Publikationsserver der Ostbayerischen Technischen Hochschule Regensburg
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Clinical Relevance of Platelet-Leukocyte Aggregates and Platelet P-Selectin Expression During Venovenous Extracorporeal Membrane Oxygenation
No full textThrombosis continues to be a significant complication during venovenous extracorporeal membrane oxygenation (V-V ECMO). Platelet activation markers might serve as indicators of inflammation and thrombogenesis. The aim was to identify these markers in ECMO patients. Blood from 10 ECMO patients (before, during, after ECMO) and 11 healthy volunteers were collected to determine platelet-neutrophil-aggregates (PNAs), platelet-monocyte-aggregates (PMAs), fibrinogen-binding, and P-selectin-expression on platelets by flow cytometry. Critical illness was associated with significantly elevated levels of PNAs and PMAs, increased P-selectin expression, reduced fibrinogen-binding, and restricted activation of platelets. Although PNAs and PMAs decreased significantly within 2 hours after the initiation of ECMO and remained at those levels, ECMO did not affect basal P-selectin expression and fibrinogen-binding. These results correlated with coagulation activation. Platelet markers before ECMO were not indicators for an imminent system exchange and end of therapy. In conclusion, platelet dysfunction during ECMO was mainly attributed to the critical illness. Extracorporeal membrane oxygenation support strengthened the restricted response of platelets to exogenous agonists (P-selectin). Furthermore, a decrease in PNAs/PMAs after ECMO started identified a reduced inflammatory response. There was no correlation of analyzed platelet parameters with the incidence of thrombotic complications
Optimizing Neural Data Analysis: Determining Minimum Recording Length for Unambigous Signal Processing
No full textAdvanced silicon electrode arrays facilitate the recording of thousands of neurons, generating extensive neural data that imposes a significant burden on researchers and processing algorithms. Thus, real-time analysis pipelines are gaining increasing value, while at the same time having to deal with non-stationary and noisy data. We intend to apply Machine Learning (ML) algorithms to a dense set of recordings from rat brains in order to prepare a functional atlas, correlating neuronal signals with anatomical position. While doing so, we needed to decide on a rational way which recording snippet length would best represent the original, longer source sequence and thus suffices to be further processed for anatomical correlation. We implemented an algorithm to evaluate the spectral information of systematically length varied records based on similarity to the original record. For our dataset a recording duration of 3 seconds satisfied moderate requirements across all channels, thus allowing us to reduce computational load for ongoing ML classification of microprobe sourced electrophysiologic signals
The Sound Reduction Index of Homogeneous Building Elements according to Annex B of ISO 12354-1 – Discussion and Proposal for Changes
No full textAnnex B of ISO 12354-1:2017 describes a procedure for the calculation of the frequency-dependent sound reduction index of homogeneous building elements such as concrete floors or masonry walls. With the introduction of EN 12354-5:2023 and an upcoming change in DIN 4109-2 regarding the calculation of sound levels due to service equipment, it is anticipated that the practical relevance and usage of Annex B will increase in the future. For this reason, the procedure has recently been investigated by an informal working group of academics from several German universities. It was found that Annex B contains some errors, missing references, and ambiguities in the calculation procedure. Based on these discussions, some changes were proposed to the committee responsible for the standard (CEN/TC 126/WG 2). While the general calculation procedure was left unchanged, the proposed changes focus on the influence of shear deformation, the radiation factor for free waves, a moving average function to limit the variability in the coincidence region, and the calculation examples provided in the annex. This contribution provides an overview of the procedure, presents some background information on the underlying theory, and discusses the proposed changes
TransConv: a lightweight architecture based on transformers and convolutional neural networks for adenocarcinoma and Barrett’s esophagus identification
No full textBarrett’s esophagus, also known as BE, is commonly associated with repeated exposure to stomach acid. If not treated properly, it may evolve into esophageal adenocarcinoma, aka esophageal cancer. This paper proposes TransConv, a hybrid architecture that benefits from features learned by pre-trained vision transformers (ViTs) and convolutional neural networks (CNNs), followed by a shallow neural network composed of three normalizations, ReLU activations, and fully connected layers, and a SoftMax head to distinguish between BE and esophageal cancer. TransConv is designed to be training-lightweight, and for the ViT and CNN backbone models, weights are kept frozen during training, i.e., the primary goal of TransConv is to learn the weights of the fully connected layer from both backbones only, avoiding the burden of updating their weights but still learning their final descriptions for the lightweight convolutional model. We report promising results with low computational training costs in two datasets, one public and another private. From our achievements, TransConv was able to deliver balanced accuracy results around 85% and 86% for each evaluated dataset, respectively, in a design that required only 50 epochs of model training, a very reduced number compared to state-of-the-art conducted studies in the same domain
Material Characterization Using Waveguide Measurement Technique for the Development of Textile Antennas
No full textSignificant advances in using conductive textiles have been made over the past two decades, particularly in knitted fabrics. The aim is to deepen understanding of how knitted structures, especially those with hybrid yarns containing fine conductive elements (microwires), interact with electromagnetic fields. To establish simulation models that align with subsequent measurements, it is crucial to determine the dielectric properties, specifically relative permittivity and loss tangent/conductivity. This research investigates whether knitted structures with hybrid yarns exhibit anisotropic permittivity, meaning different dielectric properties along orthogonal axes within the fabric plane. These properties were measured using a waveguide technique’ whereby the structures were rotated by 90° to observe changes. The results demonstrate that the knitted structure exhibits metallic-like reflective behavior in one direction, while rotation leads to dielectric material characteristics. This effect is influenced by the number of conductive microwires and the materials used for these wires, such as silver-plated copper or bronze
Nachhaltigkeit und Effektivität von Kompressionsmaßnahmen in Prävention des Postthrombotischen Syndroms
No full textEtwa 20–50 % der Patientinnen und Patienten mit akuter tiefer Beinvenenthrombose entwickeln in den ersten 5 Jahren postthrombotische Komplikationen, die durch Schwellung, Schmerzen und eingeschränkter Lebensqualität zu Frühberentungen führen können. Eine frühzeitig eingeleitete Therapie mit Antikoagulanzien fördert die Rekanalisation thrombosierter Venen in der Frühphase und verhindert Rezidivthrombosen im Verlauf. Der Nutzen der Kompressionstherapie wird immer wieder diskutiert. Ziel des Reviews ist, Nachhaltigkeit und Effektivität zum Einsatz von Kompressionsmaßnahmen in Prävention des Postthrombotischen Syndroms darzustellen.
Die Literaturrecherche ergibt 4375 Treffer, 130 Studien und Fachartikel werden eingeschlossen. Zwei randomisierte kontrollierte Studien (RCTs) zeigen eine klare Empfehlung für Kompressionsmaßnahmen und Mobilisation in der Akutphase einer tiefen Beinvenenthrombose. zwei RCTs bewerten die präventive Wirkung von Kompressionsstrümpfen und zeigen, dass sich die Rate postthrombotischer Komplikationen um etwa 50 % reduzieren lässt (p < 0,001; p < 0,001 und HR 0,49 (95 %-KI, 0,29–0,84; p = 0,011)). Zwei RCTs können beim Vergleich von Kompressions- versus Placebostrümpfen keine signifikante Besserung postthrombotischer Beschwerden nachweisen (HR 1,13, 95 %-KI 0,73–1,76; p = 0,58), beide Publikationen sind kritisch zu hinterfragen. Ein RCT stellt dar, dass die Höhe der Kompressionsstrümpfe keine signifikanten postthrombotischen Auswirkungen zeigen (p = 0,017) und zwei RCTs belegen, dass eine individualisierte Therapie mit Kompressionsstrümpfen der Standardtherapiedauer von 24 Monaten nicht unterlegen ist. Voraussetzung für die Effektivität ist die korrekte Applikation
Ressourcen weiter denken. Zur Zeitlichkeit der Sozialen Arbeit im Kontext der Nachhaltigkeitstransformation
No full textSoziale Arbeit kann aus der Perspektive einer zeitökologisch fundierten Resonanztheorie einen Beitrag zur Nachhaltigkeitstransformation leisten. Zugrunde liegt die These, dass für die Soziale Arbeit ein theoretischer Ansatz gewinnbringend ist, der die Zeitlichkeit von Mensch, Gesellschaft und Natur – und damit auch der Nachhaltigen Entwicklung und der Sozialen Arbeit selbst – ins Zentrum stellt. Vor diesem Hintergrund werden die Zeitlichkeit der Nachhaltigen Entwicklung und der Sozialen Arbeit im Kontext der Nachhaltigkeitstransformation herausgearbeitet, theoretische Ansätze zu Zeit und Ressourcen diskutiert und eine mögliche Verknüpfung beider Begriffe am Beispiel von Resonanz, Bildung und Zeit skizziert
In-situ optical coherence tomography for spatio-temporal analysis of melt pool crystallization in absorber-free laser transmission welding of polymers
No full textFestigkeitsbewertung von hochbeanspruchten Kupferkomponenten
No full textEs wird gezeigt, wie durch ein ganzheitliches Konzept, beginnend mit der Modellerstellung eines umfangreichen FE-Berechnungsmodells bis hin zur Festigkeitsbewertung unter Verwendung speziell ermittelter Werkstoffkenndaten, die Betriebssicherheit von hochbeanspruchten Kupferkomponenten sichergestellt werden kann.
Mit den durchgeführten Werkstoffversuchsreihen an wärmebehandelten und weichgeglühten Kupferproben aus Cu-ETP R250 wurden neben den Standard-Werkstoffkenndaten wie Streckgrenze Rp, Zugfestigkeit Rm, Bruchdehnung A und Elastizitätsmodul E Parameter zur Beschreibung des Werkstoffverhaltens bei zyklischer Belastung bestimmt. Zusätzlich wurde wurde in Abhängigkeit der Wärmebehandlung und der damit verbundenen Ver- oder Entfestigung die Schwingfestigkeit eruiert. Somit ist mit der vorgestellten methodischen Vorgehensweise unter Verwendung tatsächlicher Werkstoffsteifigkeiten und umfangreicher Schwingfestigkeitsdaten eine Betriebsfestigkeitsbewertung möglich
