91 research outputs found
The kinematics of the swing phase obtained from accelerometer and gyroscope measurements
The kinematics needed to calculate the knee moment during the initial swing phase were obtained from a set of eight leg-mounted uni-axial accelerometers and two gyroscopes. The angular and linear accelerations of shank and thigh were calculated from the signals of two accelerometers mounted on each of the leg segments directed tangentially and radially to the movement. The angular velocities of shank and thigh were measured by the gyroscopes. The absolute angles of shank and thigh were obtained by integration of the gyroscope signal plus an added offset angle, estimated from radial and tangential accelerometer signals registered while standing. Movement was assumed to be in the saggital plane. The accuracy of the quantities found from the leg mounted sensors was calculated in terms of correlation and the RMS error by comparing against measurements obtained by a VICONTM system. The results were indistinguishable. The system was later applied in research measurement
Collaborative Knowledge Acquisition and Explorationin Technology Search
This article is about technology search as an example of a knowledge acquisition task in industry. Technology search is about finding technology related information in structured as well as unstructured sources. This information is needed to support optimal decision making in business processes. There are new opptortunities for technology search and challenges that need to be addressed. This article outlines some of these challenges and presents two concepts to address them in a search system
Imaging correlated wave functions of few-electron quantum dots: Theory and scanning tunneling spectroscopy experiments
We show both theoretically and experimentally that scanning tunneling
spectroscopy (STS) images of semiconductor quantum dots may display clear
signatures of electron-electron correlation. We apply many-body tunneling
theory to a realistic model which fully takes into account correlation effects
and dot anisotropy. Comparing measured STS images of freestanding InAs quantum
dots with those calculated by the full configuration interaction method, we
explain the wave function sequence in terms of images of one- and two-electron
states. The STS map corresponding to double charging is significantly distorted
by electron correlation with respect to the non-interacting case.Comment: RevTeX 4.0, 5 pages, 3 B/W figures, 1 table. This paper is based on
an invited talk presented by the authors at the 28th International Conference
on the Physics of Semiconductors, which was held 24-28 July 2006, in Vienna,
Austri
Enhanced Transmission in Rolled-up Hyperlenses utilizing Fabry-Pe\'rot Resonances
We experimentally demonstrate that the transmission though rolled-up
metal/semiconductor hyperlenses can be enhanced at desired frequencies
utilizing Fabry-P\'erot resonances. By means of finite difference time domain
simulations we prove that hyperlensing occurs at frequencies of high
transmission.Comment: 3 pages, 3 figure
EuroScore and IL-6 predict the course in ICU after cardiac surgery.
BACKGROUND
Despite modern advances in intensive care medicine and surgical techniques, mortality rates in cardiac surgical patients are still about 3%. Considerable efforts were made to predict morbidity and mortality after cardiac surgery. In this study, we analysed the predictive properties of EuroScore and IL-6 for mortality in ICU, prolonged postoperative mechanical ventilation, and prolonged stay in ICU.
METHODS
We enrolled 2972 patients undergoing cardiac surgery. The patients either underwent aortic valve surgery (AV), mitral valve surgery (MV), coronary artery bypass grafting (CABG), and combined operations of aortic valve and coronary artery bypass grafting (AV + CABG) or of mitral and tricuspid valve (MV + TV). Different laboratory and clinical parameters were analysed.
RESULTS
EuroScore as well as IL-6 were associated with increased mortality after cardiac surgery. Furthermore, a higher EuroScore and elevated levels of IL-6 were predictors for prolonged mechanical ventilation and a longer stay in ICU. Especially, highly significant elevated IL-6 levels and an increased EuroScore showed a strong association. Statistics suggested superiority when both parameters were combined in a single model.
CONCLUSION
Our results suggest that EuroScore and IL-6 are helpful in predicting the course in ICU after cardiac surgery, and therefore, the use of intensive care resources. Especially, the combination of highly elevated levels of IL-6 and EuroScore may prove to be excellent predictors for an unfortunate postoperative course in ICU
Gain in Three-Dimensional Metamaterials utilizing Semiconductor Quantum Structures
We demonstrate gain in a three-dimensional metal/semiconductor metamaterial
by the integration of optically active semiconductor quantum structures. The
rolling-up of a metallic structure on top of strained semiconductor layers
containing a quantum well allows us to achieve a three-dimensional superlattice
consisting of alternating layers of lossy metallic and amplifying gain
material. We show that the transmission through the superlattice can be
enhanced by exciting the quantum well optically under both pulsed or continuous
wave excitation. This points out that our structures can be used as a starting
point for arbitrary three-dimensional metamaterials including gain
Modulation of mammalian cell behavior by nanoporous glass
The introduction of novel bioactive materials to manipulate living cell behavior is a crucial topic for biomedical research and tissue engineering. Biomaterials or surface patterns that boost specific cell functions can enable innovative new products in cell culture and diagnostics. This study investigates the influence of the intrinsically nano-patterned surface of nanoporous glass membranes on the behavior of mammalian cells. Three different cell lines and primary human mesenchymal stem cells (hMSCs) proliferate readily on nanoporous glass membranes with mean pore sizes between 10 and 124 nm. In both proliferation and mRNA expression experiments, L929 fibroblasts show a distinct trend toward mean pore sizes >80 nm. For primary hMSCs, excellent proliferation is observed on all nanoporous surfaces. hMSCs on samples with 17 nm pore size display increased expression of COL10, COL2A1, and SOX9, especially during the first two weeks of culture. In the upside down culture, SK-MEL-28 cells on nanoporous glass resist the gravitational force and proliferate well in contrast to cells on flat references. The effect of paclitaxel treatment of MDA-MB-321 breast cancer cells is already visible after 48 h on nanoporous membranes and strongly pronounced in comparison to reference samples, underlining the material's potential for functional drug screening
4-channel 200 Gb/s WDM O-band silicon photonic transceiver sub-assembly
We demonstrate a 200G capable WDM O-band optical transceiver comprising a 4-element array of Silicon Photonics ring modulators (RM) and Ge photodiodes (PD) co-packaged with a SiGe BiCMOS integrated driver and a SiGe transimpedance amplifier (TIA) chip. A 4 x 50 Gb/s data modulation experiment revealed an average extinction ratio (ER) of 3.17 dB, with the transmitter exhibiting a total energy efficiency of 2 pJ/bit. Data reception has been experimentally validated at 50 Gb/s per lane, achieving an interpolated 10E-12 bit error rate (BER) for an input optical modulation amplitude (OMA) of -9.5 dBm and a power efficiency of 2.2 pJ/bit, yielding a total power efficiency of 4.2 pJ/bit for the transceiver, including heater tuning requirements. This electro-optic subassembly provides the highest aggregate data-rate among O-band RM-based silicon photonic transceiver implementations, highlighting its potential for next generation WDM Ethernet transceivers. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Integration of III-V light sources on a silicon photonics circuits by transfer printing
We report on the integration by transfer printing of III-V Fabry-Perot cavities on a silicon photonic circuit. We pre-process the III-V coupons on their native substrate, transfer print onto the target SOI, and post-process the printed coupons. We report light coupling into the photonic circuit
Charge Tunable GaAs Quantum Dots in a Photonic n-i-p Diode
In this submission, we discuss the growth of charge-controllable GaAs quantum dots embedded in an n-i-p diode structure, from the perspective of a molecular beam epitaxy grower. The QDs show no blinking and narrow linewidths. We show that the parameters used led to a bimodal growth mode of QDs resulting from low arsenic surface coverage. We identify one of the modes as that showing good properties found in previous work. As the morphology of the fabricated QDs does not hint at outstanding properties, we attribute the good performance of this sample to the low impurity levels in the matrix material and the ability of n- and p-doped contact regions to stabilize the charge state. We present the challenges met in characterizing the sample with ensemble photoluminescence spectroscopy caused by the photonic structure used. We show two straightforward methods to overcome this hurdle and gain insight into QD emission properties
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