Search results for "Equipment failure"
showing 10 items of 150 documents
Facepiece filtering respirators with exhalation valve should not be used in the community to limit SARS-CoV-2 diffusion.
2020
Comparison of two portable solid state detectors with an improved collimation and alignment device for mammographic x-ray spectroscopy.
2006
We describe a portable system for mammographic x-ray spectroscopy, based on a 2 X 2 X 1 mm3 cadmium telluride (CdTe) solid state detector, that is greatly improved over a similar system based on a 3 X 3 X 2 mm3 cadmium zinc telluride (CZT) solid state detector evaluated in an earlier work. The CdTe system utilized new pinhole collimators and an alignment device that facilitated measurement of mammographic x-ray spectra. Mammographic x-ray spectra acquired by each system were comparable. Half value layer measurements obtained using an ion chamber agreed closely with those derived from the x-ray spectra measured by either detector. The faster electronics and other features of the CdTe detecto…
"Photonic lantern" spectral filters in multi-core fibre
2012
Fiber Bragg gratings are written across all 120 single-mode cores of a multi-core optical Fiber. The Fiber is interfaced to multimode ports by tapering it within a depressed-index glass jacket. The result is a compact multimode "photonic lantern" filter with astrophotonic applications. The tapered structure is also an effective mode scrambler.
Negative differential resistance in carbon nanotube field-effect transistors with patterned gate oxide.
2010
We demonstrate controllable and gate-tunable negative differential resistance in carbon nanotube field-effect transistors, at room temperature and at 4.2 K. This is achieved by effectively creating quantum dots along the carbon nanotube channel by patterning the underlying, high-kappa gate oxide. The negative differential resistance feature can be modulated by both the gate and the drain-source voltage, which leads to more than 20% change of the current peak-to-valley ratio. Our approach is fully scalable and opens up a possibility for a new class of nanoscale electronic devices using negative differential resistance in their operation.
Self-phase modulation-based 2R regenerator including pulse compression and offset filtering for 42.6 Gbit/s RZ-33% transmission systems
2009
International audience; We report on the experimental and theoretical study of a self-phase-modulation-based regenerator at 42.6 Gbit/s with a return-to-zero 33% format. We point out some detrimental effects such as intrachannel interactions and Brillouin scattering. An efficient solution, relying on a self-phase-modulation-based pulse compressor in combination with the regenerator, is proposed to overcome these detrimental phenomena. The experimental demonstration shows the effectiveness of a wavelength-transparent regenerator at 42.6 Gbit/s with a sensitivity-improvement of more than 5 dB and an eye-opening improvement of 2.3 dB in a back-to-back configuration, as well as a 10 times maxim…
Soft proton exchanged channel waveguides in congruent lithium tantalate for frequency doubling
2010
We report on stable optical waveguides fabricated by soft-proton exchange in periodically-poled congruent lithium tantalate in the a-phase. The channel waveguides are characterized in the telecom wavelength range in terms of both linear properties and frequency doubling. The measurements yield a nonlinear coefficient of about 9.5pm/V, demonstrating that the nonlinear optical properties of lithium tantalate are left nearly unaltered by the process. (C) 2010 Optical Society of America
Microstructure alterations of rotary files after multiple simulated operative procedures.
2009
Aim: To assess morphological alterations of ProTaper rotary NiTi files before and after continuous use by scanning electron microscopy (SEM). Study Design: 30 root canals were chosen with an angle between 15 and 30º. Before starting to prepare the canals the files were observed microscopically using a scanning electronic microscope. The ProTaper sequence recommended by the manufacturer was used, with NaOCl as irrigant. The instruments were sterilised after every three canals were shaped. The instruments were observed with the same microscope after shaping each canal, until 30 root canals were shaped. The criteria used for checking the instruments were: blunt cutting edges, disruption of cut…
Recommendations of the European Cardiac Arrhythmia Society Committee on Device Failures and Complications
2006
Recommendations of the European Cardiac Arrhythmia Society Committee on Device Failures and Complications MASSIMO SANTINI,* JOHANNES BRACHMANN,† RICCARDO CAPPATO,‡ WYN DAVIES,§ JERONIMO FARRE,‖ SAMUEL LEVY,¶ AURELIO QUESADA,# RENATO P. RICCI,** EDWARD ROWLAND,†† NEIL SULKE‡‡ From *San Filipo Neri Hospital, Rome, Italy, †Klinikum Coburg, Germany, ‡Policlinico S. Donato, Milan, Italy, §St. Mary Hospital, London, UK, ‖Fundacion Jimenez Diaz, Madrid, Spain, ¶Hopital Nord des Bourrellys, Marseille, France, #Hospital General University of Valencia, Spain, **San Filippo Neri Hospital, ††St. George Medical School, London, UK, ‡‡Eastbourne General Hospital, Sussex, UK
Active-fixation coronary sinus pacing lead extraction: A hybrid approach
2012
Cardiac resynchronization therapy (CRT) can be considered as the standard treatment for patients suffering from heart failure (NYHA III–IV), severely reduced left ventricular (LV) function, and wide QRS complexes. Over the past years, the lead systems used to stimulate the left ventricle have evolved technically from epicardial approaches to a transvenous access accompanied by a significant reduction of procedure-related complication rates [1]. However, even today, LV dislodgement rates ranging 5–10% and the instability of thresholds over time remain the greatest challenges with transvenous LV leads in CRT. Therefore, a special LV lead utilizing active fixation (the Attain StarFix® active f…
Remote estimation of blood pulse pressure via temporal tracking of reflected secondary speckles pattern
2011
We present a novel technique for remote noncontact blood pulse pressure measurement. It is based on tracking both temporal and amplitude changes of reflected secondary speckle produced in human skin when illuminated by a laser beam. The implemented technique extracts the difference between the systolic and the diastolic blood pressure. Experimental results are presented showing good agreement when compared with conventional measurement methods.