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Integrated Array Tomography for 3D Correlative Light and Electron Microscopy

Volume electron microscopy (EM) of biological systems has grown exponentially in recent years due to innovative large-scale imaging approaches. As a standalone imaging method, however, large-scale EM typically has two major limitations: slow rates of acquisition and the difficulty to provide targeted biological information. We developed a 3D image acquisition and reconstruction pipeline that overcomes both of these limitations by using a widefield fluorescence microscope integrated inside of a scanning electron microscope. The workflow consists of acquiring large field of view fluorescence microscopy (FM) images, which guide to regions of interest for successive EM (integrated correlative light and electron microscopy). High precision EM-FM overlay is achieved using cathodoluminescent markers. We conduct a proof-of-concept of our integrated workflow on immunolabelled serial sections of tissues. Acquisitions are limited to regions containing biological targets, expediting total acquisition times and reducing the burden of excess data by tens or hundreds of GBs

Integrated Array Tomography for 3D Correlative Light and Electron Microscopy

Volume electron microscopy (EM) of biological systems has grown exponentially in recent years due to innovative large-scale imaging approaches. As a standalone imaging method, however, large-scale EM typically has two major limitations: slow rates of acquisition and the difficulty to provide targeted biological information. We developed a 3D image acquisition and reconstruction pipeline that overcomes both of these limitations by using a widefield fluorescence microscope integrated inside of a scanning electron microscope. The workflow consists of acquiring large field of view fluorescence microscopy (FM) images, which guide to regions of interest for successive EM (integrated correlative light and electron microscopy). High precision EM-FM overlay is achieved using cathodoluminescent markers. We conduct a proof-of-concept of our integrated workflow on immunolabelled serial sections of tissues. Acquisitions are limited to regions containing biological targets, expediting total acquisition times and reducing the burden of excess data by tens or hundreds of GBs.</p

Rotavirus and illness severity in children presenting with acute gastroenteritis at the primary care out-of-hours service

BACKGROUND: Rotavirus is a common cause of acute gastroenteritis in young children in the Netherlands, where rotavirus vaccination has not yet been implemented. OBJECTIVES: To evaluate a difference in illness severity course depending on the presence of rotavirus infection and assess the prevalence of viruses and the referral rate in children with acute gastroenteritis. METHODS: A prospective cohort of children aged 6 months to 6 years presenting with acute gastroenteritis to a primary care out-of-hours service from October 2016 to March 2018. Faeces were sampled and sent to a laboratory where viral pathogens were identified and quantified by real-time polymerase chain reaction. Severe course of acute gastroenteritis was defined as a Modified Vesikari Score of ≥11. In addition, we assessed referral rates. Chi-square tests were used to evaluate differences between groups. RESULTS: We included 75 children (34 boys) with a median age of 1.5 years (interquartile range, 0.9–2.0 years). The prevalence of rotavirus was 65.3% (95% confidence interval, 53.5–76.0) with a median cycle threshold of 16.0. Severe course of acute gastroenteritis was present in 31 of 71 children (4 were lost to follow-up). Those with rotavirus (20/47) did not have a severe course more often than those without (11/24): odds ratio, 0.88 (95% confidence interval, 0.33–2.36). Referral rates were comparable for rotavirus (15.2%) and non-rotavirus (14.3%). CONCLUSION: In out-of-hours primary care, rotavirus is common but not associated with increased severity and higher referral rates in children with acute gastroenteritis

Retarding Field Integrated Fluorescence and Electron Microscope

The authors present the application of a retarding field between the electron objective lens and sample in an integrated fluorescence and electron microscope. The retarding field enhances signal collection and signal strength in the electron microscope. This is beneficial for samples prepared for integrated fluorescence and electron microscopy as the amount of staining material added to enhance electron microscopy signal is typically lower compared to conventional samples in order to preserve fluorescence. We demonstrate signal enhancement through the applied retarding field for both 80-nm post-embedding immunolabeled sections and 100-nm in-resin preserved fluorescence sections. Moreover, we show that tuning the electron landing energy particularly improves imaging conditions for ultra-thin (50 nm) sections, where optimization of both retarding field and interaction volume contribute to the signal improvement. Finally, we show that our integrated retarding field setup allows landing energies down to a few electron volts with 0.3 eV dispersion, which opens new prospects for assessing electron beam induced damage by in situ quantification of the observed bleaching of the fluorescence following irradiation

E2 properties of nuclei far from stability and the proton-halo problem of 8B

E2 properties of A=6--10 nuclei, including those of nuclei far from stability, are studied by a $(0+2)\hbar\omega$ shell-model calculation which includes E2 core-polarization effects explicitly. The quadrupole moments and the E2 transition strengths in A=6--10 nuclei are described quite well by the present calculation. This result indicates that the relatively large value of the quadrupole moment of $^8$B can be understood without introducing the proton-halo in $^8$B. An interesting effect of the $2\hbar\omega$ core-polarization is found for effective charges used in the $0\hbar\omega$ shell model; although isoscalar effective-charges are almost constant as a function of nucleus, appreciable variations are needed for isovector effective-charges which play important roles in nuclei with high isospin-values.Comment: (LaTeX, 23 pages

Gasaustausch zwischen einem Helium enthaltenden Behälter und der Umgebung über ein nach unten abgehendes Rohr und dessen Relevanz für den HTR Modu

After a fracture of the fuel charge tube {$\varnothing$ = 65 mm) of a HTR-Modul-Reactor a rapid depressurization of the primary circuit occurs and thereafter a long-range gas exchange between primary circuit and containment takes place. Experiments related to the problem of gas exchange between a vessel and the environment via a vertically installed tube were carried out. For the calculation of the gas exchange rates a computer code was developed, which takes into account all mechanisms influencing the exchange rate in the experiment. The calculated values were in good agreement with the experimental results. The transformation of the results to a HTR-Modul shows that the gas exchange rate in the case of a charge tube fracture is only determined by gas expansion and contraction in the primary circuit. Therefore the amount of air entering the primary circuit is very small

Ausström- und Gasaustauschvorgänge nach Lecks im Primärkreislauf von Hochtemperaturreaktoren

The occurrence of leaks in the pressurized enclosure of an Helium cooled High Temperature Reactor leads in a first step to a rapid outflow of the cooling gas. After loss of pressure gas exchange processes start governd by convection, diffusion and the so called 'breathing'of the primary circuit. Theoretical models for the treatment of the processes are presented. Further experimental investigations are reported. The phenomena are discussed and theory and experiments are compared

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