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Results of WICOVIR Gargle Pool PCR Testing in German Schools Based on the First 100,000 Tests
(2021)
Background:
Opening schools and keeping children safe from SARS-CoV-2 infections at the same time is urgently needed to protect children from direct and indirect consequences of the COVID-19 pandemic. To achieve this goal, a safe, efficient, and cost-effective SARS-CoV-2 testing system for schools in addition to standard hygiene measures is necessary.
Methods:
We implemented the screening WICOVIR concept for schools in the southeast of Germany, which is based on gargling at home, pooling of samples in schools, and assessment of SARS-CoV-2 by pool rRT-PCR, performed decentralized in numerous participating laboratories. Depooling was performed if pools were positive, and results were transmitted with software specifically developed for the project within a day. Here, we report the results after the first 13 weeks in the project.
Findings:
We developed and implemented the proof-of-concept test system within a pilot phase of 7 weeks based on almost 17,000 participants. After 6 weeks in the main phase of the project, we performed >100,000 tests in total, analyzed in 7,896 pools, identifying 19 cases in >100 participating schools. On average, positive children showed an individual CT value of 31 when identified in the pools. Up to 30 samples were pooled (mean 13) in general, based on school classes and attached school staff. All three participating laboratories detected positive samples reliably with their previously established rRT-PCR standard protocols. When self-administered antigen tests were performed concomitantly in positive cases, only one of these eight tests was positive, and when antigen tests performed after positive pool rRT-PCR results were already known were included, 3 out of 11 truly positive tests were also identified by antigen testing. After 3 weeks of repetitive WICOVIR testing twice weekly, the detection rate of positive children in that cohort decreased significantly from 0.042 to 0.012 (p = 0.008).
Interpretation:
Repeated gargle pool rRT-PCR testing can be implemented quickly in schools. It is an effective, valid, and well-received test system for schools, superior to antigen tests in sensitivity, acceptance, and costs.
Die Verlegung von Kunststoffverbundmantelrohren (KMR) im Fernwärmeleitungsbau ausschließlich in zeitweise fließfähigen, selbstverdichtenden Verfüllbaustoffen (ZFSV) in der Leitungszone anstelle in Sand, ist weitgehend neu. Interesse an dieser Methode besteht aus technischer Sicht infolge höherer nachgewiesener Haltekräfte in Technikums- und Laborversuchen, die die Leitungsbewegungen reduzieren können. Es existiert jedoch noch kein praxistaugliches Berechnungsmodell bzw die Grundlagen hierfür. U.a. deswegen wird derzeit an der Ostbayerischen Technischen Hochschule Regensburg (OTH.R) das Forschungsvorhaben "EnEff: Wärme - Innovative Fernwärmeverteilung - Einsatz fließfähiger Verfüllbaustoffe zur KMR-Verlegung, Arbeitspaket Bodenmechanik" durchgeführt. Es wird im Referat der Unterschied der axialen Bettung von KMR in ZFSV und Sand anhand einer analytischen Lösung vorgestellt. Diese erlaubt die Berechnung von Verschiebungen und Normalkräften für das KMR für die Bettung in ZFSV erfolgt dies unter Verwendung der mittels eines neuartigen Versuchs(behalters) Re-SIST nun bestimmbaren bisher unbekannten Kontaktwiderstandsarbeitslinie zwischen ZFSV und PE. Zur Verdeutlichung der Unterschiede bei Sand- und ZFSV-Bettung werden Ergebnisse einer vergleichenden Berechnung an einer sonst identischen KMR-Leitung vorgestellt. Diese zeigen, dass in ZFSV die Verschiebungen geringer ausfallen und weniger Leitungslange in Bewegung ist, was sich mit Beobachtungen an einer Fernwärmeleitung in Ulm deckt. Die Ausführungen gelten für das erstmalige Warmgehen.
District heating cost reduction efforts are amongst others focusing on the use of a new backfillmaterial. The OTH.R is investigating this material in regard to the engineering of buried district heating pipes.The main focus of this soil-structure interaction problem is axial bedding to reduce thermal induced elongations.The backfill material is characterized and an axial non-linear spring-based calculation method is described.Centerpiece of the method is the contact-working-resistance-line (CWRL).A new Rod-Shear-Test based testingdevice Re-SIST to investigate the CWRL for the new backfill material is presented. The investigated CWRL isdescribed and compared to the CWRL for sand, which is the conventional backfill material. Solutions using thespring-based calculation method are presented and a comparative example of calculation shows the differencein axial bedding when the new backfill material is used.
Finite element (FE)–based studies of preoperative processes such as folding,pleating, and stent crimping with a comparison with experimental inflation tests are not yet available. Therefore, a novel workflow is presented in which residual stresses of balloon folding and pleating, as well as stent crimping, and the geometries of all contact partners were ultimately implemented in an FE code to simulate stent expansion by using an implicit solver. The numerical results demonstrate that the incorporation of residual stresses and strains experienced during the production step significantly increased the accuracy of the subsequent simulations, especially of the stent expansion model. During the preoperative processes, stresses inside the membrane and the stent material also reached a rather high level. Hence, there can be no presumption that balloon catheters or stents are undamaged before the actual surgery. The implementation of the realistic geometry, in particular the balloon tapers, and the blades of the process devices improved the simulation of the expansion mech-anisms, such as dogboning, concave bending, or overexpansion of stent cells. This study shows that implicit solvers are able to precisely simulate the mentioned preoperative processes and the stent expansion procedure without a preceding manipulation of the simulation time or physical mass.
Joining thermoplastic requisitions is a popular technique to build sophisticated plastic applications. Therefore the laser-transmission welding process is used to join thermoplastic polymers in visible regions. The clamping force in this case plays a decisive role when it comes to the weld quality. Simulating the clamping pressure with finite element techniques is therefore highly attractive to understand the principal of the process. Thermoplastic polymers under tensile load often show a brittle behavior coupled with softening. Simulating such materials is quite difficult for FEM programs. In this case a finite element study of the tensile test in LS-DYNA and ANSYS Wb 14 with respect to the material models was analysed. The experimental data get validated in comparison with the FEM solution for a tensile test. The material models and the problems in simulating softening behavior for thermoplastic polymers were discussed
Der wissenschaftliche Untersuchungsstand von Zeitweise fließfähigen, selbstverdichtenden Verfüllbaustoffen (ZSFV) unter Zugabe von Zement und/ oder Bentonit sowie Wasser zu Grundmaterial ist gering. Die OTH Regensburg (OTH.R) untersucht im Forschungsvorhaben EnEff systematisch verschiedene ZFSV für den Einsatz im Infrastrukturbau, speziell Fernwärmeleitungen. Neben der dort hauptsächlich interessierenden Kontaktmechanik zu axialen Temperaturdehnungsbehinderung werden bodenmechanische Eigenschaften und deren Zeitabhängigkeit untersucht. Im Beitrag werden nach einer einführenden Charakterisierung von ZFSV und kurzen Darstellung der Bedeutung der Zugabe von Zement und Bentonit Ergebnisse von bodenmechanischen Untersuchungen in Abhängigkeit des Materialalters und teilweise in Referenz zum Grundmaterial (hier: Boden) vorgestellt. Im Weiteren werden zwei auf ZFSV adaptierte, zementbasierte Prognosemodelle zur Vorhersage der zeitlichen Entwicklung der Druckfestigkeit vorgestellt.