Backscattered Electron Imaging Using Single Crystal Scintillator Detectors

The image obtained by the detection of backscattered electrons (BSE) becomes an indispensable complement to the correct interpretation and more precise reconstruction of the surface of the specimen and its material composition. The BSE are carriers of information which is dependent on their angular and energy distribution. The choice of a certain type of BSE and their efficient detection make it possible to record the desired information with a different grade of quality. The knowledge of the angular and energy distribution of BSE is necessary for the adjustment of the correct position of the BSE detector with regard to the specimen and for its optimum geometrical configuration. The directional detection of a limited number of the BSE selected according to their angle and energy makes high demands on the efficiency of the detector. The paper presents BSE detectors based on single crystal aluminium oxides of YAG and YAP. Their spectral characteristics, time characteristics, detection quantum efficiency, electron resistance and mechanical, temperature and vacuum properties satisfy all demands of electron microscopy. The number of differently modified BSE detectors with single crystal scintillators allow application of various detection techniques, recording of different contrast mechanisms, combination of different detection modes (simultaneous detection), achievement of a high resolution of the BSE image. The paper reviews some 180 published papers by other authors. Their findings and the present author\u27s experimental results have formed the basis for backscattered electron imaging using single crystal scintillator detectors

Bringing self-initiated expatriates and companies together

The purpose of this study is to examine how, if at all, firms use what has been discovered about the motivations of self-initiated expatriates (SIEs) to attract, hire, develop and retain highvalue individuals from foreign countries. In order to do this, multiple research goals and hypotheses were formulated through a literature review. These cover the main motivations of SIEs to expatriate; which of these motivations companies are interested in; what SIE programs and policies companies have; to what extent these motives are integrated into the strategies; and how human resource professionals critically evaluate these. Then interviews were conducted with eleven organizations based primarily in Germany, with a focus on answering these questions. With these findings, it was possible to verify whether the research questions and therefore hypotheses were supported or not. I conclude that Human Resource Management (HRM) professionals can identify some (but not all) motivations of SIEs, that there are SIE motivations and personality traits which interest companies, that organizations have some SIE strategies which are for the most part focused on the essentials, that expatriates’ motives are generally integrated into HRM policies and programs, and lastly that companies are generally aware that they do not have properly established policies specifically targeted towards SIEs. They identify a lack of resources as the main reason for this but have ideas for implementing better strategies in the future. Finally, I note the implications which the findings can have in practical terms, the study’s limitations and future research topics.O objectivo deste estudo é examinar como, se de fato, empresas utilizam o que foi descoberto sobre as motivações dos expatriados auto-iniciados (EIE) para atrair, contratar, desenvolver e reter indivíduos de alto valor provenientes de países estrangeiros. Para este fim, foram formulados múltiplos objectivos e hipóteses de investigação através de uma revisão bibliográfica. Estes abrangem as principais motivações dos EIE para expatriar; em quais destas motivações as empresas estão interessadas; quais são os programas e políticas de empresas para EIE; quanto estes motivos estão integrados nas estratégias; e como os profissionais de recursos humanos os avaliam criticamente. Foram realizadas entrevistas com onze organizações sediadas principalmente na Alemanha para responder a estas questões. Com estas conclusões, foi possível verificar se as questões de investigação e, portanto, as hipóteses foram apoiadas ou não. Concluo que os profissionais de Gestão de Recursos Humanos (GRH) podem parcialmente identificar as motivações dos EIE, que existem motivações e traços de personalidade dos SIE que interessam às empresas, que as organizações têm algumas estratégias de SIE que estão, na sua maioria, centradas no essencial, que os motivos dos expatriados são geralmente integrados nas políticas e programas de GRH, e por último que empresas geralmente têm consciência de que não têm políticas devidamente estabelecidas especificamente orientadas para EIE. Identificam a falta de recursos como a principal razão para tal, mas têm ideias para implementar melhores estratégias no futuro. Finalmente, registro as implicações que as conclusões podem ter em prática, as limitações do estudo e tópicos de futuras investigações

Cathodoluminescent Properties of Single Crystal Materials for Electron Microscopy

The results of measurements of cathodoluminescence efficiencies, decay characteristics and emission spectra of YAG:Ce, YAP:Ce, P47 (Y2SiO5:Ce) and CaF2:Eu single crystals at excitation by electrons with an energy of 10 keV and a current density of the order of 10-8 A cm-2 are presented. Advantages and disadvantages of the individual single crystals intended for application in electron microscopes are dealt with. Attention is paid to the photomultiplier tube (PMT) matching, degradation and afterglow of the mentioned single crystals. For YAG:Ce, the effect of the activator concentration of crystals and the effect of the cleaning and annealing of crystal plates are included. The proposal for the application of YAG:Ce as a scintillator and as an image screen in electron microscopy is given. Sizes of electron interaction areas and absorbed energy distributions are simulated by using Monte Carlo method based on the plural large angle elastic scattering. Cathodoluminescence widths of YAG:Ce single crystals for an impact electron in the energy range 10-100 keV are estimated

Analysis of a Suitable Use of a Sports Centre in Brno - Líšeň

Hlavním cílem této diplomové práce je posouzení sportovního objektu z hlediska výhodnosti adaptace pro různé způsoby využití. Posuzovaným objektem je badmintonová hala nacházející se v ulici Úlehlova v Brně. Nejprve je popsán aktuální stav objektu a zhodnocen pomocí oceňovacích metod. Následně jsou stanoveny možné varianty využití sportovního objektu dle oblíbenosti halových sportů, nákladnosti, technické proveditelnosti a analýzy realitního trhu. Každá varianta je oceněna nákladovým, výnosovým a tržním způsobem. Nakonec je posouzena výhodnost jednotlivých variant a je vybrána ta nejvýhodnější z nich.The main objective of this diploma thesis is assessment of a sports centre according to a favourableness of adaptation to a different forms of utilization. The particular subject assessed is badminton sports centre located at Úlehlova street in Brno. First of all the current state of the sports centre is described and assessed by using valuation methods. Subsequently various possibilities of adaptation to different forms of utilization are determined according to a popularity of indoor sports, expensiveness, technical feasibility and analysis of a real estate market. Each variant is valued by cost, income and sales comparison approach. Eventually the favourableness of each variant is considered and the most favourable one is chosen

Integrated Single Crystal Detector for Simultaneous Detection of Cathodoluminescence and Backscattered Electrons in Scanning Electron Microscopy

The design of the majority of the available high efficiency cathodoluminescence (CL) detection systems allows the secondary electron (SE) and backscattered electron (BSE) image modes to be detected simultaneously to a limited degree only. The described CL-BSE detector is based on the single crystal YAG scintillator shaped as a spherical mirror which reflects photons emitted from the CL specimen and focuses them on to the entrance surface of a fibre optic light guide connected to the photomultiplier tube (PMT I). The backscattered electrons emitted from the CL specimen move through the reflecting layer of the mirror into the YAG scintillator where they are transformed into photons and guided using a fixed light guide to the PMT II. This allows the simultaneous recording of CL and BSE image modes without changing the specimen position. The detector design does not obstruct the simultaneous detection of SEs by the conventional SE detector. The examples of the simultaneous CL, SE and BSE detection given demonstrate deeper understanding of the specimens properties in different fields of science

Backscattered Electron Imaging for High Resolution Surface Scanning Electron Microscopy with a New Type YAG-Detector

Double Layer Coating for backscattered electron imaging is a coating and imaging method especially suitable for high resolution scanning electron microscopy (SEM) of large biological samples. Since the backscattered electron (BSE) signal from thin metal coating layers is quite low, field emission SEM\u27s and very sensitive BSE-detectors are required for this method. In this study an improved BSE-detector of the YAG type was used with an in-lens type field emission SEM. Two samples were investigated in order to demonstrate and to improve the potential of this new approach: (1) cryo-prepared cultured kidney cells were shadowed by electron beam evaporation with platinum-carbon (unidirectionally at a fixed angle of 45°) and then coated with an additional 10 nm carbon layer; and (2) cryo-prepared trichocyst matrixes (paracrystalline structures contained in secretory granules, the trichocysts, found in Paramecium) were coated by ion beam sputtering with about 1 nm of platinum. This sample was rotated and tumbled during coating in order to obtain as uniform a metal layer as possible and then an additional 10 nm carbon layer was evaporated over the metal. When these samples were viewed at a primary beam accelerating voltage (Vo) of 10 kV or higher, contrast was good on the unidirectionally coated cell culture samples. However, trichocyst matrixes with the thinner and more uniform coating showed very poor contrast because most of the BSE detected represented beam-specimen interactions from the bulk of the sample and not in the thin platinum layer. The situation was improved by using low Vo (4 kV). Under these conditions the penetration depth of the electrons is reduced and a greater proportion of the BSE electrons are scattered by the platinum layer. The results were compared with freeze-fracture and deep-etch transmission electron microscope studies of the trichocyst matrixes from the literature: Almost similar resolution is achieved on the biological structures but a better impression of the three dimensional arrangement of the whole trichocyst matrix is obtained with the SEM. The globular particles form disc-like structures that are connected with each other by thin fibers

The Changes of Posterior Corneal Surface and High-Order Aberrations after Refractive Surgery in Moderate Myopia

PURPOSE: To compare forward shift of posterior corneal surface and higher-order aberration (HOA) changes after LASIK, LASEK, and wavefront-guided LASEK surgery in moderate myopia METHODS: One hundred eighty four eyes undergoing LASIK, LASEK and wavefront-guided LASEK with VISX STAR S4 were included in this study. The posterior corneal elevation was measured with Orbscan before, 2 and 4 months after surgery. Changes of the elevation were assessed using the difference map generated from preoperative and postoperative elevation maps. The values of higher-order aberrations were evaluated preoperatively and 2 months postoperatively with Wavefront aberrometer. RESULTS: The posterior corneal surface displayed forward shift of 27.2+/-11.45 micrometer, 24.3+/-9.76 micrometer in LASIK group, 23.4+/-10.5 micrometer, 23.6+/10.55 micrometer in LASEK group, 24.0+/-14.95 micrometer, 28.4+/-14.72 micrometer in wavefront-guided LASEK group at 2 months and 4 months, respectively. There were no statistically significant differences among those three groups, and between 2 and 4 months. The root mean score (RMS) of HOA was increased after LASIK and LASEK (p=0.000, p=0.000, respectively). The mean change of HOA-RMS was significantly smaller in wavefront-guided LASEK than LASIK or LASEK (p=0.000, p=0.000, respectively, Bonferroni-corrected). CONCLUSIONS: The changes of posterior corneal surface forward shift showed no difference among LASIK, LASEK and wavefront-guided LASEK in moderate myopia. HOAs were significantly increased after LASIK and LASEK. The changes of HOAs were significant smaller in wavefront-guided LASEK than LASIK or LASEK

The global retinoblastoma outcome study : a prospective, cluster-based analysis of 4064 patients from 149 countries

DATA SHARING : The study data will become available online once all analyses are complete.BACKGROUND : Retinoblastoma is the most common intraocular cancer worldwide. There is some evidence to suggest that major differences exist in treatment outcomes for children with retinoblastoma from different regions, but these differences have not been assessed on a global scale. We aimed to report 3-year outcomes for children with retinoblastoma globally and to investigate factors associated with survival. METHODS : We did a prospective cluster-based analysis of treatment-naive patients with retinoblastoma who were diagnosed between Jan 1, 2017, and Dec 31, 2017, then treated and followed up for 3 years. Patients were recruited from 260 specialised treatment centres worldwide. Data were obtained from participating centres on primary and additional treatments, duration of follow-up, metastasis, eye globe salvage, and survival outcome. We analysed time to death and time to enucleation with Cox regression models. FINDINGS : The cohort included 4064 children from 149 countries. The median age at diagnosis was 23·2 months (IQR 11·0–36·5). Extraocular tumour spread (cT4 of the cTNMH classification) at diagnosis was reported in five (0·8%) of 636 children from high-income countries, 55 (5·4%) of 1027 children from upper-middle-income countries, 342 (19·7%) of 1738 children from lower-middle-income countries, and 196 (42·9%) of 457 children from low-income countries. Enucleation surgery was available for all children and intravenous chemotherapy was available for 4014 (98·8%) of 4064 children. The 3-year survival rate was 99·5% (95% CI 98·8–100·0) for children from high-income countries, 91·2% (89·5–93·0) for children from upper-middle-income countries, 80·3% (78·3–82·3) for children from lower-middle-income countries, and 57·3% (52·1-63·0) for children from low-income countries. On analysis, independent factors for worse survival were residence in low-income countries compared to high-income countries (hazard ratio 16·67; 95% CI 4·76–50·00), cT4 advanced tumour compared to cT1 (8·98; 4·44–18·18), and older age at diagnosis in children up to 3 years (1·38 per year; 1·23–1·56). For children aged 3–7 years, the mortality risk decreased slightly (p=0·0104 for the change in slope). INTERPRETATION : This study, estimated to include approximately half of all new retinoblastoma cases worldwide in 2017, shows profound inequity in survival of children depending on the national income level of their country of residence. In high-income countries, death from retinoblastoma is rare, whereas in low-income countries estimated 3-year survival is just over 50%. Although essential treatments are available in nearly all countries, early diagnosis and treatment in low-income countries are key to improving survival outcomes.The Queen Elizabeth Diamond Jubilee Trust and the Wellcome Trust.https://www.thelancet.com/journals/langlo/homeam2023Paediatrics and Child Healt