345 research outputs found
Processing Chain for Localization of Magnetoelectric Sensors in Real Time
The knowledge of the exact position and orientation of a sensor with respect to a source (distribution) is essential for the correct solution of inverse problems. Especially when measuring with magnetic field sensors, the positions and orientations of the sensors are not always fixed during measurements. In this study, we present a processing chain for the localization of magnetic field sensors in real time. This includes preprocessing steps, such as equalizing and matched filtering, an iterative localization approach, and postprocessing steps for smoothing the localization outcomes over time. We show the efficiency of this localization pipeline using an exchange bias magnetoelectric sensor. For the proof of principle, the potential of the proposed algorithm performing the localization in the two-dimensional space is investigated. Nevertheless, the algorithm can be easily extended to the three-dimensional space. Using the proposed pipeline, we achieve average localization errors between 1.12 cm and 6.90 cm in a localization area of size 50cmĂ50cm
Total synthesis and structural assignment of (â)-fusaequisin A
(â)-Fusaequisin A is an irregularly assembled polyketide isolated from the ascomycete Fusarium equiseti. Fusaequisin A shares a carbon backbone with curvicollide C from the ascomycete Podospora curvicolla but its absolute configuration remained hitherto unsettled. Herein, we document the total synthesis of (â)-fusaequisin A and its 4-O-desmethyl derivative following a central-to-lateral building block strategy. Catalytic asymmetric Claisen rearrangement, Julia-Kocienski olefination and olefin cross-metathesis served as key C/C-connecting transformations. The constitution and absolute configuration of (â)-fusaequisin A was deduced and the original structural assignment was adjusted
Totalsynthese und StrukturaufklÀrung von Fusaequisin A und Studien zur Synthese der Ostseitenkette von Curvicollid B
The polyketide fusaequisin A was isolated in 2013 by Shiono et al. from the endophytic fungus Fusarium equiseti. The fungus was discovered in a suburb of Yaounde, Cameroon. Fusaequisin A has a high structural similarity to the Curvicollides. These polyketides were isolated from the mycoparasitic organism Podospora curvicolla by Gloer et al. in 2004. The fungus had infected the surface of an Aspergillus flavus sclerotium buried in a cornfield in Illinois, USA. The natural product producers were collected in different ecosystems on different continents and differ not only in their phylogenetic classification but also in their morphological characteristics. This raises the question of how the high structural similarity of the natural products occurs. The isolators were not able to elucidate the absolute configuration of the natural products and the relative configuration could only be assigned for the central heterocycle (all-trans).
The present dissertation deals with the total synthesis and structural elucidation, in terms of constitution and configuration, of fusaequisin A and initial studies on the synthesis of curvicollide B. The natural products are to be built up by two key linkage steps (cross-metathesis and JuliaKocienski olefination). The three retrosynthetic fragments, the Western, the Central, and the Eastern fragment, allow a convergent synthesis and should be linked at the latest possible stage of synthesis. Total synthesis of fusaequisin A allowed comparison of the analytical data with those of the isolated natural product. This allowed not only the absolute configuration to be elucidated, but also the constitutional structure elucidation to be corrected.Der polyketide Naturstoff Fusaequisin A wurde 2013 von Shiono et al. aus dem endophytischen Pilz Fusarium equiseti isoliert, der in einem Vorort von Yaunde in Kamerun entdeckt wurde. Fusaequisin A weist hohe strukturelle Ăhnlichkeiten zu den Curvicolliden auf, die 2004 von Gloer et al. aus dem my-koparasitĂ€ren Organismus Podospora curvicolla isoliert werden konnten. Der Pilz hatte die OberflĂ€che eines auf einem Kornfeld in Illinois, USA vergrabenen Sklerotiums von Aspergillus flavus befallen. Die Naturstoffproduzenten wurden in verschiedenen Ăkosystemen auf unterschiedlichen Kontinenten ge-sammelt und unterscheiden sich nicht nur in ihrer phylogenetischen Klassifizierung, sondern auch hin-sichtlich ihrer morphologischen Eigenschaften. Dadurch stellt sich die Frage, wie es zu der hohen strukturellen Ăhnlichkeit der Naturstoffe kommt. Den Isolierern gelang es nicht, die absolute Konfigu-ration der Naturstoffe aufzuklĂ€ren und auch die relative Konfiguration konnte nur fĂŒr den zentralen Heterozyklus ermittelt werden (all-trans).
Die vorliegende Dissertation beschĂ€ftigt sich mit der Totalsynthese und StrukturaufklĂ€rung von Fusaequisin A im Hinblick auf Konstitution und Konfiguration und ersten Studien zur Synthese von Curvicollid B. Die Naturstoffe sollen durch zwei zentrale VerknĂŒpfungsschritte (Kreuzmetathese und JuliaKocienski-Olefinierung) aufgebaut werden. Die drei retrosynthetischen Bausteine, West-, Mittel- und Ostfragment, ermöglichen eine konvergente Synthese und sollen auf einer möglichst spĂ€ten Stu-fe der Synthese verknĂŒpft werden. Die Totalsynthese von Fusaequisin A ermöglichte den Vergleich der analytischen Daten mit denen des isolierten Naturstoffes. Dadurch konnte nicht nur die die abso-lute Konfiguration aufgeklĂ€rt, sondern auch die konstitutionelle StrukturaufklĂ€rung korrigiert werden
Active Magnetoelectric Motion Sensing: Examining Performance Metrics with an Experimental Setup
Magnetoelectric (ME) sensors with a form factor of a few millimeters offer a comparatively low magnetic noise density of a few pT/Hzââââ in a narrow frequency band near the first bending mode. While a high resonance frequency (kHz range) and limited bandwidth present a challenge to biomagnetic measurements, they can potentially be exploited in indirect sensing of non-magnetic quantities, where artificial magnetic sources are applicable. In this paper, we present the novel concept of an active magnetic motion sensing system optimized for ME sensors. Based on the signal chain, we investigated and quantified key drivers of the signal-to-noise ratio (SNR), which is closely related to sensor noise and bandwidth. These considerations were demonstrated by corresponding measurements in a simplified one-dimensional motion setup. Accordingly, we introduced a customized filter structure that enables a flexible bandwidth selection as well as a frequency-based separation of multiple artificial sources. Both design goals target the prospective application of ME sensors in medical movement analysis, where a multitude of distributed sensors and sources might be applied
Non-utilisation of health care services during the COVID-19 pandemic: Results of the CoMoLo study
Based on data from the CORONA-MONITORING lokal (CoMoLo) study conducted in four municipalities particularly affected by the COVID-19 pandemic, this article investigates the non-utilisation of health care services in the population aged 18 years and older (n=9,002) in relation to the period after the introduction of the containment measures in March 2020. The results show that about one third of the respondents (35.5%) gave up at least one of the surveyed health care services. The most frequent cancellations were dental (15.2%) and specialist check-ups (11.8%), followed by postponement of physiotherapy, ergotherapy or speech therapy (6.1%), cancellation of general practitioner (GP) check-ups (5.8%), postponement of psychotherapy (2.0%), postponement of planned hospital treatment (1.8%) and not going to an emergency room (0.7%). Almost 10% of the respondents reported not visiting a physician despite health complaints. Compared to respondents without such a waiver, these respondents were more often female and younger than 35 years, less often rated their health as very good or good, more often had a diagnosis of depression and more often used telemedical contacts as an alternative to visiting the practice during the pandemic. Further analyses of trends in utilisation behaviour and changes in health status over the course of the COVID-19 pandemic are important
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