Systematic design of microscope objectives

The modern microscope objective is the most sophisticated optical component in light microscopes, providing high contrast images with diffraction-limited resolution. The design of microscope objectives has been developed for over a hundred of years. However, after 1970s, the review of advanced application-oriented systems is limited, and the design principles are not clear to most optical designers who are not the specialist from a few microscope manufacturers. To subtract off the hidden assumptions during the historical development and turn back to the intrinsic building blocks of the high numerical aperture (NA) systems, in this work, a systematic analysis and synthesis approach for microscope objectives is worked out, which is not found in available literature. The microscope objective patents are collected worldwide. Concentrating on the standardized objectives with color correction at least in the visible spectrum, a large system database is built up within Zemax/OpticStudioTM. According to a systematic review of the historical development, new classifications of the modern microscope objectives are proposed to understand the system complexity. Thereby, systematic analysis of the systems can be conducted to decouple the impact of aberration correction, application and manufacturing requests. Based on the decoupled results, the building blocks and design principles of the modern microscope objectives are systematically analyzed and summarized. Lens modules are sorted with respect to the general optical power distribution and individual structural lens groups. The reasons for many commonly used complicated structures are explained. Utilizing the lens modules, the microscope objective design can be more systematic. Both the modification of existing systems and the synthesis of new structures are realized, which give optical designers new ideas or possible opportunities to keep away from the restriction of other patents

RTVis: Research Trend Visualization Toolkit

When researchers and practitioners are about to start a new project or have just entered a new research field, choosing a proper research topic is always challenging. To help them have an overall understanding of the research trend in real-time and find out the research topic they are interested in, we develop the Research Trend Visualization toolkit (RTVis) to analyze and visualize the research paper information. RTVis consists of a field theme river, a co-occurrence network, a specialized citation bar chart, and a word frequency race diagram, showing the field change through time respectively, cooperating relationship among authors, paper citation numbers in different venues, and the most common words in the abstract part. Moreover, RTVis is open source and easy to deploy. The demo of our toolkit and code with detailed documentation are both available online.Comment: Work submitted to IEEE VIS 2023 (Poster). 2 pages, 1 figure. For our demo page, visit http://www.rtvis.design

Inferring the solution space of microscope objective lenses using deep learning

Lens design extrapolation (LDE) is a data-driven approach to optical design that aims to generate new optical systems inspired by reference designs. Here, we build on a deep learning-enabled LDE framework with the aim of generating a significant variety of microscope objective lenses (MOLs) that are similar in structure to the reference MOLs, but with varied sequences—defined as a particular arrangement of glass elements, air gaps, and aperture stop placement. We first formulate LDE as a one-to-many problem—specifically, generating varied lenses for any set of specifications and lens sequence. Next, by quantifying the structure of a MOL from the slopes of its marginal ray, we improve the training objective to capture the structures of the reference MOLs (e.g., Double-Gauss, Lister, retrofocus, etc.). From only 34 reference MOLs, we generate designs across 7432 lens sequences and show that the inferred designs accurately capture the structural diversity and performance of the dataset. Our contribution answers two current challenges of the LDE framework: incorporating a meaningful one-to-many mapping, and successfully extrapolating to lens sequences unseen in the dataset—a problem much harder than the one of extrapolating to new specifications

Public Attitudes and Factors of COVID-19 Testing Hesitancy in the United Kingdom and China: Comparative Infodemiology Study.

BACKGROUND: Massive community-wide testing has become the cornerstone of management strategies for the COVID-19 pandemic. OBJECTIVE: This study was a comparative analysis between the United Kingdom and China, which aimed to assess public attitudes and uptake regarding COVID-19 testing, with a focus on factors of COVID-19 testing hesitancy, including effectiveness, access, risk perception, and communication. METHODS: We collected and manually coded 3856 UK tweets and 9299 Chinese Sina Weibo posts mentioning COVID-19 testing from June 1 to July 15, 2020. Adapted from the World Health Organization's 3C Model of Vaccine Hesitancy, we employed social listening analysis examining key factors of COVID-19 testing hesitancy (confidence, complacency, convenience, and communication). Descriptive analysis, time trends, geographical mapping, and chi-squared tests were performed to assess the temporal, spatial, and sociodemographic characteristics that determine the difference in attitudes or uptake of COVID-19 tests. RESULTS: The UK tweets demonstrated a higher percentage of support toward COVID-19 testing than the posts from China. There were much wider reports of public uptake of COVID-19 tests in mainland China than in the United Kingdom; however, uncomfortable experiences and logistical barriers to testing were more expressed in China. The driving forces for undergoing COVID-19 testing were personal health needs, community-wide testing, and mandatory testing policies for travel, with major differences in the ranking order between the two countries. Rumors and information inquiries about COVID-19 testing were also identified. CONCLUSIONS: Public attitudes and acceptance toward COVID-19 testing constantly evolve with local epidemic situations. Policies and information campaigns that emphasize the importance of timely testing and rapid communication responses to inquiries and rumors, and provide a supportive environment for accessing tests are key to tackling COVID-19 testing hesitancy and increasing uptake

Revisiting the complex time-varying effect of non-pharmaceutical interventions on COVID-19 transmission in the United States

IntroductionAlthough the global COVID-19 emergency ended, the real-world effects of multiple non-pharmaceutical interventions (NPIs) and the relative contribution of individual NPIs over time were poorly understood, limiting the mitigation of future potential epidemics.MethodsBased on four large-scale datasets including epidemic parameters, virus variants, vaccines, and meteorological factors across 51 states in the United States from August 2020 to July 2022, we established a Bayesian hierarchical model with a spike-and-slab prior to assessing the time-varying effect of NPIs and vaccination on mitigating COVID-19 transmission and identifying important NPIs in the context of different variants pandemic.ResultsWe found that (i) the empirical reduction in reproduction number attributable to integrated NPIs was 52.0% (95%CI: 44.4, 58.5%) by August and September 2020, whereas the reduction continuously decreased due to the relaxation of NPIs in following months; (ii) international travel restrictions, stay-at-home requirements, and restrictions on gathering size were important NPIs with the relative contribution higher than 12.5%; (iii) vaccination alone could not mitigate transmission when the fully vaccination coverage was less than 60%, but it could effectively synergize with NPIs; (iv) even with fully vaccination coverage >60%, combined use of NPIs and vaccination failed to reduce the reproduction number below 1 in many states by February 2022 because of elimination of above NPIs, following with a resurgence of COVID-19 after March 2022.ConclusionOur results suggest that NPIs and vaccination had a high synergy effect and eliminating NPIs should consider their relative effectiveness, vaccination coverage, and emerging variants

The determinants of vaccine hesitancy in China: A cross-sectional study following the Changchun Changsheng vaccine incident.

INTRODUCTION: Vaccine hesitancy is cited as one of the top threats to global health. The Changchun Changsheng Biotechnology Company was found to have violated good manufacturing practices in July 2018, leading to widespread distribution of sub-potent vaccines in China. We estimated the prevalence and determinants of vaccine hesitancy following the Changchun Changsheng vaccine incident (CCVI). METHODS: We conducted a cross-sectional survey in China in January 2019, and 2,124 caregivers of children < 6 years old completed self-administered questionnaires. Multinomial logistic regression was used to assess the determinants of vaccine hesitancy; the potential determinants included demographics, socioeconomic status, vaccine confidence, and knowledge of the CCVI. Adjusted Odds Ratios (AORs) and 95% confidence intervals (CI) are reported. RESULTS: Around 89% of caregivers had heard of the CCVI. Although 83% and 88% of caregivers agreed that vaccines are safe and effective, respectively, 60% expressed some hesitancy about vaccination. Of those hesitant, 26% vaccinated their children at times with doubts, 31% delayed vaccination and 3% refused specific vaccines. Multinomial regression analysis showed that confidence in vaccine safety was associated with a reduced odds of doubts on vaccination (AOR = 0.64; 95%CI = 0.44-0.94), whereas caregivers who had heard of the CCVI had a significantly higher odds of doubts on vaccination (AOR = 1.61; 95%CI = 1.05-2.45). Confidence in the vaccine delivery system and government were associated with a lower odds of vaccine hesitancy. Caregivers with higher education and Buddhism or other religions were significantly more hesitant to vaccinate their children. CONCLUSION: Vaccine hesitancy was prevalent following the CCVI. Over half the caregivers either accepted childhood vaccination with doubts or delayed vaccines; only a small number were active refusers. Our findings highlight the importance of addressing vaccine hesitancy, especially following vaccine incidents. Tailored communications are needed to reduce vaccine hesitancy, especially among the highly educated and Buddhist caregivers

Vaccination coverage determinants in low uptake areas of China: a qualitative study of provider perspectives in Sichuan, Guangdong, and Henan Provinces.

China's immunization programme is relatively strong, with latest WHO-UNICEF monitoring rates for 2019 showing national vaccination coverage over 90%. However, vaccination coverage is heterogeneous, varying across geographic regions, rural-urban communities, and sub-populations. We conducted a qualitative study from a critical realist perspective, analyzing semi-structured interviews with 26 vaccination providers in three provinces, selected to represent regional socioeconomic disparities across Eastern, Central, and Western China. We analyzed data thematically, using deductive and inductive coding. Providers reported vaccination coverage in their areas had increased significantly, but remained lower among migrant and left-behind children. Main coverage determinants were child-related (i.e. gender, number, health status), caregiver-related (i.e. socioeconomic status, role, education level, ethnicity), institution-related (i.e. vaccinator numbers, information system, appointment process), and system-related (i.e. vaccine supply, intersectoral cooperation, vaccine 'hesitancy'). Potentially effective measures to promote vaccination coverage included using routine maternal and child health-care visits for catch-up vaccination, providing additional health education, conducting follow-up family visits by village doctors, and requiring vaccination verification at school enrollment. This is the first qualitative study to examine potential determinants of low vaccination coverage in these areas of China. Findings can inform policies to strengthen the role of schools, develop the national immunization information system, and promote appointment apps. More consideration is needed to improve service quality and eliminating inequities, such as strengthening health education and service provision for migrant and left-behind children

Access to Vaccination Information and Confidence/Hesitancy Towards Childhood Vaccination: A Cross-Sectional Survey in China.

Access to vaccination information could influence public attitudes towards vaccination. This study investigated the number and types of vaccination-related information sources, and estimated their associations with vaccine confidence and hesitancy in China. In January 2019, we conducted a cross-sectional survey in China, and 2122 caregivers with children <6 years completed self-administered questionnaires. Logistic regressions were used to assess associations between caregivers' primary information sources and vaccine confidence/hesitancy. A majority (72%) of caregivers had multiple sources of vaccination-related information. The proportions of caregivers reporting professional sources, media, and peers as primary information sources were 81%, 63%, and 26%. Internal migrants were less likely to get information from professional sources; more educated and wealthier caregivers reported more information sources and were more likely to get information from media and peers. Caregivers who reported professional information sources had significantly higher odds of being confident about the safety of vaccines and lower odds of being hesitant toward vaccination than those who did not. Caregivers who reported the media as a primary information source had significantly higher odds of being hesitant toward vaccination than those who did not. To address vaccine hesitancy, it is essential to promote universal access to professional vaccination-related information sources, and to use the media to disseminate evidence-based information and clarify misinformation. Health communication should target internal migrants, and more educated and wealthier caregivers

Pre-study for conversion of a gas turbine from liquid to gaseous fuel

Thesis (MEng)--Stellenbosch University, 2016.ENGLISH ABSTRACT: Gaseous fuel has shown its benefits as a promising alternative energy source. In an effort to research the effect of gaseous fuel on gas turbines, a Rover 1S/60 gas turbine was used for the fuel conversion study. This thesis aims to establish a test cell for small gas turbine testing and conduct engine tests with liquid and gaseous fuel. Therefore, a test setup was built from scratch including the fuel supply system, data acquisition system, electronic/mechanical remote control system and emergency shutdown system. The engine used for the test was disassembled and overhauled to study the detailed mechanics of each component so that further modification work could be carried out. After conducting several engine tests with kerosene, it was found the maximum continuous power output decreased from the factory rating of 45 kW to 28.4 kW and many of the measured data did not meet the requirements set by the Rover Company. Therefore, a new operation standard and procedure were set to meet the current condition of the engine. Finally, a newly designed gaseous fuel supply and control system were installed. With a modified gas injector, the engine was successfully converted to operate with LPG, and other gaseous fuels could in principle also be used for further tests.AFRIKAANSE OPSOMMING: Gas brandstowwe het verskeie voordele as ’n alternatiewe energie bron. Om die effek van die gebruik van ’n gas brandstof op ’n gasturbine te evalueer, is ’n Rover 1S/60 gas turbine ondersoek. Hierdie studie beoog om ’n toetssel vir klein gasturbine toetse te vestig en enjintoetse met vloeistof- en gas-brandstowwe uit te voer. Daar is dus ’n eksperimentele opstel gebou wat bestaan uit: ’n brandstof toevoer-, data-versameling- en elektroniese/meganiese afstandbeheer sisteem, so wel as ’n nood-afskakel sisteem. Die gasturbine wat gebruik is in die studie is uit mekaar gehaal, skoongemaak en elke komponent deeglik ondersoek, voordat die gasturbine weer aan mekaar gesit is en die nodige aanpassings gemaak is. Na talle enjintoetslopies met keroseen as verkose brandstof, is daar bevind dat die maksimum onderbroke krag uitset 28.4 kW is, laer as die fabriek-gespesifiseerde waarde van 45 kW. Daar is ook bevind dat verskeie van die gemete waardes nie aan die vereistes, soos gestel deur Rover Company, voldoen nie. Daarom is daar nuwe operasionele standaarde en prosedures in plek gestel om te pas by die huidige toestand van die enjin. Laastens is ’n nuwe gas brandstof toevoer- en beheer stelsel geinstalleer. Met die aangepaste gas inlaat, is die enjin suksesvol omskep om op LPG te loop, en ander gas brandstowwe kan in toekomstige toetse gebruik word