Erfolgsfaktoren bei der Implementierung von E-Government-Lösungen mit dem Schwerpunkt G2B-Anwendungen

E-Business im Generellen und E-Government im Speziellen haben in den letzten Jahren immer mehr an Bedeutung gewonnen. Die Transformation der Verwaltungsprozesse auf elektronische Medien birgt eine Vielzahl von Potentialen für alle Beteiligten: Einrichtungen der öffentlichen Verwaltung, Bürger und Unternehmen. Dennoch ist es in den letzten Jahren bei solchen Projekten, insbesondere im A2B-Bereich, also der Kommunikation zwischen Verwaltung und Unternehmen, immer wieder zu Problemen gekommen. Das Ziel der Arbeit ist es deshalb die Erfolgsfaktoren von solchen E-Government-Projekten zu identifizieren. Hierzu werden zunächst die Grundlagen des E-Business erläutert und die Begrifflichkeiten voneinander abgegrenzt. Insbesondere werden die verschiedenen Kategorien von beteiligten Akteuren, die generischen Ziele des E-Business und dessen Einflussfaktoren genannt, um so den Bezugsrahmen des E-Business zu definieren. Darauf aufbauend werden die Anwendungsbereiche des E-Governments erläutert und die funktionale und strukturelle Unterscheidung der möglichen Szenarien dargestellt. Im Hauptteil der Arbeit werden anschließend anhand von Literatur-Quellen und aktuellen Studien die sechs Erfolgsfaktoren analysiert, die sich bei der Implementierung von E-Government-Lösungen in der Vergangenheit gezeigt haben. Diese reichen von technischen Faktoren wie der Kompatibilität der Systeme und der Datensicherheit über den richtigen Umgang von Veränderungen mit Hilfe des Change Managements bis hin zu den unterschiedlichen Rollen der beteiligten Akteure. In den folgenden Abschnitten werden einige Aspekte des E-Governments genauer fokussiert: die verschiedenen Architekturen und Standards, relevante Gesetze und die deutsche E-Government-Strategie sowie der internationale Vergleich von Deutschland im E-Government-Bereich. Dabei wird geprüft, welchen Einfluss diese Aspekte auf die identifizierten Erfolgsfaktoren haben. Bevor das Fazit die gewonnenen Erkenntnisse zusammen fasst und eine Prognose des E-Governments in Deutschland gibt, werden die beiden Verfahren ELSTER als positives und ELENA als negatives Beispiel für E-Government-Projekte im A2B-Bereich vorgestellt

Age-Dependent Patient and Trauma Characteristics and Hospital Resource Requirements-Can Improvement Be Made? An Analysis from the German Trauma Registry

Background and objectives: The burden of geriatric trauma patients continues to rise in Western society. Injury patterns and outcomes differ from those seen in younger adults. Getting a better understanding of these differences helps medical staff to provide a better care for the elderly. The aim of this study was to determine epidemiological differences between geriatric trauma patients and their younger counterparts. To do so, we used data of polytraumatized patients from the TraumaRegister DGU$^{®}$. Materials and Methods: All adult patients that were admitted between 1 January 2013 and 31 December 2017 were included from the TraumaRegister DGU$^{®}$. Patients aged 55 and above were defined as the elderly patient group. Patients aged 18-54 were included as control group. Patient and trauma characteristics, as well as treatment and outcome were compared between groups. Results: A total of 114,169 severely injured trauma patients were included, of whom 55,404 were considered as elderly patients and 58,765 younger patients were selected for group 2. Older patients were more likely to be admitted to a Level II or III trauma center. Older age was associated with a higher occurrence of low energy trauma and isolated traumatic brain injury. More restricted utilization of CT-imaging at admission was observed in older patients. While the mean Injury Severity Score (ISS) throughout the age groups stayed consistent, mortality rates increased with age: the overall mortality in young trauma patients was 7.0%, and a mortality rate of 40.2% was found in patients >90 years of age. Conclusions: This study shows that geriatric trauma patients are more frequently injured due to low energy trauma, and more often diagnosed with isolated craniocerebral injuries than younger patients. Furthermore, utilization of diagnostic tools as well as outcome differ between both groups. Given the aging society in Western Europe, upcoming studies should focus on the right application of resources and optimizing trauma care for the geriatric trauma patient

The number of beds occupied is an independent risk factor for discharge of trauma patients

Reducing the burden of limited capacity on medical practitioners and public health systems requires a time-dependent characterization of hospitalization rates, such that inferences can be drawn about the underlying causes for hospitalization and patient discharge. The aim of this study was to analyze non-medical risk factors that lead to the discharge of trauma patients. This retrospective cohort study includes trauma patients who were treated in Switzerland between 2011 and 2018. The national Swiss database for quality assurance in surgery (AQC) was reviewed for trauma diagnoses according to the ICD-10 code. Non-medical risk factors include seasonal changes, daily changes, holidays, and number of beds occupied by trauma patients across Switzerland. Individual patient information was aggregated into counts per day of total patients, as well as counts per day of levels of each categorical variable of interest. The ARIMA-modeling was utilized to model the number of discharges per day as a function of auto aggressive function of all previously mentioned risk factors. This study includes 226,708 patients, 118,059 male (age 48.18, standard deviation (SD) 22.34 years) and 108,649 female (age 62.57, SD 22.89 years) trauma patients. The mean length of stay was 7.16 (SD 14.84) days and most patients were discharged home (n = 168,582, 74.8%). A weekly and yearly seasonality trend can be observed in admission trends. The mean number of occupied trauma beds ranges from 3700 to 4000 per day. The number of occupied beds increases on weekdays and decreases on holidays. The number of occupied beds is a positive, independent risk factor for discharge in trauma patients; as the number of occupied beds increases at any given time, so does the risk for discharge. The number of beds occupied represents an independent non-medical risk factor for discharge. Capacity determines triage of hospitalized patients and therefore might increase the risk of premature discharge

Resource-aware Research on Universe and Matter: Call-to-Action in Digital Transformation

Given the urgency to reduce fossil fuel energy production to make climate tipping points less likely, we call for resource-aware knowledge gain in the research areas on Universe and Matter with emphasis on the digital transformation. A portfolio of measures is described in detail and then summarized according to the timescales required for their implementation. The measures will both contribute to sustainable research and accelerate scientific progress through increased awareness of resource usage. This work is based on a three-days workshop on sustainability in digital transformation held in May 2023.Comment: 20 pages, 2 figures, publication following workshop 'Sustainability in the Digital Transformation of Basic Research on Universe & Matter', 30 May to 2 June 2023, Meinerzhagen, Germany, https://indico.desy.de/event/3748

Ungrazed salt marsh has well connected soil pores and less dense sediment compared with grazed salt marsh: a CT scanning study

Salt marshes provide various ecosystem functions and services including flooding protection, wildlife habitats, and carbon storage. These functions and services could, however, be strongly impacted by anthropogenic activities such as livestock grazing – a common practice in the Wadden Sea salt marshes located in North west of Europe. To assess the impact of grazing on soil parameters, a total number of eight soil cores (⌀: 18 cm; L: 50 cm) were collected in areas with and without livestock grazing, and scanned using a Computed Tomography (CT) to characterize soil parameters including soil macroporosity, sediment density, and pores connectivity. Subsequently, sub-samples were taken for determination of soil moisture content (%) and bulk density (g cm −3). To account for the impact of grazing on soil drainage after tidal inundations, water table relative to soil surface was monitored during two flooding events. Our results demonstrated that grazed salt marsh has higher top-soil bulk density, and lower macroporosity and pore connectivity, than ungrazed marsh, due to soil compaction by livestock grazing. Moreover, grazed marsh has slower water drainage and that might keep the soil waterlogged for a longer period of time which has implications on lowering decomposition rate due to lower soil redox. This study provides evidence that grazing alters physical soil parameters in salt marsh. Consequently, grazing needs to be accounted for when evaluating how land use impacts ecosystem services and functions including carbon sequestration

The evolution of the plastid chromosome in land plants: gene content, gene order, gene function

This review bridges functional and evolutionary aspects of plastid chromosome architecture in land plants and their putative ancestors. We provide an overview on the structure and composition of the plastid genome of land plants as well as the functions of its genes in an explicit phylogenetic and evolutionary context. We will discuss the architecture of land plant plastid chromosomes, including gene content and synteny across land plants. Moreover, we will explore the functions and roles of plastid encoded genes in metabolism and their evolutionary importance regarding gene retention and conservation. We suggest that the slow mode at which the plastome typically evolves is likely to be influenced by a combination of different molecular mechanisms. These include the organization of plastid genes in operons, the usually uniparental mode of plastid inheritance, the activity of highly effective repair mechanisms as well as the rarity of plastid fusion. Nevertheless, structurally rearranged plastomes can be found in several unrelated lineages (e.g. ferns, Pinaceae, multiple angiosperm families). Rearrangements and gene losses seem to correlate with an unusual mode of plastid transmission, abundance of repeats, or a heterotrophic lifestyle (parasites or myco-heterotrophs). While only a few functional gene gains and more frequent gene losses have been inferred for land plants, the plastid Ndh complex is one example of multiple independent gene losses and will be discussed in detail. Patterns of ndh-gene loss and functional analyses indicate that these losses are usually found in plant groups with a certain degree of heterotrophy, might rendering plastid encoded Ndh1 subunits dispensable

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

The multi-spectral signal properties of multiple reference optical coherence tomography

Efforts to reduce the size and costs of optical coherence tomography systems (OCT) for consumer applications, in general, focus on Fourier-domain OCT, due to its potential to be integrated on an optical chip, implementing the interferometer and the spectrometer together as a compact system. An alternative and near-term solution is multiple reference OCT. This technique utilizes a partial mirror in the reference arm to enhance the axial imaging depth of traditional time-domain OCT. The motivation of this thesis is to investigate the performance and sensitivity characteristics of multiple reference OCT in comparison to time-domain OCT. Due to the partial mirror, the light is recirculated multiple times and generates additional reference wavefronts reflected on the reference mirror with increasing path delays. A fascinating consequence of this is the frequency-dependence of each reflection, which draws parallels with Fourier-domain OCT. Hence, the spectral properties of the interference signals are studied in more detail. This thesis guides the reader towards the subject of OCT covering the fundamentals of OCT and the theoretical basis of multiple reference OCT. The spectral properties of the interference signals of MR-OCT are further explained, and it is shown that the increasing path delay in the reference arm of the Michelson interferometer causes an increase of the frequency similar to the increasing frequency vs. depth in the sample for Fourier-domain OCT. The spacing between the partial mirror and the scanning mirror, in conjunction with the scanning range and velocity, play a unique role in controlling a variety of parameters, which are not available in any other OCT system. Signal simulations are provided for some theoretical aspects of interest and compared with signals measured on a sample mirror. For each of the multiple interference signals, the sensitivity was measured, and the results are compared to conventional time-domain OCT. The higher orders of reflections show some non-linear characteristics that may reduce dynamic range and sensitivity. Zemax was used to simulate the beam propagation in the optical system. The impact of the reference mirror scanning parameters on the overall system characteristics was examined. Further, a novel en-face scanning modality is described that can increase the data acquisition speed due to the reduction of the width of the scanned depth layers and demonstrates the flexibility of the scanning protocol of MR-OCT that would otherwise require extensive efforts with other OCT systems. Some more specific aspects of the signal and image processing are discussed that have relevance for the image reconstruction of the multiple signal segments originating from the recirculated light due to the partial mirror in the reference arm. So far the results in this thesis have shown that the multiple interference frequencies originate from an actual change of the source spectrum due to the Doppler effect caused by the scanning mirror. Under certain conditions, it is possible that multiple reference waves create phantom signals. So far the phantom signals are difficult to observe and may not be of significant concern for conventional imaging applications with MR-OCT. The increasing axial scanning range causes depth regions to be scanned multiple times, and averaging can improve somewhat the SNR. Whereas, the time delay between the multiple scanned regions has a delay of a few hundred femtoseconds which may open new application areas that require high-speed scanning

The multi-spectral signal properties of multiple reference optical coherence tomography

Efforts to reduce the size and costs of optical coherence tomography systems (OCT) for consumer applications, in general, focus on Fourier-domain OCT, due to its potential to be integrated on an optical chip, implementing the interferometer and the spectrometer together as a compact system. An alternative and near-term solution is multiple reference OCT. This technique utilizes a partial mirror in the reference arm to enhance the axial imaging depth of traditional time-domain OCT. The motivation of this thesis is to investigate the performance and sensitivity characteristics of multiple reference OCT in comparison to time-domain OCT. Due to the partial mirror, the light is recirculated multiple times and generates additional reference wavefronts reflected on the reference mirror with increasing path delays. A fascinating consequence of this is the frequency-dependence of each reflection, which draws parallels with Fourier-domain OCT. Hence, the spectral properties of the interference signals are studied in more detail. This thesis guides the reader towards the subject of OCT covering the fundamentals of OCT and the theoretical basis of multiple reference OCT. The spectral properties of the interference signals of MR-OCT are further explained, and it is shown that the increasing path delay in the reference arm of the Michelson interferometer causes an increase of the frequency similar to the increasing frequency vs. depth in the sample for Fourier-domain OCT. The spacing between the partial mirror and the scanning mirror, in conjunction with the scanning range and velocity, play a unique role in controlling a variety of parameters, which are not available in any other OCT system. Signal simulations are provided for some theoretical aspects of interest and compared with signals measured on a sample mirror. For each of the multiple interference signals, the sensitivity was measured, and the results are compared to conventional time-domain OCT. The higher orders of reflections show some non-linear characteristics that may reduce dynamic range and sensitivity. Zemax was used to simulate the beam propagation in the optical system. The impact of the reference mirror scanning parameters on the overall system characteristics was examined. Further, a novel en-face scanning modality is described that can increase the data acquisition speed due to the reduction of the width of the scanned depth layers and demonstrates the flexibility of the scanning protocol of MR-OCT that would otherwise require extensive efforts with other OCT systems. Some more specific aspects of the signal and image processing are discussed that have relevance for the image reconstruction of the multiple signal segments originating from the recirculated light due to the partial mirror in the reference arm. So far the results in this thesis have shown that the multiple interference frequencies originate from an actual change of the source spectrum due to the Doppler effect caused by the scanning mirror. Under certain conditions, it is possible that multiple reference waves create phantom signals. So far the phantom signals are difficult to observe and may not be of significant concern for conventional imaging applications with MR-OCT. The increasing axial scanning range causes depth regions to be scanned multiple times, and averaging can improve somewhat the SNR. Whereas, the time delay between the multiple scanned regions has a delay of a few hundred femtoseconds which may open new application areas that require high-speed scanning