Construction of a low background facility for the COBRA experiment and its performance

The COBRA experiment is investigating neutrinoless double-beta decays of Cd, Zn and Te isotopes with an array of CdZnTe semiconductor detectors. The current development stage consists of 64 CPG-type detectors of 1 ccm size each that will be arranged in form of a 3-dimensional 4 × 4 × 4-array. At the time of writing, the first 16-detector layer was installed and has been collecting data since January 2007. The remaining three layers are currently being assembled. Within the course of this work, key experimental components for the COBRA setup have been developed, among them several versions of custom-built preamplifiers, shapers and large parts of COBRA’s VME-based ADC. Furthermore, the detector suspension and contacting were completely re-designed and the shielding concept was significantly enhanced. Based on roughly 4.2 kg · d of data collected with the first operational 16-detector layer, a coincidence-based analysis has been performed focusing on neutrinoless double-beta decays of Cd-116, Te-128 and Te-130 into excited states. For one of the decays, previously published limits on the half-life could be improved. Moreover, the power of the coincidence analysis method was demonstrated for decays involving gamma emission

Experimental analysis on the influence of freeform bending on Barkhausen noise for steel tubes

Freeform bending with a movable die makes it possible to bend complex structures and seamless radii without changing the bending tools. Currently, most research focuses on minimizing the geometrical deviations without considering the mechanical properties of the bent tubes. A previous work showed, that the geometry can be decoupled from the mechanical properties with non-tangential bending [1]. The implementation of a soft sensor based on ultrasonic contact impedance measurements (UCI) of the property-controlled freeform bending has also been examined [2], as well as a structure for closed-loop control based on material properties [3]. The present work deals with a micro-magnetic sensor and Barkhausen noise (BHN) and investigates its suitability for the closed-loop control. For this purpose, different processing routes for freeform-bent steel tubes are experimentally investigated by their characteristic BHN. In addition to an existing simulation model, a data basis for the impact of freeform bending parameters is built to extend the existing model of a property-based closed-loop control

Increasing hepatitis B vaccination coverage and decreasing hepatitis B co-infection prevalence among people with HIV-1 in Germany, 1996–2019. Results from a cohort study primarily in men who have sex with men

Objectives Viral hepatitis co-infection among people living with HIV is known to accelerate the progression of liver disease and AIDS. An increased prevalence and incidence of hepatitis B virus (HBV) infection among people living with HIV demands continuous monitoring to adapt targeted prevention strategies to reach the global goals of eliminating viral hepatitis as a public health threat. Methods We determined the prevalence and incidence of HBV for the years 1996–2019 from yearly blood sample testing and questionnaire reports among people living with HIV belonging to a nationwide, multicentre observational, prospective cohort study. Results Among this study population of 3479 participants, the majority (87%) indicated that being men who have sex with men (MSM) was their likely HIV transmission route; 51% were recruited from Berlin. HBV prevalence for acute/chronic and resolved infections decreased from 4.1% and 45% in 1996–1999 to 1.3% and 16% in 2019, respectively. Simultaneously, participants with a serological status indicating HBV vaccination increased from 25% in 1996–1999 to 69% in 2019. Among vaccinated participants with relevant information (n = 1135), 38% received their first HBV vaccination after HIV infection. The HBV incidence rate in 565 eligible participants decreased from 6.9/100 person-years in 2004–2007 to 0.45/100 person-years in 2015. Conclusion Increasing vaccination coverage because of a general HBV vaccination recommendation and catch-up vaccination efforts among risk groups decreased HBV infection prevalence over time among this study population of people living with HIV, primarily MSM and from Berlin. Despite this success, the prevalence and incidence of HBV remains higher than in the general population in Germany. This emphasizes the need for continued HBV prevention by promoting HBV vaccination and HBV screening at regular intervals based on the individual risk behaviour.Peer Reviewe

Decreasing prevalence and stagnating incidence of Hepatitis C-co-infection among a cohort of HIV-1-positive patients, with a majority of men who have sex with men, in Germany, 1996–2019

Co-infection with Hepatitis C virus (HCV) among HIV-positive patients leads to accelerated progression of liver disease and AIDS. Due to increased HCV prevalence and incidence, co-infection requires monitoring trends among HIV-positive individuals. This will help target prevention strategies and support to reach the global goals of eliminating viral hepatitis as a public health threat. In this analysis HCV prevalence and incidence were determined for the years 1996–2019 from yearly blood samples and questionnaire details among HIV-1-positive patients, with a majority of men who have sex with men, belonging to a nationwide, multicentre observational, prospective cohort study. The results show that HCV prevalence for acute/chronic and resolved infection increased until 2014 to 12%. Since then, prevalence of acute/chronic HCV infection rapidly decreased and prevalence of resolved infections showed a steady increase. HCV incidence was highest in 2010 and lowest in 2017; however, no significant change in HCV incidence could be seen over the years. Therefore, the introduction of directly-acting antiviral agents for HCV treatment notably decreased prevalence and potentially incidence of acute/chronic HCV infection. Nevertheless, prevalence and incidence of HCV among these HIV-1-positive study participants remain high compared with the general population and justify the need for continuous HCV prevention and treatment efforts among HIV-positive individuals.Peer Reviewe

Control System Design for a Semi-Finished Product Considering Over- and Underbending

In the last decades, the application of automatic control techniques in freeform bending processes was limited to the motion control of the bending die, i.e., the workpiece itself was not considered inside the closed-loop control system. In a previous work, a simple preliminary model for the workpiece was used as a foundation for developing a closed-loop system for freeform bending that includes both the geometry and the mechanical properties of the semi-finished product. However, this approach did not consider the fact that the same geometry can be reached by either over- or underbending the tube. In this work, the previously developed system model is extended to include this physical property of the system

A System Identification and Implementation of a Soft Sensor for Freeform Bending

The primary goal of this study is the formulation of a soft sensor that predicts industrially relevant mechanical properties for freeform bending. This serves as the foundation of a closed-loop property control. It is hypothesized that by inline measurement of hardness, predictions regarding residual hoop stresses, local strength and strain level can be achieved. A novel hardness-based correlation scheme is introduced, which is implemented into an extended Kalman filter (EKF) and allows an inline prediction of local strength, residual hoop stresses and plasticity. Furthermore, the ultrasonic contact impedance (UCI) method is validated as a suitable inline measuring solution