Image Formation in Electron Microscopes at Low Energies

In the past, the spatial resolution in electron microscopy was mainly limited by the unavoidable aberrations of round electron lenses. Nowadays, the successful realization of aberration correction allows achieving atomic resolution for electron energies as low as 20 keV. In this energy range, existing models for the image formation process must be augmented by previously neglected effects, since the commonly used paraxial approximation breaks down. Starting from quantum mechanical principles, this work will show that electron microscopic image contrast from elastic scattering can be calculated by solving a series of eigenvalue problems. Thereby, new theoretical insights into the scattering process are gained. Furthermore, the derived analytical matrix equations turn out to be suited for numerical calculations as well. Through the inclusion of backscattering effects, a unified description of the image formation process in different types of electron microscopes is obtained. Thus, for the first time, the elastic scattering channel in a scanning electron microscope (SEM) can be simulated based on the wave-mechanical description of the electron. Moreover, this work will show that the direct quadrature of the Schrödinger equation can be used to simulate electron micrographs. With the help of these new scattering solutions, the validity of the paraxial approximation is investigated in detail

Supply management and procurement at a South African FMCG company : a practical example of developing a decision support tool for managing direct material cost

Thesis (MComm)—Stellenbosch University, 2016.ENGLISH ABSTRACT: One of the functions within the supply chain of manufacturing companies is the procurement of direct materials that are needed for the production of products sold to consumers. Even though the process of purchasing materials was always required within the manufacturing process, it only recently gained attention on management level. Today, organisations set up centralised procurement functions that develop global sourcing strategies in order to align procurement processes, people and technology. The goal is to reduce total cost while maintaining high quality, availability and service levels. However, procurement functions are challenged by a number of risks during its global sourcing activities that can have major impacts on direct material cost. Johnson & Johnson is a major global player within the Fast Moving Consumer Goods (FMCG) industry and acknowledged a significant sense of uncertainty relating to the identification and measurement of direct material cost drivers within their global procurement function. Even though Johnson & Johnson is aware that the economic environment has an impact on its procurement spend, it has a limited ability to measure and quantify these effects. Based on the case of Johnson & Johnson, this study’s objective was to develop a decision support tool that measures and analyses the impact of cost drivers on direct material cost. The aim was to develop a model that can be used by procurement professionals in industry in order to provide insight into the procurement cost structure and to identify opportunities that can lead to risk and cost reduction. A case study research design was followed, which included secondary and primary research to collect qualitative and quantitative data. The research methods included observations and input discussions at the company, as well as a comprehensive model development process, which was used in order to create the decision support tool. As the decision support tool was developed on the case of Johnson & Johnson, data were collected from the company in order to test the model and generate outputs. Following the individual process steps of the development process resulted in a highly structured and documented approach to develop the decision support tool. Two major cost drivers of procurement spend when conducting global sourcing were identified: fluctuating exchange rates and volatile commodity markets. Both of these cost drivers were analysed and included during the decision-support tool development process. As a result, a decision support tool is presented that provides functionality to measure the exposure and the potential impact value of the first-tier currency impact, second-tier currency impact as well as the inflation impact. Furthermore, “what-if” and scenario analyses provide a predictive view based on actual forecasts. As an additional output, the decision support tool provides detailed insight and transparency of the total procurement spend, providing important information for decision makers.AFRIKAANSE OPSOMMING: Een van die funksies in die voorsieningsketting van vervaardigingsmaatskappye is die verkryging van direkte materiaal wat benodig word vir die vervaardiging van produkte wat aan verbruikers verkoop word. Hoewel die proses van materiaalaankope nog altyd binne die vervaardigingsproses nodig was, het dit eers onlangs op bestuursvlak aandag getrek. Vandag stel organisasies gesentraliseerde verkrygingsfunksies saam wat globale strategieë ontwikkel vir die verkryging van hulpbronne om sodoende verkrygingsprosesse, mense en tegnologie met mekaar in ooreenstemming te bring. Die doel is om totale koste te verminder terwyl hoë gehalte, beskikbaarheid en diensvlakke gehandhaaf word. Tydens die globale verkrygingsaktiwiteite word daardie funksies egter deur ’n aantal risiko-uitdagings in die gesig gestaar wat ’n groot impak op direkte materiaalkoste kan hê. Johnson & Johnson is ’n vername wêreldspeler binne die industrie vir vinnig bewegende verbruikersgoedere (VBVG) en herken ’n beduidende gevoel van onsekerheid wat verband hou met die identifisering en meting van direkte materiaalkostedrywers binne hulle globale verkrygingsfunksie. Hoewel Johnson & Johnson daarvan bewus is dat die ekonomiese omgewing ’n impak op hulle verkrygingsbesteding het, beskik hulle oor beperkte vermoë om hierdie effekte te meet en te kwantifiseer. Gegrond op die geval van Johnson & Johnson, was hierdie studie se doelwit om ’n besluitsteunhulpmiddel te ontwikkel vir die identifisering en meting van direkte materiaalkostedrywers. Die oorhoofse doel was om ’n model te ontwikkel wat deur verkrygingsberoepslui in die bedryf gebruik kan word om insig in die verkrygingkostestruktuur te voorsien, en om geleenthede te identifiseer wat na risiko en kostevermindering kan lei. ’n Gevallestudienavorsingsontwerp is gevolg wat primêre en sekondêre navorsing ingesluit het vir die versameling van kwalitatiewe en kwantitatiewe data. Die navorsingsmetodes het waarnemings en besprekings by die maatskappy sowel as die omvattende modelontwikkelingsproses ingesluit om hierdie besluitsteunhulpmiddel te skep. Aangesien die besluitsteunhulpmiddel op die geval van Johnson & Johnson berus, is data van die maatskappy versamel om sodoende die model te toets, en uitset te genereer. Die volg van die individuele stappe van die ontwikkelingsproses het gelei tot ’n hoogs gestruktureerde en gedokumenteerde benadering in die ontwikkeling van die besluitsteunhulpmiddel. Twee belangrike kostedrywers van verkrygingbesteding in die uitvoer van globale verkryging is geïdentifiseer: wisselkoersfluktuering en onbestendige kommoditeitsmarkte. Albei hierdie kostedrywers is ontleed en ingesluit tydens die ontwikkelingsproses van die besluitsteunhulpmiddel. Gevolglik word ’n besluitsteunhulpmiddel gebied wat funksionaliteit verskaf om die blootstelling en potensiële impakwaarde van die eerstevlakvaluta-impak, tweedevlakvaluta-impak, sowel as die inflasie-impak te meet. Verder verskaf “wat as”- en scenario-ontledings voorspellende beskouings wat op werklike vooruitskattings gegrond is. As bykomende uitset verskaf die besluitsteunhulpmiddel gedetailleerde insig en deursigtigheid van die totale verkrygingbesteding, en verskaf sodoende belangrike inligting vir besluitnemers

Diagnostic Confidence of Run-Off CT-Angiography as the Primary Diagnostic Imaging Modality in Patients Presenting with Acute or Chronic Peripheral Arterial Disease

Objectives To investigate the reliability of CT-angiography of the lower extremities (run-off CTA) to derive a treatment decision in patients with acute and chronic peripheral artery disease (PAD). Materials and Methods 314 patients referred for run-off CTA were includ-ed in this retrospective study. First, diagnostic confidence of run-off CTA to derive a treat-ment decision was assessed in an interdisciplinary vascular conference using a 2 point scale (sufficient or not sufficient diagnostic confidence) and compared with the image quality eval-uated by two readers in consensus in four different levels (abdominopelvic, thigh, calf, foot arteries). Second, reliability of treatment decision was verified in all patients undergoing re-vascularization therapy. Results Diagnostic confidence of run-off CTA to derive a treatment deci-sion was sufficient in all patients with acute and in 97% of patients (215/221) with chronic PAD, whereas the rate of run-off CTA with non-diagnostic image quality was considerably higher in the calf and foot level (acute vs. chronic; calf: 28% vs.17%; foot: 52% vs. 20%). Reliability of treatment decision was superior for patients with chronic (123/133 = 92%) than for patients with acute PAD (64/78 = 82%, P = 0.02). Conclusion Run-off CTA is a reliable imaging modality for primary diag-nostic work-up of patients with acute and chronic PAD

A non-standard finite-difference-method for a non-autonomous epidemiological model: analysis, parameter identification and applications

In this work, we propose a new non-standard finite-difference-method for the numerical solution of the time-continuous non-autonomous susceptible-infected-recovered model. For our time-discrete numerical solution algorithm, we prove preservation of non-negativity and show that the unique time-discrete solution converges linearly towards the time-continuous unique solution. In addition to that, we introduce a parameter identification algorithm for the susceptible-infected-recovered model. Finally, we provide two numerical examples to stress our theoretical findings

Geometry and Distortion Prediction of Multiple Layers for Wire Arc Additive Manufacturing with Artificial Neural Networks

Wire arc additive manufacturing (WAAM) is a direct energy deposition (DED) process with high deposition rates, but deformation and distortion can occur due to the high energy input and resulting strains. Despite great efforts, the prediction of distortion and resulting geometry in additive manufacturing processes using WAAM remains challenging. In this work, an artificial neural network (ANN) is established to predict welding distortion and geometric accuracy for multilayer WAAM structures. For demonstration purposes, the ANN creation process is presented on a smaller scale for multilayer beads on plate welds on a thin substrate sheet. Multiple concepts for the creation of ANNs and the handling of outliers are developed, implemented, and compared. Good results have been achieved by applying an enhanced ANN using deformation and geometry from the previously deposited layer. With further adaptions to this method, a prediction of additive welded structures, geometries, and shapes in defined segments is conceivable, which would enable a multitude of applications for ANNs in the WAAM-Process, especially for applications closer to industrial use cases. It would be feasible to use them as preparatory measures for multi-segmented structures as well as an application during the welding process to continuously adapt parameters for a higher resulting component quality

Asiatische Großmächte: China, Indien und Japan als Akteure regionaler und internationaler Ordnungspolitik

"China, Indien und Japan sind zentrale Partner Deutschlands und der EU in Asien, von denen erwartet wird, dass sie mehr internationale Verantwortung übernehmen. Die wachsende weltwirtschaftliche Bedeutung der drei Staaten wirft die Frage auf, ob und inwieweit sie neue internationale Ordnungsvorstellungen entwickeln. Inwieweit stimmen ihre außenpolitischen Ideen mit der bestehenden internationalen Ordnung überein oder inwieweit entwickeln sie eigene regionale und globale Ordnungsvorstellungen, die sich als Alternative oder Gegenentwurf zu bestehenden Institutionen deuten lassen? Vieles spricht dafür, dass das 21. Jahrhundert eher wirtschaftlich als politisch von den drei asiatischen Staaten geprägt sein wird. Während es in China Ansätze zu eigenen regionalen und internationalen Ordnungsvorstellungen gibt, zeichnet sich in Indien und Japan eine Debatte dazu bislang kaum ab. Dennoch wird globales Regieren schwieriger, denn die Staaten werden angesichts unterschiedlicher innenpolitischer Herausforderungen ihre eigenen Interessen verstärkt in internationalen Verhandlungsregimen zur Geltung bringen." (Autorenreferat

Lung tumour growth kinetics in SPC-c-Raf-1-BB transgenic mice assessed by longitudinal in-vivo micro-CT quantification

<p>Abstract</p> <p>Background</p> <p>SPC-c-Raf-1-BxB transgenic mice develop genetically induced disseminated lung adenocarcinoma allowing examination of carcinogenesis and evaluation of novel treatment strategies. We report on assessment of lung tumour growth kinetics using a semiautomated region growing segmentation algorithm.</p> <p>Methods</p> <p>156 non contrast-enhanced respiratory gated micro-CT of the lungs were obtained in 12 SPC-raf transgenic (n = 9) and normal (n = 3) mice at different time points. Region-growing segmentation of the aerated lung areas was obtained as an inverse surrogate for tumour burden. Time course of segmentation volumes was assessed to demonstrate the potential of the method for follow-up studies.</p> <p>Results</p> <p>Micro-CT allowed assessment of tumour growth kinetics and semiautomated region growing enabled quantitative analysis. Significant changes of the segmented lung volumes over time could be shown (<it>p </it>= 0.009). Significant group differences could be detected between transgenic and normal animals for time points 8 to 13 months (<it>p </it>= 0.043), when marked tumour progression occurred.</p> <p>Conclusion</p> <p>The presented region-growing segmentation algorithm allows in-vivo quantification of multifocal lung adenocarcinoma in SPC-raf transgenic mice. This enables the assessment of tumour load and progress for the study of carcinogenesis and the evaluation of novel treatment strategies.</p