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Sample records for artery wall thickness

  1. Ultrasound settings significantly alter arterial lumen and wall thickness measurements

    OpenAIRE

    Green Daniel J; Reed Christopher J; Potter Kathleen; Hankey Graeme J; Arnolda Leonard F

    2008-01-01

    Abstract Background Flow-mediated dilation (FMD) and carotid intima-medial thickness (CIMT), measured by ultrasound, are widely used to test the efficacy of cardioprotective interventions. Although assessment methods vary, automated edge-detecting image analysis software is routinely used to measure changes in FMD and CIMT. We aimed to quantify the effect that commonly adjusted ultrasound settings have on arterial lumen and wall thickness measurements made with CIMT measurement software. Meth...

  2. Ultrasound settings significantly alter arterial lumen and wall thickness measurements

    Directory of Open Access Journals (Sweden)

    Green Daniel J

    2008-01-01

    Full Text Available Abstract Background Flow-mediated dilation (FMD and carotid intima-medial thickness (CIMT, measured by ultrasound, are widely used to test the efficacy of cardioprotective interventions. Although assessment methods vary, automated edge-detecting image analysis software is routinely used to measure changes in FMD and CIMT. We aimed to quantify the effect that commonly adjusted ultrasound settings have on arterial lumen and wall thickness measurements made with CIMT measurement software. Methods We constructed phantom arteries from a tissue-mimicking agar compound and scanned them in a water bath with a 10 MHz multi-frequency linear-array probe attached to a high-resolution ultrasound machine. B-mode images of the phantoms were recorded with dynamic range (DR and gain set at five decibel (dB increments from 40 dB to 60 dB and -10 dB to +10 dB respectively. Lumen diameter and wall-thickness were measured off-line using CIMT measurement software. Results Lumen measurements: there was a strong linear relationship between DR and gain and measured lumen diameter. For a given gain level, a 5 dB increase in DR reduced the measured lumen diameter by 0.02 ± 0.004 mm (p CIMT measurements: For a fixed gain level, a 5 dB increase in DR increased measured wall thickness by 0.003 ± 0.002 mm (p Conclusion DR, gain and probe distance significantly alter lumen diameter and CIMT measurements made using image analysis software. When CIMT and FMD are used to test the efficacy of cardioprotective interventions, the DR, gain and probe position used to record baseline scans should be documented and replicated in post-treatment scans in individual trial subjects. If more than one sonographer or imaging centre is used to collect data, the study protocol should document specific DR and gain settings to be used in all subjects.

  3. Optimization of Condition of Ultrasonic Beam for Measurement of Small Change in Thickness of Arterial Wall

    Science.gov (United States)

    Watanabe, Masaru; Hasegawa, Hideyuki; Kanai, Hiroshi

    2002-05-01

    We previously developed a method for measuring small changes in thickness of the arterial wall during one cardiac cycle. Knowledge of this change in thickness is useful for in vivo assessment of the regional elasticity of the arterial wall. In this study, from computer simulations, it is found that measurement error depends on the distance of the ultrasonic beam from the center of the artery and it can be reduced by optimally setting the focal position. In basic experiments using a silicone rubber tube and in in vivo experiments with a human carotid artery, it is found that by optimizing the focal position, measurement of the change in thickness becomes more robust against mispositioning of the ultrasonic beam. From these results, it is demonstrated that optimum focal positioning provides more robustness in measurement, even if there is arterial wall motion causing the position of the ultrasonic beam to deviate from the center of the artery.

  4. Optimization of Focal Position of Ultrasonic Beam in Measurement of Small Change in Arterial Wall Thickness

    Science.gov (United States)

    Watanabe, Masaru; Kanai, Hiroshi

    2001-05-01

    We have previously developed a method for measurement of a small change in thickness of the arterial wall during a single cardiac cycle [H. Kanai, M. Sato, Y. Koiwa and N. Chubachi: IEEE Trans. UFFC 43 (1996) 791]. The resultant change in thickness is shown to be useful for the in vivo assessment of the regional elasticity of the arterial wall. Although the accuracy of the measurement of the change in thickness is found to be within 1 μm, it is affected by the interference of ultrasonic pulses. In this study, we simulate the propagation of ultrasonic pulses transmitted and received by a linear probe. In the simulation experiments, the ultrasonic pulses generated by a computer are reflected by a tube, which has a small change in wall thickness of 10 μm. The optimum focal position of the ultrasonic beam is determined by evaluating the root-mean-square (rms) error in the measured change in thickness.

  5. Coronary Artery Calcium, Carotid Artery Wall Thickness and Cardiovascular Disease Outcomes in Adults 70 to 99 Years Old

    OpenAIRE

    Newman, Anne B; Naydeck, Barbara L.; Ives, Diane G.; Boudreau, Robert M.; Sutton-Tyrrell, Kim; O Leary, Daniel H.; Kuller, Lewis H.

    2008-01-01

    Few population studies have evaluated the associations of both coronary artery calcium (CAC) and carotid ultrasound with cardiovascular events, especially in adults > 70 years of age. At the Pittsburgh Field Center of the Cardiovascular Health Study, 559 men and women, mean age 80.2 (SD 4.1) years had CAC score assessed by electron beam computerized tomography scan and common and internal carotid intimal-medial wall thickness (CCA-IMT and ICA-IMT) by carotid ultrasound between 1998−2000 and w...

  6. Positive association between increased popliteal artery vessel wall thickness and generalized osteoarthritis: is OA also part of the metabolic syndrome?

    International Nuclear Information System (INIS)

    The purpose of the study was to determine if a positive association exists between arterial vessel wall thickness and generalized osteoarthritis (OA). Our hypothesis is that generalized OA is another facet of the metabolic syndrome. The medical ethical review board of our institution approved the study. Written informed consent was obtained from each patient prior to the study. Magnetic resonance (MR) images of the knee were obtained in 42 patients who had been diagnosed with generalized OA at multiple joint sites. Another 27 MR images of the knee were obtained from a matched normal (non-OA) reference population. Vessel wall thickness of the popliteal artery was quantitatively measured by dedicated software. Linear regression models were used to investigate the association between vessel wall thickness and generalized OA. Adjustments were made for age, sex, and body mass index (BMI). Confidence intervals (CI) were computed at the 95% level and a significance level of α = 0.05 was used. Patients in the generalized OA population had a significant higher average vessel wall thickness than persons from the normal reference population (p ≤ α), even when correction was made for sex, age, and BMI. The average vessel wall thickness of the popliteal artery was 1.09 mm in patients with generalized OA, and 0.96 mm in the matched normal reference population. The association found between increased popliteal artery vessel wall thickness and generalized osteoarthritis suggests that generalized OA might be another facet of the metabolic syndrome. (orig.)

  7. Comparison between Carotid Artery Wall Thickness Measured by Multidetector Row Computed Tomography Angiography and Intimae-Media Thickness Measured by Sonography

    OpenAIRE

    Živorad N. Savić; Ivan I. Soldatović; Milan D. Brajović; Aleksandra M. Pavlović; Dušan R. Mladenović; Vesna D. Škodrić-Trifunović

    2011-01-01

    The increased thickness of the carotid wall >1 mm is a significant predictor of coronary and cerebrovascular diseases. The purpose of our study was to assess the agreement between multidetector row computed tomography angiography (MDCTA) in measuring carotid artery wall thickness (CAWT) and color Doppler ultrasound (CD-US) in measuring intimae-media thickness (IMT). Eighty-nine patients (aged 35–81) were prospectively analyzed using a 64-detector MDCTA and a CD-US scanner. Continuous data wer...

  8. Time course of arterial remodelling in diameter and wall thickness above and below the lesion after a spinal cord injury

    OpenAIRE

    Dick H J Thijssen; de Groot, Patricia C. E.; van den Bogerd, Arne; Veltmeijer, Matthijs; Cable, N. Timothy; Green, Daniel J.; Hopman, Maria T. E.

    2012-01-01

    Physical inactivity in response to a spinal cord injury (SCI) represents a potent stimulus for conduit artery remodelling. Changes in conduit artery characteristics may be induced by the local effects of denervation (and consequent extreme inactivity below the level of the lesion), and also by systemic adaptations due to whole body inactivity. Therefore, we assessed the time course of carotid (i.e. above lesion) and common femoral artery (i.e. below lesion) lumen diameter and wall thickness a...

  9. Carotid artery wall thickness: comparison between sonography and multi-detector row CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Saba, Luca [University of Cagliari, Department of Radiology, Policlinico Universitario, Cagliari (Italy); Sanfilippo, Roberto; Montisci, Roberto [Policlinico Universitario, Department of Vascular Surgery, Cagliari (Italy); Mallarini, Giorgio [University of Cagliari, Department of Radiology, Policlinico Universitario, Cagliari (Italy); Ospedale San Giovanni di Dio, Institute of Radiology, Cagliari (Italy)

    2010-02-15

    Prospective studies have shown that an increased thickness of the carotid wall is a significant predictor of coronary and cerebrovascular complications. Our purpose was to assess the agreement between multi-detector row computed tomography (CT) angiography (MDCTA) and colour Doppler ultrasound (CD-US) in measuring carotid artery wall thickness (CAWT) and the intima-media thickness (IMT). Altogether, 97 subjects (age range 64-84 years) were prospectively analysed using a four-detector row CT and a sonographic scanner. In total, 46 subjects had shown cerebral ischaemic symptoms. CAWT and IMT were measured in each patient using MDCTA and CD-US (by applying a digital calliper), respectively. Continuous data were described as the mean value {+-} standard deviation and were compared using the Mann-Whitney U test. A p value <0.05 was considered significant. Bland-Altman statistics was employed to measure the agreement between MDCTA and CD-US. CAWT ranged from 0.5 to 1.53 mm, with a mean value of 0.9072 mm. IMT ranged from 0.46 to 1.5 mm, with a mean value of 0.8839 mm. By analysing the Bland-Altman plot, we observed an excellent agreement between CD-US and MDCTA with a bias between methods of 0.023 {+-} 0.0424 mm. A limit of agreement from -0.06 to 0.106 was recorded. Correlation coefficient r was 0.9855 (95% confidence interval 0.9808-0.989). Mann-Whitney U test indicated a p value of 0.377. Obtained results indicated a significant agreement between MDCTA and CD-US in the measurement of CAWT and IMT. (orig.)

  10. Carotid artery wall thickness: comparison between sonography and multi-detector row CT angiography

    International Nuclear Information System (INIS)

    Prospective studies have shown that an increased thickness of the carotid wall is a significant predictor of coronary and cerebrovascular complications. Our purpose was to assess the agreement between multi-detector row computed tomography (CT) angiography (MDCTA) and colour Doppler ultrasound (CD-US) in measuring carotid artery wall thickness (CAWT) and the intima-media thickness (IMT). Altogether, 97 subjects (age range 64-84 years) were prospectively analysed using a four-detector row CT and a sonographic scanner. In total, 46 subjects had shown cerebral ischaemic symptoms. CAWT and IMT were measured in each patient using MDCTA and CD-US (by applying a digital calliper), respectively. Continuous data were described as the mean value ± standard deviation and were compared using the Mann-Whitney U test. A p value <0.05 was considered significant. Bland-Altman statistics was employed to measure the agreement between MDCTA and CD-US. CAWT ranged from 0.5 to 1.53 mm, with a mean value of 0.9072 mm. IMT ranged from 0.46 to 1.5 mm, with a mean value of 0.8839 mm. By analysing the Bland-Altman plot, we observed an excellent agreement between CD-US and MDCTA with a bias between methods of 0.023 ± 0.0424 mm. A limit of agreement from -0.06 to 0.106 was recorded. Correlation coefficient r was 0.9855 (95% confidence interval 0.9808-0.989). Mann-Whitney U test indicated a p value of 0.377. Obtained results indicated a significant agreement between MDCTA and CD-US in the measurement of CAWT and IMT. (orig.)

  11. Assessment of normal and atherosclerotic arterial wall thickness with an intravascular ultrasound imaging catheter.

    OpenAIRE

    Mallery, JA; Tobis, JM; Griffith, J.; Gessert, J; McRae, M; Moussabeck, O; Bessen, M; Moriuchi, M; Henry, WL

    1990-01-01

    A prototype intravascular ultrasound imaging catheter with a 20 MHz transducer was used to obtain 59 cross-sectional images in 14 segments of human atherosclerotic arteries. Three distinct components of the arterial wall were visualized on the ultrasound images: a highly reflective intima, an echolucent media, and a moderately reflective adventitia. Images were obtained at 1 mm increments in vitro and were compared with histologic sections at the same levels. Measurements of the arterial laye...

  12. Cross-Sectional Elasticity Imaging of Arterial Wall by Comparing Measured Change in Thickness with Model Waveform

    Science.gov (United States)

    Tang, Jiang; Hasegawa, Hideyuki; Kanai, Hiroshi

    2005-06-01

    For the assessment of the elasticity of the arterial wall, we have developed the phased tracking method [H. Kanai et al.: IEEE Trans. Ultrason. Ferroelectr. Freq. Control 43 (1996) 791] for measuring the minute change in thickness due to heartbeats and the elasticity of the arterial wall with transcutaneous ultrasound. For various reasons, for example, an extremely small deformation of the wall, the minute change in wall thickness during one heartbeat is largely influenced by noise in these cases and the reliability of the elasticity distribution obtained from the maximum change in thickness deteriorates because the maximum value estimation is largely influenced by noise. To obtain a more reliable cross-sectional image of the elasticity of the arterial wall, in this paper, a matching method is proposed to evaluate the waveform of the measured change in wall thickness by comparing the measured waveform with a template waveform. The maximum deformation, which is used in the calculation of elasticity, was determined from the amplitude of the matched model waveform to reduce the influence of noise. The matched model waveform was obtained by minimizing the difference between the measured and template waveforms. Furthermore, a random error, which was obtained from the reproducibility among the heartbeats of the measured waveform, was considered useful for the evaluation of the reliability of the measured waveform.

  13. Diffusion capacity and CT measures of emphysema and airway wall thickness – relation to arterial oxygen tension in COPD patients

    Science.gov (United States)

    Saure, Eirunn Waatevik; Bakke, Per Sigvald; Eagan, Tomas Mikal Lind; Aanerud, Marianne; Jensen, Robert Leroy; Grydeland, Thomas Blix; Johannessen, Ane; Nilsen, Roy Miodini; Thorsen, Einar; Hardie, Jon Andrew

    2016-01-01

    Background Decreased diffusing capacity of the lung for carbon monoxide (DLCO) is associated with emphysema. DLCO is also related to decreased arterial oxygen tension (PaO2), but there are limited data on associations between PaO2 and computed tomography (CT) derived measures of emphysema and airway wall thickness. Objective To examine whether CT measures of emphysema and airway wall thickness are associated with level of arterial oxygen tension beyond that provided by measurements of diffusion capacity and spirometry. Methods The study sample consisted of 271 smoking or ex-smoking COPD patients from the Bergen COPD Cohort Study examined in 2007–2008. Emphysema was assessed as percent of low-attenuation areasCOPD patients. Emphysema score measured by chest CT, is related to decreased PaO2, but cannot replace measurements of diffusion capacity in the clinical evaluation of hypoxaemia. PMID:27178139

  14. Dual stack black blood carotid artery CMR at 3T: Application to wall thickness visualization

    Directory of Open Access Journals (Sweden)

    Marx Nikolaus

    2009-11-01

    Full Text Available Abstract Background The increasing understanding of atherosclerosis as an important risk factor for the development of acute ischemic events like ischemic stroke has stimulated increasing interest in non-invasive assessment of the structure, composition and burden of plaque depositions in the carotid artery wall. Vessel wall imaging by means of cardiovascular magnetic resonance (CMR is conventionally done by 2D dual inversion recovery (DIR techniques, which often fail in covering large volumes of interest as required in plaque burden assessment. Although the technique has been extended to 2D multislice imaging, its straight extension to 3D protocols is still limited by the prolonged acquisition times and incomplete blood suppression. A novel approach for rapid overview imaging of large sections of the carotid artery wall at isotropic spatial resolutions is presented, which omits excitation of the epiglottis. By the interleaved acquisition of two 3D stacks with the proposed motion sensitized segmented steady-state black-blood gradient echo technique (MSDS the coverage of the carotid artery trees on both sides in reasonable scan times is enabled. Results 10 patients were investigated with the proposed technique and compared to conventional transversal DIR turbo spin and gradient echo approaches centered at the height of the carotid bifurcation. In all MSDS experiments sufficient black-blood contrast could be obtained over the entire covered volumes. The contrast to noise ratio between vessel and suppressed blood was improved by 73% applying the motion sensitizing technique. In all patients the suspicious areas of vessel wall thickening could be clearly identified and validated by the conventional local imaging approach. The average assessable vessel wall segment length was evaluated to be 18 cm. While in 50% of the cases motion artifacts could be appreciated in the conventional images, none were detected for the MSDS technique. Conclusion The

  15. Portal venous arterialization resulting in increased portal inflow and portal vein wall thickness in rats

    Institute of Scientific and Technical Information of China (English)

    Wen-Gang Li; Yong-Liang Chen; Jing-Xi Chen; Lei Qu; Bin-Dang Xue; Zhi-Hai Peng; Zhi-Qiang Huang

    2008-01-01

    AIM:To explore the influence of portal vein hemodynamic changes after portal venous arterialization(PVA) on peribiliary vascular plexus (PVP)morphological structure and hepatic pathology,and to establish a theoretical basis for the clinical application of PVA.METHODS:Sprague-Dawley rats were randomly divided into control and PVA groups.After PVA,hemodynamic changes of the portal vein and morphological structure of hepatohilar PVP were observed using Doppler ultrasound,liver function tests,ink perfusion transparency management and three-dimensional reconstruction of computer microvisualization,and pathological examination was performed on tissue from the bile duct wall and the liver.RESULTS:After PVA,the cross-sectional area and blood flow of the portal vein were increased,and the increase became more significant over time,in a certain range.If the measure to limit the flow in PVA was not adopted,the high blood flow would lead to dilatation of intrahepatic portal vein and its branches,increase in collagen and fiber degeneration in tunica intima.Except glutamic pyruvic transaminase (GPT),other liver function tests were normal.CONCLUSION:Blood with a certain flow and oxygen content is important for filling the PVP and meeting the oxygen requirement of the bile duct wall.After PVA,It is the anatomic basis to maintain normal morphology of hepatohilar bile duct wall that the blood with high oxygen content and high flow in arterialized portal vein may fill PVP by collateral vessel reflux.A adequate measure to limit blood flow is necessary in PVA.

  16. Measurement of Change in Wall Thickness of Cylindrical Shell Due to Cyclic Remote Actuation for Assessment of Viscoelasticity of Arterial Wall

    Science.gov (United States)

    Hasegawa, Hideyuki; Kanai, Hiroshi; Koiwa, Yoshiro; Butler, James P.

    2003-05-01

    To characterize tissues in atherosclerotic plaques, we have developed a method, the phased tracking method, for measuring the strain (change in wall thickness) and elasticity of the arterial wall. However, some types of tissue, such as lipids and blood clots, cannot be discriminated from each other based only on elasticity because of the small difference in their elasticity. For more precise tissue characterization, we are attempting to measure the regional viscoelasticity. To determine viscoelastic properties, elastic moduli at multiple frequencies were obtained by generating the change in internal pressure due to remote cyclic actuation. From basic experiments using a silicone rubber tube, it was found that the change in internal pressure at the ultrasonic beam position (for measurement of the elastic modulus) can be generated by remotely applied actuation. Furthermore, from the resultant minute changes in wall thickness of less than 10 μm measured by the phased tracking method, elastic moduli were obtained at multiple actuation frequencies.

  17. Comparison between Carotid Artery Wall Thickness Measured by Multidetector Row Computed Tomography Angiography and Intimae-Media Thickness Measured by Sonography

    Directory of Open Access Journals (Sweden)

    Živorad N. Savić

    2011-01-01

    Full Text Available The increased thickness of the carotid wall >1 mm is a significant predictor of coronary and cerebrovascular diseases. The purpose of our study was to assess the agreement between multidetector row computed tomography angiography (MDCTA in measuring carotid artery wall thickness (CAWT and color Doppler ultrasound (CD-US in measuring intimae-media thickness (IMT. Eighty-nine patients (aged 35–81 were prospectively analyzed using a 64-detector MDCTA and a CD-US scanner. Continuous data were described as the mean value ± standard deviation, and were compared using the Mann–Whitney U test. A p value <0.05 was considered significant. Bland–Altman statistics were employed to measure the agreement between MDCTA and CD-US. CAWT ranged from 0.62 to 1.60 mm, with a mean value of 1.09 mm. IMT ranged from 0.60 to 1.55 mm, with a mean value of 1.06 mm. We observed an excellent agreement between CD-US and MDCTA in the evaluation of the common carotid artery thickness, with a bias between methods of 0.029 mm (which is a highly statistically important difference of absolute values [t = 43.289; p < 0.01] obtained by paired T test, and limits of agreement from 0.04 to 0.104. Pearson correlation coefficient was 0.9997 (95% CI 0.9996–0.9998; p < 0.01. We conclude that there is an excellent correlation between CAWT and IMT measurements obtained with the MDCTA and CD-US.

  18. The impact of exercise training on conduit artery wall thickness and remodeling in chronic heart failure patients

    NARCIS (Netherlands)

    Maiorana, A.J.; Naylor, L.H.; Exterkate, A.; Swart, A.; Thijssen, D.H.J.; Lam, K.; O'Driscoll, G.; Green, D.J.

    2011-01-01

    Exercise training is an important adjunct to medical therapy in chronic heart failure, but the extent to which exercise impacts on conduit artery remodeling is unknown. The aim of this study was to evaluate the impact of aerobic and resistance exercise training modalities on arterial remodeling in p

  19. Correlations of coronary plaque wall thickness with wall pressure and wall pressure gradient: a representative case study

    OpenAIRE

    Liu Biyue; Zheng Jie; Bach Richard; Tang Dalin

    2012-01-01

    Abstract Background There are two major hemodynamic stresses imposed at the blood arterial wall interface by flowing blood: the wall shear stress (WSS) acting tangentially to the wall, and the wall pressure (WP) acting normally to the wall. The role of flow wall shear stress in atherosclerosis progression has been under intensive investigation, while the impact of blood pressure on plaque progression has been under-studied. Method The correlations of wall thickness (WT) with wall pressure (WP...

  20. Cigarette smoking in military pilots and intima-media thickness of the carotid arteries

    OpenAIRE

    Jovelić Stojan; Hajduković Zoran; Jovelić Aleksandra; Rađen Slavica

    2005-01-01

    Background. It is well known that smoking is associated with an increase in arterial wall thickness. However, most studies of this problem have been undertaken in age and sex heterogeneous groups, as well as in patients with already present other conventional risk factors. The aim of this study was to assess the effect of cigarette smoking on arterial wall thickness of the common carotid artery in asymptomatic pilots. Methods. The imaging of intima−media thickness of the posterior wall of the...

  1. Turbine airfoil with outer wall thickness indicators

    Science.gov (United States)

    Marra, John J; James, Allister W; Merrill, Gary B

    2013-08-06

    A turbine airfoil usable in a turbine engine and including a depth indicator for determining outer wall blade thickness. The airfoil may include an outer wall having a plurality of grooves in the outer surface of the outer wall. The grooves may have a depth that represents a desired outer surface and wall thickness of the outer wall. The material forming an outer surface of the outer wall may be removed to be flush with an innermost point in each groove, thereby reducing the wall thickness and increasing efficiency. The plurality of grooves may be positioned in a radially outer region of the airfoil proximate to the tip.

  2. Practical considerations in ultrasonic wall thickness measurement

    International Nuclear Information System (INIS)

    Ultrasonic inspection is widely used by industry for the detection of corrosion and the measurement of material wall thickness. Due to wall thinning and the various forms of corrosion that can be found in pressure piping and pressure vessels the annual cost of corrosion damage and related service failures, is very expensive. The author interest is primarily in the examination of personnel who need to become competent and certificated in the various skills that are required to carry out wall thickness measurement and detection of wall thinning due to corrosion. The various techniques and equipment available for ultrasonic wall thickness measurement and assessment give rise to problems regarding the accuracy of results and detection of corrosion. This paper will discuss some of the corrosion conditions that may occur and also problems that may arise during wall thickness measurement. Methods of improving the wall thickness measurement and the assessment process will also be discussed. (author)

  3. Ultrasonic wall thickness measurement without coupling liquid

    International Nuclear Information System (INIS)

    If the material measured is part of the ultrasonic transducer, then one can do without the usual coupling liquid for ultrasonic measurement of wall thickness. Measuring equipment works on the basis of this electro-dynamic ultrasonic transducer, which has been developed to check the wall thickness (3 to 30 mm) of steel pipes with outside diameters of 25 to 180 mm. Double errors and local changes of wall thickness can be detected. (orig.)

  4. Arterial Wall Properties and Womersley Flow in Fabry Disease

    Directory of Open Access Journals (Sweden)

    Dimitriadis Emilios

    2002-01-01

    Full Text Available Abstract Background Fabry disease is an X-linked recessive lysosomal storage disease resulting in the cellular accumulation of globotriaosylceramide particularly globotriaosylceramide. The disease is characterized by a dilated vasculopathy with arterial ectasia in muscular arteries and arterioles. Previous venous plethysomographic studies suggest enhanced endothelium-dependent vasodilation in Fabry disease indicating a functional abnormality of resistance vessels. Methods We examined the mechanical properties of the radial artery in Fabry disease, a typical fibro-muscular artery. Eight control subjects and seven patients with Fabry disease had a right brachial arterial line placed allowing real time recording of intra-arterial blood pressure. Real time B-mode ultrasound recordings of the right radial artery were obtained simultaneously allowing calculation of the vessel wall internal and external diameter, the incremental Young's modulus and arterial wall thickness. By simultaneously measurement of the distal index finger-pulse oximetry the pulse wave speed was calculated. From the wave speed and the internal radial artery diameter the volume flow was calculated by Womersley analysis following truncation of the late diastolic phase. Results No significant difference was found between Fabry patients and controls for internal or external arterial diameters, the incremental Young's modulus, the arterial wall thickness, the pulse wave speed and the basal radial artery blood flow. Further, no significant difference was found for the radial artery blood flow in response to intra-arterial acetylcholine or sodium nitroprusside. Both drugs however, elevated the mean arterial flow. Conclusions The current study suggests that no structural or mechanical abnormality exists in the vessel wall of fibro-muscular arteries in Fabry disease. This may indicate that a functional abnormality downstream to the conductance vessels is the dominant feature in

  5. Determination of arterial wall shear stress

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The arteries can remodel their structure and function to adapt themselves to the mechanical environment. In various factors that lead to vascular remodeling, the shear stress on the arterial wall induced by the blood flow is of great importance. However, there are many technique difficulties in measuring the wall shear stress directly at present. In this paper, through analyzing the pulsatile blood flow in arteries, a method has been proposed that can determine the wall shear stress quantitatively by measuring the velocity on the arterial axis, and that provides a necessary means to discuss the influence of arterial wall shear stress on vascular remodeling.

  6. Artery Wall Imaging and Effects of Postmenopausal Estrogen Therapy

    OpenAIRE

    Rodriguez-Macias Wallberg, Kenny A.

    2005-01-01

    Postmenopausal estrogen therapy, initiated early in the menopause, seems to protect against development of atherosclerosis and cardiovascular diseases. This thesis concerns studies of artery wall thickness and arterial stiffness estimated by noninvasive ultrasound techniques in long-term estrogen treated postmenopausal women who initiated therapy at the time of the menopause. A noninvasive 25 MHz high-frequency ultrasound technique was validated in the imaging of superficial arteries by using...

  7. ON WALL SHEAR STRESS OF ARTERY

    Institute of Scientific and Technical Information of China (English)

    Liu Zhao-rong; Liu Bao-yu; Qin Kai-rong

    2003-01-01

    In this paper, a method was proposed that the wall shear stress of artery could be determined by measuring the centerline axial velocity and radial motion of arterial wall simultaneously.The method is simple in application and can get higher precision when it is used to determine the shear stress of arterial wall in vivo.As an example, the shear stress distribution in periodic oscillatory flow of human carotid was calculated and discussed.The computed results show that the shear stress distribution at any given instant is almost uniform and will be zero at the centerline and tends to maximum at the vessel wall.

  8. Correlations of coronary plaque wall thickness with wall pressure and wall pressure gradient: a representative case study

    Directory of Open Access Journals (Sweden)

    Liu Biyue

    2012-07-01

    Full Text Available Abstract Background There are two major hemodynamic stresses imposed at the blood arterial wall interface by flowing blood: the wall shear stress (WSS acting tangentially to the wall, and the wall pressure (WP acting normally to the wall. The role of flow wall shear stress in atherosclerosis progression has been under intensive investigation, while the impact of blood pressure on plaque progression has been under-studied. Method The correlations of wall thickness (WT with wall pressure (WP, blood pressure on the lumen wall and spatial wall pressure gradient (WPG in a human atherosclerotic right coronary artery were studied. The pulsatile blood flow was simulated using a three dimensional mathematical model. The blood was treated as an incompressible viscous non-Newtonian fluid. The geometry of the artery was re-constructed using an in vivo intravascular ultrasound (IVUS 44-slice dataset obtained from a patient with consent obtained. The WT, the WP and the WPG were averaged on each slice, respectively, and Pearson correlation analysis was performed on slice averaged base. Each slice was then divided into 8 segments and averaged vessel WT, WP and WPG were collected from all 352 segments for correlation analysis. Each slice was also divided into 2 segments (inner semi-wall of bend and outer semi-wall of bend and the correlation analysis was performed on the 88 segments. Results Under mean pressure, the Pearson coefficient for correlation between WT and WP was r = − 0.52 (p  Conclusions Results from this representative case report indicated that plaque wall thickness correlated negatively with wall pressure (r = −0.81 by slice and positively with wall pressure gradient (r = 0.45. The slice averaged WT has a strong linear relationship with the slice averaged WP. Large-scale patient studies are needed to further confirm our findings.

  9. Common carotid artery wall thickness and external diameter as predictors of prevalent and incident cardiac events in a large population study

    Directory of Open Access Journals (Sweden)

    Bursac Zoran

    2007-03-01

    Full Text Available Abstract Background Arterial diameters enlarge in response to wall thickening, plaques, and many atherosclerotic risk factors. We hypothesized that right common carotid artery (RCCA diameter would be independently associated with cardiac disease and improve risk discrimination. Methods In a middle-aged, biracial population (baseline n = 11225, we examined associations between 1 standard deviation increments of baseline RCCA diameter with prevalent myocardial infarction (MI and incident cardiac events (MI or cardiac death using logistic regression and Cox proportional hazards models, respectively. Areas under the receiver operator characteristic curve (AUC were used to estimate model discrimination. Results MI was present in 451 (4% participants at baseline (1987–89, and incident cardiac events occurred among 646 (6% others through 1999. Adjusting for IMT, RCCA diameter was associated with prevalent MI (female OR = 2.0, 95%CI = 1.61–2.49; male OR = 1.16, 95% CI = 1.04–1.30 and incident cardiac events (female HR = 1.75, 95% CI = 1.51–2.02; male HR = 1.27, 95% CI = 1.15–1.40. Associations were attenuated but persisted after adjustment for risk factors (not including IMT (prevalent MI: female OR = 1.73, 95% CI = 1.40–2.14; male OR = 1.14, 95% CI = 1.02–1.28, and incident cardiac events: female HR = 1.26, 95% CI = 1.08–1.48; male HR = 1.19, 95% CI = 1.08–1.32. After additional adjustment for IMT, diameter was associated with incident cardiac events in women (HR = 1.18, 95% CI = 1.00–1.40 and men (HR = 1.17, 95% CI = 1.06–1.29, and with prevalent MI only in women (OR = 1.73; 95% CI = 1.37–2.17. In women, when adjustment was limited, diameter models had larger AUC than other models. Conclusion RCCA diameter is an important correlate of cardiac events, independent of IMT, but adds little to overall risk discrimination after risk factor adjustment.

  10. Relationship of sonographic wall components of the brachial artery to hypertension and coronary atherosclerosis

    OpenAIRE

    Frick, Matthias; Alber, Hannes F; Rinner, Alexander; Suessenbacher, Alois; Ulmer, Hanno; Schwarzacher, Severin P; Pachinger, Otmar; Weidinger, Franz

    2005-01-01

    Abstract The aim of this study was to determine whether sonographically assessed intimal (echodense, ED) or medial (echolucent, EL) thickening of the brachial artery is associated with coronary artery disease (CAD) and/or arterial hypertension (HT). In 201 patients the ED and EL wall components, as well as the total wall thickness of the brachial artery, were measured with high-resolution ultrasound (13 MHz). According to the presence or absence of CAD and HT, the patients were div...

  11. On thick domain walls in general relativity

    Science.gov (United States)

    Goetz, Guenter; Noetzold, Dirk

    1989-01-01

    Planar scalar field configurations in general relativity differ considerably from those in flat space. It is shown that static domain walls of finite thickness in curved space-time do not possess a reflection symmetry. At infinity, the space-time tends to the Taub vacuum on one side of the wall and to the Minkowski vacuum (Rindler space-time) on the other. Massive test particles are always accelerated towards the Minkowski side, i.e., domain walls are attractive on the Taub side, but repulsive on the Minkowski side (Taub-vacuum cleaner). It is also proved that the pressure in all directions is always negative. Finally, a brief comment is made concerning the possibility of infinite, i.e., bigger than horizon size, domain walls in our universe. All of the results are independent of the form of the potential V(phi) greater than or equal to 0 of the scalar field phi.

  12. Sonographic assessment of splanchnic arteries and the bowel wall

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, C.F. [Medical Department II, Caritas-Krankenhaus, Uhlandstr. 7, D-97980 Bad Mergentheim (Germany)], E-mail: Christoph.dietrich@ckbm.de; Jedrzejczyk, M.; Ignee, A. [Medical Department II, Caritas-Krankenhaus, Uhlandstr. 7, D-97980 Bad Mergentheim (Germany)

    2007-11-15

    The intestinal wall can be visualized using high resolution transabdominal ultrasound. The normal intestinal wall thickness in the terminal ileum, cecum, and right and left colon is <2 mm when examined with graded compression. It is important to appreciate that a contracted intestinal segment can be misinterpreted as a thickened wall. Vascularisation can be mainly displayed in the second hyperechoic layer (submucosal layer) as well as vessels penetrating the muscularis propria. Imaging of the gastrointestinal wall is dependent on the experience of the examiner as well dependent on the equipment used. Acute or chronic inflammation of the intestinal wall is accompanied by increased perfusion of the mesentery, which can be displayed non-quantitatively with colour duplex. In contrast, ischemia is characterised by hypoperfusion of the mesenteric arteries and the bowel wall. The most promising sonographic approach in assessing splanchnic arteries and the bowel wall is combining the analysis of superior and inferior mesenteric inflow by pulsed Doppler scanning (systolic and diastolic velocities, resistance index) with the end-organ vascularity by colour Doppler imaging diminishing the influence of examination technique only displaying bowel wall vascularity. Colour Doppler imaging has been described as helpful in a variety of gastrointestinal disorders, particularly in patients with Crohn's disease, celiac disease, mesenteric artery stenosis and other ischemic gastrointestinal diseases, graft versus host disease and hemorrhagic segmental colitis.

  13. Sonographic assessment of splanchnic arteries and the bowel wall

    International Nuclear Information System (INIS)

    The intestinal wall can be visualized using high resolution transabdominal ultrasound. The normal intestinal wall thickness in the terminal ileum, cecum, and right and left colon is <2 mm when examined with graded compression. It is important to appreciate that a contracted intestinal segment can be misinterpreted as a thickened wall. Vascularisation can be mainly displayed in the second hyperechoic layer (submucosal layer) as well as vessels penetrating the muscularis propria. Imaging of the gastrointestinal wall is dependent on the experience of the examiner as well dependent on the equipment used. Acute or chronic inflammation of the intestinal wall is accompanied by increased perfusion of the mesentery, which can be displayed non-quantitatively with colour duplex. In contrast, ischemia is characterised by hypoperfusion of the mesenteric arteries and the bowel wall. The most promising sonographic approach in assessing splanchnic arteries and the bowel wall is combining the analysis of superior and inferior mesenteric inflow by pulsed Doppler scanning (systolic and diastolic velocities, resistance index) with the end-organ vascularity by colour Doppler imaging diminishing the influence of examination technique only displaying bowel wall vascularity. Colour Doppler imaging has been described as helpful in a variety of gastrointestinal disorders, particularly in patients with Crohn's disease, celiac disease, mesenteric artery stenosis and other ischemic gastrointestinal diseases, graft versus host disease and hemorrhagic segmental colitis

  14. Cigarette smoking in military pilots and intima-media thickness of the carotid arteries

    Directory of Open Access Journals (Sweden)

    Jovelić Stojan

    2005-01-01

    Full Text Available Background. It is well known that smoking is associated with an increase in arterial wall thickness. However, most studies of this problem have been undertaken in age and sex heterogeneous groups, as well as in patients with already present other conventional risk factors. The aim of this study was to assess the effect of cigarette smoking on arterial wall thickness of the common carotid artery in asymptomatic pilots. Methods. The imaging of intima−media thickness of the posterior wall of the distal 1 cm of both common carotid arteries was performed using a B mode ultrasound device, in 39 pilots (37.05 ± 6.66 years, for whom smoking was the single cardiovascular risk factor. Comparisons were made with 49 non-smokers (35.12 ± 7.39 years. Results. The posterior walls of both common carotid arteries were thicker in smokers (left, p < 0.05; right, p > 0,05. Intima-media thickness was significantly lower on the right side than on the left side in both smokers and nonsmokers (p < 0.01. Conclusion. Cigarette smoking as the single cardiovascular risk factor was associated with the wall thickness of the carotid arteries in our study. This finding indicated that early atherosclerosis was already present in pilots - smokers entering middle age.

  15. A New High-Resolution Spectral Approach to Noninvasively Evaluate Wall Deformations in Arteries

    OpenAIRE

    Ivonne Bazan; Carlos Negreira; Antonio Ramos; Javier Brum; Alfredo Ramirez

    2014-01-01

    By locally measuring changes on arterial wall thickness as a function of pressure, the related Young modulus can be evaluated. This physical magnitude has shown to be an important predictive factor for cardiovascular diseases. For evaluating those changes, imaging segmentation or time correlations of ultrasonic echoes, coming from wall interfaces, are usually employed. In this paper, an alternative low-cost technique is proposed to locally evaluate variations on arterial walls, which are dyna...

  16. New portable pipe wall thickness measuring technique

    Science.gov (United States)

    Pascente, Joseph E.

    1998-03-01

    One of the biggest inspection challenges facing many of the process industries; namely the petrochemical, refining, fossil power, and pulp and paper industries is: How to effectively examine their insulated piping? While there are a number of failure mechanisms involved in various process piping systems, piping degradation through corrosion and erosion are by far the most prevalent. This degradation can be in the form of external corrosion under insulation, internal corrosion through a variety of mechanisms, and internal erosion caused by the flow of the product through the pipe. Refineries, chemical plants and electrical power plants have MANY thousands of miles of pipe that are insulated to prevent heat loss or heat absorption. This insulation is often made up of several materials, with calcium based material being the most dense. The insulating material is usually wrapped with an aluminum or stainless steel outer wrap. Verification of wall thickness of these pipes can be accomplished by removing the insulation and doing an ultrasound inspection or by taking x- rays at a tangent to the edge of the pipe through the insulation. Both of these processes are slow and expensive. The time required to obtain data is measured in hours per meter. The ultrasound method requires that the insulation be plugged after the inspection. The surface needs to be cleaned or the resulting data will not be accurate. The tangent x-ray only shows two thicknesses and requires that the area be roped off because of radiation safety.

  17. Carotid Artery Segmentation in Ultrasound Images and Measurement of Intima-Media Thickness

    OpenAIRE

    Vaishali Naik; R.S. Gamad; P.P. Bansod

    2013-01-01

    Background. The segmentation of the common carotid artery (CCA) wall is imperative for the determination of the intima-media thickness (IMT) on B-mode ultrasound (US) images. The IMT is considered an important indicator in the evaluation of the risk for the development of atherosclerosis. In this paper, authors have discussed the relevance of measurements in clinical practices and the challenges that one has to face while approaching the segmentation of carotid artery on ultrasound images. Th...

  18. Sonographic gallbladder wall thickness in normal adult population in Nigeria

    OpenAIRE

    Mohammed, S; Tahir, A.; A Ahidjo; Z Mustapha; Franza O

    2010-01-01

    Aim. The aim of the study was to determine the ultrasonic gallbladder wall thickness in normal adult Nigerians so as to create standards for defining gallbladder abnormalities in Nigerians. Method. Four hundred adults comprising 228 (57%) women and 172 (43%) men aged 16 - 78 years, who had normal clinical history and physical findings, were recruited. The gallbladder wall thickness was obtained in the supine, prone and right anterior oblique positions. Differences in gallbladder wall thick...

  19. Biometric estimation of chest wall thickness of females

    International Nuclear Information System (INIS)

    Optimal use of whole-body counting data to estimate pulmonary deposition of many of the actinides is dependent upon accurate measurement of the thickness of the chest wall because of severe attenuation of low-energy x rays and photons associated with the decay of these radionuclides. An algorithm for estimation of female chest wall thicknesses, verified by real-time ultrasonic measurements, has been derived based on the correlation of measured chest wall thickness and other common biometric quantities. Use of this algorithm will reduce the error generally associated with estimation of internal actinide deposition previously resulting from assuming an average chest wall thickness for all female subjects

  20. Consistence study of carotid artery wall thickness by MDCTA and high-frequency ultrasound%MDCTA与高频超声检测颈动脉壁厚度的一致性研究

    Institute of Scientific and Technical Information of China (English)

    洪玮; 赵刚; 王弘; 邱晓明; 王珍

    2012-01-01

    Objective To explore the relevance and consistence between multi-detector row computed tomography angi-ography (MDCTA) and high-frequency ultrasound in measuring carotid artery wall thickness (CAWT) and the intima-media thickness (IMT). Methods Altogether, 64 subjects were prospectively analysed using a 64-detector row CT and high-frequency ultrasound. And they were classified as non-plaque group and plaque group. CAWT and IMT were measured in each patient using MDCTA and ultrasound, respectively. CAWT and IMT were compared and dependency analysed. Bland-Altman statistics was employed to measure the consistency between MDCTA and ultrasound. Results There was not significant difference between CAWT and IMT in the same group ( P > 0. 05). There was a high degree of correlation between all the common carotid artery CAWT and IMT, correlation coefficient was 0. 912 ( P <0. 01). By analysing the Bland-Altman plot, we observed a good consistence between CAWT and IMT with a bias between methods of 0. 029 mm and limit of consistence from 0. 187 mm to 0. 244 mm. Conclusion There was a good consistency between MDCTA and high-frequency ultrasound in the measurement of CAWT and IMT. CAWT can be used as an evaluating indicator of carotid atherosclerosis by MDCTA.%目的 探讨多层螺旋CT血管造影(MDCTA)检测颈总动脉壁厚度(CAWT)与高频超声检测颈总动脉内-中膜层厚度(IMT)的相关性和一致性.方法 应用MDCTA和高频超声对64例患者颈总动脉CAWT和IMT分别进行扫描,分为无斑块组和有斑块组,统计学比较CAWT与IMT的差异性和相关性,用Bland-Altman分析比较两者的一致性.结果 两组患者颈总动脉CAWT与IMT比较无统计学差异(P>0.05),相关性分析呈高度正相关,相关系数为0.912(P<0.O1),Bland-Altman分析存在较好一致性,偏倚为0.029mm,一致性界限为0.187~0.244mm.结论 MDCTA测量颈总动脉CAWT与高频超声测量颈总动脉IMT之间存在高度相关性和较好一致

  1. Estimates of elastic fracture mechanics parameters for thick walled pipes with slanted axial through wall cracks

    International Nuclear Information System (INIS)

    The present paper provides the elastic stress intensity factors (SIFs) and the crack opening displacements (CODs) of a thick walled pipe with a slanted axial through wall crack. For estimating these elastic fracture mechanics parameters, systematic three dimensional elastic finite element (FE) analyses were performed by considering geometric variables, i. e., thickness of pipe, reference crack length, and crack length ratio, affecting the SIFs and CODs. As for loading condition, the internal pressure was considered. Based on the FE results, the SIFs and CODs of slanted axial through wall cracks in a thick-walled pipe along the crack front and the wall thickness were calculated. In particular, to calculate the SIFs of a thick walled pipe with a slanted axial through wall crack from those of a thick walled pipe with an idealized axial through wall crack, a slant correction factor representing the effect of the slant crack on the SIFs was proposed

  2. Tube wall thickness guage for hot stretch reducer

    International Nuclear Information System (INIS)

    A new system of tube wall thickness gauge for seamless tube on hot stretch reducing-mill is reported. The system adapts two methods using gamma rays. One is a new method measuring double wall thickness of tube another is a known method measuring mean value of cross section of tube. (author)

  3. Intima-media thickness and arterial stiffness of carotid artery in Korean patients with Behçet's disease.

    Science.gov (United States)

    Rhee, Moo-Yong; Chang, Hyun Kyu; Kim, Seong-Kyu

    2007-06-01

    Behçet's disease (BD) is a systemic vasculitis involving diverse sizes of arteries and veins. We performed this study to evaluate the vascular changes by assessment of the arterial stiffness and intima-media thickness (IMT) of carotid artery in Korean patients with BD. Forty-one patients with BD and age-, and sex-matched 53 healthy subjects were recruited in this study. Carotid arterial stiffness and IMT were assessed by using high-resolution B-mode ultrasonography. Arterial stiffness parameters such as carotid arterial distensibility coefficient, stiffness index, and incremental elastic modulus (E(inc)) were significantly increased in BD patients compared with those in healthy subjects, but not in IMT. Positive relationship was noted between age and IMT, whereas age of onset was significantly associated with arterial stiffness in BD. This finding suggests impaired endothelial function before visible structural changes of arterial wall in BD. Age and age of onset may be an independent risk factor for carotid IMT and arterial stiffness, respectively. Further studies in more large populations are required to confirm our results. PMID:17596642

  4. Wall shear stress in intracranial aneurysms and adjacent arteries

    Institute of Scientific and Technical Information of China (English)

    Fuyu Wang; Bainan Xu; Zhenghui Sun; Chen Wu; Xiaojun Zhang

    2013-01-01

    Hemodynamic parameters play an important role in aneurysm formation and growth. However, it is difficult to directly observe a rapidly growing de novo aneurysm in a patient. To investigate possible associations between hemodynamic parameters and the formation and growth of intracranial aneurysms, the present study constructed a computational model of a case with an internal carotid artery aneurysm and an anterior communicating artery aneurysm, based on the CT angiography findings of a patient. To simulate the formation of the anterior communicating artery aneurysm and the growth of the internal carotid artery aneurysm, we then constructed a model that virtually removed the anterior communicating artery aneurysm, and a further two models that also progressively decreased the size of the internal carotid artery aneurysm. Computational simulations of the fluid dynamics of the four models were performed under pulsatile flow conditions, and wall shear stress was compared among the different models. In the three aneurysm growth models, increasing size of the aneurysm was associated with an increased area of low wall shear stress, a significant decrease in wall shear stress at the dome of the aneurysm, and a significant change in the wall shear stress of the parent artery. The wall shear stress of the anterior communicating artery remained low, and was significantly lower than the wall shear stress at the bifurcation of the internal carotid artery or the bifurcation of the middle cerebral artery. After formation of the anterior communicating artery aneurysm, the wall shear stress at the dome of the internal carotid artery aneurysm increased significantly, and the wall shear stress in the upstream arteries also changed significantly. These findings indicate that low wall shear stress may be associated with the initiation and growth of aneurysms, and that aneurysm formation and growth may influence hemodynamic parameters in the local and adjacent arteries.

  5. Comparison between multi-detector row CT angiography and Doppler ultrasound on detecting carotid artery wall thickness%多层螺旋CT与Doppler超声对颈动脉壁层厚度的对比性研究

    Institute of Scientific and Technical Information of China (English)

    赵刚; 查云飞; 王弘; 洪玮; 邱晓明; 王珍; 肖友梅

    2013-01-01

    Objective To explore the relationship and consistency between multi-detector row computed tomography angiography (MDCTA) and color Doppler ultrasound (CD-US) in measuring carotid artery wall thickness (CAWT) and intima-media thickness (IMT). Methods CAWT and IMT of 38 subjects were measured using MDCTA and CD-US, respectively. Linear correlation analysis was performed to analyze the correlation between the results from CAWT and IMT,and Bland-Altman statistics was employed to analyze the consistency between them. Results The IMT value measured by CD-US was (0.85+0.16) mm, and the CAWT value measured by MDCTA was (0.87.± 0.18) mm (P > 0.05), and there was a high degree of correlation between them (correlation coefficient was 0.958,P< 0.01). An excellent consistency between CAWT and IMT was found by Bland-Altman plot, with a bias of 0.026 mm and the limit of consistency from -0.023 to 0.075. Conclusions There were significant correlation and consistency between MDCTA and CD-US in detecting CAWT and IMT. As a more objective and comprehensive new method, MDCTA can replace CD-US in the evaluation of early carotid atherosclerosis.%目的:探讨多层螺旋CT血管造影(MDCTA)和彩色多普勒超声(CD-US)在检测颈总动脉壁厚度(CAWT)和颈总动脉内膜-中层厚度(IMT)中的相关性和一致性.方法:应用MDCTA和CD-US分别对38例受试者颈总动脉的CAWT和IMT进行检测,用Pearson直线相关分析比较CAWT和IMT的相关性,用Bland-Altman分析比较两者的一致性.结果:MDCTA测量的颈总动脉CAWT为(0.87±0.18)mm,CD-US测量的颈总动脉IMT为(0.85±0.16)mm,两者比较无统计学差异,有高度相关性,相关系数为0.958,P<0.01,Bland-Altman分析两者间存在良好一致性,偏倚为0.026 mm,一致性界限为-0.023 ~ 0.075.结论:MDCTA和CD-US在检测颈总动脉CAWT和IMT时存在良好的相关性和一致性,MDCTA可以替代CD-US,作为一种评价颈动脉早期粥样硬化的更加客观全面的新方法.

  6. Bladder Wall Thickness Mapping for Magnetic Resonance Cystography

    OpenAIRE

    Zhao, Yang; Liang, Zhengrong; Zhu, Hongbin; Han, Hao; Duan, Chaijie; Yan, Zengmin; Lu, Hongbing; Gu, Xianfeng

    2013-01-01

    Clinical studies have shown the evidence that the bladder wall thickness is an effective biomarker for bladder abnormalities. The clinical optical cystoscopy, the current gold standard, cannot show the wall thickness. The use of ultrasound by experts may generate some local thickness information, but the information is limited in field-of-view and is user dependent. Recent advances in magnetic resonance (MR) imaging technologies lead MR-based virtual cystoscopy or MR cystography toward a pote...

  7. Determination of arterial wall shear stress

    Institute of Scientific and Technical Information of China (English)

    LIU; Zhaorong

    2001-01-01

    [1]Langille, B. L., 7Donnell, F., Reductions in arterial diameter produced by chronic decreases in blood flow are endothelium-dependent, Science, 1986, 231: 405—407.[2]Langer, R., Vacanti, J. P., Tissue engineering, Science, 1993, 260: 920—926.[3]Kamiya, A., Togawa, T., Adaptive regulation of wall shear stress to flow change in the canine carotid artery, Am. J. Physiol. (Heart Circ. Physiol.), 1980, 239: H14—H21.[4]Fung, Y. C., Biomechanics: Motion, Flow, Stress, and Growth, New York: Springer-Verlag, 1990.[5]Liu, S. Q., Biomechanical basis of vascular tissue engineering, Critical Reviews in Biomedical Engineering, 1999, 27: 75—148.[6]Ando, J., Kamiya, A., Blood flow and vascular endothelium cell function, Frontiers Med. Biological Eng., 1993, 5: 245—264.[7]Ku, D. N., Giddens, D. P., Zarins, D. K. et al., Pulsatile flow and atherosclerosis in the human carotid bifurcation-positive correlation between plaque location and low and oscillating shear stress, Atherosclerosis, 1985, 5: 293—302.[8]Liu Zhaorong, Li Xixi, Theory and Method on Hemodynamics (in Chinese), Shanghai: Fudan University Press, 1997.

  8. Diabetes Mellitus, ArterialWall, and Cardiovascular Risk Assessment

    OpenAIRE

    Michaela Kozakova; Carlo Palombo

    2016-01-01

    Diabetes mellitus is an independent risk factor for atherothrombotic cardiovascular disease. Adults with diabetes are two to four times more likely to develop heart disease or stroke than adults without diabetes. The two major features of diabetes, i.e., hyperglycemia and insulin-resistance, trigger arterial stiffening and increase the susceptibility of the arterial wall to atherosclerosis at any given age. These pathological changes in the arterial wall may provide a functional and structura...

  9. Sonographic gallbladder wall thickness in normal adult population in Nigeria

    Directory of Open Access Journals (Sweden)

    S Mohammed

    2010-12-01

    Full Text Available Aim. The aim of the study was to determine the ultrasonic gallbladder wall thickness in normal adult Nigerians so as to create standards for defining gallbladder abnormalities in Nigerians. Method. Four hundred adults comprising 228 (57% women and 172 (43% men aged 16 - 78 years, who had normal clinical history and physical findings, were recruited. The gallbladder wall thickness was obtained in the supine, prone and right anterior oblique positions. Differences in gallbladder wall thickness were determined using the chi-square test, while the relationship between the ultrasound-measured gallbladder wall thickness and the subjects’ age, sex, height and weight were analysed using the Pearson product moment correlation. Normal ranges and related statistics were estimated and tabulated according to age group and sex. Results. The mean age of the subjects was 32±13.2 years. The mean gallbladder wall thickness range was 1.8 - 2.8 mm±0.5mm. The thickness range for females was 1.7 - 2.7 mm±0.5 mm, and that for males was 1.9 - 2.9 mm±0.5 mm. There was a statistically significant difference (p<0.05 in the mean wall thickness between males and females. The mean body parameters (height, weight of males were significantly greater than those of females (p<0.047, p<0.000 respectively. There was no correlation between gallbladder wall thickness and age and height of subjects (r=0.34, p<0.09. Conclusion. Our study was able to establish population-specific ultrasonic values for gallbladder wall thickness in normal adults that can be reliably used as standard to define gallbladder abnormalities in Nigerians.

  10. Accurate wall thickness measurement using autointerference of circumferential Lamb wave

    International Nuclear Information System (INIS)

    In this paper, a method of accurately measuring the pipe wall thickness by using noncontact air-coupled ultrasonic transducer (NAUT) was presented. In this method, accurate measurement of angular wave number (AWN) is a key technique because the AWN is changes minutely with the wall thickness. An autointerference of the circumferential (C-) Lamb wave was used for accurate measurements of the AWN. Principle of the method was first explained. Modified method for measuring the wall thickness near a butt weld line was also proposed and its accuracy was evaluated within 6 μm error. It was also shown in the paper that wall thickness measurement was accurately carried out beyond the difference among the sensors by calibrating the frequency response of the sensors. (author)

  11. Evaluation of Tube Wall Thickness of Feed Water Heater

    Science.gov (United States)

    Uchikura, Takahisa; Morisaki, Koichi; Hamada, Seiichi

    With regard to the high pressure (HP) feed water heater of thermal power plant at Tokyo Electric Power Company (TEPCO) sites, inspection of feed water (FW) tubes wall thickness are conducted whenever required such that frequent tube leak occurs. As a standard inspection methodology, FW heater is disassembled during planned outage, tube wall thickness is measured by the ultrasonic pulse techique (UT), then plugs are installed at the both ends of FW tube if its measured wall thickness is found below calculated threshold. However, the root causes of wall thinning of FW tube are various such as erosion and corrosion, based on wall thinning condition, the above threshold is not applied but utilizing the other technically well-grounded evaluation method is sometimes more rational. Therefore, TEPCO classified wall-thinning condition based on inspection data and established technically well-grounded and rational evaluation methodologies of FW tube wall thickness to suite each wall thinning condition. Moreover, with recent improvement of inspection technique, technology enabled faster, larger amount, and more accurate data acquisition, TEPCO has developed the systematized evaluation methodology that can transact data acquisition and evaluation simultaneously. This article introduces the logic of evaluation methods and examined algorithms to make them systematized.

  12. Measurement of pipe wall local thickness by combined radiation method

    International Nuclear Information System (INIS)

    Analytical dependences have been studied which describe radiation fluxes registered by the respective detectors during transmission of a collimated beam of penetrating radiation through a tube over its diameter. The dependences are necessary for engineering designs, analysis of accuracy and other characteristics of radioisotope thickness gaUges using the combined method for measurements of tube wall local thickness. Experimental investigations have been carried out with 137Cs and 60Co sources. The dependence, permitting to determine conditions providing with the preset accuracy of tube wall local thickness measurement by the combined method, has been obtained

  13. Parametric Investigation of Optimum Thermal Insulation Thickness for External Walls

    Directory of Open Access Journals (Sweden)

    Omer Kaynakli

    2011-06-01

    Full Text Available Numerous studies have estimated the optimum thickness of thermal insulation materials used in building walls for different climate conditions. The economic parameters (inflation rate, discount rate, lifetime and energy costs, the heating/cooling loads of the building, the wall structure and the properties of the insulation material all affect the optimum insulation thickness. This study focused on the investigation of these parameters that affect the optimum thermal insulation thickness for building walls. To determine the optimum thickness and payback period, an economic model based on life-cycle cost analysis was used. As a result, the optimum thermal insulation thickness increased with increasing the heating and cooling energy requirements, the lifetime of the building, the inflation rate, energy costs and thermal conductivity of insulation. However, the thickness decreased with increasing the discount rate, the insulation material cost, the total wall resistance, the coefficient of performance (COP of the cooling system and the solar radiation incident on a wall. In addition, the effects of these parameters on the total life-cycle cost, payback periods and energy savings were also investigated.

  14. Serum carotenoids reduce progression of early atherosclerosis in the carotid artery wall among Eastern Finnish men.

    Directory of Open Access Journals (Sweden)

    Jouni Karppi

    Full Text Available BACKGROUND: Several previous epidemiologic studies have shown that high blood levels of carotenoids may be protective against early atherosclerosis, but results have been inconsistent. We assessed the association between atherosclerotic progression, measured by intima-media thickness of the common carotid artery wall, and serum levels of carotenoids. METHODS: We studied the effect of carotenoids on progression of early atherosclerosis in a population-based study. The association between concentrations of serum carotenoids, and intima-media thickness of the common carotid artery wall was explored in 840 middle-aged men (aged 46-65 years from Eastern Finland. Ultrasonography of the common carotid arteries were performed at baseline and 7-year follow-up. Serum levels of carotenoids were analyzed at baseline. Changes in mean and maximum intima media thickness of carotid artery wall were related to baseline serum carotenoid levels in covariance analyses adjusted for covariates. RESULTS: In a covariance analysis with adjustment for age, ultrasound sonographer, maximum intima media thickness, examination year, body mass index, systolic blood pressure, smoking, physical activity, serum LDL cholesterol, family history of coronary heart disease, antihypertensive medication and serum high sensitivity C-reactive protein, 7-year change in maximum intima media thickness was inversely associated with lycopene (p = 0.005, α-carotene (p = 0.002 and β-carotene (p = 0.019, respectively. CONCLUSIONS: The present study shows that high serum concentrations of carotenoids may be protective against early atherosclerosis.

  15. Bladder wall thickness mapping for magnetic resonance cystography

    International Nuclear Information System (INIS)

    Clinical studies have shown evidence that the bladder wall thickness is an effective biomarker for bladder abnormalities. Clinical optical cystoscopy, the current gold standard, cannot show the wall thickness. The use of ultrasound by experts may generate some local thickness information, but the information is limited in field-of-view and is user dependent. Recent advances in magnetic resonance (MR) imaging technologies lead MR-based virtual cystoscopy or MR cystography toward a potential alternative to map the wall thickness for the entire bladder. From a high-resolution structural MR volumetric image of the abdomen, a reasonable segmentation of the inner and outer borders of the bladder wall can be achievable. Starting from here, this paper reviews the limitation of a previous distance field-based approach of measuring the thickness between the two borders and then provides a solution to overcome the limitation by an electric field-based strategy. In addition, this paper further investigates a surface-fitting strategy to minimize the discretization errors on the voxel-like borders and facilitate the thickness mapping on the three-dimensional patient-specific bladder model. The presented thickness calculation and mapping were tested on both phantom and human subject datasets. The results are preliminary but very promising with a noticeable improvement over the previous distance field-based approach. (paper)

  16. Bladder wall thickness mapping for magnetic resonance cystography

    Science.gov (United States)

    Zhao, Yang; Liang, Zhengrong; Zhu, Hongbin; Han, Hao; Duan, Chaijie; Yan, Zengmin; Lu, Hongbing; Gu, Xianfeng

    2013-08-01

    Clinical studies have shown evidence that the bladder wall thickness is an effective biomarker for bladder abnormalities. Clinical optical cystoscopy, the current gold standard, cannot show the wall thickness. The use of ultrasound by experts may generate some local thickness information, but the information is limited in field-of-view and is user dependent. Recent advances in magnetic resonance (MR) imaging technologies lead MR-based virtual cystoscopy or MR cystography toward a potential alternative to map the wall thickness for the entire bladder. From a high-resolution structural MR volumetric image of the abdomen, a reasonable segmentation of the inner and outer borders of the bladder wall can be achievable. Starting from here, this paper reviews the limitation of a previous distance field-based approach of measuring the thickness between the two borders and then provides a solution to overcome the limitation by an electric field-based strategy. In addition, this paper further investigates a surface-fitting strategy to minimize the discretization errors on the voxel-like borders and facilitate the thickness mapping on the three-dimensional patient-specific bladder model. The presented thickness calculation and mapping were tested on both phantom and human subject datasets. The results are preliminary but very promising with a noticeable improvement over the previous distance field-based approach.

  17. Evolution of thick domain walls in de Sitter universe

    CERN Document Server

    Dolgov, A D; Rudenko, A S

    2016-01-01

    We consider thick domain walls in a de Sitter universe following paper by Basu and Vilenkin. However, we are interested not only in stationary solutions found therein, but also investigate the general case of domain wall evolution with time. When the wall thickness parameter, $\\delta_0$, is smaller than $H^{-1}/\\sqrt{2}$, where $H$ is the Hubble parameter in de Sitter space-time, then the stationary solutions exist, and initial field configurations tend with time to the stationary ones. However, there are no stationary solutions for $\\delta_0 \\geq H^{-1}/\\sqrt{2}$. We have calculated numerically the rate of the wall expansion in this case and have found that the width of the wall grows exponentially fast for $\\delta_0 \\gg H^{-1}$. An explanation for the critical value $\\delta_{0c} = H^{-1}/\\sqrt{2}$ is also proposed.

  18. Calculation of arterial wall temperature in atherosclerotic arteries: effect of pulsatile flow, arterial geometry, and plaque structure

    Directory of Open Access Journals (Sweden)

    Kim Taehong

    2007-03-01

    Full Text Available Abstract Background This paper presents calculations of the temperature distribution in an atherosclerotic plaque experiencing an inflammatory process; it analyzes the presence of hot spots in the plaque region and their relationship to blood flow, arterial geometry, and inflammatory cell distribution. Determination of the plaque temperature has become an important topic because plaques showing a temperature inhomogeneity have a higher likelihood of rupture. As a result, monitoring plaque temperature and knowing the factors affecting it can help in the prevention of sudden rupture. Methods The transient temperature profile in inflamed atherosclerotic plaques is calculated by solving an energy equation and the Navier-Stokes equations in 2D idealized arterial models of a bending artery and an arterial bifurcation. For obtaining the numerical solution, the commercial package COMSOL 3.2 was used. The calculations correspond to a parametric study where arterial type and size, as well as plaque geometry and composition, are varied. These calculations are used to analyze the contribution of different factors affecting arterial wall temperature measurements. The main factors considered are the metabolic heat production of inflammatory cells, atherosclerotic plaque length lp, inflammatory cell layer length lmp, and inflammatory cell layer thickness dmp. Results The calculations indicate that the best location to perform the temperature measurement is at the back region of the plaque (0.5 ≤ l/lp ≤ 0.7. The location of the maximum temperature, or hot spot, at the plaque surface can move during the cardiac cycle depending on the arterial geometry and is a direct result of the blood flow pattern. For the bending artery, the hot spot moves 0.6 millimeters along the longitudinal direction; for the arterial bifurcation, the hot spot is concentrated at a single location due to the flow recirculation observed at both ends of the plaque. Focusing on the

  19. Development of the boiler tube wall thickness ultrasonic detector

    International Nuclear Information System (INIS)

    Wall thickness of fossil fuel firing power boiler tubes are measured by ultrasonic test at regular intervals as part of in-service inspections. The measuring tubes are located high up on the boiler and at restricted sites, and many man-hours are required for preparatory of boiler tube wall thickness scale removal. To improve the efficiency and reliability of boiler tube wall thickness measurements, a system was developed for measuring the tube wall thickness by ultrasonic test from inside the tube. The primary features of this system are: 1) polishing on the outersurface of boiler tubes is not necessary because measurements are made from inside. (Reduction of man-hours), 2) measurements in limited places where manual measurement is difficult or impossible is made possible because automatic measurement from inside the tube is made by an ultrasonic probe introduced into the tube from the inspection hole of the header. (Improvement of reliability), and 3) the tube wall thickness is measured by a submerged ultrasonic rotary probe at an accuracy of ±0.1 mm along the full length. (Improvement of reliability)

  20. Occlusion-free Blood Flow Animation with Wall Thickness Visualization.

    Science.gov (United States)

    Lawonn, Kai; Glaßer, Sylvia; Vilanova, Anna; Preim, Bernhard; Isenberg, Tobias

    2016-01-01

    We present the first visualization tool that combines pathlines from blood flow and wall thickness information. Our method uses illustrative techniques to provide occlusion-free visualization of the flow. We thus offer medical researchers an effective visual analysis tool for aneurysm treatment risk assessment. Such aneurysms bear a high risk of rupture and significant treatment-related risks. Therefore, to get a fully informed decision it is essential to both investigate the vessel morphology and the hemodynamic data. Ongoing research emphasizes the importance of analyzing the wall thickness in risk assessment. Our combination of blood flow visualization and wall thickness representation is a significant improvement for the exploration and analysis of aneurysms. As all presented information is spatially intertwined, occlusion problems occur. We solve these occlusion problems by dynamic cutaway surfaces. We combine this approach with a glyph-based blood flow representation and a visual mapping of wall thickness onto the vessel surface. We developed a GPU-based implementation of our visualizations which facilitates wall thickness analysis through real-time rendering and flexible interactive data exploration mechanisms. We designed our techniques in collaboration with domain experts, and we provide details about the evaluation of the technique and tool. PMID:26529724

  1. Carotid wall stress calculated with continuous intima-media thickness assessment using B-mode ultrasound

    Science.gov (United States)

    Pascaner, A. F.; Craiem, D.; Casciaro, M. E.; Danielo, R.; Graf, S.; Guevara, E.

    2016-04-01

    Cardiovascular risk is normally assessed using clinical risk factors but it can be refined using non-invasive infra-clinical markers. Intima-Media Thickness (IMT) is recognized as an early indicator of cardiovascular disease. Carotid Wall Stress (CWS) can be calculated using arterial pressure and carotid size (diameter and IMT). Generally, IMT is measured during diastole when it reaches its maximum value. However, it changes during the cardiac cycle and a time-dependant waveform can be obtained using B-mode ultrasound images. In this work we calculated CWS considering three different approaches for IMT assessment: (i) constant IMT (standard diastolic value), (ii) estimated IMT from diameter waveform (assuming a constant cross-sectional wall area) and (iii) continuously measured IMT. Our results showed that maximum wall stress depends on the IMT estimation method. Systolic CWS progressively increased using the three approaches (pwall thickness and accurate IMT measures during systole should be encouraged.

  2. The Impact of Intima-media Thickness of Radial Artery on Early Failure of Radiocephalic Arteriovenous Fistula in Hemodialysis Patients

    OpenAIRE

    KIM, YOUNG OK; Choi, Yeong Jin; Kim, Ji Il; Kim, Young Soo; Kim, Byung Soo; Park, Chul Whee; Song, Ho Cheol; Yoon, Sun Ae; Chang, Yoon Sik; Bang, Byung Kee

    2006-01-01

    This study was performed to investigate the impact of intima-media thickness (IMT) of radial artery on early failure of radiocephalic arteriovenous fistula (AVF) in hemodialysis (HD) patients. Ninety uremic patients undergoing radiocephalic AVF operation were included in this study. During the operation, 10-mm long partial arterial walls were removed with elliptical form for microscopic analysis. Specimens were stained with trichrome and examined by a pathologist blinded to the clinical data....

  3. Diabetes Mellitus, Arterial Wall, and Cardiovascular Risk Assessment

    Science.gov (United States)

    Kozakova, Michaela; Palombo, Carlo

    2016-01-01

    Diabetes mellitus is an independent risk factor for atherothrombotic cardiovascular disease. Adults with diabetes are two to four times more likely to develop heart disease or stroke than adults without diabetes. The two major features of diabetes, i.e., hyperglycemia and insulin-resistance, trigger arterial stiffening and increase the susceptibility of the arterial wall to atherosclerosis at any given age. These pathological changes in the arterial wall may provide a functional and structural background for cardiovascular events. The present paper provides a critical overview of the clinical evidence linking diabetes-related metabolic abnormalities to cardiovascular risk, debates the pathophysiologic mechanisms through which insulin resistance and hyperglycemia may affect the arterial wall, and discusses the associations between vascular biomarkers, metabolic abnormalities and cardiovascular events. PMID:26861377

  4. Stability of resistive wall modes with plasma rotation and thick wall in ITER scenario

    Science.gov (United States)

    Zheng, L. J.; Kotschenreuther, M.; Chu, M.; Chance, M.; Turnbull, A.

    2004-11-01

    The rotation effect on resistive wall modes (RWMs) is examined for realistically shaped, high-beta tokamak equilibria, including reactor relevant cases with low mach number M and realistic thick walls. For low M, Stabilization of RWMs arises from unusually thin inertial layers. The investigation employs the newly developed adaptive eigenvalue code (AEGIS: Adaptive EiGenfunction Independent Solution), which describes both low and high n modes and is in good agreement with GATO in the benchmark studies. AEGIS is unique in using adaptive methods to resolve such inertial layers with low mach number rotation. This feature is even more desirable for transport barrier cases. Additionally, ITER and reactors have thick conducting walls ( ˜.5-1 m) which are not well modeled as a thin shell. Such thick walls are considered here, including semi-analytical approximations to account for the toroidally segmented nature of real walls.

  5. Age dependent dynamics of intima-media complex thickness in elderly patients with arterial hypertension

    Directory of Open Access Journals (Sweden)

    Sadjaya L.A.

    2011-09-01

    Full Text Available Aim: To estimate the dynamics of intima-media complex in elderly patients with arterial hypertension. Materials: 179 elderly patients with arterial hypertension were involved in the study. Mean intima-media wall thickness (IMT of common carotid arteries in plaque-free sites and prevalence of plaques were evaluated by B-mode ultrasound investigation (Philips Envisor HD, USA. Results: IMT changing was of nonlinear character, remained stable up to 74 years. Mean rate of the following IMT augmentation was 0.157 mm per year. Frequency of atherosclerotic plaque revealing was significantly increased since the 7th decade. Significant correlation between IMT and systolic, diastolic, mean blood pressure levels or medication spectrum was not revealed. Conclusion: Received data proved significant influence of aging upon IMT enlargement

  6. Digital radiography for automated wall thickness measurement at insulated pipes

    International Nuclear Information System (INIS)

    The digital radiography system AMICA-410 enables the measurement of pipe wall thickness as well as pipe cross section at insulated and non-insulated pipework, and on stream processing and analysis of data with the integrated software. The hardware and software of the system and its performance are explained in the context of the scanning tasks. (orig./CB)

  7. Assessment of carotid diameter and wall thickness in ultrasound images using active contours improved by a multiresolution technique

    Science.gov (United States)

    Gutierrez, Marco A.; Pilon, Paulo E.; Lage, Silvia G.; Kopel, Liliane; Carvalho, Ricardo T.; Furuie, Sergio S.

    2002-04-01

    Carotid vessel ultrasound imaging is a reliable non-invasive technique to measure the arterial morphology. Vessel diameter, intima-media thickness (IMT) of the far wall and plaque presence can be reliably determined using B-mode ultrasound. In this paper we describe a semi-automatic approach to measure artery diameter and IMT based on an active contour technique improved by a multiresolution analysis. The operator selects a region-of-interest (ROI) in a series of carotid images obtained from B-mode ultrasound. This set of images is convolved with the corresponding partial derivatives of the Gaussian filter. The filter response is used to compute a 2D gradient magnitude image in order to refine the vessel's boundaries. Using an active contour technique the vessel's border is determined automatically. The near wall media-adventitia (NWMA), far wall media-adventitia (FWMA) and far wall lumen-intima (FWLI) borders are obtained by a least-square fitting of the active contours result. The distance between NWMA and FWLI (vessel diameter) and between FWLI and FWMA (far wall intima-media thickness) are obtained for all images and the mean value is computed during systole and diastole. The proposed method is a reliable and reproducible way of assessing the vessel diameter and far wall intima-media thickness of the carotid artery.

  8. Acceptance limits for steam generator tube loss of wall thickness

    International Nuclear Information System (INIS)

    This report presents a review of acceptance limits for steam generator tube loss of wall thickness for Bruce B. The limits are directed at loss of wall resulting from fretting wear experienced at U-bend supports. The report also reviews experience in other countries regarding occurrence of fretting wear and other flow-induced vibration problems, such as fatigue and corrosion fatigue. It reviews contemplated remedial fixes for the Bruce B fretting problems, and develops conclusions and recommendations regarding the remedial approaches and supporting inspection plans. (Author) 93 refs., 9 figs

  9. Wall thickness gauging device for moved glass tubes

    International Nuclear Information System (INIS)

    The invention has been aimed at a wall thickness gauging device for moved glass tubes on the basis of isotopic measuring techniques and can be applied to the glass tube production. Faulty measurements due to alterations of the glass tube position during the manufacturing process can be avoided. An auxiliary attachment has been established which makes it possible to detect position errors of the glass tube with regard to the measuring equipment and to carry out a correction of the measuring equipment position. By means of opto-electronic measuring equipment the position of tube edges is determined and in the case of a deviation from the prescribed position due to glass tube movement the wall thickness gauging device will automatically follow up the tube

  10. Multilayer injection moulding of thick-walled optical plastics parts

    Science.gov (United States)

    Hopmann, Ch.; Neuss, A.; Weber, M.; Walach, P.

    2014-05-01

    Optical components are often thick-walled. The cycle time of precise polymer optics with a wall thickness of more than 20 mm exceeds several minutes. The multilayer injection moulding or compression moulding lowers the cycle time and increases the quality of the moulded parts. For the production of multilayer moulded lenses the mould design plays an important role. An innovative mould concept is presented with the possiblity to produce double or triple layer lenses. To ensure the quality and the endurance of multilayer moulded optical components in their applications, the cohesion in the interface is important. Tensile shear tests show the ability of multilayer moulded parts with high cohesion values for optical applications.

  11. Modeling operations back extrusion billets thick-walled anisotropic

    OpenAIRE

    ПЛАТОНОВ В.И.; Яковлев, С. С.

    2014-01-01

    The mathematical model is an inverse extrusion thick-walled tube blanks of material having anisotropic mechanical properties cylindrical. Relations are given to assess the kinematics of course materials la, stress and strain states, power operation modes reverse extrusion. The results of theoretical investigations of power modes. You are the manifest effects of process parameters on the power mode of operation isothermal reverse extrusion billets of high anisotropic materials in the short-ter...

  12. Relaxation of Thick-Walled Cylinders and Spheres

    DEFF Research Database (Denmark)

    Saabye Ottosen, N.

    1982-01-01

    Using the nonlinear creep law proposed by Soderberg, (1936) closed-form solutions are derived for the relaxation of incompressible thick-walled spheres and cylinders in plane strain. These solutions involve series expressions which, however, converge very quickly. By simply ignoring these series...... expressions, extremely simple approximate solutions are obtained. Despite their simplicity these approximations possess an accuracy that is superior to approximations currently in use. Finally, several physical aspects related to the relaxation of cylinders and spheres are discussed...

  13. Serum Carotenoids Reduce Progression of Early Atherosclerosis in the Carotid Artery Wall among Eastern Finnish Men

    OpenAIRE

    Jouni Karppi; Sudhir Kurl; Kimmo Ronkainen; Jussi Kauhanen; Laukkanen, Jari A.

    2013-01-01

    BACKGROUND: Several previous epidemiologic studies have shown that high blood levels of carotenoids may be protective against early atherosclerosis, but results have been inconsistent. We assessed the association between atherosclerotic progression, measured by intima-media thickness of the common carotid artery wall, and serum levels of carotenoids. METHODS: We studied the effect of carotenoids on progression of early atherosclerosis in a population-based study. The association between conce...

  14. Arterial Thickness and Immunometabolism: The Mediating role of Chronic Exercise.

    Science.gov (United States)

    Antunes, B M M; Cayres, S U; Lira, F S; Fernandes, R A

    2016-01-01

    Metabolic alterations and cardiovascular diseases, such as atherosclerosis, are associated with lifestyle modifications, particularly the increase of physical inactivity and poor eating habits, which contribute to one of the main causes of death in modern times. Cardiovascular diseases are positively correlated with several illnesses, such as obesity, hypertension and dyslipidemia, and these disorders are known to contribute to changes in immune cells, cytokines and metabolism. Atherosclerosis is a chronic inflammatory disease characterized by the formation of lipid plaques and fibrous tissue (atheroma) in the artery walls and this process is related to the oxidation of LDL-c (low density lipoprotein) and the formation of a particle, termed LDLox, which can generate toxic injury to the vessel wall. In this atherogenic process there is an inflammatory response generated by the injury in the vascular endothelium, which in itself is able to express and secrete a variety of molecules, such as myeloid colony-stimulating factors (M-CSF), monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor alpha (TNF-α), that act as activators of the immune system. Therefore, the main purpose of this review is to highlight the immuno-metabolic alterations involving the thickening and stiffness of arteries observed in atherosclerosis, and how chronic exercise can act as an anti-inflammatory and anti-atherogenic approach. PMID:26818486

  15. Wall Shear Stress Distribution in Patient Specific Coronary Artery Bifurcation

    Directory of Open Access Journals (Sweden)

    Vahab Dehlaghi

    2010-01-01

    Full Text Available Problem statement: Atherogenesis is affected by hemodynamic parameters, such as wall shear stress and wall shear stress spatial gradient. These parameters are largely dependent on the geometry of arterial tree. Arterial bifurcations contain significant flow disturbances. Approach: The effects of branch angle and vessel diameter ratio at the bifurcations on the wall shear stress distribution in the coronary arterial tree based on CT images were studied. CT images were digitally processed to extract geometrical contours representing the coronary vessel walls. The lumen of the coronary arteries of the patients was segmented using the open source software package (VMTK. The resulting lumens of coronary arteries were fed into a commercial mesh generator (GAMBIT, Fluent Inc. to generate a volume that was filled with tetrahedral elements. The FIDAP software (Fluent Corp. was used to carry out the simulation by solving Navier-Stokes equations. The FIELDVIEW software (Version 10.0, Intelligent Light, Lyndhurst, NJ was used for the visualization of flow patterns and the quantification of wall shear stress. Post processing was done with VMTK and MATLAB. A parabolic velocity profile was prescribed at the inlets and outlets, except for 1. Stress free outlet was assigned to the remaining outlet. Results: The results show that for angle lower than 90°, low shear stress regions are observed at the non-flow divider and the apex. For angle larger than 90°, low shear stress regions only at the non-flow divider. By increasing of diameter of side branch ratio, low shear stress regions in the side branch appear at the non-flow divider. Conclusion: It is concluded that not only angle and diameter are important, but also the overall 3D shape of the artery. More research is required to further quantify the effects angle and diameter on shear stress patterns in coronaries.

  16. Evaluation of Subfoveal Choroidal Thickness in Internal Carotid Artery Stenosis

    Science.gov (United States)

    Akçay, Betül İlkay Sezgin; Kardeş, Esra; Maçin, Sultan; Ünlü, Cihan; Özgürhan, Engin Bilge; Maçin, Aydın; Bozkurt, Tahir Kansu; Ergin, Ahmet; Surmeli, Reyhan

    2016-01-01

    Purpose. To evaluate the relationship between internal carotid artery (ICA) stenosis and subfoveal choroidal thickness (SFCT) in the elderly population. Methods. A total of 42 eyes of 21 patients with more than 70% ICA stenosis (Group 1) on one side and less than 70% stenosis (Group 2) on the other side were recruited for this study. ICA stenosis was diagnosed using both the B-mode and Doppler ultrasound. The two groups were compared in terms of the percentage of stenosis, SFCT measurements, intraocular pressure, ocular perfusion pressure, refractive error, and peak systolic velocity. Eyes were examined with the RTVue-100 OCT device by the EDI-OCT technique. Results. The mean age of the patients was 71.9 ± 10.8 years. The mean percentage of ICA stenosis was 74 ± 4.9% in Group 1 and 47.5 ± 7.7% in Group 2. The mean SFCT was 231.9 ± 44.6 μm in Group 1 and 216.2 ± 46.8 μm in Group 2, which was significantly lower (P = 0.028). A statistically significant positive correlation was found between the percentage of internal carotid artery stenosis and SFCT (r = 0896, P = 0.001). Conclusions. Compensatory SFCT increase can be seen in ipsilateral internal carotid artery stenosis greater than 70%. PMID:26989500

  17. Carotid Artery Segmentation in Ultrasound Images and Measurement of Intima-Media Thickness

    Directory of Open Access Journals (Sweden)

    Vaishali Naik

    2013-01-01

    Full Text Available Background. The segmentation of the common carotid artery (CCA wall is imperative for the determination of the intima-media thickness (IMT on B-mode ultrasound (US images. The IMT is considered an important indicator in the evaluation of the risk for the development of atherosclerosis. In this paper, authors have discussed the relevance of measurements in clinical practices and the challenges that one has to face while approaching the segmentation of carotid artery on ultrasound images. The paper presents an overall review of commonly used methods for the CCA segmentation and IMT measurement along with the different performance metrics that have been proposed and used for performance validation. Summary and future directions are given in the conclusion.

  18. A new high-resolution spectral approach to noninvasively evaluate wall deformations in arteries.

    Science.gov (United States)

    Bazan, Ivonne; Negreira, Carlos; Ramos, Antonio; Brum, Javier; Ramirez, Alfredo

    2014-01-01

    By locally measuring changes on arterial wall thickness as a function of pressure, the related Young modulus can be evaluated. This physical magnitude has shown to be an important predictive factor for cardiovascular diseases. For evaluating those changes, imaging segmentation or time correlations of ultrasonic echoes, coming from wall interfaces, are usually employed. In this paper, an alternative low-cost technique is proposed to locally evaluate variations on arterial walls, which are dynamically measured with an improved high-resolution calculation of power spectral densities in echo-traces of the wall interfaces, by using a parametric autoregressive processing. Certain wall deformations are finely detected by evaluating the echoes overtones peaks with power spectral estimations that implement Burg and Yule Walker algorithms. Results of this spectral approach are compared with a classical cross-correlation operator, in a tube phantom and "in vitro" carotid tissue. A circulating loop, mimicking heart periods and blood pressure changes, is employed to dynamically inspect each sample with a broadband ultrasonic probe, acquiring multiple A-Scans which are windowed to isolate echo-traces packets coming from distinct walls. Then the new technique and cross-correlation operator are applied to evaluate changing parietal deformations from the detection of displacements registered on the wall faces under periodic regime. PMID:24688596

  19. A New High-Resolution Spectral Approach to Noninvasively Evaluate Wall Deformations in Arteries

    Directory of Open Access Journals (Sweden)

    Ivonne Bazan

    2014-01-01

    Full Text Available By locally measuring changes on arterial wall thickness as a function of pressure, the related Young modulus can be evaluated. This physical magnitude has shown to be an important predictive factor for cardiovascular diseases. For evaluating those changes, imaging segmentation or time correlations of ultrasonic echoes, coming from wall interfaces, are usually employed. In this paper, an alternative low-cost technique is proposed to locally evaluate variations on arterial walls, which are dynamically measured with an improved high-resolution calculation of power spectral densities in echo-traces of the wall interfaces, by using a parametric autoregressive processing. Certain wall deformations are finely detected by evaluating the echoes overtones peaks with power spectral estimations that implement Burg and Yule Walker algorithms. Results of this spectral approach are compared with a classical cross-correlation operator, in a tube phantom and “in vitro” carotid tissue. A circulating loop, mimicking heart periods and blood pressure changes, is employed to dynamically inspect each sample with a broadband ultrasonic probe, acquiring multiple A-Scans which are windowed to isolate echo-traces packets coming from distinct walls. Then the new technique and cross-correlation operator are applied to evaluate changing parietal deformations from the detection of displacements registered on the wall faces under periodic regime.

  20. Failure criterion and loads for thick-walled containers

    International Nuclear Information System (INIS)

    The aim of the work is the calculation of failure loads in thick-walled pipes and containers, which consist of a material, which behaves elastically/plastically according to the von Mises flow criterion. The stress/strain ratio of this material in tensile tests is found to be a steady smooth curve, which is linear in the elastic region and has a tendency to become asymptotic for large strains. The model should not be of a purely isotropic nature, but should permit kinetic solidification, in order to be able to simulate the Bauschinger effect found in real materials. Apart from the described non-linearity of the material, in the structures dealt with, one must not forget the geometric non-linearity, particularly as in the load case of hydrostatic internal pressure, which always acts at right angles to the wall being deformed, the load is not conservative. The problem is tackled with the method of finite elements. (orig./HP)

  1. Thick-wall effects on the rotational stabilization of resistive wall modes in tokamaks

    International Nuclear Information System (INIS)

    This paper is devoted to studying the combined effect of mode rotation and energy dissipation in the resistive wall on plasma stability. The problem is analysed on the basis of the energy approach complementing the standard methods of the traditional MHD theory of plasma stability. The key element that makes our model different from this theory and commonly used thin-wall approaches to the stability analysis of resistive wall modes (RWMs) is the incorporation of the skin effect. In the ideal MHD theory of plasma stability, the skin depth is, formally, zero. In contrast, the conventional thin-wall theory of RWM stability assumes a skin depth much larger than the wall thickness. The presented model considers the intermediate case with a finite skin depth compared with the wall thickness. This covers the modes in between the typical RWMs and the ideal MHD modes when wall resistivity still affects the mode dynamics. It is shown that, in this region, the growth rate of the locked modes must be substantially larger than that calculated in the thin-wall models. On the other hand, the fast RWMs can be completely stabilized by mode rotation above some critical level. Qualitatively, this corresponds to the rotational stabilization observed in the DIII-D tokamak and allowing the plasma operation above the no-wall stability limit (Strait et al 2003 Nucl. Fusion 43 430). This is the main result of this study, which is completely analytical with all dependences explicitly shown. In particular, the dispersion relations for the fast RWMs and the critical frequency of mode rotation necessary for rotational stabilization are expressed through quantities that depend on the plasma parameters or can be experimentally found by magnetic measurements outside the plasma. (paper)

  2. 股动脉僵硬度、内中膜厚度和踝臂指数在2 型糖尿病患者下肢血管评价中的价值%Evaluation of peripheral vascular disease with femoral artery wall thickness,stiffness and ankle brachium index in type 2 diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    聂芳; 陈慧; 陈斌娟; 车岩; 鲁虹霞; 胥萍

    2009-01-01

    目的 探讨股动脉僵硬度、内中膜厚度和踝臂指数(ABI)评价2型糖尿病患者外周血管疾病(PVD)的价值.方法 151例2型糖尿病患者以有无下肢临床症状分为PVD症状组和无PVD症状组;以ABI值分为ABI异常组(<0.9)和ABI正常组(≥0.9).二维超声测量股动脉内中膜厚度(FA-IMT),彩色流速流量定量技术测量股动脉收缩期及舒张期的内径(Ds及Dd),计算股动脉僵硬度(FA-β).比较FA-IMT和FA-β的组间差异;探讨FA-IMT与FA-β的相关性;多元回归分析FA-IMT、FA-β与PVD症状及ABI减低的相关性.结果 与无PVD症状组比较,PVD症状组FA-IMT、FA-β增高(P<0.01);与ABI正常组相比,ABI异常组FA-IMT、FA-β增高(P<0.01).在PVD症状组中,FA-IMT与FA-β无相关性.多元回归分析显示FA-β与PVD症状密切相关;FA-IMT与ABI减低密切相关.结论 动脉僵硬度在2型糖尿病患者下肢血管疾病评价中有重要作用.%Objective To evaluate the effects of femoral artery wall thickness, stillness and ankle brachium index(ABI) on clinical manifestation of peripheral vascular disease(PVD) in type 2 diabetes mellitus. Methods According to the presence of lower limb and reduced ABI (ABI<0.9), 151 patients with type 2 diabetes were divided into group of patients with and without PVD symptoms, and group of patients with and without reduced ABI. Intima-media thickness of femoral artery (FA-IMT) and stiffness of femoral artery (FA-β) were measured by ultrasound. FA-IMA and FA-β of femoral arteries were compared between group of patients with and without PVD symptoms as well as between group of patients with and without reduced ABI. Correlation between FA-IMT and FA-β was analyzed. Factors affecting symptoms of lower limb and ABI were evaluated by multiple logistic regression analysis. Results FA-IMT and FA-β in group of PVD symptoms were higher than those in group without PVD symptoms. Similarly, patients with reduced ABI had greater FA-IMT and FA-β than those

  3. Terahertz inline wall thickness monitoring system for plastic pipe extrusion

    Science.gov (United States)

    Hauck, J.; Stich, D.; Heidemeyer, P.; Bastian, M.; Hochrein, T.

    2014-05-01

    Conventional and commercially available inline wall thickness monitoring systems for pipe extrusion are usually based on ultrasonic or x-ray technology. Disadvantages of ultrasonic systems are the usual need of water as a coupling media and the high damping in thick walled or foamed pipes. For x-ray systems special safety requirements have to be taken into account because of the ionizing radiation. The terahertz (THz) technology offers a novel approach to solve these problems. THz waves have many properties which are suitable for the non-destructive testing of plastics. The absorption of electrical isolators is typically very low and the radiation is non-ionizing in comparison to x-rays. Through the electromagnetic origin of the THz waves they can be used for contact free measurements. Foams show a much lower absorption in contrast to acoustic waves. The developed system uses THz pulses which are generated by stimulating photoconductive switches with femtosecond laser pulses. The time of flight of THz pulses can be determined with a resolution in the magnitude of several ten femtoseconds. Hence the thickness of an object like plastic pipes can be determined with a high accuracy by measuring the time delay between two reflections on materials interfaces e.g. at the pipe's inner and outer surface, similar to the ultrasonic technique. Knowing the refractive index of the sample the absolute layer thickness from the transit time difference can be calculated easily. This method in principle also allows the measurement of multilayer systems and the characterization of foamed pipes.

  4. 49 CFR 192.109 - Nominal wall thickness (t) for steel pipe.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Nominal wall thickness (t) for steel pipe. 192.109... TRANSPORTATION OF NATURAL AND OTHER GAS BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Pipe Design § 192.109 Nominal wall thickness (t) for steel pipe. (a) If the nominal wall thickness for steel pipe is not...

  5. An approach for patient-specific multi-domain vascular mesh generation featuring spatially varying wall thickness modeling.

    Science.gov (United States)

    Raut, Samarth S; Liu, Peng; Finol, Ender A

    2015-07-16

    In this work, we present a computationally efficient image-derived volume mesh generation approach for vasculatures that implements spatially varying patient-specific wall thickness with a novel inward extrusion of the wall surface mesh. Multi-domain vascular meshes with arbitrary numbers, locations, and patterns of both iliac bifurcations and thrombi can be obtained without the need to specify features or landmark points as input. In addition, the mesh output is coordinate-frame independent and independent of the image grid resolution with high dimensional accuracy and mesh quality, devoid of errors typically found in off-the-shelf image-based model generation workflows. The absence of deformable template models or Cartesian grid-based methods enables the present approach to be sufficiently robust to handle aneurysmatic geometries with highly irregular shapes, arterial branches nearly parallel to the image plane, and variable wall thickness. The assessment of the methodology was based on i) estimation of the surface reconstruction accuracy, ii) validation of the output mesh using an aneurysm phantom, and iii) benchmarking the volume mesh quality against other frameworks. For the phantom image dataset (pixel size 0.105 mm; slice spacing 0.7 mm; and mean wall thickness 1.401±0.120 mm), the average wall thickness in the mesh was 1.459±0.123 mm. The absolute error in average wall thickness was 0.060±0.036 mm, or about 8.6% of the largest image grid spacing (0.7 mm) and 4.36% of the actual mean wall thickness. Mesh quality metrics and the ability to reproduce regional variations of wall thickness were found superior to similar alternative frameworks. PMID:25976018

  6. Effect of wall thickness of left ventricle on {sup 201}Tl myocardial SPECT images. Myocardial phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Koto, Masanobu; Kawase, Osami [Kobe Univ. (Japan). Hospital; Namura, Hiroyuki; Yamasaki, Katsuhito; Kono, Michio

    1996-07-01

    {sup 201}Tl myocardial SPECT is known for better sensitivity, specificity, and accuracy than planar images in detecting coronary artery disease and diagnosing myocardial viability. SPECT images arc also superior to planar images in diagnostic sensitivity and anatomical orientation. However, as limitation of the spatial resolution of the machine, we often encounter poor SPECT plower image quality in patients with decreased wall thickness. To test the accuracy of SPECT images in patients with marked thinning of the left ventricular wall, as occurs in dilated cardiomyopathy, we performed a experimental study using myocardial phantom with 7 mm wall thickness. Tomographic image of the phantom images were rather heterogeneous, though no artificial defect was located Dilated cardiomyopathy is thought to be characterized by patchy defects in the left ventricle. Careful attention should be given to elucidating myocardial perfusion in patients with a thin left ventricle wall, as there are technical limitations in addition to clinical features. (author)

  7. Cross-Sectional Elasticity Imaging of Carotid Arterial Wall in Short-Axis Plane by Transcutaneous Ultrasound

    Science.gov (United States)

    Nakagawa, Nozomi; Hasegawa, Hideyuki; Kanai, Hiroshi

    2004-05-01

    We have developed the phased tracking method [H. Kanai, M. Sato, Y. Koiwa and N. Chubachi: IEEE Trans. UFFC 43 (1996) 791.] for measuring the minute change in thickness during one heartbeat and the elasticity of the arterial wall with transcutaneous ultrasound. When this method is applied to a plane perpendicular to the axis of the artery (short-axis plane) using a linear-type probe, only an ultrasonic beam which passes through the center of the artery coincides with the direction of the change in thickness. At other beam positions, the wall motion cannot be accurately tracked because the direction of wall expansion slips off the beam. To obtain the cross-sectional image of elasticity in the short-axis plane using transcutaneous ultrasound, in this paper, the directions of ultrasonic beams are designed so that each beam always passes through the center of the artery; thus, they always coincide with the direction of the wall expansion. In basic experiments, the accuracy in elasticity measurement was evaluated using a silicone rubber tube. In in vivo experiments, the minute change in wall thickness was measured along each ultrasonic beam, and the cross-sectional image of elasticity was obtained in the short-axis plane with transcutaneous ultrasound.

  8. Fully automated segmentation and tracking of the intima media thickness in ultrasound video sequences of the common carotid artery

    OpenAIRE

    Ghita, Dana Ilea; Duffy, Caoimhe; Kavanagh, Liam; Stanton, Alice; Whelan, Paul F.

    2013-01-01

    Abstract—The robust identification and measurement of the intima media thickness (IMT) has a high clinical relevance because it represents one of the most precise predictors used in the assessment of potential future cardiovascular events. To facilitate the analysis of arterial wall thickening in serial clinical investigations, in this paper we have developed a novel fully automatic algorithm for the segmentation, measurement, and tracking of the intima media complex (IMC) in B-mode ultrasoun...

  9. Constitutive modelling of an arterial wall supported by microscopic measurements

    Directory of Open Access Journals (Sweden)

    Vychytil J.

    2012-06-01

    Full Text Available An idealized model of an arterial wall is proposed as a two-layer system. Distinct mechanical response of each layer is taken into account considering two types of strain energy functions in the hyperelasticity framework. The outer layer, considered as a fibre-reinforced composite, is modelled using the structural model of Holzapfel. The inner layer, on the other hand, is represented by a two-scale model mimicing smooth muscle tissue. For this model, material parameters such as shape, volume fraction and orientation of smooth muscle cells are determined using the microscopic measurements. The resulting model of an arterial ring is stretched axially and loaded with inner pressure to simulate the mechanical response of a porcine arterial segment during inflation and axial stretching. Good agreement of the model prediction with experimental data is promising for further progress.

  10. A mathematical model for estimating the axial stress of the common carotid artery wall from ultrasound images.

    Science.gov (United States)

    Soleimani, Effat; Mokhtari-Dizaji, Manijhe; Saberi, Hajir; Sharif-Kashani, Shervin

    2016-08-01

    Clarifying the complex interaction between mechanical and biological processes in healthy and diseased conditions requires constitutive models for arterial walls. In this study, a mathematical model for the displacement of the carotid artery wall in the longitudinal direction is defined providing a satisfactory representation of the axial stress applied to the arterial wall. The proposed model was applied to the carotid artery wall motion estimated from ultrasound image sequences of 10 healthy adults, and the axial stress waveform exerted on the artery wall was extracted. Consecutive ultrasonic images (30 frames per second) of the common carotid artery of 10 healthy subjects (age 44 ± 4 year) were recorded and transferred to a personal computer. Longitudinal displacement and acceleration were extracted from ultrasonic image processing using a block-matching algorithm. Furthermore, images were examined using a maximum gradient algorithm and time rate changes of the internal diameter and intima-media thickness were extracted. Finally, axial stress was estimated using an appropriate constitutive equation for thin-walled tubes. Performance of the proposed model was evaluated using goodness of fit between approximated and measured longitudinal displacement statistics. Values of goodness-of-fit statistics indicated high quality of fit for all investigated subjects with the mean adjusted R-square (0.86 ± 0.08) and root mean squared error (0.08 ± 0.04 mm). According to the results of the present study, maximum and minimum axial stresses exerted on the arterial wall are 1.7 ± 0.6 and -1.5 ± 0.5 kPa, respectively. These results reveal the potential of this technique to provide a new method to assess arterial stress from ultrasound images, overcoming the limitations of the finite element and other simulation techniques. PMID:26563198

  11. Gelsolin amyloid angiopathy causes severe disruption of the arterial wall.

    Science.gov (United States)

    Koskelainen, Susanna; Pihlamaa, Tiia; Suominen, Sinikka; Zhao, Fang; Salo, Tuula; Risteli, Juha; Baumann, Marc; Kalimo, Hannu; Kiuru-Enari, Sari

    2016-08-01

    Hereditary gelsolin amyloidosis (HGA) is a dominantly inherited systemic disease reported worldwide. HGA is characterized by ophthalmological, neurological, and dermatological manifestations. AGel amyloid accumulates at basal lamina of epithelial and muscle cells, thus amyloid angiopathy is encountered in nearly every organ. HGA patients have cardiovascular, hemorrhagic, and potentially vascularly induced neurological problems. To clarify pathomechanisms of AGel angiopathy, we performed histological, immunohistochemical, and electron microscopic analyses on facial temporal artery branches from 8 HGA patients and 13 control subjects. We demonstrate major pathological changes in arteries: disruption of the tunica media, disorganization of vascular smooth muscle cells, and accumulation of AGel fibrils in arterial walls, where they associate with the lamina elastica interna, which becomes fragmented and diminished. We also provide evidence of abnormal accumulation and localization of collagen types I and III and an increase of collagen type I degradation product in the tunica media. Vascular smooth muscle cells appear to be morphologically and semi-quantitatively normal, only their basal lamina is often thickened. In conclusion, angiopathy in HGA results in severe disruption of arterial walls, characterized by prominent AGel deposition, collagen derangement and severe elastolysis, and it may be responsible for several, particularly hemorrhagic, disease manifestations in HGA. PMID:27198069

  12. Intima-media Thickness and Arterial Stiffness of Carotid Artery in Korean Patients with Behçet's Disease

    OpenAIRE

    Rhee, Moo-Yong; Chang, Hyun Kyu; Kim, Seong-Kyu

    2007-01-01

    Behçet's disease (BD) is a systemic vasculitis involving diverse sizes of arteries and veins. We performed this study to evaluate the vascular changes by assessment of the arterial stiffness and intima-media thickness (IMT) of carotid artery in Korean patients with BD. Forty-one patients with BD and age-, and sex-matched 53 healthy subjects were recruited in this study. Carotid arterial stiffness and IMT were assessed by using high-resolution B-mode ultrasonography. Arterial stiffness paramet...

  13. Measurement of wall thickness with electrodynamic test heads

    International Nuclear Information System (INIS)

    Starting from the boundary conditions fixed by the physical properties of the electromagnetic/acoustic conversion and the operating limits which result from these for the sensors used, the use of electro-dynamic ultrasonic transducers for measuring wall thickness and double checks in plants for automatic production inspection and production control is shown. The sensor itself is the heart of a test system, but only the equipment and plant concepts surrounding the sensor make economic solution of the test problem possible. The quality of the signals which are supplied by a sensor, determines the quality of a test system. This can only be achieved by optimising all parts of a complex automatic test rig, such as the test head, mechanics, electronics and evaluation for the test problem concerned. (orig./HP)

  14. The logic behind thick, liquid-walled, fusion concepts

    International Nuclear Information System (INIS)

    It may be possible to surround the region where fusion reactions are taking place with a neutronically thick liquid blanket which has penetrations that allow only a few tenths of a percent of the neutrons to leak out. Even these neutrons can be attenuated by adding an accurately placed liquid or solid near the target to shadow-shield the beam ports from line-of-sight neutrons. The logic of such designs is discussed and their evolution is described with examples applied to both magnetic and inertial fusion (HYLIFE-II).These designs with liquid protection are self-healing when exposed to pulsed loading, and have a number of advantages over the usual designs with solid first walls. For example, the liquid-protected solid components will last the life of the plant, and therefore the capacity factor is estimated to be approximately 10% higher than for the non-liquid-walled blankets, because no blanket replacement shutdowns are required. The component replacement, operations, and maintenance costs might be half the usual value because no blanket change-out costs or accompanying facilities are required. These combined savings might lower the cost of electricity by 20%.Nuclear-grade construction should not be needed, largely because the liquid attenuates neutrons and results in less activation of materials. Upon decommissioning, the reactor materials should qualify for disposal by shallow burial even when constructed of ordinary 304 stainless steel. The need for a high-intensity 14-MeV neutron test facility to develop first-wall materials is avoided or greatly reduced, saving billions of development dollars. Flowing molten Li, the molten salt Flibe (Li2BeF4), and molten Li17Pb83 have been considered. An advantage of molten salt is that it will not burn and has a low tritium solubility and therefore low tritium inventory. (orig.)

  15. The logic behind thick liquid-walled fusion concepts

    International Nuclear Information System (INIS)

    It may be possible to surround the region where fusion reactions are taking place with an neutronically thick liquid blanket which has penetrations that allow only a few tenths of a percent of the neutrons to leak out. This paper will discuss the logic of such designs and describe their evolution with examples applied to both magnetic and inertial fusion (HYLIFE-II). Theses designs are robust to pulsed loading and have a number of advantages over the usual designs with solid first walls. For example, solid components will last the life-of-the-plant, and therefore the capacity factor is expected to be 10% or so higher than for the non-liquid walled blankets, because no blanket replacement shutdowns are required. The component replacement, operations, and maintenance costs might be half the usual value because no blanket change-out costs or accommodating facilities are required. These savings might lower the cost of electricity by 20%. The components might not have to be of nuclear-grade construction, partly because the liquid attenuates neutrons and results in less activation of materials. Upon decommissioning, the reactor materials might qualify for disposal by shallow burial even when constructed of ordinary 304 stainless steel. The need for a high-intensity 14-MeV neutron test facility to develop first-wall materials is greatly reduced. Flowing molten Li, molten salt (Li2BeF4, called Flibe), and molten Li17Pb83 have been considered. An advantage of molten salt is that it will not burn and has a low tritium solubility and a low tritium inventory, but it has 300 MCi of 2-hr half-life 18F

  16. Comparative measurement of silicon and major elements (P,S,Cl,K,Ca) in arterial walls using macro and microbeam analysis

    International Nuclear Information System (INIS)

    There are few techniques available for the measurement of silicon at trace levels in biological materials. PIXE and prompt nuclear reaction analysis were used to locate and measure silicon and major elements in arterial walls. Macrobeam analysis, carried out by the Van de Graaff accelerator at CENBG, enabled measurement of mean tissue levels. Microbeam analysis, using the nuclear microprobe at Karlsruhe, yielded the distribution of these elements through the thickness of the arterial wall. The microanalyses were performed on arterial walls from healthy rabbits and the macrobeam study was carried out on the same samples and also on human aorta specimens

  17. Wall morphology, blood flow and wall shear stress: MR findings in patients with peripheral artery disease

    Energy Technology Data Exchange (ETDEWEB)

    Galizia, Mauricio S.; Barker, Alex; Collins, Jeremy; Carr, James [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Liao, Yihua [Northwestern University' s Feinberg School of Medicine, Department of Preventive Medicine, Chicago, IL (United States); McDermott, Mary M. [Northwestern University' s Feinberg School of Medicine, Department of Preventive Medicine, Chicago, IL (United States); Northwestern University' s Feinberg School of Medicine, Department of Medicine, Chicago, IL (United States); Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Northwestern University, Department Biomedical Engineering, McCormick School of Engineering, Chicago, IL (United States)

    2014-04-15

    To investigate the influence of atherosclerotic plaques on femoral haemodynamics assessed by two-dimensional (2D) phase-contrast (PC) magnetic resonance imaging (MRI) with three-directional velocity encoding. During 1 year, patients with peripheral artery disease and an ankle brachial index <1.00 were enrolled. After institutional review board approval and written informed consent, 44 patients (age, 70 ± 12 years) underwent common femoral artery MRI. Patients with contra-indications for MRI were excluded. Sequences included 2D time-of-flight, proton-density, T1-weighted and T2-weighted MRI. Electrocardiogram (ECG)-gated 2D PC-MRI with 3D velocity encoding was acquired. A radiologist classified images in five categories. Blood flow, velocity and wall shear stress (WSS) along the vessel circumference were quantified from the PC-MRI data. The acquired images were of good quality for interpretation. There were no image quality problems related to poor ECG-gating or slice positioning. Velocities, oscillatory shear stress and total flow were similar between patients with normal arteries and wall thickening/plaque. Patients with plaques demonstrated regionally increased peak systolic WSS and enhanced WSS eccentricity. Combined multi-contrast morphological imaging of the peripheral arterial wall with PC-MRI with three-directional velocity encoding is a feasible technique. Further study is needed to determine whether flow is an appropriate marker for altered endothelial cell function, vascular remodelling and plaque progression. (orig.)

  18. Wall morphology, blood flow and wall shear stress: MR findings in patients with peripheral artery disease

    International Nuclear Information System (INIS)

    To investigate the influence of atherosclerotic plaques on femoral haemodynamics assessed by two-dimensional (2D) phase-contrast (PC) magnetic resonance imaging (MRI) with three-directional velocity encoding. During 1 year, patients with peripheral artery disease and an ankle brachial index <1.00 were enrolled. After institutional review board approval and written informed consent, 44 patients (age, 70 ± 12 years) underwent common femoral artery MRI. Patients with contra-indications for MRI were excluded. Sequences included 2D time-of-flight, proton-density, T1-weighted and T2-weighted MRI. Electrocardiogram (ECG)-gated 2D PC-MRI with 3D velocity encoding was acquired. A radiologist classified images in five categories. Blood flow, velocity and wall shear stress (WSS) along the vessel circumference were quantified from the PC-MRI data. The acquired images were of good quality for interpretation. There were no image quality problems related to poor ECG-gating or slice positioning. Velocities, oscillatory shear stress and total flow were similar between patients with normal arteries and wall thickening/plaque. Patients with plaques demonstrated regionally increased peak systolic WSS and enhanced WSS eccentricity. Combined multi-contrast morphological imaging of the peripheral arterial wall with PC-MRI with three-directional velocity encoding is a feasible technique. Further study is needed to determine whether flow is an appropriate marker for altered endothelial cell function, vascular remodelling and plaque progression. (orig.)

  19. Relaxed incremental variational approach for the modeling of damage-induced stress hysteresis in arterial walls.

    Science.gov (United States)

    Schmidt, Thomas; Balzani, Daniel

    2016-05-01

    In this paper, a three-dimensional relaxed incremental variational damage model is proposed, which enables the description of complex softening hysteresis as observed in supra-physiologically loaded arterial tissues, and which thereby avoids a loss of convexity of the underlying formulation. The proposed model extends the relaxed formulation of Balzani and Ortiz [2012. Relaxed incremental variational formulation for damage at large strains with application to fiber-reinforced materials and materials with truss-like microstructures. Int. J. Numer. Methods Eng. 92, 551-570], such that the typical stress-hysteresis observed in arterial tissues under cyclic loading can be described. This is mainly achieved by constructing a modified one-dimensional model accounting for cyclic loading in the individual fiber direction and numerically homogenizing the response taking into account a fiber orientation distribution function. A new solution strategy for the identification of the convexified stress potential is proposed based on an evolutionary algorithm which leads to an improved robustness compared to solely Newton-based optimization schemes. In order to enable an efficient adjustment of the new model to experimentally observed softening hysteresis, an adjustment scheme using a surrogate model is proposed. Therewith, the relaxed formulation is adjusted to experimental data in the supra-physiological domain of the media and adventitia of a human carotid artery. The performance of the model is then demonstrated in a finite element example of an overstretched artery. Although here three-dimensional thick-walled atherosclerotic arteries are considered, it is emphasized that the formulation can also directly be applied to thin-walled simulations of arteries using shell elements or other fiber-reinforced biomembranes. PMID:26341795

  20. Finite element limit loads for non-idealized through-wall cracks in thick-walled pipe

    International Nuclear Information System (INIS)

    Highlights: • The lower bound bulging factor of thin-walled pipe can be used for thick-walled pipe. • The limit loads are proposed for thick-walled, transition through-wall cracked pipe. • The correction factors are proposed for estimating limit loads of transition cracks. • The limit loads of short transition cracks are similar to those of idealized cracks. - Abstract: The present paper provides plastic limit loads for non-idealized through-wall cracks in thick-walled pipe. These solutions are based on detailed 3-dimensional finite element (FE) analyses which can be used for structural integrity assessment of nuclear piping. To cover a practical range of interest, the geometric variables and loading conditions affecting the plastic limit loads of thick-walled pipe with non-idealized through-wall cracks were systematically varied. In terms of crack orientation, both circumferential and axial through-wall cracks were considered. As for loading conditions, axial tension, global bending, and internal pressure were considered for circumferential cracks, whereas only internal pressure was considered for axial cracks. Furthermore, the values of geometric factor representing shape characteristics of non-idealized through-wall cracks were also systematically varied. In order to provide confidence in the present FE analyses results, plastic limit loads of un-cracked, thick-walled pipe resulting from the present FE analyses were compared with the theoretical solutions. Finally, correction factors to the idealized through-wall crack solutions were developed to determine the plastic limit loads of non-idealized through-wall cracks in thick-walled pipe

  1. Coronary atherosclerosis burden is not advanced in patients with β-thalassemia despite premature extracardiac atherosclerosis: a coronary artery calcium score and carotid intima-media thickness study

    OpenAIRE

    Hahalis, George; Zacharioglou, Evangelia; Xanthopoulou, Ioanna; Koniari, Ioanna; Kalogeropoulou, Chistina; Tsota, Irene; Rigopoulou, Aspasia; Diamantopoulos, Athanasios; Gkizas, Vasilios; Davlouros, Periklis; Akinosoglou, Karolina; Leopoulou, Marianna; Gogos, Charalampos; Alexopoulos, Dimitrios

    2016-01-01

    Background Thalassemic patients demonstrate an increased rate of extracardiac vascular complications and increased carotid wall intima-media thickness (cIMT), but very low prevalence of coronary artery disease (CAD). We investigated the atheroma burden by assessing the coronary artery calcium (CAC) and cIMT in these patients. Methods We examined 37 patients with β-thalassemia and 150 healthy control volunteers with multi-detector computer tomography (CT) and ultrasonography to determine CAC s...

  2. Limit load analysis of thick-walled concrete structures

    International Nuclear Information System (INIS)

    The paper illustrates the interaction of constitutive modeling and finite element solution techniques for limit load prediction of concrete structures. On the constitutive side, an engineering model of concrete fracture is developed in which the Mohr-Coulomb criterion is augmented by tension cut-off to describe incipient failure. Upon intersection with the stress path the failure surface collapses for brittle behaviour according to one of three softening rules, no-tension, no-cohesion, and no-friction. The stress transfer accompanying the energy dissipation during local failure is modelled by several fracture rules which are examined with regard to ultimate load prediction. On the numerical side the effect of finite element idealization is studied first as far as ultimate load convergence is concerned. Subsequently, incremental tangential and initial load techniques are compared together with the effect of step size. Limit load analyses of a thick-walled concrete ring and a lined concrete reactor closure conclude the paper with examples from practical engineering. (orig.)

  3. Methodology to calculate wall thickness in metallic pipes

    International Nuclear Information System (INIS)

    The principal objective in the developing of the activities of industrial type is to carry out a efficient and productive task: that implies necessarily to know the best working conditions of the equipment and installations to be concerned. The applications of the radioisotope techniques have a long time as useful tools in several fields of human work. For example, in the Petroleos Mexicanos petrochemical complexes, by safety reasons and for to avoid until maximum the losses, it must be know with a high possible precision the operation regimes of the lines of tubes that they conduce the hydrocarbons, with the purpose to know when they should be replaced the defective or wasted pieces. In the Mexican Petroleum Institute is carrying out a work that it has by objective to develop a methodology bases in the use of radioisotopes that permits to determine the average thickness of the metallic tubes wall, that they have thermic insulator, with a precision of ±0.127 mm (±5 thousandth inch). The method is based in the radiation use emitted by Cs-137 sources. In this work it is described the methodology development so as the principal results obtained. (Author)

  4. Ultrasonic Measurement of Transient Change in Stress-Strain Property of Radial Arterial Wall Caused by Endothelium-Dependent Vasodilation

    Science.gov (United States)

    Ikeshita, Kazuki; Hasegawa, Hideyuki; Kanai, Hiroshi

    2008-05-01

    The endothelial dysfunction is considered to be an initial step of atherosclerosis. Additionally, it was reported that the smooth muscle, which constructs the media of the artery, changes its characteristics owing to atherosclerosis. Therefore, it is essential to develop a method for assessing the regional endothelial function and mechanical property of the arterial wall. There is a conventional technique of measuring the transient change in the diameter of the brachial artery caused by flow-mediated dilation (FMD) after the release of avascularization. For more sensitive and regional evaluation, we developed a method of measuring the change in the elasticity of the radial artery due to FMD. In this study, the transient change in the mechanical property of the arterial wall was further revealed by measuring the stress-strain relationship during each heartbeat. The minute change in the thickness (strain) of the radial arterial wall during a cardiac cycle was measured by the phased tracking method, together with the waveform of blood pressure which was continuously measured with a sphygmometer at the radial artery. The transient change in stress-strain relationship during a cardiac cycle was obtained from the measured changes in wall thickness and blood pressure to show the transient change in instantaneous viscoelasticity. From the in vivo experimental results, the stress-strain relationship shows the hysteresis loop. The slope of the loop decreased owing to FMD, which shows that the elastic modulus decreased, and the increasing area of the loop depends on the ratio of the loss modulus (depends on viscosity) to the elastic modulus when the Voigt model is assumed. These results show a potential of the proposed method for the thorough analysis of the transient change in viscoelasticity due to FMD.

  5. Passive cigarette smoking induces inflammatory injury in human arterial walls

    Institute of Scientific and Technical Information of China (English)

    ZOU Ni; HONG Jiang; DAI Qiu-yan

    2009-01-01

    Background Epidemiological studies have shown that both active and passive cigarette smoking increase the risk of atherosclerosis. But very little is known about the biological processes induced by passive cigarette smoking that contribute to atheresclerosis. We observe the expression of a few of biological and inflammatory markers in human arterial walls in vitro which were treated with the second-hand smoke solution (sidestream whole, SSW), and discuss the possible mechanism of inflammatory injury induced by second-hand smoke.Methods The biological markers (platelet endothelial cell adhesion molecule-1, PECAM-1; α-smooth muscle actin, α-SMA; collagen Ⅳ, Col Ⅳ) and inflammatory markers (vascular cell adhesion molecule-1, VCAM-1; monocyte chemoattractant protein-1, MCP-1; interleukin-8, IL-8) of human aortal wall were tested by immunofluorescence staining. The levels of MCP-1 and IL-8 mRNA expression were detected by reverse transcription-polymerase chain reaction (RT-PCR).Results No distinct difference was observed between SSW and the control group on the expression of biological markers as assessed by the light microscope. But the inflammatory markers VCAM-1, MCP-1 and IL-8 on the subendothelial layer and smooth muscle cell layers, which are near the endothelium of arterial wall, were strongly stained in the SSW group compared with the control group. Their fluorescence intensities in the 1:40 SSW group (VCAM-1: 0.35±0.04, MCP-1: 0.34±0.05, IL-8: 0.37±0.05) and the 1:20 SSW group (VCAM-1: 0.40±0.04, MCP-1: 0.52±0.09, IL-8: 0.51±0.07) were significantly stronger than the control group (VCAM-1: 0.12±0.04, MCP-1: 0.06±0.02, IL-8: 0.24±0.03) by semi-quantitative analysis of immunofluorescence (P <0.001 vs control). MCP-1 mRNA expression in the 1:40 SSW (0.15±0.04) and the 1:20 SSW (0.19±0.06) group was significantly higher than in the control group (0.09±0.03) (P <0.05, P <0.01 vs control); IL-8 mRNA expression in the 1:40 SSW (0.64±0.12) and 1

  6. A Probabilistic Approach to Computerized Tracking of Arterial Walls in Ultrasound Image Sequences

    OpenAIRE

    Baris Kanber; Kumar Vids Ramnarine

    2012-01-01

    Tracking of arterial walls in ultrasound image sequences is useful for studying the dynamics of arteries. Manual delineation is prohibitively labour intensive and existing methods of computerized segmentation are limited in terms of applicability and availability. This paper presents a probabilistic approach to the computerized tracking of arterial walls that is effective and easy to implement. In the probabilistic approach, given a point B with a probability Pb of being in an arterial lumen ...

  7. Linear and nonlinear viscoelastic arterial wall models: application on animals

    CERN Document Server

    Ghigo, Arthur; Armentano, Ricardo; Lagrée, Pierre-Yves; Fullana, Jose-Maria

    2016-01-01

    This work deals with the viscoelasticity of the arterial wall and its influence on the pulse waves. We describe the viscoelasticity by a non-linear Kelvin-Voigt model in which the coefficients are fitted using experimental time series of pressure and radius measured on a sheep's arterial network. We obtained a good agreement between the results of the nonlinear Kelvin-Voigt model and the experimental measurements. We found that the viscoelastic relaxation time-defined by the ratio between the viscoelastic coefficient and the Young's modulus-is nearly constant throughout the network. Therefore, as it is well known that smaller arteries are stiffer, the viscoelastic coefficient rises when approaching the peripheral sites to compensate the rise of the Young's modulus, resulting in a higher damping effect. We incorporated the fitted viscoelastic coefficients in a nonlinear 1D fluid model to compute the pulse waves in the network. The damping effect of viscoelasticity on the high frequency waves is clear especiall...

  8. Detection of Arterial Wall Boundaries Using an Echo Model Composed of Multiple Ultrasonic Pulses

    Science.gov (United States)

    Ibrahim, Nabilah; Hasegawa, Hideyuki; Kanai, Hiroshi

    2013-07-01

    The assessment of the intima-media thickness (IMT) of the carotid arterial wall, which is the most frequently used indicator to diagnose atherosclerosis by ultrasound, involves the measurement of the lumen-intima boundary (LIB) and media-adventitia boundary (MAB). In this study, using the mean squared error (MSE) method and by applying the template matching technique, an adaptive model of an ultrasonic echo, which is obtained from an ultrasonic pulse measured with a hydrophone, was fitted with the measured in vivo RF echo to estimate the boundaries of the carotid arterial wall. In the present study, the frequency and phase of the adaptive model were considered to improve the accuracy in the determination of the LIB and MAB. For a 7.5-mm-long short segment of the carotid artery in the longitudinal direction, the average IMTs estimated by the improved technique and the previous method were 502+/-61 and 558+/-120 µm, respectively, showing a decrease in the standard deviation by the proposed method. Moreover, the result obtained by the improved technique presented only 0.4% difference between the automatically detected boundary and the manually detected boundary, which is smaller than that obtained by the previous method (10.7% difference). These results verified that the boundary detected by the improved technique was more accurate than that detected by the previous method.

  9. Identification of arterial wall dynamics in conscious dogs.

    Science.gov (United States)

    Gamero, L G; Armentano, R L; Barra, J G; Simon, A; Levenson, J

    2001-07-01

    Viscoelastic properties determine the dynamic behaviour of the arterial wall under pulsatile pressure and flow, suggesting time- or frequency-dependent responses to changes in wall stress and strain. The objectives of the present study were: (i) to develop a simplified model to derive simultaneously the elastic, viscous and inertial wall moduli; (ii) to assess Young's modulus as a function of frequency, in conscious, chronically instrumented dogs. Parametric discrete time models were used to characterise the dynamics of the arterial system based on thoracic aortic pressure (microtransducer) and diameter (sonomicrometry) measurements in control steady state and during activation of smooth muscle with the alpha-adrenoceptor agonist phenylephrine (5 microg kg(-1) min(-1), I.V.), in eight conscious dogs. The linear autoregressive model and a physically motivated non-linear model were fitted to the input-output (stress-strain) relationship. The aortic buffering function (complex Young's modulus) was obtained in vivo from the identified linear model. Elastic, viscous and inertial moduli were significantly increased from control state ((44.5 +/- 7.7) x 10(4) Pa; (12.3 +/- 4.7) x 10(4) Pa s; (0.048 +/- 0.028) x 10(4) Pa s(2) ) to active state ((85.3 +/- 29.5) x 10(4) Pa, P model, did not present significant differences compared with those derived using the non-linear model. In control conditions, the magnitude of the normalised complex Young's modulus was found to be similar to that reported in previous animal studies ranging from 1 to 10 Hz. During vascular smooth muscle activation, this modulus was found to be increased with regard to control conditions (P parametric modelling approach allows us to verify that vascular smooth muscle activation increases the elastic, viscous and inertial moduli with the advantage of being able to track their time evolution. Furthermore, under activation, the aortic wall remains stiff in the physiological frequency range, suggesting the

  10. Effect of Mould Wall Thickness on Rate of Solidification of Centrifugal Casting

    Directory of Open Access Journals (Sweden)

    Madhusudhan

    2010-11-01

    Full Text Available In Centrifugal Casting process the centrifugal force presses the metal against the inner wall of the metal mould, resulting in rapid solidification of the molten metal. However the solidification structures like structural uniformity and structural character of the solidified metal of centrifugal casting is of great importance, regarding to its mechanical properties. The solidification time of the casting is dependent upon the various parameters like speed ofrotation of the mold, mould wall temperature, heat transfer coefficient at the metal-mold interface, mould wall thickness, material of the mould and so on. In this paper experimental study of effect of mould wall thickness on solidification of the centrifugal casting has been discussed. As the mould wall thickness increases, due to the chilling effect, the solidification time decreases. Fine grains are observed in castings produced in thick walled mould and coarse grains are observed in thin walled moulds. Brinel Hardness of the casting was measured.

  11. The Association of Coronary Artery Calcification and Carotid Artery Intima-Media Thickness With Distinct, Traditional Coronary Artery Disease Risk Factors in Asymptomatic Adults

    OpenAIRE

    Rampersaud, Evadnie; Bielak, Lawrence F.; Parsa, Afshin; Shen, Haiqing; Post, Wendy; Ryan, Kathleen A.; Donnelly, Patrick; Rumberger, John A.; Sheedy, Patrick F; Peyser, Patricia A.; Shuldiner, Alan R.; Mitchell, Braxton D.

    2008-01-01

    Coronary artery calcification (CAC) and common carotid artery intima-media thickness (CIMT) are measures of subclinical vascular disease. This 2000–2006 study aimed to characterize the associations among coronary artery disease risk factors, CAC quantity, and CIMT and to estimate shared genetic and environmental contributions to both CAC and CIMT among 478 asymptomatic Amish adults in Lancaster County, Pennsylvania. Heritability for CAC quantity and CIMT, adjusted for age and sex, was 0.42 (P...

  12. The influence of fiber thickness, wall thickness and gap distance on the spiral nanofibrous scaffolds for bone tissue engineering

    International Nuclear Information System (INIS)

    We have developed a 3D nanofibrous spiral scaffold for bone tissue engineering which has shown enhanced cell attachment, proliferation and differentiation compared to traditional cylindrical scaffolds due to the spiral structures and the nanofiber incorporation. Some important parameters of these spiral scaffolds including gap distance, wall thickness and especially fiber thickness are crucial to the performance of the spiral structured scaffolds. In this study, we investigated the fiber thickness, gap distance and wall thickness of the spiral structure on the behavior of osteoblast cells. The human osteoblast cells are seeded on spiral structured scaffolds with various fiber thickness, gap distance and wall thickness and cell attachment, proliferation, differentiation and mineralized matrix deposition on the scaffolds are evaluated. It was found that increasing the thickness of nanofiber layer not only limited the cell infiltration into the scaffolds, but also restrained the osteoblastic cell phenotype development. Moreover, the geometric effect studies indicated that scaffolds with the thinner wall and gap distance 0.2 mm show the best bioactivity for osteoblasts.

  13. Clinical Significance of Arterial Stiffness and Thickness Biomarkers in Type 2 Diabetes Mellitus: An Up-To-Date Meta-Analysis

    OpenAIRE

    Yapei, Yang; Xiaoyan, Ren; Sha, Zeng; Li, Pan; Xiao, Meng; Shuangfeng, Chen; Lexin, Wang; Lianqun, Cui

    2015-01-01

    Background Type 2 Diabetes mellitus (T2DM) is associated with increased risk of cardiovascular disease (CVD). Previous studies explored the association of T2DM with arterial stiffness and thickness biomarkers including the augmentation index (AIX), aortic pulse wave velocity (aPWV), brachial-ankle PWV (baPWV), carotid intima-media wall thickness (IMT) as well as blood pressure (BP), low density lipoprotein cholesterol (LDL-C); however the conclusions are either inconsistent or incomprehensive...

  14. Nanotube wall thickness dependent magnetization reversal properties of NiFe nanotubes

    Science.gov (United States)

    Sharif, R.; Shamaila, S.; Shaheen, F.; Naseem, S.; Chen, J. Y.; Khaleeq-ur-Rahman, M.; Hussain, K.; Han, X. F.

    2013-01-01

    Nanotube wall thickness dependent magnetization properties of NiFe nanotube arrays electrodeposited in polycarbonate membranes are investigated. A systematic variation of nanotube wall thickness (tw) has been investigated. The magnetization reversal properties are strongly influenced by the variation of tw keeping length and external radius constant.

  15. Expectancy for developed pipe wall thickness measurement method in pipe wall thinning management of nuclear power plant

    International Nuclear Information System (INIS)

    Pipe wall thinning management is one of important items to keep safe nuclear power plant operation. In pipe wall thinning management, accurate understanding of wall thinning behavior is required, because pipe replacement period is evaluated by the result of pipe wall thickness measurement. In recently, not only current method 'UT' and 'RT' but also new nondestructive tests are being developed by many institutes. More advanced management will be achieved by these new monitoring systems. In this paper, developed status of these new monitoring systems are described with expected advanced pipe wall thinning management. (author)

  16. Methods for determining the wall thickness variation of tubular heaters used in thermalhydraulic studies

    International Nuclear Information System (INIS)

    Fuel bundle simulators used in thermalhydraulic studies typically consist of bundles of directly heated tubes. It is usually assumed that the heater tubes have a uniform circumferential heat flux distribution. In practice, this heat flux distribution is never exactly uniform because of wall thickness variations and bore eccentricity. Ignoring the non-uniformity in wall thickness can lead to under-estimating the local heat transfer coefficients. During nucleate boiling tests in a 5x5 PWR-type bundle subassembly at CEA-Grenoble, a sinusoidal temperature distribution was observed around the inside circumference of the heater rods. These heater rods were equipped with high-accuracy sliding thermocouple probes that permit the detailed measurement of the internal wall temperature distribution, both axially and circumferentially. The sinusoidal temperature distribution strongly suggests a variation in wall thickness. A methodology was subsequently derived to determine the circumferential wall thickness variation. The method is based on the principle that for directly heated fuel-element simulators, the nucleate boiling wall superheat at high pressures is nearly uniform around the heater rod circumference. The results show wall thickness variations of up to ±4% which was confirmed by subsequent ultrasonic wall-thickness measurements performed after bundle disassembly. Non-uniformities in circumferential temperature distributions were also observed during parallel thermalhydraulic tests at the University of Ottawa (UofO) on an electrically heated tube cooled internally by R-134a and equipped with fixed thermocouples on the outside. From the measured wall temperatures and knowledge of the inside heat transfer coefficient or wall temperature distribution, the variations in wall thickness and surface heat flux to the coolant were evaluated by solving conduction equations using three separate sets of data (1) single phase heat transfer data, (2) nucleate boiling data, and (3

  17. Measurement of Elastic Moduli of the Arterial Wall at Multiple Frequencies by Remote Actuation for Assessment of Viscoelasticity

    Science.gov (United States)

    Hasegawa, Hideyuki; Kanai, Hiroshi

    2004-05-01

    To characterize tissues in atherosclerotic plaques, we have developed a method, the phased tracking method, for measuring the strain (change in wall thickness) and elasticity of the arterial wall. However, some types of tissue, such as lipids and blood clots, cannot be discriminated from each other based only on elasticity due to the small difference in their elasticity. For more precise tissue characterization, we have measured the regional viscoelasticity. To obtain the viscoelasticity, in this study, elastic moduli at multiple frequencies were measured with ultrasound by generating the change in internal pressure due to remote cyclic actuation. Furthermore, the viscoelasticity of the arterial wall was estimated from the measured elastic moduli at multiple actuation frequencies.

  18. Differential Associations of Weight Dynamics With Coronary Artery Calcium Versus Common Carotid Artery Intima-Media Thickness: The CARDIA Study

    OpenAIRE

    Lee, Duk-Hee; Steffes, Michael W.; Gross, Myron; Park, Kyong; Holvoet, Paul; Kiefe, Catarina I.; Lewis, Cora E.; Jacobs, David R.

    2010-01-01

    Change and fluctuation in body mass index (BMI; weight (kg)/height (m)2) may be associated differently with coronary artery calcification (CAC) than with carotid artery intima-media thickness (IMT). The authors analyzed data on 2,243 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, initially aged 18–30 years, who were examined every 2–5 years over a 20-year period (1985–2006). BMI at year 0 was associated positively and linearly with CAC at year 20; however...

  19. Increased Coronary Vessel Wall Thickness in HIV-Infected Young Adults

    OpenAIRE

    Abd-Elmoniem, Khaled Z.; Unsal, Aylin B.; Eshera, Sarah; Matta, Jatin R.; Muldoon, Nancy; McAreavey, Dorothea; Purdy, Julia B.; HAZRA, Rohan; Hadigan, Colleen; Gharib, Ahmed M.

    2014-01-01

    Young adults infected with HIV early in life have significantly thicker right coronary artery walls than controls as measured by black-blood coronary magnetic resonance imaging. Vessel wall thickening in patients correlated with length of antiretroviral exposure, smoking pack-years, and hyperlipidemia.

  20. Sonographic Measurement of AP Diameter and Wall Thickness of the Gallbladder

    International Nuclear Information System (INIS)

    Call bladder size and wall thickness are important in the assessment of the pathologic condition. Authors have measured AP diameter of gallbladder and evaluated the change of all thickness between fasting and postprandial state. The results were as follows: 1. The mean of AP diameter was 2.18+0.49cm 2. The wall thickness was 2.7+0.6mm in fasting state and 3.3+0.8mm after meal. 3. The increase of wall thickness after fat meal was significant statistically(p<.001)

  1. Comparison of intima-media thickness and ophthalmic artery resistance index for assessing subclinical atherosclerosis in HIV-1-infected patients

    Directory of Open Access Journals (Sweden)

    Tana Mariangela

    2011-04-01

    Full Text Available Abstract Background Human immunodeficiency virus (HIV infection and antiretroviral treatment are associated with metabolic and cardiovascular complications that potentially increase the risk of atherosclerosis and cardiovascular disease in this population. Measurement of arterial wall thickness has been used as a surrogate of extent, severity and progression of atherosclerosis. A cross-sectional cohort study was performed to compare the validity of two non-invasive arterial measures: carotid intima-media thickness (IMT, a parameter of atherosclerosis, and ophthalmic artery resistance index (OARI, an index of occlusive carotid artery disease. Methods A total of 95 patients receiving highly active antiretroviral therapy (HAART for more than 12 months were consecutively enrolled. IMT and OARI were measured by 7.5 MHz linear probe. Results There was a significant linear increase in IMT and OARI values as the grade of cardiovascular risk (0.70 and 0.69 for very low risk, 0.86 and 0.72 for low risk and 0.98 and 0.74 for medium/high risk, p 0.83 and an OARI > 0.72 were the most discriminatory values for predicting a cardiovascular risk ≥ 10% (sensibility 89.6% and 75.8%; sensitivity 70.5% and 68.4%; p Conclusions Our data indicate that OARI may have a potential as a new precocious marker of subclinical atherosclerosis in HIV-1-infected patients.

  2. Analysis of Thick-Walled Cylinder Temperature Field based on the Thermal-Fluid-Solid Coupling

    Directory of Open Access Journals (Sweden)

    Yonghai Wu

    2013-04-01

    Full Text Available The barrel is a special thick-walled cylinder. It is significance to study the temperature distribution of thick-walled cylinder under liquid-cooled state to weapon launch safety and effectiveness. Taking a naval gun barrel as research objective, a unified thermal-fluid-solid coupling model is put forward including barrel solid wall, the cooling water and the water jacket solid wall. The unsteady coupled temperature field of the barrel is calculated at the time of single and continuous firing and some influencing factors such as cooling water flow velocity, barrel wall thickness and so on, are analyzed to the barrel temperature field. The results show that the water cooling effect of the barrel outer is closely related to the wall thickness and the cooling water flow velocity. When the barrel wall thickness is small, increasing the flow velocity increase heat dissipation and reduce barrel wall temperature obviously. When the barrel wall thickness is large, the water cooling effect depends on the total cooling time and small correlation with the velocity of cooling water flow.

  3. Thickness measurement of A-1 reactor caisson tube walls

    International Nuclear Information System (INIS)

    The equipment is described of measuring the thickness of caisson pipes built in the Bohunice A-1 reactor. The pulse-type ultrasonic thickness gauge is based on the reflection method using the double probe. The measurement accuracy is 0.1 mm. (J.B.)

  4. Quantifying [F-18]fluorodeoxyglucose uptake in the arterial wall

    DEFF Research Database (Denmark)

    Blomberg, Björn Alexander; Bashyam, A.; Ramachandran, A.;

    2015-01-01

    with contrast-enhanced CT (CECT) assistance on quantification of arterial wall F-18-FDG uptake at different imaging time-points. Methods Ten subjects were assessed by CECT imaging and dual time-point PET/CT imaging at approximately 60 and 180 min after F-18-FDG administration. For both time......-points, uptake of F-18-FDG was determined in the aortic wall by calculating the blood pool-corrected maximum standardized uptake value (cSUV(MAX)) and cSUV(MEAN). The PVE-corrected SUVMEAN (pvcSUV(MEAN)) was also calculated using F-18-FDG PET/CT and CECT images. Finally, corresponding target-to-background ratios...... (TBR) were calculated. Results At 60 min, pvcSUV(MEAN) was on average 3.1 times greater than cSUV(MAX) (P <.0001) and 8.5 times greater than cSUV(MEAN) (P <.0001). At 180 min, pvcSUV(MEAN) was on average 2.6 times greater than cSUV(MAX) (P <.0001) and 6.6 times greater than cSUV(MEAN) (P <.0001...

  5. Study on fluidity of squeeze cast AZ91D magnesium alloy with different wall thicknesses

    Directory of Open Access Journals (Sweden)

    Chen Yun

    2014-03-01

    Full Text Available Rectangular cross-section specimens with different section thicknesses were prepared to study the influences of pouring temperature, mould temperature and squeeze velocity on the fluidity of squeeze cast AZ91D magnesium alloy by means of orthogonal test design method. The results show that pouring temperature, mould temperature and squeeze velocity can significantly affect the fluidity of magnesium alloy specimens with wall thickness no more than 4 mm, and the pouring temperature is the most influential factor on the fluidity of specimens with wall thickness of 1, 2 and 3 mm, while mould temperature is the one for specimens with wall thickness of 4 mm. Increasing pouring temperature between 700 °C and 750 °C is beneficial to the fluidity of AZ91D magnesium alloy, and increasing mould temperature significantly enhances the filling ability of thick (3 and 4 mm section castings. The fluidity of squeeze cast magnesium alloy increases with the increase of wall thickness. It is not recommended to produce magnesium alloy casting with wall thickness of smaller than 3 mm by squeeze cast process due to the poor fluidity. The software DPS was used to generate the regression model, and linear regression equations of the fluidity of squeeze cast AZ91D with different wall thicknesses are obtained using the test results.

  6. Epicardial adipose tissue and pericoronary fat thickness measured with 64-multidetector computed tomography: potential predictors of the severity of coronary artery disease

    International Nuclear Information System (INIS)

    Objective: the aim of the present study was to investigate the relationship between pericoronary fat and the severity and extent of atherosclerosis, quantified using 64-multidetector computed tomography, in patients with suspected coronary artery disease. Methods: the study population consisted of 131 patients who were clinically referred for noninvasive multislice computed tomography coronary angiography for the evaluation of coronary artery disease. Patients were classified as follows: no atherosclerosis, Group 1; nonobstructive atherosclerosis (luminal narrowing < 50% in diameter), Group 2; and obstructive atherosclerosis (luminal narrowing ≧ 50%) in a single vessel or obstructive atherosclerosis in the left main coronary artery and/or multiple vessels, Group 3. Epicardial adipose tissue was defined as the adipose tissue between the surface of the heart and the visceral layer of the pericardium (visceral epicardium). Epicardial adipose tissue thickness (mm) was determined in the right ventricular anterior free wall. The mean thickness of the pericoronary fat surrounding the three coronary arteries was used for the analyses. Results: the average thickness over all three regions was 13.2 ± 2.1 mm. The pericoronary fat thickness was significantly increased in Group 3 compared with Groups 2 and 1. The epicardial adipose tissue thickness was significantly increased in Group 3 compared with Groups 2 and 1. A receiver operating characteristic curve for obstructive coronary artery disease was assessed to verify the optimum cut-off point for pericoronary fat thickness, which was 13.8 mm. A receiver operating characteristic curve for obstructive coronary artery disease was also assessed to verify the optimum cut-off point for epicardial adipose tissue, which was 6.8 cm. Conclusion: we showed that the epicardial adipose tissue and pericoronary fat thickness scores were higher in patients with obstructive coronary artery diseases. (author)

  7. Epicardial adipose tissue and pericoronary fat thickness measured with 64-multidetector computed tomography: potential predictors of the severity of coronary artery disease

    Energy Technology Data Exchange (ETDEWEB)

    Demircelik, Muhammed Bora; Gurel, Ozgul Malcok; Selcoki, Yusuf; Atar, Inci Asli; Eryonucu, Beyhan, E-mail: drdemircelik@yahoo.com [Turgut Ozal Univercity, Department of Cardiology, Ankara (Turkey); Bozkurt, Alper; Akin, Kayihan [Turgut Ozal Univercity, Department of Radiology, Ankara (Turkey); Yilmaz, Omer Caglar [Ankara Occupational Diseases Hospital, Department of Cardiology, Ankara (Turkey)

    2014-06-15

    Objective: the aim of the present study was to investigate the relationship between pericoronary fat and the severity and extent of atherosclerosis, quantified using 64-multidetector computed tomography, in patients with suspected coronary artery disease. Methods: the study population consisted of 131 patients who were clinically referred for noninvasive multislice computed tomography coronary angiography for the evaluation of coronary artery disease. Patients were classified as follows: no atherosclerosis, Group 1; nonobstructive atherosclerosis (luminal narrowing < 50% in diameter), Group 2; and obstructive atherosclerosis (luminal narrowing ≧ 50%) in a single vessel or obstructive atherosclerosis in the left main coronary artery and/or multiple vessels, Group 3. Epicardial adipose tissue was defined as the adipose tissue between the surface of the heart and the visceral layer of the pericardium (visceral epicardium). Epicardial adipose tissue thickness (mm) was determined in the right ventricular anterior free wall. The mean thickness of the pericoronary fat surrounding the three coronary arteries was used for the analyses. Results: the average thickness over all three regions was 13.2 ± 2.1 mm. The pericoronary fat thickness was significantly increased in Group 3 compared with Groups 2 and 1. The epicardial adipose tissue thickness was significantly increased in Group 3 compared with Groups 2 and 1. A receiver operating characteristic curve for obstructive coronary artery disease was assessed to verify the optimum cut-off point for pericoronary fat thickness, which was 13.8 mm. A receiver operating characteristic curve for obstructive coronary artery disease was also assessed to verify the optimum cut-off point for epicardial adipose tissue, which was 6.8 cm. Conclusion: we showed that the epicardial adipose tissue and pericoronary fat thickness scores were higher in patients with obstructive coronary artery diseases. (author)

  8. Determination of the Normal Bladder Wall Thickness in Adults by Trans Abdominal Ultrasound

    Directory of Open Access Journals (Sweden)

    Fakher Rahim

    2010-05-01

    Full Text Available Background/Objective: Bladder in mature subjects can be affected by various maladies, which cause the wall thickness in the local or emission manner. Trans-abdominal ultrasonography of the bladder is one of the current methods of recognition of bladder maladies. This research aimed to measure the natural posterior-inferior and lateral wall thickness of the bladder, which is performed by ultrasonography. "nPatients and Methods: A total of 280 individuals (160 men, 120 women in the age range of 15-25 years old, admitted to the ultrasonography unit of Imam Khomeini Hospital of Ahwaz from 31 August 2008 to 2009 were enrolled into the study. The ultrasonography was performed in sagittal and axial positions. "nResults: The mean of the posterior inferior wall thickness was 2.22±0.52 mm, the mean of the lateral wall thickness was 2.24±0.52, the thickness of the posterior-inferior wall in men was 2.02±0.5 mm, and the thickness of the posterior-inferior wall in women was 2.23±0.54 mm. Similarly, the thickness of the lateral wall was 2.22±0.51 mm in men and the thickness of the wall was 2.26 ± 0/54 mm for women. The thickness of the posterior-inferior wall in the 15-19 years age group was 1.93±0.42 mm and in the 20-25 years age group was 2.47±0.46 mm. The thickness of the lateral wall in the 15-19 years age group was 1-96±0.43 years and in the 20-25 years age group was 247±0.46 mm."nConclusion: By gathering information about normal bladder wall thickness, ultrasound can help the pathologist or urologist in the diagnosis and suspicion, especially in cases such as cyst, neurogenic bladder wall and/or infiltration of the bladder wall.

  9. Simultaneous identification of elastic properties, thickness, and diameter of arteries excited with ultrasound radiation force.

    Science.gov (United States)

    Dutta, Parikshit; Urban, Matthew W; Le Maître, Olivier P; Greenleaf, James F; Aquino, Wilkins

    2015-07-01

    The elastic and geometric properties of arteries have been long recognized as important predictors of cardiovascular disease. This work presents a robust technique for the noninvasive characterization of anisotropic elastic properties as well as thickness and diameter in arterial vessels. In our approach, guided waves are excited along arteries using the radiation force of ultrasound. Group velocity is used as the quantity of interest to reconstruct elastic and geometric features of the vessels. One of the main contributions of this work is a systematic approach based on sparse-grid collocation interpolation to construct surrogate models of arteries. These surrogate models are in turn used with direct-search optimization techniques to produce fast and accurate estimates of elastic properties, diameter, and thickness. One of the attractive features of the proposed approach is that once a surrogate model is built, it can be used for near real-time identification across many different types of arteries. We demonstrate the feasibility of the method using simulated and in vitro laboratory experiments on a silicon rubber tube and a porcine carotid artery. Our results show that using our proposed method, we can reliably identify the longitudinal modulus, thickness, and diameter of arteries. The circumferential modulus was found to have little influence in the group velocity, which renders the former quantity unidentifiable using the current experimental setting. Future work will consider the measurement of circumferential waves with the objective of improving the identifiability of the circumferential modulus. PMID:26109582

  10. Simultaneous identification of elastic properties, thickness, and diameter of arteries excited with ultrasound radiation force

    International Nuclear Information System (INIS)

    The elastic and geometric properties of arteries have been long recognized as important predictors of cardiovascular disease. This work presents a robust technique for the noninvasive characterization of anisotropic elastic properties as well as thickness and diameter in arterial vessels. In our approach, guided waves are excited along arteries using the radiation force of ultrasound. Group velocity is used as the quantity of interest to reconstruct elastic and geometric features of the vessels. One of the main contributions of this work is a systematic approach based on sparse-grid collocation interpolation to construct surrogate models of arteries. These surrogate models are in turn used with direct-search optimization techniques to produce fast and accurate estimates of elastic properties, diameter, and thickness. One of the attractive features of the proposed approach is that once a surrogate model is built, it can be used for near real-time identification across many different types of arteries. We demonstrate the feasibility of the method using simulated and in vitro laboratory experiments on a silicon rubber tube and a porcine carotid artery. Our results show that using our proposed method, we can reliably identify the longitudinal modulus, thickness, and diameter of arteries. The circumferential modulus was found to have little influence in the group velocity, which renders the former quantity unidentifiable using the current experimental setting. Future work will consider the measurement of circumferential waves with the objective of improving the identifiability of the circumferential modulus. (paper)

  11. Ultrasonic Measurement of Change in Elasticity due to Endothelium Dependent Relaxation Response by Accurate Detection of Artery-Wall Boundary

    Science.gov (United States)

    Kaneko, Takuya; Hasegawa, Hideyuki; Kanai, Hiroshi

    2007-07-01

    Ross hypothesized that an endothelial dysfunction is considered to be an initial step in atherosclerosis. Endothelial cells, which release nitric oxide (NO) in response to shear stress from blood flow, have a function of relaxing smooth muscle in the media of the arterial wall. For the assessment of the endothelial function, there is a conventional method in which the change in the diameter of the brachial artery caused by flow-mediated dilation (FMD) is measured with ultrasound. However, despite the fact that the collagen-rich hard adventitia does not respond to NO, the conventional method measures the change in diameter depending on the mechanical property of the entire wall including the adventitia. Therefore, we developed a method of measuring the change in the thickness and the elasticity of the brachial artery during a cardiac cycle using the phased tracking method for the evaluation of the mechanical property of only the intima-media region. In this study, the initial positions of echoes from the lumen-intima and media-adventitia boundaries are determined using complex template matching to accurately estimate the minute change in the thickness and the elasticity of the brachial and radial arteries. The ambiguity in the determination of such boundaries was eliminated using complex template matching, and the change in elasticity measured by the proposed method was larger than the change in inner diameter obtained by the conventional method.

  12. MRI-based Determination of Reference Values of Thoracic Aortic Wall Thickness in a General Population

    Energy Technology Data Exchange (ETDEWEB)

    Mensel, Birger; Quadrat, Alexander; Schneider, Tobias; Kuehn, Jens-Peter; Hegenscheid, Katrin [University Medicine Greifswald, Institute of Diagnostic Radiology and Neuroradiology, Greifswald (Germany); Doerr, Marcus [University Medicine Greifswald, Department of Internal Medicine, Greifswald (Germany); DZHK (German Center for Cardiovascular Research), Greifswald (Germany); Voelzke, Henry [University Medicine Greifswald, Institute for Community Medicine, Greifswald (Germany); DZHK (German Center for Cardiovascular Research), Greifswald (Germany); Lieb, Wolfgang [Christian Albrechts University, Institute of Epidemiology, Kiel (Germany); Lorbeer, Roberto [University Medicine Greifswald, Institute for Community Medicine, Greifswald (Germany)

    2014-09-15

    To provide age- and sex-specific reference values for MRI-derived wall thickness of the ascending and descending aorta in the general population. Data of 753 subjects (311 females) aged 21-81 years were analysed. MRI was used to determine the aortic wall thickness (AWT). Equations for reference value calculation according to age were established for females and males. Median wall thickness of the ascending aorta was 1.46 mm (5th-95th range: 1.15-1.88 mm) for females and 1.56 mm (1.22-1.99 mm) for males. Median wall thickness of the descending aorta was 1.26 mm (0.97-1.58 mm) in females and 1.36 mm (1.04-1.75 mm) in males. While median and 5th and 95th percentiles for the ascending and descending aorta increased with age in both sexes, the association between age and median AWT was stronger in males than in females for both the ascending and descending aorta. Reference values for the ascending and descending AWT are provided. In a healthy sample from the general population, the wall of the ascending aorta is thicker than the wall of the descending aorta, and both walls are thicker in males than females. The increase in wall thickness with age is greater in males. (orig.)

  13. CARDIAC TRANSPLANT REJECTION AND NON-INVASIVE COMON CAROTID ARTERY WALL FUNCTIONAL INDICES

    Directory of Open Access Journals (Sweden)

    A. O. Shevchenko

    2015-01-01

    Full Text Available Allograft rejection would entail an increase in certain blood biomarkers and active substances derived from activated inflammatory cells which could influence entire vascular endothelial function and deteriorate arterial wall stiffness. We propose that carotid wall functional indices measured with non-invasive ultrasound could we valuable markers of the subclinical cardiac allograft rejection. Aim. Our goal was to analyze the clinical utility of functional common carotid wall (CCW variables measured with high-resolution Doppler ultrasound as a non-invasive screening tool for allograft rejection in cardiac transplant patients (pts. Methods. One hundred and seventy one pts included 93 cardiac recipients, 30 dilated cardiomyopathy waiting list pts, and 48 stable coronary artery disease (SCAD pts without decompensated heart failure were included. Along with resistive index (Ri, pulsative index (Pi, and CCW intima-media thickness (IMT, CCW rigidity index (iRIG was estimated using empirical equation. Non-invasive evaluation was performed in cardiac transplant recipients prior the endomyo- cardial biopsy. Results. Neither of Ri, Pi, or CCW IMT were different in studied subgroups. iRIG was signifi- cantly lower in SCAD pts when compared to the dilated cardiomyopathy subgroup. The later had similar values with cardiac transplant recipients without rejection. Antibody-mediated and cellular rejection were found in 22 (23.7% and 17 (18.3% cardiac recipients, respectively. Mean iRIG in pts without rejection was significantly lower in comparison to antibody-mediated rejection and cell-mediated (5514.7 ± 2404.0 vs 11856.1 ± 6643.5 and 16071.9 ± 10029.1 cm/sec2, respectively, p = 0.001. Area under ROC for iRIG was 0.90 ± 0.03 units2. Analysis showed that iRIG values above estimated treshold 7172 cm/sec2 suggested relative risk of any type of rejection 17.7 (95%CI = 6.3–49.9 sensitivity 80.5%, specificity – 81.1%, negative predictive value – 84

  14. Space-resolved Resistive Measurement of Liquid Metal Wall Thickness

    CERN Document Server

    Mirhoseini, S M H

    2016-01-01

    In a fusion reactor internally coated with liquid metal, it will be important to diagnose the thickness of the liquid at various locations in the vessel, as a function of time, and possibly respond to counteract undesired bulging or depletion. The electrical conductance between electrodes immersed in the liquid metal can be used as a simple proxy for the local thickness. Here a matrix of electrodes is shown to provide spatially resolved measurements of liquid metal thickness in the absence of plasma. First a theory is developed for mxn electrodes, and then it is experimentally demonstrated for 3x1 electrodes. The experiments were carried out with Galinstan, but are easily extended to Lithium or other liquid metals.

  15. Reconstruction of full thickness abdominal wall defect following tumor resection: A case report

    Directory of Open Access Journals (Sweden)

    Kovačević Predrag

    2014-01-01

    Full Text Available Introduction. Reconstruction of a full thickness abdominal wall defect is a demanding procedure for general and also for plastic surgeons, requiring vigorous planning and reconstruction of three layers. Case Outline. We present a case of a 70-year-old patient with a huge abdominal wall tumor with 40 years evolution. Surgery was performed under general anesthesia. Full thickness abdominal defect appeared after the tumor resection. Reconstruction followed in the same act. The defect was reconstructed using a combination of techniques, including omental flap, fascia lata graft, local skin flaps and skin grafts. After surgery no major complications were noted, only a partial skin flap loss, which was repaired using partial thickness skin grafts. The final result was described by the patient as very good, without hernia formation. Conclusion. Omenthoplasty, abdominal wall reconstruction in combination with free fascia lata graft and skin grafts can be one of good options for the reconstruction of full thickness abdominal wall defects.

  16. Extreme value statistical analysis for wall thickness of elbow part of carbon steel tube

    International Nuclear Information System (INIS)

    Relating to the resent accident occurred in Mihama Nuclear Power Plant, the estimation method of the minimum value of the wall thickness of carbon steel pipes is concerned, because the minimum wall thickness value is required to decide the exact replacement time of the pipe. Currently in the nuclear power plants, the wall thickness is measured by the ultra-sonic method and the minimum value of the wall thickness decided from the smallest value among 8 values which are obtained at 8 points set around the circumference of the pipes. The minimum value thus determined, however, is not true minimum value and the exact minimum value could be determined by the Extreme Value Statistical Analysis applying for 8 measurement values. This study aims to analyze the field data on the elbow part of carbon steel pipes in order to demonstrate the usefulness of the Extreme Value Statistical Analysis. (author)

  17. Mitigating the effects of surface morphology changes during ultrasonic wall thickness monitoring

    Science.gov (United States)

    Cegla, Frederic; Gajdacsi, Attila

    2016-02-01

    Ultrasonic wall thickness monitoring using permanently installed sensors has become a tool to monitor pipe wall thicknesses online and during plant operation. The repeatability of measurements with permanently installed transducers is excellent and can be in the nanometer range. It has, however, also been shown that the measured wall thickness is dependent on surface morphology and that when there are changes in surface morphology the monitored thickness trends can be affected. With an adaptive cross correlation approach, this effect can be successfully muted. However, under some surface morphology change conditions, this can also lead to inaccuracies. Here, an approach to detect when surface morphology changes can influence trend accuracies is presented. This method requires the combination of measurements from several sensors that independently sample an area where the same wall loss mechanism is assumed to occur. Simulation results for the effectiveness of the technique are presented.

  18. Effect of cigarette smoke, nicotine, and carbon monoxide on the permeability of the arterial wall

    International Nuclear Information System (INIS)

    The association between cigarette smoking and the development of atherosclerosis is well established, but the mechanism that makes cigarettes such a potent risk factor is not understood. There is normally a constant insudation of plasma macromolecules into the arterial wall. Fibrinogen and lipids are two of the large molecules involved in atherosclerosis. Therefore, we studied the effect of cigarette smoke, nicotine, and carbon monoxide on the permeability of the canine arterial wall to 125I-labeled fibrinogen. The results show that inhaled cigarette smoke significantly and rapidly increases the permeability of the arterial wall to fibrinogen and that this effect can be produced with carbon monoxide alone but not with intravenous nicotine

  19. Determination of the Normal Bladder Wall Thickness in Adults by Trans Abdominal Ultrasound

    OpenAIRE

    Fakher Rahim; Fariba Afrakhteh; Ahmad Fakhri Zahed; Mohammad Davoudi

    2010-01-01

    Background/Objective: Bladder in mature subjects can be affected by various maladies, which cause the wall thickness in the local or emission manner. Trans-abdominal ultrasonography of the bladder is one of the current methods of recognition of bladder maladies. This research aimed to measure the natural posterior-inferior and lateral wall thickness of the bladder, which is performed by ultrasonography. "nPatients and Methods: A total of 280 individuals (160 men, 120 women) in the age ra...

  20. Increased Bladder Wall Thickness in Diabetic and Nondiabetic Women With Overactive Bladder

    OpenAIRE

    UZUN, Hakkı; Ogullar, Sabri; Şahin, Serap Baydur; Zorba, Orhan Ünal; Akça, Görkem; Sümer, Fatih; Güney, Ülkü Mete; Balık, Gülşah

    2013-01-01

    Purpose Bladder wall thickness has been reported to be associated with overactive bladder (OAB) in women. Diabetic women have an increased risk for OAB syndrome and may have an increased risk for bladder wall thickness. Methods A total of 235 female patients aged 40 to 75 years were categorized into four groups. The first group consisted of women free of urgency or urge urinary incontinence. The second group included nondiabetic women with idiopathic OAB. The third group consisted of women wi...

  1. Quantitative CT measures of emphysema and airway wall thickness are related to D(L)CO

    DEFF Research Database (Denmark)

    Grydeland, Thomas B; Thorsen, Einar; Dirksen, Asger;

    2011-01-01

    There is limited knowledge on the relationship between diffusing capacity of the lung for carbon monoxide (D(L)CO) and quantitative computed tomography (CT) measures of emphysema and airway wall thickness.......There is limited knowledge on the relationship between diffusing capacity of the lung for carbon monoxide (D(L)CO) and quantitative computed tomography (CT) measures of emphysema and airway wall thickness....

  2. Using The Descending Aortic Wall Thickness Measured In Transesophageal Echocardiography As A Risk Marker For Aortic Dissection

    Directory of Open Access Journals (Sweden)

    Zaher Fanari

    2015-04-01

    Full Text Available Objective: The aim of this study is to estimate whether aortic wall thickness is increased in patients with Aortic dissection (AD compared to low risk control group and can be used in addition to aortic diameter as a risk marker of AD. Background: AD occurs due to pathologies that may increase thickness of the aortic wall. Transesophageal echocardiography (TEE has the ability to visualise both the thoracic aortic wall and lumen. Aortic diameter has been used to predict aortic dissection and timing of surgery, but it is not always predictive of that risk. Methods: In 48 patients with AD who underwent TEE were examined retrospectively and compared to 48 control patients with patent foramen ovale (PFO. We measured aortic diameter at different levels, intimal/medial thickness (IMT and complete wall thickness (CMT. Demographic data and cardiovascular risk factors were reviewed. The data was analysed using ANOVA and student t test. Results: (AD patients were older [mean age 66 AD vs. 51 PFO], had more hypertension, diabetes, hyperlipidemia and Coronary artery disease. Both IMT and CMT in the descending aorta were increased in AD group [(1.85 vs. 1.43 mm; P=0.03 and 2.93 vs. 2.46 mm; p=0.01. As expected the diameter of ascending aorta was also greater in AD (4.61 vs. 2.92 cm; P=0.004. Conclusions: CMT and IMT in the descending aorta detected by TEE is greater in patients with AD when compared to control and may add prognostic data to that of aortic diameter

  3. Using The Descending Aortic Wall Thickness Measured In Transesophageal Echocardiography As A Risk Marker For Aortic Dissection

    Science.gov (United States)

    Fanari, Zaher; Hammami, Sumaya; Hammami, Muhammad Baraa; Hammami, Safa; Eze-Nliam, Chete; Weintraub, William S.

    2015-01-01

    Objective The aim of this study is to estimate whether aortic wall thickness is increased in patients with Aortic dissection (AD) compared to low risk control group and can be used in addition to aortic diameter as a risk marker of AD. Background AD occurs due to pathologies that may increase thickness of the aortic wall. Transesophageal echocardiography (TEE) has the ability to visualize both the thoracic aortic wall and lumen. Aortic diameter has been used to predict aortic dissection and timing of surgery, but it is not always predictive of that risk. Methods In 48 patients with AD who underwent TEE were examined retrospectively and compared to 48 control patients with patent foramen ovale (PFO). We measured aortic diameter at different levels, intimal/medial thickness (IMT) and complete wall thickness (CMT). Demographic data and cardiovascular risk factors were reviewed. The data was analyzed using ANOVA and student t test. Results (AD) patients were older [mean age 66 AD vs. 51 PFO], had more hypertension, diabetes, hyperlipidemia and Coronary artery disease. Both IMT and CMT in the descending aorta were increased in AD group [(1.85 vs. 1.43 mm; P=0.03 and 2.93 vs. 2.46 mm; p=0.01). As expected the diameter of ascending aorta was also greater in AD (4.61 vs. 2.92 cm; P=0.004). Conclusions CMT and IMT in the descending aorta detected by TEE is greater in patients with AD when compared to control and may add prognostic data to that of aortic diameter. PMID:25984293

  4. Detection of Boundaries of Carotid Arterial Wall by Analyzing Ultrasonic RF Signals

    Science.gov (United States)

    Ibrahim, Nabilah; Hasegawa, Hideyuki; Kanai, Hiroshi

    2012-07-01

    In line with the fact that the intima-media thickness (IMT) of the carotid arterial wall is the most frequently used indicator to diagnose atherosclerosis by ultrasound, it is essential to accurately estimate the thickness of the intima-media complex (IMC) boundaries, i.e., the lumen-intima boundary (LIB) and media-adventitia boundary (MAB). In this study, an improved adaptive model of an ultrasonic echo was developed for the model to realize better fitting to the reference RF echo, which is measured from a glass plate, using a Gaussian window for the envelope function of the adaptive model. Using the mean squared error (MSE) method, the envelope of the improved adaptive model (multiply the sinusoidal wave with the Gaussian window) was fitted with the envelope of an RF echo measured in vivo to estimate the boundaries of the carotid arterial wall. Firstly, a computer simulation of the carotid arterial wall was conducted to evaluate the accuracy of boundary detection using the envelope of the improved adaptive model. In the simulation, IMT was set at 0.50 mm in a 7.2-mm-long short segment in the longitudinal direction. The IMT estimated by the proposed method was 0.54 mm. The 8% error between the true and detected IMTs showed the high accuracy of the envelope of the improved adaptive model in boundary detection. In the in vivo measurement, for the 4.8-mm-long short segment in the longitudinal direction, the average IMT automatically estimated by the proposed method was 0.57 mm. The result was compared with those obtained by the previous method and manually. The IMT estimated by the previous method, which uses an RF adaptive model, was 0.59 mm and the manually determined IMT was 0.56 mm. The smaller difference between the results obtained by the proposed method and manually verified that boundary detection by the proposed method was better than that by the previous method.

  5. Reliability assessment for thickness measurements of pipe wall using probability of detection

    International Nuclear Information System (INIS)

    This paper proposes a reliability assessment method for thickness measurements of pipe wall using probability of detection (POD). Thicknesses of pipes are measured by qualified inspectors with ultrasonic thickness gauges. The inspection results are affected by human factors of the inspectors and include some errors, because the inspectors have different experiences and frequency of inspections. In order to ensure reliability for inspection results, first, POD evaluates experimental results of pipe-wall thickness inspection. We verify that the results have differences depending on inspectors including qualified inspectors. Second, two human factors that affect POD are indicated. Finally, it is confirmed that POD can identify the human factors and ensure reliability for pipe-wall thickness inspections. (author)

  6. Prevalence and histopathological finding of thin-walled and thick-walled Sarcocysts in slaughtered cattle of Karaj abattoir, Iran.

    Science.gov (United States)

    Nourollahi-Fard, Saeid R; Kheirandish, Reza; Sattari, Saeid

    2015-06-01

    Sarcocystosis is a zoonotic disease caused by Sarcocystis spp. with obligatory two host life cycle generally alternating between an herbivorous intermediate host and a carnivorous definitive host. Some species of this coccidian parasite can cause considerable morbidity and mortality in cattle. The present study was set to investigate the prevalence of Sarcocystis spp. and type of cyst wall in slaughtered cattle of Karaj abattoir, Iran. For this purpose 125 cattle (88 males and 37 females) were investigated for the presence of macroscopic and microscopic Sarcocystis cysts in muscular tissues. No macroscopic Sarcocystis cysts were found in any of the samples. In light microscopy, 121 out of 125 cattle (96.8 %) had thin-walled cysts of Sarcocystis cruzi, while 43 out of them (34.4 %) had thick-walled Sarcocystis cyst. In this survey, the most infected tissue was esophagus and heart and the less was diaphragm. Thin-walled cysts (S. cruzi) mostly found in heart and skeletal muscle showed the less. However, thick-walled cyst (S. hominis or S. hirsuta) mostly were detected in diaphragm, heart muscle showed no thick-walled cyst. No significant relation was observed between age and sex and the rate of infection. The results showed that Sarcocystis cyst is prevalent in cattle in the North part of Iran and the evaluation of infection potential can be useful when considering control programs. PMID:26064016

  7. Post-cast EDM method for reducing the thickness of a turbine nozzle wall

    Science.gov (United States)

    Jones, Raymond Joseph; Bojappa, Parvangada Ganapathy; Kirkpatrick, Francis Lawrence; Schotsch, Margaret Jones; Rajan, Rajiv; Wei, Bin

    2002-01-01

    A post-cast EDM process is used to remove material from the interior surface of a nozzle vane cavity of a turbine. A thin electrode is passed through the cavity between opposite ends of the nozzle vane and displaced along the interior nozzle wall to remove the material along a predetermined path, thus reducing the thickness of the wall between the cavity and the external surface of the nozzle. In another form, an EDM process employing a profile as an electrode is disposed in the cavity and advanced against the wall to remove material from the wall until the final wall thickness is achieved, with the interior wall surface being complementary to the profile surface.

  8. Utilization of a global data grid repository in CAD assessment of carotid wall thickness

    Science.gov (United States)

    Gutierrez, Marco A.; Lee, Jasper; Zhou, Zheng; Pilon, Paulo E.; Lage, Silvia G.

    2007-03-01

    A CAD method of calculating wall thickness of carotid vessels addresses the time-consuming issue of using B-mode ultrasound as well as inter- and intra-observer variability in results. Upon selection of a region-of-interest and filtering of a series of ultrasound carotid images, the CAD is able to measure the geometry of the lumen and plaque surfaces using a least-square fitting of the active contours during systole and diastole. To evaluate the approach, ultrasound image sequences from 30 patients were submitted to the procedure. The images were stored on an international data grid repository that consists of three international sites: Image Processing and Informatics (IPI) Laboratory at University of Southern California, USA; InCor (Heart Institute) at Sao Paulo, Brazil, and Hong Kong Polytechnic University, Hong Kong. The three chosen sites are connected with high speed international networks including the Internet2, and the Brazilian National Research and Education Network (RNP2). The Data Grid was used to store, backup, and share the ultrasound images and analysis results, which provided a large-scale and a virtual data system. In order to study the variability between the automatic and manual definition of artery boundaries, the pooled mean and the standard deviation for the difference between measurements of lumen diameter were computed. The coefficient of variation and correlation were also calculated. For the studied population the difference between manual and automatic measurement of the lumen diameter (LD) and intima-media-thickness (IMT) were 0.12 +/-0.10 and 0.09+/- 0.06, respectively.

  9. Quality control in high thickness concrete walls for shielding

    International Nuclear Information System (INIS)

    After evaluating different methods of non-destructive testing, of fast execution and quick results, with low operative cost, and suitable to verify the homogeneity and the shielding power of the walls of process cells for radiochemical use, under construction in the Centro Atomico Ezeiza, it was decided to employ the ultrasound method over the whole surface to be examined, with subsequent verification of the results on isolated zones by means of radiometry and gammagraphy. This procedure proved to be satisfactory. The cell's characteristics, the tests performed and their results, which were statistically evaluated by means of a computer program, implemented to his effect, are described. (C.A.K.)

  10. Control on mine pressure of thick and strong roof stratum movement in long wall thick coal caving face

    Institute of Scientific and Technical Information of China (English)

    DENG Guang-zhe; ZHANG dian-chang; HE Tao

    2008-01-01

    The caving of thick and strong roof stratum causes tremendous rock pressurein mine. The results of the analysis on dynamic natures of actual measurements of somefields, of which the roof pressure can be caused by thick and strong stratum in long wallthick coal caving face, could present the relation between the collapse and movement ofthick and strong roof strata and surrounding rock pressure. In order to control the roofpressure effectively, the thick and strong roof strata, can be fractured and softened previ-ously by hydraulic fracturing and low-high pressure water infusion, fracturing and softeningmethod. The results of study can provide basis for strata control and safe management inlong wall thick coal caving face.

  11. RELATIONSHIP OF CAROTID ARTERIES INTIMA-MEDIA THICKNESS WITH INFECTIOUS, IMMUNE, METABOLIC FACTORS AND INFLAMMATION MARKERS IN HEALTHY PERSONS

    Directory of Open Access Journals (Sweden)

    A. P. Shavrin

    2014-07-01

    Full Text Available Aim – to examine the relationship of arteries wall thickness with the indicators characterizing the infectious, immune, metabolic status inapparently healthy individuals.Materials and methods. The study included 342 patients (mean age 43.7 ± 0.5 years that in the process of cluster analysis on the thicknessof the intima-media thickness (IMT were divided into 3 groups. Group 1 consisted of patients with no risk factors of cardiovascular disease,2nd – patients with presence of these factors, 3rd – patients with atherosclerotic plaques in the carotid artery. All patients were examinedin complex: ultrasound of vessels measurement on the Aloka 5000 with IMT, evaluation of lipid profile, glucose level, determination of C-reactive protein (CRP in blood plasma and cytokines – tumor necrosis factor-α (TNF-α, interferon-γ (IFN-γ, interleukin (IL -1, -8, -4, specific antibody immunoglobulin G (IgG to cytomegalovirus (CMV, herpes simplex virus type 1 (HSV-1 , C. pneumoniae, H. pylori and β-hemolytic streptococci group A. Immune system status was assessed by innate and acquired immunity factors.Results. In groups of examined patients by increasing IMT of the common carotid artery infectious viruses (CMV, HSV-1 burden increased,what was obligatory for all groups. In the 3rd group, in 45 % of patients C. pneumoniae was found. In the 2nd and 3rd groups weakening ofacquired immunity was found out – reducing the total number of lymphocytes and T-lymphocytes, the increase of CRP and proinflammatory cytokines (IL-1, -8, IFN-γ, TNF-α, it was indicating development of inflammatory process, and in the third group it took characters of the system inflammatory response. In cluster analysis it was revealed that the process of thickening of the vascular wall is influenced by complex factors – infectious, metabolic and immune.Conclusion. The presence of the close relationship between the thickness of vessel walls and infectious, metabolic (lipid and

  12. RELATIONSHIP OF CAROTID ARTERIES INTIMA-MEDIA THICKNESS WITH INFECTIOUS, IMMUNE, METABOLIC FACTORS AND INFLAMMATION MARKERS IN HEALTHY PERSONS

    Directory of Open Access Journals (Sweden)

    A. P. Shavrin

    2011-01-01

    Full Text Available Aim – to examine the relationship of arteries wall thickness with the indicators characterizing the infectious, immune, metabolic status inapparently healthy individuals.Materials and methods. The study included 342 patients (mean age 43.7 ± 0.5 years that in the process of cluster analysis on the thicknessof the intima-media thickness (IMT were divided into 3 groups. Group 1 consisted of patients with no risk factors of cardiovascular disease,2nd – patients with presence of these factors, 3rd – patients with atherosclerotic plaques in the carotid artery. All patients were examinedin complex: ultrasound of vessels measurement on the Aloka 5000 with IMT, evaluation of lipid profile, glucose level, determination of C-reactive protein (CRP in blood plasma and cytokines – tumor necrosis factor-α (TNF-α, interferon-γ (IFN-γ, interleukin (IL -1, -8, -4, specific antibody immunoglobulin G (IgG to cytomegalovirus (CMV, herpes simplex virus type 1 (HSV-1 , C. pneumoniae, H. pylori and β-hemolytic streptococci group A. Immune system status was assessed by innate and acquired immunity factors.Results. In groups of examined patients by increasing IMT of the common carotid artery infectious viruses (CMV, HSV-1 burden increased,what was obligatory for all groups. In the 3rd group, in 45 % of patients C. pneumoniae was found. In the 2nd and 3rd groups weakening ofacquired immunity was found out – reducing the total number of lymphocytes and T-lymphocytes, the increase of CRP and proinflammatory cytokines (IL-1, -8, IFN-γ, TNF-α, it was indicating development of inflammatory process, and in the third group it took characters of the system inflammatory response. In cluster analysis it was revealed that the process of thickening of the vascular wall is influenced by complex factors – infectious, metabolic and immune.Conclusion. The presence of the close relationship between the thickness of vessel walls and infectious, metabolic (lipid and

  13. Study of Individual Characteristic Abdominal Wall Thickness Based on Magnetic Anchored Surgical Instruments

    Directory of Open Access Journals (Sweden)

    Ding-Hui Dong

    2015-01-01

    Full Text Available Background: Magnetic anchored surgical instruments (MASI, relying on magnetic force, can break through the limitations of the single port approach in dexterity. Individual characteristic abdominal wall thickness (ICAWT deeply influences magnetic force that determines the safety of MASI. The purpose of this study was to research the abdominal wall characteristics in MASI applied environment to find ICAWT, and then construct an artful method to predict ICAWT, resulting in better safety and feasibility for MASI. Methods: For MASI, ICAWT is referred to the thickness of thickest point in the applied environment. We determined ICAWT through finding the thickest point in computed tomography scans. We also investigated the traits of abdominal wall thickness to discover the factor that can be used to predict ICAWT. Results: Abdominal wall at C point in the middle third lumbar vertebra plane (L3 is the thickest during chosen points. Fat layer thickness plays a more important role in abdominal wall thickness than muscle layer thickness. "BMI-ICAWT" curve was obtained based on abdominal wall thickness of C point in L3 plane, and the expression was as follow: f(x = P1 × x 2 + P2 × x + P3, where P1 = 0.03916 (0.01776, 0.06056, P2 = 1.098 (0.03197, 2.164, P3 = −18.52 (−31.64, −5.412, R-square: 0.99. Conclusions: Abdominal wall thickness of C point at L3 could be regarded as ICAWT. BMI could be a reliable predictor of ICAWT. In the light of "BMI-ICAWT" curve, we may conveniently predict ICAWT by BMI, resulting a better safety and feasibility for MASI.

  14. Method for Improving Transverse Wall Thickness Precision of Seamless Steel Tube Based on Tube Rotation

    Institute of Scientific and Technical Information of China (English)

    Yong-zheng JIANG; Hua-ping TANG

    2015-01-01

    The tube rotation method (TRM) refers to the rotational movement of steel tube about its axis as well as translation in rolling direction in stretch reducing rolling process. The inlfuence of the TRM on transverse wall thickness precision of seamless steel tube was studied. Thickness distribution of the TRM was obtained by superimposing the thickened amount of single pass roll-ing. Results show that the TRM can effectively improve the evenness of thickness distribution. In order to analyze the inlfuence mechanism of the TRM, the ifnite element method was adopted to simulate the thickness distribution in stretch reduction process. Results show that the TRM changes the roundtrip lfow between two ifx places of conventional stretch reducing and inhibits the directional accumulation of metal. In addition, the TRM has a correction effect on thickness cusp. All these advantages of the TRM help to improve the transverse wall thickness precision of seamless steel tube.

  15. Strength-toughness requirements for thick walled high pressure vessels

    International Nuclear Information System (INIS)

    The strength and toughness requirements of materials for use in high pressure vessels has been the subject of some discussion in the meetings of the Materials Task Group of the Special Working Group High Pressure Vessels. A fracture mechanics analysis has been performed to theoretically establish the required toughness for a high pressure vessel. This paper reports that the analysis performed is based on the validity requirement for plane strain fracture of fracture toughness test specimens. This is that at the fracture event, the crack length, uncracked ligament, and vessel length must each be greater than fifty times the crack tip plastic zone size for brittle fracture to occur. For high pressure piping applications, the limiting physical dimension is the uncracked ligament, as it can be assumed that the other dimensions are always greater than fifty times the crack tip plastic zone. To perform the fracture mechanics analysis several parameters must be known: these include vessel dimensions, material strength, degree of autofrettage, and design pressure. Results of the analysis show, remarkably, that the effects of radius ratio, pressure and degree of autofrettage can be ignored when establishing strength and toughness requirements for code purposes. The only parameters that enter into the calculation are yield strength, toughness and vessel thickness. The final results can easily be represented as a graph of yield strength against toughness on which several curves, one for each vessel thickness, are plotted

  16. Relation between plaque type, plaque thickness, blood shear stress, and plaque stress in coronary arteries assessed by X-ray Angiography and Intravascular Ultrasound

    OpenAIRE

    Balocco, Simone; Gatta, Carlo; Alberti, Marina; Carrillo, Xavier; Rigla, Juan; Radeva, Petia

    2012-01-01

    Purpose: Atheromatic plaque progression is affected, among others phenomena, by biomechanical, biochemical, and physiological factors. In this paper, the authors introduce a novel framework able to provide both morphological (vessel radius, plaque thickness, and type) and biomechanical (wall shear stress and Von Mises stress) indices of coronary arteries. Methods: First, the approach reconstructs the three-dimensional morphology of the vessel from intravascular ultrasound(IVUS) and Angiograph...

  17. Simultaneous measurement of sound velocity and wall thickness of a tube.

    Science.gov (United States)

    He, P

    2001-10-01

    A method for simultaneously measuring the sound propagation velocity and the thickness of each wall on the opposite sides of a tube is presented. The method uses a pair of ultrasound transducers to produce two reflected pulses from the outer and inner surfaces of the tube wall on the each side, and two transmitted pulses, one with and one without the tube sample between the two transducers. Using the time-domain analysis, sound velocity and wall thickness of the tube are determined from the time delays between the three pairs of ultrasound pulses, whereas using the frequency-domain analysis, phase velocity, group velocity, and wall thickness of the tube are determined from the phase differences between the three pairs of ultrasound pulses. Results of measurements on five tube samples are reported. PMID:11775655

  18. Smoking status and common carotid artery intima-medial thickness among middle-aged men and women based on ultrasound measurement: a cohort study

    OpenAIRE

    Merz C Noel; Paul-Labrador Maura; Fan Amy Z; Iribarren Carlos; Dwyer James H

    2006-01-01

    Abstract Background Cigarette smoking is an established causal factor for atherosclerosis. However, the smoking effect on different echogenic components of carotid arterial wall measured by ultrasound is not well elucidated. Methods Middle-aged men and women who had IMT measurement ≥ 0.7 mm at baseline and follow-up were included (N = 413, age 40–60 years at baseline in 1995). Intima-media thickness of common carotid artery (CCA-IMT) and its components (echogenic and echolucent layers) were m...

  19. Ultrasonic Estimation of Mechanical Properties of Pulmonary Arterial Wall Under Normoxic and Hypoxic Conditions

    Science.gov (United States)

    Waters, Kendall R.; Mukdadi, Osama M.

    2005-04-01

    Secondary pediatric pulmonary hypertension is a disease that could benefit from improved ultrasonic diagnostic techniques. We perform high-frequency in vitro ultrasound measurements (25 MHz to 100 MHz) on fresh and fixed pulmonary arterial walls excised from normoxic and hypoxic Long-Evans rat models. Estimates of the elastic stiffness coefficients are determined from measurements of the speed of sound. Preliminary results indicate that hypoxia leads to up to increase of 20 % in stiffening of the pulmonary arterial wall.

  20. Cine magnetic resonance imaging in hypertrophic cardiomyopathy. Evaluation of left ventricular wall thickness and systolic function

    International Nuclear Information System (INIS)

    Cine magnetic resonance imaging (MRI) was performed on 21 patients with hypertrophic cardiomyopathy and left ventricular (LV) regional systolic function was quantitatively evaluated. The visual evaluation of hypertrophic regions and the motion patterns of their walls on cine MR images was possible in most cases. However, this evaluation was subjective and a quantitative analysis was difficult. Septal and posterior wall thickness measured on cine MRI correlated well with those obtained by ultrasound cardiogram (UCG). There was also a good correlation between % thickness of LV wall and its thickness at end diastolic phase. Comparison of % thickness between normal subjects and hypertrophic cardiomyopathies showed a tendency of it being less at the region of more severe hypertrophic change. We conclude that cine MRI is a useful means to analyse the anatomical feature and functional change in hypertrophic cardiomyopathy. (author)

  1. In-service inspections of thick walled concrete structures

    International Nuclear Information System (INIS)

    Ageing management and renewal of the operating license of existing NPP's are at present the main problems of nuclear energy. For the ageing management of concrete structures the OECD-Nuclear Energy Agency, Committee on the Safety on Nuclear Installations defined as the first priority ISI technigues for reinforced concrete structures having thick sections and areas not directly accessible for inspections. In this paper is described the NRI Rez research and development programme in this field. Three ISI techniques were selected: Impact-Echo ultrasound and high frequency radar or betatron 7 MeV. In the period from 2004 to 2005 the mathematical studies of efficiency of Impact-Echo method for detecting of reinforcing bars, deep surface cracks and internal voids were done. In 2005 will be manufactured the 2 × 2 × 1 m concrete specimens with reinforcing bars, crack and holes which represent possible defects. Results of the solution will be used for qualification of ISI techniques

  2. [The age-specific changes in the wall of the arterial circle of Willis].

    Science.gov (United States)

    Trushel', N A; Pivchenko, P G; Bel'chikov, E I

    2013-01-01

    The objective of the present study was to create the database of morphometric and morphological characteristics of the wall of the vessels of the Willis arterial circle at the site of their bifurcation throughout the period of postnatal ontogenesis in man to be used for the postmortem determination of human age. Preparations of vascular cross sections were used to measure the intima thickness (intimal pads) in the region of lateral bifurcation angles on the terminal branch of the internal carotid and basilar arteries obtained from 130 corpses of the subjects aged between 0 and 75 years. The histological preparations were stained with hematoxylin/eosin and van Gieson's pyrofuchsin or by the Unnar-Tenzer method. Morphometry was performed using a Bioscan image analyser and the Scion Image v.402 software. The Microsoft Excel 2003 package was used for the primary treatment of the data obtained. They were used to draw the table of intimal pads developing throughout the period of postnatal ontogenesis in man that allows for the postmortem determination of approximate human age. The study showed that the thickening of intimal pads and concomitant thinning of the underlying muscular layer during the postnatal ontogenesis should be regarded as being normal age-related changes. PMID:23802302

  3. Association of carotid artery intima-media thickness and cardiovascular risk factors in adult

    International Nuclear Information System (INIS)

    Increased intima-media thickness (IMT) of the common carotid artery is an early marker of atherosclerosis and a powerful predictor of coronary and cerebrovascular diseases. The purpose of this study was to evaluate the correlation between carotid artery IMT and cardiovascular risk factors. Total 134 adult were performed with Ultrasonography to measure IMT at common carotid artery, the physical measurements and blood tests, the following results were obtained. As a result, IMT showed higher value in male IMT than female IMT. And, the IMT increased according to the age increased. Also, TC and AI have positive significant correlation with IMT. In Conclusion, cardiovascular risk factors with adult are associated with increased IMT of common carotid artery

  4. Association of carotid artery intima-media thickness and cardiovascular risk factors in adult

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Mi Young [Dept. of Diagnostic Radiology, Dankook University Hospital, Cheonan (Korea, Republic of); Kim, Hwa Sun [Dept. of Radiological Technology, Ansan University, Ansan (Korea, Republic of); Kim, Shin Young [Dept. of Anatomy and Cell Biology, School of Medicine, Hanyang University, Seoul (Korea, Republic of)

    2013-03-15

    Increased intima-media thickness (IMT) of the common carotid artery is an early marker of atherosclerosis and a powerful predictor of coronary and cerebrovascular diseases. The purpose of this study was to evaluate the correlation between carotid artery IMT and cardiovascular risk factors. Total 134 adult were performed with Ultrasonography to measure IMT at common carotid artery, the physical measurements and blood tests, the following results were obtained. As a result, IMT showed higher value in male IMT than female IMT. And, the IMT increased according to the age increased. Also, TC and AI have positive significant correlation with IMT. In Conclusion, cardiovascular risk factors with adult are associated with increased IMT of common carotid artery.

  5. Wall Thickness Measurement Of Insulated Pipe By Tangential Radiography Technique Using Ir 192

    International Nuclear Information System (INIS)

    Insulation pipe wall thickness by tangential radiography technique has been carried out using 41 Curie Iridium 192 source has activity for two carbon steel pipes. The outer diameter of the first pipe is 90 mm, wall thickness is 75.0 mm, source film film distance is 609.5 mm, source tangential point of insulation is 489.5 mm and exposure time 3 minute and 25 second. From the calculation, the first pipe thickness is found to be 12.54 mm and for the second pipe is 8.42 mm. The thickness is due to inaccuracy in reading the pipe thickness on radiography film and the geometry distortion radiation path

  6. Non-invasive Ultrasonic Measurements of Small Mechanical Alterations in Sub-millimeter Walls of Arteries and Phantoms

    Science.gov (United States)

    Brum, J.; Ramos, A.; Bazan, I.; Negreira, C.; Ramirez, A.; Diez, L.

    The detection of changes in the properties of the walls in blood vessels (e.g. modifications in thickness or elasticity) is a promising way for the early diagnosis of cardiovascular diseases (e.g. atherosclerosis), and some attempts have been made using classic ultrasonic images. However, to obtain a reliable non-invasive estimation of these changes still presents many challenges that must be overcome, in particular, to achieve an accurate estimation of the vessel wall thickness, which usually is associated to strain and elasticity alterations happening before the cardiovascular disease presents clinical symptom; to solve efficiently these aspects is a very difficult task. In this work, the application to vessels of a recent ultrasonic method developed by the authors for estimating wall thicknesses is described. This method (based on high-resolution power spectral density - PSD) and its algorithmic responses were tested on an arterial phantom under physiological conditions of flow and pressure, and some results are compared to those obtained using a direct-time thickness estimation and with the resolutions related to our alternative cross-correlation option shown in previous papers. A higher spatial resolution is obtained, for experimental multi-pulse ultrasonic echoes, with this PSD method in comparison to those based on conventional echography, cross correlation operators or other spectral options.

  7. Pipe Wall Thickness Monitoring Using Dry-Coupled Ultrasonic Waveguide Technique

    International Nuclear Information System (INIS)

    In order to monitor a corrosion or FAC (Flow Accelerated Corrosion) in a pipe, there is a need to measure pipe wall thickness at high temperature. Ultrasonic thickness gauging is the most commonly used non-destructive testing technique for wall thickness measurement. However, current commonly available ultrasonic transducers cannot withstand high temperatures, such as above 200 .deg. C. It is therefore necessary to carry out manual measurements during plant shutdowns. The current method thus reveals several disadvantages: inspection have to be performed during shutdowns with the possible consequences of prolonging down time and increasing production losses, insulation has to be removed and replaced for each manual measurement, and scaffolding has to be installed to inaccessible areas, resulting in considerable cost for interventions. It has been suggested that a structural health monitoring approach with permanently installed ultrasonic thickness gauges could have substantial benefits over current practices. The main reasons why conventional piezoelectric ultrasonic transducers cannot be used at high temperatures are that the piezo-ceramic becomes depolarized at temperature above the Curie temperature and because differential thermal expansion of the substrate, couplant, and piezoelectric materials cause failure. In this paper, a shear horizontal waveguide technique for wall thickness monitoring at high temperature is investigated. Two different designs for contact to strip waveguide are shown and the quality of output signal is compared and reviewed. After a success of acquiring high quality ultrasonic signal, experiment on the wall thickness monitoring at high temperature is planned

  8. Dependence of Thermal Conductivity on Thickness in Single-Walled Carbon Nanotube Films.

    Science.gov (United States)

    Lee, Kyung-Min; Shrestha, Ramesh; Dangol, Ashesh; Chang, Won Seok; Coker, Zachary; Choi, Tae-Youl

    2016-01-01

    Herein, we report experimentally dependence of thermal conductivity on thickness of single walled carbon nanotubes (SWNTs) thin films; the measurements are based on the micropipette thermal sensor technique. Accurate and well resolved measurements of thermal conductivity made by the micropipette sensor showed a correlated behavior of thickness and thermal conductivity of CNT films that thermal conductivity decreased as thickness increased. The thickness dependence is explained by reduction of mean free path (MFP), which is induced by more intertubular junctions in more dense-packed carbon nanotube (CNT) networks; the thicker SWCNT films were revealed to have higher density. PMID:27398564

  9. Airway wall thickness assessment: a new functionality in virtual bronchoscopy investigation

    Science.gov (United States)

    Saragaglia, A.; Fetita, C.; Brillet, P. Y.; Prêteux, F.; Grenier, P. A.

    2007-03-01

    While classic virtual bronchoscopy offers visualization facilities for investigating the shape of the inner airway wall surface, it provides no information regarding the local thickness of the wall. Such information may be crucial for evaluating the severity of remodeling of the bronchial wall in asthma and to guide bronchial biopsies for staging of lung cancers. This paper develops a new functionality with the virtual bronchoscopy, allowing to estimate and map the information of the bronchus wall thickness on the lumen wall surface, and to display it as coded colors during endoluminal navigation. The local bronchus wall thickness estimation relies on a new automated 3D segmentation approach using strong 3D morphological filtering and model-fitting. Such an approach reconstructs the inner/outer airway wall surfaces from multi-detector CT data as follows. First, the airway lumen is segmented and its surface geometry reconstructed using either a restricted Delaunay or a Marching Cubes based triangulation approach. The lumen mesh is then locally deformed in the surface normal direction under specific force constraints which stabilize the model evolution at the level of the outer bronchus wall surface. The developed segmentation approach was validated with respect to both 3D mathematicallysimulated image phantoms of bronchus-vessel subdivisions and to state-of-the-art cross-section area estimation techniques when applied to clinical data. The investigation in virtual bronchoscopy mode is further enhanced by encoding the local wall thickness at each vertex of the lumen surface mesh and displaying it during navigation, according to a specific color map.

  10. Determination of wall tension in cerebral artery aneurysms by numerical simulation

    DEFF Research Database (Denmark)

    Isaksen, J.G.; Bazilevs, Y.; Kvamsdal, T.; Zhang, Y.; Kaspersen, J.H.; Waterloo, K.; Ingebrigtsen, T.; Rommer, Bertil Roland

    2008-01-01

    BACKGROUND AND PURPOSE: Cerebral artery aneurysms rupture when wall tension exceeds the strength of the wall tissue. At present, risk-assessment of unruptured aneurysms does not include evaluation of the lesions shape, yet clinical experience suggests that this is of importance. We aimed to devel...

  11. Correlation between coronary artery disease severity, left ventricular mass index and carotid intima media thickness, assessed by radio-frequency

    Directory of Open Access Journals (Sweden)

    Ciccone Marco M

    2011-11-01

    Full Text Available Abstract Background Intima-media thickness of the common carotid artery (CCA-IMT is a validated marker of systemic atherosclerosis process. The aim of this study was to evaluate the association between coronary artery disease (CAD, left ventricular hypertrophy (LVH and CCA-IMT, assessed by Radio Frequency-Quality Intima Media Thickness (RFQIMT method, the next generation of IMT real-time measurement, based on the direct analysis of the radiofrequency signal and endowed with high accuracy and reproducibility in early detection of arterial wall thickness. Methods 115 patients (76 men, mean age: 65.1 ± 12 years referred to our department and shown significant (≥ 70% luminal obstruction stenosis at least in one major epicardial coronary artery were studied. Coronary angiograms were divided for severity and extent of the disease: 79 patients (69% had one, 24 patients (21% two, 12 patients (10% three major epicardial coronary arteries with ≥ 70% stenosis. All patients underwent echocardiography and carotid ultrasound examination, assessed by RF. Results Dividing RFQIMT data in tertiles, dyslipidaemia (31 patients with IMT ≥ 1.20 mm vs 16 with IMT = 0.91-1.19 vs 25 with IMT ≤ 0.9, p = 0.004, LVMI (153.5 ± 20.6 g/m2 in IMT ≥ 1.20 mm vs 131.2 ± 8.4 g/m2 in IMT = 0.91-1.19 mm vs 114.3 ± 11.1 g/m2 in IMT ≤ 0.9 mm, P 2 = 0.88, RFQIMT remained significantly associated with the dyslipidemia (regression coefficient ± standard error [SE]: 0.057 ± 0.023; p = 0.017, LVMI (regression coefficient ± SE: 0.01 ± 0.001; P Conclusions RFQIMT is a sophisticated method for carotid ultrasound evaluation. Its evaluation in patients with at least one important major epicardial coronary vessel stenosis would help the accuracy in the general assessment of the number of coronary lesions in these patients.

  12. Quantification of pulmonary arterial wall distensibility using parameters extracted from volumetric micro-CT images

    Science.gov (United States)

    Johnson, Roger H.; Karau, Kelly L.; Molthen, Robert C.; Dawson, Christopher A.

    1999-09-01

    Stiffening, or loss of distensibility, of arterial vessel walls is among the manifestations of a number of vascular diseases including pulmonary arterial hypertension. We are attempting to quantify the mechanical properties of vessel walls of the pulmonary arterial tree using parameters derived from high-resolution volumetric x-ray CT images of rat lungs. The pulmonary arterial trees of the excised lungs are filled with a contrast agent. The lungs are imaged with arterial pressures spanning the physiological range. Vessel segment diameters are measured from the inlet to the periphery, and distensibilities calculated from diameters as a function of pressure. The method shows promise as an adjunct to other morphometric techniques such as histology and corrosion casting. It possesses the advantages of being nondestructive, characterizing the vascular structures while the lungs are imaged rapidly and in a near-physiological state, and providing the ability to associate mechanical properties with vessel location in the intact tree hierarchy.

  13. Wall Shear Stress Prediction Using Computational Simulation on Patient Specific Artery with Aneurysm

    Directory of Open Access Journals (Sweden)

    Yunus Muhamad

    2014-07-01

    Full Text Available An aneurysm is formed when a blood vessel becomes dilated or distorted. It will cause the vessel to expand to a size greater than its original diameter. In this study, Wall Shear Stress (WSS of cerebral artery with aneurysm was predicted using Computational Fluid Dynamics (CFD. WSS in the artery is one of the indicators for brain artery disease progression. Based on the results, the maximum value of blood velocity and WSS on patient specific artery with aneurysm are 3.23 m/s and 60.1 Pa, respectively. The location of high WSS is before and after the aneurysm bulge. The WSS is above the normal physiological value where the artery wall is exposed to high stress. Hence, the vessel at this location is anticipated to become weaker and could be further dilated.

  14. New radioisotope method for non-contact gauging of the wall thickness of steel tubes

    International Nuclear Information System (INIS)

    A new method for non-contact gauging of the wall thickness of steel tubes with radioactive isotopes is described. The tube is irradiated perpendicularly to its axis and the system source-detector is continuously moved perpendicularly to the radiation beam. The applicability of the method has been demonstrated in laboratory tests with 60Co and tubes of different outside diameter and of various wall thickness. The agreement with the theoretical absorption curves is excellent. Accuracy of the measurement is better than 3%. Using a 100 Ci 60Co source, this accuracy is achievable at a wall thickness between about 22 mm for tubes of 200 mm outer diameter and 6 mm for 700 mm tubes. The proposed sequence of operations is described. One examination takes between 10 and 20 s, depending on the dimensions of the tube. (author)

  15. On the effect of heating wall thickness on pool boiling burnout

    International Nuclear Information System (INIS)

    The effect of the thermal properties of thin heating wall on the range of values of thickness influencing burnout heat flux was studied. Brief details are given of the experiment performed with thin metal layers of Cu, Ni, Sn, and Zn in distilled, degassed and saturated water at atmospheric pressure. The results show that over a range of values the heater thickness appreciably affects burnout. When, however, a 'limiting value', specific to each of the metals, is exceeded the influence of wall thickness becomes negligible. Under the conditions, described, the limiting values, defined to correspond to the ratio, burnout heat flux/asymptotic heat flux = 0.9, depends upon the parameter √(k p c) of the heating wall where k, p, and c are thermal conductivity, density, and specific heat. (U.K.)

  16. Conjugate mixed convection in the entrance region of a symmetrically heated vertical channel with thick walls

    International Nuclear Information System (INIS)

    Conjugate mixed convection with buoyancy assisted laminar flow in the entrance region of a vertical channel is considered numerically. The problem is solved by a finite volume method for a thick walled, two-regional channel which has constant and uniform outside wall temperatures. The effects of wall thermal conduction as well as assisted buoyancy force on the flow and heat transfer are discussed in detail. Results are presented for a Prandtl number of 0.7, solid-to-fluid thermal conductivity ratios of 1≤ k* < ∞, wall thickness-to-channel length ratios of 0≤ l* ≤5, Reynolds numbers of 200≤ Re ≤1000, and for various Grashof numbers. The critical buoyancy parameter (Gr/Re), above which the flow reversal occurs, increases linearly with the increasing l*/k*, while it is independent on the Reynolds number. (authors)

  17. CARDIAC TRANSPLANT REJECTION AND NON-INVASIVE COMON CAROTID ARTERY WALL FUNCTIONAL INDICES

    OpenAIRE

    A. O. Shevchenko; I. U. Tunjaieva; A. A. Nasyrova; B. L. Mironkov; I. M. Ilinsky; N. P. Mozhejko; I. I. Muminov; O. P. Shevchenko

    2015-01-01

    Allograft rejection would entail an increase in certain blood biomarkers and active substances derived from activated inflammatory cells which could influence entire vascular endothelial function and deteriorate arterial wall stiffness. We propose that carotid wall functional indices measured with non-invasive ultrasound could we valuable markers of the subclinical cardiac allograft rejection. Aim. Our goal was to analyze the clinical utility of functional common carotid wall (CCW) variables ...

  18. MR imaging of the arterial wall in normal volunteers and arteriosclerotic patients

    International Nuclear Information System (INIS)

    MR angiography is based on the signal characteristics of flowing blood, whereas the arterial wall is not delineated. Its visualization requires maximal spatial resolution and reliable compensation for moving spins. Presaturation and rephasing gradients were applied to spin-echo and fast low-angle shot (FLASH) sequences combined with a reduction of the field of view to approximately 10 cm. Three-dimensional FLASH sequences demonstrated spin saturation within the imaging volume without additional radio-frequency pulses and was sensitive to alterations in the arterial wall. CHESS techniques (fat sensitive) suppressed signal from the normal arterial wall. Small fatty or sclerotic deposits in the femoral, popliteal, and carotid walls were detected prior to marked stenosis

  19. Colonic wall thickness measured by ultrasound: striking differences in patients with cystic fibrosis versus healthy controls.

    OpenAIRE

    Haber, H P; Benda, N; Fitzke, G; Lang, A.; Langenberg, M; Riethmüller, J; Stern, M.

    1997-01-01

    BACKGROUND: Colonic strictures represent an advanced stage of fibrosing colonopathy in patients with cystic fibrosis. AIMS: To clarify whether ultrasonography can identify patients with an early stage of fibrosing colonopathy and to determine clinical factors that influence bowel wall thickening. PATIENTS: Ninety patients with cystic fibrosis, median age 10 years, and 46 healthy controls, median age 13 years, were investigated. METHODS: Bowel wall thickness was measured by ultrasound in a pro...

  20. The welding technique of thick-walled stainless steel pipes in Qinshan Ii expansion project

    International Nuclear Information System (INIS)

    The paper introduces the welding techniques of thick-walled stainless steel pipes in Qinshan II Expansion Project, which also analyses the main factors affected the weld quality in installation process, and introduces the control methods in preparation period before welding, welding products as well as welding distortion and welding stress. The article proposes solutions to quality problems of welding deformation, dislocating distortion, and lack of groove uniformity. By adopting rational welding sequence, witness point management technique, welding simulation technique, and stress distribution promotion by local patching, the welding quality can be warranted, so as to promote the development of thick-walled pipe welding technique. (authors)

  1. Determination of the chest wall thickness as calibration parameter for dosimetric partial-body counting

    International Nuclear Information System (INIS)

    The authors describe actual partial body measurements with Phoswich detectors in the in-vivo laboratory of the Institute for Technology in Karlsruhe. The chest wall thickness is estimated from the radio of body weight to body length. This formula includes several uncertainties. The aim of the project was the reduction of the uncertainties of the empirical formula using ultrasonography. This method allows an accuracy of plus or minus 1.1 mm for the determined chest wall thickness. Besides the experimental study several voxel models were used to determine the efficiency of modeled measuring systems. The voxel models reach the same accuracy as the ultrasound method.

  2. Automatic plaque characterization and vessel wall segmentation in magnetic resonance images of atherosclerotic carotid arteries

    Science.gov (United States)

    Adame, Isabel M.; van der Geest, Rob J.; Wasserman, Bruce A.; Mohamed, Mona; Reiber, Johan H. C.; Lelieveldt, Boudewijn P. F.

    2004-05-01

    Composition and structure of atherosclerotic plaque is a primary focus of cardiovascular research. In vivo MRI provides a meanse to non-invasively image and assess the morphological features of athersclerotic and normal human carotid arteries. To quantitatively assess the vulnerability and the type of plaque, the contours of the lumen, outer boundary of the vessel wall and plaque components, need to be traced. To achieve this goal, we have developed an automated contou detection technique, which consists of three consecutive steps: firstly, the outer boundary of the vessel wall is detected by means of an ellipse-fitting procedure in order to obtain smoothed shapes; secondly, the lumen is segnented using fuzzy clustering. Thre region to be classified is that within the outer vessel wall boundary obtained from the previous step; finally, for plaque detection we follow the same approach as for lumen segmentation: fuzzy clustering. However, plaque is more difficult to segment, as the pixel gray value can differ considerably from one region to another, even when it corresponds to the same type of tissue. That makes further processing necessary. All these three steps might be carried out combining information from different sequences (PD-, T2-, T1-weighted images, pre- and post-contrast), to improve the contour detection. The algorithm has been validated in vivo on 58 high-resolution PD and T1 weighted MR images (19 patients). The results demonstrate excellent correspondence between automatic and manual area measurements: lumen (r=0.94), outer (r=0.92), and acceptable for fibrous cap thickness (r=0.76).

  3. An exact solution for a thick domain wall in general relativity

    Science.gov (United States)

    Goetz, Guenter; Noetzold, Dirk

    1989-01-01

    An exact solution of the Einstein equations for a static, planar domain wall with finite thickness is presented. At infinity, density and pressure vanish and the space-time tends to the Minkowski vacuum on one side of the wall and to the Taub vacuum on the other side. A surprising feature of this solution is that the density and pressure distribution are symmetric about the central plane of the wall whereas the space-time metric and therefore also the gravitational field experienced by a test particle is asymmetric.

  4. Lateral abdominal wall hematoma as a rare complication after carotid artery stenting: a case report

    Directory of Open Access Journals (Sweden)

    Satomi Jyunichiro

    2009-11-01

    Full Text Available Abstract Abdominal wall hematoma is a rare and life-threatening complication after carotid artery stenting (CAS, but it can occur when activated clotting time is prolonged. We report a right lateral abdominal wall hematoma caused by rupture of the superficial circumflex iliac artery after CAS in a 72-year-old man with severe stenosis of the origin of the right internal carotid artery. We performed CAS for the targeted lesion while activated clotting time exceeded 300 seconds. After 2 hours, he complained of right lateral abdominal pain. Abdominal computed tomography revealed an extensive hematoma in the right lateral abdominal wall. Activated clotting time was 180 seconds at this point. Seven hours later, he developed hypotension and hemoglobin level dropped to 11.3 g/dl. Subsequent computed tomography showed enlargement of the hematoma. Emergent selective angiography of the external iliac artery revealed active bleeding from the right superficial circumflex iliac artery. Transcatheter arterial embolization with Gelfoam and microcoils was performed successfully. With more CAS procedures being performed, it is important for endovascular surgeons and radiologists to consider the possibility of abdominal wall hematoma in this situation.

  5. Thermal Marangoni instability of a thin film flowing down a thick wall deformed in the backside

    Science.gov (United States)

    Dávalos-Orozco, L. A.

    2016-05-01

    The nonlinear instability of a thin liquid film flowing down a heated thick wall with deformations in the backside is investigated. Here it is assumed that the wall deformations are sinusoidal in space. Time dependent perturbations are imposed at the origin of the free surface of the film. It is found that the wall deformations have an important influence on the flow instability. Moreover, it is shown that the free surface has a large amplitude spatial response to the backside deformations of the wall. This response increases its amplitude considerably when decreasing the wall spatial wavelength down to the wavelength of the time dependent perturbations. At that point, numerical analysis reveals that the time dependent perturbations in some cases are almost impossible to observe on the free surface response. However, in other cases, their interaction produces large amplitude nonlinear wave modulations.

  6. Artery buckling analysis using a two-layered wall model with collagen dispersion.

    Science.gov (United States)

    Mottahedi, Mohammad; Han, Hai-Chao

    2016-07-01

    Artery buckling has been proposed as a possible cause for artery tortuosity associated with various vascular diseases. Since microstructure of arterial wall changes with aging and diseases, it is essential to establish the relationship between microscopic wall structure and artery buckling behavior. The objective of this study was to developed arterial buckling equations to incorporate the two-layered wall structure with dispersed collagen fiber distribution. Seven porcine carotid arteries were tested for buckling to determine their critical buckling pressures at different axial stretch ratios. The mechanical properties of these intact arteries and their intima-media layer were determined via pressurized inflation test. Collagen alignment was measured from histological sections and modeled by a modified von-Mises distribution. Buckling equations were developed accordingly using microstructure-motivated strain energy function. Our results demonstrated that collagen fibers disperse around two mean orientations symmetrically to the circumferential direction (39.02°±3.04°) in the adventitia layer; while aligning closely in the circumferential direction (2.06°±3.88°) in the media layer. The microstructure based two-layered model with collagen fiber dispersion described the buckling behavior of arteries well with the model predicted critical pressures match well with the experimental measurement. Parametric studies showed that with increasing fiber dispersion parameter, the predicted critical buckling pressure increases. These results validate the microstructure-based model equations for artery buckling and set a base for further studies to predict the stability of arteries due to microstructural changes associated with vascular diseases and aging. PMID:27031686

  7. Common carotid artery intima-media thickness, carotid plaques, and walking speed.

    OpenAIRE

    Elbaz, Alexis; Ripert, Mahaut; Tavernier, Béatrice; Février, Benoît; Zureik, Mahmoud; Gariépy, Jérôme; Alpérovitch, Annick; Tzourio, Christophe

    2005-01-01

    BACKGROUND AND PURPOSE: Gait dysfunction is an important cause of disability among the elderly and may be, in part, of vascular origin. We studied the association between carotid ultrasound parameters and measures of gait and balance in subjects 65 to 85 years of age who participated in the baseline phase of the Three-City Study in the Dijon center. METHODS: The study population comprised 2572 noninstitutionalized individuals. Carotid plaques and common carotid artery intima-media thickness (...

  8. Association Between Epicardial Fat Thickness and Premature Coronary Artery Disease: A Case Control Study

    OpenAIRE

    Faghihi, Shadi; Vasheghani-Farahani, Ali; Parsaee, Mozhgan; Saedi, Sedigheh; Ghadrdoost, Behshid

    2015-01-01

    Background: The association between epicardial fat thickness (EFT) and premature coronary artery disease (CAD) has not been elaborately studied. Objectives: In the present study, we sought whether such a relationship between EFT and CAD exists. Patients and Methods: Sixty two consecutive subjects, under 50 years of age, who underwent coronary angiography (CAG) with the aspect of CAD, were included in this case control study. They were divided into two groups of 31 subjects, namely CAD (cases)...

  9. A discrete mesoscopic particle model of the mechanics of a multi-constituent arterial wall.

    Science.gov (United States)

    Witthoft, Alexandra; Yazdani, Alireza; Peng, Zhangli; Bellini, Chiara; Humphrey, Jay D; Karniadakis, George Em

    2016-01-01

    Blood vessels have unique properties that allow them to function together within a complex, self-regulating network. The contractile capacity of the wall combined with complex mechanical properties of the extracellular matrix enables vessels to adapt to changes in haemodynamic loading. Homogenized phenomenological and multi-constituent, structurally motivated continuum models have successfully captured these mechanical properties, but truly describing intricate microstructural details of the arterial wall may require a discrete framework. Such an approach would facilitate modelling interactions between or the separation of layers of the wall and would offer the advantage of seamless integration with discrete models of complex blood flow. We present a discrete particle model of a multi-constituent, nonlinearly elastic, anisotropic arterial wall, which we develop using the dissipative particle dynamics method. Mimicking basic features of the microstructure of the arterial wall, the model comprises an elastin matrix having isotropic nonlinear elastic properties plus anisotropic fibre reinforcement that represents the stiffer collagen fibres of the wall. These collagen fibres are distributed evenly and are oriented in four directions, symmetric to the vessel axis. Experimental results from biaxial mechanical tests of an artery are used for model validation, and a delamination test is simulated to demonstrate the new capabilities of the model. PMID:26790998

  10. Wall-Thickness Dependence of Cooling-Induced Deformation of Polystyrene Spherical Shells

    International Nuclear Information System (INIS)

    Experiments on the wall-thickness dependence of the cooling-induced deformation (CID) of polystyrene (PS) spherical shells were carried out. For the experiments, the PS shells were fabricated by the density-matched emulsion method using the hand-shaken microencapsulation technique. The number-averaged and weight-averaged molecular weights of the PS were Mn 1.1 x 105 and Mw = 4.0 x 105, respectively. The diameter of the PS shells was ∼400-550 μm. To investigate the wall-thickness dependence of the CID, the wall thickness of the PS shells was varied between 5 and 60 μm. In the experiments, the PS shells were cooled by using liquid nitrogen, and their images were captured at 0 and -190 deg. C. For the investigation of the CID, two shapes of each shell that were measured at 0 and -190 deg. C were compared. The thinner PS shells showed larger CID. The maximum deformation was almost 1% of the outer radius when the shell aspect ratio (outer radius)/(wall thickness) was higher than 20. The repeatability of the CID was studied, and the results implied that residual stress in the PS shells had an influence on the CID

  11. Magnet Fall inside a Conductive Pipe: Motion and the Role of the Pipe Wall Thickness

    Science.gov (United States)

    Donoso, G.; Ladera, C. L.; Martin, P.

    2009-01-01

    Theoretical models and experimental results are presented for the retarded fall of a strong magnet inside a vertical conductive non-magnetic tube. Predictions and experimental results are in good agreement modelling the magnet as a simple magnetic dipole. The effect of varying the pipe wall thickness on the retarding magnetic drag is studied for…

  12. The influence of the composite casting wall thickness on the arrangement of particulate within the matrix

    Directory of Open Access Journals (Sweden)

    Z. Konopka

    2008-07-01

    Full Text Available The work presents the investigation results concerning the structure of composite pressure die castings with AlSi13Cu2 alloy matrix reinforced with SiC particles. The arrangement of the reinforcing particles within the matrix has been qualitatively assessed in specimens cut out of the castings of diverse wall thickness. Various pressure die castings have been used for the assessment, e. g. the castability test specimens with the wall thickness changed continuously from 3 mm to 0.2 mm. Examination has been held for composites containing various fractions of SiC particles, i.e. 10, 20, or 30 volume percent. An increase in uniformity of arrangement of SiC particles within the matrix accompanying the increase in the reinforcement fraction in composite volume has been observed. No differences caused by changes in casting wall thickness have been found in the reinforcement arrangement. Composites containing over 20 and 30 volume percent of SiC particles exhibit almost ideally uniform reinforcement arrangement. The uniform arrangement of reinforcing particles has been observed even for a casting of wall thickness equal to 0.2 mm.

  13. Automatic Thickness and Volume Estimation of Sprayed Concrete on Anchored Retaining Walls from Terrestrial LIDAR Data

    Science.gov (United States)

    Martínez-Sánchez, J.; Puente, I.; GonzálezJorge, H.; Riveiro, B.; Arias, P.

    2016-06-01

    When ground conditions are weak, particularly in free formed tunnel linings or retaining walls, sprayed concrete can be applied on the exposed surfaces immediately after excavation for shotcreting rock outcrops. In these situations, shotcrete is normally applied conjointly with rock bolts and mesh, thereby supporting the loose material that causes many of the small ground falls. On the other hand, contractors want to determine the thickness and volume of sprayed concrete for both technical and economic reasons: to guarantee their structural strength but also, to not deliver excess material that they will not be paid for. In this paper, we first introduce a terrestrial LiDAR-based method for the automatic detection of rock bolts, as typically used in anchored retaining walls. These ground support elements are segmented based on their geometry and they will serve as control points for the co-registration of two successive scans, before and after shotcreting. Then we compare both point clouds to estimate the sprayed concrete thickness and the expending volume on the wall. This novel methodology is demonstrated on repeated scan data from a retaining wall in the city of Vigo (Spain), resulting in a rock bolts detection rate of 91%, that permits to obtain a detailed information of the thickness and calculate a total volume of 3597 litres of concrete. These results have verified the effectiveness of the developed approach by increasing productivity and improving previous empirical proposals for real time thickness estimation.

  14. Quantitative CT: Associations between Emphysema, Airway Wall Thickness and Body Composition in COPD

    DEFF Research Database (Denmark)

    Rutten, Erica P A; Grydeland, Thomas B; Pillai, Sreekumar G;

    2011-01-01

    , CT scans were performed to determine emphysema (%LAA), airway wall thickness (AWT-Pi10), and lung mass. Muscle wasting based on FFMI was assessed by bioelectrical impedance. In both the men and women with COPD, FFMI was negatively associated with %LAA. FMI was positively associated with AWT-Pi10 in...

  15. Discrimination of Cylinders with Different Wall Thicknesses using Neural Networks and Simulated Dolphin Sonar Signals

    DEFF Research Database (Denmark)

    Andersen, Lars Nonboe; Au, Whitlow; Larsen, Jan;

    1999-01-01

    This paper describes a method integrating neural networks into a system for recognizing underwater objects. The system is based on a combination of simulated dolphin sonar signals, simulated auditory filters and artificial neural networks. The system is tested on a cylinder wall thickness...

  16. Chest Wall Thickness Measurements and the Dosimetric Implications for Male Radiation Workers at the KAERI

    International Nuclear Information System (INIS)

    Using ultrasound techniques, the Korea Atomic Energy Research Institute has measured chest wall thicknesses of a group of male workers at the Korea Atomic Energy Research Institute. A site-specific biometric equation has been developed for these workers. Chest wall thickness is an important modifier on lung counting efficiency. These data have been put into the perspective of the ICRP recommended dose limits for occupationally exposed workers:100 mSv in a 5-year period with a maximum of 50 mSv in any one year. For measured chest wall thicknesses of 1.9 cm to 4.1 cm and a 30 min counting time, the achievable MDAs for natural uranium in the KAERI lung counter vary from 5.75 mg to 11.28 mg. These values are close to, or even exceed, the predicted amounts of natural uranium that will remain in the lung (absorption type M and S) after an intake equal to the Annual Limit on Intake corresponding to a committed dose of 20 mSv. This paper shows that the KAERI lung counter probably cannot detect an intake of Type S natural uranium in a worker with a chest wall thickness equal to the average value (2.7 cm) under routine counting conditions

  17. Evaluation for Sequential Changes on Gallbladder Volume and Wall Thickness in Normal Young Adults

    International Nuclear Information System (INIS)

    This study examined 40 healthy volunteers had been tested for their gallbladder (GB) volume and wall thickness by a real time ultrasonography before and after a meal. The results are as follows : 1. The mean values of GB volume were 47.40. (SD 9.05) for male, 35.72. (SD 8.30) for female. 2. The mean value of wall thickness of GB was 2.3 mm (SD 0.3, male, SD 0.5, female). 3. The mean ejection-fraction rates of GB result in 67.20% for male, 63.95% for female. 4. The values of GB volume had significant negative correlations (v = -.487, p < .000, male, v = -.509, p < .000, female) within 4 hours after a meal and significant positive correlations (v = .434, p < .000, male, v .440, p < .000, female) afterward. 5. The wall thicknesses of GB were significant positive correlations (t = .310, p < .002, male, t = .116, p < .246, female) within 3 hours after a meal and significant negative correlations (t = -.288, p < .010, male, t = -.126, p < 7.10, female) afterward. 6. The relationship between volume and wall thickness of GB showed significant negative correlation.

  18. Quantitative CT: Associations between Emphysema, Airway Wall Thickness and Body Composition in COPD

    DEFF Research Database (Denmark)

    Rutten, Erica P A; Grydeland, Thomas B; Pillai, Sreekumar G;

    2011-01-01

    The objective of the present study was to determine the association between CT phenotypes-emphysema by low attenuation area and bronchitis by airway wall thickness-and body composition parameters in a large cohort of subjects with and without COPD. In 452 COPD subjects and 459 subjects without COPD...

  19. Measurement of thickness of austenitic overlays on carbon steel walls using a magnetic method

    International Nuclear Information System (INIS)

    Mechanical and magnetic methods are used for measuring the thickness of austenitic overlays on the walls of carbon steel pressure vessels. Specific problems pertaining to the magnetic methods are briefly discussed. A magnetic thickness gage has been developed for overlays using the principle of ferrite effect suppression. Thickness gaging is done by aligning the gage with the layer to be measured on the overlay side. Basic accuracy of the instrument is 7% for overlays containing 2 to 8% ferrite. For the ferrite content 0 to 2% or 8 to 10%, accuracy reduces to roughly 12%. The method is simple, reliable and versatile during the manufacture of a pressure vessel and after it is finished. The economic benefit is considerable because it allows overlaying of a thickness which practically is without reserve; each millimeter of the austenitic layer thickness on the pressure vessel costs more than a million Czechoslovak crowns. (Z.M.). 7 figs., 5 refs

  20. Method for non contacting gauging of the wall thickness of tubes by backscattering of radiation

    International Nuclear Information System (INIS)

    A method is described to make a non contacting rapid and precise estimation of the wall thickness of steel tubes as well as the maximum and the minimum by the aid of backscattering of 137Cs gamma rays. The construction of the measuring head is given. By fitting the measured backscattering values to defined curves a mathematical expression for the influences of the opposite tube wall and the tube diameter was found. By making two measurements on exactly opposed places every pair of values can be assigned unmistakably to the corresponding wall thickness if the diameter is well known. By gauging on four positions each staggered at 90deg C the maximum and minimum can be calculated. The obtainable accuracy is given by an estimation of errors. (Author)

  1. Creep collapse of thick-walled heat transfer tube subjected to external pressure at high temperature

    International Nuclear Information System (INIS)

    A series of creep collapse tests of thick-walled heat transfer tube were examined experimentally and analytically to confirm an analytical method for creep deformation behavior of a heat transfer tube of an intermediate heat exchanger (IHX) at a depressurization accident of secondary cooling system of HTTR (High Temperature Engineering Test Reactor). The tests were carried out using thick-walled heat transfer tubes made of Hastelloy XR at 950degC in helium gas environment. The predictions of creep collapse time obtained by a general purpose FEM-code ABAQUS were in good agreement with the experimental results. A lot of cracks were observed on the outer surface of the test tubes after the creep collapse. However, the cracks did not pass through the tube wall and, therefore, the leak tightness was maintained regardless of a collapse deformation for all tubes tested. (author)

  2. Room temperature synthesis of indium tin oxide nanotubes with high precision wall thickness by electroless deposition

    Directory of Open Access Journals (Sweden)

    Mario Boehme

    2011-02-01

    Full Text Available Conductive nanotubes consisting of indium tin oxide (ITO were fabricated by electroless deposition using ion track etched polycarbonate templates. To produce nanotubes (NTs with thin walls and small surface roughness, the tubes were generated by a multi-step procedure under aqueous conditions. The approach reported below yields open end nanotubes with well defined outer diameter and wall thickness. In the past, zinc oxide films were mostly preferred and were synthesized using electroless deposition based on aqueous solutions. All these methods previously developed, are not adaptable in the case of ITO nanotubes, even with modifications. In the present work, therefore, we investigated the necessary conditions for the growth of ITO-NTs to achieve a wall thickness of around 10 nm. In addition, the effects of pH and reductive concentrations for the formation of ITO-NTs are also discussed.

  3. Real-time dielectric-film thickness measurement system for plasma processing chamber wall monitoring.

    Science.gov (United States)

    Kim, Jin-Yong; Chung, Chin-Wook

    2015-12-01

    An in-situ real-time processing chamber wall monitoring system was developed. In order to measure the thickness of the dielectric film, two frequencies of small sinusoidal voltage (∼1 V) signals were applied to an electrically floated planar type probe, which is positioned at chamber wall surface, and the amplitudes of the currents and the phase differences between the voltage and current were measured. By using an equivalent sheath circuit model including a sheath capacitance, the dielectric thickness can be obtained. Experiments were performed in various plasma condition, and reliable dielectric film thickness was obtained regardless of the plasma properties. In addition, availability in commercial chamber for plasma enhanced chemical vapor deposition was verified. This study is expected to contribute to the control of etching and deposition processes and optimization of periodic maintenance in semiconductor manufacturing process. PMID:26724022

  4. Real-time dielectric-film thickness measurement system for plasma processing chamber wall monitoring

    Science.gov (United States)

    Kim, Jin-Yong; Chung, Chin-Wook

    2015-12-01

    An in-situ real-time processing chamber wall monitoring system was developed. In order to measure the thickness of the dielectric film, two frequencies of small sinusoidal voltage (˜1 V) signals were applied to an electrically floated planar type probe, which is positioned at chamber wall surface, and the amplitudes of the currents and the phase differences between the voltage and current were measured. By using an equivalent sheath circuit model including a sheath capacitance, the dielectric thickness can be obtained. Experiments were performed in various plasma condition, and reliable dielectric film thickness was obtained regardless of the plasma properties. In addition, availability in commercial chamber for plasma enhanced chemical vapor deposition was verified. This study is expected to contribute to the control of etching and deposition processes and optimization of periodic maintenance in semiconductor manufacturing process.

  5. Lipogenesis in arterial wall and vascular smooth muscular cells: regulation and abnormalities in insulin-resistance

    Directory of Open Access Journals (Sweden)

    Feugier Patrick

    2009-12-01

    Full Text Available Abstract Background Vascular smooth muscular cells (VSMC express lipogenic genes. Therefore in situ lipogenesis could provide fatty acids for triglycerides synthesis and cholesterol esterification and contribute to lipid accumulation in arterial wall with aging and during atheroma. Methods We investigated expression of lipogenic genes in human and rat arterial walls, its regulation in cultured VSMC and determined if it is modified during insulin-resistance and diabetes, situations with increased risk for atheroma. Results Zucker obese (ZO and diabetic (ZDF rats accumulated more triglycerides in their aortas than their respective control rats, and this triglycerides content increased with age in ZDF and control rats. However the expression in aortas of lipogenic genes, or of genes involved in fatty acids uptake, was not higher in ZDF and ZO rats and did not increase with age. Expression of lipogenesis-related genes was not increased in human arterial wall (carotid endarterectomy of diabetic compared to non-diabetic patients. In vitro, glucose and adipogenic medium (ADM stimulated moderately the expression and activity of lipogenesis in VSMC from control rats. LXR agonists, but not PXR agonist, stimulated also lipogenesis in VSMC but not in arterial wall in vivo. Lipogenic genes expression was lower in VSMC from ZO rats and not stimulated by glucose or ADM. Conclusion Lipogenic genes are expressed in arterial wall and VSMC; this expression is stimulated (VSMC by glucose, ADM and LXR agonists. During insulin-resistance and diabetes, this expression is not increased and resists to the actions of glucose and ADM. It is unlikely that this metabolic pathway contribute to lipid accumulation of arterial wall during insulin-resistance and diabetes and thus to the increased risk of atheroma observed in these situations.

  6. Distribution of ice thickness and subglacial topography of the "Chinese Wall" around Kunlun Station, East Antarctica

    Science.gov (United States)

    Cui, Xiang-Bin; Sun, Bo; Su, Xiao-Gang; Guo, Jing-Xue

    2016-03-01

    As fundamental parameters of the Antarctic Ice Sheet, ice thickness and subglacial topography are critical factors for studying the basal conditions and mass balance in Antarctica. During CHINARE 24 (the 24th Chinese National Antarctic Research Expedition, 2007/08), the research team used a deep ice-penetrating radar system to measure the ice thickness and subglacial topography of the "Chinese Wall" around Kunlun Station, East Antarctica. Preliminary results show that the ice thickness varies mostly from 1600 m to 2800 m along the "Chinese Wall", with the thickest ice being 3444 m, and the thinnest ice 1255 m. The average bedrock elevation is 1722 m, while the minimum is just 604 m. Compared with the northern side of the ice divide, the ice thickness is a little greater and the subglacial topography lower on the southern side, which is also characterized by four deep valleys. We found no basal freeze-on ice in the Gamburtsev Subglacial Mountains area, subglacial lakes, or water bodies along the "Chinese Wall". Ice thickness and subglacial topography data extracted from the Bedmap 2 database along the "Chinese Wall" are consistent with our results, but their resolution and accuracy are very limited in areas where the bedrock fluctuates intensely. The distribution of ice thickness and subglacial topography detected by ice-penetrating radar clarifies the features of the ice sheet in this "inaccessible" region. These results will help to advance the study of ice sheet dynamics and the determination of future locations of the GSM's geological and deep ice core drilling sites in the Dome A region.

  7. Quantification of cross-sectional artery wall motion with IVUS image registration

    Science.gov (United States)

    Oakeson, Kevin D.; Zhu, Hui; Friedman, Morton H.

    2004-04-01

    Atherosclerotic lesions have been shown to have different mechanical properties than the non-diseased artery. Calculating vessel wall strain from cross-sectional vessel wall motions allows for the measurement of local stiffness. In this paper, a robust method is developed to track cross-sectional displacements of an artery wall using two different intravascular ultrasound (IVUS) images acquired at two different pressure levels respectively. First, the vessel wall region in one image is segmented semi-automatically by refining two spline-based contours to the locations of inner and outer vessel wall borders. Then the ringlike wall region in one image is registered to its counterpart in the other image in polar coordinates. The registration is performed by minimizing an energy function of the 2D motion field based on a spline-deformable-model. Both intensity and gradient information of the images are used to construct the energy function so that an accurate registration can be achieved. Registration accuracy was tested on simulated motions using IVUS images of a human coronary artery and a porcine carotid. The wall displacement fields calculated from real motion images are also demonstrated.

  8. A portable gamma backscatter gauge for measurement of wall thickness of pipes and boilers

    International Nuclear Information System (INIS)

    A portable instrument for 'in situ' measurement of wall thickness of boilers and tubes, working on the principle of gamma back-scattering, and using a low activity gamma source (30 micro-curies Co60) and a scintillation detector is described. The probe consists of a gamma source and an NaI(tl) scintillation detector coupled to a multiplier phototube. The EHT circuit for the PM tube and the preamplifier are also incorporated inside the probe. The probe is coupled to a measuring part consisting of an amplifier for amplifying the pulses from the probe, a single channel analyser which is set to select pulses corresponding to energy of backscattered gammas and a count-rate meter to count the number of pulses. With prior calibration, count-rate can be correlated to the thickness of the backscatter eg. boiler wall or tube wall. The instrument can measure wall thicknesses upto 2 cm of steel with an accuracy of +- 10%. The unit can also be used for detection of erosion and blocking in pipes carrying process materials. The electronic circuitry is fully transistorised and works on readily available flashlight cells. The complete system is portable and well suited for field use. (author)

  9. The effect of fig wall thickness in Ficus erecta var. beecheyana on parasitism

    Science.gov (United States)

    Tzeng, Hsy-Yu; Ou, Chern-Hsiung; Lu, Fu-Yuan; Bain, Anthony; Chou, Lien-Siang; Kjellberg, Finn

    2014-05-01

    Fig wasp communities constitute a model system to analyse determinants of community complexity and to investigate how biological interaction networks are maintained. It has been suggested for monoecious figs, that fig pollinating wasps avoid ovipositing in flowers located close to the fig wall because of strong parasitic pressure by wasps ovipositing through the fig wall. This behaviour could help explain why mainly seeds are produced in flowers located close to the fig wall, thus stabilizing the fig-pollinating wasp mutualism. In this contribution we explore, for dioecious figs, whether ovipositor length of parasitic species may really be limiting. In dioecious figs, functionally male figs produce pollinating wasps and pollen while female figs produce only seeds, facilitating selection of traits favouring pollinator reproduction in male figs. We show in Ficus erecta that fig walls are thicker in male figs than in female figs. Male figs presenting thick walls, thicker than the length of the parasites' ovipositors, went unparasitized while male figs presenting thinner walls were systematically parasitized. Hence, in F. erecta, ovipositor length of the parasites is limiting access to some figs. However, we also show that in another dioecious species, Ficus formosana, presenting thin walled male figs, no fig is protected against oviposition by its two parasites. Hence in dioecious as well as in monoecious figs, in some Ficus species, ovipositors of the parasites are limiting access to ovules, while in other Ficus species all ovules are exposed to parasitism.

  10. Ultrasonic tests for quantitative defect sizing using SAFT in thick-walled and thin-walled plant components

    International Nuclear Information System (INIS)

    SAFT is an efficient ultrasonic defect sizing method. It is a signal processing and evaluation method which uses the travel time of ultrasonic waves emitted and received by transceivers with divergent sound waves. In the investigations, conventional transceivers were replaced by transducer arrays whose incidence angles were varied during the measurements. Artificially applied cracks in the 6 mm plating of a test piece with a wall thickness of 179 mm, which models part of the reactor pressure vessel, were identified and analyzed. Further, transducer array measurements were made on a thin-walled test element which is a 1:1 model of a connecting piece in order to analyze artificially applied defects in the weld with which a heat protection tube was fastened inside the connecting piece. Accompanying model calculations using a SAFT algorithm prove the correctness of the measured results. (orig.)

  11. Segmentation of the Common Carotid Artery Walls Based on a Frequency Implementation of Active Contours: Segmentation of the Common Carotid Artery Walls

    OpenAIRE

    Bastida-Jumilla, M Consuelo; Menchón-Lara, Rosa M; Morales-Sánchez, Juan; Verdú-Monedero, Rafael; Larrey-Ruiz, Jorge; Sancho-Gómez, José Luis

    2012-01-01

    Atherosclerosis is one of the most extended cardiovascular diseases nowadays. Although it may be unnoticed during years, it also may suddenly trigger severe illnesses such as stroke, embolisms or ischemia. Therefore, an early detection of atherosclerosis can prevent adult population from suffering more serious pathologies. The intima–media thickness (IMT) of the common carotid artery (CCA) has been used as an early and reliable indicator of atherosclerosis for years. The IMT is manually compu...

  12. CORRELATIONS OF DIFFERENT STRUCTURAL AND FUNCTIONAL CHARACTERISTICS OF ARTERIAL WALL WITH TRADITIONAL CARDIOVASCULAR RISK FACTORS IN HEALTHY PEOPLE OF DIFFERENT AGE. PART 1

    Directory of Open Access Journals (Sweden)

    I. D. Strazhesko

    2016-05-01

    Full Text Available Arterial wall status is determined by several characteristics, the main of them are as follows: pulse wave velocity (PWV, carotid arteries intima-media thickness (IMT, the presence of atherosclerotic plaques, endothelium-dependent vasodilation (EDVD. When these parameters change, the risk for cardiovascular disease (CVD grows. The nature of relationship between these indices in people without CVD clinical signs is understudied, especially in those of older age.Aim. To estimate correlations between different parameters of arterial wall in patients of different age without CVD.Material and methods. A total of 303 people aged 25-91 years without any manifestations of CVD or other chronic diseases and without regular medical treatment were examined. PWV estimation, carotid ultrasound with IMT measurement and atherosclerotic plaques amount calculation and EDVD estimation using reactive hyperemia test were performed. Results. Patients without CVD clinical signs rather often reveal arterial wall lesions already in the younger age group (mean age 40.9±8.7: reduced EDVD – in 26% of the cases, the presence of atherosclerotic plaques – in 22%, increased PWV – in 15%, increased IMT – in 8%. The prevalence of arterial wall alterations in the older age group (mean age 61.19±8.5 increase many-fold. All arterial wall parameters correlate with age. The stronger correlation was revealed between IMT and the amount of atherosclerotic plaques: r=0.46 (р<0.001 in the younger group and r=0.47 (р<0.001 in the older one. We didn’t find any relationship between PWV and EDVD in the younger group and between PWV and the amount of atherosclerotic plaques in the older one. Thickened carotid intima-media increases the risk of arterial stiffness by 2.3 times.Conclusion. Estimation of the state of arterial wall in people of young age without CVD allows detecting individuals who require active CVD prevention. Increased stiffness of arterial wall and the development

  13. All- Ceramic Crown Preparation and the Remained wall Thickness of the Pulp Chamber

    Directory of Open Access Journals (Sweden)

    Mohammadzadeh Akhlaghi N.

    2012-12-01

    Full Text Available tatement of Problem: A minimally invasive method of preparation is essential to prevent tooth structure weakening and pulp irritation; especially for mandibular anterior single-tooth all-ceramic crowns. According to many investigations, one of the most important reasons of pulp injury caused by tooth preparation for different restorative procedures is reduced “remained wall thickness” (RWT. In order to protect the pulp from irritation, it is necessary to maintain a 0.5 mm of RWT.Purpose: The purpose of the present study was to evaluate the effect of all-ceramic crown preparation on pulp chamber RWT of mandibular incisors.Materials and Method: Mesiodistal and buccolingual initial images of 24 ex-tracted mandibular incisors were provided. The pulp chamber initial wall thick-nesses of buccal, lingual and proximal surfaces of cervical, 1and 2 mm above the cervical areas and also the incisal surfaces of incisal sections were measured using digital radiography and Photoshop software. After all-ceramic crown preparation, images were provided at the same initial positions. The initial and remained pulp chamber wall thicknesses were statistically evaluated and analyzed by ANOVA, paired t-test and a post hoc Tukey test.Results: Repeated measures ANOVA showed that the mean of pre- or post-preparation wall thicknesses were not significantly different for each surface at the three horizontal levels (p> 0.05. However, there were significant differences between the surfaces for each section. Comparison of pre- and post-preparation wall thicknesses revealed significant differences (p< 0.05. Proximal surfaces of cervical sections had the least RWT (0.42±0.12.Conclusion: According to the results of the present study, the least amount of initial and remained wall thicknesses of pulp chamber were related to the proximal surfaces, particularly in cervical areas. Therefore a reduction of preparation to 0.7 mm is suggested to prevent future pulp injury for

  14. Chest wall thickness measurements and the dosimetric implications for male workers in the uranium industry

    International Nuclear Information System (INIS)

    The Human Monitoring Laboratory has measured the chest wall thickness and adipose mass fraction of a group of workers at three Canadian uranium refinery, conversion plant, and fuel fabrication sites using ultrasound. A site specific biometric equation has been developed for these workers, who seem to be somewhat larger than other workers reported in the literature. The average chest wall thickness of the seated persons measured at the uranium conversion plant and refinery was about 3.8 cm, and at the fuel fabrication facility was 3.4 cm. These values are not statistically different. Persons measured in a seated geometry had a thinner chest wall thickness than persons measured in a supine geometry - the decrease was in the range of 0.3 cm to 0.5 cm. It follows that a seated geometry will give a lower MDA (or decision level) than a supine geometry. Chest wall thickness is a very important modifier for lung counting efficiency and this data has been put into the perspective of the impending Canadian dose limits that will reduce the limit of occupationally exposed workers to essentially 20 mSv per year. Natural uranium must be measured based on the 235U emissions at these type of facilities. The refining and conversion process removes 234Th and the equilibrium is disturbed. This is unfortunate as the MDA values for this nuclide are approximately a factor of three lower than the values quoted below. The sensitivity of the germanium and phoswich based lung counting system has been compared. Achievable MDA's (30 minute counting time) with a four-phoswich-detector array lie in the range of 4.7 mg to 13.5 mg of natural uranium based on the 235U emissions over a range of chest wall thicknesses of 1.6 cm to 6.0 cm. The average achievable MDA is about 8.5 mg which can be reduced to about 6.2 mg by doubling the counting time. Similarly, MDA's (30 minute counting time) obtainable with a germanium lung counting system will lie in the range of 3 mg to 28 mg of natural uranium

  15. Free Tensor Fascia Lata Flap and Synthetic Mesh Reconstruction for Full-Thickness Chest Wall Defect

    OpenAIRE

    Jumpei Ono; Akira Takeda; Minekatsu Akimoto; Akira Iyoda; Yoshio Matsui; Yukitoshi Satoh; Eiju Uchinuma

    2013-01-01

    A large full-thickness chest wall defect over 10 cm in diameter requires skeletal reconstruction and soft tissue coverage. Use of various flaps for soft tissue coverage was previously reported, but en bloc resection in each case affects these flap pedicles and sizes. We present a case of a 74-year-old man with a soft tissue tumor involving the left lateral chest wall. We performed an en block resection and skeletal reconstruction using a mesh, free tensor fascia lata (TFL) flap for soft tissu...

  16. Wall thickness measurements of tubes by Internal Rotary Inspection System (IRIS)- a comparative study with metallography

    International Nuclear Information System (INIS)

    Internal Rotary Inspection System (IRIS) is a relatively new ultrasonic system of heat exchanger/ steam condenser tubes and pipelines for measurement of wall thinning and pitting due to corrosion. The wall thickness measurements made during a scan around the circumference of the tube are displayed as a stationary rectilinear display of circumferential cross section (Bscan) of the tube. The paper describes the results obtained on tubes of various materials used in process industries having corrosion on inner and outer surfaces of the tube. (author)

  17. Ultrasound Estimated Bladder Weight and Measurement of Bladder Wall Thickness-Useful Noninvasive Methods for Assessing the Lower Urinary Tract?

    NARCIS (Netherlands)

    E. Bright; M. Oelke; A. Tubaro; P. Abrams

    2010-01-01

    Purpose: In the last decade interest has arisen in the use of ultrasound derived measurements of bladder wall thickness, detrusor wall thickness and ultrasound estimated bladder weight as potential diagnostic tools for conditions known to induce detrusor hypertrophy. However, to date such measuremen

  18. Elastic analysis of heterogeneous thick-walled spherical pressure vessels with parabolic varying properties

    Science.gov (United States)

    Karami, Keyhan; Abedi, Majid; Zamani Nejad, Mohammad; Lotfian, Mohammad Hassan

    2012-12-01

    On the basis of plane elasticity theory (PET), the displacement and stress components in a thick-walled spherical pressure vessels made of heterogeneous materials subjected to internal and external pressure is developed. The mechanical properties except the Poisson's ratio are assumed to obey the parabolic variations throughout the thickness. Effect of material inhomogeneity on the elastic deformations and stresses is investigated. The analytical solutions and the solutions carried out through the FEM have a good agreement. The values used in this study are arbitrary chosen to demonstrate the effect of inhomogeneity on displacements, and stresses distributions.

  19. An experimental study on the effect of fluorouracil of two preparations on target arterial wall

    International Nuclear Information System (INIS)

    Objective: To probe into the influence of 5-Fu polyphase liposome and 5-Fu solution injection on a target artery. Methods: Fourteen rabbits were divided into the group A of 5-Fu polyphase liposome and group B of 5-Fu injection. Of 7 cases per group, 5 cases had a femoral artery approach and 2 cases via an ear artery. Angiography and pathological examinations under light microscope of the femoral artery were made 7 days after administration via femoral artery and pathological examination under electron microscope of the ear artery 24 hours after administration via ear artery. Results: In group B, the local narrowing was clearly shown in 4 of 5 cases of femoral arteriography. Denudation and fragmentation of hyperplastic endothelial cells, rupture and discontinuity of internal elastic membrane were seen under light microscope in the stenotic vessels. Fragmentation of endothelial cell membrane, vacuolization of cytoplasm and hazy mitochondrial structures were seen under electron microscope. In group A, femoral arteriography was normal, and only mild degree of exfoliation and hyperplasia of endothelium were seen under light microscope. Integrity of endothelial cell membrane, vacuoles in cytoplasm, swollen mitochondria with visible ridge and irregular nucleus were seen under electron microscope. Conclusions: The stimulation and injury to target arterial wall by 5-Fu polyphase liposome was obviously milder than that of 5-Fu solution injection

  20. Measurements of the human anterior chest wall by ultrasound and estimates of chest wall thickness for use in determination of transuranic nuclides in the lung

    International Nuclear Information System (INIS)

    The low energy photons on which the in vivo detection of plutonium isotopes and americium 241 is based are severely attenuated in body tissues. To assess the activity of these radionuclides in the lungs by external measurement it is necessary to estimate or measure the thickness of tissues overlying the lungs. It is also desirable to distinguish between muscle and adipose tissues in the chest wall because of the difference in their attenuation properties. Diagnostic ultrasound machines developed for medical use are suitable for this purpose. Experience gained since 1978 in ultrasonic measurements of chest wall thickness and the current measurement procedure are described. The concept of ''equivalent muscle chest wall thickness'' is introduced and a method for calculating the parameter is given. Both chest wall thickness and equivalent muscle chest wall thickness have been found to correlate well with Quetelets Index (weight divided by height squared). Residual correlations with other parameters have been examined. Empirical formulae are given that can be used to predict the chest wall thickness and equivalent muscle chest wall thickness of a subject of given weight, height and age. (author)

  1. A NEW UNSTEADY THREE DIMENSIONAL MODEL FOR MACROMOLECULAR TRANSPORT AND WATER FILTRATION ACROSS THE ARTERIAL WALL

    Institute of Scientific and Technical Information of China (English)

    黄浩; 温功碧

    2001-01-01

    A new unsteady three-dimensional convective-diffusive mathematical model for the transportation of macromolecules and water across the arterial wall was proposed . After the formation of leaky junctions due to the mitosis of endothelial cell of the arterial wall, the macromolecular transport happens surrounding the leaky cells. The arterial wall was divided into four layers: the endothelial layer, the subendothelial intima, the internal elastic lamina and the media for the convenience of research. The time-dependent concentration growth,the effect of the shape of endothelial cell and the effect of physiological parameters were analyzed. The analytical solution of velocity field and pressure field of water flow across the arterial wall were obtained; and concentration distribution of three macromolecules ; LDL,HRP and Albumin, were calculated with numerical simulation method. The new theory predicts, the maximum and distribution areas of time dependent concentration with round shape endothelial cell are both larger than that with ellipse-shape endothelial cell. The model also predicts the concentration growth is much alike that of a two-dimensional model and it shows that the concentration reaches its peak at the leaky junction where atherosclerotic formation frequently occurs and falls down rapidly in a limited area beginning from its earlier time growth to the state when macromolecular transfer approaches steadily. These predictions of the new model are in agreement with the experimental observation for the growth and concentration distribution of LDL and Albumin.

  2. Standard guide for mutual inductance bridge applications for wall thickness determinations in boiler tubing

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This guide describes a procedure for obtaining relative wall thickness indications in ferromagnetic and non-ferromagnetic steels using the mutual inductance bridge method. The procedure is intended for use with instruments capable of inducing two substantially identical magnetic fields and noting the change in inductance resulting from differing amounts of steel. It is used to distinguish acceptable wall thickness conditions from those which could place tubular vessels or piping at risk of bursting under high temperature and pressure conditions. 1.2 This guide is intended to satisfy two general needs for users of industrial Mutual Inductance Bridge (MIB) equipment: (1) the need for a tutorial guide addressing the general principles of Mutual Inductance Bridges as they apply to industrial piping; and (2) the need for a consistent set of MIB performance parameter definitions, including how these performance parameters relate to MIB system specifications. Potential users and buyers, as well as experienced M...

  3. Simulation on the Effect of Bottle Wall Thickness Distribution using Blow Moulding Technique

    Science.gov (United States)

    Suraya, S.; Azman, M. D.; Fatchurrohman, N.; Jaafar, A. A.; Yusoff, A. R.

    2016-02-01

    The aims of this study are to assess the deformation behavior of a polymeric material during a blow moulding process. Transient computations of two dimensional model of a PP bottle were performed using ANSYS Polyflow computer code to predict the wall thickness distribution at four different parison's diameter; 8mm, 10mm, 18mm, and 20mm. Effects on the final wall thickness diameter and time step are studied. The simulated data shows that the inflation performance degrades with increasing parison diameter. It is concluded that the blow moulding process using 10mm parison successfully meet the product processing requirements. Factors that contribute to the variation in deformation behaviour of the plastic during the manufacturing process are discussed.

  4. Breast arterial calcification and risk of carotid atherosclerosis: Focusing on the preferentially affected layer of the vessel wall

    Energy Technology Data Exchange (ETDEWEB)

    Sedighi, Nahid, E-mail: nsedighi@sina.tums.ac.ir [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of); Radmard, Amir Reza, E-mail: radmard@ams.ac.ir [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of); Radmehr, Ali, E-mail: radmehr@sina.tums.ac.ir [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of); Hashemi, Pari, E-mail: phtums@yahoo.com [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of); Hajizadeh, Abdolmahmoud, E-mail: mroomezi@yahoo.com [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of); Taheri, Amir Pejman Hashemi, E-mail: hashemip@sina.tums.ac.ir [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of)

    2011-08-15

    Objective: To assess the relationship between breast arterial calcification (BAC) detected on screening mammography and atherosclerosis of carotid arteries considering the most likely involved layer of the arterial wall. Materials and methods: A total of 537 consecutive women who underwent screening mammography were enrolled in this study. Seventy-nine subjects having BAC, aged 46-75 years, and 125 age-matched controls from those without BAC were selected for ultrasound examination of carotid arteries assessing intima-media thickness (IMT) and plaque presence. Participants were divided into three groups of risk including, low-risk: IMT < 0.6 mm without plaque, medium-risk: 0.6 mm {<=} IMT {<=} 0.8 mm without plaque and high-risk: IMT > 0.8 mm and/or plaque. Risk factors for atherosclerosis were obtained from medical records for independent effects. Results: BAC was present in 14.7% of mammograms. According to multivariable logistic regression analyses, significant association was identified between the carotid atherosclerosis risk and presence of BAC. Compared to women with IMT < 0.6 mm, those with 0.6 mm {<=} IMT{<=} 0.8 mm and IMT > 0.8 mm had OR (95% CI) of 4.88 (1.47-16.16) and 23.36 (4.54-120.14), respectively. The OR (95% CI) for carotid plaque was 3.13 (1.3-7.57). There was no interaction between IMT category and plaque. Significant associations were also detected with postmenopausal duration (P = 0.02) and hypertension (P = 0.004). Conclusion: The risk of carotid atherosclerosis increases with the presence of BAC. Women with BAC are more likely to have thicker IMT than plaque, which could be attributed to the preferentially similar affected layer of media causing thick IMT rather than plaque.

  5. Breast arterial calcification and risk of carotid atherosclerosis: Focusing on the preferentially affected layer of the vessel wall

    International Nuclear Information System (INIS)

    Objective: To assess the relationship between breast arterial calcification (BAC) detected on screening mammography and atherosclerosis of carotid arteries considering the most likely involved layer of the arterial wall. Materials and methods: A total of 537 consecutive women who underwent screening mammography were enrolled in this study. Seventy-nine subjects having BAC, aged 46-75 years, and 125 age-matched controls from those without BAC were selected for ultrasound examination of carotid arteries assessing intima-media thickness (IMT) and plaque presence. Participants were divided into three groups of risk including, low-risk: IMT 0.8 mm and/or plaque. Risk factors for atherosclerosis were obtained from medical records for independent effects. Results: BAC was present in 14.7% of mammograms. According to multivariable logistic regression analyses, significant association was identified between the carotid atherosclerosis risk and presence of BAC. Compared to women with IMT 0.8 mm had OR (95% CI) of 4.88 (1.47-16.16) and 23.36 (4.54-120.14), respectively. The OR (95% CI) for carotid plaque was 3.13 (1.3-7.57). There was no interaction between IMT category and plaque. Significant associations were also detected with postmenopausal duration (P = 0.02) and hypertension (P = 0.004). Conclusion: The risk of carotid atherosclerosis increases with the presence of BAC. Women with BAC are more likely to have thicker IMT than plaque, which could be attributed to the preferentially similar affected layer of media causing thick IMT rather than plaque.

  6. Regional calcium distribution and ultrasound images of the vessel wall in human carotid arteries

    Science.gov (United States)

    Szikszai, Z.; Kertész, Zs.; Uzonyi, I.; Szíki, G. Á.; Magyar, M. T.; Molnár, S.; Ida, Y.; Csiba, L.

    2005-04-01

    Arterial calcification can take place at two sites in the vessel wall: the intima and the media. Intimal calcification occurs exclusively within atherosclerotic plaques, while medial calcification may develop independently. Extensive calcified plaques in the carotid arteries can be easily detected by B-mode ultrasonic imaging. The calcium content might correlate with the ultrasound reflectance of the vessel wall, and could be a surrogate marker for arteriosclerosis. In this study, segments of human carotid arteries collected at autopsy were examined by ultrasonography in vitro and calcium distributional maps of sections from the same segments were determined by particle induced X-ray emission. Our aim was to make a first step towards investigating the relationship between the calcium distributional maps and the respective ultrasound images.

  7. Accurate evaluation of viscoelasticity of radial artery wall during flow-mediated dilation in ultrasound measurement

    Science.gov (United States)

    Sakai, Yasumasa; Taki, Hirofumi; Kanai, Hiroshi

    2016-07-01

    In our previous study, the viscoelasticity of the radial artery wall was estimated to diagnose endothelial dysfunction using a high-frequency (22 MHz) ultrasound device. In the present study, we employed a commercial ultrasound device (7.5 MHz) and estimated the viscoelasticity using arterial pressure and diameter, both of which were measured at the same position. In a phantom experiment, the proposed method successfully estimated the elasticity and viscosity of the phantom with errors of 1.8 and 30.3%, respectively. In an in vivo measurement, the transient change in the viscoelasticity was measured for three healthy subjects during flow-mediated dilation (FMD). The proposed method revealed the softening of the arterial wall originating from the FMD reaction within 100 s after avascularization. These results indicate the high performance of the proposed method in evaluating vascular endothelial function just after avascularization, where the function is difficult to be estimated by a conventional FMD measurement.

  8. Influence of the myocardial bridging phenomenon on the myocardial structure and the coronary arteries wall structure changes

    OpenAIRE

    Tomanović-Koković Jelena; Teofilovski-Parapid Gordana; Oklobdžija Mirjana; Kanjuh Vladimir; Kovačević Slobodan; Parapid Biljana; Koković Vladimir

    2006-01-01

    Background/Aim. Our research was performed to evaluate the influences of the myocardial bridging of coronary arteries on the myocardial and coronary arteries wall structure changes, that could be a reason for multiple heart malfunctions. Methods. We analyzed the autopsy material, collected during a five-years period, and especially the group of 575 cases with the major aim to diagnose mors naturalis. In all cases with the presence of myocardial bridge over the arterial coronary wall revealed ...

  9. Using The Descending Aortic Wall Thickness Measured In Transesophageal Echocardiography As A Risk Marker For Aortic Dissection

    OpenAIRE

    Zaher Fanari; Sumaya Hammami; Muhammad Baraa Hammami; Safa Hammami; Chete Eze-Nliam; Weintraub, William S.

    2015-01-01

    Objective: The aim of this study is to estimate whether aortic wall thickness is increased in patients with Aortic dissection (AD) compared to low risk control group and can be used in addition to aortic diameter as a risk marker of AD. Background: AD occurs due to pathologies that may increase thickness of the aortic wall. Transesophageal echocardiography (TEE) has the ability to visualise both the thoracic aortic wall and lumen. Aortic diameter has been used to predict aortic dissection...

  10. Wall thickness measurements of pipes in heat exchangers using ultrasonic waves

    International Nuclear Information System (INIS)

    Heat exchangers and reactors used in the chemical industry for heat exchange and conversion are exposed to the influence of corrosion and wear. These defect parts must be identified during operation in order to prevent damage occurring to the plant and to restrict break-down times. By means of manual ultrasonic wall thickness measurement worn parts in piping both on the inner and outer sides can be reliably detected in the assembled state. (orig.)

  11. Inspection of seamless thick-walled steel tubes of 1 Cr 13 with ultrasonic spread

    International Nuclear Information System (INIS)

    A technique of nondestructive inspection with ultrasound spread, which is a new nonconventional way of ultrasonic inspection, used the method of water-immersed single probe transverse wave sound spread to detect the flaws of the outer and inner surface of 1 Cr 13 seamless steel tubes. The thickness of the wall is 16 mm, the outside diameter 58 mm, and the inside diameter is 26 mm. The micrographic examination of the products proves that this technique is practicable. (orig.)

  12. Ultrasound Thickness of Bladder Wall in Continent and Incontinent Women and Its Correlation with Cystometry

    OpenAIRE

    Edney Norio Otsuki; Edward Araujo Júnior; Emerson Oliveira; Marair Gracio Ferreira Sartori; Manoel João Batista Castelo Girão; Zsuzsanna Ilona Katalin Jármy-Di Bella

    2014-01-01

    Objective. To compare bladder wall thickness in two kinds of urinary incontinent women—stress urinary incontinence (SUI) and overactive bladder (OAB) with urodynamic detrusor overactivity (DO), and to compare them with continent patients by ultrasound, also, correlate with cystometric results in incontinent women. Methods. 91 women were divided into the following groups: continent (n = 31), SUI (n = 30), and DO (n = 30) groups after clinical evaluation and urodynamic test (only in incontinent...

  13. Bladder wall thickness and ultrasound estimated bladder weight in healthy adults with portative ultrasound device

    OpenAIRE

    Selcen Kanyilmaz; Funda Atamaz Calis; Yasemin Cinar; Yesim Akkoc

    2013-01-01

    Background: The aim of this study was to investigate bladder wall thickness (BWT) and ultrasound estimated bladder weight (UEBW) values in healthy population with a portative ultrasound device and their relationship with demographic parameters. Materials and Methods: The study was carried out in Neurorehabilitation Clinic of Ege University Hospital. Ninety-five subjects (48 women and 47 men) aged between 18 and 56 were included in the study. BWT and UEBW were determined non-invasively with a ...

  14. Manual versus automatic bladder wall thickness measurements: a method comparison study

    OpenAIRE

    Oelke, M.; Mamoulakis, C; Ubbink, D T; Rosette, de la, J.J.M.C.H.; Wijkstra, H.

    2009-01-01

    Purpose To compare repeatability and agreement of conventional ultrasound bladder wall thickness (BWT) measurements with automatically obtained BWT measurements by the BVM 6500 device. Methods Adult patients with lower urinary tract symptoms, urinary incontinence, or postvoid residual urine were urodynamically assessed. During two subsequent cystometry sessions the infusion pump was temporarily stopped at 150 and 250 ml bladder filling to measure BWT with conventional ultrasound and the BVM 6...

  15. Surgical resection of cerebellar hemangioblastoma with enhanced wall thickness: A report of two cases

    OpenAIRE

    Sun, Zhenxing; Yuan, Dan; SUN, YAXING; YAN, PENGXIANG; Zuo, Huancong

    2015-01-01

    Hemangioblastomas are tumors of the central nervous system, and the cerebellum is the most common site of occurrence. Cerebellar hemangioblastoma with enhanced wall thickness is rare and often misdiagnosed preoperatively. At present, no unified radiological classification system based on magnetic resonance imaging (MRI) findings exists for cerebellar hemangioblastoma, and this tumor type can be solid or cystic mass, according to the MRI findings. The most common presentation of cerebellar hem...

  16. Intima-Media Thickness Does Not Differ between Two Common Carotid Artery Segments in Children

    OpenAIRE

    Heidi Weberruß; Raphael Pirzer; Robert Dalla Pozza; Heinrich Netz; Renate Oberhoffer

    2016-01-01

    Carotid intima-media thickness (cIMT) is a surrogate marker of early atherosclerotic changes in children. cIMT-studies are hard to compare, due to variations in ultrasound protocols, especially regarding the common carotid artery (CCA) segment measured in relation to the bulb. This study's purpose was therefore to compare two distinct CCA segments in children, to see if cIMT values differ substantially according to the site of measurement. cIMT was assessed after power calculation in 30 child...

  17. Design and analysis of Stress on Thick Walled Cylinder with and with out Holes

    Directory of Open Access Journals (Sweden)

    G.Raju

    2015-01-01

    Full Text Available The conventional elastic analysis of thick walled cylinders to final radial & hoop stresses is applicable for the internal pressures up to yield strength of material. The stress is directly proportional to strain up to yield point Beyond elastic point, particularly in thick walled cylinders. The operating pressures are reduced or the material properties are strengthened. There is no such existing theory for the stress distributions around radial holes under impact of varying internal pressure. Present work puts thrust on this area and relation between pressure and stress distribution is plotted graphically based on observations. Here focus is on pure mechanical analysis & hence thermal, effects are not considered. The thick walled cylinders with a radial cross-hole ANSYS Macro program employed to evaluate the fatigue life of vessel. Stresses that remain in material even after removing applied loads are known as residual stresses. These stresses occur only when material begins to yield plastically. Residual stresses can be present in any mechanical structure because of many causes. Residual stresses may be due to the technological process used to make the component. Manufacturing processes lead to plastic deformation. Elasto plastic analysis with bilinear kinematic hardening material is performed to know the effect of hole sizes. It is observed that there are several factors which influence stress intensity factors. The Finite element analysis is conducted using commercial solvers ANSYS & CATIA. Theoretical formulae based results are obtained from MATLAB programs. The results are presented in form of graphs and tables.

  18. Continuous monitoring of the wall thickness of pipelines with ultrasonic waves

    International Nuclear Information System (INIS)

    Pipelines in industrial plants must be constantly monitored due to occurring erosion and corrosion. The determination of the residual wall thickness is generally carried out with ultrasound. Often, the critical points are difficult to access and the pipes insulated. The preparation and evaluation of a measurement is therefore very costly. The measuring system SONOWALL S ultrasonic probes are firmly attached to the pipeline and installed into isolation. The number and position of the probes can be freely selected. Often, the load is not known exactly why the monitoring of the pipe wall thickness over the entire circumference is necessary. The acoustic coupling to the pipe is done with proven adhesives that do not lose their adhesive strength even under changing ambient temperatures. The connecting cables are housed away up to 20 m in an easily accessible place in a terminal box. There can be done a wall thickness measurement with conventional ultrasonic testing devices. By using standardized components, the measuring system meets the requirements of DIN EN 12668 and DIN EN 14127.

  19. Influence of surrounding wall thickness on the fatigue resistance of molars restored with ceramic inlay

    Directory of Open Access Journals (Sweden)

    Shizuma Shibata

    2014-06-01

    Full Text Available The purpose of this study was to evaluate the influence of buccal and lingual wall thickness on the fatigue resistance of molars restored with CAD/CAM ceramic inlays. Forty human third molars were selected and divided into 4 groups, according to the remaining surrounding wall thickness chosen for inlay preparation (n = 10: G1, 2.0 mm; G2, 1.5 mm; G3, 1.0 mm; G4, 0.5 mm. All inlays were made from feldspathic ceramic blocks by a CAD/CAM system, and cemented adhesively. After 1 week stored in distilled water at 37 °C, the specimens were subjected to fatigue testing under the following protocol: 5Hz; pre-load of 200 N for 5,000 cycles, followed by increasing loads of 400, 600, 800, 1000, 1200 and 1400 N for 30,000 cycles each. The specimens were cycled until failure or completion of 185,000 cycles. The survival rate of the groups was compared using the Kaplan-Meier survival curves (p > 0.05. All specimens withstood the fatigue protocol (185,000 cycles, representing a 100% survival rate. The Kaplan-Meier survival curves showed no difference between groups. It can be concluded that the remaining tooth wall thickness did not influence the fatigue resistance of molars restored with CAD/CAM ceramic inlays.

  20. A Reinforcement Plate for Partially Thinned Pressure Vessel Designed to Measure the Thickness of Vessel Wall Applying Ultrasonic Technique

    International Nuclear Information System (INIS)

    It is very hard to preserve the wall thickness of the vessel because of the erosion or corrosion as time goes by. Therefore, the wall thicknesses of heaters in power plants are periodically measured using ultrasonic test. If the integrity of the wall thickness is estimated not to secure, the reinforcement plate is welled on the thinned area of the vessel. The overlay weld of the reinforcement plate on the thinned vessel is normally the fillet welding. As shown by the references, the reinforcement plate with adequate thickness does its role very well before the vessel wall is perforated due to thinning. However, the integrity of shell cannot insure because the weldment is directly applied by the shell side pressure to after the vessel wall is perforated. Therefore, it is needed to measure the thickness of thinned area under the reinforcement plate continuously for preserving integrity and planning the fabrication of replacement vessel. It is impossible to apply the ultrasonic thickness measurement technique after the reinforcement plate is welded on the shell. In this paper new reinforcement plate, which makes it possible to measure the wall thickness under the reinforcement plate applying the ultrasonic technique, is introduced. A method to evaluate the structural integrity of a fillet weldment for the reinforcement plate welded on a pressure vessel is introduced in this paper. Moreover, new reinforcement plate, which makes it possible to measure the wall thickness of pressure vessels under the reinforcement plate applying the ultrasonic technique, is introduced

  1. Local Quantification of Wall Thickness and Intraluminal Thrombus Offer Insight into the Mechanical Properties of the Aneurysmal Aorta.

    Science.gov (United States)

    Martufi, Giampaolo; Satriano, Alessandro; Moore, Randy D; Vorp, David A; Di Martino, Elena S

    2015-08-01

    Wall stress is a powerful tool to assist clinical decisions in rupture risk assessment of abdominal aortic aneurysms. Key modeling assumptions that influence wall stress magnitude and distribution are the inclusion or exclusion of the intraluminal thrombus in the model and the assumption of a uniform wall thickness. We employed a combined numerical-experimental approach to test the hypothesis that abdominal aortic aneurysm (AAA) wall tissues with different thickness as well as wall tissues covered by different thrombus thickness, exhibit differences in the mechanical behavior. Ultimate tissue strength was measured from in vitro tensile testing of AAA specimens and material properties of the wall were estimated by fitting the results of the tensile tests to a histo-mechanical constitutive model. Results showed a decrease in tissue strength and collagen stiffness with increasing wall thickness, supporting the hypothesis of wall thickening being mediated by accumulation of non load-bearing components. Additionally, an increase in thrombus deposition resulted in a reduction of elastin content, collagen stiffness and tissue strength. Local wall thickness and thrombus coverage may be used as surrogate measures of local mechanical properties of the tissue, and therefore, are possible candidates to improve the specificity of AAA wall stress and rupture risk evaluations. PMID:25631202

  2. Smooth Muscle Specific Overexpression of p22phox Potentiates Carotid Artery Wall Thickening in Response to Injury

    Directory of Open Access Journals (Sweden)

    Michael R. Manogue

    2015-01-01

    Full Text Available We hypothesized that transgenic mice overexpressing the p22phox subunit of the NADPH oxidase selectively in smooth muscle (Tgp22smc would exhibit an exacerbated response to transluminal carotid injury compared to wild-type mice. To examine the role of reactive oxygen species (ROS as a mediator of vascular injury, the injury response was quantified by measuring wall thickness (WT and cross-sectional wall area (CSWA of the injured and noninjured arteries in both Tgp22smc and wild-type animals at days 3, 7, and 14 after injury. Akt, p38 MAPK, and Src activation were evaluated at the same time points using Western blotting. WT and CSWA following injury were significantly greater in Tgp22smc mice at both 7 and 14 days after injury while noninjured contralateral carotids were similar between groups. Apocynin treatment attenuated the injury response in both groups and rendered the response similar between Tgp22smc mice and wild-type mice. Following injury, carotid arteries from Tgp22smc mice demonstrated elevated activation of Akt at day 3, while p38 MAPK and Src activation was elevated at day 7 compared to wild-type mice. Both increased activation and temporal regulation of these signaling pathways may contribute to enhanced vascular growth in response to injury in this transgenic model of elevated vascular ROS.

  3. Association Between the Lateral Wall Thickness of the Maxillary Sinus and the Dental Status: Cone Beam Computed Tomography Evaluation

    International Nuclear Information System (INIS)

    Assessment of the lateral wall thickness of the maxillary sinus is very important in decision making for many surgical interventions. The association between the thickness of the lateral wall of the maxillary sinus and the dental status is not well identified. To compare the thickness of the lateral wall of the maxillary sinus in individuals with and without teeth to determine if extraction of the teeth can lead to a significant reduction in the thickness of the maxillary sinus lateral wall or not. In a retrospective study on fifty patients with an edentulous space, the thickness of the lateral wall of the maxillary sinus,one centimeter above the sinus floor in the second premolar (P2), first molar (M1) and second molar (M2) areas was determined by cone beam computed tomography scans(CBCTs) and a digital ruler in Romexis F software (Planmeca Romexis 2.4.2.R) and it was compared with values measured in fifty dentated individuals. Three way analysis of variance was applied for comparison after confirmation of the normal distribution of data. The mean of the wall thickness in each of these points was lower in patients with edentulous spaces; however it was not significant. There was no association between gender and the thickness of the lateral wall of the maxillary sinus, but location was associated with different thicknesses. The differences in the thickness based on the location and dental status necessitates assessment of the wall thickness of the maxillary sinus in addition to the current evaluation of bone thickness between the sinus floor and the edentulous crest before maxillary sinus surgery

  4. 彩色多普勒超声评价颈总动脉壁厚度及血管阻力指数与代谢综合征患者急性心肌梗死发生的关系%Correlation between wall thickness or resistance index of common carotid artery and acute myocardial infarction development in patients with metabolic syndrome

    Institute of Scientific and Technical Information of China (English)

    廖继安; 孙政; 沈丹; 张化诚

    2011-01-01

    Objective To evaluate the efficacy of acute myocardial infarction (AMI) prediction in patients with metabolic syndrome ( MS) by color Doppler ultrasound. Methods Of all 102 cases, MS patients with AMI were 57 cases and 45 cases had no AMI. Intima-media thickness ( IMT) , adventitial thickness ( AT) and resistance index ( RI) of common carotid artery ( CCA) were measured in 102 patients with MS by color Doppler ultrasound. The relationships between CCA indexes and AMI development as well as AMI risk factors were analyzed. Results IMT and AT were increased in MS patients with AMI compared with those without AMI. There was significant correlation between development of AMI and IMT or AT (P < 0. 01, P <0. 05). The detection rates of IMT and AT were greater than RI in AMI group (P <0. 001) , while that of IMT was the greatest in the non-AMI group (P<0. 005). In AMI patients, IMT was correlated with systolic blood pressure, 2-hour postprandial blood sugar and fibrinogen ( FIB) positively correlated (r = 0. 830, r = 0. 835, r =0. 753 , respectively,P <0. 001) with high density lipoprotein cholesterol ( HDL-C)negatively (r = - 0. 840,P <0. 001). AT was positively correlated with FIB (r =0. 828 ,P <0. 001) , and negatively with HDL-C (r = - 0. 798 ,P <0. 001). RI was negatively correlated with HDL-C ( r = - 0. 671 ,P<0. 001) . Conclusion IMT and AT measurement in MS patients could increase accuracy of AMI incidence prediction,and provide ultra-acoustic evidence for early prevention and treatment measures.%目的 应用彩色多普勒超声评价颈总动脉壁厚度及血管阻力在预测代谢综合征(MS)患者急性心肌梗死(AMI)发生中的作用.方法 102例MS患者中合并AMI者57例,未合并AMI者45例.彩色多普勒超声观察颈总动脉(CCA)内膜-中层厚度(IMT)、外膜厚度(AT)及阻力指数(RI),分析评价上述指标与MS患者AMI发生的关系及与其他AMI危险因素间的相关性.结果 MS合并AMI组较MS

  5. Pharmacogenomics of estrogens on changes in carotid artery intima-medial thickness and coronary arterial calcification: Kronos Early Estrogen Prevention Study

    OpenAIRE

    Miller, VM; Jenkins, GD; Biernacka, JM; Heit, JA; Huggins, GS; Hodis, HN.; Budoff, MJ; Lobo, RA; Taylor, HS; Manson, JE; Black, DM; Naftolin, F.; Mitchell Harman, S; de Andrade, M.

    2016-01-01

    © 2016 the American Physiological Society. Prior to the initiation of menopausal hormone treatment (MHT), genetic variations in the innate immunity pathway were found to be associated with carotid artery intima-medial thickness (CIMT) and coronary arterial calcification (CAC) in women (n = 606) enrolled in the Kronos Early Estrogen Prevention Study (KEEPS). Whether MHT might affect these associations is unknown. The association of treatment outcomes with variation in the same 764 candidate ge...

  6. Genetic polymorphisms associated with carotid artery intima-media thickness and coronary artery calcification in women of the Kronos Early Estrogen Prevention Study

    OpenAIRE

    Miller, Virginia M.; Petterson, Tanya M.; Elysia N Jeavons; Lnu, Abhinita S.; Rider, David N.; John A Heit; Cunningham, Julie M.; Huggins, Gordon S.; Hodis, Howard N.; Budoff, Matthew J.; Santoro, Nanette; Hopkins, Paul N.; Lobo, Rogerio A.; Manson, JoAnn E; Naftolin, Frederick

    2012-01-01

    Menopausal hormone treatment (MHT) may limit progression of cardiovascular disease (CVD) but poses a thrombosis risk. To test targeted candidate gene variation for association with subclinical CVD defined by carotid artery intima-media thickness (CIMT) and coronary artery calcification (CAC), 610 women participating in the Kronos Early Estrogen Prevention Study (KEEPS), a clinical trial of MHT to prevent progression of CVD, were genotyped for 13,229 single nucleotide polymorphisms (SNPs) with...

  7. Reduction in arterial wall strain with aggressive lipid-lowering therapy in patients with carotid artery disease

    International Nuclear Information System (INIS)

    Inflammation and biomechanical factors have been associated with the development of vulnerable atherosclerotic plaques. Lipid-lowering therapy has been shown to be effective in stabilizing them by reducing plaque inflammation. Its effect on arterial wall strain, however, remains unknown. The aim of the present study was to investigate the role of high- and low-dose lipid-lowering therapy using an HMG-CoA reductase inhibitor, atorvastatin, on arterial wall strain. Forty patients with carotid stenosis >40% were successfully followed up during the Atorvastatin Therapy: Effects on Reduction Of Macrophage Activity (ATHEROMA; ISRCTN64894118) Trial. All patients had plaque inflammation as shown by intraplaque accumulation of ultrasmall super paramagnetic particles of iron oxide on magnetic resonance imaging at baseline. Structural analysis was performed and change of strain was compared between high- and low-dose statin at 0 and 12 weeks. There was no significant difference in strain between the 2 groups at baseline (P=0.6). At 12 weeks, the maximum strain was significantly lower in the 80-mg group than in the 10-mg group (0.085±0.033 vs. 0.169±0.084; P=0.001). A significant reduction (26%) of maximum strain was observed in the 80-mg group at 12 weeks (0.018±0.02; P=0.01). Aggressive lipid-lowering therapy is associated with a significant reduction in arterial wall strain. The reduction in biomechanical strain may be associated with reductions in plaque inflammatory burden. (author)

  8. Fully automated segmentation and tracking of the intima media thickness in ultrasound video sequences of the common carotid artery.

    Science.gov (United States)

    Ilea, Dana E; Duffy, Caoimhe; Kavanagh, Liam; Stanton, Alice; Whelan, Paul F

    2013-01-01

    The robust identification and measurement of the intima media thickness (IMT) has a high clinical relevance because it represents one of the most precise predictors used in the assessment of potential future cardiovascular events. To facilitate the analysis of arterial wall thickening in serial clinical investigations, in this paper we have developed a novel fully automatic algorithm for the segmentation, measurement, and tracking of the intima media complex (IMC) in B-mode ultrasound video sequences. The proposed algorithm entails a two-stage image analysis process that initially addresses the segmentation of the IMC in the first frame of the ultrasound video sequence using a model-based approach; in the second step, a novel customized tracking procedure is applied to robustly detect the IMC in the subsequent frames. For the video tracking procedure, we introduce a spatially coherent algorithm called adaptive normalized correlation that prevents the tracking process from converging to wrong arterial interfaces. This represents the main contribution of this paper and was developed to deal with inconsistencies in the appearance of the IMC over the cardiac cycle. The quantitative evaluation has been carried out on 40 ultrasound video sequences of the common carotid artery (CCA) by comparing the results returned by the developed algorithm with respect to ground truth data that has been manually annotated by clinical experts. The measured IMT(mean) ± standard deviation recorded by the proposed algorithm is 0.60 mm ± 0.10, with a mean coefficient of variation (CV) of 2.05%, whereas the corresponding result obtained for the manually annotated ground truth data is 0.60 mm ± 0.11 with a mean CV equal to 5.60%. The numerical results reported in this paper indicate that the proposed algorithm is able to correctly segment and track the IMC in ultrasound CCA video sequences, and we were encouraged by the stability of our technique when applied to data captured under

  9. Targeting novel antigens in the arterial wall in thromboangiitis obliterans.

    Directory of Open Access Journals (Sweden)

    Murat Akkus

    2010-06-01

    Full Text Available Thromboangiitis obliterans is an inflammatory disease possibly resulting from cigarette smoking as a primary etiologic factor, perhaps as a delayed type of hypersensitivity or toxic angiitis. As little is known about the pathogenesis of the disease, we aimed to determine novel antigens that might be responsible from the local inflammatory reactions and structural changes observed in this disease. An indirect immunoperoxidase technique is used to examine the tissue samples obtained from the dorsalis pedis artery of affected individuals with twenty monoclonal antibodies. Among these several antigens which are not previously reported in TAO like CD34, CD44 and CD90 were determined in the tissue samples examined. On the other hand, many other antigens like cytokine/chemokine receptors, several enzymes and leukocyte/lymphocyte antigens were lacking giving some clues about the local pathological reactions. We briefly discussed our findings for several critical antigens those first described in the present work, possibly having roles in the development of the disease. Expression of the CD90/CD11c receptor/ligand pair seems to play an important role in mononuclear cell recruitment to the damage site. Vascular invasion of not only tunica intima but also the tunica media in affected vessels is clearly demonstrated using endothelial cell specific antigens.

  10. Normal flow-mediated vasodilatation of the brachial artery and carotid artery intima-media thickness in subclinical hypothyroidism

    Directory of Open Access Journals (Sweden)

    M.D. Cabral

    2009-05-01

    Full Text Available Subclinical hypothyroidism (SHT is a disease for which exact therapeutic approaches have not yet been established. Previous studies have suggested an association between SHT and coronary heart disease. Whether this association is related to SHT-induced changes in serum lipid levels or to endothelial dysfunction is unclear. The aim of this study was to determine endothelial function measured by the flow-mediated vasodilatation of the brachial artery and the carotid artery intima-media thickness (IMT in a group of women with SHT compared with euthyroid subjects. Triglycerides, total cholesterol, HDL-C, LDL-C, apoprotein A (apo A, apo B, and lipoprotein(a were also determined. Twenty-one patients with SHT (mean age: 42.4 ± 10.8 years and mean thyroid-stimulating hormone (TSH levels: 8.2 ± 2.7 µIU/mL and 21 euthyroid controls matched for body mass index, age and atherosclerotic risk factors (mean age: 44.2 ± 8.5 years and mean TSH levels: 1.4 ± 0.6 µIU/mL participated in the study. Lipid parameters (except HDL-C and apo A, which were lower and IMT values were higher in the common carotid and carotid bifurcation of SHT patients with positive serum thyroid peroxidase antibodies (TPO-Ab (0.62 ± 0.2 and 0.62 ± 0.16 mm for the common carotid and carotid bifurcation, respectively when compared with the negative TPO-Ab group (0.55 ± 0.24 and 0.58 ± 0.13 mm, for common carotid and carotid bifurcation, respectively. The difference was not statistically significant. We conclude that minimal thyroid dysfunction had no adverse effects on endothelial function in the population studied. Further investigation is warranted to assess whether subclinical hypothyroidism, with and without TPO-Ab-positive serology, has any effect on endothelial function.

  11. Multiscale, structure-based modeling for the elastic mechanical behavior of arterial walls.

    Science.gov (United States)

    Stylianopoulos, Triantafyllos; Barocas, Victor H

    2007-08-01

    Passive elastic behavior of arterial wall remains difficult to model. Although phenomenological and structural models exist, the question of how the three-dimensional network structure of the collagen in the artery determines its mechanical properties is still open. A model is presented that incorporates a collagen network as well as the noncollagenous material that comprise the artery. The collagen architecture is represented as a network of interconnected fibers, and a neo-Hookean constitutive equation is used to describe the contribution of the noncollagenous matrix. The model is multiscale in that volume-averaging theory is applied to the collagen network, and it is structural in that parameters of the microstructure of the collagen network were considered instead of a macroscopic constitutive law. The computational results provided a good fit to published experimental data for decellularized porcine carotid arteries. The model predicted increased circumferential compliance for increased axial stretch, consistent with previously published reports, and a relatively small sensitivity to open angle. Even at large extensions, the model predicted that the noncollagenous matrix would be in compression, preventing collapse of the collagen network. The incorporation of fiber-fiber interactions led to an accurate model of artery wall behavior with relatively few parameters. The counterintuitive result that the noncollagenous component is in compression during extension and inflation of the tissue suggests that the collagen is important even at small strains, with the noncollagenous components supporting the network, but not resisting the load directly. More accurate representation of the microstructure of the artery wall is needed to explore this issue further. PMID:17655483

  12. The Boiler Tube Wall Thickness Quantitative Evaluation Fusing the Magnetic and Ultrasonic Technique

    Institute of Scientific and Technical Information of China (English)

    SONG Xiaochun; HUANG Songling; ZHAO Daxing

    2006-01-01

    Wall thickness is always a key index for boiler tube inspection in power plant, in order to improve the inspection efficiency and accuracy, a new method fusing the magnetic and ultrasonic technique was proposed. The magnetic technique was used to do full inspection and locate the flaws, and the ultrasonic was employed to implement further quantitative inspection accurately. After comparing the precision of the polynomial, exponential and logarithmic function, the polynomial model was selected to fit the relations between the wall thickness and the peak value of magnetic signals, and the data measured by ultrasonic thickness meter was used to calibrate the model parameters online, the defect depth can be sized quickly. The experimental results demonstrate that the model used in this system has better accuracy than the statistics relation model clearly, and it is also suitable for defect evaluation real-time. Moreover, it is unnecessary to have much more experimental data for the curve fitting technology, so it has better practicability than the other methods.

  13. OPTIMIZATION OF INHOMOGENEOUS THICK-WALLED SPHERICAL SHELL IN THE TEMPERATURE FIELD

    Directory of Open Access Journals (Sweden)

    Andreev Vladimir Igorevich

    2012-12-01

    Full Text Available The authors consider the central symmetric problem of the theory of elasticity of inhomogeneous bodies for thick-walled spheres exposed to the external pressure in a stationary temperature field. The essence of the inverse problem lies in the identification of such dependence of the elastic modulus on the radius whereby the stress state of the sphere is the same as the pre-set one. Maximal stresses in thick-walled shells exposed to internal or external pressures occur in the proximity to the internal contour. Thus, destruction in this area is initiated upon the achievement of the limit state, while the rest of the shell is underused. The essence of the problem solved in the paper is the following. The problems are solved using the simultaneous exposure to forces and temperature loads.The two theories of strength are considered at once: a maximum normal stress theory and a maximum shear stress theory. It is proven that according to the first theory maximum stresses in an inhomogeneous shell are 1.35 times smaller than those in the homogeneous shell. The stress reduction rate equals to 2.5, if the maximum shear stress theory is employed. Thus, the introduction of artificial inhomogeneity leads to the optimization of shells by reducing their thickness or increasing loads.

  14. EFFECT OF WORKPIECE VOLUME ON SHELL WALL THICKNESS REDUCTION IN RAPID CASTING OF ALUMINUM USING THREE-DIMENSIONAL PRINTING

    Directory of Open Access Journals (Sweden)

    Rupinder Singh

    2012-12-01

    Full Text Available The purpose of the present work is to study the effect of workpiece volume on reducing the shell wall thickness in rapid shell casting based upon three-dimensional printing (3DP technology, and to evaluate the dimensional accuracy and mechanical properties of aluminum (Al castings obtained as per the ISO standard UNIEN 20286-I (1995. Starting from the identification of component/benchmark, castings of different volumes (corresponding to workpieces of Φ60 mm, Φ50 mm and Φ40 mm were produced with different shell wall thicknesses. Measurements on a coordinate measuring machine (CMM allowed the calculation of the dimensional tolerances of the castings produced. Some important mechanical properties were also compared to verify the suitability of the castings. The research proved that having a shell wall thickness with a value less than that recommended (12 mm is more suitable from a dimensional accuracy and economic point of view (irrespective of the workpiece volume within the given selected range. All the castings produced with different shell thicknesses are acceptable as per the ISO standard. The results of the study suggest that workpiece volume has an unnoticeable effect on reducing the shell wall thickness for the selected range of volumes of casting. Furthermore, the hardness of castings produced is almost same for all shell wall thicknesses, from 12 mm to 1 mm. The results are supported by cooling (time-temperature curves, which show unnoticeable changes in the rate of heat transfer at different shell wall thicknesses. Keeping in mind the cost effectiveness of the process, one (1 mm shell wall thickness has been recommended for the production of castings. For a 1 mm shell wall thickness, the production cost and time are reduced by 67.38% and 44.87% (for Φ60 mm workpieces, 64.51% and 44.62% (for Φ50 mm workpieces, and 69.50% and 59.64% (for Φ40 mm workpieces, respectively.

  15. MDCT assessment of airway wall thickness in COPD patients using a new method: correlations with pulmonary function tests

    Energy Technology Data Exchange (ETDEWEB)

    Achenbach, Tobias; Weinheimer, Oliver; Schmitt, Sabine; Freudenstein, Daniela; Kunz, Richard Peter; Dueber, Christoph [Johannes Gutenberg University, Department of Diagnostic and Interventional Radiology, Mainz (Germany); Biedermann, Alexander; Buhl, Roland [Johannes Gutenberg University, IIIrd Department of Internal Medicine - Pneumology, Mainz (Germany); Goutham, Edula [Astra Zeneca, Lund (Sweden); Heussel, Claus Peter [Thoraxklinik, University Hospital Heidelberg, Diagnostic and Interventional Radiology, Heidelberg (Germany)

    2008-12-15

    Quantitative assessment of airway-wall dimensions by computed tomography (CT) has proven to be a marker of airway-wall remodelling in chronic obstructive pulmonary disease (COPD) patients. The objective was to correlate the wall thickness of large and small airways with functional parameters of airflow obstruction in COPD patients on multi-detector (MD) CT images using a new quantification procedure from a three-dimensional (3D) approach of the bronchial tree. In 31 patients (smokers/COPD, non-smokers/controls), we quantitatively assessed contiguous MDCT cross-sections reconstructed orthogonally along the airway axis, taking the point-spread function into account to circumvent over-estimation. Wall thickness and wall percentage were measured and the per-patient mean/median correlated with FEV1 and FEV1%. A median of 619 orthogonal airway locations was assessed per patient. Mean wall percentage/mean wall thickness/median wall thickness in non-smokers (29.6%/0.69 mm/0.37 mm) was significantly different from the COPD group (38.9%/0.83 mm/0.54 mm). Correlation coefficients (r) between FEV1 or FEV1% predicted and intra-individual means of the wall percentage were -0.569 and -0.560, respectively, with p<0.001. Depending on the parameter, they were increased for airways of 4 mm and smaller in total diameter, being -0.621 (FEV1) and -0.537 (FEV1%) with p < 0.002. The wall thickness was significantly higher in smokers than in non-smokers. In COPD patients, the wall thickness measured as a mean for a given patient correlated with the values of FEV1 and FEV1% predicted. Correlation with FEV1 was higher when only small airways were considered. (orig.)

  16. MDCT assessment of airway wall thickness in COPD patients using a new method: correlations with pulmonary function tests

    International Nuclear Information System (INIS)

    Quantitative assessment of airway-wall dimensions by computed tomography (CT) has proven to be a marker of airway-wall remodelling in chronic obstructive pulmonary disease (COPD) patients. The objective was to correlate the wall thickness of large and small airways with functional parameters of airflow obstruction in COPD patients on multi-detector (MD) CT images using a new quantification procedure from a three-dimensional (3D) approach of the bronchial tree. In 31 patients (smokers/COPD, non-smokers/controls), we quantitatively assessed contiguous MDCT cross-sections reconstructed orthogonally along the airway axis, taking the point-spread function into account to circumvent over-estimation. Wall thickness and wall percentage were measured and the per-patient mean/median correlated with FEV1 and FEV1%. A median of 619 orthogonal airway locations was assessed per patient. Mean wall percentage/mean wall thickness/median wall thickness in non-smokers (29.6%/0.69 mm/0.37 mm) was significantly different from the COPD group (38.9%/0.83 mm/0.54 mm). Correlation coefficients (r) between FEV1 or FEV1% predicted and intra-individual means of the wall percentage were -0.569 and -0.560, respectively, with p<0.001. Depending on the parameter, they were increased for airways of 4 mm and smaller in total diameter, being -0.621 (FEV1) and -0.537 (FEV1%) with p < 0.002. The wall thickness was significantly higher in smokers than in non-smokers. In COPD patients, the wall thickness measured as a mean for a given patient correlated with the values of FEV1 and FEV1% predicted. Correlation with FEV1 was higher when only small airways were considered. (orig.)

  17. Ultrasound evaluation of intima media thickness of carotid arteries in dialysis patients and correlation with proposed risk factors

    Directory of Open Access Journals (Sweden)

    Damjanović Tatjana

    2003-01-01

    Full Text Available Atherosclerosis is significant risk factor for cardiovascular morbidity and mortality in dialysis patients. Aim of the study was ultrasound evaluation of intima media thickness on carotid arteries (as a marker of atherosclerosis, in dialysis patients and its correlation with proposed risk factors. Intima media thickness was measured in 45 dialysis patients with no signs of cardiovascular diseases (15 on peritoneal dialysis, group I,30 on hemodialysis, group II and 20 healthy controls. The mean carotid artery intima media thickness was significantly higher in dialysis patients than in control group. According to intima media thickness, dialysis patients were divided in group A (patient with intima media thickness less or equal 0,720 mm and group B (intima media thickness higher then 0,720mm. Intima media thickness in bout group was correlated with proposed risk factors. In group A there was not significant correlation of intima media thickness with risk factors. In group B significant correlation have been found between intima media thickness and LDL, VLDL cholesterol, body mass index and systolic, diastolic and mean blood pressure. Although atherosclerosis was not the only cause for cardiovascular morbidity and mortality, it has a dominant role in dialysis patients. Augmented intima media thickness could be early marker of atherosclerosis. The risk factors of great influence on intima media thickness are lipid disturbances, obesity and hypertension.

  18. Adaptive ultrasonic measurement of blood vessel diameter and wall thickness: theory and experimental results.

    Science.gov (United States)

    Rafii, K; Jaffe, J S

    1998-01-01

    An adaptive ultrasonic technique for measuring blood vessel diameter and wall thickness is presented. This technique allows one to use a target-specific transmitted waveform/receiver filter to obtain a larger signal-to-noise ratio (SNR) in the received signal than conventional techniques. Generally, SNR of a received wave increases as the intensity of the transmit wave increases; however, because of the FDA limitations placed on the amount of transmit energy, it is important to be able to make the most efficient use of the energy that is available to obtain the best possible SNR in the received signal. Adaptive ultrasonic measurement makes the most efficient use of the energy that is available by placing the maximum amount of energy in the largest target scattering mode. This results in more energy backscatter from a given target, which leads to a higher SNR in the received waveform. Computer simulations of adaptive ultrasonic measurement of blood vessel diameter show that for a SNR of 0 dB in the transmitted waveform, the standard deviation of the diameter measurements for a custom-designed transmitted waveform is about two orders of magnitude less than the standard deviation of the diameter measurements using more conventional waveforms. Diameter and wall thickness measurement experiments were performed on a latex tube and a bovine blood vessel using both custom-made and conventionally used transmitted waveforms. Results show that the adaptively designed waveform gives a smaller uncertainty in the measurements. The adaptive ultrasonic blood vessel diameter and wall thickness measuring technique has potential applications in examining vessels which are either too deep inside the body or too small for conventional techniques to be used, because of the low SNR in the received signal. PMID:18244211

  19. Ultrasound Thickness of Bladder Wall in Continent and Incontinent Women and Its Correlation with Cystometry

    Directory of Open Access Journals (Sweden)

    Edney Norio Otsuki

    2014-01-01

    Full Text Available Objective. To compare bladder wall thickness in two kinds of urinary incontinent women—stress urinary incontinence (SUI and overactive bladder (OAB with urodynamic detrusor overactivity (DO, and to compare them with continent patients by ultrasound, also, correlate with cystometric results in incontinent women. Methods. 91 women were divided into the following groups: continent (n=31, SUI (n=30, and DO (n=30 groups after clinical evaluation and urodynamic test (only in incontinent women. Transvaginal ultrasound was performed to the bladder wall thickness (BWT measurement. The mean of BWT was calculated and data were analyzed with ANOVA and Turkey’s multiple comparison tests. Pearson’s correlation coefficient (r was used to compare two variables. Receiver operating characteristic (ROC curve was performed to study BWT as a diagnostic parameter. Results. BWT in DO group was significantly higher than that in the other groups (P<0.005. A moderate positive correlation was found between BWT and maximum bladder pressure during involuntary bladder contraction. There was no difference in BWT between SUI and continent groups. DO group had lower first desire to void and cystometric capacity. Maximum bladder pressure at detrusor contraction had a moderate positive correlation with BWT. The ROC revealed an area under the curve of 0.962 (95% CI, 0.90–1.01. Conclusions. DO patients have increased bladder wall thickness, lower first desire to void, and lower cystometric capacity. There was a moderate correlation between BWT and maximum bladder pressure during involuntary bladder contraction.

  20. Full-thickness chest wall resection for locally recurrent breast cancer

    Directory of Open Access Journals (Sweden)

    Friedel, Godehard

    2005-08-01

    Full Text Available Aim: In spite of available recommendations, therapeutic procedures of locally recurrent breast cancer are very different. In a retrospective study, the possibilities and results of complete, full-thickness chest wall resection are presented.Methods: Between 1985 and 2004, 51 women underwent complete, full-thickness chest wall resection with primary coverage. Primary surgical therapy of breast cancer had been mastectomy in 88%. Median age of patients undergoing surgery for a local recurrence was 57 (29 - 81 years. The median interval between surgery of the primary tumour and of the local recurrence was 70.3 (10.7 - 327.2 months; median follow-up was 29.4 (1.8 - 230.9 months. 40 (78.4% patients required rib resections, 15 (29.4% of them in combination with partial sternal resection. In 4 (7.8% patients complete and in 7 (13.7% patients partial sternal resection without additional rib resection were performed.Coverage was mainly realized using latissimus dorsi myocutaneous flaps (n=44; 86.3%. Survival rates were calculated by means of the Kaplan-Meier method, the relative risk using univariate and multivariate Cox-regression analysis.Results: In the total collective, cumulative 5-, 10- and 15-year survival (YS rates were 39%, 31% and 23%, respectively, median survival 46.4 months. R0 resection was associated with a 5-YS of 42%. Prognostic factors were age at the time of primary surgery, disease-free interval and tumour invasion of bony structures. Mortality was 2%, morbidity 35%.Conclusion: Full-thickness chest wall resection of locally recurrent breast cancer is possible in almost any patient when performed by a team of thoracic and plastic surgeons. Only radical resection provides good long-term results with low mortality and morbidity.

  1. Calculation of creep deformation and stresses in thick-walled pipes

    International Nuclear Information System (INIS)

    Heat exchangers for methane reforming processes which are installed in a helium-cooled high-temperature reactor may experience temperatures up to 800 or 9500C. At such temperatures, creep in metallic structures is a phenomenon that requires full attention. The report explains methods of calculating stresses and creep deformation in thick-walled pipes subjected to pressure loads and superimposed axial loads. Norton's creep law is taken as the basic descriptive equation. The calculation methods applied are both exact (continuum mechanics) and approximative. The results of both calculation types for a series of examples are compared and discussed. (orig.)

  2. Joining of bulk metallic glass to brass by thick-walled cylinder explosion

    International Nuclear Information System (INIS)

    This paper reports the development of a thick-walled cylinder explosion technique to weld a typical Zr-based bulk metallic glass (Vitreloy 1 (Vit 1)) to a commercial Cu-based crystalline alloy (brass). It is shown that a strong metallurgical bonding between the Vit 1 and the brass is achieved, which is due to significant atomic diffusion across the welding interface and shock wave propagation in the weldment. The dissimilar joining of the noncrystalline to crystalline alloy extends the application of bulk metallic glasses as structural and functional materials

  3. Thick-Walled Cylinder Theory Applied on a Conical Wedge Anchorage

    DEFF Research Database (Denmark)

    Bennitz, Anders; Grip, Niklas; Schmidt, Jacob Wittrup

    2011-01-01

    Conical wedge anchorages are frequently used to anchor steel tendons in prestressing applications within the construction industry. To replace the steel tendons with non-corrosive and low weight FRPs (Fiber Reinforced Polymers), the different mechanical interactions between the steel and FRPs call...... for further development of the anchorage.In this paper, we derive and examine an analytical model for the internal stresses and strains within the anchorage for a prescribed presetting distance. This model is derived from the theory of thick walled cylinders under the assumptions regarding plane...

  4. IFE thick liquid wall chamber dynamics: Governing mechanisms andmodeling and experimental capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Raffray, A.R.; Meier, W.; Abdel-Khalik, S.; Bonazza, R.; Calderoni, P.; Debonnel, C.S.; Dragojlovic, Z.; El-Guebaly, L.; Haynes,D.; Latkowski, J.; Olson, C.; Peterson, P.F.; Reyes, S.; Sharpe, P.; Tillack, M.S.; Zaghloul, M.

    2005-01-24

    For thick liquid wall concepts, it is important to understand the different mechanisms affecting the chamber dynamics and the state of the chamber prior to each shot a compared with requirements from the driver and target. These include ablation mechanisms, vapor transport and control, possible aerosol formation, as well as protective jet behavior. This paper was motivated by a town meeting on this subject which helped identify the major issues, assess the latest results, review the capabilities of existing modeling and experimental facilities with respect to addressing remaining issues, and helping guide future analysis and R&D efforts; the paper covers these exact points.

  5. Increased wall thickness using ultrasonography is associated with inflammation in an animal model of experimental colitis

    Directory of Open Access Journals (Sweden)

    Lied GA

    2012-10-01

    Full Text Available Gülen Arslan Lied,1 Anne Marita Milde,2 Kim Nylund,1,3 Maja Mujic,1 Tore Grimstad,1,4 Trygve Hausken,1,3 Odd Helge Gilja1,31Institute of Medicine, University of Bergen, Norway; 2Department of Biological and Medical Psychology, University of Bergen, Norway; 3National Centre for Ultrasound in Gastroenterology, Haukeland University Hospital, Bergen, Norway; 4Division of Gastroenterology, Stavanger University Hospital, Stavanger, NorwayAbstract: Experimentally induced colitis is used in animals to investigate pathophysiological mechanisms in inflammatory bowel disease. When following disease course and treatment effects, it should be possible to perform repeated measurements without harming the animals. This pilot study was performed to investigate whether transabdominal ultrasound using a clinical scanner could be used on rats to demonstrate bowel inflammation in an experimental colitis model. Colitis was induced by either 5% dextran sodium sulfate (DSS in drinking water for 7 days or a single dose of intracolonic trinitrobenzene sulfonic acid (TNBS. Using ultrasonography, wall thickness of distal colon, cecum, and small bowel was recorded prior to and after DSS, and prior to, 2, and 7 days after TNBS. Blood (tumor necrosis factor [TNF]-alpha and fecal samples (HemoFEC occult blood were taken from each group on the same days as sonography. Thereafter, rats were killed and specimens for histology were taken. Wall thickness of distal colon, not of cecum or small bowel, increased significantly after 7 days of DSS, and wall thickness of both distal colon and small bowel increased on day 2 and 7 after TNBS. TNF-alpha increased after 7 days in the latter group only. There was a significant correlation between ultrasonographic measurements and combined histology score of distal colon in the DSS group. HemoFEC was also positive in accordance with sonographic and histological features. Increased intestinal wall thickness in response to both DSS- and TNBS

  6. Investigation of torsional vibrations in thick walled hollow poroelastic cylinder using Biot's extension theory

    Indian Academy of Sciences (India)

    Malla Reddy Perati; Rajitha Gurijala

    2015-09-01

    This paper deals with the study of torsional vibrations of thick walled hollow poroelastic cylinder using Biot's extension theory. Considering the boundaries to be stress free, the frequency equation is obtained in the presence of dissipation which is transcendental and complex valued in nature. In the special case of poroelastic thin shell, frequency equation is separated into two real valued equations giving propagation velocity and attenuation coefficient. From the numerical results in the case of sandy sediment, it is clear that the values of propagation velocity are, in general, less than that of attenuation coefficient.

  7. Exact and numerical elastodynamic solutions for thick-walled functionally graded cylinders subjected to pressure shocks

    Energy Technology Data Exchange (ETDEWEB)

    Shariyat, M., E-mail: m_shariyat@yahoo.co [Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Pardis Street, Molla-Sadra Avenue, Vanak Square, P.O. Box: 19395-1999, Tehran 19991 43344 (Iran, Islamic Republic of); Nikkhah, M.; Kazemi, R. [Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Pardis Street, Molla-Sadra Avenue, Vanak Square, P.O. Box: 19395-1999, Tehran 19991 43344 (Iran, Islamic Republic of)

    2011-02-15

    In the present paper, analytical and numerical elastodynamic solutions are developed for long thick-walled functionally graded cylinders subjected to arbitrary dynamic and shock pressures. Both transient dynamic response and elastic wave propagation characteristics are studied in these non-homogeneous structures. Variations of the material properties across the thickness are described according to both polynomial and power law functions. A numerically consistent transfinite element formulation is presented for both functions whereas the exact solution is presented for the power law function. The FGM cylinder is not divided into isotropic sub-cylinders. An approach associated with dividing the dynamic radial displacement expression into quasi-static and dynamic parts and expansion of the transient wave functions in terms of a series of the eigenfunctions is employed to propose the exact solution. Results are obtained for various exponents of the functions of the material properties distributions, various radius ratios, and various dynamic and shock loads.

  8. Creep damage evaluation of thick-walled spheres using a long-term creep constitutive model

    International Nuclear Information System (INIS)

    This paper describes a numerical model developed for the computation of creep damages in a thick-walled sphere subjected to an internal pressure and a thermal gradient. The model predicts the creep damage histories during the life of the sphere, owing to variations in stresses with time and through-thickness variations. The creep damage fraction is based on the Robinson's linear life fraction damage rule, which has been incorporated in a nonlinear time-dependent stress analysis. Following the stress histories, the effective stress histories are obtained and the creep damages are calculated and summed during the life of the sphere. The material long-term creep properties up to the rupture and creep rupture data are defined by the Θ projection concept. The damage histories up to 38 years are calculated and the results show that the maximum damages are always located at the inner surface of the sphere, while the outer surface of the vessel sustains minimum damages

  9. Automated image segmentation and registration of vessel wall MRI for quantitative assessment of carotid artery vessel wall dimensions and plaque composition

    NARCIS (Netherlands)

    Klooster, Ronald van 't

    2014-01-01

    The main goal of this thesis was to develop methods for automated segmentation, registration and classification of the carotid artery vessel wall and plaque components using multi-sequence MR vessel wall images to assess atherosclerosis. First, a general introduction into atherosclerosis and differe

  10. A Crucial Role of Glycoprotein VI for Platelet Recruitment to the Injured Arterial Wall In Vivo

    OpenAIRE

    Massberg, Steffen; Gawaz, Meinrad; Grüner, Sabine; Schulte, Valerie; Konrad, Ildiko; Zohlnhöfer, Dietlind; Heinzmann, Ulrich; Nieswandt, Bernhard

    2003-01-01

    Platelet adhesion and aggregation at sites of vascular injury is crucial for hemostasis but may lead to arterial occlusion in the setting of atherosclerosis and precipitate diseases such as myocardial infarction. A current hypothesis suggests that platelet glycoprotein (GP) Ib interaction with von Willebrand factor recruits flowing platelets to the injured vessel wall, where subendothelial fibrillar collagens support their firm adhesion and activation. However, so far this hypothesis has not ...

  11. Arterial wall stiffness in patients with essential hypertension at young age

    Directory of Open Access Journals (Sweden)

    Kolesnik E.L.

    2014-11-01

    Full Text Available Research objective was investigating arterial wall stiffness in patients with hypertension at young age and assessing the relationship between subclinical target organs damage and ambulatory blood pressure monitoring (ABPM parameters. 30 male patients aged 18-35 years with essential hypertension stage I and II, hypertension 1 and 2nd grade were surveyed. The examination included general clinical methods, echocardiography, ABPM and suprasystolic sfigmography. It was found that the pulse wave velocity (PWVao (r = 0,557 p <0,01, central aortic blood pressure (SBPao (r = 0,492 p <0,01 and augmentation index (AIxao (r = 0,489 p <0.01 significantly increased with the pa¬tients’ age. Abdominal obesity (r = 0,566 p <0,01 and BMI (r = 0,599 p <0,01 impacted on the PWVao acceleration. Increasing of the left ventricular mass index (LVMI is highly associated with SBPao (r = 0,506 p <0,05 and PWVao (r = 0,434 p <0,05. According to ABPM the most significant correlation with arterial wall stiffness parameters demon¬strated diastolic blood pressure (DBP daytime level (AIxao (r = 0,418 p <0,01, with PWVao (r = 0,699 p <0.01 and SBPao (r = 0,695 p <0,01. Thus, age, excessive body weight and obesity should be considered as unfavorable factors that worsen arterial wall stiffness in patients with hypertension at the age before 35 years. Increase of DBP levels especially during the day causes maximum negative impact on the arterial wall stiffness parameters according to ABPM. Increased SBPao and PWVao in patients with hypertension at a young age are associated with increased left ventricular mass index.

  12. Effect of bladder wall thickness on miniature pneumatic artificial muscle performance.

    Science.gov (United States)

    Pillsbury, Thomas E; Kothera, Curt S; Wereley, Norman M

    2015-10-01

    Pneumatic artificial muscles (PAMs) are actuators known for their high power to weight ratio, natural compliance and light weight. Due to these advantages, PAMs have been used for orthotic devices and robotic limbs. Small scale PAMs have the same advantages, as well as requiring greatly reduced volumes with potential application to prostheses and small scale robotics. The bladder of a PAM affects common actuator performance metrics, specifically: blocked force, free contraction, hysteresis, and dead-band pressure. This paper investigates the effect that bladder thickness has on static actuation performance of small scale PAMs. Miniature PAMs were fabricated with a range of bladder thicknesses to quantify the change in common actuator performance metrics specifically: blocked force, free contraction, and dead-band pressure. These PAMs were then experimentally characterized in quasi-static conditions, where results showed that increasing bladder wall thickness decreases blocked force and free contraction, while dead-band pressure increases. A nonlinear model was then applied to determine the structure of the stress-strain relationship that enables accurate modeling and the minimum number of terms. Two nonlinear models are compared and the identified parameters are analyzed to study the effect of the bladder thickness on the model. PMID:26414160

  13. Changes in pulmonary arterial wall mechanical properties and lumenal architecture with induced vascular remodeling

    Science.gov (United States)

    Molthen, Robert C.; Heinrich, Amy E.; Haworth, Steven T.; Dawson, Christopher A.

    2004-04-01

    To explore and quantify pulmonary arterial remodeling we used various methods including micro-CT, high-resolution 3-dimensional x-ray imaging, to examine the structure and function of intact pulmonary vessels in isolated rat lungs. The rat is commonly used as an animal model for studies of pulmonary hypertension (PH) and the accompanying vascular remodeling, where vascular remodeling has been defined primarily by changes in the vessel wall composition in response to hypertension inducing stimuli such as chronic hypoxic exposure (CHE) or monocrotaline (MCT) injection. Little information has been provided as to how such changes affect the vessel wall mechanical properties or the lumenal architecture of the pulmonary arterial system that actually account for the hemodynamic consequences of the remodeling. In addition, although the link between primary forms of pulmonary hypertension and inherited genetics is well established, the role that genetic coding plays in hemodynamics and vascular remodeling is not. Therefore, we are utilizing Fawn-Hooded (FH), Sprague-Dawley (SD) and Brown Norway (BN)rat strains along with unique imaging methods to parameterize both vessel distensibility and lumenal morphometry using a principal pulmonary arterial pathway analysis based on self-consistency. We have found for the hypoxia model, in addition to decreased body weight, increased hematocrit, increased right ventricular hypertrophy, the distensibility of the pulmonary arteries is shown to decrease significantly in the presence of remodeling.

  14. [Hematoma of the abdominal wall. A case report: pitfall of Seldinger method via femoral artery].

    Science.gov (United States)

    Hiramatsu, Hisaya; Sugiura, Yasushi; Takeda, Ririko; Nanba, Hiroki

    2009-02-01

    We reported a case of an abdominal wall hematoma which caused by Seldinger method via the femoral artery. A 48-year-old female, suffered from direct carotid cavernous fistula, was treated by transfemoral transvenous embolization (TVE). The whole procedure was completed without difficulty except minor resistance of guide wire manipulation during left femoral artery catheterization. Four hours later, the patient became hypotensive and showed the sign of impending shock without definitive causes. Nine hours after the embolization a huge hematoma of the abdominal wall was found. It required the total 1200 m/ of blood transfusion before her blood pressure returned to normal. She recovered fully from this event and discharged uneventfully. There is a speculation that a deep circumflex iliac artery (DCIA) was injured with an angle-shaped guide wire and bled into the abdominal wall. And subsequent systemic heparinization prevented the coagulation process, resulting a large hematoma. Anatomically, an angle-shaped guide wire is easily able to migrate into DCIA. To prevent a vascular injury, it is very important to manipulate a guide wire under fluoroscopic control and to select a J-shaped guide wire instead of an angle-shaped one. PMID:19227158

  15. Effect of subcooling and wall thickness on pool boiling from downward-facing curved surfaces in water

    Energy Technology Data Exchange (ETDEWEB)

    El-Genk, M.S.; Glebov, A.G. [Univ. of New Mexico, Albuquerque, NM (United States)

    1995-09-01

    Quenching experiments were performed to investigate the effects of water subcooling and wall thickness on pool boiling from a downward-facing curved surface. Experiments used three copper sections of the same diameter (50.8 mm) and surface radius (148 mm), but different thickness (12.8, 20 and 30 mm). Local and average pool boiling curves were obtained at saturation and 5 K, 10 K, and 14 K subcooling. Water subcooling increased the maximum heat flux, but decreased the corresponding wall superheat. The minimum film boiling heat flux and the corresponding wall superheat, however, increased with increased subcooling. The maximum and minimum film boiling heat fluxes were independent of wall thickness above 20 mm and Biot Number > 0.8, indicating that boiling curves for the 20 and 30 thick sections were representative of quasi steady-state, but not those for the 12.8 mm thick section. When compared with that for a flat surface section of the same thickness, the data for the 12.8 mm thick section showed significant increases in both the maximum heat flux (from 0.21 to 0.41 MW/m{sup 2}) and the minimum film boiling heat flux (from 2 to 13 kW/m{sup 2}) and about 11.5 K and 60 K increase in the corresponding wall superheats, respectively.

  16. Non-Newtonian effects of blood on LDL transport inside the arterial lumen and across multi-layered arterial wall with and without stenosis

    Science.gov (United States)

    Deyranlou, Amin; Niazmand, Hamid; Sadeghi, Mahmood-Reza; Mesri, Yaser

    2016-06-01

    Blood non-Newtonian behavior on low-density lipoproteins (LDL) accumulation is analyzed numerically, while fluid-multilayered arteries are adopted for nonstenotic and 30%-60% symmetrical stenosed models. Present model considers non-Newtonian effects inside the lumen and within arterial layers simultaneously, which has not been examined in previous studies. Navier-Stokes equations are solved along with the mass transport convection-diffusion equations and Darcy’s model for species transport inside the luminal flow and across wall layers, respectively. Carreau model for the luminal flow and the modified Darcy equation for the power-law fluid within arterial layers are employed to model blood rheological characteristics, appropriately. Results indicate that in large arteries with relatively high Reynolds number Newtonian model estimates LDL concentration patterns well enough, however, this model seriously incompetent for regions with low WSS. Moreover, Newtonian model for plasma underestimates LDL concentration especially on luminal surface and across arterial wall. Therefore, applying non-Newtonian model seems essential for reaching to a more accurate estimation of LDL distribution in the artery. Finally, blood flow inside constricted arteries demonstrates that LDL concentration patterns along the stenoses inside the luminal flow and across arterial layers are strongly influenced as compared to the nonstenotic arteries. Additionally, among four stenosis severity grades, 40% stenosis is prone to more LDL accumulation along the post-stenotic regions.

  17. On what controls the spacing of spontaneous adiabatic shear bands in collapsing thick-walled cylinders

    Science.gov (United States)

    Lovinger, Zev; Rosenberg, Zvi; Rittel, Daniel

    2015-09-01

    Shear bands formation in collapsing thick walled cylinders occurs in a spontaneous manner. The advantage of examining spontaneous, as opposed to forced shear localization, is that it highlights the inherent susceptibility of the material to adiabatic shear banding without prescribed geometrical constraints. The Thick-Walled Cylinder technique (TWC) provides a controllable and repeatable technique to create and study multiple adiabatic shear bands. The technique, reported in the literature uses an explosive cylinder to create the driving force, collapsing the cylindrical sample. Recently, we developed an electro-magnetic set-up using a pulsed current generator to provide the collapsing force, replacing the use of explosives. Using this platform we examined the shear band evolution at different stages of formation in 7 metallic alloys, spanning a wide range of strength and failure properties. We examined the number of shear bands and spacing between them for the different materials to try and figure out what controls these parameters. The examination of the different materials enabled us to better comprehend the mechanisms which control the spatial distribution of multiple shear bands in this geometry. The results of these tests are discussed and compared to explosively driven collapsing TWC results in the literature and to existing analytical models for spontaneous adiabatic shear localization.

  18. Radial oscillations of highly stressed nonhomogenous, thick-walled cylindrical and spherical shells

    International Nuclear Information System (INIS)

    The present work investigates the infinitesimal breathing motions of spherical and long cylindrical shells of arbitrary wall thickness subject to a finite, axisymmetric deformation field caused by uniform internal and/or external pressures. A neo-Hookean material with a material constant varying continuously along the radial direction is used. The shell is first subject to finite, axisymmetric, static deformations and is then exposed to a secondary, axisymmetric, static deformations and is then exposed to a secondary, axisymmetric, dynamic displacement field. Based on the theory of small deformations superposed on large deformations, closed form expressions are obtained for the frequency of small oscillations about the highly prestressed state. Frequency versus initial deformation parameter curves are given for several nonhomogeneity functions and for various wall thicknesses. The softening or the hardening behaviors of the shells for varying prestress values are observed from these curves. When the frequency of breathing motions cease to be real valued, the superposed secondary motions are no larger periodic. Thus, the critical value of the prestress causing instability is defined as the one which corresponds to zero frequency. It is seen that when the nonhomogeneity parameters are taken zero, the known results of the homogeneous case are obtained. Although the material is assumed to be incompressible, the theory is general enough to include compressible materials. However, in this case, the governing equations of the problem become more complicated for a closed form solution. An interesting and practical extension of the problem is the vibration analysis of layered shells

  19. On what controls the spacing of spontaneous adiabatic shear bands in collapsing thick-walled cylinders

    Directory of Open Access Journals (Sweden)

    Lovinger Zev

    2015-01-01

    Full Text Available Shear bands formation in collapsing thick walled cylinders occurs in a spontaneous manner. The advantage of examining spontaneous, as opposed to forced shear localization, is that it highlights the inherent susceptibility of the material to adiabatic shear banding without prescribed geometrical constraints. The Thick-Walled Cylinder technique (TWC provides a controllable and repeatable technique to create and study multiple adiabatic shear bands. The technique, reported in the literature uses an explosive cylinder to create the driving force, collapsing the cylindrical sample. Recently, we developed an electro-magnetic set-up using a pulsed current generator to provide the collapsing force, replacing the use of explosives. Using this platform we examined the shear band evolution at different stages of formation in 7 metallic alloys, spanning a wide range of strength and failure properties. We examined the number of shear bands and spacing between them for the different materials to try and figure out what controls these parameters. The examination of the different materials enabled us to better comprehend the mechanisms which control the spatial distribution of multiple shear bands in this geometry. The results of these tests are discussed and compared to explosively driven collapsing TWC results in the literature and to existing analytical models for spontaneous adiabatic shear localization.

  20. Free surface heat transfer and innovative designs for thin and thick liquid walls

    International Nuclear Information System (INIS)

    Design windows on free surface flows in the APEX (advanced power extraction) study are derived from the viewpoints of the free surface heat transfer, the adaptation of liquid flows to the topological constraints, and temperature requirements for plasma operation and power conversion efficiency. Within these constraints, the temperature of the free liquid surface facing the plasma is the most critical parameter governing the amount of liquid that evaporates into the plasma chamber. Present analyses show that a 2 cm or a 40 cm thick lithium layer can be established throughout the ARIES-RS reactor using a velocity of 10 m s-1 while operating under the plasma compatible surface temperature. However, like solid metallic walls, the liquid lithium walls require the use of electrical insulators to overcome the MHD drag. As for Flibe free surface flows, the MHD effect caused by interaction with the mean flow is negligible, while a fairly uniform flow of 2 or 45 cm thick can be maintained throughout the reactor based on 3-D hydrodynamics calculations. However, being a low thermally conducting medium, the Flibe surface temperature highly depends on the extent of the turbulent convection. The heat transfer analyses based on the κ-ε model of the turbulence, including MHD effects and various boundary conditions, predict a range of temperatures that may be beyond the plasma compatible temperatures. If indeed the Flibe surface temperature is high relative to the plasma operation limit, further design adjustments will be required to accommodate this deficiency

  1. Electromagnetic acoustic transducers for wall thickness applications in the petrochemical industry

    Science.gov (United States)

    Edwards, C.; Dixon, S.; Widdowson, A.; Palmer, S. B.

    2000-05-01

    Electromagnetic acoustic transducers (EMATs) are now becoming widely used in the field, for example for boiler tube wall thickness surveys in Power Generation plant. In general EMATs work efficiently on steel components with a surface oxide layer, where the oxides can be residual mill scale from the steel manufacturing process due to in-service growth in boilers or chemical processing plant. Very often these oxides have rough surfaces and have to be removed prior to conventional ultrasonic inspection. This can be both time consuming and costly, in addition the removal of the protective oxide layer accelerates the future wall lose rate of the pipe or vessel. As well as the Power Generation application, EMATs can also be used for ultrasonic inspection of petrochemical tubulars without having to remove oxides giving the same associated benefits. This paper presents results obtained from laboratory trials of EMAT thickness monitoring of petrochemical plant pipe samples and real EMAT surveys carried out on-site on refinery plant. In parallel with the practical application of EMATs we are studying the underlying physics of operation with the aim of predicting the EMAT performance for steels with and without oxide layers.

  2. Optimization of Cone Wall Thickness to Reduce High Energy Electron Generation for Fast-Ignition Scheme

    Science.gov (United States)

    Kojima, Sadaoki; Zhe, Zhang; Sawada, Hiroshi; Firex Team

    2015-11-01

    In Fast Ignition Inertial Confinement Fusion, optimization of relativistic electron beam (REB) accelerated by a high-intensity laser pulse is critical for the efficient core heating. The high-energy tail of the electron spectrum is generated by the laser interaction with a long-scale-length plasma and does not efficiently couple to a fuel core. In the cone-in-shell scheme, long-scale-length plasmas can be produced inside the cone by the pedestal of a high-intensity laser, radiation heating of the inner cone wall and shock wave from an implosion core. We have investigated a relation between the presence of pre-plasma inside the cone and the REB energy distribution using the Gekko XII and 2kJ-PW LFEX laser at the Institute of Laser Engineering. The condition of an inner cone wall was monitored using VISAR and SOP systems on a cone-in-shell implosion. The generation of the REB was measured with an electron energy analyzer and a hard x-ray spectrometer on a separate shot by injecting the LFEX laser in an imploded target. The result shows the strong correlation between the preheat and high-energy tail generation. Optimization of cone-wall thickness for the fast-ignition will be discussed. This work is supported by NIFS, MEXT/JSPS KAKENHI Grant and JSPS Fellows (Grant Number 14J06592).

  3. The influence of wall thickness on the microstructure of HPDC AE44 alloy

    Directory of Open Access Journals (Sweden)

    A. Kiełbus

    2007-08-01

    Full Text Available Purpose: The main objective of this study was determination of influence of wall thickness on the microstructure of die-cast magnesium alloy containing aluminum and rare earth elements.Design/methodology/approach: The study was conducted on die-cast magnesium alloy containing 4% wt. aluminum and 4 % wt. mixture of rare earth elements (mischmetal in the die-cast condition. The mischmetal includes cerium, lanthanum, neodymium and praseodymium. The microstructure was characterized by optical microscopy (Olympus GX-70 and a scanning electron microscopy (Hitachi S3400 equipped with an X-radiation detector EDS (VOYAGER of NORAN INSTRUMENTS. The phase identification of these alloys was identified by X-ray diffraction (JDX-75. Quantitative examination was conducted using the “MET-ILO” automatic image analysis programme.Findings: The decreasing of wall thickness of die-cast AE44 leads to grain size decrease and emergence new intermetallic phases in microstructure of this alloy. With increasing thickness higher porosity was observed in alloy.Research limitations/implications: Future researches should contain investigations of the influence of die-cast parameters on microstructure and porosity.Practical implications: AE44 magnesium alloy is used in automotive industry. Moreover, this alloy has a new potential application and results of investigations may be useful for preparing optimal technology of die casting and designing parts of car engine.Originality/value: The results of the researches make up a basis for the next investigations of magnesium alloys with addition of aluminum and rare earth elements designed to exploitation at temperature to 200°C.

  4. Pre-clinical atherosclerosis evaluated by carotid artery intima-media thickness and the risk factors in children

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-zheng; LIU Ying; MI Jie; TANG Chao-shu; DU Jun-bao

    2007-01-01

    Background Atherosclerosis as a cardiovascular disease was found to begin even in the fetal period. However,information about risk factors of pre-clinical atherosclerosis in childhood has been limited. Hence, this study was aimed to find out the risk factors of atherosclerosis by measuring the carotid artery intima-media thickness in children. High resolution B-mode ultrasound used to examine the carotid artery intima-media thickness was demonstrated to be useful in finding the early carotid structural changes.Methods The study included 79 children who were divided into two groups according to their ages: group Ⅰ consisted of 42 children with ages from 5 to 9 years and group Ⅱ consisted of 37 children with ages from 10 to 18 years, Among them,23 had a positive family history for risk, such as hypertension, obesity or dyslipidemia. Blood samples were collected and total cholesterol, triglycerides, high density lipoprotein and low density lipoprotein were assayed. The carotid artery intima-media thickness was measured by ultrasound. Comparisons were done between the two groups using Student's t tests and Chi-square analysis. Body mass index, blood pressure, levels of lipids, family history and the carotid artery intima-media thickness were calculated by conditional logistic regression analysis.Results Compared with the children without a positive family history, the incidence of the increased carotid artery intima-media thickness was significantly high (x2=4.364, P<0.05). There were no statistically significant differences between left and right carotid arteries in carotid artery intima-media thickness (P>0.05). In this study, diastolic blood pressure and the atherosclerosis index were suggested to be the risk factors to the thickened carotid artery intima-media thickness. In group I the diastolic blood pressure's odds radio was 1.187 (P=0.035) and the atherosclerosis index odds radio was 37.165 (P=0.001); in group Ⅱ the diastolic blood pressure's odds

  5. The relationship between distribution of body fat mass and carotid artery intima-media thickness in Korean older adults

    OpenAIRE

    Park, Jin-Kee; Park, Hyuntae; Kim, Kwi-Baek

    2015-01-01

    [Purpose] The aim of this study was to examine the relationships between the amount and distribution of body fat and the carotid intima-media thickness to explore whether coronary artery disease risk may be mediated through effects on the amount of fat mass in older adults. [Subjects and Methods] A total of 200 elderly females was participated. The percentage of body fat mass was measured by the bioelectrical impedance analysis method, and the carotid intima-media thickness was measured by B-...

  6. Method of non-contacting gauging of the wall thickness of tubes by backscattering of ionizing radiation

    International Nuclear Information System (INIS)

    A method is described which allows non-contacting rapid and precise estimation of the wall thickness, of steel tubes, as well as the maximum and the minimum thickness, with the aid of backscattering of 137Cs gamma rays. The construction of the measuring head is presented. By fitting the measured backscattering values to defined curves a mathematical expression for the influences of the opposite tube wall and the tube diameter was found. By making two measurements on exactly opposed places every pair of values can be assigned unmistakably to the corresponding wall thickness if the diameter is known. By gauging at four positions, each staggered at 900, the maximum and minimum thickness can be calculated. The obtainable accuracy is given by an estimation of errors. (orig.)

  7. Magnetic field effects for copper suspended nanofluid venture through a composite stenosed arteries with permeable wall

    Energy Technology Data Exchange (ETDEWEB)

    Akbar, Noreen Sher; Butt, Adil Wahid, E-mail: adil.maths86@gmail.com

    2015-05-01

    In the present paper magnetic field effects for copper nanoparticles for blood flow through composite stenosis in arteries with permeable wall are discussed. The copper nanoparticles for the blood flow with water as base fluid is not explored yet. The equations for the Cu–water nanofluid are developed first time in the literature and simplified using long wavelength and low Reynolds number assumptions. Exact solutions have been evaluated for velocity, pressure gradient, the solid volume fraction of the nanoparticles and temperature profile. The effect of various flow parameters on the flow and heat transfer characteristics is utilized. - Highlights: • It is observed that the velocity profile is symmetric for all the parameters and when we increase slip parameter α then there will be more resistance between blood and arteries, hence the blood flow slows down and velocity profile decreases. • It is seen that the velocity field rises due to high electromagnetic forces and buoyancy forces as compared to viscous forces. • It is also noticed that velocity is high for all the parameters in case of pure water as compare to Cu-water because copper makes arteries more flexible that makes the blood flow speed slow. • When we rise heat absorption parameter β then definitely temperature increases rapidly. • The wall shear stress increases for different values of the slip parameter α and the Darcy number D{sub α} with rapid change in copper as compared to pure water.

  8. Chlamydia pneumoniae and atherosclerosis. Identification of bacterial DNA in the arterial wall

    Directory of Open Access Journals (Sweden)

    Coutinho Mário Sérgio Soares de Azeredo

    2000-01-01

    Full Text Available OBJECTIVE: The intracellular Gram-negative bacterium Chlamydia pneumoniae has been associated with atherosclerosis. The presence of Chlamydia pneumoniae has been investigated in fragments of the arterial wall with a technique for DNA identification. METHODS: Arterial fragments obtained from vascular surgical procedures in 58 patients were analyzed. From these patients, 39 were males and the mean age was 65±6 years. The polymerase chain reaction was used to identify the bacterial DNA with a pair of primers that codify the major outer membrane protein (MOMP of Chlamydia pneumoniae. The amplified product was visualized by electrophoresis in the 2% agarose gel stained with ethidium bromide, and it was considered positive when migrating in the band of molecular weight of the positive controls. RESULTS: Seven (12% out of the 58 patients showed positive results for Chlamydia pneumoniae. CONCLUSION: DNA from Chlamydia pneumoniae was identified in the arterial wall of a substantial number of patients with atherosclerosis. This association, which has already been described in other countries, corroborates the evidence favoring a role played by Chlamydia pneumoniae in atherogenesis.

  9. Influence of tissue preservation methods on arterial geometry and echogenicity

    DEFF Research Database (Denmark)

    Sillesen, H.; Wilhjelm, J; Vogt, Katja;

    1997-01-01

    original, ultrasound, ultrasonic measurement, vessel diameter, wall thickness, measurement of echogenicity, freezing of specimen, formalin fixation, pressurized formalin fixation, porcine artery......original, ultrasound, ultrasonic measurement, vessel diameter, wall thickness, measurement of echogenicity, freezing of specimen, formalin fixation, pressurized formalin fixation, porcine artery...

  10. Prevalence and Risk Factors of Carotid Vessel Wall Inflammation in Coronary Artery Disease Patients

    Science.gov (United States)

    Bucerius, Jan; Duivenvoorden, Raphaël; Mani, Venkatesh; Moncrieff, Colin; Rudd, James H. F.; Calcagno, Claudia; Machac, Josef; Fuster, Valentin; Farkouh, Michael E.; Fayad, Zahi A.

    2014-01-01

    OBJECTIVES We investigated the prevalence and clinical risk factors of carotid vessel wall inflammation by means of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in a population consisting of coronary artery disease (CAD) patients. BACKGROUND The atherosclerotic disease process is characterized by infiltration and retention of oxidized lipids in the artery wall, triggering a disproportionate inflammatory response. Efforts have been made to use noninvasive imaging to quantify this inflammatory response in the vessel wall. Recently, carotid FDG-PET has been shown to reflect the metabolic rate of glucose, a process known to be enhanced in inflamed tissue. METHODS Carotid inflammation was quantified in 82 CAD patients (age 62 ± 10 years) as the maximum target-to-background ratio (wholevesselTBRmax). Furthermore, we assessed the maximal standardized uptake value values (wholevesselSUVmax), the single hottest segment (SHS), and the percent active segments (PAS) of the FDG uptake in the artery wall, measured by FDG-PET. RESULTS Whole-vessel TBRmax > 1.8 was present in 67%, > 2.0 in 39%, > 2.2 in 23%, and > 2.4 in 12% of the population. Multiple linear regression analysis with backward elimination revealed that body mass index (BMI) ≥ 30 kg/m2 (p 65 years (p = 0.01), smoking (p = 0.02), and hypertension (p = 0.01) were associated with wholevesselTBRmax. The number of components of the metabolic syndrome was also associated with wholevesselTBRmax (p = 0.02). In similar analyses, wholevesselSUVmax was associated with BMI ≥30 kg/m2 (p 65 years (p = 0.004), male gender (p = 0.02), and hypertension (p = 0.04); SHS with BMI ≥30 kg/m2 (p 65 years (p = 0.02), smoking (p = 0.04), and hypertension (p = 0.05); PAS with BMI ≥30 kg/m2 (p = 0.001), smoking (p = 0.03), and hypertension (p = 0.01). CONCLUSIONS Carotid inflammation as revealed by FDG-PET is highly prevalent in the CAD population and is associated with obesity, age over 65 years, history of

  11. Process for measuring the wall thickness of bodies by means of ultrasonic pulses and device for carrying out the process

    International Nuclear Information System (INIS)

    The ultrasonic pulses are produced in the bodies and reflected at the walls. The running times of the pulses reflected at the walls are measured. The wall thickness is determined from the running times via the speed of sound in the body. The signals obtained with a receiver are compared with a threshold value, which is set at the start of the measurement to a low basic value. For each signal measured which exceeds the appropriate threshold values are measured. The maximum value of time corresponds to the running time of the rear wall echo. (orig./HP)

  12. Quantitative computed tomography: emphysema and airway wall thickness by sex, age and smoking

    DEFF Research Database (Denmark)

    Grydeland, T B; Dirksen, A; Coxson, H O;

    2009-01-01

    We investigated how quantitative high-resolution computed tomography (HRCT) measures of emphysema and airway wall thickness (AWT) vary with sex, age and smoking history. We included 463 chronic obstructive pulmonary disease (COPD) cases and 431 controls. All included subjects were current or ex...... cases, respectively, and 0.71 (0.3-1.6) and 0.32 (0.1-0.8) in male and female controls, respectively. %LAA950 was higher in ex-smokers and increased with increasing age and with increasing number of pack-years. The mean+/-SD standardised AWT was 0.504+/-0.030 and 0.474+/-0.031 in male and female COPD...... varying sex, age and smoking groups of both control and COPD subjects....

  13. A semi-analytic analysis of shape memory alloy thick-walled cylinders under internal pressure

    Energy Technology Data Exchange (ETDEWEB)

    Mirzaeifar, Reza [Georgia Institute of Technology, George W. Woodruff School of Mechanical Engineering, Atlanta, GA (United States); Shakeri, Mahmoud [Amirkabir University of Technology, Mechanical Engineering Department, Tehran (Iran, Islamic Republic of); DesRoches, Reginald; Yavari, Arash [Georgia Institute of Technology, School of Civil and Environmental Engineering, Atlanta, GA (United States)

    2011-08-15

    In this paper, a new method for analysis of the pseudoelastic response of shape memory alloy thick-walled cylinders subjected to internal pressure is proposed. Two cases of short and long cylinders are considered by assuming the plane stress and plane strain conditions. In each case, a three-dimensional phenomenological SMA constitutive model is simplified to obtain the corresponding two-dimensional constitutive relations. The cylinder is partitioned into a finite number of narrow annular regions, and appropriate assumptions are made in order to find a closed-form solution for the equilibrium equations in each annular region. The global solution is obtained by enforcing the stress continuity condition at the interface of the annular regions and imposing the boundary conditions. Several numerical examples are presented to demonstrate the efficiency of the proposed method, and the results are compared with three-dimensional finite element simulations. (orig.)

  14. Biometric estimation of chest wall thickness in female nonradiation workers of a monazite processing plant

    International Nuclear Information System (INIS)

    Chest wall thickness (CWT) was estimated in fifty four female nonradiation workers of a monazite processing plant by biometric measurements. The CWT ranged from 4.12 cm to 6.94 cm giving an average of 5.19 ± 0.76 cm. CWT was found to have very good correlation with percent Body Fat and abdominal circumference but poor correlation with Body Mass Index, Body Build Index, Slenderness, age etc. CWT increases with age especially in the upper middle-aged group (> 35 years). A single measurement of abdominal circumference can be used to estimate CWT with 94 % accuracy. A factor of 0.0587 was derived to estimate CWT from abdominal circumference. The study also showed that about 11 % of the subjects were obese. The results obtained will be very useful for the accurate measurement of Low Energy Photons like 239Pu and 241Am deposited in the lung. (author)

  15. Fatigue and creep cracking of thick-walled tubes under bending stress

    International Nuclear Information System (INIS)

    In the scope of safety certification of an HTR plant for power generation, fracture mechanical tests were conducted on the creep and fatigue crack growth behaviours of the material X10 NiCrAlTi32 20 (Alloy 800). This involved the use of pipes of the dimensions 197 mm O.D. and 23.5 mm wall thickness. They were provided with a 180deg circumferential defect each and subjected to static or cyclic loads under 4-point-bending. For the specimen geometry used here several approximative solutions known from literature were investigated in respect of their applicability. This involved a finite element calculation which considered the true defect geometry and load condition. The line spring model delivered in the KI-values the best correlation with the FE-calculation and therefore was used for recalculating the component tests conducted. (orig./DG)

  16. Calculation of the thicknesses of the walls of the radiographic inspection building of the NKS enterprise

    International Nuclear Information System (INIS)

    During the month of February, 1983, the Structural Civil Department of the Latin American of Engineering, S.A. de C.V. company (LATISA), outline to the Engineering and Industry Applications Management of the ININ that the industrial group NKS had taken charge them the design of a building where it would lodge a linear electron accelerator of 4 MeV, one source of Co-60 of 30 Ci and an X-ray equipment, tube type, of range of 60 to 300 KV and that to make the design they required to know the necessary thickness of the walls, doors and roof to protect to the workers, outside of the building, of the X and gamma radiations generated by the sources mentioned during the radiographic inspections of metal-mechanical pieces. (Author)

  17. Contrast-enhanced magnetic resonance angiography of carotid arterial wall in pigs.

    Science.gov (United States)

    Lin, W; Abendschein, D R; Haacke, E M

    1997-01-01

    This study was designed to investigate the effects of contrast agents on MR images of balloon-injured carotid arteries containing atherosclerotic-like lesions. We have evaluated an intravascular contrast agent, MS-325 (METASYN INC., Cambridge, MA) and an extravascular contrast agent, Optimark, (Mallinckrodt Medical Inc., St. Louis, MO) on MR angiograms obtained 4 weeks after balloon hyperinflation-induced injury of the left common carotid artery in 12 hypercholesterolemic minipigs. High in-plane resolution (.8 x .4 mm2), thin slice (1 mm) time-of-flight gradient echo sequences were used to acquire the MR angiographic images. Vascular lumen definition was compared before and after a single bolus intravenous injection of a contrast agent. Digital subtraction angiograms were obtained from all pigs after MR imaging. High grade stenosis developed in 1 of the 12 pigs and five pigs had complete occlusion of the injured vessel. The remaining pigs exhibited essentially no visible stenoses as assessed either by MR angiography or digital subtraction angiography. The vessel walls of the stenosed and occluded vessels were visible after the injection of either intravascular or extravascular contrast agent. Histologic analyses showed well developed neovascularization in the neointima or occlusive thrombosis. We conclude that the observed contrast-enhanced vessel wall is caused by an increased vascular supply associated with thrombosis and neointimal thickening that leads to an accumulation of contrast agent in the abnormal vessel walls after the injection of the T1-shortening paramagnetic contrast agent. PMID:9039613

  18. Development of eddy current testing probe for thick-walled metal plate and quantitative evaluation of cracks

    International Nuclear Information System (INIS)

    This paper demonstrates the crack detection of thick-walled non-magnetic metal plates by eddy current testing, which is difficult because of Kelvin skin effect generally. The purpose of this research is the development of an new eddy current testing probe for cracks in thick-walled plates and crack shapes quantitative evaluation. The probe was designed, based on the numerical computation using 3D fast eddy current code. The advantages of this new probe are strong eddy current on the back of specimens and gentle decrement of eddy current in the thickness direction. Through experiments, we confirmed that this probe can detect the back artificial defect with 0.5 mm thickness on IN-CONEL 718 specimen with 7.0 mm thickness. Reconstruction of crack shapes was performed based on the experimental results with the inverse problem code developed by authors. The length and depth of reconstructed defects approximately agree with those of real crack. (author)

  19. Development of eddy current testing probe for thick-walled metal plate and quantitative evaluation of cracks

    CERN Document Server

    Sato, K; Uchimoto, T; Takagi, T

    2003-01-01

    This paper demonstrates the crack detection of thick-walled non-magnetic metal plates by eddy current testing, which is difficult because of Kelvin skin effect generally. The purpose of this research is the development of an new eddy current testing probe for cracks in thick-walled plates and crack shapes quantitative evaluation. The probe was designed, based on the numerical computation using 3D fast eddy current code. The advantages of this new probe are strong eddy current on the back of specimens and gentle decrement of eddy current in the thickness direction. Through experiments, we confirmed that this probe can detect the back artificial defect with 0.5 mm thickness on IN-CONEL 718 specimen with 7.0 mm thickness. Reconstruction of crack shapes was performed based on the experimental results with the inverse problem code developed by authors. The length and depth of reconstructed defects approximately agree with those of real crack. (author)

  20. Ultrasonic wall thickness gauging for ferritic steam generator tubing as an in-service inspection tool

    International Nuclear Information System (INIS)

    In-service inspection of LWR steam generators is more or less a standard routine operation. The situation can be very different for LMFBRs. For the SNR 300 (Kalkar Power Station) the situation is different because the steam generators have ferritic tubing. The tube walls are comparatively thick, 2 to 4.5 mm. During inservice examinations the steam generators will be drained on both sides, however on the sodium side a sodium film will be present. Furthermore the SNR 300 will have two types of steam generator. A straight tube design and a helical coil design will be used. Both types consist of a evaporator and superheater. The steam generators are of course not radioactive. It is obvious that in this case the eddy current (EC) technique is not an enviable inservice inspection tool. Basically EC is a surface flaw detection technique. Only the saturation magnetisation method will improve the EC technique sufficiently for ferritic material. However the 'in bore examination' with the saturation technique was, in case of the SNR 300 steam generator tubing, considered impossible since the inner diameters are fairly small. Furthermore sodium traces may influence the EC method. Although multifrequency methods can solve this problem, EC is not considered as a useful tool for examining ferritic tubing. Another method is to employ the 'stray flux' method which is under development with the TNO organization in Holland. The EC and stray flux method do have one drawback, these methods do not detect gradual changes in wall thickness. Ultrasonic examinations will be used in the SNR 300 as the main inspection tool for the steam generators. In this paper the reasons why ultrasonic examination was selected are explained. The results of the development work on this subject are discussed

  1. Effect of hypertension on low-density lipoprotein transport within a multi-layered arterial wall: modelling consistent with experiments

    CERN Document Server

    Jesionek, Katarzyna; Kostur, Marcin

    2016-01-01

    The influence of hypertension on low-density lipoproteins intake into the arterial wall is an important factor for understanding mechanisms of atherosclerosis. It has been experimentally observed that the increased pressure leads to the higher level of the LDL inside the wall. In this paper we attempt to construct a model of the LDL transport which reproduces quantitatively experimental outcomes. We supplement the well known four-layer arterial wall model to include two pressure induced effects: the compression of the intima tissue and the increase of the fraction of leaky junctions. We demonstrate that such model can reach the very good agreement with experimental data.

  2. Manufacturing and maintenance technologies developed for a thick-wall structure of the ITER vacuum vessel

    International Nuclear Information System (INIS)

    Development of welding, cutting and non-destructive testing (NDT) techniques, and development of remotized systems have been carried out for on-site manufacturing and maintenance of the thick-wall structure of the International Thermonuclear Experimental Reactor (ITER) vacuum vessel (VV). Conventional techniques, including tungsten inert gas welding, plasma cutting, and ultrasonic inspection, have been improved and optimized for the application to thick austenitic stainless steel plates. In addition, advanced methods have been investigated, including reduced-pressure electron-beam and multi-pass neodymium-doped yttrium aluminum garnet (NdYAG) laser welding, NdYAG laser cutting, and electro-magnetic acoustic transducer inspection, to improve cost and technical performance. Two types of remotized systems with different payloads have been investigated and one of them has been fabricated and demonstrated in field joint welding, cutting, and NDT tests on test mockups and full-scale ITER VV sector models. The progress and results of this development to date provide a high level of confidence that the manufacturing and maintenance of the ITER VV is feasible

  3. Residual stress simulation in thin and thick-walled stainless steel pipe welds including pipe diameter effects

    International Nuclear Information System (INIS)

    In this paper, residual stresses in welded components are discussed and a brief review of weld simulation is presented. The general methodology of the FE analysis methods used for welded sections of steel pipes is explained. FE analyses are performed for two axisymmetric butt welds in stainless steel pipes having a 4-pass or a 36-pass weld in a pipe with a wall thickness of 7.1 or 40.0 mm, respectively. In addition, more FE models with inside radius to wall thickness ratio ranging from 1 to 100 have been analysed to investigate the effect of pipe diameter on residual stresses. Residual axial and hoop stresses are plotted for the considered range of pipe diameters for the two simulated pipe wall thicknesses and the differences are discussed

  4. NUMERICAL SIMULATION OF EFFECTS OF WALL THICKNESS AND CELL DENSITY ON THE THREE-WAY CATALYTIC CONVERTER PERFORMANCE

    Institute of Scientific and Technical Information of China (English)

    Wu Guojiang; Tan Song; Huang Zhen

    2005-01-01

    The transient symmetric mathematical model is established, and the effects of the wall thickness and cell density on the performance of a three-way catalytic converter are studied using numerical modeling. The conclusions show that the light-off time and the pressure drop through a converter are decreased, and the conversion efficiency during the warm-up period keeps almost invariant with reduction of the wall thickness of substrates, and that the pressure drop through a converter and a conversion efficiency during the warm-up state increases, and the light-off time almost keeps invariant when increasing cell density of substrates. Therefore, future catalytic converters should develop in the direction of thin wall thickness and high cell density substrates simultaneously.

  5. Automated image segmentation and registration of vessel wall MRI for quantitative assessment of carotid artery vessel wall dimensions and plaque composition

    OpenAIRE

    Klooster, Ronald van 't

    2014-01-01

    The main goal of this thesis was to develop methods for automated segmentation, registration and classification of the carotid artery vessel wall and plaque components using multi-sequence MR vessel wall images to assess atherosclerosis. First, a general introduction into atherosclerosis and different stages of the disease were described including the importance to differentiate between stable and vulnerable plaques. Several non-invasive imaging techniques were discussed and the advantages of...

  6. Joint segmentation of lumen and outer wall from femoral artery MR images: Towards 3D imaging measurements of peripheral arterial disease.

    Science.gov (United States)

    Ukwatta, Eranga; Yuan, Jing; Qiu, Wu; Rajchl, Martin; Chiu, Bernard; Fenster, Aaron

    2015-12-01

    Three-dimensional (3D) measurements of peripheral arterial disease (PAD) plaque burden extracted from fast black-blood magnetic resonance (MR) images have shown to be more predictive of clinical outcomes than PAD stenosis measurements. To this end, accurate segmentation of the femoral artery lumen and outer wall is required for generating volumetric measurements of PAD plaque burden. Here, we propose a semi-automated algorithm to jointly segment the femoral artery lumen and outer wall surfaces from 3D black-blood MR images, which are reoriented and reconstructed along the medial axis of the femoral artery to obtain improved spatial coherence between slices of the long, thin femoral artery and to reduce computation time. The developed segmentation algorithm enforces two priors in a global optimization manner: the spatial consistency between the adjacent 2D slices and the anatomical region order between the femoral artery lumen and outer wall surfaces. The formulated combinatorial optimization problem for segmentation is solved globally and exactly by means of convex relaxation using a coupled continuous max-flow (CCMF) model, which is a dual formulation to the convex relaxed optimization problem. In addition, the CCMF model directly derives an efficient duality-based algorithm based on the modern multiplier augmented optimization scheme, which has been implemented on a GPU for fast computation. The computed segmentations from the developed algorithm were compared to manual delineations from experts using 20 black-blood MR images. The developed algorithm yielded both high accuracy (Dice similarity coefficients ≥ 87% for both the lumen and outer wall surfaces) and high reproducibility (intra-class correlation coefficient of 0.95 for generating vessel wall area), while outperforming the state-of-the-art method in terms of computational time by a factor of ≈ 20. PMID:26387053

  7. Impairment of left ventricular regional wall motion in diabetes mellitus without coronary artery disease

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Ken`ya; Shimonagata, Tuyoshi; Nanto, Shinsuke; Kuroda, Akio; Morozumi, Takakazu; Kamado, Kenji; Nagata, Seiki [Kansai Rosai Hospital, Amagasaki, Hyogo (Japan); Yamasaki, Yoshimitsu

    1996-09-01

    To elucidate the mechanisms of diabetic cardiomyopathy, dual SPECT imaging with thallium-201 (Tl-201) and I-123 beta-methyl-p-iodophenyl pentadecanoic acid (BMIPP), a branched analogue of free fatty acid (FFA), and dipyridamole-infusion Tl-201 scintigraphy were performed in 28 NIDDM patients without coronary artery disease. Twenty eight patients were divided into two groups based on the presence of wall motion abnormalities on cineangiographic left ventriculography (LVG). Nineteen patients with normal wall motion documented on LVG (group A) out of 28 evaluated patients demonstrated normal Tl-201 and I-123 BMIPP uptake in dual SPECT imaging, whereas 9 patients with reduced wall motion (group B) demonstrated reduced I-123 BMIPP uptake when compared with Tl-201 uptake. On dipyridamole-infusion Tl-201 scintigraphy, transient perfusion defects were demonstrated in 4 patients of group B and two patients of group A (p<0.05). These results suggest that small vessel disease and the impairment of myocardial free fatty acid metabolism are etiologic or contributory factors for regional wall motion abnormality in diabetic cardiomyopathy. (author)

  8. Theoretical analysis of metallic nanoparticles on blood flow through stenosed artery with permeable walls

    International Nuclear Information System (INIS)

    The present analysis deals with the study of physical characteristics of blood flow in the presence of stenosis and nanoparticles through a curved channel with permeable walls. Taking mild stenosis case, the governing equations for anticipated model are solved using the corresponding boundary conditions and close-form solutions have been obtained for temperature, velocity and slip velocity by using Cauchy Euler's method. The expressions for the resistance impedance and pressure gradient in the stenotic region have also been obtained and the existence of various pertinent flow parameters, mainly Darcy number, slip parameter and nanoparticles volume fraction, has been discussed through graphs. - Highlights: • Nanoparticles analysis is discussed for diverging converging and non-tapered arteries. • Resistance impedance decreases with an increase in the nanoparticles volume fraction. • Combination of curvature and stenosis shows stenosis dominant the curvature of artery. • Pressure possesses an inverse variation to the resistance with respect to tapering. • Trapping shows that the symmetry destroys due to increase in curvature of curved artery

  9. Carotid Artery Wall Segmentation in Multispectral MRI by Coupled Optimal Surface Graph Cuts.

    Science.gov (United States)

    Arias-Lorza, Andres M; Petersen, Jens; van Engelen, Arna; Selwaness, Mariana; van der Lugt, Aad; Niessen, Wiro J; de Bruijne, Marleen

    2016-03-01

    We present a new three-dimensional coupled optimal surface graph-cut algorithm to segment the wall of the carotid artery bifurcation from Magnetic Resonance (MR) images. The method combines the search for both inner and outer borders into a single graph cut and uses cost functions that integrate information from multiple sequences. Our approach requires manual localization of only three seed points indicating the start and end points of the segmentation in the internal, external, and common carotid artery. We performed a quantitative validation using images of 57 carotid arteries. Dice overlap of 0.86 ± 0.06 for the complete vessel and 0.89 ± 0.05 for the lumen compared to manual annotation were obtained. Reproducibility tests were performed in 60 scans acquired with an interval of 15 ± 9 days, showing good agreement between baseline and follow-up segmentations with intraclass correlations of 0.96 and 0.74 for the lumen and complete vessel volumes respectively. PMID:26595912

  10. Theoretical analysis of metallic nanoparticles on blood flow through stenosed artery with permeable walls

    Energy Technology Data Exchange (ETDEWEB)

    Nadeem, S.; Ijaz, S., E-mail: shaguftaijaz11@yahoo.com

    2015-03-06

    The present analysis deals with the study of physical characteristics of blood flow in the presence of stenosis and nanoparticles through a curved channel with permeable walls. Taking mild stenosis case, the governing equations for anticipated model are solved using the corresponding boundary conditions and close-form solutions have been obtained for temperature, velocity and slip velocity by using Cauchy Euler's method. The expressions for the resistance impedance and pressure gradient in the stenotic region have also been obtained and the existence of various pertinent flow parameters, mainly Darcy number, slip parameter and nanoparticles volume fraction, has been discussed through graphs. - Highlights: • Nanoparticles analysis is discussed for diverging converging and non-tapered arteries. • Resistance impedance decreases with an increase in the nanoparticles volume fraction. • Combination of curvature and stenosis shows stenosis dominant the curvature of artery. • Pressure possesses an inverse variation to the resistance with respect to tapering. • Trapping shows that the symmetry destroys due to increase in curvature of curved artery.

  11. Comparison of common carotid artery intima-media thickness between Brazilian Euro-descendants and Afro-descendants with atherosclerosis risk factors

    Directory of Open Access Journals (Sweden)

    Ivan Benaduce Casella

    2009-01-01

    Full Text Available OBJECTIVE: To compare common carotid intima-media thickness (IMT between the two major Brazilian ethnic groups (those of African descent and those of European descent among individuals with one or more risk factors for atherosclerotic disease. METHOD: Two hundred and six patients with one or more risk factors for atherosclerotic disease were evaluated in a cross-sectional study in which their clinical, ethnic and Demographic characteristics were collected. All patients underwent duplex ultrasound examination of their carotid vessels to obtain IMT measurements. RESULTS: One hundred and fifty-three patients (74.3% had a carotid IMT greater than 1.0 mm at one or more point of measurement in at least one common carotid artery. There was a significant correlation between older age and mean carotid wall thickness (R=0.479 / P<0.01. Multivariate analysis identified male sex, arterial hypertension and older age as variables associated with increased IMT (P<0.05 for all variables. When IMT was compared between the two ethnic groups in this study, no significant differences were noted. Euro-descendants and Afro-descendants had similar IMT values, even when the groups were stratified by degree of IMT (normal vs. increased and presence of stroke and/or transient ischemic attack (yes vs. no. CONCLUSIONS: The risk factors associated with increased common carotid artery IMT in Brazilian individuals are similar to those in previously described populations. No differences were observed between the two main Brazilian ethnic groups. Longitudinal studies are required for a better evaluation of the incidence, etiologic factors and evolution of carotid intimomedial thickening in this population.

  12. Experiments on thick-walled, unarmoured concrete rings subjected to internal pressure loads

    International Nuclear Information System (INIS)

    This paper presents three tests on thick-walled concrete cylinders loaded by an interior pressure. The specimens were not reinforced. They had an inner diameter of 21.8 cm, an outer diameter of 73.0 and 125.0 cm and were 10 cm thick. Shrinkage effects were prevented as well as possible. The strains were measured by electric gages, which formed a triangular mesh on the upper face of the specimen. The increase of pressure was controlled by the condition of linear increase of the tangential strains at the inner perimeter of the ring. By this method it was possible to measure the strains even in the phase of failure. At the inner diameter strains about 0.5 per mill were measured without visible cracks. These strains were observed over a gage-length of 10 cm. Therefore, it can be assumed that at the cracking-point was an even higher strain. At the point where cracking occured, micro-cracking caused a decrease of strains and stresses in the neighbouring zones before the cracks were visible. The specimens failed after reaching the maximum load in a falling branch of the load. The failure occured suddenly by a primary crack and a secondary crack at the opposite side. The maximum inside pressure depended in a small range on the size of the cylinders. The results were analysed by available theories and compared with similar tests of Martin. The interpretation of the maximum load depends in a big range on the assumptions of the tensile strength of the concrete (axial tensile strength, bending tensile strength, tensile stresses after microcracking). Hereby exists a wide scale which complicates a definite statement. Further research must be done to examine the material law of concrete in the tensile range. Only by this way a definite solution for concrete cylinders with inside pressure is possible. (orig.)

  13. Factors associated with gender difference in the intima-media thickness of the common carotid artery

    International Nuclear Information System (INIS)

    Aim: To investigate the gender differences associated with a thinner intima-media thickness (IMT) of the common carotid artery (CCA) in women. Materials and methods: In a sample of 218 consecutive healthy volunteers comprising 110 men and 108 women, the IMT of the CCA was measured using B-mode ultrasonography. Blood pressure, fasting blood sugar, body mass index (BMI), blood lipid profile, homocysteine, folic acid, uric acid, high sensitive C-reactive protein, and thiobarbituric acid reactive substances (TBARS) levels were measured and compared with each other in both genders. Results: The IMT of the CCA was significantly thinner in women than in men (p = 0.012). Blood pressure, fasting plasma glucose, BMI, low-density lipoprotein cholesterol, triglycerides, homocysteine, uric acid, and TBARS were significantly (p < 0.05) lower, folic acid and high-density lipoprotein cholesterol (HDL-C) were significantly (p < 0.0001) higher in women compared with men. Multivariable logistic regression analysis revealed that higher serum levels of homocysteine, uric acid, and TBARS, and lower serum levels of HDL-C were significantly (p < 0.05) associated with male sex. Multiple linear regression analysis further revealed that age, sex, and BMI were independently associated with CCA IMT. Conclusions: The IMT of the CCA was thinner in women than in men. Traditional vascular risk factors explain only a small amount of variance in multivariate regression models supporting the hypothesis that other behavioural, sex hormone-related or genetic factors, which have not been sufficiently explored so far, may play a role in the gender differences of IMT.

  14. Factors associated with gender difference in the intima-media thickness of the common carotid artery

    Energy Technology Data Exchange (ETDEWEB)

    Tan, T.-Y.; Lu, C.-H.; Lin, T.-K.; Liou, C.-W. [Department of Neurology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan (China); Chuang, Y.-C., E-mail: tengyeowtan@yahoo.co [Department of Neurology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan (China); Schminke, U. [Department of Neurology, Ernst Moritz Arndt University, Greifswald (Germany)

    2009-11-15

    Aim: To investigate the gender differences associated with a thinner intima-media thickness (IMT) of the common carotid artery (CCA) in women. Materials and methods: In a sample of 218 consecutive healthy volunteers comprising 110 men and 108 women, the IMT of the CCA was measured using B-mode ultrasonography. Blood pressure, fasting blood sugar, body mass index (BMI), blood lipid profile, homocysteine, folic acid, uric acid, high sensitive C-reactive protein, and thiobarbituric acid reactive substances (TBARS) levels were measured and compared with each other in both genders. Results: The IMT of the CCA was significantly thinner in women than in men (p = 0.012). Blood pressure, fasting plasma glucose, BMI, low-density lipoprotein cholesterol, triglycerides, homocysteine, uric acid, and TBARS were significantly (p < 0.05) lower, folic acid and high-density lipoprotein cholesterol (HDL-C) were significantly (p < 0.0001) higher in women compared with men. Multivariable logistic regression analysis revealed that higher serum levels of homocysteine, uric acid, and TBARS, and lower serum levels of HDL-C were significantly (p < 0.05) associated with male sex. Multiple linear regression analysis further revealed that age, sex, and BMI were independently associated with CCA IMT. Conclusions: The IMT of the CCA was thinner in women than in men. Traditional vascular risk factors explain only a small amount of variance in multivariate regression models supporting the hypothesis that other behavioural, sex hormone-related or genetic factors, which have not been sufficiently explored so far, may play a role in the gender differences of IMT.

  15. Comparison between Carotid Intima-Media Thickness and Coronary Artery Calcification in the Prediction of Atherosclerosis in Diabetic Patients

    Directory of Open Access Journals (Sweden)

    Rusli Muljadi

    2014-04-01

    Full Text Available BACKGROUND: Cardiovascular disease is one of the atherosclerosis etiologies that can lead to death. Diabetes mellitus increases the risk of atherosclerosis. Screening tool is very beneficial for detecting atherosclerotic plaque, especially in subclinical atherosclerotic cases. Carotid intima-media thickness (CIMT and coronary artery calcification score (CACS are two kinds of tools that are widely used, and each of these tools has its own superiority. This study was aimed to investigate the sensitivity and specificity of both of these tools as screening tools. METHODS: The study was conducted with a cross sectional design involving 43 diabetic and 68 non-diabetic male subjects aged above 45 years old. All subjects fulfilled inclusion criteria. Carotid artery ultrasonography and CACS measurement were performed. RESULTS: Fischer exact test was used to show a significant correlation between CIMT and CACS (p<0.05. Diagnostic test was used to assess the sensitivity of CIMT toward CACS in above 75 percentile. The left common carotid artery (LCCA showed the highest sensitivity either in diabetic (76.4% or non-diabetic male subjects (90%. CONCLUSIONS: CIMT has the same sensitivity with CACS. CIMT can be used as the preferred screening tool for high risk patients and as a substitution tool to CACS for low risk patients in subclinical atherosclerosis detection. KEYWORDS: atherosclerosis, diabetes mellitus, carotid intima-media thickness, coronary artery calciication score.

  16. Comparison between Carotid Intima-Media Thickness and Coronary Artery Calcification in the Prediction of Atherosclerosis in Diabetic Patients

    OpenAIRE

    Rusli Muljadi; Bachtiar Murtala; Peter Kabo; FX Budhianto Suhadi

    2014-01-01

    BACKGROUND: Cardiovascular disease is one of the atherosclerosis etiologies that can lead to death. Diabetes mellitus increases the risk of atherosclerosis. Screening tool is very beneficial for detecting atherosclerotic plaque, especially in subclinical atherosclerotic cases. Carotid intima-media thickness (CIMT) and coronary artery calcification score (CACS) are two kinds of tools that are widely used, and each of these tools has its own superiority. This study was aimed to investigate the ...

  17. Modeling Periodic Adiabatic Shear Bands Evolution in a 304L Stainless Steel Thick-Walled Cylinder

    Science.gov (United States)

    Liu, Mingtao; Hu, Haibo; Fan, Cheng; Tang, Tiegang

    2015-06-01

    The self-organization of multiple shear bands in a 304L stainless steel thick-walled cylinder (TWC) was numerically studied. The microstructures of material lead to the non-uniform distribution of local yield stress, which plays a key role in the formation of spontaneous shear localization. We introduced a probability factor satisfied Gauss distribution into the macroscopic constitutive relationship to describe the non-uniformity of local yield stress. Using the probability factor, the initiation and propagation of multiple shear bands in TWC were numerically replicated in our 2D FEM simulation. Experimental results in the literature indicate that the machined surface at the internal boundary of a 304L stainless steel cylinder provides a work-hardened layer (about 20 μm) which has significantly different microstructures from base material. The work-hardened layer leads to the phenomenon that most shear bands are in clockwise or counterclockwise direction. In our simulation, periodic oriented perturbations were applied to describe the grain orientation in the work-hardened layer, and the spiral pattern of shear bands was successfully replicated.

  18. Numerical simulation of the natural fragmentation of explosively loaded thick walled cylinders

    Institute of Scientific and Technical Information of China (English)

    I.G.CULLIS; P.DUNSMORE; A.HARRISON; I.LEWTAS; R.TOWNSLEY

    2014-01-01

    The ability to predict the natural fragmentation of an explosively loaded metal casing would represent a significant achievement. Physically-based material models permit the use of small scale laboratory tests to characterise and validate their parameters. The model can then be directly employed to understand and design the system of interest and identify the experiments required for validation of the predictions across a wide area of the performance space. This is fundamentally different to the use of phenomenologically based material algorithms which require a much wider range of characterisation and validation tests to be able to predict a reduced area of the performance space. Eulerians numerical simulation methods are used to describe the fragmentation of thick walled EN24 steel cylinders filled with PBXN-109 explosive. The methodology to characterise the constitutive response of the material using the physically based ArmstrongeZerilli constitutive model and the Goldthorpe path dependent fracture model is described, and the results are presented. The ability of an Eulerian hydrocode to describe the fragmentation process and reproduce the experimentally observed fragment mass and velocity distributions is presented and discussed. Finally the suitability of the current experimental analysis methodology for simulation validation is addressed.

  19. STATIONARY PROBLEM OF MOISTURE-INDUCED ELASTICITY OF HETEROGENEOUS THICK-WALLED CYLINDERS

    Directory of Open Access Journals (Sweden)

    Andreev Vladimir Igorevich

    2012-10-01

    Full Text Available Many problems of identification of the stress-strain state against the background of the heat and mass transfer are solved through the application of constant (averaged values of mechanical properties (elastic modulus, Poisson's ratio and derivation of differential equations with constant coefficients. Due to irregular distribution of temperature and other factors of impact, including the moisture content, mechanical properties of many materials change significantly; therefore, the problems in question are solved within the framework of mechanics of heterogeneous bodies. In this paper, the authors solve the classical problem of the steady-state moisture-induced elasticity of a thick-walled cylinder by taking account of the changes in the value of the elastic modulus caused by the influence of moisture. In this case, the problem is reduced to a differential equation with variable coefficients, which makes the solution more complicated though more accurate. It is proven that due regard for the heterogeneity leads to a significant increase in stresses, if compared to the solution based on the mean values of the modulus of elasticity.

  20. ELASTOPLASTIC ANALYSIS OF THICK-WALL CYLINDER CONSIDERING THE MATERIAL'S DILATANCY CHARACTER

    Institute of Scientific and Technical Information of China (English)

    江崎哲郎; 张铭; 竹下昭博; 三谷泰浩

    1995-01-01

    Impermeable bentonite or its mixtures have been proposed as candidate materials to be used in the geotechnical disposal of radioactive nuclear waste. These materials are filled in the space between a canister containing radioactive nuclear waste and an underground chamber to absorb the radionuclide emitting from the canister and simultaneously retard its migration accompanying the permeation of underground water to prevent the surrounding environment from pollution. On the basis of the established elastoplastic strain-hardening mechanical model considering the material's dilatancy character, the authors carry out the stress-strain analysis of a thick-wall cylinder in a plane strain state subjected to a pressure difference between internal and external pressures. The analysis may be expected to be a theoretical basis for developing a coupled shear and permeability test apparatus for conducting a permeability test along a sheared plane in a specimen. The apparatus will be used to study the effects of shear strain on the variation of geotechnical materials′ permeability coefficient in order to evaluate the influence of shear strain caused by nonuniform deformation and/or earthquake on the long-term safety of the disposal system of radioactive nuclear waste. The theoretical analysis methods in this paper can be directly spread to the analysis of the deformation and stability of tunnels or roadways driven in soft soils or high moisture-bearing soft rocks.

  1. Segmentation of the common carotid artery walls based on a frequency implementation of active contours: segmentation of the common carotid artery walls.

    Science.gov (United States)

    Bastida-Jumilla, M Consuelo; Menchón-Lara, Rosa M; Morales-Sánchez, Juan; Verdú-Monedero, Rafael; Larrey-Ruiz, Jorge; Sancho-Gómez, José Luis

    2013-02-01

    Atherosclerosis is one of the most extended cardiovascular diseases nowadays. Although it may be unnoticed during years, it also may suddenly trigger severe illnesses such as stroke, embolisms or ischemia. Therefore, an early detection of atherosclerosis can prevent adult population from suffering more serious pathologies. The intima-media thickness (IMT) of the common carotid artery (CCA) has been used as an early and reliable indicator of atherosclerosis for years. The IMT is manually computed from ultrasound images, a process that can be repeated as many times as necessary (over different ultrasound images of the same patient), but also prone to errors. With the aim to reduce the inter-observer variability and the subjectivity of the measurement, a fully automatic computer-based method based on ultrasound image processing and a frequency-domain implementation of active contours is proposed. The images used in this work were obtained with the same ultrasound scanner (Philips iU22 Ultrasound System) but with different spatial resolutions. The proposed solution does not extract only the IMT but also the CCA diameter, which is not as relevant as the IMT to predict future atherosclerosis evolution but it is a statistically interesting piece of information for the doctors to determine the cardiovascular risk. The results of the proposed method have been validated by doctors, and these results are visually and numerically satisfactory when considering the medical measurements as ground truth, with a maximum deviation of only 3.4 pixels (0.0248 mm) for IMT. PMID:22552539

  2. Changes in Water Filtration Velocity and Wall Structure of the Rabbit Common Carotid Artery after Removal of the Adventitia

    Science.gov (United States)

    Wada, Shigeo; Kaichi, Masashi; Karino, Takeshi

    To investigate the effect of the changes in water filtration velocity on the structure of an arterial wall, measurements of water filtration velocity and microscopic observation of histological specimens of the rabbit common carotid arteries were carried out by surgically removing the adventitia of the arteries and harvesting them at different times postoperatively. It was found that by removal of the adventitia, water filtration velocity at the arterial wall increased temporarily, and then as healing of the adventitia progressed, it decreased gradually until water filtration velocity attained almost the same value as that obtained with intact arteries. Intimal thickening was observed in those vessels harvested at 7 and 14 days postoperatively. Furthermore, it was shown by theoretical calculations that the concentration of low-density lipoprotein, which is a main carrier of cholesterol in blood, was locally elevated at the luminal surface of the segment where water filtration velocity was increased by removal of the adventitia. These results indicate that the change in water filtration velocity at the vessel wall brings about certain changes in the structure of the vessel wall.

  3. Wall thickness measurement using resonant phenomena of circumferential Lamb waves generated by plural transducer elements located evenly on girth

    Science.gov (United States)

    Nishino, Hideo; Iwata, Kodai; Ishikawa, Masashi

    2016-07-01

    We present a novel method of measuring the pipe wall thickness using the resonance of the circumferential (C-) Lamb wave generated by a piezoelectric ring-shaped sensor (PS). The PS is a special device for an axially propagating torsional wave; however, the C-Lamb waves are generated simultaneously as spurious signals owing to the structure of the PS. Particularly under resonant conditions, the C-Lamb waves are dominantly generated, distorting the axially propagating wave. In this method, these troublesome spurious signals are used effectively for the measurement of the wall thickness under the PS location that is a dead zone of the PS itself. The method can compensate for its drawback, namely, the dead zone problem, without using additional instruments. In this study, the mechanisms of the generation and resonance of the C-Lamb waves were first explained. Secondly, the principle of the wall thickness estimation utilizing the resonance of the C-Lamb waves was proposed. Finally, experimental verifications were carried out. The estimated wall thicknesses agreed very well (maximum 1.5% error) with those measured by a micrometer caliper under suitable resonant conditions.

  4. Male gender and sonographic gall bladder wall thickness: important predictable factors for empyema and gangrene in acute cholecystitis

    International Nuclear Information System (INIS)

    Objective: To underline the status of male gender and gall bladder wall thickness as significant risk factors for acute cholecystitis complications. Methods: The retrospective study, with purposive sampling of the patients of acute cholecystits in age above 18 years, who were operated within 10 days of onset of symptoms, was conducted at the Department of Surgery, Dow University Hospital, Karachi, by reviewing the patients' medical record from March 2010 to August 2012. Correlation of incidence of acute cholecystitis complications (empyema and gangrene) to male gender and to the sonographic gall bladder wall thickness more than 4.5mm was analysed using SPSS 16. Result: Out of 62 patients, 8 (13%) patients had gangrene while 10 (16.12%) had empyema. Overall, there were 21 (33.87%) males in the study. Ten (47.6%) of the male patients developed empyema or gangrene of the gall bladder as a complication of acute cholecystitis. Of the 41 (66.12%) female patients, only 8 (19.5%) developed these complications. There were 22 (35.48%) cases of gall bladders with sonographic wall thickness more than 4.5mm who were operated for acute cholecystitis. Of them, 16 (72.7%) had empyema or gangrene. Conclusion: Male gender and sonographic gall bladder wall thickness more than 4.5mm were statistically significant risk factors for suspicion of complicated acute cholecystitis (empyema/gangrene) and by using these risk factors, we can prioritise patients for surgery in the emergency room. (author)

  5. Chest Wall Thickness Measurements and the Dosimetric Implications for Male Workers in the South Korean Uranium Industry

    International Nuclear Information System (INIS)

    Using ultrasound techniques, the Human Monitoring Laboratory has measured chest wall thicknesses of a group of male workers at the Korea Atomic Energy Research Institute. A site-specific biometric equation has been developed for these workers, who are somewhat smaller than other workers reported in the literature. Chest wall thickness is an important modifier on lung counting efficiency. These data have been put into the perspective of the ICRP recommended dose limits for occupationally exposed workers: 100 mSv in a 5-year period with a maximum of 50 mSv in any one year. For measured chest wall thicknesses of 1.9 cm to 4.1 cm and a 30 min counting time, the achievable MDAs for natural uranium in the KAERI lung counter vary from 6.6 mg to 13.2 mg. These values are close to, or even exceed, the predicted amounts of natural uranium that will remain in the lung (absorption type M and S) after an intake equal to the Annual Limit on Intake corresponding to a committed dose of 20 mSv. This paper shows that the KAERI lung counter probably cannot detect an intake of Type S natural uranium in a worker with a chest wall thickness equal to the average value (2.7 cm) under routine counting conditions. (author)

  6. Consideration of the increasing wall thickness in inductive bendings according to KTA 3201.2 and 3201.3

    International Nuclear Information System (INIS)

    The German standards KTA 3201.2 and 3201.3 include regulations and requirements for the inductive bending. The given methodology allows an assessment of the inductive bending caused wall thickness increase effects on the global stiffness of the piping system with sufficient accuracy, even in the planning phase. The piping system calculations are performed for straight pipes and for pipe elbows and bends with approximately medium wall thicknesses. For medium size wall thicknesses the mechanical behaviour of piping systems is assessed using a best-estimate approach. In order to compensate for the wall thickness uncertainties - and other influencing factors - and the limited calculation accuracy, the standards require safety factors for allowable stresses within the system structure analyses. Since these safety factors have now influence on the attachment and component terminal loads it is recommended to include safety reserves. For dynamic analyses it is recommended to use a so-called frequency shift that compensates the influence of eigenfrequency deviations. Actually a re-evaluation is performed for implemented inductive bendings of all nuclear power plants

  7. Influence of the myocardial bridging phenomenon on the myocardial structure and the coronary arteries wall structure changes

    Directory of Open Access Journals (Sweden)

    Tomanović-Koković Jelena

    2006-01-01

    Full Text Available Background/Aim. Our research was performed to evaluate the influences of the myocardial bridging of coronary arteries on the myocardial and coronary arteries wall structure changes, that could be a reason for multiple heart malfunctions. Methods. We analyzed the autopsy material, collected during a five-years period, and especially the group of 575 cases with the major aim to diagnose mors naturalis. In all cases with the presence of myocardial bridge over the arterial coronary wall revealed at autopsy, samples were taken for microscopic verification and examination. Results. We found myocardial bridges over the coronary arteries or their major branches in 27 of the cases (4.70%. We believe that myocardial bridges compromise coronary perfusion by cyclic compression of the overbridged vessels, and that it could be the initial factor in the pathogenesis of arteriosclerotic degeneration processes on the coronary artery wall. We found different grades of arteriosclerotic changes in 88.89% of the cases, as well as fibrosis of myocardium in 88.89% and lipomatosis in 66.67% of the cases with the present myocardial bridges. Conclusion. Our results suggested that myocardial bridging of coronary arteries and/or their branches was the pathological and even lethal phenomenon that deserves more intensive clinical evaluation.

  8. Ultrasonic measurements of chest wall thickness and realistic chest phantom for calibration of Pu lung counting facilities

    International Nuclear Information System (INIS)

    There are four important problems for the measurements of chest wall thickness using ultrasonic device: (1) selection of optimum position of transducer and the number of measured points on the chest covered with detector, (2) estimation of adipose-to-muscle ratio in the chest wall, especially for dispersed adipose like 'marbled beef', (3) determination of regression equations for the prediction of chest wall thickness, derived from groups of different body shape, i.e. corpulent and lean, and (4) estimation of effective chest wall thickness involved self-absorption layer of lung tissue, which changes with distribution of activity in the lungs. This quantity can not be measured with ultrasonic device. Realistic chest phantom was developed. The phantom contains removable model organs (lungs, liver, kidneys and heart), model trachea and artificial rib cage, and also includes chest plates that can be placed over the chest to simulate wide range adipose-to-muscle ratio in the chest wall. Various soft tissue substitutes were made of polyurethane with different concentrations of additive, and the rib cage were made of epoxy resin with calcium carbonate. The experimental data have shown that the phantom can be used as a standard phantom for the calibration. (author)

  9. Low-density lipoprotein transport through an arterial wall under hyperthermia and hypertension conditions--An analytical solution.

    Science.gov (United States)

    Iasiello, Marcello; Vafai, Kambiz; Andreozzi, Assunta; Bianco, Nicola

    2016-01-25

    An analytical solution for Low-Density Lipoprotein transport through an arterial wall under hyperthermia conditions is established in this work. A four-layer model is used to characterize the arterial wall. Transport governing equations are obtained as a combination between Staverman-Kedem-Katchalsky membrane equations and volume-averaged porous media equations. Temperature and solute transport fields are coupled by means of Ludwig-Soret effect. Results are in excellent agreement with numerical and analytical literature data under isothermal conditions, and with numerical literature data for the hyperthermia case. Effects of hypertension combined with hyperthermia, are also analyzed in this work. PMID:26806687

  10. Computer modeling of tasks in dynamics of viscoelastic thin-walled elements in structures of variable thickness

    Directory of Open Access Journals (Sweden)

    R.A. Abdikarimov

    2014-08-01

    Full Text Available The paper presents a numerical method and algorithm for solving tasks in dynamics of viscoelastic thin-walled elements in structures of variable thickness. The equations of motion concerning deflections are described by partial integro-differential equations (PIDE. Using Bubnov-Galerkin’s method, based on the polynomial approximation of deflections, the task is limited to the study of the system of ordinary IDEs, where the independent variable is time. The solution to the system of IDEs is obtained by the offered numerical method, which results into the algorithm of the numerical solution and the program in the Delphi algorithmic language. The study of nonlinear vibrations of thin-walled elements in structures, allowing for variable thickness in the geometrical nonlinear statement, has enabled revealing a number of mechanical effects. Depending on physico-mechanical and geometrical parameters of the considered viscoelastic thin-walled elements in structures, the authors reccommend how to use the rigidity of the system.

  11. Numerical investigation on residual stress distribution and evolution during multipass narrow gap welding of thick-walled stainless steel pipes

    International Nuclear Information System (INIS)

    Research highlights: → We performed pass-by-pass simulation of stresses for welding of thick-walled pipes. → The distributions and evolution of the residual stresses are demonstrated. → After the groove is filled to a height, the through-wall stress is almost unchanged. - Abstracts: The detailed pass-by-pass finite element (FE) simulation is presented to investigate the residual stresses in narrow gap multipass welding of pipes with a wall thickness of 70 mm and 73 weld passes. The simulated residual stress on the outer surface is validated with the experimental one. The distribution and evolution of the through-wall residual stresses are demonstrated. The investigated results show that the residual stresses on the outer and inner surfaces are tensile in the weld zone and its vicinity. The through-wall axial residual stresses at the weld center line and the HAZ line demonstrate a distribution of bending type. The through-wall hoop residual stress within the weld is mostly tensile. After the groove is filled to a certain height, the peak tensile stresses and the stress distribution patterns for both axial and hoop stresses remain almost unchanged.

  12. Current-induced domain wall motion in Co/Ni nano-wires with different Co and Ni thicknesses

    International Nuclear Information System (INIS)

    The authors have investigated magnetic domain wall motion induced by electric currents in ferromagnetic nano-wires made of Co/Ni multilayers. The thicknesses of Co and Ni layers were changed, whereas the numbers of layer stacks of Co and Ni were the same in all samples. The sample with thinner total Co/Ni thickness showed the lower threshold current density for the domain wall motion as an overall trend, which is qualitatively in agreement with the expectation by the theory based on the adiabatic spin-transfer model. The lowest threshold current density was 2.9x1011 A/m2 obtained in the sample with the total Co/Ni thickness of 3.4 nm and the wire width of 110 nm.

  13. Multislice helical CT analysis of small-sized airway wall thickness in smokers and patients with bronchial asthma

    International Nuclear Information System (INIS)

    There is accumulating evidence that airway remodeling, which contributes to airway narrowing, plays a role in the pathogenesis of bronchial asthma (BA) and chronic obstructive pulmonary disease (COPD). Development of the multislice helical CT (MSCT) with improved spatial resolution has made it possible to obtain more precise imaging of small-sized airways. Small-sized airway wall-thickness was measured using the MSCT scan to analyze small-sized airways of smokers and BA patients, and examine the effects of a β2 agonists on small-sized airway wall-thickness of BA patients. Thirty-six non-asthmatics who participated in the Health Check Program of Iwate Medical University and 25 patients with asthma were recruited. Amongst the 36 non-asthmatics were 20 healthy never-smokers and 15 smokers. The other 25 asthmatics were recruited from the outpatient clinic at Iwate Medical University. MSCT was performed and the right B10 bronchus was chosen for dimensional analysis. Airway wall thickness was expressed as a percentage of wall area (WA%). WA% of the 7 asthmatics before and 30 mim after procaterol (20μg) inspiration were compared. Small-sized airway wall thickness was significantly increased in smokers and patients with asthma compared to healthy never-smokers, when determined by MSCT. Both %V50 and %V25 had significant negative correlations with WA% among the healthy never-smokers and smoker population. Procaterol inspiration reduced WA% in the small airway of patients with asthma. Increase of small-sized airway thickness measured by MSCT scan may reflect peripheral obstructive lesions of smokers and BA patients. (author)

  14. A prospective cohort study of the long-term effects of CPAP on carotid artery intima-media thickness in Obstructive sleep apnea syndrome

    Directory of Open Access Journals (Sweden)

    Hui David S

    2012-03-01

    Full Text Available Abstract Objective To examine the long-term effect of CPAP on carotid artery intima-media thickness (IMT in patients with Obstructive sleep apnea syndrome(OSAS. Methods A prospective observational study over 12 months at a teaching hospital on 50 patients newly diagnosed with OSAS who received CPAP or conservative treatment (CT. Carotid IMT was assessed with B-mode Doppler ultrasound from both carotid arteries using images of the far wall of the distal 10 mm of the common carotid arteries at baseline, 6 months and 12 months. Measurements and results [mean (SE] Altogether 28 and 22 patients received CPAP and CT respectively without significant differences in age 48.8(1.8 vs 50.5(2.0yrs, BMI 28.2(0.7 vs 28.0(1.2kg/m2, ESS 13.1(0.7 vs 12.7(0.6, AHI 38(3 vs 39(3/hr, arousal index 29(2 vs 29(2/hr, minimum SaO2 75(2 vs 77(2% and existing co-morbidities. CPAP usage was 4.6(0.3 and 4.7(0.4hrs/night over 6 months and 1 year respectively. Carotid artery IMT at baseline, 6 months, and 12 months were 758(30, 721(20, and 705(20micron for the CPAP group versus 760(30, 770(30, and 778(30micron respectively for the CT group, p = 0.002. Among those free of cardiovascular disease(n = 24, the carotid artery IMT at baseline, 6 months and 12 months were 722(40, 691(40, and 659(30micron for the CPAP group (n = 12 with usage 4.5(0.7 and 4.7(0.7 hrs/night over 6 months and 12 months whereas the IMT data for the CT group(n = 12 were 660(20, 685(10, and 690(20micron respectively, p = 0.006. Conclusions Reduction of carotid artery IMT occurred mostly in the first 6 months and was sustained at 12 months in patients with reasonable CPAP compliance.

  15. Prevalence and prognosis of myocardial scar in patients with known or suspected coronary artery disease and normal wall motion

    OpenAIRE

    Boonyasirinant Thananya; Saiviroonporn Pairash; Krittayaphong Rungroj; Udompunturak Suthipol

    2011-01-01

    Abstract Background Some patients may have normal wall motion after myocardial infarction. The aim of this study was to determine the prevalence and prognosis of patients with myocardial scar in the absence of abnormal wall motion. We studied patients with suspected or known coronary artery disease (CAD) who were referred for cardiovascular magnetic resonance (CMR) for the assessment of global and regional cardiac function and late gadolinium enhancement (LGE) and had normal left ventricular ...

  16. Increased infarct wall thickness by a bio-inert material is insufficient to prevent negative left ventricular remodeling after myocardial infarction.

    Directory of Open Access Journals (Sweden)

    Aboli A Rane

    Full Text Available BACKGROUND: Several injectable materials have been shown to preserve or improve cardiac function as well as prevent or slow left ventricular (LV remodeling post-myocardial infarction (MI. However, it is unclear as to whether it is the structural support or the bioactivity of these polymers that lead to beneficial effects. Herein, we examine how passive structural enhancement of the LV wall by an increase in wall thickness affects cardiac function post-MI using a bio-inert, non-degradable synthetic polymer in an effort to better understand the mechanisms by which injectable materials affect LV remodeling. METHODS AND RESULTS: Poly(ethylene glycol (PEG gels of storage modulus G' = 0.5±0.1 kPa were injected and polymerized in situ one week after total occlusion of the left coronary artery in female Sprague Dawley rats. The animals were imaged using magnetic resonance imaging (MRI at 7±1 day(s post-MI as a baseline and again post-injection 49±4 days after MI. Infarct wall thickness was statistically increased in PEG gel injected vs. control animals (p<0.01. However, animals in the polymer and control groups showed decreases in cardiac function in terms of end diastolic volume, end systolic volume and ejection fraction compared to baseline (p<0.01. The cellular response to injection was also similar in both groups. CONCLUSION: The results of this study demonstrate that passive structural reinforcement alone was insufficient to prevent post-MI remodeling, suggesting that bioactivity and/or cell infiltration due to degradation of injectable materials are likely playing a key role in the preservation of cardiac function, thus providing a deeper understanding of the influencing properties of biomaterials necessary to prevent post-MI negative remodeling.

  17. Altered Metabolism of LDL in the Arterial Wall Precedes Atherosclerosis Regression

    DEFF Research Database (Denmark)

    Bartels, Emil D.; Christoffersen, Christina; Lindholm, Marie W.;

    2015-01-01

    % already after 1 week of treatment despite an unchanged pool size of aortic iodinated LDL particles. In contrast, the size, foam cell content, and aortic pool size of iodinated LDL particles of aortic atherosclerotic plaques were not reduced until after 4 weeks of treatment with the anti-Apob antisense...... and degradation of LDL particles in atherosclerotic aortas of mice by measuring the accumulation of iodinated LDL particles in the arterial wall. Methods and Results: Cholesterol-fed, LDL receptor–deficient mice were treated with either an anti-Apob antisense oligonucleotide or a mismatch control...... antisense oligonucleotide once a week for 1 or 4 weeks before injection with preparations of iodinated LDL particles. The anti-Apob antisense oligonucleotide reduced plasma cholesterol by ≈90%. The aortic LDL permeability and degradation rates of newly entered LDL particles were reduced by ≈50% and ≈85...

  18. Ultrasonic measurements on residual stress in autofrettged thick walled petroleum pipes

    International Nuclear Information System (INIS)

    The residual stresses in a component or structure are caused by incompatible permanent deformation and related gradient of plastic/elastic strains. They may be generated or modified at every stage in the components life cycle, from original material production to final disposal. Residual stresses can be measured by non-destructive techniques, including X-ray and neutron diffraction, magnetic and ultrasonic methods. The selection of the optimum measurement technique should take account volumetric resolution, material, geometry and access to the component. For large metallic components neutron diffraction is of prime importance as it provides quantitative information on stresses in relatively large volume of methods disregarding its shape complexity. Residual stresses can play a significant role in explaining or preventing failure of components of industrial installations. One example of residual stresses preventing failure are the ones generated by shot peening, inducing surface compressive stresses that improve the fatigue life. Petroleum refinery piping is generally characterized by large-diameters, operated at elevated temperature and under high pressure. Pipelines of a polyethylene plant working in one of the Polish refineries are subjected to pressures exceeding 300 MPa at temperatures above 200oC. The pipes considered here were pressurized with pressure of 600 MPa. The wall thickness of the pipes is 27 mm and pipe dimensions are 46 x 100 mm. The material is steel with Re=580 MPa. Due to pressurizing, the components retain compressive stresses at the internal surface. These stresses increase resistance to cracking of the pipes. Over the period of exploitation these stresses diminish due to temperature activated relaxation or creep. The purpose of the project is to verify kinetics of such a relaxation process and calibrate alternative methods of their measurements. To avoid stress relaxation, numerical analysis from Finite Element Modelling (FEM)gave an optimal

  19. Structural alterations of the coronary arterial wall are associated with myocardial flow heterogeneity in type 2 diabetes mellitus

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Thomas H. [California Univ., Los Angeles, CA (United States). Dept. of Moelecular and Medical Pharmacology, Radiological Science]|[University Hospital of Geneva, Department of Internal Medicine, Cardiovascular Center, Nuclear Cardiology, Geneva (Switzerland); Facta, Alvaro D.; Prior, John O.; Cadenas, Jerson; Zhang, Xiao-Li; Sayre, James; Goldin, Jonathan; Schelbert, Heinrich R. [California Univ., Los Angeles, CA (United States). Dept. of Moelecular and Medical Pharmacology, Radiological Science; Li, Yanjie [University of Southern California, Atherosclerosis Research Unit, Keck School of Medicine, Los Angeles, CA (United States)

    2009-02-15

    To determine the relationship between carotid intima-media thickness (IMT), coronary artery calcification (CAC), and myocardial blood flow (MBF) at rest and during vasomotor stress in type 2 diabetes mellitus (DM). In 68 individuals, carotid IMT was measured using high-resolution vascular ultrasound, while the presence of CAC was determined with electron beam tomography (EBT). Global and regional MBF was determined in milliliters per gram per minute with {sup 13}N-ammonia and positron emission tomography (PET) at rest, during cold pressor testing (CPT), and during adenosine (ADO) stimulation. There was neither a relationship between carotid IMT and CAC (r = 0.10, p = 0.32) nor between carotid IMT and coronary circulatory function in response to CPT and during ADO (r = -0.18, p = 0.25 and r = 0.10, p = 0.54, respectively). In 33 individuals, EBT detected CAC with a mean Agatston-derived calcium score of 44 {+-} 18. There was a significant difference in regional MBFs between territories with and without CAC at rest and during ADO-stimulated hyperemia (0.69 {+-} 0.24 vs. 0.74 {+-} 0.23 and 1.82 {+-} 0.50 vs. 1.95 {+-} 0.51 ml/g/min; p {<=} 0.05, respectively) and also during CPT in DM but less pronounced (0.81 {+-} 0.24 vs. 0.83 {+-} 0.23 ml/g/min; p = ns). The increase in CAC was paralleled with a progressive regional decrease in resting as well as in CPT- and ADO-related MBFs (r = -0.36, p {<=} 0.014; r = -0.46, p {<=} 0.007; and r = -0.33, p {<=} 0.041, respectively). The absence of any correlation between carotid IMT and coronary circulatory function in type 2 DM suggests different features and stages of early atherosclerosis in the peripheral and coronary circulation. PET-measured MBF heterogeneity at rest and during vasomotor stress may reflect downstream fluid dynamic effects of coronary artery disease (CAD)-related early structural alterations of the arterial wall. (orig.)

  20. Structural alterations of the coronary arterial wall are associated with myocardial flow heterogeneity in type 2 diabetes mellitus

    International Nuclear Information System (INIS)

    To determine the relationship between carotid intima-media thickness (IMT), coronary artery calcification (CAC), and myocardial blood flow (MBF) at rest and during vasomotor stress in type 2 diabetes mellitus (DM). In 68 individuals, carotid IMT was measured using high-resolution vascular ultrasound, while the presence of CAC was determined with electron beam tomography (EBT). Global and regional MBF was determined in milliliters per gram per minute with 13N-ammonia and positron emission tomography (PET) at rest, during cold pressor testing (CPT), and during adenosine (ADO) stimulation. There was neither a relationship between carotid IMT and CAC (r = 0.10, p = 0.32) nor between carotid IMT and coronary circulatory function in response to CPT and during ADO (r = -0.18, p = 0.25 and r = 0.10, p = 0.54, respectively). In 33 individuals, EBT detected CAC with a mean Agatston-derived calcium score of 44 ± 18. There was a significant difference in regional MBFs between territories with and without CAC at rest and during ADO-stimulated hyperemia (0.69 ± 0.24 vs. 0.74 ± 0.23 and 1.82 ± 0.50 vs. 1.95 ± 0.51 ml/g/min; p ≤ 0.05, respectively) and also during CPT in DM but less pronounced (0.81 ± 0.24 vs. 0.83 ± 0.23 ml/g/min; p = ns). The increase in CAC was paralleled with a progressive regional decrease in resting as well as in CPT- and ADO-related MBFs (r = -0.36, p ≤ 0.014; r = -0.46, p ≤ 0.007; and r = -0.33, p ≤ 0.041, respectively). The absence of any correlation between carotid IMT and coronary circulatory function in type 2 DM suggests different features and stages of early atherosclerosis in the peripheral and coronary circulation. PET-measured MBF heterogeneity at rest and during vasomotor stress may reflect downstream fluid dynamic effects of coronary artery disease (CAD)-related early structural alterations of the arterial wall. (orig.)

  1. Bladder wall thickness and ultrasound estimated bladder weight in healthy adults with portative ultrasound device

    Directory of Open Access Journals (Sweden)

    Selcen Kanyilmaz

    2013-01-01

    Full Text Available Background: The aim of this study was to investigate bladder wall thickness (BWT and ultrasound estimated bladder weight (UEBW values in healthy population with a portative ultrasound device and their relationship with demographic parameters. Materials and Methods: The study was carried out in Neurorehabilitation Clinic of Ege University Hospital. Ninety-five subjects (48 women and 47 men aged between 18 and 56 were included in the study. BWT and UEBW were determined non-invasively with a portative ultrasound device; Bladder Scan BVM 6500 (Verathon Inc., WA, USA at a frequency of 3.7 MHz at functional bladder capacity. These values were compared by gender, and their relation was assessed with age, body mass index (BMI and parity. Results: Mean BWT was 2.0 ± 0.4 mm and UEBW was 44.6 ± 8.3 g at a mean volume of 338.0 ± 82.1 ml. Although higher results were obtained in men at higher bladder volumes, the results did not differ significantly by gender. Correlation analyses revealed statistically significant correlation between UEBW and age (r = 0.32. BWT was negatively correlated with volume (r = -0.50 and bladder surface area (r = -0.57. Also, statistically significant correlations were observed between UEBW and volume (r = 0.36, bladder surface area (r = 0.48 and BWT (r = 0.25. Conclusion: Determined values of BWT and UEBW in healthy population are estimated with portative ultrasound devices, which are future promising, for their convenient, easy, non-invasive, time-efficient hand-held use for screening.

  2. The thick left ventricular wall of the giraffe heart normalises wall tension, but limits stroke volume and cardiac output

    DEFF Research Database (Denmark)

    Smerup, Morten Holdgaard; Damkjær, Mads; Brøndum, Emil; Baandrup, Ulrik T.; Kristiansen, Steen Buus; Nygaard, Hans; Aalkjær, Christian; Sauer, Cathrine; Buchanan, Rasmus; Bertelsen, Mads Frost; Østergaard, Kristine Hovkjær; Grøndahl, Carsten; Candy, Geoffrey; Hasenkam, J Michael; Secher, Niels H; Bie, Peter; Wang, Tobias

    2015-01-01

    pressures to calculate left ventricular wall stress. Cardiac output was also determined by inert gas rebreathing to provide an additional and independent estimate of stroke volume. Echocardiography and inert gas-rebreathing yielded similar cardiac outputs of 16.1±2.5 and 16.4±1.4 l min(-1), respectively...

  3. Medical decision-making system of ultrasound carotid artery intima-media thickness using neural networks.

    Science.gov (United States)

    Santhiyakumari, N; Rajendran, P; Madheswaran, M

    2011-12-01

    The objective of this work is to develop and implement a medical decision-making system for an automated diagnosis and classification of ultrasound carotid artery images. The proposed method categorizes the subjects into normal, cerebrovascular, and cardiovascular diseases. Two contours are extracted for each and every preprocessed ultrasound carotid artery image. Two types of contour extraction techniques and multilayer back propagation network (MBPN) system have been developed for classifying carotid artery categories. The results obtained show that MBPN system provides higher classification efficiency, with minimum training and testing time. The outputs of decision support system are validated with medical expert to measure the actual efficiency. MBPN system with contour extraction algorithms and preprocessing scheme helps in developing medical decision-making system for ultrasound carotid artery images. It can be used as secondary observer in clinical decision making. PMID:21181487

  4. Medical Decision-Making System of Ultrasound Carotid Artery Intima–Media Thickness Using Neural Networks

    OpenAIRE

    N. Santhiyakumari; Rajendran, P.; M. Madheswaran

    2010-01-01

    The objective of this work is to develop and implement a medical decision-making system for an automated diagnosis and classification of ultrasound carotid artery images. The proposed method categorizes the subjects into normal, cerebrovascular, and cardiovascular diseases. Two contours are extracted for each and every preprocessed ultrasound carotid artery image. Two types of contour extraction techniques and multilayer back propagation network (MBPN) system have been developed for classifyi...

  5. Bobbin-Tool Friction-Stir Welding of Thick-Walled Aluminum Alloy Pressure Vessels

    Energy Technology Data Exchange (ETDEWEB)

    Dalder, E C; Pastrnak, J W; Engel, J; Forrest, R S; Kokko, E; Ternan, K M; Waldron, D

    2007-06-06

    It was desired to assemble thick-walled Al alloy 2219 pressure vessels by bobbin-tool friction-stir welding. To develop the welding-process, mechanical-property, and fitness-for-service information to support this effort, extensive friction-stir welding-parameter studies were conducted on 2.5 cm. and 3.8 cm. thick 2219 Al alloy plate. Starting conditions of the plate were the fully-heat-treated (-T62) and in the annealed (-O) conditions. The former condition was chosen with the intent of using the welds in either the 'as welded' condition or after a simple low-temperature aging treatment. Since preliminary stress-analyses showed that stresses in and near the welds would probably exceed the yield-strength of both 'as welded' and welded and aged weld-joints, a post-weld solution-treatment, quenching, and aging treatment was also examined. Once a suitable set of welding and post-weld heat-treatment parameters was established, the project divided into two parts. The first part concentrated on developing the necessary process information to be able to make defect-free friction-stir welds in 3.8 cm. thick Al alloy 2219 in the form of circumferential welds that would join two hemispherical forgings with a 102 cm. inside diameter. This necessitated going to a bobbin-tool welding-technique to simplify the tooling needed to react the large forces generated in friction-stir welding. The bobbin-tool technique was demonstrated on both flat-plates and plates that were bent to the curvature of the actual vessel. An additional issue was termination of the weld, i.e. closing out the hole left at the end of the weld by withdrawal of the friction-stir welding tool. This was accomplished by friction-plug welding a slightly-oversized Al alloy 2219 plug into the termination-hole, followed by machining the plug flush with both the inside and outside surfaces of the vessel. The second part of the project involved demonstrating that the welds were fit for the intended

  6. Sarcocystis sinensis is the most prevalent thick-walled Sarcocystis species in beef on sale for consumers in Germany.

    Science.gov (United States)

    Moré, G; Pantchev, A; Skuballa, J; Langenmayer, M C; Maksimov, P; Conraths, F J; Venturini, M C; Schares, G

    2014-06-01

    Bovines are intermediate hosts of Sarcocystis cruzi, Sarcocystis hirsuta, and Sarcocystis hominis, which use canids, felids, or primates as definitive hosts, respectively. Cattle represent also intermediate hosts of Sarcocystis sinensis, but the definitive hosts of this parasite are not yet known. Sarcocystosis in cattle is frequently asymptomatic. The infection is characterized by the presence of thin-walled (S. cruzi) or thick-walled muscle cysts or sarcocysts (S. hominis, S. sinensis, and S. hirsuta). Recent reports suggest high prevalence of the zoonotic S. hominis in beef in Europe. We therefore aimed at differentiating Sarcocystis spp. in beef offered to consumers in Germany using molecular and microscopical methods, focusing on those species producing thick-walled sarcocysts. A total of 257 beef samples were obtained from different butcheries and supermarkets in Germany and processed by conventional and multiplex real-time PCR. In addition, 130 of these samples were processed by light microscopy and in 24.6% thick-walled cysts were detected. Transmission electron microscopical analysis of six of these samples revealed an ultrastructural cyst wall pattern compatible with S. sinensis in five samples and with S. hominis in one sample. PCR-amplified 18S ribosomal DNA (rDNA) fragments of 28 individual thick-walled cysts were sequenced, and sequence identities of ≥98% with S. sinensis (n = 22), S. hominis (n = 5) and S. hirsuta (n = 1) were observed. Moreover, nine Sarcocystis sp. 18S rDNA full length gene sequences were obtained, five of S. sinensis, three of S. hominis, and one of S. hirsuta. Out of all samples (n = 257), 174 (67.7%) tested positive by conventional PCR and 179 (69.6%) by multiplex real-time PCR for Sarcocystis spp. Regarding individual species, 134 (52%), 95 (37%), 17 (6.6%), and 16 (6.2%) were positive for S. cruzi, S. sinensis, S. hirsuta, and S. hominis, respectively. In conclusion, S. sinensis is the most prevalent thick-walled

  7. Bilateral common carotid artery ultrasound for prediction of incident strokes using intima-media thickness and external diameter: an observational study

    OpenAIRE

    Eigenbrodt, Marsha L.; Evans, Gregory W.; Rose, Kathryn M; Bursac, Zoran; Tracy, Richard E.; Mehta, Jawahar L.; Couper, David J

    2013-01-01

    Background External common carotid artery (CCA) diameter and intima-media thickness (IMT) are independently associated with incident stroke and other cardiovascular events. Arterial geometry such as large IMT and large diameter may reflect vulnerable plaques and so impact stroke risk. Finally, arterial changes that exist bilaterally may increase stroke risk. Method We studied middle-aged men and women (n=7276) from a prospective observational study who had right (R) and left (L) CCA IMT and e...

  8. Numerical study of wall shear stress-based descriptors in the human left coronary artery.

    Science.gov (United States)

    Pinto, S I S; Campos, J B L M

    2016-10-01

    The present work is about the application of wall shear stress descriptors - time averaged wall shear stress (TAWSS), oscillating shear index (OSI) and relative residence time (RRT) - to the study of blood flow in the left coronary artery (LCA). These descriptors aid the prediction of disturbed flow conditions in the vessels and play a significant role in the detection of potential zones of atherosclerosis development. Hemodynamic descriptors data were obtained, numerically, through ANSYS® software, for the LCA of a patient-specific geometry and for a 3D idealized model. Comparing both cases, the results are coherent, in terms of location and magnitude. Low TAWSS, high OSI and high RRT values are observed in the bifurcation - potential zone of atherosclerosis appearance. The dissimilarities observed in the TAWSS values, considering blood as a Newtonian or non-Newtonian fluid, releases the importance of the correct blood rheologic caracterization. Moreover, for a higher Reynolds number, the TAWSS values decrease in the bifurcation and along the LAD branch, increasing the probability of plaques deposition. Furthermore, for a stenotic LCA model, very low TAWSS and high RRT values in front and behind the stenosis are observed, indicating the probable extension, in the flow direction, of the lesion. PMID:26883291

  9. Biometric estimation of chest wall thickness of female radiation workers as an aid in in-vivo detection of the actinides

    International Nuclear Information System (INIS)

    An equation was derived to estimate female chest wall thickness from a series of biometric measurements. This technique will result in improved performance for actinide detection in females by accounting for variations in chest wall thickness in derivation of calibration factors

  10. Determination of site-specific carotid-intima media thickness: common –carotid artery and carotid bifurcation in hypercholesterolemia patients

    OpenAIRE

    Perwaiz Khan, Samia; Gul, Pashmina; Khemani, Saleem; Yaqub, Zia

    2013-01-01

    Objective: To determine site specific carotid intima-media thickness: common–carotid artery and carotid bifurcation in hypercholesterolemia patients as a marker for atherosclerosis. Methods: Fifty patients with hypercholesterolemia and twenty controls were selected after getting informed consent regarding the investigation of carotid- intima media thickness by B-mode ultrasound. All the patients of hypercholesterolemia with LDL-C > 160mg/dL had family history of coronary artery diseases. This...

  11. Development of pipe wall thinning measurement technology using radiation. Introduction of performance testing of pipe wall thickness measurement technology contributing to labor saving and high precision for pipe wall thinning management with thermal insulator outside

    International Nuclear Information System (INIS)

    Pipe wall thickness measurement equipment using radioisotope (Cs-137) and high sensitive scintillation counter (CsI(Tl)) had been applied for pipes with stagnant water inside and thermal insulator outside. Thickness measurement performance testing was conducted for verification of the equipment, with standard deviation 0.1 mm for 100 sec measurement. Pipe wall thinning measurement with and without thermal insulator was performed with ±0.4 mm tolerance for corrosion thinning inside or outside. The equipment measuring the level of stagnant water inside pipes within ±0.2 mm tolerance was also developed to obtain correction factor dependent on water level for pipe wall thickness measurement. Pipe wall thinning measurement with stagnant water inside for thermal insulator outside was performed within ±0.5 mm tolerance. Thus, thickness measurement for pipes with thermal insulators outside and stagnant water inside were demonstrated within allowable tolerance, which could contribute to labor saving and high precision for pipe wall thinning management. (T. Tanaka)

  12. Arterial stick

    Science.gov (United States)

    ... the main arteries in the forearm (radial and ulnar arteries). The procedure is done as follows: The ... Arteries also have thicker walls and have more nerves. When the needle is inserted, there may be ...

  13. Mathematical modeling of coupled drug and drug-encapsulated nanoparticle transport in patient-specific coronary artery walls

    KAUST Repository

    Hossain, Shaolie S.

    2011-08-20

    The majority of heart attacks occur when there is a sudden rupture of atherosclerotic plaque, exposing prothrombotic emboli to coronary blood flow, forming clots that can cause blockages of the arterial lumen. Diseased arteries can be treated with drugs delivered locally to vulnerable plaques. The objective of this work was to develop a computational tool-set to support the design and analysis of a catheter-based nanoparticulate drug delivery system to treat vulnerable plaques and diffuse atherosclerosis. A threedimensional mathematical model of coupled mass transport of drug and drug-encapsulated nanoparticles was developed and solved numerically utilizing isogeometric finite element analysis. Simulations were run on a patient-specific multilayered coronary artery wall segment with a vulnerable plaque and the effect of artery and plaque inhomogeneity was analyzed. The method captured trends observed in local drug delivery and demonstrated potential for optimizing drug design parameters, including delivery location, nanoparticle surface properties, and drug release rate. © Springer-Verlag 2011.

  14. Batch processing of geometric parameters and wall thickness distribution calculation of ICF capsule by X-ray imaging method

    International Nuclear Information System (INIS)

    The basic principle of micro-focus X-ray imaging was analyzed. An improved Hough transform method was applied to automatically detect circle parameters of the capsule X-ray digital image, and precise multi-layer capsule geometric parameters were obtained by combining the least squares circle fitting algorithm. The whole image analysis procedure of batch processing was also introduced and a complete capsule X-ray image batch computing software was developed. The wall thickness distribution of the capsule batch calculation was discussed based on the above work. Some examples of the wall thickness distribution of a multi-layer capsule and the whole surface distribution of a monolayer capsule were calculated. This work will contribute to the rapid automatic capsule geometry measurement, and provide more detailed capsule geometry parameters to meet the growing requirements of target fabrication tasks. (authors)

  15. Quantification of myocardial delayed enhancement and wall thickness in hypertrophic cardiomyopathy: Multidetector computed tomography versus magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Lei [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, No. 2 Anzhen Rd Beijing (China); Ma, Xiaohai, E-mail: maxi8238@gmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, No. 2 Anzhen Rd Beijing (China); Feuchtner, Gudrun Maria [Department of Radiology II, Innsbruck Medical University, Innsbruck (Austria); Zhang, Chen; Fan, Zhanming [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, No. 2 Anzhen Rd Beijing (China)

    2014-10-15

    Objectives: To evaluate the accuracy of multidetector computed tomography (MDCT) in assessing myocardial delayed enhancement and left ventricle wall thickness in hypertrophic cardiomyopathy (HCM) compared with cardiac magnetic resonance (CMR) as the reference standard. Materials and methods: Eighty consecutive patients (59 male; 53.2 ± 13.0 years) were examined with MDCT, followed by CMR 1 day later. Cardiac CT angiography and a delayed CT were performed. CMR was performed according to a standardized protocol. Left ventricle wall thickness and positions of myocardial delayed enhancement were identified in both CMR and CT images according to the American Heart Association left ventricle 17-segment model. Myocardial delayed enhancement was characterized as “dense” (areas with clear defined borders) or “diffuse” and then quantified using both techniques. Results: Left ventricle wall thickness determined by MDCT was significantly correlated with CMR (R = 0.88, P < 0.01). Compared with CMR, MDCT accurately diagnosed 74 of 78 (94.9%) patients and 1243 of 1326 (93.7%) segments. For dense myocardial delayed enhancement, MDCT significantly correlated with CMR (R = 0.88, P < 0.01) and slightly underestimated myocardial delayed enhancement (mean, −3.85%; lower and upper limits of agreement, −13.40% and 5.70%, respectively). Conclusions: MDCT provides reliable quantification of myocardial delayed enhancement and evaluation of left ventricle wall thickness and has a good correlation with CMR in patients with HCM when a comprehensive cardiac CT protocol is used and can be applied for intervention planning.

  16. Chest-wall thickness and percent thoracic fat estimation by B-mode ultrasound: system and procedure review

    International Nuclear Information System (INIS)

    Accurate measurement of chest wall thickness is necessary for estimation of lung burden of transuranic elements in humans. To achieve tis capability, the ORNL Whole Body Counter has acquired a B-mode ultrasonic imaging system for defining the structure within the thorax of the body. This report contains a review of the ultrasound system in use at the ORNL Whole Body Counter, including its theory of operation, and te procedure for use of the system. Future developmental plans are also presented

  17. Quantification of myocardial delayed enhancement and wall thickness in hypertrophic cardiomyopathy: Multidetector computed tomography versus magnetic resonance imaging

    International Nuclear Information System (INIS)

    Objectives: To evaluate the accuracy of multidetector computed tomography (MDCT) in assessing myocardial delayed enhancement and left ventricle wall thickness in hypertrophic cardiomyopathy (HCM) compared with cardiac magnetic resonance (CMR) as the reference standard. Materials and methods: Eighty consecutive patients (59 male; 53.2 ± 13.0 years) were examined with MDCT, followed by CMR 1 day later. Cardiac CT angiography and a delayed CT were performed. CMR was performed according to a standardized protocol. Left ventricle wall thickness and positions of myocardial delayed enhancement were identified in both CMR and CT images according to the American Heart Association left ventricle 17-segment model. Myocardial delayed enhancement was characterized as “dense” (areas with clear defined borders) or “diffuse” and then quantified using both techniques. Results: Left ventricle wall thickness determined by MDCT was significantly correlated with CMR (R = 0.88, P < 0.01). Compared with CMR, MDCT accurately diagnosed 74 of 78 (94.9%) patients and 1243 of 1326 (93.7%) segments. For dense myocardial delayed enhancement, MDCT significantly correlated with CMR (R = 0.88, P < 0.01) and slightly underestimated myocardial delayed enhancement (mean, −3.85%; lower and upper limits of agreement, −13.40% and 5.70%, respectively). Conclusions: MDCT provides reliable quantification of myocardial delayed enhancement and evaluation of left ventricle wall thickness and has a good correlation with CMR in patients with HCM when a comprehensive cardiac CT protocol is used and can be applied for intervention planning

  18. The haptoglobin 2-2 genotype is associated with inflammation and carotid artery intima-media thickness.

    Science.gov (United States)

    Dalan, Rinkoo; Liew, Huiling; Goh, Liuh Ling; Gao, Xiao; Chew, Daniel Ek; Boehm, Bernhard O; Leow, Melvin Khee Shing

    2016-09-01

    The haptoglobin 2-2 genotype is associated with atherosclerosis in type 2 diabetes mellitus. We examined the associations of the haptoglobin 2-2 genotype with C-reactive protein (high-sensitivity C-reactive protein) and carotid artery intima-media thickness, adjusting for age, gender, ethnicity, type 2 diabetes mellitus, smoking status, body mass index, blood pressure, glycated haemoglobin, non-high-density lipoprotein cholesterol and medications via logistic multivariate regression in 200 subjects (160 type 2 diabetes mellitus versus 40 healthy individuals). The prevalence of the haptoglobin 2-2 genotype was 58% (115/200), higher in the Indians than in Chinese (72% versus 45%, p = 0.001). Multivariate analysis showed that the haptoglobin 2-2 genotype was associated with high-sensitivity C-reactive protein [mean: 3.5 ± 3.9 versus 2.2 ± 2.6 mg/L (non-haptoglobin 2-2), p < 0.001], haptoglobin concentration [mean: 116.9 ± 54.4.0 versus 147.2 ± 54.5 mg/dL (non-haptoglobin 2-2), p < 0.001] and average carotid artery intima-media thickness (multiplied by 10) [6.15 ± 1.22 versus 5.98 ± 1.20 mm (non-haptoglobin 2-2), p = 0.013]. This pilot study shows an association of the haptoglobin 2-2 genotype with low-grade inflammation, haptoglobin concentration and carotid artery intima-media thickness in multi-ethnic Singapore. PMID:27190085

  19. Shear flow over a plane wall with an axisymmetric cavity or a circular orifice of finite thickness

    International Nuclear Information System (INIS)

    Shear flow over a plane wall that contains an axisymmetric depression or pore is studied using a new boundary integral method which is suitable for computing three-dimensional Stokes flow within axisymmetric domains. Numerical results are presented for cavities in the shape of a section of a sphere or a circular cylinder of finite length, and for a family of pores or orifices with finite thickness. The results illustrate the distribution of shear stresses over the plane wall and inside the cavities or pores. It is found that in most cases, the distribution of shear stresses over the plane wall, around the depressions, is well approximated with that for flow over an orifice of infinitesimal thickness for which an exact solution is available. The kinematic structure of the flow is discussed with reference to eddy formation and three-dimensional flow reversal. It is shown that the thickness of a circular orifice or depth of a pore play an important role in determining the kinematical structure of the flow underneath the orifice in the lower half-space

  20. Bulk and boundary critical behaviour of thin and thick domain walls in the two-dimensional Potts model

    International Nuclear Information System (INIS)

    The geometrical critical behaviour of the two-dimensional Q-state Potts model is usually studied in terms of the Fortuin–Kasteleyn (FK) clusters, or their surrounding loops. In this paper we study a quite different geometrical object: the spin clusters, defined as connected domains where the spin takes a constant value. Unlike the usual loops, the domain walls separating different spin clusters can cross and branch. Moreover, they come in two versions, 'thin' or 'thick', depending on whether they separate spin clusters of different or identical colours. For these reasons their critical behaviour is different from, and richer than, those of FK clusters. We develop a transfer matrix technique enabling the formulation and numerical study of spin clusters even when Q is not an integer. We further identify geometrically the crossing events which give rise to conformal correlation functions. We study the critical behaviour both in the bulk, and at a boundary with free, fixed, or mixed boundary conditions. This leads to infinite series of fundamental critical exponents, hl1-l2,2l1 in the bulk and h1+2(l1-l2),1+4l1 at the boundary, valid for 0 ≤ Q ≤ 4, that describe the insertion of l1 thin and l2 thick domain walls. We argue that these exponents imply that the domain walls are 'thin' and 'thick' also in the continuum limit. A special case of the bulk exponents is derived analytically from a massless scattering approach

  1. Automated registration of multispectral MR vessel wall images of the carotid artery

    Energy Technology Data Exchange (ETDEWEB)

    Klooster, R. van ' t; Staring, M.; Reiber, J. H. C.; Lelieveldt, B. P. F.; Geest, R. J. van der, E-mail: rvdgeest@lumc.nl [Department of Radiology, Division of Image Processing, Leiden University Medical Center, 2300 RC Leiden (Netherlands); Klein, S. [Department of Radiology and Department of Medical Informatics, Biomedical Imaging Group Rotterdam, Erasmus MC, Rotterdam 3015 GE (Netherlands); Kwee, R. M.; Kooi, M. E. [Department of Radiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht 6202 AZ (Netherlands)

    2013-12-15

    Purpose: Atherosclerosis is the primary cause of heart disease and stroke. The detailed assessment of atherosclerosis of the carotid artery requires high resolution imaging of the vessel wall using multiple MR sequences with different contrast weightings. These images allow manual or automated classification of plaque components inside the vessel wall. Automated classification requires all sequences to be in alignment, which is hampered by patient motion. In clinical practice, correction of this motion is performed manually. Previous studies applied automated image registration to correct for motion using only nondeformable transformation models and did not perform a detailed quantitative validation. The purpose of this study is to develop an automated accurate 3D registration method, and to extensively validate this method on a large set of patient data. In addition, the authors quantified patient motion during scanning to investigate the need for correction. Methods: MR imaging studies (1.5T, dedicated carotid surface coil, Philips) from 55 TIA/stroke patients with ipsilateral <70% carotid artery stenosis were randomly selected from a larger cohort. Five MR pulse sequences were acquired around the carotid bifurcation, each containing nine transverse slices: T1-weighted turbo field echo, time of flight, T2-weighted turbo spin-echo, and pre- and postcontrast T1-weighted turbo spin-echo images (T1W TSE). The images were manually segmented by delineating the lumen contour in each vessel wall sequence and were manually aligned by applying throughplane and inplane translations to the images. To find the optimal automatic image registration method, different masks, choice of the fixed image, different types of the mutual information image similarity metric, and transformation models including 3D deformable transformation models, were evaluated. Evaluation of the automatic registration results was performed by comparing the lumen segmentations of the fixed image and

  2. Automated registration of multispectral MR vessel wall images of the carotid artery

    International Nuclear Information System (INIS)

    Purpose: Atherosclerosis is the primary cause of heart disease and stroke. The detailed assessment of atherosclerosis of the carotid artery requires high resolution imaging of the vessel wall using multiple MR sequences with different contrast weightings. These images allow manual or automated classification of plaque components inside the vessel wall. Automated classification requires all sequences to be in alignment, which is hampered by patient motion. In clinical practice, correction of this motion is performed manually. Previous studies applied automated image registration to correct for motion using only nondeformable transformation models and did not perform a detailed quantitative validation. The purpose of this study is to develop an automated accurate 3D registration method, and to extensively validate this method on a large set of patient data. In addition, the authors quantified patient motion during scanning to investigate the need for correction. Methods: MR imaging studies (1.5T, dedicated carotid surface coil, Philips) from 55 TIA/stroke patients with ipsilateral <70% carotid artery stenosis were randomly selected from a larger cohort. Five MR pulse sequences were acquired around the carotid bifurcation, each containing nine transverse slices: T1-weighted turbo field echo, time of flight, T2-weighted turbo spin-echo, and pre- and postcontrast T1-weighted turbo spin-echo images (T1W TSE). The images were manually segmented by delineating the lumen contour in each vessel wall sequence and were manually aligned by applying throughplane and inplane translations to the images. To find the optimal automatic image registration method, different masks, choice of the fixed image, different types of the mutual information image similarity metric, and transformation models including 3D deformable transformation models, were evaluated. Evaluation of the automatic registration results was performed by comparing the lumen segmentations of the fixed image and

  3. Recommendations for protecting against failure by brittle fracture: Category II and III ferritic steel shipping containers with wall thickness greater than four inches

    International Nuclear Information System (INIS)

    This report provides criteria for selecting ferritic steels that would prevent brittle fracture in Category II and III shipping containers with wall thickness greater than 4 inches. These methods are extensions of those previously used for Category II and III containers less than 4 inches thick and Category I containers more than 4 inches thick

  4. Riser Difference Evaluation from Ultrasonic Wall Thickness Inspection of Thirteen Double-Shell Tanks

    Energy Technology Data Exchange (ETDEWEB)

    Weier, Dennis R.; Pardini, Allan F.

    2010-03-15

    PNNL has performed an analysis of ultrasonic thickness measurements taken on Hanford's double-shell tanks (DSTs) approximately eight years apart. The analysis was performed to determine whether significant differences exist between ultrasonic thickness measurements made in two opposite risers in Hanford DSTs that have been examined twice.

  5. Riser Difference Evaluation from Ultrasonic Wall Thickness Inspection of Thirteen Double-Shell Tanks

    International Nuclear Information System (INIS)

    PNNL has performed an analysis of ultrasonic thickness measurements taken on Hanford's double-shell tanks (DSTs) approximately eight years apart. The analysis was performed to determine whether significant differences exist between ultrasonic thickness measurements made in two opposite risers in Hanford DSTs that have been examined twice.

  6. Low-density lipoprotein accumulation within a carotid artery with multilayer elastic porous wall: fluid-structure interaction and non-Newtonian considerations.

    Science.gov (United States)

    Deyranlou, Amin; Niazmand, Hamid; Sadeghi, Mahmood-Reza

    2015-09-18

    Low-density lipoprotein (LDL), which is recognized as bad cholesterol, typically has been regarded as a main cause of atherosclerosis. LDL infiltration across arterial wall and subsequent formation of Ox-LDL could lead to atherogenesis. In the present study, combined effects of non-Newtonian fluid behavior and fluid-structure interaction (FSI) on LDL mass transfer inside an artery and through its multilayer arterial wall are examined numerically. Navier-Stokes equations for the blood flow inside the lumen and modified Darcy's model for the power-law fluid through the porous arterial wall are coupled with the equations of mass transfer to describe LDL distributions in various segments of the artery. In addition, the arterial wall is considered as a heterogeneous permeable elastic medium. Thus, elastodynamics equation is invoked to examine effects of different wall elasticity on LDL distribution in the artery. Findings suggest that non-Newtonian behavior of filtrated plasma within the wall enhances LDL accumulation meaningfully. Moreover, results demonstrate that at high blood pressure and due to the wall elasticity, endothelium pores expand, which cause significant variations on endothelium physiological properties in a way that lead to higher LDL accumulation. Additionally, results describe that under hypertension, by increasing angular strain, endothelial junctions especially at leaky sites expand more dramatic for the high elastic model, which in turn causes higher LDL accumulation across the intima layer and elevates atherogenesis risk. PMID:26300402

  7. Detailed Dynamic Heat Transfer in Thick Brick Walls Typical of Lille Metropolis

    Directory of Open Access Journals (Sweden)

    Antczak E.

    2012-10-01

    Full Text Available The study of thermal transfer in old houses massive walls offers a big interest permitting the understanding of their specificities and the choice of a suitable material for their eventual insulation. We propose to study the thermal transfer in massive brick walls that characterize the Northern Europe old houses. To do so, we will begin by defining the thermal transfer mode: we proved that the transfer mode can be reduced to a unidirectional transfer. Then, an experimental wall is built and submitted to two different solicitation types (constant temperature in steady state mode and sinusoidal temperature through a wooden insulated box containing a radiator. The interest of these solicitations is to determine the thermal properties of the wall: the steady-state regime permits to determine the thermal resistances of the system when the harmonic regime permits to determine the thermal capacities of the system.

  8. Effect of Mould Wall Thickness on Rate of Solidification of Centrifugal Casting

    OpenAIRE

    Madhusudhan; Narendranaath S; S, Mohankumar G C; Mukunda P G

    2010-01-01

    In Centrifugal Casting process the centrifugal force presses the metal against the inner wall of the metal mould, resulting in rapid solidification of the molten metal. However the solidification structures like structural uniformity and structural character of the solidified metal of centrifugal casting is of great importance, regarding to its mechanical properties. The solidification time of the casting is dependent upon the various parameters like speed ofrotation of the mold, mould wall t...

  9. Mechanical Interaction of an Expanding Coiled Stent with a Plaque-Containing Arterial Wall: A Finite Element Analysis.

    Science.gov (United States)

    Welch, Tré R; Eberhart, Robert C; Banerjee, Subhash; Chuong, Cheng-Jen

    2016-03-01

    Wall injury is observed during stent expansion within atherosclerotic arteries, related in part to stimulation of the inflammatory process. Wall stress and strain induced by stent expansion can be closely examined by finite element analysis (FEA), thus shedding light on procedure-induced sources of inflammation. The purpose of this work was to use FEA to examine the interaction of a coiled polymer stent with a plaque-containing arterial wall during stent expansion. An asymmetric fibrotic plaque-containing arterial wall model was created from intravascular ultrasound (IVUS) images of a diseased artery. A 3D model for a coil stent at unexpanded state was generated in SolidWorks. They were imported into ANSYS for FEA of combined stent expansion and fibrotic plaque-distortion. We simulated the stent expansion in the plaqued lumen by increasing balloon pressure from 0 to 12 atm in 1 atm step. At increasing pressure, we examined how the expanding stent exerts forces on the fibrotic plaque and vascular wall components, and how the latter collectively resist and balance the expansive forces from the stent. Results show the expanding coiled stent creates high stresses within the plaque and the surrounding fibrotic capsule. Lower stresses were observed in adjacent medial and adventitial layers. High principal strains were observed in plaque and fibrotic capsule. The results suggest fibrotic capsule rupture might occur at localized regions. The FEA/IVUS method can be adapted for routine examination of the effects of the expansion of selected furled stents against IVUS-reconstructed diseased vessels, to improve stent deployment practices. PMID:26621671

  10. Carotid thin fluttering bands: A new element of arterial wall remodelling? An ultrasound study.

    Science.gov (United States)

    Costanzo, Luca; Sole, Andrea; Tamburino, Corrado; Di Pino, Luigi

    2015-10-01

    Carotid artery ultrasound is a non-invasive and reproducible technique used for early atherosclerotic assessment. Intimal flap has been described in the presence of dissection or mobile plaque rupture, however presence of carotid thin fluttering bands (TFBs) have not been described yet. To investigate frequency, characteristics and impact of TFBs in carotid lumen of patients who underwent carotid ultrasound scan (CUS). 3341 patients were admitted from January 2009 to January 2014. Patients with history of cerebral ischemia (CI) were excluded. In the cases in which TFBs were observed, a 3-months clinical and CUS follow-up (FU) was performed. TFBs were found in 71 patients (2.1%). The mean age was 63.41 ± 11.20 years (range 42-89). All patients showed a mean increase in intima-media thickness. We identified two subgroups: in 22 patients the TFB was related to a carotid plaque while in 49 no carotid plaque was found. TFB mostly originated in the carotid bulb (88.7%) and was similarly located in carotid arteries (49.3% left-side and 50.7% right-side). CUS and clinical FU were available for all patients (mean duration 25.34 months, median 19). CI occurred in none of the patients. TFB disappeared in 13 patients (18.3%) with no sign or symptoms of CI. In 3 of 49 patients without carotid plaque (6.1%), progressive thickening beneath TFB was observed. TFB is a rare finding. Longer FU is needed to evaluate its prognosis. To date, the pathophysiology is unknown, however it could be related to vascular remodeling. PMID:26179862

  11. Filled and empty states of carbon nanotubes in water: Dependence on nanotube diameter, wall thickness and dispersion interactions

    Indian Academy of Sciences (India)

    Malay Rana; Amalendu Chandra

    2007-09-01

    We have carried out a series of molecular dynamics simulations of water containing a narrow carbon nanotube as a solute to investigate the filling and emptying of the nanotube and also the modifications of the density and hydrogen bond distributions of water inside and also in the vicinity of the outer surfaces of the nanotube. Our primary goal is to look at the effects of varying nanotube diameter, wall thickness and also solute-solvent interactions on the solvent structure in the confined region also near the outer surfaces of the solute. The thickness of the walls is varied by considering single and multi-walled nanotubes and the interaction potential is varied by tuning the attractive strength of the 12-6 pair interaction potential between a carbon atom of the nanotubes and a water molecule. The calculations are done for many different values of the tuning parameter ranging from fully Lennard-Jones to pure repulsive pair interactions. It is found that both the solvation characteristics and hydrogen bond distributions can depend rather strongly on the strength of the attractive part of the solute-water interaction potential. The thickness of the nanotube wall, however, is found to have only minor effects on the density profiles, hydrogen bond network and the wetting characteristics. This indicates that the long range electrostatic interactions between water molecules inside and on the outer side of the nanotube do not make any significant contribution to the overall solvation structure of these hydrophobic solutes. The solvation characteristics are primarily determined by the balance between the loss of energy due to hydrogen bond network disruption, cavity repulsion potential and offset of the same by attractive component of the solute-water interactions. Our studies with different system sizes show that the essential features of wetting and dewetting characteristics of narrow nanotubes for different diameter and interaction potentials are also present in

  12. Carotid artery intima media thickness as a surrogate marker of atherosclerosis in patient with chronic renal failure on hemodialysis

    Directory of Open Access Journals (Sweden)

    Jayanta Paul

    2012-01-01

    Full Text Available Background: In patients with chronic renal failure (CRF, carotid artery intima media thickness (CAIMT is increased when the patients are on hemodialysis. Vascular events caused by atherosclerosis are the major cause of death in patients undergoing hemodialysis. Aims: This study was done to find out the relationship between carotid artery intima media thickness and hemodialysis in chronic renal failure patients independent of classical risk factors and also the relationship between CAIMT of hemodialyzed patients and nonhemodialyzed CRF patients. Materials and Methods: In this observational study, CAIMT of 78 CRF patients was examined by B-mode ultrasonography. Glomerular filtration rate (GFR was calculated by using the "Modification of Diet in Renal Disease" formula. CRF patients, who had been on regular hemodialysis treatment (treated thrice weekly for at least 6 months, were identified as hemodialyzed patients. Data were analyzed by software Statistical package for the social Sciences (SPSS (17 th version. Results: There was significant positive correlation between CAIMT and hemodialysis (P=0.045 independent of traditional risk factors. Hemodialyzed patients had higher mean CAIMT (1136.30±21.21 μm, P<0.001 than mean CAIMT of age and sex matched nondialyzed patients (959.30±23.01 μm. Conclusion: Hemodialysis is an independent risk factor for atherosclerosis in CRF patents. Hemodialyzed patients have significantly higher CAIMT than nondialyzed CRF patients.

  13. A Computer-Aided Diagnosis System for Measuring Carotid Artery Intima-Media Thickness (IMT) Using Quaternion Vectors.

    Science.gov (United States)

    Kutbay, Uğurhan; Hardalaç, Fırat; Akbulut, Mehmet; Akaslan, Ünsal; Serhatlıoğlu, Selami

    2016-06-01

    This study aims investigating adjustable distant fuzzy c-means segmentation on carotid Doppler images, as well as quaternion-based convolution filters and saliency mapping procedures. We developed imaging software that will simplify the measurement of carotid artery intima-media thickness (IMT) on saliency mapping images. Additionally, specialists evaluated the present images and compared them with saliency mapping images. In the present research, we conducted imaging studies of 25 carotid Doppler images obtained by the Department of Cardiology at Fırat University. After implementing fuzzy c-means segmentation and quaternion-based convolution on all Doppler images, we obtained a model that can be analyzed easily by the doctors using a bottom-up saliency model. These methods were applied to 25 carotid Doppler images and then interpreted by specialists. In the present study, we used color-filtering methods to obtain carotid color images. Saliency mapping was performed on the obtained images, and the carotid artery IMT was detected and interpreted on the obtained images from both methods and the raw images are shown in Results. Also these results were investigated by using Mean Square Error (MSE) for the raw IMT images and the method which gives the best performance is the Quaternion Based Saliency Mapping (QBSM). 0,0014 and 0,000191 mm(2) MSEs were obtained for artery lumen diameters and plaque diameters in carotid arteries respectively. We found that computer-based image processing methods used on carotid Doppler could aid doctors' in their decision-making process. We developed software that could ease the process of measuring carotid IMT for cardiologists and help them to evaluate their findings. PMID:27137786

  14. Pharmacogenomics of estrogens on changes in carotid artery intima-medial thickness and coronary arterial calcification: Kronos Early Estrogen Prevention Study.

    Science.gov (United States)

    Miller, Virginia M; Jenkins, Gregory D; Biernacka, Joanna M; Heit, John A; Huggins, Gordon S; Hodis, Howard N; Budoff, Matthew J; Lobo, Rogerio A; Taylor, Hugh S; Manson, JoAnn E; Black, Dennis M; Naftolin, Frederick; Harman, S Mitchell; de Andrade, Mariza

    2016-01-01

    Prior to the initiation of menopausal hormone treatment (MHT), genetic variations in the innate immunity pathway were found to be associated with carotid artery intima-medial thickness (CIMT) and coronary arterial calcification (CAC) in women (n = 606) enrolled in the Kronos Early Estrogen Prevention Study (KEEPS). Whether MHT might affect these associations is unknown. The association of treatment outcomes with variation in the same 764 candidate genes was evaluated in the same KEEPS participants 4 yr after randomization to either oral conjugated equine estrogens (0.45 mg/day), transdermal 17β-estradiol (50 μg/day), each with progesterone (200 mg/day) for 12 days each month, or placebo pills and patch. Twenty SNPs within the innate immunity pathway most related with CIMT after 4 yr were not among those associated with CIMT prior to MHT. In 403 women who completed the study in their assigned treatment group, single nucleotide polymorphisms (SNPs) within the innate immunity pathway were found to alter the treatment effect on 4 yr change in CIMT (i.e., significant interaction between treatment and genetic variation in the innate immunity pathway; P 5 Agatston units after 4 yr. Results of this study suggest that hormonal status may interact with genetic variants to influence cardiovascular phenotypes, specifically, the pharmacogenomic effects within the innate immunity pathway for CIMT. PMID:26508701

  15. Measure Guideline. Incorporating Thick Layers of Exterior Rigid Insulation on Walls

    Energy Technology Data Exchange (ETDEWEB)

    Lstiburek, Joseph [Building Science Corporation, Westford, MA (United States); Baker, Peter [Building Science Corporation, Westford, MA (United States)

    2015-04-09

    This measure guideline, written by the U.S. Department of Energy’s Building America team Building Science Corporation, provides information about the design and construction of wall assemblies that use layers of rigid exterior insulation thicker than 1-½ in. and that require a secondary cladding attachment location exterior to the insulation. The guideline is separated into several distinct sections that cover: (1) fundamental building science principles relating to the use of exterior insulation on wall assemblies; (2) design principles for tailoring this use to the specific project goals and requirements; and (3) construction detailing to increase understanding about implementing the various design elements.

  16. Measure Guideline: Incorporating Thick Layers of Exterior Rigid Insulation on Walls

    Energy Technology Data Exchange (ETDEWEB)

    Lstiburek, Joseph [Building Science Corporation, Westford, MA (United States); Baker, Peter [Building Science Corporation, Westford, MA (United States)

    2015-04-01

    This measure guideline provides information about the design and construction of wall assemblies that use layers of rigid exterior insulation thicker than 1-½ inches and that require a secondary cladding attachment location exterior to the insulation. The guideline is separated into several distinct sections that cover: fundamental building science principles relating to the use of exterior insulation on wall assemblies; design principles for tailoring this use to the specific project goals and requirements; and construction detailing to increase understanding about implementing the various design elements.

  17. LIFE CYCLE ASSESSMENT OF A HEMP CONCRETE WALL: IMPACT OF THICKNESS AND COATING.

    OpenAIRE

    Prétot, Sylvie; Collet, Florence; Garnier, Charles

    2014-01-01

    In a context of sustainable development and energy sparing, a life cycle assessment (LCA) may be useful to make good choices. Thus, this study concerns the LCA of an environmentally friendly material used for building construction, hemp concrete. The functional unit is first defined per square such that the wall may provide the function of bearing wall meter and its thermal performance is described by a thermal resistance of 2.78 m².K/W. The results then showed that the production phase of ra...

  18. Diagnostic accuracy of myocardial deformation indices for detecting high risk coronary artery disease in patients without regional wall motion abnormality

    OpenAIRE

    Rostamzadeh, Alireza; Shojaeifard, Maryam; Rezaei, Yousef; Dehghan, Kasra

    2015-01-01

    Background: The prediction of coronary artery disease (CAD) by conventional echocardiographic measurements is principally based on the estimation of ejection fraction and regional wall motion abnormality (RWMA). This study aimed to determine whether strain echocardiography of left ventricle measured by velocity vector imaging (VVI) method could detect patients with a high-risk CAD. Methods: In a prospective study, a total of 119 consecutive patients who were assessed for eligibility were cate...

  19. Characterizaton of the Vessel Geometry, Flow Mechanics and Wall Shear Stress in the Great Arteries of Wildtype Prenatal Mouse

    OpenAIRE

    Choon Hwai Yap; Xiaoqin Liu; Kerem Pekkan

    2014-01-01

    Characterizaton of the Vessel Geometry, Flow Mechanics and Wall Shear Stress in the Great Arteries of Wildtype Prenatal Mouse Choon Hwai Yap1, Xiaoqin Liu2, Kerem Pekkan3* 1 Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore, 2 Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America, 3 Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh...

  20. Characterization of the vessel geometry, flow mechanics and wall shear stress in the great arteries of wildtype prenetal mouse

    OpenAIRE

    Pekkan, Kerem; Yap, C.H.; Liu, X.

    2014-01-01

    Characterizaton of the Vessel Geometry, Flow Mechanics and Wall Shear Stress in the Great Arteries of Wildtype Prenatal Mouse Choon Hwai Yap1, Xiaoqin Liu2, Kerem Pekkan3* 1 Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore, 2 Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America, 3 Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh...

  1. Ultrasonic testing of thick-walled components, comparison of performance LLT/tandem

    International Nuclear Information System (INIS)

    To prove the suitability of LLT (longitudinal transverse wave) test technique as a replacement for conventional tandem technique, investigations were carried out on test specimens and on a reactor pressure vessel wall. The LLT technique was especially tested as to how far it is able to replace conventional tandem testing. (orig./MM)

  2. Measurement of the 3D arterial wall strain tensor using intravascular B-mode ultrasound images: a feasibility study

    Science.gov (United States)

    Liang, Yun; Zhu, Hui; Friedman, Morton H.

    2010-11-01

    Intravascular ultrasound (IVUS) elastography is a promising tool for studying atherosclerotic plaque composition and assessing plaque vulnerability. Current IVUS elastography techniques can measure the 1D or 2D strain of the vessel wall using various motion tracking algorithms. Since biological soft tissue tends to deform non-uniformly in 3D, measurement of the complete 3D strain tensor is desirable for more rigorous analysis of arterial wall mechanics. In this paper, we extend our previously developed method of 2D arterial wall strain measurement based on non-rigid image registration into 3D strain measurement. The new technique registers two image volumes acquired from the same vessel segment under different levels of luminal pressure and longitudinal stress. The 3D displacement field obtained from the image registration is used to calculate the local 3D strain tensor. From the 3D strain tensor, radial, circumferential and longitudinal strain distributions can be obtained and displayed. This strain tensor measurement method is validated and evaluated using IVUS images of healthy porcine carotid arteries subjected to a luminal pressure increase and longitudinal stretch. The ability of the algorithm to overcome systematic noise was tested, as well as the consistency of the results under different longitudinal frame resolutions.

  3. Rate of solidification of aluminium casting in varying wall thickness of cylindrical metallic moulds

    Directory of Open Access Journals (Sweden)

    Katsina Christopher BALA

    2014-02-01

    Full Text Available The quality of final casting mainly depends on the rate of solidification as rapid solidification produces fine grains structures with better mechanical properties. The analysis of heat transfer during the casting and solidification of aluminium alloy as well as the experimental investigation of the rate of solidification in varying thicknesses of cylindrical metallic mould was carried out. The temperature variation with time of the casting was recorded from which cooling curves were obtained for the determination of solidification time of the cast. The results showed that as the cylindrical mould thickness increases the solidification time decreases due to the chilling effect of the mould.

  4. Continuous monitoring of the wall thickness of pipelines with ultrasonic waves; Dauerueberwachung der Wanddicke von Rohrleitungen mit Ultraschall

    Energy Technology Data Exchange (ETDEWEB)

    Mueck, Andreas [SONOTEC Ultraschallsensorik Halle GmbH, Halle (Saale) (Germany); Imhof, Dietmar [TUeV NORD MPA GmbH und Co.KG, Leuna (Germany)

    2015-07-01

    Pipelines in industrial plants must be constantly monitored due to occurring erosion and corrosion. The determination of the residual wall thickness is generally carried out with ultrasound. Often, the critical points are difficult to access and the pipes insulated. The preparation and evaluation of a measurement is therefore very costly. The measuring system SONOWALL S ultrasonic probes are firmly attached to the pipeline and installed into isolation. The number and position of the probes can be freely selected. Often, the load is not known exactly why the monitoring of the pipe wall thickness over the entire circumference is necessary. The acoustic coupling to the pipe is done with proven adhesives that do not lose their adhesive strength even under changing ambient temperatures. The connecting cables are housed away up to 20 m in an easily accessible place in a terminal box. There can be done a wall thickness measurement with conventional ultrasonic testing devices. By using standardized components, the measuring system meets the requirements of DIN EN 12668 and DIN EN 14127. [German] Rohrleitungen in industriellen Anlagen muessen aufgrund der auftretenden Erosion und Korrosion permanent ueberwacht werden. Die Bestimmung der Restwanddicke erfolgt in der Regel mit Ultraschall. Oftmals sind die kritischen Stellen schwer zugaenglich und die Rohrleitungen isoliert. Die Vor- und Nachbereitung einer Messung ist dadurch sehr aufwendig. Beim Messsystem SONOWALL S werden Ultraschallpruefkoepfe fest an der Rohrleitung angebracht und in die Isolation eingebaut. Die Anzahl und Position der Pruefkoepfe ist dabei frei waehlbar. Oft ist die Belastung nicht genau bekannt, weshalb eine Ueberwachung der Rohrwanddicke ueber den gesamten Umfang notwendig ist. Die akustische Ankopplung an das Rohr erfolgt mit erprobten Klebstoffen, die auch bei wechselnden Umgebungstemperaturen ihre Haftfestigkeit nicht verlieren. Die Anschlusskabel werden bis zu 20m entfernt an einer gut

  5. Residual stress distribution measurement in welded thick-walled pipe joints using inherent strain method. Comparison in different groove geometries

    International Nuclear Information System (INIS)

    The inherent strain method measures weld residual stress by coupling of approach to measure inherent strain which is source of residual stress in weld structures with elastic computation to estimate residual stress from inherent strain. In this study, the weld residual stress distributions in the welded thick-walled pipe joints of stainless steel were measured using the inherent strain method. The different features between residual stress distribution in the two kinds of joint with the standard and narrow groove geometries were clarified using the contour map of the whole joints estimated by the method. (author)

  6. Modelling the solidification of ductile cast iron parts with varying wall thicknesses

    DEFF Research Database (Denmark)

    Bjerre, Mathias Karsten; Tiedje, Niels Skat; Thorborg, Jesper;

    2015-01-01

    a 2D FE solution of the heat conduction equation is developed in an in-house code and model parameters are calibrated using experimental data from representative castings made of ductile cast iron. The main focus is on the influence of casting thickness and resulting local cooling conditions on the...

  7. The importance of ultrasonographic measurement of peritoneal wall thickness in pediatric chronic peritoneal dialysis patients.

    Science.gov (United States)

    Yavaşcan, Önder; Aksu, Nejat; Alparslan, Caner; Sarıtaş, Serdar; Elmas, Cengiz Han; Eraslan, Ali Nihat; Duman, Soner; Mir, Sevgi

    2015-04-01

    Loss of peritoneal function due to peritoneal fibrosing syndrome (PFS) is a major factor leading to treatment failure in chronic peritoneal dialysis (PD) patients. Although the precise biologic mechanisms responsible for these changes have not been defined, the general assumption is that alterations in peritoneal function are related to structural changes in the peritoneal membrane. Studies of the peritoneal membrane by non-invasive ultrasonography (US) in chronic PD patients are limited. The aim of the present study is to assess the relationship between functional parameters of peritoneum and peritoneal thickness measured by US in children treated by chronic PD. We recruited two groups of patients: 23 subjects (13 females, 10 males) on chronic PD (patient group) and 26 (7 females, 19 males) on predialysis out-patient follow-up (creatinine clearance: 20-60 mL/min/1.73 m(2)) (control group). Age, sex, weight, height, body mass index (BMI), chronic PD duration, episodes of peritonitis and the results of peritoneal equilibration test (PET) were recorded. Hemoglobin (Hb), blood pressure (BP), left ventricular mass index (LVMI) and renal osteodystrophy (ROD) parameters were also obtained. The thickness of the parietal peritoneum was measured by trans-abdominal US in all children. Statistical analyses were performed by using Student's t and Pearson's correlation tests. Mean peritoneal thickness in chronic PD patients (1028.26 ± 157.26 μm) was significantly higher than control patients (786.52 ± 132.33). Mean peritoneal thickness was significantly correlated with mean body height (R(2) = 0.93, p measurement of peritoneal membrane thickness is a simple and non-invasive method in chronic PD children. This diagnostic tool likely enables to assess peritoneal structure and function in these patients. PMID:25594613

  8. Investigations for deducing wall thickness of aluminium shell casting using three dimensional printing

    Directory of Open Access Journals (Sweden)

    R. Singh

    2008-12-01

    Full Text Available Purpose: of the present study is to verify the feasibility of decreasing the shell thickness in rapid shell castingbased upon ‘three dimensional printing’ technology in order to evaluate the dimensional accuracy for aluminumcastings. Rapid prototyping has been in evidence for the past twenty years and is being widely used in diverseareas, from the building of aesthetic and functional prototypes to the production of tools and moulds fortechnological prototypesDesign/methodology/approach: Further consistency with the tolerance grades of the castings has been checkedas per IT grades along with mechanical properties of the aluminium castings. Starting from the identification ofcomponent/ 87benchmark, technological prototypes are produced with different shell thicknesses. Measurementson a coordinate measuring machine allowed calculating the dimensional tolerances of the castings produced.Findings: The research proved that the shell thickness having value less than the recommended one is moresuitable from dimensional accuracy and economic point of view. The result indicates that at 5 mm shellthickness, hardness of the casting is improved by 3.79%. Further production cost and production time has beenreduced by 54.6% and 55.4% respectively in comparison to 12 mm recommended shell thickness.Practical implications: The analysis procedure is better for proof of concept and for the new product, for whichthe cost of production for dies and other tooling is more.Originality/value: The 3DP technique at different shell thicknesses (12 mm to 2 mm provided satisfactoryresults, limited at present to the field of light alloys. This process ensures rapid production of pre-seriestechnological prototypes and proof of concept at less production cost and time.

  9. Wall thickness of the carotid artey as an indicator of generalized atherosclerosis : the Rotterdam study

    OpenAIRE

    Bots, Michiel

    1993-01-01

    textabstractThe past decades have led to a better understanding of the etiology and pathogenesis of atherosclerosis and its clinical sequelae. Several risk factors have been identified that promote atherosclerosis to develop and of which it is currently known that their presence increases the risk of cardiovascular disease. At present, cardiovascular disease is believed to be caused by an interplay of advanced atherosclerotic vessel wall changes, stenosis and thrombosis. However, the question...

  10. Cardiovascular risk in chronic kidney disease patients: intima-media thickness predicts the incidence and severity of histologically assessed medial calcification in radial arteries

    OpenAIRE

    Janda, Katarzyna; Krzanowski, Marcin; Gajda, Mariusz; Dumnicka, Paulina; Fedak, Danuta; Grzegorz J. Lis; Jaśkowski, Piotr; Pietrzycka, Agata; Jan A. Litwin; Sułowicz, Władysław

    2015-01-01

    Background The objective of the study was to determine the relationship between common carotid artery intima-media thickness (CCA-IMT) and histologically assessed calcification of radial artery in relation to clinical features and laboratory markers of bone and mineral metabolism, inflammation, and oxidative stress in patients with stage 5 chronic kidney disease (CKD). Methods The study comprised 59 patients (36 hemodialyzed, 23 predialysis). CCA-IMT was measured by ultrasonography; the bioch...

  11. A new non-invasive ultrasonic method for simultaneous measurements of longitudinal and radial arterial wall movements: first in vivo trial.

    OpenAIRE

    Persson, Magnus; Rydén Ahlgren, Åsa; Jansson, Tomas; Eriksson, Anders; Persson, Hans W; Lindström, Kjell

    2003-01-01

    During recent years, the radial movement of the arterial wall has been extensively studied, and measurements of the radial movement are now an important tool in cardiovascular research for characterizing the mechanical properties of the arterial wall. In contrast, the longitudinal movement of vessels has gained little or no attention as it has been presumed that this movement is negligible. With modern high-resolution ultrasound, it can, however, be seen that the intima-media complex of the a...

  12. Nuclear microprobe investigation into the trace elemental contents of carotid artery walls of apolipoprotein E deficient mice

    International Nuclear Information System (INIS)

    Atherosclerosis is a progressive disease that causes lesions in large and medium-sized arteries. There is increasing evidence that the function of vascular endothelial cells is impaired by oxidation reactions, and that metal ions may participate in these processes. The nuclear microscopy facility in NUS, which has the ability to focus a 2 MeV proton beam down to sub micron spot sizes, was used to investigate the trace elemental changes (e.g. Zn and Fe) in atherosclerotic lesions in the common carotid artery of apolipoprotein E deficient mice fed a high fat diet. In this preliminary study, which is part of a larger study to investigate the effects of probucol on carotid artery atherosclerosis, two sets of mice were used; a test set fed a high fat diet +1% probucol, and a control set which was fed a high fat diet only. The results show that the Zn/Fe ratio was significantly higher in the media of arteries of probucol treated animals without overlying lesion (4.3) compared to the media with overlying lesion (1.3) (p = 0.004) for test mice. For the control mice, the arterial Zn/Fe ratio was 1.8 for media without overlying lesion, compared with 1.0 for media with overlying lesion (p = 0.1). Thus, for media without overlying lesion, the Zn/Fe ratio was significantly higher (p = 0.009) in probucol-treated (4.3) than control mice (1.8), whereas there was little difference in the ratios between the two groups in media with overlying lesion (1.3 compared with 1.0). These preliminary results are consistent with the idea that the levels of iron and zinc concentrations within the artery wall may influence the formation of atherosclerotic plaque in the carotid artery

  13. Evaluation of Carotid Arterial Intima-Media Thickness (IMT and Its Relation to Clinical Parameters in Japanese Children

    Directory of Open Access Journals (Sweden)

    Tamura,Hiroko

    2011-02-01

    Full Text Available The aim of this study was to evaluate the carotid arterial intima-media thickness (IMT and its relation to clinical parameters in Japanese children. Fifty-two healthy children (39 boys and 13 girls, aged 6-14 years, were enrolled in this cross-sectional investigation study. IMT of the common carotid artery was determined using ultrasonography. We also investigated anthropometric parameters, blood pressure (BP, lifestyles and blood examinations. The mean value of IMT was 0.4±0.1mm, which was lower than the normal value (1.0mm in adults. IMT was positively correlated with age (r=0.340 and height (r=0.346 in boys, while it was positively correlated with body mass index (BMI (r=0.584 and diastolic BP (DBP (r=0.563 in girls. In addition, IMT was associated with sleeping hours and hours of watching television (TV by using stepwise regression analysis. In conclusion, IMT increased with aging, and it was linked to some clinical parameters of atherosclerosis and lifestyles in children. Therefore, this reference data will be helpful for future assessment of age-related change in Japanese children in clinical practice, and IMT might be a good predictor of atherosclerosis in Japanese children.

  14. Automatic detection of the intima-media thickness in ultrasound images of the common carotid artery using neural networks.

    Science.gov (United States)

    Menchón-Lara, Rosa-María; Bastida-Jumilla, María-Consuelo; Morales-Sánchez, Juan; Sancho-Gómez, José-Luis

    2014-02-01

    Atherosclerosis is the leading underlying pathologic process that results in cardiovascular diseases, which represents the main cause of death and disability in the world. The atherosclerotic process is a complex degenerative condition mainly affecting the medium- and large-size arteries, which begins in childhood and may remain unnoticed during decades. The intima-media thickness (IMT) of the common carotid artery (CCA) has emerged as one of the most powerful tool for the evaluation of preclinical atherosclerosis. IMT is measured by means of B-mode ultrasound images, which is a non-invasive and relatively low-cost technique. This paper proposes an effective image segmentation method for the IMT measurement in an automatic way. With this purpose, segmentation is posed as a pattern recognition problem, and a combination of artificial neural networks has been trained to solve this task. In particular, multi-layer perceptrons trained under the scaled conjugate gradient algorithm have been used. The suggested approach is tested on a set of 60 longitudinal ultrasound images of the CCA by comparing the automatic segmentation with four manual tracings. Moreover, the intra- and inter-observer errors have also been assessed. Despite of the simplicity of our approach, several quantitative statistical evaluations have shown its accuracy and robustness. PMID:24281725

  15. Thick growing multilayer nanobrick wall thin films: super gas barrier with very few layers.

    Science.gov (United States)

    Guin, Tyler; Krecker, Michelle; Hagen, David Austin; Grunlan, Jaime C

    2014-06-24

    Recent work with multilayer nanocoatings composed of polyelectrolytes and clay has demonstrated the ability to prepare super gas barrier layers from water that rival inorganic CVD-based films (e.g., SiOx). In an effort to reduce the number of layers required to achieve a very low oxygen transmission rate (OTR (layer-by-layer (LbL) assembly. Buffering the chitosan solution and its rinse with 50 mM Trizma base increased the thickness of these films by an order of magnitude. The OTR of a 1.6-μm-thick, six-bilayer film was 0.009 cc/m(2)·day·atm, making this the best gas barrier reported for such a small number of layers. This simple modification to the LbL process could likely be applied more universally to produce films with the desired properties much more quickly. PMID:24914613

  16. Coating of a stainless steel tube-wall catalytic reactor with thermally treated polysiloxane thick films

    OpenAIRE

    Guillou, L.; Supiot, P.; Le Courtois, V.

    2005-01-01

    Organosilicon films were grafted over stainless steel substrates thanks to a plasma assisted chemical vapor deposition process. Thicknesses up to 10μm were developed. The organosilicon films were then thermally treated under air and the influence of calcinations conditions was investigated by infrared spectroscopy, Raman microscopy and XPS. On all films, it appears that the structure varies according to the thermal treatment parameters. Indeed the surface composition appears to be SiO1.8 whic...

  17. Measuring the thickness of austenitic weld deposits on carbon steel walls using a magnetic method

    International Nuclear Information System (INIS)

    The theoretical background is described of a magnetic method characterized by a marked compensation of the undesirable effect of δ-ferrite content in the deposit, on the accuracy of measuring deposit thickness. A description is also given of the basic types of sensors and the results are summarized of comparing measurements performed on weld deposits of WWER-type reactor pressure vessels. (author). 7 figs., 5 refs

  18. [Determinants of vascular wall stiffness in patients with chronic renal disease undergoing hemodialysis].

    Science.gov (United States)

    Kharlamova, U V; Il'icheva, O E

    2012-01-01

    Examination of 109 patients with chronic renal disease undergoing hemodialysis revealed significant impairment of arterial wall distensibility (accordingly, decreased Peterson's and Young's elastic moduli, distensibility coefficient). The relative thickness of the common carotid artery and pulse wave velocity were significantly greater than in practically healthy subjects. Independent factors influencing arterial wall rigidity included age, arterial pressure, total cholesterol and homocystein, stable metabolites of nitric oxide, creatinine, calcium, phosphorus levels, calcium x phosphorus product, duration of hemodialysis, interdialytic weight gain. PMID:23516853

  19. Hemodynamic analysis in an idealized artery tree: differences in wall shear stress between Newtonian and non-Newtonian blood models.

    Directory of Open Access Journals (Sweden)

    Jared C Weddell

    Full Text Available Development of many conditions and disorders, such as atherosclerosis and stroke, are dependent upon hemodynamic forces. To accurately predict and prevent these conditions and disorders hemodynamic forces must be properly mapped. Here we compare a shear-rate dependent fluid (SDF constitutive model, based on the works by Yasuda et al in 1981, against a Newtonian model of blood. We verify our stabilized finite element numerical method with the benchmark lid-driven cavity flow problem. Numerical simulations show that the Newtonian model gives similar velocity profiles in the 2-dimensional cavity given different height and width dimensions, given the same Reynolds number. Conversely, the SDF model gave dissimilar velocity profiles, differing from the Newtonian velocity profiles by up to 25% in velocity magnitudes. This difference can affect estimation in platelet distribution within blood vessels or magnetic nanoparticle delivery. Wall shear stress (WSS is an important quantity involved in vascular remodeling through integrin and adhesion molecule mechanotransduction. The SDF model gave a 7.3-fold greater WSS than the Newtonian model at the top of the 3-dimensional cavity. The SDF model gave a 37.7-fold greater WSS than the Newtonian model at artery walls located immediately after bifurcations in the idealized femoral artery tree. The pressure drop across arteries reveals arterial sections highly resistive to flow which correlates with stenosis formation. Numerical simulations give the pressure drop across the idealized femoral artery tree with the SDF model which is approximately 2.3-fold higher than with the Newtonian model. In atherosclerotic lesion models, the SDF model gives over 1 Pa higher WSS than the Newtonian model, a difference correlated with over twice as many adherent monocytes to endothelial cells from the Newtonian model compared to the SDF model.

  20. Hemodynamic analysis in an idealized artery tree: differences in wall shear stress between Newtonian and non-Newtonian blood models.

    Science.gov (United States)

    Weddell, Jared C; Kwack, JaeHyuk; Imoukhuede, P I; Masud, Arif

    2015-01-01

    Development of many conditions and disorders, such as atherosclerosis and stroke, are dependent upon hemodynamic forces. To accurately predict and prevent these conditions and disorders hemodynamic forces must be properly mapped. Here we compare a shear-rate dependent fluid (SDF) constitutive model, based on the works by Yasuda et al in 1981, against a Newtonian model of blood. We verify our stabilized finite element numerical method with the benchmark lid-driven cavity flow problem. Numerical simulations show that the Newtonian model gives similar velocity profiles in the 2-dimensional cavity given different height and width dimensions, given the same Reynolds number. Conversely, the SDF model gave dissimilar velocity profiles, differing from the Newtonian velocity profiles by up to 25% in velocity magnitudes. This difference can affect estimation in platelet distribution within blood vessels or magnetic nanoparticle delivery. Wall shear stress (WSS) is an important quantity involved in vascular remodeling through integrin and adhesion molecule mechanotransduction. The SDF model gave a 7.3-fold greater WSS than the Newtonian model at the top of the 3-dimensional cavity. The SDF model gave a 37.7-fold greater WSS than the Newtonian model at artery walls located immediately after bifurcations in the idealized femoral artery tree. The pressure drop across arteries reveals arterial sections highly resistive to flow which correlates with stenosis formation. Numerical simulations give the pressure drop across the idealized femoral artery tree with the SDF model which is approximately 2.3-fold higher than with the Newtonian model. In atherosclerotic lesion models, the SDF model gives over 1 Pa higher WSS than the Newtonian model, a difference correlated with over twice as many adherent monocytes to endothelial cells from the Newtonian model compared to the SDF model. PMID:25897758

  1. Analytical Solution for Interference Fit for Multi-Layer Thick-Walled Cylinders and the Application in Crankshaft Bearing Design

    Directory of Open Access Journals (Sweden)

    Jun Qiu

    2016-06-01

    Full Text Available Interference fit is an important contact mode used for torque transmission existing widely in engineering design. To prevent trackslip, a certain magnitude of interference has to be ensured; meanwhile, the interference needs to be controlled to avoid failure of the mechanical components caused by high assembly stress. The finite element method (FEM can be used to analyze the stress, while the computational cost of FEM involving nonlinear contact algorithm is relatively high, and likely to come across low precision and convergence problems. Therefore, a rapid and accurate analytical method for estimation is of vital need, especially for the initial design stage when the parameters vary in a large range. In this study, an analytical method to calculate the contact pressure and stress between multi-layer thick-walled cylinders (MLTWC with multi-contact pairs and temperature-raising effect is proposed, and evaluated by FEM. The analytical solution of the interference for tri-layer thick-walled cylinders is applied to the design of engine crankshaft bearing. The results indicate that the analytical method presented in this study can reduce complexity of MLTWC problems and improve the computational efficiency. It is well suited to be used for the calculation model of parameter optimization in early design.

  2. FRAM isotopic analysis of uranium in thick-walled containers using high energy gamma rays and planar HPGe detectors.

    Energy Technology Data Exchange (ETDEWEB)

    Sampson, Thomas E.; Hypes, P. A. (Philip A.); Vo, Duc T.

    2002-01-01

    We describe the use of the Los Alamos FRAM isotopic analysis software to make the first reported measurements on thick-walled UF{sub 6} cylinders using small planar HPGe detectors of the type in common use at the IAEA. Heretofore, planar detector isotopic analysis measurements on uranium have used the 100-keV region and can be defeated by 10 mm of steel absorber. The analysis of planar detector measurements through 13-16 mm of steel shows that FRAM can successfully carry out these measurements and analysis in the 120-1024 keV energy range, a range previously thought to be the sole province of more efficient coaxial detectors. This paper describes the measurement conditions and results and also compares the results to other FRAM measurements with coaxial HPGe detectors. The technique of gamma-ray isotopic analysis of arbitrary samples is desirable for measuring the isotopic composition of uranium in UF{sub 6} cylinders because it does not require calibration with standards or knowledge of the cylinder wall thickness. The International Atomic Energy Agency (IAEA) uses the MGAU (Multi Group Analysis Uranium) uranium isotopic analysis software with planar high purity germanium (HPGe) detectors to measure the isotopic composition of uranium. Measurements on UF{sub 6} cylinders with 13-16-mm thick steel walls are usually unsuccessful because of the strong absorption of the 89-100 keV gamma rays and x-rays that MGAU requires for the measurement. This paper describes the use of the Los Alamos FRAM isotopic analysis software to make these measurements on UF{sub 6} cylinders. Uranium measurements with FRAM typically cover the energy range from 120-1001 keV and can easily be made through the walls of UF{sub 6} cylinders. While these measurements are usually performed with efficient coaxial HPGe detectors, this paper reports the first successful measurements using small planar HPGe detectors of the type in common use at the IAEA.

  3. Comparison of carotid artery intima - media thickness and risk factors of atherosclerosis in lacunar versus non-lacunar cerebral infarcts

    Directory of Open Access Journals (Sweden)

    Seyed Ali Mousavi

    2007-07-01

    Full Text Available

    BACKGROUND: Increases in the thickness of the intima-media of the carotid artery have been associated with an increased risk of myocardial infarction and stroke in subjects without a history of cardiovascular disease. Lacunar infarcts, one of the most common subtypes of ischemic stroke, show unique pathological and clinicoradiological characteristics. The present study examined the relationship between the vascular risk factors, including carotid artery intimamedia thickness (IMT, and lacunar versus non-lacunar infarcts.
    METHODS: We collected data from patients admitted to hospital with acute ischemic stroke. 195 Patients and 96 control subjects underwent B-mode ultrasonographic measurements of IMT of the common carotid artery. We examined the association of lacunar and non-lacunar infarcts with age, sex, and potential vascular risk factors.
    RESULTS: Of 195 adult patients with acute ischemic stroke, 87 were considered lacunar and 108 were considered nonlacunar strokes. Between these two groups of patients, we did not find a significantly different percentage of diabetes,
    smoking, hypertension, dyslipidemia, myocardial infarction, or previous history of ischemic stroke, alcohol, obesity,
    atherogen diet, exercise, and IMT. However, patients with lacunar infarct, diabetes mellitus (P = 0.02, and hypertension
    (P = 0.02 had a significantly higher percentage of history of prior CVA (P = 0.03 and a significantly higher percentage
    of non-lacunar infarct.
    CONCLUSIONS: The present results indicated that diabetes mellitus and hypertension are more common in patients with lacunar infarcts, and history of CVA is more common in patients with non–lacunar infarcts. We further concluded that IMT cannot differentiate subtypes of ischemic stroke. Because risk factors and clinical presentation of ischemic stroke differ among races, more national studies

  4. Analytical solution for the pseudoelastic response of a shape memory alloy thick-walled cylinder under internal pressure

    International Nuclear Information System (INIS)

    Analytical solutions are derived for the isothermal pseudoelastic response of a shape memory alloy (SMA) thick-walled cylinder subjected to internal pressure. The Tresca transformation criterion and linear hardening are used. Equations are given for the radial and circumferential stresses, transformation strains and radial displacement at various steps of loading and unloading. A structural pressure–temperature phase diagram is provided for the cylinder, analogous to the stress–temperature phase diagram of SMA materials. Pressurization of an initially 100% austenitic cylinder causes the martensite to initially form at the inner radius. For a relatively thin-walled cylinder the transformation front reaches the outer radius before the transformation has completed at the inner radius, whereas for a thick-walled cylinder the transformation completes at the inner radius while there is still an outer ring of 100% austenite. For a given OD/ID ratio, a critical temperature is derived that stipulates which of these two cases occurs. An analytical result is provided for the pressure that will cause the transformation to complete at the inner radius. During unloading, the reverse transformation can start at either the inner or the outer surface of the cylinder and can propagate outward and then reverse its direction and propagate back to the inner surface. The effect of martensitic transformation on the structural yield strength due to plasticity is also investigated and it is shown that the pressure required to initiate yielding can be substantially decreased or increased depending on the temperature and the state of transformation achieved, even though the yield stress of the material is independent of temperature. Finally, the effectiveness of the Tresca transformation criterion to derive closed-form solutions for this problem is demonstrated by comparing with finite element solutions using the von Mises theory. (paper)

  5. The influence of anatomic variance in the coronary artery on cardiac function with PCI after acute inferior wall myocardial infarction

    International Nuclear Information System (INIS)

    Objective: To analyze the influence in anatomic variance of coronary artery on function of left and right ventricles after acute inferior myocardial infarction (AIMI) treated with percutaneous coronary intervention therapy (PCI). Methods: Forty-seven inferior AIMI patients were divided into 2 groups: 12 left dominant group [including equipollent case, i.e. inferior wall of left ventricle supplied by left circumflex coronary artery (LCX), right ventricle by right coronary artery (RCA)] and 35 right dominant group (both inferior wall and right ventricle were supplied by RCA). Equilibrium radionuclide angiocardiography (ERNA) and myocardial perfusion imaging (MPI) were used for comparing the influence between different coronary artery flow patterns on biventricular hemodynamics, blood supply and prognosis of PCI after 3 months. Results: Comparison of ventricular function in left and right dominant coronal artery type groups discharged 7- 10 d after PCI, there were differences in left ventricular ejection fraction (LVEF) [(63.03 ± 5.64)% vs (57.67 ± 7.35)%, P=0.012], peak ejection rate (PER) [(3.52 ± 0.66) end-diastolic volume (EDV)/s vs (2.93 ± 0.73) EDV/s, P =0.011], peak filling rate (PFR) [(2.71 ± 0.88) EDV/s vs (2.11 ± 0.45 ) EDV/s, P=0.004], left free-wall regional ejection fraction [(81.94 ± 20.75)% vs (67.25 ± 16.54)%, P = O.032], and right free-wall regional ejection fraction [(57.86 ± 11.77)% vs (67.83 ± 10.38)%, P=0.012], right ventricular ejection fraction (RVEF) [(37.89 ± 3.86)% vs (41.67 ± 4.81)%, P=0.09]. After 3 months,there was difference only in RVEF [(44.60 ± 5.29)% vs (48.00 ± 3.30)%, P=0.043], but no difference in myocardial perfusion of left ventricle (P=0.357). Conclusions: In acute stage of AIMI right dominant group, there was more severe injury of right ventricle, in convalescent stage most of the right ventricular function resumed. The sustained right ventricular function in part of the patients can be demonstrated by ERNA

  6. Arterial wall rigidity in active and standard therapy of patients with chronic heart failure (three-year investigation

    Directory of Open Access Journals (Sweden)

    Rebrov A.P.

    2012-03-01

    Full Text Available Aim: to evaluate arterial wall rigidity, clinical condition and prognosis in active and standard therapy of patients with chronic heart failure (CHF. Materials and methods. A total of 211 patients with CHF experienced Q-wave myocardial infarction was enrolled in the study. At admission to the hospital all patients were randomized into two groups. Patients of the first group (n=106 were managed actively after discharge from the hospital, patients of the second group (n=105 were managed conventionally after discharge from the hospital. Patients were observed for three years. Re-sults. Over three year-investigation actively managed patients demonstrated significant (p<0,05 decrease in systolic and diastolic blood pressure, heart rate, blood serum levels of total cholesterol, N-terminal cerebral natriuretic peptide, increase of 6-minute walk-test, left ventricle ejection fraction reduction and decrease in number hospitalization of patients with CHF as compared to those who were conventionally managed. At patients of II group pulse wave speed in aorta (PWVA since the first year, an index of augmentation of brachial artery and systolic pressure in aorta in three years of supervision above (p<0,05 in comparison with patients of group I. Conclusion. One of deterioration factors of systolic functions of the left ventricle and the prognosis in patients with CHF of group of standard therapy was progressing of arterial wall rigidity pathology

  7. Impaired Arterial Elasticity Identified by Pulse Waveform Analysis as a Marker for Vascular Wall Damage in Humans With Aging and Hypertension

    Institute of Scientific and Technical Information of China (English)

    Wang Yan; Tao Jun; Tu Chang; Yang Zhen; Xu Mingguo; Wang Jiemei; Jin Yafei; Ma Hong

    2005-01-01

    Objectives Cardiovascular risk factors lead to pathogenesis of atherosclerosis and its clinical events by impairing vascular wall. Endothelial dysfunction is the earliest marker for vascular wall injuries. Development of new method to detect early vascular wall damage has an important clinical implication for the prevention and treatment of cardiovascular diseases. Therefore, the present study was performed to evaluate effect of aging and hypertension, two independent risk factors for cardiovascular diseases, on arterial elasticity by using pulse waveform analysis and investigate whether the changes in arterial elasticity can be used as a risk marker for vascular structural and functional abnormalities. Methods Using modified Windkessel model of the circulation and pulse waveform analysis,C 1 large artery and C2 small artery elasticity indices of 204 Chinese normal healthy subjects ( age 15-80years) and 46 Chinese essential hypertensive patients (age 35-70 years) were measured. Age- and hypertension-related arterial elasticity changes were examined. Results C1 large artery and C2 small artery elasticity indices were reduced with advancing age in healthy subjects. C1 large artery and C2 small artery elasticity indices were negatively correlated with age (r=-0.628, P<0.001; r=-0.595, P<0.001). C1 large artery and C2 small artery elasticity indices in patients with essential hypertension compared with the agematched healthy subjects were (9.31±3.85 ml/mm Hg x 10 versus 15.13±4.14 ml/mmHg x 10, P<0.001) and (3.57± 1.62 ml/mm Hg x 100 versus 7.89±2.91 ml/mmHg ×100 P <0.001), respectively, and were significantly lower than the corresponding healthy subjects. There were negative association between C1large artery and C2 small artery elasticity indices and systolic blood pressure (r=-0.37, P<0.05; r=-0.39,P<0.05) and pulse pressure (r=-0.39, P<0.05; r=0.43,P<0.05) in patients with essential hypertension.Conclusions Advancing age and essential

  8. SU-C-BRA-04: Use of Esophageal Wall Thickness in Evaluation of the Response to Chemoradiation Therapy for Esophageal Cancer

    International Nuclear Information System (INIS)

    Purpose: To quantitatively evaluate the esophageal cancer response to chemoradiation therapy (CRT) by measuring the esophageal wall thickness in CT. Method: Two datasets were used in this study. The first dataset is composed of CT scans of 15 esophageal cancer patients and 15 normal controls. The second dataset is composed of 20 esophageal cancer patients who underwent PET/CT scans before (Pre-CRT) and after CRT (Post-CRT). We first segmented the esophagus using a multi-atlas-based algorithm. The esophageal wall thickness was then computed, on each slice, as the equivalent circle radius of the segmented esophagus excluding the lumen. To evaluate the changes of wall thickness, we computed the standard deviation (SD), coefficient of variation (COV, SD/Mean), and flatness [(Max–Min)/Mean] of wall thickness along the entire esophagus. Results: For the first dataset, the mean wall thickness of cancer patients and normal controls were 6.35 mm and 6.03 mm, respectively. The mean SD, COV, and flatness of the wall thickness were 2.59, 0.21, and 1.27 for the cancer patients and 1.99, 0.16, and 1.13 for normal controls. Statistically significant differences (p < 0.05) were identified in SD and flatness. For the second dataset, the mean wall thickness of pre-CRT and post-CRT patients was 7.13 mm and 6.84 mm, respectively. The mean SD, COV, and flatness were 1.81, 0.26, and 1.06 for pre-CRT and 1.69, 0.26, and 1.06 for post-CRT. Statistically significant difference was not identified for these measurements. Current results are based on the entire esophagus. We believe significant differences between pre- and post-CRT scans could be obtained, if we conduct the measurements at tumor sites. Conclusion: Results show thicker wall thickness in pre-CRT scans and differences in wall thickness changes between normal and abnormal esophagus. This demonstrated the potential of esophageal wall thickness as a marker in the tumor CRT response evaluation. This work was supported in part by

  9. Association of depression with common carotid artery intima media thickness and augmentation index in a large Urban South Indian population- The Chennai Urban Rural Epidemiology Study (CURES - 138)

    OpenAIRE

    Subramani Poongothai; Rajendra Pradeepa; Karunakaran Indulekha; Jayagopi Surendar; Viswanathan Mohan

    2015-01-01

    AIM: The aim of the study was to assess the relationship of depression with carotid intima media thickness and augmentation index in Asian Indians. Research Design and Methods : For this study, 1505 subjects were randomly selected from a population based study conducted in Chennai, South India. Right common carotid artery intima medial thickness [IMT] was determined using high-resolution B-mode ultrasonography. Augmentation index [AI] was measured using the Sphygmocor apparatus. Depressive sy...

  10. Do the cardiovascular risk profile and the degree of arterial wall calcification influence the performance of MDCT angiography of lower extremity arteries?

    International Nuclear Information System (INIS)

    To retrospectively assess the influence of arterial wall calcifications on the accuracy of run-off computed tomographic angiography (CTA) and to analyse whether cardiovascular risk factors are predictors of compromising calcifications. In 200 consecutive patients who underwent run-off CTA, calcifications were assessed in pelvic, thigh and calf arteries using a four-point scale. Fifty-nine patients with digital subtraction angiography (DSA) were assessed by both techniques to estimate a threshold of compromising calcifications, defined as a decrease of sensitivity, specificity, PPV or NPV below the lower 95% confidence interval of overall results. Regression analysis was performed to investigate a potential relationship between compromising calcifications and presence of cardiovascular risk factors, advanced patient age and severe peripheral arterial disease (PAD). The highest Ca++-score was chosen as the cut-off for the regression analysis, as a relevant decrease of specificity (0.91; overall: 0.95) above the knee and of sensitivity (0.66; overall: 0.83), specificity (0.65; overall: 0.93), positive predictive value (PPV) and negative predictive value (NPV) below the knee was observed. In the pelvic and thigh arteries, severe PAD (Fontaine Stage ≥III) showed the highest odds ratio for compromising calcifications (2.9), followed by diabetes mellitus (2.4), renal failure (2.1) and smoking (1.7). In the calf, renal failure (12.2) and diabetes mellitus (3.3) were the strongest predictors. Patients with diabetes and renal failure should be considered as candidates for alternative vessel imaging in order to avoid inconclusive examination results. (orig.)

  11. Do the cardiovascular risk profile and the degree of arterial wall calcification influence the performance of MDCT angiography of lower extremity arteries?

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, B.C.; Werncke, T.; Foert, E.; Ribbe, C.; Wolf, K.J. [Charite-University Medicine, Department of Radiology and Nuclear Medicine, Berlin (Germany); Kruschewski, M. [Charite-University Medicine, Department of Surgery, Berlin (Germany); Hopfenmueller, W. [Charite-University Medicine, Department of Biometry and Clinical Epidemiology, Berlin (Germany); Albrecht, T. [Charite-University Medicine, Department of Radiology and Nuclear Medicine, Berlin (Germany); Vivantes Klinikum Neukoelln, Department of Radiology and Interventional Therapy, Berlin (Germany)

    2010-02-15

    To retrospectively assess the influence of arterial wall calcifications on the accuracy of run-off computed tomographic angiography (CTA) and to analyse whether cardiovascular risk factors are predictors of compromising calcifications. In 200 consecutive patients who underwent run-off CTA, calcifications were assessed in pelvic, thigh and calf arteries using a four-point scale. Fifty-nine patients with digital subtraction angiography (DSA) were assessed by both techniques to estimate a threshold of compromising calcifications, defined as a decrease of sensitivity, specificity, PPV or NPV below the lower 95% confidence interval of overall results. Regression analysis was performed to investigate a potential relationship between compromising calcifications and presence of cardiovascular risk factors, advanced patient age and severe peripheral arterial disease (PAD). The highest Ca{sup ++}-score was chosen as the cut-off for the regression analysis, as a relevant decrease of specificity (0.91; overall: 0.95) above the knee and of sensitivity (0.66; overall: 0.83), specificity (0.65; overall: 0.93), positive predictive value (PPV) and negative predictive value (NPV) below the knee was observed. In the pelvic and thigh arteries, severe PAD (Fontaine Stage {>=}III) showed the highest odds ratio for compromising calcifications (2.9), followed by diabetes mellitus (2.4), renal failure (2.1) and smoking (1.7). In the calf, renal failure (12.2) and diabetes mellitus (3.3) were the strongest predictors. Patients with diabetes and renal failure should be considered as candidates for alternative vessel imaging in order to avoid inconclusive examination results. (orig.)

  12. Algisyl-LVR™ with coronary artery bypass grafting reduces left ventricular wall stress and improves function in the failing human heart

    OpenAIRE

    Lee, LC; Wall, ST; Klepach, D; Ge, L; Zhang, Z.; Lee, RJ; Hinson, A; Gorman, JH; Gorman, RC; Guccione, JM

    2013-01-01

    Background Left ventricular (LV) wall stress reduction is a cornerstone in treating heart failure. Large animal models and computer simulations indicate that adding non-contractile material to the damaged LV wall can potentially reduce myofiber stress. We sought to quantify the effects of a novel implantable hydrogel (Algisyl-LVR™) treatment in combination with coronary artery bypass grafting (i.e. Algisyl-LVR™ + CABG) on both LV function and wall stress in heart failure patients. Methods and...

  13. Arterial bending angle and wall morphology correlate with slow coronary flow: Determination with multidetector CT coronary angiography

    International Nuclear Information System (INIS)

    Background and purpose: The purpose of this study was to assess angulations and vessel wall morphology that could lead to bending head loss in the RCA and LMCA arteries of patients with slow coronary flow (SCF) evaluated by MDCT coronary angiography. Methods: The study involved 51 patients (45 males, mean age: 59.6 years) who were diagnosed with SCF by coronary angiography. Diagnosis of SCF was based on thrombolysis in myocardial infarction (TIMI) frame count. Fifty-one patients with absence of slow flow were selected as the control group. The angulations of the main coronary arteries with the aorta were measured from the axial images obtained through MDCT coronary angiography, and the findings were recorded. In addition, the coronary artery walls of these patients were evaluated. For statistical analysis, SPSS for Windows 10.0 (SPSS Inc., Chicago, IL) was used. For comparisons of the angles, either independent samples t test or the Mann-Whitney U test was used where appropriate. Results: The results of the study indicated that 38 patients had SCF in the LAD. Comparisons of patients with SCF with the controls revealed that in the patients with SCF, the mean angle of the LMCA with the aorta (40.9 ± 20.5o) was statistically significantly smaller than the mean angle of the LMCA with the aorta in the control cases (71.8 ± 11o). In 12 patients, slow flow was detected in the RCA. Those with slow flow in the RCA had significantly smaller angles (mean: 33.2 ± 20.4o) than the other cases (mean: 78.9 ± 10.7o). Conclusion: A small angle of origin of the main coronary arteries from the aorta, measured on MDCT examinations is correlated with slow blood flow in those vessels, as calculated by the TIMI frame count in catheter coronary angiography.

  14. A theory for water and macromolecular transport in the pulmonary artery wall with a detailed comparison to the aorta.

    Science.gov (United States)

    Zeng, Zhongqing; Jan, Kung-Ming; Rumschitzki, David S

    2012-04-15

    The pulmonary artery (PA) wall, which has much higher hydraulic conductivity and albumin void space and approximately one-sixth the normal transmural pressure of systemic arteries (e.g, aorta, carotid arteries), is rarely atherosclerotic, except under pulmonary hypertension. This study constructs a detailed, two-dimensional, wall-structure-based filtration and macromolecular transport model for the PA to investigate differences in prelesion transport processes between the disease-susceptible aorta and the relatively resistant PA. The PA and aorta models are similar in wall structure, but very different in parameter values, many of which have been measured (and therefore modified) since the original aorta model of Huang et al. (23). Both PA and aortic model simulations fit experimental data on transwall LDL concentration profiles and on the growth of isolated endothelial (horseradish peroxidase) tracer spots with circulation time very well. They reveal that lipid entering the aorta attains a much higher intima than media concentration but distributes better between these regions in the PA than aorta and that tracer in both regions contributes to observed tracer spots. Solutions show why both the overall transmural water flow and spot growth rates are similar in these vessels despite very different material transport parameters. Since early lipid accumulation occurs in the subendothelial intima and since (matrix binding) reaction kinetics depend on reactant concentrations, the lower intima lipid concentrations in the PA vs. aorta likely lead to slower accumulation of bound lipid in the PA. These findings may be relevant to understanding the different atherosusceptibilities of these vessels. PMID:22198178

  15. EMAT Technology for a Wall Thickness Measurement of an Oxide Scaled Carbon Steel Piping

    International Nuclear Information System (INIS)

    EMAT(Electro-Magnetic Acoustic Transducer) uses a combination of static and dynamic magnetic fields to convert electrical energy into acoustic energy. The static magnetic field is induced by permanent magnet and the dynamic magnetic field is produced by the electrical coil. There are two contributions from an EMAT transducer that generate an ultrasonic signal. The first contribution is the Lorentz Force which is the most commonly utilized contribution within the NDT industry. The second contribution from an EMAT transducer utilizes the magnetostrictive force, which is less well-known. The sample that will be examined within this paper involves the presence of a high temperature oxide scale that is commonly found on the external walls of boiler tubes. The high temperatures, in excess of 500 .deg. C or 1000 .deg. F, can cause the steam and flue gas constituents to react with steel to form a brittle iron oxide called magnetite on the inside and outside surfaces of a steel boiler tubing. The magnetostrictive EMAT can produce ultrasonic signals under a specific condition, such as, the presence of magnetic conductive materials. Hence, the objective of this study is to investigate the feasibility of a magnetostrictive EMAT for an effective inspection of material loss for a nuclear power piping system

  16. Environmentally-controlled fracture of an overstrained A723 steel thick-walled cylinder

    Science.gov (United States)

    Underwood, J. H.; Olmstead, V. J.; Askew, J. C.; Kapusta, A. A.; Young, G. A.

    1992-08-01

    A through-wall, 1.7 m long crack grew suddenly from a notch in a 285 mm outer diameter (OD) of an A723 steel overstrained tube that was undergoing plating operations with no externally applied loads. The fracture mechanics tests and analyses and the fractography performed to characterize the cracking are described. The tube had a yield strength of 1200 MPa, fracture toughness of 150 MPavm, and a tensile residual stress at the OD of about 600 MPa. The composition was typical of an air-melt A723 steel, and the electropolishing bath, consisting of sulfuric and phosphoric acids, was held at 54 C. The bolt-loaded test for the threshold stress intensity factor for environmentally controlled cracking described by Wei and Novak was used here with two significant modifications. Some tests included only a notch with the radius matching that of the tube, and a new expression for K in terms of crack-mouth displacement was developed and used. Scanning electron microscope fractography and energy dispersive x ray spectra were used to identify crack mechanisms. Results of the study include: (1) a measured threshold of hydrogen stress cracking for the material/environment below 20 MPavm; (2) da/dt versus K behavior typical of classic environmental control; and (3) an improved K/v expression for the bolt-loaded specimen and associated criteria for determining plane-strain test conditions in relation to the Irwin plastic zone.

  17. Atherosclerosis and rheumatoid arthritis: relationships between intima-media thickness of the common carotid arteries and disease activity and disabilty

    Directory of Open Access Journals (Sweden)

    G. La Montagna

    2011-09-01

    Full Text Available Objectives. To investigate the intima-media thickness of the common carotid arteries (IMT-CCA in patients with Rheumatoid Arthritis (RA, and its relationships with classical atherosclerosis risk factors and disease features i.e. duration, activity and disability. Methods. 48 RA patients (35 F, 13 M; age ed 26-69 years median 55; disease duration 1-18 years, median 8, and 22 controls (16 F, 6 M; age 28-66, median 50 matched for classical atherosclerosis risk factors, i.e. age, sex, smoking, blood pressure, body mass index, diabetes, familiarity, and for postemopausal status, were studied. IMT and plaques were measured in the left and right common carotid arteries. Serum total cholesterol, trygliceridies, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, apoliprotein AI, apolipoprotein B, and rheumatoid factor were determined in patients and controls. The DAS28, the HAQ-DI and disease duration were considered as clinical parameters reflecting disease status. Results. The IMT-CCA (mean ± SD was significantly greater in the 48 RA patients than in the 22 controls subjects (1.00±0.25 vs. 0.78±0.21; p=0.0007. In the 70 subjects investigated CCA-IMT resulted to be significantly correlated with diastolic blood pressure, body mass index, triglycerides and RA status. In the 48 RA patients no correlation was detected with either disease duration or activity or disability. Conclusion: our study confirms an increased IMT in RA patients without any clinically evident manifestation of cardiovascular disease. It supports the existence of subclinical atherosclerosis in RA.

  18. Deformable templates for plaque thickness estimation of intravascular ultrasound sequences

    OpenAIRE

    Escolano Ruiz, Francisco; Cazorla Quevedo, Miguel Ángel; Gallardo López, Domingo; Rizo Aldeguer, Ramón

    1997-01-01

    Deformable Template models are first applied to estimate the wall of coronary arteries in intravascular ultrasound sequences. Two circular templates (inner and outer) are used to localize and track an image zone that contains the atheroma plaque. Moreover robust wall thickness estimations are derived from this analysis.

  19. Ability of combined Near-Infrared Spectroscopy-Intravascular Ultrasound (NIRS-IVUS) imaging to detect lipid core plaques and estimate cap thickness in human autopsy coronary arteries

    Science.gov (United States)

    Grainger, S. J.; Su, J. L.; Greiner, C. A.; Saybolt, M. D.; Wilensky, R. L.; Raichlen, J. S.; Madden, S. P.; Muller, J. E.

    2016-03-01

    The ability to determine plaque cap thickness during catheterization is thought to be of clinical importance for plaque vulnerability assessment. While methods to compositionally assess cap integrity are in development, a method utilizing currently available tools to measure cap thickness is highly desirable. NIRS-IVUS is a commercially available dual imaging method in current clinical use that may provide cap thickness information to the skilled reader; however, this is as yet unproven. Ten autopsy hearts (n=15 arterial segments) were scanned with the multimodality NIRS-IVUS catheter (TVC Imaging System, Infraredx, Inc.) to identify lipid core plaques (LCPs). Skilled readers made predictions of cap thickness over regions of chemogram LCP, using NIRS-IVUS. Artery segments were perfusion fixed and cut into 2 mm serial blocks. Thin sections stained with Movat's pentachrome were analyzed for cap thickness at LCP regions. Block level predictions were compared to histology, as classified by a blinded pathologist. Within 15 arterial segments, 117 chemogram blocks were found by NIRS to contain LCP. Utilizing NIRSIVUS, chemogram blocks were divided into 4 categories: thin capped fibroatheromas (TCFA), thick capped fibroatheromas (ThCFA), pathological intimal thickening (PIT)/lipid pool (no defined cap), and calcified/unable to determine cap thickness. Sensitivities/specificities for thin cap fibroatheromas, thick cap fibroatheromas, and PIT/lipid pools were 0.54/0.99, 0.68/0.88, and 0.80/0.97, respectively. The overall accuracy rate was 70.1% (including 22 blocks unable to predict, p = 0.075). In the absence of calcium, NIRS-IVUS imaging provided predictions of cap thickness over LCP with moderate accuracy. The ability of this multimodality imaging method to identify vulnerable coronary plaques requires further assessment in both larger autopsy studies, and clinical studies in patients undergoing NIRS-IVUS imaging.

  20. Method of heating weld zone of thick-walled large-diameter cylindrical parts and equipment therefor

    International Nuclear Information System (INIS)

    The object of the new method of heating the weld zone of thick-walled large-diameter cylindrical parts is to remove time and energy losses and to secure that the parts are welded without interrupting the heating. The production process consists in the heating of the weld zone of the first and second rings to welding temperature, then the two are welded together. The welding area is kept at the specified temperature. Prior to the termination of the welding the preheating is begun of the welding zone of the following pair of rings. The same process takes place in the welding of other rings. The equipment consists of a mobile undercarriage on which are placed mobile induction heaters. (J.B.). 2 figs

  1. Numerical Simulation of Transient 3-D Turbulent Heated Jet into Crossflow in a Thick-Wall T-Junction Pipe

    Institute of Scientific and Technical Information of China (English)

    Wu Hailing; Chen Tingkuan; Luo Yushan; Wang Haijun

    2001-01-01

    The present work is to investigate the transient three-dimensional heated turbulent jet into crossflow in a thick wall T-junction pipe using CFD package. Two cases with the jet-to-crossflow velocity ratio of 0.05 and 0.5 are computed, with a finite-volume method utilizing k-ε turbulent model. Comparison of the steady-state computations with measured data shows good qualitative agreement. Transient process of injection is simulated to examine the thermal shock on the T-junction component. Temporal temperature of the component is acquired by thermal coupling with the fluid. Via analysis of the flow and thermal characteristics, factors causing the thermal shock are studied. Optimal flow rates are discussed to reduce the thermal shock.

  2. Optimization of instruments for the neutron control of thickness of the metal walls of filled vessels and pipes

    International Nuclear Information System (INIS)

    The article deals with the theoretical and experimental results of the complex optimization of instruments for the nondestructive radiation control of the wall thickness of metallic vessels and pipes. The authors used the systems approach aiming at increasing the sensitivity of control by optimization according to the multidimensional vector of structural elements and operating regimes of the instrument: the spatial and energy-angular distribution of the radiation source; the energy range of registration of radiation; and the type, geometric disposition, and dimensions of the detector. With the object of checking the reliability of the results of mathematical modeling, they obtained experimental data for separate points. Reflected neutrons were registered by detectors SNM-16 based on 3He and DNM-29B based on 10B, gamma quanta of radiative capture of thermal neutrons on iron were registered spectrometrically be detector based on NaI(Tl)

  3. Fracture behavior of shallow cracks in full-thickness clad beams from an RPV wall section

    International Nuclear Information System (INIS)

    A testing program is described that utilizes full-thickness clad beam specimens to quantify fracture toughness for shallow cracks in weld material for which metallurgical conditions are prototypic of those found in reactor pressure vessels (RPVs). The beam specimens are fabricated from an RPV shell segment that includes weld, plate and clad material. Metallurgical factors potentially influencing fracture toughness for shallow cracks in the beam specimens include material gradients and material inhomogeneities in welded regions. The shallow-crack clad beam specimens showed a significant loss of constraint similar to that of other shallow-crack single-edge notch bend (SENB) specimens. The stress-based Dodds-Anderson scaling model appears to be effective in adjusting the test data to account for in-plane loss of constraint for uniaxially tested beams, but cannot predict the observed effects of out-of-plane biaxial loading on shallow-crack fracture toughness. A strain-based dual-parameter fracture toughness correlation (based on plastic zone width) performed acceptably when applied to the uniaxial and biaxial shallow-crack fracture toughness data

  4. Examination of Cell Shape in Wall Thickness Direction for Foamed Polyurethane Resin

    Science.gov (United States)

    Kono, Tsutomu; Matsuoka, Shin-Ichi; Araki, Kuninari; Iseki, Takashi

    The foaming flow process of polyurethane resin is difficult because temperature, density and thermal conductivity are changed greatly by heat generation resulting from the mixing reaction of polyol and polyisocyanate resin. It is thought that thermal conductivity and strength are influenced by cell shape after the foaming process. In this study, we evaluate three-dimensional cell shapes by quantitatively observation of the ratio of the diameter of the parallel and the perpendicular section to flow direction, the ratio of the major axis and the minor axis, and direction of the major axis of cells for closed cell shapes in foamed polyurethane resin. It is thought that cell shapes are mainly deformed by shear stress and pressure of adjacent cells. It becomes obvious by cell shape evaluation that cells in the skin layer are compressed in the thickness direction by pressure of adjacent cells, cells between the skin layer and the core layer are stretched perpendicular to the flow direction by shear stress, and cells in the core layer are similar to the sphere shape.

  5. Adenosine concentration in the porcine coronary artery wall and A2A receptor involvement in hypoxia-induced vasodilatation

    Science.gov (United States)

    Frøbert, Ole; Haink, Gesine; Simonsen, Ulf; Gravholt, Claus H; Levin, Max; Deussen, Andreas

    2006-01-01

    We tested whether hypoxia-induced coronary artery dilatation could be mediated by an increase in adenosine concentration within the coronary artery wall or by an increase in adenosine sensitivity. Porcine left anterior descendent coronary arteries, precontracted with prostaglandin F2α (10−5m), were mounted in a pressure myograph and microdialysis catheters were inserted into the tunica media. Dialysate adenosine concentrations were analysed by HPLC. Glucose, lactate and pyruvate were measured by an automated spectrophotometric kinetic enzymatic analyser. The exchange fraction of [14C]adenosine over the microdialysis membrane increased from 0.32 ± 0.02 to 0.46 ± 0.02 (n = 4, P < 0.01) during the study period. At baseline, interstitial adenosine was in the region of 10 nm which is significantly less than previously found myocardial concentrations. Hypoxia (PO2 30 mmHg for 60 min, n = 5) increased coronary diameters by 20.0 ± 2.6% (versus continuous oxygenation −3.1 ± 2.4%, n = 6, P < 0.001) but interstitial adenosine concentration fell. Blockade of adenosine deaminase (with erythro-9-(2-hydroxy-3-nonyl-)-adenine, 5 μm), adenosine kinase (with iodotubericidine, 10 μm) and adenosine transport (with n-nitrobenzylthioinosine, 1 μm) increased interstitial adenosine but the increase was unrelated to hypoxia or diameter. A coronary dilatation similar to that during hypoxia could be obtained with 30 μm of adenosine in the organ bath and the resulting interstitial adenosine concentrations (n = 5) were 20 times higher than the adenosine concentration measured during hypoxia. Adenosine concentration–response experiments showed vasodilatation to be more pronounced during hypoxia (n = 9) than during normoxia (n = 9, P < 0.001) and the A2A receptor antagonist ZM241385 (20 nm, n = 5), attenuated hypoxia-induced vasodilatation while the selective A2B receptor antagonist MRS1754 (20 nm, n = 4), had no effect. The lactate/pyruvate ratio was significantly increased in

  6. Optimized aspect ratios of restrained thick-wall cylinders by virtue of Poisson's ratio selection. Part two: Temperature application

    International Nuclear Information System (INIS)

    Highlights: → Incontrovertible evidence is presented that thermal stresses in cylindrical components which include nuclear reactors and containment vessels are shown to be highly dependent on the Poisson's ratio of the materials. → The key novelty is concerned with the identification of a new potential thermal applications for negative Poisson's ratio (auxetic) materials; i.e. those that get fatter when they are stretched. → Negative Poisson's ratio (auxetic) materials exhibit lower thermal stress build-up than conventional positive Poisson's ratio materials, this conjecture being proven using thermal surface plots. - Abstract: Analytical and numerical modelling have been employed to show that the choice of Poisson's ratio is one of the principal design criteria in order to reduce thermal stress build-up in isotropic materials. The modelling procedures are all twofold; consisting of a solution to a steady-state heat conduction problem followed by a linear static solution. The models developed take the form of simplistic thick-wall cylinders such model systems are applicable at macro-structural and micro-structural levels as the underlining formulations are based on the classical theory of elasticity. Generally, the results show that the Poisson's ratio of the material has a greater effect on the magnitude of the principal stresses than the aspect ratio of the cylinders investigated. Constraining the outside of these models significantly increases the thermal stresses induced. The most significant and original finding presented is that the for both freely expanding and constrained thick-wall cylinders the optimum Poisson's ratio is minus unity.

  7. Fluid–structure interaction analysis of bioprosthetic heart valves: Significance of arterial wall deformation

    OpenAIRE

    Hsu, Ming-Chen; Kamensky, David; Bazilevs, Yuri; Sacks, Michael S; Hughes, Thomas J. R.

    2014-01-01

    We propose a framework that combines variational immersed-boundary and arbitrary Lagrangian–Eulerian (ALE) methods for fluid–structure interaction (FSI) simulation of a bioprosthetic heart valve implanted in an artery that is allowed to deform in the model. We find that the variational immersed-boundary method for FSI remains robust and effective for heart valve analysis when the background fluid mesh undergoes deformations corresponding to the expansion and contraction of the elastic artery....

  8. The effect of wall mechanical properties on patency of arterial grafts.

    OpenAIRE

    Kidson, I. G.

    1983-01-01

    Normal arteries have properties which match the low output impedance of the heart to the high peripheral impedance. These properties can be assessed in terms of compliance (% diameter change per unit pressure change) as well as by other haemodynamic parameters. Experiments were designed using vein, Dacron and expanded polytetrafluoroethylene (PTFE) in a low flow canine femoral artery bypass model. No graft group achieved perfect patency. At twelve weeks 80% of vein grafts, 30% of Dacron graft...

  9. AdaBoost classification for model-based segmentation of the outer wall of the common carotid artery in CTA

    Science.gov (United States)

    Vukadinovic, D.; van Walsum, T.; Manniesing, R.; van der Lugt, A.; de Weert, T. T.; Niessen, W. J.

    2008-03-01

    A novel 2D slice based fully automatic method for model based segmentation of the outer vessel wall of the common carotid artery in CTA data set is introduced. The method utilizes a lumen segmentation and AdaBoost, a fast and robust machine learning algorithm, to initially classify (mark) regions outside and inside the vessel wall using the distance from the lumen and intensity profiles sampled radially from the gravity center of the lumen. A similar method using the distance from the lumen and the image intensity as features is used to classify calcium regions. Subsequently, an ellipse shaped deformable model is fitted to the classification result. The method achieves smaller detection error than the inter observer variability, and the method is robust against variation of the training data sets.

  10. Examination of nanoparticles as a drug carrier on blood flow through catheterized composite stenosed artery with permeable walls.

    Science.gov (United States)

    Ijaz, S; Nadeem, S

    2016-09-01

    In this paper, we have discussed the influence of copper nanoparticles on a blood flow through composite stenosed artery with permeable walls. The nature of blood is discussed mathematically by considering it as viscous nanofluid. The study is carried out for a blood vessel under mild stenosis approximations and expressions of the temperature, velocity, resistance impedance to flow, wall shear stress and the pressure gradient is obtained by using corresponding boundary conditions. Results for the effects of permeability on blood flow through composite stenosis have been discussed graphically. The considered analysis also summarizes that the drug copper nanoparticles are efficient to reduce hemodynamics of stenosis and could be helpful to predict important uses for biomedical applications. Results indicate that nanoparticles are helpful as drug carriers to minimize the effects of resistance impedance to blood flow or coagulation factors due to stenosis. PMID:27393802

  11. Uncertainty induced by chest wall thickness assessment methods on lung activity estimation for plutonium and americium: a large population-based study

    International Nuclear Information System (INIS)

    In vivo lung counting aims at assessing the retained activity in the lungs. The calibration factor relating the measured counts to the worker’s specific retained lung activity can be obtained by several means and strongly depends on the chest wall thickness. Here we compare, for 374 male nuclear workers, the activity assessed with a reference protocol, where the material equivalent chest wall thickness is known from ultrasound measurements, with two other protocols. The counting system is an array of four germanium detectors. It is found that non site-specific equations for the assessment of the chest wall thickness induce large biases in the assessment of activity. For plutonium isotopes or 241Am the proportion of workers for whom the retained activity is within ± 10% of the reference one is smaller than 10%. The use of site-specific equations raises this proportion to 20% and 58% for plutonium and 241Am, respectively. Finally, for the studied population, when site-specific equations are used for the chest wall thickness, the standard uncertainties for the lung activity are 42% and 12.5%, for plutonium and 241Am, respectively. Due to the relatively large size of the studied population, these values are a relatively robust estimate of the uncertainties due to the assessment of the chest wall thickness for the current practice at this site. (paper)

  12. Endothelial wall thickness, cardiorespiratory fitness and inflammatory markers in obese and non-obese adolescents

    Directory of Open Access Journals (Sweden)

    Larissa R. Silva

    2014-03-01

    Full Text Available Background: Increased carotid intima-media thickness (c-IMT is considered a marker of early-onset atherosclerosis and it has been found in obese children and adolescents, but the risk factors associated with this population remain to be elucidated. Objective : To compare and verify the relationship between c-IMT, metabolic profile, inflammatory markers, and cardiorespiratory fitness in obese and non-obese children and adolescents. Method : Thirty-five obese subjects (19 boys and 18 non-obese subjects (9 boys, aged 10-16 years, were included. Anthropometry, body composition, blood pressure, maximal oxygen consumption (VO2max, and basal metabolic rate were evaluated. Serum glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR, blood lipids, C-reactive protein (CRP, and adiponectin were assessed. c-IMT was measured by ultrasound. Results: The results showed that c-IMT, triglycerides, insulin, HOMA-IR, and CRP values were significantly higher in the obese group than in the non-obese group, and high-density lipoprotein cholesterol (HDL-c, adiponectin, and VO2max values were significantly lower in the obese group than in the non-obese group. The c-IMT was directly correlated with body weight, waist circumference, % body fat, and HOMA-IR and inversely correlated with % free fat mass, HDL-c, and VO2max. Conclusions : Our findings show that c-IMT correlates not only with body composition, lipids, insulin resistance, and inflammation but also with low VO2max values in children and adolescents.

  13. A control systems approach to quantify wall shear stress normalization by flow-mediated dilation in the brachial artery.

    Directory of Open Access Journals (Sweden)

    Frank C G van Bussel

    Full Text Available Flow-mediated dilation is aimed at normalization of local wall shear stress under varying blood flow conditions. Blood flow velocity and vessel diameter are continuous and opposing influences that modulate wall shear stress. We derived an index FMDv to quantify wall shear stress normalization performance by flow-mediated dilation in the brachial artery. In 22 fasting presumed healthy men, we first assessed intra- and inter-session reproducibilities of two indices pFMDv and mFMDv, which consider the relative peak and relative mean hyperemic change in flow velocity, respectively. Second, utilizing oral glucose loading, we evaluated the tracking performance of both FMDv indices, in comparison with existing indices [i.e., the relative peak diameter increase (%FMD, the peak to baseline diameter ratio (Dpeak/Dbase, and the relative peak diameter increase normalized to the full area under the curve of blood flow velocity with hyperemia (FMD/shearAUC or with area integrated to peak hyperemia (FMD/shearAUC_peak]. Inter-session and intra-session reproducibilities for pFMDv, mFMDv and %FMD were comparable (intra-class correlation coefficients within 0.521-0.677 range. Both pFMDv and mFMDv showed more clearly a reduction after glucose loading (reduction of ~45%, p≤0.001 than the other indices (% given are relative reductions: %FMD (~11%, p≥0.074; Dpeak/Dbase (~11%, p≥0.074; FMD/shearAUC_peak (~20%, p≥0.016 and FMD/shearAUC (~38%, p≤0.038. Further analysis indicated that wall shear stress normalization under normal (fasting conditions is already far from ideal (FMDv << 1, which (therefore does not materially change with glucose loading. Our approach might be useful in intervention studies to detect intrinsic changes in shear stress normalization performance in conduit arteries.

  14. The Frequency and Energy of Snoring Sounds Are Associated with Common Carotid Artery Intima-Media Thickness in Obstructive Sleep Apnea Patients

    Science.gov (United States)

    Lee, Guo-She; Lee, Li-Ang; Wang, Chao-Yung; Chen, Ning-Hung; Fang, Tuan-Jen; Huang, Chung-Guei; Cheng, Wen-Nuan; Li, Hsueh-Yu

    2016-01-01

    Obstructive sleep apnea (OSA) is a known risk factor for atherosclerosis. We investigated the association of common carotid artery intima-media thickness (CCA-IMT) with snoring sounds in OSA patients. A total of 30 newly diagnosed OSA patients with no history of cardiovascular diseases were prospectively enrolled for measuring mean CCA-IMT with B-mode ultrasonography, body mass index, metabolic syndrome, 10-year cardiovascular disease risk score, high-sensitivity C-reactive protein, and homocysteine. Good-quality signals of full-night snoring sounds in an ordinary sleep condition obtained from 15 participants were further acoustically analyzed (Included group). All variables of interest were not significantly different (all p > 0.05) between the included and non-included groups except for diastolic blood pressure (p = 0.037). In the included group, CCA-IMT was significantly correlated with snoring sound energies of 0–20 Hz (r = 0.608, p = 0.036) and 652–1500 Hz (r = 0.632, p = 0.027) and was not significantly associated with that of 20–652 Hz (r = 0.366, p = 0.242) after adjustment for age and sex. Our findings suggest that underlying snoring sounds may cause carotid wall thickening and support the large-scale evaluation of snoring sound characters as markers of surveillance and for risk stratification at diagnosis. PMID:27469245

  15. The Frequency and Energy of Snoring Sounds Are Associated with Common Carotid Artery Intima-Media Thickness in Obstructive Sleep Apnea Patients.

    Science.gov (United States)

    Lee, Guo-She; Lee, Li-Ang; Wang, Chao-Yung; Chen, Ning-Hung; Fang, Tuan-Jen; Huang, Chung-Guei; Cheng, Wen-Nuan; Li, Hsueh-Yu

    2016-01-01

    Obstructive sleep apnea (OSA) is a known risk factor for atherosclerosis. We investigated the association of common carotid artery intima-media thickness (CCA-IMT) with snoring sounds in OSA patients. A total of 30 newly diagnosed OSA patients with no history of cardiovascular diseases were prospectively enrolled for measuring mean CCA-IMT with B-mode ultrasonography, body mass index, metabolic syndrome, 10-year cardiovascular disease risk score, high-sensitivity C-reactive protein, and homocysteine. Good-quality signals of full-night snoring sounds in an ordinary sleep condition obtained from 15 participants were further acoustically analyzed (Included group). All variables of interest were not significantly different (all p > 0.05) between the included and non-included groups except for diastolic blood pressure (p = 0.037). In the included group, CCA-IMT was significantly correlated with snoring sound energies of 0-20 Hz (r = 0.608, p = 0.036) and 652-1500 Hz (r = 0.632, p = 0.027) and was not significantly associated with that of 20-652 Hz (r = 0.366, p = 0.242) after adjustment for age and sex. Our findings suggest that underlying snoring sounds may cause carotid wall thickening and support the large-scale evaluation of snoring sound characters as markers of surveillance and for risk stratification at diagnosis. PMID:27469245

  16. Deposition of amyloid β in the walls of human leptomeningeal arteries in relation to perivascular drainage pathways in cerebral amyloid angiopathy☆

    Science.gov (United States)

    Keable, Abby; Fenna, Kate; Yuen, Ho Ming; Johnston, David A.; Smyth, Neil R.; Smith, Colin; Salman, Rustam Al-Shahi; Samarasekera, Neshika; Nicoll, James A.R.; Attems, Johannes; Kalaria, Rajesh N.; Weller, Roy O.; Carare, Roxana O.

    2016-01-01

    Deposition of amyloid β (Aβ) in the walls of cerebral arteries as cerebral amyloid angiopathy (CAA) suggests an age-related failure of perivascular drainage of soluble Aβ from the brain. As CAA is associated with Alzheimer's disease and with intracerebral haemorrhage, the present study determines the unique sequence of changes that occur as Aβ accumulates in artery walls. Paraffin sections of post-mortem human occipital cortex were immunostained for collagen IV, fibronectin, nidogen 2, Aβ and smooth muscle actin and the immunostaining was analysed using Image J and confocal microscopy. Results showed that nidogen 2 (entactin) increases with age and decreases in CAA. Confocal microscopy revealed stages in the progression of CAA: Aβ initially deposits in basement membranes in the tunica media, replaces first the smooth muscle cells and then the connective tissue elements to leave artery walls completely or focally replaced by Aβ. The pattern of development of CAA in the human brain suggests expansion of Aβ from the basement membranes to progressively replace all tissue elements in the artery wall. Establishing this full picture of the development of CAA is pivotal in understanding the clinical presentation of CAA and for developing therapies to prevent accumulation of Aβ in artery walls. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock. PMID:26327684

  17. Deposition of amyloid β in the walls of human leptomeningeal arteries in relation to perivascular drainage pathways in cerebral amyloid angiopathy.

    Science.gov (United States)

    Keable, Abby; Fenna, Kate; Yuen, Ho Ming; Johnston, David A; Smyth, Neil R; Smith, Colin; Al-Shahi Salman, Rustam; Samarasekera, Neshika; Nicoll, James A R; Attems, Johannes; Kalaria, Rajesh N; Weller, Roy O; Carare, Roxana O

    2016-05-01

    Deposition of amyloid β (Aβ) in the walls of cerebral arteries as cerebral amyloid angiopathy (CAA) suggests an age-related failure of perivascular drainage of soluble Aβ from the brain. As CAA is associated with Alzheimer's disease and with intracerebral haemorrhage, the present study determines the unique sequence of changes that occur as Aβ accumulates in artery walls. Paraffin sections of post-mortem human occipital cortex were immunostained for collagen IV, fibronectin, nidogen 2, Aβ and smooth muscle actin and the immunostaining was analysed using Image J and confocal microscopy. Results showed that nidogen 2 (entactin) increases with age and decreases in CAA. Confocal microscopy revealed stages in the progression of CAA: Aβ initially deposits in basement membranes in the tunica media, replaces first the smooth muscle cells and then the connective tissue elements to leave artery walls completely or focally replaced by Aβ. The pattern of development of CAA in the human brain suggests expansion of Aβ from the basement membranes to progressively replace all tissue elements in the artery wall. Establishing this full picture of the development of CAA is pivotal in understanding the clinical presentation of CAA and for developing therapies to prevent accumulation of Aβ in artery walls. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock. PMID:26327684

  18. A novel computerized tool to stratify risk in carotid atherosclerosis using kinematic features of the arterial wall.

    Science.gov (United States)

    Gastounioti, Aimilia; Makrodimitris, Stavros; Golemati, Spyretta; Kadoglou, Nikolaos P E; Liapis, Christos D; Nikita, Konstantina S

    2015-05-01

    Valid characterization of carotid atherosclerosis (CA) is a crucial public health issue, which would limit the major risks held by CA for both patient safety and state economies. This paper investigated the unexplored potential of kinematic features in assisting the diagnostic decision for CA in the framework of a computer-aided diagnosis (CAD) tool. To this end, 15 CAD schemes were designed and were fed with a wide variety of kinematic features of the atherosclerotic plaque and the arterial wall adjacent to the plaque for 56 patients from two different hospitals. The CAD schemes were benchmarked in terms of their ability to discriminate between symptomatic and asymptomatic patients and the combination of the Fisher discriminant ratio, as a feature-selection strategy, and support vector machines, in the classification module, was revealed as the optimal motion-based CAD tool. The particular CAD tool was evaluated with several cross-validation strategies and yielded higher than 88% classification accuracy; the texture-based CAD performance in the same dataset was 80%. The incorporation of kinematic features of the arterial wall in CAD seems to have a particularly favorable impact on the performance of image-data-driven diagnosis for CA, which remains to be further elucidated in future prospective studies on large datasets. PMID:24951709

  19. A Computed Tomographic Study on the Size and Bone Wall Thickness of the Maxillary Sinus in Normal, Preoperative and Postoperative Maxillary Sinusitis Patients

    International Nuclear Information System (INIS)

    To compare the size and bone wall thickness of the maxillary sinus in normal, preoperative and postoperative maxillary sinusitis patients. The author analyzed CT images of both left and right maxillary sinuses in 357 patients who visited Chonbuk National University Hospital between January 1997 and December 1998. The size and bone wall thickness of the maxillary sinus of normal, inflammatory and post-Caldwell-Luc groups were compared. The significant differences of transverse, maximum medio-lateral, maximum supero-inferior dimensions and medio-lateral dimension at nasal floor level between normal and post-Caldwell-Luc groups were found (P0.05). The significant differences of postero-lateral, infero-lateral and medial wall thickness between normal and post-Caldwell-Luc groups were found (P<0.05). The results of this study will aid in the diagnosis and treatment of maxillary sinus diseases and post operative treatment planning.

  20. Comparison of Kalman-filter-based approaches for block matching in arterial wall motion analysis from B-mode ultrasound

    Science.gov (United States)

    Gastounioti, A.; Golemati, S.; Stoitsis, J.; Nikita, K. S.

    2011-11-01

    Block matching (BM) has been previously used to estimate motion of the carotid artery from B-mode ultrasound image sequences. In this paper, Kalman filtering (KF) was incorporated in this conventional method in two distinct scenarios: (a) as an adaptive strategy, by renewing the reference block and (b) by renewing the displacements estimated by BM or adaptive BM. All methods resulting from combinations of BM and KF with the two scenarios were evaluated on synthetic image sequences by computing the warping index, defined as the mean squared error between the real and estimated displacements. Adaptive BM, followed by an update through the second scenario at the end of tracking, ABM_KF-K2, minimized the warping index and yielded average displacement error reductions of 24% with respect to BM. The same method decreased estimation bias and jitter over varying center frequencies by 30% and 64%, respectively, with respect to BM. These results demonstrated the increased accuracy and robustness of ABM_KF-K2 in motion tracking of the arterial wall from B-mode ultrasound images, which is crucial in the study of mechanical properties of normal and diseased arterial segments.

  1. Comparison of Kalman-filter-based approaches for block matching in arterial wall motion analysis from B-mode ultrasound

    International Nuclear Information System (INIS)

    Block matching (BM) has been previously used to estimate motion of the carotid artery from B-mode ultrasound image sequences. In this paper, Kalman filtering (KF) was incorporated in this conventional method in two distinct scenarios: (a) as an adaptive strategy, by renewing the reference block and (b) by renewing the displacements estimated by BM or adaptive BM. All methods resulting from combinations of BM and KF with the two scenarios were evaluated on synthetic image sequences by computing the warping index, defined as the mean squared error between the real and estimated displacements. Adaptive BM, followed by an update through the second scenario at the end of tracking, ABMKF-K2, minimized the warping index and yielded average displacement error reductions of 24% with respect to BM. The same method decreased estimation bias and jitter over varying center frequencies by 30% and 64%, respectively, with respect to BM. These results demonstrated the increased accuracy and robustness of ABMKF-K2 in motion tracking of the arterial wall from B-mode ultrasound images, which is crucial in the study of mechanical properties of normal and diseased arterial segments

  2. Three dimensional level set based semiautomatic segmentation of atherosclerotic carotid artery wall volume using 3D ultrasound imaging

    Science.gov (United States)

    Hossain, Md. Murad; AlMuhanna, Khalid; Zhao, Limin; Lal, Brajesh K.; Sikdar, Siddhartha

    2014-03-01

    3D segmentation of carotid plaque from ultrasound (US) images is challenging due to image artifacts and poor boundary definition. Semiautomatic segmentation algorithms for calculating vessel wall volume (VWV) have been proposed for the common carotid artery (CCA) but they have not been applied on plaques in the internal carotid artery (ICA). In this work, we describe a 3D segmentation algorithm that is robust to shadowing and missing boundaries. Our algorithm uses distance regularized level set method with edge and region based energy to segment the adventitial wall boundary (AWB) and lumen-intima boundary (LIB) of plaques in the CCA, ICA and external carotid artery (ECA). The algorithm is initialized by manually placing points on the boundary of a subset of transverse slices with an interslice distance of 4mm. We propose a novel user defined stopping surface based energy to prevent leaking of evolving surface across poorly defined boundaries. Validation was performed against manual segmentation using 3D US volumes acquired from five asymptomatic patients with carotid stenosis using a linear 4D probe. A pseudo gold-standard boundary was formed from manual segmentation by three observers. The Dice similarity coefficient (DSC), Hausdor distance (HD) and modified HD (MHD) were used to compare the algorithm results against the pseudo gold-standard on 1205 cross sectional slices of 5 3D US image sets. The algorithm showed good agreement with the pseudo gold standard boundary with mean DSC of 93.3% (AWB) and 89.82% (LIB); mean MHD of 0.34 mm (AWB) and 0.24 mm (LIB); mean HD of 1.27 mm (AWB) and 0.72 mm (LIB). The proposed 3D semiautomatic segmentation is the first step towards full characterization of 3D plaque progression and longitudinal monitoring.

  3. Determination of the chest wall thickness as calibration parameter for dosimetric partial-body counting; Bestimmung der Brustwandstaerke als Kalibrierparameter fuer dosimetrische Teilkoerpermessungen

    Energy Technology Data Exchange (ETDEWEB)

    Guen, H. [Fachhochschule Giessen-Friedberg, Giessen (Germany). Inst. fuer Medizinische Physik und Strahlenschutz; Karlsruher Institut fuer Technologie, Eggenstein-Leopoldshafen (Germany). Inst. fuer Strahlenforschung; Hegenbart, L. [Karlsruher Institut fuer Technologie, Eggenstein-Leopoldshafen (Germany). Inst. fuer Strahlenforschung; Breckow, J. [Fachhochschule Giessen-Friedberg, Giessen (Germany). Inst. fuer Medizinische Physik und Strahlenschutz

    2010-05-15

    The authors describe actual partial body measurements with Phoswich detectors in the in-vivo laboratory of the Institute for Technology in Karlsruhe. The chest wall thickness is estimated from the radio of body weight to body length. This formula includes several uncertainties. The aim of the project was the reduction of the uncertainties of the empirical formula using ultrasonography. This method allows an accuracy of plus or minus 1.1 mm for the determined chest wall thickness. Besides the experimental study several voxel models were used to determine the efficiency of modeled measuring systems. The voxel models reach the same accuracy as the ultrasound method.

  4. Peripheral vascular stiffness, assessed with two-dimensional speckle tracking versus the degree of coronary artery calcification, evaluated by tomographic coronary artery calcification index

    OpenAIRE

    Podgórski, Michał; GRZELAK, PIOTR; Szymczyk, Konrad; Szymczyk, Ewa; Drożdż, Jarosław; Stefańczyk, Ludomir

    2015-01-01

    Introduction Even in asymptomatic patients, the result of atherosclerosis progression is deterioration of the function and morphology of the artery wall. Two-dimensional speckle-tracking (2DST) is a sonographic technique that allows for precise evaluation of arterial wall compliance. Together with measurement of intima-media thickness (IMT), it can be applied for quick and non-invasive assessment of the progression of peripheral artery atherosclerosis. Material and methods Fifty-eight patient...

  5. Color doppler sonography of patients with temporal arteritis: Comparison with normal superficial temporal artery

    International Nuclear Information System (INIS)

    To evaluate the color doppler sonographic findings of superficial temporal artery of patients with temporal arteritis in comparison with normal superficial temporal artery. The superficial temporal arteries and their frontal and parietal branches were examined by color doppler sonography in 6 patients with temporal arteritis and 30 normal controls. Vessel diameter, vessel wall thickness, peak systolic velocity, end-diastolic velocity and resistive index in proximal and distal portion of superficial temporal arteries and their frontal and parietal branches were examined. For statistical analysis, Student's t-test was used and a p-value<0.01 was considered significant. Mean vessel wall thickness, peak systolic velocity in patients with temporal arteritis were 0.63 0.08 mm and 49.25 11.93 cm/sec,respectively inproximal superficial temporal arteries; 0.63 0.17 mm and 30.53 11.57 cm/sec in distal superficial temporal arteries. Mean vessel wall thickness of normal branches of superficial temporal arteries in patients with temporal arteries was 0.62 0.11 mm. The vessel wall superficial temporal arteries and their frontal branches in temporal arteries group was thicker than normal control group (p<0.01). The mean peak velocity of main superficial temporal arteries in temporal arteries group was significantly lower than normal control group (p<0.01). The vessel wall was hypoechoic in temporal arteries group. We obtained various color doppler sonographic findings in patients with temporal arteritis for comparison with normal group. The wall thickness, the peak systolic velocity and wall echogenicity of superficial temporal artery could be useful in diagnosis of temporal arteritis.

  6. Smooth muscle cell function and organization of the resistance artery wall

    NARCIS (Netherlands)

    B. Güvenç Tuna

    2014-01-01

    Remodeling of the vascular wall occurs in several cardiovascular pathologies. A structural change in diameter necessarily involves reorganization in both cellular and extracellular matrix components. The significance of matrix remodeling in vascular pathologies is well appreciated, while plasticity

  7. Mechanical properties of the aortic arterial wall during 24 hours: a preliminary study in conscious sheep

    International Nuclear Information System (INIS)

    Previous experiences in animals showed a different behavior between the variability of pressure, arterial diameter and elasticity when they were registered for a couple of hours. To better understand arterial mechanics variability, we propose to measure simultaneously aortic pressure and diameter during 24 hours in a sheep. For that purpose, we developed a portable prototype device. It allows continuously recording physiological signals throughout the day and storing them in a solid state memory for later analysis. Pulse wave velocity and Peterson modulus were assessed beat-to-beat as arterial stiffness indexes. We identified 53,762 heart beats during 24 hours that were separated into 2 groups: below or above median mean pressure (71 mmHg). Mean diameter, pulse wave velocity and Peterson modulus increased for higher pressure values (p<0.05) whereas heart rate slowed down (p<0.05). Pressure-diameter loops were successfully recreated all along the experience. This new methodology sets the basis for further experiences involving the estimation of 24 hours arterial mechanics variability.

  8. Numerical study of the coupling of two identification methods - thermal and electromagnetic - for the reconstruction of inclusions in thick walls

    Science.gov (United States)

    Le Touz, Nicolas; Dumoulin, Jean; Soldovieri, Francesco

    2016-04-01

    In this numerical study we present an approach allowing introducing a priori information in an identification method of internal thermal properties field for a thick wall using infrared thermography measurements. This method is based on a coupling with an electromagnetic reconstructing method which data are obtained from measurements of Ground Penetrating Radar (GPR) ([1], [2]). This new method aims at improving the accuracy of reconstructions performed by using only the thermal reconstruction method under quasi-periodic natural solicitation ([3], [4]). Indeed, these thermal reconstructions, without a priori information, have the disadvantage of being performed on the entire studied wall. Through the intake of information from GPR, it becomes possible to focus on the internal zones that may contain defects. These areas are obtained by defining subdomains around remarkable points identified with the GPR reconstruction and considered as belonging to a discontinuity. For thermal reconstruction without providing a priori information, we need to minimize a functional equal to a quadratic residue issued from the difference between the measurements and the results of the direct model. By defining search fields around these potential defects, and thus by forcing the thermal parameters further thereof, we provide information to the data to reconstruct. The minimization of the functional is then modified through the contribution of these constraints. We do not seek only to minimize a residue, but to minimize the overall residue and constraints, what changes the direction followed by the optimization algorithm in the space of thermal parameters to reconstruct. Providing a priori information may then allow to obtain reconstruction with higher residues but whose thermal parameters are better estimated, whether for locating potential defects or for the reconstructed values of these parameters. In particular, it is the case for air defects or more generally for defects having a

  9. Human coronary plaque wall thickness correlated positively with flow shear stress and negatively with plaque wall stress: an IVUS-based fluid-structure interaction multi-patient study

    OpenAIRE

    Fan, Rui; Tang, Dalin; Yang, Chun; Zheng, Jie; Bach, Richard; WANG, LIANG; Muccigrosso, David; Billiar, Kristen; Zhu, Jian; Ma, Genshan; Maehara, Akiko; Mintz, Gary S

    2014-01-01

    Background Atherosclerotic plaque progression and rupture are believed to be associated with mechanical stress conditions. In this paper, patient-specific in vivo intravascular ultrasound (IVUS) coronary plaque image data were used to construct computational models with fluid-structure interaction (FSI) and cyclic bending to investigate correlations between plaque wall thickness and both flow shear stress and plaque wall stress conditions. Methods IVUS data were acquired from 10 patients afte...

  10. Left ventricular wall thickness in patients with hypertrophic cardiomyopathy: a comparison between cardiac magnetic resonance imaging and echocardiography.

    Science.gov (United States)

    Corona-Villalobos, Celia P; Sorensen, Lars L; Pozios, Iraklis; Chu, Linda; Eng, John; Abraham, Maria Roselle; Abraham, Theodore P; Kamel, Ihab R; Zimmerman, Stefan L

    2016-06-01

    We assessed whether cardiac MRI (CMR) and echocardiography (echo) have significant differences measuring left ventricular (LV) wall thickness (WT) in hypertrophic cardiomyopathy (HCM) as performed in the clinical routine. Retrospectively identified, clinically diagnosed HCM patients with interventricular-septal (IVS) pattern hypertrophy who underwent CMR and echo within the same day were included. Left Ventricular WT was measured by CMR in two planes and compared to both echo and contrast echo (cecho). 72 subjects, mean age 50.7 ± 16.2 years, 68 % males. Interventricular septal WT by echo and CMR planes showed good to excellent correlation. However, measurements of the postero-lateral wall showed poor correlation. Bland-Altman plots showed greater maximal IVS WT by echo compared to CMR measurement [SAX = 1.7 mm (-5.8, 9.3); LVOT = 1.1 mm (-5.6, 7.8)]. Differences were smaller between cecho and CMR [SAX = 0.8 mm (-9.2, 10.8); LVOT = -0.2 mm (-10.0, 9.6)]. Severity of WT by quartiles showed greater differences between echo and SAX CMR WT compared to cecho. Echocardiography typically measures greater WT than CMR, with the largest differences in moderate to severe hypertrophy. Contrast echocardiography more closely approximates CMR measurements of WT. These findings have potential clinical implications for risk stratification of subjects with HCM. PMID:26896038

  11. Numerical Study of the Thermally Conductive Finite Thickness Walls Impact on Heat Transfer Regime in a Closed System in Conditions of Radiant Energy Supply

    Directory of Open Access Journals (Sweden)

    Nee A. E.

    2015-01-01

    Full Text Available Plane problem of thermogravitational convection in a closed rectangular cavity is numerically solved in conditions of radiant energy supply to the one of the boundaries. Differential heat transfer parameters (fields of temperatures and stream functions for the conjugate (only vertical walls, only horizontal, vertical and horizontal walls and the nonconjugate formulation are obtained. Temperature distributions in the Y direction in the cross section along the axis of symmetry showed that the presence of heat-conducting finite thickness walls leads to a redistribution of the energy which is accumulated by gas and enclosure structures.

  12. Non-Newtonian models for molecular viscosity and wall shear stress in a 3D reconstructed human left coronary artery.

    Science.gov (United States)

    Soulis, Johannes V; Giannoglou, George D; Chatzizisis, Yiannis S; Seralidou, Kypriani V; Parcharidis, George E; Louridas, George E

    2008-01-01

    The capabilities and limitations of various molecular viscosity models, in the left coronary arterial tree, were analyzed via: molecular viscosity, local and global non-Newtonian importance factors, wall shear stress (WSS) and wall shear stress gradient (WSSG). The vessel geometry was acquired using geometrically correct 3D intravascular ultrasound (3D IVUS). Seven non-Newtonian molecular viscosity models, plus the Newtonian one, were compared. The WSS distribution yielded a consistent LCA pattern for nearly all non-Newtonian models. High molecular viscosity, low WSS and low WSSG values occurred at the outer walls of the major bifurcation in proximal LCA regions. The Newtonian blood flow was found to be a good approximation at mid- and high-strain rates. The non-Newtonian Power Law, Generalized Power Law, Carreau and Casson and Modified Cross blood viscosity models gave comparable molecular viscosity, WSS and WSSG values. The Power Law and Walburn-Schneck models over-estimated the non-Newtonian global importance factor I(G) and under-estimated the area averaged WSS and WSSG values. The non-Newtonian Power Law and the Generalized Power Law blood viscosity models were found to approximate the molecular viscosity and WSS calculations in a more satisfactory way. PMID:17412633

  13. Assessment of Oxidative Stress Markers and Carotid Artery Intima-Media Thickness in Elderly Patients Without and with Coronary Artery Disease.

    Science.gov (United States)

    Madisetty, Murali Krishna; Kumaraswami, Konda; Katkam, Shivakrishna; Saumya, Kankanala; Satyanarayana Raju, Y; Chandra, Naval; Jyotsna, Maddury; Patnaik, Sujatha; Kutala, Vijay Kumar

    2016-07-01

    We aimed to assess whether measuring carotid intima-media thickness (CIMT) and oxidative stress markers such as protein carbonyls, malondialdehyde, nitrate and glutathione in plasma of elderly patients without and with coronary artery disease (CAD) identifies early risk for CAD. A total of 50 cases with cardiovascular risk factors over the age of 60 years without CAD, and 50 patients with angiographically documented CAD over the age of 60 years were included in the study. Control group consists of 200 healthy individuals without the risk factors. Demographic details were obtained from all the subjects and CIMT measured by high frequency ultrasound and oxidative stress markers such protein carbonyls, malondialdehyde and total glutathione were determined in plasma by spectrophotometric methods. The distribution of cardiovascular risk factors in without CAD and CAD cases were smokers (16 vs 56 %), hypertension (26 vs 64 %), diabetes (16 vs 56 %) and dyslipidemia (18 vs 58 %) and positive family history (4 vs 38 %). None of the control group had any cardiovascular risk factors. Among the CAD cases, 16 % had single vessel disease, 44 % had double vessel disease and 40 % had triple vessel disease. The CIMT was significantly increased in CAD cases as compared to cases without CAD and healthy controls. On the other hand, CIMT was significantly increased in cases without CAD as compared to healthy controls. CIMT also increased with the duration of diabetes in patients without CAD and severity of disease in CAD cases. The levels of oxidants like plasma malondialdehyde, protein carbonyls, were significantly elevated and antioxidant glutathione levels and nitrate levels were significantly reduced in cases with and without CAD as compared to healthy controls. Oxidative stress markers and CIMT was found to be significantly increased in patients with cardiovascular risk factors like diabetes, family history of CAD, dyslipidemia, hypertension and smoking when compared to

  14. Optimizing the imaging protocol for vivo coronary artery wall using high-resolution MIRI: An experimental study on porcine and human

    International Nuclear Information System (INIS)

    To optimize the MR imaging protocol for coronary arterial wall depiction in vitro and characterize the coronary atherosclerotic plaques. MRI examination was prospectively performed in ten porcine hearts in order to optimize the MR imaging protocol. Various surface coils were used for coronary arterial wall imaging with the same parameters. Then, the image parameters were further optimized for high-resolution coronary wall imaging. The signal-noise ratio (SNR) and contrast-noise ratio (CNR) of images were measured. Finally, 8 human cadaver hearts with coronary atherosclerotic plaques were prospectively performed with MRI examination using optimized protocol in order to characterize the coronary atherosclerotic plaques. The SNR and CNR of MR image with temporomandibular coil were the highest of various surface coils. High-resolution and high SNR and CNR for ex vivo coronary artery wall depiction can be achieved using temporomandibular coil with 512 x 512 in matrix. Compared with histopathology, the sensitivity and specificity of MRI for identifying advanced plaques were: type IV-V (lipid, necrosis, fibrosis), 94% and 95%; type VI (hemorrhage), 100% and 98%; type VII (calcification), 91% and 100%; and type VIII (fibrosis without lipid core), 100% and 98%, respectively. Temporomandibular coil appears to be dramatically superior to eight-channel head coil and knee coil for ex vivo coronary artery wall imaging, providing higher spatial resolution and improved the SNR. Ex vivo high-resolution MRI has capability to distinguish human coronary atherosclerotic plaque compositions and accurately classify advanced plaques.

  15. The Effects of Rituximab on Lipids, Arterial Stiffness and Carotid Intima-Media Thickness in Rheumatoid Arthritis.

    Science.gov (United States)

    Novikova, Diana S; Popkova, Tatiana V; Lukina, Galina V; Luchikhina, Elena L; Karateev, Dmitry E; Volkov, Alexander V; Novikov, Alexander A; Aleksandrova, Elena N; Nasonov, Evgeny L

    2016-02-01

    The aim of the study was to examine lipid profiles, arterial stiffness (AS), carotid intima-media thickness (cIMT), in 55 women with RA without overt cardiovascular disease (СVD) treated with rituximab (RTX).The following parameters were recorded before and 24 weeks after RTX therapy (2 infusions of 500 or 1,000 mg RTX intravenously, fortnightly): plasma total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, DAS 28-ESR, serum C-reactive protein (CRP), RF IgM, AS (SI - stiffness index, RI - reflection index) by digital volume pulse contour analysis (Micro Medical, UK), and common cIMT by high-resolution B-mode carotid ultrasound. Based on the European League Against Rheumatism (EULAR) criteria, patients were divided into two groups: 1) moderate/good response to RTX therapy after 24 weeks (41 patients, 75%), 2) no response to RTX therapy (14 patients, 25%). Effective RTX therapy resulted in 9% increase in TC, 23% increase in HDL-C and 14% decrease in atherogenic index, 57% decrease in SI and 24% decrease in RI. We observed a 9% decrease of cIMTmax at 24 weeks. The improvement of cardiovascular parameters was accompanied by statistically significant decreases of CRP, ESR, RF IgM and DAS 28 in group 1 (P < 0.05). There were not significant changes in lipid profile, AS parameters, and cIMT in group 2. Two infusions of RTX in case of moderate/good EULAR effect of therapy exerted favorable effects on lipid profile, AS and cIMT in women with RA without overt CVD. PMID:26839473

  16. The effects of apoA-I/C-III/A-IV, apoE and apoB polymorphisms on carotid artery intima-media thickness.

    Science.gov (United States)

    Nieminen, Tuomo; Kähönen, Mika; Lehtimäki, Terho

    2006-03-01

    Different apolipoprotein combinations explain most of the functional differences between plasma lipoproteins. This emphasizes the pivotal role of apolipoproteins in the homeostasis and physiological control of lipid metabolism. Genetic polymorphisms of apolipoprotein (apo)A-I/C-III/A-IV, apoE and apoB have been suggested to modulate plasma lipid levels as well as the risk of coronary artery disease and stroke. Carotid artery intima-media thickness has been shown to represent preclinical atherosclerosis and has, therefore, been used as a surrogate in quantifying the early stages of atherosclerosis. The effects of the polymorphisms in apoA-I/C-III/A-IV and apoB on carotid intima-media thickness are poorly known. The corresponding influence of apoE polymorphisms has been studied more extensively, but the results are not yet conclusive. In this review, these results are presented in detail and the potential reasons and mechanisms for the discrepancies are discussed. PMID:19804074

  17. Fracture analysis of a thick-walled pressure vessel under pressurized-thermal-shock loading (PTSE-2)

    International Nuclear Information System (INIS)

    Multi-transient pressurized-thermal-shock experiments (PTSEs) have been conducted under the NRC-sponsored Heavy-Section Steel Technology (HSST) program. The second test (PTSE-2) used a 2 1/4 CR-1 Mo steel (SA-387 grade 22) that had been given a special heat treatment to yield a low Charpy upper-shelf energy level and attendant low tearing resistance. The experiment included two combined thermal and pressure transients that gave rise to propagation and arrest of an initially long flaw that extended about 10% through the thick wall of the test cylinder. Detailed analyses of the experiment were performed using finite element techniques, an incremental thermo-elastic-plastic constitutive model and measured data. Analysis results indicate the material exhibited high initiation and crack-arrest toughness values, and the ability to inhibit crack propagation by warm prestressing. Cleavage initiation and arrest are modeled well by available fracture theories. However, calculations of ductile tearing based on resistance curves did not consistently predict the observed tearing

  18. Experimental and numerical study of fatigue crack propagation in thick-walled cylinder under cyclic hoop stress

    International Nuclear Information System (INIS)

    In present work, after finding the anisotropy resulting in dissimilar properties in different orientations of a thick-walled cylinder, experimental and numerical study was performed to reveal the fatigue crack growth behavior of the cylinder under cyclic hoop stress. Fatigue crack growth experiments were conducted on middle tension M(T) samples prepared in an orientation to simulate the hoop stress on the cylinder. The tests were conducted under constant amplitude loading at R ratio 0.1. The fatigue crack growth data was compiled and applied to simulate and predict the crack growth process using two dimensional parametric finite element technique. The fatigue crack propagation was simulated, based on linear elastic fracture mechanics and stress intensity factor determination. Both the experimental and numerical results of crack growth data, at stress levels of 10 to 40 percent of the yield stress of the material, were found in close agreement. The disparity observed was concluded in the range of statistical scatter in the experimental data. The crack growth rate and the fatigue life of the samples obtained from the experiments and the simulation were also in good agreement at all the stress levels analyzed. (author)

  19. Experimental and numerical study of fatigue crack propagation in a thick-walled cylinder under cyclic hoop stress

    International Nuclear Information System (INIS)

    In present work, after finding the anisotropy resulting in dissimilar properties in different orientations of a thick-walled cylinder, experimental and numerical study was performed to reveal the fatigue crack growth behavior of the cylinder under cyclic hoop stress. Fatigue crack growth experiments were conducted on middle tension M(T) samples prepared in an orientation to simulate the hoop stress on the cylinder. The tests were conducted under constant amplitude loading at R ratio 0.1. The fatigue crack growth data was compiled and applied to simulate and predict the crack growth process using two dimensional parametric finite element technique. The fatigue crack propagation was simulated, based on linear elastic fracture mechanics and stress intensity factor determination. Both the experimental and numerical results of crack growth data, at stress levels of 10 to 40 per cent of the yield stress of the material, were found in close agreement. The disparity observed was concluded in the range of statistical scatter in the experimental data. The crack growth rate and the fatigue life of the samples obtained from the experiments and the simulation were also in good agreement at all the stress levels analyzed

  20. Creep testing of thick-wall copper electron beam and friction stir welds at 75, 125 and 175 deg C

    International Nuclear Information System (INIS)

    Thick section copper canisters are planned to be used as a corrosion protection of nuclear waste disposal containers for long term underground deposit in Sweden. The copper canisters will have the top and possibly the bottom lid welded to the canister walls using electron beam or friction stir welding. Due to the high external hydrostatic pressure and the relatively high temperature of the waste during the first one hundred years the copper will creep. The creep process will close the manufacturing gap between the cast iron container and the copper canister. The creep ductility must be sufficient to avoid cracking of the weld and other parts of the canister. Specimens cut from the friction stir welds and the electron beam welds have been creep tested at temperatures ranging from 75 to 175 deg C. Cross-weld specimens were used for both friction stir and electron beam welds. Weld metal, heat affected zone and base metal were also studied for friction stir welds. The results for the electron beam welds show that the main creep deformation is concentrated to the weld metal where the failure takes place. Weld metal and most cross-weld tests of friction stir weld material show similar creep lives and ductility as base metal tests. Ductility at rupture was found to exceed 30% for friction stir weld specimens, and the Norton power law exponent was determined to be between 30 and 50

  1. Mechanical Performance and Failure Mechanism of Thick-walled Composite Connecting Rods Fabricated by Resin Transfer Molding Technique

    Science.gov (United States)

    Liu, Gang; Luo, Chuyang; Zhang, Daijun; Li, Xueqin; Qu, Peng; Sun, Xiaochen; Jia, Yuxi; Yi, Xiaosu

    2015-08-01

    A resin transfer molding technique was used to fabricate thick-walled composite connecting rods, and then the mechanical performance of the connecting rod was studied experimentally, at the same time the stress and failure index distributions were simulated numerically. The experimental results show that under a tensile load, the connecting rod first cracks near the vertex of the triangle areas at the two ends, and then the damage propagates along the interface between the main bearing beam and the triangle area as well as along the round angle of the triangle area. Whereas under a compressive load, the delamination primarily occurs at the corner of the U-shaped flange, and the final destruction is caused by the fracture of fibers in the main bearing beam. The simulated results reveal that the tensile failure is originated from the delamination at the round angle transition areas of the T-joints, and the failure strength is determined by the interlaminar strength. Whereas the compressive failure is caused by the fracture of fibers in the main bearing beam, and the failure strength of the structure is determined by the longitudinal compressive strength of the composite material. The simulated results are basically consistent with the experimental results. Hence the mechanical performance and failure mechanism of the complicated composite structure are revealed in great detail through the coupling of the two kinds of research methods, which is helpful for the optimal design of composite structures.

  2. Carotid and popliteal artery intima–media thickness in patients with poor oral hygiene and the association with acute-phase reactants

    OpenAIRE

    Uyar, Ihsan Sami; Besir Akpinar, Mehmet; Sahin, Veysel; Abacilar, Feyzi; Yurtman, Volkan; Fevzi Okur, Faik; Filiz Yasa, Elif

    2013-01-01

    Purpose The aim of this study was to evaluate whether poor oral hygiene is associated with carotid and popliteal arterial intima–media thickness, which is one of the predictors of future progression of sub-clinical atherosclerosis, and high-sensitivity C-reactive protein (hsCRP) and fibrinogen levels. Methods A specialised dentist checked the patients and selected 550 patients during periodontal examinations, according to their oral hygiene. The patients had no history of atherosclerotic dise...

  3. Brachial artery flow mediated dilatation and carotid intima media thickness measured by high resolution B-mode ultrasound in patients with rheumatoid arthritis

    OpenAIRE

    Mohamed A. Amin; Alsiagy A. Salama; Ashraf M. Elaggan; Salwa E. Elsayed

    2015-01-01

    Objectives: Firstly to assess the prevalence of subclinical atherosclerosis and endothelial dysfunction by high resolution ultrasound measurements of carotid intima media thickness (CIMT) and brachial artery flow mediated dilatation percentage (FMD%) in patients with rheumatoid arthritis (RA), secondly to analyze the correlation of CIMT and FMD% with different clinical and laboratory parameters, third aim was to analyze the relationship between CIMT and FMD%. Patients and methods: The pros...

  4. Intima-media thickness of carotid artery in middle-aged and old-aged people with different age and sex at nanchang city by ultrasound

    International Nuclear Information System (INIS)

    Objective: To investigate the intima-media thickness (IMT) of carotid artery in middleaged and old-aged people at different age and sex at Nanchang city and to establish the normal reference value. Methods: Excluding coronary heart disease, cerebrovascular disease and diabetes mellitus, 422 patients, above 30 years old were divided into the normal and the control groups based on whether the dangerous factors of atherosclerosis existed or not. Then each group was divided into 5 sub-groups according to age and sex and IMT of carotid artery measurement was perfrmed with ultrasound. Results: Means of IMT of carotid artery becomes higher as the age became older. IMT got predominant thick only when the age was more than 40 in male and 50 in female. Means of IMT is little higher than that in female,but there was no statistical difference between male and female group at age below 39 or above 50. Means of IMT in the control groups were higher than that in the normal groups and the differences was predominant. The ages older, the inner diameters of common carotid arteries wider, and became more predominant wide as the age was more than 50. Compared with female groups, the inner diameters of common carotid arteries of male groups were wider than those in the female groups'. The incidence rate of carotid atherosclerosis plaques was higher as the age became older, but the atherosclerosis plaques was not observed in population below 39 years old. In the population above 40 years old, the incidence rate of carotid atherosclerosis plaques was 5. 06% in the normal groups and 20. 60% in the control groups. No statistic differences exited in the incidence rate of carotid atherosclerosis plaques between the male and female groups. Carotid artery stenosis were observed i. e. five arteries were found in three control patients, and the stenosis degree exceed 50% of the diameter of artery. Conclusions: The IMT of common carotid arteries in the people at age of 40 and above 40 in the

  5. The methodology and software for definition of the utmost permissible decrease of the walls thickness of the pipelines subjected to erosive-corrosive wear (ECW)

    International Nuclear Information System (INIS)

    The methodology and software for assessment of utmost permissible decrease and strength of the walls thickness of the pipelines subjected to erosive-corrosive wear and prognosis of capacity for work of pipelines during definite operation period based on stress-strain state of structure in the defect zone are presented in this work

  6. The influence of artery wall curvature on the anatomical assessment of stenosis severity derived from fractional flow reserve: a computational fluid dynamics study.

    Science.gov (United States)

    Govindaraju, Kalimuthu; Viswanathan, Girish N; Badruddin, Irfan Anjum; Kamangar, Sarfaraz; Salman Ahmed, N J; Al-Rashed, Abdullah A A A

    2016-11-01

    This study aims to investigate the influence of artery wall curvature on the anatomical assessment of stenosis severity and to identify a region of misinterpretation in the assessment of per cent area stenosis (AS) for functionally significant stenosis using fractional flow reserve (FFR) as standard. Five artery models of different per cent AS severity (70, 75, 80, 85 and 90%) were considered. For each per cent AS severity, the angle of curvature of the arterial wall varied from straight to an increasingly curved model (0°, 30°, 60°, 90° and 120°). Computational fluid dynamics was performed under transient physiologic hyperemic flow conditions to investigate the influence of artery wall curvature on the pressure drop and the FFR. The findings in this study may be useful in in vitro anatomical assessment of functionally significant stenosis. The FFR decreased with increasing stenosis severity for a given curvature of the artery wall. Moreover, a significant decrease in FFR was found between straight and curved models discussed for a given severity condition. These findings indicate that the curvature effect was included in the FFR assessment in contrast to minimum lumen area (MLA) or per cent AS assessment. The MLA or per cent AS assessment may lead to underestimation of stenosis severity. From this numerical study, an uncertainty region could be evaluated using the clinical FFR cutoff value of 0.8. This value was observed at 81.98 and 79.10% AS for arteries with curvature angles of 0° and 120° respectively. In conclusion, the curvature of the artery should not be neglected in in vitro anatomical assessment. PMID:27052093

  7. Quantifying [{sup 18}F]fluorodeoxyglucose uptake in the arterial wall: the effects of dual time-point imaging and partial volume effect correction

    Energy Technology Data Exchange (ETDEWEB)

    Blomberg, Bjoern A. [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Odense University Hospital, Department of Nuclear Medicine, Odense (Denmark); Bashyam, Arjun; Ramachandran, Abhinay; Gholami, Saeid; Houshmand, Sina; Salavati, Ali; Werner, Tom; Alavi, Abass [Hospital of the University of Pennsylvania, Department of Radiology, Philadelphia, PA (United States); Zaidi, Habib [Geneva University Hospital, Division of Nuclear Medicine and Molecular Imaging, Geneva (Switzerland); University of Groningen, Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, Groningen (Netherlands)

    2015-08-15

    The human arterial wall is smaller than the spatial resolution of current positron emission tomographs. Therefore, partial volume effects should be considered when quantifying arterial wall {sup 18}F-FDG uptake. We evaluated the impact of a novel method for partial volume effect (PVE) correction with contrast-enhanced CT (CECT) assistance on quantification of arterial wall {sup 18}F-FDG uptake at different imaging time-points. Ten subjects were assessed by CECT imaging and dual time-point PET/CT imaging at approximately 60 and 180 min after {sup 18}F-FDG administration. For both time-points, uptake of {sup 18}F-FDG was determined in the aortic wall by calculating the blood pool-corrected maximum standardized uptake value (cSUV{sub MAX}) and cSUV{sub MEAN}. The PVE-corrected SUV{sub MEAN} (pvcSUV{sub MEAN}) was also calculated using {sup 18}F-FDG PET/CT and CECT images. Finally, corresponding target-to-background ratios (TBR) were calculated. At 60 min, pvcSUV{sub MEAN} was on average 3.1 times greater than cSUV{sub MAX} (P <.0001) and 8.5 times greater than cSUV{sub MEAN} (P <.0001). At 180 min, pvcSUV{sub MEAN} was on average 2.6 times greater than cSUV{sub MAX} (P <.0001) and 6.6 times greater than cSUV{sub MEAN} (P <.0001). This study demonstrated that CECT-assisted PVE correction significantly influences quantification of arterial wall {sup 18}F-FDG uptake. Therefore, partial volume effects should be considered when quantifying arterial wall {sup 18}F-FDG uptake with PET. (orig.)

  8. Quantifying [18F]fluorodeoxyglucose uptake in the arterial wall: the effects of dual time-point imaging and partial volume effect correction

    International Nuclear Information System (INIS)

    The human arterial wall is smaller than the spatial resolution of current positron emission tomographs. Therefore, partial volume effects should be considered when quantifying arterial wall 18F-FDG uptake. We evaluated the impact of a novel method for partial volume effect (PVE) correction with contrast-enhanced CT (CECT) assistance on quantification of arterial wall 18F-FDG uptake at different imaging time-points. Ten subjects were assessed by CECT imaging and dual time-point PET/CT imaging at approximately 60 and 180 min after 18F-FDG administration. For both time-points, uptake of 18F-FDG was determined in the aortic wall by calculating the blood pool-corrected maximum standardized uptake value (cSUVMAX) and cSUVMEAN. The PVE-corrected SUVMEAN (pvcSUVMEAN) was also calculated using 18F-FDG PET/CT and CECT images. Finally, corresponding target-to-background ratios (TBR) were calculated. At 60 min, pvcSUVMEAN was on average 3.1 times greater than cSUVMAX (P <.0001) and 8.5 times greater than cSUVMEAN (P <.0001). At 180 min, pvcSUVMEAN was on average 2.6 times greater than cSUVMAX (P <.0001) and 6.6 times greater than cSUVMEAN (P <.0001). This study demonstrated that CECT-assisted PVE correction significantly influences quantification of arterial wall 18F-FDG uptake. Therefore, partial volume effects should be considered when quantifying arterial wall 18F-FDG uptake with PET. (orig.)

  9. Quantitative analysis of left ventricular wall motion at exercise stress in myocardial infarction with single vessel coronary artery disease

    International Nuclear Information System (INIS)

    The wall site involved by myocardial infarction (MI) is one of major factors to determine a cardiac pump function of the patient. Generally, anterior MI has a lower cardiac function at rest than inferior MI. However, the difference in cardiac function during exercise between anterior MI and inferior MI is controversial. To clarify the difference, regional wall motion at infarcted area and noninfarcted area were examined quantitatively by exercise radionuclide ventriculography in 23 patients with MI. MI group consisted of 13 patients with isolated left anterior descending coronary artery (LAD) lesion and 10 patients with isolated right coronary artery (RCA) lesion without residual ischemia, and was compared to 12 normal controls (NC) and also to 12 patients with multivessel (MV) lesions. Left ventricular ejection fraction (EF) and regional EF (REF) as parameters of amplitude, and standard deviation (SD) of mean of left ventricular phase angle, regional SD (RSD) as parameters of asynchrony were obtained. At rest, infarcted area showed significant decrease in REF and increase in RSD but non-infarcted area in LAD group showed significant decrease in REF. MI group revealed increase in EF and REF, even at infarcted area significantly during exercise, but LAD group showed less increase in EF than RCA group. MI group had no significant changes in SD and RSD during exercise. MV group had significant increase in SD but no significant changes in EF during exercise. At peak exercise, non-infarcted area in RCA group showed the same degree of increase in REF as the same segments in NC. But non-infarcted area in LAD group showed significantly less increase in REF than the same segments in NC. In conclusion, the difference in response of EF between anterior MI and inferior MI was greatly related with REF at non-infarcted area rather than infarcted area. (author)

  10. Arterialization and anomalous vein wall remodeling in varicose veins is associated with upregulated FoxC2-Dll4 pathway.

    Science.gov (United States)

    Surendran, Sumi; S Ramegowda, Kalpana; Suresh, Aarcha; Binil Raj, S S; Lakkappa, Ravi Kumar B; Kamalapurkar, Giridhar; Radhakrishnan, N; C Kartha, Chandrasekharan

    2016-04-01

    Varicose veins of lower extremities are a heritable common disorder. Mechanisms underlying its pathogenesis are still vague. Structural failures such as valve weakness and wall dilatation in saphenous vein result in venous retrograde flow in lower extremities of body. Reflux of blood leads to distal high venous pressure resulting in distended veins. In an earlier study, we observed a positive association between c.-512C>T FoxC2 gene polymorphism and upregulated FoxC2 expression in varicose vein specimens. FoxC2 overexpression in vitro in venous endothelial cells resulted in the elevated mRNA expression of arterial endothelial markers such as Delta-like ligand 4 (Dll4) and Hairy/enhancer-of-split related with YRPW motif protein 2 (Hey2). We hypothesized that an altered FoxC2-Dll4 signaling underlies saphenous vein wall remodeling in patients with varicose veins. Saphenous veins specimens were collected from 22 patients with varicose veins and 20 control subjects who underwent coronary artery bypass grafting. Tissues were processed for paraffin embedding and sections were immunostained for Dll4, Hey2, EphrinB2, α-SMA, Vimentin, and CD31 antigens and examined under microscope. These observations were confirmed by quantitative real-time PCR and western blot analysis. An examination of varicose vein tissue specimens by immunohistochemistry indicated an elevated expression of Notch pathway components, such as Dll4, Hey2, and EphrinB2, and smooth muscle markers, which was further confirmed by gene and protein expression analyses. We conclude that the molecular alterations in Dll4-Hey2 signaling are associated with smooth muscle cell hypertrophy and hyperplasia in varicose veins. Our observations substantiate a significant role for altered FoxC2-Dll4 signaling in structural alterations of saphenous veins in patients with varicose veins. PMID:26808710

  11. 18F-fluoroethylcholine uptake in arterial vessel walls and cardiovascular risk factors. Correlation in a PET-CT study

    International Nuclear Information System (INIS)

    Fluorine-labelled choline derivatives were recently suggested as agents for visualizing vulnerable atherosclerotic plaques. We therefore aimed to evaluate the association between 18F-fluorethylcholine (FEC) uptake in the wall of large arteries, where calcification was also measured, with the presence of cardiovascular risk factors and occurrence of prior cardiovascular events. Detailed clinical information, including common cardiovascular risk factors, was obtained retrospectively in 60 prostate cancer patients examined with whole-body FEC PET-CT. In each patient, we calculated the mean blood pool-corrected SUV, as well as the mean target-to-background ratio (TBR), in addition to the sum of calcified plaques (CPsum) from six major vessels: ascending and descending aorta, aortic arch, abdominal aorta, and both iliac arteries. As reported previously, the CPsum correlated significantly with cardiovascular risk factors, in contrast to mean SUV or TBR scores, which did not show any significance with the presence of cardiovascular risk factors. There was no correlation between CPsum, mean TBR or SUV, nor was there any significant association of CPsum, mean TBR or SUV with the prior occurrence of cardio- or cerebrovascular events. Contrary to a recent report, we found in our rather large cohort of elderly prostate cancer patients no significant association between FEC uptake in large vessels and atherosclerotic plaque burden, or the presence of cardiovascular risk factors. In line with prior reports on structural changes in vessels, increased calcified atherosclerotic plaque burden was strongly associated with the occurrence of common cardiovascular risk factors. (orig.)

  12. Low prevalence of significant carotid artery disease in Iranian patients undergoing elective coronary artery bypass

    Directory of Open Access Journals (Sweden)

    Karimi Fatemeh

    2007-01-01

    Full Text Available Abstract Background Coronary artery bypass grafting ranks as one of the most frequent operations worldwide. The presence of carotid artery stenosis may increase the stroke rate in the perioperative period. Routine preoperative noninvasive assessment of the carotid arteries are recommended in many institutions to reduce the stroke rate. Methods 271 consecutive patients undergoing coronary artery bypass grafting at Shaheed Madani hospital of Tabriz, Iran (age, 58.5 Y; 73.1% male underwent preoperative ultrasonography for assessment of carotid artery wall thickness. Results Plaque in right common, left common, right internal and left internal carotid arteries was detected in 4.8%, 7.4%, 43.2% and 42.1% of patients respectively. 5 patients (1.8% had significant ( Conclusion Consecutive Iranian patients undergoing elective coronary artery bypass surgery show a very low prevalence of significant carotid artery disease.

  13. Influence of Formalin Fixation Prior to in vitro Ultrasound Examination of Porcine Arteries

    DEFF Research Database (Denmark)

    Wilhjelm, Jens E.; Vogt, Katja; Jespersen, Søren Kragh;

    1996-01-01

    This paper reports on an investigation of the influence on the echosignal from porcine artery walls due to two different formalin fixationprocedures. The lumen diameter, the wall thickness and the mean echogenicitywere calculated. In general, the fixation resulted in a more rigid wall...

  14. Effects of External and Internal Hyperthermia on LDL Transport and Accumulation Within an Arterial Wall in the Presence of a Stenosis.

    Science.gov (United States)

    Iasiello, Marcello; Vafai, Kambiz; Andreozzi, Assunta; Bianco, Nicola; Tavakkoli, Fatemeh

    2015-07-01

    Effects of hyperthermia on transport of low-density lipoprotein (LDL) through a stenosed arterial wall are analyzed comprehensively in the present work. The realistic and pertinent aspects of an arterial wall is represented by a multi-layer model, with a proper representation of the thickened intima region due to the atherosclerotic plaque formation. Effects of external and internal hyperthermia on LDL concentration levels are established along with the range of influence of these effects. Various modules of the current work are comprehensively compared with pertinent literature and are found to be in excellent agreement. The effects of external and internal hyperthermia as well as the load level and the axial location of the plaque formation on LDL transport and accumulation for a stenosed artery are established in this work. PMID:25520050

  15. Parameter sensitivity analysis: application to model predictions of transport parameters governing arterial wall uptake of 14C-4 cholesterol

    International Nuclear Information System (INIS)

    The authors have applied nonlinear (Marquardt) regression techniques to concentration profiles of 14C-4 cholesterol within the arterial wall of excised canine carotids perfused for two hours under various hemodynamic conditions. The resulting estimates of the transport parameters of Peclet number (Pe), effective diffusivity (D), endothelial vesicular Biot number (Be), and endothelial phenomenological rejection coefficient (Re) serve as input to a sensitivity analysis of the inter-dependence of model parameters. Here the best-fit value of each parameter estimate is perturbed by 10% and the resulting change in the predicted concentration profile used to calculate individual parameter sensitivities according to algorithms defined in the text authored by P.M. Frank. Their results indicate that the parameters Be and Re are indistinguishable at all locations within the wall substance (x/L) except the endothelial cell border (x/L=0). A similar finding is true for the parameter pair Pe-D when x/L > 0.4, i.e. beyond the medial-adventitial junction. The implications are that the present mathematical model be modified to exclude an assessment of Be, especially when the anatomic integrity of the endothelial layer is compromised, and that perfusion times be extended to allow advancement of convective and diffusive fronts into the adventitia

  16. Influence of radiation dose and reconstruction algorithm in MDCT assessment of airway wall thickness: A phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Cardona, Daniel [Department of Medical Physics, University of Wisconsin-Madison School of Medicine and Public Health, 1111 Highland Avenue, Madison, Wisconsin 53705 (United States); Nagle, Scott K. [Department of Medical Physics, University of Wisconsin-Madison School of Medicine and Public Health, 1111 Highland Avenue, Madison, Wisconsin 53705 (United States); Department of Radiology, University of Wisconsin-Madison School of Medicine and Public Health, 600 Highland Avenue, Madison, Wisconsin 53792 (United States); Department of Pediatrics, University of Wisconsin-Madison School of Medicine and Public Health, 600 Highland Avenue, Madison, Wisconsin 53792 (United States); Li, Ke; Chen, Guang-Hong, E-mail: gchen7@wisc.edu [Department of Medical Physics, University of Wisconsin-Madison School of Medicine and Public Health, 1111 Highland Avenue, Madison, Wisconsin 53705 (United States); Department of Radiology, University of Wisconsin-Madison School of Medicine and Public Health, 600 Highland Avenue, Madison, Wisconsin 53792 (United States); Robinson, Terry E. [Department of Pediatrics, Stanford School of Medicine, 770 Welch Road, Palo Alto, California 94304 (United States)

    2015-10-15

    Purpose: Wall thickness (WT) is an airway feature of great interest for the assessment of morphological changes in the lung parenchyma. Multidetector computed tomography (MDCT) has recently been used to evaluate airway WT, but the potential risk of radiation-induced carcinogenesis—particularly in younger patients—might limit a wider use of this imaging method in clinical practice. The recent commercial implementation of the statistical model-based iterative reconstruction (MBIR) algorithm, instead of the conventional filtered back projection (FBP) algorithm, has enabled considerable radiation dose reduction in many other clinical applications of MDCT. The purpose of this work was to study the impact of radiation dose and MBIR in the MDCT assessment of airway WT. Methods: An airway phantom was scanned using a clinical MDCT system (Discovery CT750 HD, GE Healthcare) at 4 kV levels and 5 mAs levels. Both FBP and a commercial implementation of MBIR (Veo{sup TM}, GE Healthcare) were used to reconstruct CT images of the airways. For each kV–mAs combination and each reconstruction algorithm, the contrast-to-noise ratio (CNR) of the airways was measured, and the WT of each airway was measured and compared with the nominal value; the relative bias and the angular standard deviation in the measured WT were calculated. For each airway and reconstruction algorithm, the overall performance of WT quantification across all of the 20 kV–mAs combinations was quantified by the sum of squares (SSQs) of the difference between the measured and nominal WT values. Finally, the particular kV–mAs combination and reconstruction algorithm that minimized radiation dose while still achieving a reference WT quantification accuracy level was chosen as the optimal acquisition and reconstruction settings. Results: The wall thicknesses of seven airways of different sizes were analyzed in the study. Compared with FBP, MBIR improved the CNR of the airways, particularly at low radiation dose

  17. Influence of radiation dose and reconstruction algorithm in MDCT assessment of airway wall thickness: A phantom study

    International Nuclear Information System (INIS)

    Purpose: Wall thickness (WT) is an airway feature of great interest for the assessment of morphological changes in the lung parenchyma. Multidetector computed tomography (MDCT) has recently been used to evaluate airway WT, but the potential risk of radiation-induced carcinogenesis—particularly in younger patients—might limit a wider use of this imaging method in clinical practice. The recent commercial implementation of the statistical model-based iterative reconstruction (MBIR) algorithm, instead of the conventional filtered back projection (FBP) algorithm, has enabled considerable radiation dose reduction in many other clinical applications of MDCT. The purpose of this work was to study the impact of radiation dose and MBIR in the MDCT assessment of airway WT. Methods: An airway phantom was scanned using a clinical MDCT system (Discovery CT750 HD, GE Healthcare) at 4 kV levels and 5 mAs levels. Both FBP and a commercial implementation of MBIR (VeoTM, GE Healthcare) were used to reconstruct CT images of the airways. For each kV–mAs combination and each reconstruction algorithm, the contrast-to-noise ratio (CNR) of the airways was measured, and the WT of each airway was measured and compared with the nominal value; the relative bias and the angular standard deviation in the measured WT were calculated. For each airway and reconstruction algorithm, the overall performance of WT quantification across all of the 20 kV–mAs combinations was quantified by the sum of squares (SSQs) of the difference between the measured and nominal WT values. Finally, the particular kV–mAs combination and reconstruction algorithm that minimized radiation dose while still achieving a reference WT quantification accuracy level was chosen as the optimal acquisition and reconstruction settings. Results: The wall thicknesses of seven airways of different sizes were analyzed in the study. Compared with FBP, MBIR improved the CNR of the airways, particularly at low radiation dose

  18. Association of clinical androgen excess with radial artery intima media thickness in women with polycystic ovary syndrome.

    Science.gov (United States)

    Yilmaz, S A; Kebapcilar, A; Koplay, M; Kerimoglu, O S; Pekin, A T; Gencoglu, B; Dogan, N U; Celik, C

    2015-06-01

    This study explores the relationship between clinical cardiovascular risk factors and clinical androgen excess, with direct comparison to radial artery intima media thickness (rIMT). rIMT of 91 patients with polycystic ovary syndrome (PCOS) were compared with 72 healthy women. Patients were divided into three groups with regard to body mass index (BMI). Group1 = 56 women (31 controls and 25 PCOS) with low BMI(18-22.49 kg/m(2)), Group2 = 36 women (15 controls and 21 PCOS) with normal BMI (22.5-24.99 kg/m(2)) and Group3 = 71 women (26 controls and 45 PCOS) with high BMI (25-30 kg/m(2)). rIMT was significantly higher in patients with PCOS (p = 0.007). rIMT was significantly higher group1 and group3 in patients with PCOS compared to controls (p = 0.007 and p = 0.042, respectively). There was a significant positive association between rIMT levels and fT in women with PCOS in group1 (r = 0.24, p = 0.04). rIMT levels correlated to fT levels in women with PCOS in group3 (r = 0.32, p = 0.03). Modified Ferriman-Gallwey (mFG) scores demonstrated a positive association with free testosterone, total testosterone, free androgen index, waist circumference (WC), LH levels, insulin levels, Homeostasis Model Assessment index(HOMA-IR), rIMT and a negative correlation with sex hormone binding globulin in group1 and group2. mFG scores demonstrated a positive association with free testosterone (r = 0.33, p = 0.029) in group3, but no association was found between mFG and WC, HOMA-IR in group3. Our findings indicate that clinical androgen excess may be associated with cardiovascular disease in patients with PCOS. PMID:26213862

  19. Blood donation, body iron status and carotid intima-media thickness

    NARCIS (Netherlands)

    Engberink, M.F.; Geleijnse, J.M.; Durga, J.; Swinkels, D.W.; Kort, de W.L.A.M.; Schouten, E.G.; Verhoef, P.

    2008-01-01

    Iron could promote free radical formation, which may lead to injury of the arterial wall and atherosclerosis. Blood donation may reduce cardiovascular risk by lowering body iron status. We collected data on blood donation history and intima-media thickness of the common carotid artery (CIMT) in 819

  20. Arterial endothelial function measurement method and apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Maltz, Jonathan S; Budinger, Thomas F

    2014-03-04

    A "relaxoscope" (100) detects the degree of arterial endothelial function. Impairment of arterial endothelial function is an early event in atherosclerosis and correlates with the major risk factors for cardiovascular disease. An artery (115), such as the brachial artery (BA) is measured for diameter before and after several minutes of either vasoconstriction or vasorelaxation. The change in arterial diameter is a measure of flow-mediated vasomodification (FMVM). The relaxoscope induces an artificial pulse (128) at a superficial radial artery (115) via a linear actuator (120). An ultrasonic Doppler stethoscope (130) detects this pulse 10-20 cm proximal to the point of pulse induction (125). The delay between pulse application and detection provides the pulse transit time (PTT). By measuring PTT before (160) and after arterial diameter change (170), FMVM may be measured based on the changes in PTT caused by changes in vessel caliber, smooth muscle tone and wall thickness.

  1. Influences of lumped passes on welding residual stress of a thick-walled nuclear rotor steel pipe by multipass narrow gap welding

    International Nuclear Information System (INIS)

    Highlights: • The internal residual stress of the thick-walled pipe is measured by using the local removal blind hole method. • Two lumped-pass models are developed to reduce computational cost. • The effect of lumped passes on the welding residual stress is discussed. • Reasonable lumped-pass model can guarantee the accuracy and improve the computational efficiency. - Abstract: The purpose of this study is to investigate the effect of the lumped passes simulation on the distribution of residual stresses before and after heat treatment in a thick-walled nuclear power rotor pipe with a 89-pass narrow gap welding process. The local removal blind hole method was used to measure internal residual stress of the thick-walled pipe after post weld heat treatment (PWHT). Based on the ANSYS software, a two-dimensional axisymmetric finite element model is employed. Two lumped-pass models of M-5th model (five weld beads as one lumped pass) and M-10th model (ten weld beads as one lumped pass) were developed to reduce computational cost. Based on the results in this study, the distributions of residual stresses of a thick-walled welded pipe before and after PWHT are developed. Meanwhile, the distribution of the through-wall axial residual stress along the weld center line is demonstrated to be a self-equilibrating type. In addition, the investigation results show that reasonable and reliable lumped-pass model can not only guarantee the accuracy of the simulated results, but also improve the computational efficiency in the thermo-elastic–plastic FE analysis procedure. Therefore, from the viewpoint of engineering application the developed lumped-pass computational procedure is a promising and useful method to predict residual stress of large and complex welded structures

  2. Utilization of TIG orbital narrow-gap welding in the field of pre-processing and assembly of thick-walled pipes in the field of thick-walled pipes in the field of power plants; Einsatz des WIG-Orbital-Engspaltschweissens im Bereich der Vorfertigung und der Montage dickwandiger Rohre im Kraftwerksbereich

    Energy Technology Data Exchange (ETDEWEB)

    Rosenfeld, D. [Kraftanlagen Muenchen GmbH, Moosinning (Germany)

    2009-07-01

    This general review describes the types of application of the TIG orbital narrow-gap welding for thick-walled power station pipings. For the advancement of the procedure regarding to the performance and to the training of orbital welders, still large efforts are necessary. Because not only within the range of the thick-walled power station pipings, but also within the range of chemistry and mechanical engineering, the procedure for thick-walled construction units is applicable. By means of the presented activities, a basis is created in order to provide efficiently and qualitatively high-quality welding seams within the range of the high pressure pipings in the power plant construction. Within the materials of the next generation, the parameter windows will become still smaller the reaching of the necessary characteristics. Within the orbital welding engineering, these small parameter windows can be kept surely.

  3. A model of smooth muscle cell synchronization in the arterial wall

    DEFF Research Database (Denmark)

    Jacobsen, Jens Christian Brings; Aalkjær, Christian; Nilsson, Holger;

    2007-01-01

    Vasomotion is a rhythmic variation in microvascular diameter. Although known for more than 150 years, the cellular processes underlying the initiation of vasomotion are not fully understood. In the present study a model of a single cell is extended by coupling a number of cells into a tube. The...... membrane potential and flow of current through gap junctions. The amplitude of these oscillations in potential grows with increasing [cGMP], and, past a certain threshold, they become strong enough to entrain all cells in the vascular wall, thereby initiating sustained vasomotion. In this state there is a...... rhythmic flow of calcium through voltage-sensitive calcium channels into the cytoplasm, making the frequency of established vasomotion sensitive to membrane potential. It is concluded that electrical coupling through gap junctions is likely to be responsible for the rapid synchronization across a large...

  4. A model of smooth muscle cell synchronization in the arterial wall

    DEFF Research Database (Denmark)

    Jacobsen, Jens Christian; Aalkjær, Christian; Nilsson, Holger;

    2007-01-01

    Vasomotion is a rhythmic variation in microvascular diameter. Although known for more than 150 years, the cellular processes underlying initiation of vasomotion are not fully understood. In the present study a model of a single cell is extended by coupling a number of cells into a tube. The...... associated with rhythmic variation in membrane potential and flow of current through gap junctions. The amplitude of these oscillations in potential grows with increasing [cGMP], and, past a certain threshold, they become strong enough to entrain all cells in the vascular wall, thereby initiating sustained...... vasomotion. In this state there is a rhythmic flow of calcium through voltage-sensitive calcium channels into the cytoplasm, making the frequency of established vasomotion sensitive to membrane potential. It is concluded that electrical coupling through gap junctions is likely to be responsible for the rapid...

  5. Heterogeneity and weak coupling may explain the synchronization characteristics of cells in the arterial wall

    DEFF Research Database (Denmark)

    Jacobsen, Jens Christian Brings; Aalkjær, Christian; Matchkov, Vladimir V; Nilsson, Holger; Holstein-Rathlou, N.-H.; Freiberg, Jacob J

    2008-01-01

    development of force known as vasomotion. We present experimental data showing a considerable heterogeneity in cellular calcium dynamics in the vascular wall. In stimulated vessels, some SMCs remain quiescent, whereas others display waves of variable frequency. At the onset of vasomotion, all SMCs are...... enrolled into synchronized oscillation.Simulations of coupled SMCs show that the experimentally observed cellular recruitment, the presence of quiescent cells and the variation in oscillation frequency may arise if the cell population is phenotypically heterogeneous. In this case, quiescent cells can be...... entrained at the onset of vasomotion by the collective driving force from the synchronized oscillations in the membrane potential of the surrounding cells. Partial synchronization arises with an increase in the concentration of cyclic guanosine monophosphate, but in a heterogeneous cell population complete...

  6. Evaluación del espesor parietal relativo en la especie canina Evaluation of relative wall thickness in dogs

    Directory of Open Access Journals (Sweden)

    C. Lightowler

    2005-12-01

    Full Text Available Tanto los fenómenos patológicos como el ejercicio y entrenamiento promueven en el corazón fenómenos de adaptación, que varían según el mecanismo que los promueve. Uno de los mecanismos que se encuentra siempre en la adaptación cardiaca es la hipertrofia del miocardio. El grado de hipertrofia puede evaluarse midiendo la masa miocárdica ventricular izquierda. Sin embargo este parámetro evalúa la cantidad de hipertrofia, pero no la manera en que ésta se distribuye. Dicha distribución puede calcularse por medio del índice ecocardiográfico conocido como espesor parietal relativo (EPR. En este trabajo, los autores presentan la técnica ecocardiográfica para la evaluación del EPR en el perro y su valor normal promedio. Los resultados obtenidos fueron los siguientes: Media: 0,482; Desviación estándar: 0,098; Coeficiente de variación: 18,37%; Valor mínimo: 0,355; Primer cuartil: 0,407; Mediana: 0,459; Tercer cuartil: 0,528; Valor máximo: 0,728. Asimismo, se verificó la inexistencia de regresión lineal entre el EPR y el peso corporal.As much as the pathological phenomena the exercise and training promote in the heart adaptation phenomena, which vary according to the mechanism that promotes them. One of the mechanisms that is always present in cardiac adaptation is hypertrophy of myocardium. The degree of hypertrophy can be evaluated measuring the left ventricular myocardial mass. Nevertheless this parameter measures the amount of hypertrophy, but not how it is distributed; this can be evaluated by means of relative wall thickness (RWT index. In the present study the authors describe the echocardiography technique for the evaluation of the RWT in the dog and present its normal mean value. The results obtained were the following: Mean: 0,482; Standard deviation: 0,098; Coefficient of variation: 18,37%; Minimum value: 0,355; First quartile: 0,407; Median: 0,459; Third quartile: 0,528; Maximum value: 0,728. Also was verified the

  7. Changes in left ventricular function and wall thickness in heart transplant recipients and their relation to acute rejection: an assessment by digitised M mode echocardiography

    OpenAIRE

    Mannaerts, H F J; Balk, Aggie; Simoons, Maarten; Tijssen, Jan,; Borden, S.G.; Sutherland, G. R.; Roelandt, Jos; Zondervan, Pieter

    1992-01-01

    textabstractOBJECTIVE--Assessment of changes in left ventricular diastolic function and wall thickness after heart transplantation to verify whether these changes predicted acute rejection assessed by endomyocardial biopsy. DESIGN--Follow up according to a predefined protocol of consecutive patients from the first week after transplantation. SETTING--Heart transplantation unit of the Thoraxcentre, University Hospital Rotterdam Dijkzigt, The Netherlands. PATIENTS--All 32 patients undergoing or...

  8. Estimation of PSD Shifts for High-Resolution Metrology of Thickness Micro-Changes with Possible Applications in Vessel Walls and Biological Membrane Characterization

    OpenAIRE

    Abelardo Ruiz; Héctor Calás; Tomás Gómez; Javier Brum; Carlos Negreira; Ivonne Bazán; Antonio Ramos; José Manuel de la Rosa

    2012-01-01

    Achieving accurate measurements of inflammation levels in tissues or thickness changes in biological membranes (e.g., amniotic sac, parietal pleura) and thin biological walls (e.g., blood vessels) from outside the human body, is a promising research line in the medical area. It would provide a technical basis to study the options for early diagnosis of some serious diseases such as hypertension, atherosclerosis or tuberculosis. Nevertheless, achieving the aim of non-invasive measurement of th...

  9. [New echocardiographic para-apical technic for determining the size and thickness of the wall of the right ventricle in probands and patients with dilated cardiomyopathy].

    Science.gov (United States)

    Dyczynski, J; Schweitzer, L

    1987-12-01

    To evaluate the right ventricular size and free wall thickness a new echocardiographic para-apical technique was developed. All cases were examined from the para-apical window in the extreme left lateral decubitus position, on a special mattress that allowed us to investigate the total apical region. The para-apical transducer position makes it possible to cut the right ventricle cross-sectionally in serial bread-loafing fashion from the apex to the base, like the left ventricle. In this way, using the M-mode technique, either diameters and/or right ventricular free wall thickness as well as shortening fraction could be estimated. To estimate the usefulness of the para-apical technique, a study was performed in 50 normal subjects as well as in 16 patients with dilated cardiomyopathy. In all patients, standard views and the new para-apical view were performed. In five cases, contrast echocardiography of the heart was performed to verify the right-heart anatomy. In five patients, computer-tomography of the heart was performed to see the position of the right-heart chambers in the chest and to evaluate the new para-apical ultrasound window. The standard values for the right ventricle in the control group were (in mean values): diastolic diameter, 28.61 +/- 3.19 mm; systolic diameter, 19.10 +/- 2.40 mm; free wall thickness, 4.46 +/- 1.06 mm and shortening fraction, 32.42% +/- 4.02%. The examined parameters in patients with dilated cardiomyopathy were: diastolic diameter, mean value 38.63 +/- 5.80 mm; systolic diameter, mean value 32.48 +/- 4.96 mm; free wall thickness, mean value 8.70 +/- 1.05 mm and shortening fraction, mean value 15.96 +/- 4.02%.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3439250

  10. 管道钢管壁厚超声波检测技术%Ultrasonic Testing Technology for Wall Thickness of Steel Pipe Used for Pipeline

    Institute of Scientific and Technical Information of China (English)

    方伟; 罗华权; 何跃

    2015-01-01

    针对油气输送管道长时间生产运行中的腐蚀造成的管道钢管壁厚逐渐减薄甚至穿孔现象,采用超声测厚技术在不损坏管道的情况下,可实现准确测量管道壁厚,并发现管道内部缺陷。介绍了钢管超声测厚技术的原理、超声测厚装置的选择、超声测厚方法及其操作步骤,分析了钢管超声测厚的影响因素,并对钢管测厚过程中出现的问题给出了处理办法。钢管超声测厚技术具有无损管道且测量精度高的特点,还可用于油井管壁厚的检测。%The wall thickness of steel pipe used for pipeline is thinning until perforated due to corrosion after the pipeline has operated for a long time. Using ultrasonic thickness measurement technology under the condition of no damage to pipeline, which can realize accurate measurement for pipe wall thickness, and found the pipe internal defects. In this article, the principle of ultrasonic thickness testing technology, selection of ultrasonic thickness testing devices, method and operating steps were introduced. The main influence factors of ultrasonic thickness measurement technology were analyzed, and the disposition method for problems occurred in the process of thickness testing were provided.

  11. The subpetrous carotid wall hematoma. A sign of spontaneous dissection of the internal carotid artery on non-enhanced computed tomography. A retrospective study

    Energy Technology Data Exchange (ETDEWEB)

    Jensen-Kondering, U. [Univ. Hospital Schleswig-Holstein, Kiel (Germany). Dept. of Radiology and Neuroradiology; Univ. Hospital Schleswig-Holstein, Kiel (Germany). Dept. of Neurology; Huhndorf, M.; Madjidyar, J.; Jansen, O. [Univ. Hospital Schleswig-Holstein, Kiel (Germany). Dept. of Radiology and Neuroradiology

    2015-03-15

    Spontaneous dissection of the internal carotid artery (CAD) is an increasingly recognized cause for stroke especially in young and middle-aged patients. We hypothesized that non-enhanced cranial computed tomography (NECCT) can visualize the subpetrous carotid wall hematoma and thus enable identification of patients with CAD. We retrospectively reviewed patients with confirmed CAD (n=21) and a control group with ischemic symptoms but without CAD (n=42) who received NECCT at admission. Two independent neuroradiologists rated the presence and shape of SPH, density and diameter of the subpetrous internal carotid artery. Additionally, we correlated the shape of the subpetrous carotid wall hematoma with the grade of stenosis on subsequent angiographic imaging. The subpetrous carotid wall hematoma was present in 14 of 21 patients (Cohen's k = 0.67). Mean diameter was 6.95 ± 1.05 mm in dissected vessels and 5.71 ± 1.52 mm in the contralateral vessel (p<0.05). Mean difference in vessel density was 15.05 ± 8.01 HU (p<0.01). Median grade of stenosis was significantly higher in patients with a full moon- shaped (n=11) than crescent-shaped (n=3) subpetrous carotid wall hematoma (21% vs. 80%, p<0.05). Two-thirds of patients with CAD were correctly identified on NECCT. The extracranial carotid artery should be evaluated in patients with symptoms of cerebral ischemia.

  12. Estimation of the bi-dimensional motion of the arterial wall in ultrasound imaging with a combined approach of segmentation and speckle tracking

    OpenAIRE

    Zahnd, Guillaume

    2012-01-01

    This thesis is focused on the domain of bio-medical image processing. The aim of our study is to assess in vivo the parameters traducing the mechanical properties of the carotid artery in ultrasound imaging, for early detection of cardiovascular diseases. The analysis of the longitudinal motion of the arterial wall tissues, i.e. in the same direction as the blood flow, represents the principal motivation of this work. The three main contributions proposed in this work are i) the development o...

  13. Randomised comparison of the effects of nicardipine and esmolol on coronary artery wall stress: implications for the risk of plaque rupture

    OpenAIRE

    Williams, M.; Low, C.; Wilkins, G; Stewart, R

    2000-01-01

    OBJECTIVE—To determine whether the β blocker esmolol reduces coronary artery wall stress more than the short acting dihydropyridine calcium antagonist nicardipine.
DESIGN—Randomised double blind placebo controlled trial.
SETTING—Tertiary cardiology centre.
PATIENTS—Patients with coronary artery disease.
INTERVENTIONS—20 patients were randomised double blind to an infusion of nicardipine (n = 10) or esmolol (n = 10) titrated to reduce systolic blood pressure by 20 mm Hg.
MAIN OUTCOME MEASURES—...

  14. Comparison of characteristics parameters in the evaluation of wall thickness diminishing in admiralty brass tubes of the steam condenser, tested by eddy currents

    International Nuclear Information System (INIS)

    This work is aimed to appraise the measure of the wall thickness diminishing in the signals evaluation obtained in the inspection of steam condenser by eddy currents. In the analysis of the obtained signals were observed in the brass tubes a great quantity of internal defects whose signal indicates that there were diminishing of the wall thickness between 80% and 100%. With all this information and analyzing the data acquired, the tubes with more important indications were selected to make a more exhaustive study of the found defectology. As first test, it was measured the thickness of the worn tubes, comparing them with the original ones that are in stock. It was verified that the tubes separated for this study presented a 30% less thickness in comparison with the new tubes. A semiquantitative chemical test (EDAX) was made to verify if it was the same material. One of the extracted tubes (066 Y1) was reinspected in order to isolate the area with indications. Once this was performed, it was decided to cut the tube to make a visual inspection and to evaluate to what type of defect corresponds to the signals obtained. In the metallography it was confirm that it was a horseshoe type defect. When performing a dimensional control test of the found real defect, it was checked that the information obtained by eddy currents regarding the diminishing of the wall thickness diminishing was valid. At a last stage of the test, it was proceed to make an study and verification of the used parameters, probes, standards and finally determine which shall be the convenient modifications to minimize errors. (author)

  15. Manual and automated intima-media thickness and diameter measurements of the common carotid artery in patients with renal failure disease.

    Science.gov (United States)

    Loizou, Christos P; Kasparis, Takis; Lazarou, Theodoros; Pattichis, Constandinos S; Pantziaris, Marios

    2014-10-01

    The objective of this study was to investigate differences in intima-media thickness (IMT) and diameter (D) measurements of the common carotid artery (CCA) in ultrasound imaging in normal subjects and renal failure disease (RFD) patients. Manual measurements by two experts and automated segmentation measurements (based on snakes and active contour models (ACM)) were carried out on 73 normal subjects, and 80 RFD patients. Statistical analysis was carried out using the Wilcoxon rank-sum test at psegmentation was slightly more accurate than segmentation based on snakes. Further work is needed to validate these findings on a larger group of subjects. PMID:25173810

  16. Model experimental research on deformation and subsidence characteristics of ground and wall rock due to mining under thick overlying terrane

    Energy Technology Data Exchange (ETDEWEB)

    Weizhong Ren; Chengmai Guo; Ziqiang Peng; Yonggang Wang [Chinese Academy of Sciences, Wuhan (China). Institute of Rock and Soil Mechanics

    2010-06-15

    Based on the prototype of a mine, a physical simulation test is conducted. The characteristics of the deformation and failure of the ground surface and the wall rock around a goaf, as well as the creep behavior of the wall rock deformation and the failure mechanism, are analyzed. The simulation test has greatly improved our understanding on the wall rock's deformation and failure characteristics. For the first time, digital close-range photogrammetry was used to measure the displacements in a sectional model test. The measurements by this technique agreed very well with those obtained by other methods, such as using dial gauges.

  17. 薄壁铜管壁厚控制的超声检测系统%Ultrasonic Testing System for Thickness Control of Thin-walled Copper Tube

    Institute of Scientific and Technical Information of China (English)

    袁肖肖; 刘晴岩

    2011-01-01

    设计超声检测系统,对薄壁铜管的壁厚均匀性进行检测,用分析处理后的检测结果,作为壁厚控制的调整参数.结果表明,采用该系统获得的调整参数,精度达到0.lmm,保证了薄壁铜管壁厚控制的精确性.%To test the even degree of thickness for thin-walled copper tube by the ultrasonic testing system, we obtained the adjusting parameter of thickness control depend on the worked result of inspection. The outcomes indicate that the precision of the adjusting parameter is 0. 1mm, and this system could ensure the accuracy of thickness control.

  18. wall

    Directory of Open Access Journals (Sweden)

    Irshad Kashif

    2016-01-01

    Full Text Available Maintaining indoor climatic conditions of buildings compatible with the occupant comfort by consuming minimum energy, especially in a tropical climate becomes a challenging problem for researchers. This paper aims to investigate this problem by evaluating the effect of different kind of Photovoltaic Trombe wall system (PV-TW on thermal comfort, energy consumption and CO2 emission. A detailed simulation model of a single room building integrated with PV-TW was modelled using TRNSYS software. Results show that 14-35% PMV index and 26-38% PPD index reduces as system shifted from SPV-TW to DGPV-TW as compared to normal buildings. Thermal comfort indexes (PMV and PPD lie in the recommended range of ASHARE for both DPV-TW and DGPV-TW except for the few months when RH%, solar radiation intensity and ambient temperature were high. Moreover PVTW system significantly reduces energy consumption and CO2 emission of the building and also 2-4.8 °C of temperature differences between indoor and outdoor climate of building was examined.

  19. Reduction of internal carotid artery intima-media thickness in patients with moderate-to-severe obstructive sleep apnea syndrome after nasal surgery and uvulopalatopharyngoplasty.

    Science.gov (United States)

    Peng, Yikun; Zhang, Liangchun; Hu, Defeng; Dai, Yubing; Wang, Shuhui; Liao, Hongyong; Xiong, Yan

    2016-05-01

    Conclusion Multi-level surgeries for the nasal cavity and palate can reduce the severity of obstructive sleep apnea with major narrowing above the retropalatal airway and reduce the carotid intima-media thickness, which can provide cardiovascular benefits to patients. Objective To evaluate the outcomes of moderate-to-severe obstructive sleep apnea syndrome by surgeries and the change of internal carotid artery intima-media thickness after surgeries. Subjects and methods Sixty-four patients with obstructive sleep apnea, narrowing at the nasal cavity, and retropalatal airways were enrolled in this study. Fifty-two patients underwent nasal surgery and modified uvulopalatopharyngoplasty. Twelve patients who refused surgeries and continuous positive airway pressure treatment received only conservative treatment. All patients were evaluated within 1 month before and 6 months after treatment using polysomnography, upper airway endoscopy, and B mode ultrasound. Results The success rate was 61.5% (32/52 patients) in the surgery group. There were significant differences between the surgery group and non-surgery group 6 months after treatment in the apnea hypopnea index, minimum and mean oxygen saturation, blood pressure, triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and internal Carotid intima-media thickness. The changes in the oxygen saturation and the apnea hypopnea index showed significant correlations with the changes in the intima-media thickness. PMID:26824298

  20. Plasma levels of the arterial wall protein fibulin-1 are associated with carotid-femoral pulse wave velocity

    DEFF Research Database (Denmark)

    Laugesen, Esben; Høyem, Pernille; Christiansen, Jens Sandahl;

    2013-01-01

    The arterial system in diabetic patients is characterized by generalized non-atherosclerotic alterations in the vascular extracellular matrix causing increased arterial stiffness compared with subjects without diabetes. The underlying pathophysiology remains elusive. The elastin-associated extrac......The arterial system in diabetic patients is characterized by generalized non-atherosclerotic alterations in the vascular extracellular matrix causing increased arterial stiffness compared with subjects without diabetes. The underlying pathophysiology remains elusive. The elastin...... stiffness. Whether plasma fibulin-1 is associated with arterial stiffness at earlier phases of type 2 diabetes has not been determined....