Nichtlineare Registrierung von Diffusions-Tensor-Bildern

Viele Wissenschafts- und Ingenieursdisziplinen, wie Mikroskopie, medizinische Diagnostik, Astronomie oder Maschinenbau, nutzen die Methoden und Techniken der Bildverarbeitung, um bestimmte Objekte darzustellen, zu zählen, zu vermessen und Ähnliches. Eine häufig genutzte Technik in der digitalen Bildverarbeitung ist die Bildregistrierung. Darunter versteht man Methoden, die es ermöglichen, zwei oder mehrere Bilder derselben Szene, oder zumindest ähnlicher Szenen, bestmöglich in Übereinstimmung miteinander zu bringen. Mit anderen Worten, beim Registrierungsproblem geht es darum, eine Übereinstimmung zwischen den Punkten zweier oder mehrerer Bilder herzustellen

Methylierte Arsen- und Antimonspezies in Böden und Sedimenten

Die Konzentrationen methylierter As- und Sb-Verbindungen (MAs- und MSb-Verbingungen) in Böden und Sedimenten (93 Proben) liegen im Bereich von 10 - 10 μg/kg. Die dominierenden Spezies sind Monomethylarsen (MMAs), Dimethylarsen (DMAs) und Monomethylantimon (MMSb) sowie Dimethylantimon) DMSb. Die höchsten Konzentrationen treten in Böden und Sedimenten auf, welche entweder eine deutliche Förderung der Bodenbiologie erfahren (z.B. Äcker) oder eine starke Belastung mit anorganischem As und Sb zeigen (z.B. Spülteich der Bleierzgewinnung). Standorte, welche keiner direkten anthropogenen Kontamination mit As und Sb unterliegen traten Konzentrationen < 20 μg/kg auf. Für das Vorkommen von MAs und MSb im Feststoffanteil von Böden und Sedimenten, als auch in echter Lösung des Sedimentporenwassers (Mikrofiltration), liegt ein statistisch signifikanter Zusammenhang vor. Im Gegensatz zu den MAs-Spezies erfahren die MSb-Spezies im Frühjahr in einem Ackerboden eine Speziesmuster Verschiebung hin zum DMSb. Der Gehalt an MSb-Spezies in sedimentbürtigen Schwebstoffen der Ruhr steht in einer direkten Beziehung zum Winterhochwasser und ist am deutlichsten durch die Verlagerung von Sediment- und Bodenmaterial aus dem Einzugsgebiet der Ruhr (Niederschläge und Schneeschmelze) beeinflusst. MAs Spezies in den schwebstoffbürtigen Sedimenten zeigen die stärkste Beeinflussung durch die Frühjahrsalgenblüte. Dies ist ein Beleg der besseren Metabolisierung von As im Vergleich zu Sb durch Süßwasseralgen. In verschiedenen Inkubationsexperimenten, unter anderem mit dem Sediment Or Fauna Incubation Experiment (SOFIE®, EU-patent 1018200 / 02077121.8), wird das gesamte Muster an methylierten As und Sb Spezies (mono-, di-, trimethyl-,) im 0,1 μm filtrierten Porenwasser belegt (im Bereich von 1 μg/l). Dies ist der erste Nachweis dieser Spezies in echter Lösung des Porenwassers und unterstreicht die Umweltrelevanz des Methylierungsprozesses bei der Verlagerung der Metalloide. Die Methylierung erfolgt für beide Elemente sowohl aerob, als auch anaerob. Im Gegensatz zu den Speziesmustern im Feststoffanteil, sind die Muster in den Porenwässern der Inkubationsversuche eindeutig durch das Auftreten zweifach methylierter Spezies dominiert. Neben der signifikanten Korrelation zwischen MAs und MSb im Porenwasser und im Feststoffanteil, wird ein statistischer Zusammenhang zwischen der Sb Konzentration der einen Probenentnahme und der MSb Konzentration der darauf folgenden Probenentnahme belegt. Dies legt den zeitlichen Rahmen zwischen der höchsten Verlagerbarkeit/Verfügbarkeit der anorganischen Spezies bis zu der Verlagerung der methylierten Spezies auf 10 - 20 Tage fest. Weitere Zusammenhänge zwischen dem Auftreten von Sb-Spezies im Porenwasser und Begleitparametern waren nicht zu belegen. Für As wird ein Zusammenhang zwischen dem As(III) Gehalt und dem Gehalt an MMAs dokumentiert. Das parallele Auftreten von As(III) und MMAs in echter Lösung des Porenwassers zeigt, dass ein zählbarerer Anteil der beiden Spezies nicht einer weiteren Umwandlung durch eine Methylierung unterworfen ist, sondern von den Organismen unter nativen Bedingungen an die Umgebung abgegeben wird. Auch hier spricht die gute Übereinstimmung mit den Zeitpunkten der höchsten biologischen Aktivität gegen eine maßgebliche anorganische Umwandlung der Spezies. Für eine Beurteilung der Umweltrelevanz der im Screening- und Laborversuchsteil ermittelten Konzentrationen an MAs und MSb, wurden Selenastrum capricornutum, Wolffia arrhiza und Lemna minor mit As- und Sb-Spezies belastet. Als Merkmal für die Schädigung der Organismen wurde für die Grünalge die Reduktion der photochemischen Effizienz des PSII genutzt und für die höheren Pflanzen die Reduktion des Wachstums über die Anzahl der Fronds. Die höchste Toxizität zeigten As(III) und MMAs(III). Die beiden As-Spezies zeigen EC-Werte im Bereich von 1 mg/l. Die EC-Werte von TMSb(V) und As(V) sind im Bereich von 10 - 10 mg/l. Sb(III), Sb(V), MMA(V), DMAs(V) und TMAs(V) zeigen EC-Werte deutlich über 10 mg/l. Für As(III) muss von einer Unterbewertung der Toxizität ausgegangen werden, da eine 50 %ige Oxidation des As(III) nach ~ 5 Tagen, unter den herrschenden Versuchsbedingungen, erfolgte. Deutlich höher in der Umweltrelevanz als die akute Toxizität ist eine Verlagerung methylierter As- und Sb- Verbindungen in echter Lösung (0,1 μm filtriert) über das Porenwasser zu beurteilen. Für Antimon traten im filtrierten Porenwasser und dem Freiwasser in 15 von 63 Fällen prozentuale Anteile der MSb am Sb > 10% auf. Dies lag für MAs- Spezies in 6 von Fällen 55 vor. Somit kommt der Methylierung insbesondere bei der Verlagerung des Antimons in Böden und Sedimenten eine wesentliche Rolle zu

Avaliação da integridade de ácaros de Demodex spp. coletados por impressão por fita adesiva

A demodicidose é uma das doenças mais frequentemente diagnosticadas na clínica de pequenos animais. Ela ocorre quando a população de ácaros residentes nos folículos pilosos e glândulas sebáceas aumenta de forma exacerbada. Possui duas formas de apresentação clínica: localizada e generalizada. A primeira é mais frequente em animais entre três e seis meses de idade, e na maioria dos casos a remissão é espontânea. A segunda acomete principalmente animais entre três e 18 meses de idade, e requer tratamento. O diagnóstico é feito por meio de exame parasitológico de pele no qual observam-se grande número de ácaros adultos ou uma maior proporção de formas imaturas. Dentre as possíveis formas de realização deste exame, a fita adesiva destacase pela facilidade na execução, ser atraumática, e poder ser realizada em locais mais delicados. Muitas vezes a rotina clínica não permite que as amostras sejam analisadas imediatamente após colheita, por isso o presente estudo teve como objetivo avaliar a integridade de ácaros de Demodex spp., coletados por meio de impressão por fita adesiva, em intervalos de 24 horas pós-colheita por cinco dias. Foram analisadas 25 amostras positivas provenientes da rotina de atendimento do DERMATOVET/ HCVUFRGS, sendo que 15 (n=60%) eram de animais que estavam em tratamento, e 10 (n=40%) de animais que foram diagnosticados no momento da consulta. Quando considerada como positiva a amostra com no mínimo um ácaro classificado como “íntegro”, a durabilidade média das amostras foi de 0,96 dias. Já quando considerado como positiva a presença de no mínimo um ácaro classificado como “degradado”, a durabilidade média das amostras foi de 2,6 dias. As amostras positivas de ácaros “íntegros” do grupo que não estava em tratamento tiveram durabilidade média de dois dias, enquanto nas amostras positivas de ácaros “degradados” do mesmo grupo foi de 3,9 dias. No grupo que estava em tratamento, a durabilidade média dos ácaros “íntegros” foi de 0,26 dias, enquanto a dos ácaros “degradados” foi de 1,73 dias. Portanto, os ácaros classificados como “íntegros” tem uma maior (e mais rápida) degradação do que aqueles classificados como “degradados”, especialmente se a amostra for oriunda de um cão em tratamento. Por fim, pode-se concluir que é possível haver um prazo na avaliação das amostras após a colheita, desde que esse tempo não seja superior a 48 horas para amostras oriundas de animais sem tratamento acaricida e 24 horas para amostras provenientes de animais sob terapia acaricida. Após estes períodos, os ácaros já não estão mais em condições íntegras, levando a uma dificuldade de visualização do parasito, e maior chance de resultados falso-negativos.Demodicosis is one of the most frequently diagnosed disease in the small animal clinic. It occurs when the population of mites living in hair follicles and sebaceous glands increases in an exacerbated form. It has two clinical forms: localized and generalized. The first one is most common in animals between three and six months old, and in most cases has spontaneous remission. The second one affects mainly animals between three and 18 months of age, and requires treatment. The diagnosis is made either by demonstrating large numbers of adult mites or by finding an increased ratio of immature forms. Among the different ways to perform the diagnosis, the acetate tape impression is distinguished by being easy to perform, atraumatic, and possible to be performed in most delicate places. Many times in the clinical routine is not possible to analize the samples right away, so this paper aimed to evaluate the integrity of Demodex spp. mites, collected through acetate tape impression at intervals of 24 hours post collection for five days. Twenty five positive samples from routine care of DERMATOVET / HCV-UFRGS were analyzed, 15 (n = 60%) were from animals that were treated, and 10 (n = 40%) from animals that have been diagnosed at the time of the appointment. During the five days, the mites were classified as "integrate" and "degraded," and the average durability of the first positive samples was 0.96 days, and the second was 2.6 days. By affecting different forms cell membranes, causing increased fragility in the parasite samples from animals that were not in treatment were compared with those from animals that were in treatment. Positive samples of mites "integrate" from the group that was not treated had an average durability of two days, while positive samples of mites "degraded" from the same group had an average durability of 3.9 days. In the group that was treated, the average durability of the "integrate" mites was 0.26 days, while that of "degraded" mites was 1.73 days. Therefore, mites classified as "integrate" has greater (and more rapid) degradation than those classified as "degraded", especially if the sample is derived from a dog being treated. Finally, we can conclude that it is possible to be a "delay" in the evaluation of samples after collection, if this time do not exceed more than 48 hours for samples from animals without acaricide treatment, and 24 hours for samples from animals under acaricide therapy. After these periods, the mites are no longer in intact conditions, making difficult the parasite observation, and a higher chance of false-negative results

Mechanical Characterisation of Cables in Different Loading Directions

The mechanical characterisation of cables can help improving the production and lifetime of various products, for example a robotic arm. Cables however form a class of composite structures, that is highly anisotropic and dissipates energy due to the reorientation of its constituents which is superimposed by the dissipation due to the deformation of the polymer components. Cables also have a degree of randomness in their structure. Moreover, the stiffness in one loading direction is coupled to the stiffness in another loading direction. In this work, experimental investigations on the mechanical properties of the cables are presented. An experimental setup has been constructed to test the cables in tensile, torsion and the bending directions individually as well as coupled to each other. Free bending tests were conducted where axial forces were compensated during the bending to dissociate the tensile and the bending properties of the cables. To apply larger tensile and torsional loads on cables a commercial testing device was also used. To characterise the influence of bending on torsion, free bending tests were conducted with a combination of torsional load. Thus, a complete mechanical characterisation of a cable is presented

A multiscale DEM–FEM coupled approach for the investigation of granules as crash-absorber in ship building

This paper covers a numerical analysis of a novel approach to increasing the crashworthiness of double hull ships. As proposed in Schöttelndreyer (Füllstoffe in der Konstruktion: ein Konzept zur Verstärkung vonSchiffsseitenhüllen, Technische Uni-versitt Hamburg, Hamburg, 2015), it involves the usage of granular materials in the cavity of the double hull ship. For the modeling of this problem, the discrete element method (DEM) is used for the granules while the finite element method is used for the ship’s structure. In order to account for the structural damage caused by collision, a gradient-enhanced ductile damage model is implemented. In addition to avoid locking, an enhanced strain-based formulation is used. For large-scale problems such as the one in the current study, modeling of all granules with realistic size can be computationally expensive. A two-scale model based on the work of Wellmann and Wriggers (Comput Methods Appl Mech Eng 205:46–58, 2012) is applied—and the region of significant localization is modeled with the DEM, while a continuum model is used for the other regions. The coupling of both discretization schemes is based on the Arlequin method. Numerical homogenization is used to estimate the material parameters of the continuum region with the granules. This involves the usage of meshless interpolation functions for the projection of particle displacement and stress onto a background mesh. Later, the volume-averaged stress and strain within the representative volume element is used to estimate the material parameters. At the end, the results from the combined numerical model are compared with the results from the experiments given in Woitzik and Düster (Ships Offshore Struct 1–12, 2020). This validates both the accuracy of the numerical model and the proposed idea of increasing the crashworthiness of double hull vessels with the granular materials. © 2021, The Author(s)

Functional characterization of the human Cdk10/Cyclin Q complex

Cyclin-dependent kinases (CDKs) are key players in cell cycle regulation and transcription. The CDK-family member Cdk10 is important for neural development and can act as a tumour suppressor, but the underlying molecular mechanisms are largely unknown. Here, we provide an in-depth analysis of Cdk10 substrate specificity and function. Using recombinant Cdk10/CycQ protein complexes, we characterize RNA pol II CTD, c-MYC and RB1 as in vitro protein substrates. Using an analogue-sensitive mutant kinase, we identify 89 different Cdk10 phosphosites in HEK cells originating from 66 different proteins. Among these, proteins involved in cell cycle, translation, stress response, growth signalling, as well as rRNA, and mRNA transcriptional regulation, are found. Of a set of pan-selective CDK- and Cdk9-specific inhibitors tested, all inhibited Cdk10/CycQ at least five times weaker than their proposed target kinases. We also identify Cdk10 as an in vitro substrate of Cdk1 and Cdk5 at multiple sites, allowing for a potential cross-talk between these CDKs. With this functional characterization, Cdk10 adopts a hybrid position in both cell cycle and transcriptional regulation

An EigenValue Stabilization Technique for Immersed Boundary Finite Element Methods in Explicit Dynamics

The application of immersed boundary methods in static analyses is often impeded by poorly cut elements (small cut elements problem), leading to ill-conditioned linear systems of equations and stability problems. While these concerns may not be paramount in explicit dynamics, a substantial reduction in the critical time step size based on the smallest volume fraction $\chi$ of a cut element is observed. This reduction can be so drastic that it renders explicit time integration schemes impractical. To tackle this challenge, we propose the use of a dedicated eigenvalue stabilization (EVS) technique. The EVS-technique serves a dual purpose. Beyond merely improving the condition number of system matrices, it plays a pivotal role in extending the critical time increment, effectively broadening the stability region in explicit dynamics. As a result, our approach enables robust and efficient analyses of high-frequency transient problems using immersed boundary methods. A key advantage of the stabilization method lies in the fact that only element-level operations are required. This is accomplished by computing all eigenvalues of the element matrices and subsequently introducing a stabilization term that mitigates the adverse effects of cutting. Notably, the stabilization of the mass matrix $\mathbf{M}_\mathrm{c}$ of cut elements -- especially for high polynomial orders $p$ of the shape functions -- leads to a significant raise in the critical time step size $\Delta t_\mathrm{cr}$. To demonstrate the efficacy of our technique, we present two specifically selected dynamic benchmark examples related to wave propagation analysis, where an explicit time integration scheme must be employed to leverage the increase in the critical time step size.Comment: 45 pages, 25 figure