Simulation based investigation of source-detector configurations for non-invasive fetal pulse oximetry

Transabdominal fetal pulse oximetry is a method to monitor the oxygen supply of the unborn child non-invasively. Due to the measurement setup, the received signal of the detector is composed of photons coding purely maternal and photons coding mixed fetal-maternal information. To analyze the wellbeing of the fetus, the fetal signal is extracted from the mixed component. In this paper we assess source-detector configurations, such that the mixed fetal-maternal components of the acquired signals are maximized. Monte-Carlo method is used to simulate light propagation and photon distribution in tissue. We use a plane layer and a spherical layer geometry to model the abdomen of a pregnant woman. From the simulations we extracted the fluence at the detector side for several source-detector distances and analyzed the ratio of the mixed fluence component to total fluence. Our simulations showed that the power of the mixed component depends on the source-detector distance as expected. Further we were able to visualize hot spot areas in the spherical layer model where the mixed fluence ratio reaches the highest level. The results are of high importance for sensor design considering signal composition and quality for non-invasive fetal pulse oximetry

Development of a phantom to modulate the maternal and fetal pulse curve for pulse oximetry measurements

For getting reliable information about the state of health from the fetus and the mother during labor and delivery, a fetal pulse oximeter is being developed. This paper describes the development of a special phantom to verify the algorithms for separating the weak fetal from the dominant maternal optical signal. To reach a realistic behavior it is necessary for two circulations to be controlled independently. Inspired by the natural blood circulation behavior, a RC-System with fixed resistance and capacity was created. Pumping a liquid with a roller pump into the tubes widens them. The digital signal processor (DSP) controls the expansion of the tube diameter by modifying the rotation velocity of the pump for active regulation. Therefore a soft and good enlargeable material was used. The measured values of the pressure sensor enabled active feedback for motor control The determined system characteristics are used to adapt the given pulse curve to the real system behavior. Via a LabView interface it is possible to change curve parameters like amplitude and frequency. The goal was to replicate the pulsation of the blood vessels like in the abdomen of a pregnant woman. Changing the parameters influences the modulation of the signal under consideration of the transfer function. With this phantom it is possible to simulate different scenarios, for example different states of pregnancy or pathogen indications

FPGA controlled artificial vascular system

Monitoring the oxygen saturation of an unborn child is an invasive procedure, so far. Transabdominal fetal pulse oximetry is a promising method under research, used to estimate the oxygen saturation of a fetus noninvasively. Due to the nature of the method, the fetal information needs to be extracted from a mixed signal. To properly evaluate signal processing algorithms, a phantom modeling fetal and maternal blood circuits and tissue layers is necessary. This paper presents an improved hardware concept for an artificial vascular system, utilizing an FPGA based CompactRIO System from National Instruments. The experimental model to simulate the maternal and fetal blood pressure curve consists of two identical hydraulic circuits. Each of these circuits consists of a pre-pressure system and an artificial vascular system. Pulse curves are generated by proportional valves, separating these two systems. The dilation of the fetal and maternal artificial vessels in tissue substitutes is measured by transmissive and reflective photoplethysmography. The measurement results from the pressure sensors and the transmissive optical sensors are visualized to show the functionality of the pulse generating systems. The trigger frequency for the maternal valve was set to 1 per second, the fetal valve was actuated at 0.7 per second for validation. The reflective curve, capturing pulsations of the fetal and maternal circuit, was obtained with a high power LED (905 nm) as light source. The results show that the system generates pulse curves, similar to its physiological equivalent. Further, the acquired reflective optical signal is modulated by the alternating diameter of the tubes of both circuits, allowing for tests of signal processing algorithms

Richard Löwenherz im Museum : Menschen und Objekte in Bewegung

Irgendwo in unserem sogenannten Allgemeinwissen über das Mittelalter ist auch die Vorstellung verankert, dass das Leben früher ruhiger, gemütlicher und nicht so hektisch war wie heute. Früher, als die Welt noch ‚normal’ war, hatten die meisten Menschen einen festen Lebensmittelpunkt, waren fest verwurzelt in einer Gemeinschaft und verließen ihre Heimat nur dann, wenn es sich gar nicht vermeiden lies. Nur wenige – nämlich die besonders Überprivilegierten und die besonders Unterprivilegierten -, also die, die es sich leisten konnten oder die, die dazu gezwungen wurden, waren unterwegs. Alle anderen blieben ein Leben lang zuhause, an dem Ort, an dem sie ihren festen Lebensmittelpunkt hatten. Soweit unser intuitives Vorwissen darüber, wie es früher, also auch schon im Mittelalter, gewesen sein muss. Dieses mehr ‚gefühlte’ als wissenschaftlich erwiesene Vorwissen haben wir im Rahmen eines Hauptseminars zur Geschichte des Mittelalters im Herbst 2017 gründlich hinterfragt. Ausgangspunkt war die Ausstellung „Richard Löwenherz“, die im September am Historischen Museum der Pfalz in Speyer eröffnet wurde. Ein Seminar zum Thema führte uns auf die Spuren der im Museum gezeigten Objekte, von dort auf die Spuren der Menschen im Umfeld des berühmten Königs von England

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

La Mise en scène du conte musical à l'école / Marcel Ley,...

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