Home About us Contact
|
Home About us Contact | ||
|
|
||
Various Devices (various + device)
Selected AbstractsTranscatheter Closure of Congenital Ventricular Septal Defects: Experience with Various DevicesJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 1 2003RAMESH ARORA D.M. Transcatheter closure of congenital ventricular septal defect (VSD) using various devices is gaining acceptance in selected cases of perimembranous and muscular defects, avoiding the inherent risks of cardiopulmonary bypass. The procedure was attempted in 137 patients having congenital defects using Rashkind Umbrella Device (RUD) in 29 patients, Amplatzer ventricular septal occluder (AVSO) in 107 patients, and Detachable Coil in one. All patients were selected using stringent criteria by detailed transthoracic echocardiography and/or transesophageal echocardiography. The location of VSD was perimembranous in 91 patients and was muscular trabecular in 46 patients. Seven patients had left ventricle (LV) to right atrium (RA) communication. Thirty-five patients with perimembranous and two with muscular VSD had aneurysm formation. The patients were 3 to 33 years old, and the diameter of VSD ranged from 3 to 12 mm. The pulmonary to systemic flow ratio was ,2:1 in 47 (34.3%) patients. The procedure was successful in 130 (94.8%) patients, with a success rate of 86.2% with RUD and 97.1% with AVSO. Residual shunt at 24 hours was seen in eight (32%) patients with RUD and in one patient (0.9%) with AVSO. Three (2.8%) developed transient bundle branch block, and two (1.9%) patients had complete heart block. New tricuspid stenosis and tricuspid regurgitation was observed in one patient each with AVSO. After immediate balloon dilatation, the mean pressure gradient across tricuspid valve decreased from 11 to 3 mmHg in the patient with tricuspid stenosis. On a follow-up of 1 to 66(mean 35.2 ± 10.7)months, the device was in position in all. None developed late conduction defect, aortic regurgitation, infective endocarditis, or hemolysis. At 9-month follow-up, the mean pressure gradient across the tricuspid valve was 3 mmHg in the patient with tricuspid stenosis. Complete occlusion of the shunt was achieved in 129 (99.2%) patients. One patient with RUD having persistent residual shunt underwent a second procedure with AVSO. Three out of 107 patients with AVSO had an unsuccessful procedure where the defect was perimembranous with a superior margin of defect less than 3 mm away from the aortic valve, and the specially designed perimembranous AVSO had to be retrieved because of hemodynamic compromise due to significant acute aortic regurgitation, whereas in all others, the defect was either ,3 mm away from the aortic valve or had aneurysm formation. All seven patients with LV to RA communication showed complete abolition of the shunt. Thus, in properly selected cases of perimembranous and muscular ventricular septal defects, the transcatheter closure is safe and efficacious using appropriate devices. The success rate is higher with AVSO compared with the previously used devices, as well as more successful for the muscular defects than those that are perimembranous in location. (J Interven Cardiol 2003;16:83,91) [source] Electrical and optical properties of CdS nanocrystalline semiconductorsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2006Shikha Tiwari Abstract II-VI semiconductor nanoparticles have recently attracted a lot of attention due to the possibility of their application in various devices. In the present study, chemical method has been used in synthesis of CdS nanoparticles and thiophenol was used as capping agent. X-ray diffraction studies of both samples were done. The dc conductivity of CdS increases at a lower rate or is approximately constant upto 500K and thereafter the conductivity increases at a rapid rate. Beyond Tc it is seen that the portion of the ,dc versus 1000/T is almost a straight line showing an Arrehenious behaviour. The dielectric constant of nanoparticles of CdS is found to be larger than the corresponding values of CdS crystals. It is clearly observed that at lower wavelengths nanocrystalline samples show a blue-shift. The three peaks of sample (S2), A, Band C can be ascribed to the transition from Cd-O complex donor formed by adsorbed oxygen to the valance band, Cd - excess acceptor and the surface states, respectively. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] THE ECONOMICS OF ACHIEVING COMPETITIVE BALANCE IN THE AUSTRALIAN FOOTBALL LEAGUE, 1897,2004ECONOMIC PAPERS: A JOURNAL OF APPLIED ECONOMICS AND POLICY, Issue 4 2004Ross Booth This paper summarises some key aspects of a theoretical and empirical analysis of whether various labour market devices and revenue-sharing rules used in the Victorian Football League/Australian Football League (VFL/AFL) since its inception in 1897 have increased competitive balance by reducing the inequality in the distribution of player talent between clubs. The history of labour market intervention and revenue sharing in the VFL/AFL is discussed, with six different periods between 1897 and 2004 identified for analysis. Fort and Quirk's (1995) model of US professional team sports leagues is used to analyse the effectiveness of the various devices that have been used in the VFL/AFL, but only after adapting the model to allow for VFL/AFL clubs being win maximisers (subject to a budget constraint) rather than profit maximisers. The various devices used by the VFL/AFL are assessed in terms of their likely impact on competitive balance, with some significantly different theoretical predictions than under profit maximisation. It is found that free agency results in a less equal distribution of player talent under win maximisation, whilst both gate sharing and increases in shared league-revenue tend to equalise playing strengths (which is not the case under profit maximisation). Moreover, the invariance principle, that the effect of a player draft will be undermined by the sale (and/or trade) of player talent, is found not necessarily to hold under win maximisation and can be reduced or eliminated with a team salary cap. Whether the trade of players and draft choices can undermine a player draft is also considered. The conclusion reached is that a player draft, a team salary cap, and revenue sharing is the combination most likely to succeed in achieving higher levels of competitive balance. The evidence of competitive balance in the VFL/AFL is consistent with these predictions. [source] Shape-prediction of 3D PTFE Microstructures Fabricated by Synchrotron Radiation AblationIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 2 2010Mitsuhiro Horade Non-member Abstract This article describes the calculation of the predictions of the deformed shapes of three-dimensional polytetrafluoroethylene (PTFE) microstructures fabricated by direct etching with a synchrotron radiation (SR) light source. As PTFE is a remarkable material, there is a lot of expectation regarding its applications in various devices. We did research on establishing a highly accurate three-dimensional technology for microfabricating PTFE by using an SR-light source because we aimed at applying this material in future devices. We built a shape-prediction technique as part of this research. Since this technique had the advantage of predicting shapes without experimentation, both fabrication time and cost could be reduced. It is also a useful technique for investigating and clarifying processing mechanisms. We compared structures fabricated in an experiment and the shapes computed with shape-prediction. The shape-prediction results were mostly in agreement with those from the experiment. As PTFE demonstrated excellent material characteristics, especially in its resistance to chemicals, it should be possible to use it in the fabrication of micro total analysis systems (µ-TAS) for biomedical applications. We expect that these applications will benefit from (based on) the designs which are predicted utilizing this calculation method. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Transcatheter Closure of Congenital Ventricular Septal Defects: Experience with Various DevicesJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 1 2003RAMESH ARORA D.M. Transcatheter closure of congenital ventricular septal defect (VSD) using various devices is gaining acceptance in selected cases of perimembranous and muscular defects, avoiding the inherent risks of cardiopulmonary bypass. The procedure was attempted in 137 patients having congenital defects using Rashkind Umbrella Device (RUD) in 29 patients, Amplatzer ventricular septal occluder (AVSO) in 107 patients, and Detachable Coil in one. All patients were selected using stringent criteria by detailed transthoracic echocardiography and/or transesophageal echocardiography. The location of VSD was perimembranous in 91 patients and was muscular trabecular in 46 patients. Seven patients had left ventricle (LV) to right atrium (RA) communication. Thirty-five patients with perimembranous and two with muscular VSD had aneurysm formation. The patients were 3 to 33 years old, and the diameter of VSD ranged from 3 to 12 mm. The pulmonary to systemic flow ratio was ,2:1 in 47 (34.3%) patients. The procedure was successful in 130 (94.8%) patients, with a success rate of 86.2% with RUD and 97.1% with AVSO. Residual shunt at 24 hours was seen in eight (32%) patients with RUD and in one patient (0.9%) with AVSO. Three (2.8%) developed transient bundle branch block, and two (1.9%) patients had complete heart block. New tricuspid stenosis and tricuspid regurgitation was observed in one patient each with AVSO. After immediate balloon dilatation, the mean pressure gradient across tricuspid valve decreased from 11 to 3 mmHg in the patient with tricuspid stenosis. On a follow-up of 1 to 66(mean 35.2 ± 10.7)months, the device was in position in all. None developed late conduction defect, aortic regurgitation, infective endocarditis, or hemolysis. At 9-month follow-up, the mean pressure gradient across the tricuspid valve was 3 mmHg in the patient with tricuspid stenosis. Complete occlusion of the shunt was achieved in 129 (99.2%) patients. One patient with RUD having persistent residual shunt underwent a second procedure with AVSO. Three out of 107 patients with AVSO had an unsuccessful procedure where the defect was perimembranous with a superior margin of defect less than 3 mm away from the aortic valve, and the specially designed perimembranous AVSO had to be retrieved because of hemodynamic compromise due to significant acute aortic regurgitation, whereas in all others, the defect was either ,3 mm away from the aortic valve or had aneurysm formation. All seven patients with LV to RA communication showed complete abolition of the shunt. Thus, in properly selected cases of perimembranous and muscular ventricular septal defects, the transcatheter closure is safe and efficacious using appropriate devices. The success rate is higher with AVSO compared with the previously used devices, as well as more successful for the muscular defects than those that are perimembranous in location. (J Interven Cardiol 2003;16:83,91) [source] Cryogen spray cooling: Effects of droplet size and spray density on heat removalLASERS IN SURGERY AND MEDICINE, Issue 2 2001Brian M. Pikkula BS Abstract Background and Objective Cryogen spray cooling (CSC) is an effective method to reduce or eliminate non-specific injury to the epidermis during laser treatment of various dermatological disorders. In previous CSC investigations, fuel injectors have been used to deliver the cryogen onto the skin surface. The objective of this study was to examine cryogen atomization and heat removal characteristics of various cryogen delivery devices. Study Design/Materials and Methods Various cryogen delivery device types including fuel injectors, atomizers, and a device currently used in clinical settings were investigated. Cryogen mass was measured at the delivery device output orifice. Cryogen droplet size profiling for various cryogen delivery devices was estimated by optically imaging the droplets in flight. Heat removal for various cryogen delivery devices was estimated over a range of spraying distances by temperature measurements in an skin phantom used in conjunction with an inverse heat conduction model. Results A substantial range of mass outputs were measured for the cryogen delivery devices while heat removal varied by less than a factor of two. Droplet profiling demonstrated differences in droplet size and spray density. Conclusions Results of this study show that variation in heat removal by different cryogen delivery devices is modest despite the relatively large difference in cryogen mass output and droplet size. A non-linear relationship between heat removal by various devices and droplet size and spray density was observed. Lasers Surg. Med. 28:103,112, 2001. © 2001 Wiley-Liss, Inc. [source] High-frequency scalable compact modelling of Si RF-CMOS technologyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2008Antonios Bazigos Abstract The aggressive downscaling of CMOS technologies offers record transit frequencies well above 100 GHz. Efficient RF circuit design, employing such technologies, demands non-linear, scalable compact models with high accuracy up to high frequencies. EKV3 is an advanced MOSFET model, based on charge sheet theory, that meets such demands. Within this paper, the model is validated against DC and RF measurements up to 30 GHz, for various devices of a modern 180 nm CMOS technology. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Helikite aerial photography , a versatile means of unmanned, radio controlled, low-altitude aerial archaeologyARCHAEOLOGICAL PROSPECTION, Issue 2 2009Geert J. J. Verhoeven Abstract During the past 100 years, various devices have been developed and applied in order to acquire archaeologically useful aerial imagery from low altitudes (e.g. balloons, kites, poles). This paper introduces Helikite aerial photography (HAP), a new form of close range aerial photography suitable for site or defined area photography, based on a camera suspended from a Helikite: a combination of both a helium balloon and kite wings. By largely overcoming the drawbacks of conventional kite- and balloon-based photography, HAP allows for a very versatile, remotely controlled approach to low-altitude aerial photography (LAAP). In addition to a detailed outline of the whole HAP system, its working procedure and possible improvements, some of the resulting imagery is shown to demonstrate the usefulness of HAP for several archaeological applications. Copyright © 2009 John Wiley & Sons, Ltd. [source] Cooling Device for Bradycardia Based on Peltier Element for Accurate Anastomosis of Off-Pump Coronary Artery Bypass GraftingARTIFICIAL ORGANS, Issue 10 2002Yukio Kuniyoshi Abstract: Upon introducing off-pump coronary artery bypass grafting (CABG), the indications for CABG were expanded to include patients who previously had no operative indications. For accurate anastomosis, various devices and methods have been developed. Bradycardia is easily induced by drug administration. However, this method of achieving bradycardia also has adverse effects on cardiac function. We have developed a new device to decrease the heart rate by regional cooling of the sino-atrial node. The new device is incorporated with Peltier's element, which uses an electric charge to create a temperature gradient on both of its surfaces. In terms of the cooling ability of this device, its cooling surface is chilled from 25°C to 0°C within 30 s. During in vivo animal experiments, this device has been shown to decrease the myocardial temperature around the sino-atrial node to 15°C and suppress sino-atrial node activity, resulting in bradycardia to 60 beats/min level. In summary, the simple and easily applicable device for local cooling in combination with the application of diltiazem for effective heart rate reduction may be very helpful for the surgeon and may avoid disadvantages for critically ill patients. [source] Diffusion properties of transurethral intraprostatic injectionBJU INTERNATIONAL, Issue 9 2004Mark K. Plante OBJECTIVES To evaluate the location and extent of diffusion that occurs when liquid is injected transurethrally into the prostate gland, by correlating real-time fluoroscopy and gross pathology, and to quantify the variables that influence intraprostatic diffusion during chemoablation of the prostate. MATERIALS AND METHODS A solution of diatrizoate meglumine (HypaqueTM, Nycomed, Princeton, NJ) gentamicin and methylene-blue dye (HGM) was injected transurethrally into the prostate in six dogs, using a passive-deflection needle injection system. The intraprostatic diffusion characteristics were evaluated during each injection using real-time C-arm fluoroscopy, and following each injection by gross examination of methylene blue staining within the prostatic tissues. HGM back-flow into the urethra at the time of injection was assessed by measuring gentamicin levels in the collected bladder irrigant after each injection, using a standard dilution formula. RESULTS There was variability in the intraprostatic diffusion both fluoroscopically and grossly. The needle occasionally assumed a straighter trajectory than its intended curve. Intraprostatic diffusion was detected in 12 of 36 injections (33%). Using standard manipulations of various devices increased the intraprostatic diffusion in these injections to almost 80%. There was less intraprostatic diffusion when the injection resistance was either extremely high or absent. There was no extraprostatic extravasation of HGM beyond the prostatic capsule. CONCLUSION Current methods of transurethral intraprostatic injection are variable for both the diffusion of HGM solution and in needle deployment. The gross diffusion patterns with the HGM solution were consistent with the diffusion patterns documented in our previous research using absolute ethanol. These and other factors may partly explain the variability of the lesions produced with ethanol injection. Therefore, more research is needed to further elucidate the diffusion characteristics of solutions injected intraprostatically using the transurethral approach. [source] Review Article: Ocular blood flow assessment using continuous laser Doppler flowmetryACTA OPHTHALMOLOGICA, Issue 6 2010Charles E. Riva Acta Ophthalmol. 2010: 88: 622,629 Abstract. This article describes the technique of continuous laser Doppler flowmetry (LDF) as applied to the measurement of the flux of red blood cells in the optic nerve head, iris and subfoveal choroid. Starting with the exposition of the physical principles underlying LDF, we first describe the various devices developed to perform LDF in these vascular beds. We then discuss the clinical protocols, blood flow parameters, calibration procedures, reproducibility and limitations of the LDF technique. Various problems still need to be solved in order to bring to light the full potential of LDF in the assessment of microcirculatory haemodynamics. [source] | |||||||||||||