37 research outputs found
The influence of hollow cylinder on the blood supply of the lumbar vertebra
No full textDie adäquate Therapie der Osteoporose und ihrer Komplikationen ist eine der großen Herausforderungen für die heutige Medizin. Auf der Suche nach Verbesserungen aktueller operativer Stabilisierungsmethoden osteoporotischer Wirbelfrakturen hat unsere Arbeitsgruppe das Hollowfix-Implantat entwickelt. Auf Grundlage des Zusammenhangs, dass eine optimale Blutversorgung eine wichtige Grundvoraussetzung für eine optimale Frakturheilung ist, wurden Manipulation und Veränderung der Wirbelperfusion besondere Aufmerksamkeit gewidmet.
In der vorliegenden Arbeit sollte der individuelle Einfluss des Betrachters, der bei bisherigen Methoden der Flächenbestimmung vorliegt, minimiert werden. Anschließend sollte eine Analyse der initialen Durchblutungssituation des Wirbelkörpers unmittelbar nach Implantatinsertion und nach einer Woche durchgeführt werden, um einerseits das Implantatdesign und andererseits die fragliche Regeneration zu bewerten.
Mit dem Schaf als Tiermodell und mittels Disulfinblau gefärbten Schnittbildern wurde ein Verfahren unter Adobe® Photoshop® erstellt, das unsere Anforderungen erfüllt. Es zeigt sich, dass ein perforiertes gegenüber einem soliden Zylinderdesign initial den Vorteil einer Restdurchblutung ergibt. Daten der Perfusion des innerhalb des Hohlzylinders befindlichen Knochengewebes lassen ab einer Bohrtiefe von 9,1 mm auf eine retrograde Durchblutung schließen, die durch die Hohlzylinder kaum beeinträchtigt wird. In geringeren Schnitttiefen kommt es nach einer Woche zu einer deutlichen Regeneration der Perfusion, die prozentuale Fläche des durchbluteten Gewebes erhöht sich um 41 - 64 Prozentpunkte.
Durch eine Analyse der Lokalisation der peripher um das Implantat gestörten Durchblutung konnte die Sensibilität in Grund- und Deckplattennähe aufgezeigt werden.Osteoporosis is a big challenge for today's medicine. In search of a better operative therapy our group developed a new hollow cylinder for the osteosynthesis of the fractured lumbar vertebra. Because an adaequat ostheosynthesis requires an optimal blood supply of the bone, we took a close look the change of the blood perfusion.
We used a new method for the determination of the vascularized areas of the bone and minimized the observers influence. With that method we analyzed the initial situation of blood supply after osteosynthesis and after one week and compared different styles of hollow cylinders. Also we tried to localize the damage of blood supply inside the lumbar vertebra. We used a sheep as an animal model and disulphin blue for the intra vitam staining.
We could see no negativ effect of a perforated hollow cylinder and saw almost a significant rise of the blood perfusion inside the cylinder after one week. Also we saw an characteristic correlation between blood perfusion inside the implant and the cutting depth. In addition to that we located most of the damage near to the endplate
Scheduling the Spark Framework under the Mesos Resource Manager
No full textUsing clusters of servers and datacenters to process large numbers of data- and computation-intensive jobs is becoming mainstream. The need for large clusters is driven by the fact that many workloads are growing at a faster rate than the advances in single computer performance. To manage processing in a cluster of multiple computers, several frameworks have appeared over the years. These frameworks supply the user with convenient computation constructs and abstract from the low-level implementations to relieve the burden of inter-process communication and task placement in a cluster. However, these frameworks often assume total control over a static partition of the cluster, leading to under-utilization in times when one framework is over-committed with work, whereas another framework is idling. To overcome this under-utilization, and multiplex frameworks in clusters, cluster schedulers have been proposed, which sit on top of the hardware resources and schedule hardware resource leases to frameworks. It is not well described how these systems differ from each other. Furthermore, how to achieve \emph{performance balance} between frameworks, such that multiple frameworks achieve similar performance metrics when running time-varying workloads is relatively unexplored. We define a taxonomy which describes the combination of cluster schedulers and frameworks, called Two-Level schedulers in general. We characterize the multiple state-of-the-art cluster schedulers that are described in the literature or are used in practice. We distinguish multiple aspects which define the cluster schedulers. These aspects can dictate how frameworks interface with the cluster scheduler and can also influence framework performance. We aim to achieve performance balance for multiple \gls{spark} frameworks running under the \gls{mesos} cluster scheduler. First, we evaluate the performance of a single framework running single interactive data analytics queries. We find multiple configuration parameters which influence the performance for interactive queries. However, we conclude that using \gls{sparkmesos} for interactive queries results in either inefficient use of resources, or does not allow us to multiplex resources over multiple frameworks. We continue with achieving performance balance for multiple frameworks for non-interactive queries. We first establish a baseline performance balance, which we attain by using knowledge of the possibly different workload intensities run by the frameworks in a real cluster. Afterwards, we achieve similar performance balance, compared to the baseline, for up to three frameworks without knowing the workload intensity a priori. This is achieved by using a feedback loop controller, which updates resource share sizes allocated to frameworks dynamically, based on the online performance metrics of the frameworks.Electrical Engineering, Mathematics and Computer ScienceSoftware Technology - Distributed SystemsComputer Science, Software TechnologyIN500
Kina•ldá Navaho Girls' Puberty Rite
No full textThe acquisition of adult status receives ritualistic attention in most societies. As van Gennep has demonstrated, these rites of social puberty which may or may not be associated with physiological changes. In either case, they are “rites of passage” which terminate the initiate’s membership in one group, namely that of the adolescents, and incorporate him into another, that of the adults. Although such rites of passage may be held for both males and females, at this time, the author is concerned with female imitation alone. Why do some societies have female initiation rites while others do not? The author examines two related, but independent, approaches. Methodology includes examining the Kina•ldá
28 nm CMOS Array of Strips for Pedestrian Detection
No full textDue to technology trends such as autonomous driving, the need for robust safety in the automotive industry increases. The safety comes from sensors that are able to image the environment and systems that use this information to avoid incidents and retain maximum safety. Detection of pedestrian has high importance since a missed detection can be lethal. Current solutions for pedestrian detection are based on infrared and optical cameras. With these solutions it can be challenging to detect pedestrians under conditions such as cold/foggy conditions, especially during nighttime. In this scenario through clothes penetration of infrared radiation is poor. Instead, terahertz radiation penetrates better through clothes, making terahertz imagers a viable solution to increase safety in theframework of autonomous driving.The focus on automotive sensors requires that the solution needs to be low-cost, low power and compact. Traditional passive terahertz detectors are based on cryogenically cooling or active illumination of the target to maximize the sensitivity, since this is not applicable in automotive designs we design an array that can be combined with direct detectors to increases the sensitivity by maximizing the effective bandwidth. The sensor needs to have sufficient resolution to detect the pedestrians at distances up to 10 meters combined with sufficient sensitivity to also perform in weather conditions such as fog
Performance of reliability methods in geomechanical applications
No full textReliability-based design is an approach currently gaining more popularity for geotechnical engineering. Neverthless, its implementation poses several challenges, one being the additional time (usually significant) in order to perform it. An important portion of this additional time comes from the need to perform many scenarios to compute the probability of failure: a Monte Carlo analysis (the most widespread procedure) can easily take more than tens of thousands of realisations to converge. Moreover, there is a tendency to use complex models in practice (e.g. finite element analysis), producing more often prohibitive computation time. This thesis attempts to find alternative reliability methods to Monte Carlo capable of reducing the computation time for geomechanical problems in the oil and gas industry. The methodology is to evaluate several different methods (named workflows) for specific examples. The terms of the evaluations are in accuracy (defined as the closeness to the exact result obtained by a Monte Carlo analysis) and efficiency (measured in the number of geomechanical model realisations). Among the proposed workflows (i.e. methods), there is one which is capable of computing accurately and efficiently the probability of failure for all the analysis made, and others which have a potential to do so, if some improvements are performed. The worklow currently capable is First-Order Reliability Method (FORM), requiring around 30 to 100 realisations for cases with 6 and 11 random variables, respectively. The workflows with potential to be accurate and efficient are FORM and Monte Carlo applied on a response surface that updates (instead of directly using the actual complex model), which required between 10 to 30 realisations. Both represent a strong reduction versus a Monte Carlo analysis, which at took approximately 20,000 to 60,000 realisations in this study. However, for the latter workflows the accuracy on the probability of failure depends on the degree of non-linearity of the response and the target probability of failure. When the non-linearity is high and/or the target low, the updates of the response surface stops before it can accurately represent the actual response in the most probable failure region, subsequently obtaining low accuracies on the probability of failure. A connection between the updates and the prediction of the actual response surface is thought to be able to improve this workflows in order to achieve good accuracies for all the examples analysed in the study. Therefore, it is feasible with the methods proposed to compute accurately and efficiently the reliability in geotechnical engineering, but this conclusion is restricted to for the specific examples evaluated in this study. If a new type of problem is desired to be addressed, it is recommended to validate them first (by comparing their results to Monte Carlo analysis), before using them confidently in practice.Geo-engineeringGeoscience & EngineeringCivil Engineering and Geoscience
Die konservative und operative Therapie der unspezifischen Spondylodiszitis
No full textZusammenfassungDie pyogene Spondylodiszitis entsteht meist endogen durch eine Bakteriämie, aber auch exogene Ursachen wie etwa wirbelsäulennahe Infiltrationen können sie hervorrufen. Es besteht eine zunehmende Inzidenz der Erkrankung, die noch immer mit einer signifikanten Mortalität der in vielen Fällen immunsupprimierten und hochbetagten Patienten einhergeht. Eine frühzeitige Diagnosestellung durch Bildgebung und Erregerisolierung ist entscheidend für ein gutes Behandlungsergebnis. Die überwiegende Zahl der Patienten kann konservativ behandelt werden, wichtig sind ein frühzeitiger Beginn der antibiotischen Therapie sowie eine adäquate Ruhigstellung. Operative Therapieziele sind neben der Dekompression und Infektsanierung die Stabilisation und Deformitätenkorrektur. Es kommen rein dorsale offene Verfahren, ggf. mit Ausräumung der Bandscheibe und TLIF, sowie minimalinvasive Stabilisierungen zur Anwendung. Bei ausgeprägten ventralen Destruktionen, Fehlstellungen und Abszedierungen muss durch einen separaten ventralen Zugang debridiert und stabilisiert werden. In der überwiegenden Zahl der Fälle können gute Behandlungsergebnisse erreicht werden, in Einzelfällen bestehen jedoch große therapeutische Herausforderungen. Individuelle Therapieentscheidungen sind notwendig, da einerseits die Literatur keine eindeutigen Behandlungsleitlinien vorgibt und es sich andererseits um teils hochbetagte und multimorbide Patienten handelt.</jats:p
Productie van alkylpolyglycosiden uit zetmeel
No full textDocument(en) uit de collectie Chemische Procestechnologie.DelftChemTechApplied Science
Episodes from the Continuous Search for Solutions against Downy Mildew Diseases
No full textDiscovery background, lead optimization pathways, synthesis and structure–activity relationships of three different research projects searching for new active ingredients against downy mildew diseases are reported. These case studies, on which the author worked in three different
decades in the research departments of Syngenta Crop Protection AG and its legacy company Novartis Crop Protection AG deal with inhibitors of cellulose synthase, tubulin polymerization and oxysterol-binding protein. Rarely used reactions, which have been applied within these projects, such
as Seebach\u27s variation of the Passerini reaction, the Bogert quinazoline synthesis and the carbonyldiimidazole-mediated Lossen rearrangement give proof of the significance of synthetic organic chemistry for modern crop protection
