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Sample records for experimentally measured arterial

  1. A theoretical and non-destructive experimental approach for direct inclusion of measured collagen orientation and recruitment into mechanical models of the artery wall.

    Science.gov (United States)

    Hill, Michael R; Duan, Xinjie; Gibson, Gregory A; Watkins, Simon; Robertson, Anne M

    2012-03-15

    Gradual collagen recruitment has been hypothesized as the underlying mechanism for the mechanical stiffening with increasing stress in arteries. In this work, we investigated this hypothesis in eight rabbit carotid arteries by directly measuring the distribution of collagen recruitment stretch under increasing circumferential loading using a custom uniaxial (UA) extension device combined with a multi-photon microscope (MPM). This approach allowed simultaneous mechanical testing and imaging of collagen fibers without traditional destructive fixation methods. Fiber recruitment was quantified from 3D rendered MPM images, and fiber orientation was measured in projected stacks of images. Collagen recruitment was observed to initiate at a finite strain, corresponding to a sharp increase in the measured mechanical stiffness, confirming the previous hypothesis and motivating the development of a new constitutive model to capture this response. Previous constitutive equations for the arterial wall have modeled the collagen contribution with either abrupt recruitment at zero strain, abrupt recruitment at finite strain or as gradual recruitment beginning at infinitesimal strain. Based on our experimental data, a new combined constitutive model was presented in which fiber recruitment begins at a finite strain with activation stretch represented by a probability distribution function. By directly including this recruitment data, the collagen contribution was modeled using a simple Neo-Hookean equation. As a result, only two phenomenological material constants were required from the fit to the stress stretch data. Three other models for the arterial wall were then compared with these results. The approach taken here was successful in combining stress-strain analysis with simultaneous microstructural imaging of collagen recruitment and orientation, providing a new approach by which underlying fiber architecture may be quantified and included in constitutive equations. Copyright

  2. Experimental and numerical studies of two arterial wall delamination modes.

    Science.gov (United States)

    Leng, Xiaochang; Zhou, Boran; Deng, Xiaomin; Davis, Lindsey; Lessner, Susan M; Sutton, Michael A; Shazly, Tarek

    2017-09-19

    Arterial wall dissection, which results from various pathophysiological processes, can lead to the occurrence of large area delamination in the aortic wall that can potentially block blood flow and lead to deleterious clinical conditions. Despite its critical clinical relevance, few studies have focused on investigating the failure mode of delamination in the arterial wall. In this study, we quantify the energy release rate of the medial layer of a porcine abdominal aorta via two delamination experiments: the mixed-mode delamination experiment and the "T"-shaped delamination experiment. A cohesive zone model (CZM) is applied to simulate the arterial wall delamination and Holzapfel-Gasser-Ogden (HGO) material model is used to capture the bulk arterial material behavior. A set of parameter values for the HGO and CZM models are identified through matching simulation predictions of the load vs. load-point displacement curve with experimental measurements. Then the parameter values and critical energy release rates obtained from experiments are used as input data for simulation predictions for two arterial wall delamination experiments. The simulation predictions show that the delamination front matches well with experimental measurements. Moreover, the mixed-mode delamination experiment reveals a shear mode-dominated failure event, whereas the "T"-shaped delamination experiment is an opening failure process. The integration of experimental data and numerical predictions of arterial delamination events provides a comprehensive description of distinct failure modes and aids in the prediction of aortic dissection. Copyright © 2017. Published by Elsevier Ltd.

  3. Flow measurements in the major visceral arteries

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    Schroeder, J.; Gerhardt, P.; Terwey, B.; Krastel, A.

    1982-02-01

    Arterial flow was measured by the spill-over technique in 202 coeliac arteries and 158 superior mesenteric arteries during the course of visceral angiography in 250 patients. In the coeliac artery a mean value of 15.8 +- 4.3 ml/sec was obtained, flow in the super mesenteric artery was significantly less at 12.1 +- 3.4 ml/sec. The wide variation from 4 to 26 ml/sec in the coeliac artery was remarkable, as well as flows from six to 20 ml/sec in the superior mesenteric artery.

  4. Arterial endothelial function measurement method and apparatus

    Science.gov (United States)

    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.

  5. Temperature measurement methods during direct heat arterial tissue fusion.

    Science.gov (United States)

    Cezo, James D; Kramer, Eric; Taylor, Kenneth D; Ferguson, Virginia; Rentschler, Mark E

    2013-09-01

    Fusion of biological tissues through direct and indirect heating is a growing area of medical research, yet there are still major gaps in understanding this procedure. Several companies have developed devices which fuse blood vessels, but little is known about the tissue's response to the stimuli. The need for accurate measurements of tissue behavior during tissue fusion is essential for the continued development and improvement of energy delivery devices. An experimental study was performed to measure the temperatures experienced during tissue fusion and the resulting burst pressure of the fused arteries. An array of thermocouples was placed in the lumen of a porcine splenic artery segment and sealed using a ConMed Altrus thermal fusion device. The temperatures within the tissue, in the device, and at the tissue-device interface were recorded. These measurements were then analyzed to calculate the temperature profile in the lumen of the artery. The temperature in the artery at the site of tissue fusion was measured to range from 142 to 163 °C using the ConMed Altrus. The corresponding burst pressure for arteries fused at this temperature was measured as 416 ± 79 mmHg. This study represents the first known experimental measurement of temperature at the site of vessel sealing found in the literature.

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

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    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.

  7. Experimental model for creation of carotid artery aneurysms in dogs

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    Kim, Sung Hyun; Han, Moon Hee; Yu, In Kyu; Lee, Sang Hyun; Chang, Kee Hyun [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

    1996-11-01

    To describe the detailed technique for producing experimental carotid aneurysms in dogs and the success rate, cause of failure and remedy, based on our experience. Fourteen male dogs weighing 12-15kg were anesthetized with inhalation of 1-2% halothane and 50% nitrous oxide. Each surgical procedure was performed under sterile condition with the aid of an operating microscope. A paramidline incision 7-8cm in length was made parallel to and medial to the external jugular vein in the dog's neck. The external jugular vein was harvested as a 1cm vein pouch by ligation and division of the proximal and distal ends. The ipsilateral common carotid artery was exposed and clamped at both ends by a vascular clamp. A 5-mm long elliptical arteriotomy was made at the mid portion of the artery, and then end to side anastomosis between the artery and vein sac was performed by using interrupted 7-0 monofilament prolene sutures. Carotid arteriography or Doppler sonography was performed 1-6 weeks after aneurysm construction. Twenty experimental aneurysms were constructed, and 17 aneurysms were patent on follow up study, but one dog with two aneurysms died from hemorrhagic pneumonia 17 days after surgery. The overall patency rate was 75%. We demonstrated the feasibility of creating experimental aneurysm models in the dog and expect that the technique presented will help to avoid failure in the construction of aneurysms.

  8. Development of an Experimental and Digital Cardiovascular Arterial Model for Transient Hemodynamic and Postural Change Studies: "A Preliminary Framework Analysis".

    Science.gov (United States)

    Hewlin, Rodward L; Kizito, John P

    2017-11-09

    The ultimate goal of the present work is to aid in the development of tools to assist in the treatment of cardiovascular disease. Gaining an understanding of hemodynamic parameters for medical implants allow clinicians to have some patient-specific proposals for intervention planning. In the present work an experimental and digital computational fluid dynamics (CFD) arterial model consisting of a number of major arteries (aorta, carotid bifurcation, cranial, femoral, jejunal, and subclavian arteries) were fabricated to study: (1) the effects of local hemodynamics (flow parameters) on global hemodynamics (2) the effects of transition from bedrest to upright position (postural change) on hemodynamics, and (3) diffusion of dye (medical drug diffusion simulation) in the arterial system via experimental and numerical techniques. The experimental and digital arterial models used in the present study are the first 3-D systems reported in literature to incorporate the major arterial vessels that deliver blood from the heart to the cranial and femoral arteries. These models are also the first reported in literature to be used for flow parameter assessment via medical drug delivery and orthostatic postural change studies. The present work addresses the design of the experimental and digital arterial model in addition to the design of measuring tools used to measure hemodynamic parameters. The experimental and digital arterial model analyzed in the present study was developed from patient specific computed tomography angiography (CTA) scans and simplified geometric data. Segments such as the aorta (ascending and descending) and carotid bifurcation arteries of the experimental and digital arterial model was created from online available patient-specific CTA scan data provided by Charite' Clinical and Research Hospital. The cranial and coronary arteries were simplified arterial geometries developed from dimensional specification data used in previous work. For the patient

  9. Femoral artery pressure measurement to predict the outcome of arterial surgery in patients with multilevel disease

    DEFF Research Database (Denmark)

    Faris, I; Tønnesen, K H; Agerskov, K

    1982-01-01

    Direct measurement of the femoral artery pressure before operation has been used to predict the postoperative change in ankle and toe pressure in 102 limbs (83 patients) that underwent aortoiliac surgery for the treatment of atherosclerotic occlusion or stenosis affecting both the aortoiliac...... 25 mm Hg was associated with a high probability that amputation would be required. The chances of an amputation were less than 3% if a toe pressure higher than 40 mm Hg was predicted. If the predicted ankle pressure index was lower than 0.56, there was a 90% chance that intermittent claudication...... would persist. Measurement of the femoral artery pressure allows prediction of the toe and ankle pressure response to surgery to be made with sufficient accuracy to permit a preoperative decision to be made between the need for a single-level or a two-level arterial reconstruction: no patients who had...

  10. Arterial pressure measurement: Is the envelope curve of the oscillometric method influenced by arterial stiffness?

    Energy Technology Data Exchange (ETDEWEB)

    Gelido, G [Electronic department, Universidad Tecnologica Nacional FRBA, Bs. As. (Argentina); Angiletta, S [Electronic department, Universidad Tecnologica Nacional FRBA, Bs. As. (Argentina); Pujalte, A [Electronic department, Universidad Tecnologica Nacional FRBA, Bs. As. (Argentina); Quiroga, P [Electronic department, Universidad Favaloro FICEN, Bs. As. (Argentina); Cornes, P [Electronic department, Universidad Favaloro FICEN, Bs. As. (Argentina); Craiem, D [Electronic department, Universidad Favaloro FICEN, Bs. As. (Argentina)

    2007-11-15

    Measurement of peripheral arterial pressure using the oscillometric method is commonly used by professionals as well as by patients in their homes. This non invasive automatic method is fast, efficient and the required equipment is affordable with a low cost. The measurement method consists of obtaining parameters from a calibrated decreasing curve that is modulated by heart beats witch appear when arterial pressure reaches the cuff pressure. Diastolic, mean and systolic pressures are obtained calculating particular instants from the heart beats envelope curve. In this article we analyze the envelope of this amplified curve to find out if its morphology is related to arterial stiffness in patients. We found, in 33 volunteers, that the envelope waveform width correlates to systolic pressure (r=0.4, p<0.05), to pulse pressure (r=0.6, p<0.05) and to pulse pressure normalized to systolic pressure (r=0.6, p<0.05). We believe that the morphology of the heart beats envelope curve obtained with the oscillometric method for peripheral pressure measurement depends on arterial stiffness and can be used to enhance pressure measurements.

  11. [Beneficial effects of renal denervation on pulmonary vascular remodeling in experimental pulmonary artery hypertension].

    Science.gov (United States)

    Zhang, Shujuan; Zhao, Qingyan; Jiang, Xuejun; Yang, Bo; Dai, Zixuan; Wang, Xiaozhan; Wang, Xule; Guo, Zongwen; Yu, Shengbo; Tang, Yanhong; Hu, Wei; Huang, Congxin

    2015-04-14

    To explore the effects of renal sympathetic denervation (RSD) on pulmonary vascular remodeling in a model of pulmonary arterial hypertension (PAH). According to the random number table, 24 beagles were randomized into control, PAH and PAH+RSD groups (n=8 each). The levels of neurohormone, echocardiogram and dynamics parameters were measured. Then 0.1 ml/kg dimethylformamide (control group) or 2 mg/kg dehydromonocrotaline (PAH and PAH+RSD groups) were injected. The PAH+RSD group underwent RSD after injection. At week 8 post-injection, the neurohormone levels, echocardiogram, dynamics parameters and pulmonary tissue morphology were observed. The values of right ventricular systolic pressure (RVSP) and pulmonary arterial systolic pressure (PASP) in PAH and PAH+RSD groups were both significantly higher than those in control group ((42.8±8.7), (30.8±6.8) vs (23.2±5.7) mmHg (1 mmHg=0.133 kPa) and (45.1±11.2), (32.6±7.9) vs (24.7±7.1) mmHg). Meanwhile, the values of RVSP and PASP in PAH group were higher than those in PAH+RSD group (all PRSD group ((46±8) and (67±9) pg/ml) (all PRSD dogs. RSD suppresses pulmonary vascular remodeling and decreases pulmonary arterial pressure in experimental PAH. And the effect of RSD on PAH may contribute to decreased neurohormone levels.

  12. Reconstruction of brachial artery pressure from noninvasive finger pressure measurements

    NARCIS (Netherlands)

    Bos, W. J.; van Goudoever, J.; van Montfrans, G. A.; van den Meiracker, A. H.; Wesseling, K. H.

    1996-01-01

    Pulse wave distortions, mainly caused by reflections, and pressure gradients, caused by flow in the resistive vascular tree, may cause differences between finger and brachial artery pressures. These differences may limit the use of finger pressure measurements. We investigated whether brachial

  13. Radial artery cannulation decreases the distal arterial blood flow measured by power Doppler ultrasound.

    Science.gov (United States)

    Numaguchi, Atsushi; Adachi, Yushi U; Aoki, Yoshitaka; Ishii, Yasuhiro; Suzuki, Katsumi; Obata, Yukako; Sato, Shigehito; Nishiwaki, Kimitoshi; Matsuda, Naoyuki

    2015-10-01

    Radial arterial cannulation is a popular technique for continuous hemodynamic monitoring in an area of anesthesia and intensive care. Although the risk for invasive monitoring is considerable, there is scarce information about the change in blood flow of cannulated vessel after the catheterization. In the current investigation, we evaluated the change in the cannulated arterial blood flow. Six volunteers (study 1) and eight post-surgical patients (study 2) were enrolled into the studies. In the study 1, the both side of diameter of radial artery (RA), ulnar artery (UA) and dorsal branch of radial artery (DBRA) of participants were measured using power Doppler ultrasound (PDU) with or without proximal oppression. In the study 2, the diameter of RA, UA and DBRA of the both intact and cannulated side were compared. Study 1: The diameter of RA was 3.4 (0.52) [mean (SD)] mm and the proximal oppression significantly decreased the diameter to 1.8 (0.59) mm. The diameter of DBRA measured by PDU also decreased 2.0 (0.60)-1.3 (0.59) mm. Study 2: There was no difference between the diameters of right and left RA, however, the UA was larger [3.4 (0.60) vs. 2.8 (0.83) mm] and the DBRA was narrower [1.4 (0.43) vs. 2.0 (0.47) mm] in the cannulated side. The diameters of DBRA were different between the intact and cannulated side in the patients. Although there is no information of relationships between cause of severe complication and decreased flow, significant reduction of blood flow should be concerned.

  14. Continuous cardiac output measurement: arterial pressure analysis versus thermodilution technique during cardiac surgery with cardiopulmonary bypass

    NARCIS (Netherlands)

    Lorsomradee, S.; Lorsomradee, S. R.; Cromheecke, S.; de Hert, S. G.

    2007-01-01

    This study compared cardiac output measured with an arterial pressure-based cardiac output measurement system and a thermodilution cardiac output measurement system. We studied 36 patients undergoing cardiac surgery with cardiopulmonary bypass. Simultaneous arterial pressure-based and thermodilution

  15. Evaluation of the effects of intra-arterial sugammadex and dexmedetomidine: an experimental study

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    Volkan Hancı

    Full Text Available Abstract Background: Intra-arterial injection of medications may cause acute and severe ischemia and result in morbidity and mortality. There is no information in the literature evaluating the arterial endothelial effects of sugammadex and dexmedetomidine. The hypothesis of our study is that sugammadex and dexmedetomidine will cause histological changes in arterial endothelial structure when administered intra-arterially. Methods: Rabbits were randomly divided into 4 groups. Group Control (n = 7; no intervention performed. Group Catheter (n = 7; a cannula inserted in the central artery of the ear, no medication was administered. Group Sugammadex (n = 7; rabbits were given 4 mg/kg sugammadex into the central artery of the ear, and Group Dexmedetomidine (n = 7; rabbits were given 1 µg/kg dexmedetomidine into the central artery of the ear. After 72 h, the ears were amputated and histologically investigated. Results: There was no significant difference found between the control and catheter groups in histological scores. The endothelial damage, elastic membrane and elastic fiber damage, smooth muscle hypertrophy and connective tissue increase scores in the dexmedetomidine and sugammadex groups were significantly higher than both the control and the catheter groups (p < 0.05. There was no significant difference found between the dexmedetomidine and sugammadex groups in histological scores. Conclusion: Administration of sugammadex and dexmedetomidine to rabbits by intra-arterial routes caused histological arterial damage. To understand the histological changes caused by sugammadex and dexmedetomidine more clearly, more experimental research is needed.

  16. Monitoring Personalized Trait Using Oscillometric Arterial Blood Pressure Measurements

    OpenAIRE

    Young-Suk Shin

    2012-01-01

    The blood pressure patterns obtained from a linearly or stepwise deflating cuff exhibit personalized traits, such as fairly uniform peak patterns and regular beat geometry; it can support the diagnosis and monitoring of hypertensive patients with reduced sensitivity to fluctuations in Blood Pressure (BP) over time. Monitoring of personalized trait in Oscillometric Arterial Blood Pressure Measurements (OABPM) uses the Linear Discriminant Analysis (LDA) algorithm. The representation of personal...

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

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    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.

  18. Experimental Joint Quantum Measurements with Minimum Uncertainty

    Science.gov (United States)

    Ringbauer, Martin; Biggerstaff, Devon N.; Broome, Matthew A.; Fedrizzi, Alessandro; Branciard, Cyril; White, Andrew G.

    2014-01-01

    Quantum physics constrains the accuracy of joint measurements of incompatible observables. Here we test tight measurement-uncertainty relations using single photons. We implement two independent, idealized uncertainty-estimation methods, the three-state method and the weak-measurement method, and adapt them to realistic experimental conditions. Exceptional quantum state fidelities of up to 0.999 98(6) allow us to verge upon the fundamental limits of measurement uncertainty.

  19. Monitoring Personalized Trait Using Oscillometric Arterial Blood Pressure Measurements

    Directory of Open Access Journals (Sweden)

    Young-Suk Shin

    2012-01-01

    Full Text Available The blood pressure patterns obtained from a linearly or stepwise deflating cuff exhibit personalized traits, such as fairly uniform peak patterns and regular beat geometry; it can support the diagnosis and monitoring of hypertensive patients with reduced sensitivity to fluctuations in Blood Pressure (BP over time. Monitoring of personalized trait in Oscillometric Arterial Blood Pressure Measurements (OABPM uses the Linear Discriminant Analysis (LDA algorithm. The representation of personalized traits with features from the oscillometric waveforms using LDA algorithm includes four phases. Data collection consists of blood pressure data using auscultatory measurements and pressure oscillations data obtained from the oscillometric method. Preprocessing involves the normalization of various sized oscillometric waveforms to a uniform size. Feature extraction involves the use of features from oscillometric amplitudes, and trait identification involves the use of the LDA algorithm. In this paper, it presents a novel OABPM-based blood pressure monitoring system that can monitor personalized blood pressure pattern. Our approach can reduce sensitivity to fluctuations in blood pressure with the features extracted from the whole area in oscillometric arterial blood pressure measurement. Therefore this technique offers reliable blood pressure patterns. This study provides a cornerstone for the diagnosis and management of hypertension in the foreseeable future.

  20. Long-term facial artery catheter implantation for serial arterial blood sampling and invasive arterial blood pressure measurement in horses.

    Science.gov (United States)

    Dias, Deborah Penteado Martins; Teixeira, Luisa Gouvêa; Canola, Paulo Aléscio; Albernaz, Raquel Mincarelli; Marques, José Antônio; Neto, José Corrêa de Lacerda

    2012-06-01

    The purpose of this investigation was to evaluate surgical catheter implantation in the facial artery of horses and the long-term maintenance of such arteries using heparin and ascorbic acid as filling solution. Nine horses were implanted with a polyurethane catheter. The catheters were flushed with a heparin/ascorbic acid solution every 8h and remained patent for 25 days. Arterial blood samples were collected twice a day, and one exercise test that included serial blood samples and arterial pressure recordings was performed on a treadmill. Polyurethane catheters surgically implanted in the facial artery can be kept patent by filling with a heparin/ascorbic acid solution and provide convenient invasive arterial access in horses which is suitable for use for serial blood sampling and blood pressure recordings, even during exercise on treadmill. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Evaluation of arterial impairment after experimental gelatin sponge embolization in a rabbit renal model

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    Oh, Jung Suk; Lee, Hae Gi; Chun, Ho Jong; Choi, Byung Gil; Choi, Yeong Jin [Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of)

    2015-02-15

    Arterial stenosis is a major obstacle for subsequent interventional procedures. We hypothesized that the stenosis is caused by gelatin sponge embolization and performed an experimental study in a rabbit renal model. A total of 24 rabbits were embolized with porcine gelatin sponge particles injected into the renal arteries. Four rabbits were sacrificed on 1 day, 4 days, 1 week, 2 weeks, 3 weeks, and 4 weeks after embolization. Microscopic evaluations were performed on hematoxylin-eosin and smooth muscle actin immunohistochemical stained sections. Gelatin sponge particles were mainly observed in the segmental and interlobar arteries. Transmural inflammation of the embolized arterial wall and mild thickening of the media were observed 1 week after embolization. Resorption of the gelatin sponge and organization of thrombus accompanied by foreign body reactions, were observed from 2 to 4 weeks after embolization. Microscopic images of the 3 weeks group showed vessel lumens filled mostly with organized thrombi, resulting in severe stenosis. Additionally, vessels showed a thickened intima that contained migrating smooth muscle cells and accompanying interruption of the internal elastic lamina. The migrating smooth muscle cells were distributed around the recanalized arterial lumen. Gelatin sponge embolization may induce arterial stenosis by causing organized thrombus and intimal hyperplasia, which consists of migrating smooth muscle cells and intimal collagen deposits.

  2. Development of a tonometric sensor for measurement and recording of arterial pressure waveform

    Science.gov (United States)

    Tomczuk, K.; Werszko, M.; Sasiadek, J. Z.; Kosek, J.; Berny, W.; Weiser, A.; Feder-Kubis, J.

    2013-09-01

    There are many techniques and devices for measurement and recording of arterial blood pressure. Some of them allow (enable) additionally to observe the shape of a wave of arterial pressure, which can be regarded as one of the most important diagnostic parameters of human cardiovascular system. This paper presents a novel design and prototype of a new, non-invasive blood waveform measuring device. It expounds theoretical and experimental (including latest preliminary clinical) results obtained during several years of extensive investigations into blood pressure waveform measuring and monitoring problem. According to investigations performed in the laboratory and preliminary clinical evaluation, the sensor has linear steady-state characteristics and satisfactory dynamic properties. It is an efficient and accurate tool for blood pressure waveform monitoring and assessing the cardiovascular condition of the patients. The novelty of this solution is that the device is equipped with a pneumatic pressure sensor based on the pneumatic nozzle flapper amplifier principle with negative feedback. Due to such a technical solution, the device does not require any cuff, which remains an essential component of the majority of contemporary non-invasive blood pressure measurement devices; therefore, it can be used on the artery where the application of a cuff would be impossible (e.g., carotid artery). This advantage makes possible to obtain an accurate shape of blood pressure waveform with high fidelity, comparable to a direct measurement method. Moreover, during the measurement the device converts directly "pressure into pressure." Such a principle of operation makes possible to eliminate additional calibration (at the current stage of research we have eliminated the necessity of calibration in laboratory conditions).

  3. Endovascular treatment of peripheral arterial injury with covered stents: an experimental study in pigs

    Directory of Open Access Journals (Sweden)

    Sergio Belczak

    2011-01-01

    Full Text Available OBJECTIVE: To evaluate the feasibility of using endovascular repair to treat penetrating arterial injuries with covered stents. Feasibility was examined according to the circumferential extent of the injury. INTRODUCTION: Surgical trauma often increases the risk of major morbidity and mortality associated with vascular injury, and endovascular repair has many advantages in such situations. METHODS: Twenty white male domestic pigs weighing 28-38 kg with controlled vascular injuries were divided into four equal groups according to the circumferential extent of their vascular lesion (i.e., no lesion, lesion 50%, and complete lesion. The left common carotid artery was dissected with proximal and distal control, and this procedure was followed by controlled sectioning of the arterial wall. Local manual compression was applied for 10 min and was followed by endovascular repair with the placement of a 5x50 mm VIABHAN TM covered stent using the femoral approach. We also monitored additional variables, such as the duration of the procedures (the mean was 56.3 ± 19.1 min, ultrasound parameters (e.g., maximum arterial diameter, peak systolic and diastolic velocity, and resistance index, arteriography findings, and fluctuations in vital signs (e.g., cardiac output, arterial pressure, and central venous pressure. RESULTS: The experimental procedure was found to be feasible and reproducible. Repairs were successful in all animals in the control (no lesion and 50% group and in one pig in the complete lesion group. DISCUSSION: The endovascular repair of an arterial injury is possible, but success depends on the circumferential extent of the arterial lesion. The present experimental model, which involved endovascular techniques, highlighted important factors that must be considered in future studies involving similar animals and materials.

  4. Oscillometric blood pressure measurements: differences between measured and calculated mean arterial pressure.

    NARCIS (Netherlands)

    Kiers, H.D.; Hofstra, J.M.; Wetzels, J.F.M.

    2008-01-01

    Mean arterial pressure (MAP) is often used as an index of overall blood pressure. In recent years, the use of automated oscillometric blood pressure measurement devices is increasing. These devices directly measure and display MAP; however, MAP is often calculated from systolic blood pressure (SBP)

  5. A finite element model to study the effect of tissue anisotropy on ex vivo arterial shear wave elastography measurements

    Science.gov (United States)

    Shcherbakova, D. A.; Debusschere, N.; Caenen, A.; Iannaccone, F.; Pernot, M.; Swillens, A.; Segers, P.

    2017-07-01

    Shear wave elastography (SWE) is an ultrasound (US) diagnostic method for measuring the stiffness of soft tissues based on generated shear waves (SWs). SWE has been applied to bulk tissues, but in arteries it is still under investigation. Previously performed studies in arteries or arterial phantoms demonstrated the potential of SWE to measure arterial wall stiffness—a relevant marker in prediction of cardiovascular diseases. This study is focused on numerical modelling of SWs in ex vivo equine aortic tissue, yet based on experimental SWE measurements with the tissue dynamically loaded while rotating the US probe to investigate the sensitivity of SWE to the anisotropic structure. A good match with experimental shear wave group speed results was obtained. SWs were sensitive to the orthotropy and nonlinearity of the material. The model also allowed to study the nature of the SWs by performing 2D FFT-based and analytical phase analyses. A good match between numerical group velocities derived using the time-of-flight algorithm and derived from the dispersion curves was found in the cross-sectional and axial arterial views. The complexity of solving analytical equations for nonlinear orthotropic stressed plates was discussed.

  6. Experimental measurement of muon (g-2)

    CERN Document Server

    Gray, F E

    2003-01-01

    The muon (g-2) experiment at Brookhaven National Laboratory has measured the anomalous magnetic moment of the positive muon with a precision of 0.7 ppm. This paper presents that result, concentrating on some of the important experimental issues that arise in extracting the anomalous precession frequency from the data.

  7. Clinicopathological correlation of parapapillary atrophy in monkeys with experimental glaucoma and temporary central retinal artery occlusion

    Directory of Open Access Journals (Sweden)

    Jost B Jonas

    2014-01-01

    Full Text Available Objective: To investigate the clinicopathological correlation of parapapillary atrophy. Materials and Methods: The study included 16 eyes of rhesus monkeys (Macaca mulatta - 4 eyes with experimental glaucoma, 11 eyes after experimental temporary occlusion of the central retinal artery, and 1 normal eye. On histological sections, we measured zones with different histological characteristics.On fundus photographs, alpha zone and beta zone of parapapillary atrophy were measured and correlated with the histological data. Results: The size of the clinical alpha zone of parapapillary atrophy was significantly correlated with the size of the histological region with irregularities of the retinal pigment epithelium (P = 0.05; correlation coefficient r = 0.49 and with the size of the histological region with a decreased density of retinal photoreceptors (P = 0.01; r = 0.60. The size of clinical beta zone of parapapillary atrophy significantly correlated with the size of the histological region with complete loss of the retinal pigment epithelium (P <0.001; r = 0.91, with the size of the histological zone with a complete loss of photoreceptors (P <0.001; r = 0.81, and with the size of the histological zone with a closed choriocapillaris (P <0.001; r = 0.89. Conclusions: The clinically seen alpha zone of parapapillary atrophy correlates with histological parapapillary irregularities of the retinal pigment epithelium and decreased density of retinal photoreceptors. The clinically seen beta zone of parapapillary atrophy correlates with histological complete loss of the retinal pigment epithelium and of the photoreceptors, and a closure of the choriocapillaris.

  8. 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.

  9. EXPERIMENTAL MEASUREMENT OF NANOFLUIDS THERMAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Adnan M. Hussein

    2013-07-01

    Full Text Available Solid particles dispersed in a liquid with sizes no larger than 100nm, known as nanofluids, are used to enhance Thermophysical properties compared to the base fluid. Preparations of alumina (Al2O3, titania (TiO2 and silica (SiO2 in water have been experimentally conducted in volume concentrations ranging between 1 and 2.5%. Thermal conductivity is measured by the hot wire method and viscosity with viscometer equipment. The results of thermal conductivity and viscosity showed an enhancement (0.5–20% and 0.5–60% respectively compared with the base fluid. The data measured agreed with experimental data of other researchers with deviation of less than 5%. The study showed that alumina has the highest thermal conductivity, followed silica and titania, on the other hand silica has the highest viscosity followed alumina and titania.

  10. Experimental and measurement issues in natural radioactivity

    Energy Technology Data Exchange (ETDEWEB)

    Risica, S.; Bochicchio, F.; Bolzan, C.; Grisanti, G.; Nuccetelli, C

    2001-07-01

    The paper deals with some open experimental problems in the field of natural radioactivity. Its aim is to stimulate discussion on the type of research efforts needed in the field and to be planned for the future. The review, which makes no claims to completeness, analyses some issues in gamma spectrometry of natural radionuclides, and the measurement of natural radioactivity in non-nuclear industries and of {sup 222}Rn and {sup 220}Rn concentration in air. (author)

  11. In vivo noninvasive method for measuring local wave velocity in femoral arteries of pig

    Science.gov (United States)

    Zhang, Xiaoming; Kinnick, Randall; Pislaru, Cristina; Fatemi, Mostafa; Greenleaf, James

    2005-09-01

    We have proposed generating a bending wave in the arterial wall using ultrasound radiation force and measuring the wave velocity along the arterial wall [Zhang et al., IEEE Trans. Ultrason. Ferroelectr. Freq. Control 52, 642-652 (2005)]. Here, we report the results of in vivo studies on pigs. The pig was anesthetized, and a micromanometer tip catheter was inserted into the femoral artery to measure luminal pressure. A water bath was created on the animal's groin to allow unimpeded access of the ultrasound beams to the femoral artery. The femoral artery was first located using a 13-MHz linear-array transducer. Then, a vibro-acoustography image was obtained to ensure precise positioning of the excitation force relative to the artery. The artery was excited by the force transducer and the resulting vibration of the arterial wall was measured by a sensing Doppler transceiver. Measured wave velocity was 3.1 m/s at 300 Hz. With this new method wave velocity over a distance of 5 mm, and therefore stiffness of arteries, can be measured locally and non-invasively. Measurement time is short in a few tens of milliseconds, which allows pressure dependence and pharmacological effect on the wall properties to be measured at different cardiac times.

  12. A study on the pathogenesis of equine sesamoiditis: the effects of experimental occlusion of the sesamoidean artery.

    NARCIS (Netherlands)

    Cornelissen, B.P.M.; Rijkenhuizen, A.B.M.; Buma, P.; Barneveld, A.

    2002-01-01

    In this study the potential role of circulatory disturbances in the pathogenesis of sesamoiditis was investigated by studying the clinical and histological effects of experimental occlusion of the sesamoidean artery, which is the main nutrient artery of the proximal sesamoid bone (PSB). For this

  13. Carotid artery exteriorization in brown brocket deer (Mazama gouazoubira) for an experimental study of anesthesia.

    Science.gov (United States)

    Munerato, Marina Salles; Duarte, José Maurício Barbanti; Marques, José Antônio

    2009-09-01

    This report evaluates the carotid artery exteriorization technique to allow repeated percutaneous artery catheterization in six brown brocket deer (Mazama gouazoubira). Repeated percutaneous catheterization of the carotid artery was possible for periods of 3 mo to obtain arterial blood and monitor arterial blood pressure of deer without risk of arterial rupture. The artery pulse was easily palpable for periods up to 15 mo. Postoperative complication and/or arterial damage was not observed.

  14. Experimental measurement of energy harvesting with backpack

    Science.gov (United States)

    Pavelkova, Radka; Vala, David; Suranek, Pavel; Mahdal, Miroslav

    2017-08-01

    This article deals with the energy harvesting systems, especially the energy harvesting backpack, which appears as a convenient means for energy harvesting for mobile sensors power. Before starting the experiment, it was necessary to verify whether this energy will be sufficient to get acquainted with the human kinematics and analyze problematics itself. For this purpose there was used motion capture technology from Xsens. Measured data on the position of a particle moving man and back when walking, these data were then used for experimental realization of energy harvesting backpack and as input data to the simulation in Simulink, which brought us a comparison between theoretical assumptions and practical implementation. When measuring characteristics of energy harvesting system we have a problem with measurements on backpack solved when redoing of the hydraulic cylinder as a source of a suitable movement corresponding to the amplitude and frequency of human walk.

  15. Non-invasive assessment of arterial stiffness using oscillometric blood pressure measurement

    Directory of Open Access Journals (Sweden)

    Komine Hidehiko

    2012-02-01

    Full Text Available Abstract Background Arterial stiffness is a major contributor to cardiovascular diseases. Because current methods of measuring arterial stiffness are technically demanding, the purpose of this study was to develop a simple method of evaluating arterial stiffness using oscillometric blood pressure measurement. Methods Blood pressure was conventionally measured in the left upper arm of 173 individuals using an inflatable cuff. Using the time series of occlusive cuff pressure and the amplitudes of pulse oscillations, we calculated local slopes of the curve between the decreasing cuff pressure and corresponding arterial volume. Whole pressure-volume curve was derived from numerical integration of the local slopes. The curve was fitted using an equation and we identified a numerical coefficient of the equation as an index of arterial stiffness (Arterial Pressure-volume Index, API. We also measured brachial-ankle (baPWV PWV and carotid-femoral (cfPWV PWV using a vascular testing device and compared the values with API. Furthermore, we assessed carotid arterial compliance using ultrasound images to compare with API. Results The slope of the calculated pressure-volume curve was steeper for compliant (low baPWV or cfPWV than stiff (high baPWV or cfPWV arteries. API was related to baPWV (r = -0.53, P r = -0.49, P r = 0.32, P Conclusions These results suggest that our method can simply and simultaneously evaluate arterial stiffness and blood pressure based on oscillometric measurements of blood pressure.

  16. α-Solanine reverses pulmonary vascular remodeling and vascular angiogenesis in experimental pulmonary artery hypertension.

    Science.gov (United States)

    Nie, Xiaowei; Dai, Youai; Tan, Jianxin; Chen, Yuan; Qin, Guowei; Mao, Wenjun; Zou, Jian; Chang, Yanhua; Wang, Qian; Chen, Jingyu

    2017-12-01

    Similar to cancer, pulmonary arterial hypertension (PAH) is characterized by vascular remodeling, which leads to obliteration of the small pulmonary arteriole, with marked proliferation of pulmonary artery smooth muscle cells (PASMC) and/or endothelial cells dysfunction. Aberrant expression of tumor suppressor genes is closely associated with susceptibility to PAH. We hypothesized that α-solanine, a glycoalkaloid found in members of the nightshade family known to have antitumor activity in different cancers, reverses experimental PAH by activating the tumor suppressor-axis inhibition protein 2 (AXIN2). We investigated the effects of α-solanine on PASMC proliferation and apoptosis by using 5-ethynyl-2'-deoxyuridine proliferation assay, proliferating cell nuclear antigen and Ki67 staining, TUNEL and Anexine V assays. Scratch wound healing and tube formation assays were also used to study migration of endothelial cells. In vitro, we demonstrated, using cultured human PASMC from PAH patients, that α-solanine reversed dysfunctional AXIN2, β-catenin and bone morphogenetic protein receptor type-2 signaling, whereas restored [Ca]i, IL-6 and IL-8, contributing to the decrease of PAH-PASMC proliferation and resistance to apoptosis. Meanwhile, α-solanine inhibits proliferation, migration and tube formation of PAH-pulmonary artery endothelial cells by inhibiting Akt/GSK-3α activation. In vivo, α-solanine administration decreases distal pulmonary arteries remodeling, mean pulmonary arteries pressure and right ventricular hypertrophy in both monocrotaline-induced and Sugen/hypoxia-induced PAH in mice. This study demonstrates that AXIN2/β-catenin axis and Akt pathway can be therapeutically targeted by α-solanine in PAH. α-Solanine could be used as a new therapeutic strategy for the treatment of PAH.

  17. Comparison of non-invasive blood pressure monitoring using modified arterial applanation tonometry with intra-arterial measurement.

    Science.gov (United States)

    Harju, Jarkko; Vehkaoja, Antti; Kumpulainen, Pekka; Campadello, Stefano; Lindroos, Ville; Yli-Hankala, Arvi; Oksala, Niku

    2018-02-01

    Intermittent non-invasive blood pressure measurement with tourniquets is slow, can cause nerve and skin damage, and interferes with other measurements. Invasive measurement cannot be safely used in all conditions. Modified arterial tonometry may be an alternative for fast and continuous measurement. Our aim was to compare arterial tonometry sensor (BPro®) with invasive blood pressure measurement to clarify whether it could be utilized in the postoperative setting. 28 patients who underwent elective surgery requiring arterial cannulation were analyzed. Patients were monitored post-operatively for 2 h with standard invasive monitoring and with a study device comprising an arterial tonometry sensor (BPro®) added with a three-dimensional accelerometer to investigate the potential impact of movement. Recordings were collected electronically. The results revealed inaccurate readings in method comparison between the devices based on recommendations by Association for the Advancement of Medical Instrumentation (AAMI). On a Bland-Altman plot, the bias and precision between these two methods was 19.8 ± 16.7 (Limits of agreement - 20.1 to 59.6) mmHg, Spearman correlation coefficient r = 0.61. For diastolic pressure, the difference was 4.8 ± 7.7 (LoA - 14.1 to 23.6) mmHg (r = 0.72), and for mean arterial pressure it was 11.18 ± 11.1 (LoA - 12.1 to 34.2) mmHg (r = 0.642). Our study revealed inaccurate agreement (AAMI) between the two methods when measuring systolic and mean blood pressures during post-operative care. The readings for diastolic pressures were inside the limits recommended by AAMI. Movement increased the failure rate significantly (p invasive blood pressure measurement in these patients.

  18. The effect of thickness measurement on numerical arterial models.

    Science.gov (United States)

    de Gelidi, Serena; Tozzi, Gianluca; Bucchi, Andrea

    2017-07-01

    Several optical-based techniques for measuring the sample thickness (ST) of soft tissues have been proposed in the literature to overcome the limits of hand-operated procedures. However, ST measurement still remains arbitrary. The stress calculated during an experimental procedure, usually based on a constant thickness value for all samples, cannot be considered representative of the actual stress experienced by the tissue. Therefore, a new optical methodology to measure ST is proposed and compared to four different thickness estimations. A simplified aortic geometry, under physiologic pulsatile conditions, is used to assess the impact of ST measurement on stress predictions. An additional computational model investigates the effect of such thickness values on critical pressure levels that may instigate aneurysm formation in a homogeneous or artificially modified geometry. Comparing the results obtained for the application of a pulsatile load, wall stress values associated to minimum ST are at least 24kPa inferior to maximum ST. Critical pressure values appear to be inversely proportional to ST estimation: simulations, associated to maximum ST, predict aneurysm formation for pressure levels at least 7kPa inferior to minimum ST outcomes. Finally, the role of the strain-energy function used to fit the experimental data is demonstrated to be fundamental for predictions of aneurysm formation. Copyright © 2017. Published by Elsevier B.V.

  19. Classification of peripheral occlusive arterial diseases based on symptoms, signs and distal blood pressure measurements

    DEFF Research Database (Denmark)

    Tønnesen, K H; Noer, Ivan; Paaske, William

    1980-01-01

    Systolic blood pressures at toe and ankle were measured in 459 consecutive patients with occlusive arterial disease. Fifty-eight per cent had intermittent claudication with arterial disease of all degrees of severity. Seventeen per cent complained of rest pain having toe systolic pressures below 30...... occlusive arterial disease which was located distally on the legs. A classification in three groups is suggested: (1) ischemia only during exercise; (2) ischemia at rest with or without ulcerations: and (3) diabetics with chronic ulcerations....

  20. Measurement of Blood Pressure Using an Arterial Pulsimeter Equipped with a Hall Device

    Directory of Open Access Journals (Sweden)

    Jong-Gu Choi

    2011-01-01

    Full Text Available To measure precise blood pressure (BP and pulse rate without using a cuff, we have developed an arterial pulsimeter consisting of a small, portable apparatus incorporating a Hall device. Regression analysis of the pulse wave measured during testing of the arterial pulsimeter was conducted using two equations of the BP algorithm. The estimated values of BP obtained by the cuffless arterial pulsimeter over 5 s were compared with values obtained using electronic or liquid mercury BP meters. The standard deviation between the estimated values and the measured values for systolic and diastolic BP were 8.3 and 4.9, respectively, which are close to the range of values of the BP International Standard. Detailed analysis of the pulse wave measured by the cuffless radial artery pulsimeter by detecting changes in the magnetic field can be used to develop a new diagnostic algorithm for BP, which can be applied to new medical apparatus such as the radial artery pulsimeter.

  1. Treatment of secondary hyperparathyroidism by high calcium diet is associated with enhanced resistance artery relaxation in experimental renal failure.

    Science.gov (United States)

    Jolma, Pasi; Kööbi, Peeter; Kalliovalkama, Jarkko; Saha, Heikki; Fan, Meng; Jokihaara, Jarkko; Moilanen, Eeva; Tikkanen, Ilkka; Pörsti, Ilkka

    2003-12-01

    Vasorelaxation is impaired in renal failure (RF) and hypertension. A high calcium diet enhances vasodilatation and reduces blood pressure in experimental hypertension. Oral calcium salts are used as phosphate binders in RF. However, the effect of increased calcium intake on arterial tone in RF is unknown. We investigated the influence of an 8-week high calcium diet (0.3 vs 3.0%) on resistance artery tone in 5/6 nephrectomized (NTX) rats. Calcium was supplemented as carbonate salt, blood pressure measured by tail-cuff, urine collected in metabolic cages, and samples taken for blood chemistry and parathyroid hormone (PTH). Functional studies of isolated third-order branches of the mesenteric artery in vitro were performed using the Mulvany multimyograph. Plasma urea was elevated 1.6-fold and systolic blood pressure by 10 mmHg after NTX, while increased calcium intake was without effect on these variables. Plasma PTH and phosphate were raised following NTX, and suppressed by high calcium diet. Vasorelaxations induced by K(+) channel agonists 11,12-epoxyeicosatrienoic acid and levcromakalim were impaired after NTX. Vasorelaxation induced by acetylcholine was also reduced following NTX, and experiments with N(G)-nitro-L-arginine methyl ester, diclofenac and charybdotoxin + apamin suggested that the K(+) channel-mediated component of endothelium-dependent relaxation was deficient after NTX. Increased calcium intake corrected all impairments of vasodilatation in NTX rats. Deficient vasorelaxation via K(+) channels was normalized by high calcium diet in experimental RF. This effect was independent of the degree of renal impairment and blood pressure, but was associated with improved calcium metabolism: plasma levels of PTH and phosphate were decreased and ionized calcium was increased.

  2. Non-invasive assessment of arterial stiffness using oscillometric blood pressure measurement

    Science.gov (United States)

    2012-01-01

    Background Arterial stiffness is a major contributor to cardiovascular diseases. Because current methods of measuring arterial stiffness are technically demanding, the purpose of this study was to develop a simple method of evaluating arterial stiffness using oscillometric blood pressure measurement. Methods Blood pressure was conventionally measured in the left upper arm of 173 individuals using an inflatable cuff. Using the time series of occlusive cuff pressure and the amplitudes of pulse oscillations, we calculated local slopes of the curve between the decreasing cuff pressure and corresponding arterial volume. Whole pressure-volume curve was derived from numerical integration of the local slopes. The curve was fitted using an equation and we identified a numerical coefficient of the equation as an index of arterial stiffness (Arterial Pressure-volume Index, API). We also measured brachial-ankle (baPWV) PWV and carotid-femoral (cfPWV) PWV using a vascular testing device and compared the values with API. Furthermore, we assessed carotid arterial compliance using ultrasound images to compare with API. Results The slope of the calculated pressure-volume curve was steeper for compliant (low baPWV or cfPWV) than stiff (high baPWV or cfPWV) arteries. API was related to baPWV (r = -0.53, P blood pressure based on oscillometric measurements of blood pressure. PMID:22325084

  3. Non-invasive assessment of arterial stiffness using oscillometric blood pressure measurement.

    Science.gov (United States)

    Komine, Hidehiko; Asai, Yoshiyuki; Yokoi, Takashi; Yoshizawa, Mutsuko

    2012-02-10

    Arterial stiffness is a major contributor to cardiovascular diseases. Because current methods of measuring arterial stiffness are technically demanding, the purpose of this study was to develop a simple method of evaluating arterial stiffness using oscillometric blood pressure measurement. Blood pressure was conventionally measured in the left upper arm of 173 individuals using an inflatable cuff. Using the time series of occlusive cuff pressure and the amplitudes of pulse oscillations, we calculated local slopes of the curve between the decreasing cuff pressure and corresponding arterial volume. Whole pressure-volume curve was derived from numerical integration of the local slopes. The curve was fitted using an equation and we identified a numerical coefficient of the equation as an index of arterial stiffness (Arterial Pressure-volume Index, API). We also measured brachial-ankle (baPWV) PWV and carotid-femoral (cfPWV) PWV using a vascular testing device and compared the values with API. Furthermore, we assessed carotid arterial compliance using ultrasound images to compare with API. The slope of the calculated pressure-volume curve was steeper for compliant (low baPWV or cfPWV) than stiff (high baPWV or cfPWV) arteries. API was related to baPWV (r = -0.53, P blood pressure based on oscillometric measurements of blood pressure.

  4. Multiresolution Approach for Noncontact Measurements of Arterial Pulse Using Thermal Imaging

    Science.gov (United States)

    Chekmenev, Sergey Y.; Farag, Aly A.; Miller, William M.; Essock, Edward A.; Bhatnagar, Aruni

    This chapter presents a novel computer vision methodology for noncontact and nonintrusive measurements of arterial pulse. This is the only investigation that links the knowledge of human physiology and anatomy, advances in thermal infrared (IR) imaging and computer vision to produce noncontact and nonintrusive measurements of the arterial pulse in both time and frequency domains. The proposed approach has a physical and physiological basis and as such is of a fundamental nature. A thermal IR camera was used to capture the heat pattern from superficial arteries, and a blood vessel model was proposed to describe the pulsatile nature of the blood flow. A multiresolution wavelet-based signal analysis approach was applied to extract the arterial pulse waveform, which lends itself to various physiological measurements. We validated our results using a traditional contact vital signs monitor as a ground truth. Eight people of different age, race and gender have been tested in our study consistent with Health Insurance Portability and Accountability Act (HIPAA) regulations and internal review board approval. The resultant arterial pulse waveforms exactly matched the ground truth oximetry readings. The essence of our approach is the automatic detection of region of measurement (ROM) of the arterial pulse, from which the arterial pulse waveform is extracted. To the best of our knowledge, the correspondence between noncontact thermal IR imaging-based measurements of the arterial pulse in the time domain and traditional contact approaches has never been reported in the literature.

  5. Comparison of ambulatory blood pressure measurement with home, office and pharmacy measurements: is arterial blood pressure measured at pharmacy reliable?

    Science.gov (United States)

    Mutlu, Sinan; Sari, Oktay; Arslan, Erol; Aydogan, Umit; Doganer, Yusuf C; Koc, Bayram

    2016-02-01

    Standardizing arterial blood pressure (BP) measurement is difficult because of different performers like doctor or pharmacy employee. We investigated the reliability between different BP measurement methods. The study was conducted in an internal medicine service with 160 patients in Ankara, Turkey. First, the subjects' BP was measured by doctor. Then, 24-hour BP monitoring devices were placed. Participants were then instructed to measure their BPs both at home and in pharmacy. The next day, arterial BP was measured by the doctor for the second time. The prevalence rates of masked and white coat hypertension were 8.8% (n = 14) and 8.1% (n = 13), respectively. There was no statistically significant differences between ambulatory measurement and home, office and pharmacy measurements (P > 0.05). The consistency rate between ambulatory and home measurements was 97.5% (kappa = 0.947, P home measurement. There was a moderate positive correlation between ambulatory and other measurements in both systolic and diastolic values. There was a positive and very strong correlation between ambulatory and home measurements of systolic and diastolic ABP values (respectively; r = 0.926 and r = 0.968) and there was a statistically significant relation between these measurements (P home measurement when compared with ambulatory measurement. But both office and pharmacy measurements had also high sensitivity and specificity. © 2015 John Wiley & Sons, Ltd.

  6. Agreement between two oscillometric blood pressure technologies and invasively measured arterial pressure in the dog.

    Science.gov (United States)

    da Cunha, Anderson F; Ramos, Sara J; Domingues, Michelle; Beaufrère, Hugues; Shelby, Amanda; Stout, Rhett; Acierno, Mark J

    2016-03-01

    To compare two commonly used oscillometric technologies for obtaining noninvasive blood pressure (NIBP) measurements and to determine if there is a difference in agreement between these systems and invasive blood pressure (IBP) measurements. Prospective, experimental study. Twenty adult laboratory dogs. Each dog was anesthetized and its median caudal artery catheterized for IBP monitoring. An NIBP cuff was placed in the middle third of the antebrachium and attached to either monitor-1 or monitor-2. Four pairs of concurrent NIBP and IBP measurements were recorded with each monitor. Agreement between IBP and NIBP measurements was explored using Bland-Altman analysis, as well as the American College of Veterinary Internal Medicine (ACVIM) and Association for the Advancement of Medical Instrumentation (AAMI) guidelines for the validation of NIBP devices. Both NIBP technologies produced results that met the ACVIM and AAMI guidelines for the validation of NIBP devices. For monitor-1, analyses of agreement showed biases of 0.2 mmHg [95% limits of agreement (LoA) -11.8 to 12.3 mmHg] in systolic arterial pressure (SAP) values, -2.6 mmHg (95% LoA -14.4 to 9.1 mmHg) in diastolic arterial pressure (DAP) values, and -2.5 mmHg (95% LoA -12.7 to 7.3 mmHg) in mean arterial pressure (MAP) values. For monitor-2, analyses of agreement showed biases of 3.4 mmHg (95% LoA -8.7 to 15.5 mmHg) in SAP values, 2.2 mmHg (95% LoA -6.6 to 10.9 mmHg) in DAP values, and 1.6 mmHg (95% LoA -5.9 to 8.9 mmHg) in MAP values. Multi-function monitors can contain components from various manufacturers. Clinicians should consider whether these have been validated in the species to be monitored. Both of the technologies studied here seem appropriate for use in dogs. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

  7. Comparison of invasive blood pressure measurements from the caudal ventral artery and the femoral artery in male adult SD and Wistar rats.

    Directory of Open Access Journals (Sweden)

    Ying Wang

    Full Text Available BACKGROUND AND PURPOSE: Studies have suggested that the caudal ventral artery is a potential site for continuous arterial blood pressure monitoring in rats. However, the agreement of mean arterial pressure values between the femoral artery and the caudal ventral artery has not been investigated. This study was performed to identify whether the caudal ventral artery could be safely used for continuous blood pressure monitoring as an alternative site to the femoral artery. METHODS: Rats were randomized into four groups: Sprague Dawley rats under normothermia; Wistar rats under normothermia; Sprague Dawley rats under hypothermia; Wistar rats under hypothermia. Each rat underwent simultaneous monitoring of blood pressure using femoral artery and caudal ventral artery catheterization during a stable hemodynamic state and three periods of acute severe hemodynamic changes. The effects of rat strain, rectal temperature, experimental time course and hemodynamic factors on pressure gradients, the concordance of mean arterial pressure values between the femoral artery and the caudal ventral artery, and the rates of distal ischemia after surgery were determined. RESULTS: There was a significant difference in the rate of distal ischemia between femoral and caudal ventral arteries after catheterization (25% vs 5%, P<0.05. The overall mean gradient and the mean gradient under a steady hemodynamic state were 4.9±3.7 mm Hg and 5.5±2.5 mm Hg, respectively. The limits of agreement (bias±1.96 SD were (-2.5 mm Hg, 12.3 mm Hg and (-0.5 mm Hg, 10.5 mm Hg, respectively. Although the concordance decreased during the first 30 sec of each period of severe hemodynamic changes, the degree of agreement was acceptable regardless of the effects of rat strain and rectal temperature. CONCLUSIONS: Based on the degree of agreement and the safety of catheterization, the caudal ventral artery may be a preferred site for continuous arterial blood pressure monitoring without acute

  8. Arterial Spin Labeling (ASL fMRI: Advantages, Theoretical Constrains and Experimental Challenges in Neurosciences

    Directory of Open Access Journals (Sweden)

    Ajna Borogovac

    2012-01-01

    Full Text Available Cerebral blood flow (CBF is a well-established correlate of brain function and therefore an essential parameter for studying the brain at both normal and diseased states. Arterial spin labeling (ASL is a noninvasive fMRI technique that uses arterial water as an endogenous tracer to measure CBF. ASL provides reliable absolute quantification of CBF with higher spatial and temporal resolution than other techniques. And yet, the routine application of ASL has been somewhat limited. In this review, we start by highlighting theoretical complexities and technical challenges of ASL fMRI for basic and clinical research. While underscoring the main advantages of ASL versus other techniques such as BOLD, we also expound on inherent challenges and confounds in ASL perfusion imaging. In closing, we expound on several exciting developments in the field that we believe will make ASL reach its full potential in neuroscience research.

  9. Experimental Measurement of In Situ Stress

    Science.gov (United States)

    Tibbo, Maria; Milkereit, Bernd; Nasseri, Farzine; Schmitt, Douglas; Young, Paul

    2016-04-01

    The World Stress Map data is determined by stress indicators including earthquake focal mechanisms, in situ measurement in mining, oil and gas boreholes as well as the borehole cores, and geologic data. Unfortunately, these measurements are not only infrequent but sometimes infeasible, and do not provide nearly enough data points with high accuracy to correctly infer stress fields in deep mines around the world. Improvements in stress measurements of Earth's crust is fundamental to several industries such as oil and gas, mining, nuclear waste management, and enhanced geothermal systems. Quantifying the state of stress and the geophysical properties of different rock types is a major complication in geophysical monitoring of deep mines. Most stress measurement techniques involve either the boreholes or their cores, however these measurements usually only give stress along one axis, not the complete stress tensor. The goal of this project is to investigate a new method of acquiring a complete stress tensor of the in situ stress in the Earth's crust. This project is part of a comprehensive, exploration geophysical study in a deep, highly stressed mine located in Sudbury, Ontario, Canada, and focuses on two boreholes located in this mine. These boreholes are approximately 400 m long with NQ diameters and are located at depths of about 1300 - 1600 m and 1700 - 2000 m. Two borehole logging surveys were performed on both boreholes, October 2013 and July 2015, in order to perform a time-lapse analysis of the geophysical changes in the mine. These multi-parameter surveys include caliper, full waveform sonic, televiewer, chargeability (IP), and resistivity. Laboratory experiments have been performed on borehole core samples of varying geologies from each borehole. These experiments have measured the geophysical properties including elastic modulus, bulk modulus, P- and S-wave velocities, and density. The apparatus' used for this project are geophysical imaging cells capable

  10. The Effect of Ozone Therapy on Experimental Vasospasm in the Rat Femoral Artery.

    Science.gov (United States)

    Orakdogen, Metin; Uslu, Serap; Emon, Selin Tural; Somay, Hakan; Meric, Zeynep Cingu; Hakan, Tayfun

    2016-01-01

    Oxidation products following subarachnoid hemorrhage (SAH) are among the causative substances of cerebral vasospasm and poor outcome. Ozone (O3) is a gas that contains three atoms of oxygen with a cyclic structure. It has been suggested that application of low-dose ozone has an antioxidant effect and provides resistance to oxidative stress. We investigated the effect of oxygen-ozone therapy on rat femoral artery vasospasm. Twenty-four male Sprague-Dawley rats were randomly separated into vasospasm, vasospasm + ozone and control groups. The femoral artery vasospasm model was used. Rats in the vasospasm + ozone group were given 4 mL of ozone (20 μ/mL) daily for 7 days. Femoral arteries were examined by light microscopy for histological changes and morphometric analysis. Kruskal Wallis test and Mann Whitney U tests were used for the statistical analysis. The values of p Ozone treatment reduced the morphometric changes as irregularity of the elastic lamina, disruption of the endothelial cells, vacuolization and hemorrhages that caused by vasospasm. The measurements of the wall thickness (p=0.003; p ozone groups. Ozone therapy may be useful in the treatment of post-hemorrhagic vasospasm.

  11. High glucose concentration does not modulate the formation of arterial medial calcification in experimental uremic rats.

    Science.gov (United States)

    Yoshida, Tadashi; Yamashita, Maho; Horimai, Chihiro; Hayashi, Matsuhiko

    2013-01-01

    High phosphate-induced phenotypic switching of smooth muscle cells (SMCs) into osteogenic cells is critical for the formation of arterial medial calcification in chronic kidney disease. Because vascular calcification is also prevalent in type 2 diabetes, we examined whether glucose concentration affects high phosphate-induced SMC phenotypic switching and calcification. First, the formation of arterial medial calcification was compared among 4 groups: adenine-fed uremic rats, streptozotocin-injected hyperglycemic rats, adenine-fed and streptozotocin-injected uremic/hyperglycemic rats, and control rats. Calcification was obvious in uremic and uremic/hyperglycemic rats, whereas it was undetectable in the others. Aortic calcium contents were significantly elevated in uremic and uremic/hyperglycemic rats, but they were not different between the two groups. Moreover, hyperglycemia had no effects on the reduced expression of SMC differentiation markers including smooth muscle α-actin and SM22α and on the increased expression of osteogenic markers, such as Runx2, in uremic rats. Second, cultured SMCs were incubated in the medium with various concentrations of phosphate (0.9-4.5 mmol/l) and glucose (5-50 mmol/l), and calcium deposition was measured. Although high phosphate dose-dependently increased calcium contents, they were unaffected by glucose concentration. Results suggest that glucose concentration does not directly modulate high phosphate-induced SMC phenotypic switching and arterial medial calcification. © 2013 S. Karger AG, Basel.

  12. The baboon (Papio anubis extracranial carotid artery: An anatomical guide for endovascular experimentation

    Directory of Open Access Journals (Sweden)

    Laufer Ilya

    2001-12-01

    Full Text Available Abstract Background As novel endovascular strategies are developed for treating neurological disease, there is an increasing need to evaluate these techniques in relevant preclinical models. The use of non-human primates is especially critical given their structural and physiological homology with humans. In order to conduct primate endovascular studies, a comprehensive understanding of the carotid anatomy is necessary. We therefore performed a detailed examination of the vessel lengths, lumen diameters and angles of origin of the baboon extracranial carotid system. Methods We characterized the extracranial carotid system often male baboons (Papio anubis, range 15.1–28.4 kg by early post-mortem dissection. Photographic documentation of vessel lengths, lumen diameters, and angles of origin were measured for each segment of the carotid bilaterally. Results The common carotid arteries averaged 94.7 ± 1.7 mm (left and 87.1 ± 1.6 mm (right in length. The average minimal common carotid lumen diameters were 3.0 ± 0.3 mm (left and 2.9 ± 0.2 mm (right. Each animal had a common brachiocephalic artery arising from the aorta which bifurcated into the left common carotid artery and right braciocephalic artery after 21.5 ± 1.6 mm. The vascular anatomy was found to be consistent among animals despite a wide range of animal weights. Conclusions The consistency in the Papio anubis extracranial carotid system may promote the use of this species in the preclinical investigation of neuro-interventional therapies.

  13. Comparison of Doppler, oscillometric, auricular and carotid arterial blood pressure measurements in isoflurane anesthetized New Zealand white rabbits.

    Science.gov (United States)

    Barter, Linda S; Epstein, Steven E

    2014-07-01

    To assess agreement between carotid arterial pressure and auricular arterial, thoracic limb Doppler or thoracic limb oscillometric blood pressure measurements. Prospective experimental study. Six adult New Zealand white rabbits. Rabbits were anesthetized with isoflurane in oxygen at 1, 1.5 and 2 MAC on two separate occasions. Catheters in the auricular and the contralateral external carotid artery were connected to calibrated pressure transducers via non-compliant tubing. Inflatable cuffs of width equal to approximately 40% of the limb circumference were placed above the carpus on both thoracic limbs with a Doppler transducer placed distal to the cuff on one. Systolic (SAP) and mean (MAP) arterial blood pressure measurements were obtained at each dose, on each occasion. Agreement between measurement techniques was evaluated by repeated measures Bland Altman analysis with carotid pressure as the reference. Variation in bias over the measurement range was evaluated by regression analysis. Carotid MAP and SAP ranged from 20 to 65 mmHg and 37 to 103 mmHg respectively. Bias and 95% limits of agreement for auricular and oscillometric MAP were 7 (0-14) and -5 (-21-11) mmHg, respectively, and for auricular, oscillometric and Doppler SAP were 23 (8-37), -2 (-24-20) and 13 (-14-39) mmHg, respectively. Bias varied significantly over the measurement range (p < 0.001) for all three SAP techniques but not for MAP measurements. Limits of agreement for all measurements were large but less so for MAP than SAP. Variation in bias with SAP should be considered when using these measurements clinically. © 2014 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

  14. Semi-automatic quantitative measurements of intracranial internal carotid artery stenosis and calcification using CT angiography

    NARCIS (Netherlands)

    Bleeker, Leslie; Marquering, Henk A.; van den Berg, René; Nederkoorn, Paul J.; Majoie, Charles B.

    2012-01-01

    Intracranial carotid artery atherosclerotic disease is an independent predictor for recurrent stroke. However, its quantitative assessment is not routinely performed in clinical practice. In this diagnostic study, we present and evaluate a novel semi-automatic application to quantitatively measure

  15. The Involvement of a Polyphenol-Rich Extract of Black Chokeberry in Oxidative Stress on Experimental Arterial Hypertension

    Directory of Open Access Journals (Sweden)

    Manuela Ciocoiu

    2013-01-01

    Full Text Available The aim of this study is to characterize the content of Aronia melanocarpa Elliott (black chokeberry extract and also to estimate the influence of polyphenolic compounds contained in chokeberries on oxidative stress, on an L-NAME-induced experimental model of arterial hypertension. The rat blood pressure values were recorded using a CODA Noninvasive Blood Pressure System. HPLC/DAD coupled with ElectroSpray Ionization-Mass Spectrometry allowed identification of five phenolic compounds in berries ethanolic extract as follows: chlorogenic acid, kuromanin, rutin, hyperoside, and quercetin. The serous activity of glutathione-peroxidase (GSH-Px has significantly lower values in the hypertensive (AHT group as compared to the group protected by polyphenols (AHT + P. The total antioxidant capacity (TAC values are lower in the AHT group and they are significantly higher in the AHT + P group. All the measured blood pressure components revealed a biostatistically significant blood pressure drop between the AHT group and the AHT + P group. The results reveal the normalization of the reduced glutathion (GSH concentration as well as a considerable reduction in the malondialdehyde (MDA serum concentration in the AHT + P group. Ethanolic extract of black chokeberry fruits not only has a potential value as a prophylactic agent but also may function as a nutritional supplement in the management of arterial hypertension.

  16. Arterial input function in a dedicated slice for cerebral perfusion measurements in humans.

    Science.gov (United States)

    Kellner, Elias; Mader, Irina; Reisert, Marco; Urbach, Horst; Kiselev, Valerij Gennadevic

    2017-12-09

    We aimed to modify our previously published method for arterial input function measurements for evaluation of cerebral perfusion (dynamic susceptibility contrast MRI) such that it can be applied in humans in a clinical setting. Similarly to our previous work, a conventional measurement sequence for dynamic susceptibility contrast MRI is extended with an additional measurement slice at the neck. Measurement parameters at this slice were optimized for the blood signal (short echo time, background suppression, magnitude and phase images). Phase-based evaluation of the signal in the carotid arteries is used to obtain quantitative arterial input functions. In all pilot measurements, quantitative arterial input functions were obtained. The resulting absolute perfusion parameters agree well with literature values (gray and white matter mean values of 46 and 24 mL/100 g/min, respectively, for cerebral blood flow and 3.0% and 1.6%, respectively, for cerebral blood volume). The proposed method has the potential to quantify arterial input functions in the carotid arteries from a direct measurement without any additional normalization.

  17. Acoustic hemostasis of porcine superficial femoral artery: Simulation and in-vivo experimental studies

    Science.gov (United States)

    Zeng, Xiaozheng; Mitchell, Stuart; Miller, Matthew; Barnes, Stephen; Hopple, Jerry; Kook, John; Moreau-Gobard, Romain; Hsu, Stephen; Ahiekpor-Dravi, Alexis; Crum, Lawrence A.; Eaton, John; Wong, Keith; Sekins, K. Michael

    2012-10-01

    In-vivo focused ultrasound studies were computationally simulated and conducted experimentally with the aim of occluding porcine superficial femoral arteries (SFA) via thermal coagulation. A multi-array HIFU applicator was used which electronically scanned multiple beam foci around the target point. The spatio-temporally averaged acoustic and temperature fields were simulated in a fluid dynamics and acousto-thermal finite element model with representative tissue fields, including muscle, vessel and blood. Simulations showed that with an acoustic power of 200W and a dose time of 60s, perivascular tissue reached 91°C; and yet blood reached a maximum 59°C, below the coagulation objective for this dose regime (75°C). Per simulations, acoustic-streaming induced velocity in blood reached 6.1cm/s. In in-vivo experiments, several arteries were treated. As simulated, thermal lesions were observed in muscle surrounding SFA in all cases. In dosing limited to 30 to 60 seconds, it required 257W to provide occlusion (one complete and one partial occlusion). Angiography and histology showed evidence of thrombogenesis and collagen shrinkage-based vessel constriction at these doses.

  18. Brachial artery vasomotion and transducer pressure effect on measurements by active contour segmentation on ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    Cary, Theodore W.; Sultan, Laith R.; Sehgal, Chandra M., E-mail: sehgalc@uphs.upenn.edu [Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Reamer, Courtney B.; Mohler, Emile R. [Department of Medicine, Division of Cardiovascular Medicine, Section of Vascular Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2014-02-15

    Purpose: To use feed-forward active contours (snakes) to track and measure brachial artery vasomotion on ultrasound images recorded in both transverse and longitudinal views; and to compare the algorithm's performance in each view. Methods: Longitudinal and transverse view ultrasound image sequences of 45 brachial arteries were segmented by feed-forward active contour (FFAC). The segmented regions were used to measure vasomotion artery diameter, cross-sectional area, and distention both as peak-to-peak diameter and as area. ECG waveforms were also simultaneously extracted frame-by-frame by thresholding a running finite-difference image between consecutive images. The arterial and ECG waveforms were compared as they traced each phase of the cardiac cycle. Results: FFAC successfully segmented arteries in longitudinal and transverse views in all 45 cases. The automated analysis took significantly less time than manual tracing, but produced superior, well-behaved arterial waveforms. Automated arterial measurements also had lower interobserver variability as measured by correlation, difference in mean values, and coefficient of variation. Although FFAC successfully segmented both the longitudinal and transverse images, transverse measurements were less variable. The cross-sectional area computed from the longitudinal images was 27% lower than the area measured from transverse images, possibly due to the compression of the artery along the image depth by transducer pressure. Conclusions: FFAC is a robust and sensitive vasomotion segmentation algorithm in both transverse and longitudinal views. Transverse imaging may offer advantages over longitudinal imaging: transverse measurements are more consistent, possibly because the method is less sensitive to variations in transducer pressure during imaging.

  19. Measure of tissue resistivity in experimental electrical burns.

    Science.gov (United States)

    Chilbert, M; Maiman, D; Sances, A; Myklebust, J; Prieto, T E; Swiontek, T; Heckman, M; Pintar, K

    1985-03-01

    Studies were conducted in 14 mongrel dogs to compare resistivities in normal muscle with those from muscle subjected to electrical burns. One-ampere, 60-Hz currents were passed between the hind limbs of the dogs producing injury in three measurement regions of the gracilis muscle. Histology, heart rate, body temperature, arterial and pulmonary artery pressure, cardiac output, hematocrit, leukocyte counts, fibrinogen levels, and platelet levels were determined. Muscle resistivity associated with severe tissue necrosis was 70% lower than control values. Resistivity in tissue showing edema and minimal necrosis decreased 20 to 40% from control values. Muscle showing only edema had a 10 to 30% decrease in resistivity.

  20. Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180° Curved Artery Test Section.

    Science.gov (United States)

    Bulusu, Kartik V; Plesniak, Michael W

    2016-07-19

    The arterial network in the human vasculature comprises of ubiquitously present blood vessels with complex geometries (branches, curvatures and tortuosity). Secondary flow structures are vortical flow patterns that occur in curved arteries due to the combined action of centrifugal forces, adverse pressure gradients and inflow characteristics. Such flow morphologies are greatly affected by pulsatility and multiple harmonics of physiological inflow conditions and vary greatly in size-strength-shape characteristics compared to non-physiological (steady and oscillatory) flows (1 - 7). Secondary flow structures may ultimately influence the wall shear stress and exposure time of blood-borne particles toward progression of atherosclerosis, restenosis, sensitization of platelets and thrombosis (4 - 6, 8 - 13). Therefore, the ability to detect and characterize these structures under laboratory-controlled conditions is precursor to further clinical investigations. A common surgical treatment to atherosclerosis is stent implantation, to open up stenosed arteries for unobstructed blood flow. But the concomitant flow perturbations due to stent installations result in multi-scale secondary flow morphologies (4 - 6). Progressively higher order complexities such as asymmetry and loss in coherence can be induced by ensuing stent failures vis-à-vis those under unperturbed flows (5). These stent failures have been classified as "Types I-to-IV" based on failure considerations and clinical severity (14). This study presents a protocol for the experimental investigation of the complex secondary flow structures due to complete transverse stent fracture and linear displacement of fractured parts ("Type IV") in a curved artery model. The experimental method involves the implementation of particle image velocimetry (2C-2D PIV) techniques with an archetypal carotid artery inflow waveform, a refractive index matched blood-analog working fluid for phase-averaged measurements (15 - 18

  1. Anterior temporal artery tap to identify systemic interference using short-separation NIRS measurements

    DEFF Research Database (Denmark)

    Sood, Mehak; Jindal, Utkarsh; Chowdhury, Shubhajit Roy

    2015-01-01

    that are also affected by tDCS. An approach may be to use short optode separations to measure systemic hemodynamic fluctuations occurring in the superficial layers which can then be used as regressors to remove the systemic contamination. Here, we demonstrate that temporal artery tap may be used to better...... change in the mean rSO2 better correlated with the corresponding percent change in log-transformed mean-power of EEG within 0.5 Hz-11.25 Hz frequency band after removing the systemic contamination using the temporal artery tap method. Based on our findings, we propose that anterior temporal artery tap...

  2. Novel formula to measure mean pulmonary artery pressure

    Directory of Open Access Journals (Sweden)

    Francisco Jose Chacon-Lozsan

    2016-11-01

    Full Text Available Mean Pulmonary Arterial Pressure (MPAP is an important parameter in evaluation of patients with pulmonary hypertension. The aim of this study is to correlate a new formula using non-invasive blood pressure and Bernoulli’s right ventricle systolic pressure (RVSP with invasive method. To archive the objectives, we enrolled 143 patients with suspected pulmonary hypertension from January 2015 till January 2016; all patients underwent right heart catheter evaluation and simultaneously RVSP by transthoracic echocardiography and non-invasive blood pressure to calculate MPAP by the formula MPAP = Pulse Pressure / (Mean Arterial Pressure/RVSP; and the results were compared using the Pearson’s simple-linear correlation method. We found a significant association between invasive and equation results with a Pearson’s correlation of 0,872 with a confidence interval from 0,795 to 0,921; sensitivity was 1,538% with a 95% confidence of interval (CI from 0,038% to 8,276%, and Specificity was 100% with 95% CI from 94,48% to 100%. Our results suggest that the new formula have a good correlation estimating MPAP compared with invasive right heart catheterization method.

  3. How Korotkoff, the surgeon, discovered the auscultatory method of measuring arterial pressure.

    Science.gov (United States)

    Segall, H N

    1975-10-01

    The Korotkoff sounds that measure systolic and diastolic arterial pressure levels were described in a brief communication by N.C. Korotkoff in 1905. He did not state how it happened that he discovered this auscultatory method of measuring "blood" pressure. The search for information on this matter led to studying the thesis for his doctorate published in 1910 on Experiments for Determining the Efficiency of Arterial Collaterals. It seems that when he wanted to be sure that pressureonan artery (digital, or with an Esmarch ligature or a Riva-Rocci cuff) had completely obliterated its lumen, he listened over the artery below the area of pressure. The absence of any sounds meant complete obliteration; a sound appeared with each beat when some flow did occur during partial obliteration of the lumen and when no pulsation could be detected because of the small volume of flow.

  4. Cardioprotective effects of early and late aerobic exercise training in experimental pulmonary arterial hypertension.

    Science.gov (United States)

    Moreira-Gonçalves, Daniel; Ferreira, Rita; Fonseca, Hélder; Padrão, Ana Isabel; Moreno, Nuno; Silva, Ana Filipa; Vasques-Nóvoa, Francisco; Gonçalves, Nádia; Vieira, Sara; Santos, Mário; Amado, Francisco; Duarte, José Alberto; Leite-Moreira, Adelino F; Henriques-Coelho, Tiago

    2015-11-01

    Clinical studies suggest that aerobic exercise can exert beneficial effects in pulmonary arterial hypertension (PAH), but the underlying mechanisms are largely unknown. We compared the impact of early or late aerobic exercise training on right ventricular function, remodeling and survival in experimental PAH. Male Wistar rats were submitted to normal cage activity (SED), exercise training in early (EarlyEX) and in late stage (LateEX) of PAH induced by monocrotaline (MCT, 60 mg/kg). Both exercise interventions resulted in improved cardiac function despite persistent right pressure-overload, increased exercise tolerance and survival, with greater benefits in EarlyEX+MCT. This was accompanied by improvements in the markers of cardiac remodeling (SERCA2a), neurohumoral activation (lower endothelin-1, brain natriuretic peptide and preserved vascular endothelial growth factor mRNA), metabolism and mitochondrial oxidative stress in both exercise interventions. EarlyEX+MCT provided additional improvements in fibrosis, tumor necrosis factor-alpha/interleukin-10 and brain natriuretic peptide mRNA, and beta/alpha myosin heavy chain protein expression. The present study demonstrates important cardioprotective effects of aerobic exercise in experimental PAH, with greater benefits obtained when exercise training is initiated at an early stage of the disease.

  5. Single sweep three-dimensional carotid ultrasound: reproducibility in plaque and artery volume measurements.

    Science.gov (United States)

    Kalashyan, Hayrapet; Shuaib, Ashfaq; Gibson, Patrick H; Romanchuk, Helen; Saqqur, Maher; Khan, Khurshid; Osborne, Jonathon; Becher, Harald

    2014-02-01

    There is a need for non-invasive and accurate techniques for assessment of severity of atherosclerotic disease in the carotid arteries. Recently an automated single sweep three-dimensional ultrasound (3D US) technique became available. The aims of this study were to evaluate the feasibility and reproducibility of the automated single sweep method in a cohort of patients undergoing clinically indicated carotid ultrasound. Consecutive patients with a history of stroke or transient ischemic attack (TIA) and having a plaque in the internal carotid artery (ICA) were recruited for this study. Imaging was performed using a Philips iU 22 ultrasound system equipped with the single sweep volumetric transducer vL 13-5. Analysis was performed offline with software provided by the manufacturer. Two independent observers performed all measurements. Of 137 arteries studied (from 79 patients), plaque and artery volumes could be measured in 106 (77%). Reproducibility of plaque volume measurements was assessed in 82 arteries. Bland-Altman analysis demonstrated good inter-observer reproducibility with limits of agreement -0.06 to +0.07 ml. The mean percentage difference between two observers was 5.6% ± 6.0%. Reproducibility of artery volume measurement was assessed in 31 cases. Bland-Altman analysis demonstrated limits of agreement from -0.15 to +0.15 ml. The mean percentage difference was 6.4 ± 5.9%. The new automated single sweep 3D ultrasound is feasible in the majority of patients. Good reproducibility in plaque and artery volume measurements makes this technique suitable for serial assessment of carotid plaques. Copyright © 2014 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  6. Use of a wireless system to measure invasive arterial blood pressure in ponies - preliminary study.

    Science.gov (United States)

    Ricco, Carolina H; Quandt, Jane E; Novo, Roberto E; Killos, Maria; Graham, Lynelle

    2009-01-01

    To evaluate the feasibility and functionality of intra-carotid wireless device implantation in ponies, and to investigate its short-term complications. Prospective preliminary study. Five mixed breed, adult, intact male ponies weighing 104 +/- 28.8 kg (mean +/- SD) underwent surgery. Arterial blood pressure data were continuously collected from four animals. General anesthesia was induced on two consecutive days. On the first day, an intra-arterial wireless device was implanted in the right carotid artery. On the next day, a transcutaneous intra-arterial catheter was placed in the left facial artery. Data from both sources were collected. Post-mortem examination was performed. Surgical time was 27.1 +/- 11.85 minutes. All catheters remained in place with some extra vascular migration. Complications included mild seroma and hematoma. The wireless system allowed continuous monitoring in ponies throughout anesthesia and at rest and may allow for the recording of arterial blood pressure and heart rate when it would be difficult to achieve with a conventional system (e.g. during recovery from anesthesia). The wireless invasive blood pressure monitor may allow continuous measurements when only intermittent measurements would be feasible with a wired system.

  7. Simultaneous comparison of thoracic bioimpedance and arterial pulse waveform-derived cardiac output with thermodilution measurement.

    Science.gov (United States)

    Hirschl, M M; Kittler, H; Woisetschläger, C; Siostrzonek, P; Staudinger, T; Kofler, J; Oschatz, E; Bur, A; Gwechenberger, M; Laggner, A N

    2000-06-01

    To compare the accuracy and reliability of thoracic electrical bioimpedance (TEB) and the arterial pulse waveform analysis with simultaneous measurement of thermodilution cardiac output (TD-CO) in critically ill patients. Prospective data collection. Emergency department and critical care unit in a 2,000-bed inner-city hospital. A total of 29 critically ill patients requiring invasive hemodynamic monitoring for clinical management were prospectively studied. Noninvasive cardiac output was simultaneously measured by a TEB device and by analysis of the arterial pulse waveform derived from the finger artery. Invasive cardiac output was determined by the thermodilution technique. A total of 175 corresponding TD-CO and noninvasive hemodynamic measurements were collected in 30-min intervals. They revealed an overall bias of 0.34 L/min/m2 (95% confidence interval, 0.24-0.44 L/min/m2; p 0.50 L/min/m2. The discrepancies of the arterial pulse waveform analysis correlated positively with the magnitude of the cardiac index (r2 = 0.29; p 0.50 L/min/m2. The magnitude of the discrepancies of the TEB was significantly correlated with age (r2 = 0.17; p = .02). Measurements were in phase in 93.2% of all arterial pulse waveform analysis and in 84.9% of all TEB readings (p < .001). The arterial pulse waveform analysis exhibits a greater accuracy and reliability as compared with the TEB with regard to overall bias, number of inaccurate readings, and phase lags. The arterial pulse waveform analysis may be useful for the monitoring of hemodynamic changes. However, both methods fail to be a substitute for the TD-CO because of a substantial percentage of inaccurate readings.

  8. Experimental Fracture Measurements of Functionally Graded Materials

    Science.gov (United States)

    Carpenter, Ray Douglas

    The primary objective of this research was to extend established fracture toughness testing methods to a new class of engineering materials known as functionally graded materials (FGMs). Secondary goals were to compare experimental results to those predicted by finite element models and to provide fracture test results as feedback toward optimizing processing parameters for the in-house synthesis of a MoSi2/SiC FGM. Preliminary experiments were performed on commercially pure (CP) Ti and uniform axial tensile tests resulted in mechanical property data including yield strength, 268 MPa, ultimate tensile strength, 470 MPa and Young's modulus, 110 GPa. Results from 3-point bending fracture experiments on CP Ti demonstrated rising R-curve behavior and experimentally determined JQ fracture toughness values ranged between 153 N/mm and 254 N/mm. Similar experimental protocols were used for fracture experiments on a 7- layered Ti/TiB FGM material obtained from Cercom in Vista, California. A novel technique for pre-cracking in reverse 4-point bending was developed for this ductile/brittle FGM material. Fracture test results exhibited rising R-curve behavior and estimated JQ fracture toughness values ranged from 0.49 N/mm to 2.63 N/mm. A 5- layered MoSi2/SiC FGM was synthesized using spark plasma sintering (SPS). Samples of this material were fracture tested and the results again exhibited a rising R-curve with KIC fracture toughness values ranging from 2.7 MPa-m1/2 to 6.0 MPa-m1/2. Finite Element Models predicted rising R-curve behavior for both of the FGM materials tested. Model results were in close agreement for the brittle MoSi2/SiC FGM. For the relatively more ductile Ti/TiB material, results were in close agreement at short crack lengths but diverged at longer crack lengths because the models accounted for fracture toughening mechanisms at the crack tip but not those acting in the crack wake.

  9. Comparison of noninvasive oscillometric and intra-arterial blood pressure measurements in hyperacute stroke.

    Science.gov (United States)

    Manios, Efstathios; Vemmos, Konstantinos; Tsivgoulis, Georgios; Barlas, Gerasimos; Koroboki, Eleni; Eleni, Koroboki; Spengos, Konstantinos; Zakopoulos, Nikolaos

    2007-06-01

    This study aims to compare automatic oscillometric blood pressure recordings with simultaneous direct intra-arterial blood pressure measurements in hyperacute stroke patients to test the accuracy of oscillometric readings. A total of 51 first-ever stroke patients underwent simultaneous noninvasive automatic oscillometric and intra-arterial blood pressure monitoring within 3 h of ictus. Casual blood pressure was measured in both arms using a standard mercury sphygmomanometer on hospital admission. Patients who received antihypertensive medication during the blood pressure monitoring were excluded. The estimation of systolic blood pressure (SBP) using oscillometric recordings underestimated direct radial artery SBP by 9.7 mmHg (95% confidence interval: 6.5-13.0, Pblood pressure (DBP) recordings were compared with intra-arterial DBP recordings. For SBP and DBP, the Pearson correlation coefficients between noninvasive and intra-arterial recordings were 0.854 and 0.832, respectively. When the study population was stratified according to SBP bands (group A: SBP160 mmHg and SBP180 mmHg), higher mean DeltaSBP (intra-arterial SBP-oscillometric SBP) levels were documented in group C (+19.8 mmHg, 95% confidence intervals: 12.2-27.4) when compared with groups B (+8.5 mmHg, 95% confidence intervals: 2.7-14.5; P=0.025) and A (+5.9 mmHg, 95% confidence intervals: 1.8-9.9; P=0.002). Noninvasive automatic oscillometric BP measurements underestimate direct SBP recordings and overestimate direct DBP readings in acute stroke. The magnitude of the discrepancy between intra-arterial and oscillometric SBP recordings is even more prominent in patients with critically elevated SBP levels.

  10. Relating external compressing pressure to mean arterial pressure in non-invasive blood pressure measurements.

    Science.gov (United States)

    Chin, K Y; Panerai, R B

    2015-01-01

    Arterial volume clamping uses external compression of an artery to provide continuous non-invasive measurement of arterial blood pressure. It has been assumed that mean arterial pressure (MAP) corresponds to the point where unloading leads to the maximum oscillation of the arterial wall as reflected by photoplethysmogram (PPG), an assumption that has been challenged. Five subjects were recruited for the study (three males, mean age (SD) = 32 (15) years). The PPG waveform was analysed to identify the relationship between the external compressing pressure, PPG pulse amplitude and MAP. Two separate tests were carried out at compression step intervals of 10 mmHg and 2 mmHg, respectively. No significant differences were found between the two tests. The bias between the compressing pressure and the MAP was -4.7 ± 5.63 mmHg (p < 0.001) showing a normal distribution. Further research is needed to identify optimal algorithms for estimation of MAP using PPG associated with arterial compression.

  11. A New Method to Measure Portal Venous and Hepatic Arterial Blood Flow Patients Intraoperatively

    Science.gov (United States)

    Jakab, F.; Ráth, Z.; Schmal, F.; Nagy, P.; Faller, J.

    1996-01-01

    The intraoperative measurement of the afferent circulation of the liver, namely the hepatic artery flow and portal venous flow was carried out upon 14 anesthetized patients having carcinoma in the splanchnic area, mainly in the head of the pancreas by means of transit time ultrasonic volume flowmeter. The hepatic artery flow, portal venous flow and total hepatic flow were 0.377±0.10; 0.614±0.21; 0.992±0.276 l/min respectively. The ratio of hepatic arterical flow to portal venous flow was 0.66±0.259 There was a sharp, significant increase in hepatic arterial flow (29.8±6.1%, p<0,01) after the temporary occlusion of the portal vein, while the temporary occlusion of hepatic artery did not have any significant effect on portal venous circulation. The interaction between hepatic arterial flow and portal venous flow is a much disputed question, but according to the presented data here, it is unquestionable, that the decrease of portal venous flow immediately results a significant increase in hepatic artery circulation. PMID:8809586

  12. MR velocity mapping measurement of renal artery blood flow in patients with impaired kidney function

    DEFF Research Database (Denmark)

    Cortsen, M; Petersen, L.J.; Stahlberg, F

    1996-01-01

    . MR velocity mapping was performed in both renal arteries using an ECG-triggered gradient echo pulse sequence previously validated in normal volunteers. Effective renal plasma flow was calculated from the clearance rate of PAH during constant infusion and the split of renal function was evaluated......Renal blood flow (RBF) was measured in 9 patients with chronic impaired kidney function using MR velocity mapping and compared to PAH clearance and 99mTc-DTPA scintigraphy. An image plane suitable for flow measurement perpendicular to the renal arteries was chosen from 2-dimensional MR angiography...

  13. Experimental Measurement, Analysis and Modelling of Dependency ...

    African Journals Online (AJOL)

    We propose a direct method of measurement of the total emissivity of opaque samples on a range of temperature around the ambient one. The method rests on the modulation of the temperature of the sample and the infra-red signal processing resulting from the surface of the sample we model the total emissivity obtained ...

  14. Endovascular Coil Embolization of Segmental Arteries Prevents Paraplegia After Subsequent TAAA Repair – An Experimental Model

    Science.gov (United States)

    Geisbüsch, S; Stefanovic, A; Koruth, JS; Lin, HM; Morgello, S; Weisz, DJ; Griepp, RB; Di Luozzo, G

    2013-01-01

    Objective To test a strategy for minimizing ischemic spinal cord injury (SCI) following extensive thoracoabdominal aneurysm (TAAA) repair, we occluded a small number of segmental arteries (SAs) endovascularly one week before simulated aneurysm repair in an experimental model. Methods 30 juvenile Yorkshire pigs (25.2±1.7kg) were randomized into three groups. All SAs—intercostal and lumbar—were sacrificed by a combination of surgical ligation of the lumbar SAs and occlusion of intercostal SAs with thoracic endovascular stent grafting (TEVAR). 7–10 days before this simulated TAAA replacement, SAs in the lower thoracic/upper lumbar region were occluded using embolization coils: 1.5±0.5 SAs in Group 1 (T13/L1), and 4.5±0.5 in Group 2 (T11-L3). No SAs were coiled in the controls. Hind limb function was evaluated blindly from daily videotapes using a modified Tarlov score: 0=paraplegia; 9=full recovery. After sacrifice, each segment of spinal cord was graded histologically using the 9-point Kleinman score: 0=normal, 8=complete necrosis. Results Hind limb function remained normal after coil embolization. After simulated TAAA repair, paraplegia occurred in 6/10 control pigs, but only 2/10 pigs in Group 1: no pigs in Group 2 had SCI. Tarlov scores were significantly better in Group 2 (Control vs 1 p=0.06; Control vs 2 p= 0.0002; 1 vs 2 p=0.05). A dramatic reduction in histologic damage—most prominently in the coiled region—was seen when SAs were embolized before simulated TAAA repair. Conclusions Endovascular coiling of 2–4 SAs prevents paraplegia in an experimental model of extensive hybrid TAAA repair, and helps protect the spinal cord from ischemic histopathological injury. A clinical trial in a selected patient population at high risk for postoperative SCI may be appropriate. PMID:24220154

  15. Endothelin receptor mediated Ca(2+) signaling in coronary arteries after experimentally induced ischemia/reperfusion injury in rat

    DEFF Research Database (Denmark)

    Kristiansen, Sarah Brøgger; Haanes, Kristian A.; Sheykhzade, Majid

    2017-01-01

    BACKGROUND: Acute myocardial infarction is one of the leading causes of death. It is caused by a blockage of a coronary artery leading to reduced blood flow to the myocardium and hence ischemic damage. In addition, a second wave of damage after the flow has been restored, named reperfusion injury...... greatly exacerbate the damage. For the latter, no medical treatment exist. In this study the aim was to characterize Ca(2+) sensitivity in coronary arteries following experimental ischemia/reperfusion injury. METHODS: Arteries were isolated from hearts exposed to a well-established rat ischemia...... a phenotypical shift, which includes increased evoked ETB induced contraction in the smooth muscle cell, and also a higher basal tone development which both are dependent on Ca(2+) influx through VGCCs. This is combined with alterations in the ETA calcium handling, which has a stronger dependence on Ca(2...

  16. Oscillometric measurement of brachial artery cross-sectional area and its relationship with cardiovascular risk factors and arterial stiffness in a middle-aged male population.

    Science.gov (United States)

    Otsuka, Toshiaki; Munakata, Ryo; Kato, Katsuhito; Kodani, Eitaro; Ibuki, Chikao; Kusama, Yoshiki; Seino, Yoshihiko; Kawada, Tomoyuki

    2013-10-01

    An enlarged arterial diameter is associated with an increased risk for cardiovascular disease. This study examined the relationship of noninvasively measured brachial artery cross-sectional area with cardiovascular risk factors and arterial stiffness in a middle-aged male population. Absolute volumetric changes of the brachial artery were measured with a newly developed oscillometric method during a general health examination in 387 men (mean age: 38±9 years) without known cardiovascular disease. Based on the measurement, the estimated area (eA) of the brachial artery at end-diastole was obtained. Brachial artery volume elastic modulus (VE) and brachial-ankle pulse wave velocity (baPWV) were simultaneously measured as indices of arterial stiffness by the same device. The relationships of eA with cardiovascular risk factors, including age, obesity, hypertension, dyslipidemia, impaired fasting glucose/diabetes mellitus (IFG/DM), hyperuricemia, smoking and their associated continuous variables, as well as VE and baPWV, were examined. Overall, the mean eA was 12.9 ± 2.9 mm². The eA was significantly higher in subjects with obesity, hypertension or IFG/DM than in those without each of these risk factors. In a multiple linear regression analysis, body mass index (β=0.31, P<0.001), age (β=0.25, P<0.001), systolic blood pressure (β=0.16, P=0.004) and pulse rate (β=-0.13, P=0.005) were independent determinants of eA. In contrast, neither VE nor baPWV were selected as independent determinants of eA. In conclusion, enlarged brachial artery cross-sectional area was significantly associated with cardiovascular risk factors such as age, body mass index and systolic blood pressure, but it was not associated with increased arterial stiffness.

  17. Accurate perioperative flow measurement of the portal vein and hepatic and renal artery: A role for preoperative MRI?

    Energy Technology Data Exchange (ETDEWEB)

    Vermeulen, Mechteld A.R., E-mail: mar.vermeulen@vumc.nl [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Ligthart-Melis, Gerdien C., E-mail: g.ligthart-melis@vumc.nl [Department of Internal Medicine, Dietetics and Nutritional Sciences, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Buijsman, René, E-mail: renebuysman@gmail.com [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Siroen, Michiel P.C., E-mail: m.siroen6@upcmail.nl [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Poll, Marcel C.G. van de, E-mail: mcg.vandepoll@ah.unimaas.nl [Department of Surgery, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht (Netherlands); Boelens, Petra G., E-mail: p.boelens@mumc.nl [Department of Surgery, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht (Netherlands); Dejong, Cornelis H.C., E-mail: chc.dejong@mumc.nl [Department of Surgery, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht (Netherlands); Schaik, Cors van, E-mail: c.vanschaik@vumc.nl [Department of Radiology, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Hofman, Mark B.M., E-mail: mbm.hofman@vumc.nl [Department of Physics and Medical Technology, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Leeuwen, Paul A.M. van, E-mail: pam.vleeuwen@vumc.nl [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands)

    2012-09-15

    Background: Quantification of abdominal blood flow is essential for a variety of gastrointestinal and hepatic topics such as liver transplantation or metabolic flux measurement, but those need to be performed during surgery. It is not clear whether Duplex Doppler Ultrasound during surgery or MRI before surgery is the tool to choose. Objective: To examine whether preoperative evaluation of abdominal blood flow using MRI could prove to be a useful and reliable alternative for the perioperative sonographic approach. Methods: In this study portal and renal venous flow and hepatic arterial flow were sequentially quantified by preoperative MRI, preoperative and perioperative Duplex Doppler Ultrasound (DDUS). 55 Patients scheduled for major abdominal surgery were studied and methods and settings were compared. Additionally, average patient population values were compared. Results: Mean (±SD) plasmaflow measured by perioperative DDUS, preoperative DDUS and MRI, respectively was 433 ± 200/423 ± 162/507 ± 96 ml/min (portal vein); 96 ± 70/74 ± 41/108 ± 91 ml/min (hepatic artery); 248 ± 139/201 ± 118/219 ± 69 ml/min (renal vein). No differences between the different settings of DDUS measurement were detected. Equality of mean was observed for all measurements. Bland Altman Plots showed widespread margins. Hepatic arterial flow measurements correlated with each other, but portal and renal venous flow correlations were absent. Conclusions: Surgery and method (DDUS vs. MRI) do not affect mean flow values. Individual comparison is restricted due to wide range in measurements. Since MRI proves to be more reliable with respect to inter-observer variability, we recommend using mean MRI results in experimental setups.

  18. Blood oxygenation measurements by multichannel reflectometry on the venous and arterial structures of the retina.

    Science.gov (United States)

    Vucea, Valentina; Bernard, Pierre-Jean; Sauvageau, Patrick; Diaconu, Vasile

    2011-09-10

    The aim of the present study was to propose a model and a method to derive the oxyhemoglobin blood content in the retinal veins and arteries by full spectrum reflectometry measurements in the spectral zone from 430 to 680 nm. We proposed a mathematical equation expressed as a linear combination of two terms S(OHb)(λ) and S(Hb)(λ) representing the normalized spectral absorption functions of the hemoglobin and the oxyhemoglobin, one term λ(-n) representing the ocular media absorption with scattering, and a family of multi-Gaussian functions, which usefully compensate for the noncompatibility of the model and the experimental data in the red spectral zone. The present paper suggests that the spectral reflection function in the area from 520 to 580 nm is optimal in calculating the oxyhemoglobin concentration of the blood contained in the endothelial structures of retinal vessels. The model calculation needs a function (1/λ)(-n) that corrects for the ocular media absorption and light scattering on the vessels' structures. For the spectral area of lights with wavelength larger than 580 nm, the reflected light represents mainly the light scattering on the red blood cells.

  19. Arterial wall metabolism in experimental hypertension of coarctation of the aorta of short duration

    Science.gov (United States)

    Hollander, William; Kramsch, Dieter M.; Farmelant, Melvin; Madoff, Irving M.

    1968-01-01

    Coarctation of the mid-thoracic aorata was surgically produced in mongrel dogs which were sacrificed from 4-12 wk after the operation. As compared to the findings in control animals, the sodium, chloride, and water content of the hypetensive portion of the coarcted thoracic aorta was significantly elevated, whereas the electrolyte and water content of the relatively normotensive portion of the coarcted aorta was normal. The sodium, potassium, and water content of the pulmonary artery, skeletal muscle, and cardiac muscle of the coarcted dog was not altered. These observations suggest that an elevated arterial pressure may influence the electrolyte and water composition of the arteries. The arterial pressure also may influence the content and synthesis of acid mucopolysaccharides (MPS) in the arteries since the content of sulfated MPS and the incorporation of injected radiosulfate into sulfated MPS were significantly increased in the hypertensive portion of the coarcted thoracic aorta but were significantly reduced in the relatively normotensive (“hypotensive”) portion of the coarcted aorta. The observed increase in MPS may have been a factor directly responsible for the increase in the sodium content of the hypertensive aorta since MPS can act as polyelectrolytes and bind cations. Although the arterial pressure may influence certain metabolic functions in the arteries, it did not appear to have a direct effect on the arterial lipids since the lipid content of the hypertensive and of the relatively normotensive portions of the coarcted aorta were comparable to the values found in the normal aorta. Images PMID:5645864

  20. Indirect measurement of arterial blood pressure: physiotherapists’ theoretical knowledge

    Directory of Open Access Journals (Sweden)

    Marcelle Morgana Vieira de Assis

    2003-12-01

    Full Text Available Blood pressure checking and its theoretical knowledge are crucial to obtain reliable data in clinical examination. Although it is considered a simple technique to be learned and applied, it is not fully dealt with at physiotherapy university courses. Therefore, a wide range of mistakes and misinterpretations are likely to threaten treatment quality. This work aims to evaluate the theory background of physiotherapists for blood pressure measurement. From June to October 2002, 55 physiotherapists answered a 20- question multiple-choice questionnaire on general knowledge related to concepts, anatomy and physiology, suitable equipment, indirect measurement, blood pressure values, mistakes and misinterpretation factors related to blood pressure measurement. The results disclose faulty theory concepts in the sample studied, indicating the need of deeper approach to this complex theme during course and ongoing updating of professionals.

  1. Experimental measurements of the Hugoniot of stishovite

    Energy Technology Data Exchange (ETDEWEB)

    Furnish, M.D. [Sandia National Labs., Albuquerque, NM (United States). Experimental Impact Physics Dept.; Ito, Eichi [Okayama Univ. (Japan). Inst. for Study of the Earth`s Interior

    1995-10-01

    The crust and mantle of the Earth are primarily composed of silicates. The properties of these materials under compression are of interest for deducing deep-earth composition. As well, the properties of these materials under shock compression are of interest for calculating groundshock propagation. The authors have synthesized, characterized, and performed Hugoniot measurements on monolithic polycrystalline SiO{sub 2} samples which were predominantly stishovite (a high-pressure polymorph). Synthesis was accomplished in a multianvil press with pyrophyllite gaskets and carbon heaters. The samples had densities ranging from 3.80 to 4.07, corresponding to stishovite volume fractions of 0.7 to 0.87, a range confirmed by NMR analysis. Electron microprobe and X-ray fluorescence characterizations showed minor carbon contamination (< 1%), with no other significant impurities. Samples {approximately} 1 mm thick and 3 mm diameter were tested in reverse and forward-ballistics modes on a two-stage light gas gun, using velocity interferometry diagnostics. Impact velocities ranged from 4.0 to 6.5 km/sec. Hugoniot stresses for four tests ranged from 65 to 225 GPa. At higher stresses significant uncertainties arise due to impact tilt/nonplanarity issues. Results are consistent with earlier predictions of the stishovite Hugoniot based on quartz-centered Hugoniot data, static-compression (diamond-anvil cell) data and hydrostatic multianvil cell data. Release behavior appears to be frozen. These results are remarkable in view of the small size of the samples used. Results are compared with current EOS models.

  2. Healing of ulcers on the feet correlated with distal blood pressure measurements in occlusive arterial disease

    DEFF Research Database (Denmark)

    Holstein, P; Lassen, N A

    1980-01-01

    The frequency of healing in subchronic ulcers in 66 feet in 62 patients with arterial occlusive disease was correlated with the systolic digital blood pressure (SDBP) and the systolic ankle blood pressure (SABP), both measured with a strain gauge, and with the skin perfusion pressure on the heel ...

  3. VIP and endothelin receptor antagonist: An effective combination against experimental pulmonary arterial hypertension

    Directory of Open Access Journals (Sweden)

    Szema Anthony M

    2011-10-01

    Full Text Available Abstract Background Pulmonary Arterial Hypertension (PAH remains a therapeutic challenge, and the search continues for more effective drugs and drug combinations. We recently reported that deletion of the vasoactive intestinal peptide (VIP gene caused the spontaneous expression of a PH phenotype that was fully corrected by VIP. The objectives of this investigation were to answer the questions: 1 Can VIP protect against PH in other experimental models? and 2 Does combining VIP with an endothelin (ET receptor antagonist bosentan enhance its efficacy? Methods Within 3 weeks of a single injection of monocrotaline (MCT, s.c. in Sprague Dawley rats, PAH developed, manifested by pulmonary vascular remodeling, lung inflammation, RV hypertrophy, and death within the next 2 weeks. MCT-injected animals were either untreated, treated with bosentan (p.o. alone, with VIP (i.p. alone, or with both together. We selected this particular combination upon finding that VIP down-regulates endothelin receptor expression which is further suppressed by bosentan. Therapeutic outcomes were compared as to hemodynamics, pulmonary vascular pathology, and survival. Results Treatment with VIP, every other day for 3 weeks, begun on the same day as MCT, almost totally prevented PAH pathology, and eliminated mortality for 45 days. Begun 3 weeks after MCT, however, VIP only partially reversed PAH pathology, though more effectively than bosentan. Combined therapy with both drugs fully reversed the pathology, while preventing mortality for at least 45 days. Conclusions 1 VIP completely prevented and significantly reversed MCT-induced PAH; 2 VIP was more effective than bosentan, probably because it targets a wider range of pro-remodeling pathways; and 3 combination therapy with VIP plus bosentan was more effective than either drug alone, probably because both drugs synergistically suppressed ET-ET receptor pathway.

  4. A pitfall in the measurement of arterial blood pressure in the ischaemic limb during elevation

    DEFF Research Database (Denmark)

    Bülow, J; Jelnes, Rolf

    1987-01-01

    In order to evaluate if elevation of the ischaemic limb above heart level is an alternative to the conventionally applied method with external counterpressure for estimation of skin perfusion pressure, femoral and popliteal artery pressures were measured directly in eight patients with occlusion...... arterial pressure decreased only by 20% of the value expected from the degree of elevation of the calf above the level of the heart. Thus, it could be calculated that calf vascular resistance increased two- to three-fold on average during elevation. Four patients were reexamined with the venous pressure...... kept at 10 mmHg during elevation. In these patients, the increase in vascular resistance was significantly less compared with the situation in which venous pressure was 0 mmHg during elevation. The arterial pressure still did not decrease. It is concluded that perfusion pressure in the ischaemic lower...

  5. Measuring FMD in the brachial artery: how important is QRS gating?

    Science.gov (United States)

    Kizhakekuttu, Tinoy J; Gutterman, David D; Phillips, Shane A; Jurva, Jason W; Arthur, Emily I L; Das, Emon; Widlansky, Michael E

    2010-10-01

    Recommendations for the measurement of brachial flow-mediated dilation (FMD) typically suggest images be obtained at identical times in the cardiac cycle, usually end diastole (QRS complex onset). This recommendation presumes that inter-individual differences in arterial compliance are minimized. However, published evidence is conflicting. Furthermore, ECG gating is not available on many ultrasound systems; it requires an expensive software upgrade or increased image processing time. We tested whether analysis of images acquired with QRS gating or with the more simplified method of image averaging would yield similar results. We analyzed FMD and nitroglycerin-mediated dilation (NMD) in 29 adults with type 2 diabetes mellitus and in 31 older adults and 12 young adults without diabetes, yielding a range of brachial artery distensibility. FMD and NMD were measured using recommended QRS-gated brachial artery diameter measurements and, alternatively, the average brachial diameters over the entire R-R interval. We found strong agreement between both methods for FMD and NMD (intraclass correlation coefficients = 0.88-0.99). Measuring FMD and NMD using average diameter measurements significantly reduced post-image-processing time (658.9 ± 71.6 vs. 1,024.1 ± 167.6 s for QRS-gated analysis, P FMD and NMD measurements based on average diameter measurements can be performed without reducing accuracy. This finding may allow for simplification of FMD measurement and aid in the development of FMD as a potentially useful clinical tool.

  6. A study on the pathogenesis of equine sesamoiditis: the effects of experimental occlusion of the sesamoidean artery.

    Science.gov (United States)

    Cornelissen, B P M; Rijkenhuizen, A B M; Buma, P; Barneveld, A

    2002-06-01

    In this study the potential role of circulatory disturbances in the pathogenesis of sesamoiditis was investigated by studying the clinical and histological effects of experimental occlusion of the sesamoidean artery, which is the main nutrient artery of the proximal sesamoid bone (PSB). For this purpose, five adult Dutch Warmblood horses were used in which the sesamoidean artery was occluded with polyvinyl alcohol foam particles. Bone labelling was carried out with oxytetracycline and calcein. All animal were checked clinically three times a week and radiographically at days 14, 21, 28 and 35. At day 35 the animals were killed and the fetlock was dissected and macroscopically evaluated. The PSBs were isolated and radiographed and the soft tissues adjacent to the abaxial side of the PSBs were histologically examined [routine histology and for the neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP)]. The PSBs were divided into bony slices which were radiographed and evaluated histologically (routine, SP, CGRP, fluorescence). All horses showed a slight lameness that gradually diminished. Radiographically enlarged vascular channels were seen in only one horse. Histological data showed that on average 60% (range 37-89%) of the total area had been deprived of vascularization. In two horses an increase in the extent of the arterial network from the basal side of the PSB was seen. Only in the horse with the greatest extent of occlusion were bone necrosis and a reactively increased uptake of fluorochromes adjacent to the occluded arteries found. Bone density did not change. The distribution of neuropeptides in the surrounding soft tissues was not affected by the occlusion. From this study, it can be concluded that a large part of the arterial supply to the PSB can be interrupted without provoking histological and/or radiographic changes that are consistent with clinical sesamoiditis. Therefore, it seems very improbable that circulatory disturbances are

  7. Endovascular coil embolization of segmental arteries prevents paraplegia after subsequent thoracoabdominal aneurysm repair: an experimental model.

    Science.gov (United States)

    Geisbüsch, Sarah; Stefanovic, Angelina; Koruth, Jacob S; Lin, Hung-Mo; Morgello, Susan; Weisz, Donald J; Griepp, Randall B; Di Luozzo, Gabriele

    2014-01-01

    To test a strategy for minimizing ischemic spinal cord injury after extensive thoracoabdominal aneurysm (TAAA) repair, we occluded a small number of segmental arteries (SAs) endovascularly 1 week before simulated aneurysm repair in an experimental model. Thirty juvenile Yorkshire pigs (25.2 ± 1.7 kg) were randomized into 3 groups. All SAs, both intercostal and lumbar, were killed by a combination of surgical ligation of the lumbar SAs and occlusion of intercostal SAs with thoracic endovascular stent grafting. Seven to 10 days before this simulated TAAA replacement, SAs in the lower thoracic/upper lumbar region were occluded using embolization coils: 1.5 ± 0.5 SAs in group 1 (T13/L1), and 4.5 ± 0.5 SAs in group 2 (T11-L3). No SAs were coiled in the controls. Hind limb function was evaluated blindly from daily videotapes using a modified Tarlov score (0 = paraplegia, 9 = full recovery). After death, each segment of spinal cord was graded histologically using the 9-point Kleinman score (0 = normal, 8 = complete necrosis). Hind limb function remained normal after coil embolization. After simulated TAAA repair, paraplegia occurred in 6 of 10 control pigs, but in only 2 of 10 pigs in group 1; no pigs in group 2 had a spinal cord injury. Tarlov scores were significantly better in group 2 (control vs group 1, P = .06; control vs group 2, P = .0002; group 1 vs group 2, P = .05). A dramatic reduction in histologic damage, most prominently in the coiled region, was seen when SAs were embolized before simulated TAAA repair. Endovascular coiling of 2 to 4 SAs prevented paraplegia in an experimental model of extensive hybrid TAAA repair, and helped protect the spinal cord from ischemic histopathologic injury. A clinical trial in a selected patient population at high risk for postoperative spinal cord injury may be appropriate. Copyright © 2014 The American Association for Thoracic Surgery. All rights reserved.

  8. [Multidetector-row CT evaluation of acute bowel ischemia induced by embolization of superior mesenteric artery in experimental porcine models].

    Science.gov (United States)

    Qiang, Jin-wei; Li, Ruo-kun; Feng, Xiao-yuan; Liao, Zhi-he; He, Cheng; Feng, Qin; Zhang, Biao; Ye, Xuan-guang

    2010-02-01

    To evaluate the application of multi-detector row CT (MDCT) and CT angiography (CTA) for detecting early signs of acute bowel ischemia (ABI) in experimental porcine models. Twelve pigs were assigned to four groups with 3 in each group. The digital subtraction angiography of superior mesenteric artery (SMA) and the embolization of branches of SMA with gelatin sponge and blood clot were performed by percutaneous transfemoral artery puncture and catheterization. MDCT pre- and post-contrast scanning in the arterial, venous and delay phase and CTA with three-dimensional reconstruction were carried out at pre-operation, 3 h, 6 h, 9 h, and 12 h after occlusion. The normal mesenteric vascular anatomy, arterial occlusion, mesentery and bowel changes, and dynamic change were evaluated. ABI changes were identified pathologically in all the 12 experimental pigs, and the severity of ischemia increased over time after embolization. CTA showed all 57 embolized branches of SMA and 29 of 34 unoccluded arterial branches with 5 false-positive vessel occlusions. The sensitivity and specificity of CTA were 100% and 85.3%, respectively. Thin-slab maximum intensity projection (TSMIP) revealed the disappearance of distal comb-like vessel branches and brush-like vasa recta, which were clearly delineated in the normal bowel segments. Using this criterion, TSMIP correctly defined 23 of 24 ischemic bowel segments and all the 12 normal bowel segments with a sensitivity of 95.8% and a specificity of 100%. MDCT and CTA reliably define normal and occluded mesenteric vessels in the pig. It can easily detect ischemic bowel segment by identified early changes of ischemia. The early direct ischemic signs are occluded vessels, the disappearance of distal comb-like branches or brush-like vasa recta, and poor bowel enhancement. The early indirect sign is bowel dilatation with fluid collection.

  9. Development of a Tonometric Sensor with a Decoupled Circular Array for Precisely Measuring Radial Artery Pulse

    Directory of Open Access Journals (Sweden)

    Min-Ho Jun

    2016-05-01

    Full Text Available The radial artery pulse is one of the major diagnostic indices used clinically in both Eastern and Western medicine. One of the prominent methods for measuring the radial artery pulse is the piezoresistive sensor array. Independence among channels and an appropriate sensor arrangement are important for effectively assessing the spatial-temporal information of the pulse. This study developed a circular-type seven-channel piezoresistive sensor array using face-down bonding (FDB as one of the sensor combination methods. The three-layered housing structure that included independent pressure sensor units using the FDB method not only enabled elimination of the crosstalk among channels, but also allowed various array patterns to be created for effective pulse measurement. The sensors were arranged in a circular-type arrangement such that they could estimate the direction of the radial artery and precisely measure the pulse wave. The performance of the fabricated sensor array was validated by evaluating the sensor sensitivity per channel, and the possibility of estimating the blood vessel direction was demonstrated through a radial artery pulse simulator. We expect the proposed sensor to allow accurate extraction of the pulse indices for pulse diagnosis.

  10. Magnetic Resonance Signal Intensity Ratio Measurement Before Uterine Artery Embolization

    DEFF Research Database (Denmark)

    Duvnjak, Stevo; Ravn, Pernille; Green, Anders

    2017-01-01

    PURPOSE: To evaluate whether the magnetic resonance imaging (MRI) signal intensity (SI) ratio between the dominant fibroid and the periphery striated muscle can predict fibroid volume reduction >50% after uterine fibroid embolization (UFE). MATERIALS AND METHODS: From October 2013 until May 2016......, 52 patients were included in this prospective study. The SI ratio before UFE was calculated using circular region of interests placed on the dominant fibroid and the iliac muscle. The SI fibroid-to-iliac muscle ratio was calculated as SI of the dominant fibroid/SI of the iliac muscle on T1-, T2......-, and T1 post-contrast-weighted sequences. The dominant fibroid volume was measured and analyzed before and after UFE. RESULTS: In all, 46 patients who completed the three-month follow-up MRI were available for analysis. The correlation between SI fibroid-to-muscle ratio at the T2-weighted sequence...

  11. Semi-automatic quantitative measurements of intracranial internal carotid artery stenosis and calcification using CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Bleeker, Leslie; Berg, Rene van den; Majoie, Charles B. [Academic Medical Center, Department of Radiology, Amsterdam (Netherlands); Marquering, Henk A. [Academic Medical Center, Department of Radiology, Amsterdam (Netherlands); Academic Medical Center, Department of Biomedical Engineering and Physics, Amsterdam (Netherlands); Nederkoorn, Paul J. [Academic Medical Center, Department of Neurology, Amsterdam (Netherlands)

    2012-09-15

    Intracranial carotid artery atherosclerotic disease is an independent predictor for recurrent stroke. However, its quantitative assessment is not routinely performed in clinical practice. In this diagnostic study, we present and evaluate a novel semi-automatic application to quantitatively measure intracranial internal carotid artery (ICA) degree of stenosis and calcium volume in CT angiography (CTA) images. In this retrospective study involving CTA images of 88 consecutive patients, intracranial ICA stenosis was quantitatively measured by two independent observers. Stenoses were categorized with cutoff values of 30% and 50%. The calcification in the intracranial ICA was qualitatively categorized as absent, mild, moderate, or severe and quantitatively measured using the semi-automatic application. Linear weighted kappa values were calculated to assess the interobserver agreement of the stenosis and calcium categorization. The average and the standard deviation of the quantitative calcium volume were calculated for the calcium categories. For the stenosis measurements, the CTA images of 162 arteries yielded an interobserver correlation of 0.78 (P < 0.001). Kappa values of the categorized stenosis measurements were moderate: 0.45 and 0.58 for cutoff values of 30% and 50%, respectively. The kappa value for the calcium categorization was 0.62, with a good agreement between the qualitative and quantitative calcium assessment. Quantitative degree of stenosis measurement of the intracranial ICA on CTA is feasible with a good interobserver agreement ICA. Qualitative calcium categorization agrees well with quantitative measurements. (orig.)

  12. Serial measurements of high-sensitivity cardiac troponin T after exercise stress test in stable coronary artery disease

    DEFF Research Database (Denmark)

    Axelsson, Anna; Ruwald, Martin Huth; Dalsgaard, Morten

    2013-01-01

    The aim was to assess serial measurements of high-sensitivity cardiac troponin T (hs-cTNT) post-exercise in patients with stable coronary artery disease (CAD).......The aim was to assess serial measurements of high-sensitivity cardiac troponin T (hs-cTNT) post-exercise in patients with stable coronary artery disease (CAD)....

  13. Mortality risk in hemodialysis patients with increased arterial stiffness is reduced by attainment of classical clinical performance measures

    DEFF Research Database (Denmark)

    Scholze, Alexandra; Thies, Christina; Cheikhalfraj, Mohamed

    2009-01-01

    We determined whether attainment of classical clinical performance measures for hemodialysis care improves survival in hemodialysis patients with increased arterial stiffness.......We determined whether attainment of classical clinical performance measures for hemodialysis care improves survival in hemodialysis patients with increased arterial stiffness....

  14. An Ultra Miniature MEMS Capacitor for Arterial Pressure Measurement

    Science.gov (United States)

    Monga, A.; Vig, R.

    2012-12-01

    In biomedical field, there is a need for improving medical technologies to provide accurate diagnosis to patients. The objective is to develop a minimally invasive, implantable, pressure sensing system that continuously monitors physiological changes in real-time. For implementing, three different shapes of MEMS capacitive pressure sensor having same area of diaphragm 0.126 mm² is designed and simulated for blood pressure measurement. The various shapes which are taken are circular, square and rectangular. COMSOL multiphysics tool is used for simulation. For these shapes capacitance and deflection variation of membrane with applied pressure is studied. Result shows a sensitivity of 0.255 aF/kPa, 0.125 aF/kPa and 0.09 aF/kPa for circular, square and rectangular shape, respectively. So, circular MEMS capacitor provides the greater sensitivity than all other shapes and also provides greater deflection of diaphragm due to applied pressure of 40 kPa. Also deflection is more in circular diaphragm capacitive pressure sensor.

  15. Experimental measurements and mathematics; Les mesures experimentales et les mathematiques

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, I.; Bruno, S.; Durand, O.; Gaillard, P.; Lagrange, J.M.; Lamy, F.; Peyrat, J.P. [CEA Bruyeres-le-Chatel, 91 (France); Choux, A.; Druoton, L.; Pascal, G.; Sulpice, F. [CEA Valduc, 21 - Is-sur-Tille (France); Busvelle, E.; Garnier, L. [Universite de Bourgogne, Lab. d' Electronique, Informatique et Image, 21 - Dijon (France); Gauthier, J.P. [Laboratoire des Sciences de l' Information et des Systemes, 83 - Toulon (France); Langevin, R. [Institut Mathematique de Bourgogne, 21 - Dijon (France)

    2011-01-15

    Many problems that appear in experimental works can be solved by using mathematical methods, from the conception phase to the interpretation of measurements. We illustrate the use of these methods at CEA-DAM by pointing out some examples in 3 typical domains: treatment of experimental data, geometrical controls of targets, and analysis of a huge quantity of data. (authors)

  16. Cardiac "fitness" training: an experimental comparative study of three methods of pulmonary artery banding for ventricular training.

    Science.gov (United States)

    Le Bret, Emmanuel; Lupoglazoff, Jean Marc; Borenstein, Nicolas; Fromont, Gaelle; Laborde, François; Bachet, Jean; Vouhé, Pascal

    2005-01-01

    When the left ventricle is unable to sustain a systemic pressure in transposition of the great arteries (TGA), left ventricular retraining is mandatory before the morphologic left ventricle under the aorta is switched. This is currently achieved by creating a ventricular overload through pulmonary artery banding, usually associated with an aortopulmonary shunt in case of a TGA with an intact ventricular septum. Our experimental study compared three different modes of increased ventricular afterload to obtain ventricular hypertrophy. Fifteen lambs (mean weight 48 kg) underwent pulmonary artery banding. Five animals (group I) received a classic band; 5 (group II) received a classic band which was adjusted at week 1 and 3; and 4 (group III) received a band which was tightened for 1 hour, twice a day (early morning and late afternoon). After 5 weeks, the lambs were evaluated hemodynamically before they were sacrificed and their hearts harvested for histologic examination. No difference was noted in the hemodynamic data between groups 1 and II. Group III showed a greater ability to increase ventricular pressure in this model. No significant difference was noted between the three groups in terms of macroscopic alterations, but all animals demonstrated an increase in right ventricular wall thickness compared with control animals. Several fibrosis areas were evident in group I and II but none in group III. Intermittent pulmonary artery banding is able to induce hemodynamically sufficient ventricular hypertrophy without fibrosis.

  17. Quantitative flow measurement after placing a flow diverter for a distal internal carotid artery aneurysm.

    Science.gov (United States)

    Chen, Chien-Wei; Wong, Ho-Fai; Ye, Yu-Ling; Chen, Yao-Liang; Chen, Wei-Liang; Ou, Chang-Hsien; Tsai, Yuan-Hsiung

    2017-12-01

    To evaluate the differences in arterial flow after flow diverter placement using quantitative flow measurements based on digital subtraction angiography (DSA). Between November 2013 and November 2015, all patients who had flow diverters placed for distal internal carotid artery (ICA) aneurysms were reviewed. Patients in whom the stent was placed across the ostia of the ophthalmic artery (OphA) and anterior choroidal artery (AChA) were enrolled. Five regions of interest were selected: the proximal ICA (as a reference), terminal ICA, middle cerebral artery (MCA), anterior cerebral artery (ACA), OphA, and AChA. The values of the peak, time-to-peak (TTP), and area under the curve (AUC) were analyzed using a quantitative DSA technique. The study enrolled 13 patients. The quantitative flow analysis showed improved flow in the terminal ICA (peak and AUC, p=0.036 and p=0.04, respectively), MCA (AUC, p=0.023), and ACA (AUC, p=0.006), and decreased flow in the OphA (peak and AUC, p=0.013 and p=0.005, respectively) and AChA (peak and subtracted TTP, p=0.023 and p=0.050, respectively) after flow diverter placement. Larger aneurysm volume was significantly correlated with decreased OphA flow after the procedure (peak and AUC, p=0.049 and p=0.037, respectively). Larger aneurysm volume also had a marginal correlation with increased distal ICA flow after the procedure, but this did not reach significance (peak and AUC, p=0.195 and p=0.060, respectively). Without using extra contrast medium or radiation dosages, color-coded DSA enables quantitative monitoring of the cerebral circulation after flow-diverting treatment. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  18. Time-resolved PIV measurements of the flow field in a stenosed, compliant arterial model

    Science.gov (United States)

    Geoghegan, P. H.; Buchmann, N. A.; Soria, J.; Jermy, M. C.

    2013-05-01

    Compliant (flexible) structures play an important role in several biological flows including the lungs, heart and arteries. Coronary heart disease is caused by a constriction in the artery due to a build-up of atherosclerotic plaque. This plaque is also of major concern in the carotid artery which supplies blood to the brain. Blood flow within these arteries is strongly influenced by the movement of the wall. To study these problems experimentally in vitro, especially using flow visualisation techniques, can be expensive due to the high-intensity and high-repetition rate light sources required. In this work, time-resolved particle image velocimetry using a relatively low-cost light-emitting diode illumination system was applied to the study of a compliant flow phantom representing a stenosed (constricted) carotid artery experiencing a physiologically realistic flow wave. Dynamic similarity between in vivo and in vitro conditions was ensured in phantom construction by matching the distensibility and the elastic wave propagation wavelength and in the fluid system through matching Reynolds ( Re) and Womersley number ( α) with a maximum, minimum and mean Re of 939, 379 and 632, respectively, and a α of 4.54. The stenosis had a symmetric constriction of 50 % by diameter (75 % by area). Once the flow rate reached a critical value, Kelvin-Helmholtz instabilities were observed to occur in the shear layer between the main jet exiting the stenosis and a reverse flow region that occurred at a radial distance of 0.34 D from the axis of symmetry in the region on interest 0-2.5 D longitudinally downstream from the stenosis exit. The instability had an axis-symmetric nature, but as peak flow rate was approached this symmetry breaks down producing instability in the flow field. The characteristics of the vortex train were sensitive not only to the instantaneous flow rate, but also to whether the flow was accelerating or decelerating globally.

  19. Experimental study on the appropriate emboilic site during superior mesenteric artery embolization : using coil and gelfoam

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Won; Jin, Gong Yong; Oh, Hee Sul; Lim, Yeong Su; Lee, Sang Yong; Lee, Jeong Min; Kim, Chong Soo; Han, Young Min; Lee, Dong Geun [Chonbuk National Univ. Medical School, Chonju (Korea, Republic of)

    1998-07-01

    To determine the effective embolic material and appropriate embolic site by comparing bowel changes after arterial embolization in dogs in which the proximal or distal level of the superior mesenteric artery had been occluded with gelfoam particles or a coil. Material and Methods : Using the coaxial catheter system,super selective arterial embolization was performed at sixteen sites in four dogs. In groups A and B, each site was occluded at the proximal or distal marginal artery, respectively, with gelfoam particles and in groups C and D, at the proximal or distal artery, respectively, with a coil. All dogs were sacrificed one day after the procedure, and gross and microscopic histologic findings were evaluated. Results : In all dogs, the procedure was successful. In group B, significant mucosal destruction, lymphocyte proliferation in submucosa and mucosa, and diffuse swelling in all layers of the intestine were found at all sites. The vessel in the submucosal layer was completely obstructed by red blood cells and gelfoam.At three sites, the intestine showed diffuse ischemic change, and at one other site, focal ischemic change was observed. In group D, exudation with destruction of mucosa and submucosal hemorrhage occurred at one site, but in groups A and C, intestinal layers were found to be normal. Conclusion :Using a coil, super selective arterial embolization was successful, even up to the distal level of the intestinal artery, and the intestine showed no ischemic change. Embolization with gelfoam must be performed carefully at the proximal level, and since it can cause severe intestinal necrosis, must be avoided at the distal level.

  20. Circle of Willis variations and artery diameter measurements in the Turkish population.

    Science.gov (United States)

    Yeniçeri, I Ö; Çullu, N; Deveer, M; Yeniçeri, E N

    2017-01-01

    The aim of this study was to evaluate the frequency of circle of Willis (COW) variations and the measurements of the COW vessel diameters in the Turkish population. The patient population for this single-centre, retrospective study was formed of patients who had brain magnetic resonance angiography (MRA). A total of 384 subjects were included in the study. The three-dimensional time-of-flight (TOF) technique was used for MRA imaging to evaluate the anatomy of the COW. Variations in the COW were recorded. The diameters of the critical arteries of the COW were measured. Adult configuration of the COW was determined in 326 (85%) cases, foetal configuration in 50 (13%) cases and transitional configuration in 8 (2%) cases. The COW was normal in 328 (85.4%). In the remaining 56 (14.6%) cases, agenesis was determined in 62 vessels. The mean calibrations of the vessels were measured as 2.85 mm in the basilar artery, 4.24 mm in the right internal carotid artery (ICA), 4.32 mm in the left ICA, 1.58 mm in the right A1, 1.64 mm in the left A1, 2.13 mm in the right M1, 2.10 mm in the left M1, 1.80 mm in the right P1, 1.88 mm in the left P1, 1.12 mm in the right posterior communicating artery, and 1.12 mm in the left posterior communicating artery. Circle of Willis variations may show geographic and ethnic differences. Knowledge of the frequency and types of variation in the population is important for neurosurgeons and in radiological interventional procedures as a guide for entry and in respect of collateral which could develop later.

  1. Oscillometric measurement of arterial pulse pressure for patients supported by a rotary blood pump.

    Science.gov (United States)

    Yu, Yih-Choung; Peterson, Anna

    2015-01-01

    A computer model has been developed to evaluate the accuracy of an oscillometric method to measure the arterial pulse pressure from a patient with a rotary ventricular assist device (VAD). This computer model consists of three major components: the cardiovascular system, the HeartMate II VAD, and the operation of an automated cuff. Simulation was performed to mimic failure, recovery, and normal cardiac functions of a patient, supported by the HeartMate II VAD at different levels from minimum to maximum. The oscillating cuff pressure, simulating the air pressure of a deflecting cuff, was obtained from simulation under different conditions to test the accuracy of an oscillometric algorithm in determining the arterial pulse pressure. The algorithm was able to detect the systolic and diastolic arterial pressure with the error within ±2 mmHg in most cases, except the cases when ventricular suction, induced by the VAD, occurred. The results from this study suggested that the oscillometric algorithm is capable to accurately detect the arterial pulse pressure for a rotary VAD patient if the algorithm is properly tuned.

  2. A cell culture model using rat coronary artery adventitial fibroblasts to measure collagen production

    Directory of Open Access Journals (Sweden)

    Meszaros Gary

    2007-05-01

    Full Text Available Abstract Background We have developed a rat cell model for studying collagen type I production in coronary artery adventitial fibroblasts. Increased deposition of adventitial collagen type I leads to stiffening of the blood vessel, increased blood pressure, arteriosclerosis and coronary heart disease. Although the source and mechanism of collagen deposition is yet unknown, the adventitia appears to play a significant role. To demonstrate the application of our cell model, cultured adventitial fibroblasts were treated with sex hormones and the effect on collagen production measured. Methods Hearts (10–12 weeks were harvested and the left anterior descending coronary artery (LAD was isolated and removed. Tissue explants were cultured and cells (passages 2–4 were confirmed as fibroblasts using immunohistochemistry. Optimal conditions were determined for cell tissue harvest, timing, proliferation and culture conditions. Fibroblasts were exposed to 10-7 M testosterone or 10-7 M estrogen for 24 hours and either immunostained for collagen type I or subjected to ELISA. Results Results showed increased collagen staining in fibroblasts treated with testosterone compared to control and decreased staining with estrogen. ELISA results showed that testosterone increased collagen I by 20% whereas estrogen decreased collagen I by 15%. Conclusion Data demonstrates the usefulness of our cell model in studying the specific role of the adventitia apart from other blood vessel tissue in rat coronary arteries. Results suggest opposite effects of testosterone and estrogen on collagen synthesis in the rat coronary artery adventitial fibroblasts.

  3. Comparison of ultrasonic Doppler flow monitor, oscillometric, and direct arterial blood pressure measurements in ill dogs.

    Science.gov (United States)

    Bosiack, Ann P; Mann, F A; Dodam, John R; Wagner-Mann, Colette C; Branson, Keith R

    2010-04-01

    To compare blood pressure measurements obtained via ultrasonic Doppler flow monitor (DOP) and 2 oscillometric noninvasive blood pressure monitors (CAR and PAS) to invasive blood pressure (IBP) in hospitalized, conscious dogs with a range of blood pressures. Prospective clinical study. University teaching hospital. Eleven client-owned dogs aged between 4 months and 11.5 years (median 6 y), and weighing between 5.8 and 37.5 kg (median 30.2 kg). Blood pressure measurement. Three consecutive measurements of systolic, diastolic, and mean arterial pressure (MAP) were recorded for each of the 3 indirect devices (only systolic for DOP), along with concurrent IBP measurements. The data were categorized into 3 groups: hypotensive (direct MAPor=100 mm Hg), and hypertensive (direct MAP>100 mm Hg). Each indirect method was compared with the corresponding direct arterial pressure using the Bland-Altman method. Within the hypotensive group, each indirect method overestimated the corresponding IBP. Within the normotensive group all indirect systolic measurements and the PAS diastolic measurements underestimated the corresponding IBP. The remaining indirect measurements overestimated the corresponding IBP. Within the hypertensive group, DOP and CAR systolic measurements underestimated the corresponding IBP, and the remaining indirect measurements overestimated the corresponding IBP. In hypertensive dogs oscillometric systolic measurements were more accurate than MAP. In hypotensive dogs MAP measurements were more accurate than systolic measurements. All indirect measurements were most accurate in hypertensive dogs. The noninvasive blood pressure monitors in our study did not meet the validation standards set in human medicine. However, CAR diastolic and MAP measurements within the normotensive group, CAR MAP measurements within the hypertensive group, and PAS diastolic measurements in all groups were close to these standards. All indirect measurements showed greater bias during

  4. Coronary flow reserve and relative flow reserve measured by N-13 ammonia PET for characterization of coronary artery disease.

    Science.gov (United States)

    Cho, Sang-Geon; Park, Ki Seong; Kim, Jahae; Kang, Sae-Ryung; Song, Ho-Chun; Kim, Ju Han; Cho, Jae Yeong; Hong, Young Joon; Jabin, Zeenat; Park, Hee Jeong; Jeong, Geum-Cheol; Kwon, Seong Young; Paeng, Jin Chul; Kim, Hyeon Sik; Min, Jung-Joon; Garcia, Ernest V; Bom, Henry Hee-Seung

    2017-02-01

    We evaluated the relationships between coronary flow reserve (CFR) and relative flow reserve (RFR) measured by N-13 ammonia positron emission tomography (PET) for characterization of epicardial coronary artery disease (CAD). Sixty-nine consecutive stable angina patients underwent N-13 ammonia PET, coronary computed tomography angiography (CCTA), and if necessary, invasive coronary angiography (CAG) within 2 weeks. Myocardial blood flow (MBF), CFR, RFR, and coronary vascular resistance of the reference arterial territory (CVR ref ) were measured by N-13 ammonia PET. The presence of significant stenosis (SS) and diffuse atherosclerosis (DA) was evaluated on CCTA and CAG. Functional parameters measured by PET were compared among arteries with and without SS and DA. Arteries with SS and those with DA showed significantly lower stress MBF, as compared to those without. RFR was significantly lower in arteries with SS as compared to those without, while CFR was not. CFR was significantly lower in arteries with DA as compared to those without, while RFR was not. Among arteries without SS, CFR was significantly lower in those with DA as compared to those without. However, among arteries with SS, CFR was similar between those with and without DA. In contrast, RFR was significantly lower in arteries with SS, regardless of the presence of DA. CFR and RFR showed a weak positive correlation (r = 0.269) with discordance in 24 cases (35%). Among the arteries with CFR-RFR discordance, the prevalence of DA was significantly higher in those with low CFR but preserved RFR, as compared to those with preserved CFR but low RFR (75 vs 25%, p = 0.028). CVR ref was significantly higher in arteries with DA, implicating a correlation of DA with underlying microvascular disease. CFR and RFR measured by myocardial perfusion PET could provide a comprehensive information for characterization of epicardial CAD.

  5. Measuring and Analyzing the Scholarly Impact of Experimental Evaluation Initiatives

    DEFF Research Database (Denmark)

    Angelini, Marco; Ferro, Nicola; Larsen, Birger

    2014-01-01

    Evaluation initiatives have been widely credited with contributing highly to the development and advancement of information access systems, by providing a sustainable platform for conducting the very demanding activity of comparable experimental evaluation in a large scale. Measuring the impact......, a methodology for measuring their scholarly impact, and tools exploiting visual analytics to analyze the outcomes....

  6. Measurement of the arterial concentration of Gd-DTPA using MRI: a step toward quantitative perfusion imaging

    DEFF Research Database (Denmark)

    Fritz-Hansen, T; Rostrup, Egill; Larsson, H B

    1996-01-01

    A noninvasive method using an inversion recovery turbo-FLASH for dynamic measurement of the arterial input function represented by the bolus passage of Gd-DTPA in the descending aorta is presented, and the results are compared with the input function obtained by arterial blood samples. A good acc...

  7. A Simplified Quantitative Method to Measure Brain Shifts in Patients with Middle Cerebral Artery Stroke.

    Science.gov (United States)

    Paletta, Nina; Maali, Laith; Zahran, Abdurrehman; Sethuraman, Sankara; Figueroa, Ramon; Nichols, Fenwick T; Bruno, Askiel

    2017-11-10

    A standardized and validated method to measure brain shifts in malignant middle cerebral artery (MCA) stroke with decompressive hemicraniectomy (DHC) could facilitate clinical decision making, prognostication, and comparison of results between studies. We tested for reliability simplified methods to measure transcalvarial herniation, midline brain shift, and the contralateral cerebral ventricular atrium in malignant MCA stroke after DHC. Multiple raters measured brain shifts on post-DHC computed tomography (CT) scans with aligned and unaligned slice orientations in 25 patients. We compared the simplified measurements to previously reported more meticulous measurements. The simplified measurements correlate well with the more meticulous measurements on both aligned and unaligned CTs (intraclass correlation coefficients .72-.89). These simplified and expedient methods of measuring brain shifts in malignant MCA stroke after DHC correlate well with the more meticulous methods. Copyright © 2017 by the American Society of Neuroimaging.

  8. A comparison of basilar artery diameters measured by T2WI and TOF MR angiography.

    Science.gov (United States)

    Çelebioğlu, Emre Can; Aldur, Muhammed Mustafa; Tunali, Selcuk; Hayran, Murvet; Taşçıoğlu, Ayşe Beliz; Sargon, F Mustafa

    2017-11-01

    The purpose of our study is to compare basilar artery diameters (BAD) measured by T2WI to diameters measured by TOF MR angiography (MRA). By doing this, we hope to understand how compatible these two methodologies are with each other. We used data from 100 patients (59 females, 41 males) who underwent a session of both T2W MRI and TOF MRA at the same time (ages between 18 and 83). We measured BAD by both T2WI and TOF MRA in three different levels. We then compared these diameters measured by two different methodologies to each other. In an area between the vertebrobasilar junction and posterior cerebral artery, all data measured by T2WI and TOF MRA in three different levels were analyzed. Average diameters measured by T2WI and TOF MRA turned out to be 79.5% correlated with each other. As a result of our mathematical model that we came up with through regression analysis, we calculated that measurements taken by T2WI on mid-pontine levels could predict TOF MRA measures with 78.3% accuracy. In T2WI and TOF MRA, average diameters measured were 2.982 ± 0.4717 and 3.205 ± 0.4281 mm, respectively. Statistical analyses showed that images measured by T2W series were significantly smaller than those measured by TOF MRA (p < 0.05). Our study showed that BAD measured by T2WI were smaller than those measured by TOF MRA. We think that it will be beneficial to refer our results to avoid T2WI and TOF MRA mismatch when evaluating BAD.

  9. Short-Term Effects of Ankaferd Hemostat for Renal Artery Embolization: An Experimental Study

    Energy Technology Data Exchange (ETDEWEB)

    Ozbek, Orhan, E-mail: orhan.ozbek@gmail.com [Selcuk University, Department of Radiology, Meram School of Medicine (Turkey); Acar, Kadir [Selcuk University, Division of Hematology, Department of Internal Medicine, Meram School of Medicine (Turkey); Koc, Osman [Selcuk University, Department of Radiology, Meram School of Medicine (Turkey); Saritas, Kadir [Afyon Kocatepe University, Department of General Surgery, Veterinary Faculty (Turkey); Toy, Hatice [Selcuk University, Department of Pathology, Meram School of Medicine (Turkey); Solak, Yalcin [Selcuk University, Division of Nephrology, Department of Internal Medicine, Meram School of Medicine (Turkey); Ozbek, Seda [Selcuk University, Department of Radiology, Selcuklu School of Medicine (Turkey); Kucukapan, Ahmet; Guler, Ibrahim [Selcuk University, Department of Radiology, Meram School of Medicine (Turkey); Gaipov, Abduzhappar; Turk, Suleyman [Selcuk University, Division of Nephrology, Department of Internal Medicine, Meram School of Medicine (Turkey); Haznedaroglu, Ibrahim Celaleddin [Hacettepe University, Division of Hematology, Department of Internal Medicine, Faculty of Medicine (Turkey)

    2013-04-15

    Renal artery embolization (RAE) is a minimally invasive therapeutic technique that is utilized in a number of disorders. Ankaferd is a novel hemostatic agent with a new mechanism of action independent of clotting factors. We used Ankaferd for RAE in a sheep model. Seven adult female sheep were included in the study. Selective renal arteriogram using 5-F diagnostic catheter was performed to make sure that each kidney was fed by a single renal artery and the animal had normal renal vasculature. Coaxial 2.7-F microcatheter was advanced to the distal main renal artery. Under fluoroscopic guidance, 2 mL of Ankaferd mixed with 2 mL of nonionic iodinated contrast agent was slowly injected. Fluoroscopy was used to observe the deceleration of flow and stagnation. Control renal angiograms were performed just after embolization. After the procedure, the animals were observed for 1 day and then sacrificed with intravenous sodium thiopental. The technical success was observed in seven of the seven animals.. After embolization procedure, none of the animals died or experienced a major systemic adverse event. On macroscopic examination of the embolized kidneys, thrombus at the level of main renal artery formed after Ankaferd embolization was more compact compared with the thrombi that was not Ankaferd-associated, which was observed elsewhere. Microscopically, majority of the renal tubular cells (80-90 %) were necrotic, and there was epithelial cell damage in a small portion of the cells (10-20 %). RAE was safe and effective in the short-term with Ankaferd in studied animals. Further studies should be conducted to better delineate the embolizing potential of this novel hemostatic agent.

  10. Characterizing Methods of Measuring Flow-Mediated Dilation in the Brachial Artery

    Science.gov (United States)

    Callender, Ariane R.

    2010-01-01

    Regulation of vascular tone is one of the many important functions of the vascular endothelium. Endothelial dysfunction is a critical early event in the pathogenesis of atherosclerosis and occurs in the absence of angiographic disease. Flow-Mediated Dilation (FMD) is a noninvasive technique commonly used to evaluate endothelium-dependent vasodilation in humans and gauge the health of the cardiovascular system. Reductions in brachial artery FMD have been strongly correlated with disease progression and are predictive of future cardiac events. The flow stimulus for brachial artery FMD occurs as a result of the increased shear stress following deflation of an occlusion cuff around the upper arm. Using 2-dimensional ultrasound, changes in arterial diameter up to 5-minutes following cuff deflation are calculated from baseline image measurements. Along with pulsed Doppler measures of flow velocity through the artery, flow-mediated, endothelium-dependent vasodilation can be assessed. There is debate among investigators, however, about the proper positioning of the occlusion cuff during FMD testing. It is thought that placement of the cuff around the upper arm may not accurately reflect the impact of nitric oxide, a critically important molecule released as a result of the increased shear stress created by the FMD technique. Data suggest that the production of other endogenous metabolites may also contribute to FMD-related changes when positioning the cuff around the upper arm. To overcome the potential influence of such molecules, researchers now suggest that the occlusion cuff be placed below the elbow allowing a more precise estimate of nitric oxide mediated dilation. The purpose of this study is to compare the differences in FMD between the two methodologies of occlusion cuff placement. In addition, this study will determine the method that is easier for ultrasound technicians to perform and will produce a low coefficient of variance between technicians. Ultimately

  11. Constitutively active form of natriuretic peptide receptor 2 ameliorates experimental pulmonary arterial hypertension.

    Science.gov (United States)

    Nawa, Nobutoshi; Ishida, Hidekazu; Katsuragi, Shinichi; Baden, Hiroki; Takahashi, Kunihiko; Higeno, Ryota; Torigoe, Fumiko; Mihara, Seiko; Narita, Jun; Miura, Kohji; Nakamura, Kazufumi; Kogaki, Shigetoyo; Ozono, Keiichi

    2016-01-01

    We recently found a constitutively active mutant of natriuretic peptide receptor 2 (caNPR2; V883M), which synthesizes larger amounts of cyclic guanosine monophosphate (cGMP) intracellularly without any ligand stimulation than existing drugs. The aim of this study was to investigate the therapeutic effects of gene transduction using caNPR2 for pulmonary arterial hypertension (PAH). In vitro gene transduction into human pulmonary arterial smooth muscle cells using Sendai virus (SeV) vectors carrying caNPR2 induced 10,000-fold increases in the synthesis of cGMP without ligand stimulation, and the proliferation of caNPR2-expressing cells was significantly attenuated. The PAH model rats generated by hypoxia and the administration of SU5416 were then treated with SeV vectors through a direct injection into the left pulmonary artery. Right ventricular systolic pressure was significantly decreased 2 weeks after the treatment, while systemic blood pressure remained unchanged. Histological analyses revealed that the medial wall thickness and occlusion rate of pulmonary arterioles were significantly improved in caNPR2-treated lungs. Neither the systemic integration of virus vectors nor side effects were observed. The massive stimulation of cGMP synthesis by gene therapy with caNPR2 was safe and effective in a PAH rat model and, thus, has potential as a novel therapy for patients with severe progressive PAH.

  12. Pulmonary artery haemorrhage in newborn calves following bluetongue virus serotype 8 experimental infections of pregnant heifers.

    Science.gov (United States)

    Martinelle, Ludovic; Dal Pozzo, Fabiana; Sarradin, Pierre; De Leeuw, Ilse; De Clercq, Kris; Thys, Christine; Thiry, Etienne; Saegerman, Claude

    2013-12-27

    The emergence of bluetongue disease (BT) among livestock in Europe in 2006 raised many questions including the occurrence and epidemiological significance of foetal infections in cattle. To clarify these aspects, vaccinated and unvaccinated pregnant heifers were sequentially infected twice in an isolation facility (biosafety level 3) with a northern European outbreak strain of Bluetongue virus serotype 8 (BTV-8). The study was terminated 2 months after calving with necropsy of the dams and their offspring. The cattle were monitored throughout the study by clinical scoring and for the presence of circulating neutralising antibodies, and after calving for the presence of infectious virus and viral RNA in blood and milk. Four calves, one born from a vaccinated dam and three from non-vaccinated ones, that were infected at 120 days of gestation had obvious haemorrhage of the pulmonary artery at necropsy. Although haemorrhage of the pulmonary artery is highly characteristic of BT, viral RNA was not detected in any of these calves. Furthermore, although none of the calves born from heifers infected prior to mid-gestation had teratogenic BTV typical brain lesions, some had lesions at birth suggestive of in utero BTV infection. Despite the lack of viral RNA detection, the presence of haemorrhage of the pulmonary artery deserves to be reported as a new observation in the context of the multiple investigations having as main subject the BTV placental crossing in cattle. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Constitutively active form of natriuretic peptide receptor 2 ameliorates experimental pulmonary arterial hypertension

    Directory of Open Access Journals (Sweden)

    Nobutoshi Nawa

    2016-01-01

    Full Text Available We recently found a constitutively active mutant of natriuretic peptide receptor 2 (caNPR2; V883M, which synthesizes larger amounts of cyclic guanosine monophosphate (cGMP intracellularly without any ligand stimulation than existing drugs. The aim of this study was to investigate the therapeutic effects of gene transduction using caNPR2 for pulmonary arterial hypertension (PAH. In vitro gene transduction into human pulmonary arterial smooth muscle cells using Sendai virus (SeV vectors carrying caNPR2 induced 10,000-fold increases in the synthesis of cGMP without ligand stimulation, and the proliferation of caNPR2-expressing cells was significantly attenuated. The PAH model rats generated by hypoxia and the administration of SU5416 were then treated with SeV vectors through a direct injection into the left pulmonary artery. Right ventricular systolic pressure was significantly decreased 2 weeks after the treatment, while systemic blood pressure remained unchanged. Histological analyses revealed that the medial wall thickness and occlusion rate of pulmonary arterioles were significantly improved in caNPR2-treated lungs. Neither the systemic integration of virus vectors nor side effects were observed. The massive stimulation of cGMP synthesis by gene therapy with caNPR2 was safe and effective in a PAH rat model and, thus, has potential as a novel therapy for patients with severe progressive PAH.

  14. On-chip laser Doppler vibrometer for arterial pulse wave velocity measurement.

    Science.gov (United States)

    Li, Yanlu; Segers, Patrick; Dirckx, Joris; Baets, Roel

    2013-07-01

    Pulse wave velocity (PWV) is an important marker for cardiovascular risk. The Laser Doppler vibrometry has been suggested as a potential technique to measure the local carotid PWV by measuring the transit time of the pulse wave between two locations along the common carotid artery (CCA) from skin surface vibrations. However, the present LDV setups are still bulky and difficult to handle. We present in this paper a more compact LDV system integrated on a CMOS-compatible silicon-on-insulator substrate. In this system, a chip with two homodyne LDVs is utilized to simultaneously measure the pulse wave at two different locations along the CCA. Measurement results show that the dual-LDV chip can successfully conduct the PWV measurement.

  15. Experimental measurement of effective atomic number of composite ...

    Indian Academy of Sciences (India)

    In this paper, we report a new method to determine the effective atomic number, eff, of composite materials for Compton effect in the γ -ray region 280–1115 keV based on the theoretically obtained Klein–Nishina scattering cross-sections in the angular range 50°–100° as well as a method to experimentally measure ...

  16. Intravenous acetylsalicylic acid, magnesium and their combination in experimental arterial thrombosis in rats.

    Science.gov (United States)

    Fuglsang, J; Ravn, H B; Toft, G E; Thorwest, M; Husted, S E; Hjortdal, V E

    1999-09-01

    Intravenous acetylsalicylic acid (ASA) and magnesium (Mg) both possess antiplatelet properties and are thus potential inhibitors of the formation of arterial thrombi. Their effect on the dynamic aspects of arterial thrombus formation was investigated following intravenous administration of both substances alone and in combination. A blinded, placebo-controlled, in-vivo study was performed in 71 rats. Thrombus formation was induced by a standardized arteriotomy in the right femoral artery with inversion of the vessel wall during subsequent closure. Thrombus formation was recorded on video tapes and analysed off-line for 30 min. Animals were randomly assigned to one of four groups: 20 mg bolus of ASA followed by 0.3 mmol/h Mg (ASA/Mg group); NaCl followed by 0.3 mmol/h Mg (Mg group); 20 mg bolus of ASA followed by NaCl (ASA group); or NaCl throughout the experiment (control group). In the ASA-treated groups, serum levels of thromboxane B2 were reduced significantly, and the Mg-treated groups reached a serum level of Mg just above 2.0 mmol/l. No significant differences were observed in initial or maximum thrombus area or in mean thrombus area during the study period. In the ASA/Mg group, a trend towards reduced thrombus formation was observed (P = 0.06). In the same group, seven of 22 animals developed an occlusive thrombus (P < 0.01), an unexpected adverse event possibly related to the combined administration of ASA and Mg.

  17. US Features of Experimentally-induced Transient Ischemia and Infarct of Renal Segmental Artery of Rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byung Kwan [Seoul National University College of Medicine, Seoul (Korea, Republic of); Kim, Seung Hyup; Moon, Min Hoan [Samsung Medical Center, Sungkyunkwan University College of Medicine, Seoul (Korea, Republic of)

    2004-09-15

    The goal of this study was to analyze and compare the changes in renal parenchymal morphology and cortical perfusion following transient arterial ischemia and infarct in rabbits using ultrasonography (US). Six rabbits were divided into the ischemia (n=3) and infarct groups (n=3). In the ischemia group, a lower polar branch of the left renal artery was surgically ligated for a duration of 60 minutes and then released, in order to induce transient renal ischemia and reperfusion. In the infarct group, a lower polar branch of the left renal artery was permanently ligated without release, in order to induce renal infarction. Gray-scale and contrast-enhanced color/power Doppler US were performed in the two groups at specific times, namely before ligation, immediately after release or ligation (for the ischemia and infarct groups, respectively?), and on the 1st, 3rd, 7th, 14th and 28th postoperative days. The left kidneys of all rabbits were harvested after the last US, for the purpose of evaluating the pathologic correlations. In the US images, swelling, hypo- or hyperechoic areas of the involved parenchyma, tissue loss and perfusion defects were more predominant in the infarct group than in the ischemia group. In successive images, hyperechoic renal parenchyma with no reperfusion changed into renal infarct, while that with reperfusion became normal tissue. In the pathologic analysis, the specimens obtained from the ischemia group revealed mild parenchymal infarct with interstitial fibrosis, whereas those from the infarct group revealed extensive tissue loss and scarring in the involved area of the lower pole. Gray-scale and contrast-enhanced color/power Doppler US can demonstrate the morphological and hemodynamic changes in cases of renal ischemia and infarct

  18. Placement of Endovascular Stent across the Branching Arteries: Long-term Serial Evaluation of Stent-tissue Responses Overlying the Arterial Orifices in an Experimental Study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Il; Chung, Jin Wook, E-mail: chungjw@snu.ac.kr [Seoul National University College of Medicine, Department of Radiology (Korea, Republic of); Kim, Hyun Beom [National Cancer Center of Korea, Department of Radiology and Center for Liver Cancer, Research Institute and Hospital (Korea, Republic of); Park, Jae Hyung [Seoul National University College of Medicine, Department of Radiology (Korea, Republic of); Seo, Jeong Wook [Seoul National University College of Medicine, Department of Pathology (Korea, Republic of); Kim, Hyo-Cheol; Jae, Hwan Jun; Lee, Whal [Seoul National University College of Medicine, Department of Radiology (Korea, Republic of)

    2012-10-15

    PurposeThis study was designed to investigate the effects of stenting across the branching arteries on the patency and stent-tissue responses over the branching arterial orifices. Methods: Thirteen dogs were observed after placing aortic stents across the celiac arteries (CA), superior mesenteric arteries (SMA), and renal arteries (RA). The animals were grouped according to stent types: large-cell group (n = 6) and small-cell group (n = 7). Angiography was performed to evaluate the branching artery patency at 2, 6, and 12 months after stent insertion, and the stent-tissue responses covering the orifices were evaluated on histopathologic examination. Results: All branching arteries were patent on follow-up angiography; however, three patterns of stent-tissue responses over the orifices were observed: neointimal layering, bridging septa, and papillary hyperplasia. Although neointimal layering and bridging septa were evenly observed, severe papillary hyperplasia was more frequent at SMA and CA than RA. Four RA showed less than 50% ostial patency, and localized infarct was observed in six kidneys (24%). The ostial patency tended to decrease with small-cell stent during the follow-up period. Conclusions: Various stent-tissue responses over the branching artery orifices are induced by the aortic stent covering the branching arteries and may not be easily detected by conventional angiography. Subclinical renal infarct also may occur despite patent renal angiography.

  19. Location of the internal carotid artery and ophthalmic artery segments for non-invasive intracranial pressure measurement by multi-depth TCD.

    Science.gov (United States)

    Hamarat, Yasin; Deimantavicius, Mantas; Kalvaitis, Evaldas; Siaudvytyte, Lina; Januleviciene, Ingrida; Zakelis, Rolandas; Bartusis, Laimonas

    2017-12-01

    The aim of the present study was to locate the ophthalmic artery by using the edge of the internal carotid artery (ICA) as the reference depth to perform a reliable non-invasive intracranial pressure measurement via a multi-depth transcranial Doppler device and to then determine the positions and angles of an ultrasonic transducer (UT) on the closed eyelid in the case of located segments. High tension glaucoma (HTG) patients and healthy volunteers (HVs) undergoing non-invasive intracranial pressure measurement were selected for this prospective study. The depth of the edge of the ICA was identified, followed by a selection of the depths of the IOA and EOA segments. The positions and angles of the UT on the closed eyelid were measured. The mean depth of the identified ICA edge for HTG patients was 64.3 mm and was 63.0 mm for HVs (p = 0.21). The mean depth of the selected IOA segment for HTG patients was 59.2 mm and 59.3 mm for HVs (p = 0.91). The mean depth of the selected EOA segment for HTG patients was 48.5 mm and 49.8 mm for HVs (p = 0.14). The difference in the located depths of the segments between groups was not statistically significant. The results showed a significant difference in the measured UT angles in the case of the identified edge of the ICA and selected ophthalmic artery segments (p = 0.0002). We demonstrated that locating the IOA and EOA segments can be achieved using the edge of the ICA as a reference point. OA: ophthalmic artery; IOA: intracranial segments of the ophthalmic artery; EOA: extracranial segments of the ophthalmic artery; ICA: internal carotid artery; UT: ultrasonic transducer; HTG: high tension glaucoma; SD: standard deviation; ICP: intracranial pressure; TCD: transcranial Doppler.

  20. Measurements of cardiac output obtained with transesophageal echocardiography and pulmonary artery thermodilution are not interchangeable

    DEFF Research Database (Denmark)

    Møller-Sørensen, H; Graeser, K; Hansen, K L

    2014-01-01

    was placed in the following successive positions: supine, head-down tilt, head-up tilt, supine, supine with phenylephrine administration, pace heart rate 80 beats per minute (bpm), pace heart rate 110 bpm. TEE CO and PAC CO were measured simultaneously. The agreement was analysed by Bland-Altman plots......BACKGROUND: Echocardiography is increasingly becoming an integrated tool for circulatory evaluation in the intensive care unit and the operating room. Therefore, it is imperative to know the reproducibility of measurements obtained by echocardiography. In this study, a comparison of cardiac output...... (CO) measurements obtained with transesophageal echocardiography (TEE) and pulmonary artery catheter (PAC) thermodilution (TD) was carried out to test the precision, accuracy and trending ability of CO measurements obtained with TEE. METHODS: Twenty-five patients completed the study. Each patient...

  1. Experimentally validated microstructural 3D constitutive model of coronary arterial media.

    Science.gov (United States)

    Hollander, Yaniv; Durban, David; Lu, Xiao; Kassab, Ghassan S; Lanir, Yoram

    2011-03-01

    Accurate modeling of arterial response to physiological or pathological loads may shed light on the processes leading to initiation and progression of a number of vascular diseases and may serve as a tool for prediction and diagnosis. In this study, a microstructure based hyperelastic constitutive model is developed for passive media of porcine coronary arteries. The most general model contains 12 independent parameters representing the three-dimensional inner fibrous structure of the media and includes the effects of residual stresses and osmotic swelling. Parameter estimation and model validation were based on mechanical data of porcine left anterior descending (LAD) media under radial inflation, axial extension, and twist tests. The results show that a reduced four parameter model is sufficient to reliably predict the passive mechanical properties. These parameters represent the stiffness and the helical orientation of each lamellae fiber and the stiffness of the interlamellar struts interconnecting these lamellae. Other structural features, such as orientational distribution of helical fibers and anisotropy of the interlamellar network, as well as possible transmural distribution of structural features, were found to have little effect on the global media mechanical response. It is shown that the model provides good predictions of the LAD media twist response based on parameters estimated from only biaxial tests of inflation and extension. In addition, good predictive capabilities are demonstrated for the model behavior at high axial stretch ratio based on data of law stretches.

  2. Comparison of arterial blood pressure measurements and hypertension scores obtained by use of three indirect measurement devices in hospitalized dogs.

    Science.gov (United States)

    Wernick, Morena B; Höpfner, Robert M; Francey, Thierry; Howard, Judith

    2012-04-15

    To evaluate the agreement of blood pressure measurements and hypertension scores obtained by use of 3 indirect arterial blood pressure measurement devices in hospitalized dogs. Design-Diagnostic test evaluation. 29 client-owned dogs. 5 to 7 consecutive blood pressure readings were obtained from each dog on each of 3 occasions with a Doppler ultrasonic flow detector, a standard oscillometric device (STO), and a high-definition oscillometric device (HDO). When the individual sets of 5 to 7 readings were evaluated, the coefficient of variation for systolic arterial blood pressure (SAP) exceeded 20% for 0% (Doppler), 11 % (STO), and 28% (HDO) of the sets of readings. After readings that exceeded a 20% coefficient of variation were discarded, repeatability was within 25 (Doppler), 37 (STO), and 39 (HDO) mm Hg for SAP. Correlation of mean values among the devices was between 0.47 and 0.63. Compared with Doppler readings, STO underestimated and HDO overestimated SAP. Limits of agreement between mean readings of any 2 devices were wide. With the hypertension scale used to score SAP, the intraclass correlation of scores was 0.48. Linear-weighted inter-rater reliability between scores was 0.40 (Doppler vs STO), 0.38 (Doppler vs HDO), and 0.29 (STO vs HDO). Results of this study suggested that no meaningful clinical comparison can be made between blood pressure readings obtained from the same dog with different indirect blood pressure measurement devices.

  3. Noninvasive Doppler tissue measurement of pulmonary artery compliance in children with pulmonary hypertension.

    Science.gov (United States)

    Dyer, Karrie; Lanning, Craig; Das, Bibhuti; Lee, Po-Feng; Ivy, D Dunbar; Valdes-Cruz, Lilliam; Shandas, Robin

    2006-04-01

    We have shown previously that input impedance of the pulmonary vasculature provides a comprehensive characterization of right ventricular afterload by including compliance. However, impedance-based compliance assessment requires invasive measurements. Here, we develop and validate a noninvasive method to measure pulmonary artery (PA) compliance using ultrasound color M-mode (CMM) Doppler tissue imaging (DTI). Dynamic compliance (C(dyn)) of the PA was obtained from CMM DTI and continuous wave Doppler measurement of the tricuspid regurgitant velocity. C(dyn) was calculated as: [(D(s) - D(d))/(D(d) x P(s))] x 10(4); where D(s) = systolic diameter, D(d) = diastolic diameter, and P(s) = systolic pressure. The method was validated both in vitro and in 13 patients in the catheterization laboratory, and then tested on 27 pediatric patients with pulmonary hypertension, with comparison with 10 age-matched control subjects. C(dyn) was also measured in an additional 13 patients undergoing reactivity studies. Instantaneous diameter measured using CMM DTI agreed well with intravascular ultrasound measurements in the in vitro models. Clinically, C(dyn) calculated by CMM DTI agreed with C(dyn) calculated using invasive techniques (23.4 +/- 16.8 vs 29.1 +/- 20.6%/100 mm Hg; P = not significant). Patients with pulmonary hypertension had significantly lower peak wall velocity values and lower C(dyn) values than control subjects (P < .01). C(dyn) values followed an exponentially decaying relationship with PA pressure, indicating the nonlinear stress-strain behavior of these arteries. Reactivity in C(dyn) agreed with reactivity measured using impedance techniques. The C(dyn) method provides a noninvasive means of assessing PA compliance and should be useful as an additional measure of vascular reactivity subsequent to pulmonary vascular resistance in patients with pulmonary hypertension.

  4. Experimental Method for Measuring Dust Load on Surfaces in Rooms

    DEFF Research Database (Denmark)

    Lengweiler, Philip; Nielsen, Peter V.; Moser, Alfred

    A new experimental setup to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust-related problems in rooms, there is a n......A new experimental setup to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust-related problems in rooms......, there is a need for better understanding of the mechanism of dust deposition and resuspension. With the presented experimental setup, the dust load on surfaces in a channel can be measured as a function of the environmental and surface conditions and the type of particles under controlled laboratory conditions....

  5. Experimental measurement of structural power flow on an aircraft fuselage

    Science.gov (United States)

    Cuschieri, J. M.

    1991-01-01

    An experimental technique is used to measure structural intensity through an aircraft fuselage with an excitation load applied near one of the wing attachment locations. The fuselage is a relatively large structure, requiring a large number of measurement locations to analyze the whole of the structure. For the measurement of structural intensity, multiple point measurements are necessary at every location of interest. A tradeoff is therefore required between the number of measurement transducers, the mounting of these transducers, and the accuracy of the measurements. Using four transducers mounted on a bakelite platform, structural intensity vectors are measured at locations distributed throughout the fuselage. To minimize the errors associated with using the four transducer technique, the measurement locations are selected to be away from bulkheads and stiffeners. Furthermore, to eliminate phase errors between the four transducer measurements, two sets of data are collected for each position, with the orientation of the platform with the four transducers rotated by 180 degrees and an average taken between the two sets of data. The results of these measurements together with a discussion of the suitability of the approach for measuring structural intensity on a real structure are presented.

  6. End-tidal and arterial carbon dioxide measurements correlate across all levels of physiologic dead space.

    Science.gov (United States)

    McSwain, S David; Hamel, Donna S; Smith, P Brian; Gentile, Michael A; Srinivasan, Saumini; Meliones, Jon N; Cheifetz, Ira M

    2010-03-01

    End-tidal carbon dioxide (P(ETCO(2))) is a surrogate, noninvasive measurement of arterial carbon dioxide (P(aCO(2))), but the clinical applicability of P(ETCO(2)) in the intensive care unit remains unclear. Available research on the relationship between P(ETCO(2)) and P(aCO(2)) has not taken a detailed assessment of physiologic dead space into consideration. We hypothesized that P(ETCO(2)) would reliably predict P(aCO(2)) across all levels of physiologic dead space, provided that the expected P(ETCO(2))-P(aCO(2)) difference is considered. Fifty-six mechanically ventilated pediatric patients (0-17 y old, mean weight 19.5 +/- 24.5 kg) were monitored with volumetric capnography. For every arterial blood gas measurement during routine care, we measured P(ETCO(2)) and calculated the ratio of dead space to tidal volume (V(D)/V(T)). We assessed the P(ETCO(2))-P(aCO(2)) relationship with Pearson's correlation coefficient, in 4 V(D)/V(T) ranges. V(D)/V(T) was measurements (25%), 0.41-0.55 for 160 measurements (32%), 0.56-0.70 for 154 measurements (31%), and >0.7 for 54 measurements (11%). The correlation coefficients between P(ETCO(2)) and P(aCO(2)) were 0.95 (mean difference 0.3 +/- 2.1 mm Hg) for V(D)/V(T) 0.7. There were strong correlations between P(ETCO(2)) and P(aCO(2)) in all the V(D)/V(T) ranges. The P(ETCO(2))-P(aCO(2)) difference increased predictably with increasing V(D)/V(T).

  7. Measurement of peripheral blood flow in patients with peripheral artery disease: Methods and considerations.

    Science.gov (United States)

    Salisbury, Dereck L; Brown, Rebecca Jl; Bronas, Ulf G; Kirk, Laura N; Treat-Jacobson, Diane

    2018-02-01

    Peripheral artery disease (PAD) is a manifestation of generalized atherosclerosis which results in hemodynamic compromise of oxygen and substrate delivery to the lower extremity skeletal muscles. Hemodynamic assessments are vital in PAD diagnosis and in the evaluation of strategies aimed at treating claudication (i.e. exercise training, revascularization, and pharmacological agents). Venous occlusion plethysmography (VOP) is a century-old, non-invasive technique used to quantify limb blood flow and has been used to evaluate hemodynamic compromise in patients with PAD. However, the literature suggests a wide array of methodological variability in the measurement and analysis of limb blood flow using VOP. In this manuscript, we overview the clinical application of VOP measurement, and secondly we review the methodological variation that occurs during the measurement and analysis of VOP in healthy individuals and in patients with claudication.

  8. Techniques of cardiac output measurement during liver transplantation: arterial pulse wave versus thermodilution

    DEFF Research Database (Denmark)

    Nissen, P.; Lieshout, J.J. van; Novovic, S.

    2009-01-01

    variables were measured in 39 adult patients (13 females) every 10th minute during liver transplant surgery. Paired measurements were compared during the 4 phases of surgery-dissection, anhepatic phase, early reperfusion (the first 15 minutes after reperfusion), and late reperfusion (15-60 minutes after......In this study, we compared continuous cardiac output (CO) obtained from the femoral arterial pressure by simulation of an aortic input impedance model [model-simulated cardiac output (MCO)] to thermodilution cardiac output (TDCO) determined by bolus injection during liver transplantation. Both......, and the mutual correlation coefficient was 0.812 (P surgery, MCO reflects TDCO throughout the operation. Thus, for CO, this less invasive method appears to provide a reliable uninterrupted measurement during orthotopic liver transplantation...

  9. Vascularização temporária de membros isquêmicos por meio de shunt arteriomedular: trabalho experimental Temporary vascularization on ischemic limbs through arterial-medullar shunt: an experimental work

    Directory of Open Access Journals (Sweden)

    Ronaldo André Poerschke

    2012-03-01

    Full Text Available CONTEXTO: Os autores idealizaram um shunt temporário entre a artéria femoral e o canal medular de ossos longos para manter a viabilidade dos membros agudamente isquêmicos, enquanto não é possível estabelecer um tratamento definitivo. OBJETIVO: Avaliar a perviedade de shunts temporários arteriomedulares e a perfusão dos membros, durante duas horas em cães de experimentação, que tiveram a artéria femoral ligada. MÉTODOS: Alocaram-se aleatoriamente dois grupos, com três cães no Grupo Controle e seis no Grupo Intervenção. Os controles tiveram a artéria femoral comum direita ligada. O Grupo Intervenção, além da ligadura da artéria, recebeu um shunt. Após duas horas, realizou-se a medida de pH dos membros isquêmicos; avaliação do fluxo arterial por meio de um sonar Doppler; avaliação da coloração do sangramento na extremidade distal do membro e foram retirados em bloco torácico os pulmões para análise anatomopatológica. RESULTADOS: A média do pH do sangue capilar das extremidades do membros no Grupo Controle foi de 6,97 (±0,39; no Grupo Intervenção o pH foi de 7,25 (±0,46, com pBACKGROUND: The authors idealized a temporary shunt between the femoral artery and the medullar canal on long bones to keep the viability of acutely ischemic limbs, while waiting for a definitive treatment. OBJECTIVE: To assess the flow on temporary shunts between the femoral artery and the marrow canal of the tibia during two hours in experimental dogs, which had the femoral artery interrupted. METHODS: Two groups with three dogs on the Control Group and six on the Intervention Group were allocated at random. The controls had the right femoral common artery interrupted. The Intervention Group received a shunt between the iliac external artery and the medullar canal of the right tibia in addition. After two hours, the measure of the pH, blood coloration, blood flow in sonar Doppler on the ischemic limbs were performed. The lungs were

  10. Comparison between oscillometric and intra-arterial blood pressure measurements in ill preterm and full-term neonates.

    Science.gov (United States)

    Lalan, Shwetal; Blowey, Douglas

    2014-01-01

    Conflicting data exist regarding the accuracy of the oscillometric method of blood pressure (BP) measurement in neonates. There is limited data regarding intra-arterial BP trends in neonates. We aimed to determine the accuracy of oscillometric BP measurements and to evaluate the BP distributions in ill neonates. A total of 1492 simultaneously obtained oscillometric and intra-arterial (umbilical arterial [UAC] or radial arterial) BP measurements were used for comparisons and 125,580 intra-arterial BP readings were used to the evaluate BP distribution. There was a statistically significant difference (P oscillometric and radial mean arterial BP (MAP) 4.8 ± 9.8 mm Hg, systolic BP 8.3 ± 11.6 mm Hg, diastolic BP 4.3 ± 9.3 mm Hg and between the oscillometric and UAC systolic BP 5.2 ± 11.9 mm Hg and diastolic BP -0.8 ± 10.4 mm Hg. The MAP increased with increases in weight (35.3 ± 4.92 mm Hg/kg), post-menstrual age (-0.29 ± 1.41 mm Hg/week) and advanced gestational age at birth (13.12 ± 0.90 mm Hg/week). Oscillometric BP measurements are not equivalent to the intra-arterial (UAC or radial arterial) BP in ill neonates. The BP increases with increase in weight, gestational age at birth, and post-menstrual age in ill neonates. Copyright © 2014 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

  11. Evaluation of MR angiography and blood flow measurement in abdominal and peripheral arterial occlusive disease

    Energy Technology Data Exchange (ETDEWEB)

    Tabuchi, Kenji [Dokkyo Univ. School of Medicine, Mibu, Tochigi (Japan)

    2000-03-01

    To assess the characteristics of blood flow measurement with MR Angiography (MRA) to evaluate the status of vascular stenoses, two or three dimensional time-of-flight MRA and velocity-encoded cine MR were performed in the 230 segments of 35 patients, with abdominal and peripheral arterial occlusive diseases. In 11 of these 35 patients digital subtraction angiography was additionally underwent, and the stenotic findings was compared with MRA. There were 17 segments in which the velocity could not be measured, because the blood flow exceeded the upper limit of peak-encoded velocity (VENC) which was set at 120 cm/sec. Therefore, it is necessary to set the upper limit of VENC at higher than 120 cm/sec. There were 11 stenotic findings in DSA and 20 stenotic findings in MRA. Pulsatility Index (PI=(max velocity-min. velocity)/average velocity) were used for evaluating the blood flow waveform, and there were significant difference between the 11 stenotic findings of DSA and the others'. In summery, MRA was considered as useful examination to assess the degree of the vascular stenoses in abdominal and peripheral arterial occlusive disease. (author)

  12. Noninvasive measurements of regional cerebral perfusion in preterm and term neonates by magnetic resonance arterial spin labeling

    DEFF Research Database (Denmark)

    Miranda Gimenez-Ricco, Maria Jo; Olofsson, K; Sidaros, Karam

    2006-01-01

    Magnetic resonance arterial spin labeling (ASL) at 3 Tesla has been investigated as a quantitative technique for measuring regional cerebral perfusion (RCP) in newborn infants. RCP values were measured in 49 healthy neonates: 32 preterm infants born before 34 wk of gestation and 17 term-born neon......Magnetic resonance arterial spin labeling (ASL) at 3 Tesla has been investigated as a quantitative technique for measuring regional cerebral perfusion (RCP) in newborn infants. RCP values were measured in 49 healthy neonates: 32 preterm infants born before 34 wk of gestation and 17 term...

  13. THE EXPERIMENTAL VALIDATION OF THE GROUNDING DEVICE RESISTANCE MEASUREMENT METHOD

    Directory of Open Access Journals (Sweden)

    I. V. Nizhevskyi

    2016-12-01

    Full Text Available Purpose. The paper considers experimental research of three-electrode units for measuring the resistance of grounding devices for different purposes. Methodology. The experimental study of the method of resistance measurement of grounding devices for any design in any soil structure using the method of physical modeling is presented. Results. By results of model operation the set of equations of the sixth order is solved. It allowed to determine the own and mutual impedance in the three-electrode unit with high accuracy without searching the point of zero potential. Features of measuring and defining the own and relative resistances of various combinations of electrodes for three-electrode measuring unit are considered. Originality. The necessity of finding a zero potential point is excluded. Practical value. The proposed method provides the smallest possible spacing of potential electrodes outside the grounding devices. This reduces the wiring length measurement circuit in several times, increases the ratio «signal – noise», removes the restrictions on building of the territory outside the test grounding device.

  14. Experimental temperature measurements for the energy amplifier test

    Energy Technology Data Exchange (ETDEWEB)

    Calero, J. [Centro de Estudios y Experimentacion de Obras Publicas (CEDEX), Madrid (Spain); Cennini, P. [European Laboratory for Particle Physics, CH-1211 Geneva 23 (Switzerland); Gallego, E. [Universidad Politecnica de Madrid (UPM), E-28040 Madrid (Spain); Galvez, J. [European Laboratory for Particle Physics, CH-1211 Geneva 23 (Switzerland)]|[Universidad Autonoma de Madrid (UAM), E-28049 Madrid (Spain); Garcia Tabares, L. [Centro de Estudios y Experimentacion de Obras Publicas (CEDEX), Madrid (Spain); Gonzalez, E. [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), E-28040 Madrid (Spain); Jaren, J. [Universidad Autonoma de Madrid (UAM), E-28049 Madrid (Spain); Lopez, C. [Universidad Autonoma de Madrid (UAM), E-28049 Madrid (Spain); Lorente, A. [Universidad Politecnica de Madrid (UPM), E-28040 Madrid (Spain); Martinez Val, J.M. [Universidad Politecnica de Madrid (UPM), E-28040 Madrid (Spain); Oropesa, J. [European Laboratory for Particle Physics, CH-1211 Geneva 23 (Switzerland); Rubbia, C. [European Laboratory for Particle Physics, CH-1211 Geneva 23 (Switzerland); Rubio, J.A. [European Laboratory for Particle Physics, CH-1211 Geneva 23 (Switzerland)]|[Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), E-28040 Madrid (Spain); Saldana, F. [European Laboratory for Particle Physics, CH-1211 Geneva 23 (Switzerland); Tamarit, J. [Centro de Estudios y Experimentacion de Obras Publicas (CEDEX), Madrid (Spain); Vieira, S. [Universidad Autonoma de Madrid (UAM), E-28049 Madrid (Spain)

    1996-06-21

    A uranium thermometer has been designed and built in order to make local power measurements in the first energy amplifier test (FEAT). Due to the experimental conditions power measurements of tens to hundreds of nW were required, implying a sensitivity in the temperature change measurements of the order of 1 mK. A uranium thermometer accurate enough to match that sensitivity has been built. The thermometer is able to determine the absolute energetic gain obtained in a tiny subcritical uranium assembly exposed to a proton beam of kinetic energies between 600 MeV and 2.75 GeV. In addition, the thermometer measurements have provided information about the spatial power distribution and the shape of the neutron spallation cascade. (orig.).

  15. Endothelial dysfunction in obstructive sleep apnea measured by peripheral arterial tone response in the finger to reactive hyperemia.

    Science.gov (United States)

    Itzhaki, Sarah; Lavie, Lena; Pillar, Giora; Tal, Galit; Lavie, Peretz

    2005-05-01

    The aim of this study was to investigate endothelial functioning in sleep apnea patients using a novel plethysmographic device that monitors peripheral arterial tone response in the finger to reactive hyperemia induced by forearm ischemia. Forty-six sleep apnea patients, 74.0% men, mean age 46.8 +/- 9.3 years, and 17 control subjects without sleep apnea, 64.7% men, mean age 47.1 +/- 6.7 years. Eight-bed Technion Sleep Medicine Center in Haifa, Israel. Endothelial functioning assessed by the reactive hyperemia peripheral arterial tone index was measured twice, before sleep and after waking from sleep monitored by polysomnography in the laboratory. The reactive hyperemia peripheral arterial tone index was calculated as the average amplitude of the peripheral arterial tone signal after the cuff deflation divided by the average amplitude before the cuff inflation. Morning index of endothelial functioning was significantly lower in patients with moderate to severe sleep apnea (apnea-hypopnea index > or = 30) than in patients with mild sleep apnea (30 disease had significantly lower morning and evening indexes of endothelial functioning than patients without such a history. Multivariate analysis revealed that apnea-hypopnea index and sleep efficiency were significant predictors of the morning index. Measurements of the response of the peripheral arterial tone in the finger to reactive hyperemia can be used as a substitute for the brachial artery ultrasound technique to measure endothelial functioning in patients with sleep apnea.

  16. Radial artery pulse pressure variation correlates with brachial artery peak velocity variation in ventilated subjects when measured by internal medicine residents using hand-carried ultrasound devices.

    Science.gov (United States)

    Brennan, J Matthew; Blair, John E A; Hampole, Chetan; Goonewardena, Sascha; Vasaiwala, Samip; Shah, Dipak; Spencer, Kirk T; Schmidt, Gregory A

    2007-05-01

    Rapid prediction of the effect of volume expansion is crucial in unstable patients receiving mechanical ventilation. Both radial artery pulse pressure variation (DeltaPP) and change of aortic blood flow peak velocity are accurate predictors but may be impractical point-of-care tools. We sought to determine whether respiratory changes in the brachial artery blood flow velocity (DeltaVpeak-BA) as measured by internal medicine residents using a hand-carried ultrasound (HCU) device could provide an accurate corollary to DeltaPP in patients receiving mechanical ventilation. Thirty patients passively receiving volume-control ventilation with preexisting radial artery catheters were enrolled. The brachial artery Doppler signal was recorded and analyzed by blinded internal medicine residents using a HCU device. Simultaneous radial artery pulse wave and central venous pressure recordings (when available) were analyzed by a blinded critical care physician. A Doppler signal was obtained in all 30 subjects. The DeltaVpeak-BA correlated well with DeltaPP (r = 0.84) with excellent agreement (weighted kappa, 0.82) and limited intraobserver variability (2.8 +/- 2.8%) [mean +/- SD]. A DeltaVpeak-BA cutoff of 16% was highly predictive of DeltaPP > or = 13% (sensitivity, 91%; specificity, 95%). A poor correlation existed between the CVP and both DeltaVpeak-BA (r = - 0.21) and DeltaPP (r = - 0.16). The HCU Doppler assessment of the DeltaVpeak-BA as performed by internal medicine residents is a rapid, noninvasive bedside correlate to DeltaPP, and a DeltaVpeak-BA cutoff of 16% may prove useful as a point-of-care tool for the prediction of volume responsiveness in patients receiving mechanical ventilation.

  17. Quantitative Measurements of Competitive Flow in Left Internal Mammary Artery Bypass Grafts

    NARCIS (Netherlands)

    Spoor, Pien; Halfwerk, F.R.; Hagmeijer, Rob; Grandjean, J.G.

    2017-01-01

    OBJECTIVE: A low flow rate with diminished wall shear stress in arteries can cause intima hyperplasia and diameter reduction. In coronary artery bypass grafting (CABG) a low flow rate through the graft can cause graft failure (i.e. the string sign effect and occlusion). Arterial grafts bypassing an

  18. Simulated characterization of atherosclerotic lesions in the coronary arteries by measurement of bioimpedance.

    Science.gov (United States)

    Stiles, David K; Oakley, Barbara

    2003-07-01

    FEM software was used to determine the feasibility of characterizing various types of atherosclerotic lesions in vivo. This was accomplished by simulating two electrodes as being attached to an angioplasty balloon in the coronary artery. The electrodes on the "balloon" touched and measured the simulated complex impedance of type III, IV, and Va and Vb lesions, as defined by the American Heart Association (AHA). Additionally, the effect of changes in morphology on the complex impedance was determined for type Va and Vb lesions. The simulations showed that the layer closest to the electrodes had the most significant effect on the measured complex impedance. As a consequence of these simulations, it appears plausible that electrodes could be placed in vivo to determine the characteristics and type of a given atherosclerotic lesion.

  19. Increased oxidative stress and severe arterial remodeling induced by permanent high-flow challenge in experimental pulmonary hypertension

    Directory of Open Access Journals (Sweden)

    Fadel Elie

    2011-09-01

    Full Text Available Abstract Background Involvement of inflammation in pulmonary hypertension (PH has previously been demonstrated and recently, immune-modulating dendritic cells (DCs infiltrating arterial lesions in patients suffering from idiopathic pulmonary arterial hypertension (IPAH and in experimental monocrotaline-induced PH have been reported. Occurrence of perivascular inflammatory cells could be linked to local increase of oxidative stress (OS, as it has been shown for systemic atherosclerosis. The impact of OS on vascular remodeling in PH is still to be determined. We hypothesized, that augmented blood-flow could increase OS and might thereby contribute to DC/inflammatory cell-recruitment and smooth-muscle-cell-proliferation. Methods We applied a monocrotaline-induced PH-model and combined it with permanent flow-challenge. Thirty Sprague-Dawley rats were assigned to following groups: control, monocrotaline-exposure (MCT, monocrotaline-exposure/pneumonectomy (MCT/PE. Results Hemodynamic exploration demonstrated most severe effects in MCT/PE, corresponding in histology to exuberant medial and adventitial remodeling of pulmonary muscular arteries, and intimal remodeling of smaller arterioles; lung-tissue PCR evidenced increased expression of DCs-specific fascin, CD68, proinflammatory cytokines (IL-6, RANTES, fractalkine in MCT/PE and to a lesser extent in MCT. Major OS enzyme NOX-4 was maximal in MCT/PE. Antioxidative stress enzymes Mn-SOD and glutathion-peroxidase-1 were significantly elevated, while HO-1 showed maximal expression in MCT with significant decrease in MCT/PE. Catalase was decreased in MCT and MCT/PE. Expression of NOX-4, but also of MN-SOD in MCT/PE was mainly attributed to a highly increased number of interstitial and perivascular CXCR4/SDF1 pathway-recruited mast-cells. Stress markers malonedialdehyde and nitrotyrosine were produced in endothelial cells, medial smooth muscle and perivascular leucocytes of hypertensive vasculature

  20. Increased oxidative stress and severe arterial remodeling induced by permanent high-flow challenge in experimental pulmonary hypertension.

    Science.gov (United States)

    Dorfmüller, Peter; Chaumais, Marie-Camille; Giannakouli, Maria; Durand-Gasselin, Ingrid; Raymond, Nicolas; Fadel, Elie; Mercier, Olaf; Charlotte, Frédéric; Montani, David; Simonneau, Gérald; Humbert, Marc; Perros, Frédéric

    2011-09-09

    Involvement of inflammation in pulmonary hypertension (PH) has previously been demonstrated and recently, immune-modulating dendritic cells (DCs) infiltrating arterial lesions in patients suffering from idiopathic pulmonary arterial hypertension (IPAH) and in experimental monocrotaline-induced PH have been reported. Occurrence of perivascular inflammatory cells could be linked to local increase of oxidative stress (OS), as it has been shown for systemic atherosclerosis. The impact of OS on vascular remodeling in PH is still to be determined. We hypothesized, that augmented blood-flow could increase OS and might thereby contribute to DC/inflammatory cell-recruitment and smooth-muscle-cell-proliferation. We applied a monocrotaline-induced PH-model and combined it with permanent flow-challenge. Thirty Sprague-Dawley rats were assigned to following groups: control, monocrotaline-exposure (MCT), monocrotaline-exposure/pneumonectomy (MCT/PE). Hemodynamic exploration demonstrated most severe effects in MCT/PE, corresponding in histology to exuberant medial and adventitial remodeling of pulmonary muscular arteries, and intimal remodeling of smaller arterioles; lung-tissue PCR evidenced increased expression of DCs-specific fascin, CD68, proinflammatory cytokines (IL-6, RANTES, fractalkine) in MCT/PE and to a lesser extent in MCT. Major OS enzyme NOX-4 was maximal in MCT/PE. Antioxidative stress enzymes Mn-SOD and glutathion-peroxidase-1 were significantly elevated, while HO-1 showed maximal expression in MCT with significant decrease in MCT/PE. Catalase was decreased in MCT and MCT/PE. Expression of NOX-4, but also of MN-SOD in MCT/PE was mainly attributed to a highly increased number of interstitial and perivascular CXCR4/SDF1 pathway-recruited mast-cells. Stress markers malonedialdehyde and nitrotyrosine were produced in endothelial cells, medial smooth muscle and perivascular leucocytes of hypertensive vasculature. Immunolabeling for OX62, CD68 and actin revealed

  1. New principle for measuring arterial blood oxygenation, enabling motion-robust remote monitoring.

    Science.gov (United States)

    van Gastel, Mark; Stuijk, Sander; de Haan, Gerard

    2016-12-07

    Finger-oximeters are ubiquitously used for patient monitoring in hospitals worldwide. Recently, remote measurement of arterial blood oxygenation (SpO2) with a camera has been demonstrated. Both contact and remote measurements, however, require the subject to remain static for accurate SpO2 values. This is due to the use of the common ratio-of-ratios measurement principle that measures the relative pulsatility at different wavelengths. Since the amplitudes are small, they are easily corrupted by motion-induced variations. We introduce a new principle that allows accurate remote measurements even during significant subject motion. We demonstrate the main advantage of the principle, i.e. that the optimal signature remains the same even when the SNR of the PPG signal drops significantly due to motion or limited measurement area. The evaluation uses recordings with breath-holding events, which induce hypoxemia in healthy moving subjects. The events lead to clinically relevant SpO2 levels in the range 80-100%. The new principle is shown to greatly outperform current remote ratio-of-ratios based methods. The mean-absolute SpO2-error (MAE) is about 2 percentage-points during head movements, where the benchmark method shows a MAE of 24 percentage-points. Consequently, we claim ours to be the first method to reliably measure SpO2 remotely during significant subject motion.

  2. Experimental measurements of the cavitating flow after horizontal water entry

    Science.gov (United States)

    Tat Nguyen, Thang; Hai, Duong Ngoc; Quang Thai, Nguyen; Phuong, Truong Thi

    2017-10-01

    Water-entry cavitating flow is of considerable importance in underwater high-speed applications. That is because of the drag-reduction effect that concerns the presence of a cavity around moving objects. Though the study of the flow has long been carried out, little data are documented in literature so far. Besides, currently, in the case of unsteady flow, experimental measurements of some flow parameters such as the cavity pressure still encounter difficulties. Hence continuing research efforts are of important significance. The objective of this study is to investigate experimentally the unsteady cavitating flow after the horizontal water entry of projectiles. An experimental apparatus has been developed. Qualitative and quantitative optical visualizations of the flow have been carried out by using high-speed videography. Digital image processing has been applied to analyzing the recorded flow images. Based on the known correlations between the ellipsoidal super-cavity’s size and the corresponding cavitation number, the cavity pressure has been measured by utilizing the data of image processing. A comparison between the partial- and super-cavitating flow regimes is reported. The received results can be useful for the design of high-speed underwater projectiles.

  3. Variabilidad en las medidas de tensión arterial realizada por estudiantes de 5.º y 6.º de medicina Variability of arterial pressure measurements performed by advanced medical students

    Directory of Open Access Journals (Sweden)

    C. Caramelo

    2008-06-01

    Full Text Available Introducción. No se ha definido objetivamente si los estudiantes de medicina avanzados dominan destrezas básicas, como la medida de tensión arterial. Sujetos y métodos. Se determinó la variabilidad de medida de tensión arterial por estudiantes de 5.º y 6.º cursos de medicina. Resultados. Se encontraron coeficientes de variación significativamente más elevados en la tensión arterial diastólica derecha y frecuencia cardíaca, y grupos e individuos con error sistemático de medición. Conclusión. Resulta necesario un refuerzo docente en la medida de tensión arterial diastólica y su realización en los dos brazos.Introduction. No objective data are available to know whether advanced medical students are in command of basic practical skills, ie, arterial pressure measurement. Subjects and methods. Variability of arterial pressure measurements was examined in 5th- and 6th-year medical students. Results. Significantly higher variability coefficients were found in right arm diastolic arterial pressure and heart rate. A systematic measurement error was detected in some groups and individuals. Conclusion. A teaching effort will be necessary to improve arterial pressure measurement skills, with special emphasis in diastolic arterial pressure and bilateral measurements.

  4. Biosensor cell assay for measuring real-time aldosterone-induced release of histamine from mesenteric arteries

    DEFF Research Database (Denmark)

    Dalgaard, Emil G; Andersen, Kenneth; Svenningsen, Per

    2017-01-01

    AIMS: The aims were to develop a method for real-time detection of histamine release and to test if incubation with aldosterone induces histamine release from isolated, perfused mice mesenteric arteries. METHODS: Fura-2 loaded HEK-293 cells transfected with the histamine H1 receptor was used...... as a sensitive biosensor assay for histamine release from isolated mouse mesenteric arteries. Activation of the H1 receptor by histamine was measured as an increased number of intracellular Ca(2+) transient peaks using fluorescence imaging RESULTS: The developed biosensor was sensitive to histamine...... by the histamine H1 blocker pyrilamine. Mesenteric arteries from mast cell deficient SASH mice induced similar pyrilamine-sensitive Ca(2+) transient response in the biosensor cells. Mesenteric arteries from wild type and SASH mice expressed histamine decarboxylase mRNA, indicating that mast cells are not the only...

  5. Cardiac MRI in pulmonary artery hypertension: correlations between morphological and functional parameters and invasive measurements

    Energy Technology Data Exchange (ETDEWEB)

    Alunni, Jean-Philippe; Otal, Philippe; Rousseau, Herve; Chabbert, Valerie [CHU Rangueil, Department of Radiology, Toulouse (France); Degano, Bruno; Tetu, Laurent; Didier, Alain [CHU Larrey, Department of Pneumology, Toulouse (France); Arnaud, Catherine [CHU Rangueil, Department of Methods in Clinical Research, Toulouse (France); Blot-Souletie, Nathalie [CHU Rangueil, Department of Cardiology, Toulouse (France)

    2010-05-15

    To compare cardiac MRI with right heart catheterisation in patients with pulmonary hypertension (PH) and to evaluate its ability to assess PH severity. Forty patients were included. MRI included cine and phase-contrast sequences, study of ventricular function, cardiac cavity areas and ratios, position of the interventricular septum (IVS) in systole and diastole, and flow measurements. We defined four groups according to the severity of PH and three groups according to IVS position: A, normal position; B, abnormal in diastole; C, abnormal in diastole and systole. IVS position was correlated with pulmonary artery pressures and PVR (pulmonary vascular resistance). Median pulmonary artery pressures and resistance were significantly higher in patients with an abnormal septal position compared with those with a normal position. Correlations were good between the right ventricular ejection fraction and PVR, right ventricular end-systolic volume and PAP, percentage of right ventricular area change and PVR, and diastolic and systolic ventricular area ratio and PVR. These parameters were significantly associated with PH severity. Cardiac MRI can help to assess the severity of PH. (orig.)

  6. Experimental measurements and noise analysis of a cryogenic radiometer

    Energy Technology Data Exchange (ETDEWEB)

    Carr, S. M.; Woods, S. I.; Jung, T. M.; Carter, A. C.; Datla, R. U. [National Institute of Standards and Technology (NIST), 100 Bureau Drive, Gaithersburg, Maryland 20899 (United States)

    2014-07-15

    A cryogenic radiometer device, intended for use as part of an electrical-substitution radiometer, was measured at low temperature. The device consists of a receiver cavity mechanically and thermally connected to a temperature-controlled stage through a thin-walled polyimide tube which serves as a weak thermal link. With the temperature difference between the receiver and the stage measured in millikelvin and the electrical power measured in picowatts, the measured responsivity was 4700 K/mW and the measured thermal time constant was 14 s at a stage temperature of 1.885 K. Noise analysis in terms of Noise Equivalent Power (NEP) was used to quantify the various fundamental and technical noise contributions, including phonon noise and Johnson-Nyquist noise. The noise analysis clarifies the path toward a cryogenic radiometer with a noise floor limited by fundamental phonon noise, where the magnitude of the phonon NEP is 6.5 fW/√(Hz) for the measured experimental parameters.

  7. Transauricular embolization of the rabbit coronary artery for experimental myocardial infarction: comparison of a minimally invasive closed-chest model with open-chest surgery

    Directory of Open Access Journals (Sweden)

    Katsanos Konstantinos

    2012-02-01

    Full Text Available Abstract Introduction To date, most animal studies of myocardial ischemia have used open-chest models with direct surgical coronary artery ligation. We aimed to develop a novel, percutaneous, minimally-invasive, closed-chest model of experimental myocardial infarction (EMI in the New Zealand White rabbit and compare it with the standard open-chest surgical model in order to minimize local and systemic side-effects of major surgery. Methods New Zealand White rabbits were handled in conformity with the "Guide for the Care and Use of Laboratory Animals" and underwent EMI under intravenous anesthesia. Group A underwent EMI with an open-chest method involving surgical tracheostomy, a mini median sternotomy incision and left anterior descending (LAD coronary artery ligation with a plain suture, whereas Group B underwent EMI with a closed-chest method involving fluoroscopy-guided percutaneous transauricular intra-arterial access, superselective LAD catheterization and distal coronary embolization with a micro-coil. Electrocardiography (ECG, cardiac enzymes and transcatheter left ventricular end-diastolic pressure (LVEDP measurements were recorded. Surviving animals were euthanized after 4 weeks and the hearts were harvested for Hematoxylin-eosin and Masson-trichrome staining. Results In total, 38 subjects underwent EMI with a surgical (n = 17 or endovascular (n = 21 approach. ST-segment elevation (1.90 ± 0.71 mm occurred sharply after surgical LAD ligation compared to progressive ST elevation (2.01 ± 0.84 mm;p = 0.68 within 15-20 min after LAD micro-coil embolization. Increase of troponin and other cardiac enzymes, abnormal ischemic Q waves and LVEDP changes were recorded in both groups without any significant differences (p > 0.05. Infarct area was similar in both models (0.86 ± 0.35 cm in the surgical group vs. 0.92 ± 0.54 cm in the percutaneous group;p = 0.68. Conclusion The proposed model of transauricular coronary coil embolization avoids

  8. Investigation of Ultrasound-Measured Flow Velocity, Flow Rate and Wall Shear Rate in Radial and Ulnar Arteries Using Simulation.

    Science.gov (United States)

    Zhou, Xiaowei; Xia, Chunming; Stephen, Gandy; Khan, Faisel; Corner, George A; Hoskins, Peter R; Huang, Zhihong

    2017-05-01

    Parameters of blood flow measured by ultrasound in radial and ulnar arteries, such as flow velocity, flow rate and wall shear rate, are widely used in clinical practice and clinical research. Investigation of these measurements is useful for evaluating accuracy and providing knowledge of error sources. A method for simulating the spectral Doppler ultrasound measurement process was developed with computational fluid dynamics providing flow-field data. Specific scanning factors were adjusted to investigate their influence on estimation of the maximum velocity waveform, and flow rate and wall shear rate were derived using the Womersley equation. The overestimation in maximum velocity increases greatly (peak systolic from about 10% to 30%, time-averaged from about 30% to 50%) when the beam-vessel angle is changed from 30° to 70°. The Womersley equation was able to estimate flow rate in both arteries with less than 3% error, but performed better in the radial artery (2.3% overestimation) than the ulnar artery (15.4% underestimation) in estimating wall shear rate. It is concluded that measurements of flow parameters in the radial and ulnar arteries with clinical ultrasound scanners are prone to clinically significant errors. Copyright © 2017. Published by Elsevier Inc.

  9. Validity and reproducibility of arterial pulse wave velocity measurement using new device with oscillometric technique: A pilot study

    Directory of Open Access Journals (Sweden)

    Patnaik Amar

    2005-08-01

    Full Text Available Abstract Background Availability of a range of techniques and devices allow measurement of many variables related to the stiffness of large or medium sized arteries. There is good evidence that, pulse wave velocity is a relatively simple measurement and is a good indicator of changes in arterial properties. The pulse wave velocity calculated from pulse wave recording by other methods like doppler or tonometry is tedious, time-consuming and above all their reproducibility depends on the operator skills. It requires intensive resource involvement. For epidemiological studies these methods are not suitable. The aim of our study was to clinically evaluate the validity and reproducibility of a new automatic device for measurement of pulse wave velocity that can be used in such studies. Methods In 44 subjects including normal healthy control and patients with coronary artery disease, heart brachial, heart ankle, brachial ankle and carotid femoral pulse wave velocities were recorded by using a new oscillometric device. Lead I and II electrocardiogram and pressure curves were simultaneously recorded. Two observers recorded the pulse wave velocity for validation and one observer recorded the velocity on two occasions for reproducibility. Results and Discussion Pulse wave velocity and arterial stiffness index were recorded in 24 control and 20 coronary artery disease patients. All the velocities were significantly high in coronary artery disease patients. There was highly significant correlation between the values noted by the two observers with low standard deviation. The Pearson's correlation coefficient for various velocities ranged from (r = 0.88–0.90 with (p Conclusion The new device "PeriScope" based on oscillometric technique has been found to be a simple, non-invasive and reproducible device for the assessment of pulse wave velocity and can be used to determine arterial stiffness in large population based studies.

  10. Integration of a capacitive pressure sensing system into the outer catheter wall for coronary artery FFR measurements

    Science.gov (United States)

    Stam, Frank; Kuisma, Heikki; Gao, Feng; Saarilahti, Jaakko; Gomes Martins, David; Kärkkäinen, Anu; Marrinan, Brendan; Pintal, Sebastian

    2017-05-01

    The deadliest disease in the world is coronary artery disease (CAD), which is related to a narrowing (stenosis) of blood vessels due to fatty deposits, plaque, on the arterial walls. The level of stenosis in the coronary arteries can be assessed by Fractional Flow Reserve (FFR) measurements. This involves determining the ratio between the maximum achievable blood flow in a diseased coronary artery and the theoretical maximum flow in a normal coronary artery. The blood flow is represented by a pressure drop, thus a pressure wire or pressure sensor integrated in a catheter can be used to calculate the ratio between the coronary pressure distal to the stenosis and the normal coronary pressure. A 2 Fr (0.67mm) outer diameter catheter was used, which required a high level of microelectronics miniaturisation to fit a pressure sensing system into the outer wall. The catheter has an eccentric guidewire lumen with a diameter of 0.43mm, which implies that the thickest catheter wall section provides less than 210 microns height for flex assembly integration consisting of two dies, a capacitive MEMS pressure sensor and an ASIC. In order to achieve this a very thin circuit flex was used, and the two chips were thinned down to 75 microns and flip chip mounted face down on the flex. Many challenges were involved in obtaining a flex layout that could wrap into a small tube without getting the dies damaged, while still maintaining enough flexibility for the catheter to navigate the arterial system.

  11. Technical Note: Measurement of common carotid artery lumen dynamics using black-blood MR cine imaging.

    Science.gov (United States)

    Dai, Erpeng; Dong, Li; Zhang, Zhe; Li, Lyu; Zhang, Hui; Zhao, Xihai; Wang, Jinnan; Yuan, Chun; Guo, Hua

    2017-03-01

    To demonstrate the feasibility of measuring the common carotid artery (CCA) lumen dynamics using a black-blood cine (BB-cine) imaging method. Motion-sensitized driven-equilibrium (MSDE) prepared spoiled gradient sequence was used for the BB-cine imaging. CCAs of eleven healthy volunteers were studied using this method. Lumen dynamics, including lumen area evolution waveforms and distension values, were measured and evaluated by comparing this method with bright-blood cine (BrB-cine) imaging. Compared with the BrB-cine images, flow artifacts were effectively suppressed in the BB-cine images. BrB-cine images generally show larger lumen areas than BB-cine images. The lumen area waveforms and distension measurements from BB-cine imaging showed smaller variances among different subjects than BrB-cine imaging. The proposed BB-cine imaging technique can suppress the flow artifacts effectively and reduce the partial volume effects from the vessel wall. This might allow more accurate lumen dynamics measurements than traditional BrB-cine imaging, which may further be valuable for investigating biomechanical and functional properties of the cardiovascular system. © 2017 American Association of Physicists in Medicine.

  12. Validity and reliability of Doppler ultrasonography and direct arterial blood pressure measurements in anaesthetized dogs weighing less than 5 kg.

    Science.gov (United States)

    Moll, Xavier; Aguilar, Adria; García, Felix; Ferrer, Rosa; Andaluz, Anna

    2017-09-15

    To assess the validity and reliability of Doppler ultrasonography (DOP) as compared with invasive arterial blood pressure measurements in anaesthetized dogs weighing less than 5 kg. Controlled, prospective, clinical study. A total of 41 privately owned dogs weighing less than 5 kg. The dogs were anaesthetized, and an intra-arterial catheter was placed aseptically in the dorsal pedal artery of the pelvic limb to perform invasive blood pressure (IBP) measurement. The contralateral metatarsal surface of the foot was clipped in order to perform DOP. Both techniques were used to record blood pressure measurements every 5 minutes during surgical procedures. The blood pressure measurements were categorized into two groups: hypotensive [mean arterial pressure (MAP) blood pressure (SAP) and MAP of IBP measurements. The closest agreement between the two techniques was found for SAP; the bias was 8.8, and limits of agreement (LOA) were -32.9 and 50.4. Similar results were observed when the IBP technique was categorized. The closest agreement was for SAP in animals categorized as normotensive; the bias was 8.2, and LOAs were -32.8 and 49.2. The level of agreement between DOP and IBP did not meet the ACVIM recommendations. Our results suggest there is poor agreement between DOP and IBP measurements in anaesthetized dogs weighing less than 5 kg. Hence, the use of DOP in these animals could be misleading. Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.

  13. Medida da pressão arterial em gestante Toma de la presión arterial en embarazadas Blood pressure measurement in pregnancy

    Directory of Open Access Journals (Sweden)

    Sonia M. Junqueira V. de Oliveira

    1997-07-01

    Full Text Available Trata-se de revisão da literatura à respeito da medida indireta da pressão arterial (P A em gestante normotensa. Aborda as modificações ocorridas na pressão arterial sistólica e diastólica decorrentes da gravidez. São discutidos aspectos polêmicos no procedimento de medida da P A, como por exemplo qual a fase dos sons de Korotkoff (fase quatro ou cinco que representa melhor a pressão diastólica e o uso da Monitorização Ambulatorial da Pressão Arterial. Enfatiza as recomendações de diferentes sociedades (American Heart Association, British Hypertension Society, Australasian Society, National High Blood Pressure Education Program e World Health Organization.Se trata de una revisión de la literatura con respeto a la toma indirecta de la presión arterial (PA en embarazadas normotensas. Se describen los cámbios que ocurrer en la presión arterial sistólica y diastólica a causa del embarazo. Son discutidos aspectos polémicos en el procedimiento de la toma de la PA, como por ejemplo: cuál es la fase de los sonidos de Korotkoff (fases cuatro o cinco que representa mejor la presión sistólica. Se enfatizan las recomendaciones de diferentes sociedades (American Heart Association, British Hypertension Society, Australasian Society, National High Blood Pressure Education Program and World Health Organization.This study deals with the review of the literature regarding the indirect blood pressure measurement in normal pregnant women. It shows the changes that happened whith the blood pressure due to pregnancy. Polemical aspects in the procedure of blood pressure measurement are discussed; for example, which one of the Korotkoff phases (4 or 5 that better represent the diastolic blood pressure and the use of Ambulatory Blood Pressure Monitoring in pregnancy. The recommendations from different societies are emphasized (American Heart Association, British Hypertension Society, Australasian Society, National High Blood Pressure Education

  14. Arterial input functions (AIFs) measured directly from arteries with low and standard doses of contrast agent, and AIFs derived from reference tissues.

    Science.gov (United States)

    Wang, Shiyang; Fan, Xiaobing; Medved, Milica; Pineda, Federico D; Yousuf, Ambereen; Oto, Aytekin; Karczmar, Gregory S

    2016-02-01

    Measurements of arterial input function (AIF) can have large systematic errors at standard contrast agent doses in dynamic contrast enhanced MRI (DCE-MRI). We compared measured AIFs from low dose (AIFLD) and standard dose (AIFSD) contrast agent injections, as well as the AIF derived from a muscle reference tissue and artery (AIFref). Twenty-two prostate cancer patients underwent DCE-MRI. Data were acquired on a 3T scanner using an mDixon sequence. Gadobenate dimeglumine was injected twice, at doses of 0.015 and 0.085 mmol/kg. Directly measured AIFs were fitted with empirical mathematical models (EMMs) and compared to the AIF derived from a muscle reference tissue (AIFref). EMMs accurately fitted the AIFs. The 1st and 2nd pass peaks were visualized in AIFLD, but not in AIFSD, thus the peak and shape of AIFSD could not be accurately measured directly. The average scaling factor between AIFSD and AIFLD in the washout phase was only 56% of the contrast dose ratio (~6:1). The shape and magnitude of AIFref closely approximated that of AIFLD after empirically determined dose-dependent normalization. This suggests that AIFref may be a good approximation of the local AIF. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. A poor correlation exists between oscillometric and radial arterial blood pressure as measured by the Philips MP90 monitor.

    Science.gov (United States)

    Mireles, Samuel A; Jaffe, Richard A; Drover, David R; Brock-Utne, John G

    2009-06-01

    In anesthesia and critical care, invasive arterial blood pressure monitoring is the gold standard against which other methods of monitoring are compared. In this assessment of the Philips MP90 monitor, the objective was to determine whether or not oscillometric measurements were within the accuracy standards set by the Association for the Advancement of Medical Instrumentation (AAMI) and the British Hypertension Society (BHS). Three hundred and one invasive and noninvasive paired measurements were obtained from eleven adult patients on the neurosurgical service at Stanford University Medical Center. Bland-Altman plots were created to assess agreement between the two measurement systems. Paired correlation analysis, bias and precision calculations were performed. Oscillometric blood pressure measurements correlated with arterial measurements yielding Pearson r values of 0.68, 0.67 and 0.62 for systolic, diastolic and mean pressures, respectively (P < 0.01.) Mean differences with 95% confidence intervals were -3.8 mmHg +/- 13.6, -2.4 mmHg +/- 10.0, and 4.0 mmHg +/- 13.1 for systolic, diastolic and mean pressures, respectively. The mean difference for these measurements was arterial pressure, and a grade "C" for diastolic pressure, with the highest possible grade level being "A." There was a poor correlation between noninvasive and invasive measurements of arterial blood pressure as measured with a cuff and radial arterial cannula using the Philips MP90 monitor. These inaccuracies could lead to unnecessary interventions, or lack of appropriate interventions in anesthetic management. Further study is needed to specify the absolute inaccuracy of the monitor, and to determine if accuracy between the two methods varies with patient co

  16. Effect of Electron Seeding on Experimentally Measured Multipactor Discharge Threshold

    Science.gov (United States)

    Noland, Jonathan; Graves, Timothy; Lemon, Colby; Looper, Mark; Farkas, Alex

    2012-10-01

    Multipactor is a vacuum phenomenon in which electrons, moving in resonance with an externally applied electric field, impact material surfaces. If the number of secondary electrons created per primary electron impact averages more than unity, the resonant interaction can lead to an electron avalanche. Multipactor is a generally undesirable phenomenon, as it can cause local heating, absorb power, or cause detuning of RF circuits. In order to increase the probability of multipactor initiation, test facilities often employ various seeding sources such as radioactive sources (Cesium 137, Strontium 90), electron guns, or photon sources. Even with these sources, the voltage for multipactor initiation is not certain as parameters such as material type, RF pulse length, and device wall thickness can all affect seed electron flux and energy in critical gap regions, and hence the measured voltage threshold. This study investigates the effects of seed electron source type (e.g., photons versus beta particles), material type, gap size, and RF pulse length variation on multipactor threshold. In addition to the experimental work, GEANT4 simulations will be used to estimate the production rate of low energy electrons (< 5 keV) by high energy electrons and photons. A comparison of the experimental fluxes to the typical energetic photon and particle fluxes experienced by spacecraft in various orbits will also be made. Initial results indicate that for a simple, parallel plate device made of aluminum, there is no threshold variation (with seed electrons versus with no seed electrons) under continuous-wave RF exposure.

  17. Experimental Measurements of Prestressed Masonry with using Sliding Joint

    Directory of Open Access Journals (Sweden)

    Stara Marie

    2014-06-01

    Full Text Available Contribution deals with experimental measurements of deformations in the place exposed to local load caused by additional pre-stressing. The measurements are made at the masonry corner built in the laboratory equipment. The laboratory equipment was designed at Faculty of Civil Engineering VŠB-Technical University of Ostrava for measurement tri-axial stress-strain conditions in masonry. In this masonry corner two pre-stressing bars are placed. These bars are in different height and are anchored to the anchor plates, which transfer pre-stressing forces to the masonry. The specimen for laboratory testing is performed in the proportion to the reality of 1:1. In the bottom part masonry is inserted asphalt strip. It operates in the masonry like a sliding joint and reduces the shear stress at interface between concrete and masonry structures. The results are compared with the results of masonry without the use of sliding joints, including comment on the effect of sliding joints on the pre-stressing masonry structures.

  18. Experimental measurement-device-independent quantum random-number generation

    Science.gov (United States)

    Nie, You-Qi; Guan, Jian-Yu; Zhou, Hongyi; Zhang, Qiang; Ma, Xiongfeng; Zhang, Jun; Pan, Jian-Wei

    2016-12-01

    The randomness from a quantum random-number generator (QRNG) relies on the accurate characterization of its devices. However, device imperfections and inaccurate characterizations can result in wrong entropy estimation and bias in practice, which highly affects the genuine randomness generation and may even induce the disappearance of quantum randomness in an extreme case. Here we experimentally demonstrate a measurement-device-independent (MDI) QRNG based on time-bin encoding to achieve certified quantum randomness even when the measurement devices are uncharacterized and untrusted. The MDI-QRNG is randomly switched between the regular randomness generation mode and a test mode, in which four quantum states are randomly prepared to perform measurement tomography in real time. With a clock rate of 25 MHz, the MDI-QRNG generates a final random bit rate of 5.7 kbps. Such implementation with an all-fiber setup provides an approach to construct a fully integrated MDI-QRNG with trusted but error-prone devices in practice.

  19. Experimental measurements of motion cue effects on STOL approach tasks

    Science.gov (United States)

    Ringland, R. F.; Stapleford, R. L.

    1972-01-01

    An experimental program to investigate the effects of motion cues on STOL approach is presented. The simulator used was the Six-Degrees-of-Freedom Motion Simulator (S.01) at Ames Research Center of NASA which has ?2.7 m travel longitudinally and laterally and ?2.5 m travel vertically. Three major experiments, characterized as tracking tasks, were conducted under fixed and moving base conditions: (1) A simulated IFR approach of the Augmentor Wing Jet STOL Research Aircraft (AWJSRA), (2) a simulated VFR task with the same aircraft, and (3) a single-axis task having only linear acceleration as the motion cue. Tracking performance was measured in terms of the variances of several motion variables, pilot vehicle describing functions, and pilot commentary.

  20. Experimental Measurements of Diffusivity of Vapors through Porous Substrates

    Science.gov (United States)

    Li, Hongyang; Rincon, Carlos; Bowden, Elizabeth; Zand, Ali; Sikorski, Yuri; Sanders, Matthew; Navaz, Homayun

    2007-05-01

    The release of numerous toxic chemicals, such as hydrocarbons, pesticides, chemical warfare agents, etc.; into soil, subsurface, concrete, brick and asphalt poses a great threat to the biosphere environment. The quantification and extent of spread of these chemicals has primary importance for carrying out the remediation work. There are several well known spread mechanisms which govern the mass transport in porous media. They include various regimes of liquid and vapor transport/diffusion. Modeling the transport of vapors in porous substrates requires the knowledge of the diffusivity of each particular vapor in each substrate. We present a simple, effective and inexpensive experimental method and apparatus for measurement of vapor diffusivity in porous media. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.OSS07.P1.24

  1. Experimental arrangement to measure dispersion in optical fiber devices

    Energy Technology Data Exchange (ETDEWEB)

    Armas Rivera, Ivan [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias de la Electronica (Mexico); Beltran Perez, Georgina; Castillo Mixcoatl, Juan; Munoz Aguirre, Severino [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Fisico Matematicas (Mexico); Zaca Moran, Placido, E-mail: ivan_rr1@hotmail.com [Benemerita Universidad Autonoma de Puebla, Fisicoquimica de Materiales ICUAP (Mexico)

    2011-01-01

    Dispersion is a quite important parameter in systems based on optical fiber, especially in pulsed emission lasers, where the temporal width is affected by such parameter. Therefore, it is necessary to consider the dispersion provoked by each component in the cavity. There are various experimental interferometric arrangements to evaluate this parameter. Generally, these systems modify the wavelength to obtain information about the n({lambda}) dependency, which is contained in the interferogram phase. However, this makes the system quite slow and it requires tunable and narrow bandwidth laser sources. In the present work, results obtained from an arrangement based on Mach-Zehnder interferometer where one of the arms is the optical fiber under study, while the reference one is air, are presented. In order to determine the n({lambda}) dependency, a wide spectrum light source was used in the wavelength range of interest. The phase information was evaluated from the interferometric signal measured by an optical spectrum analyzer.

  2. Experimental measurement-device-independent quantum digital signatures.

    Science.gov (United States)

    Roberts, G L; Lucamarini, M; Yuan, Z L; Dynes, J F; Comandar, L C; Sharpe, A W; Shields, A J; Curty, M; Puthoor, I V; Andersson, E

    2017-10-23

    The development of quantum networks will be paramount towards practical and secure telecommunications. These networks will need to sign and distribute information between many parties with information-theoretic security, requiring both quantum digital signatures (QDS) and quantum key distribution (QKD). Here, we introduce and experimentally realise a quantum network architecture, where the nodes are fully connected using a minimum amount of physical links. The central node of the network can act either as a totally untrusted relay, connecting the end users via the recently introduced measurement-device-independent (MDI)-QKD, or as a trusted recipient directly communicating with the end users via QKD. Using this network, we perform a proof-of-principle demonstration of QDS mediated by MDI-QKD. For that, we devised an efficient protocol to distil multiple signatures from the same block of data, thus reducing the statistical fluctuations in the sample and greatly enhancing the final QDS rate in the finite-size scenario.

  3. Experimental measurement on movement of spiral-type capsule endoscope.

    Science.gov (United States)

    Yang, Wanan; Dai, Houde; He, Yong; Qin, Fengqing

    2016-01-01

    Wireless capsule endoscope achieved great success, however, the maneuvering of wireless capsule endoscope is challenging at present. A magnetic driving instrument, including two bar magnets, a stepper motor, a motor driver, a motor controller, and a power supplier, was developed to generate rotational magnetic fields. Permanent magnet ring, magnetized as S and N poles radially and mounted spiral structure on the surface, acted as a capsule. The maximum torque passing to the capsule, rotational synchronization of capsule and motor, and the translational speed of capsule, were measured in ex vivo porcine large intestine. The experimental results illustrate that the rotational movement of the spiral-type capsule in the intestine is feasible and the cost of the magnetic driving equipment is low. As a result, the solution is promising in the future controllability.

  4. Effects of Filtering on Experimental Blast Overpressure Measurements.

    Science.gov (United States)

    Alphonse, Vanessa D; Kemper, Andrew R; Duma, Stefan M

    2015-01-01

    When access to live-fire test facilities is limited, experimental studies of blast-related injuries necessitate the use of a shock tube or Advanced Blast Simulator (ABS) to mimic free-field blast overpressure. However, modeling blast overpressure in a laboratory setting potentially introduces experimental artifacts in measured responses. Due to the high sampling rates required to capture a blast overpressure event, proximity to alternating current (AC-powered electronics) and poorly strain-relieved or unshielded wires can result in artifacts in the recorded overpressure trace. Data in this study were collected for tests conducted on an empty ABS (“Empty Tube”) using high frequency pressure sensors specifically designed for blast loading rates (n=5). Additionally, intraocular overpressure data (“IOP”) were collected for porcine eyes potted inside synthetic orbits located inside the ABS using an unshielded miniature pressure sensor (n=3). All tests were conducted at a 30 psi static overpressure level. A 4th order phaseless low pass Butterworth software filter was applied to the data. Various cutoff frequencies were examined to determine if the raw shock wave parameters values could be preserved while eliminating noise and artifacts. A Fast Fourier Transform (FFT) was applied to each test to examine the frequency spectra of the raw and filtered signals. Shock wave parameters (time of arrival, peak overpressure, positive duration, and positive impulse) were quantified using a custom MATLAB® script. Lower cutoff frequencies attenuated the raw signal, effectively decreasing the peak overpressure and increasing the positive duration. Rise time was not preserved the filtered data. A CFC 6000 filter preserved the remaining shock wave parameters within ±2.5% of the average raw values for the Empty Tube test data. A CFC 7000 filter removed experimental high-frequency artifacts and preserved the remaining shock wave parameters within ±2.5% of the average raw values for

  5. In vivo experimental stroke and in vitro organ culture induce similar changes in vasoconstrictor receptors and intracellular calcium handling in rat cerebral arteries

    DEFF Research Database (Denmark)

    Povlsen, Gro Klitgaard; Waldsee, Roya; Ahnstedt, Hilda

    2012-01-01

    after stroke. Here, we evaluate changes of ET(B) and 5-HT(1B) receptors, intracellular calcium levels, and calcium channel expression in rat middle cerebral artery (MCA) after focal cerebral ischemia and in vitro organ culture, a proposed model of vasoconstrictor receptor changes after stroke. Rats were...... subjected to 2 h MCA occlusion followed by reperfusion for 1 or 24 h. Alternatively, MCAs from naïve rats were cultured for 1 or 24 h. ET(B) and 5-HT(1B) receptor-mediated contractions were evaluated by wire myography. Receptor and channel expressions were measured by real-time PCR and immunohistochemistry....... Intracellular calcium was measured by FURA-2. Expression and contractile functions of ET(B) and 5-HT(1B) receptors were strongly upregulated and slightly downregulated, respectively, 24 h after experimental stroke or organ culture. ET(B) receptor-mediated contraction was mediated by calcium from intracellular...

  6. 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.

  7. Measuring Diagnostic Stand for Experimental Researches in Technology Machining

    Directory of Open Access Journals (Sweden)

    A. E. Dreval'

    2014-01-01

    Full Text Available The paper reviews applied techniques, methods, and structure of the control and measuring means to conduct experimental and scientific researches of cutting processes. Existing research methods in cutting the metals are divided by features, such as essence of methods, the number of records of physical indicators, the number of studied factors, duration of tests. The groups of methods are briefly characterized.The chair "Tool Engineering and Technologies" of BMSTU developed and made a diagnostic stand of control and measurements for conducting research activities in the field of materials processing technology by cutting to define rational technological decisions, when machining, and carry out an analysis of efficiency and economic feasibility of made decisions. The diagnostic stand contains modern the electronic equipment. Record of measuring parameters is made in real time with a possibility for visual representation of read results and mathematical and statistical processing of measurement results. The stand can be used in research laboratories of machine-building enterprises, laboratories of higher education institutions, and other scientific divisions.The paper presents a justification that the stand is reasonable to use for the following: completion and choice of rational cutting modes, workability assessment of new constructional materials, technical and operational characteristics of the processed surfaces, and operational properties of the cutting tools of various producers, choice of optimum geometrical parameters of the cutting tools and brands of the lubricant cooling technological means, as well as the energy consumption for the chosen machining process. The stand allows us to make an assessment of wear resistance and tribology-technical characteristics of tool materials, as well as an accuracy, rigidity, vibration stability of machines, both new and being in operation.

  8. Closure of digital arteries in high vascular tone states as demonstrated by measurement of systolic blood pressure in the fingers

    DEFF Research Database (Denmark)

    Krähenbühl, B; Nielsen, S L; Lassen, N A

    1977-01-01

    Finger systolic blood pressure (FSP) was measured indirectly in normal subjects and patients with primary Raynaud phenomenon by applying a thin-walled plastic cuff around the finger and a strain gauge more distally to detect volume changes. Inducing a high vascular tone in one or more fingers...... by direct cooling or intra-arterial noradrenaline infusion caused a marked drop in FSP in the exposed fingers, but not in the non-exposed fingers of the same hand. The fact that the non-exposed fingers retained the normal (arm systolic) pressure level is taken to indicate that palmar arch blood pressure...... also remained normal. In the high vascular tone state, a large transmural pressure difference must apparently be established before the digital arteries are forced open. The lowered opening pressure constitutes a manifestation of the closure phenomenon of the digital arteries described in patients...

  9. 3D Residual Stress Field in Arteries: Novel Inverse Method Based on Optical Full-field Measurements

    CERN Document Server

    Badel, Pierre; Avril, Stéphane; 10.1111/str.12008

    2013-01-01

    Arterial tissue consists of multiple structurally important constituents that have individual material properties and associated stress-free configurations that evolve over time. This gives rise to residual stresses contributing to the homoeostatic state of stress in vivo as well as adaptations to perturbed loads, disease or injury. The existence of residual stresses in an intact but load-free excised arterial segment suggests compressive and tensile stresses, respectively, in the inner and outer walls. Accordingly, an artery ring springs open into a sector after a radial cut. The measurement of the opening angle is commonly used to deduce the residual stresses, which are the stresses required to close back the ring. The opening angle method provides an average estimate of circumferential residual stresses but it gives no information on local distributions through the thickness and along the axial direction. To address this lack, a new method is proposed in this article to derive maps of residual stresses usi...

  10. Auscultatory versus oscillometric blood pressure measurement in patients with atrial fibrillation and arterial hypertension.

    Science.gov (United States)

    Šelmytė-Besusparė, Aistėja; Barysienė, Jūratė; Petrikonytė, Dovilė; Aidietis, Audrius; Marinskis, Germanas; Laucevičius, Aleksandras

    2017-03-23

    The aim of our study was to investigate the reliability of automated oscillometric blood pressure (BP) monitoring in the presence and absence of atrial fibrillation (AF) in hypertensive patients. BP was measured and compared in 71 randomly selected patients with AF and arterial hypertension diagnosis, 4 times each by auscultatory and oscillometric (Microlife BP A6 PC with AF detection system) methods. Study included 71 patients: 36 males (mean age 67.4 years) and 35 females (70.2 years). At the time of BP measuring procedure, 36 patients were in sinus rhythm (SR) and 35 in AF. In SR patients mean systolic blood pressure (SBP) was 132 ± 17.9 mmHg with auscultatory method (AM), 137.4 ± 19.4 mmHg with oscillometric method (OM); mean diastolic BP was 77.1 ± 10.9 mmHg (AM), 78.5 ± 12.2 mmHg (OM), in AF patients mean SBP was 127.5 ± 15.1 mmHg (AM), 133.6 ± 17.4 mmHg (OM); mean diastolic BP was 81.4 ± 9.9 mmHg (AM), 83.5 ± 11.8 mmHg (OM), p = 0.037. The averages of differences for SBP and DBP in sinus rhythm group were (-5.3 mmHg (95% limits of agreement -27.2 - 16.6)) and (-1.4 mmHg (95% limits of agreement -12.8 - 10.0)), respectively. In patients with AF the averages of differences for SBP and DBP were (-6.1 mmHg (95% limits of agreement -23.9 - 11.7)) and (-2.1 mmHg (95% limits of agreement -12.9 - 8.7)), respectively. The oscillometric device validated for patients with AF on average gives 5.3 mmHg higher systolic BP values for patients with SR and 6.3 mmHg higher BP values for patients with AF. However, the limits of agreement between two methods reveal wide range of random error rates which is a questionable topic in clinical practice, as it could possibly affect the treatment of arterial hypertension in patients with AF.

  11. [Principles and experimental analysis of a measuring system for measuring spacesuit joint's damping parameters].

    Science.gov (United States)

    Wang, Hao; Jin, Ming-he; Liu, Hong; Gao, Xiao-hui; Li, Tan-qiu; Zhao, Yong-jun

    2003-10-01

    To measure the damping parameters of the spacesuit joint. The principles of the passive robot system for measuring spacesuit joint's damping parameters were presented. Basing on its special mechanical structure, a 3 DOF model of the flexible IVA (intra-vehicular activity) spacesuit's sleeve was built. The optimal approximation of inverse calculation based on 6 dimension space interval was described. The damping parameters of an actual IVA spacesuit's sleeve were measured on the actual testbed. Also, the potential application of the measuring system was discussed. The model of spacesuit sleeve and the forward/inverse kinematics were proved by experimental measurements and real time 3D simulation. The principles and the proposed method of the measurement were testified.

  12. Mechanical Recanalization of Cerebral Artery Embolic Occlusion Using a Self-Expanding Stent: Experimental Analysis in Canine Model

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jin Woo; Kim, Snag Joon; Lee, Deok Hee; Suh, Dae Chul [Dept. of Radiology and Research Institute of Radiology, Asan Medical Center, Ulsan University College of Medicine, Seoul (Korea, Republic of)

    2011-07-15

    To evaluate the feasibility of a self-expanding stent for acute embolic occlusion, and recanalization mechanism by histologic examination. Five mongrel dogs were used as study subjects. Each vertebral artery was occluded, and a self-expanding stent was used for recanalization. We evaluated the technical success rate for the placement of the stent to the targeted vessel, the recanalization rate, and residual stenosis. We obtained two specimens of the stented vertebral arteries for histologic evaluation. One dog died of an unknown cause during the induction of anesthesia. In two dogs, only one side of the vertebral artery was used, whereas both vertebral arteries were used in the remaining dogs. A total of six vertebral arteries were successfully occluded. The technical success rate for stenting without complication was 66.7%. The immediate recanalization rate after stenting was 100%. The residual stenosis was 35.6 {+-} 18.6%. On microscopic examination, the stent concentrically displaced the clot and the clot was captured between the stent mesh and arterial wall. Self-expanding stents were effective in revascularizing the cerebrovascular embolic occlusion. The self-expanding stent seemed to achieve recanalization by pushing the clot to the arterial wall and capturing the clot between the stent mesh and arterial wall.

  13. Roles of myocardial blood volume and flow in coronary artery disease: an experimental MRI study at rest and during hyperemia

    Energy Technology Data Exchange (ETDEWEB)

    McCommis, Kyle S.; Goldstein, Thomas A.; Pilgram, Thomas [Washington University School of Medicine, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Abendschein, Dana R. [Washington University School of Medicine, Center for Cardiovascular Research, St. Louis, MO (United States); Misselwitz, Bernd [Bayer Schering Pharma AG, Berlin (Germany); Gropler, Robert J. [Washington University School of Medicine, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Washington University School of Medicine, Center for Cardiovascular Research, St. Louis, MO (United States); Zheng, Jie [Washington University School of Medicine, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Cardiovascular Imaging Lab, St. Louis, MO (United States)

    2010-08-15

    To validate fast perfusion mapping techniques in a setting of coronary artery stenosis, and to further assess the relationship of absolute myocardial blood volume (MBV) and blood flow (MBF) to global myocardial oxygen demand. A group of 27 mongrel dogs were divided into 10 controls and 17 with acute coronary stenosis. On 1.5-T MRI, first-pass perfusion imaging with a bolus injection of a blood-pool contrast agent was performed to determine myocardial perfusion both at rest and during either dipyridamole-induced vasodilation or dobutamine-induced stress. Regional values of MBF and MBV were quantified by using a fast mapping technique. Color microspheres and {sup 99m}Tc-labeled red blood cells were injected to obtain respective gold standards. Microsphere-measured MBF and {sup 99m}Tc-measured MBV reference values correlated well with the MR results. Given the same changes in MBF, changes in MBV are twofold greater with dobutamine than with dipyridamole. Under dobutamine stress, MBV shows better association with total myocardial oxygen demand than MBF. Coronary stenosis progressively reduced this association in the presence of increased stenosis severity. MR first-pass perfusion can rapidly estimate regional MBF and MBV. Absolute quantification of MBV may add additional information on stenosis severity and myocardial viability compared with standard qualitative clinical evaluations of myocardial perfusion. (orig.)

  14. QT interval derived measurements in patients with cardiac syndrome X compared to coronary artery disease

    Directory of Open Access Journals (Sweden)

    Mohamed Faisal Lutfi

    2016-09-01

    Full Text Available Previous studies assessing effect of ischemia on ventricular repolarization are mostly directed towards patients with coronary artery disease (CAD; however, similar reports on cardiac syndrome X (CSX are scarce. Whether microvascular dysfunction of CSX and ischemia induced by CAD produce comparable effect on ventricular repolarization is unclear and deserve further studies. In the present study, ECG measures of ventricular repolarization were compared between CAD and CSX patients (40 subjects in each group. Following evaluation of sociodemographic characteristics, medical and past medical history, a resting ECG was used to assess measurements of ventricular repolarization in each patient, namely, QT interval (QT, corrected QT interval (QTc, QT dispersion (QTd, corrected QT dispersion (QTcd, adjacent QT dispersion (AdQTd, QT dispersion ratio (QTdR, JT dispersion (JTd and Corrected JT dispersion (JTcd. Results showed comparable QT intervals and QTd in CAD and CSX patients even after adjustment for the possible variations in gender, age and body mass index of the studied groups. Although JTd was increased in CSX subjects (26.6±7.2 ms compared with CAD patients (22.7±6.5 ms, p = 0.019, statistical significance disappeared after correcting JT for variations in heart rate. QT and QTc were significantly below 440 ms in CAD as well as CSX patients (p < 0.001. In contrast, maximum QTd, maximum QTcd and AdQTd of CAD and CSX patients were significantly above 440 ms (p < 0.001. The means of JTd and JTcd were significantly above 22 ms and 24 ms respectively (p < 0.001, p = 0.001 in CSX but not CAD patients (p = 0.529, p = 0.281. The present findings clearly demonstrate comparable measures of ventricular repolarization in CAD and CSX patients and consequently the risk of cardiac events.

  15. Stability of MR brain-perfusion measurement using arterial spin labeling

    Energy Technology Data Exchange (ETDEWEB)

    Petr, Jan; Hofheinz, Frank; Platzek, Ivan; Schramm, Georg; Van Den Hoff, Jorg [Helmholtz-Center Dresden-Rossendorf, PET Center, Institute of Radiopharmaceutical Cancer Research (Germany)

    2015-05-18

    Arterial spin labeling (ASL) is an MR technique for assessment of cerebral blood flow (CBF) that does not require use of contrast agents which makes it a less invasive alternative to the 15O-H2O-PET measurement. The repeatability of ASL has been studied extensively but mainly in young healthy volunteers. We have tested repeatability of ASL under realistic clinical conditions in elderly brain tumor patients acquired with a Philips Ingenuity TF PET/MR in the context of an ongoing 11C-Methionine PET/MR study. Twenty three patients (age 54.8±13.0 y) were scanned on two or more session. The patients underwent 6 weeks of concurrent radiochemotherapy with Temozolomide between the first session and second measurement. The mean relative difference of gray matter CBF was 18.6% between the first two session and 13.0% for the second session and further on. The mean gray matter CBF was 46.6±7.2 mL/min/100 g on the first sessions and there was a significant decrease of 9.8% between first and second session (p=0.027). In summary, the ASL presents measurement of CBF with reasonable repeatability also in elderly patients under clinical conditions when it is not possible to control for all sources of variation. Significant decrease of CBF in healthy tissue was observed after the radiochemotherapy. Prospectively, the ASL data together with the also acquired 11C-Methionine PET will be evaluated regarding their separate and combined ability to predict patient outcome and effectiveness of the performed radiochemotherapy.

  16. QT Interval Derived Measurements in Patients with Cardiac Syndrome X Compared to Coronary Artery Disease.

    Science.gov (United States)

    Lutfi, Mohamed F

    2016-01-01

    Previous studies assessing effect of ischemia on ventricular repolarization are mostly directed toward patients with coronary artery disease (CAD); however, similar reports on cardiac syndrome X (CSX) are scarce. Whether microvascular dysfunction of CSX and ischemia induced by CAD produce comparable effect on ventricular repolarization is unclear and deserve further studies. In the present study, ECG measures of ventricular repolarization were compared between CAD and CSX patients (40 subjects in each group). Following evaluation of sociodemographic characteristics, medical and past medical history, a resting ECG was used to assess measurements of ventricular repolarization in each patient, namely, QT interval (QT), corrected QT interval (QTc), QT dispersion (QTd), corrected QT dispersion (QTcd), adjacent QT dispersion (AdQTd), QT dispersion ratio (QTdR), JT dispersion (JTd), and Corrected JT dispersion (JTcd). Results showed comparable QT intervals and QTd in CAD and CSX patients even after adjustment for the possible variations in gender, age and body mass index of the studied groups. Although JTd was increased in CSX subjects (26.6 ± 7.2 ms) compared with CAD patients (22.7 ± 6.5 ms, p = 0.019), statistical significance disappeared after correcting JT for variations in heart rate. QT and QTc were significantly below 440 ms in CAD as well as CSX patients (p < 0.001). In contrast, maximum QTd, maximum QTcd and AdQTd of CAD and CSX patients were significantly above 440 ms (p < 0.001). The means of JTd and JTcd were significantly above 22 ms and 24 ms respectively (p < 0.001, p = 0.001) in CSX but not CAD patients (p = 0.529, p = 0.281). The present findings clearly demonstrate comparable measures of ventricular repolarization in CAD and CSX patients and consequently an equal risk of cardiac events in both groups.

  17. Myocardial Deformation Measured by 3-Dimensional Speckle Tracking in Children and Adolescents With Systemic Arterial Hypertension.

    Science.gov (United States)

    Navarini, Susanne; Bellsham-Revell, Hannah; Chubb, Henry; Gu, Haotian; Sinha, Manish D; Simpson, John M

    2017-12-01

    Systemic arterial hypertension predisposes children to cardiovascular risk in childhood and adult life. Despite extensive study of left ventricular (LV) hypertrophy, detailed 3-dimensional strain analysis of cardiac function in hypertensive children has not been reported. The aim of this study was to evaluate LV mechanics (strain, twist, and torsion) in young patients with hypertension compared with a healthy control group and assess factors associated with functional measurements. Sixty-three patients (26 hypertension and 37 normotensive) were enrolled (mean age, 14.3 and 11.4 years; 54% men and 41% men, respectively). All children underwent clinical evaluation and echocardiographic examination, including 3-dimensional strain. There was no difference in LV volumes and ejection fraction between the groups. Myocardial deformation was significantly reduced in those with hypertension compared with controls. For hypertensive and normotensive groups, respectively, global longitudinal strain was -15.1±2.3 versus -18.5±1.9 ( P hypertensive and normotensive children, but children with hypertension had significantly lower strain indices. Whether reduced strain might predict future cardiovascular risk merits further longitudinal study. © 2017 American Heart Association, Inc.

  18. Experimental measurement on movement of spiral-type capsule endoscope

    Directory of Open Access Journals (Sweden)

    Yang W

    2016-01-01

    Full Text Available Wanan Yang,1 Houde Dai,2 Yong He,1 Fengqing Qin1 1School of Computer and Information Engineering, Yibin University, Yibin, Sichuan, People's Republic of China; 2Quanzhou Institute of Equipment Manufacturing, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Quanzhou, People's Republic of China Abstract: Wireless capsule endoscope achieved great success, however, the maneuvering of wireless capsule endoscope is challenging at present. A magnetic driving instrument, including two bar magnets, a stepper motor, a motor driver, a motor controller, and a power supplier, was developed to generate rotational magnetic fields. Permanent magnet ring, magnetized as S and N poles radially and mounted spiral structure on the surface, acted as a capsule. The maximum torque passing to the capsule, rotational synchronization of capsule and motor, and the translational speed of capsule, were measured in ex vivo porcine large intestine. The experimental results illustrate that the rotational movement of the spiral-type capsule in the intestine is feasible and the cost of the magnetic driving equipment is low. As a result, the solution is promising in the future controllability. Keywords: wireless capsule endoscope, magnet ring, magnetic driving, spiral structure, torque  

  19. Uterine artery embolization: the only life saving measure in some obstetric cases

    OpenAIRE

    Asha N. Gokhale; Latika J. Chawla; Shridhar Khajindar

    2015-01-01

    Uterine artery embolization is a highly specialised and efficacious method that can be used prophylactically to reduce obstetric haemorrhage. Its use in modern obstetrics is currently limited to morbidly adherent placenta and acreta. This report presents a case where uterine artery embolization has been used as the primary treatment for obstetric haemorrhage in a patient with high risk for PPH where surgical management would not have been possible. We aim at highlighting the benefits of this ...

  20. Erythropoietin attenuates pulmonary vascular remodeling in experimental pulmonary arterial hypertension through interplay between endothelial progenitor cells and heme-oxygenase

    Directory of Open Access Journals (Sweden)

    Rosa L.E. Loon

    2015-08-01

    Full Text Available BackgroundPulmonary arterial hypertension (PAH is a pulmonary vascular disease with a high mortality, characterized by typical angio-proliferative lesions. Erythropoietin (EPO attenuates pulmonary vascular remodeling in PAH. We postulated that EPO acts through mobilization of endothelial progenitor cells (EPCs and activation of the cytoprotective enzyme heme oxygenase-1 (HO1.MethodsRats with flow-associated PAH, resembling pediatric PAH, were treated with HO-1 inducer EPO in the presence or absence of the selective HO-activity-inhibitor tin-mesoporphyrin (SnMP. HO-activity, circulating EPCs and pulmonary vascular lesions were assessed after 3 weeks.ResultsIn PAH-rats, circulating EPCs were decreased and HO-activity was increased compared to control. EPO-treatment restored circulating EPCs and improved pulmonary vascular remodeling, as shown by a reduced wall thickness and occlusion rate of the intra-acinar vessels. Inhibition of HO-activity with SnMP aggravated PAH. Moreover, SnMP treatment abrogated EPO-induced amelioration of pulmonary vascular remodeling, while surprisingly further increasing circulating EPCs as compared with EPO alone.ConclusionsIn experimental PAH, EPO treatment restored the number of circulating EPC’s to control level, improved pulmonary vascular remodeling, and showed important interplay with HO-activity. Inhibition of increased HO-activity in PAH-rats exacerbated progression of pulmonary vascular remodeling, despite the presence of restored numbers of circulating EPC’s. We suggest that both EPO-induced HO1 and EPCs are promising targets to ameliorate the pulmonary vasculature in PAH.

  1. [Concordance between 3 methods of measurement the ankle-brachial index to diagnose peripheral artery disease].

    Science.gov (United States)

    Forés, Rosa; Alzamora, Maria Teresa; Pera, Guillem; Torán, Pere; Urrea, Magalí; Heras, Antonio

    2014-10-21

    To determine the concordance of the ankle-brachial index (ABI) determined by automatic measurements (sphygmomanometer Omron and the triple cuff device) using doppler as the gold-standard, computing as well as sensitivity and specificity. ARTPER population cohort subjects, classified as peripheral arterial disease (PAD) if ABI<0.9, calcified if ABI≥1.4 and healthy otherwise. To asses concordance we used kappa index using the 3 categories and the intraclass correlation coefficient (ICC) for ABI continuous values. Eighty-eight participants, 52% women, 57-87 years. It was possible to calculate the ABI using doppler for 100%, 97% using Omron and 95% using triple. ABI means (standard deviation) were: doppler 1.089 (0.236), Omron 1.082 (0.110), triple 1.146 (0.134), with poor agreement (ICC doppler/Omron=0.27, doppler/triple=0.13, and triple/Omron=0.39). Categorizing ABI as PAD-healthy-calcified 13.6% (doppler), 6.8% (Omron) and 3.4% (triple) were PAD and 9.1% (doppler), 1.1% (Omron) and 9.1% (triple) were calcified. Kappa indexes were weak (doppler/Omron=0.22, doppler/triple=0.01, triple/Omron=0.17). Both triple and Omron were highly specific (97%) but had very low sensitivity (8 and 33%, respectively) compared to doppler. Concordance of ABI automatic measurements as Omron and triple with doppler was poor, and they do not seem suitable for screening for PAD in primary care consultations. Copyright © 2013 Elsevier España, S.L.U. All rights reserved.

  2. Closure of digital arteries in high vascular tone states as demonstrated by measurement of systolic blood pressure in the fingers

    DEFF Research Database (Denmark)

    Krähenbühl, B; Nielsen, S L; Lassen, N A

    1977-01-01

    with vasospastic arterial disease. It implies an underestimation of palmar arch systolic pressure measured indirectly on the fingers. FSP measured under these circumstances may be taken as an estimate of the vascular tone, and can be employed in diagnosis and quantification of vasospastic disorders.......Finger systolic blood pressure (FSP) was measured indirectly in normal subjects and patients with primary Raynaud phenomenon by applying a thin-walled plastic cuff around the finger and a strain gauge more distally to detect volume changes. Inducing a high vascular tone in one or more fingers...... by direct cooling or intra-arterial noradrenaline infusion caused a marked drop in FSP in the exposed fingers, but not in the non-exposed fingers of the same hand. The fact that the non-exposed fingers retained the normal (arm systolic) pressure level is taken to indicate that palmar arch blood pressure...

  3. Effects of various factors on Doppler ultrasonographic measurements of radial and coccygeal arterial blood pressure in privately owned, conscious cats.

    Science.gov (United States)

    Whittemore, Jacqueline C; Nystrom, Michael R; Mawby, Dianne I

    2017-04-01

    OBJECTIVE To assess the effects of age, body condition score (BCS), and muscle condition score (MCS) on radial and coccygeal systolic arterial blood pressure (SAP) in cats. DESIGN Prospective randomized trial. ANIMALS 66 privately owned cats enrolled between May and December 2010. PROCEDURES BCS and MCS of cats were assessed by 2 investigators; SAP was measured via Doppler ultrasonic flow detector, with cats positioned in right lateral or sternal recumbency for measurements at the radial or coccygeal artery, respectively, with order of site randomized. Associations among variables were assessed through correlation coefficients, partial correlation coefficients, and ANCOVA. RESULTS Interrater reliability for BCS and MCS assessment was high (correlation coefficients, 0.95 and 0.83, respectively). No significant effect was identified for order of SAP measurement sites. Coccygeal and radial SAP were positively correlated (ρ = 0.45). The median difference in coccygeal versus radial SAP was 19 mm Hg, but differences were not consistently positive or negative. Radial SAP was positively correlated with age (ρ = 0.48) and negatively correlated with MCS (ρ = -0.30). On the basis of the correlation analysis, the association between radial SAP and MCS reflected the confounding influence of age. Coccygeal SAP was not significantly correlated with age, BCS, or MCS. CONCLUSIONS AND CLINICAL RELEVANCE Use of the coccygeal artery is recommended to reduce the confounding effects of age and sarcopenia on Doppler ultrasonographic SAP measurements in cats. Additionally, monitoring for changes in MCS is recommended for cats undergoing serial SAP measurement.

  4. Carotid stenosis measurement on colour Doppler ultrasound: Agreement of ECST, NASCET and CCA methods applied to ultrasound with intra-arterial angiographic stenosis measurement

    Energy Technology Data Exchange (ETDEWEB)

    Wardlaw, Joanna M. [Division of Clinical Neurosciences, Western General Hospital, Crewe Road, Edinburgh EH4 2XU (United Kingdom)]. E-mail: jmw@skull.dcn.ed.ac.uk; Lewis, Steff [Division of Clinical Neurosciences, Western General Hospital, Crewe Road, Edinburgh EH4 2XU (United Kingdom)

    2005-11-01

    Purpose: Carotid stenosis is usually determined on Doppler ultrasound from velocity readings. We wondered if angiography-style stenosis measurements applied to ultrasound images improved accuracy over velocity readings alone, and if so, which measure correlated best with angiography. Materials and methods: We studied prospectively patients undergoing colour Doppler ultrasound (CDU) for TIA or minor stroke. Those with 50%+ symptomatic internal carotid artery (ICA) stenosis had intra-arterial angiography (IAA). We measured peak systolic ICA velocity, and from the ultrasound image, the minimal residual lumen, the original lumen (ECST), ICA diameter distal (NASCET) and CCA diameter proximal (CCA method) to the stenosis. The IAAs were measured by ECST, NASCET and CCA methods also, blind to CDU. Results: Amongst 164 patients (328 arteries), on CDU the ECST, NASCET and CCA stenosis measures were similarly related to each other (ECST = 0.54 NASCET + 46) as on IAA (ECST = 0.6 NASCET + 40). Agreement between CDU- and IAA-measured stenosis was similar for ECST (r = 0.51), and CCA (r = 0.48) methods, and slightly worse for NASCET (r = 0.41). Adding IAA-style stenosis to the peak systolic ICA velocity did not improve agreement with IAA over peak systolic velocity alone. Conclusion: Angiography-style stenosis measures have similar inter-relationships when applied to CDU, but do not improve accuracy of ultrasound over peak systolic ICA velocity alone.

  5. Histological analysis of cobalt-chromium stents with and without Camouflage® polymer coating: experimental porcine carotid artery model.

    Science.gov (United States)

    Grudtner, Marco Aurélio; de Lara Elesbão, Joao Luiz; Gutierrez, Paulo Sérgio; Meyer, Fabíola Schons; Pereira, Adamastor Humberto

    2011-04-01

    This study evaluated the arterial response to cobalt-chromium stents with and without polymer coating (Camouflage®, Hemoteq AG, Wuerselen, Germany) implanted in pigs. Cobalt-chromium balloon-expandable stents (4 × 16 mm) were implanted in the common carotid arteries of nine pigs. Histological analysis of endothelialization, inflammation and injury was performed one month later. All stents were successfully deployed, and all but one animal survived the 30 study days. All arteries were patent. Endothelialization was nearly complete in most sections of all carotid stents in both groups. There were mild inflammatory infiltrate and mild-to-moderate injury, which were associated with the stent shafts and not significantly different between groups. Our findings suggest that, in porcine carotid arteries, the histological response to balloon-expandable cobalt-chromium stents coated with polymer (Camouflage®, Hemoteq AG) is similar to the response to non-coated cobalt-chromium stents.

  6. Erythropoietin Attenuates Pulmonary Vascular Remodeling in Experimental Pulmonary Arterial Hypertension through Interplay between Endothelial Progenitor Cells and Heme Oxygenase

    NARCIS (Netherlands)

    van Loon, Rosa Laura E; Bartelds, Beatrijs; Wagener, Frank A D T G; Affara, Nada; Mohaupt, Saffloer; Wijnberg, Hans; Pennings, Sebastiaan W C; Takens, Janny; Berger, Rolf M F

    2015-01-01

    BACKGROUND: Pulmonary arterial hypertension (PAH) is a pulmonary vascular disease with a high mortality, characterized by typical angio-proliferative lesions. Erythropoietin (EPO) attenuates pulmonary vascular remodeling in PAH. We postulated that EPO acts through mobilization of endothelial

  7. Change in Elasticity Caused by Flow-Mediated Dilation Measured Only for Intima-Media Region of Brachial Artery

    Science.gov (United States)

    Sugimoto, Masataka; Hasegawa, Hideyuki; Kanai, Hiroshi

    2005-08-01

    Endothelial dysfunction is considered to be an initial step of arteriosclerosis [R. Ross: N. Engl. J. Med. 340 (2004) 115]. For the assessment of the endothelium function, brachial artery flow-mediated dilation (FMD) caused by increased blood flow has been evaluated with ultrasonic diagnostic equipment. In the case of conventional methods, the change in artery diameter caused by FMD is measured [M. Hashimoto et al.: Circulation 92 (1995) 3431]. Although the arterial wall has a layered structure (intima, media, and adventitia), such a structure is not taken into account in conventional methods because the change in diameter depends on the characteristic of the entire wall. However, smooth muscle present only in the media contributes to FMD, whereas the collagen-rich hard adventitia does not contribute. In this study, we measure the change in elasticity of only the intima-media region including smooth muscle using the phased tracking method [H. Kanai et al.: IEEE Trans. Ultrason. Ferroelectr. Freq. Control 43 (1996) 791]. From the change in elasticity, FMD measured only for the intima-media region by our proposed method was found to be more sensitive than that measured for the entire wall by the conventional method.

  8. Dual-energy CT based vascular iodine analysis improves sensitivity for peripheral pulmonary artery thrombus detection: An experimental study in canines

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chun Xiang [Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing, Jiangsu 210002 (China); Zhang, Long Jiang, E-mail: kevinzhlj@163.com [Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing, Jiangsu 210002 (China); Han, Zong Hong; Zhou, Chang Sheng [Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing, Jiangsu 210002 (China); Krazinski, Aleksander W.; Silverman, Justin R. [Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Schoepf, U. Joseph [Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing, Jiangsu 210002 (China); Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Lu, Guang Ming, E-mail: cjr.luguangming@vip.163.com [Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing, Jiangsu 210002 (China)

    2013-12-01

    Purpose: To evaluate the performance of dual-energy CT (DECT) based vascular iodine analysis for the detection of acute peripheral pulmonary thrombus (PE) in a canine model with histopathological findings as the reference standard. Materials and methods: The study protocol was approved by our institutional animal committee. Thrombi (n = 12) or saline (n = 4) were intravenously injected via right femoral vein in sixteen dogs, respectively. CT pulmonary angiography (CTPA) in DECT mode was performed and conventional CTPA images and DECT based vascular iodine studies using Lung Vessels application were reconstructed. Two radiologists visually evaluated the number and location of PEs using conventional CTPA and DECT series on a per-animal and a per-clot basis. Detailed histopathological examination of lung specimens and catheter angiography served as reference standard. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of DECT and CTPA were calculated on a segmental and subsegmental or more distal pulmonary artery basis. Weighted κ values were computed to evaluate inter-modality and inter-reader agreement. Results: Thirteen dogs were enrolled for final image analysis (experimental group = 9, control group = 4). Histopathological results revealed 237 emboli in 45 lung lobes in 9 experimental dogs, 11 emboli in segmental pulmonary arteries, 49 in subsegmental pulmonary arteries, 177 in fifth-order or more distal pulmonary arteries. Overall sensitivity, specificity, accuracy, PPV, and NPV for CTPA plus DECT were 93.1%, 76.9%, 87.8%, 89.4%, and 84.2% for the detection of pulmonary emboli. With CTPA versus DECT, sensitivities, specificities, accuracies, PPVs, and NPVs are all 100% for the detection of pulmonary emboli on a segmental pulmonary artery basis, 88.9%, 100%, 96.0%, 100%, and 94.1% for CTPA and 90.4%, 93.0%, 92.0%, 88.7%, and 94.1% for DECT on a subsegmental pulmonary artery basis; 23.8%, 96.4%, 50.4%, 93

  9. JUSTIFICATION OF MEASURES TO IMPROVE QUALITY AND ROAD SAFETY AT REGIONAL ARTERIAL STREET IN MINSK

    Directory of Open Access Journals (Sweden)

    V. N. Kuzmenko

    2017-01-01

    Full Text Available The paper presents results pertaining to investigations of traffic conditions and intensity of traffic and pedestrian flows, calculations on loading level of objects located in the Makayonka Street, Minsk. The objects constitute transport regional development which presupposes reconstruction of regional arterial street with due account of infrastructure improvement,   residential  construction and  construction  of  multi-purpose  complex  with   shopping,  entertainment,   wellness  and business centers. In addition to this it is planned to construct a two-level underground parking, a two-level interchange at intersection of the Filimonova Street and Nezavisimosty Avenue due to an increase of traffic load at adjacent neighboring street and road network. An analysis on the current traffic management and calculation for distribution of the existing and prospective traffic load levels after implementation of appropriate measures to improve quality as a whole and road safety as well has been carried out in the paper. Determination of loading levels for a street and road network has been carried out while taking into account an intensity of traffic flows in order to evaluate various options for road traffic organization. Variants for planning of road junctions, road traffic organization and traffic signalization (including coordinated passing of  transport facilities have been developed in the paper. All this will contribute to improvement of quality and road safety in the investigated street with due consideration of further development of the region and overbuilding of the existing housing system in the Makayonka Streets and increase of its transport importance in the Minsk street and road network.

  10. Effects of diagnostic guidewire catheter presence on translesional hemodynamic measurements across significant coronary artery stenoses.

    Science.gov (United States)

    Banerjee, Rupak K; Back, Lloyd H; Back, Martin R

    2003-01-01

    This study gains insight on the nature of flow blockage effects of small guidewire catheter sensors in measuring mean trans-stenotic pressure gradients Deltap across significant coronary artery stenoses. Detailed pulsatile hemodynamic computations were made in conjunction with previously reported clinical data in a group of patients with clinically significant coronary lesions before angioplasty. Results of this study ascertain changes in hemodynamic conditions due to the insertion of a guidewire catheter (di=0.46 mm) across the lesions used to directly determine the mean pressure gradient (Deltap) and fall in distal mean coronary pressure (pr). For the 32 patient group of Wilson et al. [1988] (minimal lesion diameter dm=0.95 mm; 90% mean area stenosis; proximal measured coronary flow reserve (CFR) of 2.3 in the abnormal range) the diameter ratio of guidewire catheter to minimal lesion was 0.48, causing a tighter "artifactual" mean area stenosis of 92.1%. The results of the computations indicated a significant shift in the Deltap-Q relation due to guidewire induced increases in flow resistances (R=Deltap/Q) of 110% for hyperemic flow, a 35% blockage in hyperemic flow (Qh) and a phase shift of the coronary flow waveform to systolic predominance. These alterations in flow resulted in a fall in distal mean coronary pressure (at lower mean flow rates) below the patho-physiological range of prh approximately 55 mmHg, which is known to cause ischemia in the subendocardium (Brown et al. [1984]) and coincides with symptomatic angina. Transient wall shear stress levels in the narrow throat region (with flow blockage) were of the order of levels during hyperemic conditions for patho-physiological flow. In the separated flow region along the distal vessel wall, vortical flow cells formed periodically during the systolic phase when instantaneous Reynolds numbers Ree(t) exceeded about 110. For patho-physiological flow without the presence of the guidewire these vortical flow

  11. Echocardiographic measurements in normal chinese adults focusing on cardiac chambers and great arteries: a prospective, nationwide, and multicenter study.

    Science.gov (United States)

    Yao, Gui-Hua; Deng, Yan; Liu, Yan; Xu, Ming-Jun; Zhang, Cheng; Deng, You-Bin; Ren, Wei-Dong; Li, Zhi-An; Tang, Hong; Zhang, Quan-Bin; Mu, Yu-Ming; Fang, Li-Gang; Zhang, Mei; Yin, Li-Xue; Zhang, Yun

    2015-05-01

    Currently available echocardiographic reference values are derived mainly from North American and European population studies, and no echocardiographic reference values are available for the Chinese population. The aim of this study was to establish normal values of echocardiographic measurements of the cardiac chambers and great arteries in a nationwide, population-based cohort of healthy Han Chinese adults. A total of 1,586 healthy Han Chinese volunteers aged 18 to 79 years were screened at 43 collaborating laboratories throughout China. Standard M-mode and two-dimensional echocardiography was performed to obtain measurements of the cardiac chambers and great arteries. The impacts of gender and age on all echocardiographic measurements were analyzed. A total of 1,394 qualified healthy subjects (mean age, 47.3 ± 16.0 years; 678 men) were ultimately enrolled. Except for left ventricular ejection fraction, values of cardiac chamber and great arterial dimensions were significantly higher in men than in women. Most measurements of the atrial and great arterial dimensions, left ventricular wall thickness, and left ventricular mass increased with age in both men and women. Normal reference values of cardiac dimensional parameters were established for the first time in a nationwide, population-based cohort of healthy Han Chinese adults. Because most of these parameters were found to vary with gender and age, reference values stratified for gender and age should be used in clinical practice. Copyright © 2015 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

  12. Transcutaneous PTCCO2 measurement in combination with arterial blood gas analysis provides superior accuracy and reliability in ICU patients.

    Science.gov (United States)

    Spelten, Oliver; Fiedler, Fritz; Schier, Robert; Wetsch, Wolfgang A; Hinkelbein, Jochen

    2017-02-01

    Hyper or hypoventilation may have serious clinical consequences in critically ill patients and should be generally avoided, especially in neurosurgical patients. Therefore, monitoring of carbon dioxide partial pressure by intermittent arterial blood gas analysis (PaCO2) has become standard in intensive care units (ICUs). However, several additional methods are available to determine PCO2 including end-tidal (PETCO2) and transcutaneous (PTCCO2) measurements. The aim of this study was to compare the accuracy and reliability of different methods to determine PCO2 in mechanically ventilated patients on ICU. After approval of the local ethics committee PCO2 was determined in n = 32 ICU consecutive patients requiring mechanical ventilation: (1) arterial PaCO2 blood gas analysis with Radiometer ABL 625 (ABL; gold standard), (2) arterial PaCO2 analysis with Immediate Response Mobile Analyzer (IRMA), (3) end-tidal PETCO2 by a Propaq 106 EL monitor and (4) transcutaneous PTCCO2 determination by a Tina TCM4. Bland-Altman method was used for statistical analysis; p analysis revealed good correlation between PaCO2 by IRMA and ABL (R2 = 0.766; p analysis revealed a bias and precision of 2.0 ± 3.7 mmHg for the IRMA, 2.2 ± 5.7 mmHg for transcutaneous, and -5.5 ± 5.6 mmHg for end-tidal measurement. Arterial CO2 partial pressure by IRMA (PaCO2) and PTCCO2 provided greater accuracy compared to the reference measurement (ABL) than the end-tidal CO2 measurements in critically ill in mechanically ventilated patients patients.

  13. Comparison of non-invasive and invasive arterial blood pressure measurement for assessment of dynamic cerebral autoregulation.

    Science.gov (United States)

    Petersen, Nils H; Ortega-Gutierrez, Santiago; Reccius, Andres; Masurkar, Arjun; Huang, Amy; Marshall, Randolph S

    2014-02-01

    There is a growing interest in measuring cerebral autoregulation in patients with acute brain injury. Non-invasive finger photo-plethysmography (Finapres) is the method of choice to relate arterial blood pressure to changes in cerebral blood flow. Among acutely ill patients, however, peripheral vasoconstriction often limits the use of Finapres requiring direct intravascular blood pressure measurement. We evaluated how these two different forms of blood pressure monitoring affect the parameters of dynamic cerebral autoregulation (DCA). We performed 37 simultaneous recordings of BP and cerebral blood flow velocity in 15 patients with acute brain injury. DCA was estimated in the frequency domain using transfer function analysis to calculate phase shift, gain, and coherence. In addition the mean velocity index (Mx) was calculated for assessment of DCA in the time domain. The mean patient age was 58.1 ± 15.9 years, 80 % (n = 12) were women. We found good inter-method agreement between Finapres and direct intravascular measurement using Bland–Altman and correlation analyses. Finapres gives higher values for the efficiency of dynamic CA compared with values derived from radial artery catheter, as indicated by biases in the phase (26.3 ± 11.6° vs. 21.7 ± 10.5°, p = 0.001) and Mx (0.571 ± 0.137 vs. 0.649 ± 0.128, p blood pressure methods. The average coherence between CBFV and ABP was higher when BP was measured with arterial catheter for frequencies above 0.05 Hz (0.8 vs. 0.73, p invasive arterial blood pressure monitoring may improve accuracy and thus should be the preferred method for DCA assessment in the ICU.

  14. Arterial stiffness

    Directory of Open Access Journals (Sweden)

    Ursula Quinn

    2012-09-01

    Full Text Available Measurements of biomechanical properties of arteries have become an important surrogate outcome used in epidemiological and interventional cardiovascular research. Structural and functional differences of vessels in the arterial tree result in a dampening of pulsatility and smoothing of blood flow as it progresses to capillary level. A loss of arterial elastic properties results a range of linked pathophysiological changes within the circulation including increased pulse pressure, left ventricular hypertrophy, subendocardial ischaemia, vessel endothelial dysfunction and cardiac fibrosis. With increased arterial stiffness, the microvasculature of brain and kidneys are exposed to wider pressure fluctuations and may lead to increased risk of stroke and renal failure. Stiffening of the aorta, as measured by the gold-standard technique of aortic Pulse Wave Velocity (aPWV, is independently associated with adverse cardiovascular outcomes across many different patient groups and in the general population. Therefore, use of aPWV has been proposed for early detection of vascular damage and individual cardiovascular risk evaluation and it seems certain that measurement of arterial stiffness will become increasingly important in future clinical care. In this review we will consider some of the pathophysiological processes that result from arterial stiffening, how it is measured and factors that may drive it as well as potential avenues for therapy. In the face of an ageing population where mortality from atheromatous cardiovascular disease is falling, pathology associated with arterial stiffening will assume ever greater importance. Therefore, understanding these concepts for all clinicians involved in care of patients with cardiovascular disease will become vital.

  15. Agreement of high definition oscillometry with direct arterial blood pressure measurement at different blood pressure ranges in horses under general anaesthesia.

    Science.gov (United States)

    Tünsmeyer, Julia; Hopster, Klaus; Feige, Karsten; Kästner, Sabine Br

    2015-05-01

    To determine the agreement of high definition oscillometry (HDO) with direct arterial blood pressure measurements in normotensive, hypotensive and hypertensive horses during general anaesthesia. Experimental study. Seven healthy warmblood horses, aged 3-11 years, weighing 470-565 kg. Measurements from a HDO device with the cuff placed around the base of the tail were compared with pressures measured invasively from the facial artery. High blood pressures were induced by intravenous (IV) administration of dobutamine (5 μg kg(-1) minute(-1)) over ten minutes followed by norepinephrine (0.1 mg kg(-1) IV) and low pressures by increasing the inspired fraction of isoflurane and administration of nitroglycerine (0.05 mg kg(-1) IV). For analysis three pressure levels were determined: high (MAP>110 mmHg), normal (60 mmHginvasive and invasive measurements. A total of 245 paired measurements of systolic (SAP), mean (MAP) and diastolic (DAP) pressures were obtained. The HDO device underestimated blood pressure at hypertensive and normotensive levels and overestimated blood pressure at hypotensive levels. Best agreement was obtained for SAP and MAP within normotensive limits. At normotension, bias ± standard deviation for SAP, MAP and DAP were 0.1 ± 19.4 mmHg, 0.5 ± 14.0, 4.7 ± 15.6, respectively. At high pressure levels bias and SD were 26.1 ± 37.3 (SAP), 4.2 ± 19.4 (MAP), 1.5 ± 16.8 (DAP) and at low pressures -20.0 ± 20.9 (SAP), -11.4 ± 19.6 (MAP), -4.7 ± 20.1 (DAP), with HDO measurements at a MAP invasive arterial blood pressures was obtained with HDO at normotensive levels in horses. At high and low pressure ranges HDO was unreliable. Therefore, if haemodynamic instability is expected, invasive measurement remains preferable. © 2014 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

  16. Variabilities in measurement of coronary arterial dimensions resulting from variations in cineframe selection

    NARCIS (Netherlands)

    J.H.C. Reiber (Johan); P. van Eldik-Helleman; N. Visser-Akkerman; C.J. Kooijman; P.W.J.C. Serruys (Patrick)

    1988-01-01

    textabstractTo quantitatively analyze a coronary arterial segment from a cineangiogram, an end-diastolic or neighboring cineframe is usually selected, such that a possibly existing coronary lesion is visualized optimally, as judged by the cardiologist. However, different cardiologists may select

  17. Physical Activity in Pediatric Pulmonary Arterial Hypertension Measured by Accelerometry : A Candidate Clinical Endpoint

    NARCIS (Netherlands)

    Zijlstra, Willemijn M H; Ploegstra, Mark-Jan; Vissia-Kazemier, Theresia R; Roofthooft, Marcus T. R.; du Marchie Sarvaas, Gideon; Bartelds, Beatrijs; Rackowitz, Annette; van den Heuvel, Freek; Hillege, Hans L; Plasqui, Guy; Berger, Rolf M F

    2017-01-01

    Rationale: The development of evidence-based treatment guidelines for pediatric pulmonary arterial hypertension (PAH) is hampered by lack of pediatric clinical trials. Trial design is hampered by lack of a feasible clinical endpoint in this population. Objectives: To evaluate the use of

  18. Experimental techniques for mass measurement far from stability

    Energy Technology Data Exchange (ETDEWEB)

    Orr, N

    2001-01-01

    The measurement of nuclear masses is a fundamental tool to probe nuclear structure ar from stability. A review of the techniques that have been most commonly employed to undertake such measurements is presented. (author)

  19. Assessment of the arterial stiffness in patients with acute ischemic stroke using longitudinal elasticity modulus measurements obtained with Shear Wave Elastography.

    Science.gov (United States)

    Li, Zhaojun; Du, Lianfang; Wang, Feng; Luo, Xianghong

    2016-06-01

    Arterial wall elasticity including the circumferential and longitudinal modulus is a measure of sub-clinical cardiovascular disease; the circumferential modulus is increased in acute ischemic stroke (AIS). There are still no reports of non-invasive measurement of longitudinal elastic modulus of arterial wall and its prospect of clinical application. In this study, the longitudinal elastic modulus of the arterial wall was assessed using real-time shear wave elastography in patients with AIS. The technique's feasibility and its related factors were studied initially. In this study 179 patients with AIS and 168 age- and sex-matched controls were examined. The pulse wave velocity (PWV) of the bilateral carotid arteries was measured using radio frequency ultrasound technology. The 20 areas of superficial walls of bilateral carotid artery were analyzed by real-time shear wave elastography (SWE), and the average values of longitudinal average elastic modulus (ME-mean), maximum elastic modulus (ME-max), minimum elastic modulus (ME-min), and elastic modulus standard deviation (MESD) were measured. The PWV, ME-mean, ME-max and ME-sp of the carotid artery in patients with AIS were greater than those in the control group. Age, systolic blood pressure, PWV, and low-density lipoprotein were positively related to ME-mean and ME-max (r=0.221and r=0.248, r=0.174 and r=0.176, r=0.776 and r=0.716, r=0.173 and r=0.200, pelastic modulus of the arterial wall and evaluate the arterial stiffness. It was equivalent to the PWV which showed circular elastic modulus of arterial wall on evaluating AIS. Age, systolic blood pressure, pulse wave velocity, and low-density lipoprotein were independent risk factors for longitudinal elastic modulus. SWE may be effective in the assessment of arterial stiffness and offer a potential clinical benefit.

  20. Measurement of the ultrasonic properties of human coronary arteries in vitro with a 50-MHz acoustic microscope

    Directory of Open Access Journals (Sweden)

    Machado J.C.

    2002-01-01

    Full Text Available Ultrasonic attenuation coefficient, wave propagation speed and integrated backscatter coefficient (IBC of human coronary arteries were measured in vitro over the -6 dB frequency bandwidth (36 to 67 MHz of a focused ultrasound transducer (50 MHz, focal distance 5.7 mm, f/number 1.7. Corrections were made for diffraction effects. Normal and diseased coronary artery sub-samples (N = 38 were obtained from 10 individuals at autopsy. The measured mean ± SD of the wave speed (average over the entire vessel wall thickness was 1581.04 ± 53.88 m/s. At 50 MHz, the average attenuation coefficient was 4.99 ± 1.33 dB/mm with a frequency dependence term of 1.55 ± 0.18 determined over the 36- to 67-MHz frequency range. The IBC values were: 17.42 ± 13.02 (sr.m-1 for thickened intima, 11.35 ± 6.54 (sr.m-1 for fibrotic intima, 39.93 ± 50.95 (sr.m-1 for plaque, 4.26 ± 2.34 (sr.m-1 for foam cells, 5.12 ± 5.85 (sr.m-1 for media and 21.26 ± 31.77 (sr.m-1 for adventitia layers. The IBC results indicate the possibility for ultrasound characterization of human coronary artery wall tissue layer, including the situations of diseased arteries with the presence of thickened intima, fibrotic intima and plaque. The mean IBC normalized with respect to the mean IBC of the media layer seems promising for use as a parameter to differentiate a plaque or a thickened intima from a fibrotic intima.

  1. 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.

  2. Evaluation of the oscillometric technique for intermittent non-invasive arterial blood pressure measurement in the anaesthetized pig.

    Science.gov (United States)

    Ypsilantis, P; Didilis, V; Simopoulos, C

    2013-04-01

    This study was designed to evaluate the oscillometric technique for intermittent non-invasive measurement of arterial pressure (AP) in the anaesthetized pig. In six pigs under sevoflurane anaesthesia, intermittent (every 2 minutes) oscillometric measurements of AP made at a forelimb (FL), a hindlimb (HL) and the tail base were compared with simultaneous direct AP measurements made at the aortic arch (AA) over a wide pressure range (30-140 mmHg of mean AP). All oscillometric measurements strongly correlated (Pearson correlation coefficient >0.837, P oscillometric and AA pressure readings at graded pressure levels, measurements made at the tail base provided reliable prediction of systolic AP, at the FL of diastolic AP and at both the tail base and the FL of mean AP. In conclusion, oscillometric measurements at the FL and the tail base offer reliable prediction of AP in the anaesthetized pig.

  3. [Effects of the overlapping between an experimental model of neuroendocrine obesity with arterial hypertension under blood pressure, body weight and metabolic and renal parameters in rats].

    Science.gov (United States)

    Ferreira, Lara Beatriz Delfino; Cesaretti, Mario Luis Ribeiro; Voltera, Aline Francisco; Ginoza, Milton; Kohlmann, Osvaldo

    2011-01-01

    Increased body mass index and the metabolic syndrome are associated with decreased renal function and the development of end-stage kidney disease. To evaluate the effect of the overlap between an experimental model of obesity and genetic hypertension on the blood pressure, body weight and metabolic and kidney parameters of rats. We studied male rats of the Wistar (WST) and spontaneously hypertensive rats (SHR) strains. Monosodium glutamate (MSG) was administered in the neonatal period to both strains, to make up two groups: WST + MSG and SHR + MSG. Animals in the control groups (WST and SHR) received saline. After completing three months of life, a 12-week follow-up period ensued, during which bi-weekly measurements of body weight (BW) and tail-cuff blood pressure (TCBP) were obtained. Microalbuminuria was analyzed at weeks 0, 4, 8 and 12. At the end of the follow-up period, blood was obtained for fasting glucose, plasma creatinine, and lipid profile determinations. The kidneys were removed, stained, and the glomerular sclerosis index was calculated. The administration of MSG produced higher percentage body weight gain, higher fasting blood glucose and a higher degree of glomerular injury in WST-MSG and MSG-SHR rats, compared to their controls. Greater urinary albumin excretion was observed in SHR + MSG rats, when compared to SHR. There was no statistical difference in the TCBP, creatinine, and lipid profile. The association of neuroendocrine obesity and arterial hypertension promoted morphological and functional changes in the glomerulus. These changes were more severe than those observed in hypertensive-only rats.

  4. Accuracy of Parenchymal Cerebral Blood Flow Measurements Using Pseudocontinuous Arterial Spin-Labeling in Healthy Volunteers.

    Science.gov (United States)

    Ambarki, K; Wåhlin, A; Zarrinkoob, L; Wirestam, R; Petr, J; Malm, J; Eklund, A

    2015-10-01

    The arterial spin-labeling method for CBF assessment is widely available, but its accuracy is not fully established. We investigated the accuracy of a whole-brain arterial spin-labeling technique for assessing the mean parenchymal CBF and the effect of aging in healthy volunteers. Phase-contrast MR imaging was used as the reference method. Ninety-two healthy volunteers were included: 49 young (age range, 20-30 years) and 43 elderly (age range, 65-80 years). Arterial spin-labeling parenchymal CBF values were averaged over the whole brain to quantify the mean pCBF(ASL) value. Total CBF was assessed with phase-contrast MR imaging as the sum of flows in the internal carotid and vertebral arteries, and subsequent division by brain volume returned the pCBF(PCMRI) value. Accuracy was considered as good as that of the reference method if the systematic difference was less than 5 mL/min/100 g of brain tissue and if the 95% confidence intervals were equal to or better than ±10 mL/min/100 g. pCBF(ASL) correlated to pCBF(PCMRI) (r = 0.73; P volunteers. The systematic differences (mean ± 2 standard deviations) were -4 ± 14 mL/min/100 g in the young subjects and 6 ± 12 mL/min/100 g in the elderly subjects. Young subjects showed higher values than the elderly subjects for pCBF(PCMRI) (young, 57 ± 8 mL/min/100 g; elderly, 54 ± 7 mL/min/100 g; P = .05) and pCBF(ASL) (young, 61 ± 10 mL/min/100 g; elderly, 48 ± 10 mL/min/100 g; P < .001). The limits of agreement were too wide for the arterial spin-labeling method to be considered satisfactorily accurate, whereas the systematic overestimation in the young subjects and underestimation in the elderly subjects were close to acceptable. The age-related decrease in parenchymal CBF was augmented in arterial spin-labeling compared with phase-contrast MR imaging. © 2015 by American Journal of Neuroradiology.

  5. Mechanical instability of normal and aneurysmal arteries.

    Science.gov (United States)

    Lee, Avione Y; Sanyal, Arnav; Xiao, Yangming; Shadfan, Ramsey; Han, Hai-Chao

    2014-12-18

    Tortuous arteries associated with aneurysms have been observed in aged patients with atherosclerosis and hypertension. However, the underlying mechanism is poorly understood. The objective of this study was to determine the effect of aneurysms on arterial buckling instability and the effect of buckling on aneurysm wall stress. We investigated the mechanical buckling and post-buckling behavior of normal and aneurysmal carotid arteries and aorta's using computational simulations and experimental measurements to elucidate the interrelationship between artery buckling and aneurysms. Buckling tests were done in porcine carotid arteries with small aneurysms created using elastase treatment. Parametric studies were done for model aneurysms with orthotropic nonlinear elastic walls using finite element simulations. Our results demonstrated that arteries buckled at a critical buckling pressure and the post-buckling deflection increased nonlinearly with increasing pressure. The presence of an aneurysm can reduce the critical buckling pressure of arteries, although the effect depends on the aneurysm's dimensions. Buckled aneurysms demonstrated a higher peak wall stress compared to unbuckled aneurysms under the same lumen pressure. We conclude that aneurysmal arteries are vulnerable to mechanical buckling and mechanical buckling could lead to high stresses in the aneurysm wall. Buckling could be a possible mechanism for the development of tortuous aneurysmal arteries such as in the Loeys-Dietz syndrome. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Optimizing the imaging protocol for vivo coronary artery wall using high-resolution MIRI: An experimental study on porcine and human

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jiang; Li, Tao; Cul, Xiaoming; Zhou, Weihua; Zhang, Xinwu [The General Hospital of Chinese People' s Armed Police Forces, Beijing (China)

    2013-08-15

    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.

  7. Nonlinear Optical Measurements of the Artery Wall: Parameters Related to the Progression of Atherosclerosis

    Science.gov (United States)

    Sowa, Michael G.; Mostaco-Guidolin, Leila B.; Smith, Michael S. D.; Kohlenberg, Elica K.; Ridsdale, Andrew; Stolow, Albert; Ko, Alex C. T.

    2009-01-01

    Nonlinear optical (NLO) microscopy is used to follow key structural and biochemical changes associated with the progression of atherosclerosis. Arteries from WHHL-MI rabbits are examined using a 3 channel NLO microscope that can simultaneously monitor the coherent anti-stokes Raman scattered light (CARS), the two-photon excited fluorescence (TPEF) and the second harmonic generation (SHG) from a sample. Distinct differences in the nonlinear optical signals are observed that correlate with the age of the vessel and the presence of atherosclerotic plaque. These differences are attributed to the changing extracellular matrix and the increased lipid deposition associated with plaque development. The capability of NLO to perform 3D sectioning in thick highly scattering vessels in order to visualize structural details of the artery wall and highlight vessel pathology is demonstrated. These features make NLO a potentially valuable tool to help understand the progression of atherosclerosis.

  8. Operational measure of entanglement based on experimental consequences.

    Energy Technology Data Exchange (ETDEWEB)

    Grondalski, J. P. (John P.); James, D. F. (Daniel F.)

    2002-01-01

    The maximum eigenvalue of the real part of the density matrix expressed in a maximally entangled basis with a particular phase relationship can be used as an operational measure of entanglement. This measure is related to the fidelity, maximized with a local unitary operating on either subsystem, of a standard dense coding, teleportation, or entanglement swapping protocol.

  9. Measurement of pleural pressure swings with a fluid-filled esophageal catheter vs pulmonary artery occlusion pressure.

    Science.gov (United States)

    Verscheure, S; Massion, P B; Gottfried, S; Goldberg, P; Samy, L; Damas, P; Magder, S

    2017-02-01

    Pleural pressure measured with esophageal balloon catheters (Peso) can guide ventilator management and help with the interpretation of hemodynamic measurements, but these catheters are not readily available or easy to use. We tested the utility of an inexpensive, fluid-filled esophageal catheter (Peso) by comparing respiratory-induced changes in pulmonary artery occlusion (Ppao), central venous (CVP), and Peso pressures. We studied 30 patients undergoing elective cardiac surgery who had pulmonary artery and esophageal catheters in place. Proper placement was confirmed by chest compression with airway occlusion. Measurements were made during pressure-regulated volume control (VC) and pressure support (PS) ventilation. The fluid-filled esophageal catheter provided a high-quality signal. During VC and PS, change in Ppao (∆Ppao) was greater than ∆Peso (bias = -2 mm Hg) indicating an inspiratory increase in cardiac filling. During VC, ∆CVP bias was 0 indicating no change in right heart filling, but during PS, CVP fell less than Peso indicating an inspiratory increase in filling. Peso measurements detected activation of expiratory muscles, development of non-west zone 3 lung conditions during inspiration, and ventilator-triggered inspiratory efforts. A fluid-filled esophageal catheter provides a high-quality, easily accessible, and inexpensive measure of change in pleural pressure and provided insights into patient-ventilator interactions. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. A cell culture model using rat coronary artery adventitial fibroblasts to measure collagen production

    OpenAIRE

    Meszaros Gary; Doane Kathleen; Milsted Amy; Jenkins Cathleen; Toot Jonathan; Ely Daniel

    2007-01-01

    Abstract Background We have developed a rat cell model for studying collagen type I production in coronary artery adventitial fibroblasts. Increased deposition of adventitial collagen type I leads to stiffening of the blood vessel, increased blood pressure, arteriosclerosis and coronary heart disease. Although the source and mechanism of collagen deposition is yet unknown, the adventitia appears to play a significant role. To demonstrate the application of our cell model, cultured adventitial...

  11. The Sonographic Stenosis Index: A New Specific Quantitative Measure of Transplant Hepatic Arterial Stenosis.

    Science.gov (United States)

    Le, Thomas X; Hippe, Daniel S; McNeeley, Michael F; Dighe, Manjiri K; Dubinsky, Theodore J; Chan, Sherwin S

    2017-04-01

    This study evaluates the sensitivity and specificity of stenosis index (SI), which accounts for the entire spectral Doppler waveform, to detect significant transplant hepatic arterial stenosis. In this institutional review board-approved, HIPAA compliant study, we retrospectively analyzed 69 patients who had catheter angiography for suspected transplant hepatic arterial stenosis (THAS) between January 2006 and December 2010; all patients had Doppler ultrasound within 30 days before angiography. Patients with angiographic stenosis requiring intervention were considered positive for THAS. Stenosis index was calculated from each patient's spectral Doppler ultrasound images by obtaining the ratio of the area under the high-frequency signal to low-frequency signal in the spectral Doppler. Resistive index (RI) and pulsatility index (PI) were also calculated. Receiver operator curve analysis was performed and the area under the curve (AUC) was compared among the three metrics. Forty-eight of 69 patients had THAS by angiography requiring intervention; 21patients had no angiographic evidence of THAS. SI was significantly different (P transplant hepatic artery stenosis. © 2016 by the American Institute of Ultrasound in Medicine.

  12. Phylloquinone (vitamin K₁) intake and pulse pressure as a measure of arterial stiffness in older adults.

    Science.gov (United States)

    Vaccaro, Joan A; Huffman, Fatma G

    2013-01-01

    This study examined the relationships among ethnicity/race, lifestyle factors, phylloquinone (vitamin K₁) intake, and arterial pulse pressure in a nationally representative sample of older adults from four ethnic/racial groups: non-Hispanic Whites, non-Hispanic Blacks, Mexican Americans, and other Hispanics. This was a cross-sectional study of U.S. representative sample with data from the National Health and Nutrition Examination Surveys, 2007-2008 and 2009-2010 of adults aged 50 years and older (N = 5296). Vitamin K intake was determined by 24-hour recall. Pulse pressure was calculated as the difference between the averages of systolic blood pressure and diastolic blood pressure. Compared to White non-Hispanics, the other ethnic/racial groups were more likely to have inadequate vitamin K₁ intake. Inadequate vitamin K₁ intake was an independent predictor of high arterial pulse pressure. This was the first study that compared vitamin K₁ inadequacy with arterial pulse pressure across ethnicities/races in U.S. older adults. These findings suggest that vitamin K screening may be a beneficial marker for the health of older adults.

  13. Quality of life in opium-addicted patients with coronary artery disease as measured with WHOQOL-BREF.

    Science.gov (United States)

    Najafi, Mahdi; Sheikhvatan, Mehrdad; Montazeri, Ali; Sheikhfathollahi, Mahmood

    2009-05-01

    Several factors can influence the quality of life in patients with coronary artery disease (CAD). The goal of this research was to measure quality of life in opium-addicted patients with CAD in order to assess the effect of CAD risk factors on their quality of life. The WHOQOL-BREF questionnaire was completed through interviews with 275 patients who underwent isolated coronary artery bypass surgery in Tehran Heart Centre between May and September 2006. No significant differences were found in the mean scores of the four domains of quality of life between the addicted and non-addicted patients. Furthermore, the evaluation of QOL in the groups with CAD risk factors showed that the mean QOL domains were statistically similar between opium addicted and non-opium addicted patients. In the addicted group, men had a higher psychological health score than women. A previous history of myocardial infarction reduced the psychological score in this group. Also, in the addicted patients with a history of diabetes mellitus, social functioning was better than that of the non-diabetics. The different domains of quality of life in our opium-addicted and non-addicted patients with CAD were similar; and among all the major risk factors for coronary artery disease, only female gender and a previous history of myocardial infarction could influence quality of life in the opium-addicted patients.

  14. Analysis of experimental biosensor/FIA lactose measurements

    Directory of Open Access Journals (Sweden)

    L.S. Ferreira

    2003-03-01

    Full Text Available Whey is an abundant effluent in the production of cheese and casein. The biotechnological utilization of this economically important and nutritive source is limited mainly because of the presence of high percentages of lactose. This disaccharide has poor solubility, which can cause crystallization and insufficient sweetness in dairy food; additionally, part of the adult population suffers from associated lactose intolerance diseases. There are several methods to determine lactose such as spectrophotometry, polarimetry, infrared spectroscopy, titrimetry and chromatography. However these methods are tedious and time-consuming due to long sample preparation. These disadvantages stimulated the development of an enzymatic lactose biosensor. It employs two immobilized enzymes, beta-galactosidase and glucose oxidase and the quantitative analysis of lactose is based on determination of oxygen consumption in the enzymatic reaction. The influence of temperature on the biosensor signal was experimentally studied. It was observed that a nonlinear relationship exists between the electric response of the biosensor - provided by CAFCA (Computer Assisted Flow Control & Analysis - ANASYSCON, Hannover - and lactose concentration. In this work, attempts were made to correlate these variables using a simple nonlinear model and multilayered neural networks, with the latter providing the best modeling of the experimental data.

  15. Performance measurement, expectancy and agency theory: An experimental study

    OpenAIRE

    Sloof, R.; van Praag, C.M.

    2008-01-01

    Theoretical analyses of (optimal) performance measures are typically performed within the realm of the linear agency model. An important implication of this model is that, for a given compensation scheme, the agent's optimal effort choice is unrelated to the amount of noise in the performance measure. In contrast, expectancy theory as developed by psychologists predicts that effort levels are increasing in the signal-to-noise ratio. We conduct a real effort laboratory experiment to assess the...

  16. The Accuracy of the CNAP® Device Compared with Invasive Radial Artery Measurements for Providing Continuous Noninvasive Arterial Blood Pressure Readings at a Medical Intensive Care Unit: A Method-Comparison Study.

    Science.gov (United States)

    Smolle, Karl-Heinz; Schmid, Martin; Prettenthaler, Helga; Weger, Christian

    2015-12-01

    In cases of intensive care unit (ICU) patients without an arterial line, noninvasive continuous blood pressure monitoring could be very beneficial. The CNAP® monitor (CNSystems Medizintechnik AG) provides noninvasive, beat-to-beat blood pressure (BP) estimates using the volume clamp method to measure finger arterial pressure calibrated to brachial pressure values. The aim of this study was to compare noninvasive BP estimates of the CNAP monitor with invasive blood pressure (IBP) measurements obtained via a radial arterial catheter in unselected medical ICU patients under routine clinical conditions. In 40 adult patients, IBP and noninvasive CNAP blood pressure (CBP) were measured simultaneously for 30 minutes. Bland-Altman analysis accounting for repeated measurements revealed accuracy and precision of CBP toward IBP. Percentage errors were calculated using the summary measures method and tested for interchangeability. Trending analysis was assessed using 4-quadrant plots and polar plots, whereby each reported statistical calculation used the sample size of n = 40 patients. A total of 7200 measurement pairs of CBP and IBP were analyzed. For mean arterial pressure, accuracy ± precision resulted in 4.6 ± 6.7 mm Hg (limits of agreement -8.7 to 17.8 mm Hg) with a percentage error of 6.77% (95% confidence interval [CI], 6.57%-6.97%). Trending analysis of 3-minute intervals showed a concordance rate of 94.6% (95% CI, 94.0%-95.2%; exclusion zone 10%) and a polar concordance rate of 99.50% (95% CI, 99.48%-99.52%) for changes lying within 10% limits. The CNAP device provided feasible estimates of BP in unselected medical ICU patients under routine clinical conditions. Mean arterial pressure met interchangeability criteria for accuracy toward radial arterial pressure, as well as for percentage error, and showed good trending capabilities according to the Critchley predefined criteria.

  17. Empleo del parche valvado en el tratamiento de la comunicación interauricular en pacientes con hipertensión arterial pulmonar grave. Estudio cuasi-experimental

    Directory of Open Access Journals (Sweden)

    Horacio Márquez-González

    2015-10-01

    Full Text Available Introducción: La comunicación interauricular detectada en la adultez se acompaña de hipertensión arterial pulmonar. El procedimiento quirúrgico correctivo en estas condiciones presenta mayor morbilidad y mortalidad. El empleo del parche valvado evita la aparición de complicaciones tempranas.Objetivos: Analizar el comportamiento a dos años de la presión pulmonar estimada por ecocardiograma, y la función ventricular derecha en pacientes operados de cierre de comunicación interauricular con hipertensión arterial pulmonar grave con parche valvado.Método: Se realizó un estudio cuasi-experimental en 12 pacientes con comunicación interauricular de malos bordes e hipertensión arterial pulmonar grave. Se incluyeron sujetos con pruebas de reactividad positiva a oxígeno u óxido nítrico, que brindaron su consentimiento informado y se excluyeron enfermos con síndromes genéticos o hipertensión arterial pulmonar primaria. Los pacientes fueron seguidos en el posquirúrgico inmediato clínicamente, por laboratorio y por ecocardiografía a los 2, 4, 6, 12, 18 y 24 meses del posquirúrgico. Se registraron las complicaciones agregadas.Resultados: En los 12 pacientes que fueron analizados no se presentaron defunciones tempranas o tardías, la mediana de ventilación mecánica fue de 2 (1-4 días. En el seguimiento se constató mejoría significativa en: la clase funcional, las variables ecocardiográficas y la utilización de medicamentos.Conclusiones: El parche valvado unidireccional es una opción terapéutica que evita las complicaciones posquirúrgicas responsables de la mortalidad temprana.

  18. Experimental investigations into visual and electronic tooth color measurement.

    Science.gov (United States)

    Ratzmann, Anja; Treichel, Anja; Langforth, Gabriele; Gedrange, Tomasz; Welk, Alexander

    2011-04-01

    The present study aimed to examine the validity of the visual color assessment and an electronic tooth color measurement system by means of Shade Inspector™ in comparison with a gold standard. Additionally, reproducibility of electronic measurements was demonstrated by means of two reference systems. Ceramic specimens of two thicknesses (h=1.6 mm, h=2.6 mm) were used. Three experienced dental technicians using the VITAPAN Classical(®) color scale carried out all visual tests. Validity of the visual assessment and the electronic measurements was confirmed separately for both thicknesses by means of lightness and hue of the VITAPAN Classical(®) color scale. Reproducibility of electronic measurements was confirmed by means of the VITAPAN Classical(®) and 3D-Master(®). The 3D-Master(®) data were calculated according to lightness, hue and chroma. Intraclass correlation coefficient (ICC) was used in assessing validity/reproducibility for lightness and chroma, Kappa statistics were used for hue. A level ≥0.75 was pre-established for ICC and ≥0.60 for the Kappa index. RESULTS OF VISUAL COLOR ASSESSMENT: Validity for lightness was good for both thicknesses; agreement rates for hue were inconsistent. ELECTRONIC MEASUREMENT: Validity for lightness was fair to good, hue values were below 0.60. Reproducibility of lightness was good to very good for both reference systems. Hue values (VITAPAN Classical(®)) for 1.6 mm test specimens were upside, for 2.6 mm below 0.60, Kappa values for 3D-Master(®) were ≥0.60 for all measurements, reproducibility of chroma was very good. Validity was better for visual than for electronic color assessment. Reproducibility of the electronic device by means of the Shade Inspector™ was given for the VITAPAN Classical(®) and 3D-Master(®) systems.

  19. Experimental Study of Optimal Measurements for Quantum State Tomography

    Science.gov (United States)

    Sosa-Martinez, H.; Lysne, N. K.; Baldwin, C. H.; Kalev, A.; Deutsch, I. H.; Jessen, P. S.

    2017-10-01

    Quantum tomography is a critically important tool to evaluate quantum hardware, making it essential to develop optimized measurement strategies that are both accurate and efficient. We compare a variety of strategies using nearly pure test states. Those that are informationally complete for all states are found to be accurate and reliable even in the presence of errors in the measurements themselves, while those designed to be complete only for pure states are far more efficient but highly sensitive to such errors. Our results highlight the unavoidable trade-offs inherent in quantum tomography.

  20. Nonlinear Analysis of Experimental Measurements 7.6. Theoretical Chemistry

    Science.gov (United States)

    2015-01-26

    statistics of single molecule reaction trajectories and single cell microarray data (c) analysis of cytoadhesion and binding kinetics experiments; and (d...These research projects are motivated by single molecule measurements of complex biophysical processes, including photosynthetic energy transfer...enzymatic turnover reactions, and adhesion of cells. Single molecule experiments probe stochastic fluctuations on a broad range of temporal and spatial

  1. Performance measurement, expectancy and agency theory: An experimental study

    NARCIS (Netherlands)

    Sloof, R.; van Praag, C.M.

    2005-01-01

    Theoretical analyses of (optimal) performance measures are typically performed within the realm of the linear agency model. An important implication of this model is that, for a given compensation scheme, the agent's optimal effort choice is unrelated to the amount of noise in the performance

  2. Experimental measurement of effective atomic number of composite ...

    Indian Academy of Sciences (India)

    2011-08-02

    Aug 2, 2011 ... sample containers. They differed only in their heights. Therefore, the angle of acceptance was almost the same in each measurement. It may be argued that the multiple scattering of photons occurs whenever thick samples are used because such samples offer a larger mean free path for the incident ...

  3. Experimental measurement of the biomass of Olea europaea L ...

    African Journals Online (AJOL)

    The study was carried out in Central Italy and estimation of tree woody biomass and total biomass was made by direct measurement and through Intergovernmental Panel on Climate Change (IPCC) methodology. To determine the biomass of all the tree parts (including fruits and prunings) of the olive grove, the forestry ...

  4. Closure of digital arteries in high vascular tone states as demonstrated by measurement of systolic blood pressure in the fingers

    DEFF Research Database (Denmark)

    Krähenbühl, B; Nielsen, S L; Lassen, N A

    1977-01-01

    Finger systolic blood pressure (FSP) was measured indirectly in normal subjects and patients with primary Raynaud phenomenon by applying a thin-walled plastic cuff around the finger and a strain gauge more distally to detect volume changes. Inducing a high vascular tone in one or more fingers...... by direct cooling or intra-arterial noradrenaline infusion caused a marked drop in FSP in the exposed fingers, but not in the non-exposed fingers of the same hand. The fact that the non-exposed fingers retained the normal (arm systolic) pressure level is taken to indicate that palmar arch blood pressure...

  5. From gene to protein - experimental and clinical studies of ACE2 in blood pressure control and arterial hypertension

    Directory of Open Access Journals (Sweden)

    Sheila K Patel

    2014-06-01

    Full Text Available Hypertension is a major risk factor for stroke, coronary events, heart and renal failure, and the renin-angiotensin system (RAS plays a major role in its pathogenesis. Within the RAS, angiotensin converting enzyme (ACE converts angiotensin (Ang I into the vasoconstrictor Ang II. An alternate arm of the RAS now exists in which ACE2 counterbalances the effects of the classic RAS through degradation of Ang II, and generation of the vasodilator Ang 1-7. ACE2 is highly expressed in the heart, blood vessels and kidney. The catalytically active ectodomain of ACE2 undergoes shedding, resulting in ACE2 in the circulation. The ACE2 gene maps to a quantitative trait locus on the X chromosome in three strains of genetically hypertensive rats, suggesting that ACE2 may be a candidate gene for hypertension. It is hypothesised that disruption of tissue ACE/ACE2 balance results in changes in blood pressure, with increased ACE2 expression protecting against increased blood pressure, and ACE2 deficiency contributing to hypertension. Experimental hypertension studies have measured ACE2 in either the heart or kidney and/or plasma, and have reported that deletion or inhibition of ACE2 leads to hypertension, whilst enhancing ACE2 protects against the development of hypertension, hence increasing ACE2 may be a therapeutic option for the management of high blood pressure in man. There have been relatively few studies of ACE2, either at the gene or the circulating level in patients with hypertension. Plasma ACE2 activity is low in healthy subjects, but elevated in patients with cardiovascular risk factors or cardiovascular disease. Genetic studies have investigated ACE2 gene polymorphisms with either hypertension or blood pressure, and have produced largely inconsistent findings. This review discusses the evidence regarding ACE2 in experimental hypertension models and the association between circulating ACE2 activity and ACE2 polymorphisms with blood pressure and

  6. MR velocity mapping measurement of renal artery blood flow in patients with impaired kidney function

    DEFF Research Database (Denmark)

    Cortsen, M; Petersen, L.J.; Stahlberg, F

    1996-01-01

    . MR velocity mapping was performed in both renal arteries using an ECG-triggered gradient echo pulse sequence previously validated in normal volunteers. Effective renal plasma flow was calculated from the clearance rate of PAH during constant infusion and the split of renal function was evaluated...... by 99mTc-DTPA scintigraphy. A reduction of RBF was found, and there was a significant correlation between PAH clearance multiplied by 1/(1-hematocrit) and RBF determined by MR velocity mapping. Furthermore, a significant correlation between the distribution of renal function and the percent distribution...

  7. EXPERIMENTAL MEASUREMENTS OF TOWER CONSTRUCTION TILT USING ELECTRONIC TACHEOMETER

    Directory of Open Access Journals (Sweden)

    V. I. Mikhailov

    2015-01-01

    Full Text Available Modern tendencies for assessment of high-rise building deformation state presuppose creation of automated and regular monitoring while using highly-accurate space positioning systems (GPS-systems, a robotic electronic tacheometer, highlyaccurate inclinators (Leica Nivel210/Nivel220-model with measuring accuracy of tilt angle up to 0.09 s, Geomos software complex (Leica Geosystems. Automated system for deformation monitoring requires significant time and material expenditures, special training of specialists so simpler methods and criteria for assessment of building deformation state are also considered as rather actual for this purpose.There are more than ten conventional methods for determining building tilt. All these methods are based on angular measurements from the fixed base while using highly-accurate theodolites. The methods are rather labor-consuming and they do not provide operational efficiency and accuracy in measurements. Introduction of electronic tacheometers with large radius of refractorless measurements of distances has made it possible to calculate coordinates on the building surface with high accuracy and at various sections (heights that results in possibility to obtain 3D model of the building surface. Leica TCRA1201 tacheometer has been set at the good visibility point of a tower construction, device orientation and plane coordinates of the temporary point have been determined with the purpose to assess a tilt value of an exhaust stack having 150 meter height. Then 3D coordinates of six points on the building surface have been measured for every stack section. After that these points have been projected on the horizontal plane. LISCAD PLUS software complex has been used for processing and interpretation of geodetic data.The proposed method permits to obtain data for determination value and direction of a tower construction tilt, immediately carry out in-situ measurements and obtain final results in the automatic mode of

  8. "Calibration" system for spectral measurements and its experimental results

    Science.gov (United States)

    Bruchkouskaya, Sviatlana I.; Katkovsky, Leonid V.; Belyaev, Boris I.; Malyshev, Vladislav B.

    2017-04-01

    "Calibration" system has been developed at A. N. Sevchenko Research Institute of Applied Physical Problems of the Belarusian State University. It was designed for measuring the characteristics of spectral reflectance of all types of natural surfaces (test sites) in ground conditions or on board of aircraft carriers and has the following components: - Photospectroradiometr (PhSR) of high resolution with a range of 400-900 nm, equipped with a digital time-lapse video system; - Two-channel modular spectroradiometer (TMS) with a range of 400-900 nm, designed for simultaneous measurements of reflected light brightness of the underlying surface and the incident radiation from the upper hemisphere; - Two portable spectroradiometers (PSR-700 and PSR-1300) with a spectral range 800-1500 nm; 1200-2500 nm; - Scanning solar spectropolarimeter (SSP-600) with a range of 350-950 nm for measurements of direct sunlight and scattered by the atmosphere at different angles; "Calibration" system provides spectral resolution of 5.2 nm in a range of 400-900 nm, 10 nm in a range of 800-1500 nm and 15 nm in a range of 1200-2500 nm. Measurements of the optical characteristics of solar radiation (for determining parameters of the atmosphere) and that of underlying surface are synchronous. There is also a set of special nozzles for measurements of spectral brightness coefficients, polarization characteristics and spectral albedo. Spectra and images are geotagged to the navigation data (time, GPS). For the measurements of spectral reflection dependencies within "Monitoring-SG" framework expeditions to the Kuril Islands, Kursk aerospace test site and Kamchatka Peninsula were conducted in 2015 and 2016. The spectra of different underlying surfaces have been obtained: soils, plants and water objects, sedimentary and volcanic rocks. These surveys are a valuable material for further researches and selection of test facilities for flight calibration of space imaging systems. Information obtained

  9. A comparison of noninvasive blood pressure measurement on the wrist with invasive arterial blood pressure monitoring in patients undergoing bariatric surgery.

    Science.gov (United States)

    Hager, Helmut; Mandadi, Goutham; Pulley, Debra; Eagon, J Chris; Mascha, Edward; Nutter, Benjamin; Kurz, Andrea

    2009-06-01

    In morbidly obese patients, oscillometric blood pressure measurements with an upper-arm cuff are often difficult to perform. The alternative method, invasive blood pressure monitoring, can be difficult to place and is associated with risks. A wrist-mounted blood pressure-monitoring device, the Vasotrac, provides accurate blood pressure measurements in lean patients. Even in the obese, wrist morphology remains relatively unchanged. We thus assessed the degree to which blood pressure measurements with the Vasotrac on the wrist and cuff measurements agree with invasive arterial blood pressure monitoring. We evaluated 22 morbidly obese patients undergoing bariatric surgery lasting 3.8+/-1.1 h. Intraoperative blood pressure was simultaneously measured using the Vasotrac mounted on one wrist; an arterial catheter was inserted in the opposite radial artery, and an oscillometric cuff was positioned on the upper arm. Preoperative patient comfort was evaluated on a scale from 1 to 10, with 10 being most uncomfortable, just after the first oscillometric cuff inflation. Values from the Vasotrac and arterial catheter were recorded at 5-s intervals. Bias, precision, and clinically acceptable agreement were calculated between the two continuous monitoring devices and between the arterial catheter and the cuff measurements, with the arterial catheter providing the reference value. The patients' age was 44.3+/-9.5 years (mean+/-SD), body mass index was 66.7+/-13.8 kg/m2, and arm circumference was 48.6+/-7.5 cm. Patients found the Vasotrac more comfortable than the oscillometric device [1.7+/-1.8 vs 5.3+/-0.5 (P=0.009)]. A total of 40,411 pairs of values from the Vasotrac and arterial catheter were recorded. Lin's concordance correlation coefficient (95% CI) for mean arterial blood pressure measured between the arterial line and the Vasotrac was 0.74 (0.67, 0.82). The bias (mean error) was -0.25 mmHg; however, the Bland-Altman limits where 95% of individual pressure differences are

  10. Experimental viscosity measurements of biodiesels at high pressure

    Directory of Open Access Journals (Sweden)

    Schaschke C.J.

    2016-01-01

    Full Text Available The viscosity of biodiesels of soybean and rapeseed biodiesels blended with mineral diesel fuel were measured at pressures of up to 200 MPa. Using a falling sinker-type viscometer reproducible viscosity data were obtained based on the time taken for a sinker to descend a fixed distance down an enclosed tube under the influence of gravity. Measurements were taken using pressures which correspond to those of interest in automotive common rail diesel engines, and at temperatures of between 25ºC and 80ºC. In all cases, the viscosity of the biodiesel blends were found to increase exponentially for which the blends were noted as being more viscous than pure mineral fuels. A pressure-freezing effect was not observed for the blends.

  11. Experimental validation of a high voltage pulse measurement method.

    Energy Technology Data Exchange (ETDEWEB)

    Cular, Stefan; Patel, Nishant Bhupendra; Branch, Darren W.

    2013-09-01

    This report describes X-cut lithium niobates (LiNbO3) utilization for voltage sensing by monitoring the acoustic wave propagation changes through LiNbO3 resulting from applied voltage. Direct current (DC), alternating current (AC) and pulsed voltage signals were applied to the crystal. Voltage induced shift in acoustic wave propagation time scaled quadratically for DC and AC voltages and linearly for pulsed voltages. The measured values ranged from 10 - 273 ps and 189 ps 2 ns for DC and non-DC voltages, respectively. Data suggests LiNbO3 has a frequency sensitive response to voltage. If voltage source error is eliminated through physical modeling from the uncertainty budget, the sensors U95 estimated combined uncertainty could decrease to ~0.025% for DC, AC, and pulsed voltage measurements.

  12. A service quality experimental measure for public transport

    OpenAIRE

    Mazzulla, Gabriella; Eboli, Laura

    2006-01-01

    In this paper the importance of service quality attributes for public transport is estabilished by Importance Value calculation. Attribute weights (IV) are calculated by a specific empirical procedure in which a rate is assigned to each attribute according to the preferences of passengers. Finally, a Service Quality Index (SQI) for measuring the effectiveness of supplied services is calculated according to the main service quality attributes and their weights. This index can be us...

  13. Proteomic Expression Changes in Large Cerebral Arteries After Experimental Subarachnoid Hemorrhage in Rat Are Regulated by the MEK-ERK1/2 Pathway

    DEFF Research Database (Denmark)

    Müller, Anne H; Edwards, Alistair V G; Larsen, Martin R

    2017-01-01

    Subarachnoid hemorrhage (SAH) is a serious clinical condition where leakage of blood into the subarachnoid space causes an acute rise in intracranial pressure and reduces cerebral blood flow, which may lead to delayed cerebral ischemia and poor outcome. In experimental SAH, we have previously shown...... that the outcome can be significantly improved by early inhibition of the MAPK/ERK kinase/extracellular signal-regulated kinase (MEK/ERK1/2) pathway. The aim of this study was to apply mass spectrometry to investigate the overall late effects of experimental SAH on cerebrovascular protein expression. SAH...... was induced in rats that were treated with the MEK1/2 inhibitor U0126 or vehicle. Neurological outcome was assessed using a battery of behavioral tests. Specific protein expression of large cerebral arteries was analyzed quantitatively with high-throughput tandem mass spectrometry. SAH resulted in a marked...

  14. Uncalibrated pulse power analysis fails to reliably measure cardiac output in patients undergoing coronary artery bypass surgery.

    Science.gov (United States)

    Broch, Ole; Renner, Jochen; Höcker, Jan; Gruenewald, Matthias; Meybohm, Patrick; Schöttler, Jan; Steinfath, Markus; Bein, Berthold

    2011-01-01

    Uncalibrated arterial pulse power analysis has been recently introduced for continuous monitoring of cardiac index (CI). The aim of the present study was to compare the accuracy of arterial pulse power analysis with intermittent transpulmonary thermodilution (TPTD) before and after cardiopulmonary bypass (CPB). Forty-two patients scheduled for elective coronary surgery were studied after induction of anaesthesia, before and after CPB respectively. Each patient was monitored with the pulse contour cardiac output (PiCCO) system, a central venous line and the recently introduced LiDCO monitoring system. Haemodynamic variables included measurement of CI derived by transpulmonary thermodilution (CITPTD) or CI derived by pulse power analysis (CIPP), before and after calibration (CIPPnon-cal., CIPPcal.). Percentage changes of CI (ΔCITPTD, ΔCIPPnon-cal./PPcal.) were calculated to analyse directional changes. Before CPB there was no significant correlation between CIPPnon-cal. and CITPTD (r2 = 0.04, P = 0.08) with a percentage error (PE) of 86%. Higher mean arterial pressure (MAP) values were significantly correlated with higher CIPPnon-cal. (r2 = 0.26, P < 0.0001). After CPB, CIPPcal. revealed a significant correlation compared with CITPTD (r2 = 0.77, P < 0.0001) with PE of 28%. Changes in CIPPcal. (ΔCIPPcal.) showed a correlation with changes in CITPTD (ΔCITPTD) only after CPB (r2 = 0.52, P = 0.005). Uncalibrated pulse power analysis was significantly influenced by MAP and was not able to reliably measure CI compared with TPTD. Calibration improved accuracy, but pulse power analysis was still not consistently interchangeable with TPTD. Only calibrated pulse power analysis was able to reliably track haemodynamic changes and trends.

  15. Diffusion measurement of intraplaque hemorrhage and intramural hematoma using diffusion weighted MRI at 3T in cervical artery

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Bin [The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi (China); Yang, Li [Fudan University, Department of Radiology, Shanghai Institute of Medical Imaging, Zhongshan Hospital, Shanghai (China); Wang, Guangbin; Shi, Honglu; Wang, Shanshan; Li, Huihua [Shandong University, Shandong Medical Imaging Research Institute, Jinan, Shandong (China); Chen, Weibo; Chan, Queenie [Philips Healthcare, Shanghai (China)

    2016-10-15

    To assess the difference between carotid haemorrhagic plaque and non-haemorrhagic plaque by using diffusion-weighted imaging (DWI) and to evaluate carotid intraplaque haemorrhage (IPH) and intramural hematoma (IMH) of cervical artery dissection with apparent diffusion coefficient (ADC) measurement. Fifty-one symptomatic patients underwent 3.0-T carotid MR imaging, including conventional sequences, three-dimensional (3D) magnetization-prepared rapid acquisition gradient-echo (MPRAGE) sequence, and DWI. Thirty-nine patients with carotid plaque and eight patients with IMH of cervical artery dissection were finally included. The groups of hemorrhagic plaque, non-hemorrhagic plaque and IMH were divided according to 3D MPRAGE sequence. ADC values of different groups were measured, and t tests were performed. The mean ADC values of hemorrhagic plaques, non-hemorrhagic plaque and IMH were (1.284 ± 0.327) x 10{sup -3}mm{sup 2}/s, (1.766 ± 0.477) x 10{sup -3}mm{sup 2}/s, and (0.563 ± 0.119) x 10{sup -3}mm{sup 2}/s, respectively. The mean ADC values of hemorrhagic and non-hemorrhagic regions in the hemorrhagic plaque group were (0.985 ± 0.376) x 10{sup -3}mm{sup 2}/s and (1.480 ± 0.465) x 10{sup -3}mm{sup 2}/s, respectively. The differences between the hemorrhagic plaque and non-hemorrhagic plaque, hemorrhagic region and non-hemorrhagic region in hemorrhagic plaque, and the hemorrhagic region in the hemorrhagic plaque and IMH of artery dissection were significant (P < 0.05). DWI may be a useful complement to conventional MR imaging for identifying haemorrhage of carotid plaques and differentiate IMHs from IPH. (orig.)

  16. Linking the Grain Scale to Experimental Measurements and Other Scales

    Science.gov (United States)

    Vogler, Tracy

    2017-06-01

    A number of physical processes occur at the scale of grains that can have a profound influence on the behavior of materials under shock loading. Examples include inelastic deformation, pore collapse, fracture, friction, and internal wave reflections. In some cases such as the initiation of energetics and brittle fracture, these processes can have first order effects on the behavior of materials: the emergent behavior from the grain scale is the dominant one. In other cases, many aspects of the bulk behavior can be described by a continuum description, but some details of the behavior are missed by continuum descriptions. The multi-scale model paradigm envisions flow of information from smaller scales (atomic, dislocation, etc.) to the grain or mesoscale and the up to the continuum scale. A significant challenge in this approach is the need to validate each step. For the grain scale, diagnosing behavior is challenging because of the small spatial and temporal scales involved. Spatially resolved diagnostics have begun to shed light on these processes, and, more recently, advanced light sources have started to be used to probe behavior at the grain scale. In this talk, I will discuss some interesting phenomena that occur at the grain scale in shock loading, experimental approaches to probe the grain scale, and efforts to link the grain scale to smaller and larger scales. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE.

  17. Noninvasive measurement of arterial oxyhemoglobin saturation with a heated and a non-heated skin reflectance pulse oximeter sensor.

    Science.gov (United States)

    Mendelson, Y; Yocum, B L

    1991-01-01

    The feasibility of measuring arterial oxyhemoglobin saturation (SaO2) noninvasively using a skin reflectance pulse oximeter sensor attached to the scalp, neck, and thigh regions of anesthetized swine was investigated. The optical reflectance sensor used consisted of a pair of red and infrared light-emitting diodes and a concentric array of six identical photodiodes. Two prototype sensor assemblies were evaluated: one assembly housed only the optical sensor, whereas the other also included a miniature heater. Measurements made from the scalp and neck regions were obtained with the non-heated skin reflectance sensor, and measurements from the thigh were made with the heated prototype. Each sensor was interfaced to a commercial transmittance pulse oximeter adapted to perform as a reflectance pulse oximeter. SaO2 values obtained by the reflectance pulse oximeters (SpO2(r) were compared simultaneously with SaO2 values obtained from arterial blood samples and analyzed in vitro with a CO-oximeter. The equations for the best-fitted linear regression lines describing the relationships between SpO2(r) and SaO2 values in the range between 30 and 100% were: SpO2(r) = 10.7 + 0.90 (SaO2), n = 321, r = 0.97; SpO2(r) = 16.72 + 0.82 (SaO2), n = 217, r = 0.95; and SpO2(r) = 20.21 + 0.77 (SaO2), n = 37, r = 0.97 for the neck, thigh, and scalp measurements, respectively. The regression analysis revealed significant correlation and a relatively small standard error of estimate (SEE = 4.05% for the neck, 4.79% for the thigh, and 3.50% for the scalp measurements). This study demonstrated the feasibility of measuring SaO2 noninvasively over a wide range of values utilizing the principle of reflectance pulse oximetry.

  18. Changes of blood flow velocity indicating mechanical compression of the vertebral arteries during rotation of the head in the normal human measured with transcranial Doppler sonography

    OpenAIRE

    Rossiti, Sandro; Volkmann, Reinhard

    1995-01-01

    The dynamical changes of blood flow velocity of the intracranial vertebral arteries (VA's) and proximal basilar artery (BA) provoked by rotation of the head in normal volunteers were measured using pulsed-wave transcranial Doppler sonography (TCD). In another group both VA's were examined simultaneously with 2-channel TCD. Blood flow velocities diminished compared to the neutral position in all vessels, independently of die side. Total obstruction of the flow was not observed. Our findings re...

  19. Overview of the In-Flight Experimentations and Measurements on the IXV Experimental Vehicle

    Science.gov (United States)

    Cosson, E.; Giusto, S.; Del Vecchio, A.; Mancuso, S.

    2009-01-01

    After an assessment and then a trade-off of all the passenger experiments proposed by different partners within Europe, a selection of Core Experiments to be embarked on-board IXV to fulfil the Mission and System Requirements has been made. Some Passenger Experiments have also been identified to be potentially embarked, provided it is compatible with the system allocations, since they could bring valuable additional in-flight data. All those experiments include Thermal Protection System (TPS) experiments (including innovative TPS materials), AeroThermoDynamic (ATD) experiments and Health Monitoring System (HMS) experiments. Aside the previously mentioned experiments, a specific Vehicle Model Identification experiment (VMI) aims at validating in-flight the mathematical models of flight dynamics for a gliding re-entry vehicle. This paper also presents a preliminary version of the in- flight measurement plan, encompassing both conventional instrumentation and advanced sensors or even innovative measurement techniques.

  20. In vivo measurement of volumetric strain in the human brain induced by arterial pulsation and harmonic waves.

    Science.gov (United States)

    Hirsch, Sebastian; Klatt, Dieter; Freimann, Florian; Scheel, Michael; Braun, Jürgen; Sack, Ingolf

    2013-09-01

    Motion-sensitive phase contrast magnetic resonance imaging and magnetic resonance elastography are applied for the measurement of volumetric strain and tissue compressibility in human brain. Volumetric strain calculated by the divergence operator using a biphasic effective-medium model is related to dilatation and compression of fluid spaces during harmonic stimulation of the head or during intracranial passage of the arterial pulse wave. In six volunteers, phase contrast magnetic resonance imaging showed that the central cerebrum expands at arterial pulse wave to strain values of (2.8 ± 1.9)·10(-4). The evolution of volumetric strain agrees well with the magnitude of the harmonic divergence measured in eight volunteers by magnetic resonance elastography using external activation of 25 Hz vibration frequency. Intracranial volumetric strain was proven sensitive to venous pressure altered by abdominal muscle contraction. In eight volunteers, an increase in volumetric strain due to abdominal muscle contraction of approximately 45% was observed (P = 0.0001). The corresponding compression modulus in the range of 9.5-13.5 kPa demonstrated that the compressibility of brain tissue at 25 Hz stimulation is much higher than that of water. This pilot study provides the background for compression-sensitive magnetic resonance imaging with or without external head stimulation. Volumetric strain may be sensitive to fluid flow abnormalities or pressure imbalances between vasculature and parenchyma as seen in hydrocephalus. Copyright © 2012 Wiley Periodicals, Inc.

  1. Removal of Arsenic with Oyster Shell: Experimental Measurements

    Directory of Open Access Journals (Sweden)

    Md. Atiqur Rahman, , and

    2008-12-01

    Full Text Available Oyster shell has tremendous potential as a remediation material for the removal of arsenic from groundwater. A single arsenic removal system was developed with oyster shell for tube well water containing arsenic. The system removes arsenic from water by adsorption through fine oyster shell. Various conditions that affect the adsorption/desorption of arsenic were investigated. Adsorption column methods showed the removal of As(III under the following conditions: initial As concentration, 100 µg /L; oyster shell amount, 6 g; particle size, <355µm ; treatment flow rate, 1.7 mL/min; and pH 6.5. Arsenic concentration of the treated water were below the Bangladesh drinking water standard of 50 µg/L for As. The desorption efficiencies with 2M of KOH after the treatment of groundwater were in the range of 80-83%. A combination of techniques was used to measure the pH, conductivity, cations and anions. The average concentrations of other inorganic constituents of health concern (Na, K, Ca, Mg and Fe in treated water were below their respective WHO guideline for drinking. The present study might provide new avenues to achieve the arsenic concentrations required for drinking water recommended by Bangladesh and the World Health Organization (WHO.

  2. Reactivity to alcohol assessment measures: an experimental test.

    Science.gov (United States)

    Walters, Scott T; Vader, Amanda M; Harris, T Robert; Jouriles, Ernest N

    2009-08-01

    Previous research has suggested that alcohol screening and assessment may affect drinking. This study was a randomized test of reactivity to alcohol assessment questionnaires among a group of heavy drinking college students. A total of 147 university students completed a screening questionnaire and were randomized to either immediate assessment or delayed assessment. The immediate assessment group completed a set of drinking questionnaires at baseline, 3, 6 and 12 months, while the delayed assessment group completed questionnaires only at 12 months. Primary outcomes included overall volume of drinking, risky drinking and use of risk reduction behaviors. We found a significant effect of assessment on measures of risky drinking and risk reduction behaviors, but not on overall volume of drinking. Specifically, at 12 months, participants who had previously completed drinking assessments had a lower peak blood alcohol concentration (BAC) (d = -0.373), were more likely to report a low score on the Alcohol Use Disorders Identification Test (AUDIT; odds ratio = 2.55) and tended to use more strategies to moderate their alcohol consumption (d = 0.352). Risk reduction behaviors that were affected tended to be those that limited alcohol consumption, rather than those that minimized consequences. These results may have implications for the development of brief interventions.

  3. Oscillometric blood pressure measurement: a simple method in screening for peripheral arterial disease

    DEFF Research Database (Denmark)

    Mehlsen, Jesper; Wiinberg, Niels; Bruce, Christopher

    2008-01-01

    Blood pressure at the ankle level is a reliable indicator of peripheral arterial disease (PAD) and the ankle brachial index (ABI) is a useful non-invasive screening tool for the early detection of atherosclerosis. In the first part of the study, systolic blood pressures obtained by oscillometry...... and plethysmography were compared in 80 subjects referred for possible vascular disease. In the second part of the study, 31 general practitioners enrolled 1258 consecutive patients aged more than 60 years. ABI was estimated by oscillometry. Patients with an ABI lower than 0.9 were referred to the local hospital......, the oscillometry showed a positive predictive value of 47%. The presence of PAD was significantly correlated to exercise related leg pain, a diagnosis of hypertension and smoking, whereas no correlation could be found with a diagnosis of heart disease, stroke, or with the presence of diabetes. The prevalence...

  4. Non-pharmacological measures in preterm newborns submitted to arterial puncture

    Directory of Open Access Journals (Sweden)

    Gleicia Martins de Melo

    Full Text Available ABSTRACT Objective: to assess pain in preterm newborns and to compare the neonatal and therapeutic variables with the total scores of the Neonatal Facial Coding System of preterm newborns submitted to arterial puncture exposed to music and 25% oral glucose. Method: a comparative study with 48 recordings of preterm newborns - Group 1, music (26; Group 2, glucose 25% (22 - individually analyzed by three trained nurses, after Kappa of at least 80%. Results: the variables and the pain scores of the groups did not present statistical significance (p < 0.05 according to the Neonatal Facial Coding System. 80.8% of the preterm infants in Group 1 had a higher quantitative score ≥ 3 in the neonatal variables (gender, type of delivery, and therapeutic variables (type of oxygen therapy, place of hospitalization, type of puncture. Conclusion: There was no difference when comparing the music and glucose 25% groups and the variables studied.

  5. Repeatability of the measurement of augmentation index in the clinical assessment of arterial stiffness using radial applanation tonometry.

    Science.gov (United States)

    Crilly, M; Coch, C; Clark, H; Bruce, M; Williams, D

    2007-01-01

    Aortic augmentation index (AIx) measured using applanation tonometry is a non-invasive indicator of arterial stiffness. The objective of this study was to assess its repeatability when used by nurses with limited experience of the technique. Blood pressure/augmentation index (BP/AIx) was measured 4 times in 20 consecutive ambulant patients (16 male) after they rested supine for 15 min. Two nurses independently and alternately measured BP/AIx using the same equipment (Omron HEM-757; SphygmoCor with Millar hand-held tonometer). Nurses were blinded to patient medical records and their colleague's AIx/BP. 'Within' and 'between' observer differences were assessed using intra-class correlation coefficients (rI) and 95 % limits of agreement (95 % LoA) derived from Bland-Altman plots. Mean age was 56 (mean BP 136/79; mean pulse 64). Mean AIx was 24.1 (range 2.8 to 41.0). Both 'between' and 'within' observer repeatability was very high, with intra-class correlation coefficients ranging from 0.92 to 0.98. Mean AIx readings 'between' observers differed by only 0.68 (95 % CI -0.24 to 1.59) with a high rI (0.98; 95 % CI 0.95 to 0.99) and a narrow 95 % LoA (-3.22 to 4.57). The 95 % LoA for 'within' observer repeatability was -6.75 to 7.95. Differences in AIx measurement did not vary over time or with increasing levels of AIx. Even when undertaken by relatively inexperienced operators, both 'within' and 'between' observer repeatability of AIx measurement is very high. Such non-invasive assessment of arterial stiffness has the potential to be included in the clinical assessment of ambulant patients.

  6. Experimental quantum Zeno effect in NMR with entanglement-based measurement

    OpenAIRE

    Zheng, Wenqiang; Xu, D. Z.; Peng, Xinhua; Zhou, Xianyi; Du, Jiangfeng; Sun, C. P.

    2013-01-01

    We experimentally demonstrate a new dynamic fashion of quantum Zeno effect in nuclear magnetic resonance systems. The frequent measurements are implemented through quantum entanglement between the target qubit(s) and the measuring qubit, which dynamically results from the unitary evolution of duration $\\tau_{m}$ due to dispersive-coupling. Experimental results testify the presence of "the critical measurement time effect", that is, the quantum Zeno effect does not occur when $\\tau_{m}$ takes ...

  7. Experimental Measurement of the Flow Field of Heavy Trucks

    Energy Technology Data Exchange (ETDEWEB)

    Fred Browand; Charles Radovich

    2005-05-31

    trucks in a tandem configuration. In December 2003, such fuel consumption tests were performed at the same Crows Landing testsite. In the tests, two identical trucks are operated at headways in the range 3-10 meters. The trucks are steered by hand, but longitudinal control is provided by a closed-loop control system. Laser ranging measures truck-to-truck distance, and the control system maintains a truck separation to within about {+-} 3 centimeters. From these tests it is concluded that both trucks save fuel by close-following, that the fuel saving increases with decreasing spacing, and that the trail truck saves more fuel. An average value of fuel saving for each of the two trucks at spacings of 6-10 meters can be taken to be 3.0 liters/100 km.

  8. Peak velocity measurements in tortuous arteries with phase contrast magnetic resonance imaging: the effect of multidirectional velocity encoding.

    Science.gov (United States)

    Schubert, Tilman; Bieri, Oliver; Pansini, Michele; Stippich, Christoph; Santini, Francesco

    2014-04-01

    Blood flow velocity measurement with phase contrast magnetic resonance imaging (PC-MRI) is widely applied in clinical routine imaging. Usually, velocity and volumetric flow measurements are performed using unidirectional encoding of the through-plane velocity with a 2-dimensional (2D) acquisition. Single-slice acquisitions and measurements with unidirectional encoding, however, may lead to significant errors, especially in tortuous vessels, but might benefit from higher signal-to-noise ratios (SNRs). To evaluate the impact of volumetric acquisition and multidirectional velocity encoding, blood velocity measurements were performed at 3 locations in the distal internal carotid artery with a 3-dimensional, 3-directional time-resolved phase contrast (PC) sequence (4-dimensional [4D]) and a 2D acquisition with 3-directional (2D-3dir) and through-plane velocity encoding (2D-tp) derived from the same sequence. Twenty carotid arteries of 10 healthy volunteers (24-37 years) were evaluated. For each volunteer, 1 4D acquisition and 3 2D 3-directional PC measurements were placed according to a time-of-flight angiography. Unidirectionally encoded through-plane velocities were derived from the multidirectionally encoded 2D scan by discarding the in-plane components. Regions of interest were identified on the slab after postprocessing and visualization for the 4D data set as well as directly on the digital imaging and communications in medicine images for the 2D measurement. Blood flow velocity, volumetric flow, and SNRs were measured at carotid segments C4, C5, and C7 on both sides obtaining 20 values per vessel location. The quantities were tested for significant differences between each modality at all 3 locations with paired t tests. At the segments C5 and C7, the highest peak velocities (PVs) were measured with the 4D sequence, followed by 2D-3dir and 2D tp. The PV differences between the sequences were significant (P measured with 2D-tp. The mean PV value of the 4D sequence

  9. Evaluation of Wedged Arterial Injection as a New Technique for Delivery of Experimental Therapeutic Sustances into the Porcine Pancreas

    Directory of Open Access Journals (Sweden)

    Rafael Latorre

    2011-01-01

    Materials and Methods. Selective angiographies were completed in ten pigs under general anaesthesia. By superselective angiography, the catheter was inserted and wedged into the major pancreatic artery, blocking the blood flow. In order to evaluate the efficacy of the WAI method, a DNA-specific fluorescent dye (Hoechst 33258 was used. Results. Histological study revealed a uniform distribution of the fluorescent dye within the nuclei of the endocrine and exocrine pancreatic cells. Pancreatic and liver enzymes as well as histopathology of the pancreas were normal. Conclusion. WAI is a highly effective minimally invasive methodology to target the porcine pancreas. The findings suggest that WAI may contribute to developing preclinical assays of pancreas gene or cell-transfer therapies in swine model.

  10. [Measurement of Rho-kinase in peripheral blood monocytes in patients with pulmonary arterial hypertension related to chronic obstructive pulmonary diseases].

    Science.gov (United States)

    Cai, Qian; Wu, Shangjie; Zhao, Xuefeng

    2012-05-01

    To determine effects of the RhoA/Rho kinase signaling pathway on patients with pulmonary arterial hypertension related to chronic obstructive pulmonary diseases by testing levels of Rho-associated coiled-coil containing protein kinase 1(ROCK1) in peripheral blood monocytes in healthy subjects, patients with chronic obstructive pulmonary diseases (COPD), and patients with pulmonary arterial hypertension related to COPD. Ten healthy subjects (Group A), 10 patients with COPD (Group B), and 10 patients with pulmonary arterial hypertension related to COPD (Group C) were enrolled, all of whom were hospitalized in the Third Hospital of Changsha between Dec. 2010 and Apr. 2011. Twenty milliliters of blood was collected from each subject. The peripheral blood mononuclear cells (PBMC) were separated by Percoll and, monocytes were incubated. Levels of ROCK1 in the three groups were measured by ELISA. The pulmonary function was measured by spirometric tests, and the pulmonary arterial systolic pressure (PASP) was detected by color Doppler echocardiogram. 1)The PASP in Group C was significantly higher than that of Groups A and B(P0.05). Rho kinase plays a key role in the pathogenesis of pulmonary arterial hypertension. The ROCK1 may be a marker of the severity of pulmonary arterial hypertension related to COPD.

  11. Associations of Objectively Measured Physical Activity and Sedentary Time With Arterial Stiffness in Pre-Pubertal Children.

    Science.gov (United States)

    Haapala, Eero A; Väistö, Juuso; Veijalainen, Aapo; Lintu, Niina; Wiklund, Petri; Westgate, Kate; Ekelund, Ulf; Lindi, Virpi; Brage, Soren; Lakka, Timo A

    2017-08-01

    To investigate the relationships of objectively measured physical activity (PA) and sedentary time (ST) to arterial stiffness in prepubertal children. Altogether 136 children (57 boys, 79 girls) aged 6-8-years participated in the study. Stiffness index (SI) was assessed by pulse contour analysis based on photoplethysmography. ST, light PA, moderate PA, and vigorous PA were assessed using combined acceleration and heart rate monitoring. We investigated the associations of ST (<1.5METs) and time spent in intensity level of PA above 2-7METs in min/d with SI using linear regression analysis. We studied the optimal duration and intensity of PA to identify children being in the highest quarter of SI using Receiver Operating Characteristics curves. Moderate PA, vigorous PA, and cumulative time spent in PA above 3 (β=-0.279, p = .002), 4 (β =-0.341, P<0.001), 5 (β =-0.349, P<0.001), 6 (β =-0.312, P<0.001), and 7 (β =-0.254, p = .005) METs were inversely associated with SI after adjustment for age, sex, and monitor wear time. The cutoffs for identifying children being in the highest quarter of SI <68 min/d for PA exceeding 5 METs and <26 min/d for PA exceeding 6 METs. Lower levels of PA exceeding 3-6 METs were related to higher arterial stiffness in children.

  12. Comparison of fractional flow reserve measurements using intracoronary adenosine versus intracoronary sodium nitroprusside infusions in moderately stenotic coronary artery lesions

    Energy Technology Data Exchange (ETDEWEB)

    Safi, Morteza; Namazi, Mohammad Hasan; Fooladi, Esfandiar; Vakili, Hossein; Parsa, Saeed Alipour; Khaheshi, Isa [Cardiovascular Research Center, Modarres hospital, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of); Abbasi, Mohammad Amin [Department of Internal Medicine, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of); Movahed, Mohammad Reza, E-mail: rmova@aol.com [CareMore, Arizona, Tucson, AZ (United States); University of Arizona, Sarver Heart Center, Tucson, AZ (United States)

    2016-10-15

    Introduction: The aim of this study was to investigate the efficacy and safety of intracoronary (IC) sodium nitroprusside infusion in comparison to IC adenosine for fractional flow reserve (FFR) measurement in moderately diseased coronary artery lesions for functional assessment. Methods: During a nine month period, a consecutive of 98 patients with suspected or known coronary artery disease with moderate stenosis found during angiography (40% to 70% stenosis), were enrolled in this study. Hyperemia was induced by bolus doses of IC adenosine followed by sodium nitroprusside for FFR measurement. Results: Both IC adenosine and IC sodium nitroprusside induced similar and significant reduction in FFR. There was no statistically difference in FFR values between adenosine vs sodium nitroprusside infusions (mean FFR 84.3 ± 6.3 vs 85.7 ± 6.2, p = 0.1) respectively. Furthermore, comparing different FFR cut-off points between the groups (FFR < 0.75, 0.75–0.8 and > 0.8) showed no significant differences (p value = 0.7). Conclusion: An IC bolus of sodium nitroprusside (0.6 μg/kg) infusion induces a similar degree of hyperemia to IC bolus of 100–300 μg of adenosine. Therefore, IC sodium nitroprusside could be considered as an alternative drug to adenosine for FFR measurement with lower side effect profile. - Highlights: • Intracoronary (IC) sodium nitroprusside was compared with IC adenosine for FFR test. • IC adenosine and IC sodium nitroprusside induced similar reduction in FFR. • Different FFR cut-off points between the groups showed no significant differences. • IC sodium nitroprusside could be considered as an alternative to adenosine for FFR.

  13. Study of Anthropometric Measurements of the Anterior Ethmoidal Artery using Three-dimensional Scanning on 300 Patients

    Science.gov (United States)

    Bortoli, Vinicius Tomadon; Martins, Rafael Ferri; Negri, Krystal Calmeto

    2017-01-01

    Introduction The anterior ethmoidal artery (AEA) is one of the main arteries that supply both the nasal mucosa and the ethmoid sinuses. The AEA shows variability regarding its distance from adjacent structures. Several studies have developed techniques to identify the AEA. Objective This study aimed to compare the measurements from the AEA to the ethmoid bulla and to the frontal beak by using computed tomography of the face, while identifying their intraindividual and interindividual variations. Methods We analyzed 300 CT scans of the face performed at the CT scan Center at Hospital. The average age of subjects was 36 ± 15.1 years (range 4–84). Results We found that the average distance from the AEA to the ethmoid bulla was 17.2 ± 1.8 mm and the distance from the AEA to the frontal beak was 15.1 ± 2.2 mm. Regarding the average distance from the AEA to the frontal beak (AEA-frontal beak), there was a difference between the right and left sides, with the former being 0.4 mm higher on average than the latter. Among the age groups, there was a significant difference of distances between the AEA and the ethmoid bulla (AEA-ethmoid bulla), which were shorter in the ≤ 12 years group. There was a positive and significant correlation between both measurements analyzed, with low values (high) of AEA-ethmoid bulla distance corresponding to low values (high) of AEA-frontal beak distance. Conclusion The measurements obtained adds anatomical knowledge that can serve as a parameter in frontal and ethmoid sinus surgery. PMID:28382116

  14. Design and Development of a Testing Device for Experimental Measurements of Foundation Slabs on the Subsoil

    National Research Council Canada - National Science Library

    Čajka, Radim; Křivý, Vít; Sekanina, David

    2011-01-01

    The paper deals with technical solutions and construction of a testing stand designed for experimental measurements of deformations and state of stress of foundation structures placed on the subsoil...

  15. 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.

  16. Laser induced deflection technique for absolute thin film absorption measurement: optimized concepts and experimental results.

    Science.gov (United States)

    Mühlig, Christian; Kufert, Siegfried; Bublitz, Simon; Speck, Uwe

    2011-03-20

    Using experimental results and numerical simulations, two measuring concepts of the laser induced deflection (LID) technique are introduced and optimized for absolute thin film absorption measurements from deep ultraviolet to IR wavelengths. For transparent optical coatings, a particular probe beam deflection direction allows the absorption measurement with virtually no influence of the substrate absorption, yielding improved accuracy compared to the common techniques of separating bulk and coating absorption. For high-reflection coatings, where substrate absorption contributions are negligible, a different probe beam deflection is chosen to achieve a better signal-to-noise ratio. Various experimental results for the two different measurement concepts are presented.

  17. Measures of chronic kidney disease and risk of incident peripheral artery disease: a collaborative meta-analysis of individual participant data.

    Science.gov (United States)

    Matsushita, Kunihiro; Ballew, Shoshana H; Coresh, Josef; Arima, Hisatomi; Ärnlöv, Johan; Cirillo, Massimo; Ebert, Natalie; Hiramoto, Jade S; Kimm, Heejin; Shlipak, Michael G; Visseren, Frank L J; Gansevoort, Ron T; Kovesdy, Csaba P; Shalev, Varda; Woodward, Mark; Kronenberg, Florian

    2017-09-01

    Some evidence suggests that chronic kidney disease is a risk factor for lower-extremity peripheral artery disease. We aimed to quantify the independent and joint associations of two measures of chronic kidney disease (estimated glomerular filtration rate [eGFR] and albuminuria) with the incidence of peripheral artery disease. In this collaborative meta-analysis of international cohorts included in the Chronic Kidney Disease Prognosis Consortium (baseline measurements obtained between 1972 and 2014) with baseline measurements of eGFR and albuminuria, at least 1000 participants (this criterion not applied to cohorts exclusively enrolling patients with chronic kidney disease), and at least 50 peripheral artery disease events, we analysed adult participants without peripheral artery disease at baseline at the individual patient level with Cox proportional hazards models to quantify associations of creatinine-based eGFR, urine albumin-to-creatinine ratio (ACR), and dipstick proteinuria with the incidence of peripheral artery disease (including hospitalisation with a diagnosis of peripheral artery disease, intermittent claudication, leg revascularisation, and leg amputation). We assessed discrimination improvement through c-statistics. We analysed 817 084 individuals without a history of peripheral artery disease at baseline from 21 cohorts. 18 261 cases of peripheral artery disease were recorded during follow-up across cohorts (median follow-up was 7·4 years [IQR 5·7-8·9], range 2·0-15·8 years across cohorts). Both chronic kidney disease measures were independently associated with the incidence of peripheral artery disease. Compared with an eGFR of 95 mL/min per 1·73 m 2 , adjusted hazard ratios (HRs) for incident study-specific peripheral artery disease was 1·22 (95% CI 1·14-1·30) at an eGFR of 45 mL/min per 1·73 m 2 and 2·06 (1·70-2·48) at an eGFR of 15 mL/min per 1·73 m 2 . Compared with an ACR of 5 mg/g, the adjusted HR for incident study

  18. Ultrasonographic Measurement of the Diameter of a Normal Bile Duct, Hepatic Artery and Portal Vein in Infants Younger Than 3 Months

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    Kim, Sang Yoon; Lee, Young Seok [Dankook University Hospital, Cheonan (Korea, Republic of)

    2009-09-15

    This study focused on measuring the diameter of the normal bile duct, hepatic artery and portal vein with high resolution US in infants younger than 3 months, and we wanted to determine the relative ratio of these diameters. Fifty US examinations were performed on infants younger than 3 months and who did not have any clinical or laboratory abnormality associated with the hepatobiliary system. We measured the diameter of the bile duct, hepatic artery and portal vein at the level of the portal vein bifurcation with using 17-5 MHz US and we determined the relative ratios of these diameters. To evaluate the statistical difference in the diameter of the bile duct, hepatic artery and portal vein, we performed one-way ANOVA and Scheffe's multiple comparison test. To determine the relative ratio of these diameters, the ratio of the bile duct to the hepatic artery was defined as the hepatic artery/bile duct, the ratio of the hepatic artery to the portal vein was defined as the portal vein/hepatic artery and the ratio of the bile duct to the portal vein was defined as the portal vein/bile duct. We calculated the averages {+-} standard deviations of this data (minimum {approx} maximum). In all fifty infants, the bile duct, hepatic artery and portal vein were detectable and measurable. The average diameter of a bile duct was 0.85 {+-} 0.19 mm (0.56 {approx} 1.47 mm), it was 1.33 {+-} 0.31 mm (0.90 {approx} 2.37 mm) for the hepatic artery and 3.32 {+-} 0.68 mm (2.06 {approx} 5.08 mm) for the portal vein. The diameter of these structures was significantly different from each other according to one-way ANOVA (p < 0.001). The average diameter of the hepatic artery was significantly larger than that of the bile duct and the average diameter of the portal vein was significantly larger than that of bile duct and hepatic artery on Scheffe's multiple comparison test. The relative ratio of the bile duct to the hepatic artery was 1.60 {+-} 0.41 (0.77 {approx} 2.66), that of

  19. Validación del índice tobillo brazo oscilométrico comparado con eco-Doppler arterial de miembros inferiores para enfermedad arterial Validation of oscillometric measurement of ankle-brachial index compared with arterial lower limb echo-doppler for arterial disease

    Directory of Open Access Journals (Sweden)

    Astrid N Páez E

    2010-08-01

    Full Text Available INTRODUCCIÓN: estudios previos reportan la validación y correspondencia, o ambas, del índice tobillo brazo oscilométrico frente al índice tobillo brazo con Doppler, pero este último no corresponde al patrón de oro. OBJETIVO: determinar la validez de criterio del índice tobillo brazo oscilométrico comparado con la ecografía dúplex arterial de miembros inferiores para detectar enfermedad arterial periférica. METODOLOGÍA: estudio de evaluación de tecnologías diagnósticas realizado por muestreo transversal. De manera consecutiva, se reclutaron 101 personas del Instituto del Corazón de Bucaramanga con mínimo un factor de riesgo cardiovascular. Se midió el índice tobillo brazo oscilométrico con equipo OMRON® M7 HEM 780 y posteriormente se hizo ecografía dúplex arterial de miembros inferiores, esta última patrón de oro; los evaluadores estaban enmascarados. RESULTADOS: las mediciones repetidas de la presión arterial en cada miembro, mostraron una reproducibilidad casi perfecta, pues sus coeficientes de correlación intraclase son superiores a 0,86 y el acuerdo del método fue adecuado ± 15 mm Hg, para la mayoría de las mediciones. Según el análisis de la curva ROC, el punto de corte 90,48%, sensibilidad regular ( 70,37%, razón de probabilidad positiva cercana o superior al ideal (7-10, moderada calidad de la sensibilidad (0,58, sustancial calidad de la especificidad (0,66-0,78 y eficiencia o capacidad discriminatoria (0,62-0,67. CONCLUSIÓN: los hallazgos permiten recomendar la medición del índice tobillo brazo oscilométrico en personas con factores de riesgo cardiovasculares, como una prueba de rutina, bien sea para tamizaje (punto de corte INTRODUCTION: previous studies reported validation and/or correspondence of ankle-brachial index measured by OMRON (ABIO versus an ABI measured by Doppler, but the latter is not the gold standard. Objective: to determine the criterion validity of ABIO versus arterial duplex

  20. LB03.04: SPHYGMOMANOMETER CUFF CONSTRUCTION AND MATERIALS AFFECT TRANSMISSION OF PRESSURE FROM CUFF TO ARTERIAL WALL. FINITE ELEMENT ANALYSIS OF HUMAN PRESSURE MEASUREMENTS AND DICOM DATA.

    Science.gov (United States)

    Lewis, P; Naqvi, S; Mandal, P; Potluri, P

    2015-06-01

    Sphygmomanometer cuff pressure during deflation is assumed to equal systolic arterial pressure at the point of resumption of flow. Previous studies demonstrated that pressure decreases with increasing depth of soft tissues whilst visco-elastic characteristics of the arm tissue cause spatial and temporal variation in pressure magnitude. These generally used non-anatomical axisymmetrical arm simulations without incorporating arterial pressure variation. We used data from a volunteer's Magnetic Resonance (MR) arm scan and investigated the effect of variations in cuff materials and construction on the simulated transmission of pressure from under the cuff to the arterial wall under sinusoidal flow conditions. Pressure was measured under 8 different cuffs using Oxford Pressure Monitor Sensors placed at 90 degrees around the mid upper arm of a healthy male. Each cuff was inflated 3 times to 155 mmHg and then deflated to zero with 90 seconds between inflations. Young's modulus, flexural rigidity and thickness of each cuff was measured.Using DICOM data from the MR scan of the arm, a 3D model was derived using ScanIP and imported into Abaqus for Finite Element Analysis (FEA). Published mechanical properties of arm tissues and geometric non-linearity were assumed. The measured sub-cuff pressures were applied to the simulated arm and pressure was calculated around the brachial arterial wall. which was loaded with a sinusoidal pressure of 125/85 mmHg. FEA estimates of pressure around the brachial artery cuffs varied by up to 27 mmHg SBP and 17 mmHg DBP with different cuffs. Pressures within the cuffs varied up to 27 mmHg. Pressure transmission from the cuff to the arterial surface achieved a 95% transmission ratio with one rubber-bladdered cuff but varied between 76 and 88% for the others. Non-uniform pressure distribution around the arterial wall was strongly related to cuff fabric elastic modulus. Identical size cuffs with a separate rubber bladder produced peri-arterial

  1. Simultaneous measurement of brain perfusion and labeling efficiency in a single pseudo-continuous arterial spin labeling scan.

    Science.gov (United States)

    Chen, Zhensen; Zhao, Xihai; Zhang, Xingxing; Guo, Rui; Teeuwisse, Wouter M; Zhang, Bida; Koken, Peter; Smink, Jouke; Yuan, Chun; van Osch, Matthias J P

    2017-07-24

    The aim of this study was to propose, optimize, and validate a pseudo-continuous arterial spin labeling (pCASL) sequence for simultaneous measurement of brain perfusion and labeling efficiency. The proposed sequence incorporates the labeling efficiency measurement into the postlabeling delay period of a conventional perfusion pCASL sequence by using the time-encoding approach. In vivo validation experiments were performed on nine young subjects by comparing it to separate perfusion and labeling efficiency sequences. Sensitivity of the proposed combined sequence for measuring labeling efficiency changes was further addressed by varying the flip angles of the pCASL labeling radiofrequency pulses. The proposed combined sequence decreased the perfusion signal by ∼4% and a lower labeling efficiency (by ∼10%) was found as compared to the separate sequences. However, the temporal signal-noise-ratio of the perfusion signal remained unchanged. When the pCASL flip angle was decreased to a suboptimal setting, a strong correlation was found between the combined and the separate sequences for the relative change in pCASL perfusion signal as well as for the relative change in labeling efficiency. High correlation was also observed between relative changes in perfusion signal and the measured labeling efficiencies. The proposed sequence allows simultaneous measurement of brain perfusion and labeling efficiency with high time-efficiency at the price of only a small compromise in measurement accuracy. The additional labeling efficiency measurement can be used to facilitate qualitative interpretation of pCASL perfusion images. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  2. Renal frame count: a measure of renal flow that predicts success of renal artery stenting in hypertensive patients.

    Science.gov (United States)

    Naghi, Jesse; Palakodeti, Samhita; Ang, Lawrence; Reeves, Ryan; Patel, Mitul; Mahmud, Ehtisham

    2015-08-01

    Renal artery (RA) stenting can improve control of hypertension yet predicting clinical response remains difficult. We sought to determine the role of the renal frame count (RFC) (number of angiographic frames for contrast to reach distal renal parenchyma after initial RA opacification) as a predictor of improvement in blood pressure (BP) after RA stenting. Renal flow was quantified in 68 consecutive patients (age 72.5 ± 9.1 years, 72% male) undergoing RA stenting for refractory hypertension (BP ≥ 140/90 mm Hg despite treatment with two or more antihypertensive medications) by measuring RFC pre-RA stenting. Significant renal artery stenosis (RAS) was defined as a stenosis ≥ 70% by visual estimation on angiography. Baseline and 6-month follow-up BP was recorded. Clinical response was defined by a drop in systolic blood pressure (SBP) >10 mm Hg on the same or fewer number of anti-hypertensive medications. Patients with RFC > 30 had SBP reduction (43.2 ± 25.7 mm Hg vs. 30.1 ± 31.3 mm Hg, P = 0.067), diastolic blood pressure reduction (9.1 ± 19.0 vs. -0.2 ± 13.4 mm Hg, P = 0.02), and mean arterial pressure reduction (23.8 ± 19.4 vs. 11.8 ± 16.1 mm Hg, P 30 was associated with a higher rate of clinical response to RA stenting (93.5% vs. 73%, P = 0.027). RFC can be used as a clinical predictor of response to RA stenting. RFC > 30 was associated with reduction in BP after RA stenting and was predictive of clinical response. RFC provides a useful intraprocedural tool in assessing the severity of RAS and predicts the likelihood of clinical response following RA stenting. © 2015 Wiley Periodicals, Inc.

  3. Therapeutic effects of oral dimethyl fumarate on stroke induced by middle cerebral artery occlusion: An animal experimental study.

    Science.gov (United States)

    Safari, Anahid; Fazeli, Mehdi; Namavar, Mohammad Reza; Tanideh, Nader; Jafari, Peyman; Borhani-Haghighi, Afshin

    2017-01-01

    Dimethyl fumarate (DMF) has immune-modulatory and neuro-protective characteristics that can be used for treatment of acute ischemic stroke. To investigate the therapeutic effects of DMF on histological and functional recovery of rats after transient middle cerebral artery (MCA) occlusion. 22 Sprague-Dawley male rats weighing 275-300 g were randomized into three groups by block randomization. In the sham group (n = 7), the neck was opened, but neither MCA was occluded, nor any drug was administered.The control group (n = 7) was treated with vehicle (methocel) by gavage for 14 days after MCA occlusion. In the DMF-treated group (n = 8), treatment was performed with 15 mg/kg body weight dimethyl fumarate twice a day for 14 days after MCA occlusion. Transient occlusion of the right MCA was performed by intraluminal thread method in the DMF-treated and the control group. Neurological deficit score (NDS), pole test, and adhesive removal test were performed before the surgery, and on post-operative Days 0, 3, 5, 7, 10, and 14. After the final behaviour test, the animals' brains were perfused and removed. Brains were frozen and sectioned serially and coronally using a cryostat. Infract volume and brain volume were estimated by stereology. The percentage of infarct volume was significantly lower in DMF-treated animals (5.76%) than in the control group (22.39%) (P < 0.0001). Regarding behavioural tests, the DMF-treated group showed better function in NDS on Days 7 (P = 0.041) and 10 (P = 0.046), but not in pole and adhesive removal tests. There was no significant correlation between behavioural tests and histological results. Dimethyl fumarate could be beneficial as a potential neuroprotective agent in the treatment of stroke.

  4. Comparison of Wright's Formula and the Dunn Method for Measuring the Umbilical Arterial Catheter Insertion Length

    Directory of Open Access Journals (Sweden)

    Se-ra Min

    2015-04-01

    Conclusion: The use of Wright's formula overall results in superior correct placement of the UAC tip. It may be a more accurate and practical method than the conventional practice for measuring the UAC insertion length in newborns.

  5. Comparison of methods for measuring travel time at Florida freeways and arterials.

    Science.gov (United States)

    2014-07-01

    Travel time is an important performance measure used to assess the traffic operational quality of various types of highway : facilities. Previous research funded by the Florida Department of Transportation (FDOT) on travel time reliability developed,...

  6. Comparison of methods for measuring travel time at Florida freeways and arterials : [summary].

    Science.gov (United States)

    2014-07-01

    In this project, University of Florida researchers : collected field data along several highways to : evaluate travel time measurements from several : sources: STEWARD, BlueTOAD, INRIX, and HERE. : STEWARD (Statewide Transportation Engineering : Ware...

  7. Correlation between Echo-Tracking Parameters and In Vitro Measurements of Arterial Contraction and Relaxation in Rats Fed a High-Cholesterol Diet.

    Science.gov (United States)

    Zhang, Yi; Zhan, Wei-Wei; Wu, Yong-Jie; Zhao, Bo; Zhou, Wu-Gang; Chen, Dong-Rui; Zhou, Wei; Liu, Zhen-Hua; Jiang, Wei-Min; Zheng, Lin

    2015-09-30

    Echo-tracking (ET) is a new technique that allows the assessment of arterial function and stiffness. This study aimed to ascertain the utility of the echo-tracking (ET) technique to assess vascular stiffness in rats with hypercholesterolemia and atherosclerosis. ET was used to measure the arterial stiffness of the aorta in cholesterol-fed Sprague-Dawley rats (group T1, n=10, for 4 weeks; group T2, n=10, for 12 weeks) and normal control rats (group C1, n=10; group C2, n=10). In vitro isometric tension experiments were used to measure the maximum contractile tension (MCT) and maximum relaxation percentage (MRR%) of aortic rings. Indicators of arterial stiffness and aortic MCT and MRR% were compared between groups using linear regression analysis. Light microscopic evaluation was used to demonstrate atherosclerotic changes in the aorta. The rat models were successfully induced; pathological examination of the aortas showed significant atherosclerosis in group T2, but not in groups C1, C2, or T1. The arterial stiffness parameters obtained using ET and aortic rings in vitro showed significant impairments in T1 and T2 rats compared with C1 and C2 controls (all Pparameter b (r=-0.406, P=0.009) and one-point pulse wave β (r=-0.434, P=0.005). These results suggest that ET could be used to evaluate the changes in arterial wall elasticity associated with atherosclerosis and hypercholesterolemia.

  8. Experimental investigation and performance analysis of inertia properties measurement for heavy truck cab

    Directory of Open Access Journals (Sweden)

    Tianjun Zhu

    2015-11-01

    Full Text Available An experimental investigation and performance analysis of inertia properties measurement for heavy truck cab is presented. This method is specifically intended for measuring the inertia properties of irregular rigid bodies, and it has the potential to be applied to the measurement of the inertia properties of vehicle bodies, such as the cab, engine, and gearbox. This article, based on CATARC moment of inertia measurement system test rig, develops an accurate measuring method to identify inertia parameters of heavy truck cab. First, corresponding tests are carried out, and the lever principle and moments of inertia parallel theorem are employed to calculate and analyse the test results, which leads to the accurate value of inertia parameters. Second, the performance analysis of the proposed method is verified through the measurement error analysis. As a result, the proposed method shows high accuracy, which provides an experimental basis for accurate inertia parameter measurement of heavy truck cab.

  9. [Ultrasonographic evaluation of selected parameters of the endothelial function in brachial arteries and IMT measurements in carotid arteries in children with diabetes type 1 using personal insulin pumps--preliminary report].

    Science.gov (United States)

    Tołwińska, Joanna; Głowińska-Olszewska, Barbara; Urban, Mirosława; Florys, Bozena; Peczyńska, Jadwiga

    2006-01-01

    Type 1 diabetes is a known risk factor for arterial atherosclerosis. The first symptoms can be found even in childhood. The ultrasonographic measurements of intimal plus medial thickness in carotid arteries (IMT) and flow mediated dilatation (FMD) evaluated in brachial arteries, play a known role in the detection in these cases. The diabetes treatment intensification is an important factor in delaying early atherosclerotic changes. Currently, intensive treatment of children's diabetes with use of continuous subcutaneous insulin infusion with personal insulin pumps is gaining more and more popularity. THE AIM OF THIS STUDY was the evaluation of IMT and FMD indexes in children suffering from type 1 diabetes in the context of treatment intensification (multidose insulin injections v. personal insulin pumps). We examined 64 children (29 boys and 35 girls) in the mean age 15.5 years treated with the multidose insulin injections method and 10 children using personal insulin pumps (4 girls and 6 boys) in the mean age 14.5 years. Using high resolution ultrasonography we evaluated IMT values in carotid arteries and FMD parameters in brachial arteries. In our analysis we estimated the blood concentration of lipid parameters, values of systolic and diastolic blood pressure, the age of diabetes onset, duration time of the illness and the values of HbA1c as a marker of metabolic control. We noticed significantly higher FMD values in patients treated with personal insulin pumps (13.7 vs. 5.5%, p=0.001). IMT values were similar in both groups (0.52 vs. 0.5 mm, p=0. 41). The level of HDL cholesterol was higher and triglycerides lower in the group with treatment intensification. The metabolic control was the same in both groups. In patients treated by the multidose insulin injections IMT correlated with systolic blood pressure values. We didn't notice any correlation between IMT and FMD in any group. 1. Treatment intensification (personal insulin pumps) influences better vascular

  10. Comparison of temperature measurements in bladder, rectum and pulmonary artery in patients after cardiac surgery

    NARCIS (Netherlands)

    Wollerich, H.; Ismael, Farouq; Nijsten, Maarten; Dieperink, Willem

    2012-01-01

    In many patients in the intensive care unit (ICU) con-tinuous temperature monitoring is performed with rectal probes. Currently there are more options to measure temperature in critically ill patients. Since bladder catheters are routinely used in the majority of ICU patients, using bladder

  11. Pulmonary artery diameters, cross sectional areas and area changes measured by cine cardiovascular magnetic resonance in healthy volunteers.

    Science.gov (United States)

    Burman, Elisabeth D; Keegan, Jennifer; Kilner, Philip J

    2016-03-03

    We measured by cine cardiovascular magnetic resonance (CMR) main and branch pulmonary artery diameters and cross sectional areas in diastole and systole in order to establish normal ranges and the effects on them of age, gender and body surface area (BSA). Documentation of normal ranges provides a reference for research and clinical investigation in the fields of congenital heart disease, pulmonary hypertension and connective tissue disorders. We recruited 120 healthy volunteers: ten males (M) and ten females (F) in each decile between 20 and 79 years, imaging them in a 1.5 Tesla CMR system. Scout acquisitions guided the placement of steady state free precession cine acquisitions transecting the main, right and left pulmonary arteries (MPA, RPA and LPA). Cross sections were rarely quite circular. From all subjects, the means of the greater and lesser orthogonal diastolic diameters in mm were: MPA, 22.9 ± 2.4 (M) and 21.2 ± 2.1 (F), RPA 16.6 ± 2.8 (M) and 14.7 ± 2.2 (F), and LPA 17.3 ± 2.5 (M) and 15.9 ± 2.0 (F), p measurements of minimum diastolic and maximum systolic cross sectional areas, the % systolic distensions were: MPA 42.7 ± 17.2 (M) and 41.8 ± 15.7 (F), RPA 50.6 ± 16.9 (M) and 48.2 ± 14.5 (F), LPA 35.6 ± 10.1 (M) and 35.2 ± 10.3 (F), and there was a decrease in distension with age (p Measurements of MPA, RPA and LPA by cine CMR are provided for reference, with documentation of their changes with age and BSA.

  12. Threshold Setting for Likelihood Function for Elasticity-Based Tissue Classification of Arterial Walls by Evaluating Variance in Measurement of Radial Strain

    Science.gov (United States)

    Tsuzuki, Kentaro; Hasegawa, Hideyuki; Kanai, Hiroshi; Ichiki, Masataka; Tezuka, Fumiaki

    2008-05-01

    Pathologic changes in arterial walls significantly influence their mechanical properties. We have developed a correlation-based method, the phased tracking method [H. Kanai et al.: IEEE Trans. Ultrason. Ferroelectr. Freq. Control 43 (1996) 791], for measurement of the regional elasticity of the arterial wall. Using this method, elasticity distributions of lipids, blood clots, fibrous tissue, and calcified tissue were measured in vitro by experiments on excised arteries (mean±SD: lipids 89±47 kPa, blood clots 131 ±56 kPa, fibrous tissue 1022±1040 kPa, calcified tissue 2267 ±1228 kPa) [H. Kanai et al.: Circulation 107 (2003) 3018; J. Inagaki et al.: Jpn. J. Appl. Phys. 44 (2005) 4593]. It was found that arterial tissues can be classified into soft tissues (lipids and blood clots) and hard tissues (fibrous tissue and calcified tissue) on the basis of their elasticity. However, there are large overlaps between elasticity distributions of lipids and blood clots and those of fibrous tissue and calcified tissue. Thus, it was difficult to differentiate lipids from blood clots and fibrous tissue from calcified tissue by simply thresholding elasticity value. Therefore, we previously proposed a method by classifying the elasticity distribution in each region of interest (ROI) (not a single pixel) in an elasticity image into lipids, blood clots, fibrous tissue, or calcified tissue based on a likelihood function for each tissue [J. Inagaki et al.: Jpn. J. Appl. Phys. 44 (2006) 4732]. In our previous study, the optimum size of an ROI was determined to be 1,500 µm in the arterial radial direction and 1,500 µm in the arterial longitudinal direction [K. Tsuzuki et al.: Ultrasound Med. Biol. 34 (2008) 573]. In this study, the threshold for the likelihood function used in the tissue classification was set by evaluating the variance in the ultrasonic measurement of radial strain. The recognition rate was improved from 50 to 54% by the proposed thresholding.

  13. Measures of chronic kidney disease and risk of incident peripheral artery disease: a collaborative meta-analysis of individual participant data

    NARCIS (Netherlands)

    Matsushita, K.; Ballew, S.H.; Coresh, J.; Arima, H.; Arnlov, J.; Cirillo, M.; Ebert, N.; Hiramoto, J.S.; Kimm, H.; Shlipak, M.G.; Visseren, F.L.; Gansevoort, R.T.; Kovesdy, C.P.; Shalev, V.; Woodward, M.; Kronenberg, F.; Wetzels, J.F.M.; Grams, M.; Sang, Y.

    2017-01-01

    BACKGROUND: Some evidence suggests that chronic kidney disease is a risk factor for lower-extremity peripheral artery disease. We aimed to quantify the independent and joint associations of two measures of chronic kidney disease (estimated glomerular filtration rate [eGFR] and albuminuria) with the

  14. Impact of volunteer-related and methodology-related factors on the reproducibility of brachial artery flow-mediated vasodilation: analysis of 672 individual repeated measurements.

    NARCIS (Netherlands)

    Mil, A.C.C.M. van; Greyling, A.; Zock, P.L.; Geleijnse, J.M.; Hopman, M.T.E.; Mensink, R.P.; Reesink, K.D.; Green, D.J.; Ghiadoni, L.; Thijssen, D.H.J.

    2016-01-01

    OBJECTIVES: Brachial artery flow-mediated dilation (FMD) is a popular technique to examine endothelial function in humans. Identifying volunteer and methodological factors related to variation in FMD is important to improve measurement accuracy and applicability. METHODS: Volunteer-related and

  15. Measurements of Pulmonary Artery Size for Assessment of Pulmonary Hypertension by Cardiovascular Magnetic Resonance and Clinical Application

    Directory of Open Access Journals (Sweden)

    Fan YANG

    2017-02-01

    Full Text Available Background and objective Pulmonary hypertension (PH often leads to dilatation of main pulmonary artery (MPA. MPA measurements can be used to predict PH. This aim of this study is to investigate power of MPA vessel indices, which are acquired from cardiovascular magnetic resonance, to evaluate PH. Methods Cardiovascular-magnetic-resonance-determined parameters of MPA were acquired and calculated in 83 PH patients, whose diagnosis were confirmed with right heart catheterization and 49 healthy volunteers; these parameters included MPA diameter (DPA, ratio of DPA and ascending aorta diameter (DPA/DAo, max mean diameter (MDmax, min mean diameter (MDmin, fraction transverse diameter (fTD, fraction longitudinal diameter (fLD, and distensibility. Results Compared with control group, DPA, DPA/DAo, MDmax, and MDmin were significantly higher in patients with PH (P28.4 mm, and MDmax>32.4 mm (area under the curve, AUC=0.979, 0.981 showed best performance in predicting PH, yielding highest specificity at 100%. Conclusion Noninvasive cardiovascular-magnetic-resonance-derived MPA measurements provide excellent and practical reference in clinical settings for detecting PH.

  16. Relationship between clinical, 24-hour, average day-time and night-time blood pressure and measures of arterial stiffness in essential hypertension.

    Science.gov (United States)

    Rosa, J; Strauch, B; Petrák, O; Pikus, T; Holaj, R; Zelinka, T; Wichterle, D; Widimský, J

    2008-01-01

    Arterial wall stiffness is considered an independent cardiovascular risk factor. Aim of this study was to evaluate relationship between clinical, 24-hour, average day-time and night-time blood pressure (BP) and measures of arterial stiffness assessed by pulse wave velocity (PWV) (using SphygmoCor applanation tonometer) in essential hypertension (severe-resistant (RH, n=29) and moderate hypertension (EH, n=35)) and in normotensive control subjects (n-29) (NCS) matched by age. After multiple regression analysis, PWV remains significantly correlated mainly with night-time pulse pressure and to a lesser extent with age. PWV was significantly higher in RH compared to moderate EH and NCS.

  17. [Screening for asymptomatic peripheral arterial occlusive disease of the lower limbs by measuring the ankle-brachial index in the general population (Senegal)].

    Science.gov (United States)

    Pessinaba, S; Mbaye, A; Kane, Ad; Guene, B D; Mbaye Ndour, M; Niang, K; Jobe, M; Cazaubon, M; Mathieu, J-B S; Kane, M; Sow, D Diagne; Diack, B; Kane, A

    2012-07-01

    The purpose of this study was to investigate the prevalence of peripheral arterial disease (PAOD) and cardiovascular risk factors associated with the ankle-brachial index (ABI) in Senegalese patients aged 40 years and over. We prospectively studied a random sample of Senegalese aged 40 years and older, residing in the city of St.-Louis, Senegal. The ABI was measured with a portable doppler (DIADOP 50) using 4 and 8Hz dual frequency probes. The standards were: normal ABI 0.9 to 1.3; peripheral artery obstructive disease (PAOD) ABI less than 0.9; incompressible artery ABI greater than 1.3. Cardiovascular risk factors were also studied. Seven hundred and seventy-one subjects (mean age 57 ± 11.2 years, 559 women) were examined. Cardiovascular risk factors were: sedentary lifestyle (76.4%), hypertension (68%), obesity (32.1%), elevated LDL-cholesterolemia (27.8%), diabetes (18.3%) and tobacco smoking (6.9%). Ninety-three subjects (12.1%) had PAOD and 37 subjects (4.8%) had an incompressible artery. PAOD was significantly more common in sedentary subjects (P=0.008), in the elderly (P=0.0006) and in patients with a history of coronary artery disease (P=0.04). Smoking was not strongly associated with PAOD. PAOD is common in Senegalese and is associated with high prevalence of cardiovascular risk factors. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  18. Atypical nature of coronary artery disease in women: a proposal for measurement and classification

    Directory of Open Access Journals (Sweden)

    Viviana Marycel Céspedes Cuevas

    2015-01-01

    Full Text Available Objective: To identify subgroups of women with Acute Coronary Syndrome according to symptom experience: perception, evaluation and response, based on the Symptom Management Conceptual Model. Methodology: Quantitative, descriptive, exploratory, cross-sectional study. The sample was made of 380 women positively diagnosed with Acute Coronary Syndrome, hospitalized in two institutions in Bogotá, Colombia. A measurement instrument was designed and validated. Results: Final instrument was made of 37 items that reported content validity, scale validity, discriminant validity, and construct validity. A Cronbach's Alpha coefficient of 0,76 was obtained, which guarantees homogeneity in the measurement according to the Maximum Validity-Maximum Reliability Model. A total of 11 subgroups of women with Acute Coronary Syndrome were identified, those were characterized by atypical coronary heart disease symptomatology, evaluation processes related to extra-cardiac causes and inadequate symptom management strategies. It was possible to demonstrate that psychosocial factors, previous coronary heart disease and delays were variables making a significant influence on the components of symptom experience. Conclusions: Women with Acute Coronary Syndrome, belonging to the 11 subgroups that were identified and studied, showed atypical symptoms. The instrument designed features a proven psychometric quality; it was valid, reliable, and useful for clinical research and practice.

  19. [Computerized processing, using a Macintosh, of ambulatory arterial pressure measurements collected on a Spacelabs monitor].

    Science.gov (United States)

    Chanudet, X; Bauduceau, B; Leguicher, A; Celton, H; Larroque, P

    1987-06-01

    The use of the Spacelabs blood pressure recorder has given rise to processing programs running on Apple II and IBM PC computers. The authors have written in M.S. BASIC (2.1) a program who take advantage of graphic abilities and easy manipulation on Macintosh. The software was designed to perform three tasks: Communicating between Macintosh and Spacelabs station using serial interface (RS 232) without requesting specific interface card. Editing a report on two pages: The first is the listing of 96 measurements (one by 15 minutes). The second provides: patient identification, height, weight, diagnosis. Graphic representation of measurements Systolic and diastolic blood pressure (BP) repartition histogram for 24 hours, day and night. Standard deviation and mean of pressure and heart rate (HR) for those periods. A third optionally gives hourly chronogram and diagrams for cumulated BP and HR. Creating a file: 550 records can be stored on a 800 K floppy disk. The file handles: data for each patient (excepted identification). Random access and revision of each parameter is possible. comparative reports for group patients and patient by patient analysing data with appropriate statistical test (ANOVA and correlation) are done.

  20. Experimental measurement and numerical analysis on resonant characteristics of piezoelectric disks with partial electrode designs.

    Science.gov (United States)

    Lin, Yu-Chih; Ma, Chien-Ching

    2004-08-01

    Three experimental techniques are used in this study to access the influence of the electrode arrangement on the resonant characteristics of piezoceramic disks. These methods, including the amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI), laser Doppler vibrometer-dynamic signal analyzer (LDV-DSA), and impedance analysis, are based on the measurement of full-field displacement, pointwise displacement, and electric impedance, respectively. In this study, one full electrode design and three nonsymmetrical partial electrode designs of piezoelectric disks are investigated. Because the clear fringe patterns measured by the AF-ESPI method will be shown only at resonant frequencies, both the resonant frequencies and the corresponding vibration mode shapes are successfully obtained at the same time for out-of-plane and in-plane motions. The second experimental method is the impedance analysis, which is used to measure the resonant and antiresonant frequencies. In addition to these experimental methods, LDV-DSA is used to determine the resonant frequencies of the vibration mode with out-of-plane motion. From the experimental results, the dependence of electrode design on the vibration frequencies and mode shapes is addressed. Numerical computations based on the finite element method are presented, and the results are compared with the experimental measurements. The effect of different designs of electrode is more significant in the in-plane modes than that in the out-of-plane modes.

  1. Glomerular filtration rate measured by {sup 51}Cr-EDTA clearance: evaluation of captopril-induced changes in hypertensive patients with and without renal artery stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Chaves, Anna Alice Rolim; Buchpiguel, Carlos Alberto; Praxedes, Jose Nery; Bortolotto, Luiz Aparecido; Sapienza, Marcelo Tatit, E-mail: annaalice100@yahoo.com.b [Universidade de Sao Paulo (USP), SP (Brazil). Faculdade de Medicina. Dept. de Neurologia

    2010-07-01

    Introduction: renal artery stenosis can lead to renovascular hypertension; however, the detection of stenosis alone does not guarantee the presence of renovascular hypertension. Renovascular hypertension depends on activation of the renin-angiotensin system, which can be detected by functional tests such as captopril renal scintigraphy. A method that allows direct measurement of the baseline and post-captopril glomerular filtration rate using chromium-51 labeled ethylenediamine tetraacetic acid ({sup 51}Cr-EDTA) could add valuable information to the investigation of hypertensive patients with renal artery stenosis. The purposes of this study were to create a protocol to measure the baseline and post-captopril glomerular filtration rate using {sup 51}Cr-EDTA, and to verify whether changes in the glomerular filtration rate permit differentiation between hypertensive patients with and without renal artery stenosis. Methods: this prospective study included 41 consecutive patients with poorly controlled severe hypertension. All patients had undergone a radiological investigation of renal artery stenosis within the month prior to their inclusion. The patients were divided into two groups: patients with (n=21) and without renal artery stenosis, (n=20). In vitro glomerular filtration rate analysis ({sup 51}Cr-EDTA) and {sup 99m}Tc-DMSA scintigraphy were performed before and after captopril administration in all patients. Results: the mean baseline glomerular filtration rate was 48.6+-21.8 ml/kg/1.73 m{sup 2} in the group with renal artery stenosis, which was significantly lower than the GFR of 65.1+-28.7 ml/kg/1.73m{sup 2} in the group without renal artery stenosis (p=0.04). Captopril induced a significant reduction of the glomerular filtration rate in the group with renal artery stenosis (to 32.6+-14.8 ml/kg/1.73m{sup 2}, p=0.001) and an insignificant change in the group without RAS (to 62.2+-23.6 ml/kg/1.73m{sup 2}, p=0.68). Scintigraphy with technetium-99m dimercapto

  2. Glomerular filtration rate measured by 51Cr-EDTA clearance: evaluation of captopril-induced changes in hypertensive patients with and without renal artery stenosis

    Directory of Open Access Journals (Sweden)

    Anna Alice Rolim Chaves

    2010-01-01

    Full Text Available INTRODUCTION: Renal artery stenosis can lead to renovascular hypertension; however, the detection of stenosis alone does not guarantee the presence of renovascular hypertension. Renovascular hypertension depends on activation of the renin-angiotensin system, which can be detected by functional tests such as captopril renal scintigraphy. A method that allows direct measurement of the baseline and post-captopril glomerular filtration rate using chromium-51 labeled ethylenediamine tetraacetic acid (51Cr-EDTA could add valuable information to the investigation of hypertensive patients with renal artery stenosis. The purposes of this study were to create a protocol to measure the baseline and post-captopril glomerular filtration rate using 51Cr-EDTA, and to verify whether changes in the glomerular filtration rate permit differentiation between hypertensive patients with and without renal artery stenosis. METHODS: This prospective study included 41 consecutive patients with poorly controlled severe hypertension. All patients had undergone a radiological investigation of renal artery stenosis within the month prior to their inclusion. The patients were divided into two groups: patients with (n=21 and without renal artery stenosis, (n=20. In vitro glomerular filtration rate analysis (51Cr-EDTA and 99mTc-DMSA scintigraphy were performed before and after captopril administration in all patients. RESULTS: The mean baseline glomerular filtration rate was 48.6±21.8 ml/kg/1.73 m² in the group wuth renal artery stenosis, which was significantly lower than the GFR of 65.1±28.7 ml/kg/1.73m² in the group without renal artery stenosis (p=0.04. Captopril induced a significant reduction of the glomerular filtration rate in the group with renal artery stenosis (to 32.6±14.8 ml/kg/1.73m², p=0.001 and an insignificant change in the group without RAS (to 62.2±23.6 ml/kg/1.73m², p=0.68. Scintigraphy with technetium-99m dimercapto-succinic acid (DMSA did not show

  3. Photoplethysmography and ultrasonic-measurement-integrated simulation to clarify the relation between two-dimensional unsteady blood flow field and forward and backward waves in a carotid artery.

    Science.gov (United States)

    Sone, Shusaku; Hayase, Toshiyuki; Funamoto, Kenichi; Shirai, Atsushi

    2017-05-01

    Understanding the spatiotemporal change in hemodynamics is essential for the basic research of atherosclerosis. The objective of this study was to establish a methodology to clarify the relation between a two-dimensional (2D) unsteady blood flow field and forward and backward propagating waves in a carotid artery. This study utilized photoplethysmography (PPG) for blood pressure measurement and two-dimensional ultrasonic-measurement-integrated (2D-UMI) simulation for flow field analysis. The validity of the methodology was confirmed in an experiment for a carotid artery of a healthy volunteer. Synchronization between the pressure measurement and flow field analysis was achieved with an error of flow field in the carotid artery was characterized in relation to forward and backward waves. 2D-UMI simulation reproduced the flow field in which the wall shear stress takes a maximum at the time of the backward wave superiority in the systolic phase, whereas 2D ordinary simulation failed to reproduce this feature because of poor reproducibility of velocity distribution. In conclusion, the proposed methodology using PPG and 2D-UMI simulation was shown to be a potential tool to clarify the relation between 2D unsteady blood flow field and the forward and backward waves in a carotid artery.

  4. Experimental Test of the State Estimation-Reversal Tradeoff Relation in General Quantum Measurements

    Directory of Open Access Journals (Sweden)

    Geng Chen

    2014-06-01

    Full Text Available When a measurement has limited strength, only partial information, regarding the initial state, is extracted, and, correspondingly, there is a probability to reverse its effect on the system and retrieve the original state. Recently, a clear and direct quantitative description of this complementary relationship, in terms of a tradeoff relation, was developed by Y. K. Cheong and S. W. Lee. [Phys. Rev. Lett. 109, 150402 (2012]. Here, this tradeoff relation is experimentally verified using polarization-encoded single photons from a quantum dot. Measurement operators representing a complete range, from not affecting the system to a projection to a single polarization state, are realized. In addition, for each measurement operator, an optimal reversal operator is also implemented. The upper bound of the tradeoff relation is mapped to experimental parameters representing the measurement strength. Our results complement the theoretical work and provide a hands-on characterization of general quantum measurements.

  5. A proposed experimental method for interpreting Doppler effect measurements and determining their precision

    Science.gov (United States)

    Klann, P. G.

    1973-01-01

    The principal problem in the measurement of the Doppler reactivity effect is separating it from the thermal reactivity effects of the expansion of the heated sample. It is shown in this proposal that the thermal effects of sample expansion can be experimentally determined by making additional measurements with porous samples having the same mass and/or volume as the primary sample. By combining these results with independent measurements of the linear temperature coefficient and the computed temperature dependence of the Doppler coefficient the magnitude of the Doppler coefficient may be extracted from the data. These addiational measurements are also useful to experimentally determine the precision of the reactivity oscillator technique used to measure the reactivity effects of the heated sample.

  6. Optimization of the scan protocol in the measurements of coronary artery calcium

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, L.C.G.; Lopes, R.T. [Coordenacao do Programa de Pos-graduacao em Engenharia (LIN/COPPE/UFRJ), RJ (Brazil). Lab. de Instrumentacao Nuclear; Gottlieb, I.; Carvalho, F.M. de [Clinica de Diagnostico por Imagem, Rio de Janeiro, RJ (Brazil); Kodlulovich, S., E-mail: simone@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Mecca, F.A. [Instituto Nacional do Cancer (INCA), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    The aim of this study was to evaluate the influence of the tube current applied for studies of calcium score. The research was carried out in a private clinic of Rio de Janeiro, using a 64-slice MDCT scanner and an anthropomorphic cardiac CT phantom. In all images, the Agatston score, the volume and mass of the calcifications, and the noise for each current tube was determined. The average CT attenuation number obtained for all tube currents was 261.6 {+-} 3.2 HU for the CaHA density insert and -0.2 HU {+-} 2.0 for the water insert. The images obtained at lower tube currents were noisier and grainier than those obtained at higher tube currents. However no significant differences were found in the calcium measurements, which suggest a high potential of patient dose reduction, around 50%, without compromising diagnostic information. (author)

  7. Attenuation of laser generated ultrasound in steel at high temperatures; comparison of theory and experimental measurements.

    Science.gov (United States)

    Kube, Christopher M

    2016-08-01

    This article reexamines some recently published laser ultrasound measurements of the longitudinal attenuation coefficient obtained during annealing of two steel samples (DP600 and S550). Theoretical attenuation models based on perturbation theory are compared to these experimental measurements. It is observed that the Rayleigh attenuation formulas provide the correct qualitative agreement, but overestimate the experimental values. The more general theoretical attenuation model considered here demonstrates strong quantitative agreement, which highlights the applicability of the model during real-time metal processing. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Comparison of the non-invasive Nexfin® monitor with conventional methods for the measurement of arterial blood pressure in moderate risk orthopaedic surgery patients.

    Science.gov (United States)

    Balzer, Felix; Habicher, Marit; Sander, Michael; Sterr, Julian; Scholz, Stephanie; Feldheiser, Aarne; Müller, Michael; Perka, Carsten; Treskatsch, Sascha

    2016-08-01

    Continuous invasive arterial blood pressure (IBP) monitoring remains the gold standard for BP measurement, but traditional oscillometric non-invasive intermittent pressure (NIBP) measurement is used in most low-to-moderate risk procedures. This study compared non-invasive continuous arterial BP measurement using a Nexfin® monitor with NIBP and IBP monitors. This was a single-centre, prospective, pilot study in patients scheduled for elective orthopaedic surgery. Systolic BP, diastolic BP and mean arterial blood pressure (MAP) were measured by Nexfin®, IBP and NIBP at five intraoperative time-points. Pearson correlation coefficients, Bland-Altman plots and trending ability of Nexfin® measurements were used as criteria for success in the investigation of measurement reliability. A total of 20 patients were enrolled in the study. For MAP, there was a sufficient correlation between IBP/Nexfin® (Pearson = 0.75), which was better than the correlation between IBP/NIBP (Pearson = 0.70). Bland-Altman analysis of the data showed that compared with IBP, there was a higher percentage error for MAPNIBP (30%) compared with MAPNexfin® (27%). Nexfin® and NIBP underestimated systolic BP; NIBP also underestimated diastolic BP and MAP. Trending ability for MAPNexfin® and MAPNIBP were comparable to IBP. Non-invasive BP measurement with Nexfin® was comparable with IBP and tended to be more precise than NIBP. © The Author(s) 2016.

  9. Measurement of free radicals using electron paramagnetic resonance spectroscopy during open aorto-iliac arterial reconstruction.

    Science.gov (United States)

    Majewski, Wacław; Krzyminiewski, Ryszard; Stanisić, Michał; Iskra, Maria; Krasiński, Zbigniew; Nowak, Marek; Dobosz, Bernadeta

    2014-11-27

    Aortic cross-clamping during abdominal aortic aneurysm (AAA) open repair leads to development of ischemia-reperfusion injury. Electron paramagnetic resonance spectroscopy (EPR) spin-trapping is a valuable method of direct measurement of free radicals. The objective of the study was to evaluate the results of EPR as a direct method of free radical measurement and degree of inflammatory response in open operative treatment of patients with AAA and aorto-iliac occlusive disease (AIOD). The study was performed on a group of 32 patients with AAA and 25 patients with AIOD scheduled for open repair. Peripheral venous blood for EPR spectroscopy and for SOD, GPx, ox-LDL, Il-6, TNF-alfa, CRP, and HO-1 were harvested. Selected parameters were established accordingly to specified EPR and immunohistochemical methods and analyzed between groups by Mann-Whitney U test and Wilcoxon matched-pairs signed-ranks test with Bonferroni correction. Free radicals level was correlated with the time of the aortic cross-clamping after the reperfusion of he first and second leg in AAA (r=0.7; r=0.47). ox-LDL in AAA decreased 5 min after reperfusion of the first leg (32.99 U/L, range: 14.09-77.12) and 5 min after reperfusion of the second leg (26.75 U/L, range: 11.56-82.12) and 24 h after the operation (25.85 U/L, range: 14.29-49.70). HO-1 concentration increased to above the level before intervention 24 h after surgery. The activities of GPx and SOD decreased 5 min after the first-leg reperfusion in AAA. Twenty-four hours after surgery, inflammatory markers increased in AAA to CRP was 14.76 ml/l (0.23-38.55), IL-6 was 141.22 pg/ml (84.3-591.03), TNF-alfa was 6.82 pg/ml (1.76-80.01) and AIOD: CRP was 18.44 mg/l (2.56-33.14), IL-6: 184.1 pg/ml (128.46-448.03), TNF-alfa was 7.74 pg/ml (1.74-74.74). EPR spin-trapping demonstrates temporarily elevated level of free radicals in early phase of reperfusion, leading to decrease antioxidants in AAA. Elevated free radical levels decreased 24 h after

  10. Association of the Fractal Dimension of Retinal Arteries and Veins with Quantitative Brain MRI Measures in HIV-Infected and Uninfected Women.

    Science.gov (United States)

    Crystal, Howard A; Holman, Susan; Lui, Yvonne W; Baird, Alison E; Yu, Hua; Klein, Ronald; Rojas-Soto, Diana Marcella; Gustafson, Deborah R; Stebbins, Glenn T

    2016-01-01

    The fractal dimension of retinal arteries and veins is a measure of the complexity of the vascular tree. We hypothesized that retinal fractal dimension would be associated with brain volume and white matter integrity in HIV-infected women. Nested case-control within longitudinal cohort study. Women were recruited from the Brooklyn site of the Women's Interagency HIV study (WIHS); 34 HIV-infected and 21 HIV-uninfected women with analyzable MRIs and retinal photographs were included. Fractal dimension was determined using the SIVA software program on skeletonized retinal images. The relationship between predictors (retinal vascular measures) and outcomes (quantitative MRI measures) were analyzed with linear regression models. All models included age, intracranial volume, and both arterial and venous fractal dimension. Some models were adjusted for blood pressure, race/ethnicity, and HIV-infection. The women were 45.6 ± 7.3 years of age. Higher arterial dimension was associated with larger cortical volumes, but higher venous dimension was associated with smaller cortical volumes. In fully adjusted models, venous dimension was significantly associated with fractional anisotropy (standardized β = -0.41, p = 0.009) and total gray matter volume (β = -0.24, p = 0.03), and arterial dimension with mean diffusivity (β = -0.33,.p = 0.04) and fractional anisotropy (β = 0.34, p = 0.03). HIV-infection was not associated with any retinal or MRI measure. Higher venous fractal dimension was associated with smaller cortical volumes and lower fractional anisotropy, whereas higher arterial fractal dimension was associated with the opposite patterns. Longitudinal studies are needed to validate this finding.

  11. A Novel System for Measuring Optical Properties in Arterial Blood of Man

    Directory of Open Access Journals (Sweden)

    A. Castañeda-Miranda

    2006-01-01

    Full Text Available The necessity of man–machine communication has been increasing day by day because of the great number of approaches that help to make human life agile or comfortable. Health is one of the aspects that has generated more interest in recent years. The optical technologies are new technical tools that are being implemented for medical diagnosis and for describing various processes occurring within human blood. These techniques have the virtue of being nondestructive; in addition they have the advantage of remote direction by using an in situ technique, with sensitivity capable of studying the properties of the blood through electromagnetic excitation. A device to obtain the electromagnetic spectrum in the blood has being designed and is presented in this work. This device uses a quartz lamp, emitting electromagnetic radiation between 200 nm and 2200 nm. A model for measuring the light attenuation through the blood is used. By applying a control in the frequency domain, a circuit device is designed. This device uses a database in time domain for its subsequent analysis by Fast Fourier Transformation in order to obtain absorption spectra. The acquisition time is of the order of microseconds, and the system is controlled automatically through accessible software from a personal computer.

  12. Performance of recommended measures on risk factors control in patients with hypertension, coronary artery disease and chronic heart failure: the data from 2014 Russian registry

    Directory of Open Access Journals (Sweden)

    Posnenkova O.M.

    2015-03-01

    Full Text Available A report presents the results of evaluation of recommended measures on risk factors control in patients with hypertension, stable coronary artery disease (CAD and chronic heart failure (CHF. The performance of recommended measures was assessed with the help of specially developed system of clinical indicators on the basis of data of the year 2014 from patients enrolled in multicenter Russian registry of hypertension, CAD and CHF.

  13. Echocardiographic estimation of right ventricular stroke work in children with pulmonary arterial hypertension: comparison with invasive measurements.

    Science.gov (United States)

    Di Maria, Michael V; Burkett, Dale A; Younoszai, Adel K; Landeck, Bruce F; Mertens, Luc; Ivy, D Dunbar; Friedberg, Mark K; Hunter, Kendall S

    2015-11-01

    Right ventricular (RV) failure is a key determinant of mortality in children with pulmonary arterial hypertension (PAH). RV stroke work (RVSW) can be estimated as the product of RV systolic pressure and stroke volume. The authors have shown that RVSW predicts adverse outcomes in this population when derived from hemodynamic data; noninvasive assessment of RVSW may be advantageous but has not been assessed. There are few data validating noninvasive versus invasive measurements in children with PAH. The aim of this study was to compare echocardiographically derived RVSW with RVSW determined from hemodynamic data. This was a retrospective study, including subjects with idiopathic PAH and minor or repaired congenital heart disease. Forty-nine subjects were included, in whom cardiac catheterization and echocardiography were performed within 1 month. Fourteen additional patients were included in a separate cohort, in whom catheterization and echocardiography were performed simultaneously. Catheterization-derived RVSW was calculated as RV systolic pressure × (cardiac output/heart rate). Echocardiographically derived RVSW was calculated as 4 × (peak tricuspid regurgitant jet velocity)(2) × (pulmonary valve area × velocity-time integral). Statistics included the intraclass correlation coefficient and Bland-Altman analysis. Echocardiographically derived RVSW was linearly correlated with invasively derived RVSW (r = 0.74, P rights reserved.

  14. Morphologic expression of the left coronary artery in pigs. An approach in relation to human heart

    Directory of Open Access Journals (Sweden)

    Fabian Alejandro Gómez

    2014-04-01

    Full Text Available Introduction: In spite of its importance as an experimental model, the information on the left coronary artery in pigs is sparse. Objective: To determine the morphologic features of the left coronary artery in pigs. Methods: We evaluated 158 pig hearts. The left coronary artery was perfused with synthetic resin after their ostia had been catheterized. Diameters and courses of the vascular beds were measured with an electronic caliper (Mitutoyo(r. Results: The diameter of left coronary artery was 6.98 ± 1.56 mm and its length was 3.51±0.99 mm. It was found to end up by bifurcating itself into the anterior interventricular artery and the circumflex artery in 79% of the cases, and by trifurcating in 21% of the cases, with the presence of the diagonal artery. The anterior interventricular artery ended up at the apex in 79.7% of the cases, and the circumflex artery at the posterior aspect of the left ventricle in 64% of the case, this artery never reached the posterior interventricular sulcus. An anastomosis between the terminal branches of the anterior interventricular artery and the posterior interventricular artery was found in 7.6% of the specimens. The antero-superior branch of the anterior interventricular artery occurred in 89.9% of the hearts. A left marginal branch was observed in 87.9% of the cases with a diameter of 2.25±0.55 mm. Conclusion: Compared with humans, pigs have shorter left coronary artery trunks and branches; even the circumflex artery never reaches the posterior interventricular sulcus. Our findings are useful for the design of experimental hemodynamic and procedural models.

  15. Role of arterial baroreceptors in mediating cardiovascular response to exercise

    Science.gov (United States)

    Mcritchie, R. J.; Vatner, S. F.; Patrick, T. A.; Braunwald, E.; Boettcher, D.; Heyndrickx, G. R.

    1976-01-01

    Experiments were conducted to define the role of the major arterial baroreceptors during moderately severe exercise by comparing the responses of untethered conscious dogs instrumented for the measurement of aortic pressure and cardiac output with those of dogs with total arterial baroreceptor denervation. The reflex heart rate responses to intravenous bolus doses of methoxamine were also examined in intact animals, both at rest and during exercise. Methoxamine is found to cause striking bradycardia at rest, but little bradycardia during exercise. Experimental findings suggest that the arterial baroreceptor reflex is normally inhibited during severe exercise and therefore plays little role in modulating the cardiovascular response to exercise.

  16. An Integrative Model of the Cardiovascular System Coupling Heart Cellular Mechanics with Arterial Network Hemodynamics

    Science.gov (United States)

    Kim, Young-Tae; Lee, Jeong Sang; Youn, Chan-Hyun; Choi, Jae-Sung

    2013-01-01

    The current study proposes a model of the cardiovascular system that couples heart cell mechanics with arterial hemodynamics to examine the physiological role of arterial blood pressure (BP) in left ventricular hypertrophy (LVH). We developed a comprehensive multiphysics and multiscale cardiovascular model of the cardiovascular system that simulates physiological events, from membrane excitation and the contraction of a cardiac cell to heart mechanics and arterial blood hemodynamics. Using this model, we delineated the relationship between arterial BP or pulse wave velocity and LVH. Computed results were compared with existing clinical and experimental observations. To investigate the relationship between arterial hemodynamics and LVH, we performed a parametric study based on arterial wall stiffness, which was obtained in the model. Peak cellular stress of the left ventricle and systolic blood pressure (SBP) in the brachial and central arteries also increased; however, further increases were limited for higher arterial stiffness values. Interestingly, when we doubled the value of arterial stiffness from the baseline value, the percentage increase of SBP in the central artery was about 6.7% whereas that of the brachial artery was about 3.4%. It is suggested that SBP in the central artery is more critical for predicting LVH as compared with other blood pressure measurements. PMID:23960442

  17. An integrative model of the cardiovascular system coupling heart cellular mechanics with arterial network hemodynamics.

    Science.gov (United States)

    Kim, Young-Tae; Lee, Jeong Sang; Youn, Chan-Hyun; Choi, Jae-Sung; Shim, Eun Bo

    2013-08-01

    The current study proposes a model of the cardiovascular system that couples heart cell mechanics with arterial hemodynamics to examine the physiological role of arterial blood pressure (BP) in left ventricular hypertrophy (LVH). We developed a comprehensive multiphysics and multiscale cardiovascular model of the cardiovascular system that simulates physiological events, from membrane excitation and the contraction of a cardiac cell to heart mechanics and arterial blood hemodynamics. Using this model, we delineated the relationship between arterial BP or pulse wave velocity and LVH. Computed results were compared with existing clinical and experimental observations. To investigate the relationship between arterial hemodynamics and LVH, we performed a parametric study based on arterial wall stiffness, which was obtained in the model. Peak cellular stress of the left ventricle and systolic blood pressure (SBP) in the brachial and central arteries also increased; however, further increases were limited for higher arterial stiffness values. Interestingly, when we doubled the value of arterial stiffness from the baseline value, the percentage increase of SBP in the central artery was about 6.7% whereas that of the brachial artery was about 3.4%. It is suggested that SBP in the central artery is more critical for predicting LVH as compared with other blood pressure measurements.

  18. Experimental measurements and finite element analysis of the coupled vibrational characteristics of piezoelectric shells.

    Science.gov (United States)

    Huang, Yu-Hsi; Ma, Chien-Ching

    2012-04-01

    Piezoelectric plates can provide low-frequency transverse vibrational displacements and high-frequency planar vibrational displacements, which are usually uncoupled. However, piezoelectric shells can induce three-dimensional coupled vibrational displacements over a large frequency range. In this study, three-dimensional coupled vibrational characteristics of piezoelectric shells with free boundary conditions are investigated using three different experimental methods and finite element numerical modeling. For the experimental measurements, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) is used to obtain resonant frequencies and radial, lateral, and angular mode shapes. This optical technique utilizes a real-time, full-field, non-contact optical system that measures both the natural frequency and corresponding vibration mode shape simultaneously. The second experimental technique used, laser Doppler vibrometry (LDV), is a pointwise displacement measurement method that determines the resonant frequencies of the piezoelectric shell. An impedance analyzer is also used to determine the resonant frequencies of the piezoelectric shell. The experimental results of the resonant frequencies and mode shapes for the piezoelectric shell are verified with a numerical finite element model. Excellent agreement between the experimental and numerical results is found for the three-dimensional coupled vibrational characteristics of the piezoelectric shell. It is noted in this study that there is no coupled phenomenon at low frequencies over which radial modes dominate. However, three-dimensional coupled vibrational modes do occur at high resonant frequencies over which lateral or angular modes dominate.

  19. Comparison Between Numerically Simulated and Experimentally Measured Flowfield Quantities Behind a Pulsejet

    Science.gov (United States)

    Geng, Tao; Paxson, Daniel E.; Zheng, Fei; Kuznetsov, Andrey V.; Roberts, William L.

    2008-01-01

    Pulsed combustion is receiving renewed interest as a potential route to higher performance in air breathing propulsion systems. Pulsejets offer a simple experimental device with which to study unsteady combustion phenomena and validate simulations. Previous computational fluid dynamic (CFD) simulation work focused primarily on the pulsejet combustion and exhaust processes. This paper describes a new inlet sub-model which simulates the fluidic and mechanical operation of a valved pulsejet head. The governing equations for this sub-model are described. Sub-model validation is provided through comparisons of simulated and experimentally measured reed valve motion, and time averaged inlet mass flow rate. The updated pulsejet simulation, with the inlet sub-model implemented, is validated through comparison with experimentally measured combustion chamber pressure, inlet mass flow rate, operational frequency, and thrust. Additionally, the simulated pulsejet exhaust flowfield, which is dominated by a starting vortex ring, is compared with particle imaging velocimetry (PIV) measurements on the bases of velocity, vorticity, and vortex location. The results show good agreement between simulated and experimental data. The inlet sub-model is shown to be critical for the successful modeling of pulsejet operation. This sub-model correctly predicts both the inlet mass flow rate and its phase relationship with the combustion chamber pressure. As a result, the predicted pulsejet thrust agrees very well with experimental data.

  20. Experimental measurements of subsoil–structure interaction and 3D numerical models

    Directory of Open Access Journals (Sweden)

    Jana Labudkova

    2016-03-01

    Full Text Available Use of combination of experimental measurements, tests in situ and numerical modelling is optimal approach to obtain reliable results of subsoil–structure interaction. Input data for numerical analyses were obtained by experimental loading tests of three different types of concrete slabs. Loading was performed out using experimental equipment. The unique experimental equipment was constructed in the area of Faculty of Civil Engineering, VŠB-TU Ostrava. Analyses of interaction of reinforced concrete slabs with subsoil were solved by application of inhomogeneous half-space. The main focus was to verify the aptness of application of inhomogeneous half-space in relation to the slab deformations in comparison of different types of reinforcements of concrete slab.

  1. Experimental validation of error in temperature measurements in thin walled ductile iron castings

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2007-01-01

    An experimental analysis has been performed to validate the measurement error of cooling curves measured in thin walled ductile cast iron. Specially designed thermocouples with Ø0.2 mm thermocouple wire in Ø1.6 mm ceramic tube was used for the experiments. Temperatures were measured in plates...... to a level about 20C lower than the actual temperature in the casting. Factors affecting the measurement error (oxide layer on the thermocouple wire, penetration into the ceramic tube and variation in placement of thermocouple) are discussed. Finally, it is shown how useful cooling curve may be obtained...

  2. Analysis of the hemostatic potential of modern topical sealants on arterial and venous anastomoses: an experimental porcine study.

    Science.gov (United States)

    Fonouni, Hamidreza; Kashfi, Arash; Majlesara, Ali; Stahlheber, Oliver; Konstantinidis, Lukas; Kraus, Thomas W; Mehrabi, Arianeb; Oweira, Hani

    2017-09-01

    One of the widely accepted adjunctive agents in the variety of surgical modalities are sealants. Our study aim was to compare four commonly used modern sealants in a standardized experimental setting to assess their feasibility, and hemostatic efficacy in vascular anastomosis. Forty landrace pigs (weight: 24.7 ± 3.8 kg) were randomized into the control (n = 8) and four sealant groups; TachoSil® (n = 8), Tissucol Duo® (n = 8), Coseal® (n = 8), and FloSeal® (n = 8). After doing a portal vein end-to-end anastomosis as well as stitches of aortic incision, the sealants were applied on anastomotic site. The control group was left intact. In portal vein anastomosis, the sealants led to a complete hemostasis significantly better than control group. The mean of blood loss was also significantly reduced. In successful subgroups, there was a difference in the mean-time to reach complete hemostasis ranging from 15 s in Coseal® to 76 s in FloSeal® group (p  sealants led to a complete hemostasis. The mean blood loss was significantly reduced in sealants groups as well. The four sealants are effective in reducing the suture-hole bleeding in portal vein anastomosis. However, the hemostatic potential is heterogeneous among sealants. This means that "one-size-fits-all" approach is not appropriate for application of sealants in diversity of vascular surgery and it should be based on the type and the severity of injury and the structure of tissue. Comparison of hemostasis efficacy of four modern sealants (TachoSil®, Tissucol Duo®, Coseal®, and FloSeal®) in vascular anastomosis in porcine model. The figures below show the total blood loss (g) in the control and sealant groups after aortotomy (left) and portal vein anastomosis (right). The mean of blood loss decreased significantly by the usage of sealants in both experiment groups as compared to control group (*: p sealant groups vs. control group). 1. The right column shows the mean of

  3. COMPARISON OF EXPERIMENTAL-DESIGNS COMBINING PROCESS AND MIXTURE VARIABLES .2. DESIGN EVALUATION ON MEASURED DATA

    NARCIS (Netherlands)

    DUINEVELD, CAA; SMILDE, AK; DOORNBOS, DA

    The construction of a small experimental design for a combination of process and mixture variables is a problem which has not been solved completely by now. In a previous paper we evaluated some designs with theoretical measures. This second paper evaluates the capabilities of the best of these

  4. COMPARISON OF EXPERIMENTAL-DESIGNS COMBINING PROCESS AND MIXTURE VARIABLES .2. DESIGN EVALUATION ON MEASURED DATA

    NARCIS (Netherlands)

    DUINEVELD, C. A. A.; Smilde, A. K.; Doornbos, D. A.

    1993-01-01

    The construction of a small experimental design for a combination of process and mixture variables is a problem which has not been solved completely by now. In a previous paper we evaluated some designs with theoretical measures. This second paper evaluates the capabilities of the best of these

  5. Accuracy of measurement of acoustic rhinometry applied to small experimental animals

    DEFF Research Database (Denmark)

    Kaise, Toshihiko; Ukai, Kotara; Pedersen, Ole Finn

    1999-01-01

    -sectional areas as a function of the distance from the nostril. We modified the equipment used on humans to assess dimensions of nasal airway geometry of small experimental animals. The purpose of this study was to investigate the accuracy of measurement of the modified acoustic rhinometry applied to small...

  6. Experimentally Measured Susceptibility to Peer Influence and Adolescent Sexual Behavior Trajectories: A Preliminary Study

    Science.gov (United States)

    Choukas-Bradley, Sophia; Giletta, Matteo; Widman, Laura; Cohen, Geoffrey L.; Prinstein, Mitchell J.

    2014-01-01

    A performance-based measure of peer influence susceptibility was examined as a moderator of the longitudinal association between peer norms and trajectories of adolescents' number of sexual intercourse partners. Seventy-one 9th grade adolescents (52% female) participated in an experimental "chat room" paradigm involving…

  7. Experimentally measured susceptibility to peer influence and adolescent sexual behavior trajectories : A preliminary study

    NARCIS (Netherlands)

    Choukas-Bradley, S.; Giletta, M.; Widman, L.; Cohen, G.L.; Prinstein, M.J.

    2014-01-01

    A performance-based measure of peer influence susceptibility was examined as a moderator of the longitudinal association between peer norms and trajectories of adolescents' number of sexual intercourse partners. Seventy-one 9th grade adolescents (52% female) participated in an experimental "chat

  8. Experimental Measurements of the Density of States for a Granular Crystal

    Science.gov (United States)

    Bertrand, Thibault; O'Hern, Corey S.; Shattuck, Mark D.

    The vibrational density of states relates the structure and dynamics of materials. Several previous experimental studies have measured the density of states in colloidal glasses and identified an abundance of low energy collective excitations that give rise to anomalous behavior for the shear modulus. However, very few measurements of the density of states have been performed for driven granular materials. We report experimental investigations of the vibrational density of states of a quasi-2D uniformly heated granular crystal below the jamming density. We find that over the range of packing fractions we consider particles do not escape from their cages over the timescale of the measurements. We measure the density of states in two ways: from the power spectrum of the velocity autocorrelation function and the eigenvalues of the covariance matrix of particle displacements. We compare the experimental measurements of the density of states to results obtained from similar measurements on 2D and quasi-2D hard sphere simulations. W. M. Keck Foundation Science and Engineering Grant.

  9. Validation of brachial artery pressure reconstruction from finger arterial pressure

    NARCIS (Netherlands)

    Guelen, Ilja; Westerhof, Berend E.; van der Sar, Gertrude L.; van Montfrans, Gert A.; Kiemeneij, Ferdinand; Wesseling, Karel H.; Bos, Willem Jan W.

    2008-01-01

    Objective Measurement of finger artery pressure with Finapres offers noninvasive continuous blood pressure, which, however, differs from brachial artery pressure. Generalized waveform filtering and level correction may convert the finger artery pressure waveform to a brachial waveform. An upper-arm

  10. Authentication of Radial Versus Femoral Arterial Pressure Waveform-Derived Cardiac Output With Transesophageal Echocardiography-Derived Cardiac Output Measurements in Patients Undergoing On-Pump Coronary Bypass Surgery.

    Science.gov (United States)

    Maddali, Madan Mohan; Waje, Niranjan Dilip; Sathiya, Panchatcharam Murthi

    2017-08-01

    The aim of this study was to ascertain if arterial waveform-derived cardiac output measurements from radial and femoral cannulation sites were reliable as compared with transesophageal echocardiography (TEE)-derived cardiac output (CO) values, and which of the CO measurements derived from radial and the femoral arterial pressure waveforms closely tracked simultaneously measured TEE-derived CO values. This study also aimed to ascertain if cardiopulmonary bypass (CPB) would impact the accuracy of arterial pressure-derived CO values from either of the 2 sites. A prospective observational study. Tertiary care cardiac center. Cardiac surgical patients undergoing on-pump primary coronary artery bypass surgery. Waveform-derived CO monitoring through radial and femoral artery cannulation using a FloTrac/Vigileo system. Twenty-seven consecutive cardiac surgical patients undergoing on-pump primary coronary artery bypass surgery were included in the study. Cardiac output was measured sequentially by the arterial pressure waveform analysis method from radial and femoral arterial sites and compared with simultaneously measured TEE-derived CO. Cardiac output data were obtained in triplicate at 6 predefined time intervals: before and after sternotomy, 5, 15, and 30 minutes after separation from CPB and prior to shifting the patient out of the operating room. The overall bias of the study was 0.11 and 0.27, the percentage error was 19.31 and 18.45, respectively, for radial and femoral arterial waveform-derived CO values as compared with TEE-derived CO measurements. The overall precision as compared with the TEE-derived CO values was 16.94 and 15.95 for the radial and femoral cannulation sites, respectively. The bias calculated by the Bland-Altman method suggested that CO measurements from the radial arterial site were in closer agreement with TEE-derived CO values at all time periods, and the relation was not affected by CPB. However, percentage error and precision calculations

  11. Development of the Neuron Assessment for Measuring Biology Students’ Use of Experimental Design Concepts and Representations

    Science.gov (United States)

    Dasgupta, Annwesa P.; Anderson, Trevor R.; Pelaez, Nancy J.

    2016-01-01

    Researchers, instructors, and funding bodies in biology education are unanimous about the importance of developing students’ competence in experimental design. Despite this, only limited measures are available for assessing such competence development, especially in the areas of molecular and cellular biology. Also, existing assessments do not measure how well students use standard symbolism to visualize biological experiments. We propose an assessment-design process that 1) provides background knowledge and questions for developers of new “experimentation assessments,” 2) elicits practices of representing experiments with conventional symbol systems, 3) determines how well the assessment reveals expert knowledge, and 4) determines how well the instrument exposes student knowledge and difficulties. To illustrate this process, we developed the Neuron Assessment and coded responses from a scientist and four undergraduate students using the Rubric for Experimental Design and the Concept-Reasoning Mode of representation (CRM) model. Some students demonstrated sound knowledge of concepts and representations. Other students demonstrated difficulty with depicting treatment and control group data or variability in experimental outcomes. Our process, which incorporates an authentic research situation that discriminates levels of visualization and experimentation abilities, shows potential for informing assessment design in other disciplines. PMID:27146159

  12. Measuring and Advancing Experimental Design Ability in an Introductory Course without Altering Existing Lab Curriculum.

    Science.gov (United States)

    Shanks, Ryan A; Robertson, Chuck L; Haygood, Christian S; Herdliksa, Anna M; Herdliska, Heather R; Lloyd, Steven A

    2017-01-01

    Introductory biology courses provide an important opportunity to prepare students for future courses, yet existing cookbook labs, although important in their own way, fail to provide many of the advantages of semester-long research experiences. Engaging, authentic research experiences aid biology students in meeting many learning goals. Therefore, overlaying a research experience onto the existing lab structure allows faculty to overcome barriers involving curricular change. Here we propose a working model for this overlay design in an introductory biology course and detail a means to conduct this lab with minimal increases in student and faculty workloads. Furthermore, we conducted exploratory factor analysis of the Experimental Design Ability Test (EDAT) and uncovered two latent factors which provide valid means to assess this overlay model's ability to increase advanced experimental design abilities. In a pre-test/post-test design, we demonstrate significant increases in both basic and advanced experimental design abilities in an experimental and comparison group. We measured significantly higher gains in advanced experimental design understanding in students in the experimental group. We believe this overlay model and EDAT factor analysis contribute a novel means to conduct and assess the effectiveness of authentic research experiences in an introductory course without major changes to the course curriculum and with minimal increases in faculty and student workloads.

  13. Measuring and Advancing Experimental Design Ability in an Introductory Course without Altering Existing Lab Curriculum

    Directory of Open Access Journals (Sweden)

    Ryan A. Shanks

    2017-05-01

    Full Text Available Introductory biology courses provide an important opportunity to prepare students for future courses, yet existing cookbook labs, although important in their own way, fail to provide many of the advantages of semester-long research experiences. Engaging, authentic research experiences aid biology students in meeting many learning goals. Therefore, overlaying a research experience onto the existing lab structure allows faculty to overcome barriers involving curricular change. Here we propose a working model for this overlay design in an introductory biology course and detail a means to conduct this lab with minimal increases in student and faculty workloads. Furthermore, we conducted exploratory factor analysis of the Experimental Design Ability Test (EDAT and uncovered two latent factors which provide valid means to assess this overlay model’s ability to increase advanced experimental design abilities. In a pre-test/post-test design, we demonstrate significant increases in both basic and advanced experimental design abilities in an experimental and comparison group. We measured significantly higher gains in advanced experimental design understanding in students in the experimental group. We believe this overlay model and EDAT factor analysis contribute a novel means to conduct and assess the effectiveness of authentic research experiences in an introductory course without major changes to the course curriculum and with minimal increases in faculty and student workloads.

  14. 1D.09: APPLICABILITY OF MEASUREMENT OF RENAL PERFUSION USING 1.5 TESLA MRI ARTERIAL SPIN LABELLING.

    Science.gov (United States)

    Kistner, I; Ott, C; Jumar, A; Friedrich, S; Grosso, R; Siegl, C; Schmieder, R E; Janka, R

    2015-06-01

    Renal perfusion is a key parameter of kidney function and the decrement of renal perfusion is a marker of target organ damage caused by hypertension. Detecting these changes in renal perfusion could help to manage antihypertensive therapy and evaluate patients[Combining Acute Accent] prognosis. Measurement of renal perfusion by MRI arterial spin labelling (ASL) is a non-invasive and non-time-consuming method without the need to inject any contrast agent. This study examined reproducibility of renal perfusion measured by 1.5 Tesla MRI. Renal perfusion was measured by ASL technique using an 1.5 Tesla MRI scanner. Subjects were scanned 3 times at two different days in an interval of two weeks to assess the test-retest reproducibility. Renal perfusion was automatically calculated for the cortex and medulla of the kidney by dedicated software. 14 patients were included with mean age 48.9 ± 12.7 and mean office blood pressure 132 ± 16/82 ± 10mmHg and estimated glomerular filtration rate> 60 ml/min/1.73m. The change of the mean total, cortical and medullary renal perfusion from the first examination to the second examination was 0.37 ± 13/0.62 ± 18/0.00 ± 12 ml/min/100 g kidney weight (p = 0.915/p = 0.898/p = 0.998), respectively. There was also no significant difference between the three renal perfusion measurements at one time point. For clinical trials these data indicate that to detect a 5% (10%) difference of cortical renal perfusion due to an intervention (vs placebo) only 38 (14) patients are required in face of the observed standard deviation for the change in renal perfusion. The inter and intra-session reproducibility of cortical renal perfusion assessed by MRI ASL 1.5 Tesla is excellent and small study cohorts can be used for examination of renal perfusion.

  15. Comparison of transthoracic electrical bioimpedance cardiac output measurement with thermodilution method in post coronary artery bypass graft patients

    Directory of Open Access Journals (Sweden)

    Sharma Vikas

    2011-01-01

    Full Text Available Transthoracic electrical bioimpedance (TEB has been proposed as a non-invasive, continuous, and cost-effective method of cardiac output (CO measurement. In this prospective, non-randomized, clinical study, we measured CO with NICOMON (Larsen and Toubro Ltd., Mysore, India and compared it with thermodilution (TD method in patients after off-pump coronary artery bypass (OPCAB graft surgery. We also evaluated the effect of ventilation (mechanical and spontaneous on the measurement of CO by the two methods. Forty-six post-OPCAB patients were studied at five predefined time points during controlled ventilation and at five time points when breathing spontaneously. A total of 230 data pairs of CO were obtained. During controlled ventilation, TD CO values ranged from 2.29 to 6.74 L/min (mean 4.45 ± 0.85 L/min, while TEB CO values ranged from 1.70 to 6.90 L/min (mean 4.43 ± 0.94 L/min. The average correlation (r was 0.548 (P = 0.0002, accompanied by a bias of 0.015 L/min and precision of 0.859 L/min. In spontaneously breathing patients, TD CO values ranged from 2.66 to 6.92 L/min (mean 4.66 ± 0.76 L/min, while TEB CO values ranged from 3.08 to 6.90 L/min (mean 4.72 ± 0.82 L/min. Their average correlation was relatively poor (r = 0.469, P= 0.002, accompanied by a bias of −0.059 L/min and precision of 0.818 L/min. The overall percent errors between TD CO and TEB CO were 19.3% (during controlled ventilation and 17.4% (during spontaneous breathing, respectively. To conclude, a fair correlation was found between TD CO and TEB CO measurements among post-OPCAB patients during controlled ventilation. However, the correlation was weak in spontaneously breathing patients.

  16. Comparison of transthoracic electrical bioimpedance cardiac output measurement with thermodilution method in post coronary artery bypass graft patients.

    Science.gov (United States)

    Sharma, Vikas; Singh, Ajmer; Kansara, Bhuvnesh; Karlekar, Anil

    2011-01-01

    Transthoracic electrical bioimpedance (TEB) has been proposed as a non-invasive, continuous, and cost-effective method of cardiac output (CO) measurement. In this prospective, non-randomized, clinical study, we measured CO with NICOMON (Larsen and Toubro Ltd., Mysore, India) and compared it with thermodilution (TD) method in patients after off-pump coronary artery bypass (OPCAB) graft surgery. We also evaluated the effect of ventilation (mechanical and spontaneous) on the measurement of CO by the two methods. Forty-six post-OPCAB patients were studied at five predefined time points during controlled ventilation and at five time points when breathing spontaneously. A total of 230 data pairs of CO were obtained. During controlled ventilation, TD CO values ranged from 2.29 to 6.74 L/min (mean 4.45 ± 0.85 L/min), while TEB CO values ranged from 1.70 to 6.90 L/min (mean 4.43 ± 0.94 L/min). The average correlation (r) was 0.548 (P = 0.0002), accompanied by a bias of 0.015 L/min and precision of 0.859 L/min. In spontaneously breathing patients, TD CO values ranged from 2.66 to 6.92 L/min (mean 4.66 ± 0.76 L/min), while TEB CO values ranged from 3.08 to 6.90 L/min (mean 4.72 ± 0.82 L/min). Their average correlation was relatively poor (r = 0.469, P= 0.002), accompanied by a bias of -0.059 L/min and precision of 0.818 L/min. The overall percent errors between TD CO and TEB CO were 19.3% (during controlled ventilation) and 17.4% (during spontaneous breathing), respectively. To conclude, a fair correlation was found between TD CO and TEB CO measurements among post-OPCAB patients during controlled ventilation. However, the correlation was weak in spontaneously breathing patients.

  17. Thickness optimization of Sn–Pb alloys for experimentally measuring mass attenuation coefficients

    Directory of Open Access Journals (Sweden)

    Taranjot Kaur

    2017-03-01

    Full Text Available An attempt has been made to experimentally investigate the optimum thickness in order to measure mass attenuation coefficients for some Sn–Pb alloy systems at incident photon energies 122, 511 and 662keV. The Sn–Pb alloys were synthesized with different compositions and different thicknesses using melt-quench technique and cast iron mould. The physical parameters such as mass, thickness, density have been measured for all the prepared alloys. Further, the transmitted photon spectra of Cs-137, Co-57 and Na-22 radioactive isotopes were recorded using GAMMARAD5 (scintillator detector of dimensions 76mm×76mm with and without inserting different alloy samples between the radioactive isotopes and detector. The experimental results so obtained were compared with the theoretical ones of WinXCom and optimum thickness for measuring mass attenuation coefficients for the selected alloys has been recommended.

  18. Experimental Measurements of e-Cloud Mitigation Using Clearing Electrodes in the DAФNE Collider

    CERN Document Server

    Alesini, D; Gallo, A; Guiducci, S; Milardi, C; Zobov, M; De Santis, S; Demma, Theo; Raimondi, P

    2012-01-01

    Recently the DAФNE electron-positron collider has started delivering luminosity to the KLOE-2 experiment. For this run special metallic electrodes were installed in all the dipole and wiggler magnets of the positron ring to cope with the effects induced by the e-cloud formation. Experimental measurements have shown an impressive effectiveness of these devices in mitigating the e-cloud impact on the positron beam dynamics. The electrodes allow reducing the vertical beam size and the growth rate of transverse instabilities as well as the tune shifts induced by the electron cloud itself. Moreover frequency shift measurements of the vacuum chamber resonances, switching on and off the electrodes, indicate an evident reduction of the electron cloud density. This paper reports and analyses all the experimental observations and measurements done to suppress the e-cloud induced effects by using metallic electrodes.

  19. 3D strain map of axially loaded mouse tibia: a numerical analysis validated by experimental measurements.

    Science.gov (United States)

    Stadelmann, Vincent A; Hocke, Jean; Verhelle, Jensen; Forster, Vincent; Merlini, Francesco; Terrier, Alexandre; Pioletti, Dominique P

    2009-02-01

    A combined experimental/numerical study was performed to calculate the 3D octahedral shear strain map in a mouse tibia loaded axially. This study is motivated by the fact that the bone remodelling analysis, in this in vivo mouse model should be performed at the zone of highest mechanical stimulus to maximise the measured effects. Accordingly, it is proposed that quantification of bone remodelling should be performed at the tibial crest and at the distal diaphysis. The numerical model could also be used to furnish a more subtle analysis as a precise correlation between local strain and local biological response can be obtained with the experimentally validated numerical model.

  20. Noninvasive measurement of relative cerebral blood glow using arterial spin labeling techniques: Physical basics and clinical applications; Nichtinvasive Messung des relativen zerebralen Blutflusses mit der MR-Blutbolusmarkierungstechnik (arterial-spin-labeling): Physikalische Grundlagen und klinische Anwendungen

    Energy Technology Data Exchange (ETDEWEB)

    Weber, M.A. [Abteilung Onkologische Diagnostik und Therapie, Deutsches Krebsforschungszentrum (dkfz) Heidelberg (Germany); Abteilung Onkologische Diagnostik und Therapie, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, 69120, Heidelberg (Germany); Kroll, A. [Abteilung Biophysik und Medizinische Strahlenphysik, Deutsches Krebsforschungszentrum (dkfz) Heidelberg (Germany); Deutsches Krebsforschungszentrum (dkfz), Abteilung Medizinische Physik in der Radiologie (E020), Im Neuenheimer Feld 280, 69120, Heidelberg (Germany); Guenther, M. [Abteilung Biophysik und Medizinische Strahlenphysik, Deutsches Krebsforschungszentrum (dkfz) Heidelberg (Germany); Advanced MRI Technologies, Sebastopol, CA (United States); Delorme, S.; Debus, J.; Giesel, F.L.; Essig, M.; Kauczor, H.U. [Abteilung Onkologische Diagnostik und Therapie, Deutsches Krebsforschungszentrum (dkfz) Heidelberg (Germany); Schad, L.R. [Abteilung Biophysik und Medizinische Strahlenphysik, Deutsches Krebsforschungszentrum (dkfz) Heidelberg (Germany)

    2004-02-01

    Knowledge of tumor blood flow is important for diagnosis and follow-up of brain tumors after therapy, especially to discriminate necrosis from tumor recurrence after radiation or chemotherapy. Meanwhile, perfusion and diffusion MRI, besides MR-angiography, are state of the art in stroke imaging. Until now, perfusion imaging was mostly performed using the first-pass dynamic susceptibility-weighted contrast-enhanced (DSC) MRI. The MRI-based arterial spin labeling technique (ASL) is a novel approach for measuring relative cerebral blood flow (rCBF) without using extrinsic contrast agents, by labeling spins of flowing arterial blood as intrinsic contrast agent. This article describes physical basics of ASL and shows clinical examples in neuroimaging such as in meningeoma, glioblastoma, oligodendroglioma, and cerebral ischemia, using the Q2TIPS ASL technique. Gray matter is clearly visible, while the observed white matter signal obtained by Q2TIPS is only slightly higher than background noise. Venous blood causes artefacts in the sagittal sinus and other large superficial veins in the subarachnoid space. Meningeoma and glioblastoma show elevated rCBF, whereas oligodendroglioma and cerebral ischemia have reduced rCBF values. Arterial-spin-labeling techniques are noninvasive tools for measuring rCBF within 5 min, using a standard MRI scanner. (orig.) [German] Die Bestimmung des Blutflusses innerhalb eines Tumors ist fuer den klinischen Onkologen zur Differenzialdiagnostik von Hirntumoren und zur Verlaufskontrolle nach Therapie von grossem Interesse, insbesondere zur Beurteilung von Nekrose oder Rezidiv nach Chemo- oder Strahlenbehandlung. In der Schlaganfallmedizin gehoert mittlerweile die Bestimmung des Blutflusses und des Blutvolumens neben MR-Diffusionsbildgebung und MR-Angiographie zur Standarddiagnostik. Die derzeit mit der MRT durchgefuehrten Perfusionsmessungen basieren hauptsaechlich auf der kontrastmittelverstaerkten T2{sup *}-Dynamik. Mit der

  1. Theoretical analysis and experimental measurement for resonant vibration of piezoceramic circular plates.

    Science.gov (United States)

    Huang, Chi-Hung; Lin, Yu-Chih; Ma, Chien-Ching

    2004-01-01

    Based on the electroelastic theory for piezoelectric plates, the vibration characteristics of piezoceramic disks with free-boundary conditions are investigated in this work by theoretical analysis, numerical simulation, and experimental measurement. The resonance of thin piezoceramic disks is classified into three types of vibration modes: transverse, tangential, and radial extensional modes. All of these modes are investigated in detail. Two optical techniques, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) and laser Doppler vibrometer (LDV), are used to validate the theoretical analysis. Because the clear fringe patterns are shown only at resonant frequencies, both the resonant frequencies and the corresponding mode shapes are obtained experimentally at the same time by the proposed AF-ESPI method. Good quality of the interferometric fringe patterns for both the transverse and extensional vibration mode shapes are demonstrated. The resonant frequencies of the piezoceramic disk also are measured by the conventional impedance analysis. Both theoretical and experimental results indicate that the transverse and tangential vibration modes cannot be measured by the impedance analysis, and only the resonant frequencies of extensional vibration modes can be obtained. Numerical calculations based on the finite element method also are performed, and the results are compared with the theoretical analysis and experimental measurements. It is shown that the finite element method (FEM) calculations and the experimental results agree fairly well for the resonant frequencies and mode shapes. The resonant frequencies and mode shapes predicted by theoretical analysis and calculated by finite element method are in good agreement, and the difference of resonant frequencies for both results with the thickness-to-diameter (h/D) ratios, ranging from 0.01 to 0.1, are presented.

  2. Relationship between serum levels of triglycerides and vascular inflammation, measured as COX-2, in arteries from diabetic patients: a translational study

    Science.gov (United States)

    2013-01-01

    Background Inflammation is a common feature in the majority of cardiovascular disease, including Diabetes Mellitus (DM). Levels of pro-inflammatory markers have been found in increasing levels in serum from diabetic patients (DP). Moreover, levels of Cyclooxygenase-2 (COX-2) are increased in coronary arteries from DP. Methods Through a cross-sectional design, patients who underwent CABG were recruited. Vascular smooth muscle cells (VSMC) were cultured and COX-2 was measured by western blot. Biochemical and clinical data were collected from the medical record and by blood testing. COX-2 expression was analyzed in internal mammary artery cross-sections by confocal microscopy. Eventually, PGI2 and PGE2 were assessed from VSMC conditioned media by ELISA. Results Only a high glucose concentration, but a physiological concentration of triglycerides exposure of cultured human VSMC derived from non-diabetic patients increased COX-2 expression .Diabetic patients showed increasing serum levels of glucose, Hb1ac and triglycerides. The bivariate analysis of the variables showed that triglycerides was positively correlated with the expression of COX-2 in internal mammary arteries from patients (r2 = 0.214, P < 0.04). Conclusions We conclude that is not the glucose blood levels but the triglicerydes leves what increases the expression of COX-2 in arteries from DP. PMID:23642086

  3. Experimental Tooling for Contact Stress Measurement in Bulk Metal Forming Processes

    Science.gov (United States)

    Vilotić, Dragiša; Plančak, Miroslav

    2011-01-01

    Knowledge of contact stresses in metal forming operations is essential not only for optimal die design, but also for theoretical and numerical analysis of the metal forming processes. Determination of contact stresses can be performed theoretically and experimentally. This paper presents a tool construction with built-in pin-load cells for experimental determination of contact stresses and friction coefficient at upsetting of prismatic specimen with cylindrical dies. This construction allows measurement of contact stresses in any point of the contact surface of specimen, due to adjustable location of pin-load cells. The adjustments are performed by turning cylindrical dies around its own axis in combination with the change of axial position of the specimen. Experimental determination of contact stresses in upsetting of Ck35 prismatic specimens using cylindrical tools was performed at the Laboratory for technology of plasticity, FTN Novi Sad.

  4. Depression and anxiety in patients with coronary artery disease, measured by means of self-report measures and clinician-rated instrument.

    Science.gov (United States)

    Moryś, Joanna M; Bellwon, Jerzy; Adamczyk, Katarzyna; Gruchała, Marcin

    2016-01-01

    The presence of depression symptomatology significantly deteriorates the prognosis for the patient. There are many instruments developed to measure depression and anxiety in clinical trials; however, the suitability of the specific scale for screening these disorders in cardiovascular patients is debatable. The aim of current study is to verify which of the major assessment instruments is the most relevant for the screening evaluation of depression and anxiety in patients with cardiovascular system diseases. The sample studied consisted of 120 patients with stable coronary artery disease (CAD). They did not display serious psychiatric or somatic disorders. To assess depressive and anxiety symptoms we used self-reporting measures (BDI-II, HADS, SSAI/STAI, and PHQ), the results of which were compared to results obtained on the basis of a clinician-rating instrument (HRSD). We found that depressive symptoms assessed on the basis of HRSD, BDI-II, and PHQ-9 were equivalent in results, while the results obtained in HADS-D were significantly lower. Anxiety symptoms were found at approximate levels in HADS, SSAI, and GAD-7. The assessment of somatic symptoms in patients with CAD indicates that 87.5% of the subjects reported somatic symptoms of various intensity. Screening assessment of depression in patients with CAD gives different results depending on the tool used. We found that HADS significantly underestimates the percentage of patients with symptoms of depression in patients with CAD. Assessing anxiety symptoms with the aid of HADS gave outcomes close to the results gained by use of other tools.

  5. Arterial spin labeling for quantitative functional MRI.

    Science.gov (United States)

    Hernandez-Garcia, Luis

    2004-01-01

    BOLD effect imaging is very effective for detection and localization of brain activity, and is the dominant functional imaging technique in cognitive psychology. Despite its efficiency to detect and localize active site, the technique does not lend itself easily to quantifiable measurements. A growingly popular alternative is the use of arterial spin labeling (ASL) to obtain perfusion maps as the indicator of cerebral activation. In this paper, the principles and challenges of arterial spin labeling are discussed and the development of a new fast, two-coil pseudo-continuous labeling scheme is presented. The new scheme permits collection of a multi-slice subtraction pair in less than three seconds, depending on the subject's arterial transit times. The theoretical basis of the technique, as well as a model for quantification of perfusion from the ASL data, are presented. Experimental data from functional imaging experiments were collected to demonstrate the technique and its characteristics.

  6. Establishment of Experimental Equipment for Training of Professionals in the Nuclear Radiation Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, S. K.; Seo, K. W.; Joo, Y. C.; Kim, I. C.; Woo, C. K.; Yoo, B. H. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-09-15

    The main purpose of this project is to establish experimental equipment for training of professionals and students in the field of radiation measurement, and settle the foundation for the advanced education system and program. The priority for the experimental equipment had been deduced by reviewing of the Nuclear Training and Education Center of KAERI and other country's training courses. Equipment for training of radiation professionals are High-Purity Germanium spectroscopic systems, alpha analyzers, and hand-held gamma/neutron inspector systems. For the basic experiments, electric personal dosimeters and a reader, radiation survey meters, and various alpha, beta and gamma radiation isotopes have been equipped. Some old or disused equipment and devices were disposed and re-arranged, and a new experiment lab had been settled for gamma spectroscopy. Along with the preparation of equipment, 14 experimental modules have been selected for practical and essential experiments training to professionals from industries, universities and research organizations. Among the modules, 7 important experiment notes had been prepared in Korea and also in English. As a consequence, these advanced radiation experimental setting would be a basis to cooperate with IAEA or other countries for international training courses. These activities would be a foundation for our contribution to the international nuclear society and for improving our nuclear competitiveness. The experimental equipment and application notes developed in this study will be used also by other training institutes and educational organizations through introducing and encouraging to use them to the nuclear society.

  7. Numerical and Experimental Calibration of a Calorimetric Sample Cell Dedicated to Nuclear Heating Measurements

    Science.gov (United States)

    Brun, J.; Reynard-Carette, C.; Lyoussi, A.; Merroun, O.; Carette, M.; Janulyte, A.; Zerega, Y.; Andre, J.; Bignan, G.; Chauvin, J.-P.; Fourmentel, D.; Gonnier, C.; Guimbal, P.; Malo, J.-Y.; Villard, J.-F.

    2012-12-01

    Online nuclear measurements inside experimental channels of material testing reactors (MTRs) are needed for experimental works (to design mock-ups) and for numerical works (input data) in order to better understanding complex phenomena occurring during the accelerated ageing of materials and the irradiation of nuclear fuels. In this paper, we focus only on one kind of measurements: nuclear heating performed by means of a radiometric calorimeter. The aims of numerical and experimental works are firstly to optimize the sensor response: in particular the sensitivity for new energy deposit ranges (new lower nuclear heating level in the reflector), and then to miniaturize and adapt this sensor for irradiation conditions in the Jules Horowitz Reactor (JHR). A calorimeter, developed previously by the CEA, is studied. It corresponds to a graphite differential calorimeter. It is used with a nonadiabatic mode called heat flow mode too. Experimental calibration of the sample cell is presented. In that case, energy deposit is simulated by Joule effect and the sample cell is inserted into a bath at a regulated temperature and controlled flow. The response of the sensor is discussed versus electrical power imposed for two flow rates. Numerical works show the influence of the gas conductivity and of specific dimensions on the cell sensitivity.

  8. Bioimpedance measurements in dentistry to detect inflammation: numerical modelling and experimental results.

    Science.gov (United States)

    Cosoli, G; Scalise, L; Tricarico, G; Russo, P; Cerri, G

    2017-06-01

    Bioimpedance measurements represent an advantageous method to evaluate the physio-pathological conditions of biological tissues and their use is spreading in different application fields, from the evaluation of body composition to the vital signs monitoring, passing through the individuation of cancer tissues and the detection of different substances (e.g. glucose measurements in people affected by diabetes). In fact, tissues electric properties vary with their conditions; for example, electrical conductivity increases when there is an inflammatory process, because of the presence of oedema, hyperaemia and infiltration. Inflammatory phenomena are frequent in dentistry, in diseases like periodontitis and peri-implantitis; however, at present the diagnosis is mainly done with the naked eye, by observing the gingiva redness and swelling. The aim of this work is to prove the feasibility of the inflammation detection by means of bioimpedance measurements. Both numerical simulations and preliminary experimental measurements provide significant outcomes in differentiating between healthy and inflamed tissues. Percentage differences in the impedance modulus equal to 4-20% (numerical simulations) and 35-56% (experimental measurements), respectively, depending on the considered conditions (e.g. electrodes characteristics and inflammation severity), were found. Such a measure could be integrated in electromedical devices designed, for example, for the therapy of peri-implantitis, in order to personalise the therapeutic dose in terms of intensity and duration and focusing it on the impaired area, minimising the effects on the surrounding tissues.

  9. 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

    thermal history of different points selected at the plaque surface, it is seen that during the cardiac cycle the temperature at a point located at l/lp = 0.7 can change between 0.5 and 0.1 degrees Celsius for the bending artery, while no significant variation is observed in the arterial bifurcation. Calculations performed for different values of inflammatory cell layer thickness dmp indicate the same behavior reported experimentally; that corresponds to an increase in the maximum temperature observed, which for the bending artery ranges from 0.6 to 2.0 degrees Celsius, for dmp = 25 and 100 micrometers, respectively. Conclusion The results indicate that direct temperature measurements should be taken (1 as close as possible to the plaque/lumen surface, as the calculations show a significant drop in temperature within 120 micrometers from the plaque surface; (2 in the presence of blood flow, temperature measurement should be performed in the downstream edge of the plaque, as it shows higher temperature independently of the arterial geometry; and (3 it is necessary to perform measurements at a sampling rate that is higher than the cardiac cycle; the measurement should be extended through several cardiac cycles, as variations of up to 0.7 degrees Celsius were observed at l/lp = 0.7 for the bending artery.

  10. A combined experimental with simulation approach to calibrated 3D strain measurement using shearography

    OpenAIRE

    Goto, D.T.; Groves, R.M.

    2010-01-01

    This paper is concerned with the development of a calibrated 3D shearography strain measurement instrument, calibrated iteratively, using a combined mechanical-optical model and specially designed test objects. The test objects are a cylinder loaded by internal pressure and a flat plate under axial load. Finite element models of the samples, combined with optical models of the shearography system, allow phase maps to be simulated for subsequent comparison with experimental phase maps from the...

  11. Experimental Aspects of In-Plane Displacement Measurement Using a Moire Fringe Technique.

    Science.gov (United States)

    1986-06-01

    AD-A174 048 EXPERIMENTAL ASPECTS OF IN-PLANE DISPLACEMENT 1 / 1’ MEASUREMENT USING A NOIRE F.. (U) AERONAUTICAL RESEARCH I LABS MELBOURNE (AUSTRALIA...solution poured rapidly over their central area. However, this technique resulted in streaking of the film coating. This problem was minimized by varying...defined when flash lighting was employed. The magnification of the image and rotational misalignment of the film mount, were adjusted with the aid of a

  12. Introduction of Nuclear Instrumentations and Radiation Measurements in Experimental Fast Reactor 「JOYO」

    OpenAIRE

    大戸 敏弘; 鈴木 惣十

    1992-01-01

    This report introduces the nuclear instrumentation system and major R&D (research and development) activities using radiation measurement techniques in Experimental Fast Reactor "JOYO". In the introduction of the nuclear instrumentation system, following items are described; (1)system function (2)roles as a reactor plant equipment (3)specifications and charactelistics of neutron detectors, (4)construction and layout of the system. For reactor dosimetry at various irradiation tests and surveil...

  13. Experimental Approaches for Measuring pKa's in RNA and DNA

    Science.gov (United States)

    Thaplyal, Pallavi; Bevilacqua, Philip C.

    2017-01-01

    RNA and DNA carry out diverse functions in biology including catalysis, splicing, gene regulation, and storage of genetic information. Interest has grown in understanding how nucleic acids perform such sophisticated functions given their limited molecular repertoire. RNA can fold into diverse shapes that often perturb pKa values and allow it to ionize appreciably under biological conditions, thereby extending its molecular diversity. The goal of this article is to enable experimental measurement of pKa's in RNA and DNA. A number of experimental methods for measuring pKa values in RNA and DNA have been developed over the last ten years, including RNA cleavage kinetics; UV-, fluorescence-, and NMR-detected pH titrations; and Raman crystallography. We begin with general considerations for choosing a pKa assay and then describe experimental conditions, advantages and disadvantages for these methods. Potential pitfalls in measuring a pKa are provided including the presence of apparent pKa's due to a kinetic pKa or coupled acid- and alkali-promoted RNA unfolding, as well as RNA degradation, precipitation of metal hydroxides and poor baselines. Use of multiple data fitting procedures and the study of appropriate mutants are described as ways to avoid some of these pitfalls. Application of these experimental methods to RNA and DNA will increase the number of nucleic acid pKa values in the literature, which should deepen insight into biology and provide benchmarks for calculations. Future directions for measuring pKa's in nucleic acids are discussed. PMID:25432750

  14. Measuring the relative productivity of multitasking to sole-tasking in household production: New experimental evidence

    OpenAIRE

    Foster, Gigi; Kalenkoski, Charlene

    2012-01-01

    We present a household production model that incorporates multitasking and results from a customized experiment designed to measure the individual-specific productivity parameters from this model. We observe these productivity parameters under alternative incentive scenarios, designed to mimic changes in the relative utility payoffs to the two tasks. Using information on demographic and other characteristics collected through an on-screen survey taken by our experimental participants, we exam...

  15. Relationship between hemodynamic changes of portal vein and hepatic artery measured by color Doppler ultrasound and FibroScan value in patients with liver cirrhosis

    Directory of Open Access Journals (Sweden)

    CHENG Xiaofei

    2014-11-01

    Full Text Available ObjectiveTo explore the relationship between hemodynamic changes of the portal vein and hepatic artery measured by color Doppler ultrasound and FibroScan value in patients with liver cirrhosis. MethodsA total of 192 patients with hepatitis B cirrhosis who were admitted to our hospital from March 2010 to December 2013, as well as 100 healthy persons, were recruited. The mean portal vein blood flow velocity (PVVmean, hepatic artery pulsatility index (HAPI, and hepatic artery resistance index (HARI were measured by color Doppler ultrasound. FibroScan was also carried out. All data were statistically analyzed using SPSS 13.0. Continuous data were expressed as mean±SD and compared between groups by t-test. ResultsThe HAPI, HARI, and FibroScan value of the patient group were 1.56±024, 0.73±0.05, and 25.38±7.73, respectively, significantly higher than those of the control group (1.36±0.14, 0.65±0.07, and 7.8±3.6 (P<0.05; the PVVmean of the patient group was 14.43±1.86, significantly lower than that of the control group (17.35±0.56 (P<0.05. FibroScan value was positively correlated with HAPI and HARI (r1=0.59, r2=0.66, P<0.001, but negatively correlated with PVVmean (r=-0.64, P<0.001. ConclusionThe liver stiffness assessed by FibroScan and the hemodynamic changes of the portal vein and hepatic artery measured by color Doppler ultrasound are vitally important for evaluating the severity of liver cirrhosis.

  16. Experimental measurement of time-dependent photon scatter for diffuse optical tomography.

    Science.gov (United States)

    Valim, Niksa; Brock, James; Niedre, Mark

    2010-01-01

    Time-resolved measurement of early arriving photons through diffusive media has been shown to effectively reduce the high degree of light scatter in biological tissue. However, the experimentally achievable reduction in photon scatter and the impact of time-gated detection on instrument noise performance is not well understood. We measure time-dependent photon density sensitivity functions (PDSFs) between a pulsed laser source and a photomultiplier tube operating in time-correlated single-photon-counting mode. Our data show that with our system, measurement of early arriving photons reduces the full width half maximum of PDSFs on average by about 40 to 60% versus quasicontinuous wave photons over a range of experimental conditions similar to those encountered in small animal tomography, corresponding to a 64 to 84% reduction in PDSF volume. Factoring in noise considerations, the optimal operating point of our instrument is determined to be about the 10% point on the rising edge of the transmitted intensity curve. Time-dependent Monte Carlo simulations and the time-resolved diffusion approximation are used to model photon propagation and are evaluated for agreement with experimental data.

  17. Density Measurements in Low Pressure, Weakly Magnetized, RF Plasmas: Experimental Verification of the Sheath Expansion Effect

    Directory of Open Access Journals (Sweden)

    Yunchao Zhang

    2017-07-01

    Full Text Available This experimental study shows the validity of Sheridan's method in determining plasma density in low pressure, weakly magnetized, RF plasmas using ion saturation current data measured by a planar Langmuir probe. The ion density derived from Sheridan's method which takes into account the sheath expansion around the negatively biased probe tip, presents a good consistency with the electron density measured by a cylindrical RF-compensated Langmuir probe using the Druyvesteyn theory. The ion density obtained from the simplified method which neglects the sheath expansion effect, overestimates the true density magnitude, e.g., by a factor of 3 to 12 for the present experiment.

  18. Experimental Set-up and Full-scale measurements in the ‘Cube'

    DEFF Research Database (Denmark)

    Kalyanova, Olena; Heiselberg, Per

    devices etc. Moreover, the superior control of the thermal conditions in the room adjacent to the DSF and the opening control allow to investigate the DSF both as a part of complete ventilation system and as a separate element of building construction. The test facility is equipped to allow measurements...... of any power supplied to the experimental zone in order to maintain the necessary thermal conditions. An accuracy of these measurements is justified by the quality of the facility construction: ‘the Cube' is very well insulated and tight....

  19. Density measurements in low pressure, weakly magnetized, RF plasmas: experimental verification of the sheath expansion effect

    Science.gov (United States)

    Zhang, Yunchao; Charles, Christine; Boswell, Roderick W.

    2017-07-01

    This experimental study shows the validity of Sheridan's method in determining plasma density in low pressure, weakly magnetized, RF plasmas using ion saturation current data measured by a planar Langmuir probe. The ion density derived from Sheridan's method which takes into account the sheath expansion around the negatively biased probe tip, presents a good consistency with the electron density measured by a cylindrical RF-compensated Langmuir probe using the Druyvesteyn theory. The ion density obtained from the simplified method which neglects the sheath expansion effect, overestimates the true density magnitude, e.g., by a factor of 3 to 12 for the present experiment.

  20. An Effective Experimental Optimization Method for Wireless Power Transfer System Design Using Frequency Domain Measurement

    Directory of Open Access Journals (Sweden)

    Sangyeong Jeong

    2017-10-01

    Full Text Available This paper proposes an experimental optimization method for a wireless power transfer (WPT system. The power transfer characteristics of a WPT system with arbitrary loads and various types of coupling and compensation networks can be extracted by frequency domain measurements. The various performance parameters of the WPT system, such as input real/imaginary/apparent power, power factor, efficiency, output power and voltage gain, can be accurately extracted in a frequency domain by a single passive measurement. Subsequently, the design parameters can be efficiently tuned by separating the overall design steps into two parts. The extracted performance parameters of the WPT system were validated with time-domain experiments.

  1. New experimental validation of the pulse height weighting technique for capture cross-section measurements

    Energy Technology Data Exchange (ETDEWEB)

    Abbondanno, U.; Aerts, G.; Alvarez, H.; Andriamonje, S.; Angelopoulos, A.; Assimakopoulos, P.; Bacri, C.O.; Badurek, G.; Baumann, P.; Becvar, F.; Beer, H.; Benlliure, J.; Berthier, B.; Berthomieux, E.; Boffi, S.; Borcea, C.; Boscolo-Marchi, E.; Bustreo, N.; Calvino, P.; Cano-Ott, D.; Capote, R.; Carlson, P.; Cennini, P.; Chepel, V.; Chiaveri, E.; Coceva, C.; Colonna, N.; Cortes, G.; Cortina, D.; Couture, A.; Cox, J.; Dababneh, S.; Dahlfors, M.; David, S.; Dolfini, R.; Domingo-Pardo, C.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Lourenco, L.; Ferreira-Marques, R.; Frais-Koelbl, H.; Furman, W.I.; Giomataris, Y.; Goncalves, I.F.; Gonzalez-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Gunsing, F.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Ioannides, K.G.; Janeva, N.; Jericha, E.; Kaeppeler, F.; Kadi, Y.; Karamanis, D.; Kelic, A.; Ketlerov, V.; Kitis, G.; Koehler, P.E.; Konovalov, V.; Kossionides, E.; Lacoste, V.; Leeb, H.; Lindote, A.; Lopes, M.I.; Lozano, M.; Lukic, S.; Markov, S.; Marrone, S.; Martinez-Val, J.; Mastinu, P.; Mengoni, A.; Milazzo, P.M.; Minguez, E.; Molina-Coballes, A.; Moreau, C.; Neves, F.; Oberhummer, H.; O' Brien, S.; Pancin, J.; Papaevangelou, T.; Paradela, C.; Pavlik, A.; Pavlopoulos, P.; Perez-Parra, A.; Perlado, J.M.; Perrot, L.; Peskov, V.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Policarpo, A.; Pretel, C.; Quesada, J.M.; Radici, M.; Raman, S.; Rapp, W.; Rauscher, T.; Reifarth, R.; Rejmund, F.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Savvidis, E.; Soares, J.C.; Stephan, C.; Tagliente, G.; Tain, J.L. E-mail: jose.luis.tain@ific.uv.es; Tapia, C.; Tassan-Got, L.; Tavora, L.M.N.; Terlizzi, R.; Terrani, M.; Tsangas, N.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin-Fernandez, D.; Vincente-Vincente, M.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Wendler, H.; Wiescher, M.; Wisshak, K.; Zanini, L

    2004-04-01

    The accuracy of the pulse height weighting technique for the determination of neutron capture cross-sections is investigated. The technique is applied to measurements performed with C{sub 6}D{sub 6} liquid scintillation detectors of two different types using capture samples of various dimensions. The data for well-known (n,{gamma}) resonances are analyzed using weighting functions obtained from Monte Carlo simulations of the experimental set-up. Several causes of systematic deviation are identified and their effect is quantified. In all the cases measured the reaction yield agrees with the standard value within 2%.

  2. Accuracy of mean arterial pressure and blood pressure measurements in predicting pre-eclampsia: systematic review and meta-analysis

    NARCIS (Netherlands)

    Cnossen, Jeltsje S.; Vollebregt, Karlijn C.; de Vrieze, Nynke; ter Riet, Gerben; Mol, Ben W. J.; Franx, Arie; Khan, Khalid S.; van der Post, Joris A. M.

    2008-01-01

    Objective To determine the accuracy of using systolic and diastolic blood pressure, mean arterial pressure, and increase of blood pressure to predict pre-eclampsia. Design Systematic review with meta-analysis of data on test accuracy. Data sources Medline, Embase, Cochrane Library, Medion, checking

  3. VARIABILITY OF CONTINUOUSLY MEASURED ARTERIAL PH AND BLOOD-GAS VALUES IN THE NEAR-TERM FETAL LAMB

    NARCIS (Netherlands)

    WOUDSTRA, BR; DEWOLF, BTHM; SMITS, TM; NATHANIELSZ, PW; ZIJLSTRA, WG; AARNOUDSE, JG

    1995-01-01

    In fetal sheep, arterial blood gas values show considerable spontaneous fluctuations. The aim of the present study was to obtain quantitative data on fetal blood gas variability. Accurate assessment of the intraindividual variations can hardly be obtained from intermittent blood samples, but

  4. Quality of life-associated factors among patients undergoing coronary artery bypass surgery as measured using the WHOQOL-BREF.

    Science.gov (United States)

    Najafi, Mahdi; Sheikhvatan, Mehrdad; Montazeri, Ali

    2009-01-01

    This was a study of the pre-operative factors that influence quality of life (QoL) in patients with coronary artery disease and the relationship between pre-operative QoL and early outcome after coronary artery bypass surgery (CABG). Using the WHOQOL-BREF questionnaire, 283 patients who underwent isolated coronary artery bypass surgery were interviewed and scores were obtained for the physical, psychological, social and environmental components. The study found that the independent physical component predictors for higher QoL included male gender and diabetes mellitus, while the independent psychological component predictors were male gender and high ejection fraction. Males, diabetics and patients with low education levels had higher social well-being than others. Among the postoperative complications, only respiratory failure was found to have a relationship with physical and psychological components. Women with coronary artery disease who were candidates for CABG had lower scores than the men in respect of all components of QoL. Furthermore, a lower pre-operative psychological score in patients undergoing CABG can influence postoperative complications, especially respiratory failure.

  5. Central aortic blood pressure from ultrasound wall-tracking of the carotid artery in children: comparison with invasive measurements and radial tonometry.

    Science.gov (United States)

    Milne, Laura; Keehn, Louise; Guilcher, Antoine; Reidy, John F; Karunanithy, Narayan; Rosenthal, Eric; Qureshi, Shakeel; Chowienczyk, Phil J; Sinha, Manish D

    2015-05-01

    Differences between central aortic root (c) and peripheral (p) systolic blood pressure (SBP) may be particularly marked in children, but noninvasive methods for assessing cSBP in children have not been validated. We compared estimates of cSBP obtained from radiofrequency ultrasound wall tracking of the carotid artery (ART.LAB system) with that measured directly by a catheter in the aortic root at the time of arterial cannulation. Carotid waveforms were calibrated from invasive measurements of mean and diastolic pressures. In 9 children aged 10.5 ± 5.0 years (mean ± SD), cSBP obtained from carotid wall tracking was highly correlated with invasive measures of cSBP (r=0.99) with mean (± SD) difference 3.9 ± 2.5 mm Hg. Second, we compared values of cSBP obtained from the carotid with those obtained using noninvasive applanation tonometry at the radial artery and a radial-to-aortic transfer function (SphygmoCor). Both carotid and radial tonometric measurements were calibrated from the same peripheral mean and diastolic measurements of blood pressure obtained by sphygmomanometry. In 84 children aged 13.2 ± 3.2 years, there was excellent agreement between the 2 methods (r=0.95; Pinvasive validation study confirms that cSBP as estimated by carotid wall tracking provides an acceptable measurement of true cSBP when calibration is from true mean and diastolic pressures. Close agreement of cSBP obtained by carotid wall tracking and radial tonometry suggests that these provide similar results when calibrated from the same peripheral blood pressure measurements. © 2015 American Heart Association, Inc.

  6. An experimental technique for the direct measurement of N2O5 reactivity on ambient particles

    Directory of Open Access Journals (Sweden)

    T. H. Bertram

    2009-06-01

    Full Text Available An experimental approach for the direct measurement of trace gas reactivity on ambient aerosol particles has been developed. The method utilizes a newly designed entrained aerosol flow reactor coupled to a custom-built chemical ionization mass spectrometer. The experimental method is described via application to the measurement of the N2O5 reaction probability, γ (N2O5. Laboratory investigations on well characterized aerosol particles show that measurements of γ (N2O5 observed with this technique are in agreement with previous observations, using conventional flow tube methods, to within ±20% at atmospherically relevant particle surface area concentrations (0–1000 μm2 cm−3. Uncertainty in the measured γ (N2O5 is discussed in the context of fluctuations in potential ambient biases (e.g., temperature, relative humidity and trace gas loadings. Under ambient operating conditions we estimate a single-point uncertainty in γ (N2O5 that ranges between ± (1.3×10-2 + 0.2×γ (N2O5, and ± (1.3×10-3 + 0.2×γ (N2O5 for particle surface area concentrations of 100 to 1000 μm2 cm−3, respectively. Examples from both laboratory investigations and field observations are included alongside discussion of future applications for the reactivity measurement and optimal deployment locations and conditions.

  7. First Experimental Results And Improvements On Profile Measurements With The Vibrating Wire Scanner

    CERN Document Server

    Arutunian, S G; Dobrovolski, N M; Mailian, M R; Soghoyan, H E; Vasiniuk, I E

    2003-01-01

    The paper presents the first experimental results of transverse profile scans using a wire scanner based on a vibrating wire (vibrating wire scanner - VWS). The measurements were performed at the injector electron beam (6 nA) of the Yerevan synchrotron. The beam profile information is obtained by measuring the wire natural oscillations that depend on the wire temperature. This first experiments on weak electron beam proved this new method as a very sensitive tool, even suitable for tail measurements. Additional, improvements were tested to overcome some problems connected with signal conditioning and signal transfer in the presence of electromagnetic noise. As a result the noises were neatly separated and reduced. A mathematical method for rejection of distorted data was developed. Experiments with the scanner at the PETRA accelerator at DESY are planned for measurements of beam tails.

  8. Effects of cardiac timing and peripheral resistance on measurement of pulse wave velocity for assessment of arterial stiffness.

    Science.gov (United States)

    Xiao, Hanguang; Butlin, Mark; Tan, Isabella; Avolio, Alberto

    2017-07-20

    To investigate the effects of heart rate (HR), left ventricular ejection time (LVET) and wave reflection on arterial stiffness as assessed by pulse wave velocity (PWV), a pulse wave propagation simulation system (PWPSim) based on the transmission line model of the arterial tree was developed and was applied to investigate pulse wave propagation. HR, LVET, arterial elastic modulus and peripheral resistance were increased from 60 to 100 beats per minute (bpm), 0.1 to 0.45 seconds, 0.5 to 1.5 times and 0.5 to 1.5 times of the normal value, respectively. Carotid-femoral PWV (cfPWV) and brachial-ankle PWV (baPWV) were calculated by intersecting tangent method (cfPWVtan and baPWVtan), maximum slope (cfPWVmax and baPWVmax), and using the Moens-Korteweg equation ([Formula: see text] and [Formula: see text]). Results showed cfPWV and baPWV increased significantly with arterial elastic modulus but did not increase with HR when using a constant elastic modulus. However there were significant LVET dependencies of cfPWVtan and baPWVtan (0.17 ± 0.13 and 0.17 ± 0.08 m/s per 50 ms), and low peripheral resistance dependencies of cfPWVtan, cfPWVmax, baPWVtan and baPWVmax (0.04 ± 0.01, 0.06 ± 0.04, 0.06 ± 0.03 and 0.09 ± 0.07 m/s per 10% peripheral resistance), respectively. This study demonstrated that LVET dominates the effect on calculated PWV compared to HR and peripheral resistance when arterial elastic modulus is constant.

  9. Can the measurement of brachial artery flow-mediated dilation be applied to the acute exercise model?

    Directory of Open Access Journals (Sweden)

    Harris Ryan A

    2007-11-01

    Full Text Available Abstract The measurement of flow-mediated dilation using high-resolution ultrasound has been utilized extensively in interventional trials evaluating the salutary effect of drugs and lifestyle modifications (i.e. diet or exercise training on endothelial function; however, until recently researchers have not used flow-mediated dilation to examine the role of a single bout of exercise on vascular function. Utilizing the acute exercise model can be advantageous as it allows for an efficient manipulation of exercise variables (i.e. mode, intensity, duration, etc. and permits greater experimental control of confounding variables. Given that the application of flow-mediated dilation in the acute exercise paradigm is expanding, the purpose of this review is to discuss methodological and physiological factors pertinent to flow-mediated dilation in the context of acute exercise. Although the scientific rationale for evaluating endothelial function in response to acute exercise is sound, few concerns warrant attention when interpreting flow-mediated dilation data following acute exercise. The following questions will be addressed in the present review: Does the measurement of flow-mediated dilation influence subsequent serial measures of flow-mediated dilation? Do we need to account for diurnal variation? Is there an optimal time to measure post-exercise flow-mediated dilation? Is the post-exercise flow-mediated dilation reproducible? How is flow-mediated dilation interpreted considering the hemodynamic and sympathetic changes associated with acute exercise? Can the measurement of endothelial-independent dilation affect the exercise? Evidence exists to support the methodological appropriateness for employing flow-mediated dilation in the acute exercise model; however, further research is warranted to clarify its interpretation following acute exercise.

  10. [Measurements of blood velocities using duplex sonography in carotid artery stents: analysis of reliability in an in-vitro model and computational fluid dynamics (CFD)].

    Science.gov (United States)

    Schönwald, U G; Jorczyk, U; Kipfmüller, B

    2011-01-01

    Stents are commonly used for the treatment of occlusive artery diseases in carotid arteries. Today, there is a controversial discussion as to whether duplex sonography (DS) displays blood velocities (BV) that are too high in stented areas. The goal of this study was to evaluate the effect of stenting on DS with respect to BV in artificial carotid arteries. The results of computational fluid dynamics (CFD) were also used for the comparison. To analyze BV using DS, a phantom with a constant flow (70 cm/s) was created. Three different types of stents for carotid arteries were selected. The phantom fluid consisted of 67 % water and 33 % glycerol. All BV measurements were carried out on the last third of the stents. Furthermore, all test runs were simulated using CFD. All measurements were statistically analyzed. DS-derived BV values increased significantly after the placement of the Palmaz Genesis stent (77.6 ± 4.92 cm/sec, p = 0.03). A higher increase in BV values was registered when using the Precise RX stent (80.1 ± 2.01 cm/sec, p CFD simulations showed similar results. Stents have a significant impact on BV, but no effect on DS. The main factor of the blood flow acceleration is the material thickness of the stents. Therefore, different stents need different velocity criteria. Furthermore, the results of computational fluid dynamics prove that CFD can be used to simulate BV in stented silicone tubes. © Georg Thieme Verlag KG Stuttgart · New York.

  11. A non-invasive experimental approach for surface temperature measurements on semi-crystalline thermoplastics

    Science.gov (United States)

    Boztepe, Sinan; Gilblas, Remi; de Almeida, Olivier; Le Maoult, Yannick; Schmidt, Fabrice

    2017-10-01

    Most of the thermoforming processes of thermoplastic polymers and their composites are performed adopting a combined heating and forming stages at which a precursor is heated prior to the forming. This step is done in order to improve formability by softening the thermoplastic polymer. Due to low thermal conductivity and semi-transparency of polymers, infrared (IR) heating is widely used for thermoforming of such materials. Predictive radiation heat transfer models for temperature distributions are therefore critical for optimizations of thermoforming process. One of the key challenges is to build a predictive model including the physical background of radiation heat transfer phenomenon in semi-crystalline thermoplastics as their microcrystalline structure introduces an optically heterogeneous medium. In addition, the accuracy of a predictive model is required to be validated experimentally where IR thermography is one of the suitable methods for such a validation as it provides a non-invasive, full-field surface temperature measurement. Although IR cameras provide a non-invasive measurement, a key issue for obtaining a reliable measurement depends on the optical characteristics of a heated material and the operating spectral band of IR camera. It is desired that the surface of a material to be measured has a spectral band where the material behaves opaque and an employed IR camera operates in the corresponding band. In this study, the optical characteristics of the PO-based polymer are discussed and, an experimental approach is proposed in order to measure the surface temperature of the PO-based polymer via IR thermography. The preliminary analyses showed that IR thermographic measurements may not be simply performed on PO-based polymers and require a correction method as their semi-transparent medium introduce a challenge to obtain reliable surface temperature measurements.

  12. Numerical Simulations and Experimental Measurements of Scale-Model Horizontal Axis Hydrokinetic Turbines (HAHT) Arrays

    Science.gov (United States)

    Javaherchi, Teymour; Stelzenmuller, Nick; Seydel, Joseph; Aliseda, Alberto

    2014-11-01

    The performance, turbulent wake evolution and interaction of multiple Horizontal Axis Hydrokinetic Turbines (HAHT) is analyzed in a 45:1 scale model setup. We combine experimental measurements with different RANS-based computational simulations that model the turbines with sliding-mesh, rotating reference frame and blame element theory strategies. The influence of array spacing and Tip Speed Ratio on performance and wake velocity structure is investigated in three different array configurations: Two coaxial turbines at different downstream spacing (5d to 14d), Three coaxial turbines with 5d and 7d downstream spacing, and Three turbines with lateral offset (0.5d) and downstream spacing (5d & 7d). Comparison with experimental measurements provides insights into the dynamics of HAHT arrays, and by extension to closely packed HAWT arrays. The experimental validation process also highlights the influence of the closure model used (k- ω SST and k- ɛ) and the flow Reynolds number (Re=40,000 to 100,000) on the computational predictions of devices' performance and characteristics of the flow field inside the above-mentioned arrays, establishing the strengths and limitations of existing numerical models for use in industrially-relevant settings (computational cost and time). Supported by DOE through the National Northwest Marine Renewable Energy Center (NNMREC).

  13. Recent gyrokinetic turbulence insights with GENE and direct comparison with experimental measurements

    Science.gov (United States)

    Goerler, Tobias

    2017-10-01

    Throughout the last years direct comparisons between gyrokinetic turbulence simulations and experimental measurements have been intensified substantially. Such studies are largely motivated by the urgent need for reliable transport predictions for future burning plasma devices and the associated necessity for validating the numerical tools. On the other hand, they can be helpful to assess the way a particular diagnostic experiences turbulence and provide ideas for further optimization and the physics that may not yet be accessible. Here, synthetic diagnostics, i.e. models that mimic the spatial and sometimes temporal response of the experimental diagnostic, play an important role. In the contribution at hand, we focus on recent gyrokinetic GENE simulations dedicated to ASDEX Upgrade L-mode plasmas and comparison with various turbulence measurements. Particular emphasis will be given to density fluctuation spectra which are experimentally accessible via Doppler reflectometry. A sophisticated synthetic diagnostic involving a fullwave code has recently been established and solves the long-lasting question on different spectral roll-overs in gyrokinetic and measured spectra as well as the potentially different power laws in the O- and X-mode signals. The demonstrated agreement furthermore extends the validation data base deep into spectral space and confirms a proper coverage of the turbulence cascade physics. The flux-matched GENE simulations are then used to study the sensitivity of the latter to the main microinstability drive and investigate the energetics at the various scales. Additionally, electron scale turbulence based modifications of the high-k power law spectra in such plasmas will be presented and their visibility in measurable signals be discussed.

  14. Characterisation of large area THGEMs and experimental measurement of the Townsend coefficients for CF4

    Science.gov (United States)

    Burns, J.; Crane, T.; Ezeribe, A. C.; Grove, C. L.; Lynch, W.; Scarff, A.; Spooner, N. J. C.; Steer, C.

    2017-10-01

    Whilst the performance of small THGEMs is well known, here we consider the challenges in scaling these up to large area charge readouts. We first verify the expected gain of larger THGEMs by reporting experimental Townsend coefficients for a 10 cm diameter THGEM in low-pressure CF4. Large area 50 cm by 50 cm THGEMs were sourced from a commercial PCB supplier and geometrical imperfections were observed which we quantified using an optical camera setup. The large area THGEMs were experimentally characterised at Boulby Underground Laboratory through a series of gain calibrations and alpha spectrum measurements. ANSYS, Magboltz and Garfield++ simulations of the design of a TPC based on the large area THGEMs are presented. We also consider their implications for directional dark matter research and potential applications within nuclear security.

  15. Experimental measurements and numerical simulation of permittivity and permeability of Teflon in X band

    Directory of Open Access Journals (Sweden)

    Adriano Luiz de Paula

    2011-01-01

    Full Text Available Recognizing the importance of an adequate characterization of radar absorbing materials, and consequently their development, the present study aims to contribute for the establishment and validation of experimental determination and numerical simulation of electromagnetic materials complex permittivity and permeability, using a Teflon® sample. The present paper branches out into two related topics. The first one is concerned about the implementation of a computational modeling to predict the behavior of electromagnetic materials in confined environment by using electromagnetic three-dimensional simulation. The second topic re-examines the Nicolson-Ross-Weir mathematical model to retrieve the constitutive parameters (complex permittivity and permeability of a homogeneous sample (Teflon®, from scattering coefficient measurements. The experimental and simulated results show a good convergence that guarantees the application of the used methodologies for the characterization of different radar absorbing materials samples.

  16. The Measurement of Electron-Induced Erosion of Condensed Gases: Experimental Methods

    DEFF Research Database (Denmark)

    Schou, Jørgen; Sørensen, H.; Børgesen, P.

    1984-01-01

    Two experimental methods for measuring the erosion yield of condensed gases are described. One, the frequency-change method, utilizes a quartz-crystal microbalance operating at liquid-helium temperature. The other, the emissivity-change method is based on the strongly varying electron emission...... as a function of the condensed-gas film thickness. Satisfactory results have been obtained for both methods for solid Ne and D2 at electron energies up to 3 keV, and the mutual agreement is good as well. Accurate measurements are affected critically by the beam conditions, particularly if the erosion yield...... depends on the film thickness. The erosion yield has been measured for dominant electron sputtering of solid Ne ( ≈ 28 Ne-atoms/electron) as well as for beam-induced evaporation at 2 keV. In the latter case a clear lateral broadening of the erosion spot is observed....

  17. Quantum Steering Inequality with Tolerance for Measurement-Setting Errors: Experimentally Feasible Signature of Unbounded Violation.

    Science.gov (United States)

    Rutkowski, Adam; Buraczewski, Adam; Horodecki, Paweł; Stobińska, Magdalena

    2017-01-13

    Quantum steering is a relatively simple test for proving that the values of quantum-mechanical measurement outcomes come into being only in the act of measurement. By exploiting quantum correlations, Alice can influence-steer-Bob's physical system in a way that is impossible in classical mechanics, as shown by the violation of steering inequalities. Demonstrating this and similar quantum effects for systems of increasing size, approaching even the classical limit, is a long-standing challenging problem. Here, we prove an experimentally feasible unbounded violation of a steering inequality. We derive its universal form where tolerance for measurement-setting errors is explicitly built in by means of the Deutsch-Maassen-Uffink entropic uncertainty relation. Then, generalizing the mutual unbiasedness, we apply the inequality to the multisinglet and multiparticle bipartite Bell state. However, the method is general and opens the possibility of employing multiparticle bipartite steering for randomness certification and development of quantum technologies, e.g., random access codes.

  18. Experimental Characterization of Ultra-Wideband Channel Parameter Measurements in an Underground Mine

    Directory of Open Access Journals (Sweden)

    B. Nkakanou

    2011-01-01

    Full Text Available Experimental results for an ultra-wideband (UWB channel parameters in an underground mining environment over a frequency range of 3 GHz to 10 GHz are reported. The measurements were taken both in LOS and NLOS cases in two different size mine galleries. In the NLOS case, results were acquired for different corridor obstruction angles. The results were obtained during an extensive measurement campaign in the UWB frequency, and the measurement procedure allows both the large- and small-scale parameters such as the path loss exponent, coherence bandwidth, and so forth, to be quantified. The capacity of the UWB channel as a function of the physical depth of the mine gallery has also been recorded for comparison purposes.

  19. Impact of volunteer-related and methodology-related factors on the reproducibility of brachial artery flow-mediated vasodilation: analysis of 672 individual repeated measurements.

    Science.gov (United States)

    van Mil, Anke C C M; Greyling, Arno; Zock, Peter L; Geleijnse, Johanna M; Hopman, Maria T; Mensink, Ronald P; Reesink, Koen D; Green, Daniel J; Ghiadoni, Lorenzo; Thijssen, Dick H

    2016-09-01

    Brachial artery flow-mediated dilation (FMD) is a popular technique to examine endothelial function in humans. Identifying volunteer and methodological factors related to variation in FMD is important to improve measurement accuracy and applicability. Volunteer-related and methodology-related parameters were collected in 672 volunteers from eight affiliated centres worldwide who underwent repeated measures of FMD. All centres adopted contemporary expert-consensus guidelines for FMD assessment. After calculating the coefficient of variation (%) of the FMD for each individual, we constructed quartiles (n = 168 per quartile). Based on two regression models (volunteer-related factors and methodology-related factors), statistically significant components of these two models were added to a final regression model (calculated as β-coefficient and R). This allowed us to identify factors that independently contributed to the variation in FMD%. Median coefficient of variation was 17.5%, with healthy volunteers demonstrating a coefficient of variation 9.3%. Regression models revealed age (β = 0.248, P measurements (β = 0.318, P measurements, hypertension, baseline FMD% and lab experience with FMD independently predicted brachial artery variability (total R = 0.202). Although FMD% showed good reproducibility, larger variation was observed in conditions with longer time between measurements, hypertension, less experience and lower baseline FMD%. Accounting for these factors may improve FMD% variability.

  20. Investigation of dynamic SPECT measurements of the arterial input function in human subjects using simulation, phantom and human studies

    OpenAIRE

    Winant, Celeste D.; Aparici, Carina Mari; Zelnik, Yuval R.; Reutter, Bryan W.; Sitek, Arkadiusz; Bacharach, Stephen L.; Gullberg, Grant T

    2011-01-01

    Computer simulations, a phantom study and a human study were performed to determine whether a slowly rotating single-photon computed emission tomography (SPECT) system could provide accurate arterial input functions for quantification of myocardial perfusion imaging using kinetic models. The errors induced by data inconsistency associated with imaging with slow camera rotation during tracer injection were evaluated with an approach called SPECT/P (dynamic SPECT from positron emission tomograp...

  1. Determination of bleb capsule porosity with an experimental glaucoma drainage device and measurement system.

    Science.gov (United States)

    Ross, Craig; Pandav, Surinder Singh; Li, Yu Qin; Nguyen, Dan Q; Beirne, Stephen; Wallace, Gordon G; Shaarawy, Tarek; Crowston, Jonathan G; Coote, Michael

    2015-05-01

    Control of intraocular pressure after implantation of a glaucoma drainage device (GDD) depends on the porosity of the capsule that forms around the plate of the GDD. To compare capsular porosity after insertion of 2 different GDDs using a novel implant and measurement system. We performed an experimental interventional study at an eye research facility in a tertiary eye care center. Testing was performed on 22 adult New Zealand white rabbits that received the experimental GDD or an existing GDD. A new experimental GDD, the Center for Eye Research Australia (CERA) implant, was created using computer-aided design and a 3-dimensional printer. The CERA GDDs were implanted in the eyes of rabbits randomized into 1 of the following 3 groups: with no connection to the anterior chamber (n = 7), with connection to the anterior chamber for 1 week (n = 5), and with connection to the anterior chamber for 4 weeks (n = 5). In a control group (n = 5), a pediatric GDD was implanted without connection to the anterior chamber. We measured the capsular porosity using a pressure-gated picoliter pump at a driving pressure of 12 mm Hg. The animals were killed humanely for histologic study. Porosity of the fibrous capsule around the implant. We found no difference in mean (SEM) capsular porosity between the CERA (3.39 [0.76; 95% CI, 1.43-5.48] µL/min) and pediatric (4.52 [0.52; 95% CI, 3.19-5.95] µL/min) GDDs (P = .28, unpaired t test) at 4 weeks without aqueous exposure. Mean (SEM) capsular porosity of CERA GDDs connected to the anterior chamber at 1 week was 2.46 (0.36; 95% CI, 1.55-3.44) µL/min but decreased to 0.67 (0.07; 95% CI, 0.49-0.86) µL/min at 4 weeks (P = .001, unpaired t test). Our experimental method permits direct measurement of capsular porosity of an in situ GDD. In a comparison between an experimental (CERA) and an existing GDD, no differences were identified in capsular porosity or histologic reaction between the implants. These results suggest that the CERA GDD

  2. Measuring saliency in images: which experimental parameters for the assessment of image quality?

    Science.gov (United States)

    Fredembach, Clement; Woolfe, Geoff; Wang, Jue

    2012-01-01

    Predicting which areas of an image are perceptually salient or attended to has become an essential pre-requisite of many computer vision applications. Because observers are notoriously unreliable in remembering where they look a posteriori, and because asking where they look while observing the image necessarily in uences the results, ground truth about saliency and visual attention has to be obtained by gaze tracking methods. From the early work of Buswell and Yarbus to the most recent forays in computer vision there has been, perhaps unfortunately, little agreement on standardisation of eye tracking protocols for measuring visual attention. As the number of parameters involved in experimental methodology can be large, their individual in uence on the nal results is not well understood. Consequently, the performance of saliency algorithms, when assessed by correlation techniques, varies greatly across the literature. In this paper, we concern ourselves with the problem of image quality. Specically: where people look when judging images. We show that in this case, the performance gap between existing saliency prediction algorithms and experimental results is signicantly larger than otherwise reported. To understand this discrepancy, we rst devise an experimental protocol that is adapted to the task of measuring image quality. In a second step, we compare our experimental parameters with the ones of existing methods and show that a lot of the variability can directly be ascribed to these dierences in experimental methodology and choice of variables. In particular, the choice of a task, e.g., judging image quality vs. free viewing, has a great impact on measured saliency maps, suggesting that even for a mildly cognitive task, ground truth obtained by free viewing does not adapt well. Careful analysis of the prior art also reveals that systematic bias can occur depending on instrumental calibration and the choice of test images. We conclude this work by proposing a

  3. Investigation of dynamic SPECT measurements of the arterial input function in human subjects using simulation, phantom and human studies.

    Science.gov (United States)

    Winant, Celeste D; Aparici, Carina Mari; Zelnik, Yuval R; Reutter, Bryan W; Sitek, Arkadiusz; Bacharach, Stephen L; Gullberg, Grant T

    2012-01-21

    Computer simulations, a phantom study and a human study were performed to determine whether a slowly rotating single-photon computed emission tomography (SPECT) system could provide accurate arterial input functions for quantification of myocardial perfusion imaging using kinetic models. The errors induced by data inconsistency associated with imaging with slow camera rotation during tracer injection were evaluated with an approach called SPECT/P (dynamic SPECT from positron emission tomography (PET)) and SPECT/D (dynamic SPECT from database of SPECT phantom projections). SPECT/P simulated SPECT-like dynamic projections using reprojections of reconstructed dynamic (94)Tc-methoxyisobutylisonitrile ((94)Tc-MIBI) PET images acquired in three human subjects (1 min infusion). This approach was used to evaluate the accuracy of estimating myocardial wash-in rate parameters K(1) for rotation speeds providing 180° of projection data every 27 or 54 s. Blood input and myocardium tissue time-activity curves (TACs) were estimated using spatiotemporal splines. These were fit to a one-compartment perfusion model to obtain wash-in rate parameters K(1). For the second method (SPECT/D), an anthropomorphic cardiac torso phantom was used to create real SPECT dynamic projection data of a tracer distribution derived from (94)Tc-MIBI PET scans in the blood pool, myocardium, liver and background. This method introduced attenuation, collimation and scatter into the modeling of dynamic SPECT projections. Both approaches were used to evaluate the accuracy of estimating myocardial wash-in parameters for rotation speeds providing 180° of projection data every 27 and 54 s. Dynamic cardiac SPECT was also performed in a human subject at rest using a hybrid SPECT/CT scanner. Dynamic measurements of (99m)Tc-tetrofosmin in the myocardium were obtained using an infusion time of 2 min. Blood input, myocardium tissue and liver TACs were estimated using the same spatiotemporal splines. The

  4. Investigation of dynamic SPECT measurements of the arterial input function in human subjects using simulation, phantom and human studies

    Science.gov (United States)

    Winant, Celeste D.; Aparici, Carina Mari; Zelnik, Yuval R.; Reutter, Bryan W.; Sitek, Arkadiusz; Bacharach, Stephen L.; Gullberg, Grant T.

    2012-01-01

    Computer simulations, a phantom study and a human study were performed to determine whether a slowly rotating single-photon computed emission tomography (SPECT) system could provide accurate arterial input functions for quantification of myocardial perfusion imaging using kinetic models. The errors induced by data inconsistency associated with imaging with slow camera rotation during tracer injection were evaluated with an approach called SPECT/P (dynamic SPECT from positron emission tomography (PET)) and SPECT/D (dynamic SPECT from database of SPECT phantom projections). SPECT/P simulated SPECT-like dynamic projections using reprojections of reconstructed dynamic 94Tc-methoxyisobutylisonitrile (94Tc-MIBI) PET images acquired in three human subjects (1 min infusion). This approach was used to evaluate the accuracy of estimating myocardial wash-in rate parameters K1 for rotation speeds providing 180° of projection data every 27 or 54 s. Blood input and myocardium tissue time-activity curves (TACs) were estimated using spatiotemporal splines. These were fit to a one-compartment perfusion model to obtain wash-in rate parameters K1. For the second method (SPECT/D), an anthropomorphic cardiac torso phantom was used to create real SPECT dynamic projection data of a tracer distribution derived from 94Tc-MIBI PET scans in the blood pool, myocardium, liver and background. This method introduced attenuation, collimation and scatter into the modeling of dynamic SPECT projections. Both approaches were used to evaluate the accuracy of estimating myocardial wash-in parameters for rotation speeds providing 180° of projection data every 27 and 54 s. Dynamic cardiac SPECT was also performed in a human subject at rest using a hybrid SPECT/CT scanner. Dynamic measurements of 99mTc-tetrofosmin in the myocardium were obtained using an infusion time of 2 min. Blood input, myocardium tissue and liver TACs were estimated using the same spatiotemporal splines. The spatiotemporal maximum

  5. Experimental Evaluation of an Invasive Medical Instrument Based on a Displacement Measurement System.

    Science.gov (United States)

    Fotiadis, Dimitris A; Astaras, Alexandros; Bamidis, Panagiotis D; Papathanasiou, Kostas; Kalfas, Anestis

    2015-09-01

    This paper presents a novel method for tracking the position of a medical instrument's tip. The system is based on phase locking a high frequency signal transmitted from the medical instrument's tip to a reference signal. Displacement measurement is established having the loop open, in order to get a low frequency voltage representing the medical instrument's movement; therefore, positioning is established by means of conventional measuring techniques. The voltage-controlled oscillator stage of the phase-locked loop (PLL), combined to an appropriate antenna, comprises the associated transmitter located inside the medical instrument tip. All the other low frequency PLL components, low noise amplifier and mixer, are located outside the human body, forming the receiver part of the system. The operating details of the proposed system were coded in Verilog-AMS. Simulation results indicate robust medical instrument tracking in 1-D. Experimental evaluation of the proposed position tracking system is also presented. The experiments described in this paper are based on a transmitter moving opposite a stationary receiver performing either constant velocity or uniformly accelerated movement, and also together with two stationary receivers performing constant velocity movement again. This latter setup is implemented in order to demonstrate the prototype's accuracy for planar (2-D) motion measurements. Error analysis and time-domain analysis are presented for system performance characterization. Furthermore, preliminary experimental assessment using a saline solution container to more closely approximate the human body as a radio frequency wave transmission medium has proved the system's capability of operating underneath the skin.

  6. An experimental concept to measure opacities under solar-relevant conditions

    Science.gov (United States)

    Keiter, Paul A.; Mussack, Katie; Klein, Sallee R.

    2013-06-01

    Recent solar abundance models (Asplund 2009) use a significantly lower abundance for C, N, O compared to models used roughly a decade ago. Although the models used now are much more sophisticated than before, a discrepancy still exists between the abundances in the models and the abundances determined by helioseismic measurements. Agreement can be obtained by ad hoc adjustments to the opacity of high-Z (Z > 2) elements ranging from a few percent in the solar interior to as much as 30 just below the convection zone (CZ). Although many of the opacity models are thought to agree within a few percent, a recent element-by-element study (Blancard 2012) indicates a larger disagreement between models for certain elements. Experimental opacity measurements for these elements in the regimes of interest will provide valuable information to help resolve these discrepancies. We will present an experimental platform designed to measure the opacity of C, N, and O and discuss the achievable parameter regime. We will also briefly discuss how this platform can be extended to include other high-Z elements.

  7. A novel full-field experimental method to measure the local compressibility of gas diffusion media

    Science.gov (United States)

    Lai, Yeh-Hung; Li, Yongqiang; Rock, Jeffrey A.

    The gas diffusion medium (GDM) in a proton exchange membrane (PEM) fuel cell needs to simultaneously satisfy the requirements of transporting reactant gases, removing product water, conducting electrons and heat, and providing mechanical support to the membrane electrode assembly (MEA). Concerning the localized over-compression which may force carbon fibers and other conductive debris into the membrane to cause fuel cell failure by electronically shorting through the membrane, we have developed a novel full-field experimental method to measure the local thickness and compressibility of GDM. Applying a uniform air pressure upon a thin polyimide film bonded on the top surface of the GDM with support from the bottom by a flat metal substrate and measuring the thickness change using the 3-D digital image correlation technique with an out-of-plane displacement resolution less than 0.5 μm, we have determined the local thickness and compressive stress/strain behavior in the GDM. Using the local thickness and compressibility data over an area of 11.2 mm × 11.2 mm, we numerically construct the nominal compressive response of a commercial Toray™ TGP-H-060 based GDM subjected to compression by flat platens. Good agreement in the nominal stress/strain curves from the numerical construction and direct experimental flat-platen measurement confirms the validity of the methodology proposed in this article. The result shows that a nominal pressure of 1.4 MPa compressed between two flat platens can introduce localized compressive stress concentration of more than 3 MPa in up to 1% of the total area at various locations from several hundred micrometers to 1 mm in diameter. We believe that this full-field experimental method can be useful in GDM material and process development to reduce the local hard spots and help to mitigate the membrane shorting failure in PEM fuel cells.

  8. Modeling of a pitching and plunging airfoil using experimental flow field and load measurements

    Science.gov (United States)

    Troshin, Victor; Seifert, Avraham

    2018-01-01

    The main goal of the current paper is to outline a low-order modeling procedure of a heaving airfoil in a still fluid using experimental measurements. Due to its relative simplicity, the proposed procedure is applicable for the analysis of flow fields within complex and unsteady geometries and it is suitable for analyzing the data obtained by experimentation. Currently, this procedure is used to model and predict the flow field evolution using a small number of low profile load sensors and flow field measurements. A time delay neural network is used to estimate the flow field. The neural network estimates the amplitudes of the most energetic modes using four sensory inputs. The modes are calculated using proper orthogonal decomposition of the flow field data obtained experimentally by time-resolved, phase-locked particle imaging velocimetry. To permit the use of proper orthogonal decomposition, the measured flow field is mapped onto a stationary domain using volume preserving transformation. The analysis performed by the model showed good estimation quality within the parameter range used in the training procedure. However, the performance deteriorates for cases out of this range. This situation indicates that, to improve the robustness of the model, both the decomposition and the training data sets must be diverse in terms of input parameter space. In addition, the results suggest that the property of volume preservation of the mapping does not affect the model quality as long as the model is not based on the Galerkin approximation. Thus, it may be relaxed for cases with more complex geometry and kinematics.

  9. Results of experimental tests and calibrations of the surface neutron moisture measurement probe

    Energy Technology Data Exchange (ETDEWEB)

    Watson, W.T.; Bussell, J.H., Westinghouse Hanford

    1996-08-13

    The surface neutron moisture probe has been tested both to demonstrate that is is able to operate in the expected in-tank temperature and gamma-ray fields and to provide detector responses to known moisture concentration materials. The probe will properly function in a simultaneous high temperature (80 degrees C) and high gamma radiation field (210 rad/hr)environment. Comparisons between computer model predicted and experimentally measured detector responses to changes in moisture provide a basis for the probe calibration to in-tank moisture concentrations.

  10. Optical waveguiding and applied photonics technological aspects, experimental issue approaches and measurements

    CERN Document Server

    Massaro, Alessandro

    2012-01-01

    Optoelectronics--technology based on applications light such as micro/nano quantum electronics, photonic devices, laser for measurements and detection--has become an important field of research. Many applications and physical problems concerning optoelectronics are analyzed in Optical Waveguiding and Applied Photonics.The book is organized in order to explain how to implement innovative sensors starting from basic physical principles. Applications such as cavity resonance, filtering, tactile sensors, robotic sensor, oil spill detection, small antennas and experimental setups using lasers are a

  11. Experimental investigation on the magneto-optic effects of ferrofluids via dynamic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Jamon, D. [Laboratory DIOM, Universite Jean Monnet, 23 rue du Dr Paul Michelon, 42023 Saint-Etienne Cedex 2 (France); Donatini, F. [Institut Neel, CNRS et Universite Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); Siblini, A. [Laboratory DIOM, Universite Jean Monnet, 23 rue du Dr Paul Michelon, 42023 Saint-Etienne Cedex 2 (France); Royer, F. [Laboratory DIOM, Universite Jean Monnet, 23 rue du Dr Paul Michelon, 42023 Saint-Etienne Cedex 2 (France)], E-mail: Francois.Royer@univ-st-etienne.fr; Perzynski, R.; Cabuil, V.; Neveu, S. [LI2C, UMR 7612, Universite P and M Curie, 4 place Jussieu, 75252 Paris Cedex 05 (France)

    2009-05-15

    An experimental investigation on the origin of the magneto-optic effects of ferrofluids is presented. Dynamic measurements of their transverse and longitudinal magneto-optic effects and their magnetic properties have been performed. As ferrofluids are colloidal suspensions of magnetic particles in a liquid, the influence of two parameters has been studied: the magnetic anisotropy energy of particles and the carrier liquid viscosity for four ferrofluid samples. The interpretation and the comparison of results give some clues for a better understanding of magneto-optical effects of ferrofluids.

  12. Experimental and Numerical Study on Pressure Distribution of 90° Elbow for Flow Measurement

    Directory of Open Access Journals (Sweden)

    Beibei Feng

    2014-01-01

    Full Text Available Numerical simulation is performed to investigate the pressure distribution of helium gas under high pressure and high temperature for 10 MW High Temperature Gas-Cooled Reactor (HTGR-10. Experimental studies are first conducted on a self-built test system to investigate the static pressure distribution of a 90° elbow and validate the credibility of the computational approach. The 90° elbow is designed and manufactured geometrically the same as HTGR-10. Based on the experimental data, comparison of static pressure of inner wall and outer wall of 90° elbow with numerical results is carried out to verify the numerical approach. With high agreement between experimental results and numerical results of water flowing through 90° elbow, flow characteristics of helium gas under high pressure and high temperature are investigated on the confirmed numerical approach for flow measurement. And wall pressure distribution of eight cross sections of 90° elbow is given in detail to represent the entire region of the elbow.

  13. A theoretical and experimental investigation of graph theoretical measures for land development in satellite imagery.

    Science.gov (United States)

    Unsalan, Cem; Boyer, Kim L

    2005-04-01

    Today's commercial satellite images enable experts to classify region types in great detail. In previous work, we considered discriminating rural and urban regions [23]. However, a more detailed classification is required for many purposes. These fine classifications assist government agencies in many ways including urban planning, transportation management, and rescue operations. In a step toward the automation of the fine classification process, this paper explores graph theoretical measures over grayscale images. The graphs are constructed by assigning photometric straight line segments to vertices, while graph edges encode their spatial relationships. We then introduce a set of measures based on various properties of the graph. These measures are nearly monotonic (positively correlated) with increasing structure (organization) in the image. Thus, increased cultural activity and land development are indicated by increases in these measures-without explicit extraction of road networks, buildings, residences, etc. These latter, time consuming (and still only partially automated) tasks can be restricted only to "promising" image regions, according to our measures. In some applications our measures may suffice. We present a theoretical basis for the measures followed by extensive experimental results in which the measures are first compared to manual evaluations of land development. We then present and test a method to focus on, and (pre)extract, suburban-style residential areas. These are of particular importance in many applications, and are especially difficult to extract. In this work, we consider commercial IKONOS data. These images are orthorectified to provide a fixed resolution of 1 meter per pixel on the ground. They are, therefore, metric in the sense that ground distance is fixed in scale to pixel distance. Our data set is large and diverse, including sea and coastline, rural, forest, residential, industrial, and urban areas.

  14. POVERTY, WELL-BEING AND SUSTAINABLE DEVELOPMENT: OFFICIAL AND EXPERIMENTAL MEASURES IN POSTMODERN SOCIETIES

    Directory of Open Access Journals (Sweden)

    RALUCA I. IORGULESCU

    2014-02-01

    Full Text Available Poverty and well-being are concepts that cannot be separated, and research on poverty is implicitly linked to welfare economics. Poverty, in the complex conditions of modern societies affected by financial and economic crises, requires a clear definition and measures as accurate as possible. The paper presents some issues related to official methods and techniques for estimating poverty. Three steps necessary for poverty measurement are introduced and, also, multidimensional and poverty dynamics analyses are highlighted as important issues for poverty eradication policies. Results on youth poverty dynamics, the duration and recurrence of poverty and the perpetuation of poverty in EU countries are presented. The concepts of poverty risk, as well as some results of the search for key factors influencing the likelihood of being at risk of poverty, is discussed. Traditionally the living standard of households is measured by income, but recently other tools for measuring well-being in the broader framework of postmodern societies have been developed. As examples are some experimental methods and techniques for estimating poverty introduced in the U.S. and the European Union. Also, in the context of discussions related to the design of policies for sustainable development, some aspects of well-being measures in ecological economics are presented.

  15. Synchrotron radiation measurement of multiphase fluid saturations in porous media: Experimental technique and error analysis

    Science.gov (United States)

    Tuck, David M.; Bierck, Barnes R.; Jaffé, Peter R.

    1998-06-01

    Multiphase flow in porous media is an important research topic. In situ, nondestructive experimental methods for studying multiphase flow are important for improving our understanding and the theory. Rapid changes in fluid saturation, characteristic of immiscible displacement, are difficult to measure accurately using gamma rays due to practical restrictions on source strength. Our objective is to describe a synchrotron radiation technique for rapid, nondestructive saturation measurements of multiple fluids in porous media, and to present a precision and accuracy analysis of the technique. Synchrotron radiation provides a high intensity, inherently collimated photon beam of tunable energy which can yield accurate measurements of fluid saturation in just one second. Measurements were obtained with precision of ±0.01 or better for tetrachloroethylene (PCE) in a 2.5 cm thick glass-bead porous medium using a counting time of 1 s. The normal distribution was shown to provide acceptable confidence limits for PCE saturation changes. Sources of error include heat load on the monochromator, periodic movement of the source beam, and errors in stepping-motor positioning system. Hypodermic needles pushed into the medium to inject PCE changed porosity in a region approximately ±1 mm of the injection point. Improved mass balance between the known and measured PCE injection volumes was obtained when appropriate corrections were applied to calibration values near the injection point.

  16. Experimental Results of Site Calibration and Sensitivity Measurements in OTR for UWB Systems

    Science.gov (United States)

    Viswanadham, Chandana; Rao, P. Mallikrajuna

    2017-06-01

    System calibration and parameter accuracy measurement of electronic support measures (ESM) systems is a major activity, carried out by electronic warfare (EW) engineers. These activities are very critical and needs good understanding in the field of microwaves, antennas, wave propagation, digital and communication domains. EW systems are broad band, built with state-of-the art electronic hardware, installed on different varieties of military platforms to guard country's security from time to time. EW systems operate in wide frequency ranges, typically in the order of thousands of MHz, hence these are ultra wide band (UWB) systems. Few calibration activities are carried within the system and in the test sites, to meet the accuracies of final specifications. After calibration, parameters are measured for their accuracies either in feed mode by injecting the RF signals into the front end or in radiation mode by transmitting the RF signals on to system antenna. To carry out these activities in radiation mode, a calibrated open test range (OTR) is necessary in the frequency band of interest. Thus site calibration of OTR is necessary to be carried out before taking up system calibration and parameter measurements. This paper presents the experimental results of OTR site calibration and sensitivity measurements of UWB systems in radiation mode.

  17. Experimental Method for Determination of Self-Heating at the Point of Measurement

    Science.gov (United States)

    Sestan, D.; Zvizdic, D.; Grgec-Bermanec, L.

    2017-09-01

    This paper presents a new experimental method and algorithm for the determination of self-heating of platinum resistance thermometer (PRT) when the temperature instability of medium of interest would prevent an accurate self-heating determination using standard methods. In temperature measurements performed by PRT, self-heating is one of the most common sources of error and arises from the increase in sensor temperature caused by the dissipation of electrical heat when measurement current is applied to the temperature sensing element. This increase depends mainly on the applied current and the thermal resistances between thermometer sensing element and the environment surrounding the thermometer. The method is used for determination of self-heating of a 100 Ω industrial PRT which is intended for measurement of air temperature inside the saturation chamber of the primary dew/frost point generator at the Laboratory for Process Measurement (HMI/FSB-LPM). Self-heating is first determined for conditions present during the comparison calibration of the thermometer, using the calibration bath. The measurements were then repeated with thermometer being placed in an air stream inside the saturation chamber. The experiment covers the temperature range between -65°C and 10°C. Self-heating is determined for two different air velocities and two different vertical positions of PRT in relation to the chamber bottom.

  18. Uncertainty in techno-economic estimates of cellulosic ethanol production due to experimental measurement uncertainty

    Directory of Open Access Journals (Sweden)

    Vicari Kristin J

    2012-04-01

    Full Text Available Abstract Background Cost-effective production of lignocellulosic biofuels remains a major financial and technical challenge at the industrial scale. A critical tool in biofuels process development is the techno-economic (TE model, which calculates biofuel production costs using a process model and an economic model. The process model solves mass and energy balances for each unit, and the economic model estimates capital and operating costs from the process model based on economic assumptions. The process model inputs include experimental data on the feedstock composition and intermediate product yields for each unit. These experimental yield data are calculated from primary measurements. Uncertainty in these primary measurements is propagated to the calculated yields, to the process model, and ultimately to the economic model. Thus, outputs of the TE model have a minimum uncertainty associated with the uncertainty in the primary measurements. Results We calculate the uncertainty in the Minimum Ethanol Selling Price (MESP estimate for lignocellulosic ethanol production via a biochemical conversion process: dilute sulfuric acid pretreatment of corn stover followed by enzymatic hydrolysis and co-fermentation of the resulting sugars to ethanol. We perform a sensitivity analysis on the TE model and identify the feedstock composition and conversion yields from three unit operations (xylose from pretreatment, glucose from enzymatic hydrolysis, and ethanol from fermentation as the most important variables. The uncertainty in the pretreatment xylose yield arises from multiple measurements, whereas the glucose and ethanol yields from enzymatic hydrolysis and fermentation, respectively, are dominated by a single measurement: the fraction of insoluble solids (fIS in the biomass slurries. Conclusions We calculate a $0.15/gal uncertainty in MESP from the TE model due to uncertainties in primary measurements. This result sets a lower bound on the error bars of

  19. Experimental Study of Imbibition Characteristics of Silica Sol in Coal-Measure Mudstone Matrix

    Directory of Open Access Journals (Sweden)

    Dongjiang Pan

    2017-03-01

    Full Text Available Coal-measure mudstone is a typical dual-porosity media, and grouting in a matrix system is dominantly controlled by the imbibition effect for silica sol. This paper studies the imbibition effect using mudstone in the Huaibei mining area and silica sol as grouting material as an example. Groutability, driving force, and diffusion difficulty affecting the imbibition effect were tested by a mercury porosimeter, nanoparticle size analyzer, optical contact-angle measuring device, surface tension meter, and rotary viscosity meter. After finely grinding a mudstone sample, a pressureless imbibition process was conducted through nuclear magnetic resonance equipment for 216 h to study colloid spontaneous migration and phase characteristics. Results show that silica sol absorption rate follows a power function and that the spectrograms of T2 are distributed in a triple peak pattern, with a tendency to move to the right of vertex time. The paper lays a theoretical and experimental foundation for field grouting in the coal mine.

  20. Experimental measurement of the plasma conductivity of Z93 and Z93P thermal control paint

    Science.gov (United States)

    Hillard, G. Barry

    1993-01-01

    Two samples each of Z93 and Z93P thermal control paint were exposed to a simulated space environment in a plasma chamber. The samples were biased through a series of voltages ranging from -200 volts to +300 volts and electron and ion currents measured. By comparing the currents to those of pure metal samples of the same size and shape, the conductivity of the samples was calculated. Measured conductivity was dependent on the bias potential in all cases. For Z93P, conductivity was approximately constant over much of the bias range and we find a value of 0.5 micro-mhos per square meter for both electron and ion current. For Z93, the dependence on bias was much more pronounced but conductivity can be said to be approximately one order of magnitude larger. In addition to presenting these results, this report documents all of the experimental data as well as the statistical analyses performed.

  1. Experimental apparatus for measurement of density of supercooled water at high pressure

    Directory of Open Access Journals (Sweden)

    Peukert Pavel

    2012-04-01

    Full Text Available Thermodynamic behavior of supercooled water (metastable fluid water existing transiently below the equilibrium freezing point at high pressures was subject to many recent theoretical studies. Some of them assume that a second critical point of water exists, related to two liquid phases of supercooled water: the low-density liquid and the high-density liquid. To test these theories, an original experimental cryogenic apparatus is being developed. The volume changes are measured optically in custom-treated fused-silica capillary tubes. The capillaries are placed in a metal vessel designed for pressures up to 200 MPa. The vessel is connected to a circulation thermostat enabling a rapid change of temperature to prevent freezing. A new high-vacuum device was developed for degassing of the ultrapure water sample and filling it into the measuring capillaries. The experiments will contribute to fundamental understanding of the anomalous behavior of water and to applications in meteorology, aerospace engineering, cryobiology etc.

  2. Experimental measurement and Monte Carlo assessment of Argon-41 production in a PET cyclotron facility.

    Science.gov (United States)

    Infantino, Angelo; Valtieri, Lorenzo; Cicoria, Gianfranco; Pancaldi, Davide; Mostacci, Domiziano; Marengo, Mario

    2015-12-01

    In a medical cyclotron facility, (41)Ar (t1/2 = 109.34 m) is produced by the activation of air due to the neutron flux during irradiation, according to the (40)Ar(n,γ)(41)Ar reaction; this is particularly relevant in widely diffused high beam current cyclotrons for the production of PET radionuclides. While theoretical estimations of the (41)Ar production have been published, no data are available on direct experimental measurements for a biomedical cyclotron. In this work, we describe a sampling methodology and report the results of an extensive measurement campaign. Furthermore, the experimental results are compared with Monte Carlo simulations performed with the FLUKA code. To measure (41)Ar activity, air samples were taken inside the cyclotron bunker in sealed Marinelli beakers, during the routine production of (18)F with a 16.5 MeV GE-PETtrace cyclotron; this sampling thus reproduces a situation of absence of air changes. Samples analysis was performed in a gamma-ray spectrometry system equipped with HPGe detector. Monte Carlo assessment of the (41)Ar saturation yield was performed directly using the standard FLUKA score RESNUCLE, and off-line by the convolution of neutron fluence with cross section data. The average (41)Ar saturation yield per one liter of air of (41)Ar, measured in gamma-ray spectrometry, resulted to be 3.0 ± 0.6 Bq/µA*dm(3) while simulations gave a result of 6.9 ± 0.3 Bq/µA*dm(3) in the direct assessment and 6.92 ± 0.22 Bq/µA*dm(3) by the convolution neutron fluence-to-cross section. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  3. CFD Prediction and Experimental Measurement of Blade Water Coverage in a Diesel Turbocharger

    Directory of Open Access Journals (Sweden)

    Jun Yao

    2012-01-01

    Full Text Available A turbocharger unit for diesel engine is often equipped with a built-in online water washing system and its performance is not always satisfactory because of efficiency declination due to deposit accumulated on blade surfaces not being washed away. In this study, a systematic approach of using experimental measurements and computational fluid dynamics (CFD is adopted to analyse liquid/gas two-phase flow associated with a turbocharger water washing system, in order to understand the underlying flow physics. A medium-sized diesel engine turbocharger configuration is chosen for this purpose. Experiments are focussed on blade surface temperature measurements, while CFD modelling with a coupled Eulerian/Lagrangian method is used for capturing the complex gas/liquid two-phase flow behaviours inside the induction duct and the blade passage. It was found that numerical predictions are in a good agreement with experimental data in terms of temperature distributions of the blade leading edge region and water coverage over the blade ring. Other flow features such as the water droplet trajectories and the particle size distributions are also explored and analysed in further details, and they are useful for understanding the deposit removal mechanism.

  4. In vivo measurement of intracellular pH in human brain during different tensions of carbon dioxide in arterial blood. A 31P-NMR study

    DEFF Research Database (Denmark)

    Jensen, K E; Thomsen, C; Henriksen, O

    1988-01-01

    The effect of changes in carbon dioxide tension in arterial blood upon intracellular pH in brain tissue was studied in seven healthy volunteers, aged 22-45 years. The pH changes were monitored by use of 31P nuclear magnetic resonance spectroscopy, performed on a whole-body 1.5 Tesla Siemens imaging...... system. The measurements were carried out during hyperventilation and with the subject breathing atmospheric air containing 5 vol. % and 7 vol. % carbon dioxide. Intracellular pH increased significantly during 15 min of hyper-ventilation and decreased significantly during 18 min respiration of air...

  5. Analysis of tissue bioimpedance as a measurement of liver steatosis: experimental model in large animals.

    Science.gov (United States)

    Gonzalo, M A; Martínez-Beamonte, R; Palacios, P; Marín, J; Castiella, T; Surra, J; Burdío, F; Sousa, R; Güemes, A; Osada, J; García-Gil, A

    2012-01-01

    Electrical bioimpedance (BI) has been used to indirectly measure steatosis. This method has not yet been established in the clinics thus experimental studies are needed in big animals. We assessed BI to measure liver steatosis in porcine animals. Twelve large-white × Landrace pigs weighing 35 kg were allocated to a study (n = 9) and a control group (n = 3). A special diet was used to promote steatosis among the study group: methionine deficient and choline-restricted diet that contains supplements of cholesterol, collate and excess of saturated fat. Control group animals were fed a normal diet. A new tetrapolar electrode model was used for BI measurement, which were performed during open laparotomy by inserting a probe into one of the lobes. Measurements were done in the third and fourth segments of the pig liver, placing the probe either on the surface or inserted into the parenchyma of the liver. Open biopsies were obtained at the end of the measurements. Histological samples were processed and stained with hematoxylin-eosin to estimate macrosteatosis. Pearson correlation coefficient between BI and percentage steatosis were calculated at different frequencies. After 4 months of the special diet all the animals in the study group developed steatosis (90% to 20%), whereas none of the control group was affected. Pearson correlation coefficients between BI and percentage of steatosis were significant (0.877-0.878) with the best correlations obtained with a probe placed on the fourth segment of the liver surface and the best frequency to perform the measurements being 50 and 75 kHz. BI is an accurate, fast method for steatosis measurements, that is easier and cheaper than either open or needle biopsy. Copyright © 2012. Published by Elsevier Inc.

  6. Comparison of blood velocity measurements between ultrasound Doppler and accelerated phase-contrast MR angiography in small arteries with disturbed flow

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Jingfeng; Johnson, Kevin; Wieben, Oliver; Zagzebski, James [Medical Physics Department, University of Wisconsin-Madison School of Medicine and Public Health, WI (United States); Strother, Charles; Consigny, Dan [Radiology Department, University of Wisconsin-Madison School of Medicine and Public Health, WI (United States); Baker, Sara, E-mail: jjiang2@wisc.edu [School of Ultrasound, University of Wisconsin-Madison School of Medicine and Public Health, WI (United States)

    2011-03-21

    Ultrasound Doppler (UD) velocity measurements are commonly used to quantify blood flow velocities in vivo. The aim of our work was to investigate the accuracy of in vivo spectral Doppler measurements of velocity waveforms. Waveforms were derived from spectral Doppler signals and corrected for intrinsic spectral broadening errors by applying a previously published algorithm. The method was tested in a canine aneurysm model by determining velocities in small arteries (3-4 mm diameter) near the aneurysm where there was moderately disturbed flow. Doppler results were compared to velocity measurements in the same arteries acquired with a rapid volumetric phase contrast MR angiography technique named phase contrast vastly undersampled isotropic projection reconstruction magnetic resonance angiography (PC-VIPR MRA). After correcting for intrinsic spectral broadening, there was a high degree of correlation between velocities obtained by the real-time UD and the accelerated PC-MRA technique. The peak systolic velocity yielded a linear correlation coefficient of r = 0.83, end diastolic velocity resulted in r = 0.81, and temporally averaged mean velocity resulted in r = 0.76. The overall velocity waveforms obtained by the two techniques were also highly correlated (r = 0.89 {+-} 0.06). There were, however, only weak correlations for the pulsatility index (PI: 0.25) and resistive index (RI: 0.14) derived from the two techniques. Results demonstrate that to avoid overestimations of peak systolic velocities, the results for UD must be carefully corrected to compensate for errors caused by intrinsic spectral broadening.

  7. Comparison of blood velocity measurements between ultrasound Doppler and accelerated phase-contrast MR angiography in small arteries with disturbed flow

    Science.gov (United States)

    Jiang, Jingfeng; Strother, Charles; Johnson, Kevin; Baker, Sara; Consigny, Dan; Wieben, Oliver; Zagzebski, James

    2011-03-01

    Ultrasound Doppler (UD) velocity measurements are commonly used to quantify blood flow velocities in vivo. The aim of our work was to investigate the accuracy of in vivo spectral Doppler measurements of velocity waveforms. Waveforms were derived from spectral Doppler signals and corrected for intrinsic spectral broadening errors by applying a previously published algorithm. The method was tested in a canine aneurysm model by determining velocities in small arteries (3-4 mm diameter) near the aneurysm where there was moderately disturbed flow. Doppler results were compared to velocity measurements in the same arteries acquired with a rapid volumetric phase contrast MR angiography technique named phase contrast vastly undersampled isotropic projection reconstruction magnetic resonance angiography (PC-VIPR MRA). After correcting for intrinsic spectral broadening, there was a high degree of correlation between velocities obtained by the real-time UD and the accelerated PC-MRA technique. The peak systolic velocity yielded a linear correlation coefficient of r = 0.83, end diastolic velocity resulted in r = 0.81, and temporally averaged mean velocity resulted in r = 0.76. The overall velocity waveforms obtained by the two techniques were also highly correlated (r = 0.89 ± 0.06). There were, however, only weak correlations for the pulsatility index (PI: 0.25) and resistive index (RI: 0.14) derived from the two techniques. Results demonstrate that to avoid overestimations of peak systolic velocities, the results for UD must be carefully corrected to compensate for errors caused by intrinsic spectral broadening.

  8. Design of an experimental apparatus for measurement of the surface tension of metastable fluids

    Directory of Open Access Journals (Sweden)

    Blaha J.

    2013-04-01

    Full Text Available A unique experimental apparatus for measurement of the surface tension of aqueous mixtures has been designed, manufactured, and tested in our laboratory. The novelty of the setup is that it allows measurement of surface tension by two different methods: a modified capillary elevation method in a long vertical capillary tube and a method inspired by the approach of Hacker (National Advisory Committee for Aeronautics, Technical Note 2510, 1-20, 1951, i.e. in a short horizontal capillary tube. Functionality of all main components of the apparatus, e.g., glass chamber with the capillary tube, temperature control unit consisting of two thermostatic baths with special valves for rapid temperature jumps, helium distribution setup allowing pressure variation above the liquid meniscus inside the capillary tube, has been successfully tested. Preliminary results for the surface tension of the stable and metastable supercooled water measured by the capillary elevation method at atmospheric pressure are provided. The surface tension of water measured at temperatures between +26 °C and –11 °C is in good agreement with the extrapolated IAPWS correlation (IAPWS Release on Surface Tension of Ordinary Water Substance, September 1994; however it disagrees with data by Hacker.

  9. A Wearable Thermometry for Core Body Temperature Measurement and Its Experimental Verification.

    Science.gov (United States)

    Huang, Ming; Tamura, Toshiyo; Tang, Zunyi; Chen, Wenxi; Kanaya, Shigehiko

    2017-05-01

    A wearable thermometry for core body temperature (CBT) measurement has both healthcare and clinical applications. On the basis of the mechanism of bioheat transfer, we earlier designed and improved a wearable thermometry using the dual-heat-flux method for CBT measurement. In this study, this thermometry is examined experimentally. We studied a fast-changing CBT measurement (FCCM, 55 min, 12 subjects) inside a thermostatic chamber and performed long-term monitoring of CBT (LTM, 24 h, six subjects). When compared with a reference, the CoreTemp CM-210 by Terumo, FCCM shows 0.07 °C average difference and a 95% CI of [-0.27, 0.12] °C. LTM shows no significant difference in parameters for the inference of circadian rhythm. The FCCM and LTM both simulated scenarios in which this thermometry could be used for intensive monitoring and daily healthcare, respectively. The results suggest that because of its convenient design, this thermometry may be an ideal choice for conventional CBT measurements.

  10. Design of an experimental apparatus for measurement of the surface tension of metastable fluids

    Science.gov (United States)

    Vinš, V.; Hrubý, J.; Hykl, J.; Blaha, J.; Šmíd, B.

    2013-04-01

    A unique experimental apparatus for measurement of the surface tension of aqueous mixtures has been designed, manufactured, and tested in our laboratory. The novelty of the setup is that it allows measurement of surface tension by two different methods: a modified capillary elevation method in a long vertical capillary tube and a method inspired by the approach of Hacker (National Advisory Committee for Aeronautics, Technical Note 2510, 1-20, 1951), i.e. in a short horizontal capillary tube. Functionality of all main components of the apparatus, e.g., glass chamber with the capillary tube, temperature control unit consisting of two thermostatic baths with special valves for rapid temperature jumps, helium distribution setup allowing pressure variation above the liquid meniscus inside the capillary tube, has been successfully tested. Preliminary results for the surface tension of the stable and metastable supercooled water measured by the capillary elevation method at atmospheric pressure are provided. The surface tension of water measured at temperatures between +26 °C and -11 °C is in good agreement with the extrapolated IAPWS correlation (IAPWS Release on Surface Tension of Ordinary Water Substance, September 1994); however it disagrees with data by Hacker.

  11. Correlation of experimentally measured atomic scale properties of EUV photoresist to modeling performance: an exploration

    Science.gov (United States)

    Kandel, Yudhishthir; Chandonait, Jonathan; Melvin, Lawrence S.; Marokkey, Sajan; Yan, Qiliang; Grzeskowiak, Steven; Painter, Benjamin; Denbeaux, Gregory

    2017-03-01

    Extreme ultraviolet (EUV) lithography at 13.5 nm stands at the crossroads of next generation patterning technology for high volume manufacturing of integrated circuits. Photo resist models that form the part of overall pattern transform model for lithography play a vital role in supporting this effort. The physics and chemistry of these resists must be understood to enable the construction of accurate models for EUV Optical Proximity Correction (OPC). In this study, we explore the possibility of improving EUV photo-resist models by directly correlating the parameters obtained from experimentally measured atomic scale physical properties; namely, the effect of interaction of EUV photons with photo acid generators in standard chemically amplified EUV photoresist, and associated electron energy loss events. Atomic scale physical properties will be inferred from the measurements carried out in Electron Resist Interaction Chamber (ERIC). This study will use measured physical parameters to establish a relationship with lithographically important properties, such as line edge roughness and CD variation. The data gathered from these measurements is used to construct OPC models of the resist.

  12. Threshold-dependent variability of coronary artery calcification measurements - implications for contrast-enhanced multi-detector row-computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Moselewski, Fabian [Division of Cardiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Ferencik, Maros [Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Achenbach, Stephan [Division of Cardiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Department of Internal Medicine II (Cardiology), University of Erlangen (Germany); Abbara, Suhny [Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Cury, Ricardo C. [Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Booth, Sarah L. [Jean Mayer USDA Human Nutrition Research Center on Aging, 711 Washington St., Boston, MA 02114 (United States); Jang, Ik-Kyung [Division of Cardiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Brady, Thomas J. [Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Hoffmann, Udo [Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States)]. E-mail: uhoffman@partners.org

    2006-03-15

    Introduction: The present study investigated the threshold-dependent variability of coronary artery calcification (CAC) measurements and the potential to quantify CAC in contrast-enhanced multi-detector row-computed tomography (MDCT). Methods: We compared the mean CT attenuation of CAC to luminal contrast enhancement of the coronary arteries in 30 patients (n = 30) undergoing standard coronary contrast-enhanced spiral MDCT. The modified Agatston score [AS], calcified plaque volume [CV], and mineral mass [MM] at four different thresholds (130, 200, 300, and 400 HU) were measured in 50 patients who underwent non-contrast-enhanced MDCT. Results: Mean CT attenuation of CAC was similar to the attenuation of the contrast-enhanced coronary lumen (CAC 297.1 {+-} 68.7 HU versus 295 {+-} 65 HU (p < 0.0001), respectively). Above a threshold of 300 HU CAC measurements significantly varied to standard measurements obtained at a threshold of 130 HU (p < 0.0001). The threshold-dependent variation of MM measurements was significantly smaller than for AS and CV (130 HU versus 400 HU: 63, 75, and 81, respectively; p < 0.001). These differences resulted in a change of age and gender based percentile category for AS in 78% of subjects. Discussion: We demonstrated that CAC measurements are threshold dependent with MM measurements having significantly less variation than AS or CV. Due to the similarity of mean CT attenuation of CAC and the contrast-enhanced coronary lumen accurate quantification of CAC may be difficult in standard coronary contrast-enhanced spiral MDCT.

  13. Which cardiovascular magnetic resonance planes and sequences provide accurate measurements of branch pulmonary artery size in children with right ventricular outflow tract obstruction?

    Science.gov (United States)

    Vijarnsorn, Chodchanok; Rutledge, Jennifer M; Tham, Edythe B; Coe, James Y; Quinonez, Luis; Patton, David J; Noga, Michelle

    2014-02-01

    Children with right ventricular outflow tract obstructive (RVOTO) lesions require precise quantification of pulmonary artery (PA) size for proper management of branch PA stenosis. We aimed to determine which cardiovascular magnetic resonance (CMR) sequences and planes correlated best with cardiac catheterization and surgical measurements of branch PA size. Fifty-five children with RVOTO lesions and biventricular circulation underwent CMR prior to; either cardiac catheterization (n = 30) or surgery (n = 25) within a 6 month time frame. CMR sequences included axial black blood, axial, coronal oblique and sagittal oblique cine balanced steady-state free precession (bSSFP), and contrast-enhanced magnetic resonance angiography (MRA) with multiplanar reformatting in axial, coronal oblique, sagittal oblique, and cross-sectional planes. Maximal branch PA and stenosis (if present) diameter were measured. Comparisons of PA size on CMR were made to reference methods: (1) catheterization measurements performed in the anteroposterior plane at maximal expansion, and (2) surgical measurement obtained from a maximal diameter sound which could pass through the lumen. The mean differences (Δ) and intra class correlation (ICC) were used to determine agreement between different modalities. CMR branch PA measurements were compared to the corresponding cardiac catheterization measurements in 30 children (7.6 ± 5.6 years). Reformatted MRA showed better agreement for branch PA measurement (ICC > 0.8) than black blood (ICC 0.4-0.6) and cine sequences (ICC 0.6-0.8). Coronal oblique MRA and maximal cross sectional MRA provided the best correlation of right PA (RPA) size with ICC of 0.9 (Δ -0.1 ± 2.1 mm and Δ 0.5 ± 2.1 mm). Maximal cross sectional MRA and sagittal oblique MRA provided the best correlate of left PA (LPA) size (Δ 0.1 ± 2.4 and Δ -0.7 ± 2.4 mm). For stenoses, the best correlations were from coronal oblique MRA of right pulmonary artery (RPA) (Δ -0.2 ± 0.8 mm, ICC 0

  14. Calculation of the Scattered Radiation Profile in 64 Slice CT Scanners Using Experimental Measurement

    Directory of Open Access Journals (Sweden)

    Afshin Akbarzadeh

    2009-06-01

    Full Text Available Introduction: One of the most important parameters in x-ray CT imaging is the noise induced by detected scattered radiation. The detected scattered radiation is completely dependent on the scanner geometry as well as size, shape and material of the scanned object. The magnitude and spatial distribution of the scattered radiation in x-ray CT should be quantified for development of robust scatter correction techniques. Empirical methods based on blocking the primary photons in a small region are not able to extract scatter in all elements of the detector array while the scatter profile is required for a scatter correction procedure. In this study, we measured scatter profiles in 64 slice CT scanners using a new experimental measurement. Material and Methods: To measure the scatter profile, a lead block array was inserted under the collimator and the phantom was exposed at the isocenter. The raw data file, which contained detector array readouts, was transferred to a PC and was read using a dedicated GUI running under MatLab 7.5. The scatter profile was extracted by interpolating the shadowed area. Results: The scatter and SPR profiles were measured. Increasing the tube voltage from 80 to 140 kVp resulted in an 80% fall off in SPR for a water phantom (d=210 mm and 86% for a polypropylene phantom (d = 350 mm. Increasing the air gap to 20.9 cm caused a 30% decrease in SPR. Conclusion: In this study, we presented a novel approach for measurement of scattered radiation distribution and SPR in a CT scanner with 64-slice capability using a lead block array. The method can also be used on other multi-slice CT scanners. The proposed technique can accurately estimate scatter profiles. It is relatively straightforward, easy to use, and can be used for any related measurement.

  15. Turbulence intensity measurements using particle image velocimetry in diseased carotid artery models: effect of stenosis severity, plaque eccentricity, and ulceration.

    Science.gov (United States)

    Kefayati, Sarah; Holdsworth, David W; Poepping, Tamie L

    2014-01-03

    Clinical decision-making for the treatment of patients with diseased carotid artery is mainly based on the severity of the stenosis. However, stenosis severity alone is not a sensitive indicator, and other local factors for the assessment of stroke risk are required. Flow disturbance is of particular interest due to its proven association with increased thromboembolic activities. The objective of this study was to investigate the level of turbulence intensity (TI) with regards to certain geometrical features of the plaque - namely stenosis severity, eccentricity, and ulceration. A family of eight carotid-artery bifurcation models was examined using particle image velocimetry. Results showed a marked difference in turbulence intensity among these models; increasing degree of stenosis severity resulted in increased turbulence intensity, going from 0.12 m/s for mild stenosis to 0.37 m/s for severe stenosis (with concentric geometry). Moreover, independent of stenosis severity, eccentricity led to further elevations in turbulence intensity, increasing TI by 0.05-0.10 m/s over the counterpart concentric plaque. The presence of ulceration (in a 50% eccentric plaque) produced a larger portion of moderate turbulence intensity (~0.10 m/s) compared to the non-ulcerated model, more proximal to the bifurcation apex in the post-stenotic recirculation zone. The effect of plaque eccentricity and ulceration in enhancing the downstream turbulence has potential clinical implications for a more sensitive assessment of stroke risk beyond stenosis severity alone. © 2013 Elsevier Ltd. All rights reserved.

  16. Impact of hyperaemic microvascular resistance on fractional flow reserve measurements in patients with stable coronary artery disease: insights from combined stenosis and microvascular resistance assessment.

    Science.gov (United States)

    van de Hoef, Tim P; Nolte, Froukje; EchavarrÍa-Pinto, Mauro; van Lavieren, Martijn A; Damman, Peter; Chamuleau, Steven A J; Voskuil, Michiel; Verberne, Hein J; Henriques, José P S; van Eck-Smit, Berthe L F; Koch, Karel T; de Winter, Robbert J; Spaan, Jos A E; Siebes, Maria; Tijssen, Jan G P; Meuwissen, Martijn; Piek, Jan J

    2014-06-01

    Fractional flow reserve (FFR) aims to identify the extent of epicardial disease, but may be obscured by involvement of the coronary microvasculature. We documented the impact of hyperaemic stenosis resistance (HSR) and hyperaemic microvascular resistance (HMR) on FFR, and its relationship with myocardial ischaemia in patients with stable coronary artery disease. We evaluated 255 coronary arteries with stenoses of intermediate severity by means of intracoronary pressure and flow measurements to determine FFR, HSR and HMR. Myocardial perfusion scintigraphy (MPS) was performed to identify inducible myocardial ischaemia. In 178 patients, HMR was additionally determined in a reference coronary artery. Target vessel HMR was stratified according to reference vessel HMR tertiles. The diagnostic OR for inducible ischaemia on MPS of a positive compared with a negative FFR was significantly higher only in the presence of a high HMR (at the 0.75 and 0.80 FFR cut-off). Among stenoses with a positive FFR, the prevalence of ischaemia was significantly higher when HMR was high despite equivalent FFR across the HMR groups. This was paralleled by a concomitant significant increase in HSR with increasing HMR across groups. The relation between FFR and HSR (r(2)=0.54, pdisease of equivalent severity, FFR increased with increasing HMR. Identification of epicardial disease severity by FFR is partly obscured by the microvascular resistance, which illustrates the necessity of combined pressure and flow measurements in daily practice. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  17. Arterial responses during migraine headache

    DEFF Research Database (Denmark)

    Iversen, Helle Klingenberg; Nielsen, T H; Olesen, J

    1990-01-01

    The superficial temporal artery has been thought to be the main focus of pain during migraine attacks, but its diameter has never been measured directly. The use of a new, high-resolution ultrasound machine to measure arterial size in 25 migraine patients with unilateral head pain showed...... that the lumen was wider on the painful than on the non-painful side during a migraine attack. The diameters of both radial arteries and the temporal artery on the non-painful side were smaller during than between attacks. The generalised vasoconstriction was not shared by the temporal artery on the affected...... side, which suggests a local vasodilatory response. The findings suggest that cephalic arteries may play a role in migraine pathogenesis....

  18. Coronary Artery Bypass Grafting

    Science.gov (United States)

    ... Health Topics / Coronary Artery Bypass Grafting Coronary Artery Bypass Grafting What Is Coronary artery bypass grafting (CABG) ... multiple coronary arteries during one surgery. Coronary Artery Bypass Grafting Figure A shows the location of the ...

  19. Monte Carlo and experimental determination of correction factors for gamma knife perfexion small field dosimetry measurements

    Science.gov (United States)

    Zoros, E.; Moutsatsos, A.; Pappas, E. P.; Georgiou, E.; Kollias, G.; Karaiskos, P.; Pantelis, E.

    2017-09-01

    Detector-, field size- and machine-specific correction factors are required for precise dosimetry measurements in small and non-standard photon fields. In this work, Monte Carlo (MC) simulation techniques were used to calculate the k{{Qmsr},{{Q}0}}{{fmsr},{{f}ref}} and k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} correction factors for a series of ionization chambers, a synthetic microDiamond and diode dosimeters, used for reference and/or output factor (OF) measurements in the Gamma Knife Perfexion photon fields. Calculations were performed for the solid water (SW) and ABS plastic phantoms, as well as for a water phantom of the same geometry. MC calculations for the k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} correction factors in SW were compared against corresponding experimental results for a subset of ionization chambers and diode detectors. Reference experimental OF data were obtained through the weighted average of corresponding measurements using TLDs, EBT-2 films and alanine pellets. k{{Qmsr},{{Q}0}}{{fmsr},{{f}ref}} values close to unity (within 1%) were calculated for most of ionization chambers in water. Greater corrections of up to 6.0% were observed for chambers with relatively large air-cavity dimensions and steel central electrode. A phantom correction of 1.006 and 1.024 (breaking down to 1.014 from the ABS sphere and 1.010 from the accompanying ABS phantom adapter) were calculated for the SW and ABS phantoms, respectively, adding up to k{{Qmsr},{{Q}0}}{{fmsr},{{f}ref}} corrections in water. Both measurements and MC calculations for the diode and microDiamond detectors resulted in lower than unit k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} correction factors, due to their denser sensitive volume and encapsulation materials. In comparison, higher than unit k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} results for the ionization chambers suggested field size depended dose underestimations (being significant for the 4 mm field), with magnitude depending on the combination of

  20. Experimental measurement and CFD simulation on the hydrodynamics of an internal-loop airlift reactor

    Directory of Open Access Journals (Sweden)

    Liew Shi Yan

    2017-01-01

    Full Text Available This paper concerns with the experimental measurement and computational fluid dynamics simulation on local hydrodynamics of a gas-liquid internal-loop airlift reactor. The aim of this work is to study the sensitivity of the drag models and the significance of considering the lift force on the predictive accuracy of the simulation. The experimental analysis was carried out using laser Doppler anemometry at three different heights (i.e. Y = 0.20 m, 0.30 m and 0.38 m across the riser and downcomerat volumetric flow rate of 0.30 m3/h to provide validation for the simulation results. A transient three-dimensional gasliquid internal-loop airlift reactor was carried out using FLUENT 16.2 by implementing the two-fluid model approach. The Eulerian-Eulerian multiphase and standard κ-ε dispersed turbulence model wereemployed in this study. Results suggest that the spherical drag model performed poorly and that the drag model governed by Rayleigh-Taylor shows promising accuracy in the prediction of overall mean axial liquid velocity. On the other hand, the consideration of lift model shows slightly improvement in accuracy. These findings may serve as a guidance for future scale-up and design of airlift reactor studies

  1. An Experimental Comparison of Similarity Assessment Measures for 3D Models on Constrained Surface Deformation

    Science.gov (United States)

    Quan, Lulin; Yang, Zhixin

    2010-05-01

    To address the issues in the area of design customization, this paper expressed the specification and application of the constrained surface deformation, and reported the experimental performance comparison of three prevail effective similarity assessment algorithms on constrained surface deformation domain. Constrained surface deformation becomes a promising method that supports for various downstream applications of customized design. Similarity assessment is regarded as the key technology for inspecting the success of new design via measuring the difference level between the deformed new design and the initial sample model, and indicating whether the difference level is within the limitation. According to our theoretical analysis and pre-experiments, three similarity assessment algorithms are suitable for this domain, including shape histogram based method, skeleton based method, and U system moment based method. We analyze their basic functions and implementation methodologies in detail, and do a series of experiments on various situations to test their accuracy and efficiency using precision-recall diagram. Shoe model is chosen as an industrial example for the experiments. It shows that shape histogram based method gained an optimal performance in comparison. Based on the result, we proposed a novel approach that integrating surface constrains and shape histogram description with adaptive weighting method, which emphasize the role of constrains during the assessment. The limited initial experimental result demonstrated that our algorithm outperforms other three algorithms. A clear direction for future development is also drawn at the end of the paper.

  2. An Experimental Method for Measuring Water Droplet Impingement Efficiency on Two- and Three-dimensional Bodies

    Science.gov (United States)

    Papadakis, M.; Zumwalt, G. W.; Elangonan, R.; Freund, G. A., Jr.; Breer, M.; Whitmer, L.

    1989-01-01

    An experimental method was developed to determine the droplet impingement characteristics on 2-D and 3-D bodies. The experimental results provide the essential droplet impingement data required to validate water droplet trajectory codes, which are used in the analysis of aircraft icing. A body, whose water droplet impingement characteristics are required, is covered at strategic locations by thin strips of moisture absorbing (blotter) paper, and is exposed to an air stream containing a water dye solution spray cloud. Water droplet impingement data are extracted from the dyed blotter strips by measuring the optical reflectance of the dye deposit on the strips, using an automated reflectometer. Models tested include a 4-inch diameter cylinder, a NACA 652015 airfoil section, a MS(1)-0317 supercritical airfoil section, three simulated ice shapes, an axisymmetric inlet and a Boeing 737-300 inlet model. Detailed descriptions of the dye tracer technique, instrumentation, data reduction method and the results obtained are presented. Analytical predictions of collection efficiency characteristics for most test configurations are included for comparison.

  3. Measuring the Biodegradability of Plastic Polymers in Olive-Mill Waste Compost with an Experimental Apparatus

    Directory of Open Access Journals (Sweden)

    Francesco Castellani

    2016-01-01

    Full Text Available The use of biodegradable polymers is spreading in agriculture to replace those materials derived from petroleum, thus reducing the environmental concerns. However, to issue a significant assessment, biodegradation rate must be measured in case-specific standardized conditions. In accordance with ISO 14855-1, we designed and used an experimental apparatus to evaluate the biodegradation rate of three biopolymers based on renewable resources, two poly(ε-caprolactone (PCL composites, and a compatibilized polylactic acid and polybutyrate (PLA/PBAT blend. Biodegradation tests were carried out under composting condition using mature olive-mill waste (OMW compost as inoculum. Carbon dioxide emissions were automatically recorded by infrared gas detectors and also trapped in saturated Ba(OH2 solution and evaluated via a standard titration method to check the results. Some of the samples reached more than 80% biodegradation in less than 20 days. Both the experimental apparatus and the OMW compost showed to be suitable for the cases studied.

  4. Fluid dynamic design and experimental study of an aspirated temperature measurement platform used in climate observation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jie, E-mail: yangjie396768@163.com [Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing 210044 (China); School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Liu, Qingquan [Jiangsu Key Laboratory of Meteorological Observation and Information Processing, Nanjing 210044 (China); Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment Technology, Nanjing 210044 (China); Dai, Wei [School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Ding, Renhui [Jiangsu Meteorological Observation Center, Nanjing 210008 (China)

    2016-08-15

    Due to the solar radiation effect, current air temperature sensors inside a thermometer screen or radiation shield may produce measurement errors that are 0.8 °C or higher. To improve the observation accuracy, an aspirated temperature measurement platform is designed. A computational fluid dynamics (CFD) method is implemented to analyze and calculate the radiation error of the aspirated temperature measurement platform under various environmental conditions. Then, a radiation error correction equation is obtained by fitting the CFD results using a genetic algorithm (GA) method. In order to verify the performance of the temperature sensor, the aspirated temperature measurement platform, temperature sensors with a naturally ventilated radiation shield, and a thermometer screen are characterized in the same environment to conduct the intercomparison. The average radiation errors of the sensors in the naturally ventilated radiation shield and the thermometer screen are 0.44 °C and 0.25 °C, respectively. In contrast, the radiation error of the aspirated temperature measurement platform is as low as 0.05 °C. This aspirated temperature sensor allows the radiation error to be reduced by approximately 88.6% compared to the naturally ventilated radiation shield, and allows the error to be reduced by a percentage of approximately 80% compared to the thermometer screen. The mean absolute error and root mean square error between the correction equation and experimental results are 0.032 °C and 0.036 °C, respectively, which demonstrates the accuracy of the CFD and GA methods proposed in this research.

  5. Experimental validation of a technique to measure tilt from a laser guide star.

    Science.gov (United States)

    Belen'kii, M S; Karis, S J; Brown, J M; Fugate, R Q

    1999-05-15

    We have experimentally demonstrated for what is believed to be the first time a method for sensing wave-front tilt with a laser guide star (LGS). The tilt components of wave fronts were measured synchronously from the LGS by use of a telescope with a 0.75-m effective aperture and from the star Polaris by use of a 1.5-m telescope. The Rayleigh guide star was formed at an altitude of 6 km and at a corresponding range of 10.5 km by projection of a focused beam at Polaris from the full aperture at the 1.5-m telescope. Both telescope mounts were unpowered and bolted in place, allowing us to reduce substantially the telescope vibration. The maximum value of the measured cross-correlation coefficient between the tilt for Polaris and the LGS is 0.71. The variations of the measured cross-correlation coefficient in the range from 0.22 to 0.71 are caused by turbulence at altitudes above 6 km, which was not sampled by the laser beacon but affected tilt for Polaris, the cone effect for turbulence below 6 km, residual mount jitter of the telescopes, and variations of the signal/noise ratio. The results support our concept of sensing atmospheric tilt by observing a LGS with an auxiliary telescope and indicate that this method is a possible solution for the tip-tilt problem.

  6. Experimental measurements on a powder avalanche impacting an obstacle: 3D velocity field and exerted pressures

    Science.gov (United States)

    Caccamo, P.; Naaim-Bouvet, F.; Bellot, H.; Ousset, F.; Faug, T.

    2012-04-01

    In the framework of the Alcotra DYNAVAL Interreg project, this experimental study aims at investigating the dynamical behaviour of a powder snow avalanche impacting an obstacle. Tests have been realised in a water tank where a salty water solution (rho=1.2kg m-3) flows down in a channel and impacts an obstacle at a distance d=1m from the releasing gate. The set-up geometry reproduces a simplified small-scale model of the real avalanche site of Taconnaz (Chamonix, France). A high-resolution acoustic velocimeter allows measurements on the 3D flow velocity. By measuring the velocity just upstream and downstream of the obstacle, it is possible to determine the influence of the obstacle on the flow. In a lack of suitable sensors, the pressure exerted on the obstacle is calculated using the classical formula P=1/2rhoU2. Then, density values are required. A new method to measure the flow density is advanced and preliminary results are presented.

  7. Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials.

    Science.gov (United States)

    Hagmann, Joseph A; Le, Son T; Richter, Curt A; Seiler, David G

    2016-01-21

    Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film synthesis) for the purpose of exploratory materials research. Certain materials pose a challenge wherein the traditional bulk Hall bar device fabrication method is insufficient to produce a measureable device for sample transport measurement, principally because the single crystal size is too small to attach wire leads to the sample in a Hall bar configuration. This can be, for example, because the first batch of a new material synthesized yields very small single crystals or because flakes of samples of one to very few monolayers are desired. In order to enable rapid characterization of materials that may be carried out in parallel with improvements to their growth methodology, a method of device fabrication for very small samples has been devised to permit the characterization of novel materials as soon as a preliminary batch has been produced. A slight variation of this methodology is applicable to producing devices using exfoliated samples of two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDs), as well as multilayer heterostructures of such materials. Here we present detailed protocols for the experimental device fabrication of fragments and flakes of novel materials with micron-sized dimensions onto substrate and subsequent measurement in a commercial superconducting magnet, dry helium close-cycle cryostat magnetotransport system at temperatures down to 0.300 K and magnetic fields up to 12 T.

  8. Experimental investigation of near-wall effects on hot-wire measurements

    Energy Technology Data Exchange (ETDEWEB)

    Durst, F.; Zanoun, E.S. [Institute of Fluid Mechanics, Friedrich-Alexander-University, Erlangen-Nuernberg Cauerstr. 4, 91058 Erlangen (Germany)

    2002-07-01

    Hot-wire anemometry is a well-established measuring technique in modern fluid mechanics and is widely used to study laminar and turbulent flows. However, unsolved problems still exist when measurements are carried out close to heat-conducting or heat-insulating walls. Additional heat losses occur because of the presence of the wall that are usually not accounted for in the calibration of the wire. Because of this, erroneous fluid velocity measurements result with hot wires if the presence of the wall is not taken into account. The present paper investigates the effect that the wall material has on these additional heat losses from hot wires for walls of different heat conductivities. Similarity analysis of various aspects of the problem, verified by experimental and numerical results, is presented for wall materials of different heat conductivities, and the results are compared with available data in the literature. The data confirm the expected increase in heat losses with increasing wall heat conductivity. For heat-insulating materials the authors' results show that a wall-thickness influence exists. Additional data are provided to show that the heat loss from hot wires increases with increasing wire overheating, and the influence of the wire diameter is also clarified. (orig.)

  9. Time-Resolved In Situ Measurements During Rapid Alloy Solidification: Experimental Insight for Additive Manufacturing

    Science.gov (United States)

    McKeown, Joseph T.; Zweiacker, Kai; Liu, Can; Coughlin, Daniel R.; Clarke, Amy J.; Baldwin, J. Kevin; Gibbs, John W.; Roehling, John D.; Imhoff, Seth D.; Gibbs, Paul J.; Tourret, Damien; Wiezorek, Jörg M. K.; Campbell, Geoffrey H.

    2016-03-01

    Additive manufacturing (AM) of metals and alloys is becoming a pervasive technology in both research and industrial environments, though significant challenges remain before widespread implementation of AM can be realized. In situ investigations of rapid alloy solidification with high spatial and temporal resolutions can provide unique experimental insight into microstructure evolution and kinetics that are relevant for AM processing. Hypoeutectic thin-film Al-Cu and Al-Si alloys were investigated using dynamic transmission electron microscopy to monitor pulsed-laser-induced rapid solidification across microsecond timescales. Solid-liquid interface velocities measured from time-resolved images revealed accelerating solidification fronts in both alloys. The observed microstructure evolution, solidification product, and presence of a morphological instability at the solid-liquid interface in the Al-4 at.%Cu alloy are related to the measured interface velocities and small differences in composition that affect the thermophysical properties of the alloys. These time-resolved in situ measurements can inform and validate predictive modeling efforts for AM.

  10. Precise measurement of the HFS of positronium using the zeeman effect I: Experimental set-up and RF system

    Energy Technology Data Exchange (ETDEWEB)

    Akimoto, G; Ishida, A; Sasaki, Y; Miyazaki, A; Kato, K; Asai, S [Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan); Suehara, T; Namba, T; Kobayashi, T [International Center for Elementary Particle Physics (ICEPP), University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan); Saito, H [Department of General Systems Studies, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902 (Japan); Yoshida, M; Tanaka, K; Yamamoto, A [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801 (Japan); Urushizaki, Y; Ogawa, I; Idehara, T [Research Center for Development of Far-Infrared Region (FIR-FU), University of Fukui, 3-9-1 Bunkyo, Fukui, Fukui, 910-8507 (Japan); Sabchevski, S, E-mail: akimoto@icepp.s.u-tokyo.ac.j [Bulgarian Academy of Science, 1, 15 Noemvri Str, 1040 Sofia (Bulgaria)

    2010-04-01

    Positronium is a QCD-free system and the measurement of its hyperfine splitting provides a strict test of quantum electrodynamics (QED). Recent research revealed a discrepancy of 3.9{sigma} between the QED prediction and previous experimental results. We report on the prototype run of an improved experimental set-up and the performance of its RF system.

  11. Experimental and theoretical aspects of glucose measurement using a microcantilever modified by enzyme-containing polyacrylamide.

    Science.gov (United States)

    Ji, Hai-Feng; Yan, Xiaodong; McShane, Michael J

    2005-12-01

    We report a glucose oxidase-containing polyacrylamide hydrogel-coated microcantilever sensor for the measurement of glucose. This enzymatic reaction of glucose results in swelling of the hydrogel due to formation of charged ions (gluconate molecules and protons). The microcantilever undergoes reversible and reproducible bending deflection upon exposure to solutions containing various glucose concentrations due to swelling or shrinking of the hydrogels. The microcantilever deflections increase when the glucose concentrations increase. A theoretical model has been built to correlate volume changes of the gel with microcantilever bending. The calculated data matched with the experimental results very well. Such hydrogel-coated microcantilevers could potentially be used to prepare microcantilever-based chemical and biological sensors when other enzymes are immobilized in the hydrogel.

  12. Experimental testing of the digital multichannel analyzer for gamma spectrometry measurements

    Directory of Open Access Journals (Sweden)

    Novković Dušan

    2008-01-01

    Full Text Available The results of experimental testing of the digital multichannel analyzer which digitalizes the signal after a preamplifier are presented. The recordings of some of the characteristics of the spectrometer containing a digital MCA, such as full-peak efficiency, net area ratio of the two peaks and the stability of the peak position, were carried out under different input counting rates, with different radioactive sources. The tested MCA has shown some excellent features, like the stability of the peak position over a long-term period and flexibility in the adjusting of optimum measurement conditions. However, the performed tests have also shown some serious and unexpected disadvantages of the digital MCA when it operates under certain circumstances, one of them having to do with the automatic tuning of live-time correction at low-input counting rates.

  13. Experimental and mumerical validation of the technique for concrete cure monitoring using piezoelectric admittance measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Wan Cheol; Park, Gyu Hae [Dept. of Mechanical Engineering, Chonnam National University, Gwangju (Korea, Republic of)

    2016-06-15

    This paper presents a new technique for monitoring the concrete curing process using embedded piezoelectric transducers via admittance measurements. When a piezoelectric transducer is embedded in a structure, the electrical impedance (admittance) of the transducer is coupled with the mechanical impedance of the host structure, which allows monitoring of the structural condition. In this study, the admittance signatures are used for monitoring the concrete curing process. This new method is based on an admittance-based sensor diagnostic process, in which the capacitance values of the piezoelectric transducers are dependent on the strength of the host structure. We numerically and experimentally investigated the variations in capacitive value during the curing process. The results demonstrate that there is a clear relationship between the concrete curing status and the slope, this indicates that the proposed method could be efficiently used for monitoring the curing status of a concrete structure.

  14. Measuring incremental changes in word knowledge: experimental validation and implications for learning and assessment.

    Science.gov (United States)

    Frishkoff, Gwen A; Collins-Thompson, Kevyn; Perfetti, Charles A; Callan, Jamie

    2008-11-01

    The goal of this study was to test a new technique for assessing vocabulary development. This technique is based on an algorithm for scoring the accuracy of word definitions using a continuous scale (Collins-Thompson & Callan, 2007). In an experiment with adult learners, target words were presented in six different sentence contexts, and the number of informative versus misleading contexts was systematically manipulated. Participants generated a target definition after each sentence, and the definition-scoring algorithm was used to assess the degree of accuracy on each trial. We observed incremental improvements in definition accuracy across trials. Moreover, learning curves were sensitive to the proportion of misleading contexts, the use of spaced versus massed practice, and individual differences, demonstrating the utility of this procedure for capturing specific experimental effects on the trajectory of word learning. We discuss the implications of these results for measurement of meaning, vocabulary assessment, and instructional design.

  15. Design, Specification and Construction of Specialized Measurement System in the Experimental Building

    Science.gov (United States)

    Fedorczak-Cisak, Malgorzata; Kwasnowski, Pawel; Furtak, Marcin; Hayduk, Grzegorz

    2017-10-01

    Experimental buildings for “in situ” research are a very important tool for collecting data on energy efficiency of the energy-saving technologies. One of the most advanced building of this type in Poland is the Maloposkie Laboratory of Energy-saving Buildings at Cracow University of Technology. The building itself is used by scientists as a research object and research tool to test energy-saving technologies. It is equipped with a specialized measuring system consisting of approx. 3 000 different sensors distributed in technical installations and structural elements of the building (walls, ceilings, cornices) and the ground. The authors of the paper will present the innovative design and technology of this specialized instrumentation. They will discuss issues arising during the implementation and use of the building.

  16. Experimental Measurement of Relative Permeability Functions for Fuel Cell GDL Materials

    KAUST Repository

    Hussaini, Irfan

    2009-01-01

    Gas diffusion layer in PEM fuel cells plays a pivotal role in water management. Modeling of liquid water transport through the GDL relies on knowledge of relative permeability functions in the in-plane and through-plane directions. In the present work, air and water relative permeabilities are experimentally determined as functions of saturation for typical GDL materials such as Toray-060, -090, -120 carbon paper and E-Tek carbon cloth materials in their plain, untreated forms. Saturation is measured using an ex-situ gravimetric method. Absolute and relative permeability functions in the two directions of interest are presented. Significant departure from the generally assumed cubic function of saturation is observed. ©The Electrochemical Society.

  17. Direct experimental measurement of single-mode and mode-hopping dynamics in frequency swept lasers.

    Science.gov (United States)

    Butler, T P; Goulding, D; Kelleher, B; O'Shaughnessy, B; Slepneva, S; Hegarty, S P; Huyet, G

    2017-10-30

    A time-resolved study is presented of the single-mode and mode-switching dynamics observed in swept source vertical cavity surfing emitting lasers and swept wavelength short external cavity lasers. A self-delayed interferometric technique is used to experimentally measure the phase and intensity of these frequency swept lasers, allowing direct examination of the modal dynamics. Visualisation of the instantaneous optical spectrum reveals mode-hop free single mode lasing in the case of the vertical cavity laser, with a tuning rate of 6.3 GHz/ns. More complex mode-switching behaviour occurs in the external cavity laser, with the mode-hopping dynamics found to be dominated by the deterministic movement of the spectral filter. Evidence of transient multi-mode operation and mode-pulling is also presented.

  18. A New Differential Pressure Flow Meter for Measurement of Human Breath Flow: Simulation and Experimental Investigation.

    Science.gov (United States)

    Bridgeman, Devon; Tsow, Francis; Xian, Xiaojun; Forzani, Erica

    2016-03-01

    The development and performance characterization of a new differential pressure-based flow meter for human breath measurements is presented in this article. The device, called a "Confined Pitot Tube," is comprised of a pipe with an elliptically shaped expansion cavity located in the pipe center, and an elliptical disk inside the expansion cavity. The elliptical disk, named Pitot Tube, is exchangeable, and has different diameters, which are smaller than the diameter of the elliptical cavity. The gap between the disk and the cavity allows the flow of human breath to pass through. The disk causes an obstruction in the flow inside the pipe, but the elliptical cavity provides an expansion for the flow to circulate around the disk, decreasing the overall flow resistance. We characterize the new sensor flow experimentally and theoretically, using Comsol Multiphysics® software with laminar and turbulent models. We also validate the sensor, using inhalation and exhalation tests and a reference method.

  19. Comparison of analytical calculations with experimental measurements for polarized light scattering by microorganisms

    Science.gov (United States)

    Hull, Patricia G.; Shaw, Felecia G.; Quinby-Hunt, Mary S.; Shapiro, Daniel B.; Hunt, Arlon J.; Leighton, Terrence

    1994-10-01

    The consequences of light scattering from both spherical and non-spherical particles on the propagation of light in the ocean were investigated. The scattering from an ensemble of non- spherical micro-organisms is calculated using the coupled-dipole approximation with an orientational average over Euler angles using Gauss-Legendre integration. Mie calculations provide rigorous solutions for spherical particles and are considerably less computer intensive than the coupled-dipole approximation. Furthermore, they have been shown to accurately predict the scattering for marine organisms that are nearly spherical. Scattering matrix elements calculated using the coupled-dipole approximation were compared with those obtained using Mie calculations in the limit as an ellipsoidal object approaches a sphere in order to assess the limits of applicability of the Mie theory to ellipsoidal particles. Experimental measurements of the scattering matrix elements for spherical particles (latex spheres) and ellipsoidal particles (Bacillus subtilis) were used to test the validity of our analytical approach.

  20. An experimental method of measuring the quasi-static and dynamic confined behaviour of PMMA

    Directory of Open Access Journals (Sweden)

    Siad L.

    2010-06-01

    Full Text Available A testing device is presented for the experimental study of the confined behaviour of PMMA in compression under quasi-static loading or at high strain-rates. The constitutive relation of the material ring (allowing to confine the PMMA being known, transverse gauges glued on its lateral surface allow for the measurement of the lateral confining pressure. The hydrostatic pressure and the Mises stress may be computed. Quasi-static and dynamic tests performed in a strain-rate range of 1e-3/s 1e3/s are processed with the method and compared to results of unconfined compression tests. It is found that the compressive behaviour of PMMA is weakly influenced by the level of pressure and much more sensitive to strain-rate: an elastic brittle behaviour is observed at high strain-rates in unconfined or confined conditions whereas elastoplastic behaviour is noted under quasi-static loading.

  1. Analysis of the laser powder bed fusion additive manufacturing process through experimental measurement and finite element modeling

    Science.gov (United States)

    Dunbar, Alexander Jay

    The objective in this work is to provide rigourous experimental measurements to aid in the development of laser powder bed fusion (LPBF) additive manufacturing (AM). A specialized enclosed instrumented measurement system is designed to provide in situ experimental measurements of temperature and distortion. Experiments include comparisons of process parameters, materials and LPBF machines. In situ measurements of distortion and temperature made throughout the build process highlight inter-layer distortion effects previously undocumented for laser powder bed fusion. Results from these experiments are also be implemented in the development and validation of finite element models of the powder bed build process. Experimental analysis is extended from small-scale to larger part-scale builds where experimental post-build measurements are used in analysis of distortion profiles. Experimental results provided from this study are utilized in the validation of a finite element model capable of simulating production scale parts. The validated finite element model is then implemented in the analysis of the part to provide information regarding the distortion evolution process. A combination of experimental measurements and simulation results are used to identify the mechanism that results in the measured distortion profile for this geometry. Optimization of support structure primarily focuses on the minimization of material use and scan time, but no information regarding failure criteria for support structure is available. Tensile test samples of LPBF built support structure are designed, built, and tested to provide measurements of mechanical properties of the support structure. Experimental tests show that LPBF built support structure has only 30-40% of the ultimate tensile strength of solid material built in the same machine. Experimental measurement of LPBF built support structure provides clear failure criteria to be utilized in the future design and implementation of

  2. Evaluation of statin therapy on endothelial function in hypercholesterolemic rabbits by automatic measurement of arterial wall movement using ultrasound images.

    Science.gov (United States)

    Rahmani-Cherati, Tavoos; Mokhtari-Dizaji, Manijhe; Vajhi, Alireza; Rostami, Abdorrazzagh

    2014-10-01

    The aim of this study was to evaluate arterial endothelial function, assessed as acetylcholine-mediated dilation (AMD), in a hypercholesterolemic atherosclerotic rabbit model to investigate the effects of atorvastatin in the atherosclerotic process, using a new computerized analysis model and ultrasound images. Twenty-seven rabbits were fed a high-cholesterol (2%) diet for 6 wk and then divided into three groups for an additional 9 wk: Group A received regular chow food, group B received a 2% cholesterol-rich diet plus atorvastatin drug, and group C received regular chow food plus atorvastatin. Ultrasound examinations of endothelial function of the rabbit abdominal aorta artery were performed immediately after the 6 weeks (0 wk) and then 3, 6 and 9 wk after that. For off-line analysis, a computerized analysis method for evaluating instantaneous changes in the wall of the rabbit abdominal aorta was used. As parameters of improvement resulting from treatment, endothelium-dependent acetylcholine-induced dilation and endothelium-independent nitroglycerin-induced dilation were evaluated in treated rabbits. Differences among groups were tested using analysis of variance. On histopathology, intima-media thickness decreased after treatment in all groups. There were no significant differences in arterial diameter and blood velocity changes among treated rabbits at 0, 3, 6 and 9 wk of treatment in all groups, except in end-diastolic velocity, radial strain percentage, pulse index and resistance index in group C. In group A, AMD did not significantly improve after 3, 6 and 9 wk, as compared with 0 wk. Atorvastatin treatment significantly increased AMD (18%) at 3 wk in group B, compared with week 0. AMD significantly increased after 3 (26%), 6 (124%) and 9 (182%) wk in group C, compared with 0 wk. It is concluded that the new automatic method enables accurate and repeated evaluation of endothelial function during the progression and regression of atherosclerosis. Also, the

  3. Measurement of scattered radiation in a volumetric 64-slice CT scanner using three experimental techniques

    Energy Technology Data Exchange (ETDEWEB)

    Akbarzadeh, A; Ay, M R; Sarkar, S [Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Ghadiri, H [Research Center for Science and Technology in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Zaidi, H [Division of Nuclear Medicine, Geneva University Hospital, CH-1211 Geneva (Switzerland)], E-mail: mohammadreza_ay@tums.ac.ir

    2010-04-21

    Compton scatter poses a significant threat to volumetric x-ray computed tomography, bringing cupping and streak artefacts thus impacting qualitative and quantitative imaging procedures. To perform appropriate scatter compensation, it is necessary to estimate the magnitude and spatial distribution of x-ray scatter. The aim of this study is to compare three experimental methods for measurement of the scattered radiation profile in a 64-slice CT scanner. The explored techniques involve the use of collimator shadow, a single blocker (a lead bar that suppresses the primary radiation) and an array blocker. The latter was recently proposed and validated by our group. The collimator shadow technique was used as reference for comparison since it established itself as the most accurate experimental procedure available today. The mean relative error of measurements in all tube voltages was 3.9 {+-} 5.5% (with a maximum value of 20%) for the single blocker method whereas it was 1.4 {+-} 1.1% (with a maximum value of 5%) for the proposed blocker array method. The calculated scatter-to-primary ratio (SPR) using the blocker array method for the tube voltages of 140 kVp and 80 kVp was 0.148 and 1.034, respectively. For a larger polypropylene phantom, the maximum SPR achieved was 0.803 and 6.458 at 140 kVp and 80 kVp, respectively. Although the three compared methods present a reasonable accuracy for calculation of the scattered profile in the region corresponding to the object, the collimator shadow method is by far the most accurate empirical technique. Nevertheless, the blocker array method is relatively straightforward for scatter estimation providing minor additional radiation exposure to the patient.

  4. Measurement precision and biological variation of cranial arteries using automated analysis of 3 T magnetic resonance angiography

    DEFF Research Database (Denmark)

    Amin, Faisal Mohammad; Lundholm, Elisabet; Hougaard, Anders

    2014-01-01

    -to-day, and side-to-side variations of the circumference of the middle meningeal (MMA) and middle cerebral (MCA) arteries. RESULTS: We found an excellent intra- and interobserver agreement for the MMA (ICC: 0.909-0.987) and for the MCA (ICC: 0.876-0.949). The coefficient of variance within observers was ≤1.......8% for MMA and ≤3.1% for MCA; between observers ≤3.4% (MMA) and ≤4.1% (MCA); between days ≤6.0% (MMA) and ≤8.0% (MCA); between sides ≤9.4% (MMA) and ≤6.5% (MCA). CONCLUSION: The present study demonstrates a low (... software. Furthermore, the study also suggests that the day-to-day and side-to-side variations of the MMA and MCA circumferences are less than 10%....

  5. Comparison of arterial input functions measured from ultra-fast dynamic contrast enhanced MRI and dynamic contrast enhanced computed tomography in prostate cancer patients

    Science.gov (United States)

    Wang, Shiyang; Lu, Zhengfeng; Fan, Xiaobing; Medved, Milica; Jiang, Xia; Sammet, Steffen; Yousuf, Ambereen; Pineda, Federico; Oto, Aytekin; Karczmar, Gregory S.

    2018-02-01

    The purpose of this study was to evaluate the accuracy of arterial input functions (AIFs) measured from dynamic contrast enhanced (DCE) MRI following a low dose of contrast media injection. The AIFs measured from DCE computed tomography (CT) were used as ‘gold standard’. A total of twenty patients received CT and MRI scans on the same day. Patients received 120 ml Iohexol in DCE-CT and a low dose of (0.015 mM kg‑1) of gadobenate dimeglumine in DCE-MRI. The AIFs were measured in the iliac artery and normalized to the CT and MRI contrast agent doses. To correct for different temporal resolution and sampling periods of CT and MRI, an empirical mathematical model (EMM) was used to fit the AIFs first. Then numerical AIFs (AIFCT and AIFMRI) were calculated based on fitting parameters. The AIFMRI was convolved with a ‘contrast agent injection’ function (AIFMRICON ) to correct for the difference between MRI and CT contrast agent injection times (~1.5 s versus 30 s). The results show that the EMMs accurately fitted AIFs measured from CT and MRI. There was no significant difference (p  >  0.05) between the maximum peak amplitude of AIFs from CT (22.1  ±  4.1 mM/dose) and MRI after convolution (22.3  ±  5.2 mM/dose). The shapes of the AIFCT and AIFMRICON were very similar. Our results demonstrated that AIFs can be accurately measured by MRI following low dose contrast agent injection.

  6. Effects of various factors on Doppler flow ultrasonic radial and coccygeal artery systolic blood pressure measurements in privately-owned, conscious dogs

    Directory of Open Access Journals (Sweden)

    Allison P. Mooney

    2017-03-01

    Full Text Available Objective The purpose of this study was to assess the effects of age, body condition score (BCS and muscle condition score (MCS on indirect radial and coccygeal Doppler systolic arterial blood pressure (SAP measurements in dogs. Methods Sixty-two privately-owned dogs were enrolled between June and July 2016. The BCS and MCS were determined by two investigators. Blood pressure was measured per published guidelines and using headphones, and the order of measurement site was randomized. Dogs were positioned in right lateral recumbency for radial measurements and sternal recumbency or standing for coccygeal measurements. Associations between SAP and other variables were assessed by correlation coefficients and analysis of covariance. Results Radial and coccygeal SAP measurements were moderately correlated (r = 0.45, P < 0.01. Radial SAP measurements were higher than coccygeal SAP measurements (mean difference 9 mmHg, P < 0.01, but discordance occurred in both directions. No difference was observed between the first measurement taken, the average of measurements 2–6, or the average of all 6 measurements for either the radial (128, 129, and 129 mmHg; P = 0.36 or coccygeal (121, 122, and 122 mmHg; P = 0.82 site. Associations were not found between SAP measurements for either site and age, weight, BCS, MCS, anxiety score, or cuff size. Heart rate decreased significantly from the start of acclimation to the end of the first data collection series regardless of site (P < 0.01. Conclusions and Clinical Relevance Initial measurement site can be based on patient and operator preference given lack of associations with patient variables, but the same site should be used for serial SAP measurements given discordant results between sites.

  7. Coronary Arteries

    Science.gov (United States)

    ... animations for grades K-6. The Coronary Arteries Coronary Circulation The heart muscle, like every other organ or ... the heart by its own vascular system, called coronary circulation. The aorta (the main blood supplier to the ...

  8. Dissolution of peripheral arterial thrombi by ultrasound.

    Science.gov (United States)

    Ariani, M; Fishbein, M C; Chae, J S; Sadeghi, H; Michael, A D; Dubin, S B; Siegel, R J

    1991-10-01

    We have previously shown that continuous-wave ultrasound can rapidly dissolve human thrombi in vitro, with 99% of all residual particles measuring less than 10 microns in diameter. To assess the effects of pulsed-wave ultrasound energy on whole blood clots, 1) in vitro studies were preformed to assess precisely the rates of clot disruption and to quantify particulate size, and 2) in vivo studies were performed to assess the efficacy and safety of catheter-delivered ultrasound for intra-arterial thrombus dissolution. In vitro, we studied 50 samples of human whole blood clots and using an 89-cm-long wire probe, applied pulse-wave energies from 8 to 23 W. The corresponding peak-to-peak tip displacement range was 63.5 - 102 microns. We studied arterial thrombosis in vivo in 21 canine superficial femoral arteries. To produce an acute thrombosis, 200 units of thrombin followed by 2 ml of 72-hour-old autologous clot were injected into a 5-7-cm segment of femoral artery and left to coagulate for 2 hours. Ultrasound energy was intermittently applied at a frequency of 20 kHz with a prototype ultrasound wire ensheathed in a catheter and directed to clots by fluoroscopy. In nine cases, angioscopic guidance was used to put the probe into direct contact with the intra-arterial thromboses. In vitro clot dissolution times were inversely related to the ultrasound power output (r = 0.95). All in vivo canine thromboses were disrupted in 4 minutes or less. All successful recanalizations were confirmed by angiography and in nine cases by angioscopy as well. Angioscopy demonstrated that probe activation caused rapid clot disruption. Histological studies of the vessels showed no evidence of thermal or cavitation injury, occlusive distal embolization, or perforation. Our findings in this experimental canine model suggest that ultrasound clot dissolution has the potential to be an effective and safe alternative to current treatment modalities for peripheral arterial thrombosis.

  9. Experimental measurements of diffraction for periodic patterns by 193-nm polarized radiation compared to rigorous EMF simulations

    Science.gov (United States)

    Bennett, Marylyn H.; Grenville, Andrew; Hector, Scott D.; Palmer, Shane R.; Leunissen, Leonardus H. A.; Philipsen, Vicky; Bloomstein, Theodore M.; Hardy, Dennis E.; Rothschild, Mordechai; Hilfiker, James N.

    2005-05-01

    Polarization dependent diffraction efficiencies in transmission through gratings on specially designed masks with pitch comparable to the wavelength were measured using an angle-resolved scatterometry apparatus with a 193 nm excimer source. Four masks - two binary, one alternating and one attenuated phase shift mask - were included in the experimental measurements. The validity of models used in present commercially available simulation packages and additional polarization effects were evaluated against the experimental scattering efficiencies.

  10. Calibration of aero-structural reduced order models using full-field experimental measurements

    Science.gov (United States)

    Perez, R.; Bartram, G.; Beberniss, T.; Wiebe, R.; Spottswood, S. M.

    2017-03-01

    The structural response of hypersonic aircraft panels is a multi-disciplinary problem, where the nonlinear structural dynamics, aerodynamics, and heat transfer models are coupled. A clear understanding of the impact of high-speed flow effects on the structural response, and the potential influence of the structure on the local environment, is needed in order to prevent the design of overly-conservative structures, a common problem in past hypersonic programs. The current work investigates these challenges from a structures perspective. To this end, the first part of this investigation looks at the modeling of the response of a rectangular panel to an external heating source (thermo-structural coupling) where the temperature effect on the structure is obtained from forward looking infrared (FLIR) measurements and the displacement via 3D-digital image correlation (DIC). The second part of the study uses data from a previous series of wind-tunnel experiments, performed to investigate the response of a compliant panel to the effects of high-speed flow, to train a pressure surrogate model. In this case, the panel aero-loading is obtained from fast-response pressure sensitive paint (PSP) measurements, both directly and from the pressure surrogate model. The result of this investigation is the use of full-field experimental measurements to update the structural model and train a computational efficient model of the loading environment. The use of reduced order models, informed by these full-field physical measurements, is a significant step toward the development of accurate simulation models of complex structures that are computationally tractable.

  11. MRI-based flow measurements in the main pulmonary artery to detect pulmonary arterial hypertension in patients with cystic fibrosis; MRT-basierte Flussmessungen im Truncus pulmonalis zur Detektion einer pulmonal-arteriellen Hypertonie in Patienten mit zystischer Fibrose

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, T.; Anjorin, A.; Abolmaali, N. [TU Dresden (Germany). OncoRay, Biologisches und Molekulares Imaging; Posselt, H. [Frankfurt Univ. (Germany). Klinik fuer Paediatrie I, Muskoviszidoseambulanz; Smaczny, C. [Frankfurt Univ. (Germany). Medizinische Klinik I, Pneumologie und Allergologie; Vogl, T.J. [Frankfurt Univ. (Germany). Inst. fuer Diagnostische und Interventionelle Radiologie

    2009-02-15

    Development of pulmonary arterial hypertension (PH) is a common problem in the course of patients suffering from cystic fibrosis (CF). This study was performed to evaluate MRI based flow measurements (MR{sub venc}; Velocity ENCoding) to detect signs of an evolving PH in patients suffering from CF. 48 patients (median age: 16 years, range: 10 - 40 years, 25 female) suffering from CF of different severity (mean FEV1: 74 % {+-} 23, mean Shwachman-score: 63 {+-} 10) were examined using MRI based flow measurements of the main pulmonary artery (MPA). Phase-contrast flash sequences (TR: 9.6 ms, TE: 2.5 ms, bandwidth: 1395 Hertz/Pixel) were utilized. Results were compared to an age- and sex-matched group of 48 healthy subjects. Analyzed flow data where: heart frequency (HF), cardiac output (HZV), acceleration time (AT), proportional acceleration time related to heart rate (ATr), mean systolic blood velocity (MFG), peak velocity (Peak), maximum flow (Fluss{sub max}), mean flow (Fluss{sub mitt}) and distensibility (Dist). The comparison of means revealed significant differences only for MFG, Fluss{sub max} and Dist, but overlap was marked. However, using a scatter-plot of AT versus MFG, it was possible to identify five CF-patients demonstrating definite signs of PH: AT = 81 ms {+-} 14, MFG = 46 {+-} 11 cm/s, Dist = 41 % {+-} 7. These CF-patients where the most severely affected in the investigated group, two of them were listed for complete heart and lung transplantation. The comparison of this subgroup and the remaining CF-patients revealed a highly significant difference for the AT (p = 0.000001) without overlap. Screening of CF-patients for the development of PH using MR{sub venc} of the MPA is not possible. In later stages of disease, the quantification of AT, MFG and Dist in the MPA may be useful for the detection, follow-up and control of therapy of PH. MR{sub venc} of the MPA completes the MRI-based follow-up of lung parenchyma damage in patients suffering from CF

  12. Validación del índice tobillo brazo oscilométrico comparado con eco-Doppler arterial de miembros inferiores para enfermedad arterial Validation of oscillometric measurement of ankle-brachial index compared with arterial lower limb echo-doppler for arterial disease

    OpenAIRE

    Astrid N Páez E; Myriam Oróstegui A; Héctor J Hernández G; Laura I Valencia A; Carlos I Reyes S; Luis F Tapias V; Luis C. Orozco V

    2010-01-01

    INTRODUCCIÓN: estudios previos reportan la validación y correspondencia, o ambas, del índice tobillo brazo oscilométrico frente al índice tobillo brazo con Doppler, pero este último no corresponde al patrón de oro. OBJETIVO: determinar la validez de criterio del índice tobillo brazo oscilométrico comparado con la ecografía dúplex arterial de miembros inferiores para detectar enfermedad arterial periférica. METODOLOGÍA: estudio de evaluación de tecnologías diagnósticas realizado por muestreo t...

  13. Experimental measurement of 12C+16O fusion at stellar energies

    Science.gov (United States)

    Fang, X.; Tan, W. P.; Beard, M.; deBoer, R. J.; Gilardy, G.; Jung, H.; Liu, Q.; Lyons, S.; Robertson, D.; Setoodehnia, K.; Seymour, C.; Stech, E.; Vande Kolk, B.; Wiescher, M.; deSouza, R. T.; Hudan, S.; Singh, V.; Tang, X. D.; Uberseder, E.

    2017-10-01

    The total cross section of the 12C+16O fusion reaction has been measured at low energies to investigate the role of this reaction during late stellar evolution burning phases. A high-intensity oxygen beam, produced by the 5 MV pelletron accelerator at the University of Notre Dame, impinged on a thick, ultrapure graphite target. Protons and γ rays were simultaneously measured in the center-of-mass energy range from 3.64 to 5.01 MeV for singles and from 3.73 to 4.84 MeV for coincidence events, using silicon and Ge detectors. Statistical model calculations were employed to interpret the experimental results. The emergence of a new resonance-like broad structure and a decreasing trend in the S -factor data towards lower energies (opposite to previous data) are found for the 12C+16O fusion reaction. Based on these results the uncertainty range of the reaction rate within the temperature range of late stellar burning environments is discussed.

  14. Experimentally measured susceptibility to peer influence and adolescent sexual behavior trajectories: A preliminary study.

    Science.gov (United States)

    Choukas-Bradley, Sophia; Giletta, Matteo; Widman, Laura; Cohen, Geoffrey L; Prinstein, Mitchell J

    2014-09-01

    A performance-based measure of peer influence susceptibility was examined as a moderator of the longitudinal association between peer norms and trajectories of adolescents' number of sexual intercourse partners. Seventy-one 9th grade adolescents (52% female) participated in an experimental "chat room" paradigm involving "e-confederates" who endorsed sexual risk behaviors. Changes in participants' responses to risk scenarios before versus during the "chat room" were used as a performance-based measure of peer influence susceptibility. Participants reported their perceptions of popular peers' number of sexual intercourse partners at baseline and self-reported their number of sexual intercourse partners at baseline and 6, 12, and 18 months later. Susceptibility was examined as a moderator of the longitudinal association between perceptions of popular peers' number of sexual intercourse partners and trajectories of adolescents' own numbers of partners. High perceptions of the number of popular peers' sexual intercourse partners combined with high peer influence susceptibility predicted steeper longitudinal trajectories of adolescents' number of partners. Results provide novel preliminary evidence regarding the importance of peer influence susceptibility in adolescents' development of sexual behaviors.

  15. Experimental measurement of preferences in health and healthcare using best-worst scaling: an overview.

    Science.gov (United States)

    Mühlbacher, Axel C; Kaczynski, Anika; Zweifel, Peter; Johnson, F Reed

    2016-12-01

    Best-worst scaling (BWS), also known as maximum-difference scaling, is a multiattribute approach to measuring preferences. BWS aims at the analysis of preferences regarding a set of attributes, their levels or alternatives. It is a stated-preference method based on the assumption that respondents are capable of making judgments regarding the best and the worst (or the most and least important, respectively) out of three or more elements of a choice-set. As is true of discrete choice experiments (DCE) generally, BWS avoids the known weaknesses of rating and ranking scales while holding the promise of generating additional information by making respondents choose twice, namely the best as well as the worst criteria. A systematic literature review found 53 BWS applications in health and healthcare. This article expounds possibilities of application, the underlying theoretical concepts and the implementation of BWS in its three variants: 'object case', 'profile case', 'multiprofile case'. This paper contains a survey of BWS methods and revolves around study design, experimental design, and data analysis. Moreover the article discusses the strengths and weaknesses of the three types of BWS distinguished and offered an outlook. A companion paper focuses on special issues of theory and statistical inference confronting BWS in preference measurement.

  16. Accurate Profile Measurement of the low Intensity Secondary Beams in the CERN Experimental Areas

    CERN Document Server

    AUTHOR|(CDS)2084531; Tranquille, Gerard

    2018-02-23

    The CERN accelerators deliver a wide spectrum of secondary beams to the Experimental Areas. These beams are composed of hadrons, leptons, and heavy ions that can vary greatly in momentum (1 GeV/c to 400 GeV/c) and intensity (10^2 to 10^8 particles per second). The profile, position, and intensity of these beams are measured utilising particle detectors. However, the current systems show several problems that limit the quality of this kind of monitoring. The aim of this doctoral thesis is to investigate the best detector technology that could replace the existing monitors and build a first prototype of it. A review of the existing detection techniques has led to the choice of Scintillating Fibres (SciFi) read-out with Silicon Photomultipliers (SiPM). This detection technology has the potential to perform better in terms of material budget, range of intensities measured, and active area size. In addition, it has particle counting capabilities, which could extend its application to momentum spectrometry or Time...

  17. Experimentally-Measured Susceptibility to Peer Influence and Adolescent Sexual Behavior Trajectories: A Preliminary Study

    Science.gov (United States)

    Choukas-Bradley, Sophia; Giletta, Matteo; Widman, Laura; Cohen, Geoffrey L.; Prinstein, Mitchell J.

    2014-01-01

    A performance-based measure of peer influence susceptibility was examined as a moderator of the longitudinal association between peer norms and trajectories of adolescents' number of sexual intercourse partners. Seventy-one 9th grade adolescents (52% female) participated in an experimental “chat room” paradigm involving “e-confederates” who endorsed sexual risk behaviors. Changes in participants' responses to risk scenarios before versus during the “chat room” were used as a performance-based measure of peer influence susceptibility. Participants reported their perceptions of popular peers' number of sexual intercourse partner sat baseline, and self-reported their number of sexual intercourse partners at baseline and 6, 12, and 18 months later. Susceptibility was examined as a moderator of the longitudinal association between perceptions of popular peers' number of sexual intercourse partners and trajectories of adolescents' own numbers of partners. High perceptions of the number of popular peers' sexual intercourse partners combined with high peer influence susceptibility predicted steeper longitudinal trajectories of adolescents' number of partners. Results provide novel preliminary evidence regarding the importance of peer influence susceptibility in adolescents' development of sexual behaviors. PMID:24999763

  18. Experimental Measurements for Numerical Simulation of Macrosegregation in a 36-Ton Steel Ingot

    Science.gov (United States)

    Duan, Zhenhu; Tu, Wutao; Shen, Bingzhen; Shen, Houfa; Liu, Baicheng

    2016-07-01

    In order to cognize the macrosegregation formation with solidification conditions, a 36-ton steel ingot has been experimentally investigated. Temperature variations of fourteen specified positions, for both the mold and ingot, were monitored to acquire the thermal conditions during solidification. Calibrated heat transfer coefficients between the ingot and mold were determined based on the temperature measurements and the empirical formula. Besides, concentration distributions of both carbon and sulfur in the ingot longitudinal section were mapped by 1800 drilled samples. Macrosegregation patterns were obtained, and notable negative segregations along the side walls of hot-top as well as typical segregation characteristics were presented in the maps. Segregation extent of sulfur was greater than that of carbon, and the segregated sulfur was relevant to the segregated carbon in a certain extent on statistical analysis with a standard correlation coefficient r = 0.68872. Finally, a two-phase multiscale multicomponent solidification model was preliminarily utilized to predict the species segregation. General good agreements are exhibited for the comparisons between the prediction and measurement of concentration profiles of carbon and sulfur in ingot.

  19. An experimental setup for visualizations and measurements on free hypersonic jets

    Directory of Open Access Journals (Sweden)

    Tordella Daniela

    2012-04-01

    Full Text Available The free hypersonic jets can be found in several technological applications and even in astrophysical observations. This article is mainly devoted to explain an experiment about visualizations and measurements on free hypersonic jets extending on length scales in the order of hundreds of initial diameters and traveling in a medium not necessarily made of the same gas of the jets. The experiments are performed by means of special facilities where the jet Mach numbers and the jetto-ambient density ratios can be set independently of each other, what permits the investigation of a wide parameters range in the relevant physics. The Mach number of the jets ranges from 5 to 20 and the jet-to ambient density ratio, which plays an important role in the jets morphology, can be set from 0.1 up to values exceeding 100. The present setup produces the jets by means of a fast piston system (for high Mach numbers or injection valves (for low Mach numbers, both coupled with de Laval nozzles. The visualizations and measurements are based on the electron beam technique: the jets are weakly ionized, then a fast CMOS camera captures images that are analyzed by image processing techniques. A sample of the results obtained by this experimental system is included at the end of this work.

  20. Wall-based measurement features provides an improved IVUS coronary artery risk assessment when fused with plaque texture-based features during machine learning paradigm.

    Science.gov (United States)

    Banchhor, Sumit K; Londhe, Narendra D; Araki, Tadashi; Saba, Luca; Radeva, Petia; Laird, John R; Suri, Jasjit S

    2017-12-01

    Planning of percutaneous interventional procedures involves a pre-screening and risk stratification of the coronary artery disease. Current screening tools use stand-alone plaque texture-based features and therefore lack the ability to stratify the risk. This IRB approved study presents a novel strategy for coronary artery disease risk stratification using an amalgamation of IVUS plaque texture-based and wall-based measurement features. Due to common genetic plaque makeup, carotid plaque burden was chosen as a gold standard for risk labels during training-phase of machine learning (ML) paradigm. Cross-validation protocol was adopted to compute the accuracy of the ML framework. A set of 59 plaque texture-based features was padded with six wall-based measurement features to show the improvement in stratification accuracy. The ML system was executed using principle component analysis-based framework for dimensionality reduction and uses support vector machine classifier for training and testing-phases. The ML system produced a stratification accuracy of 91.28%, demonstrating an improvement of 5.69% when wall-based measurement features were combined with plaque texture-based features. The fused system showed an improvement in mean sensitivity, specificity, positive predictive value, and area under the curve by: 6.39%, 4.59%, 3.31% and 5.48%, respectively when compared to the stand-alone system. While meeting the stability criteria of 5%, the ML system also showed a high average feature retaining power and mean reliability of 89.32% and 98.24%, respectively. The ML system showed an improvement in risk stratification accuracy when the wall-based measurement features were fused with the plaque texture-based features. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Multiple Giant Coronary Artery Aneurysms

    Science.gov (United States)

    Usuku, Hiroki; Kojima, Sunao; Kuyama, Naoto; Hanatani, Shinsuke; Araki, Satoshi; Tsujita, Kenichi; Tsunoda, Ryusuke; Fukui, Toshihiro; Hokimoto, Seiji

    2017-01-01

    A 74-year-old man was admitted to our hospital with chest pain and dyspnea associated with ST elevation in leads II, III and aVF. An echocardiogram showed an enlarged mass lesion measuring nearly 80 mm. Coronary angiography showed two giant coronary artery aneurysms (CAAs) in the right coronary artery (RCA). CAAs were also seen in the left main trunk and left anterior descending artery. Computed tomography showed the CAA in the RCA was ruptured into the right atrium. We therefore diagnosed this patient with multiple CAAs, myocardial infarction and coronary artery rupture. He underwent successful surgical excision and coronary bypass surgery. PMID:28768966

  2. Measuring reinforcement learning and motivation constructs in experimental animals: relevance to the negative symptoms of schizophrenia.

    Science.gov (United States)

    Markou, Athina; Salamone, John D; Bussey, Timothy J; Mar, Adam C; Brunner, Daniela; Gilmour, Gary; Balsam, Peter

    2013-11-01

    The present review article summarizes and expands upon the discussions that were initiated during a meeting of the Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS; http://cntrics.ucdavis.edu) meeting. A major goal of the CNTRICS meeting was to identify experimental procedures and measures that can be used in laboratory animals to assess psychological constructs that are related to the psychopathology of schizophrenia. The issues discussed in this review reflect the deliberations of the Motivation Working Group of the CNTRICS meeting, which included most of the authors of this article as well as additional participants. After receiving task nominations from the general research community, this working group was asked to identify experimental procedures in laboratory animals that can assess aspects of reinforcement learning and motivation that may be relevant for research on the negative symptoms of schizophrenia, as well as other disorders characterized by deficits in reinforcement learning and motivation. The tasks described here that assess reinforcement learning are the Autoshaping Task, Probabilistic Reward Learning Tasks, and the Response Bias Probabilistic Reward Task. The tasks described here that assess motivation are Outcome Devaluation and Contingency Degradation Tasks and Effort-Based Tasks. In addition to describing such methods and procedures, the present article provides a working vocabulary for research and theory in this field, as well as an industry perspective about how such tasks may be used in drug discovery. It is hoped that this review can aid investigators who are conducting research in this complex area, promote translational studies by highlighting shared research goals and fostering a common vocabulary across basic and clinical fields, and facilitate the development of medications for the treatment of symptoms mediated by reinforcement learning and motivational deficits. Copyright © 2013 Elsevier

  3. Measuring reinforcement learning and motivation constructs in experimental animals: relevance to the negative symptoms of schizophrenia

    Science.gov (United States)

    Markou, Athina; Salamone, John D.; Bussey, Timothy; Mar, Adam; Brunner, Daniela; Gilmour, Gary; Balsam, Peter

    2013-01-01

    The present review article summarizes and expands upon the discussions that were initiated during a meeting of the Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS; http://cntrics.ucdavis.edu). A major goal of the CNTRICS meeting was to identify experimental procedures and measures that can be used in laboratory animals to assess psychological constructs that are related to the psychopathology of schizophrenia. The issues discussed in this review reflect the deliberations of the Motivation Working Group of the CNTRICS meeting, which included most of the authors of this article as well as additional participants. After receiving task nominations from the general research community, this working group was asked to identify experimental procedures in laboratory animals that can assess aspects of reinforcement learning and motivation that may be relevant for research on the negative symptoms of schizophrenia, as well as other disorders characterized by deficits in reinforcement learning and motivation. The tasks described here that assess reinforcement learning are the Autoshaping Task, Probabilistic Reward Learning Tasks, and the Response Bias Probabilistic Reward Task. The tasks described here that assess motivation are Outcome Devaluation and Contingency Degradation Tasks and Effort-Based Tasks. In addition to describing such methods and procedures, the present article provides a working vocabulary for research and theory in this field, as well as an industry perspective about how such tasks may be used in drug discovery. It is hoped that this review can aid investigators who are conducting research in this complex area, promote translational studies by highlighting shared research goals and fostering a common vocabulary across basic and clinical fields, and facilitate the development of medications for the treatment of symptoms mediated by reinforcement learning and motivational deficits. PMID:23994273

  4. Development of Aerosol Measurement, Sampling and Generation Experimental Facilities under High Temperature and High Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Chan; Jung, Woo Young; Lee, Hyun Chul; Lee, Doo Yong [FNC TECH., Yongin (Korea, Republic of)

    2016-05-15

    The pressure is key factor determining Knudsen number and it affects aerosol dynamics. Hence, it is important to design experimental facilities to simulate the aerosols transport phenomena and removal mechanisms in the high temperature and high pressure (HT/HP). In case of Nuclear Power Plant, during the Light Water Reactor (LWR) severe accident, core degradation results in the release of both vapors and aerosol particles which differ in composition depending on their source terms. Vapor and aerosols generated under severe accident enter the containment atmosphere and are distributed in the containment by atmospheric flow. Temperature and pressure in the containment increase until containment spray system, fan cooler system or FCVS initiates to extract heat and avoid pressurization. The main purpose of the experimental facility is to develop not only multi-purpose test loops applying for aerosol industry but also to evaluation performance of engineered safety system including containment filtered venting system. The main experiment will be carried out in this loop and provide representative behavior of the aerosols under HT/HP conditions. The aim of the research is to be able to 1) develop the aerosol generation, mixing, sampling and measurement system and conduct tests based on various aerosol concentration, thermal-hydraulic conditions including high temperature and pressure and type of carrier gases (air, nitrogen and steam), applicable to the thermal power plant, environmental industry, automobile exhaust gas, chemical plant, HVAC system including nuclear power plant, and 2) investigate aerosol behaviors and removal mechanisms under these conditions. The tests with the main carrier gas of air will be performed on PHASEⅠ, steam will be conducted on PHASEⅡ.

  5. Accurate measurement of absolute experimental inelastic mean free paths and EELS differential cross-sections

    Energy Technology Data Exchange (ETDEWEB)

    Craven, Alan J.; Bobynko, Joanna; Sala, Bianca; MacLaren, Ian, E-mail: ian.maclaren@glasgow.ac.uk

    2016-11-15

    Methods are described for measuring accurate absolute experimental inelastic mean free paths and differential cross-sections using DualEELS. The methods remove the effects of surface layers and give the results for the bulk materials. The materials used are VC{sub 0.83}, TiC{sub 0.98}, VN{sub 0.97} and TiN{sub 0.88} but the method should be applicable to a wide range of materials. The data was taken at 200 keV using a probe half angle of 29 mrad and a collection angle of 36 mrad. The background can be subtracted from under the ionisation edges, which can then be separated from each other. This is achieved by scaling Hartree-Slater calculated cross-sections to the edges in the atomic regions well above the threshold. The average scaling factors required are 1.00 for the non-metal K-edges and 1.01 for the metal L-edges (with uncertainties of a few percent). If preliminary measurements of the chromatic effects in the post-specimen lenses are correct, both drop to 0.99. The inelastic mean free path for TiC{sub 0.98} was measured as 103.6±0.5 nm compared to the prediction of 126.9 nm based on the widely used Iakoubovskii parameterisation. - Highlights: • We show how to extract absolute cross sections for EELS edges using DualEELS. • The method removes the effects of any surface layers on standards. • We use a needle specimen to determining the mean free path for inelastic scattering. • Constrained background fitting is essential to correct background subtraction. • Absolute cross sections are determined for TiC, TiN, VC and VN.

  6. Experimental Test of the “Special State” Theory of Quantum Measurement

    Directory of Open Access Journals (Sweden)

    Lawrence S. Schulman

    2012-04-01

    Full Text Available An experimental test of the “special state” theory of quantum measurement is proposed. It should be feasible with present-day laboratory equipment and involves a slightly elaborated Stern–Gerlach setup. The “special state” theory is conservative with respect to quantum mechanics, but radical with respect to statistical mechanics, in particular regarding the arrow of time. In this article background material is given on both quantum measurement and statistical mechanics aspects. For example, it is shown that future boundary conditions would not contradict experience, indicating that the fundamental equal-a-priori-probability assumption at the foundations of statistical mechanics is far too strong (since future conditioning reduces the class of allowed states. The test is based on a feature of this theory that was found necessary in order to recover standard (Born probabilities in quantum measurements. Specifically, certain systems should have “noise” whose amplitude follows the long-tailed Cauchy distribution. This distribution is marked by the occasional occurrence of extremely large signals as well as a non-self-averaging property. The proposed test is a variant of the Stern–Gerlach experiment in which protocols are devised, some of which will require the presence of this noise, some of which will not. The likely observational schemes would involve the distinction between detection and non-detection of that “noise”. The signal to be detected (or not would be either single photons or electric fields (and related excitations in the neighborhood of the ends of the magnets.

  7. Experimental validation of a method for removing the capacitive leakage artifact from electrical bioimpedance spectroscopy measurements

    Science.gov (United States)

    Buendia, R.; Seoane, F.; Gil-Pita, R.

    2010-11-01

    Often when performing electrical bioimpedance (EBI) spectroscopy measurements, the obtained EBI data present a hook-like deviation, which is most noticeable at high frequencies in the impedance plane. The deviation is due to a capacitive leakage effect caused by the presence of stray capacitances. In addition to the data deviation being remarkably noticeable at high frequencies in the phase and the reactance spectra, the measured EBI is also altered in the resistance and the modulus. If this EBI data deviation is not properly removed, it interferes with subsequent data analysis processes, especially with Cole model-based analyses. In other words, to perform any accurate analysis of the EBI spectroscopy data, the hook deviation must be properly removed. Td compensation is a method used to compensate the hook deviation present in EBI data; it consists of multiplying the obtained spectrum, Zmeas(ω), by a complex exponential in the form of exp(-jωTd). Although the method is well known and accepted, Td compensation cannot entirely correct the hook-like deviation; moreover, it lacks solid scientific grounds. In this work, the Td compensation method is revisited, and it is shown that it should not be used to correct the effect of a capacitive leakage; furthermore, a more developed approach for correcting the hook deviation caused by the capacitive leakage is proposed. The method includes a novel correcting expression and a process for selecting the proper values of expressions that are complex and frequency dependent. The correctness of the novel method is validated with the experimental data obtained from measurements from three different EBI applications. The obtained results confirm the sufficiency and feasibility of the correcting method.

  8. Differences of cardiac output measurements by open-circuit acetylene uptake in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: a cohort study.

    Science.gov (United States)

    Schwaiblmair, Martin; Faul, Christian; von Scheidt, Wolfgang; Berghaus, Thomas M

    2012-03-12

    As differences in gas exchange between pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) have been demonstrated, we asked if cardiac output measurements determined by acetylene (C2H2) uptake significantly differed in these diseases when compared to the thermodilution technique. Single-breath open-circuit C2H2 uptake, thermodilution, and cardiopulmonary exercise testing were performed in 72 PAH and 32 CTEPH patients. In PAH patients the results for cardiac output obtained by the two methods showed an acceptable agreement with a mean difference of -0.16 L/min (95% CI -2.64 to 2.32 L/min). In contrast, the agreement was poorer in the CTEPH group with the difference being -0.56 L/min (95% CI -4.96 to 3.84 L/min). Functional dead space ventilation (44.5 ± 1.6 vs. 32.2 ± 1.4%, p < 0.001) and the mean arterial to end-tidal CO2 gradient (9.9 ± 0.8 vs. 4.1 ± 0.5 mmHg, p < 0.001) were significantly elevated among CTEPH patients. Cardiac output evaluation by the C2H2 technique should be interpreted with caution in CTEPH, as ventilation to perfusion mismatching might be more relevant than in PAH.

  9. An innovative experimental setup for Large Scale Particle Image Velocimetry measurements in riverine environments

    Science.gov (United States)

    Tauro, Flavia; Olivieri, Giorgio; Porfiri, Maurizio; Grimaldi, Salvatore

    2014-05-01

    Large Scale Particle Image Velocimetry (LSPIV) is a powerful methodology to nonintrusively monitor surface flows. Its use has been beneficial to the development of rating curves in riverine environments and to map geomorphic features in natural waterways. Typical LSPIV experimental setups rely on the use of mast-mounted cameras for the acquisition of natural stream reaches. Such cameras are installed on stream banks and are angled with respect to the water surface to capture large scale fields of view. Despite its promise and the simplicity of the setup, the practical implementation of LSPIV is affected by several challenges, including the acquisition of ground reference points for image calibration and time-consuming and highly user-assisted procedures to orthorectify images. In this work, we perform LSPIV studies on stream sections in the Aniene and Tiber basins, Italy. To alleviate the limitations of traditional LSPIV implementations, we propose an improved video acquisition setup comprising a telescopic, an inexpensive GoPro Hero 3 video camera, and a system of two lasers. The setup allows for maintaining the camera axis perpendicular to the water surface, thus mitigating uncertainties related to image orthorectification. Further, the mast encases a laser system for remote image calibration, thus allowing for nonintrusively calibrating videos without acquiring ground reference points. We conduct measurements on two different water bodies to outline the performance of the methodology in case of varying flow regimes, illumination conditions, and distribution of surface tracers. Specifically, the Aniene river is characterized by high surface flow velocity, the presence of abundant, homogeneously distributed ripples and water reflections, and a meagre number of buoyant tracers. On the other hand, the Tiber river presents lower surface flows, isolated reflections, and several floating objects. Videos are processed through image-based analyses to correct for lens

  10. Acoustic propagation in the Hudson River Estuary: Analysis of experimental measurements and numerical modeling results

    Science.gov (United States)

    Radhakrishnan, Sreeram

    Underwater intrusion detection is an ongoing security concern in port and harbor areas. Of particular interest is to detect SCUBA divers, unmanned underwater vehicles and small boats from their acoustic signature. A thorough understanding of the effects of the shallow water propagating medium on acoustic signals can help develop new technologies and improve the performance of existing acoustic based surveillance systems. The Hudson River Estuary provides us with such a shallow water medium to conduct research and improve our knowledge of shallow water acoustics. Acoustic propagation in the Hudson River Estuary is highly affected by the temporal and spatial variability of salinity and temperature due to tides, freshwater inflows, winds etc. The primary goal of this research is to help develop methodologies to predict the formation of an acoustic field in the realistic environment of the lower Hudson River Estuary. Shallow water high-frequency acoustic propagation experiments were conducted in the Hudson River near Hoboken, New Jersey. Channel Impulse Response (CIR) measurements were carried out in the frequency band from 10 to 100 kHz for distances up to 200 meters in a water depth of 8-10 meters which formed the basis for experimental Transmission Loss (TL). CIR data was also utilized to demonstrate multi-path propagation in shallow water. Acoustic propagation models based on Ray Theory and Parabolic Equation methods were implemented in the frequency band from 10 to 100 kHz and TL was estimated. The sound velocity profiles required as input by acoustic propagation models were calculated from in-situ measurements of temperature, salinity and depth. Surface reflection loss was obtained from CIR data and incorporated into the acoustic propagation models. Experimentally obtained TL was used to validate the acoustic model predictions. An outcome of this research is an operational acoustic transmission loss (TL) forecast system based on the existing, Stevens New York

  11. Normal ranges and test-retest reproducibility of flow and velocity parameters in intracranial arteries measured with phase-contrast magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Correia de Verdier, Maria; Wikstroem, Johan [Uppsala University Hospital, Department of Radiology, Uppsala University, Uppsala (Sweden)

    2016-05-15

    The purpose of the present study was to investigate normal ranges and test-retest reproducibility of phase-contrast MRI (PC-MRI)-measured flow and velocity parameters in intracranial arteries. Highest flow (HF), lowest flow (LF), peak systolic velocity (PSV), and end diastolic velocity (EDV) were measured at two dates in the anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries of 30 healthy volunteers using two-dimensional PC-MRI at 3 T. Least detectable difference (LDD) was calculated. In the left ACA, HF was (mean (range, LDD)) 126 ml/min (36-312, 59 %), LF 61 ml/min (0-156, 101 %), PSV 64 cm/s (32-141, 67 %), and EDV 35 cm/s (18-55, 42 %); in the right ACA, HF was 154 ml/min (42-246, 49 %), LF 77 ml/min (0-156, 131 %), PSV 75 cm/s (26-161, 82 %), and EDV 39 cm/s (7-59, 67 %). In the left MCA, HF was 235 ml/min (126-372, 35 %), LF 116 ml/min (42-186, 48 %), PSV 90 cm/s (55-183, 39 %), and EDV 46 cm/s (20-66, 28 %); in the right MCA, HF was 238 ml/min (162-342, 44 %), LF 120 ml/min (72-216, 48 %), PSV 88 cm/s (55-141, 35 %), and EDV 45 cm/s (26-67, 23 %). In the left PCA, HF was 108 ml/min (42-168, 54 %), LF 53 ml/min (18-108, 64 %), PSV 50 cm/s (24-77, 63 %), and EDV 28 cm/s (14-40, 45 %); in the right PCA, HF was 98 ml/min (30-162, 49 %), LF 49 ml/min (12-84, 55 %), PSV 47 cm/s (27-88, 59 %), and EDV 27 cm/s (16-41, 45 %). PC-MRI-measured flow and velocity parameters in the main intracranial arteries have large normal ranges. Reproducibility is highest in MCA. (orig.)

  12. Hyperelastic remodeling in the intrauterine growth restricted (IUGR) carotid artery in the near-term fetus.

    Science.gov (United States)

    Dodson, R Blair; Rozance, Paul J; Reina-Romo, Esther; Ferguson, Virginia L; Hunter, Kendall S

    2013-03-15

    A constitutive model for a fiber reinforced hyperelastic material was applied to understand arterial fiber remodeling in a sheep model of Intrauterine Growth Restriction (IUGR). IUGR is associated altered hemodynamics characterized by increased resistance to blood flow in the placenta and elevated fetal arterial pressure and pulsatility. The constitutive model describes the collagen contribution to the mechanics within the arterial wall in both control and IUGR carotid artery through defining the material modulus and the orientation of the microstructure. A sheep model of placental insufficiency induced IUGR (PI-IUGR) was created by exposure of the pregnant ewe to elevated ambient temperatures. Experimental data was collected using pressure-diameter measurements to measure passive compliance in control and PI-IUGR carotid arteries. The constitutive model was optimized to fit the experimental data predicting the material parameters. Specifically, the collagen fiber predicted angle (γ) in the control artery was 49.9° from the circumferential axis while the PI-IUGR was 16.6° with a 23.5% increase in fiber orientation (κ). Quantitative assessment of collagen fiber orientation in secondary harmonic generation images confirmed the shift in orientation between the two groups. Together these suggest vascular remodeling of the ECM fiber orientation plays a major role in arterial stiffening in the PI-IUGR near-term fetal sheep. Published by Elsevier Ltd.

  13. Measuring pH variability using an experimental sensor on an underwater glider

    Science.gov (United States)

    Hemming, Michael P.; Kaiser, Jan; Heywood, Karen J.; Bakker, Dorothee C. E.; Boutin, Jacqueline; Shitashima, Kiminori; Lee, Gareth; Legge, Oliver; Onken, Reiner

    2017-05-01

    Autonomous underwater gliders offer the capability of measuring oceanic parameters continuously at high resolution in both vertical and horizontal planes, with timescales that can extend to many months. An experimental ion-sensitive field-effect transistor (ISFET) sensor measuring pH on the total scale was attached to a glider during the REP14-MED experiment in June 2014 in the Sardinian Sea in the northwestern Mediterranean. During the deployment, pH was sampled at depths of up to 1000 m along an 80 km transect over a period of 12 days. Water samples were collected from a nearby ship and analysed for dissolved inorganic carbon concentration and total alkalinity to derive the pH for validating the ISFET sensor measurements. The vertical resolution of the pH sensor was good (1 to 2 m), but stability was poor and the sensor drifted in a non-monotonous fashion. In order to remove the sensor drift, a depth-constant time-varying offset was applied throughout the water column for each dive, reducing the spread of the data by approximately two-thirds. Furthermore, the ISFET sensor required temperature- and pressure-based corrections, which were achieved using linear regression. Correcting for this decreased the apparent sensor pH variability by a further 13 to 31 %. Sunlight caused an apparent sensor pH decrease of up to 0.1 in surface waters around local noon, highlighting the importance of shielding the sensor from light in future deployments. The corrected pH from the ISFET sensor is presented along with potential temperature, salinity, potential density anomalies (σθ), and dissolved oxygen concentrations (c(O2)) measured by the glider, providing insights into the physical and biogeochemical variability in the Sardinian Sea. The pH maxima were identified close to the depth of the summer chlorophyll maximum, where high c(O2) values were also found. Longitudinal pH variations at depth (σθ > 28. 8 kg m-3) highlighted the variability of water masses in the Sardinian

  14. Experimental measurements of U24Py nanocluster behavior in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Flynn, Shannon L.; Szymanowski, Jennifer E.S.; Fein, Jeremy B. [Univ. of Notre Dame, IN (United States). Department of Civil and Environmental Engineering and Earth Sciences; Dembowski, Mateusz [Univ. of Notre Dame, IN (United States). Department of Chemistry and Biochemistry; Burns, Peter C. [Univ. of Notre Dame, IN (United States). Department of Civil and Environmental Engineering and Earth Sciences; Univ. of Notre Dame, IN (United States). Department of Chemistry and Biochemistry

    2016-07-01

    Uranyl peroxide nanoclusters may impact the mobility and partitioning of uranium at contaminated sites and could be used in the isolation of uranium during the reprocessing of nuclear waste. Their behavior in aqueous systems must be better understood to predict the environmental fate of uranyl peroxide nanoclusters and for their use in engineered systems. The aqueous stability of only one uranyl peroxide nanocluster, U60 (K{sub 16}Li{sub 44}[UO{sub 2}(O{sub 2})OH]{sub 60}), has been studied to date [Flynn, S. L., Szymanowski, J. E. S., Gao, Y., Liu, T., Burns, P. C., Fein, J. B.: Experimental measurements of U60 nanocluster stability in aqueous solution. Geochemica et Cosmochimica Acta 156, 94-105 (2015)]. In this study, we measured the aqueous stability of a second uranyl peroxide nanocluster, U24Py (Na{sub 30}[(UO{sub 2}){sub 24}(O{sub 2}){sub 24}(HP{sub 2}O{sub 7}){sub 6}(H{sub 2}P{sub 2}O{sub 7}){sub 6}]), in batch systems as a function of time, pH, and nanocluster concentration, and then compared the aqueous behavior of U24Py to U60 to determine whether the size and morphology differences result in differences in their aqueous behaviors. Systems containing U24Py nanoclusters took over 30 days to achieve steady-state concentrations of monomeric U, Na, and P, illustrating slower reaction kinetics than parallel U60 systems. Furthermore, U24Py exhibited lower stability in solution than U60, with an average of 72% of the total mass in each nanocluster suspension being associated with the U24Py nanocluster, whereas 97% was associated with the U60 nanocluster in parallel experiments [Flynn, S. L., Szymanowski, J. E. S., Gao, Y., Liu, T., Burns, P. C., Fein, J. B.: Experimental measurements of U60 nanocluster stability in aqueous solution. Geochemica et Cosmochimica Acta 156, 94-105 (2015)]. The measurements from the batch experiments were used to calculate ion activity product (IAP) values for the reaction between the U24Py nanocluster and its constituent monomeric

  15. Immediate effects of cerebral ischemia: evolution and resolution of neurological deficits after experimental occlusion of one middle cerebral artery in conscious cats.

    Science.gov (United States)

    Hayakawa, T; Waltz, A G

    1975-01-01

    Acute occlusion of the left middle cerebral artery (MCA) was accomplished without anesthesia and inside an intact cranium containing cerebrospinal fluid (CSF) in ten cats five to nine days after implantation of an occlusive device through the orbit. Immediate neurological deficits included forced ambuxlation, circling, and tonic deviation of the head and neck toward the side of the occluded artery; weakness of the opposite limbs; and an apathetic or akinetic state. Two cats died within 24 hours. The other eight cats improved but secondary deficits developed in two, causing death. In two of the remaining six cats no deficits were apparent seven days later. The cerbral infarcts regularly involved the basal ganglia, internal capsule, and cortical regions, and were larger and less variable than those produced by MCA occlusion through and open optic foramen or craniectomy with cranial decompression by drainage of CSF. This model of acute focal cerebral ischemia may be of value for studies of physiological and biochemical factors uninfluenced by sedatives, anesthesia, or recent surgical procedures.

  16. The Numerical Calculation and Experimental Measurement of the Inductance Parameters for Permanent Magnet Synchronous Motor in Electric Vehicle

    Science.gov (United States)

    Jiang, Chao; Qiao, Mingzhong; Zhu, Peng

    2017-12-01

    A permanent magnet synchronous motor with radial magnetic circuit and built-in permanent magnet is designed for the electric vehicle. Finite element numerical calculation and experimental measurement are adopted to obtain the direct axis and quadrature axis inductance parameters of the motor which are vital important for the motor control. The calculation method is simple, the measuring principle is clear, the results of numerical calculation and experimental measurement are mutual confirmation. A quick and effective method is provided to obtain the direct axis and quadrature axis inductance parameters of the motor, and then improve the design of motor or adjust the control parameters of the motor controller.

  17. Opto-mechanical modelling and experimental approach to the measurement of aerospace materials using shearography and thermal loading

    Science.gov (United States)

    Corso Krutul, Eduardo; Groves, Roger M.

    2011-05-01

    This paper is concerned with the modelling of the complete opto-mechanical measurement system, including shearography instrument, loading technique and the response of the object under test and the comparison of the simulation results with experimental results. To show the applicability of this technique, the response of an aluminium flat plate sample under thermal load was analysed. First a finite element model of the plate was generated, using an experimentally measured temperature profile. The strain and displacement values obtained from the finite element model were used to simulate the phase-map in the optical part of the model. The simulated phase maps were then compared qualitatively with experimental phase maps measured using shearography. This approach is suitable to understand the response of components under load and to predict anoma