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51.
Central venous catheterization (CVC), now a common procedure, has several major complications. We assessed their incidence in a prospective study of 1303 cannulations done in the intensive care unit or operating theatre. Chest radiographs were obtained to verify proper catheter placement and to detect pneumothorax. Complications were arterial puncture in 68 (5.2%) patients, arrhythmias in 21 (1.6%), cardiopulmonary arrest in 1 (0.1%), and pneumothorax in 5 (0.5%). The tip of the CVC was incorrectly located in 149 (11.2%). The chest radiograph was a valuable method for detecting complications of central venous catheterization. 相似文献
52.
M Ozkan C Kaymaz C Kirma A Civelek AR Cenal C Yakut U Deligonul 《Canadian Metallurgical Quarterly》1998,82(9):1066-1070
In this study we aimed to analyze, with reference to mitral regurgitation (MR), the incidence and predictors of left atrial (LA) thrombus and spontaneous echo contrast in patients with rheumatic valve disease before and after mitral valve replacement. The incidence of LA thrombus is known to be less in patients with MR. The impact of mitral valve replacement on this beneficial effect has not been studied in detail. The study included 169 consecutive patients (59 men and 110 women, average age 40 +/- 13 years) with rheumatic mitral valve disease who underwent transesophageal echocardiographic examination 1 to 3 days before and within 7 days (mean 4.0 +/- 1.3) after mitral valve replacement using mechanical prostheses in a single institution. The preoperative incidence of echocardiographic LA spontaneous echo contrast (SEC) was 1.1%, 30%, and 54%, and the incidence of thrombus was 1.1%, 13%, and 17% in the groups with MR, combined mitral stenosis + MR, and isolated mitral stenosis, respectively. In the MR group, SEC and thrombus incidence increased significantly after surgery. The independent predictors for postoperative thrombus development were atrial fibrillation, postoperative SEC, and preoperative thrombus. Thrombus recurred after surgery in 64% of 14 patients who had surgical thrombectomy. The presence of postoperative MR was associated with decreased risk of postoperative SEC and thrombus development. The interaction between MR and SEC and thrombus both before and after surgery provides further support for the protective effect of MR against LA thrombus formation. 相似文献
53.
Chueh Liu Changling Li Kazi Ahmed Zafer Mutlu Ilkeun Lee Francisco Zaera Cengiz S. Ozkan Mihrimah Ozkan 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(15)
Light‐weight graphite foam decorated with carbon nanotubes (dia. 20–50 nm) is utilized as an effective electrode without binders, conductive additives, or metallic current collectors for supercapacitors in aqueous electrolyte. Facile nitric acid treatment renders wide operating potentials, high specific capacitances and energy densities, and long lifespan over 10 000 cycles manifested as 164.5 and 111.8 F g?1, 22.85 and 12.58 Wh kg?1, 74.6% and 95.6% capacitance retention for 2 and 1.8 V, respectively. Overcharge protection is demonstrated by repetitive cycling between 2 and 2.5 V for 2000 cycles without catastrophic structural demolition or severe capacity fading. Graphite foam without metallic strut possessing low density (≈0.4–0.45 g cm?3) further reduces the total weight of the electrode. The thorough investigation of the specific capacitances and coulombic efficiencies versus potential windows and current densities provides insights into the selection of operation conditions for future practical devices. 相似文献
54.
Sequential multiple-laser-assisted polishing of free-standing CVD diamond substrates 总被引:4,自引:0,他引:4
Diamond, the best thermal conductor known, is the ultimate choice as a substrate material for the fabrication of denser, smaller and faster electronic packages. Consequently, in recent years, worldwide efforts have focused on the design of manufacturing transparent technologies for post-synthesis processing (polishing, planarization, metallization, die attach,, etc.) of diamond substrates In this study, a manufacturing-transparent, cost-effective, non-vacuum, laser-assisted coarse polishing technique for thick free-standing CVD diamond substrates was investigated [2]. The thickness of the substrates varied from 700 to 1000 μm, with the average grain size ranging from 150 to 200 μm. The average surface roughness (Ra) of the substrates, measured using contact surface profilometry, was between 20 and 30 μm. The substrates were initially irradiated with a Nd-YAG laser (λ = 532 nm) for coarse material removal, followed by an ArF excimer laser (λ = 193 nm) for finer surface finishing. Under optimized conditions, the average surface roughness (Rrma) was reduced from 25 to 5 μm with the Nd-YAG laser, and further to less than or equal to 1 μm with the excimer laser. The technique, which is the fastest processing technique known to the authors, is capable of polishing a 1 cm × 1 cm × 0.07 cm substrate in 50 s. 相似文献
55.
A. Ozkan Ozer Scott W. Hansen 《Mathematics of Control, Signals, and Systems (MCSS)》2011,23(1-3):199-222
We prove exact boundary controllability for the Rayleigh beam equation ${\varphi_{tt} -\alpha\varphi_{ttxx} + A\varphi_{xxxx} = 0, 0 < x < l, t > 0}$ with a single boundary control active at one end of the beam. We consider all combinations of clamped and hinged boundary conditions with the control applied to either the moment ${\varphi_{xx}(l, t)}$ or the rotation angle ${\varphi_{x}(l, t)}$ at an end of the beam. In each case, exact controllability is obtained on the space of optimal regularity for L 2(0, T) controls for ${T > 2l\sqrt{\frac{\alpha}{A}}}$ . In certain cases, e.g., the clamped case, the optimal regularity space involves a quotient in the velocity component. In other cases, where the regularity for the observed problem is below the energy level, a quotient space may arise in solutions of the observed problem. 相似文献
56.
57.
E. Unal I. Ozkan G. Cakmakci 《International Journal of Rock Mechanics and Mining Sciences》2001,38(2):7
In order to characterize the behavior of a main gate during retreating of longwall faces and to evaluate the performances of five different support types, including rock bolts and steel sets, a total of 21 convergence and 18 floor-heave stations were installed. Consequently, about 11,500 convergence and 7200 floor-heave data points were obtained over a period of 14 months. In order to simulate the behavior of a supported main gate roadway, a convergence model, represented by an exponential function, was developed on the basis of statistical analyses. In addition to the convergence model, convergence–velocity and convergence–acceleration models were also derived and interpreted in terms of gate road behavior. It was determined that the convergence depends on the loading region, the time, the location of the upper and lower longwall faces, the support type and pattern, and the static and dynamic support loads. Convergence–velocity and acceleration curves provide better means to interpret the performance of supports and gate roadway behavior. 相似文献
58.
Derya Ozkan Author Vitae 《Pattern recognition》2010,43(5):1717-1735
In this study, we propose a method for finding people in large news photograph and video collections. Our method exploits the multi-modal nature of these data sets to recognize people and does not require any supervisory input. It first uses the name of the person to populate an initial set of candidate faces. From this set, which is likely to include the faces of other people, it selects the group of most similar faces corresponding to the queried person in a variety of conditions. Our main contribution is to transform the problem of recognizing the faces of the queried person in a set of candidate faces to the problem of finding the highly connected sub-graph (the densest component) in a graph representing the similarities of faces. We also propose a novel technique for finding the similarities of faces by matching interest points extracted from the faces. The proposed method further allows the classification of new faces without needing to re-build the graph. The experiments are performed on two data sets: thousands of news photographs from Yahoo! news and over 200 news videos from TRECVid2004. The results show that the proposed method provides significant improvements over text-based methods. 相似文献
59.
60.
The pyrolysis of raw corn oil in the absence and presence of Lewis acids was carried out at 500°C. The catalytic effect of AlCl3 was better than that of FeCl3. The physico‐chemical properties of diesel‐like fuels produced by Lewis acid catalyzed are close to that of commercial diesel fuel. The diesel‐like fuels obtained from catalytic runs can be evaluated as diesel fuels. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献