Herstellung und Charakterisierung mechanisch flexibler organischer Solarzellen durch Flüssigprozessierung

In der vorliegenden Arbeit werden Elektrodensysteme für flexible organische Solarzellen entwickelt und optoelektronisch untersucht. Der Fokus liegt dabei auf einer Applikation aller funktionalen Schichten aus der Flüssigphase. Dies ermöglicht eine kosteneffektive Herstellung der Solarzellen mit großflächigen Druck- und Beschichtungsverfahren. Zudem wird die mechanische Stabilität der Elektrodensysteme sowie der gesamten Solarzelle in Zugversuchen bestimmt

Herstellung und Charakterisierung mechanisch flexibler organischer Solarzellen durch Flüssigprozessierung

In der vorliegenden Arbeit wurden Elektrodensysteme für flexible organische Solarzellen entwickelt und optoelektronisch untersucht. Der Fokus liegt dabei auf einer Applikation aller funktionalen Schichten aus der Flüssigphase. Dies ermöglicht eine kosteneffektive Herstellung der Solarzellen mit großflächigen Druck- und Beschichtungsverfahren. Zudem wurde die mechanische Stabilität der Elektrodensysteme sowie der gesamten Solarzelle in Zugversuchen bestimmt

Gewerkschaftliche Krise und Erneuerung - Labour Revitalisation Studies als globale Konversation

Der Artikel liefert einen Überblick über die Kernannahmen der labour revitalisation studies (LRS), um dann die mögliche Bereicherung dieses intellektuell-politischen Feldes durch einen stärkeren Fokus auf Erfahrungen mit gewerkschaftlicher Krise und Erneuerung im Globalen Süden zu diskutieren. Mit Bezug auf vorhandene wissenschaftliche Literatur behandelt er ein breites Spektrum empirischer Beispiele aus verschiedenen Weltregionen, geordnet entlang von vier thematischen Linien: transnationales Gewerkschaftshandeln, die Organisierung informeller und prekärer Beschäftigter, die gewerkschaftliche Auseinandersetzung mit der geschlechtlichen Natur von Arbeit und die komplexe Beziehung zwischen Gewerkschaften und dem Staat. Der Artikel argumentiert, dass die LRS als "globale Konversation" betrachtet werden sollten. Weiterhin plädiert er für eine Horizonterweiterung über traditionelle Gewerkschaftsorganisationen und ihre Handlungsrepertoires hinaus, aber auch für die Überwindung falscher Dichotomien zwischen Erneuerungsinitiativen, die "innerhalb", und anderen, die "außerhalb" etablierter Gewerkschaften entstehen.This article provides an overview of the key premises of labour revitalisation studies (LRS) and then discusses how this intellectual and political field might be enriched by an even more sustained focus on experiences of union crisis and revitalisation in the Global South. It discusses a broad range of empirical examples from a variety of world regions documented in scholarly literature, ordered along four thematic lines: transnational unionism, organising among informal and precarious workers, union engagement with the gendered nature of labour, and the complex relationship between unions and the state. On this basis, the article argues that LRS should be conceived of as a ‘global conversation’. Furthermore, it argues for broadening the view beyond traditional union organisations, their key political fields and repertoires of action, but also for overcoming false dichotomies between revitalisation initiatives that develop on the ‘outside’ and on the ‘inside’ of established unions

One or two trainees per workplace in a structured multimodality training curriculum for laparoscopic surgery? Study protocol for a randomized controlled trial – DRKS00004675

BACKGROUND: Laparoscopy training courses have been established in many centers worldwide to ensure adequate skill learning before performing operations on patients. Different training modalities and their combinations have been compared regarding training effects. Multimodality training combines different approaches for optimal training outcome. However, no standards currently exist for the number of trainees assigned per workplace. METHODS: This is a monocentric, open, three-arm randomized controlled trial. The participants are laparoscopically-naive medical students from Heidelberg University. After a standardized introduction to laparoscopic cholecystectomy (LC) with online learning modules, the participants perform a baseline test for basic skills and LC performance on a virtual reality (VR) trainer. A total of 100 students will be randomized into three study arms, in a 2:2:1 ratio. The intervention groups participate individually (Group 1) or in pairs (Group 2) in a standardized and structured multimodality training curriculum. Basic skills are trained on the box and VR trainers. Procedural skills and LC modules are trained on the VR trainer. The control group (Group C) does not receive training between tests. A post-test is performed to reassess basic skills and LC performance on the VR trainer. The performance of a cadaveric porcine LC is then measured as the primary outcome using standardized and validated ratings by blinded experts with the Objective Structured Assessment of Technical Skills. The Global Operative Assessment of Laparoscopic Surgical skills score and the time taken for completion are used as secondary outcome measures as well as the improvement of skills and VR LC performance between baseline and post-test. Cognitive tests and questionnaires are used to identify individual factors that might exert influence on training outcome. DISCUSSION: This study aims to assess whether workplaces in laparoscopy training courses for beginners should be used by one trainee or two trainees simultaneously, by measuring the impact on operative performance and learning curves. Possible factors of influence, such as the role of observing the training partner, exchange of thoughts, active reflection, model learning, motivation, pauses, and sympathy will be explored in the data analysis. This study will help optimize the efficiency of laparoscopy training courses. TRIAL REGISTRATION NUMBER: DRKS0000467

Sequential learning of psychomotor and visuospatial skills for laparoscopic suturing and knot tying – study protocol for a randomized controlled trial “The shoebox study”

Background: Laparoscopy training has become an integral part of surgical education. Suturing and knot tying is a basic, yet inherent part of many laparoscopic operations, and should be mastered prior to operating on patients. One common and standardized suturing technique is the C-loop technique. In the standard training setting, on a box trainer, the trainee learns the psychomotor movements of the task and the laparoscopic visuospatial orientation simultaneously. Learning the psychomotor and visuospatial skills separately and sequentially may offer a more time-efficient alternative to the current standard of training. Methods: This is a monocentric, two-arm randomized controlled trial. The participants are medical students in their clinical years (third to sixth year) at Heidelberg University who have not previously partaken in a laparoscopic training course lasting more than 2 hours. A total of 54 students are randomized into one of two arms in a 1:1 ratio to sequential learning (group 1) or control (group 2). Both groups receive a standardized introduction to the training center, laparoscopic instruments, and C-loop technique. Group 1 learn the C-loop using a transparent shoebox, thus only learning the psychomotor skills. Once they reach proficiency, they then perform the same knot tying procedure on a box trainer with standard laparoscopic view, where they combine their psychomotor skills with the visuospatial orientation inherent to laparoscopy. Group 2 learn the C-loop using solely a box trainer with standard laparoscopic view until they reach proficiency. Trainees work in pairs and time is recorded for each attempt. The primary outcome is mean total training time for each group. Secondary endpoints include procedural and knot quality subscore differences. Tertiary endpoints include studying the influence of gender and video game experience on performance. Discussion: This study addresses whether the learning of the psychomotor and visuospatial aspects of laparoscopic suturing and knot tying is optimal sequentially or simultaneously, by assessing total training time, procedural, and knot quality differences between the two groups. It will improve the efficiency of future laparoscopic suturing courses and may serve as an indicator for laparoscopic training in a broader context, i.e., not only for suturing and knot tying. Trial registration: This trial was registered on 12 August 2015 with the trial registration number DRKS00008668

Semantic segmentation of surgical hyperspectral images under geometric domain shifts

Robust semantic segmentation of intraoperative image data could pave the way for automatic surgical scene understanding and autonomous robotic surgery. Geometric domain shifts, however, although common in real-world open surgeries due to variations in surgical procedures or situs occlusions, remain a topic largely unaddressed in the field. To address this gap in the literature, we (1) present the first analysis of state-of-the-art (SOA) semantic segmentation networks in the presence of geometric out-of-distribution (OOD) data, and (2) address generalizability with a dedicated augmentation technique termed "Organ Transplantation" that we adapted from the general computer vision community. According to a comprehensive validation on six different OOD data sets comprising 600 RGB and hyperspectral imaging (HSI) cubes from 33 pigs semantically annotated with 19 classes, we demonstrate a large performance drop of SOA organ segmentation networks applied to geometric OOD data. Surprisingly, this holds true not only for conventional RGB data (drop of Dice similarity coefficient (DSC) by 46 %) but also for HSI data (drop by 45 %), despite the latter's rich information content per pixel. Using our augmentation scheme improves on the SOA DSC by up to 67 % (RGB) and 90 % (HSI) and renders performance on par with in-distribution performance on real OOD test data. The simplicity and effectiveness of our augmentation scheme makes it a valuable network-independent tool for addressing geometric domain shifts in semantic scene segmentation of intraoperative data. Our code and pre-trained models are available at https://github.com/IMSY-DKFZ/htc.Comment: The first two authors (Jan Sellner and Silvia Seidlitz) contributed equally to this pape