Search results for "Equipment failure"
showing 10 items of 150 documents
Feasibility of cuff-free measurement of systolic and diastolic arterial blood pressure
2011
We validated a prototype cuff-free device for noninvasive estimation of blood pressure (BP). The system assumed a linear relation between BP values and the inverse of arterial blood pulse transit time, measured as time interval between the R wave on the electrocardiograph and the onset of the peripheral pulse wave on a finger plethysmogram. Thirty-three healthy subjects were analyzed at rest and during increasing stress exercise. To estimate subject-specific linear model parameters, the system was calibrated ad personam with reference to BP measures obtained by a cuff sphygmomanometer. High correlation values (R2= 0.89 and 0.78 for systolic and diastolic BP, respectively) and differences co…
Implantation Strategy of the Atrial Dipole Impacts Atrial Sensing Performance of Single Lead VDD Pacemakers
2002
WIEGAND, U.K.H., et al.: Implantation Strategy of the Atrial Dipole Impacts Atrial Sensing Perfor-mance of Single Lead VDD Pacemakers. Intermittent atrial undersensing is observed in a considerable percentage of patients with single lead VDD pacemakers. Analyzing the 2-year data of the Saphir Multicenter Follow-Up Study, the authors investigated predictors for the occurrence of undersensing. The study included 194 patients with high degree AV block who received a VDD pacemaker system with an identical sensing amplifier. Placement strategy of the atrial dipole was left to the discretion of the implanting physician. At the final position, atrial potential amplitudes were measured during deep …
Analysis of Fifty-Six Cochlear Implant Device Failures
2008
<i>Objective:</i> Our aim was to present a failure analysis after cochlear implant revision surgery in a large series of children and adults and to assess the outcome and audiologic performance. <i>Methods:</i> Fifty-six cochlear implant failures that occurred in 422 devices implanted between 1990 and 2007 at the Department of Otolaryngology, Head and Neck Surgery at the University of Mainz, Germany, were retrospectively analyzed. The causes of failure were reviewed evaluating the individual history, telemetric and intraoperative findings and manufacturer’s investigation reports. <i>Results:</i> We performed 56 surgical revisions in a series of 422 consec…
Reliability of cochlear implants.
2005
Background The long-term reliability of cochlear implants over time is an important issue for patients and cochlear implant teams. The calculation of cumulative survival rates including all hard failures of cochlear implants is suitable to report objectively about cochlear implant reliability. Methods This is a report of 192 cochlear implants from different manufacturers in adults (n = 58) and children (n = 134). Results The overall cumulative implant survival rate was 91.7% for a period of 11 years. The main reasons for hard failures were design errors of the products and direct or indirect trauma to the cochlea implant site (especially in children) with consecutive breaks of the implant b…
Clinical validation of embryo culture and selection by morphokinetic analysis: a randomized, controlled trial of the EmbryoScope.
2014
Objective To determine whether incubation in the integrated EmbryoScope time-lapse monitoring system (TMS) and selection supported by the use of a multivariable morphokinetic model improve reproductive outcomes in comparison with incubation in a standard incubator (SI) embryo culture and selection based exclusively on morphology. Design Prospective, randomized, double-blinded, controlled study. Setting University-affiliated private in vitro fertilization (IVF) clinic. Patient(s) Eight hundred forty-three infertile couples undergoing intracytoplasmic sperm injection (ICSI). Intervention(s) No patient intervention; embryos cultured in SI with development evaluated only by morphology (control …
Practical strategies for stable operation of HFF-QCM in continuous air flow
2013
Currently there are a few fields of application using quartz crystal microbalances (QCM). Because of environmental conditions and insufficient resolution of the microbalance, chemical sensing of volatile organic compounds in an open system was as yet not possible. In this study we present strategies on how to use 195 MHz fundamental quartz resonators for a mobile sensor platform to detect airborne analytes. Commonly the use of devices with a resonant frequency of about 10 MHz is standard. By increasing the frequency to 195 MHz the frequency shift increases by a factor of almost 400. Unfortunately, such kinds of quartz crystals tend to exhibit some challenges to obtain a reasonable signal-to…
Waveguiding properties of a photonic crystal fiber with a solid core surrounded by four large air holes
2009
The polarization-dependent guiding properties of a hexagonal-lattice photonic crystal fiber with a solid-core surrounded by four large air holes are investigated. The appearance of a polarization dependent cutoff frequency, together with several parameters as the birefringence, the modal effective area, the group velocity dispersion and the polarization dependent loss are analyzed. A collection of fibers with different structural parameters were fabricated and characterized. An effective anti-guide structure from at least 450 nm to 1750 nm, a polarizing fiber with a polarization dependent loss of 16 dB/m at 1550 nm, and an endlessly singlemode polarization-maintaining fiber with group biref…
A Refractive Index Sensor Based on the Resonant Coupling to Cladding Modes in a Fiber Loop
2013
We report an easy-to-build, compact, and low-cost optical fiber refractive index sensor. It consists of a single fiber loop whose transmission spectra exhibit a series of notches produced by the resonant coupling between the fundamental mode and the cladding modes in a uniformly bent fiber. The wavelength of the notches, distributed in a wavelength span from 1,400 to 1,700 nm, can be tuned by adjusting the diameter of the fiber loop and are sensitive to refractive index changes of the external medium. Sensitivities of 170 and 800 nm per refractive index unit for water solutions and for the refractive index interval 1.40-1.442, respectively, are demonstrated. We estimate a long range resolut…
Multioctave midinfrared supercontinuum generation in suspended-core chalcogenide fibers
2014
An As2S3 fiber-based supercontinuum source that covers 3500 nm, extending from near visible to the midinfrared, is successfully reported by using a 200-fs-pulsed pump with nJ-level energy at 2.5 μm. The main features of our fiber-based source are two-fold. On the one hand, a low-loss As2S3 microstructured optical fiber has been fabricated, with typical attenuation below 2 dB/m in the 1-4 μm wavelength range. On the other hand, a 20-mm-long microstructured fiber sample is sufficient to enable a spectral broadening, spreading from 0.6 to 4.1 μm in a 40 dB dynamic range.
Microstructured chalcogenide optical fibers from As2S3 glass: towards new IR broadband sources
2010
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