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271.
Surface normal overlap: a computer-aided detection algorithm with application to colonic polyps and lung nodules in helical CT 总被引:1,自引:0,他引:1
Paik DS Beaulieu CF Rubin GD Acar B Jeffrey RB Yee J Dey J Napel S 《IEEE transactions on medical imaging》2004,23(6):661-675
We developed a novel computer-aided detection (CAD) algorithm called the surface normal overlap method that we applied to colonic polyp detection and lung nodule detection in helical computed tomography (CT) images. We demonstrate some of the theoretical aspects of this algorithm using a statistical shape model. The algorithm was then optimized on simulated CT data and evaluated using a per-lesion cross-validation on 8 CT colonography datasets and on 8 chest CT datasets. It is able to achieve 100% sensitivity for colonic polyps 10 mm and larger at 7.0 false positives (FPs)/dataset and 90% sensitivity for solid lung nodules 6 mm and larger at 5.6 FP/dataset. 相似文献
272.
A new expansion for the signal-flowgraph determinant is presented, which gives the complete graph determinant in terms of the subgraph determinants and the loop gains. This expansion is useful for the evaluation of the determinant when the signal flowgraph is complicated and when there are many nontouching loops. 相似文献
273.
A study of 84 patients who were diagnosed with epididymo-orchitis between July 1987 and September 1993 is presented. Brucellosis was a complication in 14 cases (17%). All 14 cases had elevated agglutination titers. Brucella blood culture was found to be positive in 4 of 14 cases (28.5%). Standard therapy regime (streptomycin plus tetracycline) was effective in 13 of 14 (93%) cases. 相似文献
274.
Commercialization of reliable vibratory micromachined gyroscopes for high-volume applications has proven to be extremely challenging, primarily due to the high sensitivity of the dynamical system response to fabrication and environmental variations. This paper reports a novel micromachined gyroscope with two degrees-of-freedom (DOF) sense-mode oscillator that provides inherent robustness against structural parameter variations. The 2-DOF sense-mode oscillator provides a frequency response with two resonant peaks and a flat region between the peaks, instead of a single resonance peak as in conventional gyroscopes. The device is nominally operated in the flat region of the sense-mode response curve, where the amplitude and phase of the response are insensitive to parameter fluctuations. Furthermore, the sensitivity is improved by utilizing dynamical amplification of oscillations in the 2-DOF sense-mode oscillator. Thus, improved robustness to variations in temperature, damping, and structural parameters is achieved, solely by the mechanical system design. Prototype gyroscopes were fabricated using a bulk-micromachining process, and the performance and robustness of the devices have been experimentally evaluated. With a 25 V dc bias and 3 V ac drive signal resulting in 5.8 /spl mu/m drive-mode amplitude, the gyroscope exhibited a measured noise-floor of 0.64/spl deg//s//spl radic/Hz over 50 Hz bandwidth in atmospheric pressure. The sense-mode response in the flat operating region was also experimentally demonstrated to be inherently insensitive to pressure, temperature, and dc bias variations. 相似文献
275.
Acar B Savelieva I Hemingway H Malik M 《Computer methods and programs in biomedicine》2000,63(2):123-131
Our studies deal with fully automatic measurement of heart rate variability (HRV) in short term electrocardiograms. Presently, all existing HRV analysis programs require user intervention for ectopic beat identification, especially of supraventricular ectopic beats (SVE). This makes the HRV measurement in large, e.g. epidemiological studies problematic. In this paper, we present a fully automatic algorithm for the discrimination of the ventricular (VE) and SVE ectopic beats from the normal QRS complexes suited for a reliable HRV analysis. The QRS identification is based on the template matching method. The ectopic beats are identified based on several morphological and timing properties of the electrocardiogram (ECG) signal. The method incorporates several approaches and makes HRV analysis of large numbers of electrocardiograms feasible. It uses the template matching for the basic morphology check of the QRS complex and the P-wave, the timing information to avoid unnecessary ectopic beat checks and to adjust thresholds and it also looks for a special QRS morphology, which is common in VEs. We used a testing set of 69 electrocardiograms selected from a large number of recordings. The selected ECGs contained abnormalities including ectopic beats, right branch bundle block, respiratory arrhythmia, blocked atrial extrasystole, high amplitude and wide T-waves. The evaluation of our method showed a specificity of 0.99, supraventricular ectopic beat sensitivity of 0.99 and ventricular ectopic beat sensitivity of 0.98. 相似文献
276.
Duygu Acar Irene Teresa Molina-Martínez Miguel Gómez-Ballesteros Manuel Guzmán-Navarro José Manuel Benítez-del-Castillo Rocío Herrero-Vanrell 《Contact lens & anterior eye》2018,41(1):93-96
Purpose
Artificial tears are widely used in the treatment of dry eye disease, although current formulations do not closely resemble natural tears. The purpose of this study was the design and characterization of a novel in situ gelling artificial tear formulation, containing both lipid and aqueous components, in order to resemble natural tears and replenish the tear film.Methods
Liposomes, containing phosphatidylcholine, cholesterol, vitamins A and E, were prepared by the thin-film hydration method. The aqueous phase of the formulation was comprised of gellan gum, hydroxypropyl methylcellulose, levocarnitine, electrolytes (sodium chloride and potassium chloride), trehalose, and borates. The artificial tear was characterized in terms of liposome size, pH, surface tension, and viscosity. In vitro tolerance studies were performed in a human epithelial carcinoma cell line (HeLa) and a murine macrophage cell line (J774). In vivo tolerance was assessed in rabbits.Results
Liposomes presented a unimodal distribution with a mean size of 200.1?±?4.4?nm. The resulting surface tension was 53.4?±?1.1?mN/m (at 33?°C) and the pH was 7.6?±?0.1. The viscosity of the formulation presented a mean value of 4.0?±?0.1?mPa?s within the shear rate interval of 200–1000?s?1 at 33?°C. Cell viability remained higher than 90% in both cell lines. No discomfort or clinical signs were observed in rabbits.Conclusions
The liposome-based and in situ gelling artificial tear formulation presented good tolerance and suitable properties for topical ophthalmic administration. It may be beneficial in the treatment of dry eye disease. 相似文献277.
Gülsüm Deveci Nilüfer Acar Tek 《Journal of the science of food and agriculture》2024,104(5):2551-2560
Nitrite, nitrate, and their salts are added to processed meat products to improve color, flavor, and shelf life and to lower the microbial burden. N-Nitrosamine compounds are formed when nitrosing agents (such as secondary nitrosamines) in meat products interact with nitrites and nitrates that have been added to the meat. With the consumption of such meat products, nitrosation reactions occur in the human body and N-nitrosamine formation occurs in the gastrointestinal tract. Despite the benefits nitrites and nitrates have on food, their tendency to create nitrosamines and an increase in the body's nitrous amine load presents health risks. The inclusion of nitrosamine compounds in possible and probable carcinogen classes according to the International Agency for Research on Cancer requires a re-examination of the literature review on processed meat products. This article evaluates the connections between various cancer types and nitrosamines found in processed meat products. © 2023 Society of Chemical Industry. 相似文献
278.
Coralie Schnebelen Stéphane Grégoire Bruno Pasquis Corinne Joffre Catherine P. Creuzot-Garcher Alain M. Bron Lionel Bretillon Niyazi Acar 《Lipids》2009,44(5):465-470
The purpose of this study was to determine whether dietary n-3 and n-6 PUFA may affect retinal PUFA composition and PGE1 and PGE2 production. Male Wistar rats were fed for 3 months with diets containing: (1) 10% eicosapentaenoic acid (EPA) and 7% docosahexaenoic acid (DHA), or (2) 10% γ-linolenic acid (GLA), or (3) 10% EPA, 7% DHA and 10% GLA, or (4) a balanced diet deprived of EPA, DHA, and GLA. The fatty acid composition of retinal phospholipids was determined by gas chromatography. Prostaglandin production was measured by enzyme immunoassay. When compared to rats fed the control diet, the retinal levels of DHA were increased in rats fed both diets enriched with n-3 PUFA (EPA + DHA and EPA + DHA + GLA diets) and decreased in those supplemented with n-6 PUFA only (GLA diet). The diet enriched with both n-6 and n-3 PUFA resulted in the greatest increase in retinal DHA. The levels of PGE1 and PGE2 were significantly increased in retinal homogenates of rats fed with the GLA-rich diet when compared with those of animals fed the control diet. These higher PGE1 and PGE2 levels were not observed in animals fed with EPA + DHA + GLA. In summary, GLA added to EPA + DHA resulted in the highest retinal DHA content but without increasing retinal PGE2 as seen in animals supplemented with GLA only. 相似文献
279.
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