1,372 research outputs found

    Electrohysterographic volume conductor modeling

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    A simulation model to study maternal hyperoxygenation during labor

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    To investigate the effect of maternal hyperoxygenation on fetal oxygenation and fetal heart rate decelerations during labor, using a simulation model. Design Use of a mathematical model that simulates feto–maternal hemodynamics and oxygenation, designed in Matlab R2012a. Setting Clinical and engineering departments in the Netherlands. Methods We simulated variable and late fetal heart rate decelerations, caused by uterine contractions with a different contraction interval. We continuously recorded oxygen pressure in different feto–placental compartments and fetal heart rate, during maternal normoxia and during hyperoxygenation with 100% oxygen. Main outcome measures Changes in oxygen pressure in the intervillous space, umbilical vein and arteries, fetal cerebral and microcirculation as well as fetal heart rate deceleration depth and duration. Results Maternal hyperoxygenation leads to an increase in fetal oxygenation: in the presence of variable decelerations, oxygen pressure in the intervillous space increased 9–10 mmHg and in the cerebral circulation 1–2 mmHg, depending on the contraction interval. In addition, fetal heart rate deceleration depth decreased from 45 to 20 beats per minute. In the presence of late decelerations, oxygen pressure in the intervillous space increased 7–10 mmHg and in the cerebral circulation 1–2 mmHg, depending on the contraction interval. The fetus benefited more from maternal hyperoxygenation when contraction intervals were longer. Conclusions According to the simulation model, maternal hyperoxygenation leads to an increase in fetal oxygenation, especially in the presence of variable decelerations. In addition, in the presence of variable decelerations, maternal hyperoxygenation leads to amelioration of the fetal heart rate pattern

    Diabetes, Diabetic Complications, and Fracture Risk

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    Diabetes and osteoporosis are both common diseases with increasing prevalences in the aging population. There is increasing evidence corroborating an association between diabetes mellitus and bone. This review will discuss the disease complications of diabetes on the skeleton, highlighting findings from epidemiological, molecular, and imaging studies in animal models and humans. Compared to control subjects, decreased bone mineral dens

    Indium phosphide based membrane photodetector for optical interconnects on silicon

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    We have designed, fabricated and characterized an InP-based membrane photodetector on an SOI wafer containing a Si-wiring photonic circuit. New results on RF characterization up to 20 GHz are presented. The detector fabrication is compatible with wafer scale processing steps, guaranteeing compatibility towards future generation electronic IC processing

    Increased maternal TSH and decreased maternal FT4 are associated with a higher operative delivery rate in low-risk pregnancies:A prospective cohort study

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    Background:  The increasing number of operative deliveries is a topic of major concern in modern obstetrics. Maternal thyroid function is of known influence on many obstetric parameters. Our objective was to investigate a possible relation between maternal thyroid function, and operative deliveries. Secondary aim was to explore whether thyroid function was related to specific reasons for operative deliveries. Methods:  In this prospective cohort study, low-risk Caucasian women, pregnant of a single cephalic fetus were included. Women with known auto-immune disease, a pre-labour Caesarean section, induction of labour, breech presentation or preterm delivery were excluded. In all trimesters of pregnancy the thyroid function was assessed. Differences in mean TSH and FT4 were assessed using t-test. Mean TSH and FT4 levels for operative deliveries were determined by one way ANOVA. Repeated measurement analyses were performed (ANOVA), adjusting for BMI, partiy, maternal age and gestational age at delivery. Results:  In total 872 women were included, of which 699 (80.2 %) had a spontaneous delivery. At 36 weeks gestation women who had an operative delivery had a significantly higher mean TSH (1.63mIU/L versus 1.46mIU/L, p = 0.025) and lower mean FT4 (12.9pmol/L versus 13.3pmol/L, p = 0.007)) compared to women who had a spontaneous delivery. Mean TSH was significantly higher (p = 0.026) and mean FT4 significantly lower (p = 0.030) throughout pregnancy for women with an operative delivery due to failure to progress in second stage of labour, compared to women with a spontaneous delivery or operative delivery for other reasons. Conclusion:  Increased TSH and decreased FT4 seem to be associated with more operative vaginal deliveries and Caesarean sections. After adjusting for several confounders the association remained for operative deliveries due to failure to progress in second stage of labour, possibly to be explained by less efficient uterine action

    Relationship of promising methods in the detection of anthracycline-induced cardiotoxicity in breast cancer patients

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    Purpose\ud It remains challenging to identify patients at risk of anthracycline-induced cardiotoxicity. To better understand the different risk-stratifying approaches, we evaluated 123I-metaiodobenzylguanidine (123I-mIBG) scintigraphy and its interrelationship with conventional echocardiography, 2D strain imaging and several biomarkers.\ud \ud Methods\ud We performed 123I-mIBG scintigraphy, conventional and strain echocardiography and biomarker (NT-proBNP, TNF-α, galectin-3, IL-6, troponin I, ST-2 and sFlt-1) assessment in 59 breast cancer survivors 1 year after anthracycline treatment. Interobserver and intermethod variability was calculated on planar and SPECT 123I-mIBG scintigraphy, using the heart/mediastinum (H/M) ratio and washout (WO). Pearson’s r and multivariate analyses were performed to identify correlations and independent predictors of 123I-mIBG scintigraphy results.\ud \ud Results\ud Delayed planar anterior whole-heart ROI (WH) H/M ratios and WO were the most robust 123I-mIBG parameters. Significant correlations were observed between 123I-mIBG parameters and several conventional echo parameters, global longitudinal and radial strain (GLS and GRS) and galectin-3. The highest Pearson’s r was observed between delayed H/M ratio and GRS (Pearson’s r 0.36, p = 0.01). Multivariate analysis showed that GRS was the only independent predictor of the delayed WH H/M ratio (p = 0.023).\ud \ud Conclusion\ud The delayed planar H/M ratio is the most robust 123I-mIBG parameter. It correlates with several conventional echocardiographic parameters, GLS, GRS and galectin-3. Of these, only GRS predicts the H/M ratio

    Earth Through the Eyes of NAPA-1: Commissioning Results and the Next Steps in CubeSat Earth Observation

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    Disruptive CubeSat technology has brought scientific missions within reach that were previously only achievable through larger spacecraft. Satellite Earth Observation is now the new frontier for governments, private industry, and academia. With the recent launch of the Napa-1 satellite the Royal Thai Airforce (RTAF) has joined the ranks by having its first ever Earth Observation CubeSat in space. Its design, launch, early operations (LEOPS), and commissioning have been carried out by ISISpace, supporting the market’s need for imagery from space. Napa-1, meaning firmament in Thai, is a 6U CubeSat with the Gecko Imager from SCS Space as its primary payload, capable of taking RGB snapshot images with a 39-meter ground sampling distance (GSD) from 500 km altitude. In addition, the TriScape camera from Simera Sense flies onboard as an in-orbit technology demonstrator and is capable of delivering high-quality images with a GSD of 5 meter in the RGB bands. With well over 200 images taken by the primary payload this paper will look back on this exciting first period of Napa-1’s operational life and proudly present the very first images taken by the satellite and the lessons learnt throughout this turnkey mission. With that many images taken and that much data generated, the implemented onboard- and on ground data handling systems have been put to the test. ISISpace has made use of KUBOS’ Major Tom for command and control and having integrated a low-level processing tool, also for image data preview and delivery. Insight is provided into the systems and tools in place for image target planning, image acquisition, satellite command and control, and data delivery to the customer. How is it ensured targets are successfully captured? How is the usefulness of the image data efficiently validated? Subsequently, how is knowledge transfer to the customer accomplished to ensure successful routine operations? ISISpace will share the valuable lessons learnt from the mission planning, data handling, operations, and training points of view and show relevant in-orbit data on, for example, attitude behavior and temperature. In parallel, ISISpace has taken the next step in CubeSat Earth observation by using Napa-1 as a baseline while accommodating larger data streams and leveraging a higher level of automation. Together with the companies Simera Sense and Pinkmatter Solutions, multispectral images with automated on ground data processing (L0 up to L3) are to be delivered by the follow-up mission, Napa-2, to be launched in the summer of 2021. Details on this mission, including a further outlook at how CubeSat imagery and on ground processing will be shaped in the next few years will be provided

    High-performance InP-based photodetector in an amplifier layer stack on semi-insulating substrate

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    A waveguide photodetector (PD) based on semi-insulating (SI) indium phosphide (InP) was simulated, designed, and fabricated. The layer stack for this PD was optimized for use as an optical amplifier or laser and it can be combined with the passive components. By using an SI substrate and deep etching, a small, efficient, and high-speed PD was made, which allows for easy integration of source, detector, and passive optical components on a single chip. A 3-dB bandwidth of 35 GHz and 0.25 A/W external radio-frequency reponsivity is measured at 1.55-mum wavelength for a 1.5-mum-wide and 30-mum-long waveguide PD at -4-V bias voltage. The polarization dependence in the responsivity is less than 0.27 d
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