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Sample records for ecg-gated axial scans

  1. Coronary Artery Stent Evaluation Using a Vascular Model at 64-Detector Row CT: Comparison between Prospective and Retrospective ECG-Gated Axial Scans

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    Suzuki, Shigeru; Furui, Shigeru; Kaminaga, Tatsuro; Miyazawa, Akiyoshi; Ueno, Yasunari; Konno, Kumiko [Teikyo University School of Medicine, Tokyo (Japan); Kuwahara, Sadatoshi; Mehta, Dhruv [Philips Electronics Japan, Ltd. Medical Systems, Tokyo (Japan)

    2009-06-15

    We wanted to evaluate the performance of prospective electrocardiogram (ECG)-gated axial scans for assessing coronary stents as compared with retrospective ECG-gated helical scans. As for a vascular model of the coronary artery, a tube of approximately 2.5-mm inner diameter was adopted and as for stents, three (Bx-Velocity, Express2, and Micro Driver) different kinds of stents were inserted into the tube. Both patent and stenotic models of coronary artery were made by instillating different attenuation (396 vs. 79 Hounsfield unit [HU]) of contrast medium within the tube in tube model. The models were scanned with two types of scan methods with a simulated ECG of 60 beats per minute and using display field of views (FOVs) of 9 and 18 cm. We evaluated the in-stent stenosis visually, and we measured the attenuation values and the diameter of the patent stent lumen. The visualization of the stent lumen of the vascular models was improved with using the prospective ECG-gated axial scans and a 9-cm FOV. The inner diameters of the vascular models were underestimated with mean measurement errors of -1.10 to -1.36 mm. The measurement errors were smaller with using the prospective ECG-gated axial scans (Bx-Velocity and Express2, p < 0.0001; Micro Driver, p = 0.0004) and a 9-cm FOV (all stents: p < 0.0001), as compared with the other conditions, respectively. The luminal attenuation value was overestimated in each condition. For the luminal attenuation measurement, the use of prospective ECG-gated axial scans provided less measurement error compared with the retrospective ECG-gated helical scans (all stents: p < 0.0001), and the use of a 9-cm FOV tended to decrease the measurement error. The visualization of coronary stents is improved by the use of prospective ECG-gated axial scans and using a small FOV with reduced blooming artifacts and increased spatial resolution.

  2. Bicuspid aortic valves: Diagnostic accuracy of standard axial 64-slice chest CT compared to aortic valve image plane ECG-gated cardiac CT

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    Murphy, David J., E-mail: david.murphy@st-vincents.ie [Department of Radiology, St Vincent' s University Hospital, Elm Park, Dublin 4 (Ireland); McEvoy, Sinead H., E-mail: s.mcevoy@st-vincents.ie [Department of Radiology, St Vincent' s University Hospital, Elm Park, Dublin 4 (Ireland); Iyengar, Sri, E-mail: sri.iyengar@nhs.net [Department of Radiology, Plymouth Hospitals NHS Trust, Plymouth Devon PL6 8DH (United Kingdom); Feuchtner, Gudrun, E-mail: Gudrun.Feuchtner@i-med.ac.at [Department of Radiology, Innsbruck Medical University, Anichstr. 35, A-6020 Innsbruck (Austria); Cury, Ricardo C., E-mail: r.cury@baptisthealth.net [Department of Radiology, Baptist Cardiac and Vascular Institute, 8900 North Kendall Drive, Miami, FL 33176 (United States); Roobottom, Carl, E-mail: carl.roobottom@nhs.net [Department of Radiology, Plymouth Hospitals NHS Trust, Plymouth Devon PL6 8DH (United Kingdom); Plymouth University Peninsula Schools of Medicine and Dentistry (United Kingdom); Baumueller, Stephan, E-mail: Hatem.Alkadhi@usz.ch [Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich (Switzerland); Alkadhi, Hatem, E-mail: stephan.baumueller@usz.ch [Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich (Switzerland); Dodd, Jonathan D., E-mail: jonniedodd@gmail.com [Department of Radiology, St Vincent' s University Hospital, Elm Park, Dublin 4 (Ireland)

    2014-08-15

    Objectives: To assess the diagnostic accuracy of standard axial 64-slice chest CT compared to aortic valve image plane ECG-gated cardiac CT for bicuspid aortic valves. Materials and methods: The standard axial chest CT scans of 20 patients with known bicuspid aortic valves were blindly, randomly analyzed for (i) the appearance of the valve cusps, (ii) the largest aortic sinus area, (iii) the longest aortic cusp length, (iv) the thickest aortic valve cusp and (v) valve calcification. A second blinded reader independently analyzed the appearance of the valve cusps. Forty-two age- and sex-matched patients with known tricuspid aortic valves were used as controls. Retrospectively ECG-gated cardiac CT multiphase reconstructions of the aortic valve were used as the gold-standard. Results: Fourteen (21%) scans were scored as unevaluable (7 bicuspid, 7 tricuspid). Of the remainder, there were 13 evaluable bicuspid valves, ten of which showed an aortic valve line sign, while the remaining three showed a normal Mercedes-Benz appearance owing to fused valve cusps. The 35 evaluable tricuspid aortic valves all showed a normal Mercedes-Benz appearance (P = 0.001). Kappa analysis = 0.62 indicating good interobserver agreement for the aortic valve cusp appearance. Aortic sinus areas, aortic cusp lengths and aortic cusp thicknesses of ≥3.8 cm{sup 2}, 3.2 cm and 1.6 mm respectively on standard axial chest CT best distinguished bicuspid from tricuspid aortic valves (P < 0.0001 for all). Of evaluable scans, the sensitivity, specificity, positive and negative predictive values of standard axial chest CT in diagnosing bicuspid aortic valves was 77% (CI 0.54–1.0), 100%, 100% and 70% respectively. Conclusion: The aortic valve is evaluable in approximately 80% of standard chest 64-slice CT scans. Bicuspid aortic valves may be diagnosed on evaluable scans with good diagnostic accuracy. An aortic valve line sign, enlarged aortic sinuses and elongated, thickened valve cusps are specific CT

  3. Evaluation of exposure dose reduction in multislice CT coronary angiography (MS-CTA) with prospective ECG-gated helical scan

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    Ota, Takamasa; Tsuyuki, Masaharu; Okumura, Miwa; Sano, Tomonari; Kondo, Takeshi; Takase, Shinichi

    2008-03-01

    A novel low-dose ECG-gated helical scan method to investigate coronary artery diseases was developed. This method uses a high pitch for scanning (based on the patient's heart rate) and X-rays are generated only during the optimal cardiac phases. The dose reduction was obtained using a two-level approach: 1) To use a 64-slice CT scanner (Aquilion, Toshiba, Otawara, Tochigi, Japan) with a scan speed of 0.35 s/rot. to helically scan the heart at a high pitch based on the patient's heart rate. By changing the pitch from the conventional 0.175 to 0.271 for a heart rate of 60 bpm, the exposure dose was reduced to 65%. 2) To employ tube current gating that predicts the timing of optimal cardiac phases from the previous cardiac cycle and generates X-rays only during the required cardiac phases. The combination of high speed scanning with a high pitch and appropriate X-ray generation only in the cardiac phases from 60% to 90% allows the exposure dose to be reduced to 5.6 mSv for patients with a heart rate lower than 65 bpm. This is a dose reduction of approximately 70% compared to the conventional scanning method recommended by the manufacturer when segmental reconstruction is considered. This low-dose protocol seamlessly allows for wide scan ranges (e.g., aortic dissection) with the benefits of ECG-gated helical scanning: smooth continuity for longitudinal direction and utilization of data from all cardiac cycles.

  4. Low-dose adaptive sequential scan for dual-source CT coronary angiography in patients with high heart rate: Comparison with retrospective ECG gating

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    Xu Lei, E-mail: leixu2001@hotmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Yang Lin, E-mail: anna7949@163.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Zhang Zhaoqi, E-mail: zhaoqi5000@vip.sohu.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Li Yu, E-mail: athen06@hotmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Fan Zhanming, E-mail: fanzm120@tom.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Ma Xiaohai, E-mail: maxi8238@gmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Lv Biao, E-mail: biao_lu2007@sina.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Yu Wei, E-mail: yuwei02@gmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China)

    2010-11-15

    Purpose: To explore feasibility of dual-source CT (DS-CT) prospective ECG-gated coronary angiography in patients with heart rate (HR) higher than 70 beat per minute (bpm), and evaluate image quality and radiation dose with comparison to retrospective ECG-gated spiral scan. Materials and methods: One hundred patients who underwent DS-CT coronary angiography (DS-CTCA) with mean HR higher than 70 bpm but below 110 bpm were enrolled in the study, 50 were scanned by adaptive sequential scan and another 50 were analyzed by retrospectively gated CT scan. The imaging quality of coronary artery segments in the two groups was evaluated using a four-point grading scale by two independent reviewers. Patient radiation dose was calculated by multiplying dose length product by conversion coefficient of 0.017. Results: There was no significant difference between the two groups for mean HR (p = 0.305), HR variability (p = 0.103), body mass index (p = 0.472), and scan length (p = 0.208). There was good agreement for image quality scoring between the two reviewers (Kappa = 0.72). Coronary evaluability of adaptive sequential scan was 99.7% (608 of 610 segments), while that of retrospective gated scan was 98.7% (614 of 622 segments), showing similar coronary evaluability (p = 0.061). Effective doses of adaptive sequential scan and retrospective gated scan were 5.1 {+-} 1.6 and 11.8 {+-} 4.5 mSv, respectively (p < 0.001), showing that adaptive sequential scan reduced radiation dose by 57% compared with that of retrospective gated scan. Conclusions: In patients with 70-110 bpm HR, DS-CTCA adaptive sequential scan shows similar image quality as retrospective ECG-gated spiral scan with 57% reduction of radiation dose.

  5. Comparison of 128-Slice Low-Dose Prospective ECG-Gated CT Scanning and Trans-Thoracic Echocardiography for the Diagnosis of Complex Congenital Heart Disease

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    Bu, Guilin; Miao, Ying; Bin, Jingwen; Deng, Sheng; Liu, Taowen; Jiang, Hongchun; Chen, Weiping

    2016-01-01

    Objective To compare prospective ECG-gated multi-slice computed tomography (MSCT) and trans-thoracic echocardiography (TTE) in the diagnosis of complex congenital heart disease (CHD). Methods This was a prospective study of consecutive patients with complex CHD (age ECG-gated 128-slice spiral CT in the week before surgery. Effective radiation dose (ED) was calculated from volume CT dose index (CTDIvol) and dose length product (DLP). Image quality (5-point scale) was assessed independently by two radiologists. Using surgical findings as the reference, the diagnostic capabilities of MSCT and TTE were compared. Results Thirty-five patients (19 males) aged 1.59±1.58 years (range, 3 days to 74 months) were included. CTDIvol, DLP and ED were 0.90±0.24 mGy, 12.9±4.7 mGy∙cm and 0.64±0.21 mSv (range, 0.358–1.196 mSv), respectively. Image quality score was 4.3±0.5, and all images met the diagnostic requirements. The sensitivity, specificity, positive predictive value, and negative predictive value for diagnosing CHD were 97.2%, 99.8%, 99.0%, and 99.5%, respectively, for MSCT, and 90.6%, 99.8%, 99.0%, and 98.4%, respectively, for TTE. MSCT not only had a higher sensitivity than TTE overall (97.2% vs. 90.6%; PECG-gated CT scanning has important clinical value in the diagnosis of complex CHD in children, complementing and extending the findings of TTE. PMID:27788237

  6. Contrast material and radiation dose reduction strategy for triple-rule-out cardiac CT angiography: feasibility study of non-ECG-gated low kVp scan of the whole chest following coronary CT angiography.

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    Kidoh, Masafumi; Nakaura, Takeshi; Nakamura, Shinichi; Namimoto, Tomohiro; Nozaki, Toshimitsu; Sakaino, Naritsugu; Harada, Kazunori; Yamashita, Yasuyuki

    2014-12-01

    Dedicated coronary computed tomography (CT) scan has been proven to be an accurate diagnostic modality in evaluating coronary artery disease. A second phase scan starting immediately after the coronary CT scan might enable visualization of the different vascular territories of the entire chest. To investigate the feasibility of a contrast material and radiation dose reduction triple-rule-out (TRO) CT angiography (CTA) protocol with serial non-ECG-gated low kVp scan of the whole chest, which utilizes a recirculated contrast agent. Thirty patients were scanned with the new TRO-CTA protocol; after the coronary scan with retrospective ECG-gating, non-ECG-gated whole-chest CTA was performed at 80 kVp to evaluate aortic arch (AAr) and pulmonary trunk (PT). Another 30 patients were scanned by our conventional TRO-CTA protocol at 120 kVp with retrospective ECG-gating. We compared the estimated effective dose (ED), contrast material (CM) dose, contrast-to-noise ratio (CNR) of the ascending aorta (AAo), and the rate of patients who could achieve adequate attenuation of the AAr and PT between the two protocols. The total ED of the new TRO-CTA protocol was 29.6% lower than that of the conventional protocol (P TRO-CTA protocol was significantly lower than in the conventional protocol (60.1 ± 9.6 mL vs. 91.8 ± 22.6 mL, P TRO-CTA protocol than with the conventional protocol (P 0.05). The new TRO-CTA protocol can reduce the total dose of radiation and the contrast dose and yield adequate vascular enhancement compared with the conventional protocol. © The Foundation Acta Radiologica 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  7. Identification and Assessment of Paradoxical Ventricular Wall Motion Using ECG Gated Blood Pool Scan - Comparison of cine Loop , Phase Analysis and Paradox Image -

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    Lee, Jae Tae; Kim, Gwang Weon; Lee, Kyu Bo; Chung, Byung Chun; Whang, Kee Suk; Chae, Sung Chul; Paek, Wee Hyun; Cheon, Jae Eun [Kyungpook National University School of Medicine, Daegu (Korea, Republic of); Lee, Hyong Woo; Chung, Jin Hong [Yeongnam National University College of Medicine, Daegu (Korea, Republic of)

    1990-07-15

    Sixty-four patients with paradoxical ventricular wall motion noticed both in angiocardiography or 2-dimensional echocardiography were assessed by ECG gated blood pool scan (GBPS). Endless cine loop image, phase and amplitude images and paradox image obtained by visual inspection of each cardiac beat or Fourier transformation of acquired raw data were investigated to determine the incremental value of GBPS with these processing methods for identification of paradoxical ventricular wall motion. The results were as follows:1) Paradoxical wall motions were observed on interventricular septum in 34 cases, left ventricular free wall in 26 and right ventricular wall in 24. Underlying heart diseases were is chemic (23 cases) valvular(9), congenital heart disease (12), cardiomyopathy (5), pericardial effusion(5), post cardiac surgery(3), corpulmonale (2), endocarditis (l) and right ventricular tumor(l). 2) Left ventricular ejection fractions of patients with paradoxical left ventricular wall motion were significantly lower than those with paradoxical septal motion (p <0.005). 3) The sensitivity of each processing methods for detecting paradoxical wall motion was 76.9% by phase analysis, 74.6% by endless cine loop mapping and 68.4% by paradox image manipulation respectively. Paradoxial motions visualized only in phase, paradox or both images were appeared as hypokinesia or akinesia in cine loop image. 4) All events could be identified by at least one of above three processing methods, however only 34 cases (48.4%) showed the paradoxical motions in all of the three images. By these findings, we concluded that simultaneous inspection of all above three processing methods-endless cine loop, phase analysis and paradox image is necessary for accurate identification and assessment of paradoxical ventricular wall motion when performing GBPS.

  8. ECG-gated HYPR reconstruction for undersampled CT myocardial perfusion imaging

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    Speidel, Michael A.; Van Lysel, Michael S.; Reeder, Scott B.; Supanich, Mark; Nett, Brian E.; Zambelli, Joseph; Chang, Su Min; Hsieh, Jiang; Chen, Guang-Hong; Mistretta, Charles A.

    2007-03-01

    In this study we develop a novel ECG-gated method of HYPR (HighlY constrained backPRojection) CT reconstruction for low-dose myocardial perfusion imaging and present its first application in a porcine model. HYPR is a method of reconstructing time-resolved images from view-undersampled projection data. Scanning and reconstruction techniques were explored using x-ray projections from a 50 sec contrast-enhanced axial scan of a 47 kg swine on a 64-slice MDCT system. Scans were generated with view undersampling factors from 2 to 10. A HYPR reconstruction algorithm was developed in which a fully-sampled composite image is generated from views collected from multiple cardiac cycles within a diastolic window. A time frame image for a heartbeat was produced by modifying the composite with projections from the cycle of interest. Heart rate variations were handled by automatically selecting cardiac window size and number of cycles per composite within defined limits. Cardiac window size averaged 35% of the R-R interval for 2x undersampling and increased to 64% R-R using 10x undersampling. The selected window size and cycles per composite was sensitive to synchrony between heart rate, gantry rate, and the view undersampling pattern. Temporal dynamics and perfusion metrics measured in conventional short-scan (FBP) images were well-reproduced in the undersampled HYPR time series. Mean transit times determined from HYPR myocardial time-density curves agreed to within 8% with the FBP results. The results indicate potential for an order of magnitude reduction in dose requirement per image in cardiac perfusion CT via undersampled scanning and ECG-gated HYPR reconstruction.

  9. 钙化积分扫描缩短冠脉CTA扫描范围及降低辐射量的作用%Effect of calcium scoring scan in reducing scan range and radiation dose in retrospectively ECG-gated CT coronary angiography

    Institute of Scientific and Technical Information of China (English)

    付维东; 龚建平; 宦坚; 张伟; 张博; 乔方

    2012-01-01

    Objective:To find out a way of reducing scan range in retrospectively ECG-gated CT coronary angiography in order to reduce the radiation dose. Methods: Forty consecutive patients were analyzed retrospectively. The scan range of CT coronary angiography derived respectively from the scout view and from the axial images of calcium scoring were compared. The former was assumed to be determined from 1cm under the trachea carina to 2cm under the inferior margin of the heart. The latter was performed by identifying the left anterior descending coronary artery and posterior descending coronary artery and adding lcm cranially and caudally. Effective radiation doses were calculated for CT coronary angiography using both scout view-derived and calcium scoring-derived scan range. Results: The calcium scoring-derived range was (10. 40+.0. 60)cm; while the scout view-derived range was (12. 5 ± 0. 94)cm which was significantly larger than that of using the calcium scoring-derived scan (t = 17. 31,P<0. 01). The average difference between them was (2. 09±0. 76)cm, corresponding to a radiation dose reduction of (1. 67 ±0. 72)mSv. After offsetting the dose given for the calcium scoring scan,the savings in radiation exposure when using a calcium scoring-derived instead of a scout view-derived scan range for CT coronary angiography -including the radiation dose of the calcium scoring scan and the test bolus scan- was (1. 25 + 0. 72)mSv (t=10. 92.P<0. 01) ,which accounted for a dose reduction of 9. 20%. Conclusion:Using the images from calcium scoring instead of the scout view to determine the scan range of contrast-unenhanced CT coronary angiography can effectively decrease the scan range and reduce the radiation dose significantly.%目的:探讨使用钙化积分扫描缩短增强扫描范围以降低后门控冠状动脉CTA检查辐射量的临床应用价值.方法:40例患者行冠脉钙化积分及冠脉CTA检查,其增强扫描的实际扫描范围根据钙化积分扫描图

  10. Fetal Electrocardiogram (fECG Gated MRI

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    Martyn N.J. Paley

    2013-08-01

    Full Text Available We have developed a Magnetic Resonance Imaging (MRI-compatible system to enable gating of a scanner to the heartbeat of a foetus for cardiac, umbilical cord flow and other possible imaging applications. We performed radiofrequency safety testing prior to a fetal electrocardiogram (fECG gated imaging study in pregnant volunteers (n = 3. A compact monitoring device with advanced software capable of reliably detecting both the maternal electrocardiogram (mECG and fECG simultaneously was modified by the manufacturer (Monica Healthcare, Nottingham, UK to provide an external TTL trigger signal from the detected fECG which could be used to trigger a standard 1.5 T MR (GE Healthcare, Milwaukee, WI, USA gating system with suitable attenuation. The MR scanner was tested by triggering rapidly during image acquisition at a typical fetal heart rate (123 beats per minute using a simulated fECG waveform fed into the gating system. Gated MR images were also acquired from volunteers who were attending for a repeat fetal Central Nervous System (CNS examination using an additional rapid cardiac imaging sequence triggered from the measured fECG. No adverse safety effects were encountered. This is the first time fECG gating has been used with MRI and opens up a range of new possibilities to study a developing foetus.

  11. Prevalence and clinical significance of incidental cardiac findings in non-ECG-gated chest CT scans; Praevalenz und klinische Bedeutung inzidenteller Herzbefunde im nicht EKG-getriggerten Thorax-CT

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    Quentin, M.; Kroepil, P.; Lanzman, R.S.; Blondin, D.; Miese, F.; Scherer, A. [Heinrich-Heine-Universitaet Duesseldorf, Institut fuer Radiologie, Duesseldorf (Germany); Steiner, S. [Klinikum der Heinrich-Heine-Universitaet Duesseldorf, Klinik fuer Kardiologie, Pneumologie und Angiologie, Duesseldorf (Germany); Choy, G.; Abbara, S. [Massachusetts General Hospital, Harvard Medical School, Cardiovascular Imaging Section, Boston (United States)

    2011-01-15

    The purpose of this study was to evaluate the prevalence and clinical significance of incidental cardiac findings in non-ECG-gated chest CT. Non-ECG-gated chest CT examinations of 300 patients were retrospectively analyzed for incidental cardiac findings. Subsequently, these findings were evaluated for their clinical relevance by a cardiologist. A total of 107 out of 300 examined patients had 174 incidental cardiac findings including coronary calcification (90), aortic/mitral valve calcification (42), iatrogenic changes (23), pericardial effusion (6), dilatation of the heart (4), myocardial changes (3), thrombus in the left ventricle (2), constrictive pericarditis (2) and atrial myxoma (1). Of the cardiac findings 51% were described in the written report and in 53 out of the 107 patients the cardiac findings were unknown. Newly detected incidental findings from 8 patients were rated as clinically significant: pericardial effusion (4), constrictive pericarditis (1), thrombus in the left ventricle (1), atrial myxoma (1) and dilatation of the heart (1). Incidental cardiac findings are frequent in non-ECG-gated chest CT and may have a high clinical relevance. (orig.) [German] Ziel dieser Studie war es, die Praevalenz und klinische Bedeutung inzidenteller Herzbefunde im nicht EKG-getriggerten Thorax-CT ohne primaer kardiale Fragestellung zu evaluieren. Dreihundert nicht EKG-getriggerte Thorax-CT-Untersuchungen wurden retrospektiv bzgl. inzidenteller Herzbefunde analysiert. Die klinische Bedeutung wurde von einem Kardiologen bewertet. Von 300 Patienten hatten 107 insgesamt 174 Herzbefunde: Koronarsklerose (90), Aorten-/Mitralklappenverkalkung (42), iatrogene Veraenderungen (23), Perikarderguss (6), Herzvergroesserung (4), Myokardpathologien (3), Perikardverkalkungen (2), Thrombus im linken Ventrikel (2) und Myxom (1). Im radiologischen Bericht wurden 51% aller Herzbefunde beschrieben. Bei 53 der 107 Patienten mit Herzbefund waren diese klinisch nicht bekannt. Als

  12. Prospectively ECG Gated CT pulmonary angiography versus helical ungated CT pulmonary angiography: Impact on cardiac related motion artifacts and patient radiation dose

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    Shuman, William P., E-mail: wshuman@u.washington.edu [Department of Radiology, 1959 NE Pacific Street, Box 357115, Seattle, WA 98195 (United States); Leipsic, Jonathon A., E-mail: JLeipsic@providencehealth.bc.ca [University of British Columbia and St. Paul' s Hospital, Department of Radiology, 1081 Burrard Street, Vancouver, BC, V6Z1Y6 (Canada); Busey, Janet M., E-mail: jbonny@u.washington.edu [Department of Radiology, 1959 NE Pacific Street, Box 357115, Seattle, WA 98195 (United States); Green, Douglas E., E-mail: dougreen@uw.edu [Department of Radiology, 1959 NE Pacific Street, Box 357115, Seattle, WA 98195 (United States); Pipavath, Sudhakar N., E-mail: snjp@u.wwashington.edu [Department of Radiology, 1959 NE Pacific Street, Box 357115, Seattle, WA 98195 (United States); Hague, Cameron J., E-mail: cjhague@interchange.ubc.ca [University of British Columbia and St. Paul' s Hospital, Department of Radiology, 1081 Burrard Street, Vancouver, BC, V6Z1Y6 (Canada); Koprowicz, Kent M., E-mail: kentk@u.washington.edu [Department of Radiology, 1959 NE Pacific Street, Box 357115, Seattle, WA 98195 (United States)

    2012-09-15

    Objective: To compare prospectively ECG gated CT pulmonary angiography (CTPA) with routine helical ungated CTPA for cardiac related motion artifacts and patient radiation dose. Subjects and methods: Twenty patients with signs and symptoms suspicious for pulmonary embolism and who had a heart rate below 85 were scanned with prospectively ECG gated CTPA. These gated exams were matched for several clinical parameters to exams from twenty similar clinical patients scanned with routine ungated helical CTPA. Three blinded independent reviewers subjectively evaluated all exams for overall pulmonary artery enhancement and for several cardiac motion related artifacts, including vessel blurring, intravascular shading, and double line. Reviewers also measured pulmonary artery intravascular density and image noise. Patient radiation dose for each technique was compared. Fourteen clinical prospectively ECG gated CTPA exams from a second institution were evaluated for the same parameters. Results: Prospectively ECG gated CTPA resulted in significantly decreased motion-related image artifact scores in lung segments adjacent to the heart compared to ungated CTPA. Measured image noise was not significantly different between the two types of CTPA exams. Effective dose was 28% less for prospectively ECG gated CTPA (4.9 mSv versus 6.8 mSv, p = 0.02). Similar results were found in the prospectively ECG gated exams from the second institution. Conclusion: Compared to routine helical ungated CTPA, prospectively ECG gated CTPA may result in less cardiac related motion artifact in lung segments adjacent to the heart and significantly less patient radiation dose.

  13. Diagnostic quality of time-averaged ECG-gated CT data

    NARCIS (Netherlands)

    Klein, A.; Oostveen, L.J.; Greuter, M.J.W.; Hoogeveen, Y.; Schultze Kool, L.J.; Slump, C.H.; Renema, W.K.J.; Samei, Ehsan; Hsieh, Jiang

    2009-01-01

    Purpose: ECG-gated CTA allows visualization of the aneurysm and stentgraft during the different phases of the cardiac cycle, although with a lower SNR per cardiac phase than without ECG gating using the same dose. In our institution, abdominal aortic aneurysm (AAA) is evaluated using non-ECG-gated C

  14. Optimization of Ecg Gating in Quantitative Femoral Angiography

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    Nilsson, S.; Berglund, I.; Erikson, U. [Univ. Hospital, Uppsala (Sweden). Dept. of Oncology, Radiology and Clinical Immunology; Johansson, J.; Walldius, G. [Karolinska Hospital, Stockholm (Sweden). King Gustav V Research Inst.

    2003-09-01

    Purpose: To determine which phase of the heart cycle would yield the highest reproducibility in measuring atherosclerosis-related variables such as arterial lumen volume and edge roughness. Material and Methods: 35 patients with hypercholesterolemia underwent select ive femoral angiography, repeated four times at 10-min intervals. The angiographies were performed with Ecg-gated exposures. In angiographies 1 and 2 the delay from R-wave maximum to each exposure was 0.1 s, in angiographies 3 and 4 the delay was 0.1, 0.3, 0.5 or 0.7 s or the exposures were performed 1/s without Ecg gating. Arterial lumen volume and edge roughness were measured in a 20-cm segment of the superficial femoral artery using a computer-based densitometric method. Measurement reproducibility was determined by comparing angiographies 1-2 and angiographies 3-4. Results: When measuring arterial lumen volume and edge roughness of a 20-cm segment of the femoral artery, reproducibility was not dependent on Ecg gating. In measuring single arterial diameters and cross-sectional areas, the reproducibility was better when exposures were made 0.1 s after the R-wave maximum than when using other settings of the Ecg gating device or without Ecg gating. Conclusion: The influence of pulsatile flow upon quantitative measurement in femoral angiograms seems to be the smallest possible in early systole, as can be demonstrated when measuring single diameters and cross-sectional areas. In variables based on integration over longer segments, measurement reproducibility seems to be independent of phase.

  15. AUTOMATED AGATSTON SCORE COMPUTATION IN A LARGE DATASET OF NON ECG-GATED CHEST COMPUTED TOMOGRAPHY.

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    González, Germán; Washko, George R; Estépar, Raúl San José

    2016-04-01

    The Agatston score, computed from ECG-gated computed tomography (CT), is a well established metric of coronary artery disease. It has been recently shown that the Agatston score computed from chest CT (non ECG-gated) studies is highly correlated with the Agatston score computed from cardiac CT scans. In this work we present an automated method to compute the Agatston score from chest CT images. Coronary arteries calcifications (CACs) are defined as voxels contained within the coronary arteries with a value greater or equal to 130 Hounsfield Units (HU). CACs are automatically detected in chest CT studies by locating the heart, generating a region of interest around it, thresholding the image in such region and applying a set of rules to discriminate CACs from calcifications in the main vessels or from metallic implants. We evaluate the methodology in a large cohort of 1500 patients for whom manual reference standard is available. Our results show that the Pearson correlation coefficient between manual and automated Agatston score is ρ = 0.86 (p < 0.0001).

  16. Retrospectively ECG-gated multi-detector row CT of the chest: does ECG-gating improve three-dimensional visualization of the bronchial tree?

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    Schertler, T.; Wildermuth, S.; Willmann, J.K.; Crook, D.W.; Marincek, B.; Boehm, T. [Dept. Medical Radiology, Inst. of Diagnostic Radiology, Univ. Hospital Zurich (Switzerland)

    2004-04-01

    Purpose: To determine the impact of retrospectively ECG-gated multi-detector row CT (MDCT) on three-dimensional (3D) visualization of the bronchial tree and virtual bronchoscopy (VB) as compared to non-ECG-gated data acquisition. Materials and Methods: Contrast-enhanced retrospectively ECG-gated and non-ECG-gated MDCT of the chest was performed in 25 consecutive patients referred for assessment of coronary artery bypass grafts and pathology of the ascending aorta. ECG-gated MDCT data were reconstructed in diastole using an absolute reverse delay of -400 msec in all patients. In 10 patients additional reconstructions at -200 msec, -300 msec, and -500 msec prior to the R-wave were performed. Shaded surface display (SSD) and virtual bronchoscopy (VB) for visualization of the bronchial segments was performed with ECG-gated and non-ECG-gated MDCT data. The visualization of the bronchial tree underwent blinded scoring. Effective radiation dose and signal-to-noise ratio (SNR) for both techniques were compared. Results: There was no significant difference in visualizing single bronchial segments using ECG-gated compared to non-ECG-gated MDCT data. However, the total sum of scores for all bronchial segments visualized with non-ECG-gated MDCT was significantly higher compared to ECG-gated MDCT (P<0.05). The summary scores for visualization of bronchial segments for different diastolic reconstructions did not differ significantly. The effective radiation dose and the SNR were significantly higher with the ECG-gated acquisition technique (P<0.05). Conclusion: The bronchial tree is significantly better visualized when using non-ECG-gated MDCT compared to ECG-gated MDCT. Additionally, non-ECG-gated techniques require less radiation exposure. Thus, the current retrospective ECG-gating technique does not provide any additional benefit for 3D visualization of the bronchial tree and VB. (orig.) [German] Ziel: Untersuchung des Einflusses der retrospektiven EKG-Synchronisierung auf

  17. Detectability of motions in AAA with ECG-gated CTA: A quantitative study

    NARCIS (Netherlands)

    Klein, Almar; Oostveen, Luuk J.; Greuter, Marcel J.W.; Hoogeveen, Yvonne; Schultze Kool, Leo J.; Slump, Cornelis H.; Renema, W. Klaas Jan

    2009-01-01

    Purpose: ECG-gated CT enables the visualization of motions caused by the beating of the heart. Although ECG gating is frequently used in cardiac CT imaging, this technique is also very promising for evaluating vessel wall motion of the aortic artery and the motions of (stent grafts inside) abdominal

  18. Detectability of motions in AAA with ECG-gated CTA: a quantitative study.

    NARCIS (Netherlands)

    Klein, A.; Oostveen, L.J.; Greuter, M.J.; Hoogeveen, Y.L.; Kool, L.J.; Slump, C.H.; Renema, W.K.J.

    2009-01-01

    PURPOSE: ECG-gated CT enables the visualization of motions caused by the beating of the heart. Although ECG gating is frequently used in cardiac CT imaging, this technique is also very promising for evaluating vessel wall motion of the aortic artery and the motions of (stent grafts inside) abdominal

  19. Detectability of motions in AAA with ECG-gated CTA : A quantitative study

    NARCIS (Netherlands)

    Klein, Almar; Oostveen, Luuk J.; Greuter, Marcel J. W.; Hoogeveen, Yvonne; Kool, Leo J. Schultze; Slump, Cornelis H.; Renema, W. Klaas Jan

    2009-01-01

    Purpose: ECG-gated CT enables the visualization of motions caused by the beating of the heart. Although ECG gating is frequently used in cardiac CT imaging, this technique is also very promising for evaluating vessel wall motion of the aortic artery and the motions of (stent grafts inside) abdominal

  20. 128-slice CT angiography of the aorta without ECG-gating: efficacy of faster gantry rotation time and iterative reconstruction in terms of image quality and radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Russo, Vincenzo; Garattoni, Monica; Buia, Francesco; Attina, Domenico; Lovato, Luigi; Zompatori, Maurizio [University Hospital ' ' S.Orsola' ' , Cardio-Thoracic-Vascular Department, Cardio-Thoracic Radiology Unit, Bologna (Italy)

    2016-02-15

    To evaluate image quality and radiation dose of non ECG-gated 128-slice CT angiography of the aorta (CTAA) with fast gantry rotation time and iterative reconstruction. Four hundred and eighty patients underwent non ECG-gated CTAA. Qualitative and quantitative image quality assessments were performed. Radiation dose was assessed and compared with the dose of patients who underwent ECG-gated CTAA (n = 126) and the dose of previous CTAA performed with another CT (n = 339). Image quality (aortic root-ascending portion) was average-to-excellent in more than 94 % of cases, without any non-diagnostic scan. For proximal coronaries, image quality was average-to-excellent in more than 50 %, with only 21.5 % of non-diagnostic cases. Quantitative analysis results were also good. Mean radiation dose for thoracic CTAA was 5.6 mSv versus 20.6 mSv of ECG-gated protocol and 20.6 mSv of 16-slice CTAA scans, with an average dose reduction of 72.8 % (p < 0.001). Mean radiation dose for thoracic-abdominal CTAA was 9.7 mSv, versus 20.9 mSv of 16-slice CTAA scans, with an average dose reduction of 53.6 % (p < 0.001). Non ECG-gated 128-slice CTAA is feasible and able to provide high quality visualization of the entire aorta without significant motion artefacts, together with a considerable dose and contrast media volume reduction. (orig.)

  1. Feasibility of epicardial adipose tissue quantification in non-ECG-gated low-radiation-dose CT: comparison with prospectively ECG-gated cardiac CT

    Energy Technology Data Exchange (ETDEWEB)

    Simon-Yarza, Isabel; Viteri-Ramirez, Guillermo; Saiz-Mendiguren, Ramon; Slon-Roblero, Pedro J.; Paramo, Maria [Dept. of Radiology, Clinica Univ. de Navarra, Pamplona (Spain); Bastarrika, Gorka [Dept. of Radiology, Clinica Univ. de Navarra, Pamplona (Spain); Cardiac Imaging Unit, Clinica Univ. de Navarra, Pamplona (Spain)], e-mail: bastarrika@unav.es

    2012-06-15

    Background: Epicardial adipose tissue (EAT) is an important indicator of cardiovascular risk. This parameter is generally assessed on ECG-gated computed tomography (CT) images. Purpose: To evaluate feasibility and reliability of EAT quantification on non-gated thoracic low-radiation-dose CT examinations with respect to prospectively ECG-gated cardiac CT acquisition. Material and Methods: Sixty consecutive asymptomatic smokers (47 men; mean age 64 {+-} 9.8 years) underwent low-dose CT of the chest and prospectively ECG-gated cardiac CT acquisitions (64-slice dual-source CT). The two examinations were reconstructed with the same range, field of view, slice thickness, and convolution algorithm. Two independent observers blindly quantified EAT volume using commercially available software. Data were compared with paired sample Student t-test, concordance correlation coefficients (CCC), and Bland-Altman plots. Results: No statistically significant difference was observed for EAT volume quantification with low-dose-CT (141.7 {+-} 58.3 mL) with respect to ECG-gated CT (142.7 {+-} 57.9 mL). Estimation of CCC showed almost perfect concordance between the two techniques for EAT-volume assessment (CCC, 0.99; mean difference, 0.98 {+-} 5.1 mL). Inter-observer agreement for EAT volume estimation was CCC: 0.96 for low-dose-CT examinations and 0.95 for ECG-gated CT. Conclusion: Non-gated low-dose CT allows quantifying EAT with almost the same concordance and reliability as using dedicated prospectively ECG-gated cardiac CT acquisition protocols.

  2. Quantification of Intracranial Aneurysm Morphodynamics from ECG-gated CT Angiography

    NARCIS (Netherlands)

    Firouzian, A.; Manniesing, R.; Metz, C.T.; Risselada, R.; Klein, S.; Kooten, F. van; Sturkenboom, M.C.; Lugt, A. van der; Niessen, W.J.

    2013-01-01

    Rationale and Objectives: Aneurysm morphodynamics is potentially relevant for assessing aneurysm rupture risk. A method is proposed for automated quantification and visualization of intracranial aneurysm morphodynamics from ECG-gated computed tomography angiography (CTA) data. Materials and Methods:

  3. Low dose prospective ECG-gated delayed enhanced dual-source computed tomography in reperfused acute myocardial infarction comparison with cardiac magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Wang Rui, E-mail: rui_wang1979@yahoo.cn [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Zhang Zhaoqi, E-mail: zhaoqi5000@vip.sohu.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Xu Lei, E-mail: leixu2001@hotmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Ma Qin, E-mail: tel1367@gmail.com [Department of Emergency, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); He Yi, E-mail: heyi139@sina.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Lu Dongxu, E-mail: larry.hi@163.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Yu Wei, E-mail: yuwei02@gmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Fan Zhanming, E-mail: fanzm120@tom.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China)

    2011-11-15

    Purpose: To determine whether prospective electrocardiogram (ECG)-gated delayed contrast-enhanced dual-source computed tomography (DCE-DSCT) can accurately delineate the extension of myocardial infarction (MI) compared with delayed enhanced cardiac MR (DE-MR). Material and methods: Eleven patients were examined using dual-source CT and cardiac MR in 2 weeks after a first reperfused MI. DCE-DSCT scan protocol was performed with prospective ECG-gating sequential scan model 7 min after contrast administration. In a 17-model, infarcted myocardium detected by DE-MR was categorized as transmural and subendocardial extension. Segment of infarcted location and graded transmurality were compared between DCE-MDCT and DE-MR. Results: In all eleven patients, diagnostic quality was obtained for depicting delayed enhanced myocardium. Agreement between DCE-DSCT and MR was good on myocardial segment based comparison (kappa = 0.85, p < 0.001), and on transmural and subendocardial infarction type comparison (kappa = 0.82, p < 0.001, kappa = 0.52, p < 0.001, respectively). CT value was higher on infarcted region than that of normal region (100.02 {+-} 9.57 HU vs. 72.63 {+-} 7.32 HU, p < 0.001). Radiation dose of prospectively ECG-gating protocol were 0.99 {+-} 0.08 mSv (0.82-1.19 mSv). Conclusions: Prospective ECG-gated DCE-DSCT can accurately assess the extension and the patterns of myocardial infarction with low radiation dose.

  4. ECG-gated computed tomography: a new role for patients with suspected aortic prosthetic valve endocarditis

    Energy Technology Data Exchange (ETDEWEB)

    Fagman, Erika; Flinck, Agneta; Lamm, Carl [Sahlgrenska University Hospital, Department of Radiology, Gothenburg (Sweden); Perrotta, Sossio [Sahlgrenska University Hospital, Department of Cardiovascular Surgery and Anaesthesia, Gothenburg (Sweden); Bech-Hanssen, Odd [Sahlgrenska University Hospital, Department of Clinical Physiology, Gothenburg (Sweden); Sahlgrenska University Hospital, Department of Cardiology, Gothenburg (Sweden); Olaison, Lars [Sahlgrenska University Hospital, Department of Infectious Diseases, Gothenburg (Sweden); Svensson, Gunnar [Sahlgrenska University Hospital, Department of Cardiovascular Surgery and Anaesthesia, Gothenburg (Sweden); The Sahlgrenska Academy at the University of Gothenburg, Department of Molecular and Clinical Medicine, Institute of Medicine, Gothenburg (Sweden)

    2012-11-15

    The aim of this prospective study was to investigate the agreement in findings between ECG-gated CT and transoesophageal echocardiography (TEE) in patients with aortic prosthetic valve endocarditis (PVE). Twenty-seven consecutive patients with PVE underwent 64-slice ECG-gated CT and TEE and the results were compared. Imaging was compared with surgical findings (surgery was performed in 16 patients). TEE suggested the presence of PVE in all patients [thickened aortic wall (n = 17), vegetation (n = 13), abscess (n = 16), valvular dehiscence (n = 10)]. ECG-gated CT was positive in 25 patients (93 %) [thickened aortic wall (n = 19), vegetation (n = 7), abscess (n = 18), valvular dehiscence (n = 7)]. The strength of agreement [kappa (95 % CI)] between ECG-gated CT and TEE was very good for thickened wall [0.83 (0.62-1.0)], good for abscess [0.68 (0.40-0.97)] and dehiscence [0.75 (0.48-1.0)], and moderate for vegetation [0.55 (0.26-0.88)]. The agreement was good between surgical findings (abscess, vegetation and dehiscence) and imaging for ECG-gated CT [0.66 (0.49-0.87)] and TEE [0.79 (0.62-0.96)] and very good for the combination of ECG-gated CT and TEE [0.88 (0.74-1.0)]. Our results indicate that ECG-gated CT has comparable diagnostic performance to TEE and may be a valuable complement in the preoperative evaluation of patients with aortic PVE. (orig.)

  5. Integrated cardio-thoracic imaging with ECG-Gated 64-slice multidetector-row CT: initial findings in 133 patients

    Energy Technology Data Exchange (ETDEWEB)

    Salem, Randa; Remy-Jardin, Martine; Delhaye, Damien; Khalil, Chadi; Teisseire, Antoine; Remy, Jacques [Hospital Calmette, University Center of Lille, Department of Thoracic Imaging, LILLE cedex (France); Delannoy-Deken, Valerie; Duhamel, Alain [University of Lille, Place de Verdun, Department of Medical Statistics, LILLE cedex (France)

    2006-09-15

    The purpose of this study was to investigate the possibility of assessing the underlying respiratory disease as well as cardiac function during ECG-gated CT angiography of the chest with 64-slice multidetector-row CT (MDCT). One hundred thirty-three consecutive patients in sinus rhythm with known or suspected ventricular dysfunction underwent an ECG-gated CT angiographic examination of the chest without {beta}-blockers using the following parameters: (1) collimation: 32 x 0.6 mm with z-flying focal spot for the acquisition of 64 overlapping 0.6-mm slices (Sensation 64; Siemens); rotation time: 0.33 s; pitch: 0.3; 120 kV; 200 mAs; ECG-controlled dose modulation (ECG-pulsing) and (2) 120 ml of a 35% contrast agent. Data were reconstructed: (1) to evaluate the underlying respiratory disease (1-mm thick lung and mediastinal scans reconstructed at 55% of the R-R interval; i.e., ''morphologic scans'') and (2) to determine right (RVEF) and left (LVEF) ventricular ejection fractions (short-axis systolic and diastolic images; Argus software; i.e., ''functional scans''). The mean heart rate was 73 bpm (range: 42-120) and the mean scan time was 18.11{+-}2.67 s (range: 10-27). A total of 123 examinations (92%) had both lung and mediastinal images rated as diagnostic scans, whereas 10 examinations (8%) had non-diagnostic images altered by the presence of respiratory-motion artifacts (n=4) or cyclic artifacts related to the use of a pitch value of 0.3 in patients with a very low heart rate during data acquisition (n=6). Assessment of right and left ventricular function was achievable in 124 patients (93%, 95% CI: 88-97%). For these 124 examinations, the mean RVEF was 46.10% ({+-}9.5; range: 20-72) and the mean LVEF was 58.23% ({+-}10.88; range: 20-83). In the remaining nine patients, an imprecise segmentation of the right and left ventricular cavities was considered as a limiting factor for precise calculation of end-systolic and end

  6. Reproducibility of aortic pulsatility measurements from ECG-gated abdominal CTA in patients with abdominal aortic aneurysms

    Science.gov (United States)

    Manduca, Armando; Fletcher, Joel G.; Wentz, Robert J.; Shields, Raymond C.; Vrtiska, Terri J.; Siddiki, Hassan; Nielson, Theresa

    2009-02-01

    Purpose: ECG-gated abdominal CT angiography with reconstruction of multiple, temporally overlapping CT angiography datasets has been proposed for measuring aortic pulsatility. The purpose of this work is to develop algorithms to segment the aorta from surrounding structures from CTA datasets across cardiac phases, calculate registered centerlines and measurements of regional aortic pulsatility in patients with AAA, and to assess the reproducibility of these measurements. Methods: ECG-gated CTA was performed with a temporal resolution of 165 ms, reconstructed to 1 mm slices ranging at 14 cardiac phase points. Data sets were obtained from 17 patients on which two such scans were performed 6 to 12 months apart. Automated segmentation, centerline generation, and registration of centerlines between phases was performed, followed by calculation of cross-sectional areas and regional and local pulsatility. Results: Pulsatility calculations for the supraceliac region were very reproducible between earlier and later scans of the same patient, with average differences less than 1% for pulsatility values ranging from 2% to 13%. Local radial pulsatilities were also reproducible to within ~1%. Aneurysm volume changes between scans can also be quantified. Conclusion: Automated segmentation, centerline generation, and registration of temporally resolved CTA datasets permit measurements of regional changes in cross-sectional area over the course of the cardiac cycle (i.e., regional aortic pulsatility). These measurements are reproducible between scans 6-12 months apart, with differences in aortic areas reflecting both aneurysm remodeling and changes in blood pressure. Regional pulsatilities ranged from 2 to 13% but were reproducible at the 1% level.

  7. Non-ECG-gated myocardial perfusion MRI using continuous magnetization-driven radial sampling.

    Science.gov (United States)

    Sharif, Behzad; Dharmakumar, Rohan; Arsanjani, Reza; Thomson, Louise; Bairey Merz, C Noel; Berman, Daniel S; Li, Debiao

    2014-12-01

    Establishing a high-resolution non-ECG-gated first-pass perfusion (FPP) cardiac MRI technique may improve accessibility and diagnostic capability of FPP imaging. We propose a non-ECG-gated FPP imaging technique using continuous magnetization-driven golden-angle radial acquisition. The main purpose of this preliminary study is to evaluate whether, in the simple case of single-slice two-dimensional imaging, adequate myocardial contrast can be obtained for accurate visualization of hypoperfused territories in the setting of myocardial ischemia. A T1-weighted pulse sequence with continuous golden-angle radial sampling was developed for non-ECG-gated FPP imaging. A sliding-window scheme with no temporal acceleration was used to reconstruct 8 frames/s. Canines were imaged at 3T with and without coronary stenosis using the proposed scheme and a conventional magnetization-prepared ECG-gated FPP method. Our studies showed that the proposed non-ECG-gated method is capable of generating high-resolution (1.7 × 1.7 × 6 mm(3) ) artifact-free FPP images of a single slice at high heart rates (92 ± 21 beats/min), while matching the performance of conventional FPP imaging in terms of hypoperfused-to-normal myocardial contrast-to-noise ratio (proposed: 5.18 ± 0.70, conventional: 4.88 ± 0.43). Furthermore, the detected perfusion defect areas were consistent with the conventional FPP images. Non-ECG-gated FPP imaging using optimized continuous golden-angle radial acquisition achieves desirable image quality (i.e., adequate myocardial contrast, high spatial resolution, and minimal artifacts) in the setting of ischemia. © 2014 Wiley Periodicals, Inc.

  8. Non-ECG-gated CT pulmonary angiography and the prediction of right ventricular dysfunction in patients suspected of pulmonary embolism

    DEFF Research Database (Denmark)

    Gutte, Henrik; Mortensen, Jann; Mørk, Mette Louise;

    2016-01-01

    PURPOSE: Right ventricular dysfunction (RVD) is an important prognostic factor of 30-day mortality in patients with acute pulmonary embolism (PE). The aim of our study was to evaluate whether non-electrocardiogram (ECG)-gated cardiovascular parameters attained during computed tomography pulmonary...... angiography (CTPA) could predict RVD in patients suspected of PE using ECG-gated cardiac CT angiography as reference. METHODS: Consecutive patients suspected of PE were referred to a ventilation/perfusion single-photon emission tomography (V/Q-SPECT) as first-line imaging procedure. Patients had a V....../Q-SPECT/CT, a CTPA and an ECG-gated cardiac CT angiography performed the same day. RESULTS: A total of 71 patients were available for analysis. Seventeen patients (24%) had RVD. The non-ECG-gated dimensions of left and right ventricle and the major vessels were correlated with ECG-gated cardiac dimensions. The size...

  9. Achieving consistent image quality with dose optimization in 64-row multidetector computed tomography prospective ECG gated coronary calcium scoring.

    Science.gov (United States)

    Pan, Zilai; Pang, Lifang; Li, Jianying; Zhang, Huan; Yang, Wenjie; Ding, Bei; Chai, Weimin; Chen, Kemin; Yao, Weiwu

    2011-04-01

    To evaluate the clinical value of a body mass index (BMI) based tube current (mA) selection method for obtaining consistent image quality with dose optimization in MDCT prospective ECG gated coronary calcium scoring. A formula for selecting mA to achieve desired image quality based on patient BMI was established using a control group (A) of 200 MDCT cardiac patients with a standard scan protocol. One hundred patients in Group B were scanned with this BMI-dependent mA for achieving a desired noise level of 18 HU at 2.5 mm slice thickness. The CTDIvol and image noise on the ascending aorta for the two groups were recorded. Two experienced radiologists quantitatively evaluated the image quality using scores of 1-4 with 4 being the highest. The image quality scores had no statistical difference (P = 0.71) at 3.89 ± 0.32, 3.87 ± 0.34, respectively, for groups A and B of similar BMI. The image noise in Group A had linear relationship with BMI. The image noise in Group B using BMI-dependent mA was independent of BMI with average value of 17.9 HU and smaller deviations for the noise values than in Group A (2.0 vs. 2.9 HU). There was a 35% dose reduction with BMI-dependent mA selection method on average with the lowest effective dose being only 0.35 mSv for patient with BMI of 18.3. A quantitative BMI-based mA selection method in MDCT prospective ECG gated coronary calcium scoring has been proposed to obtain a desired and consistent image quality and provide dose optimization across patient population.

  10. An integrated bioimpedance—ECG gating technique for respiratory and cardiac motion compensation in cardiac PET

    Science.gov (United States)

    Koivumäki, Tuomas; Nekolla, Stephan G.; Fürst, Sebastian; Loher, Simone; Vauhkonen, Marko; Schwaiger, Markus; Hakulinen, Mikko A.

    2014-10-01

    Respiratory motion may degrade image quality in cardiac PET imaging. Since cardiac PET studies often involve cardiac gating by ECG, a separate respiratory monitoring system is required increasing the logistic complexity of the examination, in case respiratory gating is also needed. Thus, we investigated the simultaneous acquisition of both respiratory and cardiac gating signals using II limb lead mimicking electrode configuration during cardiac PET scans of 11 patients. In addition to conventional static and ECG-gated images, bioimpedance technique was utilized to generate respiratory- and dual-gated images. The ability of the bioimpedance technique to monitor intrathoracic respiratory motion was assessed estimating cardiac displacement between end-inspiration and -expiration. The relevance of dual gating was evaluated in left ventricular volume and myocardial wall thickness measurements. An average 7.6  ±  3.3 mm respiratory motion was observed in the study population. Dual gating showed a small but significant increase (4 ml, p = 0.042) in left ventricular myocardial volume compared to plain cardiac gating. In addition, a thinner myocardial wall was observed in dual-gated images (9.3  ±  1.3 mm) compared to cardiac-gated images (11.3  ±  1.3 mm, p = 0.003). This study shows the feasibility of bioimpedance measurements for dual gating in a clinical setting. The method enables simultaneous acquisition of respiratory and cardiac gating signals using a single device with standard ECG electrodes.

  11. Noninvasive assessment of coronary artery disease by multislice spiral computed tomography using a new retrospectively ECG-gated image reconstruction technique. Comparison with angiographic results

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Yuichi; Matsumoto, Naoya; Kato, Masahiko [Nihon Univ., Tokyo (Japan). Surugadai Hospital] [and others

    2003-04-01

    The present study was designed to investigate the accuracy of multislice spiral computed tomography (MSCT) in detecting coronary artery disease, compared with coronary angiography (CAG), using a new retrospectively ECG-gated reconstruction method that reduced cardiac motion artifact. The study group comprised 54 consecutive patients undergoing MSCT and CAG. MSCT was performed using a SOMATOM Volume Zoom (4-detector-row, Siemens, Germany) with slice thickness 1.0 mm, pitch 1.5 (table feed: 1.5 mm per rotation) and gantry rotation time 500 ms. Metoprolol (20-60 mg) was administered orally prior to MSCT imaging. ECG-gated image reconstruction was performed with the reconstruction window (250 ms) positioned immediately before atrial contraction in order to reduce the cardiac motion artifact caused by the abrupt diastolic ventricular movement occurring during the rapid filling and atrial contraction periods. Following inspection of the volume rendering images, multiplanar reconstruction images and axial images of the left main coronary artery (LMCA), left anterior descending artery (LAD), left circumflex artery (LCx) and right coronary artery (RCA) were obtained and evaluated for luminal narrowing. The results were compared with those obtained by CAG. Of 216 coronary arteries, 206 (95.4%) were assessable; 10 arteries were excluded from the analysis because of severe calcification (n=4), stents (n=3) or insufficient contrast enhancement (n=3). The sensitivity to detect coronary stenoses {>=}50% was 93.5% and the specificity to define luminal narrowing <50% was 97.2%. The positive predictive value and the negative predictive value were 93.5% and 97.2%, respectively. The sensitivity was still satisfactory (80.6%) even when non-assessable arteries were included in the analysis. The new retrospectively ECG-gated reconstruction method for MSCT has excellent diagnostic accuracy in detecting significant coronary artery stenoses. (author)

  12. Diagnostic accuracy of prospective ECG gated coronary computed tomography on a 256 slices scanner: Daily practice experience

    Directory of Open Access Journals (Sweden)

    Ahmed M. Fareed

    2014-03-01

    Conclusions: In a highly prevalence diseased population, prospective ECG-gated CTCA using 256-slice scanner is highly accurate for detection and quantification of the degree of coronary luminal stenosis in comparison to ICA.

  13. Prospective ECG-gated 320-row CT angiography of the whole aorta and coronary arteries

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yu.; Fan, Zhanming; Xu, Lei; Yang, Lin; Xin, Haiyan; Zhang, Nan [Capital Medical University, Department of Radiology, Beijing An Zhen Hospital, Beijing (China); Capital Medical University, Ministry of Education, The Key Laboratory of Remodeling-Related Cardiovascular Diseases, Beijing An Zhen Hospital, Beijing (China); Zhang, Zhaoqi [Capital Medical University, Department of Radiology, Beijing An Zhen Hospital, Beijing (China)

    2012-11-15

    To investigate the feasibility of using a prospective ECG-gated wide-volume protocol in CT angiography (CTA) of the whole aorta and coronary arteries (CA). A total of 61 consecutive patients with suspected acute aortic diseases underwent CTA of the whole aorta using a prospective ECG-gated wide-volume CT protocol without heart rate (HR) control. The exposure window was set at 40-50 % of R-R interval (HR {>=}70 bpm) or 70-80 % of R-R interval (HR <70 bpm) in a single heartbeat. The image quality of the ascending aorta, aortic valve and CA was evaluated for motion artefacts. The mean attenuation was measured at different levels of the aorta. The radiation dose and contrast medium volume were recorded. All of the examinations were performed successfully. The image quality was acceptable in the ascending aorta, aortic valve (100 %) and CA (94.4 %). The mean radiation dose was 18.42 {+-} 5.02 mSv. Of 61 patients, 14 were diagnosed with aortic aneurysm and 35 were diagnosed with aortic dissection or intramural haematoma. Coronary artery stenosis was detected in 12 patients. For patients with aortic diseases, CTA of the whole aorta using a prospective ECG-gated wide-volume protocol has the potential to provide additional information about the CA and aortic valve with lower radiation exposure. (orig.)

  14. Residual motion compensation in ECG-gated interventional cardiac vasculature reconstruction

    Science.gov (United States)

    Schwemmer, C.; Rohkohl, C.; Lauritsch, G.; Müller, K.; Hornegger, J.

    2013-06-01

    Three-dimensional reconstruction of cardiac vasculature from angiographic C-arm CT (rotational angiography) data is a major challenge. Motion artefacts corrupt image quality, reducing usability for diagnosis and guidance. Many state-of-the-art approaches depend on retrospective ECG-gating of projection data for image reconstruction. A trade-off has to be made regarding the size of the ECG-gating window. A large temporal window is desirable to avoid undersampling. However, residual motion will occur in a large window, causing motion artefacts. We present an algorithm to correct for residual motion. Our approach is based on a deformable 2D-2D registration between the forward projection of an initial, ECG-gated reconstruction, and the original projection data. The approach is fully automatic and does not require any complex segmentation of vasculature, or landmarks. The estimated motion is compensated for during the backprojection step of a subsequent reconstruction. We evaluated the method using the publicly available CAVAREV platform and on six human clinical datasets. We found a better visibility of structure, reduced motion artefacts, and increased sharpness of the vessels in the compensated reconstructions compared to the initial reconstructions. At the time of writing, our algorithm outperforms the leading result of the CAVAREV ranking list. For the clinical datasets, we found an average reduction of motion artefacts by 13 ± 6%. Vessel sharpness was improved by 25 ± 12% on average.

  15. Axial scanning in confocal microscopy employing adaptive lenses (CAL).

    Science.gov (United States)

    Koukourakis, Nektarios; Finkeldey, Markus; Stürmer, Moritz; Leithold, Christoph; Gerhardt, Nils C; Hofmann, Martin R; Wallrabe, Ulrike; Czarske, Jürgen W; Fischer, Andreas

    2014-03-10

    In this paper we analyze the capability of adaptive lenses to replace mechanical axial scanning in confocal microscopy. The adaptive approach promises to achieve high scan rates in a rather simple implementation. This may open up new applications in biomedical imaging or surface analysis in micro- and nanoelectronics, where currently the axial scan rates and the flexibility at the scan process are the limiting factors. The results show that fast and adaptive axial scanning is possible using electrically tunable lenses but the performance degrades during the scan. This is due to defocus and spherical aberrations introduced to the system by tuning of the adaptive lens. These detune the observation plane away from the best focus which strongly deteriorates the axial resolution by a factor of ~2.4. Introducing balancing aberrations allows addressing these influences. The presented approach is based on the employment of a second adaptive lens, located in the detection path. It enables shifting the observation plane back to the best focus position and thus creating axial scans with homogeneous axial resolution. We present simulated and experimental proof-of-principle results.

  16. Acute chest pain in emergency room. Preliminary findings with 40-64-slice CT ECG-gated of the whole chest.

    Science.gov (United States)

    Coche, E

    2007-01-01

    ECG-gated MDCT of the entire chest represents the latest technical advance in the diagnostic work-up of atypical chest pain. The authors report their preliminary experience with the use of 40 and 64-slice CT in the emergency room and recommend to study only patients with moderate likelihood of coronary artery disease. ECG-gated MDCT of the entire chest will be preferentially performed on 64-slice MDCT rather than 40-slice MDCT because it enable to reduce the scan time (18 seconds versus 28 seconds acquisition time), the volume of contrast medium (82 mL + 15 mL versus 97 mL + 15 mL of highly concentrated contrast agent for a patient of 70 kgs) and radiation exposure (17 mSv versus 19 mSv). Approximately 1500 to 2000 of images are produced and need to be analysed on a dedicated workstation by a radiologist expert in cardiac and thoracic disorders. At the present time, only a few studies exist in the literature showing some promising results but further large clinical studies are needed before to implement such sophisticated protocol in emergency room.

  17. Comprehensive cardiovascular ECG-gated MDCT as a standard diagnostic tool in patients with acute chest pain

    Energy Technology Data Exchange (ETDEWEB)

    Runza, G. [Department of Radiology, University of Palermo (Italy)], E-mail: grunza@sirm.org; La Grutta, L.; Alaimo, V. [Department of Radiology, University of Palermo (Italy); Evola, S. [Department of Cardiology, University of Palermo (Italy); Lo Re, F.; Bartolotta, T.V. [Department of Radiology, University of Palermo (Italy); Cademartiri, F. [Department of Radiology and Cardiology, Erasmus Medical Center, Rotterdam (Netherlands); Department of Radiology and Cardiology, Cardiovascular CT Unit, University Hospital, Parma (Italy); Midiri, M. [Department of Radiology, University of Palermo (Italy)

    2007-10-15

    Acute myocardial infarction, pulmonary embolism, and aortic dissection are diseases associated with acute chest pain and may lead to severe morbidity and mortality. These diseases may not be trivial to diagnose in the settings of emergency room. ECG-gated multi-detector computed tomography (MDCT), already established for the assessment of pulmonary embolism and aortic dissection, provides reliable information regarding the triage of patients with acute coronary syndrome in the emergency room. MDCT recently appeared to be logistically feasible and a promising comprehensive method for the evaluation of cardiac and non-cardiac chest pain in emergency department patients. The possibility to scan the entire thorax visualizing the thoracic aorta, the pulmonary arteries, and the coronary arteries could provide a new approach to the triage of acute chest pain. The inherent advantage of MDCT with cardiac state-of-the-art capabilities is the rapid investigation of the main sources of acute chest pain with a high negative predictive value. Recent studies also reports an advantage in terms of costs. With current evidence, the selection of patients with acute chest pain candidates to MDCT should remain restricted to avoid unjustified risk of ionizing radiation.

  18. Dual-source computed tomography: Estimation of radiation exposure of ECG-gated and ECG-triggered coronary angiography

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    Ketelsen, Dominik [Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tuebingen (Germany)], E-mail: dominik.ketelsen@med.uni-tuebingen.de; Thomas, Christoph; Werner, Matthias; Luetkhoff, Marie H. [Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tuebingen (Germany); Buchgeister, Markus [Departments of Radiotherapy and Radiooncology, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tuebingen (Germany); Tsiflikas, Ilias; Reimann, Anja [Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tuebingen (Germany); Burgstahler, Christof [Department of Cardiology, University Hospital Tuebingen, Ottfried-Mueller-Strasse 10, 72076 Tuebingen (Germany); Brodoefel, Harald; Kopp, Andreas F.; Claussen, Claus D.; Heuschmid, Martin [Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tuebingen (Germany)

    2010-02-15

    Purpose: The aim of the study was to estimate radiation exposure of coronary calcium scoring and angiography using ECG-gated and ECG-triggered dual-source computed tomography. Materials and methods: An Alderson Rando phantom equipped with thermoluminescent dosimeters was used for all dose measurements. Effective dose was calculated according to ICRP 103. Radiation exposure was performed on a dual-source computed tomography (DSCT) scanner with standard protocols for calcium scoring (DSCT-Ca) and coronary angiography (DSCTA) at different heart rates (40-100 beats/min). Furthermore, a scanning protocol with ECG-triggering as well as a standard chest CT scan were evaluated. Results: Depending on gender, heart rate and ECG-pulsing, the effective dose of a complete cardiac DSCT (DSCT-Ca and DSCTA) scan varies from 10.2 to 32.6 mSv. The effective radiation dose increased significantly with lower heart rates (p < 0.035). ECG-pulsing reduced the radiation exposure significantly in DSCTA (p < 0.001). Due to breast tissue in the primary scan range, females' doses showed an increase up to 69.9% compared to males in scan protocols without ECG-pulsing. Prospective ECG-triggered DSCTA resulted in estimated effective doses from 2.8 mSv (males) to 4.1 mSv (females). Conclusion: The ECG-pulsing technique has proven its effectiveness to reduce effective dose in coronary CT angiography and is recommended for all patients with regular heart rates. The patient's heart rate influences the radiation exposure with a significant decrease at higher heart rates. Due to its lower dose, ECG-triggered DSCTA should be implemented for special indications, i.e. for diagnosis of pathologies of the aortic root and the ascending aorta.

  19. Imaging the pericardium: appearances on ECG-gated 64-detector row cardiac computed tomography

    Science.gov (United States)

    O'Leary, S M; Williams, P L; Williams, M P; Edwards, A J; Roobottom, C A; Morgan-Hughes, G J; Manghat, N E

    2010-01-01

    Multidetector row computed tomography (MDCT) with its high spatial and temporal resolution has now become an established and complementary method for cardiac imaging. It can now be used reliably to exclude significant coronary artery disease and delineate complex coronary artery anomalies, and has become a valuable problem-solving tool. Our experience with MDCT imaging suggests that it is clinically useful for imaging the pericardium. It is important to be aware of the normal anatomy of the pericardium and not mistake normal variations for pathology. The pericardial recesses are visible in up to 44% of non-electrocardiogram (ECG)-gated MDCT images. Abnormalities of the pericardium can now be identified with increasing certainty on 64-detector row CT; they may be the key to diagnosis and therefore must not be overlooked. This educational review of the pericardium will cover different imaging techniques, with a significant emphasis on MDCT. We have a large research and clinical experience of ECG-gated cardiac CT and will demonstrate examples of pericardial recesses, their variations and a wide variety of pericardial abnormalities and systemic conditions affecting the pericardium. We give a brief relevant background of the conditions and reinforce the key imaging features. We aim to provide a pictorial demonstration of the wide variety of abnormalities of the pericardium and the pitfalls in the diagnosis of pericardial disease. PMID:20197434

  20. Prospective and retrospective ECG-gating for CT coronary angiography perform similarly accurate at low heart rates

    Energy Technology Data Exchange (ETDEWEB)

    Stolzmann, Paul, E-mail: paul.stolzmann@usz.ch [Institute of Diagnostic Radiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich (Switzerland); Goetti, Robert; Baumueller, Stephan [Institute of Diagnostic Radiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich (Switzerland); Plass, Andre; Falk, Volkmar [Clinic for Cardiovascular Surgery, University Hospital Zurich (Switzerland); Scheffel, Hans; Feuchtner, Gudrun; Marincek, Borut [Institute of Diagnostic Radiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich (Switzerland); Alkadhi, Hatem [Institute of Diagnostic Radiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich (Switzerland); Cardiac MR PET CT Program, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Leschka, Sebastian [Institute of Diagnostic Radiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich (Switzerland)

    2011-07-15

    Objective: To compare, in patients with suspicion of coronary artery disease (CAD) and low heart rates, image quality, diagnostic performance, and radiation dose values of prospectively and retrospectively electrocardiography (ECG)-gated dual-source computed tomography coronary angiography (CTCA) for the diagnosis of significant coronary stenoses. Materials and methods: Two-hundred consecutive patients with heart rates {<=}70 bpm were retrospectively enrolled; 100 patients undergoing prospectively ECG-gated CTCA (group 1) and 100 patients undergoing retrospectively-gated CTCA (group 2). Coronary artery segments were assessed for image quality and significant luminal diameter narrowing. Sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV), and accuracy of both CTCA groups were determined using conventional catheter angiography (CCA) as reference standard. Radiation dose values were calculated. Results: Both groups were comparable regarding gender, body weight, cardiovascular risk profile, severity of CAD, mean heart rate, heart rate variability, and Agatston score (all p > 0.05). There was no significant difference in the rate of non-assessable coronary segments between group 1 (1.6%, 24/1404) and group 2 (1.4%, 19/1385; p = 0.77); non-diagnostic image quality was significantly (p < 0.001) more often attributed to stair step artifacts in group 1. Segment-based sensitivity, specificity, PPV, NPV, and accuracy were 98%, 98%, 88%, 100%, and 100% among group 1; 96%, 99%, 90%, 100%, and 98% among group 2, respectively. Parameters of diagnostic performance were similar (all p > 0.05). Mean effective radiation dose of prospectively ECG-gated CTCA (2.2 {+-} 0.4 mSv) was significantly (p < 0.0001) smaller than that of retrospectively ECG-gated CTCA (8.1 {+-} 0.6 mSv). Conclusion: Prospectively ECG-gated CTCA yields similar image quality, performs as accurately as retrospectively ECG-gated CTCA in patients having heart rates {<=}70 bpm

  1. 256层CT冠状动脉造影中前瞻性心电门控技术的应用价值%Application Value of Prospective ECG-gated 256-slice CT Coronary Angiography

    Institute of Scientific and Technical Information of China (English)

    李佩玲; 李菁菁; 谢秀丽; 徐克

    2012-01-01

    Objective To explore the application value and limitation of prospective ECG-gated 256-slice CT coronary angiography by comparing image quality and patient radiation dose received by prospective ECG-gated scan with those obtained by retrospective ECG-gated scan. Methods A total of 193 cases were collected in this study. 90 cases accepted prospective ECG-gated 256-slice CT coronary angiography (group A) and 103 cases accepted retrospective ECG-gated scan as a contrast group (group B). The CT dose index of volume,length of scan field were recorded immediately after scan and the dose length product and effective radiation dose (ED) were calculated. Post processing methods included volume rendering,curved planar reconstruction and multiplanar reconstruction. Each coronary segment was scored according to the post-processed image quality. Results The mean ED in group A with an average heart rate of 69 bpm was (4.11 ±1.36) mSv and that in group B with an average heart rate of 78 bpm (12.10±5.62) mSv. The evaluable rate in group A was 94.1% and that in group B was 93.6%. There was statistically significant difference in the mean ED (P 0.05) between group A and group B. Conclusion Prospective ECG-gated 256-slice CT coronary angiography could keep satisfactory image quality and reduce radiation dose. It should be used in clinic at the most if the heart rate adaptive.%目的 通过比较256层CT前瞻性与回顾性心电门控冠状动脉造影的图像质量和辐射剂量,探讨前瞻性心电门控在冠状动脉造影中的应用价值和限度.方法 收集接受冠状动脉CT造影检查并采用前瞻性心电门控扫描者90例,采用回顾性心电门控扫描者103例.扫描时记录容积剂量指数及扫描野长度,计算剂量长度乘积和有效辐射剂量.所有患者均采用容积重建、曲面重建及多平面重建等后处理技术,对各冠状动脉节段的图像质量进行评分.结果 前瞻性心电门控扫描组和回顾性心电门控

  2. The Effectiveness of Non-ECG-Gated Contrast-Enhanced Computed Tomography for the Diagnosis of Non-ST Segment Elevation Acute Coronary Syndrome.

    Science.gov (United States)

    Watanabe, Tomomi; Furuse, Yoshiyuki; Ohta, Yasutoshi; Kato, Masahiko; Ogawa, Toshihide; Yamamoto, Kazuhiro

    2016-09-28

    Non-ST segment elevation acute coronary syndrome (NSTE-ACS) can be difficult to diagnose accurately, especially in the hyper-acute phase. Non-ECG-gated contrast-enhanced computed tomography (non-ECG-gated CE-CT) has been used in many institutions for screening acute chest pain. Although early defects (EDs) observed in non-ECG-gated CE-CT have been reported as a sign of acute myocardial ischemia, the precise diagnostic value of this sign for acute coronary syndrome has not been fully elucidated. We investigated the usefulness of non-ECG-gated CE-CT for the diagnosis of NSTE-ACS. We retrospectively reviewed 556 patients who were hospitalized for acute-onset chest pain and who underwent emergent coronary angiography. Non-ECG-gated CE-CT was performed in 23 of these patients. Two readers independently analyzed CT images using a 5-point scale. Of the 23 patients, 13 were diagnosed with NSTE-ACS. The remaining 10 patients were diagnosed with other conditions. The sensitivity, specificity, positive predictive value, and negative predictive value, respectively, of EDs on non-ECG-gated CE-CT to detect NSTE-ACS were 84.6%, 90%, 91.7%, and 81.8%. The identification of EDs was consistent between the two readers. Non-ECG-gated CE-CT may be useful not only to triage patients with chest pain by ruling out other conditions, but also to accurately diagnose NSTE-ACS.

  3. Non-enhanced ECG-gated respiratory-triggered 3-D steady-state free-precession MR angiography with slab-selective inversion: initial experience in visualisation of renal arteries in free-breathing children without renal artery abnormality

    Energy Technology Data Exchange (ETDEWEB)

    Klee, Dirk; Lanzman, Rotem Shlomo; Blondin, Dirk; Antoch, Gerald; Schaper, Joerg [University Duesseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Duesseldorf (Germany); Schmitt, Peter [Siemens Healthcare, Erlangen (Germany); Oh, Jun [University Children' s Hospital Duesseldorf, Department of General Pediatrics, Duesseldorf (Germany); University Medical Center Hamburg-Eppendorf, Department of Pediatrics, Pediatric Nephrology, Hamburg (Germany); Salgin, Burak; Mayatepek, Ertan [University Children' s Hospital Duesseldorf, Department of General Pediatrics, Duesseldorf (Germany)

    2012-07-15

    ECG-gated non-enhanced balanced steady-state free precession (bSSFP) MR angiography requires neither breath-holding nor administration of contrast material. To investigate the image quality of free-breathing ECG-gated non-enhanced bSSFP MR angiography of renal arteries in children. Fourteen boys and seven girls (mean age, 9.7 years; range, 7 weeks-17 years) with no history of renovascular disease were included. MRI was performed at 1.5 T. Subjective image quality of axial and coronal maximum-intensity-projection reconstructions of four segments (I, aorta and renal artery ostium; II, main renal artery; III, segmental branches; IV, intrarenal vessels) was evaluated using a 4-point scale (4 = excellent, 3 = good, 2 = acceptable, 1 = non-diagnostic). Image quality was excellent for segments I (mean {+-} SD, 3.9 {+-} 0.3) and II (4.0 {+-} 0.1), good for segment III (3.4 {+-} 0.9) and acceptable for segment IV (2.3 {+-} 1.1). Mean image quality did not differ between sedated and non-sedated children. bSSFP MR angiography enables visualisation of renal arteries in children. (orig.)

  4. The impact of hypertension on diastolic left ventricular function, evaluated by quantitative ECG-gated myocardial perfusion SPECT

    Directory of Open Access Journals (Sweden)

    Mohamed H.M. Sayed

    2015-09-01

    Conclusions: Quantitative ECG-gated Tc-99m tetrofosmin SPECT reveals that hypertensive patients with preserved global LV systolic function may have significant changes in diastolic LV function. Gated myocardial perfusion SPECT reports are always lacking in these changes in diastolic function. We recommend inclusion of such changes in diastolic function in gated myocardial perfusion SPECT reports that can help in proper management of hypertensive patients.

  5. Assessment of left ventricular performance by ECG-gated SPECT. Comparison with magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tadamura, Eiji; Inubushi, Masayuki; Kubo, Shigeto; Matsumoto, Keiichi; Yokoyama, Hiroshi; Fujita, Toru; Konishi, Junji [Kyoto Univ. (Japan). Faculty of Medicine

    1999-10-01

    In the measurement of a left ventricular volume, MIBI-QGS was compared with MRI. Because it became clear by the experiment using phantom that a volume calculated with QGS was smaller than the actual volume, data of clinical study were corrected. Subjects were 20 patients with coronary artery disease. Fourteen patients had anamnesis of myocardial infarct. ECG-gated SPECT was performed one hour after intravenous injection of MIBI (600 MBq) in rest. End diastolic volume (EDV), end systolic volume (ESV) and ejection fraction (EF) were calculated using QGS. Cine-MR image was obtained by using MR system of 1.5 Tesla within 1 week after SPECT. A condition was as follows; segmented k-space gradient echo with view sharing, TR=11 ms, TE=1.4 ms, flip angle 20 degree, field of view 32 cm, matrix 256 x 196, 8 lines per segment. LVEF, ESV and EF were analysed by Bland-Altman method, and the difference between MIBI-gated-SPECT and MRI was no problem. Horizontal dislocation image and vertical major axis dislocation image were provided. Minor axis crossing images of 10-12 slice were also filmed in order to cover all left ventricles. As a result, availability of MIBI-QGS became clear. Some factors which produces the measurement error are examined. (K.H.)

  6. Low-dose ECG-gated 64-slices helical CT angiography of the chest: evaluation of image quality in 105 patients

    Energy Technology Data Exchange (ETDEWEB)

    D' Agostino, A.G.; Remy-Jardin, M.; Khalil, C.; Remy, J. [University Center of Lille, Department of Thoracic Imaging, Hospital Calmette, Lille (France); Delannoy-Deken, V.; Duhamel, A. [University of Lille, Department of Medical Statistics, Lille (France); Flohr, T. [Siemens Medical, Research and Development Department, CT Division, Forchheim (Germany)

    2006-10-15

    The purpose of this study was to evaluate image quality of low-dose electrocardiogram (ECG)-gated multislice helical computed tomography (CT) angiograms of the chest. One hundred and five consecutive patients with a regular sinus rhythm (72 men; 33 women) underwent ECG-gated CT angiographic examination of the chest without administration of beta blockers using the following parameters: (a) collimation 32 x 0.6 mm with z-flying focal spot for the acquisition of 64 overlapping 0.6-mm slices, rotation time 0.33 s, pitch 0.3; (b) 120 kV, 200 mAs; (c) use of two dose modulation systems, including adjustment of the mAs setting to the patient's size and anatomical shape and an ECG-controlled tube current. Subjective and objective image quality was evaluated by two radiologists in consensus on 3-mm-thick scans reconstructed at 55% of the response rate (RR) interval. The population and protocol characteristics included: (a) a mean [{+-}standard deviation (SD)] body mass index (BMI) of 24.47 ({+-}4.64); (b) a mean ({+-}SD) heart rate of 72.04 ({+-}15.76) bpm; (c) a mean ({+-}SD) scanning time of 18.3 ({+-}2.73) s; (d) a mean ({+-}SD) dose-length product (DLP) value of 260.57 ({+-}83.67) mGy/cm; (e) an estimated average effective dose of 4.95 ({+-}1.59) mSv. Subjective noise was depicted in a total of nine examinations (8.5%), always rated as mild. Objective noise was assessed by measuring the standard deviation of pixel values in a homogeneous region of interest within the trachea and descending aorta; SD was 15.91 HU in the trachea and 22.16 HU in the descending aorta, with no significant difference in the mean value of the standard deviations between the four categories of BMI except for obese patients, who had a higher mean SD within the aorta. Interpolation artefacts were depicted in 22 patients, with a mean heart rate significantly lower than that of patients without interpolation artifacts, rated as mild in 11 patients and severe in 11 patients. The severity of

  7. Interobserver agreement for the detection of atherosclerotic plaque in coronary CT angiography: comparison of two low-dose image acquisition protocols with standard retrospectively ECG-gated reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Schuhbaeck, Annika; Rixe, Johannes; Hamm, Christian [University of Giessen, Department of Cardiology, Giessen (Germany); Marwan, Mohamed; Gauss, Soeren; Muschiol, Gerd; Ropers, Dieter; Daniel, Werner G.; Achenbach, Stephan [University of Erlangen, Department of Cardiology, Erlangen (Germany); Schneider, Christian [University of Giessen, Department of Radiology, Giessen (Germany); Lell, Michael [University of Erlangen, Department of Radiology, Erlangen (Germany)

    2012-07-15

    We compared the interobserver variability concerning the detection of calcified and non-calcified plaque in two different low-dose and standard retrospectively gated protocols for coronary CTA. 150 patients with low heart rates and less than 100 kg body weight were randomised and examined by contrast-enhanced dual-source CT coronary angiography (100 kV, 320 mAs). 50 patients were examined with prospectively ECG-triggered axial acquisition, 50 patients with prospectively ECG-triggered high pitch spiral acquisition, and 50 patients using spiral acquisition with retrospective ECG gating. Two investigators independently analysed the datasets concerning the presence of calcified and non-calcified plaque on a per-segment level. Mean effective dose was 1.4 {+-} 0.2 mSv for axial, 0.8 {+-} 0.07 mSv for high-pitch spiral, and 5.3 {+-} 2.6 mSV for standard spiral acquisition (P < 0.0001). In axial acquisition, interobserver agreement concerning the presence of atherosclerotic plaque was achieved in 650/749 coronary segments (86.8%). In high-pitch spiral acquisition, agreement was achieved in 664/748 segments (88.8%, n.s.). In standard spiral acquisition, agreement was achieved in 672/738 segments (91.0%, P < 0.0001). Interobserver agreement was significantly higher for calcified than for non-calcified plaque in all data acquisition modes. Low-dose coronary CT angiography permits the detection of coronary atherosclerotic plaque with good interobserver agreement. (orig.)

  8. Coronary artery aneurysm and type-A aortic dissection demonstrated by retrospectively ECG-gated multislice spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Fallenberg, Eva Maria; Juergens, Kai Uwe; Fischbach, Roman [Department of Clinical Radiology, University Hospital Muenster (Germany); Wichter, Thomas [Department of Cardiology and Angiology, University Hospital Muenster (Germany); Scheld, Hans H. [Department of Thoracic and Cardiovascular Surgery, University Hospital Muenster (Germany)

    2002-01-01

    The case of a 40-year-old male patient with a coronary aneurysm of the proximal left descending artery (LAD) combined with circumferential type-A dissection of the ascending aorta is reported. Computed tomography angiography of the coronary arteries was performed using multislice spiral computed tomography (MSCT) with retrospective ECG gating. Anatomical relations of the LAD aneurysm as well as the origin of the left coronary artery from the false lumen of the dissection were well depicted for planning of the surgical intervention using this new noninvasive imaging modality. (orig.)

  9. Impact of ECG gating in contrast-enhanced MR angiography for the assessment of the pulmonary veins and the left atrium anatomy

    Energy Technology Data Exchange (ETDEWEB)

    Katoh, M.; Buecker, A.; Muehlenbruch, G.; Guenther, R.W.; Spuentrup, E. [Klinik fuer Radiologische Diagnostik, Universitaetsklinikum RWTH Aachen (Germany); Schauerte, P. [Medizinische Klinik 1, Universitaetsklinikum RWTH Aachen (Germany)

    2006-02-15

    Purpose: Implementation of ECG gating in contrast-enhanced MR angiography (ceMRA) for improved visualization of the pulmonary veins, the left atrium, and the thoracic vessels. Materials and Methods: CeMRA was performed on twelve patients with a history of recurrent atrial fibrillation for the purpose of an intra-individual comparison with and without ECG gating on a 1.5 Tesla MR system (Gyroscan Intera, Philips Medical Systems, Best, NL). Objective image quality parameters such as the signal-to-noise ratio (SNR) of the blood and the contrast-to-noise ratio (CNR) between the blood and myocardium or lung parenchyma were analyzed. The contour sharpness of the pulmonary veins, left atrium, ascending aorta, and pulmonary trunk was also measured. In addition, the artifact level was subjectively assessed by two observers blinded with respect to the sequence parameters. Statistically significant differences (p<0.05) between the procedures were analyzed using the Wilcoxon test and Pearson Chi-square test. Results: The use of ECG gating in ceMRA significantly reduced artifacts caused by cardiac motion and vessel pulsation. This in turn lead to a significant increase in the contour sharpness of the left atrium and the thoracic vessels. In addition, higher SNR and CNR were found using ECG-gated ceMRA compared to standard ceMRA. Conclusion: The use of ECG gating in ceMRA results in artifact-free and sharper delineation of the structures of the heart and thoracic vessels. (orig.)

  10. Computer-based automated left atrium segmentation and volumetry from ECG-gated coronary CT angiography data. Comparison with manual slice segmentation and ultrasound planimetric methods

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, R.W.; Kraus, B.; Kerl, J.M.; Lehnert, T.; Vogl, T.J. [Universitaetsklinikum Frankfurt (Germany). Inst. fuer Diagnostische und Interventionelle Radiologie; Bernhardt, D.; Vega-Higuera, F. [Siemens AG, Healthcare Sector, Forchheim (Germany). Computed Tomography; Ackermann, H. [Universitaetsklinikum Frankfurt (Germany). Inst. fuer Biostatistik und Mathematische Modellierung

    2010-12-15

    Purpose: Enlargement of the left atrium is a risk factor for cardiovascular or cerebrovascular events. We evaluated the performance of prototype software for fully automated segmentation and volumetry of the left atrium. Materials and Methods: In 34 retrospectively ECG-gated coronary CT angiography scans, the end-systolic (LAVsys) and end-diastolic (LAVdia) volume of the left atrium was calculated fully automatically by prototype software. Manual slice segmentation by two independent experienced radiologists served as the reference standard. Furthermore, two independent observers calculated the LAV utilizing two ultrasound planimetric methods ('area length' and 'prolate ellipse') on CTA images. Measurement periods were compared for all methods. Results: The left atrial volumes calculated with the prototype software were in excellent agreement with the results from manual slice segmentation (r = 0.97 - 0.99; p < 0.001; Bland-Altman) with excellent interobserver agreement between both radiologists (r = 0.99; p < 0.001). Ultrasound planimetric methods clearly showed a higher variation (r = 0.72 - 0.86) with moderate interobserver agreement (r = 0.51 - 0.79). The measurement period was significantly lower with the software (267 {+-} 28 sec; p < 0.001) than with ultrasound methods (431 {+-} 68 sec) or manual slice segmentation (567 {+-} 91 sec). Conclusion: The prototype software showed excellent agreement with manual slice segmentation with the least time consumption. This will facilitate the routine assessment of the LA volume from coronary CTA data and therefore risk stratification. (orig.)

  11. 心电门控CTA评价急性主动脉夹层的临床应用研究%Clinical Application of ECG Gated CTA in Evaluation of Acute Aortic Dissection

    Institute of Scientific and Technical Information of China (English)

    陈凤丽; 刘挨师

    2016-01-01

    Objective: In this study, we would compare to the routine aorta CTA and ECG gated aorta CTA image quality, in order to know the advantage of ECG gated aorta CTA in evaluation of aortic dissection. Methods:Through the imaging system retrospectively selected 62 patients who underwent aorta CTA from 2013 January to 2016 March, divided into two groups. Group A underwent triple rule out scanning (13 cases), group B underwent aortic CTA (49 cases). Evaluation of aortic image quality and assessment of various indexes of aortic dissection. The measurement data were compared by two independent samplesttest, and count data were compared using chi-square test. A(P0.05). Conclusions: Applying the ECG gated aortic CTA compared with the conventional spiral aorta CTA, it could clearly displaythe index of aortic dissection, evaluate prognosis ofaortic dissection, guide the therapy and formulate operation /endovascular treatment plan.%目的:本研究通过主动脉CTA与胸痛三联排查扫描(心电门控)CTA主动脉图像质量的比较,明确施加心电门控的 CTA 在临床选择与评价主动脉夹层治疗方案中的价值。方法:通过影像数据存储与传输系统(PACS)回顾性选取2013年1月至2016年3月间行胸痛三联排查与主动脉CTA 的患者62例,分为两组,A 组行胸痛三联排查扫描(13例),B 组行主动脉 CTA(49例)。评价主动脉图像质量与主动脉夹层各项指标可评估性。计量资料比较采用两独立样本t检验,计数资料比较采用χ2检验。P0.05)。结论:施加心电门控的主动脉CTA较常规螺旋扫描主动脉CTA可以更加清晰地显示主动脉夹层各项指标,在进行疾病预后评估、指导治疗方案与制定手术/血管内治疗计划中具有一定作用。

  12. Quantification of aortic distensibility in abdominal aortic aneurysm using ECG-gated multi-detector computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ganten, Maria-Katharina [Deutsches Krebsforschungszentrum, Department of Radiology, Medical Physics in Radiology, Heidelberg (Germany); Ruprecht-Karls-University of Heidelberg, Department of Diagnostic Radiology, Heidelberg (Germany); Krautter, Ute; Tengg-Kobligk, Hendrik von; Delorme, Stefan; Kauczor, Hans-Ulrich [Deutsches Krebsforschungszentrum, Department of Radiology, Medical Physics in Radiology, Heidelberg (Germany); Boeckler, Dittmar; Schumacher, Hardy [Ruprecht-Karls-University of Heidelberg, Department of Vascular and Endovascular Surgery, Heidelberg (Germany); Stiller, Wolfram; Bock, Michael [Deutsches Krebsforschungszentrum, Department of Medical Physics in Radiology, Medical Physics in Radiology, Heidelberg (Germany); Kauffmann, Guenter W. [Ruprecht-Karls-University of Heidelberg, Department of Diagnostic Radiology, Heidelberg (Germany)

    2008-05-15

    To detect distensibility changes that might be an indicator for an increased risk of rupture, cross-sectional area changes of abdominal aortic aneurysms (AAA) have been determined using ECG-gated CT. Distensibility measurements of the aorta were performed in 67 patients with AAA. Time-resolved images were acquired with a four detector-row CT system using a modified CT-angiography protocol. Pulsatility-related cross-sectional area changes were calculated above and at AAA level by semiautomatic segmentation; distensibility values were obtained using additional systemic blood pressure measurements. Values were compared for small Oe< 5 cm (n=44) and large Oe> 5 cm (n = 23) aneurysms. The aorta could be segmented successfully in all patients. Upstream AAA distensibility D was significantly higher than at AAA level for both groups: means above AAA (at AAA) D{sub above} = (1.3 {+-}0.8) .10 {sup -5} Pa {sup -1} (D{sub AAA} = (0.6 {+-}0.5) .10 {sup -5} Pa {sup -1}) t-test p{sub D}<0.0001. Differences of the distensibility between smaller and larger aneurysms were not found to be significant. Distensibility can be measured non-invasively with ECG-gated CT. The reduction of distensibility within aneurysms compared to normal proximal aorta is subtle; the lack of difference between both small and large aneurysms suggests that this reduction occurs early in the aneurysm's development. Hence, reduced distensibility might be a predictive parameter in patients with high risk of aortic disease. (orig.)

  13. Validation of an image registration and segmentation method to measure stent graft motion on ECG-gated CT using a physical dynamic stent graft model

    Science.gov (United States)

    Koenrades, Maaike A.; Struijs, Ella M.; Klein, Almar; Kuipers, Henny; Geelkerken, Robert H.; Slump, Cornelis H.

    2017-03-01

    The application of endovascular aortic aneurysm repair has expanded over the last decade. However, the long-term performance of stent grafts, in particular durable fixation and sealing to the aortic wall, remains the main concern of this treatment. The sealing and fixation are challenged at every heartbeat due to downward and radial pulsatile forces. Yet knowledge on cardiac-induced dynamics of implanted stent grafts is sparse, as it is not measured in routine clinical follow-up. Such knowledge is particularly relevant to perform fatigue tests, to predict failure in the individual patient and to improve stent graft designs. Using a physical dynamic stent graft model in an anthropomorphic phantom, we have evaluated the performance of our previously proposed segmentation and registration algorithm to detect periodic motion of stent grafts on ECG-gated (3D+t) CT data. Abdominal aortic motion profiles were simulated in two series of Gaussian based patterns with different amplitudes and frequencies. Experiments were performed on a 64-slice CT scanner with a helical scan protocol and retrospective gating. Motion patterns as estimated by our algorithm were compared to motion patterns obtained from optical camera recordings of the physical stent graft model in motion. Absolute errors of the patterns' amplitude were smaller than 0.28 mm. Even the motion pattern with an amplitude of 0.23 mm was measured, although the amplitude of motion was overestimated by the algorithm with 43%. We conclude that the algorithm performs well for measurement of stent graft motion in the mm and sub-mm range. This ultimately is expected to aid in patient-specific risk assessment and improving stent graft designs.

  14. 心率对256层CT前瞻性心电门控冠状动脉成像质量的影响%Prospectively ECG-gated coronary angiograhpy with 256-slice CT:impact of heart rate on image quality

    Institute of Scientific and Technical Information of China (English)

    张晓东; 赖紫霞; 唐秉航; 李芳云; 李良才; 黄晖; 何亚奇; 吴任国; 黄德成; 梁建雄

    2011-01-01

    运动伪影的临界点。256层螺旋CT前瞻性心电门控技术具有广阔的应用空间。%Objective:To investigate the impact of heart rate on image quality with prospectively ECG-gated coronary artery angiography (CAA) using a 256-slice CT.and compared with retrospectively-ECG-gated CAA. Methods:Prospectively electrocardiography (ECG)-gated CAA was performed in 156 patients and retrospectively ECG-gated CAA was performed in 73 patients. The two scan modes were divided into six groups with the heart rate as 0. 05). Using retrospectively ECG-gated scan,the image quality of CA segments as excellent and good (score 1 and 2) in each group was 100% ,95% ,90% ,88% ,92% and 49% respectively,showing significant differences between different heart rate groups (P<0. 05). Image quality of coronary segments fulfilled the requirement of diagnosis in each group was 100%, 99% , 98%, 98%, 98% and 100% respectively with prospectively-ECG-gated scan, and 100%, 100%,99%, 100%, 100% and 96% respectively with retrospectively ECG-gated scan. Apart from the mean heart rate as 80~89b/m,the diagnostic image quality for coronary segments between prospective ECG-gated mode and retrospectively-ECG-gated mode showed no significant difference. With prospectively ECG-gated scan mode,significant correlation of mean heart rate and motion artifact was revealed on ROC analysis (AUC=0. 783;95% CI:0. 709,0. 856;F<0. 01). Conclusion: Using prospectively ECG-gated mode of CAA with 256-slice CT.mean heart rate did not show significant correlation with image quality,and similar diagnostic image quality could be acquired with that of using retrospectively ECG-gated mode. Appearance of motion artifact of CA could be affected by mean heart rate,heart beat as 65. 5b/m could be used as the critical point of the occurrence of motion artifact of CA. Prospectively ECG-gated CAA with 256-slice CT could be used commonly for coronary angiography in clinical practice.

  15. Pulmonary artery and right ventricle assessment in pulmonary hypertension. Correlation between functional parameters of ECG-gated CT and right-side heart catheterization

    Energy Technology Data Exchange (ETDEWEB)

    Abel, Elodie; Jankowski, Adrien [Clinique univ. de radiologie et imagerie medicale, CHU Grenoble (France); Pison, Christophe [Clinique univ. de pneumologie, CHU Grenoble (France); Bosson, Jean Luc [Dept. of Statistics, CIC, CHU Grenoble (France); Bouvaist, Helene [Clinique univ. de cardiologie, CHU Grenoble (France); Ferretti, Gilbert R. [Clinique univ. de radiologie et imagerie medicale, CHU Grenoble (France); Univ. J. Fourier, Grenoble (France); INSERM U 823, Inst. A. Bonniot, la Tronche (France)], e-mail: gferretti@chu-grenoble.fr

    2012-09-15

    Background: Right ventricular function predicts outcome in patients with pulmonary hypertension (PH). Therefore accurate assessment of right ventricular function is essential to graduate severity, assess follow-up, and response to therapy. Purpose: To evaluate whether PH severity could be assessed using electrocardiography-gated CT (ECG-gated CT) functional parameters. A further objective was to evaluate cardiac output (CO) using two ECG-gated CT methods: the reference Simpson technique and the fully automatic technique generated by commercially available cardiac software. Material and Methods: Our institutional review board approved this study; patient consent was not required. Twenty-seven patients who had undergone ECG-gated CT and right heart catheterization (RHC) were included. Two independent observers measured pulmonary artery (PA) diameter, PA distensibility, aorta diameter, right ventricular cardiac output (CT-RVCO) and right ventricular ejection fraction (CT-RVEF) with automatic and Simpson techniques on ECG-gated CT. RHC-CO and mean pulmonary arterial pressure (mPAP) were measured on RHC. Relationship between ECG-gated CT and RHC measurements was tested with linear regression analysis. Results: Inter-observer agreement was good for all measurements (r > 0.7) except for CT-RVCO calculated with Simpson's technique (r = 0.63). Pulmonary artery (PA) distensibility was significantly correlated to mPAP (r = -0.426, P = 0.027). CT-RVEF was correlated with mPAP only when issued from Simpson technique (r = -0.417, P = 0.034). CT-RVEF was not significantly correlated to RHC-CO (P > 0.2). CT-RVCO measured with Simpson technique (r = 0.487, P = 0.010) and automatic segmentation (r = 0.549, P 0.005) correlated equally with RHC-CO. Conclusion: CT-RVEF and CT-RVCO measured on ECG-gated CT are significantly correlated, respectively, to mPAP and RHC-CO in this population with severe reduction of the right ventricular ejection fraction and could be useful for

  16. Non-invasive assessment of coronary artery bypass graft with retrospectively ECG-gated four-row multi-detector spiral computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Marano, Riccardo; Storto, Maria Luigia; Maddestra, Nicola; Bonomo, Lorenzo [Department of Clinical Sciences and Bioimaging, Section of Radiology, University ' ' G. d' Annunzio' ' , Ospedale ' ' SS. Annunziata' ' , Via dei Vestini, 66100, Chieti (Italy)

    2004-08-01

    The purpose of this study was to assess the accuracy of four-row multi-detector CT (MDCT) in the evaluation of coronary artery bypass graft (CABG) in patients with at least a left internal mammary artery (LIMA) grafted to the left anterior descending artery (LAD), because of the conduit of choice in bypass surgery and the greater difficulty of evaluation with non-invasive diagnostic tools. Included in the study were 57 patients with a total of 122 grafts (95 arterial and 27 venous) who underwent MDCT (4 x 2.5-mm detector-collimation, 3-mm slice width, 1.5-mm reconstruction increment) with retrospective ECG gating. Twelve patients (21%) with high heart rates were given beta-blockers in order to obtain a heart rate {<=}70 bpm in all patients. The ECG-synchronized axial images, reconstructed in the mid-diastole, MPR, MIP and 3D-VR images were independently and blindly assessed by two radiologists for graft patency and presence of high grade stenosis. Conventional angiography was the standard of reference. MDCT correctly classified 92/94 patent grafts and 26/28 occluded grafts (sensitivity/specificity 93%/97.8%); sensitivity and specificity of MDCT for assessment of arterial grafts were 100 and 98.7% (77/78 patent grafts and 17/17 occluded grafts). Image quality was considered adequate for assessment of significant stenoses in 62/92 (67%) patent grafts, with a significant differences between LIMA and non-LIMA conduits (44/57 vs. 18/65; P=0.002), according to the coronary vessel area supplied (anterior>lateral>posterior-inferior wall; P=0.002). In the remaining 30 patent grafts (33%), the assessment of stenoses was hampered by surgical clips, calcifications and motion artifacts. Sensitivity and specificity of MDCT for detection of significant graft stenoses were 80 and 96%, respectively. Inter-observer agreement was good (K=0.73). MDCT seems to be a valuable diagnostic tool for non-invasive assessment of patency of both venous and arterial grafts. An accurate evaluation

  17. Prospective ECG triggering versus low-dose retrospective ECG-gated 128-channel CT coronary angiography: comparison of image quality and radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Q.; Yin, Y.; Hua, X.; Zhu, R.; Hua, J. [Department of Radiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai (China); Xu, J., E-mail: xujianr@hotmail.co [Department of Radiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai (China)

    2010-10-15

    Aim: To evaluate image quality and radiation dose for 128-detector prospective electrocardiogram (ECG)-gated computed tomography coronary angiography (CTCA) compared with a low-dose retrospective ECG-gated imaging protocol. Materials and methods: Thirty-one and 47 patients suspected of having coronary artery disease were enrolled into groups examined using prospective and low-dose retrospective ECG-gated CT protocols respectively. All examinations were performed on a 128-detector CT system (Definition AS, Siemens Healthcare, Forchheim, Germany). Prospective CTCA was performed using following parameters: tube voltage 100 kV; tube current 205 mAs; centre of acquisition window 70% of the RR interval. The tube current for low-dose retrospective ECG-gated CTCA was full dose during 40-70% of the RR interval and partial dose for the rest of RR interval. The pitch varied between 0.2 and 0.5 depending on heart rate and patient size. Image quality of coronary arteries was evaluated using a four-point grading scale. The signal-to-noise ratios (SNRs) of enhanced arteries and myocardium were also measured, corresponding contrast-to-noise ratios (CNRs) were calculated, and the radiation doses received were recorded. Results: There was a significant difference in the image quality scores between the retrospective and prospective gating protocols (Chi-square = 15.331, p = 0.009). There was no significant difference between the SNRs of the contrasted artery and myocardium in these two groups, but the CNRs were increased in the prospective group. The mean radiation dose of prospective gating group was 2.71 {+-} 0.67 mSv (range, 1.67-3.59 mSv), which was significantly lower than that of the retrospective group (p < 0.001). Conclusion: Prospective CT angiography can achieve lower radiation dose than that of low-dose retrospective CT angiography, with preserved image quality.

  18. Assessment of Double Outlet Right Ventricle Associated with Multiple Malformations in Pediatric Patients Using Retrospective ECG-Gated Dual-Source Computed Tomography.

    Directory of Open Access Journals (Sweden)

    Ke Shi

    Full Text Available To evaluate the feasibility and diagnostic accuracy of retrospective electrocardiographically (ECG-gated dual-source computed tomography (DSCT for the assessment of double outlet right ventricle (DORV and associated multiple malformations in pediatric patients.Forty-seven patients <10 years of age with DORV underwent retrospective ECG-gated DSCT. The location of the ventricular septal defect (VSD, alignment of the two great arteries, and associated malformations were assessed. The feasibility of retrospective ECG-gated DSCT in pediatric patients was assessed, the image quality of DSCT and the agreement of the diagnosis of associated malformations between DSCT and transthoracic echocardiography (TTE were evaluated, the diagnostic accuracies of DSCT and TTE were referred to surgical results, and the effective doses were calculated.Apart from DORV, 109 associated malformations were confirmed postoperatively. There was excellent agreement (κ = 0.90 for the diagnosis of associated malformations between DSCT and TTE. However, DSCT was superior to TTE in demonstrating paracardiac anomalies (sensitivity, coronary artery anomalies: 100% vs. 80.00%, anomalies of great vessels: 100% vs. 88.57%, separate thoracic and abdominal anomalies: 100% vs. 76.92%, respectively. Combined with TTE, DSCT can achieve excellent diagnostic performance in intracardiac anomalies (sensitivity, 91.30% vs. 100%. The mean image quality score was 3.70 ± 0.46 (κ = 0.76. The estimated mean effective dose was < 1 mSv (0.88 ± 0.34 mSv.Retrospective ECG-gated DSCT is a better diagnostic tool than TTE for pediatric patients with complex congenital heart disease such as DORV. Combined with TTE, it may reduce or even obviate the use of invasive cardiac catheterization, and thus expose the patients to a much lower radiation dose.

  19. The effect of relaxing music on heart rate and heart rate variability during ECG GATED-myocardial perfusion scintigraphy.

    Science.gov (United States)

    Tan, Yusuf Ziya; Ozdemir, Semra; Temiz, Ahmet; Celik, Fatmanur

    2015-05-01

    The positive changes in human behavior caused by relaxing music demonstrate the psychological effect of music on human body. A meta-analytical study has shown that relaxing music affects blood pressure and heart rate in coronary heart patients and cancer patients. The aim of our study is to research whether there is a significant effect on heart rate and heart rate variability due to listening to relaxing music during ECG GATED MPS imaging under gamma camera. The music group (n = 50 patients) could choose from 15 different musical types including folk music (no lyric). The other 50 patients were placed in a "no music group" and did not get headphones or any music. There was a statistically significant reduction in the heart rate of patients in the music group compared to those in the control group. Relaxing music provides great benefits to both patient and clinician. There is close relationship between relaxing music and health procedure, can use every area of the health noninvasiv, safe, cheap and is a method don't have side effect. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Diagnostic value of ECG-gated multidetector computed tomography in the early phase of suspected acute myocarditis. A preliminary comparative study with cardiac MRI

    Energy Technology Data Exchange (ETDEWEB)

    Dambrin, Gregoire; Caussin, Christophe; Lancelin, Bernard; Paul, Jean F. [Centre Chirurgical Marie Lannelongue, Departments of Cardiology and Radiology, Le Plessis Robinson (France); Laissy, Jean P.; Serfaty, Jean M. [AP-HP, Hospital Bichat, Department of Radiology, Paris (France)

    2007-02-15

    The aim of the study was to determine the potential diagnostic value of contrast-enhanced echocardiogram (ECG)-gated multidetector computed tomography (MDCT) in the setting of suspected acute myocarditis compared with contrast-enhanced magnetic resonance imaging (MRI). The study group consisted of 12 consecutive patients admitted for suspected acute myocarditis less than 10 days after onset of symptoms. All patients had clinical, electrocardiographic signs, and laboratory findings consistent with the diagnosis. All patients but one (severe claustrophobia) underwent cardiac MRI using T1-weighted delayed-enhancement images after injection of gadolinium. ECG-gated MDCT was performed in all patients and included a first-pass contrast-enhanced acquisition and a delayed acquisition. MRI revealed abnormal focal or multifocal myocardial enhancement and confirmed the diagnosis in 11 patients. The first-pass MDCT acquisition showed homogenous left-ventricle contrast enhancement and absence of coronary stenosis in all patients. Delayed MDCT acquisition, performed 5 min later without reinjection of contrast medium revealed multiple areas of myocardial hyperenhancement in a focal or a multifocal pattern (six and six patients, respectively). Extent and location of hyperenhancement at MDCT correlated well with that observed at MR examination for all 11 patients evaluated by both techniques (r=0.9167, p=0.0004). These preliminary results show that ECG-gated MDCT could be a useful alternative noninvasive diagnostic test in the early phase of acute myocarditis. (orig.)

  1. The value of low-dose prospective ECG-gated dual-source CT angiography in the diagnosis of coarctation of the aorta in infants and children

    Energy Technology Data Exchange (ETDEWEB)

    Nie, P. [Shandong Provincial Key Laboratory of Diagnosis and Treatment of Cardio-Cerebral Vascular Diseases, Shandong Medical Imaging Research Institute, Shandong University, Jinan, Shandong (China); Wang, X., E-mail: wxming369@yahoo.com.cn [Shandong Provincial Key Laboratory of Diagnosis and Treatment of Cardio-Cerebral Vascular Diseases, Shandong Medical Imaging Research Institute, Shandong University, Jinan, Shandong (China); Cheng, Z.; Duan, Y.; Ji, X. [Shandong Provincial Key Laboratory of Diagnosis and Treatment of Cardio-Cerebral Vascular Diseases, Shandong Medical Imaging Research Institute, Shandong University, Jinan, Shandong (China); Chen, J. [CT Research Collaboration, Siemens, Beijing (China); Zhang, H. [Department of Cardiovascular Surgery, Shandong Provincial Hospital, Jinan, Shandong (China)

    2012-08-15

    Aim: To investigate the value of prospective electrocardiogram (ECG)-gated dual-source computed tomography (DSCT) in the diagnosis of coarctation of the aorta (CoA). Materials and methods: Seventeen patients clinically suspected of having CoA underwent prospective ECG-gated DSCT angiography and transthoracic echocardiography (TTE). Surgery was performed in all patients. The diagnostic accuracy of DSCT angiography and TTE was compared with the surgical findings as the reference standard. Image quality was evaluated using a five-point scale. Effective radiation dose was calculated from the dose-length product (DLP). Results: CoA was diagnosed in 17 patients by DSCT angiography and in 16 patients by TTE. A total of 46 separate cardiovascular abnormalities were confirmed by surgical findings. The diagnostic accuracy of DSCT angiography and TTE was 96.32% and 97.06%, respectively. There was no significant difference in the diagnostic accuracy between DSCT angiography and TTE ({chi}{sup 2} = 0, p > 0.05). The mean score of image quality was 4.2 {+-} 0.8. The mean effective dose was 0.69 {+-} 0.09 mSv. Conclusion: Prospective ECG-gated DSCT with a low radiation dose is a valuable technique in the diagnosis of CoA in infants and children.

  2. Coronary imaging quality in routine ECG-gated multidetector CT examinations of the entire thorax: preliminary experience with a 64-slice CT system in 133 patients

    Energy Technology Data Exchange (ETDEWEB)

    Delhaye, Damien; Remy-Jardin, Martine; Salem, Randa; Teisseire, Antoine; Khalil, Chadi; Remy, Jacques [Hospital Calmette, University Center of Lille, Department of Thoracic Imaging, Lille Cedex (France); Delannoy-Deken, Valerie; Duhamel, Alain [University of Lille, Department of Medical Statistics, Lille Cedex (France)

    2007-04-15

    To evaluate image quality in the assessment of the coronary arteries during routine ECG-gated multidetector CT (MDCT) of the chest. One hundred and thirty three patients in sinus rhythm underwent an ECG-gated CT angiographic examination of the entire chest without {beta}-blockers with a 64-slice CT system. In 127 patients (95%), it was possible to assess the coronary arteries partially or totally; coronary artery imaging failed in six patients (5%), leading to a detailed description of the coronary arteries in 127 patients. Considering ten coronary artery segments per patient, 75% of coronary segments were assessable (948/1270 segments). When the distal segments were excluded from the analysis (i.e., seven coronary segments evaluated per patient), the percentage of assessable segments was 86% (768/889 proximal and mid coronary segments) and reached 93% (474/508) when assessing proximal segments exclusively. The mean number of assessable segments was significantly higher in patients with a heart rate {<=}80 bpm (n=95) than in patients with a heart rate >80 bpm (n=38) (p<0.002). Proximal and mid-coronary segments can be adequately assessed during a whole-chest ECG-gated CT angiographic examination without administration of {beta}-blockers in patients with a heart rate below 80 bpm. (orig.)

  3. Radiation dose in computed tomography of the pelvis: comparison of helical and axial scanning.

    Science.gov (United States)

    Pitman, A G; Budd, R S; McKenzie, A F

    1997-11-01

    An anthropomorphic Rando phantom was used to compare radiation doses sustained during helical and conventional axial CT of the pelvis. The values obtained with the Rando phantom were validated against cadaveric phantoms, and show good agreement. For the authors' particular CT unit, helical scanning was found to deliver a lower radiation dose than conventional axial scanning. This was most prominent at 1.0-s tube rotation times (average dose ratio 1.24). For realistic scanning parameters and exposure factors, the ratio of radiation dose to pelvic organs can be expected to lie in the range of 40-100 mGy. The whole-body effective dose (ED) depends on selection of scanning parameters and patients anatomy. In a favourable case scenario, the ED for CT scanning of the pelvis in a male can be expected to be between 10 and 20 mSv if the scrotum is not included in the radiation field, while the ED in a female will be approximately 20 mSv. An examination of scatter radiation fall-off curves from a single slice shows that the spread of scatter radiation is only marginally affected by slice thickness. A total of 10-12 cm of human soft tissue acts as a good barrier against internal scattered radiation. The use of such scatter fall-off curves, together with manufacturers' dosimetry specifications, allows a fast estimate of absorbed dose.

  4. Erroneous cardiac ECG-gated PET list-mode trigger events can be retrospectively identified and replaced by an offline reprocessing approach: first results in rodents

    Science.gov (United States)

    Böning, Guido; Todica, Andrei; Vai, Alessandro; Lehner, Sebastian; Xiong, Guoming; Mille, Erik; Ilhan, Harun; la Fougère, Christian; Bartenstein, Peter; Hacker, Marcus

    2013-11-01

    The assessment of left ventricular function, wall motion and myocardial viability using electrocardiogram (ECG)-gated [18F]-FDG positron emission tomography (PET) is widely accepted in human and in preclinical small animal studies. The nonterminal and noninvasive approach permits repeated in vivo evaluations of the same animal, facilitating the assessment of temporal changes in disease or therapy response. Although well established, gated small animal PET studies can contain erroneous gating information, which may yield to blurred images and false estimation of functional parameters. In this work, we present quantitative and visual quality control (QC) methods to evaluate the accuracy of trigger events in PET list-mode and physiological data. Left ventricular functional analysis is performed to quantify the effect of gating errors on the end-systolic and end-diastolic volumes, and on the ejection fraction (EF). We aim to recover the cardiac functional parameters by the application of the commonly established heart rate filter approach using fixed ranges based on a standardized population. In addition, we propose a fully reprocessing approach which retrospectively replaces the gating information of the PET list-mode file with appropriate list-mode decoding and encoding software. The signal of a simultaneously acquired ECG is processed using standard MATLAB vector functions, which can be individually adapted to reliably detect the R-peaks. Finally, the new trigger events are inserted into the PET list-mode file. A population of 30 mice with various health statuses was analyzed and standard cardiac parameters such as mean heart rate (119 ms ± 11.8 ms) and mean heart rate variability (1.7 ms ± 3.4 ms) derived. These standard parameter ranges were taken into account in the QC methods to select a group of nine optimal gated and a group of eight sub-optimal gated [18F]-FDG PET scans of mice from our archive. From the list-mode files of the optimal gated group, we

  5. Prospectively ECG-triggered sequential dual-source coronary CT angiography in patients with atrial fibrillation: comparison with retrospectively ECG-gated helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Lei; Yang, Lin; Zhang, Zhaoqi [Capital Medical University, Department of Radiology, Beijing Anzhen Hospital, Beijing (China); Wang, Yining; Jin, Zhengyu [Chinese Academy of Medical Sciences, Department of Radiology, Peking Union Medical College Hospital, Beijing (China); Zhang, Longjiang; Lu, Guangming [Nanjing University, Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing, Jiangsu (China)

    2013-07-15

    To investigate the feasibility of applying prospectively ECG-triggered sequential coronary CT angiography (CCTA) to patients with atrial fibrillation (AF) and evaluate the image quality and radiation dose compared with a retrospectively ECG-gated helical protocol. 100 patients with persistent AF were enrolled. Fifty patients were randomly assigned to a prospective protocol and the other patients to a retrospective protocol using a second-generation dual-source CT (DS-CT). Image quality was evaluated using a four-point grading scale (1 = excellent, 2 = good, 3 = moderate, 4 = poor) by two reviewers on a per-segment basis. The coronary artery segments were considered non-diagnostic with a quality score of 4. The radiation dose was evaluated. Diagnostic segment rate in the prospective group was 99.4 % (642/646 segments), while that in the retrospective group was 96.5 % (604/626 segments) (P < 0.001). Effective dose was 4.29 {+-} 1.86 and 11.95 {+-} 5.34 mSv for each of the two protocols (P < 0.001), which was a 64 % reduction in the radiation dose for prospective sequential imaging compared with retrospective helical imaging. In AF patients, prospectively ECG-triggered sequential CCTA is feasible using second-generation DS-CT and can decrease >60 % radiation exposure compared with retrospectively ECG-gated helical imaging while improving diagnostic image quality. (orig.)

  6. Nonenhanced ECG-gated quiescent-interval single-shot MRA (QISS-MRA) of the lower extremities: Comparison with contrast-enhanced MRA

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, J. [Department of Diagnostic and Interventional Radiology, University of Duesseldorf, Medical Faculty, Duesseldorf (Germany); Blondin, D., E-mail: blondin@med.uni-duesseldorf.de [Department of Diagnostic and Interventional Radiology, University of Duesseldorf, Medical Faculty, Duesseldorf (Germany); Schmitt, P. [Siemens AG, Healthcare Sector, Erlangen (Germany); Bi, X. [Siemens Healthcare, Chicago, IL (United States); Sansone, R. [Department of Cardiology, University of Duesseldorf, Medical Faculty, Duesseldorf (Germany); Wittsack, H.-J.; Kroepil, P.; Quentin, M.; Kuhlemann, J.; Miese, F. [Department of Diagnostic and Interventional Radiology, University of Duesseldorf, Medical Faculty, Duesseldorf (Germany); Heiss, C.; Kelm, M. [Department of Cardiology, University of Duesseldorf, Medical Faculty, Duesseldorf (Germany); Antoch, G.; Lanzman, R.S. [Department of Diagnostic and Interventional Radiology, University of Duesseldorf, Medical Faculty, Duesseldorf (Germany)

    2012-05-15

    Aim: To evaluate electrocardiogram (ECG)-gated quiescent-interval single-shot magnetic resonance angiography (QISS-MRA) for nonenhanced assessment of peripheral artery occlusive disease (PAOD) using contrast-enhanced MRA (CE-MRA) as the reference standard. Materials and methods: Twenty-seven patients (mean age 66.6 {+-} 10.8 years) with PAOD were included in the study. QISS-MRA and CE-MRA of the lower extremity were performed using a 1.5 T MR scanner. In each patient, subjective image quality and the degree of stenosis were evaluated on a four-point scale for 15 predefined arterial segments. Results: Twenty-five of the 27 patients were considered for analysis. Subjective image quality of QISS-MRA was significantly lower for the distal aorta, pelvic arteries, and femoral arteries as compared to CE-MRA (p < 0.01), while no significant difference was found for other vascular segments. The degree of stenosis was overestimated with QISS-MRA in 23 of 365 (6.3%) segments and underestimated in two of 365 (0.5%) segments. As compared to CE-MRA, QISS-MRA had a high sensitivity (98.6%), specificity (96%) as well as positive and negative predictive value (88.7 and 99.6%, respectively) for the detection of significant stenosis ({>=}50%). Conclusion: ECG-gated QISS-MRA is a promising imaging technique for reliable assessment of PAOD without the use of contrast material.

  7. Effect of physiological heart rate variability on quantitative T2 measurement with ECG-gated Fast Spin Echo (FSE) sequence and its retrospective correction.

    Science.gov (United States)

    de Roquefeuil, Marion; Vuissoz, Pierre-André; Escanyé, Jean-Marie; Felblinger, Jacques

    2013-11-01

    Quantitative T2 measurement is applied in cardiac Magnetic Resonance Imaging (MRI) for the diagnosis and follow-up of myocardial pathologies. Standard Electrocardiogram (ECG)-gated fast spin echo pulse sequences can be used clinically for T2 assessment, with multiple breath-holds. However, heart rate is subject to physiological variability, which causes repetition time variations and affects the recovery of longitudinal magnetization between TR periods. The bias caused by heart rate variability on quantitative T2 measurements is evaluated for fast spin echo pulse sequence. Its retrospective correction based on an effective TR is proposed. Heart rate variations during breath-holds are provided by the ECG recordings from healthy volunteers. T2 measurements were performed on a phantom with known T2 values, by synchronizing the sequence with the recorded ECG. Cardiac T2 measurements were performed twice on six volunteers. The impact of T1 on T2 is also studied. Maximum error in T2 is 26% for phantoms and 18% for myocardial measurement. It is reduced by the proposed compensation method to 20% for phantoms and 10% for in vivo measurements. Only approximate knowledge of T1 is needed for T2 correction. Heart rate variability may cause a bias in T2 measurement with ECG-gated FSE. It needs to be taken into account to avoid a misleading diagnosis from the measurements. © 2013.

  8. Axial-scanning low-coherence interferometer method for noncontact thickness measurement of biological samples.

    Science.gov (United States)

    Kim, Do-Hyun; Song, Chul-Gyu; Ilev, Ilko K; Kang, Jin U

    2011-02-20

    We investigated a high-precision optical method for measuring the thickness of biological samples regardless of their transparency. The method is based on the precise measurement of optical path length difference of the end surfaces of objects, using a dual-arm axial-scanning low-coherence interferometer. This removes any consideration of the shape, thickness, or transparency of testing objects when performing the measurement. Scanning the reference simplifies the measurement setup, resulting in unambiguous measurement. Using a 1310 nm wavelength superluminescent diode, with a 65 nm bandwidth, the measurement accuracy was as high as 11.6 μm. We tested the method by measuring the thickness of both transparent samples and nontransparent soft biological tissues.

  9. Axial-scanning low-coherence interferometer method for noncontact thickness measurement of biological samples

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do-Hyun; Song, Chul-Gyu; Ilev, Ilko K.; Kang, Jin U.

    2011-02-20

    We investigated a high-precision optical method for measuring the thickness of biological samples regardless of their transparency. The method is based on the precise measurement of optical path length difference of the end surfaces of objects, using a dual-arm axial-scanning low-coherence interferometer. This removes any consideration of the shape, thickness, or transparency of testing objects when performing the measurement. Scanning the reference simplifies the measurement setup, resulting in unambiguous measurement. Using a 1310 nm wavelength superluminescent diode, with a 65 nm bandwidth, the measurement accuracy was as high as 11.6 {mu}m. We tested the method by measuring the thickness of both transparent samples and nontransparent soft biological tissues.

  10. [Transpalpebral measurement of axial eye length. Use of contact B-scan sonography].

    Science.gov (United States)

    Martius, P; Tech, S; Stachs, O; Guthoff, R F

    2010-08-01

    In ophthalmology, it is very often necessary to determine the axial eye length. When standard measuring techniques fail, B-scan sonography may be used. However, coupling problems inhibit exact measurement. The aim of this study was to counter these problems. Correction values were created for the ultrasonic devices (1) Master-Vu (Sonomed), (2) CineScan (Quantel Medical), and (3) System-ABD (Innovative Imaging), including the position of the coupling layer of the hand pieces and the lid thickness. For evaluation of the method, the axial eye lengths of 35 eyes were measured transpalpebrally. These data were compared to those from the (4) IOL Master (Carl Zeiss Meditec). The usefulness of the developed method was shown by two patients. The correction values were (1) 3.0 mm, (2) 1.5 mm, and (3) 1.5 mm. The medial aberrations to (4) were (1) 0.4+/-0.5 mm, (2) 0.9+/-0.7 mm, and (3) 0.2+/-0.7 mm. The introduced method enables transpalpebral eye length measurement and is also applicable in cases of missing compliance or in eyes with an obfuscated optical medium.

  11. Axial Fan Blade Vibration Assessment under Inlet Cross-Flow Conditions Using Laser Scanning Vibrometry

    Directory of Open Access Journals (Sweden)

    Till Heinemann

    2017-08-01

    Full Text Available In thermal power plants equipped with air-cooled condensers (ACCs, axial cooling fans operate under the influence of ambient flow fields. Under inlet cross-flow conditions, the resultant asymmetric flow field is known to introduce additional harmonic forces to the fan blades. This effect has previously only been studied numerically or by using blade-mounted strain gauges. For this study, laser scanning vibrometry (LSV was used to assess fan blade vibration under inlet cross-flow conditions in an adapted fan test rig inside a wind tunnel test section. Two co-rotating laser beams scanned a low-pressure axial fan, resulting in spectral, phase-resolved surface vibration patterns of the fan blades. Two distinct operating points with flow coefficients of 0.17 and 0.28 were examined, with and without inlet cross-flow influence. While almost identical fan vibration patterns were found for both reference operating points, the overall blade vibration increased by 100% at the low fan flow rate as a result of cross-flow, and by 20% at the high fan flow rate. While numerically predicted natural frequency modes could be confirmed from experimental data as minor peaks in the vibration amplitude spectrum, they were not excited significantly by cross-flow. Instead, primarily higher rotation-rate harmonics were amplified; that is, a synchronous blade-tip flapping was strongly excited at the blade-pass frequency.

  12. Axial resolution and the value of interpolating scan in multislice positron computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Senda, M.; Yonekura, Y.; Tamaki, N.; Tanaka, Y.; Komori, M.; Minato, K.; Torizuka, K.

    1985-05-01

    The authors have calculated the aperture function of a positron computed tomograph (PCT) with computer simulation and evaluated both theoretically and experimentally the axial resolution of a multislice PCT, Positologica III, which has 7 slices at the interval of 16mm. The axial point spread function (PSF) was approximately a triangle at or near the center of the field and the sensitivity for the slice decreased significantly as the source moved away off the image plane. Accordingly there are low sensitivity areas between an in-plane and the adjacent cross-plane. In experiments using a myocardial phantom, a small myocardial defect of 1cm diameter could not be detected when dropped into the gap between slices, although the machine had sufficiently high resolution to deliniate it if it was on the image plane. When long-axis images of the ''myocardium'' were reconstructed three-dimensionally from the images obtained in single object position, the ''inferior wall'' dropped into the gap and disappeared. In clinical myocardial scan with N-13 labeled ammonia in a normal volunteer, a false positive defect appeared in the inferior wall. However, when the object is slided half the slice interval to perform the ''interpolating'' scan and the two sets of images were interlaced with each other, no artifacts appeared. These results have suggested that the invisible regions between slices may be clinically significant if the object is thin enough in z-axis. In order to fill up the gaps between slices, it is valuable to perform the interpolating scan.

  13. Prognostic significance of stress myocardial ECG-gated perfusion imaging in asymptomatic patients with diabetic chronic kidney disease on initiation of haemodialysis

    Energy Technology Data Exchange (ETDEWEB)

    Momose, Mitsuru; Kondo, Chisato; Kobayashi, Hideki; Kusakabe, Kiyoko [Tokyo Women' s Medical University, School of Medicine, Department of Radiology, Shinjuku-ku, Tokyo (Japan); Babazono, Tetsuya [Tokyo Women' s Medical University, School of Medicine, Diabetes Centre, Shinjuku-ku, Tokyo (Japan); Nakajima, Takatomo [Tokyo Women' s Medical University, School of Medicine, Department of Cardiology, Shinjuku-ku, Tokyo (Japan)

    2009-08-15

    Diabetic patients with chronic kidney disease (CKD) frequently develop cardiac events within several years of the initiation of haemodialysis. The present study assesses the prognostic significance of stress myocardial ECG-gated perfusion imaging (MPI) in patients with diabetic CKD requiring haemodialysis. Fifty-five asymptomatic patients with diabetic stage V CKD and no history of heart disease scheduled to start haemodialysis were enrolled in this study (56{+-}11 years old; 49 with type 2 diabetes mellitus). All patients underwent {sup 201}Tl stress ECG-gated MPI 1 month before or after the initiation of haemodialysis to assess myocardial involvement. We evaluated SPECT images using 17-segment defect scores graded on a 5-point scale, summed stress score (SSS) and summed difference scores (SDS). The patients were followed up for at least 2 years (42{+-}15 months) to determine coronary intervention (CI) and heart failure (HF) as soft events and acute myocardial infarction (AMI) and all causes of deaths as hard events. The frequencies of myocardial ischaemia, resting perfusion defects, low ejection fraction and left ventricular (LV) dilatation were 24,20,29 and 49%, respectively. Ten events (18%) developed during the follow-up period including four CI, one HF, one AMI and four sudden deaths. Multivariate Cox analysis selected SDS (p=0.0011) and haemoglobin A{sub 1c} (HbA{sub 1c}) (p=0.0076) as independent prognostic indicators for all events. Myocardial ischaemia, in addition to glycaemic control, is a strong prognostic marker for asymptomatic patients with diabetic CKD who are scheduled to start haemodialysis. Stress MPI is highly recommended for the management and therapeutic stratification of such patients. (orig.)

  14. The Image Quality and Radiation Dose of 100-kVp versus 120-kVp ECG-Gated 16-Slice CT Coronary Angiography

    Energy Technology Data Exchange (ETDEWEB)

    Park, Eun Ah; Lee, Whal; Kang, Jin Hwa; Yin, Yong Hu; Chung, Jin Wook; Park, Jae Hyung [Seoul National University Hospital, Seoul (Korea, Republic of)

    2009-06-15

    This study was conducted to assess the feasibility of performing 100-kVp electrocardiogram (ECG)-gated coronary CT angiography, as compared to 120-kVp ECG-gated coronary CT angiography. We retrospectively evaluated one hundred eighty five gender- and body mass index-matched 16-slice coronary CT sets of data, which were obtained using either 100 kVp and 620 effective mAs or 120 kVp and 500 effective mAs. The density measurements (image noise, vessel density, signal-tonoise ratio [SNR] and contrast-to-noise ratio [CNR]) and the estimated radiation dose were calculated. As a preference test, two image readers were independently asked to choose one image from each pair of images. The results of both protocols were compared using the paired t-test or the Wilcoxon signed rank test. The 100-kVp images showed significantly more noise and a significantly higher vessel density than did the 120-kVp images. There were no significant differences in the SNR and CNR. The estimated reduction of the radiation dose for the 100-kVp protocol was 24%; 7.8 {+-} 0.4 mSV for 100-kVp and 10.1 {+-} 1.0 mSV for 120-kVp (p < 0.001). The readers preferred the 100-kVp images for reading (reader 1, p = 0.01; reader 2, p = 0.06), with their preferences being stronger when the subject's body mass index was less than 25. Reducing the tube kilovoltage from 120 to 100 kVp allows a significant reduction of the radiation dose without a significant change in the SNR and the CNR.

  15. Prospective versus retrospective ECG gating for dual source CT of the coronary stent: Comparison of image quality, accuracy, and radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Lei, E-mail: zhaolei219@sohu.com [Beijing Anzhen Hospital of the Capital University of Medical Sciences (China); Zhang Zhaoqi; Fan Zhanming; Yang Lin; Du Jing [Beijing Anzhen Hospital of the Capital University of Medical Sciences (China)

    2011-03-15

    Objective: To compare image quality, diagnostic accuracy and radiation dose of prospective and retrospective electrocardiogram (ECG) gated dual source computed tomography (DSCT) for the evaluation of the coronary stent, using conventional coronary angiography (CA) as a standard reference. Design, setting and patients: Sixty patients (heart rates {<=}70 bpm) with previous stent implantation who were scheduled for CA were divided in two groups, receiving either prospective or retrospective ECG gated DSCT separately. Two reviewers scored coronary stent image quality and evaluated stent lumen. Results: There was no significant difference in image quality between the two groups. In the prospective group, there were 86.4% (51/59) stents with interpretable images, in the retrospective group, there were 87.5% (49/56) stents with interpretable images. Image quality was not influenced by age, body mass index or heart rate in either group, but heart rate variability had a weak impact on the image quality of the prospective group. Image noise was higher in the prospective group, but this difference reached statistical significance only by using a smooth kernel reconstruction. Per-stent based sensitivity, specificity, and positive and negative predictive value were 100%, 84.1%, 68.2%, and 100%, respectively, in the prospective CT angiography group and 94.4%, 86.8%, 77.3%, and 97.1%, respectively, in the retrospective CT angiography group. There was a significant difference in the effective radiation dose between the two groups, mean effective dose in the prospective and retrospective group was 2.2 {+-} 0.5 mSv (1.5-3.2 mSv) and 14.6 {+-} 3.3 mSv (10.0-20.4 mSv) (p < .001) respectively. Conclusions: Compared with retrospective CT angiography, prospective CT angiography has a similar performance in assessing coronary stent patency, but a lower effective dose in selected patients with regular heart rates {<=}70 bpm.

  16. Evaluation of biventricular ejection fraction with ECG-gated 16-slice CT: preliminary findings in acute pulmonary embolism in comparison with radionuclide ventriculography

    Energy Technology Data Exchange (ETDEWEB)

    Coche, Emmanuel; Goncette, Louis; Maldague, Baudouin [Universite Catholique de Louvain, Department of Medical Imaging, Cliniques Universitaires St-Luc, Brussels (Belgium); Vlassenbroek, Alain [Philips Medical Systems, Cleveland, OH (United States); Roelants, Veronique [Universite Catholique de Louvain, Department of Nuclear Medicine, Cliniques Universitaires St-Luc, Brussels (Belgium); D' Hoore, William [Catholic University of Louvain, Public Health, Brussels (Belgium); Verschuren, Franck [Universite Catholique de Louvain, Department of Emergency Medicine, Cliniques Universitaires St-Luc, Brussels (Belgium)

    2005-07-01

    This study aimed to assess the feasibility of cardiac global function evaluation during a whole-chest multi-slice CT (MSCT) acquisition in patients referred for suspicion of pulmonary embolism (PE), and to compare the results with planar equilibrium radionuclide ventriculography (ERNA). Ten consecutive haemodynamically stable patients (six female, four male; mean age 69.7 years; heart rate 65-99 bpm) with suspicion of PE underwent an MSCT and ERNA within a 6 h period. CT acquisition was performed after contrast medium injection by using 16 x 1.5 mm collimation and retrospective ECG gating. Left ventricular (LVEF) and right ventricular (RVEF) ejection fractions were calculated using dedicated three-dimensional software. Relationships between measurements obtained with MSCT and ERNA were assessed using linear regression analysis and reliability of MSCT was assessed with intra-class correlation coefficient. Bland-Altman analysis was performed to calculate limits of agreement between MSCT and ERNA. MSCT was performed successfully in ten patients with a mean acquisition time of 16.5{+-}2.8 s. Functional cardiac evaluation was possible on CT for all patients except for one due to poor opacification of right ventricle. Linear regression analysis showed a good correlation between MSCT and ERNA for the LVEF (R=0.91) and the RVEF (R=0.89) measurements. Intra-class correlation was superior for LVEF (0.92) than for the RVEF (0.68). Bland-Altman plots demonstrated that MSCT substantially overestimated the ERNA RVEF. Morphological CT data demonstrated PE in four of ten of patients and alternative diagnoses in five of ten patients. Our study reveals that MSCT with retrospective ECG gating may provide in one modality a morphological and a functional cardiopulmonary evaluation. Comparison with ERNA demonstrated a good correlation for both ventricular ejection fractions. (orig.)

  17. Evaluation of biventricular ejection fraction with ECG-gated 16-slice CT: preliminary findings in acute pulmonary embolism in comparison with radionuclide ventriculography.

    Science.gov (United States)

    Coche, Emmanuel; Vlassenbroek, Alain; Roelants, Véronique; D'Hoore, William; Verschuren, Franck; Goncette, Louis; Maldague, Baudouin

    2005-07-01

    This study aimed to assess the feasibility of cardiac global function evaluation during a whole-chest multi-slice CT (MSCT) acquisition in patients referred for suspicion of pulmonary embolism (PE), and to compare the results with planar equilibrium radionuclide ventriculography (ERNA). Ten consecutive haemodynamically stable patients (six female, four male; mean age 69.7 years; heart rate 65-99 bpm) with suspicion of PE underwent an MSCT and ERNA within a 6 h period. CT acquisition was performed after contrast medium injection by using 16x1.5 mm collimation and retrospective ECG gating. Left ventricular (LVEF) and right ventricular (RVEF) ejection fractions were calculated using dedicated three-dimensional software. Relationships between measurements obtained with MSCT and ERNA were assessed using linear regression analysis and reliability of MSCT was assessed with intra-class correlation coefficient. Bland-Altman analysis was performed to calculate limits of agreement between MSCT and ERNA. MSCT was performed successfully in ten patients with a mean acquisition time of 16.5+/-2.8 s. Functional cardiac evaluation was possible on CT for all patients except for one due to poor opacification of right ventricle. Linear regression analysis showed a good correlation between MSCT and ERNA for the LVEF (R=0.91) and the RVEF (R=0.89) measurements. Intra-class correlation was superior for LVEF (0.92) than for the RVEF (0.68). Bland-Altman plots demonstrated that MSCT substantially overestimated the ERNA RVEF. Morphological CT data demonstrated PE in four of ten of patients and alternative diagnoses in five of ten patients. Our study reveals that MSCT with retrospective ECG gating may provide in one modality a morphological and a functional cardiopulmonary evaluation. Comparison with ERNA demonstrated a good correlation for both ventricular ejection fractions.

  18. Burn-Up Determination by High Resolution Gamma Spectrometry: Axial and Diametral Scanning Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Forsyth, R.S.; Blackadder, W.H.; Ronqvist, N.

    1967-02-15

    In the gamma spectrometric determination of burn-up the use of a single fission product as a monitor of the specimen fission rate is subject to errors caused by activity saturation or, in certain cases, fission product migration. Results are presented of experiments in which all the resolvable gamma peaks in the fission product spectrum have been used to calculate the fission rate; these results form a pattern which reflect errors in the literature values of the gamma branching ratios, fission yields etc., and also represent a series of empirical correction factors. Axial and diametral scanning experiments on a long-irradiated low-enrichment fuel element are also described and demonstrate that it is possible to differentiate between fissions in U-235 and in Pu-239 respectively by means of the ratios of the Ru-106 activity to the activities of the other fission products.

  19. Enhanced Axial Resolution of Wide-Field Two-Photon Excitation Microscopy by Line Scanning Using a Digital Micromirror Device

    Directory of Open Access Journals (Sweden)

    Jong Kang Park

    2017-03-01

    Full Text Available Temporal focusing multiphoton microscopy is a technique for performing highly parallelized multiphoton microscopy while still maintaining depth discrimination. While the conventional wide-field configuration for temporal focusing suffers from sub-optimal axial resolution, line scanning temporal focusing, implemented here using a digital micromirror device (DMD, can provide substantial improvement. The DMD-based line scanning temporal focusing technique dynamically trades off the degree of parallelization, and hence imaging speed, for axial resolution, allowing performance parameters to be adapted to the experimental requirements. We demonstrate this new instrument in calibration specimens and in biological specimens, including a mouse kidney slice.

  20. Axial segmentation of lungs CT scan images using canny method and morphological operation

    Science.gov (United States)

    Noviana, Rina; Febriani, Rasal, Isram; Lubis, Eva Utari Cintamurni

    2017-08-01

    Segmentation is a very important topic in digital image process. It is found simply in varied fields of image analysis, particularly within the medical imaging field. Axial segmentation of lungs CT scan is beneficial in designation of abnormalities and surgery planning. It will do to ascertain every section within the lungs. The results of the segmentation are accustomed discover the presence of nodules. The method which utilized in this analysis are image cropping, image binarization, Canny edge detection and morphological operation. Image cropping is done so as to separate the lungs areas, that is the region of interest. Binarization method generates a binary image that has 2 values with grey level, that is black and white (ROI), from another space of lungs CT scan image. Canny method used for the edge detection. Morphological operation is applied to smoothing the lungs edge. The segmentation methodology shows an honest result. It obtains an awfully smooth edge. Moreover, the image background can also be removed in order to get the main focus, the lungs.

  1. Diagnostic performance of prospectively ECG triggered versus retrospectively ECG gated 64-slice computed tomography coronary angiography in a heterogeneous patient population

    Energy Technology Data Exchange (ETDEWEB)

    Lehmkuhl, Lukas, E-mail: lukas.lehmkuhl@med.uni-leipzig.de [University of Leipzig - Heart Center, Department of Diagnostic and Interventional Radiology, Struempellstrasse 39, D-04289 Leipzig (Germany); Herz, Franziska; Foldyna, Borek [University of Leipzig - Heart Center, Department of Diagnostic and Interventional Radiology, Struempellstrasse 39, D-04289 Leipzig (Germany); Nagel, Hans Dieter [Dr. HD Nagel - Science and Technology for Radiology, Buchholz (Germany); Grothoff, Matthias; Nitzsche, Stefan [University of Leipzig - Heart Center, Department of Diagnostic and Interventional Radiology, Struempellstrasse 39, D-04289 Leipzig (Germany); Thiele, Holger [University of Leipzig - Heart Center, Department for Cardiology (Germany); Mohr, Friedrich-Wilhelm [University of Leipzig - Heart Center, Department for Cardiovascular Surgery (Germany); Hindricks, Gerhard [University of Leipzig - Heart Center, Department for Cardiology (Germany); Gutberlet, Matthias [University of Leipzig - Heart Center, Department of Diagnostic and Interventional Radiology, Struempellstrasse 39, D-04289 Leipzig (Germany)

    2011-11-15

    Objective: To compare diagnostic performance and applicability of prospectively versus retrospectively gated 64-slice computed tomography coronary angiography (pro-CTCA vs. retro-CTCA) in a heterogeneous patient population compared to invasive coronary angiography. Methods: 77 patients referred to an ECG-gated-CT of the chest were retrospectively included. Pro-CTCA was applied, whenever possible, alternatively retro-CTCA was performed. All coronary artery segments {>=}1.5 mm were analysed and image quality was assessed. Results: In 39 patients retro-CTCA and in 38 patients pro-CTCA was applied, mean heart rate (HR) was 69.5 {+-} 9.1 min{sup -1} and 62.8 {+-} 5.9, respectively. For a stenosis {>=}50% segment-based (patient-based) analysis revealed a sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of 97%, 98%, 71%, 100% (91%, 82%, 67%, 96%) using retro-CTCA and 94%, 97%, 75%, 99% (93%, 96%, 93%, 96%) using pro-CTCA. Sensitivity and NPV increased in the pro-CTCA group in patients with a HR < 65. Vessel-based analysis showed lower diagnostic performance for the right coronary artery (RCA) using pro-CTCA, which increased when HR < 65. Image quality did not differ significantly in both groups. Conclusions: Prospectively triggered CTCA in a heterogeneous patient group has a very high diagnostic accuracy and image quality, when used in HR {<=} 65. A low HR is of special importance for the evaluation of the RCA.

  2. Assessment of automatic quantification of myocardial perfusion and left ventricular function derived from ECG gated myocardial SPECT with {sup 99m}Tc-tetrofosmin in ischemic heart disease

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Mitsunori; Habara, Hirokazu; Tatsuno, Hironari; Fukuda, Hiroshi; Hamada, Noriko; Kazatani, Yukio [Ehime Prefectural Central Hospital (Japan)

    1999-09-01

    Non-invasive assessment of ischemic heart disease (IHD) requires information of both myocardial perfusion and left ventricular (LV) function. Recently, automatic quantification of ECG-gated myocardial scintigraphy with {sup 99m}Tc-tetrofosmin (QGS) can provide both of them. QGS, coronary angiograms (CAG) and left venticulograms (LVG) were performed in 83 patients with severe IHD in same period. Significant stenosis of coronary artery in CAG were assessed by QGS. The sensitivity, specificity and accuracy of significant stenosis by QGS was excellent (85%, 93% and 88%). The LV end-distolic and end-systolic volumes (EDV and ESV), LV ejection fraction (EF) and regional LV wall motion determined by QGS were compared to LVG. There was a good correlation between the values obtained from QGS and LVG (EDV: r=0.86, ESV: r=0.94, EF: r=0.84, p<0.0001), but QGS tended to underestimate EDV and EF. High complete agreement of regional LV wall motion was gained with 427 (74.0%) out of total 581 segments. In conclusion, QGS data was considered to be useful for assessment of determine significant stenosis and LV function in severe IHD. (author)

  3. Safety and efficacy of a drug regimen to control heart rate during 64-slice ECG-gated coronary CTA in children

    Energy Technology Data Exchange (ETDEWEB)

    Rigsby, Cynthia K.; Nicholas, Angela C. [Children' s Memorial Hospital, Department of Medical Imaging, 2300 Children' s Plaza, Box 9, Chicago, IL (United States); deFreitas, R.A. [Children' s Memorial Hospital, Department of Pediatrics, Chicago, IL (United States); Leidecker, Christianne [Siemens Medical Solutions, Malvern, PA (United States); Johanek, Andrew J. [Children' s Memorial Hospital, Department of Medical Imaging, 2300 Children' s Plaza, Box 9, Chicago, IL (United States); Provena St. Joseph Medical Center, Department of Radiology, Joliet, IL (United States); Anley, Peter [Children' s Memorial Hospital, Pharmacy Department, Chicago (United States); Wang, Deli [Children' s Memorial Hospital, Biostatistical Research Department, Chicago, IL (United States); Uejima, Tetsu [Children' s Memorial Hospital, Department of Anesthesiology, Chicago, IL (United States)

    2010-12-15

    The adult practice for ECG-gated single-source 64-slice coronary CTA (CCTA) includes administering beta-blockers to reduce heart rate. There are limited data on this process in children. To evaluate the safety and efficacy of a drug regimen to decrease heart rate before performing CCTA in children. IV remifentanil and esmolol infusion were chosen to decrease heart rate in 41 children (mean age 6.5 years) while they were under general anesthesia (GA) for CCTA. Drug doses, changes in heart rate and procedural complications were recorded. CCTA image quality was graded on a scale of 1 to 5. The relationships between image quality and heart rate and image quality and age were evaluated. Patient effective radiation doses were calculated. Heart rates were lowered utilizing esmolol (4 children), remifentanil (2 children) or both (35 children); 26 children received nitroglycerin for coronary vasodilation. The mean decrease in heart rate was 26%. There were no major complications. The average image-quality score was 4.4. Higher heart rates were associated with worse image quality (r = 0.67, P < 0.0001). Older age was associated with better image quality (r = 0.66, P < 0.0001). Effective radiation doses were 0.7 to 7.0 mSv. Heart rate reduction for pediatric CCTA can be safely and effectively achieved while yielding high-quality images. (orig.)

  4. Quantitative analysis of arterial flow properties for detection of non-calcified plaques in ECG-gated coronary CT angiography

    Science.gov (United States)

    Wei, Jun; Zhou, Chuan; Chan, Heang-Ping; Chughtai, Aamer; Agarwal, Prachi; Kuriakose, Jean; Hadjiiski, Lubomir; Patel, Smita; Kazerooni, Ella

    2015-03-01

    We are developing a computer-aided detection system to assist radiologists in detection of non-calcified plaques (NCPs) in coronary CT angiograms (cCTA). In this study, we performed quantitative analysis of arterial flow properties in each vessel branch and extracted flow information to differentiate the presence and absence of stenosis in a vessel segment. Under rest conditions, blood flow in a single vessel branch was assumed to follow Poiseuille's law. For a uniform pressure distribution, two quantitative flow features, the normalized arterial compliance per unit length (Cu) and the normalized volumetric flow (Q) along the vessel centerline, were calculated based on the parabolic Poiseuille solution. The flow features were evaluated for a two-class classification task to differentiate NCP candidates obtained by prescreening as true NCPs and false positives (FPs) in cCTA. For evaluation, a data set of 83 cCTA scans was retrospectively collected from 83 patient files with IRB approval. A total of 118 NCPs were identified by experienced cardiothoracic radiologists. The correlation between the two flow features was 0.32. The discriminatory ability of the flow features evaluated as the area under the ROC curve (AUC) was 0.65 for Cu and 0.63 for Q in comparison with AUCs of 0.56-0.69 from our previous luminal features. With stepwise LDA feature selection, volumetric flow (Q) was selected in addition to three other luminal features. With FROC analysis, the test results indicated a reduction of the FP rates to 3.14, 1.98, and 1.32 FPs/scan at sensitivities of 90%, 80%, and 70%, respectively. The study indicated that quantitative blood flow analysis has the potential to provide useful features for the detection of NCPs in cCTA.

  5. Step-and-shoot prospectively ECG-gated versus retrospectively ECG-gated with tube current modulation coronary CT angiography using the 128-slice MDCT: comparison of image quality and radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Dong Wook (Dept. of Family Medicine, Medial Research Institute, Pusan National Univ. Yangsan Hospital, School of Medicine, Gyeongsangnam-do, (Korea, Republic of)); Choo, Ki Seok; Baik, Seung Kug; Kim, Yong Woo; Jeon, Ung Bae (Dept. of Radiology, Medial Research Institute, Pusan National Univ. Yangsan Hospital, School of Medicine, Gyeongsangnam-do, (Korea, Republic of)), email: kschoo0618@naver.com; Kim, Jeong Soo (Dept. of Cardiology, Medial Research Institute, Pusan National Univ. Yangsan Hospital, School of Medicine, Gyeongsangnam-do (Korea, Republic of)); Lim, Soo Jin (Dept. of Cardiology, Kim Hae Joongang Hospital, Gyeongsangnam-do (Korea, Republic of))

    2011-02-15

    Background: Little is known regarding image quality and the required radiation dose for step-and-shoot and retrospective coronary computed tomography angiography (CCTA) with tube current modulation (TCM) in 128-slice multidetector CT (MDCT) coronary angiography. Purpose: To compare image quality and radiation dose in patients who underwent 128-slice MDCT by the step-and- shoot method with those in patients who underwent 128-slice MDCT with retrospective CCTA with TCM. Material and Methods: CCTA obtained with 128-slice MDCT was retrospectively evaluated in 160 patients. Two independent reviewers separately scored the subjective image quality of the coronary artery segments (1, excellent; 4, poor) for step-and-shoot (68, mean heart rate [HR]: 59.3+-6.8) and retrospective CCTA with TCM (77, mean HR: 59.1+-9.8). Interobserver variability was calculated. Effective radiation doses of both scan techniques were calculated with dose-length product. Results: There was good agreement for quality scores of coronary artery segment images between the independent reviewers (k=0.72). The number of coronary artery segments that could not be evaluated was 2.85% (27 of 947) in the step-and-shoot and 1.87% (20 of 1071) in retrospective CCTA with TCM. Image quality scores were not significantly different (P>.05). Mean patient radiation dose was 63% lower for step-and-shoot (1.94+-0.70 mSv) than for retrospective CCTA with TCM (4.51+-1.18 mSv) (P<0.0001). For patients who underwent step-and-shoot or retrospective CCTA with TCM, an average HR of 63.5 beats per minute was identified as the threshold for the prediction of non-diagnostic image quality for both protocols. There were no significant differences in the image quality of both methods between obese (body mass index [BMI>=25) and non-obese patients (BMI<25), but radiation doses were higher in the obesity group than in the non-obesity group for both methods. Conclusion: Both step-and-shoot and retrospective CCTA with TCM using 128

  6. Evaluation of regional work from ECG-gated SPECT images through solution of equations of continuity for fluids-mechanical cardiac work calculated using thin wall model.

    Science.gov (United States)

    Maeda, Hisatoshi

    2012-03-01

    Regional contraction work (RCW) of left ventricle (LV) was evaluated from cardiac perfusion images of ECG-gated single photon emission computed tomography (ECG-SPECT). The mechanical work was computed as a product of force and displaced distance. Force was determined from Laplace's law under a rectangle pressure. Deformation of wireframe representing LV was calculated from equations of continuity for two-dimensional fluids. Experiments were performed with homemade life-sized cardiac models. Total contraction work (TCW) and stroke work (SW) were 524.0 ± 166.1 mJ/beat and 709.8 ± 169.5 mJ/beat, respectively, in normal subjects (n = 23). Moderate correlation was seen between TCW and SW (y = -43.4 + 0.779 x, r = 0.815). The regional contraction amplitude (RCA), synchronous contraction index and RCW were 35.4 ± 3.5%, 95.4 ± 3.1% and 5.58 ± 0.97 mJ cm(-2)/beat in normal subjects, whereas those in patients with decreased ejection raction (EF) ≤ 30% (n = 6) were 19.6 ± 7.7%, 64.4 ± 32.2% and 2.58 ± 0.82 mJ cm(-2)/beat (p < 0.0001, Student's t-test). There was a poor correlation between RCW and RCA (y = 1.648 ± 0.116 x, r = 0.501) in normal subjects, suggesting that it might not be suitable to use RCA as an alternative to evaluate RCW.

  7. High-resolution 3D non-contrast-enhanced, ECG-gated, multi-step MR angiography of the lower extremities: Comparison with contrast-enhanced MR angiography

    Energy Technology Data Exchange (ETDEWEB)

    Mohrs, Oliver K. [University of Heidelberg, Department of Diagnostic and Interventional Radiology, Heidelberg (Germany); Darmstadt Radiology, Department of Cardiovascular Imaging at Alice-Hospital, Darmstadt (Germany); Petersen, Steffen E. [The London Chest Hospital, Centre for Advanced Cardiovascular Imaging, William Harvey Research Institute, Barts and The London NIHR Biomedical Research Unit, London (United Kingdom); Heidt, Martin C. [Cardiovascular Center Darmstadt, Darmstadt (Germany); Schulze, Thomas; Schmitt, Peter [Siemens AG, Healthcare Sector, MR Application and Workflow Development, Erlangen (Germany); Bergemann, Sabine [Darmstadt Radiology, Department of Cardiovascular Imaging at Alice-Hospital, Darmstadt (Germany); Kauczor, Hans-Ulrich [University of Heidelberg, Department of Diagnostic and Interventional Radiology, Heidelberg (Germany)

    2011-02-15

    To determine the diagnostic value of non-contrast-enhanced, 3D-high-resolution, ECG-gated, multi-step MR angiography (non-ceMRA) of the lower extremities using a modified turbo-spin-echo technique in comparison to 1.0-molar contrast-enhanced MR angiography (ceMRA) in patients with suspected peripheral vascular disease (PVD). Fifty consecutive patients underwent non-ceMRA before ceMRA within the same session. We assessed examination time, image quality, localisation and severity of stenosis. Examination time was shorter for ceMRA (12 {+-} 4 min) compared with non-ceMRA (28 {+-} 6 min, p < 0.001). The image quality of the aorta-iliac, femoral and combined popliteal and lower leg arteries was inferior for non-ceMRA (2.8 {+-} 0.8/3.3 {+-} 0.8/3.3 {+-} 0.9) versus ceMRA (4.7 {+-} 0.8/4.8 {+-} 0.6/4.8 {+-} 0.7) on a 5-point scale with 5 for maximum quality (p < 0.01). CeMRA offered more assessable data sets than non-ceMRA (98% vs. 90%). For detecting stenosis >50% or occlusions of pelvic and femoral arteries using non-ceMRA the sensitivity, specificity, positive and negative predictive values were 94%, 86%, 67% and 98% and for popliteal and lower leg arteries 93%, 87%, 69% and 98%, respectively. We demonstrated that 3D non-ceMRA represents a very promising technique in patients with lower extremities PVD and could be used as an alternative if gadolinium-based contrast agents cannot be administered. (orig.)

  8. Ascending aorta measurements as assessed by ECG-gated multi-detector computed tomography: a pilot study to establish normative values for transcatheter therapies

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Tri-Linh C.; Rizzo, Elena [University Hospital Lausanne (CHUV), Department of Radiology, Lausanne (Switzerland); Huber, Christoph H.; Segesser, Ludwig K. von [University Hospital Lausanne (CHUV), Department of Cardiovascular Surgery, Lausanne (Switzerland); Dehmeshki, Jashmid [Kingston University, Digital Imaging Research Centre, Faculty of Computing, Information Systems and Mathematics, London (United Kingdom); Qanadli, Salah D. [University Hospital Lausanne (CHUV), Department of Radiology, Lausanne (Switzerland)]|[BH-07, Centre Hospitalier Universitaire Vaudois, Service de Radiodiagnostic et de Radiologie interventionnelle, Lausanne (Switzerland)

    2009-03-15

    The aim of this study was to provide an insight into normative values of the ascending aorta in regards to novel endovascular procedures using ECG-gated multi-detector CT angiography. Seventy-seven adult patients without ascending aortic abnormalities were evaluated. Measurements at relevant levels of the aortic root and ascending aorta were obtained. Diameter variations of the ascending aorta during cardiac cycle were also considered. Mean diameters (mm) were as follows: LV outflow tract 20.3{+-}3.4, coronary sinus 34.2{+-}4.1, sino-tubular junction 29.7{+-}3.4 and mid ascending aorta 32.7{+-}3.8 with coefficients of variation (CV) ranging from 12 to 17%. Mean distances (mm) were: from the plane passing through the proximal insertions of the aortic valve cusps to the right brachio-cephalic artery (BCA) 92.6{+-}11.8, from the plane passing through the proximal insertions of the aortic valve cusps to the proximal coronary ostium 12.1{+-}3.7, and between both coronary ostia 7.2{+-}3.1, minimal arc of the ascending aorta from left coronary ostium to right BCA 52.9{+-}9.5, and the fibrous continuity between the aortic valve and the anterior leaflet of the mitral valve 14.6{+-}3.3, CV 13-43%. Mean aortic valve area was 582.0{+-}131.9 mm{sup 2}. The variation of the antero-posterior and transverse diameters of the ascending aorta during the cardiac cycle were 8.4% and 7.3%, respectively. Results showed large inter-individual variations in diameters and distances but with limited intra-individual variations during the cardiac cycle. A personalized approach for planning endovascular devices must be considered. (orig.)

  9. Reliability analysis of visual ranking of coronary artery calcification on low-dose CT of the thorax for lung cancer screening: comparison with ECG-gated calcium scoring CT.

    Science.gov (United States)

    Kim, Yoon Kyung; Sung, Yon Mi; Cho, So Hyun; Park, Young Nam; Choi, Hye-Young

    2014-12-01

    Coronary artery calcification (CAC) is frequently detected on low-dose CT (LDCT) of the thorax. Concurrent assessment of CAC and lung cancer screening using LDCT is beneficial in terms of cost and radiation dose reduction. The aim of our study was to evaluate the reliability of visual ranking of positive CAC on LDCT compared to Agatston score (AS) on electrocardiogram (ECG)-gated calcium scoring CT. We studied 576 patients who were consecutively registered for health screening and undergoing both LDCT and ECG-gated calcium scoring CT. We excluded subjects with an AS of zero. The final study cohort included 117 patients with CAC (97 men; mean age, 53.4 ± 8.5). AS was used as the gold standard (mean score 166.0; range 0.4-3,719.3). Two board-certified radiologists and two radiology residents participated in an observer performance study. Visual ranking of CAC was performed according to four categories (1-10, 11-100, 101-400, and 401 or higher) for coronary artery disease risk stratification. Weighted kappa statistics were used to measure the degree of reliability on visual ranking of CAC on LDCT. The degree of reliability on visual ranking of CAC on LDCT compared to ECG-gated calcium scoring CT was excellent for board-certified radiologists and good for radiology residents. A high degree of association was observed with 71.6% of visual rankings in the same category as the Agatston category and 98.9% varying by no more than one category. Visual ranking of positive CAC on LDCT is reliable for predicting AS rank categorization.

  10. Axial-Stereo 3-D Optical Metrology for Inner Profile of Pipes Using a Scanning Laser Endoscope.

    Science.gov (United States)

    Gong, Yuanzheng; Johnston, Richard S; Melville, C David; Seibel, Eric J

    As the rapid progress in the development of optoelectronic components and computational power, 3D optical metrology becomes more and more popular in manufacturing and quality control due to its flexibility and high speed. However, most of the optical metrology methods are limited to external surfaces. This paper proposed a new approach to measure tiny internal 3D surfaces with a scanning fiber endoscope and axial-stereo vision algorithm. A dense, accurate point cloud of internally machined threads was generated to compare with its corresponding X-ray 3D data as ground truth, and the quantification was analyzed by Iterative Closest Points algorithm.

  11. Meta-analysis: diagnostic accuracy of coronary CT angiography with prospective ECG gating based on step-and-shoot, Flash and volume modes for detection of coronary artery disease

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Linfeng; Zhou, Tao; Zhang, Ruijie; Peng, Zhaohui; Ding, Juan; Wang, Sen; Li, Min; Sun, Gang [Jinan Military General Hospital, Department of Medical Imaging, Jinan, Shandong Province (China); Xu, Lin [Jinan Military General Hospital, Department of Medical Cardiology, Jinan, Shandong Province (China)

    2014-10-15

    To investigate the diagnostic performance of coronary computed tomographic angiography (CCTA) with prospective electrocardiograph (ECG) gating based on step-and-shoot (SAS), Flash and volume imaging modes. We searched the electronic databases PubMed for all published studies regarding CCTA. We used an exact binomial rendition of the bivariate mixed-effects regression model developed for synthesis of diagnostic data. A total of 21,852 segments, 4,851 vessels and 1,375 patients were identified using database searches. Patient-level pooled sensitivity was 0.99 (95 % confidence interval [CI], 0.98-1.00); specificity was 0.88 (CI, 0.85-0.91). The results showed that the sensitivity and specificity for detection of significant stenosis did not differ in the three protocols (P = 0.24). No heterogeneity was found at the patient level for sensitivity (Q = 26.23; P = 0.12; I {sup 2} = 27.56 % [CI, 0.00-67.02 %]) and specificity (Q = 19.54; P = 0.42; I {sup 2} = 2.78 % [CI, 0.00-66.26 %]). CCTA with prospective ECG gating has similar high diagnostic value to rule out CAD in all three presented modes. (orig.)

  12. False negative bone scans in pediatric sepsis of the axial skeleton

    Energy Technology Data Exchange (ETDEWEB)

    Perloff, K.G.; Glancy, G.L.; Perloff, J.J.

    1988-12-01

    The early diagnosis of disk space infections and sacroiliitis in children can be difficult because of protean presenting symptoms, nonspecific laboratory studies, and normal plain films. Technetium phosphate scintigraphy has been reported as a diagnostic method with an accuracy of up to 100% in some series. In this case report we present two patients with negative technetium bone scans in the face of active infection, illustrating the need to pursue the diagnosis using other modalities.

  13. Is It Possible to Predict Heart Rate and Range during Enhanced Cardiac CT Scan from Previous Non-enhanced Cardiac CT?

    OpenAIRE

    Horiguchi, Jun; Yamamoto, Hideya; Arie, Ryuichi; Kiguchi, Masao; Fujioka, Chikako; Ohtaki, Megu; Kihara, Yasuki; Awai, Kazuo

    2010-01-01

    The effect of heart rate and variation during cardiac computed tomography (CT) on the examination quality. The purpose of this study is to investigate whether it is possible to predict heart rate and range during enhanced cardiac computed CT scan from previous non-enhanced cardiac CT scan. Electrocardiograph (ECG) files from 112 patients on three types of cardiac 64-slice CT (non-enhanced, prospective ECG-triggered and retrospective ECG-gated enhanced scans) were recorded. The mean heart rate...

  14. 双源CT非心率控制自适应前瞻性心电门控序列扫描冠状动脉成像%CT coronary angiography without heart rate control with adaptive cardio sequence prospective ECG-gated using the second generation dual-source CT

    Institute of Scientific and Technical Information of China (English)

    王小琴; 钱农; 潘昌杰; 薛跃君; 王涛; 靳激扬

    2012-01-01

    Objective To explore the feasibility of improving image quality of low dose scanning using adaptive cardio sequence prospective ECG-gated without heart rate control by the second generation dual-source CT coronary angiography (CTCA). Methods Ninety-four consecutive patients were collected prospectively and underwent prospective ECG-gated a-daptive cardio sequence dual-source CTCA without heart rate control. Two experienced radiologists double-blindly assessed image quality of 15 segments of coronary arteries with five-score scale. Images with no less than 3 scores were usable for diagnosis. Correlation between image quality and heart rate, as well as with heart rate variability were analyzed. The intra-observer agreement for image quality was assessed. CT dose index of volume (CTDIvol) and effective dose (ED) were measured. Results The mean heart rate during scanning was (87. 24 13. 76) beats percent minute in all 94 patients. Totally 1410 segments of coronary arteries were included, and images useful for diagnosis (≥3 scores) were obtained in 1334 segments (94. 61%) of the coronary artery segments, while 76 segments (5. 39%) had non-assessable image quality. The mean image quality score for the whole coronary tree was 4. 25 0. 93. No correlation was observed between the mean heart rate (r= 0. 17, P = 0. 11) or heart rate variability (r=0. 10, P = 0. 32) and image quality. The Kappa value between two radiologists was 0.90 on image quality (P<0.001). CTDIvol and ED was (11.84+ 1.76)mGy and (2. 19 + 0. 45)mSv, respectively. Conclusion Using prospective ECG-gated adaptive cardio sequence, assessable image quality of coronary artery can be acquired with dual-source CT without heart rate control, and radiation dose can be obviously reduced.%目的 探讨双源CT非心率控制低剂量自适应前瞻性心电门控序列扫描冠状动脉成像的可行性.方法 前瞻性收集94例患者进行双源CT非心率控制自适应前瞻性心电门控序列扫

  15. ECG门控自动毫安技术在MSCT冠状动脉成像中的应用价值%The Application of ECG-gated Automatic mA Modulation Technique in the MSCT Cardiac Imaging

    Institute of Scientific and Technical Information of China (English)

    徐同江; 刘建新; 李坚

    2011-01-01

    目的:研究总结ECG门控自动毫安调制技术在MSCT冠状动脉成像中的应用价值,探讨心脏CT低剂量技术的初步经验和方法.方法:患者60例,其中30例随机使用固定毫安扫描,另30例使用ECG门控自动毫安调制技术扫描.以64排螺旋CT行冠状动脉成像,扫描前进行心率控制措施,使用后门控数据采集、容积再现(VR)、最大密度投影(MIP)、曲面重建(CPR);以MIP图像评价冠状动脉管腔;以VR图像5级记分法评价图像质量.结果:60例患者均成功获得冠状动脉影像.自动毫安组较固定毫安组平均剂量降低10.46%,而图像质量两组一致,无统计学差异.ECG门控自动毫安技术在保证图像质量的前提下能有效降低患者平均辐射剂量.结论:ECG门控自动毫安技术能有效降低患者射线剂量,只要准备措施有效及方法得当,就能够用低剂量完成64排MSCT冠状动脉检查,并可获得较满意的效果.%Objective: To research and summarize the application value of the ECG-gated automatic mA modulation technique in the cardiac visualization, and to investigate the initial experience and methods of the low dose using the process of 64-MSCT cardiac imaging. Methods: Sixty patients devided into two groups randomly,thirty patients who underwent the examination of MSCT cardiac imaging with fixed-ma, the other patients with ECG-gated automatic-ma technique. To control heart rate (HR) before examination, and underwent the post-processing with volume rendering (VR), maximum intensity projection (MIP), multiplanar reconstruction (MPR). Evaluated the cardiac vessel with the MIP imaging, and recorded the quality of imaging using the 5 grades.Results: Acquired cardiac imaging of all patients successfiully. Compared to the group of the using fixed-ma, the group of using ECG automatic-ma reduced average dosage 10.46%, and two groups had identical imaging quality.There was not significant difference between them. Conclusion: With the

  16. Diagnostic Sensitivity of Multidetector-Row Spiral Computed Tomography Angiography in the Evaluation of Type-II Endoleaks and their Source: Comparison between Axial Scans and Reformatting Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Saba, L.; Pascalis, L.; Montisci, R.; Sanfilippo, R.; Mallarini, G. (Depts. of Radiology and Vascular Surgery, Azienda Ospedaliero-Universitaria di Cagliari, Polo di Monserrato, Monserrato, Cagliari (Italy))

    2008-07-15

    Background: After endovascular stent-graft placement, several complications may occur. Retrograde filling of the aneurysm (type-II endoleak) is the most common. Purpose: To evaluate the accuracy, image quality, and interobserver agreement of multidetector-row spiral computed tomography angiography (MDCTA) in the diagnosis of type-II endoleak, by using various types of reformatting techniques in comparison to regular axial images. Material and Methods: Twenty-four patients who had had endovascular repair of an infrarenal abdominal aortic aneurysm with stent graft were retrospectively studied. In 12 of 24 patients, a type-II endoleak was found. CT scans were obtained after intravenous administration of 130 ml of nonionic contrast material using a 4-6-ml/s flow rate. All patients were investigated with axial scans, multiplanar reconstruction (MPR), maximum intensity projection (MIP), shaded-surface display (SSD), and volume-rendering (VR) techniques. For each patient and for each reconstruction method, the image quality of the scans was scored as 0 for bad quality, 1 for poor quality, 2 for good quality, and 3 for excellent quality images. Two radiologists reviewed the CT images independently. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each reconstruction method, with the axial images as the reference method. Interobserver agreement and kappa value were also recorded. Results: MPR showed the highest sensitivity (83% and 67% for observers 1 and 2, respectively), PPV (91% and 80% for observers 1 and 2, respectively), and NPV (85% and 71% for observers 1 and 2, respectively), whereas VR showed the highest specificity (92% for both observer 1 and 2). Conclusion: Reformatting techniques provide good-quality images; nevertheless, their efficacy in the study of type-II endoleak was found to be suboptimal in comparison to regular axial images. The MPR technique is probably the best choice in conjunction

  17. Magnetic resonance angiography (MRA) of the calf station at 3.0 T: intraindividual comparison of non-enhanced ECG-gated flow-dependent MRA, continuous table movement MRA and time-resolved MRA

    Energy Technology Data Exchange (ETDEWEB)

    Haneder, Stefan; Attenberger, Ulrike I.; Riffel, Philipp; Henzler, Thomas; Schoenberg, Stefan O.; Michaely, Henrik J. [University Medical Center Mannheim, Medical Faculty Mannheim-University of Heidelberg, Institute of Clinical Radiology and Nuclear Medicine, Mannheim (Germany)

    2011-07-15

    To compare 3D non-enhanced ECG-gated inflow-dependent MRA (NE-MRA) vs. continuous table movement (CTM) MR-angiography and time-resolved TWIST-MRA in the calf station at 3.0 T in a clinical patient collective. 36 patients (27 male/9 female, 66.1 {+-} 14.4 years) with PAOD (stage II-IV) underwent during a single MRI: NE-MRA, contrast-enhanced CTM-MRA and TWIST-MRA with a single dose of a gadolinium-based contrast agent. The image quality (IQ) and the degree of stenoses were rated on a four-point scale. Positive (PPV) and negative predictive values (NPV), sensitivity (SS) and specificity (SP) for stenoses detection were calculated for NE-MRA vs. CTM-MRA and vs. TWIST-MRA. Values were obtained for overall graduation of wall changes and for severe stenoses (>70%). With NE-MRA 122/288 segments were not assessable. Compared with CTM-MRA and TWIST-MRA the IQ was significantly inferior (p < 0.0001 to p = 0.0426). CTM-MRA/TWIST-MRA detected stenoses in 44.9%/46.1% of the segments, NE-MRA in 53.5%. SS/NPV of the NE-MRA ranged from 97.8 to 100%. The SP and PPV ranged from 72.7 to 85.5% and 66.7 to 78.2%. Contrast-enhanced MRA techniques are superior to NE-MRA regarding IQ and correct identification of stenoses. If technically successful, NE-MRA is characterised by high NPV and overestimation of the degree of stenoses. (orig.)

  18. 3D non-contrast-enhanced ECG-gated MR angiography of the lower extremities with dual-source radiofrequency transmission at 3.0 T: Intraindividual comparison with contrast-enhanced MR angiography in PAOD patients.

    Science.gov (United States)

    Rasper, Michael; Wildgruber, Moritz; Settles, Marcus; Eckstein, Hans-Henning; Zimmermann, Alexander; Reeps, Christian; Rummeny, Ernst J; Huber, Armin M

    2016-09-01

    To compare prospectively image quality and diagnostic confidence of flow-sensitive 3D turbo spin echo (TSE)-based non-contrast-enhanced MR angiography (NE-MRA) at 3.0 T using dual-source radiofrequency (RF) transmission with contrast-enhanced MRA (CE-MRA) in patients with peripheral arterial occlusive disease (PAOD). After consent was obtained, 35 patients (mean age 69.1 ± 10.6 years) with PAOD stage II-IV underwent NE-MRA followed by CE-MRA. Signal-to-noise ratio and contrast-to-noise ratio were calculated. Subjective image quality was independently assessed by two radiologists and stenosis scoring was performed in 875 arterial segments. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for stenosis classification were calculated using CE-MRA as a reference method. Diagnostic agreement with CE-MRA was evaluated with Cohen's kappa statistics. NE-MRA provided high objective and subjective image quality at all levels of the arterial tree. Sensitivity and specificity for the detection of relevant stenosis was 91 % and 89 %, respectively; the NPV was 96 % and the PPV 78 %. There was good concordance between CE-MRA and NE-MRA in stenosis scoring. 3D electrocardiography (ECG)-gated TSE NE-MRA with patient-adaptive dual-source RF transmission at 3.0 T is a promising alternative for PAOD patients with contraindications for gadolinium-based contrast agents. It offers high sensitivity and NPV values in the detection of clinically relevant arterial stenosis. • Flow-sensitive TSE NE-MRA is a promising technique for PAOD evaluation. • Diagnostic accuracy is comparable to contrast-enhanced MRA. • NE-MRA eliminates the risk of NSF in patients with renal insufficiency. • Costs arising from the use of contrast agents can be avoided.

  19. The amount of viable and dyssynchronous myocardium is associated with response to cardiac resynchronization therapy: initial clinical results using multiparametric ECG-gated [{sup 18}F]FDG PET

    Energy Technology Data Exchange (ETDEWEB)

    Lehner, Sebastian; Uebleis, Christopher; Haug, Alexander; Bartenstein, Peter [University of Munich, Department of Nuclear Medicine, Munich (Germany); Schuessler, Franziska; Kaeaeb, Stefan; Estner, Heidi [University of Munich, Medical Department I, Munich (Germany); Van Kriekinge, Serge D.; Germano, Guido [UCLA, Cedars-Sinai Medical Center, Los Angeles and David Geffen School of Medicine, Los Angeles, CA (United States); Hacker, Marcus [Medical University of Vienna, Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Theraphy, Vienna (Austria)

    2013-12-15

    There is still a significant amount of patients who do not sufficiently respond to cardiac resynchronization therapy (CRT). Previous studies demonstrated that the amount of dyssynchronous myocardium was predictive of response to CRT. Otherwise, non-response is frequently associated with high amounts of scar tissue. The combination of these parameters might yield a more accurate prediction of response. We hypothesized that the probability of a CRT response increases with the presence of high amounts of ''viable and dyssynchronous'' myocardium. A total of 19 patients (17 male, 61 {+-} 10 years) underwent ECG-gated [{sup 18}F]fluorodeoxyglucose (FDG) myocardial positron emission tomography (PET) before CRT device implantation and were followed for 6 months. Response to CRT was defined as clinical improvement of at least one New York Heart Association (NYHA) class in combination with left ventricular (LV) ejection fraction (EF) improvement of >5 %. Twelve responders (71 %) and seven non-responders (29 %) were identified. For each patient bullseye maps of FDG uptake and phase analysis were calculated (QPS/QGS 2012, Cedars-Sinai, Los Angeles, CA, USA) and fused. Amounts of myocardium representing ''viable and synchronous'', ''scar and synchronous'', viable and dyssynchronous or ''scar and dyssynchronous'' myocardium were quantified by planimetric measurements of the fused bullseye maps. Responders by definition showed significant decrease in NYHA class and significant increase of LVEF. Furthermore, a significantly higher amount of viable and dyssynchronous myocardium was found as compared to non-responders (21 {+-} 13 % vs 6 {+-} 5 %; p < 0.05). Combined assessment of myocardial viability and LV dyssynchrony is feasible using multiparametric [{sup 18}F]FDG PET and could improve conventional response prediction criteria for CRT. (orig.)

  20. Low axial drift stage and temperature controlled liquid cell for z-scan fluorescence correlation spectroscopy in an inverted confocal geometry.

    Science.gov (United States)

    Allgeyer, Edward S; Sterling, Sarah M; Neivandt, David J; Mason, Michael D

    2011-05-01

    A recent iteration of fluorescence correlation spectroscopy (FCS), z-scan FCS, has drawn attention for its elegant solution to the problem of quantitative sample positioning when investigating two-dimensional systems while simultaneously providing an excellent method for extracting calibration-free diffusion coefficients. Unfortunately, the measurement of planar systems using (FCS and) z-scan FCS still requires extremely mechanically stable sample positioning, relative to a microscope objective. As axial sample position serves as the inherent length calibration, instabilities in sample position will affect measured diffusion coefficients. Here, we detail the design and function of a highly stable and mechanically simple inverted microscope stage that includes a temperature controlled liquid cell. The stage and sample cell are ideally suited to planar membrane investigations, but generally amenable to any quantitative microscopy that requires low drift and excellent axial and lateral stability. In the present work we evaluate the performance of our custom stage system and compare it with the stock microscope stage and typical sample sealing and holding methods.

  1. Low axial drift stage and temperature controlled liquid cell for z-scan fluorescence correlation spectroscopy in an inverted confocal geometry

    Energy Technology Data Exchange (ETDEWEB)

    Allgeyer, Edward S. [Department of Physics and Astronomy, University of Maine, Orono, Maine 04469 (United States); Sterling, Sarah M. [Graduate School of Biomedical Sciences, University of Maine, Orono, Maine 04469 (United States); Department of Chemical and Biological Engineering, University of Maine, Orono, Maine 04469 (United States); Neivandt, David J. [Graduate School of Biomedical Sciences, University of Maine, Orono, Maine 04469 (United States); Department of Chemical and Biological Engineering, University of Maine, Orono, Maine 04469 (United States); Institute for Molecular Biophysics, Orono, Maine 04469 (United States); Mason, Michael D. [Department of Chemical and Biological Engineering, University of Maine, Orono, Maine 04469 (United States); Institute for Molecular Biophysics, Orono, Maine 04469 (United States)

    2011-05-15

    A recent iteration of fluorescence correlation spectroscopy (FCS), z-scan FCS, has drawn attention for its elegant solution to the problem of quantitative sample positioning when investigating two-dimensional systems while simultaneously providing an excellent method for extracting calibration-free diffusion coefficients. Unfortunately, the measurement of planar systems using (FCS and) z-scan FCS still requires extremely mechanically stable sample positioning, relative to a microscope objective. As axial sample position serves as the inherent length calibration, instabilities in sample position will affect measured diffusion coefficients. Here, we detail the design and function of a highly stable and mechanically simple inverted microscope stage that includes a temperature controlled liquid cell. The stage and sample cell are ideally suited to planar membrane investigations, but generally amenable to any quantitative microscopy that requires low drift and excellent axial and lateral stability. In the present work we evaluate the performance of our custom stage system and compare it with the stock microscope stage and typical sample sealing and holding methods.

  2. Comparative study of image quality and radiation dose between prospective and retrospective ECG gating technique in coronary artery imaging with 64-slice spiral CT%64排螺旋CT冠状动脉成像的前瞻性与回顾性心电门控技术的图像质量及辐射剂量的比较研究

    Institute of Scientific and Technical Information of China (English)

    刘建新; 刘剑; 窦砚彬; 王继琛; 孙洪跃

    2009-01-01

    目的 研究前瞻性心电门控触发(prospective ECG-triggering)与回顾性心电门控(retrosp-ective ECG gating)两种技术方法行冠状动脉CTA检查时,对冠状动脉图像质量及辐射剂量的比较.方法 33名疑似冠状动脉疾病的患者分两组进行对比研究.前瞻组16例为前瞻性心电门控成像,心率小于65次/min;回顾组17例为回顾性心电门控成像,心率小于75次/min.记录两组的辐射剂量并统计分析,同时进行图像质量评价.结果 两组图像质量比较,差异无统计学意义(P0.05).前瞻性心电门控冠状动脉CTA的平均DLP 234.4 mGy·cm,占回顾性心电门控冠状动脉CTA的平均DLP 974.4 mGy·cm的24.1%.前瞻性心电门控冠状动脉CTA的患者的平均有效剂量为3.2 mSy,回顾心电门控冠状动脉CTA患者的为13.6 mSv,降低76.47%.结论 64排螺旋CT在前瞻性心电门控冠状动脉CTA与回顾性心电门控冠状动脉CTA比较可以获得相似的图像质量,可大幅降低患者的有效剂量对于不能接受高辐射剂量且心率较低的受检人群具有重要的临床价值.%Objective To compare the image quality and radiation dose between prospective ECG-trigering and retrospective ECG gating technique in coronary artery imaging. Methods 33 patients suspected coronary artery disease were included in this study and divided into experimental group (prospective ECG-triggering coronary artery imaging, heart rate < 65 bpm, 16 patients)and control group (retrospective ECG gating coronary artery imaging, heart rate < 75 bpm, 17 patients). Radiation dose was recorded for statistical analysis. At the same time, image quality was evaluated. Results There were no significant differences in image quality 3.2 msy. Effective dose reduced 76.47 %. Conclusions Prospective ECG gating coronary artery imaging can obtain the similar image quality compared with prospective ECG gating coronary artery imaging but the effective dose reduced 76.47 %. Prospective ECG

  3. Accuracy of finite element analyses of CT scans in predictions of vertebral failure patterns under axial compression and anterior flexion.

    Science.gov (United States)

    Jackman, Timothy M; DelMonaco, Alex M; Morgan, Elise F

    2016-01-25

    Finite element (FE) models built from quantitative computed tomography (QCT) scans can provide patient-specific estimates of bone strength and fracture risk in the spine. While prior studies demonstrate accurate QCT-based FE predictions of vertebral stiffness and strength, the accuracy of the predicted failure patterns, i.e., the locations where failure occurs within the vertebra and the way in which the vertebra deforms as failure progresses, is less clear. This study used digital volume correlation (DVC) analyses of time-lapse micro-computed tomography (μCT) images acquired during mechanical testing (compression and anterior flexion) of thoracic spine segments (T7-T9, n=28) to measure displacements occurring throughout the T8 vertebral body at the ultimate point. These displacements were compared to those simulated by QCT-based FE analyses of T8. We hypothesized that the FE predictions would be more accurate when the boundary conditions are based on measurements of pressure distributions within intervertebral discs of similar level of disc degeneration vs. boundary conditions representing rigid platens. The FE simulations captured some of the general, qualitative features of the failure patterns; however, displacement errors ranged 12-279%. Contrary to our hypothesis, no differences in displacement errors were found when using boundary conditions representing measurements of disc pressure vs. rigid platens. The smallest displacement errors were obtained using boundary conditions that were measured directly by DVC at the T8 endplates. These findings indicate that further work is needed to develop methods of identifying physiological loading conditions for the vertebral body, for the purpose of achieving robust, patient-specific FE analyses of failure mechanisms.

  4. Evaluation of image quality and radiation dose at prospective ECG-triggered axial 256-slice multi-detector CT in infants with congenital heart disease

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Mei-ping; Liang, Chang-hong; Zhao, Zhen-jun; Liu, Hui; Li, Jing-lei; Zhang, Jin-e; Cui, Yan-hai; Yang, Lin; Liu, Qi-shun [Guangdong Academy of Medical Sciences, Guangdong General Hospital, Department of Radiology, Guangzhou (China); Ivanc, Thomas B.; Vembar, Mani [Philips Healthcare, CT Clinical Science, Highland Heights, OH (United States)

    2011-07-15

    There are a limited number of reports on the technical and clinical feasibility of prospective electrocardiogram (ECG)-gated multi-detector computed tomography (MDCT) in infants with congenital heart disease (CHD). To evaluate image quality and radiation dose at weight-based low-dose prospectively gated 256-slice MDCT angiography in infants with CHD. From November 2009 to February 2010, 64 consecutive infants with CHD referred for pre-operative or post-operative CT were included. All were scanned on a 256-slice MDCT system utilizing a low-dose protocol (80 kVp and 60-120 mAs depending on weight: 60 mAs for {<=}3 kg, 80 mAs for 3.1-6 kg, 100 mAs for 6.1-10 kg, 120 mAs for 10.1-15 kg). No serious adverse events were recorded. A total of 174 cardiac deformities, confirmed by surgery or heart catheterization, were studied. The sensitivity of MDCT for cardiac deformities was 97.1%; specificity, 99.4%; accuracy, 95.9%. The mean heart rate during scan was 136.7 {+-} 14.9/min (range, 91-160) with a corresponding heart rate variability of 2.8 {+-} 2.2/min (range, 0-8). Mean scan length was 115.3 {+-} 11.7 mm (range, 93.6-143.3). Mean volume CT dose index, mean dose-length product and effective dose were 2.1 {+-} 0.4 mGy (range, 1.5-2.8), 24.7 {+-} 5.9 mGy.cm (range, 14.7-35.8) and 1.6 {+-} 0.3 mSv (range, 1.1-2.5), respectively. Diagnostic-quality images were achieved in all cases. Satisfactory diagnostic quality for visualization of all/proximal/distal coronary artery segments was achieved in 88.4/98.8/80.0% of the scans. Low-dose prospectively gated axial 256-slice CT angiography is a valuable tool in the routine clinical evaluation of infants with CHD, providing a comprehensive three-dimensional evaluation of the cardiac anatomy, including the coronary arteries. (orig.)

  5. Lumbar spine CT scan

    Science.gov (United States)

    CAT scan - lumbar spine; Computed axial tomography scan - lumbar spine; Computed tomography scan - lumbar spine; CT - lower back ... your breath for short periods of time. The scan should take only 10 to 15 minutes.

  6. CT imaging before transcatheter aortic valve implantation (TAVI) using variable helical pitch scanning and its diagnostic performance for coronary artery disease

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Shunsuke; Yamada, Yoshitake; Hashimoto, Masahiro; Okamura, Teppei; Jinzaki, Masahiro [Keio University School of Medicine, Department of Diagnostic Radiology, Shinanomachi, Shinjuku-ku, Tokyo (Japan); Yamada, Minoru [Keio University School of Medicine, Research Park, Tokyo (Japan); Yashima, Fumiaki; Hayashida, Kentaro; Fukuda, Keiichi [Keio University School of Medicine, Department of Cardiology, Tokyo (Japan)

    2017-05-15

    To evaluate the effectiveness of CT before TAVI using variable helical pitch (VHP) scanning and its diagnostic performance for coronary artery disease (CAD). Sixty patients (84.4 ± 4.6 years) scheduled for TAVI underwent CT using VHP scanning with the contrast material (CM) volume calculated as scanning time x weight [kg] x 0.06 mL. Retrospective electrocardiography (ECG)-gated scanning was utilized to examine the thorax, and non-ECG-gated scanning of the abdomen immediately followed. We analyzed CT attenuation values of the coronary arteries, aorta, iliac and femoral arteries. The coronary CT angiography images were evaluated for the presence of stenosis (≥50 %); invasive coronary angiography served as a reference standard. The average attenuations of all of the arteries were greater than 400 HU. We could evaluate the peripheral access vessels and dimensions of the ascending aorta, aortic root, and aortic annulus in all patients. The average volume of CM was 38.7 ± 8.5 mL. On per-patient and vessel analysis, CT showed 91.7 % and 89.5 % sensitivity, and 91.3 % and 97.4 % negative predictive value (NPV). CT using VHP scanning with an average CM volume of 38.7 mL is useful before TAVI and had a high sensitivity and NPV in excluding obstructive CAD. (orig.)

  7. The impact of x-ray tube stabilization on localized radiation dose in axial CT scans: initial results in CTDI phantoms

    Science.gov (United States)

    Mathieu, Kelsey B.; McNitt-Gray, Michael F.; Cody, Dianna D.

    2016-10-01

    Rise, fall, and stabilization of the x-ray tube output occur immediately before and after data acquisition on some computed tomography (CT) scanners and are believed to contribute additional dose to anatomy facing the x-ray tube when it powers on or off. In this study, we characterized the dose penalty caused by additional radiation exposure during the rise, stabilization, and/or fall time (referred to as overscanning). A 32 cm CT dose-index (CTDI) phantom was scanned on three CT scanners: GE Healthcare LightSpeed VCT, GE Healthcare Discovery CT750 HD, and Siemens Somatom Definition Flash. Radiation exposure was detected for various x-ray tube start acquisition angles using a 10 cm pencil ionization chamber placed in the peripheral chamber hole at the phantom’s 12 o’clock position. Scan rotation time, ionization chamber location, phantom diameter, and phantom centering were varied to quantify their effects on the dose penalty caused by overscanning. For 1 s single, axial rotations, CTDI at the 12 o’clock chamber position (CTDI100, 12:00) was 6.1%, 4.0%, and 4.4% higher when the start angle of the x-ray tube was aligned at the top of the gantry (12 o’clock) versus when the start angle was aligned at 9 o’clock for the Siemens Flash, GE CT750 HD, and GE VCT scanner, respectively. For the scanners’ fastest rotation times (0.285 s for the Siemens and 0.4 s for both GE scanners), the dose penalties increased to 22.3%, 10.7%, and 10.5%, respectively, suggesting a trade-off between rotation speed and the dose penalty from overscanning. In general, overscanning was shown to have a greater radiation dose impact for larger diameter phantoms, shorter rotation times, and to peripheral phantom locations. Future research is necessary to determine an appropriate method for incorporating the localized dose penalty from overscanning into standard dose metrics, as well as to assess the impact on organ dose.

  8. Axial myopathy

    DEFF Research Database (Denmark)

    Witting, Nanna; Andersen, Linda K; Vissing, John

    2016-01-01

    musculature involvement in the majority of myopathies in which paraspinal musculature was examined. Even in diseases named after a certain pattern of non-axial muscle affection, such as facioscapulohumeral and limb girdle muscular dystrophies, affection of the axial musculature was often severe and early...

  9. Comparison of image quality between axial and spiral scan mode in routine head CT%常规头部CT螺旋扫描与轴扫描模式的影像质量对照

    Institute of Scientific and Technical Information of China (English)

    傅强; 刘晓菲; 于虹; 徐克

    2012-01-01

    目的 通过头部CT螺旋扫描和轴扫描两种不同扫描模式的影像质量对照,探讨常规头部CT采用螺旋扫描模式取代轴扫描模式的可行性.方法 40例患者,其中男性24例,女性16例;年龄18 ~ 74岁,平均年龄46岁.分别接受头部CT螺旋扫描和轴扫描两种不同模式扫描,轴扫描参数:140 kV、170 mA用于颅底部;120 kV、150 mA用于颅脑部,每周2s.螺旋扫描参数:120 kV,150 mA,每周0.6 s.扫描剂量直接取自设备剂量指示值(CTDI和DLP).影像质量分别由2位专家采用双盲法,对头部CT的颅底、脑灰-白质层面及全部影像逐层进行CT值测量评估.结果 常规头部CT螺旋扫描模式较轴扫描模式可有效去除颅底部伪影,并能减少扫描时间和扫描剂量(轴扫描模式与螺旋扫描模式对比,CTDI 55.43 mGy/37.80 mGy;DLP 662.10 mGy· cm/498.28 mGy· cm;扫描时间12.0 s/7.2 s)(P< 0.001).结论 常规头部CT螺旋扫描模式的影像质量完全可与轴扫描模式相媲美,并可取代轴扫描模式.同时常规头部CT螺旋扫描模式还具有可减少扫描时间和辐射剂量,并可进行影像的二维和三维后处理,有利于提高微小病灶正确诊断率的优越性.%Objective To assess the feasibility of replacing axial CT scan mode with spiral CT scan mode in routine head CT through comparing the image quality between spiral and routine axial (sequential) acquired head CT. Methods A total of 40 cases were enrolled, male 24, female 16; aged 18 - 74 years old, mean age 46 years old. They were performed spiral scan and axial scan, respectively. Scan parameter axial mode were 140 kV, 170 mA for petrou bone, and 120 kV, 150 mA for brain, scan time 2.0 s/rol; and spiral mode were 120 kV, 150 mA, scan time 0.6 s/rol. Radiation dose were measured directly from the CT scan indicated computed tomography dose index (CTDI) and dose-length product (DLP). The image quality at the level of the posterior fossa and grey -white matter

  10. Tube current modulation based on the lateral chest diameter and CT value on a scout view in prospectively ECG-gated CT coronary angiography%定位像胸部横径与CT值调制前瞻性序列扫描冠状动脉成像管电流的研究

    Institute of Scientific and Technical Information of China (English)

    舒荣宝; 仝开军; 王岳松; 严芳; 罗潇; 董学滨; 周华飞; 章聪

    2015-01-01

    Objective To investigate the clinical value of the patient's individually tube current modulation based on the lateral chest diameter (LD) and average CT value (CTchest) on a scout view in prospectively ECG-gated CT coronary angiography (PG CTCA).Methods Totally 194 consecutive patients were randomly divided into three groups:Group RG (retrospectively ECG-gated CTCA,69 patients,standard protocol with a fixed 600 mA),Group PG1 (prospectively ECG-gated CTCA,68 patients) and PG2 (the control group,57 patients).On the scout AP view,the chest LD was measured at the upper border of T10 vertebra;and the density (CTchest) was measured at the intercostal space of right midclavicular line above the diaphragm.The chest anteroposterior diameter (APD) were measured at the same level on the scout lateral view.The CTCA image noise was measured at the root of ascending aorta.A tube current conversion formula and quick list were conducted after matching the measured parameters with the noise.The tube current (mA) used in PG1 was determined by the list established previously.The tube current used in group PG2 wad fixed with reference to body mass (400 mA when < 77 kg;500 mA when ≥77 kg).The image quality scores,image noise,volume CT dose index(CTDIvol),and effective dose(E) were evaluated for each patient.LD,CTchest CTDIvol,DLP,E and image noise were all analyzed using one-way ANOVA analysis among 3 groups.And the image quality scores of the coronary artery were analyzed using R × 2 contingency tables x2 test.Results The tube current conversion formnula was as mA=600/282.(0.487LD+0.064CTchest + 13.7)2(R2 =0.53,F =36.13,P =0.00).There were no statistical differences among three groups in LD and CTchest on the scout view (P > 0.05).There were magnificent statistical differences among three groups in SD,mA,and CTDIvol (F =44.96,167.37,1 071.26,P<0.05),There were also no statistical difference on image quality scores and the assessable vessels among 3 groups(x2 =6.89,2.54,P

  11. Change perspective to increase diagnostic accuracy of ultrasonography in calcium pyrophosphate dihydrate deposition disease! A new approach: the axial scan of the meniscus

    Directory of Open Access Journals (Sweden)

    G. Filippou

    2015-03-01

    Full Text Available Ultrasonography (US is a relevant tool in the study of calcium pyrophosphate dihydrate (CPP deposition disease. However, differential diagnosis of hyperechoic deposits within the fibrocartilage can be difficult; moreover, US study is limited by the need of an adequate acoustic window. We describe a US scanning technique that offers a new viewpoint in the study of knee meniscal structure: a longitudinal scan performed according to the long axis of meniscus. This technique proves to be particularly useful for the identification of CPP deposition, but could also improve the US diagnostic utility and accuracy in other meniscal pathologies.

  12. Evaluation of retrospectively ECG-gated 4-row multidetector CT in patients planned for minimal invasive coronary artery bypass grafting; Die EKG-getriggerte 4-Zeilen-Spiral-CT des Herzens in der praeoperativen Bildgebung vor minimalinvasiver koronarer Bypass-Operation

    Energy Technology Data Exchange (ETDEWEB)

    Begemann, P.G.C.; Ittrich, H.; Koops, A.; Adam, G.; Weber, C. [Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie, Radiologisches Zentrum, Universitaetsklinikum, Hamburg (Germany); Arnold, M.; Detter, C.; Boehm, D.H.; Reichenspurner, H. [Universitaetsklinikum Hamburg-Eppendorf, Herzzentrum, Herz und Gefaesschirurgie, Hamburg (Germany)

    2005-08-01

    Purpose: Minimal invasive direct coronary artery bypass grafting (MIDCAB) or off-pump coronary artery bypass grafting (OPCAB) on the beating heart with full or mini-sternotomy are becoming more common in coronary bypass surgery of the left anterior descending (LAD). In the decision, which surgical approach (MIDCAB, OPCAB or conventional surgery with cardiopulmonary bypass) will be best used, knowledge of the anatomical field is of major importance. The aim of the study was to evaluate retrospective ECG-gated 4-row multidetector CT (MDCT) in patients planned for MIDCAB as additional imaging to coronary angiography. Material and methods: The study included 25 consecutive patients. MSCT was performed as unenhanced (collimation 4 x 2.5 mm) and contrast-enhanced examination (140-170 ml, 300 mg Iodine/ml, collimation 4 x 1 mm). The evaluation included presence of LAD calcifications, distance of LAD and left internal mammarian artery (LIMA), coursek of LAD and LIMA, the presence or absence of bridging through myocardium or epicardial fat and the presence of pleural fibrosis. The MDCT results were correlated with intra-operative findings. Results: All MDCTs could be assessed with reference to the demands. In 20/25 operations, MDCT had direct influence as to the selection of the surgical approach (11 MIDCAB, 7 OPCAB with mini-sternotomy and 5 with full sternotomy, 2 conventional surgeries). The distance of LAD and LIMA varied from 0.9 to 4.5 cm in MDCT. As to calcifications, 3/25 correlated patients had calcifications and 10 patients had no calcifications in the middle LAD. Seven patients had intraoperative fibrosis of the vessel wall without calcification of the middle LAD, which could not be detected with MDCT. Another 5 patients had single calcified plaques in the middle LAD, 4 of these had a fibrosis of the vessel and 1 had a normal vessel at surgery. In these cases, the anastomosis was done between the calcified plaques. No myocardial bridging was detected by MDCT and

  13. Light axial vector mesons

    CERN Document Server

    Chen, Kan; Liu, Xiang; Matsuki, Takayuki

    2015-01-01

    Inspired by the abundant experimental observation of axial vector states, we study whether the observed axial vector states can be categorized into the conventional axial vector meson family. In this paper we carry out analysis based on the mass spectra and two-body Okubo-Zweig-Iizuka-allowed decays. Besides testing the possible axial vector meson assignments, we also predict abundant information for their decays and the properties of some missing axial vector mesons, which are valuable to further experimental exploration of the observed and predicted axial vector mesons.

  14. The value of axial T2WI fat saturation sequence scan in diagnosing the medial patellar retinaculum injury%压脂轴位T2加权成像在髌骨内侧支持带损伤诊断中的价值

    Institute of Scientific and Technical Information of China (English)

    吕贻民; 张允; 熊鹏飞

    2014-01-01

    目的:探讨压脂轴位T2加权成像(T2WI)在髌骨内侧支持带损伤诊断中的价值。方法对比分析21例髌骨内侧支持带损伤患者在轴位T2WI、压脂轴位T2WI和冠状位T2WI上的磁共振表现。结果3种扫描方式在信号异常方面的差异有统计学意义(P<0.05),经多重比较,示压脂轴位T2WI组扫描方式优于其他2组扫描方式。间接征象方面的差异有统计学意义。结论压脂轴位T2WI能很好地显示髌骨内侧支持带损伤的直接和间接征象,具有很高的诊断价值。%Objective To investigate the diagnostic value of axial T2WI fat saturation sequence scan in medial patellar retinaculum injury. Methods To compare and analyze the MR findings of 21 cases of medial patellar reti-naculum injury in patients with axial T2WI, axial T2WI fat saturation and coronal T2WI. Results There were signifi-cant differences between the three scanning modes in the abnormal signal area (P<0.05), by comparison, axial T2WI fat saturation sequence scan was better than the other two groups in scanning mode. The difference was statistically significant for indirect signs. Conclusion Axial T2WI fat saturation sequence scan can well display the direct and in-direct signs of medial patellar retinaculum injury, which has highly diagnostic value.

  15. Altered carotid plaque signal among different repetition times on T1-weighted magnetic resonance plaque imaging with self-navigated radial-scan technique

    Energy Technology Data Exchange (ETDEWEB)

    Narumi, Shinsuke; Ohba, Hideki; Mori, Kiyofumi; Ohura, Kazumasa; Ono, Ayumi; Terayama, Yasuo [Iwate Medical University, Department of Neurology and Gerontology, Morioka (Japan); Sasaki, Makoto [Iwate Medical University, Advanced Medical Research Center, Morioka (Japan); Ogasawara, Kuniaki [Iwate Medical University, Department of Neurosurgery, Morioka (Japan); Hitomi, Jiro [Iwate Medical University, Department of Anatomy, Morioka (Japan)

    2010-04-15

    Magnetic resonance (MR) plaque imaging for carotid arteries is usually performed by using an electrocardiograph (ECG)-gating technique to eliminate pulsation-related artifacts, which can affect the plaque signals because of varied repetition time (TR) among patients. Hence, we investigated whether differences in TR causes signal alterations of the carotid plaque by using a non-gated plaque imaging technique. We prospectively examined 19 patients with carotid stenosis by using a T1-weighted self-navigated radial-scan technique with TRs of 500, 700, and 900 ms. The signal intensity of the carotid plaque was measured, and the contrast ratio (CR) relative to the adjacent muscle was calculated. CRs of the carotid plaques were 1.39 {+-} 0.39, 1.29 {+-} 0.29, and 1.23 {+-} 0.24 with TRs of 500, 700, and 900 ms, respectively, and were significantly different. Among the plaques, those with a hyperintensity signal (CR > 1.5) and moderate-intensity signal (CR 1.2-1.5) at 500 ms showed a TR-dependent signal decrease (hyperintensity plaques, 1.82 {+-} 0.26; 1.61 {+-} 0.19; and 1.48 {+-} 0.17; moderate-intensity plaques, 1.33 {+-} 0.08; 1.26 {+-} 0.08; and 1.19 {+-} 0.07), while those with an isointensity signal (CR < 1.2) remained unchanged regardless of TR (0.96 {+-} 0.12, 0.96 {+-} 0.11, and 0.97 {+-} 0.13). The signal intensity of the carotid plaque on T1-weighted imaging significantly varies among different TRs and tends to decrease with longer TR. MR plaque imaging with short and constant TR settings that the ECG-gating method cannot realize would be preferable for evaluating plaque characteristics. (orig.)

  16. Cardiac imaging in diagnostic VCT using multi-sector data acquisition and image reconstruction: step-and-shoot scan vs. helical scan

    Science.gov (United States)

    Tang, Xiangyang; Hsieh, Jiang; Seamans, John L.; Dong, Fang; Okerlund, Darin

    2008-03-01

    Since the advent of multi-slice CT, helical scan has played an increasingly important role in cardiac imaging. With the availability of diagnostic volumetric CT, step-and-shoot scan has been becoming popular recently. Step-and-shoot scan decouples patient table motion from heart beating, and thus the temporal window for data acquisition and image reconstruction can be optimized, resulting in significantly reduced radiation dose, improved tolerance to heart beat rate variation and inter-cycle cardiac motion inconsistency. Multi-sector data acquisition and image reconstruction have been utilized in helical cardiac imaging to improve temporal resolution, but suffers from the coupling of heart beating and patient table motion. Recognizing the clinical demands, the multi-sector data acquisition scheme for step-and-shoot scan is investigated in this paper. The most outstanding feature of the multi-sector data acquisition combined with the stepand- shoot scan is the decoupling of patient table proceeding from heart beating, which offers the opportunities of employing prospective ECG-gating to improve dose efficiency and fine adjusting cardiac imaging phase to suppress artifacts caused by inter-cycle cardiac motion inconsistency. The improvement in temporal resolution and the resultant suppression of motion artifacts are evaluated via motion phantoms driven by artificial ECG signals. Both theoretical analysis and experimental evaluation show promising results for multi-sector data acquisition scheme to be employed with the step-and-shoot scan. With the ever-increasing gantry rotation speed and detector longitudinal coverage in stateof- the-art VCT scanners, it is expected that the step-and-shoot scan with multi-sector data acquisition scheme would play an increasingly important role in cardiac imaging using diagnostic VCT scanners.

  17. BWR AXIAL PROFILE

    Energy Technology Data Exchange (ETDEWEB)

    J. Huffer

    2004-09-28

    The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I.

  18. [Management of axial spondyloarthritis].

    Science.gov (United States)

    Kiltz, U; Baraliakos, X; Braun, J

    2016-11-01

    The term spondyloarthritis (SpA) is now increasingly used to classify and diagnose patients who are characterized by inflammation in the axial skeleton and peripheral manifestations (arthritis and enthesitis). The management of SpA should be tailored according to the current manifestations of the disease, the disease activity and functional impairment. The current article focuses on diagnosis and therapy in patients with axial SpA. Diagnostic procedures are discussed in light of diagnostic utility and feasibility in daily routine care. Cornerstones of treatment in patients with axial SpA are a combination of regular exercise and pharmacological treatment options aiming at anti-inflammatory strategies.

  19. Axial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  20. Auto-calibrated scanning-angle prism-type total internal reflection microscopy for nanometer-precision axial position determination and optional variable-illumination-depth pseudo total internal reflection microscopy

    Science.gov (United States)

    Fang, Ning; Sun, Wei

    2015-04-21

    A method, apparatus, and system for improved VA-TIRFM microscopy. The method comprises automatically controlled calibration of one or more laser sources by precise control of presentation of each laser relative a sample for small incremental changes of incident angle over a range of critical TIR angles. The calibration then allows precise scanning of the sample for any of those calibrated angles for higher and more accurate resolution, and better reconstruction of the scans for super resolution reconstruction of the sample. Optionally the system can be controlled for incident angles of the excitation laser at sub-critical angles for pseudo TIRFM. Optionally both above-critical angle and sub critical angle measurements can be accomplished with the same system.

  1. Altered Axial Skeletal Development

    Science.gov (United States)

    The axial skeleton is routinely examined in standard developmental toxicity bioassays and has proven to be sensitive to a wide variety of chemical agents. Dysmorphogenesis in the skull, vertebral column and ribs has been described in both human populations and in laboratory anima...

  2. Clinical evauation on axial length and intraocular lens power measurementin silicone oil-filled eyes using A-scan ultrasound%A超测量硅油填充眼眼轴及人工晶状体度数的临床评价

    Institute of Scientific and Technical Information of China (English)

    康欣乐; 李明新

    2013-01-01

    Objective To evaluate the accuracy of axial length and intraocular lens (IOL) measurement in silicone oil - filled eyes using A - scan ultrasound. Methods The cuvette was put with the silicone oil taken from the patients ' eyes, pure silicone oil and balanced salt solution. The speed of ultrasonic wave in these solvent was measured with empir -ical method using Compat tach Ⅱ A/B acoustic instrument of French QUANTEL MEDICAL company . Then the measured axial length was corrected to evaluate the accurate power of IOL . 25 patients who had vitrectomy and silicone oil filled surgery were collected. Firstly, using the recognized acoustic speed of 0x5700 to measure the axial length of the sick eye. Secondly, using the speed by our experiment to measure the sick eye in sitting position and in supine position . Fi-naly, the power of IOL was then calculated through SRK II formula by the axial length in sitting position. They received silicone oil extraction and cataract phacoemulsification and IOL implantation in one operation . 3 months after surgery, all eyes were reexamined and the actual axial length were measured again . The eye axial length and the best correct visual a -cuity were compared before and after the operation. The postoperative refraction and preoperative expected refraction was compared. Results The mean width of colorimetric cuvettes filled with pure Ox5700 silicone oil was (31.440 ±0.011) mm, that filled with the oil taken from patients' eyes was (31.420 ± 0.047 ) mm. There was no difference between them. The width of colorimetric cuvettes filled with the balanced salt solution was 21.07 mm. The recognized acoustic speed of Ox5700 silicone oil was 990 m/s. Before the surgrey, the mean axial length under the acoustic speed of 990 m/s in sili-cone oil tamponade eyes was (23. 219 ±0.125) mm. The mean axial length under the acoustic speed of 1 027m/s in sili-cone oil tamponade eyes was (24. 103 ±0. 135) mm in sitting position and was (24. 116 ±0. 128

  3. Axial myopia in computed and magnetic resonance tomography

    Energy Technology Data Exchange (ETDEWEB)

    Beyer-Enke, S.A.; Goerich, J.; Gamroth, A.

    1987-08-01

    The case of a 44-year old woman suffering from amblyopia on the left eye with unilateral proptosis caused by axial (progressive) myopia is presented. The clinical and radiological findings were discussed in reference to the literature. The diagnosis was established by ruling out neoplastic, inflammatory or endocrine causes for the exophtalmos. CT and MR scans revealed an enlarged left globe without evidence of orbital masses. The findings were regarded as typical for the diagnosis at axial myopia.

  4. Surface nanoscale axial photonics

    CERN Document Server

    Sumetsky, M

    2011-01-01

    Dense photonic integration promises to revolutionize optical computing and communications. However, efforts towards this goal face unacceptable attenuation of light caused by surface roughness in microscopic devices. Here we address this problem by introducing Surface Nanoscale Axial Photonics (SNAP). The SNAP platform is based on whispering gallery modes circulating around the optical fiber surface and undergoing slow axial propagation readily described by the one-dimensional Schr\\"odinger equation. These modes can be steered with dramatically small nanoscale variation of the fiber radius, which is quite simple to introduce in practice. The extremely low loss of SNAP devices is achieved due to the fantastically low surface roughness inherent in a drawn fiber surface. In excellent agreement with the developed theory, we experimentally demonstrate localization of light in quantum wells, halting light by a point source, tunneling through potential barriers, dark states, etc. This demonstration, prototyping basi...

  5. Piping inspection carriage having axially displaceable sensor

    Science.gov (United States)

    Zollinger, William T.; Treanor, Richard C.

    1994-01-01

    A pipe inspection instrument carriage for use with a pipe crawler for performing internal inspections of piping surfaces. The carriage has a front leg assembly, a rear leg assembly and a central support connecting the two assemblies and for mounting an instrument arm having inspection instruments. The instrument arm has a y-arm mounted distally thereon for axially aligning the inspection instrumentation and a mounting block, a linear actuator and axial movement arm for extending the inspection instruments radially outward to operably position the inspection instruments on the piping interior. Also, the carriage has a rotation motor and gear assembly for rotating the central support and the front leg assembly with respect to the rear leg assembly so that the inspection instruments azimuthally scan the piping interior. The instrument carriage allows performance of all piping inspection operations with a minimum of moving parts, thus decreasing the likelihood of performance failure.

  6. Critical Axial Load

    Directory of Open Access Journals (Sweden)

    Walt Wells

    2008-01-01

    Full Text Available Our objective in this paper is to solve a second order differential equation for a long, simply supported column member subjected to a lateral axial load using Heun's numerical method. We will use the solution to find the critical load at which the column member will fail due to buckling. We will calculate this load using Euler's derived analytical approach for an exact solution, as well as Euler's Numerical Method. We will then compare the three calculated values to see how much they deviate from one another. During the critical load calculation, it will be necessary to calculate the moment of inertia for the column member.

  7. Nuclear Scans

    Science.gov (United States)

    Nuclear scans use radioactive substances to see structures and functions inside your body. They use a special ... images. Most scans take 20 to 45 minutes. Nuclear scans can help doctors diagnose many conditions, including ...

  8. Getting a CAT Scan (For Kids)

    Science.gov (United States)

    ... What Happens in the Operating Room? Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) A A A en español Obtención de una tomografía computada (video) CAT stands for "computerized axial tomography." Translated, that means ...

  9. Getting a CAT Scan (For Kids)

    Medline Plus

    Full Text Available ... Know About Puberty Train Your Temper Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A A en español Obtención de una tomografía computada (video) CAT stands for "computerized axial tomography." Translated, that means ...

  10. Application of low dose radiation and low concentration contrast media in enhanced CT scans in children with congenital heart disease.

    Science.gov (United States)

    Liu, Zhimin; Song, Lei; Yu, Tong; Gao, Jun; Zhang, Qifeng; Jiang, Ling; Liu, Yong; Peng, Yun

    2016-09-01

    The aim of this study was to explore the feasibility of using low dose radiation and low concentration contrast media in enhanced CT examinations in children with congenital heart disease. Ninety patients with congenital heart disease were randomly divided into three groups of 30 patients each who underwent contrast-enhanced cardiac scans on a Discovery CT750 HD scanner. Group A received 270 mg I/mL iodixanol, and group B received 320 mg I/mL iodixanol contrast media and was scanned with prospective ECG triggering mode. Group C received 320 mg I/mL iodixanol and was scanned with conventional retrospective ECG gating mode. The same weight-based contrast injection protocol was used for all three groups. Images were reconstructed using a 30% adaptive statistical iterative reconstruction (ASIR) algorithm and a 50% ASIR in groups A and B and a 30% ASIR in group C. The subjective and objective image quality evaluations, diagnostic accuracies, radiation doses and amounts of contrast media in the three groups were measured and compared. All images in the three groups met the diagnostic requirements, with the same diagnostic accuracy and image quality scores greater than 3 in a 4-point scoring system. However, ventricular enhancement and the objective noise, signal-to-noise ratio, contrast-to-noise ratio and subjective image quality scores in group C were better than those in groups A and B (all Pconcentration contrast media can meet the diagnostic requirements for examining children with congenital heart disease while reducing the potential risk of radiation damage and contrast-induced nephropathy. © 2016 John Wiley & Sons Ltd.

  11. Build Axial Gradient Field by Using Axial Magnetized Permanent Rings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Axial magnetic field produced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be produced. If they are magnetized in opposite direction,an axial gradient magnetic field can be generated, with the field range changing from -B0 to B0. A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the PANDIRA calculation very well. For wider usage,it is desirable for the field gradient to be changed. Some methods to produce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be produced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.

  12. 64-MDCT imaging of the coronary arteries and systemic arterial vascular tree in a single examination: optimisation of the scan protocol and contrast-agent administration.

    Science.gov (United States)

    Napoli, A; Anzidei, M; Francone, M; Cavallo Marincola, B; Carbone, I; Geiger, D; Zaccagna, F; Di Paolo, P L; Zini, C; Catalano, C; Passariello, R

    2008-09-01

    The aim of this study was to validate a 64-row multidetector computed tomography (64-MDCT) acquisition protocol with biphasic administration of contrast medium for comprehensive assessment of the coronary and systemic arterial tree in a single examination. The scanning protocol comprised two acquisitions: an electrocardiograph (ECG)-gated scan at the level of the heart, followed by a total-body, low-dose scan of the systemic arterial circulation. Twenty patients were evaluated using two different strategies for contrast administration. In ten patients, the delay between the two acquisitions was set at 40 s, whereas in the remaining patients, it varied between 45 s and 65 s. For both strategies, the degree of systemic arterial opacification and the attenuation gradient between arterial and venous structures were quantitatively assessed at six extracoronary locations. Two observers evaluated in consensus the presence or absence of atherosclerosis and the degree of stenosis of arterial segments. Three hundred coronary segments were analysed. Arterial-wall changes were depicted in 155 (51%) segments, and in 35 (23%), the degree of stenosis was > 50%. Of the 640 extracoronary arterial segments, 250 (39%) presented atherosclerotic wall alterations, in 50 (20%), the degree of stenosis was > 50% and five were affected by aneurysmal dilatation. The magnitude of arterial opacification values and attenuation gradients between arterial and venous structures were significantly higher in patients scanned with the 40-s fixed-delay strategy. Whole-body CT angiography with biphasic administration of contrast agent and fixed scan delay has been shown to be a feasible and reproducible technique. Comprehensive data on the global atherosclerotic burden potentially offer important therapeutic options for subclinical, high-risk segments.

  13. Dissipative Axial Inflation

    CERN Document Server

    Notari, Alessio

    2016-01-01

    We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\\frac{\\phi}{f_\\gamma} F \\tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $\\rho_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_\\gamma$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_\\gamma$ is smaller than the field excursion $\\phi_0$ by about a factor of at least ${\\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of...

  14. Investigation of axial power gradients near a control rod tip

    Energy Technology Data Exchange (ETDEWEB)

    Loberg, John, E-mail: John.Loberg@fysast.uu.se [Uppsala University, Department of Physics and Astronomy, Division of Applied Nuclear Physics, Box 525, SE-75120 Uppsala (Sweden); Osterlund, Michael, E-mail: Michael.Osterlund@fysast.uu.se [Uppsala University, Department of Physics and Astronomy, Division of Applied Nuclear Physics, Box 525, SE-75120 Uppsala (Sweden); Bejmer, Klaes-Hakan, E-mail: Klaes-Hakan.Bejmer@vattenfall.com [Vattenfall Nuclear Fuel AB, Jaemtlandsgatan 99, 162 60 Vaellingby, Stockholm (Sweden); Blomgren, Jan, E-mail: Jan.Blomgren@vattenfall.com [Vattenfall Nuclear Fuel AB, Jaemtlandsgatan 99, 162 60 Vaellingby, Stockholm (Sweden); Kierkegaard, Jesper, E-mail: Jesper.Kierkegaar@vattenfall.com [Vattenfall Nuclear Fuel AB, Jaemtlandsgatan 99, 162 60 Vaellingby, Stockholm (Sweden)

    2011-07-15

    Highlights: > Pin power gradients near BWR control rod tips have been investigated. > A control rod tip is modeled in MCNP and compared to simplified 2D/3D geometry. > Small nodes increases pin power gradients; standard nodes underestimates gradients. > The MCNP results are validated against axial gamma scan of a controlled fuel pin. - Abstract: Control rod withdrawal in BWRs induces large power steps in the adjacent fuel assemblies. This paper investigates how well a 2D/3D method, e.g., CASMO5/SIMULATE5 computes axial pin power gradients adjacent to an asymmetrical control-rod tip in a BWR. The ability to predict pin power gradients accurately is important for safety considerations whereas large powers steps induced by control rod withdrawal can cause Pellet Cladding Interaction. The computation of axial pin power gradients axially around a control rod tip is a challenging task for any nodal code. On top of that, asymmetrical control rod handles are present in some BWR designs. The lattice code CASMO requires diagonal symmetry of all control rod parts. This introduces an error in computed pin power gradients that has been evaluated by Monte Carlo calculations. The results show that CASMO5/SIMULATE5, despite the asymmetrical control rod handle, is able to predict the axial pin power gradient within 1%/cm for axial nodal sizes of 15-3.68 cm. However, a nodal size of 3.68 cm still causes underestimations of pin power gradients compared with 1 cm nodes. Furthermore, if conventional node sizes are used, {approx}15 cm, pin power gradients can be underestimated by over 50% compared with 1 cm nodes. The detailed axial pin power profiles from MCNP are corroborated by measured gamma scan data on fuel rods irradiated adjacent to control rods.

  15. Relationship Between Retinal Vein Occlusion and Axial Length

    Directory of Open Access Journals (Sweden)

    San-Chang Tsai

    2003-09-01

    Full Text Available This study examined whether axial length is a local risk factor for central retinal vein occlusion (CRVO and branch retinal vein occlusion (BRVO. The study group consisted of 40 patients with unilateral CRVO and 77 patients with unilateral BRVO. The control group included 67 individuals who matched the study group patients in age, systemic hypertension, and diabetes mellitus status. The axial lengths of affected and fellow eyes of patients and controls were measured using A-scan ultrasonography. The axial length of affected eyes was statistically significantly shorter than that of unaffected eyes in the BRVO group (p < 0.05 but not in the CRVO group (p = 0.05. There were also statistically significant differences in axial length between control eyes and affected eyes in both the CRVO group (p < 0.05 and BRVO group (p < 0.05. Thus, shorter axial length could be a risk factor for developing CRVO and BRVO. The axial lengths of affected eyes in retinal vein occlusion patients tend to be shorter than those of unaffected eyes, especially in BRVO patients.

  16. Coronary artery bypass graft imaging using ECG-gated multislice computed tomography: Comparison with catheter angiography

    Energy Technology Data Exchange (ETDEWEB)

    Moore, R.K.G. [Cardiothoracic Centre, Liverpool (United Kingdom)]. E-mail: moore@roger.go-legend.net; Sampson, C. [Cardiothoracic Centre, Liverpool (United Kingdom); MacDonald, S. [Cardiothoracic Centre, Liverpool (United Kingdom); Moynahan, C. [Cardiothoracic Centre, Liverpool (United Kingdom); Groves, D. [National Refractory Angina Centre, Liverpool (United Kingdom); Chester, M.R. [National Refractory Angina Centre, Liverpool (United Kingdom)

    2005-09-01

    AIM: To compare the value of multislice computerized tomography (MSCT) in imaging coronary artery bypass grafts (CABGs) by direct quantitative comparison with standard invasive angiography. METHODS: Using MSCT, 50 consecutive patients who had previously undergone CABG surgery and had recently undergone invasive angiography for recurrent angina pectoris, were studied further using MSCT after intravenous injection of non-ionic contrast agent; cardiac imaging was performed during a single breath-hold. Graft anatomy was quantified, using both quantitative coronary angiography (QCA) and MSCT, by different investigators blinded to each other. Reproducibility was quantified using the standard error of the measurement expressed as a percentage in log-transformed values (CV%) and intraclass correlation (ICC). RESULTS: All 150 grafts were imaged using MSCT; only 4 patent grafts were not imaged using selective angiography. Good agreement was achieved between MSCT and QCA on assessment of proximal anastomoses (CV% 25.2, ICC 0.84), mid-vessel luminal diameter (CV% 15.5, ICC 0.91) and aneurysmal dilations (CV% 14.3). Reasonable agreement was reached on assessment of distal anastomoses (CV% 26.7, ICC 0.66) and categorization of distal run-off (ICC 0.73). Good agreement was observed for stenoses of over 50% luminal loss (CV% 8.7, ICC 0.97) but agreement on assessment of less severe lesions was poor (CV% 208.7, ICC 0.51). CONCLUSION: This study demonstrates that CABGs can be quantitatively evaluated using MSCT, and that significant lesions present in all CABG segments can be reliably identified. Agreement between MSCT and QCA for lesions of less than 50% luminal loss was poor.

  17. Real-time QRS detection using integrated variance for ECG gated cardiac MRI

    Directory of Open Access Journals (Sweden)

    Schmidt Marcus

    2016-09-01

    Full Text Available During magnetic resonance imaging (MRI, a patient’s vital signs are required for different purposes. In cardiac MRI (CMR, an electrocardiogram (ECG of the patient is required for triggering the image acquisition process. However, a reliable QRS detection of an ECG signal acquired inside an MRI scanner is a challenging task due to the magnetohydrodynamic (MHD effect which interferes with the ECG. The aim of this work was to develop a reliable QRS detector usable inside the MRI which also fulfills the standards for medical devices (IEC 60601-2-27. Therefore, a novel real-time QRS detector based on integrated variance measurements is presented. The algorithm was trained on ANSI/AAMI EC13 test waveforms and was then applied to two databases with 12-lead ECG signals recorded inside and outside an MRI scanner. Reliable results for both databases were achieved for the ECG signals recorded inside (DBMRI: sensitivity Se = 99.94%, positive predictive value +P = 99.84% and outside (DBInCarT: Se = 99.29%, +P = 99.72% the MRI. Due to the accurate R-peak detection in real-time this can be used for monitoring and triggering in MRI exams.

  18. Evaluation of regional wall motion in myocardial infarction using animation ECG gated cardiac computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Takahiko; Hyodo, Haruo; Hayashi, Terumi; Yamamoto, Hideo; Yagi, Shigeru

    1984-08-01

    Regional wall motion of the left ventricle was evaluated in 21 patients with myocardial infarction using an animation system of gated cardiac computed tomographic (CT) images (animation gated CCT). The results obtained were compared with data by two-dimensional echocardiography (2-DE). 1. Evaluation of the asynergic area by animation gated CCT and 2-DE: Animation gated CCT detected the following specific regions with asynergy established by 2-DE; 10/10 cases (100%) at the anterior wall of the left ventricle, 14/14 cases (100%) at the interventricular septum, and 9/11 cases (81.8%) at the infero-posterior wall. In addition, one false positive case and one negative case were observed at the lateral wall and the apex, respectively. Of 37 instances with asynergic areas established by 2-DE, 21 cases or 89.2% were detected by animation gated CCT; the sensitivity was 91.9%. 2. Evaluation of severity of asynergy by animation gated CCT and 2-DE: The degree of asynergy evaluated by both methods was compared with each other, and the agreement was as follows: 10/10 cases (100%) at the left-ventricular anterior wall, 13/13 cases (100%) at the interventricular septum, and 7/9 cases (77.8%) at the infero-posterior wall. 3. Evaluation of the asynergic area by nonanimation gated CCT and 2-DE: Nonanimation gated CCT detected asynergic areas ascertained by 2-DE at the following areas; 8/10 cases (80%) at the left-ventricular anterior wall, 12/14 cases (85.7%) at the interventricular septum, and 4/11 cases (36.4%) at the infero-posterior wall. The difference between animation and nonanimation gated CCT was statistically significant (p < 0.05). The severity of asynergy could not be evaluated by nonanimation gated CCT. (J.P.N.).

  19. Reproducibility of ECG-gated Ultrasound Diameter Assessment of Small Abdominal Aortic Aneurysms

    DEFF Research Database (Denmark)

    Bredahl, K; Eldrup, N; Meyer, C

    2013-01-01

    No standardised ultrasound procedure to obtain reliable growth estimates for abdominal aortic aneurysms (AAA) is currently available. We investigated the feasibility and reproducibility of a novel approach controlling for a combination of vessel wall delineation and cardiac cycle variation....

  20. Study of axial magnetic effect

    Energy Technology Data Exchange (ETDEWEB)

    Braguta, Victor [IHEP, Protvino, Moscow region, 142284 Russia ITEP, B. Cheremushkinskaya street 25, Moscow, 117218 (Russian Federation); School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Chernodub, M. N. [CNRS, Laboratoire de Mathématiques et Physique Théorique, Université François-Rabelais Tours, Fédération Denis Poisson, Parc de Grandmont, 37200 Tours, France Department of Physics and Astronomy, University of Gent, Krijgslaan 281, S9, B-9000 Gent (Belgium); School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Goy, V. A. [School of Natural Sciences, Far Eastern Federal University, Sukhanova street 8, Vladivostok, 690950 (Russian Federation); Landsteiner, K. [Instituto de Física Teórica UAM/CSIC, C/ Nicolás Cabrera 13-15, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Molochkov, A. V. [School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Ulybyshev, M. [ITEP, B. Cheremushkinskaya street 25, Moscow, 117218 Russia Institute for Theoretical Problems of Microphysics, Moscow State University, Moscow, 119899 (Russian Federation)

    2016-01-22

    The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T{sup 2} behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction.

  1. Dissipative axial inflation

    Science.gov (United States)

    Notari, Alessio; Tywoniuk, Konrad

    2016-12-01

    We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term phi/fγ F ~F, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density ρR, which can lead to inflation without the need of a flat potential. We analyze the system, for momenta k smaller than the cutoff fγ, including the backreaction numerically. We consider the evolution from a given static initial condition and explicitly show that, if fγ is smaller than the field excursion phi0 by about a factor of at least Script O (20), there is a friction effect which turns on before the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of perturbations, scalars and tensors. Such oscillations have a period of 4-5 efolds and an amplitude which is typically less than a few percent and decreases linearly with fγ. We also stress that the curvature perturbation on uniform density slices should be sensitive to slow-roll parameters related to ρR rather than dot phi2/2 and we discuss the existence of friction terms acting on the perturbations, although we postpone a calculation of the power spectrum and of non-gaussianity to future work and we simply define and compute suitable slow roll parameters. Finally we stress that this scenario may be realized in the axion case, if the coupling 1/fγ to U(1) (photons) is much larger than the coupling 1/fG to non-abelian gauge fields (gluons), since the latter sets the range of the potential and therefore the maximal allowed phi0~ fG.

  2. Relativistic RPA in axial symmetry

    CERN Document Server

    Arteaga, D Pena; 10.1103/PhysRevC.77.034317

    2009-01-01

    Covariant density functional theory, in the framework of self-consistent Relativistic Mean Field (RMF) and Relativistic Random Phase approximation (RPA), is for the first time applied to axially deformed nuclei. The fully self-consistent RMF+RRPA equations are posed for the case of axial symmetry and non-linear energy functionals, and solved with the help of a new parallel code. Formal properties of RPA theory are studied and special care is taken in order to validate the proper decoupling of spurious modes and their influence on the physical response. Sample applications to the magnetic and electric dipole transitions in $^{20}$Ne are presented and analyzed.

  3. Axial Current and Noether Charge

    CERN Document Server

    Mahato, Prasanta

    2012-01-01

    A decade ago, a Lagrangian density has been proposed by the author where only the local symmetries of the Lorentz subgroup of (A)ds group is retained. This formalism has been found to produce some results encompassing that of standard Einstein-Hilbert formalism. In the present article, the conserved axial vector matter currents, constructed in some earlier paper, have been found to be a result of Noether's theorem. PACS: 04.20.Fy, 04.20.Cv, 11.40.-q Keywords: Torsion, Axial Current, Noether's Theorem

  4. MRI Scans

    Science.gov (United States)

    Magnetic resonance imaging (MRI) uses a large magnet and radio waves to look at organs and structures inside your body. Health care professionals use MRI scans to diagnose a variety of conditions, from ...

  5. Axially Symmetric, Spatially Homothetic Spacetimes

    CERN Document Server

    Wagh, S M; Wagh, Sanjay M.; Govinder, Keshlan S.

    2002-01-01

    We show that the existence of appropriate spatial homothetic Killing vectors is directly related to the separability of the metric functions for axially symmetric spacetimes. The density profile for such spacetimes is (spatially) arbitrary and admits any equation of state for the matter in the spacetime. When used for studying axisymmetric gravitational collapse, such solutions do not result in a locally naked singularity.

  6. Thermophoresis of Axially Symmetric Bodies

    Science.gov (United States)

    2007-11-02

    Sweden Abstract. Thermophoresis of axially symmetric bodies is investigated to first order in the Knudsen-mimber, Kn. The study is made in the limit...derived. Asymptotic solutions are studied. INTRODUCTION Thermophoresis as a phenomenon has been known for a long time, and several authors have approached

  7. Axial structure of the nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner

    2002-01-01

    We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.

  8. Computerized axial tomography in clinical pediatrics.

    Science.gov (United States)

    McCullough, D C; Kufta, C; Axelbaum, S P; Schellinger, D

    1977-02-01

    Computerized axial tomography (CAT), a noninvasive radiologie method, provides a new dimension in screening and diagnosis of intracranial pathology. Evaluation of 725 scans in infants and children demonstrates that CAT may be performed with negligible risk, although sedation and restraint are essential to the successful performance of studies in children under 6 years of age. CAT is the preferred initial diagnostic method in suspected hydrocephalls and is accurate in the detection and precise localization of brain tumors. The management of hydrocephalus and brain tumors has been significantly altered by the availability of CAT. Few invasive neuroradiologic procedures are required and pneumography is especially curtailed. Serial scanning is the best available method of monitoring ventricular alterations in hydrocephalus, tumor size during radiotherapy or chemotherapy, and postoperative recurrence of benign neoplasms. Complex intracranial anomalies are detectable with computerized tomography, but complete definition of pathology often requires angiography and air studies. Limited clinical experience in detecting neonatal intraventricular hemorrhage suggests that CAT will be a valuable tool for futlre investigations of that problem.

  9. Exploring the utility of axial lumbar MRI for automatic diagnosis of intervertebral disc abnormalities

    Science.gov (United States)

    Ghosh, Subarna; Chaudhary, Vipin; Dhillon, Gurmeet

    2013-03-01

    In this paper, we explore the importance of axial lumbar MRI slices for automatic detection of abnormalities. In the past, only the sagittal views were taken into account for lumbar CAD systems, ignoring the fact that a radiologist scans through the axial slices as well, to confirm the diagnosis and quantify various abnormalities like herniation and stenosis. Hence, we present an automatic diagnosis system from axial slices using CNN(Convolutional Neural Network) for dynamic feature extraction and classification of normal and abnormal lumbar discs. We show 80:81% accuracy (with a specificity of 85:29% and sensitivity of 75:56%) on 86 cases (391 discs) using only an axial slice for each disc, which implies the usefulness of axial views for automatic lumbar abnormality diagnosis in conjunction with sagittal views.

  10. Optimization of axial blowers. Optimierung von Axial-Ventilatoren

    Energy Technology Data Exchange (ETDEWEB)

    Bolte, W.

    1992-08-01

    For the optimum possible design of axial blowers, trials are evaluated in the article, which are based on the grid profile examined by N. Scholz. The computation for the pressure number and the primary degree of efficiency are shown as well as the evaluation of the effect of the Reynolds and mach number on the degree of efficiency and determination of the secondary losses. In a final example, the dimensions of a blower are computed from the data determined during the trials. (orig.).

  11. View of the Axial Field Spectrometer

    CERN Multimedia

    1980-01-01

    The Axial Field Spectrometer, with the vertical uranium/scintillator calorimeter and the central drift chamber retracted for service. One coil of the Open Axial Field Magnet is just visible to the right.

  12. Scan Statistics

    CERN Document Server

    Glaz, Joseph

    2009-01-01

    Suitable for graduate students and researchers in applied probability and statistics, as well as for scientists in biology, computer science, pharmaceutical science and medicine, this title brings together a collection of chapters illustrating the depth and diversity of theory, methods and applications in the area of scan statistics.

  13. [Axial spondyloarthritis and ankylosing spondylitis].

    Science.gov (United States)

    Nordström, Dan; Kauppi, Markku

    2010-01-01

    Current classification criteria for ankylosing spondylitis do not allow diagnosis before radiographic changes are visible in sacroiliacal joints. The the new axial spondyloarthropathy (SpA) criteria include axial SpA without radiographic changes as well as established ankylosing spondylitis, recognizing them as a continuum of the same disease. This is of major importance as the burden of early SpA is comparable to that of later stage disease. Diagnosis relies on inflammatory MRI findings which is the most significant change compared to earlier criteria. Emerging data on the efficacy of tumor necrosis factor (TNF) alpha blocking therapies already in early but also in established disease have given new promising alternatives for treatment of this often very cumbersome disease, that rarely responds to classic DMARDs.

  14. Axial Spondyloarthritis: An Evolving Concept

    Directory of Open Access Journals (Sweden)

    Nelly Ziadé

    2015-07-01

    Full Text Available Axial spondyloarthritis (AxSpA is the prototype of a family of inter-related yet heterogeneous diseases sharing common clinical and genetic manifestations: the spondyloarthritides (SpAs. The condition mainly affects the sacroiliac joints and axial skeleton, and has a clear classification scheme, wider epidemiological data, and distinct therapeutic guidelines when compared with other SpAs. However, the concept of AxSpA has not been immutable over time and has evolved tremendously on many levels over the past decades. This review identifies the evolution of the AxSpA concept at two levels. First, at the level of classification, the old classifications and rationales leading to the current Assessment of SpondyloArthritis international Society (ASAS classification are reviewed, and the advantages and drawbacks are discussed. Second, at the therapeutic level, current and future treatments are described and treatment strategies are discussed.

  15. Dose reduction during CT coronary angiography; La reduction de dose en coroscanographie

    Energy Technology Data Exchange (ETDEWEB)

    Willoteaux, S.; Sibileau, E.; Caroff, J.; Nedelcu, C.; Thouveny, F. [Service de Radiologie, Hopital Larrey, CHU d' Angers, 49 - Angers (France); Abi Kalil, W.; Delepine, S. [Service de Cardiologie, Hopital Larrey, CHU d' Angers, 49 - Angers (France)

    2010-11-15

    Dose delivery during CT coronary angiography with retrospective ECG gating is high especially due to the important slice overlapping. Optimization of the acquisition parameters is necessary to reduce patient exposure. First, the height of the scan field should be limited to the heart. Both kV and mA should be adjusted based on patient morphology. ECG gated exposure modulation with mA reduction during systole, a technique most applicable for patients with slow and regular heart rate, can result in a dose reduction up to 50%. The use of prospective ECG gating can also reduce patient dose. This technique also requires patients with slow and regular heart rate. (authors)

  16. Head CT scan

    Science.gov (United States)

    Brain CT; Cranial CT; CT scan - skull; CT scan - head; CT scan - orbits; CT scan - sinuses; Computed tomography - cranial; CAT scan - brain ... hold your breath for short periods. A complete scan usually take only 30 seconds to a few ...

  17. Golimumab for treatment of axial spondyloarthritis.

    Science.gov (United States)

    Rios Rodriguez, Valeria; Poddubnyy, Denis

    2016-02-01

    Axial spondyloarthritis comprises two forms: nonradiographic (nonradiographic axial spondyloarthritis) and radiographic (better known as ankylosing spondylitis), which are often considered as two stages of one disease. Historically, all currently available TNF-α inhibitors were first investigated in ankylosing spondylitis and later on in nonradiographic axial spondyloarthritis. This year, EMA has granted golimumab approval for the treatment of active nonradiographic axial spondyloarthritis based on the recently published data from the GO-AHEAD study. This article summarizes recent data on efficacy and safety of golimumab in the treatment of ankylosing spondylitis and nonradiographic axial spondyloarthritis.

  18. Reformatted images improve the detection rate of acute traumatic subdural hematomas on brain CT compared with axial images alone.

    Science.gov (United States)

    Amrhein, Timothy J; Mostertz, William; Matheus, Maria Gisele; Maass-Bolles, Genevieve; Sharma, Komal; Collins, Heather R; Kranz, Peter G

    2017-02-01

    Subdural hematomas (SDHs) comprise a significant percentage of missed intracranial hemorrhage on axial brain CT. SDH detection rates could be improved with the addition of reformatted images. Though performed at some centers, the potential additional diagnostic sensitivity of reformatted images has not yet been investigated. The purpose of our study is to determine if the addition of coronal and sagittal reformatted images to an axial brain CT increases the sensitivity and specificity for detection of acute traumatic SDH. We retrospectively reviewed consecutive brain CTs acquired for acute trauma that contained new SDHs. An equivalent number of normal brain CTs served as control. Paired sets of images were created for each case: (1) axial images only ("axial only") and (2) axial, coronal, sagittal images ("reformat added"). Three readers interpreted both the axial only and companion reformat added for each case, separated by 1 month. Reading times and SDH detection rates were compared. One hundred SDH and 100 negative examinations were collected. Sensitivity and specificity for the axial-only scans were 75.7 and 94.3 %, respectively, compared with 88.3 and 98.3 % for reformat added. There was a 24.3 % false negative (missed SDH) rate with axial-only scans versus 11.7 % with reformat added (p = negatives by greater than 50 %. Reformatted images substantially reduce the number of missed SDHs compared with axial images alone.

  19. Axial Globe Length in Congenital Ptosis.

    Science.gov (United States)

    Takahashi, Yasuhiro; Kang, Hyera; Kakizaki, Hirohiko

    2015-01-01

    To compare axial globe length between affected and unaffected sides in patients with unilateral congenital ptosis. This prospective observational study included 37 patients (age range: 7 months to 58 years). The axial globe length, margin reflex distance-1 (MRD-1), and refractive power were measured. The axial globe length difference was calculated by subtracting the axial globe length on the unaffected side from that of the affected side. The relationships among axial globe length differences, MRD-1 on the affected sides, and patient ages were analyzed using multiple regression analysis. No significant differences were found in the axial globe length between sides (P = .677). The axial globe length difference was 0.17 ± 0.30 mm (mean ± standard deviation), and two patients (5.4%), aged 32 to 57 years, showed axial globe length more than 0.67 mm longer (corresponding to a refractive power of 2 diopters) on the affected side compared to the unaffected side. The multiple regression model between axial globe length difference, patient age, and MRD-1 on the affected sides was less appropriate (YAGL = 0.003XAGE-0.048XMRD-1 +0.112; r = 0.338; adjusted r2 = 0.062; P = .127). The cylindrical power was greater on the affected side (P = .046), although the spherical power was not different between sides (P = .657). No significant difference was identified in the axial globe length between sides, and only 5% of non-pediatric patients showed an axial globe length more than 0.67 mm longer on the affected side. Congenital ptosis may have little effect on axial globe length elongation, and the risk of axial myopia-induced anisometropic amblyopia may be low in patients with unilateral congenital ptosis. Copyright 2015, SLACK Incorporated.

  20. Axial Vector $Z'$ and Anomaly Cancellation

    CERN Document Server

    Ismail, Ahmed; Tsao, Kuo-Hsing; Unwin, James

    2016-01-01

    Whilst the prospect of new $Z'$ gauge bosons with only axial couplings to the Standard Model (SM) fermions is widely discussed, examples of anomaly-free renormalisable models are lacking in the literature. We look to remedy this by constructing several motivated examples. Specifically, we consider axial vectors which couple universally to all SM fermions, as well as those which are generation-specific, leptophilic, and leptophobic. Anomaly cancellation typically requires the presence of new coloured and charged chiral fermions, and we argue that the masses of these new states must generally be comparable to that of the axial vector. Finally, an axial vector mediator could provide a portal between SM and hidden sector states, and we also consider the possibility that the axial vector couples to dark matter. If the dark matter relic density is set due to freeze-out via the axial vector, this strongly constrains the parameter space.

  1. Axial vector Z‧ and anomaly cancellation

    Science.gov (United States)

    Ismail, Ahmed; Keung, Wai-Yee; Tsao, Kuo-Hsing; Unwin, James

    2017-05-01

    Whilst the prospect of new Z‧ gauge bosons with only axial couplings to the Standard Model (SM) fermions is widely discussed, examples of anomaly-free renormalisable models are lacking in the literature. We look to remedy this by constructing several motivated examples. Specifically, we consider axial vectors which couple universally to all SM fermions, as well as those which are generation-specific, leptophilic, and leptophobic. Anomaly cancellation typically requires the presence of new coloured and charged chiral fermions, and we argue that in a large class of models masses of these new states are expected to be comparable to that of the axial vector. Finally, an axial vector mediator could provide a portal between SM and hidden sector states, and we also consider the possibility that the axial vector couples to dark matter. If the dark matter relic density is set due to freeze-out via the axial vector, this strongly constrains the parameter space.

  2. Thyroid Scan and Uptake

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Thyroid Scan and Uptake Thyroid scan and uptake uses ... the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is a ...

  3. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z Thyroid Scan and Uptake Thyroid scan and uptake uses ... the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is a ...

  4. Thyroid Scan and Uptake

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Thyroid Scan and Uptake Thyroid scan and uptake uses small ... Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is a type ...

  5. Diabetes mellitus and the eye: axial length

    OpenAIRE

    Huntjens, B.; O’Donnell, C.

    2006-01-01

    Background and aims: The refractive error of the eye is dependent on its axial length. Refractive error is known to fluctuate significantly in poorly controlled diabetic patients. Recently it has been reported that human eyes fluctuate in axial length during the day. However, this change is not detectable in all subjects, suggesting physiological influences such as diet. The purpose of this study was to investigate fluctuations in axial length and blood glucose levels (BGLs) in diabetic patie...

  6. System Study for Axial Vane Engine Technology

    Science.gov (United States)

    Badley, Patrick R.; Smith, Michael R.; Gould, Cedric O.

    2008-01-01

    The purpose of this engine feasibility study was to determine the benefits that can be achieved by incorporating positive displacement axial vane compression and expansion stages into high bypass turbofan engines. These positive-displacement stages would replace some or all of the conventional compressor and turbine stages in the turbine engine, but not the fan. The study considered combustion occurring internal to an axial vane component (i.e., Diesel engine replacing the standard turbine engine combustor, burner, and turbine); and external continuous flow combustion with an axial vane compressor and an axial vane turbine replacing conventional compressor and turbine systems.

  7. Unsteady Flows in Axial Turbomachines

    Science.gov (United States)

    Marble, F. E.; Rannie, W. D.

    1957-01-01

    Of the various unsteady flows that occur in axial turbomachines certain asymmetric disturbances, of wave length large in comparison with blade spacing, have become understood to a certain extent. These disturbances divide themselves into two categories: self-induced oscillations and force disturbances. A special type of propagating stall appears as a self-induced disturbance; an asymmetric velocity profile introduced at the compressor inlet constitutes a forced disturbance. Both phenomena have been treated from a unified theoretical point of view in which the asymmetric disturbances are linearized and the blade characteristics are assumed quasi-steady. Experimental results are in essential agreement with this theory wherever the limitations of the theory are satisfied. For the self-induced disturbances and the more interesting examples of the forced disturbances, the dominant blade characteristic is the dependence of total pressure loss, rather than the turning angle, upon the local blade inlet angle.

  8. The Emergence of Axial Parts

    Directory of Open Access Journals (Sweden)

    Peter Svenonius

    2007-01-01

    Full Text Available Many languages have specialized locative words or morphemes translating roughly into words like ‘front,’ ‘back,’ ‘top,’ ‘bottom,’ ‘side,’ and so on. Often, these words are used instead of more specialized adpositions to express spatial meanings corresponding to ‘behind,’ ‘above,’ and so on. I argue, on the basis of a cross-linguistic survey of such expressions, that in many cases they motivate a syntactic category which is distinct from both N and P, which I call AxPart for ‘Axial Part’; I show how the category relates to the words which instantiate it, and how the meaning of the construction is derived from the combination of P[lace] elements, AxParts, and the lexical material which expresses them.

  9. Imaging features suggestive of a conjoined nerve root on routine axial MRI

    Energy Technology Data Exchange (ETDEWEB)

    Song, Su Jin; Lee, Joon Woo; Kang, Heung Sik [Seoul National University Bundang Hospital, Department of Radiology, Gyeongi-do (Korea); Choi, Ja-Young; Hong, Sung Hwan; Kim, Na Ra [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea); Kim, Ki-Jeong; Chung, Sang-Ki; Kim, Hyun-Jib [Seoul National University Bundang Hospital, Department of Neurosurgery, Gyeongi-Do (Korea)

    2008-02-15

    The purpose of our study is to evaluate imaging features suggestive of a conjoined nerve root on routine axial MRI. Two radiologists and two surgeons retrospectively reviewed the MRI of three cases in which a conjoined nerve root was discovered during operation and found three suggestive signs on routine axial MR images: ''corner'' (asymmetric morphology of the anterolateral corner of the dural sac), ''fat crescent'' (intervening extradural fat between the asymmetric dura and the nerve root), and ''parallel'' signs (visualization of the entire parallel course of the nerve root at the disc level). Two radiologists prospectively found these signs during routine MRI interpretation sessions over a period of 6 months. If one or a combination of signs were noted on axial MR images, contiguous axial scans were additionally obtained. Three cases that were previously found during operations were also included. Prevalence and confidence scores for each sign were assessed on axial T1- and T2-weighted images. Twelve patients showed one or a combination of the three signs, 9 had contiguous axial MR scans. Five cases were confirmed by operation. The prevalence of the corner, fat crescent, and parallel signs were 12 out of 12 (100%), 6 out of 12 (50%), and 8 out of 12 (67.7%) on axial T1-weighted images. The overall diagnostic confidence was higher on T1- than on T2-weighted images (P < 0.05). On routine axial L-spine MRI, corner, fat crescent, and parallel signs are suggestive of and assist in the recognition of a conjoined nerve root. (orig.)

  10. Axial length in eyes with bilateral pediatric cataract at tertiary eye care center in Nepal: a preliminary report.

    Science.gov (United States)

    Shrestha, U D; Shrestha, M K

    2011-03-01

    The aim of the study was to determine the average axial length reading of the bilateral pediatric cataract undergoing cataract surgery. Pre-operative axial length measurement was done in 80 children below 15 years who had bilateral pediatric cataract. Axial length measurement was done in 56 fellow eyes. The axial length was measured under general anesthesia with the Accutome A-scan. The mean age was 69.7 months (SD=52.6), range from one month to 168 months. The mean axial length reading was 21.3 mm in operated eyes and 21.1 mm in fellow eyes. The range of axial length reading was 16.2 -31.5 mm in operated eyes and it was 16.5 -31.5 mm in fellow eyes. This short observation found that in bilateral pediatric cataract, the axial length value is similar in both operated and fellow eyes. Based on the axial length value of the operated eye, the patients with bilateral congenital cataract can undergo surgery in those eye hospitals where facilities of measurement of axial length is not available.

  11. Helix Scan: A Scan Design for Diagnosis

    Institute of Scientific and Technical Information of China (English)

    WANG Fei; HU Yu; LI Xiaowei

    2007-01-01

    Scan design is a widely used design-for-testability technique to improve test quality and efficiency. For the scan-designed circuit, test and diagnosis of the scan chain and the circuit is an important process for silicon debug and yield learning. However, conventional scan designs and diagnosis methods abort the subsequent diagnosis process after diagnosing the scan chain if the scan chain is faulty. In this work, we propose a design-for-diagnosis scan strategy called helix scan and a diagnosis algorithm to address this issue. Unlike previous proposed methods, helix scan has the capability to carry on the diagnosis process without losing information when the scan chain is faulty. What is more, it simplifies scan chain diagnosis and achieves high diagnostic resolution as well as accuracy. Experimental results demonstrate the effectiveness of our design.

  12. Health and imaging outcomes in axial spondyloarthritis

    NARCIS (Netherlands)

    Machado, P.M.

    2016-01-01

    This thesis focuses on the assessment and monitoring of health and imaging outcomes in axial spondyloarthritis (SpA) and the relationship between these outcomes. Four major contributions to the understanding and management of axial SpA were made: 1) the improvement and facilitation of the assessment

  13. Universal Axial Fluctuations in Optical Tweezers

    CERN Document Server

    Ribezzi-Crivellari, Marco; Ritort, Felix

    2015-01-01

    Optical tweezers allow the measurement of fluctuations at the nano-scale, in particular fluctuations in the end-to-end distance in single molecules. Fluctuation spectra can yield valuable information, but they can easily be contaminated by instrumental effects. We identify axial fluctuations, i.e. fluctuations of the trapped beads in the direction of light propagation, as one of these instrumental effects. Remarkably, axial fluctuations occur on a characteristic timescale similar to that of conformational (folding) transitions, which may lead to misinterpretation of the experimental results. We show that a precise measurement of the effect of force on both axial and conformational fluctuations is crucial to disentangle them. Our results on axial fluctuations are captured by a simple and general formula valid for all optical tweezers setups and provide experimentalists with a general strategy to distinguish axial fluctuations from conformational transitions.

  14. Novel Integration Radial and Axial Magnetic Bearing

    Science.gov (United States)

    Blumenstock, Kenneth; Brown, Gary

    2000-01-01

    Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics; separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and magnetic field modeling results will be presented.

  15. Novel Integrated Radial and Axial Magnetic Bearing

    Science.gov (United States)

    Blumenstock, Kenneth A.; Brown, Gary L.; Powers, Edward I. (Technical Monitor)

    2000-01-01

    Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics, separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and analysis results will be presented.

  16. Axial force measurement for esophageal function testing

    Institute of Scientific and Technical Information of China (English)

    Flemming H Gravesen; Peter Funch-Jensen; Hans Gregersen; Asbjφrn Mohr Drewes

    2009-01-01

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.

  17. Axial force measurement for esophageal function testing.

    Science.gov (United States)

    Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr

    2009-01-14

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.

  18. Analysis and calibration of stage axial vibration for synchrotron radiation nanoscale computed tomography.

    Science.gov (United States)

    Fu, Jian; Li, Chen; Liu, Zhenzhong

    2015-10-01

    Synchrotron radiation nanoscale computed tomography (SR nano-CT) is a powerful analysis tool and can be used to perform chemical identification, mapping, or speciation of carbon and other elements together with X-ray fluorescence and X-ray absorption near edge structure (XANES) imaging. In practical applications, there are often challenges for SR nano-CT due to the misaligned geometry caused by the sample stage axial vibration. It occurs quite frequently because of experimental constraints from the mechanical error of manufacturing and assembly and the thermal expansion during the time-consuming scanning. The axial vibration will lead to the structure overlap among neighboring layers and degrade imaging results by imposing artifacts into the nano-CT images. It becomes worse for samples with complicated axial structure. In this work, we analyze the influence of axial vibration on nano-CT image by partial derivative. Then, an axial vibration calibration method for SR nano-CT is developed and investigated. It is based on the cross correlation of plane integral curves of the sample at different view angles. This work comprises a numerical study of the method and its experimental verification using a dataset measured with the full-field transmission X-ray microscope nano-CT setup at the beamline 4W1A of the Beijing Synchrotron Radiation Facility. The results demonstrate that the presented method can handle the stage axial vibration. It can work for random axial vibration and needs neither calibration phantom nor additional calibration scanning. It will be helpful for the development and application of synchrotron radiation nano-CT systems.

  19. New Anomaly of the Axial-Vector Current

    Institute of Scientific and Technical Information of China (English)

    HE Han-Xin

    2001-01-01

    By computing the axial-vector current operator equation, we find the anomalous axial-vector curl equation besides the well-known anomalous axial-vector divergence equation (the Adler-Bell-Jackiw anomaly) and discuss its implication.``

  20. Axial force measurement for esophageal function testing

    DEFF Research Database (Denmark)

    Gravesen, Flemming Holbæk; Funch-Jensen, Peter; Gregersen, Hans

    2009-01-01

    force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been...... force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external...... documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe...

  1. Axial Super-resolution Evanescent Wave Tomography

    CERN Document Server

    Pendharker, Sarang; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin

    2016-01-01

    Optical tomographic reconstruction of a 3D nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography (AxSET) method that enables the use of regular evanescent wave microscopes like Total Internal Reflection Fluorescence Microscope (TIRF) beyond surface imaging, and achieve tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of three-dimensional fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by 1D (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axi...

  2. How to diagnose axial spondyloarthritis early

    OpenAIRE

    Rudwaleit, M.; van der Heijde, D.; Khan, M.; Braun, J.; Sieper, J.

    2004-01-01

    Background: Chronic low back pain (LBP), the leading symptom of ankylosing spondylitis (AS) and undifferentiated axial spondyloarthritis (SpA), precedes the development of radiographic sacroiliitis, sometimes by many years.

  3. Axial thermal rotation of slender rods.

    Science.gov (United States)

    Li, Dichuan; Fakhri, Nikta; Pasquali, Matteo; Biswal, Sibani Lisa

    2011-05-06

    Axial rotational diffusion of rodlike polymers is important in processes such as microtubule filament sliding and flagella beating. By imaging the motion of small kinks along the backbone of chains of DNA-linked colloids, we produce a direct and systematic measurement of axial rotational diffusivity of rods both in bulk solution and near a wall. The measured diffusivities decrease linearly with the chain length, irrespective of the distance from a wall, in agreement with slender-body hydrodynamics theory. Moreover, the presence of small kinks does not affect the chain's axial diffusivity. Our system and measurements provide insights into fundamental axial diffusion processes of slender objects, which encompass a wide range of entities including biological filaments and linear polymer chains.

  4. Interrupted aortic arch diagnosed by ECG-gated multi-slice computed tomography angiography: a case report

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yang-yang; HAN Ping; FENG Gan-sheng; LIANG Bo

    2005-01-01

    @@ Interrupted aortic arch (IAA) is a rare congenital cardiovascular disease with major intracardiac defects and always with multisystem non-cardiac malformations. It occurs in 1: 10,000 births, and about 1% of the patients with congenital heart defects.

  5. Prospective ECG triggering reduces prosthetic heart valve-induced artefacts compared with retrospective ECG gating on 256-slice CT.

    NARCIS (Netherlands)

    Symersky, P.; Habets, J.; Westers, P.; Mol, B.A. de; Prokop, M.; Budde, R.P.

    2012-01-01

    OBJECTIVES: Multidetector computed tomography (MDCT) has diagnostic value for the evaluation of prosthetic heart valve (PHV) dysfunction but it is hampered by artefacts. We hypothesised that image acquisition using prospective triggering instead of retrospective gating would reduce artefacts related

  6. Prospective ECG triggering reduces prosthetic heart valve-induced artefacts compared with retrospective ECG gating on 256-slice CT

    Energy Technology Data Exchange (ETDEWEB)

    Symersky, Petr [Academic Medical Center, Department of Cardiothoracic Surgery, Amsterdam (Netherlands); Habets, Jesse; Budde, Ricardo P.J. [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Westers, Paul [University Medical Center Utrecht, Department of Biostatistics, Julius Center for Health Sciences and Primary Care, Utrecht (Netherlands); Mol, Bas A.J.M. de [Academic Medical Center, Department of Cardiothoracic Surgery, Amsterdam (Netherlands); University of Technology Eindhoven, Department of Biomedical Engineering, Eindhoven (Netherlands); Prokop, Mathias [Radboud University Nijmegen Medical Center, Department of Radiology, Nijmegen (Netherlands)

    2012-06-15

    Multidetector computed tomography (MDCT) has diagnostic value for the evaluation of prosthetic heart valve (PHV) dysfunction but it is hampered by artefacts. We hypothesised that image acquisition using prospective triggering instead of retrospective gating would reduce artefacts related to pulsating PHV. In a pulsatile in vitro model, a mono- and bileaflet PHV were imaged using 256 MDCT at 60, 75 and 90 beats per minute (BPM) with either retrospective gating (120 kV, 600 mAs, pitch 0.2, CTDI{sub vol} 39.8 mGy) or prospective triggering (120 kV, 200 mAs, CTDI{sub vol} 13.3 mGy). Two thresholds (>175 and <-45HU), derived from the density of surrounding structures, were used for quantification of hyper- and hypodense artefacts. Image noise and artefacts were compared between protocols. Prospective triggering reduced hyperdense artefacts for both valves at every BPM (P = 0.001 all comparisons). Hypodense artefacts were reduced for the monoleaflet valve at 60 (P = 0.009), 75 (P = 0.016) and 90 BPM (P = 0.001), and for the bileaflet valves at 60 (P = 0.001), 90 (P = 0.001) but not at 75 BPM (P = 0.6). Prospective triggering reduced image noise at 60 (P = 0.001) and 75 (P < 0.03) but not at 90 BPM. Compared with retrospective gating, prospective triggering reduced most artefacts related to pulsating PHV in vitro. circle Computed tomographic images are often degraded by prosthetic heart valve-induced artefacts circle Prospective triggering reduces prosthetic heart valve-induced artefacts in vitro circle Artefact reduction at 90 beats per minute occurs without image noise reduction circle Prospective triggering may improve CT image quality of moving hyperdense structures. (orig.)

  7. Nonperturbative Aspects of Axial Vector Vertex

    Institute of Scientific and Technical Information of China (English)

    ZONG Hong-Shi; CHEN Xiang-Song; WANG Fan; CHANG Chao-Hsi; ZHAO En-Guang

    2002-01-01

    It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.

  8. Numerical simulation of axial flow compressors.

    OpenAIRE

    Jesuino Takachi Tomita

    2002-01-01

    This work deals with the numerical simulation of axial flow compressors, from design to performance prediction. The stage performance prediction uses the meanline flow properties. Stage-stacking is used to analyse a multi-stage compressor. A computer program, written in FORTRAN, was developed and is able to design an axial flow compressor given air mass flow, total pressure ratio, overall efficiency and design speed. All geometrical data relevant to the compressor performance prediction is ca...

  9. Wave propagation in axially moving periodic strings

    Science.gov (United States)

    Sorokin, Vladislav S.; Thomsen, Jon Juel

    2017-04-01

    The paper deals with analytically studying transverse waves propagation in an axially moving string with periodically modulated cross section. The structure effectively models various relevant technological systems, e.g. belts, thread lines, band saws, etc., and, in particular, roller chain drives for diesel engines by capturing both their spatial periodicity and axial motion. The Method of Varying Amplitudes is employed in the analysis. It is shown that the compound wave traveling in the axially moving periodic string comprises many components with different frequencies and wavenumbers. This is in contrast to non-moving periodic structures, for which all components of the corresponding compound wave feature the same frequency. Due to this "multi-frequency" character of the wave motion, the conventional notion of frequency band-gaps appears to be not applicable for the moving periodic strings. Thus, for such structures, by frequency band-gaps it is proposed to understand frequency ranges in which the primary component of the compound wave attenuates. Such frequency band-gaps can be present for a moving periodic string, but only if its axial velocity is lower than the transverse wave speed, and, the higher the axial velocity, the narrower the frequency band-gaps. The revealed effects could be of potential importance for applications, e.g. they indicate that due to spatial inhomogeneity, oscillations of axially moving periodic chains always involve a multitude of frequencies.

  10. An Unbroken Axial Vector Current Conservation Law

    CERN Document Server

    Sharafiddinov, Rasulkhozha S

    2015-01-01

    The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space i...

  11. Diagnosis of pituitary microadenomas by CT scan

    Energy Technology Data Exchange (ETDEWEB)

    Sakoda, K.; Gen, M.; Yonezawa, M.; Ohta, M.; Matsumura, S. (Hiroshima Univ. (Japan). School of Medicine)

    1981-10-01

    The presence of pituitary microadenomas can be established by the detection of minor changes on polytomograms of the sella turcica. However, as this method is a procedure for detecting secondary changes due to adenoma, it is understandable that microadenomas which fail to present secondary changes cannot be picked up. From this point of view, we investigated the possibility detecting changes in the pituitary itself by means of CT. An axial scan of pituitary microadenomas by EMI-1010 showed that some of the PRL secreting adenomas and all of the GH secreting adenomas showed areas of high density, and that some of PRL secreting adenomas and all the ACTH secreting adenomas showed areas of low density at the site of the adenomas. On a coronal scan with GE/X2, the normal pituitary is highly enhanced, and an absorption coefficient of 70 - 80 is demonstrated, but on an axial scan the coefficient becomes 25 - 35 due to the partial-volume effect. On a coronal scan pituitary microadenomas are shown as hypodense-lucent or isodense as a normal pituitary. However, the absorption coefficient of the hypodense-lucent area was 50 - 60; this is not low, but is, rather, a high density. At present, it is our belief that it is most effective to use a coronal angle with a high-resolution scanner in the diagnosis of pituitary microadenomas.

  12. Lung gallium scan

    Science.gov (United States)

    Gallium 67 lung scan; Lung scan; Gallium scan - lung; Scan - lung ... Gallium is injected into a vein. The scan will be taken 6 to 24 hours after the gallium is injected. (Test time depends on whether your condition is acute or chronic .) ...

  13. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... limitations of the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan ... tissues in your body. top of page How is the procedure performed? Nuclear medicine imaging is usually ...

  14. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... of the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is ... code: Phone no: Thank you! Do you have a personal story about radiology? Share your patient story ...

  15. Heart PET scan

    Science.gov (United States)

    ... nuclear medicine scan; Heart positron emission tomography; Myocardial PET scan ... A PET scan requires a small amount of radioactive material (tracer). This tracer is given through a vein (IV), ...

  16. Scan BIST with biased scan test signals

    Institute of Scientific and Technical Information of China (English)

    XIANG Dong; CHEN MingJing; SUN JiaGuang

    2008-01-01

    The conventional test-per-scan built-in self-test (BIST) scheme needs a number of shift cycles followed by one capture cycle.Fault effects received by the scan flip-flops are shifted out while shifting in the next test vector like scan testing.Unlike deterministic testing,it is unnecessary to apply a complete test vector to the scan chains.A new scan-based BIST scheme is proposed by properly controlling the test signals of the scan chains,Different biased random values are assigned to the test signals of scan flip-flops in separate scan chains.Capture cycles can be inserted at any clock cycle if necessary.A new testability estimation procedure according to the proposed testing scheme is presented.A greedy procedure is proposed to select a weight for each scan chain.Experimental results show that the proposed method can improve test effectiveness of scan-based BIST greatly,and most circuits can obtain complete fault coverage or very close to complete fault coverage.

  17. Optimization of residual heat removal pump axial thrust and axial bearing

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, F.

    1996-12-01

    The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.

  18. Reducing axial mixing in flotation columns

    Energy Technology Data Exchange (ETDEWEB)

    Al Taweel, A.M.; Ramadan, A.M. [Technical Univ. of Nova Scotia, Halifax (Canada). Chemical Engineering Dept.; Moharam, M.R.; Hassan, T.A. [Al Azhar Univ., Cairo (Egypt); El Mofty, S.M. [Cairo Univ., Giza (Egypt)

    1995-10-01

    The axial mixing characteristics of a pilot-scale flotation column were investigated with the objective of identifying means to mitigate the extent of axial mixing that adversely affects its grade/recovery performance. A wide range of design and operating conditions wa investigated and the experimental results, obtained using the dynamic response method, were analyzed using three axial mixing models. The dynamic response of the column can best be described using the axial dispersion model. The results obtained suggest that the value of the axial dispersion coefficient, E{sub L}, can be significantly reduced by judicial selection of hydrodynamic conditions and/or the use of column inserts that suppress the onset of hydrodynamic instabilities inherent to the operation of conventional flotation columns. Up to 40% reduction in the value of E{sub L} was thus obtained by using spargers that produce more uniform bubble sizes, while up to 30% reductions were obtained by controlling the residual frother concentration. 33 refs., 7 figs.

  19. Axial super-resolution evanescent wave tomography.

    Science.gov (United States)

    Pendharker, Sarang; Shende, Swapnali; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin

    2016-12-01

    Optical tomographic reconstruction of a three-dimensional (3D) nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography method that enables the use of regular evanescent wave microscopes like the total internal reflection fluorescence microscope beyond surface imaging and achieve a tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of 3D fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by one-dimensional (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axial resolution of ∼130  nm. Our method does not require any additional optical components or sample preparation. The proposed method can be combined with focal plane super-resolution techniques like stochastic optical reconstruction microscopy and can also be adapted for THz and microwave near-field tomography.

  20. Axial super-resolution evanescent wave tomography

    Science.gov (United States)

    Pendharker, Sarang; Shende, Swapnali; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin

    2016-12-01

    Optical tomographic reconstruction of a 3D nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography (AxSET) method that enables the use of regular evanescent wave microscopes like Total Internal Reflection Fluorescence Microscope (TIRF) beyond surface imaging, and achieve tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of three-dimensional fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by 1D (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axial resolution of $\\sim$130 nm. Our method does not require any additional optical components or sample preparation. The proposed method can be combined with focal plane super-resolution techniques like STORM and can also be adapted for THz and microwave near-field tomography.

  1. Axial displacement of external and internal implant-abutment connection evaluated by linear mixed model analysis.

    Science.gov (United States)

    Seol, Hyon-Woo; Heo, Seong-Joo; Koak, Jai-Young; Kim, Seong-Kyun; Kim, Shin-Koo

    2015-01-01

    To analyze the axial displacement of external and internal implant-abutment connection after cyclic loading. Three groups of external abutments (Ext group), an internal tapered one-piece-type abutment (Int-1 group), and an internal tapered two-piece-type abutment (Int-2 group) were prepared. Cyclic loading was applied to implant-abutment assemblies at 150 N with a frequency of 3 Hz. The amount of axial displacement, the Periotest values (PTVs), and the removal torque values(RTVs) were measured. Both a repeated measures analysis of variance and pattern analysis based on the linear mixed model were used for statistical analysis. Scanning electron microscopy (SEM) was used to evaluate the surface of the implant-abutment connection. The mean axial displacements after 1,000,000 cycles were 0.6 μm in the Ext group, 3.7 μm in the Int-1 group, and 9.0 μm in the Int-2 group. Pattern analysis revealed a breakpoint at 171 cycles. The Ext group showed no declining pattern, and the Int-1 group showed no declining pattern after the breakpoint (171 cycles). However, the Int-2 group experienced continuous axial displacement. After cyclic loading, the PTV decreased in the Int-2 group, and the RTV decreased in all groups. SEM imaging revealed surface wear in all groups. Axial displacement and surface wear occurred in all groups. The PTVs remained stable, but the RTVs decreased after cyclic loading. Based on linear mixed model analysis, the Ext and Int-1 groups' axial displacements plateaued after little cyclic loading. The Int-2 group's rate of axial displacement slowed after 100,000 cycles.

  2. Elastin Cables Define the Axial Connective Tissue System in the Murine Lung.

    Science.gov (United States)

    Wagner, Willi; Bennett, Robert D; Ackermann, Maximilian; Ysasi, Alexandra B; Belle, Janeil; Valenzuela, Cristian D; Pabst, Andreas; Tsuda, Akira; Konerding, Moritz A; Mentzer, Steven J

    2015-11-01

    The axial connective tissue system is a fiber continuum of the lung that maintains alveolar surface area during changes in lung volume. Although the molecular anatomy of the axial system remains undefined, the fiber continuum of the lung is central to contemporary models of lung micromechanics and alveolar regeneration. To provide a detailed molecular structure of the axial connective tissue system, we examined the extracellular matrix of murine lungs. The lungs were decellularized using a 24 hr detergent treatment protocol. Systematic evaluation of the decellularized lungs demonstrated no residual cellular debris; morphometry demonstrated a mean 39 ± 7% reduction in lung dimensions. Scanning electron microscopy (SEM) demonstrated an intact structural hierarchy within the decellularized lung. Light, fluorescence, and SEM of precision-cut lung slices demonstrated that alveolar duct structure was defined by a cable line element encased in basement membrane. The cable line element arose in the distal airways, passed through septal tips and inserted into neighboring blood vessels and visceral pleura. The ropelike appearance, collagenase resistance and anti-elastin immunostaining indicated that the cable was an elastin macromolecule. Our results indicate that the helical line element of the axial connective tissue system is composed of an elastin cable that not only defines the structure of the alveolar duct, but also integrates the axial connective tissue system into visceral pleura and peripheral blood vessels.

  3. Atlanto-axial infection after acupuncture.

    Science.gov (United States)

    Robinson, A; Lind, C R P; Smith, R J; Kodali, V

    2015-12-11

    A 67-year-old man presented with neck cellulitis following acupuncture for cervical spondylosis. Blood cultures were positive for methicillin-sensitive Staphylococcus aureus. Increased neck pain and bacteraemia prompted MRI, which showed atlanto-axial septic arthritis without signs of infection of the tissues between the superficial cellulitic area and the atlanto-axial joint, thus making direct extension of infection unlikely. It is more likely that haematogenous spread of infection resulted in seeding in the atlanto-axial joint, with the proximity of the arthritis and acupuncture site being coincidental. Acupuncture is a treatment option for some indolent pain conditions. As such, acupuncture services are likely to be more frequently utilised. A history of acupuncture is rarely requested by the admitting doctor and seldom offered voluntarily by the patient, especially where the site of infection due to haematogenous spread is distant from the needling location. Awareness of infectious complications following acupuncture can reduce morbidity through early intervention.

  4. Axial symmetry and conformal Killing vectors

    CERN Document Server

    Mars, M; Mars, Marc; Senovilla, Jose M.M.

    1993-01-01

    Axisymmetric spacetimes with a conformal symmetry are studied and it is shown that, if there is no further conformal symmetry, the axial Killing vector and the conformal Killing vector must commute. As a direct consequence, in conformally stationary and axisymmetric spacetimes, no restriction is made by assuming that the axial symmetry and the conformal timelike symmetry commute. Furthermore, we prove that in axisymmetric spacetimes with another symmetry (such as stationary and axisymmetric or cylindrically symmetric spacetimes) and a conformal symmetry, the commutator of the axial Killing vector with the two others mush vanish or else the symmetry is larger than that originally considered. The results are completely general and do not depend on Einstein's equations or any particular matter content.

  5. Axial flow positive displacement worm gas generator

    Science.gov (United States)

    Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)

    2010-01-01

    An axial flow positive displacement engine has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first, second, and third sections of a core assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first, second, and third twist slopes in the first, second, and third sections respectively. The first twist slopes are less than the second twist slopes and the third twist slopes are less than the second twist slopes. A combustor section extends axially downstream through at least a portion of the second section.

  6. Improving the lattice axial vector current

    Energy Technology Data Exchange (ETDEWEB)

    Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe (Japan); Perlt, H.; Schiller, A. [Leipzig Univ. (Germany). Inst. fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Zanotti, J.M. [Adelaide Univ. (Australia). CSSM, Dept. of Physics

    2015-11-15

    For Wilson and clover fermions traditional formulations of the axial vector current do not respect the continuum Ward identity which relates the divergence of that current to the pseudoscalar density. Here we propose to use a point-split or one-link axial vector current whose divergence exactly satisfies a lattice Ward identity, involving the pseudoscalar density and a number of irrelevant operators. We check in one-loop lattice perturbation theory with SLiNC fermion and gauge plaquette action that this is indeed the case including order O(a) effects. Including these operators the axial Ward identity remains renormalisation invariant. First preliminary results of a nonperturbative check of the Ward identity are also presented.

  7. Organocatalytic atroposelective synthesis of axially chiral styrenes

    Science.gov (United States)

    Zheng, Sheng-Cai; Wu, San; Zhou, Qinghai; Chung, Lung Wa; Ye, Liu; Tan, Bin

    2017-05-01

    Axially chiral compounds are widespread in biologically active compounds and are useful chiral ligands or organocatalysts in asymmetric catalysis. It is well-known that styrenes are one of the most abundant and principal feedstocks and thus represent excellent prospective building blocks for chemical synthesis. Driven by the development of atroposelective synthesis of axially chiral styrene derivatives, we discovered herein the asymmetric organocatalytic approach via direct Michael addition reaction of substituted diones/ketone esters/malononitrile to alkynals. The axially chiral styrene compounds were produced with good chemical yields, enantioselectivities and almost complete E/Z-selectivities through a secondary amine-catalysed iminium activation strategy under mild conditions. Such structural motifs are important precursors for further transformations into biologically active compounds and synthetic useful intermediates and may have potential applications in asymmetric synthesis as olefin ligands or organocatalysts.

  8. Improving the lattice axial vector current

    CERN Document Server

    Horsley, R; Perlt, H; Rakow, P E L; Schierholz, G; Schiller, A; Zanotti, J M

    2015-01-01

    For Wilson and clover fermions traditional formulations of the axial vector current do not respect the continuum Ward identity which relates the divergence of that current to the pseudoscalar density. Here we propose to use a point-split or one-link axial vector current whose divergence exactly satisfies a lattice Ward identity, involving the pseudoscalar density and a number of irrelevant operators. We check in one-loop lattice perturbation theory with SLiNC fermion and gauge plaquette action that this is indeed the case including order $O(a)$ effects. Including these operators the axial Ward identity remains renormalisation invariant. First preliminary results of a nonperturbative check of the Ward identity are also presented.

  9. Axial loaded MRI of the lumbar spine

    Energy Technology Data Exchange (ETDEWEB)

    Saifuddin, A. E-mail: asaifuddin@aol.com; Blease, S.; MacSweeney, E

    2003-09-01

    Magnetic resonance imaging is established as the technique of choice for assessment of degenerative disorders of the lumbar spine. However, it is routinely performed with the patient supine and the hips and knees flexed. The absence of axial loading and lumbar extension results in a maximization of spinal canal dimensions, which may in some cases, result in failure to demonstrate nerve root compression. Attempts have been made to image the lumbar spine in a more physiological state, either by imaging with flexion-extension, in the erect position or by using axial loading. This article reviews the literature relating to the above techniques.

  10. Water Ingestion Into Axial Flow Compressors

    Science.gov (United States)

    1976-08-01

    AFAPL-TR-76-77 WATER INGESTION INTO AXIAL FLOW COMPRESSORS PURDUE UNIVERSITY SCHOOL OF AERONAUTICS AND ASTRONA UTICS S WEST LAFAYETTE, INDIANA 47907...CIPIENT’S CATALOG NUMBER TITL _07" 0 EREO Final i-7 0 Water Ingestion Into Axial Flow Compressorse 1 Auq 75 -: 31 Au0 a6 114o’ H-WPAFB-T-76-l:P ."CO TACT...necessary and Idenify by block number) Water ingestion , turbomachinery, and jet engines. 20 ABSTRACT (Contlinue on tov.ras side Hi necessary and Identify

  11. «FLARES» IN AXIAL SPONDYLOARTHRITIS

    Directory of Open Access Journals (Sweden)

    Sh. F. Erdes

    2016-01-01

    Full Text Available The clear definition of the concept of «flare in axial spondyloarthritis» is of paramount importance for clinical trials and routine practice in particular. It will be able to unify the characteristics of outcomes over a particular period of time on the one hand and to standardize therapeutic approaches on the other. On 4 February 2016, the journal Annals of Rheumatic Diseases published the on-line paper «Preliminary definitions of 'flare' in axial spondyloarthritis, based on pain, BASDAI and ASDAS-CRP: an ASAS initiative» by L. Gossec et al., which was devoted to this topic.

  12. Optimization of Axial Intensity Point Spread Function

    Institute of Scientific and Technical Information of China (English)

    WANG Haifeng; GAN Fuxi; CHEN Zhongyu

    2001-01-01

    It is known that for the converged laser beam, the axial intensity distribution corresponds to a Gaussian curve, that is, the intensity on the focal plane is the peak intensity. When it defocuses, the intensity would decrease rapidly. In optical data storage, for instance, we expect the intensity within a certain distance to be almost equal. In this paper, we propose to use a pure phase superresolution apodizer to optimize the axial intensity distribution of the converged laser beam and at the same time improve the resolution. The intensity point spread function remains almost identical in a wide range within the focal depth.

  13. Axial Nucleon form factors from lattice QCD

    CERN Document Server

    Alexandrou, C; Carbonell, J; Constantinou, M; Harraud, P A; Guichon, P; Jansen, K; Korzec, T; Papinutto, M

    2010-01-01

    We present results on the nucleon axial form factors within lattice QCD using two flavors of degenerate twisted mass fermions. Volume effects are examined using simulations at two volumes of spatial length $L=2.1$ fm and $L=2.8$ fm. Cut-off effects are investigated using three different values of the lattice spacings, namely $a=0.089$ fm, $a=0.070$ fm and $a=0.056$ fm. The nucleon axial charge is obtained in the continuum limit and chirally extrapolated to the physical pion mass enabling comparison with experiment.

  14. Axial Vircator for Electronic Warfare Applications

    Directory of Open Access Journals (Sweden)

    L. Drazan

    2009-12-01

    Full Text Available This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered by magneto-cumulative generator and in weapons for defense of objects (WDO, it is powered by Marx generator. The possible applications of a vircator in the DEWM area are discussed.

  15. Scalar Resonances in Axially Symmetric Spacetimes

    CERN Document Server

    Ranea-Sandoval, Ignacio F

    2015-01-01

    We study properties of resonant solutions to the scalar wave equation in several axially symmetric spacetimes. We prove that non-axial resonant modes do not exist neither in the Lanczos dust cylinder, the $(2+1)$ extreme BTZ spacetime nor in a class of simple rotating wormhole solutions. Moreover, we find unstable solutions to the wave equation in the Lanczos dust cylinder and in the $r^2 <0$ region of the extreme $(2+1)$ BTZ spacetime, two solutions that possess closed timelike curves. Similarities with previous results obtained for the Kerr spacetime are explored.

  16. Nonlinear Optical Properties of Indium Phthalocyanine Axially Grafted Polystyrene Thin Film

    Institute of Scientific and Technical Information of China (English)

    ZHU Rong-Yi; QIU Xue-Qiong; CHEN Yu; QIAN Shi-Xiong

    2006-01-01

    @@ Ultrafast dynamics and third-order nonlinearity of thin films of tert-butyl peripherally-substituted indium ph thalocyanine axially grafted polystyrene (tBu4PcIn-PS) are investigated by femtosecond optical-Kerr-effect (OKE) and z-scan experiments. The fastest component (< 200 fs) in the OKE traces of the film is related to the electron cloud distortion, where the phthalocyanine-polymer interaction may enhance this contribution.

  17. Conventional cerebrospinal fluid scanning

    Energy Technology Data Exchange (ETDEWEB)

    Schicha, H.

    1985-06-01

    Conventional cerebrospinal fluid scanning (CSF scanning) today is mainly carried out in addition to computerized tomography to obtain information about liquor flow kinetics. Especially in patients with communicating obstructive hydrocephalus, CSF scanning is clinically useful for the decision for shunt surgery. In patients with intracranial cysts, CSF scanning can provide information about liquor circulation. Further indications for CSF scanning include the assessment of shunt patency especially in children, as well as the detection and localization of cerebrospinal fluid leaks.

  18. Excitation modes in non-axial nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Leviatan, A.; Ginnochio, J.N.

    1990-01-01

    Excitation modes of non-axial quadrupole shapes are investigated in the framework of interacting boson models. Both {gamma}-unstable and {gamma}-rigid nuclear shapes are considered for systems with one type of boson as well as with proton-neutron bosons. 6 refs.

  19. Cystic lesions accompanying extra-axial tumours

    NARCIS (Netherlands)

    Lohle, PNM; Wurzer, HAL; Seelen, PJ; Kingma, LM; Go, KG

    1999-01-01

    We examined the mechanism of cyst formation in extra-axial tumours in the central nervous system (CNS). Cyst fluid, cerebrospinal fluid (CSF) and blood plasma were analysed in eight patients with nine peritumoral cysts: four with meningiomas, two with intracranial and two spinal intradural schwannom

  20. Knowledge Based Design of Axial Flow Compressor

    Directory of Open Access Journals (Sweden)

    Dinesh kumar.R

    2015-05-01

    Full Text Available In the aerospace industry with highly competitive market the time to design and delivery is shortening every day. Pressure on delivering robust product with cost economy is in demand in each development. Even though technology is older, it is new for each customer requirement and highly non-liner to fit one in another place. Gas turbine is considered one of a complex design in the aircraft system. It involves experts to be grouped with designers of various segments to arrive the best output. The time is crucial to achieve a best design and it needs knowledge automation incorporated with CAD/CAE tools. In the present work an innovative idea in the form of Knowledge Based Engineering for axial compressor is proposed, this includes the fundamental design of axial compressor integrated with artificial intelligence in the form of knowledge capturing and programmed with high level language (Visual Basis.Net and embedded into CATIA v5. This KBE frame work eases out the design and modeling of axial compressor design and produces 3D modeling for further flow simulation with fluid dynamic in Ansys-Fluent. Most of the aerospace components are developed through simulation driven product development and in this case it is established for axial compressor.

  1. Active axial stress in mouse aorta.

    Science.gov (United States)

    Agianniotis, A; Rachev, A; Stergiopulos, N

    2012-07-26

    The study verifies the development of active axial stress in the wall of mouse aorta over a range of physiological loads when the smooth muscle cells are stimulated to contract. The results obtained show that the active axial stress is virtually independent of the magnitude of pressure, but depends predominately on the longitudinal stretch ratio. The dependence is non-monotonic and is similar to the active stress-stretch dependence in the circumferential direction reported in the literature. The expression for the active axial stress fitted to the experimental data shows that the maximum active stress is developed at longitudinal stretch ratio 1.81, and 1.56 is the longitudinal stretch ratio below which the stimulation does not generate active stress. The study shows that the magnitude of active axial stress is smaller than the active circumferential stress. There is need for more experimental investigations on the active response of different types of arteries from different species and pathological conditions. The results of these studies can promote building of refined constrictive models in vascular rheology. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Investigations on Experimental Impellers for Axial Blowers

    Science.gov (United States)

    Encke, W.

    1947-01-01

    A selection of measurements obtained on experimental impellers for axial blowers will be reported. In addition to characteristic curves plotted for low and for high peripheral velocities, proportions and blade sections for six different blower models and remarks on the design of blowers will be presented.

  3. Wave propagation in axially moving periodic strings

    DEFF Research Database (Denmark)

    Sorokin, Vladislav S.; Thomsen, Jon Juel

    2017-01-01

    The paper deals with analytically studying transverse waves propagation in an axially moving string with periodically modulated cross section. The structure effectively models various relevant technological systems, e.g. belts, thread lines, band saws, etc., and, in particular, roller chain drive...

  4. Line scanning, stage scanning confocal microscope (LSSSCM).

    Science.gov (United States)

    Gareau, Daniel S; Krueger, James G; Hawkes, Jason E; Lish, Samantha R; Dietz, Michael P; Mülberger, Alba Guembe; Mu, Euphemia W; Stevenson, Mary L; Lewin, Jesse M; Meehan, Shane A; Carucci, John A

    2017-08-01

    For rapid pathological assessment of large surgical tissue excisions with cellular resolution, we present a line scanning, stage scanning confocal microscope (LSSSCM). LSSSCM uses no scanning mirrors. Laser light is focused with a single cylindrical lens to a line of diffraction-limited width directly into the (Z) sample focal plane, which is parallel to and near the flattened specimen surface. Semi-confocal optical sections are derived from the linear array distribution (Y) and a single mechanical drive that moves the sample parallel to the focal plane and perpendicular to the focused line (X). LSSSCM demonstrates cellular resolution in the conditions of high nuclear density within micronodular basal cell carcinoma.

  5. Might axial myofascial properties and biomechanical mechanisms be relevant to ankylosing spondylitis and axial spondyloarthritis?

    OpenAIRE

    Masi, Alfonse T.

    2014-01-01

    Ankylosing spondylitis and axial spondyloarthropathy have characteristic age- and sex-specific onset patterns, typical entheseal lesions, and marked heritability, but the integrative mechanisms causing the pathophysiological and structural alterations remain largely undefined. Myofascial tissues are integrated in the body into webs and networks which permit transmission of passive and active tensional forces that provide stabilizing support and help to control movements. Axial myofascial hype...

  6. Might axial myofascial properties and biomechanical mechanisms be relevant to ankylosing spondylitis and axial spondyloarthritis?

    OpenAIRE

    Masi, Alfonse T.

    2014-01-01

    Ankylosing spondylitis and axial spondyloarthropathy have characteristic age- and sex-specific onset patterns, typical entheseal lesions, and marked heritability, but the integrative mechanisms causing the pathophysiological and structural alterations remain largely undefined. Myofascial tissues are integrated in the body into webs and networks which permit transmission of passive and active tensional forces that provide stabilizing support and help to control movements. Axial myofascial hype...

  7. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... interfere with the procedure. You will receive specific instructions based on the type of scan you are ... after your nuclear medicine scan. If any special instructions are necessary, you will be informed by a ...

  8. RBC nuclear scan

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003835.htm RBC nuclear scan To use the sharing features on this page, please enable JavaScript. An RBC nuclear scan uses small amounts of radioactive material to ...

  9. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... of the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is ... encourage linking to this site. × Recommend RadiologyInfo to a friend Send to (friend's e-mail address): From ( ...

  10. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... of the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is ... encourage linking to this site. × Recommend RadiologyInfo to a friend Send to (friend's e-mail address): From ( ...

  11. Triple-rule-out dual-source CT angiography of patients with acute chest pain: Dose reduction potential of 100 kV scanning

    Energy Technology Data Exchange (ETDEWEB)

    Krissak, Radko, E-mail: radko.krissak@umm.de [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University (Germany); Henzler, Thomas; Prechel, Anne; Reichert, Miriam [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University (Germany); Gruettner, Joachim; Sueselbeck, Tim [1st Department of Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University (Germany); Schoenberg, Stefan O.; Fink, Christian [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University (Germany)

    2012-12-15

    Purpose: To investigate the dose reduction potential of low kV triple-rule-out dual-source CT angiography (TRO-CTA) in non-obese (BMI ≤ 25 kg/m{sup 2}) patients with acute chest pain. Materials and methods: Sixty consecutive patients were randomly assigned to two different retrospectively ECG-gated TRO-CTA protocols in this prospective trial: Thirty patients were examined with a 120-kV standard protocol (320 reference mAs with automatic tube current modulation, automatically adapted pitch and ECG-pulsing) and served as the control group (group 1), an otherwise identical 100 kV protocol was used in the other thirty patients (group 2) for a radiation dose reduction. Subjective image quality was assessed on a 5 point scale (1: excellent, 5: non-diagnostic) by two blinded observers. Quantitative image analysis assessed vascular attenuation, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in different vascular segments. The effective dose was calculated from the dose length product (DLP) using a conversion coefficient of 0.017 mSv mGy{sup −1} cm{sup −1}. Results: There was no significant difference of age, BMI, heart rate, pitch or scan length between both patient groups. Subjective image quality was rated similar in both groups (group 1: 1.2 ± 0.4, group 2: average score = 1.3 ± 0.5). Vessel attenuation was significantly higher in group 2 than in group 1 (ascending aorta: 456 ± 83 HU vs. 370 ± 78 HU, p < 0.001; pulmonary artery: 468 ± 118 HU vs. 411 ± 91 HU, p = 0.03; left coronary artery: 437 ± 110 HU vs. 348 ± 89 HU, p < 0.001), however, there was no significant difference in SNR (13.2 ± 7.6 vs. 14.5 ± 7.5, p = 0.49) or CNR (13.8 ± 6.6 vs. 15.9 ± 7.7, p = 0.25). The effective radiation dose of the 100 kV protocol was significantly lower (9.6 ± 3.2 mSv vs. 18.1 ± 9.4 mSv, p < 0.0001). Conclusion: TRO-CTA with 100 kV is feasible in non-obese patients and results in diagnostic image quality and significantly reduced radiation dose.

  12. Pulmonary ventilation/perfusion scan

    Science.gov (United States)

    V/Q scan; Ventilation/perfusion scan; Lung ventilation/perfusion scan ... A pulmonary ventilation/perfusion scan is actually two tests. They may be done separately or together. During the perfusion scan, a health care provider injects ...

  13. Multipinhole SPECT helical scan parameters and imaging volume

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Rutao, E-mail: rutaoyao@buffalo.edu; Deng, Xiao [Department of Nuclear Medicine, State University of New York at Buffalo, Buffalo, New York 14214 (United States); Wei, Qingyang; Dai, Tiantian; Ma, Tianyu [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Lecomte, Roger [Department of Nuclear Medicine and Radiobiology, Sherbrooke Molecular Imaging Center, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4 (Canada)

    2015-11-15

    Purpose: The authors developed SPECT imaging capability on an animal PET scanner using a multiple-pinhole collimator and step-and-shoot helical data acquisition protocols. The objective of this work was to determine the preferred helical scan parameters, i.e., the angular and axial step sizes, and the imaging volume, that provide optimal imaging performance. Methods: The authors studied nine helical scan protocols formed by permuting three rotational and three axial step sizes. These step sizes were chosen around the reference values analytically calculated from the estimated spatial resolution of the SPECT system and the Nyquist sampling theorem. The nine helical protocols were evaluated by two figures-of-merit: the sampling completeness percentage (SCP) and the root-mean-square (RMS) resolution. SCP was an analytically calculated numerical index based on projection sampling. RMS resolution was derived from the reconstructed images of a sphere-grid phantom. Results: The RMS resolution results show that (1) the start and end pinhole planes of the helical scheme determine the axial extent of the effective field of view (EFOV), and (2) the diameter of the transverse EFOV is adequately calculated from the geometry of the pinhole opening, since the peripheral region beyond EFOV would introduce projection multiplexing and consequent effects. The RMS resolution results of the nine helical scan schemes show optimal resolution is achieved when the axial step size is the half, and the angular step size is about twice the corresponding values derived from the Nyquist theorem. The SCP results agree in general with that of RMS resolution but are less critical in assessing the effects of helical parameters and EFOV. Conclusions: The authors quantitatively validated the effective FOV of multiple pinhole helical scan protocols and proposed a simple method to calculate optimal helical scan parameters.

  14. Evaluation of reformatted sagittal CT images for measurement of condylar position. Comparison between original axial and coronal images

    Energy Technology Data Exchange (ETDEWEB)

    Hiruma, Takayoshi; Funato, Masahiko; Suganuma, Takeshi; Shinya, Akiyuki; Furuya, Ryoichi; Kawawa, Tadaharu; Seki, Kenji; Okano, Tomohiro [Showa Univ., Tokyo (Japan). School of Dentistry

    1995-09-01

    Accurate measurement of the condylar position is important for diagnosis and treatment of temporomandibular joint dysfunction. Conventional radiographic techniques have been used for this purpose and the recent advance of computed tomography (CT) is applicable to temporomandibular joints. The accuracy of CT in the measurement of the condylar position is still unclear. The purpose of this study was to evaluate the measurement accuracy of the condylar position on reformatted sagittal CT images. Six TMJs obtained from dried skulls were used. The TMJs were examined using a CT scanner with 1 mm thickness/interval in the axial and coronal directions. The visibility of the condyle and fossa on the reformatted sagittal images created were evaluated by measuring the joint space defined in our study. The results were as follows: (1) The superior surface of the condyle and the deepest part of the fossa were obscured in the reformatted images created from the axial scan and coronal scan projected at 60deg to the F-H plane. (2) The reformatted images from the coronal scan projected at 90deg, 80deg or 70deg to the F-H plane clearly depicted the condyle and fossa, the reproducibility of the measurement on these images mentioned above was less than 0.1 mm. The results indicated that the coronal scan from 90deg to 70deg to the F-H plane is more accurate than the axial scan for determining the condylar position on the reformatted sagittal images. (author).

  15. Direct optical nanoscopy with axially localized detection

    CERN Document Server

    Bourg, N; Dupuis, G; Barroca, T; Bon, P; Lécart, S; Fort, E; Lévêque-Fort, S

    2014-01-01

    Evanescent light excitation is widely used in super-resolution fluorescence microscopy to confine light and reduce background noise. Herein we propose a method of exploiting evanescent light in the context of emission. When a fluorophore is located in close proximity to a medium with a higher refractive index, its near-field component is converted into light that propagates beyond the critical angle. This so-called Supercritical Angle Fluorescence (SAF) can be captured using a hig-NA objective and used to determine the axial position of the fluorophore with nanometer precision. We introduce a new technique for 3D nanoscopy that combines direct STochastic Optical Reconstruction Microscopy (dSTORM) imaging with dedicated detection of SAF emission. We demonstrate that our approach of a Direct Optical Nanoscopy with Axially Localized Detection (DONALD) yields a typical isotropic 3D localization precision of 20 nm.

  16. Axial flow positive displacement worm compressor

    Science.gov (United States)

    Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)

    2010-01-01

    An axial flow positive displacement compressor has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first and second sections of a compressor assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first and second twist slopes in the first and second sections respectively. The first twist slopes are less than the second twist slopes. An engine including the compressor has in downstream serial flow relationship from the compressor a combustor and a high pressure turbine drivingly connected to the compressor by a high pressure shaft.

  17. Matrix calculus for axially symmetric polarized beam.

    Science.gov (United States)

    Matsuo, Shigeki

    2011-06-20

    The Jones calculus is a well known method for analyzing the polarization of a fully polarized beam. It deals with a beam having spatially homogeneous polarization. In recent years, axially symmetric polarized beams, where the polarization is not homogeneous in its cross section, have attracted great interest. In the present article, we show the formula for the rotation of beams and optical elements on the angularly variant term-added Jones calculus, which is required for analyzing axially symmetric beams. In addition, we introduce an extension of the Jones calculus: use of the polar coordinate basis. With this calculus, the representation of some angularly variant beams and optical elements are simplified and become intuitive. We show definitions, examples, and conversion formulas between different notations.

  18. Consistent formulation of the spacelike axial gauge

    Energy Technology Data Exchange (ETDEWEB)

    Burnel, A.; Van der Rest-Jaspers, M.

    1983-12-15

    The usual formulation of the spacelike axial gauge is afflicted with the difficulty that the metric is indefinite while no ghost is involved. We solve this difficulty by introducing a ghost whose elimination is such that the metric becomes positive for physical states. The technique consists in the replacement of the gauge condition nxA = 0 by the weaker one partial/sub 0/nxAroughly-equal0.

  19. Transonic Axial Splittered Rotor Tandem Stator Stage

    Science.gov (United States)

    2016-12-01

    compressor rotor was designed incorporating a splitter vane between the principal blades . Historical experiments conducted by Dr. Arthur J...conventional rotor design . The stage is composed of the rotor and stator. The flow of the air passing through the rotor is turned, and the flow is required...derived results achieved the best blade geometry for design continuation. The best circumferential and axial placement for the splitter blade was

  20. Multimode interaction in axially excited cylindrical shells

    OpenAIRE

    2014-01-01

    Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural fr...

  1. Axial flux permanent magnet brushless machines

    CERN Document Server

    Gieras, Jacek F; Kamper, Maarten J

    2008-01-01

    Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators

  2. Enhancement of Optical Coherence Tomography Axial Resolution by Spectral Shaping

    Institute of Scientific and Technical Information of China (English)

    孙汕; 郭继华; 高湔松; 薛平

    2002-01-01

    We propose a new method of changing the spectrum shape to improve the axial resolution of optical coherencetomography (OCT). Theoretical analysis shows that certain spectral shaping can shorten the coherence length.Comparisons of the simulation and experimental measurements of spectral shape and axial resolution of OCTare given, showing that the axial resolution of OCT is enhanced by a factor of 1.4.

  3. Direct optical nanoscopy with axially localized detection

    Science.gov (United States)

    Bourg, N.; Mayet, C.; Dupuis, G.; Barroca, T.; Bon, P.; Lécart, S.; Fort, E.; Lévêque-Fort, S.

    2015-09-01

    Evanescent light excitation is widely used in super-resolution fluorescence microscopy to confine light and reduce background noise. Here, we propose a method of exploiting evanescent light in the context of emission. When a fluorophore is located in close proximity to a medium with a higher refractive index, its near-field component is converted into light that propagates beyond the critical angle. This so-called supercritical-angle fluorescence can be captured using a high-numerical-aperture objective and used to determine the axial position of the fluorophore with nanometre precision. We introduce a new technique for three-dimensional nanoscopy that combines direct stochastic optical reconstruction microscopy (dSTORM) with dedicated detection of supercritical-angle fluorescence emission. We demonstrate that our approach of direct optical nanoscopy with axially localized detection (DONALD) typically yields an isotropic three-dimensional localization precision of 20 nm within an axial range of ∼150 nm above the coverslip.

  4. Axial gravity, massless fermions and trace anomalies

    Science.gov (United States)

    Bonora, L.; Cvitan, M.; Prester, P. Dominis; Pereira, A. Duarte; Giaccari, S.; Štemberga, T.

    2017-08-01

    This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones.

  5. Bessel beam CARS of axially structured samples

    Science.gov (United States)

    Heuke, Sandro; Zheng, Juanjuan; Akimov, Denis; Heintzmann, Rainer; Schmitt, Michael; Popp, Jürgen

    2015-01-01

    We report about a Bessel beam CARS approach for axial profiling of multi-layer structures. This study presents an experimental implementation for the generation of CARS by Bessel beam excitation using only passive optical elements. Furthermore, an analytical expression is provided describing the generated anti-Stokes field by a homogeneous sample. Based on the concept of coherent transfer functions, the underling resolving power of axially structured geometries is investigated. It is found that through the non-linearity of the CARS process in combination with the folded illumination geometry continuous phase-matching is achieved starting from homogeneous samples up to spatial sample frequencies at twice of the pumping electric field wave. The experimental and analytical findings are modeled by the implementation of the Debye Integral and scalar Green function approach. Finally, the goal of reconstructing an axially layered sample is demonstrated on the basis of the numerically simulated modulus and phase of the anti-Stokes far-field radiation pattern. PMID:26046671

  6. Golimumab for the treatment of axial spondyloarthritis.

    Science.gov (United States)

    Gelfer, Gita; Perry, Lisa; Deodhar, Atul

    2016-01-01

    Axial spondyloarthritis (axSpA) is a chronic, immune-mediated inflammatory disease of the axial skeleton that includes ankylosing spondylitis (AS) and non-radiographic axial spondyloarthritis (nr-axSpA). Patients with AS experience chronic pain due to sacroiliac joint and spinal inflammation, and may develop spinal ankylosing with syndesmophyte formation. Tumor necrosis factor α inhibitors (TNFi) have shown promise in the management of AS and axSpA by targeting the underlying inflammatory process, and providing symptomatic relief. Whether they alter the progression of the disease is uncertain. Golimumab is a fully human IgG1 monoclonal antibody that targets and downregulates the pro-inflammatory cytokine TNF-α. The use of golimumab has been shown to reduce the signs and symptoms of axSpA as well as improve patient function and quality reported outcomes. This review focuses on the biological rationale and the results of clinical trials with golimumab for the treatment of axSpA.

  7. Dynamic control of knee axial deformities

    Directory of Open Access Journals (Sweden)

    E. E. Malyshev

    2013-01-01

    Full Text Available The authors have evaluated the clinical examination of the patients with axial malalignments in the knee by the original method and device which was named varovalgometer. The measurements were conducted by tension of the cord through the spina iliaca anterior superior and the middle of the lower pole of patella. The deviation of the center of the ankle estimated by metal ruler which was positioned perpendicular to the lower leg axis on the level of the ankle joint line. The results of comparison of our method and computer navigation in 53 patients during the TKA show no statistically significant varieties but they differ by average 5° of valgus in clinical examination in comparison with mechanical axis which was identified by computer navigation. The dynamic control of axial malalignment can be used in clinical practice for estimation of the results of treatment of pathology with axial deformities in the knee; for the control of reduction and secondary displacement of the fractures around the knee; for assessment of instability; in planning of correctional osteotomies and intraoperative control of deformity correction; for estimation of Q angle in subluxation and recurrent dislocation of patella; in planning of TKA; during the growth of child it allows to assess the progression of deformity.

  8. Normative segment-specific axial and coronal angulation corridors of subaxial cervical column in axial rotation.

    Science.gov (United States)

    Yoganandan, Narayan; Stemper, Brian D; Pintar, Frank A; Baisden, Jamie L; Shender, Barry S; Paskoff, Glenn

    2008-03-01

    In contrast to clinical studies wherein loading magnitudes are indeterminate, experiments permit controlled and quantifiable moment applications, record kinematics in multiple planes, and allow derivation of moment-angulation corridors. Axial and coronal moment-angulation corridors were determined at every level of the subaxial cervical spine, expressed as logarithmic functions, and level-specificity of range of motion and neutral zones were evaluated. segmental primary axial and coupled coronal motions do not vary by level. Although it is known that cervical spine responses are coupled, segment-specific corridors of axial and coronal kinematics under axial twisting moments from healthy normal spines are not reported. Ten human cadaver columns (23-44 years, mean: 34 +/- 6.8) were fixed at the ends and targets were inserted to each vertebra to obtain kinematics in axial and coronal planes. The columns were subjected to pure axial twisting moments. Range of motion and neutral zone for primary-axial and coupled-coronal rotation components were determined at each spinal level. Data were analyzed using factorial analysis of variance. Moment-rotation angulations were expressed using logarithmic functions, and mean +/-1 standard deviation corridors were derived at each level for both components. Moment-angulations responses were nonlinear. Each segmental curve for both components was well represented by a logarithmic function (r2 > 0.95). Factorial analysis of variance indicated that the biomechanical metrics are spinal level-specific (P specific responses. The presentation of moment-angulation corridors for both metrics forms a dataset for the normal population. These segment-specific nonlinear corridors may help clinicians assess dysfunction or instability. These data will assist mathematical models of the spine in improved validation and lead to efficacious design of stabilizing systems.

  9. The Effect of Gestational Age on Axial Length of the Eyes of Premature Infants

    Directory of Open Access Journals (Sweden)

    Mehmet Ali Sekeroglu

    2016-01-01

    Full Text Available Aim: The aim of the present study is to evaluate the axial length of the eyes of premature infants without retinopathy of prematurity and to document the relationship with gestational age and changes as infants grew-up. Material and Method: The axial length of the eyes were measured by using a mobile A-scan ultrasonographic biometry device just before the first retinopathy of prematurity screening examination and 4-weeks thereafter. Results: One-hundred and thirty-six infants with a mean gestational age of 31,7±2,7 weeks and a birth-weight of 1561.0±379.3 g were included in the study. Axial length measurements were done at a mean postconceptional age of 35.8 ±2.6 (31-40 and 39.8±2.7 (35-44 weeks, consecutively. The mean axial length at first and second visits were 16.43±0.42 mm (15.28-17.13 and 16.69±0.41 mm (15.60-17.70, consecutively (p

  10. Prefabrication of axial vascularized tissue engineering coral bone by an arteriovenous loop: A better model

    Energy Technology Data Exchange (ETDEWEB)

    Dong Qingshan [Department of Oral and Maxillofacial Surgery, Wuhan General Hospital of Guangzhou Military Command, Wuhan 430070 (China); Shang Hongtao; Wu Wei [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Chen Fulin [Lab of Tissue Engineering, Faculty of Life Science, Northwest University, Xi' an 710069 (China); Zhang Junrui [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Guo Jiaping [Department of Oral and Maxillofacial Surgery, Wuhan General Hospital of Guangzhou Military Command, Wuhan 430070 (China); Mao Tianqiu, E-mail: tianqiumao@126.com [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China)

    2012-08-01

    The most important problem for the survival of thick 3-dimensional tissues is the lack of vascularization in the context of bone tissue engineering. In this study, a modified arteriovenous loop (AVL) was developed to prefabricate an axial vascularized tissue engineering coral bone in rabbit, with comparison of the arteriovenous bundle (AVB) model. An arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. It was placed in a circular side groove of the coral block. The complex was wrapped with an expanded-polytetrafluoroethylene membrane and implanted beneath inguinal skin. After 2, 4, 6 and 8 weeks, the degree of vascularization was evaluated by India ink perfusion, histological examination, vascular casts, and scanning electron microscopy images of vascular endangium. Newly formed fibrous tissues and vasculature extended over the surfaces and invaded the interspaces of entire coral block. The new blood vessels robustly sprouted from the AVL. Those invaginated cavities in the vascular endangium from scanning electron microscopy indicated vessel's sprouted pores. Above indexes in AVL model are all superior to that in AVB model, indicating that the modified AVL model could more effectively develop vascularization in larger tissue engineering bone. - Highlights: Black-Right-Pointing-Pointer A modified arteriovenous loop (AVL) model in rabbit was developed in this study. Black-Right-Pointing-Pointer Axial prevascularization was induced in a larger coral block by using the AVL. Black-Right-Pointing-Pointer The prefabrication of axial vascularized coral bone is superior as vascular carrier.

  11. Might axial myofascial properties and biomechanical mechanisms be relevant to ankylosing spondylitis and axial spondyloarthritis?

    Science.gov (United States)

    Masi, Alfonse T

    2014-01-01

    Ankylosing spondylitis and axial spondyloarthropathy have characteristic age- and sex-specific onset patterns, typical entheseal lesions, and marked heritability, but the integrative mechanisms causing the pathophysiological and structural alterations remain largely undefined. Myofascial tissues are integrated in the body into webs and networks which permit transmission of passive and active tensional forces that provide stabilizing support and help to control movements. Axial myofascial hypertonicity was hypothesized as a potential excessive polymorphic trait which could contribute to chronic biomechanical overloading and exaggerated stresses at entheseal sites. Such a mechanism may help to integrate many of the characteristic host, pathological, and structural features of ankylosing spondylitis and axial spondyloarthritis. Biomechanical stress and strain were recently documented to correlate with peripheral entheseal inflammation and new bone formation in a murine model of spondyloarthritis. Ankylosing spondylitis has traditionally been classified by the modified New York criteria, which require the presence of definite radiographic sacroiliac joint lesions. New classification criteria for axial spondyloarthritis now include patients who do not fulfill the modified New York criteria. The male-to-female sex ratios clearly differed between the two patient categories - 2:1 or 3:1 in ankylosing spondylitis and 1:1 in non-radiographic axial spondyloarthritis - and this suggests a spectral concept of disease and, among females, milder structural alterations. Magnetic resonance imaging of active and chronic lesions in ankylosing spondylitis and axial spondyloarthritis reveals complex patterns, usually interpreted as inflammatory reactions, but shows similarities to acute degenerative disc disease, which attributed to edema formation following mechanical stresses and micro-damage. A basic question is whether mechanically induced microinjury and immunologically mediated

  12. Effects of Axial Non-uniform Tip Clearances on Aerodynamic Performance of a Transonic Axial Compressor

    Institute of Scientific and Technical Information of China (English)

    Hongwei MA; Baihe LI

    2008-01-01

    This paper presents a numerical investigation of effects of axial non-uniform tip clearances on the aerodynamic performance of a transonic axial compressor rotor (NASA Rotor 37). The three-dimensional steady flow field within the rotor passage was simulated with the datum tip clearance of 0.356 mm at the design wheel speed of 17188.7 rpm. The simulation results are well consistent with the measurement results, which verified the numeri-cal method. Then the three-dimensional steady flow field within the rotor passage was simulated respectively with different axial non-uniform tip clearances. The calculation results showed that optimal axial non-uniform tip clearances could improve the compressor performance, while the efficiency and the pressure ratio of the com-pressor were increased. The flow mechanism is that the axial non-uniform tip clearance can weaken the tip leak-age vortex, blow down low-energy fluids in boundary layers and reduce both flow blockage and tip loss.

  13. Intrinsic carpal ligaments on MR and multidetector CT arthrography: comparison of axial and axial oblique planes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ryan K.L.; Griffith, James F.; Ng, Alex W.H.; Law, Eric K.C. [The Chinese University of Hong Kong, Department of Imaging and Interventional Radiology, Prince Of Wales Hospital, Hong Kong (China); Tse, W.L.; Wong, Clara W.Y.; Ho, P.C. [The Chinese University of Hong Kong, Department of Orthopedics and Traumatology, Prince Of Wales Hospital, Hong Kong (China)

    2017-03-15

    To compare axial and oblique axial planes on MR arthrography (MRA) and multidetector CT arthrography (CTA) to evaluate dorsal and volar parts of scapholunate (SLIL) and lunotriquetral interosseous (LTIL) ligaments. Nine cadaveric wrists of five male subjects were studied. The visibility of dorsal and volar parts of the SLIL and LTIL was graded semi-quantitatively (good, intermediate, poor) on MRA and CTA. The presence of a ligament tear was determined on arthrosocopy and sensitivity, specificity and accuracy of tear detection were calculated. Oblique axial imaging was particularly useful for delineating dorsal and volar parts of the LTIL on MRA with overall 'good' visibility increased from 11 % to 78 %. The accuracy of MRA and CTA in revealing SLIL and LTIL tear was higher using the oblique axial plane. The overall accuracy for detecting SLIL tear on CTA improved from 94 % to 100 % and from 89 % to 94 % on MRA; the overall accuracy of detecting LTIL tear on CTA improved from 89 % to 100 % and from 72 % to 89 % on MRA Oblique axial imaging during CT and MR arthrography improves detection of tears in the dorsal and volar parts of both SLIL and LTIL. (orig.)

  14. Co-axial multicusp source for low axial energy spread ion beam production

    CERN Document Server

    Lee, Y; Leung, K N; Vujic, J L; Williams, M D; Zahir, N

    1999-01-01

    A co-axial multicusp ion source has been designed and tested. This source uses a new magnetic filter configuration. This magnetic filter is efficient in modifying the plasma potential distribution which can reduce the axial energy spread of the extracted ion beam. Energy spreads as low as 0.6 eV have been obtained. The electron temperature in this source has also been found to be about 0.1 eV. Furthermore, the new source configuration is capable of adjusting the radial plasma potential distribution which can improve the transverse ion energy, which results in a low beam emittance. The co-axial source can be used for a number of different applications such as ion projection lithography and radioactive ion beam projects.

  15. Co-axial multicusp source for low axial energy spread ion beam production

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y. E-mail: yylee@lbl.gov; Gough, R.A.; Leung, K.N.; Vujic, J.; Williams, M.D.; Zahir, N

    1999-09-01

    A co-axial multicusp ion source has been designed and tested. This source uses a new magnetic filter configuration. This magnetic filter is efficient in modifying the plasma potential distribution which can reduce the axial energy spread of the extracted ion beam. Energy spreads as low as 0.6 eV have been obtained. The electron temperature in this source has also been found to be about 0.1 eV. Furthermore, the new source configuration is capable of adjusting the radial plasma potential distribution which can improve the transverse ion energy, which results in a low beam emittance. The co-axial source can be used for a number of different applications such as ion projection lithography and radioactive ion beam projects.

  16. Co-axial multicusp source for low axial energy spread ion beam production

    Science.gov (United States)

    Lee, Y.; Gough, R. A.; Leung, K. N.; Vujic, J.; Williams, M. D.; Zahir, N.

    1999-09-01

    A co-axial multicusp ion source has been designed and tested. This source uses a new magnetic filter configuration. This magnetic filter is efficient in modifying the plasma potential distribution which can reduce the axial energy spread of the extracted ion beam. Energy spreads as low as 0.6 eV have been obtained. The electron temperature in this source has also been found to be about 0.1 eV. Furthermore, the new source configuration is capable of adjusting the radial plasma potential distribution which can improve the transverse ion energy, which results in a low beam emittance. The co-axial source can be used for a number of different applications such as ion projection lithography and radioactive ion beam projets.

  17. Axial flow heat exchanger devices and methods for heat transfer using axial flow devices

    Energy Technology Data Exchange (ETDEWEB)

    Koplow, Jeffrey P.

    2016-02-16

    Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.

  18. Radionucleotide scanning in osteomyelitis

    Energy Technology Data Exchange (ETDEWEB)

    Sachs, W.; Kanat, I.O.

    1986-07-01

    Radionucleotide bone scanning can be an excellent adjunct to the standard radiograph and clinical findings in the diagnosis of osteomyelitis. Bone scans have the ability to detect osteomyelitis far in advance of the standard radiograph. The sequential use of technetium and gallium has been useful in differentiating cellulitis and osteomyelitis. Serial scanning with technetium and gallium may be used to monitor the response of osteomyelitis to antibiotic therapy.

  19. Laser Scanning in Forests

    OpenAIRE

    Håkan Olsson; Juha Hyyppä; Markus Holopainen

    2012-01-01

    The introduction of Airborne Laser Scanning (ALS) to forests has been revolutionary during the last decade. This development was facilitated by combining earlier ranging lidar discoveries [1–5], with experience obtained from full-waveform ranging radar [6,7] to new airborne laser scanning systems which had components such as a GNSS receiver (Global Navigation Satellite System), IMU (Inertial Measurement Unit) and a scanning mechanism. Since the first commercial ALS in 1994, new ALS-based fore...

  20. Ultrasonic Transducer Design for the Axial Flaw Detection of Dissimilar Metal Weld

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Byung Sik; Kim, Yong Sik; Yang, Seung Han [Korea Hydro and Nuclear Power Central Research Institute, Daejeon (Korea, Republic of)

    2011-10-15

    Dissimilar metal welds in nuclear power plant are known as very susceptible to PWSCC flaws, and periodically inspected by the qualified inspector and qualified procedure during in-service inspection period. According to field survey data, the majority of their DMWs are located on tapered nozzle or adjacent to a tapered component. These types of configurations restrict examination access and also limit examination volume coverage. Additionally, circumferential scan for axially oriented flaw is very difficult to detect located on tapered surface because the transducer can't receive flaw response from reflector for miss-orientation. To overcome this miss-orientation, it is necessary adapt skewed ultrasonic transducer accommodate tapered surface. The skewed refracted longitudinal ultrasonic transducer designed by modeling and manufactured from the modelling result for axial flaw detection. Experimental results showed that the skewed refracted longitudinal ultrasonic transducer get higher flaw response than non-skewed refracted longitudinal ultrasonic transducer.

  1. Axial Tomography from Digitized Real Time Radiography

    Science.gov (United States)

    Zolnay, A. S.; McDonald, W. M.; Doupont, P. A.; McKinney, R. L.; Lee, M. M.

    1985-01-18

    Axial tomography from digitized real time radiographs provides a useful tool for industrial radiography and tomography. The components of this system are: x-ray source, image intensifier, video camera, video line extractor and digitizer, data storage and reconstruction computers. With this system it is possible to view a two dimensional x-ray image in real time at each angle of rotation and select the tomography plane of interest by choosing which video line to digitize. The digitization of a video line requires less than a second making data acquisition relatively short. Further improvements on this system are planned and initial results are reported.

  2. Ankylosing Spondylitis versus Nonradiographic Axial Spondyloarthritis

    DEFF Research Database (Denmark)

    Glintborg, Bente; Sørensen, Inge J; Østergaard, Mikkel

    2017-01-01

    OBJECTIVE: To compare baseline disease activity and treatment effectiveness in biologic-naive patients with nonradiographic axial spondyloarthritis (nr-axSpA) and ankylosing spondylitis (AS) who initiate tumor necrosis factor inhibitor (TNFi) treatment and to study the role of potential confounders....../disease duration/TNFi-type/smoking/baseline disease activity) on TNFi adherence and response [e.g., Bath Ankylosing Spondylitis Activity Index (BASDAI) 50%/20 mm]. RESULTS: The study included 1250 TNFi-naive patients with axSpA (29% nr-axSpA, 50% AS, 21% lacked radiographs of sacroiliac joints). Patients...

  3. Tunable axial potentials for atom chip waveguides

    CERN Document Server

    Stickney, James A; Imhof, Eric; Kroese, Bethany R; Crow, Jonathon A R; Olson, Spencer E; Squires, Matthew B

    2014-01-01

    We present a method for generating algebraically precise magnetic potentials along the axis of a cold atom waveguide near the surface of an atom chip. With a single chip design consisting of several wire pairs, various axial potentials can be created, including double wells, triple wells, and pure harmonic traps with suppression of higher order terms. We characterize the error along a harmonic trap between the expected algebraic form and magnetic field simulations and find excel- lent agreement, particularly at small displacements from the trap center. Finally, we demonstrate experimental control over the bottom fields of an asymmetric double well potential.

  4. Composite Axial Flow Propulsor for Small Aircraft

    OpenAIRE

    2005-01-01

    This work focuses on the design of an axial flow ducted fan driven by a reciprocating engine. The solution minimizes the turbulization of the flow around the aircraft. The fan has a rotor - stator configuration. Due to the need for low weight of the fan, a carbon/epoxy composite material was chosen for the blades and the driving shaft.The fan is designed for optimal isentropic efficiency and free vortex flow. A stress analysis of the rotor blade was performed using the Finite Element  Method....

  5. Cervical Spine Axial Rotation Goniometer Design

    Directory of Open Access Journals (Sweden)

    Emin Ulaş Erdem

    2012-06-01

    Full Text Available To evaluate the cervical spine rotation movement is quiet harder than other joints. Configuration and arrangement of current goniometers and devices is not always practic in clinics and some methods are quiet expensive. The cervical axial rotation goniometer designed by the authors is consists of five pieces (head apparatus, chair, goniometric platform, eye pads and camera. With this goniometer design a detailed evaluation of cervical spine range of motion can be obtained. Besides, measurement of "joint position sense" which is recently has rising interest in researches can be made practically with this goniometer.

  6. Through-Flow Calculations in Axial Turbomachinery

    Science.gov (United States)

    1976-10-01

    downstzega of the effective throat which is displaced upstream away from its kominal plano flow •_stion. Test data .-n nigh deflection blading tested in...AXIAL PIE ANGs-L;- VrELOC.I- T/Y SI~NG,’ c (,o nd) 2 .959 00 SO~ IS~N1RO iCoWLE tNJ\\\\ NJ\\v ON45l~5INi +U~SWC E.AAINZN5W~N3~6 8Lk5~ P-tO RM~ C -5A

  7. Single Band Helical Antenna in Axial Mode

    Directory of Open Access Journals (Sweden)

    Parminder Singh

    2012-11-01

    Full Text Available Helical antennas have been widely used in a various useful applications, due to their low weight and low profile conformability, easy and cheap realization.Radiation properties of this antenna are examined both theoretically and experimentally. In this paper, an attempt has been made to investigate new helical antenna structure for Applications. CST MWS Software is used for the simulation and design calculations of the helical antennas. The axial ratio, return loss, VSWR, Directivity, gain, radiation pattern is evaluated. Using CST MWS simulation software proposed antenna is designed/simulated and optimized. The antenna exhibits a single band from 0 GHz to 3 GHz for GPS and several satellite applications

  8. Bone scanning in otolaryngology.

    Science.gov (United States)

    Noyek, A M

    1979-09-01

    Modern radionuclide bone scanning has introduced a new concept in physiologic and anatomic diagnostic imaging to general medicine. As otolaryngologists must diagnose and treat disease in relation to the bony and/or cartilaginous supporting structures of the neurocranium and upper airway, this modality should be included in the otolaryngologist's diagnostic armamentarium. It is the purpose of this manuscript to study the specific applications of bone scanning to our specialty at this time, based on clinical experience over the past three years. This thesis describes the development of bone scanning in general (history of nuclear medicine and nuclear physics; history of bone scanning in particular). General concepts in nuclear medicine are then presented; these include a discussion of nuclear semantics, principles of radioactive emmissions, the properties 99mTc as a radionuclide, and the tracer principle. On the basis of these general concepts, specific concepts in bone scanning are then brought forth. The physiology of bone and the action of the bone scan agents is presented. Further discussion considers the availability and production of the bone scan agent, patient factors, the gamma camera, the triphasic bone scan and the ultimate diagnostic principle of the bone scan. Clinical applications of bone scanning in otolaryngology are then presented in three sections. Proven areas of application include the evaluation of malignant tumors of the head and neck, the diagnosis of temporomandibular joint disorders, the diagnosis of facial fractures, the evaluation of osteomyelitis, nuclear medicine imaging of the larynx, and the assessment of systemic disease. Areas of adjunctive or supplementary value are also noted, such as diagnostic imaging of meningioma. Finally, areas of marginal value in the application of bone scanning are described.

  9. Frequency scanning microstrip antennas

    DEFF Research Database (Denmark)

    Danielsen, Magnus; Jørgensen, Rolf

    1979-01-01

    The principles of using radiating microstrip resonators as elements in a frequency scanning antenna array are described. The resonators are cascade-coupled. This gives a scan of the main lobe due to the phase-shift in the resonator in addition to that created by the transmission line phase...

  10. Scanning laser Doppler vibrometry

    DEFF Research Database (Denmark)

    Brøns, Marie; Thomsen, Jon Juel

    With a Scanning Laser Doppler Vibrometer (SLDV) a vibrating surface is automatically scanned over predefined grid points, and data processed for displaying vibration properties like mode shapes, natural frequencies, damping ratios, and operational deflection shapes. Our SLDV – a PSV-500H from...

  11. Axial residual stresses in boron fibers

    Science.gov (United States)

    Behrendt, D. R.

    1978-01-01

    A method of measuring axial residual stresses in boron fibers is presented. With this method, the axial residual stress distribution as a function of radius is determined from the fiber surface to the core including the average residual stress in the core. Such measurements on boron on tungsten (B/W) fibers show that the residual stresses for 102, 142, 203, and 366 micron diam fibers are similar, being compressive at the surface and changing monotonically to a region of tensile stress within the boron. At approximately 25% of the original radius, the stress reaches a maximum tensile stress of about 860 MN sq m and then decreases to a compressive stress near the tungsten boride core. Data are presented for 203-micron diam B/W fibers that show annealing above 900 C reduces the residual stresses. A comparison between 102-micron diam B/W and boron on carbon (B/C) show that the residual stresses are similar in the outer regions of the fibers, but that large differences near and in the core are observed. Fracture of boron fibers is discussed.

  12. Single Rod Vibration in Axial Flow

    Science.gov (United States)

    Weichselbaum, Noah; Wang, Shengfu; Bardet, Philippe

    2013-11-01

    Fluid structure interaction of a single rod in axial flow is a coupled dynamical system present in many application including nuclear reactors, steam generators, and towed antenna arrays. Fluid-structure response can be quantified thanks to detailed experimental data where both structure and fluid responses are recorded. Such datum deepen understanding of the physics inherent to the system and provide high-dimensionality quantitative measurements to validate coupled structural and CFD codes with various level of complexity. In this work, single rods fixed on both ends in a concentric pipe, are subjected to an axial flow with Reynolds number based on hydraulic diameter of Re =4000. Rods of varying material stiffness and diameter are utilized in the experiment resulting in a range of dimensionless U between 0.5 and 1, where U = (ρA/EI)1/2uL. Experimental measurements of the velocity field around the rod are taken with PIV from time-resolved Nd:YLF laser and a high speed CMOS camera. Three-dimensional and temporal vibration and deflection of the rod is recorded with shadowgraphy utilizing two sets of pulsed high power LED and dedicated CMOS camera. Through integration of these two diagnostics, it is possible to reconstruct the full FSI domain providing unique validation data.

  13. Multi-frequency axial transmission bone ultrasonometer.

    Science.gov (United States)

    Tatarinov, Alexey; Egorov, Vladimir; Sarvazyan, Noune; Sarvazyan, Armen

    2014-07-01

    The last decade has seen a surge in the development of axial transmission QUS (Quantitative UltraSound) technologies for the assessment of long bones using various modes of acoustic waves. The condition of cortical bones and the development of osteoporosis are determined by numerous mechanical, micro-structural, and geometrical or macro-structural bone properties like hardness, porosity and cortical thickness. Such complex manifestations of osteoporosis require the evaluation of multiple parameters with different sensitivities to the various properties of bone that are affected by the disease. This objective may be achieved by using a multi-frequency ultrasonic examination The ratio of the acoustic wavelength to the cortical thickness can be changed by varying the frequency of the ultrasonic pulse propagating through the long bone that results in the change in composition of the induced wave comprised of a set of numerous modes of guided, longitudinal, and surface acoustic waves. The multi-frequency axial transmission QUS method developed at Artann Laboratories (Trenton, NJ) is implemented in the Bone Ultrasonic Scanner (BUSS). In the current version of the BUSS, a train of ultrasonic pulses with 60, 100, 400, 800, and 1200 kHz frequencies is used. The developed technology was tested on a variety of bone phantoms simulating normal, osteopenic, and osteoporotic bones. The results of this study confirm the feasibility of the multi-frequency approach for the assessment of the processes leading to osteoporosis.

  14. LIDAR COMBINED SCANNING UNIT

    Directory of Open Access Journals (Sweden)

    V. V. Elizarov

    2016-11-01

    Full Text Available Subject of Research. The results of lidar combined scanning unit development for locating leaks of hydrocarbons are presented The unit enables to perform high-speed scanning of the investigated space in wide and narrow angle fields. Method. Scanning in a wide angular field is produced by one-line scanning path by means of the movable aluminum mirror with a frequency of 20Hz and amplitude of 20 degrees of swing. Narrowband scanning is performed along a spiral path by the deflector. The deflection of the beam is done by rotation of the optical wedges forming part of the deflector at an angle of ±50. The control function of the scanning node is performed by a specialized software product written in C# programming language. Main Results. This scanning unit allows scanning the investigated area at a distance of 50-100 m with spatial resolution at the level of 3 cm. The positioning accuracy of the laser beam in space is 15'. The developed scanning unit gives the possibility to browse the entire investigated area for the time not more than 1 ms at a rotation frequency of each wedge from 50 to 200 Hz. The problem of unambiguous definition of the beam geographical coordinates in space is solved at the software level according to the rotation angles of the mirrors and optical wedges. Lidar system coordinates are determined by means of GPS. Practical Relevance. Development results open the possibility for increasing the spatial resolution of scanning systems of a wide range of lidars and can provide high positioning accuracy of the laser beam in space.

  15. A custom CMOS imager for multi-beam laser scanning microscopy and an improvement of scanning speed

    Science.gov (United States)

    Seo, Min-Woong; Kagawa, Keiichiro; Yasutomi, Keita; Kawahito, Shoji

    2013-02-01

    Multi-beam laser scanning confocal microscopy with a 256 × 256-pixel custom CMOS imager performing focal-plane pinhole effect, in which any rotating disk is not required, is demonstrated. A specimen is illuminated by 32 × 32 diffraction limited light spots whose wavelength and pitch are 532nm and 8.4 μm, respectively. The spot array is generated by a microlens array, which is scanned by two-dimensional piezo actuator according to the scanning of the image sensor. The frame rate of the prototype is 0.17 Hz, which is limited by the actuator. The confocal effect has been confirmed by comparing the axial resolution in the confocal imaging mode with that of the normal imaging mode. The axial resolution in the confocal mode measured by the full width at half maximum (FWHM) for a planar mirror was 8.9 μm, which is showed that the confocality has been achieved with the proposed CMOS image sensor. The focal-plane pinhole effect in the confocal microscopy with the proposed CMOS imager has been demonstrated at low frame rate. An improvement of the scanning speed and a CMOS imager with photo-sensitivity modulation pixels suitable for high-speed scanning are also discussed.

  16. Axial vascularization of a large volume calcium phosphate ceramic bone substitute in the sheep AV loop model.

    Science.gov (United States)

    Beier, Justus P; Horch, Raymund E; Hess, Andreas; Arkudas, Andreas; Heinrich, Johanna; Loew, Johanna; Gulle, Heinz; Polykandriotis, Elias; Bleiziffer, Oliver; Kneser, Ulrich

    2010-03-01

    Vascularization still remains an obstacle to engineering of bone tissue with clinically relevant dimensions. Our aim was to induce axial vascularization in a large volume of a clinically approved biphasic calcium phosphate ceramic by transferring the arteriovenous (AV) loop approach to a large animal model. HA/beta-TCP granula were mixed with fibrin gel for a total volume of 16 cm(3), followed by incorporation into an isolation chamber together with an AV loop. The chambers were implanted into the groins of merino sheep and the development of vascularization was monitored by sequential non-invasive magnetic resonance imaging (MRI). The chambers were explanted after 6 and 12 weeks, the pedicle was perfused with contrast agent and specimens were subjected to micro-computed tomography (micro-CT) scan and histological analysis. Sequential MRI demonstrated a significantly increased perfusion in the HA/beta-TCP matrices over time. Micro-CT scans and histology confirmed successful axial vascularization of HA/beta-TCP constructs. This study demonstrates, for the first time, successful axial vascularization of a clinically approved bone substitute with a significant volume in a large animal model by means of a microsurgically created AV loop, thus paving the way for the first microsurgical transplantation of a tissue-engineered, axially vascularized bone with clinically relevant dimensions.

  17. Laser Scanning in Forests

    Directory of Open Access Journals (Sweden)

    Håkan Olsson

    2012-09-01

    Full Text Available The introduction of Airborne Laser Scanning (ALS to forests has been revolutionary during the last decade. This development was facilitated by combining earlier ranging lidar discoveries [1–5], with experience obtained from full-waveform ranging radar [6,7] to new airborne laser scanning systems which had components such as a GNSS receiver (Global Navigation Satellite System, IMU (Inertial Measurement Unit and a scanning mechanism. Since the first commercial ALS in 1994, new ALS-based forest inventory approaches have been reported feasible for operational activities [8–12]. ALS is currently operationally applied for stand level forest inventories, for example, in Nordic countries. In Finland alone, the adoption of ALS for forest data collection has led to an annual savings of around 20 M€/year, and the work is mainly done by companies instead of governmental organizations. In spite of the long implementation times and there being a limited tradition of making changes in the forest sector, laser scanning was commercially and operationally applied after about only one decade of research. When analyzing high-ranked journal papers from ISI Web of Science, the topic of laser scanning of forests has been the driving force for the whole laser scanning research society over the last decade. Thus, the topic “laser scanning in forests” has provided a significant industrial, societal and scientific impact. [...

  18. Resonant scanning mechanism

    Science.gov (United States)

    Wallace, John; Newman, Mike; Gutierrez, Homero; Hoffman, Charlie; Quakenbush, Tim; Waldeck, Dan; Leone, Christopher; Ostaszewski, Miro

    2014-10-01

    Ball Aerospace & Technologies Corp. developed a Resonant Scanning Mechanism (RSM) capable of combining a 250- Hz resonant scan about one axis with a two-hertz triangular scan about the orthogonal axis. The RSM enables a rapid, high-density scan over a significant field of regard (FOR) while minimizing size, weight, and power requirements. The azimuth scan axis is bearing mounted allowing for 30° of mechanical travel, while the resonant elevation axis is flexure and spring mounted with five degrees of mechanical travel. Pointing-knowledge error during quiescent static pointing at room temperature across the full range is better than 100 μrad RMS per axis. The compact design of the RSM, roughly the size of a soda can, makes it an ideal mechanism for use on low-altitude aircraft and unmanned aerial vehicles. Unique aspects of the opto-mechanical design include i) resonant springs which allow for a high-frequency scan axis with low power consumption; and ii) an independent lower-frequency scan axis allowing for a wide FOR. The pointing control system operates each axis independently and employs i) a position loop for the azimuth axis; and ii) a unique combination of parallel frequency and amplitude control loops for the elevation axis. All control and pointing algorithms are hosted on a 200-MHz microcontroller with 516 KB of RAM on a compact 3"×4" digital controller, also of Ball design.

  19. Study on the Axial Dispersion of Liquid in Column Flotation

    Institute of Scientific and Technical Information of China (English)

    周鵾; 曾爱武; 高长宝; 余国琮

    2003-01-01

    An experimental study on the axial dispersion of liquid was carried out in a 0.382-m-ID flotation column packed with different structured packings or free of packings. The correlations of axial Peclet numbers with the liquid and gas superficial Reynolds numbers were developed for various packings. Among the packings tested, it is found that in the column packed with 250Y or 350Y packings the axial dispersion is the lowest. The addition of frother can decrease the axial dispersion. By the simulation analysis of the one-dimension dispersion model of packed flotation column, it is found that small axial dispersion, high collection rate constant and low axial liquid velocity can increase the collection zone recovery.

  20. Scleral Cross-linking Using Riboflavin and Ultraviolet-A Radiation for Prevention of Axial Myopia in a Rabbit Model.

    Science.gov (United States)

    Dotan, Assaf; Kremer, Israel; Gal-Or, Orly; Livnat, Tami; Zigler, Arie; Bourla, Dan; Weinberger, Dov

    2016-04-03

    Myopic individuals, especially those with severe myopia, are at higher-than-normal risk of cataract, glaucoma, retinal detachment and chorioretinal abnormalities. In addition, pathological myopia is a common irreversible cause of visual impairment and blindness. Our study demonstrates the effect of scleral crosslinking using riboflavin and ultraviolet-A radiation on the development of axial myopia in a rabbit model. The axial length of the eyeball was measured by A-scan ultrasound in New Zealand white rabbits aged 13 days (male and female). The eye then underwent 360° conjunctival peritomy with scleral crosslinking, followed by tarsorrhaphy. Axial elongation was induced in 13 day-old New Zealand rabbits by suturing their right eye eyelids (tarsorrhaphy). The eyes were divided into quadrants, and every quadrant had two scleral irradiation zones, each with an area of 0.2 cm² and a radius of 4 mm. Crosslinking was performed by dropping 0.1% dextran-free riboflavin-5-phosphate onto the irradiation zones 20 sec before ultraviolet-A irradiation and every 20 sec during the 200 sec irradiation time. UVA radiation (370 nm) was applied perpendicular to the sclera at 57 mW/cm² (total UVA light dose, 57 J/cm²). Tarsorrhaphies were removed on day 55, followed by repeated axial length measurements. This study demonstrates that scleral crosslinking with riboflavin and ultraviolet-A radiation effectively prevents occlusion-induced axial elongation in a rabbit model.

  1. CT scan of choristoma

    Energy Technology Data Exchange (ETDEWEB)

    Moriki, A.; Morimoto, M.; Sada, Y.; Kurisaka, M.; Mori, K.

    1987-02-01

    Choristoma is a rare tumor that occurs in the pituitary gland. The case presented here is a 44-year-old male. A plain CT scan demonstrated a slight high-density mass near the posterior clinoid of the sella turcica, while a moderate and homogeneous enhancing effect and a clear borderline were shown by an enhanced CT scan. A cornal CT scan study showed that the tumor extended from the intrasellar to the suprasellar region. The diagnosis of choristoma was made by means of histology.

  2. High-Frequency Axial Fatigue Test Procedures for Spectrum Loading

    Science.gov (United States)

    2016-07-20

    REPORT NO: NAWCADPAX/TIM-2016/49 HIGH - FREQUENCY AXIAL FATIGUE TEST PROCEEDURES FOR SPECTRUM LOADING by David T. Rusk, AIR...OF THE NAVY NAVAL AIR WARFARE CENTER AIRCRAFT DIVISION PATUXENT RIVER, MARYLAND NAWCADPAX/TIM-2016/49 20 July 2016 HIGH - FREQUENCY AXIAL...Technical Information Memorandum 3. DATES COVERED 4. TITLE AND SUBTITLE High - Frequency Axial Fatigue Test Procedures for Spectrum Loading

  3. A technique to determine a desired preparation axial inclination.

    Science.gov (United States)

    Parker, M Harry; Ivanhoe, John R; Blalock, John S; Frazier, Kevin B; Plummer, Kevin D

    2003-10-01

    The guidelines recommended in the literature for the convergence angle of a crown preparation vary from 3 to 24 degrees. There is a lack of guidelines on techniques to achieve a specific axial inclination. The purpose of this article was to present a practical technique, with a diamond rotary cutting instrument of known axial inclination, to determine the diamond rotary cutting instrument angulations required to achieve the desired axial inclination of a preparation.

  4. Design and Test of a Transonic Axial Splittered Rotor

    Science.gov (United States)

    2015-06-15

    AXIAL SPLITTERED ROTOR A new design procedure was developed that uses commercial-off-the-shelf software (MATLAB, SolidWorks , and ANSYS-CFX) for the...TRANSONIC AXIAL SPLITTERED ROTOR Report Title A new design procedure was developed that uses commercial-off-the-shelf software (MATLAB, SolidWorks , and...that uses commercial-off-the-shelf software (MATLAB, SolidWorks , and ANSYS-CFX) for the geometric rendering and analysis of a transonic axial

  5. Rotordynamics of Turbine Labyrinth Seals with Rotor Axial Shifting

    OpenAIRE

    Jinxiang Xi; Rhode, David L.

    2006-01-01

    Rotors in high-performance steam turbines experience a significant axial shifting during starting and stopping processes due to thermal expansion, for example. This axial shifting could significantly alter the flow pattern and the flow-induced rotordynamic forces in labyrinth seals, which in turn, can considerably affect the rotor-seal system performance. This paper investigates the influence of the rotor axial shifting on leakage rate as well as rotordynamic forces in hi...

  6. Axial vector transition form factors of N → Δ in QCD

    Science.gov (United States)

    Kucukarslan, A.; Ozdem, U.; Ozpineci, A.

    2016-12-01

    The isovector axial vector form factors of N → Δ transition are calculated by employing Light-cone QCD sum rules. The analytical results are analyzed by both the conventional method, and also by a Monte Carlo based approach which allows one to scan all of the parameter space. The predictions are also compared with the results in the literature, where available. Although the Monte Carlo analysis predicts large uncertainties in the predicted results, the predictions obtained by the conventional analysis are in good agreement with other results in the literature.

  7. Phospholipid electrospun nanofibers: effect of solvents and co-axial processing on morphology and fiber diameter

    DEFF Research Database (Denmark)

    Jørgensen, Lars; Qvortrup, Klaus; Chronakis, Ioannis S.

    2015-01-01

    Asolectin phospholipid nano-microfibers were prepared using electrospinning processing. The asolectin fibers were studied by scanning electron microscopy, and the fiber morphology was found to be strongly dependent on the phospholipid concentration and the solvents used. The solvents studied were...... does not follow the theoretically predicted value of similar to 0.35 mu m because of the intermolecular aggregation between the reverse micelles formed in the highly concentrated asolectin solutions. However, when co-axial solvent electrospinning was applied, where the outer needle contains a pure...

  8. High-precision efficiency calibration of a high-purity co-axial germanium detector

    Energy Technology Data Exchange (ETDEWEB)

    Blank, B., E-mail: blank@cenbg.in2p3.fr [Centre d' Etudes Nucléaires de Bordeaux Gradignan, UMR 5797, CNRS/IN2P3, Université de Bordeaux, Chemin du Solarium, BP 120, 33175 Gradignan Cedex (France); Souin, J.; Ascher, P.; Audirac, L.; Canchel, G.; Gerbaux, M.; Grévy, S.; Giovinazzo, J.; Guérin, H.; Nieto, T. Kurtukian; Matea, I. [Centre d' Etudes Nucléaires de Bordeaux Gradignan, UMR 5797, CNRS/IN2P3, Université de Bordeaux, Chemin du Solarium, BP 120, 33175 Gradignan Cedex (France); Bouzomita, H.; Delahaye, P.; Grinyer, G.F.; Thomas, J.C. [Grand Accélérateur National d' Ions Lourds, CEA/DSM, CNRS/IN2P3, Bvd Henri Becquerel, BP 55027, F-14076 CAEN Cedex 5 (France)

    2015-03-11

    A high-purity co-axial germanium detector has been calibrated in efficiency to a precision of about 0.15% over a wide energy range. High-precision scans of the detector crystal and γ-ray source measurements have been compared to Monte-Carlo simulations to adjust the dimensions of a detector model. For this purpose, standard calibration sources and short-lived online sources have been used. The resulting efficiency calibration reaches the precision needed e.g. for branching ratio measurements of super-allowed β decays for tests of the weak-interaction standard model.

  9. Modular functional organisation of the axial locomotor system in salamanders.

    Science.gov (United States)

    Cabelguen, Jean-Marie; Charrier, Vanessa; Mathou, Alexia

    2014-02-01

    Most investigations on tetrapod locomotion have been concerned with limb movements. However, there is compelling evidence that the axial musculoskeletal system contributes to important functions during locomotion. Adult salamanders offer a remarkable opportunity to examine these functions because these amphibians use axial undulations to propel themselves in both aquatic and terrestrial environments. In this article, we review the currently available biological data on axial functions during various locomotor modes in salamanders. We also present data showing the modular organisation of the neural networks that generate axial synergies during locomotion. The functional implication of this modular organisation is discussed.

  10. Energy Dissipation in Sandwich Structures During Axial Compression

    DEFF Research Database (Denmark)

    Urban, Jesper

    2002-01-01

    The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full-scale structu......The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full...

  11. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... Uptake? A thyroid scan is a type of nuclear medicine imaging. The radioactive iodine uptake test (RAIU) ... of thyroid function, but does not involve imaging. Nuclear medicine is a branch of medical imaging that ...

  12. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... which are encased in metal and plastic and most often shaped like a box, attached to a ... will I experience during and after the procedure? Most thyroid scan and thyroid uptake procedures are painless. ...

  13. The conical scan radiometer

    Science.gov (United States)

    Prosch, T.; Hennings, D.

    1982-07-01

    A satellite-borne conical scan radiometer (CSR) is proposed, offering multiangular and multispectral measurements of Earth radiation fields, including the total radiances, which are not available from conventional radiometers. Advantages of the CSR for meteorological studies are discussed. In comparison to conventional cross track scanning instruments, the CSR is unique with respect to the selected picture element size which is kept constant by means of a specially shaped detector matrix at all scan angles. The conical scan mode offers the chance to improve angular sampling. Angular sampling gaps of previous satellite-borne radiometers can be interpolated and complemented by CSR data. Radiances are measured through 10 radiometric channels which are selected to study cloudiness, water vapor, ozone, surface albedo, ground and mean stratospheric temperature, and aerosols.

  14. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... scan and uptake uses small amounts of radioactive materials called radiotracers, a special camera and a computer ... last two months that used iodine-based contrast material. Your doctor will instruct you on how to ...

  15. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... of page What are some common uses of the procedure? The thyroid scan is used to determine ... you are undergoing. top of page What does the equipment look like? Special camera or imaging devices ...

  16. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... Uptake? A thyroid scan is a type of nuclear medicine imaging. The radioactive iodine uptake test (RAIU) ... of thyroid function, but does not involve imaging. Nuclear medicine is a branch of medical imaging that ...

  17. Pediatric CT Scans

    Science.gov (United States)

    The Radiation Epidemiology Branch and collaborators have initiated a retrospective cohort study to evaluate the relationship between radiation exposure from CT scans conducted during childhood and adolescence and the subsequent development of cancer.

  18. Shoulder MRI scan

    Science.gov (United States)

    ... finding on an x-ray or bone scan Shoulder pain and fever Decreased motion of the shoulder joint ... of the shoulder joint Shoulder instability Shoulder weakness Shoulder pain and a history of cancer Shoulder pain that ...

  19. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... a computer to provide information about your thyroid’s size, shape, position and function that is often unattainable ... The thyroid scan is used to determine the size, shape and position of the thyroid gland. The ...

  20. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... as an overactive thyroid gland, a condition called hyperthyroidism , cancer or other growths assess the nature of ... an x-ray or CT scan, surgeries or treatments using iodinated contrast material within the last two ...

  1. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... eat for several hours before your exam because eating can affect the accuracy of the uptake measurement. ... often unattainable using other imaging procedures. For many diseases, nuclear medicine scans yield the most useful information ...

  2. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... regulates the rate at which the body converts food to energy. top of page What are some ... often unattainable using other imaging procedures. For many diseases, nuclear medicine scans yield the most useful information ...

  3. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... called hyperthyroidism , cancer or other growths assess the nature of a nodule discovered in the gland detect ... CT scan, surgeries or treatments using iodinated contrast material within the last two months. are taking medications ...

  4. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... are noninvasive and, with the exception of intravenous injections, are usually painless medical tests that help physicians ... before the scan. The radiotracer given by intravenous injection is usually given up to 30 minutes prior ...

  5. Scanning Auger Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — A JEOL model 7830F field emission source, scanning Auger microscope. Specifications / Capabilities: Ultra-high vacuum (UHV), electron gun range from 0.1 kV to 25 kV,...

  6. Photothermal imaging scanning microscopy

    Science.gov (United States)

    Chinn, Diane; Stolz, Christopher J.; Wu, Zhouling; Huber, Robert; Weinzapfel, Carolyn

    2006-07-11

    Photothermal Imaging Scanning Microscopy produces a rapid, thermal-based, non-destructive characterization apparatus. Also, a photothermal characterization method of surface and subsurface features includes micron and nanoscale spatial resolution of meter-sized optical materials.

  7. Scanning Auger Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — A JEOL model 7830F field emission source, scanning Auger microscope.Specifications / Capabilities:Ultra-high vacuum (UHV), electron gun range from 0.1 kV to 25 kV,...

  8. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... A thyroid scan is a type of nuclear medicine imaging. The radioactive iodine uptake test (RAIU) is ... thyroid function, but does not involve imaging. Nuclear medicine is a branch of medical imaging that uses ...

  9. Slow Scan Telemedicine

    Science.gov (United States)

    1984-01-01

    Originally developed under contract for NASA by Ball Bros. Research Corporation for acquiring visual information from lunar and planetary spacecraft, system uses standard closed circuit camera connected to a device called a scan converter, which slows the stream of images to match an audio circuit, such as a telephone line. Transmitted to its destination, the image is reconverted by another scan converter and displayed on a monitor. In addition to assist scans, technique allows transmission of x-rays, nuclear scans, ultrasonic imagery, thermograms, electrocardiograms or live views of patient. Also allows conferencing and consultation among medical centers, general practitioners, specialists and disease control centers. Commercialized by Colorado Video, Inc., major employment is in business and industry for teleconferencing, cable TV news, transmission of scientific/engineering data, security, information retrieval, insurance claim adjustment, instructional programs, and remote viewing of advertising layouts, real estate, construction sites or products.

  10. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... evaluate changes in the gland following medication use, surgery, radiotherapy or chemotherapy top of page How should ... such as an x-ray or CT scan, surgeries or treatments using iodinated contrast material within the ...

  11. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... of page What are some common uses of the procedure? The thyroid scan is used to determine ... you are undergoing. top of page What does the equipment look like? The special camera and imaging ...

  12. Cervical spine CT scan

    Science.gov (United States)

    ... defects of the cervical spine Bone problems Fracture Osteoarthritis Disc herniation Risks Risks of CT scans include: ... Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, ...

  13. Aerodynamic Modelling and Optimization of Axial Fans

    DEFF Research Database (Denmark)

    Sørensen, Dan Nørtoft

    A numerically efficient mathematical model for the aerodynamics oflow speed axial fans of the arbitrary vortex flow type has been developed.The model is based on a blade-element principle, whereby therotor is divided into a number of annular streamtubes.For each of these streamtubes relations...... for velocity, pressure andradial position are derived from the conservationlaws for mass, tangential momentum and energy.The resulting system of equations is non-linear and, dueto mass conservation and pressure equilibrium far downstream of the rotor,strongly coupled.The equations are solved using the Newton...... distributionsof pitch angle and chord length have been chosen as independent variablesin the optimizations.Besides restricting the geometry of the rotor,constraints have been added to ensure a required pressure rise as well asnon-stalled flow conditions.Optimizations have been performed tomaximize the mean value...

  14. The Axial Part Phrase in Japanese

    Directory of Open Access Journals (Sweden)

    Kaori Takamine

    2007-01-01

    Full Text Available In this paper, I investigate the categorial status of spatial terms in locative/directional expressions in Japanese. I will show that a certain class of spatial terms have a distinct categorial status from both regular postpositions and nouns. On one hand, syntactic diagnostics such as doubling, coordination by to, and co-occurrence with demonstratives indicate that these spatial terms belong to a nominal category rather than to a postpositional category. On the other hand, the fact that these spatial terms are modified by range modifiers indicates that they are more similar to regular postpositions than to nouns. On the basis of these diagnostics, I will argue that spatial terms in Japanese need to be assigned a new category Axial Part Phrase which is proposed by Svenonius 2006.

  15. Composite Axial Flow Propulsor for Small Aircraft

    Directory of Open Access Journals (Sweden)

    R. Poul

    2005-01-01

    Full Text Available This work focuses on the design of an axial flow ducted fan driven by a reciprocating engine. The solution minimizes the turbulization of the flow around the aircraft. The fan has a rotor - stator configuration. Due to the need for low weight of the fan, a carbon/epoxy composite material was chosen for the blades and the driving shaft.The fan is designed for optimal isentropic efficiency and free vortex flow. A stress analysis of the rotor blade was performed using the Finite Element  Method. The skin of the blade is calculated as a laminate and the foam core as a solid. A static and dynamic analysis were made. The RTM technology is compared with other technologies and is described in detail. 

  16. Aerodynamics of advanced axial-flow turbomachinery

    Science.gov (United States)

    Serovy, G. K.; Kavanagh, P.; Kiishi, T. H.

    1980-01-01

    A multi-task research program on aerodynamic problems in advanced axial-flow turbomachine configurations was carried out at Iowa State University. The elements of this program were intended to contribute directly to the improvement of compressor, fan, and turbine design methods. Experimental efforts in intra-passage flow pattern measurements, unsteady blade row interaction, and control of secondary flow are included, along with computational work on inviscid-viscous interaction blade passage flow techniques. This final report summarizes the results of this program and indicates directions which might be taken in following up these results in future work. In a separate task a study was made of existing turbomachinery research programs and facilities in universities located in the United States. Some potentially significant research topics are discussed which might be successfully attacked in the university atmosphere.

  17. Casimir Energy in the Axial Gauge

    CERN Document Server

    Esposito, G; Kirsten, K; Esposito, Giampiero; Kamenshchik, Alexander Yu.; Kirsten, Klaus

    2000-01-01

    The zero-point energy of a conducting spherical shell is studied by imposing the axial gauge via path-integral methods, with boundary conditions on the electromagnetic potential and ghost fields. The coupled modes are then found to be the temporal and longitudinal modes for the Maxwell field. The resulting system can be decoupled by studying a fourth-order differential equation with boundary conditions on longitudinal modes and their second derivatives. The exact solution of such equation is found by using a Green-function method, and is obtained from Bessel functions and definite integrals involving Bessel functions. Complete agreement with a previous path-integral analysis in the Lorenz gauge, and with Boyer's value, is proved in detail.

  18. Scanning laser Doppler vibrometry

    OpenAIRE

    2016-01-01

    With a Scanning Laser Doppler Vibrometer (SLDV) a vibrating surface is automatically scanned over predefined grid points, and data processed for displaying vibration properties like mode shapes, natural frequencies, damping ratios, and operational deflection shapes. Our SLDV – a PSV-500H from Polytec Inc. – was acquired and put to operation in October 2014, paid by a sub-donation of DKK 1,5 mill. of the total VILLUM CASMaT grant. Opening possibilities of measuring complicated vibration shapes...

  19. Aerodynamic modelling and optimization of axial fans

    Energy Technology Data Exchange (ETDEWEB)

    Noertoft Soerensen, Dan

    1998-01-01

    A numerically efficient mathematical model for the aerodynamics of low speed axial fans of the arbitrary vortex flow type has been developed. The model is based on a blade-element principle, whereby the rotor is divided into a number of annular stream tubes. For each of these stream tubes relations for velocity, pressure and radial position are derived from the conservation laws for mass, tangential momentum and energy. The equations are solved using the Newton-Raphson methods, and solutions converged to machine accuracy are found at small computing costs. The model has been validated against published measurements on various fan configurations, comprising two rotor-only fan stages, a counter-rotating fan unit and a stator-rotor stator stage. Comparisons of local and integrated properties show that the computed results agree well with the measurements. Optimizations have been performed to maximize the mean value of fan efficiency in a design interval of flow rates, thus designing a fan which operates well over a range of different flow conditions. The optimization scheme was used to investigate the dependence of maximum efficiency on 1: the number of blades, 2: the width of the design interval and 3: the hub radius. The degree of freedom in the choice of design variable and constraints, combined with the design interval concept, provides a valuable design-tool for axial fans. To further investigate the use of design optimization, a model for the vortex shedding noise from the trailing edge of the blades has been incorporated into the optimization scheme. The noise emission from the blades was minimized in a flow rate design point. Optimizations were performed to investigate the dependence of the noise on 1: the number of blades, 2: a constraint imposed on efficiency and 3: the hub radius. The investigations showed, that a significant reduction of noise could be achieved, at the expense of a small reduction in fan efficiency. (EG) 66 refs.

  20. Doses of Coronary Study in 64 Channel Multi-Detector Computed Tomography : Reduced Radiation Dose According to Varity of Examnination Protocols

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Moon Chan [Dept. of Diagnostic Radiology, Samsung Medical Center, Seoul (Korea, Republic of)

    2009-09-15

    To compare radiation dose for coronary CT angiography (CTA) obtained with 6 examination protocols such as a retrospectively ECG gated helical scan, a prospectively ECG gated sequential scan, low kVp technique, and cardiac dose modulation technique. Coronary CTA was performed by using 6 current clinical protocols to evaluate effective dose and organ dose in primary beam area with anthropomorphic female phantom and glass dosimetric system in 64 channel multi-detector CT. After acquiring topograms of frontal and lateral projection with 80 kVp and 10 mA, main coronary scan was done with 0.35 sec tube rotation time, 40 mm collimation (0.625 mm x 64 ea), small scan field of view (32 cm diameter), 105 mm scan length. Heart beat rate of phantom was maintained 60 bpm in ECG gating. In constant mAs technique 120 kVp, 600 mA was used, and 100 kVp for low kVp technique. In a retrospectively ECG gated helical CT technique 0.22 pitch was used, peak mA (600 mA) was adopted in range of 40-80% of R-R interval and 120 mA (80% reduction) in others with cardiac dose modulation. And 210 mAs was used without cardiac dose modulation. In a prospectively ECG gated sequential CT technique data were acquired at 75% R-R interval (middle diastolic phase in cardiac cycle), and 120 msec additional padding of the tube-on time was used. For effective dose calculation region specific conversion factor of dose length product in thorax was used, which was recommended by EUR 16262. The mean effective dose for conventional coronary CTA without cardiac dose modulation in a retrospectively ECG gated helical scan was 17.8 mSv, and mean organ dose of heart was 103.8 mGy. With low kVp and cardiac dose modulation the mean effective dose showed 54.5% reduction, and heart dose showed 52.3% reduction, compared with that of conventional coronary CTA. And at the sequential scan(SnapShot pulse mode) under prospective ECG gating the mean effective dose was 4.9 mSv, this represents an 72.5% reduction compared with

  1. Advanced Network Scanning

    Directory of Open Access Journals (Sweden)

    Ashiqur Rahman

    2016-07-01

    Full Text Available Network scanning is à procedure for identifying active hosts on a network, either for the purpose of attacking them or for network security assessment. Scanning procedures, such as ping sweeps and port scans, return information about which IP addresses map to live hosts that are active on the Internet and what services they offer. Another scanning method, inverse mapping, returns information about what IP addresses do not map to live hosts; this enables an attacker to make assumptions about viable addresses. Scanning is one of three components of intelligence gathering for an attacker. In the foot printing phase, the attacker creates a profile of the target organization, with information such as its domain name system (DNS and e-mail servers, and its IP address range. Most of this information is available online. In the scanning phase, the attacker finds information about the specific IP addresses that can be accessed over the Internet, their operating systems, the system architecture, and the services running on each computer. In the enumeration phase, the attacker gathers information such as network user and group names, routing tables, and Simple Network Management Protocol (SNMP data

  2. Efficacy of axial and tangential corneal topography maps in detecting subclinical keratoconus.

    Science.gov (United States)

    Tummanapalli, Shyam Sunder; Potluri, Haresh; Vaddavalli, Pravin Krishna; Sangwan, Virender S

    2015-10-01

    To investigate and compare the efficacy of axial and tangential corneal topography maps obtained using the Orbscan IIz scanning-slit device to distinguish differences in eyes with subclinical keratoconus from normal eyes. LV Prasad Eye Institute, Hyderabad, India. Retrospective cross-sectional study. Axial and tangential maps of the anterior and posterior corneal surfaces were obtained in eyes of patients with subclinical keratoconus (normal fellow eye of an eye with clinically diagnosed keratoconus). The following measurements were obtained from each map and compared between the 2 groups: location of the corneal apex in millimeters relative to the corneal vertex, dioptric power at the corneal apex and corneal vertex, corneal irregularity indices at 3.0 mm and 5.0 mm, anterior-posterior apex ratio, and inferior-superior dioptric asymmetry value. Maps were obtained in 71 eyes (71 patients) with subclinical keratoconus and 76 normal eyes (76 patients). The tangential posterior apex curvature was significantly steeper than the axial posterior apex curvature in both groups (P keratoconus eyes from normal eyes. The anterior-posterior apex ratio on the tangential map and 5.0 mm irregularity index of the posterior corneal surface were highly sensitive and specific for early detection of subclinical keratoconus. Tangential corneal topography maps should be considered in preoperative subclinical keratoconus screening. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  3. Deformation and failure mechanisms of 18650 battery cells under axial compression

    Science.gov (United States)

    Zhu, Juner; Zhang, Xiaowei; Sahraei, Elham; Wierzbicki, Tomasz

    2016-12-01

    An important deformation mode during ground impacts of battery packs made of cylindrical battery cells is axial compression. This type of loading subjects the cell to a complex deformation pattern and failure mechanism. The design of endcaps plays an important role in such deformations. To explore the sequence of deformation and the underlying failure mechanisms, a combined experimental/numerical study was carried out. Tests were conducted on 18650 cells, and the deformation of each component was carefully investigated and documented. There are four different stages in the force-displacement curve, corresponding with deformation of various components in the endcap assembly. A short circuit happens at a displacement of 4 mm. To clarify these observations, a detailed Finite Element model was set up, covering the geometry and the mechanical property of almost all the components of the cell. Using the simulation results, the sequence of the axial compression was revealed, which was subsequently validated by Micro CT scans as well as analytical solutions. Based on the precise analysis of the mechanical behavior, the cause of the short circuit during axial loading was clarified. Two failure mechanisms in the separator at the top section of the cell explain the possible causes of short circuit.

  4. Volar morphology of the distal radius in axial planes: a quantitative analysis.

    Science.gov (United States)

    Oura, Keiichiro; Oka, Kunihiro; Kawanishi, Yohei; Sugamoto, Kazuomi; Yoshikawa, Hideki; Murase, Tsuyoshi

    2015-04-01

    To investigate the cause of rupture of the flexor pollicis longus (FPL) after volar plate fixation of distal radius fractures, previous studies have examined the shape of the distal radius in the sagittal plane or in the lateral view. However, there are no reports on the anatomical shape of the volar surface concavity of the distal radius in the axial plane. We hypothesized that this concavity might contribute to the mismatch between the plate and the surface of the radius. To test this hypothesis, we constructed three-dimensional models of the radius and FPL based on computed tomography scans of 70 normal forearms. We analyzed axial cross-sectional views with 2 mm intervals. In all cases, the volar surface of the distal radius was concave in the axial plane. The concavity depth was maximum at 6 mm proximal to the palmar edge of the lunate fossa and progressively decreased toward the proximal radius. FPL was closest to the radius at 2 mm proximal to the palmar edge of the lunate fossa. The volar surface of the distal radius was externally rotated from proximal to distal. These results may help to develop new implants which fit better to the radius and decrease tendon irritation.

  5. Dynamic visualization of axial p-n junctions in single gallium nitride nanorods under electrical bias.

    Science.gov (United States)

    Lu, Yu-Jung; Lu, Ming-Yen; Yang, Yu-Chen; Chen, Hung-Ying; Chen, Lih-Juann; Gwo, Shangjr

    2013-09-24

    We demonstrate a direct visualization method based on secondary electron (SE) imaging in scanning electron microscopy for mapping electrostatic potentials across axial semiconductor nanorod p-n junctions. It is found that the SE doping contrast can be directly related to the spatial distribution of electrostatic potential across the axial nanorod p-n junction. In contrast to the conventional SE doping contrast achieved for planar p-n junctions, the quasi-one-dimensional geometry of nanorods allows for high-resolution, versatile SE imaging under high accelerating voltage, long working distance conditions. Furthermore, we are able to delineate the electric field profiles across the axial nanorod p-n junction as well as depletion widths at different reverse biases. By using standard p-n junction theory and secondary ion mass spectroscopy, the carrier concentrations of p- and n-regions can be further extracted from the depletion widths under reverse biasing conditions. This direct imaging method enables determination of electrostatic potential variation of p-n junctions in semiconductor nanorod and nanowire devices with a spatial resolution better than 10 nm.

  6. Computerized axial tomography of the chest for visualization of ''absent'' pulmonary arteries

    Energy Technology Data Exchange (ETDEWEB)

    Sondheimer, H.M. (Upstate Medical Center, Syracuse, NY); Oliphant, M.; Schneider, B.; Kavey, R.E.W.; Blackman, M.S.; Parker, F.B. Jr.

    1982-05-01

    To expand the search for central pulmonary arteries in six patients with absence of cardiac-pulmonary continuity, computerized axial tomography (CAT) of the chest was performed. The CAT scans were compared with previous arteriograms and pulmonary vein wedge angiograms. Three patients with type IV truncus arteriosus were studied, and none had a central, right or left pulmonary artery on CAT scan. However, two patients with tetralogy of Fallot with pulmonary atresia and a patent ductus arteriosus to the right lung demonstrated the presence of a left pulmonary artery. In addition, one child with truncus arteriosus with ''absent'' left pulmonary artery demonstrated a left pulmonary artery on the CAT scan. The CAT scan may therefore enhance our ability to search for disconnected pulmonary arteries in children with complex cyanotic congenital heart disease.

  7. Through flow analysis within axial flow turbomachinery blade rows

    Science.gov (United States)

    Girigoswami, H.

    1986-09-01

    Using Katsanis' Through Flow Code, inviscid flow through an axial flow compressor rotor blade as well as flow through inlet guide vanes are analyzed and the computed parameters such as meridional velocity distribution, axial velocity distribution along radial lines, and velocity distribution over blade surfaces are presented.

  8. Improved axial position detection in optical tweezers measurements

    DEFF Research Database (Denmark)

    Dreyer, Jakob Kisbye; Berg-Sørensen, Kirstine; Oddershede, Lene

    2004-01-01

    We investigate the axial position detection of a trapped microsphere in an optical trap by using a quadrant photodiode. By replacing the photodiode with a CCD camera, we obtain detailed information on the light scattered by the microsphere. The correlation of the interference pattern with the axial...

  9. Testing of Axially Loaded Bucket Foundation with Applied Overburden Pressure

    DEFF Research Database (Denmark)

    Vaitkunaite, Evelina; Ibsen, Lars Bo; Nielsen, Benjaminn Nordahl

    This report analyses laboratory testing data performed with a bucket foundation model subjected to axial loading. The examinations were conducted at the Geotechnical laboratory of Aalborg University. The report aims at showing and discussing the results of the static and cyclic axial loading tests...

  10. Test Setup for Axially Loaded Piles in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina

    The test setup for testing axially static and cyclic loaded piles in sand is described in the following. The purpose for the tests is to examine the tensile capacity of axially loaded piles in dense fully saturated sand. The pile dimensions are chosen to resemble full scale dimension of piles used...... in offshore pile foundations today....

  11. An Unbroken Axial-Vector Current Conservation Law

    Science.gov (United States)

    Sharafiddinov, Rasulkhozha S.

    2016-04-01

    The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space in which a neutrino is characterized by left as well as by right space-time coordinates. Therefore, it is not surprising that whatever the main purposes experiments about a quasielastic axial-vector mass say in favor of an axial-vector mirror Minkowski space-time.

  12. A new approach to radial and axial gauges

    Science.gov (United States)

    Weigert, Heribert; Heinz, Ulrich

    1992-03-01

    We develop a new path integral formulation of QCD in radial and axial gauges. This formalism yields free propagators which are free of gauge poles. We find that radial gauges are ghost free. In axial gauges ghosts cannot generally be excluded from the formalism due to the need to fix the residual gauge freedom.

  13. Confocal Line Scanning Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Chanbai, S; Wiora, G; Wewer, L [NanoFocus AG, Lindnerstr. 98, 46149 Oberhausen (Germany); Zafarullah, I [Applied Scientific Imaging Inc., Toronto (Canada); Roth, H, E-mail: chanbai@nanofocus.de, E-mail: wiora@nanofocus.de [Institute of Automatic Control Engineering, University of Siegen, Hoelderlinstr. 3, 57068 Siegen (Germany)

    2011-08-19

    We have developed a novel confocal-based imaging sensor for surface characterization. In this case, a tilted-plane technique is incorporated in a confocal imaging system to create a new parallel scanning scheme, enabling the sensor to be designed and developed as a robust and simple configuration. With a tilted disk consisting of in-line pinholes, a motionless parallel z scanning scheme is manifested when the specimen is transversely scanned through the stationary diffraction-foci projecting at different depths. This sensor uses a line scanning approach, so that it is entitled as a Confocal Line Scanning Sensor (CLSS). In this paper, the CLSS principle, the concept of data processing, and major calibration are described. The sensor was first developed as a two-dimensional profiler to cover the measurement ranges of up to 50 {mu}m in depth and up to 15 mm in lateral length. Experimental results were carried out using calibrated specimens for roughness measurement. In this system, the optical lateral resolution is 0.5 {mu}m, and the depth resolution, defined by noise-limited approach, is 15 nm.

  14. Direct contribution of axial impact compressive load to anterior tibial load during simulated ski landing impact.

    Science.gov (United States)

    Yeow, C H; Lee, P V S; Goh, J C H

    2010-01-19

    Anterior tibial loading is a major factor involved in the anterior cruciate ligament (ACL) injury mechanism during ski impact landing. We sought to investigate the direct contribution of axial impact compressive load to anterior tibial load during simulated ski landing impact of intact knee joints without quadriceps activation. Twelve porcine knee specimens were procured. Four specimens were used as non-impact control while the remaining eight were mounted onto a material-testing system at 70 degrees flexion and subjected to simulated landing impact, which was successively repeated with incremental actuator displacement. Four specimens from the impacted group underwent pre-impact MRI for tibial plateau angle measurements while the other four were subjected to histology and microCT for cartilage morphology and volume assessment. The tibial plateau angles ranged from 29.4 to 38.8 degrees . There was a moderate linear relationship (Y=0.16X; R(2)=0.64; p<0.001) between peak axial impact compressive load (Y) and peak anterior tibial load (X). The anterior and posterior regions in the impacted group sustained surface cartilage fraying, superficial clefts and tidemark disruption, compared to the control group. MicroCT scans displayed visible cartilage deformation for both anterior and posterior regions in the impacted group. Due to the tibial plateau angle, increased axial impact compressive load can directly elevate anterior tibial load and hence contribute to ACL failure during simulated landing impact. Axial impact compressive load resulted in shear cartilage damage along anterior-posterior tibial plateau regions, due to its contribution to anterior tibial loading. This mechanism plays an important role in elevating ACL stress and cartilage deformation during impact landing.

  15. Axial vibration analysis of nanocones based on nonlocal elasticity theory

    Institute of Scientific and Technical Information of China (English)

    Shu-Qi Guo; Shao-Pu Yang

    2012-01-01

    Carbon nanocones have quite fascinating electronic and structural properties,whose axial vibration is seldom investigated in previous studies.In this paper,based on a nonlocal elasticity theory,a nonuniform rod model is applied to investigate the small-scale effect and the nonuniform effect on axial vibration of nanocones.Using the modified Wentzel-Brillouin-Kramers (WBK) method,an asymptotic solution is obtained for the axial vibration of general nonuniform nanorods.Then,using similar procedure,the axial vibration of nanocones is analyzed for nonuniform parameters,mode number and nonlocal parameters.Explicit expressions are derived for mode frequencies of clamped-clamped and clamped-free boundary conditions.It is found that axial vibration frequencies are highly overestimated by the classical rod model because of ignorance of the effect of small length scale.

  16. On Stationary Axially Symmetric Solutions in Brans-Dicke Theory

    CERN Document Server

    Kirezli, Pınar

    2015-01-01

    Stationary axially symmetric Brans-Dicke-Maxwell solutions are re-examined in the framework of the Brans-Dicke theory. We see that, employing a particular parametrization of the standard axially symmetric metric simplifies the procedure of obtaining the Ernst equations for axially symmetric electro-vacuum space-times for this theory. This analysis also permit us to construct a two parameter extension in both Jordan and Einstein frames of an old solution generating technique frequently used to construct axially symmetric solutions for Brans-Dicke theory from a seed solution of General Relativity. As applications of this technique, several known and new solutions are constructed including a general axially symmetric BD-Maxwell solution of Plebanski-Demianski with vanishing cosmological constant, i.e. the Kinnersley solution and general magnetized Kerr-Newman type solutions. Some physical properties and circular motion of test particles for a particular subclass of Kinnersley solution, i.e. Kerr-Newman-NUT type ...

  17. Femtosecond scanning tunneling microscope

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, A.J.; Donati, G.P.; Rodriguez, G.; Gosnell, T.R.; Trugman, S.A.; Some, D.I.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). By combining scanning tunneling microscopy with ultrafast optical techniques we have developed a novel tool to probe phenomena on atomic time and length scales. We have built and characterized an ultrafast scanning tunneling microscope in terms of temporal resolution, sensitivity and dynamic range. Using a novel photoconductive low-temperature-grown GaAs tip, we have achieved a temporal resolution of 1.5 picoseconds and a spatial resolution of 10 nanometers. This scanning tunneling microscope has both cryogenic and ultra-high vacuum capabilities, enabling the study of a wide range of important scientific problems.

  18. Scanning the phenomenological MSSM

    CERN Document Server

    Wuerzinger, Jonas

    2017-01-01

    A framework to perform scans in the 19-dimensional phenomenological MSSM is developed and used to re-evaluate the ATLAS experiments' sensitivity to R-parity-conserving supersymmetry with LHC Run 2 data ($\\sqrt{s}=13$ TeV), using results from 14 separate ATLAS searches. We perform a $\\tilde{t}_1$ dedicated scan, only considering models with $m_{\\tilde{t}_1}<1$ TeV, while allowing both a neutralino ($\\tilde{\\chi}_1^0$) and a sneutrino ($\\tilde{\

  19. Adaptive Optical Scanning Holography

    Science.gov (United States)

    Tsang, P. W. M.; Poon, Ting-Chung; Liu, J.-P.

    2016-01-01

    Optical Scanning Holography (OSH) is a powerful technique that employs a single-pixel sensor and a row-by-row scanning mechanism to capture the hologram of a wide-view, three-dimensional object. However, the time required to acquire a hologram with OSH is rather lengthy. In this paper, we propose an enhanced framework, which is referred to as Adaptive OSH (AOSH), to shorten the holographic recording process. We have demonstrated that the AOSH method is capable of decreasing the acquisition time by up to an order of magnitude, while preserving the content of the hologram favorably. PMID:26916866

  20. Multivariate Analysis of Factors Associated With Axial Symptoms in Unilateral Expansive Open-Door Cervical Laminoplasty With Miniplate Fixation.

    Science.gov (United States)

    Chen, Hua; Liu, Hao; Deng, Yuxiao; Gong, Quan; Li, Tao; Song, Yueming

    2016-01-01

    Retrospective case-control study.Unilateral expansive open-door cervical laminoplasty with miniplate fixation is an efficient and increasing popular surgery for multilevel cervical spondylotic myelopathy. Axial symptoms are the most frequent complaints after cervical laminoplasty. But the mechanisms have not been fully clarified yet.The objective of this study is to compare the clinical and radiologic data between patients with or without axial symptoms and to investigate the factors associated with axial symptoms by multivariate analysis in cervical laminoplasty with miniplate fixation.A total of 129 patients who underwent cervical laminoplasty with miniplate fixation were comprised from August 2009 to March 2014. Patients were grouped according to whether they suffered from postoperative axial symptoms (PA) or not (NA). The clinical data including gender, age, duration of symptoms, diagnosis type, medical comorbidity, operative level, blood loss, operative time, pre- and post-Japanese Orthopedic Association (JOA) score, JOA recovery rates, and other complications were recorded. The radiologic data including cervical canal diameter, C2-7 Cobb angle, cervical range of motion (ROM), cross-sectional area, open angle, hinge union, and facet joint destroyed would be measured according to X-ray plain and CT scan images. The univariate analysis and multivariate logistic regression analysis were performed.There were 39 patients in PA group and 90 patients in NA group. Both groups gained significant JOA improvement postoperatively (P  0.05). The multivariate analysis showed that the negative change of cervical ROM (OR = 1.062, P = 0.047) and facet joints destroyed (OR = 0.661, P = 0.024) were related to axial symptoms.The change of cervical ROM and facet joints destroyed by miniscrews might be associated with axial symptoms after cervical laminoplasty with miniplate fixation. Cervical spine surgeons should carefully operate to decrease the injury of

  1. Axial Vibration Confinement in Nonhomogenous Rods

    Directory of Open Access Journals (Sweden)

    S. Choura

    2005-01-01

    Full Text Available A design methodology for the vibration confinement of axial vibrations in nonhomogenous rods is proposed. This is achieved by a proper selection of a set of spatially dependent functions characterizing the rod material and geometric properties. Conditions for selecting such properties are established by constructing positive Lyapunov functions whose derivative with respect to the space variable is negative. It is shown that varying the shape of the rod alone is sufficient to confine the vibratory motion. In such a case, the vibration confinement requires that the eigenfunctions be exponentially decaying functions of space, where the notion of spatial domain stability is introduced as a concept dual to that of the time domain stability. It is also shown that vibration confinement can be produced if the rod density and/or stiffness are varied with respect to the space variable while the cross-section area is kept constant. Several case studies, supporting the developed conditions imposed on the spatially dependent functions for vibration confinement in vibrating rods, are discussed. Because variation in the geometric and material properties might decrease the critical buckling loads, we also discuss the buckling problem.

  2. Multimode interaction in axially excited cylindrical shells

    Directory of Open Access Journals (Sweden)

    Silva F. M. A.

    2014-01-01

    Full Text Available Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural frequencies. The shell is modelled using the Donnell nonlinear shallow shell theory and the discretized equations of motion are obtained by applying the Galerkin method. For this, a modal solution that takes into account the modal interaction among the relevant modes and the influence of their companion modes (modes with rotational symmetry, which satisfies the boundary and continuity conditions of the shell, is derived. Special attention is given to the 1:1:1:1 internal resonance (four interacting modes. Solving numerically the governing equations of motion and using several tools of nonlinear dynamics, a detailed parametric analysis is conducted to clarify the influence of the internal resonances on the bifurcations, stability boundaries, nonlinear vibration modes and basins of attraction of the structure.

  3. Axially Symmetric Post-Newtonian Stellar Systems

    Directory of Open Access Journals (Sweden)

    Camilo Akímushkin

    2010-06-01

    Full Text Available We introduce a method to obtain self-consistent, axially symmetric disklike stellar models in the first post-Newtonian (1PN approximation. By using in the field equations of the 1PN approximation a distribution function (DF corresponding to a Newtonian model, two fundamental equations determining the 1PN corrections are obtained. The rotation curves of the corrected models differs from the classical ones and the corrections are clearly appreciable with values of the mass and radius of a typical galaxy. On the other hand, the relativistic mass correction can be ignored for all models. Resumen. Presentamos un método para obtener modelos estelares discoidales, axialmente simétricos, auto-consistentes en la primera aproximación post-Newtoniana (1PN. Usando en las ecuaciones de campo de la aproximación 1PN una función de distribución conocida (DF que corresponde a un modelo Newtoniano, se obtienen dos ecuaciones fundamentales para determinar las correcciones 1PN. Las curvas de rotación de los modelos corregidos difieren de las clásicas y las correcciones son claramente apreciables con los valores de la masa y el radio de una galaxia típica. Por otro lado, la corrección relativista de la masa se puede ignorar para todos los modelos.

  4. New treatment targets for axial spondyloarthritis.

    Science.gov (United States)

    Sieper, Joachim

    2016-12-01

    Axial spondyloarthritis (axSpA) patients can be divided into those with structural damage in the SI joint visible on X-rays, termed radiographic axSpA or AS, and those in an earlier phase of the disease, without structural damage in the SI joint, termed non-radiographic axSpA. TNF-blockers have been shown to be highly effective in the treatment of active axSpA. Interestingly, conventional DMARDs and also non-TNF-blocker biologics targeting IL-1, IL-6 and T cells (abatacept) are not effective. Recent interest has focused on the cytokines IL-23 and IL-17 as potential treatment targets in axSpA. An open-label trial with ustekinumab showed a good efficacy in AS patients. Two placebo-controlled phase 3 trials with a mAb blocking IL-17, secukinumab, showed a good reduction in disease activity, similar to that shown for TNF blockers. Probably triggered by inflammation, new bone formation is another hallmark in AS and a potentially important treatment target. However, a previously reported inhibitory effect of NSAID treatment could not be confirmed in a recent NSAID trial.

  5. Vertebrate Axial Patterning: From Egg to Asymmetry.

    Science.gov (United States)

    Houston, Douglas W

    2017-01-01

    The emergence of the bilateral embryonic body axis from a symmetrical egg has been a long-standing question in developmental biology. Historical and modern experiments point to an initial symmetry-breaking event leading to localized Wnt and Nodal growth factor signaling and subsequent induction and formation of a self-regulating dorsal "organizer." This organizer forms at the site of notochord cell internalization and expresses primarily Bone Morphogenetic Protein (BMP) growth factor antagonists that establish a spatiotemporal gradient of BMP signaling across the embryo, directing initial cell differentiation and morphogenesis. Although the basics of this model have been known for some time, many of the molecular and cellular details have only recently been elucidated and the extent that these events remain conserved throughout vertebrate evolution remains unclear. This chapter summarizes historical perspectives as well as recent molecular and genetic advances regarding: (1) the mechanisms that regulate symmetry-breaking in the vertebrate egg and early embryo, (2) the pathways that are activated by these events, in particular the Wnt pathway, and the role of these pathways in the formation and function of the organizer, and (3) how these pathways also mediate anteroposterior patterning and axial morphogenesis. Emphasis is placed on comparative aspects of the egg-to-embryo transition across vertebrates and their evolution. The future prospects for work regarding self-organization and gene regulatory networks in the context of early axis formation are also discussed.

  6. Nitinol stent design - understanding axial buckling.

    Science.gov (United States)

    McGrath, D J; O'Brien, B; Bruzzi, M; McHugh, P E

    2014-12-01

    Nitinol׳s superelastic properties permit self-expanding stents to be crimped without plastic deformation, but its nonlinear properties can contribute towards stent buckling. This study investigates the axial buckling of a prototype tracheobronchial nitinol stent design during crimping, with the objective of eliminating buckling from the design. To capture the stent buckling mechanism a computational model of a radial force test is simulated, where small geometric defects are introduced to remove symmetry and allow buckling to occur. With the buckling mechanism ascertained, a sensitivity study is carried out to examine the effect that the transitional plateau region of the nitinol loading curve has on stent stability. Results of this analysis are then used to redesign the stent and remove buckling. It is found that the transitional plateau region can have a significant effect on the stability of a stent during crimping, and by reducing the amount of transitional material within the stent hinges during loading the stability of a nitinol stent can be increased.

  7. Análisis de la fuerza axial en un transportador de sinfín // Analysis of axial force in a screw conveyor.

    Directory of Open Access Journals (Sweden)

    F. Aguilar Parés

    1999-01-01

    Full Text Available Durante el movimiento de un material en un transportador de sinfín surge una fuerza en dirección axial que influye en laselección de uno de los cojinetes de apoyo del equipo. En el artículo aparecen algunas soluciones constructivas que tienen encuentan la fuerza axial. Por otro lado se establece la relación entre la fuerza axial y el empuje axial y se precisa de quiendepende el sentido del empuje axial. Por último se propone un modelo matemático que relaciona la fuerza axial con la potenciarequerida por el equipo.Palabras claves: Transportador de sinf in, fuerza axial , empuje axial ._________________________________________________________________________AbstractDuring the movement of material in a screw conveyor surge a force in axial direction that influence in the selection of one ofthe equipment support bearings. Some constructive solutions appear in the article for considering the axial force. In the otherhand it is established the relation between axial force and axial thurst and it is precised whose direction thurst axial depend of.Finally it is proposed a mathematic model that relates the axial force with the power required by the equipment.Key words: Screw conveyor, axial force, axial thurst .

  8. Applications. SCANS Plans Portfolio.

    Science.gov (United States)

    Sample, Barbara

    This guide assists English-as-a-Second-Language educators in helping students fill out simple application forms. The guide discusses performance outcomes, communications teaching points, SCANS (Secretary's Committee on Achieving Necessary Skills) competencies, classroom configurations, materials, and procedures. Blank forms, suitable for…

  9. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... Español More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Thyroid Scan ... often unattainable using other imaging procedures. Tell your doctor if there’s a possibility you are pregnant or ...

  10. Scanning bubble chamber pictures

    CERN Multimedia

    1974-01-01

    These were taken at the 2 m hydrogen bubble chamber. The photo shows an early Shiva system where the pre-measurements needed to qualify the event were done manually (cf photo 7408136X). The scanning tables were located in bld. 12. Gilberte Saulmier sits on foreground, Inge Arents at centre.

  11. Sinus MRI scan

    Science.gov (United States)

    ... A CT scan may be preferred in emergency cases, since it is faster and often available in the emergency room. Note: MRI is not as effective as CT in defining the anatomy of the sinuses, and therefore is not typically used for suspected acute sinusitis.

  12. SCANNING-DLTS

    OpenAIRE

    Breitenstein, O.

    1989-01-01

    Scanning Deep Level Transient Spectroscopy (SDLTS) is a current SEM technique for the detection of the local distribution of deep level centres in semiconductors. The contribution deals with the physical foundations of the SDLTS technique and it discusses the demands on the instrumentation. The measurement practice is described and illustrated by several experimental examples. Finally, the possibilities and limitations of SDLTS are critically reviewed.

  13. Active axial spondyloarthritis: potential role of certolizumab pegol

    Directory of Open Access Journals (Sweden)

    Ranatunga S

    2014-02-01

    Full Text Available Sriya Ranatunga, Anne V Miller Department of Internal Medicine, Southern Illinois University School of Medicine, Springfield, IL, USA Abstract: The axial spondyloarthropathies are a group of chronic inflammatory diseases that predominantly affect the axial joints. This group includes ankylosing spondylitis and nonradiographic axial spondyloarthropathy. While the pathogenesis of axial spondyloarthropathies is not clear, immunologically active tissues primarily include the entheses, ie, the areas where ligaments, tendons, and joint capsules attach to bone and to the annulus fibrosis at the vertebrae. One of the major mediators of the immune response in this group of diseases is tumor necrosis factor-alpha (TNFα. Blockade of TNFα results in reduced vascularity and inflammatory cell infiltration in the synovial tissues of affected joints. Certolizumab pegol (CZP is an Fc-free, PEGylated anti-TNFα monoclonal antibody. CZP has unique properties that differ from other available TNFα inhibitors by virtue of its lack of an Fc region, which minimizes potential Fc-mediated effects, and its PEGylation, which improves drug pharmacokinetics and bioavailability. It has been shown in clinical trials that CZP improves patient outcomes and reduces inflammation in the sacroiliac joints and spine in both ankylosing spondylitis and nonradiographic axial spondyloarthropathies. These data support CZP as a treatment option for axial spondyloarthropathies. Keywords: axial spondyloarthropathy, certolizumab pegol, anti-tumor necrosis factor-alpha, therapy

  14. Axial elongation following prolonged near work in myopes and emmetropes.

    Science.gov (United States)

    Woodman, Emily C; Read, Scott A; Collins, Michael J; Hegarty, Katherine J; Priddle, Scott B; Smith, Josephine M; Perro, Judd V

    2011-05-01

    To investigate the influence of a period of sustained near work upon axial length in groups of emmetropes (EMM) and myopes. Forty young adult subjects (20 myopes and 20 emmetropes) were recruited for the study. Myopes were further classified as early onset (EOM), late onset (LOM), stable (SM) or progressing (PM) subgroups. Axial length was measured with the IOLMaster instrument before, immediately after and then again 10 min after a continuous 30 min near task of 5 D accommodation demand. Measures of distance objective refraction were also collected. Significant changes in axial length were observed immediately following the near task. EOM axial length elongated on average by 0.027±0.021 mm, LOM by 0.014±0.020 mm, EMM by 0.010±0.015 mm, PM by 0.031±0.022 mm and SM by 0.014±0.018 mm. At the conclusion of the 10 min regression period, axial length measures were not significantly different from baseline values. Axial elongation was observed following a prolonged near task. Both EOM and PM groups showed increases in axial length that were significantly greater than emmetropes.

  15. Comparison of 2 A-scans.

    Science.gov (United States)

    Norrby, Sverker; Lydahl, Eva; Koranyi, Gabor; Taube, Mikaela

    2003-01-01

    To compare 2 A-scan instruments with regard to differences in measured results for the same patient sample. St. Erik's Eye Hospital, Stockholm, Sweden. In a study to evaluate the lens-haptic plane concept of intraocular lens (IOL) power calculation, 148 patients eligible for cataract surgery were measured with 2 different A-scan instruments (BVI Axis and Sonomed 1500). The axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) results were analyzed for systematic differences and random errors. The Sonomed 1500 measured systematically longer than the BVI Axis for AL (0.41 mm) and ACD (0.28 mm), although the correlation was good (r = 0.99 and r = 0.87, respectively). The LT correlated poorly (r = 0.18) and showed no systematic trend. The relative random errors (standard deviations) in ACD (7.2%) and LT (18.6%) were larger than that of the AL (0.8%). The systematic difference in the AL corresponds to a 1.0 diopter difference in the A-constant. The large random errors in the ACD and LT reduce their value as predictors of postoperative IOL position in formulas that use them. Systematic differences in AL can be large enough to require separate formula constants for different pieces of equipment. If this is the situation in 1 setting, there is a risk of mistakes. This confusion could be avoided if there were an agreed standard and a universal calibration procedure for instruments intended for AL measurement.

  16. Tensile Property of Bi-axial Warp Knitted Structure

    Institute of Scientific and Technical Information of China (English)

    沈为

    2003-01-01

    The tensile property of bi-axial warp knitted fabrics is tested and compared with that of the plain weave fabric. The results show that there are obvious differences between the tensile property of a bi-axial warp knitted fabric and that of a plain weave fabric.The former can give fuller play to the property of a high modulus yarn than the latter. The tensile strength of a bi-axial warp knitted fabric is linear with the number of yarns in the direction of force.

  17. The axial charges of the hidden-charm pentaquark states

    CERN Document Server

    Wang, Guang-Juan; Zhu, Shi-Lin

    2016-01-01

    With the chiral quark model, we have calculated the axial charges of the pentaquark states with $(I,I_3)=(\\frac{1}{2},\\frac{1}{2})$ and $J^{P}=\\frac{1}{2}^{\\pm},\\frac{3}{2}^{\\pm},\\frac{5}{2}^{\\pm}$. The $P_c$ states with the same $J^P$ quantum numbers but different color-spin-flavor configurations have very different axial charges, which encode important information on their underlying structures. For some of the $J^{P}=\\frac{3}{2}^{\\pm}$ or $\\frac{5}{2}^{\\pm}$ pentaquark states, their axial charges are much smaller than that of the proton.

  18. Dynamic Analysis of Axial Magnetic Forces for DVD Spindle Motors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The axial magnetic force, induced by the complicated flux linkage distribution from rotor magnet and stator slotted, is constructed by different relative heights and calculated by 3D finite element method (FEM) to analyze the dynamic characteristics for a DVD spindle motor. The axial magnetic force is designed to provide an axial stiffness and govern the natural frequency of the dynamic performance. According to the simulation results and experimental measurements, the dynamic behaviors are significantly improved with a variation of relative height of rotor magnet and stator slotted on a DVD spindle motor.

  19. Gravitational waves from the axial perturbations of hyperon stars

    Institute of Scientific and Technical Information of China (English)

    Wen De-Hua; Yan Jing; Liu Xue-Mei

    2012-01-01

    The eigen-frequencies of the axial w-mode oscillations of hyperon stars are examined.It is shown that as the appearance of hyperons softens the equation of state of the super-density matter,the frequency of gravitational waves from the axial w-mode of hyperon star becomes smaller than that of a traditional neutron star at the same stellar mass.Moreover,the eigenfrequencies of hyperon stars also have scaling universality.It is shown that the EURO thirdgeneration gravitational-wave detector has the potential to detect the gravitational-wave signal emitted from the axial w-mode oscillations of a hyperon star.

  20. Dispositivos de asistencia ventricular de tipo axial

    Directory of Open Access Journals (Sweden)

    Albert Miralles Cassina

    2009-04-01

    Full Text Available El uso de dispositivos de asistencia ventricular se ha ido extendiendo en las últimas décadas. La mejora de los resultados ha ido acompañada del diseño de nuevos aparatos más pequeños y eficientes como son las bombas de flujo axial. las características técnicas básicas de estos dispositivos se hallan en la generación de un flujo continuo unidireccional conseguido mediante sistemas de turbina que obtienen su alimentación de una fuente eléctrica. Las ventajas principales de estos dispositivos son: su facilidad de implantación por su tamaño reducido, su prolongada durabilidad gracias a su sencillo diseño y su eficiencia energética al utilizar energía eléctrica. Su utilidad se ha podido demostrar en diferentes indicaciones de asistencia circulatoria mecánica, como en el caso de puente al trasplante o dispositivo de recuperación miocárdica, si bien donde radica más interés es en su uso como sistemas de asistencia circulatoria mecánica definitiva. Existe una variedad de modelos de diversos diseños. Son dispositivos que permiten soporte normalmente univentricular izquierdo, que se implantan en el tórax con cánula de entrada a nivel ventricular y cánula de salida a nivel aórtico. En este artículo se efectúa una descripción de los principales sistemas disponibles en la actualidad, comentando las características técnicas, ventajas e inconvenientes y un resumen de la experiencia existente.

  1. Revealing atropisomer axial chirality in drug discovery.

    Science.gov (United States)

    LaPlante, Steven R; Edwards, Paul J; Fader, Lee D; Jakalian, Araz; Hucke, Oliver

    2011-03-07

    An often overlooked source of chirality is atropisomerism, which results from slow rotation along a bond axis due to steric hindrance and/or electronic factors. If undetected or not managed properly, this time-dependent chirality has the potential to lead to serious consequences, because atropisomers can be present as distinct enantiomers or diastereoisomers with their attendant different properties. Herein we introduce a strategy to reveal and classify compounds that have atropisomeric chirality. Energy barriers to axial rotation were calculated using quantum mechanics, from which predicted high barriers could be experimentally validated. A calculated rotational energy barrier of 20 kcal mol(-1) was established as a suitable threshold to distinguish between atropisomers and non-atropisomers with a prediction accuracy of 86%. This methodology was applied to subsets of drug databases in the course of which atropisomeric drugs were identified. In addition, some drugs were exposed that were not yet known to have this chiral attribute. The most valuable utility of this tool will be to predict atropisomerism along the drug discovery pathway. When used in concert with our compound classification scheme, decisions can be made during early discovery stages such as "hit-to-lead" and "lead optimization," to foresee and validate the presence of atropisomers and to exercise options of removing, further stabilizing, or rendering the chiral axis of interest more freely rotatable via SAR design, thereby decreasing this potential liability within a compound series. The strategy can also improve drug development plans, such as determining whether a drug or series should be developed as a racemic mixture or as an isolated single compound. Moreover, the work described herein can be extended to other chemical fields that require the assessment of potential chiral axes.

  2. The Design Method of Axial Flow Runners Focusing on Axial Flow Velocity Uniformization and Its Application to an Ultra-Small Axial Flow Hydraulic Turbine

    Directory of Open Access Journals (Sweden)

    Yasuyuki Nishi

    2016-01-01

    Full Text Available We proposed a portable and ultra-small axial flow hydraulic turbine that can generate electric power comparatively easily using the low head of open channels such as existing pipe conduits or small rivers. In addition, we proposed a simple design method for axial flow runners in combination with the conventional one-dimensional design method and the design method of axial flow velocity uniformization, with the support of three-dimensional flow analysis. Applying our design method to the runner of an ultra-small axial flow hydraulic turbine, the performance and internal flow of the designed runner were investigated using CFD analysis and experiment (performance test and PIV measurement. As a result, the runners designed with our design method were significantly improved in turbine efficiency compared to the original runner. Specifically, in the experiment, a new design of the runner achieved a turbine efficiency of 0.768. This reason was that the axial component of absolute velocity of the new design of the runner was relatively uniform at the runner outlet in comparison with that of the original runner, and as a result, the negative rotational flow was improved. Thus, the validity of our design method has been verified.

  3. Self-gated fat-suppressed cardiac cine MRI.

    Science.gov (United States)

    Ingle, R Reeve; Santos, Juan M; Overall, William R; McConnell, Michael V; Hu, Bob S; Nishimura, Dwight G

    2015-05-01

    To develop a self-gated alternating repetition time balanced steady-state free precession (ATR-SSFP) pulse sequence for fat-suppressed cardiac cine imaging. Cardiac gating is computed retrospectively using acquired magnetic resonance self-gating data, enabling cine imaging without the need for electrocardiogram (ECG) gating. Modification of the slice-select rephasing gradients of an ATR-SSFP sequence enables the acquisition of a one-dimensional self-gating readout during the unused short repetition time (TR). Self-gating readouts are acquired during every TR of segmented, breath-held cardiac scans. A template-matching algorithm is designed to compute cardiac trigger points from the self-gating signals, and these trigger points are used for retrospective cine reconstruction. The proposed approach is compared with ECG-gated ATR-SSFP and balanced steady-state free precession in 10 volunteers and five patients. The difference of ECG and self-gating trigger times has a variability of 13 ± 11 ms (mean ± SD). Qualitative reviewer scoring and ranking indicate no statistically significant differences (P > 0.05) between self-gated and ECG-gated ATR-SSFP images. Quantitative blood-myocardial border sharpness is not significantly different among self-gated ATR-SSFP ( 0.61±0.15 mm -1), ECG-gated ATR-SSFP ( 0.61±0.15 mm -1), or conventional ECG-gated balanced steady-state free precession cine MRI ( 0.59±0.15 mm -1). The proposed self-gated ATR-SSFP sequence enables fat-suppressed cardiac cine imaging at 1.5 T without the need for ECG gating and without decreasing the imaging efficiency of ATR-SSFP. © 2014 Wiley Periodicals, Inc.

  4. Horizon Scanning for Pharmaceuticals

    DEFF Research Database (Denmark)

    Lepage-Nefkens, Isabelle; Douw, Karla; Mantjes, GertJan

    will collect country-specific information, liaise between the central HS unit and country-specific clinical and other experts, coordinate the national prioritization process (to select products for early assessment), and communicate the output of the HSS to national decision makers.  The outputs of the joint...... for a joint horizon scanning system (HSS).  We propose to create a central “horizon scanning unit” to perform the joint HS activities (a newly established unit, an existing HS unit, or a third party commissioned and financed by the collaborating countries). The unit will be responsible for the identification...... and filtration of new and emerging pharmaceutical products. It will maintain and update the HS database, organise company pipeline meetings, and disseminate the HSS’s outputs.  The HS unit works closely together with the designated national HS experts in each collaborating country. The national HS experts...

  5. The Nonradiographic Axial Spondyloarthritis, the Radiographic Axial Spondyloarthritis, and Ankylosing Spondylitis: The Tangled Skein of Rheumatology

    Science.gov (United States)

    Rawat, Roopa; Agrawal, Neha; Patil, Nilesh S.

    2017-01-01

    Since 1984 the diagnosis of ankylosing spondylitis (AS) has been based upon the modified New York (mNY) criteria with mandatory presence of radiographic sacroiliitis, without which the diagnosis is not tenable. However, it may take years or decades for radiographic sacroiliitis to develop delaying the diagnosis for long periods. It did not matter in the past because no effective treatment was available. However, with the availability of a highly effective treatment, namely, tumour necrosis factor-α inhibitors (TNFi), the issue of early diagnosis of AS acquired an urgency. The Assessment of SpondyloArthritis International Society (ASAS) classification criteria published in 2009 was a significant step towards this goal. These criteria described an early stage of the disease where sacroiliitis was demonstrable only on MRI but not on standard radiograph. Therefore, this stage of the disease was labelled “nonradiographic axial SpA” (nr-axSpA). But questions have been raised if, in search of early diagnosis, specificity was compromised. The Federal Drug Administration (FDA, USA) withheld approval for the use of TNFi in patients with nr-axSpA because of issues related to the specificity of these criteria. This review attempts to clarify some of these aspects of the nr-axSpA-AS relationship and also tries to answer the question whether ASAS classifiable radiographic axial spondyloarthritis (r-axSpA) term can be interchangeably used with the term AS. PMID:28555158

  6. Scanning Quantum Decoherence Microscopy

    OpenAIRE

    2008-01-01

    The use of qubits as sensitive magnetometers has been studied theoretically and recent demonstrated experimentally. In this paper we propose a generalisation of this concept, where a scanning two-state quantum system is used to probe the subtle effects of decoherence (as well as its surrounding electromagnetic environment). Mapping both the Hamiltonian and decoherence properties of a qubit simultaneously, provides a unique image of the magnetic (or electric) field properties at the nanoscale....

  7. Scanning micro-sclerometer

    Science.gov (United States)

    Oliver, Warren C.; Blau, Peter J.

    1994-01-01

    A scanning micro-sclerometer measures changes in contact stiffness and correlates these changes to characteristics of a scratch. A known force is applied to a contact junction between two bodies and a technique employing an oscillating force is used to generate the contact stiffness between the two bodies. As the two bodies slide relative to each other, the contact stiffness changes. The change is measured to characterize the scratch.

  8. Scanning ultrafast electron microscopy.

    Science.gov (United States)

    Yang, Ding-Shyue; Mohammed, Omar F; Zewail, Ahmed H

    2010-08-24

    Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability.

  9. Scanning ultrafast electron microscopy

    Science.gov (United States)

    Yang, Ding-Shyue; Mohammed, Omar F.; Zewail, Ahmed H.

    2010-01-01

    Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability. PMID:20696933

  10. Forensic Scanning Electron Microscope

    Science.gov (United States)

    Keeley, R. H.

    1983-03-01

    The scanning electron microscope equipped with an x-ray spectrometer is a versatile instrument which has many uses in the investigation of crime and preparation of scientific evidence for the courts. Major applications include microscopy and analysis of very small fragments of paint, glass and other materials which may link an individual with a scene of crime, identification of firearms residues and examination of questioned documents. Although simultaneous observation and chemical analysis of the sample is the most important feature of the instrument, other modes of operation such as cathodoluminescence spectrometry, backscattered electron imaging and direct x-ray excitation are also exploited. Marks on two bullets or cartridge cases can be compared directly by sequential scanning with a single beam or electronic linkage of two instruments. Particles of primer residue deposited on the skin and clothing when a gun is fired can be collected on adhesive tape and identified by their morphology and elemental composition. It is also possible to differentiate between the primer residues of different types of ammunition. Bullets may be identified from the small fragments left behind as they pass through the body tissues. In the examination of questioned documents the scanning electron microscope is used to establish the order in which two intersecting ink lines were written and to detect traces of chemical markers added to the security inks on official documents.

  11. Emulation and design of terahertz reflection-mode confocal scanning microscopy based on virtual pinhole

    Science.gov (United States)

    Yang, Yong-fa; Li, Qi

    2014-12-01

    In the practical application of terahertz reflection-mode confocal scanning microscopy, the size of detector pinhole is an important factor that determines the performance of spatial resolution characteristic of the microscopic system. However, the use of physical pinhole brings some inconvenience to the experiment and the adjustment error has a great influence on the experiment result. Through reasonably selecting the parameter of matrix detector virtual pinhole (VPH), it can efficiently approximate the physical pinhole. By using this approach, the difficulty of experimental calibration is reduced significantly. In this article, an imaging scheme of terahertz reflection-mode confocal scanning microscopy that is based on the matrix detector VPH is put forward. The influence of detector pinhole size on the axial resolution of confocal scanning microscopy is emulated and analyzed. Then, the parameter of VPH is emulated when the best axial imaging performance is reached.

  12. Radial breathing mode of carbon nanotubes subjected to axial pressure.

    Science.gov (United States)

    Lei, Xiao-Wen; Ni, Qing-Qing; Shi, Jin-Xing; Natsuki, Toshiaki

    2011-08-11

    In this paper, a theoretical analysis of the radial breathing mode (RBM) of carbon nanotubes (CNTs) subjected to axial pressure is presented based on an elastic continuum model. Single-walled carbon nanotubes (SWCNTs) are described as an individual elastic shell and double-walled carbon nanotubes (DWCNTs) are considered to be two shells coupled through the van der Waals force. The effects of axial pressure, wave numbers and nanotube diameter on the RBM frequency are investigated in detail. The validity of these theoretical results is confirmed through the comparison of the experiment, calculation and simulation. Our results show that the RBM frequency is linearly dependent on the axial pressure and is affected by the wave numbers. We concluded that RBM frequency can be used to characterize the axial pressure acting on both ends of a CNT.

  13. The geometrical theory of diffraction for axially symmetric reflectors

    DEFF Research Database (Denmark)

    Rusch, W.; Sørensen, O.

    1975-01-01

    The geometrical theory of diffraction (GTD) (cf. [1], for example) may be applied advantageously to many axially symmetric reflector antenna geometries. The material in this communication presents analytical, computational, and experimental results for commonly encountered reflector geometries...

  14. Time Domain Terahertz Axial Computed Tomography Non Destructive Evaluation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to demonstrate key elements of feasibility for a high speed automated time domain terahertz computed axial tomography (TD-THz CT) non destructive...

  15. ANALYSIS OF PULSATILE BLOOD FLOW IN AXIALLY MOVING ARTERIES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to study motional properties of pulsatile blood flow in axially moving arteries, the authors derived some expressions of the pulsatile blood flow from the basic equations of motion for blood and vascular walls, including an axial blood velocity equation, a flow rate equation and a wall shear stress equation, which described not only the overall axial movement of the arteries but also the elastic properties of the vascular walls, discussed the effects of the arterial wall elasticity on the wall shear stress in coronary arteries in terms of these expressions, and analyzed changes of motional properties of pulsatile blood flow between an elastic arterial tube model and a rigid tube model. The results proved the inference by J.E. Moore Jr. et al. (1994) that the axial movement of arteries be as important in determining coronary artery hemodynamics as the elastic property of the vascular wall.

  16. Open-Axial-Field Magnet at ISR intersection I8

    CERN Multimedia

    1979-01-01

    This axial field spectrometer left the central collision region unobstructed in order to ease analysis of secondary particles emitted at large angle. The ISR circulating beams were passing through a hole in the magnet poles.

  17. Axial mesodermal dysplasia complex: a new case with parental consanguinity.

    Science.gov (United States)

    Mota, C R; Azevedo, M; Rocha, G; Manuela, F; Coelho, R; Lima, M R

    2000-01-01

    A female is described with axial mesodermal dysplasia complex (AMDC) born to a consanguineous couple. This is thought to be the first description of a patient with AMDC born to consanguineous parents.

  18. Axial Stringy System of the Kerr Spinning Particle

    CERN Document Server

    Burinskii, A

    2004-01-01

    The structure of classical spinning particle based on the Kerr-Newman black hole (BH) solution is investigated. For large angular momentum, $|a|>>m$, the BH horizons disappear exposing a naked ringlike source which is a circular relativistic string. It was shown recently that electromagnetic excitations of this string lead to the appearance of an extra axial stringy system which consists of two half-infinite strings of opposite chirality. In this paper we consider the relation of this stringy system to the Dirac equation. We also show that the axial strings are the Witten superconducting strings and describe their structure by the Higgs field model where the Higgs condensate is used to regularize axial singularity. We argue that this axial stringy system may play the role of a classical carrier of the wave function.

  19. Time Domain Terahertz Axial Computed Tomography Non Destructive Evaluation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Phase 2 project, we propose to develop, construct, and deliver to NASA a computed axial tomography time-domain terahertz (CT TD-THz) non destructive...

  20. Uniform Decay for Solutions of an Axially Moving Viscoelastic Beam

    Energy Technology Data Exchange (ETDEWEB)

    Kelleche, Abdelkarim, E-mail: kellecheabdelkarim@gmail.com [Université des Sciences et de la Technologie Houari Boumediene, Faculté des Mathématiques (Algeria); Tatar, Nasser-eddine, E-mail: tatarn@Kfupm.edu.sa [King Fahd University of Petroleum and Minerals, Department of Mathematics and Statistics (Saudi Arabia)

    2017-06-15

    The paper deals with an axially moving viscoelastic structure modeled as an Euler–Bernoulli beam. The aim is to suppress the transversal displacement (transversal vibrations) that occur during the axial motion of the beam. It is assumed that the beam is moving with a constant axial speed and it is subject to a nonlinear force at the right boundary. We prove that when the axial speed of the beam is smaller than a critical value, the dissipation produced by the viscoelastic material is sufficient to suppress the transversal vibrations. It is shown that the rate of decay of the energy depends on the kernel which arise in the viscoelastic term. We consider a general kernel and notice that solutions cannot decay faster than the kernel.

  1. Dual-detection confocal microscopy: high-speed surface profiling without depth scanning

    Science.gov (United States)

    Lee, Dong-Ryoung; Gweon, Dae-Gab; Yoo, Hongki

    2016-03-01

    We propose a new method for three-dimensional (3-D) imaging without depth scanning that we refer to as the dual-detection confocal microscopy (DDCM). Compared to conventional confocal microscopy, DDCM utilizes two pinholes of different sizes. DDCM generates two axial response curves which have different stiffness according to the pinhole diameters. The two axial response curves can draw the characteristics curve of the system which shows the relationship between the axial position of the sample and the intensity ratio. Utilizing the characteristic curve, the DDCM reconstructs a 3-D surface profile with a single 2-D scanning. The height of each pixel is calculated by the intensity ratio of the pixel and the intensity ratio curve. Since the height information can be obtained directly from the characteristic curve without depth scanning, a major advantage of DDCM over the conventional confocal microscopy is a speed. The 3-D surface profiling time is dramatically reduced. Furthermore, DDCM can measure 3-D images without the influence of the sample condition since the intensity ratio is independent of the quantum yield and reflectance. We present two types of DDCM, such as a fluorescence microscopy and a reflectance microscopy. In addition, we extend the measurement range axially by varying the pupil function. Here, we demonstrate the working principle of DDCM and the feasibility of the proposed methods.

  2. Axial Anomaly in Lattice Abelian Gauge Theory in Arbitrary Dimensions

    CERN Document Server

    Fujiwara, T; Wu, K; Fujiwara, Takanori; Suzuki, Hiroshi; Wu, Ke

    1999-01-01

    Axial anomaly of lattice abelian gauge theory in hyper-cubic regular lattice in arbitrary even dimensions is investigated by applying the method of exterior differential calculus. The topological invariance, gauge invariance and locality of the axial anomaly determine the explicit form of the topological part. The anomaly is obtained up to a multiplicative constant for finite lattice spacing and can be interpreted as the Chern character of the abelian lattice gauge theory.

  3. Axially symmetric volume constrained anisotropic mean curvature flow

    CERN Document Server

    Palmer, Bennett

    2011-01-01

    We study the long time existence theory for a non local flow associated to a free boundary problem for a trapped non liquid drop. The drop has free boundary components on two horizontal plates and its free energy is anisotropic and axially symmetric. For axially symmetric initial surfaces with sufficiently large volume, we show that the flow exists for all time. Numerical simulations of the curvature flow are presented.

  4. Watson's theorem and the $N\\Delta(1232)$ axial transition

    CERN Document Server

    Alvarez-Ruso, L; Nieves, J; Vacas, M J Vicente

    2016-01-01

    We present a new determination of the $N\\Delta$ axial form factors from neutrino induced pion production data. For this purpose, the model of Hernandez et al., Phys. Rev. D76, 033005 (2007) is improved by partially restoring unitarity. This is accomplished by imposing Watson's theorem on the dominant vector and axial multipoles. As a consequence, a larger $C_5^A(0)$, in good agreement with the prediction from the off-diagonal Goldberger-Treiman relation, is now obtained.

  5. Method to Measure Tone of Axial and Proximal Muscle

    OpenAIRE

    2011-01-01

    The control of tonic muscular activity remains poorly understood. While abnormal tone is commonly assessed clinically by measuring the passive resistance of relaxed limbs1, no systems are available to study tonic muscle control in a natural, active state of antigravity support. We have developed a device (Twister) to study tonic regulation of axial and proximal muscles during active postural maintenance (i.e. postural tone). Twister rotates axial body regions relative to each other about the ...

  6. Axially astigmatic surfaces: different types and their properties

    Science.gov (United States)

    Malacara-Doblado, Daniel; Malacara-Hernandez, Daniel; Garcia-Marquez, Jorge L.

    1996-12-01

    Axially astigmatic surfaces have different curvatures in orthogonal diameters. Toroidal and spherocylindrical optical surfaces are two mathematically different special cases of axially astigmatic surfaces as noted by Menchaca and Malacara (1986), but they are almost identical in the vicinity of the optical axis. The different between these two surfaces increases when the distance to the optical axis increases. We study the general properties of astigmatic surfaces and some special interesting cases.

  7. Aerodynamics and combustion of axial swirlers

    Science.gov (United States)

    Fu, Yongqiang

    A multipoint lean direct injection (LDI) concept was introduced recently in non-premixed combustion to obtain both low NOx emissions and good combustion stability. In this concept, a key feature is the injection of finely atomized fuel into the high-swirling airflow at the combustor dome that provides a homogenous, lean fuel-air mixture. In order to achieve the fine atomization and mixing of the fuel and air quickly and uniformly, a good swirler design should be studied. The focus of this dissertation is to investigate the aerodynamics and combustion of the swirling flow field in a multipoint Lean Direct Injector combustor. A helical axial-vaned swirler with a short internal convergent-divergent venturi was used. Swirlers with various vane angles and fuel nozzle insertion lengths have been designed. Three non-dimensional parameter effects on non-reacting, swirling flow field were studied: swirler number, confinement ratio and Reynolds number. Spray and combustion characteristics on the single swirler were studied to understand the mechanism of fuel-air mixing in this special configuration. Multi-swirler interactions were studied by measuring the confined flow field of a multipoint swirler array with different configurations. Two different swirler arrangements were investigated experimentally, which include a co-swirling array and a counter-swirling array. In order to increase the range of stability of multipoint LDI combustors, an improved design were also conducted. The results show that the degree of swirl and the level of confinement have a clear impact on the mean and turbulent flow fields. The swirling flow fields may also change significantly with the addition of a variety of simulated fuel nozzle insertion lengths. The swirler with short insertion has the stronger swirling flow as compared with the long insertion swirler. Reynolds numbers, with range of current study, will not alter mean and turbulent properties of generated flows. The reaction of the spray

  8. Comparison of MRI fast SPGR single slice scan and continuous dynamic scan in patients with obstructive sleep apnea-hypopnea syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xinyu [Department of Radiology, Medical School Hospital of Qingdao University, 16 Jiangsu Road, Qingdao 266003 (China)], E-mail: myginny2@sina.com; Yang Xue [Department of Radiology, Medical School Hospital of Qingdao University, 16 Jiangsu Road, Qingdao 266003 (China)], E-mail: yangxueqyfy@126.com; Hua Hui [Department of Otorhinolaryngology-Head and Neck Surgery, Medical School Hospital of Qingdao University, Qingdao (China)], E-mail: huahuisky@163.com; Chen Jingjing [Department of Radiology, Medical School Hospital of Qingdao University, 16 Jiangsu Road, Qingdao 266003 (China)], E-mail: chenjingjingsky@126.com

    2009-07-15

    Objective: To evaluate the application value of MRI fast SPGR single slice scan in patients with obstructive sleep apnea-hypopnea syndrome when comparing the images between fast SPGR single slice scan and continuous dynamic scan. Methods: Eighteen patients with obstructive sleep apnea-hypopnea syndrome were examined by fast SPGR single slice scan and continuous dynamic scan in turn. Fast SPGR single slice scans were conducted when the phases of apnea, inspiration and expiration appeared on the respiratory wave of the subjects. Fast SPGR continuous dynamic scans were conducted when the patients were awake and apneic. The scan planes were median sagittal plane and axial planes (the slice of middle part of palate, the slice of inferior part of palate, the slice of middle part of lingual root and the slice of 0.5 cm beneath the free margin of epiglottis). The obstructed sites and the cross-sectional areas of upper airway were compared between the two scan methods. Results: Seven cases showed complete obstruction at the narrowest sites of upper airway when apnea appeared; eleven cases showed marked decrease in cross-sectional areas at the narrowest sites compared with the areas when the patients were awake; two cases manifested multiple narrowness. The obstructed sites showed by the two scan methods were same. The difference of the cross-sectional areas of upper airway between the two scan methods was insignificant (P > 0.05). Conclusion: Fast SPGR single slice scan can accurately reflect the obstructed sites of upper airway when the breath breaks off and is the complementary method of continuous dynamic scan. Sometimes, single slice scan can replace continuous dynamic scan.

  9. High-resolution adaptive optics scanning laser ophthalmoscope with multiple deformable mirrors

    Science.gov (United States)

    Chen, Diana C.; Olivier, Scot S.; Jones; Steven M.

    2010-02-23

    An adaptive optics scanning laser ophthalmoscopes is introduced to produce non-invasive views of the human retina. The use of dual deformable mirrors improved the dynamic range for correction of the wavefront aberrations compared with the use of the MEMS mirror alone, and improved the quality of the wavefront correction compared with the use of the bimorph mirror alone. The large-stroke bimorph deformable mirror improved the capability for axial sectioning with the confocal imaging system by providing an easier way to move the focus axially through different layers of the retina.

  10. Axial blanket for 16NGF Angra 1 fuel type

    Energy Technology Data Exchange (ETDEWEB)

    Sadde, Luciano Martins; Faria, Eduardo Fernandes [Industrias Nucleares do Brasil (INB), Resende, RJ (Brazil)]. E-mails: sadde@inb.gov.br; faria@inb.gov.br; Sang-Keun You [Korea Nuclear Fuel Co. Ltd. (KNFC), Taejon (Korea, Republic of)]. E-mail: skyou@knfc.co.kr

    2007-07-01

    Angra-1, Kori-2 and Krsko are nuclear power plants with the same design. However, the fuel assemblies have some differences in design due to the countries strategies and the differences in the fabrication process. The 16NGF (16x16 Next Generation Fuel) was developed by INB, KNFC and Westinghouse in order to be used in these three nuclear power plants and the 'Axial Blanket' is one of the new features for the 16NGF design. The main purpose of the Axial Blanket Optimization study is to determine which axial blanket enrichment and length would provide the better fuel cycle cost benefit. All of the calculations were performed using Gadolinium as Burnable Absorber and solid pellets type for Axial Blanket. The results indicate 1.8 w/o U235 enrichment and 8 inches length as the best option of Axial Blanket from the fuel cycle cost benefit standpoint. The economy is about 1.8%. The difference in the reload cost in the range between 1.5 and 2.6 w/o U235 enrichment and for the 6 and 8 inches length is not so significant. Due that, from the Fq limit standpoint and also for longer cycle length requirements, a higher axial blanket enrichment (2.6 w/o) and shorter length (6 inches) is recommended. (author)

  11. Reactive control of subsonic axial fan noise in a duct.

    Science.gov (United States)

    Liu, Y; Choy, Y S; Huang, L; Cheng, L

    2014-10-01

    Suppressing the ducted fan noise at low frequencies without varying the flow capacity is still a technical challenge. This study examines a conceived device consisting of two tensioned membranes backed with cavities housing the axial fan for suppression of the sound radiation from the axial fan directly. The noise suppression is achieved by destructive interference between the sound fields from the axial fan of a dipole nature and sound radiation from the membrane via vibroacoustics coupling. A two-dimensional model with the flow effect is presented which allows the performance of the device to be explored analytically. The air flow influences the symmetrical behavior and excites the odd in vacuo mode response of the membrane due to kinematic coupling. Such an asymmetrical effect can be compromised with off-center alignment of the axial fan. Tension plays an important role to sustain the performance to revoke the deformation of the membrane during the axial fan operation. With the design of four appropriately tensioned membranes covered by a cylindrical cavity, the first and second blade passage frequencies of the axial fan can be reduced by at least 20 dB. The satisfactory agreement between experiment and theory demonstrates that its feasibility is practical.

  12. Slow axial drift in three-dimensional granular tumbler flow

    Science.gov (United States)

    Zaman, Zafir; D'Ortona, Umberto; Umbanhowar, Paul B.; Ottino, Julio M.; Lueptow, Richard M.

    2013-07-01

    Models of monodisperse particle flow in partially filled three-dimensional tumblers often assume that flow along the axis of rotation is negligible. We test this assumption, for spherical and double cone tumblers, using experiments and discrete element method simulations. Cross sections through the particle bed of a spherical tumbler show that, after a few rotations, a colored band of particles initially perpendicular to the axis of rotation deforms: particles near the surface drift toward the pole, while particles deeper in the flowing layer drift toward the equator. Tracking of mm-sized surface particles in tumblers with diameters of 8-14 cm shows particle axial displacements of one to two particle diameters, corresponding to axial drift that is 1-3% of the tumbler diameter, per pass through the flowing layer. The surface axial drift in both double cone and spherical tumblers is zero at the equator, increases moving away from the equator, and then decreases near the poles. Comparing results for the two tumbler geometries shows that wall slope causes axial drift, while drift speed increases with equatorial diameter. The dependence of axial drift on axial position for each tumbler geometry is similar when both are normalized by their respective maximum values.

  13. Axial design of nuclear fuel using path relinking; Diseno axial de combustible nuclear utilizando path relinking

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, A.; Torres, M.; Ortiz, J. J.; Perusquia, R.; Hernandez, J. L.; Montes, J. L. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: jacm@nuclear.inin.mx

    2008-07-01

    In the present work the preliminary results were obtained with the zoctli system whose purpose is the axial design of assembly of nuclear fuel under certain considerations. For the mentioned design well-know cells were already used and that they have been proven in diverse cycles of operation in the nuclear power plant of Laguna Verde. The design contemplates fuels assemblies of 10x10 and with 2 water channels. The assembly was distributed in 6 axial zones according to its structure. In order to take to end the optimization is was used the well-known technique like Path relinking and to find the group of previous solutions required by this technique uses the technical Taboo search. In order to work with Path relinking, 5 trajectories was taken in to account from a set of 5 previous solutions generated with theTaboo search, the update of the group of solutions is carried out in dynamic form. In the case of the Taboo search it was used a list of variable size, it was implement an aspiration approach, it was used the vector of frequencies and due to the cost of the evaluation of the objective function, only it was review 5% of the vicinity. For the objective function was considered the limit thermal, the axial profile of power, the effective multiplication factor and the margin of having turned off in cold. In order to prove the design system, it was used a balance cycle with a value of reference of 0.9928 for the effective multiplication factor that is equivalent to a produced energy of 10896 MWd/TU at the end of operation to full power. The designed assemblies were placed both in one of lots different from fresh assemblies on which it counts the referred cycle. At the end one a comparison with the results obtained with other techniques and under similar conditions is made. The results obtained until the moment show an appropriate performance of the system. It is possible to indicate that a small inconvenient is the amount of consumed resources of calculation during

  14. Alternative oblique head CT scanning technique reduces bone artifact and improves interpretability of brainstem anatomy

    Directory of Open Access Journals (Sweden)

    Sam Douglas Kampondeni

    2010-06-01

    Full Text Available Brainstem pathology due to infections, infarcts and tumors are common in developing countries, but neuroimaging technology in these resource-poor settings is often limited to single slice, and occasionally spiral, CT. Unlike multislice CT and MRI, single slice and spiral CT are compromised by bone artifacts in the posterior fossa due to the dense petrous bones, often making imaging of the brainstem non-diagnostic. With appropriate head positioning, the petrous ridges can be avoided with 40˚ sagittal oblique scans parallel to either petrous ridge. We describe an alternative sagittal oblique scanning technique that significantly reduces brainstem CT artifacts thereby improving clarity of anatomy. With Inst­itutional Ethical approval, 13 adult patients were enrolled (5 males; 39%. All patients had routine axial brain CT and sagittal oblique scans with no lesions found. Images were read by 2 readers who gave a score for amount of artefact and clarity of structures in the posterior fossa. The mean artifact score was higher for routine axial images compared to sagittal oblique (2.92 vs. 1.23; P<0.0001. The mean anatomical certainty scores for the brainstem were significantly better in the sagittal oblique views compared to routine axial (1.23 vs. 2.77; P<0.0001. No difference was found between the two techniques with respect to the fourth ventricle or the cerebellum (axial vs. sag oblique: 1.15 vs. 1.27; P=0.37. When using single slice CT, the sagittal oblique scanning technique is valuable in improving clarity of anatomy in the brainstem if axial images are non-diagnostic due to bone artifacts.

  15. The Influence of Central Corneal Thickness and Corneal Curvature and Axial Length on the Measurement of Intraocular Pressure

    Institute of Scientific and Technical Information of China (English)

    Qing Li; Minru Li; Zhigang Fan; Ningli Wang

    2002-01-01

    Purpose: To examine the influence of central corneal thickness (CCT), corneal curvature (CC), and axial length (AL) on intraocular pressure (IOP).Methods: Eighty-one clinically normal eyes were included in our study. The IOP, CCT, CC, AL were measured using a Goldmann applanation tonometer, optical pachymeter, keratometer and A-scan ultrasound biometer respectively in all subjects.Results: A highly significant positive correlation was identified between IOP and CCT. Linear regression analysis suggests that an increase in CCT of 0. 010 mm is associated with a 4. 946 mmHg increment in IOP. No significant positive correlation was identified between IOP and CC. P values are 0. 724 and 0.414 respectively for vertical and horizontal readings. A paradoxically reversed correlation was present between IOP and axial length.Conclusion: Corneal thickness is a very important confounding factor in the measurement of intraocular pressure, which warrants further attention in our clinical practice.

  16. Computation of the lateral and axial point spread functions in confocal imaging systems using binary amplitude mask

    Indian Academy of Sciences (India)

    A M Hamed

    2006-06-01

    In this paper, a novel aperture based on Tolardo concept composed of a central clear disc surrounded by a series of black and white (B/W) concentric annuli of equal transmittance is presented. Different apodized apertures of different number of B/W annuli are suggested in order to improve further the three-dimensional resolving power of confocal imaging systems. Both the axial and lateral point spread functions (PSF) and the corresponding irradiances are computed in both cases of conventional and confocal scanning microscopes for the above-mentioned amplitude filters. These results of axial and lateral irradiances are graphically represented by constructing a computer program using MATLAB. The obtained results are compared with that obtained in case of circular, annular, and Martinez-Corral apodized aperture.

  17. Surface micromachined scanning mirrors

    DEFF Research Database (Denmark)

    Mattsson, Kent Erik

    1992-01-01

    Both aluminum cantilever and torsional scanning mirrors have been fabricated and their static and dynamic properties are studied experimentally and theoretically. The experiments showed resonance frequencies in the range of 163 k-Hz - 632 kHz for cantilever beams with Q values between 5 and 11....... Torsional mirrors showed resonance frequencies in the range of 410 kHz - 667 kHz with Q values of 10 - 17. All measurements performed at atmospheric pressure. Both types of mechanical structures were deflected electrostatically at large angles (± 5°) more than 1011 times without breaking and without any...

  18. Study on motion artifacts in coronary arteries with an anthropomorphic moving heart phantom on an ECG-gated multidetector computed tomography unit

    NARCIS (Netherlands)

    Greuter, MJW; Dorgelo, J; Tukker, WGJ; Oudkerk, M

    2005-01-01

    Acquisition time plays a key role in the quality of cardiac multi-detector computed tomography (MDCT) and is directly related to the rotation time of the scanner. The purpose of this study is to examine the influence of heart rate and a multisector reconstruction algorithm on the image quality of co

  19. Evaluation of right ventricular volume and mass using retrospective ECG-gated cardiac multidetector computed tomography: comparison with first-pass radionuclide angiography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Hoon [Yonsei University College of Medicine, Department of Radiology, Seoul (Korea); Yongdong Severance Hospital, Department of Radiology, Seoul (Korea); Ryu, Young Hoon; Hur, Jin; Kim, Sang Jin; Kim, Hyun Soo; Choi, Byoung Wook [Yonsei University College of Medicine, Department of Radiology, Seoul (Korea); Kim, Young; Kim, Hyung Jung [Yonsei University College of Medicine, Department of Pulmonology, Seoul (Korea)

    2005-09-01

    The purposes of this study were to evaluate the right ventricular (RV) volume and mass using cardiac multidetector computed tomography (MDCT) and to compare the cardiac MDCT results with those from first-pass radionuclide angiography (FPRA). Twenty patients were evaluated for the RV end-diastolic volume (RVEDV), the RV end-systolic volume (RVESV), the RV ejection fraction (RVEF), and RV mass using cardiac MDCT with a two-phase reconstruction method based on ECG. The end-diastolic phase was reconstructed at the starting point of the QRS complex on ECG, and the end-systolic phase was reconstructed at the halfway point of the ascending T-wave on ECG. The RV mass was measured for the end-systole. The RVEF was also obtained by FPRA. The mean RVEF (47{+-}7%) measured by cardiac MDCT was well correlated with that (44{+-}6%) measured by FPRA (r=0.854). A significant difference in the mean RVEF was found between cardiac MDCT and FPRA (p=0.001), with an overestimation of 2.9{+-}5.3% by cardiac MDCT versus FPRA. The interobserver variability was 4.4% for the RVEDV, 6.8% for the RVESV, and 7.9% for the RV mass, respectively. Cardiac MDCT is relatively simple and allows the RV volume and mass to be assessed, and the RVEF obtained by cardiac MDCT correlates well with that measured by FPRA. (orig.)

  20. ECG-Gated Three-dimensional Intravascular Ultrasound : Feasibility and Reproducibility of the Automated Analysis of Coronary Lumen and Atherosclerotic Plaque Dimensions in Humans

    NARCIS (Netherlands)

    C. von Birgelen (Clemens); E.A. de Vrey (Evelyn); G.S. Mintz (Gary); A. Nicosia; N. Bruining (Nico); W. Li (Wenguang); P.W.J.C. Serruys (Patrick); P.J. de Feyter (Pim); J.R.T.C. Roelandt (Jos); C.J. Slager (Cornelis)

    1997-01-01

    textabstractBackground Automated systems for the quantitative analysis of three-dimensional (3D) sets of intravascular ultrasound (IVUS) images have been developed to reduce the time required to perform volumetric analyses; however, 3D image reconstruction by these nongated systems is frequently

  1. Non-enhanced, ECG-gated MR angiography of the pedal vasculature: comparison with contrast-enhanced MR angiography and digital subtraction angiography in peripheral arterial occlusive disease.

    Science.gov (United States)

    Schubert, Tilman; Takes, Martin; Aschwanden, Markus; Klarhoefer, Markus; Haas, Tanja; Jacob, Augustinus L; Liu, David; Gutzeit, Andreas; Kos, Sebastian

    2016-08-01

    This study was conducted in order to compare a high resolution, non-contrast-enhanced MRA (NATIVE SPACE, NE-MRA) of the pedal vasculature with contrast-enhanced MRA (CE-MRA) and digital subtraction angiography (DSA) in patients with peripheral arterial occlusive disease (PAOD). The prospective study consists of 20 PAOD patients. All patients underwent percutaneous transluminal angioplasty or stenting and received MR angiographies the following day. With CE-MRA, 75.7 % of vessel segments showed good, 16.4 % suboptimal and 7.9 % not usable image quality. With NE-MRA, 64.6 % showed good, 18.6 % suboptimal and 16.8 % not usable image quality. CE-MRA showed a sensitivity and negative predictive value of 90 %/95 % regarding significant stenosis (greater than 50 %), and specificity and positive predictive value were 88 %/77 %. Accordingly, sensitivity and negative predictive value for the NE-MRA were 96 %/97 % and specificity and positive predictive value were 80 %/69 % for stenoses greater than 50 %. The applied NE-MRA technique achieves high diagnostic accuracy even in very small distal arteries of the foot. However, the rate of non-diagnostic vessel segments is considerably higher for NE-MRA than for CE-MRA. NE-MRA is a valuable alternative to CE-MRA in selected patients. • Comparison of non-enhanced MRA with contrast-enhanced MRA and DSA as gold standard. • High resolution MRA at 3 T for the depiction of small pedal vessels. • Evaluation of high resolution non-enhanced MRA in PAOD patients.

  2. Measurement of left ventricular chamber and myocardial volume in hypertrophic cardiomyopathy patients by ECG-gated myocardial perfusion SPECT. Application of a newly developed edge-detection algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Yoshihiro; Katafuchi, Tetsuro; Hirase, Yoshinori; Sagoh, Masayoshi; Oka, Hisashi [National Cardiovascular Center, Suita, Osaka (Japan); Mori, Hideaki [Siemens-Asahi Medical Technologies, Ltd., Tokyo (Japan); Murase, Kenya [Osaka Univ., Suita (Japan). Medical School

    2002-12-01

    Quantitative gated SPECT (QGS) software has been reported to demonstrate inaccurate edge detection in the left ventricular chamber in hypertrophic cardiomyopathy patients. In this study we developed a method to calculate left ventricular volume (LVV) and left myocardial volume (LMV) from gated SPECT data using a newly developed edge-detection algorithm, and we compared it with the QGS method of calculating LVV and LMV in a phantom study. Our method gave more accurate measurements LVV and LMV whereas the QGS method underestimated LMV. Compared with QGS LVV and LMV, our method yielded better results in the phantom study. (author)

  3. Iterative model reconstruction: Improved image quality of low-tube-voltage prospective ECG-gated coronary CT angiography images at 256-slice CT

    Energy Technology Data Exchange (ETDEWEB)

    Oda, Seitaro, E-mail: seisei0430@nifty.com [Department of Cardiology, MedStar Washington Hospital Center, 110 Irving Street, NW, Washington, DC 20010 (United States); Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto, 860-8556 (Japan); Weissman, Gaby, E-mail: Gaby.Weissman@medstar.net [Department of Cardiology, MedStar Washington Hospital Center, 110 Irving Street, NW, Washington, DC 20010 (United States); Vembar, Mani, E-mail: mani.vembar@philips.com [CT Clinical Science, Philips Healthcare, c595 Miner Road, Cleveland, OH 44143 (United States); Weigold, Wm. Guy, E-mail: Guy.Weigold@MedStar.net [Department of Cardiology, MedStar Washington Hospital Center, 110 Irving Street, NW, Washington, DC 20010 (United States)

    2014-08-15

    Objectives: To investigate the effects of a new model-based type of iterative reconstruction (M-IR) technique, the iterative model reconstruction, on image quality of prospectively gated coronary CT angiography (CTA) acquired at low-tube-voltage. Methods: Thirty patients (16 men, 14 women; mean age 52.2 ± 13.2 years) underwent coronary CTA at 100-kVp on a 256-slice CT. Paired image sets were created using 3 types of reconstruction, i.e. filtered back projection (FBP), a hybrid type of iterative reconstruction (H-IR), and M-IR. Quantitative parameters including CT-attenuation, image noise, and contrast-to-noise ratio (CNR) were measured. The visual image quality, i.e. graininess, beam-hardening, vessel sharpness, and overall image quality, was scored on a 5-point scale. Lastly, coronary artery segments were evaluated using a 4-point scale to investigate the assessability of each segment. Results: There was no significant difference in coronary arterial CT attenuation among the 3 reconstruction methods. The mean image noise of FBP, H-IR, and M-IR images was 29.3 ± 9.6, 19.3 ± 6.9, and 12.9 ± 3.3 HU, respectively, there were significant differences for all comparison combinations among the 3 methods (p < 0.01). The CNR of M-IR was significantly better than of FBP and H-IR images (13.5 ± 5.0 [FBP], 20.9 ± 8.9 [H-IR] and 39.3 ± 13.9 [M-IR]; p < 0.01). The visual scores were significantly higher for M-IR than the other images (p < 0.01), and 95.3% of the coronary segments imaged with M-IR were of assessable quality compared with 76.7% of FBP- and 86.9% of H-IR images. Conclusions: M-IR can provide significantly improved qualitative and quantitative image quality in prospectively gated coronary CTA using a low-tube-voltage.

  4. Reproducibility of Abdominal Aortic Aneurysm Diameter Measurement and Growth Evaluation on Axial and Multiplanar Computed Tomography Reformations

    Energy Technology Data Exchange (ETDEWEB)

    Dugas, Alexandre; Therasse, Eric; Kauffmann, Claude; Tang, An [University of Montreal, Department of Radiology, Centre Hospitalier de l' Universite de Montreal (CHUM) and CHUM Research Center (CRCHUM) (Canada); Elkouri, Stephane [University of Montreal, Department of Surgery, Centre Hospitalier de l' Universite de Montreal (CHUM) (Canada); Nozza, Anna [Institut de Cardiologie de Montreal, Montreal Heart Institute Coordinating Centre (Canada); Giroux, Marie-France; Oliva, Vincent L.; Soulez, Gilles, E-mail: gilles.soulez.chum@ssss.gouv.qc.ca [University of Montreal, Department of Radiology, Centre Hospitalier de l' Universite de Montreal (CHUM) and CHUM Research Center (CRCHUM) (Canada)

    2012-08-15

    Purpose: To compare different methods measuring abdominal aortic aneurysm (AAA) maximal diameter (Dmax) and its progression on multidetector computed tomography (MDCT) scan. Materials and Methods: Forty AAA patients with two MDCT scans acquired at different times (baseline and follow-up) were included. Three observers measured AAA diameters by seven different methods: on axial images (anteroposterior, transverse, maximal, and short-axis views) and on multiplanar reformation (MPR) images (coronal, sagittal, and orthogonal views). Diameter measurement and progression were compared over time for the seven methods. Reproducibility of measurement methods was assessed by intraclass correlation coefficient (ICC) and Bland-Altman analysis. Results: Dmax, as measured on axial slices at baseline and follow-up (FU) MDCTs, was greater than that measured using the orthogonal method (p = 0.046 for baseline and 0.028 for FU), whereas Dmax measured with the orthogonal method was greater those using all other measurement methods (p-value range: <0.0001-0.03) but anteroposterior diameter (p = 0.18 baseline and 0.10 FU). The greatest interobserver ICCs were obtained for the orthogonal and transverse methods (0.972) at baseline and for the orthogonal and sagittal MPR images at FU (0.973 and 0.977). Interobserver ICC of the orthogonal method to document AAA progression was greater (ICC = 0.833) than measurements taken on axial images (ICC = 0.662-0.780) and single-plane MPR images (0.772-0.817). Conclusion: AAA Dmax measured on MDCT axial slices overestimates aneurysm size. Diameter as measured by the orthogonal method is more reproducible, especially to document AAA progression.

  5. Electron optics of multi-beam scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi-Gheidari, A., E-mail: A.M.Gheidari@tudelft.nl [Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Kruit, P. [Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands)

    2011-07-21

    We have developed a multi-beam scanning electron microscope (MBSEM), which delivers a square array of 196 focused beams onto a sample with a resolution and current per beam comparable to a state of the art single beam SEM. It consists of a commercially available FEI Nova-nano 200 SEM column equipped with a novel multi-electron beam source module. The key challenge in the electron optical design of the MBSEM is to minimize the off-axial aberrations of the lenses. This article addresses the electron optical design of the system and presents the result of optics simulations for a specific setting of the system. It is shown that it is possible to design a system with a theoretical axial spot size of 1.2 nm at 15 kV with a probe current of 26 pA. The off-axial aberrations for the outermost beam add up 0.8 nm, increasing the probe size to 1.5 nm.

  6. Ultrafast scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Botkin, D.A. [California Univ., Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley Lab., CA (United States)

    1995-09-01

    I have developed an ultrafast scanning tunneling microscope (USTM) based on uniting stroboscopic methods of ultrafast optics and scanned probe microscopy to obtain nanometer spatial resolution and sub-picosecond temporal resolution. USTM increases the achievable time resolution of a STM by more than 6 orders of magnitude; this should enable exploration of mesoscopic and nanometer size systems on time scales corresponding to the period or decay of fundamental excitations. USTM consists of a photoconductive switch with subpicosecond response time in series with the tip of a STM. An optical pulse from a modelocked laser activates the switch to create a gate for the tunneling current, while a second laser pulse on the sample initiates a dynamic process which affects the tunneling current. By sending a large sequence of identical pulse pairs and measuring the average tunnel current as a function of the relative time delay between the pulses in each pair, one can map the time evolution of the surface process. USTM was used to measure the broadband response of the STM`s atomic size tunnel barrier in frequencies from tens to hundreds of GHz. The USTM signal amplitude decays linearly with the tunnel junction conductance, so the spatial resolution of the time-resolved signal is comparable to that of a conventional STM. Geometrical capacitance of the junction does not appear to play an important role in the measurement, but a capacitive effect intimately related to tunneling contributes to the measured signals and may limit the ultimate resolution of the USTM.

  7. An appraisal of golimumab in the treatment of severe, active nonradiographic axial spondyloarthritis

    Directory of Open Access Journals (Sweden)

    Paccou J

    2016-07-01

    Full Text Available Julien Paccou, René-Marc Flipo Department of Rheumatology, Lille University Hospital, Lille, France Abstract: Golimumab (Simponi® is a fully human tumor necrosis factor α inhibitor (TNFi antibody administered subcutaneously. In the European Union, golimumab is indicated for the treatment of adults with severe, active axial spondyloarthritis (axSpA, which includes both ankylosing spondylitis (AS and nonradiographic axSpA (nr-axSpA. In the US, it is indicated for the treatment of adults with active AS only. This article reviews the efficacy and tolerability of golimumab in nr-axSpA patients compared to other TNFi agents (adalimumab, infliximab, etanercept, and certolizumab pegol. In one ongoing, well-designed controlled study (GO-AHEAD, data at 16 weeks showed that treatment with golimumab (50 mg every 4 weeks was effective in improving the clinical signs and symptoms of disease in nr-axSpA patients. In addition, 16 weeks of treatment with golimumab reduced inflammation in the sacroiliac joints and spine in patients with nr-axSpA. Moreover, objective evidence of active inflammation at baseline, such as a positive magnetic resonance imaging scan and/or an elevated CRP level, was a good predictor of treatment response to golimumab. Golimumab was generally well tolerated in this study, with a tolerability profile consistent with that seen in previous clinical trials for other indications. Although additional long-term data are needed, current evidence indicates that golimumab is an effective option for the treatment of nr-axSpA. However, in the absence of comparative head-to-head trials, there is no recommended hierarchy for the first prescription of a TNFi agent for the treatment of either nr-axSpA or AS. Keywords: axial spondyloarthritis, nonradiographic axial spondyloarthritis, ankylosing spondylitis, golimumab, tumor necrosis factor α inhibitor, therapy

  8. Dimensions of the human sclera: Thickness measurement and regional changes with axial length.

    Science.gov (United States)

    Norman, Richard E; Flanagan, John G; Rausch, Sophie M K; Sigal, Ian A; Tertinegg, Inka; Eilaghi, Armin; Portnoy, Sharon; Sled, John G; Ethier, C Ross

    2010-02-01

    Scleral thickness, especially near the region of the optic nerve head (ONH), is a potential factor of interest in the development of glaucomatous optic neuropathy. Our goal was to characterize the scleral thickness distribution and other geometric features of human eyes. Eleven enucleated human globes (7 normal and 4 ostensibly glaucomatous) were imaged using high-field microMRI, providing 80 microm isotropic resolution over the whole eye. The MRI scans were segmented to produce 3-D corneoscleral shells. Each shell was divided into 15 slices along the anterior-posterior axis of the eye, and each slice was further subdivided into the anatomical quadrants. Average thickness was measured in each region, producing 60 thickness measurements per eye. Hierarchical clustering was used to identify trends in the thickness distribution, and scleral geometric features were correlated with globe axial length. Thickness over the whole sclera was 670 +/- 80 microm (mean +/- SD; range: 564 microm-832 microm) over the 11 eyes. Maximum thickness occurred at the posterior pole of the eye, with mean thickness of 996 +/- 181 microm. Thickness decreased to a minimum at the equator, where a mean thickness of 491 +/- 91 microm was measured. Eyes with a reported history of glaucoma were found to have longer axial length, smaller ONH canal dimensions and thinner posterior sclera. Several geometrical parameters of the eye, including posterior scleral thickness, axial length, and ONH canal diameter, appear linked. Significant intra-individual and inter-individual variation in scleral thickness was evident. This may be indicative of inter-individual differences in ocular biomechanics. Copyright 2009 Elsevier Ltd. All rights reserved.

  9. Refraction and the axial length of the eyeball in patients with the optic disc drusen.

    Science.gov (United States)

    Obuchowska, Iwona; Mariak, Zofia

    2009-01-01

    The aim of the study was to demonstrate the relationship between the optic disc drusen (ODD) and the axial length of the eyeball as well as refractive error. We examined prospectively 40 patients with ODD, 18 men and 22 women, age range from 34 to 69 years. All subjects underwent full ophthalmic examination, visual field testing and color-coded duplex sonography of the ocular vessels. Refraction was determined with an autorefractometer (Topcon RM-8000B) and further refined subjectively. Spherical equivalent refraction was calculated as the spherical dioptre plus one half of the cylindrical dioptre. Axial lengths were measured with a Sonomed ultrasound scanner model E-Z Scan AB5500. Clinical signs were observed in 65% of the eyes with drusen, among them, 38% had symptoms of visual acuity loss and all had visual fields defects. There were 21 eyes (18 eyes with and 3 without drusen), with a recorded refractive error. Significant differences in hyperopia were observed between the eyes with and without drusen (p = 0.048). The rate of occurrence of myopia did not differ significantly between affected and unaffected eyes (p = 0.06). The mean spherical equivalent refraction and axial dimensions of the eye differed significantly among the groups of eyes with and without drusen (p < 0.05). Significant differences in mean values of peak-systolic and end-diastolic velocities (p < 0.001) as well as in the resistivity index (p = 0.047) were observed between eyes with and without drusen. The optic disc drusen are often associated with shorter and hyperopic eyes. This anatomical conditions and vascular factors may contribute to pathogenesis of drusen.

  10. Bone Densitometry (Bone Density Scan)

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Bone Densitometry (DEXA) Bone densitometry, also called dual-energy ... limitations of DEXA Bone Densitometry? What is a Bone Density Scan (DEXA)? Bone density scanning, also called ...

  11. Scanned-cantilever atomic force microscope with large scanning range

    Institute of Scientific and Technical Information of China (English)

    Jintao Yang; Wendong Xu

    2006-01-01

    A scanned-cantilever atomic force microscope (AFM) with large scanning range is proposed, which adopts a new design named laser spot tracking. The scanned-cantilever AFM uses the separate flexure x-y scanner and z scanner instead of the conventional piezoelectric tube scanner. The closed-loop control and integrated capacitive sensors of these scanners can insure that the images of samples have excellent linearity and stability. According to the experimental results, the scanned-cantilever AFM can realize maximal 100 × 100 (μm) scanning range, and 1-nm resolution in z direction, which can meet the requirements of large scale sample testing.

  12. Axial length as a risk factor to branch retinal vein occlusion

    NARCIS (Netherlands)

    Timmerman, EA; deLavalette, VWR; vandenBrom, HJB

    1997-01-01

    Purpose: To determine whether axial length is a factor in branch retinal vein occlusion. Methods: Axial length measurements in a group of 24 patients with a unilateral branch retinal Vein occlusion were compared with the axial length measurements in a control group. axial length measurements were ta

  13. Functional CT imaging of the lung in the axial and coronal plane after single-lung transplantation; Computertomographische Funktionsuntersuchung der Lunge nach einseitiger Lungentransplantation mit axialer und koronarer Akquisition

    Energy Technology Data Exchange (ETDEWEB)

    Kauczor, H.U. [Mainz Univ. (Germany). Klinik fuer Radiologie; Buchenroth, M. [Mainz Univ. (Germany). 3. Medizinische Klinik - Pneumologie; Heussel, C.P. [Mainz Univ. (Germany). Klinik fuer Radiologie; Mayer, E. [Mainz Univ. (Germany). Klinik fuer Herz-, Thorax-, Gefaesschirurgie

    1996-05-01

    After single-lung transplantation in a patient suffering from obstructive emphysema lung function parameters worsened during follow-up. To conplement the routine high-resolution CT (HRCT) scans acquired in inspiration, additional scans were obtained to evaluate regional lung function. The comparison of HRCT scans acquired in inspiration and in expiration revealed different ventilation conditions of both lungs, continuous acquisition in a single slice (dynamic multiscan acquisition) in the axial and coronal plane demonstrated mediastinal shifting and the movement of the diaphragm during the whole breathing cycle. Both modalities can provide important information concerning regional differences of ventilation after single-lung transplantation. Expiratory HRCT should be applied on a regular basis in the follow-up of patients after single-lung transplantation. Expiratory HRCT should be applied on a regular basis in the follow-up of patients after single-lung transplantation. The application of axial and coronal dynamic multiscan acquisitions will be helpful in particular clinical conditions, like increasing hyperinflation, mediastinal shifting or bronchial collapse within the region of the anastomosis. (orig.) [Deutsch] Nach Einzellungentransplantation wegen eines obstruktiven Emphysems wurden bei einem Patienten in der Nachsorge zur Abklaerung einer Verschlechterung der Lungenfunktionsparameter neben einer hochaufloesenden CT (HRCT) in Inspiration zusaetzliche Aufnahmen zur Funktionsbeurteilung durchgefuehrt. Der Vergleich von HRCT-Aufnahmen in In- und Exspiration zeigte die unterschiedlichen Ventilationsverhaeltnisse bei beiden Lungen; kontinuierliche Aufnahmen in einer Schicht (Multirotationsaufnahmen) stellten bei axialer und insbesondere bei direkter koronarer Akquisition die Mediastinal- und Zwerchfellbewegung waehrend des gesamten Atemzyklus dar. Beide Verfahren koennen wichtige Zusatzinformationen ueber regionale Ventilationsdifferenzen nach einseitiger

  14. Empirical Correlation of the Morphology of Coiled Carbon Nanotubes with Their Response to Axial Compression

    Directory of Open Access Journals (Sweden)

    Jabulani R. Barber

    2014-01-01

    Full Text Available The mechanical response of thirteen different helical multi-walled carbon nanocoils to axial compression is reported. Each nanocoil was attached to the apex of a cantilever probe tip; its dimensions and orientation relative to the tip apex were determined with scanning electron microscopy. The atomic force microscope was employed to apply a cyclic axial load on the nanocoil. Its mechanical response was determined by simultaneous collection of the thermal resonance frequency, displacement, and oscillation amplitude of the cantilever-nanotube system in real time. Depending upon compression parameters, each coil underwent buckling, bending, and slip-stick motion. Characteristic features in the thermal resonance spectrum and in the force and oscillation amplitude curves for each of these responses to induced stress are presented. Following compression studies, the structure and morphology of each nanocoil were determined by transmission electron microscopy. The compression stiffness of each nanocoil was estimated from the resonant frequency of the cantilever at the point of contact with the substrate surface. From this value, the elastic modulus of the nanocoil was computed and correlated with the coiled carbon nanotube’s morphology.

  15. Characterization of Microstructure and Thermal Properties of YSZ Coatings Obtained by Axial Suspension Plasma Spraying (ASPS)

    Science.gov (United States)

    Ganvir, Ashish; Curry, Nicholas; Björklund, Stefan; Markocsan, Nicolaie; Nylén, Per

    2015-10-01

    The paper aims at demonstrating various microstructures which can be obtained using the suspension spraying technique and their respective significance in enhancing the thermal insulation property of a thermal barrier coating. Three different types of coating microstructures are discussed which were produced by the Axial Suspension Plasma Spraying. Detailed characterization of coatings was then performed. Optical and scanning electron microscopy were utilized for microstructure evaluations; x-ray diffraction for phase analysis; water impregnation, image analysis, and mercury intrusion porosimetry for porosity analysis, and laser flash analysis for thermal diffusivity measurements were used. The results showed that Axial Suspension Plasma Spraying can generate vertically cracked, porous, and feathery columnar-type microstructures. Pore size distribution was found in micron, submicron, and nanometer range. Higher overall porosity, the lower density of vertical cracks or inter-column spacing, and higher inter-pass porosity favored thermal insulation property of the coating. Significant increase in thermal diffusivity and conductivity was found at higher temperature, which is believed to be due to the pore rearrangement (sintering and pore coarsening). Thermal conductivity values for these coatings were also compared with electron beam physical vapor deposition (EBPVD) thermal barrier coatings from the literature and found to be much lower.

  16. Automatic Ultrasound Scanning

    DEFF Research Database (Denmark)

    Moshavegh, Ramin

    Medical ultrasound has been a widely used imaging modality in healthcare platforms for examination, diagnostic purposes, and for real-time guidance during surgery. However, despite the recent advances, medical ultrasound remains the most operator-dependent imaging modality, as it heavily relies...... on the user adjustments on the scanner interface to optimize the scan settings. This explains the huge interest in the subject of this PhD project entitled “AUTOMATIC ULTRASOUND SCANNING”. The key goals of the project have been to develop automated techniques to minimize the unnecessary settings...... on the scanners, and to improve the computer-aided diagnosis (CAD) in ultrasound by introducing new quantitative measures. Thus, four major issues concerning automation of the medical ultrasound are addressed in this PhD project. They touch upon gain adjustments in ultrasound, automatic synthetic aperture image...

  17. Micro scanning probes

    CERN Document Server

    Niblock, T

    2001-01-01

    This thesis covers the design methodology, theory, modelling, fabrication and evaluation of a Micro-Scanning-Probe. The device is a thermally actuated bimorph quadrapod fabricated using Micro Electro Mechanical Systems technology. A quadrapod is a structure with four arms, in this case a planar structure with the four arms forming a cross which is dry etched out of a silicon diaphragm. Each arm has a layer of aluminium deposited on it forming a bimorph. Through heating each arm actuation is achieved in the plane of the quadrapod and the direction normal to it. Fabrication of the device has required the development of bulk micromachining techniques to handle post CMOS fabricated wafers and the patterning of thickly sputtered aluminium in bulk micro machined cavities. CMOS fabrication techniques were used to incorporate diodes onto the quadrapod arms for temperature measurement of the arms. Fine tungsten and silicon tips have also been fabricated to allow tunnelling between the tip and the platform at the centr...

  18. A Scanning Cavity Microscope

    CERN Document Server

    Mader, Matthias; Hänsch, Theodor W; Hunger, David

    2014-01-01

    Imaging of the optical properties of individual nanosystems beyond fluorescence can provide a wealth of information. However, the minute signals for absorption and dispersion are challenging to observe, and only specialized techniques requiring sophisticated noise rejection are available. Here we use signal enhancement in a scanning optical microcavity to demonstrate ultra-sensitive imaging. Harnessing multiple interactions of probe light with a sample within an optical resonator, we achieve a 1700-fold signal enhancement compared to diffraction-limited microscopy. We demonstrate quantitative imaging of the extinction cross section of gold nanoparticles with a sensitivity below 1 nm2, we show a method to improve spatial resolution potentially below the diffraction limit by using higher order cavity modes, and we present measurements of the birefringence and extinction contrast of gold nanorods. The demonstrated simultaneous enhancement of absorptive and dispersive signals promises intriguing potential for opt...

  19. Imaging the p-n junction in a gallium nitride nanowire with a scanning microwave microscope

    Energy Technology Data Exchange (ETDEWEB)

    Imtiaz, Atif [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Wallis, Thomas M.; Brubaker, Matt D.; Blanchard, Paul T.; Bertness, Kris A.; Sanford, Norman A.; Kabos, Pavel, E-mail: kabos@boulder.nist.gov [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Weber, Joel C. [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Coakley, Kevin J. [Information Technology Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)

    2014-06-30

    We used a broadband, atomic-force-microscope-based, scanning microwave microscope (SMM) to probe the axial dependence of the charge depletion in a p-n junction within a gallium nitride nanowire (NW). SMM enables the visualization of the p-n junction location without the need to make patterned electrical contacts to the NW. Spatially resolved measurements of S{sub 11}{sup ′}, which is the derivative of the RF reflection coefficient S{sub 11} with respect to voltage, varied strongly when probing axially along the NW and across the p-n junction. The axial variation in S{sub 11}{sup ′}  effectively mapped the asymmetric depletion arising from the doping concentrations on either side of the junction. Furthermore, variation of the probe tip voltage altered the apparent extent of features associated with the p-n junction in S{sub 11}{sup ′} images.

  20. Development and Testing of an Axial Halbach Magnetic Bearing

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2006-01-01

    The NASA Glenn Research Center has developed and tested a revolutionary Axial Halbach Magnetic Bearing. The objective of this work is to develop a viable non-contact magnetic thrust bearing utilizing Halbach arrays for all-electric flight, and many other applications. This concept will help to reduce harmful emissions, reduce the Nation s dependence on fossil fuels and mitigate many of the concerns and limitations encountered in conventional axial bearings such as bearing wear, leaks, seals and friction loss. The Axial Halbach Magnetic Bearing is inherently stable and requires no active feedback control system or superconductivity as required in many magnetic bearing designs. The Axial Halbach Magnetic Bearing is useful for very high speed applications including turbines, instrumentation, medical systems, computer memory systems, and space power systems such as flywheels. Magnetic fields suspend and support a rotor assembly within a stator. Advanced technologies developed for particle accelerators, and currently under development for maglev trains and rocket launchers, served as the basis for this application. Experimental hardware was successfully designed and developed to validate the basic principles and analyses. The report concludes that the implementation of Axial Halbach Magnetic Bearings can provide significant improvements in rotational system performance and reliability.

  1. Method to measure tone of axial and proximal muscle.

    Science.gov (United States)

    Gurfinkel, Victor S; Cacciatore, Timothy W; Cordo, Paul J; Horak, Fay B

    2011-12-14

    The control of tonic muscular activity remains poorly understood. While abnormal tone is commonly assessed clinically by measuring the passive resistance of relaxed limbs, no systems are available to study tonic muscle control in a natural, active state of antigravity support. We have developed a device (Twister) to study tonic regulation of axial and proximal muscles during active postural maintenance (i.e. postural tone). Twister rotates axial body regions relative to each other about the vertical axis during stance, so as to twist the neck, trunk or hip regions. This twisting imposes length changes on axial muscles without changing the body's relationship to gravity. Because Twister does not provide postural support, tone must be regulated to counteract gravitational torques. We quantify this tonic regulation by the restive torque to twisting, which reflects the state of all muscles undergoing length changes, as well as by electromyography of relevant muscles. Because tone is characterized by long-lasting low-level muscle activity, tonic control is studied with slow movements that produce "tonic" changes in muscle length, without evoking fast "phasic" responses. Twister can be reconfigured to study various aspects of muscle tone, such as co-contraction, tonic modulation to postural changes, tonic interactions across body segments, as well as perceptual thresholds to slow axial rotation. Twister can also be used to provide a quantitative measurement of the effects of disease on axial and proximal postural tone and assess the efficacy of intervention.

  2. Design and Simulation of Axial Flow Maglev Blood Pump

    Directory of Open Access Journals (Sweden)

    Huachun Wu

    2011-03-01

    Full Text Available The axial flow maglev blood pump (AFMBP has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, compact structure and light weight, can effectively solve thrombus and hemolysis. Magnetic suspension and impeller is two of the important parts in the axial flow maglev blood pump, and their structure largely determines the blood pump performance. The research adopts electromagnetic and fluid finite element analysis, and puts forward a method to design the magnetic suspension and impeller of axial flow blood pump, which tacks into account the small volume of axial blood pump. The magnetic bearing’s characteristics are evaluated by electromagnetic finite element analysis. The Blades have been designed by calculating aerofoil bone line, and make simulation analysis for different thicken ways of blade by Fluent software, and make a conclusion that the blade thickened with certain rules has better characteristics in the same conditions. The results will provide some guidance for design of axial flow maglev blood pump, and establish theoretical basis for application of the implantable artificial heart pump.

  3. Light weakly coupled axial forces: models, constraints, and projections

    Science.gov (United States)

    Kahn, Yonatan; Krnjaic, Gordan; Mishra-Sharma, Siddharth; Tait, Tim M. P.

    2017-05-01

    We investigate the landscape of constraints on MeV-GeV scale, hidden U(1) forces with nonzero axial-vector couplings to Standard Model fermions. While the purely vector-coupled dark photon, which may arise from kinetic mixing, is a well-motivated scenario, several MeV-scale anomalies motivate a theory with axial couplings which can be UV-completed consistent with Standard Model gauge invariance. Moreover, existing constraints on dark photons depend on products of various combinations of axial and vector couplings, making it difficult to isolate the effects of axial couplings for particular flavors of SM fermions. We present a representative renormalizable, UV-complete model of a dark photon with adjustable axial and vector couplings, discuss its general features, and show how some UV constraints may be relaxed in a model with nonrenormalizable Yukawa couplings at the expense of fine-tuning. We survey the existing parameter space and the projected reach of planned experiments, briefly commenting on the relevance of the allowed parameter space to low-energy anomalies in π0 and 8Be∗ decay.

  4. An Axial Vector Photon in a Mirror World

    CERN Document Server

    Sharafiddinov, Rasulkhozha S

    2015-01-01

    The unity of symmetry laws emphasizes, in the case of a mirror CP-even Dirac Lagrangian, the ideas of the left- and right-handed axial-vector photons referring to long- and short-lived bosons of true neutrality, respectively. Such a difference in lifetimes expresses the unidenticality of masses, energies and momenta of axial-vector photons of the different components. They define the unified field theory equation of C-odd particles with an integral spin. Together with a new equation of a theory of truly neutral particles with the half-integral spin, the latter reflects the availability in their nature of the second type of the local axial-vector gauge transformation responsible for origination in the Lagrangian of C-oddity of an interaction Newton component giving an axial-vector mass to all the interacting particles and fields. The mirror axial-vector mass, energy and momentum operators constitute a CP-invariant equation of quantum mechanics, confirming that each of them can individually influence on matter ...

  5. Light Weakly Coupled Axial Forces: Models, Constraints, and Projections

    CERN Document Server

    Kahn, Yonatan; Mishra-Sharma, Siddharth; Tait, Tim M P

    2016-01-01

    We investigate the landscape of constraints on MeV-GeV scale, hidden U(1) forces with nonzero axial-vector couplings to Standard Model fermions. While the purely vector-coupled dark photon, which may arise from kinetic mixing, is a well-motivated scenario, several MeV-scale anomalies motivate a theory with axial couplings which can be UV-completed consistent with Standard Model gauge invariance. Moreover, existing constraints on dark photons depend on products of various combinations of axial and vector couplings, making it difficult to isolate the effects of axial couplings for particular flavors of SM fermions. We present a representative renormalizable, UV-complete model of a dark photon with adjustable axial and vector couplings, discuss its general features, and show how some UV constraints may be relaxed in a model with nonrenormalizable Yukawa couplings at the expense of fine-tuning. We survey the existing parameter space and the projected reach of planned experiments, briefly commenting on the relevan...

  6. Light Weakly Coupled Axial Forces: Models, Constraints, and Projections

    Energy Technology Data Exchange (ETDEWEB)

    Kahn, Yonatan [Princeton U.; Krnjaic, Gordan [Fermilab; Mishra-Sharma, Siddharth [Princeton U.; Tait, Tim P. [UC, Irvine

    2016-09-28

    We investigate the landscape of constraints on MeV-GeV scale, hidden U(1) forces with nonzero axial-vector couplings to Standard Model fermions. While the purely vector-coupled dark photon, which may arise from kinetic mixing, is a well-motivated scenario, several MeV-scale anomalies motivate a theory with axial couplings which can be UV-completed consistent with Standard Model gauge invariance. Moreover, existing constraints on dark photons depend on products of various combinations of axial and vector couplings, making it difficult to isolate the effects of axial couplings for particular flavors of SM fermions. We present a representative renormalizable, UV-complete model of a dark photon with adjustable axial and vector couplings, discuss its general features, and show how some UV constraints may be relaxed in a model with nonrenormalizable Yukawa couplings at the expense of fine-tuning. We survey the existing parameter space and the projected reach of planned experiments, briefly commenting on the relevance of the allowed parameter space to low-energy anomalies in pi^0 and 8-Be* decay.

  7. Amphiregulin Antibody and Reduction of Axial Elongation in Experimental Myopia

    Directory of Open Access Journals (Sweden)

    Wen Jun Jiang

    2017-03-01

    Full Text Available To examine the mechanism of ocular axial elongation in myopia, guinea pigs (age: 2–3 weeks which either underwent unilateral or bilateral lens-induced myopization (group 1 or which were primarily myopic at baseline (group 2 received unilateral intraocular injections of amphiregulin antibody (doses: 5, 10, or 15 μg three times in intervals of 9 days. A third group of emmetropic guinea pigs got intraocular unilateral injections of amphiregulin (doses: 0.25, 0.50 or 1.00 ng, respectively. In each group, the contralateral eyes received intraocular injections of Ringer's solution. In intra-animal inter-eye comparison and intra-eye follow-up comparison in groups 1 and 2, the study eyes as compared to the contralateral eyes showed a dose-dependent reduction in axial elongation. In group 3, study eyes and control eyes did not differ significantly in axial elongation. Immunohistochemistry revealed amphiregulin labelling at the retinal pigment epithelium in eyes with lens-induced myopization and Ringer's solution injection, but not in eyes with amphiregulin antibody injection. Intraocular injections of amphiregulin-antibody led to a reduction of lens-induced axial myopic elongation and of the physiological eye enlargement in young guinea pigs. In contrast, intraocularly injected amphiregulin in a dose of ≤1 ng did not show a significant effect. Amphiregulin may be one of several essential molecular factors for axial elongation.

  8. Axial clamp for nuclear reactor head penetration conoseal joints

    Energy Technology Data Exchange (ETDEWEB)

    Hackley, T.A.

    1987-03-31

    A method is described for forming a sealed coupling between two bodies, each body presenting an annular abutment surface. The respective bodies are arranged so that their respective annular abutment surfaces are axially adjacent one another, defining a space therebetween, wherein a deformable gasket is disposed within the space. The method comprises: providing one of the bodies with an annular projection; providing the other body with threads for receiving an annular locknut which can be tightened to bear against the annular projection of the one body; applying an external axial forced to the bodies for compressing the abutment surfaces together against the gasket to form a seal between the bodies; immobilizing the bodies relative to one another while the external force is being applied to the bodies by hand-tightening an annular locknut via the threads of the other body until the locknut abuts the annular projection of the one body, substantially preventing relative axial movement between the bodies when the external axial force is withdrawn; and withdrawing the external axial force applied to the bodies, leaving the two bodies coupled together via the seal.

  9. An Axial-Vector Photon in a Mirror World

    Science.gov (United States)

    Sharafiddinov, Rasulkhozha S.

    2016-03-01

    The unity of symmetry laws emphasizes, in the case of a mirror CP-even Dirac Lagrangian, the ideas of the left- and right-handed axial-vector photons referring to long- and short-lived bosons of true neutrality, respectively. Such a difference in lifetimes expresses the unidenticality of masses, energies and momenta of axial-vector photons of the different components. They define the unified field theory equation of C-odd particles with an integral spin. Together with a new equation of a theory of truly neutral particles with the half-integral spin, the latter reflects the availability in their nature of the second type of the local axial-vector gauge transformation responsible for origination in the Lagrangian of C-oddity of an interaction Newton component giving an axial-vector mass to all the interacting particles and fields. The mirror axial-vector mass, energy and momentum operators constitute a CP-invariant equation of quantum mechanics, confirming that each of them can individually influence on matter field. Thereby, findings suggest at the level of the mass-charge structure of gauge invariance a new equation for the C-noninvariant Lagrangian.

  10. Bladder tumors:dynamic contrast-enhanced axial imaging, multiplanar reformation, three-dimensional reconstruction and virtual cystoscopy using helical CT

    Institute of Scientific and Technical Information of China (English)

    王东; 张挽时; 熊明辉; 喻敏; 徐家兴

    2004-01-01

    Background There have been few studies to evaluate the effects of helical CT on bladder tumor. This study was to evaluate the clinical applications of helical CT dynamic contrast-enhanced axial imaging, multiplanar reformation (MPR), three-dimensional (3D) reconstruction and virtual cystoscopy (CTVC) in bladder tumors. Methods The precontrast and four-phase postcontrast helical CT scans were performed in 42 patients with bladder tumors confirmed by conventional cystoscopy and pathology. MPR, 3D and CTVC images were generated from the volumetric data of the excretory phase. The results were then compared with the findings of conventional cystoscopy and surgery in a double-blinded mode. Results The sensitivity of the axial, 3D and CTVC images in detecting the bladder tumors were 90.8%, 76.9% and 95.4% respectively. The dynamic contrast-enhanced axial images could provide excellent intramural and extravesical information, and the accuracy in preoperative tumor staging was 87.7%. MPR could directly demonstrate the origin and extravesical invasions of the tumors and their relation to the ureter. 3D and CTVC images were useful for displaying the surface morphology of the tumor and the relationship between the tumor and the ureteric orifices, whereas CTVC could depict the tumors smaller than 5 mm that were not seen on the axial images.Conclusions The combination of axial, MPR, 3D and CTVC images with helical CT can provide comprehensive information on bladder tumor.

  11. Study of the Edge-on Self-Assembly of Axially Substituted Silicon(IV) Phthalocyanine Derivatives in a Template on the HOPG Surface.

    Science.gov (United States)

    Geng, Yanfang; Xu, Jing; Xue, Jindong; Shen, Xiaomin; Li, Min; Huang, Jiandong; Li, Xiaokang; Zeng, Qingdao

    2015-12-15

    Molecular conformation is an important issue related to the self-assembly architecture and property. The self-assembly of silicon(IV) phthalocyanines covalently linked to the 5-N-cytidine or 4-carboxyphenoxy moiety at the axial positions, namely, SiPc(NC)2 and SiPc(CP)2, respectively, has been studied by means of scanning tunneling microscopy (STM) at the solid-liquid interface. The intermolecular axial hydrogen bonding in combination with the stabilizing role of the TCDB template brings about supramolecular self-assembled structures of silicon(IV) phthalocyanines in an edge-on orientation. Two pyridine compounds, 4,4'-bipyridine (BPY) and 1,2-di(4-pyridyl)ethylene (DPE), can tune the supramolecular structure, leading to interestingly axial self-assemblies of SiPc(CP)2 with BPY and DPE in an edge-on manner by hydrogen bonding. The results indicate that the axial substituents and the axial ligands can regulate and precisely control the conformation and arrangement of the phthalocyanine moiety on the graphite surface.

  12. Dynamic Behavior of Axially Functionally Graded Pipes Conveying Fluid

    Directory of Open Access Journals (Sweden)

    Chen An

    2017-01-01

    Full Text Available Dynamic behavior of axially functionally graded (FG pipes conveying fluid was investigated numerically by using the generalized integral transform technique (GITT. The transverse vibration equation was integral transformed into a coupled system of second-order differential equations in the temporal variable. The Mathematica’s built-in function, NDSolve, was employed to numerically solve the resulting transformed ODE system. Excellent convergence of the proposed eigenfunction expansions was demonstrated for calculating the transverse displacement at various points of axially FG pipes conveying fluid. The proposed approach was verified by comparing the obtained results with the available solutions reported in the literature. Moreover, parametric studies were performed to analyze the effects of Young’s modulus variation, material distribution, and flow velocity on the dynamic behavior of axially FG pipes conveying fluid.

  13. Bistability between equatorial and axial dipoles during magnetic field reversals

    CERN Document Server

    Gissinger, Christophe; Schrinner, Martin; Dormy, Emmanuel

    2012-01-01

    Numerical simulations of the geodynamo in presence of an heterogeneous heating are presented. We study the dynamics and the structure of the magnetic field when the equatorial symmetry of the flow is broken. If the symmetry breaking is sufficiently strong, the m = 0 axial dipolar field is replaced by an hemispherical magnetic field, dominated by an oscillating m = 1 magnetic field. Moreover, for moderate symmetry breaking, a bistability between the axial and the equatorial dipole is observed. In this bistable regime, the axial magnetic field exhibits chaotic switches of its polarity, involving the equatorial dipole during the transition period. This new scenario for magnetic field reversals is discussed within the framework of the Earth's dynamo.

  14. Bistability between equatorial and axial dipoles during magnetic field reversals.

    Science.gov (United States)

    Gissinger, Christophe; Petitdemange, Ludovic; Schrinner, Martin; Dormy, Emmanuel

    2012-06-08

    Numerical simulations of the geodynamo in the presence of heterogeneous heating are presented. We study the dynamics and the structure of the magnetic field when the equatorial symmetry of the flow is broken. If the symmetry breaking is sufficiently strong, the m=0 axial dipolar field is replaced by a hemispherical magnetic field, dominated by an oscillating m=1 magnetic field. Moreover, for moderate symmetry breaking, a bistability between the axial and the equatorial dipole is observed. In this bistable regime, the axial magnetic field exhibits chaotic switches of its polarity, involving the equatorial dipole during the transition period. This new scenario for magnetic field reversals is discussed within the framework of Earth's dynamo.

  15. Numerical analysis of cavitation within slanted axial-flow pump

    Institute of Scientific and Technical Information of China (English)

    张睿; 陈红勋

    2013-01-01

    In this paper, the cavitating flow within a slanted axial-flow pump is numerically researched. The hydraulic and cavitation performance of the slanted axial-flow pump under different operation conditions are estimated. Compared with the experimental hydraulic performance curves, the numerical results show that the filter-based model is better than the standard k-e model to predict the parameters of hydraulic performance. In cavitation simulation, compared with the experimental results, the proposed numerical method has good predicting ability. Under different cavitation conditions, the internal cavitating flow fields within slanted axial-flow pump are investigated. Compared with flow visualization results, the major internal flow features can be effectively grasped. In order to explore the origin of the cavitation performance breakdown, the Boundary Vorticity Flux (BVF) is introduced to diagnose the cavitating flow fields. The analysis results indicate that the cavitation performance drop is relevant to the instability of cavitating flow on the blade suction surface.

  16. Unsteady cooperative flow type in the axial compressor

    Institute of Scientific and Technical Information of China (English)

    ZHENG Xinqian; ZHOU Sheng; HOU Anping; XIONG Jinsong

    2005-01-01

    For increasing the performance of the axial compressor, a method for realizing unsteady cooperative flow type is proposed in this paper as a critical objective in the new generation of the axial compressor design system. Unsteady excitations were utilized to trigger the transformation from the unsteady natural flow pattern into the unsteady cooperative flow pattern, resulting in increment of aerodynamic performances of axial compressor. Numerical simulations show that distinct positive effect can be obtained for the 2D cascade in a wide range of subsonic working conditions. No positive effect can be observed under the 2D supersonic working conditions and unsteady excitations have little influence on the flow field space-time structure. However, positive effect can be obtained under the 3D transsonic working conditions. In addition, engineering applications of unsteady cooperative flow type are discussed.

  17. Investigation of Aluminum-Copper Tube Hydroforming with Axial Feeding

    Science.gov (United States)

    Parto D., M.; Seyedkashi, S. M. H.; Liaghat, Gh.; Naeini, H. Moslemi; Panahizadeh R., V.

    2011-01-01

    Hydroforming of a two-layered Aluminum-Copper tube is investigated numerically and experimentally. Pressure is applied through a nonlinear path along with symmetrical axial feeding. ABAQUS/Explicit commercial code is used for finite element simulation of the process. ASTM C11000 Copper alloy is used as inner layer and ASTM AA1050A Aluminum alloy is used as outer layer. The simulation results show that the part can be successfully formed under internal pressure of 40 MPa with 8 mm axial displacement. Stress distributions on both inner and outer tubes are compared and maximum thinning on their wall is also discussed. Different friction conditions are applied on the process using different coefficients of friction and their effects are investigated on thinning percentage of inner and outer tubes and also on axial feeding. It is observed that finite element results are in good agreement with experimental results.

  18. Ball Screw Actuator Including an Axial Soft Stop

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Forrest, Steven Talbert (Inventor); Abel, Steve (Inventor); Woessner, George (Inventor); Hanlon, Casey (Inventor)

    2016-01-01

    An actuator includes an actuator housing, a ball screw, and an axial soft stop assembly. The ball screw extends through the actuator housing and has a first end and a second end. The ball screw is coupled to receive a drive force and is configured, upon receipt of the drive force, to selectively move in a retract direction and an extend direction. The axial soft stop assembly is disposed within the actuator housing. The axial soft stop assembly is configured to be selectively engaged by the ball screw and, upon being engaged thereby, to translate, with compliance, a predetermined distance in the extend direction, and to prevent further movement of the ball screw upon translating the predetermined distance.

  19. Liquid Axial Mixing in Packed Tower at Elevated Pressure

    Institute of Scientific and Technical Information of China (English)

    唐忠利; 张鹏; 等

    2003-01-01

    Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m,in which the structured packing,Mellapak 350Y,was installed.Tap water as the liquid phase flowed down through the column and stagnant gas was at elevated pressure ranging from atmospheric to 2.0MPa.The model parameters of Bo andθwere estimated with the least square method in the time domain.As liquid flow rate was increased,the liquid axial mixing decreased.under our experimental conditions,the effect of pressure on Bo number on single liquid phase was negligible,and eddy diffusion was believed to be the primary cause of axial mixing in liquid phase.

  20. Early brain enlargement and elevated extra-axial fluid in infants who develop autism spectrum disorder.

    Science.gov (United States)

    Shen, Mark D; Nordahl, Christine W; Young, Gregory S; Wootton-Gorges, Sandra L; Lee, Aaron; Liston, Sarah E; Harrington, Kayla R; Ozonoff, Sally; Amaral, David G

    2013-09-01

    Prospective studies of infants at risk for autism spectrum disorder have provided important clues about the early behavioural symptoms of autism spectrum disorder. Diagnosis of autism spectrum disorder, however, is not currently made until at least 18 months of age. There is substantially less research on potential brain-based differences in the period between 6 and 12 months of age. Our objective in the current study was to use magnetic resonance imaging to identify any consistently observable brain anomalies in 6-9 month old infants who would later develop autism spectrum disorder. We conducted a prospective infant sibling study with longitudinal magnetic resonance imaging scans at three time points (6-9, 12-15, and 18-24 months of age), in conjunction with intensive behavioural assessments. Fifty-five infants (33 'high-risk' infants having an older sibling with autism spectrum disorder and 22 'low-risk' infants having no relatives with autism spectrum disorder) were imaged at 6-9 months; 43 of these (27 high-risk and 16 low-risk) were imaged at 12-15 months; and 42 (26 high-risk and 16 low-risk) were imaged again at 18-24 months. Infants were classified as meeting criteria for autism spectrum disorder, other developmental delays, or typical development at 24 months or later (mean age at outcome: 32.5 months). Compared with the other two groups, infants who developed autism spectrum disorder (n = 10) had significantly greater extra-axial fluid at 6-9 months, which persisted and remained elevated at 12-15 and 18-24 months. Extra-axial fluid is characterized by excessive cerebrospinal fluid in the subarachnoid space, particularly over the frontal lobes. The amount of extra-axial fluid detected as early as 6 months was predictive of more severe autism spectrum disorder symptoms at the time of outcome. Infants who developed autism spectrum disorder also had significantly larger total cerebral volumes at both 12-15 and 18-24 months of age. This is the first magnetic

  1. Regional brain axial and radial diffusivity changes during development.

    Science.gov (United States)

    Kumar, Rajesh; Nguyen, Haidang D; Macey, Paul M; Woo, Mary A; Harper, Ronald M

    2012-02-01

    The developing human brain shows rapid myelination and axonal changes during childhood, adolescence, and early adulthood, requiring successive evaluations to determine normative values for potential pathological assessment. Fiber characteristics can be examined by axial and radial diffusivity procedures, which measure water diffusion parallel and perpendicular to axons and show primarily axonal status and myelin changes, respectively. Such measures are lacking from widespread sites for the developing brain. Diffusion tensor imaging data were acquired from 30 healthy subjects (age 17.7 ± 4.6 years, range 8-24 years, body mass index 21.5 ± 4.5 kg/m(2), 18 males) using a 3.0-Tesla MRI scanner. Diffusion tensors were calculated, principal eigenvalues determined, and axial and radial diffusivity maps calculated and normalized to a common space. A set of regions of interest was outlined from widespread brain areas within rostral, thalamic, hypothalamic, cerebellar, and pontine regions, and average diffusivity values were calculated using normalized diffusivity maps and these regions of interest masks. Age-related changes were assessed with Pearson's correlations, and gender differences evaluated with Student's t-tests. Axial and radial diffusivity values declined with age in the majority of brain areas, except for midhippocampus, where axial diffusivity values correlated positively with age. Gender differences emerged within putamen, thalamic, hypothalamic, cerebellar, limbic, temporal, and other cortical sites. Documentation of normal axial and radial diffusivity values will help assess disease-related tissue changes. Axial and radial diffusivities change with age,with fiber structure and organization differing between sexes in several brain areas. The findings may underlie gender-based functional characteristics, and mandate partitioning age- and gender-related changes during developmental brain pathology evaluation.

  2. Instability of Meridional Axial System in f(R) Gravity

    CERN Document Server

    Sharif, M

    2015-01-01

    We analyze dynamical instability of non-static reflection axial stellar structure by taking into account generalized Euler's equation in metric $f(R)$ gravity. Such an equation is obtained by contracting Bianchi identities of usual anisotropic and effective stress-energy tensors, which after using radial perturbation technique gives modified collapse equation. In the realm of $R+\\epsilon R^n$ gravity model, we investigate instability constraints at Newtonian and post-Newtonian approximations. We find that instability of meridional axial self-gravitating system depends upon static profile of structure coefficients while $f(R)$ extra curvature terms induce stability to the evolving celestial body.

  3. Vector and Axial Currents in Wilson Chiral Perturbation Theory

    CERN Document Server

    Aoki, Sinya; Sharpe, Stephen R

    2009-01-01

    We reconsider the construction of the vector and axial-vector currents in Wilson Chiral Perturbation Theory (WChPT), the low-energy effective theory for lattice QCD with Wilson fermions. We discuss in detail the finite renormalization of the currents that has to be taken into account in order to properly match the currents. We explicitly show that imposing the chiral Ward identities on the currents does, in general, affect the axial-vector current at O(a). As an application of our results we compute the pion decay constant to one loop in the two flavor theory. Our result differs from previously published ones.

  4. Buckling localization in a cylindrical panel under axial compression

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Needleman, A.

    2000-01-01

    Localization of an initially periodic buckling pattern is investigated for an axially compressed elastic-plastic cylindrical panel of the type occurring between axial stiffeners on cylindrical shells. The phenomenon of buckling localization and its analogy with plastic flow localization in tensile...... test specimens is discussed in general. For the cylindrical panel, it is shown that buckling localization develops shortly after a maximum load has been attained, and this occurs for a purely elastic panel as well as for elastic-plastic panels. In a case where localization occurs after a load maximum...

  5. Self-collimated axial jets from thin accretion disks

    CERN Document Server

    Tirabassi, Giulio; Carlevaro, Nakia; Benini, Riccardo

    2012-01-01

    We show how an appropriate stationary crystalline structure of the magnetic field can induce a partial fragmentation of the accretion disk, generating an axial jet composed of hot rising plasma twisted in a funnel-like structure by the rotation of the system. The most important feature of the obtained jet is its high degree of collimation, naturally arising from the condition for its existence. The presence of non-zero dissipative effects allows the plasma ejection throughout the axial jet and the predicted values of the accretion rate are in agreement with observations.

  6. Spectral analysis in thin tubes with axial heterogeneities

    KAUST Repository

    Ferreira, Rita

    2015-01-01

    In this paper, we present the 3D-1D asymptotic analysis of the Dirichlet spectral problem associated with an elliptic operator with axial periodic heterogeneities. We extend to the 3D-1D case previous 3D-2D results (see [10]) and we analyze the special case where the scale of thickness is much smaller than the scale of the heterogeneities and the planar coefficient has a unique global minimum in the periodic cell. These results are of great relevance in the comprehension of the wave propagation in nanowires showing axial heterogeneities (see [17]).

  7. An effective theory for QCD with an axial chemical potential

    CERN Document Server

    Andrianov, Alexander A; Espriu, Domenec; Planells, Xumeu

    2013-01-01

    We consider the low energy realization of QCD in terms of meson fields when an axial chemical potential is present; a situation that may be relevant in heavy ion collisions. We shall demonstrate that the presence of an axial charge constitutes an explicit source of parity breaking. The eigenstates of strong interactions do not have a definite parity and interactions that would otherwise be forbidden compete with the familiar ones. In this work, we first focus on scalars and pseudoscalars that are described by a generalized linear sigma model; and next, we give some hints on how the Vector Meson Dominance model describes the vector sector.

  8. Fermion decoupling and the axial anomaly on the lattice

    CERN Document Server

    Banerjee, H; De, Asit K.

    1999-01-01

    By an explicit calculation of the continuum limit of the triangle graph amplitude in lattice QED we show that in the axial Ward identity the ABJ anomaly exactly cancels the pseudoscalar density term in the limit of infinite fermion mass $m$. The result, a reflection of decoupling of the heavy fermion, provides a convenient framework for computing the flavor-singlet or U(1) axial anomaly in non-Abelian gauge theories on lattice. Our calculations on the lattice are performed using Wilson fermions but the results are general.

  9. The axial topographic high at intermediate and fast spreading ridges

    Science.gov (United States)

    Carbotte, Suzanne M.; MacDonald, Ken C.

    1994-12-01

    An axial topographic high is commonly observed at both fast spreading ridges and some segments of intermediate spreading ridges. At fast rates the axial high is primarily created by the buoyancy of hot rock and magma beneath the rise. As newly formed crust is transported off axis, little vestige of an axial high is observed on the ridge flanks. In contrast, at intermediate rates, a significant component of the positive topography may be a volcanic construction, preserved on the ridge flanks as abyssal hills, which are slit axial volcanoes. We suggest this difference in the nature of the axial high reflects a lithosphere strong enough to support construction of a volcanic crestal ridge at intermediate spreading rates, but only rarely at fast rates. Relict overlap ridges, found within the discordant zones left by overlapping spreading centers, is one class of ridge-flank topography which appears to have a significant volcanic constructional component even at fast spreading ridges. Unlike topography away from these discontinuities, the relief and shape of overlapping spreading centers is preserved as relict ridge tips are rafted onto the ridge flanks. Reduced magma supply at these discontinuities may give rise to an axial lithosphere strong enough to support volcanic construction of overlap ridges. Low axial lithospheric strength may also account for the lack of normal faults within the innermost 1-2 km of fast, and some intermediate, spreading ridges. With a thin/weak brittle layer at the ridge crest, tensile failure will predominate and few normal faults will form. Depths to the axial magma chamber reflector observed in multi-channel seismic data limit the thickness of the brittel layer on axis to less than 1-2 km for much of the East Pacific Rise (EPR). This depth is comparable to depths over which tensile failure within the oceanic crust will predominate, estimated from the Griffith criteria for fracture initiation (approx. 0.5-1.5 km). As the brittle layer

  10. Recent Results on High-Pressure Axial Blowers

    Science.gov (United States)

    Eckert, B.

    1947-01-01

    Considerable progress has, in recent times, been attained in the development of the high-pressure axial blower by well-planned research. The efforts are directed toward improving the efficiencies, which are already high for the axial blower, and in particular the delivery pressure heads. For high pressures multistage arrangements are used. Of fundamental importance is the careful design of all structural parts of the blower that are subject to the effects of the flow. In the present report, several recent results and experiences are reported, which are based on results of German engine research.

  11. The seismic design of axial blower using Ansys

    Energy Technology Data Exchange (ETDEWEB)

    Im, Hyung Bin; Kim, Kang Sung; Heo, Jin Wook; Chung, Jin Tai [Hanyang Univ., Seoul (Korea, Republic of)

    2001-07-01

    The seismic design for an axial blower is the procedure in which the Required Response Spectrum(RRS) is computed by using the Floor Response Spectrum(FRS). The seismic design is very important to reduce severe damages from an earthquake; therefore, the seismic design has been a great concern in engineering society. In this study, after finite element modeling is established by using Ansys, the modal data are obtained such as the natural frequencies, the participation factor, and so on. With these data, the RRS is acquired by a numerical approach. The seismic safety of the axial blower is evaluated.

  12. MR Cholangiography: Axial TSE-T2 Sequence Evaluation in the Diagnosis of Choledocholithiasis; Colangiografia RM: evaluacion de la secuencia TSE-T2 axial en la deteccion de coledocolitiasis

    Energy Technology Data Exchange (ETDEWEB)

    Alustiza, J. M.; Gervas, C.; Garcia, E.; Recondo, J. A. [Hospital Donostia. San Sebastian (Spain)

    2003-07-01

    To evaluate diagnostic precision of the axial TSE-T2 sequence in the diagnosis of choledocholithiasis. Retrospective analysis of all those MR cholangiography studies performed in our center between January 1998 and June 1999 which were later subjected to conventional cholangiography (intraoperative) as a golden standard. A total of 39 patients was studied. Imaging parameters of the sequence evaluated, fat-suppressed TSE-T2 in the axial plane, were as follows: TE 100 ms, TR 1.800 ms, turbo factor 23 FOV 375 mm, NSA 4, 228 x 256 matrix, respiratory compensation, number of slices 35, slice thickness 3 mm, contiguous slices, scan duration 5'4''. Without having been informed as to the cholangiography result, two radiologists independently analyzed this sequence in order to determine the presence of choledocholithiasis. Their results were latter compared with those of the conventional cholangiography. The sensitivity, specificity and agreement between results were all calculated. 21 patients had choledocholithiasis. The analyzed sequence presented sensitivity 81%, specificity 89%, and agreement between radiologists 98%, Kappa index 0.949. The axial sequence TSE-T2 is reliable for choledocholithiasis diagnosis. (Author) 9 refs.

  13. Differential scanning calorimetry.

    Science.gov (United States)

    Spink, Charles H

    2008-01-01

    Differential scanning calorimetry (DSC) has emerged as a powerful experimental technique for determining thermodynamic properties of biomacromolecules. The ability to monitor unfolding or phase transitions in proteins, polynucleotides, and lipid assemblies has not only provided data on thermodynamic stability for these important molecules, but also made it possible to examine the details of unfolding processes and to analyze the characteristics of intermediate states involved in the melting of biopolymers. The recent improvements in DSC instrumentation and software have generated new opportunities for the study of the effects of structure and changes in environment on the behavior of proteins, nucleic acids, and lipids. This review presents some of the details of application of DSC to the examination of the unfolding of biomolecules. After a brief introduction to DSC instrumentation used for the study of thermal transitions, the methods for obtaining basic thermodynamic information from the DSC curve are presented. Then, using DNA unfolding as an example, methods for the analysis of the melting transition are presented that allow deconvolution of the DSC curves to determine more subtle characteristics of the intermediate states involved in unfolding. Two types of transitions are presented for analysis, the first example being the unfolding of two large synthetic polynucleotides, which display high cooperativity in the melting process. The second example shows the application of DSC for the study of the unfolding of a simple hairpin oligonucleotide. Details of the data analysis are presented in a simple spreadsheet format.

  14. GPR scan assessment

    Directory of Open Access Journals (Sweden)

    Abbas M. Abbas

    2015-06-01

    Full Text Available Mekaad Radwan monument is situated in the neighborhood of Bab Zuweila in the historical Cairo, Egypt. It was constructed at the middle XVII century (1635 AD. The building has a rectangle shape plan (13 × 6 m with the longitudinal sides approximately WNW-ESE. It comprises three storages namely; the ground floor; the opened floor (RADWAN Bench and the living floor with a total elevation of 15 m above the street level. The building suffers from severe deterioration phenomena with patterns of damage which have occurred over time. These deterioration and damages could be attributed to foundation problems, subsoil water and also to the earthquake that affected the entire Greater Cairo area in October 1992. Ground Penetrating Radar (GPR scan was accomplished against the walls of the opened floor (RADWAN Bench to evaluate the hazard impact on the walls textures and integrity. The results showed an anomalous feature through the southern wall of RADWAN Bench. A mathematical model has been simulated to confirm the obtained anomaly and the model response exhibited a good matching with the outlined anomaly.

  15. GPR scan assessment

    Science.gov (United States)

    Abbas, Abbas M.; Salah, Hany; Massoud, Usama; Fouad, Mona; Abdel-Hafez, Mahmoud

    2015-06-01

    Mekaad Radwan monument is situated in the neighborhood of Bab Zuweila in the historical Cairo, Egypt. It was constructed at the middle XVII century (1635 AD). The building has a rectangle shape plan (13 × 6 m) with the longitudinal sides approximately WNW-ESE. It comprises three storages namely; the ground floor; the opened floor (RADWAN Bench) and the living floor with a total elevation of 15 m above the street level. The building suffers from severe deterioration phenomena with patterns of damage which have occurred over time. These deterioration and damages could be attributed to foundation problems, subsoil water and also to the earthquake that affected the entire Greater Cairo area in October 1992. Ground Penetrating Radar (GPR) scan was accomplished against the walls of the opened floor (RADWAN Bench) to evaluate the hazard impact on the walls textures and integrity. The results showed an anomalous feature through the southern wall of RADWAN Bench. A mathematical model has been simulated to confirm the obtained anomaly and the model response exhibited a good matching with the outlined anomaly.

  16. LANL Robotic Vessel Scanning

    Energy Technology Data Exchange (ETDEWEB)

    Webber, Nels W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-25

    Los Alamos National Laboratory in J-1 DARHT Operations Group uses 6ft spherical vessels to contain hazardous materials produced in a hydrodynamic experiment. These contaminated vessels must be analyzed by means of a worker entering the vessel to locate, measure, and document every penetration mark on the vessel. If the worker can be replaced by a highly automated robotic system with a high precision scanner, it will eliminate the risks to the worker and provide management with an accurate 3D model of the vessel presenting the existing damage with the flexibility to manipulate the model for better and more in-depth assessment.The project was successful in meeting the primary goal of installing an automated system which scanned a 6ft vessel with an elapsed time of 45 minutes. This robotic system reduces the total time for the original scope of work by 75 minutes and results in excellent data accumulation and transmission to the 3D model imaging program.

  17. Dynamic response of the occipito-atlanto-axial (C0-C1-C2) complex in right axial rotation.

    Science.gov (United States)

    Chang, H; Gilbertson, L G; Goel, V K; Winterbottom, J M; Clark, C R; Patwardhan, A

    1992-05-01

    The torque-angular deformation in right axial rotation until failure of the ligamentous occipito-atlanto-axial complex subjected to variable loading rate (dynamic) axial torque was characterized using a biaxial MTS system. A special fixture and gear box that permitted right axial rotation of the specimen until failure without imposing any additional constraints were used to obtain the data. The specimens were divided into three groups and tested until failure at three different dynamic loading rates: 50, 100, and 400 degrees/s. A previous study by the authors provided data for quasi-static (4 degrees/s) loading conditions. The torque versus rotation curves can be divided into two straight regions and two transition zones. The plots clearly indicated that at loading rates higher than 4 degrees/s, the specimens became stiffer in the region of steadily increasing resistance prior to failure. The increase in stiffness was maximum at 100 degrees/s. The stiffness decreased somewhat at 400 degrees/s in comparison with 100 degrees/s, but this decrease was not significant. The resulting torque-right axial rotation curves were also examined to estimate the magnitude of maximum resistance (torque) and the corresponding angular rotation value. The average maximum resistance torque increased from 13.6 Nm at 4 degrees/s to 27.8 Nm at 100 degrees/s. The corresponding right angular rotation data (65-78 degrees), however, did not show any significant variation with loading rate. Posttest dissection of the specimens indicated that the type of injury observed was related to the rate of axial loading imposed on a specimen during testing.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Three-dimensional microscopy and sectional image reconstruction using optical scanning holography.

    Science.gov (United States)

    Lam, Edmund Y; Zhang, Xin; Vo, Huy; Poon, Ting-Chung; Indebetouw, Guy

    2009-12-01

    Fast acquisition and high axial resolution are two primary requirements for three-dimensional microscopy. However, they are sometimes conflicting: imaging modalities such as confocal imaging can deliver superior resolution at the expense of sequential acquisition at different axial planes, which is a time-consuming process. Optical scanning holography (OSH) promises to deliver a good trade-off between these two goals. With just a single scan, we can capture the entire three-dimensional volume in a digital hologram; the data can then be processed to obtain the individual sections. An accurate modeling of the imaging system is key to devising an appropriate image reconstruction algorithm, especially for real data where random noise and other imaging imperfections must be taken into account. In this paper we demonstrate sectional image reconstruction by applying an inverse imaging sectioning technique to experimental OSH data of biological specimens and visualizing the sections using the OSA Interactive Science Publishing software.

  19. Quantitative analysis of disc degeneration using axial T2 mapping in a percutaneous annular puncture model in rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Jee Won; Kim, Su Jin [Dept. of Radiology, SMG-SNU Boramae Medical Center, Seoul (Korea, Republic of); Kang, Heung Sik; Lee, Joon Woo [Dept. of Radiology, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of); Hong, Sung Hwan [Dept. of Radiology, Seoul National University Hospital, Seoul (Korea, Republic of)

    2016-02-15

    To evaluate T2 relaxation time change using axial T2 mapping in a rabbit degenerated disc model and determine the most correlated variable with histologic score among T2 relaxation time, disc height index, and Pfirrmann grade. Degenerated disc model was made in 4 lumbar discs of 11 rabbits (n = 44) by percutaneous annular puncture with various severities of an injury. Lumbar spine lateral radiograph, MR T2 sagittal scan and MR axial T2 mapping were obtained at baseline and 2 weeks and 4 weeks after the injury in 7 rabbits and at baseline and 2 weeks, 4 weeks, and 6 weeks after the injury in 4 rabbits. Generalized estimating equations were used for a longitudinal analysis of changes in T2 relaxation time in degenerated disc model. T2 relaxation time, disc height index and Pfirrmann grade were correlated with the histologic scoring of disc degeneration using Spearman's rho test. There was a significant difference in T2 relaxation time between uninjured and injured discs after annular puncture. Progressive decrease in T2 relaxation time was observed in injured discs throughout the study period. Lower T2 relaxation time was observed in the more severely injured discs. T2 relaxation time showed the strongest inverse correlation with the histologic score among the variables investigated (r = -0.811, p < 0.001). T2 relaxation time measured with axial T2 mapping in degenerated discs is a potential method to assess disc degeneration.

  20. Enhanced rate performance of flexible and stretchable linear supercapacitors based on polyaniline@Au@carbon nanotube with ultrafast axial electron transport

    Science.gov (United States)

    Xu, Jiang; Ding, Jianning; Zhou, Xiaoshuang; Zhang, Yang; Zhu, Wenjun; Liu, Zunfen; Ge, Shanhai; Yuan, Ningyi; Fang, Shaoli; Baughman, Ray H.

    2017-02-01

    Linear supercapacitors suffer a severe loss of capacity at high rates due to the trade-off of radial ion diffusion and axial electron transport. Optimizing axial conductivity of electrodes is a key to circumvent this trade-off. We report here the synthesis of Au nanograin decorated aligned multiwall carbon nanotube (CNT) sheets, followed by the incorporation of polyaniline (PANI). The embedded Au nanograins results in fast radial ion diffusion and enhance axial electron transport in the linear electrodes. The flexible linear solid supercapacitor fabricated by twisting two PANI@Au@CNT yarns exhibits an outstanding electrochemical performance with a total volumetric capacitance of ∼6 F cm-3 at scan rate up to 10 V s-1. Diameter of the electrode has little effect on volumetric capacitance even at high scan rates because of its high electrical conductivity. Highly stretchable supercapacitors with high rate performance and excellent cycling and stretching stability have been also fabricated using buckled linear electrodes made by wrapping PANI@Au@CNT sheet on elastic rubber fibers. The stretchable linear supercapacitor possesses a stable total volumetric capacitance of up to ∼0.2 F cm-3 at scan rate of 1 V s-1 and at 400% strain, and remarkable capacitance retention of about 95% over 1000 stretch/release cycles.

  1. Gallium scans in myasthenia gravis

    Energy Technology Data Exchange (ETDEWEB)

    Swick, H.M. (Univ. of Kentucky, Lexington); Preston, D.F.; McQuillen, M.P.

    1976-01-01

    A study was conducted to determine whether /sup 67/Ga scans could be used for the detection of thymomas and to investigate the activity of the thymus gland in patients with myasthenia gravis. Scans of the anterior mediastinum proved to be a reliable way to detect thymomas. The scans were positive in eight patients including three with myasthenia gravis and histologically proved thymomas, three others with severe myasthenia gravis and thymic tumors, and two with histologically proved thymomas not associated with myasthenia. Activity on /sup 67/Ga scans was not directly related to the increased activity of the thymus gland that is presumed to be associated with myasthenia gravis. (HLW)

  2. On aspects of vibration of axially moving continua

    NARCIS (Netherlands)

    Hageraats-Ponomareva, S.

    2009-01-01

    In axially moving structures like conveyor belt systems, magnetic tapes, and so on, vibrations occur due to the presence of different kinds of imperfections in the systems. For these structures internal resonances can lead to severe vibrations. Resonance free conveyor belt systems can be constructed

  3. Numerical Study of Axial Turbulent Flow Over Long Cylinders

    Science.gov (United States)

    1992-04-01

    DATAV [NZ/2, MTH, 3, MR] and as DATAP[NZ/2, MTH, MR], respectively. The first index indicates the axial (streamwise) wave number I = 1, ... , NZ/2...MTH + 12, 12 !5 MTH/2, -[(THGR -1) *MTH + 12- MTH/2], I2> MTH/2. The third index in DATAV indicates the velocity component according to/3 = 3 (1 -4 V

  4. Static Tension Tests on Axially Loaded Pile Segments in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    This paper provides laboratory test results of static axially loaded piles in sand. With a newly developed test setup, the pile-soil interface friction was investigated by using an open-ended steel pile segment with a diameter of 0.5 m. Use of a pile length of 1 m enabled the pile-soil interface...

  5. Spiral thickenings in the axial Parenchyma of Chrysobalanaceae

    NARCIS (Netherlands)

    Welle, ter B.J.H.

    1976-01-01

    Spiral thickenings in the axial parenchyma, seldom recorded in the secondary xylem of the dicotyledons so far, are described for a number of genera and/or species of Chrysobalanaceae. In 66 out of 99 samples investigated, representing most genera of the Chrysobalanaceae, spiral thickenings proved to

  6. Dynamic Response of Axially Loaded Euler-Bernoulli Beams

    DEFF Research Database (Denmark)

    Bayat, M.; Barari, Amin; Shahidi, M.

    2011-01-01

    The current research deals with application of a new analytical technique called Energy Balance Method (EBM) for a nonlinear problem. Energy Balance Method is used to obtain the analytical solution for nonlinear vibration behavior of Euler-Bernoulli beams subjected to axial loads. Analytical...

  7. On the Applications of Axial Representation of Trigonometric Functions

    Science.gov (United States)

    Siadat, M. Vali

    2006-01-01

    In terms of modern pedagogy, having visual interpretation of trigonometric functions is useful and quite helpful. This paper presents, pictorially, an easy approach to prove all single angle trigonometric identities on the axes. It also discusses the application of axial representation in calculus--finding the derivative of trigonometric functions.

  8. An axially symmetric solution of metric-affine gravity

    CERN Document Server

    Vlachynsky, E J; Obukhov, Yu N; Hehl, F W

    1996-01-01

    We present an exact stationary {\\it axially symmetric} vacuum solution of metric-affine gravity (MAG) which generalises the recently reported spherically symmetric solution. Besides the metric, it carries nonmetricity and torsion as post-Riemannian geometrical structures. The parameters of the solution are interpreted as mass and angular momentum and as dilation, shear and spin charges.

  9. On the Applications of Axial Representation of Trigonometric Functions

    Science.gov (United States)

    Siadat, M. Vali

    2006-01-01

    In terms of modern pedagogy, having visual interpretation of trigonometric functions is useful and quite helpful. This paper presents, pictorially, an easy approach to prove all single angle trigonometric identities on the axes. It also discusses the application of axial representation in calculus--finding the derivative of trigonometric functions.

  10. Treatment with tumor necrosis factor inhibitors in axial spondyloarthritis

    DEFF Research Database (Denmark)

    Ciurea, A.; Weber, U.; Stekhoven, D.

    2015-01-01

    Objective. To evaluate the initiation of and response to tumor necrosis factor (TNF) inhibitors for axial spondyloarthritis (axSpA) in private rheumatology practices versus academic centers. The Journal of Rheumatology, Methods.We compared newly initiated TNF inhibition for axSpA in 363 patients...

  11. On aspects of vibration of axially moving continua

    NARCIS (Netherlands)

    Hageraats-Ponomareva, S.

    2009-01-01

    In axially moving structures like conveyor belt systems, magnetic tapes, and so on, vibrations occur due to the presence of different kinds of imperfections in the systems. For these structures internal resonances can lead to severe vibrations. Resonance free conveyor belt systems can be constructed

  12. On the generation techniques of axially symmetric stationary metrics

    Indian Academy of Sciences (India)

    S Chaudhuri

    2002-03-01

    In the present paper, a relationship between the method of Gutsunaev–Manko and the soliton technique (for two-soliton solutions) of Belinskii–Zakharov, for generating solutions of axially symmetric stationary space-times in general relativity is discussed.

  13. Limb-length discrepancy measured with computerized axial tomographic equipment

    Energy Technology Data Exchange (ETDEWEB)

    Huurman, W.W.; Jacobsen, F.S.; Anderson, J.C.; Chu, W.K.

    1987-06-01

    A simple, rapid, and accurate method for measuring limb-length discrepancies with computerized axial tomographic equipment is described. With this method less irradiation is delivered and some of the errors of computation are eliminated, compared with conventional methods. The costs of the technique are comparable with those of scanograms. The method is particularly applicable in the patient who has contracture of a joint.

  14. Observers in spacetimes with spherical and axial symmetries

    OpenAIRE

    Gusin, Pawel; Kusnierz, Bartosz; Radosz, Andrzej

    2015-01-01

    We introduce in the explicit form the tetrads of arbitrary observers in spacetimes with spherical and axial symmetries. The observers confined to the equatorial plane are parametrized by the pair of functions. We apply this description in the analysis of the null-geodesics in the observers' frames. The observers with the constant acceleration are distinguished.

  15. FINITE ELEMENT ANALYSIS OF AXIAL FEED BAR ROLLING

    Institute of Scientific and Technical Information of China (English)

    C.G. Xu; G.H. Liu; G.S. Ren; Z. Shen; C.P. Ma; W. W. Ren

    2007-01-01

    A flexible technique of hot working of bars by axial feed rolling was introduced. The processdeformation, strain field, stress field, and temperature field of the parts are analyzed by finite elementmethod (FEM)-simulation software DEFORM-3D. The material flow rule and tool load have beeninvestigated.

  16. Axially Symmetric Cosmological Mesonic Stiff Fluid Models in Lyra's Geometry

    CERN Document Server

    Gad, Ragab M

    2009-01-01

    In this paper, we obtained a new class of axially symmetric cosmological mesonic stiff fluid models in the context of Lyra's geometry. Expressions for the energy, pressure and the massless scalar field are derived by considering the time dependent displacement field. We found that the mesonic scalar field depends on only $t$ coordinate. Some physical properties of the obtained models are discussed.

  17. Axially symmetric solutions in f(R)-gravity

    CERN Document Server

    Capozziello, Salvatore; Stabile, Arturo

    2009-01-01

    Axially symmetric solutions for f(R)-gravity can be derived starting from exact spherically symmetric solutions. The method takes advantage of a complex coordinate transformation previously developed by Newman and Janis in General Relativity. An example is worked out to show the general validity of the approach.

  18. Axially symmetric solutions in f(R)-gravity

    Energy Technology Data Exchange (ETDEWEB)

    Capozziello, Salvatore; De Laurentis, Mariafelicia [Dipartimento di Scienze Fisiche, Universita di Napoli ' Federico II' (Italy); Stabile, Arturo, E-mail: capozziello@na.infn.i [Dipartimento di Ingegneria, Universita del Sannio, Benevento, C.so Garibaldi 107, I-80125 Benevento (Italy)

    2010-08-21

    Axially symmetric solutions for f(R)-gravity can be derived starting from exact spherically symmetric solutions achieved by Noether symmetries. The method takes advantage of a complex coordinate transformation previously developed by Newman and Janis in general relativity. An example is worked out to show the general validity of the approach. The physical properties of the solution are also considered.

  19. Hydrostatic self-aligning axial/torsional mechanism

    Science.gov (United States)

    O'Connor, Daniel G.; Gerth, Howard L.

    1990-01-01

    The present invention is directed to a self-aligning axial/torsional loading mechanism for testing the strength of brittle materials which are sensitive to bending moments. Disposed inside said self-aligning loading mechanism is a frictionless hydrostatic ball joint with a flexure ring to accommodate torsional loads through said ball joint.

  20. Multi-axial mechanical stimulation of tissue engineered cartilage: Review

    Directory of Open Access Journals (Sweden)

    S D Waldman

    2007-04-01

    Full Text Available The development of tissue engineered cartilage is a promising new approach for the repair of damaged or diseased tissue. Since it has proven difficult to generate cartilaginous tissue with properties similar to that of native articular cartilage, several studies have used mechanical stimuli as a means to improve the quantity and quality of the developed tissue. In this study, we have investigated the effect of multi-axial loading applied during in vitro tissue formation to better reflect the physiological forces that chondrocytes are subjected to in vivo. Dynamic combined compression-shear stimulation (5% compression and 5% shear strain amplitudes increased both collagen and proteoglycan synthesis (76 ± 8% and 73 ± 5%, respectively over the static (unstimulated controls. When this multi-axial loading condition was applied to the chondrocyte cultures over a four week period, there were significant improvements in both extracellular matrix (ECM accumulation and the mechanical properties of the in vitro-formed tissue (3-fold increase in compressive modulus and 1.75-fold increase in shear modulus. Stimulated tissues were also significantly thinner than the static controls (19% reduction suggesting that there was a degree of ECM consolidation as a result of long-term multi-axial loading. This study demonstrated that stimulation by multi-axial forces can improve the quality of the in vitro-formed tissue, but additional studies are required to further optimize the conditions to favour improved biochemical and mechanical properties of the developed tissue.

  1. Axially and spherically symmetric solitons in warm plasma

    CERN Document Server

    Dvornikov, Maxim

    2010-01-01

    We study the existence of stable axially and spherically symmetric plasma structures on the basis of the new nonlinear Schrodinger equation (NLSE) accounting for nonlocal electron nonlinearities. The numerical solutions of NLSE having the form of spatial solitions are obtained and their stability is analyzed. We discuss the possible application of the obtained results to the theoretical description of natural plasmoids in the atmosphere.

  2. Chondrocyte activity is increased in psoriatic arthritis and axial spondyloarthritis

    DEFF Research Database (Denmark)

    Gudmann, Natasja Stæhr; Munk, Heidi Lausten; Christensen, Anne Friesgaard

    2016-01-01

    BACKGROUND: Psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA) are chronic inflammatory rheumatic diseases with complex origins. Both are characterized by altered extracellular matrix remodeling in joints and entheses that results in destructive and osteochondral proliferative lesions...

  3. Etanercept for the treatment of non-radiographic axial spondyloarthritis.

    Science.gov (United States)

    Rios Rodriguez, Valeria; Poddubnyy, Denis

    2016-01-01

    Presently, tumor necrosis factor α antagonist therapy is the only effective alternative treatment to nonsteroidal anti-inflammatory drugs for the entire spectrum of axial spondyloarthritis, including non-radiographic and radiographic (=ankylosing spondylitis) forms. Recently, etanercept has been approved by the European Medicines Agency for the treatment of non-radiographic axial spondyloarthritis, increasing the number of available treatment options for this indication. The latest data on etanercept concerning clinical efficacy and safety in short-term and long-term treatment of patients with non-radiographic axial spondyloarthritis who do not respond to the first-line therapy with non-steroidal anti-inflammatory drugs suggests good efficacy and safety profiles similar to that observed previously in ankylosing spondylitis. This article reviews recent data on the efficacy and safety of etanercept and is focused on the treatment of non-radiographic axial spondyloarthritis. This article will also discuss the role of etanercept in the context of current and developing treatment options.

  4. A cylindrical drift chamber with azimuthal and axial position readout

    Energy Technology Data Exchange (ETDEWEB)

    Bar-Yam, Z.; Cummings, J.P.; Dowd, J.P.; Eugenio, P.; Hayek, M.; Kern, W.; King, E.; Shenhav, N.; Chung, S.U.; Hackenburg, R.W.; Olchanski, C.; Weygand, D.P.; Willutzki, H.J.; Brabson, B.B.; Crittenden, R.R.; Dzierba, A.R.; Gunter, J.; Lindenbusch, R.; Rust, D.R.; Scott, E.; Smith, P.T.; Sulanke, T.; Teige, S.; Denisov, S.; Dushkin, A.; Kochetkov, V.; Lipaev, V.; Popov, A.; Shein, I.; Soldatov, A.; Anoshina, E.V.; Bodyagin, V.A.; Demianov, A.I.; Gribushin, A.M.; Kodolova, O.L.; Korotkikh, V.L.; Kostin, M.A.; Ostrovidov, A.I.; Sarycheva, L.I.; Sinev, N.B.; Vardanyan, I.N.; Yershov, A.A.; Adams, T.; Bishop, J.M.; Cason, N.M.; Sanjari, A.H.; LoSecco, J.M.; Manak, J.J.; Shephard, W.D.; Stienike, D.L.; Taegar, S.A.; Thompson, D.R.; Brown, D.S.; Pedlar, T.; Seth, K.K.; Wise, J.; Zhao, D.; Adams, G.S.; Napolitano, J.; Nozar, M.; Smith, J.A.; Witkowski, M. [Massachusetts Univ., North Dartmouth, MA (United States)]|[Brookhaven National Laboratory, Upton, L.I., NY 11973 (United States)]|[Indiana University, Bloomington, IN 47405 (United States)]|[Institute for High Energy Physics, Protvino (Russian Federation)]|[Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation)]|[University of Notre Dame, Notre Dame, IN 46556 (United States)]|[Northwestern University, Evanston, IL 60208 (United States)]|[Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    1997-02-21

    A cylindrical multiwire drift chamber with axial charge-division has been constructed and used in experiment E852 at Brookhaven National Laboratory. It serves as a trigger element and as a tracking device for recoil protons in {pi}{sup -}p interactions. We describe the chamber`s design considerations, details of its construction, electronics, and performance characteristics. (orig.).

  5. 3-D Simulation of Vertical-Axial Tidal Current Turbine

    Directory of Open Access Journals (Sweden)

    Zhiyang Zhang

    2016-12-01

    Full Text Available Vertical-axial tidal current turbine is the key for the energy converter, which has the advantages of simple structure, adaptability to flow and uncomplex convection device. It has become the hot point for research and application recently. At present, the study on the hydrodynamic performance of vertical-axial tidal current turbine is almost on 2-D numerical simulation, without the consideration of 3-D effect. CFD (Computational Fluid Dynamics method and blade optimal control technique are used to improve accuracy in the prediction of tidal current turbine hydrodynamic performance. Numerical simulation of vertical-axial tidal current turbine is validated. Fixed and variable deflection angle turbine are comparatively studied to analysis the influence of 3-D effect and the character of fluid field and pressure field. The method, put the plate on the end of blade, of reduce the energy loss caused by 3-D effect is proposed. The 3-D CFD numerical model of vertical-axial tidal current turbine hydrodynamic performance in this study may provide theoretical, methodical and technical reference for the optimal design of turbine.

  6. Optimal design of multi-conditions for axial flow pump

    Science.gov (United States)

    Shi, L. J.; Tang, F. P.; Liu, C.; Xie, R. S.; Zhang, W. P.

    2016-11-01

    Passage components of the pump device will have a negative flow state when axial pump run off the design condition. Combined with model tests of axial flow pump, this paper use numerical simulation and numerical optimization techniques, and change geometric design parameters of the impeller to optimal design of multi conditions for Axial Flow Pump, in order to improve the efficiency of non-design conditions, broad the high efficient district and reduce operating cost. The results show that, efficiency curve of optimized significantly wider than the initial one without optimization. The efficiency of low flow working point increased by about 2.6%, the designed working point increased by about 0.5%, and the high flow working point increased the most, about 7.4%. The change range of head is small, so all working point can meet the operational requirements. That will greatly reduce operating costs and shorten the period of optimal design. This paper adopted the CFD simulation as the subject analysis, combined with experiment study, instead of artificial way of optimization design with experience, which proves the reliability and efficiency of the optimization design of multi-operation conditions of axial-flow pump device.

  7. Further comment on pion electroproduction and the axial form factor

    CERN Document Server

    Bernard, V; Meißner, Ulf G; Mei{\\ss}ner, Ulf-G.

    2001-01-01

    We show that a recent claim (H.Haberzettl, Phys. Rev. Lett. 85 (2000) 3576) that one cannot extract the nucleon weak axial form factor G_A (t) from charged pion threshold electroproduction is incorrect. Thus previous calculations remain valid and threshold charged pion electroproduction experiments can indeed be used to determine G_A (t), and they should certainly be pursued.

  8. The cause of axial rotation of the scoliotic spine

    NARCIS (Netherlands)

    Lemmers, L.G.; Sanders, M.M.; Cool, J.C.; Grootenboer, H.J.

    1991-01-01

    To explain the cause of axial rotation in a scoliotic vertebral column, the influence of the gravitation force on a spine with a C-scoliosis has been investigated by means of a mechanical model. In this model the gravitation force takes hold of the three-dimensionally curved vertebral column eccentr

  9. Dynamic Behaviors of Axially Moving Viscoelastic Plate with Varying Thicknessn

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yinfeng; WANG Zhongmin

    2009-01-01

    Structural components of varying thickness draw increasing attention these days due to economy and light-weight considerations. In view of the absence of research in vibration analysis of viscoelastic plate with varying thickness, this study devotes to investigate the dynamic behaviors of axially moving viscoelastic plate with varying thickness. Based on the thin plate theory and the two-dimensional viscoelastic differential constitutive relation, the differential equation of motion of the axially moving viscoelastic rectangular plate is derived, the plate constituted by Kelvin-Voigt model has linearly varying thickness in the y-direction. The dimensionless complex frequencies of axially moving viscoelastic plate with four edges simply supported are calculated by the differential quadrature method, curves of real parts and imaginary parts of the first three-order dimensionless complex frequencies versus dimensionless moving speed are obtained, the effects of the aspect ratio, thickness ratio, the dimensionless moving speed and delay time on the dynamic behaviors of the axially moving viscoelastic rectangular plate with varying thickness are analyzed. When other parameters keep constant, with the decrease of thickness ratio, the real parts of the first three-order natural frequencies decrease, and the critical divergence speeds of various modes decrease too, moreover, whether the delay time is large or small, the frequencies are all complex numbers.

  10. Finite Difference Solution for Biopotentials of Axially Symmetric Cells

    Science.gov (United States)

    Klee, Maurice; Plonsey, Robert

    1972-01-01

    The finite difference equations necessary for calculating the three-dimensional, time-varying biopotentials within and surrounding axially symmetric cells are presented. The method of sucessive overrelaxation is employed to solve these equations and is shown to be rapidly convergent and accurate for the exemplary problem of a spheroidal cell under uniform field stimulation. PMID:4655665

  11. View of the Axial Field Spectrometer (R807)

    CERN Multimedia

    1980-01-01

    In this view of the Axial Field Spectrometer at I8, the vertical uranium/scintillator hadron calorimeter (just left of centre) is retracted to give access to the cylindrical central drift chamber. The yellow iron structure served as a filter to identify muons, with MWPCs and the array of Cherenkov counters to the right.

  12. Axial dispersion in flowing red blood cell suspensions

    Science.gov (United States)

    Podgorski, Thomas; Losserand, Sylvain; Coupier, Gwennou

    2016-11-01

    A key parameter in blood microcirculation is the transit time of red blood cells (RBCs) through an organ, which can influence the efficiency of gas exchange and oxygen availability. A large dispersion of this transit time is observed in vivo and is partly due to the axial dispersion in the flowing suspension. In the classic Taylor-Aris example of a solute flowing in a tube, the combination of molecular diffusion and parabolic velocity profile leads to enhanced axial dispersion. In suspensions of non-Brownian deformable bodies such as RBCs, axial dispersion is governed by a combination of shear induced migration and shear-induced diffusion arising from hydrodynamic interactions. We revisit this problem in the case of RBC pulses flowing in a microchannel and show that the axial dispersion of the pulse eventually saturates with a final extension that depends directly on RBC mechanical properties. The result is especially interesting in the dilute limit since the final pulse length depends only on the channel width, exponent of the migration law and dimensionless migration velocity. In continuous flow, the dispersion of transit times is the result of complex cell-cell and cell-wall interactions and is strongy influenced by the polydispersity of the blood sample. The authors acknowledge support from LabEx TEC21 and CNES.

  13. Periodicity effects of axial waves in elastic compound rods

    DEFF Research Database (Denmark)

    Nielsen, R. B.; Sorokin, S. V.

    2015-01-01

    Floquet analysis is applied to the Bernoulli-Euler model for axial waves in a periodic rod. Explicit asymptotic formulae for the stop band borders are given and the topology of the stop band pattern is explained. Eigenfrequencies of the symmetric unit cell are determined by the Phase-closure Prin...

  14. Atlantoaxial Ankylosis Detected on Neck CT Scans in a Patient with Ankylosing Spondylitis: A Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Ah; Lee, Seung Hun; Joo, Kyung Bin [Dept. of Radiology, Seoul Hospital, Hanyang University College of Medicine, Seoul (Korea, Republic of); Ryu, Jeong Ah [Dept. of Radiology, Guri Hospital, Hanyang University College of Medicine, Guri (Korea, Republic of); Kim, Tae Hwan [Dept. of Rheynmatology, Seoul Hospital, Hanyang University College of Medicine, Seoul (Korea, Republic of)

    2011-07-15

    Ankylosing spondylitis is a chronic inflammatory disorder of unknown cause that principally affects the axial skeleton. The cervical spine is also vulnerable to this disease process and the characteristic feature of cervical involvement is atlantoaxial subluxation. However, only a few cases of atlantoaxial ankylosis have been reported to date. We report a case of atlantoaxial ankylosis in a patient with ankylosing spondylitis with radiologic findings incidentally detected on neck CT scans.

  15. Re-scan confocal microscopy: scanning twice for better resolution

    NARCIS (Netherlands)

    De Luca, G.M.R.; Breedijk, R.M.P.; Brandt, R.A.J.; Zeelenberg, C.H.C.; De Jong, B.E.; Timmermans, W.; Nahidi Azar, L.; Hoebe, R.A.; Stallinga, S.; Manders, E.M.M.

    2013-01-01

    We present a new super-resolution technique, Re-scan Confocal Microscopy (RCM), based on standard confocal microscopy extended with an optical (re-scanning) unit that projects the image directly on a CCD-camera. This new microscope has improved lateral resolution and strongly improved sensitivity wh

  16. Re-scan confocal microscopy : scanning twice for better resolution

    NARCIS (Netherlands)

    De Luca, G.M.R.; Breedijk, R.M.P.; Brandt, R.A.J.; Zeelenberg, C.H.C.; de Jong, B.E.; Timmermans, W.; Azar, L.N.; Hoebe, R.A.; Stallinga, S.; Manders, E.M.M.

    2013-01-01

    We present a new super-resolution technique, Re-scan Confocal Microscopy (RCM), based on standard confocal microscopy extended with an optical (re-scanning) unit that projects the image directly on a CCD-camera. This new microscope has improved lateral resolution and strongly improved sensitivity wh

  17. Uni-axial compaction of a granular material

    Science.gov (United States)

    Morland, L. W.; Sawicki, A.; Milne, P. C.

    1993-11-01

    S HEARING OF GRANULAR materials causes rearrangement of the granular structure which induces irreversible volume decrease and shear strain, in addition to reversible strain. The model adopted describes the reversible compression and shear by hypoelastic laws, and the irreversible compaction and shear by evolutionary laws. The latter are differential relations defining the progress of irreversible strain as an appropriate time-independent monotonie loading parameter increases, which incorporate dependence on the current state, and which prescribe a direction for the irreversible shear strain increment. The model is described by four material functions and two material constants, and has been shown to determine valid initial response to applied shear stress. We apply the model to the compaction of a granular material in uni-axial strain, which is described by two simultaneous differential equations for the axial stress and compaction with the axial strain as independent variable, together with algebraic relations for the pressure and lateral stress. The equation forms for loading-increasing axial stress—and unloading—decreasing axial stress-are distinct. Reformulation as differential equations for the pressure and the principal stress difference shows that the pressure derivative depends only on two of the material functions and one constant. The axial strain and lateral stress measured during a complete load-unload cycle on a sand determine the pressure and stress difference derivatives which are correlated directly with the model differential relations. Two material functions and one constant are determined by an optimization procedure from the complete loadunload ressure data, then the remaining two functions and constant from the stress difference data. Solution of the resulting model differential equations reproduces accurately the axial strain and lateral stress variations during the experimental loading cycle. In addition, model predictions for load

  18. Finite element simulation of laser tube bending: Effect of scanning schemes on bending angle, distortions and stress distribution

    Science.gov (United States)

    Safdar, Shakeel; Li, Lin; Sheikh, M. A.; Zhu Liu

    2007-09-01

    Laser forming has received considerable attention in recent years. Within laser forming, tube bending is an important industrial activity, with applications in critical engineering systems like micro-machines, heat exchangers, hydraulic systems, boilers, etc. Laser tube bending utilizes the thermal stresses generated during laser scanning to achieve the desired bends. The parameters to control the process are usually laser power, beam diameter, scanning velocity and number of scans. Recently axial scanning has been used for tube bending instead of commonly used circumferential scans. However the comparison between the scanning schemes has involved dissimilar laser beam geometries with circular beam used for circumferential scanning and a rectangular beam for the axial scan. Thermal stresses generated during laser scanning are strongly dependent upon laser beam geometry and scanning direction and hence it is difficult to isolate the contribution made by these two variables. It has recently been established at the Corrosion and Protection Centre, University of Manchester, that corrosion properties of material during laser forming are affected by the number of laser passes. Depending on the material, the corrosion behaviour is either adversely or favourably affected by number of passes. Thus it is of great importance to know how different scanning schemes would affect laser tube bending. Moreover, any scanning scheme which results in greater bending angle would eliminate the need for higher number of passes, making the process faster. However, it is not only the bending angle which is critical, distortions in other planes are also extremely important. Depending on the use of the final product, unwanted distortions may be the final selection criteria. This paper investigates the effect of scanning direction on laser tube bending. Finite-element modelling has been used for the study of the process with some results also validated by experiments.

  19. Scanning tunneling microscopy II further applications and related scanning techniques

    CERN Document Server

    Güntherodt, Hans-Joachim

    1992-01-01

    Scanning Tunneling Microscopy II, like its predecessor, presents detailed and comprehensive accounts of the basic principles and broad range of applications of STM and related scanning probe techniques. The applications discussed in this volume come predominantly from the fields of electrochemistry and biology. In contrast to those described in Vol. I, these sudies may be performed in air and in liquids. The extensions of the basic technique to map other interactions are described inchapters on scanning force microscopy, magnetic force microscopy, scanning near-field optical microscopy, together with a survey of other related techniques. Also described here is the use of a scanning proximal probe for surface modification. Togehter, the two volumes give a comprehensive account of experimental aspcets of STM. They provide essentialreading and reference material for all students and researchers involvedin this field.

  20. Scanning tunneling microscopy II further applications and related scanning techniques

    CERN Document Server

    Güntherodt, Hans-Joachim

    1995-01-01

    Scanning Tunneling Microscopy II, like its predecessor, presents detailed and comprehensive accounts of the basic principles and broad range of applications of STM and related scanning probe techniques. The applications discussed in this volume come predominantly from the fields of electrochemistry and biology. In contrast to those described in STM I, these studies may be performed in air and in liquids. The extensions of the basic technique to map other interactions are described in chapters on scanning force microscopy, magnetic force microscopy, and scanning near-field optical microscopy, together with a survey of other related techniques. Also described here is the use of a scanning proximal probe for surface modification. Together, the two volumes give a comprehensive account of experimental aspects of STM. They provide essential reading and reference material for all students and researchers involved in this field. In this second edition the text has been updated and new methods are discussed.