Sample records for wall thickness ratio

  1. Local and systemic effects of leg cycling training on arterial wall thickness in healthy humans.

    PubMed

    Thijssen, Dick H J; Dawson, Ellen A; van den Munckhof, Inge C L; Birk, Gurpreet K; Timothy Cable, N; Green, Daniel J

    2013-08-01

    Exercise training is associated with direct effects on conduit artery function and structure. Cross-sectional studies suggest the presence of systemic changes in wall thickness as a result of exercise in healthy subjects, but no previous study has examined this question in humans undertaking exercise training. To examine the change in superficial femoral (SFA, i.e. local effect) and carotid (CA, i.e. systemic effect) artery wall thickness across 8 weeks of lower limb cycle training in healthy young men. Fourteen healthy young male subjects were assigned to an 8-week training study of cycling exercise (n = 9) or a control period (n = 5). Before, during (2, 4 and 6 weeks) and after training, SFA and CA wall thickness was examined using automated edge-detection of high resolution ultrasound images. We also measured resting diameter and calculated the wall:lumen(W:L)-ratio. Exercise training did not alter CA or SFA baseline diameter (P = 0.14), but was associated with gradual, consistent and significant decreases in wall thickness and W:L-ratio in both the CA and SFA (P < 0.001 and 0.002, respectively). Two-way ANOVA revealed a comparable magnitude of decrease in wall thickness and W:L-ratio in both arteries across the 8-week period (interaction-effect; P = 0.29 and 0.12, respectively). No changes in artery diameter, wall thickness or W:L-ratio were apparent in controls (0.82, 0.38 and 0.52, respectively). We found that cycle exercise training in healthy young individuals is associated with modest, but significant, decreases in wall thickness in the superficial femoral and carotid arteries. These findings suggest that exercise training causes systemic adaptation of the arterial wall in healthy young subjects. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  2. The Bulging Behavior of Thick-Walled 6063 Aluminum Alloy Tubes Under Double-Sided Pressures

    NASA Astrophysics Data System (ADS)

    Cui, Xiao-Lei; Wang, Xiao-Song; Yuan, Shi-Jian

    2015-05-01

    To make further exploration on the deformation behavior of tube under double-sided pressures, the thick-walled 6063 aluminum alloy tubes with an outer diameter of 65 mm and an average thickness of 7.86 mm have been used to be bulged under the combined action of internal and external pressures. In the experiment, two ends of the thick-walled tubes were fixed using the tooth and groove match. Three levels of external pressure (0 MPa, 40 MPa, and 80 MPa), in conjunction with the internal pressure, were applied on the tube outside and inside simultaneously. The effect of external pressure on the bulging behavior of the thick-walled tubes, such as the limiting expansion ratio, the bulging zone profile, and the thickness distribution, has been investigated. It is shown that the limiting expansion ratio, the bulging zone profile, and the thickness distribution in the homogeneous bulging area are all insensitive to the external pressure. However, the external pressure can make the thick-walled tube achieve a thinner wall at the fracture area. It reveals that the external pressure can only improve the fracture limit of the thick-walled 6063 tubes, but it has very little effect on their homogeneous bulging behavior. It might be because the external pressure can only increase the magnitude of the hydrostatic pressure for the tube but has no effect on the Lode parameter.

  3. Pulse wave velocity as a diagnostic index: The effect of wall thickness

    NASA Astrophysics Data System (ADS)

    Hodis, Simona

    2018-06-01

    Vascular compliance is a major determinant of wave propagation within the vascular system, and hence the measurement of pulse wave velocity (PWV) is commonly used clinically as a method of detecting vascular stiffening. The accuracy of that assessment is important because vascular stiffening is a major risk factor for hypertension. PWV is usually measured by timing a pressure wave as it travels from the carotid artery to the femoral or radial artery and estimating the distance that it traveled in each case to obtain the required velocity. A major assumption on which this technique is based is that the vessel wall thickness h is negligibly small compared with the vessel radius a . The extent to which this assumption is satisfied in the cardiovascular system is not known because the ratio h /a varies widely across different regions of the vascular tree and under different pathological conditions. Using the PWV as a diagnostic test without knowing the effect of wall thickness on the measurement could lead to error when interpreting the PWV value as an index of vessel wall compliance. The aim of the present study was to extend the validity of the current practice of assessing wall stiffness by developing a method of analysis that goes beyond the assumption of a thin wall. We analyzed PWVs calculated with different wall models, depending on the ratio of wall thickness to vessel radius and the results showed that PWV is not reliable when it is estimated with the classic thin wall theory if the vessel wall is not around 25% of vessel radius. If the arterial wall is thicker than 25% of vessel radius, then the wave velocity calculated with the thin wall theory could be overestimated and in the clinical setting, this could lead to a false positive. For thicker walls, a thick wall model presented here should be considered to account for the stresses within the wall thickness that become dominant compared with the wall inertia.

  4. Turbine airfoil with outer wall thickness indicators

    DOEpatents

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

    2013-08-06

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

  5. Method and apparatus for determining diameter and wall thickness of minute hollow spherical shells

    DOEpatents

    Steinman, D.A.

    1980-05-30

    Method and apparatus for determining diameter and wall thickness of hollow microspheres or shells wherein terminal velocities of shells traveling in fluid-filled conduits of differing diameters are measured. A wall-effect factor is determined as a ratio of the terminal velocities, and shell outside diameter may then be ascertained as a predetermined empirical function of wall-effect factor. For shells of known outside diameter, wall thickness may then be ascertained as a predetermined empirical function of terminal velocity in either conduit.

  6. Method and apparatus for determining diameter and wall thickness of minute hollow spherical shells

    DOEpatents

    Steinman, David A.

    1982-01-01

    Method and apparatus for determining diameter and wall thickness of hollow microspheres or shells wherein terminal velocities of shells traveling in fluid-filled conduits of differing diameters are measured. A wall-effect factor is determined as a ratio of the terminal velocities, and shell outside diameter may then be ascertained as a predetermined empirical function of wall-effect factor. For shells of known outside diameter, wall thickness may then be ascertained as a predetermined empirical function of terminal velocity in either conduit.

  7. Tube wall thickness measurement apparatus

    DOEpatents

    Lagasse, P.R.

    1985-06-21

    An apparatus for measuring the thickness of a tube's wall for the tube's entire length and radius by determining the deviation of the tube wall thickness from the known thickness of a selected standard item. The apparatus comprises a base and a first support member having first and second ends. The first end is connected to the base and the second end is connected to a spherical element. A second support member is connected to the base and spaced apart from the first support member. A positioning element is connected to and movable relative to the second support member. An indicator is connected to the positioning element and is movable to a location proximate the spherical element. The indicator includes a contact ball for first contacting the selected standard item and holding it against the spherical element. The contact ball then contacts the tube when the tube is disposed about the spherical element. The indicator includes a dial having a rotatable needle for indicating the deviation of the tube wall thickness from the thickness of the selected standard item.

  8. Tube wall thickness measurement apparatus

    DOEpatents

    Lagasse, Paul R.

    1987-01-01

    An apparatus for measuring the thickness of a tube's wall for the tube's entire length and circumference by determining the deviation of the tube wall thickness from the known thickness of a selected standard item. The apparatus comprises a base and a first support member having first and second ends. The first end is connected to the base and the second end is connected to a spherical element. A second support member is connected to the base and spaced apart from the first support member. A positioning element is connected to and movable relative to the second support member. An indicator is connected to the positioning element and is movable to a location proximate the spherical element. The indicator includes a contact ball for first contacting the selected standard item and holding it against the spherical element. The contact ball then contacts the tube when the tube is disposed about the spherical element. The indicator includes a dial having a rotatable needle for indicating the deviation of the tube wall thickness from the thickness of the selected standard item.

  9. Automated airway evaluation system for multi-slice computed tomography using airway lumen diameter, airway wall thickness and broncho-arterial ratio

    NASA Astrophysics Data System (ADS)

    Odry, Benjamin L.; Kiraly, Atilla P.; Novak, Carol L.; Naidich, David P.; Lerallut, Jean-Francois

    2006-03-01

    Pulmonary diseases such as bronchiectasis, asthma, and emphysema are characterized by abnormalities in airway dimensions. Multi-slice computed tomography (MSCT) has become one of the primary means to depict these abnormalities, as the availability of high-resolution near-isotropic data makes it possible to evaluate airways at oblique angles to the scanner plane. However, currently, clinical evaluation of airways is typically limited to subjective visual inspection only: systematic evaluation of the airways to take advantage of high-resolution data has not proved practical without automation. We present an automated method to quantitatively evaluate airway lumen diameter, wall thickness and broncho-arterial ratios. In addition, our method provides 3D visualization of these values, graphically illustrating the location and extent of disease. Our algorithm begins by automatic airway segmentation to extract paths to the distal airways, and to create a map of airway diameters. Normally, airway diameters decrease as paths progress distally; failure to taper indicates abnormal dilatation. Our approach monitors airway lumen diameters along each airway path in order to detect abnormal profiles, allowing even subtle degrees of pathologic dilatation to be identified. Our method also systematically computes the broncho-arterial ratio at every terminal branch of the tree model, as a ratio above 1 indicates potentially abnormal bronchial dilatation. Finally, the airway wall thickness is computed at corresponding locations. These measurements are used to highlight abnormal branches for closer inspection, and can be summed to compute a quantitative global score for the entire airway tree, allowing reproducible longitudinal assessment of disease severity. Preliminary tests on patients diagnosed with bronchiectasis demonstrated rapid identification of lack of tapering, which also was confirmed by corresponding demonstration of elevated broncho-arterial ratios.

  10. Ultrasonographic wall thickness measurement of the upper and lower uterine segments in the prediction of the progress of preterm labour.

    PubMed

    Sayed Ahmed, W A; Madny, E H; Habash, Y H; Ibrahim, Z M; Morsy, A G K; Said, M E

    2015-01-01

    To assess the role of ultrasonographic measurement of the upper and lower uterine segments wall thickness in predicting the progress of preterm labour in patients presenting with preterm labour pains. Fifty pregnant women presenting at Obstetrics Department - Suez Canal University, Egypt with regular lower abdominal pains and diagnosed as having preterm labour were enrolled in the study. Measurements of the upper and lower uterine segments wall thickness by transabdominal ultrasonography in-between contractions and with full bladder were taken. The upper/lower uterine wall thickness ratio was calculated and correlated to the progress of the preterm labour and to the response to tocolytics. The ultrasonographic upper/lower uterine wall thickness ratio was directly related to the progress of preterm delivery (PTD). The change in this ratio is correlated inversely with the response to tocolysis. Using the ROC curve, when the upper/lower uterine wall thickness ratio was ≤ 1.26 the sensitivity was 94.74 and the specificity was 100.00, and when the ratio was ≤ 1.52 the sensitivity was 100.00 and the specificity was 83.33. These data may serve as a baseline ultrasonographic reference values for further studies in prediction the progress of preterm labour in patients presenting with preterm labour pains.

  11. Wall thickness measuring method and apparatus

    DOEpatents

    Salzer, Leander J.; Bergren, Donald A.

    1989-01-01

    An apparatus for measuring the wall thickness of a nonmagnetic article having a housing supporting a magnet and a contiguous supporting surface. The tubular article and the housing are releasably secured to the supporting surface and a support member of an optical comparator, respectively. To determine the wall thickness of the article at a selected point, a magnetically responsive ball is positioned within the tubular article over said point and retained therein by means of a magnetic field produced by the magnet. Thereafter, an optical comparator is employed to project a magnified image of the ball on a screen and the wall thickness at the selected point is calculated by using a ball surface measurement taken with the comparator in conjunction with a previously determined base line measurement.

  12. Wall thickness measuring method and apparatus

    DOEpatents

    Salzer, L.J.; Bergren, D.A.

    1987-10-06

    An apparatus for measuring the wall thickness of a nonmagnetic article having a housing supporting a magnet and a contiguous supporting surface. The tubular article and the housing are releasably secured to the supporting surface and a support member of an optical comparator, respectively. To determine the wall thickness of the article at a selected point, a magnetically responsive ball is positioned within the tubular article over said point and retained therein by means of a magnetic field produced by the magnet. Thereafter, an optical comparator is employed to project a magnified image of the ball on a screen and the wall thickness at the selected point is calculated by using a ball surface measurement taken with the comparator in conjunction with a previously determined base line measurement.

  13. Measurement of retinal wall-to-lumen ratio by adaptive optics retinal camera: a clinical research.

    PubMed

    Meixner, Eva; Michelson, Georg

    2015-11-01

    To measure the wall-to-lumen ratio (WLR) and the cross-sectional area of the vascular wall (WCSA) of retinal arterioles by an Adaptive Optics (AO) retinal camera. Forty-seven human subjects were examined and their medical history was explored. WLR and WCSA were measured on the basis of retinal arteriolar wall thickness (VW), lumen diameter (LD) and vessel diameter (VD) assessed by rtx1 Adaptive Optics retinal camera. WLR was calculated by the formula [Formula: see text]. Arterio-venous ratio (AVR) and microvascular abnormalities were attained by quantitative and qualitative assessment of fundus photographs. Influence of age, arterial hypertension, body mass index (BMI) and retinal microvascular abnormalities on the WLR was examined. An age-adjusted WLR was created to test influences on WLR independently of age. Considering WLR and WCSA, a distinction between eutrophic and hypertrophic retinal remodeling processes was possible. The intra-observer variability (IOV) was 6 % ± 0.9 for arteriolar wall thickness and 2 % ± 0.2 for arteriolar wall thickness plus vessel lumen. WLR depended significantly on the wall thickness (r = 0.715; p < 0.01) of retinal arterioles, but was independent of the total vessel diameter (r = 0.052; p = 0.728). WLR correlated significantly with age (r = 0.769; p < 0.01). Arterial hypertension and a higher BMI were significantly associated with an increased age-adjusted WLR. WLR correlated significantly with the stage of microvascular abnormalities. 55 % of the hypertensive subjects and 11 % of the normotensive subjects showed eutrophic remodeling, while hypertrophic remodeling was not detectable. WLR correlated inversely with AVR. AVR was independent of the arteriolar wall thickness, age and arterial hypertension. The technique of AO retinal imaging allows a direct measurement of the retinal vessel wall and lumen diameter with good intra-observer variability. Age, arterial hypertension and an elevated BMI level

  14. A pilot study on bladder wall thickness at different filling stages

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Liu, Yang; Li, Baojuan; Zhang, Guopeng; Liang, Zhengrong; Lu, Hongbing

    2015-03-01

    The ever-growing death rate and the high recurrence of bladder cancer make the early detection and appropriate followup procedure of bladder cancer attract more attention. Compare to optical cystoscopy, image-based studies have revealed its potentials in non-invasive observations of the abnormities of bladder recently, in which MR imaging turns out to be a better choice for bladder evaluation due to its non-ionizing and high contrast between urine and wall tissue. Recent studies indicate that bladder wall thickness tends to be a good indicator for detecting bladder wall abnormalities. However, it is difficult to quantitatively compare wall thickness of the same subject at different filling stages or among different subjects. In order to explore thickness variations at different bladder filling stages, in this study, we preliminarily investigate the relationship between bladder wall thickness and bladder volume based on a MRI database composed of 40 datasets acquired from 10 subjects at different filling stages, using a pipeline for thickness measurement and analysis proposed in our previous work. The Student's t-test indicated that there was no significant different on wall thickness between the male group and the female group. The Pearson correlation analysis result indicated that negative correlation with a correlation coefficient of -0.8517 existed between the wall thickness and bladder volume, and the correlation was significant(p <0.01). The corresponding linear regression equation was then estimated by the unary linear regression. Compared to the absolute value of wall thickness, the z-score of wall thickness would be more appropriate to reflect the thickness variations. For possible abnormality detection of a bladder based on wall thickness, the intra-subject and inter-subject thickness variation should be considered.

  15. Impact of wall thickness and saccular geometry on the computational wall stress of descending thoracic aortic aneurysms.

    PubMed

    Shang, Eric K; Nathan, Derek P; Sprinkle, Shanna R; Fairman, Ronald M; Bavaria, Joseph E; Gorman, Robert C; Gorman, Joseph H; Jackson, Benjamin M

    2013-09-10

    Wall stress calculated using finite element analysis has been used to predict rupture risk of aortic aneurysms. Prior models often assume uniform aortic wall thickness and fusiform geometry. We examined the effects of including local wall thickness, intraluminal thrombus, calcifications, and saccular geometry on peak wall stress (PWS) in finite element analysis of descending thoracic aortic aneurysms. Computed tomographic angiography of descending thoracic aortic aneurysms (n=10 total, 5 fusiform and 5 saccular) underwent 3-dimensional reconstruction with custom algorithms. For each aneurysm, an initial model was constructed with uniform wall thickness. Experimental models explored the addition of variable wall thickness, calcifications, and intraluminal thrombus. Each model was loaded with 120 mm Hg pressure, and von Mises PWS was computed. The mean PWS of uniform wall thickness models was 410 ± 111 kPa. The imposition of variable wall thickness increased PWS (481 ± 126 kPa, P<0.001). Although the addition of calcifications was not statistically significant (506 ± 126 kPa, P=0.07), the addition of intraluminal thrombus to variable wall thickness (359 ± 86 kPa, P ≤ 0.001) reduced PWS. A final model incorporating all features also reduced PWS (368 ± 88 kPa, P<0.001). Saccular geometry did not increase diameter-normalized stress in the final model (77 ± 7 versus 67 ± 12 kPa/cm, P=0.22). Incorporation of local wall thickness can significantly increase PWS in finite element analysis models of thoracic aortic aneurysms. Incorporating variable wall thickness, intraluminal thrombus, and calcifications significantly impacts computed PWS of thoracic aneurysms; sophisticated models may, therefore, be more accurate in assessing rupture risk. Saccular aneurysms did not demonstrate a significantly higher normalized PWS than fusiform aneurysms.

  16. Effects of finite wall thickness and sinusoidal heating on convection in nanofluid-saturated local thermal non-equilibrium porous cavity

    NASA Astrophysics Data System (ADS)

    Alsabery, A. I.; Chamkha, A. J.; Saleh, H.; Hashim, I.; Chanane, B.

    2017-03-01

    The effects of finite wall thickness and sinusoidal heating on convection in a nanofluid-saturated local thermal non-equilibrium (LTNE) porous cavity are studied numerically using the finite difference method. The finite thickness vertical wall of the cavity is maintained at a constant temperature and the right wall is heated sinusoidally. The horizontal insulated walls allow no heat transfer to the surrounding. The Darcy law is used along with the Boussinesq approximation for the flow. Water-based nanofluids with Cu nanoparticles are chosen for investigation. The results of this study are obtained for various parameters such as the Rayleigh number, periodicity parameter, nanoparticles volume fraction, thermal conductivity ratio, ratio of wall thickness to its height and the modified conductivity ratio. Explanation for the influence of the various above-mentioned parameters on the streamlines, isotherms, local Nusselt number and the weighted average heat transfer is provided with regards to the thermal conductivities of nanoparticles suspended in the pure fluid and the porous medium. It is shown that the overall heat transfer is significantly increased with the relative non-uniform heating. Further, the convection heat transfer is shown to be inhibited by the presence of the solid wall. The results have possible applications in the heat-storage fluid-saturated porous systems and the applications of the high power heat transfer.

  17. 49 CFR 192.109 - Nominal wall thickness (t) for steel pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Nominal wall thickness (t) for steel pipe. 192.109 Section 192.109 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND... Nominal wall thickness (t) for steel pipe. (a) If the nominal wall thickness for steel pipe is not known...

  18. 49 CFR 192.109 - Nominal wall thickness (t) for steel pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Nominal wall thickness (t) for steel pipe. 192.109 Section 192.109 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND... Nominal wall thickness (t) for steel pipe. (a) If the nominal wall thickness for steel pipe is not known...

  19. 49 CFR 192.109 - Nominal wall thickness (t) for steel pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Nominal wall thickness (t) for steel pipe. 192.109 Section 192.109 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND... Nominal wall thickness (t) for steel pipe. (a) If the nominal wall thickness for steel pipe is not known...

  20. 49 CFR 192.109 - Nominal wall thickness (t) for steel pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Nominal wall thickness (t) for steel pipe. 192.109 Section 192.109 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND... Nominal wall thickness (t) for steel pipe. (a) If the nominal wall thickness for steel pipe is not known...

  1. 49 CFR 192.109 - Nominal wall thickness (t) for steel pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Nominal wall thickness (t) for steel pipe. 192.109 Section 192.109 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND... Nominal wall thickness (t) for steel pipe. (a) If the nominal wall thickness for steel pipe is not known...

  2. Vesicular thick-walled swollen hyphae in pulmonary zygomycosis.

    PubMed

    Kimura, Masatomo; Ito, Hiroyuki

    2009-03-01

    An autopsy case of pulmonary zygomycosis in a patient with rheumatoid arthritis on immunosuppressive therapy is presented herein. There was a pulmonary cavitated infarct caused by mycotic thrombosis. Thin-walled narrow hyphae and vesicular thick-walled swollen hyphae were found on the pleural surface and in the necrotic tissue at the periphery of the cavity. Findings of such shaped fungal elements may cause erroneous histopathological diagnosis because pauciseptate broad thin-walled hyphae are usually the only detectable fungal elements in zygomycosis tissue. Although immunohistochemistry confirmed these unusual elements to be zygomycetous in the present case, it is important for the differential diagnosis to be aware that zygomycetes can form thin narrow hyphae and vesicular thick-walled swollen hyphae.

  3. Assessment of bronchial wall thickness and lumen diameter in human adults using multi-detector computed tomography: comparison with theoretical models

    PubMed Central

    Montaudon, M; Desbarats, P; Berger, P; de Dietrich, G; Marthan, R; Laurent, F

    2007-01-01

    A thickened bronchial wall is the morphological substratum of most diseases of the airway. Theoretical and clinical models of bronchial morphometry have so far focused on bronchial lumen diameter, and bronchial length and angles, mainly assessed from bronchial casts. However, these models do not provide information on bronchial wall thickness. This paper reports in vivo values of cross-sectional wall area, lumen area, wall thickness and lumen diameter in ten healthy subjects as assessed by multi-detector computed tomography. A validated dedicated software package was used to measure these morphometric parameters up to the 14th bronchial generation, with respect to Weibel's model of bronchial morphometry, and up to the 12th according to Boyden's classification. Measured lumen diameters and homothety ratios were compared with theoretical values obtained from previously published studies, and no difference was found when considering dichotomic division of the bronchial tree. Mean wall area, lumen area, wall thickness and lumen diameter were then provided according to bronchial generation order, and mean homothety ratios were computed for wall area, lumen area and wall thickness as well as equations giving the mean value of each parameter for a given bronchial generation with respect to its value in generation 0 (trachea). Multi-detector computed tomography measurements of bronchial morphometric parameters may help to improve our knowledge of bronchial anatomy in vivo, our understanding of the pathophysiology of bronchial diseases and the evaluation of pharmacological effects on the bronchial wall. PMID:17919291

  4. Average chest wall thickness at two anatomic locations in trauma patients.

    PubMed

    Schroeder, Elizabeth; Valdez, Carrie; Krauthamer, Andres; Khati, Nadia; Rasmus, Jessica; Amdur, Richard; Brindle, Kathleen; Sarani, Babak

    2013-09-01

    Needle thoracostomy is the emergent treatment for tension pneumothorax. This procedure is commonly done using a 4.5cm catheter, and the optimal site for chest wall puncture is controversial. We hypothesize that needle thoracostomy cannot be performed using this catheter length irrespective of the site chosen in either gender. A retrospective review of all chest computed tomography (CT) scans obtained on trauma patients from January 1, 2011 to December 31, 2011 was performed. Patients aged 18 and 80 years were included and patients whose chest wall thickness exceeded the boundary of the images acquired were excluded. Chest wall thickness was measured at the 2nd intercostal (ICS), midclavicular line (MCL) and the 5th ICS, anterior axillary line (AAL). Injury severity score (ISS), chest wall thickness, and body mass index (BMI) were analyzed. 201 patients were included, 54% male. Average (SD) BMI was 26 (7)kg/m(2). The average chest wall thickness in the overall cohort was 4.08 (1.4)cm at the 2nd ICS/MCL and 4.55 (1.7)cm at the 5th ICS/AAL. 29% of the overall cohort (27 male and 32 female) had a chest wall thickness greater than 4.5cm at the 2nd ICS/MCL and 45% (54 male and 36 female) had a chest wall thickness greater than 4.5cm at the 5th ICS/AAL. There was no significant interaction between gender and chest wall thickness at either site. BMI was positively associated with chest wall thickness at both the 2nd and 5th ICS/AAL. A 4.5cm catheter is inadequate for needle thoracostomy in most patients regardless of puncture site or gender. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Analysis of the effects of gravity and wall thickness in a model of blood flow through axisymmetric vessels.

    PubMed

    Payne, S J

    2004-11-01

    The effects of gravitational forces and wall thickness on the behaviour of a model of blood flow through axisymmetric vessels were studied. The governing fluid dynamic equations were derived from the Navier-Stokes equations for an incompressible fluid and linked to a simple model of the vessel wall. A closed form of the hyperbolic partial differential equations was found, including a significant source term from the gravitational forces. The inclination of the vessel is modelled using a slope parameter that varied between -1 and 1. The wave speed was shown to be related to the wall thickness, and the time to first shock formation was shown to be directly proportional to this thickness. Two non-dimensional parameters were derived for the ratio of gravitational forces to viscous and momentum forces, respectively, and their values were calculated for the different types of vessel found in the human vasculature, showing that gravitational forces were significant in comparison with either viscous or momentum forces for every type of vessel. The steady-state solution of the governing equations showed that gravitational forces cause an increase in area of approximately 5% per metre per unit slope. Numerical simulations of the flow field in the aorta showed that a positive slope causes a velocity pulse to change in amplitude approximately linearly with distance: -4% per metre and +5% per metre for vessels inclined vertically upwards and downwards, respectively, in comparison with only +0.5% for a horizontal vessel. These simulations also showed that the change relative to the zero slope condition in the maximum rate of change of area with distance, which was taken to be a measure of the rate of shock formation, is proportional to both the slope and the wall thickness-to-inner radius ratio, with a constant of proportionality of 1.2. At a ratio of 0.25, typical of that found in human arteries, the distance to shock formation is thus decreased and increased by 30% for vessels

  6. Normal reference values for bladder wall thickness on CT in a healthy population.

    PubMed

    Fananapazir, Ghaneh; Kitich, Aleksandar; Lamba, Ramit; Stewart, Susan L; Corwin, Michael T

    2018-02-01

    To determine normal bladder wall thickness on CT in patients without bladder disease. Four hundred and nineteen patients presenting for trauma with normal CTs of the abdomen and pelvis were included in our retrospective study. Bladder wall thickness was assessed, and bladder volume was measured using both the ellipsoid formula and an automated technique. Patient age, gender, and body mass index were recorded. Linear regression models were created to account for bladder volume, age, gender, and body mass index, and the multiple correlation coefficient with bladder wall thickness was computed. Bladder volume and bladder wall thickness were log-transformed to achieve approximate normality and homogeneity of variance. Variables that did not contribute substantively to the model were excluded, and a parsimonious model was created and the multiple correlation coefficient was calculated. Expected bladder wall thickness was estimated for different bladder volumes, and 1.96 standard deviation above expected provided the upper limit of normal on the log scale. Age, gender, and bladder volume were associated with bladder wall thickness (p = 0.049, 0.024, and < 0.001, respectively). The linear regression model had an R 2 of 0.52. Age and gender were negligible in contribution to the model, and a parsimonious model using only volume was created for both the ellipsoid and automated volumes (R 2  = 0.52 and 0.51, respectively). Bladder wall thickness correlates with bladder wall volume. The study provides reference bladder wall thicknesses on CT utilizing both the ellipsoid formula and automated bladder volumes.

  7. Gas turbine bucket wall thickness control

    DOEpatents

    Stathopoulos, Dimitrios; Xu, Liming; Lewis, Doyle C.

    2002-01-01

    A core for use in casting a turbine bucket including serpentine cooling passages is divided into two pieces including a leading edge core section and a trailing edge core section. Wall thicknesses at the leading edge and the trailing edge of the turbine bucket can be controlled independent of each other by separately positioning the leading edge core section and the trailing edge core section in the casting die. The controlled leading and trailing edge thicknesses can thus be optimized for efficient cooling, resulting in more efficient turbine operation.

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

    PubMed Central

    Dong, Ding-Hui; Liu, Wen-Yan; Feng, Hai-Bo; Fu, Yi-Li; Huang, Shi; Xiang, Jun-Xi; Lyu, Yi

    2015-01-01

    Background: Magnetic anchored surgical instruments (MASI), relying on magnetic force, can break through the limitations of the single port approach in dexterity. Individual characteristic abdominal wall thickness (ICAWT) deeply influences magnetic force that determines the safety of MASI. The purpose of this study was to research the abdominal wall characteristics in MASI applied environment to find ICAWT, and then construct an artful method to predict ICAWT, resulting in better safety and feasibility for MASI. Methods: For MASI, ICAWT is referred to the thickness of thickest point in the applied environment. We determined ICAWT through finding the thickest point in computed tomography scans. We also investigated the traits of abdominal wall thickness to discover the factor that can be used to predict ICAWT. Results: Abdominal wall at C point in the middle third lumbar vertebra plane (L3) is the thickest during chosen points. Fat layer thickness plays a more important role in abdominal wall thickness than muscle layer thickness. “BMI-ICAWT” curve was obtained based on abdominal wall thickness of C point in L3 plane, and the expression was as follow: f(x) = P1 × x2 + P2 × x + P3, where P1 = 0.03916 (0.01776, 0.06056), P2 = 1.098 (0.03197, 2.164), P3 = −18.52 (−31.64, −5.412), R-square: 0.99. Conclusions: Abdominal wall thickness of C point at L3 could be regarded as ICAWT. BMI could be a reliable predictor of ICAWT. In the light of “BMI-ICAWT” curve, we may conveniently predict ICAWT by BMI, resulting a better safety and feasibility for MASI. PMID:26228215

  9. Evolution of thick domain walls in de Sitter universe

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dolgov, A.D.; Godunov, S.I.; Rudenko, A.S., E-mail: dolgov@fe.infn.it, E-mail: sgodunov@itep.ru, E-mail: a.s.rudenko@inp.nsk.su

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

  10. Influence of the internal wall thickness of electrical capacitance tomography sensors on image quality

    NASA Astrophysics Data System (ADS)

    Liang, Shiguo; Ye, Jiamin; Wang, Haigang; Wu, Meng; Yang, Wuqiang

    2018-03-01

    In the design of electrical capacitance tomography (ECT) sensors, the internal wall thickness can vary with specific applications, and it is a key factor that influences the sensitivity distribution and image quality. This paper will discuss the effect of the wall thickness of ECT sensors on image quality. Three flow patterns are simulated for wall thicknesses of 2.5 mm to 15 mm on eight-electrode ECT sensors. The sensitivity distributions and potential distributions are compared for different wall thicknesses. Linear back-projection and Landweber iteration algorithms are used for image reconstruction. Relative image error and correlation coefficients are used for image evaluation using both simulation and experimental data.

  11. Enhancing cell-free layer thickness by bypass channels in a wall.

    PubMed

    Saadatmand, M; Shimogonya, Y; Yamaguchi, T; Ishikawa, T

    2016-07-26

    When blood flows near a wall, red blood cells (RBCs) drift away from the wall and a cell-free layer (CFL) is formed adjacent to the wall. Controlling the CFL thickness is important for preventing adhesion of cells in the design of biomedical devices. In this study, a novel wall configuration with stenoses and bypass channels is proposed to increase the CFL thickness. We found that the presence of bypass channels modified the spatial distribution of cells and substantially increased the CFL downstream of the stenosis. A single-bypass geometry with 5% hematocrit (Hct) blood flow showed a 1.7μm increase in CFL thickness compared to without the bypass. In the case of three bypass channels, a 3μm increase in CFL thickness was observed. The CFL enhancement was observed up to 10% Hct, but no significant enhancement of CFL was indicated for 20% Hct blood flow. The mechanism of the CFL enhancement was investigated using a numerical simulation of the flow field. The results showed that the distance between each streamline and the corner of the stenosis compared with size of RBC was important parameter in regulating CFL thickness. These results show the potential of the proposed mechanism to prevent adhesion of cells to biomedical devices. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. On thick domain walls in general relativity

    NASA Technical Reports Server (NTRS)

    Goetz, Guenter; Noetzold, Dirk

    1989-01-01

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

  13. A Probabilistic Method for Estimation of Bowel Wall Thickness in MR Colonography

    PubMed Central

    Menys, Alex; Jaffer, Asif; Bhatnagar, Gauraang; Punwani, Shonit; Atkinson, David; Halligan, Steve; Hawkes, David J.; Taylor, Stuart A.

    2017-01-01

    MRI has recently been applied as a tool to quantitatively evaluate the response to therapy in patients with Crohn’s disease, and is the preferred choice for repeated imaging. Bowel wall thickness on MRI is an important biomarker of underlying inflammatory activity, being abnormally increased in the acute phase and reducing in response to successful therapy; however, a poor level of interobserver agreement of measured thickness is reported and therefore a system for accurate, robust and reproducible measurements is desirable. We propose a novel method for estimating bowel wall-thickness to improve the poor interobserver agreement of the manual procedure. We show that the variability of wall thickness measurement between the algorithm and observer measurements (0.25mm ± 0.81mm) has differences which are similar to observer variability (0.16mm ± 0.64mm). PMID:28072831

  14. Incidence of non-pulmonary cancer and lung cancer by amount of emphysema and airway wall thickness: a community-based cohort.

    PubMed

    Aamli Gagnat, Ane; Gjerdevik, Miriam; Gallefoss, Frode; Coxson, Harvey O; Gulsvik, Amund; Bakke, Per

    2017-05-01

    There is limited knowledge about the prognostic value of quantitative computed tomography (CT) measures of emphysema and airway wall thickness in cancer.The aim of this study was to investigate if using CT to quantitatively assess the amount of emphysema and airway wall thickness independently predicts the subsequent incidence of non-pulmonary cancer and lung cancer.In the GenKOLS study of 2003-2005, 947 ever-smokers performed spirometry and underwent CT examination. The main predictors were the amount of emphysema measured by the percentage of low attenuation areas (%LAA) on CT and standardised measures of airway wall thickness (AWT-PI10). Cancer data from 2003-2013 were obtained from the Norwegian Cancer Register. The hazard ratio associated with emphysema and airway wall thickness was assessed using Cox proportional hazards regression for cancer diagnoses.During 10 years of follow-up, non-pulmonary cancer was diagnosed in 11% of the subjects with LAA <3%, in 19% of subjects with LAA 3-10%, and in 17% of subjects with LAA ≥10%. Corresponding numbers for lung cancer were 2%, 3% and 11%, respectively. After adjustment, the baseline amount of emphysema remained a significant predictor of the incidence of non-pulmonary cancer and lung cancer. Airway wall thickness did not predict cancer independently.This study offers a strong argument that emphysema is an independent risk factor for both non-pulmonary cancer and lung cancer. Copyright ©ERS 2017.

  15. Contribution of CT quantified emphysema, air trapping and airway wall thickness on pulmonary function in male smokers with and without COPD.

    PubMed

    Mohamed Hoesein, Firdaus A A; de Jong, Pim A; Lammers, Jan-Willem J; Mali, Willem P Th M; Mets, Onno M; Schmidt, Michael; de Koning, Harry J; Aalst, Carlijn van der; Oudkerk, Matthijs; Vliegenthart, Rozemarijn; Ginneken, Bram van; van Rikxoort, Eva M; Zanen, Pieter

    2014-09-01

    Emphysema, airway wall thickening and air trapping are associated with chronic obstructive pulmonary disease (COPD). All three can be quantified by computed tomography (CT) of the chest. The goal of the current study is to determine the relative contribution of CT derived parameters on spirometry, lung volume and lung diffusion testing. Emphysema, airway wall thickening and air trapping were quantified automatically on CT in 1,138 male smokers with and without COPD. Emphysema was quantified by the percentage of voxels below -950 Hounsfield Units (HU), airway wall thickness by the square root of wall area for a theoretical airway with 10 mm lumen perimeter (Pi10) and air trapping by the ratio of mean lung density at expiration and inspiration (E/I-ratio). Spirometry, residual volume to total lung capacity (RV/TLC) and diffusion capacity (Kco) were obtained. Standardized regression coefficients (β) were used to analyze the relative contribution of CT changes to pulmonary function measures. The independent contribution of the three CT measures differed per lung function parameter. For the FEV1 airway wall thickness was the most contributing structural lung change (β = -0.46), while for the FEV1/FVC this was emphysema (β = -0.55). For the residual volume (RV) air trapping was most contributing (β = -0.35). Lung diffusion capacity was most influenced by emphysema (β = -0.42). In a cohort of smokers with and without COPD the effect of different CT changes varies per lung function measure and therefore emphysema, airway wall thickness and air trapping need to be taken in account.

  16. The ratioed image film thickness meter

    NASA Astrophysics Data System (ADS)

    Husen, Nicholas M.; Liu, Tianshu; Sullivan, John P.

    2018-06-01

    A technique for measuring the thickness of a fluorescent oil film is presented. Incident light is cast upon the oil film and the intensity of the luminescent signal from the fluorescent dye is ratioed with the intensity of the incident light which is scattered from the surface of the model. The quotient is independent of the intensity of the incident light and proportional to the film thickness. Experiments are presented supporting that for sufficiently thin films the ratio is independent of the intensity of the incident light as well as independent of the angle from which the experiment is imaged and the angle from which the incident light is cast.

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

    DOEpatents

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

    2002-01-01

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

  18. Quantification of esophageal wall thickness in CT using atlas-based segmentation technique

    NASA Astrophysics Data System (ADS)

    Wang, Jiahui; Kang, Min Kyu; Kligerman, Seth; Lu, Wei

    2015-03-01

    Esophageal wall thickness is an important predictor of esophageal cancer response to therapy. In this study, we developed a computerized pipeline for quantification of esophageal wall thickness using computerized tomography (CT). We first segmented the esophagus using a multi-atlas-based segmentation scheme. The esophagus in each atlas CT was manually segmented to create a label map. Using image registration, all of the atlases were aligned to the imaging space of the target CT. The deformation field from the registration was applied to the label maps to warp them to the target space. A weighted majority-voting label fusion was employed to create the segmentation of esophagus. Finally, we excluded the lumen from the esophagus using a threshold of -600 HU and measured the esophageal wall thickness. The developed method was tested on a dataset of 30 CT scans, including 15 esophageal cancer patients and 15 normal controls. The mean Dice similarity coefficient (DSC) and mean absolute distance (MAD) between the segmented esophagus and the reference standard were employed to evaluate the segmentation results. Our method achieved a mean Dice coefficient of 65.55 ± 10.48% and mean MAD of 1.40 ± 1.31 mm for all the cases. The mean esophageal wall thickness of cancer patients and normal controls was 6.35 ± 1.19 mm and 6.03 ± 0.51 mm, respectively. We conclude that the proposed method can perform quantitative analysis of esophageal wall thickness and would be useful for tumor detection and tumor response evaluation of esophageal cancer.

  19. 49 CFR 179.500-4 - Thickness of wall.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specification for Cryogenic Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.500-4 Thickness of wall...

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

    PubMed

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

    2015-06-01

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

  1. The impact of personalized probabilistic wall thickness models on peak wall stress in abdominal aortic aneurysms.

    PubMed

    Biehler, J; Wall, W A

    2018-02-01

    If computational models are ever to be used in high-stakes decision making in clinical practice, the use of personalized models and predictive simulation techniques is a must. This entails rigorous quantification of uncertainties as well as harnessing available patient-specific data to the greatest extent possible. Although researchers are beginning to realize that taking uncertainty in model input parameters into account is a necessity, the predominantly used probabilistic description for these uncertain parameters is based on elementary random variable models. In this work, we set out for a comparison of different probabilistic models for uncertain input parameters using the example of an uncertain wall thickness in finite element models of abdominal aortic aneurysms. We provide the first comparison between a random variable and a random field model for the aortic wall and investigate the impact on the probability distribution of the computed peak wall stress. Moreover, we show that the uncertainty about the prevailing peak wall stress can be reduced if noninvasively available, patient-specific data are harnessed for the construction of the probabilistic wall thickness model. Copyright © 2017 John Wiley & Sons, Ltd.

  2. Comparison of Maximal Wall Thickness in Hypertrophic Cardiomyopathy Differs Between Magnetic Resonance Imaging and Transthoracic Echocardiography.

    PubMed

    Bois, John P; Geske, Jeffrey B; Foley, Thomas A; Ommen, Steve R; Pellikka, Patricia A

    2017-02-15

    Left ventricular (LV) wall thickness is a prognostic marker in hypertrophic cardiomyopathy (HC). LV wall thickness ≥30 mm (massive hypertrophy) is independently associated with sudden cardiac death. Presence of massive hypertrophy is used to guide decision making for cardiac defibrillator implantation. We sought to determine whether measurements of maximal LV wall thickness differ between cardiac magnetic resonance imaging (MRI) and transthoracic echocardiography (TTE). Consecutive patients were studied who had HC without previous septal ablation or myectomy and underwent both cardiac MRI and TTE at a single tertiary referral center. Reported maximal LV wall thickness was compared between the imaging techniques. Patients with ≥1 technique reporting massive hypertrophy received subset analysis. In total, 618 patients were evaluated from January 1, 2003, to December 21, 2012 (mean [SD] age, 53 [15] years; 381 men [62%]). In 75 patients (12%), reported maximal LV wall thickness was identical between MRI and TTE. Median difference in reported maximal LV wall thickness between the techniques was 3 mm (maximum difference, 17 mm). Of the 63 patients with ≥1 technique measuring maximal LV wall thickness ≥30 mm, 44 patients (70%) had discrepant classification regarding massive hypertrophy. MRI identified 52 patients (83%) with massive hypertrophy; TTE, 30 patients (48%). Although guidelines recommend MRI or TTE imaging to assess cardiac anatomy in HC, this study shows discrepancy between the techniques for maximal reported LV wall thickness assessment. In conclusion, because this measure clinically affects prognosis and therapeutic decision making, efforts to resolve these discrepancies are critical. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Gastric full-thickness suturing during EMR and for treatment of gastric-wall defects (with video).

    PubMed

    von Renteln, Daniel; Schmidt, Arthur; Riecken, Bettina; Caca, Karel

    2008-04-01

    The endoscopic full-thickness Plicator device was initially developed to provide an endoscopic treatment option for patients with GERD. Because the endoscopic full-thickness Plicator enables rapid and easy placement of transmural sutures, comparable with surgical sutures, we used the Plicator device for endoscopic treatment or prevention of GI-wall defects. To describe the outcomes and complications of endoscopic full-thickness suturing during EMR and for the treatment of gastric-wall defects. A report of 4 cases treated with the endoscopic full-thickness suturing between June 2006 and April 2007. A large tertiary-referral center. Four subjects received endoscopic full-thickness suturing. The subjects were women, with a mean age of 67 years. Of the 4 subjects, 3 received endoscopic full-thickness suturing during or after an EMR. One subject received endoscopic full-thickness suturing for treatment of a fistula. Primary outcome measurements were clinical procedural success and procedure-related adverse events. The mean time for endoscopic full-thickness suturing was 15 minutes. In all cases, GI-wall patency was restored or ensured, and no procedure-related complications occurred. All subjects responded well to endoscopic full-thickness suturing. The resection of one GI stromal tumor was incomplete. Because of the Plicator's 60F distal-end diameter, endoscopic full-thickness suturing could only be performed with the patient under midazolam and propofol sedation. The durable Plicator suture might compromise the endoscopic follow-up after EMR. The endoscopic full-thickness Plicator permits rapid and easy placement of transmural sutures and seems to be a safe and effective alternative to surgical intervention to restore GI-wall defects or to ensure GI-wall patency during EMR procedures.

  4. Analysis of thermoelastic characteristics in a thick walled FGM cylinder

    NASA Astrophysics Data System (ADS)

    Tanvir, A. N. M.; Islam, Md. Didarul; Ahmed, Faisal

    2017-12-01

    This study is concerned with the behavior of stress and strain in a thick walled functionally graded material (FGM) cylinder under internal pressure. The incompatible eigenstrain and equivalent eigenstrain developed in the cylinder, are taken into account. As a demonstration, a TiC/Al2O3 FGM cylinder is considered and different components of stress and strain are presented in order to study the effects of internal pressure, temperature difference (between room and sintering temperature), cylinder wall thickness and material distribution. The numerical result presented here shows that the thermoelastic characteristic like stress and strain of an FGM cylinder is significantly influenced by some of the above-mentioned parameters and can be controlled by properly controlling these parameters.

  5. Ultrasonic Wall Thickness Monitoring at High Temperatures (>500 °C)

    NASA Astrophysics Data System (ADS)

    Cegla, F. B.; Allin, J.; Davies, J. O.; Collins, P.; Cawley, P.

    2011-06-01

    Corrosion and erosion shorten the life of components that are used in the petrochemical industry. In order to mitigate the safety and financial risks posed by the degradation mechanisms, plant operators monitor wall thicknesses at regular inspection intervals. In high temperature locations inspections have to be carried out at plant shut downs because conventional ultrasonic sensors cannot withstand the high operating temperatures. The authors have developed a waveguide based high temperature thickness gauge for monitoring of wall thicknesses in high temperature areas. The waveguide allows the use of conventional transduction systems (max temp. 60 °C) at one end and guides ultrasonic waves into the high temperature region where the inspection is to be carried out. Slender stainless steel waveguides allow a temperature drop of ˜500-600 °C per 200 mm length to be sustained simply by natural convection cooling. This paper describes the technical challenges that had to be overcome (dispersion and source/receiver characteristics) in order to implement this "acoustic cable". A range of experimental results of thickness measurements on components of different thickness, and furnace tests at different temperatures are presented. An accelerated corrosion test that demonstrates the effectiveness of the monitoring for corrosion is also presented.

  6. Three-dimensional atrial wall thickness maps to inform catheter ablation procedures for atrial fibrillation.

    PubMed

    Bishop, Martin; Rajani, Ronak; Plank, Gernot; Gaddum, Nicholas; Carr-White, Gerry; Wright, Matt; O'Neill, Mark; Niederer, Steven

    2016-03-01

    Transmural lesion formation is critical to success in atrial fibrillation ablation and is dependent on left atrial wall thickness (LAWT). Pre- and peri-procedural planning may benefit from LAWT measurements. To calculate the LAWT, the Laplace equation was solved over a finite element mesh of the left atrium derived from the segmented computed tomographic angiography (CTA) dataset. Local LAWT was then calculated from the length of field lines derived from the Laplace solution that spanned the wall from the endocardium or epicardium. The method was validated on an atrium phantom and retrospectively applied to 10 patients who underwent routine coronary CTA for standard clinical indications at our institute. The Laplace wall thickness algorithm was validated on the left atrium phantom. Wall thickness measurements had errors of <0.2 mm for thicknesses of 0.5-5.0 mm that are attributed to image resolution and segmentation artefacts. Left atrial wall thickness measurements were performed on 10 patients. Successful comprehensive LAWT maps were generated in all patients from the coronary CTA images. Mean LAWT measurements ranged from 0.6 to 1.0 mm and showed significant inter and intra patient variability. Left atrial wall thickness can be measured robustly and efficiently across the whole left atrium using a solution of the Laplace equation over a finite element mesh of the left atrium. Further studies are indicated to determine whether the integration of LAWT maps into pre-existing 3D anatomical mapping systems may provide important anatomical information for guiding radiofrequency ablation. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  7. Sensitivity of dual-wall structures under hypervelocity impact to multi-layer thermal insulation thickness and placement

    NASA Astrophysics Data System (ADS)

    Schonberg, William P.

    1993-04-01

    Results are presented from an experimental study in which Al dual-wall structures were tested, under various high-speed impact conditions, with a view to the effect of multilayer insulation thickness and location on perforation resistance. Attention is given to comparisons of the damage sustained by dual-wall systems with multilayer insulation blankets of various thicknesses and at various locations within the dual-wall system, under comparable impact loading conditions. The placement of the insulation has a significant effect on the ballistic limit of the dual-wall structures considered, while reducing insulation thickness by as much as a third did not.

  8. [The cutaneous groin flap for coverage of a full-thickness abdominal wall defect].

    PubMed

    Doebler, O; Spierer, R

    2010-08-01

    A full-thickness defect of the abdominal wall is rare and may occur as a complication of extended abdominal surgery procedures. We report about a 69-year-old patient who was presented to our department with a full-thickness abdominal wall defect and a fully exposed collagen-mesh for reconstructive wound closure. 13 operations with resections of necrotic parts of the abdominal wall were performed following a complicated intraabdominal infection. After debridement and mesh explantation, closure of the remaining defect of the lower abdominal region was achieved by a cutaneous groin flap. Georg Thieme Verlag KG Stuttgart New York.

  9. Dietary fat intake and carotid artery wall thickness: the Atherosclerosis Risk in Communities (ARIC) Study.

    PubMed

    Tell, G S; Evans, G W; Folsom, A R; Shimakawa, T; Carpenter, M A; Heiss, G

    1994-05-15

    Associations between atherosclerosis and dietary fat and cholesterol have been demonstrated in numerous animal experiments. The relation between these dietary components and atherosclerosis has not previously been reported in a population-based study among human beings. The associations of dietary fat and cholesterol with carotid artery wall thickness (atherosclerosis) were investigated in a population-based study, the Atherosclerosis Risk in Communities (ARIC) Study, from 1987 to 1989. Participants were 2,095 black women, 5,146 white women, 1,318 black men and 4,589 white men, aged 45-64 years, recruited from four US communities: Jackson, Mississippi; Forsyth County, North Carolina; Washington County, Maryland; and Minneapolis, Minnesota. Habitual diet was assessed with a food frequency questionnaire. Wall thickness was measured with B-mode ultrasound. After adjustment for age and energy intake, animal fat, saturated fat, monounsaturated fat, cholesterol, and Keys' score were positively related to wall thickness, while vegetable fat and polyunsaturated fat were inversely related to wall thickness. These associations persisted after further adjustment for smoking and hypertension and were consistent across the four race and sex groups. Thus, elements of habitual dietary intake were consistently associated with carotid artery wall thickness, compatible with their putatively atherogenic and antiatherogenic properties.

  10. Forming limit diagrams of tubes with initial wall-thickness difference based on different instability criteria

    NASA Astrophysics Data System (ADS)

    Zhao, Qiwen; Yang, Lianfa; He, Yulin

    2018-05-01

    The Forming limit diagram (FLD), also known as a forming limit curves (FLC), is generally used in metal forming for predicting forming behavior of metals. The purpose of the study is to clarify the difference among the FLC of tubes with initial wall-thickness difference under tension-compression strain states using finite element (FE) simulation of tube hydroforming (THF) and different instability criteria. Firstly, geometrical models for SUS304 stainless steel tubes with initial wall-thickness differences were built by introducing an index `wall-thickness deviation rate'. Secondly, forced-end hydro-bugling of the tubes was modeled and the forming process was simulated by using the commercial finite element (FE) code ABAQUS/Explicit 6.10. Afterwards, the limiting strains of the material in the hydro-bugling process were calculated based on the simulated resultant data and three instability criteria-strain change criterion, strain rate change criterion and strain path change criterion, respectively. Finally, the FLD for the tubes was established and the effect of wall-thickness deviation rate on the FLD was analyzed and the differences among the FLC based on the three instability criteria were compared. The results showed that the FLC are observed to shift in the major-minor strain coordinate system due to the initial non-uniform wall-thickness; however, no distinct differences among the FLC based on the three instability criteria were observed.

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

    NASA Technical Reports Server (NTRS)

    Goetz, Guenter; Noetzold, Dirk

    1989-01-01

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

  12. The implications of different lateral wall thicknesses on surgical access to the maxillary sinus.

    PubMed

    Lim, Ee Lian; Ngeow, Wei Cheong; Lim, Daniel

    2017-11-27

    The objective of this study was to measure the topographic thickness of the lateral wall of the maxillary sinus in selected Asian populations. Measurements were made on the lateral walls of maxillary sinuses recorded using CBCT in a convenient sample of patients attending an Asian teaching hospital. The points of measurement were the intersections between the axes along the apices of the canine, first premolar, and second premolar and along the mesiobuccal and distobuccal apices of the first and second molars and horizontal planes 10 mm, 20 mm, 30 mm and 40 mm beneath the orbital floor. The CBCT images of 109 patients were reviewed. The mean age of the patients was 33.0 (SD 14.8) years. Almost three quarters (71.8%) of the patients were male. The mean bone thickness decreased beginning at the 10-mm level and continuing to 40 mm below the orbital floor. Few canine regions showed encroachment of the maxillary sinus. The thickness of the buccal wall gradually increased from the canine region (where sinus encroachment of the canine region was present) to the first molar region, after which it decreased to the thickness observed at the canine region. The buccal wall of the maxillary sinus became thicker anteroposteriorly, except in the region of the second molar, and thinner superoinferiorly. These changes will affect the approach used to osteotomize the lateral sinus wall for oral surgery and for the sinus lift procedure.

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

    NASA Astrophysics Data System (ADS)

    Tang, Jiang; Hasegawa, Hideyuki; Kanai, Hiroshi

    2005-06-01

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

  14. Inverse Transient Analysis for Classification of Wall Thickness Variations in Pipelines

    PubMed Central

    Tuck, Jeffrey; Lee, Pedro

    2013-01-01

    Analysis of transient fluid pressure signals has been investigated as an alternative method of fault detection in pipeline systems and has shown promise in both laboratory and field trials. The advantage of the method is that it can potentially provide a fast and cost effective means of locating faults such as leaks, blockages and pipeline wall degradation within a pipeline while the system remains fully operational. The only requirement is that high speed pressure sensors are placed in contact with the fluid. Further development of the method requires detailed numerical models and enhanced understanding of transient flow within a pipeline where variations in pipeline condition and geometry occur. One such variation commonly encountered is the degradation or thinning of pipe walls, which can increase the susceptible of a pipeline to leak development. This paper aims to improve transient-based fault detection methods by investigating how changes in pipe wall thickness will affect the transient behaviour of a system; this is done through the analysis of laboratory experiments. The laboratory experiments are carried out on a stainless steel pipeline of constant outside diameter, into which a pipe section of variable wall thickness is inserted. In order to detect the location and severity of these changes in wall conditions within the laboratory system an inverse transient analysis procedure is employed which considers independent variations in wavespeed and diameter. Inverse transient analyses are carried out using a genetic algorithm optimisation routine to match the response from a one-dimensional method of characteristics transient model to the experimental time domain pressure responses. The accuracy of the detection technique is evaluated and benefits associated with various simplifying assumptions and simulation run times are investigated. It is found that for the case investigated, changes in the wavespeed and nominal diameter of the pipeline are both important

  15. Fine-tuning the Wall Thickness of Ordered Mesoporous Graphene by Exploiting Ligand Exchange of Colloidal Nanocrystals

    NASA Astrophysics Data System (ADS)

    Han, Dandan; Yan, Yancui; Wei, Jishi; Wang, Biwei; Li, Tongtao; Guo, Guannan; Yang, Dong; Xie, Songhai; Dong, Angang

    2017-12-01

    Because of their unique physical properties, three-dimensional (3D) graphene has attracted enormous attention over the past years. However, it is still a challenge to precisely control the layer thickness of 3D graphene. Here, we report a novel strategy to rationally adjust the wall thickness of ordered mesoporous graphene (OMG). By taking advantage of ligand exchange capability of colloidal Fe3O4 nanocrystals, we are able to fine-tune the wall thickness of OMG from 2 to 6 layers of graphene by tailoring the hydrocarbon ligands attached to the nanocrystal surface. When evaluated as electrocatalyst for oxygen reduction reaction upon S and N doping, the 4-layer OMG is found to show better catalytic performance compared with its 2- and 6-layer counterparts, which we attribute to the enhanced exposure of active sites resulting from its ultrathin wall thickness and high surface area.

  16. Composite laminates with negative through-the-thickness Poisson's ratios

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.

    1984-01-01

    A simple analysis using two dimensional lamination theory combined with the appropriate three dimensional anisotropic constitutive equation is presented to show some rather surprising results for the range of values of the through-the-thickness effective Poisson's ratio nu sub xz for angle ply laminates. Results for graphite-epoxy show that the through-the-thickness effective Poisson's ratio can range from a high of 0.49 for a 90 laminate to a low of -0.21 for a + or - 25s laminate. It is shown that negative values of nu sub xz are also possible for other laminates.

  17. Composite laminates with negative through-the-thickness Poisson's ratios

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.

    1984-01-01

    A simple analysis using two-dimensional lamination theory combined with the appropriate three-dimensional anisotropic constitutive equation is presented to show some rather surprising results for the range of values of the through-the-thickness effective Poisson's ratio nu sub xz for angle ply laminates. Results for graphite-epoxy show that the through-the-thickness effective Poisson's ratio can range from a high of 0.49 for a 90 laminate to a low of -0.21 for a + or - 25s laminate. It is shown that negative values of nu sub xz are also possible for other laminates.

  18. Echocardiographic Manifestations of Glycogen Storage Disease III: Increase in Wall Thickness and Left Ventricular Mass over Time

    PubMed Central

    Vertilus, Shawyntee M.; Austin, Stephanie L.; Foster, Kimberly S.; Boyette, Keri E.; Bali, Deeksha; Li, Jennifer S.; Kishnani, Priya S.; Wechsler, Stephanie Burns

    2013-01-01

    Purpose Glycogen Storage Disease (GSD) type III, glycogen debranching enzyme deficiency, causes accumulation of glycogen in liver, skeletal, and cardiac muscle. Some patients develop increased left ventricular (LV) thickness by echocardiography, but the rate of increase and its significance remain unclear. Methods We evaluated 33 patients with GSD type III, 23 with IIIa and 10 with IIIb, ages 1 month – 55.5 yrs, by echocardiography for wall thickness, LV mass, shortening and ejection fractions, at 1 time point (n = 33) and at 2 time points in patients with more than 1 echocardiogram (13 of the 33). Results Of 23 cross-sectional patients with type IIIa, 12 had elevated LV mass, 11 had elevated wall thickness. One type IIIb patient had elevated LV mass but 4 had elevated wall thickness. For those with multiple observations, 9 of 10 with type IIIa developed increased LV mass over time, with 3 already increased at first measurement. Shortening and ejection fractions were generally normal. Conclusion Elevated LV mass and wall thickness is more common in patients with type IIIa but develops rarely in type IIIb, though ventricular systolic function is preserved. This suggests serial echocardiograms with attention to LV thickness and mass are important for care of these patients. PMID:20526204

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  20. SU-C-BRA-04: Use of Esophageal Wall Thickness in Evaluation of the Response to Chemoradiation Therapy for Esophageal Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, J; Kligerman, S; Lu, W

    2015-06-15

    Purpose: To quantitatively evaluate the esophageal cancer response to chemoradiation therapy (CRT) by measuring the esophageal wall thickness in CT. Method: Two datasets were used in this study. The first dataset is composed of CT scans of 15 esophageal cancer patients and 15 normal controls. The second dataset is composed of 20 esophageal cancer patients who underwent PET/CT scans before (Pre-CRT) and after CRT (Post-CRT). We first segmented the esophagus using a multi-atlas-based algorithm. The esophageal wall thickness was then computed, on each slice, as the equivalent circle radius of the segmented esophagus excluding the lumen. To evaluate the changesmore » of wall thickness, we computed the standard deviation (SD), coefficient of variation (COV, SD/Mean), and flatness [(Max–Min)/Mean] of wall thickness along the entire esophagus. Results: For the first dataset, the mean wall thickness of cancer patients and normal controls were 6.35 mm and 6.03 mm, respectively. The mean SD, COV, and flatness of the wall thickness were 2.59, 0.21, and 1.27 for the cancer patients and 1.99, 0.16, and 1.13 for normal controls. Statistically significant differences (p < 0.05) were identified in SD and flatness. For the second dataset, the mean wall thickness of pre-CRT and post-CRT patients was 7.13 mm and 6.84 mm, respectively. The mean SD, COV, and flatness were 1.81, 0.26, and 1.06 for pre-CRT and 1.69, 0.26, and 1.06 for post-CRT. Statistically significant difference was not identified for these measurements. Current results are based on the entire esophagus. We believe significant differences between pre- and post-CRT scans could be obtained, if we conduct the measurements at tumor sites. Conclusion: Results show thicker wall thickness in pre-CRT scans and differences in wall thickness changes between normal and abnormal esophagus. This demonstrated the potential of esophageal wall thickness as a marker in the tumor CRT response evaluation. This work was supported in

  1. Quantification of common carotid artery and descending aorta vessel wall thickness from MR vessel wall imaging using a fully automated processing pipeline.

    PubMed

    Gao, Shan; van 't Klooster, Ronald; Brandts, Anne; Roes, Stijntje D; Alizadeh Dehnavi, Reza; de Roos, Albert; Westenberg, Jos J M; van der Geest, Rob J

    2017-01-01

    To develop and evaluate a method that can fully automatically identify the vessel wall boundaries and quantify the wall thickness for both common carotid artery (CCA) and descending aorta (DAO) from axial magnetic resonance (MR) images. 3T MRI data acquired with T 1 -weighted gradient-echo black-blood imaging sequence from carotid (39 subjects) and aorta (39 subjects) were used to develop and test the algorithm. The vessel wall segmentation was achieved by respectively fitting a 3D cylindrical B-spline surface to the boundaries of lumen and outer wall. The tube-fitting was based on the edge detection performed on the signal intensity (SI) profile along the surface normal. To achieve a fully automated process, Hough Transform (HT) was developed to estimate the lumen centerline and radii for the target vessel. Using the outputs of HT, a tube model for lumen segmentation was initialized and deformed to fit the image data. Finally, lumen segmentation was dilated to initiate the adaptation procedure of outer wall tube. The algorithm was validated by determining: 1) its performance against manual tracing; 2) its interscan reproducibility in quantifying vessel wall thickness (VWT); 3) its capability of detecting VWT difference in hypertensive patients compared with healthy controls. Statistical analysis including Bland-Altman analysis, t-test, and sample size calculation were performed for the purpose of algorithm evaluation. The mean distance between the manual and automatically detected lumen/outer wall contours was 0.00 ± 0.23/0.09 ± 0.21 mm for CCA and 0.12 ± 0.24/0.14 ± 0.35 mm for DAO. No significant difference was observed between the interscan VWT assessment using automated segmentation for both CCA (P = 0.19) and DAO (P = 0.94). Both manual and automated segmentation detected significantly higher carotid (P = 0.016 and P = 0.005) and aortic (P < 0.001 and P = 0.021) wall thickness in the hypertensive patients. A reliable and reproducible pipeline for fully

  2. Optimum Material Composition for Minimizing the Stress Intensity Factor of Edge Crack in Thick-Walled FGM Circular Pipes Under Thermomechanical Loading

    NASA Astrophysics Data System (ADS)

    Sekine, Hideki; Yoshida, Kimiaki

    This paper deals with the optimization problem of material composition for minimizing the stress intensity factor of radial edge crack in thick-walled functionally graded material (FGM) circular pipes under steady-state thermomechanical loading. Homogenizing the FGM circular pipes by simulating the inhomogeneity of thermal conductivity by a distribution of equivalent eigentemperature gradient and the inhomogeneity of Young's modulus and Poisson's ratio by a distribution of equivalent eigenstrain, we present an approximation method to obtain the stress intensity factor of radial edge crack in the FGM circular pipes. The optimum material composition for minimizing the stress intensity factor of radial edge crack is determined using a nonlinear mathematical programming method. Numerical results obtained for a thick-walled TiC/Al2O3 FGM circular pipe reveal that it is possible to decrease remarkably the stress intensity factor of radial edge crack by setting the optimum material composition profile.

  3. Impact of emphysema and airway wall thickness on quality of life in smoking-related COPD.

    PubMed

    Gietema, Hester A; Edwards, Lisa D; Coxson, Harvey O; Bakke, Per S

    2013-08-01

    Limited data are available as to the relationship between computed tomography (CT) derived data on emphysema and airway wall thickness, and quality of life in subjects with chronic obstructive pulmonary disease (COPD). Such data may work to clarify the clinical correlate of the CT findings. We included 1778 COPD subjects aged 40-75 years with a smoking history of at least 10 pack-years. They were examined with St George's Respiratory Questionnaire (SGRQ-C) and high-resolution chest CT. Level of emphysema was assessed as percent low-attenuation areas less than -950 Hounsfield units (%LAA). Airway wall thickness was estimated by calculating the square root of wall area of an imaginary airway with an internal perimeter of 10 mm (Pi10). In both men and women, the mean total score and most of the subscores of SGRQ-C increased with increasing level of emphysema and increasing level of airway wall thickness, after adjusting for age, smoking status, pack years, body mass index and FEV1. The highest gradient was seen in the relationship between the activity score and the emphysema level. The activity score increased by 35% from the lowest to the highest emphysema tertile. The relationship between level of emphysema and the total SGRQ-C score became weaker with increasing GOLD (Global initiative for Chronic Obstructive Lung Disease) stages (p < 0.001), while the impact of gender was limited. In subjects with COPD, increasing levels of emphysema and airway wall thickness are independently related to impaired quality of life. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Suprascarpal fat pad thickness may predict venous drainage patterns in abdominal wall flaps.

    PubMed

    Bast, John; Pitcher, Austin A; Small, Kevin; Otterburn, David M

    2016-02-01

    Abdominal wall flaps are routinely used in reconstructive procedures. In some patients inadequate venous drainage from the deep vein may cause fat necrosis or flap failure. Occasionally the superficial inferior epigastric vessels (SIEV) are of sufficient size to allow for microvascular revascularization. This study looked at the ratio of the sub- and suprascarpal fat layers, the number of deep system perforators, and SIEV diameter to determine any correlation of the fat topography and SIEV. 50 abdominal/pelvic CT angiograms (100 hemiabdomens) were examined in women aged 34-70 years for number of perforators, SIEV diameter, and fat pad thickness above and below Scarpa's fascia. Data was analyzed using multivariate model. The average suprascarpal and subscarpal layers were 18.6 ± 11.5 mm and 6.2 ± 7.2 mm thick, respectively. The average SIEV diameter was 2.06 ± 0.81 mm and the average number of perforators was 2.09 ± 1.03 per hemiabdomen. Hemiabdomens with suprascarpal thickness>23 mm had greater SIEV diameter [2.69 mm vs. 1.8 mm (P < 0.0001)] The fat layer thickness did not correlate with the number of perforators. Neither subscarpal fat thickness nor suprascarpal-to-subscarpal fat layer thickness correlated significantly with SIEV caliber or number of perforators in multivariate model. Suprascarpal fat pad thicker than 23 mm had larger SIEVs irrespective of the number of deep system perforators. This may indicate a cohort of patients at risk of venous congestion from poor venous drainage if only the deep system is revascularized. We recommend harvesting the SIEV in patients with suprascarpal fat pad >23 mm to aid in superficial drainage. © 2015 Wiley Periodicals, Inc.

  5. Critical thickness ratio for buckled and wrinkled fruits and vegetables

    NASA Astrophysics Data System (ADS)

    Dai, Hui-Hui; Liu, Yang

    2014-11-01

    This work aims at establishing the geometrical constraint for buckled and wrinkled shapes by modeling a fruit/vegetable with exocarp and sarcocarp as a hyperelastic layer-substrate structure subjected to uniaxial compression. A careful analysis on the derived bifurcation condition leads to the finding of a critical thickness ratio which separates the buckling and wrinkling modes, and remarkably, which is independent of the material stiffnesses. More specifically, it is found that if the thickness ratio is smaller than this critical value a fruit/vegetable should be in a buckled shape (under a sufficient stress); if a fruit/vegetable is in a wrinkled shape the thickness ratio is always larger than this critical value. To verify the theoretical prediction, we consider four types of buckled fruits/vegetables and four types of wrinkled fruits/vegetables with three samples in each type. The geometrical parameters for the 24 samples are measured and it is found that indeed all the data fall into the theoretically predicted buckling or wrinkling domains.

  6. Optimization of Surface Roughness and Wall Thickness in Dieless Incremental Forming Of Aluminum Sheet Using Taguchi

    NASA Astrophysics Data System (ADS)

    Hamedon, Zamzuri; Kuang, Shea Cheng; Jaafar, Hasnulhadi; Azhari, Azmir

    2018-03-01

    Incremental sheet forming is a versatile sheet metal forming process where a sheet metal is formed into its final shape by a series of localized deformation without a specialised die. However, it still has many shortcomings that need to be overcome such as geometric accuracy, surface roughness, formability, forming speed, and so on. This project focus on minimising the surface roughness of aluminium sheet and improving its thickness uniformity in incremental sheet forming via optimisation of wall angle, feed rate, and step size. Besides, the effect of wall angle, feed rate, and step size to the surface roughness and thickness uniformity of aluminium sheet was investigated in this project. From the results, it was observed that surface roughness and thickness uniformity were inversely varied due to the formation of surface waviness. Increase in feed rate and decrease in step size will produce a lower surface roughness, while uniform thickness reduction was obtained by reducing the wall angle and step size. By using Taguchi analysis, the optimum parameters for minimum surface roughness and uniform thickness reduction of aluminium sheet were determined. The finding of this project helps to reduce the time in optimising the surface roughness and thickness uniformity in incremental sheet forming.

  7. Multimodal optical measurement in vitro of surface deformations and wall thickness of the pressurized aortic arch

    NASA Astrophysics Data System (ADS)

    Genovese, Katia; Humphrey, Jay D.

    2015-04-01

    Computational modeling of arterial mechanics continues to progress, even to the point of allowing the study of complex regions such as the aortic arch. Nevertheless, most prior studies assign homogeneous and isotropic material properties and constant wall thickness even when implementing patient-specific luminal geometries obtained from medical imaging. These assumptions are not due to computational limitations, but rather to the lack of spatially dense sets of experimental data that describe regional variations in mechanical properties and wall thickness in such complex arterial regions. In this work, we addressed technical challenges associated with in vitro measurement of overall geometry, full-field surface deformations, and regional wall thickness of the porcine aortic arch in its native anatomical configuration. Specifically, we combined two digital image correlation-based approaches, standard and panoramic, to track surface geometry and finite deformations during pressurization, with a 360-deg fringe projection system to contour the outer and inner geometry. The latter provided, for the first time, information on heterogeneous distributions of wall thickness of the arch and associated branches in the unloaded state. Results showed that mechanical responses vary significantly with orientation and location (e.g., less extensible in the circumferential direction and with increasing distance from the heart) and that the arch exhibits a nearly linear increase in pressure-induced strain up to 40%, consistent with other findings on proximal porcine aortas. Thickness measurements revealed strong regional differences, thus emphasizing the need to include nonuniform thicknesses in theoretical and computational studies of complex arterial geometries.

  8. The Effects of Modified Wall Squat Exercises on Average Adults’ Deep Abdominal Muscle Thickness and Lumbar Stability

    PubMed Central

    Cho, Misuk

    2013-01-01

    [Purpose] The purpose of this study was to compare the effects of bridge exercises applying the abdominal drawing-in method and modified wall squat exercises on deep abdominal muscle thickness and lumbar stability. [Subjects] A total of 30 subjects were equally divided into an experimental group and a control group. [Methods] The experimental group completed modified wall squat exercises, and the control group performed bridge exercises. Both did so for 30 minutes three times per week over a six-week period. Both groups’ transversus abdominis (Tra), internal oblique (IO), and multifidus muscle thickness were measured using ultrasonography, while their static lumbar stability and dynamic lumbar stability were measured using a pressure biofeedback unit. [Results] A comparison of the pre-intervention and post-intervention measures of the experimental group and the control group was made; the Tra and IO thicknesses were significantly different in both groups. [Conclusion] The modified wall squat exercise and bridge exercise affected the thicknesses of the Tra and the IO muscles. While the bridge exercise requirs space and a mattress to lie on, the modified wall squat exercise can be conveniently performed anytime. PMID:24259831

  9. Effect of the Coronal Wall Thickness of Dental Implants on the Screw Joint Stability in the Internal Implant-Abutment Connection.

    PubMed

    Lee, Ji-Hye; Huh, Yoon-Hyuk; Park, Chan-Jin; Cho, Lee-Ra

    2016-01-01

    To evaluate the effect of implant coronal wall thickness on load-bearing capacity and screw joint stability. Experimental implants were customized after investigation of the thinnest coronal wall thickness of commercially available implant systems with a regular platform diameter. Implants with four coronal wall thicknesses (0.2, 0.3, 0.4, and 0.5 mm) were fabricated. Three sets of tests were performed. The first set was a failure test to evaluate load-bearing capacity and elastic limit. The second and third sets were cyclic and static loading tests. After abutment screw tightening of each implant, vertical cyclic loading of 250 N or static loading from 250 to 800 N was applied. Coronal diameter expansion, axial displacement, and removal torque values of the implants were compared. Repeated measures analysis of variance (ANOVA) was used for statistical analysis (α = .05). Implants with 0.2-mm coronal wall thickness demonstrated significantly low load-bearing capacity and elastic limit (both P < .05). These implants also showed significantly large coronal diameter expansion and axial displacement after screw tightening (both P < .05). Greater vertical load and thinner coronal wall thickness significantly increased coronal diameter expansion of the implant, axial displacement of the abutment, and removal torque loss of the abutment screw (all P < .05). Implant coronal wall thickness of 0.2 mm produces significantly inferior load-bearing capacity and screw joint stability.

  10. Effect of multi-layer thermal insulation thickness and location on the hypervelocity impact response of dual-wall structures

    NASA Astrophysics Data System (ADS)

    Schonberg, William P.

    Traditional perforation-resistant wall design for long-duration spacecraft consists of a "bumper" that is placed a small distance away from the main "pressure wall" of a spacecraft compartment or module. This concept has been studied extensively as a means of reducing the perforation threat of hypervelocity projectiles such as meteoroids and orbital debris. If a dual-wall system is employed on an earth-orbiting spacecraft, then a blanket of multi-layer insulation (MLI) will typically be included within the dual-wall system for thermal protection purposes. This paper presents the results of an experimental study in which aluminum dual-wall structures were tested under a variety of high-speed impact conditions to study the effect of MLI thickness and location on perforation resistance. The results presented consist of test-by-test comparisons of the damage sustained by similar dual-wall systems with blanket MLI of various thicknesses and at various locations within the dual-wall systems under similar impact loading conditions. The analyses performed revealed that the placement of the MLI had a significant effect on the ballistic limit of the dual-wall structures considered while reducing the thickness of the MLI by as much as 1/3 did not.

  11. The development and structure of thick-walled, multicellular, aerial spores in Diheterospora chlamydosporia (=Verticillium chlamydosporium).

    PubMed

    Cambell, W P; Griffiths, D A

    1975-07-01

    The aerial, thick-walled spores in Diheterospara chlamydosporia arose as terminal swellings on erect hyphae. Repeated septation of the continuously swelling spore resulted in a multicellular structure. Immediately after the onset of septation secondary wall material was laid down between the two-layered primary wall and the plasmalemma. The presence of secondary wall material indicates that the multicellular spore is a dictyochlamydospore and not an aleuriospore. The relationship between chlamydospores and aleuriospores in other fungi is discussed.

  12. Comparative physical and chemical analyses of cotton fibers from two near isogenic upland lines differing in fiber wall thickness

    USDA-ARS?s Scientific Manuscript database

    The thickness of cotton fiber cell walls is an important property that partially determines the economic value of cotton. To better understand the physical and chemical manifestations of the genetic variations that regulate the degree of fiber wall thickness, we used a comprehensive set of methods t...

  13. Photoelastic Analysis of Cracked Thick Walled Cylinders

    NASA Astrophysics Data System (ADS)

    Pastramă, Ştefan Dan

    2017-12-01

    In this paper, the experimental determination of the stress intensity factor in thick walled cylinders subject to uniform internal pressure and having longitudinal non-penetrating cracks is presented. Photoelastic measurements were used together with the expressions of the stress field near the crack tip for Mode I crack extension and a specific methodology for stress intensity factor determination. Two types of longitudinal cracks - internal and external - were considered. Four plane models were manufactured and analyzed in a plane polariscope at different values of the applied internal pressure. The values of the normalized stress intensity factor were calculated and the results were compared to those reported by other authors. A good accuracy was noticed, showing the reliability of the experimental procedure.

  14. Effect of length to thickness ratio on free vibration analysis of thick fiber reinforced plastic skew cross-ply laminate with circular cutout

    NASA Astrophysics Data System (ADS)

    Srividya, K.; Reddy, Ch. Kishore; Sumanth, Ch. Mohan; Krishnaiah, P. Gopala; Kishan, V. Mallikharjuna

    2018-04-01

    The present investigation deals with the free vibration analysis of a thick four-layered symmetric cross-ply skew laminated composite plate with a circular cutout. Three dimensional finite element models (FEM) which use the elasticity theory for the determination of stiffness matrices are modeled in ANSYS software to evaluate first five natural frequencies of the laminate. The variations of the first five natural frequencies with respect to length to thickness ratio (S) for different diameter to length ratios (d/l) are presented. It is observed that, the natural frequencies decreases with increase of thickness ratio(S).

  15. Development of a Flexible Broadband Rayleigh Waves Comb Transducer with Nonequidistant Comb Interval for Defect Detection of Thick-Walled Pipelines

    PubMed Central

    He, Cunfu; Yan, Lyu; Zhang, Haijun

    2018-01-01

    It is necessary to develop a transducer that can quickly detect the inner and outer wall defects of thick-walled pipes, in order to ensure the safety of such pipes. In this paper, a flexible broadband Rayleigh-waves comb transducer based on PZT (lead zirconate titanate) for defect detection of thick-walled pipes is studied. The multiple resonant coupling theory is used to expand the transducer broadband and the FEA (Finite Element Analysis) method is used to optimize transducer array element parameters. Optimization results show that the best array element parameters of the transducer are when the transducer array element length is 30 mm, the thickness is 1.2 mm, the width of one end of is 1.5 mm, and the other end is 3 mm. Based on the optimization results, such a transducer was fabricated and its performance was tested. The test results were consistent with the finite-element simulation results, and the −3 dB bandwidth of the transducer reached 417 kHz. Transducer directivity test results show that the Θ−3dB beam width was equal to 10 °, to meet the defect detection requirements. Finally, defects of thick-walled pipes were detected using the transducer. The results showed that the transducer could detect the inner and outer wall defects of thick-walled pipes within the bandwidth. PMID:29498636

  16. Development of a Flexible Broadband Rayleigh Waves Comb Transducer with Nonequidistant Comb Interval for Defect Detection of Thick-Walled Pipelines.

    PubMed

    Zhao, Huamin; He, Cunfu; Yan, Lyu; Zhang, Haijun

    2018-03-02

    It is necessary to develop a transducer that can quickly detect the inner and outer wall defects of thick-walled pipes, in order to ensure the safety of such pipes. In this paper, a flexible broadband Rayleigh-waves comb transducer based on PZT (lead zirconate titanate) for defect detection of thick-walled pipes is studied. The multiple resonant coupling theory is used to expand the transducer broadband and the FEA (Finite Element Analysis) method is used to optimize transducer array element parameters. Optimization results show that the best array element parameters of the transducer are when the transducer array element length is 30 mm, the thickness is 1.2 mm, the width of one end of is 1.5 mm, and the other end is 3 mm. Based on the optimization results, such a transducer was fabricated and its performance was tested. The test results were consistent with the finite-element simulation results, and the -3 dB bandwidth of the transducer reached 417 kHz. Transducer directivity test results show that the Θ -3dB beam width was equal to 10 °, to meet the defect detection requirements. Finally, defects of thick-walled pipes were detected using the transducer. The results showed that the transducer could detect the inner and outer wall defects of thick-walled pipes within the bandwidth.

  17. Effect of Thickness-to-Chord Ratio on Flow Structure of Low Swept Delta Wing

    NASA Astrophysics Data System (ADS)

    Gulsacan, Burak; Sencan, Gizem; Yavuz, Mehmet Metin

    2017-11-01

    The effect of thickness-to-chord (t/C) ratio on flow structure of a delta wing with sweep angle of 35 degree is characterized in a low speed wind tunnel using laser illuminated smoke visualization, particle image velocimetry, and surface pressure measurements. Four different t/C ratio varying from 4.75% to 19% are tested at angles of attack 4, 6, 8, and 10 degrees for Reynolds numbers Re =10,000 and 35,000. The results indicate that the effect of thickness-to-chord ratio on flow structure is quite substantial, such that, as the wing thickness increases, the flow structure transforms from leading edge vortex to three-dimensional separated flow regime. The wing with low t/C ratio of 4.75% experiences pronounced surface separation at significantly higher angle of attack compared to the wing with high t/C ratio. The results might explain some of the discrepancies reported in previously conducted studies related to delta wings. In addition, it is observed that the thickness of the shear layer separated from windward side of the wing is directly correlated with the thickness of the wing. To conclude, the flow structure on low swept delta wing is highly affected by t/C ratio, which in turn might indicate the potential usage of wing thickness as an effective flow control parameter.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  19. Relationship between Pipeline Wall Thickness (Gr. X60) and Water Depth towards Avoiding Failure during Installation

    NASA Astrophysics Data System (ADS)

    Razak, K. Abdul; Othman, M. I. H.; Mat Yusuf, S.; Fuad, M. F. I. Ahmad; yahaya, Effah

    2018-05-01

    Oil and gas today being developed at different water depth characterized as shallow, deep and ultra-deep waters. Among the major components involved during the offshore installation is pipelines. Pipelines are a transportation method of material through a pipe. In oil and gas industry, pipeline come from a bunch of line pipe that welded together to become a long pipeline and can be divided into two which is gas pipeline and oil pipeline. In order to perform pipeline installation, we need pipe laying barge or pipe laying vessel. However, pipe laying vessel can be divided into two types: S-lay vessel and J-lay vessel. The function of pipe lay vessel is not only to perform pipeline installation. It also performed installation of umbilical or electrical cables. In the simple words, pipe lay vessel is performing the installation of subsea in all the connecting infrastructures. Besides that, the installation processes of pipelines require special focus to make the installation succeed. For instance, the heavy pipelines may exceed the lay vessel’s tension capacities in certain kind of water depth. Pipeline have their own characteristic and we can group it or differentiate it by certain parameters such as grade of material, type of material, size of diameter, size of wall thickness and the strength. For instances, wall thickness parameter studies indicate that if use the higher steel grade of the pipelines will have a significant contribution in pipeline wall thickness reduction. When running the process of pipe lay, water depth is the most critical thing that we need to monitor and concern about because of course we cannot control the water depth but we can control the characteristic of the pipe like apply line pipe that have wall thickness suitable with current water depth in order to avoid failure during the installation. This research will analyse whether the pipeline parameter meet the requirements limit and minimum yield stress. It will overlook to simulate pipe

  20. Method of controlling the side wall thickness of a turbine nozzle segment for improved cooling

    DOEpatents

    Burdgick, Steven Sebastian

    2002-01-01

    A gas turbine nozzle segment has outer and inner bands and a vane extending therebetween. Each band has a side wall, a cover and an impingement plate between the cover and nozzle wall defining two cavities on opposite sides of the impingement plate. Cooling steam is supplied to one cavity for flow through apertures of the impingement plate to cool the nozzle wall. The side wall of the band has an inturned flange defining with the nozzle wall an undercut region. The outer surface of the side wall is provided with a step prior to welding the cover to the side wall. A thermal barrier coating is applied in the step and, after the cover is welded to the side wall, the side wall is finally machined to a controlled thickness removing all, some or none of the coating.

  1. Dynamic film thickness between bubbles and wall in a narrow channel

    NASA Astrophysics Data System (ADS)

    Ito, Daisuke; Damsohn, Manuel; Prasser, Horst-Michael; Aritomi, Masanori

    2011-09-01

    The present paper describes a novel technique to characterize the behavior of the liquid film between gas bubbles and the wall in a narrow channel. The method is based on the electrical conductance. Two liquid film sensors are installed on both opposite walls in a narrow rectangular channel. The liquid film thickness underneath the gas bubbles is recorded by the first sensor, while the void fraction information is obtained by measuring the conductance between the pair of opposite sensors. Both measurements are taken on a large two-dimensional domain and with a high speed. This makes it possible to obtain the two-dimensional distribution of the dynamic liquid film between the bubbles and the wall. In this study, this method was applied to an air-water flow ranging from bubbly to churn regimes in the narrow channel with a gap width of 1.5 mm.

  2. New research perspectives from a novel approach to quantify tracheid wall thickness.

    PubMed

    Prendin, Angela Luisa; Petit, Giai; Carrer, Marco; Fonti, Patrick; Björklund, Jesper; von Arx, Georg

    2017-07-01

    The analysis of xylem cell anatomical features in dated tree rings provides insights into xylem functional responses and past growth conditions at intra-annual resolution. So far, special focus has been given to the lumen of the water-conducting cells, whereas the equally relevant cell wall thickness (CWT) has been less investigated due to methodological limitations. Here we present a novel approach to measure tracheid CWT in high-resolution images of wood cross-sections that is implemented within the specialized image-analysis tool 'ROXAS'. Compared with the traditional manual line measurements along a selection of few radial files, this novel image-analysis tool can: (i) measure CWT of all tracheids in a tree-ring cross-section, thus increasing the number of individual tracheid measurements by a factor of ~10-20; (ii) measure the tangential and radial walls separately; and (iii) laterally integrate the measurements in a customizable way from only the thinnest central part of the cell walls up to the thickest part of the tracheids at the corners. Cell wall thickness measurements performed with our novel approach and the traditional manual approach showed comparable accuracy for several image resolutions, with an optimal accuracy-efficiency balance at 100× magnification. The configurable settings intended to underscore different cell wall properties indeed changed the absolute levels and intra- and inter-annual patterns of CWT. This versatility, together with the high data production capacity, allows to tailor the measurements of CWT to the specific goal of each study, which opens new research perspectives, e.g., for investigating structure-function relationships, tree stress responses and carbon allocation patterns, and for reconstructing climate based on intra- and inter-annual variability of anatomical wood density. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

    PubMed Central

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

    2011-01-01

    The increased thickness of the carotid wall >1 mm is a significant predictor of coronary and cerebrovascular diseases. The purpose of our study was to assess the agreement between multidetector row computed tomography angiography (MDCTA) in measuring carotid artery wall thickness (CAWT) and color Doppler ultrasound (CD-US) in measuring intimae-media thickness (IMT). Eighty-nine patients (aged 35–81) were prospectively analyzed using a 64-detector MDCTA and a CD-US scanner. Continuous data 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. PMID:22224072

  4. Risk Assessment of Abdominal Wall Thickness Measured on Pre-Operative Computerized Tomography for Incisional Surgical Site Infection after Abdominal Surgery.

    PubMed

    Tongyoo, Assanee; Chatthamrak, Putipan; Sriussadaporn, Ekkapak; Limpavitayaporn, Palin; Mingmalairak, Chatchai

    2015-07-01

    The surgical site infection (SSI) is a common complication of abdominal operation. It relates to increased hospital stay, increased healthcare cost, and decreased patient's quality of life. Obesity, usually defined by BMI, is known as one of the risks of SSI. However, the thickness of subcutaneous layers of abdominal wall might be an important local factor affecting the rate of SSI after the abdominal operations. The objective of this study is to assess the importance of the abdominal wall thickness on incisional SSI rate. The subjects of the present study were patients who had undergone major abdominal operations at Thammasat University Hospital between June 2013 and May 2014, and had been investigated with CT scans before their operations. The demographic data and clinical information of these patients were recorded. The thickness ofsubcutaneous fatty tissue from skin down to the most superficial layer of abdominal wall muscle at the surgical site was measured on CT images. The wound infectious complication was reviewed and categorized as superficial and deep incisional SSIfollowing the definition from Centersfor Disease Control and Prevention (CDC) guidelines. The significance ofeach potentialfactors on SSI rates was determined separately with student t-test for quantitative data and χ2-test for categorical data. Then all factors, which had p < 0.10, were included into the multivariate logistic regression analysis and were analyzed with significance at p < 0.05. One hundred and thirty-nine patients were included in this study. They all underwent major abdominal surgery and had had pre-operative CTscans. Post-operative SSI was 25.2% (35/139), superficial and deep types in 27 and 8 patients, respectively. The comparison of abdominal wall thickness between patients with and without infection was significantly different (20.0 ± 8.4 mm and 16.0 ± 7.2 mm, respectively). When the thickness at 20 mm was used as the cut-off value, 43 of 139 patients had abdominal wall

  5. A thermoelastic transversely isotropic thick walled cylinder/disk application: An analytical solution and study

    NASA Technical Reports Server (NTRS)

    Arnold, S. M.

    1989-01-01

    A continuum theory is utilized to represent the thermoelastic behavior of a thick walled composite cylinder that can be idealized as transversely isotropic. A multiaxial statement of the constitutive theory employed is presented, as well as the out of the plane of isotropy, plane stress, and plane strain reductions. The derived analytical solution presented is valid for a cylindrical tube or thin disk with a concentric hole, subjected to internal and/or external pressure and a general radial temperature distribution. A specific problem examined is that of a thick walled cylinder subjected to an internal and external pressure loading and a linear radial temperature distribution. The results are expressed in nondimensional form and the effects on the response behavior are examined for various material properties, fiber orientation and types of loadings.

  6. Noninvasive evaluation of gastric emptying and gastric wall thickness in SLE patients.

    PubMed

    Shen, Hao-Lin; Yang, Shu-Ping; Wang, Kang-Jian; Huang, Bei-Lei; Huang, Wen-Bao; Wu, Jin-Zhi; Lyu, Guo-Rong

    2017-04-01

    The objective of this study is to evaluate the gastric emptying in patients with systemic lupus erythematosus (SLE) with gastrointestinal involvement using three-dimensional (3D) ultrasonography. The gastric emptying times at 25% (T1), 50% (T2), and 75% (T3) of SLE patients with gastrointestinal involvement (n = 40) and healthy controls (n = 80) were evaluated and compared. In addition, the correlations among the gastric wall thickness, SLE disease activity index (SLEDAI), and upper gastrointestinal symptoms were calculated. The gastric wall thickness was correlated with the SLEDAI (r = 0.928, p < 0.001) and the upper gastrointestinal symptom index (r = 0.848, p < 0.001). The emptying times T1, T2, and T3 of the SLE patients were 17.08 ± 2.65 min (mean ± standard deviation), 39.85 ± 6.54 min, and 83.58 ± 7.12 min, respectively. For healthy controls, they were 19.65 ± 5.39 min, 41.08 ± 7.51 min, and 70.34 ± 8.03 min. The T1 of the SLE patients was shorter (p < 0.01), while the T3 was longer (p < 0.001). Moreover, T3 in the SLE group had the best correlation with the upper gastrointestinal symptom index (r = 0.553, p < 0.001). T1 in the SLE group was anti-correlated with early satiety (r = -0.366, p < 0.05). Combining the emptying times T1 and T3, as well as the gastric wall thickness, the SLEDAI and the upper gastrointestinal symptoms index can provide accurate clinical diagnosis of SLE with gastric involvement.

  7. The influence of head diameter and wall thickness on deformations of metallic acetabular press-fit cups and UHMWPE liners: a finite element analysis.

    PubMed

    Goebel, Paul; Kluess, Daniel; Wieding, Jan; Souffrant, Robert; Heyer, Horst; Sander, Manuela; Bader, Rainer

    2013-03-01

    To increase the range of motion of total hip endoprostheses, prosthetic heads need to be enlarged, which implies that the cup and/or liner thickness must decrease. This may have negative effects on the wear rate, because the acetabular cups and liners could deform during press-fit implantation and hip joint loading. We compared the metal cup and polyethylene liner deformations that occurred when different wall thicknesses were used in order to evaluate the resulting changes in the clearance of the articulating region. A parametric finite element model utilized three cup and liner wall thicknesses to analyze cup and liner deformations after press-fit implantation into the pelvic bone. The resultant hip joint force during heel strike was applied while the femur was fixed, accounting for physiological muscle forces. The deformation behavior of the liner under joint loading was therefore assessed as a function of the head diameter and the resulting clearance. Press-fit implantation showed diametral cup deformations of 0.096, 0.034, and 0.014 mm for cup wall thicknesses of 3, 5, and 7 mm, respectively. The largest deformations (average 0.084 ± 0.003 mm) of liners with thicknesses of 4, 6, and 8 mm occurred with the smallest cup wall thickness (3 mm). The smallest liner deformation (0.011 mm) was obtained with largest cup and liner wall thicknesses. Under joint loading, liner deformations in thin-walled acetabular cups (3 mm) reduced the initial clearance by about 50 %. Acetabular press-fit cups with wall thicknesses of ≤5 mm should only be used in combination with polyethylene liners >6 mm thick in order to minimize the reduction in clearance.

  8. SIP Shear Walls: Cyclic Performance of High-Aspect-Ratio Segments and Perforated Walls

    Treesearch

    Vladimir Kochkin; Douglas R. Rammer; Kevin Kauffman; Thomas Wiliamson; Robert J. Ross

    2015-01-01

    Increasing stringency of energy codes and the growing market demand for more energy efficient buildings gives structural insulated panel (SIP) construction an opportunity to increase its use in commercial and residential buildings. However, shear wall aspect ratio limitations and lack of knowledge on how to design SIPs with window and door openings are barriers to the...

  9. Clinical efficiency of Piezo-ICSI using micropipettes with a wall thickness of 0.625 μm.

    PubMed

    Hiraoka, Kenichiro; Kitamura, Seiji

    2015-12-01

    The purposes of the present study are to assess the clinical efficiency of Piezo-intracytoplasmic sperm injection (ICSI) and to improve the Piezo-ICSI method for human oocytes. We examined three ICSI methods to determine their clinical efficiency by comparing the survival, fertilization, good-quality day-3 embryo, pregnancy, and live birth rates. The three ICSI methods tested were conventional ICSI (CI) (using beveled spiked micropipettes with a wall thickness of 1 μm), conventional Piezo-ICSI (CPI) (using flat-tipped micropipettes with a wall thickness of 0.925 μm), and improved Piezo-ICSI (IPI) (using flat-tipped micropipettes with a wall thickness of 0.625 μm). We collectively investigated 2020 mature oocytes retrieved from 437 patients between October 2010 and January 2014. The survival rates after CI, CPI, and IPI were 90, 95, and 99 %, respectively. The fertilization rates after CI, CPI, and IPI were 68, 75, and 89 %, respectively. The good-quality day-3 embryo rates after CI, CPI, and IPI were 37, 43, and 55 %, respectively. The pregnancy rates after the transfer of good-quality day-3 embryo of CI, CPI, and IPI were 19, 21, and 31 %, respectively. The live birth rates of CI, CPI, and IPI were 15, 16, and 25 %, respectively. Significantly higher survival, fertilization, good-quality day-3 embryo, pregnancy, and live birth rates were obtained using IPI. When comparing the IPI to the CI and CPI, the results revealed that the Piezo-ICSI using flat-tipped micropipettes with a wall thickness of 0.625 μm significantly improves survival, fertilization, good-quality day-3 embryo, pregnancy, and live birth rates.

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

    PubMed

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

    2014-06-01

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

  11. Is the necrosis/wall ADC ratio useful for the differentiation of benign and malignant breast lesions?

    PubMed

    Durur-Subasi, Irmak; Durur-Karakaya, Afak; Karaman, Adem; Seker, Mehmet; Demirci, Elif; Alper, Fatih

    2017-05-01

    To determine whether the necrosis/wall apparent diffusion coefficient (ADC) ratio is useful for the malignant-benign differentiation of necrotic breast lesions. Breast MRI was performed using a 3-T system. In this retrospective study, calculation of the necrosis/wall ADC ratio was based on ADC values measured from the necrosis and from the wall of malignant and benign breast lesions by diffusion-weighted imaging (DWI). By synchronizing post-contrast T 1 weighted images, the separate parts of wall and necrosis were maintained. All the diagnoses were pathologically confirmed. Statistical analyses were conducted using an independent sample t-test and receiver operating characteristic analysis. The intraclass and interclass correlations were evaluated. A total of 66 female patients were enrolled, 38 of whom had necrotic breast carcinomas and 28 of whom had breast abscesses. The ADC values were obtained from both the wall and necrosis. The mean necrosis/wall ADC ratio (± standard deviation) was 1.61 ± 0.51 in carcinomas, and it was 0.65 ± 0.33 in abscesses. The area under the curve values for necrosis ADC, wall ADC and the necrosis/wall ADC ratio were 0.680, 0.068 and 0.942, respectively. A wall/necrosis ADC ratio cut-off value of 1.18 demonstrated a sensitivity of 97%, specificity of 93%, a positive-predictive value of 95%, a negative-predictive value of 96% and an accuracy of 95% in determining the malignant nature of necrotic breast lesions. There was a good intra- and interclass reliability for the ADC values of both necrosis and wall. The necrosis/wall ADC ratio appears to be a reliable and promising tool for discriminating breast carcinomas from abscesses using DWI. Advances in knowledge: ADC values of the necrosis obtained by DWI are valuable for malignant-benign differentiation in necrotic breast lesions. The necrosis/wall ADC ratio appears to be a reliable and promising tool in the breast imaging field.

  12. Is the necrosis/wall ADC ratio useful for the differentiation of benign and malignant breast lesions?

    PubMed Central

    Durur-Karakaya, Afak; Karaman, Adem; Seker, Mehmet; Demirci, Elif; Alper, Fatih

    2017-01-01

    Objective: To determine whether the necrosis/wall apparent diffusion coefficient (ADC) ratio is useful for the malignant–benign differentiation of necrotic breast lesions. Methods: Breast MRI was performed using a 3-T system. In this retrospective study, calculation of the necrosis/wall ADC ratio was based on ADC values measured from the necrosis and from the wall of malignant and benign breast lesions by diffusion-weighted imaging (DWI). By synchronizing post-contrast T1 weighted images, the separate parts of wall and necrosis were maintained. All the diagnoses were pathologically confirmed. Statistical analyses were conducted using an independent sample t-test and receiver operating characteristic analysis. The intraclass and interclass correlations were evaluated. Results: A total of 66 female patients were enrolled, 38 of whom had necrotic breast carcinomas and 28 of whom had breast abscesses. The ADC values were obtained from both the wall and necrosis. The mean necrosis/wall ADC ratio (± standard deviation) was 1.61 ± 0.51 in carcinomas, and it was 0.65 ± 0.33 in abscesses. The area under the curve values for necrosis ADC, wall ADC and the necrosis/wall ADC ratio were 0.680, 0.068 and 0.942, respectively. A wall/necrosis ADC ratio cut-off value of 1.18 demonstrated a sensitivity of 97%, specificity of 93%, a positive-predictive value of 95%, a negative-predictive value of 96% and an accuracy of 95% in determining the malignant nature of necrotic breast lesions. There was a good intra- and interclass reliability for the ADC values of both necrosis and wall. Conclusion: The necrosis/wall ADC ratio appears to be a reliable and promising tool for discriminating breast carcinomas from abscesses using DWI. Advances in knowledge: ADC values of the necrosis obtained by DWI are valuable for malignant-benign differentiation in necrotic breast lesions. The necrosis/wall ADC ratio appears to be a reliable and promising tool in the breast imaging field. PMID

  13. Charged magnetic domain walls as observed in nanostructured thin films: dependence on both film thickness and anisotropy.

    PubMed

    Favieres, C; Vergara, J; Madurga, V

    2013-02-13

    The magnetic domain configurations of soft magnetic, nanostructured, pulsed laser-deposited Co films were investigated. Their dependence on both the thickness t (20 nm ≤ t ≤ 200 nm) and the anisotropy was studied. Charged zigzag walls, with a characteristic saw-tooth vertex angle θ, were observed. θ changed with t from θ ≈ 17° to ≈25°, presenting an intermediate sharp maximum that has not been described before. The reduced length of the zigzag walls also exhibited a peak at t ≈ 70 nm. The relationship between the total reduced length and the density energy of the magnetic wall allowed us to establish a change from a Néel-type to a Bloch-type core of the zigzag walls at this thickness, t ≈ 70 nm. We also accounted for the magnetic energy arising from the surface roughness of the thinner films after imaging the film surface morphologies. Moreover, this distinctive behaviour of the zigzag walls of these low-anisotropy films was compared to that of high-anisotropy films.

  14. Tissue factor levels and the fibrinolytic system in thin and thick intraluminal thrombus and underlying walls of abdominal aortic aneurysms.

    PubMed

    Siennicka, Aldona; Zuchowski, Marta; Kaczmarczyk, Mariusz; Cnotliwy, Miłosław; Clark, Jeremy Simon; Jastrzębska, Maria

    2018-03-20

    The hemostatic system cooperates with proteolytic degradation in processes allowing abdominal aortic aneurysm (AAA) formation. In previous studies, it has been suggested that aneurysm rupture depends on intraluminal thrombus (ILT) thickness, which varies across each individual aneurysm. We hypothesized that hemostatic components differentially accumulate in AAA tissue in relation to ILT thickness. Thick (A1) and thin (B1) segments of ILTs and aneurysm wall sections A (adjacent to A1) and B (adjacent to B1) from one aneurysm sac were taken from 35 patients undergoing elective repair. Factor levels were measured using enzyme-linked immunosorbent assay of protein extract. Tissue factor (TF) activities were significantly higher in thinner segments of AAA (B1 vs A1, P = .003; B vs A, P < .001; B vs A1, P < .001; B vs B1, P = .001). Significantly higher tissue plasminogen activator was found in thick thrombus-covered wall segments (A) than in B, A1, and B1 (P = .015, P < .001, and P < .001, respectively). Plasminogen concentrations were highest in ILT. Concentrations of α 2 -antiplasmin in thin ILT adjacent walls (B) were higher compared with wall (A) adjacent to thick ILT (P = .021) and thick ILT (A1; P < .001). Significant correlations between levels of different factors were mostly found in thick ILT (A1). However, no correlations were found at B sites, except for a correlation between plasmin and TF activities (r = 0.55; P = .004). These results suggest that higher TF activities are present in thinner AAA regions. These parameters and local fibrinolysis may be part of the processes leading to destruction of the aneurysm wall. Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

  15. Measurement of three-dimensional normal vectors, principal curvatures, and wall thickness of the heart using cine-MRI

    NASA Astrophysics Data System (ADS)

    Coghlan, Leslie; Singleton, H. R.; Dell'Italia, L. J.; Linderholm, C. E.; Pohost, G. M.

    1995-05-01

    We have developed a method for measuring the detailed in vivo three dimensional geometry of the left and right ventricles using cine-magnetic resonance imaging. From data in the form of digitized short axis outlines, the normal vectors, principal curvatures and directions, and wall thickness were computed. The method was evaluated on simulated ellipsoids and on human MRI data. Measurements of normal vectors and of wall thickness were very accurate in simulated data and appeared appropriate in patient data. On simulated data, measurements of the principal curvature k1 (corresponding approximately to the short axis direction of the left ventricle) and of principal directions were quite accurate, but measurements of the other principal curvature (k2) were less accurate. The reasons behind this are considered. We expect improvements in the accuracy with thinner slices and improved representation of the surface data. Gradient echo images were acquired from 8 dogs with a 1.5T system (Philips Gyroscan) at baseline and four months after closed chest experimentally produced mitral regurgitation (MR). The product (k1 + k2) X wall thickness averaged over all slices at end-diastole was significantly lower after surgery (n equals 8, p < 0.005). These geometry changes were consistent with the expected increase in wall stress after MR.

  16. Effects of thickness, insulation, and surface color on the net heat loss through an adobe wall

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Herman, R.W.

    1980-01-01

    A finite difference computer program was written and run to study the net thermal losses through a large variety of adobe walls. Fifty-four different combinations of surface color, wall thickness, and insulation position and R value were modeled over a typical two week winter period for locations similar to Albuquerque, New Mexico. A transient analysis of the heat loss from the room to the interior wall surface was compared to both conventional U value and steady-state calculations.

  17. Correlation between capillary oxygen saturation and small intestinal wall thickness in the equine colic patient

    PubMed Central

    Mirle, Elisabeth; Wogatzki, Anna; Kunzmann, Robert; Schoenfelder, Axel M; Litzke, Lutz F

    2017-01-01

    The surgical evaluation of haemorrhagic infarcted intestine and the decision for or against bowel resection require a lot of experience and are subjective. The aim of this prospective, clinical study was to examine the correlation between oxygen saturation and small intestinal wall (IW) thickness, using two objective methods. In 22 colicky horses, the blood flow, oxygen saturation and relative amount of haemoglobin were measured intraoperatively via laser Doppler and white light spectroscopy (O2C, oxygen to see, LEA Medizintechnik) at six measuring points (MPs) in small and large intestines. Furthermore, the IW thickness was measured ultrasonographically. Nine of 22 horses had an increased small IW thickness greater than 4 mm (Freeman 2002, Scharner and others 2002, le Jeune and Whitcomb 2014) at measuring point 1 (MP1) (strangulated segment), four horses had a thickened bowel wall at measuring point 3 (MP3) (poststenotic) and one at measuring point 2 (MP2). The oxygen saturation was 0 at MP1 in six horses, at MP3 in two horses and at MP2 (prestenotic) in one. Oxygen saturation and small IW thickness were independent of each other at MP1 and MP2. At MP3, the two parameters were negatively correlated. In summary, it is not possible to draw conclusions about oxygen saturation based on IW thickness. PMID:28761667

  18. Correlation between capillary oxygen saturation and small intestinal wall thickness in the equine colic patient.

    PubMed

    Mirle, Elisabeth; Wogatzki, Anna; Kunzmann, Robert; Schoenfelder, Axel M; Litzke, Lutz F

    2017-01-01

    The surgical evaluation of haemorrhagic infarcted intestine and the decision for or against bowel resection require a lot of experience and are subjective. The aim of this prospective, clinical study was to examine the correlation between oxygen saturation and small intestinal wall (IW) thickness, using two objective methods. In 22 colicky horses, the blood flow, oxygen saturation and relative amount of haemoglobin were measured intraoperatively via laser Doppler and white light spectroscopy (O2C, oxygen to see, LEA Medizintechnik) at six measuring points (MPs) in small and large intestines. Furthermore, the IW thickness was measured ultrasonographically. Nine of 22 horses had an increased small IW thickness greater than 4 mm (Freeman 2002, Scharner and others 2002, le Jeune and Whitcomb 2014) at measuring point 1 (MP1) (strangulated segment), four horses had a thickened bowel wall at measuring point 3 (MP3) (poststenotic) and one at measuring point 2 (MP2). The oxygen saturation was 0 at MP1 in six horses, at MP3 in two horses and at MP2 (prestenotic) in one. Oxygen saturation and small IW thickness were independent of each other at MP1 and MP2. At MP3, the two parameters were negatively correlated. In summary, it is not possible to draw conclusions about oxygen saturation based on IW thickness.

  19. New portable pipe wall thickness measuring technique

    NASA Astrophysics Data System (ADS)

    Pascente, Joseph E.

    1998-03-01

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

  20. Ceramic inlays and partial ceramic crowns: influence of remaining cusp wall thickness on the marginal integrity and enamel crack formation in vitro.

    PubMed

    Krifka, Stephanie; Anthofer, Thomas; Fritzsch, Marcus; Hiller, Karl-Anton; Schmalz, Gottfried; Federlin, Marianne

    2009-01-01

    No information is currently available about what the critical cavity wall thickness is and its influence upon 1) the marginal integrity of ceramic inlays (CI) and partial ceramic crowns (PCC) and 2) the crack formation of dental tissues. This in vitro study of CI and PCC tested the effects of different remaining cusp wall thicknesses on marginal integrity and enamel crack formation. CI (n = 25) and PCC (n = 26) preparations were performed in extracted human molars. Functional cusps of CI and PCC were adjusted to a 2.5 mm thickness; for PCC, the functional cusps were reduced to a thickness of 2.0 mm. Non-functional cusps were adjusted to wall thicknesses of 1) 1.0 mm and 2) 2.0 mm. Ceramic restorations (Vita Mark II, Cerec3 System) were fabricated and adhesively luted to the cavities with Excite/Variolink II. The specimens were exposed to thermocycling and central mechanical loading (TCML: 5000 x 5 degrees C-55 degrees C; 30 seconds/cycle; 500000 x 72.5N, 1.6Hz). Marginal integrity was assessed by evaluating a) dye penetration (fuchsin) on multiple sections after TCML and by using b) quantitative margin analysis in the scanning electron microscope (SEM) before and after TCML. Ceramic- and tooth-luting agent interfaces (LA) were evaluated separately. Enamel cracks were documented under a reflective light microscope. The data were statistically analyzed with the Mann Whitney U-test (alpha = 0.05) and the Error Rates Method (ERM). Crack formation was analyzed with the Chi-Square-test (alpha = 0.05) and ERM. In general, the remaining cusp wall thickness, interface, cavity design and TCML had no statistically significant influence on marginal integrity for both CI and PCC (ERM). Single pairwise comparisons showed that the CI and PCC of Group 2 had a tendency towards less microleakage along the dentin/LA interface than Group 1. Cavity design and location had no statistically significant influence on crack formation, but the specimens with 1.0 mm of remaining wall

  1. Quantitative evaluation of the relationship between dorsal wall length, sole thickness, and rotation of the distal phalanx in the bovine claw using computed tomography.

    PubMed

    Tsuka, T; Murahata, Y; Azuma, K; Osaki, T; Ito, N; Okamoto, Y; Imagawa, T

    2014-10-01

    Computed tomography (CT) was performed on 800 untrimmed claws (400 inner claws and 400 outer claws) of 200 pairs of bovine hindlimbs to investigate the relationships between dorsal wall length and sole thickness, and between dorsal wall length and the relative rotation angle of distal phalanx-to-sole surface (S-D angle). Sole thickness was 3.8 and 4.0 mm at the apex of the inner claws and outer claws, respectively, with dorsal wall lengths <70 mm. These sole thickness values were less than the critical limit of 5 mm, which is associated with a softer surface following thinning of the soles. A sole thickness of 5 mm at the apex was estimated to correlate with dorsal wall lengths of 72.1 and 72.7 mm for the inner and outer claws, respectively. Sole thickness was 6.1 and 6.4 mm at the apex of the inner and outer claws, respectively, with dorsal wall lengths of 75 mm. These sole thickness values were less than the recommended sole thickness of 7 mm based on the protective function of the soles. A sole thickness >7 mm at the apex was estimated to correlate with a dorsal wall length of 79.8 and 78.4mm for the inner and outer claws, respectively. The S-D angles were recorded as anteversions of 2.9° and 4.7° for the inner and outer claws, respectively, with a dorsal wall length of 75 mm. These values indicate that the distal phalanx is likely to have rotated naturally forward toward the sole surface. The distal phalanx rotated backward to the sole surface at 3.2° and 7.6° for inner claws with dorsal wall lengths of 90-99 and ≥100 mm, respectively; and at 3.5° for outer claws with a dorsal wall length ≥100 mm. Dorsal wall lengths of 85.7 and 97.2 mm were estimated to correlate with a parallel positional relationship of the distal phalanx to the sole surface in the inner and outer claws, respectively. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  2. Behavior of turbulent boundary layers on curved convex walls

    NASA Technical Reports Server (NTRS)

    Schmidbauer, Hans

    1936-01-01

    The system of linear differential equations which indicated the approach of separation and the so-called "boundary-layer thickness" by Gruschwitz is extended in this report to include the case where the friction layer is subject to centrifugal forces. Evaluation of the data yields a strong functional dependence of the momentum change and wall drag on the boundary-layer thickness radius of curvature ratio for the wall. It is further shown that the transition from laminar to turbulent flow occurs at somewhat higher Reynolds Numbers at the convex wall than at the flat plate, due to the stabilizing effect of the centrifugal forces.

  3. Influence of ceramic dental crown coating substrate thickness ratio on strain energy release rate

    NASA Astrophysics Data System (ADS)

    Khasnulhadi, K.; Daud, R.; Mat, F.; Noor, S. N. F. M.; Basaruddin, K. S.; Sulaiman, M. H.

    2017-10-01

    This paper presents the analysis of coating substrate thickness ratio effect on the crown coating fracture behaviour. The bi-layer material is examined under four point bending with pre-crack at the bottom of the core material by using finite element. Three different coating thickness of core/substrate was tested which is 1:1, 1:2 and 2:1. The fracture parameters are analysed based on bilayer and homogenous elastic interaction. The result shows that the ratio thickness of core/veneer provided a significant effect on energy release rate.

  4. 3D mapping of airway wall thickening in asthma with MSCT: a level set approach

    NASA Astrophysics Data System (ADS)

    Fetita, Catalin; Brillet, Pierre-Yves; Hartley, Ruth; Grenier, Philippe A.; Brightling, Christopher

    2014-03-01

    Assessing the airway wall thickness in multi slice computed tomography (MSCT) as image marker for airway disease phenotyping such asthma and COPD is a current trend and challenge for the scientific community working in lung imaging. This paper addresses the same problem from a different point of view: considering the expected wall thickness-to-lumen-radius ratio for a normal subject as known and constant throughout the whole airway tree, the aim is to build up a 3D map of airway wall regions of larger thickness and to define an overall score able to highlight a pathological status. In this respect, the local dimension (caliber) of the previously segmented airway lumen is obtained on each point by exploiting the granulometry morphological operator. A level set function is defined based on this caliber information and on the expected wall thickness ratio, which allows obtaining a good estimate of the airway wall throughout all segmented lumen generations. Next, the vascular (or mediastinal dense tissue) contact regions are automatically detected and excluded from analysis. For the remaining airway wall border points, the real wall thickness is estimated based on the tissue density analysis in the airway radial direction; thick wall points are highlighted on a 3D representation of the airways and several quantification scores are defined. The proposed approach is fully automatic and was evaluated (proof of concept) on a patient selection coming from different databases including mild, severe asthmatics and normal cases. This preliminary evaluation confirms the discriminative power of the proposed approach regarding different phenotypes and is currently extending to larger cohorts.

  5. Stress intensity factors in a reinforced thick-walled cylinder

    NASA Technical Reports Server (NTRS)

    Tang, R.; Erdogan, F.

    1984-01-01

    An elastic thick-walled cylinder containing a radial crack is considered. It is assumed that the cylinder is reinforced by an elastic membrane on its inner surface. The model is intended to simulate pressure vessels with cladding. The formulation of the problem is reduced to a singular integral equation. Various special cases including that of a crack terminating at the cylinder-reinforcement interface are investigated and numerical examples are given. Results indicate that in the case of the crack touching the interface the crack surface displacement derivative is finite and consequently the stress state around the corresponding crack tip is bounded; and generally, for realistic values of the stiffness parameter, the effect of the reinforcement is not very significant.

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

    PubMed Central

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

    2014-01-01

    Objective. To compare bladder wall thickness in two kinds of urinary incontinent women—stress urinary incontinence (SUI) and overactive bladder (OAB) with urodynamic detrusor overactivity (DO), and to compare them with continent patients by ultrasound, also, correlate with cystometric results in incontinent women. Methods. 91 women were divided into the following groups: continent (n = 31), SUI (n = 30), and DO (n = 30) groups after clinical evaluation and urodynamic test (only in incontinent women). Transvaginal ultrasound was performed to the bladder wall thickness (BWT) measurement. The mean of BWT was calculated and data were analyzed with ANOVA and Turkey's multiple comparison tests. Pearson's correlation coefficient (r) was used to compare two variables. Receiver operating characteristic (ROC) curve was performed to study BWT as a diagnostic parameter. Results. BWT in DO group was significantly higher than that in the other groups (P < 0.005). A moderate positive correlation was found between BWT and maximum bladder pressure during involuntary bladder contraction. There was no difference in BWT between SUI and continent groups. DO group had lower first desire to void and cystometric capacity. Maximum bladder pressure at detrusor contraction had a moderate positive correlation with BWT. The ROC revealed an area under the curve of 0.962 (95% CI, 0.90–1.01). Conclusions. DO patients have increased bladder wall thickness, lower first desire to void, and lower cystometric capacity. There was a moderate correlation between BWT and maximum bladder pressure during involuntary bladder contraction. PMID:25538959

  7. Flow characteristics and scaling past highly porous wall-mounted fences

    NASA Astrophysics Data System (ADS)

    Rodríguez-López, Eduardo; Bruce, Paul J. K.; Buxton, Oliver R. H.

    2017-07-01

    An extensive characterization of the flow past wall-mounted highly porous fences based on single- and multi-scale geometries has been performed using hot-wire anemometry in a low-speed wind tunnel. Whilst drag properties (estimated from the time-averaged momentum equation) seem to be mostly dependent on the grids' blockage ratio; wakes of different size and orientation bars seem to generate distinct behaviours regarding turbulence properties. Far from the near-grid region, the flow is dominated by the presence of two well-differentiated layers: one close to the wall dominated by the near-wall behaviour and another one corresponding to the grid's wake and shear layer, originating from between this and the freestream. It is proposed that the effective thickness of the wall layer can be inferred from the wall-normal profile of root-mean-square streamwise velocity or, alternatively, from the wall-normal profile of streamwise velocity correlation. Using these definitions of wall-layer thickness enables us to collapse different trends of the turbulence behaviour inside this layer. In particular, the root-mean-square level of the wall shear stress fluctuations, longitudinal integral length scale, and spanwise turbulent structure is shown to display a satisfactory scaling with this thickness rather than with the whole thickness of the grid's wake. Moreover, it is shown that certain grids destroy the spanwise arrangement of large turbulence structures in the logarithmic region, which are then re-formed after a particular streamwise extent. It is finally shown that for fences subject to a boundary layer of thickness comparable to their height, the effective thickness of the wall layer scales with the incoming boundary layer thickness. Analogously, it is hypothesized that the growth rate of the internal layer is also partly dependent on the incoming boundary layer thickness.

  8. Crustal thickness and vP/vS ratio in Shanxi Graben, China

    NASA Astrophysics Data System (ADS)

    Shi, Yutao; Gao, Yuan; Jing, Honglin

    2014-12-01

    Shanxi Graben is in the middle part of the North China Craton, from south to north. With the teleseismic data recorded by Regional Seismograph Networks and the temporary ZBnet-W Seismic Array around east part of Shanxi Graben, we measured the crustal thickness and v P/ v S ratio beneath each station using the H-κ stack of receiver functions. The observed crustal thickness shows obvious lateral variation, increasing gradually from east to west in the Shanxi Graben. Beneath the Shanxi Graben the crust is relatively thicker than both sides of the south and the north. In addition, the v P/ v S ratio in the north of study zone is higher than that in the south. The highest v P/ v S ratio exists in the crust of the Xinding basin and the Datong basin. Our study also suggests that high velocity ratio might result from the strong activities of the magmation and volcanism.

  9. Fracture resistance of welded thick-walled high-pressure vessels in power plants. Report No. 2. Approach to evaluating static strength

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gorynin, I.V.; Filatov, V.M.; Ignatov, V.A.

    1986-07-01

    The authors examine data on the effect of defects on the fracture resistance of high-pressure vessels and their models obtained within the framework of the HSST program. Results of internal-pressure tests of two types of vessels with a wall thickness of 152 mm made from forgings of steels SA508 and SA533, as well as small vessels with a wall thickness of 11.5 and 23mm made of steel SA533 are shown. The authors state that testing thick-walled welded high-pressure vessels and thin-walled vessels with surface defects of different sizes has demonstrated that there are substantial static-strength reserves in structures designed bymore » existing domestic and foreign standards on the strength of power-plant equipment. A correction was proposed for the presently used method of calculating the resistance of highpressure vessels to brittle fracture that allows for the dimensions of the defects in relation to the type of vessel, the manufacturing technology, and the method of inspection.« less

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  11. Impact of Age and Aerobic Exercise Training on Conduit Artery Wall Thickness: Role of the Shear Pattern.

    PubMed

    Tanahashi, Koichiro; Kosaki, Keisei; Sawano, Yuriko; Yoshikawa, Toru; Tagawa, Kaname; Kumagai, Hiroshi; Akazawa, Nobuhiko; Maeda, Seiji

    2017-01-01

    Hemodynamic shear stress is the frictional force of blood on the arterial wall. The shear pattern in the conduit artery affects the endothelium and may participate in the development and progression of atherosclerosis. We investigated the role of the shear pattern in age- and aerobic exercise-induced changes in conduit artery wall thickness via cross-sectional and interventional studies. In a cross-sectional study, we found that brachial shear rate patterns and brachial artery intima-media thickness (IMT) correlated with age. Additionally, brachial artery shear rate patterns were associated with brachial artery IMT in 102 middle-aged and older individuals. In an interventional study, 39 middle-aged and older subjects were divided into 2 groups: control and exercise. The exercise group completed 12 weeks of aerobic exercise training. Aerobic exercise training significantly increased the antegrade shear rate and decreased the retrograde shear rate and brachial artery IMT. Moreover, changes in the brachial artery antegrade shear rate and the retrograde shear rate correlated with the change in brachial artery IMT. The results of the present study indicate that changes in brachial artery shear rate patterns may contribute to age- and aerobic exercise training-induced changes in brachial artery wall thickness. © 2017 S. Karger AG, Basel.

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

    PubMed

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

    2016-01-01

    Decreased diffusing capacity of the lung for carbon monoxide (DLCO) is associated with emphysema. DLCO is also related to decreased arterial oxygen tension (PaO2), but there are limited data on associations between PaO2 and computed tomography (CT) derived measures of emphysema and airway wall thickness. To examine whether CT measures of emphysema and airway wall thickness are associated with level of arterial oxygen tension beyond that provided by measurements of diffusion capacity and spirometry. The study sample consisted of 271 smoking or ex-smoking COPD patients from the Bergen COPD Cohort Study examined in 2007-2008. Emphysema was assessed as percent of low-attenuation areas<-950 Hounsfield units (%LAA), and airway wall thickness as standardised measure at an internal perimeter of 10 mm (AWT-Pi10). Multiple linear regression models were fitted with PaO2 as the outcome variable, and %LAA, AWT-Pi10, DLCO and carbon monoxide transfer coefficient (KCO) as main explanatory variables. The models were adjusted for sex, age, smoking status, and haemoglobin concentration, as well as forced expiratory volume in one second (FEV1). Sixty two per cent of the subjects were men, mean (SD) age was 64 (7) years, mean (SD) FEV1 in percent predicted was 50 (15)%, and mean PaO2 (SD) was 9.3 (1.1) kPa. The adjusted regression coefficient (CI) for PaO2 was -0.32 (-0.04-(-0.019)) per 10% increase in %LAA (p<0.01). When diffusion capacity and FEV1 were added to the model, respectively, the association lost its statistical significance. No relationship between airway wall thickness and PaO2 was found. CT assessment of airway wall thickness is not associated with arterial oxygen tension in COPD patients. Emphysema score measured by chest CT, is related to decreased PaO2, but cannot replace measurements of diffusion capacity in the clinical evaluation of hypoxaemia.

  13. Estimating crustal thickness and Vp/Vs ratio with joint constraints of receiver function and gravity data

    NASA Astrophysics Data System (ADS)

    Shi, Lei; Guo, Lianghui; Ma, Yawei; Li, Yonghua; Wang, Weilai

    2018-05-01

    The technique of teleseismic receiver function H-κ stacking is popular for estimating the crustal thickness and Vp/Vs ratio. However, it has large uncertainty or ambiguity when the Moho multiples in receiver function are not easy to be identified. We present an improved technique to estimate the crustal thickness and Vp/Vs ratio by joint constraints of receiver function and gravity data. The complete Bouguer gravity anomalies, composed of the anomalies due to the relief of the Moho interface and the heterogeneous density distribution within the crust, are associated with the crustal thickness, density and Vp/Vs ratio. According to their relationship formulae presented by Lowry and Pérez-Gussinyé, we invert the complete Bouguer gravity anomalies by using a common algorithm of likelihood estimation to obtain the crustal thickness and Vp/Vs ratio, and then utilize them to constrain the receiver function H-κ stacking result. We verified the improved technique on three synthetic crustal models and evaluated the influence of selected parameters, the results of which demonstrated that the novel technique could reduce the ambiguity and enhance the accuracy of estimation. Real data test at two given stations in the NE margin of Tibetan Plateau illustrated that the improved technique provided reliable estimations of crustal thickness and Vp/Vs ratio.

  14. Measurement of thickness of film deposited on the plasma-facing wall in the QUEST tokamak by colorimetry.

    PubMed

    Wang, Z; Hanada, K; Yoshida, N; Shimoji, T; Miyamoto, M; Oya, Y; Zushi, H; Idei, H; Nakamura, K; Fujisawa, A; Nagashima, Y; Hasegawa, M; Kawasaki, S; Higashijima, A; Nakashima, H; Nagata, T; Kawaguchi, A; Fujiwara, T; Araki, K; Mitarai, O; Fukuyama, A; Takase, Y; Matsumoto, K

    2017-09-01

    After several experimental campaigns in the Kyushu University Experiment with Steady-state Spherical Tokamak (QUEST), the originally stainless steel plasma-facing wall (PFW) becomes completely covered with a deposited film composed of mixture materials, such as iron, chromium, carbon, and tungsten. In this work, an innovative colorimetry-based method was developed to measure the thickness of the deposited film on the actual QUEST wall. Because the optical constants of the deposited film on the PFW were position-dependent and the extinction coefficient k 1 was about 1.0-2.0, which made the probing light not penetrate through some thick deposited films, the colorimetry method developed can only provide a rough value range of thickness of the metal-containing film deposited on the actual PFW in QUEST. However, the use of colorimetry is of great benefit to large-area inspections and to radioactive materials in future fusion devices that will be strictly prohibited from being taken out of the limited area.

  15. Nasal bone length, prenasal thickness, prenasal thickness-to-nasal bone length ratio and prefrontal space ratio in second- and third-trimester fetuses with Down syndrome.

    PubMed

    Vos, F I; De Jong-Pleij, E A P; Bakker, M; Tromp, E; Pajkrt, E; Kagan, K O; Bilardo, C M

    2015-02-01

    To evaluate nasal bone length (NBL), prenasal thickness (PT), prenasal thickness-to-nasal bone length (PT-NBL) ratio and prefrontal space ratio (PFSR) as markers for Down syndrome in the second and third trimesters. NBL, PT, PT-NBL ratio and PFSR were measured retrospectively in stored two-dimensional images or three-dimensional volumes (corrected to the mid-sagittal plane) of fetuses with Down syndrome, which were retrieved from the digital databases of participating units. Measurements were performed on the stored images and volumes by two experienced operators, and the values obtained were compared to our previously reported normal ranges for euploid fetuses in order to assess the detection rates for Down syndrome. A total of 159 fetuses with Down syndrome were included in the analysis, six of which were excluded because of inadequate available images. Median maternal age was 36.0 years and median gestational age was 23 + 1 weeks. NBL and PT were correlated with gestational age (P < 0.001), but the PT-NBL ratio and PFSR were not. Mean NBL, PT, PT-NBL ratio and PFSR were 4.42 mm, 5.56 mm, 1.26 and 0.34, respectively. The nasal bone was absent in 23 (15.4%) cases. As a marker for Down syndrome, the PT-NBL ratio yielded the highest detection rate (86.2%), followed by PFSR (79.7%), PT (63.4%) and NBL (61.9%). All markers were abnormal in 33.6% of cases, whilst all were normal in 4.7%. At least one of the four markers was abnormal in 95.3%, and either the PT-NBL ratio or PFSR was abnormal in 93.8%. Detection rates were not related to gestational age. The PT-NBL ratio and PFSR are robust second- and third-trimester markers for Down syndrome. Both provide high detection rates and are easy to use, as the cut-off for normality is constant throughout gestation. Ltd. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd.

  16. Ultrasonic guided wave tomography for wall thickness mapping in pipes

    NASA Astrophysics Data System (ADS)

    Willey, Carson L.

    Corrosion and erosion damage pose fundamental challenges to operation of oil and gas infrastructure. In order to manage the life of critical assets, plant operators must implement inspection programs aimed at assessing the severity of wall thickness loss (WTL) in pipelines, vessels, and other structures. Maximum defect depth determines the residual life of these structures and therefore represents one of the key parameters for robust damage mitigation strategies. In this context, continuous monitoring with permanently installed sensors has attracted significant interest and currently is the subject of extensive research worldwide. Among the different monitoring approaches being considered, significant promise is offered by the combination of guided ultrasonic wave technology with the principles of model based inversion under the paradigm of what is now referred to as guided wave tomography (GWT). Guided waves are attractive because they propagate inside the wall of a structure over a large distance. This can yield significant advantages over conventional pulse-echo thickness gage sensors that provide insufficient area coverage -- typically limited to the sensor footprint. While significant progress has been made in the application of GWT to plate-like structures, extension of these methods to pipes poses a number of fundamental challenges that have prevented the development of sensitive GWT methods. This thesis focuses on these challenges to address the complex guided wave propagation in pipes and to account for parametric uncertainties that are known to affect model based inversion and which are unavoidable in real field applications. The main contribution of this work is the first demonstration of a sensitive GWT method for accurately mapping the depth of defects in pipes. This is achieved by introducing a novel forward model that can extract information related to damage from the complex waveforms measured by pairs of guided wave transducers mounted on the pipe

  17. Enhanced washout of 99mTc-tetrofosmin in hypertrophic cardiomyopathy: quantitative comparisons with regional 123I-BMIPP uptake and wall thickness determined by MRI.

    PubMed

    Thet-Thet-Lwin; Takeda, Tohoru; Wu, Jin; Fumikura, Yuko; Iida, Keiji; Kawano, Satoru; Yamaguchi, Iwao; Itai, Yuji

    2003-07-01

    The diagnostic value of technetium-99m tetrofosmin (TF) washout in hypertrophic cardiomyopathy (HCM) was examined by investigating its relation to the metabolic abnormality depicted by iodine-123 beta-methyl- p-iodophenylpentadecanoic acid (BMIPP) uptake and the left ventricular (LV) myocardial wall thickness as measured by magnetic resonance imaging (MRI). TF washout was evaluated in 31 patients with HCM and 23 normal control subjects using 30-min (early) and 3-h (delayed) TF single-photon emission tomography images. The LV myocardial wall was divided into 19 segments and the percentage TF washout, regional BMIPP uptake and LV wall thickness were measured in each segment. Mean TF washout in the patients with HCM was significantly faster than that in normal control subjects (23.7+/-5.7 vs 13.4+/-4.1, P<0.0001). In the patients with HCM, TF washout showed an excellent correlation with MRI wall thickness ( r=0.82, P<0.0001) and a good inverse correlation with regional BMIPP uptake ( r=-0.72, P<0.0001). In addition, a good linear correlation was observed between TF uptake and MRI wall thickness in the 19 regional segments. In conclusion, the degree of TF washout corresponds well with the severity of myocardial wall thickness and the degree of metabolic abnormality in patients with HCM. These results suggest that enhanced TF washout might provide additional clinical information regarding metabolic alterations in HCM.

  18. A tale of two neglected systems-structure and function of the thin- and thick-walled sieve tubes in monocotyledonous leaves.

    PubMed

    Botha, C E J

    2013-01-01

    There is a large body of information relating to the ontogeny, development and the vasculature of eudicotyledonous leaves. However, there is less information available concerning the vascular anatomy of monocotyledonous leaves. This is surprising, given that there are two uniquely different phloem systems present in large groups such as grasses and sedges. Monocotyledonous leaves contain marginal, large, intermediate, and small longitudinal veins that are interconnected by numerous transverse veins. The longitudinal veins contain two metaphloem sieve tube types, which, based upon their ontogeny and position within the phloem, are termed early (thin-walled) and late (thick-walled) sieve tubes. Early metaphloem comprises sieve tubes, companion cells and vascular parenchyma (VP) cells, whilst the late metaphloem, contains thick-walled sieve tubes (TSTs) that lack companion cells. TSTs are generally adjacent to, or no more than one cell removed from the metaxylem. Unlike thin-walled sieve tube (ST) -companion cell complexes, TSTs are connected to parenchyma by pore-plasmodesma units and are generally symplasmically isolated from the STs. This paper addresses key structural and functional differences between thin- and thick-walled sieve tubes and explores the unique advantages of alternate transport strategies that this 5-7 million years old dual system may offer. It would seem that these two systems may enhance, add to, or play a significant role in increasing the efficiency of solute retrieval as well as of assimilate transfer.

  19. The effect of wall thickness distribution on mechanical reliability and strength in unidirectional porous ceramics.

    PubMed

    Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J

    2016-01-01

    Macroporous ceramics exhibit an intrinsic strength variability caused by the random distribution of defects in their structure. However, the precise role of microstructural features, other than pore volume, on reliability is still unknown. Here, we analyze the applicability of the Weibull analysis to unidirectional macroporous yttria-stabilized-zirconia (YSZ) prepared by ice-templating. First, we performed crush tests on samples with controlled microstructural features with the loading direction parallel to the porosity. The compressive strength data were fitted using two different fitting techniques, ordinary least squares and Bayesian Markov Chain Monte Carlo, to evaluate whether Weibull statistics are an adequate descriptor of the strength distribution. The statistical descriptors indicated that the strength data are well described by the Weibull statistical approach, for both fitting methods used. Furthermore, we assess the effect of different microstructural features (volume, size, densification of the walls, and morphology) on Weibull modulus and strength. We found that the key microstructural parameter controlling reliability is wall thickness. In contrast, pore volume is the main parameter controlling the strength. The highest Weibull modulus ([Formula: see text]) and mean strength (198.2 MPa) were obtained for the samples with the smallest and narrowest wall thickness distribution (3.1 [Formula: see text]m) and lower pore volume (54.5%).

  20. The effect of wall thickness distribution on mechanical reliability and strength in unidirectional porous ceramics

    NASA Astrophysics Data System (ADS)

    Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J.

    2016-01-01

    Macroporous ceramics exhibit an intrinsic strength variability caused by the random distribution of defects in their structure. However, the precise role of microstructural features, other than pore volume, on reliability is still unknown. Here, we analyze the applicability of the Weibull analysis to unidirectional macroporous yttria-stabilized-zirconia (YSZ) prepared by ice-templating. First, we performed crush tests on samples with controlled microstructural features with the loading direction parallel to the porosity. The compressive strength data were fitted using two different fitting techniques, ordinary least squares and Bayesian Markov Chain Monte Carlo, to evaluate whether Weibull statistics are an adequate descriptor of the strength distribution. The statistical descriptors indicated that the strength data are well described by the Weibull statistical approach, for both fitting methods used. Furthermore, we assess the effect of different microstructural features (volume, size, densification of the walls, and morphology) on Weibull modulus and strength. We found that the key microstructural parameter controlling reliability is wall thickness. In contrast, pore volume is the main parameter controlling the strength. The highest Weibull modulus (?) and mean strength (198.2 MPa) were obtained for the samples with the smallest and narrowest wall thickness distribution (3.1 ?m) and lower pore volume (54.5%).

  1. Airway wall thickness of allergic asthma caused by weed pollen or house dust mite assessed by computed tomography.

    PubMed

    Liu, Liping; Li, Guangrun; Sun, Yuemei; Li, Jian; Tang, Ningbo; Dong, Liang

    2015-03-01

    Little was known about Airway wall thickness of asthma patients with different allergen allergy. So we explored the possible difference of Airway wall thickness of asthma patients mono-sensitized to weed pollen or HDM using high-resolution computed tomography. 85 severe asthma patients were divided into weed pollen group and HDM group according to relevant allergen. 20 healthy donors served as controls. Airway wall area, percentage wall area and luminal area at the trunk of the apical bronchus of the right upper lobe were quantified using HRCT and compared. The values of pulmonary function were assessed as well. There were differences between HDM group and weed pollen group in WA/BSA,WA% and FEF25-75% pred, and no significant difference in FEV1%pred, FEV1/FVC and LA/BSA. In weed pollen group, WA/BSA was observed to correlate with the duration of rhinitis, whereas in HDM group, WA/BSA and LA/BSA was observed to correlate with the duration of asthma. In weed pollen group, FEV1/FVC showed a weak but significant negative correlation with WA%, but in HDM group FEV1/FVC showed a significant positive correlation with WA% and a statistical negative correlation with LA/BSA. FEV1/FVC and FEF25-75% pred were higher and WA/BSA and LA/BSA were lower in healthy control group than asthma group. FEV1%pred and WA% was no significant difference between asthma patients and healthy subjects. There are differences between HDM mono-sensitized subjects and weed pollen mono-sensitized subjects, not only in airway wall thickness, but also small airway obstruction. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Extremely thick cell walls and low mesophyll conductance: welcome to the world of ancient living!

    PubMed Central

    Tosens, Tiina; Laanisto, Lauri; Niinemets, Ülo

    2017-01-01

    Abstract Mesophyll conductance is thought to be an important photosynthetic limitation in gymnosperms, but they currently constitute the most understudied plant group in regard to the extent to which photosynthesis and intrinsic water use efficiency are limited by mesophyll conductance. A comprehensive analysis of leaf gas exchange, photosynthetic limitations, mesophyll conductance (calculated by three methods previously used for across-species comparisons), and the underlying ultra-anatomical, morphological and chemical traits in 11 gymnosperm species varying in evolutionary history was performed to gain insight into the evolution of structural and physiological controls on photosynthesis at the lower return end of the leaf economics spectrum. Two primitive herbaceous species were included in order to provide greater evolutionary context. Low mesophyll conductance was the main limiting factor of photosynthesis in the majority of species. The strongest sources of limitation were extremely thick mesophyll cell walls, high chloroplast thickness and variation in chloroplast shape and size, and the low exposed surface area of chloroplasts per unit leaf area. In gymnosperms, the negative relationship between net assimilation per mass and leaf mass per area reflected an increased mesophyll cell wall thickness, whereas the easy-to-measure integrative trait of leaf mass per area failed to predict the underlying ultrastructural traits limiting mesophyll conductance. PMID:28419340

  3. Impact of magnesium:calcium ratio on calcification of the aortic wall.

    PubMed

    Villa-Bellosta, Ricardo

    2017-01-01

    An inverse relationship between serum magnesium concentration and vascular calcification has been reported following observational clinical studies. Moreover, several studies have been suggesting a protective effect of magnesium on the vascular calcification. However, the exact mechanism remains elusive, and investigators have speculated among a myriad of potential actions. The effect of magnesium on calcification of the aortic wall is yet to be investigated. In the present study, the effects of magnesium and calcium on the metabolism of extracellular PPi, the main endogenous inhibitor of vascular calcification, were investigated in the rat aorta. Calcium and magnesium have antagonist effects on PPi hydrolysis in the aortic wall. Km and Ki values for PPi hydrolysis in rat aortic rings were 1.1 mmol/L magnesium and 32 μmol/L calcium, respectively, but ATP hydrolysis was not affected with calcium. Calcium deposition in the rat aortic wall dramatically increased when the magnesium concentration was increased (ratio of Mg:Ca = 1:1; 1.5 mmol/L calcium and 1.5 mmol/L magnesium) respect to low magnesium concentration (ratio Mg:Ca = 1:3, 1.5 mmol/L calcium and 0.75 mmol/L magnesium). Data from observational clinical studies showing that the serum magnesium concentration is inversely correlated with vascular calcification could be reinterpreted as a compensatory regulatory mechanism that reduces both PPi hydrolysis and vascular calcification. The impact of magnesium in vascular calcification in humans could be studied in association with calcium levels, for example, as the magnesium:calcium ratio.

  4. Stress-intensity factors for a thick-walled cylinder containing an annular imbedded or external or internal surface crack

    NASA Technical Reports Server (NTRS)

    Erdol, R.; Erdogan, F.

    1976-01-01

    The elastostatic axisymmetric problem for a long thick-walled cylinder containing a ring-shaped internal or edge crack is considered. Using the standard transform technique the problem is formulated in terms of an integral equation which has a simple Cauchy kernel for the internal crack and a generalized Cauchy kernel for the edge crack as the dominant part. As examples the uniform axial load and the steady-state thermal stress problems have been solved and the related stress intensity factors have been calculated. Among other findings the results show that in the cylinder under uniform axial stress containing an internal crack the stress intensity factor at the inner tip is always greater than that at the outer tip for equal net ligament thicknesses and in the cylinder with an edge crack which is under a state of thermal stress the stress intensity factor is a decreasing function of the crack depth, tending to zero as the crack depth approaches the wall thickness.

  5. High levels of thyroid-stimulating hormone are associated with aortic wall thickness in the general population.

    PubMed

    Ittermann, Till; Lorbeer, Roberto; Dörr, Marcus; Schneider, Tobias; Quadrat, Alexander; Heßelbarth, Lydia; Wenzel, Michael; Lehmphul, Ina; Köhrle, Josef; Mensel, Birger; Völzke, Henry

    2016-12-01

    Our aim was to investigate the association of thyroid function defined by serum concentrations of thyroid-stimulating hormone (TSH) with thoracic aortic wall thickness (AWT) as a marker of atherosclerotic processes. We pooled data of 2,679 individuals from two independent population-based surveys of the Study of Health in Pomerania. Aortic diameter and AWT measurements were performed on a 1.5-T MRI scanner at the concentration of the right pulmonary artery displaying the ascending and the descending aorta. TSH, treated as continuous variable, was significantly associated with descending AWT (β = 0.11; 95 % confidence interval (CI) 0.02-0.21), while the association with ascending AWT was not statistically significant (β = 0.20; 95 % CI -0.01-0.21). High TSH (>3.29 mIU/L) was significantly associated with ascending (β = 0.12; 95 % CI 0.02-0.23) but not with descending AWT (β = 0.06; 95 % CI -0.04-0.16). There was no consistent association between TSH and aortic diameters. Our study demonstrated that AWT values increase with increasing serum TSH concentrations. Thus, a hypothyroid state may be indicative for aortic atherosclerosis. These results fit very well to the findings of previous studies pointing towards increased atherosclerotic risk in the hypothyroid state. • Serum TSH concentrations are positively associated with aortic wall thickness. • Serum TSH concentrations are not associated with the aortic diameters. • Serum 3,5-diiodothyronine concentrations may be positively associated with aortic wall thickness.

  6. A tale of two neglected systems—structure and function of the thin- and thick-walled sieve tubes in monocotyledonous leaves

    PubMed Central

    Botha, C. E. J.

    2013-01-01

    There is a large body of information relating to the ontogeny, development and the vasculature of eudicotyledonous leaves. However, there is less information available concerning the vascular anatomy of monocotyledonous leaves. This is surprising, given that there are two uniquely different phloem systems present in large groups such as grasses and sedges. Monocotyledonous leaves contain marginal, large, intermediate, and small longitudinal veins that are interconnected by numerous transverse veins. The longitudinal veins contain two metaphloem sieve tube types, which, based upon their ontogeny and position within the phloem, are termed early (thin-walled) and late (thick-walled) sieve tubes. Early metaphloem comprises sieve tubes, companion cells and vascular parenchyma (VP) cells, whilst the late metaphloem, contains thick-walled sieve tubes (TSTs) that lack companion cells. TSTs are generally adjacent to, or no more than one cell removed from the metaxylem. Unlike thin-walled sieve tube (ST) -companion cell complexes, TSTs are connected to parenchyma by pore-plasmodesma units and are generally symplasmically isolated from the STs. This paper addresses key structural and functional differences between thin- and thick-walled sieve tubes and explores the unique advantages of alternate transport strategies that this 5–7 million years old dual system may offer. It would seem that these two systems may enhance, add to, or play a significant role in increasing the efficiency of solute retrieval as well as of assimilate transfer. PMID:23964280

  7. Fabrication of chitosan single-component microcapsules with a micrometer-thick and layered wall structure by stepwise core-mediated precipitation.

    PubMed

    Han, Yuanyuan; Tong, Weijun; Zhang, Yuying; Gao, Changyou

    2012-02-27

    Incubation of CaCO(3) microparticles in chitosan (CS) solution at pH 5.2 and following with ethylenediaminetetraacetic acid disodium salt (EDTA) treatment resulted in CS single-component microcapsules with an ultra-thick wall structure. Repeating the incubation caused stepwise increase of wall thickness and finally resulted in CS microcapsules with a layered structure. This unique method is mediated by precipitation of CS on the CaCO(3) particles as a result of pH increase caused by the partial dissolution of CaCO(3) . The obtained CS capsules are stable at neutral pH. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Steel Shear Walls, Behavior, Modeling and Design

    NASA Astrophysics Data System (ADS)

    Astaneh-Asl, Abolhassan

    2008-07-01

    In recent years steel shear walls have become one of the more efficient lateral load resisting systems in tall buildings. The basic steel shear wall system consists of a steel plate welded to boundary steel columns and boundary steel beams. In some cases the boundary columns have been concrete-filled steel tubes. Seismic behavior of steel shear wall systems during actual earthquakes and based on laboratory cyclic tests indicates that the systems are quite ductile and can be designed in an economical way to have sufficient stiffness, strength, ductility and energy dissipation capacity to resist seismic effects of strong earthquakes. This paper, after summarizing the past research, presents the results of two tests of an innovative steel shear wall system where the boundary elements are concrete-filled tubes. Then, a review of currently available analytical models of steel shear walls is provided with a discussion of capabilities and limitations of each model. We have observed that the tension only "strip model", forming the basis of the current AISC seismic design provisions for steel shear walls, is not capable of predicting the behavior of steel shear walls with length-to-thickness ratio less than about 600 which is the range most common in buildings. The main reasons for such shortcomings of the AISC seismic design provisions for steel shear walls is that it ignores the compression field in the shear walls, which can be significant in typical shear walls. The AISC method also is not capable of incorporating stresses in the shear wall due to overturning moments. A more rational seismic design procedure for design of shear walls proposed in 2000 by the author is summarized in the paper. The design method, based on procedures used for design of steel plate girders, takes into account both tension and compression stress fields and is applicable to all values of length-to-thickness ratios of steel shear walls. The method is also capable of including the effect of

  9. Impact of magnesium:calcium ratio on calcification of the aortic wall

    PubMed Central

    2017-01-01

    Objective An inverse relationship between serum magnesium concentration and vascular calcification has been reported following observational clinical studies. Moreover, several studies have been suggesting a protective effect of magnesium on the vascular calcification. However, the exact mechanism remains elusive, and investigators have speculated among a myriad of potential actions. The effect of magnesium on calcification of the aortic wall is yet to be investigated. In the present study, the effects of magnesium and calcium on the metabolism of extracellular PPi, the main endogenous inhibitor of vascular calcification, were investigated in the rat aorta. Approach and results Calcium and magnesium have antagonist effects on PPi hydrolysis in the aortic wall. Km and Ki values for PPi hydrolysis in rat aortic rings were 1.1 mmol/L magnesium and 32 μmol/L calcium, respectively, but ATP hydrolysis was not affected with calcium. Calcium deposition in the rat aortic wall dramatically increased when the magnesium concentration was increased (ratio of Mg:Ca = 1:1; 1.5 mmol/L calcium and 1.5 mmol/L magnesium) respect to low magnesium concentration (ratio Mg:Ca = 1:3, 1.5 mmol/L calcium and 0.75 mmol/L magnesium). Conclusion Data from observational clinical studies showing that the serum magnesium concentration is inversely correlated with vascular calcification could be reinterpreted as a compensatory regulatory mechanism that reduces both PPi hydrolysis and vascular calcification. The impact of magnesium in vascular calcification in humans could be studied in association with calcium levels, for example, as the magnesium:calcium ratio. PMID:28570619

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

    ERIC Educational Resources Information Center

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

    2009-01-01

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

  11. Ultrasound assessment of bladder wall thickness as a screening test for detrusor instability.

    PubMed

    Abou-Gamrah, Amgad; Fawzy, Mounir; Sammour, Hazem; Tadros, Sherif

    2014-05-01

    The aim of the current study was to evaluate the diagnostic accuracy of transvaginal ultrasound measurement of bladder wall thickness (BWT) in diagnosis of over active bladder (OAB). The current prospective study was conducted at Ain Shams University Maternity Hospital over 2 years. Patients presented to the urogynecology outpatient clinic with symptoms of urinary frequency, urgency, nocturia and/or urge incontinence were included in this study. The allocated patients were divided into two groups; Group 1(study group): fifty (50) patients with urodynamic diagnosis of detrusor instability (OAB) were included. Group 2 (control): fifty (50) patients with urodynamic diagnosis of stress incontinence were included. Using a transvaginal probe, BWT was measured in three sites at the thickest part of (a) the dome of the bladder (b) the trigone, and (c) the anterior wall of the bladder. An average of the three measurements was considered as the mean bladder thickness. A total of 100 patients with lower urinary symptoms were finally analyzed. There were no statistical significant differences between both groups regarding age, parity and body mass index, while there was statistically longer disease duration in group 2. Excluding urgency, there was statistical significant difference (P < 0.001) regarding lower urinary tract symptoms namely frequency, urgency incontinence, coital incontinence and nocturia. Patients in group 1 were more positive to symptoms of frequency, urgency incontinence, and nocturia, while patients in group 2 were more positive regarding coital incontinence. The thickness of trigon, dome, anterior wall and mean BWT was significantly higher in group 1 when compared to group 2. Receiver operator characteristics curve was constructed for estimating the association between mean BWT and prediction of OAB in patients with lower urinary tract symptoms. Mean BWT at 4.78 mm was considered as best cut-off value for prediction of OAB with sensitivity of 90 % and

  12. Collapse Pressure Analysis of Transversely Isotropic Thick-Walled Cylinder Using Lebesgue Strain Measure and Transition Theory

    PubMed Central

    Aggarwal, A. K.; Sharma, Richa; Sharma, Sanjeev

    2014-01-01

    The objective of this paper is to provide guidance for the design of the thick-walled cylinder made up of transversely isotropic material so that collapse of cylinder due to influence of internal and external pressure can be avoided. The concept of transition theory based on Lebesgue strain measure has been used to simplify the constitutive equations. Results have been analyzed theoretically and discussed numerically. From this analysis, it has been concluded that, under the influence of internal and external pressure, circular cylinder made up of transversely isotropic material (beryl) is on the safer side of the design as compared to the cylinders made up of isotropic material (steel). This is because of the reason that percentage increase in effective pressure required for initial yielding to become fully plastic is high for beryl as compared to steel which leads to the idea of “stress saving” that reduces the possibility of collapse of thick-walled cylinder due to internal and external pressure. PMID:24523632

  13. Ultrasonic thickness measuring and imaging system and method

    DOEpatents

    Bylenok, Paul J.; Patmos, William M.; Wagner, Thomas A.; Martin, Francis H.

    1992-08-04

    An ultrasonic thickness measuring and imaging system uses an ultrasonic fsed beam probe for measuring thickness of an object, such as a wall of a tube, a computer for controlling movement of the probe in a scanning pattern within the tube and processing an analog signal produced by the probe which is proportional to the tube wall thickness in the scanning pattern, and a line scan recorder for producing a record of the tube wall thicknesses measured by the probe in the scanning pattern. The probe is moved in the scanning pattern to sequentially scan circumferentially the interior tube wall at spaced apart adjacent axial locations. The computer processes the analog signal by converting it to a digital signal and then quantifies the digital signal into a multiplicity of thickness points with each falling in one of a plurality of thickness ranges corresponding to one of a plurality of shades of grey. From the multiplicity of quantified thickness points, a line scan recorder connected to the computer generates a pictorial map of tube wall thicknesses with each quantified thickness point thus being obtained from a minute area, e.g. 0.010 inch by 0.010 inch, of tube wall and representing one pixel of the pictorial map. In the pictorial map of tube wall thicknesses, the pixels represent different wall thicknesses having different shades of grey.

  14. Ultrasonic thickness measuring and imaging system and method

    DOEpatents

    Bylenok, Paul J.; Patmos, William M.; Wagner, Thomas A.; Martin, Francis H.

    1992-01-01

    An ultrasonic thickness measuring and imaging system uses an ultrasonic fsed beam probe for measuring thickness of an object, such as a wall of a tube, a computer for controlling movement of the probe in a scanning pattern within the tube and processing an analog signal produced by the probe which is proportional to the tube wall thickness in the scanning pattern, and a line scan recorder for producing a record of the tube wall thicknesses measured by the probe in the scanning pattern. The probe is moved in the scanning pattern to sequentially scan circumferentially the interior tube wall at spaced apart adjacent axial locations. The computer processes the analog signal by converting it to a digital signal and then quantifies the digital signal into a multiplicity of thickness points with each falling in one of a plurality of thickness ranges corresponding to one of a plurality of shades of grey. From the multiplicity of quantified thickness points, a line scan recorder connected to the computer generates a pictorial map of tube wall thicknesses with each quantified thickness point thus being obtained from a minute area, e.g. 0.010 inch by 0.010 inch, of tube wall and representing one pixel of the pictorial map. In the pictorial map of tube wall thicknesses, the pixels represent different wall thicknesses having different shades of grey.

  15. High Power Laser Beam Welding of Thick-walled Ferromagnetic Steels with Electromagnetic Weld Pool Support

    NASA Astrophysics Data System (ADS)

    Fritzsche, André; Avilov, Vjaceslav; Gumenyuk, Andrey; Hilgenberg, Kai; Rethmeier, Michael

    The development of modern high power laser systems allows single pass welding of thick-walled components with minimal distortion. Besides the high demands on the joint preparation, the hydrostatic pressure in the melt pool increases with higher plate thicknesses. Reaching or exceeding the Laplace pressure, drop-out or melt sagging are caused. A contactless electromagnetic weld support system was used for laser beam welding of thick ferromagnetic steel plates compensating these effects. An oscillating magnetic field induces eddy currents in the weld pool which generate Lorentz forces counteracting the gravity forces. Hysteresis effects of ferromagnetic steels are considered as well as the loss of magnetization in zones exceeding the Curie temperature. These phenomena reduce the effective Lorentz forces within the weld pool. The successful compensation of the hydrostatic pressure was demonstrated on up to 20 mm thick plates of duplex and mild steel by a variation of the electromagnetic power level and the oscillation frequency.

  16. Correlation of Gear Surface Fatigue Lives to Lambda Ratio (Specific Film Thickness)

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy Lewis

    2013-01-01

    The effect of the lubrication regime on gear performance has been recognized, qualitatively, for decades. Often the lubrication regime is characterized by the specific film thickness being the ratio of lubricant film thickness to the composite surface roughness. Three studies done at NASA to investigate gearing pitting life are revisited in this work. All tests were done at a common load. In one study, ground gears were tested using a variety of lubricants that included a range of viscosities, and therefore the gears operated with differing film thicknesses. In a second and third study, the performance of gears with ground teeth and superfinished teeth were assessed. Thicker oil films provided longer lives as did improved surface finish. These datasets were combined into a common dataset using the concept of specific film thickness. This unique dataset of more 258 tests provides gear designers with some qualitative information to make gear design decisions.

  17. Split thickness skin graft meshing ratio indications and common practices.

    PubMed

    Pripotnev, Stahs; Papp, Anthony

    2017-12-01

    Split thickness skin grafting is a commonly used technique in burn surgery for resurfacing wounds that are unlikely to heal without scarring. Meshing and expanding skin grafts allow for reconstruction of larger wounds with smaller donor sites. A retrospective chart review was performed of 210 patients with burns equal to or greater than 20% total body surface area admitted to Vancouver General Hospital between 1998 and 2014. Charts were reviewed to collect data on patient and burn demographics. A survey was sent to Canadian plastic surgeons registered with the CSPS to collect data on common practices in burn surgery nationwide. The patients that received 3:1 or higher meshed grafts were all flame burns, had a significantly higher average TBSA (51.89%±14.87 vs 29.13%±9.48, p=0.001), and a significantly higher full thickness burn TBSA (25.76%±21.97 vs 6.20%±9.04, p=0.001). We found no significant differences in gender, age, or burn location between the less than 2:1 and 3:1 or greater meshing ratio groups. The survey of plastic surgeons performing burn surgery in Canada revealed that 60% of responders had experience with skin grafts using meshing ratios of 3:1 or higher. Of these surgeons, 100% felt that burn size and 36% felt that burn location would influence their decision to use a 3:1 or higher meshing ratio. A larger burn size is the major influencing factor for the use of higher skin graft meshing ratios by Canadian burn surgeons. Furthermore, burn location determines the choice of donor and recipient sites in these cases. Copyright © 2017 Elsevier Ltd and ISBI. All rights reserved.

  18. Riser Difference Uncertainty Methodology Based on Tank AY-101 Wall Thickness Measurements with Application to Tank AN-107

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Weier, Dennis R.; Anderson, Kevin K.; Berman, Herbert S.

    2005-03-10

    The DST Integrity Plan (RPP-7574, 2003, Double-Shell Tank Integrity Program Plan, Rev. 1A, CH2M HILL Hanford Group, Inc., Richland, Washington.) requires the ultrasonic wall thickness measurement of two vertical scans of the tank primary wall while using a single riser location. The resulting measurements are then used in extreme value methodology to predict the minimum wall thickness expected for the entire tank. The representativeness of using a single riser in this manner to draw conclusions about the entire circumference of a tank has been questioned. The only data available with which to address the representativeness question comes from Tank AY-101more » since only for that tank have multiple risers been used for such inspection. The purpose of this report is to (1) further characterize AY-101 riser differences (relative to prior work); (2) propose a methodology for incorporating a ''riser difference'' uncertainty for subsequent tanks for which only a single riser is used, and (3) specifically apply the methodology to measurements made from a single riser in Tank AN-107.« less

  19. Ureteral wall thickness at the impacted ureteral stone site: a critical predictor for success rates after SWL.

    PubMed

    Sarica, Kemal; Kafkasli, Alper; Yazici, Özgür; Çetinel, Ali Cihangir; Demirkol, Mehmet Kutlu; Tuncer, Murat; Şahin, Cahit; Eryildirim, Bilal

    2015-02-01

    The aim of the study was to determine the possible predictive value of certain patient- and stone-related factors on the stone-free rates and auxiliary procedures after extracorporeal shock wave lithotripsy in patients with impacted proximal ureteral calculi. A total of 111 patients (86 male, 25 females M/F: 3.44/1) with impacted proximal ureteral stones treated with shock wave lithotripsy were evaluated. Cases were retrieved from a departmental shock wave lithotripsy database. Variables analyzed included BMI of the case, diameter of proximal ureter and renal pelvis, stone size and Hounsfield unit, ureteral wall thickness at the impacted stone site. Stone-free status on follow-up imaging at 3 months was considered a successful outcome. All patients had a single impacted proximal ureteral stone. While the mean age of the cases was 46 ± 13 years (range 26-79 years), mean stone size was 8.95 mm (5.3-15.1 mm). Following shock wave lithotripsy although 87 patients (78.4%) were completely stone-free at 3-month follow-up visit, 24 (21.6%) cases had residual fragments requiring further repeat procedures. Prediction of the final outcome of SWL in patients with impacted proximal ureteral stones is a challenging issue and our data did clearly indicate a highly significant relationship between ureteral wall thickness and the success rates of shock wave lithotripsy particularly in cases requiring additional procedures. Of all the evaluated stone- and patient-related factors, only ureteral wall thickness at the impacted stone site independently predicted shock wave lithotripsy success.

  20. Formation of Rhamnogalacturonan II-Borate Dimer in Pectin Determines Cell Wall Thickness of Pumpkin Tissue1

    PubMed Central

    Ishii, Tadashi; Matsunaga, Toshiro; Hayashi, Noriko

    2001-01-01

    Boron (B) deficiency results in inhibition of pumpkin (Cucurbia moschata Duchesne) growth that is accompanied by swelling of the cell walls. Monomeric rhamnogalacturonan II (mRG-II) accounted for 80% to 90% of the total RG-II in B-deficient walls, whereas the borate ester cross-linked RG-II dimer (dRG-II-B) accounted for more than 80% of the RG-II in control plants. The results of glycosyl residue and glycosyl linkage composition analyses of the RG-II from control and B-deficient plants were similar. Thus, B deficiency does not alter the primary structure of RG-II. The addition of 10B-enriched boric acid to B-deficient plants resulted within 5 h in the conversion of mRG-II to dRG-II-10B. The wall thickness of the 10B-treated plants and control plants was similar. The formation and possible functions of a borate ester cross-linked RG-II in the cell walls are discussed. PMID:11500567

  1. CMR assessment of the left ventricle apical morphology in subjects with unexplainable giant T-wave inversion and without apical wall thickness ≥15 mm.

    PubMed

    Wu, Bailin; Lu, Minjie; Zhang, Yan; Song, Bo; Ling, Jian; Huang, Jinghan; Yin, Gang; Lan, Tian; Dai, Linlin; Song, Lei; Jiang, Yong; Wang, Hao; He, Zuoxiang; Lee, Jongmin; Yong, Hwan Seok; Patel, Mehul B; Zhao, Shihua

    2017-02-01

    Patients with unexplainable giant T-wave inversion in the precordial leads and apical wall thickness <15 mm have been reported. These patients cannot be diagnosed as apical hypertrophic cardiomyopathy (AHCM) according to the current criteria. The objective of this study was to evaluate the apical morphological features of this type of patients using cardiac magnetic resonance. Institutional ethics approval and written informed consent were obtained. A total of 60 subjects with unexplainable giant T-wave inversion and 76 healthy volunteers were prospectively enrolled in the study. The segmented left ventricular (LV) wall thickness was measured according to the American Heart Association 17-segmented model. The apical angle (apA) as well as the regional variations in LV wall thickness was analysed. Considerable variation in LV wall thickness in normals was observed with progressive thinning from the base to apex (male and female, P < 0.01). The apical thickness of subjects with giant T-wave inversion was 8.10 ± 1.67 mm in male, which is thicker than that of controls (4.14 ± 1.17 mm, P < 0.01). In female, the apical thickness was also significantly different from controls (5.85 ± 2.16 vs. 2.99 ± 0.65 mm, P < 0.01). Compared with normals, the apA decreased significantly in male (87.44 ± 13.86 vs.115.03 ± 9.90°, P < 0.01) and female (90.69 ± 8.84 vs. 110.07 ± 13.58°, P < 0.01) subjects, respectively. Although the absolute thickness of apical wall was below the current diagnostic criteria of AHCM, the apical morphological features of subjects with unexplainable giant T-wave inversion were significantly different from normals. Whether these subjects should be included into a preclinical scope of AHCM needs further investigations. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

  2. Thickness-dependent domain wall reorientation in 70/30 lead magnesium niobate- lead titanate thin films

    DOE PAGES

    Keech, Ryan; Morandi, Carl; Wallace, Margeaux; ...

    2017-04-11

    Continued reduction in length scales associated with many ferroelectric film-based technologies is contingent on retaining the functional properties as the film thickness is reduced. Epitaxial and polycrystalline lead magnesium niobate - lead titanate (70PMN-30PT) thin films were studied over the thickness range of 100-350 nm for the relative contributions to property thickness dependence from interfacial and grain boundary low permittivity layers. Epitaxial PMN-PT films were grown on SrRuO 3 /(001)SrTiO 3, while polycrystalline films with {001}-Lotgering factors >0.96 were grown on Pt/TiO 2/SiO 2/Si substrates via chemical solution deposition. Both film types exhibited similar relative permittivities of ~300 at highmore » fields at all measured thicknesses with highly crystalline electrode/dielectric interfaces. These results, with the DC-biased and temperature dependent dielectric characterization, suggest irreversible domain wall mobility is the major contributor to the overall dielectric response and its thickness dependence. In epitaxial films, the irreversible Rayleigh coefficients reduced 85% upon decreasing thickness from 350 to 100 nm. The temperature at which a peak in the relative permittivity is observed was the only measured small signal quantity which was more thickness dependent in polycrystalline than epitaxial films. This is attributed to the relaxor nature present in the films, potentially stabilized by defect concentrations, and/or chemical inhomogeneity. Finally, the effective interfacial layers are found to contribute to the measured thickness dependence in the longitudinal piezoelectric coefficient.« less

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

    PubMed

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

    2016-02-01

    Giraffes--the tallest extant animals on Earth--are renowned for their high central arterial blood pressure, which is necessary to secure brain perfusion. Arterial pressure may exceed 300 mmHg and has historically been attributed to an exceptionally large heart. Recently, this has been refuted by several studies demonstrating that the mass of giraffe heart is similar to that of other mammals when expressed relative to body mass. It thus remains unexplained how the normal-sized giraffe heart generates such massive arterial pressures. We hypothesized that giraffe hearts have a small intraventricular cavity and a relatively thick ventricular wall, allowing for generation of high arterial pressures at normal left ventricular wall tension. In nine anaesthetized giraffes (495±38 kg), we determined in vivo ventricular dimensions using echocardiography along with intraventricular and aortic pressures to calculate left ventricular wall stress. Cardiac output was also determined by inert gas rebreathing to provide an additional and independent estimate of stroke volume. Echocardiography and inert gas-rebreathing yielded similar cardiac outputs of 16.1±2.5 and 16.4±1.4 l min(-1), respectively. End-diastolic and end-systolic volumes were 521±61 ml and 228±42 ml, respectively, yielding an ejection fraction of 56±4% and a stroke volume of 0.59 ml kg(-1). Left ventricular circumferential wall stress was 7.83±1.76 kPa. We conclude that, relative to body mass, a small left ventricular cavity and a low stroke volume characterizes the giraffe heart. The adaptations result in typical mammalian left ventricular wall tensions, but produce a lowered cardiac output. © 2016. Published by The Company of Biologists Ltd.

  4. Thinner regions of intracranial aneurysm wall correlate with regions of higher wall shear stress: a 7.0 tesla MRI

    PubMed Central

    Blankena, Roos; Kleinloog, Rachel; Verweij, Bon H.; van Ooij, Pim; ten Haken, Bennie; Luijten, Peter R.; Rinkel, Gabriel J.E.; Zwanenburg, Jaco J.M.

    2016-01-01

    Purpose To develop a method for semi-quantitative wall thickness assessment on in vivo 7.0 tesla (7T) MRI images of intracranial aneurysms for studying the relation between apparent aneurysm wall thickness and wall shear stress. Materials and Methods Wall thickness was analyzed in 11 unruptured aneurysms in 9 patients, who underwent 7T MRI with a TSE based vessel wall sequence (0.8 mm isotropic resolution). A custom analysis program determined the in vivo aneurysm wall intensities, which were normalized to signal of nearby brain tissue and were used as measure for apparent wall thickness (AWT). Spatial wall thickness variation was determined as the interquartile range in AWT (the middle 50% of the AWT range). Wall shear stress was determined using phase contrast MRI (0.5 mm isotropic resolution). We performed visual and statistical comparisons (Pearson’s correlation) to study the relation between wall thickness and wall shear stress. Results 3D colored AWT maps of the aneurysms showed spatial AWT variation, which ranged from 0.07 to 0.53, with a mean variation of 0.22 (a variation of 1.0 roughly means a wall thickness variation of one voxel (0.8mm)). In all aneurysms, AWT was inversely related to WSS (mean correlation coefficient −0.35, P<0.05). Conclusions A method was developed to measure the wall thickness semi-quantitatively, using 7T MRI. An inverse correlation between wall shear stress and AWT was determined. In future studies, this non-invasive method can be used to assess spatial wall thickness variation in relation to pathophysiologic processes such as aneurysm growth and –rupture. PMID:26892986

  5. Nonlinear fracture mechanics-based analysis of thin wall cylinders

    NASA Technical Reports Server (NTRS)

    Brust, Frederick W.; Leis, Brian N.; Forte, Thomas P.

    1994-01-01

    This paper presents a simple analysis technique to predict the crack initiation, growth, and rupture of large-radius, R, to thickness, t, ratio (thin wall) cylinders. The method is formulated to deal both with stable tearing as well as fatigue mechanisms in applications to both surface and through-wall axial cracks, including interacting surface cracks. The method can also account for time-dependent effects. Validation of the model is provided by comparisons of predictions to more than forty full scale experiments of thin wall cylinders pressurized to failure.

  6. Simulation of the development and interaction of instabilities in a relativistic electron beam under variation of the beam wall thickness

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Badarin, A. A.; Kurkin, S. A.; Koronovskii, A. A.

    The development and interaction of Bursian and diocotron instabilities in an annular relativistic electron beam propagating in a cylindrical drift chamber are investigated analytically and numerically as functions of the beam wall thickness and the magnitude of the external uniform magnetic field. It is found that the interaction of instabilities results in the formation of a virtual cathode with a complicated rotating helical structure and several reflection regions (electron bunches) in the azimuthal direction. It is shown that the number of electron bunches in the azimuthal direction increases with decreasing beam wall thickness and depends in a complicated manner onmore » the magnitude of the external magnetic field.« less

  7. [The effect of core veneer thickness ratio on the flexural strength of diatomite-based dental ceramic].

    PubMed

    Jiang, Jie; Zhang, Xin; Gao, Mei-qin; Zhang, Fei-min; Lu, Xiao-li

    2015-06-01

    To evaluate the effect of different core veneer thickness ratios on the flexural strength and failure mode of bilayered diatomite-based dental ceramics. Diatomite-based dental ceramics blocks (16 mm×5.4 mm×1 mm) were sintered with different thickness of veneer porcelains: 0 mm (group A), 0.6 mm (group B), 0.8 mm (group C) and 1.0 mm (group D). Flexural strength was detected and scanning electron microscope was used to observe the interface microstructure. Statistical analysis was performed using SPSS 17.0 software package. With the increase of the thickness of the veneer porcelain, flexural strength of group C showed highest flexural strength up to (277.24±5.47) MPa. Different core veneer thickness ratios can significantly influence the flexural strength of bilayered diatomite-based dental ceramics. Supported by Science and Technology Projects of Nantong City (HS2013010).

  8. Intracranial arterial wall imaging using three-dimensional high isotropic resolution black blood MRI at 3.0 Tesla.

    PubMed

    Qiao, Ye; Steinman, David A; Qin, Qin; Etesami, Maryam; Schär, Michael; Astor, Brad C; Wasserman, Bruce A

    2011-07-01

    To develop a high isotropic-resolution sequence to evaluate intracranial vessels at 3.0 Tesla (T). Thirteen healthy volunteers and 4 patients with intracranial stenosis were imaged at 3.0T using 0.5-mm isotropic-resolution three-dimensional (3D) Volumetric ISotropic TSE Acquisition (VISTA; TSE, turbo spin echo), with conventional 2D-TSE for comparison. VISTA was repeated for 6 volunteers and 4 patients at 0.4-mm isotropic-resolution to explore the trade-off between SNR and voxel volume. Wall signal-to-noise-ratio (SNR(wall) ), wall-lumen contrast-to-noise-ratio (CNR(wall-lumen) ), lumen area (LA), wall area (WA), mean wall thickness (MWT), and maximum wall thickness (maxWT) were compared between 3D-VISTA and 2D-TSE sequences, as well as 3D images acquired at both resolutions. Reliability was assessed by intraclass correlations (ICC). Compared with 2D-TSE measurements, 3D-VISTA provided 58% and 74% improvement in SNR(wall) and CNR(wall-lumen) , respectively. LA, WA, MWT and maxWT from 3D and 2D techniques highly correlated (ICCs of 0.96, 0.95, 0.96, and 0.91, respectively). CNR(wall-lumen) using 0.4-mm resolution VISTA decreased by 27%, compared with 0.5-mm VISTA but with reduced partial-volume-based overestimation of wall thickness. Reliability for 3D measurements was good to excellent. The 3D-VISTA provides SNR-efficient, highly reliable measurements of intracranial vessels at high isotropic-resolution, enabling broad coverage in a clinically acceptable time. Copyright © 2011 Wiley-Liss, Inc.

  9. The interaction of moderately strong shock waves with thick perforated walls of low porosity

    NASA Technical Reports Server (NTRS)

    Grant, D. J.

    1972-01-01

    A theoretical prediction is given of the flow through thick perforated walls of low porosity resulting from the impingement of a moderately strong traveling shock wave. The model was a flat plate positioned normal to the direction of the flow. Holes bored in the plate parallel to the direction of the flow provided nominal hole length-to-diameter ratios of 10:1 and an axial porosity of 25 percent of the flow channel cross section. The flow field behind the reflected shock wave was assumed to behave as a reservoir producing a quasi-steady duct flow through the model. Rayleigh and Fanno duct flow theoretical computations for each of three possible auxiliary wave patterns that can be associated with the transmitted shock (to satisfy contact surface compatibility) were used to provide bounding solutions as an alternative to the more complex influence coefficients method. Qualitative and quantitative behavior was verified in a 1.5- by 2.0-in. helium shock tube. High speed Schlieren photography, piezoelectric pressure-time histories, and electronic-counter wave speed measurements were used to assess the extent of correlation with the theoretical flow models. Reduced data indicated the adequacy of the bounding theory approach to predict wave phenomena and quantitative response.

  10. Determining the syringyl/guaiacyl lignin ratio in the vessel and fiber cell walls of transgenic Populus plants

    DOE PAGES

    Tolbert, Allison K.; Ma, Tao; Kalluri, Udaya C.; ...

    2016-06-20

    Observation of the spatial lignin distribution throughout the plant cell wall provides insight into the physicochemical characteristics of lignocellulosic biomass. The distribution of syringyl (S) and guaiacyl (G) lignin in cell walls of a genetically modified Populus deltoides and its corresponding empty vector control were analyzed with time-of-flight secondary ion mass spectrometry (ToF-SIMS) and then mapped to determine the S/G lignin ratio of the sample surface and specific regions of interest (ROIs). The surface characterizations of transgenic cross-sections within 1 cm vertical distance of each other on the stem possess similar S/G lignin ratios. Furthermore, the analysis of the ROIsmore » determined that there was a 50% decrease in the S/G lignin ratio of the transgenic xylem fiber cell walls.« less

  11. Determining the syringyl/guaiacyl lignin ratio in the vessel and fiber cell walls of transgenic Populus plants

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tolbert, Allison K.; Ma, Tao; Kalluri, Udaya C.

    Observation of the spatial lignin distribution throughout the plant cell wall provides insight into the physicochemical characteristics of lignocellulosic biomass. The distribution of syringyl (S) and guaiacyl (G) lignin in cell walls of a genetically modified Populus deltoides and its corresponding empty vector control were analyzed with time-of-flight secondary ion mass spectrometry (ToF-SIMS) and then mapped to determine the S/G lignin ratio of the sample surface and specific regions of interest (ROIs). The surface characterizations of transgenic cross-sections within 1 cm vertical distance of each other on the stem possess similar S/G lignin ratios. Furthermore, the analysis of the ROIsmore » determined that there was a 50% decrease in the S/G lignin ratio of the transgenic xylem fiber cell walls.« less

  12. Large-scale, thick, self-assembled, nacre-mimetic brick-walls as fire barrier coatings on textiles

    NASA Astrophysics Data System (ADS)

    Das, Paramita; Thomas, Helga; Moeller, Martin; Walther, Andreas

    2017-01-01

    Highly loaded polymer/clay nanocomposites with layered structures are emerging as robust fire retardant surface coatings. However, time-intensive sequential deposition processes, e.g. layer-by-layer strategies, hinders obtaining large coating thicknesses and complicates an implementation into existing technologies. Here, we demonstrate a single-step, water-borne approach to prepare thick, self-assembling, hybrid fire barrier coatings of sodium carboxymethyl cellulose (CMC)/montmorillonite (MTM) with well-defined, bioinspired brick-wall nanostructure, and showcase their application on textile. The coating thickness on the textile is tailored using different concentrations of CMC/MTM (1-5 wt%) in the coating bath. While lower concentrations impart conformal coatings of fibers, thicker continuous coatings are obtained on the textile surface from highest concentration. Comprehensive fire barrier and fire retardancy tests elucidate the increasing fire barrier and retardancy properties with increasing coating thickness. The materials are free of halogen and heavy metal atoms, and are sourced from sustainable and partly even renewable building blocks. We further introduce an amphiphobic surface modification on the coating to impart oil and water repellency, as well as self-cleaning features. Hence, our study presents a generic, environmentally friendly, scalable, and one-pot coating approach that can be introduced into existing technologies to prepare bioinspired, thick, fire barrier nanocomposite coatings on diverse surfaces.

  13. Finite element analysis of residual stress in cold expanded plate with different thickness and expansion ratio

    NASA Astrophysics Data System (ADS)

    Arifin Shariffudin, Kamarul; Karuppanan, Saravanan; Patil, Santosh S.

    2017-10-01

    Cold expansion of fastener/rivet holes is a common way to generate beneficial compressive residual stress around the fastener hole. In this study, cold expansion process was simulated by finite-element method in order to determine the residual stress field around two cold expanded holes by varying the plate thickness and expansion ratio of the hole. The model was developed in ANSYS and assigned to aluminium alloy 7475-T61 material model. The results showed that the residual stress become more compressive as the plate thickness is increased up to t/d = 2.6 and decreased for further level of thickness. In addition, the residual stress at the edge of the hole become more compressive as the expansion ratio is increased up to 4.5% and decreased for further level of expansion. This study also found that the residual stresses near the entrance and the exit face of the plate are less compressive than the residual stresses on the mid-thickness of the plate.

  14. Numerical Determination of Natural Frequencies and Modes of the Vibrations of a Thick-Walled Cylindrical Shell

    NASA Astrophysics Data System (ADS)

    Grigorenko, A. Ya.; Borisenko, M. Yu.; Boichuk, E. V.; Prigoda, A. P.

    2018-01-01

    The dynamic characteristics of a thick-walled cylindrical shell are determined numerically using the finite-element method implemented with licensed FEMAR software. The natural frequencies and modes are compared with those obtained earlier experimentally by the method of stroboscopic holographic interferometry. Frequency coefficients demonstrating how the natural frequency depends on the physical and mechanical parameters of the material are determined.

  15. Myocardial effective transverse relaxation time T2* Correlates with left ventricular wall thickness: A 7.0 T MRI study.

    PubMed

    Huelnhagen, Till; Hezel, Fabian; Serradas Duarte, Teresa; Pohlmann, Andreas; Oezerdem, Celal; Flemming, Bert; Seeliger, Erdmann; Prothmann, Marcel; Schulz-Menger, Jeanette; Niendorf, Thoralf

    2017-06-01

    Myocardial effective relaxation time T2* is commonly regarded as a surrogate for myocardial tissue oxygenation. However, it is legitimate to assume that there are multiple factors that influence T2*. To this end, this study investigates the relationship between T2* and cardiac macromorphology given by left ventricular (LV) wall thickness and left ventricular radius, and provides interpretation of the results in the physiological context. High spatio-temporally resolved myocardial CINE T2* mapping was performed in 10 healthy volunteers using a 7.0 Tesla (T) full-body MRI system. Ventricular septal wall thickness, left ventricular inner radius, and T2* were analyzed. Macroscopic magnetic field changes were elucidated using cardiac phase-resolved magnetic field maps. Ventricular septal T2* changes periodically over the cardiac cycle, increasing in systole and decreasing in diastole. Ventricular septal wall thickness and T2* showed a significant positive correlation, whereas the inner LV radius and T2* were negatively correlated. The effect of macroscopic magnetic field gradients on T2* can be considered minor in the ventricular septum. Our findings suggest that myocardial T2* is related to tissue blood volume fraction. Temporally resolved T2* mapping could be beneficial for myocardial tissue characterization and for understanding cardiac (patho)physiology in vivo. Magn Reson Med 77:2381-2389, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  16. Study by the Prandtl-Glauert method of compressibility effects and critical Mach number for ellipsoids of various aspect ratios and thickness ratios

    NASA Technical Reports Server (NTRS)

    Hess, Robert V; Gardner, Clifford S

    1947-01-01

    By using the Prandtl-Glauert method that is valid for three-dimensional flow problems, the value of the maximum incremental velocity for compressible flow about thin ellipsoids at zero angle of attack is calculated as a function of the Mach number for various aspect ratios and thickness ratios. The critical Mach numbers of the various ellipsoids are also determined. The results indicate an increase in critical Mach number with decrease in aspect ratio which is large enough to explain experimental results on low-aspect-ratio wings at zero lift.

  17. Optimum wall impedance for spinning modes: A correlation with mode cut-off ratio

    NASA Technical Reports Server (NTRS)

    Rice, E. J.

    1978-01-01

    A correlating equation relating the optimum acoustic impedance for the wall lining of a circular duct to the acoustic mode cut-off ratio, is presented. The optimum impedance was correlated with cut-off ratio because the cut-off ratio appears to be the fundamental parameter governing the propagation of sound in the duct. Modes with similar cut-off ratios respond in a similar way to the acoustic liner. The correlation is a semi-empirical expression developed from an empirical modification of an equation originally derived from sound propagation theory in a thin boundary layer. This correlating equation represents a part of a simplified liner design method, based upon modal cut-off ratio, for multimodal noise propagation.

  18. On the Opening of Thick Walled Elastic Tubes: A Fluid-Structure Model for Acid Reflux

    NASA Astrophysics Data System (ADS)

    Ghosh, Sudip; Kahrilas, Peter

    2005-11-01

    A coupled fluid-structure mathematical model was developed to quantify rapid opening of thick-walled elastic tubes, a phenomenon underlying biological flows such as gastroesophageal reflux disease (GERD). The wall was modeled using non-linear finite deformation theory to predict space-time radial distention of an axisymmetric tube with luminal fluid flow. Anisotropic azimuthal and longitudinal muscle-induced stresses were incorporated, and interstitial material properties were assumed isotropic and linearly elastic. Fluid flow was modeled using lubrication theory with inertial correction. Opening and flow were driven by a specified inflow pressure and zero pressure gradient was specified at outflow. No-slip and surface force balance were applied at the fluid-wall interface. Viscoelasticity was modeled with ad hoc damping and the evolution of the tube geometry was predicted at mid-layer. A potentially important discovery was made when applied to studies of initiation of opening with GERD: while material stiffness is of minor consequence, small changes in resting lumen distension (˜2 mm diameter) may be a sensitive distinguishing feature of the disease.

  19. Large-scale, thick, self-assembled, nacre-mimetic brick-walls as fire barrier coatings on textiles

    PubMed Central

    Das, Paramita; Thomas, Helga; Moeller, Martin; Walther, Andreas

    2017-01-01

    Highly loaded polymer/clay nanocomposites with layered structures are emerging as robust fire retardant surface coatings. However, time-intensive sequential deposition processes, e.g. layer-by-layer strategies, hinders obtaining large coating thicknesses and complicates an implementation into existing technologies. Here, we demonstrate a single-step, water-borne approach to prepare thick, self-assembling, hybrid fire barrier coatings of sodium carboxymethyl cellulose (CMC)/montmorillonite (MTM) with well-defined, bioinspired brick-wall nanostructure, and showcase their application on textile. The coating thickness on the textile is tailored using different concentrations of CMC/MTM (1–5 wt%) in the coating bath. While lower concentrations impart conformal coatings of fibers, thicker continuous coatings are obtained on the textile surface from highest concentration. Comprehensive fire barrier and fire retardancy tests elucidate the increasing fire barrier and retardancy properties with increasing coating thickness. The materials are free of halogen and heavy metal atoms, and are sourced from sustainable and partly even renewable building blocks. We further introduce an amphiphobic surface modification on the coating to impart oil and water repellency, as well as self-cleaning features. Hence, our study presents a generic, environmentally friendly, scalable, and one-pot coating approach that can be introduced into existing technologies to prepare bioinspired, thick, fire barrier nanocomposite coatings on diverse surfaces. PMID:28054589

  20. [Effect of core: dentin thickness ratio on the flexure strength of IPS Empress II heat-pressed all-ceramic restorative material].

    PubMed

    Liu, Yi-hong; Feng, Hai-lan; Bao, Yi-wang; Qiu, Yan

    2007-02-18

    To evaluate the effect of core:dentin thickness ratio on the flexure strength, fracture mode and origin of bilayered IPS Empress II ceramic composite specimens. IPS Empress II core ceramic, dentin porcelain and bilayered composite specimens with core:dentin thickness ratio of 2:1 and 1:1 were tested in three-point flexure strength. Mean strengths and standard deviations were determined. The optical microscopy was employed for identification of the fracture mode and origin. The flexure strength of dentin porcelain was the smallest(62.7 MPa), and the strength of bilayered composite specimens was smaller than single-layered core ceramic(190.2 MPa). The core: dentin ratio did not influence the strength of bilayered composite specimens. The frequency of occurrence of bilayered specimen delaminations was higher in the group of core: dentin thickness ratio of 1:1 than in the group of 2:1. IPS Empress II core ceramic was significantly stronger than veneering dentin porcelain. Core:dentin thickness ratio could significantly influence the fracture mode and origin, and bilayered IPS Empress II ceramic composite specimens showed little influence in the fracture strength.

  1. Strength Tests on Thin-walled Duralumin Cylinders in Torsion

    NASA Technical Reports Server (NTRS)

    Lundquist, Eugene E

    1932-01-01

    This report is the first of a series presenting the results of strength tests on thin-walled cylinders and truncated cones of circular and elliptical section; it comprises the results obtained to date from torsion (pure shear) tests on 65 thin-walled duralumin cylinders of circular section with ends clamped to rigid bulkheads. The effect of variations in the length/radius and radius/thickness ratios on the type of failure is indicated, and a semi-empirical equation for the shearing stress at maximum load is given.

  2. Huge domain-wall speed variation with respect to ferromagnetic layer thickness in ferromagnetic Pt/Co/TiO2/Pt films

    NASA Astrophysics Data System (ADS)

    Kim, Dae-Yun; Park, Min-Ho; Park, Yong-Keun; Yu, Ji-Sung; Kim, Joo-Sung; Kim, Duck-Ho; Min, Byoung-Chul; Choe, Sug-Bong

    2018-02-01

    In this study, we investigate the influence of the ferromagnetic layer thickness on the magnetization process. A series of ultrathin Pt/Co/TiO2/Pt films exhibits domain-wall (DW) speed variation of over 100,000 times even under the same magnetic field, depending on the ferromagnetic layer thickness. From the creep-scaling analysis, such significant variation is found to be mainly attributable to the thickness-dependence of the creep-scaling constant in accordance with the creep-scaling theory of the linear proportionality between the creep-scaling constant and the ferromagnetic layer thickness. Therefore, a thinner film shows a faster DW speed. The DW roughness also exhibits sensitive dependence on the ferromagnetic layer thickness: a thinner film shows smoother DW. The present observation provided a guide for an optimal design rule of the ferromagnetic layer thickness for better performance of DW-based devices.

  3. Validity of the temporal-to-nasal macular ganglion cell-inner plexiform layer thickness ratio as a diagnostic parameter in early glaucoma.

    PubMed

    Park, Jung-Won; Jung, Hyun-Ho; Heo, Hwan; Park, Sang-Woo

    2015-08-01

    To evaluate the diagnostic validity of temporal-to-nasal macular ganglion cell-inner plexiform layer thickness (TNM) ratio using Cirrus high definition-optical coherence tomography (HD-OCT) in patients with early glaucomatous damage. Enrolled participants included 130 normal controls, 50 patients with preperimetric glaucoma and 106 patients with early glaucoma. The patients with early glaucoma were classified into two subgroups according to the pattern of the visual field (VF) defects: the paracentral scotoma (PCS, n = 54) and the peripheral scotoma (PPS, n = 52). The thickness of the macular ganglion cell-inner plexiform layer (mGCIPL) and circumpapillary retinal nerve fibre layer (cpRNFL) was measured by Cirrus HD-OCT, and the average, superior and inferior TNM ratio was calculated. The average TNM ratio is a sum of superotemporal and inferotemporal mGCIPL thicknesses divided by the sum of superonasal and inferonasal mGCIPL thicknesses. Area under the receiver operating characteristic curve (AROC) of each parameter was compared between the groups. The parameter with the best AROC was the average TNM ratio and inferotemporal mGCIPL thickness in the PCS group and average cpRNFL thickness in the PPS group. The AROCs of the average, superior and inferior TNM ratio (p < 0.001, p = 0.007 and p < 0.001, respectively), minimum, average, inferotemporal and inferior mGCIPL thickness (p = 0.004, p = 0.003, p = 0.002 and p = 0.001, respectively) of the PCS were significantly higher than those of the PPS. However, the AROCs of the all cpRNFL thickness parameters did not show statistically significant differences between two subgroups. Asymmetry of temporal-to-nasal mGCIPL thickness could be an important parameter in the diagnosis of early glaucoma with paracentral VF defects. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  4. Sex, race, and age distributions of mean aortic wall thickness in a multiethnic population-based sample.

    PubMed

    Rosero, Eric B; Peshock, Ronald M; Khera, Amit; Clagett, Patrick; Lo, Hao; Timaran, Carlos H

    2011-04-01

    Reference values and age-related changes of the wall thickness of the abdominal aorta have not been described in the general population. We characterized age-, race-, and gender-specific distributions, and yearly rates of change of mean aortic wall thickness (MAWT), and associations between MAWT and cardiovascular risk factors in a multi-ethnic population-based probability sample. Magnetic resonance imaging measurements of MAWT were performed on 2466 free-living white, black, and Hispanic adult subjects. MAWT race/ethnicity- and gender-specific percentile values across age were estimated using regression analyses. MAWT was greater in men than in women and increased linearly with age in all the groups and across all the percentiles. Hispanic women had the thinnest and black men the thickest aortas. Black men had the highest and white women the lowest age-related MAWT increase. Age, gender, ethnicity, smoking status, systolic blood pressure, low-density lipoprotein-cholesterol levels, high-density lipoprotein-cholesterol levels, and fasting glucose levels were independent predictors of MAWT. Age, gender, and racial/ethnic differences in MAWT distributions exist in the general population. Such differences should be considered in future investigations assessing aortic atherosclerosis and the effects of anti-atherosclerotic therapies. Published by Mosby, Inc.

  5. The ratio of microwaves to X-rays in solar flares: The case for the thick target model

    NASA Technical Reports Server (NTRS)

    Lu, Edward T.; Petrosian, Vahe

    1988-01-01

    The expected ratio of synchrotron microwave radiation to bremsstrahlung X-rays for thick target, thin target, and multithermal solar flare models is calculated. The calculations take into account the variation of the microwave to X-ray ratio with X-ray spectral index. The theoretical results are compared with observed ratios of a sample of 51 solar flares with well known spectral index. From this it is concluded that the nonthermal thick target model with a loop length of and order of 10 to the 9th power cm and a magnetic field of 500 + or - 200 G provides the best fit to the data. The thin target and multithermal models require unreasonably large density or pressure and/or low magnetic field to match the data.

  6. Ultrasonographic evaluation of myometrial thickness and prediction of a successful external cephalic version.

    PubMed

    Buhimschi, Catalin S; Buhimschi, Irina A; Wehrum, Mark J; Molaskey-Jones, Sherry; Sfakianaki, Anna K; Pettker, Christian M; Thung, Stephen; Campbell, Katherine H; Dulay, Antonette T; Funai, Edmund F; Bahtiyar, Mert O

    2011-10-01

    To test the hypothesis that myometrial thickness predicts the success of external cephalic version. Abdominal ultrasonographic scans were performed in 114 consecutive pregnant women with breech singletons before an external cephalic version maneuver. Myometrial thickness was measured by a standardized protocol at three sites: the lower segment, midanterior wall, and the fundal uterine wall. Independent variables analyzed in conjunction with myometrial thickness were: maternal age, parity, body mass index, abdominal wall thickness, estimated fetal weight, amniotic fluid index, placental thickness and location, fetal spine position, breech type, and delivery outcomes such as final mode of delivery and birth weight. Successful version was associated with a thicker ultrasonographic fundal myometrium (unsuccessful: 6.7 [5.5-8.4] compared with successful: 7.4 [6.6-9.7] mm, P=.037). Multivariate regression analysis showed that increased fundal myometrial thickness, high amniotic fluid index, and nonfrank breech presentation were the strongest independent predictors of external cephalic version success (P<.001). A fundal myometrial thickness greater than 6.75 mm and an amniotic fluid index greater than 12 cm were each associated with successful external cephalic versions (fundal myometrial thickness: odds ratio [OR] 2.4, 95% confidence interval [CI] 1.1-5.2, P=.029; amniotic fluid index: OR 2.8, 95% CI 1.3-6.0, P=.008). Combining the two variables resulted in an absolute risk reduction for a failed version of 27.6% (95% CI 7.1-48.1) and a number needed to treat of four (95% CI 2.1-14.2). Fundal myometrial thickness and amniotic fluid index contribute to success of external cephalic version and their evaluation can be easily incorporated in algorithms before the procedure. III.

  7. Noninvasive detection of coronary artery wall thickening with age in healthy subjects using high resolution MRI with beat-to-beat respiratory motion correction.

    PubMed

    Scott, Andrew D; Keegan, Jennifer; Mohiaddin, Raad H; Firmin, David N

    2011-10-01

    To demonstrate coronary artery wall thickening with age in a small healthy cohort using a highly efficient, reliable, and reproducible high-resolution MR technique. A 3D cross-sectional MR vessel wall images (0.7 × 0.7 × 3 mm resolution) with retrospective beat-to-beat respiratory motion correction (B2B-RMC) were obtained in the proximal right coronary artery of 21 healthy subjects (age, 22-62 years) with no known cardiovascular disease. Lumen and outer wall (lumen + vessel wall) areas were measured in one central slice from each subject and average wall thickness and wall area/outer wall area ratio (W/OW) calculated. Imaging was successful in 18 (86%) subjects with average respiratory efficiency 99.3 ± 1.7%. Coronary vessel wall thickness and W/OW significantly correlate with subject age, increasing by 0.088 mm and 0.031 per decade respectively (R = 0.53, P = 0.024 and R = 0.48, P = 0.046). No relationship was found between lumen area and vessel wall thickness (P = NS), but outer wall area increased significantly with vessel wall thickness at 19 mm(2) per mm (P = 0.046). This is consistent with outward vessel wall remodeling. Despite the small size of our healthy cohort, using high-resolution MR imaging and B2B-RMC, we have demonstrated increasing coronary vessel wall thickness and W/OW with age. The results obtained are consistent with outward vessel wall remodeling. Copyright © 2011 Wiley-Liss, Inc.

  8. Wall-to-lumen ratio of intracranial arteries measured by indocyanine green angiography

    PubMed Central

    Nakagawa, Daichi; Shojima, Masaaki; Yoshino, Masanori; Kin, Taichi; Imai, Hideaki; Nomura, Seiji; Saito, Toki; Nakatomi, Hirofumi; Oyama, Hiroshi; Saito, Nobuhito

    2016-01-01

    Background: The wall-to-lumen ratio (WLR) is an important parameter in vascular medicine because it indicates the character of vascular wall as well as the degree of stenosis. Despite the advances in medical imaging technologies, it is still difficult to measure the thin-walled normal intracranial arteries, and the reports on the WLR of normal intracranial artery are limited. It might be possible to calculate the WLR using the indocyanine green (ICG) angiography, which is used to observe intracranial vessels during microsurgery. Purpose: To evaluate the WLR of normal intracranial arteries using ICG angiography. Materials and Methods: From the three cases in which ICG angiography was recorded with a ruler during microsurgery, 20 measurement points were chosen for the analysis. The ICG was injected intravenously with a dose of 0.2 mg/kg, and the vessels were inspected at high magnification using an operating microscope equipped with near-infrared illumination system. The vessel outer diameter and the luminal diameter were measured using the images before and after the ICG arrival based on the pixel ratio method using a ruler as reference, respectively. The WLR was calculated as 0.5 × (vessel outer diameter − vessel luminal diameter). Results: The WLR (mean ± standard deviation) of normal intracranial arteries was 0.086 ± 0.022. The WLR tended to be high in small arteries. Conclusion: The WLR of normal intracranial arteries calculated using ICG angiography was consistent with the WLR reported in the previous reports based on human autopsy. PMID:27695538

  9. A hybrid method for airway segmentation and automated measurement of bronchial wall thickness on CT.

    PubMed

    Xu, Ziyue; Bagci, Ulas; Foster, Brent; Mansoor, Awais; Udupa, Jayaram K; Mollura, Daniel J

    2015-08-01

    Inflammatory and infectious lung diseases commonly involve bronchial airway structures and morphology, and these abnormalities are often analyzed non-invasively through high resolution computed tomography (CT) scans. Assessing airway wall surfaces and the lumen are of great importance for diagnosing pulmonary diseases. However, obtaining high accuracy from a complete 3-D airway tree structure can be quite challenging. The airway tree structure has spiculated shapes with multiple branches and bifurcation points as opposed to solid single organ or tumor segmentation tasks in other applications, hence, it is complex for manual segmentation as compared with other tasks. For computerized methods, a fundamental challenge in airway tree segmentation is the highly variable intensity levels in the lumen area, which often causes a segmentation method to leak into adjacent lung parenchyma through blurred airway walls or soft boundaries. Moreover, outer wall definition can be difficult due to similar intensities of the airway walls and nearby structures such as vessels. In this paper, we propose a computational framework to accurately quantify airways through (i) a novel hybrid approach for precise segmentation of the lumen, and (ii) two novel methods (a spatially constrained Markov random walk method (pseudo 3-D) and a relative fuzzy connectedness method (3-D)) to estimate the airway wall thickness. We evaluate the performance of our proposed methods in comparison with mostly used algorithms using human chest CT images. Our results demonstrate that, on publicly available data sets and using standard evaluation criteria, the proposed airway segmentation method is accurate and efficient as compared with the state-of-the-art methods, and the airway wall estimation algorithms identified the inner and outer airway surfaces more accurately than the most widely applied methods, namely full width at half maximum and phase congruency. Copyright © 2015. Published by Elsevier B.V.

  10. Microwave background distortions from domain walls

    NASA Technical Reports Server (NTRS)

    Goetz, Guenter; Noetzold, Dirk

    1990-01-01

    Domain walls arising in a cosmic phase transition after decoupling were recently proposed as seeds for the formation of large scale structure. The distortion induced in the microwave background radiation is calculated in dependence of the wall thickness, surface density, scalar field potential, cosmic redshift and the velocity of the wall. It was found that the maximal redshift distortion for both spherical and planar walls is of the order pi G sigma H(sup -1)(sub 0), where sigma is the surface energy density and H(sup -1)(sub 0) the Hubble parameter. It was also found that, for a wall thickness smaller than the horizon, walls can be treated as infinitely thin, i.e., the redshift distortion is independent of the wall thickness and the specific form of the scalar potential. For planar walls moving with a Lorentz-factor gamma the redshift distortion is enhanced by gamma cubed.

  11. Experimental, numerical, and analytical studies on the seismic response of steel-plate concrete (SC) composite shear walls

    NASA Astrophysics Data System (ADS)

    Epackachi, Siamak

    The seismic performance of rectangular steel-plate concrete (SC) composite shear walls is assessed for application to buildings and mission-critical infrastructure. The SC walls considered in this study were composed of two steel faceplates and infill concrete. The steel faceplates were connected together and to the infill concrete using tie rods and headed studs, respectively. The research focused on the in-plane behavior of flexure- and flexure-shear-critical SC walls. An experimental program was executed in the NEES laboratory at the University at Buffalo and was followed by numerical and analytical studies. In the experimental program, four large-size specimens were tested under displacement-controlled cyclic loading. The design variables considered in the testing program included wall thickness, reinforcement ratio, and slenderness ratio. The aspect ratio (height-to-length) of the four walls was 1.0. Each SC wall was installed on top of a re-usable foundation block. A bolted baseplate to RC foundation connection was used for all four walls. The walls were identified to be flexure- and flexure-shear critical. The progression of damage in the four walls was identical, namely, cracking and crushing of the infill concrete at the toes of the walls, outward buckling and yielding of the steel faceplates near the base of the wall, and tearing of the faceplates at their junctions with the baseplate. A robust finite element model was developed in LS-DYNA for nonlinear cyclic analysis of the flexure- and flexure-shear-critical SC walls. The DYNA model was validated using the results of the cyclic tests of the four SC walls. The validated and benchmarked models were then used to conduct a parametric study, which investigated the effects of wall aspect ratio, reinforcement ratio, wall thickness, and uniaxial concrete compressive strength on the in-plane response of SC walls. Simplified analytical models, suitable for preliminary analysis and design of SC walls, were

  12. Method and apparatus to produce and maintain a thick, flowing, liquid lithium first wall for toroidal magnetic confinement DT fusion reactors

    DOEpatents

    Woolley, Robert D.

    2002-01-01

    A system for forming a thick flowing liquid metal, in this case lithium, layer on the inside wall of a toroid containing the plasma of a deuterium-tritium fusion reactor. The presence of the liquid metal layer or first wall serves to prevent neutron damage to the walls of the toroid. A poloidal current in the liquid metal layer is oriented so that it flows in the same direction as the current in a series of external magnets used to confine the plasma. This current alignment results in the liquid metal being forced against the wall of the toroid. After the liquid metal exits the toroid it is pumped to a heat extraction and power conversion device prior to being reentering the toroid.

  13. Dielectric and Piezoelectric Properties of PZT Composite Thick Films with Variable Solution to Powder Ratios.

    PubMed

    Wu, Dawei; Zhou, Qifa; Shung, Koping Kirk; Bharadwaja, Srowthi N; Zhang, Dongshe; Zheng, Haixing

    2009-05-08

    The use of PZT films in sliver-mode high-frequency ultrasonic transducers applications requires thick, dense, and crack-free films with excellent piezoelectric and dielectric properties. In this work, PZT composite solutions were used to deposit PZT films >10 μm in thickness. It was found that the functional properties depend strongly on the mass ratio of PZT sol-gel solution to PZT powder in the composite solution. Both the remanent polarization, P(r), and transverse piezoelectric coefficient, e(31,) (f), increase with increasing proportion of the sol-gel solution in the precursor. Films prepared using a solution-to-powder mass ratio of 0.5 have a remanent polarization of 8 μC/cm(2), a dielectric constant of 450 (at 1 kHz), and e(31,) (f) = -2.8 C/m(2). Increasing the solution-to-powder mass ratio to 6, the films were found to have remanent polarizations as large as 37 μC/cm(2), a dielectric constant of 1250 (at 1 kHz) and e(31,) (f) = -5.8 C/m(2).

  14. Correlation between central corneal thickness and visual field defects, cup to disc ratio and retinal nerve fiber layer thickness in primary open angle glaucoma patients.

    PubMed

    Sarfraz, Muhammad Haroon; Mehboob, Mohammad Asim; Haq, Rana Intisar Ul

    2017-01-01

    To evaluate the correlation between Central Corneal Thickness (CCT) and Visual Field (VF) defect parameters like Mean Deviation (MD) and Pattern Standard Deviation (PSD), Cup-to-Disc Ratio (CDR) and Retinal Nerve Fibre Layer Thickness (RNFL-T) in Primary Open-Angle Glaucoma (POAG) patients. This cross sectional study was conducted at Armed Forces Institute of Ophthalmology (AFIO), Rawalpindi from September 2015 to September 2016. Sixty eyes of 30 patients with diagnosed POAG were analysed. Correlation of CCT with other variables was studied. Mean age of study population was 43.13±7.54 years. Out of 30 patients, 19 (63.33%) were males and 11 (36.67%) were females. Mean CCT, MD, PSD, CDR and RNFL-T of study population was 528.57±25.47µm, -9.11±3.07, 6.93±2.73, 0.63±0.13 and 77.79±10.44µm respectively. There was significant correlation of CCT with MD, PSD and CDR (r=-0.52, p<0.001; r=-0.59, p<0.001;r=-0.41, p=0.001 respectively). The correlation of CCT with RNFL-T was not statistically significant (r=-0.14, p=0.284). Central corneal thickness had significant correlation with visual field parameters like mean deviation and pattern standard deviation, as well as with cup-to-disc ratio. However, central corneal thickness had no significant relationship with retinal nerve fibre layer thickness.

  15. Fast mean and variance computation of the diffuse sound transmission through finite-sized thick and layered wall and floor systems

    NASA Astrophysics Data System (ADS)

    Decraene, Carolina; Dijckmans, Arne; Reynders, Edwin P. B.

    2018-05-01

    A method is developed for computing the mean and variance of the diffuse field sound transmission loss of finite-sized layered wall and floor systems that consist of solid, fluid and/or poroelastic layers. This is achieved by coupling a transfer matrix model of the wall or floor to statistical energy analysis subsystem models of the adjacent room volumes. The modal behavior of the wall is approximately accounted for by projecting the wall displacement onto a set of sinusoidal lateral basis functions. This hybrid modal transfer matrix-statistical energy analysis method is validated on multiple wall systems: a thin steel plate, a polymethyl methacrylate panel, a thick brick wall, a sandwich panel, a double-leaf wall with poro-elastic material in the cavity, and a double glazing. The predictions are compared with experimental data and with results obtained using alternative prediction methods such as the transfer matrix method with spatial windowing, the hybrid wave based-transfer matrix method, and the hybrid finite element-statistical energy analysis method. These comparisons confirm the prediction accuracy of the proposed method and the computational efficiency against the conventional hybrid finite element-statistical energy analysis method.

  16. SU-E-T-571: Prostate IMRT QA: Prediction of the Range of Rectal NTCP Using a 2D Field Approach Based on Variations of the Rectal Wall Motion and Thickness.

    PubMed

    Grigorov, G; Chow, J; Foster, K

    2012-06-01

    The aims of this study is to (1) introduce a 2D field of possible rectal normal tissue complication probability (NTCP) in prostate intensity modulated radiotherapy (IMRT) plan, so that based on a given prescribed dose the rectal NTCP is merely a function of the rectal wall thickness and rectal motion; and (2) separate the 2D field of rectal NTCP into area of low risk and area of high risk for rectal toxicity < Grade II, based on the threshold rectal NTCP. The 2D field of NTCP model was developed using ten randomly selected prostate IMRT plans. The clinical rectal geometry was initially represented by the cylindrical contour in the treatment planning system. Different combinations of rectal motions, rectal wall thicknesses, planning target volume margins and prescribed doses were used to determine the NTCP in prostate IMRT plans. It was found that the functions bordering the 2D field for the given AP, LR and SI direction can be described as exponential, quadratic and linear equations, respectively. A ratio of the area of 2D field containing data of the low risk NTCP to the entire area of the field was introduced and calculated. Although our method is based on the Kutcher's dose response model and published tissue parameters, other mathematical models can be used in our approach. The 2D field of rectal NTCP is useful to estimate the rectal NTCP range in the prostate pre-treatment and treatment QA. Our method can determine the patient's threshold immobilization for a given rectal wall thickness so that prescribed dose can be delivered to the prostate to avoid rectal complication. Our method is also applicable to multi-phase prostate IMRT, and can be adapted to any treatment planning systems. © 2012 American Association of Physicists in Medicine.

  17. 49 CFR 179.400-8 - Thickness of plates.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400-8 Thickness of plates... joints, except that for seamless heads, E = 1.0. (b) The minimum wall thickness, after forming, of any 3..., except that for seamless heads, E=1.0. (c) The minimum wall thickness, after forming, of a flanged and...

  18. 49 CFR 179.400-8 - Thickness of plates.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400-8 Thickness of plates... joints, except that for seamless heads, E = 1.0. (b) The minimum wall thickness, after forming, of any 3..., except that for seamless heads, E=1.0. (c) The minimum wall thickness, after forming, of a flanged and...

  19. 49 CFR 179.400-8 - Thickness of plates.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400-8 Thickness of plates... joints, except that for seamless heads, E = 1.0. (b) The minimum wall thickness, after forming, of any 3..., except that for seamless heads, E=1.0. (c) The minimum wall thickness, after forming, of a flanged and...

  20. 49 CFR 179.400-8 - Thickness of plates.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400-8 Thickness of plates... joints, except that for seamless heads, E = 1.0. (b) The minimum wall thickness, after forming, of any 3..., except that for seamless heads, E=1.0. (c) The minimum wall thickness, after forming, of a flanged and...

  1. Agreement between methods of measurement of mean aortic wall thickness by MRI.

    PubMed

    Rosero, Eric B; Peshock, Ronald M; Khera, Amit; Clagett, G Patrick; Lo, Hao; Timaran, Carlos

    2009-03-01

    To assess the agreement between three methods of calculation of mean aortic wall thickness (MAWT) using magnetic resonance imaging (MRI). High-resolution MRI of the infrarenal abdominal aorta was performed on 70 subjects with a history of coronary artery disease who were part of a multi-ethnic population-based sample. MAWT was calculated as the mean distance between the adventitial and luminal aortic boundaries using three different methods: average distance at four standard positions (AWT-4P), average distance at 100 automated positions (AWT-100P), and using a mathematical computation derived from the total vessel and luminal areas (AWT-VA). Bland-Altman plots and Passing-Bablok regression analyses were used to assess agreement between methods. Bland-Altman analyses demonstrated a positive bias of 3.02+/-7.31% between the AWT-VA and the AWT-4P methods, and of 1.76+/-6.82% between the AWT-100P and the AWT-4P methods. Passing-Bablok regression analyses demonstrated constant bias between the AWT-4P method and the other two methods. Proportional bias was, however, not evident among the three methods. MRI methods of measurement of MAWT using a limited number of positions of the aortic wall systematically underestimate the MAWT value compared with the method that calculates MAWT from the vessel areas. Copyright (c) 2009 Wiley-Liss, Inc.

  2. Frontonasal fold thickness-to-nasal bone length ratio as a prenatal sonographic marker for trisomy 21 in a low-risk population.

    PubMed

    Gonzalez, Ruben; Aedo, Socrates; Dezerega, Victor; Sepulveda, Waldo

    2013-05-01

    To report normative data for the fetal nasal bone length (NBL), frontonasal fold (FNF) thickness, and the FNF/NBL ratio and to study their performance in the sonographic screening of trisomy 21 in a normal, unselected Latin American population. Women undergoing a routine sonographic examination between 16 and 32 weeks' gestation at a primary health care center in Santiago, Chile, were prospectively recruited for NBL and FNF thickness measurements. Pregnancies with maternal/fetal complications were subsequently excluded from analysis. Correlations between NBL, FNF thickness, and FNF/NBL ratio and gestational age were assessed with the Spearman correlation coefficient (ρ). To generate reference percentiles for NBL and FNF thickness, adjusted regression models were derived using a statistical method for calculating reference percentiles of fetal biometric parameters. A total of 1922 cases complied with entry criteria. Both the NBL and the FNF thickness increased with gestational age. However, the FNF/NBL ratio remained constant (ρ= 0.016; P = .95), with a mean value of 0.68 and 95th and 99th percentile values of 0.84 and 0.90, respectively. During the study period, all 4 fetuses with trisomy 21 diagnosed in this low-risk population had an FNF/NBL ratio above the 99th percentile, whereas only 3 had NBL below the fifth percentile, and 3 had FNF thickness above the 95th percentile. The FNF/NBL ratio is a promising marker for the sonographic screening of trisomy 21 in the low-risk population; however, further prospective studies including larger numbers of fetuses with trisomy 21 are warranted to determine the clinical value of this marker. As the NBL is dependent on the ethnicity of the population screened, determination of normative data for NBL and the FNF/NBL ratio in different ethnic populations is also recommended before including this method in the routine screening for aneuploidy.

  3. Longwave Stability of Two Liquid Layers Coating Both Sides of a Thick Wall in the Absence of Gravity

    NASA Astrophysics Data System (ADS)

    Dávalos-Orozco, L. A.

    2018-05-01

    A system of two coupled nonlinear equations was calculated to describe the thermocapillary evolution of the free surface deformations of two liquid layers coating both sides of a wall of finite thickness and thermal conductivity in the absence of gravity. The equations were obtained under the small wavenumber approximation. A temperature gradient appears perpendicular to the liquid-wall-liquid system due to the temperature difference between the atmospheres outside the free surfaces of both fluid layers. The linear growth rate of the system was investigated with respect to a variety of parameters. Under some conditions, two stationary modes and one oscillatory mode between them were found. The second stationary mode was concluded to be always stable. It was also found that under different conditions only stationary convection is possible. These results depended on the relative thickness of the two fluid films. It is of interest to know if the coupled free surface perturbations presented a nonlinear sinuous or varicose mode. Thus, a two-dimensional numerical analysis was performed to find out which conditions lead to the sinuous or to the varicose mode of instability.

  4. High-Reynolds-Number Test of a 5-Percent-Thick Low-Aspect-Ratio Semispan Wing in the Langley 0.3-Meter Transonic Cryogenic Tunnel: Wing Pressure Distributions

    NASA Technical Reports Server (NTRS)

    Chu, Julio; Lawing, Pierce L.

    1990-01-01

    A high Reynolds number test of a 5 percent thick low aspect ratio semispan wing was conducted in the adaptive wall test section of the Langley 0.3 m Transonic Cryogenic Tunnel. The model tested had a planform and a NACA 64A-105 airfoil section that is similar to that of the pressure instrumented canard on the X-29 experimental aircraft. Chordwise pressure data for Mach numbers of 0.3, 0.7, and 0.9 were measured for an angle-of-attack range of -4 to 15 deg. The associated Reynolds numbers, based on the geometric mean chord, encompass most of the flight regime of the canard. This test was a free transition investigation. A summary of the wing pressures are presented without analysis as well as adapted test section top and bottom wall pressure signatures. However, the presented graphical data indicate Reynolds number dependent complex leading edge separation phenomena. This data set supplements the existing high Reynolds number database and are useful for computational codes comparison.

  5. Study of the near field wake of trips generating an artificially thick turbulent boundary layers

    NASA Astrophysics Data System (ADS)

    Rodriguez Lopez, Eduardo; Bruce, Paul J. K.; Buxton, Oliver R. H.

    2015-11-01

    The properties of an artificially thick turbulent boundary layer are influenced by its formation mechanism. Previous work has shown that wake or wall-driven mechanisms dominate boundary layer development depending on the trips' aspect ratio. The current study characterizes these two formation mechanisms through the use of high-speed PIV in the near wake of obstacles arrays on a flat plate in a wind tunnel. The time resolved velocity field is studied using Optimal Mode Decomposition (OMD) generating a low order model which captures the representative motions. Results corroborate the original hypothesis and show that these mechanisms are divided in two families: (i) High aspect ratio trips (cylinders) generate vortices with a wall-normal axis which do not transfer information between the wall and the wake of the obstacle. In this case, the boundary layer growth is wall-driven entraining the low-momentum highly turbulent flow above it. (ii) Low aspect ratio trips generate spanwise vorticity increasing the influence of the obstacle's wake in the wall region (wake-driven mechanism). A high level of correlation with the velocity fluctuations at the wall is maintained in case (ii) for the whole wake while in case (i) the correlation vanishes for heights smaller than half obstacle.

  6. Use of computed tomography to identify atrial fibrillation associated differences in left atrial wall thickness and density.

    PubMed

    Dewland, Thomas A; Wintermark, Max; Vaysman, Anna; Smith, Lisa M; Tong, Elizabeth; Vittinghoff, Eric; Marcus, Gregory M

    2013-01-01

    Left atrial (LA) tissue characteristics may play an important role in atrial fibrillation (AF) induction and perpetuation. Although frequently used in clinical practice, computed tomography (CT) has not been employed to describe differences in LA wall properties between AF patients and controls. We sought to noninvasively characterize AF-associated differences in LA tissue using CT. CT images of the LA were obtained in 98 consecutive patients undergoing AF ablation and in 89 controls. A custom software algorithm was used to measure wall thickness and density in four prespecified regions of the LA. On average, LA walls were thinner (-15.5%, 95% confidence interval [CI] -23.2 to -7.8%, P < 0.001) and demonstrated significantly lower density (-19.7 Hounsfield Units [HU], 95% CI -27.0 to -12.5 HU, P < 0.001) in AF patients compared to controls. In linear mixed models adjusting for demographics, clinical variables, and other CT measurements, the average LA, interatrial septum, LA appendage, and anterior walls remained significantly thinner in AF patients. After adjusting for the same potential confounders, history of AF was associated with reduced density in the LA anterior wall and increased density below the right inferior pulmonary vein and in the LA appendage. Application of an automated measurement algorithm to CT imaging of the atrium identified significant thinning of the LA wall and regional alterations in tissue density in patients with a history of AF. These findings suggest differences in LA tissue composition can be noninvasively identified and quantified using CT. ©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.

  7. Hypertensive heart disease versus hypertrophic cardiomyopathy: multi-parametric cardiovascular magnetic resonance discriminators when end-diastolic wall thickness ≥ 15 mm.

    PubMed

    Rodrigues, Jonathan C L; Rohan, Stephen; Ghosh Dastidar, Amardeep; Harries, Iwan; Lawton, Christopher B; Ratcliffe, Laura E; Burchell, Amy E; Hart, Emma C; Hamilton, Mark C K; Paton, Julian F R; Nightingale, Angus K; Manghat, Nathan E

    2017-03-01

    European guidelines state left ventricular (LV) end-diastolic wall thickness (EDWT) ≥15mm suggests hypertrophic cardiomyopathy (HCM), but distinguishing from hypertensive heart disease (HHD) is challenging. We identify cardiovascular magnetic resonance (CMR) predictors of HHD over HCM when EDWT ≥15mm. 2481 consecutive clinical CMRs between 2014 and 2015 were reviewed. 464 segments from 29 HCM subjects with EDWT ≥15mm but without other cardiac abnormality, hypertension or renal impairment were analyzed. 432 segments from 27 HHD subjects with EDWT ≥15mm but without concomitant cardiac pathology were analyzed. Magnitude and location of maximal EDWT, presence of late gadolinium enhancement (LGE), LV asymmetry (>1.5-fold opposing segment) and systolic anterior motion of the mitral valve (SAM) were measured. Multivariate logistic regression was performed. Significance was defined as p<0.05. HHD and HCM cohorts were age-/gender-matched. HHD had significantly increased indexed LV mass (110±27g/m 2 vs. 91±31g/m 2 , p=0.016) but no difference in site or magnitude of maximal EDWT. Mid-wall LGE was significantly more prevalent in HCM. Elevated indexed LVM, mid-wall LGE and absence of SAM were significant multivariate predictors of HHD, but LV asymmetry was not. Increased indexed LV mass, absence of mid-wall LGE and absence of SAM are better CMR discriminators of HHD from HCM than EDWT ≥15mm. • Hypertrophic cardiomyopathy (HCM) is often diagnosed with end-diastolic wall thickness ≥15mm. • Hypertensive heart disease (HHD) can be difficult to distinguish from HCM. • Retrospective case-control study showed that location and magnitude of EDWT are poor discriminators. • Increased left ventricular mass and midwall fibrosis are independent predictors of HHD. • Cardiovascular magnetic resonance parameters facilitate a better discrimination between HHD and HCM.

  8. Effects of increased left ventricular wall thickness on the myocardium in severe aortic stenosis with normal left ventricular ejection fraction: Two- and three-dimensional multilayer speckle tracking echocardiography.

    PubMed

    Cho, Eun Jeong; Park, Sung-Ji; Kim, Eun Kyoung; Lee, Ga Yeon; Chang, Sung-A; Choi, Jin-Oh; Lee, Sang-Chol; Park, Seung Woo

    2017-04-01

    The aim of this study was to determine the capability of real time three-dimensional echocardiography (RT3DE) and two-dimensional (2D) multilayer speckle tracking echocardiography (MSTE) for evaluation of early myocardial dysfunction triggered by increased left ventricular (LV) wall thickness in severe aortic stenosis (AS) with normal LV ejection fraction (EF≥55%). Conventional, RT3D STE and 2D MSTE were performed in 45 patients (mean 68.9±9.0 years) with severe AS (aortic valve area <1 cm 2 , aortic velocity Vmax >4 m/s or mean PG >40 mm Hg) and normal left ventricular ejection fraction (LVEF) without overt coronary artery disease and in 18 age-, sex-matched healthy controls. Global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS), and global radial strain (GRS) were calculated using RT3DE and MSTE. The severe AS group had lower 3D GLS, GRS, GAS and 2D epicardium, and mid-wall and endocardium GLS compared to healthy controls. In MSTE analysis, 2D LS and CS values decreased from the endocardial layer toward the epicardial layer. Severe AS patients with increased LV wall thickness had lower 3D GLS and 2D epicardium, and mid-wall and endocardium GLS compared with severe AS patients without LV wall thickening. GLS on RT3D STE was correlated with GLS on 2D MSTE, left ventricular mass index, LVEF, left atrial volume index, and lnNT-proBNP. RT3DE and 2D MSTE can be used to identify subtle contractile dysfunction triggered by increased LV wall thickness in severe AS with normal LVEF. Therefore, RT3D STE and 2D MSTE may provide additional information that can facilitate decision-making regarding severe AS patients with increased LV wall thickness and normal LV function. © 2017, Wiley Periodicals, Inc.

  9. A prospective clinical study evaluating the development of bowel wall edema during laparoscopic and open visceral surgery.

    PubMed

    Marjanovic, Goran; Kuvendziska, Jasmina; Holzner, Philipp Anton; Glatz, Torben; Sick, Olivia; Seifert, Gabriel; Kulemann, Birte; Küsters, Simon; Fink, Jodok; Timme, Sylvia; Hopt, Ulrich Theodor; Wellner, Ulrich; Keck, Tobias; Karcz, Wojciech Konrad

    2014-12-01

    To examine bowel wall edema development in laparoscopic and open major visceral surgery. In a prospective study, 47 consecutively operated patients with gastric and pancreatic resections were included. Twenty-seven patients were operated in a conventional open procedure (open group) and 20 in a laparoscopic fashion (lap group). In all procedures, a small jejunal segment was resected during standard preparation, of which we measured the dry-wet ratio. Furthermore, HE staining was performed for measuring of bowel wall thickness and edema assessment. Mean value (±std) of dry-wet ratio was significantly lower in the open than in the lap group (0.169 ± 0.017 versus 0.179 ± 0.015; p = 0.03) with the same amount of fluid administration in both groups and a longer infusion interval during laparoscopic surgery. Subgroup analyses (only pancreatic resections) still showed similar results. Histologic examination depicted a significantly larger bowel wall thickness in the open group. Laparoscopic surgery does not seem to lead to the bowel wall edema observed to occur in open surgery regardless of the degree of intravenous fluid administration, thus supporting its use even in major visceral surgery.

  10. A temperature correlation for the radiation resistance of a thick-walled circular duct exhausting a hot gas

    NASA Technical Reports Server (NTRS)

    Mahan, J. R.; Cline, J. G.; Jones, J. D.

    1984-01-01

    It is often useful to know the radiation impedance of an unflanged but thick-walled circular duct exhausting a hot gas into relatively cold surroundings. The reactive component is shown to be insensitive to temperature, but the resistive component is shown to be temperature dependent. A temperature correlation is developed permitting prediction of the radiation resistance from a knowledge of the temperature difference between the ambient air and the gas flowing from the duct, and a physical basis for this correlation is presented.

  11. Associations of anger, anxiety, and depressive symptoms with carotid arterial wall thickness: the multi-ethnic study of atherosclerosis.

    PubMed

    Ohira, Tetsuya; Diez Roux, Ana V; Polak, Joseph F; Homma, Shunichi; Iso, Hiroyasu; Wasserman, Bruce A

    2012-06-01

    Carotid arterial wall thickness, measured as intima-media thickness (IMT), is an early subclinical indicator of cardiovascular disease. Few studies have investigated the association of psychological factors with IMT across multiple ethnic groups and by sex. We included 6561 men and women (2541 whites, 1790 African Americans, 1436 Hispanics, and 794 Chinese) aged 45 to 84 years who took part in the first examination of the Multi-Ethnic Study of Atherosclerosis. Associations of trait anger, trait anxiety, and depressive symptoms with mean values of common carotid artery (CCA) and internal carotid artery (ICA) IMTs were investigated using multivariable regression and logistic models. In age-, sex-, and race/ethnicity-adjusted analyses, the trait anger score was positively associated with CCA and ICA IMTs (mean differences per 1-standard deviation increment of trait anger score were 0.014 [95% confidence interval {CI} = 0.003-0.025, p = .01] and 0.054 [95% CI = 0.017-0.090, p = .004] for CCA and ICA IMTs, respectively). Anger was also associated with the presence of carotid plaque (age-, sex-, and race/ethnicity-adjusted odds ratio per 1-standard deviation increase in trait anger = 1.27 [95% CI = 1.06-1.52]). The associations of the anger score with thicker IMT were attenuated after adjustment for covariates but remained statistically significant. Associations were stronger in men than in women and in whites than in other race/ethnic groups, but heterogeneity was only marginally statistically significant by race/ethnicity. There was no association of depressive symptoms or trait anxiety with IMT. Only one of the three measures examined was associated with IMT, and the patterns seemed to be heterogeneous across race/ethnic groups.

  12. Monte Carlo simulation studies for the determination of microcalcification thickness and glandular ratio through dual-energy mammography

    NASA Astrophysics Data System (ADS)

    Del Lama, L. S.; Godeli, J.; Poletti, M. E.

    2017-08-01

    The majority of breast carcinomas can be associated to the presence of calcifications before the development of a mass. However, the overlapping tissues can obscure the visualization of microcalcification clusters due to the reduced contrast-noise ratio (CNR). In order to overcome this complication, one potential solution is the use of the dual-energy (DE) technique, in which two different images are acquired at low (LE) and high (HE) energies or kVp to highlight specific lesions or cancel out tissue background. In this work, the DE features were computationally studied considering simulated acquisitions from a modified PENELOPE Monte Carlo code. The employed irradiation geometry considered typical distances used in digital mammography, a CsI detection system and an updated breast model composed of skin, microcalcifications and glandular and adipose tissues. The breast thickness ranged from 2 to 6 cm with glandularities of 25%, 50% and 75%, where microcalcifications with dimensions from 100 up to 600 μm were positioned. In general, results pointed an efficiency index better than 87% for the microcalcification thicknesses and better than 95% for the glandular ratio. The simulations evaluated in this work can be used to optimize the elements from the DE imaging chain, in order to become a complementary tool for the conventional single-exposure images, especially for the visualization and estimation of calcification thicknesses and glandular ratios.

  13. Is it better to include necrosis in apparent diffusion coefficient (ADC) measurements? The necrosis/wall ADC ratio to differentiate malignant and benign necrotic lung lesions: Preliminary results.

    PubMed

    Karaman, Adem; Durur-Subasi, Irmak; Alper, Fatih; Durur-Karakaya, Afak; Subasi, Mahmut; Akgun, Metin

    2017-10-01

    To determine whether the use of necrosis/wall apparent diffusion coefficient (ADC) ratios in the differentiation of necrotic lung lesions is more reliable than measuring the wall alone. In this retrospective study, a total of 76 patients (54 males and 22 females, 71% vs. 29%, with a mean age of 53 ± 18 years, range, 18-84) were enrolled, 33 of whom had lung carcinoma and 43 had a benign necrotic lung lesion. A 3T scanner was used. The calculation of the necrosis/wall ADC ratio was based on ADC values measured from necrosis and the wall of the lesions by diffusion-weighted imaging (DWI). Statistical analyses were performed with the independent samples t-test and receiver operating characteristic analysis. Intraobserver and interobserver reliability were calculated for ADC values of wall and necrosis. The mean necrosis/wall ADC ratio was 1.67 ± 0.23 for malignant lesions and 0.75 ± 0.19 for benign lung lesions (P < 0.001). To estimate malignancy the area under the curve (AUC) values for necrosis ADC, wall ADC, and the necrosis/wall ADC ratio were 0.720, 0.073, and 0.997, respectively. A wall/necrosis ADC ratio cutoff value of 1.12 demonstrated a 100% sensitivity and 98% specificity in the estimation of malignancy. Positive predictive value was 100%, and negative predictive value 98% and diagnostic accuracy 99%. There was a good intraobserver and interobserver reliability for wall and necrosis. The necrosis/wall ADC ratio appears to be a reliable and promising tool for discriminating lung carcinoma from benign necrotic lung lesions than measuring the wall alone. 4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1001-1006. © 2017 International Society for Magnetic Resonance in Medicine.

  14. Optimization of wall thickness and lay-up for the shell-like composite structure loaded by non-uniform pressure field

    NASA Astrophysics Data System (ADS)

    Shevtsov, S.; Zhilyaev, I.; Oganesyan, P.; Axenov, V.

    2017-01-01

    The glass/carbon fiber composites are widely used in the design of various aircraft and rotorcraft components such as fairings and cowlings, which have predominantly a shell-like geometry and are made of quasi-isotropic laminates. The main requirements to such the composite parts are the specified mechanical stiffness to withstand the non-uniform air pressure at the different flight conditions and reduce a level of noise caused by the airflow-induced vibrations at the constrained weight of the part. The main objective of present study is the optimization of wall thickness and lay-up of composite shell-like cowling. The present approach assumes conversion of the CAD model of the cowling surface to finite element (FE) representation, then its wind tunnel testing simulation at the different orientation of airflow to find the most stressed mode of flight. Numerical solutions of the Reynolds averaged Navier-Stokes (RANS) equations supplemented by k-w turbulence model provide the spatial distributions of air pressure applied to the shell surface. At the formulation of optimization problem the global strain energy calculated within the optimized shell was assumed as the objective. A wall thickness of the shell had to change over its surface to minimize the objective at the constrained weight. We used a parameterization of the problem that assumes an initiation of auxiliary sphere with varied radius and coordinates of the center, which were the design variables. Curve that formed by the intersection of the shell with sphere defined boundary of area, which should be reinforced by local thickening the shell wall. To eliminate a local stress concentration this increment was defined as the smooth function defined on the shell surface. As a result of structural optimization we obtained the thickness of shell's wall distribution, which then was used to design the draping and lay-up of composite prepreg layers. The global strain energy in the optimized cowling was reduced in2

  15. High vancomycin MICs within the susceptible range in Staphylococcus aureus bacteraemia isolates are associated with increased cell wall thickness and reduced intracellular killing by human phagocytes.

    PubMed

    Falcón, Rocío; Martínez, Alba; Albert, Eliseo; Madrid, Silvia; Oltra, Rosa; Giménez, Estela; Soriano, Mario; Vinuesa, Víctor; Gozalbo, Daniel; Gil, María Luisa; Navarro, David

    2016-05-01

    Vancomycin minimum inhibitory concentrations (MICs) at the upper end of the susceptible range for Staphylococcus aureus have been associated with poor clinical outcomes of bloodstream infections. We tested the hypothesis that high vancomycin MICs in S. aureus bacteraemia isolates are associated with increased cell wall thickness and suboptimal bacterial internalisation or lysis by human phagocytes. In total, 95 isolates were evaluated. Original vancomycin MICs were determined by Etest. The susceptibility of S. aureus isolates to killing by phagocytes was assessed in a human whole blood assay. Internalisation of bacterial cells by phagocytes was investigated by flow cytometry. Cell wall thickness was evaluated by transmission electron microscopy. Genotypic analysis of S. aureus isolates was performed using a DNA microarray system. Vancomycin MICs were significantly higher (P=0.006) in isolates that were killed suboptimally (killing index <60%) compared with those killed efficiently (killing index >70%) and tended to correlate inversely (P=0.08) with the killing indices. Isolates in both killing groups were internalised by human neutrophils and monocytes with comparable efficiency. The cell wall was significantly thicker (P=0.03) in isolates in the low killing group. No genotypic differences were found between the isolates in both killing groups. In summary, high vancomycin MICs in S. aureus bacteraemia isolates were associated with increased cell wall thickness and reduced intracellular killing by phagocytes. Copyright © 2016 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  16. Effect of wall to total temperature ratio variation on heat transfer to the leeside of a space shuttle configuration at M equals 10.3

    NASA Technical Reports Server (NTRS)

    Dunavant, J. C.

    1974-01-01

    An experimental study has been conducted of the influence of wall to total temperature ratio on the heat transfer to the leeside of a 040A space shuttle configuration. The heat transfer tests were made at a Mach number of 10 and a Reynolds number of one million per foot for angles of attack from 0 deg to 30 deg. Range of wall to total temperature ratio was from 0.16 to 0.43. Where the heat transfer was relatively high and the laminar boundary layer attached, the local heat transfer decreased by about 20 percent as the wall to total temperature ratio was increased from the minimum to the maximum test value. On regions of separated flow and vortex reattachment, very low heating rates were measured at some conditions and indicate significant changes are occurring in the leeside flow field. No single trend of heat transfer variation with wall to total temperature ratio could be observed.

  17. Mechanical Properties of Additively Manufactured Thick Honeycombs.

    PubMed

    Hedayati, Reza; Sadighi, Mojtaba; Mohammadi Aghdam, Mohammad; Zadpoor, Amir Abbas

    2016-07-23

    Honeycombs resemble the structure of a number of natural and biological materials such as cancellous bone, wood, and cork. Thick honeycomb could be also used for energy absorption applications. Moreover, studying the mechanical behavior of honeycombs under in-plane loading could help understanding the mechanical behavior of more complex 3D tessellated structures such as porous biomaterials. In this paper, we study the mechanical behavior of thick honeycombs made using additive manufacturing techniques that allow for fabrication of honeycombs with arbitrary and precisely controlled thickness. Thick honeycombs with different wall thicknesses were produced from polylactic acid (PLA) using fused deposition modelling, i.e., an additive manufacturing technique. The samples were mechanically tested in-plane under compression to determine their mechanical properties. We also obtained exact analytical solutions for the stiffness matrix of thick hexagonal honeycombs using both Euler-Bernoulli and Timoshenko beam theories. The stiffness matrix was then used to derive analytical relationships that describe the elastic modulus, yield stress, and Poisson's ratio of thick honeycombs. Finite element models were also built for computational analysis of the mechanical behavior of thick honeycombs under compression. The mechanical properties obtained using our analytical relationships were compared with experimental observations and computational results as well as with analytical solutions available in the literature. It was found that the analytical solutions presented here are in good agreement with experimental and computational results even for very thick honeycombs, whereas the analytical solutions available in the literature show a large deviation from experimental observation, computational results, and our analytical solutions.

  18. Mechanical Properties of Additively Manufactured Thick Honeycombs

    PubMed Central

    Hedayati, Reza; Sadighi, Mojtaba; Mohammadi Aghdam, Mohammad; Zadpoor, Amir Abbas

    2016-01-01

    Honeycombs resemble the structure of a number of natural and biological materials such as cancellous bone, wood, and cork. Thick honeycomb could be also used for energy absorption applications. Moreover, studying the mechanical behavior of honeycombs under in-plane loading could help understanding the mechanical behavior of more complex 3D tessellated structures such as porous biomaterials. In this paper, we study the mechanical behavior of thick honeycombs made using additive manufacturing techniques that allow for fabrication of honeycombs with arbitrary and precisely controlled thickness. Thick honeycombs with different wall thicknesses were produced from polylactic acid (PLA) using fused deposition modelling, i.e., an additive manufacturing technique. The samples were mechanically tested in-plane under compression to determine their mechanical properties. We also obtained exact analytical solutions for the stiffness matrix of thick hexagonal honeycombs using both Euler-Bernoulli and Timoshenko beam theories. The stiffness matrix was then used to derive analytical relationships that describe the elastic modulus, yield stress, and Poisson’s ratio of thick honeycombs. Finite element models were also built for computational analysis of the mechanical behavior of thick honeycombs under compression. The mechanical properties obtained using our analytical relationships were compared with experimental observations and computational results as well as with analytical solutions available in the literature. It was found that the analytical solutions presented here are in good agreement with experimental and computational results even for very thick honeycombs, whereas the analytical solutions available in the literature show a large deviation from experimental observation, computational results, and our analytical solutions. PMID:28773735

  19. Optimization of an asymmetric thin-walled tube in rotary draw bending process

    NASA Astrophysics Data System (ADS)

    Xue, Xin; Liao, Juan; Vincze, Gabriela; Gracio, Jose J.

    2013-12-01

    The rotary draw bending is one of the advanced thin-walled tube forming processes with high efficiency, low consumption and good flexibility in several industries such as automotive, aerospace and shipping. However it may cause undesirable deformations such as over-thinning and ovalization, which bring the weakening of the strength and difficulties in the assembly process respectively. Accurate modeling and effective optimization design to eliminate or reduce undesirable deformations in tube bending process have been a challenging topic. In this paper, in order to study the deformation behaviors of an asymmetric thin-walled tube in rotary draw bending process, a 3D elastic-plastic finite element model has been built under the ABAQUS environment, and the reliability of the model is validated by comparison with experiment. Then, the deformation mechanism of thin-walled tube in bending process was briefly analysis and the effects of wall thickness ratio, section height width ratio and mandrel extension on wall thinning and ovalization in bending process were investigated by using Response Surface Methodology. Finally, multi-objective optimization method was used to obtain an optimum solution of design variables based on simulation results.

  20. 49 CFR 179.400-8 - Thickness of plates.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Specification for Cryogenic Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400... welded joints, except that for seamless heads, E = 1.0. (b) The minimum wall thickness, after forming, of..., except that for seamless heads, E=1.0. (c) The minimum wall thickness, after forming, of a flanged and...

  1. Thickness ratio effects on quasistatic actuation and sensing behavior of laminate magnetoelectric cantilevers

    NASA Astrophysics Data System (ADS)

    Wang, Yezuo; Atulasimha, Jayasimha; Clarke, Joshua; Sundaresan, Vishnu B.

    2010-04-01

    In this work, the magnetoelectric cantilever composed of a layer of Galfenol and a layer of PZT-5H is studied for novel applications such as surgical ablation tools and cutting tools for machining applications. For developing a suitable model for the magnetoelectric cantilever, an energy based approach for the non-linear constitutive behavior of the magnetostrictive material and linear piezoelectric constitutive equations will be coupled with Euler Bernoulli model for composite beams. The cantilever is held in a uniform magnetic field and the magnetic field is measured by a Gaussmeter. The tip-deflection of the cantilever is detected by a laser triangulation sensor. The piezoelectric response can be studied with low noise preamplifier. Four PZT-5H layers with different thickness are separately bonded on the top of the same Galfenol layer and characterized to study the thickness ratio effects on the quasistatic actuation and sensing behavior of the composite cantilever.

  2. Corrections to the thin wall approximation in general relativity

    NASA Technical Reports Server (NTRS)

    Garfinkle, David; Gregory, Ruth

    1989-01-01

    The question is considered whether the thin wall formalism of Israel applies to the gravitating domain walls of a lambda phi(exp 4) theory. The coupled Einstein-scalar equations that describe the thick gravitating wall are expanded in powers of the thickness of the wall. The solutions of the zeroth order equations reproduce the results of the usual Israel thin wall approximation for domain walls. The solutions of the first order equations provide corrections to the expressions for the stress-energy of the wall and to the Israel thin wall equations. The modified thin wall equations are then used to treat the motion of spherical and planar domain walls.

  3. Study on thickness distribution of thermoformed medical PVC blister

    NASA Astrophysics Data System (ADS)

    Li, Yiping

    2017-08-01

    Vacuum forming has many advantages over other plastic forming processes due to its cost effectiveness, time efficiency, higher product precision, and more design flexibility. Nevertheless, when pressures greater than the atmospheric value are required to force the thermo-plastic into more intimate contact with the mold surface, pressure forming is a better choice. This paper studies the process of air-pressure thermoforming of plastic sheet, and focuses on medical blister PVC products. ANSYS POLYFLOW tool is used to simulate the process and analyze the wall thickness distribution of the blister. The influence of mold parameters on the wall thickness distribution of thermoformed part is thus obtained through simulation. Increasing radius between mold and side wall at the bottom of blister and draft prove to improve the wall thickness distribution.

  4. Prenasal thickness to nasal bone length ratio: effectiveness as a second or third trimester marker for Down syndrome.

    PubMed

    Tournemire, A; Groussolles, M; Ehlinger, V; Lusque, A; Morin, M; Benevent, J B; Arnaud, C; Vayssière, C

    2015-08-01

    To assess the value of the prenasal thickness to nasal bone length ratio (PT/NBL) for detecting trisomy 21 (T21) after the first trimester. Two examiners blinded to fetal T21 status retrospectively measured prenasal thickness (PT) and nasal bone length (NBL) of T21 and control fetuses at 15-36 weeks' gestational age on two-dimensional images from all T21-screening ultrasounds from November 2010 to April 2013. ROC curve analysis and its diagnostic values determined the best cut-off value for the ratio. Interobserver reproducibility was assessed. Good quality ultrasound profile images were available for 26 fetuses with T21 compared to 91 normal fetuses. The median PT/NBL ratio was 1.28 for T21 and 0.73 for control fetuses (p<0.0001). The PT/NBL ratio performed significantly better (AUC 0.99; 95%CI 0.97-1) than either PT (0.82; 0.73-0.91) or NBL (0.91; 0.85-0.98). The optimal PT/NBL ratio cut-off was 0.98, with a sensitivity of 88.5% [76.2-100%] and a specificity of 100%. Interobserver variability was low. The PT/NBL ratio is a strong marker for detecting T21 in the second and third trimesters, significantly more effective than either indicator alone. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  5. Mechanical properties investigation on single-wall ZrO2 nanotubes: A finite element method with equivalent Poisson's ratio for chemical bonds

    NASA Astrophysics Data System (ADS)

    Yang, Xiao; Li, Huijian; Hu, Minzheng; Liu, Zeliang; Wärnå, John; Cao, Yuying; Ahuja, Rajeev; Luo, Wei

    2018-04-01

    A method to obtain the equivalent Poisson's ratio in chemical bonds as classical beams with finite element method was proposed from experimental data. The UFF (Universal Force Field) method was employed to calculate the elastic force constants of Zrsbnd O bonds. By applying the equivalent Poisson's ratio, the mechanical properties of single-wall ZrNTs (ZrO2 nanotubes) were investigated by finite element analysis. The nanotubes' Young's modulus (Y), Poisson's ratio (ν) of ZrNTs as function of diameters, length and chirality have been discussed, respectively. We found that the Young's modulus of single-wall ZrNTs is calculated to be between 350 and 420 GPa.

  6. Margin to tumor thickness ratio - A predictor of local recurrence and survival in oral squamous cell carcinoma.

    PubMed

    Heiduschka, Gregor; Virk, Sohaib A; Palme, Carsten E; Ch'ng, Sydney; Elliot, Michael; Gupta, Ruta; Clark, Jonathan

    2016-04-01

    To assess whether small oral squamous cell carcinomas (OSCC) require the same margin clearance as large tumors. We evaluated the association between the ratio of the closest margin to tumor size (MSR) and tumor thickness (MTR) with local control and survival. The clinicopathologic and follow up data were obtained for 501 OSCC patients who had surgical resection with curative intent at our institution. MTR and MSR were computed and their associations with local control and survival were assessed using multivariable Cox-regression model. Survival curves were generated using the Kaplan-Meier method. MTR was a better predictor of disease control than MSR. MTR was a predictor of local failure (p=0.033) and disease specific death (p=0.038) after adjusting for perineural invasion, lymphovascular involvement, nodal status, and radiotherapy. A threshold MTR value of 0.3 was identified, above which the risk of local recurrence was low. The ratio of margin to tumor thickness was an independent predictor for local recurrence and disease specific death in this cohort. A MTR>0.3 can serve as a useful tool for adjuvant therapy planning as it combines tumor thickness and margin clearance, two well established prognostic factors. The minimum safe margin can be calculated by multiplying the tumor thickness by 0.3. Further prospective studies in other institutions are warranted to confirm the prognostic utility of MTR and assess the generalizability of our threshold values. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Accuracy Evaluation in the Measurement of a Small Change in the Thickness of Arterial Walls and the Measurement of Elasticity of the Human Carotid Artery

    NASA Astrophysics Data System (ADS)

    Hasegawa, Hideyuki; Kanai, Hiroshi; Hoshimiya, Nozomu; Chubachi, Noriyoshi; Koiwa, Yoshiro

    1998-05-01

    For the diagnosis of the early stages of atherosclerosis, it isimportant to evaluate the local acoustic characteristics of thearterial wall. For this purpose, it is necessary to increase thespatial resolution in the axial direction to several millimeters,which corresponds to the size of the macular lesion on the surface ofthe wall. We have proposed a method for measuring small velocitysignals on the intima and adventitia of the arterial wall from theskin surface using pulsive ultrasonic waves. The small change inthickness of the arterial wall is obtained by integrating thedifference between the two velocity signals on the intima andadventitia. The elastic property of the arterial wall is noninvasivelyevaluated from the change in thickness and the arterial innerpressure. In this paper, we evaluate the accuracy of the proposedmethod for measuring the small displacement. Moreover, we applied thismethod to evaluate the elastic property of the arterial wall of 50patients and 8 healthy subjects.

  8. Measurements in the near-wall region of a relaxing three-dimensional low speed turbulent air boundary layer

    NASA Technical Reports Server (NTRS)

    Hebbar, K. S.; Melnik, W. L.

    1976-01-01

    An experimental investigation was conducted at selected locations of the near-wall region of a three dimensional turbulent air boundary layer relaxing in a nominally zero external pressure gradient behind a transverse hump (in the form of a 30 deg swept, 5-foot chord wing-type model) faired into the side wall of a low speed wind tunnel. Wall shear stresses measured with a flush-mounted hot-film gage and a sublayer fence were in very good agreement with experimental data obtained with two Preston probes. With the upstream unit Reynolds number held constant at 325,000/ft. approximately one-fourth of the boundary layer thickness adjacent to the wall was surveyed with a single rotated hot-wire probe mounted on a specially designed minimum interference traverse mechanism. The boundary layer (approximately 3.5 in thick near the first survey station where the length Reynolds number was 5.5 million) had a maximum crossflow velocity ratio of 0.145 and a maximum crossflow angle of 21.875 deg close to the wall.

  9. Ellipsometric measurement of liquid film thickness

    NASA Technical Reports Server (NTRS)

    Chang, Ki Joon; Frazier, D. O.

    1989-01-01

    The immediate objective of this research is to measure liquid film thickness from the two equilibrium phases of a monotectic system in order to estimate the film pressure of each phase. Thus liquid film thicknesses on the inside walls of the prism cell above the liquid level have been measured elliposmetrically for the monotectic system of succinonitrile and water. The thickness varies with temperature and composition of each plane. The preliminary results from both layers at 60 deg angle of incidence show nearly uniform thickness from about 21 to 23 C. The thickness increases with temperature but near 30 C the film appears foggy and scatters the laser beam. As the temperature of the cell is raised beyond room temperature it becomes increasingly difficult to equalize the temperature inside and outside the cell. The fogging may also be an indication that solution, not pure water, is adsorbed onto the substrate. Nevertheless, preliminary results suggest that ellipsometric measurement is feasible and necessary to measure more accurately and rapidly the film thickness and to improve thermal control of the prism walls.

  10. Fabrication of a high aspect ratio thick silicon wafer mold and electroplating using flipchip bonding for MEMS applications

    NASA Astrophysics Data System (ADS)

    Kim, Bong-Hwan; Kim, Jong-Bok

    2009-06-01

    We have developed a microfabrication process for high aspect ratio thick silicon wafer molds and electroplating using flipchip bonding with THB 151N negative photoresist (JSR micro). This fabrication technique includes large area and high thickness silicon wafer mold electroplating. The process consists of silicon deep reactive ion etching (RIE) of the silicon wafer mold, photoresist bonding between the silicon mold and the substrate, nickel electroplating and a silicon removal process. High thickness silicon wafer molds were made by deep RIE and flipchip bonding. In addition, nickel electroplating was developed. Dry film resist (ORDYL MP112, TOK) and thick negative-tone photoresist (THB 151N, JSR micro) were used as bonding materials. In order to measure the bonding strength, the surface energy was calculated using a blade test. The surface energy of the bonding wafers was found to be 0.36-25.49 J m-2 at 60-180 °C for the dry film resist and 0.4-1.9 J m-2 for THB 151N in the same temperature range. Even though ORDYL MP112 has a better value of surface energy than THB 151N, it has a critical disadvantage when it comes to removing residue after electroplating. The proposed process can be applied to high aspect ratio MEMS structures, such as air gap inductors or vertical MEMS probe tips.

  11. Aspect ratio has no effect on genotoxicity of multi-wall carbon nanotubes.

    PubMed

    Kim, Jin Sik; Lee, Kyu; Lee, Young Hee; Cho, Hyun Sun; Kim, Ki Heon; Choi, Kyung Hee; Lee, Sang Hee; Song, Kyung Seuk; Kang, Chang Soo; Yu, Il Je

    2011-07-01

    Carbon nanotubes (CNTs) have specific physico-chemical and electrical properties that are useful for telecommunications, medicine, materials, manufacturing processes and the environmental and energy sectors. Yet, despite their many advantages, it is also important to determine whether CNTs may represent a hazard to the environment and human health. Like asbestos, the aspect ratio (length:diameter) and metal components of CNTs are known to have an effect on the toxicity of carbon nanotubes. Thus, to evaluate the toxic potential of CNTs in relation to their aspect ratio and metal contamination, in vivo and in vitro genotoxicity tests were conducted using high-aspect-ratio (diameter: 10-15 nm, length: ~10 μm) and low-aspect-ratio multi-wall carbon nanotubes (MWCNTs, diameter: 10-15 nm, length: ~150 nm) according to OECD test guidelines 471 (bacterial reverse mutation test), 473 (in vitro chromosome aberration test), and 474 (in vivo micronuclei test) with a good laboratory practice system. To determine the treatment concentration for all the tests, a solubility and dispersive test was performed, and a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) solution found to be more suitable than distilled water. Neither the high- nor the low-aspect-ratio MWCNTs induced any genotoxicity in a bacterial reverse mutation test (~1,000 μg/plate), in vitro chromosome aberration test (without S9: ~6.25 μg/ml, with S9: ~50 μg/ml), or in vivo micronuclei test (~50 mg/kg). However, the high-aspect-ratio MWCNTs were found to be more toxic than the low-aspect-ratio MWCNTs. Thus, while high-aspect-ratio MWCNTs do not induce direct genotoxicity or metabolic activation-mediated genotoxicity, genotoxicity could still be induced indirectly through oxidative stress or inflammation.

  12. Variable impact of CSF flow suppression on quantitative 3.0T intracranial vessel wall measurements.

    PubMed

    Cogswell, Petrice M; Siero, Jeroen C W; Lants, Sarah K; Waddle, Spencer; Davis, L Taylor; Gilbert, Guillaume; Hendrikse, Jeroen; Donahue, Manus J

    2018-03-31

    Flow suppression techniques have been developed for intracranial (IC) vessel wall imaging (VWI) and optimized using simulations; however, simulation results may not translate in vivo. To evaluate experimentally how IC vessel wall and lumen measurements change in identical subjects when evaluated using the most commonly available blood and cerebrospinal fluid (CSF) flow suppression modules and VWI sequences. Prospective. Healthy adults (n = 13; age = 37 ± 15 years) were enrolled. A 3.0T 3D T 1 /proton density (PD)-weighted turbo-spin-echo (TSE) acquisition with post-readout anti-driven equilibrium module, with and without Delay-Alternating-with-Nutation-for-Tailored-Excitation (DANTE) was applied. DANTE flip angle (8-12°) and TSE refocusing angle (sweep = 40-120° or 50-120°) were varied. Basilar artery and internal carotid artery (ICA) wall thicknesses, CSF signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and signal ratio (SR) were assessed. Measurements were made by two readers (radiology resident and board-certified neuroradiologist). A Wilcoxon signed-rank test was applied with corrected two-sided P < 0.05 required for significance (critical P = 0.008, 0.005, and 0.05 for SNR/CNR, SR, and wall thickness, respectively). A TSE pulse sweep = 40-120° and sweep = 50-120° provided similar (P = 0.55) CSF suppression. Addition of the DANTE preparation reduced CSF SNR from 17.4 to 6.7, thereby providing significant (P < 0.008) improvement in CSF suppression. The DANTE preparation also resulted in a significant (P < 0.008) reduction in vessel wall SNR, but variable vessel wall to CSF CNR improvement (P = 0.87). There was a trend for a difference in blood SNR with vs. without DANTE (P = 0.05). The outer vessel wall diameter and wall thickness values were lower (P < 0.05) with (basilar artery 4.45 mm, 0.81 mm, respectively) vs. without (basilar artery 4.88 mm, 0.97 mm, respectively) DANTE 8

  13. Compliance of the abdominal wall during laparoscopic insufflation.

    PubMed

    Becker, Chuck; Plymale, Margaret A; Wennergren, John; Totten, Crystal; Stigall, Kyle; Roth, J Scott

    2017-04-01

    To provide adequate workspace between the viscera and abdominal wall, insufflation with carbon dioxide is a common practice in laparoscopic surgeries. An insufflation pressure of 15 mmHg is considered to be safe in patients, but all insufflation pressures create perioperative and postoperative physiologic effects. As a composition of viscoelastic materials, the abdominal wall should distend in a predictable manner given the pressure of the pneumoperitoneum. The purpose of this study was to elucidate the relationship between degree of abdominal distention and the insufflation pressure, with the goal of determining factors which impact the compliance of the abdominal wall. A prospective, IRB-approved study was conducted to video record the abdomens of patients undergoing insufflation prior to a laparoscopic surgery. Photo samples were taken every 5 s, and the strain of the patient's abdomen in the sagittal plane was determined, as well as the insufflator pressure (stress) at bedside. Patients were insufflated to 15 mmHg. The relationship between the stress and strain was determined in each sample, and compliance of the patient's abdominal wall was calculated. Subcutaneous fat thickness and rectus abdominus muscle thickness were obtained from computed tomography scans. Correlations between abdominal wall compliances and subcutaneous fat and muscle content were determined. Twenty-five patients were evaluated. An increased fat thickness in the abdominal wall had a direct exponential relationship with abdominal wall compliance (R 2  = 0.59, p < 0.05). There was no correlation between muscle and fat thickness. All insufflation pressures create perioperative and postoperative complications. The compliance of patients' abdominal body walls differs, and subcutaneous fat thickness has a direct exponential relationship with abdominal wall compliance. Thus, insufflation pressures can be better tailored per the patient. Future studies are needed to demonstrate the

  14. Time-dependent fracture probability of bilayer, lithium-disilicate-based, glass-ceramic, molar crowns as a function of core/veneer thickness ratio and load orientation.

    PubMed

    Anusavice, Kenneth J; Jadaan, Osama M; Esquivel-Upshaw, Josephine F

    2013-11-01

    Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure. The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading. Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic). Predicted fracture probabilities (Pf) for centrally loaded 1.6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8mm/0.8mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4mm/1.2mm). CARES/Life results support the proposed crown design and load orientation hypotheses. The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. Copyright © 2013 Academy of Dental Materials. All rights reserved.

  15. Time-dependent fracture probability of bilayer, lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation

    PubMed Central

    Anusavice, Kenneth J.; Jadaan, Osama M.; Esquivel–Upshaw, Josephine

    2013-01-01

    Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure. Objective The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6 mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading. Materials and methods Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic). Results Predicted fracture probabilities (Pf) for centrally-loaded 1,6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8 mm/0.8 mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4 mm/1.2 mm). Conclusion CARES/Life results support the proposed crown design and load orientation hypotheses. Significance The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. PMID:24060349

  16. Elastic torsional buckling of thin-walled composite cylinders

    NASA Technical Reports Server (NTRS)

    Marlowe, D. E.; Sushinsky, G. F.; Dexter, H. B.

    1974-01-01

    The elastic torsional buckling strength has been determined experimentally for thin-walled cylinders fabricated with glass/epoxy, boron/epoxy, and graphite/epoxy composite materials and composite-reinforced aluminum and titanium. Cylinders have been tested with several unidirectional-ply orientations and several cross-ply layups. Specimens were designed with diameter-to-thickness ratios of approximately 150 and 300 and in two lengths of 10 in. and 20 in. The results of these tests were compared with the buckling strengths predicted by the torsional buckling analysis of Chao.

  17. Manufacture of high aspect ratio micro-pillar wall shear stress sensor arrays

    NASA Astrophysics Data System (ADS)

    Gnanamanickam, Ebenezer P.; Sullivan, John P.

    2012-12-01

    In the field of experimental fluid mechanics the measurement of unsteady, distributed wall shear stress has proved historically challenging. Recently, sensors based on an array of flexible micro-pillars have shown promise in carrying out such measurements. Similar sensors find use in other applications such as cellular mechanics. This work presents a manufacturing technique that can manufacture micro-pillar arrays of high aspect ratio. An electric discharge machine (EDM) is used to manufacture a micro-drilling tool. This micro-drilling tool is used to form holes in a wax sheet which acts as the mold for the micro-pillar array. Silicone rubber is cast in these molds to yield a micro-pillar array. Using this technique, micro-pillar arrays with a maximum aspect ratio of about 10 have been manufactured. Manufacturing issues encountered, steps to alleviate them and the potential of the process to manufacture similar micro-pillar arrays in a time-efficient manner are also discussed.

  18. Responses of retaining wall and surrounding ground to pre-excavation dewatering in an alternated multi-aquifer-aquitard system

    NASA Astrophysics Data System (ADS)

    Zeng, Chao-Feng; Xue, Xiu-Li; Zheng, Gang; Xue, Teng-Yun; Mei, Guo-Xiong

    2018-04-01

    Pre-excavation dewatering (PED) is an important construction stage in deep excavation. Field measurements show that retaining walls can develop obvious deflections during PED, which has been rarely considered in the past. The characteristics of PED-induced wall deflection, and the relationship of this deflection to surrounding ground deformation are still unclear. In this study, a PED test is simulated by a numerical model. The model is verified by field observations and used to investigate the responses of retaining wall and surrounding ground to PED. Results indicate that the maximum wall defection (δhm) and surface settlement (δvm) can all reach centimeter level under common conditions of PED. The ratio of δvm to δhm varies at the range of 0.45-0.67. Wall and soil deformations will be more obvious if the soils within the dewatering depth (Hd) have better permeability. The relative positions between Hd and strata (i.e., aquifer or aquitard) have great influence on the PED-induced deformations. If an aquifer appears below Hd, further increasing Hd can induce a rapid growth of wall and soil deformations. If thick aquitard appears below Hd, the deformation increments by further increasing Hd are not apparent. However, once Hd exceeds the center of the thick aquitard and reaches a thick confined aquifer, the wall deflections and soil deformation zones behind the wall will enlarge significantly. Meanwhile, a large bending moment in the retaining wall will arise around the bottom of the confined aquifer. The designers should consider this condition and allocate enough steel rebars there, preventing the appearance of wall cracks in the confined aquifer.

  19. Space-Time Correlations and Spectra of Wall Pressure in a Turbulent Boundary Layer

    NASA Technical Reports Server (NTRS)

    Willmarth, W. W.

    1959-01-01

    Measurements of the statistical properties of the fluctuating wall pressure produced by a subsonic turbulent boundary layer are described. The measurements provide additional information about the structure of the turbulent boundary layer; they are applicable to the problems of boundary-layer induced noise inside an airplane fuselage and to the generation of waves-on water. The spectrum of the wall pressure is presented in dimensionless form. The ratio of the root-mean-square wall pressure to the free-stream dynamic pressure is found to be a constant square root of bar P(sup 2)/q(sub infinity) = 0.006 independent of Mach number and Reynolds number. In addition, space- time correlation measurements in the stream direction show that pressure fluctuations whose scale is greater than or equal to 0.3 times the boundary-layer thickness are convected with the convection speed U(sub c) = 0.82U(sub infinity) where U(infinity) is the free-stream velocity and have lost their identity in a distance approximately equal to 10 boundary-layer thicknesses.

  20. Investigation of blown boundary layers with an improved wall jet system

    NASA Technical Reports Server (NTRS)

    Saripalli, K. R.; Simpson, R. L.

    1980-01-01

    Measurements were made in a two dimensional incompressible wall jet submerged under a thick upstream boundary layer with a zero pressure gradient and an adverse pressure gradient. The measurements included mean velocity and Reynolds stresses profiles, skin friction, and turbulence spectra. The measurements were confined to practical ratios (less than 2) of the jet velocity to the free stream velocity. The wall jet used in the experiments had an asymmetric velocity profile with a relatively higher concentration of momentum away from the wall. An asymmetric jet velocity profile has distinct advantages over a uniform jet velocity profile, especially in the control of separation. Predictions were made using Irwin's (1974) method for blown boundary layers. The predictions clearly show the difference in flow development between an asymmetric jet velocity profile and a uniform jet velocity profile.

  1. Statistical comparison of methods for estimating sediment thickness from Horizontal-to-Vertical Spectral Ratio (HVSR) seismic methods: An example from Tylerville, Connecticut, USA

    USGS Publications Warehouse

    Johnson, Carole D.; Lane, John W.

    2016-01-01

    Determining sediment thickness and delineating bedrock topography are important for assessing groundwater availability and characterizing contamination sites. In recent years, the horizontal-to-vertical spectral ratio (HVSR) seismic method has emerged as a non-invasive, cost-effective approach for estimating the thickness of unconsolidated sediments above bedrock. Using a three-component seismometer, this method uses the ratio of the average horizontal- and vertical-component amplitude spectrums to produce a spectral ratio curve with a peak at the fundamental resonance frequency. The HVSR method produces clear and repeatable resonance frequency peaks when there is a sharp contrast (>2:1) in acoustic impedance at the sediment/bedrock boundary. Given the resonant frequency, sediment thickness can be determined either by (1) using an estimate of average local sediment shear-wave velocity or by (2) application of a power-law regression equation developed from resonance frequency observations at sites with a range of known depths to bedrock. Two frequently asked questions about the HVSR method are (1) how accurate are the sediment thickness estimates? and (2) how much do sediment thickness/bedrock depth estimates change when using different published regression equations? This paper compares and contrasts different approaches for generating HVSR depth estimates, through analysis of HVSR data acquired in the vicinity of Tylerville, Connecticut, USA.

  2. Mechanosensation Dynamically Coordinates Polar Growth and Cell Wall Assembly to Promote Cell Survival.

    PubMed

    Davì, Valeria; Tanimoto, Hirokazu; Ershov, Dmitry; Haupt, Armin; De Belly, Henry; Le Borgne, Rémi; Couturier, Etienne; Boudaoud, Arezki; Minc, Nicolas

    2018-04-23

    How growing cells cope with size expansion while ensuring mechanical integrity is not known. In walled cells, such as those of microbes and plants, growth and viability are both supported by a thin and rigid encasing cell wall (CW). We deciphered the dynamic mechanisms controlling wall surface assembly during cell growth, using a sub-resolution microscopy approach to monitor CW thickness in live rod-shaped fission yeast cells. We found that polar cell growth yielded wall thinning and that thickness negatively influenced growth. Thickness at growing tips exhibited a fluctuating behavior with thickening phases followed by thinning phases, indicative of a delayed feedback promoting thickness homeostasis. This feedback was mediated by mechanosensing through the CW integrity pathway, which probes strain in the wall to adjust synthase localization and activity to surface growth. Mutants defective in thickness homeostasis lysed by rupturing the wall, demonstrating its pivotal role for walled cell survival. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Velocity distribution in a turbulent flow near a rough wall

    NASA Astrophysics Data System (ADS)

    Korsun, A. S.; Pisarevsky, M. I.; Fedoseev, V. N.; Kreps, M. V.

    2017-11-01

    Velocity distribution in the zone of developed wall turbulence, regardless of the conditions on the wall, is described by the well-known Prandtl logarithmic profile. In this distribution, the constant, that determines the value of the velocity, is determined by the nature of the interaction of the flow with the wall and depends on the viscosity of the fluid, the dynamic velocity, and the parameters of the wall roughness.In extreme cases depending on the ratio between the thickness of the viscous sublayer and the size of the roughness the constant takes on a value that does not depend on viscosity, or leads to a ratio for a smooth wall.It is essential that this logarithmic profile is the result not only of the Prandtl theory, but can be derived from general considerations of the theory of dimensions, and also follows from the condition of local equilibrium of generation and dissipation of turbulent energy in the wall area. This allows us to consider the profile as a universal law of velocity distribution in the wall area of a turbulent flow.The profile approximation up to the maximum speed line with subsequent integration makes possible to obtain the resistance law for channels of simple shape. For channels of complex shape with rough walls, the universal profile can be used to formulate the boundary condition when applied to the calculation of turbulence models.This paper presents an empirical model for determining the constant of the universal logarithmic profile. The zone of roughness is described by a set of parameters and is considered as a porous structure with variable porosity.

  4. Further studies of turbulence structure resulting from interactions between embedded vortices and wall jets at high blowing ratios

    NASA Astrophysics Data System (ADS)

    Doner, William D.

    1989-12-01

    Interactions of wall jets and vortices embedded in turbulent layers commonly occur near gas turbine blades and endwalls where film cooling is employed. These interactions frequently result in undesirable heat transfer effects at blade and endwall surfaces. In this thesis, a crossed hot-wire probe is used to measure the turbulence structure resulting from this type of interaction. The vortex is generated using a half delta-wing vortex generator mounted 12 deg with respect to a 10 m/s mean velocity flow over a flat plate. A single injection hole, 0.95 cm in diameter, inclined 30 deg to the horizontal, is positioned 59.3 cm downstream of the vortex generator. The vortex generator is positioned so that vortex upwash and downwash could be located over the injection hole. Streamwise development of the turbulent boundary layer was investigated for the following cases: (1) boundary layer with jet only (m = 1.5), and (2) boundary layer with vortex only. Measurement of interaction between the boundary layer, vortex upwash, and the wall jet was made at one station with various blowing ratios. At low blowing ratios (m = 0.5 and 1.5) the vortex dominates the flow. Significant alterations to the turbulent structure are seen in the Reynolds stress components, vorticity distributions and mean velocities. At higher blowing ratios (m = 2.5 and 3.5) the jet dominates the flow, the vortex is blown away from the wall, and its turbulence effects are dispersed over a larger area.

  5. Ballistic Limit Equation for Single Wall Titanium

    NASA Technical Reports Server (NTRS)

    Ratliff, J. M.; Christiansen, Eric L.; Bryant, C.

    2009-01-01

    Hypervelocity impact tests and hydrocode simulations were used to determine the ballistic limit equation (BLE) for perforation of a titanium wall, as a function of wall thickness. Two titanium alloys were considered, and separate BLEs were derived for each. Tested wall thicknesses ranged from 0.5mm to 2.0mm. The single-wall damage equation of Cour-Palais [ref. 1] was used to analyze the Ti wall's shielding effectiveness. It was concluded that the Cour-Palais single-wall equation produced a non-conservative prediction of the ballistic limit for the Ti shield. The inaccurate prediction was not a particularly surprising result; the Cour-Palais single-wall BLE contains shield material properties as parameters, but it was formulated only from tests of different aluminum alloys. Single-wall Ti shield tests were run (thicknesses of 2.0 mm, 1.5 mm, 1.0 mm, and 0.5 mm) on Ti 15-3-3-3 material custom cut from rod stock. Hypervelocity impact (HVI) tests were used to establish the failure threshold empirically, using the additional constraint that the damage scales with impact energy, as was indicated by hydrocode simulations. The criterion for shield failure was defined as no detached spall from the shield back surface during HVI. Based on the test results, which confirmed an approximately energy-dependent shield effectiveness, the Cour-Palais equation was modified.

  6. Myocardium wall thickness transducer and measuring method

    NASA Technical Reports Server (NTRS)

    Feldstein, C.; Lewis, G. W.; Silver, R. H.; Culler, V. H. (Inventor)

    1976-01-01

    A miniature transducer for measuring changes of thickness of the myocardium is described. The device is easily implantable without traumatizing the subject, without affecting the normal muscle behavior, and is removable and implantable at a different muscle location. Operating features of the device are described.

  7. Regional Thicknesses and Thickening of Compacted and Trabeculated Myocardial Layers of the Normal Left Ventricle Studied by Cardiovascular Magnetic Resonance

    PubMed Central

    Dawson, Dana K.; Maceira, Alicia M.; Raj, Vimal J.; Graham, Catriona; Pennell, Dudley J.; Kilner, Philip J.

    2011-01-01

    Background We used cardiovascular magnetic resonance (CMR) to study normal left ventricular (LV) trabeculation as a basis for differentiation from pathological noncompaction. Methods and Results The apparent end-diastolic (ED) and end-systolic (ES) thicknesses and thickening of trabeculated and compacted myocardial layers were measured in 120 volunteers using a consistent selection of basal, mid, and apical CMR short-axis slices. All had a visible trabeculated layer in 1 or more segments. The compacted but not the trabeculated layer was thicker in men than in women (P<0.01 at ED and ES). When plotted against age, the trabeculated and compacted layer thicknesses demonstrated opposite changes: an increase of the compact layer after the fourth decade at both ED and ES (P<0.05) but a decrease of the trabeculated layer. There was age-related preservation of total wall thickness at ED but an increase at ES (P<0.05). The compacted layer thickened, whereas the trabeculated layer thinned with systole, but neither change differed between sexes. With age, the most trabeculated LV segments showed significantly greater systolic thinning of trabeculated layers and, conversely, greater thickening of the compact segments (P<0.05). Total wall thickening is neither sex nor age dependent. There were no sex differences in the trabeculated/compacted ratio at ES or ED, but the ES trabeculated/compacted ratio was smaller in older (50 to 79 years) versus younger (20 to 49 years) groups (P<0.05). Conclusions We demonstrated age- and sex-related morphometric differences in the apparent trabeculated and compacted layer thicknesses and systolic thinning of the visible trabeculated layer that contrasts with compacted myocardial wall thickening. PMID:21193690

  8. Building and degradation of secondary cell walls: are there common patterns of lamellar assembly of cellulose microfibrils and cell wall delamination?

    PubMed

    De Micco, Veronica; Ruel, Katia; Joseleau, Jean-Paul; Aronne, Giovanna

    2010-08-01

    During cell wall formation and degradation, it is possible to detect cellulose microfibrils assembled into thicker and thinner lamellar structures, respectively, following inverse parallel patterns. The aim of this study was to analyse such patterns of microfibril aggregation and cell wall delamination. The thickness of microfibrils and lamellae was measured on digital images of both growing and degrading cell walls viewed by means of transmission electron microscopy. To objectively detect, measure and classify microfibrils and lamellae into thickness classes, a method based on the application of computerized image analysis combined with graphical and statistical methods was developed. The method allowed common classes of microfibrils and lamellae in cell walls to be identified from different origins. During both the formation and degradation of cell walls, a preferential formation of structures with specific thickness was evidenced. The results obtained with the developed method allowed objective analysis of patterns of microfibril aggregation and evidenced a trend of doubling/halving lamellar structures, during cell wall formation/degradation in materials from different origin and which have undergone different treatments.

  9. Production test IP-544-A, irradiation of 1.6% enriched thick walled single tube elements in KER-1 and 2

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kratzer, W.K.; Wise, M.J.

    1962-12-12

    The objective of this production test is to authorize the irradiation of coextruded Zr-2 jacketed thick walled 1.6% enriched tubular elements in KER loops 1 and 2 to evaluate the swelling behavior of fuel elements at high uranium temperatures Coextruded Zr-2 jacketed 1.6% enriched tubular fuel elements 1.79 inch OD, 0.97 inch ID, and 12 inches long will be irradiated KER loops 1 and 2 to exposures no greater than 2500 MWD/T.

  10. High Reynolds number rough wall turbulent boundary layer experiments using Braille surfaces

    NASA Astrophysics Data System (ADS)

    Harris, Michael; Monty, Jason; Nova, Todd; Allen, James; Chong, Min

    2007-11-01

    This paper details smooth, transitional and fully rough turbulent boundary layer experiments in the New Mexico State high Reynolds number rough wall wind tunnel. The initial surface tested was generated with a Braille printer and consisted of an uniform array of Braille points. The average point height being 0.5mm, the spacing between the points in the span was 0.5mm and the surface consisted of span wise rows separated by 4mm. The wavelength to peak ratio was 8:1. The boundary layer thickness at the measurement location was 190mm giving a large separation of roughness height to layer thickness. The maximum friction velocity was uτ=1.5m/s at Rex=3.8 x10^7. Results for the skin friction co-efficient show that this surface follows a Nikuradse type inflectional curve and that Townsends outer layer similarity hypothesis is valid for rough wall flows with a large separation of scales. Mean flow and turbulence statistics will be presented.

  11. Planar measurements of spray-induced wall cooling using phosphor thermometry

    NASA Astrophysics Data System (ADS)

    Dragomirov, Plamen; Mendieta, Aldo; Abram, Christopher; Fond, Benoît; Beyrau, Frank

    2018-03-01

    The wall cooling induced by spray impingement is investigated using phosphor thermometry. Thin coatings of zinc oxide (ZnO) phosphor were applied with a transparent chemical binder onto a steel surface. Instantaneous spatially resolved temperatures were determined using the spectral intensity ratio method directly after the injection of UV-grade hexane onto the surface using a commercial gasoline injector. The investigations showed that 2D temperature measurements with high spatial and shot-to-shot precision of, respectively, 0.5 and 0.6 K can be achieved, allowing the accurate resolution of the cooling induced by the spray. The presence of a liquid film over the phosphor coating during measurements showed no noticeable influence on the measured temperatures. However, in some cases a change in the intensity ratio at the spray impingement area, in the form of a permanent "stain", could be observed after multiple injections. The formation of this stain was less likely with increasing annealing time of the coating as well as lower plate operating temperatures during the injection experiments. Finally, the experimental results indicate a noticeable influence of the thickness of the phosphor coating on the measured spray-induced wall cooling history. Hence, for quantitative analysis, a compromise between coating thickness and measurement accuracy needs to be considered for similar applications where the heat transfer rates are very high.

  12. Effect of aspect ratio on sidewall boundary-layer influence in two-dimensional airfoil testing

    NASA Technical Reports Server (NTRS)

    Murthy, A. V.

    1986-01-01

    The effect of sidewall boundary layers in airfoil testing in two-dimensional wind tunnels is investigated. The non-linear crossflow velocity variation induced because of the changes in the sidewall boundary-layer thickness is represented by the flow between a wavy wall and a straight wall. Using this flow model, a correction for the sidewall boundary-layer effects is derived in terms of the undisturbed sidewall boundary-layer properties, the test Mach number and the airfoil aspect ratio. Application of the proposed correction to available experimental data showed good correlation for the shock location and pressure distribution on airfoils.

  13. Compound Walls For Vacuum Chambers

    NASA Technical Reports Server (NTRS)

    Frazer, Robert E.

    1988-01-01

    Proposed compound-wall configuration enables construction of large high-vacuum chambers without having to use thick layers of expensive material to obtain necessary strength. Walls enclose chambers more than 1 m in diameter and several kilometers long. Compound wall made of strong outer layer of structural-steel culvert pipe welded to thin layer of high-quality, low-outgassing stainless steel.

  14. Measuring Thicknesses of Wastewater Films

    NASA Technical Reports Server (NTRS)

    Schubert, F. H.; Davenport, R. J.

    1987-01-01

    Sensor determines when thickness of film of electrically conductive wastewater on rotating evaporator drum exceeds preset value. Sensor simple electrical probe that makes contact with liquid surface. Made of materials resistant to chemicals in liquid. Mounted on shaft in rotating cylinder, liquid-thickness sensor extends toward cylinder wall so tip almost touches. Sensor body accommodates probe measuring temperature of evaporated water in cylinder.

  15. Assessment of relationships between novel inflammatory markers and presence and severity of preeclampsia: Epicardial fat thickness, pentraxin-3, and neutrophil-to-lymphocyte ratio.

    PubMed

    Cakmak, Huseyin Altug; Dincgez Cakmak, Burcu; Abide Yayla, Cigdem; Inci Coskun, Ebru; Erturk, Mehmet; Keles, Ibrahim

    2017-08-01

    The aim of this study was to evaluate the relation of three new inflammatory markers with presence and severity of preeclampsia and to compare the predictive values of all markers for presence of this setting. In this study, a total of 100 consecutive pregnants with a diagnosis of preeclampsia and 40 healthy pregnants between October 2014 and April 2015 were included. Epicardial fat tissue was calculated by two-dimensional transthoracic echocardiography, and pentraxin-3 and neutrophil-to-lymphocyte ratio were measured by using an enzyme-linked immunosorbent assay method and routine blood count analysis, respectively. Epicardial fat thickness (p < 0.001), pentraxin-3 (p < 0.001), and neutrophil-to-lymphocyte ratio (p < 0.001) were found to be significantly increased in the preeclampsia as compared to the healthy pregnants. Furthermore, epicardial fat thickness (p = 0.002), pentraxin-3 (p < 0.001), and neutrophil-to-lymphocyte ratio (p < 0.001) were significantly elevated in the severe preeclampsia compared to mild preeclampsia. In the multivariate analysis, epicardial fat thickness (p = 0.013), pentraxin-3 (p = 0.04), and neutrophil-to-lymphocyte ratio (p < 0.001) were found as significant independent predictors of presence of preeclampsia after adjusting for other risk factors. Epicardial fat thickness, neutrophil-to-lymphocyte ratio, and pentraxin-3 are important markers that provide an additional information beyond that provided by conventional methods in predicting presence and severity of preeclampsia.

  16. Visualization of the aneurysm wall: a 7.0-tesla magnetic resonance imaging study.

    PubMed

    Kleinloog, Rachel; Korkmaz, Emine; Zwanenburg, Jaco J M; Kuijf, Hugo J; Visser, Fredy; Blankena, Roos; Post, Jan A; Ruigrok, Ynte M; Luijten, Peter R; Regli, Luca; Rinkel, Gabriel J E; Verweij, Bon H

    2014-12-01

    Risk prediction of rupture of intracranial aneurysms is poor and is based mainly on lumen characteristics. However, characteristics of the aneurysm wall may be more informative predictors. The limited resolution of currently available imaging techniques and the thin aneurysm wall make imaging of wall thickness challenging. To introduce a novel protocol for imaging wall thickness variation using ultra--high-resolution 7.0-Tesla (7.0-T) magnetic resonance imaging (MRI). We studied 33 unruptured intracranial aneurysms in 24 patients with a T1-weighted 3-dimensional magnetization-prepared inversion-recovery turbo-spin-echo whole-brain sequence with a resolution of 0.8 × 0.8 × 0.8 mm. We performed a validation study with a wedge phantom and with 2 aneurysm wall biopsies obtained during aneurysm treatment using ex vivo MRI and histological examination and correlating variations in MRI signal intensity with variations in actual thickness of the aneurysm wall. In vivo, the aneurysm wall was visible in 28 of the 33 aneurysms. Variation in signal intensity was observed in all visible aneurysm walls. Ex vivo MRI showed variation in signal intensity across the wall of the biopsies, similar to that observed on the in vivo images. Signal intensity and actual thickness in both biopsies had a linear correlation, with Pearson correlation coefficients of 0.85 and 0.86. Unruptured intracranial aneurysm wall and its variation in thickness can be visualized with 7.0-T MRI. Aneurysm wall thickness variation can now be further studied as a risk factor for rupture in prospective studies.

  17. A film-based wall shear stress sensor for wall-bounded turbulent flows

    NASA Astrophysics Data System (ADS)

    Amili, Omid; Soria, Julio

    2011-07-01

    In wall-bounded turbulent flows, determination of wall shear stress is an important task. The main objective of the present work is to develop a sensor which is capable of measuring surface shear stress over an extended region applicable to wall-bounded turbulent flows. This sensor, as a direct method for measuring wall shear stress, consists of mounting a thin flexible film on the solid surface. The sensor is made of a homogeneous, isotropic, and incompressible material. The geometry and mechanical properties of the film are measured, and particles with the nominal size of 11 μm in diameter are embedded on the film's surface to act as markers. An optical technique is used to measure the film deformation caused by the flow. The film has typically deflection of less than 2% of the material thickness under maximum loading. The sensor sensitivity can be adjusted by changing the thickness of the layer or the shear modulus of the film's material. The paper reports the sensor fabrication, static and dynamic calibration procedure, and its application to a fully developed turbulent channel flow at Reynolds numbers in the range of 90,000-130,000 based on the bulk velocity and channel full height. The results are compared to alternative wall shear stress measurement methods.

  18. Does the ratio and thickness of prevertebral soft tissue provide benefit in blunt cervical spine injury?

    PubMed

    Shiau, J-P; Chin, C-C; Yeh, C-N; Chen, J-F; Lee, S-T; Fang, J-F; Liao, C-C

    2013-06-01

    Although many reports advocate computed tomography (CT) as the initial surveillance tool for occult cervical spine injury (CSI) at the emergency department (ED), the role of a lateral cervical spine radiograph (LCSX) has still not been replaced. We hypothesized that the increased width of the prevertebral soft tissue on an LCSX provides helpful information for selecting the high-risk patients who need to be evaluated with more accurate diagnostic tools. This was a retrospective and consecutive series of injured patients requiring cervical spine evaluation who were first imaged with three-view plain films at the ED. The prevertebral soft tissue thickness (PVST) and ratio of prevertebral soft tissue thickness to the cervical vertebrae diameter (PVST ratio) were calculated on the LCSX. Suspicion of CSI was confirmed by either CT or magnetic resonance imaging (MRI) scans. A total of 826 adult trauma patients requiring cervical spine evaluation were enrolled. The C3 PVST and PVST ratio were significantly different between patients with or without upper cervical area injury (UCAI, 8.64 vs. 5.49 mm, and 0.394 vs. 0.276, respectively), and, likewise, the C6 PVST and PVST ratio for patients with or without lower cervical area injury (LCAI, 16.89 vs. 14.66 mm, and 0.784 vs. 0.749, respectively). The specificity was greater than 90 % in predicting UCAI and LCAI when combining these two parameters. This method maximizes the usefulness of LCSX during the initial assessment of a conscious patient with blunt head and neck injury, especially for the identification of high-risk patients requiring prompt CT or MRI; on the other hand, it prevents the overuse of these high-cost imaging studies as initial diagnostic tools.

  19. Manufacture of thin-walled clad tubes by pressure welding of roll bonded sheets

    NASA Astrophysics Data System (ADS)

    Schmidt, Hans Christian; Grydin, Olexandr; Stolbchenko, Mykhailo; Homberg, Werner; Schaper, Mirko

    2017-10-01

    Clad tubes are commonly manufactured by fusion welding of roll bonded metal sheets or, mechanically, by hydroforming. In this work, a new approach towards the manufacture of thin-walled tubes with an outer diameter to wall thickness ratio of about 12 is investigated, involving the pressure welding of hot roll bonded aluminium-steel strips. By preparing non-welded edges during the roll bonding process, the strips can be zip-folded and (cold) pressure welded together. This process routine could be used to manufacture clad tubes in a continuous process. In order to investigate the process, sample tube sections with a wall thickness of 2.1 mm were manufactured by U-and O-bending from hot roll bonded aluminium-stainless steel strips. The forming and welding were carried out in a temperature range between RT and 400°C. It was found that, with the given geometry, a pressure weld is established at temperatures starting above 100°C. The tensile tests yield a maximum bond strength at 340°C. Micrograph images show a consistent weld of the aluminium layer over the whole tube section.

  20. Measurement of wall thickness alone does not accurately assess the presence of left ventricular hypertrophy.

    PubMed

    Leibowitz, David; Planer, David; Ben-Ibgi, Fanny; Rott, David; Weiss, A Teddy; Bursztyn, Michael

    2007-02-01

    Clinical echocardiographic assessment of left ventricular hypertrophy (LVH) is generally performed by measuring wall thickness alone (WT). The objective of this study was to compare the assessment of LVH using the measurement of WT to that using indexed LV mass. Hypertensive patients underwent echocardiography with the measurement of LV WT and LV mass. For each patient, the presence of LVH was assessed by both methods with WT compared to the gold standard of LV mass index. In all, 92 patients (51M/41F) were entered, and in only 55 patients (60%) were the two methods concordant. There was a tendency for WT to underestimate LVH in females (sensitivity 37%, specificity 79%) and overestimate LVH in males (sensitivity 88%, specificity 56%). The measurement of WT alone overestimates LVH in males and underestimates LVH in females and should not be used as a surrogate marker for increased LV mass.

  1. Impact of P/In flux ratio and epilayer thickness on faceting for nanoscale selective area growth of InP by molecular beam epitaxy.

    PubMed

    Fahed, M; Desplanque, L; Coinon, C; Troadec, D; Wallart, X

    2015-07-24

    The impact of the P/In flux ratio and the deposited thickness on the faceting of InP nanostructures selectively grown by molecular beam epitaxy (MBE) is reported. Homoepitaxial growth of InP is performed inside 200 nm wide stripe openings oriented either along a [110] or [1-10] azimuth in a 10 nm thick SiO2 film deposited on an InP(001) substrate. When varying the P/In flux ratio, no major shape differences are observed for [1-10]-oriented apertures. On the other hand, the InP nanostructure cross sections strongly evolve for [110]-oriented apertures for which (111)B facets are more prominent and (001) ones shrink for large P/In flux ratio values. These results show that the growth conditions allow tailoring the nanocrystal shape. They are discussed in the framework of the equilibrium crystal shape model using existing theoretical calculations of the surface energies of different low-index InP surfaces as a function of the phosphorus chemical potential, directly related to the P/In ratio. Experimental observations strongly suggest that the relative (111)A surface energy is probably smaller than the calculated value. We also discuss the evolution of the nanostructure shape with the InP-deposited thickness.

  2. Nasal bone length: prenasal thickness ratio: a strong 2D ultrasound marker for Down syndrome

    PubMed Central

    Szabó, Andrea; Szili, Károly; Szabó, János Tamás; Sikovanyecz, János; Isaszegi, Dóra; Horváth, Emese; Szabó, János

    2014-01-01

    Objectives To evaluate the feasibility of incorporating two-dimensional ultrasound measurements of nasal bone length (NBL) and prenasal thickness (PT) into the second-trimester anomaly scan and to determine whether the NBL : PT ratio could help in differentiating euploid and Down syndrome fetuses. Method Two-dimensional measurements of NBL and PT were obtained from the midsagittal plane of the fetal head at 14–28 weeks of gestation in a Caucasian population at risk for aneuploidy. The screening performances of NBL, PT, and the ratios NBL : PT and PT : NBL were analyzed in euploid (n = 1330) and Down syndrome (n = 33) fetuses. Results Nasal bone length and PT alone showed strong correlations with Down syndrome (sensitivity: 76% at 1.88% and 2.35% false positive rate, respectively). However, the NBL : PT ratio showed an even stronger correlation with Down syndrome (false positive rate: 0.9%, sensitivity: 97%). The mean NBL : PT ratio showed a gradual increase from 1.48 to 1.79 (a 21.2% increase) between 14 and 28 weeks of gestation. Conclusion Two-dimensional ultrasound measurements of NBL and PT, particularly the NBL : PT ratio, are highly sensitive markers for Down syndrome fetuses. © 2014 The Authors. Prenatal Diagnosis published by John Wiley & Sons, Ltd. PMID:24966049

  3. The Prediction of Unsteady Aerodynamic Loading in High Aspect Ratio Wall Bounded Jets

    NASA Astrophysics Data System (ADS)

    Lurie, Michael B.

    Stealth aircraft are becoming more and more prevalent in the aircraft industry. One of the features of many stealth aircraft is an integrated engine that is mounted above the aircraft fuselage. The engine nozzle is often rectangular with a high aspect ratio, and exhausts onto a jet deck formed by the aircraft fuselage. This configuration allows the aircraft fuselage to shield the noise and other detectable features caused by the engine from the ground. The Northrop Grumman B2 Bomber is perhaps the most well-known example of this configuration. Additionally, stealth technology combined with unmanned aerial vehicles (UAV's) has led to the Joint Unmanned Combat System project, or J-UCAS. Both of the aircraft in development in this project use a wall-bounded high aspect ratio nozzle for stealth purposes. While these engine configurations provide a low radar profile and reduce the noise levels on the ground, they do introduce additional considerations. Since the engine is mounted above the aircraft, the nozzle jet is wall bounded by the fuselage of the aircraft. This is known as the flight deck. The jet stream exiting the nozzle can travel at supersonic speeds and potentially generates shock or expansion waves that impinge on the surface of the deck. The oscillations of these shockwaves on the deck produce localized unsteady forces acting on the aircraft. In addition, the interaction between the high speed jet stream and the slower ambient air causes a shear layer to form from the trailing edge of the nozzle. Turbulent eddies form and increase in size as they move downstream. The interactions of the shear layer with the flight deck produce additional unsteady forces on the aircraft. This thesis presents a study to predict the forces on a flight deck caused by a high aspect ratio wall bounded nozzle using both experimental methods and numerical simulations. The experiments performed were conducted on two different nozzles with aspect ratios of 4-1 and 8-1. Several

  4. Relationship between macular ganglion cell complex thickness and macular outer retinal thickness: a spectral-domain optical coherence tomography study.

    PubMed

    Kita, Yoshiyuki; Kita, Ritsuko; Takeyama, Asuka; Anraku, Ayako; Tomita, Goji; Goldberg, Ivan

    2013-01-01

    To assess the relationship between macular ganglion cell complex and macular outer retinal thicknesses. Case-control study. Forty-two normal eyes and 91 eyes with primary open-angle glaucoma were studied. Spectral-domain optical coherence tomography (RTVue-100) was used to measure the macular ganglion cell complex and macular outer retinal thickness. Ganglion cell complex to outer retinal thickness ratio was also calculated. The relationships between the ganglion cell complex and outer retinal thicknesses and between the ganglion cell complex to outer retinal thickness ratio and outer retinal thickness were evaluated. There was a positive correlation between ganglion cell complex and outer retinal thicknesses in the normal group and the glaucoma group (r = 0.53, P < 0.001 and r = 0.42, P < 0.001, respectively). In that respect, there was no correlation between ganglion cell complex to outer retinal thickness ratio and outer retinal thickness in the both groups (r = -0.07, P = 0.657, and r = 0.04, P = 0.677, respectively). The ganglion cell complex to outer retinal thickness ratio was 55.65% in the normal group, 45.07% in the glaucoma group. This difference was statistically significant. The ganglion cell complex thickness may be affected by outer retinal thickness, and there is individual variation in the outer retinal thickness. Therefore, when determining the ganglion cell complex, it seems necessary to consider the outer retinal thickness as well. We propose the ratio as a suitable parameter to account for individual variations in outer retinal thickness. © 2013 The Authors. Clinical and Experimental Ophthalmology © 2013 Royal Australian and New Zealand College of Ophthalmologists.

  5. Process stability and morphology optimization of very thick 4H-SiC epitaxial layers grown by chloride-based CVD

    NASA Astrophysics Data System (ADS)

    Yazdanfar, M.; Stenberg, P.; Booker, I. D.; Ivanov, I. G.; Kordina, O.; Pedersen, H.; Janzén, E.

    2013-10-01

    The development of a chemical vapor deposition (CVD) process for very thick silicon carbide (SiC) epitaxial layers suitable for high power devices is demonstrated by epitaxial growth of 200 μm thick, low doped 4H-SiC layers with excellent morphology at growth rates exceeding 100 μm/h. The process development was done in a hot wall CVD reactor without rotation using both SiCl4 and SiH4+HCl precursor approaches to chloride based growth chemistry. A C/Si ratio <1 and an optimized in-situ etch are shown to be the key parameters to achieve 200 μm thick, low doped epitaxial layers with excellent morphology.

  6. Influence of radiation dose and reconstruction algorithm in MDCT assessment of airway wall thickness: A phantom study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gomez-Cardona, Daniel; Nagle, Scott K.; Department of Radiology, University of Wisconsin-Madison School of Medicine and Public Health, 600 Highland Avenue, Madison, Wisconsin 53792

    Purpose: Wall thickness (WT) is an airway feature of great interest for the assessment of morphological changes in the lung parenchyma. Multidetector computed tomography (MDCT) has recently been used to evaluate airway WT, but the potential risk of radiation-induced carcinogenesis—particularly in younger patients—might limit a wider use of this imaging method in clinical practice. The recent commercial implementation of the statistical model-based iterative reconstruction (MBIR) algorithm, instead of the conventional filtered back projection (FBP) algorithm, has enabled considerable radiation dose reduction in many other clinical applications of MDCT. The purpose of this work was to study the impact of radiationmore » dose and MBIR in the MDCT assessment of airway WT. Methods: An airway phantom was scanned using a clinical MDCT system (Discovery CT750 HD, GE Healthcare) at 4 kV levels and 5 mAs levels. Both FBP and a commercial implementation of MBIR (Veo{sup TM}, GE Healthcare) were used to reconstruct CT images of the airways. For each kV–mAs combination and each reconstruction algorithm, the contrast-to-noise ratio (CNR) of the airways was measured, and the WT of each airway was measured and compared with the nominal value; the relative bias and the angular standard deviation in the measured WT were calculated. For each airway and reconstruction algorithm, the overall performance of WT quantification across all of the 20 kV–mAs combinations was quantified by the sum of squares (SSQs) of the difference between the measured and nominal WT values. Finally, the particular kV–mAs combination and reconstruction algorithm that minimized radiation dose while still achieving a reference WT quantification accuracy level was chosen as the optimal acquisition and reconstruction settings. Results: The wall thicknesses of seven airways of different sizes were analyzed in the study. Compared with FBP, MBIR improved the CNR of the airways, particularly at low

  7. Aspect ratios and magma overpressures of non-feeder dikes observed in the Miyake-jima volcano (Japan), and fracture toughness of its upper part

    NASA Astrophysics Data System (ADS)

    Kusumoto, Shigekazu; Geshi, Nobuo; Gudmundsson, Agust

    2013-03-01

    present a new method for estimating the length and maximum thickness (aperture) of a dike from the observed opening at one dike tip. We apply the method to 15 arrested non-feeder dikes (where the upper tip is known, the lower tip unknown) in the caldera walls of Miyake-jima, Japan, to estimate the length-thickness ratio, as well as the magma overpressure and fracture toughness. The calculated length-thickness ratio ranges from 61 to 246, with an average of 136. The ratios are low because the dikes are emplaced close to the surface in comparatively compliant (soft) rocks. Using these ratios and the appropriate elastic constants, the calculated magmatic overpressures of the dikes are between 2.3 and 8.9 MPa, and the stress intensity factors between 38 and 117 MPa m1/2. All these values are within the range of typical in situ estimates, supporting the validity of this new method.

  8. Sensitivity of the downward to sweeping velocity ratio to the bypass flow percentage along a guide wall for downstream fish passage

    USGS Publications Warehouse

    Mulligan, Kevin; Towler, Brett; Haro, Alexander J.; Ahlfeld, David P.

    2017-01-01

    Partial-depth impermeable guidance structures (or guide walls) are used as a method to assist in the downstream passage of fish at a hydroelectric facility. However, guide walls can result in a strong downward velocity causing the approaching fish to pass below the wall and into the direction of the turbine intakes. The objective of this study was to describe how the ratio of the vertical velocity to the sweeping velocity magnitude changes along the full length and depth of a guide wall under a wide range of bypass flow percentages within a power canal. This paper focused on two guide wall configurations, each set at an angle of 45 ° to the approaching flow field and at a depth of 10 and 20 ft (3.05 and 6.10 m). The hydraulic conditions upstream of each guide wall configuration were shown to be impacted by a change in the bypass flow percentage, not only near the bypass but also at upstream sections of the guide wall. Furthermore, the effect of changing the bypass flow percentage was similar for both guide wall depths. In both cases, the effect of increasing the bypass flow percentage was magnified closer to the bypass and deeper in the water column along the guide wall.

  9. Attenuation of radiation from distributed gamma sources as a function of wall thickness of a concrete blockhouse

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schmoke, M. A.; Rexroad, R. E.; Tiller, H. J.

    1963-06-15

    The experiment described constitutes part of the shielding program conducted by Army Nuclear Defense Laboratory and was designed to experimentally verify theoretical calculations used to predict the amount of radiation protection afforded by above-ground structures in a fallout radiation field. This method requires the knowledge of some physical parameters of a structure such as mass thickness of the walls and the geometric orientation of the detectors within the structure. From this information, a reduction factor for any given structure may be calculated. This Laboratory's experimental program was initially begun by measuring the attenuation of a simple structure with no complicatingmore » internal or external geometries and will proceed to more complex structures with basements, interior partitions, and upper floors. (auth)« less

  10. Human Uterine Wall Tension Trajectories and the Onset of Parturition

    PubMed Central

    Sokolowski, Peter; Saison, Francis; Giles, Warwick; McGrath, Shaun; Smith, David; Smith, Julia; Smith, Roger

    2010-01-01

    Uterine wall tension is thought to be an important determinant of the onset of labor in pregnant women. We characterize human uterine wall tension using ultrasound from the second trimester of pregnancy until parturition and compare preterm, term and twin pregnancies. A total of 320 pregnant women were followed from first antenatal visit to delivery during the period 2000–2004 at the John Hunter Hospital, NSW, Australia. The uterine wall thickness, length, anterior-posterior diameter and transverse diameter were determined by serial ultrasounds. Subjects were divided into three groups: women with singleton pregnancies and spontaneous labor onset, either preterm or term and women with twin pregnancies. Intrauterine pressure results from the literature were combined with our data to form trajectories for uterine wall thickness, volume and tension for each woman using the prolate ellipsoid method and the groups were compared at 20, 25 and 30 weeks gestation. Uterine wall tension followed an exponential curve, with results increasing throughout pregnancy with the site of maximum tension on the anterior wall. For those delivering preterm, uterine wall thickness was increased compared with term. For twin pregnancies intrauterine volume was increased compared to singletons (), but wall thickness was not. There was no evidence for increased tension in those delivering preterm or those with twin gestations. These data are not consistent with a role for high uterine wall tension as a causal factor in preterm spontaneous labor in singleton or twin gestations. It seems likely that hormonal differences in multiple gestations are responsible for increased rates of preterm birth in this group rather than increased tension. PMID:20585649

  11. Nasal bone length: prenasal thickness ratio: a strong 2D ultrasound marker for Down syndrome.

    PubMed

    Szabó, Andrea; Szili, Károly; Szabó, János Tamás; Sikovanyecz, János; Isaszegi, Dóra; Horváth, Emese; Szabó, János

    2014-12-01

    To evaluate the feasibility of incorporating two-dimensional ultrasound measurements of nasal bone length (NBL) and prenasal thickness (PT) into the second-trimester anomaly scan and to determine whether the NBL : PT ratio could help in differentiating euploid and Down syndrome fetuses. Two-dimensional measurements of NBL and PT were obtained from the midsagittal plane of the fetal head at 14-28 weeks of gestation in a Caucasian population at risk for aneuploidy. The screening performances of NBL, PT, and the ratios NBL : PT and PT : NBL were analyzed in euploid (n = 1330) and Down syndrome (n = 33) fetuses. Nasal bone length and PT alone showed strong correlations with Down syndrome (sensitivity: 76% at 1.88% and 2.35% false positive rate, respectively). However, the NBL : PT ratio showed an even stronger correlation with Down syndrome (false positive rate: 0.9%, sensitivity: 97%). The mean NBL : PT ratio showed a gradual increase from 1.48 to 1.79 (a 21.2% increase) between 14 and 28 weeks of gestation. Two-dimensional ultrasound measurements of NBL and PT, particularly the NBL : PT ratio, are highly sensitive markers for Down syndrome fetuses. © 2014 John Wiley & Sons, Ltd.

  12. High Rayleigh number convection in rectangular enclosures with differentially heated vertical walls and aspect ratios between zero and unity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kassemi, S.A.

    1988-04-01

    High Rayleigh number convection in a rectangular cavity with insulated horizontal surfaces and differentially heated vertical walls was analyzed for an arbitrary aspect ratio smaller than or equal to unity. Unlike previous analytical studies, a systematic method of solution based on linearization technique and analytical iteration procedure was developed to obtain approximate closed-form solutions for a wide range of aspect ratios. The predicted velocity and temperature fields are shown to be in excellent agreement with available experimental and numerical data.

  13. High Rayleigh number convection in rectangular enclosures with differentially heated vertical walls and aspect ratios between zero and unity

    NASA Technical Reports Server (NTRS)

    Kassemi, Siavash A.

    1988-01-01

    High Rayleigh number convection in a rectangular cavity with insulated horizontal surfaces and differentially heated vertical walls was analyzed for an arbitrary aspect ratio smaller than or equal to unity. Unlike previous analytical studies, a systematic method of solution based on linearization technique and analytical iteration procedure was developed to obtain approximate closed-form solutions for a wide range of aspect ratios. The predicted velocity and temperature fields are shown to be in excellent agreement with available experimental and numerical data.

  14. Antarctic ice sheet thickness estimation using the horizontal-to-vertical spectral ratio method with single-station seismic ambient noise

    NASA Astrophysics Data System (ADS)

    Yan, Peng; Li, Zhiwei; Li, Fei; Yang, Yuande; Hao, Weifeng; Bao, Feng

    2018-03-01

    We report on a successful application of the horizontal-to-vertical spectral ratio (H / V) method, generally used to investigate the subsurface velocity structures of the shallow crust, to estimate the Antarctic ice sheet thickness for the first time. Using three-component, five-day long, seismic ambient noise records gathered from more than 60 temporary seismic stations located on the Antarctic ice sheet, the ice thickness measured at each station has comparable accuracy to the Bedmap2 database. Preliminary analysis revealed that 60 out of 65 seismic stations on the ice sheet obtained clear peak frequencies (f0) related to the ice sheet thickness in the H / V spectrum. Thus, assuming that the isotropic ice layer lies atop a high velocity half-space bedrock, the ice sheet thickness can be calculated by a simple approximation formula. About half of the calculated ice sheet thicknesses were consistent with the Bedmap2 ice thickness values. To further improve the reliability of ice thickness measurements, two-type models were built to fit the observed H / V spectrum through non-linear inversion. The two-type models represent the isotropic structures of single- and two-layer ice sheets, and the latter depicts the non-uniform, layered characteristics of the ice sheet widely distributed in Antarctica. The inversion results suggest that the ice thicknesses derived from the two-layer ice models were in good concurrence with the Bedmap2 ice thickness database, and that ice thickness differences between the two were within 300 m at almost all stations. Our results support previous finding that the Antarctic ice sheet is stratified. Extensive data processing indicates that the time length of seismic ambient noise records can be shortened to two hours for reliable ice sheet thickness estimation using the H / V method. This study extends the application fields of the H / V method and provides an effective and independent way to measure ice sheet thickness in Antarctica.

  15. Wood formation from the base to the crown in Pinus radiata: gradients of tracheid wall thickness, wood density, radial growth rate and gene expression

    Treesearch

    Sheree Cato; Lisa McMillan; Lloyd Donaldson; Thomas Richardson; Craig Echt; Richard Gardner

    2006-01-01

    Wood formation was investigated at five heights along the bole for two unrelated trees of Pinus radiataBoth trees showed clear gradients in wood properties from the base to the crown. Cambial cells at the base of the tree were dividing 3.3-fold slower than those at the crown, while the average thickness of cell walls in wood was highest at the base....

  16. Research on wall shear stress considering wall roughness when shear swirling flow vibration cementing

    NASA Astrophysics Data System (ADS)

    Cui, Zhihua; Ai, Chi; Feng, Fuping

    2017-01-01

    When shear swirling flow vibration cementing, the casing is revolving periodically and eccentrically, which leads to the annulus fluid in turbulent swirling flow state. The wall shear stress is more than that in laminar flow field when conventional cementing. The paper mainly studied the wall shear stress distribution on the borehole wall when shear swirling flow vibration cementing based on the finite volume method. At the same time, the wall roughness affected and changed the turbulent flow near the borehole wall and the wall shear stress. Based on the wall function method, the paper established boundary conditions considering the wall roughness and derived the formula of the wall shear stress. The results showed that the wall roughness significantly increases the wall shear stress. However, the larger the wall roughness, the greater the thickness of mud cake, which weakening the cementing strength. Considering the effects in a comprehensive way, it is discovered that the particle size of solid phase in drilling fluid is about 0.1 mm to get better cementing quality.

  17. Rotational stabilization of the resistive wall modes in tokamaks with a ferritic wall

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pustovitov, V. D.; National Research Nuclear University “MEPhI,” Kashirskoe sh. 31, Moscow 115409; Yanovskiy, V. V.

    The dynamics of the rotating resistive wall modes (RWMs) is analyzed in the presence of a uniform ferromagnetic resistive wall with μ{sup ^}≡μ/μ{sub 0}≤4 (μ is the wall magnetic permeability, and μ{sub 0} is the vacuum one). This mimics a possible arrangement in ITER with ferromagnetic steel in test blanket modules or in future experiments in JT-60SA tokamak [Y. Kamada, P. Barabaschi, S. Ishida, the JT-60SA Team, and JT-60SA Research Plan Contributors, Nucl. Fusion 53, 104010 (2013)]. The earlier studies predict that such a wall must provide a destabilizing influence on the plasma by reducing the beta limit and increasingmore » the growth rates, compared to the reference case with μ{sup ^}=1. This is true for the locked modes, but the presented results show that the mode rotation changes the tendency to the opposite. At μ{sup ^}>1, the rotational stabilization related to the energy sink in the wall becomes even stronger than at μ{sup ^}=1, and this “external” effect develops at lower rotation frequency, estimated as several kHz at realistic conditions. The study is based on the cylindrical dispersion relation valid for arbitrary growth rates and frequencies. This relation is solved numerically, and the solutions are compared with analytical dependences obtained for slow (s/d{sub w}≫1) and fast (s/d{sub w}≪1) “ferromagnetic” rotating RWMs, where s is the skin depth and d{sub w} is the wall thickness. It is found that the standard thin-wall modeling becomes progressively less reliable at larger μ{sup ^}, and the wall should be treated as magnetically thick. The analysis is performed assuming only a linear plasma response to external perturbations without constraints on the plasma current and pressure profiles.« less

  18. Effects of aspect ratio of multi-walled carbon nanotubes on coal washery waste water treatment.

    PubMed

    Aliyu, Ahmed; Kariim, Ishaq; Abdulkareem, Saka Ambali

    2017-11-01

    The dependency of adsorption behaviour on the aspect ratio of multi-walled carbon nanotubes (MWCNTs) has been explored. In this study, effect of growth temperature on yield and aspect ratio of MWCNTs by catalytic chemical vapour deposition (CCVD) method is reported. The result revealed that yield and aspect ratio of synthesised MWCNTs strongly depend on the growth temperature during CCVD operation. The resulting MWCNTs were characterized by High Resolution Transmission Electron Microscope (HRTEM), Dynamic Light Scattering (DLS) and X-ray diffraction (XRD) techniques to determine it diameter, hydrodynamic diameter and crystallinity respectively. Aspect ratio and length of the grown MWCNTs were determined from the HRTEM images with the hydrodynamic diameter using the modified Navier-Stokes and Stokes-Einstein equations. The effect of the prepared MWCNTs dosage were investigated on the Turbidity, Iron (Fe) and Lead (Pb) removal efficiency of coal washery effluent. The MWCNTs with higher length (58.17 μm) and diameter (71 nm) tend to show high turbidity and Fe removal, while MWCNTs with lower length (38.87 μm) and diameter (45 nm) tend to show high removal of Pb. Hence, the growth temperature during CCVD operation shows a great effluence on the aspect ratio of MWCNTs which determines it area of applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Mathematical Model of Stress-Strain State of Curved Tube of Non-Circular Cross-Section with Account of Technological Wall Thickness Variation

    NASA Astrophysics Data System (ADS)

    Pirogov, S. P.; Ustinov, N. N.; Smolin, N. I.

    2018-05-01

    A mathematical model of the stress-strain state of a curved tube of a non-circular cross-section is presented, taking into account the technological wall thickness variation. On the basis of the semi-membrane shell theory, a system of linear differential equations describing the deformation of a tube under the effect of pressure is obtained. To solve the boundary value problem, the method of shooting is applied. The adequacy of the proposed mathematical model is verified by comparison with the experimental data and the results of the calculation of tubes by the energy method.

  20. Evaluation of Building Energy Saving Through the Development of Venetian Blinds' Optimal Control Algorithm According to the Orientation and Window-to-Wall Ratio

    NASA Astrophysics Data System (ADS)

    Kwon, Hyuk Ju; Yeon, Sang Hun; Lee, Keum Ho; Lee, Kwang Ho

    2018-02-01

    As various studies focusing on building energy saving have been continuously conducted, studies utilizing renewable energy sources, instead of fossil fuel, are needed. In particular, studies regarding solar energy are being carried out in the field of building science; in order to utilize such solar energy effectively, solar radiation being brought into the indoors should be acquired and blocked properly. Blinds are a typical solar radiation control device that is capable of controlling indoor thermal and light environments. However, slat-type blinds are manually controlled, giving a negative effect on building energy saving. In this regard, studies regarding the automatic control of slat-type blinds have been carried out for the last couple of decades. Therefore, this study aims to provide preliminary data for optimal control research through the controlling of slat angle in slat-type blinds by comprehensively considering various input variables. The window area ratio and orientation were selected as input variables. It was found that an optimal control algorithm was different among each window-to-wall ratio and window orientation. In addition, through comparing and analyzing the building energy saving performance for each condition by applying the developed algorithms to simulations, up to 20.7 % energy saving was shown in the cooling period and up to 12.3 % energy saving was shown in the heating period. In addition, building energy saving effect was greater as the window area ratio increased given the same orientation, and the effects of window-to-wall ratio in the cooling period were higher than those of window-to-wall ratio in the heating period.

  1. RADIOAUTOGRAPHIC STUDY OF CELL WALL DEPOSITION IN GROWING PLANT CELLS

    PubMed Central

    Ray, Peter M.

    1967-01-01

    Segments cut from growing oat coleoptiles and pea stems were fed glucose-3H in presence and absence of the growth hormone indoleacetic acid (IAA). By means of electron microscope radioautography it was demonstrated that new cell wall material is deposited both at the wall surface (apposition) and within the preexisting wall structure (internally). Quantitative profiles for the distribution of incorporation with position through the thickness of the wall were obtained for the thick outer wall of epidermal cells. With both oat coleoptile and pea stem epidermal outer walls, it was found that a larger proportion of the newly synthesized wall material appeared to become incorporated within the wall in the presence of IAA. Extraction experiments on coleoptile tissue showed that activity that had been incorporated into the cell wall interior represented noncellulosic constituents, mainly hemicelluloses, whereas cellulose was deposited largely or entirely by apposition. It seems possible that internal incorporation of hemicelluloses plays a role in the cell wall expansion process that is involved in cell growth. PMID:6064369

  2. Effects of spaceflight on polysaccharides of Saccharomyces cerevisiae cell wall.

    PubMed

    Liu, Hong-Zhi; Wang, Qiang; Liu, Xiao-Yong; Tan, Sze-Sze

    2008-12-01

    Freeze-dried samples of four Saccharomyces cerevisiae strains, namely, FL01, FL03, 2.0016, and 2.1424, were subjected to spaceflight. After the satellite's landing on Earth, the samples were recovered and changes in yeast cell wall were analyzed. Spaceflight strains of all S. cerevisiae strains showed significant changes in cell wall thickness (P < 0.05). One mutant of S. cerevisiae 2.0016 with increased biomass, cell wall thickness, and cell wall glucan was isolated (P < 0.05). The spaceflight mutant of S. cerevisiae 2.0016 showed 46.7%, 62.6%, and 146.0% increment in biomass, cell wall thickness and beta-glucan content, respectively, when compared to the ground strain. Moreover, growth curve analysis showed spaceflight S. cerevisiae 2.0016 had a faster growth rate, shorter lag phase periods, higher final biomass, and higher content of beta-glucan. Genetic stability analysis showed that prolonged subculturing of spaceflight strain S. cerevisiae 2.0016 did not lead to the appearance of variants, indicating that the genetic stability of S. cerevisiae 2.0016 mutant could be sufficient for its exploitation of beta-glucan production.

  3. Direct measurement of wall slip and slip layer thickness of non-Brownian hard-sphere suspensions in rectangular channel flows

    NASA Astrophysics Data System (ADS)

    Jesinghausen, Steffen; Weiffen, Rene; Schmid, Hans-Joachim

    2016-09-01

    Wall slip is a long-known phenomenon in the field of rheology. Nevertheless, the origin and the evolution are not completely clear yet. Regarding suspensions, the effect becomes even more complicated, because different mechanisms like pure slip or slip due to particle migration have to be taken into account. Furthermore, suspensions themselves show many flow anomalies and the isolation of slip is complicated. In order to develop working physical models, further insight is necessary. In this work, we measured experimentally the wall slip velocities of different highly filled suspensions in a rectangular slit die directly with respect to the particle concentration and the particle size. The slip velocities were obtained using a particle image velocimetry (PIV) system. The suspensions consisting of a castor oil-cinnamon oil blend and PMMA particles were matched in terms of refractive indexes to appear transparent. Hereby, possible optical path lengths larger than 15 mm were achieved. The slip velocities were found to be in a quadratic relation to the wall shear stress. Furthermore, the overall flow rate as well as the particle concentration has a direct influence on the slip. Concerning the shear stress, there seem to be two regions of slip with different physical characteristics. Furthermore, we estimated the slip layer thickness directly from the velocity profiles and propose a new interpretation. The PIV technique is used to investigate the viscosity and implicit the concentration profile in the slit die. It is shown that the particle migration process is quite fast.

  4. Graphical determination of wall temperatures for heat transfers through walls of arbitrary shape

    NASA Technical Reports Server (NTRS)

    Lutz, Otto

    1950-01-01

    A graphical method is given which permits determining of the temperature distribution during heat transfer in arbitrarily shaped walls. Three examples show the application of the method. The further development of heat engines depends to a great extent on the control of the thermal stresses in the walls. The thermal stresses stem from the nonuniform temperature distribution in heat transfer through walls which are, for structural reasons, of various thicknesses and sometimes complicated shape. Thus, it is important to know the temperature distribution in these structural parts. Following, a method is given which permits solution of this problem.

  5. Free and Forced Vibrations of Thick-Walled Anisotropic Cylindrical Shells

    NASA Astrophysics Data System (ADS)

    Marchuk, A. V.; Gnedash, S. V.; Levkovskii, S. A.

    2017-03-01

    Two approaches to studying the free and forced axisymmetric vibrations of cylindrical shell are proposed. They are based on the three-dimensional theory of elasticity and division of the original cylindrical shell with concentric cross-sectional circles into several coaxial cylindrical shells. One approach uses linear polynomials to approximate functions defined in plan and across the thickness. The other approach also uses linear polynomials to approximate functions defined in plan, but their variation with thickness is described by the analytical solution of a system of differential equations. Both approaches have approximation and arithmetic errors. When determining the natural frequencies by the semi-analytical finite-element method in combination with the divide and conqure method, it is convenient to find the initial frequencies by the finite-element method. The behavior of the shell during free and forced vibrations is analyzed in the case where the loading area is half the shell thickness

  6. The impact of different multi-walled carbon nanotubes on the X-band microwave absorption of their epoxy nanocomposites.

    PubMed

    Che, Bien Dong; Nguyen, Bao Quoc; Nguyen, Le-Thu T; Nguyen, Ha Tran; Nguyen, Viet Quoc; Van Le, Thang; Nguyen, Nieu Huu

    2015-01-01

    Carbon nanotube (CNT) characteristics, besides the processing conditions, can change significantly the microwave absorption behavior of CNT/polymer composites. In this study, we investigated the influence of three commercial multi-walled CNT materials with various diameters and length-to-diameter aspect ratios on the X-band microwave absorption of epoxy nanocomposites with CNT contents from 0.125 to 2 wt%, prepared by two dispersion methods, i.e. in solution with surfactant-aiding and via ball-milling. The laser diffraction particle size and TEM analysis showed that both methods produced good dispersions at the microscopic level of CNTs. Both a high aspect ratio resulting in nanotube alignment trend and good infiltration of the matrix in the individual nanotubes, which was indicated by high Brookfield viscosities at low CNT contents of CNT/epoxy dispersions, are important factors to achieve composites with high microwave absorption characteristics. The multi-walled carbon nanotube (MWCNT) with the largest aspect ratio resulted in composites with the best X-band microwave absorption performance, which is considerably better than that of reported pristine CNT/polymer composites with similar or lower thicknesses and CNT loadings below 4 wt%. A high aspect ratio of CNTs resulting in microscopic alignment trend of nanotubes as well as a good level of micro-scale CNT dispersion resulting from good CNT-matrix interactions are crucial to obtain effective microwave absorption performance. This study demonstrated that effective radar absorbing MWCNT/epoxy nanocomposites having small matching thicknesses of 2-3 mm and very low filler contents of 0.25-0.5 wt%, with microwave energy absorption in the X-band region above 90% and maximum absorption peak values above 97%, could be obtained via simple processing methods, which is promising for mass production in industrial applications. Graphical AbstractComparison of the X-band microwave reflection loss of epoxy composites of

  7. Gortler vortices and transition in wall boundary layers of two Mach 5 nozzles

    NASA Technical Reports Server (NTRS)

    Beckwith, I. E.; Holley, B. B.

    1981-01-01

    The onset of transition in the wall boundary layers of two axisymmetric Mach 5 wind-tunnel nozzles has been measured under conditions of extremely low incident disturbance levels. The range of test unit Reynolds numbers, based on conditions at the nozzle exit, was from 6 x 10 to the 6th power m to 2.5 x 10 to the 7th power m. When the nozzle walls were maintained in a polished and clean condition, transition moved gradually upstream as the test Reynolds number was increased. When transition occurred in the supersonic concave wall region, the values of the local Gortler parameter at transition varied from about 5 to 6, whereas the momentum thickness Reynolds number varied from about 750 to 1050. Oil flow patterns obtained near the exit of the nozzles indicated that Gortler vortices were always present when the wall boundary layers were laminar. Calculations for the growth of Gortler vortices based on new results from linear theory for supersonic flat-plate profiles gave amplification ratios to transition from e to the 4th power to e to the 15th power. Possible reasons for this wide range in amplification ratios are discussed, but no definite conclusions are yet possible regarding the values of n in a simple e to the nth power type theory for the assumed linear amplification of Gortler vortices to transition in supersonic nozzles.

  8. Microsurgical Chest Wall Reconstruction After Oncologic Resections

    PubMed Central

    Sauerbier, Michael; Dittler, S.; Kreutzer, C.

    2011-01-01

    Defect reconstruction after radical oncologic resection of malignant chest wall tumors requires adequate soft tissue reconstruction with function, stability, integrity, and an aesthetically acceptable result of the chest wall. The purpose of this article is to describe possible reconstructive microsurgical pathways after full-thickness oncologic resections of the chest wall. Several reliable free flaps are described, and morbidity and mortality rates of patients are discussed. PMID:22294944

  9. Ultrasound bladder wall thickness measurement in diagnosis of recurrent urinary tract infections and cystitis cystica in prepubertal girls.

    PubMed

    Milošević, Danko; Trkulja, Vladimir; Turudić, Daniel; Batinić, Danica; Spajić, Borislav; Tešović, Goran

    2013-12-01

    To evaluate urinary bladder wall thickness (BWT) assessed by ultrasound as a diagnostic tool for cystitis cystica. This was a 9-year prospective study comprising 120 prepubertal girls. Sixty subjects of whom half underwent cystoscopy represented cases while the other 60 (those with a single urinary tract infection and healthy subjects) represented controls. Based on receiver operating characteristics (ROC) analysis, BWT discriminated very well between cases and controls with area under the ROC curve close to 1.0. At the optimum cut-off defined at 3.9 mm, negative predictive value (NPV) was 100% leaving no probability of cystic cystitis with BWT <3.9 mm. Positive predictive value (PPV) was also very high (95.2%), indicating only around 4.82% probability of no cystic cystitis in patients with BWT values ≥3.9 mm. BWT could also distinguish between healthy subjects and those with a cured single urinary tract infection, although discriminatory properties were moderate (area under ROC 86.7%, PPV 78.8%, NPV 85.2%). Ultrasound mucosal bladder wall measurement is a non-invasive, simple and quite reliable method in diagnosis of cystitis cystica in prepubertal girls with recurrent urinary tract infections. Copyright © 2013 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

  10. A thick-walled sphere rotating in a uniform magnetic field: The next step to de-spin a space object

    NASA Astrophysics Data System (ADS)

    Nurge, Mark A.; Youngquist, Robert C.; Caracciolo, Ryan A.; Peck, Mason; Leve, Frederick A.

    2017-08-01

    Modeling the interaction between a moving conductor and a static magnetic field is critical to understanding the operation of induction motors, eddy current braking, and the dynamics of satellites moving through Earth's magnetic field. Here, we develop the case of a thick-walled sphere rotating in a uniform magnetic field, which is the simplest, non-trivial, magneto-statics problem that leads to complete closed-form expressions for the resulting potentials, fields, and currents. This solution requires knowledge of all of Maxwell's time independent equations, scalar and vector potential equations, and the Lorentz force law. The paper presents four cases and their associated experimental results, making this topic appropriate for an advanced student lab project.

  11. An ultrasonographic evaluation of skin thickness in breast cancer patients after postmastectomy radiation therapy

    PubMed Central

    2011-01-01

    Background To determine the usefulness of ultrasonography in the assessment of post radiotherapy skin changes in postmastectomy breast cancer patients. Methods Patients treated for postmastectomy radiotherapy in National University Hospital (NUH) and Tan Tock Seng Hospital (TTSH), Singapore between January 2004- December 2005 was recruited retrospectively. Ultrasound scan was performed on these Asian patients who had been treated to a total dose of 46-50 Gy with 1 cm bolus placed on the skin. The ultrasound scans were performed blinded to the RTOG scores, and the skin thickness of the individually marked points on the irradiated chest wall was compared to the corresponding points on the non-irradiated breast. Results The mean total skin thickness inclusive of the epidermis and the dermis of the right irradiated chest wall was 0.1712 mm (± 0.03392 mm) compared with the contra-lateral non-irradiated breast which was 0.1845 mm (± 0.04089 mm; p = 0.007). The left irradiated chest wall had a mean skin thickness of 0.1764 mm (± 0.03184 mm) compared with the right non-irradiated breast which was 0.1835 mm (± 0.02584 mm; p = 0.025). These independent t-tests produced a significant difference of reduced skin thickness on the right irradiated chest wall, p = 0.007 (p < 0.05) and left irradiated chest wall p = 0.025 (p < 0.025) in comparison to the non-irradiated skin thickness investigating chronic skin reactions. Patients with grade 2 acute skin toxicity presented with thinner skin as compared to patients with grade 1 (p = 0.006). Conclusions This study has shown that there is a statistically significant difference between the skin thicknesses of the irradiated chest wall and the contra-lateral non-irradiated breast and a predisposition to chronic reactions was found in patients with acute RTOG scoring of grade1 and grade 2. PMID:21261940

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  13. Measurement of defect thickness of the wall thinning defect pipes by lock-in infrared thermography technique

    NASA Astrophysics Data System (ADS)

    Kim, Kyeongsuk; Kim, Kyungsu; Jung, Hyunchul; Chang, Hosub

    2010-03-01

    Mostly piping which is using for the nuclear power plants are made up of carbon steel pipes. The wall thinning defects occurs by the effect of the flow accelerated corrosion of fluid that flows in carbon steel pipes. The defects could be found on the welding part and anywhere in the pipes. The infrared thermography technique which is one of the non-destructive testing method has used for detecting the defects of various kinds of materials over the years. There is a limitation for measuring the defect of metals that have a big coefficient of thermal diffusion. However, a technique using lock-in method gets over the difficulty. Consequently, the lock-in infrared thermography technique has been applied to the various industry fields. In this paper, the defect thickness of the straight pipe which has an artificial defect the inside of the pipes was measured by using the lock-in infrared thermography technique and the result could be utilized in detecting defects of carbon steel pipes.

  14. Variation among northern red oak provenances in bark thickness:dbh ratios

    Treesearch

    Matthew S. Russell; Jeffrey O. Dawson

    1995-01-01

    Differences in bark thickness in relation to diameter at breast height were observed in a 30-32 year old Illinois planting of 32 provenances of northern red oak (Quercus rubra) from throughout its natural range. Bark thickness by itself is often a good indication of relative cambial insulation from fire. Fire resistance in trees can largely be...

  15. Nucleation and growth of single layer graphene on electrodeposited Cu by cold wall chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Das, Shantanu; Drucker, Jeff

    2017-03-01

    The nucleation density and average size of graphene crystallites grown using cold wall chemical vapor deposition (CVD) on 4 μm thick Cu films electrodeposited on W substrates can be tuned by varying growth parameters. Growth at a fixed substrate temperature of 1000 °C and total pressure of 700 Torr using Ar, H2 and CH4 mixtures enabled the contribution of total flow rate, CH4:H2 ratio and dilution of the CH4/H2 mixture by Ar to be identified. The largest variation in nucleation density was obtained by varying the CH4:H2 ratio. The observed morphological changes are analogous to those that would be expected if the deposition rate were varied at fixed substrate temperature for physical deposition using thermal evaporation. The graphene crystallite boundary morphology progresses from irregular/jagged through convex hexagonal to regular hexagonal as the effective C deposition rate decreases. This observation suggests that edge diffusion of C atoms along the crystallite boundaries, in addition to H2 etching, may contribute to shape evolution of the graphene crystallites. These results demonstrate that graphene grown using cold wall CVD follows a nucleation and growth mechanism similar to hot wall CVD. As a consequence, the vast knowledge base relevant to hot wall CVD may be exploited for graphene synthesis by the industrially preferable cold wall method.

  16. Measure Guideline: Incorporating Thick Layers of Exterior Rigid Insulation on Walls

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lstiburek, Joseph; Baker, Peter

    This measure guideline provides information about the design and construction of wall assemblies that use layers of rigid exterior insulation thicker than 1-½ inches and that require a secondary cladding attachment location exterior to the insulation. The guideline is separated into several distinct sections that cover: fundamental building science principles relating to the use of exterior insulation on wall assemblies; design principles for tailoring this use to the specific project goals and requirements; and construction detailing to increase understanding about implementing the various design elements.

  17. Lamb mode selection for accurate wall loss estimation via guided wave tomography

    NASA Astrophysics Data System (ADS)

    Huthwaite, P.; Ribichini, R.; Lowe, M. J. S.; Cawley, P.

    2014-02-01

    Guided wave tomography offers a method to accurately quantify wall thickness losses in pipes and vessels caused by corrosion. This is achieved using ultrasonic waves transmitted over distances of approximately 1-2m, which are measured by an array of transducers and then used to reconstruct a map of wall thickness throughout the inspected region. To achieve accurate estimations of remnant wall thickness, it is vital that a suitable Lamb mode is chosen. This paper presents a detailed evaluation of the fundamental modes, S0 and A0, which are of primary interest in guided wave tomography thickness estimates since the higher order modes do not exist at all thicknesses, to compare their performance using both numerical and experimental data while considering a range of challenging phenomena. The sensitivity of A0 to thickness variations was shown to be superior to S0, however, the attenuation from A0 when a liquid loading was present was much higher than S0. A0 was less sensitive to the presence of coatings on the surface of than S0.

  18. Construction Guide to Next-Generation High-Performance Walls in Climate Zones 3-5 - Part 2: 2x4 Walls

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kochkin, V.; Wiehagen, J.

    2017-06-01

    Part 2 of this Construction Guide to High-Performance Walls in Climate Zones 3-5 provides straightforward and cost-effective strategies to construct durable, energy-efficient walls. It addresses walls constructed with 2x4 wood frame studs, wood structural panel (WSP) sheathing as wall bracing and added backing for foam sheathing, a layer of rigid foam sheathing insulation up to 1.5 inches thick over the WSP, and a cladding system installed over the foam sheathing in low-rise residential buildings up to three stories high. Walls with 2x6 framing are addressed in Part 1 of the Guide.

  19. Construction Guide to Next-Generation High-Performance Walls in Climate Zones 3-5 - Part 2: 2x4 Walls

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kochkin, V.; Wiehagen, J.

    Part 2 of this Construction Guide to High-Performance Walls in Climate Zones 3-5 provides straightforward and cost-effective strategies to construct durable, energy-efficient walls. It addresses walls constructed with 2x4 wood frame studs, wood structural panel (WSP) sheathing as wall bracing and added backing for foam sheathing, a layer of rigid foam sheathing insulation up to 1.5 inches thick over the WSP, and a cladding system installed over the foam sheathing in low-rise residential buildings up to three stories high. Walls with 2x6 framing are addressed in Part 1 of the Guide.

  20. Electroosmotic flow in microchannels with arbitrary geometry and arbitrary distribution of wall charge.

    PubMed

    Xuan, Xiangchun; Li, Dongqing

    2005-09-01

    General solutions are developed for direct current (DC) and alternating current (AC) electroosmotic flows in microfluidic channels with arbitrary cross-sectional geometry and arbitrary distribution of wall charge (zeta potential). The applied AC electric field can also be of arbitrary waveform. By proposing a nondimensional time scale varpi defined as the ratio of the diffusion time of momentum across the electric double-layer thickness to the period of the applied electric field, we demonstrate analytically that the Helmholtz-Smoluchowski electroosmotic velocity is an appropriate slip condition for AC electroosmotic flows in typical microfluidic applications. With this slip condition approach, electroosmotic flows in rectangular and asymmetric trapezoidal microchannels with nonuniform wall charge, as examples, are investigated. The unknown constants in the proposed general solutions are numerically determined with a least-squares method through matching the boundary conditions. We find that the wall charge affects significantly the electroosmotic flow while the channel geometry does not. Moreover, the flow feature is characterized by another nondimensional time scale Omega defined as the ratio of the diffusion time of momentum across the channel hydraulic radius to the period of the applied electric field. The onset of phase shift between AC electroosmotic velocity and applied electric field is also examined analytically.

  1. CFD-DEM study of effect of bed thickness for bubbling fluidized beds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tingwen, Li; Gopalakrishnan, Pradeep; Garg, Rahul

    2011-10-01

    The effect of bed thickness in rectangular fluidized beds is investigated through the CFD–DEM simulations of small-scale systems. Numerical results are compared for bubbling fluidized beds of various bed thicknesses with respect to particle packing, bed expansion, bubble behavior, solids velocities, and particle kinetic energy. Good two-dimensional (2D) flow behavior is observed in the bed having a thickness of up to 20 particle diameters. However, a strong three-dimensional (3D) flow behavior is observed in beds with a thickness of 40 particle diameters, indicating the transition from 2D flow to 3D flow within the range of 20–40 particle diameters. Comparison ofmore » velocity profiles near the walls and at the center of the bed shows significant impact of the front and back walls on the flow hydrodynamics of pseudo-2D fluidized beds. Hence, for quantitative comparison with experiments in pseudo-2D columns, the effect of walls has to be accounted for in numerical simulations.« less

  2. Influence of strong perturbations on wall-bounded flows

    NASA Astrophysics Data System (ADS)

    Buxton, O. R. H.; Ewenz Rocher, M.; Rodríguez-López, E.

    2018-01-01

    Single-point hot-wire measurements are made downstream of a series of spanwise repeating obstacles that are used to generate an artificially thick turbulent boundary layer. The measurements are made in the near field, in which the turbulent boundary layer is beginning to develop from the wall-bounded wakes of the obstacles. The recent paper of Rodríguez-López et al. [E. Rodríguez-López et al., Phys. Rev. Fluids 1, 074401 (2016), 10.1103/PhysRevFluids.1.074401] broadly categorized the mechanisms by which canonical turbulent boundary layers eventually develop from wall-bounded wakes into two distinct mechanisms, the wall-driven and wake-driven mechanisms. In the present work we attempt to identify the geometric parameters of tripping arrays that trigger these two mechanisms by examining the spectra of the streamwise velocity fluctuations and the intermittent outer region of the flow. Using a definition reliant upon the magnitude of the velocity fluctuations, an intermittency function is devised that can discriminate between turbulent and nonturbulent flow. These results are presented along with the spectra in order to try to ascertain which aspects of a trip's geometry are more likely to favor the wall-driven or wake-driven mechanism. The geometrical aspects of the trips tested are the aspect ratio, the total blockage, and the blockage at the wall. The results indicate that the presence, or not, of perforations is the most significant factor in affecting the flow downstream. The bleed of fluid through the perforations reenergizes the mean recirculation and leads to a narrower intermittent region with a more regular turbulent-nonturbulent interface. The near-wall turbulent motions are found to recover quickly downstream of all of the trips with a wall blockage of 50%, but a clear influence of the outer fluctuations, generated by the tip vortices of the trips, is observed in the near-wall region for the high total blockage trips. The trip with 100% wall blockage is

  3. On the use of thick-airfoil theory to design airfoil families in which thickness and lift are varied independently

    NASA Technical Reports Server (NTRS)

    Barger, R. L.

    1974-01-01

    A method has been developed for designing families of airfoils in which the members of a family have the same basic type of pressure distribution but vary in thickness ratio or lift, or both. Thickness ratio and lift may be prescribed independently. The method which is based on the Theodorsen thick-airfoil theory permits moderate variations from the basic shape on which the family is based.

  4. Wall interference in a two-dimensional-flow wind tunnel, with consideration of the effect of compressibility

    NASA Technical Reports Server (NTRS)

    Allen, H Julian; Vincenti, Walter G

    1944-01-01

    Theoretical tunnel-wall corrections are derived for an airfoil of finite thickness and camber in a two-dimensional-flow wind tunnel. The theory takes account of the effects of the wake of the airfoil and of the compressibility of the fluid, and is based upon the assumption that the chord of the airfoil is small in comparison with the height of the tunnel. Consideration is given to the phenomenon of choking at high speeds and its relation to the tunnel-wall corrections. The theoretical results are compared with the small amount of low-speed experimental data available and the agreement is seen to be satisfactory, even for relatively large values of the chord-height ratio.

  5. Ultrasound determination of chest wall thickness: implications for needle thoracostomy.

    PubMed

    McLean, A Robb; Richards, Michael E; Crandall, Cameron S; Marinaro, Jonathan L

    2011-11-01

    Computed tomography measurements of chest wall thickness (CWT) suggest that standard-length angiocatheters (4.5 cm) may fail to decompress tension pneumothoraces. We used an alternative modality, ultrasound, to measure CWT. We correlated CWT with body mass index (BMI) and used national data to estimate the percentage of patients with CWT greater than 4.5 cm. This was an observational, cross-sectional study of a convenience sample. We recorded standing height, weight, and sex. We measured CWT with ultrasound at the second intercostal space, midclavicular line and at the fourth intercostal space, midaxillary line on supine subjects. We correlated BMI (weight [in kilograms]/height(2) [in square meters]) with CWT using linear regression. 95% Confidence intervals (CIs) assessed statistical significance. National Health and Nutrition Examination Survey results for 2007-2008 were combined to estimate national BMI adult measurements. Of 51 subjects, 33 (65%) were male and 18 (35%) were female. Mean anterior CWT (male, 2.1 cm; CI, 1.9-2.3; female, 2.3 cm; CI, 1.7-2.7), lateral CWT (male, 2.4 cm; CI, 2.1-2.6; female, 2.5 cm; CI 2.0-2.9), and BMI (male, 27.7; CI, 26.1-29.3; female, 30.0; CI, 25.8-34.2) did not differ by sex. Lateral CWT was greater than anterior CWT (0.2 cm; CI, 0.1-0.4; P < .01). Only one subject with a BMI of 48.2 had a CWT that exceeded 4.5 cm. Using national BMI estimates, less than 1% of the US population would be expected to have CWT greater than 4.5 cm. Ultrasound measurements suggest that most patients will have CWT less than 4.5 cm and that CWT may not be the source of the high failure rate of needle decompression in tension pneumothorax. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Automatic lumen and outer wall segmentation of the carotid artery using deformable three-dimensional models in MR angiography and vessel wall images.

    PubMed

    van 't Klooster, Ronald; de Koning, Patrick J H; Dehnavi, Reza Alizadeh; Tamsma, Jouke T; de Roos, Albert; Reiber, Johan H C; van der Geest, Rob J

    2012-01-01

    To develop and validate an automated segmentation technique for the detection of the lumen and outer wall boundaries in MR vessel wall studies of the common carotid artery. A new segmentation method was developed using a three-dimensional (3D) deformable vessel model requiring only one single user interaction by combining 3D MR angiography (MRA) and 2D vessel wall images. This vessel model is a 3D cylindrical Non-Uniform Rational B-Spline (NURBS) surface which can be deformed to fit the underlying image data. Image data of 45 subjects was used to validate the method by comparing manual and automatic segmentations. Vessel wall thickness and volume measurements obtained by both methods were compared. Substantial agreement was observed between manual and automatic segmentation; over 85% of the vessel wall contours were segmented successfully. The interclass correlation was 0.690 for the vessel wall thickness and 0.793 for the vessel wall volume. Compared with manual image analysis, the automated method demonstrated improved interobserver agreement and inter-scan reproducibility. Additionally, the proposed automated image analysis approach was substantially faster. This new automated method can reduce analysis time and enhance reproducibility of the quantification of vessel wall dimensions in clinical studies. Copyright © 2011 Wiley Periodicals, Inc.

  7. Bulk purification and deposition methods for selective enrichment in high aspect ratio single-walled carbon nanotubes.

    PubMed

    Bhatt, Nidhi P; Vichchulada, Pornnipa; Lay, Marcus D

    2012-06-06

    Aqueous batch processing methods for the concurrent purification of single-walled carbon nanotube (SWNT) soot and enrichment in high aspect ratio nanotubes are essential to their use in a wide variety of electronic, structural, and mechanical applications. This manuscript presents a new route to the bulk purification and enrichment of unbundled SWNTs having average lengths in excess of 2 μm. Iterative centrifugation cycles at low centripetal force not only removed amorphous C and catalyst nanoparticles but also allowed the enhanced buoyancy of surfactant encapsulated, unbundled, high aspect ratio SWNTs to be used to isolate them in the supernatant. UV-vis-NIR and Raman spectroscopy were used to verify the removal of residual impurities from as-produced (AP-grade) arc discharge soot and the simultaneous enrichment in unbundled, undamaged, high aspect ratio SWNTs. The laminar flow deposition process (LFD) used to form two-dimensional networks of SWNTs prevented bundle formation during network growth. Additionally, it further enhanced the quality of deposits by taking advantage of the inverse relationship between the translational diffusion coefficient and length for suspended nanoparticles. This resulted in preferential deposition of pristine, unbundled, high aspect ratio SWNTs over residual impurities, as observed by Raman spectroscopy and atomic force microscopy (AFM).

  8. Effect of the body wall on lithotripter shock waves.

    PubMed

    Li, Guangyan; McAteer, James A; Williams, James C; Berwick, Zachary C

    2014-04-01

    Determine the influence of passage through the body wall on the properties of lithotripter shock waves (SWs) and the characteristics of the acoustic field of an electromagnetic lithotripter. Full-thickness ex vivo segments of pig abdominal wall were secured against the acoustic window of a test tank coupled to the lithotripter. A fiber-optic probe hydrophone was used to measure SW pressures, determine shock rise time, and map the acoustic field in the focal plane. Peak positive pressure on axis was attenuated roughly proportional to tissue thickness-approximately 6% per cm. Irregularities in the tissue path affected the symmetry of SW focusing, shifting the maximum peak positive pressure laterally by as much as ∼2 mm. Within the time resolution of the hydrophone (7-15 ns), shock rise time was unchanged, measuring ∼17-21 ns with and without tissue present. Mapping of the field showed no effect of the body wall on focal width, regardless of thickness of the body wall. Passage through the body wall has minimal effect on the characteristics of lithotripter SWs. Other than reducing pulse amplitude and having the potential to affect the symmetry of the focused wave, the body wall has little influence on the acoustic field. These findings help to validate laboratory assessment of lithotripter acoustic field and suggest that the properties of SWs in the body are much the same as have been measured in vitro.

  9. Inflated Sporopollenin Exine Capsules Obtained from Thin-Walled Pollen

    NASA Astrophysics Data System (ADS)

    Park, Jae Hyeon; Seo, Jeongeun; Jackman, Joshua A.; Cho, Nam-Joon

    2016-06-01

    Sporopollenin is a physically robust and chemically resilient biopolymer that comprises the outermost layer of pollen walls and is the first line of defense against harsh environmental conditions. The unique physicochemical properties of sporopollenin increasingly motivate the extraction of sporopollenin exine capsules (SECs) from pollen walls as a renewable source of organic microcapsules for encapsulation applications. Despite the wide range of different pollen species with varying sizes and wall thicknesses, faithful extraction of pollen-mimetic SECs has been limited to thick-walled pollen capsules with rigid mechanical properties. There is an unmet need to develop methods for producing SECs from thin-walled pollen capsules which constitute a large fraction of all pollen species and have attractive materials properties such as greater aerosol dispersion. Herein, we report the first successful extraction of inflated SEC microcapsules from a thin-walled pollen species (Zea mays), thereby overcoming traditional challenges with mechanical stability and loss of microstructure. Morphological and compositional characterization of the SECs obtained by the newly developed extraction protocol confirms successful protein removal along with preservation of nanoscale architectural features. Looking forward, there is excellent potential to apply similar strategies across a wide range of unexplored thin-walled pollen species.

  10. Space- and time-resolved resistive measurements of liquid metal wall thickness.

    PubMed

    Mirhoseini, S M H; Volpe, F A

    2016-11-01

    In a fusion reactor internally coated with liquid metal, it will be important to diagnose the thickness of the liquid at various locations in the vessel, as a function of time, and possibly respond to counteract undesired bulging or depletion. The electrical conductance between electrodes immersed in the liquid metal can be used as a simple proxy for the local thickness. Here a matrix of electrodes is shown to provide spatially and temporally resolved measurements of liquid metal thickness in the absence of plasma. First a theory is developed for m × n electrodes, and then it is experimentally demonstrated for 3 × 1 electrodes, as the liquid stands still or is agitated by means of a shaker. The experiments were carried out with Galinstan, but are easily extended to lithium or other liquid metals.

  11. Sedimentary and crustal thicknesses and Poisson's ratios for the NE Tibetan Plateau and its adjacent regions based on dense seismic arrays

    NASA Astrophysics Data System (ADS)

    Wang, Weilai; Wu, Jianping; Fang, Lihua; Lai, Guijuan; Cai, Yan

    2017-03-01

    The sedimentary and crustal thicknesses and Poisson's ratios of the NE Tibetan Plateau and its adjacent regions are estimated by the h- κ stacking and CCP image of receiver functions from the data of 1,317 stations. The horizontal resolution of the obtained results is as high as 0.5° × 0.5°, which can be used for further high resolution model construction in the region. The crustal thicknesses from Airy's equilibrium are smaller than our results in the Sichuan Basin, Qilian tectonic belt, northern Alxa block and Qaidam Basin, which is consistent with the high densities in the mantle lithosphere and may indicate that the high-density lithosphere drags crust down overall. High Poisson's ratios and low velocity zones are found in the mid- and lower crust beneath eastern Qilian tectonic belt and the boundary areas of the Ordos block, indicating that partial melting may exist in these regions. Low Poisson's ratios and low-velocity anomalies are observed in the crust in the NE Tibetan Plateau, implying that the mafic lower crust is thinning or missing and that the mid- and lower crust does not exhibit melting or partial melting in the NE Tibetan Plateau, and weak flow layers are not likely to exist in this region.

  12. The relationship between accommodative amplitude and the ratio of central lens thickness to its equatorial diameter in vertebrate eyes

    PubMed Central

    Schachar, Ronald A; Pierscionek, Barbara K; Abolmaali, Ali; Le, Tri

    2007-01-01

    Aim To determine the relationship between accommodative amplitude and central lens thickness/equatorial lens diameter (CLT/ELD) ratio in vertebrates. Methods Midsagittal sections of lenses from fixed, post mortem eyes from 125 different vertebrate species were photographed. Their CLT/ELD ratios were correlated with independently published measurements of their accommodative amplitudes. Using the non‐linear finite element method (FEM), the efficiency of zonular traction (the absolute change in central radius of curvature per unit force [|ΔCR|/F]) for model lenses with CLT/ELD ratios from 0.45 to 0.9 was determined. Results Vertebrates with CLT/ELD ratios ⩽0.6 have high accommodative amplitudes. Zonular traction was found to be most efficient for those model lenses having CLT/ELD ratios ⩽0.6. Conclusions Vertebrates with lenses that have CLT/ELD ratios ⩽0.6 – i.e. “long oval” shapes – have the greatest accommodative amplitudes; e.g. primates, diving birds and diurnal birds of prey. Vertebrates that have oval or spherical shaped lenses, like owls and most mammals, have low accommodative amplitudes. Zonular traction was found to be most efficient when applied to model lenses with CLT/ELD ratios ⩽0.6. The implications of these findings on the mechanism of accommodation are discussed. PMID:17050574

  13. Effect of nitrogen levels and nitrogen ratios on lodging resistance and yield potential of winter wheat (Triticum aestivum L.)

    PubMed Central

    Wang, Hui; Yi, Yuan; Ding, Jinfeng; Zhu, Min; Li, Chunyan; Guo, Wenshan; Feng, Chaonian; Zhu, Xinkai

    2017-01-01

    Lodging is one of the constraints that limit wheat yields and quality due to the unexpected bending or breaking stems on wheat (Triticum aestivum L.) production worldwide. In addition to choosing lodging resistance varieties, husbandry practices also have a significant effect on lodging. Nitrogen management is one of the most common and efficient methods. A field experiment with Yangmai 20 as research material (a widely-used variety) was conducted to study the effects of different nitrogen levels and ratios on culm morphological, anatomical characters and chemical components and to explore the nitrogen application techniques for lodging tolerance and high yield. Results showed that some index of basal internodes, such as stem wall thickness, filling degree, lignin content, cellulose content, water-soluble carbohydrate (WSC) and WSC/N ratio, were positively and significantly correlated with culm lodging-resistant index (CLRI). As the increase of nitrogen level and basal nitrogen ratio, the basal internodes became slender and fragile with the thick stem wall, while filling degree, chemical components and the strength of the stem decreased gradually, which significantly increased the lodging risk. The response of grain yield to nitrogen doses was quadratic and grain yield reached the highest at the nitrogen ratio of 50%:10%:20%:20% (the ratio of nitrogen amount applied before sowing, at tillering stage, jointing stage and booting stage respectively, abbreviated as 5:1:2:2). These results suggested that for Yangmai 20, the planting density of 180×104ha-1, nitrogen level of 225 kg ha-1, and the ratio of 5: 1: 2: 2 effectively increased lodging resistance and grain yield. This combination of planting density and nitrogen level and ratio could effectively relieve the contradiction between high-yielding and anti-lodging. PMID:29117250

  14. Effect of nitrogen levels and nitrogen ratios on lodging resistance and yield potential of winter wheat (Triticum aestivum L.).

    PubMed

    Zhang, Mingwei; Wang, Hui; Yi, Yuan; Ding, Jinfeng; Zhu, Min; Li, Chunyan; Guo, Wenshan; Feng, Chaonian; Zhu, Xinkai

    2017-01-01

    Lodging is one of the constraints that limit wheat yields and quality due to the unexpected bending or breaking stems on wheat (Triticum aestivum L.) production worldwide. In addition to choosing lodging resistance varieties, husbandry practices also have a significant effect on lodging. Nitrogen management is one of the most common and efficient methods. A field experiment with Yangmai 20 as research material (a widely-used variety) was conducted to study the effects of different nitrogen levels and ratios on culm morphological, anatomical characters and chemical components and to explore the nitrogen application techniques for lodging tolerance and high yield. Results showed that some index of basal internodes, such as stem wall thickness, filling degree, lignin content, cellulose content, water-soluble carbohydrate (WSC) and WSC/N ratio, were positively and significantly correlated with culm lodging-resistant index (CLRI). As the increase of nitrogen level and basal nitrogen ratio, the basal internodes became slender and fragile with the thick stem wall, while filling degree, chemical components and the strength of the stem decreased gradually, which significantly increased the lodging risk. The response of grain yield to nitrogen doses was quadratic and grain yield reached the highest at the nitrogen ratio of 50%:10%:20%:20% (the ratio of nitrogen amount applied before sowing, at tillering stage, jointing stage and booting stage respectively, abbreviated as 5:1:2:2). These results suggested that for Yangmai 20, the planting density of 180×104ha-1, nitrogen level of 225 kg ha-1, and the ratio of 5: 1: 2: 2 effectively increased lodging resistance and grain yield. This combination of planting density and nitrogen level and ratio could effectively relieve the contradiction between high-yielding and anti-lodging.

  15. Space- and time-resolved resistive measurements of liquid metal wall thickness

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mirhoseini, S. M. H.; Volpe, F. A., E-mail: fvolpe@columbia.edu

    In a fusion reactor internally coated with liquid metal, it will be important to diagnose the thickness of the liquid at various locations in the vessel, as a function of time, and possibly respond to counteract undesired bulging or depletion. The electrical conductance between electrodes immersed in the liquid metal can be used as a simple proxy for the local thickness. Here a matrix of electrodes is shown to provide spatially and temporally resolved measurements of liquid metal thickness in the absence of plasma. First a theory is developed for m × n electrodes, and then it is experimentally demonstratedmore » for 3 × 1 electrodes, as the liquid stands still or is agitated by means of a shaker. The experiments were carried out with Galinstan, but are easily extended to lithium or other liquid metals.« less

  16. Association of aortic wall thickness on contrast-enhanced chest CT with major cerebro-cardiac events.

    PubMed

    Tresoldi, Silvia; Di Leo, Giovanni; Zoffoli, Elena; Munari, Alice; Primolevo, Alessandra; Cornalba, Gianpaolo; Sardanelli, Francesco

    2014-11-01

    There is a significant association between aortic atherosclerosis and previous major cardiovascular events. Particularly, thoracic aortic atherosclerosis is closely related to the degree of coronary and carotid artery disease. Thus, there is a rationale for screening the thoracic aorta in patients who undergo a chest computed tomography (CT) for any clinical question, in order to detect patients at increased risk of cerebro-cardiovascular (CCV) events. To estimate the association between either thoracic aortic wall thickness (AWT) or aortic total calcium score (ATCS) and CCV events. One hundred and forty-eight non-cardiac patients (78 men; 67 ± 12 years) underwent chest contrast-enhanced multidetector CT (MDCT). The AWT was measured at the level of the left atrium (AWTref) and at the maximum AWT (AWTmax). Correlation with clinical CCV patients' history was estimated. The value of AWTmax and of a semi-quantitative ATCS as a marker for CCV events was assessed using receiver-operating characteristic curve (ROC) analysis and multivariate regression analysis. Out of 148 patients, 59% reported sedentary lifestyle, 44% hypertension, 32% smoking, 23% hypercholesterolemia, 13% family history of cardiac disease, 12% diabetes, and 10% BMI ≥ 30 kg/m(2); 9% reported myocardial infarction, 8% aortic aneurism, 8% myocardial revascularization, and 2% ischemic stroke. Twenty-six percent of patients had a medium-to-high ATCS. Both AWTmax and AWTref correlated with hypertension and age (P < 0.002). At the ROC analysis, a 4.8 mm threshold was associated to a 90% specificity and an odds ratio of 6.3 (AUC = 0.735). Assuming as threshold the AWTmax median value (4.3 mm) of patients who suffered from at least one CCV event in their history, a negative predictive value of 90%, a RR of 3.6 and an OR of 6.3 were found. At the multivariate regression analysis, AWTmax was the only independent variable associated to the frequency of CCV events. Patients with increased thoracic

  17. Measure Guideline. Incorporating Thick Layers of Exterior Rigid Insulation on Walls

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lstiburek, Joseph; Baker, Peter

    This measure guideline, written by the U.S. Department of Energy’s Building America team Building Science Corporation, provides information about the design and construction of wall assemblies that use layers of rigid exterior insulation thicker than 1-½ in. and that require a secondary cladding attachment location exterior to the insulation. The guideline is separated into several distinct sections that cover: (1) fundamental building science principles relating to the use of exterior insulation on wall assemblies; (2) design principles for tailoring this use to the specific project goals and requirements; and (3) construction detailing to increase understanding about implementing the various designmore » elements.« less

  18. Exposure to chronic alcohol accelerates development of wall stress and eccentric remodeling in rats with volume overload.

    PubMed

    Mouton, Alan J; Ninh, Van K; El Hajj, Elia C; El Hajj, Milad C; Gilpin, Nicholas W; Gardner, Jason D

    2016-08-01

    Chronic alcohol abuse is one of the leading causes of dilated cardiomyopathy (DCM) in the United States. Volume overload (VO) also produces DCM characterized by left ventricular (LV) dilatation and reduced systolic and diastolic function, eventually progressing to congestive heart failure. For this study, we hypothesized that chronic alcohol exposure would exacerbate cardiac dysfunction and remodeling due to VO. Aortocaval fistula surgery was used to induce VO, and compensatory cardiac remodeling was allowed to progress for either 3days (acute) or 8weeks (chronic). Alcohol was administered via chronic intermittent ethanol vapor (EtOH) for 2weeks before the acute study and for the duration of the 8week chronic study. Temporal alterations in LV function were assessed by echocardiography. At the 8week end point, pressure-volume loop analysis was performed by LV catheterization and cardiac tissue collected. EtOH did not exacerbate LV dilatation (end-systolic and diastolic diameter) or systolic dysfunction (fractional shortening, ejection fraction) due to VO. The combined stress of EtOH and VO decreased the eccentric index (posterior wall thickness to end-diastolic diameter ratio), increased end-diastolic pressure (EDP), and elevated diastolic wall stress. VO also led to increases in posterior wall thickness, which was not observed in the VO+EtOH group, and wall thickness significantly correlated with LV BNP expression. VO alone led to increases in interstitial collagen staining (picrosirius red), which while not statistically significant, tended to be decreased by EtOH. VO increased LV collagen I protein expression, whereas in rats with VO+EtOH, LV collagen I was not elevated relative to Sham. The combination of VO and EtOH also led to increases in LV collagen III expression relative to Sham. Rats with VO+EtOH had significantly lower collagen I/III ratio than rats with VO alone. During the acute remodeling phase of VO (3days), VO significantly increased collagen III

  19. Inflated Sporopollenin Exine Capsules Obtained from Thin-Walled Pollen

    PubMed Central

    Park, Jae Hyeon; Seo, Jeongeun; Jackman, Joshua A.; Cho, Nam-Joon

    2016-01-01

    Sporopollenin is a physically robust and chemically resilient biopolymer that comprises the outermost layer of pollen walls and is the first line of defense against harsh environmental conditions. The unique physicochemical properties of sporopollenin increasingly motivate the extraction of sporopollenin exine capsules (SECs) from pollen walls as a renewable source of organic microcapsules for encapsulation applications. Despite the wide range of different pollen species with varying sizes and wall thicknesses, faithful extraction of pollen-mimetic SECs has been limited to thick-walled pollen capsules with rigid mechanical properties. There is an unmet need to develop methods for producing SECs from thin-walled pollen capsules which constitute a large fraction of all pollen species and have attractive materials properties such as greater aerosol dispersion. Herein, we report the first successful extraction of inflated SEC microcapsules from a thin-walled pollen species (Zea mays), thereby overcoming traditional challenges with mechanical stability and loss of microstructure. Morphological and compositional characterization of the SECs obtained by the newly developed extraction protocol confirms successful protein removal along with preservation of nanoscale architectural features. Looking forward, there is excellent potential to apply similar strategies across a wide range of unexplored thin-walled pollen species. PMID:27302853

  20. In-place oil shale resources of the Mahogany zone sorted by grade, overburden thickness and stripping ratio, Green River Formation, Piceance Basin, Colorado and Uinta Basin, Utah

    USGS Publications Warehouse

    Birdwell, Justin E.; Mercier, Tracey J.; Johnson, Ronald C.; Brownfield, Michael E.

    2015-01-01

    A range of geological parameters relevant to mining oil shale have been examined for the Mahogany zone of the Green River Formation in the Piceance Basin, Colorado, and Uinta Basin, Utah, using information available in the U.S. Geological Survey Oil Shale Assessment database. Basinwide discrete and cumulative distributions of resource in-place as a function of (1) oil shale grade, (2) Mahogany zone thickness, (3) overburden thickness, and (4) stripping ratio (overburden divided by zone thickness) were determined for both basins on a per-acre basis, and a resource map showing the areal distribution of these properties was generated. Estimates of how much of the Mahogany zone resource meets various combinations of these parameters were also determined. Of the 191.7 billion barrels of Mahogany zone oil in-place in the Piceance Basin, 32.3 percent (61.8 billion barrels) is associated with oil shale yielding at least 25 gallons of oil per ton (GPT) of rock processed, is covered by overburden 1,000 feet thick or less, and has a stripping ratio of less than 10. In the Uinta Basin, 14.0 percent (29.9 billion barrels) of the 214.5 billion barrels of Mahogany zone oil in-place meets the same overburden and stripping ratio criteria but only for the lower grade cutoff of 15 GPT.

  1. Right ventricular relative wall thickness as a predictor of outcomes and of right ventricular reverse remodeling for patients with pulmonary hypertension.

    PubMed

    Sano, Hiroyuki; Tanaka, Hidekazu; Motoji, Yoshiki; Fukuda, Yuko; Mochizuki, Yasuhide; Hatani, Yutaka; Matsuzoe, Hiroki; Hatazawa, Keiko; Shimoura, Hiroyuki; Ooka, Junichi; Ryo-Koriyama, Keiko; Nakayama, Kazuhiko; Matsumoto, Kensuke; Emoto, Noriaki; Hirata, Ken-Ichi

    2017-03-01

    Mid-term right ventricular (RV) reverse remodeling after treatment in patients with pulmonary hypertension (PH) is associated with long-term outcome as well as baseline RV remodeling. However, baseline factors influencing mid-term RV reverse remodeling after treatment and its prognostic capability remain unclear. We studied 54 PH patients. Mid-term RV remodeling was assessed in terms of the RV area, which was traced planimetrically at the end-systole (RVESA). RV reverse remodeling was defined as a relative decrease in the RVESA of at least 15% at 10.2 ± 9.4 months after treatment. Long-term follow-up was 5 years. Adverse events occurred in ten patients (19%) and mid-term RV reverse remodeling after treatment was observed in 37 (69%). Patients with mid-term RV reverse remodeling had more favorable long-term outcomes than those without (log-rank: p = 0.01). Multivariate logistic regression analysis showed that RV relative wall thickness (RV-RWT), as calculated as RV free-wall thickness/RV basal linear dimension at end-diastole, was an independent predictor of mid-term RV reverse remodeling (OR 1.334; 95% CI, 1.039-1.713; p = 0.03). Moreover, patients with RV-RWT ≥0.21 showed better long-term outcomes than did those without (log-rank p = 0.03), while those with RV-RWT ≥0.21 and mid-term RV reverse remodeling had the best long-term outcomes. Patients with RV-RWT <0.21 and without mid-term RV reverse remodeling, on the other hand, had worse long-term outcomes than other sub-groups. In conclusions, RV-RWT could predict mid-term RV reverse remodeling after treatment in PH patients, and was associated with long-term outcomes. Our finding may have clinical implications for better management of PH patients.

  2. Development of a Versatile Laser-Ultrasonic System and Application to the Online Measurement for Process Control of Wall Thickness and Eccentricity of Seamless Tubes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Robert V. Kolarik II

    2002-10-23

    A system for the online, non-contact measurement of wall thickness in steel seamless mechanical tubing has been developed and demonstrated at a tubing production line at the Timken Company in Canton, Ohio. The system utilizes laser-generation of ultrasound and laser-detection of time of flight with interferometry, laser-doppler velocimetry and pyrometry, all with fiber coupling. Accuracy (<1% error) and precision (1.5%) are at targeted levels. Cost and energy savings have exceeded estimates. The system has shown good reliability in measuring over 200,000 tubes in its first six months of deployment.

  3. Utilizing the ratio and the summation of two spectral lines for estimation of optical depth: Focus on thick plasmas

    NASA Astrophysics Data System (ADS)

    Rezaei, Fatemeh; Tavassoli, Seyed Hassan

    2016-11-01

    In this paper, a study is performed on the spectral lines of plasma radiations created from focusing of the Nd:YAG laser on Al standard alloys at atmospheric air pressure. A new theoretical method is presented to investigate the evolution of the optical depth of the plasma based on the radiative transfer equation, in LTE condition. This work relies on the Boltzmann distribution, lines broadening equations, and as well as the self-absorption relation. Then, an experimental set-up is devised to extract some of plasma parameters such as temperature from modified line ratio analysis, electron density from Stark broadening mechanism, line intensities of two spectral lines in the same order of ionization from similar species, and the plasma length from the shadowgraphy section. In this method, the summation and the ratio of two spectral lines are considered for evaluation of the temporal variations of the plasma parameters in a LIBS homogeneous plasma. The main advantage of this method is that it comprises the both of thin and thick laser induced plasmas without straight calculation of self-absorption coefficient. Moreover, the presented model can also be utilized for evaluation the transition of plasma from the thin condition to the thick one. The results illustrated that by measuring the line intensities of two spectral lines at different evolution times, the plasma cooling and the growth of the optical depth can be followed.

  4. Wall stress reduction in abdominal aortic aneurysms as a result of polymeric endoaortic paving.

    PubMed

    Ashton, John H; Ayyalasomayajula, Avinash; Simon, Bruce R; Vande Geest, Jonathan P

    2011-06-01

    Polymeric endoaortic paving (PEAP) may improve endovascular repair of abdominal aortic aneurysms (AAA) since it has the potential to treat patients with complex AAA geometries while reducing the incidence of migration and endoleak. Polycaprolactone (PCL)/polyurethane (PU) blends are proposed as PEAP materials due to their range of mechanical properties, thermoformability, and resistance to biodegradation. In this study, the reduction in AAA wall stress that can be achieved using PEAP was estimated and compared to that resulting from stent-grafts. This was accomplished by mechanically modeling the anisotropic response of PCL/PU blends and implementing these results into finite element model (FEM) simulations. We found that at the maximum diameter of the AAA, the 50/50 and 10/90 PCL/PU blends reduced wall stress by 99 and 98%, respectively, while a stent-graft reduced wall stress by 99%. Our results also show that wall stress reduction increases with increasing PEAP thickness and PCL content in the blend ratio. These results indicate that PEAP can reduce AAA wall stress as effectively as a stent-graft. As such, we propose that PEAP may provide an improved treatment alternative for AAA, since many of the limitations of stent-grafts have the potential to be solved using this approach.

  5. Some considerations on instability of combined loaded thin-walled tubes with a crack

    NASA Astrophysics Data System (ADS)

    Shariati, M.; Akbarpour, A.

    2016-05-01

    Instability of a thin-walled stainless steel tube with a crack-shaped defect under combined loading is studied in this paper. Furthermore, the effects of the tube length, crack orientation, and crack length on the buckling behavior of tubes are investigated. The behavior of tubes subjected to combined is analyzed by using the finite element method (by Abaqus software). For cracked tubes with a fixed thickness, the buckling load decreases as the tube length and the ratio of the tube length to its diameter increase. Moreover, the buckling load of cracked tubes under combined loading also decreases with increasing crack length.

  6. Cooperative Assembly of Magneto-Nanovesicles with Tunable Wall Thickness and Permeability for MRI-Guided Drug Delivery.

    PubMed

    Yang, Kuikun; Liu, Yijing; Liu, Yi; Zhang, Qian; Kong, Chuncai; Yi, Chenglin; Zhou, Zijian; Wang, Zhantong; Zhang, Guofeng; Zhang, Yang; Khashab, Niveen M; Chen, Xiaoyuan; Nie, Zhihong

    2018-04-04

    This article describes the fabrication of nanosized magneto-vesicles (MVs) comprising tunable layers of densely packed superparamagnetic iron oxide nanoparticles (SPIONs) in membranes via cooperative assembly of polymer-tethered SPIONs and free poly(styrene)- b-poly(acrylic acid) (PS- b-PAA). The membrane thickness of MVs could be well controlled from 9.8 to 93.2 nm by varying the weight ratio of PS- b-PAA to SPIONs. The increase in membrane thickness was accompanied by the transition from monolayer MVs, to double-layered MVs and to multilayered MVs (MuMVs). This can be attributed to the variation in the hydrophobic/hydrophilic balance of polymer-grafted SPIONs upon the insertion and binding of PS- b-PAA onto the surface of nanoparticles. Therapeutic agents can be efficiently encapsulated in the hollow cavity of MVs and the release of payload can be tuned by varying the membrane thickness of nanovesicles. Due to the high packing density of SPIONs, the MuMVs showed the highest magnetization and transverse relaxivity rate ( r 2 ) in magnetic resonance imaging (MRI) among these MVs and individual SPIONs. Upon intravenous injection, doxorubicin-loaded MuMVs conjugated with RGD peptides could be effectively enriched at tumor sites due to synergetic effect of magnetic and active targeting. As a result, they exhibited drastically enhanced signal in MRI, improved tumor delivery efficiency of drugs as well as enhanced antitumor efficacy, compared with groups with only magnetic or active targeting strategy. The unique nanoplatform may find applications in effective disease control by delivering imaging and therapy to organs/tissues that are not readily accessible by conventional delivery vehicles.

  7. Controlled Patterning and Growth of Single Wall and Multi-wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor)

    2005-01-01

    Method and system for producing a selected pattern or array of at least one of a single wall nanotube and/or a multi-wall nanotube containing primarily carbon. A substrate is coated with a first layer (optional) of a first selected metal (e.g., Al and/or Ir) and with a second layer of a catalyst (e.g., Fe, Co, Ni and/or Mo), having selected first and second layer thicknesses provided by ion sputtering, arc discharge, laser ablation, evaporation or CVD. The first layer and/or the second layer may be formed in a desired non-uniform pattern, using a mask with suitable aperture(s), to promote growth of carbon nanotubes in a corresponding pattern. A selected heated feed gas (primarily CH4 or C2Hn with n=2 and/or 4) is passed over the coated substrate and forms primarily single wall nanotubes or multiple wall nanotubes, depending upon the selected feed gas and its temperature. Nanofibers, as well as single wall and multi-wall nanotubes, are produced using plasma-aided growth from the second (catalyst) layer. An overcoating of a selected metal or alloy can be deposited, over the second layer, to provide a coating for the carbon nanotubes grown in this manner.

  8. Double wall vacuum tubing and method of manufacture

    DOEpatents

    Stahl, Charles R.; Gibson, Michael A.; Knudsen, Christian W.

    1989-01-01

    An evacuated double wall tubing is shown together with a method for the manufacture of such tubing which includes providing a first pipe of predetermined larger diameter and a second pipe having an O.D. substantially smaller than the I.D. of the first pipe. An evacuation opening is then in the first pipe. The second pipe is inserted inside the first pipe with an annular space therebetween. The pipes are welded together at one end. A stretching tool is secured to the other end of the second pipe after welding. The second pipe is then prestressed mechanically with the stretching tool an amount sufficient to prevent substantial buckling of the second pipe under normal operating conditions of the double wall pipe. The other ends of the first pipe and the prestressed second pipe are welded together, preferably by explosion welding, without the introduction of mechanical spacers between the pipes. The annulus between the pipes is evacuated through the evacuation opening, and the evacuation opening is finally sealed. The first pipe is preferably of steel and the second pipe is preferably of titanium. The pipes may be of a size and wall thickness sufficient for the double wall pipe to be structurally load bearing or may be of a size and wall thickness insufficient for the double wall pipe to be structurally load bearing, and the double wall pipe positioned with a sliding fit inside a third pipe of a load-bearing size.

  9. Cell Wall Remodeling Enzymes Modulate Fungal Cell Wall Elasticity and Osmotic Stress Resistance

    PubMed Central

    Ene, Iuliana V.; Walker, Louise A.; Schiavone, Marion; Lee, Keunsook K.; Martin-Yken, Hélène; Dague, Etienne; Gow, Neil A. R.; Munro, Carol A.

    2015-01-01

    ABSTRACT The fungal cell wall confers cell morphology and protection against environmental insults. For fungal pathogens, the cell wall is a key immunological modulator and an ideal therapeutic target. Yeast cell walls possess an inner matrix of interlinked β-glucan and chitin that is thought to provide tensile strength and rigidity. Yeast cells remodel their walls over time in response to environmental change, a process controlled by evolutionarily conserved stress (Hog1) and cell integrity (Mkc1, Cek1) signaling pathways. These mitogen-activated protein kinase (MAPK) pathways modulate cell wall gene expression, leading to the construction of a new, modified cell wall. We show that the cell wall is not rigid but elastic, displaying rapid structural realignments that impact survival following osmotic shock. Lactate-grown Candida albicans cells are more resistant to hyperosmotic shock than glucose-grown cells. We show that this elevated resistance is not dependent on Hog1 or Mkc1 signaling and that most cell death occurs within 10 min of osmotic shock. Sudden decreases in cell volume drive rapid increases in cell wall thickness. The elevated stress resistance of lactate-grown cells correlates with reduced cell wall elasticity, reflected in slower changes in cell volume following hyperosmotic shock. The cell wall elasticity of lactate-grown cells is increased by a triple mutation that inactivates the Crh family of cell wall cross-linking enzymes, leading to increased sensitivity to hyperosmotic shock. Overexpressing Crh family members in glucose-grown cells reduces cell wall elasticity, providing partial protection against hyperosmotic shock. These changes correlate with structural realignment of the cell wall and with the ability of cells to withstand osmotic shock. PMID:26220968

  10. Process for forming a long gas turbine engine blade having a main wall with a thin portion near a tip

    DOEpatents

    Campbell, Christian X; Thomaidis, Dimitrios

    2014-05-13

    A process is provided for forming an airfoil for a gas turbine engine involving: forming a casting of a gas turbine engine airfoil having a main wall and an interior cavity, the main wall having a wall thickness extending from an external surface of the outer wall to the interior cavity, an outer section of the main wall extending from a location between a base and a tip of the airfoil casting to the tip having a wall thickness greater than a final thickness. The process may further involve effecting movement, using a computer system, of a material removal apparatus and the casting relative to one another such that a layer of material is removed from the casting at one or more radial portions along the main wall of the casting.

  11. Numerical and experimental investigation of strip deformation in cage roll forming process for pipes with low ratio of thickness/diameter

    NASA Astrophysics Data System (ADS)

    Kasaei, M. M.; Naeini, H. Moslemi; Tehrani, M. Salmani; Tafti, R. Azizi

    2011-01-01

    Cage roll forming is one of the advanced methods of cold roll forming process which is used widely for producing ERW pipes. In addition to decreasing the production cost and time, using cage roll forming provides smooth deformation on the strip. Few studies can be found about cage roll forming because of its complexity, and the available knowledge is experience-based more than science-based. In this paper, deformation of pipes with low ratio of thickness/diameter is investigated by 3D finite element simulation in Marc-Mentat software. Edge buckling defect in cage roll forming of low ratio of thickness/diameter pipes is very important. Due to direct influence of longitudinal strain on the edge buckling phenomenon, longitudinal strains at the edge and center line of the strip are investigated and high risk stands are introduced. The deformed strip is predicted using the simulation results and effects of each cage forming stage on the deformed strip profile are specified. In order to verify the simulation results, strip width and opening distance of the two edges in different forming stages are obtained from the simulations and compared with the experimental data which were measured from the production line. A good agreement between the experimental and simulated results is observed.

  12. High-frequency guided ultrasonic waves to monitor corrosion thickness loss

    NASA Astrophysics Data System (ADS)

    Fromme, Paul; Bernhard, Fabian; Masserey, Bernard

    2017-02-01

    Corrosion due to adverse environmental conditions can occur for a range of industrial structures, e.g., ships and offshore oil platforms. Pitting corrosion and generalized corrosion can lead to the reduction of the strength and thus degradation of the structural integrity. The nondestructive detection and monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided ultrasonic waves propagating along the structure. Using standard ultrasonic transducers with single sided access to the structure, the two fundamental Lamb wave modes were selectively generated simultaneously, penetrating through the complete thickness of the structure. The wave propagation and interference of the guided wave modes depends on the thickness of the structure. Numerical simulations were performed using a 2D Finite Difference Method (FDM) algorithm in order to visualize the guided wave propagation and energy transfer across the plate thickness. Laboratory experiments were conducted and the wall thickness reduced initially uniformly by milling of the steel structure. Further measurements were conducted using accelerated corrosion in salt water. From the measured signal change due to the wave mode interference, the wall thickness reduction was monitored and good agreement with theoretical predictions was achieved. Corrosion can lead to non-uniform thickness reduction and the influence of this on the propagation of the high frequency guided ultrasonic waves was investigated. The wave propagation in a steel specimen with varying thickness was measured experimentally and the influence on the wave propagation characteristics quantified.

  13. Optimization of laser energy deposition for single-shot high aspect-ratio microstructuring of thick BK7 glass

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Garzillo, Valerio; Grigutis, Robertas; Jukna, Vytautas

    We investigate the generation of high aspect ratio microstructures across 0.7 mm thick glass by means of single shot Bessel beam laser direct writing. We study the effect on the photoinscription of the cone angle, as well as of the energy and duration of the ultrashort laser pulse. The aim of the study is to optimize the parameters for the writing of a regular microstructure due to index modification along the whole sample thickness. By using a spectrally resolved single pulse transmission diagnostics at the output surface of the glass, we correlate the single shot material modification with observations of themore » absorption in different portions of the retrieved spectra, and with the absence or presence of spectral modulation. Numerical simulations of the evolution of the Bessel pulse intensity and of the energy deposition inside the sample help us interpret the experimental results that suggest to use picosecond pulses for an efficient and more regular energy deposition. Picosecond pulses take advantage of nonlinear plasma absorption and avoid temporal dynamics effects which can compromise the stationarity of the Bessel beam propagation.« less

  14. Reliability Criteria for Thick Bonding Wire.

    PubMed

    Dagdelen, Turker; Abdel-Rahman, Eihab; Yavuz, Mustafa

    2018-04-17

    Bonding wire is one of the main interconnection techniques. Thick bonding wire is widely used in power modules and other high power applications. This study examined the case for extending the use of traditional thin wire reliability criteria, namely wire flexure and aspect ratio, to thick wires. Eleven aluminum (Al) and aluminum coated copper (CucorAl) wire samples with diameter 300 μm were tested experimentally. The wire response was measured using a novel non-contact method. High fidelity FEM models of the wire were developed and validated. We found that wire flexure is not correlated to its stress state or fatigue life. On the other hand, aspect ratio is a consistent criterion of thick wire fatigue life. Increasing the wire aspect ratio lowers its critical stress and increases its fatigue life. Moreover, we found that CucorAl wire has superior performance and longer fatigue life than Al wire.

  15. Reliability Criteria for Thick Bonding Wire

    PubMed Central

    Yavuz, Mustafa

    2018-01-01

    Bonding wire is one of the main interconnection techniques. Thick bonding wire is widely used in power modules and other high power applications. This study examined the case for extending the use of traditional thin wire reliability criteria, namely wire flexure and aspect ratio, to thick wires. Eleven aluminum (Al) and aluminum coated copper (CucorAl) wire samples with diameter 300 μm were tested experimentally. The wire response was measured using a novel non-contact method. High fidelity FEM models of the wire were developed and validated. We found that wire flexure is not correlated to its stress state or fatigue life. On the other hand, aspect ratio is a consistent criterion of thick wire fatigue life. Increasing the wire aspect ratio lowers its critical stress and increases its fatigue life. Moreover, we found that CucorAl wire has superior performance and longer fatigue life than Al wire. PMID:29673194

  16. 3D cardiac wall thickening assessment for acute myocardial infarction

    NASA Astrophysics Data System (ADS)

    Khalid, A.; Chan, B. T.; Lim, E.; Liew, Y. M.

    2017-06-01

    Acute myocardial infarction (AMI) is the most severe form of coronary artery disease leading to localized myocardial injury and therefore irregularities in the cardiac wall contractility. Studies have found very limited differences in global indices (such as ejection fraction, myocardial mass and volume) between healthy subjects and AMI patients, and therefore suggested regional assessment. Regional index, specifically cardiac wall thickness (WT) and thickening is closely related to cardiac function and could reveal regional abnormality due to AMI. In this study, we developed a 3D wall thickening assessment method to identify regional wall contractility dysfunction due to localized myocardial injury from infarction. Wall thickness and thickening were assessed from 3D personalized cardiac models reconstructed from cine MRI images by fitting inscribed sphere between endocardial and epicardial wall. The thickening analysis was performed in 5 patients and 3 healthy subjects and the results were compared against the gold standard 2D late-gadolinium-enhanced (LGE) images for infarct localization. The notable finding of this study is the highly accurate estimation and visual representation of the infarct size and location in 3D. This study provides clinicians with an intuitive way to visually and qualitatively assess regional cardiac wall dysfunction due to infarction in AMI patients.

  17. The Relationship of Educational Attainment with Pulmonary Emphysema and Airway Wall Thickness.

    PubMed

    Gjerdevik, Miriam; Grydeland, Thomas B; Washko, George R; Coxson, Harvey O; Silverman, Edwin K; Gulsvik, Amund; Bakke, Per S

    2015-06-01

    Low educational attainment is a risk factor of chronic obstructive pulmonary disease (COPD). There is limited knowledge on the relationship between educational level and computed tomography measures of emphysema and airway wall thickness (AWT). We hypothesized that low educational attainment is associated with increased emphysema and AWT in ever-smokers with and without COPD. We included 462 and 485 ever-smokers with and without COPD in a cross-sectional study, aged 40-86 years. The sample was divided into groups reflecting educational attainment: primary, secondary, and university. We performed linear regression to examine associations between educational attainment and both emphysema and AWT separately for those with and without COPD. We adjusted for sex, age, smoking status, age of onset of smoking, pack-years, height, and body mass index. Compared with university education, in subjects with COPD, primary education was associated with a 68.1% (95% confidence interval = 14.2-147.6%; P = 0.01) relative increase in emphysema and secondary education was associated with a 50.6% (95% confidence interval = 5.7-114.6%; P = 0.02) relative increase. There was a nonsignificant trend toward an association between lower educational attainment and increased emphysema among those without COPD (P = 0.18), yet greater age appeared to modify this association (P = 0.01). We did not detect significant linear relationships between educational attainment and AWT in subjects with or without COPD. Lower educational attainment was associated with increased emphysema among adults with COPD. Among those without COPD, this association was more pronounced with increasing age. No significant linear relationship between educational attainment and AWT was found. Clinicians treating adults with emphysema should keep in mind that factors related to low education beyond that of smoking and occupational dust exposure might be of importance to the disease.

  18. A numerical study of multiple adiabatic shear bands evolution in a 304LSS thick-walled cylinder

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    The self-organization of multiple shear bands in a 304L stainless steel(304LSS) thick-walled cylinder (TWC) was numerically studied. The microstructures of material lead to the non-uniform distribution of the local yield stress, which play a key role in the formation of spontaneous shear localization. We introduced a probability factor satisfied the Gaussian distribution into the macroscopic constitutive relationship to describe the non-uniformity of local yield stress. Using the probability factor, the initiation and propagation of multiple shear bands in TWC were numerically replicated in our 2D FEM simulation. Experimental results in the literature indicated that the machined surface at the internal boundary of a 304L stainless steel cylinder provides a work-hardened layer (about 20˜30μm) which has significantly different microstructures from the base material. The work-hardened layer leads to the phenomenon that most shear bands propagate along a given direction, clockwise or counterclockwise. In our simulation, periodical single direction spiral perturbations were applied to describe the grain orientation in the work-hardened layer, and the single direction spiral pattern of shear bands was successfully replicated.

  19. Differential assembly of alpha- and gamma-filagenins into thick filaments in Caenorhabditis elegans

    NASA Technical Reports Server (NTRS)

    Liu, F.; Ortiz, I.; Hutagalung, A.; Bauer, C. C.; Cook, R. G.; Epstein, H. F.

    2000-01-01

    Muscle thick filaments are highly organized supramolecular assemblies of myosin and associated proteins with lengths, diameters and flexural rigidities characteristic of their source. The cores of body wall muscle thick filaments of the nematode Caenorhabditis elegans are tubular structures of paramyosin sub-filaments coupled by filagenins and have been proposed to serve as templates for the assembly of native thick filaments. We have characterized alpha- and gamma-filagenins, two novel proteins of the cores with calculated molecular masses of 30,043 and 19,601 and isoelectric points of 10.52 and 11.49, respectively. Western blot and immunoelectron microscopy using affinity-purified antibodies confirmed that the two proteins are core components. Immunoelectron microscopy of the cores revealed that they assemble with different periodicities. Immunofluorescence microscopy showed that alpha-filagenin is localized in the medial regions of the A-bands of body wall muscle cells whereas gamma-filagenin is localized in the flanking regions, and that alpha-filagenin is expressed in 1.5-twofold embryos while gamma-filagenin becomes detectable only in late vermiform embryos. The expression of both proteins continues throughout later stages of development. C. elegans body wall muscle thick filaments of these developmental stages have distinct lengths. Our results suggest that the differential assembly of alpha- and gamma-filagenins into thick filaments of distinct lengths may be developmentally regulated.

  20. Wall Boundary Layer Measurements for the NASA Langley Transonic Dynamics Tunnel

    NASA Technical Reports Server (NTRS)

    Wieseman, Carol D.; Bennett, Robert M.

    2007-01-01

    Measurements of the boundary layer parameters in the NASA Langley Transonic Dynamics tunnel were conducted during extensive calibration activities following the facility conversion from a Freon-12 heavy-gas test medium to R-134a. Boundary-layer rakes were mounted on the wind-tunnel walls, ceiling, and floor. Measurements were made over the range of tunnel operation envelope in both heavy gas and air and without a model in the test section at three tunnel stations. Configuration variables included open and closed east sidewall wall slots, for air and R134a test media, reentry flap settings, and stagnation pressures over the full range of tunnel operation. The boundary layer thickness varied considerably for the six rakes. The thickness for the east wall was considerably larger that the other rakes and was also larger than previously reported. There generally was some reduction in thickness at supersonic Mach numbers, but the effect of stagnation pressure, and test medium were not extensive.

  1. Electron Microscopy of Staphylococcus aureus Cell Wall Lysis

    PubMed Central

    Virgilio, R.; González, C.; Muñoz, Nubia; Mendoza, Silvia

    1966-01-01

    Virgilio, Rafael (Escuela de Química y Farmacia, Universidad de Chile, Santiago, Chile), C. González, Nubia Muñoz, and Silvia Mendoza. Electron microscopy of Staphylococcus aureus cell wall lysis. J. Bacteriol. 91:2018–2024. 1966.—A crude suspension of Staphylococcus aureus cell walls (strain Cowan III) in buffer solution was shown by electron microscopy to lyse slightly after 16 hr, probably owing to the action of autolysin. The lysis was considerably faster and more intense after the addition of lysozyme. A remarkable reduction in thickness and rigidity of the cell walls, together with the appearance of many irregular protrusions in their outlines, was observed after 2 hr; after 16 hr, there remained only a few recognizable cell wall fragments but many residual particulate remnants. When autolysin was previously inactivated by trypsin, there was a complete inhibition of the lytic action of lysozyme; on the other hand, when autolysin was inactivated by heat and lysozyme was added, a distinct decrease in the thickness of the cell walls was observed, but there was no destruction of the walls. The lytic action of lysozyme, after treatment with hot 5% trichloroacetic acid, gave rise to a marked dissolution of the structure of the cell walls, which became lost against the background, without, however, showing ostensible alteration of wall outlines. From a morphological point of view, the lytic action of autolysin plus lysozyme was quite different from that of trichloroacetic acid plus lysozyme, as shown by electron micrographs, but in both cases it was very intense. This would suggest different mechanisms of action for these agents. Images PMID:5939482

  2. Electron microscopy of Staphylococcus aureus cell wall lysis.

    PubMed

    Virgilio, R; González, C; Muñoz, N; Mendoza, S

    1966-05-01

    Virgilio, Rafael (Escuela de Química y Farmacia, Universidad de Chile, Santiago, Chile), C. González, Nubia Muñoz, and Silvia Mendoza. Electron microscopy of Staphylococcus aureus cell wall lysis. J. Bacteriol. 91:2018-2024. 1966.-A crude suspension of Staphylococcus aureus cell walls (strain Cowan III) in buffer solution was shown by electron microscopy to lyse slightly after 16 hr, probably owing to the action of autolysin. The lysis was considerably faster and more intense after the addition of lysozyme. A remarkable reduction in thickness and rigidity of the cell walls, together with the appearance of many irregular protrusions in their outlines, was observed after 2 hr; after 16 hr, there remained only a few recognizable cell wall fragments but many residual particulate remnants. When autolysin was previously inactivated by trypsin, there was a complete inhibition of the lytic action of lysozyme; on the other hand, when autolysin was inactivated by heat and lysozyme was added, a distinct decrease in the thickness of the cell walls was observed, but there was no destruction of the walls. The lytic action of lysozyme, after treatment with hot 5% trichloroacetic acid, gave rise to a marked dissolution of the structure of the cell walls, which became lost against the background, without, however, showing ostensible alteration of wall outlines. From a morphological point of view, the lytic action of autolysin plus lysozyme was quite different from that of trichloroacetic acid plus lysozyme, as shown by electron micrographs, but in both cases it was very intense. This would suggest different mechanisms of action for these agents.

  3. On/off ratio enhancement in single-walled carbon nanotube field-effect transistor by controlling network density via sonication

    NASA Astrophysics Data System (ADS)

    Jang, Ho-Kyun; Choi, Jun Hee; Kim, Do-Hyun; Kim, Gyu Tae

    2018-06-01

    Single-walled carbon nanotube (SWCNT) is generally used as a networked structure in the fabrication of a field-effect transistor (FET) since it is known that one-third of SWCNT is electrically metallic and the remains are semiconducting. In this case, the presence of metallic paths by metallic SWCNT (m-SWCNT) becomes a significant technical barrier which hinders the networks from achieving a semiconducting behavior, resulting in a low on/off ratio. Here, we report on an easy method of controlling the on/off ratio of a FET where semiconducting SWCNT (s-SWCNT) and m-SWCNT constitute networks between source and drain electrodes. A FET with SWCNT networks was simply sonicated under water to control the on/off ratio and network density. As a result, the FET having an almost metallic behavior due to the metallic paths by m-SWCNT exhibited a p-type semiconducting behavior. The on/off ratio ranged from 1 to 9.0 × 104 along sonication time. In addition, theoretical calculations based on Monte-Carlo method and circuit simulation were performed to understand and explain the phenomenon of a change in the on/off ratio and network density by sonication. On the basis of experimental and theoretical results, we found that metallic paths contributed to a high off-state current which leads to a low on/off ratio and that sonication formed sparse SWCNT networks where metallic paths of m-SWCNT were removed, resulting in a high on/off ratio. This method can open a chance to save the device which has been considered as a failed one due to a metallic behavior by a high network density leading to a low on/off ratio.

  4. Wall Thickness, Pulmonary Hypertension, and Diastolic Filling Abnormalities Predict Response to Postoperative Biventricular Pacing

    PubMed Central

    Brusen, Robin M.; Hahn, Rebecca; Cabreriza, Santos E.; Cheng, Bin; Wang, Daniel Y.; Truong, Wanda; Spotnitz, Henry M.

    2017-01-01

    Objective Post-cardiopulmonary bypass biventricular pacing improves hemodynamics but without clearly defined predictors of response. Based on preclinical studies and prior observations, it was suspected that diastolic dysfunction or pulmonary hypertension is predictive of hemodynamic benefit. Design Randomized controlled study of temporary biventricular pacing after cardiopulmonary bypass. Setting Single-center study at university-affiliated tertiary care hospital. Interventions Patients who underwent bypass with pre-operative ejection fraction ≤40% and QRS duration ≥100 ms or double-valve surgery were enrolled. At 3 time points between separation from bypass and postoperative day 1, pacing delays were varied to optimize hemodynamics. Participants Data from 43 patients were analyzed. Measurements and Main Results Cardiac output and arterial pressure were measured under no pacing, atrial pacing, and biventricular pacing. Preoperative echocardiograms and pulmonary artery catheterizations were reviewed, and measures of both systolic and diastolic function were compared to hemodynamic response. Early after separation, improvement in cardiac output was positively correlated with pulmonary vascular resistance (R2 = 0.97, p < 0.001), ventricle wall thickness (R2 = 0.72, p = 0.002)), and E/e′, a measure of abnormal diastolic ventricular filling velocity (R2 = 0.56, p = 0.04). Similar trends were seen with mean arterial pressure. QRS duration and ejection fraction did not correlate significantly with improvements in hemodynamics. Conclusions There may be an effect of biventricular pacing related to amelioration of abnormal diastolic filling patterns rather than electrical resynchronization in the postoperative state. PMID:25998068

  5. Prenasal thickness to nasal bone length ratio in normal and trisomy 21 fetuses at 11-14 weeks of gestation.

    PubMed

    Manegold-Brauer, Gwendolin; Bourdil, Lucas; Berg, Christoph; Schoetzau, Andreas; Gembruch, Ulrich; Geipel, Annegret

    2015-11-01

    To show the feasibility and to create a reference range for prenasal thickness (PT) and for the PT to nasal bone length (NBL) ratio in normal fetuses at 11-14 gestational weeks and to compare the findings to fetuses with trisomy 21. PT, NBL and PT/NBL ratio were measured retrospectively in stored two-dimensional images of 1155 normal fetuses and 44 fetuses with trisomy 21. Mid-sagittal images were acquired at first trimester ultrasound examinations and were selected from our digital database. The PT increased with CRL from 1.0 mm at 45-mm CRL to 1.6 mm at 84-mm CRL. The mean PT/NBL ratio was 0.6 and was not altered by CRL. The mean PT/NBL ratio in fetuses with trisomy 21 was significantly higher than in normal fetuses (p < 0.0001). For a cut-off value of 0.8 the PT/NBL yielded a sensitivity of 86.4% and a specificity of 98.4% for trisomy 21. The assessment of PT between 11 and 14 gestational weeks is feasible with high intraclass correlation. The PT to NBL ratio seems to be a promising marker for trisomy 21 in the first trimester and was superior to the isolated contribution of NBL and PT measurements. © 2015 John Wiley & Sons, Ltd.

  6. Improving a two-equation eddy-viscosity turbulence model to predict the aerodynamic performance of thick wind turbine airfoils

    NASA Astrophysics Data System (ADS)

    Bangga, Galih; Kusumadewi, Tri; Hutomo, Go; Sabila, Ahmad; Syawitri, Taurista; Setiadi, Herlambang; Faisal, Muhamad; Wiranegara, Raditya; Hendranata, Yongki; Lastomo, Dwi; Putra, Louis; Kristiadi, Stefanus

    2018-03-01

    Numerical simulations for relatively thick airfoils are carried out in the present studies. An attempt to improve the accuracy of the numerical predictions is done by adjusting the turbulent viscosity of the eddy-viscosity Menter Shear-Stress-Transport (SST) model. The modification involves the addition of a damping factor on the wall-bounded flows incorporating the ratio of the turbulent kinetic energy to its specific dissipation rate for separation detection. The results are compared with available experimental data and CFD simulations using the original Menter SST model. The present model improves the lift polar prediction even though the stall angle is still overestimated. The improvement is caused by the better prediction of separated flow under a strong adverse pressure gradient. The results show that the Reynolds stresses are damped near the wall causing variation of the logarithmic velocity profiles.

  7. High-Area-Ratio Rocket Nozzle at High Combustion Chamber Pressure: Experimental and Analytical Validation

    NASA Technical Reports Server (NTRS)

    Jankovsky, Robert S.; Smith, Timothy D.; Pavli, Albert J.

    1999-01-01

    Experimental data were obtained on an optimally contoured nozzle with an area ratio of 1025:1 and on a truncated version of this nozzle with an area ratio of 440:1. The nozzles were tested with gaseous hydrogen and liquid oxygen propellants at combustion chamber pressures of 1800 to 2400 psia and mixture ratios of 3.89 to 6.15. This report compares the experimental performance, heat transfer, and boundary layer total pressure measurements with theoretical predictions of the current Joint Army, Navy, NASA, Air Force (JANNAF) developed methodology. This methodology makes use of the Two-Dimensional Kinetics (TDK) nozzle performance code. Comparisons of the TDK-predicted performance to experimentally attained thrust performance indicated that both the vacuum thrust coefficient and the vacuum specific impulse values were approximately 2.0-percent higher than the turbulent prediction for the 1025:1 configurations, and approximately 0.25-percent higher than the turbulent prediction for the 440:1 configuration. Nozzle wall temperatures were measured on the outside of a thin-walled heat sink nozzle during the test fittings. Nozzle heat fluxes were calculated front the time histories of these temperatures and compared with predictions made with the TDK code. The heat flux values were overpredicted for all cases. The results range from nearly 100 percent at an area ratio of 50 to only approximately 3 percent at an area ratio of 975. Values of the integral of the heat flux as a function of nozzle surface area were also calculated. Comparisons of the experiment with analyses of the heat flux and the heat rate per axial length also show that the experimental values were lower than the predicted value. Three boundary layer rakes mounted on the nozzle exit were used for boundary layer measurements. This arrangement allowed total pressure measurements to be obtained at 14 different distances from the nozzle wall. A comparison of boundary layer total pressure profiles and analytical

  8. [Endoscopic full-thickness resection].

    PubMed

    Meier, B; Schmidt, A; Caca, K

    2016-08-01

    Conventional endoscopic resection techniques such as endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) are powerful tools for the treatment of gastrointestinal (GI) neoplasms. However, those techniques are limited to the superficial layers of the GI wall (mucosa and submucosa). Lesions without lifting sign (usually arising from deeper layers) or lesions in difficult anatomic positions (appendix, diverticulum) are difficult - if not impossible - to resect using conventional techniques, due to the increased risk of complications. For larger lesions (>2 cm), ESD appears to be superior to the conventional techniques because of the en bloc resection, but the procedure is technically challenging, time consuming, and associated with complications even in experienced hands. Since the development of the over-the-scope clips (OTSC), complications like bleeding or perforation can be endoscopically better managed. In recent years, different endoscopic full-thickness resection techniques came to the focus of interventional endoscopy. Since September 2014, the full-thickness resection device (FTRD) has the CE marking in Europe for full-thickness resection in the lower GI tract. Technically the device is based on the OTSC system and combines OTSC application and snare polypectomy in one step. This study shows all full-thickness resection techniques currently available, but clearly focuses on the experience with the FTRD in the lower GI tract.

  9. The Effect of Nozzle Trailing Edge Thickness on Jet Noise

    NASA Technical Reports Server (NTRS)

    Henderson, Brenda; Kinzie, Kevin; Haskin, Henry

    2004-01-01

    The effect of nozzle trailing edge thickness on broadband acoustic radiation and the production of tones is investigated for coannular nozzles. Experiments were performed for a core nozzle trailing edge thickness between 0.38 mm and 3.17 mm. The on-set of discrete tones was found to be predominantly affected by the velocity ratio, the ratio of the fan velocity to the core velocity, although some dependency on trailing edge thickness was also noted. For a core nozzle trailing edge thickness greater than or equal to 0.89 mm, tones were produced for velocity ratios between 0.91 and 1.61. For a constant nozzle trailing edge thickness, the frequency varied almost linearly with the core velocity. The Strouhal number based on the core velocity changed with nozzle trailing edge thickness and varied between 0.16 and 0.2 for the core nozzles used in the experiments. Increases in broadband noise with increasing trailing edge thickness were observed for tone producing and non-tone producing conditions. A variable thickness trailing edge (crenellated) nozzle resulted in no tonal production and a reduction of the broadband trailing edge noise relative to that of the corresponding constant thickness trailing edge.

  10. Theory of Current-Driven Domain Wall Motion

    NASA Astrophysics Data System (ADS)

    Tatara, Gen

    2004-03-01

    Current-induced motion of a domain wall is studied starting from a microscopic Hamiltonian with an exchange interaction between conduction electrons and spins of the wall [1]. With a key observation that the position X and the angle φ0 the wall magnetization forms with the easy plane are the proper collective coordinates to describe its dynamics, it follows straightforwardly that the electric current affects the wall motion in two different ways, in agreement with Berger's pioneering observations[2]. The first is as a force, or momentum transfer, due to the reflection of conduction electrons. This force is proportional to the charge current j and wall resistivity ρ_w, and hence becomes important in thin walls. The other is as a spin torque or spin transfer[3], which is dominant for thick walls where the spin of conduction electron follows the magnetization adiabatically. The motion of a domain wall under a steady current is studied in two limiting cases. In the adiabatic case, we show that even without a pinning force, there is a threshold spin current, j_s^cr∝ K_⊥λ, below which the wall does not move (K_⊥ and λ being the hard-axis magnetic anisotropy and wall thickness, respectively). Below the threshold, the transferred angular momentum is used to shift φ0 and not to the wall motion. The pinning potential V0 affects j_s^cr only if it is very strong, V0 > K_⊥/α, where α is the damping parameter in the Landau-Lifshits-Gilbert equation. Therefore, the critical current for the adiabatic wall does not suffer very much from weak pinning, which is consistent with experimental observations[4]. The wall velocity after depinning is found to be ∝[(j_s/j_s^cr)^2-1]^1/2. In the case of thin wall, driven by a force ∝ ρw j, the critical current density is given by j^cr∝ V_0/ρ_w. In nanocontacts, this is estimated to be ˜ 10^7[A/m^2]. This small critical current would be advantageous for device application. [1] G.Tatara and H.Kohno, cond-mat/0308464

  11. 49 CFR 179.100-6 - Thickness of plates.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-6 Thickness of plates. (a) The wall...

  12. 49 CFR 179.100-6 - Thickness of plates.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-6 Thickness of plates. (a) The wall...

  13. 49 CFR 179.220-6 - Thickness of plates.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-6 Thickness of plates. (a) The wall...

  14. 49 CFR 179.100-6 - Thickness of plates.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-6 Thickness of plates. (a) The wall...

  15. 49 CFR 179.200-6 - Thickness of plates.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-6 Thickness of plates. (a) The wall...

  16. 49 CFR 179.220-6 - Thickness of plates.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-6 Thickness of plates. (a) The wall...

  17. 49 CFR 179.200-6 - Thickness of plates.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-6 Thickness of plates. (a) The wall...

  18. An enhanced VIIRS aerosol optical thickness (AOT) retrieval algorithm over land using a global surface reflectance ratio database

    NASA Astrophysics Data System (ADS)

    Zhang, Hai; Kondragunta, Shobha; Laszlo, Istvan; Liu, Hongqing; Remer, Lorraine A.; Huang, Jingfeng; Superczynski, Stephen; Ciren, Pubu

    2016-09-01

    The Visible/Infrared Imager Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (S-NPP) satellite has been retrieving aerosol optical thickness (AOT), operationally and globally, over ocean and land since shortly after S-NPP launch in 2011. However, the current operational VIIRS AOT retrieval algorithm over land has two limitations in its assumptions for land surfaces: (1) it only retrieves AOT over the dark surfaces and (2) it assumes that the global surface reflectance ratios between VIIRS bands are constants. In this work, we develop a surface reflectance ratio database over land with a spatial resolution 0.1° × 0.1° using 2 years of VIIRS top of atmosphere reflectances. We enhance the current operational VIIRS AOT retrieval algorithm by applying the surface reflectance ratio database in the algorithm. The enhanced algorithm is able to retrieve AOT over both dark and bright surfaces. Over bright surfaces, the VIIRS AOT retrievals from the enhanced algorithm have a correlation of 0.79, mean bias of -0.008, and standard deviation (STD) of error of 0.139 when compared against the ground-based observations at the global AERONET (Aerosol Robotic Network) sites. Over dark surfaces, the VIIRS AOT retrievals using the surface reflectance ratio database improve the root-mean-square error from 0.150 to 0.123. The use of the surface reflectance ratio database also increases the data coverage of more than 20% over dark surfaces. The AOT retrievals over bright surfaces are comparable to MODIS Deep Blue AOT retrievals.

  19. Effect of wall roughness on liquid oscillations damping in rectangular tanks

    NASA Technical Reports Server (NTRS)

    Bugg, F. M.

    1970-01-01

    Tests were conducted in two rectangular glass tanks using silicon carbide grit bonded to walls to determine effect of wall roughness for damping liquid oscillations. Tests included effects of roughness height, roughness location, roughness at various values, amplitude decay, Reynolds number, and boundary layer thickness.

  20. Size Control of Porous Silicon-Based Nanoparticles via Pore-Wall Thinning.

    PubMed

    Secret, Emilie; Leonard, Camille; Kelly, Stefan J; Uhl, Amanda; Cozzan, Clayton; Andrew, Jennifer S

    2016-02-02

    Photoluminescent silicon nanocrystals are very attractive for biomedical and electronic applications. Here a new process is presented to synthesize photoluminescent silicon nanocrystals with diameters smaller than 6 nm from a porous silicon template. These nanoparticles are formed using a pore-wall thinning approach, where the as-etched porous silicon layer is partially oxidized to silica, which is dissolved by a hydrofluoric acid solution, decreasing the pore-wall thickness. This decrease in pore-wall thickness leads to a corresponding decrease in the size of the nanocrystals that make up the pore walls, resulting in the formation of smaller nanoparticles during sonication of the porous silicon. Particle diameters were measured using dynamic light scattering, and these values were compared with the nanocrystallite size within the pore wall as determined from X-ray diffraction. Additionally, an increase in the quantum confinement effect is observed for these particles through an increase in the photoluminescence intensity of the nanoparticles compared with the as-etched nanoparticles, without the need for a further activation step by oxidation after synthesis.

  1. Fiber pigtailed thin wall capillary coupler for excitation of microsphere WGM resonator.

    PubMed

    Wang, Hanzheng; Lan, Xinwei; Huang, Jie; Yuan, Lei; Kim, Cheol-Woon; Xiao, Hai

    2013-07-01

    In this paper, we demonstrate a fiber pigtailed thin wall capillary coupler for excitation of Whispering Gallery Modes (WGMs) of microsphere resonators. The coupler is made by fusion-splicing an optical fiber with a capillary tube and consequently etching the capillary wall to a thickness of a few microns. Light is coupled through the peripheral contact between inserted microsphere and the etched capillary wall. The coupling efficiency as a function of the wall thickness was studied experimentally. WGM resonance with a Q-factor of 1.14 × 10(4) was observed using a borosilicate glass microsphere with a diameter of 71 μm. The coupler operates in the reflection mode and provides a robust mechanical support to the microsphere resonator. It is expected that the new coupler may find broad applications in sensors, optical filters and lasers.

  2. A unified EM approach to bladder wall segmentation with coupled level-set constraints

    PubMed Central

    Han, Hao; Li, Lihong; Duan, Chaijie; Zhang, Hao; Zhao, Yang; Liang, Zhengrong

    2013-01-01

    Magnetic resonance (MR) imaging-based virtual cystoscopy (VCys), as a non-invasive, safe and cost-effective technique, has shown its promising virtue for early diagnosis and recurrence management of bladder carcinoma. One primary goal of VCys is to identify bladder lesions with abnormal bladder wall thickness, and consequently a precise segmentation of the inner and outer borders of the wall is required. In this paper, we propose a unified expectation-maximization (EM) approach to the maximum-a-posteriori (MAP) solution of bladder wall segmentation, by integrating a novel adaptive Markov random field (AMRF) model and the coupled level-set (CLS) information into the prior term. The proposed approach is applied to the segmentation of T1-weighted MR images, where the wall is enhanced while the urine and surrounding soft tissues are suppressed. By introducing scale-adaptive neighborhoods as well as adaptive weights into the conventional MRF model, the AMRF model takes into account the local information more accurately. In order to mitigate the influence of image artifacts adjacent to the bladder wall and to preserve the continuity of the wall surface, we apply geometrical constraints on the wall using our previously developed CLS method. This paper not only evaluates the robustness of the presented approach against the known ground truth of simulated digital phantoms, but further compares its performance with our previous CLS approach via both volunteer and patient studies. Statistical analysis on experts’ scores of the segmented borders from both approaches demonstrates that our new scheme is more effective in extracting the bladder wall. Based on the wall thickness calibrated from the segmented single-layer borders, a three-dimensional virtual bladder model can be constructed and the wall thickness can be mapped on to the model, where the bladder lesions will be eventually detected via experts’ visualization and/or computer-aided detection. PMID:24001932

  3. Numerical Analysis of Film Cooling at High Blowing Ratio

    NASA Technical Reports Server (NTRS)

    El-Gabry, Lamyaa; Heidmann, James; Ameri, Ali

    2009-01-01

    Computational Fluid Dynamics is used in the analysis of a film cooling jet in crossflow. Predictions of film effectiveness are compared with experimental results for a circular jet at blowing ratios ranging from 0.5 to 2.0. Film effectiveness is a surface quantity which alone is insufficient in understanding the source and finding a remedy for shortcomings of the numerical model. Therefore, in addition, comparisons are made to flow field measurements of temperature along the jet centerline. These comparisons show that the CFD model is accurately predicting the extent and trajectory of the film cooling jet; however, there is a lack of agreement in the near-wall region downstream of the film hole. The effects of main stream turbulence conditions, boundary layer thickness, turbulence modeling, and numerical artificial dissipation are evaluated and found to have an insufficient impact in the wake region of separated films (i.e. cannot account for the discrepancy between measured and predicted centerline fluid temperatures). Analyses of low and moderate blowing ratio cases are carried out and results are in good agreement with data.

  4. Light energy transmission and Vickers hardness ratio of bulk-fill resin based composites at different thicknesses cured by a dual-wave or a single-wave light curing unit.

    PubMed

    Santini, Ario; Naaman, Reem Khalil; Aldossary, Mohammed Saeed

    2017-04-01

    To quantify light energy transmission through two bulk-fill resin-based composites and to measure the top to bottom surface Vickers hardness ratio (VHratio) of samples of various incremental thicknesses, using either a single-wave or dual-wave light curing unit (LCU). Tetric EvoCeram Bulk Fill (TECBF) and SonicFill (SF) were studied. Using MARC-RC, the irradiance delivered to the top surface of the samples 2, 3, 4 and 5 mm thick (n= 5 for each thickness) was adjusted to 800 mW/cm2 for 20 seconds (16 J/cm2) using either a single-wave, Bluephase or a dual-wave, Bluephase G2 LCUs. Light energy transmission through to the bottom surface of the specimens was measured at real time using MARC-RC. The Vickers hardness (VH) was determined using Vickers micro hardness tester and the VHratio was calculated. Data were analyzed using a general linear model in Minitab 16; α= 0.05. TECBF was more translucent than SF (P< 0.05). The mean VHratio was higher than 80% in 2, 3 and 4 mm increment thickness for both materials (except for 4 mm TECBF when cured with the dual-wave Bluephase G2). SF showed significantly higher VH ratio than TECBF at all different thickness levels (P< 0.05), except at the 2 mm level (P> 0.05). TECBF showed significantly greater VH ratio when cured with the single-wave Bluephase than when using the dual-wave Bluephase G2 (P< 0.05). The transmission of light energy through to the bottom surface and the VHratio are material dependent. Although TECBF is more translucent than SF, it showed lower VHratio compared to SF when cured with dual-wave Bluephase G2.

  5. Changes in cell wall architecture of wheat coleoptiles grown under continuous hypergravity conditions

    NASA Astrophysics Data System (ADS)

    Wakabayashi, K.; Soga, K.; Kamisaka, S.; Hoson, T.

    Modifications of cell wall structure of wheat coleoptiles in response to continuous hypergravity (300 g) treatment were investigated. Length of coleoptiles exposed to hypergravity for 2-4 days from germination stage was 60-70% of that of 1 g control. The net amounts of cell wall polysaccharides, such as hemicellulose and cellulose, of hypergravity-treated coleoptiles increased as much as those of 1 g control coleoptiles during the incubation period. As a result, the levels of cell wall polysaccharides per unit length of coleoptile, which mean the thickness of cell walls, largely increased under hypergravity conditions. Particularly, the amounts of hemicellulosic polymers with middle molecular mass (0.2-1 MDa) largely increased from day 2 to 3 under hypergravity conditions. The major sugar components of the hemicellulose fraction are arabinose, xylose and glucose. The ratios of arabinose and xylose to glucose were higher in hypergravity-treated coleoptiles than in control coleoptiles. The fractionation of hemicellulosic polymers into the neutral and acidic polymers by the anion-exchange column showed that the levels of acidic polymers (mainly composed of arabinoxylans) in cell walls of hypergravity-treated coleoptiles were higher than those of control coleoptiles. In addition to wall polysaccharides, the amounts of cell wall-bound phenolics, such as ferulic acid and diferulic acid, substantially increased during the incubation period both in 1 g control and hypergravity-treated coleoptiles. Especially, the levels of diferulic acid which cross-links hemicellulosic polymers were higher in hypergravity-treated coleoptiles than in control coleoptiles during the incubation period. These results suggest that hypergravity stimuli from the germination stage bias the type of synthesized hemicellulosic polysaccharides, although they do not restrict the net synthesis of cell wall constituents in wheat coleoptiles. The stimulation of the synthesis of arabinoxylans and of the

  6. [Correlation analysis of cement leakage with volume ratio of intravertebral bone cement to vertebral body and vertebral body wall incompetence in percutaneous vertebroplasty for osteoporotic vertebral compression fractures].

    PubMed

    Liang, De; Ye, Linqiang; Jiang, Xiaobing; Huang, Weiquan; Yao, Zhensong; Tang, Yongchao; Zhang, Shuncong; Jin, Daxiang

    2014-11-01

    To investigate the risk factors of cement leakage in percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fracture (OVCF). Between March 2011 and March 2012, 98 patients with single level OVCF were treated by PVP, and the clinical data were analyzed retrospectively. There were 13 males and 85 females, with a mean age of 77.2 years (range, 54-95 years). The mean disease duration was 43 days (range, 15-120 days), and the mean T score of bone mineral density (BMD) was -3.8 (range, -6.7- -2.5). Bilateral transpedicular approach was used in all the patients. The patients were divided into cement leakage group and no cement leakage group by occurrence of cement leakage based on postoperative CT. Single factor analysis was used to analyze the difference between 2 groups in T score of BMD, operative level, preoperative anterior compression degree of operative vertebrae, preoperative middle compression degree of operative vertebrae, preoperative sagittal Cobb angle of operative vertebrae, preoperative vertebral body wall incompetence, cement volume, and volume ratio of intravertebral bone cement to vertebral body. All relevant factors were introduced to logistic regression analysis to analyze the risk factors of cement leakage. All procedures were performed successfully. The mean operation time was 40 minutes (range, 30-50 minutes), and the mean volume ratio of intravertebral bone cement to vertebral body was 24.88% (range, 7.84%-38.99%). Back pain was alleviated significantly in all the patients postoperatively. All patients were followed up with a mean time of 8 months (range, 6-12 months). Cement leakage occurred in 49 patients. Single factor analysis showed that there were significant differences in the volume ratio of intravertebral bone cement to vertebral body and preoperative vertebral body wall incompetence between 2 groups (P < 0.05), while no significant difference in T score of BMD, operative level, preoperative anterior compression degree of

  7. N-acetylglucosamine affects Cryptococcus neoformans cell-wall composition and melanin architecture.

    PubMed

    Camacho, Emma; Chrissian, Christine; Cordero, Radames J B; Liporagi-Lopes, Livia; Stark, Ruth E; Casadevall, Arturo

    2017-11-01

    Cryptococcus neoformans is an environmental fungus that belongs to the phylum Basidiomycetes and is a major pathogen in immunocompromised patients. The ability of C. neoformans to produce melanin pigments represents its second most important virulence factor, after the presence of a polysaccharide capsule. Both the capsule and melanin are closely associated with the fungal cell wall, a complex structure that is essential for maintaining cell morphology and viability under conditions of stress. The amino sugar N-acetylglucosamine (GlcNAc) is a key constituent of the cell-wall chitin and is used for both N-linked glycosylation and GPI anchor synthesis. Recent studies have suggested additional roles for GlcNAc as an activator and mediator of cellular signalling in fungal and plant cells. Furthermore, chitin and chitosan polysaccharides interact with melanin pigments in the cell wall and have been found to be essential for melanization. Despite the importance of melanin, its molecular structure remains unresolved; however, we previously obtained critical insights using advanced nuclear magnetic resonance (NMR) and imaging techniques. In this study, we investigated the effect of GlcNAc supplementation on cryptococcal cell-wall composition and melanization. C. neoformans was able to metabolize GlcNAc as a sole source of carbon and nitrogen, indicating a capacity to use a component of a highly abundant polymer in the biospherenutritionally. C. neoformans cells grown with GlcNAc manifested changes in the chitosan cell-wall content, cell-wall thickness and capsule size. Supplementing cultures with isotopically 15 N-labelled GlcNAc demonstrated that the exogenous monomer serves as a building block for chitin/chitosan and is incorporated into the cell wall. The altered chitin-to-chitosan ratio had no negative effects on the mother-daughter cell separation; growth with GlcNAc affected the fungal cell-wall scaffold, resulting in increased melanin deposition and assembly. In

  8. N-acetylglucosamine affects Cryptococcus neoformans cell-wall composition and melanin architecture

    PubMed Central

    Camacho, Emma; Chrissian, Christine; Cordero, Radames J. B.; Liporagi-Lopes, Livia; Stark, Ruth E.; Casadevall, Arturo

    2017-01-01

    Cryptococcus neoformans is an environmental fungus that belongs to the phylum Basidiomycetes and is a major pathogen in immunocompromised patients. The ability of C. neoformans to produce melanin pigments represents its second most important virulence factor, after the presence of a polysaccharide capsule. Both the capsule and melanin are closely associated with the fungal cell wall, a complex structure that is essential for maintaining cell morphology and viability under conditions of stress. The amino sugar N-acetylglucosamine (GlcNAc) is a key constituent of the cell-wall chitin and is used for both N-linked glycosylation and GPI anchor synthesis. Recent studies have suggested additional roles for GlcNAc as an activator and mediator of cellular signalling in fungal and plant cells. Furthermore, chitin and chitosan polysaccharides interact with melanin pigments in the cell wall and have been found to be essential for melanization. Despite the importance of melanin, its molecular structure remains unresolved; however, we previously obtained critical insights using advanced nuclear magnetic resonance (NMR) and imaging techniques. In this study, we investigated the effect of GlcNAc supplementation on cryptococcal cell-wall composition and melanization. C. neoformans was able to metabolize GlcNAc as a sole source of carbon and nitrogen, indicating a capacity to use a component of a highly abundant polymer in the biospherenutritionally. C. neoformans cells grown with GlcNAc manifested changes in the chitosan cell-wall content, cell-wall thickness and capsule size. Supplementing cultures with isotopically 15N-labelled GlcNAc demonstrated that the exogenous monomer serves as a building block for chitin/chitosan and is incorporated into the cell wall. The altered chitin-to-chitosan ratio had no negative effects on the mother–daughter cell separation; growth with GlcNAc affected the fungal cell-wall scaffold, resulting in increased melanin deposition and assembly. In

  9. Conjugate Heat Transfer in Rayleigh-Bénard Convection in a Square Enclosure

    PubMed Central

    Hashim, Ishak

    2014-01-01

    Conjugate natural convection-conduction heat transfer in a square enclosure with a finite wall thickness is studied numerically in the present paper. The governing parameters considered are the Rayleigh number (5 × 103 ≤ Ra ≤ 106), the wall-to-fluid thermal conductivity ratio (0.5 ≤ Kr ≤ 10), and the ratio of wall thickness to its height (0.2 ≤ D ≤ 0.4). The staggered grid arrangement together with MAC method was employed to solve the governing equations. It is found that the fluid flow and the heat transfer can be controlled by the thickness of the bottom wall, the thermal conductivity ratio, and the Rayleigh number. PMID:24971390

  10. Compression testing of thick-section composite materials

    NASA Astrophysics Data System (ADS)

    Camponeschi, Eugene T., Jr.

    A compression test fixture suitable for testing of composites up to 1 inch in thickness has been developed with a view to the characterization of the effects of constituents, fiber orientation, and thickness, on the compressive response of composites for naval applications. The in-plane moduli, compression strength, failure mechanisms, and both in-plane and through-thickness Poisson's ratios are shown to be independent of material thickness. The predominant failure mechanisms for both materials, namely kink bands and delaminations, are identical to those reported for composite one-tenth the thickness of those presently tested.

  11. Technical note: Influence of surface roughness and local turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies

    NASA Astrophysics Data System (ADS)

    Li, Guo; Su, Hang; Kuhn, Uwe; Meusel, Hannah; Ammann, Markus; Shao, Min; Pöschl, Ulrich; Cheng, Yafang

    2018-02-01

    Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/Cooney-Kim-Davis (CKD)/Knopf-Pöschl-Shiraiwa (KPS) methods), which has not been fully resolved in earlier studies. Here, we investigate the influence of surface roughness and local turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we derive and propose a critical height δc to evaluate turbulence effects in the design and analysis of coated-wall flow tube experiments. If a geometric coating thickness δg is larger than δc, the roughness elements of the coating may cause local turbulence and result in overestimation of the real uptake coefficient (γ). We further develop modified CKD/KPS methods (i.e., CKD-LT/KPS-LT) to account for roughness-induced local turbulence effects. By combination of the original methods and their modified versions, the maximum error range of γCKD (derived with the CKD method) or γKPS (derived with the KPS method) can be quantified and finally γ can be constrained. When turbulence is generated, γCKD or γKPS can bear large difference compared to γ. Their difference becomes smaller for gas reactants with lower uptake (i.e., smaller γ) and/or for a smaller ratio of the geometric coating thickness to the flow tube radius (δg / R0). On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length, and flow velocity), to ensure not only unaffected laminar flow patterns but also other specific requirements for an individual flow tube

  12. Positive feedback loop for cystitis cystica: the effect of recurrent urinary tract infection on the number of bladder wall mucosa nodules.

    PubMed

    Vrljicak, Kristina; Turudić, Daniel; Bambir, Ivan; Gradiski, Ivan Pavao; Spajić, Borislav; Batinić, Danica; Topalović-Grković, Marija; Spajić, Marija; Batinić, Danko; Milosević, Danko

    2013-12-01

    The main purpose of this study was to demonstrate positive feedback loop between bladder wall nodules (nodules being one of the key diagnostic factors), bladder wall thickness, and recurrent urinary tract infections. Cystitis cystica was diagnosed in 115 prepubertal girls (mean age 7.79 +/- 3.05 years) by optic examination of bladder mucosal nodules and by ultrasonographic measurement of bladder wall thickness. Bladder wall thickness increased with the frequency of recurrent urinary tract infections as well as with the number of nodules on bladder wall mucosa (3.52 +/- 0.522 mm < or = 5 nodules vs. 4.42 +/- 0.429 mm 6-10 nodules vs. 5.20 +/- 0.610 mm > 10 nodules, respectively). Study results suggested that early control of urinary tract infections by chemoprophylaxis could prevent higher grades of bladder wall mucosal changes and consequently shorten the length of chemoprophylaxis.

  13. Reconstruction with a patient-specific titanium implant after a wide anterior chest wall resection

    PubMed Central

    Turna, Akif; Kavakli, Kuthan; Sapmaz, Ersin; Arslan, Hakan; Caylak, Hasan; Gokce, Hasan Suat; Demirkaya, Ahmet

    2014-01-01

    The reconstruction of full-thickness chest wall defects is a challenging problem for thoracic surgeons, particularly after a wide resection of the chest wall that includes the sternum. The location and the size of the defect play a major role when selecting the method of reconstruction, while acceptable cosmetic and functional results remain the primary goal. Improvements in preoperative imaging techniques and reconstruction materials have an important role when planning and performing a wide chest wall resection with a low morbidity rate. In this report, we describe the reconstruction of a wide anterior chest wall defect with a patient-specific custom-made titanium implant. An infected mammary tumour recurrence in a 62-year old female, located at the anterior chest wall including the sternum, was resected, followed by a large custom-made titanium implant. Latissimus dorsi flap and split-thickness graft were also used for covering the implant successfully. A titanium custom-made chest wall implant could be a viable alternative for patients who had large chest wall tumours. PMID:24227881

  14. Effect of metallic walls on dynamos generated by laminar boundary-driven flow in a spherical domain.

    PubMed

    Guervilly, Céline; Wood, Toby S; Brummell, Nicholas H

    2013-11-01

    We present a numerical study of dynamo action in a conducting fluid encased in a metallic spherical shell. Motions in the fluid are driven by differential rotation of the outer metallic shell, which we refer to as "the wall." The two hemispheres of the wall are held in counter-rotation, producing a steady, axisymmetric interior flow consisting of differential rotation and a two-cell meridional circulation with radial inflow in the equatorial plane. From previous studies, this type of flow is known to maintain a stationary equatorial dipole by dynamo action if the magnetic Reynolds number is larger than about 300 and if the outer boundary is electrically insulating. We vary independently the thickness, electrical conductivity, and magnetic permeability of the wall to determine their effect on the dynamo action. The main results are the following: (a) Increasing the conductivity of the wall hinders the dynamo by allowing eddy currents within the wall, which are induced by the relative motion of the equatorial dipole field and the wall. This processes can be viewed as a skin effect or, equivalently, as the tearing apart of the dipole by the differential rotation of the wall, to which the field lines are anchored by high conductivity. (b) Increasing the magnetic permeability of the wall favors dynamo action by constraining the magnetic field lines in the fluid to be normal to the wall, thereby decoupling the fluid from any induction in the wall. (c) Decreasing the wall thickness limits the amplitude of the eddy currents, and is therefore favorable for dynamo action, provided that the wall is thinner than the skin depth. We explicitly demonstrate these effects of the wall properties on the dynamo field by deriving an effective boundary condition in the limit of vanishing wall thickness.

  15. Female urinary incontinence at orgasm: a possible marker of a more severe form of detrusor overactivity. Can ultrasound measurement of bladder wall thickness explain it?

    PubMed

    Serati, Maurizio; Salvatore, Stefano; Cattoni, Elena; Siesto, Gabriele; Soligo, Marco; Braga, Andrea; Sorice, Paola; Cromi, Antonella; Ghezzi, Fabio; Cardozo, Linda; Bolis, Pierfrancesco

    2011-06-01

    Coital incontinence (CI) during orgasm is a form of urinary incontinence possibly because of detrusor overactivity (DO), as the underlying pathophysiological condition. Women with this symptom usually show a pharmacological lower cure rate than those with DO alone. The ultrasound measurement of the bladder wall thickness (BWT) allows an indirect evaluation of detrusor muscle thickness, giving a potential index of detrusor activity. We wanted to understand if CI at orgasm could be a marker of severity of DO by comparing BWT in women with both DO and CI at orgasm vs. women with DO alone. In addition we aimed to confirm if CI during orgasm is related to antimuscarinics treatment failure. This is a prospective cohort study performed in two tertiary urogynecological referral departments, recruiting consecutive patients seeking treatment for symptomatic DO. All patients were thoroughly assessed including physical examination, urodynamic evaluation, and BWT measurement according to the International Continence Society/International Urogynecological Association and ICI recommendations. Solifenacine 5 mg once daily was then prescribed and follow-up was scheduled to evaluate treatment. Multiple logistic regression (MLR) was performed to identify risk factors for treatment failure. Between September 2007 and March 2010, 31 (22.6%) and 106 (77.4%) women with DO with and without CI at orgasm were enrolled. Women complaining of CI at orgasm had significantly higher BWT than the control group (5.8 ± 0.6 mm vs. 5.2 ± 1.2 mm [P=0.007]). In patients with CI at orgasm, the nonresponder rate to antimuscarinics was significantly higher than controls (P=0.01). After MLR, CI at orgasm was the only independent predictor decreasing antimuscarinics efficacy (odds ratio [OR] 3.16 [95% CI 1.22-8.18], P=0.02). Women with DO and CI at orgasm showed a significantly higher BWT values and worse cure rates than women with DO alone. CI at orgasm could be a marker of a more severe form of DO.

  16. The Influence of Layer Thickness-Ratio on Magnetoresistance in La2/3Ca1/3MnO3/La1/3Ca2/3MnO3 Exchange Biased System

    NASA Astrophysics Data System (ADS)

    Gomez, Maria Elena; Milena Diez, Sandra; Cuartas, Lina Maria; Marin, Lorena; Prieto, Pedro

    2012-02-01

    Isothermal magnetic field dependence of the resistance in La2/3Ca1/3MnO3 (F-LCMO)/ La1/3Ca2/3MnO3(AF-LCMO) bilayer and AF-LCMO/F-LCMO/AF-LCMO trilayer at temperatures below N'eel temperature of the antiferromagnetic layer were carried out to study the thickness layers influence on magneto transport properties. We grew multilayers using a high oxygen pressure sputtering technique. We systematically varied the thickness of the F-LCMO layer, tF, maintaining constant the thickness of the AF-LCMO layer, tAF. We studied the influence of the thickness ratio tF/tAF on the ZFC and FC magnetoresistance (MR) loops. HFC was varied from 100 Oe to 400 Oe. We found that MR has hysteretic behavior as observed in [La2/3Ca1/3MnO3/La1/3Ca2/3MnO3]N superlattices, where MR increases with the increasing field from H=0 to a maximum and then it decreases continuously. The position and magnitude of the maximum is not symmetric with respect to the axis H=0 for both FC and ZFC loops. We found that magnetoresistance behavior of the bilayer and trilayer is thickness-ratio dependent for both ZFC and FC loops.

  17. Application of small panel damping measurements to larger walls

    NASA Astrophysics Data System (ADS)

    Hastings, Mardi C.; Godfrey, Richard; Babcock, G. Madison

    1996-05-01

    Damping properties of a viscoelastic material were determined using a standard resonant beam technique. The damping material was then applied to 1 by 2 foot gypsum panels in a constrained layer construction. Damping loss factors in panels with and without the constrained layer were determined based on reverberation times after excitation at third-octave band center frequencies. The constrained damping layer had been designed to increase damping by an order of magnitude above that of a single gypsum panel at 2000 Hz; however, relative to a gypsum panel of the same overall thickness as the panel with the constrained layer, loss factors increased only by a factor of three to five. Next modal damping loss factors in 9 by 14 foot gypsum single and double walls were calculated from the experimentally determined quality factor for each modal resonance. Results showed that below 2500 Hz, modes in 1 by 2 foot gypsum panels had nearly the same damping loss factors as modes in a 9 by 14 foot gypsum wall of the same thickness; however, loss factors for the wall were an order of magnitude lower than those of the 1 by 2 foot panels at frequencies above 2500 Hz, the coincidence frequency for 5/8-inch thick gypsum plates. Thus it was inconclusive whether or not damping loss factors measured using small panels could be used to estimate the effect of a constrained damping layer on transmission loss through a 9 by 14 foot wall unless boundary conditions and modal frequencies were the same for each size.

  18. Slurry wall containment performance: monitoring and modeling of unsaturated and saturated flow.

    PubMed

    Pedretti, Daniele; Masetti, Marco; Marangoni, Tomaso; Beretta, Giovanni Pietro

    2012-01-01

    A specific 2-year program to monitor and test both the vadose zone and the saturated zone, coupled with a numerical analysis, was performed to evaluate the overall performance of slurry wall systems for containment of contaminated areas. Despite local physical confinement (slurry walls keyed into an average 2-m-thick aquitard), for at least two decades, high concentrations of chlorinated solvents (up to 110 mg l(-1)) have been observed in aquifers that supply drinking water close to the city of Milan (Italy). Results of monitoring and in situ tests have been used to perform an unsaturated-saturated numerical model. These results yielded the necessary quantitative information to be used both for the determination of the hydraulic properties of the different media in the area and for the calibration and validation of the numerical model. Backfill material in the shallower part of the investigated aquifer dramatically affects the natural recharge of the encapsulated area. A transient simulation from wet to drought periods highlights a change in the ratio between leakages from lateral barriers that support a specific scenario of water loss through the containment system. The combination of monitoring and modelling allows a reliable estimate of the overall performance of the physical confinement to be made without using any invasive techniques on slurry wall.

  19. Reduction of asymmetric wall force in ITER disruptions with fast current quench

    NASA Astrophysics Data System (ADS)

    Strauss, H.

    2018-02-01

    One of the problems caused by disruptions in tokamaks is the asymmetric electromechanical force produced in conducting structures surrounding the plasma. The asymmetric wall force in ITER asymmetric vertical displacement event (AVDE) disruptions is calculated in nonlinear 3D MHD simulations. It is found that the wall force can vary by almost an order of magnitude, depending on the ratio of the current quench time to the resistive wall magnetic penetration time. In ITER, this ratio is relatively low, resulting in a low asymmetric wall force. In JET, this ratio is relatively high, resulting in a high asymmetric wall force. Previous extrapolations based on JET measurements have greatly overestimated the ITER wall force. It is shown that there are two limiting regimes of AVDEs, and it is explained why the asymmetric wall force is different in the two limits.

  20. Droplet-air collision dynamics: Evolution of the film thickness

    NASA Astrophysics Data System (ADS)

    Opfer, L.; Roisman, I. V.; Venzmer, J.; Klostermann, M.; Tropea, C.

    2014-01-01

    This study is devoted to the experimental and theoretical investigation of aerodynamic drop breakup phenomena. We show that the phenomena of drop impact onto a rigid wall, drop binary collisions, and aerodynamic drop deformation are similar if the correct scaling is applied. Then we use observations of the deforming drop to estimate the evolution of the film thickness of the bag, the value that determines the size of the fine child drops produced by bag breakup. This prediction of film thickness, based on film kinematics, is validated for the initial stage by direct drop thickness measurements and at the latest stage by the data obtained from the velocity of hole expansion in the film. It is shown that the film thickness correlates well with the dimensionless position of the bag apex.

  1. A sub-atmospheric chemical vapor deposition process for deposition of oxide liner in high aspect ratio through silicon vias.

    PubMed

    Lisker, Marco; Marschmeyer, Steffen; Kaynak, Mehmet; Tekin, Ibrahim

    2011-09-01

    The formation of a Through Silicon Via (TSV) includes a deep Si trench etching and the formation of an insulating layer along the high-aspect-ratio trench and the filling of a conductive material into the via hole. The isolation of the filling conductor from the silicon substrate becomes more important for higher frequencies due to the high coupling of the signal to the silicon. The importance of the oxide thickness on the via wall isolation can be verified using electromagnetic field simulators. To satisfy the needs on the Silicon dioxide deposition, a sub-atmospheric chemical vapor deposition (SA-CVD) process has been developed to deposit an isolation oxide to the walls of deep silicon trenches. The technique provides excellent step coverage of the 100 microm depth silicon trenches with the high aspect ratio of 20 and more. The developed technique allows covering the deep silicon trenches by oxide and makes the high isolation of TSVs from silicon substrate feasible which is the key factor for the performance of TSVs for mm-wave 3D packaging.

  2. Turbulent flame-wall interaction: a DNS study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Jackie; Hawkes, Evatt R; Sankaran, Ramanan

    2010-01-01

    A turbulent flame-wall interaction (FWI) configuration is studied using three-dimensional direct numerical simulation (DNS) and detailed chemical kinetics. The simulations are used to investigate the effects of the wall turbulent boundary layer (i) on the structure of a hydrogen-air premixed flame, (ii) on its near-wall propagation characteristics and (iii) on the spatial and temporal patterns of the convective wall heat flux. Results show that the local flame thickness and propagation speed vary between the core flow and the boundary layer, resulting in a regime change from flamelet near the channel centreline to a thickened flame at the wall. This findingmore » has strong implications for the modelling of turbulent combustion using Reynolds-averaged Navier-Stokes or large-eddy simulation techniques. Moreover, the DNS results suggest that the near-wall coherent turbulent structures play an important role on the convective wall heat transfer by pushing the hot reactive zone towards the cold solid surface. At the wall, exothermic radical recombination reactions become important, and are responsible for approximately 70% of the overall heat release rate at the wall. Spectral analysis of the convective wall heat flux provides an unambiguous picture of its spatial and temporal patterns, previously unobserved, that is directly related to the spatial and temporal characteristic scalings of the coherent near-wall turbulent structures.« less

  3. The nonlinear bending response of thin-walled laminated composite cylinders

    NASA Technical Reports Server (NTRS)

    Fuchs, Hannes P.; Hyer, Michael W.

    1992-01-01

    The geometrically nonlinear Donnell shell theory is applied to the problem of stable bending of thin-walled circular cylinders. Responses are computed for cylinders with a radius-to-thickness ratio of 50 and length-to-radius ratios of 1 and 5. Four laminated composite cylinders and an aluminum cylinder are considered. Critical moment estimates are presented for short cylinders for which compression-type buckling behavior is important, and for very long cylinders for which the cross-section flattening, i.e., Brazier effect, is important. A finite element analysis is used to estimate the critical end rotation in addition to establishing the range of validity of the prebuckling analysis. The radial displacement response shows that the character of the boundary layer is significantly influenced by the geometric nonlinearities. Application of a first ply failure analysis using the maximum stress criterion suggests that in nearly all instances material failure occurs before buckling. Failure of the composite cylinders can be attributed to fiber breakage. Striking similarities are seen between the prebuckling displacements of the bending problem and axial compression problem for short cylinders.

  4. Vertical regolith shield wall construction for lunar base applications

    NASA Technical Reports Server (NTRS)

    Kaplicky, Jan; Nixon, David; Wernick, Jane

    1992-01-01

    Lunar bases located on the lunar surface will require permanent protection from radiation and launch ejecta. This paper outlines a method of providing physical protection using lunar regolith that is constructed in situ as a modular vertical wall using specially devised methods of containment and construction. Deployable compartments, reinforced with corner struts, are elevated and filled by a moving gantry. The compartments interlock to form a stable wall. Different wall heights, thicknesses, and plan configurations are achieved by varying the geometry of the individual compartments, which are made from woven carbon fibers. Conventional terrestrial structural engineering techniques can be modified and used to establish the structural integrity and performance of the wall assembly.

  5. Air film cooling in a nonadiabatic wall conical nozzle.

    NASA Technical Reports Server (NTRS)

    Boldman, D. R.; Papell, S. S.; Ehlers, R. C.

    1972-01-01

    Experimental data for an air-film cooled conical nozzle operating with a heated-air main stream and a water-cooled wall confirm the validity of Lieu's (1964) method for correlating film cooling data in the accelerated flow of a nonadiabatic-wall nozzle. The film cooling effectiveness modified for nonadiabatic walls by Lieu can be used to correlate film cooling under the condition that the main-stream to coolant velocity ratio at the slot is about 1. Such a ratio provides the optimum cooling effectiveness.

  6. Gastric wall changes after intragastric balloon placement: a preliminary experience.

    PubMed

    Périssé, Luís Gustavo Santos; Ecbc-Rj, Paulo Cézar Marques Périssé; Ribeiro, Kelson Ferreira

    2016-01-01

    : to evaluate the thickness of the gastric wall at the time of intra gastric balloon (IGB) placement, at the time of its withdrawal and one month after withdrawal. : fifteen morbidly obese patients underwent the introduction of IGB under general anesthesia. In all patients, there was infusion of 500ml of distilled water in the balloon for the test. Measurements of the thickness of the gastric wall were made in the antrum, body and proximal body, using a radial echoendoscope with a frequency of 12MHz and maximum zoom, and its own balloon inflated with 5ml of distilled water. : the presence of IGB led to increased wall thickness of the gastric body by expanding the muscle layer. These changes were apparently transient, since 30 days after the balloon withdrawal there was a tendency to return of the wall thickness values ​​observed before the balloon insertion. : the use of intragastric balloon for the treatment of obesity determines transient increase in the wall thickness of the gastric body caused by expanded muscle layer. avaliar a espessura da parede gástrica no momento do posicionamento do balão intragástrico (BIG), no momento de sua retirada e um mês após a retirada. quinze pacientes obesos mórbidos foram submetidos à introdução de BIG sob anestesia geral. Em todos os pacientes foi feita infusão de 500 ml de água destilada e o balão foi insuflado com 5ml de água destilada. As medidas da espessura da parede gástrica foram feitas no antro, corpo e corpo alto utilizando-se um ecoendoscópio radial com frequência de 12MHz e zoom máximo. a presença do BIG levou ao aumento da espessura da parede do corpo gástrico pelo aumento de espessura da sua camada muscular. Estas alterações são aparentemente transitórias já que após 30 dias da retirada do balão existiu uma tendência de retorno da espessura da parede aos valores observados antes do seu posicionamento. a utilização do balão intragástrico para tratamento da obesidade determina

  7. Cell Wall Remodeling Enzymes Modulate Fungal Cell Wall Elasticity and Osmotic Stress Resistance.

    PubMed

    Ene, Iuliana V; Walker, Louise A; Schiavone, Marion; Lee, Keunsook K; Martin-Yken, Hélène; Dague, Etienne; Gow, Neil A R; Munro, Carol A; Brown, Alistair J P

    2015-07-28

    The fungal cell wall confers cell morphology and protection against environmental insults. For fungal pathogens, the cell wall is a key immunological modulator and an ideal therapeutic target. Yeast cell walls possess an inner matrix of interlinked β-glucan and chitin that is thought to provide tensile strength and rigidity. Yeast cells remodel their walls over time in response to environmental change, a process controlled by evolutionarily conserved stress (Hog1) and cell integrity (Mkc1, Cek1) signaling pathways. These mitogen-activated protein kinase (MAPK) pathways modulate cell wall gene expression, leading to the construction of a new, modified cell wall. We show that the cell wall is not rigid but elastic, displaying rapid structural realignments that impact survival following osmotic shock. Lactate-grown Candida albicans cells are more resistant to hyperosmotic shock than glucose-grown cells. We show that this elevated resistance is not dependent on Hog1 or Mkc1 signaling and that most cell death occurs within 10 min of osmotic shock. Sudden decreases in cell volume drive rapid increases in cell wall thickness. The elevated stress resistance of lactate-grown cells correlates with reduced cell wall elasticity, reflected in slower changes in cell volume following hyperosmotic shock. The cell wall elasticity of lactate-grown cells is increased by a triple mutation that inactivates the Crh family of cell wall cross-linking enzymes, leading to increased sensitivity to hyperosmotic shock. Overexpressing Crh family members in glucose-grown cells reduces cell wall elasticity, providing partial protection against hyperosmotic shock. These changes correlate with structural realignment of the cell wall and with the ability of cells to withstand osmotic shock. The C. albicans cell wall is the first line of defense against external insults, the site of immune recognition by the host, and an attractive target for antifungal therapy. Its tensile strength is conferred by

  8. Investigation of impingement region and wall jets formed by the interaction of high aspect ratio lift jets and a ground plane

    NASA Technical Reports Server (NTRS)

    Kotansky, D. R.; Glaze, L. W.

    1978-01-01

    Flow characteristics of impinging jets emanating from rectangular exit area converging nozzles of exit area aspect ratio four, six, and eight were investigated. Azimuthal distributions of wall jet radial momentum flux in the ground plane were strongly directional and sensitive to rectangular nozzle exit area aspect ratio, jet impingement angle, and height above ground, H/D. Effects of jet exit velocity profile nonuniformities were also investigated. Data from the single nozzle rectangular jet impringement investigations were incorporated into an existing VTOL aircraft ground flow field computer program. It is suggested that this program together with the Douglas Neumann program modified for V/STOL applications may be used for the analysis and prediction of flow fields and resulting forces and moments on multijet V/STOL aircraft hovering in ground effect.

  9. Prenasal Thickness, Prefrontal Space Ratio and Other Facial Profile Markers in First-Trimester Fetuses with Aneuploidies, Cleft Palate, and Micrognathia.

    PubMed

    Bakker, Merel; Pace, Margherita; de Jong-Pleij, Els; Birnie, Erwin; Kagan, Karl-Oliver; Bilardo, Caterina M

    2018-01-01

    To investigate the feasibility and reproducibility of the prenasal thickness (PNT)/nasal bone length (NBL) ratio, maxilla-nasion-mandible (MNM) angle, facial profile line, profile line distance, and prefrontal space ratio (PFSR) in the first trimester of pregnancy, develop normal ranges, and evaluate these markers in abnormal fetuses. All measurements were performed on stored images by two operators. Feasibility, interoperator agreement, and prediction intervals were calculated for all measurements. Feasibility was the highest for the NBL (74.3-79.7%) and the MNM angle (75.7-79.05%). Correlation was good for the NBL, the PNT, and the MNM angle (intraclass correlation coefficient 0.706-0.835). Mean difference between operators was the lowest for the PNT and PFSR (0.03-0.08). Measurements in abnormal fetuses showed that the majority of trisomy 21 fetuses had either an absent nasal bone or a shorter NBL. The PNT and PNT/NBL ratio were above the 97.5th centile in one third of the cases. Fetuses with facial clefts or micrognathia showed on average a large MNM angle (multiple of the median 0.96-5.15). First-trimester facial markers are feasible. The PNT and PNT/NBL ratio were increased in one third of the trisomic fetuses, and the MNM angle in the majority of fetuses with micrognathia and facial clefts. © 2016 S. Karger AG, Basel.

  10. Likelihood ratios for glaucoma diagnosis using spectral-domain optical coherence tomography.

    PubMed

    Lisboa, Renato; Mansouri, Kaweh; Zangwill, Linda M; Weinreb, Robert N; Medeiros, Felipe A

    2013-11-01

    To present a methodology for calculating likelihood ratios for glaucoma diagnosis for continuous retinal nerve fiber layer (RNFL) thickness measurements from spectral-domain optical coherence tomography (spectral-domain OCT). Observational cohort study. A total of 262 eyes of 187 patients with glaucoma and 190 eyes of 100 control subjects were included in the study. Subjects were recruited from the Diagnostic Innovations Glaucoma Study. Eyes with preperimetric and perimetric glaucomatous damage were included in the glaucoma group. The control group was composed of healthy eyes with normal visual fields from subjects recruited from the general population. All eyes underwent RNFL imaging with Spectralis spectral-domain OCT. Likelihood ratios for glaucoma diagnosis were estimated for specific global RNFL thickness measurements using a methodology based on estimating the tangents to the receiver operating characteristic (ROC) curve. Likelihood ratios could be determined for continuous values of average RNFL thickness. Average RNFL thickness values lower than 86 μm were associated with positive likelihood ratios (ie, likelihood ratios greater than 1), whereas RNFL thickness values higher than 86 μm were associated with negative likelihood ratios (ie, likelihood ratios smaller than 1). A modified Fagan nomogram was provided to assist calculation of posttest probability of disease from the calculated likelihood ratios and pretest probability of disease. The methodology allowed calculation of likelihood ratios for specific RNFL thickness values. By avoiding arbitrary categorization of test results, it potentially allows for an improved integration of test results into diagnostic clinical decision making. Copyright © 2013. Published by Elsevier Inc.

  11. Kinetics of the crust thickness development of bread during baking.

    PubMed

    Soleimani Pour-Damanab, Alireza; Jafary, A; Rafiee, Sh

    2014-11-01

    The development of crust thickness of bread during baking is an important aspect of bread quality and shelf-life. Computer vision system was used for measuring the crust thickness via colorimetric properties of bread surface during baking process. Crust thickness had a negative and positive relationship with Lightness (L (*) ) and total color change (E (*) ) of bread surface, respectively. A linear negative trend was found between crust thickness and moisture ratio of bread samples. A simple mathematical model was proposed to predict the development of crust thickness of bread during baking, where the crust thickness was depended on moisture ratio that was described by the Page moisture losing model. The independent variables of the model were baking conditions, i.e. oven temperature and air velocity, and baking time. Consequently, the proposed model had well prediction ability, as the mean absolute estimation error of the model was 7.93 %.

  12. Cyclic Behavior of Low Rise Concrete Shear Walls Containing Recycled Coarse and Fine Aggregates.

    PubMed

    Qiao, Qiyun; Cao, Wanlin; Qian, Zhiwei; Li, Xiangyu; Zhang, Wenwen; Liu, Wenchao

    2017-12-07

    In this study, the cyclic behaviors of low rise concrete shear walls using recycled coarse or fine aggregates were investigated. Eight low rise Recycled Aggregates Concrete (RAC) shear wall specimens were designed and tested under a cyclic loading. The following parameters were varied: replacement percentages of recycled coarse or fine aggregates, reinforcement ratio, axial force ratio and X-shaped rebars brace. The failure characteristics, hysteretic behavior, strength and deformation capacity, strain characteristics and stiffness were studied. Test results showed that the using of the Recycled Coarse Aggregates (RCA) and its replacement ratio had almost no influence on the mechanical behavior of the shear wall; however, the using of Recycled Fine Aggregates (RFA) had a certain influence on the ductility of the shear wall. When the reinforcement ratio increased, the strength and ductility also increased. By increasing the axial force ratio, the strength increased but the ductility decreased significantly. The encased brace had a significant effect on enhancing the RAC shear walls. The experimental maximum strengths were evaluated with existing design codes, it was indicated that the strength evaluation of the low rise RAC shear walls can follow the existing design codes of the conventional concrete shear walls.

  13. Chaos Through-Wall Imaging Radar

    NASA Astrophysics Data System (ADS)

    Xu, Hang; Wang, Bingjie; Zhang, Jianguo; Liu, Li; Li, Ying; Wang, Yuncai; Wang, Anbang

    2017-12-01

    We experimentally demonstrate a chaos through-wall imaging radar using ultra-wideband chaotic-pulse-position modulation (CPPM) microwave signal. The CPPM signal based on logistic map with 1-ns pulse width and 1-GHz bandwidth is implemented by a field programmable gate array (FPGA) and then up-converted as the radar transmitting signal. Two-dimensional image of human objects behind obstacles is obtained by correlation method and back projection algorithm. Our experiments successfully perform through-wall imaging for single and multiple human objects through 20-cm thick wall. The down-range resolution of the proposed radar is 15 cm. Furthermore, the anti-jamming properties of the proposed radar in CPPM jamming, linear frequency-modulated jamming, and Gaussian noise jamming environments are demonstrated by electromagnetic simulations using the finite-difference time-domain. The simulation results show the CPPM microwave signal possesses excellent jamming immunity to the noise and radio frequency interference, which makes it perform superbly in multiradar environments.

  14. Calculation of water equivalent thickness of materials of arbitrary density, elemental composition and thickness in proton beam irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Newhauser, Wayne D.

    2009-03-01

    In proton therapy, the radiological thickness of a material is commonly expressed in terms of water equivalent thickness (WET) or water equivalent ratio (WER). However, the WET calculations required either iterative numerical methods or approximate methods of unknown accuracy. The objective of this study was to develop a simple deterministic formula to calculate WET values with an accuracy of 1 mm for materials commonly used in proton radiation therapy. Several alternative formulas were derived in which the energy loss was calculated based on the Bragg-Kleeman rule (BK), the Bethe-Bloch equation (BB) or an empirical version of the Bethe-Bloch equation (EBB). Alternative approaches were developed for targets that were 'radiologically thin' or 'thick'. The accuracy of these methods was assessed by comparison to values from an iterative numerical method that utilized evaluated stopping power tables. In addition, we also tested the approximate formula given in the International Atomic Energy Agency's dosimetry code of practice (Technical Report Series No 398, 2000, IAEA, Vienna) and stopping power ratio approximation. The results of these comparisons revealed that most methods were accurate for cases involving thin or low-Z targets. However, only the thick-target formulas provided accurate WET values for targets that were radiologically thick and contained high-Z material.

  15. Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

    PubMed

    Luo, Ying; Wang, Jianguo; Liu, Bin; Wang, Zhouli; Yuan, Yahong; Yue, Tianli

    2015-01-01

    The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.

  16. An experimental study of the wall-pressure fluctuations beneath low Reynolds number turbulent boundary layers.

    PubMed

    Van Blitterswyk, Jared; Rocha, Joana

    2017-02-01

    A more complete understanding of the physical relationships, between wall-pressure and turbulence, is required for modeling flow-induced noise and developing noise reduction strategies. In this study, the wall-pressure fluctuations, induced by low Reynolds number turbulent boundary layers, are experimentally studied using a high-resolution microphone array. Statistical characteristics obtained using traditional cross-correlation and cross-spectra analyses are complimented with wall-pressure-velocity cross-spectra and wavelet cross-correlations. Wall-pressure-velocity correlations revealed that turbulent activity in the buffer layer contributes at least 40% of the energy to the wall-pressure spectrum at all measured frequencies. As Reynolds number increases, the low-frequency energy shifts from the buffer layer to the logarithmic layer, as expected for regions of uniform streamwise momentum formed by hairpin packets. Conditional cross-spectra suggests that the majority of broadband wall-pressure energy is concentrated within the packets, with the pressure signatures of individual hairpin vortices estimated to decay on average within traveling ten displacement thicknesses, and the packet signature is retained for up to seven boundary layer thicknesses on average.

  17. Effect of open-label infusion of an apoA-I-containing particle (CER-001) on RCT and artery wall thickness in patients with FHA.

    PubMed

    Kootte, Ruud S; Smits, Loek P; van der Valk, Fleur M; Dasseux, Jean-Louis; Keyserling, Constance H; Barbaras, Ronald; Paolini, John F; Santos, Raul D; van Dijk, Theo H; Dallinga-van Thie, Geesje M; Nederveen, Aart J; Mulder, Willem J M; Hovingh, G Kees; Kastelein, John J P; Groen, Albert K; Stroes, Erik S

    2015-03-01

    Reverse cholesterol transport (RCT) contributes to the anti-atherogenic effects of HDL. Patients with the orphan disease, familial hypoalphalipoproteinemia (FHA), are characterized by decreased tissue cholesterol removal and an increased atherogenic burden. We performed an open-label uncontrolled proof-of-concept study to evaluate the effect of infusions with a human apoA-I-containing HDL-mimetic particle (CER-001) on RCT and the arterial vessel wall in FHA. Subjects received 20 infusions of CER-001 (8 mg/kg) during 6 months. Efficacy was assessed by measuring (apo)lipoproteins, plasma-mediated cellular cholesterol efflux, fecal sterol excretion (FSE), and carotid artery wall dimension by MRI and artery wall inflammation by (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography scans. We included seven FHA patients: HDL-cholesterol (HDL-c), 13.8 [1.8-29.1] mg/dl; apoA-I, 28.7 [7.9-59.1] mg/dl. Following nine infusions in 1 month, apoA-I and HDL-c increased directly after infusion by 27.0 and 16.1 mg/dl (P = 0.018). CER-001 induced a 44% relative increase (P = 0.018) in in vitro cellular cholesterol efflux with a trend toward increased FSE (P = 0.068). After nine infusions of CER-001, carotid mean vessel wall area decreased compared with baseline from 25.0 to 22.8 mm(2) (P = 0.043) and target-to-background ratio from 2.04 to 1.81 (P = 0.046). In FHA-subjects, CER-001 stimulates cholesterol mobilization and reduces artery wall dimension and inflammation, supporting further evaluation of CER-001 in FHA patients. Copyright © 2015 by the American Society for Biochemistry and Molecular Biology, Inc.

  18. Intrauterine growth restriction is associated with persistent aortic wall thickening and glomerular proteinuria during infancy

    PubMed Central

    Zanardo, Vincenzo; Fanelli, Tiziana; Weiner, Gary; Fanos, Vassilios; Zaninotto, Martina; Visentin, Silvia; Cavallin, Francesco; Trevisanuto, Daniele; Cosmi, Erich

    2011-01-01

    Low birth weight, caused either by preterm birth or by intrauterine growth restriction, has recently been associated with increased rates of adult renal and cardiovascular disease. Since aortic intima–media thickening is a noninvasive marker of preclinical vascular disease, we compared abdominal aortic intima–media thickness among intrauterine growth restricted and equivalent gestational age fetuses in utero and at 18 months of age. The relationship between intrauterine growth restriction, fetal aortic thickening, and glomerular function during infancy was measured by enrolling 44 mothers with single-fetus pregnancies at 32 weeks gestation: 23 growth restricted and 21 of appropriate gestational age as controls. Abdominal aortic intima–media thickness was measured by ultrasound at enrollment and again at 18 months of age. Fetuses with intrauterine growth restriction had significantly higher abdominal aortic intima–media thickness compared with age controls when measured both in utero and at 18 months. At 18 months, the median urinary microalbumin and median albumin–creatinine ratio were significantly higher in those infants who experienced intrauterine growth restriction compared to the controls. Our results show that intrauterine growth restriction is associated with persistent aortic wall thickening and significantly higher microalbuminuria during infancy. PMID:21490588

  19. Free form hemispherical shaped charge

    DOEpatents

    Haselman, L.C. Jr.

    1996-06-04

    A hemispherical shaped charge has been modified such that one side of the hemisphere is spherical and the other is aspherical allowing a wall thickness variation in the liner. A further modification is to use an elongated hemispherical shape. The liner has a thick wall at its pole and a thin wall at the equator with a continually decreasing wall thickness from the pole to the equator. The ratio of the wall thickness from the pole to the equator varies depending on liner material and HE shape. Hemispherical shaped charges have previously been limited to spherical shapes with no variations in wall thicknesses. By redesign of the basic liner thicknesses, the jet properties of coherence, stability, and mass distribution have been significantly improved. 8 figs.

  20. Free form hemispherical shaped charge

    DOEpatents

    Haselman, Jr., Leonard C.

    1996-01-01

    A hemispherical shaped charge has been modified such that one side of the hemisphere is spherical and the other is aspherical allowing a wall thickness variation in the liner. A further modification is to use an elongated hemispherical shape. The liner has a thick wall at its pole and a thin wall at the equator with a continually decreasing wall thickness from the pole to the equator. The ratio of the wall thickness from the pole to the equator varies depending on liner material and HE shape. Hemispherical shaped charges have previously been limited to spherical shapes with no variations in wall thicknesses. By redesign of the basic liner thicknesses, the jet properties of coherence, stability, and mass distribution have been significantly improved.

  1. Hygrothermal Anaylsis of Wood-Frame Wall Assemblies in a Mixed-Humid Climate

    Treesearch

    Samuel V. Glass

    2013-01-01

    This study uses a one-dimensional hygrothermal model to investigate the moisture performance of 10 residential wood-frame wall assemblies in a representative mixed-humid climate location of Baltimore, Maryland (climate zone 4A). All the assemblies include oriented strandboard (OSB) sheathing and vinyl siding. The walls differ in stud cavity thickness, level of cavity...

  2. Analysis of the Effect of Osteon Diameter on the Potential Relationship of Osteocyte Lacuna Density and Osteon Wall Thickness

    PubMed Central

    Skedros, John G.; Clark, Gunnar C.; Sorenson, Scott M.; Taylor, Kevin W.; Qiu, Shijing

    2011-01-01

    An important hypothesis is that the degree of infilling of secondary osteons (Haversian systems) is controlled by the inhibitory effect of osteocytes on osteoblasts, which might be mediated by sclerostin (a glycoprotein produced by osteocytes). Consequently, this inhibition could be proportional to cell number: relatively greater repression is exerted by progressively greater osteocyte density (increased osteocytes correlate with thinner osteon walls). This hypothesis has been examined, but only weakly supported, in sheep ulnae. We looked for this inverse relationship between osteon wall thickness (On.W.Th) and osteocyte lacuna density (Ot.Lc.N/B.Ar) in small and large osteons in human ribs, calcanei of sheep, deer, elk, and horses, and radii and third metacarpals of horses. Analyses involved: (1) all osteons, (2) smaller osteons, either ≤150μm diameter or ≤ the mean diameter, and (3) larger osteons (>mean diameter). Significant, but weak, correlations between Ot.Lc.N/B.Ar and On.W.Th/On.Dm (On.Dm = osteon diameter) were found when considering all osteons in limb bones (r values −0.16 to −0.40, p<0.01; resembling previous results in sheep ulnae: r= −0.39, p<0.0001). In larger osteons, these relationships were either not significant (five/seven bone types) or very weak (two/seven bone types). In ribs, a negative relationship was only found in smaller osteons (r= −0.228, p<0.01); this inverse relationship in smaller osteons did not occur in elk calcanei. These results do not provide clear or consistent support for the hypothesized inverse relationship. However, correlation analyses may fail to detect osteocyte-based repression of infilling if the signal is spatially non-uniform (e.g., increased near the central canal). PMID:21809466

  3. Revision of orthovoltage chest wall treatment using Monte Carlo simulations.

    PubMed

    Zeinali-Rafsanjani, B; Faghihi, R; Mosleh-Shirazi, M A; Mosalaei, A; Hadad, K

    2017-01-01

    Given the high local control rates observed in breast cancer patients undergoing chest wall irradiation by kilovoltage x-rays, we aimed to revisit this treatment modality by accurate calculation of dose distributions using Monte Carlo simulation. The machine components were simulated using the MCNPX code. This model was used to assess the dose distribution of chest wall kilovoltage treatment in different chest wall thicknesses and larger contour or fat patients in standard and mid sternum treatment plans. Assessments were performed at 50 and 100 cm focus surface distance (FSD) and different irradiation angles. In order to evaluate different plans, indices like homogeneity index, conformity index, the average dose of heart, lung, left anterior descending artery (LAD) and percentage target coverage (PTC) were used. Finally, the results were compared with the indices provided by electron therapy which is a more routine treatment of chest wall. These indices in a medium chest wall thickness in standard treatment plan at 50 cm FSD and 15 degrees tube angle was as follows: homogeneity index 2.57, conformity index 7.31, average target dose 27.43 Gy, average dose of heart, lung and LAD, 1.03, 2.08 and 1.60 Gy respectively and PTC 11.19%. Assessments revealed that dose homogeneity in planning target volume (PTV) and conformity between the high dose region and PTV was poor. To improve the treatment indices, the reference point was transferred from the chest wall skin surface to the center of PTV. The indices changed as follows: conformity index 7.31, average target dose 60.19 Gy, the average dose of heart, lung and LAD, 3.57, 6.38 and 5.05 Gy respectively and PTC 55.24%. Coverage index of electron therapy was 89% while it was 22.74% in the old orthovoltage method and also the average dose of the target was about 50 Gy but in the given method it was almost 30 Gy. The results of the treatment study show that the optimized standard and mid sternum treatment for different chest

  4. Strength of bolted wood joints with various ratios of member thicknesses

    Treesearch

    Thomas Lee Wilkinson

    1978-01-01

    Procedures have been recommended–such as in the National Design Specification–for design of bolted joints in wood members where the side members are thicker or thinner than half the main member thickness. However, these recommendations have had no experimental verification up to now. The same is true for joints with other than three members. This study experimentally...

  5. Temporary formation of highly conducting domain walls for non-destructive read-out of ferroelectric domain-wall resistance switching memories

    NASA Astrophysics Data System (ADS)

    Jiang, Jun; Bai, Zi Long; Chen, Zhi Hui; He, Long; Zhang, David Wei; Zhang, Qing Hua; Shi, Jin An; Park, Min Hyuk; Scott, James F.; Hwang, Cheol Seong; Jiang, An Quan

    2018-01-01

    Erasable conductive domain walls in insulating ferroelectric thin films can be used for non-destructive electrical read-out of the polarization states in ferroelectric memories. Still, the domain-wall currents extracted by these devices have not yet reached the intensity and stability required to drive read-out circuits operating at high speeds. This study demonstrated non-destructive read-out of digital data stored using specific domain-wall configurations in epitaxial BiFeO3 thin films formed in mesa-geometry structures. Partially switched domains, which enable the formation of conductive walls during the read operation, spontaneously retract when the read voltage is removed, reducing the accumulation of mobile defects at the domain walls and potentially improving the device stability. Three-terminal memory devices produced 14 nA read currents at an operating voltage of 5 V, and operated up to T = 85 °C. The gap length can also be smaller than the film thickness, allowing the realization of ferroelectric memories with device dimensions far below 100 nm.

  6. Study of noise transmission through double wall aircraft windows

    NASA Technical Reports Server (NTRS)

    Vaicaitis, R.

    1983-01-01

    Analytical and experimental procedures were used to predict the noise transmitted through double wall windows into the cabin of a twin-engine G/A aircraft. The analytical model was applied to optimize cabin noise through parametric variation of the structural and acoustic parameters. The parametric study includes mass addition, increase in plexiglass thickness, decrease in window size, increase in window cavity depth, depressurization of the space between the two window plates, replacement of the air cavity with a transparent viscoelastic material, change in stiffness of the plexiglass material, and different absorptive materials for the interior walls of the cabin. It was found that increasing the exterior plexiglass thickness and/or decreasing the total window size could achieve the proper amount of noise reduction for this aircraft. The total added weight to the aircraft is then about 25 lbs.

  7. Angular dependence of Kβ/Kα intensity ratios of thick Ti and Cu pure elements from 10-25 keV electron bombardment

    NASA Astrophysics Data System (ADS)

    Singh, B.; Kumar, S.; Prajapati, S.; Singh, B. K.; Llovet, X.; Shanker, R.

    2018-02-01

    Measurements yielding the first results on angular dependence of Kβ/Kα X-ray intensity ratios of thick Ti (Z = 22) and Cu (Z = 29) targets induced by 10-25 keV electrons are presented. The measurements were done by rotating the target surface around the electron beam direction in the angular detection range 105° ≤ θ ≤ 165° in the reflection mode using an energy dispersive Si PIN photodiode detector. The measured angular dependence of Kβ/Kα intensity ratios is shown to be almost isotropic for Ti and Cu targets for the range of detection angles, 105° ≤ θ ≤ 150°, while there is a very weak increase beyond 150° for both targets. No dependence of Kβ/Kα intensity ratios on impact energy is observed; while on average, the value of the Kβ/Kα X-ray intensity ratio for Cu is larger by about 8% than that for Ti, which indicates a weak Z-dependence of the target. The experimental results are compared with those obtained from PENELOPE MC calculations and from the Evaluated Atomic Data Library (EADL) ratios. These results on Kβ/Kα X-ray intensity ratios are found to be in reasonable agreement in the detection angle range 105° ≤ θ ≤ 150° to within uncertainties, whereas the simulation and experimental results show a very slight increase in the intensity ratio with θ as the latter attains higher values. The results presented in this work provide a direct check on the accuracy of PENELOPE at oblique incidence angles for which there has been a lack of measurements in the literature until now.

  8. Origami-Inspired Folding of Thick, Rigid Panels

    NASA Technical Reports Server (NTRS)

    Trease, Brian P.; Thomson, Mark W.; Sigel, Deborah A.; Walkemeyer, Phillip E.; Zirbel, Shannon; Howell, Larry; Lang, Robert

    2014-01-01

    To achieve power of 250 kW or greater, a large compression ratio of stowed-to-deployed area is needed. Origami folding patterns were used to inspire the folding of a solar array to achieve synchronous deployment; however, origami models are generally created for near-zero-thickness material. Panel thickness is one of the main challenges of origami-inspired design. Three origami-inspired folding techniques (flasher, square twist, and map fold) were created with rigid panels and hinges. Hinge components are added to the model to enable folding of thick, rigid materials. Origami models are created assuming zero (or near zero) thickness. When a material with finite thickness is used, the panels are required to bend around an increasingly thick fold as they move away from the center of the model. The two approaches for dealing with material thickness are to use membrane hinges to connect the panels, or to add panel hinges, or hinges of the same thickness, at an appropriate width to enable folding.

  9. Spaceflight Affects Postnatal Development of the Aortic Wall in Rats

    PubMed Central

    Yamasaki, Masao; Waki, Hidefumi; Miyake, Masao; Nagayama, Tadanori; Miyamoto, Yukako; Wago, Haruyuki; Okouchi, Toshiyasu; Shimizu, Tsuyoshi

    2014-01-01

    We investigated effect of microgravity environment during spaceflight on postnatal development of the rheological properties of the aorta in rats. The neonate rats were randomly divided at 7 days of age into the spaceflight, asynchronous ground control, and vivarium control groups (8 pups for one dam). The spaceflight group rats at 9 days of age were exposed to microgravity environment for 16 days. A longitudinal wall strip of the proximal descending thoracic aorta was subjected to stress-strain and stress-relaxation tests. Wall tensile force was significantly smaller in the spaceflight group than in the two control groups, whereas there were no significant differences in wall stress or incremental elastic modulus at each strain among the three groups. Wall thickness and number of smooth muscle fibers were significantly smaller in the spaceflight group than in the two control groups, but there were no significant differences in amounts of either the elastin or collagen fibers among the three groups. The decreased thickness was mainly caused by the decreased number of smooth muscle cells. Plastic deformation was observed only in the spaceflight group in the stress-strain test. A microgravity environment during spaceflight could affect postnatal development of the morphological and rheological properties of the aorta. PMID:25210713

  10. Measurement of vascular wall attenuation: comparison of CT angiography using model-based iterative reconstruction with standard filtered back-projection algorithm CT in vitro.

    PubMed

    Suzuki, Shigeru; Machida, Haruhiko; Tanaka, Isao; Ueno, Eiko

    2012-11-01

    To compare the performance of model-based iterative reconstruction (MBIR) with that of standard filtered back projection (FBP) for measuring vascular wall attenuation. After subjecting 9 vascular models (actual attenuation value of wall, 89 HU) with wall thickness of 0.5, 1.0, or 1.5 mm that we filled with contrast material of 275, 396, or 542 HU to scanning using 64-detector computed tomography (CT), we reconstructed images using MBIR and FBP (Bone, Detail kernels) and measured wall attenuation at the center of the wall for each model. We performed attenuation measurements for each model and additional supportive measurements by a differentiation curve. We analyzed statistics using analyzes of variance with repeated measures. Using the Bone kernel, standard deviation of the measurement exceeded 30 HU in most conditions. In measurements at the wall center, the attenuation values obtained using MBIR were comparable to or significantly closer to the actual wall attenuation than those acquired using Detail kernel. Using differentiation curves, we could measure attenuation for models with walls of 1.0- or 1.5-mm thickness using MBIR but only those of 1.5-mm thickness using Detail kernel. We detected no significant differences among the attenuation values of the vascular walls of either thickness (MBIR, P=0.1606) or among the 3 densities of intravascular contrast material (MBIR, P=0.8185; Detail kernel, P=0.0802). Compared with FBP, MBIR reduces both reconstruction blur and image noise simultaneously, facilitates recognition of vascular wall boundaries, and can improve accuracy in measuring wall attenuation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  11. Instantaneous Optical Wall-Temperature of Vertical Two-Phase Annular Flow

    NASA Astrophysics Data System (ADS)

    Fehring, Brian; Livingston-Jha, Simon; Morse, Roman; Chan, Jason; Doherty, James; Brueggeman, Colby; Nellis, Gregory; Dressler, Kristofer; Berson, ArganthaëL.; Multiphase Flow Visualization; Analysis Laboratory at University of Wisconsin-Madison Team

    2017-11-01

    We present a non-invasive optical technique for measuring the instantaneous temperature at the inner wall of a flow duct. The technique is used to characterize a fully-developed vertical annular flow of R245fa refrigerant. The test section includes transparent heating windows made of glass coated with fluorine-doped tin-oxide. A 15 mW helium-neon laser is directed through a prism mounted on one of the glass windows and reflected off of the interface between the 150-micron-thick liquid film and the inside wall of the testing section window. The intensity of the laser light reflected at the liquid film-window interface depends on the index of refraction of liquid R245fa, which itself depends on the temperature of the fluid. The intensity of the reflected light is measured using a photodiode and calibrated to a light reflectance model based on the Fresnel equations and Snell's law. Instantaneous temperature data is combined with optical liquid film thickness measurements to calculate the local instantaneous heat transfer coefficient at the wall.

  12. Evaluation of the horizontal-to-vertical spectral ratio (HVSR) seismic method to determine sediment thickness in the vicinity of the South Well Field, Franklin County, OH

    USGS Publications Warehouse

    Haefner, Ralph J.; Sheets, Rodney A.; Andrews, Robert E.

    2011-01-01

    The horizontal-to-vertical spectral ratio (HVSR) seismic method involves analyzing measurements of ambient seismic noise in three dimensions to determine the fundamental site resonance frequency. Resonance is excited by the interaction of surface waves (Rayleigh and Love) and body waves (vertically incident shear) with the high-contrast aconstic impedance boundary at the bedrock-sediment interface. Measurements were made to determine the method's utility for estimating thickness of unconsolidated glacial sediments at 18 locations at the South Well Field, Franklin County, OH, and at six locations in Pickaway County where sediment thickness was already known. Measurements also were made near a high-capacity production well (with pumping on and off) and near a highway and a limestone quarry to examine changes in resonance frequencies over a 20-hour period. Although the regression relation for resonance frequency and sediment thickness had a relatively low [r.sup.2] (0.322), estimates of sediment thickness were, on average, within 14 percent of known thicknesses. Resonance frequencies for pumping on and pumping off were identical, although the amplitude of the peak was nearly double under pumping conditions. Resonance frequency for the 20-hour period did not change, but the amplitude of the peak changed considerably, with a maximum amplitude in the early afternoon and minimum in the very early morning hours. Clay layers within unconsolidated sediments may influence resonance frequency and the resulting regression equation, resulting in underestimation of sediment thickness; however, despite this and other complicating factors, hydrogeologists should consider this method when thickness data are needed for unconsolidated sediments.

  13. Three-dimensional analysis of alveolar wall destruction in the early stage of pulmonary emphysema.

    PubMed

    Kobayashi, Yukihiro; Uehara, Takeshi; Kawasaki, Kenji; Sugano, Mitsutoshi; Matsumoto, Takehisa; Matsumoto, Gou; Honda, Takayuki

    2015-03-01

    The morphological mechanism of alveolar wall destruction during pulmonary emphysema has not been clarified. The aim of this study was to elucidate this process three-dimensionally. Lung specimens from five patients with pulmonary emphysema were used, and five controls with normal alveolar structure were also examined. Sections 150 μm thick were stained with hematoxylin and eosin, elastica, and silver impregnation, and immunostained with selected antibodies. We examined these sections three-dimensionally using a laser confocal microscope and a light microscope. There were only a few Kohn's pores and no fenestrae in the normal alveoli from the controls. In the lungs of the emphysema patients a small rupture appeared in the extremely thin alveolar wall among the alveolar capillaries. This rupture enlarged to form a circle surrounded by the capillaries, which was called an alveolar fenestra. Two neighboring fenestrae fused by breakdown of the collapsed or cord-like capillary between them to form a large fenestra. The large fenestrae fused repeatedly to become larger, and these were bordered by thick elastic fibers constructing an alveolar framework. Alveolar wall destruction during emphysema could start from small ruptures of the alveolar wall that become fenestrae surrounded by capillaries, which fuse repeatedly to become larger fenestrae rimmed with elastic fibers. The alveolar capillary network could initially prevent enlargement of the fenestrae, and the thick elastic fibers constituting the alveolar framework could secondarily prevent destruction of the alveolar wall structure. © 2014 Wiley Periodicals, Inc.

  14. Comparison of lateral abdominal muscle thickness between weightlifters and matched controls.

    PubMed

    Sitilertpisan, Patraporn; Pirunsan, Ubon; Puangmali, Aatit; Ratanapinunchai, Jonjin; Kiatwattanacharoen, Suchart; Neamin, Hudsaleark; Laskin, James J

    2011-11-01

    To compare lateral abdominal muscle thickness between weightlifters and matched controls. A case control study design. University laboratory. 16 female Thai national weightlifters and 16 matched controls participated in this study. Ultrasound imaging with a 12-MHz linear array was used to measure the resting thickness of transversus abdominis (TrA), internal oblique (IO) and total thickness (Total) of lateral abdominal muscle (LAM) on the right side of abdominal wall. The absolute muscle thickness and the relative contribution of each muscle to the total thickness were determined. Weightlifters had significantly thicker absolute TrA and IO muscles than matched controls (p < 0.01). Further, the relative thickness of the IO was significantly greater in weightlifters than matched controls (p < 0.05). The findings of this study suggest that routine Olympic style weight training among female weightlifters appears to result in preferential hypertrophy or adaptation of the IO muscle. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. The rollup of a vortex layer near a wall

    NASA Technical Reports Server (NTRS)

    Jimenez, Javier; Orlandi, Paolo

    1993-01-01

    The behavior of an inviscid vortex layer of non-zero thickness near a wall is studied, both through direct numerical simulation of the two-dimensional vorticity equation at high Reynolds numbers, and using an approximate ordinary nonlinear integro-differential equation which is satisfied in the limit of a thin layer under long-wavelength perturbations. For appropriate initial conditions the layer rolls up and breaks into compact vortices which move along the wall at constant speed. Because of the effect of the wall, they correspond to equilibrium counter-rotating vortex dipoles. This breakup can be related to the disintegration of the initial conditions of the approximate nonlinear dispersive equation into solitary waves. The study is motivated by the formation of longitudinal vortices from vortex sheets in the wall region of a turbulent channel.

  16. Prognostic impact of intestinal wall thickening in hospitalized patients with heart failure.

    PubMed

    Ikeda, Yuki; Ishii, Shunsuke; Fujita, Teppei; Iida, Yuichiro; Kaida, Toyoji; Nabeta, Takeru; Maekawa, Emi; Yanagisawa, Tomoyoshi; Koitabashi, Toshimi; Takeuchi, Ichiro; Inomata, Takayuki; Ako, Junya

    2017-03-01

    Intestine-cardiovascular relationship has been increasingly recognized as a key factor in patients with heart disease. We aimed to identify the relationships among intestinal wall edema, cardiac function, and adverse clinical events in hospitalized heart failure (HF) patients. Abdominal computed tomographic images of 168 hospitalized HF patients were retrospectively investigated for identification of average colon wall thickness (CWT) from the ascending to sigmoid colon. Relationships between average CWT and echocardiographic parameters, blood sampling data, and primary outcomes including readmission for deteriorated HF and all-cause mortality were evaluated. Among the echocardiographic parameters, lower left ventricular diastolic function was correlated with higher average CWT. In multivariate analysis, higher logarithmic C-reactive protein level, lower estimated glomerular filtration rate, lower peripheral blood lymphocyte count, higher E/E' ratio, and extremely higher/lower defecation frequency were independently correlated with higher average CWT. Multivariate Cox-hazard analysis demonstrated that higher average CWT was independently related to higher incidence of primary outcomes. In hospitalized HF patients, increased CWT was associated with lower cardiac performance, and predicted poorer long-term clinical outcomes. Copyright © 2016. Published by Elsevier B.V.

  17. Fabrication of single/multi-walled hybrid buckypaper composites and their enhancement of electromagnetic interference shielding performance

    NASA Astrophysics Data System (ADS)

    Lu, Shaowei; Shao, Junyan; Ma, Keming; Wang, Xiaoqiang; Zhang, Lu; Meng, Qingshi

    2016-11-01

    Multi-walled carbon nanotubes and single-walled carbon nanotubes show great potential for the application as an electromagnetic interference shielding material. In this paper, the electromagnetic interference shielding the effectiveness of a composite surface coated single/multi-walled carbon nanotube hybrid buckypaper was measured, which showed an average shielding effectiveness of ~55 dB with a buckypaper thickness of 50 µm, and bukypaper density of 0.76 g cm-3, it is much higher than other carbon nanotube/resin materials when sample thickness is on the similar order. The structural, specific surface area and conductivity of the buckypapers were examined by field-emission scanning electron microscopy, specific surface area analyzer and four probes resistance tester, respectively.

  18. Experimental and Theoretical Study on Minimum Achievable Foil Thickness during Asymmetric Rolling

    PubMed Central

    Tang, Delin; Liu, Xianghua; Song, Meng; Yu, Hailiang

    2014-01-01

    Parts produced by microforming are becoming ever smaller. Similarly, the foils required in micro-machines are becoming ever thinner. The asymmetric rolling technique is capable of producing foils that are thinner than those produced by the conventional rolling technique. The difference between asymmetric rolling and conventional rolling is the ‘cross-shear’ zone. However, the influence of the cross-shear zone on the minimum achievable foil thickness during asymmetric rolling is still uncertain. In this paper, we report experiments designed to understand this critical influencing factor on the minimum achievable thickness in asymmetric rolling. Results showed that the minimum achievable thickness of rolled foils produced by asymmetric rolling with a rolling speed ratio of 1.3 can be reduced to about 30% of that possible by conventional rolling technique. Furthermore, the minimum achievable thickness during asymmetric rolling could be correlated to the cross-shear ratio, which, in turn, could be related to the rolling speed ratio. From the experimental results, a formula to calculate the minimum achievable thickness was established, considering the parameters cross-shear ratio, friction coefficient, work roll radius, etc. in asymmetric rolling. PMID:25203265

  19. A Reynolds stress model for near-wall turbulence

    NASA Technical Reports Server (NTRS)

    Durbin, P. A.

    1993-01-01

    The paper formulates a tensorially consistent near-wall second-order closure model. Redistributive terms in the Reynolds stress equations are modeled by an elliptic relaxation equation in order to represent strongly nonhomogeneous effects produced by the presence of walls; this replaces the quasi-homogeneous algebraic models that are usually employed, and avoids the need for ad hoc damping functions. The model is solved for channel flow and boundary layers with zero and adverse pressure gradients. Good predictions of Reynolds stress components, mean flow, skin friction, and displacement thickness are obtained in various comparisons to experimental and direct numerical simulation data. The model is also applied to a boundary layer flowing along a wall with a 90-deg, constant-radius, convex bend.

  20. Prenasal thickness-to-nasal bone length ratio: a strong and simple second- and third-trimester marker for trisomy 21.

    PubMed

    De Jong-Pleij, E A P; Vos, F I; Ribbert, L S M; Pistorius, L R; Tromp, E; Bilardo, C M

    2012-02-01

    To study the ratio of prenasal thickness (PT) to nasal bone length (NBL) in normal and trisomy-21 fetuses in the second and third trimesters of pregnancy. The PT and NBL were measured retrospectively in 106 normal fetuses (in three-dimensional (3D) volumes) and in 30 fetuses with trisomy 21 (10 on two-dimensional (2D) images and 20 in 3D volumes). In normal fetuses the mean PT and NBL increased between 15 and 33 weeks' gestation from 2.3 to 6.1 mm (r = 0.85, P < 0.001) and from 3.3 to 9.6 mm (r = 0.87, P < 0.001), respectively. The PT : NBL ratio was stable throughout gestation, with a mean of 0.61 (95% CI, 0.59-0.63; r = - 0.04, P = 0.7). The 5(th) and 95(th) percentiles were 0.48 and 0.80, respectively. In trisomy-21 fetuses the mean PT and NBL increased between 14 and 34 weeks from 3.0 to 9.2 mm (r = 0.86, P < 0.001) and from 1.9 to 7.8 mm (r = 0.85, P < 0.001), respectively. The PT : NBL ratio was significantly higher than in normal fetuses (P < 0.001) but also stable throughout gestation, with a mean of 1.50 (95% CI, 1.20-1.80; r = - 0.35, P = 0.07). Twenty-three (77%) of the 30 fetuses with trisomy 21 had a PT above the 95(th) percentile and 20 (67%) had an NBL below the 5(th) percentile. All the trisomy-21 fetuses had a PT : NBL ratio above the 95(th) percentile. When the 95(th) percentile of the PT : NBL ratio was used as a cut-off value the detection and false positive rates for trisomy 21 were 100 (95% CI, 89-100)% and 5 (95% CI, 2-11)%, respectively. The positive likelihood ratio was 21.2. The PT : NBL ratio is stable in the second and third trimesters of pregnancy in both normal and trisomy-21 fetuses, but all trisomy-21 fetuses in this series had a PT : NBL ratio above the 95(th) percentile. The ratio is therefore a strong marker for trisomy 21. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.

  1. Effect of open-label infusion of an apoA-I-containing particle (CER-001) on RCT and artery wall thickness in patients with FHA[S

    PubMed Central

    Kootte, Ruud S.; Smits, Loek P.; van der Valk, Fleur M.; Dasseux, Jean-Louis; Keyserling, Constance H.; Barbaras, Ronald; Paolini, John F.; Santos, Raul D.; van Dijk, Theo H.; Dallinga-van Thie, Geesje M.; Nederveen, Aart J.; Mulder, Willem J. M.; Hovingh, G. Kees; Kastelein, John J. P.; Groen, Albert K.; Stroes, Erik S.

    2015-01-01

    Reverse cholesterol transport (RCT) contributes to the anti-atherogenic effects of HDL. Patients with the orphan disease, familial hypoalphalipoproteinemia (FHA), are characterized by decreased tissue cholesterol removal and an increased atherogenic burden. We performed an open-label uncontrolled proof-of-concept study to evaluate the effect of infusions with a human apoA-I-containing HDL-mimetic particle (CER-001) on RCT and the arterial vessel wall in FHA. Subjects received 20 infusions of CER-001 (8 mg/kg) during 6 months. Efficacy was assessed by measuring (apo)lipoproteins, plasma-mediated cellular cholesterol efflux, fecal sterol excretion (FSE), and carotid artery wall dimension by MRI and artery wall inflammation by 18F-fluorodeoxyglucose-positron emission tomography/computed tomography scans. We included seven FHA patients: HDL-cholesterol (HDL-c), 13.8 [1.8–29.1] mg/dl; apoA-I, 28.7 [7.9–59.1] mg/dl. Following nine infusions in 1 month, apoA-I and HDL-c increased directly after infusion by 27.0 and 16.1 mg/dl (P = 0.018). CER-001 induced a 44% relative increase (P = 0.018) in in vitro cellular cholesterol efflux with a trend toward increased FSE (P = 0.068). After nine infusions of CER-001, carotid mean vessel wall area decreased compared with baseline from 25.0 to 22.8 mm2 (P = 0.043) and target-to-background ratio from 2.04 to 1.81 (P = 0.046). In FHA-subjects, CER-001 stimulates cholesterol mobilization and reduces artery wall dimension and inflammation, supporting further evaluation of CER-001 in FHA patients. PMID:25561459

  2. Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption

    PubMed Central

    Luo, Ying; Wang, Jianguo; Liu, Bin; Wang, Zhouli; Yuan, Yahong; Yue, Tianli

    2015-01-01

    The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry. PMID:26295574

  3. Changes in optical coherence tomography measurements after orbital wall decompression in dysthyroid optic neuropathy.

    PubMed

    Park, Kyung-Ah; Kim, Yoon-Duck; Woo, Kyung In

    2018-06-01

    The purpose of our study was to assess changes in peripapillary retinal nerve fiber layer (RNFL) thickness after orbital wall decompression in eyes with dysthyroid optic neuropathy (DON). We analyzed peripapillary optical coherence tomography (OCT) images (Cirrus HD-OCT) from controls and patients with DON before and 1 and 6 months after orbital wall decompression. There was no significant difference in mean preoperative peripapillary retinal nerve fiber layer thickness between eyes with DON and controls. The superior and inferior peripapillary RNFL thickness decreased significantly 1 month after decompression surgery compared to preoperative values (p = 0.043 and p = 0.022, respectively). The global average, superior, temporal, and inferior peripapillary RNFL thickness decreased significantly 6 months after decompression surgery compared to preoperative values (p = 0.015, p = 0.028, p = 0.009, and p = 0.006, respectively). Patients with greater preoperative inferior peripapillary RNFL thickness tended to have better postoperative visual acuity at the last visit (p = 0.024, OR = 0.926). Our data revealed a significant decrease in peripapillary RNFL thickness postoperatively after orbital decompression surgery in patients with DON. We also found that greater preoperative inferior peripapillary RNFL thickness was associated with better visual outcomes. We suggest that RNFL thickness can be used as a prognostic factor for DON before decompression surgery.

  4. High rate capacitive performance of single-walled carbon nanotube aerogels

    DOE PAGES

    Van Aken, Katherine L.; Pérez, Carlos R.; Oh, Youngseok; ...

    2015-05-30

    Single-walled carbon nanotube (SWCNT) aerogels produced by critical-point-drying of wet-gel precursors exhibit unique properties, such as high surface-area-to-volume and strength-to-weight ratios. They are free-standing, are binder-free, and can be scaled to thicknesses of more than 1 mm. In this paper, we examine the electric double layer capacitive behavior of these materials using a common room temperature ionic liquid electrolyte, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI). Electrochemical performance is assessed through galvanostatic cycling, cyclic voltammetry and impedance spectroscopy. Results indicate stable capacitive performance over 10,000 cycles as well as an impressive performance at high charge and discharge rates, due to accessible pore networks andmore » enhanced electronic and ionic conductivities of SWCNT aerogels. Finally, these materials can find applications in mechanically compressible and flexible supercapacitor devices with high power requirements.« less

  5. In-Line Ultrasonic Monitoring for Sediments Stuck on Inner Wall of a Polyvinyl Chloride Pipe

    PubMed Central

    2014-01-01

    This research verified the applicability and effectiveness of the ultrasonic monitoring of sediments stuck on the inner wall of polyvinyl chloride (PVC) pipes. For identifying the transmittance of acoustic energy and the speed of sound in the PVC material, the pulse-echo ultrasonic testing was conducted for PVC sheets of different thicknesses. To simulate the solidified sediment, the hot melt adhesive (HMA) was covered on the inner wall of the PVC pipe in different heights. From the experiment, the speeds of sound in the PVC and the HMA materials were obtained as about 2258 and 2000 m/s, respectively. The thickness of the materials was calculated through the signal processing such as taking the absolute value and low pass filtering, the echo detection, and the measurement of the time of flight. The errors between actual and measured thicknesses of PVC sheets were below 5%. In the case of the substance stuck on the inner wall, the errors were below 2.5%. Since the pulse-echo ultrasonic inspection is available on the outer surface and its measurement accuracy was over 95%, it can be an efficient and effective in-service structural health monitoring for the sediment on the wall of PVC pipes. PMID:25243223

  6. Evaluation of the horizontal-to-vertical spectral ratio (HVSR) seismic method to determine sediment thickness in the vicinity of the south well field, Franklin county, OH

    USGS Publications Warehouse

    Haefner, R.J.; Sheets, R.A.; Andrews, R.E.

    2010-01-01

    The horizontal-to-vertical spectral ratio (HVSR) seismic method involves analyzing measurements of ambient seismic noise in three dimensions to determine the fundamental site resonance frequency. Resonance is excited by the interaction of surface waves (Rayleigh and Love) and body waves (vertically incident shear) with the high-contrast acoustic impedance boundary at the bedrock-sediment interface. Measurements were made to determine the method's utility for estimating thickness of unconsolidated glacial sediments at 18 locations at the South Well Field, Franklin County, OH, and at six locations in Pickaway County where sediment thickness was already known. Measurements also were made near a high-capacity production well (with pumping on and off ) and near a highway and a limestone quarry to examine changes in resonance frequencies over a 20-hour period. Although the regression relation for resonance frequency and sediment thickness had a relatively low r 2(0.322), estimates of sediment thickness were, on average, within 14 percent of known thicknesses. Resonance frequencies for pumping on and pumping off were identical, although the amplitude of the peak was nearly double under pumping conditions. Resonance frequency for the 20-hour period did not change, but the amplitude of the peak changed considerably, with a maximum amplitude in the early afternoon and minimum in the very early morning hours. Clay layers within unconsolidated sediments may influence resonance frequency and the resulting regression equation, resulting in underestimation of sediment thickness; however, despite this and other complicating factors, hydrogeologists should consider this method when thickness data are needed for unconsolidated sediments. ?? 2011 by The Ohio Academy of Science. All Rights Reserved.

  7. Endoscopic full-thickness resection: Current status

    PubMed Central

    Schmidt, Arthur; Meier, Benjamin; Caca, Karel

    2015-01-01

    Conventional endoscopic resection techniques such as endoscopic mucosal resection or endoscopic submucosal dissection are powerful tools for treatment of gastrointestinal neoplasms. However, those techniques are restricted to superficial layers of the gastrointestinal wall. Endoscopic full-thickness resection (EFTR) is an evolving technique, which is just about to enter clinical routine. It is not only a powerful tool for diagnostic tissue acquisition but also has the potential to spare surgical therapy in selected patients. This review will give an overview about current EFTR techniques and devices. PMID:26309354

  8. Endoscopic full-thickness resection: Current status.

    PubMed

    Schmidt, Arthur; Meier, Benjamin; Caca, Karel

    2015-08-21

    Conventional endoscopic resection techniques such as endoscopic mucosal resection or endoscopic submucosal dissection are powerful tools for treatment of gastrointestinal neoplasms. However, those techniques are restricted to superficial layers of the gastrointestinal wall. Endoscopic full-thickness resection (EFTR) is an evolving technique, which is just about to enter clinical routine. It is not only a powerful tool for diagnostic tissue acquisition but also has the potential to spare surgical therapy in selected patients. This review will give an overview about current EFTR techniques and devices.

  9. Experimental evaluation of heat transfer on a 1030:1 area ratio rocket nozzle

    NASA Technical Reports Server (NTRS)

    Kacynski, Kenneth J.; Pavli, Albert J.; Smith, Tamara A.

    1987-01-01

    A 1030:1 carbon steel, heat-sink nozzle was tested. The test conditions included a nominal chamber pressure of 2413 kN/sq m and a mixture ratio range of 2.78 to 5.49. The propellants were gaseous oxygen and gaseous hydrogen. Outer wall temperature measurements were used to calculate the inner wall temperature and the heat flux and heat rate to the nozzle at specified axial locations. The experimental heat fluxes were compared to those predicted by the Two-Dimensional Kinetics (TDK) computer model analysis program. When laminar boundary layer flow was assumed in the analysis, the predicted values were within 15 percent of the experimental values for the area ratios of 20 to 975. However, when turbulent boundary layer conditions were assumed, the predicted values were approximately 120 percent higher than the experimental values. A study was performed to determine if the conditions within the nozzle could sustain a laminar boundary layer. Using the flow properties predicted by TDK, the momentum-thickness Reynolds number was calculated, and the point of transition to turbulent flow was predicted. The predicted transition point was within 0.5 inches of the nozzle throat. Calculations of the acceleration parameter were then made to determine if the flow conditions could produce relaminarization of the boundary layer. It was determined that if the boundary layer flow was inclined to transition to turbulent, the acceleration conditions within the nozzle would tend to suppress turbulence and keep the flow laminar-like.

  10. Experimental evaluation of heat transfer on a 1030:1 area ratio rocket nozzle

    NASA Technical Reports Server (NTRS)

    Kacynski, Kenneth J.; Pavli, Albert J.; Smith, Tamara A.

    1987-01-01

    A 1030:1 carbon steel, heat-sink nozzle was tested. The test conditions included a nominal chamber pressure of 2413 kN/sq m and a mixture ratio range of 2.78 to 5.49. The propellants were gaseous oxygen and gaseous hydrogen. Outer wall temperature measurements were used to calculate the inner wall temperature and the heat flux and heat rate to the nozzle at specified axial locations. The experimental heat fluxes were compared to those predicted by the Two-Dimensional Kinetics (TDK) computer model analysis program. When laminar boundary layer flow was assumed in the analysis, the predicted values were within 15% of the experimental values for the area ratios of 20 to 975. However, when turbulent boundary layer conditions were assumed, the predicted values were approximately 120% higher than the experimental values. A study was performed to determine if the conditions within the nozzle could sustain a laminar boundary layer. Using the flow properties predicted by TDK, the momentum-thickness Reynolds number was calculated, and the point of transition to turbulent flow was predicted. The predicted transition point was within 0.5 inches of the nozzle throat. Calculations of the acceleration parameter were then made to determine if the flow conditions could produce relaminarization of the boundary layer. It was determined that if the boundary layer flow was inclined to transition to turbulent, the acceleration conditions within the nozzle would tend to suppress turbulence and keep the flow laminar-like.

  11. Spin-wave wavelength down-conversion at thickness steps

    NASA Astrophysics Data System (ADS)

    Stigloher, Johannes; Taniguchi, Takuya; Madami, Marco; Decker, Martin; Körner, Helmut S.; Moriyama, Takahiro; Gubbiotti, Gianluca; Ono, Teruo; Back, Christian H.

    2018-05-01

    We report a systematic experimental study on the refraction and reflection of magnetostatic spin-waves at a thickness step between two Permalloy films of different thickness. The transmitted spin-waves for the transition from a thick film to a thin film have a higher wave vector compared to the incoming waves. Consequently, such systems may find use as passive wavelength transformers in magnonic networks. We investigate the spin-wave transmission behavior by studying the influence of the external magnetic field, incident angle, and thickness ratio of the films using time-resolved scanning Kerr microscopy and micro-focused Brillouin light scattering.

  12. Carotid artery thickness is associated with chronic use of highly active antiretroviral therapy in patients infected with human immunodeficiency virus: A 3.0 Tesla magnetic resonance imaging study.

    PubMed

    LaBounty, T M; Hardy, W D; Fan, Z; Yumul, R; Li, D; Dharmakumar, R; Conte, A Hernandez

    2016-08-01

    While patients with HIV infection have an elevated stroke risk, ultrasound studies of carotid artery wall thickness have reported variable results. We hypothesized that subjects with HIV infection on chronic highly active antiretroviral therapy (HAART) would have increased carotid artery wall thickness by magnetic resonance imaging (MRI). This cross-sectional study compared carotid artery wall thickness between 26 individuals infected with HIV on chronic HAART and 20 controls, without HIV infection but with similar cardiovascular risk factors, using 3.0-T noncontrast MRI. Inclusion criteria included male gender, age 35-55 years, and chronic HAART (≥ 3 years) among HIV-seropositive subjects; those with known cardiovascular disease or diabetes were excluded. Between subjects with HIV infection and controls, there were no differences in mean (±SD) age (47.8 ± 5.0 vs. 47.8 ± 4.7 years, respectively; P = 0.19) or cardiovascular risk factors (P > 0.05 for each). Mean (±SD) wall thickness was increased in those with HIV infection vs. controls for the left (0.88 ± 0.08 vs. 0.83 ± 0.08 mm, respectively; P = 0.03) and right (0.90 ± 0.10 vs. 0.85 ± 0.07 mm, respectively; P = 0.046) common carotid arteries. Among individuals with HIV infection, variables associated with increased mean carotid artery wall thickness included lipoaccumulation [+0.09 mm; 95% confidence interval (CI) 0.03-0.14 mm; P = 0.003], Framingham risk score ≥ 5% (+0.07 mm; 95% CI 0.01-0.12; P = 0.02 mm), and increased duration of protease inhibitor therapy (+0.03 mm per 5 years; 95% CI 0.01-0.06 mm; P = 0.02). Individuals with HIV infection on chronic HAART had increased carotid artery wall thickness as compared to similar controls. In subjects with HIV infection, the presence of lipoaccumulation and longer duration of protease inhibitor therapy were associated with greater wall thickness. © 2015 British HIV Association.

  13. Subcutaneous adipose tissue thickness in adults - correlation with BMI and recommendations for pen needle lengths for subcutaneous self-injection.

    PubMed

    Ludescher, Burkhard; Rommel, Marc; Willmer, Tobias; Fritsche, Andreas; Schick, Fritz; Machann, Juergen

    2011-12-01

    One of the aims of a subcutaneous (SC) injection is to avoid intradermal or intramuscular injections. Pen systems are an alternative solution to single-use syringes and have become standard for example diabetes therapy. Shorter and smaller needles minimize pain and the risk of intramuscular injections. The thickness of subcutaneous adipose tissue (SCAT) varies with position and with body mass index (BMI). The aim of this study was the creation of a map of SCAT thickness at typical spots for SC self-injection. MRI scans of 116 prospectively enroled volunteers (56 men and 60 women) were analysed. SCAT thickness was determined at 17 spots over the abdominal wall, left thigh, buttocks and upper arm, typical sites for subcutaneous self-injection. SCAT thicknesses were correlated with BMI and waist-to-hip ratio (WHR), and a linear curve fit was performed. The best fitting linear functions for the prediction of the SCAT thickness dependent on BMI and WHR were derived. Correlations between SCAT and BMI were higher (0·67-0·21) than with WHR (-0·67 to 0·09). In women, correlation coefficients between SCAT data at the abdomen and BMI/WHR were higher than in men. On the other hand, data showed better correlations at the extremities in men. The data, with correlation between BMI and fat thickness at different injection sites in relation to gender, provide guidance in selecting an adequate pen needle length for deep and safe subcutaneous self-injection. WHR was a much weaker predictor when compared to BMI. © 2011 Blackwell Publishing Ltd.

  14. Modeling thermal performance of exterior walls retrofitted from insulation and modified laterite based bricks materials

    NASA Astrophysics Data System (ADS)

    Wati, Elvis; Meukam, Pierre; Damfeu, Jean Claude

    2017-12-01

    Uninsulated concrete block walls commonly found in tropical region have to be retrofitted to save energy. The thickness of insulation layer used can be reduced with the help of modified laterite based bricks layer (with the considerably lower thermal conductivity than that of concrete block layer) during the retrofit building fabrics. The aim of this study is to determine the optimum location and distribution of different materials. The investigation is carried out under steady periodic conditions under the climatic conditions of Garoua in Cameroon using a Simulink model constructed from H-Tools (the library of Simulink models). Results showed that for the continuous air-conditioned space, the best wall configuration from the maximum time lag, minimum decrement factor and peak cooling transmission load perspective, is dividing the insulation layer into two layers and placing one at the exterior surface and the other layer between the two different massive layers with the modified laterite based bricks layer at the interior surface. For intermittent cooling space, the best wall configuration from the minimum energy consumption depends on total insulation thickness. For the total insulation thickness less than 8 cm approximately, the best wall configuration is placing the half layer of insulation material at the interior surface and the other half between the two different massive layers with the modified earthen material at the exterior surface. Results also showed that, the optimum insulation thickness calculated from the yearly cooling transmission (estimated only during the occupied period) and some economic considerations slightly depends on the location of that insulation.

  15. On the three-dimensional instability of laminar boundary layers on concave walls

    NASA Technical Reports Server (NTRS)

    Gortler, Henry

    1954-01-01

    A study is made of the stability of laminar boundary-layer profiles on slightly curved walls relative to small disturbances that result from vortices whose axes are parallel to the principal direction of flow. The result is an eigenvalue problem by which, for a given undisturbed flow at a prescribed wall, the amplification or decay is computed for each Reynolds number and each vortex thickness. For neutral disturbances (zero amplification) a critical Reynolds number is determined for each vortex distribution. The numerical calculation produces amplified disturbances on concave walls only.

  16. Full-Thickness Reconstruction with Pedicle Flap and Diced Homologous Cartilage Over the Pericardium Complicated. Cardiac Arrest

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rees, Thomas D.

    1961-01-01

    Successful repair by plastic surgery of nonhealing ulceration of the chest wall, induced by radiotherapy for breast cancer, is described. Reconstruction of the chest wali defect by pedicle flap coverage was carried out. Radiation injury extended through the entire thickness of the chest wall and osteoradionecrosis of the ribs was present. Reconstruction with thoracoabdominal tube was considered to be the best technique, so a 4- by 9-in. tube pedicle was constructed. The underlying donor wound of the pedicle was covered with a split- thickness skin graft. Healing was without incident, and approximates 3 weeks after formation, the inferior end ofmore » this tube pedicle was migrated to the left epigastrium as an intermediate step. Healing was uncomplicated, and the lateral attachment of the pedicle was partially severed. Three weeks later, resection of all avascular tissue along with portions of the fourth and fifth ribs was carried out. This created a full-thickness chest wall defect measuring 4 by 8 in., with the anterior surface of the pericardial sac exposed in the wound. The end of the abdominal tube pedicle was elevated from its bed, rotated into position, and sutured to the healthy margins of the chest wall defect. The exposed subcutaneous fat of the undersurface of the pedicle was placed in juxtaposition to the pericardium. A split-thickness skin graft was cut from the skin of the left thigh and draped over the pedicle flap donor wound. All sutured wounds healed per primum and the entire skin graft survived. The inferior inset of the tube pedicle was cut free and the pedicle flap was tailored into position 6 weeks later. The patient was discharged from the hospital in good condition and engaged in normal activities. An attempt was made to provide protection for the heart beneath the pedicle inset by introduction of diced homologous cartilage grafts, just beneath the skin of the pedicle flap. This healed with the formation of a thick fibrocartilaginous

  17. Current-induced domain wall motion in permalloy nanowires with a rectangular cross-section

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ai, J. H.; Miao, B. F.; Sun, L.

    2011-11-01

    We performed micromagnetic simulations of the current-induced domain wall motion in permalloy nanowires with rectangular cross-section. In the absence of the nonadiabatic spin-transfer term, a threshold current, J{sub c} is required to drive the domain wall moving continuously. We find that J{sub c} is proportional to the maximum cross product of the demagnetization field and magnetization orientation of the domain wall and the domain wall width. With varying both the wire thickness and width, a minimum threshold current in the order of 10{sup 6} A/cm{sup 2} is obtained when the thickness is equivalent to the wire width. With the nonadiabaticmore » spin-transfer term, the calculated domain wall velocity {nu} equals to the adiabatic spin transfer velocity u when the current is far above the Walker limit J{sub w}. Below J{sub w}, {nu}=({beta}/{alpha})u, where {beta} is the nonadiabatic parameter and {alpha} is the damping factor. For different {beta}, we find the Walker limit can be scaled as J{sub w}=({alpha}/{beta}-{alpha})J{sub c}. Our simulations agree well with the one dimensional analytical calculation, suggesting the findings are the general behaviors of the systems in this particular geometry.« less

  18. Increased Airway Wall Thickness is Associated with Adverse Longitudinal First-Second Forced Expiratory Volume Trajectories of Former World Trade Center workers.

    PubMed

    de la Hoz, Rafael E; Liu, Xiaoyu; Doucette, John T; Reeves, Anthony P; Bienenfeld, Laura A; Wisnivesky, Juan P; Celedón, Juan C; Lynch, David A; San José Estépar, Raúl

    2018-05-24

    Occupational exposures at the WTC site after September 11, 2001 have been associated with several presumably inflammatory lower airway diseases. In this study, we describe the trajectories of expiratory air flow decline, identify subgroups with adverse progression, and investigate the association of a quantitative computed tomography (QCT) imaging measurement of airway wall thickness, and other risk factors for adverse progression. We examined the trajectories of expiratory air flow decline in a group of 799 former WTC workers and volunteers with QCT-measured (with two independent systems) wall area percent (WAP) and at least 3 periodic spirometries. We calculated individual regression lines for first-second forced expiratory volume (FEV 1 ), identified subjects with rapidly declining and increasing ("gainers"), and compared them to subjects with normal and "stable" FEV 1 decline. We used multivariate logistic regression to model decliner vs. stable trajectories. The mean longitudinal FEV 1 slopes for the entire study population, and its stable, decliner, and gainer subgroups were, respectively, - 35.8, - 8, - 157.6, and + 173.62 ml/year. WAP was associated with "decliner" status (OR adj 1.08, 95% CI 1.02, 1.14, per 5% increment) compared to stable. Age, weight gain, baseline FEV 1 percent predicted, bronchodilator response, and pre-WTC occupational exposures were also significantly associated with accelerated FEV 1 decline. Analyses of gainers vs. stable subgroup showed WAP as a significant predictor in unadjusted but not consistently in adjusted analyses. The apparent normal age-related rate of FEV 1 decline results from averaging widely divergent trajectories. WAP is significantly associated with accelerated air flow decline in WTC workers.

  19. Evaluation of Strains and Thicknesses of Pipe Elbows on the Basis of Expressions Resulting from the Eudirective for the Case of Large and Small Deformations

    NASA Astrophysics Data System (ADS)

    Śloderbach, Z.

    2017-12-01

    The relations to calculate the maximum value of strains in processes of bending tubes on benders, in stretched layers of tubes, are presented in this work on the basis of the EU-Directive concerning production of pressure equipment. It has been shown that for large deformations that occur during bending of the pipes on knees, logarithmic strain measures (real) and relative strain measures give different values of strain but equal wall thicknesses in the bending zone. Logarithmic measures are frequently used in engineering practice and are valid for large and small deformations. Reverse expressions were also derived to calculate the required initial wall thickness of the tube to be bent, in order to obtain the desired wall thickness of the knee after bending.

  20. Experimental study on the heat transfer characteristics of a nuclear reactor containment wall cooled by gravitationally falling water

    NASA Astrophysics Data System (ADS)

    Pasek, Ari D.; Umar, Efrison; Suwono, Aryadi; Manalu, Reinhard E. E.

    2012-06-01

    Gravitationally falling water cooling is one of mechanism utilized by a modern nuclear Pressurized Water Reactor (PWR) for its Passive Containment Cooling System (PCCS). Since the cooling is closely related to the safety, water film cooling characteristics of the PCCS should be studied. This paper deals with the experimental study of laminar water film cooling on the containment model wall. The influences of water mass flow rate and wall heat rate on the heat transfer characteristic were studied. This research was started with design and assembly of a containment model equipped with the water cooling system, and calibration of all measurement devices. The containment model is a scaled down model of AP 1000 reactor. Below the containment steam is generated using electrical heaters. The steam heated the containment wall, and then the temperatures of the wall in several positions were measure transiently using thermocouples and data acquisition. The containment was then cooled by falling water sprayed from the top of the containment. The experiments were done for various wall heat rate and cooling water flow rate. The objective of the research is to find the temperature profile along the wall before and after the water cooling applied, prediction of the water film characteristic such as means velocity, thickness and their influence to the heat transfer coefficient. The result of the experiments shows that the wall temperatures significantly drop after being sprayed with water. The thickness of water film increases with increasing water flow rate and remained constant with increasing wall heat rate. The heat transfer coefficient decreases as film mass flow rate increase due to the increases of the film thickness which causes the increasing of the thermal resistance. The heat transfer coefficient increases slightly as the wall heat rate increases. The experimental results were then compared with previous theoretical studied.

  1. Axion domain wall baryogenesis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Daido, Ryuji; Kitajima, Naoya; Takahashi, Fuminobu, E-mail: daido@tuhep.phys.tohoku.ac.jp, E-mail: kitajima@tuhep.phys.tohoku.ac.jp, E-mail: fumi@tuhep.phys.tohoku.ac.jp

    2015-07-01

    We propose a new scenario of baryogenesis, in which annihilation of axion domain walls generates a sizable baryon asymmetry. Successful baryogenesis is possible for a wide range of the axion mass and decay constant, m ≅ 10{sup 8}–10{sup 13} GeV and f ≅ 10{sup 13}–10{sup 16} GeV . Baryonic isocurvature perturbations are significantly suppressed in our model, in contrast to various spontaneous baryogenesis scenarios in the slow-roll regime. In particular, the axion domain wall baryogenesis is consistent with high-scale inflation which generates a large tensor-to-scalar ratio within the reach of future CMB B-mode experiments. We also discuss the gravitational waves produced by the domainmore » wall annihilation and its implications for the future gravitational wave experiments.« less

  2. Correlation of root dentin thickness and length of roots in mesial roots of mandibular molars.

    PubMed

    Dwivedi, Shweta; Dwivedi, Chandra Dhar; Mittal, Neelam

    2014-09-01

    The purpose of this study was to analyze the relation of tooth length and distal wall thickness of mesial roots in mandibular molars at different locations (ie, 2 mm below the furcation and at the junction between the middle and apical third). Forty-five mandibular first molars were taken, and the length of each tooth was measured. Then, specimens were divided into three groups according to their length: group I-long (24.2 mm ± 1.8), group II-medium (21 mm ± 1.5) and group III-short (16.8 mm ± 1.8). mesial root of each marked at two levels - at 2 mm below the furcation as well as at junction of apical and middle third of roots. The minimum thickness of the distal root dentine associated with the buccal and lingual canals of the mesial roots was measured, The distance between the buccal and lingual canals and the depth of concavity in the distal surface of the mesial roots were also measured. Statistical analysis was performed by using analysis of variance and the Student-Newman-Keuls test. The minimum thickness of the distal wall of the mesiobuccal canal was significantly different (P < .001) between groups 1 (long) and 3 (short). Distal wall thickness of the mesiobuccal root and distal concavity of the mesial root of mandibular first molars were found to be thinner in longer teeth compared with shorter teeth. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  3. Accommodating Thickness in Origami-Based Deployable Arrays

    NASA Technical Reports Server (NTRS)

    Zirbel, Shannon A.; Magleby, Spencer P.; Howell, Larry L.; Lang, Robert J.; Thomson, Mark W.; Sigel, Deborah A.; Walkemeyer, Phillip E.; Trease, Brian P.

    2013-01-01

    The purpose of this work is to create deployment systems with a large ratio of stowed-to-deployed diameter. Deployment from a compact form to a final flat state can be achieved through origami-inspired folding of panels. There are many models capable of this motion when folded in a material with negligible thickness; however, when the application requires the folding of thick, rigid panels, attention must be paid to the effect of material thickness not only on the final folded state, but also during the folding motion (i.e., the panels must not be required to flex to attain the final folded form). The objective is to develop new methods for deployment from a compact folded form to a large circular array (or other final form). This paper describes a mathematical model for modifying the pattern to accommodate material thickness in the context of the design, modeling, and testing of a deployable system inspired by an origami six-sided flasher model. The model is demonstrated in hardware as a 1/20th scale prototype of a deployable solar array for space applications. The resulting prototype has a ratio of stowed-to-deployed diameter of 9.2 (or 1.25 m deployed outer diameter to 0.136 m stowed outer diameter).

  4. Growth and cell wall changes in stem organs under microgravity and hypergravity conditions

    NASA Astrophysics Data System (ADS)

    Hoson, Takayuki; Soga, Kouichi; Wakabayashi, Kazuyuki; Kamisaka, Seiichiro

    Gravity strongly influences plant growth and development, which is fundamentally brought about by modifications to the properties of the cell wall. We have examined the changes in growth and cell wall properties in seedling organs under hypergravity conditions produced by centrifugation and under microgravity conditions in space. Hypergravity stimuli have been shown to decrease the growth rate of various seedling organs. When hypergravity suppressed elongation growth, a decrease in cell wall extensibility (an increase in cell wall rigidity) was induced. Hypergravity has also been shown to increase cell wall thickness in various mate-rials. In addition, a polymerization of certain matrix polysaccharides was brought about by hypergravity: in dicotyledons hypergravity increased the molecular size of xyloglucans, whereas hypergravity increased that of 1,3,1,4-β-glucans in monocotyledonous Gramineae. These mod-ifications to cell wall metabolism may be responsible for a decrease in cell wall extensibility, leading to growth suppression under hypergravity conditions. How then does microgravity in-fluence growth and cell wall properties? Here, there was a possibility that microgravity might induce changes similar to those by hypergravity, because plants have evolved and adapted to 1 g condition for more than 400 million years. However, the changes observed under microgravity conditions in space were just opposite to those induced by hypergravity: stimulation of elonga-tion growth, an increase in cell wall extensibility, and a decrease in cell wall thickness as well as depolymerization of cell wall polysaccharides were brought about in space. Furthermore, growth and cell wall properties varied in proportion to the logarithm of the magnitude of grav-ity in the range from microgravity to hypergravity, as shown in the dose-response relation in light and hormonal responses. Thus, microgravity may be a `stress-less' environment for plant seedlings to grow and develop

  5. Scale resolving computation of submerged wall jets on flat wall with different roughness heights

    NASA Astrophysics Data System (ADS)

    Paik, Joongcheol; Bombardelli, Fabian

    2014-11-01

    Scale-adaptive simulation is used to investigate the response of velocity and turbulence in submerged wall jets to abrupt changes from smooth to rough beds. The submerged wall jets were experimentally investigated by Dey and Sarkar [JFM, 556, 337, 2006] at the Reynolds number of 17500 the Froude number of 4.09 and the submergence ratio of 1.12 on different rough beds that were generated by uniform sediments of different median diameters The SAS is carried out by means of a second-order-accurate finite volume method in space and time and the effect of bottom roughness is treated by the approach of Cebeci (2004). The evolution of free surface is captured by employing the two-phase volume of fluid (VOF) technique. The numerical results obtained by the SAS approach, incorporated with the VOF and the rough wall treatment, are in good agreement with the experimental measurements. The computed turbulent boundary layer grows more quickly and the depression of the free surface is more increased on the rough wall than those on smooth wall. The size of the fully developed zone shrinks and the decay rate of maximum streamwise velocity and Reynolds stress components are faster with increase in the wall roughness. Supported by NSF and NRF of Korea.

  6. An experimental study of near wall flow parameters in the blade end-wall corner region

    NASA Technical Reports Server (NTRS)

    Bhargava, Rakesh K.; Raj, Rishi S.

    1989-01-01

    The near wall flow parameters in the blade end-wall corner region is investigated. The blade end-wall corner region was simulated by mounting an airfoil section (NACA 65-015 base profile) symmetric blades on both sides of the flat plate with semi-circular leading edge. The initial 7 cm from the leading edge of the flat plate was roughened by gluing No. 4 floor sanding paper to artificially increase the boundary layer thickness on the flat plate. The initial flow conditions of the boundary layer upstream of the corner region are expected to dictate the behavior of flow inside the corner region. Therefore, an experimental investigation was extended to study the combined effect of initial roughness and increased level of free stream turbulence on the development of a 2-D turbulent boundary layer in the absence of the blade. The measurement techniques employed in the present investigation included, the conventional pitot and pitot-static probes, wall taps, the Preston tube, piezoresistive transducer and the normal sensor hot-wire probe. The pitot and pitot-static probes were used to obtain mean velocity profile measurements within the boundary layer. The measurements of mean surface static pressure were obtained with the surface static tube and the conventional wall tap method. The wall shear vector measurements were made with a specially constructed Preston tube. The flush mounted piezoresistive type pressure transducer were employed to measure the wall pressure fluctuation field. The velocity fluctuation measurements, used in obtaining the wall pressure-velocity correlation data, were made with normal single sensor hot-wire probe. At different streamwise stations, in the blade end-wall corner region, the mean values of surface static pressure varied more on the end-wall surface in the corner region were mainly caused by the changes in the curvature of the streamlines. The magnitude of the wall shear stress in the blade end-wall corner region increased significantly

  7. Flight Measurement of Wall-Pressure Fluctuations and Boundary-Layer Turbulence

    NASA Technical Reports Server (NTRS)

    Mull, Harold R.; Algranti, Joseph S.

    1960-01-01

    The results are presented for a flight test program using a fighter type jet aircraft flying at pressure altitudes of 10,000, 20,000, and 30,000 feet at Mach numbers from 0.3 to 0.8. Specially designed apparatus was used to measure and record the output of microphones and hot-wire anemometers mounted on the forward-fuselage section and wing of the airplane. Mean-velocity profiles in the boundary layers were obtained from total-pressure measurements. The ratio of the root-mean-square fluctuating wall pressure to the free-stream dynamic pressure is presented as a function of Reynolds number and Mach number. The longitudinal component of the turbulent-velocity fluctuations was measured, and the turbulence-intensity profiles are presented for the wing and forward-fuselage section. In general, the results are in agreement with wind-tunnel measurements which have been-reported in the literature. For example, the variation the square root of p(sup 2)/q times the square root of p(sup 2) is the root mean square of the wall-pressure fluctuation, and q is the free-stream dynamic pressure) with Reynolds number was found to be essentially constant for the forward-fuselage-section boundary layer, while variations at the wing station were probably unduly affected by the microphone diameter (5/8 in.), which was large compared with the boundary-layer thickness.

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

    PubMed Central

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

    2013-01-01

    Background Several previous epidemiologic studies have shown that high blood levels of carotenoids may be protective against early atherosclerosis, but results have been inconsistent. We assessed the association between atherosclerotic progression, measured by intima-media thickness of the common carotid artery wall, and serum levels of carotenoids. Methods We studied the effect of carotenoids on progression of early atherosclerosis in a population-based study. The association between concentrations of serum carotenoids, and intima-media thickness of the common carotid artery wall was explored in 840 middle-aged men (aged 46–65 years) from Eastern Finland. Ultrasonography of the common carotid arteries were performed at baseline and 7-year follow-up. Serum levels of carotenoids were analyzed at baseline. Changes in mean and maximum intima media thickness of carotid artery wall were related to baseline serum carotenoid levels in covariance analyses adjusted for covariates. Results In a covariance analysis with adjustment for age, ultrasound sonographer, maximum intima media thickness, examination year, body mass index, systolic blood pressure, smoking, physical activity, serum LDL cholesterol, family history of coronary heart disease, antihypertensive medication and serum high sensitivity C-reactive protein, 7-year change in maximum intima media thickness was inversely associated with lycopene (p = 0.005), α-carotene (p = 0.002) and β-carotene (p = 0.019), respectively. Conclusions The present study shows that high serum concentrations of carotenoids may be protective against early atherosclerosis. PMID:23700460

  9. Elevated Cell Wall Serine in Pleiotropic Staphylococcal Mutants

    PubMed Central

    Korman, Ruth Z.

    1966-01-01

    Korman, Ruth Z. (Cornell University, Ithaca, N.Y.). Elevated cell wall serine in pleiotropic staphylococcal mutants. J. Bacteriol. 92:762–768. 1966.—Physically purified cell walls were prepared from two staphylococcal strains and from pleiotropic variants derived from them. The quantitative amino acid and amino sugar content of these walls is reported. The pleiotypes, which are identified culturally by their failure to elaborate coagulase, their resistance to bacteriophage, and their sensitivity to mannitol, have altered molar ratios of amino acids and amino sugars in their cell walls. In comparison with lysine content, the serine content of the mutant wall is elevated and the glycine content is reduced. The glucosamine content is reduced also. It is postulated that the pleiotropic mutants possess an altered cell wall biosynthetic pathway. Images PMID:5922547

  10. Regeneration of near-wall turbulence structures

    NASA Technical Reports Server (NTRS)

    Hamilton, James M.; Kim, John J.; Waleffe, Fabian A.

    1993-01-01

    An examination of the regeneration mechanisms of near-wall turbulence and an attempt to investigate the critical Reynolds number conjecture of Waleffe & Kim is presented. The basis is an extension of the 'minimal channel' approach of Jimenez and Moin which emphasizes the near-wall region and further reduces the complexity of the turbulent flow. Reduction of the flow Reynolds number to the minimum value which will allow turbulence to be sustained has the effect of reducing the ratio of the largest scales to the smallest scales or, equivalently, of causing the near-wall region to fill more of the area between the channel walls. In addition, since each wall may have an active near-wall region, half of the channel is always somewhat redundant. If a plane Couette flow is instead chosen as the base flow, this redundancy is eliminated: the mean shear of a plane Couette flow has a single sign, and at low Reynolds numbers, the two wall regions share a single set of structures. A minimal flow with these modifications possesses, by construction, the strongest constraints which allow sustained turbulence, producing a greatly simplified flow in which the regeneration process can be examined.

  11. Three-dimensional ultrasound measurements of carotid vessel wall and plaque thickness and their relationship with pulmonary abnormalities in ex-smokers without airflow limitation.

    PubMed

    Cheng, Jieyu; Pike, Damien; Chow, Tommy W S; Kirby, Miranda; Parraga, Grace; Chiu, Bernard

    2016-09-01

    The relationship between carotid disease and modestly abnormal airflow in ex-smokers without chronic obstructive pulmonary disease (COPD) is not well-understood. We generated 3D ultrasound measurements of carotid vessel-wall-plus-plaque thickness (VWT) and vessel wall volume (VWV) to quantify and evaluate such carotid ultrasound measurements in ex- and never-smokers without airflow limitation. These patients did not fulfill the diagnostic criteria for COPD. We also investigated the relationship of carotid atherosclerosis with pulmonary phenotypes of COPD. We evaluated 61 subjects without a clinical diagnosis of pulmonary or vascular diseases including 34 never-smokers (72 ± 6 year) and 27 ex-smokers (73 ± 9 year). We measured mean VWT ([Formula: see text]) and mean VWT specific to carotid regions-of-interest ([Formula: see text]) and evaluated potential differences between ex- and never-smokers. Carotid ultrasound and pulmonary disease measurement relationships were also evaluated using correlation coefficients (r) and multivariate regression analyses. Ex-smokers had a significantly greater [Formula: see text] (p = 0.003) and [Formula: see text] (p < 0.00001) than never-smokers, whereas a significant difference between the two groups was not detected by VWV (p = 1.0). There were significant correlations between the ventilation defect percent (VDP) measured by MRI with [Formula: see text] (r = 0.42, p = 0.001) and [Formula: see text] (r = 0.56, p = 0.00001). Multivariate regression models showed that VDP significantly predicted [Formula: see text] (β = 0.38, p = 0.004) and [Formula: see text] (β = 0.50, p = 0.00001). VWT-based measurements detected differences in vessel-wall-plus-plaque burden in ex- and never-smokers, which were not revealed using VWV. There were significant correlations between cardiovascular and pulmonary disease biomarkers in these ex-smokers who did not have a clinical diagnosis of

  12. The Flow Field Downstream of a Dynamic Low Aspect Ratio Circular Cylinder: A Parametric Study

    NASA Astrophysics Data System (ADS)

    Gildersleeve, Samantha; Dan, Clingman; Amitay, Michael

    2015-11-01

    Flow past a static, low aspect ratio cylinder (pin) has shown the formation of vortical structures, namely the horseshoe and arch-type vortex. These vortical structures may have substantial effects in controlling flow separation over airfoils. In the present experiments, the flow field associated with a low aspect ratio cylinder as it interacts with a laminar boundary layer under static and dynamic conditions was investigated through a parametric study over a flat plate. As a result of the pin being actuated in the wall-normal direction, the structures formed in the wake of the pin were seen to be a strong function of actuation amplitude, driving frequency, and aspect ratio of the cylinder. The study was conducted at a Reynolds number of 1875, based on the local boundary layer thickness, with a free stream velocity of 10 m/s. SPIV data were collected for two aspect ratios of 0.75 and 1.125, actuation amplitudes of 6.7% and 16.7%, and driving frequencies of 175 Hz and 350 Hz. Results indicate that the presence and interactions between vortical structures are altered in comparison to the static case and suggest increased large-scale mixing when the pin is driven at the shedding frequency (350 Hz). Supported by the Boeing Company.

  13. Novel sonographic clues for diagnosis of antral gastritis and Helicobacter pylori infection: a clinical study.

    PubMed

    Cakmakci, Emin; Ucan, Berna; Colak, Bayram; Cinar, Hasibe Gokçe

    2014-09-01

    The purpose of this study was to find out whether transabdominal sonography may have a predictive role for detection of antral gastritis and Helicobacter pylori infection in the antrum. A total of 108 patients and 54 control participants were allocated into 3 groups: group 1, controls without any symptoms or findings of antral gastritis and H pylori infection; group 2, patients with symptoms and endoscopic findings consistent with gastritis in the absence of documented H pylori infection; and group 3, patients with symptoms and endoscopic findings consistent with gastritis and documented H pylori infection. These groups were compared in terms of demographics, antral wall thickness, mucosal layer (together with muscularis mucosa) thickness, and mucosal layer-to-antral wall thickness ratio. The groups had no statistically significant differences with respect to age, sex, body mass index, and smoking habits. However, it turned out that both antral walls and muscularis mucosa layers were thicker and the mucosal layer-to-antral wall thickness ratio was higher in groups 2 and 3 compared to group 1 (P > .001). In addition, group 3 had statistically significantly thicker antral walls and muscularis mucosa layers and a significantly increased mucosal layer-to-antral wall thickness ratio than group 2 (P < .001). Our results suggest that antral gastritis caused by H pylori infection is associated with characteristic features such as thickening of antral walls and mucosal layers on sonography. These novel clues may be useful in the diagnosis of gastritis, and unnecessary interventions and measures can be avoided in some cases. © 2014 by the American Institute of Ultrasound in Medicine.

  14. Progress Towards an LES Wall Model Including Unresolved Roughness

    NASA Astrophysics Data System (ADS)

    Craft, Kyle; Redman, Andrew; Aikens, Kurt

    2015-11-01

    Wall models used in large eddy simulations (LES) are often based on theories for hydraulically smooth walls. While this is reasonable for many applications, there are also many where the impact of surface roughness is important. A previously developed wall model has been used primarily for jet engine aeroacoustics. However, jet simulations have not accurately captured thick initial shear layers found in some experimental data. This may partly be due to nozzle wall roughness used in the experiments to promote turbulent boundary layers. As a result, the wall model is extended to include the effects of unresolved wall roughness through appropriate alterations to the log-law. The methodology is tested for incompressible flat plate boundary layers with different surface roughness. Correct trends are noted for the impact of surface roughness on the velocity profile. However, velocity deficit profiles and the Reynolds stresses do not collapse as well as expected. Possible reasons for the discrepancies as well as future work will be presented. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1053575. Computational resources on TACC Stampede were provided under XSEDE allocation ENG150001.

  15. Regulation of Neurospora crassa cell wall remodeling via the cot-1 pathway is mediated by gul-1.

    PubMed

    Herold, Inbal; Yarden, Oded

    2017-02-01

    Impairment of the Neurospora crassa Nuclear DBF2-related kinase-encoding gene cot-1 results in pleiotropic effects, including abnormally thick hyphal cell walls and septa. An increase in the transcript abundance of genes encoding chitin and glucan synthases and the chitinase gh18-5, but not the cell wall integrity pathway transcription factor rlm-1, accompany the phenotypic changes observed. Deletion of chs-5 or chs-7 in a cot-1 background results in a reduction of hyperbranching frequency characteristic of the cot-1 parent. gul-1 (a homologue of the yeast SSD1 gene) encodes a translational regulator and has been shown to partially suppress cot-1. We demonstrate that the high expression levels of the cell wall remodeling genes analyzed is curbed, and reaches near wild type levels, when gul-1 is inactivated. This is accompanied by morphological changes that include reduced cell wall thickness and restoration of normal chitin levels. We conclude that gul-1 is a mediator of cell wall remodeling within the cot-1 pathway.

  16. Retrieval of the thickness of undeformed sea ice from C-band compact polarimetric SAR images

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Dierking, W.; Zhang, J.; Meng, J. M.; Lang, H. T.

    2015-10-01

    In this paper we introduce a parameter for the retrieval of the thickness of undeformed first-year sea ice that is specifically adapted to compact polarimetric SAR images. The parameter is denoted as "CP-Ratio". In model simulations we investigated the sensitivity of CP-Ratio to the dielectric constant, thickness, surface roughness, and incidence angle. From the results of the simulations we deduced optimal conditions for the thickness retrieval. On the basis of C-band CTLR SAR data, which were generated from Radarsat-2 quad-polarization images acquired jointly with helicopter-borne sea ice thickness measurements in the region of the Sea of Labrador, we tested empirical equations for thickness retrieval. An exponential fit between CP-Ratio and ice thickness provides the most reliable results. Based on a validation using other compact polarimetric SAR images from the same region we found a root mean square (rms) error of 8 cm and a maximum correlation coefficient of 0.92 for the retrieval procedure when applying it on level ice of 0.9 m mean thickness.

  17. Likelihood Ratios for Glaucoma Diagnosis Using Spectral Domain Optical Coherence Tomography

    PubMed Central

    Lisboa, Renato; Mansouri, Kaweh; Zangwill, Linda M.; Weinreb, Robert N.; Medeiros, Felipe A.

    2014-01-01

    Purpose To present a methodology for calculating likelihood ratios for glaucoma diagnosis for continuous retinal nerve fiber layer (RNFL) thickness measurements from spectral domain optical coherence tomography (spectral-domain OCT). Design Observational cohort study. Methods 262 eyes of 187 patients with glaucoma and 190 eyes of 100 control subjects were included in the study. Subjects were recruited from the Diagnostic Innovations Glaucoma Study. Eyes with preperimetric and perimetric glaucomatous damage were included in the glaucoma group. The control group was composed of healthy eyes with normal visual fields from subjects recruited from the general population. All eyes underwent RNFL imaging with Spectralis spectral-domain OCT. Likelihood ratios for glaucoma diagnosis were estimated for specific global RNFL thickness measurements using a methodology based on estimating the tangents to the Receiver Operating Characteristic (ROC) curve. Results Likelihood ratios could be determined for continuous values of average RNFL thickness. Average RNFL thickness values lower than 86μm were associated with positive LRs, i.e., LRs greater than 1; whereas RNFL thickness values higher than 86μm were associated with negative LRs, i.e., LRs smaller than 1. A modified Fagan nomogram was provided to assist calculation of post-test probability of disease from the calculated likelihood ratios and pretest probability of disease. Conclusion The methodology allowed calculation of likelihood ratios for specific RNFL thickness values. By avoiding arbitrary categorization of test results, it potentially allows for an improved integration of test results into diagnostic clinical decision-making. PMID:23972303

  18. Magnetic domain wall engineering in a nanoscale permalloy junction

    NASA Astrophysics Data System (ADS)

    Wang, Junlin; Zhang, Xichao; Lu, Xianyang; Zhang, Jason; Yan, Yu; Ling, Hua; Wu, Jing; Zhou, Yan; Xu, Yongbing

    2017-08-01

    Nanoscale magnetic junctions provide a useful approach to act as building blocks for magnetoresistive random access memories (MRAM), where one of the key issues is to control the magnetic domain configuration. Here, we study the domain structure and the magnetic switching in the Permalloy (Fe20Ni80) nanoscale magnetic junctions with different thicknesses by using micromagnetic simulations. It is found that both the 90-° and 45-° domain walls can be formed between the junctions and the wire arms depending on the thickness of the device. The magnetic switching fields show distinct thickness dependencies with a broad peak varying from 7 nm to 22 nm depending on the junction sizes, and the large magnetic switching fields favor the stability of the MRAM operation.

  19. Towards a Viscous Wall Model for Immersed Boundary Methods

    NASA Technical Reports Server (NTRS)

    Brehm, Christoph; Barad, Michael F.; Kiris, Cetin C.

    2016-01-01

    Immersed boundary methods are frequently employed for simulating flows at low Reynolds numbers or for applications where viscous boundary layer effects can be neglected. The primary shortcoming of Cartesian mesh immersed boundary methods is the inability of efficiently resolving thin turbulent boundary layers in high-Reynolds number flow application. The inefficiency of resolving the thin boundary is associated with the use of constant aspect ratio Cartesian grid cells. Conventional CFD approaches can efficiently resolve the large wall normal gradients by utilizing large aspect ratio cells near the wall. This paper presents different approaches for immersed boundary methods to account for the viscous boundary layer interaction with the flow-field away from the walls. Different wall modeling approaches proposed in previous research studies are addressed and compared to a new integral boundary layer based approach. In contrast to common wall-modeling approaches that usually only utilize local flow information, the integral boundary layer based approach keeps the streamwise history of the boundary layer. This allows the method to remain effective at much larger y+ values than local wall modeling approaches. After a theoretical discussion of the different approaches, the method is applied to increasingly more challenging flow fields including fully attached, separated, and shock-induced separated (laminar and turbulent) flows.

  20. Integrating shotcrete walls into the natural landscape by application of 'Green Walls'

    NASA Astrophysics Data System (ADS)

    Medl, Alexandra; Kikuta, Silvia

    2017-04-01

    Steep slopes resulting from major road infrastructure constructions are increasingly perceived as disagreeable disturbance in the landscape. Thus, a tool to consider landscape aspects and integrate these slopes into the natural environment is required. The challenge is to establish a sustainable vegetation layer despite of adverse circumstances such as inclinations of almost 90⁰, exposed position of slopes near streets and lack of soil and water supply. The objective of this study was to assess the performance of an innovative greening technology for vertical structures (shotcrete wall) in terms of vegetation development on varying plant substrates and geotextiles. The field experiment in Steinach am Brenner, Tyrol, Austria, included testing three plant substrates on basis of nearby rocky excavation material ('Innsbrucker Quarzphyllit', 'Bündnerschiefer' and 'Zentralgneis') combined with compost. Additionally, five geotextiles (geogrid (3x4 mm), geogrid (9x10 mm), coir net, coir mat, geo mat) were applied for evaluation. All test combinations were evaluated regarding vegetation cover and biomass production from 2015 to 2016. Analyses of chemical properties were conducted for all plant substrates. Results showed highest vegetation cover ratio on 'Bündnerschiefer' and 'Innsbrucker Quarzphyllit', which can be explained by the favorable mineral composition (nutrient storage capacity) and chemical properties of compost (lower values of electrical conductivity and C/N ratio). In conclusion, the use of 'Green Walls' filled with 'Bündnerschiefer' or 'Innsbrucker Quarzphyllit' plant substrate in combination with netlike geotextiles proved best, since geo grid and coir net turned out as most successful one year after installation. 'Green Walls' are promising in terms of establishing an optimal vegetation cover on vertical structures and are well suited for integrating shotcrete walls into the landscape. The use of local excavation material for greening purposes can be

  1. New Crustal Thickness for Djibouti, Afar, Using Seismic Techniques

    NASA Astrophysics Data System (ADS)

    Dugda, Mulugeta; Bililign, Solomon

    2008-10-01

    Crustal thickness and Poisson's ratio for the seismic station ATD in Djibouti, Afar, has been investigated using two seismic techniques (H-κ stacking of receiver functions and a joint inversion of receiver functions and surface wave group velocities). Both techniques give consistent results of crustal thickness 23±1.5 km and Poisson's ratio 0.31±0.02. We also determined a mean P-wave velocity (Vp) of ˜6.2 km/s but ˜6.9-7.0 km/s below a 2 - 5 km thick low velocity layer at the surface. Previous studies of crustal structure for Djibouti reported that the crust is 6 to 11 km thick while our study shows that the crust beneath Djibouti is between 20 and 25 km. This study argues that the crustal thickness values reported for Djibouti for the last 3 decades were not consistent with the reports for the other neighboring region in central and eastern Afar. Our results for ATD in Djibouti, however, are consistent with the reports of crustal thickness in many other parts of central and eastern Afar. We attribute this difference to how the Moho (the crust-mantle discontinuity) is defined (an increase of Vp to 7.4 km/s in this study vs. 6.9 km/s in previous studies).

  2. Detonation Failure Thickness Measurement in AN Annular Geometry

    NASA Astrophysics Data System (ADS)

    Mack, D. B.; Petel, O. E.; Higgins, A. J.

    2007-12-01

    The failure thickness of neat nitromethane in aluminum confinement was measured using a novel experimental technique. The thickness was approximated in an annular geometry by the gap between a concentric aluminum tube and rod. This technique was motivated by the desire to have a periodic boundary condition in the direction orthogonal to the annulus thickness, rather than a free surface occurring in typical rectangular geometry experiments. This results in a two-dimensional charge analogous to previous failure thickness setups but with infinite effective width (i.e. infinite aspect ratio). Detonation propagation or failure was determined by the observation of failure patterns engraved on the aluminum rod by the passing detonation. Analysis of these engraved patterns provides a statistical measurement of the spatial density of failure waves. Failure was observed as far as 180 thicknesses downstream. The failure thickness was measured to be 1.45 mm±0.15 mm.

  3. Partial Insulation of Aerated Concrete Wall in its Thermal Bridge Regions

    NASA Astrophysics Data System (ADS)

    Li, Baochang; Guo, Lirong; Li, Yubao; Zhang, Tiantian; Tan, Yufei

    2018-01-01

    As a self-insulating building material which can meet the 65 percent energy-efficiency requirements in cold region of China, aerated concrete blocks often go moldy, frost heaving, or cause plaster layer hollowing at thermal bridge parts in the extremely cold regions due to the restrictions of environmental climate and construction technique. In this paper, partial insulation measures of the thermal-bridge position of these parts of aerated concrete walls are designed to weaken or even eliminate thermal bridge effect and improve the temperature of thermal-bridge position. A heat transfer calculation model for L-shaped wall and T-shaped wall is developed. Based on the simulation result, the influence of the thickness on the temperature field is analyzed. Consequently, the condensation inside self-thermal-insulating wall and frost heaving caused by condensation and low temperature will be reduced, avoiding damage to the wall body from condensation..

  4. Positive ion temperature effect on the plasma-wall transition

    NASA Astrophysics Data System (ADS)

    Morales Crespo, R.

    2018-06-01

    This paper analyses the plasma-wall interaction of a plasma in contact with a conducting planar surface when the positive-ion temperature is not negligible compared with the electron one. The electric potential from the plasma to the wall is obtained by the appropriate formulation of the model as an initial-value problem as well as some features useful for experimental applications, such as the positive current-to-voltage characteristics, the saturation current density, the floating potential or an estimation of the sheath thickness. Finally, it is analysed how all these quantities depend on the ionization degree and the positive-ion temperature.

  5. Method of non-destructively inspecting a curved wall portion

    DOEpatents

    Fong, James T.

    1996-01-01

    A method of non-destructively inspecting a curved wall portion of a large and thick walled vessel for a defect by computed tomography is provided. A collimated source of radiation is placed adjacent one side of the wall portion and an array of detectors for the radiation is placed on the other side adjacent the source. The radiation from the source passing through the wall portion is then detected with the detectors over a limited angle, dependent upon the curvature of the wall of the vessel, to obtain a dataset. The source and array are then coordinately moved relative to the wall portion in steps and a further dataset is obtained at each step. The plurality of datasets obtained over the limited angle is then processed to produce a tomogram of the wall portion to determine the presence of a defect therein. In a preferred embodiment, the curved wall portion has a center of curvature so that the source and the array are positioned at each step along a respective arc curved about the center. If desired, the detector array and source can be reoriented relative to a new wall portion and an inspection of the new wall portion can be easily obtained. Further, the source and detector array can be indexed in a direction perpendicular to a plane including the limited angle in a plurality of steps so that by repeating the detecting and moving steps at each index step, a three dimensional image can be created of the wall portion.

  6. The effect of thickness on fatigue crack propagation in 7475-T731 aluminum alloy sheet

    NASA Technical Reports Server (NTRS)

    Daiuto, R. A.; Hillberry, B. M.

    1984-01-01

    Tests were conducted on three thicknesses of 7475-T731 aluminum alloy sheet to investigate the effect of thickness on fatigue crack propagation under constant amplitude loading conditions and on retardation following a single peak overload. Constant amplitude loading tests were performed at stress ratios of 0.05 and 0.75 to obtain data for conditions with crack closure and without crack closure, respectively. At both stress ratios a thickness effect was clearly evident, with thicker specimens exhibiting higher growth rates in the transition from plane strain to plane stress region. The effect of thickness for a stress ratio of 0.05 corresponded well with the fracturing mode transitions observed on the specimens. A model based on the strain energy release rate which accounted for the fracture mode transition was found to correlate the thickness effects well. The specimens tested at the stress ratio of 0.75 did not make the transition from tensile mode to shear mode, indicating that another mechanism besides crack closure or fracture mode transition was active.

  7. Optical transmission of nematic liquid crystal 5CB doped by single-walled and multi-walled carbon nanotubes.

    PubMed

    Lisetski, L N; Fedoryako, A P; Samoilov, A N; Minenko, S S; Soskin, M S; Lebovka, N I

    2014-08-01

    Comparative studies of optical transmission of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs), dispersed in nematic liquid crystal matrix 5CB, were carried out. The data evidence violations of Beer-Lambert-Bouguer (BLB) law both in cell thickness and concentration dependencies. The most striking is the fact that optical transmission dependencies for SWCNTs and MWCNTs were quite different in the nematic phase, but they were practically indistinguishable in the isotropic phase. Monte Carlo simulations of the impact of aggregation on direct transmission and violation of BLB law were also done. The results were discussed accounting for the tortuous shape of CNTs, their physical properties and aggregation, as well as strong impact of perturbations of the nematic 5CB structure inside coils and in the vicinity of CNT aggregates.

  8. Optimal slice thickness for cone-beam CT with on-board imager

    PubMed Central

    Seet, KYT; Barghi, A; Yartsev, S; Van Dyk, J

    2010-01-01

    Purpose: To find the optimal slice thickness (Δτ) setting for patient registration with kilovoltage cone-beam CT (kVCBCT) on the Varian On Board Imager (OBI) system by investigating the relationship of slice thickness to automatic registration accuracy and contrast-to-noise ratio. Materials and method: Automatic registration was performed on kVCBCT studies of the head and pelvis of a RANDO anthropomorphic phantom. Images were reconstructed with 1.0 ≤ Δτ (mm) ≤ 5.0 at 1.0 mm increments. The phantoms were offset by a known amount, and the suggested shifts were compared to the known shifts by calculating the residual error. A uniform cylindrical phantom with cylindrical inserts of various known CT numbers was scanned with kVCBCT at 1.0 ≤ Δτ (mm) ≤ 5.0 at increments of 0.5 mm. The contrast-to-noise ratios for the inserts were measured at each Δτ. Results: For the planning CT slice thickness used in this study, there was no significant difference in residual error below a threshold equal to the planning CT slice thickness. For Δτ > 3.0 mm, residual error increased for both the head and pelvis phantom studies. The contrast-to-noise ratio is proportional to slice thickness until Δτ = 2.5 mm. Beyond this point, the contrast-to-noise ratio was not affected by Δτ. Conclusion: Automatic registration accuracy is greatest when 1.0 ≤ Δτ (mm) ≤ 3.0 is used. Contrast-to-noise ratio is optimal for the 2.5 ≤ Δτ (mm) ≤ 5.0 range. Therefore 2.5 ≤ Δτ (mm) ≤ 3.0 is recommended for kVCBCT patient registration where the planning CT is 3.0 mm. PMID:21611047

  9. Significance of Shear Wall in Multi-Storey Structure With Seismic Analysis

    NASA Astrophysics Data System (ADS)

    Bongilwar, Rajat; Harne, V. R.; Chopade, Aditya

    2018-03-01

    In past decades, shear walls are one of the most appropriate and important structural component in multi-storied building. Therefore, it would be very interesting to study the structural response and their systems in multi-storied structure. Shear walls contribute the stiffness and strength during earthquakes which are often neglected during design of structure and construction. This study shows the effect of shear walls which significantly affect the vulnerability of structures. In order to test this hypothesis, G+8 storey building was considered with and without shear walls and analyzed for various parameters like base shear, storey drift ratio, lateral displacement, bending moment and shear force. Significance of shear wall has been studied with the help of two models. First model is without shear wall i.e. bare frame and other another model is with shear wall considering opening also in it. For modeling and analysis of both the models, FEM based software ETABS 2016 were used. The analysis of all models was done using Equivalent static method. The comparison of results has been done based on same parameters like base shear, storey drift ratio, lateral displacement, bending moment and shear force.

  10. Textural domain walls in superfluid 3He-B

    NASA Astrophysics Data System (ADS)

    Mizushima, Takeshi

    Owing to the richness of symmetry, the superfluid 3He serves as a rich repository of topological quantum phenomena. This includes the emergence of surface Majorana fermions and their quantum mass acquisition at the topological critical point. Furthermore, the marriage of the prototype topological superfluid with nanofabrication techniques brings about a rich variety of spontaneous symmetry breaking, such as the formation of the stripe order and nontrivial domain walls. In this work, we examine the possible formation of textural domain walls in the superfluid 3He-B confined to a thin slab with a sub-micron thickness. When an applied magnetic field is much higher than the dipolar field, two nearly degenerate ground states appear, which are characterized by the Ising order associated with the spontaneous breaking of a magnetic order-two symmetry, lcirc;z = + 1 and - 1 . We here discuss the structure of the textural domain wall formed by the spatial modulation of the Ising order, such as low-lying quasiparticle excitations and spontaneous spin current. We also report bosonic modes bound to the textural domain wall.

  11. A benchmark study for the crown-type splashing dynamics of one- and two-component droplet wall-film interactions

    NASA Astrophysics Data System (ADS)

    Geppert, A.; Terzis, A.; Lamanna, G.; Marengo, M.; Weigand, B.

    2017-12-01

    The present paper investigates experimentally the impact dynamics of crown-type splashing for miscible two- and one-component droplet wall-film interactions over a range of Weber numbers and dimensionless film thicknesses. The splashing outcome is parametrised in terms of a set of quantifiable parameters, such as crown height, top and base diameter, wall inclination, number of fingers, and secondary droplet properties. The results show that the outcome of a splashing event is not affected by the choice of similar or dissimilar fluids, provided the dimensionless film thickness is larger than 0.1. Below this threshold, distinctive features of two-component interactions appear, such as hole formation and crown bottom breakdown. The observation of different crown shapes (e.g. V-shaped, cylindrical, and truncated-cone) confirms that vorticity production induces changes in the crown wall inclination, thus affecting the evolution of the crown height and top diameter. The evolution of the crown base diameter, instead, is mainly dependent on the relative importance of liquid inertia and viscous losses in the wall-film. The maximum number of liquid fingers decreases with increasing wall, film thickness, due to the enhanced attenuation of the effect of surface properties on the fingering process. The formation of secondary droplets is also affected by changes in the crown wall inclination. In particular, for truncated-cone shapes the occurrence of crown rim contraction induces a large scatter in the secondary droplet properties. Consequently, empirical models for the maximum number and mean diameter of the secondary droplets are derived for V-shaped crowns, as observed for the hexadecane-Hyspin interactions.

  12. Macular Choroidal Small-Vessel Layer, Sattler's Layer and Haller's Layer Thicknesses: The Beijing Eye Study.

    PubMed

    Zhao, Jing; Wang, Ya Xing; Zhang, Qi; Wei, Wen Bin; Xu, Liang; Jonas, Jost B

    2018-03-13

    To study macular choroidal layer thickness, 3187 study participants from the population-based Beijing Eye Study underwent spectral-domain optical coherence tomography with enhanced depth imaging for thickness measurements of the macular small-vessel layer, including the choriocapillaris, medium-sized choroidal vessel layer (Sattler's layer) and large choroidal vessel layer (Haller's layer). In multivariate analysis, greater thickness of all three choroidal layers was associated (all P < 0.05) with higher prevalence of age-related macular degeneration (AMD) (except for geographic atrophy), while it was not significantly (all P > 0.05) associated with the prevalence of open-angle glaucoma or diabetic retinopathy. There was a tendency (0.07 > P > 0.02) toward thinner choroidal layers in chronic angle-closure glaucoma. The ratio of small-vessel layer thickness to total choroidal thickness increased (P < 0.001; multivariate analysis) with older age and longer axial length, while the ratios of Sattler's layer and Haller's layer thickness to total choroidal thickness decreased. A higher ratio of small-vessel layer thickness to total choroidal thickness was significantly associated with a lower prevalence of AMD (early type, intermediate type, late geographic type). Axial elongation-associated and aging-associated choroidal thinning affected Haller's and Sattler's layers more markedly than the small-vessel layer. Non-exudative and exudative AMD, except for geographic atrophy, was associated with slightly increased choroidal thickness.

  13. Synthesis and electrochemical performance of multi-walled carbon nanotube/polyaniline/MnO 2 ternary coaxial nanostructures for supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Liu, Jianhua; Zou, Jianhua; Chunder, Anindarupa; Chen, Yiqing; Zhai, Lei

    Multi-walled carbon nanotube (MWCNT)/polyaniline (PANI)/MnO 2 (MPM) ternary coaxial structures are fabricated as supercapacitor electrodes via a simple wet chemical method. The electrostatic interaction between negative poly(4-styrenesulfonic acid) (PSS) molecules and positive Mn 2+ ions causes the generation of MnO 2 nanostructures on MWCNT surfaces while the introduction of PANI layers with appropriate thickness on MWCNT surfaces facilitates the formation of MWCNT/PANI/MnO 2 ternary coaxial structures. The thickness of PANI coatings is controlled by tuning the aniline/MWCNT ratio. The effect of PANI thickness on the subsequent MnO 2 nanoflakes attachment onto MWCNTs, and the MPM structures is investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and field-emission scanning electron microscopy (FESEM). The results suggest that appropriate thickness of PANI layers is important for building MPM ternary coaxial structures without the agglomeration of MnO 2 nanoflakes. The MPM ternary coaxial structures provide large interaction area between the MnO 2 nanoflakes and electrolyte, and improve the electrochemical utilization of the hydrous MnO 2, and decrease the contact resistance between MnO 2 and PANI layer coated MWCNTs, leading to intriguing electrochemical properties for the applications in supercapacitors such as a specific capacitance of 330 Fg -1 and good cycle stability.

  14. Diaphragmatic thickness ratio (inspiratory/expiratory) as a diagnostic method of diaphragmatic palsy associated with interescalene block.

    PubMed

    López Escárraga, V M; Dubos España, K; Castillo Bustos, R H; Peidró, L; Sastre, S; Sala-Blanch, X

    2018-02-01

    Diaphragmatic paralysis is a side-effect associated with interscalene block. Thickness index of the diaphragm muscle (inspiratory thickness/expiratory thickness) obtained by ultrasound has recently been introduced in clinical practice for diagnosis of diaphragm muscle atrophy. Our objective was to evaluate this index for the diagnosis of acute phrenic paresis associated with interscalene block. We designed an observational study in 22 patients scheduled for shoulder arthroscopy. Spirometry was performed (criteria of phrenic paresis was a decrease in FVC and FEV1 ≥20%). Ultrasound apposition zone was assessed in anterior axillary line and diaphragmatic displacement was evaluated on inspiration and expiration (number of intercostal spaces; phrenic paresis considered a reduction ≥25%) and thickness of the diaphragm muscle (a phrenic paresis was considered an index <1.2). These determinations were performed before and at 20min after interscalene block at C5-C6 with 20ml of 0.5% ropivacaine. Twenty-one patients (95%) presented phrenic nerve block according to one or more of the methods used. One patient did not show any symptoms or signs suggestive of phrenic paralysis and was excluded. All the patients presented phrenic paresis based on the diaphragmatic thickness index, with the pre-block index being 1.8±0.5 and post-block of 1.05±0.06 (P<0.001). Ninety percent of the patients (19) presented phrenic paresis according to spirometry and all the patients had a reduction in diaphragmatic movement after the block (from 1.9±0.5 intercostal spaces to 0.5±0.3; P<0.001). The index of inspiratory / expiratory diaphragmatic thickness at cut-off <1.2 seems to be useful in the diagnosis of phrenic paresis associated with interscalene block. This index does not require a baseline pre-assessment. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

  15. Controlling effective aspect ratio and packing of clay with pH for improved gas barrier in nanobrick wall thin films.

    PubMed

    Hagen, David A; Saucier, Lauren; Grunlan, Jaime C

    2014-12-24

    Polymer-clay thin films constructed via layer-by-layer (LbL) assembly, with a nanobrick wall structure (i.e., clay nanoplatelets as bricks surrounded by a polyelectrolyte mortar), are known to exhibit a high oxygen barrier. Further barrier improvement can be achieved by lowering the pH of the clay suspension in the polyethylenimine (PEI) and montmorillonite (MMT) system. In this case, the charge of the deposited PEI layer is increased in the clay suspension environment, which causes more clay to be deposited. At pH 4, MMT platelets deposit with near perfect ordering, observed with transmission electron microscopy, enabling a 5× improvement in the gas barrier for a 10 PEI/MMT bilayer thin film (85 nm) relative to the same film made with pH 10 MMT. This improved gas barrier approaches that achieved with much higher aspect ratio vermiculite clay. In essence, lower pH is generating a higher effective aspect ratio for MMT due to greater induced surface charge in the PEI layers, which causes heavier clay deposition. These flexible, transparent nanocoatings have a wide range of possible applications, from food and electronics packaging to pressurized bladders.

  16. Single-Walled Carbon Nanotube Dominated Micron-Wide Stripe Patterned-Based Ferroelectric Field-Effect Transistors with HfO2 Defect Control Layer

    NASA Astrophysics Data System (ADS)

    Tan, Qiuhong; Wang, Qianjin; Liu, Yingkai; Yan, Hailong; Cai, Wude; Yang, Zhikun

    2018-04-01

    Ferroelectric field-effect transistors (FeFETs) with single-walled carbon nanotube (SWCNT) dominated micron-wide stripe patterned as channel, (Bi,Nd)4Ti3O12 films as insulator, and HfO2 films as defect control layer were developed and fabricated. The prepared SWCNT-FeFETs possess excellent properties such as large channel conductance, high on/off current ratio, high channel carrier mobility, great fatigue endurance performance, and data retention. Despite its thin capacitance equivalent thickness, the gate insulator with HfO2 defect control layer shows a low leakage current density of 3.1 × 10-9 A/cm2 at a gate voltage of - 3 V.

  17. Method and apparatus for constructing an underground barrier wall structure

    DOEpatents

    Dwyer, Brian P.; Stewart, Willis E.; Dwyer, Stephen F.

    2002-01-01

    A method and apparatus for constructing a underground barrier wall structure using a jet grout injector subassembly comprising a pair of primary nozzles and a plurality of secondary nozzles, the secondary nozzles having a smaller diameter than the primary nozzles, for injecting grout in directions other than the primary direction, which creates a barrier wall panel having a substantially uniform wall thickess. This invention addresses the problem of the weak "bow-tie" shape that is formed during conventional jet injection when using only a pair of primary nozzles. The improvement is accomplished by using at least four secondary nozzles, of smaller diameter, located on both sides of the primary nozzles. These additional secondary nozzles spray grout or permeable reactive materials in other directions optimized to fill in the thin regions of the bow-tie shape. The result is a panel with increased strength and substantially uniform wall thickness.

  18. Imaging the inside of thick structures using cosmic rays

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Guardincerri, E., E-mail: elenaguardincerri@lanl.gov; Durham, J. M.; Morris, C.

    2016-01-15

    The authors present here a new method to image reinforcement elements inside thick structures and the results of a demonstration measurement performed on a mock-up wall built at Los Alamos National Laboratory. The method, referred to as “multiple scattering muon radiography”, relies on the use of cosmic-ray muons as probes. The work described in this article was performed to prove the viability of the technique as a means to image the interior of the dome of Florence Cathedral Santa Maria del Fiore, one of the UNESCO World Heritage sites and among the highest profile buildings in existence. Its result showsmore » the effectiveness of the technique as a tool to radiograph thick structures and image denser object inside them.« less

  19. Imaging the inside of thick structures using cosmic rays

    DOE PAGES

    Guardincerri, E.; Durham, J. M.; Morris, C.; ...

    2016-01-01

    Here, we present a new method to image reinforcement elements inside thick structures and the results of a demonstration measurement performed on a mock-up wall built at Los Alamos National Laboratory. The method, referred to as “multiple scattering muon radiography”, relies on the use of cosmic-ray muons as probes. Our work was performed to prove the viability of the technique as a means to image the interior of the dome of Florence Cathedral Santa Maria del Fiore, one of the UNESCO World Heritage sites and among the highest profile buildings in existence. This result shows the effectiveness of the techniquemore » as a tool to radiograph thick structures and image denser object inside them.« less

  20. Measure of chest wall thickness in French soldiers: which technique to use for needle decompression of tension pneumothorax at the front?

    PubMed

    Lamblin, Antoine; Turc, Jean; Bylicki, Olivier; Lohéas, Damien; Martinez, Jean-Yves; Derkenne, Clément; Wey, Pierre-François; Précloux, Pascal

    2014-07-01

    Needle decompression of tension pneumothorax in soldiers of the French infantry has a risk for failure when the standard procedure that involves the insertion of a 14-gauge, 5-cm catheter into the 2nd intercostal space (ICS) is used. This study measured the chest wall thickness (CWT) to assess whether this approach is appropriate. CWT was measured by ultrasound in 122 French soldiers at the 2nd and 4th ICSs on both the right and left sides. CWT was measured at 4.19 cm (± 0.96 cm) at the 2nd ICS and 3.00 cm (± 0.91 cm) at the 4th ICS (p < 0.001). CWT was greater than 5 cm in 24.2% of cases at the 2nd ICS and 4.9% of cases at the 4th ICS (p < 0.001). This study suggests a high risk of failure when using the technique currently taught in the French army. A lateral approach into the 4th ICS could decrease this risk. The results of this study must be validated in patients presenting tension pneumothorax. Reprint & Copyright © 2014 Association of Military Surgeons of the U.S.

  1. Process simulations for manufacturing of thick composites

    NASA Astrophysics Data System (ADS)

    Kempner, Evan A.

    The availability of manufacturing simulations for composites can significantly reduce the costs associated with process development. Simulations provide a tool for evaluating the effect of processing conditions on the quality of parts produced without requiring numerous experiments. This is especially significant in parts that have troublesome features such as large thickness. The development of simulations for thick walled composites has been approached by examining the mechanics of resin flow and fiber deformation during processing, applying these evaluations to develop simulations, and evaluating the simulation with experimental results. A unified analysis is developed to describe the three-dimensional resin flow and fiber preform deformation during processing regardless of the manufacturing process used. It is shown how the generic governing evaluations in the unified analysis can be applied to autoclave molding, compression molding, pultrusion, filament winding, and resin transfer molding. A comparison is provided with earlier models derived individually for these processes. The evaluations described for autoclave curing were used to produce a one-dimensional cure simulation for autoclave curing of thick composites. The simulation consists of an analysis for heat transfer and resin flow in the composite as well as bleeder plies used to absorb resin removed from the part. Experiments were performed in a hot press to approximate curing in an autoclave. Graphite/epoxy laminates of 3 cm and 5 cm thickness were cured while monitoring temperatures at several points inside the laminate and thickness. The simulation predicted temperatures fairly closely, but difficulties were encountered in correlation of thickness results. This simulation was also used to study the effects of prepreg aging on processing of thick composites. An investigation was also performed on filament winding with prepreg tow. Cylinders were wound of approximately 12 mm thickness with pressure

  2. Axisymmetric wave propagation in buried, fluid-filled pipes: effects of wall discontinuities

    NASA Astrophysics Data System (ADS)

    Muggleton, J. M.; Brennan, M. J.

    2005-03-01

    Water leakage from buried pipes is a subject of great concern in Britain and across the world because of decreasing water supplies due to changing rainfall patterns, deterioration of antiquated distribution systems, and an increasing population. Correlation techniques are widely used to locate the leaks, however, difficulties are encountered when repairs have been made to a pipe by inserting a new length of pipe to replace a damaged section. Although this practice is now discouraged, the new sections might be of a different material or possibly different cross-section or wall thickness. The wave propagation behaviour at such joints is poorly understood at present. In earlier work, simple expressions for the wavenumbers of the s=1 (fluid-dominated) and s=2 (shell dominated) axisymmetric wave types were derived for a fluid-filled elastic pipe, both in vacuo and surrounded by an elastic medium of infinite extent. In this paper, the wave transmission and reflection characteristics of these waves at an axisymmetric pipe wall discontinuity in a fluid-filled piping system are investigated theoretically. For changes in wall thickness or wall elasticity, simple expressions may be used to characterise the joint. The reason for this is that negligible energy conversion between the wavetypes occurs, so the wavetypes can be considered separately. For changes in the fluid cross-section, significant mode conversion occurs and the wavetypes must be considered together.

  3. Effect of contrast enhancement on measurement of carotid artery intimal medial thickness.

    PubMed

    Macioch, James E; Katsamakis, C Dean; Robin, Jason; Liebson, Philip R; Meyer, Peter M; Geohas, Chris; Raichlen, Joel S; Davidson, Michael H; Feinstein, Steven B

    2004-02-01

    Previous studies have used standard B-mode ultrasound to quantify the aggregate mean intimal medial thickness (IMT) of the near and far wall of the common carotid artery (CCA). Many investigators have had difficulty in accurately evaluating the near wall IMT secondary to difficulty in discerning the vessel lumen and intima. The purpose of this study is to determine the effect of contrast enhanced ultrasound on IMT measurement when compared with non-enhanced images. Twenty-six patients who had standard carotid ultrasounds completed over a 6-month period were evaluated, with 24 imaged by the same sonographer. Five to six measurements of the near and far walls were obtained over a 1 cm distance, beginning and ending 0.5 cm and 1.5 cm proximal to the carotid bifurcation. The measurements were made with and without the contrast agent Optison (perflutren protein type-A microspheres), which was given as an i.v. bolus (0.5-0.7 cc). Of those imaged by the same sonographer, 40 carotid arteries were examined and a total of 867 measurements were obtained. A total of 10% of the carotid ultrasounds were restudied approximately 1 month after the initial interpretation to assess observer accuracy. The near wall CCA mean (SD) IMT was 0.075 (0.019) cm for left with contrast versus 0.067 (0.023) cm for left without contrast and 0.089 (0.024) cm for right with versus 0.071 (0.022) cm for right without, p < or = 0.0001 both sides. For the far wall of the CCA, the mean (SD) IMT comparison was 0.075 (0.021) cm for left with versus 0.070 (0.016) cm for left without, p = 0.005, and 0.070 (0.023) cm for right with versus 0.070 (0.016) cm for right without, p = 0.68. In conclusion, contrast-enhanced IMT measurement showed a highly statistically significant difference in near carotid wall thickness determinations versus non-contrast values. The thicker measurement is in agreement with previously reported data showing that non-contrast images underestimated near wall common carotid IMT in

  4. Fluid Structural Analysis of Human Cerebral Aneurysm Using Their Own Wall Mechanical Properties

    PubMed Central

    Valencia, Alvaro; Burdiles, Patricio; Ignat, Miguel; Mura, Jorge; Rivera, Rodrigo; Sordo, Juan

    2013-01-01

    Computational Structural Dynamics (CSD) simulations, Computational Fluid Dynamics (CFD) simulation, and Fluid Structure Interaction (FSI) simulations were carried out in an anatomically realistic model of a saccular cerebral aneurysm with the objective of quantifying the effects of type of simulation on principal fluid and solid mechanics results. Eight CSD simulations, one CFD simulation, and four FSI simulations were made. The results allowed the study of the influence of the type of material elements in the solid, the aneurism's wall thickness, and the type of simulation on the modeling of a human cerebral aneurysm. The simulations use their own wall mechanical properties of the aneurysm. The more complex simulation was the FSI simulation completely coupled with hyperelastic Mooney-Rivlin material, normal internal pressure, and normal variable thickness. The FSI simulation coupled in one direction using hyperelastic Mooney-Rivlin material, normal internal pressure, and normal variable thickness is the one that presents the most similar results with respect to the more complex FSI simulation, requiring one-fourth of the calculation time. PMID:24151523

  5. The Relationship Between Surface Curvature and Abdominal Aortic Aneurysm Wall Stress.

    PubMed

    de Galarreta, Sergio Ruiz; Cazón, Aitor; Antón, Raúl; Finol, Ender A

    2017-08-01

    The maximum diameter (MD) criterion is the most important factor when predicting risk of rupture of abdominal aortic aneurysms (AAAs). An elevated wall stress has also been linked to a high risk of aneurysm rupture, yet is an uncommon clinical practice to compute AAA wall stress. The purpose of this study is to assess whether other characteristics of the AAA geometry are statistically correlated with wall stress. Using in-house segmentation and meshing algorithms, 30 patient-specific AAA models were generated for finite element analysis (FEA). These models were subsequently used to estimate wall stress and maximum diameter and to evaluate the spatial distributions of wall thickness, cross-sectional diameter, mean curvature, and Gaussian curvature. Data analysis consisted of statistical correlations of the aforementioned geometry metrics with wall stress for the 30 AAA inner and outer wall surfaces. In addition, a linear regression analysis was performed with all the AAA wall surfaces to quantify the relationship of the geometric indices with wall stress. These analyses indicated that while all the geometry metrics have statistically significant correlations with wall stress, the local mean curvature (LMC) exhibits the highest average Pearson's correlation coefficient for both inner and outer wall surfaces. The linear regression analysis revealed coefficients of determination for the outer and inner wall surfaces of 0.712 and 0.516, respectively, with LMC having the largest effect on the linear regression equation with wall stress. This work underscores the importance of evaluating AAA mean wall curvature as a potential surrogate for wall stress.

  6. Effect of Various Interface Thicknesses on the Behaviour of Infilled frame Subjected to Lateral Load

    NASA Astrophysics Data System (ADS)

    Senthil, K.; Muthukumar, S.; Rupali, S.; Satyanarayanan, K. S.

    2018-03-01

    Two dimensional numerical investigations were carried out to study the influence of interface thickness on the behaviour of reinforced concrete frames subjected to in-plane lateral loads using commercial finite element tool SAP 2000. The cement mortar, cork and foam was used as interface material and their effect was studied by varying thicknesses as 6, 8, 10, 14 and 20 mm. The effect of lateral loads on infill masonry wall was also studied by varying arbitrary loads as 10, 20, 40 and 60 kN. The resistance of the frame with cement mortar was found maximum with the interface thickness 10 mm therefore, it is concluded that the maximum influence of interface thickness of 10 mm was found effective. The resistance of integral infill frame with cork and foam interface was found maximum with the interface thickness 6 mm and it is concluded that 6 mm thick interface among the chosen thickness was found effective.

  7. Single-Walled Carbon Nanotube Film Supported Nanofiltration Membrane with a Nearly 10 nm Thick Polyamide Selective Layer for High-Flux and High-Rejection Desalination.

    PubMed

    Zhu, Yuzhang; Xie, Wei; Gao, Shoujian; Zhang, Feng; Zhang, Wenbin; Liu, Zhaoyang; Jin, Jian

    2016-09-01

    Fabricating nanofiltration (NF) membranes with high permeating flux and simultaneous high rejection rate for desalination is rather significant and highly desired. A new avenue is reported in this work to design NF membrane by using polydopamine wrapped single-walled carbon nanotube (PD/SWCNTs) ultrathin film as support layer instead of the use of traditional polymer-based underlying layers. Thanks to the high porosity, smooth surface, and more importantly optimal hydrophilic surface of PD/SWCNTs film, a defect-free polyamide selective layer for NF membrane with thickness of as thin as 12 nm is achieved. The obtained NF membrane exhibits an extremely high performance with a permeating flux of 32 L m -2 h -1 bar -1 and a rejection rate of 95.9% to divalent ions. This value is two to five times higher than the traditional NF membranes with similar rejection rate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Ultrasonographic analysis in vitro of parietal thickness of lower limb varicose veins.

    PubMed

    Bruschi, E; Como, G; Zuiani, C; Segatto, E; Rocco, M; Biasi, G; Bazzocchi, M

    2006-09-01

    The aim of this study was to evaluate the ability of ultrasound (US) to measure the parietal thickness of varicose veins. In a blind in vitro analysis, 28 great saphenous veins, obtained after stripping surgery from 28 patients with chronic venous insufficiency, were examined with a digital US scanner ATL-HDI5000, linear 5-1 to 2-MHz broadband probe, compound imaging technique and analogic-digital zooming. We obtained one to three progressive measurements for each vein wall (total 67 parietal thicknesses). The samples, fixed in formalin, were sent to the pathology laboratory: sections were obtained at the same level of the sonographic planes, and images were obtained by digital camera mounted on an optical microscope. Measurements obtained at histology were considered as the gold standard. K-statistic was applied to compare sonographic and histologic measurements. Considering only the hypoechoic wall portion, 29/29 (100%) diagnoses of hypotrophy (K=0.91), 19/22 (86%) diagnoses of normotrophy (K=0,47) and 12/16 (75%) diagnoses of hypertrophy (K=0.7) were obtained by sonography. In our preliminary experience, the in vitro study of varicose veins allows precise, at least morphological, detection of hypotrophic walls. If these preliminary data are confirmed in vivo, sonography could be used to discriminate patients eligible for conservative treatment instead of surgery.

  9. Cell wall assembly in fucus zygotes: I. Characterization of the polysaccharide components.

    PubMed

    Quatrano, R S; Stevens, P T

    1976-08-01

    Fertilization triggers the assembly of a cell wall around the egg cell of three brown algae, Fucus vesiculosus, F. distichus, and F. inflatus. New polysaccharide polymers are continually being added to the cell wall during the first 24 hours of synchronous embryo development. This wall assembly involves the extracellular deposition of fibrillar material by cytoplasmic vesicles fusing with the plasma membrane. One hour after fertilization a fragmented wall can be isolated free of cytoplasm and contains equal amounts of cellulose and alginic acid with no fucose-containing polymers (fucans) present. Birefringence of the wall caused by oriented cellulose microfibrils is not detected in all zygotes until 4 hours, at which time intact cell walls can be isolated that retain the shape of the zygote. These walls have a relatively low ratio of fucose to xylose and little sulfate when compared to walls from older embryos. When extracts of walls from 4-hour zygotes are subjected to cellulose acetate electrophoresis at pH 7, a single fucan (F(1)) can be detected. By 12 hours, purified cell walls are composed of fucans containing a relatively high ratio of fucose to xylose and high levels of sulfate, and contain a second fucan (F(2)) which is electrophoretically distinct from F(1). F(2) appears to be deposited in only a localized region of the wall, that which elongates to form the rhizoid cell. Throughout wall assembly, the polyuronide block co-polymer alginic acid did not significantly vary its mannuronic (M) to guluronic (G) acid ratio (0.33-0.55) or its block distribution (MG, 54%; GG, 30%; MM, 16%). From 6 to 24 hours of embryo development, the proportion of the major polysaccharide components found in purified walls is stable. Alginic acid is the major polymer and comprises about 60% of the total wall, while cellulose and the fucans each make-up about 20% of the remainder. During the extracellular assembly of this wall, the intracellular levels of the storage glucan

  10. Modelling ultrasound guided wave propagation for plate thickness measurement

    NASA Astrophysics Data System (ADS)

    Malladi, Rakesh; Dabak, Anand; Murthy, Nitish Krishna

    2014-03-01

    Structural Health monitoring refers to monitoring the health of plate-like walls of large reactors, pipelines and other structures in terms of corrosion detection and thickness estimation. The objective of this work is modeling the ultrasonic guided waves generated in a plate. The piezoelectric is excited by an input pulse to generate ultrasonic guided lamb waves in the plate that are received by another piezoelectric transducer. In contrast with existing methods, we develop a mathematical model of the direct component of the signal (DCS) recorded at the terminals of the piezoelectric transducer. The DCS model uses maximum likelihood technique to estimate the different parameters, namely the time delay of the signal due to the transducer delay and amplitude scaling of all the lamb wave modes due to attenuation, while taking into account the received signal spreading in time due to dispersion. The maximum likelihood estimate minimizes the energy difference between the experimental and the DCS model-generated signal. We demonstrate that the DCS model matches closely with experimentally recorded signals and show it can be used to estimate thickness of the plate. The main idea of the thickness estimation algorithm is to generate a bank of DCS model-generated signals, each corresponding to a different thickness of the plate and then find the closest match among these signals to the received signal, resulting in an estimate of the thickness of the plate. Therefore our approach provides a complementary suite of analytics to the existing thickness monitoring approaches.

  11. Intracranial Vascular Disease Evaluation With Combined Vessel Wall Imaging And Patient Specific Hemodynamics

    NASA Astrophysics Data System (ADS)

    Samson, Kurt; Mossa-Basha, Mahmud; Yuan, Chun; Canton, Maria De Gador; Aliseda, Alberto

    2017-11-01

    Intracranial vascular pathologies are evaluated with angiography, conventional digital subtraction angiography or non-invasive (MRI, CT). Current techniques present limitations on the resolution with which the vessel wall characteristics can be measured, presenting a major challenge to differential diagnostic of cerebral vasculopathies. A new combined approach is presented that incorporates patient-specific image-based CFD models with intracranial vessel-wall MRI (VWMRI). Comparisons of the VWMRI measurements, evaluated for the presence of wall enhancement and thin-walled regions, against CFD metrics such as wall shear stress (WSS), and oscillatory shear index (OSI) are used to understand how the new imaging technique developed can predict the influence of hemodynamics on the deterioration of the aneurysmal wall, leading to rupture. Additionally, histology of each resected aneurysm, evaluated for inflammatory infiltration and wall thickness features, is used to validate the analysis from VWMRI and CFD. This data presents a solid foundation on which to build a new framework for combined VWMRI-CFD to predict unstable wall changes in unruptured intracranial aneurysms, and support clinical monitoring and intervention decisions.

  12. Effect of Processing Parameters on Pore Structure and Thickness of Anodic Aluminum Oxide (AAO) Tubular Membranes.

    PubMed

    Belwalkar, A; Grasing, E; Van Geertruyden, W; Huang, Z; Misiolek, W Z

    2008-07-01

    Nanoporous anodic aluminum oxide (AAO) tubular membranes were fabricated from aluminum alloy tubes in sulfuric and oxalic acid electrolytes using a two-step anodization process. The membranes were investigated for characteristics such as pore size, interpore distance and thickness by varying applied voltage and electrolyte concentration. Morphology of the membranes was examined using light optical and scanning electron microscopy and characterized using ImageJ software. Results showed that membranes having narrow pore size and uniform pore distribution with parallel channel arrays were obtained. The pore sizes were ranging from 14 to 24 nm and the wall thicknesses as high as 76 microm. It was found that the pore size increased in direct proportion with the applied voltage and inversely with the electrolyte concentration while the interpore distance increased linearly with the applied voltage. It was also observed that increase in acid concentration increased tubular membrane wall thickness that improved mechanical handling. By using anodic alumina technology, robust ceramic tubes with uniformly distributed pore-structure and parallel nano-channels of lengths and sizes practical for industrial applications were reliably produced in quantity.

  13. Effect of Processing Parameters on Pore Structure and Thickness of Anodic Aluminum Oxide (AAO) Tubular Membranes

    PubMed Central

    Belwalkar, A.; Grasing, E.; Huang, Z.; Misiolek, W.Z.

    2008-01-01

    Nanoporous anodic aluminum oxide (AAO) tubular membranes were fabricated from aluminum alloy tubes in sulfuric and oxalic acid electrolytes using a two-step anodization process. The membranes were investigated for characteristics such as pore size, interpore distance and thickness by varying applied voltage and electrolyte concentration. Morphology of the membranes was examined using light optical and scanning electron microscopy and characterized using ImageJ software. Results showed that membranes having narrow pore size and uniform pore distribution with parallel channel arrays were obtained. The pore sizes were ranging from 14 to 24 nm and the wall thicknesses as high as 76 µm. It was found that the pore size increased in direct proportion with the applied voltage and inversely with the electrolyte concentration while the interpore distance increased linearly with the applied voltage. It was also observed that increase in acid concentration increased tubular membrane wall thickness that improved mechanical handling. By using anodic alumina technology, robust ceramic tubes with uniformly distributed pore-structure and parallel nano-channels of lengths and sizes practical for industrial applications were reliably produced in quantity. PMID:19578471

  14. A model to predict radon exhalation from walls to indoor air based on the exhalation from building material samples.

    PubMed

    Sahoo, B K; Sapra, B K; Gaware, J J; Kanse, S D; Mayya, Y S

    2011-06-01

    In recognition of the fact that building materials are an important source of indoor radon, second only to soil, surface radon exhalation fluxes have been extensively measured from the samples of these materials. Based on this flux data, several researchers have attempted to predict the inhalation dose attributable to radon emitted from walls and ceilings made up of these materials. However, an important aspect not considered in this methodology is the enhancement of the radon flux from the wall or the ceiling constructed using the same building material. This enhancement occurs mainly because of the change in the radon diffusion process from the former to the latter configuration. To predict the true radon flux from the wall based on the flux data of building material samples, we now propose a semi-empirical model involving radon diffusion length and the physical dimensions of the samples as well as wall thickness as other input parameters. This model has been established by statistically fitting the ratio of the solution to radon diffusion equations for the cases of three-dimensional cuboidal shaped building materials (such as brick, concrete block) and one dimensional wall system to a simple mathematical function. The model predictions have been validated against the measurements made at a new construction site. This model provides an alternative tool (substitute to conventional 1-D model) to estimate radon flux from a wall without relying on ²²⁶Ra content, radon emanation factor and bulk density of the samples. Moreover, it may be very useful in the context of developing building codes for radon regulation in new buildings. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. A simple, effective and clinically applicable method to compute abdominal aortic aneurysm wall stress.

    PubMed

    Joldes, Grand Roman; Miller, Karol; Wittek, Adam; Doyle, Barry

    2016-05-01

    Abdominal aortic aneurysm (AAA) is a permanent and irreversible dilation of the lower region of the aorta. It is a symptomless condition that if left untreated can expand to the point of rupture. Mechanically-speaking, rupture of an artery occurs when the local wall stress exceeds the local wall strength. It is therefore desirable to be able to non-invasively estimate the AAA wall stress for a given patient, quickly and reliably. In this paper we present an entirely new approach to computing the wall tension (i.e. the stress resultant equal to the integral of the stresses tangent to the wall over the wall thickness) within an AAA that relies on trivial linear elastic finite element computations, which can be performed instantaneously in the clinical environment on the simplest computing hardware. As an input to our calculations we only use information readily available in the clinic: the shape of the aneurysm in-vivo, as seen on a computed tomography (CT) scan, and blood pressure. We demonstrate that tension fields computed with the proposed approach agree well with those obtained using very sophisticated, state-of-the-art non-linear inverse procedures. Using magnetic resonance (MR) images of the same patient, we can approximately measure the local wall thickness and calculate the local wall stress. What is truly exciting about this simple approach is that one does not need any information on material parameters; this supports the development and use of patient-specific modelling (PSM), where uncertainty in material data is recognised as a key limitation. The methods demonstrated in this paper are applicable to other areas of biomechanics where the loads and loaded geometry of the system are known. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Wall-pressure fluctuations beneath a spatially evolving turbulent boundary layer

    NASA Astrophysics Data System (ADS)

    Mahesh, Krishnan; Kumar, Praveen

    2016-11-01

    Wall-pressure fluctuations beneath a turbulent boundary layer are important in applications dealing with structural deformation and acoustics. Simulations are performed for flat plate and axisymmetric, spatially evolving zero-pressure-gradient turbulent boundary layers at inflow Reynolds number of 1400 and 2200 based on momentum thickness. The simulations generate their own inflow using the recycle-rescale method. The results for mean velocity and second-order statistics show excellent agreement with the data available in literature. The spectral characteristics of wall-pressure fluctuations and their relation to flow structure will be discussed. This work is supported by ONR.

  17. Mimicking the Humidity Response of the Plant Cell Wall by Using Two-Dimensional Systems: The Critical Role of Amorphous and Crystalline Polysaccharides.

    PubMed

    Niinivaara, Elina; Faustini, Marco; Tammelin, Tekla; Kontturi, Eero

    2016-03-01

    Of the composite materials occurring in nature, the plant cell wall is among the most intricate, consisting of a complex arrangement of semicrystalline cellulose microfibrils in a dissipative matrix of lignin and hemicelluloses. Here, a biomimetic, two-dimensional cellulose system of the cell wall structure is introduced where cellulose nanocrystals compose the crystalline portion and regenerated amorphous cellulose composes the dissipative matrix. Spectroscopic ellipsometry and QCM-D are used to study the water vapor uptake of several two-layer systems. Quantitative analysis shows that the vapor-induced swelling of these ultrathin films can be controlled by varying ratios of the chemically identical ordered and unordered cellulose components. Intriguingly, increasing the share of crystalline cellulose appeared to increase the vapor uptake but only in cases for which the interfacial area between the crystalline and amorphous area was relatively large and the thickness of an amorphous overlayer was relatively small. The results show that a biomimetic approach may occasionally provide answers as to why certain native structures exist.

  18. Application Of Moldex3D For Thin-wall Injection Moulding Simulation

    NASA Astrophysics Data System (ADS)

    Šercer, Mladen; Godec, Damir; Bujanić, Božo

    2007-05-01

    The benefits associated with decreasing wall thicknesses below their current values are still measurable and desired even if the final wall thickness is nowhere near those of the aggressive portable electronics industry. It is important to note that gains in wall section reduction do not always occur without investment, in this case, in tooling and machinery upgrades. Equally important is the fact that productivity and performance benefits of reduced material usage, fast cycle times, and lighter weight can often outweigh most of the added costs. In order to eliminate unnecessary mould trials, minimize product development cycle, reduce overall costs and improve product quality, polymeric engineers use new CAE technology (Computer Aided Engineering). This technology is a simulation tool, which combines proven theories, material properties and process conditions to generate realistic simulations and produce valuable recommendations. Based on these recommendations, an optional combination of product design, material and process conditions can be identified. In this work, Moldex3D software was used for simulation of injection moulding in order to avoid potential moulding problems. The results gained from the simulation were used for the optimization of an existing product design, for mould development and for optimization of processing parameters, e.g. injection pressure, mould cavity temperature, etc.

  19. Horizontal-to-Vertical Spectral Ratio for Estimating Thickness of Sedimentary Deposits across the PoroTomo site in Brady Hot Springs, Nevada (USA)

    NASA Astrophysics Data System (ADS)

    Parker, L.; Fratta, D.; Zeng, X.; Lord, N. E.; Wang, H. F.; Thurber, C. H.; Lin, F. C.; Feigl, K. L.; Team, P.

    2016-12-01

    During March 2016, the PoroTomo research team deployed more than 8700 m of DAS and DTS cable in horizontal and vertical sensing arrays, 244 three-component surface geophones, inSAR images, pressure transducers, and a vibroseis truck to actively and passively image the response of a geothermal field in Brady Hot Springs, Nevada. During the imaging period the geothermal field was manipulated to change the pore pressure in the formation. The objective of the study is to invert for poroelastic parameters within a 1500 m by 500 m by 400 m volume using tomographic techniques. Among the different imaging techniques, the research team is using passive horizontal-to-vertical spectral ratio data captured with the three-component geophones to estimate the thickness of the sedimentary deposits across the PoroTomo site. The interpretation of the inverted data is complicated due the heterogeneity in the near surface deposits at the site. These deposits include diatomaceous earth, sandy/silty layers, and hardened silica associated with the presence of fumaroles. In spite of the challenges associated with deposits of very different stiffness, the mapping of sediment thickness across the Natural Laboratory helps constrain the inversion of Multiple Channel Analysis of Surface Waves to improve the quality of the solution images.

  20. The sequential changes in myocardial thickness and thickening which occur during acute transmural infarction, infarct reperfusion and the resultant expression of reperfusion injury.

    PubMed

    Turschner, Oliver; D'hooge, Jan; Dommke, Christoph; Claus, Piet; Verbeken, Erik; De Scheerder, Ivan; Bijnens, Bart; Sutherland, George R

    2004-05-01

    Successful primary PTCA (with TIMI 3 reflow) in patients with acute transmural infarction has been observed to result in an immediate abnormal increase in wall thickness associated with persisting abnormal post-systolic thickening. To understand the sequential changes in regional deformation during: (i) the development of acute transmural infarction, (ii) upon TIMI grade 3 infarct reperfusion and (iii) during the subsequent expression of reperfusion injury the following correlative experimental study was performed in a pure animal model in which there was no distal dispersion of thrombotic material causing either no reflow or secondary microvascular obstruction. In 10 closed-chest pigs, a 90 min PTCA circumflex occlusion was used to induce a transmural infarction. This was followed by 60 min of TIMI 3 infarct reperfusion. M-mode ultrasound data from the "at risk" posterior wall infarct segment and from a control remote non-ischemic septal segment were acquired at standardized time intervals. Changes in regional deformation (end-diastolic (EDWT), end-systolic (ESWT) and post-systolic (PSWT) wall thickness, end-systolic strain (epsilonES) and post-systolic strain (epsilonps)) were measured. In this pure animal model of acute transmural infarction/infarct reperfusion (with no pre-existing intra-luminal thrombus), the induced changes in wall thickness and thickening were complex. During prolonged occlusion, after an initial acute fall in ESWT, there was no further change in systolic deformation to indicate the progression of ischaemia to infarction. Both transmurally infarcted and reperfused-infarcted myocardium retained post-systolic thickening indicating that this parameter, taken in isolation, is not a consistent marker of segmental viability and, in this regard, should be interpreted only in combination with other indices of segmental function. The most striking abnormality induced by reperfusion was an immediate increase in EDWT which then increased

  1. An engineering study of hybrid adaptation of wind tunnel walls for three-dimensional testing

    NASA Technical Reports Server (NTRS)

    Brown, Clinton; Kalumuck, Kenneth; Waxman, David

    1987-01-01

    Solid wall tunnels having only upper and lower walls flexing are described. An algorithm for selecting the wall contours for both 2 and 3 dimensional wall flexure is presented and numerical experiments are used to validate its applicability to the general test case of 3 dimensional lifting aircraft models in rectangular cross section wind tunnels. The method requires an initial approximate representation of the model flow field at a given lift with wallls absent. The numerical methods utilized are derived by use of Green's source solutions obtained using the method of images; first order linearized flow theory is employed with Prandtl-Glauert compressibility transformations. Equations are derived for the flexed shape of a simple constant thickness plate wall under the influence of a finite number of jacks in an axial row along the plate centerline. The Green's source methods are developed to provide estimations of residual flow distortion (interferences) with measured wall pressures and wall flow inclinations as inputs.

  2. Optical coherence tomography assessment of vessel wall degradation in aneurysmatic thoracic aortas

    NASA Astrophysics Data System (ADS)

    Real, Eusebio; Eguizabal, Alma; Pontón, Alejandro; Val-Bernal, J. Fernando; Mayorga, Marta; Revuelta, José M.; López-Higuera, José; Conde, Olga M.

    2013-06-01

    Optical coherence tomographic images of ascending thoracic human aortas from aneurysms exhibit disorders on the smooth muscle cell structure of the media layer of the aortic vessel as well as elastin degradation. Ex-vivo measurements of human samples provide results that correlate with pathologist diagnosis in aneurysmatic and control aortas. The observed disorders are studied as possible hallmarks for aneurysm diagnosis. To this end, the backscattering profile along the vessel thickness has been evaluated by fitting its decay against two different models, a third order polynomial fitting and an exponential fitting. The discontinuities present on the vessel wall on aneurysmatic aortas are slightly better identified with the exponential approach. Aneurysmatic aortic walls present uneven reflectivity decay when compared with healthy vessels. The fitting error has revealed as the most favorable indicator for aneurysm diagnosis as it provides a measure of how uniform is the decay along the vessel thickness.

  3. Correlation of neutrophil/lymphocyte and platelet/lymphocyte ratio with visual acuity and macular thickness in age-related macular degeneration

    PubMed Central

    Sengul, Elvan Alper; Artunay, Ozgur; Kockar, Alev; Afacan, Ceyda; Rasier, Rifat; Gun, Palmet; Yalcin, Nazli Gul; Yuzbasioglu, Erdal

    2017-01-01

    AIM To investigate the place of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in the diagnosis of and prognosis for neovascular age-related macular degeneration (AMD). METHODS One hundred AMD patients and 100 healthy controls were included in the study. Blood samples were obtained from the venous blood, which is used for routine analysis, and these samples were subjected to complete blood count. NLR was defined as the neutrophil count divided by the number of lymphocytes, and PLR was defined as the platelet count divided by the number of lymphocytes. RESULTS No statistically significant difference was observed between the two groups under consideration in terms of demographic features (P>0.05). The average NLR in the patient group was found to be significantly higher than that in the healthy control group (P<0.05). The average PLR was significantly higher in the patient group as compared to the control group (P<0.05). As best corrected visual acuity (BCVA) increased, both NLR and PLR decreased (significant negative correlations at 49.8% and 63.0%, respectively), whereas as central macular thickness (CMT) increased, both NLR and PLR increased (significant positive correlations at 59.3% and 70.0%, respectively). CONCLUSION NLR and PLR levels are higher among neovascular AMD patients as compared to healthy control group. NLR and PLR levels were found to be inversely proportional to BCVA and directly proportional to CMT. PMID:28546933

  4. The ratio of change in muscle thickness between superficial and deep cervical flexor muscles during the craniocervical flexion test and a suggestion regarding clinical treatment of patients with musculoskeletal neck pain.

    PubMed

    Goo, Miran; Kim, Seong-Gil; Jun, Deokhoon

    2015-08-01

    [Purpose] The purpose of this study was to identify the imbalance of muscle recruitment in cervical flexor muscles during the craniocervical flexion test by using ultrasonography and to propose the optimal level of pressure in clinical craniocervical flexion exercise for people with neck pain. [Subjects and Methods] A total of 18 students (9 males and 9 females) with neck pain at D University in Gyeongsangbuk-do, South Korea, participated in this study. The change in muscle thickness in superficial and deep cervical flexor muscles during the craniocervical flexion test was measured using ultrasonography. The ratio of muscle thickness changes between superficial and deep muscles during the test were obtained to interpret the imbalance of muscle recruitment in cervical flexor muscles. [Results] The muscle thickness ratio of the sternocleidomastoid muscle/deep cervical flexor muscles according to the incremental pressure showed significant differences between 22 mmHg and 24 mmHg, between 24 mmHg and 28 mmHg, between 24 mmHg and 30 mmHg, and between 26 mmHg and 28 mmHg. [Conclusion] Ultrasonography can be applied for examination of cervical flexor muscles in clinical environment, and practical suggestion for intervention exercise of craniocervical flexors can be expected on the pressure level between 24 mmHg and 26 mmHg enabling the smallest activation of the sternocleidomastoid muscle.

  5. Structure reconstruction of TiO2-based multi-wall nanotubes: first-principles calculations.

    PubMed

    Bandura, A V; Evarestov, R A; Lukyanov, S I

    2014-07-28

    A new method of theoretical modelling of polyhedral single-walled nanotubes based on the consolidation of walls in the rolled-up multi-walled nanotubes is proposed. Molecular mechanics and ab initio quantum mechanics methods are applied to investigate the merging of walls in nanotubes constructed from the different phases of titania. The combination of two methods allows us to simulate the structures which are difficult to find only by ab initio calculations. For nanotube folding we have used (1) the 3-plane fluorite TiO2 layer; (2) the anatase (101) 6-plane layer; (3) the rutile (110) 6-plane layer; and (4) the 6-plane layer with lepidocrocite morphology. The symmetry of the resulting single-walled nanotubes is significantly lower than the symmetry of initial coaxial cylindrical double- or triple-walled nanotubes. These merged nanotubes acquire higher stability in comparison with the initial multi-walled nanotubes. The wall thickness of the merged nanotubes exceeds 1 nm and approaches the corresponding parameter of the experimental patterns. The present investigation demonstrates that the merged nanotubes can integrate the two different crystalline phases in one and the same wall structure.

  6. Comparison of Current and Field Driven Domain Wall Motion in Beaded Permalloy Nanowires

    NASA Astrophysics Data System (ADS)

    Lage, Enno; Dutta, Sumit; Ross, Caroline A.

    2015-03-01

    Domain wall based devices are promising candidates for non-volatile memory devices with no static power consumption. A common approach is the use of (field assisted) current driven domain wall motion in magnetic nanowires. In such systems local variations in linewidth act as obstacles for propagating domain walls. In this study we compare simulated field driven and current driven domain wall motion in permalloy nanowires with anti-notches. The simulations were obtained using the Object Oriented MicroMagnetics Framework (OOMMF). The wires with a constant thickness of 8 nm exhibit linewidths ranging from 40 nm to 300 nm. Circular shaped anti-notches extend the linewidth locally by 10% to 30% and raise information about the domain wall propagation in such beaded nanowires. The results are interpreted in terms of the observed propagation behavior and summarized in maps indicating ranges of different ability to overcome the pinning caused by anti-notches of different sizes. Furthermore, regimes of favored domain wall type (transverse walls or vortex walls) and complex propagation effects like walker breakdown behavior or dynamic change between domain wall structures are identified The authors thank the German Academic Exchange Service (DAAD) for funding.

  7. Thick strings, the liquid crystal blue phase, and cosmological large-scale structure

    NASA Technical Reports Server (NTRS)

    Luo, Xiaochun; Schramm, David N.

    1992-01-01

    A phenomenological model based on the liquid crystal blue phase is proposed as a model for a late-time cosmological phase transition. Topological defects, in particular thick strings and/or domain walls, are presented as seeds for structure formation. It is shown that the observed large-scale structure, including quasi-periodic wall structure, can be well fitted in the model without violating the microwave background isotropy bound or the limits from induced gravitational waves and the millisecond pulsar timing. Furthermore, such late-time transitions can produce objects such as quasars at high redshifts. The model appears to work with either cold or hot dark matter.

  8. Dry granular avalanche impact force on a rigid wall of semi-infinite height

    NASA Astrophysics Data System (ADS)

    Albaba, Adel; Lambert, Stéphane; Faug, Thierry

    2017-06-01

    The present paper tackles the problem of the impact of a dry granular avalanche-flow on a rigid wall of semi-infinite height. An analytic force model based on depth-averaged shock theory is proposed to describe the flow-wall interaction and the resulting impact force on the wall. Provided that the analytic force model is fed with the incoming flow conditions regarding thickness, velocity and density, all averaged over a certain distance downstream of the undisturbed incoming flow, it reproduces very well the time history of the impact force actually measured by detailed discrete element simulations, for a wide range of slope angles.

  9. Complex oxide ferroelectrics: Electrostatic doping by domain walls

    DOE PAGES

    Maksymovych, Petro

    2015-06-19

    Electrically conducting interfaces can form, rather unexpectedly, by breaking the translational symmetry of electrically insulating complex oxides. For example, a nanometre-thick heteroepitaxial interface between electronically insulating LaAlO 3 and SrTiO 3 supports a 2D electron gas1 with high mobility of >1,000 cm 2 V -1 s -1 (ref. 2). Such interfaces can exhibit magnetism, superconductivity and phase transitions that may form the functional basis of future electronic devices2. A peculiar conducting interface can be created within a polar ferroelectric oxide by breaking the translational symmetry of the ferroelectric order parameter and creating a so-called ferroelectric domain wall (Fig. 1a,b). Ifmore » the direction of atomic displacements changes at the wall in such a way as to create a discontinuity in the polarization component normal to the wall (Fig. 1a), the domain wall becomes electrostatically charged. It may then attract compensating mobile charges of opposite sign produced by dopant ionization, photoexcitation or other effects, thereby locally, electrostatically doping the host ferroelectric film. In contrast to conductive interfaces between epitaxially grown oxides, domain walls can be reversibly created, positioned and shaped by electric fields, enabling reconfigurable circuitry within the same volume of the material. Now, writing in Nature Nanotechnology, Arnaud Crassous and colleagues at EPFL and University of Geneva demonstrate control and stability of charged conducting domain walls in ferroelectric thin films of BiFeO 3 down to the nanoscale.« less

  10. Impaction and Prediction: Does Ureteral Wall Thickness Affect the Success of Medical Expulsive Therapy in Pediatric Ureteral Stones?

    PubMed

    Tuerxun, Aierken; Batuer, Abudukahaer; Erturhan, Sakip; Eryildirim, Bilal; Camur, Emre; Sarica, Kemal

    2017-01-01

    The study aimed to evaluate the predictive value of ureteral wall thickness (UWT) and stone-related parameters for medical expulsive therapy (MET) success with an alpha blocker in pediatric upper ureteral stones. A total of 35 children receiving MET ureteral stones (<10 mm) were evaluated. Patients were divided into 2 subgroups where MET was successful in 18 children (51.4%) and unsuccessful in 17 children (48.6%). Prior to management, stone size, stone density (in Hounsfield unit), degree of hydronephrosis, and UWT were evaluated with patient demographics and recorded. The possible predictive value of these parameters in success rates and time to stone expulsion were evaluated in a comparative manner between the 2 groups. The overall mean patient age and stone size values were 5.40 ± 0.51 years and 6.24 ± 0.28 mm, respectively. Regarding the predictive values of these parameters for the success of MET, while stone size and UWT were found to be highly predictive for MET success, patients age, body mass index, stone density, and degree of hydronephrosis had no predictive value on this aspect. Our findings indicated that some stone and anatomical factors may be used to predict the success of MET in pediatric ureteral stones in an effective manner. With this approach, unnecessary use of these drugs that may cause a delay in removing the stone will be avoided, and the possible adverse effects of obstruction as well as stone-related clinical symptoms could be minimized. © 2017 S. Karger AG, Basel.

  11. Long-term fuel retention in JET ITER-like wall

    NASA Astrophysics Data System (ADS)

    Heinola, K.; Widdowson, A.; Likonen, J.; Alves, E.; Baron-Wiechec, A.; Barradas, N.; Brezinsek, S.; Catarino, N.; Coad, P.; Koivuranta, S.; Krat, S.; Matthews, G. F.; Mayer, M.; Petersson, P.; Contributors, JET

    2016-02-01

    Post-mortem studies with ion beam analysis, thermal desorption, and secondary ion mass spectrometry have been applied for investigating the long-term fuel retention in the JET ITER-like wall components. The retention takes place via implantation and co-deposition, and the highest retention values were found to correlate with the thickness of the deposited impurity layers. From the total amount of retained D fuel over half was detected in the divertor region. The majority of the retained D is on the top surface of the inner divertor, whereas the least retention was measured in the main chamber on the mid-plane of the inner wall limiter. The recessed areas of the inner wall showed significant contribution to the main chamber total retention. Thermal desorption spectroscopy analysis revealed the energetic T from DD reactions being implanted in the divertor. The total T inventory was assessed to be \\gt 0.3 {{mg}}.

  12. Non-exposed endoscopic wall-inversion surgery for gastrointestinal stromal tumor

    PubMed Central

    Mitsui, Takashi; Aikou, Susumu; Niimi, Keiko; Fujishiro, Mitsuhiro; Seto, Yasuyuki

    2018-01-01

    Laparoscopic and endoscopic cooperative surgery (LECS) is an accepted method of laparoscopic wedge resection, which is minimally invasive, for gastrointestinal stromal tumors (GISTs). We established a type of LECS achieving a full-thickness resection, non-exposed endoscopic wall-inversion surgery (NEWS), in an effort to prevent exposure of the peritoneal cavity to gastric intraluminal contents. We employed this surgical technique in 28 gastric GIST patients. We failed to complete NEWS in the initial two patients and in one patient with a large tumor (40 mm × 35 mm), but otherwise carried out the procedure successfully. Although a learning effect is speculated to occur, based on a decreasing trend in the operation time, the median operation time was 184 minutes showing that NEWS is still a time-consuming method. No significant differences were recognized in tumor size or location, except near the esophagogastric junction (EGJ), nor in the cross-sectional circumference. NEWS is feasible and appears to be a good option, especially for small GISTs with mucosal ulceration rendering full-thickness enucleation by opening of the gastric wall unfeasible. PMID:29682624

  13. The rotation of cellulose synthase trajectories is microtubule dependent and influences the texture of epidermal cell walls in Arabidopsis hypocotyls.

    PubMed

    Chan, Jordi; Crowell, Elizabeth; Eder, Magdalena; Calder, Grant; Bunnewell, Susan; Findlay, Kim; Vernhettes, Samantha; Höfte, Herman; Lloyd, Clive

    2010-10-15

    Plant shoots have thick, polylamellate outer epidermal walls based on crossed layers of cellulose microfibrils, but the involvement of microtubules in such wall lamellation is unclear. Recently, using a long-term movie system in which Arabidopsis seedlings were grown in a biochamber, the tracks along which cortical microtubules move were shown to undergo slow rotary movements over the outer surface of hypocotyl epidermal cells. Because microtubules are known to guide cellulose synthases over the short term, we hypothesised that this previously unsuspected microtubule rotation could, over the longer term, help explain the cross-ply structure of the outer epidermal wall. Here, we test that hypothesis using Arabidopsis plants expressing the cellulose synthase GFP-CESA3 and show that cellulose synthase trajectories do rotate over several hours. Neither microtubule-stabilising taxol nor microtubule-depolymerising oryzalin affected the linear rate of GFP-CESA3 movement, but both stopped the rotation of cellulose synthase tracks. Transmission electron microscopy revealed that drug-induced suppression of rotation alters the lamellation pattern, resulting in a thick monotonous wall layer. We conclude that microtubule rotation, rather than any hypothetical mechanism for wall self-assembly, has an essential role in developing cross-ply wall texture.

  14. Using H/V Spectral Ratio Analysis to Map Sediment Thickness and to Explain Macroseismic Intensity Variation of a Low-Magnitude Seismic Swarm in Central Belgium

    NASA Astrophysics Data System (ADS)

    Van Noten, K.; Lecocq, T.; Camelbeeck, T.

    2013-12-01

    Between 2008 and 2010, the Royal Observatory of Belgium received numerous ';Did You Feel It'-reports related to a 2-year lasting earthquake swarm at Court-Saint-Etienne, a small town in a hilly area 20 km SE of Brussels, Belgium. These small-magnitude events (-0.7 ≤ ML ≤ 3.2, n = c. 300 events) were recorded both by the permanent seismometer network in Belgium and by a locally installed temporary seismic network deployed in the epicentral area. Relocation of the hypocenters revealed that the seismic swarm can be related to the reactivation of a NW-SE strike-slip fault at 3 to 6 km depth in the basement rocks of the Lower Palaeozoic London-Brabant Massif. This sequence caused a lot of emotion in the region because more than 60 events were felt by the local population. Given the small magnitudes of the seismic swarm, most events were more often heard than felt by the respondents, which is indicative of a local high-frequency earthquake source. At places where the bedrock is at the surface or where it is covered by thin alluvial sediments (<10 m), such as in incised river valleys and on hill slopes, reported macroseismic intensities are higher than those on hill tops where respondents live on a thicker Quaternary and Cenozoic sedimentary cover (> 30 m). In those river valleys that have a considerable alluvial sedimentary cover, macroseismic intensities are again lower. To explain this variation in macroseismic intensity we present a macroseismic analysis of all DYFI-reports related to the 2008-2010 seismic swarm and a pervasive H/V spectral ratio (HVSR) analysis of ambient noise measurements to model the thickness of sediments covering the London-Brabant Massif. The HVSR method is a very powerful tool to map the basement morphology, particularly in regions of unknown subsurface structure. By calculating the soil's fundamental frequency above boreholes, we calibrated the power-law relationship between the fundamental frequency, shear wave velocity and the thickness

  15. Nonlinear analysis of composite thin-walled helicopter blades

    NASA Astrophysics Data System (ADS)

    Kalfon, J. P.; Rand, O.

    Nonlinear theoretical modeling of laminated thin-walled composite helicopter rotor blades is presented. The derivation is based on nonlinear geometry with a detailed treatment of the body loads in the axial direction which are induced by the rotation. While the in-plane warping is neglected, a three-dimensional generic out-of-plane warping distribution is included. The formulation may also handle varying thicknesses and mass distribution along the cross-sectional walls. The problem is solved by successive iterations in which a system of equations is constructed and solved for each cross-section. In this method, the differential equations in the spanwise directions are formulated and solved using a finite-differences scheme which allows simple adaptation of the spanwise discretization mesh during iterations.

  16. Research on the effect of wall corrosion and rim seal on the withdrawal loss for a floating roof tank.

    PubMed

    Wang, Yongqiang; Liu, Minmin; Liu, Fang; Zhao, Chaocheng; Zhao, Dongfeng; Han, Fenglei; Liu, Chunshuang

    2018-04-25

    Storage tanks are important parts of volatile organic compound (VOC) fugitive emission sources of the petrochemical industry; the floating roof tank is the main oil storage facility at present. Based on the mechanism of withdrawal loss and the type of rim seal, octane and gasoline were taken as the research objects. A model instrument for simulating the oil loading process by the 316 stainless steel and A3 carbon steel as the test piece was designed, and the film thickness was measured by wet film thickness gauge to investigate the influence of the corrosion of the tank wall and rim seal on the withdrawal loss for floating roof tanks. It was found that withdrawal loss was directly proportional to the shell factor, and the oil thickness of the octane and gasoline increased with the strength of the wall corrosion with the same wall material and rim seal. Compared with the untreated test piece, the oil film thickness of the octane/gasoline was increased by 7.04~8.57 μm/13.14~21.93 μm and 5.59~11.49 μm/11.61~25.48 μm under the corrosion of hydrochloric acid for 32 and 75 h, respectively. The oil film thickness of octane and gasoline decreased with the increasing of the rim seal, and the oil film thickness of the octane decreased by 11.97~28.90% and 37.32~73.83% under the resilient-filled seal and the double seal, respectively. The gasoline dropped by 11.97~31.18% and 45.98~75.34% under the resilient-filled seal and the double seal, respectively. In addition, the tank surface roughness reduced the compression of the rim seal on the tank wall, and the effect of scraping decreased. The API withdrawal loss formula for a floating roof tank was recommended to take into account the effect of the rim seal to improve the accuracy of the loss evaluation. Finally, some measures of reducing the withdrawal loss were proposed.

  17. Driving chiral domain walls in antiferromagnets using rotating magnetic fields

    NASA Astrophysics Data System (ADS)

    Pan, Keming; Xing, Lingdi; Yuan, H. Y.; Wang, Weiwei

    2018-05-01

    We show theoretically and numerically that an antiferromagnetic domain wall can be moved by a rotating magnetic field in the presence of Dzyaloshinskii-Moriya interaction (DMI). Two motion modes are found: rigid domain wall motion at low frequency (corresponding to the perfect frequency synchronization) and the oscillating motion at high frequency. In the full synchronized region, the steady velocity of the domain wall is universal, in the sense that it depends only on the frequency of the rotating field and the ratio between DMI strength and exchange constant. The domain wall velocity is independent of the Gilbert damping and the rotating field strength. Moreover, a rotating field in megahertz is sufficient to move the antiferromagnetic domain wall.

  18. Lactate: creatinine ratio in babies with thin meconium staining of amniotic fluid.

    PubMed

    Ojha, Rishi Kant; Singh, Saroj K; Batra, Sanjay; Sreenivas, V; Puliyel, Jacob M

    2006-04-20

    ACOG states meconium stained amniotic fluid (MSAF) as one of the historical indicators of perinatal asphyxia. Thick meconium along with other indicators is used to identify babies with severe intrapartum asphyxia. Lactate creatinine ratio (L:C ratio) of 0.64 or higher in first passed urine of babies suffering severe intrapartum asphyxia has been shown to predict Hypoxic Ischaemic Encephalopathy (HIE). Literature review shows that meconium is passed in distress and thin meconium results from mixing and dilution over time, which may be hours to days. Thin meconium may thus be used as an indicator of antepartum asphyxia. We tested L:C ratios in a group of babies born through thin and thick meconium, and for comparison, in a group of babies without meconium at birth. 86 consecutive newborns, 36 to 42 weeks of gestation, with meconium staining of liquor, were recruited for the study. 52 voided urine within 6 hours of birth; of these 27 had thick meconium and 25 had thin meconium at birth. 42 others, who did not have meconium or any other signs of asphyxia at birth provided controls. Lactate and creatinine levels in urine were tested by standard enzymatic methods in the three groups. Lactate values are highest in the thin MSAF group followed by the thick MSAF and controls. Creatinine was lowest in the thin MSAF, followed by thick MSAF and controls. Normal babies had an average L:C ratio of 0.13 (+/- 0.09). L:C ratio was more among thin MSAF babies (4.3 +/- 11.94) than thick MSAF babies (0.35 +/- 0.35). Median L:C ratio was also higher in the thin MSAF group. Variation in the values of these parameters is observed to be high in the thin MSAF group as compared to other groups. L:C ratio was above the cutoff of 0.64 of Huang et al in 40% of those with thin meconium. 2 of these developed signs of HIE with convulsions (HIE Sarnat and Sarnat Stage II) during hospital stay. One had L:C Ratio of 93 and the other of 58.6. A smaller proportion (20%) of those with thick meconium

  19. Uniform, dense arrays of vertically aligned, large-diameter single-walled carbon nanotubes.

    PubMed

    Han, Zhao Jun; Ostrikov, Kostya

    2012-04-04

    Precisely controlled reactive chemical vapor synthesis of highly uniform, dense arrays of vertically aligned single-walled carbon nanotubes (SWCNTs) using tailored trilayered Fe/Al(2)O(3)/SiO(2) catalyst is demonstrated. More than 90% population of thick nanotubes (>3 nm in diameter) can be produced by tailoring the thickness and microstructure of the secondary catalyst supporting SiO(2) layer, which is commonly overlooked. The proposed model based on the atomic force microanalysis suggests that this tailoring leads to uniform and dense arrays of relatively large Fe catalyst nanoparticles on which the thick SWCNTs nucleate, while small nanotubes and amorphous carbon are effectively etched away. Our results resolve a persistent issue of selective (while avoiding multiwalled nanotubes and other carbon nanostructures) synthesis of thick vertically aligned SWCNTs whose easily switchable thickness-dependent electronic properties enable advanced applications in nanoelectronic, energy, drug delivery, and membrane technologies.

  20. Modeling of thin, back-wall silicon solar cells

    NASA Technical Reports Server (NTRS)

    Baraona, C. R.

    1979-01-01

    The performance of silicon solar cells with p-n junctions on the nonilluminated surface (i.e., upside-down or back-wall cells) was calculated. These structures consisted of a uniformly shaped p-type substrate layer, a p(+)-type field layer on the front (illuminated) surface, and a shallow, n-type junction on the back (nonilluminated) surface. A four-layer solar cell model was used to calculate efficiency, open-circuit voltage, and short-circuit current. The effect on performance of p-layer thickness and resistivity was determined. The diffusion length was varied to simulate the effect of radiation damage. The results show that peak initial efficiencies greater than 15 percent are possible for cell thicknesses or 100 micrometers or less. After 10 years of radiation damage in geosynchronous orbit, thin (25 to 50 micrometers thick) cells made from 10 to 100 ohm cm material show the smallest decrease (approximately 10 percent) in performance.