todorova
Journal of Mathematical Finance (JMF) , 2013, DOI: 10.4236/jmf.2013.33035
Abstract:

This paper extends the option betas presented by Cox and Rubinstein (1985) and Branger and Schlag (2007). In particular, we show how the beta of the underlying asset affects both an option’s covariance beta and its asset pricing beta. In contrast to Branger and Schlag (2007), the generalized option betas coincide if the options are evaluated according to the CAPM option pricing model of Husmann and Todorova (2011). The option betas are presented in terms of Black-Scholes option prices and are therefore easy to use in practice.

Wind-Driven Dynamics of Beach-Cast Wrack in a Tide-Free System  [PDF]
Sven Hammann, Martin Zimmer
Open Journal of Marine Science (OJMS) , 2014, DOI: 10.4236/ojms.2014.42009
Abstract:

Whereas wrack dynamics on tidally influenced beaches have been studied to some detail, essentially nothing is known about how drift lines in tide-free coastal systems vary in space and time. We provide evidence for high spatial and temporal dynamics of beach-cast wrack on a sand beach in the Western Baltic Sea. Over the course of one year, the amount of weekly deposited macrophyte wrack fluctuated from zero to 3000 g·m-1 shoreline. Wrack mostly accumulated just above the waterline. Part of the beach-cast wrack is frequently re-suspended into coastal water upon extreme high water level events, or wrack patches are translocated landwards by wind-driven changes in water level or along the shoreline by winds. Consequently, the deposited wrack does accumulate, but a steady-state of ca 400 g·m-1 builds up within 2 - 3 weeks. Eelgrass wrack buried in sand decomposed almost twice as fast as on top of the sand or re-suspended in water. Fragmentation of leaves promoted decomposition only when wrack remained on the sand surface. The spatial and temporal distribution of this valuable source of organic matter is unpredictable and depends on wind and wind-driven waves.

Influence of Random Pinning on the Crystallization Process in Suspensions of Hard Spheres  [PDF]
Sven Dorosz, Tanja Schilling
Journal of Crystallization Process and Technology (JCPT) , 2014, DOI: 10.4236/jcpt.2014.42012
Abstract: We discuss crystal formation in supersaturated suspensions of monodisperse hard spheres with a concentration of hard spheres randomly pinned in space and time. The pinning procedure introduces an external length scale and an external time scale that restrict the accessible number of configureurations and ultimately the number of pathways leading to crystallization. We observe a significant drop in the nucleation rate density at a characteristic pinning concentration that can be directly related to the structure of the critical nucleus and the dynamics of its formation in the unpinned system.
Nytt fra NOR - News
Sven Sven Skjenneberg
Rangifer , 1982,
Abstract:
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