Human-Robot Gym: Benchmarking Reinforcement Learning in Human-Robot Collaboration

Deep reinforcement learning (RL) has shown promising results in robot motion planning with first attempts in human-robot collaboration (HRC). However, a fair comparison of RL approaches in HRC under the constraint of guaranteed safety is yet to be made. We, therefore, present human-robot gym, a benchmark for safe RL in HRC. Our benchmark provides eight challenging, realistic HRC tasks in a modular simulation framework. Most importantly, human-robot gym includes a safety shield that provably guarantees human safety. We are, thereby, the first to provide a benchmark to train RL agents that adhere to the safety specifications of real-world HRC. This bridges a critical gap between theoretic RL research and its real-world deployment. Our evaluation of six environments led to three key results: (a) the diverse nature of the tasks offered by human-robot gym creates a challenging benchmark for state-of-the-art RL methods, (b) incorporating expert knowledge in the RL training in the form of an action-based reward can outperform the expert, and (c) our agents negligibly overfit to training data

First report of\u3cem\u3e Lissothus occidentalis\u3c/em\u3e Vachon, 1950 (Scorpiones: Buthidae) from Morocco and Western Sahara, with notes on ecology and captive breeding

Genus Lissothus Vachon, 1948 represented by L. occidentalis Vachon, 1950 is reported for the first time from four localities in Morocco and the Western Sahara. We provide a revised diagnosis of L. occidentalis, fully complemented with color photos of live and preserved specimens. Hemispermatophore is also illustrated and described in detail. Furthermore, we describe aspects of the ecology of this species, and provide photos of collection sites and habitats. We also report on the reproductive biology of this species based on captive breeding and rearing. and provide the first envenomation report for the species

Modeling the Ultrasonic Softening Effect for Robust Copper Wire Bonding

Unger A, Sextro W, Althoff S, et al. Modeling the Ultrasonic Softening Effect for Robust Copper Wire Bonding. In: 8th International Conference on Integrated Power Electronics Systems, Proceedings, February, 25-27, 2014 Nuremberg/Germany. ETG-Fachbericht. Vol 141. VDE-Verlag; 2014.In power electronics, ultrasonic wire bonding is used to connect the electrical terminals of power modules. To implement a self-optimization technique for ultrasonic wire bonding machines, a model of the process is essential. This model needs to include the so called ultrasonic softening effect. It is a key effect within the wire bonding process primarily enabling the robust interconnection between the wire and a substrate. However, the physical modeling of the ultrasonic softening effect is notoriously difficult because of its highly non-linear character and the absence of a proper measurement method. In a first step, this paper validates the importance of modeling the ultrasonic softening by showing its impact on the wire deformation characteristic experimentally. In a second step, the paper presents a data-driven model of the ultrasonic softening effect which is constructed from data using machine learning techniques. A typical caveat of data-driven modeling is the need for training data that cover the considered domain of process parameters in order to achieve accurate generalization of the trained model to new process configurations. In practice, however, the space of process parameters can only be sampled sparsely. In this paper, a novel technique is applied which enables the integration of prior knowledge about the process into the datadriven modeling process. It turns out that this approach results in accurate generalization of the data-driven model to novel process parameters from sparse data

EDGAR: An Autonomous Driving Research Platform -- From Feature Development to Real-World Application

While current research and development of autonomous driving primarily focuses on developing new features and algorithms, the transfer from isolated software components into an entire software stack has been covered sparsely. Besides that, due to the complexity of autonomous software stacks and public road traffic, the optimal validation of entire stacks is an open research problem. Our paper targets these two aspects. We present our autonomous research vehicle EDGAR and its digital twin, a detailed virtual duplication of the vehicle. While the vehicle's setup is closely related to the state of the art, its virtual duplication is a valuable contribution as it is crucial for a consistent validation process from simulation to real-world tests. In addition, different development teams can work with the same model, making integration and testing of the software stacks much easier, significantly accelerating the development process. The real and virtual vehicles are embedded in a comprehensive development environment, which is also introduced. All parameters of the digital twin are provided open-source at https://github.com/TUMFTM/edgar_digital_twin

Survival benefit with checkpoint inhibitors versus chemotherapy is modified by brain metastases in patients with recurrent small cell lung cancer

IntroductionSmall cell lung cancer (SCLC) is a rapidly growing malignancy with early distant metastases. Up to 70% will develop brain metastases, and the poor prognosis of these patients has not changed considerably. The potential of checkpoint inhibitors (CPI) in treating recurrent (r/r) SCLC and their effect on brain metastases remain unclear.MethodsIn this retrospective multicenter study, we analyzed r/r SCLC patients receiving second or further-line CPI versus chemotherapy between 2010 and 2020. We applied multivariable-adjusted Cox regression analysis to test for differences in 1-year mortality and real-world progression. We then used interaction analysis to evaluate whether brain metastases (BM) and/or cranial radiotherapy (CRT) modified the effect of CPI versus chemotherapy on overall survival.ResultsAmong 285 patients, 99 (35%) received CPI and 186 (65%) patients received chemotherapy. Most patients (93%) in the CPI group received nivolumab/ipilimumab. Chemotherapy patients were entirely CPI-naïve and only one CPI patient had received atezolizumab for first-line treatment. CPI was associated with a lower risk of 1-year mortality (adjusted Hazard Ratio [HRadj] 0.59, 95% CI 0.42 to 0.82, p=0.002). This benefit was modified by BM and CRT, indicating a pronounced effect in patients without BM (with CRT: HRadj 0.34, p=0.003; no CRT: HRadj 0.50, p=0.05), while there was no effect in patients with BM who received CRT (HRadj 0.85, p=0.59).ConclusionCPI was associated with a lower risk of 1-year mortality compared to chemotherapy. However, the effect on OS was significantly modified by intracranial disease and radiotherapy, suggesting the benefit was driven by patients without BM

Insights into Land Plant Evolution Garnered from the Marchantia polymorpha Genome.

The evolution of land flora transformed the terrestrial environment. Land plants evolved from an ancestral charophycean alga from which they inherited developmental, biochemical, and cell biological attributes. Additional biochemical and physiological adaptations to land, and a life cycle with an alternation between multicellular haploid and diploid generations that facilitated efficient dispersal of desiccation tolerant spores, evolved in the ancestral land plant. We analyzed the genome of the liverwort Marchantia polymorpha, a member of a basal land plant lineage. Relative to charophycean algae, land plant genomes are characterized by genes encoding novel biochemical pathways, new phytohormone signaling pathways (notably auxin), expanded repertoires of signaling pathways, and increased diversity in some transcription factor families. Compared with other sequenced land plants, M. polymorpha exhibits low genetic redundancy in most regulatory pathways, with this portion of its genome resembling that predicted for the ancestral land plant. PAPERCLIP

Human Practice. Digital Ecologies. Our Future. : 14. Internationale Tagung Wirtschaftsinformatik (WI 2019) : Tagungsband

Erschienen bei: universi - Universitätsverlag Siegen. - ISBN: 978-3-96182-063-4Aus dem Inhalt: Track 1: Produktion & Cyber-Physische Systeme Requirements and a Meta Model for Exchanging Additive Manufacturing Capacities Service Systems, Smart Service Systems and Cyber- Physical Systems—What’s the difference? Towards a Unified Terminology Developing an Industrial IoT Platform – Trade-off between Horizontal and Vertical Approaches Machine Learning und Complex Event Processing: Effiziente Echtzeitauswertung am Beispiel Smart Factory Sensor retrofit for a coffee machine as condition monitoring and predictive maintenance use case Stakeholder-Analyse zum Einsatz IIoT-basierter Frischeinformationen in der Lebensmittelindustrie Towards a Framework for Predictive Maintenance Strategies in Mechanical Engineering - A Method-Oriented Literature Analysis Development of a matching platform for the requirement-oriented selection of cyber physical systems for SMEs Track 2: Logistic Analytics An Empirical Study of Customers’ Behavioral Intention to Use Ridepooling Services – An Extension of the Technology Acceptance Model Modeling Delay Propagation and Transmission in Railway Networks What is the impact of company specific adjustments on the acceptance and diffusion of logistic standards? Robust Route Planning in Intermodal Urban Traffic Track 3: Unternehmensmodellierung & Informationssystemgestaltung (Enterprise Modelling & Information Systems Design) Work System Modeling Method with Different Levels of Specificity and Rigor for Different Stakeholder Purposes Resolving Inconsistencies in Declarative Process Models based on Culpability Measurement Strategic Analysis in the Realm of Enterprise Modeling – On the Example of Blockchain-Based Initiatives for the Electricity Sector Zwischenbetriebliche Integration in der Möbelbranche: Konfigurationen und Einflussfaktoren Novices’ Quality Perceptions and the Acceptance of Process Modeling Grammars Entwicklung einer Definition für Social Business Objects (SBO) zur Modellierung von Unternehmensinformationen Designing a Reference Model for Digital Product Configurators Terminology for Evolving Design Artifacts Business Role-Object Specification: A Language for Behavior-aware Structural Modeling of Business Objects Generating Smart Glasses-based Information Systems with BPMN4SGA: A BPMN Extension for Smart Glasses Applications Using Blockchain in Peer-to-Peer Carsharing to Build Trust in the Sharing Economy Testing in Big Data: An Architecture Pattern for a Development Environment for Innovative, Integrated and Robust Applications Track 4: Lern- und Wissensmanagement (e-Learning and Knowledge Management) eGovernment Competences revisited – A Literature Review on necessary Competences in a Digitalized Public Sector Say Hello to Your New Automated Tutor – A Structured Literature Review on Pedagogical Conversational Agents Teaching the Digital Transformation of Business Processes: Design of a Simulation Game for Information Systems Education Conceptualizing Immersion for Individual Learning in Virtual Reality Designing a Flipped Classroom Course – a Process Model The Influence of Risk-Taking on Knowledge Exchange and Combination Gamified Feedback durch Avatare im Mobile Learning Alexa, Can You Help Me Solve That Problem? - Understanding the Value of Smart Personal Assistants as Tutors for Complex Problem Tasks Track 5: Data Science & Business Analytics Matching with Bundle Preferences: Tradeoff between Fairness and Truthfulness Applied image recognition: guidelines for using deep learning models in practice Yield Prognosis for the Agrarian Management of Vineyards using Deep Learning for Object Counting Reading Between the Lines of Qualitative Data – How to Detect Hidden Structure Based on Codes Online Auctions with Dual-Threshold Algorithms: An Experimental Study and Practical Evaluation Design Features of Non-Financial Reward Programs for Online Reviews: Evaluation based on Google Maps Data Topic Embeddings – A New Approach to Classify Very Short Documents Based on Predefined Topics Leveraging Unstructured Image Data for Product Quality Improvement Decision Support for Real Estate Investors: Improving Real Estate Valuation with 3D City Models and Points of Interest Knowledge Discovery from CVs: A Topic Modeling Procedure Online Product Descriptions – Boost for your Sales? Entscheidungsunterstützung durch historienbasierte Dienstreihenfolgeplanung mit Pattern A Semi-Automated Approach for Generating Online Review Templates Machine Learning goes Measure Management: Leveraging Anomaly Detection and Parts Search to Improve Product-Cost Optimization Bedeutung von Predictive Analytics für den theoretischen Erkenntnisgewinn in der IS-Forschung Track 6: Digitale Transformation und Dienstleistungen Heuristic Theorizing in Software Development: Deriving Design Principles for Smart Glasses-based Systems Mirroring E-service for Brick and Mortar Retail: An Assessment and Survey Taxonomy of Digital Platforms: A Platform Architecture Perspective Value of Star Players in the Digital Age Local Shopping Platforms – Harnessing Locational Advantages for the Digital Transformation of Local Retail Outlets: A Content Analysis A Socio-Technical Approach to Manage Analytics-as-a-Service – Results of an Action Design Research Project Characterizing Approaches to Digital Transformation: Development of a Taxonomy of Digital Units Expectations vs. Reality – Benefits of Smart Services in the Field of Tension between Industry and Science Innovation Networks and Digital Innovation: How Organizations Use Innovation Networks in a Digitized Environment Characterising Social Reading Platforms— A Taxonomy-Based Approach to Structure the Field Less Complex than Expected – What Really Drives IT Consulting Value Modularity Canvas – A Framework for Visualizing Potentials of Service Modularity Towards a Conceptualization of Capabilities for Innovating Business Models in the Industrial Internet of Things A Taxonomy of Barriers to Digital Transformation Ambidexterity in Service Innovation Research: A Systematic Literature Review Design and success factors of an online solution for cross-pillar pension information Track 7: IT-Management und -Strategie A Frugal Support Structure for New Software Implementations in SMEs How to Structure a Company-wide Adoption of Big Data Analytics The Changing Roles of Innovation Actors and Organizational Antecedents in the Digital Age Bewertung des Kundennutzens von Chatbots für den Einsatz im Servicedesk Understanding the Benefits of Agile Software Development in Regulated Environments Are Employees Following the Rules? On the Effectiveness of IT Consumerization Policies Agile and Attached: The Impact of Agile Practices on Agile Team Members’ Affective Organisational Commitment The Complexity Trap – Limits of IT Flexibility for Supporting Organizational Agility in Decentralized Organizations Platform Openness: A Systematic Literature Review and Avenues for Future Research Competence, Fashion and the Case of Blockchain The Digital Platform Otto.de: A Case Study of Growth, Complexity, and Generativity Track 8: eHealth & alternde Gesellschaft Security and Privacy of Personal Health Records in Cloud Computing Environments – An Experimental Exploration of the Impact of Storage Solutions and Data Breaches Patientenintegration durch Pfadsysteme Digitalisierung in der Stressprävention – eine qualitative Interviewstudie zu Nutzenpotenzialen User Dynamics in Mental Health Forums – A Sentiment Analysis Perspective Intent and the Use of Wearables in the Workplace – A Model Development Understanding Patient Pathways in the Context of Integrated Health Care Services - Implications from a Scoping Review Understanding the Habitual Use of Wearable Activity Trackers On the Fit in Fitness Apps: Studying the Interaction of Motivational Affordances and Users’ Goal Orientations in Affecting the Benefits Gained Gamification in Health Behavior Change Support Systems - A Synthesis of Unintended Side Effects Investigating the Influence of Information Incongruity on Trust-Relations within Trilateral Healthcare Settings Track 9: Krisen- und Kontinuitätsmanagement Potentiale von IKT beim Ausfall kritischer Infrastrukturen: Erwartungen, Informationsgewinnung und Mediennutzung der Zivilbevölkerung in Deutschland Fake News Perception in Germany: A Representative Study of People’s Attitudes and Approaches to Counteract Disinformation Analyzing the Potential of Graphical Building Information for Fire Emergency Responses: Findings from a Controlled Experiment Track 10: Human-Computer Interaction Towards a Taxonomy of Platforms for Conversational Agent Design Measuring Service Encounter Satisfaction with Customer Service Chatbots using Sentiment Analysis Self-Tracking and Gamification: Analyzing the Interplay of Motivations, Usage and Motivation Fulfillment Erfolgsfaktoren von Augmented-Reality-Applikationen: Analyse von Nutzerrezensionen mit dem Review-Mining-Verfahren Designing Dynamic Decision Support for Electronic Requirements Negotiations Who is Stressed by Using ICTs? A Qualitative Comparison Analysis with the Big Five Personality Traits to Understand Technostress Walking the Middle Path: How Medium Trade-Off Exposure Leads to Higher Consumer Satisfaction in Recommender Agents Theory-Based Affordances of Utilitarian, Hedonic and Dual-Purposed Technologies: A Literature Review Eliciting Customer Preferences for Shopping Companion Apps: A Service Quality Approach The Role of Early User Participation in Discovering Software – A Case Study from the Context of Smart Glasses The Fluidity of the Self-Concept as a Framework to Explain the Motivation to Play Video Games Heart over Heels? An Empirical Analysis of the Relationship between Emotions and Review Helpfulness for Experience and Credence Goods Track 11: Information Security and Information Privacy Unfolding Concerns about Augmented Reality Technologies: A Qualitative Analysis of User Perceptions To (Psychologically) Own Data is to Protect Data: How Psychological Ownership Determines Protective Behavior in a Work and Private Context Understanding Data Protection Regulations from a Data Management Perspective: A Capability-Based Approach to EU-GDPR On the Difficulties of Incentivizing Online Privacy through Transparency: A Qualitative Survey of the German Health Insurance Market What is Your Selfie Worth? A Field Study on Individuals’ Valuation of Personal Data Justification of Mass Surveillance: A Quantitative Study An Exploratory Study of Risk Perception for Data Disclosure to a Network of Firms Track 12: Umweltinformatik und nachhaltiges Wirtschaften Kommunikationsfäden im Nadelöhr – Fachliche Prozessmodellierung der Nachhaltigkeitskommunikation am Kapitalmarkt Potentiale und Herausforderungen der Materialflusskostenrechnung Computing Incentives for User-Based Relocation in Carsharing Sustainability’s Coming Home: Preliminary Design Principles for the Sustainable Smart District Substitution of hazardous chemical substances using Deep Learning and t-SNE A Hierarchy of DSMLs in Support of Product Life-Cycle Assessment A Survey of Smart Energy Services for Private Households Door-to-Door Mobility Integrators as Keystone Organizations of Smart Ecosystems: Resources and Value Co-Creation – A Literature Review Ein Entscheidungsunterstützungssystem zur ökonomischen Bewertung von Mieterstrom auf Basis der Clusteranalyse Discovering Blockchain for Sustainable Product-Service Systems to enhance the Circular Economy Digitale Rückverfolgbarkeit von Lebensmitteln: Eine verbraucherinformatische Studie Umweltbewusstsein durch audiovisuelles Content Marketing? Eine experimentelle Untersuchung zur Konsumentenbewertung nachhaltiger Smartphones Towards Predictive Energy Management in Information Systems: A Research Proposal A Web Browser-Based Application for Processing and Analyzing Material Flow Models using the MFCA Methodology Track 13: Digital Work - Social, mobile, smart On Conversational Agents in Information Systems Research: Analyzing the Past to Guide Future Work The Potential of Augmented Reality for Improving Occupational First Aid Prevent a Vicious Circle! The Role of Organizational IT-Capability in Attracting IT-affine Applicants Good, Bad, or Both? Conceptualization and Measurement of Ambivalent User Attitudes Towards AI A Case Study on Cross-Hierarchical Communication in Digital Work Environments ‘Show Me Your People Skills’ - Employing CEO Branding for Corporate Reputation Management in Social Media A Multiorganisational Study of the Drivers and Barriers of Enterprise Collaboration Systems-Enabled Change The More the Merrier? The Effect of Size of Core Team Subgroups on Success of Open Source Projects The Impact of Anthropomorphic and Functional Chatbot Design Features in Enterprise Collaboration Systems on User Acceptance Digital Feedback for Digital Work? Affordances and Constraints of a Feedback App at InsurCorp The Effect of Marker-less Augmented Reality on Task and Learning Performance Antecedents for Cyberloafing – A Literature Review Internal Crowd Work as a Source of Empowerment - An Empirical Analysis of the Perception of Employees in a Crowdtesting Project Track 14: Geschäftsmodelle und digitales Unternehmertum Dividing the ICO Jungle: Extracting and Evaluating Design Archetypes Capturing Value from Data: Exploring Factors Influencing Revenue Model Design for Data-Driven Services Understanding the Role of Data for Innovating Business Models: A System Dynamics Perspective Business Model Innovation and Stakeholder: Exploring Mechanisms and Outcomes of Value Creation and Destruction Business Models for Internet of Things Platforms: Empirical Development of a Taxonomy and Archetypes Revitalizing established Industrial Companies: State of the Art and Success Principles of Digital Corporate Incubators When 1+1 is Greater than 2: Concurrence of Additional Digital and Established Business Models within Companies Special Track 1: Student Track Investigating Personalized Price Discrimination of Textile-, Electronics- and General Stores in German Online Retail From Facets to a Universal Definition – An Analysis of IoT Usage in Retail Is the Technostress Creators Inventory Still an Up-To-Date Measurement Instrument? Results of a Large-Scale Interview Study Application of Media Synchronicity Theory to Creative Tasks in Virtual Teams Using the Example of Design Thinking TrustyTweet: An Indicator-based Browser-Plugin to Assist Users in Dealing with Fake News on Twitter Application of Process Mining Techniques to Support Maintenance-Related Objectives How Voice Can Change Customer Satisfaction: A Comparative Analysis between E-Commerce and Voice Commerce Business Process Compliance and Blockchain: How Does the Ethereum Blockchain Address Challenges of Business Process Compliance? Improving Business Model Configuration through a Question-based Approach The Influence of Situational Factors and Gamification on Intrinsic Motivation and Learning Evaluation von ITSM-Tools für Integration und Management von Cloud-Diensten am Beispiel von ServiceNow How Software Promotes the Integration of Sustainability in Business Process Management Criteria Catalog for Industrial IoT Platforms from the Perspective of the Machine Tool Industry Special Track 3: Demos & Prototyping Privacy-friendly User Location Tracking with Smart Devices: The BeaT Prototype Application-oriented robotics in nursing homes Augmented Reality for Set-up Processe Mixed Reality for supporting Remote-Meetings Gamification zur Motivationssteigerung von Werkern bei der Betriebsdatenerfassung Automatically Extracting and Analyzing Customer Needs from Twitter: A “Needmining” Prototype GaNEsHA: Opportunities for Sustainable Transportation in Smart Cities TUCANA: A platform for using local processing power of edge devices for building data-driven services Demonstrator zur Beschreibung und Visualisierung einer kritischen Infrastruktur Entwicklung einer alltagsnahen persuasiven App zur Bewegungsmotivation für ältere Nutzerinnen und Nutzer A browser-based modeling tool for studying the learning of conceptual modeling based on a multi-modal data collection approach Exergames & Dementia: An interactive System for People with Dementia and their Care-Network Workshops Workshop Ethics and Morality in Business Informatics (Workshop Ethik und Moral in der Wirtschaftsinformatik – EMoWI’19) Model-Based Compliance in Information Systems - Foundations, Case Description and Data Set of the MobIS-Challenge for Students and Doctoral Candidates Report of the Workshop on Concepts and Methods of Identifying Digital Potentials in Information Management Control of Systemic Risks in Global Networks - A Grand Challenge to Information Systems Research Die Mitarbeiter von morgen - Kompetenzen künftiger Mitarbeiter im Bereich Business Analytics Digitaler Konsum: Herausforderungen und Chancen der Verbraucherinformati

System design and patient positioning for dedicated breast computed tomography

Hintergrund und Ziele Brustkrebs ist die häufigste Krebserkrankung und -todesursache bei Frauen der westlichen Welt. Angesichts steigender Inzidenz, ist in Abwesenheit von adäquaten primären Präventionsmaßnahmen die Mammografie derzeit als einziges anerkanntes Verfahren in der Lage prognostisch günstige Vorformen des Mammakarzinoms im Rahmen flächendeckender Früherkennungsprogramme bei Frauen mit normalem Brustkrebsrisiko zu entdecken und die Mortalität zu senken. Jedoch unterliegt die Mammografie bekannten Nachteilen, wie Überlagerungseffekten, massiv reduzierter Sensitivität bei dichtem Brustgewebe und schmerzhafter Kompression. Die dedizierte CT der Brust scheint geeignet, diese Probleme zu überwinden, blieb allerdings bisher den Beweis adäquater Bildqualität insbesondere für den Nachweis präinvasiver Frühformen schuldig. Ein am Institut für Medizinische Physik verfolgtes, neuartiges Konzept weist in Simulationen und Experimenten erstmals die geforderten Leistungswerte auf. Kritisch und stets in Frage gestellt bei Entwicklungsbestrebungen zur Brust-CT ist hierbei die Darstellung des brustwandnahen Anteils der Brust und des axillären Ausläufers als mögliche Primärmanifestation von Metastasen. Das Ziel dieser Arbeit besteht in der Erarbeitung eines Gestaltungsentwurfs für dieses neuartige Brust-CT-System. Dabei gilt es die Vorgaben aus den Simulationen zu übertragen und einzubeziehen, sowie die ungeklärten Problemstellungen zu lösen. Nach Gestaltung des Bildgebungssystems liegt der Schwerpunkt auf der Neuentwicklung eines Lagerungssystems bestehend aus Patientenliege und Brustimmobilisierung. Auf Basis theoretischer Überlegungen sollen Probandenstudien an Versuchsmodellen entscheidende Impulse liefern. Methoden Nach Präzisierung der relevanten Anforderungen wurden zwei Alternativen zur anordnungsbestimmenden Gestaltung des Bildgebungssystems erstellt und bewertet. Die kritischen Parameter der Patientenlagerung wurden identifiziert und mögliche Gestaltungsvarianten des Lagerungssystems in einem Versuchsmodell realisiert. Anhand mittels MRT gewonnener Schichtbilder wurde an 25 Probandinnen die Wirksamkeit sowie der Einfluss verschiedener Lagerungsparameter überprüft; zudem wurden der Komfort beurteilt und eventuelle Schmerzpunkte identifiziert. Für die Brust-CT neuartig, wurde ein Konzept zur Brustimmobilisierung durch Unterdruck entwickelt, und der Nachweis der Konzepttauglichkeit in zwei Studien – eine am Versuchsmodell der Lagerung, eine an einem Stereotaxietisch – an insgesamt 49 Probandinnen erbracht. Neben der Funktion wurden Komfort und Akzeptanz des Systems für sich und im Vergleich zur Mammografie evaluiert und die Ergebnisse in Gestaltungsvorgaben umgesetzt. Die Auswertung erfolgte einerseits auf Basis von MRT-Daten und andererseits anhand von Fotografien. Ergebnisse Das favorisierte Anordnungskonzept zeichnet sich neben der höheren und ausgeglicheneren Gesamtbewertung durch eine hohe zu erwartende Systemgenauigkeit, eine gute Zugänglichkeit zur Brust und eine leistungsfähige und kostengünstige Drehübertragung aus. Durch die spezielle Liegengestaltung konnte signifikant mehr brustwandnahes Brustgewebe in das Messfeld verlagert werden. Sowohl eine Absenkung der Liegenfläche als auch eine Vergrößerung des Öffnungsdurchmessers erwiesen sich als vorteilhaft. Eine Rotation des Körpers entlang der Längsachse hatte keinen signifikanten Effekt. Der Lagerungskomfort konnte durch Absenkung der Liegenfläche verbessert werden. Hier zeigte sich die Körperrotation sogar nachteilig. Das verwendete Versuchsmodell zur Unterdruckbrustimmobilisierung stellte sich in 85 Prozent der Fälle als zuverlässig heraus. Fehlerquellen wurden identifiziert und Gestaltungsverbesserungen erarbeitet. Durch Einsatz des Immobilisierungssystems konnte eine signifikante Verlagerung weiteren posterioren Brustgewebes in das Messfeld erreicht werden. 94 Prozent der Probandinnen würden die Unterdruckbrustimmobilisierung der Kompression bei der Mammografie vorziehen. Schlussfolgerungen Die durchgeführten Untersuchungen dokumentieren, dass bei Gestaltung nach den erarbeiteten Vorgaben, die in der Simulation ermittelte Bildqualität in einem dedizierten Brust-CT-System an die klinischen Anforderungen adaptiert werden kann. Bei entsprechender Formung der Liege ist eine Darstellung der Brust inklusive des posterioren Aspekts bis hin zur Brustwand möglich. Durch Einsatz einer Unterdruckbrustimmobilisierungsvorrichtung kann die Abdeckung der Brust noch weiter verbessert werden. Mit angepasster Formgestaltung ist die Erfassung des zum Primärstaging wichtigen axillären Ausläufers denkbar. Angesichts der positiven, den Komfort betreffenden Untersuchungsergebnisse ist eine hohe Patientenakzeptanz der dedizierten Brust-CT zu erwarten.Aims Breast cancer is the most common cancer and number one cause for cancer related deaths among women in the western hemisphere. Facing growing incidence and in absence of adequate primary prevention, mammography currently is the only technique capable of detecting preinvasive cancers associated with a favorable prognosis within a screening program of women at average risk for breast cancer and reducing mortality. However, mammography subjects several well known drawbacks like superimposition effects, massively limited sensitivity in dense breast tissue and painful breast compression. Dedicated breast CT might potentially overcome theses problems, but has not yet proven to provide adequate image quality especially for the detection of preinvasive early stage breast cancer. For the first time, a new approach followed by the Institute of Medical Physics, shows the demanded performance in simulation studies and experiments. Crucial and always questioned concerning development attempts at breast CT is the coverage of the breast tissue near the chest wall and the axillary tail as the first site of metastasis. The aim of our work was the design realization of this novel breast CT system. Therefore the requirements derived from the simulations have to be transferred and included as well as the remaining open issues have to be solved. After structuring the imaging system the development was focussed on a patient positioning system consisting of patient table and breast immobilization device. On the basis of theoretic considerations volunteer studies using prototypes should deliver key impulses. Materials and Methods After specifiing the relevant requirements two alternative drafts for the layout structure of the imaging system were created and evaluated. Critical parameters of the patient position were identified and a mockup of the patient positioning system mimicking potential design variants was realized. Effectiveness and influence of each single parameter were determined using MRI in a 25 volunteer study. Futhermore patient comfort was assessed and areas of discomfort were identified. Novel to breast CT, a concept for immobilizing the breast using depression was developed and the feasibility proved in two volunteer studies (one using the mockup of the positioning system and one at a biopsy table) comprising a total of 49 volunteers. Besides effectiveness, both comfort and acceptance were evaluated independently and in comparison to mammography. The results were adapted in design guidelines. Analyses were conducted using both MRI data and photographs. Results The preferred layout concept features besides a higher and more balanced overall score, an expected high system accuracy, a broad access to the breast and a comprehensive and cost-efficient rotation transmission. Dedicated table design shifted significantly more breast tissue near the chest wall into the field of measurement. Both lowering the table surface and increasing the opening diameter proved to be beneficial. The rotation to a side prone position had no significant effect. Patient comfort could be improved by lowering the table surface. Here body rotation turned out to be adverse. The prototype used for breast immobilization by depression worked reliably in 85 percent of the cases. Sources of defects were identified and design improvements prepared. Using the immobilization device a significant shift of further posterior breast tissue into the field of measurement was achieved. 94 percent of the study volunteers would prefer the depression immobilization to the compression used for mammography. Conclusions The studies document that the image quality determined in simulation studies can be adapted to a dedicated breast CT under clinical circumstances when applying the developed design concept. A table shape according to the guidelines enables for imaging the breast including the most posterior aspect. Using the depression immobilization device the coverage of the breast can be further improved. Thank to refinements in shape including the axillary tail important for primary staging seems possible. Given the positive results concerning patient comfort a high patient acceptance of dedicated breast CT can be anticipated

Transformation of Riccia fluitans, an Amphibious Liverwort Dynamically Responding to Environmental Changes

The colonization of land by streptophyte algae, ancestors of embryophyte plants, was a fundamental event in the history of life on earth. Bryophytes are early diversifying land plants that mark the transition from freshwater to terrestrial ecosystems. The amphibious liverwort Riccia fluitans can thrive in aquatic and terrestrial environments and thus represents an ideal organism to investigate this major transition. Therefore, we aimed to establish a transformation protocol for R. fluitans to make it amenable for genetic analyses. An Agrobacterium transformation procedure using R. fluitans callus tissue allows to generate stably transformed plants within 10 weeks. Furthermore, for comprehensive studies spanning all life stages, we demonstrate that the switch from vegetative to reproductive development can be induced by both flooding and poor nutrient availability. Interestingly, a single R. fluitans plant can consecutively adapt to different growth environments and forms distinctive and reversible features of the thallus, photosynthetically active tissue that is thus functionally similar to leaves of vascular plants. The morphological plasticity affecting vegetative growth, air pore formation, and rhizoid development realized by one genotype in response to two different environments makes R. fluitans ideal to study the adaptive molecular mechanisms enabling the colonialization of land by aquatic plants