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OPEN FAU

Online publication system of Friedrich-Alexander-Universität Erlangen-Nürnberg

The online publication system OPEN FAU is the central publication platform for Open Access publishing for all members of Friedrich-Alexander-Universität. Qualified works from research and teaching may be published here free of charge, either as a primary or secondary publication. The full texts are permanently available worldwide and are findable and citable via catalogues and search engines.


To search for documents in OPEN FAU, please select "Search" (via the magnifying glass at the top right); this will provide you with various search options. If you want to publish a document, go to "Login" and "My Publications". Then drag you document into the field provided and enter the metadata. In just a few steps, you can submit your document. Please note our guidelines, the publication contract and FAQs.

 

Recent Submissions

Article
Open Access
Left Atrial Appendage Occlusion on a Beating Heart during Minimally Invasive Valve Surgery Using an Aortic Endoclamp: A Case Report
(MDPI, 2023-09-30) Suleiman, Mathieu N.; Kaemmerer, Ann-Sophie; Fechner, Jörg; Nooh, Ehab; Weyand, Michael; Heim, Christian; La Canna, Giovanni

Concomitant LAA occlusion has been shown to be an effective and safe treatment for patients with atrial fibrillation during cardiac surgery to prevent embolic stroke. Minimally invasive procedures are challenging due to restricted access to and visibility of the surgical site. Also, aortic endoclamping has been developed as an alternative surgical approach to exoclamping. The aim of this article is to demonstrate the method of beating heart LAA occlusion with the Atriclip® (AtriCure, Mason, OH, USA) device during minimally invasive mitral valve surgery while using the endoclamping alternative for aortic cross-clamping.

Doctoral thesis
Open Access
APSified OCT-angiography analysis: macula vessel density in healthy eyes during office hours
(2024) Müller, Meike; Mardin, Christian; Hohberger, Bettina
Hintergrund und Ziele Die optische Kohärenztomographie-Angiographie (OCT-A) als bildgebendes Verfahren stellt eine nicht-invasive Methode zur quantitativen Bestimmung der retinochoroidalen Durchblutung dar. Sie erlaubt es, in vivo Aufnahmen der Gefäßdichte der Makula sowie der peripapillären Region zu generieren. Für eine korrekte Auswertung und Interpretation der so gewonnenen OCT-A-Daten ist es notwendig, mögliche Einflussfaktoren, wie beispielsweise tageszeitliche Schwankungen, zu kennen. Ziel der vorliegenden Studie war es deshalb, zirkadiane Änderungen der Makula Gefäßdichte (VD) gesunder Erwachsener während zuvor festgelegter Bürozeiten von 9 bis 21 Uhr zu bestimmen. Zusätzlich wurden Änderungen der Achsenlänge (AL) und der subfoveolarer Aderhautdicke (CT) untersucht. Methoden In der prospektiven Studie wurden 30 Augen von 30 gesunden Erwachsenen (Durchschnittsalter 28,7 ± 11,8 Jahre, Altersspanne 19-60 Jahre) untersucht. Bei jedem Probanden wurden innerhalb eines Tages an drei zuvor festgelegten Zeitpunkten um 9 Uhr, 15 Uhr und 21 Uhr die AL, die subfoveale CT sowie die dreischichtige Makula VD (oberflächlicher Gefäßplexus (SVP), intermediärer Kapillarplexus (ICP) und tiefer Kapillarplexus (DCP)) bestimmt. Die VD wurde anschließend für jede der drei Schichten jeweils gesamt sowie nach Aufteilung in 12 Sektoren auch einzeln ausgewertet. Zur besseren intra- und interindividuellen Vergleichbarkeit der Scans wurde für die quantitative OCT-A-Analyse das neue „Anatomical Positioning System“ (APS, Teil der Glaucoma Module Premium Edition [GMPE], Heidelberg Engineering, Deutschland) verwendet, welches durch Ausrichtung der Scans anhand anatomischer Landmarken eine Analyse identischer Netzhautbereiche ermöglichte. Ergebnisse und Beobachtungen Während des Untersuchungszeitraums blieb die mittlere Gesamt VD aller Augen in SVP, ICP und DCP konstant (p>0,05). Ebenso ergab die Auswertung von AL und CT keine statistisch signifikanten Veränderungen im zeitlichen Verlauf (p>0,05). Vielmehr wurde eine große interindividuelle Varianz der einzelnen VD-Kurven mit unterschiedlichen Spitzenzeiten beobachtet. Im Gegensatz zur Gesamt VD, änderte sich jedoch die sektorielle VD in Abhängigkeit von der Uhrzeit in allen drei Schichten mit einem Anstieg in SVP zwischen 9 Uhr und 21 Uhr (p=0,003), in ICP zwischen 15 Uhr und 21 Uhr (p=0,000) und in DCP zwischen 9 Uhr und 21 Uhr (p=0,048) sowie 15 Uhr und 21 Uhr (p=0,000). Schlussfolgerungen und Diskussion In der vorliegenden Studie schienen in der Kohorte die mittlere Gesamt VD, die subfoveale CT und die AL über die drei Messzeiten hinweg konstant zu bleiben. Dagegen konnten in einer regionalen VD-Analyse gewisse zeitliche Änderungen festgestellt werden. Demnach kann ein zirkadianer Einfluss auf die kapillare Mikrozirkulation nicht ausgeschlossen werden. Die Ergebnisse zeigen die Bedeutung einer detaillierten Analyse der VD sowohl in verschiedenen Sektoren als auch einzelnen Gefäßschichten. Interessant ist darüber hinaus, dass das Muster der tageszeitlichen Schwankungen interindividuell zu variieren scheint, so dass bei der Auswertung dieser Parameter im klinischen Alltag ein patientenspezifisches Fluktuationsmuster berücksichtigt werden sollte.
Article
Open Access
The Effect of Digital Mindfulness Interventions on Depressive, Anxiety, and Stress Symptoms in Pregnant Women: A Systematic Review and Meta-Analysis
(MDPI, 2023-09-01) Mefrouche, Monique L.; Siegmann, Eva-Maria; Böhme, Stephanie; Berking, Matthias; Kornhuber, Johannes; Morales Rodríguez, Francisco Manuel; Martínez, Africa Martos

Introduction. Pregnancy is a unique time in a woman’s life that can be both exciting and challenging. It is also a period that can be associated with significant stress, anxiety, and depression, which can have negative consequences for both the mother and the baby. Mindfulness interventions are known to be a well-suited treatment and prevention method for psychiatric symptoms in pregnancy, and web-based applications have been explored. We here present an up-to-date systematic review and meta-analysis of randomized–controlled trials to investigate the effect of digital-based mindfulness interventions on depressive, anxiety, and stress symptoms during pregnancy. Methods. The systematic literature search and data extraction was performed by two independent raters. It resulted in 13 eligible studies overall comprising 1373 participants. We conducted random-effects meta-analyses for depressive, anxiety, and stress symptoms after completion of a digital mindfulness intervention (compared to a control group). Results. Digital mindfulness intervention methods were significantly able to reduce depression (g = −0.47, 95% CI [−0.9; −0.09]) and anxiety symptoms (g = −0.41, 95% CI [−0.77; −0.05]), but not stress symptoms. These effects were moderated by the attrition rate (βDepression = 0.025, pDepression < 0.01; βAnxiety = 0.022, pAnxiety < 0.01; βStress = 0.022, pStress < 0.01). Primiparity also had a significant influence on the intervention effect regarding depression symptoms (β = 0.033, p = 0.024). Conclusions. Digital mindfulness interventions are a promising method to reduce mental health symptoms in pregnant women. We identified certain parameters moderating this effect, for example, primiparity and the attrition rate.

Article
Open Access
Robust γ-TiAl Dual Microstructure Concept by Advanced Electron Beam Powder Bed Fusion Technology
(MDPI, 2023-09-05) Reith, Marcel; Franke, Martin; Körner, Carolin; Narayanan, Jinoop Arackal; Anil Kumar, V.; Paul, Christ Prakash

The dual microstructure concept for gamma titanium aluminides (γ-TiAl) processed via electron beam–powder bed fusion (PBF-EB) provides a huge potential for more efficient jet turbine engines. While the concept is feasible and the mechanical properties are promising, there are still some challenges. For an industrial application, the heat treatment window has to match the conditions in industrial furnaces. This study shows how the required heat treatment window can be achieved via advanced PBF-EB technology. Through using an electron beam with 150 kV acceleration voltage, the difference in aluminum between the designed aluminum-rich and aluminum-lean regions of the part is increased. Moreover, the aluminum content within each of these regions, respectively, is more homogenous compared to the 60 kV acceleration voltage. This combination provides a heat treatment window of 25 °C, enabling the industrial application of the dual microstructure concept for γ-TiAl.

Article
Open Access
Limitations of the Check Calculation for Tooth Deformation of Plastic Gears According to Gear Design Guideline VDI 2736
(MDPI, 2023-09-18) Herzog, Christoph; Drummer, Dietmar; Sorrentino, Andrea

An in situ gear test rig has been developed at the Institute of Polymer Technology (LKT) to characterize the deformation of plastic gears during operation. It analyses timing differences between following index pulses of rotary encoders on the input and output shaft. This measurement principle enables the continuous measurement of the elastic tooth deformation and permanent deformations and wear at operating speed by switching between a high and low torque. Gear tests using a steel-polybutylene terephthalate (PBT) gear set were performed at different rotational speeds and tooth temperatures to analyze the tooth deformation during operation. The results were compared to the calculated deformation according to gear design guideline VDI 2736. Moreover, the results of the gear tests were correlated with the results of a dynamomechanical analysis (DMA). Both, the DMA and the in situ gear tests show that the effect of temperature on deformation is much higher than the effect of frequency or rotational speed. However, the experimentally measured tooth deformation is significantly higher (up to 50%) than the calculated at lower speed. Thus, the check calculation according to VDI 2736 underestimates the actual tooth deformation at lower speeds. Therefore, the guideline should be adjusted in the future.