Os efeitos socioespaciais da expansão canavieira na bacia hidrográfica do rio Ivinhema no Estado de Mato Grosso do Sul

Pós-graduação em Geografia - FCT

O estatuto moral dos animais não-humanos em uma perspectiva sistêmica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Combined pre- and subtemporal transtentorial approach for epidermoid cysts of the cerebellopontine angle

Objective Epidermoid cysts of the cerebellopontine angle (CPA) can be a surgical challenge for the pediatric neurosurgeon. Ideally, total removal must be achieved; however, occasional adhesions of these tumors to vital neurovascular structures and extension far beyond the midline may preclude their total removal. The aims of this article are to present an alternative surgical approach to these lesions and to provide the rationale for this technique. Material and methods A 16-year-old boy was admitted to our pediatric neurosurgery department with a 1-year history of nonspecific headaches. His neurological examination showed right-sided dysmetria and gait ataxia. Magnetic resonance scans showed a space-occupying lesion on the right CPA with low intensity on T-1-weighted images and high intensity on T-2-weighted images. Results Craniotomy for tumor excision via pre- and subtemporal transtentorial approach was performed disclosing a 3.5 x 3 x 2.8-cm(3) well-encapsulated tumor, which was confirmed to be an epidermoid cyst. The postoperative course was uneventful. Conclusions A combined pre- and subtemporal approach utilizes a wide opening of the tentorium and the option of supratentorial retraction of the cerebellum to provide an excellent angle of approach to CPA lesions involving the anterolateral aspect of the brain stem in children.

The last mangroves of Marajo Island - Eastern Amazon: Impact of climate and/or relative sea-level changes

The dynamics, over the last 7500 years, of a mangrove at Marajo Island in northern Brazil were studied by pollen and sedimentary facies analyses using sediment cores. This island, located at the mouth of the Amazon River. is influenced by riverine inflow combined with tidal fluctuations of the equatorial Atlantic Ocean. Herbaceous vegetation intermingled with rainforest dominates the central area of the island, while varzea is the main vegetation type along the littoral. In particular, the modem northeastern coastal zone is covered by a mosaic of dense rainforest, herbaceous vegetation, mangroves, varzea, and restinga. The integration of pollen data and fades descriptions indicates a tidal mud flat colonized by mangroves in the interior of Marajo Island between similar to 7500 cal yr BP and similar to 3200 cal yr BP. During the late Holocene, mangroves retracted to a small area (100-700 m in width) along the northeastern coastal plain. Mangrove expansion during the early and mid Holocene was likely caused by the post-glacial sea-level rise which, combined with tectonic subsidence, led to a rise in tidal water salinity. Salinity must have further increased due to low river discharge resulting from increased aridity during the early and mid Holocene. The shrinking of the area covered by mangrove vegetation during the late Holocene was likely caused by the increase in river discharge during the late Holocene, which has maintained relatively low tidal water salinity in Marajo Island. Tidal water salinity is relatively higher in the northeastern part of the island than in others, due to the southeast-northwest trending current along the littoral. The mixing of marine and riverine freshwater inflows has provided a refuge for mangroves in this area. The increase in flow energy during the last century is related to landward sand migration, which explains the current retraction of mangroves. These changes may indicate an increased exposure to tidal influence driven by the relative sea-level rise, either associated with global fluctuations or tectonic subsidence, and/or by an increase in river water discharge. (C) 2012 Elsevier B.V. All rights reserved.

Multiple Radial Midpupil Lid Distances: A Simple Method for Lid Contour Analysis

Purpose: To describe a new computerized method for the analysis of lid contour based on the measurement of multiple radial midpupil lid distances. Design: Evaluation of diagnostic technology. Participants and Controls: Monocular palpebral fissure images of 35 patients with Graves' upper eyelid retraction and of 30 normal subjects. Methods: Custom software was used to measure the conventional midpupil upper lid distance (MPLD) and 12 oblique MPLDs on each 15 degrees across the temporal (105 degrees, 120 degrees, 135 degrees, 150 degrees, 165 degrees, and 180 degrees) and nasal (75 degrees, 60 degrees, 45 degrees, 30 degrees, 15 degrees, and 0 degrees) sectors of the lid fissure. Main Outcome Measures: Mean, standard deviation, 5th and 95th percentiles of the oblique MPLDs obtained for patients and controls. Temporal/nasal MPLD ratios of the same angles with respect to the midline. Results: The MPLDs increased from the vertical midline in both nasal and temporal sectors of the fissure. In the control group the differences between the mean central MPLD (90 degrees) and those up to 30 degrees in the nasal (75 degrees and 60 degrees) and temporal sectors (105 degrees and 120 degrees) were not significant. For greater eccentricities, all temporal and nasal mean MPLDs increased significantly. When the MPLDs of the same angles were compared between groups, the mean values of the Graves' patients differed from control at all angles (F = 4192; P<0.0001). The greatest temporal/nasal asymmetry occurred 60 degrees from the vertical midline. Conclusions: The measurement of radial MPLD is a simple and effective way to characterize lid contour abnormalities. In patients with Graves' upper eyelid retraction, the method demonstrated that the maximum amplitude of the lateral lid flare sign occurred at 60 degrees from the vertical midline. Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article. Ophthalmology 2012; 119: 625-628 (C) 2012 by the American Academy of Ophthalmology.

Influence of miniscrew dental root proximity on its degree of late stability

Purpose of this study was to evaluate the influence of miniscrew dental root proximity on its late stability degree. 40 miniscrews were inserted between maxillary second premolars and first molars for anterior retraction. Post-surgical radiographs were used to measure the septum width in the insertion site, insertion height, distal and mesial distance from miniscrew to dental root, and the smallest distance between miniscrew and dental root. The miniscrews were divided in two groups according to septum width: ?3 mm (20 miniscrews) and >3 mm (20 miniscrews). The soft tissue in the insertion site, sensitivity during load, plaque around the miniscrew, and evaluation period were also considered. The results showed no significant difference in miniscrew mobility degree and success rate between groups. Miniscrew dental root proximity did not influence the stability and success rate when the distance between the miniscrew and dental root indicated no periodontal ligament invasion. The overall success rate was 90% and no variable was associated with miniscrew failure. Nevertheless, patient sensitivity was frequently associated with some degree of mini-implant mobility. The septum width did not influence the stability and success rate of this anchorage system, but the extreme root proximity did.

The evolutionary implications of hemipenial morphology of rattlesnake Crotalus durissus terrificus (Laurent, 1768) (Serpentes: Viperidae: Crotalinae)

Most amniotes vertebrates have an intromittent organ to deliver semen. The reptile Sphenodon and most birds lost the ancestral penis and developed a cloaca-cloaca mating. Known as hemipenises, the copulatory organ of Squamata shows unique features between the amniotes intromittent organ. They are the only paired intromittent organs across amniotes and are fully inverted and encapsulated in the tail when not in use. The histology and ultrastructure of the hemipenes of Crotalus durissus rattlesnake is described as the evolutionary implications of the main features discussed. The organization of hemipenis of Crotalus durissus terrificus in two concentric corpora cavernosa is similar to other Squamata but differ markedly from the organization of the penis found in crocodilians, testudinata, birds and mammals. Based on the available data, the penis of the ancestral amniotes was made of connective tissue and the incorporation of smooth muscle in the framework of the sinusoids occurred independently in mammals and Crotalus durissus. The propulsor action of the muscle retractor penis basalis was confirmed and therefore the named should be changed to musculus hemipenis propulsor.The retractor penis magnus found in Squamata has no homology to the retractor penis of mammals, although both are responsible for the retraction of the copulatory organ

Structuring of polymer surface by evaporation of sessile microdrops

In this thesis, we investigated the evaporation of sessile microdroplets on different solid substrates. Three major aspects were studied: the influence of surface hydrophilicity and heterogeneity on the evaporation dynamics for an insoluble solid substrate, the influence of external process parameters and intrinsic material properties on microstructuring of soluble polymer substrates and the influence of an increased area to volume ratio in a microfluidic capillary, when evaporation is hindered. In the first part, the evaporation dynamics of pure sessile water drops on smooth self-assembled monolayers (SAMs) of thiols or disulfides on gold on mica was studied. With increasing surface hydrophilicity the drop stayed pinned longer. Thus, the total evaporation time of a given initial drop volume was shorter, since the drop surface, through which the evaporation occurs, stays longer large. Usually, for a single drop the volume decreased linearly with t1.5, t being the evaporation time, for a diffusion-controlled evaporation process. However, when we measured the total evaporation time, ttot, for multiple droplets with different initial volumes, V0, we found a scaling of the form V0 = attotb. The more hydrophilic the substrate was, the more showed the scaling exponent a tendency to an increased value up to 1.6. This can be attributed to an increasing evaporation rate through a thin water layer in the vicinity of the drop. Under the assumption of a constant temperature at the substrate surface a cooling of the droplet and thus a decreased evaporation rate could be excluded as a reason for the different scaling exponent by simulations performed by F. Schönfeld at the IMM, Mainz. In contrast, for a hairy surface, made of dialkyldisulfide SAMs with different chain lengths and a 1:1 mixture of hydrophilic and hydrophobic end groups (hydroxy versus methyl group), the scaling exponent was found to be ~ 1.4. It increased to ~ 1.5 with increasing hydrophilicity. A reason for this observation can only be speculated: in the case of longer hydrophobic alkyl chains the formation of an air layer between substrate and surface might be favorable. Thus, the heat transport to the substrate might be reduced, leading to a stronger cooling and thus decreased evaporation rate. In the second part, the microstructuring of polystyrene surfaces by drops of toluene, a good solvent, was investigated. For this a novel deposition technique was developed, with which the drop can be deposited with a syringe. The polymer substrate is lying on a motorized table, which picks up the pendant drop by an upward motion until a liquid bridge is formed. A consecutive downward motion of the table after a variable delay, i.e. the contact time between drop and polymer, leads to the deposition of the droplet, which can evaporate. The resulting microstructure is investigated in dependence of the processes parameters, i.e. the approach and the retraction speed of the substrate and the delay between them, and in dependence of the intrinsic material properties, i.e. the molar mass and the type of the polymer/solvent system. The principal equivalence with the microstructuring by the ink-jet technique was demonstrated. For a high approach and retraction speed of 9 mm/s and no delay between them, a concave microtopology was observed. In agreement with the literature, this can be explained by a flow of solvent and the dissolved polymer to the rim of the pinned droplet, where polymer is accumulated. This effect is analogue to the well-known formation of ring-like stains after the evaporation of coffee drops (coffee-stain effect). With decreasing retraction speed down to 10 µm/s the resulting surface topology changes from concave to convex. This can be explained with the increasing dissolution of polymer into the solvent drop prior to the evaporation. If the polymer concentration is high enough, gelation occurs instead of a flow to the rim and the shape of the convex droplet is received. With increasing delay time from below 0 ms to 1s the depth of the concave microwells decreases from 4.6 µm to 3.2 µm. However, a convex surface topology could not be obtained, since for longer delay times the polymer sticks to the tip of the syringe. Thus, by changing the delay time a fine-tuning of the concave structure is accomplished, while by changing the retraction speed a principal change of the microtopolgy can be achieved. We attribute this to an additional flow inside the liquid bridge, which enhanced polymer dissolution. Even if the pendant drop is evaporating about 30 µm above the polymer surface without any contact (non-contact mode), concave structures were observed. Rim heights as high as 33 µm could be generated for exposure times of 20 min. The concave structure exclusively lay above the flat polymer surface outside the structure even after drying. This shows that toluene is taken up permanently. The increasing rim height, rh, with increasing exposure time to the solvent vapor obeys a diffusion law of rh = rh0  tn, with n in the range of 0.46 ~ 0.65. This hints at a non-Fickian swelling process. A detailed analysis showed that the rim height of the concave structure is modulated, unlike for the drop deposition. This is due to the local stress relaxation, which was initiated by the increasing toluene concentration in the extruded polymer surface. By altering the intrinsic material parameters i.e. the polymer molar mass and the polymer/solvent combination, several types of microstructures could be formed. With increasing molar mass from 20.9 kDa to 1.44 MDa the resulting microstructure changed from convex, to a structure with a dimple in the center, to concave, to finally an irregular structure. This observation can be explained if one assumes that the microstructuring is dominated by two opposing effects, a decreasing solubility with increasing polymer molar mass, but an increasing surface tension gradient leading to instabilities of Marangoni-type. Thus, a polymer with a low molar mass close or below the entanglement limit is subject to a high dissolution rate, which leads to fast gelation compared to the evaporation rate. This way a coffee-rim like effect is eliminated early and a convex structure results. For high molar masses the low dissolution rate and the low polymer diffusion might lead to increased surface tension gradients and a typical local pile-up of polymer is found. For intermediate polymer masses around 200 kDa, the dissolution and evaporation rate are comparable and the typical concave microtopology is found. This interpretation was supported by a quantitative estimation of the diffusion coefficient and the evaporation rate. For a different polymer/solvent system, polyethylmethacrylate (PEMA)/ethylacetate (EA), exclusively concave structures were found. Following the statements above this can be interpreted with a lower dissolution rate. At low molar masses the concentration of PEMA in EA most likely never reaches the gelation point. Thus, a concave instead of a convex structure occurs. At the end of this section, the optically properties of such microstructures for a potential application as microlenses are studied with laser scanning confocal microscopy. In the third part, the droplet was confined into a glass microcapillary to avoid evaporation. Since here, due to an increased area to volume ratio, the surface properties of the liquid and the solid walls became important, the influence of the surface hydrophilicity of the wall on the interfacial tension between two immiscible liquid slugs was investigated. For this a novel method for measuring the interfacial tension between the two liquids within the capillary was developed. This technique was demonstrated by measuring the interfacial tensions between slugs of pure water and standard solvents. For toluene, n-hexane and chloroform 36.2, 50.9 and 34.2 mN/m were measured at 20°C, which is in a good agreement with data from the literature. For a slug of hexane in contact with a slug of pure water containing ethanol in a concentration range between 0 and 70 (v/v %), a difference of up to 6 mN/m was found, when compared to commercial ring tensiometry. This discrepancy is still under debate.

Eigenschaften von thermoresponsiven Bürstenpolymeren

In dieser Doktorarbeit werden die Eigenschaften von thermoresponsiven Bürstenpolymeren untersucht. Hierbei konnten erstmalig thermische Konformationsübergänge von zylindrischen Bürstenmolekülen auf Oberflächen beobachtet werden. Der Einfluss der Oberfläche auf die Umkehrbarkeit und die Kinetik der Übergänge wurde untersucht. Die dabei erhaltenen Erkenntnisse konnten verwendet werden, um das Verhalten der Polymere auf anderen Oberflächen vorherzusagen. Im zweiten Projekt wurde gezeigt, dass Einzelmolekül-Kraftspektroskopie eine gute Methode für die Untersuchung der mechanischen Eigenschaften von Bürstenpolymeren in guten Lösungsmitteln ist. Mit kleinen Substanzmengen kann die Persistenzlänge der Polymere bestimmt werden. Es ist möglich zu zeigen, dass die Persistenzlänge der Polymerbürsten von ihrer Seitenkettenlänge abhängt. Überraschenderweise funktioniert das Experiment nicht, wenn man die Bürsten aus einem Polymerfilm zieht anstatt ein Einzelmolekülexperiment durchzuführen. In diesem Fall zeigen die Kraft-Abstands-Kurven zu lange Kontur- und Persistenzlängen. Diese Beobachtung ist für lineare Polymere nicht gültig. Im dritten Teil der Doktorarbeit werden Kraft-Abstands-Experimente an einzelnen kollabierten Polymeren untersucht. In schlechten Lösungsmitteln zeigen die Bürsten ein moleküllängenabhängiges Kraft-Plateau, welches theoretisch vorausgesagt wurde und einen Phasenübergang von einem kollabierten zu einem entspannten Zustand der Polymerkette anzeigt. In Fly-Fishing-Experimenten kann man eine Hysterese zwischen den beiden Messkurven beobachten, welche bei mehrfachem Ziehen kleiner wird. Alle Experimente in schlechten Lösungsmitteln wurden mit linearen Polymeren reproduziert, um den Einfluss der Molekülarchitektur von den generellen Eigenschaften von Polymeren in schlechten Lösungsmitteln unterscheiden zu können. Zum Abschluss wird die Abhängigkeit der Polymerentfaltung von der Laderate des Experiments gemessen.

Integrative Musterbildung kranialer Strukturen

Form und Gestalt kraniofazialer Strukturen sind primär beeinflusst durch die inhärente Integration der unterschiedlichsten Funktionssysteme und externer selektiver Einflüsse. Die Variabilität der Schädel-Morphe ist ein Indikator für solche Einflussfaktoren und damit ein idealer Gegenstand für vergleichende Analysen morphogenetischer Formbildung. Zur Ermittlung morphologisch-adaptiver Trends und Muster wurden sowohl Hypothesen zur morphologischen Differenziertheit als auch zu Korrelationen zwischen modularen Schädelkompartimenten (fazial, neurokranial, basikranial) untersucht. Zusätzlich wurden aus Schichtröntgenaufnahmen (CT) virtuelle Modelle rekonstruiert, welche die Interpretation der statistischen Befunde unterstützen sollten. Zur Berechnung der Gestaltunterschiede wurden mittels eines mechanischen Gelenkarm-Messgerätes (MicroScribe-G2) max. 85 ektokraniale Messpunkte (Landmarks) bzw. dreidimensionale Koordinaten an ca. 520 Schädeln von fünf rezenten Gattungen der Überfamilie Hominoidea (Hylobates, Pongo, Gorilla, Pan und Homo) akquiriert. Aus dem Datensatz wurden geometrische Störfaktoren (Größe, Translation, Rotation) mathematisch eliminiert und die verbleibenden Residuale bzw. ‚Gestalt-Variablen‘ diversen multivariat-statistischen Verfahren unterzogen (Faktoren, Cluster-, Regressions- und Korrelationsanalysen sowie statistische Tests). Die angewandten Methoden erhalten die geometrische Information der Untersuchungsobjekte über alle Analyseschritte hinweg und werden unter der Bezeichnung „Geometric Morphometrics (GMM)“ als aktueller Ansatz der Morphometrie zusammengefasst. Für die unterschiedlichen Fragestellungen wurden spezifische Datensätze generiert. Es konnten diverse morphologische Trends und adaptive Muster mit Hilfe der Synthese statistischer Methoden und computer-basierter Rekonstruktionen aus den generierten Datensätzen ermittelt werden. Außerdem war es möglich, präzise zu rekonstruieren, welche kranialen Strukturen innerhalb der Stichprobe miteinander wechselwirken, einzigartige Variabilitäten repräsentieren oder eher homogen gestaltet sind. Die vorliegenden Befunde lassen erkennen, dass Fazial- und Neurokranium am stärksten miteinander korrelieren, während das Basikranium geringe Abhängigkeiten in Bezug auf Gesichts- oder Hirnschädelveränderungen zeigte. Das Basikranium erweist sich zudem bei den nicht-menschlichen Hominoidea und über alle Analysen hinweg als konservative und evolutiv-persistente Struktur mit dem geringsten Veränderungs-Potential. Juvenile Individuen zeigen eine hohe Affinität zueinander und zu Formen mit einem kleinem Gesichts- und großem Hirnschädel. Während das Kranium des rezenten Menschen primär von Enkephalisation und fazialer Retraktion (Orthognathisierung) dominiert ist und somit eine einzigartige Gestalt aufweist, zeigt sich der Kauapparat als maßgeblich formbildendes Kompartiment bei den nicht-menschlichen Formen. Die Verbindung von GMM mit den interaktiven Möglichkeiten computergenerierter Modelle erwies sich als valides Werkzeug zur Erfassung der aufgeworfenen Fragestellungen. Die Interpretation der Befunde ist durch massive Interkorrelationen der untersuchten Strukturen und der statistisch-mathematischen Prozeduren als hoch komplex zu kennzeichnen. Die Studie präsentiert einen innovativen Ansatz der modernen Morphometrie, welcher für zukünftige Untersuchungen im Bereich der kraniofazialen Gestaltanalyse ausgebaut werden könnte. Dabei verspricht die Verknüpfung mit ‚klassischen’ und modernen Zugängen (z. B. Molekularbiologie) gesteigerte Erkenntnismöglichkeiten für künftige morphometrische Fragestellungen.

Rupture forces of split aptamers

Rupture forces of ligand-receptor interactions, such as proteins-proteins, proteins-cells, and cells-tissues, have been successfully measured by atomic force spectroscopy (AFS). For these measurements, the ligands and receptors were chemically modified so that they can be immobilized on the tip and on a substrate, respectively. The ligand interact the receptor when the tip approaches the substrate. This interaction can be studied by measuring rupture force upon retraction. However, this technique is not feasible for measurements involving small molecules, since they form only few H-bonds with their corresponding receptors. Modifying small molecules for immobilization on surfaces may block or change binding sites. Thus, recorded rupture forces might not reflect the full scope of the involved small ligand-receptor interactions.rnIn my thesis, a novel concept that allows measuring the rupture force of small involved ligand-receptor interactions and does not require molecular modification for immobilization was introduced. The rupture force of small ligand-receptor interaction is not directly measured but it can be determined from measurements in the presence and in the absence of the ligand. As a model system, the adenosine mono phosphate (AMP) and the aptamer that binds AMP were selected. The aptamer (receptor) is a single stranded DNA that can partially self-hybridize and form binding pockets for AMP molecules (ligands). The bonds between AMP and aptamer are provided by several H-bonds and pair stacking.rnIn the novel concept, the aptamer was split into two parts (oligo a and oligo b). One part was immobilized on the tip and the other one on the substrate. Approaching the tip to the substrate, oligo a and oligo b partially hybridized and the binding pockets were formed. After adding AMP into the buffer solution, the AMP bound in the pockets and additional H-bonds were formed. Upon retraction of the tip, the rupture force of the AMP-split aptamer complex was measured. In the presence of excess AMP, the rupture force increased by about 10 pN. rnThe dissociation constant of the AMP-split aptamer complex was measured on a single molecular level (~ 4 µM) by varying the AMP concentrations and measuring the rupture force at each concentration. Furthermore, the rupture force was amplified when more pockets were added to the split aptamer. rnIn the absence of AMP, the thermal off-rate was slightly reduced compared to that in the presence of AMP, indicating that the AMP stabilized the aptamer. The rupture forces at different loading rates did not follow the logarithmic fit which was usually used to describe the dependence of rupture forces at different loading rates of oligonucleotides. Two distinguished regimes at low and high loading rates were obtained. The two regimes were explained by a model in which the oligos located at the pockets were stretched at high loading rates. rnThe contribution of a single H-bond formed between the AMP molecule and the split aptamer was measured by reducing the binding groups of the AMP. The rupture forces reduce corresponding to the reduction of the binding groups. The phosphate group played the most important role in the formation of H-bond network between the AMP molecule and the split aptamer. rn

Efficient parallel proximity queries and an application to highly complex motion planning problems with many narrow passages

In vielen Bereichen der industriellen Fertigung, wie zum Beispiel in der Automobilindustrie, wer- den digitale Versuchsmodelle (sog. digital mock-ups) eingesetzt, um die Entwicklung komplexer Maschinen m ̈oglichst gut durch Computersysteme unterstu ̈tzen zu k ̈onnen. Hierbei spielen Be- wegungsplanungsalgorithmen eine wichtige Rolle, um zu gew ̈ahrleisten, dass diese digitalen Pro- totypen auch kollisionsfrei zusammengesetzt werden k ̈onnen. In den letzten Jahrzehnten haben sich hier sampling-basierte Verfahren besonders bew ̈ahrt. Diese erzeugen eine große Anzahl von zuf ̈alligen Lagen fu ̈r das ein-/auszubauende Objekt und verwenden einen Kollisionserken- nungsmechanismus, um die einzelnen Lagen auf Gu ̈ltigkeit zu u ̈berpru ̈fen. Daher spielt die Kollisionserkennung eine wesentliche Rolle beim Design effizienter Bewegungsplanungsalgorith- men. Eine Schwierigkeit fu ̈r diese Klasse von Planern stellen sogenannte “narrow passages” dar, schmale Passagen also, die immer dort auftreten, wo die Bewegungsfreiheit der zu planenden Objekte stark eingeschr ̈ankt ist. An solchen Stellen kann es schwierig sein, eine ausreichende Anzahl von kollisionsfreien Samples zu finden. Es ist dann m ̈oglicherweise n ̈otig, ausgeklu ̈geltere Techniken einzusetzen, um eine gute Performance der Algorithmen zu erreichen.rnDie vorliegende Arbeit gliedert sich in zwei Teile: Im ersten Teil untersuchen wir parallele Kollisionserkennungsalgorithmen. Da wir auf eine Anwendung bei sampling-basierten Bewe- gungsplanern abzielen, w ̈ahlen wir hier eine Problemstellung, bei der wir stets die selben zwei Objekte, aber in einer großen Anzahl von unterschiedlichen Lagen auf Kollision testen. Wir im- plementieren und vergleichen verschiedene Verfahren, die auf Hu ̈llk ̈operhierarchien (BVHs) und hierarchische Grids als Beschleunigungsstrukturen zuru ̈ckgreifen. Alle beschriebenen Verfahren wurden auf mehreren CPU-Kernen parallelisiert. Daru ̈ber hinaus vergleichen wir verschiedene CUDA Kernels zur Durchfu ̈hrung BVH-basierter Kollisionstests auf der GPU. Neben einer un- terschiedlichen Verteilung der Arbeit auf die parallelen GPU Threads untersuchen wir hier die Auswirkung verschiedener Speicherzugriffsmuster auf die Performance der resultierenden Algo- rithmen. Weiter stellen wir eine Reihe von approximativen Kollisionstests vor, die auf den beschriebenen Verfahren basieren. Wenn eine geringere Genauigkeit der Tests tolerierbar ist, kann so eine weitere Verbesserung der Performance erzielt werden.rnIm zweiten Teil der Arbeit beschreiben wir einen von uns entworfenen parallelen, sampling- basierten Bewegungsplaner zur Behandlung hochkomplexer Probleme mit mehreren “narrow passages”. Das Verfahren arbeitet in zwei Phasen. Die grundlegende Idee ist hierbei, in der er- sten Planungsphase konzeptionell kleinere Fehler zuzulassen, um die Planungseffizienz zu erh ̈ohen und den resultierenden Pfad dann in einer zweiten Phase zu reparieren. Der hierzu in Phase I eingesetzte Planer basiert auf sogenannten Expansive Space Trees. Zus ̈atzlich haben wir den Planer mit einer Freidru ̈ckoperation ausgestattet, die es erlaubt, kleinere Kollisionen aufzul ̈osen und so die Effizienz in Bereichen mit eingeschr ̈ankter Bewegungsfreiheit zu erh ̈ohen. Optional erlaubt unsere Implementierung den Einsatz von approximativen Kollisionstests. Dies setzt die Genauigkeit der ersten Planungsphase weiter herab, fu ̈hrt aber auch zu einer weiteren Perfor- mancesteigerung. Die aus Phase I resultierenden Bewegungspfade sind dann unter Umst ̈anden nicht komplett kollisionsfrei. Um diese Pfade zu reparieren, haben wir einen neuartigen Pla- nungsalgorithmus entworfen, der lokal beschr ̈ankt auf eine kleine Umgebung um den bestehenden Pfad einen neuen, kollisionsfreien Bewegungspfad plant.rnWir haben den beschriebenen Algorithmus mit einer Klasse von neuen, schwierigen Metall- Puzzlen getestet, die zum Teil mehrere “narrow passages” aufweisen. Unseres Wissens nach ist eine Sammlung vergleichbar komplexer Benchmarks nicht ̈offentlich zug ̈anglich und wir fan- den auch keine Beschreibung von vergleichbar komplexen Benchmarks in der Motion-Planning Literatur.

WASP plays a novel role in regulating platelet responses dependent on alphaIIbbeta3 integrin outside-in signalling

The most consistent feature of Wiskott Aldrich syndrome (WAS) is profound thrombocytopenia with small platelets. The responsible gene encodes WAS protein (WASP), which functions in leucocytes as an actin filament nucleating agent -yet- actin filament nucleation proceeds normally in patient platelets regarding shape change, filopodia and lamellipodia generation. Because WASP localizes in the platelet membrane skeleton and is mobilized by alphaIIbbeta3 integrin outside-in signalling, we questioned whether its function might be linked to integrin. Agonist-induced alphaIIbbeta3 activation (PAC-1 binding) was normal for patient platelets, indicating normal integrin inside-out signalling. Inside-out signalling (fibrinogen, JON/A binding) was also normal for wasp-deficient murine platelets. However, adherence/spreading on immobilized fibrinogen was decreased for patient platelets and wasp-deficient murine platelets, indicating decreased integrin outside-in responses. Another integrin outside-in dependent response, fibrin clot retraction, involving contraction of the post-aggregation actin cytoskeleton, was also decreased for patient platelets and wasp-deficient murine platelets. Rebleeding from tail cuts was more frequent for wasp-deficient mice, suggesting decreased stabilisation of the primary platelet plug. In contrast, phosphatidylserine exposure, a pro-coagulant response, was enhanced for WASP-deficient patient and murine platelets. The collective results reveal a novel function for WASP in regulating pro-aggregatory and pro-coagulant responses downstream of integrin outside-in signalling.

The Pararectus approach for anterior intrapelvic management of acetabular fractures: an anatomical study and clinical evaluation

A new anterior intrapelvic approach for the surgical management of displaced acetabular fractures involving predominantly the anterior column and the quadrilateral plate is described. In order to establish five 'windows' for instrumentation, the extraperitoneal space is entered along the lateral border of the rectus abdominis muscle. This is the so-called 'Pararectus' approach. The feasibility of safe dissection and optimal instrumentation of the pelvis was assessed in five cadavers (ten hemipelves) before implementation in a series of 20 patients with a mean age of 59 years (17 to 90), of whom 17 were male. The clinical evaluation was undertaken between December 2009 and December 2010. The quality of reduction was assessed with post-operative CT scans and the occurrence of intra-operative complications was noted. In cadavers, sufficient extraperitoneal access and safe instrumentation of the pelvis were accomplished. In the patients, there was a statistically significant improvement in the reduction of the fracture (pre- versus post-operative: mean step-off 3.3 mm (sd 2.6) vs 0.1 mm (sd 0.3), p < 0.001; and mean gap 11.5 mm (sd 6.5) vs 0.8 mm (sd 1.3), p < 0.001). Lesions to the peritoneum were noted in two patients and minor vascular damage was noted in a further two patients. Multi-directional screw placement and various plate configurations were feasible in cadavers without significant retraction of soft tissues. In the treatment of acetabular fractures predominantly involving the anterior column and the quadrilateral plate, the Pararectus approach allowed anatomical restoration with minimal morbidity related to the surgical access.

Rapid cytopathic effects of Clostridium perfringens beta-toxin on porcine endothelial cells

Clostridium perfringens type C isolates cause fatal, segmental necro-hemorrhagic enteritis in animals and humans. Typically, acute intestinal lesions result from extensive mucosal necrosis and hemorrhage in the proximal jejunum. These lesions are frequently accompanied by microvascular thrombosis in affected intestinal segments. In previous studies we demonstrated that there is endothelial localization of C. perfringens type C beta-toxin (CPB) in acute lesions of necrotizing enteritis. This led us to hypothesize that CPB contributes to vascular necrosis by directly damaging endothelial cells. By performing additional immunohistochemical studies using spontaneously diseased piglets, we confirmed that CPB binds to the endothelial lining of vessels showing early signs of thrombosis. To investigate whether CPB can disrupt the endothelium, we exposed primary porcine aortic endothelial cells to C. perfringens type C culture supernatants and recombinant CPB. Both treatments rapidly induced disruption of the actin cytoskeleton, cell border retraction, and cell shrinkage, leading to destruction of the endothelial monolayer in vitro. These effects were followed by cell death. Cytopathic and cytotoxic effects were inhibited by neutralization of CPB. Taken together, our results suggest that CPB-induced disruption of endothelial cells may contribute to the pathogenesis of C. perfringens type C enteritis.