WorldWideScience

Sample records for diameter elastic blood

  1. Diameter-dependent thermodynamic and elastic properties of metallic nanoparticles

    Science.gov (United States)

    Chandra, Jeewan; Kholiya, Kuldeep

    2015-04-01

    A simple theoretical model has been proposed to study the diameter-dependent properties of metallic nanoparticles, i.e. Ag, Au, Al, Ni, Pb, Cu and Fe. The diameter-dependent thermodynamic properties includes melting temperature, Debye temperature, evaporation temperature, melting enthapy and melting entropy. The model is also extended to study the diameter-dependent elastic properties including bulk modulus, Young's modulus and thermal expansion coefficient. On comparison with available experimental findings and other theoretical approaches, the results obtained with the present formulation depict a close agreement and demonstrate the validity of the method proposed in the present paper.

  2. Photoacoustic determination of blood vessel diameter.

    NARCIS (Netherlands)

    Kolkman, R.G.; Klaessens, J.H.G.M.; Hondebrink, E.; Hopman, J.C.W.; Mul, F.F. de; Steenbergen, W.; Thijssen, J.M.; Leeuwen, T.G. van

    2004-01-01

    A double-ring sensor was applied in photoacoustic tomographic imaging of artificial blood vessels as well as blood vessels in a rabbit ear. The peak-to-peak time (tau(pp)) of the laser (1064 nm) induced pressure transient was used to estimate the axial vessel diameter. Comparison with the actual ves

  3. Heritability of retinal vessel diameters and blood pressure

    DEFF Research Database (Denmark)

    Taarnhøj, Nina C B B; Larsen, Michael; Sander, Birgit

    2006-01-01

    PURPOSE: To assess the relative influence of genetic and environmental effects on retinal vessel diameters and blood pressure in healthy adults, as well as the possible genetic connection between these two characteristics. METHODS: In 55 monozygotic and 50 dizygotic same-sex healthy twin pairs......%-80%) for CRAE, 83% (95% CI: 73%-89%) for CRVE, and 61% (95% CI: 44%-73%) for mean arterial blood pressure (MABP). Retinal artery diameter decreased with increasing age and increasing arterial blood pressure. Mean vessel diameters in the population were 165.8 +/- 14.9 microm for CRAE, 246.2 +/- 17.7 microm...... and blood glucose, variations in retinal blood vessel diameters and blood pressure were predominantly attributable to genetic effects. A genetic influence may have a role in individual susceptibility to hypertension and other vascular diseases. The results suggest that retinal vessel diameters...

  4. On the Elastic Vibration Model for High Length-Diameter Ratio Rocket with Attitude Control System

    Institute of Scientific and Technical Information of China (English)

    朱伯立; 杨树兴

    2003-01-01

    An elastic vibration model for high length-diameter ratio spinning rocket with attitude control system which can be used for trajectory simulation is established. The basic theory of elastic dynamics and vibration dynamics were both used to set up the elastic vibration model of rocket body. In order to study the problem more conveniently, the rocket's body was simplified to be an even beam with two free ends. The model was validated by simulation results and the test data.

  5. Heritability of retinal vessel diameters and blood pressure

    DEFF Research Database (Denmark)

    Taarnhøj, Nina C B B; Larsen, Michael; Sander, Birgit

    2006-01-01

    PURPOSE: To assess the relative influence of genetic and environmental effects on retinal vessel diameters and blood pressure in healthy adults, as well as the possible genetic connection between these two characteristics. METHODS: In 55 monozygotic and 50 dizygotic same-sex healthy twin pairs......%-80%) for CRAE, 83% (95% CI: 73%-89%) for CRVE, and 61% (95% CI: 44%-73%) for mean arterial blood pressure (MABP). Retinal artery diameter decreased with increasing age and increasing arterial blood pressure. Mean vessel diameters in the population were 165.8 +/- 14.9 microm for CRAE, 246.2 +/- 17.7 microm...... for CRVE, and 0.67 +/- 0.05 microm for AVR. No significant influence on artery or vein diameters was found for gender, smoking, body mass index (BMI), total cholesterol, fasting blood glucose, or 2-hour oral glucose tolerance test values. CONCLUSIONS: In healthy young adults with normal blood pressure...

  6. NONLINEAR ELASTICITY OF BLOOD ARTERIAL DUCT

    Institute of Scientific and Technical Information of China (English)

    黄孟才; 顾忠; 沈俊; 唐复勇

    1991-01-01

    The paper deals with nonlinear elasticity of blood arterial duct, in which the artery is modeled to bea locally triclinic, transverse isotropic, incorapressible, axisymmetric and thickwalled tube with large deformations, The nonlinear coustitutive relationship of arterial tissues is based on the theorv of Green and Adkins. A nonlinear strain energy density function is introduced for nonlinear stress-strain relationship of second order, in which the coefficient of each term is expressed by means of a Lame’s constant, The elasticity constants are nqcessary to describe such a uonlinear finite strain etastieity of the second order, These constants are determined by means of the stress-strain increment theory.

  7. Electrospun biodegradable elastic polyurethane scaffolds with dipyridamole release for small diameter vascular grafts.

    Science.gov (United States)

    Punnakitikashem, Primana; Truong, Danh; Menon, Jyothi U; Nguyen, Kytai T; Hong, Yi

    2014-11-01

    Acellular biodegradable small diameter vascular grafts (SDVGs) require antithrombosis, intimal hyperplasia inhibition and rapid endothelialization to improve the graft patency. However, current antithrombosis and antiproliferation approaches often conflict with endothelial cell layer formation on SDVGs. To address this limitation, biodegradable elastic polyurethane urea (BPU) and the drug dipyridamole (DPA) were mixed and then electrospun into a biodegradable fibrous scaffold. The BPU would provide the appropriate mechanical support, while the DPA in the scaffold would offer biofunctions as required above. We found that the resulting scaffolds had tensile strengths and strains comparable with human coronary artery. The DPA in the scaffolds was continuously released up to 91 days in phosphate buffer solution at 37 °C, with a low burst release within the first 3 days. Compared to BPU alone, improved non-thrombogenicity of the DPA-loaded BPU scaffolds was evidenced with extended human blood clotting time, lower TAT complex concentration, lower hemolysis and reduced human platelet deposition. The scaffolds with a higher DPA content (5 and 10%) inhibited proliferation of human aortic smooth muscle cell significantly. Furthermore, the DPA-loaded scaffolds had no adverse effect on human aortic endothelial cell growth, yet it improved their proliferation. The attractive mechanical properties and biofunctions of the DPA-loaded BPU scaffold indicate its potential as an acellular biodegradable SDVG for vascular replacement.

  8. PERFORMANCE MODELING AND ANALYSIS OF BLOOD FLOW IN ELASTIC ARTERIES

    Institute of Scientific and Technical Information of China (English)

    Anil Kumar; C.L. Varshney; G.C. Sharma

    2005-01-01

    Two different non-Newtonian models for blood flow are considered, first a simple power law model displaying shear thinning viscosity, and second a generalized Maxwell model displaying both shear thinning viscosity and oscillating flow viscous-elasticity. These models are used along with a Newtonian model to study sinusoidal flow of blood in rigid and elastic straight arteries in the presence of magnetic field. The elasticity of blood does not appear to influence its flow behavior under physiological conditions in the large arteries,purely viscous shear thinning model should be quite realistic for simulating blood flow under these conditions. On using the power law model with high shear rate for sinusoidal flow simulation in elastic arteries, the mean and amplitude of the flow rate were found to be lower for a power law fluid compared to Newtonian fluid for the same pressure gradient. The governing equations have been solved by Crank-Niclson scheme. The results are interpreted in the context of blood in the elastic arteries keeping the magnetic effects in view. For physiological flow simulation in the aorta, an increase in mean wall shear stress, but a reduction in peak wall shear stress were observed for power law model compared to a Newtonian fluid model for matched flow rate wave form. Blood flow in the presence of transverse magnetic field in an elastic artery is investigated and the influence of factors such as morphology and surface irregularity is evaluated.

  9. Anatomical and Functional Estimations of Brachial Artery Diameter and Elasticity Using Oscillometric Measurements with a Quantitative Approach

    OpenAIRE

    Yoshinaga, Keiichiro; Fujii, Satoshi; Tomiyama, Yuuki; Takeuchi, Keisuke; Tamaki, Nagara

    2016-01-01

    Noninvasive vascular function measurement plays an important role in detecting early stages of atherosclerosis and in evaluating therapeutic responses. In this regard, recently, new vascular function measurements have been developed. These new measurements have been used to evaluate vascular function in coronary arteries, large aortic arteries, or peripheral arteries. Increasing vascular diameter represents vascular remodeling related to atherosclerosis. Attenuated vascular elasticity may be ...

  10. Rheology of red blood cells under flow in highly confined microchannels: I. effect of elasticity.

    Science.gov (United States)

    Lázaro, Guillermo R; Hernández-Machado, Aurora; Pagonabarraga, Ignacio

    2014-10-07

    We analyze the rheology of dilute red blood cell suspensions in pressure driven flows at low Reynolds number, in terms of the morphologies and elasticity of the cells. We focus on narrow channels of width similar to the cell diameter, when the interactions with the walls dominate the cell dynamics. The suspension presents a shear-thinning behaviour, with a Newtonian-behaviour at low shear rates, an intermediate region of strong decay of the suspension viscosity, and an asymptotic regime at high shear rates in which the effective viscosity converges to that of the solvent. We identify the relevant aspects of cell elasticity that contribute to the rheological response of blood at high confinement. In a second paper, we will explore the focusing of red blood cells while flowing at high shear rates and how this effect is controlled by the geometry of the channel.

  11. Anatomical and Functional Estimations of Brachial Artery Diameter and Elasticity Using Oscillometric Measurements with a Quantitative Approach.

    Science.gov (United States)

    Yoshinaga, Keiichiro; Fujii, Satoshi; Tomiyama, Yuuki; Takeuchi, Keisuke; Tamaki, Nagara

    2016-07-01

    Noninvasive vascular function measurement plays an important role in detecting early stages of atherosclerosis and in evaluating therapeutic responses. In this regard, recently, new vascular function measurements have been developed. These new measurements have been used to evaluate vascular function in coronary arteries, large aortic arteries, or peripheral arteries. Increasing vascular diameter represents vascular remodeling related to atherosclerosis. Attenuated vascular elasticity may be a reliable marker for atherosclerotic risk assessment. However, previous measurements for vascular diameter and vascular elasticity have been complex, operator-dependent, or invasive. Therefore, simple and reliable approaches have been sought. We recently developed a new automated oscillometric method to measure the estimated area (eA) of a brachial artery and its volume elastic modulus (VE). In this review, we further report on this new measurement and other vascular measurements. We report on the reliability of the new automated oscillometric measurement of eA and VE. Based on our findings, this measurement technique should be a reliable approach, and this modality may have practical application to automatically assess muscular artery diameter and elasticity in clinical or epidemiological settings. In this review, we report the characteristics of our new oscillometric measurements and other related vascular function measurements.

  12. Skin blood flow with elastic compressive extravehicular activity space suit.

    Science.gov (United States)

    Tanaka, Kunihiko; Gotoh, Taro M; Morita, Hironobu; Hargens, Alan R

    2003-10-01

    During extravehicular activity (EVA), current space suits are pressurized with 100% oxygen at approximately 222 mmHg. A tight elastic garment, or mechanical counter pressure (MCP) suit that generates pressure by compression, may have several advantages over current space suit technology. In this study, we investigated local microcirculatory effects produced with negative ambient pressure with an MCP sleeve. The MCP glove and sleeve generated pressures similar to the current space suit. MCP remained constant during negative pressure due to unchanged elasticity of the material. Decreased skin capillary blood flow and temperature during MCP compression was counteracted by greater negative pressure or a smaller pressure differential.

  13. Estimation of vessel diameter and blood flow dynamics from laser speckle images

    DEFF Research Database (Denmark)

    Postnov, Dmitry D.; Tuchin, Valery V.; Sosnovtseva, Olga

    2016-01-01

    Laser speckle imaging is a rapidly developing method to study changes of blood velocity in the vascular networks. However, to assess blood flow and vascular responses it is crucial to measure vessel diameter in addition to blood velocity dynamics. We suggest an algorithm that allows for dynamical...... masking of a vessel position and measurements of it's diameter from laser speckle images. This approach demonstrates high reliability and stability....

  14. Development of novel short-term heating angioplasty: diameter and elasticity change of vascular wall ex vivo

    Science.gov (United States)

    Shimazaki, Natsumi; Kaneko, Kenji; Nakatani, Eriko; Arai, Tsunenori

    2007-02-01

    In order to investigate the optimum operation parameters on novel short-term heating (angioplasty in which we demonstrated sufficient vascular dilatation with lower pressure by heat- induced denaturation of arterial collagen. And we have also demonstrated the suppression of intimal hyperplasia in animal experiments. We need to understand the PTDB dilatation mechanism to determine the optimum operation parameters. The prototype PTDB with diameter of 3mm was used in our experiments. The internal diameters of extracted fresh porcine carotid arteries at pre- and post- PTDB dilatation were measured. Balloon parameters were follows; pressure P=2atm, peak temperature in balloon T=60-80 °C, and heating duration t=4-30s. Morphological change in the media of dilated artery with PTDB were microscopically examined with Weigert staining. Elastic properties were carried out by stress-strain measurements with calculation of young's modulus. We found that PTDB dilatation provided the effect to prevent elastic recoil. We explained that the reason of this effect might be arrangement of micro- structure in the media, i.e., heat-denatured collagen fibers sustained the elastic recoil due to rubbery elastin fibers. The arterial elasticity was not significant different after PTDB dilatation. It was suggested that there could be no compliance mismatch after PTDB dilatation in physiological range. We found that a part of PTDB dilatation mechanism, in which the vascular wall structure played an important role. The optimum operation parameters for PTDB might be determined in consideration of collagen denaturation progress and arterial composition.

  15. Lattice BGK Simulations of the Blood Flow in Elastic Vessels

    Institute of Scientific and Technical Information of China (English)

    LU Xiao-Yang; YI Hou-Hui; CHEN Ji-Yao; FANG Hai-Ping

    2006-01-01

    @@ The lattice Boltzmann method is applied to study the flow in elastic blood vessels. The volume-flow rate increases considerably when the compliance constant of the blood vessel is below a critical value. There is a region of the compliance constant in which the average volume-flow rate is dramatically enhanced. A harmonic perturbation of the pressure does not change the behaviour of the average volume-flow rate while the harmonic wave attenuates very quickly along the tube when the resonant period is close to that of the input wave. The model, together with the simulation results, is expected to be helpful to understand the mechanism of the blood volume-flow rate related to the compliance constant of the blood vessel, especially on the dependence of the flux of human blood vessel under weather changes, which has medical significance.

  16. Influence of cataract surgery and blood pressure changes caused by sodium restriction on retinal vascular diameter

    Directory of Open Access Journals (Sweden)

    Takatoshi Tano

    2010-11-01

    Full Text Available Takatoshi Tano1, Yoshimune Hiratsuka2, Koichi Ono1, Akira Murakami11Department of Ophthalmology, Juntendo University School of Medicine, Tokyo; 2National Institute of Public Health, Tokyo, JapanPurpose: To investigate the impact of cataract surgery and blood pressure changes induced by one week of sodium restriction on retinal vascular diameter.Methods: Fundus photographs of 200 patients were obtained before and one week after cataract surgery. For one week after admission, 100 patients received sodium restriction and 100 patients (ie, the control group did not receive sodium restriction. The diameter of the retinal vessels and blood pressure were compared between the sodium restriction group and the control group. The vascular diameter was measured using an objective computer-based method.Results: Neither group had a significant change in the diameter of the retinal vessels after cataract surgery. Although there was no significant change in retinal arterial and venular diameter in the sodium restriction group, one-week sodium restriction significantly reduced mean blood pressure. However, multiple linear regression analyses indicated that an increase in retinal arteriolar diameter was significantly associated with diabetes, hyperlipidemia, and alcohol intake.Conclusion: Cataract surgery and blood pressure reduction induced by one week of sodium restriction resulted in no significant change in retinal arteriolar diameter.Keywords: cataract surgery, hypertension, retinal blood vessel diameter, retinal fundus camera, sodium restriction.

  17. Implantable blood pressure sensor for analyzing elasticity in arteries

    Science.gov (United States)

    Franco-Ayala, Marco; Martínez-Piñón, Fernando; Reyes-Barranca, Alfredo; Sánchez de la Peña, Salvador; Álvarez-Chavez, José A.

    2009-03-01

    MEMS technology could be an option for the development of a pressure sensor which allows the monitoring of several electronic signals in humans. In this work, a comparison is made between the typical elasticity curves of several arteries in the human body and the elasticity obtained for MEMS silicon microstructures such as membranes and cantilevers employing Finite Element analysis tools. The purpose is to identify which types of microstructures are mechanically compatible with human arteries. The goal is to integrate a blood pressure sensor which can be implanted in proximity with an artery. The expected benefits for this type of sensor are mainly to reduce the problems associated with the use of bulk devices through the day and during several days. Such a sensor could give precise blood pressure readings in a continuous or periodic form, i.e. information that is especially important for some critical cases of hypertension patients.

  18. Skin Blood Perfusion and Cellular Response to Insertion of Insulin Pen Needles With Different Diameters

    DEFF Research Database (Denmark)

    Præstmark, Kezia Ann; Stallknecht, Bente Merete; Bo Jensen, Casper

    2014-01-01

    Today most research on pen needle design revolves around pain perception statements through clinical trials, but these are both costly, timely, and require high sample sizes. The purpose of this study was to test if tissue damage, caused by different types of needles, can be assessed by evaluating...... skin blood perfusion response around needle insertion sites. Three common sized pen needles of 28G, 30G, and 32G as well as hooked 32G needles, were inserted into the neck skin of pigs and then removed. Laser Speckle Contrast Analysis was used to measure skin blood perfusion for 20 minutes after......, but there was a trend of an increased response with increasing needle diameter. Skin blood perfusion response to pen needle insertions rank according to needle diameter, and the tissue response caused by hooked 32G needles corresponds to that of 28G needles. The relation between needle diameter and trauma when...

  19. The Primary Study of the Construction of Small Diameter Tissue-engineered Blood Vessel

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    1 IntroductionToday, the blood vessel substitutes are in large demand for coronary and peripheral bypass procedures. Each year, more than 600,000 coronary artery bypass graft procedures are performed in the United States. There are some blood vessel substitutes including autografts, allografts and synthetic grafts that have been applied in vascular surgery in clinics. But their clinical implementations are prevented, especially for the <6mm in diameter grafts, because of their shortcomings such as inadequat...

  20. In situ tissue engineering of functional small-diameter blood vessels by host circulating cells only

    NARCIS (Netherlands)

    Talacua, Hanna; Smits, Anthal I P M; Muylaert, Dimitri E P; Van Rijswijk, Jan Willem; Vink, Aryan; Verhaar, Marianne C.; Driessen-Mol, Anita; Van Herwerden, Lex A.; Bouten, Carlijn V C; Kluin, Jolanda; Baaijens, Frank P T

    2015-01-01

    Inflammation is a natural phase of the wound healing response, which can be harnessed for the in situ tissue engineering of small-diameter blood vessels using instructive, bioresorbable synthetic grafts. This process is dependent on colonization of the graft by host circulating cells and subsequent

  1. In situ tissue engineering of functional small-diameter blood vessels by host circulating cells only

    NARCIS (Netherlands)

    Talacua, Hanna; Smits, Anthal I P M; Muylaert, Dimitri E P; Van Rijswijk, Jan Willem; Vink, Aryan; Verhaar, Marianne C.; Driessen-Mol, Anita; Van Herwerden, Lex A.; Bouten, Carlijn V C; Kluin, Jolanda; Baaijens, Frank P T

    2015-01-01

    Inflammation is a natural phase of the wound healing response, which can be harnessed for the in situ tissue engineering of small-diameter blood vessels using instructive, bioresorbable synthetic grafts. This process is dependent on colonization of the graft by host circulating cells and subsequent

  2. Retinal hemodynamic oxygen reactivity assessed by perfusion velocity, blood oximetry and vessel diameter measurements

    DEFF Research Database (Denmark)

    Klefter, Oliver Niels; Lauritsen, Anne Øberg; Larsen, Michael

    2015-01-01

    PURPOSE: To test the oxygen reactivity of a fundus photographic method of measuring macular perfusion velocity and to integrate macular perfusion velocities with measurements of retinal vessel diameters and blood oxygen saturation. METHODS: Sixteen eyes in 16 healthy volunteers were studied at two...... measurements may provide comprehensive information about retinal metabolism....

  3. The blood pressure-induced diameter response of retinal arterioles decreases with increasing diabetic maculopathy

    DEFF Research Database (Denmark)

    Frederiksen, Christian Alcaraz; Jeppesen, Peter; Knudsen, Søren Tang;

    2006-01-01

    were measured using the Retinal Vessel Analyzer (RVA, Imedos, Germany) before, during, and after an increase in the blood pressure induced by isometric exercise. Additionally, the retinal thickness was measured using optical coherence tomography scanning. RESULTS: The arterioles contracted during......BACKGROUND: The aim of the study was to compare the diameter response of retinal arterioles and retinal thickness in patients with different stages of diabetic maculopathy during an increase in the arterial blood pressure. METHODS: Four groups each consisting of 19 individuals were studied. Group...

  4. Ratio of spleen diameter to red blood cell distribution width: a novel indicator for celiac disease.

    Science.gov (United States)

    Balaban, Daniel Vasile; Popp, Alina; Lungu, Andrei Marian; Costache, Raluca Simona; Anca, Ioana Alina; Jinga, Mariana

    2015-04-01

    Celiac disease (CD) is currently considerably underdiagnosed, setting the need for developing tools to select patients with probability of CD, who warrant further testing. Red blood cell distribution width (RDW) has been shown in previous studies to be a sensitive predictor for CD, but it lacks specificity. Splenic hypotrophy is also noted frequently in celiac patients. Our aim was to evaluate if spleen diameter to RDW ratio can be used as an indicator for CD. We evaluated 15 newly diagnosed CD patients, 52 patients with inflammatory bowel disease, and 35 patients with irritable bowel syndrome (IBS). We evaluated the differences in spleen diameter, RDW, and their ratio among the four groups. Two-thirds of the CD patients had elevated RDW, compared to 9% in the IBS group. A small spleen was seen in 80% of the celiacs, compared to 21.9% in the ulcerative colitis group, 10% in the Crohn disease group, and 9% in the IBS group. A spleen diameter to RDW ratio under 6 had a sensitivity of 73.3% and specificity of 88.5% in predicting CD, with an AUROC of 0.737. Spleen diameter to RDW ratio is a simple, widely available score, which can be used to select adult patients with probability of CD.

  5. Association of body composition and blood pressure categories with retinal vessel diameters in primary school children.

    Science.gov (United States)

    Imhof, Katharina; Zahner, Lukas; Schmidt-Trucksäss, Arno; Hanssen, Henner

    2016-06-01

    Alterations in retinal vessel diameters have been shown to be predictive of cardiovascular risk in adults and children. The aim of our study was to examine the association of body composition and blood pressure (BP) categories with retinal vessel diameters in school children. We examined anthropometric parameters, BP and retinal arteriolar (CRAE) and venular (CRVE) diameters as well as the arteriolar-to-venular diameter ratio (AVR) in 391 children (age: 7.3, s.d. 0.4). Differences between the lowest and highest BP quartiles indicated that higher systolic and diastolic BP were associated with narrower CRAE (P<0.001 for both). Children in the highest weight quartile had narrower CRAE compared with the lowest quartile (P=0.05). In the regression analysis, systolic and diastolic BP were associated with arteriolar narrowing (-0.4 measuring units (mu) per mm Hg, 95% confidence interval: [-0.6; -0.3] and -0.6 mu per mm Hg [-0.7; -0.4], respectively; P<0.001 for both). An independent association was found for diastolic BP only. Compared with normotensives (NT; 74.4% of cohort), arteriolar narrowing was already seen in children categorized as pre-hypertensive (PHT) (11.5% of cohort), which was similar to HT children (14.1% of cohort) (NT: mean 207.2 [205.6; 208.7] mu; PHT: 201.7 [197.8; 205.7] mu; HT: 199.7 [196.2; 203.3] mu; P=0.01 for PHT vs. NT and P<0.001 for HT vs. NT in systolic BP). Our results suggest that systolic and diastolic BP are main determinants of retinal arteriolar diameters; and therefore, microvascular health in young children. Pre-hypertension seems to be associated with retinal microvascular alterations early in life.

  6. Elasticity

    CERN Document Server

    Soutas-Little, Robert William

    2010-01-01

    According to the author, elasticity may be viewed in many ways. For some, it is a dusty, classical subject . . . to others it is the paradise of mathematics."" But, he concludes, the subject of elasticity is really ""an entity itself,"" a unified subject deserving comprehensive treatment. He gives elasticity that full treatment in this valuable and instructive text. In his preface, Soutas-Little offers a brief survey of the development of the theory of elasticity, the major mathematical formulation of which was developed in the 19th century after the first concept was proposed by Robert Hooke

  7. Vascular tissue engineering of small-diameter blood vessels: reviewing the electrospinning approach.

    Science.gov (United States)

    Ercolani, Enrico; Del Gaudio, Costantino; Bianco, Alessandra

    2015-08-01

    Vascular tissue engineering is a relevant research field aimed at elaborating and proposing innovative solutions to overcome the drawbacks related to the use of conventional blood vessel substitutes, especially referring to small-diameter grafts. For this aim, electrospinning can be regarded as a valuable technique to produce novel scaffolds with several functional characteristics that can be usefully tailored for the application discussed here. The reproduction of the natural extracellular matrix obtained by processing bioresorbable polymers, either functionalized or not, is driving the biomedical research towards technical solutions that can lead to an actual therapeutic improvement. In this context, this paper reviews those studies focused on the selection of suitable biomaterials for vascular applications, their microstructure, the cell response to polymeric fibres and the strategies considered so far to modify and therefore enhance the performance of final electrospun scaffolds.

  8. Electrospun Polycaprolactone Scaffolds for Small-Diameter Tissue Engineered Blood Vessels

    Science.gov (United States)

    Lee, Carol Hsiu-Yueh

    Cardiovascular disease is the leading cause of death in the United States with many patients requiring coronary artery bypass grafting. The current standard is using autografts such as the saphenous vein or intimal mammary artery, however creating a synthetic graft could eliminate this painful and inconvenient procedure. Large diameter grafts have long been established with materials such as DacronRTM and TeflonRTM, however these materials have not proved successful in small-diameter (biodegradable polymer (polycaprolactone) we utilize our expertise in electrospinning and femtosecond laser ablation to create a novel tri-layered tissue engineered blood vessel containing microchannels. The benefits of creating a tri-layer is to mimic native arteries that contain an endothelium to prevent thrombosis in the inner layer, aligned smooth muscle cells in the middle to control vasodilation and constriction, and a mechanically robust outer layer. The following work evaluates the mechanical properties of such a graft (tensile, fatigue, burst pressure, and suture retention strength), the ability to rapidly align cells in laser ablated microchannels in PCL scaffolds, and the biological integration (co-culture of endothelial and smooth muscle cells) with electrospun PCL scaffolds. The conclusions from this work establish that the electrospun tri-layers provide adequate mechanical strength as a tissue engineered blood vessel, that laser ablated microchannels are able to contain the smooth muscle cells, and that cells are able to adhere to PCL fibers. However, future work includes adjusting microchannel dimensions to properly align smooth muscle cells along with perfect co-cultures of endothelial and smooth muscle cells on the electrospun tri-layer.

  9. Backward elastic light scattering of malaria infected red blood cells

    Science.gov (United States)

    Lee, Seungjun; Lu, Wei

    2011-08-01

    We investigated the backward light scattering pattern of healthy and malaria (Plasmodium falciparum) parasitized red blood cells. The spectrum could clearly distinguish between predominant ring stage infected blood cells and healthy blood cells. Further, we found that infected samples mixed with different stages of P. falciparum showed different signals, suggesting that even variance in parasite stages could also be detected by the spectrum. These results together with the backward scattering technique suggest the potential of non-invasive diagnosis of malaria through light scattering of blood cells near the surface of human body, such as using eyes or skin surface.

  10. Effect of Elastic Constitutive Laws on the Deformation of Two-dimensional Red Blood Cell

    Institute of Scientific and Technical Information of China (English)

    GONG Zhao-xin; LU Chuan-jing

    2009-01-01

    Deformation of two-dimensional red blood cell in linear shear flow is simulated using the immersed boundary method, in which the cell is modeled as a force source instead of a real body. The effect of three constitutive laws, i.e. Hookean, Neo-Hookean and Skalak elasticity, on the deformation is studied by simulating the cell movement in two linear shear flows. The results show that the effect of the constitutive laws gets more obvious as the shear rate increases. Both the aspect ratio and the inclination of the steady shapes get bigger, and the differences between the periods of the cell tank-treading motion become larger. For the same shear flow, the period with Hookean elasticity is less than the period with Neo-Hookean elasticity and bigger than the period with Skalak elasticity.

  11. [In vitro study of regulation of shear stress on antithrombogenic potentials of endothelialized polyurethane small diameter artificial blood vessel].

    Science.gov (United States)

    Yang, Zhen; Tao, Jun; Wang, Jiemei; Tu, Chang; Feng, Lianqiang; Pan, Shirong; Ma, Hong

    2008-06-01

    This study was designed to investigate the changes of prostaglandin I2 (PGI2) and nitric oxide (NO) secreted by endothelialized polyurethane small diameter artificial blood vessel. The peripheral blood mononuclear cells of healthy adult were separated and induced into endothelial progenitor cells (EPCs), which were identified by the methods of discrepancy microphage and fluorescent immunology labeling. After the induced cells being seeded on the polyurethane small-diameter artificial vessels, the endothelialized polyurethane small diameter artificial blood vessels were divided into four different experimental groups, including stationary group, low-flow shear stress group (5 dynes/cm2), medium-flow shearstress group (15 dynes/cm2), and high-flow shear stress group (25 dynes/cm2). Then, the levels of 6-ketoprostaglandin F1alpha (6-keto-PGF1alpha) and NO of different time were measured by enzyme-linked immunosorbent assay and nitrate reductase methods. The peripheral blood mononuclear cells differentiated into EPCs. They presented typical "spindie-shaped" appearance, and they were positively labeled by fluorescent acetylated-LDL, lectin, FLK-1 and vWF. Shear stress enhanced the production of NO and 6-keto-PGF1alpha by EPCs in a dose-dependent manner. Therefore, shear stress increases the secretion of NO and PGI2 by EPC, which suggests that shear stress can improve the antithrombogenic potentials of endothelialized polyurethane small diameter artificial blood vessel.

  12. Automatic real time evaluation of red blood cell elasticity by optical tweezers.

    Science.gov (United States)

    Moura, Diógenes S; Silva, Diego C N; Williams, Ajoke J; Bezerra, Marcos A C; Fontes, Adriana; de Araujo, Renato E

    2015-05-01

    Optical tweezers have been used to trap, manipulate, and measure individual cell properties. In this work, we show that the association of a computer controlled optical tweezers system with image processing techniques allows rapid and reproducible evaluation of cell deformability. In particular, the deformability of red blood cells (RBCs) plays a key role in the transport of oxygen through the blood microcirculation. The automatic measurement processes consisted of three steps: acquisition, segmentation of images, and measurement of the elasticity of the cells. An optical tweezers system was setup on an upright microscope equipped with a CCD camera and a motorized XYZ stage, computer controlled by a Labview platform. On the optical tweezers setup, the deformation of the captured RBC was obtained by moving the motorized stage. The automatic real-time homemade system was evaluated by measuring RBCs elasticity from normal donors and patients with sickle cell anemia. Approximately 150 erythrocytes were examined, and the elasticity values obtained by using the developed system were compared to the values measured by two experts. With the automatic system, there was a significant time reduction (60×) of the erythrocytes elasticity evaluation. Automated system can help to expand the applications of optical tweezers in hematology and hemotherapy.

  13. Electro-elastic modeling of a dielectric elastomer diaphragm for a prosthetic blood pump

    Science.gov (United States)

    Goulbourne, Nakhiah C.; Frecker, Mary I.; Mockensturm, Eric

    2004-07-01

    A dielectric elastomer diaphragm is to be designed for potential use in a prosthetic blood pump. Application of an electric field deforms the membrane such that it moves from an initially flat configuration to an inflated state. This motion creates positive displacement of blood from the cardiac chambers thus mimicking the pump-like behavior of the natural heart. A comprehensive large deformation model accounting for the combined dielectric and elastic effect has been formulated. This paper presents recent developments in the model to further incorporate the entire nonlinear range of material elastic behavior and to more accurately represent the applied electric field by keeping the voltage constant as the membrane thickness decreases. The updated model is used to calculate the effects of varying system parameters such as pressure, voltage, prestretch, material constants, and membrane geometry. Analytical results are obtained for biaxially stretched 3M VHB 4905 polyacrylate films.

  14. About a mechanism of the influence of shear stress for viscosity of the blood in vessels of small diameter

    Directory of Open Access Journals (Sweden)

    Лев Николаевич Катюхин

    2014-12-01

    Full Text Available It is proposed a physiological and experimentally confirmed explanation of Fåhraeus-Lindqvist-effect in capillaries using the profile analyses of osmotic deformability of red blood cells. It was shown the dose-dependent change of the erythrocytes deformability in the stage of isotropic spheres after forming artificial water pores (nystatin and occlusion (PbCl2 of available pores. The Sigma-effect reducing of hematocrit and viscosity in a shear flow of blood through the vessels of a small diameter was conditioned by the interchange of liquid phase between the erythrocyte and the plasma.

  15. Two-phase pulsatile flows through porous conical tubes of small diameters. Modelisation of the blood microcirculation.

    Science.gov (United States)

    Zeggwagh, G; Bellet, D

    1987-01-01

    A theoretical study concerning two-component fluid pulsating flow through porous conical ducts is presented. The model corresponds to blood flows through small diameter porous conical vessels. This approach is based on a finite difference method. The physical hypothesis used were based on findings from simultaneous visualization methods. The influence of geometrical, hydrodynamical and structural parameters is systematically examined and related to velocity profiles, hydrostatic pressure.

  16. Measurement of meningeal blood vessel diameter in vivo with a plug-in for ImageJ.

    Science.gov (United States)

    Fischer, Michael J M; Uchida, Sae; Messlinger, Karl

    2010-09-01

    Changes in blood vessel diameter can be measured manually, but this is time-consuming and often impractical. For automatic measurement commercial solutions are available, but the proprietary algorithms and their potential shortcomings are not known to the user. We present an approach with a CCD camera for image acquisition combined with free and open source ImageJ software for offline analysis. A subtraction image allows for the evaluation of the diameter changes throughout the field of view. A full width at half-maximum algorithm plug-in was written to measure the vessel diameter. For a given line across a vessel, the results of five measurements with parallel shifts throughout an image stack are copied to the clipboard. For validation of this method an established in vivo model was used, namely vascular changes in the rat dura mater, reflecting the activity of the afferent neurons. Vasoconstriction of the meningeal arterioles induced by local electrical stimulation of the dura was inhibited by intravenous administration of the adrenoceptor antagonist phentolamine and amplified by the CGRP receptor antagonist olcegepant. The described methods allow the user to quickly evaluate vessel diameter changes in the whole acquired field at any selected position.

  17. Simulation of blood flow in a small-diameter vascular graft model with a swirl (spiral) flow guider

    Institute of Scientific and Technical Information of China (English)

    Robert; GUIDOIN

    2008-01-01

    Small-diameter vascular grafts are in large demand for coronary and peripheral bypass procedures, but present products still fail in long-term clinical application. In the present communication, a new type of small-diameter graft with a swirl flow guider was proposed to improve graft patency rate. Flow pattern in the graft was simulated numerically and compared with that in a conventional graft. The numerical results revealed that the swirl flow guider could indeed make the blood flow rotate in the new graft. The swirling flow distal to the flow guider significantly altered the flow pattern in the new graft and the ve- locity profiles were re-distributed. Due to the swirling flow, the blood velocity near the vessel wall and wall shear rate were greatly enhanced. We believe that the increased blood velocity near the wall and the wall shear rate can impede the occurrence of acute thrombus formation and intimal hyperplasia, hence can improve the graft patency rate for long-term clinical use.

  18. [Ultrasonic study of deep-vein diameter and blood flow spectrum changes in full-term pregnant women].

    Science.gov (United States)

    Qiu, Yu-wen; Chen, Cui-hua; Wang, Li-ping; Sun, Gui-qin; Su, Gui-dong; Song, Tian-rong; Li, Jing; Li, Ying-jia; Wang, Chen; Zhong, Mei

    2009-01-01

    To explore the changes in lower limb deep vein diameters, blood flow velocity and blood biochemistry in full-term pregnant women for early diagnosis and treatment of prothrombotic state. One hundred and twenty-eight full-term pregnant women at high risk of thrombosis (Group A), 61 healthy full-term pregnant women (Group B), and 42 healthy non-pregnant women (Group C) underwent high-resolution color Doppler ultrasound (CDU) for examining the deep veins of the lower limbs. The hematological indexes such as D-D, PLT, HGB, HCT, TT, APTT, PT, and FbgC were also observed in these 3 groups. Compared to Group B, the women in group A showed significantly increased diameters of the common femoral veins (CFV) and left superficial femoral vein (SFV), HCT and DD, but with significantly decreased peak blood flow in the bilateral popliteal veins (POPV) (Pchanges in groups A and B (Ppregnant women are at higher risk of prothrombotic state than non-pregnant women, and the full-term pregnant women with the high risk factors for thrombosis are more likely to have prothrombotic state than healthy full-term pregnant women. CDU examination of the lower limb deep veins can be of value in the diagnosis of prothrombotic state.

  19. ANALYSIS OF OSCILLATORY BLOOD FLOW IN VARYING-AREA ELASTIC VESSEL

    Institute of Scientific and Technical Information of China (English)

    Gong Ke-qin; Sun Hui; Liu Zhao-rong

    2003-01-01

    In this paper, by solving the fundamental equations of periodically oscillatory blood flow, the distributions of pressure gradient and blood velocity in varying-area elastic vessel were obtained, and then the wall shear stress and its gradient were calculated. As an example, the pulsatile blood flow in human carotid was analyzed and the effects of vessel taper angle on the distribution of wall shear stress and its gradient were discussed in detail. Numercial results show that the wall shear stress will enlarge when the taper angle increases. Meantime, no matter whether the vessel is converging or diverging, with the increase of the absolute value of taper angle, the amplitude of wall shear stress gradient will enlarge significantly.

  20. Electrospun vascular scaffold for cellularized small diameter blood vessels: A preclinical large animal study.

    Science.gov (United States)

    Ju, Young Min; Ahn, Hyunhee; Arenas-Herrera, Juan; Kim, Cheil; Abolbashari, Mehran; Atala, Anthony; Yoo, James J; Lee, Sang Jin

    2017-09-01

    The strategy of vascular tissue engineering is to create a vascular substitute by combining autologous vascular cells with a tubular-shaped biodegradable scaffold. We have previously developed a novel electrospun bilayered vascular scaffold that provides proper biological and biomechanical properties as well as structural configuration. In this study, we investigated the clinical feasibility of a cellularized vascular scaffold in a preclinical large animal model. We fabricated the cellularized vascular construct with autologous endothelial progenitor cell (EPC)-derived endothelial cells (ECs) and smooth muscle cells (SMCs) followed by a pulsatile bioreactor preconditioning. This fully cellularized vascular construct was tested in a sheep carotid arterial interposition model. After preconditioning, confluent and mature EC and SMC layers in the scaffold were achieved. The cellularized constructs sustained the structural integrity with a high degree of graft patency without eliciting an inflammatory response over the course of the 6-month period in sheep. Moreover, the matured EC coverage on the lumen and a thick smooth muscle layer were formed at 6months after transplantation. We demonstrated that electrospun bilayered vascular scaffolds in conjunction with autologous vascular cells may be a clinically applicable alternative to traditional prosthetic vascular graft substitutes. This study demonstrates the utility of tissue engineering to provide platform technologies for rehabilitation of patients recovering from severe, devastating cardiovascular diseases. The long-term goal is to provide alternatives to vascular grafting using bioengineered blood vessels derived from an autologous cell source with a functionalized vascular scaffold. This novel bilayered vascular construct for engineering blood vessels is designed to offer "off-the-shelf" availability for clinical translation. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. The effect of complex exercise rehabilitation program on body composition, blood pressure, blood sugar, and vessel elasticity in elderly women with obesity

    Science.gov (United States)

    Lee, Eun-Ok; Lee, Kwon-Ho; Kozyreva, Olga

    2013-01-01

    The purpose of this study is to identify what kind of effects complex exercise rehabilitation program has on body composition of female, blood pressure, blood sugar, blood vessel elasticity and find more effective complex exercise program for elderly females. The subjects are selected 30 females applicants in exercise program in City of G and not restricted in mobility to perform the exercise without any particular disorders. Exercise program is a combination of aerobic and strength training with different ratio, for the first 6 months focused on strength training complex exercise, and for next 6 months focused on aerobic exercise. Except for strength training and aerobic exercise, durations for strength, rest, and wrapping-up are equal. The frequency of experiments is 90 min each, 2 times per a week. Body composition, blood pressure, and blood vessel elasticity are tested pre and post experiment to compare the effectiveness of both complex exercises. As results, in the complex exercise program focused on strength training, weight, percent body fat, fat mass, waist hip ratio, systolic blood pressure, and diastolic pressure increased. Blood vessel elasticity maintained its level or slightly decreased. In the complex exercise focused on aerobic exercise, weight, percent body fat, fat mass, waist hip ratio, systolic pressure, and diastolic pressure decreased. Blood vessel elasticity on left foot and right foot are slightly different. Therefore, aerobic exercise is more effective than strength training for old obese females. PMID:24409428

  2. Simulation of blood flow in a small-diameter vascular raft model with a swirl (spiral) flow guider

    Institute of Scientific and Technical Information of China (English)

    ZHANG ZhiGuo; FAN YuBo; DENG XiaoYan; WANG GuiXue; ZHANG He; Robert GUIDOIN

    2008-01-01

    Small-dlameter vascular grafts are in large demand for coronary and peripheral bypass procedures, but present products still fail in long-term clinical application. In the present communication, a new type of small-diameter graft with a swirl flow guider was proposed to improve graft patency rate. Flow pattern in the graft was simulated numerically and compared with that in a conventional graft. The numerical results revealed that the swirl flow guider couldindeed make the blood flow rotate in the new graft. The swirling flow distal to the flow guider significantly altered the flow pattern in the new graft and the ve-locity profiles were re-distributed. Due to the swirling flow, the blood velocity near the vessel wall and wall shear rate were greatly enhanced. We believe that the increased blood velocity near the wall and the wall shear rate can impede the occurrence of acute thrombus formation and intimal hyperplasia, hence can improve the graft patency rate for long-term clinical use.

  3. A theoretical computerized study for the electrical conductivity of arterial pulsatile blood flow by an elastic tube model.

    Science.gov (United States)

    Shen, Hua; Zhu, Yong; Qin, Kai-Rong

    2016-12-01

    The electrical conductivity of pulsatile blood flow in arteries is an important factor for the application of the electrical impedance measurement system in clinical settings. The electrical conductivity of pulsatile blood flow depends not only on blood-flow-induced red blood cell (RBC) orientation and deformation but also on artery wall motion. Numerous studies have investigated the conductivity of pulsatile blood based on a rigid tube model, in which the effects of wall motion on blood conductivity are not considered. In this study, integrating Ling and Atabek's local flow theory and Maxwell-Fricke theory, we develop an elastic tube model to explore the effects of wall motion as well as blood flow velocity on blood conductivity. The simulation results suggest that wall motion, rather than blood flow velocity, is the primary factor that affects the conductivity of flowing blood in arteries.

  4. Biomimetic control of vascular smooth muscle cell morphology and phenotype for functional tissue-engineered small-diameter blood vessels.

    Science.gov (United States)

    Chan-Park, Mary B; Shen, Jin Ye; Cao, Ye; Xiong, Yun; Liu, Yunxiao; Rayatpisheh, Shahrzad; Kang, Gavin Chun-Wei; Greisler, Howard P

    2009-03-15

    Small-diameter blood vessel substitutes are urgently needed for patients requiring replacements of their coronary and below-the-knee vessels and for better arteriovenous dialysis shunts. Circulatory diseases, especially those arising from atherosclerosis, are the predominant cause of mortality and morbidity in the developed world. Current therapies include the use of autologous vessels or synthetic materials as vessel replacements. The limited availability of healthy vessels for use as bypass grafts and the failure of purely synthetic materials in small-diameter sites necessitate the development of a biological substitute. Tissue engineering is such an approach and has achieved promising results, but reconstruction of a functional vascular tunica media, with circumferentially oriented contractile smooth muscle cells (SMCs) and extracellular matrix, appropriate mechanical properties, and vasoactivity has yet to be demonstrated. This review focuses on strategies to effect the switch of SMC phenotype from synthetic to contractile, which is regarded as crucial for the engineering of a functional vascular media. The synthetic SMC phenotype is desired initially for cell proliferation and tissue remodeling, but the contractile phenotype is then necessary for sufficient vasoactivity and inhibition of neointima formation. The factors governing the switch to a more contractile phenotype with in vitro culture are reviewed.

  5. Damage induced in red blood cells by infrared optical trapping: an evaluation based on elasticity measurements

    Science.gov (United States)

    de Oliveira, Marcos A. S.; Moura, Diógenes S.; Fontes, Adriana; de Araujo, Renato E.

    2016-07-01

    We evaluated the damage caused to optically trapped red blood cells (RBCs) after 1 or 2 min of exposure to near-infrared (NIR) laser beams at 785 or 1064 nm. Damage was quantified by measuring cell elasticity using an automatic, real-time, homemade, optical tweezer system. The measurements, performed on a significant number (hundreds) of cells, revealed an overall deformability decrease up to ˜104% after 2 min of light exposure, under 10 mW optical trapping for the 785-nm wavelength. Wavelength dependence of the optical damage is attributed to the light absorption by hemoglobin. The results provided evidence that RBCs have their biomechanical properties affected by NIR radiation. Our findings establish limits for laser applications with RBCs.

  6. Architecture of the subendothelial elastic fibers of small blood vessels and variations in vascular type and size.

    Science.gov (United States)

    Shinaoka, Akira; Momota, Ryusuke; Shiratsuchi, Eri; Kosaka, Mitsuko; Kumagishi, Kanae; Nakahara, Ryuichi; Naito, Ichiro; Ohtsuka, Aiji

    2013-04-01

    Most blood vessels contain elastin that provides the vessels with the resilience and flexibility necessary to control hemodynamics. Pathophysiological hemodynamic changes affect the remodeling of elastic components, but little is known about their structural properties. The present study was designed to elucidate, in detail, the three-dimensional (3D) architecture of delicate elastic fibers in small vessels, and to reveal their architectural pattern in a rat model. The fine vascular elastic components were observed by a newly developed scanning electron microscopy technique using a formic acid digestion with vascular casts. This method successfully visualized the 3D architecture of elastic fibers in small blood vessels, even arterioles and venules. The subendothelial elastic fibers in such small vessels assemble into a sheet of meshwork running longitudinally, while larger vessels have a higher density of mesh and thicker mesh fibers. The quantitative analysis revealed that arterioles had a wider range of mesh density than venules; the ratio of density to vessel size was higher than that in venules. The new method was useful for evaluating the subendothelial elastic fibers of small vessels and for demonstrating differences in the architecture of different types of vessels.

  7. Differential effects of androgens on coronary blood flow regulation and arteriolar diameter in intact and castrated swine

    Directory of Open Access Journals (Sweden)

    O’Connor Erin K

    2012-05-01

    Full Text Available Abstract Background Low endogenous testosterone levels have been shown to be a risk factor for the development of cardiovascular disease and cardiovascular benefits associated with testosterone replacement therapy are being advocated; however, the effects of endogenous testosterone levels on acute coronary vasomotor responses to androgen administration are not clear. The objective of this study was to compare the effects of acute androgen administration on in vivo coronary conductance and in vitro coronary microvascular diameter in intact and castrated male swine. Methods Pigs received intracoronary infusions of physiologic levels (1–100 nM of testosterone, the metabolite 5α-dihydrotestosterone, and the epimer epitestosterone while left anterior descending coronary blood flow and mean arterial pressure were continuously monitored. Following sacrifice, coronary arterioles were isolated, cannulated, and exposed to physiologic concentrations (1–100 nM of testosterone, 5α-dihydrotestosterone, and epitestosterone. To evaluate effects of the androgen receptor on acute androgen dilation responses, real-time PCR and immunohistochemistry for androgen receptor were performed on conduit and resistance coronary vessels. Results In vivo, testosterone and 5α-dihydrotestosterone produced greater increases in coronary conductance in the intact compared to the castrated males. In vitro, percent maximal dilation of microvessels was similar between intact and castrated males for testosterone and 5α-dihydrotestosterone. In both studies epitestosterone produced significant increases in conductance and microvessel diameter from baseline in the intact males. Androgen receptor mRNA expression and immunohistochemical staining were similar in intact and castrated males. Conclusions Acute coronary vascular responses to exogenous androgen administration are increased by endogenous testosterone, an effect unrelated to changes in androgen receptor expression.

  8. The use of BDNF to enhance the patency rate of small-diameter tissue-engineered blood vessels through stem cell homing mechanisms.

    Science.gov (United States)

    Zeng, Wen; Wen, Can; Wu, Yangxiao; Li, Li; Zhou, Zhenhua; Mi, Jianhong; Chen, Wen; Yang, Mingcan; Hou, Chunli; Sun, Jiansen; Zhu, Chuhong

    2012-01-01

    The patency rate of small-diameter tissue-engineered blood vessels is the determinant for their application in coronary artery bypass grafting. The coronary artery is innervated by vagus nerves. The origin of vagus nerves is rich in brain-derived neurotrophic factors (BDNF). We have investigated whether BDNF could improve the patency rate of small-diameter tissue-engineered blood vessels through promoting stem cell homing and paracrine activity. In vitro, we isolated early and late endothelial progenitor cells (EPCs) and found BDNF could promote single clone formation and paracrine function of EPCs, and could also induce the proliferation, migration and differentiation of late EPCs. BDNF could enhance the capturing of EPCs in parallel-plate flow chamber. Flow cytometric analysis and laser-scanning confocal microscope showed BDNF could enhance the mobilization and homing of C57BL/6 mouse EPCs after wire injury. Based on it, BDNF was coupled to the lumen surface of the blood vessel matrix material incubated with collagen through SPDP to construct BDNF-modified small-diameter tissue-engineered blood vessel. The blood vessel patency rate was significantly higher than that of control group 8 weeks after implantation in rats and the endothelialization level was superior to control. These results demonstrate that BDNF can effectively improve patency of small-diameter tissue-engineered blood vessels through stem cell homing and paracrine, and it is expected to play an important role in the construction of substitutes for coronary artery bypass grafting.

  9. Thigh muscle size and vascular function after blood flow-restricted elastic band training in older women

    Science.gov (United States)

    Yasuda, Tomohiro; Fukumura, Kazuya; Tomaru, Takanobu; Nakajima, Toshiaki

    2016-01-01

    We examined the effect of elastic band training with blood flow restriction (BFR) on thigh muscle size and vascular function in older women. Older women were divided into three groups: low-intensity elastic band BFR training (BFR-Tr, n = 10), middleto high-intensity elastic band training (MH-Tr, n = 10), and no training (Ctrl, n = 10) groups. BFR-Tr and MH-Tr groups performed squat and knee extension exercises using elastic band, 2 days/week for 12 weeks. During BFR-Tr exercise session, subjects wore pressure cuffs around the most proximal region of both thighs. The following measurements were taken before (pre) and 3-5 days after (post) the final training session: MRI-measured muscle cross-sectional area (CSA) at mid-thigh, maximum voluntary isometric contraction (MVIC) of knee extension, central systolic blood pressure (c-SBP), central-augmentation index (c-AIx), cardio-ankle vascular index testing (CAVI), ankle-brachial pressure index (ABI). Quadriceps muscle CSA (6.9%) and knee extension MVIC (13.7%) were increased (p muscle CSA as well as maximal muscle strength, but does not decrease vascular function in older women. PMID:27244884

  10. Blood group typing based on recording the elastic scattering of laser radiation using the method of digital imaging

    Energy Technology Data Exchange (ETDEWEB)

    Dolmashkin, A A; Dubrovskii, V A; Zabenkov, I V [V.I.Razumovsky Saratov State Medical University, Saratov (Russian Federation)

    2012-05-31

    The possibility is demonstrated to determine the human blood group by recording the scattering of laser radiation with the help of the digital imaging method. It is experimentally shown that the action of a standing ultrasound wave leads to acceleration of the agglutination reaction of red blood cells, to formation of larger immune complexes of red blood cells, and, as a consequence, to acceleration of their sedimentation. In the absence of agglutination of red blood cells the ultrasound does not enhance the relevant processes. This difference in the results of ultrasound action on the mixture of blood and serum allows a method of blood typing to be offered. Theoretical modelling of the technique of the practical blood typing, carried out on the basis of the elastic light scattering theory, agrees well with the experimental results, which made it possible to plan further improvement of the proposed method. The studies of specific features of sedimentation of red blood cells and their immune complexes were aimed at the optimisation of the sample preparation, i.e., at the search for such experimental conditions that provide the maximal resolution of the method and the device for registering the reaction of red blood cells agglutination. The results of the study may be used in designing the instrumentation for blood group assessment in humans.

  11. Anisotropic micro-sphere-based finite elasticity applied to blood vessel modelling

    Science.gov (United States)

    Alastrué, V.; Martínez, M. A.; Doblaré, M.; Menzel, A.

    2009-01-01

    A fully three-dimensional anisotropic elastic model for vascular tissue modelling is presented here. The underlying strain energy density function is assumed to additively decouple into volumetric and deviatoric contributions. A straightforward isotropic neo-Hooke-type law is used to model the deviatoric response of the ground substance, whereas a micro-structurally or rather micro-sphere-based approach will be employed to model the contribution and distribution of fibres within the biological tissue of interest. Anisotropy was introduced by means of the use of von Mises orientation distribution functions. Two different micro-mechanical approaches—a, say phenomenological, exponential ansatz, and a worm-like-chain-based formulation—are applied to the micro-fibres and illustratively compared. The passage from micro-structural contributions to the macroscopic response is obtained by a computational homogenisation scheme, namely numerical integration over the surface of the individual micro-spheres. The algorithmic treatment of this integration is discussed in detail for the anisotropic problem at hand, so that several cubatures of the micro-sphere are tested in order to optimise the accuracy at reasonable computational cost. Moreover, the introduced material parameters are identified from simple tension tests on human coronary arterial tissue for the two micro-mechanical models investigated. Both approaches are able to recapture the experimental data. Based on the identified sets of parameters, we first discuss a homogeneous deformation in simple shear to evaluate the models' response at the micro-structural level. Later on, an artery-like two-layered tube subjected to internal pressure is simulated by making use of a non-linear finite element setting. This enables to obtain the micro- and macroscopic responses in an inhomogeneous deformation problem, namely a blood vessel representative boundary value problem. The effect of residual stresses is additionally

  12. Permeability dependence study of the focused ultrasound-induced blood-brain barrier opening at distinct pressures and microbubble diameters using DCE-MRI.

    Science.gov (United States)

    Vlachos, Fotios; Tung, Yao-Sheng; Konofagou, Elisa

    2011-09-01

    Blood-brain barrier opening using focused ultrasound and microbubbles has been experimentally established as a noninvasive and localized brain drug delivery technique. In this study, the permeability of the opening is assessed in the murine hippocampus after the application of focused ultrasound at three different acoustic pressures and microbubble sizes. Using dynamic contrast-enhanced MRI, the transfer rates were estimated, yielding permeability maps and quantitative K(trans) values for a predefined region of interest. The volume of blood-brain barrier opening according to the K(trans) maps was proportional to both the pressure and the microbubble diameter. A K(trans) plateau of ∼0.05 min(-1) was reached at higher pressures (0.45 and 0.60 MPa) for the larger sized bubbles (4-5 and 6-8 μm), which was on the same order as the K(trans) of the epicranial muscle (no barrier). Smaller bubbles (1-2 μm) yielded significantly lower permeability values. A small percentage (7.5%) of mice showed signs of damage under histological examination, but no correlation with permeability was established. The assessment of the blood-brain barrier permeability properties and their dependence on both the pressure and the microbubble diameter suggests that K(trans) maps may constitute an in vivo tool for the quantification of the efficacy of the focused ultrasound-induced blood-brain barrier opening.

  13. Several results from numerical investigation of nonlinear waves connected to blood flow in an elastic tube of variable radius

    CERN Document Server

    Dimitrova, Zlatinka I

    2015-01-01

    We investigate flow of incompressible fluid in a cylindrical tube with elastic walls. The radius of the tube may change along its length. The discussed problem is connected to the blood flow in large human arteries and especially to nonlinear wave propagation due to the pulsations of the heart. The long-wave approximation for modeling of waves in blood is applied. The obtained model Korteweg-deVries equation possessing a variable coefficient is reduced to a nonlinear dynamical system of 3 first order differential equations. The low probability of arising of a solitary wave is shown. Periodic wave solutions of the model system of equations are studied and it is shown that the waves that are consequence of the irregular heart pulsations may be modeled by a sequence of parts of such periodic wave solutions.

  14. INTRAOCULAR PRESSURE, MEAN ARTERIAL BLOOD PRESSURE AND PUPILLARY DIAMETER IN RABBITS ( (Oryctolagus cuniculus SUBJECTED TO RETROBULBAR BLOCK WITH DIFFERENT ANESTHETIC PROTOCOLS

    Directory of Open Access Journals (Sweden)

    Renata Maria Monção da Silva

    2015-10-01

    Full Text Available The aim of this study was to evaluate four protocols of loco regional anesthesia for ophthalmic procedures that could provide safety and life support, in addition to maintain intraocular pressure stable, with eye centralization and eyelid akinesia. 20 New Zealand rabbits were used to perform local anesthesia by retrobulbar block with four protocols: 2% lidocaine with epinephrine, 2% lidocaine without epinephrine associated with tramadol, 1% ropivacaine and bupivacaine 0.5 %. Each animal received an anesthetic volume of 1 mL. All anesthetic protocols used promoted eyelid akinesia and centralization of the eye during the assessment period. The retrobulbar block with the proposed anesthetic protocols proved to be feasible and safe for the maintenance of intraocular pressure, invasive blood pressure and pupillary diameter and can be used in intraocular surgeries, respecting the time of action of each anesthetic. All protocols showed an excellent blockage action but bupivacaine promoted the highest pupil diameter compared to the other drugs tested.

  15. [The rapid analysis of polychlorinated quaterphenyls in blood using different diameter capillary column with the high-resolution gas chromatograph high-resolution mass spectrometer].

    Science.gov (United States)

    Yasutake, Daisuke; Ashizuka, Yuki; Hori, Tsuguhide; Kurokawa, Youichi; Kajiwara, Jumboku; Hirata, Teruaki; Ishiguro, Yasuhisa; Iida, Takao; Uchi, Hiroshi; Furue, Masutaka

    2011-04-01

    The polychlorinated quaterphenyl (PCQ) concentrations in blood are important discriminative parameters in yusho patient. In this study, a rapid analytical method for PCQ using different diameter capillary column (rapid-Rtx65TG) with high-resolution gas chromatograph high-resolution mass spectrometer (HRGC/HRMS) instead of the gas chromatograph electron capture detector (ECD/GC) was developed. Using different diameter capillary columns, the analysis time of the HRGC/HRMS was drastically shortened, and the detection sensitivity was improved. In the rapid-Rtx65TG column, a small-bore capillary column (length 1m, I.D. 0.1mm) was connected with the inlet side of the GC, and behind that column, a large-bore capillary column (length 15mm, I.D. 0.53mm) for octadecachloroquaterphenyl (ODCQ) analysis was connected. In the HRGC/HRMS measurement of ODCQ by the rapid-Rtx65TG column, the minimum limit of detection for the apparatus was 0.4 pg, and the minimum limit of determination for the blood was 0.008 ppb. On ECD/GC in the conventional method and HRGC/HRMS in this study, the PCQ concentration in blood including yusho patients and yusho suspected persons was almost equivalent.

  16. [Pulsatile flow model with elastic blood vessels for duplex ultrasound studies].

    Science.gov (United States)

    Petrick, J; Schlief, R; Zomack, M; Langholz, J; Urbank, A

    1992-12-01

    Using ultrasound duplex technique flow phenomena in patients' circulation can be examined. For the interpretation of these examinations it is necessary to have extensive knowledge on flow influencing parameters. This can be easily obtained from simplified flow models. This article describes the components of a flow model that allows examination of ultrasonic contrast media flowing through an artificial heart and vessel mimicking tubes. The artificial heart is the drive which pumps a water glycerol cellulose mixture through the circulation in a pulsatile manner. The shape of the ventricle, the compliance of the aorta, the viscosity of the flow medium and the wall elasticity of the examination vessel were taken into account. The attenuation caused by the surrounding tissue is simulated by a variable layer of castor oil. The flow model is suitable to produce flow profiles that are very similar to physiological profiles.

  17. Compliant model of a coupled sequential coronary arterial bypass graft: effects of vessel wall elasticity and non-Newtonian rheology on blood flow regime and hemodynamic parameters distribution.

    Science.gov (United States)

    Kabinejadian, Foad; Ghista, Dhanjoo N

    2012-09-01

    We have recently developed a novel design for coronary arterial bypass surgical grafting, consisting of coupled sequential side-to-side and end-to-side anastomoses. This design has been shown to have beneficial blood flow patterns and wall shear stress distributions which may improve the patency of the CABG, as compared to the conventional end-to-side anastomosis. In our preliminary computational simulation of blood flow of this coupled sequential anastomoses design, the graft and the artery were adopted to be rigid vessels and the blood was assumed to be a Newtonian fluid. Therefore, the present study has been carried out in order to (i) investigate the effects of wall compliance and non-Newtonian rheology on the local flow field and hemodynamic parameters distribution, and (ii) verify the advantages of the CABG coupled sequential anastomoses design over the conventional end-to-side configuration in a more realistic bio-mechanical condition. For this purpose, a two-way fluid-structure interaction analysis has been carried out. A finite volume method is applied to solve the three-dimensional, time-dependent, laminar flow of the incompressible, non-Newtonian fluid; the vessel wall is modeled as a linearly elastic, geometrically non-linear shell structure. In an iteratively coupled approach the transient shell equations and the governing fluid equations are solved numerically. The simulation results indicate a diameter variation ratio of up to 4% and 5% in the graft and the coronary artery, respectively. The velocity patterns and qualitative distribution of wall shear stress parameters in the distensible model do not change significantly compared to the rigid-wall model, despite quite large side-wall deformations in the anastomotic regions. However, less flow separation and reversed flow is observed in the distensible models. The wall compliance reduces the time-averaged wall shear stress up to 32% (on the heel of the conventional end-to-side model) and somewhat

  18. Association between uterine artery Doppler blood flow changes and arterial wall elasticity in pregnant women.

    Science.gov (United States)

    von Wowern, Emma; Andersson, Jakob; Skarping, Ida Dalene; Howie, Maria Teresa; Olofsson, Per

    2017-10-01

    Uterine artery (UtA) Doppler velocimetry changes and increased arterial stiffness are associated with preeclampsia. We aimed to investigate the relation between UtA velocimetry changes and arterial stiffness in pregnant women. Doppler velocimetry and photoplethysmographic digital pulse wave analysis (DPA) were performed in 173 pregnant women in the second or the third trimester, where UtA Doppler pulsatility index (PI), diastolic notching, and UtA score (UAS) combining notching and high PI were calculated. DPA stiffness parameters representing large arteries were ejection elasticity index (EEI) and b/a, small arteries dicrotic index (DI) and d/a, and global stiffness the aging index (AI). One hundred and thirty women had normal Doppler and 43 had diastolic notching, of whom nine had high PI. DI indicated increased stiffness in small arteries when notching was present (p = 0.044) and showed a significant but weak correlation to UAS (p = 0.025, tau 0.12). EEI and b/a indicated increased large artery stiffness (p ≤0.014), d/a small artery stiffness (p = 0.023), and AI a systemic stiffness (p = 0.040) when high PI. High UtA PI was associated with increased systemic arterial stiffness, whereas notching was related to increased stiffness in small arteries only. This indicates pathophysiological differences between the two Doppler parameters.

  19. Evaluation of blood pressure and aortic elasticity of offspring of diabetic Wistar rats who have consumed flaxseed oil during pregnancy and lactation.

    Science.gov (United States)

    Vicente, Gabriela Câmara; Correia-Santos, André Manoel; Chagas, Maurício Alves; Boaventura, Gilson Teles

    2017-04-01

    This study aimed to investigate whether maternal use of flaxseed oil has effects on blood pressure and aorta elastic fibre in female offspring of diabetic mothers. Diabetes was induced into the rats (n = 18) by a high-fat diet and streptozotocin. After diabetes confirmation, rats were mated, and after pregnancy was confirmed, they were allocated into three groups: control group (CG); high-fat group (HFG); and flaxseed oil group (FOG). At weaning, female offspring (n = 6/group) received standard chow diet and were euthanized at 100 days of life. The following blood pressure and the percentage of the aortic elastic fibre were analysed. HFG showed higher blood pressure, and the use of flaxseed oil avoided this condition in FOG (p < 0.001) and increased the percentage of the aortic elastic fibre (p < 0.022). Flaxseed oil reduced the damage caused by maternal hyperglycaemia, promoting normal blood pressure and elasticity of the aorta in female offspring.

  20. Effect of Chinese herbal medicine for calming Gan (肝) and suppressing hyperactive yang on arterial elasticity function and circadian rhythm of blood pressure in patients with essential hypertension.

    Science.gov (United States)

    Zhong, Guang-wei; Chen, Min-jing; Luo, Yan-hong; Xiang, Ling-li; Xie, Qi-ying; Li, Yun-hui; Zhang, Chen; Gao, Feng

    2011-06-01

    To observe the effect of Chinese herbal medicine for calming Gan (肝) and suppressing hyperactive yang (平肝潜阳, CGSHY) on arterial elasticity function and the circadian rhythm of blood pressure in patients with essential hypertension (EH). Adopting a parallel, randomized design, sixty-four patients with EH of stages I and II were randomly divided into two groups according to a random number table, with 32 in each group. The patients in the treatment group were treated with CGSHY and those in the control group were treated with Enalapril. All patients were given 24-h ambulatory blood pressure monitoring (ABPM) before and after a 12-week treatment. Trough/peak (T/P) ratios of systolic and diastolic blood pressure (SBP & DBP) of each group were calculated. The circadian rhythm of their blood pressure was observed at the same time. The changes in elasticity of the carotid artery in the patients, including stiffness parameter (β), pressure-strain elastic modulus (Ep), arterial compliance (AC), augmentation index (AI), and pulse wave velocity (PVWβ) were determined by the echo-tracking technique before and after a 12-week treatment. In the meantime, their levels of nitric oxide (NO) and endothelin-1 (ET-1) were measured respectively. After treatment, all parameters in the 24-h ABPM and the elasticity of the carotid artery (β, Ep, AC and PVWβ) were markedly improved, the level of NO was increased, and ET-1 was decreased in both groups as compared with values before treatment (Pmonitoring and the elasticity of the carotid artery, the recovery of blood pressure circadian rhythm, and the therapeutic effect of antihypertension in EH patients between the two groups (P>0.05). Chinese herbal medicine for CGSHY may lower the blood pressure smoothly and recover the circadian rhythm of blood pressure in EH patients. They may also improve the carotid elasticity of EH patients similar to that of Enalapril. The mechanism of action of Chinese herbs on EH might be related to

  1. The blood pressure variability, arterial elasticity and humoral factors in subjects with family history of hypertension.

    Science.gov (United States)

    Rafidah, H M; Azizi, A; Suhaimi, H; Noriah, M N

    2008-03-01

    Normotensive subjects with family history of hypertension (FHT) have been reported to have increased left ventricular mass index and reduced ventricular compliance. Of interest is whether blood pressure variability (BPV), which has been associated with target organ damage, is then part of this complex inherited syndrome? The objectives of this study are to determine whether there are any significant differences in BPV, arterial compliance and humoral factors in subjects with FHT as compared to controls. Thirty-five subjects with self reported FHT and 35 matched controls underwent 24 hour BP monitoring (BR-102, Schiller Inc. Germany). Arterial compliance was measured using systolic pulse wave tonometry (HDI/Pulsewave Cardiovascular Profiling Instrument, Hypertension Diagnostic Inc. USA). None of the subjects were hypertensive or diabetic. Out of these numbers, 25 subjects with FHT and 26 controls had measurements of plasma catecholamines, plasma renin and serum aldosterone. Catecholamines were assayed with high performance liquid chromatography, while both renin and aldosterone measurements were by radioimmunoassay. Subjects with FHT have higher night time BPV. There was no significant difference in arterial compliances between both groups. There were increased level of norepinephrine (NE) in subjects with FHT but epinephrine (E), renin and aldosterone levels were similar in both groups. There were no correlations between NE and BPV but E was negatively associated with daytime and mean arterial systolic BPV. In conclusion subjects with FHT demonstrated a higher night time BPV and NE level as compared to controls.

  2. Experimental Study on Tissue Engineered Small-Diameter Blood Vessel Walls Using Adipose Derived Stem Cells%应用脂肪干细胞构建组织工程化小口径血管平滑肌层的实验研究

    Institute of Scientific and Technical Information of China (English)

    王琛; 郭芳芳; 张昀; 巩伦礼; 崔磊

    2012-01-01

    Objective To investigate the feasibility of constructing tissue engineered blood vessel walls in bioreactor using adipose derived stem cells. Methods Adipose derived stem cells (ADSCs) were obtained from fresh human lipoaspirates, and under the induction of TGF-31 and BMP4, hADSCs were differentiated into smooth muscle cells, and then the differentiated hADSCs were collected and seeded onto PGA mesh to form cell-PGA constructs. Thereafter, the cell/PGA constructs were cultivated in a bioreactor with the pulsatile radial stress (pulse rate: 75/min, radical distension <5%) for 8 weeks. New small diameter blood vessel walls was formed, the constructs were examined histologically and biomechanically and compared with normal blood vessels. Results With induction of TGF-β1 and BMP4 together, hADSCs acquired a SMC morphology, and grew in a "hill and valley" pattern similar to what was observed in primary isolated hUASMCs, with the expression of smooth muscle-specific contractile proteins including α- SMA, SM22α, calponin, and SM-MHC. An elastic small diameter vessel wall (4 mm in diameter) with improved biomechanical strength and well-organized collagenous fibers were engineered by in vitro culture of SMC -differentiated hADSCs on the PGA scaffold in a blood vessel bioreactor. Conclusion hADSCs can serve as a new cell source for SMCs in blood vessel engineering, and an elastic small diameter vessel wall could be engineered in a bioreactor. It is a promising candidate for treating cardiovascular diseases and for blood vessel engineering purposes.%目的 探索利用脂肪干细胞在生物反应器内构建组织工程血管平滑肌层的可行性.方法 用抽吸的脂肪获取脂肪干细胞,在生长因子TGF-β1和BMP4作用下诱导成平滑肌细胞,然后将诱导的平滑肌细胞接种于PGA上,将细胞-材料复合物置于生物反应器内进行培养,在模拟胚胎发育血流动力学的刺激下(搏动频率:75次/分;扩展量<5%),构建小口径

  3. In vitro evaluation of elastic multiblock co-polymers as a scaffold material for reconstruction of blood vessels.

    Science.gov (United States)

    Tzoneva, Rumiana; Weckwerth, Claudia; Seifert, Barbara; Behl, Marc; Heuchel, Matthias; Tsoneva, Iana; Lendlein, Andreas

    2011-01-01

    There is a need to create cell- and histocompatible implant materials, which might temporarily replace the mechanical function of a native tissue for regenerative therapies. To match the elastic behavior of the native tissue two different multiblock co-polymers were investigated: PDC, consisting of poly(p-dioxanone) (PPDO)/poly(ε-caprolactone) (PCL), and PDD, based on PPDO/poly((adipinate-alt-1,4-butanediol)-co-(adipinate-alt-ethylene glycol)-co-adipinate-alt-diethylene glycol) (Diorez). PDC is capable of a shapememory effect. Both multiblock co-polymers show an improved elasticity compared to materials applied in established vascular prosthesis. PDD is softer than PDC at 20°C, while PDC maintains its elasticity at 37°C. Thermodynamic characteristics indicate a more polar surface of PDD. Low cell adhesion was found on surfaces with low molar free energy of hysteresis (ΔG) derived from contact angle measurements in wetting and dewetting mode and high cell adhesion on high-ΔG surfaces. An increasing content of PCL in PDC improved cell adhesion and spreading of human umbilical vein endothelial cells. The prothrombotic potential of PDD is higher than PDC. Finally, it is concluded that PDC is a promising material for vascular tissue engineering because of its improved elastic properties, as well as balanced prothrombotic and anti-thrombotic properties with endothelial cells.

  4. [The biological reaction of inflammation, methylglyoxal of blood plasma, functional and structural alterations in elastic type arteries at the early stage of hypertension disease].

    Science.gov (United States)

    Titov, V N; Dmitriev, V A; Oshchepkov, E V; Balakhonova, T V; Tripoten', M I; Shiriaeva, Iu K

    2012-08-01

    The article deals with studying of the relationship between biologic reaction of inflammation with glycosylation reaction and content of methylglyoxal in blood serum. The positive correlation between pulse wave velocity and content of methylglyoxal, C-reactive protein in intercellular medium and malleolar brachial index value was established. This data matches the experimental results concerning involvement of biological reaction of inflammation into structural changes of elastic type arteries under hypertension disease, formation of arteries' rigidity and increase of pulse wave velocity. The arterial blood pressure is a biological reaction of hydrodynamic pressure which is used in vivo by several biological functions: biological function of homeostasis, function of endoecology, biological function of adaptation and function of locomotion. The biological reaction of hydrodynamic (hydraulic) pressure is a mode of compensation of derangement of several biological functions which results in the very high rate of hypertension disease in population. As a matter of fact, hypertension disease is a syndrome of lingering pathological compensation by higher arterial blood pressure of the biological functions derangements occurring in the distal section at the level of paracrine cenoses of cells. The arterial blood pressure is a kind of in vivo integral indicator of deranged metabolism. The essential hypertension disease pathogenically is a result of the derangement of three biological functions: biological function of homeostasis, biological function of trophology - nutrition (biological reaction of external feeding - exotrophia) and biological function of endoecology. In case of "littering" of intercellular medium in vivo with nonspecific endogenic flogogens a phylogenetically earlier activation of biological reactions of excretion, inflammation and hydrodynamic arterial blood pressure occur. In case of derangement of biological function of homeostasis, decreasing of

  5. Permeability dependence study of the focused ultrasound-induced blood-brain barrier opening at distinct pressures and microbubble diameters using DCE-MRI

    OpenAIRE

    Vlachos, Fotios; TUNG, YAO-SHENG; Konofagou, Elisa

    2011-01-01

    Blood-brain barrier (BBB) opening using focused ultrasound (FUS) and microbubbles has been experimentally established as a non-invasive and localized brain drug delivery technique. In this study, the permeability of the opening is assessed in the murine hippocampus after the application of FUS at three different acoustic pressures and microbubble sizes. Using DCE-MRI, the transfer rates were estimated, yielding permeability maps and quantitative Ktrans values for a predefined region of intere...

  6. Transient blood flow in elastic coronary arteries with varying degrees of stenosis and dilatations: CFD modelling and parametric study.

    Science.gov (United States)

    Wu, Jianhuang; Liu, Guiying; Huang, Wenhua; Ghista, Dhanjoo N; Wong, Kelvin K L

    2015-01-01

    In this paper, we have analysed pulsatile flow through partially occluded elastic arteries, to determine the haemodynamic parameters of wall shear stress (WSS), wall pressure gradient and pressure drops (ΔP), contributing to enhanced flow resistance and myocardial ischaemic regions which impair cardiac contractility and cause increased work load on the heart. In summary, it can be observed that stenoses in an artery significantly influence the haemodynamic parameters of wall shear stress and pressure drop in contrast to dilatations case. This deduces that stenosis plays a more critical role in plaque growth and vulnerability in contrast to dilatation, and should be the key element in cardiovascular pathology and diagnosis. Through quantitative analysis of WSS and ΔP, we have provided a clearer insight into the haemodynamics of atherosclerotic arteries. Determination of these parameters can be helpful to cardiologists, because it is directly implicated in the genesis and development of atherosclerosis.

  7. Systolic blood pressure response after high-intensity interval exercise is independently related to decreased small arterial elasticity in normotensive African American women.

    Science.gov (United States)

    Carter, Stephen J; Goldsby, TaShauna U; Fisher, Gordon; Plaisance, Eric P; Gower, Barbara A; Glasser, Stephen P; Hunter, Gary R

    2016-05-01

    Aerobic exercise transiently lowers blood pressure. However, limited research has concurrently evaluated blood pressure and small arterial elasticity (SAE), an index of endothelial function, among African American (AA) and European American (EA) women the morning after (i.e., ≈22 h later) acute bouts of moderate-intensity continuous (MIC) and high-intensity interval (HII) exercise matched for total work. Because of greater gradients of shear stress, it was hypothesized that HII exercise would elicit a greater reduction in systolic blood pressure (SBP) compared to MIC exercise. After baseline, 22 AA and EA women initiated aerobic exercise training 3 times/week. Beginning at week 8, three follow-up assessments were conducted over the next 8 weeks at random to measure resting blood pressure and SAE. In total all participants completed 16 weeks of training. Follow-up evaluations were made: (i) in the trained state (TS; 8-16 weeks of aerobic training); (ii) ≈22 h after an acute bout of MIC exercise; and (iii) ≈22 h after an acute bout of HII exercise. Among AAs, the acute bout of HII exercise incited a significant increase in SBP (mm Hg) (TS, 121 ± 14 versus HII, 128 ± 14; p = 0.01) whereas responses (TS, 116 ± 12 versus HII, 113 ± 9; p = 0.34) did not differ in EAs. After adjusting for race, changes in SAE were associated (partial r = -0.533; p = 0.01) with changes in SBP following HII exercise. These data demonstrate an acute, unaccustomed bout of HII exercise produces physiological perturbations resulting in a significant increase in SBP that are independently associated with decreased SAE among AA women, but not EA women.

  8. In 6- to 8-year-old children, hair cortisol is associated with body mass index and somatic complaints, but not with stress, health-related quality of life, blood pressure, retinal vessel diameters, and cardiorespiratory fitness.

    Science.gov (United States)

    Gerber, Markus; Endes, Katharina; Brand, Serge; Herrmann, Christian; Colledge, Flora; Donath, Lars; Faude, Oliver; Pühse, Uwe; Hanssen, Henner; Zahner, Lukas

    2017-02-01

    Hair cortisol measurement has become an increasingly accepted approach in endocrinology and biopsychology. However, while in adult research hair cortisol has been proposed as a relevant biomarker for chronic stress (and its adverse consequences), studies with children are scarce. Therefore, the goal of the present exploratory study was to examine the associations between hair cortisol concentrations (HCCs), stress, and a series of health-related outcomes in a sample of Swiss first grade schoolchildren. The sample consisted of 318 children (53% girls, Mage=7.26, SD=0.35). Hair strands were taken near the scalp from a posterior vertex position, and HCCs were tested for the first 3-cm hair segment. Parents provided information about their children's age, gender, parental education, children's stress (recent critical life events, daily hassles), health-related quality of life, and psychosomatic complaints. Body composition, blood pressure, retinal vessel diameters, and cardiorespiratory fitness were measured with established methods. In multiple regression analyses, higher HCCs were weakly associated with increased BMI in girls (β=0.22, pquality of life, blood pressure, retinal vessel diameters, and cardiorespiratory fitness. Although small significant relationships were found between HCCs, BMI and somatic complaints, the findings of this exploratory study challenge the view that HCCs can be used as a reliable biomarker of recent critical life events, daily hassles, health-related quality of life, and cardiovascular health indicators in non-clinical young children. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Diets rich in conjugated linoleic acid and vaccenic acid have no effect on blood pressure and isobaric arterial elasticity in healthy young men

    DEFF Research Database (Denmark)

    Raff, M.; Tholstrup, T.; Sejrsen, K.

    2006-01-01

    The objective of this study was to examine the effect on blood pressure (BP) and isobaric arterial elasticity (AE), as a measure of arterial health, of a commercial mixture of conjugated linoleic acids (CLA) and of milk fat produced through livestock feeding to have a high content of vaccenic acid...... of the test diets did not differ on any outcome variable: e.g., systolic- and diastolic blood pressure (SBP and DBP), pulse pressure (PP), isobaric arterial compliance (AC), distensibility (AD), or volume (AV). In conclusion, diets rich in milk fat and either CLA or VA have no effect on BP or AE indices...... (VA). Healthy young men (n = 60) with a BMI of 22.5 +/- 2 kg/m(2) (mean +/- SD) participated in this double-blind, randomized, 5-wk, parallel intervention study. The participants substituted 115 g of their daily fat intake with fat from 1 of 3 test diets: 1) CLA-diet rich in CLA (4.7 g/d of c9, t11...

  10. Biological and mechanical evaluation of the small-diameter tissue-engineered blood vessels matrix%小口径组织工程血管基质材料的生物学和力学评价

    Institute of Scientific and Technical Information of China (English)

    谭菊; 曾文; 周静婷; 李刚; 张晓彦; 朱楚洪

    2014-01-01

    Objective To develop a small-diameter tissue-engineered blood vessels which possesses normal blood vessels physiological structure, good biocompatibility, and mechanical properties. And it was evaluated by mechanical and biological of national standard of medi-cal transfusion material. Methods The bio-derived material were regarded as the ground substance, and it was evaluated by mechanical and biological of national standard after composite modification. Results The axial and radial tensile stress of the blood vessel was 23. 14 N and 36. 79 N respectively, and it was greater than the standard 7. 5N. The tensile rate of the axial and radial was 95. 19% and 80. 24% respec-tively, which were higher than the standard value 20%. The suture strength of the blood vessel was 13. 71 N, which was conform to the me-chanical requirement. Mainly used blood vessels or its extracts to detect the pH of the blood vessels is in the scope of control deionized water pH (7. 5 ± 1. 5);the hemolysis rate was 1. 3972% which was less than 5%;the whole blood coagulation time was 50% longer than the con-trol level, and there was no stimulation after intradermal injection. Conclusion With bio-derived material as the ground substance and com-positely modified, this kind od blood vessels is conform to the mechanical and biological of national standard, and it has the potential of clini-cal application which could play an important role in the replacement therapy of small-diameter vascular xenografts.%目的:研制一种具备正常血管的生理结构和良好的生物相容性,而且具有血管力学特性的小口径组织工程血管基质材料,并按医用输血材料的力学及生物学国家标准评价。方法以去细胞生物衍生材料作为基质,按照国家标准对其进行力学和生物学评价。结果血管的轴向、径向拉伸应力分别为23.14 N和36.79 N,均大于标准规定的7.5 N;拉伸率分别为95.19%和80.24%,大于标准规定的20%

  11. Interpreting stem diameter changes

    Science.gov (United States)

    Hölttä, T.; Sevanto, S.; Nikinmaa, E.

    2009-12-01

    Detecting phloem transport in stem diameter changes Teemu Hölttä1, Sanna Sevanto2, Eero Nikinmaa1 1Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland 2Department of Physics, P.O. Box 48, FIN-00014 University of Helsinki, Finland Introduction The volume of living cells and xylem conduits vary according to pressures they are subjected to. Our proposition is that the behavior of the inner bark diameter variation which cannot be explained by changes in xylem water status arise from changes in the osmotic concentration of the phloem and cambial growth. Materials and methods Simultaneous xylem and stem diameter measurements were conducted between June 28th to October 4th 2006 in Southern Finland on a 47-year old, 15 meter tall, Scots pine tree (DBH 15 cm) at heights of 1.5 and 10 meters. The difference between the measured inner bark diameter and the inner bark diameter predicted from xylem diameter change with a simple model (assuming there was no change in the osmotic concentration of the phloem) is hypothesized to give the changes in the osmotic concentration of the inner bark. The simple model calculates the radial water exchange between the xylem and phloem driven by the water potential changes in the xylem. Results and Discussion The major signal in the inner bark diameter was the transpiration rate as assumed, but also a signal arising from the change in the osmotic concentration (Fig 1a). The predicted osmotic concentration of the phloem typically increased during the afternoon due to the loading of photosynthesized sugars to the phloem. Inner bark osmotic concentration followed the photosynthesis rate with a 3 and 4 hour time-lag at the top and base, respectively (Fig 1b). The connection between photosynthesis and the predicted change in phloem osmotic concentration was stronger in the upper part of the tree compared to lower part. The changes in the predicted osmotic concentration were not similar every day, indicating that

  12. Biopolymer Elasticity

    CERN Document Server

    Sinha, S

    2003-01-01

    In recent years molecular elasticity has emerged as an active area of research: there are experiments that probe mechanical properties of single biomolecules such as DNA and Actin, with a view to understanding the role of elasticity of these polymers in biological processes such as transcription and protein-induced DNA bending. Single molecule elasticity has thus emerged as an area where there is a rich cross-fertilization of ideas between biologists, chemists and theoretical physicists. In this article we present a perspective on this field of research.

  13. Blood

    Science.gov (United States)

    ... Also, blood is either Rh-positive or Rh-negative. So if you have type A blood, it's either A positive or A negative. Which type you are is important if you need a blood transfusion. And your Rh factor could be important ...

  14. Elastic Beanstalk

    CERN Document Server

    Vliet, Jurg; Wel, Steven; Dowd, Dara

    2011-01-01

    While it's always been possible to run Java applications on Amazon EC2, Amazon's Elastic Beanstalk makes the process easier-especially if you understand how it works beneath the surface. This concise, hands-on book not only walks you through Beanstalk for deploying and managing web applications in the cloud, you'll also learn how to use this AWS tool in other phases of development. Ideal if you're a developer familiar with Java applications or AWS, Elastic Beanstalk provides step-by-step instructions and numerous code samples for building cloud applications on Beanstalk that can handle lots

  15. Rotational elasticity

    Science.gov (United States)

    Vassiliev, Dmitri

    2017-04-01

    We consider an infinite three-dimensional elastic continuum whose material points experience no displacements, only rotations. This framework is a special case of the Cosserat theory of elasticity. Rotations of material points are described mathematically by attaching to each geometric point an orthonormal basis that gives a field of orthonormal bases called the coframe. As the dynamical variables (unknowns) of our theory, we choose the coframe and a density. We write down the general dynamic variational functional for our rotational theory of elasticity, assuming our material to be physically linear but the kinematic model geometrically nonlinear. Allowing geometric nonlinearity is natural when dealing with rotations because rotations in dimension three are inherently nonlinear (rotations about different axes do not commute) and because there is no reason to exclude from our study large rotations such as full turns. The main result of the talk is an explicit construction of a class of time-dependent solutions that we call plane wave solutions; these are travelling waves of rotations. The existence of such explicit closed-form solutions is a non-trivial fact given that our system of Euler-Lagrange equations is highly nonlinear. We also consider a special case of our rotational theory of elasticity which in the stationary setting (harmonic time dependence and arbitrary dependence on spatial coordinates) turns out to be equivalent to a pair of massless Dirac equations. The talk is based on the paper [1]. [1] C.G.Boehmer, R.J.Downes and D.Vassiliev, Rotational elasticity, Quarterly Journal of Mechanics and Applied Mathematics, 2011, vol. 64, p. 415-439. The paper is a heavily revised version of preprint https://arxiv.org/abs/1008.3833

  16. Double diameter boring tool

    Science.gov (United States)

    Ashbaugh, Fred N.; Murry, Kenneth R.

    1988-12-27

    A boring tool and a method of operation are provided for boring two concentric holes of precision diameters and depths in a single operation. The boring tool includes an elongated tool body, a shank for attachment to a standard adjustable boring head which is used on a manual or numerical control milling machine and first and second diametrically opposed cutting edges formed for cutting in opposite directions. The diameter of the elongated tool body is substantially equal to the distance from the first cutting edge tip to the axis of rotation plus the distance from the second cutting edge tip to the axis of rotation. The axis of rotation of the tool is spaced from the tool centerline a distance substantially equal to one-half the distance from the second cutting edge tip to the axis of rotation minus one-half the distance from the first cutting edge tip to the axis of rotation. The method includes the step of inserting the boring tool into the boring head, adjusting the distance between the tool centerline and the tool axis of rotation as described above and boring the two concentric holes.

  17. Carotid intima-media thickness and elastic properties of aortas in normotensive children of hypertensive parents.

    Science.gov (United States)

    Yildirim, Ali; Kosger, Pelin; Ozdemir, Gokmen; Sahin, Fezan Mutlu; Ucar, Birsen; Kilic, Zubeyir

    2015-09-01

    A significant correlation between hypertension history and high blood pressure has been observed with regard to age, race and gender. Investigating carotid intima-media thickness and aortic stiffness prior to the development of hypertension in children of hypertensive parents enabled us to evaluate these patients for subclinical atherosclerosis. We compared carotid intima-media thickness, aortic strain, distensibility, stiffness indices and elastic modulus in 67 normotensive children whose parents had a diagnosis of essential hypertension and 39 normotensive children with no parental history of hypertension. Although there were no significant differences between the two groups in terms of systolic blood pressure, diastolic blood pressure, average blood pressure and pulse pressure (P>0.05), systolic blood pressures were higher among patients 15 years and older in the study group. No significant differences were noted between the control and study groups regarding interventricular septal thickness, left-ventricular posterior wall thickness, left-ventricular systolic and diastolic diameter and aortic annulus diameter (P>0.05). The left atrium diameter was larger in the study group compared with that in the control group, mainly because of the values of the 15-year-old and older children (P=0.01). The mean, maximum and minimum values of carotid intima-media thickness were significantly different in the study group compared with the control group among all age groups (Pchildren of hypertensive parents compared with the control group (P=0.014, P=0.001, respectively). Although there were no differences between the study and control groups regarding aortic strain, aortic distensibility, elastic modulus and stiffness indices (P>0.05), aortic distensibility was lower, and aortic stiffness indices were higher among children 15 years and older in the study group. An increase in the carotid intima-media thickness in all age groups and a decrease in aortic elastic properties in

  18. Small diameter carbon nanopipettes

    Science.gov (United States)

    Singhal, Riju; Bhattacharyya, Sayan; Orynbayeva, Zulfiya; Vitol, Elina; Friedman, Gary; Gogotsi, Yury

    2010-01-01

    Nanoscale multifunctional carbon probes facilitate cellular studies due to their small size, which makes it possible to interrogate organelles within living cells in a minimally invasive fashion. However, connecting nanotubes to macroscopic devices and constructing an integrated system for the purpose of fluid and electrical signal transfer is challenging, as is often the case with nanoscale components. We describe a non-catalytic chemical vapor deposition based method for batch fabrication of integrated multifunctional carbon nanopipettes (CNPs) with tip diameters much smaller (10-30 nm) than previously reported (200 nm and above) and approaching those observed for multiwalled carbon nanotubes. This eliminates the need for complicated attachment/assembly of nanotubes into nanofluidic devices. Variable tip geometries and structures were obtained by controlled deposition of carbon inside and outside quartz pipettes. We have shown that the capillary length and gas flow rate have a marked effect on the carbon deposition. This gives us a flexible protocol, useful for growing carbon layers of different thicknesses at selective locations on a glass pipette to yield a large variety of cellular probes in bulk quantities. The CNPs possess an open channel for fluid transfer with the carbon deposited inside at 875 °C behaving like an amorphous semiconductor. Vacuum annealing of the CNP tips at temperatures up to 2000 °C yields graphitic carbon structures with an increase in conductivity of two orders of magnitude. Penetration of the integrated carbon nanoprobes into cells was shown to produce minimal Ca2+ signals, fast recovery of basal Ca2+ levels and no adverse activation of the cellular metabolism during interrogation times as long as 0.5-1 h.

  19. Relationship between diameter of split Hopkinson pressure bar and minimum loading rate under rock failure

    Institute of Scientific and Technical Information of China (English)

    LI Xi-bing; HONG Liang; YIN Tu-bing; ZHOU Zi-long; YE Zhou-yuan

    2008-01-01

    In order to investigate the relationship between bar diameter and loading rate of the split Hopkinson pressure bar(SHPB) setup under the failure of rock specimen and realize the medium strain rate loading of specimen, new SHPB setups with different elastic bar's diameters of 22, 36, 50 and 75 mm were constructed. The tests were carried out on these setups at different loading rates, and the specimens had the same diameter of elastic bars and same ratio of length to diameter. The test results show that the larger the elastic bar's diameter is, the less the loading rate is needed to cause specimen failure, they show good power relationship, and that under the same strain rate loading, specimens are broken more seriously with larger diameter SHPB setup than with smaller one.

  20. Modular Small Diameter Vascular Grafts with Bioactive Functionalities.

    Directory of Open Access Journals (Sweden)

    Meik Neufurth

    Full Text Available We report the fabrication of a novel type of artificial small diameter blood vessels, termed biomimetic tissue-engineered blood vessels (bTEBV, with a modular composition. They are composed of a hydrogel scaffold consisting of two negatively charged natural polymers, alginate and a modified chitosan, N,O-carboxymethyl chitosan (N,O-CMC. Into this biologically inert scaffold two biofunctionally active biopolymers are embedded, inorganic polyphosphate (polyP and silica, as well as gelatin which exposes the cell recognition signal, Arg-Gly-Asp (RGD. These materials can be hardened by exposure to Ca(2+ through formation of Ca(2+ bridges between the polyanions, alginate, N,O-CMC, and polyP (alginate-Ca(2+-N,O-CMC-polyP. The bTEBV are formed by pressing the hydrogel through an extruder into a hardening solution, containing Ca(2+. In this universal scaffold of the bTEBV biomaterial, polycations such as poly(L-Lys, poly(D-Lys or a His/Gly-tagged RGD peptide (three RGD units were incorporated, which promote the adhesion of endothelial cells to the vessel surface. The mechanical properties of the biopolymer material (alginate-Ca(2+-N,O-CMC-polyP-silica revealed a hardness (elastic modulus of 475 kPa even after a short incubation period in CaCl2 solution. The material of the artificial vascular grafts (bTEBVs with an outer size 6 mm and 1.8 mm, and an inner diameter 4 mm and 0.8 mm, respectively turned out to be durable in 4-week pulsatile flow experiments at an alternating pressure between 25 and 100 mbar (18.7 and 75.0 mm Hg. The burst pressure of the larger (smaller vessels was 850 mbar (145 mbar. Incorporation of polycationic poly(L-Lys, poly(D-Lys, and especially the His/Gly-tagged RGD peptide, markedly increased the adhesion of human, umbilical vein/vascular endothelial cells, EA.HY926 cells, to the surface of the hydrogel. No significant effect of the polyP samples on the clotting of human plasma is measured. We propose that the metabolically

  1. Computational Elastic Knots

    KAUST Repository

    Zhao, Xin

    2013-05-01

    Elastic rods have been studied intensively since the 18th century. Even now the theory of elastic rods is still developing and enjoying popularity in computer graphics and physical-based simulation. Elastic rods also draw attention from architects. Architectural structures, NODUS, were constructed by elastic rods as a new method of form-finding. We study discrete models of elastic rods and NODUS structures. We also develop computational tools to find the equilibria of elastic rods and the shape of NODUS. Applications of elastic rods in forming torus knot and closing Bishop frame are included in this thesis.

  2. The changes of central blood pressure and artery elasticity in individuals with high-normal blood pressure%正常高值血压者的中心动脉压对动脉弹性功能的影响

    Institute of Scientific and Technical Information of China (English)

    王华伟; 金丹丹; 汪世军; 吴小庆; 耿伯春; 唐关敏

    2016-01-01

    Objective To evaluate the changes of central blood pressure and artery elasticity in individuals with high- normal blood pressure (HNBP). Methods A total of 138 subjects underwent health examination were divided into ideal blood pressure group (n=72) and HNBP group (n=66) according to blood pressure. The central systolic blood pressures (CSBP) was measured indirectly by Ormon- Colin non- invasive radial artery pulse wave measurement device, and carotid- femoral pulse wave velocity (cfPWV) were measured by Complior device. Regression analysis was performed to determine the relationship between CSBP and cfPWV. Results CSBP and cfPWV were significantly higher in HNBP group than in ideal blood pressure group (P<0.01). CSBP was positively related to cfPWV (r=0.53, P<0.01). Stepwise regression analysis showed that CSBP was the risk factor for cfPWV (β=0.449, P<0.01). Conclusion Central blood pressure increases with decrease of artery elasticity in individuals with normal- high blood pressure.%目的探讨正常高值血压者中心动脉压与动脉弹性的变化。方法选取在医院体检中心行健康体检者138例,根据血压分为理想血压组72例和正常高值血压组66例,采用Ormon- Colin公司的无创桡动脉脉波检测装置测量中心动脉收缩压(CSBP),应用Complior脉搏波速度测定仪测量颈股脉搏波传导速度(cfPWV)。采用回归分析方法比较CSBP与cfPWV的变化及两者的相关性。结果正常高值血压组中心动脉压和cfPWV均高于理想血压组(均P<0.05)。中心动脉压与cfPWV呈正相关(r=0.53,P<0.01)。逐步回归分析显示中心动脉压是cfPWV的主要影响因素(β=0.449,P<0.01)。结论正常高值血压者中心动脉压增高,动脉弹性下降。

  3. Effect of diameter and surface roughness on ultrasonic properties of GaAs nanowires

    Science.gov (United States)

    Dhawan, Punit Kumar; Wan, Meher; Verma, S. K.; Pandey, D. K.; Yadav, R. R.

    2015-02-01

    Second and third order elastic constants of GaAs Nanowires (NWs) are calculated using the many-body interaction potential model. The velocities of ultrasonic waves at different orientations of propagation with unique axis are evaluated using the second order elastic constants. The ultrasonic attenuation and thermal relaxation times of the single crystalline GaAs-NW are determined as a function of diameter and surface roughness by means of Mason theoretical approach using the thermal conductivity and higher order elastic constants. The diameter variation of ultrasonic attenuation and thermal relaxation exhibit second order polynomial function of diameter. It is also found that ultrasonic attenuation and thermal relaxation follow the exponential decay with the surface roughness for GaAs-NW due to reduction in thermal conductivity caused by dominance of surface asperities. Finally, the correlations among ultrasonic parameters, thermal conductivity, surface roughness, and diameter for GaAs-NWs are established leading towards potential applications.

  4. Development and evaluation of elastomeric hollow fiber membranes as small diameter vascular graft substitutes

    Energy Technology Data Exchange (ETDEWEB)

    Mercado-Pagán, Ángel E.; Kang, Yunqing [Department of Orthopedic Surgery, Stanford University, Stanford, CA (United States); Findlay, Michael W. [Department of Plastic and Reconstructive Surgery, Stanford University, Stanford, CA (United States); University of Melbourne Department of Surgery, Royal Melbourne Hospital, Parkville, VIC (Australia); Yang, Yunzhi, E-mail: ypyang@stanford.edu [Department of Orthopedic Surgery, Stanford University, Stanford, CA (United States); Department of Materials Science and Engineering, Stanford University, Stanford, CA (United States)

    2015-04-01

    Engineering of small diameter (< 6 mm) vascular grafts (SDVGs) for clinical use remains a significant challenge. Here, elastomeric polyester urethane (PEU)-based hollow fiber membranes (HFMs) are presented as an SDVG candidate to target the limitations of current technologies and improve tissue engineering designs. HFMs are fabricated by a simple phase inversion method. HFM dimensions are tailored through adjustments to fabrication parameters. The walls of HFMs are highly porous. The HFMs are very elastic, with moduli ranging from 1–4 MPa, strengths from 1–5 MPa, and max strains from 300–500%. Permeability of the HFMs varies from 0.5–3.5 × 10{sup −6} cm/s, while burst pressure varies from 25 to 35 psi. The suture retention forces of HFMs are in the range of 0.8 to 1.2 N. These properties match those of blood vessels. A slow degradation profile is observed for all HFMs, with 71 to 78% of the original mass remaining after 8 weeks, providing a suitable profile for potential cellular incorporation and tissue replacement. Both human endothelial cells and human mesenchymal stem cells proliferate well in the presence of HFMs up to 7 days. These results demonstrate a promising customizable PEU HFMs for small diameter vascular repair and tissue engineering applications. - Highlights: • Hollow fiber membranes (HFMs) were fabricated and evaluated. • HFM properties could be tailored through adjustments to fabrication parameters. • Properties could match or exceed those of blood vessels. • HFM showed excellent compatibility in vitro. • HFMs have the potential to be used for small diameter vascular grafts.

  5. A Simulation of Blood Cells in Branching Capillaries

    CERN Document Server

    Isfahani, Amir H G; Freund, Jonathan B

    2008-01-01

    The multi-cellular hydrodynamic interactions play a critical role in the phenomenology of blood flow in the microcirculation. A fast algorithm has been developed to simulate large numbers of cells modeled as elastic thin membranes. For red blood cells, which are the dominant component in blood, the membrane has strong resistance to surface dilatation but is flexible in bending. Our numerical method solves the boundary integral equations built upon Green's functions for Stokes flow in periodic domains. This fluid dynamics video is an example of the capabilities of this model in handling complex geometries with a multitude of different cells. The capillary branch geometries have been modeled based upon observed capillary networks. The diameter of the branches varies between 10-20 mum. A constant mean pressure gradient drives the flow. For the purpose of this fluid dynamics video, the red blood cells are initiated as biconcave discs and white blood cells and platelets are initiated as spheres and ellipsoids resp...

  6. 肾癌硬度与血流灌注关系的初步探讨%Preliminary study of correlation between elasticity and blood perfusion in renal carcinoma

    Institute of Scientific and Technical Information of China (English)

    魏淑萍; 李飞; 杨斌; 傅宁华; 雷丽; 朱世杰

    2012-01-01

    Objective To investigate the correlation between elasticity obtained with acoustic radiation force impulse(ARFI) and blood perfusion obtained with contrast enhanced ultrasound(CEUS) in renal carcinoma.Methods Tweenty-four patients with renal carcinoma confirmed by operation and pathology underwent ARFI and CEUS sequentially,got preliminary information of elasticity,size and border with virtual touch tissue imaging (VTI),shear wave velocity (SWV) of tumor and renal cortex at least 2centimeters from the tumor margin were measured with virtual touch tissue quantification (VTQ),and then the imaging characteristics were analyzed with time intensity curve (TIC).The elasticity obtained with ARFI were compared with the blood perfusion obtained with CEUS.Results Totally 24 cases included 18 renal cell carcinomas,3 papillary renal cell carcinomas,2 chromophobe cell renal carcinomas and 1 rena1collecting duct carcinoma.In VTI,18 appeared darker,4 appeared brighter,and 2 had the same brightness as renal cortex.The SWV of tumor and renal cortex were (2.47±0.61)m/s,(2.10±0.94) m/s,respectively,19 were stiffer than renal cortex (79.2%),among which 18 appeared hyper-enhancement and 1 appeared hypo-enhancement;5 were softer than renal cortex (20.8%),among which 2 appeared hyper-enhancement and 3 appeared hypo-enhancement in CEUS.Tumors with different elasticity had different enhancement,stiff cases appeared hyper-enhancement,soft cases appeared hypo-enhancement (P < 0.05).Conclusions There is correlation between elasticity obtained with ARFI and blood perfusion obtained with CEUS in renal carcinoma%目的 探讨声辐射力脉冲成像(ARFI)技术反映的肾癌硬度与超声造影反映的血流灌注之间的关系.方法 对经手术病理证实的24例肾癌患者术前先行ARFI检查,声触诊组织成像(VTI)技术初步判断肿瘤硬度、大小和边界,声触诊组织量化(VTQ)技术测量肿瘤及距肿瘤边缘至少2 cm的正常肾皮质的剪切波速

  7. Diameter of basalt columns derived from fracture mechanics bifurcation analysis.

    Science.gov (United States)

    Bahr, H-A; Hofmann, M; Weiss, H-J; Bahr, U; Fischer, G; Balke, H

    2009-05-01

    The diameter of columnar joints forming in cooling basalt and drying starch increases with decreasing growth rate. This observation can be reproduced with a linear-elastic three-dimensional fracture mechanics bifurcation analysis, which has been done for a periodic array of hexagonal columnar joints by considering a bifurcation mode compatible with observations on drying starch. In order to be applicable to basalt columns, the analysis has been carried out with simplified stationary temperature fields. The critical diameter differs from the one derived with a two-dimensional model by a mere factor of 1/2. By taking into account the latent heat released at the solidification front, the results agree fairly well with observed column diameters.

  8. Elastic characteristics of aorta in patients with epilepsy

    Directory of Open Access Journals (Sweden)

    Yılmaz Cingozbay

    2011-02-01

    Full Text Available Aim To investigate elastic characteristics of the aorta in patientswith epilepsy.Methods Seventy five patients with a diagnosis of epilepsy through clinical and EEG findings and age and sex matched, 50 healthy controls were included. Systolic and diastolic blood pressures plus systolic and diastolic diameter of the aortic root was measured. Aortic strain (AS and aortic distensibility (AD and aortic distensibility index (BSI were calculated. Results The average age of the epilepsy group was 23.8.8 ± 8.2 years, and of the control group it was 24.1± 6.2 years (p>0.05. AS and AD were lower in the epileptic group while the aortic stiffness index was higher (10.4± 4.2 vs 16.9±0.2, p: 0.001, for AS; 8.7± 4.0 vs 17.2±0.1, p: 0.001, for AD and 20.1±0.1 vs 3.5±1.2, p: 0.001 for BSI. Conclusion Elastic characteristics of the aorta change in epileptic patients, with a decrease of the distensibility of the aorta and an increaseof the stiffness. After this preliminary study, new controlledstudies are needed.

  9. Diameters of Triton and Pluto

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, D.; Cruikshank, D.P. (Hawaii Univ., Honolulu (USA). Inst. for Astronomy); Brown, R.H. (Hawaii Univ., Honolulu (USA). Dept. of Physics and Astronomy; Hawaii Univ., Honolulu (USA). Hawaii Inst. of Geophysics)

    1982-12-02

    Upper limits are reported to the thermal IR emission from Triton, the major satellite of Neptune, and Pluto, the outermost planet, that permit significant upper limits to be set on their diameters and also demonstrate that both are high albedo objects. These results exclude the possibility that Triton is the largest planetary satellite and are consistent with the small size of Pluto deduced from other data.

  10. Elastically Decoupling Dark Matter

    CERN Document Server

    Kuflik, Eric; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai

    2015-01-01

    We present a novel dark matter candidate, an Elastically Decoupling Relic (ELDER), which is a cold thermal relic whose present abundance is determined by the cross-section of its elastic scattering on Standard Model particles. The dark matter candidate is predicted to have a mass ranging from a few to a few hundred MeV, and an elastic scattering cross-section with electrons, photons and/or neutrinos in the $10^{-3}-1$ fb range.

  11. Elastically Decoupling Dark Matter.

    Science.gov (United States)

    Kuflik, Eric; Perelstein, Maxim; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai

    2016-06-03

    We present a novel dark matter candidate, an elastically decoupling relic, which is a cold thermal relic whose present abundance is determined by the cross section of its elastic scattering on standard model particles. The dark matter candidate is predicted to have a mass ranging from a few to a few hundred MeV, and an elastic scattering cross section with electrons, photons and/or neutrinos in the 10^{-3}-1  fb range.

  12. ElasticSearch cookbook

    CERN Document Server

    Paro, Alberto

    2013-01-01

    Written in an engaging, easy-to-follow style, the recipes will help you to extend the capabilities of ElasticSearch to manage your data effectively.If you are a developer who implements ElasticSearch in your web applications, manage data, or have decided to start using ElasticSearch, this book is ideal for you. This book assumes that you've got working knowledge of JSON and Java

  13. Sagittal Abdominal Diameter: Application in Clinical Practice

    Directory of Open Access Journals (Sweden)

    Thaís Da Silva-Ferreira

    2014-05-01

    Full Text Available Excess visceral fat is associated with cardiovascular risk factors. Sagittal abdominal diameter (SAD has recently been highlighted as an indicator of abdominal obesity, and also may be useful in predicting cardiovascular risk. The purpose of the present study was to review the scientific literature on the use of SAD in adult nutritional assessment. A search was conducted for scientific articles in the following electronic databases: SciELO , MEDLINE (PubMed and Virtual Health Library. SAD is more associated with abdominal fat (especially visceral, and with different cardiovascular risk factors, such as, insulin resistance, blood pressure, and serum lipoproteins than the traditional methods of estimating adiposity, such as body mass index and waist-to-hip ratio. SAD can also be used in association with other anthropometric measures. There are still no cut-off limits established to classify SAD as yet. SAD can be an alternative measure to estimate visceral adiposity. However, the few studies on this diameter, and the lack of consensus on the anatomical site to measure SAD, are obstacles to establish cut-off limits to classify it.

  14. The truth about laser fiber diameters.

    Science.gov (United States)

    Kronenberg, Peter; Traxer, Olivier

    2014-12-01

    To measure the various diameters of laser fibers from various manufacturers and compare them with the advertised diameter. Fourteen different unused laser fibers from 6 leading manufacturers with advertised diameters of 200, 270, 272, 273, 365, and 400 μm were measured by light microscopy. The outer diameter (including the fiber coating, cladding, and core), cladding diameter (including the cladding and the fiber core), and core diameter were measured. Industry representatives of the manufacturers were interviewed about the diameter of their fibers. For all fibers, the outer and cladding diameters differed significantly from the advertised diameter (P cladding, and core diameters of fibers with equivalent advertised diameters differed by up to 180, 100, and 78 μm, respectively. Some 200-μm fibers had larger outer diameters than the 270- to 273-μm fibers. All packaging material and all laser fibers lacked clear and precise fiber diameter information labels. Of 12 representatives interviewed, 8, 3, and 1 considered the advertised diameter to be the outer, the cladding, and the core diameter, respectively. Representatives within the same company frequently gave different answers. This study suggests that, at present, there is a lack of uniformity between laser fiber manufacturers, and most of the information conveyed to urologists regarding laser fiber diameter may be incorrect. Because fibers larger than the advertised laser fibers are known to influence key interventional parameters, this misinformation can have surgical repercussions. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Elastic limit of silicane.

    Science.gov (United States)

    Peng, Qing; De, Suvranu

    2014-10-21

    Silicane is a fully hydrogenated silicene-a counterpart of graphene-having promising applications in hydrogen storage with capacities larger than 6 wt%. Knowledge of its elastic limit is critical in its applications as well as tailoring its electronic properties by strain. Here we investigate the mechanical response of silicane to various strains using first-principles calculations based on density functional theory. We illustrate that non-linear elastic behavior is prominent in two-dimensional nanomaterials as opposed to bulk materials. The elastic limits defined by ultimate tensile strains are 0.22, 0.28, and 0.25 along armchair, zigzag, and biaxial directions, respectively, an increase of 29%, 33%, and 24% respectively in reference to silicene. The in-plane stiffness and Poisson ratio are reduced by a factor of 16% and 26%, respectively. However, hydrogenation/dehydrogenation has little effect on its ultimate tensile strengths. We obtained high order elastic constants for a rigorous continuum description of the nonlinear elastic response. The limitation of second, third, fourth, and fifth order elastic constants are in the strain range of 0.02, 0.08, and 0.13, and 0.21, respectively. The pressure effect on the second order elastic constants and Poisson's ratio were predicted from the third order elastic constants. Our results could provide a safe guide for promising applications and strain-engineering the functions and properties of silicane monolayers.

  16. ElasticSearch cookbook

    CERN Document Server

    Paro, Alberto

    2015-01-01

    If you are a developer who implements ElasticSearch in your web applications and want to sharpen your understanding of the core elements and applications, this is the book for you. It is assumed that you've got working knowledge of JSON and, if you want to extend ElasticSearch, of Java and related technologies.

  17. Numerical and Analytical Analysis of Elastic Rotor Natural Frequency

    Directory of Open Access Journals (Sweden)

    Adis J. Muminovic

    2014-11-01

    Full Text Available In this paper simulation model which enables quick analysis of elastic rotor natural frequency modes is developed using Matlab. This simulation model enables users to get dependency diagram of natural frequency in relation to diameter and length of the rotor,density of the material or modulus of elasticity. Testing of the model is done using numerical analysis in SolidWorks software.

  18. Clinical value of color Doppler ultrasound detection of blood flow parameters and vascular diameter in carot-id artery and vertebral artery%彩色多普勒超声检测颈动脉及椎动脉血流参数和血管内径的临床价值

    Institute of Scientific and Technical Information of China (English)

    刘天宇; 刘艳伟; 郑利; 礼宁; 李丽

    2014-01-01

    Objective To investigate the effect and clinical value of color Doppler ultrasound detection of blood flow parameters and vascular diameter in carotid artery and vertebral artery.Methods 150 healthcases were collected as the study objects.According to the age and gender differences, making a detailed classification, color Doppler ultrasound was used to detected the internal carotid artery, vertebral artery and the carotid artery.Results As age grows,the blood flow velocity decreases,and the pulsatility index( PI) and resistance index( RI) has no obvi-ous relation with age;There were positive correlation between the diameter of the carotid artery and vertebral artery and age( P<0.05) ,and the male population the diameter of the carotid artery was significantly wider than that of the female population(P<0.05),left vertebral artery diameter was significantly wider than that of the right side(P<0.05).Conclusion Color Doppler ultrasound detection can let us get detailed carotid and vertebral artery anatomy and blood supply of information,which is good to diagnosis cerebrovascular disease.%目的:探讨彩色多普勒超声检测颈动脉、椎动脉血流参数和血管内径的有效性及其临床价值。方法募集150例健康者作为研究对象,按年龄与性别的不同,做详细的分类,对其颈总动脉、颈内动脉及椎动脉行超声多普勒超声检测。结果(1)20~39岁人群颈动脉动脉收缩期流速为(64.18±12.51)cm/s,明显高于>39~59岁人群的(52.08±11.59)cm/s(t=4.996,P<0.05),而搏动指数(PI)与阻力指数(RI)则与年龄无明显的关系;(2)20~39岁人群颈总动脉内径平均为(6.11±0.66) mm,而>39~59岁人群为(6.59±0.71)mm,差异有统计学意义(t=-3.413,P<0.05),男性人群颈动脉内径明显宽于女性人群(t=2.829,P<0.05),左侧椎动脉内径明显宽于右侧(t=3.481,P<0.05

  19. Measurement of Elastic Modulus of Collagen Type I Single Fiber.

    Science.gov (United States)

    Dutov, Pavel; Antipova, Olga; Varma, Sameer; Orgel, Joseph P R O; Schieber, Jay D

    2016-01-01

    Collagen fibers are the main components of the extra cellular matrix and the primary contributors to the mechanical properties of tissues. Here we report a novel approach to measure the longitudinal component of the elastic moduli of biological fibers under conditions close to those found in vivo and apply it to type I collagen from rat tail tendon. This approach combines optical tweezers, atomic force microscopy, and exploits Euler-Bernoulli elasticity theory for data analysis. This approach also avoids drying for measurements or visualization, since samples are freshly extracted. Importantly, strains are kept below 0.5%, which appear consistent with the linear elastic regime. We find, surprisingly, that the longitudinal elastic modulus of type I collagen cannot be represented by a single quantity but rather is a distribution that is broader than the uncertainty of our experimental technique. The longitudinal component of the single-fiber elastic modulus is between 100 MPa and 360 MPa for samples extracted from different rats and/or different parts of a single tail. Variations are also observed in the fibril-bundle/fibril diameter with an average of 325±40 nm. Since bending forces depend on the diameter to the fourth power, this variation in diameter is important for estimating the range of elastic moduli. The remaining variations in the modulus may be due to differences in composition of the fibril-bundles, or the extent of the proteoglycans constituting fibril-bundles, or that some single fibrils may be of fibril-bundle size.

  20. Elastic scattering phenomenology

    Energy Technology Data Exchange (ETDEWEB)

    Mackintosh, R.S. [The Open University, School of Physical Sciences, Milton Keynes (United Kingdom)

    2017-04-15

    We argue that, in many situations, fits to elastic scattering data that were historically, and frequently still are, considered ''good'', are not justifiably so describable. Information about the dynamics of nucleon-nucleus and nucleus-nucleus scattering is lost when elastic scattering phenomenology is insufficiently ambitious. It is argued that in many situations, an alternative approach is appropriate for the phenomenology of nuclear elastic scattering of nucleons and other light nuclei. The approach affords an appropriate means of evaluating folding models, one that fully exploits available empirical data. It is particularly applicable for nucleons and other light ions. (orig.)

  1. Statistical mechanics of elasticity

    CERN Document Server

    Weiner, JH

    2012-01-01

    Advanced, self-contained treatment illustrates general principles and elastic behavior of solids. Topics include thermoelastic behavior of crystalline and polymeric solids, interatomic force laws, behavior of solids, and thermally activated processes. 1983 edition.

  2. Mastering ElasticSearch

    CERN Document Server

    Kuc, Rafal

    2013-01-01

    A practical tutorial that covers the difficult design, implementation, and management of search solutions.Mastering ElasticSearch is aimed at to intermediate users who want to extend their knowledge about ElasticSearch. The topics that are described in the book are detailed, but we assume that you already know the basics, like the query DSL or data indexing. Advanced users will also find this book useful, as the examples are getting deep into the internals where it is needed.

  3. Yielding elastic tethers stabilize robust cell adhesion.

    Directory of Open Access Journals (Sweden)

    Matt J Whitfield

    2014-12-01

    Full Text Available Many bacteria and eukaryotic cells express adhesive proteins at the end of tethers that elongate reversibly at constant or near constant force, which we refer to as yielding elasticity. Here we address the function of yielding elastic adhesive tethers with Escherichia coli bacteria as a model for cell adhesion, using a combination of experiments and simulations. The adhesive bond kinetics and tether elasticity was modeled in the simulations with realistic biophysical models that were fit to new and previously published single molecule force spectroscopy data. The simulations were validated by comparison to experiments measuring the adhesive behavior of E. coli in flowing fluid. Analysis of the simulations demonstrated that yielding elasticity is required for the bacteria to remain bound in high and variable flow conditions, because it allows the force to be distributed evenly between multiple bonds. In contrast, strain-hardening and linear elastic tethers concentrate force on the most vulnerable bonds, which leads to failure of the entire adhesive contact. Load distribution is especially important to noncovalent receptor-ligand bonds, because they become exponentially shorter lived at higher force above a critical force, even if they form catch bonds. The advantage of yielding is likely to extend to any blood cells or pathogens adhering in flow, or to any situation where bonds are stretched unequally due to surface roughness, unequal native bond lengths, or conditions that act to unzip the bonds.

  4. Nonlinear elastic waves in materials

    CERN Document Server

    Rushchitsky, Jeremiah J

    2014-01-01

    The main goal of the book is a coherent treatment of the theory of propagation in materials of nonlinearly elastic waves of displacements, which corresponds to one modern line of development of the nonlinear theory of elastic waves. The book is divided on five basic parts: the necessary information on waves and materials; the necessary information on nonlinear theory of elasticity and elastic materials; analysis of one-dimensional nonlinear elastic waves of displacement – longitudinal, vertically and horizontally polarized transverse plane nonlinear elastic waves of displacement; analysis of one-dimensional nonlinear elastic waves of displacement – cylindrical and torsional nonlinear elastic waves of displacement; analysis of two-dimensional nonlinear elastic waves of displacement – Rayleigh and Love nonlinear elastic surface waves. The book is addressed first of all to people working in solid mechanics – from the students at an advanced undergraduate and graduate level to the scientists, professional...

  5. ELASTIC LIPOSOME: DRUG DELIVERY ACROSS HUMAN SKIN

    Directory of Open Access Journals (Sweden)

    Vardhan Harsh

    2012-04-01

    Full Text Available Transdermal drug delivery is hardly an old technology, since 1800’s and the technology is no longer just adhesive patches. Due to recent advances in technology and the ability to apply the drug to the site of action without rupturing the skin membrane, transdermal route is becoming a widely accepted route of drug administration. Recently, various strategies have been used to augment the transdermal delivery of bioactives. Mainly, they include iontophoresis, electrophoresis, sonophoresis, chemical permeation enhancers, micro needles, and vesicular system. Among these strategies elastic liposomes appear promising. Elastic liposomes possess an infrastructure consisting of hydrophobic and hydrophilic moieties together and as a result can accommodate drug molecules with wide range of solubility. It is an ultra deformable vesicle, elastic in nature which can squeeze itself through a pore which is many times smaller than its size owing to its elasticity. They can deform and pass through narrow constriction (from 5 to 10 times less than their own diameter without measurable loss. This high deformability gives better penetration of intact vesicles. This system is much more efficient at delivering a low and high molecular weight drug to the skin in terms of quantity and depth. The article speaks specifically on various phenomenon associated with the properties of these vesicles and their transport mechanisms. It also throws light on the effectiveness of conventional and deformable vesicles as drug delivery systems as well as their possible mode of action as transdermal drug carriers.

  6. MWD tool for deep, small diameter boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Buytaert, J.P.R.; Duckworth, A.

    1992-03-17

    This patent describes an apparatus for measuring a drilling parameters while drilling a borehole in an earth formation, wherein the borehole includes a small diameter deep borehole portion and a large diameter upper borehole portion. It includes small diameter drillstring means for drilling the deep borehole portion; sensor means, disposed within the small diameter drillstring means, for measuring a drilling parameter characteristic of the deep portion of the borehole while drilling the deep portion of the borehole and for providing sensor output signals indicative of the measured parameter; an upper drillstring portion extending between the surface of the formation and the small diameter drillstring means, the upper drillstring portion including a large diameter drillstring portion; data transmission means disposed within the large diameter drillstring portion and responsive to the sensor output.

  7. Assessment of Serum ADMA Levels and Aortic Elastic Properties in Patients with Ankylosing Spondylitis

    Directory of Open Access Journals (Sweden)

    Hasan Kaya

    2013-08-01

    Full Text Available Introduction: Ankylosing spondylitis is a chronic inflammatory disease which may be associated with cardiovascular complications. The aim of the study was to investigate aortic elastic properties and serum asymetric dimethylarginine (ADMA levels in patients with ankylosing spondylitis without any cardiac involvement.Patients and Methods: Fifty-five ankylosing spondylitis patients and 30 age/gender matched healthy subjects were enrolled into this study. Fasting glucose, serum lipids, C-reactive protein (CRP, erythrocyte sedimentation rate (ESR and ADMA were studied. Aortic strain, distensibility and stiffness index were calculated from aortic diameters measured by transthoracic echocardiography and simultaneous blood pressure measurements.Results: ESR and CRP were higher in patients group. Serum ADMA levels were also higher in ankylosing spondylitis than in controls (0.76 ± 0.19 vs. 0.55 ± 0.12, p< 0.001. In subgroup analysis, ADMA was significantly lower in anti-TNF-alfa treatment group than conventional treatment group (0.68 ± 0.15 vs. 0.87 ± 0.18, p< 0.001. Mean aortic strain and distensibility were lower and stiffness index was higher in ankylosing spondylitis group than controls. No correlation between ADMA and aortic elastic properties was observed. In ankylosing spondylitis group, a negative significant correlation was found between duration of ankylosing spondylitis and aortic strain and distensibility.Conclusion: Our study suggest that patients with ankylosing spondylitis without cardiac involvement, aortic elasticity was impaired and ADMA levels were increased, while there was no significant correlation between aortic elastic properties and ADMA levels.

  8. Bands in the spectrum of a periodic elastic waveguide

    Science.gov (United States)

    Bakharev, F. L.; Taskinen, J.

    2017-10-01

    We study the spectral linear elasticity problem in an unbounded periodic waveguide, which consists of a sequence of identical bounded cells connected by thin ligaments of diameter of order h >0. The essential spectrum of the problem is known to have band-gap structure. We derive asymptotic formulas for the position of the spectral bands and gaps, as h → 0.

  9. The effect of arterial wall shear stress on the incremental elasticity of a conduit artery.

    Science.gov (United States)

    Kelly, R F; Snow, H M

    2011-05-01

    The purpose of this investigation was to determine the effects of flow mediated dilatation on arterial incremental elasticity (E(inc) ).   In four female anaesthetized pigs, the iliac artery and vein were connected by a shunt with a variable resistance which allowed blood flow and therefore shear stress to be regulated. E(inc) was calculated from simultaneous records of diameter and pressure throughout a minimum of four cardiac cycles. Passive increases in diameter (∼1-2%) throughout a cardiac cycle, brought about by pressure, resulted in a two- to threefold increase in E(inc) . In contrast, increases in shear stress caused active smooth muscle relaxation and a significant increase in diameter from 3.663 ± 0.215 mm to 4.488 ± 0.163 mm (mean ± SEM, P stress, the interaction between smooth muscle and collagen operates so as to maintain E(inc) relatively constant over much of the working range of dilatation. This is consistent with a model of the arterial wall in which collagen is recruited both by passive stretch, in response to an increase in pressure and therefore wall stress, and also by active contraction of smooth muscle. © 2011 The Authors. Acta Physiologica © 2011 Scandinavian Physiological Society.

  10. Elastic anisotropy of crystals

    Directory of Open Access Journals (Sweden)

    Christopher M. Kube

    2016-09-01

    Full Text Available An anisotropy index seeks to quantify how directionally dependent the properties of a system are. In this article, the focus is on quantifying the elastic anisotropy of crystalline materials. Previous elastic anisotropy indices are reviewed and their shortcomings discussed. A new scalar log-Euclidean anisotropy measure AL is proposed, which overcomes these deficiencies. It is based on a distance measure in a log-Euclidean space applied to fourth-rank elastic tensors. AL is an absolute measure of anisotropy where the limiting case of perfect isotropy yields zero. It is a universal measure of anisotropy applicable to all crystalline materials. Specific examples of strong anisotropy are highlighted. A supplementary material provides an anisotropy table giving the values of AL for 2,176 crystallite compounds.

  11. Elastic constants of calcite

    Science.gov (United States)

    Peselnick, L.; Robie, R.A.

    1962-01-01

    The recent measurements of the elastic constants of calcite by Reddy and Subrahmanyam (1960) disagree with the values obtained independently by Voigt (1910) and Bhimasenachar (1945). The present authors, using an ultrasonic pulse technique at 3 Mc and 25??C, determined the elastic constants of calcite using the exact equations governing the wave velocities in the single crystal. The results are C11=13.7, C33=8.11, C44=3.50, C12=4.82, C13=5.68, and C14=-2.00, in units of 1011 dyncm2. Independent checks of several of the elastic constants were made employing other directions and polarizations of the wave velocities. With the exception of C13, these values substantially agree with the data of Voigt and Bhimasenachar. ?? 1962 The American Institute of Physics.

  12. Elastic scattering of hadrons

    CERN Document Server

    Dremin, I M

    2012-01-01

    When colliding, the high energy hadrons can either produce new particles or scatter elastically without change of their quantum num- bers and other particles produced. Namely elastic scattering of hadrons is considered in this review paper. Even though the inelastic processes dominate at high energies, the elastic scattering constitutes the notice- able part of the total cross section ranging between 18 and 25% with some increase at higher energies. The scattering proceeds mostly at small angles and reveals peculiar dependences at larger angles disclos- ing the geometrical structure of the colliding particles and di?erent dynamical mechanisms. The fast decreasing Gaussian peak at small angles is followed by the exponential (Orear) regime with some shoul- ders and dips and then by the power-like decrease. Results of various theoretical approaches are compared with exper- imental data. Phenomenological models pretending to describe this process are reviewed. The unitarity condition requires the exponen- tial re...

  13. An elastic second skin

    Science.gov (United States)

    Yu, Betty; Kang, Soo-Young; Akthakul, Ariya; Ramadurai, Nithin; Pilkenton, Morgan; Patel, Alpesh; Nashat, Amir; Anderson, Daniel G.; Sakamoto, Fernanda H.; Gilchrest, Barbara A.; Anderson, R. Rox; Langer, Robert

    2016-08-01

    We report the synthesis and application of an elastic, wearable crosslinked polymer layer (XPL) that mimics the properties of normal, youthful skin. XPL is made of a tunable polysiloxane-based material that can be engineered with specific elasticity, contractility, adhesion, tensile strength and occlusivity. XPL can be topically applied, rapidly curing at the skin interface without the need for heat- or light-mediated activation. In a pilot human study, we examined the performance of a prototype XPL that has a tensile modulus matching normal skin responses at low strain (<40%), and that withstands elongations exceeding 250%, elastically recoiling with minimal strain-energy loss on repeated deformation. The application of XPL to the herniated lower eyelid fat pads of 12 subjects resulted in an average 2-grade decrease in herniation appearance in a 5-point severity scale. The XPL platform may offer advanced solutions to compromised skin barrier function, pharmaceutical delivery and wound dressings.

  14. Anisotropic elastic plates

    CERN Document Server

    Hwu, Chyanbin

    2010-01-01

    As structural elements, anisotropic elastic plates find wide applications in modern technology. The plates here are considered to be subjected to not only in plane load but also transverse load. In other words, both plane and plate bending problems as well as the stretching-bending coupling problems are all explained in this book. In addition to the introduction of the theory of anisotropic elasticity, several important subjects have are discussed in this book such as interfaces, cracks, holes, inclusions, contact problems, piezoelectric materials, thermoelastic problems and boundary element a

  15. Hybrid elastic solids

    KAUST Repository

    Lai, Yun

    2011-06-26

    Metamaterials can exhibit electromagnetic and elastic characteristics beyond those found in nature. In this work, we present a design of elastic metamaterial that exhibits multiple resonances in its building blocks. Band structure calculations show two negative dispersion bands, of which one supports only compressional waves and thereby blurs the distinction between a fluid and a solid over a finite frequency regime, whereas the other displays super anisotropy-in which compressional waves and shear waves can propagate only along different directions. Such unusual characteristics, well explained by the effective medium theory, have no comparable analogue in conventional solids and may lead to novel applications. © 2011 Macmillan Publishers Limited. All rights reserved.

  16. Mechanics of elastic composites

    CERN Document Server

    Cristescu, Nicolaie Dan; Soós, Eugen

    2003-01-01

    This is a comprehensive, reader-friendly treatment of the theory behind modern elastic composite materials. The treatment includes recently developed results and methods drawn from research papers published in Eastern Europe that until now were unavailable in many western countries. Among the book''s many notable features is the inclusion of more than 400 problems, many of which are solved at the end of the book. Mechanics of Elastic Composites is an outstanding textbook for graduate-level course work and a valuable reference for engineers and researchers. Developed over many years by leading

  17. ElasticSearch server

    CERN Document Server

    Rogozinski, Marek

    2014-01-01

    This book is a detailed, practical, hands-on guide packed with real-life scenarios and examples which will show you how to implement an ElasticSearch search engine on your own websites.If you are a web developer or a user who wants to learn more about ElasticSearch, then this is the book for you. You do not need to know anything about ElastiSeach, Java, or Apache Lucene in order to use this book, though basic knowledge about databases and queries is required.

  18. Seismic fragility test of a 6-inch diameter pipe system

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W. P.; Onesto, A. T.; DeVita, V.

    1987-02-01

    This report contains the test results and assessments of seismic fragility tests performed on a 6-inch diameter piping system. The test was funded by the US Nuclear Regulatory Commission (NRC) and conducted by ETEC. The objective of the test was to investigate the ability of a representative nuclear piping system to withstand high level dynamic seismic and other loadings. Levels of loadings achieved during seismic testing were 20 to 30 times larger than normal elastic design evaluations to ASME Level D limits would permit. Based on failure data obtained during seismic and other dynamic testing, it was concluded that nuclear piping systems are inherently able to withstand much larger dynamic seismic loadings than permitted by current design practice criteria or predicted by the probabilistic risk assessment (PRA) methods and several proposed nonlinear methods of failure analysis.

  19. bessel functions for axisymmetric elasticity problems of the elastic ...

    African Journals Online (AJOL)

    HOD

    ELASTIC HALF SPACE SOIL: A POTENTIAL FUNCTION METHOD. C. C. Ike1 ... OF CIVIL ENGR., ENUGU STATE UNIVERSITY OF SCIENCE AND TECHNOLOGY, ENUGU, ENUGU STATE. ..... Elasticity, Third Edition,McGraw Hill, New York.

  20. Acquired disorders of elastic tissue: Part II. decreased elastic tissue.

    Science.gov (United States)

    Lewis, Kevan G; Bercovitch, Lionel; Dill, Sara W; Robinson-Bostom, Leslie

    2004-08-01

    Elastic fibers in the extracellular matrix are integral components of dermal connective tissue. The resilience and elasticity required for normal structure and function of the skin are attributable to the network of elastic tissue. Advances in our understanding of elastic tissue physiology provide a foundation for studying the pathogenesis of elastic tissue disorders. Many acquired disorders are nevertheless poorly understood owing to the paucity of reported cases. Several acquired disorders in which loss of dermal elastic tissue produces prominent clinical and histopathologic features have recently been described, including middermal elastolysis, papular elastorrhexis, and pseudoxanthoma-like papillary dermal elastolysis, which must be differentiated from more well-known disorders such as anetoderma, acquired cutis laxa, and acrokeratoelastoidosis. Learning objective At the conclusion of this learning activity, participants should have an understanding of the similarities and differences between acquired disorders of elastic tissue that are characterized by a loss of elastic tissue.

  1. Retinal vessel diameter changes induced by transient high perfusion pressure

    Institute of Scientific and Technical Information of China (English)

    Yin-Ying; Zhao; Ping-Jun; Chang; Fang; Yu; Yun-E; Zhao

    2014-01-01

    ·AIM: To investigate the effects of transient high perfusion pressure on the retinal vessel diameter and retinal ganglion cells.·METHODS: The animals were divided into four groups according to different infusion pressure and infusion time(60 mm Hg-3min, 60 mm Hg-5min, 100 mm Hg-3min, 100 mm Hg-5min). Each group consisted of six rabbits. The left eye was used as the experimental eye and the right as a control. Retinal vascular diameters were evaluated before, during infusion, immediately after infusion, 5min, 10 min and 30 min after infusion based on the fundus photographs. Blood pressure was monitored during infusion. The eyes were removed after 24 h.Damage to retinal ganglion cell(RGC) was analyzed by histology.·RESULTS: Retina became whiten and papilla optic was pale during perfusion. Measurements showed significant decrease in retinal artery and vein diameter during perfusion in all of the four groups at the proximal of the edge of the optic disc. The changes were significant in the 100 mm Hg-3min group and 100 mm Hg-5min group compared with 60 mm Hg-3min group(P 1=0.025, P 2=0.000).The diameters in all the groups recovered completely after 30 min of reperfusion. The number of RGC)showed no significant changes at the IOP in 100 mm Hg with5 min compared with contralateral untreated eye(P >0.05).·CONCLUSION: Transient fluctuations during infusion lead to temporal changes of retinal vessels, which could affect the retinal blood circulation. The RGCs were not affected by this transient fluctuation. Further studies are necessary to evaluate the effect of pressure during realtime phacoemusification on retinal blood circulation.

  2. Non-linear elastic deformations

    CERN Document Server

    Ogden, R W

    1997-01-01

    Classic in the field covers application of theory of finite elasticity to solution of boundary-value problems, analysis of mechanical properties of solid materials capable of large elastic deformations. Problems. References.

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

    Science.gov (United States)

    Sugimoto, Masataka; Hasegawa, Hideyuki; Kanai, Hiroshi

    2005-08-01

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

  4. 7 CFR 51.2850 - Diameter.

    Science.gov (United States)

    2010-01-01

    ... Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946... Diameter. Diameter means the greatest dimension measured at right angles to a straight line running from...

  5. 7 CFR 51.712 - Diameter.

    Science.gov (United States)

    2010-01-01

    ... Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946... § 51.712 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem...

  6. 7 CFR 51.651 - Diameter.

    Science.gov (United States)

    2010-01-01

    ... Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946...) Definitions § 51.651 Diameter. Diameter means the greatest dimension measured at right angles to a line from...

  7. Measuring angular diameters of extended sources

    NARCIS (Netherlands)

    van Hoof, PAM

    2000-01-01

    When measuring diameters of partially resolved sources like planetary nebulae, H II regions or galaxies, often a technique called Gaussian deconvolution is used. This technique yields a Gaussian diameter, which subsequently has to be multiplied by a conversion factor to obtain the true angular

  8. Predicting dynamics and rheology of blood flow: A comparative study of multiscale and low-dimensional models of red blood cells

    Science.gov (United States)

    Pan, Wenxiao; Fedosov, Dmitry A.; Caswell, Bruce; Karniadakis, George Em

    2011-01-01

    We compare the predictive capability of two mathematical models for red blood cells (RBCs) focusing on blood flow in capillaries and arterioles. Both RBC models as well as their corresponding blood flows are based on the dissipative particle dynamics (DPD) method, a coarse-grained molecular dynamics approach. The first model employs a multiscale description of the RBC (MS-RBC), with its membrane represented by hundreds or even thousands of DPD-particles connected by springs into a triangular network in combination with out-of-plane elastic bending resistance. Extra dissipation within the network accounts for membrane viscosity, while the characteristic biconcave RBC shape is achieved by imposition of constraints for constant membrane area and constant cell volume. The second model is based on a low-dimensional description (LD-RBC) constructed as a closed torus-like ring of only 10 large DPD colloidal particles. They are connected into a ring by worm-like chain (WLC) springs combined with bending resistance. The LD-RBC model can be fitted to represent the entire range of nonlinear elastic deformations as measured by optical-tweezers for healthy and for infected RBCs in malaria. MS-RBCs suspensions model the dynamics and rheology of blood flow accurately for any vessel size but this approach is computationally expensive for vessel diameters above 100 microns. Surprisingly, the much more economical suspensions of LD-RBCs also capture the blood flow dynamics and rheology accurately except for small-size vessels comparable to RBC diameter. In particular, the LD-RBC suspensions are shown to properly capture the experimental data for the apparent viscosity of blood and its cell-free layer (CFL) in tube flow. Taken together, these findings suggest a hierarchical approach in modeling blood flow in the arterial tree, whereby the MS-RBC model should be employed for capillaries and arterioles below 100 microns, the LD-RBC model for arterioles, and the continuum description for

  9. Mathematical methods in elasticity imaging

    CERN Document Server

    Ammari, Habib; Garnier, Josselin; Wahab, Abdul

    2015-01-01

    This book is the first to comprehensively explore elasticity imaging and examines recent, important developments in asymptotic imaging, modeling, and analysis of deterministic and stochastic elastic wave propagation phenomena. It derives the best possible functional images for small inclusions and cracks within the context of stability and resolution, and introduces a topological derivative-based imaging framework for detecting elastic inclusions in the time-harmonic regime. For imaging extended elastic inclusions, accurate optimal control methodologies are designed and the effects of uncertai

  10. Approximation by planar elastic curves

    DEFF Research Database (Denmark)

    Brander, David; Gravesen, Jens; Nørbjerg, Toke Bjerge

    2016-01-01

    We give an algorithm for approximating a given plane curve segment by a planar elastic curve. The method depends on an analytic representation of the space of elastic curve segments, together with a geometric method for obtaining a good initial guess for the approximating curve. A gradient......-driven optimization is then used to find the approximating elastic curve....

  11. Measurement of Elastic Modulus of Collagen Type I Single Fiber.

    Directory of Open Access Journals (Sweden)

    Pavel Dutov

    Full Text Available Collagen fibers are the main components of the extra cellular matrix and the primary contributors to the mechanical properties of tissues. Here we report a novel approach to measure the longitudinal component of the elastic moduli of biological fibers under conditions close to those found in vivo and apply it to type I collagen from rat tail tendon. This approach combines optical tweezers, atomic force microscopy, and exploits Euler-Bernoulli elasticity theory for data analysis. This approach also avoids drying for measurements or visualization, since samples are freshly extracted. Importantly, strains are kept below 0.5%, which appear consistent with the linear elastic regime. We find, surprisingly, that the longitudinal elastic modulus of type I collagen cannot be represented by a single quantity but rather is a distribution that is broader than the uncertainty of our experimental technique. The longitudinal component of the single-fiber elastic modulus is between 100 MPa and 360 MPa for samples extracted from different rats and/or different parts of a single tail. Variations are also observed in the fibril-bundle/fibril diameter with an average of 325±40 nm. Since bending forces depend on the diameter to the fourth power, this variation in diameter is important for estimating the range of elastic moduli. The remaining variations in the modulus may be due to differences in composition of the fibril-bundles, or the extent of the proteoglycans constituting fibril-bundles, or that some single fibrils may be of fibril-bundle size.

  12. Elastic platonic shells.

    Science.gov (United States)

    Yong, Ee Hou; Nelson, David R; Mahadevan, L

    2013-10-25

    On microscopic scales, the crystallinity of flexible tethered or cross-linked membranes determines their mechanical response. We show that by controlling the type, number, and distribution of defects on a spherical elastic shell, it is possible to direct the morphology of these structures. Our numerical simulations show that by deflating a crystalline shell with defects, we can create elastic shell analogs of the classical platonic solids. These morphologies arise via a sharp buckling transition from the sphere which is strongly hysteretic in loading or unloading. We construct a minimal Landau theory for the transition using quadratic and cubic invariants of the spherical harmonic modes. Our approach suggests methods to engineer shape into soft spherical shells using a frozen defect topology.

  13. Series elastic actuators

    Science.gov (United States)

    Williamson, Matthew M.

    1995-01-01

    This thesis presents the design, construction, control and evaluation of a novel for controlled actuator. Traditional force controlled actuators are designed from the premise that 'Stiffer is better'. This approach gives a high bandwidth system, prone to problems of contact instability, noise, and low power density. The actuator presented in this thesis is designed from the premise that 'Stiffness isn't everything'. The actuator, which incorporates a series elastic element, trades off achievable bandwidth for gains in stable, low noise force control, and protection against shock loads. This thesis reviews related work in robot force control, presents theoretical descriptions of the control and expected performance from a series elastic actuator, and describes the design of a test actuator constructed to gather performance data. Finally the performance of the system is evaluated by comparing the performance data to theoretical predictions.

  14. Introduction to linear elasticity

    CERN Document Server

    Gould, Phillip L

    2013-01-01

    Introduction to Linear Elasticity, 3rd Edition, provides an applications-oriented grounding in the tensor-based theory of elasticity for students in mechanical, civil, aeronautical, and biomedical engineering, as well as materials and earth science. The book is distinct from the traditional text aimed at graduate students in solid mechanics by introducing the subject at a level appropriate for advanced undergraduate and beginning graduate students. The author's presentation allows students to apply the basic notions of stress analysis and move on to advanced work in continuum mechanics, plasticity, plate and shell theory, composite materials, viscoelasticity and finite method analysis. This book also:  Emphasizes tensor-based approach while still distilling down to explicit notation Provides introduction to theory of plates, theory of shells, wave propagation, viscoelasticity and plasticity accessible to advanced undergraduate students Appropriate for courses following emerging trend of teaching solid mechan...

  15. Elastic plate spallation

    Science.gov (United States)

    Oline, L.; Medaglia, J.

    1972-01-01

    The dynamic finite element method was used to investigate elastic stress waves in a plate. Strain displacement and stress strain relations are discussed along with the stiffness and mass matrix. The results of studying point load, and distributed load over small, intermediate, and large radii are reported. The derivation of finite element matrices, and the derivation of lumped and consistent matrices for one dimensional problems with Laplace transfer solutions are included. The computer program JMMSPALL is also included.

  16. Visual function and retinal vessel diameters during hyperthermia in man

    DEFF Research Database (Denmark)

    Jensen, Bettina Hagström; Bram, Thue; Kappelgaard, Per

    2017-01-01

    laser ophthalmoscopy was used to measure retinal trunk vessel diameters. Assessment was made at baseline, during hyperthermia and after cooling. RESULTS: The induction of a mean increase in core body temperature of 1.02°C was associated with a 7.15-mmHg mean reduction in systolic blood pressure (p ... in cling film, tinfoil and warming blankets. Subsequent cooling was achieved by undressing. Flicker sensitivity (critical flicker fusion frequency) was chosen to assess temporal resolution, while the Freiburg Vision Test was used to determine spatial contrast sensitivity at 1.5 cycles per degree. Scanning...... diameters (CI95 0.96-4.94, p cooling. CONCLUSION: Increased core body temperature was accompanied by improved temporal visual resolution and retinal trunk...

  17. Elastic scattering of hadrons

    Science.gov (United States)

    Dremin, I. M.

    2013-01-01

    Colliding high-energy hadrons either produce new particles or scatter elastically with their quantum numbers conserved and no other particles produced. We consider the latter case here. Although inelastic processes dominate at high energies, elastic scattering contributes considerably (18-25%) to the total cross section. Its share first decreases and then increases at higher energies. Small-angle scattering prevails at all energies. Some characteristic features can be seen that provide information on the geometrical structure of the colliding particles and the relevant dynamical mechanisms. The steep Gaussian peak at small angles is followed by the exponential (Orear) regime with some shoulders and dips, and then by a power-law decrease. Results from various theoretical approaches are compared with experimental data. Phenomenological models claiming to describe this process are reviewed. The unitarity condition predicts an exponential fall for the differential cross section with an additional substructure to occur exactly between the low momentum transfer diffraction cone and a power-law, hard parton scattering regime under high momentum transfer. Data on the interference of the Coulomb and nuclear parts of amplitudes at extremely small angles provide the value of the real part of the forward scattering amplitude. The real part of the elastic scattering amplitude and the contribution of inelastic processes to the imaginary part of this amplitude (the so-called overlap function) are also discussed. Problems related to the scaling behavior of the differential cross section are considered. The power-law regime at highest momentum transfer is briefly described.

  18. Spontaneous high frequency diameter oscillations of larger retinal arterioles are reduced in type 2 diabetes mellitus

    DEFF Research Database (Denmark)

    Bek, Toke; Jeppesen, Peter; Kanters, Jørgen K.

    2013-01-01

    Diabetic retinopathy is characterized by morphological changes in the retina secondary to disturbances in retinal blood flow. Vasomotion is a mechanism for regulating blood flow by spontaneous oscillations in the diameter of retinal resistance arterioles, and has been shown to be disturbed outsid...

  19. Visual function and retinal vessel diameters during hyperthermia in man.

    Science.gov (United States)

    Jensen, Bettina Hagström; Bram, Thue; Kappelgaard, Per; Arvidsson, Henrik; Loskutova, Ekaterina; Munch, Inger Christine; Larsen, Michael

    2016-12-21

    To assess the effect of elevated core body temperature on temporal and spatial contrast sensitivity and retinal vessel diameters. The study included 13 healthy volunteers aged 20-37 years. Core body temperature elevation (target +1.1°C) was induced by wrapping the participants in cling film, tinfoil and warming blankets. Subsequent cooling was achieved by undressing. Flicker sensitivity (critical flicker fusion frequency) was chosen to assess temporal resolution, while the Freiburg Vision Test was used to determine spatial contrast sensitivity at 1.5 cycles per degree. Scanning laser ophthalmoscopy was used to measure retinal trunk vessel diameters. Assessment was made at baseline, during hyperthermia and after cooling. The induction of a mean increase in core body temperature of 1.02°C was associated with a 7.15-mmHg mean reduction in systolic blood pressure (p < 0.01), a 10.6-mmHg mean reduction in diastolic blood pressure (p < 0.01), a mean increase in pulse rate of 36.3 bpm (p < 0.0001), a 2.66% improvement in flicker sensitivity (CI95 1.37-3.94, p < 0.001), a 2.80% increase in retinal artery diameters (CI95 1.09-4.51, p < 0.01) and a 2.95% increase in retinal vein diameters (CI95 0.96-4.94, p < 0.01). There was no detectable effect of temperature on spatial contrast sensitivity. All ocular test parameters returned to baseline levels after cooling. Increased core body temperature was accompanied by improved temporal visual resolution and retinal trunk vessel dilation. The results suggest that hyperthermia is associated with enhanced retinal function and increased retinal metabolism. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  20. Elastic response and wrinkling onset of curved elastic membranes subjected to indentation test.

    Science.gov (United States)

    Bernal, R; Tassius, Ch; Melo, F; Géminard, J-Ch

    2011-02-01

    Starting from a polymeric-fluid droplet, by vulcanization of the fluid free surface, curved elastic membranes, several nanometers thick and a few millimeters in diameter, which enclose a constant fluid volume, are produced. In an indentation-type test, carried out by pushing the membrane along its normal by means of a micro-needle, under some conditions, wrinkles are likely to appear around the contact region. Interestingly, we observe that the instability does not significantly alter the force-displacement relation: the relation between the force and the displacement remains linear and the associated stiffness is simply proportional to the tension of the membrane. In addition, we determine that the wrinkles develop when the stretching modulus of the membrane compares with its tension, which provides a useful method to estimate the elastic constant.

  1. Impact Structures: What Does Crater Diameter Mean?

    Science.gov (United States)

    Turtle, E. P.; Pierazzo, E.; Collins, G. S.; Osinski, G. R.; Melosh, H. J.; Morgan, J. V.; Reimold, W. U.; Spray, J. G.

    2004-03-01

    Crater diameter is an important parameter in energy scaling and impact simulations. However, disparate types of data make the use of consistent metrics difficult. We suggest a consistent terminology and discuss it in the context of several examples.

  2. 二甲双胍对2型糖尿病患者血液流变学及血管弹性的影响%Effects of Metformin on Hemorheology and Blood Vessel Elasticity in Patients With Type 2 Diabetes Mellitus

    Institute of Scientific and Technical Information of China (English)

    何咏梅; 杨中顺; 黄隐

    2016-01-01

    目的 探讨二甲双胍对2型糖尿病患者血液流变学及血管弹性的影响.方法 90例2型糖尿病患者,随机分为观察组和对照组,每组各45例.对照组患者给予控制饮食、运动锻炼及降糖等2型糖尿病一般治疗,观察组患者在一般治疗基础上给予二甲双胍治疗.结果 观察组2型糖尿病患者临床治疗总有效率为93.33%,高于对照组2型糖尿病患者,临床治疗总有效率71.11%,差异有统计学意义(=7.601,P<0.01).治疗后,观察组患者血浆比黏度、全血比黏度、纤维蛋白原、红细胞聚集及血细胞容积指数水平均低于对照组患者血浆比黏度、全血比黏度、纤维蛋白原、红细胞聚集及血细胞容积指数水平,差异有统计学意义(P<0.01).治疗后,观察组患者血管弹性指标PEVβ、β、AI及Ep水平变化低于对照组患者血管弹性指标PEVβ、β、AI及Ep水平,且观察组患者AC水平高于对照组患者AC水平,差异有统计学意义(P<0.01).治疗后,观察组患者FPG、2hPG及HbA1c水平低于对照组患者FPG、2hPG及HbA1c水平,差异有统计学意义(P<0.01).结论 二甲双胍应用于2型糖尿病患者,不仅能够发挥良好的降糖作用,还可有效改善长期高血糖引起的血液流变学及血管弹性参数异常升高现象,促进血液循环及血管弹性逐渐恢复.%Objective To investigate the effects of metformin on blood rheology and vascular elasticity in patients with type 2 diabetes mellitus. Methods 2 cases of Type 90 diabetes patients were randomly divided into observation group and control group, each group of 45 cases. Patients in control group were given controlling diet, exercise,blood sugar and other type 2 diabetes general treatment, the observation group were treated with metformin on the basis of general treatment. Results The total effective rate of clinical treatment in the observation group patients with type 2 diabetes was 93. 33%, higher than that of the control group

  3. Defining a Minimum End Mill Diameter

    Directory of Open Access Journals (Sweden)

    A. E. Dreval'

    2015-01-01

    Full Text Available Industrial observations show that the standard mill designs in many cases do not provide a complete diversity of manufacturing operations, and a lot of enterprises are forced to design and manufacture special (original designs of tools. The information search has revealed a lack of end mill diameter calculations in publications. There is a proposal to calculate the end mill diameter either by empirical formulas [2, 3], or by selection from the tables [4].To estimate a minimum diameter of the end mill to perform the specified manufacturing operations based on the mill body strength the formulas are obtained. The initial data for calculation are the flow sheet of milling operation and properties of processed and tool materials. The end mill is regarded, as a cantilevered beam of the circular cross section having Dс diameter (mill core diameter with overhang Lв from rigid fixing and loaded by the maximum bending force and torque.In deriving the formulas were used the following well-reasoned assumptions based on the analysed sizes of the structural elements of the standard mills: a diameter of mill core is linearly dependent on the mill diameter and the overhang; the 4τ 2 to σ 2 4τ2 ratio is constant and equal to 0.065 for contour milling and 0.17 for slot milling.The formulas for calculating the minimum diameter are as follows:  3 обр в 1 121 1.1  K S L L D m C z    for contour milling;  3 обр в 1 207 1.1  K S L L D m C z    for slot milling.Obtained dependences that allow defining a minimum diameter of the end mill in terms of ensuring its strength can be used to design mills for contour milling with radius transition sections, holes of different diameters in the body parts and other cases when for processing a singlemill is preferable.Using the proposed dependencies for calculating a feed of the maximum tolerable strength is reasonable in designing the mills for slots.Assumptions used in deriving

  4. Unit distances and diameters in Euclidean spaces

    CERN Document Server

    Swanepoel, Konrad J

    2007-01-01

    We show that the maximum number of unit distances or of diameters in a set of n points in d-dimensional Euclidean space is attained only by specific types of Lenz constructions, for all d >= 4 and n sufficiently large, depending on d. As a corollary we determine the exact maximum number of unit distances for all even d >= 6, and the exact maximum number of diameters for all d >= 4, for all $n$ sufficiently large, depending on d.

  5. Shaft Diameter Measurement Using Structured Light Vision

    OpenAIRE

    2015-01-01

    A method for measuring shaft diameters is presented using structured light vision measurement. After calibrating a model of the structured light measurement, a virtual plane is established perpendicular to the measured shaft axis and the image of the light stripe on the shaft is projected to the virtual plane. On the virtual plane, the center of the measured shaft is determined by fitting the projected image under the geometrical constraints of the light stripe, and the shaft diameter is meas...

  6. Appendiceal diameter: CT versus sonographic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Orscheln, Emily S. [University of Cincinnati Medical Center, Department of Radiology, Cincinnati, OH (United States); Trout, Andrew T. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States)

    2016-03-15

    Ultrasound and CT are the dominant imaging modalities for assessment of suspected pediatric appendicitis, and the most commonly applied diagnostic criterion for both modalities is appendiceal diameter. The classically described cut-off diameter for the diagnosis of appendicitis is 6 mm when using either imaging modality. To demonstrate the fallacy of using the same cut-off diameter for both CT and US in the diagnosis of appendicitis. We conducted a retrospective review of patients younger than 18 years who underwent both US and CT of the appendix within 24 h. The shortest transverse dimension of the appendix was measured at the level of the proximal, mid and distal appendix on US and CT images. We compared mean absolute difference in appendiceal diameter between US and CT, using the paired t-test. We reviewed exams of 155 children (58.7% female) with a mean age of 11.3 ± 4.2 years; 38 of the children (24.5%) were diagnosed with appendicitis. The average time interval between US and CT was 7.0 ± 5.4 h. Mean appendiceal diameter measured by CT was significantly larger than that measured by US in cases without appendicitis (5.3 ± 1.0 mm vs. 4.7 ± 1.1 mm, P < 0.0001) and in cases with appendicitis (8.3 ± 2.2 mm vs. 7.0 ± 2.0 mm, P < 0.0001). Mean absolute diameter difference at any location along the appendix was 1.3-1.4 mm in normal appendices and 2 mm in cases of appendicitis. Measured appendiceal diameter differs between US and CT by 1-2 mm, calling into question use of the same diameter cut-off (6 mm) for both modalities for the diagnosis of appendicitis. (orig.)

  7. Arteriolar Diameters in Glaucomatous Eyes with Single-Hemifield Damage.

    Science.gov (United States)

    Russo, Andrea; Costagliola, Ciro; Rizzoni, Damiano; Ghilardi, Nausica; Turano, Raffaele; Semeraro, Francesco

    2016-05-01

    To examine the association between retinal arteriolar caliber and lumen, retinal sensitivity (RS), and retinal nerve fiber layer (RNFL) thickness in glaucomatous eyes with single-hemifield loss. We conducted a prospective, nonrandomized, case-control study of 20 eyes of 20 patients with glaucoma with visual field damage confined to a single hemifield. The control group was composed of 20 eyes of 20 normal subjects. For all the eyes, we performed optical coherence tomography to assess the RNFL and standard automated perimetry to evaluate RS. External and internal arteriolar diameters were assessed in vivo using scanning laser Doppler flowmetry. The RNFL was significantly thinner in glaucomatous eyes than in normal eyes (p < 0.001). In glaucomatous eyes, a positive correlation between sectorial RNFL thickness and the corresponding external and internal arteriolar diameters was found (r = 0.43, p = 0.05; r = 0.63, p = 0.003, respectively). The internal arteriolar diameter significantly correlated with RS in the corresponding abnormal hemifield (r = 0.44, p = 0.04). Compared with the normal hemifield, the internal arteriolar diameter, RNFL thickness, and RS were significantly reduced, whereas the external arteriolar diameter was unchanged in the abnormal hemifield. In glaucomatous eyes with single-hemifield damage, attenuation of retinal vessels was associated with a thinner RNFL and reduced RS. Moreover, a narrower lumen with increased wall-to-lumen ratio was found in the abnormal hemifield, supporting the hypothesis that vessel narrowing is likely secondary to a lower demand for blood flow in the glaucomatous areas of the retina.

  8. Study of elastic system fibers in human gingiva

    Directory of Open Access Journals (Sweden)

    Walter Augusto Soares Machado

    Full Text Available Objective: To map the participation of the elastic system fibers of human gingiva. Methods: To conduct this study, fragments of human gingiva from ten individuals aged between 18 and 60 years, removed after periodontal surgery for prosthetic purposes, were analyzed by the histochemical and immuno-histochemical methods, to evaluate the participation of the elastic system fibers in this tissue. Results: The results demonstrated the presence of three type of elastic system fibers, that is to say, oxitalan, elaunin and elastic fibers,distributed as follows: 1 the oxitalan fibers form a network of thin fibers, located close to the basal membrane, at the level of the conjunctive tissue papillae; 2 elaunin fibers are found in close contact with the oxitalan fibers in the papillary and submaxillary regions, following the collagen fiber bundles; 3 a small quantity of elastic fibers were observed, dispersed throughout the deeper conjunctive tissue and around the blood vessels. Conclusion: The three types of elastic system fibers, that is, oxitalan, elaunin and elastic fibers are normal constituents of the extracellular matrixof human gingiva conjunctive tissue.

  9. Arterial Elasticity, Strength, Fatigue, and Endurance in Older Women

    Directory of Open Access Journals (Sweden)

    Gary R. Hunter

    2014-01-01

    Full Text Available Arterial health may influence muscle function in older adults. Study purpose was to determine whether arterial elasticity is related to strength, central and peripheral fatigue, fatigue at rest, and treadmill endurance. Subjects were 91 healthy women aged >60. Treadmill endurance and maximal oxygen uptake (VO2 max were measured. Peripheral and central fatigue for the knee extensors were evaluated using two isometric fatigue tests (one voluntary and one adding electrical stimulation. Arterial elasticity was determined using radial artery pulse wave analysis. Linear multiple regression was used in statistical analysis. Large artery elasticity was associated with central fatigue (P<0.01 and treadmill endurance (P<0.02 after adjusting for VO2 max and knee extension strength. Subjective fatigue at rest was related to large artery elasticity after adjusting for ethnic origin (<0.02. Strength was significantly related to small artery elasticity after adjusting for ethnic origin, leg lean tissue, age, and blood pressure. Arterial elasticity is independently related to strength and fatigue in older women, especially in the central nervous system where arterial elasticity is independently related to perceptions of fatigue at rest and central fatigue. These results suggest that arterial health may be involved with the ability of the central nervous system to activate muscle in older women.

  10. Mathematical foundations of elasticity

    CERN Document Server

    Marsden, Jerrold E

    1994-01-01

    This advanced-level study approaches mathematical foundations of three-dimensional elasticity using modern differential geometry and functional analysis. It is directed to mathematicians, engineers and physicists who wish to see this classical subject in a modern setting with examples of newer mathematical contributions. Prerequisites include a solid background in advanced calculus and the basics of geometry and functional analysis.The first two chapters cover the background geometry ― developed as needed ― and use this discussion to obtain the basic results on kinematics and dynamics of con

  11. Collagen fibril diameter and leather strength.

    Science.gov (United States)

    Wells, Hannah C; Edmonds, Richard L; Kirby, Nigel; Hawley, Adrian; Mudie, Stephen T; Haverkamp, Richard G

    2013-11-27

    The main structural component of leather and skin is type I collagen in the form of strong fibrils. Strength is an important property of leather, and the way in which collagen contributes to the strength is not fully understood. Synchrotron-based small angle X-ray scattering (SAXS) is used to measure the collagen fibril diameter of leather from a range of animals, including sheep and cattle, that had a range of tear strengths. SAXS data were fit to a cylinder model. The collagen fibril diameter and tear strength were found to be correlated in bovine leather (r(2) = 0.59; P = 0.009), with stronger leather having thicker fibrils. There was no correlation between orientation index, i.e., fibril alignment, and fibril diameter for this data set. Ovine leather showed no correlation between tear strength and fibril diameter, nor was there a correlation across a selection of other animal leathers. The findings presented here suggest that there may be a different structural motif in skin compared with tendon, particularly ovine skin or leather, in which the diameter of the individual fibrils contributes less to strength than fibril alignment does.

  12. Confocal microscopy for automatic texture analysis of elastic fibers in histologic preparations

    Science.gov (United States)

    Adam, R. L.; Vieira, G.; Ferro, D. P.; de Thomaz, A. A.; Cesar, C., L.; Metze, K.

    2009-07-01

    Elastic fibers are an important component of many organs and tissues, such as skin, lungs, arteries, ligaments, intervertebral discs and cartilage Their function is to endow tissues with elastic recoil and resilience, to act as an important adhesion template for cells, and to regulate growth factor availability (1,2). Loss or remodeling of the elastic fiber texture occurs in many diseases. Degeneration and fragmentation of elastic fibers and aging are intimately related (3). Recently, the importance of elastin for the study of malignant tumor progression has been emphasized (4,5). Elastic tissue may be a significant reservoir of angiostatic molecules and soluble elastin as well as elastin peptides, that are inhibitors of the metastatic process in experimental tumor models (4). Elastic fibers are involved in the anatomic remodeling of chronic pulmonary diseases (6) and, especially, of diseases of the arterial wall (7, 8). The study of these phenomena is important for the understanding of the pathophysiologic basis of the diseases. Recently the role of elastic fibers in small diameter vascular graft design has been emphasized (2). The possibility to regenerate or engineer elastic fibres and tissues creates an important challenge, not only to understand the molecular basis of elastic-fibre biology (1,2), but also of its spatial arrangement and remodeling in the diseased tissues. Subtle changes of the complex elastic fiber network may be involved in the pathogenesis of diseases. Therefore a precise and objective histopathologic description is necessary.

  13. Polysoaps: Configurations and Elasticity

    Science.gov (United States)

    Halperin, A.

    1997-03-01

    Simple polymers are very long, flexible, linear molecules. Amphiphiles, soaps, are small molecules comprising of a part that prefers water over oil and a part that prefers oil over water. By combining the two we arrive at an interesting, little explored, class of materials: Polysoaps. These comprise of a water soluble backbone incorporating, at intervals, covalently bound amphiphilic monomers. In water, the polymerised amphiphiles aggregate into self assembled units known as micelles. This induces a dramatic modification of the spatial configurations of the polymers. What were featureless random coils now exhibit intramolecular, hierachial self organisation. Due to this self organisation it is necessary to modify the paradigms describing the large scale behaviour of these polymers: Their configurations, dimensions and elasticity. Understanding the behaviour of these polymers is of practical interest because of their wide range of industrial applications, ranging from cosmetics to paper coating. It is of fundamental interest because polysoaps are characterised by a rugged free energy landscape that is reminiscent of complex systems such as proteins and glasses. The talk concerns theoretical arguments regarding the following issues: (i) The design parameters that govern the spatial configurations of the polysoaps, (ii) The interaction between polysoaps and free amphiphiles, (iii) The effect of the intramolecular self organisation on the elasticity of the chains.

  14. Elastic emission polishing

    Energy Technology Data Exchange (ETDEWEB)

    Loewenthal, M.; Loseke, K.; Dow, T.A.; Scattergood, R.O.

    1988-12-01

    Elastic emission polishing, also called elastic emission machining (EEM), is a process where a stream of abrasive slurry is used to remove material from a substrate and produce damage free surfaces with controlled surface form. It is a noncontacting method utilizing a thick elasto-hydrodynamic film formed between a soft rotating ball and the workpiece to control the flow of the abrasive. An apparatus was built in the Center, which consists of a stationary spindle, a two-axis table for the workpiece, and a pump to circulate the working fluid. The process is controlled by a programmable computer numerical controller (CNC), which presently can operate the spindle speed and movement of the workpiece in one axis only. This apparatus has been used to determine material removal rates on different material samples as a function of time, utilizing zirconium oxide (ZrO{sub 2}) particles suspended in distilled water as the working fluid. By continuing a study of removal rates the process should become predictable, and thus create a new, effective, yet simple tool for ultra-precision mechanical machining of surfaces.

  15. Diameter Preserving Surjection on Alternate Matrices

    Institute of Scientific and Technical Information of China (English)

    Li Ping HUANG

    2009-01-01

    Let F be a field with |F| ≥ 3, Km be the set of all m × m (m ≥ 4) alternate matrices over F. The arithmetic distance of A, B ∈ Km is d(A, B) := rank(A- B). If d(A, B) = 2, then A and B are said to be adjacent. The diameter of Km is max{d(A, B) : A, B ∈ Km}. Assume that ψ : Km→ Km is a map. We prove the following are equivalent: (a) ψ is a diameter preserving surjection in both directions, (b) ψ is both an adjacency preserving surjection and a diameter preserving map, (c) ψ is a bijective map which preserves the arithmetic distance.

  16. A Home Experiment in Elasticity

    CERN Document Server

    Aguirregabiria, J M; Rivas, M

    2006-01-01

    We analyze a simple problem in elasticity: the \\emph{initial} motion of an elastic bar that after being hanged from an end is suddenly released. In a second problem a point mass is attached on the top of the bar. The analytical solutions uncover some unexpected properties, which can be checked, with a digital camera or camcorder, in an alternative setup in which a spring is substituted for the bar. The theoretical model and the experiments are useful to understand the similarities and differences between the elastic properties of bar and spring. Students can take advantage of the home experiments to improve their understanding of elastic waves.

  17. The truth about small-diameter implants.

    Science.gov (United States)

    Christensen, Gordon J; Child, Paul L

    2010-05-01

    SDIs that are treatment planned correctly, placed and loaded properly, and are within a well-adjusted occlusion, are working in an excellent manner for the patients described in this article. It is time for those practitioners unfamiliar with SDIs and their uses to discontinue their discouragement of this technique. SDIs are easily placed, minimally invasive, and a true service to those patients described. They do not replace conventional diameter implants; however, they are a significant and important augmentation to the original root-form implant concept. There is obvious evidence of the growing acceptance of small-diameter implants by both general practitioners and specialists.

  18. THERMAL EVALUATION OF DIFFERENT DRIFT DIAMETER SIZES

    Energy Technology Data Exchange (ETDEWEB)

    H.M. Wade

    1999-01-04

    The purpose of this calculation is to estimate the thermal response of a repository-emplaced waste package and its corresponding drift wall surface temperature with different drift diameters. The case examined is that of a 21 pressurized water reactor (PWR) uncanistered fuel (UCF) waste package loaded with design basis spent nuclear fuel assemblies. This calculation evaluates a 3.5 meter to 6.5 meter drift diameter range in increments of 1.0 meters. The time-dependent temperatures of interest, as determined by this calculation, are the spent nuclear fuel cladding temperature, the waste package surface temperature, and the drift wall surface temperature.

  19. Shaft Diameter Measurement Using Structured Light Vision.

    Science.gov (United States)

    Liu, Siyuan; Tan, Qingchang; Zhang, Yachao

    2015-08-12

    A method for measuring shaft diameters is presented using structured light vision measurement. After calibrating a model of the structured light measurement, a virtual plane is established perpendicular to the measured shaft axis and the image of the light stripe on the shaft is projected to the virtual plane. On the virtual plane, the center of the measured shaft is determined by fitting the projected image under the geometrical constraints of the light stripe, and the shaft diameter is measured by the determined center and the projected image. Experiments evaluated the measuring accuracy of the method and the effects of some factors on the measurement are analyzed.

  20. Shaft Diameter Measurement Using Structured Light Vision

    Directory of Open Access Journals (Sweden)

    Siyuan Liu

    2015-08-01

    Full Text Available A method for measuring shaft diameters is presented using structured light vision measurement. After calibrating a model of the structured light measurement, a virtual plane is established perpendicular to the measured shaft axis and the image of the light stripe on the shaft is projected to the virtual plane. On the virtual plane, the center of the measured shaft is determined by fitting the projected image under the geometrical constraints of the light stripe, and the shaft diameter is measured by the determined center and the projected image. Experiments evaluated the measuring accuracy of the method and the effects of some factors on the measurement are analyzed.

  1. Elastic Properties of the Single-Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    O.B. Protsenko

    2012-03-01

    Full Text Available In this paper the elastic properties of two main types of single-walled carbon nanotubes (armchair and zigzag were simulated by analytical molecular mechanics models. The aim of this work is investigation and comparison of Young’s modulus, shear modulus and Poisson’s ratio variations of different types of tubes as functions of diameter. We obtained a set of closed-form expressions for the size-dependent elastic properties of armchair (n, n and zigzag (n, 0 tubes, which are basic for constructing mathematical models. Using those models elastic properties of single-walled nanotubes were evaluated. It was predicted that zigzag tube is more sensitive to chirality then armchair. Young’s and shear modules of both tubes were decreasing with diameter increasing. Poisson’s ratio was ranging from 0.16 to 0.29 and from 0.32 to 0.42 for an armchair and zigzag tubes respectively, but it was independent on chirality. It can be seen that predicted values of elastic characteristics for zigzag tube are larger then that for armchair tube, especially for smaller tubes. Results of this research can be used for design, analysis and evaluating of functioning and creating new materials based on carbon nanotubes.

  2. Influence of tube's diameter on boiling heat transfer performance in small diameter tubes

    Science.gov (United States)

    Gan, Chengjun; Wang, Weicheng; Zhang, Lining

    1998-03-01

    This paper reports the experiments of evaporation study in 6 mm inner copper diameter tubes using HFC-134a, HCFC-22 and CFC-12 as working fluid. The results show that the evaporation heat transfer coefficient increases with the decreasing of inner diameter of tubes. A new concept of non-dimensional tube diameter U is proposed in this paper for correction of the influence of the tube diameter on the evaporation heat transfer coefficient. And further, a convenient empirical correction method is presented.

  3. Influence of Tube‘s Diameter on Boling Heat Transfer Performance in Small Diameter Tubes

    Institute of Scientific and Technical Information of China (English)

    GanChengjun; WangWeicheng; 等

    1998-01-01

    This paper reports the experiments of evaporation study in 6 mm inner copper diameter tubes using HFC-134a,HCFC-22 and CFC-12 as working fluid.The results show that the evaporation heat transfer cofeeicient increasese with the decreasing of inner diameter of tubes,A new concept of nondimensional tube diameter U is proposed in this paper for correction of the influence of the tube diameter on the evaporation heat transfer coefficient.And further,a conveinent empirical correction method is preseted.

  4. Numerical Analysis of Large Diameter Butterfly Valve

    Science.gov (United States)

    Youngchul, Park; Xueguan, Song

    In this paper, a butterfly valve with the diameter of 1,800 mm was studied. Three-dimensional numerical technique by using commercial code CFX were conducted to observe the flow patterns and to measure flow coefficient, hydrodynamic torque coefficient and so on, when the large butterfly valve operated with various angles and uniform incoming velocity.

  5. Reduced artery diameters in Klinefelter syndrome.

    Science.gov (United States)

    Foresta, C; Caretta, N; Palego, P; Ferlin, A; Zuccarello, D; Lenzi, A; Selice, R

    2012-10-01

    Various epidemiological studies in relatively large cohorts of patients with Klinefelter syndrome (KS) described the increased morbidity and mortality in these subjects. Our aim was to study the structure and function of arteries in different districts to investigate in these subjects possible alterations. A total of 92 patients having non-mosaic KS, diagnosed in Centre for Human Reproduction Pathology at the University of Padova, and 50 age-matched healthy male controls were studied. Klinefelter syndrome subjects and controls evaluation included complete medical history, physical examination, measurement of concentrations of the reproductive hormones, lipidic and glycidic metabolism, AR function and sensitivity, ultrasound examinations (diameters, carotid intima-media thickness and brachial flow-mediated dilation) of brachial, common carotid and common femoral artery and abdominal aorta. Klinefelter syndrome patients showed significantly reduced artery diameters in all districts evaluated. On the contrary no statistically significant difference was found in cIMT and brachial FMD values between KS patients and controls. Furthermore, we found no statistically significant correlation of artery diameters with reproductive hormones, metabolic parameters, anthropometric measures and weighted CAG repeats. To our knowledge, this is the first study finding a reduced artery diameter in several districts in KS patients compared with that of normal male subjects and overlapping to that of female subjects. We have not an explanation for this phenomenon, even if a possible involvement of genes controlling the development of vascular system might be hypothesized, and further research is required to verify this hypothesis.

  6. Physics of cell elasticity, shape and adhesion

    Science.gov (United States)

    Safran, S. A.; Gov, N.; Nicolas, A.; Schwarz, U. S.; Tlusty, T.

    2005-07-01

    We review recent theoretical work that analyzes experimental measurements of the shape, fluctuations and adhesion properties of biological cells. Particular emphasis is placed on the role of the cytoskeleton and cell elasticity and we contrast the shape and adhesion of elastic cells with fluid-filled vesicles. In red blood cells (RBC), the cytoskeleton consists of a two-dimensional network of spectrin proteins. Our analysis of the wavevector and frequency dependence of the fluctuation spectrum of RBC indicates that the spectrin network acts as a confining potential that reduces the fluctuations of the lipid bilayer membrane. However, since the cytoskeleton is only sparsely connected to the bilayer, one cannot regard the composite cytoskeleton-membrane as a polymerized object with a shear modulus. The sensitivity of RBC fluctuations and shapes to ATP concentration may reflect topological defects induced in the cytoskeleton network by ATP. The shapes of cells that adhere to a substrate are strongly determined by the cytoskeletal elasticity that can be varied experimentally by drugs that depolymerize the cytoskeleton. This leads to a tension-driven retraction of the cell body and a pearling instability of the resulting ray-like protrusions. Recent experiments have shown that adhering cells exert polarized forces on substrates. The interactions of such “force dipoles” in either bulk gels or on surfaces can be used to predict the nature of self-assembly of cell aggregates and may be important in the formation of artificial tissues. Finally, we note that cell adhesion strongly depends on the forces exerted on the adhesion sites by the tension of the cytoskeleton. The size and shape of the adhesion regions are strongly modified as the tension is varied and we present an elastic model that relates this tension to deformations that induce the recruitment of new molecules to the adhesion region. In all these examples, cell shape and adhesion differ from vesicle shape and

  7. Questions about elastic waves

    CERN Document Server

    Engelbrecht, Jüri

    2015-01-01

    This book addresses the modelling of mechanical waves by asking the right questions about them and trying to find suitable answers. The questions follow the analytical sequence from elementary understandings to complicated cases, following a step-by-step path towards increased knowledge. The focus is on waves in elastic solids, although some examples also concern non-conservative cases for the sake of completeness. Special attention is paid to the understanding of the influence of microstructure, nonlinearity and internal variables in continua. With the help of many mathematical models for describing waves, physical phenomena concerning wave dispersion, nonlinear effects, emergence of solitary waves, scales and hierarchies of waves as well as the governing physical parameters are analysed. Also, the energy balance in waves and non-conservative models with energy influx are discussed. Finally, all answers are interwoven into the canvas of complexity.

  8. Elastic fibres and vascular structure in hypertension.

    Science.gov (United States)

    Arribas, Silvia M; Hinek, Aleksander; González, M Carmen

    2006-09-01

    Blood vessels are dynamic structures composed of cells and extracellular matrix (ECM), which are in continuous cross-talk with each other. Thus, cellular changes in phenotype or in proliferation/death rate affect ECM synthesis. In turn, ECM elements not only provide the structural framework for vascular cells, but they also modulate cellular function through specific receptors. These ECM-cell interactions, together with neurotransmitters, hormones and the mechanical forces imposed by the heart, modulate the structural organization of the vascular wall. It is not surprising that pathological states related to alterations in the nervous, humoral or haemodynamic environment-such as hypertension-are associated with vascular wall remodeling, which, in the end, is deleterious for cardiovascular function. However, the question remains whether these structural alterations are simply a consequence of the disease or if there are early cellular or ECM alterations-determined either genetically or by environmental factors-that can predispose to vascular remodeling independent of hypertension. Elastic fibres might be key elements in the pathophysiology of hypertensive vascular remodeling. In addition to the well known effects of hypertension on elastic fibre fatigue and accelerated degradation, leading to loss of arterial wall resilience, recent investigations have highlighted new roles for individual components of elastic fibres and their degradation products. These elements can act as signal transducers and regulate cellular proliferation, migration, phenotype, and ECM degradation. In this paper, we review current knowledge regarding components of elastic fibres and discuss their possible pathomechanistic associations with vascular structural abnormalities and with hypertension development or progression.

  9. The optimal elastic flagellum

    Science.gov (United States)

    Spagnolie, Saverio E.; Lauga, Eric

    2010-03-01

    Motile eukaryotic cells propel themselves in viscous fluids by passing waves of bending deformation down their flagella. An infinitely long flagellum achieves a hydrodynamically optimal low-Reynolds number locomotion when the angle between its local tangent and the swimming direction remains constant along its length. Optimal flagella therefore adopt the shape of a helix in three dimensions (smooth) and that of a sawtooth in two dimensions (nonsmooth). Physically, biological organisms (or engineered microswimmers) must expend internal energy in order to produce the waves of deformation responsible for the motion. Here we propose a physically motivated derivation of the optimal flagellum shape. We determine analytically and numerically the shape of the flagellar wave which leads to the fastest swimming for a given appropriately defined energetic expenditure. Our novel approach is to define an energy which includes not only the work against the surrounding fluid, but also (1) the energy stored elastically in the bending of the flagellum, (2) the energy stored elastically in the internal sliding of the polymeric filaments which are responsible for the generation of the bending waves (microtubules), and (3) the viscous dissipation due to the presence of an internal fluid. This approach regularizes the optimal sawtooth shape for two-dimensional deformation at the expense of a small loss in hydrodynamic efficiency. The optimal waveforms of finite-size flagella are shown to depend on a competition between rotational motions and bending costs, and we observe a surprising bias toward half-integer wave numbers. Their final hydrodynamic efficiencies are above 6%, significantly larger than those of swimming cells, therefore indicating available room for further biological tuning.

  10. The First Law of Elasticity

    Science.gov (United States)

    Girill, T. R.

    1972-01-01

    The Boyle-Mariotte gas law was formulated in terms of pneumatic springs," subsumed by Hooke under his own stress-strain relation, and generally regarded as a law of elasticity. The subsequent development of Boyle's principle and elasticity provide thought-provoking test cases for Kuhn's notations of paradigm and puzzle solving in physics.…

  11. PAGOSA Sample Problem. Elastic Precursor

    Energy Technology Data Exchange (ETDEWEB)

    Weseloh, Wayne N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Clancy, Sean Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-02-03

    A PAGOSA simulation of a flyer plate impact which produces an elastic precursor wave is examined. The simulation is compared to an analytic theory for the Mie-Grüneisen equation of state and an elastic-perfectly-plastic strength model.

  12. Elastic model of dry friction

    Energy Technology Data Exchange (ETDEWEB)

    Larkin, A. I.; Khmelnitskii, D. E., E-mail: dekl2@cam.ac.uk [Landau Institute for Theoretical Physics (Russian Federation)

    2013-09-15

    Friction of elastic bodies is connected with the passing through the metastable states that arise at the contact of surfaces rubbing against each other. Three models are considered that give rise to the metastable states. Friction forces and their dependence on the pressure are calculated. In Appendix A, the contact problem of elasticity theory is solved with adhesion taken into account.

  13. Blood sugar test - blood

    Science.gov (United States)

    ... blood glucose level ( hypoglycemia ) may be due to: Hypopituitarism (a pituitary gland disorder) Underactive thyroid gland or ... tonic-clonic seizure Glucagon blood test Glucagonoma Hyperthyroidism Hypopituitarism Hypothyroidism Insulinoma Low blood sugar Multiple endocrine neoplasia ( ...

  14. Approaching the ideal elastic strain limit in silicon nanowires.

    Science.gov (United States)

    Zhang, Hongti; Tersoff, Jerry; Xu, Shang; Chen, Huixin; Zhang, Qiaobao; Zhang, Kaili; Yang, Yong; Lee, Chun-Sing; Tu, King-Ning; Li, Ju; Lu, Yang

    2016-08-01

    Achieving high elasticity for silicon (Si) nanowires, one of the most important and versatile building blocks in nanoelectronics, would enable their application in flexible electronics and bio-nano interfaces. We show that vapor-liquid-solid-grown single-crystalline Si nanowires with diameters of ~100 nm can be repeatedly stretched above 10% elastic strain at room temperature, approaching the theoretical elastic limit of silicon (17 to 20%). A few samples even reached ~16% tensile strain, with estimated fracture stress up to ~20 GPa. The deformations were fully reversible and hysteresis-free under loading-unloading tests with varied strain rates, and the failures still occurred in brittle fracture, with no visible sign of plasticity. The ability to achieve this "deep ultra-strength" for Si nanowires can be attributed mainly to their pristine, defect-scarce, nanosized single-crystalline structure and atomically smooth surfaces. This result indicates that semiconductor nanowires could have ultra-large elasticity with tunable band structures for promising "elastic strain engineering" applications.

  15. Cell elasticity determines macrophage function.

    Directory of Open Access Journals (Sweden)

    Naimish R Patel

    Full Text Available Macrophages serve to maintain organ homeostasis in response to challenges from injury, inflammation, malignancy, particulate exposure, or infection. Until now, receptor ligation has been understood as being the central mechanism that regulates macrophage function. Using macrophages of different origins and species, we report that macrophage elasticity is a major determinant of innate macrophage function. Macrophage elasticity is modulated not only by classical biologic activators such as LPS and IFN-γ, but to an equal extent by substrate rigidity and substrate stretch. Macrophage elasticity is dependent upon actin polymerization and small rhoGTPase activation, but functional effects of elasticity are not predicted by examination of gene expression profiles alone. Taken together, these data demonstrate an unanticipated role for cell elasticity as a common pathway by which mechanical and biologic factors determine macrophage function.

  16. Assessment of thoracic aortic elasticity: a preliminary study using electrocardiographically gated dual-source CT

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ning; Guo, Lijun; Sun, Haitao; Gao, Fei; Liu, Cheng [Shandong University, Shandong Medical Imaging Research Institute, Jinan (China); Beck, Thomas [Siemens AG, Healthcare Sector, Imaging and IT Division, Computed Tomography, Forchheim (Germany); Chen, Jiuhong [Siemens Ltd., China, Healthcare, No.7, Wangjing Zhonghuan Nanlu, Beijing (China); Biermann, Christina [Siemens AG, Siemens Healthcare Consulting, Erlangen (Germany)

    2011-07-15

    To gain a new insight into the elastic properties of the thoracic aorta in patients without aortic diseases using electrocardiographically (ECG)-gated dual-source (DS) CT. 56 subjects with no cardiovascular disease, selected from 2,700 people undergoing ECG-gated DSCT examination, were divided into three groups according to their age. CT data were reconstructed in 5% step throughout the RR interval. Diameter and area were measured at the curve of the ascending aorta (AA) and at the same level of the descending aorta (DA). The pulsation and elasticity of the aorta were evaluated. Aortic diameter changes were noted throughout the cardiac cycle. The maximum average diameter was seen at an RR interval of 24.02 {+-} 4.99% for the AA and 25.63 {+-} 4.77% for the DA. The minimum was at 93.5 {+-} 4.04% for the AA and 96.6 {+-} 4.58% for the DA. There was an age-dependent decrease in elasticity, while different correlation coefficients were found between various age groups and different elastic parameters. The properties of aortic pulsation and wall elasticity could be well shown by ECG-gated DSCT. The new findings regarding segment difference and age relevance were significant and should be taken into account in clinical trials and treatments for the elasticity related cardiovascular diseases. (orig.)

  17. Empirical processes with bounded \\psi_1 diameter

    CERN Document Server

    Mendelson, Shahar

    2010-01-01

    We study the empirical process indexed by F^2=\\{f^2 : f \\in F\\}, where F is a class of mean-zero functions on a probability space. We present a sharp bound on the supremum of that process which depends on the \\psi_1 diameter of the class F (rather than on the \\psi_2 one) and on the complexity parameter \\gamma_2(F,\\psi_2). In addition, we present optimal bounds on the random diameters \\sup_{f \\in F} \\max_{|I|=m} (\\sum_{i \\in I} f^2(X_i))^{1/2} using the same parameters. As applications, we extend several well known results in Asymptotic Geometric Analysis to any isotropic, log-concave ensemble on R^n.

  18. Transfinite diameter of Bernstein sets in

    Directory of Open Access Journals (Sweden)

    Bialas-Cież Leokadia

    2002-01-01

    Full Text Available Let be a compact set in satisfying the following generalized Bernstein inequality: for each such that , for each polynomial of degree where is a constant independent of and , is an infinite set of natural numbers that is also independent of and . We give an estimate for the transfinite diameter of the set : For satisfying the usual Bernstein inequality (i.e., , we prove that

  19. New Large Diameter RF Complex Plasma Device

    Science.gov (United States)

    Meyer, John; Nosenko, Volodymyr; Thomas, Hubertus

    2016-10-01

    The Complex Plasma Research Group at the German Aerospace Center (DLR) in Oberpfaffenhofen has built a new large diameter rf plasma setup for dusty plasma experiments. The vacuum chamber is a stainless steel cylinder 0.90 m in diameter and 0.34 m in height with ports for viewing and measurement. A 0.85 m diameter plate in about the center serves as a powered electrode (13.56 MHz) with the chamber walls as the ground. It is pumped on by one of two Oerlikon turbo pumps with a pumping rate of 1100 l/s or 270 l/s. Argon gas is admitted into the chamber by an MKS mass flow meter and pumping is regulated by a butterfly valve to set pressure for experiments. A manual dropper is used to insert dust into the plasma. The dust is illuminated horizontally by a 660 nm 100 mW laser sheet and viewed from above by a Photron FASTCAM 1024 PCI camera. A vertical laser sheet of 635 nm will be used for side imaging. So far, single-layer plasma crystals of up to 15000 particles have been suspended. The particle velocity fluctuation spectra were measured and from these, the particle charge and screening length were calculated. Future experiments will explore the system-size dependence of the plasma crystal properties.

  20. 29 mm Diameter Test Target Design Report

    Energy Technology Data Exchange (ETDEWEB)

    Woloshun, Keith Albert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Olivas, Eric Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Naranjo, Angela Carol [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Romero, Frank Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-15

    The Northstar target for Mo99 production is made up of Mo100 disks in a stack separated by coolant gaps for helium flow. A number of targets have been tested at ANL for both production of Mo99 and for thermal-hydraulic performance. These have all been with a 12 mm diameter target, even while the production goals have increased the diameter to now 29 mm. A 29 mm diameter target has been designed that is consistent with the ANL beam capabilities and the capabilities of the helium circulation system currently in use at ANL. This target is designed for 500 μA at 35 MeV electrons. While the plant design calls for 42 MeV, the chosen design point is more favorable and higher power given the limits of the ANL accelerator. The intended beam spot size is 12 mm FWHM, but the thermal analysis presented herein conservatively assumed a 10 mm FWHM beam, which results in a 44% higher beam current density at beam center.

  1. Hydrodynamic interaction between particles near elastic interfaces

    CERN Document Server

    Daddi-Moussa-Ider, Abdallah

    2016-01-01

    We present an analytical calculation of the hydrodynamic interaction between two spherical particles near an elastic interface such as a cell membrane. The theory predicts the frequency dependent self- and pair-mobilities accounting for the finite particle size up to the 5th order in the ratio between particle diameter and wall distance as well as between diameter and interparticle distance. We find that particle motion towards a membrane with pure bending resistance always leads to mutual repulsion similar as in the well-known case of a hard-wall. In the vicinity of a membrane with shearing resistance, however, we observe an attractive interaction in a certain parameter range which is in contrast to the behavior near a hard wall. This attraction might facilitate surface chemical reactions. Furthermore, we show that there exists a frequency range in which the pair-mobility for perpendicular motion exceeds its bulk value, leading to short-lived superdiffusive behavior. Using the analytical particle mobilities ...

  2. Limitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters

    Directory of Open Access Journals (Sweden)

    Robinson RA

    2013-05-01

    Full Text Available Ronald A Robinson, Luke H Herbertson, Srilekha Sarkar Das, Richard A Malinauskas, William F Pritchard, Laurence W GrossmanOffice of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD, USAAbstract: The purpose of this study was first to evaluate the clot capture efficiency and capture location of six currently-marketed vena cava filters in a physiological venous flow loop, using synthetic polyacrylamide hydrogel clots, which were intended to simulate actual blood clots. After observing a measured anomaly for one of the test filters, we redirected the focus of the study to identify the cause of poor clot capture performance for large synthetic hydrogel clots. We hypothesized that the uncharacteristic low clot capture efficiency observed when testing the outlying filter can be attributed to the inadvertent use of dense, stiff synthetic hydrogel clots, and not as a result of the filter design or filter orientation. To study this issue, sheep blood clots and polyacrylamide (PA synthetic clots were injected into a mock venous flow loop containing a clinical inferior vena cava (IVC filter, and their captures were observed. Testing was performed with clots of various diameters (3.2, 4.8, and 6.4 mm, length-to-diameter ratios (1:1, 3:1, 10:1, and stiffness. By adjusting the chemical formulation, PA clots were fabricated to be soft, moderately stiff, or stiff with elastic moduli of 805 ± 2, 1696 ± 10 and 3295 ± 37 Pa, respectively. In comparison, the elastic moduli for freshly prepared sheep blood clots were 1690 ± 360 Pa. The outlying filter had a design that was characterized by peripheral gaps (up to 14 mm between its wire struts. While a low clot capture rate was observed using large, stiff synthetic clots, the filter effectively captured similarly sized sheep blood clots and soft PA clots. Because the stiffer synthetic clots remained straight when approaching the

  3. Balance of microtubule stiffness and cortical tension determines the size of blood cells with marginal band across species

    CERN Document Server

    Dmitrieff, Serge; Mathur, Aastha; Nédélec, François

    2016-01-01

    The fast blood stream of animals is associated with large shear stresses. Consequently, blood cells have evolved a special morphology and a specific internal architecture allowing them to maintain their integrity over several weeks. For instance, non-mammalian red blood cells, mammalian erythroblasts and platelets have a peripheral ring of microtubules, called the marginal band, that flattens the overall cell morphology by pushing on the cell cortex. In this article, we model how the shape of these cells stems from the balance between marginal band elasticity and cortical tension. We predict that the diameter of the cell scales with the total microtubule polymer, and verify the predicted law across a wide range of species. Our analysis also shows that the combination of the marginal band rigidity and cortical tension increases the ability of the cell to withstand forces without deformation. Finally, we model the marginal band coiling that occurs during the disc-to-sphere transition observed for instance at th...

  4. Finned Small Diameter Tube Heat Exchanger

    Science.gov (United States)

    Dang, Chaobin; Daiguji, Hirofumi; Hihara, Eiji; Tokunaga, Masahide

    The performance of fined small tube heat exchangers was investigated both experimentally and theoretically. The Inner diameters of tubes were 1.0mm, 2.1mm and 4.0mm. Exchanged heat and pressure drop obtained from numerical simulation agreed well with the experimental ones. Calculation results show that the volume of a 2.0mm tube heat exchanger can be reduced to 33% of that of a 4mm tube heat exchanger with the same capacity. In addition the distribution of two-phase flow in a branching unit was investigated by measuring downstream temperature distribution. The flow distribution in a branching unit strongly affects the exchanged heat.

  5. Retrobulbar diameter of optic nerve in glaucoma

    Directory of Open Access Journals (Sweden)

    Stefanović Ivan

    2009-01-01

    Full Text Available Introduction. The ultrasound diagnostics of the optic nerve includes the analysis of the optic nerve disc (PNO and measuring of its retrobulbar diameter. With B-scan, by Schraeder's method, it is possible to measure very precisely the optic nerve, the pial diameter, the normal values for the pial diameter being 2.8-4.1 mm. In glaucoma, the disease that is most frequently associated with higher intraocular pressure, there comes the destruction of nerve fibres, which can be visualized as the excavation of the optic nerve disc. Objective. In this paper, we were interested in finding whether in glaucoma, and in what phase of the disease, the optic nerve starts growing thinner. Aware of many forms of this very complex disease, we were interested in knowing if the visualization of excavation on the optic nerve disc is related to diminishing of the pial diameter of the retrobulbar nerve part. Methods. There were treated the patients who had already had the diagnosis of glaucoma and the visualized excavation of the optic disc of various dimensions. Echographically, there was measured the thickness of the retrobulbar part of the optic nerve and the finding compared in relation to the excavation of the optic disc. Results. In all eyes with glaucoma, a normal size of the retrobulbar part of the optic nerve was measured, ranging from 3.01 to 3.91 mm with the median of 3.36 mm. Also, by testing the correlation between the thickness of the optic nerve and the excavation of the PNO, by Pearson test, we found that there was no correlation between these two parameters (r=0.109; p>0.05. Conclusion. In the patients with glaucoma, the retrobulbar part of the optic nerve is not thinner (it has normal values, even not in the cases with a totally excavated optic disc. There is no connection between the size of the PNO excavation and the thickness of the retrobulbar part of the optic nerve.

  6. Uniqueness theorems in linear elasticity

    CERN Document Server

    Knops, Robin John

    1971-01-01

    The classical result for uniqueness in elasticity theory is due to Kirchhoff. It states that the standard mixed boundary value problem for a homogeneous isotropic linear elastic material in equilibrium and occupying a bounded three-dimensional region of space possesses at most one solution in the classical sense, provided the Lame and shear moduli, A and J1 respectively, obey the inequalities (3 A + 2 J1) > 0 and J1>O. In linear elastodynamics the analogous result, due to Neumann, is that the initial-mixed boundary value problem possesses at most one solution provided the elastic moduli satisfy the same set of inequalities as in Kirchhoffs theorem. Most standard textbooks on the linear theory of elasticity mention only these two classical criteria for uniqueness and neglect altogether the abundant literature which has appeared since the original publications of Kirchhoff. To remedy this deficiency it seems appropriate to attempt a coherent description ofthe various contributions made to the study of uniquenes...

  7. Hilbert complexes of nonlinear elasticity

    Science.gov (United States)

    Angoshtari, Arzhang; Yavari, Arash

    2016-12-01

    We introduce some Hilbert complexes involving second-order tensors on flat compact manifolds with boundary that describe the kinematics and the kinetics of motion in nonlinear elasticity. We then use the general framework of Hilbert complexes to write Hodge-type and Helmholtz-type orthogonal decompositions for second-order tensors. As some applications of these decompositions in nonlinear elasticity, we study the strain compatibility equations of linear and nonlinear elasticity in the presence of Dirichlet boundary conditions and the existence of stress functions on non-contractible bodies. As an application of these Hilbert complexes in computational mechanics, we briefly discuss the derivation of a new class of mixed finite element methods for nonlinear elasticity.

  8. 冠心病合并高血压患者血压控制程度对动脉弹性功能的影响%The impact of blood pressure level on arterial elasticity in patients with coronary heart disease and hypertension

    Institute of Scientific and Technical Information of China (English)

    杨文; 王鸿懿; 孙宁玲

    2013-01-01

    目的 探讨冠心病合并高血压患者血压控制程度对动脉弹性功能的影响.方法 选择经过冠状动脉造影证实的冠心病合并高血压患者46例,全部患者均经过降压药物治疗.根据血压水平将患者分为2组,其中23例为血压控制不良组(收缩压≥140 mm Hg或舒张压≥90mmHg),另23例为血压控制良好组(收缩压< 140 mm Hg且舒张压<90 mm Hg)作为配对(1∶1).对2组患者血压、血管弹性功能[颈动脉-股动脉脉搏波速度(cfPWV),系统血管顺应性(SVC)、肱动脉扩张性(BAD)、系统血管阻力(SVR)]进行测定和分析.结果 (1)在血压控制良好组cfPWV(m/s)明显低于控制不良组(10.38±1.73比12.83±3.13,P<0.01).(2)血压控制良好组的SVC(ml/mm Hg)、BAD(%/mm Hg)与血压控制不良组相比增高(1.16±0.23比0.94±0.17,6.01±0.98比4.63±0.71,均为P<0.01).(3)cfPWV与年龄、收缩压、脉压正相关,相关系数r分别为0.374、0.416、0.507.多元线性逐步回归分析显示,cfPWV=4.796+0.099×脉压,即cfPWV与脉压成线性关系,提示收缩压及脉压增大加重患者的大动脉功能减退.结论 冠心病合并高血压患者存在血管弹性功能异常,并与血压控制不良直接相关.血压控制良好的患者SVC、BAD、cfPWV均有改善,冠心病合并高血压患者需要良好的血压控制.%Objective To explore the relationship of blood pressure level with the arterial elasticity in patients suffered from essential hypertension and coronary heart disease.Methods Fourty-six patients with essential hypertension and coronary heart disease were enrolled in.The coronary heart disease was diagnosed by coronary angiography.Patients were divided into two groups.One group was poor-controlled blood pressure group,whose SBP≥140 mm Hg and/or DBP≥90 mm Hg.The partnership group (1∶1)was well-controlled blood pressure group,which was defined as SBP < 140 mm Hg and DBP < 90 mm Hg.Arterial elasticity including [SVC (systemic

  9. DNA Bending elasticity

    Science.gov (United States)

    Sivak, David Alexander

    DNA bending elasticity on length scales of tens of basepairs is of critical importance in numerous biological contexts. Even the simplest models of DNA bending admit of few simple analytic results, thus there is a need for numerical methods to calculate experimental observables, such as distance distributions, forces, FRET efficiencies, and timescales of particular large-scale motions. We have implemented and helped develop a coarse-grained representation of DNA and various other covalently-linked groups that allows simple calculation of such observables for varied experimental systems. The simple freely-jointed chain (FJC) model and extremely coarse resolution proved useful in understanding DNA threading through nanopores, identifying steric occlusion by other parts of the chain as a prime culprit for slower capture as distance to the pore decreased. Enhanced sampling techniques of a finer resolution discrete wormlike chain (WLC) model permitted calculation of cyclization rates for small chains and identified the ramifications of a thermodynamically-sound treatment of thermal melts. Adding treatment of double-stranded DNA's helical nature and single-stranded DNA provided a model system that helped demonstrate the importance of statistical fluctuations in even highly-stressed DNA mini-loops, and allowed us to verify that even these constructs show no evidence of excitation-induced softening. Additional incorporation of salt-sensitivity to the model allowed us to calculate forces and FRET efficiencies for such mini-loops and their uncircularized precursors, thereby furthering the understanding of the nature of IHF binding and bending of its recognition sequence. Adding large volume-excluding spheres linked to the ends of the dsDNA permits calculation of distance distributions and thus small-angle X-ray scattering, whereby we demonstrated the validity of the WLC in describing bending fluctuations in DNA chains as short as 42 bp. We also make important connections

  10. Integrodifferential relations in linear elasticity

    CERN Document Server

    Kostin, Georgy V

    2012-01-01

    This work treats the elasticity of deformed bodies, including the resulting interior stresses and displacements.It also takes into account that some of constitutive relations can be considered in a weak form. To discuss this problem properly, the method of integrodifferential relations is used, and an advanced numerical technique for stress-strain analysis is presented and evaluated using various discretization techniques. The methods presented in this book are of importance for almost all elasticity problems in materials science and mechanical engineering.

  11. Electrodynamic forces in elastic matter

    OpenAIRE

    Antoci, S.; Mihich, L.

    1999-01-01

    A macroscopic theory for the dynamics of elastic, isotropic matter in presence of electromagnetic fields is proposed here. We avail of Gordon's general relativistic derivation of Abraham's electromagnetic energy tensor as starting point. The necessary description of the elastic and of the inertial behaviour of matter is provided through a four dimensional generalisation of Hooke's law, made possible by the introduction of a four dimensional ``displacement'' vector. As intimated by Nordstroem,...

  12. Longitudinal Mechanical Properties of Small-Diameter Polyurethane Vascular Graft Reinforced by Tubular Knitted Fabric

    Institute of Scientific and Technical Information of China (English)

    ZHOU Fei; XU Wei-lin; OUYANG Chen-xi; LIU Xiu-ying; XU Hai-ye; YAO Mu

    2008-01-01

    The vascular graft with 4 nun diameter was prepared by casting one layer of polyurethane (PU) film onto the knitting tubular fabric as the reinforced support. The effects of different PU content and wall thickness on the longitudinal mechanical properties of vascular graft were investigated. The breaking elongation, breaking force, initial modulus and breaking work were studied. The results showed that the longitudinal mechanical properties of vascular graft were enhanced as the content of polyurethane increased, which resulted from the combination of PU excellent elasticity and fabric preferable strength.

  13. Elastic Behavior of Polymer Chains

    Institute of Scientific and Technical Information of China (English)

    Teng Lu; Tao Chen; Hao-jun Liang

    2008-01-01

    The elastic behavior of the polymer chain was investigated in a three-dimensional off-lattice model. We sample more than 109 conformations of each kind of polymer chain by using a Monte Carlo algorithm, then analyze them with the non-Gaussian theory of rubberlike elasticity, and end with a statistical study. Through observing the effect of the chain flexibility and the stretching ratio on the mean-square end-to-end distance,the average energy, the average Helmholtz free energy, the elastic force, the contribution of energy to the elastic force, and the entropy contribution to elastic force of the polymer chain, we find that a rigid polymer chain is much easier to stretch than a flexible polymer chain. Also, a rigid polymer chain will become difficult to stretch only at a quite high stretching ratio because of the effect of the entropy contribution.These results of our simulation calculation may explain some of the macroscopic phenomena of polymer and biomacromolecular elasticity.

  14. Changes of blood pressure by dynamic arterial elastance in patients with hypovolemic shock after expansion%动态动脉弹性对低血容量性休克患者扩容后血压变化的影响

    Institute of Scientific and Technical Information of China (English)

    杨璇; 李长江; 冯磊; 延荣强; 李玉

    2014-01-01

    目的:探讨动态动脉弹性对低血容量性休克患者扩容后血压变化的影响。方法选择休克患者28例,根据快速扩容后患者平均动脉压( MAP)升高程度,分为研究组( MAP升高≥15﹪)和对照组( MAP升高﹤15﹪)。在快速扩容前后检测两组血流动力学指标,包括脉压变异度( PPV)、每搏变异度( SVV)、平均动脉压( MAP)、脉压( PP)、全心舒张末容积指数( GEDVI)、心输出量( CO)、每搏量指数( SVI)、全身血管阻力指数( SVRI)等,计算动脉弹性( Ea)、动态动脉弹性( Eadyn)并比较。结果两组的MAP、PP、SVI、CO、PPV、SVV、SVRI在扩容前后均有显著差异。扩容后,研究组MAP显著高于对照组,而Eadyn在扩容前于两组间就有统计学差异。逐步回归分析发现Eadyn是影响快速扩容前后MAP变化的重要因素。结论 Eadyn可较好地反映休克患者快速扩容后的血压反应性,值得临床参考应用。%Objective To investigate the influence of dynamic arterial elasticity on the changes of blood pressure in patients with hypov_olemic shock after expansion. Methods A total of 28 patients with shock were collected. According to the degree of mean arterial pressure ( MAP)increased after rapid expansion,the patients were divided into study group( MAP increased≥15﹪)and control group( MAP increased﹤15﹪). Hemodynamic parameters were detected and recorded before and after rapid expansion,including pulse pressure variability( PPV), stroke volume variability( SVV),MAP,pulse pressure( PP),global end-diastolic volume index( GEDVI),cardiac output( CO),stroke vol_ume index( SVI),systemic vascular resistance index( SVRI),etc. Arterial elasticity( Ea)and dynamic arterial elastance( Eadyn)were calcu_lated and compared. Results MAP,PP,SVI,CO,PPV,SVV and SVRI were significantly different before and after the expansion in both groups. After the expansion,MAP in the

  15. Measurement of Diameter Changes during Irradiation Testing

    Energy Technology Data Exchange (ETDEWEB)

    Davis, K. L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Knudson, D. L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Crepeau, J. C. [Univ. of Idaho, Idaho Falls, ID (United States); Solstad, S. [Inst. for Energy Technologoy, Halden (Norway)

    2015-03-01

    New materials are being considered for fuel, cladding, and structures in advanced and existing nuclear reactors. Such materials can experience significant dimensional and physical changes during irradiation. Currently in the US, such changes are measured by repeatedly irradiating a specimen for a specified period of time and then removing it from the reactor for evaluation. The time and labor to remove, examine, and return irradiated samples for each measurement makes this approach very expensive. In addition, such techniques provide limited data and handling may disturb the phenomena of interest. In-pile detection of changes in geometry is sorely needed to understand real-time behavior during irradiation testing of fuels and materials in high flux US Material and Test Reactors (MTRs). This paper presents development results of an advanced Linear Variable Differential Transformer-based test rig capable of detecting real-time changes in diameter of fuel rods or material samples during irradiation in US MTRs. This test rig is being developed at the Idaho National Laboratory and will provide experimenters with a unique capability to measure diameter changes associated with fuel and cladding swelling, pellet-clad interaction, and crud buildup.

  16. Case Study: Effect of Handrim Diameter on Performance in a Paralympic Wheelchair Athlete

    Science.gov (United States)

    Costa, Gabriel Brizuela; Rubio, Miguel Polo; Belloch, Salvador Llana; Soriano, Pedro Perez

    2009-01-01

    This study, with a top T-52 class athlete, determines the relationship between stroke frequency (SF) and push time (PT) and wheelchair velocity (Wv) using different handrim diameters (HD) and the effect of different HDs on the athlete's heart rate (HR) and blood lactate (LACT) at competition speeds. Wv shows a linear-direct relationship with SF…

  17. Mature red blood cells: from optical model to inverse light-scattering problem.

    Science.gov (United States)

    Gilev, Konstantin V; Yurkin, Maxim A; Chernyshova, Ekaterina S; Strokotov, Dmitry I; Chernyshev, Andrei V; Maltsev, Valeri P

    2016-04-01

    We propose a method for characterization of mature red blood cells (RBCs) morphology, based on measurement of light-scattering patterns (LSPs) of individual RBCs with the scanning flow cytometer and on solution of the inverse light-scattering (ILS) problem for each LSP. We considered a RBC shape model, corresponding to the minimal bending energy of the membrane with isotropic elasticity, and constructed an analytical approximation, which allows rapid simulation of the shape, given the diameter and minimal and maximal thicknesses. The ILS problem was solved by the nearest-neighbor interpolation using a preliminary calculated database of 250,000 theoretical LSPs. For each RBC in blood sample we determined three abovementioned shape characteristics and refractive index, which also allows us to calculate volume, surface area, sphericity index, spontaneous curvature, hemoglobin concentration and content.

  18. Elastic-plastic deformation of sandwich rod on elastic basis

    Institute of Scientific and Technical Information of China (English)

    GU Yu

    2008-01-01

    Sandwich composite material possesses advantages of both light weight and high strength.Although the mechanical behaviors of sandwich composite material with the influence of single external environment have been intensively studied,little work has been done in the study of mechanical property,in view of the nonlinear behavior of sandwich composites in the complicated external environments.In this paper,the problem about the bending of the three-layer elastic-plastic rod located on the elastic base,with a compressibly physical nonlinear core,has been studied.The mechanical response of the designed three-layer elements consisting of two bearing layers and a core has been examined.The complicated problem about curving of the three-layer rod located on the elastic base has been solved.The convergence of the proposed method of elastic solutions is examined to convince that the solution is acceptable.The calculated results indicate that the plasticity and physical nonlinearity of materials have a great influence on the deformation of the sandwich rod on the elastic basis.

  19. Elastic fibers and collagen distribution in human aorta

    Science.gov (United States)

    Vieira-Damiani, G.; Ferro, D. P.; Adam, R. L.; de Thomaz, A. A.; Pelegati, V.; Cesar, C. L.; Metze, K.

    2011-03-01

    Elastic and collagen fibers are essential components of the aorta, the remodeling of these structures is accompanied with aging in various diseases and life-threatening events. While the elastic fibers confer resilience to major blood vessels collagen confers resistance to the same. Elastic fibers are easily visualized in the fluorescent light when stained with hematoxylin eosin. Second Harmonic Generation (SHG) is a non linear signal that occurs only in molecules without inversion symmetry and is particularly strong in the collagen fibers arranged in triple helices. The aim of this paper is to describe the distribution of collagen in the thickness of the thoracic aorta, and to demonstrate the distribution of between elastic fibers. The images were acquired in a multifoton microscopy and both signals, Two-phtoton excitaded fluorescence (TPEF) and SHG, were excited by a Ti:Sapphire laser. We used a band pass filter to filter the SHG signal from the TPEF signal. The thickness of the aorta varies 2-3 mm, and the image was composed of the juxtaposition of images of 220 x 220 microns. We acquired images of a histological slide of the thoracic aorta stained with picrosirius red (specific for collagen) at a wavelength of 670nm SHG subsequently acquired images with the same region and observed that the images are overlapping. Therefore, the following images were acquired by confocal microscopy (fluorescence of eosin for visualization of elastic fibers) and for collagen SHG. After reconstruction of the images, we observed the distribution of collagen along the aorta.

  20. Fire protection covering for small diameter missiles

    Science.gov (United States)

    Riccitiello, S. R.; Sawko, P. M. (Inventor)

    1979-01-01

    Flexible intumescent protection sheeting of unusually uniform thickness were prepared from epoxy-polysulfide compositions, containing microfibers and the ammonium salt of 1,4-nitroaniline-2-sulfonic acid, as disclosed in U.S. Pat. No. 3,663,464, except that an ammonium salt particle size in the order of 5 to 8 microns and a fiber size of about 1/128th inch in length and 3 to 5 microns in diameter were found critical to obtain the required density of 1.46 to 1.50 g/cc. The insulation sheeting was prepared by a continuous process involving vacuum mixing, calendering, and curing under very strict conditions which depend to some extent upon the thickness of the sheet produced.

  1. Lattice BGK simulations of unsteady flow in a 2D elastic tube

    NARCIS (Netherlands)

    Hoekstra, A.G.; van 't Hoff, J.; Artoli, A.M.M.; Sloot, P.M.A.

    2003-01-01

    We report results of unsteady, harmonic flow simulations with the lattice BGK method in two-dimensional elastic tubes. The tubes are assumed to obey a simple constitutive equation, linearly relating the diameter of the tube to the pressure difference inside and outside the tube. First, as a benchmar

  2. Effect of temperature and geometric parameters on elastic properties of tungsten nanowire: A molecular dynamics study

    Science.gov (United States)

    Saha, Sourav; Mojumder, Satyajit; Mahboob, Monon; Islam, M. Zahabul

    2016-07-01

    Tungsten is a promising material and has potential use as battery anode. Tungsten nanowires are gaining attention from researchers all over the world for this wide field of application. In this paper, we investigated effect of temperature and geometric parameters (diameter and aspect ratio) on elastic properties of Tungsten nanowire. Aspect ratios (length to diameter ratio) considered are 8:1, 10:1, and 12:1 while diameter of the nanowire is varied from 1-4 nm. For 2 nm diameter sample (aspect ratio 10:1), temperature is varied (10K ~ 1500K) to observe elastic behavior of Tungsten nanowire under uniaxial tensile loading. EAM potential is used for molecular dynamic simulation. We applied constant strain rate of 109 s-1 to deform the nanowire. Elastic behavior is expressed through stress vs. strain plot. We also investigated the fracture mechanism of tungsten nanowire and radial distribution function. Investigation suggests peculiar behavior of Tungsten nanowire in nano-scale with double peaks in stress vs. strain diagram. Necking before final fracture suggests that actual elastic behavior of the material is successfully captured through atomistic modeling.

  3. Thermal stiffening of clamped elastic ribbons

    Science.gov (United States)

    Wan, Duanduan; Nelson, David R.; Bowick, Mark J.

    2017-07-01

    We use molecular dynamics to study the vibrations of a thermally fluctuating two-dimensional elastic membrane clamped at both ends. We directly extract the eigenmodes from resonant peaks in the frequency domain of the time-dependent height and measure the dependence of the corresponding eigenfrequencies on the microscopic bending rigidity of the membrane, taking care also of the subtle role of thermal contraction in generating a tension when the projected area is fixed. At finite temperatures we show that the effective (macroscopic) bending rigidity tends to a constant as the bare bending rigidity vanishes, consistent with theoretical arguments that the large-scale bending rigidity of the membrane arises from a strong thermal renormalization of the microscopic bending rigidity. Experimental realizations include covalently bonded two-dimensional atomically thin membranes such as graphene and molybdenum disulfide or soft matter systems such as the spectrin skeleton of red blood cells or diblock copolymers.

  4. 隐蔽性高血压患者中心动脉压及增强指数与动脉弹性的相关性%Relationship between central blood pressure and its reflected wave with arterial elasticity in masked hypertensive patients

    Institute of Scientific and Technical Information of China (English)

    胡小亮; 路方红; 刘振东; 赵颖馨; 孙尚文; 王舒健; 李俊

    2011-01-01

    目的 探讨隐蔽性高血压患者中心动脉压及增强指数与动脉弹性的关系.方法 选择临床诊断血压正常者360例及高血压患者100例监测24 h动态血压,根据监测结果将受试者分为隐蔽性高血压组(n=135)、血压正常组(n=225)及高血压组(n=100).应用大动脉测量仪测量中心动脉压及其反射波;应用脉搏波传导速度测定仪测定颈桡动脉脉搏波传导速度(crPWV).结果 隐蔽性高血压组中心动脉收缩压(CSP)、舒张压(CDP)、中心脉压(CPP)、平均收缩压(CMSP)、平均舒张压(CMDP)、收缩末压(CESP)、增强压(AUG)、crPWV均高于血压正常组,低于高血压组(P<0.01或P<0.05).校正性别和年龄后,多元线性回归分析显示CSP、CPP、总胆固醇是crPWV的影响因素(B值分别为0.043,0.085,0.792;均P<0.01).结论 隐蔽性高血压患者动脉粥样硬化和中心动脉压相关,CSP和CPP是影响动脉硬化程度的独立危险因素.%Objective To investigate if central blood pressure and its reflected wave augmentation index are associated with arterial elasticity in masked hypertensives. Methods Three hundred sixty adults normotensives (office blood pressureblood pressure 2&140/90 mm Hg or receiving antihy-pertension medications) underwent 24 h ambulatory blood pressure monitoring. Based on the blood pressure, all the patients were categorized into masked hypertensives (n=135) , normotensives (n=225) and hypertensives (n = 100) respectively. Central blood pressure and its reflected wave were measured noninvasively with SphygmoCor device, and carotid-radial pulse wave velocity (crPWV) was detected by Complior. Results Central systolic pressure (CSP), central diastolic pressure (CDP), central pulse pressure (CPP), central mean systolic (CMSP), central mean diastolic (CMDP), central end systolic pressure (CESP), PI Height, augmentation pressure (AUG) and the values of crPWV were higher in masked

  5. Buckling modes of elastic thin films on elastic substrates

    Science.gov (United States)

    Mei, Haixia; Huang, Rui; Chung, Jun Young; Stafford, Christopher M.; Yu, Hong-Hui

    2007-04-01

    Two buckling modes have been observed in thin films: buckle delamination and wrinkling. This letter identifies the conditions for selecting the favored buckling modes for elastic films on elastic substrates. Transition from one buckling mode to another is predicted as the stiffness ratio between the substrate and the film or is predicted for variation of the stiffness ratio between the substrate and the film or variation of theinterfacial defect size. The theoretical results are demonstrated experimentally by observing the coexistence of both buckling modes and mode transition in one film-substrate system.

  6. Fatigue acceptance test limit criterion for larger diameter rolled thread fasteners

    Energy Technology Data Exchange (ETDEWEB)

    Kephart, A.R.

    1997-05-01

    This document describes a fatigue lifetime acceptance test criterion by which studs having rolled threads, larger than 1.0 inches in diameter, can be assured to meet minimum quality attributes associated with a controlled rolling process. This criterion is derived from a stress dependent, room temperature air fatigue database for test studs having a 0.625 inch diameter threads of Alloys X-750 HTH and direct aged 625. Anticipated fatigue lives of larger threads are based on thread root elastic stress concentration factors which increase with increasing thread diameters. Over the thread size range of interest, a 30% increase in notch stress is equivalent to a factor of five (5X) reduction in fatigue life. The resulting diameter dependent fatigue acceptance criterion is normalized to the aerospace rolled thread acceptance standards for a 1.0 inch diameter, 0.125 inch pitch, Unified National thread with a controlled Root radius (UNR). Testing was conducted at a stress of 50% of the minimum specified material ultimate strength, 80 Ksi, and at a stress ratio (R) of 0.10. Limited test data for fastener diameters of 1.00 to 2.25 inches are compared to the acceptance criterion. Sensitivity of fatigue life of threads to test nut geometry variables was also shown to be dependent on notch stress conditions. Bearing surface concavity of the compression nuts and thread flank contact mismatch conditions can significantly affect the fastener fatigue life. Without improved controls these conditions could potentially provide misleading acceptance data. Alternate test nut geometry features are described and implemented in the rolled thread stud specification, MIL-DTL-24789(SH), to mitigate the potential effects on fatigue acceptance data.

  7. Photoacoustic elastic oscillation and characterization.

    Science.gov (United States)

    Gao, Fei; Feng, Xiaohua; Zheng, Yuanjin

    2015-08-10

    Photoacoustic imaging and sensing have been studied extensively to probe the optical absorption of biological tissue in multiple scales ranging from large organs to small molecules. However, its elastic oscillation characterization is rarely studied and has been an untapped area to be explored. In literature, photoacoustic signal induced by pulsed laser is commonly modelled as a bipolar "N-shape" pulse from an optical absorber. In this paper, the photoacoustic damped oscillation is predicted and modelled by an equivalent mass-spring system by treating the optical absorber as an elastic oscillator. The photoacoustic simulation incorporating the proposed oscillation model shows better agreement with the measured signal from an elastic phantom, than conventional photoacoustic simulation model. More interestingly, the photoacoustic damping oscillation effect could potentially be a useful characterization approach to evaluate biological tissue's mechanical properties in terms of relaxation time, peak number and ratio beyond optical absorption only, which is experimentally demonstrated in this paper.

  8. Elastic actuation for legged locomotion

    Science.gov (United States)

    Cao, Chongjing; Conn, Andrew

    2017-04-01

    The inherent elasticity of dielectric elastomer actuators (DEAs) gives this technology great potential in energy efficient locomotion applications. In this work, a modular double cone DEA is developed with reduced manufacturing and maintenance time costs. This actuator can lift 45 g of mass (5 times its own weight) while producing a stroke of 10.4 mm (23.6% its height). The contribution of the elastic energy stored in antagonistic DEA membranes to the mechanical work output is experimentally investigated by adding delay into the DEA driving voltage. Increasing the delay time in actuation voltage and hence reducing the duty cycle is found to increase the amount of elastic energy being recovered but an upper limit is also noticed. The DEA is then applied to a three-segment leg that is able to move up and down by 17.9 mm (9% its initial height), which demonstrates the feasibility of utilizing this DEA design in legged locomotion.

  9. Photoacoustic elastic oscillation and characterization

    CERN Document Server

    Gao, Fei; Zheng, Yuanjin

    2014-01-01

    Photoacoustic imaging and sensing have been studied extensively to probe the optical absorption of biological tissue in multiple scales ranging from large organs to small molecules. However, its elastic oscillation characterization is rarely studied and has been an untapped area to be explored. In literature, photoacoustic signal induced by pulsed laser is commonly modelled as a bipolar "N-shape" pulse from an optical absorber. In this paper, the photoacoustic damped oscillation is predicted and modelled by an equivalent mass-spring system by treating the optical absorber as an elastic oscillator. The photoacoustic simulation incorporating the proposed oscillation model shows better agreement with the measured signal from an elastic phantom, than conventional photoacoustic simulation model. More interestingly, the photoacoustic damping oscillation effect could potentially be a useful characterization approach to evaluate biological tissue's mechanical properties in terms of relaxation time, peak number and ra...

  10. Blood Types

    Science.gov (United States)

    ... blood, safe blood transfusions depend on careful blood typing and cross-matching. The ABO Blood Group System ... that provided by the ABO positive/negative blood typing. For example, sometimes if the donor and recipient ...

  11. Dynamics of Elastic Excitable Media

    CERN Document Server

    Cartwright, J H E; Hernández-García, E; Piro, O; Cartwright, Julyan H. E.; Eguiluz, Victor M.; Hernandez-Garcia, Emilio; Piro, Oreste

    1999-01-01

    The Burridge-Knopoff model of earthquake faults with viscous friction is equivalent to a van der Pol-FitzHugh-Nagumo model for excitable media with elastic coupling. The lubricated creep-slip friction law we use in the Burridge-Knopoff model describes the frictional sliding dynamics of a range of real materials. Low-dimensional structures including synchronized oscillations and propagating fronts are dominant, in agreement with the results of laboratory friction experiments. Here we explore the dynamics of fronts in elastic excitable media.

  12. Complex variable methods in elasticity

    CERN Document Server

    England, A H

    2003-01-01

    The plane strain and generalized plane stress boundary value problems of linear elasticity are the focus of this graduate-level text, which formulates and solves these problems by employing complex variable theory. The text presents detailed descriptions of the three basic methods that rely on series representation, Cauchy integral representation, and the solution via continuation. Its five-part treatment covers functions of a complex variable, the basic equations of two-dimensional elasticity, plane and half-plane problems, regions with circular boundaries, and regions with curvilinear bounda

  13. LED-based digital diameter measurement

    Science.gov (United States)

    Kleuver, Wolfram; Becker, Lothar

    1995-01-01

    This paper presents a new industrial sensor for measuring diameters of extreme thin objects. The system is divided in two parts. The first is the emitter and the second the receiver. It is possible to use this system for the automatic inspection of files and wires in the textile industries and wire works. Another application for the sensor is the control of production of chemical files in an extruder. Furthermore we can measure more than one object in the lightbeam because we get information not only about the dimensions also about the position of the objects in the beam. The innovation in this system is the using of a light emitting diode (LED) as emitter and the realization of a long distance of about two or more meters between the two sensorheads. The results of this development are a special kind of optical layout in the emitter to reduce the loss of intensity and minimize the divergence of the lightbeam. It is not necessary to develop an intensity distribution, which is equal over the complete width of the sensorhead. We can show that we have a better dynamic in the system with this feature. The experiments prove that we get the same resolution as a laserbeamsensor. Furthermore one advantage is the eye-safety.

  14. A comprehensive comparison on vibration and heat transfer of two elastic heat transfer tube bundles

    Institute of Scientific and Technical Information of China (English)

    闫柯; 葛培琪; 翟强

    2015-01-01

    Elastic heat transfer tube bundles are widely used in the field of flow-induced vibration heat transfer enhancement. Two types of mainly used tube bundles, the planar elastic tube bundle and the conical spiral tube bundle were comprehensively compared in the condition of the same shell side diameter. The natural mode characteristics, the effect of fluid−structure interaction, the stress distribution, the comprehensive heat transfer performance and the secondary fluid flow of the two elastic tube bundles were all concluded and compared. The results show that the natural frequency and the critical velocity of vibration buckling of the planar elastic tube bundle are larger than those of the conical spiral tube bundle, while the stress distribution and the comprehensive heat transfer performance of the conical spiral tube bundle are relatively better.

  15. Elastic friction drive of surface acoustic wave motor.

    Science.gov (United States)

    Kurosawa, Minoru Kuribayashi; Itoh, Hidenori; Asai, Katsuhiko

    2003-06-01

    Importance of elastic deformation control to obtain large output force with a surface acoustic wave (SAW) motor is discussed in this paper. By adding pre-load to slider, stator and slider surfaces are deformed in a few tens nanometer. Appropriate deformation in normal direction against normal vibration displacement amplitude of SAW existed. By moderate deformation, the output force of the SAW motor was enlarged up to about 10 N and no-load speed was 0.7 m/s. To produce this performance, the transducer weight and slider size were only 4.2 g and 4 x 4 mm(2).By traveling wave propagation, surface particles of the SAW device move in elliptical motion. Due to the amplitude of the elliptical motion is 10 or 20 nm order, the contact condition of the slider is very critical. To control the contact condition, namely, the elastic deformation of the slider and stator surface in nanometer order, a lot of projections were fabricated on the slider surface. The projection diameter was 20 micro m. In static condition, the elastic deformation and stress were evaluated with the FEM analysis. From this calculation and the simulation result, it is consider that the wave crest is distorted, hence the elasticity has influence on the friction drive condition. Elastic deformation of the stator surface beneath the projection from the initial position were evaluated. In 4 x 4 mm(2) square area, the sliders had from 1089 to 23,409 projections. Depression was independent to the contact pressure. However, the output force depended on the depression although the projection density were different. From the view point of the output power of the motor, the proper depression was independent to the projection density. Around 25 nm depression, the output force and output power were maximized. This depression value was almost same as the vibration displacement amplitude of the stator transducer.

  16. Predicting dynamics and rheology of blood flow: A comparative study of multiscale and low-dimensional models of red blood cells.

    Science.gov (United States)

    Pan, Wenxiao; Fedosov, Dmitry A; Caswell, Bruce; Karniadakis, George Em

    2011-09-01

    We compare the predictive capability of two mathematical models for red blood cells (RBCs) focusing on blood flow in capillaries and arterioles. Both RBC models as well as their corresponding blood flows are based on the dissipative particle dynamics (DPD) method, a coarse-grained molecular dynamics approach. The first model employs a multiscale description of the RBC (MS-RBC), with its membrane represented by hundreds or even thousands of DPD-particles connected by springs into a triangular network in combination with out-of-plane elastic bending resistance. Extra dissipation within the network accounts for membrane viscosity, while the characteristic biconcave RBC shape is achieved by imposition of constraints for constant membrane area and constant cell volume. The second model is based on a low-dimensional description (LD-RBC) constructed as a closed torus-like ring of only 10 large DPD colloidal particles. They are connected into a ring by worm-like chain (WLC) springs combined with bending resistance. The LD-RBC model can be fitted to represent the entire range of nonlinear elastic deformations as measured by optical-tweezers for healthy and for infected RBCs in malaria. MS-RBCs suspensions model the dynamics and rheology of blood flow accurately for any vessel size but this approach is computationally expensive for vessel diameters above 100μm. Surprisingly, the much more economical suspensions of LD-RBCs also capture the blood flow dynamics and rheology accurately except for small-size vessels comparable to RBC diameter. In particular, the LD-RBC suspensions are shown to properly capture the experimental data for the apparent viscosity of blood and its cell-free layer (CFL) in tube flow. Taken together, these findings suggest a hierarchical approach in modeling blood flow in the arterial tree, whereby the MS-RBC model should be employed for capillaries and arterioles below 100μm, the LD-RBC model for arterioles, and the continuum description for arteries.

  17. Mockup Small-Diameter Air Distribution System

    Energy Technology Data Exchange (ETDEWEB)

    A. Poerschke and A. Rudd

    2016-05-01

    This report investigates the feasibility of using a home-run manifold small-diameter duct system to provide space conditioning air to individual thermal zones in a low-load home. This compact layout allows duct systems to be brought easily within conditioned space via interior partition walls. Centrally locating the air hander unit in the house significantly reduces duct lengths. The plenum box is designed so that each connected duct receives an equal amount of airflow, regardless of the duct position on the box. Furthermore, within a reasonable set of length restrictions, each duct continues to receive similar airflow. The design method uses an additive approach to reach the total needed zonal airflow. Once the cubic feet per minute needed to satisfy the thermal load of a zone has been determined, the total number of duct runs to a zone can be calculated by dividing the required airflow by the standard airflow from each duct. The additive approach greatly simplifies the design effort and reduces the potential for duct design mistakes to be made. Measured results indicate that this plenum design can satisfy the heating load. However, the total airflow falls short of satisfying the cooling load in a hypothetical building. Static pressure inside the plenum box of 51.5 Pa limited the total airflow of the attached mini-split heat pump blower, thus limiting the total thermal capacity. Fan energy consumption is kept to 0.16 to 0.22 watt/CFM by using short duct runs and smooth duct material.

  18. Structure and function of the elastic organ in the tibia of a tenebrionid beetle

    Science.gov (United States)

    Ichikawa, Toshio; Toh, Yoshihiro; Sakamoto, Hirofumi

    2016-06-01

    Many insects have a pair of claws on the tip of each foot (tarsus and pretarsus). The movement of the pretarsal claws is mediated by a long apodeme that originates from the claw retractor muscles in the femur. It is generally accepted that the pulling of the apodeme by the muscles flexes the claws to engage with a rough surface of a substrate, and the flexed claws return to their initial position by passive elastic forces within the tarso-pretarsal joint. We found that each tibia of the tenebrionid beetle Zophobas atratus had a chordal elastic organ that tied the apodeme to the distal end of the tibia and assisted the pulled apodeme to return smoothly. The elastic body of the elastic organ consists of a bundle of more than 1000 thin fibrils (0.3-1.5 μm in diameter) with a hairy yarn-shaped structure made by assemblies of intricately interwoven microfibers. Both ends of the fibrillar elastic body were supported by clusters of columnar cells. Ablation of the elastic organ often disturbed the rapid and smooth return of claws from a flexed position when the tarsal segments were forced to curve in order to increase the friction between the apodeme and surrounding tissues in the segments. The result suggests that rapid claw disengagement is an important step in each cycle of leg movements, and the elastic organ may have evolved to assist the reliable detachment of claws that engage tightly with the substrate when climbing or traversing inverted surfaces.

  19. Pilot Study of Debt Elasticity

    Science.gov (United States)

    Greiner, Keith; Girardi, Tony

    2006-01-01

    This report examines the relationship between student loan debt and the manner in which that debt is described. It focuses on three forms of description: (1) monthly payments, (2) total debt, and (3) income after graduation. The authors used the term elasticity to describe the relationship between consumers' college choices and the retention…

  20. The Quality Assessment of Stored Red Blood Cells Probed Using Atomic-Force Microscopy

    Directory of Open Access Journals (Sweden)

    I. M. Lamzin

    2014-01-01

    Full Text Available At the moment the suitability of stored red blood cells (sRBC for transfusion is checked by routine methods such as haemoglobin estimation and the level of haemolysis. These methods cannot characterize directly the quality of the membranes of sRBC. The aim of this work is to assess the quality of sRBC based on such criteria as the membrane’s stiffness and the size and the form of sRBC. Materials and Methods. We have investigated 5 series of dry cytosmears of the sRBC which had been kept in blood bank in a period from 1 to 35 days. After AFM imaging, in every specimen, 5 RBC were chosen at random; the diameter, the height, and the stiffness were measured on each of them. Results. The present study shows high increase of the mean values of YM and height of RBC after 35 days of storage and decrease of the mean values of their diameter. Conclusion. Statistically significant high increase of the mean values of YM indicates the decrease of the elasticity of the cells in the course of storing of the RBC. This parameter along with the morphological characteristics can be used as criterion for assessment of applicability of the sRBC for blood transfusion.

  1. The quality assessment of stored red blood cells probed using atomic-force microscopy.

    Science.gov (United States)

    Lamzin, I M; Khayrullin, R M

    2014-01-01

    At the moment the suitability of stored red blood cells (sRBC) for transfusion is checked by routine methods such as haemoglobin estimation and the level of haemolysis. These methods cannot characterize directly the quality of the membranes of sRBC. The aim of this work is to assess the quality of sRBC based on such criteria as the membrane's stiffness and the size and the form of sRBC. Materials and Methods. We have investigated 5 series of dry cytosmears of the sRBC which had been kept in blood bank in a period from 1 to 35 days. After AFM imaging, in every specimen, 5 RBC were chosen at random; the diameter, the height, and the stiffness were measured on each of them. Results. The present study shows high increase of the mean values of YM and height of RBC after 35 days of storage and decrease of the mean values of their diameter. Conclusion. Statistically significant high increase of the mean values of YM indicates the decrease of the elasticity of the cells in the course of storing of the RBC. This parameter along with the morphological characteristics can be used as criterion for assessment of applicability of the sRBC for blood transfusion.

  2. Body diameters in 3 - 6 years old children from Plovdiv

    Directory of Open Access Journals (Sweden)

    Tineshev Slavi

    2013-01-01

    Full Text Available The purpose of the research is to analyze the body diameters in 3-6 year old children. The biacromial diameters were taken as well as the two chest diameters, the bicristal and bitrohanterial diameters in 316 children (157 boys and 159 girls 3, 4, 5 and 6 years of age attending kindergarten in Plovdiv. The analysis shows that all diameters, with the exception of the bitrohanterial have higher values in boys. The absolute year's increment of the diameters is greater in girls. The growth velocity of the researched features is greatest at the age of 3-4 and 4-5, decreasing at different rates for the different features at the age of 5-6. The only exception is the sagittal chest diameter in both sexes and the bitrohanterial diameters in girls.

  3. ANALYSIS OF PULSATILE BLOOD FLOW IN AXIALLY MOVING ARTERIES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

  4. Heart transplantation and arterial elasticity

    Directory of Open Access Journals (Sweden)

    Colvin-Adams M

    2013-12-01

    Full Text Available Monica Colvin-Adams,1 Nonyelum Harcourt,1 Robert LeDuc,2 Ganesh Raveendran,1 Yassir Sonbol,3 Robert Wilson,1 Daniel Duprez11Cardiovascular Division, University of Minnesota, Minneapolis, MN, USA; 2Division of Biostatistics University of Minnesota, Minneapolis, MN, USA; 3Cardiovascular Division, St Luke's Hospital System, Sugar Land, TX, USAObjective: Arterial elasticity is a functional biomarker that has predictive value for cardiovascular morbidity and mortality in nontransplant populations. There is little information regarding arterial elasticity in heart transplant recipients. This study aimed to characterize small (SAE and large (LAE artery elasticity in heart transplant recipients in comparison with an asymptomatic population free of overt cardiovascular disease. A second goal was to identify demographic and clinical factors associated with arterial elasticity in this unique population.Methods: Arterial pulse waveform was registered noninvasively at the radial artery in 71 heart transplant recipients between 2008 and 2010. SAEs and LAEs were derived from diastolic pulse contour analysis. Comparisons were made to a healthy cohort of 1,808 participants selected from our prevention clinic database. Multiple regression analyses were performed to evaluate associations between risk factors and SAE and LAE within the heart transplant recipients.Results: LAE and SAE were significantly lower in heart transplant recipients than in the normal cohort (P <0.01 and P < 0.0001, respectively. Female sex and history of ischemic cardiomyopathy were significantly associated with reduced LAE and SAE. Older age and the presence of moderate cardiac allograft vasculopathy were also significantly associated with reduced SAE. Transplant duration was associated with increased SAE.Conclusion: Heart transplants are associated with peripheral endothelial dysfunction and arterial stiffness, as demonstrated by a significant reduction in SAE and LAE when compared with a

  5. Numerical Simulation of Large Diameter Cylindrical Structure Slamming

    Institute of Scientific and Technical Information of China (English)

    XU Jing; WANG De-yu

    2008-01-01

    The water entry of large diameter cylindrical structure is studied by applying numerical simulation method. The processes of different diameter cylindrical structures impacting water with various constant velocities are calculated numerically. Thereafter, analyzed are the distribution of slamming pressure on structure during slamming course and the influence of slamming velocity and cylindrical diameter on slamming process. Furthermore, presented herein is an equation being used to forecast the peak slamming force on a large diameter cylindrical structure.

  6. Thermodynamic parameters of elasticity and electrical conductivity ...

    African Journals Online (AJOL)

    Thermodynamic parameters of elasticity and electrical conductivity of reinforced natural rubber (nr) vulca nizates. ... Bulletin of the Chemical Society of Ethiopia ... The thermodynamic parameters (change in free energy of elasticity, DGe; ...

  7. The diameter-dependent photoelectrochemical performance of silicon nanowires.

    Science.gov (United States)

    Zhang, Bing-Chang; Wang, Hui; He, Le; Duan, Chun-Yang; Li, Fan; Ou, Xue-Mei; Sun, Bao-Quan; Zhang, Xiao-Hong

    2016-01-25

    We demonstrate the first systematic study of the diameter-dependent photoelectrochemical performance of single silicon nanowires within a broad size range from 200 to 2000 nm. SiNWs with a diameter of 1415 nm exhibit the highest solar energy conversion efficiency, which can be mainly traced to their diameter-dependent light absorption properties.

  8. Elastic properties and electron transport in InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Migunov, Vadim

    2013-02-22

    The electron transport and elastic properties of InAs nanowires grown by chemical vapor deposition on InAs (001) substrate were studied experimentally, in-situ in a transmission electron microscope (TEM). A TEM holder allowing the measurement of a nanoforce while simultaneous imaging nanowire bending was used. Diffraction images from local areas of the wire were recorded to correlate elastic properties with the atomic structure of the nanowires. Another TEM holder allowing the application of electrical bias between the nanowire and an apex of a metallic needle while simultaneous imaging the nanowire in TEM or performing electron holography was used to detect mechanical vibrations in mechanical study or holographical observation of the nanowire inner potential in the electron transport studies. The combination of the scanning probe methods with TEM allows to correlate the measured electric and elastic properties of the nanowires with direct identification of their atomic structure. It was found that the nanowires have different atomic structures and different stacking fault defect densities that impacts critically on the elastic properties and electric transport. The unique methods, that were applied in this work, allowed to obtain dependencies of resistivity and Young's modulus of left angle 111 right angle -oriented InAs nanowires on defect density and diameter. It was found that the higher is the defect density the higher are the resistivity and the Young's modulus. Regarding the resistivity, it was deduced that the stacking faults increase the scattering of the electrons in the nanowire. These findings are consistent with the literature, however, the effect described by the other groups is not so pronounced. This difference can be attributed to the significant incompleteness of the physical models used for the data analysis. Regarding the elastic modulus, there are several mechanisms affecting the elasticity of the nanowires discussed in the thesis. It

  9. Impact of pubertal development on endothelial function and arterial elasticity.

    Science.gov (United States)

    Marlatt, Kara L; Steinberger, Julia; Dengel, Donald R; Sinaiko, Alan; Moran, Antoinette; Chow, Lisa S; Steffen, Lyn M; Zhou, Xia; Kelly, Aaron S

    2013-11-01

    Little is known about the relation of pubertal development on endothelial function and arterial elasticity in children and adolescents; therefore, we compared brachial artery flow-mediated dilation and carotid artery elasticity across Tanner (pubertal) stages in children and adolescents. Blood pressure, fasting lipids, glucose and insulin, body fat, insulin sensitivity adjusted for lean body mass, brachial flow-mediated dilation (percent dilation and area under the curve), endothelium-independent dilation (peak dilation and area under the curve), and carotid artery elasticity were evaluated across pubertal stages (Tanner I vs Tanner II-IV vs Tanner V) in 344 children and adolescents (184 males, 160 females; ages 6 to 21 years). One hundred twenty-four subjects (mean age 8.23 ± 0.15 years; 52 females) were Tanner stage I; 105 subjects (mean age 13.19 ± 0.17 years; 47 females) were Tanner stages II-IV; and 115 subjects (mean age 17.19 ± 0.16 years; 61 females) were Tanner stage V. There were no significant differences for any of the measures of vascular structure and function across pubertal stages. Results of the current study indicate that smooth-muscle and endothelial function, as well as carotid artery elasticity, do not differ throughout pubertal development and that accounting for pubertal stage when reporting vascular data in children and adolescents may be unnecessary. Copyright © 2013 Mosby, Inc. All rights reserved.

  10. Assymetry of temporal artery diameters during spontaneous attacks of cluster headache

    DEFF Research Database (Denmark)

    Nielsen, Thue H; Tfelt-Hansen, Peer; Iversen, Helle K

    2009-01-01

    BACKGROUND: Cluster headache is characterized by strictly unilateral head pain associated with symptoms of cranial autonomic features. Transcranial Doppler studies showed in most studies a bilateral decreased blood flow velocity in the middle cerebral artery. OBJECTIVE: To investigate whether...... there is a bilateral or unilateral extracranial vasodilation during spontaneous cluster headache attacks. DESIGN AND METHODS: In 9 cluster headache patients, we investigated the luminal diameter of the superficial temporal artery with ultrasound on the headache and headache-free side during and outside cluster...... headache attacks. RESULTS: During cluster headache attacks, the diameter of the superficial temporal artery on the painful side was greater, 1.48 mm, than the diameter on the nonheadache site, 1.14 mm (P

  11. On Elasticity Measurement in Cloud Computing

    Directory of Open Access Journals (Sweden)

    Wei Ai

    2016-01-01

    Full Text Available Elasticity is the foundation of cloud performance and can be considered as a great advantage and a key benefit of cloud computing. However, there is no clear, concise, and formal definition of elasticity measurement, and thus no effective approach to elasticity quantification has been developed so far. Existing work on elasticity lack of solid and technical way of defining elasticity measurement and definitions of elasticity metrics have not been accurate enough to capture the essence of elasticity measurement. In this paper, we present a new definition of elasticity measurement and propose a quantifying and measuring method using a continuous-time Markov chain (CTMC model, which is easy to use for precise calculation of elasticity value of a cloud computing platform. Our numerical results demonstrate the basic parameters affecting elasticity as measured by the proposed measurement approach. Furthermore, our simulation and experimental results validate that the proposed measurement approach is not only correct but also robust and is effective in computing and comparing the elasticity of cloud platforms. Our research in this paper makes significant contribution to quantitative measurement of elasticity in cloud computing.

  12. Some Measurements of Elasticities of Substitution

    NARCIS (Netherlands)

    J. Tinbergen (Jan)

    1946-01-01

    textabstractSo far, when measuring elasticities of demand, most econometricians have concentrated upon the plain elasticity of total demand for a given commodity. For many important problems we should, in addition, like to know something of "partial elasticities," as I might provisionally call them.

  13. Complementary energy principle for large elastic deformation

    Institute of Scientific and Technical Information of China (English)

    GAO; Yuchen

    2006-01-01

    Using the "base forces" as the fundamental unknowns to determine the state of an elastic system, the complementary energy principle for large elastic deformation is constructed for the conjugate quantities being displacement gradients, which possesses exactly the same form as that of classical linear elasticity. It is revealed that the complementary energy contains deformation part and rotation part.

  14. SOME OBSERVATIONS OF TWO INTERFERING VIV CIRCULAR CYLINDERS OF UNEQUAL DIAMETERS IN TANDEM

    Institute of Scientific and Technical Information of China (English)

    HUANG Shan; SWORN Andy

    2011-01-01

    Analysis of model test results was carried out to investigate the hydrodynamic interaction between a pair of elastically-supported rigid cylinders of dissimilar diameters in a water flume.The two cylinders are placed in tandem with one situated in the wake of the other.The diameter of the upstream cylinder is twice as large as that of the downstream cylinder.The spacing between the two cylinders ranges from 1 to 10 times the larger cylinder diameter.The Reynolds numbers are within the sub-critical range.The cylinders are free to oscillate in both the in-line and the cross-flow directions.The reduced velocity ranges from 1 to 10 and the low damping ratio of the model test set-up at 0.006 gives a combined m.ass-damping parameter of 0.02.It is found that the lift on and the cross-flow motion of the downstream cylinder have the frequency components derived from the upstream cylinder's vortex shedding as well as from its own vortex shedding,and the relative importance of the two sources of excitation is influenced by the spacing between the two cylinders.The downstream cylinder's VIV response appears to be largely dependent upon the actual reduced velocity of the cylinder.

  15. Ageing effects on the diameter, nanomechanical properties and tactile perception of human hair.

    Science.gov (United States)

    Tang, W; Zhang, S G; Zhang, J K; Chen, S; Zhu, H; Ge, S R

    2016-04-01

    The typical changes to hair associated with ageing are greying, thinning, dryness and brittleness. Research on the influence of ageing on hair properties will enable a detailed understanding of the natural ageing process. The studies were carried out using an SEM (scanning electron microscope), a TriboIndenter and an artificial finger. Three characteristic features of tactile perception that could reflect the perceptual dimensions of the fineness, roughness and slipperiness of hair were extracted. The influences of ageing on the diameter, surface topography, nanomechanical properties and tactile perception of hair were determined. In the three age group hair samples, the children's group hair samples have the smallest diameter. The hair cuticles in the children and young adult groups were relatively complete and less damaged than in the elderly group. The hardness and elastic modulus of the young adult group's hair samples were higher than those in the elderly and children's groups. For all groups, loss modulus E" was smaller than storage modulus E'. Vertical deviations (R) and coefficient of friction (μ) increased, and spectral centroid (SC) decreased, with the increase in age. Ageing decreased the tactile perception of hair. Ageing influences the diameter, surface topography, hardness, loss modulus, storage modulus and tactile perception of human hair. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  16. Blood transfusions

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000431.htm Blood transfusions To use the sharing features on this ... several sources of blood which are described below. Blood From the Public (Volunteer Blood Donation) The most ...

  17. Blood smear

    Science.gov (United States)

    ... some red blood cells shaped like spheres ( hereditary spherocytosis ) Increased breakdown of RBCs Presence of RBCs with ... normal Red blood cells, elliptocytosis Red blood cells, spherocytosis Acute lymphocytic leukemia - photomicrograph Red blood cells, multiple ...

  18. Blood culture

    Science.gov (United States)

    Culture - blood ... A blood sample is needed . The site where blood will be drawn is first cleaned with an antiseptic such ... organism from the skin getting into (contaminating) the blood sample and causing a false-positive result (see ...

  19. Blood Thinners

    Science.gov (United States)

    If you have some kinds of heart or blood vessel disease, or if you have poor blood flow to your brain, your doctor may recommend that you take a blood thinner. Blood thinners reduce the risk of heart ...

  20. Blood typing

    Science.gov (United States)

    A blood sample is needed. The test to determine your blood group is called ABO typing. Your blood sample is mixed with antibodies against type A and B blood. Then, the sample is checked to see whether ...

  1. Effects of Magnetic Field, Porosity and Wall Properties for Anisotropically Elastic Multi-Stenosis Arteries on the Characteristics of Blood Flow%磁场、多孔性和各向异性动脉壁有多处狭窄段时对血液流动的影响

    Institute of Scientific and Technical Information of China (English)

    Kh·S·梅克赫默; M·H·哈劳恩; M·A·艾可特

    2011-01-01

    A mathematical model for blood flow through an elastic artery with multi-stenosis under effect of a magnetic field in a porous medium was presented. The arterial segment under consideration was simulated by an anisotropically elastic cylindrical tube filled with a viscous incompressible electrically conducting fluid representing blood. The analysis was carried out for an artery with mild local narrowing in its lumen forming a stenosis. The effects of arterial wall parameters that represent the viscoelastic stresses components acting along the longitudinal and circumferential directions T, and T, respectively, the degree of anisotropy of the vessel wall y, the total mass of the vessel and the surrounding tissues M and the contributions of the viscous and elastic constraints to the total tethering C and K respectively on the resistance impedance, the wall shear stress distribution, the radial and axial velocities had been well illustrated. Also the effects of the stenosis shape m, the constant of permeability k, the Hartmann number Ha and the maximum height of the stenosis size S on the fluid flow characteristics were investigated. The obtained results show that the flow was appreciably influenced by the surrounding connective tissues of the motion of the arterial wall and the degree of anisotropy of the vessel wall play an important role to determine the material of the artery. Further the wall shear stress distribution increases with increasing Tt and y while it decreases with increasing T,, M, C and K. The transmission of the wall shear stress distribution and the resistance impedance at the wall surface through a tethered tube were substantially lower than those through the free tube while the shearing stress distribution at the stenosis throat had inverse character through totally tethered and tree tubes. The trapping bolus increases in size toward the line center of the tube as the constant of permeability k increases and it decreases by increasing Hartmann

  2. Continuous retinal vessel diameter measurements: the future in retinal vessel assessment?

    Science.gov (United States)

    Heitmar, Rebekka; Blann, Andrew D; Cubbidge, Robert P; Lip, Gregory Y H; Gherghel, Doina

    2010-11-01

    To establish an alternative method, sequential and diameter response analysis (SDRA), to determine dynamic retinal vessel responses and their time course in serial stimulation compared with the established method of averaged diameter responses and standard static assessment. SDRA focuses on individual time and diameter responses, taking into account the fluctuation in baseline diameter, providing improved insight into reaction patterns when compared with established methods as delivered by retinal vessel analyzer (RVA) software. SDRA patterns were developed with measurements from 78 healthy nonsmokers and subsequently validated in a group of 21 otherwise healthy smokers. Fundus photography and retinal vessel responses were assessed by RVA, intraocular pressure by contact tonometry, and blood pressure by sphygmomanometry. Compared with the RVA software method, SDRA demonstrated a marked difference in retinal vessel responses to flickering light (P SDRA showed a strong relation between baseline retinal vessel diameter and subsequent dilatory response in both healthy subjects and smokers (P = 0.001). The RVA software was unable to detect this difference or to find a difference in retinal vessel arteriovenous ratio between smokers and nonsmokers (P = 0.243). However, SDRA revealed that smokers' vessels showed both an increased level of arterial baseline diameter fluctuation before flicker stimulation (P = 0.005) and an increased stiffness of retinal arterioles (P = 0.035) compared with those in nonsmokers. These differences were unrelated to intraocular pressure or systemic blood pressure. SDRA shows promise as a tool for the assessment of vessel physiology. Further studies are needed to explore its application in patients with vascular diseases.

  3. The k-Diameter of a Kind of Circulant Graph

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xian-di

    2004-01-01

    The diameter of a graph G is the maximal distance between pairs of vertices of G. When a network is modeled as a graph,diameter is a measurement for maximum transmission delay. The k-diameter dk(G) of a graph G, which deals with k internally disjoint paths between pairs of vertices of G, is a extension of the diameter of G. It has widely studied in graph theory and computer science. The circulant graph is a group-theoretic model of a class of symmetric interconnection network. Let Cn(i, ) be a circulant graph of order n whose spanning elements are i and , where n≥4 and n is even. In this paper, the diameter, 2-diameter and 3-diameter of the Cn(i,) are all obtained if gcd(n,i)=1, where the symbol gcd(n,i) denotes the maximum common divisor of n and i.

  4. Tool Geometry for Friction Stir Welding—Optimum Shoulder Diameter

    Science.gov (United States)

    Mehta, M.; Arora, A.; de, A.; Debroy, T.

    2011-09-01

    The most important geometric parameter in the friction stir welding (FSW) tool design is the shoulder diameter, which is currently estimated by trial and error. Here, we report a combined experimental and theoretical investigation on the influence of shoulder diameter on thermal cycles, peak temperatures, power requirements, and torque during FSW of AA7075-T6. An optimum tool shoulder diameter is identified using a three-dimensional, heat transfer and materials flow model. First, the predictive capability of the model is tested by comparing the computed values of peak temperature, spindle power, and torque requirements for various shoulder diameters against the corresponding experimental data. The change in the values of these variables with shoulder diameter is correctly predicted by the model. The model is then used to identify the optimum tool shoulder diameter that facilitates maximal use of the supplied torque in overcoming interfacial sticking. The tool with optimum shoulder diameter is shown to result in acceptable yield strength (YS) and ductility.

  5. Radial elasticity of multi-walled boron nitride nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Michael W. Smith, Cheol Park, Meng Zheng, Changhong Ke ,In-Tae Bae, Kevin Jordan

    2012-02-01

    We investigated the radial mechanical properties of multi-walled boron nitride nanotubes (MW-BNNTs) using atomic force microscopy. The employed MW-BNNTs were synthesized using pressurized vapor/condenser (PVC) methods and were dispersed in aqueous solution using ultrasonication methods with the aid of ionic surfactants. Our nanomechanical measurements reveal the elastic deformational behaviors of individual BNNTs with two to four tube walls in their transverse directions. Their effective radial elastic moduli were obtained through interpreting their measured radial deformation profiles using Hertzian contact mechanics models. Our results capture the dependences of the effective radial moduli of MW-BNNTs on both the tube outer diameter and the number of tube layers. The effective radial moduli of double-walled BNNTs are found to be several-fold higher than those of single-walled BNNTs within the same diameter range. Our work contributes directly to a complete understanding of the fundamental structural and mechanical properties of BNNTs and the pursuits of their novel structural and electronics applications.

  6. Size effects in the elastic deformation behavior of metallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Patrick; Peukert, Wolfgang, E-mail: W.Peukert@lfg.uni-erlangen.de [Friedrich-Alexander-University Erlangen-Nuremberg, Institute for Particle Technology (Germany)

    2012-12-15

    In this work, the results of a series of molecular statics simulations to investigate the size dependence of the elastic properties of metallic nanoparticles are presented. The per-atom stiffness tensor was calculated from the derivative of the used embedded atom method potentials and, from it, lower order elastic parameters, such as the Young's modulus or the Poisson ratio. The Young's modulus decayed up to 30 % relative to the bulk values for 2.5 nm small particles, whereas the Poisson ratio showed an increase with decreasing particle size for most materials. Particles with a diameter of 30 nm approached the continuum values to around 1 %, marking the transition to continuum theory. The size-dependent Young's modulus and several other material properties can be described by a simple algebraic function of the number of atoms per particle. By plotting the radial distribution of the local Young's modulus within particles of different size, it is shown that only the outermost 2-3 atomic layers are responsible for the size-dependent change of elastic properties. Within these layers, the average atomic stiffness was found to decay linearly and independent of the particle size.

  7. Determination of the luminal diameter of the radial artery in man by high frequency ultrasound

    DEFF Research Database (Denmark)

    Nielsen, T H; Iversen, Helle Klingenberg; Tfelt-Hansen, P

    1990-01-01

    measurements. By comparing the diameter of the reference object either filled with water or blood at 37 degrees C, the ultrasound velocity in human blood at 37 degrees C was calculated to be 1605 m/s. The intraobserver repeatability coefficients of in-vivo measurements of the radial artery in man were...... in the same range, whether measurements were repeated after 30 min (14%) or from day to day (12%). The interobserver repeatability coefficient was acceptable (15%) when the site of measurements was marked, whereas measurements without a mark resulted in a repeatability coefficient of 24%. The intravenous...

  8. Characteristics of Angora rabbit fiber using optical fiber diameter analyzer.

    Science.gov (United States)

    Rafat, S A; de Rochambeau, H; Brims, M; Thébault, R G; Deretz, S; Bonnet, M; Allain, D

    2007-11-01

    An experiment was conducted to describe the characteristics of Angora rabbit fiber using optical fiber diameter analyzer (OFDA). A total of 349 fleece samples were collected from 60 French Angora rabbits. Recorded measurements of OFDA were as follows: mean fiber diameter, CV of fiber diameter, comfort factor, spinning fineness, mean fiber curvature, SD of fiber curvature, mean opacity of fibers, percentage of medullated fibers, mean fiber diameter along the length, and SD of fiber diameter along the length. Comfort factor is the percentage of fibers less than or equal to 30 microns. The main effects included in the mixed model were fixed effects of group, harvest season, and age and a random effect of animal. Correlations among total fleece weight, compression, and OFDA measurements were calculated. Mean fiber diameter was lower than the fiber diameter along the length. Mean percentage of medullated fibers was very low and ranged from 0.1 to 7.3%. The mean comfort factor was 97.5% and ranged from 93.3 to 99.8%. The mean fiber curvature was 40.1 degrees/mm. The major changes in Angora fleece characteristics from 8 to 105 wk of age were an increase in fiber diameter, CV of fiber diameter, mean fiber diameter along the length and curvature, and a decrease in compression and comfort factor. The effect of harvest season was significant on some fiber characteristics. Mean fiber diameter and the mean fiber diameter along the length had a positive correlation with total fleece weight. The OFDA methodology is a method to evaluate fiber diameter, CV of fiber diameter, and bristle content through measuring of the comfort factor. However, OFDA is not adapted for measuring opacity or size of the medulla, or both, in Angora wool and needs a new definition or a special calibration. The spinning fineness should be redefined and adapted for Angora rabbits.

  9. Estimation of genetic parameters for wool fiber diameter measures.

    Science.gov (United States)

    Iman, N Y; Johnson, C L; Russell, W C; Stobart, R H

    1992-04-01

    Genetic and phenotypic correlations and heritability estimates of side, britch, and core diameters; side and britch CV; side and britch diameter difference; and clean fleece weight were investigated using 385 western white-faced ewes produced by 50 sires and maintained at two locations on a selection study. Data were analyzed using analysis of variance procedures, and effects in the final model included breed of sire-selection line combination, sire within breed-selection line, and location. Heritabilities were estimated by paternal half-sib analysis. Sires within breed-selection line represented a significant source of variation for all traits studied. Location had a significant effect on side diameter, side and britch diameter difference, and clean fleece weight. Age of ewe only affected clean fleece weight. Phenotypic and genetic correlations among side, britch, and core diameter measures were high and positive. Phenotypic correlations ranged from .68 to .75 and genetic correlations ranged from .74 to .89. The genetic correlations between side and britch diameter difference and side diameter or core diameter were small (-.16 and .28, respectively). However, there was a stronger genetic correlation between side and britch diameter difference and britch diameter (.55). Heritability of the difference between side and britch diameter was high (.46 +/- .16) and similar to heritability estimates reported for other wool traits. Results of this study indicate that relatively rapid genetic progress through selection for fiber diameter should be possible. In addition, increased uniformity in fiber diameter should be possible through selection for either side and britch diameter difference or side or britch CV.

  10. Electrodynamic forces in elastic matter

    CERN Document Server

    Antoci, S

    2000-01-01

    A macroscopic theory for the dynamics of elastic, isotropic matter in presence of electromagnetic fields is proposed here. We avail of Gordon's general relativistic derivation of Abraham's electromagnetic energy tensor as starting point. The necessary description of the elastic and of the inertial behaviour of matter is provided through a four dimensional generalisation of Hooke's law, made possible by the introduction of a four dimensional ``displacement'' vector. As intimated by Nordstroem, the physical origin of electrostriction and of magnetostriction is attributed to the change in the constitutive equation of electromagnetism caused by the deformation of matter. The part of the electromagnetic Lagrangian that depends on that deformation is given explicitly for the case of an isotropic medium and the resulting expression of the electrostrictive force is derived, thus showing how more realistic equations of motion for matter subjected to electromagnetic fields can be constructed.

  11. Elastic deformations of compact stars

    CERN Document Server

    Andersson, Lars; Schmidt, Bernd G

    2014-01-01

    We prove existence of solutions for an elastic body interacting with itself through its Newtonian gravitational field. Our construction works for configurations near one given by a self-gravitating ball of perfect fluid. We use an implicit function argument. In so doing we have to revisit some classical work in the astrophysical literature concerning linear stability of perfect fluid stars. The results presented here extend previous work by the authors, which was restricted to the astrophysically insignificant situation of configurations near one of vanishing stress. In particular, "mountains on neutron stars", which are made possible by the presence of an elastic crust in neutron stars, can be treated using the techniques developed here.

  12. Elastic modulus of viral nanotubes

    Science.gov (United States)

    Zhao, Yue; Ge, Zhibin; Fang, Jiyu

    2008-09-01

    We report an experimental and theoretical study of the radial elasticity of tobacco mosaic virus (TMV) nanotubes. An atomic force microscope tip is used to apply small radial indentations to deform TMV nanotubes. The initial elastic response of TMV nanotubes can be described by finite-element analysis in 5nm indentation depths and Hertz theory in 1.5nm indentation depths. The derived radial Young’s modulus of TMV nanotubes is 0.92±0.15GPa from finite-element analysis and 1.0±0.2GPa from the Hertz model, which are comparable with the reported axial Young’s modulus of 1.1GPa [Falvo , Biophys. J. 72, 1396 (1997)].

  13. Elastic cone for Chinese calligraphy

    Science.gov (United States)

    Cai, Fenglei; Li, Haisheng

    2014-01-01

    The brush plays an important role in creating Chinese calligraphy. We regard a single bristle of a writing brush as an elastic rod and the brush tuft absorbing ink as an elastic cone, which naturally deforms according to the force exerted on it when painting on a paper, and the brush footprint is formed by the intersection region between the deformed tuft and the paper plane. To efficiently generate brush strokes, this paper introduces interpolation and texture mapping approach between two adjacent footprints, and automatically applies bristle-splitting texture to the stroke after long-time painting. Experimental results demonstrate that our method is effective and reliable. Users can create realistic calligraphy in real time.

  14. Elastic scattering in geometrical model

    Science.gov (United States)

    Plebaniak, Zbigniew; Wibig, Tadeusz

    2016-10-01

    The experimental data on proton-proton elastic and inelastic scattering emerging from the measurements at the Large Hadron Collider, calls for an efficient model to fit the data. We have examined the optical, geometrical picture and we have found the simplest, linear dependence of this model parameters on the logarithm of the interaction energy with the significant change of the respective slopes at one point corresponding to the energy of about 300 GeV. The logarithmic dependence observed at high energies allows one to extrapolate the proton-proton elastic, total (and inelastic) cross sections to ultra high energies seen in cosmic rays events which makes a solid justification of the extrapolation to very high energy domain of cosmic rays and could help us to interpret the data from an astrophysical and a high energy physics point of view.

  15. Variants of lumbosacral elastic band.

    Directory of Open Access Journals (Sweden)

    Carlos Cesar Santín Alfaro

    2011-06-01

    Full Text Available It is made an intervention research, qualitative and quantitative of two variants of lumbosacral elastic bands used in Provincial Laboratory of Technical Orthopedics in Sancti Spiritus Province, taking into account the high demand for this device and that the laboratory do not often count with the raw material needed for the original lumbosacral belt made by denim cloth which is the conventional belt. The main goal of this research is to explain the technological process and to compare the cost of production of both elastic variants with lumbosacral belt made by cloth which are offer to patients who look for this service , giving them a rapid solution so that they can feel comfortable.

  16. Elasticity of Long Distance Travelling

    DEFF Research Database (Denmark)

    Knudsen, Mette Aagaard

    2011-01-01

    With data from the Danish expenditure survey for 12 years 1996 through 2007, this study analyses household expenditures for long distance travelling. Household expenditures are examined at two levels of aggregation having the general expenditures on transportation and leisure relative to five other...... aggregated commodities at the highest level, and the specific expenditures on plane tickets and travel packages at the lowest level. The Almost Ideal Demand System is applied to determine the relationship between expenditures on transportation and leisure and all other purchased non-durables within...... packages has higher income elasticity of demand than plane tickets but also higher than transportation and leisure in general. The findings within price sensitiveness are not as sufficient estimated, but the model results indicate that travel packages is far more price elastic than plane tickets which...

  17. Investigation of the dynamic diameter deformation of vascular stents during fatigue testing with radial loading

    Directory of Open Access Journals (Sweden)

    Boeck Maria

    2015-09-01

    Full Text Available Endovascular stents are exposed to cyclic loads resulting from daily activity and pulsatile arterial blood pressure. DIN EN ISO 25539-2 and FDA guideline 1545 recommend durability testing, exposing stents to physiological cyclic loads for a 10 year equivalent. For accelerated testing, the simulated deformation has to be comparable to physiological in-vivo deformation. A new test setup is presented to determine diameter deformation of vascular stents during fatigue testing with radial loading.

  18. Elastic Curves on the Sphere

    Science.gov (United States)

    1992-12-16

    12 = (K,, + )- (29) K 2 (see [3]). The parameter KM represents the amplitude of the periodic curva - ture function and sm denotes the value at which K...Additamentum De curvis elasticis. Methodus Inveniendi Lineas Curvas Maximi Minimive Proprietate Gaudentes, Ser. 1., Vol. 24, Lausanne 1744. 17 [10...Mathematical Theory of Elasticity. 4th. ed., Cambridge University Press, 1927. [12] G. Nielson. Bernstein/ Bezier Curves and Splines on Spheres based upon

  19. Teaching nonlinear dynamics through elastic cords

    Energy Technology Data Exchange (ETDEWEB)

    Chacon, R; Galan, C A; Sanchez-Bajo, F, E-mail: rchacon@unex.e [Departamento de Fisica Aplicada, Escuela de IngenierIas Industriales, Universidad de Extremadura, Apartado Postal 382, E-06071 Badajoz (Spain)

    2011-01-15

    We experimentally studied the restoring force of a length of stretched elastic cord. A simple analytical expression for the restoring force was found to fit all the experimental results for different elastic materials. Remarkably, this analytical expression depends upon an elastic-cord characteristic parameter which exhibits two limiting values corresponding to two nonlinear springs with different Hooke's elastic constants. Additionally, the simplest model of elastic cord dynamics is capable of exhibiting a great diversity of nonlinear phenomena, including bifurcations and chaos, thus providing a suitable alternative model system for discussing the basic essentials of nonlinear dynamics in the context of intermediate physics courses at university level.

  20. Transient waves in visco-elastic media

    CERN Document Server

    Ricker, Norman

    1977-01-01

    Developments in Solid Earth Geophysics 10: Transient Waves in Visco-Elastic Media deals with the propagation of transient elastic disturbances in visco-elastic media. More specifically, it explores the visco-elastic behavior of a medium, whether gaseous, liquid, or solid, for very-small-amplitude disturbances. This volume provides a historical overview of the theory of the propagation of elastic waves in solid bodies, along with seismic prospecting and the nature of seismograms. It also discusses the seismic experiments, the behavior of waves propagated in accordance with the Stokes wave

  1. Phase diagram of elastic spheres.

    Science.gov (United States)

    Athanasopoulou, L; Ziherl, P

    2017-02-15

    Experiments show that polymeric nanoparticles often self-assemble into several non-close-packed lattices in addition to the face-centered cubic lattice. Here, we explore theoretically the possibility that the observed phase sequences may be associated with the softness of the particles, which are modeled as elastic spheres interacting upon contact. The spheres are described by two finite-deformation theories of elasticity, the modified Saint-Venant-Kirchhoff model and the neo-Hookean model. We determine the range of indentations where the repulsion between the spheres is pairwise additive and agrees with the Hertz theory. By computing the elastic energies of nine trial crystal lattices at densities far beyond the Hertzian range, we construct the phase diagram and find the face- and body-centered cubic lattices as well as the A15 lattice and the simple hexagonal lattice, with the last two being stable at large densities where the spheres are completely faceted. These results are qualitatively consistent with observations, suggesting that deformability may indeed be viewed as a generic property that determines the phase behavior in nanocolloidal suspensions.

  2. Nano-hardness and elastic modulus of anodic aluminium oxide based Poly (2-hydroxyethylmethacrylate composite membranes

    Directory of Open Access Journals (Sweden)

    Gérrard Eddy Jai Poinern

    2014-07-01

    Full Text Available In this study we determine the elastic and hardness properties of electrochemically engineered porous anodic aluminium oxide (AAO membranes and AAO membranes infiltrated with Poly (2-hydroxyethylmethacrylate to form a unique biologically compatible AAO/polymer composite. The electrochemically-synthesised membranes have a nanometre scale porous oxide structure with a mean pore diameter of 100 nm. The membranes were characterized using field emission scanning electron microscopy before and after polymer infiltration. The polymer treated and untreated membranes were then examined using the nano-indentation technique to measure the hardness and subsequently determine the membrane elasticity.

  3. To assess the intimal thickness, flow velocities, and luminal diameter of carotid arteries using high-resolution B-mode ultrasound doppler imaging

    Science.gov (United States)

    Vemuru, Madhuri; Jabbar, Afzal; Chandra, Suman

    2004-04-01

    Carotid imaging is a Gold Standard test that provides useful information about the structure and functions of carotid arteries. Spectral imaging helps to evaluate the vessel and hemodynamic changes. High resolution B-mode imaging has emerged as one of the methods of choice for determining the anatomic extent of atherosclerosis and its progression and for assessing cardiovascular risks. The measurements made with Doppler correlate well with pathologic measurements. Recent prospective studies have clearly demonstrated that these measurements of carotid intimal thickness are potent predictors of Myocardial Infarction and Stroke. This method appears very attractive as it is non-invasive, extremely safe, well accepted by the patient and relatively inexpensive. It can be performed serially and has the advantage of visualizing the arterial wall in contrast to angiographic techniques which provide only an outline of the arterial lumen. Recently, there has been an interest in the clinical use of this technique in making difficult clinical decisions like deciding on preventive therapies. 30 subjects aged 21-60 years and 30 subjects aged 61-85 years of both sexes are selected after doing a baseline study to exclude Hypertension, Diabetes, Obesity and Hyperlipidemia. The carotid arteries were examined for intimal thickening, blood flow velocities and luminal diameter. With aging there is a narrowing of the carotid vessels and significant increase in intimal thickening with a consequent increase in the blood flow velocities. Inter-observer, intra-observer and instrument variations are seen and there is no significant change in the values when the distal flow pattern is considered for measurements. Aging produces major cardiovascular changes including decreased elasticity and compliance of great arteries leading to structural and functional alterations in heart and vessels. With aging there is increased intimal thickness and increased pulse wave velocity which is clearly

  4. VEGF165 Stimulates Vessel Density and Vessel Diameter Differently in Angiogenesis and Lymphangiogenesis

    Science.gov (United States)

    Parsons-Wingerter, Patricia; Radhakrishnan, Krishnan; DiCorleto, Paul E.; Leontiev, Dmitry; Anand-Apte, Bela; Albarran, Brian; Farr, Andrew G.

    2005-01-01

    Vascular endothelial growth factor-165 (VEGF(sub 165)) stimulated angiogenesis in the quail chorioallantoic membrane (CAM) by vessel expansion from the capillary network. However, lymphangiogenesis was stimulated by the filopodial guidance of tip cells located on blind-ended lymphatic sprouts. As quantified by fractal/generational branching analysis using the computer code VESGEN, vascular density increased maximally at low VEGF concentrations, and vascular diameter increased most at high VEGF concentrations. Increased vascular density and diameter were statistically independent events (r(sub s), -0.06). By fluorescence immunohistochemistry of VEGF receptors VEGFR-1 and VEGFR-2, alpha smooth muscle actin ((alpha) SMA) and a vascular/lymphatic marker, VEGF(sub 165) increased the density and diameter of sprouting lymphatic vessels guided by tip cells (accompanied by the dissociation of lymphatics from blood vessels). Isolated migratory cells expressing (alpha)SMA were recruited to blood vessels, whereas isolated cells expressing VEGFR-2 were recruited primarily to lymphatics. In conclusion, VEGF(sub 165) increased lymphatic vessel density by lymphatic sprouting, but increased blood vessel density by vascular expansion from the capillary network.

  5. Analysis of Gear Wheel-shaft Joint Characterized by Comparable Pitch Diameter and Mounting Diameter

    Directory of Open Access Journals (Sweden)

    J. Ryś

    2003-01-01

    Full Text Available This paper presents the design procedure for a gear wheel-shaft direct frictional joint. The small difference between the operating pitch diameter of the gear and the mounting diameter of the frictional joint is the key feature of the connection. The contact surface of the frictional joint must be placed outside the bottom land of the gear, and the geometry of the joint is limited to the specific type of solutions.The strength analysis is based on the relation between the torque and statistical load intensity of the gear transmission. Several dimensionless parameters are introduced to simplify the calculations. Stress-strain verifying analysis with respect to combined loading, the condition of appropriate load-carrying capacity of the frictional joint and the fatigue strength of the shaft are applied to obtain the relations between the dimensions of the joint and other parameters. The final engineering solution may then be suggested. The approach is illustrated by a numerical example.The proposed procedure can be useful in design projects for small, high-powered modern reducers and new-generation geared motors, in particular when manufactured in various series of types.

  6. Elastic fibres in health and disease.

    Science.gov (United States)

    Baldwin, Andrew K; Simpson, Andreja; Steer, Ruth; Cain, Stuart A; Kielty, Cay M

    2013-08-20

    Elastic fibres are insoluble components of the extracellular matrix of dynamic connective tissues such as skin, arteries, lungs and ligaments. They are laid down during development, and comprise a cross-linked elastin core within a template of fibrillin-based microfibrils. Their function is to endow tissues with the property of elastic recoil, and they also regulate the bioavailability of transforming growth factor β. Severe heritable elastic fibre diseases are caused by mutations in elastic fibre components; for example, mutations in elastin cause supravalvular aortic stenosis and autosomal dominant cutis laxa, mutations in fibrillin-1 cause Marfan syndrome and Weill-Marchesani syndrome, and mutations in fibulins-4 and -5 cause autosomal recessive cutis laxa. Acquired elastic fibre defects include dermal elastosis, whereas inflammatory damage to fibres contributes to pathologies such as pulmonary emphysema and vascular disease. This review outlines the latest understanding of the composition and assembly of elastic fibres, and describes elastic fibre diseases and current therapeutic approaches.

  7. Instability and "Sausage-String" Appearance in Blood Vessels during High Blood Pressure

    CERN Document Server

    Alstrøm, P; Colding-Jorgensen, M; Gustafsson, F; Holstein-Rathlou, N H; Alstrom, Preben; Eguiluz, Victor M.; Colding-Jorgensen, Morten; Gustafsson, Finn; Holstein-Rathlou, Niels-Henrik

    1999-01-01

    A new Rayleigh-type instability is proposed to explain the `sausage-string' pattern of alternating constrictions and dilatations formed in blood vessels under influence of a vasoconstricting agent. Our theory involves the nonlinear elasticity characteristics of the vessel wall, and provides predictions for the conditions under which the cylindrical form of a blood vessel becomes unstable.

  8. Motivation and compliance with intraoral elastics.

    Science.gov (United States)

    Veeroo, Helen J; Cunningham, Susan J; Newton, Jonathon Timothy; Travess, Helen C

    2014-07-01

    Intraoral elastics are commonly used in orthodontics and require regular changing to be effective. Unfortunately, poor compliance with elastics is often encountered, especially in adolescents. Intention for an action and its implementation can be improved using "if-then" plans that spell out when, where, and how a set goal, such as elastic wear, can be put into action. Our aim was to determine the effect of if-then plans on compliance with elastics. To identify common barriers to compliance with recommendations concerning elastic wear, semistructured interviews were carried out with 14 adolescent orthodontic patients wearing intraoral elastics full time. Emerging themes were used to develop if-then plans to improve compliance with elastic wear. A prospective pilot study assessed the effectiveness of if-then planning aimed at overcoming the identified barriers on compliance with elastic wear. Twelve participants were randomized equally into study and control groups; the study group received information about if-then planning. The participants were asked to collect used elastics, and counts of these were used to assess compliance. A wide range of motivational and volitional factors were described by the interviewed participants, including the perceived benefits of elastics, cues to remember, pain, eating, social situations, sports, loss of elastics, and breakages. Compliance with elastic wear was highly variable among patients. The study group returned more used elastics, suggesting increased compliance, but the difference was not significant. The use of if-then plans might improve compliance with elastic wear when compared with routine clinical instructions. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  9. Impaired endothelial progenitor cell activity is associated with reduced arterial elasticity in patients with essential hypertension.

    Science.gov (United States)

    Yang, Zhen; Chen, Long; Su, Chen; Xia, Wen-Hao; Wang, Yan; Wang, Jie-Mei; Chen, Fei; Zhang, Yuan-Yuan; Wu, Fang; Xu, Shi-Yue; Zhang, Xiao-Lin; Tao, Jun

    2010-01-01

    Endothelial dysfunction is related to reduced arterial elasticity in patients with essential hypertension. Circulating endothelial progenitor cells (EPCs), an important endogenous repair approach for endothelial injury, is altered in hypertensive patients. However, the association between alteration in circulating EPCs and hypertension-related reduced arterial elasticity has not been reported. The purpose of this study is to investigate the association between alteration in circulating EPCs and hypertension-related reduced arterial elasticity. We measured the artery elasticity profiles including brachial-ankle PWV (baPWV) and C1 large and C2 small artery elasticity indices in patients with essential hypertension (n = 20) and age-matched normotensive subjects (n = 21). The number and activity of circulating EPCs isolated from peripheral blood were determined. Compared to normotensive subjects, the patients with hypertension exhibited decreased C1 large and C2 small artery elasticity indices, as well as increased baPWV. The number of circulating EPCs did not differ between the two groups. The migratory and proliferative activities of circulating EPCs in hypertensive patients were lower than those in normotensive subjects. Both proliferatory and migratory activities of circulating EPCs closely correlated with arterial elasticity profiles, including baPWV and C1 large and C2 small artery elasticity indices. Multivariate analysis identified both proliferative and migratory activities of circulating EPCs as independent predictors of the artery elasticity profiles. The present study demonstrates for the first time that impaired activity of circulating EPCs is associated with reduced arterial elasticity in patients with hypertension. The fall in endogenous repair capacity of vascular endothelium may be involved in the pathogenesis of hypertension-related vascular injury.

  10. Effect of Adsorbent Diameter on the Performance of Adsorption Refrigeration

    Institute of Scientific and Technical Information of China (English)

    黄宏宇; 何兆红; 袁浩然; 小林敬幸; 赵丹丹; 窪田光宏; 郭华芳

    2014-01-01

    Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can af-fect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was investigated. The heat transfer coefficient of the refrigerant and the void rate of the adsorbent layer can also affect the effective thermal conductivity of adsorbents. The performance of mass transfer in the adsorber is better when pressure drop decreases. Pressure drop decreases with increasing permeability. The permeability of the adsorbent layer can be improved with increasing adsorbent diameter. The effect of adsorbent diameter on refrigeration output power was experimentally studied. Output power initially increases and then decreases with increasing diameter under different cycle time conditions. Output power increases with decreasing cycle time under similar diameters.

  11. On super edge-graceful trees of diameter four

    CERN Document Server

    Krop, E; Raridan, C

    2011-01-01

    In "On the super edge graceful trees of even orders," Chung, Lee, Gao, and Schaffer posed the following problem: Characterize trees of diameter 4 which are super edge-graceful. In this paper, we provide super edge-graceful labelings for all caterpillars and even size lobsters of diameter 4 which permit such labelings. We also provide super edge-graceful labelings for several families of odd size lobsters of diameter 4.

  12. k-Diameter of Circulant Graph with Degree 3

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xian-di; LI Man-li

    2005-01-01

    Parameters k-distance and k-diameter are extension of the distance and the diameter in graph theory. In this paper, the k-distance dk (x,y) between the any vertices x andy is first obtained in a connected circulant graph G with order n (n is even) and degree 3 by removing some vertices from the neighbour set of the x. Then, the k-diameters of the connected circulant graphs with order n and degree 3 are given by using the k-diameter dk (x, y).

  13. Promising Poly(ε-caprolactone Composite Reinforced with Weft-Knitted Polyester for Small-Diameter Vascular Graft Application

    Directory of Open Access Journals (Sweden)

    Fu-Jun Wang

    2014-01-01

    Full Text Available The present study was designed to improve the mechanical performance of a small-diameter vascular prosthesis made from a flexible membrane of poly(ε-caprolactone (PCL. PCL reinforcement was achieved by embedding a tubular fabric knitted from polyethylene terephthalate (PET yarns within the freeze-dried composite structure. The knitting density of PET fabric influenced the mechanical properties of the new vascular graft. Results showed that the composite prototype has good mechanical properties, water permeability, elastic recovery, and suture retention strength. Increases in loop density increased compressive strength and suture retention strength and decreased elastic recovery. The new composite prototype vascular graft has promising potential applications in clinics because of its excellent mechanical properties.

  14. Study of in vitro RBCs membrane elasticity with AOD scanning optical tweezers.

    Science.gov (United States)

    Song, Huadong; Liu, Ying; Zhang, Bin; Tian, Kangzhen; Zhu, Panpan; Lu, Hao; Tang, Qi

    2017-01-01

    The elasticity of red cell membrane is a critical physiological index for the activity of RBC. Study of the inherent mechanism for RBCs membrane elasticity transformation is attention-getting all along. This paper proposes an optimized measurement method of erythrocytes membrane shear modulus incorporating acousto-optic deflector (AOD) scanning optical tweezers system. By use of this method, both membrane shear moduli and sizes of RBCs with different in vitro times were determined. The experimental results reveal that the RBCs membrane elasticity and size decline with in vitro time extension. In addition, semi quantitative measurements of S-nitrosothiol content in blood using fluorescent spectrometry during in vitro storage show that RBCs membrane elasticity change is positively associated with the S-nitrosylation level of blood. The analysis considered that the diminished activity of the nitric oxide synthase makes the S-nitrosylation of in vitro blood weaker gradually. The main reason for worse elasticity of the in vitro RBCs is that S-nitrosylation effect of spectrin fades. These results will provide a guideline for further study of in vitro cells activity and other clinical applications.

  15. Euler-Lagrange Elasticity: elasticity without stress or strain

    Science.gov (United States)

    Hardy, Humphrey

    2014-03-01

    A Euler-Lagrange (E-L) approach to elasticity is proposed that produces differential equations of elasticity without the need to define stress or strain tensors. The positions of the points within the body are the independent parameters instead of strain. Force replaces stress. The advantage of this approach is that the E-L differential equations are the same for both infinitesimal and finite deformations. Material properties are expressed in terms of the energy of deformation. The energy is expressed as a function of the principal invariants of the deformation gradient tensor. This scalar invariant representation of the energy of deformation enters directly into the E-L differential equations so that there is no need to define fourth order tensor material properties. By experimentally measuring the force and displacement of materials the functional form of the energy of deformation can be determined. The E-L differential equations can be input directly into finite element, finite difference, or other numerical models. If desired, stress and stain can be calculated as dependent parameters.

  16. Blood Donation

    Science.gov (United States)

    Tests and Procedures Blood donation By Mayo Clinic Staff Blood donation is a voluntary procedure. You agree to have blood drawn so that it can ... have a disease that requires blood components. Blood donation makes all of this possible. There are several ...

  17. Multi-scale imaging and elastic simulation of carbonates

    Science.gov (United States)

    Faisal, Titly Farhana; Awedalkarim, Ahmed; Jouini, Mohamed Soufiane; Jouiad, Mustapha; Chevalier, Sylvie; Sassi, Mohamed

    2016-05-01

    Digital Rock Physics (DRP) is an emerging technology that can be used to generate high quality, fast and cost effective special core analysis (SCAL) properties compared to conventional experimental techniques and modeling techniques. The primary workflow of DRP conssits of three elements: 1) image the rock sample using high resolution 3D scanning techniques (e.g. micro CT, FIB/SEM), 2) process and digitize the images by segmenting the pore and matrix phases 3) simulate the desired physical properties of the rocks such as elastic moduli and velocities of wave propagation. A Finite Element Method based algorithm, that discretizes the basic Hooke's Law equation of linear elasticity and solves it numerically using a fast conjugate gradient solver, developed by Garboczi and Day [1] is used for mechanical and elastic property simulations. This elastic algorithm works directly on the digital images by treating each pixel as an element. The images are assumed to have periodic constant-strain boundary condition. The bulk and shear moduli of the different phases are required inputs. For standard 1.5" diameter cores however the Micro-CT scanning reoslution (around 40 μm) does not reveal smaller micro- and nano- pores beyond the resolution. This results in an unresolved "microporous" phase, the moduli of which is uncertain. Knackstedt et al. [2] assigned effective elastic moduli to the microporous phase based on self-consistent theory (which gives good estimation of velocities for well cemented granular media). Jouini et al. [3] segmented the core plug CT scan image into three phases and assumed that micro porous phase is represented by a sub-extracted micro plug (which too was scanned using Micro-CT). Currently the elastic numerical simulations based on CT-images alone largely overpredict the bulk, shear and Young's modulus when compared to laboratory acoustic tests of the same rocks. For greater accuracy of numerical simulation prediction, better estimates of moduli inputs

  18. Wave propagation in elastic solids

    CERN Document Server

    Achenbach, Jan

    1984-01-01

    The propagation of mechanical disturbances in solids is of interest in many branches of the physical scienses and engineering. This book aims to present an account of the theory of wave propagation in elastic solids. The material is arranged to present an exposition of the basic concepts of mechanical wave propagation within a one-dimensional setting and a discussion of formal aspects of elastodynamic theory in three dimensions, followed by chapters expounding on typical wave propagation phenomena, such as radiation, reflection, refraction, propagation in waveguides, and diffraction. The treat

  19. Wave motion in elastic solids

    CERN Document Server

    Graff, Karl F

    1991-01-01

    This highly useful textbook presents comprehensive intermediate-level coverage of nearly all major topics of elastic wave propagation in solids. The subjects range from the elementary theory of waves and vibrations in strings to the three-dimensional theory of waves in thick plates. The book is designed not only for a wide audience of engineering students, but also as a general reference for workers in vibrations and acoustics. Chapters 1-4 cover wave motion in the simple structural shapes, namely strings, longitudinal rod motion, beams and membranes, plates and (cylindrical) shells. Chapter

  20. Variable Joint Elasticities in Running

    Science.gov (United States)

    Peter, Stephan; Grimmer, Sten; Lipfert, Susanne W.; Seyfarth, Andre

    In this paper we investigate how spring-like leg behavior in human running is represented at joint level. We assume linear torsion springs in the joints and between the knee and the ankle joint. Using experimental data of the leg dynamics we compute how the spring parameters (stiffness and rest angles) change during gait cycle. We found that during contact the joints reveal elasticity with strongly changing parameters and compare the changes of different parameters for different spring arrangements. The results may help to design and improve biologically inspired spring mechanisms with adjustable parameters.

  1. Threadlike bundle of tubules running inside blood vessels New anatomical structure

    CERN Document Server

    Jiang, X; Shin, H; Lee, B; Choi, C; Soh, K; Cheun, B; Baik, K; Soh, K; Jiang, Xiaowen; Kim, Hee-kyeong; Shin, Hak-soo; Lee, Byong-chon; Choi, Chunho; Soh, Kyung-soon; Cheun, Byeung-soo; Baik, Ku-youn; Soh, Kwang-sup

    2002-01-01

    According to current anatomy, the arteries and veins do not have threadlike structures running inside the vessels. Despite such prevailing knowledge here we report on observation of a novel structure inside the blood vessels of rats and rabbits, which is a semi-transparent elastic bundle of tubules whose diameters are of 10$\\mu$m order. This is a rediscovery of the Bong Han ducts1,2 which have not been confirmed because the observing method was not known. We found a new procedure of observing the intra blood vessel ducts (IBVD) which are too thin, fragile, and semi-transparent to be detected in ordinary surgical operation. The method we contrived is to let blood be coagulated around the IBVD so that they become thick and strong by intravenous injection of 10 per cent dextrose solution at the vena femoralis. A piece of thickened IBVD sample is treated with urokinase to remove blood clots and the thin thread of IBVD is embedded inside of a string of fibrin

  2. Development of a lower extremity wearable exoskeleton with double compact elastic module: preliminary experiments

    Directory of Open Access Journals (Sweden)

    Y. Long

    2017-08-01

    Full Text Available In this paper, a double compact elastic module is designed and implemented in the lower extremity exoskeleton. The double compact elastic module is composed of two parts, i.e., physical human robot interaction (pHRI measurement and the elastic actuation system (EAS, which are called proximal elastic module (PEM and distal elastic module (DEM respectively. The PEM is used as the pHRI information collection device while the DEM is used as the compliance device. A novel compact parallelogram-like structure based torsional spring is designed and developed. An iterative finite element analysis (FEA based optimization process was conducted to find the optimal parameters in the search space. In the PEM, the designed torsional spring has an outer circle with a diameter of 60 mm and an inner hole with a diameter of 12 mm, while in the DEM, the torsional spring has the outer circle with a diameter of 80 mm and the inner circle with a diameter of 16 mm. The torsional spring in the PEM has a thickness of 5 mm and a weight of 60 g, while that in the DEM has a thickness of 10 mm and a weight of 80 g. The double compact elastic module prototype is embedded in the mechanical joint directly. Calibration experiments were conducted on those two elastic modules to obtain the linear torque versus angle characteristic. The calibration experimental results show that this torsional spring in the PEM has a stiffness of 60.2 Nm rad−1, which is capable of withstanding a maximum torque of 4 Nm, while that in the DEM has a stiffness of 80.2 Nm rad−1, which is capable of withstanding a maximum torque of 30 Nm. The experimental results and the simulation data show that the maximum resultant errors are 6 % for the PEM and 4 % for the DEM respectively. In this paper, an assumed regression algorithm is used to learn the human motion intent (HMI based on the pHRI collection. The HMI is defined as the angular position of the human limb joint. A

  3. Computation of Modulus of Elasticity of Concrete

    Directory of Open Access Journals (Sweden)

    Onwuka, D.O

    2013-09-01

    Full Text Available - In this presentation, a computer based method which uses a set of algebraic equations and statistical data, were used to compute concrete mixes for prescribeable elastic concrete modulus, and vice versa. The computer programs based on Simplex and Regression theories can be used to predict several mix proportions for obtaining a desired modulus of elasticity of concrete made from crushed granite rock and other materials. The modulus of elasticity of concrete predicted by these programs agreed with experimentally obtained values. The programs are easy and inexpensive to use, and give instant and accurate results. For example, if the modulus of elasticity is specified as input, the computer instantly prints out all possible concrete mix ratios that can yield concrete having the specified elastic modulus. When the concrete mix ratio is specified as input, the computer quickly prints out the elastic modulus of the concrete obtainable from a given concrete mix ratio.

  4. ELASTIC: A Large Scale Dynamic Tuning Environment

    Directory of Open Access Journals (Sweden)

    Andrea Martínez

    2014-01-01

    Full Text Available The spectacular growth in the number of cores in current supercomputers poses design challenges for the development of performance analysis and tuning tools. To be effective, such analysis and tuning tools must be scalable and be able to manage the dynamic behaviour of parallel applications. In this work, we present ELASTIC, an environment for dynamic tuning of large-scale parallel applications. To be scalable, the architecture of ELASTIC takes the form of a hierarchical tuning network of nodes that perform a distributed analysis and tuning process. Moreover, the tuning network topology can be configured to adapt itself to the size of the parallel application. To guide the dynamic tuning process, ELASTIC supports a plugin architecture. These plugins, called ELASTIC packages, allow the integration of different tuning strategies into ELASTIC. We also present experimental tests conducted using ELASTIC, showing its effectiveness to improve the performance of large-scale parallel applications.

  5. Donating Blood

    Science.gov (United States)

    ... can't get an infection or disease from giving blood. The needles and other equipment used are sterile ... part of blood (plasma) within 72 hours after giving blood. It generally takes about 4–8 weeks to ...

  6. Donating Blood

    Science.gov (United States)

    ... Can Get Weight Loss Surgery? Choosing the Right Sport for You Shyness Donating ... Red Cross, there's a 97% chance that someone you know will need a blood transfusion. Blood donors — especially donors with certain blood types — are always ...

  7. Mean particle diameters: from statistical definition to physical understanding

    NARCIS (Netherlands)

    Alderliesten, M.

    2008-01-01

    Mean particle diameters are important for the science of particulate systems. This thesis deals with a definition system for these mean diameters, called Moment-Ratio (M-R) definition system, and provides a general statistical and physical basis. Also, the current DIN/ISO definition system is discus

  8. Effect of flow rate on diameter of electrospun nanoporous fibers

    Directory of Open Access Journals (Sweden)

    Tang Xiao-Peng

    2014-01-01

    Full Text Available The effect of flow rate on the diameter of the charged jet in the electrospinning process is studied theoretically. The obtained theoretical results offer in-depth physical understanding and mechanism of nanoporous fibers. It also reveals that the morphology and diameter of nanoporous microspheres can be controlled by the flow rate.

  9. Multi-spectral photoacoustic elasticity tomography

    Science.gov (United States)

    Liu, Yubin; Yuan, Zhen

    2016-01-01

    The goal of this work was to develop and validate a spectrally resolved photoacoustic imaging method, namely multi-spectral photoacoustic elasticity tomography (PAET) for quantifying the physiological parameters and elastic modulus of biological tissues. We theoretically and experimentally examined the PAET imaging method using simulations and in vitro experimental tests. Our simulation and in vitro experimental results indicated that the reconstructions were quantitatively accurate in terms of sizes, the physiological and elastic properties of the targets. PMID:27699101

  10. Study on elastic modulus of individual ferritin

    Institute of Scientific and Technical Information of China (English)

    ZHANG JinHai; CUI ChengYi; ZHOU XingFei

    2009-01-01

    The mechanical property of individual ferriUn was measured with force-volume mapping (FV) under contact mode of atomic force microscopy (AFM) in this work. The elastic modulus of individual ferritin was estimated by the Hertz mode. The estimated value of the elastic modulus of individual ferritin was about 250-800 MPs under a small deformation. In addition, the elastic modulus of individual ferritin was compared with that of the colloid gold nanoparticle.

  11. Continuously-Variable Series-Elastic Actuator

    OpenAIRE

    Mooney, Luke M.; Herr, Hugh M.

    2013-01-01

    Actuator efficiency is an important factor in the design of powered leg prostheses, orthoses, exoskeletons, and legged robots. A continuously-variable series-elastic actuator (CV-SEA) is presented as an efficient actuator for legged locomotion. The CV-SEA implements a continuously-variable transmission (CVT) between a motor and series elastic element. The CVT reduces the torque seen at the motor and allows the motor to operate in speed regimes of higher efficiency, while the series-elastic el...

  12. Eulerian formulation of elastic rods

    Science.gov (United States)

    Huynen, Alexandre; Detournay, Emmanuel; Denoël, Vincent

    2016-06-01

    In numerous biological, medical and engineering applications, elastic rods are constrained to deform inside or around tube-like surfaces. To solve efficiently this class of problems, the equations governing the deflection of elastic rods are reformulated within the Eulerian framework of this generic tubular constraint defined as a perfectly stiff normal ringed surface. This reformulation hinges on describing the rod-deformed configuration by means of its relative position with respect to a reference curve, defined as the axis or spine curve of the constraint, and on restating the rod local equilibrium in terms of the curvilinear coordinate parametrizing this curve. Associated with a segmentation strategy, which partitions the global problem into a sequence of rod segments either in continuous contact with the constraint or free of contact (except for their extremities), this re-parametrization not only trivializes the detection of new contacts but also transforms these free boundary problems into classic two-points boundary-value problems and suppresses the isoperimetric constraints resulting from the imposition of the rod position at the extremities of each rod segment.

  13. Pneumatic Variable Series Elastic Actuator.

    Science.gov (United States)

    Zheng, Hao; Wu, Molei; Shen, Xiangrong

    2016-08-01

    Inspired by human motor control theory, stiffness control is highly effective in manipulation and human-interactive tasks. The implementation of stiffness control in robotic systems, however, has largely been limited to closed-loop control, and suffers from multiple issues such as limited frequency range, potential instability, and lack of contribution to energy efficiency. Variable-stiffness actuator represents a better solution, but the current designs are complex, heavy, and bulky. The approach in this paper seeks to address these issues by using pneumatic actuator as a variable series elastic actuator (VSEA), leveraging the compressibility of the working fluid. In this work, a pneumatic actuator is modeled as an elastic element with controllable stiffness and equilibrium point, both of which are functions of air masses in the two chambers. As such, for the implementation of stiffness control in a robotic system, the desired stiffness/equilibrium point can be converted to the desired chamber air masses, and a predictive pressure control approach is developed to control the timing of valve switching to obtain the desired air mass while minimizing control action. Experimental results showed that the new approach in this paper requires less expensive hardware (on-off valve instead of proportional valve), causes less control action in implementation, and provides good control performance by leveraging the inherent dynamics of the actuator.

  14. Reliable Diameter Control of Carbon Nanotube Nanobundles Using Withdrawal Velocity

    Science.gov (United States)

    Shin, Jung Hwal; Kim, Kanghyun; An, Taechang; Choi, WooSeok; Lim, Geunbae

    2016-09-01

    Carbon nanotube (CNT) nanobundles are widely used in nanoscale imaging, fabrication, and electrochemical and biological sensing. The diameter of CNT nanobundles should be controlled precisely, because it is an important factor in determining electrode performance. Here, we fabricated CNT nanobundles on tungsten tips using dielectrophoresis (DEP) force and controlled their diameters by varying the withdrawal velocity of the tungsten tips. Withdrawal velocity pulling away from the liquid-air interface could be an important, reliable parameter to control the diameter of CNT nanobundles. The withdrawal velocity was controlled automatically and precisely with a one-dimensional motorized stage. The effect of the withdrawal velocity on the diameter of CNT nanobundles was analyzed theoretically and compared with the experimental results. Based on the attachment efficiency, the withdrawal velocity is inversely proportional to the diameter of the CNT nanobundles; this has been demonstrated experimentally. Control of the withdrawal velocity will play an important role in fabricating CNT nanobundles using DEP phenomena.

  15. Superresolution measurement of nanofiber diameter by modes beating

    Science.gov (United States)

    Fenton, E. F.; Solano, P.; Hoffman, J. E.; Orozco, L. A.; Rolston, S. L.; Fatemi, F. K.

    2016-05-01

    Nanofibers are becoming an important tool in quantum information technologies for coupling photonics systems to atomic systems. Nondestructive techniques for characterizing these nanofibers prior to integration into an apparatus are desirable. In this work, we probe the light propagating in a fused silica optical nanofiber (750-nm-diameter) by coupling it evanescently to a 6- μm-diameter microfiber that is scanned along the nanofiber length. This technique is capable of observing all possible beat lengths among different propagating modes. The beat lengths are strongly dependent on the nanofiber diameter and refractive index of the fiber. The steep dependence has enabled measurements of the fiber diameter with sub-Angstrom sensitivity. The diameter extracted from the beat length measurements agrees with a measurement made using scanning electron microscopy. Work supported by NSF.

  16. Elastic moduli of pyrope rich garnets

    Science.gov (United States)

    Pandey, B. K.; Pandey, A. K.; Singh, C. K.

    2013-06-01

    The elastic properties of minerals depend on its composition, crystal structure, temperature and level of defects. The elastic parameters are important for the interpretation of the structure and composition of the garnet rich family. In present work we have calculated the elastic moduli such as isothermal bulk modulus, Young's modulus and Shear modulus over a wide range of temperature from 300 K to 1000 K by using Birch EOS and Poirrier Tarantola equation of state. The obtained results are compared with the experimental results obtained by measuring the elastic moduli of single crystal. The calculated results show that the logarithmic isothermal EOS does not cooperate well with experimental results.

  17. Elastic properties of solids at high pressure

    Science.gov (United States)

    Vekilov, Yu Kh; Krasilnikov, O. M.; Lugovskoy, A. V.

    2015-11-01

    This review examines the elastic response of solids under load. The definitions of isothermal and adiabatic elastic constants of ( n≥2) for a loaded crystal are given. For the case of hydrostatic pressure, two techniques are proposed for calculating the second-, third-, and fourth-order elastic constants from the energy-strain and stress-strain relations. As an example, using the proposed approach within the framework of the density functional theory, the second- to fourth-order elastic constants of bcc tungsten are calculated for the pressure range of 0-600 GPa.

  18. Application Service Program (ASP Price Elasticities

    Directory of Open Access Journals (Sweden)

    Hong Jaeweon

    2010-06-01

    Full Text Available Although the price elasticities for off-line industry are well documented in academic field, the report of price elasticities for on-line to a given brand or industry in practice have beenrelatively rare. The researcher aims to try to full this gap by applying a price response function to Home Trading System’s on-line transaction data for the first time in Korean securities market. The different price elasticities among seven brands were found from -0.819 to -1.811. These results suggested that marketers should understand the price elasticity of their own HTS, before making a price decision.

  19. Faraday wave lattice as an elastic metamaterial.

    Science.gov (United States)

    Domino, L; Tarpin, M; Patinet, S; Eddi, A

    2016-05-01

    Metamaterials enable the emergence of novel physical properties due to the existence of an underlying subwavelength structure. Here, we use the Faraday instability to shape the fluid-air interface with a regular pattern. This pattern undergoes an oscillating secondary instability and exhibits spontaneous vibrations that are analogous to transverse elastic waves. By locally forcing these waves, we fully characterize their dispersion relation and show that a Faraday pattern presents an effective shear elasticity. We propose a physical mechanism combining surface tension with the Faraday structured interface that quantitatively predicts the elastic wave phase speed, revealing that the liquid interface behaves as an elastic metamaterial.

  20. Faraday wave lattice as an elastic metamaterial

    CERN Document Server

    Domino, L; Patinet, Sylvain; Eddi, A

    2016-01-01

    Metamaterials enable the emergence of novel physical properties due to the existence of an underlying sub-wavelength structure. Here, we use the Faraday instability to shape the fluid-air interface with a regular pattern. This pattern undergoes an oscillating secondary instability and exhibits spontaneous vibrations that are analogous to transverse elastic waves. By locally forcing these waves, we fully characterize their dispersion relation and show that a Faraday pattern presents an effective shear elasticity. We propose a physical mechanism combining surface tension with the Faraday structured interface that quantitatively predicts the elastic wave phase speed, revealing that the liquid interface behaves as an elastic metamaterial.

  1. Elastic properties, strength and damage tolerance of pultruded composites

    Science.gov (United States)

    Saha, Mrinal Chandra

    Pultruded composites are candidate materials for civil engineering infrastructural applications due their higher corrosion resistance and lower life cycle cost. Efficient use of materials like structural members requires thorough understanding of the mechanism that affects their response. The present investigation addresses the modeling and characterization of E-glass fiber/polyester resin matrix pultruded composites in the form of sheets of various thicknesses. The elastic constants were measured using static, vibration and ultrasonic methods. Two types of piezoelectric crystals were used in ultrasonic measurements. Finally, the feasibility of using a single specimen, in the form of a circular disk, was shown in measuring all the elastic constants using ultrasonic technique. The effects of stress gradient on tensile strength were investigated. A large number of specimens, parallel and transverse to the pultrusion direction, were tested in tension, 3-point flexure, and 4-point flexure. A 2-parameter Weibull model was applied to predict the tensile strength from the flexure tests. The measured and Weibull-predicted ratios did not show consistent agreement. Microstructural observations suggested that the flaw distribution in the material was not uniform, which appears to be a basic requirement for the Weibull distribution. Compressive properties were measured using a short-block compression test specimen of 44.4-mm long and 25.4-mm wide. Specimens were tested at 0°, 30°, 45°, 60° and 90° orientations. The compression test specimen was modeled using 4-noded isoparametric layered plate and shell elements. The predicted elastic properties for the roving layer and the continuous strand mat layer was used for the finite element study. The damage resistance and damage tolerance were investigated experimentally. Using a quasi-static indentation loading, damage was induced at various incrementally increased force levels to investigate the damage growth process. Damage

  2. Diameter of common bile duct: what are the predicting factors?

    Directory of Open Access Journals (Sweden)

    Atoosa Adibi

    2007-07-01

    Full Text Available

    BACKGROUND: This was a study to determine the correlation between the common bile duct (CBD diameter and demographic data, fasting, and the history of opium addiction.
    METHODS: This was a cross-sectional study on 375 patients (>16 years old including 219 females and 156 males. They had no evident hepatobiliary or pancreatic disease and underwent abdominopelvic ultrasonography for measurement of their CBD diameter. Ultrasound (US was performed to measure CBD diameter at the porta hepatis (proximal part and behind the head of the pancreas (distal part. Correlation coefficients for the association between CBD diameter and predictive factors were calculated. t-test was applied to compare the means between the groups.
    RESULTS: The mean CBD diameter (1 standard deviation, in proximal and distal parts were 3.64 mm (±1.2 and 3.72 mm (±1.2, respectively. The CBD diameters (proximal and distal were significantly (P<0.05 correlated with age (r = 0.55 and 0.54, respectively, BMI (r = 0.25 and 0.27, respectively and portal vein diameter (r = 0.24 and 0.22, respectively. Distal diameter of CBD was significantly larger in opium addicts (5.66 ± 2.65 in comparison with non addicts (3.68 ± 1.17, P = 0.04.
    CONCLUSIONS: CBD diameter associates with age, BMI, portal vein diameter and opium addiction. CBD dilatation, if it can not be explained by age, opium usage or large BMI, should be evaluated further to rule out obstruction.
    KEY WORDS: Common bile duct, predicting factors, ultrasonography.

  3. Ultrasonic measurement of the moduli of elasticity of refractory materials at high temperatures

    Science.gov (United States)

    Fargeot, D.; Gault, C.; Platon, F.

    1980-02-01

    A method of ultrasonic measurement of moduli of elasticity of refractory materials up to temperatures of the order of 2000 K is described. The use of magnetostrictive transducers allows operation in the 150-350 kHz frequency range of filamentary test samples with a diameter of about 2 mm and a length of 40-50 mm. Two practical examples are considered, for alpha alumina and for gamma alumina obtained by plasma torch projection.

  4. Measurement of Elastic Modulus and Vickers Hardness of Surround Bone Implant Using Dynamic Microindentation - Parameters Definition

    OpenAIRE

    Soares,Priscilla Barbosa Ferreira; Nunes,Sarah Arantes; Franco,Sinésio Domingues; Pires, Raphael Rezende; Zanetta-Barbosa,Darceny; Soares, Carlos José

    2014-01-01

    The clinical performance of dental implants is strongly defined by biomechanical principles. The aim of this study was to quantify the Vicker's hardness (VHN) and elastic modulus (E) surround bone to dental implant in different regions, and to discuss the parameters of dynamic microindantion test. Ten cylindrical implants with morse taper interface (Titamax CM, Neodent; 3.5 mm diameter and 7 mm a height) were inserted in rabbit tibia. The mechanical properties were analyzed using microhardnes...

  5. Water holding as determinant for the elastically stored energy in protein-based gels

    NARCIS (Netherlands)

    Pouvreau, L.A.M.; Wijlen, van Emke; Klok, Jan; Urbonaite, V.; Munialo, C.D.; Jongh, de H.H.J.

    2016-01-01

    To evaluate the importance of the water holding capacity for the elastically stored energy of protein gels, a range of gels were created from proteins from different origin (plant: pea and soy proteins, and animal: whey, blood plasma, egg white proteins, and ovalbumin) varying in network morphology

  6. Elastic fiber regeneration in vitro and in vivo for treatment of experimental abdominal aortic aneurysm

    Institute of Scientific and Technical Information of China (English)

    XIONG Jiang; GUO Wei; WEI Ren; ZUO Shang-wei; LIU Xiao-ping; ZHANG Tao

    2013-01-01

    Background The pathological characteristics of abdominal aortic aneurysm (AAA) involved the regression of extracellular matrix (ECM) in aortic walls,especially elastic structure in medial layer.As the major structural protein of aorta,elastin contributes to the extensibility and elastic recoil of the vessels.We hypothesized that overexpression of elastin in vessel walls might regenerate the elastic structure of ECM,restore the elastic structure of the aneurysmal wall,and eventually lead to a reduction of aortic diameters (ADs) in an experimental model of AAA.Methods Tropoelastin (TE) of Sprague Dawley (SD) rat was synthesized by reverse transcription polymerase chain reaction and used to construct adneviral vectors containing elastin precursor protein (AdTE-GFP).Cultured vascular smooth muscle cells (VSMCs) from aortas of male SD rats were transfected with AdTE-GFP,AdGFP,adenoviral vector (AdNull),and phosphate buffered saline (PBS).Immunofluorescence staining was performed to determine the expression of elastin in transfected cells.The expression of elastic fibers in ECM of VSMCs transfected with AdTE-GFP were detected by fluorescence microscopy and transmission electron microscopy (TEM) at 1,3,and 5 days following gene transfer.The AAA vessel walls were infused with AdTE-GFP or an empty AdNull,or PBS directly into the aneurysmal lumen.ADs of the aneurysms were compared in infused aortas.Formation of new elastic fibers in vivo was assessed by hematoxylin and eosin,and elastic von-Giesson staining.Recombinant elastin-GFP in vivo was identified by immunohistochemical staining.Results Elastic fibers were increased both in ECM of VSMC and in vessel walls after gene transfer.Histological studies revealed that the AdTE-GFP-transduced aortas had elastic fiber regeneration in the aneurysmal walls.The AdTE-GFP-transduced aortas showed a decreased AD (23.04%±14.49%,P <0.01) in AAA vessel walls.Conclusions Elastic fibers have been successfully overexpressed both in

  7. Vibration of an Elastic Circular Plate on an Elastic Half Space

    DEFF Research Database (Denmark)

    Krenk, Steen; Schmidt, H.

    1981-01-01

    The axisymmetric problem of a vibrating elastic plate on an elastic half space is solved by a direct method, in which the contact stresses and the normal displacements of the plate are taken as the unknown functions. First, the influence functions that give the displacements in terms...... influence from the elastic properties of the plate....

  8. Association between axial length and horizontal and vertical globe diameters.

    Science.gov (United States)

    Jonas, Jost B; Ohno-Matsui, Kyoko; Holbach, Leonard; Panda-Jonas, Songhomitra

    2017-02-01

    To assess relationships between axial length and the horizontal and vertical globe diameters. The study consisted of enucleated human eyes. The horizontal, vertical, and sagittal diameters were measured. The study included 135 globes removed because of malignant uveal melanoma (111 globes) or end-stage painful glaucoma (n = 24 eyes). Mean axial, horizontal, and vertical diameters were 24.6 ± 2.6 mm (range: 20-35 mm), 23.7 ± 1.4 mm (range: 21-29 mm) and 23.7 ± 1.4 mm (range: 20-29 mm) respectively. The horizontal diameter and vertical diameter did not differ significantly (P = 0.92), while both were significantly (P globe diameter (P globe diameter = 0.84 × horizontal globe diameter + 3.69). The axial diameter was significantly (P 24 mm, the horizontal and vertical globe diameter increased by a lower amount of 0.19 and 0.21 mm, respectively, for each mm increase in axial diameter. Myopic enlargement of the globe beyond an axial length of 24 mm takes place predominantly in the sagittal axis, leading to a change in the globe form from a sphere to an elongated form. It fits with the notion that myopic elongation may occur by an elongation of the eye walls in regions close to the globe's equator.

  9. Blood Flow in the Microcirculation

    Science.gov (United States)

    Secomb, Timothy W.

    2017-01-01

    The microcirculation is an extensive network of microvessels that distributes blood flow throughout living tissues. Reynolds numbers are much less than 1, and the equations of Stokes flow apply. Blood is a suspension of cells with dimensions comparable to microvessel diameters. Highly deformable red blood cells, which transport oxygen, have a volume concentration (hematocrit) of 40–45% in humans. In the narrowest capillaries, these cells move in single file with a surrounding lubricating layer of plasma. In larger vessels, the red blood cells migrate toward the centerline, reducing the resistance to blood flow. Vessel walls are coated with a layer of macromolecules that restricts flow. At diverging bifurcations, hematocrit is not evenly distributed in the downstream vessels. Other particles are driven toward the walls by interactions with red blood cells. These physiologically important phenomena are discussed here from a fluid mechanical perspective.

  10. Measurement of fetal biparietal diameter in owl monkeys (Aotus nancymaae).

    Science.gov (United States)

    Schuler, A Michele; Brady, Alan G; Tustin, George W; Parks, Virginia L; Morris, Chris G; Abee, Christian R

    2010-09-01

    Owl monkeys are New World primates frequently used in biomedical research. Despite the historical difficulty of breeding owl monkeys in captivity, several productive owl monkey breeding colonies exist currently. The animals in the colony we describe here are not timed-pregnant, and determination of gestational age is an important factor in prenatal care. Gestational age of human fetuses is often determined by using transabdominal measurements of fetal biparietal diameter. The purpose of this study was to correlate biparietal diameter measurements with gestational age in owl monkeys. We found that biparietal diameter can be used to accurately predict gestational age in owl monkeys.

  11. The Non-Homologous Nature of Solar Diameter Variations

    CERN Document Server

    Sofia, S; Demarque, P; Li, L; Thuillier, G; Sofia, Sabatino; Basu, Sarbani; Demarque, Pierre; Li, Linghuai; Thuillier, Gerard

    2005-01-01

    We show in this paper that the changes of the solar diameter in response to variations of large scale magnetic fields and turbulence are not homologous. For the best current model, the variation at the photospheric level is over 1000 times larger than the variation at a depth of 5 Mm, which is about the level at which f-mode solar oscillations determine diameter variations. This model is supported by observations that indicate larger diameter changes for high degree f-modes than for low degree f-modes, since energy of the former are concentrated at shallower layers than the latter.

  12. Tool electrode wear in electrical discharge of small diameter holes

    Directory of Open Access Journals (Sweden)

    Slătineanu Laurenţiu

    2017-01-01

    Full Text Available In the paper, the problem of obtaining small diameter holes in workpieces made of high speed steel by electrical discharge machining was formulated. A fulfil factorial experiment was designed and materialized, taking into consideration the tool electrode diameter, pulse on time and pulse off time as independent variables. The tool electrode wear was evaluated by means of the decrease of tool electrode mass and length. On the base of experimental results, power type empirical mathematical models were determined. One noticed the higher influence exerted by the too electrode diameter, whose increase determine the decrease of the tool electrode.

  13. Relationship of rolling bearing stiffness with diameter of roller

    Institute of Scientific and Technical Information of China (English)

    郭茂林; 王刚; 张瑞

    2002-01-01

    The theoretical formula of roller bearing stiffness is induced and compared with its empirical formula.In the experience formula the stiffness of roller bearing has nothing to do with the roller diameter. The relation-ship of roller bearing stiffness with roller diameter was studied using Hz contacting theory. It is concluded thatconclusion in experience formula is only approximate result of data processing under special conditions, and therelation between stiffness of roller bearing and roller diameter must be taken into consideration while designingor selecting roller bearings.

  14. Homogenization method for elastic materials

    Directory of Open Access Journals (Sweden)

    Seifrt F.

    2007-11-01

    Full Text Available In the paper we study the homogenization method and its potential for research of some phenomenons connected with periodic elastic materials. This method will be applied on partial differential equations that describe the deformation of a periodic composite material. The next part of the paper will deal with applications of the homogenization method. The importance of the method will be discussed more detailed for the exploration of the so called bandgaps. Bandgap is a phenomenon which may appear during vibrations of some periodically heterogeneous materials. This phenomenon is not only observable during vibrations for the aforementioned materials, but we may also observe similar effects by propagation of electromagnetic waves of heterogeneous dielectric medias.

  15. Mathematical methods for elastic plates

    CERN Document Server

    Constanda, Christian

    2014-01-01

    Mathematical models of deformation of elastic plates are used by applied mathematicians and engineers in connection with a wide range of practical applications, from microchip production to the construction of skyscrapers and aircraft. This book employs two important analytic techniques to solve the fundamental boundary value problems for the theory of plates with transverse shear deformation, which offers a more complete picture of the physical process of bending than Kirchhoff’s classical one.   The first method transfers the ellipticity of the governing system to the boundary, leading to singular integral equations on the contour of the domain. These equations, established on the basis of the properties of suitable layer potentials, are then solved in spaces of smooth (Hölder continuous and Hölder continuously differentiable) functions.   The second technique rewrites the differential system in terms of complex variables and fully integrates it, expressing the solution as a combination of complex ana...

  16. Wrinkling of Pressurized Elastic Shells

    KAUST Repository

    Vella, Dominic

    2011-10-01

    We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells are subject to a wrinkling instability. We study wrinkling in depth, presenting scaling laws for the critical indentation at which wrinkling occurs and the number of wrinkles formed in terms of the internal pressurization and material properties of the shell. These results are validated by numerical simulations. We show that the evolution of the wrinkle length with increasing indentation can be understood for highly pressurized shells from membrane theory. These results suggest that the position and number of wrinkles may be used in combination to give simple methods for the estimation of the mechanical properties of highly pressurized shells. © 2011 American Physical Society.

  17. Multidiscipline simulation of elastic manipulators

    Directory of Open Access Journals (Sweden)

    T. Rølvåg

    1992-10-01

    Full Text Available This paper contributes to multidiscipline simulation of elastic robot manipulators in FEDEM. All developments presented in this paper are based on the formulations in FEDEM, a simulation system developed by the authors which combines finite element, mechanism and control analysis. In order to establish this general simulation system as an efficient multidiscipline robot design tool a robot control system including a high level robot programming language, interpolation algorithms, path generation algorithms, forward and inverse kinematics, control systems, gear and transmission models are implemented. These new features provide a high level of integration between traditionally separate design disciplines from the very beginning of the design and optimization process. Several simulations have shown that high fidelity mathematical models can be derived and used as a basis for dynamic analysis and controller design in FEDEM.

  18. The visco-elastic multilayer program VEROAD

    NARCIS (Netherlands)

    Hopman, P.C.

    1996-01-01

    The mathematical principles and derivation of a linear visco-elastic multilayer computer program are described. The mathematical derivation is based on Fourier Transformation. The program is called VEROAD, which is an acronym for Visco-Elastic ROad Analysis Delft. The program allows calculation of p

  19. Acoustic signal analysis of underwater elastic cylinder

    Institute of Scientific and Technical Information of China (English)

    LI Xiukun; YANG Shi'e

    2001-01-01

    The echoes of underwater elastic cylinder comprise two types of acoustic components: Geometrical scattering waves and elastic scattering waves. The transfer function is appropriate to characterize the echo of targets. And the discrete wavelet transform of amplitude spectrum is presented and used to identify the resonant components of underwater targets.PACS numbers: 43.30, 43.60

  20. Celestial mechanics of elastic bodies II

    CERN Document Server

    Beig, Robert; Schmidt, Bernd G

    2016-01-01

    We construct time independent configurations describing a small elastic body moving in a circular orbit in the Schwarzschild spacetime. These configurations are relativistic versions of Newtonian solutions constructed by two of us (R.B.,B.G.S.). In the process we simplify and sharpen previous results of ours concerning elastic bodies in rigid rotation.

  1. Elastic least-squares reverse time migration

    KAUST Repository

    Feng, Zongcai

    2017-03-08

    We use elastic least-squares reverse time migration (LSRTM) to invert for the reflectivity images of P- and S-wave impedances. Elastic LSRTMsolves the linearized elastic-wave equations for forward modeling and the adjoint equations for backpropagating the residual wavefield at each iteration. Numerical tests on synthetic data and field data reveal the advantages of elastic LSRTM over elastic reverse time migration (RTM) and acoustic LSRTM. For our examples, the elastic LSRTM images have better resolution and amplitude balancing, fewer artifacts, and less crosstalk compared with the elastic RTM images. The images are also better focused and have better reflector continuity for steeply dipping events compared to the acoustic LSRTM images. Similar to conventional leastsquares migration, elastic LSRTM also requires an accurate estimation of the P- and S-wave migration velocity models. However, the problem remains that, when there are moderate errors in the velocity model and strong multiples, LSRTMwill produce migration noise stronger than that seen in the RTM images.

  2. Wave propagation in elastic layers with damping

    DEFF Research Database (Denmark)

    Sorokin, Sergey; Darula, Radoslav

    2016-01-01

    The conventional concepts of a loss factor and complex-valued elastic moduli are used to study wave attenuation in a visco-elastic layer. The hierarchy of reduced-order models is employed to assess attenuation levels in various situations. For the forcing problem, the attenuation levels are found...

  3. Solitary waves on nonlinear elastic rods. I

    DEFF Research Database (Denmark)

    Sørensen, Mads Peter; Christiansen, Peter Leth; Lomdahl, P. S.

    1984-01-01

    Acoustic waves on elastic rods with circular cross section are governed by improved Boussinesq equations when transverse motion and nonlinearity in the elastic medium are taken into account. Solitary wave solutions to these equations have been found. The present paper treats the interaction between...

  4. Simulation and control problems in elastic robots

    Science.gov (United States)

    Tadikonda, S. S. K.; Baruh, H.

    1989-01-01

    Computational issues associated with modeling and control of robots with revolute joints and elastic arms are considered. A manipulator with one arm and pinned at one end is considered to investigate various aspects of the modeling procedure and the model, and the effect of coupling between the rigid-body and the elastic motions. The rigid-body motion of a manipulator arm is described by means of a reference frame attached to the shadow beam, and the linear elastic operator denoting flexibility is defined with respect to this reference frame. The small elastic motion assumption coupled with the method of assumed modes is used to model the elasticity in the arm. It is shown that only terms up to quadratic in these model amplitudes need to be retained. An important aspect of the coupling between the rigid-body and the elastic motion is the centrifugal stiffening effect. This effect stiffens the elastic structure, as to be expected on physical grounds, gives rise to a time-varying inertia term for the rigid-body motion, and, in general, results in an effective inertia term smaller than the rigid-body inertia term. Simulation results are presented for an elastic beam pinned at one end and free at the other, and rotating in a horizontal plane, and control issues such as the order of the model, number of sensors, and modal extraction are examined within this context.

  5. 7 CFR 29.6013 - Elasticity.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Elasticity. 29.6013 Section 29.6013 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6013 Elasticity. The flexible, springy nature of the tobacco leaf...

  6. Monopoly price discrimination with constant elasticity demand

    OpenAIRE

    Aguirre Pérez, Iñaki; Cowan, Simon George

    2013-01-01

    This paper presents new results on the welfare e¤ects of third-degree price discrimination under constant elasticity demand. We show that when both the share of the strong market under uniform pricing and the elasticity di¤erence between markets are high enough,then price discrimination not only can increase social welfare but also consumer surplus.

  7. Monopoly price discrimination with constant elasticity demand

    OpenAIRE

    Aguirre Pérez, Iñaki; Cowan, Simon George

    2013-01-01

    This paper presents new results on the welfare e¤ects of third-degree price discrimination under constant elasticity demand. We show that when both the share of the strong market under uniform pricing and the elasticity di¤erence between markets are high enough,then price discrimination not only can increase social welfare but also consumer surplus.

  8. Microstrain-level measurement of third-order elastic constants applying dynamic acousto-elastic testing

    OpenAIRE

    Renaud, Guillaume; Talmant, Maryline; Marrelec, Guillaume

    2016-01-01

    International audience; The nonlinear elasticity of solids at the microstrain level has been recently studied by applying dynamic acousto-elastic testing. It is the analog of conventional quasi-static acousto-elastic experiments but the strain-dependence (or stress-dependence) of ultrasonic wave-speed is measured with an applied strain ranging from 10−7 to 10−5 and produced by a stationary elastic wave. In conventional quasi-static acousto-elastic experiments, the strain is applied in a quasi...

  9. Mechanical properties of biodegradable small-diameter chitosan artificial vascular prosthesis.

    Science.gov (United States)

    Kong, Xiaoying; Han, Baoqin; Wang, Haixia; Li, Hui; Xu, Wenhua; Liu, Wanshun

    2012-08-01

    Initial clinical feasibility with the small-diameter chitosan artificial vascular prosthesis has been reported previously. Here, we present the results of mechanical properties of artificial vascular prosthesis with 2, 3, and 4 mm inner diameter (ID) and compare some of the properties with the native blood vessel of dog femoral artery. Thickness wall measurement demonstrated the average wall thickness of the artificial vascular prosthesis with 2, 3, and 4 mm ID and the native blood vessel of the dog femoral artery with 3 mm ID were 0.54 ± 0.022 mm, 0.71 ± 0.032 mm, 0.79 ± 0.026 mm, and 0.67 ± 0.22 mm (n = 20). Water absorption rate of 226.02% ± 8.17%, 216.13% ± 4.86%, and 205.69% ± 4.34% were obtained from 2-, 3-, and 4-mm-diameter artificial vascular prosthesis (n = 12), respectively. Water osmotic pressure of the 2-, 3-, and 4-mm-diameter artificial vascular prosthesis was 39.25 ± 3.35 mmHg, 34.2 ± 4.54 mmHg, and 28.00 ± 2.72 mmHg (n = 20), respectively. Water osmotic amount of the 2-, 3-, and 4-cm-diameter artificial vascular prosthesis (n = 20) was 4.90 ± 0.47 mL/(min cm(2) ), 5.51 ± 0.21 mL/(min cm(2) ), and 6.24 ± 0.71 mL/(min cm(2) ), respectively. The ruptured stretching rate of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID and the native blood vessel was 1.59% ± 0.14%, 1.99% ± 0.24%, 2.52% ± 0.21%, and 32.16% ± 2.15%, respectively. The longitudinal tensile strength of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID and the native blood vessel was 8.58 ± 1.98 N, 19.75 ± 4.07 N, 22.92 ± 3.85 N, and 18.76 ± 2.05 N, respectively. The suture retention of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID and the native blood vessel in dry condition is 5.80 ± 0.51 N, 7.01 ± 0.32 N, 8.49 ± 0.56 N, and 7.92 ± 0.39 N, respectively. The suture retention of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID in wet condition is 3.87 ± 0.43 N, 4.73 ± 0.37 N, 5.63 ± 0

  10. Elastic modulus and viscoelastic properties of full thickness skin characterised at micro scales.

    Science.gov (United States)

    Crichton, Michael L; Chen, Xianfeng; Huang, Han; Kendall, Mark A F

    2013-03-01

    The recent emergence of micro-devices for vaccine delivery into upper layers of the skin holds potential for increased immune responses using physical means to target abundant immune cell populations. A challenge in doing this has been a limited understanding of the skin elastic properties at the micro scale (i.e. on the order of a cell diameter; ~10 μm). Here, we quantify skin's elastic properties at a micro-scale by fabricating customised probes of scales from sub- to super-cellular (0.5 μm-20 μm radius). We then probe full thickness skin; first with force-relaxation experiments and subsequently by elastic indentations. We find that skin's viscoelastic response is scale-independent: consistently a ~40% decrease in normalised force over the first second, followed by further 10% reduction over 10 s. Using Prony series and Hertzian contact analyses, we determined the strain-rate independent elastic moduli of the skin. A high scale dependency was found: the smallest probe encountered the highest elastic modulus (~30 MPa), whereas the 20 μm radius probe was lowest (below 1 MPa). We propose that this may be a result of the load distribution in skin facilitated by the hard corneocytes in the outermost skin layers, and softer living cell layers below. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Elastogenic protein expression of a highly elastic murine spinal ligament: the ligamentum flavum.

    Directory of Open Access Journals (Sweden)

    Jeffrey P Brown

    Full Text Available Spinal ligaments, such as the ligamentum flavum (LF, are prone to degeneration and iatrogenic injury that can lead to back pain and nerve dysfunction. Repair and regeneration strategies for these tissues are lacking, perhaps due to limited understanding of spinal ligament formation, the elaboration of its elastic fibers, maturation and homeostasis. Using immunohistochemistry and histology, we investigated murine LF elastogenesis and tissue formation from embryonic to mature postnatal stages. We characterized the spatiotemporal distribution of the key elastogenic proteins tropoelastin, fibrillin-1, fibulin-4 and lysyl oxidase. We found that elastogenesis begins in utero with the microfibril constituent fibrillin-1 staining intensely just before birth. Elastic fibers were first detected histologically at postnatal day (P 7, the earliest stage at which tropoelastin and fibulin-4 stained intensely. From P7 to P28, elastic fibers grew in diameter and became straighter along the axis. The growth of elastic fibers coincided with intense staining of tropoelastin and fibulin-4 staining, possibly supporting a chaperone role for fibulin-4. These expression patterns correlated with reported skeletal and behavioral changes during murine development. This immunohistochemical characterization of elastogenesis of the LF will be useful for future studies investigating mechanisms for elastogenesis and developing new strategies for treatment or regeneration of spinal ligaments and other highly elastic tissues.

  12. Traveling Lamb wave in elastic metamaterial layer

    Science.gov (United States)

    Shu, Haisheng; Xu, Lihuan; Shi, Xiaona; Zhao, Lei; Zhu, Jie

    2016-10-01

    The propagation of traveling Lamb wave in single layer of elastic metamaterial is investigated in this paper. We first categorized the traveling Lamb wave modes inside an elastic metamaterial layer according to different combinations (positive or negative) of effective medium parameters. Then the impacts of the frequency dependence of effective parameters on dispersion characteristics of traveling Lamb wave were studied. Distinct differences could be observed when comparing the traveling Lamb wave along an elastic metamaterial layer with one inside the traditional elastic layer. We further examined in detail the traveling Lamb wave mode supported in elastic metamaterial layer, when the effective P and S wave velocities were simultaneously imaginary. It was found that the effective modulus ratio is the key factor for the existence of special traveling wave mode, and the main results were verified by FEM simulations from two levels: the level of effective medium and the level of microstructure unit cell.

  13. Breakdown of elasticity in amorphous solids

    Science.gov (United States)

    Biroli, Giulio; Urbani, Pierfrancesco

    2016-12-01

    What characterizes a solid is the way that it responds to external stresses. Ordered solids, such as crystals, exhibit an elastic regime followed by a plastic regime, both understood microscopically in terms of lattice distortion and dislocations. For amorphous solids the situation is instead less clear, and the microscopic understanding of the response to deformation and stress is a very active research topic. Several studies have revealed that even in the elastic regime the response is very jerky at low temperature, resembling very much the response of disordered magnetic materials. Here we show that in a very large class of amorphous solids this behaviour emerges upon decreasing temperature, as a phase transition, where standard elastic behaviour breaks down. At the transition all nonlinear elastic moduli diverge and standard elasticity theory no longer holds. Below the transition, the response to deformation becomes history- and time-dependent.

  14. Porosity Assessment for Different Diameters of Coir Lignocellulosic Fibers

    Science.gov (United States)

    da Luz, Fernanda Santos; Paciornik, Sidnei; Monteiro, Sergio Neves; da Silva, Luiz Carlos; Tommasini, Flávio James; Candido, Verônica Scarpini

    2017-08-01

    The application of natural lignocellulosic fibers (LCFs) in engineering composites has increased interest in their properties and structural characteristics. In particular, the inherent porosity of an LCF markedly affects its density and the adhesion to polymer matrices. For the first time, both open and closed porosities of a natural LCF, for different diameter ranges, were assessed. Fibers extracted from the mesocarp of the coconut fruit were investigated by nondestructive methods of density measurements and x-ray microtomography (microCT). It was found that, for all diameter ranges, the closed porosity is significantly higher than the open porosity. The total porosity increases with diameter to around 60% for coir fibers with more than 503 μm in diameter. The amount and characteristics of these open and closed porosities were revealed by t test and Weibull statistics as well as by microCT.

  15. Study of Linearly Polarized Light Measuring Fiber Diameter

    Energy Technology Data Exchange (ETDEWEB)

    Liang Hong, E-mail: lianghong@cuc.edu.cn [School of science, Communication University of China 100024 (China)

    2011-02-01

    The letter discusses a new way to measure fiber diameters, studies the theory of measuring fiber radius using this way, carries out numerical simulation based on this and provides experiment method as well.

  16. Eddy sensors for small diameter stainless steel tubes.

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Jack L.; Morales, Alfredo Martin; Grant, J. Brian; Korellis, Henry James; LaFord, Marianne Elizabeth; Van Blarigan, Benjamin; Andersen, Lisa E.

    2011-08-01

    The goal of this project was to develop non-destructive, minimally disruptive eddy sensors to inspect small diameter stainless steel metal tubes. Modifications to Sandia's Emphasis/EIGER code allowed for the modeling of eddy current bobbin sensors near or around 1/8-inch outer diameter stainless steel tubing. Modeling results indicated that an eddy sensor based on a single axial coil could effectively detect changes in the inner diameter of a stainless steel tubing. Based on the modeling results, sensor coils capable of detecting small changes in the inner diameter of a stainless steel tube were designed, built and tested. The observed sensor response agreed with the results of the modeling and with eddy sensor theory. A separate limited distribution SAND report is being issued demonstrating the application of this sensor.

  17. Improved Design Basis for Laterally Loaded Large Diameter Pile

    DEFF Research Database (Denmark)

    Leth, Caspar Thrane

    of up-to-date facilities has been: Equipment for controlling centrifuge tests, data acquisition, preparation of test samples and equipment for and making of lateral load tests. The present research has been narrowed to investigate the static and cyclic behaviour of stiff piles with a diameter of 1-3 m...... on the structure and the productivity of the turbine. Current design practice for monopiles are based on p-y curves developed for slender piles with a diameter of 0.6 m. The focus on the structure stiffness has entailed a significant research on the soil-structure interaction for large diameter monopiles....... Comparison of the different approaches shows some discrepancy and conflicting statements, but the main findings can be summarized as: • The standard p-y curves are inadequate to describe the behaviour of lateral loaded large diameter rigid piles. • Initial stiffness of the p-y curves is depended...

  18. Pupil diameter reflects uncertainty in attentional selection during visual search

    Directory of Open Access Journals (Sweden)

    Joy J. Geng

    2015-08-01

    Full Text Available Pupil diameter has long been used as a metric of cognitive processing. However, recent advances suggest that the cognitive sources of change in pupil size may reflect LC-NE function and the calculation of unexpected uncertainty in decision processes (Aston-Jones & Cohen, 2005b; Yu & Dayan, 2005. In the current experiments, we explored the role of uncertainty in attentional selection on task-evoked changes in pupil diameter during visual search. We found that task-evoked changes in pupil diameter were related to uncertainty during attentional selection as measured by reaction time and performance accuracy (Experiments 1-2. Control analyses demonstrated that the results are unlikely to be due to error monitoring or response uncertainty. Our results suggest that pupil diameter can be used as an implicit metric of uncertainty in ongoing attentional selection requiring effortful control processes.

  19. Is ultrasonographically detected nodule diameter concordant with pathological tumor size?

    Science.gov (United States)

    Bilginer, Muhammet Cuneyt; Ozdemir, Didem; Baser, Husniye; Dogan, Hayriye Tatli; Yalcin, Abdussamed; Ersoy, Reyhan; Cakir, Bekir

    2017-06-01

    We aimed to compare preoperative ultrasonographical and postoperative histopathological diameters of differentiated thyroid cancer (DTC) lesions and investigate possible factors that can predict the discordance between two measurements. Data of patients with histopathologically confirmed DTC were reviewed retrospectively. Nodules evaluated by preoperative US were matched with histopathologically examined nodules. Incidental tumors and nodules that can not be matched in US and histopathology reports were excluded. Preoperative US diameter and postoperative histopathological size were compared and percentage difference between two measurements was calculated for each lesion. There were 607 DTC foci in 562 patients. Mean US diameter was significantly higher than histopathological diameter (21.0 ± 15.6 mm vs 17.3 ± 13.6, p size in 444 (73.1%), equal in 15 (2.5%) and lower in 148 (24.4%) nodules. Marginal irregularity was observed in 253 (57%) lesions with US diameter > tumor size and 108 (73%) lesions with US diameter size (p = 0.010). Rate of nodules with peripheral halo was higher in lesions with US diameter > tumor size (30.6% vs 20.3%, p = 0.015). In nodules with US diameter > tumor size, percentage difference was lower in nodules with microcalcification (p = 0.020) and higher in cytologically benign nodules (p size, size in a considerable ratio of DTCs. It might be helpful to consider this discordance while deciding surgical extent in these patients. Copyright © 2017 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.

  20. Minimum Orders of Eulerian Oriented Digraphs with Given Diameter

    Institute of Scientific and Technical Information of China (English)

    Yoomi RHO; Byeong Moon KIM; Woonjae HWANG; Byung Chul SONG

    2014-01-01

    A digraph D is oriented if it does not contain 2-cycles. If an oriented digraph D has a directed eulerian path, it is an oriented eulerian digraph. In this paper, when an oriented eulerian digraph D has minimum out-degree 2 and a diameter d, we find the minimum order of D. In addition, when D is 2-regular with diameter 4m (m≥2), we classify the extremal cases.

  1. Analytical solutions for elastic binary nanotubes of arbitrary chirality

    Science.gov (United States)

    Jiang, Lai; Guo, Wanlin

    2016-12-01

    Analytical solutions for the elastic properties of a variety of binary nanotubes with arbitrary chirality are obtained through the study of systematic molecular mechanics. This molecular mechanics model is first extended to chiral binary nanotubes by introducing an additional out-of-plane inversion term into the so-called stick-spiral model, which results from the polar bonds and the buckling of binary graphitic crystals. The closed-form expressions for the longitudinal and circumferential Young's modulus and Poisson's ratio of chiral binary nanotubes are derived as functions of the tube diameter. The obtained inversion force constants are negative for all types of binary nanotubes, and the predicted tube stiffness is lower than that by the former stick-spiral model without consideration of the inversion term, reflecting the softening effect of the buckling on the elastic properties of binary nanotubes. The obtained properties are shown to be comparable to available density functional theory calculated results and to be chirality and size sensitive. The developed model and explicit solutions provide a systematic understanding of the mechanical performance of binary nanotubes consisting of III-V and II-VI group elements.

  2. Force spectroscopy of complex biopolymers with heterogeneous elasticity

    Science.gov (United States)

    Valdman, David; Lopez, Benjamin J.

    2013-01-01

    Cellular biopolymers can exhibit significant compositional heterogeneities as a result of the non-uniform binding of associated proteins, the formation of microstructural defects during filament assembly, or the imperfect bundling of filaments into composite structures of variable diameter. These can lead to significant variations in the local mechanical properties of biopolymers along their length. Existing spectral analysis methods assume filament homogeneity and therefore report only a single average stiffness for the entire filament. However, understanding how local effects modulate biopolymer mechanics in a spatially resolved manner is essential to understanding how binding and bundling proteins regulate biopolymer stiffness and function in cellular contexts. Here, we present a new method to determine the spatially varying material properties of individual complex biopolymers from the observation of passive thermal fluctuations of the filament conformation. We develop new statistical mechanics-based approaches for heterogeneous filaments that estimate local bending elasticities as a function of the filament arc-length. We validate this methodology using simulated polymers with known stiffness distributions, and find excellent agreement between derived and expected values. We then determine the bending elasticity of microtubule filaments of variable composition generated by repeated rounds of tubulin polymerization using either GTP or GMPCPP, a nonhydrolyzable GTP analog. Again, we find excellent agreement between mechanical and compositional heterogeneities. PMID:24049545

  3. Nanoencapsulation of quercetin and resveratrol into elastic liposomes.

    Science.gov (United States)

    Cadena, Pabyton G; Pereira, Marcela A; Cordeiro, Rafaela B S; Cavalcanti, Isabella M F; Barros Neto, Benício; Pimentel, Maria do Carmo C B; Lima Filho, José Luiz; Silva, Valdinete L; Santos-Magalhães, Nereide S

    2013-02-01

    Based on the fact that quercetin (QUE) and resveratrol (RES) induce a synergic inhibition of the adipogenesis and increase apoptosis in adipocytes, and that sodium deoxycholate (SDC) has necrotic effects, the nanoencapsulation of QUE and RES into SDC-elastic liposomes is proposed as a new approach for dissolving the subcutaneous fat. The concentration of constituents and the effect of the drug incorporation into cyclodextrin inclusion complexes on the stability of QUE/RES-loaded liposomes were studied. The best liposomal formulation reduced the use of phosphatidylcholine and cholesterol in 17.7% and 68.4%, respectively. Liposomes presented a mean diameter of 149nm with a polydispersion index of 0.3. The zeta potential of liposomes was slightly negative (-13.3mV) due to the presence of SDC in the phospholipid bilayer. Encapsulation efficiency of QUE and RES into liposomes was almost 97%. To summarize, QUE/RES-loaded elastic liposomes are stable and suitable for subcutaneous injection, thereby providing a new strategy for reducing subcutaneous fat.

  4. Analytical solutions for elastic binary nanotubes of arbitrary chirality

    Science.gov (United States)

    Jiang, Lai; Guo, Wanlin

    2016-09-01

    Analytical solutions for the elastic properties of a variety of binary nanotubes with arbitrary chirality are obtained through the study of systematic molecular mechanics. This molecular mechanics model is first extended to chiral binary nanotubes by introducing an additional out-of-plane inversion term into the so-called stick-spiral model, which results from the polar bonds and the buckling of binary graphitic crystals. The closed-form expressions for the longitudinal and circumferential Young's modulus and Poisson's ratio of chiral binary nanotubes are derived as functions of the tube diameter. The obtained inversion force constants are negative for all types of binary nanotubes, and the predicted tube stiffness is lower than that by the former stick-spiral model without consideration of the inversion term, reflecting the softening effect of the buckling on the elastic properties of binary nanotubes. The obtained properties are shown to be comparable to available density functional theory calculated results and to be chirality and size sensitive. The developed model and explicit solutions provide a systematic understanding of the mechanical performance of binary nanotubes consisting of III-V and II-VI group elements.

  5. Catalytic growth of carbon nanotubes with large inner diameters

    Directory of Open Access Journals (Sweden)

    WEI REN ZHONG

    2005-02-01

    Full Text Available Carbon nanotubes (2.4 g/g catalyst, with large inner diameters were successfully synthesized through pyrolysis of methane on a Ni–Cu–Al catalyst by adding sodium carbonate into the carbon nanotubes growth system. The inner diameter of the carbon nanotubes prepared by this method is about 20–60 nm, while their outer diameter is about 40–80 nm. Transmission electron microscopy and X-ray diffraction were employed to investigate the morphology and microstructures of the carbon nanotubes. The analyses showed that these carbon nanotubes have large inner diameters and good graphitization. The addition of sodium carbonate into the reaction system brings about a slight decrease in the methane conversion and the yield of carbon. The experimental results showed that sodium carbonate is a mildly toxic material which influenced the catalytic activity of the Ni–Cu–Al catalyst and resulted in the formation of carbon nanotubes with large inner diameters. The growth mechanism of the carbon nanotubes with large inner diameters is discussed in this paper.

  6. Diameter dependence of thermoelectric power of semiconducting carbon nanotubes

    Science.gov (United States)

    Hung, Nguyen T.; Nugraha, Ahmad R. T.; Hasdeo, Eddwi H.; Dresselhaus, Mildred S.; Saito, Riichiro

    2015-10-01

    We calculate the thermoelectric power (or thermopower) of many semiconducting single wall carbon nanotubes (s-SWNTs) within a diameter range 0.5 -1.5 nm by using the Boltzmann transport formalism combined with an extended tight-binding model. We find that the thermopower of s-SWNTs increases as the tube diameter decreases. For some s-SWNTs with diameters less than 0.6 nm , the thermopower can reach a value larger than 2000 μ V /K at room temperature, which is about 6 to 10 times larger than that found in commonly used thermoelectric materials. The large thermopower values may be attributed to the one dimensionality of the nanotubes and to the presence of large band gaps of the small-diameter s-SWNTs. We derive an analytical formula to reproduce the numerical calculation of the thermopower and we find that the thermopower of a given s-SWNT is directly related with its band gap. The formula also explains the shape of the thermopower as a function of tube diameter, which looks similar to the shape of the so-called Kataura plot of the band gap dependence on tube diameter.

  7. Artificial blood

    Directory of Open Access Journals (Sweden)

    Sarkar Suman

    2008-01-01

    Full Text Available Artificial blood is a product made to act as a substitute for red blood cells. While true blood serves many different functions, artificial blood is designed for the sole purpose of transporting oxygen and carbon dioxide throughout the body. Depending on the type of artificial blood, it can be produced in different ways using synthetic production, chemical isolation, or recombinant biochemical technology. Development of the first blood substitutes dates back to the early 1600s, and the search for the ideal blood substitute continues. Various manufacturers have products in clinical trials; however, no truly safe and effective artificial blood product is currently marketed. It is anticipated that when an artificial blood product is available, it will have annual sales of over $7.6 billion in the United States alone.

  8. Artificial blood.

    Science.gov (United States)

    Sarkar, Suman

    2008-07-01

    Artificial blood is a product made to act as a substitute for red blood cells. While true blood serves many different functions, artificial blood is designed for the sole purpose of transporting oxygen and carbon dioxide throughout the body. Depending on the type of artificial blood, it can be produced in different ways using synthetic production, chemical isolation, or recombinant biochemical technology. Development of the first blood substitutes dates back to the early 1600s, and the search for the ideal blood substitute continues. Various manufacturers have products in clinical trials; however, no truly safe and effective artificial blood product is currently marketed. It is anticipated that when an artificial blood product is available, it will have annual sales of over $7.6 billion in the United States alone.

  9. Small-diameter prosthetic H-graft portacaval shunts in the treatment of portal hypertension

    Institute of Scientific and Technical Information of China (English)

    胡何节; 许戈良; 李建生; 杨树高; 柴仲培; 徐荣楠

    2004-01-01

    Background Portasystemic shunts, especially total shunts, are effective tools for reducing portal pressure and controlling variceal bleeding but lead to high risk of encephalopathy and accelerating liver ailure. The purpose of this study is to evaluate the clinical effects of small-diameter expanded polytetrafluoroethylene (ePTFE) H-graft portacaval shunts in the treatment of portal hypertension. Methods Thirty-one patients with portal hypertension were treated with ePTFE small-diameter H-graft portacaval shunts from December 1995 to April 2002. Twenty-one had externally ringed grafts and 10 had non-ringed grafts; 20 had 10 mm diameter grafts and 11 had 8 mm grafts. The left gastric artery and coronary vein were ligated in 22 patients. Additionally, 6 patients underwent pericardial devascularization, and splenectomies were performed on 30 patients. Results An average decrease of free portal pressure (FPP) from (32.13 ~4.86) cmH2O before shunting to (12.55±5. 57) cmH2O after shunting was observed. Portal blood flow was reduced by 1/3 compared with the levels measured before shunting. Twenty-eight patients survived after the operation, and no upper gastrointestinal rebleeding occurred in the follow-up period (40.2 months on average). We lost contact with one patient. Color Doppler ultrasonography and/or portography revealed the shunts to be patent in 28 cases and occluded in 2 (6.4% ) cases. Encephalopathy developed in 4 patients (12.9%). Conclusion Small-diameter ePTFE H-graft portacaval shunts can effectively reduce portal pressure. Moreover, the majority of the hepatopetal flow from the portal vein can be adequately maintained. The reinforced shunts may achieve a higher rate of patency. Morbidity from encephalopathy was less frequent than in pateints receiving total shunts. Small-diameter H-graft portacaval shunts are also effective in preventing recurrent variceal bleeding.

  10. New empirical generalizations on the determinants of price elasticity

    NARCIS (Netherlands)

    Bijmolt, THA; Van Heerde, HJ; Pieters, RGM

    The importance of pricing decisions for firms has fueled an extensive stream of research on price elasticities. In an influential meta-analytical study, Tellis (1988) summarized price elasticity research findings until 1986. However, empirical generalizations on price elasticity require

  11. Noninvasive arterial blood pressure waveform monitoring using two- element ultrasound system.

    Science.gov (United States)

    Seo, Joohyun; Pietrangelo, Sabino J; Lee, Hae-Seung; Sodini, Charles G

    2015-04-01

    This work details noninvasive arterial blood pressure (ABP) waveform estimation based on an arterial vessel cross-sectional area measurement combined with an elasticity measurement of the vessel, represented by pulse wave velocity (PWV), using a two-element ultrasound system. The overall ABP waveform estimation is validated in a custom-designed experimental setup mimicking the heart and an arterial vessel segment with two single element transducers, assuming a constant hemodynamic system. The estimation of local PWV using the flow-area method produces unbiased elasticity estimation of the tube in a pressure waveform comparison. The measured PWV using 16 cardiac cycles of data is 8.47 + 0.63 m/s with an associated scaling error of -1.56 + 14.0% in a direct pressure waveform comparison, showing negligible bias error on average. The distension waveform obtained from a complex cross-correlation model estimator (C3M) reliably traces small pressure changes reflected by the diameter change. The excellent agreement of an estimated pressure waveform to the reference pressure waveform suggests the promising potential of a readily available, inexpensive, and portable ABP waveform monitoring device.

  12. Pulmonary artery pulsatility and effect on vessel diameter assessment in magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Shariat, Masoud, E-mail: masoudshariat@gmail.com [Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario (Canada); Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); Schantz, Daryl, E-mail: daryl.schantz@gmail.com [Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); Yoo, Shi-Joon, E-mail: shi-joon.yoo@sickkids.ca [Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); Wintersperger, Bernd J., E-mail: bernd.wintersperger@uhn.ca [Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario (Canada); Seed, Mike, E-mail: mike.seed@sickkids.ca [Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); Department of Cardiology, Hospital for Sick Children, Toronto, Ontario (Canada); Alnafisi, Bahiyah, E-mail: bahiyah.alnafisi@uhn.ca [Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario (Canada); Chu, Leysia, E-mail: leysia_99@yahoo.com [Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); MacGowan, Christopher K., E-mail: christopher.macgowan@sickkids.ca [Department of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Ontario (Canada); Amerom, Joshua van, E-mail: Joshu.vanamerom@sickkids.ca [Department of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Ontario (Canada); Grosse-Wortmann, Lars, E-mail: lars.grosse-wortmann@sickkids.ca [Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); Department of Cardiology, Hospital for Sick Children, Toronto, Ontario (Canada)

    2014-02-15

    Background: Information about thoracic vascular sizes can crucially affect clinical decision-making in cardiovascular disease. A variety of imaging techniques such as catheter angiography, contrast enhanced computed tomography (CT) and cardiac magnetic resonance imaging (CMR) are routinely used to measure vascular diameters. Traditionally, CMR black blood sequences were the main anatomical tool for visualization of vascular anatomy and still are in many centers. More recently, the vessel diameters are measured on multiplanar reconstructions derived from static magnetic resonance angiography (MRA). This study was performed to investigate the variation of vessel diameter measurements on different CMR techniques with respect to their data acquisition scheme. Methods: We recruited two groups of patients for this prospective study. One group included patients with repaired tetralogy of Fallot (TOF), with at least moderate pulmonary insufficiency and another group of patients who underwent CMR as part of a diagnostic work-up for arrhythmogenic right ventricular cardiomyopathy (ARVC). Additional images of the right pulmonary artery (RPA) were acquired in the double inversion recovery (DIR) black blood, cine steady state free precession (SSFP) and MRA. All images were reviewed by two CMR trained readers using the electronic caliper provided within the picture archiving and communication system package. The maximum diameter of each artery was recorded in millimeters with up to one decimal point. Paired t-tests and Bland–Altman plots were used for comparison of measurements between different sequences. Results: A total of 52 patients were recruited for this study, 26 patients in the TOF group (15 males, age 12.55 ± 2.9) and 26 patients in the ARVC group (15 males, age 15.6 ± 2.3). In both groups, the RPA sizes were not significantly different between the DIR images and diastolic cine SSFP (p > 0.05). Measurements on DIR were significantly smaller than those made on

  13. Expansion of endothelial surface by an increase of vessel diameter during tumor angiogenesis in experimental hepatocellular and pancreatic cancer

    Institute of Scientific and Technical Information of China (English)

    Eduard Ryschich; Eduard Schmidt; Sasa-Marcel Maksan; Ernst Klar; Jan Schmidt

    2004-01-01

    AIM: A low vessel density is a common feature of malignant tumors. We suggested that the expansion of vessel diameter might reconstitute the oxygen and nutritient's supply in this situation. The aim of the present study was to compare the number and diameter of blood vessels in pancreatic and liver carcinoma with normal tissue.METHODS: Tumor induction of pancreatic (DSL6A) or hepatocellular (Morris-hepatoma) carcinoma was performed in male Lewis (pancreatic cancer) and ACI (hepatoma) rats by an orthotopic inoculation of solid tumor fragments (pancreatic cancer) or tumor cells (hepatoma). Six weeks (pancreatic cancer) or 12 d (hepatoma) after tumor implantation, the tumor microvasculature as well as normal pancreatic or liver blood vessels were investigated by intravital microscopy. The number of perfused blood vessels in tumor and healthy tissue was assessed by computer-assisted image analysis.RESULTS: The vessel density in healthy pancreas (565±89n/mm2) was significantly higher compared to pancreatic cancer (116±36 n/mm2) (P<0.001). Healthy liver showed also a significantly higher vessel density (689±36 n/mm2) compared to liver carcinoma (286±32 n/mm2) (P<0.01). The comparison of diameter frequency showed a significant increase of vessel diameter in both malignant tumors compared to normal tissue (P<0.05).CONCLUSION: The expansion of endothelial cells during tumor angiogenesis is accompanied to a large extent by an increase of vessel diameter rather than by formation of new blood vessels. This may be a possible adaptive mechanism by which experimental pancreatic and hepatocellular cancers expand their endothelial diffusion surface of endothelium to compensate for inadequate neoangiogenesis.

  14. Elastic metamaterial beam with remotely tunable stiffness

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Wei [University of Michigan–Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240 (China); Yu, Zhengyue [School of Naval Architecture, Ocean & Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wang, Xiaole [School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Lai, Yun [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Yellen, Benjamin B., E-mail: yellen@duke.edu [University of Michigan–Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Mechanical Engineering and Materials Science, Duke University, P.O. Box 90300, Hudson Hall, Durham, North Carolina 27708 (United States)

    2016-02-07

    We demonstrate a dynamically tunable elastic metamaterial, which employs remote magnetic force to adjust its vibration absorption properties. The 1D metamaterial is constructed from a flat aluminum beam milled with a linear array of cylindrical holes. The beam is backed by a thin elastic membrane, on which thin disk-shaped permanent magnets are mounted. When excited by a shaker, the beam motion is tracked by a Laser Doppler Vibrometer, which conducts point by point scanning of the vibrating element. Elastic waves are unable to propagate through the beam when the driving frequency excites the first elastic bending mode in the unit cell. At these frequencies, the effective mass density of the unit cell becomes negative, which induces an exponentially decaying evanescent wave. Due to the non-linear elastic properties of the membrane, the effective stiffness of the unit cell can be tuned with an external magnetic force from nearby solenoids. Measurements of the linear and cubic static stiffness terms of the membrane are in excellent agreement with experimental measurements of the bandgap shift as a function of the applied force. In this implementation, bandgap shifts by as much as 40% can be achieved with ∼30 mN of applied magnetic force. This structure has potential for extension in 2D and 3D, providing a general approach for building dynamically tunable elastic metamaterials for applications in lensing and guiding elastic waves.

  15. Application of numerical methods to elasticity imaging.

    Science.gov (United States)

    Castaneda, Benjamin; Ormachea, Juvenal; Rodríguez, Paul; Parker, Kevin J

    2013-03-01

    Elasticity imaging can be understood as the intersection of the study of biomechanical properties, imaging sciences, and physics. It was mainly motivated by the fact that pathological tissue presents an increased stiffness when compared to surrounding normal tissue. In the last two decades, research on elasticity imaging has been an international and interdisciplinary pursuit aiming to map the viscoelastic properties of tissue in order to provide clinically useful information. As a result, several modalities of elasticity imaging, mostly based on ultrasound but also on magnetic resonance imaging and optical coherence tomography, have been proposed and applied to a number of clinical applications: cancer diagnosis (prostate, breast, liver), hepatic cirrhosis, renal disease, thyroiditis, arterial plaque evaluation, wall stiffness in arteries, evaluation of thrombosis in veins, and many others. In this context, numerical methods are applied to solve forward and inverse problems implicit in the algorithms in order to estimate viscoelastic linear and nonlinear parameters, especially for quantitative elasticity imaging modalities. In this work, an introduction to elasticity imaging modalities is presented. The working principle of qualitative modalities (sonoelasticity, strain elastography, acoustic radiation force impulse) and quantitative modalities (Crawling Waves Sonoelastography, Spatially Modulated Ultrasound Radiation Force (SMURF), Supersonic Imaging) will be explained. Subsequently, the areas in which numerical methods can be applied to elasticity imaging are highlighted and discussed. Finally, we present a detailed example of applying total variation and AM-FM techniques to the estimation of elasticity.

  16. Estimation of In vivo Cancellous Bone Elasticity

    Science.gov (United States)

    Otani, Takahiko; Mano, Isao; Tsujimoto, Toshiyuki; Yamamoto, Tadahito; Teshima, Ryota; Naka, Hiroshi

    2009-07-01

    The effect of decreasing bone density (a symptom of osteoporosis) is greater for cancellous bone than for dense cortical bone, because cancellous bone is metabolically more active. Therefore, the bone density or bone mineral density of cancellous bone is generally used to estimate the onset of osteoporosis. Elasticity or elastic constant is a fundamental mechanical parameter and is directly related to the mechanical strength of bone. Accordingly, elasticity is a preferable parameter for assessing fracture risk. A novel ultrasonic bone densitometer LD-100 has been developed to determine the mass density and elasticity of cancellous bone with a spatial resolution comparable to that of peripheral quantitative computed tomography. Bone density and bone elasticity are evaluated using ultrasonic parameters based on fast and slow waves in cancellous bone by modeling the ultrasonic wave propagation path. Elasticity is deduced from the measured bone density and the propagation speed of the fast wave. Thus, the elasticity of cancellous bone is approximately expressed by a cubic equation of bone density.

  17. Elastic metamaterial beam with remotely tunable stiffness

    Science.gov (United States)

    Qian, Wei; Yu, Zhengyue; Wang, Xiaole; Lai, Yun; Yellen, Benjamin B.

    2016-02-01

    We demonstrate a dynamically tunable elastic metamaterial, which employs remote magnetic force to adjust its vibration absorption properties. The 1D metamaterial is constructed from a flat aluminum beam milled with a linear array of cylindrical holes. The beam is backed by a thin elastic membrane, on which thin disk-shaped permanent magnets are mounted. When excited by a shaker, the beam motion is tracked by a Laser Doppler Vibrometer, which conducts point by point scanning of the vibrating element. Elastic waves are unable to propagate through the beam when the driving frequency excites the first elastic bending mode in the unit cell. At these frequencies, the effective mass density of the unit cell becomes negative, which induces an exponentially decaying evanescent wave. Due to the non-linear elastic properties of the membrane, the effective stiffness of the unit cell can be tuned with an external magnetic force from nearby solenoids. Measurements of the linear and cubic static stiffness terms of the membrane are in excellent agreement with experimental measurements of the bandgap shift as a function of the applied force. In this implementation, bandgap shifts by as much as 40% can be achieved with ˜30 mN of applied magnetic force. This structure has potential for extension in 2D and 3D, providing a general approach for building dynamically tunable elastic metamaterials for applications in lensing and guiding elastic waves.

  18. Failure Diameter of PBX 9502: Simulations with the SURFplus model

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-07-03

    SURFplus is a reactive burn model for high explosives aimed at modelling shock initiation and propagation of detonation waves. It utilizes the SURF model for the fast hot-spot reaction plus a slow reaction for the energy released by carbon clustering. A feature of the SURF model is that there is a partially decoupling between burn rate parameters and detonation wave properties. Previously, parameters for PBX 9502 that control shock ini- tiation had been calibrated to Pop plot data (distance-of-run to detonation as a function of shock pressure initiating the detonation). Here burn rate parameters for the high pres- sure regime are adjusted to t the failure diameter and the limiting detonation speed just above the failure diameter. Simulated results are shown for an uncon ned rate stick when the 9502 diameter is slightly above and slightly below the failure diameter. Just above the failure diameter, in the rest frame of the detonation wave, the front is sonic at the PBX/air interface. As a consequence, the lead shock in the neighborhood of the interface is supported by the detonation pressure in the interior of the explosive rather than the reaction immediately behind the front. In the interior, the sonic point occurs near the end of the fast hot-spot reaction. Consequently, the slow carbon clustering reaction can not a ect the failure diameter. Below the failure diameter, the radial extent of the detonation front decreases starting from the PBX/air interface. That is, the failure starts at the PBX boundary and propagates inward to the axis of the rate stick.

  19. Blood Transfusion

    Science.gov (United States)

    ... to their work or home. The availability of plastic bags that can have one or more satellite bags ... in preparing the donated blood. The use of plastic bags allows the blood center to make a variety ...

  20. Blood Disorders

    Science.gov (United States)

    ... risk for blood clots? Do You Know About Thalassemia? Language: English (US) Español (Spanish) Recommend on ... become hard, sticky, and shaped like a C. Thalassemia Red blood cell disorder that affects hemoglobin. Von ...

  1. Blood Clots

    Science.gov (United States)

    ... or prevent blood clots from dissolving properly. Risk factors for excessive blood clotting include Certain genetic disorders Atherosclerosis Diabetes Atrial fibrillation Overweight, obesity, and metabolic syndrome Some medicines Smoking deep vein ...

  2. Artifical Blood

    National Research Council Canada - National Science Library

    Goorha, Y K; Deb, Prabal; Chatterjee, T; Dhot, P S; Prasad, R S

    2003-01-01

    .... The problems and high cost factor involved in collecting and storing human blood and the pending world-wide shortages are the other driving forces contributing towards the development of blood substitutes...

  3. Artificial Blood

    National Research Council Canada - National Science Library

    Umit Yasar; Pinar Yilgor Huri; Nurten Dikmen

    2012-01-01

    The problems and additional cost factor involved in collecting and storing human blood, as well as the pending worldwide shortages are the main driving forces in the development of blood substitutes...

  4. Blood Vessel Tension Tester

    Science.gov (United States)

    1978-01-01

    In the photo, a medical researcher is using a specially designed laboratory apparatus for measuring blood vessel tension. It was designed by Langley Research Center as a service to researchers of Norfolk General Hospital and Eastern Virginia Medical School, Norfolk, Virginia. The investigators are studying how vascular smooth muscle-muscle in the walls of blood vessels-reacts to various stimulants, such as coffee, tea, alcohol or drugs. They sought help from Langley Research Center in devising a method of measuring the tension in blood vessel segments subjected to various stimuli. The task was complicated by the extremely small size of the specimens to be tested, blood vessel "loops" resembling small rubber bands, some only half a millimeter in diameter. Langley's Instrumentation Development Section responded with a miniaturized system whose key components are a "micropositioner" for stretching a length of blood vessel and a strain gage for measuring the smooth muscle tension developed. The micropositioner is a two-pronged holder. The loop of Mood vessel is hooked over the prongs and it is stretched by increasing the distance between the prongs in minute increments, fractions of a millimeter. At each increase, the tension developed is carefully measured. In some experiments, the holder and specimen are lowered into the test tubes shown, which contain a saline solution simulating body fluid; the effect of the compound on developed tension is then measured. The device has functioned well and the investigators say it has saved several months research time.

  5. SIMULATION OFTHERMO-ELASTICS PROPERTIESOFTHERMALBARRIERCOATINGS

    Directory of Open Access Journals (Sweden)

    A.M.Ferouani M. Ferouani

    2015-07-01

    Full Text Available Thermal barrier coatings are used to protect different parts in compressors and turbines from heat. They are generally composed of two layers, one metallic layer providing resistance to heat corrosion and oxidation, and one thermally insulating ceramic layer. Two different techniques are industrially used. Plasma spray results in a lamellar structure granting a low thermal conductivity, but with a low thermal expansion compliance. Electron Beam Physical Vapour Deposition generates a columnar structure allowing a better accommodation of the thermal expansion stresses, entailing improved lifetime of the coating, but with a higher thermal conductivity. The aim of the paper presented here is to develop a procedure of analysis based on the micro structural observation for the prediction of the properties of new coatings in court of industrial development and to predict the effect of the posterior thermal treatment on the properties of the coatings carried out. For a given coating, one has to calculate linear elasticity and its evolution with the temperature as well as thermal expansion, aiming at predicting different parameters related to the in service deterioration.  

  6. Capillary stretching of elastic fibers

    Science.gov (United States)

    Protiere, Suzie; Stone, Howard A.; Duprat, Camille

    2014-11-01

    Fibrous media consisting of constrained flexible fibers can be found in many engineered systems (membranes in filters, woven textile, matted paper). When such materials interact with a liquid, the presence of liquid/air interfaces induces capillary forces that deform the fibers. To model this interaction we study the behaviour of a finite volume of liquid deposited on two parallel flexible fibers clamped at both ends. A tension along the fibers is imposed and may be varied. We show that the system undergoes various morphological changes as the interfiber distance, the elasticity and the tension of the fibers are varied. For a certain range of parameters, the liquid spreads along the fibers and pulls them together, leading to the ``zipping'' of the fibers. This capillary adhesion can then be enhanced or reduced by changing the tension within the fibers. We will show that balancing stretching and capillary forces allows the prediction of this transition as well as the conditions for which detachment of the fibers occurs. These results may be used to prevent the clogging of fibrous membranes or to optimize the capture of liquids.

  7. Elastic/Inelastic Measurement Project

    Energy Technology Data Exchange (ETDEWEB)

    Yates, Steven [Univ. of Kentucky, Lexington, KY (United States); Hicks, Sally [Univ. of Dallas, TX (United States); Vanhoy, Jeffrey [U.S. Naval Academy, Annapolis, MD (United States); McEllistrem, Marcus [Univ. of Kentucky, Lexington, KY (United States)

    2016-03-01

    The work scope involves the measurement of neutron scattering from natural sodium (23Na) and two isotopes of iron, 56Fe and 54Fe. Angular distributions, i.e., differential cross sections, of the scattered neutrons will be measured for 5 to 10 incident neutron energies per year. The work of the first year concentrates on 23Na, while the enriched iron samples are procured. Differential neutron scattering cross sections provide information to guide nuclear reaction model calculations in the low-­energy (few MeV) fast-­neutron region. This region lies just above the isolated resonance region, which in general is well studied; however, model calculations are difficult in this region because overlapping resonance structure is evident and direct nuclear reactions are becoming important. The standard optical model treatment exhibits good predictive ability for the wide-­region average cross sections but cannot treat the overlapping resonance features. In addition, models that do predict the direct reaction component must be guided by measurements to describe correctly the strength of the direct component, e.g., β2 must be known to describe the direct component of the scattering to the first excited state. Measurements of the elastic scattering differential cross sections guide the optical model calculations, while inelastic differential cross sections provide the crucial information for correctly describing the direct component. Activities occurring during the performance period are described.

  8. Reversible Simulations of Elastic Collisions

    CERN Document Server

    Perumalla, Kalyan S

    2013-01-01

    Consider a system of N identical hard spherical particles moving in a d-dimensional box and undergoing elastic, possibly multi-particle, collisions. We develop a new algorithm that recovers the pre-collision state from the post-collision state of the system, across a series of consecutive collisions, with essentially no memory overhead. The challenge in achieving reversibility for an n-particle collision (where, n << N) arises from the presence of nd-d-1 degrees of freedom during each collision, and from the complex geometrical constraints placed on the colliding particles. To reverse the collisions in a traditional simulation setting, all of the particular realizations of these degrees of freedom during the forward simulation must be saved. This limitation is addressed here by first performing a pseudo-randomization of angles, ensuring determinism in the reverse path for any values of n and d. To address the more difficult problem of geometrical and dynamic constraints, a new approach is developed whic...

  9. Blood Conservation.

    Science.gov (United States)

    Martin, Jeremiah T; Ferraris, Victor A

    2015-01-01

    Patient blood management requires multi-modality and multidisciplinary collaboration to identify patients who are at increased risk of requiring blood transfusion and therefore decrease exposure to blood products. Transfusion is associated with poor postoperative outcomes, and guidelines exist to minimize transfusion requirements. This review highlights recent studies and efforts to apply patient blood management across disease processes and health care systems. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Marangoni elasticity of flowing soap films

    CERN Document Server

    Kim, Ildoo

    2016-01-01

    We measure the Marangoni elasticity of a flowing soap film to be 22 dyne/cm irrespective of its width, thickness, flow speed, or the bulk soap concentration. We perform this measurement by generating an oblique shock in the soap film and measuring the shock angle, flow speed and thickness. We postulate that the elasticity is constant because the film surface is crowded with soap molecules. Our method allows non-destructive measurement of flowing soap film elasticity, and the value 22 dyne/cm is likely applicable to other similarly constructed flowing soap films.

  11. Marangoni elasticity of flowing soap films

    OpenAIRE

    Kim, Ildoo; Mandre, Shreyas

    2016-01-01

    We measure the Marangoni elasticity of a flowing soap film to be 22 dyne/cm irrespective of its width, thickness, flow speed, or the bulk soap concentration. We perform this measurement by generating an oblique shock in the soap film and measuring the shock angle, flow speed and thickness. We postulate that the elasticity is constant because the film surface is crowded with soap molecules. Our method allows non-destructive measurement of flowing soap film elasticity, and the value 22 dyne/cm ...

  12. DAEs and PDEs in elastic multibody systems

    Science.gov (United States)

    Simeon, B.

    1998-12-01

    Elastic multibody systems arise in the simulation of vehicles, robots, air- and spacecrafts. They feature a mixed structure with differential-algebraic equations (DAEs) governing the gross motion and partial differential equations (PDEs) describing the elastic deformation of particular bodies. We introduce a general modelling framework for this new application field and discuss numerical simulation techniques from several points of view. Due to different time scales, singular perturbation theory and model reduction play an important role. A slider crank mechanism with a 2D FE grid for the elastic connecting rod illustrates the techniques.

  13. Elasticity of Substitution and Antidumping Measures

    DEFF Research Database (Denmark)

    Drud Hansen, Jørgen; Meinen, Philipp; Nielsen, Jørgen Ulff-Møller

    Abstract This paper analyzes the role of the elasticity of substitution for anti-dumping decisions across countries. In monopolistic competition models with cost heterogeneous firms across countries, price differences vary inversely with the elasticity of substitution. Anti-dumping duties should...... therefore also vary inversely with the elasticity of substitution at least for countries which have a strong focus on prices in the determination of their anti-dumping measures. We test this for ten countries from 1990 to 2009 using data on anti-dumping from Chad Bown (2010) and US-data at 8-digit level...

  14. Full Elasticity Tensor from Thermal Diffuse Scattering

    Science.gov (United States)

    Wehinger, Björn; Mirone, Alessandro; Krisch, Michael; Bosak, Alexeï

    2017-01-01

    We present a method for the precise determination of the full elasticity tensor from a single crystal diffraction experiment using monochromatic x rays. For the two benchmark systems calcite and magnesium oxide, we show that the measurement of thermal diffuse scattering in the proximity of Bragg reflections provides accurate values of the complete set of elastic constants. This approach allows for a reliable and model-free determination of the elastic properties and can be performed together with crystal structure investigation in the same experiment.

  15. Love Wave Propagation in Poro elasticity

    Directory of Open Access Journals (Sweden)

    Y.V. Rama Rao

    1978-10-01

    Full Text Available It is observed that on similar reasons as in classical theory of elasticity, SH wave propagation in a semi infinite poroelastic body is not possible and is possible when there is a layer of another poro elastic medium over it i.e., Love waves. Two particular cases are considered in one of which phase velocity can be determined for a given wave length. In the same case, equation for phase velocity is of the same form as that of the classical theory of Elasticity.

  16. Hole diameters in pet bottles used for fruit fly capture

    Directory of Open Access Journals (Sweden)

    Maurico Paulo Batistella Pasini

    2015-05-01

    Full Text Available Two experiments were conducted during the period from 31 January to 6 March 2012 in Santa Maria, Rio Grande do Sul State, Brazil to determine the efficiency of different hole diameters in PET trap bottles on pests in guava and persimmon orchards. In a randomised block design in a factorial scheme, we assessed the average number adults of Anastrepha fraterculus, Ceratitis capitata (Diptera: Tephitidae and Zaprionus indianus (Diptera: Drosophilidae infruits thatemerged in two situations (in the plant and on the soil; we also assessed the number of captured adults in trap bottlesunder two conditions, different hole diameters and different days after placement of the attractive solution. Smaller diameter sizescaptured more A. fraterculus, C. capitata and Z. indianusadults. The 1.0 cm diameter was the most efficient hole size in reducing the adult emergence of Tephritidae to Z. indianus, whereas the smallest diameter hole sizes, 0.6 and 0.8 cm, showed the highest efficiencies in controlling adult emergence in persimmon fruit and guava fruit.

  17. Parametric Probability Distribution Functions for Axon Diameters of Corpus Callosum

    Directory of Open Access Journals (Sweden)

    Farshid eSepehrband

    2016-05-01

    Full Text Available Axon diameter is an important neuroanatomical characteristic of the nervous system that alters in the course of neurological disorders such as multiple sclerosis. Axon diameters vary, even within a fiber bundle, and are not normally distributed. An accurate distribution function is therefore beneficial, either to describe axon diameters that are obtained from a direct measurement technique (e.g., microscopy, or to infer them indirectly (e.g., using diffusion-weighted MRI. The gamma distribution is a common choice for this purpose (particularly for the inferential approach because it resembles the distribution profile of measured axon diameters which has been consistently shown to be non-negative and right-skewed. In this study we compared a wide range of parametric probability distribution functions against empirical data obtained from electron microscopy images. We observed that the gamma distribution fails to accurately describe the main characteristics of the axon diameter distribution, such as location and scale of the mode and the profile of distribution tails. We also found that the generalized extreme value distribution consistently fitted the measured distribution better than other distribution functions. This suggests that there may be distinct subpopulations of axons in the corpus callosum, each with their own distribution profiles. In addition, we observed that several other distributions outperformed the gamma distribution, yet had the same number of unknown parameters; these were the inverse Gaussian, log normal, log logistic and Birnbaum-Saunders distributions.

  18. Effect of rootstock diameter on apple saplings growth

    Directory of Open Access Journals (Sweden)

    VAHID AVDIU

    2014-03-01

    Full Text Available This research paper presents the results of a field trial with managed nursery trees including two apple cultivars Golden Reinders and Gala Galaxy on the rootstocks M9 and MM 106. In April 2011, the saplings (bench grafted in March 2011 were planted in the distance 100 cm x 35 cm in randomized block design in threecombinations of rootstock diameters (5-7 mm, 7-9 mm, 9-11 mm with threereplications (in total 60 saplings for each apple cultivar-rootstock and combinations in Mirovica, Kosovo. The following parameters were examined: growth, rootstock diameter, scion diameter, and stocks growth dynamic. The experimental design was a ANOVAs one-way analysing two different factors cultivars, rootstocks types and treatments (three combinations of rootstocks diameter. Significant differences were found in scion thickness and sapling growth among the three different combinations of rootstock diameter, dimensions and cultivars. Insignificant were differences were found within factors as cultivar, rootstock and their combinations Key words: Amino acids, Moringa oleifera, poultry manure.

  19. Magnetoimpedance of Electroplated Wires with Large Core Diameters

    Institute of Scientific and Technical Information of China (English)

    C. Sirisathitkul; P. Jantaratana

    2009-01-01

    Monolayered Co and trilayered Co/Cu/Co were electroplated on 485 Μm-diameter Cu wires using the bath pH 2.5. These wires can be functioned as magnetic sensors owing to their magnetoimpedance (Ml) effect. By measuring at four different frequencies (100, 250, 500, and 1000 kHz) and Co thicknesses (2.5, 5.0, 10.0, and 25.0Μm), the Ml ratio of electroplated Co on Cu wires tended to increase with increasing Co thickness and frequency of the driving current. The Co/Cu/Co on Cu wires exhibited even higher Ml ratio. The magnetic layer also regulated the magnetic inductions and anisotropy regardless of the size of nonmagnetic core. Nevertheless, the diameter of the Cu core had a significant effect on the Ml ratio. By comparing with the 47.7 μm-diameter Ag cores electroplated by Co and Co/Cu/Co of the same thickness, the Cu cores with a larger diameter gave rise to a larger Ml ratio because their lower electrical resistance enhanced the crossing effect. Substantial Ml ratio was observed even in a low frequency regime because the skin effect occurred at a low frequency in the case of electroplated wires with large core diameters.

  20. Memory, emotion, and pupil diameter: Repetition of natural scenes.

    Science.gov (United States)

    Bradley, Margaret M; Lang, Peter J

    2015-09-01

    Recent studies have suggested that pupil diameter, like the "old-new" ERP, may be a measure of memory. Because the amplitude of the old-new ERP is enhanced for items encoded in the context of repetitions that are distributed (spaced), compared to massed (contiguous), we investigated whether pupil diameter is similarly sensitive to repetition. Emotional and neutral pictures of natural scenes were viewed once or repeated with massed (contiguous) or distributed (spaced) repetition during incidental free viewing and then tested on an explicit recognition test. Although an old-new difference in pupil diameter was found during successful recognition, pupil diameter was not enhanced for distributed, compared to massed, repetitions during either recognition or initial free viewing. Moreover, whereas a significant old-new difference was found for erotic scenes that had been seen only once during encoding, this difference was absent when erotic scenes were repeated. Taken together, the data suggest that pupil diameter is not a straightforward index of prior occurrence for natural scenes. © 2015 Society for Psychophysiological Research.

  1. Thoracic and abdominal aortic diameters in a general population: MRI-based reference values and association with age and cardiovascular risk factors

    Energy Technology Data Exchange (ETDEWEB)

    Mensel, Birger; Hesselbarth, Lydia; Wenzel, Michael; Kuehn, Jens-Peter; Hegenscheid, Katrin [University Medicine Greifswald, Institute of Diagnostic Radiology and Neuroradiology, Greifswald (Germany); Doerr, Marcus [University Medicine Greifswald, Department of Internal Medicine, Greifswald (Germany); DZHK (German Center for Cardiovascular Research), partner site Greifswald, Greifswald (Germany); Voelzke, Henry [University Medicine Greifswald, Institute for Community Medicine, Greifswald (Germany); DZHK (German Center for Cardiovascular Research), partner site Greifswald, Greifswald (Germany); Lieb, Wolfgang [Christian Albrechts University, Institute of Epidemiology, Kiel (Germany); Lorbeer, Roberto [Ludwig-Maximilians-University Hospital, Institute of Clinical Radiology, Munich (Germany)

    2016-04-15

    To generate reference values for thoracic and abdominal aortic diameters determined by magnetic resonance imaging (MRI) and analyse their association with cardiovascular risk factors in the general population. Data from participants (n = 1759) of the Study of Health in Pomerania were used for analysis in this study. MRI measurement of thoracic and abdominal aortic diameters was performed. Parameters for calculation of reference values according to age and sex analysis were provided. Multivariable linear regression models were used for determination of aortic diameter-related risk factors, including smoking, blood pressure (BP), high-density lipoprotein cholesterol (HDL-C). For the ascending aorta (β = -0.049, p < 0.001), the aortic arch (β = -0.061, p < 0.001) and the subphrenic aorta (β = -0.018, p = 0.004), the body surface area (BSA)-adjusted diameters were lower in men. Multivariable-adjusted models revealed significant increases in BSA-adjusted diameters with age for all six aortic segments (p < 0.001). Consistent results for all segments were observed for the positive associations of diastolic BP (β = 0.001; 0.004) and HDL (β = 0.035; 0.087) with BSA-adjusted aortic diameters and for an inverse association of systolic BP (β = -0.001). Some BSA-adjusted median aortic diameters are smaller in men than in women. All diameters increase with age, diastolic blood pressure and HDL-C and decrease as systolic BP increases. (orig.)

  2. Multiscale modeling of blood flow: from single cells to blood rheology.

    Science.gov (United States)

    Fedosov, Dmitry A; Noguchi, Hiroshi; Gompper, Gerhard

    2014-04-01

    Mesoscale simulations of blood flow, where the red blood cells are described as deformable closed shells with a membrane characterized by bending rigidity and stretching elasticity, have made much progress in recent years to predict the flow behavior of blood cells and other components in various flows. To numerically investigate blood flow and blood-related processes in complex geometries, a highly efficient simulation technique for the plasma and solutes is essential. In this review, we focus on the behavior of single and several cells in shear and microcapillary flows, the shear-thinning behavior of blood and its relation to the blood cell structure and interactions, margination of white blood cells and platelets, and modeling hematologic diseases and disorders. Comparisons of the simulation predictions with existing experimental results are made whenever possible, and generally very satisfactory agreement is obtained.

  3. On sub-determinants and the diameter of polyhedra

    CERN Document Server

    Bonifas, Nicolas; Eisenbrand, Friedrich; Hähnle, Nicolai; Niemeier, Martin

    2011-01-01

    We derive a new upper bound on the diameter of a polyhedron P = {x \\in R^n : Ax <= b}, where A \\in Z^{m\\timesn}. The bound is polynomial in n and the largest absolute value of a sub-determinant of A, denoted by \\Delta. More precisely, we show that the diameter of P is bounded by O(\\Delta^2 n^4 log n\\Delta). If P is bounded, then we show that the diameter of P is at most O(\\Delta^2 n^3.5 log n\\Delta). For the special case in which A is a totally unimodular matrix, the bounds are O(n^4 log n) and O(n^3.5 log n) respectively. This improves over the previous best bound of O(m^16 n^3 (log mn)^3) due to Dyer and Frieze.

  4. Axon diameter mapping in crossing fibers with diffusion MRI

    DEFF Research Database (Denmark)

    Zhang, Hui; Dyrby, Tim B; Alexander, Daniel C

    2011-01-01

    tissue than measures derived from diffusion tensor imaging. Most existing techniques for axon diameter mapping assume a single axon orientation in the tissue model, which limits their application to only the most coherently oriented brain white matter, such as the corpus callosum, where the single...... orientation assumption is a reasonable one. However, fiber crossings and other complex configurations are widespread in the brain. In such areas, the existing techniques will fail to provide useful axon diameter indices for any of the individual fiber populations. We propose a novel crossing fiber tissue...... of the technique by establishing reasonable axon diameter indices in the crossing region at the interface of the cingulum and the corpus callosum....

  5. The angular diameter and distance of the Cepheid Zeta Geminorum

    CERN Document Server

    Kervella, P; Perrin, G; Schöller, M; Traub, W A; Lacasse, M D

    2001-01-01

    Cepheids are the primary distance indicators for extragalactic astronomy and therefore are of very high astrophysical interest. Unfortunately, they are rare stars, situated very far from Earth.Though they are supergiants, their typical angular diameter is only a few milliarcseconds, making them very challenging targets even for long-baseline interferometers. We report observations that were obtained in the K prime band (2-2.3 microns), on the Cepheid Zeta Geminorum with the FLUOR beam combiner, installed at the IOTA interferometer. The mean uniform disk angular diameter was measured to be 1.64 +0.14 -0.16 mas. Pulsational variations are not detected at a significant statistical level, but future observations with longer baselines should allow a much better estimation of their amplitude. The distance to Zeta Gem is evaluated using Baade-Wesselink diameter determinations, giving a distance of 502 +/- 88 pc.

  6. Improved Design Basis for Laterally Loaded Large Diameter Pile

    DEFF Research Database (Denmark)

    Leth, Caspar Thrane

    . The expected development of offshore wind farms is towards larger farms, larger turbines and larger water depths. Monopiles have been applied widely and it is of interest to investigate the possibilities to further optimize the design and in particular the modelling of the soil-structure interaction...... on the structure and the productivity of the turbine. Current design practice for monopiles are based on p-y curves developed for slender piles with a diameter of 0.6 m. The focus on the structure stiffness has entailed a significant research on the soil-structure interaction for large diameter monopiles...... in dry sand by use of centrifuge modelling and to compare the findings with the standard p-y curves. It has been chosen to apply piles with an embedment length of 6 to 10 times the diameter of the applied piles. The general static behaviour of monopiles in dry sand has based on centrifuge tests been...

  7. Reduced arterial diameter during static exercise in humans

    DEFF Research Database (Denmark)

    Olesen, H L; Mitchell, J H; Friedman, D B

    1995-01-01

    of another limb. Static exercise increased heart rate and mean arterial pressure, which were largest during one-leg knee extension. After exercise heart rate and mean arterial pressure returned to the resting level. No changes were recorded in arterial carbon dioxide tension, and the rate of perceived......In eight subjects luminal diameter of the resting limb radial and dorsalis pedis arteries was determined by high-resolution ultrasound (20 MHz). This measurement was followed during rest and during 2 min of static handgrip or of one-leg knee extension at 30% of maximal voluntary contraction...... exertion was approximately 15 units after both types of exercise. The dorsalis pedis arterial diameter was 1.50 +/- 0.20 mm (mean and SE) and the radial AD 2.45 +/- 0.12 mm. During both types of contractions the luminal diameters decreased approximately 3.5% within the first 30 s (P

  8. Directional Solidification and Convection in Small Diameter Crucibles

    Science.gov (United States)

    Chen, J.; Sung, P. K.; Tewari, S. N.; Poirier, D. R.; DeGroh, H. C., III

    2003-01-01

    Pb-2.2 wt% Sb alloy was directionally solidified in 1, 2, 3 and 7 mm diameter crucibles. Pb-Sb alloy presents a solutally unstable case. Under plane-front conditions, the resulting macrosegregation along the solidified length indicates that convection persists even in the 1 mm diameter crucible. Al-2 wt% Cu alloy was directionally solidified because this alloy was expected to be stable with respect to convection. Nevertheless, the resulting macrosegregation pattern and the microstructure in solidified examples indicated the presence of convection. Simulations performed for both alloys show that convection persists for crucibles as small as 0.6 mm of diameter. For the solutally stable alloy, Al-2 wt% Cu, the simulations indicate that the convection arises from a lateral temperature gradient.

  9. Improved Design Basis for Laterally Loaded Large Diameter Pile

    DEFF Research Database (Denmark)

    Leth, Caspar Thrane

    in dry sand by use of centrifuge modelling and to compare the findings with the standard p-y curves. It has been chosen to apply piles with an embedment length of 6 to 10 times the diameter of the applied piles. The general static behaviour of monopiles in dry sand has based on centrifuge tests been...... in sand by use of physical modelling and comparison of the findings with standard p-y curves. The present research is based on use of the centrifuge facilities at Danish Technical University (DTU), the sole geotechnical centrifuge in Scandinavia. It became evident in the initial phase of the research...... that the available centrifuge facilities at DTU was outdated and the focus was changed to establish up-to-date centrifuge facilities for medium to large diameter piles, and to initiate the research on the behaviour of large diameter piles in sand under static and cyclic loading. Key elements in the establishment...

  10. Application of direct tracking method for measuring electrospun nanofiber diameter

    Directory of Open Access Journals (Sweden)

    M. Ziabari

    2009-03-01

    Full Text Available In this paper, direct tracking method as an image analysis based technique for measuring electrospun nanofiber diameter has been presented and compared with distance transform method. Samples with known characteristics generated using a simulation scheme known as µ-randomness were employed to evaluate the accuracy of the method. Electrospun webs of polyvinyl alcohol (PVA were also used to verify the applicability of the method on real samples. Since direct tracking as well as distance transform require binary input images, micrographs of the electrospun webs obtained from Scanning Electron Microscopy (SEM were first converted to black and white using local thresholding. Direct tracking resulted in more accurate estimations of fiber diameter for simulated images as well as electrospun webs suggesting the usefulness of the method for electrospun nanofiber diameter measurement.

  11. NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos

    CERN Document Server

    Nugent, C R; Bauer, J; Cutri, R M; Kramer, E A; Grav, T; Masiero, J; Sonnett, S; Wright, E L

    2016-01-01

    The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids and 8,885 other asteroids. $84\\%$ of the near-Earth asteroids did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within $ \\pm \\sim20\\%$ and $\\pm\\sim40\\%$, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large ($>100$ m), and have low albedos.

  12. Middle cerebral artery diameter changes during rhythmic handgrip exercise in humans.

    Science.gov (United States)

    Verbree, J; Bronzwaer, Agt; van Buchem, M A; Daemen, Mjap; van Lieshout, J J; van Osch, Mjp

    2017-08-01

    Transcranial Doppler (TCD) sonography is a frequently employed technique for quantifying cerebral blood flow by assuming a constant arterial diameter. Given that exercise increases arterial pressure by sympathetic activation, we hypothesized that exercise might induce a change in the diameter of large cerebral arteries. Middle cerebral artery (MCA) cross-sectional area was assessed in response to handgrip exercise by direct magnetic resonance imaging (MRI) observations. Twenty healthy subjects (11 female) performed three 5 min bouts of rhythmic handgrip exercise at 60% maximum voluntary contraction, alternated with 5 min of rest. High-resolution 7 T MRI scans were acquired perpendicular to the MCA. Two blinded observers manually determined the MCA cross-sectional area. Sufficient image quality was obtained in 101 MCA-scans of 19 subjects (age-range 20-59 years). Mixed effects modelling showed that the MCA cross-sectional area decreased by 2.1 ± 0.8% (p = 0.01) during handgrip, while the heart rate increased by 11 ± 2% (p exercise. This further strengthens the current concept of sympathetic control of large cerebral arteries, showing in vivo vasoconstriction during exercise-induced sympathetic activation. Moreover, care must be taken when interpreting TCD exercise studies as diameter constancy cannot be assumed.

  13. Biomechanical investigation of titanium elastic nail prebending for treating diaphyseal long bone fractures.

    Science.gov (United States)

    Chen, Yen-Nien; Lee, Pei-Yuan; Chang, Chih-Wei; Ho, Yi-Hung; Peng, Yao-Te; Chang, Chih-Han; Li, Chun-Ting

    2016-12-02

    This study numerically investigated the deformation of titanium elastic nails prebent at various degrees during implantation into the intramedullary canal of fractured bones and the mechanism by which this prebending influenced the stability of the fractured bone. Three degrees of prebending the implanted portions of the nails were used: equal to, two times, and three times the diameter of the intramedullary canal. Furthermore, a simulated diaphyseal fracture with a 5-mm gap was created in the middle shaft portion of the bone fixed with two elastic nails in a double C-type configuration. End caps were simulated using a constraint equation. To confirm that the simulation process is able to present the mechanical response of the nail inside the intramedullary, an experiment was conducted by using sawbone for validation. The results indicated that increasing the degrees of nail prebending facilitated straightening the nails against the inner aspect of canal after implantation, with increase in stability under torsion. Furthermore, reducing nail prebending caused a larger portion of the nails to move closer to the loading site and center of bone after implantation; the use of end caps prevented the nail tips from collapsing and increased axial stability. End cap use was critical for preventing the nail tips from collapsing and for increasing the stability of the nails prebent at a degree equal to the diameter of the canal with insufficient frictional force between the nail and canal. Therefore, titanium elastic nail prebending in a double C-type configuration with a degree three times the diameter of the canal represents a superior solution for treating transverse fractures without a gap, whereas that with a degree equal to the diameter of the intramedullary canal and combined with end cap use represents an advanced solution for treating comminuted fractures in a diaphyseal long bone fracture.

  14. Mechanics of finite cracks in dissimilar anisotropic elastic media considering interfacial elasticity

    Science.gov (United States)

    Juan, Pierre-Alexandre; Dingreville, Rémi

    2017-02-01

    Interfacial crack fields and singularities in bimaterial interfaces (i.e., grain boundaries or dissimilar materials interfaces) are considered through a general formulation for two-dimensional (2-D) anisotropic elasticity while accounting for the interfacial structure by means of an interfacial elasticity paradigm. The interfacial elasticity formulation introduces boundary conditions that are effectively equivalent to those for a weakly bounded interface. This formalism considers the 2-D crack-tip elastic fields using complex variable techniques. While the consideration of the interfacial elasticity does not affect the order of the singularity, it modifies the oscillatory effects associated with problems involving interface cracks. Constructive or destructive "interferences" are directly affected by the interface structure and its elastic response. This general formulation provides an insight on the physical significance and the obvious coupling between the interface structure and the associated mechanical fields in the vicinity of the crack tip.

  15. ELASTIC CHARACTERIZATION OF Eucalyptus citriodora WOOD

    Directory of Open Access Journals (Sweden)

    Adriano Wagner Ballarin

    2003-01-01

    Full Text Available This paper contributed to the elastic characterization of Eucalyptus citriodora grown inBrazil, considering an orthotropic model and evaluating its most important elastic constants.Considering this as a reference work to establish basic elastic ratios — several important elasticconstants of Brazilian woods were not determined yet - the experimental set-up utilized one tree of 65years old from plantations of “Horto Florestal Navarro de Andrade”, at Rio Claro-SP, Brazil. All theexperimental procedures attended NBR 7190/97 – Brazilian Code for wooden structures –withconventional tension and compression tests. Results showed statistical identity between compressionand tension modulus of elasticity. The relation observed between longitudinal and radial modulus ofelasticity was 10 (EL/ER ≈ 10 and same relation, considering shear modulus (modulus of rigidity was20 (EL/GLR ≈ 20. These results, associated with Poisson’s ratios herein determined, allow theoreticalmodeling of wood mechanical behavior in structures.

  16. Theories for Elastic Plates via Orthogonal Polynomials

    DEFF Research Database (Denmark)

    Krenk, Steen

    1981-01-01

    A complementary energy functional is used to derive an infinite system of two-dimensional differential equations and appropriate boundary conditions for stresses and displacements in homogeneous anisotropic elastic plates. Stress boundary conditions are imposed on the faces a priori...

  17. Measuring Moduli Of Elasticity At High Temperatures

    Science.gov (United States)

    Wolfenden, Alan

    1993-01-01

    Shorter, squatter specimens and higher frequencies used in ultrasonic measurement technique. Improved version of piezo-electric ultrasonic composite oscillator technique used to measure moduli of elasticity of solid materials at high temperatures.

  18. Equivalent boundary integral equations for plane elasticity

    Institute of Scientific and Technical Information of China (English)

    胡海昌; 丁皓江; 何文军

    1997-01-01

    Indirect and direct boundary integral equations equivalent to the original boundary value problem of differential equation of plane elasticity are established rigorously. The unnecessity or deficiency of some customary boundary integral equations is indicated by examples and numerical comparison.

  19. Dynamic response of visco-elastic plates

    Science.gov (United States)

    Kadıoǧlu, Fethi; Tekin, Gülçin

    2016-12-01

    In this study, a comprehensive analysis about the dynamic response characteristics of visco-elastic plates is given. To construct the functional in the Laplace-Carson domain for the analysis of visco-elastic plates based on the Kirchhoff hypothesis, functional analysis method is employed. By using this new energy functional in the Laplace-Carson domain, moment values that are important for engineers can be obtained directly with excellent accuracy and element equations can be written explicitly. Three-element model is considered for modelling the visco-elastic material behavior. The solutions obtained in the Laplace-Carson domain by utilizing mixed finite element formulation are transformed to the time domain using the Durbin's inverse Laplace transform technique. The proposed mixed finite element formulation is shown to be simple to implement and gives satisfactory results for dynamic response of visco-elastic plates.

  20. Extremal Overall Elastic Response of Polycrystalline Materials

    DEFF Research Database (Denmark)

    Bendsøe, Martin P; Lipton, Robert

    1996-01-01

    Polycrystalline materials comprised of grains obtained froma single anisotropic material are considered in the frameworkof linear elasticity. No assumptions on the symmetry of thepolycrystal are made. We subject the material to independentexternal strain and stress fields with prescribed mean...

  1. Characterizing the elasticity of hollow metal nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ji Changjiang; Park, Harold S [Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN 37235 (United States)

    2007-03-21

    We have performed atomistic simulations on solid and hollow copper nanowires to quantify the elastic properties of hollow nanowires (nanoboxes). We analyse variations in the modulus, yield stress and strain for <100> and <110> nanoboxes by varying the amount of bulk material that is removed to create the nanoboxes. We find that, while <100> nanoboxes show no improvement in elastic properties as compared to solid <100>nanowires, <110> nanoboxes can show enhanced elastic properties as compared to solid <110> nanowires. The simulations reveal that the elastic properties of the nanoboxes are strongly dependent on the relative strength of the bulk material that has been removed, as well as the total surface area of the nanoboxes, and indicate the potential of ultralight, high-strength nanomaterials such as nanoboxes.

  2. Optical coating uniformity of 200mm (8") diameter precut wafers

    Science.gov (United States)

    Burt, Travis C.; Fisher, Mark; Brown, Dean; Troiani, David

    2017-02-01

    Automated spectroscopic profiling (mapping) of a 200 mm diameter near infrared high reflector (centered at 1064 nm) are presented. Spatial resolution at 5 mm or less was achieved using a 5 mm × 1.5 mm monochromatic beam. Reflection changes of 1.0% across the wafer diameter were observed under s-polarized and p- polarized conditions. Redundancy was established for each chord by re-measuring the center of the wafer and reproducibility of approximately platform for angles of incidence in the range 5°stream processing.

  3. On the diameter of the Kronecker product graph

    CERN Document Server

    Hu, Fu-Tao

    2012-01-01

    Let $G_1$ and $G_2$ be two undirected nontrivial graphs. The Kronecker product of $G_1$ and $G_2$ denoted by $G_1\\otimes G_2$ with vertex set $V(G_1)\\times V(G_2)$, two vertices $x_1x_2$ and $y_1y_2$ are adjacent if and only if $(x_1,y_1)\\in E(G_1)$ and $(x_2,y_2)\\in E(G_2)$. This paper presents a formula for computing the diameter of $G_1\\otimes G_2$ by means of the diameters and primitive exponents of factor graphs.

  4. NEOWISE REACTIVATION MISSION YEAR ONE: PRELIMINARY ASTEROID DIAMETERS AND ALBEDOS

    Energy Technology Data Exchange (ETDEWEB)

    Nugent, C. R.; Cutri, R. M. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Mainzer, A.; Masiero, J.; Bauer, J.; Kramer, E.; Sonnett, S.; Stevenson, R. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Grav, T. [Planetary Science Institute, Tucson, AZ (United States); Wright, E. L., E-mail: cnugent@ipac.caltech.edu [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

    2015-12-01

    We present preliminary diameters and albedos for 7956 asteroids detected in the first year of the NEOWISE Reactivation mission. Of those, 201 are near-Earth asteroids and 7755 are Main Belt or Mars-crossing asteroids. 17% of these objects have not been previously characterized using the Near-Earth Object Wide-field Infrared Survey Explorer, or “NEOWISE” thermal measurements. Diameters are determined to an accuracy of ∼20% or better. If good-quality H magnitudes are available, albedos can be determined to within ∼40% or better.

  5. Blood Facts and Statistics

    Science.gov (United States)

    ... Facts and Statistics Printable Version Blood Facts and Statistics Facts about blood needs Facts about the blood ... to Top Learn About Blood Blood Facts and Statistics Blood Components Whole Blood and Red Blood Cells ...

  6. Hyaluronic acid enhancement of expanded polytetrafluoroethylene for small diameter vascular grafts

    Science.gov (United States)

    Lewis, Nicole R.

    Cardiovascular disease is the leading cause of mortality and morbidity in the United States and other developed countries. In the United States alone, 8 million people are diagnosed with peripheral arterial disease per year and over 250,000 patients have coronary bypass surgery each year. Autologous blood vessels are the standard graft used in small diameter (hyaluronic acid (HA), evaluate thrombogenic potential of ePTFE-HA grafts, and evaluate graft mechanical properties and coating durability. The results in this work indicate the successful production of ePTFE-HA materials using a solvent infiltration technique. Surface interactions with blood show increased platelet adhesion on HA-modified surfaces, though evidence may suggest less platelet activation and erythrocyte lysis. Significant changes in mechanical properties of HA-modified ePTFE materials were observed. Further investigation into solvent selection, uniformity of HA, endothelialization, and dynamic flow testing would be beneficial in the evaluation of these materials for use in small diameter vascular graft bypass procedures.

  7. Electrospinning thermoplastic polyurethane/graphene oxide scaffolds for small diameter vascular graft applications.

    Science.gov (United States)

    Jing, Xin; Mi, Hao-Yang; Salick, Max R; Cordie, Travis M; Peng, Xiang-Fang; Turng, Lih-Sheng

    2015-04-01

    Fabrication of small diameter vascular grafts plays an important role in vascular tissue engineering. In this study, thermoplastic polyurethane (TPU)/graphene oxide (GO) scaffolds were fabricated via electrospinning at different GO contents as potential candidates for small diameter vascular grafts. In terms of mechanical and surface properties, the tensile strength, Young's modulus, and hydrophilicity of the scaffolds increased with an increase of GO content while plasma treatment dramatically improved the scaffold hydrophilicity. Mouse fibroblast (3T3) and human umbilical vein endothelial cells (HUVECs) were cultured on the scaffolds separately to study their biocompatibility and potential to be used as vascular grafts. It was found that cell viability for both types of cells, fibroblast proliferation, and HUVEC attachment were the highest at a 0.5wt.% GO loading whereas oxygen plasma treatment also enhanced HUVEC viability and attachment significantly. In addition, the suture retention strength and burst pressure of tubular TPU/GO scaffolds containing 0.5wt.% GO were found to meet the requirements of human blood vessels, and endothelial cells were able to attach to the inner surface of the tubular scaffolds. Platelet adhesion tests using mice blood indicated that vascular scaffolds containing 0.5% GO had low platelet adhesion and activation. Therefore, the electrospun TPU/GO tubular scaffolds have the potential to be used in vascular tissue engineering.

  8. Migraine can be induced by sildenafil without changes in middle cerebral artery diameter

    DEFF Research Database (Denmark)

    Kruuse, Christina Rostrup; Thomsen, Lars Lykke; Birk, Steffen

    2003-01-01

    CBF(mca)) was measured using SPECT (single photon emission computed tomography) and xenon 133 inhalation. Radial and temporal artery diameters were studied using high-frequency ultrasonography. Headache response, tenderness of pericranial muscles, blood pressure and heart rate were measured repeatedly. We found...... that migraine attack was induced by sildenafil in 10 of 12 migraine patients and by placebo in two of 12 patients (P = 0.01). V(mca) (P = 0.1) and rCBF(mca) (P = 0.93) remained unchanged after sildenafil. Temporal (P = 0.47) and radial (P = 0.87) artery diameter and pericranial tenderness (P = 0.16) were...... unaffected by sildenafil. Systolic and diastolic blood pressures were unchanged but heart rate increased from a mean of 62 +/- 2 to 74 +/- 3 beats/min (P = 0.01) after sildenafil. Our results demonstrate that migraine may be induced via a cGMP-dependent mechanism, and we show for the first time...

  9. Microstrain-level measurement of third-order elastic constants applying dynamic acousto-elastic testing

    Science.gov (United States)

    Renaud, Guillaume; Talmant, Maryline; Marrelec, Guillaume

    2016-10-01

    The nonlinear elasticity of solids at the microstrain level has been recently studied by applying dynamic acousto-elastic testing. It is the analog of conventional quasi-static acousto-elastic experiments but the strain-dependence (or stress-dependence) of ultrasonic wave-speed is measured with an applied strain ranging from 10-7 to 10-5 and produced by a stationary elastic wave. In conventional quasi-static acousto-elastic experiments, the strain is applied in a quasi-static manner; it exceeds 10-4 and can reach 10-2. In this work, we apply dynamic acousto-elastic testing to measure the third-order elastic constants of two isotropic materials: polymethyl methacrylate and dry Berea sandstone. The peak amplitude of the dynamic applied strain is 8 × 10-6. The method is shown to be particularly suitable for materials exhibiting large elastic nonlinearity like sandstones, since the measurement is performed in the domain of validity of the third-order hyperelastic model. In contrast, conventional quasi-static acousto-elastic experiments in such materials are often performed outside the domain of validity of the third-order hyperelastic model and the stress-dependence of the ultrasonic wave-speed must be extrapolated at zero stress, leading to approximate values of the third-order elastic constants. The uncertainty of the evaluation of the third-order elastic constants is assessed by repeating multiple times the measurements and with Monte-Carlo simulations. The obtained values of the Murnaghan third-order elastic constants are l = -73 GPa ± 9%, m = -34 GPa ± 9%, and n = -61 GPa ± 10% for polymethyl methacrylate, and l = -17 000 GPa ± 20%, m = -11 000 GPa ± 10%, and n = -30 000 GPa ± 20% for dry Berea sandstone.

  10. Positron interactions with water–total elastic, total inelastic, and elastic differential cross section measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tattersall, Wade [Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Centre for Antimatter-Matter Studies, School of Engineering and Physical Sciences, James Cook University, Townsville, 4810 Queensland (Australia); Chiari, Luca [Centre for Antimatter-Matter Studies, School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide 5001, South Australia (Australia); Machacek, J. R.; Anderson, Emma; Sullivan, James P. [Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); White, Ron D. [Centre for Antimatter-Matter Studies, School of Engineering and Physical Sciences, James Cook University, Townsville, 4810 Queensland (Australia); Brunger, M. J. [Centre for Antimatter-Matter Studies, School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide 5001, South Australia (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Buckman, Stephen J. [Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Garcia, Gustavo [Instituto de Fısica Fundamental, Consejo Superior de Investigationes Cientıficas (CSIC), Serrano 113-bis, E-28006 Madrid (Spain); Blanco, Francisco [Departamento de Fısica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2014-01-28

    Utilising a high-resolution, trap-based positron beam, we have measured both elastic and inelastic scattering of positrons from water vapour. The measurements comprise differential elastic, total elastic, and total inelastic (not including positronium formation) absolute cross sections. The energy range investigated is from 1 eV to 60 eV. Comparison with theory is made with both R-Matrix and distorted wave calculations, and with our own application of the Independent Atom Model for positron interactions.

  11. Positron interactions with water-total elastic, total inelastic, and elastic differential cross section measurements.

    Science.gov (United States)

    Tattersall, Wade; Chiari, Luca; Machacek, J R; Anderson, Emma; White, Ron D; Brunger, M J; Buckman, Stephen J; Garcia, Gustavo; Blanco, Francisco; Sullivan, James P

    2014-01-28

    Utilising a high-resolution, trap-based positron beam, we have measured both elastic and inelastic scattering of positrons from water vapour. The measurements comprise differential elastic, total elastic, and total inelastic (not including positronium formation) absolute cross sections. The energy range investigated is from 1 eV to 60 eV. Comparison with theory is made with both R-Matrix and distorted wave calculations, and with our own application of the Independent Atom Model for positron interactions.

  12. Cord Blood

    Directory of Open Access Journals (Sweden)

    Saeed Abroun

    2014-05-01

    Full Text Available   Stem cells are naïve or master cells. This means they can transform into special 200 cell types as needed by body, and each of these cells has just one function. Stem cells are found in many parts of the human body, although some sources have richer concentrations than others. Some excellent sources of stem cells, such as bone marrow, peripheral blood, cord blood, other tissue stem cells and human embryos, which last one are controversial and their use can be illegal in some countries. Cord blood is a sample of blood taken from a newborn baby's umbilical cord. It is a rich source of stem cells, umbilical cord blood and tissue are collected from material that normally has no use following a child’s birth. Umbilical cord blood and tissue cells are rich sources of stem cells, which have been used in the treatment of over 80 diseases including leukemia, lymphoma and anemia as bone marrow stem cell potency.  The most common disease category has been leukemia. The next largest group is inherited diseases. Patients with lymphoma, myelodysplasia and severe aplastic anemia have also been successfully transplanted with cord blood. Cord blood is obtained by syringing out the placenta through the umbilical cord at the time of childbirth, after the cord has been detached from the newborn. Collecting stem cells from umbilical blood and tissue is ethical, pain-free, safe and simple. When they are needed to treat your child later in life, there will be no rejection or incompatibility issues, as the procedure will be using their own cells. In contrast, stem cells from donors do have these potential problems. By consider about cord blood potency, cord blood banks (familial or public were established. In IRAN, four cord blood banks has activity, Shariati BMT center cord blood bank, Royan familial cord blood banks, Royan public cord blood banks and Iranian Blood Transfusion Organ cord blood banks. Despite 50,000 sample which storage in these banks, but the

  13. Forming limits under multi-index constraints in NC bending of aluminum alloy thin-walled tubes with large diameters

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    With increasing diameters of aluminum alloy thin-walled tubes (AATTs), the tube forming limits, i.e. the minimum bending factors, and their predictions under multi-index constraints including wrinkling, thinning and flattening have been being a key problem to be urgently solved for improving tube forming potential in numerical control (NC) bending processes of AATTs with large diameters. Thus in this paper, a search algorithm of the forming limits is put forward based on a 3D elastic-plastic finite element (FE) model and a wrinkling energy prediction model for the bending processes under axial compression loading (ACL) or not. This algorithm enables to be considered the effects of process parameter combinations including die, friction parameters on the multi-indices. Based on this algorithm, the forming limits of the different size tubes are obtained, and the roles of the process parameter combinations in enabling the limit bending processes are also revealed. The followings are found: the first, within the appropriate ranges of friction and clearances between the different dies and the tubes enabling the bending processes with smaller bending factors, the ACL enables the tube limit bending processes after a decrease of the mandrel ball thickness and diameters; then, without considering the effects of the tube geometry sizes on the tube constitutive equations, the forming limits will be decided by the limit thinning values for the tubes with diameters smaller than 80 mm, while the wrinkling for the tubes with diameters no less than 80 mm. The forming limits obtained from this algorithm are smaller than the analytical results, and reduced by 57.39%; the last, the roles of the process parameter combinations in enabling the limit bending processes are verified by experimental results.

  14. On Some Elastic Instabilities in Biaxial Nematics

    OpenAIRE

    Sukumaran, Sreejith; G. Ranganath

    1997-01-01

    Within the framework of the continuum elastic theory of biaxial nematic liquid crystals, we have addressed ourselves to the structure, stability and energetics of some singular and non–singular topological defects, and certain director configurations. We find that certain non–singular hybrid disclinations could be energetically favourable relative to certain half–strength disclinations. The interaction between singular hybrids depends strongly on the biaxial elastic anisotropy. We suggest pos...

  15. Fracture imaging with converted elastic waves

    Energy Technology Data Exchange (ETDEWEB)

    Nihei, K.T.; Nakagawa, S.; Myer, L.R.

    2001-05-29

    This paper examines the seismic signatures of discrete, finite-length fractures, and outlines an approach for elastic, prestack reverse-time imaging of discrete fractures. The results of this study highlight the importance of incorporating fracture-generated P-S converted waves into the imaging method, and presents an alternate imaging condition that can be used in elastic reverse-time imaging when a direct wave is recorded (e.g., for crosswell and VSP acquisition geometries).

  16. Import price elasticities: reconsidering the evidence

    OpenAIRE

    Hélène Erkel-Rousse; Daniel Mirza

    2002-01-01

    Recent economic geography and trade empirical studies based on monopolistic competition suggest high levels of trade price elasticities (between 3 and 11). However, price elasticity estimations in trade equations using unit values as price proxies usually lead to lower values of around unity. We show that those inconclusive results may be due to some misspecification in these equations as well as measurement errors in prices. When suitable instrumental variables are used, within a panel of in...

  17. Visco-elastic response of thermoplastics

    OpenAIRE

    Kristensen, Vegard Berge

    2013-01-01

    In this study a recently developed visco-elastic visco-plastic material model has been evaluated with the intention of improving the simulated behaviour of polymers. In order for polymers to become a more reliable construction material the behaviour has to be rendered realistically in simulations. A set of eleven experimental tests have been conducted to establish a database for further simulations. By use of some of these experimental tests the visco-elastic visco-plastic material model has ...

  18. Control Plane Strategies for Elastic Optical Networks

    DEFF Research Database (Denmark)

    Turus, Ioan

    The goal of this Ph.d. project is to present and address selected challenges related to the increasing traffic demand and limited available capacity in core optical fiber infrastructure in parallel with tighter requirements of reducing energy consumption and operational costs. Elastic Optical...... consumption. EONs offer the opportunity of deploying energy efficiency strategies, which benefit from the flexible nature of elastic optoelectronic devices. This thesis proposes and investigates different approaches for reducing power consumption based on EONs in realistic dynamic traffic scenarios....

  19. Elastic form factors at higher CEBAF energies

    Energy Technology Data Exchange (ETDEWEB)

    Petratos, G.G. [Kent State Univ., OH (United States)

    1994-04-01

    The prospects for elastic scattering from few body systems with higher beam energies at CEBAF is presented. The deuteron and{sup 3}He elastic structure functions A(Q{sup 2}) can be measured at sufficiently high momentum transfers to study the transition between the conventional meson-nucleon and the constituent quark-gluon descriptions. Possible improvements in the proton magnetic form factor data are also presented.

  20. Elasticity of a quantum monolayer solid

    DEFF Research Database (Denmark)

    Bruch, Ludwig Walter

    1992-01-01

    A perturbation-theory formulation of the zero-temperature elastic constants is used to verify symmetry relations for a (monolayer) triangluar lattice. A generalization of the Cauchy relation between the two elastic constants of the triangular lattice with central-pair-potential interactions is gi...... is given for the quantum solid. The first-order quantum corrections are rederived in this formalism, and previous calculations are reanalyzed....

  1. Import price elasticities: reconsidering the evidence

    OpenAIRE

    Hélène Erkel-Rousse; Daniel Mirza

    2002-01-01

    Recent economic geography and trade empirical studies based on monopolistic competition suggest high levels of trade price elasticities (between 3 and 11). However, price elasticity estimations in trade equations using unit values as price proxies usually lead to lower values of around unity. We show that those inconclusive results may be due to some misspecification in these equations as well as measurement errors in prices. When suitable instrumental variables are used, within a panel of in...

  2. Plane strain problem in microstretch elastic solid

    Indian Academy of Sciences (India)

    Rajneesh Kumar; Ranjit Singh; T K Chadha

    2003-12-01

    The eigenvalue approach is developed for the two-dimensional plane strain problem in a microstretch elastic medium. Applying Laplace and Fourier transforms, an infinite space subjected to a concentrated force is studied. The integral transforms are inverted using a numerical technique to get displacement, force stress, couple stress and first moment, which are also shown graphically. The results of micropolar elasticity are deduced as a special case from the present formulation.

  3. A constant elasticity of profit production function

    OpenAIRE

    Beard, Rodney

    2007-01-01

    Impact analysis of changes in production inputs may be simplified if one can apply a constant adjustment factor to profit. In particular, if a production function can be found for which the elasticity of profit is constant and this function has desirable properties, then one can use the input elasticity of profit to study the impact of input changes on profit. In this paper such a production function is derived from first principles.

  4. Income Elasticity Literature Review | Science Inventory | US ...

    Science.gov (United States)

    Following advice from the SAB Council, when estimating the economic value of reductions in air pollution-related mortality and morbidity risk, EPA accounts for the effect of personal income on the willingness to pay to reduce the risk of adverse health outcomes. These income growth adjustment factors are calculated using a combination of income elasticity estimates and income growth projections, both of which have remained essentially unchanged since 1999. These income elasticity estimates vary according to the severity of illness. EPA recently received advice from the SAB regarding the range of income elasticities to apply as well as the research standards to use when selecting income elasticity estimates. Following this advice, EPA consulted with a contractor to update its income elasticity and income growth projections, and generate new income growth adjustment factors. The SAB would evaluate the income elasticity estimates identified in the EPA-provided literature review, determining the extent to which these estimates are appropriate to use in human health benefits assessments.

  5. TOPICAL REVIEW: Inverse problems in elasticity

    Science.gov (United States)

    Bonnet, Marc; Constantinescu, Andrei

    2005-04-01

    This review is devoted to some inverse problems arising in the context of linear elasticity, namely the identification of distributions of elastic moduli, model parameters or buried objects such as cracks. These inverse problems are considered mainly for three-dimensional elastic media under equilibrium or dynamical conditions, and also for thin elastic plates. The main goal is to overview some recent results, in an effort to bridge the gap between studies of a mathematical nature and problems defined from engineering practice. Accordingly, emphasis is given to formulations and solution techniques which are well suited to general-purpose numerical methods for solving elasticity problems on complex configurations, in particular the finite element method and the boundary element method. An underlying thread of the discussion is the fact that useful tools for the formulation, analysis and solution of inverse problems arising in linear elasticity, namely the reciprocity gap and the error in constitutive equation, stem from variational and virtual work principles, i.e., fundamental principles governing the mechanics of deformable solid continua. In addition, the virtual work principle is shown to be instrumental for establishing computationally efficient formulae for parameter or geometrical sensitivity, based on the adjoint solution method. Sensitivity formulae are presented for various situations, especially in connection with contact mechanics, cavity and crack shape perturbations, thus enriching the already extensive known repertoire of such results. Finally, the concept of topological derivative and its implementation for the identification of cavities or inclusions are expounded.

  6. Elastic modulus of cetacean auditory ossicles.

    Science.gov (United States)

    Tubelli, Andrew A; Zosuls, Aleks; Ketten, Darlene R; Mountain, David C

    2014-05-01

    In order to model the hearing capabilities of marine mammals (cetaceans), it is necessary to understand the mechanical properties, such as elastic modulus, of the middle ear bones in these species. Biologically realistic models can be used to investigate the biomechanics of hearing in cetaceans, much of which is currently unknown. In the present study, the elastic moduli of the auditory ossicles (malleus, incus, and stapes) of eight species of cetacean, two baleen whales (mysticete) and six toothed whales (odontocete), were measured using nanoindentation. The two groups of mysticete ossicles overall had lower average elastic moduli (35.2 ± 13.3 GPa and 31.6 ± 6.5 GPa) than the groups of odontocete ossicles (53.3 ± 7.2 GPa to 62.3 ± 4.7 GPa). Interior bone generally had a higher modulus than cortical bone by up to 36%. The effects of freezing and formalin-fixation on elastic modulus were also investigated, although samples were few and no clear trend could be discerned. The high elastic modulus of the ossicles and the differences in the elastic moduli between mysticetes and odontocetes are likely specializations in the bone for underwater hearing.

  7. Twelve Elastic Constants of Betula platyphylla Suk.

    Institute of Scientific and Technical Information of China (English)

    Wang Liyu; Lu Zhenyou

    2004-01-01

    Wood elastic constants are needed to describe the elastic behaviors of wood and be taken as an important design parameter for wood-based composite materials and structural materials. This paper clarified the relationships between compliance coefficients and engineering elastic constants combined with orthotropic properties of wood, and twelve elastic constants of Betula platyphylla Suk. were measured by electrical strain gauges. Spreading the adhesive quantity cannot be excessive or too little when the strain flakes were glued. If excessive, the glue layer was too thick which would influence the strain flakes' performance, and if too little, glues plastered were not firm, which could not accurately transmit the strain. Wood as an orthotropic material, its modulus of elasticity and poisson's ratios are related by two formulas:μij /Ei =μji /Ej and μij 0.95) between the reciprocal of elastic modulus MOE-1 and the square of the ratio of depth to length (h/l)2, which indicate that shear modulus values measured were reliable by three point bending experiment.

  8. Elastic reflection waveform inversion with variable density

    KAUST Repository

    Li, Yuanyuan

    2017-08-17

    Elastic full waveform inversion (FWI) provides a better description of the subsurface than those given by the acoustic assumption. However it suffers from a more serious cycle skipping problem compared with the latter. Reflection waveform inversion (RWI) provides a method to build a good background model, which can serve as an initial model for elastic FWI. Therefore, we introduce the concept of RWI for elastic media, and propose elastic RWI with variable density. We apply Born modeling to generate the synthetic reflection data by using optimized perturbations of P- and S-wave velocities and density. The inversion for the perturbations in P- and S-wave velocities and density is similar to elastic least-squares reverse time migration (LSRTM). An incorrect initial model will lead to some misfits at the far offsets of reflections; thus, can be utilized to update the background velocity. We optimize the perturbation and background models in a nested approach. Numerical tests on the Marmousi model demonstrate that our method is able to build reasonably good background models for elastic FWI with absence of low frequencies, and it can deal with the variable density, which is needed in real cases.

  9. Factors influencing the diameter of human anterior and posterior intercostal arteries.

    Science.gov (United States)

    Kuhlman, David R; Khuder, Sadik A; Lane, Richard D

    2015-03-01

    At present, there have not been any detailed studies examining the size relationships of the intercostal arteries. This study was carried out to investigate the relationship between the vessel lumenal diameter of ipsilateral, paired anterior and posterior IC arteries, as well as with the length of the IC space supplied by each artery. Samples were collected from the second-sixth anterior and posterior IC arteries near their site of origin, and the lengths of the corresponding IC spaces were measured in 42 cadavers. Lumenal diameters of both the anterior and posterior IC arteries at consecutive IC space closely followed second degree polynomial regression models (R(2) = 0.9655, and R(2) = 0.9741, respectively), and reached maximum size at the fifth IC space, which was found to be the longest of the IC spaces. No direct relationship was observed between diameters of the paired anterior and posterior IC arteries, although there was a trend for the larger anterior IC arteries to be paired with the larger posterior IC arteries. The calculated rate of blood flow at each IC artery was approximately two-fold greater in males than in females. These results suggest that the length of the IC space, and hence the extent of the thoracic wall supplied, is a major factor in determining the diameter of both anterior and posterior IC arteries. Since COPD is such a prevalent disease, this study also examined its influence on the IC arteries, and found that the posterior IC arteries are significantly larger among afflicted subjects. © 2014 Wiley Periodicals, Inc.

  10. Blood pressure estimation in the human fetal descending aorta.

    NARCIS (Netherlands)

    Struijk, P.C.; Mathews, V.J.; Loupas, T.; Stewart, P.A.; Clark, E.B.; Steegers, E.A.P.; Wladimiroff, J.W.

    2008-01-01

    OBJECTIVES: The objectives of this study were to estimate fetal blood pressure non-invasively from two-dimensional color Doppler-derived aortic blood flow and diameter waveforms, and to compare the results with invasively derived human fetal blood pressures available from the literature. METHODS:

  11. Blood pressure estimation in the human fetal descending aorta

    NARCIS (Netherlands)

    P.C. Struijk (Pieter); V.J. Mathews; T. Loupas; P.A. Stewart (Patricia); E.B. Clark; R.P.M. Steegers-Theunissen (Régine); J.W. Wladimiroff (Juriy)

    2008-01-01

    textabstractObjectives: The objectives of this study were to estimate fetal blood pressure non-invasively from two-dimensional color Doppler-derived aortic blood flow and diameter waveforms, and to compare the results with invasively derived human fetal blood pressures available from the literature.

  12. Mixed effect models for predicting breast height diameter from stump diameter of Oriental beech in Göldağ

    Directory of Open Access Journals (Sweden)

    Ilker Ercanli

    2015-06-01

    Full Text Available Diameter at breast height (DBH is the simplest, most common and most important tree dimension in forest inventory and is closely correlated with wood volume, height and biomass. In this study, a number of linear and nonlinear models predicting diameter at breast height from stump diameter were developed and evaluated for Oriental beech (Fagus orientalisLipsky stands located in the forest region of Ayancık, in the northeast of Turkey. A set of 1,501 pairs of diameter at breast height-stump measurements, originating from 70 sample plots of even-aged Oriental beech stands, were used in this study. About 80 % of the otal data (1,160 trees in 55 sample plots was used to fit a number of linear and nonlinear model parameters; the remaining 341 trees in 15 sample plots were randomly reserved for model validation and calibration response. The power model data set was found to produce the most satisfactory fits with the Adjusted Coefficient of Determination, R2adj (0.990, Root Mean Square Error, RMSE (1.25, Akaike’s Information Criterion, AIC (3820.5, Schwarz’s Bayesian Information Criterion, BIC (3837.2, and Absolute Bias (1.25. The nonlinear mixed-effect modeling approach for power model with R2adj(0.993, AIC (3598, BIC (3610.1, Absolute Bias (0.73 and RMSE (1.04 provided much better fitting and precise predictions for DBH from stump diameter than the conventional nonlinear fixed effect model structures for this model. The calibration response including tree DBH and stump diameter measurements of the four largest trees in a calibrated sample plot in calibration produced the highest Bias, -5.31 %, and RMSE, -6.30 %, the greatest reduction percentage.

  13. Uncertainty budget for optical coordinate measurements of circle diameter

    DEFF Research Database (Denmark)

    Morace, Renate Erica; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2004-01-01

    An uncertainty analysis for circle diameter measurements using a coordinate measuring machine (CMM) equipped with an optical probe is presented in this paper. A mathematical model for data evaluation and uncertainty assessment was formulated in accordance with Guide to the Expression of Uncertain...

  14. Experimental study on strain sensing by small-diameter FBG

    Science.gov (United States)

    Liu, Rong-mei; Li, Qiufeng; Zhu, Lujia; Liang, Dakai

    2016-11-01

    Fiber Bragg grating (FBG) sensors were attractive in various fields for structural health monitoring. Because of their accurate performance and real time response, embedded FBG sensors are promising for strain monitoring in composite materials. As an optical fiber sensor was embedded inside a composite, interface would form around the embedded optical fiber and the host polymer composite. In order to study the influence of the embedded optical fiber to the mechanical character, finite elemental analysis was applied to study the stress distribution inside the composite. Keeping the resin rich area the same size, laminates with optical fibers in different diameters, which were 250 and 125 micrometers, were analyzed. The simulation results represent that stress singularity would occur around the embedded optical fiber. The singularity value for the laminate with optical fiber at 250 micrometer was higher than that with optical fiber at 125 micrometer. Micro- cracks would arise at the stress singularity point. Therefore, the optical fiber in smaller diameter was preferred since the mechanical strength could be higher. Four points bending test was carried out on a steel beam with a small-diameter FBG on the bottom surface. Besides, a strain gauge was stuck on bottom to validate the monitoring results by FBG sensor. The tested results indicated that the strain monitoring results by the small-diameter FBG sensor almost identical with the theoretical ones and what recorded by strain gauge. The maximum testing error for the designed FBG is less than 2% compared with the theoretical one.

  15. Predicted and observed finger diameters in field soils

    NARCIS (Netherlands)

    Ritsema, C.J.; Steenhuis, T.S.; Parlange, J.Y.; Dekker, L.W.

    1996-01-01

    Wetting front instability resulting in fingered flow has been found in both wettable and non-wettable soils. Laboratory research has resulted in a number of expressions for finger diameter. The applicability of one of these equations was tested for three soils where detailed soil moisture contents w

  16. Pupil diameter covaries with BOLD activity in human locus coeruleus.

    Science.gov (United States)

    Murphy, Peter R; O'Connell, Redmond G; O'Sullivan, Michael; Robertson, Ian H; Balsters, Joshua H

    2014-08-01

    The locus coeruleus-noradrenergic (LC-NA) neuromodulatory system has been implicated in a broad array of cognitive processes, yet scope for investigating this system's function in humans is currently limited by an absence of reliable non-invasive measures of LC activity. Although pupil diameter has been employed as a proxy measure of LC activity in numerous studies, empirical evidence for a relationship between the two is lacking. In the present study, we sought to rigorously probe the relationship between pupil diameter and BOLD activity localized to the human LC. Simultaneous pupillometry and fMRI revealed a relationship between continuous pupil diameter and BOLD activity in a dorsal pontine cluster overlapping with the LC, as localized via neuromelanin-sensitive structural imaging and an LC atlas. This relationship was present both at rest and during performance of a two-stimulus oddball task, with and without spatial smoothing of the fMRI data, and survived retrospective image correction for physiological noise. Furthermore, the spatial extent of this pupil/LC relationship guided a volume-of-interest analysis in which we provide the first demonstration in humans of a fundamental characteristic of animal LC activity: phasic modulation by oddball stimulus relevance. Taken together, these findings highlight the potential for utilizing pupil diameter to achieve a more comprehensive understanding of the role of the LC-NA system in human cognition.

  17. Rowlinson’s concept of an effective hard sphere diameter

    Science.gov (United States)

    Henderson, Douglas

    2010-01-01

    Attention is drawn to John Rowlinson’s idea that the repulsive portion of the intermolecular interaction may be replaced by a temperature-dependent hard sphere diameter. It is this approximation that made the development of perturbation theory possible for realistic fluids whose intermolecular interactions have a steep, but finite, repulsion at short separations. PMID:20953320

  18. Rowlinson's concept of an effective hard sphere diameter.

    Science.gov (United States)

    Henderson, Douglas

    2010-01-01

    Attention is drawn to John Rowlinson's idea that the repulsive portion of the intermolecular interaction may be replaced by a temperature-dependent hard sphere diameter. It is this approximation that made the development of perturbation theory possible for realistic fluids whose intermolecular interactions have a steep, but finite, repulsion at short separations.

  19. FACES WITH LARGE DIAMETER ON THE SYMMETRICAL TRAVELING SALESMAN POLYTOPE

    NARCIS (Netherlands)

    SIERKSMA, G; TIJSSEN, GA

    1992-01-01

    This paper deals with the symmetric traveling salesman polytope and contains three main theorems. The first one gives a new characterization of (non)adjacency. Based on this characterization a new upper bound for the diameter of the symmetric traveling salesman polytope (conjectured to be 2 by M. Gr

  20. Definition of Beam Diameter for Electron Beam Welding

    Energy Technology Data Exchange (ETDEWEB)

    Burgardt, Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pierce, Stanley W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dvornak, Matthew John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-11

    It is useful to characterize the dimensions of the electron beam during process development for electron beam welding applications. Analysis of the behavior of electron beam welds is simplest when a single number can be assigned to the beam properties that describes the size of the beam spot; this value we generically call the “beam diameter”. This approach has worked well for most applications and electron beam welding machines with the weld dimensions (width and depth) correlating well with the beam diameter. However, in recent weld development for a refractory alloy, Ta-10W, welded with a low voltage electron beam machine (LVEB), it was found that the weld dimensions (weld penetration and weld width) did not correlate well with the beam diameter and especially with the experimentally determined sharp focus point. These data suggest that the presently used definition of beam diameter may not be optimal for all applications. The possible reasons for this discrepancy and a suggested possible alternative diameter definition is the subject of this paper.

  1. Calibration of Laser Beam Direction for Inner Diameter Measuring Device

    Directory of Open Access Journals (Sweden)

    Tongyu Yang

    2017-02-01

    Full Text Available The laser triangulation method is one of the most advanced methods for large inner diameter measurement. Our research group proposed a kind of inner diameter measuring device that is principally composed of three laser displacement sensors known to be fixed in the same plane measurement position. It is necessary to calibrate the direction of the laser beams that are emitted by laser displacement sensors because they do not meet the theoretical model accurately. For the purpose of calibrating the direction of laser beams, a calibration method and mathematical model were proposed. The inner diameter measuring device is equipped with the spindle of the machine tool. The laser beams rotate and translate in the plane and constitute the rotary rays which are driven to scan the inner surface of the ring gauge. The direction calibration of the laser beams can be completed by the sensors’ distance information and corresponding data processing method. The corresponding error sources are analyzed and the validity of the method is verified. After the calibration, the measurement error of the inner diameter measuring device reduced from ± 25 μ m to ± 15 μ m and the relative error was not more than 0.011%.

  2. Diameter-dependent conductance of InAs nanowires

    NARCIS (Netherlands)

    Scheffler, M.; Nadj-Perge, S.; Kouwenhoven, L.P.; Borgström, M.T.; Bakkers, E.P.A.M.

    2009-01-01

    Electrical conductance through InAs nanowires is relevant for electronic applications as well as for fundamental quantum experiments. Here, we employ nominally undoped, slightly tapered InAs nanowires to study the diameter dependence of their conductance. By contacting multiple sections of each wire

  3. Asteroid magnitudes, UBV colors, and IRAS albedos and diameters

    Science.gov (United States)

    Tedesco, Edward F.

    1989-01-01

    This paper lists absolute magnitudes and slope parameters for known asteroids numbered through 3318. The values presented are those used in reducing asteroid IR flux data obtained with the IRAS. U-B colors are given for 938 asteroids, and B-V colors are given for 945 asteroids. The IRAS albedos and diameters are tabulated for 1790 asteroids.

  4. A small-diameter NMR logging tool for groundwater investigations.

    Science.gov (United States)

    Walsh, David; Turner, Peter; Grunewald, Elliot; Zhang, Hong; Butler, James J; Reboulet, Ed; Knobbe, Steve; Christy, Tom; Lane, John W; Johnson, Carole D; Munday, Tim; Fitzpatrick, Andrew

    2013-01-01

    A small-diameter nuclear magnetic resonance (NMR) logging tool has been developed and field tested at various sites in the United States and Australia. A novel design approach has produced relatively inexpensive, small-diameter probes that can be run in open or PVC-cased boreholes as small as 2 inches in diameter. The complete system, including surface electronics and various downhole probes, has been successfully tested in small-diameter monitoring wells in a range of hydrogeological settings. A variant of the probe that can be deployed by a direct-push machine has also been developed and tested in the field. The new NMR logging tool provides reliable, direct, and high-resolution information that is of importance for groundwater studies. Specifically, the technology provides direct measurement of total water content (total porosity in the saturated zone or moisture content in the unsaturated zone), and estimates of relative pore-size distribution (bound vs. mobile water content) and hydraulic conductivity. The NMR measurements show good agreement with ancillary data from lithologic logs, geophysical logs, and hydrogeologic measurements, and provide valuable information for groundwater investigations.

  5. Estimating Tree Height-Diameter Models with the Bayesian Method

    Directory of Open Access Journals (Sweden)

    Xiongqing Zhang

    2014-01-01

    Full Text Available Six candidate height-diameter models were used to analyze the height-diameter relationships. The common methods for estimating the height-diameter models have taken the classical (frequentist approach based on the frequency interpretation of probability, for example, the nonlinear least squares method (NLS and the maximum likelihood method (ML. The Bayesian method has an exclusive advantage compared with classical method that the parameters to be estimated are regarded as random variables. In this study, the classical and Bayesian methods were used to estimate six height-diameter models, respectively. Both the classical method and Bayesian method showed that the Weibull model was the “best” model using data1. In addition, based on the Weibull model, data2 was used for comparing Bayesian method with informative priors with uninformative priors and classical method. The results showed that the improvement in prediction accuracy with Bayesian method led to narrower confidence bands of predicted value in comparison to that for the classical method, and the credible bands of parameters with informative priors were also narrower than uninformative priors and classical method. The estimated posterior distributions for parameters can be set as new priors in estimating the parameters using data2.

  6. Real-time precision measuring device of tree diameter growth

    Science.gov (United States)

    Guo, Mingming; Chen, Aijun; Li, Dongsheng; Liu, Nan; Yao, Jingyuan

    2016-01-01

    DBH(diameter at breast height) is an important factor to reflect of the quality of plant growth, also an important parameter indispensable in forest resources inventory and forest carbon sink, the accurate measurement of DBH or not is directly related to the research of forest resources inventory and forest carbon sink. In this paper, the principle and the mathematical model of DBH measurement device were introduced, the fixture measuring device and the hardware circuit for this tree diameter were designed, the measurement software programs were compiled, and the precision measuring device of tree diameter growth was developed. Some experiments with Australia fir were conducted. Based on experiment data, the correlations among the DBH variation of Australian fir, the environment temperature, air humility and PAR(photosynthetically active radiation) were obtained. The effects of environmental parameters (environment temperature, air humility and PAR) on tree diameter were analyzed. Experimental results show that there is a positive correlation between DBH variation of Australian fir and environment temperature, a negative correlation between DBH variation of Australian fir and air humility , so is PAR.

  7. The Angular Diameter and Fundamental Parameters of Sirius A

    CERN Document Server

    Davis, J; North, J R; Robertson, J G; Tango, W J; Tuthill, P G

    2010-01-01

    The Sydney University Stellar Interferometer (SUSI) has been used to make a new determination of the angular diameter of Sirius A. The observations were made at an effective wavelength of 694.1 nm and the new value for the limb-darkened angular diameter is 6.048 +/- 0.040mas (+/-0.66%). This new result is compared with previous measurements and is found to be in excellent agreement with a conventionally calibrated measurement made with the European Southern Observatory's Very Large Telescope Interferometer (VLTI) at 2.176 microns (but not with a second globally calibrated VLTI measurement). A weighted mean of the SUSI and first VLTI results gives the limb-darkened angular diameter of Sirius A as 6.041 +/- 0.017mas (+/-0.28%). Combination with the Hipparcos parallax gives the radius equal to 1.713 +/- 0.009R_sun. The bolometric flux has been determined from published photometry and spectrophotometry and, combined with the angular diameter, yields the emergent flux at the stellar surface equal to (5.32+/- 0.14)...

  8. Observations on placentome diameters in gestating West African ...

    African Journals Online (AJOL)

    ADEYEYE

    2015-09-09

    Sep 9, 2015 ... Department of Veterinary Surgery and Reproduction, University of Ibadan, Ibadan, Nigeria ... This study investigated the effect of experimental Trypanosoma brucei infection on the placentome diameter (PD) ... symptoms/clinical signs in female mammalian ..... Global Library Women's Medicine, London,.

  9. Small-diameter trees used for chemithermomechanical pulps.

    Science.gov (United States)

    Gary C. Myers; R. James. Barbour; Said M. Abubakr

    1999-01-01

    During the course of restoring and maintaining forest ecosystem health and function in the western interior of the United States, many small-diameter stems are removed from densely stocked stands. In general, these materials are considered nonusable or underutilized. Information on the properties of these resources is needed to help managers understand when timber...

  10. Processing of fine-diameter continuous mullite fibers

    Energy Technology Data Exchange (ETDEWEB)

    Al-Assafi, S.; Cruse, T.; Simmons, J.H. [Univ. of Florida, Gainesville, FL (United States)] [and others

    1994-12-31

    Fine-diameter, continuous mullite fibers were fabricated by sol-gel processing using two different chelating agents on weight loss behavior, mullite formation, and sintered fiber microstructure were examined. The molar ratio, R, of chelating agent to alumina precursor in the sol was varied in order to optimize continuous spinning conditions. The importance of aging conditions on the sintered fiber density was demonstrated.

  11. Bipartite Diametrical Graphs of Diameter 4 and Extreme Orders

    Directory of Open Access Journals (Sweden)

    Salah Al-Addasi

    2008-01-01

    in which this upper bound is attained, this graph can be viewed as a generalization of the Rhombic Dodecahedron. Then we show that for any ≥2, the graph (2,2 is the unique (up to isomorphism bipartite diametrical graph of diameter 4 and partite sets of cardinalities 2 and 2, and hence in particular, for =3, the graph (6,8 which is just the Rhombic Dodecahedron is the unique (up to isomorphism bipartite diametrical graph of such a diameter and cardinalities of partite sets. Thus we complete a characterization of -graphs of diameter 4 and cardinality of the smaller partite set not exceeding 6. We prove that the neighborhoods of vertices of the larger partite set of (2,2 form a matroid whose basis graph is the hypercube . We prove that any -graph of diameter 4 is bipartite self complementary, thus in particular (2,2. Finally, we study some additional properties of (2,2 concerning the order of its automorphism group, girth, domination number, and when being Eulerian.

  12. Elastic deformation behaviour of Palaeogene clay from Fehmarn Belt area

    DEFF Research Database (Denmark)

    Awadalkarim, Ahmed; Foged, Niels Nielsen; Fabricius, Ida Lykke

    2014-01-01

    clays. Elastic wave velocities are influenced by the elastic stiffness and the density of a material. We used geotechnical and elastic wave velocity data to model the elasticity and then to relate it to mineralogy and BET surface area. We measured the mineralogy, BET surface area, bulk density, porosity...

  13. Parameter Optimisation for the Behaviour of Elastic Models over Time

    DEFF Research Database (Denmark)

    Mosegaard, Jesper

    2004-01-01

    Optimisation of parameters for elastic models is essential for comparison or finding equivalent behaviour of elastic models when parameters cannot simply be transferred or converted. This is the case with a large range of commonly used elastic models. In this paper we present a general method...... that will optimise parameters based on the behaviour of the elastic models over time....

  14. Multi-diameter pigging: factors affecting the design and selection of pigging tools for multi-diameter pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, Karl [Pipeline Engineering and Supply Co. Ltd., Richmond, NY (United States)

    2009-07-01

    This paper will consider the process involved in pigging tool selection for pipelines with two or more significant internal diameters which require pigging tools capable of negotiating the different internal diameters whilst also carrying out the necessary pipeline cleaning operation. The paper will include an analysis of pipeline features that affect pigging tool selection and then go on to look at other variables that determine the pigging tool design; this will include a step by step guide outlining how the tool is designed, the development of prototype pigs and the importance of testing and validation prior to final deployment in operational pigging programmes. (author)

  15. Vertebral Artery Diameter and Flow: Nature or Nurture.

    Science.gov (United States)

    Tarnoki, Adam Domonkos; Fejer, Bence; Tarnoki, David Laszlo; Littvay, Levente; Lucatelli, Pierleone; Cirelli, Carlo; Fanelli, Fabrizio; Sacconi, Beatrice; Fagnani, Corrado; Medda, Emanuela; Farina, Filippo; Meneghetti, Giorgio; Horvath, Tamas; Pucci, Giacomo; Schillaci, Giuseppe; Stazi, Maria Antonietta; Baracchini, Claudio

    2017-09-01

    In contrast with the carotid arteries, the vertebral arteries (VAs) show considerable variation in length, caliber, and vessel course. This study investigated whether the variation in diameter and flow characteristics of the VAs might be inherited. A total of 172 Italian twins from Padua, Perugia, and Terni (54 monozygotic, 32 dizygotic) recruited from the Italian Twin Registry underwent B-mode and pulsed-wave Doppler ultrasound assessment of their VAs. VA diameters, peak systolic velocity (PSV) and end diastolic velocity (EDV) were assessed at the level of a horizontal V2 segment. Univariate quantitative genetic modeling was performed. Fourteen percent of the sample had VA hypoplasia. Within pair correlation in monozygotic twins was higher than in dizygotics (.552 vs. .229) for VA diameter. Age- and sex-adjusted genetic effect, under the most parsimonious model, accounted for 54.7% (95% CI: 42.2-69.1%) of the variance of VA diameter, and unshared environmental effect for 45.3% (95% CI: 30.9-57.8%). No heritability was found for the PSV of VA, but shared (34.1%; 95% CI: 16.7-53.7%) and unshared (65.9%; 95% CI: 45.9-83.1%) environmental factors determined the variance. EDV of VA is moderately genetically influenced (42.4%; 95% CI: 16.1-64.9%) and also determined by the unshared environment (57.6%; 95% CI: 34.7-83.7%). The diameter of the VAs is moderately genetically determined. Different factors influence the PSV and EDV of VAs, which may highlight the complex hemodynamic background of VA flow and help to understand the vertebral flow anomalies found by ultrasound. Copyright © 2017 by the American Society of Neuroimaging.

  16. Stand diameter distribution modelling and prediction based on Richards function.

    Directory of Open Access Journals (Sweden)

    Ai-guo Duan

    Full Text Available The objective of this study was to introduce application of the Richards equation on modelling and prediction of stand diameter distribution. The long-term repeated measurement data sets, consisted of 309 diameter frequency distributions from Chinese fir (Cunninghamia lanceolata plantations in the southern China, were used. Also, 150 stands were used as fitting data, the other 159 stands were used for testing. Nonlinear regression method (NRM or maximum likelihood estimates method (MLEM were applied to estimate the parameters of models, and the parameter prediction method (PPM and parameter recovery method (PRM were used to predict the diameter distributions of unknown stands. Four main conclusions were obtained: (1 R distribution presented a more accurate simulation than three-parametric Weibull function; (2 the parameters p, q and r of R distribution proved to be its scale, location and shape parameters, and have a deep relationship with stand characteristics, which means the parameters of R distribution have good theoretical interpretation; (3 the ordinate of inflection point of R distribution has significant relativity with its skewness and kurtosis, and the fitted main distribution range for the cumulative diameter distribution of Chinese fir plantations was 0.4∼0.6; (4 the goodness-of-fit test showed diameter distributions of unknown stands can be well estimated by applying R distribution based on PRM or the combination of PPM and PRM under the condition that only quadratic mean DBH or plus stand age are known, and the non-rejection rates were near 80%, which are higher than the 72.33% non-rejection rate of three-parametric Weibull function based on the combination of PPM and PRM.

  17. Stand diameter distribution modelling and prediction based on Richards function.

    Science.gov (United States)

    Duan, Ai-guo; Zhang, Jian-guo; Zhang, Xiong-qing; He, Cai-yun

    2013-01-01

    The objective of this study was to introduce application of the Richards equation on modelling and prediction of stand diameter distribution. The long-term repeated measurement data sets, consisted of 309 diameter frequency distributions from Chinese fir (Cunninghamia lanceolata) plantations in the southern China, were used. Also, 150 stands were used as fitting data, the other 159 stands were used for testing. Nonlinear regression method (NRM) or maximum likelihood estimates method (MLEM) were applied to estimate the parameters of models, and the parameter prediction method (PPM) and parameter recovery method (PRM) were used to predict the diameter distributions of unknown stands. Four main conclusions were obtained: (1) R distribution presented a more accurate simulation than three-parametric Weibull function; (2) the parameters p, q and r of R distribution proved to be its scale, location and shape parameters, and have a deep relationship with stand characteristics, which means the parameters of R distribution have good theoretical interpretation; (3) the ordinate of inflection point of R distribution has significant relativity with its skewness and kurtosis, and the fitted main distribution range for the cumulative diameter distribution of Chinese fir plantations was 0.4∼0.6; (4) the goodness-of-fit test showed diameter distributions of unknown stands can be well estimated by applying R distribution based on PRM or the combination of PPM and PRM under the condition that only quadratic mean DBH or plus stand age are known, and the non-rejection rates were near 80%, which are higher than the 72.33% non-rejection rate of three-parametric Weibull function based on the combination of PPM and PRM.

  18. Measurement error in CT assessment of appendix diameter

    Energy Technology Data Exchange (ETDEWEB)

    Trout, Andrew T.; Towbin, Alexander J. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, MLC 5031, Cincinnati, OH (United States); Zhang, Bin [Cincinnati Children' s Hospital Medical Center, Department of Biostatistics and Epidemiology, Cincinnati, OH (United States)

    2016-12-15

    Appendiceal diameter continues to be cited as an important criterion for diagnosis of appendicitis by computed tomography (CT). To assess sources of error and variability in appendiceal diameter measurements by CT. In this institutional review board-approved review of imaging and medical records, we reviewed CTs performed in children <18 years of age between Jan. 1 and Dec. 31, 2010. Appendiceal diameter was measured in the axial and coronal planes by two reviewers (R1, R2). One year later, 10% of cases were remeasured. For patients who had multiple CTs, serial measurements were made to assess within patient variability. Measurement differences between planes, within and between reviewers, within patients and between CT and pathological measurements were assessed using correlation coefficients and paired t-tests. Six hundred thirty-one CTs performed in 519 patients (mean age: 10.9 ± 4.9 years, 50.8% female) were reviewed. Axial and coronal measurements were strongly correlated (r = 0.92-0.94, P < 0.0001) with coronal plane measurements significantly larger (P < 0.0001). Measurements were strongly correlated between reviewers (r = 0.89-0.9, P < 0.0001) but differed significantly in both planes (axial: +0.2 mm, P=0.003; coronal: +0.1 mm, P=0.007). Repeat measurements were significantly different for one reviewer only in the axial plane (0.3 mm difference, P<0.05). Within patients imaged multiple times, measured appendix diameters differed significantly in the axial plane for both reviewers (R1: 0.5 mm, P = 0.031; R2: 0.7 mm, P = 0.022). Multiple potential sources of measurement error raise concern about the use of rigid diameter cutoffs for the diagnosis of acute appendicitis by CT. (orig.)

  19. The complexity of elastic fibre biogenesis in the skin--a perspective to the clinical heterogeneity of cutis laxa.

    Science.gov (United States)

    Uitto, Jouni; Li, Qiaoli; Urban, Zsolt

    2013-02-01

    Elastic fibres are critical connective tissue components providing elasticity and resilience to skin and other tissues. These fibres are composed of elastin and a number of elastin-associated microfibrillar proteins that assemble in a complex fibre network in a multi-step process. Multiple cellular processes, including mitochondrial function, specific molecules in the secretory pathways and temporally and spatially ordered production of elastic fibre components, are required for the biogenesis of functional elastic fibres. Abnormalities in these processes can lead to loss of functional elastic fibres manifesting phenotypically as a skin disease. The paradigm of elastic fibre diseases affecting the skin is cutis laxa, a clinically and genetically heterogeneous group of disorders characterized by loose and sagging skin, frequently associated with extracutaneous manifestations in the lungs and the arterial blood vessels. The complexity of cutis laxa is emphasized by the fact that as many as 10 distinct genes can harbour mutations in this and related disorders. Understanding of the pathomechanistic pathways involved in perturbed elastic fibre assembly in cutis laxa provides information potentially helpful for the development of molecular strategies towards treatment of these, currently intractable, diseases.

  20. Elastic Properties of Sedimentary Rocks

    Science.gov (United States)

    Melendez Martinez, Jaime

    Sedimentary rocks are an important research topic since such rocks are associated to sources of ground water as well as oil, gas, and mineral reservoirs. In this work, elastic and physical properties of a variety of sedimentary samples that include glacial sediments, carbonates, shales, one evaporite, and one argillite from a variety of locations are investigated. Assuming vertical transverse isotropy, ultrasonic compressional- and shear-waves (at 1 MHz central frequency) were measured as a function of confining pressure on all samples with the exception of glacial samples which were tested assuming isotropy. Tensile strength tests (Brazilian test) were also carried out on selected glacial samples and, in addition, static-train measurements were conducted on shales and argillite samples. Lithological and textural features of samples were obtained through thin section techniques, scanning electron microscopy images and micro-tomography images. X-ray diffraction and X-Ray fluorescence provided the mineralogical oxides content information. Porosity, density, and pore structure were studied by using a mercury intrusion porosimeter and a helium pycnometer. The wide range of porosities of the studied samples (ranging from a minimum of 1% for shales to a maximum 45% for some glacial sediments) influence the measured velocities since high porosity sample shows an noticeable velocity increment as confining pressure increases as a consequence of closure of microcracks and pores, unlike low porosity samples where increment is quasi-lineal. Implementation of Gassmann's relation to ultrasonic velocities obtained from glacial samples has negligible impact on them when assuming water saturated samples, which suggests that state of saturation it is no so important in defining such velocities and instead they are mainly frame-controlled. On the other hand, velocities measured on carbonate and evaporite samples show that samples are at best weak anisotropic, thus the intrinsic

  1. Body Fat, Abdominal Fat, and Body Fat Distribution Is Related to Left Atrial Diameter in Young Children

    DEFF Research Database (Denmark)

    Dencker, Magnus; Thorsson, Ola; Karlsson, Magnus K

    2012-01-01

    ). Body fat was also calculated as a percentage of body mass (BF%). Body fat distribution (AFM/TBF) was calculated. Echocardiography was performed with two-dimensional guided M-mode. LA diameter was measured and left ventricular mass (LVM) was calculated. Systolic blood pressure and diastolic blood......In adults, the size of the left atria (LA) has important prognostic information. In obese adults, adolescents and children enlargement of LA have been observed. This has not been investigated on a population-based level in young children. We therefore assessed if total body fat mass (TBF...... pressure were measured and maturity assessed according to Tanner. There were significant (P

  2. Immunoelectrophoresis - blood

    Science.gov (United States)

    IEP - serum; Immunoglobulin electrophoresis - blood; Gamma globulin electrophoresis; Serum immunoglobulin electrophoresis; Amyloidosis - electrophoresis serum; Multiple myeloma - serum electrophoresis; Waldenström - serum electrophoresis

  3. An In-vitro Comparison of Force Loss of Orthodontic Non-Latex Elastics.

    Directory of Open Access Journals (Sweden)

    Shiva Alavi

    2014-02-01

    Full Text Available The amount and consistency of the applied forces to the tooth are important factors in tooth movements; therefore, the aim of this study was to compare the initial force and the force loss of three brands of elastics in 24 hours.In this in-vitro study sixty non-latex elastics (3/16 medium from three companies (Forestadent, Dentaurum and Ortho Technology were randomly selected. Two static tests were performed, the first in a dry environment to evaluate the initial force and the other performed in a wet environment (artificial saliva to evaluate the force loss in 24 hours. The Universal testing machine measured the forces after stretching the elastics to three times the lumen diameter. Data were analyzed by repeated measures ANOVA, One-way ANOVA, Tukey-HSD, Paired samples test, and one sample test.The difference between the brands was significant (p=0.002. Force loss was observed in all samples; 4-7.5% force loss occurred after one hour and 19-38% force loss occurred after 24 hours. The average initial force of Forestadent and Ortho Technology was significantly higher than marketed forces (pDentaurum>Ortho-Technology. According to the initial force and force loss percentage it is suggested to replace the non-latex elastics several times a day.

  4. The indentation of pressurized elastic shells: from polymeric capsules to yeast cells

    KAUST Repository

    Vella, D.

    2011-08-10

    Pressurized elastic capsules arise at scales ranging from the 10 m diameter pressure vessels used to store propane at oil refineries to the microscopic polymeric capsules that may be used in drug delivery. Nature also makes extensive use of pressurized elastic capsules: plant cells, bacteria and fungi have stiff walls, which are subject to an internal turgor pressure. Here, we present theoretical, numerical and experimental investigations of the indentation of a linearly elastic shell subject to a constant internal pressure. We show that, unlike unpressurized shells, the relationship between force and displacement demonstrates two linear regimes. We determine analytical expressions for the effective stiffness in each of these regimes in terms of the material properties of the shell and the pressure difference. As a consequence, a single indentation experiment over a range of displacements may be used as a simple assay to determine both the internal pressure and elastic properties of capsules. Our results are relevant for determining the internal pressure in bacterial, fungal or plant cells. As an illustration of this, we apply our results to recent measurements of the stiffness of baker\\'s yeast and infer from these experiments that the internal osmotic pressure of yeast cells may be regulated in response to changes in the osmotic pressure of the external medium.

  5. Impaired Arterial Elasticity Identified by Pulse Waveform Analysis is a Non- invasive Measure for Early Detection of Endothelial Dysfunction

    Institute of Scientific and Technical Information of China (English)

    Tao Jun; Wang Yan; Yang Zhen; Tu Chang; Xu Mingguo; Wang Jiemei

    2004-01-01

    Objectives Endothelial dysfunction is the earliest marker for atherosclerosis and plays key role in the pathogenesis of cardiovascular diseases. The present study was performed to evaluate effect of aging on arterial elasticity by using pulse waveform analysis and investigate whether the changes in arterial elasticity can be used as a non - invasive measure for early detection of endothelial dysfunction.Methods Using modified Windkessel model of the circulation and pulse waveform analysis, C1 large artery and C2 small artery elasticity indices of 204 normal healthy subjects ( age 15 -80 years) were measured.Among them twenty - four male healthy subjects were divided into both the young (age 20 -30 years, n =12) and elderly (age 60 - 70 years, n = 12) groups.We delivered acethycholine (Ach), an endotheliumdependent vasodilator, and sodium nitroprusside(SNP), an endothelium- independent vasodilator, to dermal vessels of the forearm using iontophoresis, respectively, and measured basal and peak blood flow using laser doppler fluximetry. Results C1 large artery and C2 small artery elasticity indices were reduced with advancing age. C 1 large artery and C2 small artery elasticity indices were negatively correlated with age (r= -0.628, p<0.001; r= -0.595, p <0.001).Basal blood flow was similar between the young and elderly groups ( 14.58 ± 3.4 vs 13.52 ± 3.41 PU, p =NS). Peak blood flow induced by Ach was significantly reduced in the elderly group compared with the young group (83.4 ± 11.9 vs 93.75 ± 10. 87 PU, p < 0. 05 ).However, peak blood flow induced by SNP was similar in the two groups ( 119. 17 ± 16.76 vs 128.33 ± 21.29 PU,p = NS). Ach - induced peak blood flow correlated positively with C1 large artery and C2 small artery elasticity indices( r=0.56, p <0.01; r =0.53, p <0.01).Conclusions Advancing age leads to impaired artery elasticity and endothelial dysfun ction. Reduced arterial elasticity is, in parallel, associated with diminished

  6. Experimental determination of third-order elastic constants of diamond.

    Science.gov (United States)

    Lang, J M; Gupta, Y M

    2011-03-25

    To determine the nonlinear elastic response of diamond, single crystals were shock compressed along the [100], [110], and [111] orientations to 120 GPa peak elastic stresses. Particle velocity histories and elastic wave velocities were measured by using laser interferometry. The measured elastic wave profiles were used, in combination with published acoustic measurements, to determine the complete set of third-order elastic constants. These constants represent the first experimental determination, and several differ significantly from those calculated by using theoretical models.

  7. Is the Armington Elasticity Really Constant across Importers?

    OpenAIRE

    Yilmazkuday, Hakan

    2009-01-01

    This paper shows that the Armington elasticity, which refers to both the elasticity of substitution across goods and the price elasticity of demand under the assumption of a large number of varieties, systematically changes from one importer country to another in an international trade context. Then a natural question to ask is "What determines the Armington elasticity?" The answer comes from the distinction between the elasticity of demand with respect to the destination price (i.e., the Arm...

  8. Is the Armington Elasticity Really Constant across Importers?

    OpenAIRE

    Yilmazkuday, Hakan

    2009-01-01

    This paper shows that the Armington elasticity, which refers to both the elasticity of substitution across goods and the price elasticity of demand under the assumption of a large number of varieties, systematically changes from one importer country to another in an international trade context. Then a natural question to ask is "What determines the Armington elasticity?" The answer comes from the distinction between the elasticity of demand with respect to the destination price (i.e., the Arm...

  9. Approaching the ideal elastic limit of metallic glasses

    OpenAIRE

    Tian, Lin; Cheng, Yong-Qiang; Shan, Zhi-Wei; Li, Ju; Cheng-cai WANG; Han, Xiao-dong; Sun, Jun; Ma, Evan

    2012-01-01

    The ideal elastic limit is the upper bound to the stress and elastic strain a material can withstand. This intrinsic property has been widely studied for crystalline metals, both theoretically and experimentally. For metallic glasses, however, the ideal elastic limit remains poorly characterized and understood. Here we show that the elastic strain limit and the corresponding strength of submicron-sized metallic glass specimens are about twice as high as the already impressive elastic limit ob...

  10. Aneurysm diameter and proximal aortic neck diameter influence clinical outcome of endovascular abdominal aortic repair : A 4-year EUROSTAR experience

    NARCIS (Netherlands)

    Waasdorp, EJ; de Vries, JPPM; Hobo, R; Leurs, LJ; Buth, J; Moll, FL

    2005-01-01

    Our objective was to evaluate the effect of preoperative aneurysm and aortic neck diameter on clinical outcome after infrarenal abdominal endovascular aneurysm repair (EVAR). Data of patients in the European Collaborators Registry on Stent-Graft Techniques for Abdominal Aortic Aneurysm Repair (EUROS

  11. Effects of an Elastic Hamstring Assistance Device During Downhill Running

    Directory of Open Access Journals (Sweden)

    Aldret Randy L

    2017-06-01

    Full Text Available The purpose of this study was to determine the appropriateness of using an elastic hamstring assistance device to reduce perceived levels of soreness, increase isometric strength, increase passive range of motion, and decrease biomarkers of muscle damage after eccentric exercise, specifically, downhill running This study was conducted in a university exercise physiology laboratory placing sixteen apparently healthy males (X = 21.6 ± 2.5 years into two groups using a pre-test/post-test design. Pre-intervention measures taken included participants’ body height, body mass, body fat, capillary blood samples, VO2max, isometric hamstring strength at 45 and 90 degrees of flexion and passive hamstring range of motion. Post-intervention measures included blood biomarkers, passive range of motion, the perceived level of soreness and isometric strength. An analysis of normality of data was initially conducted followed by multivariate analysis of variance (MANOVA of hamstring strength at 45 and 90 degrees of flexion, blood myoglobin and passive range of motion of the hamstrings. Statistically significant changes were noted in subject-perceived muscle soreness and isometric strength at 90 degrees at the 24-hour post-exercise trial measure between the two groups. Results would suggest the findings could be explained by the decrease in muscle soreness from utilizing the device during the exercise trial. Further research should be conducted to address sample size issues and to determine if the results are comparable on different surfaces.

  12. Effects of an Elastic Hamstring Assistance Device During Downhill Running.

    Science.gov (United States)

    Aldret, Randy L; Trahan, Brittany A; Davis, Greggory; Campbell, Brian; Bellar, David M

    2017-06-01

    The purpose of this study was to determine the appropriateness of using an elastic hamstring assistance device to reduce perceived levels of soreness, increase isometric strength, increase passive range of motion, and decrease biomarkers of muscle damage after eccentric exercise, specifically, downhill running This study was conducted in a university exercise physiology laboratory placing sixteen apparently healthy males (X = 21.6 ± 2.5 years) into two groups using a pre-test/post-test design. Pre-intervention measures taken included participants' body height, body mass, body fat, capillary blood samples, VO2max, isometric hamstring strength at 45 and 90 degrees of flexion and passive hamstring range of motion. Post-intervention measures included blood biomarkers, passive range of motion, the perceived level of soreness and isometric strength. An analysis of normality of data was initially conducted followed by multivariate analysis of variance (MANOVA) of hamstring strength at 45 and 90 degrees of flexion, blood myoglobin and passive range of motion of the hamstrings. Statistically significant changes were noted in subject-perceived muscle soreness and isometric strength at 90 degrees at the 24-hour post-exercise trial measure between the two groups. Results would suggest the findings could be explained by the decrease in muscle soreness from utilizing the device during the exercise trial. Further research should be conducted to address sample size issues and to determine if the results are comparable on different surfaces.

  13. Artificial neural network for modeling the elastic modulus of electrospun polycaprolactone/gelatin scaffolds.

    Science.gov (United States)

    Vatankhah, Elham; Semnani, Dariush; Prabhakaran, Molamma P; Tadayon, Mahdi; Razavi, Shahnaz; Ramakrishna, Seeram

    2014-02-01

    Scaffolds for tissue engineering (TE) require the consideration of multiple aspects, including polymeric composition and the structure and mechanical properties of the scaffolds, in order to mimic the native extracellular matrix of the tissue. Electrospun fibers are frequently utilized in TE due to their tunable physical, chemical, and mechanical properties and porosity. The mechanical properties of electrospun scaffolds made from specific polymers are highly dependent on the processing parameters, which can therefore be tuned for particular applications. Fiber diameter and orientation along with polymeric composition are the major factors that determine the elastic modulus of electrospun nano- and microfibers. Here we have developed a neural network model to investigate the simultaneous effects of composition, fiber diameter and fiber orientation of electrospun polycaprolactone/gelatin mats on the elastic modulus of the scaffolds under ambient and simulated physiological conditions. The model generated might assist bioengineers to fabricate electrospun scaffolds with defined fiber diameters, orientations and constituents, thereby replicating the mechanical properties of the native target tissue.

  14. Acquired disorders of elastic tissue: part I. Increased elastic tissue and solar elastotic syndromes.

    Science.gov (United States)

    Lewis, Kevan G; Bercovitch, Lionel; Dill, Sara W; Robinson-Bostom, Leslie

    2004-07-01

    Elastic fibers in the extracellular matrix are an integral component of dermal connective tissue. The resilience and elasticity required for normal structure and function of the skin may be attributed to the network of elastic tissue. Advances in our understanding of elastic tissue physiology provide a foundation for studying the pathogenesis of elastic tissue disorders. Many acquired disorders are nevertheless poorly understood due to the paucity of reported cases. Several acquired disorders in which accumulation or elastotic degeneration of dermal elastic fibers produces prominent clinical and histopathologic features have recently been described. They include elastoderma, linear focal elastosis, and late-onset focal dermal elastosis and must be differentiated from better-known disorders, among them acquired pseudoxanthoma elasticum, elastosis perforans serpiginosa, and Favré-Racouchot syndrome. Learning objective At the conclusion of this learning activity, participants should understand the similarities and differences between acquired disorders of elastic tissue that are characterized by an increase in elastic tissue, as well as the spectrum of solar elastotic dermatoses.

  15. Enhanced Elastic Modulus of Regenerated Silk Fibroin by Geometric Confinement in Anodized Aluminum Oxide Templates

    Science.gov (United States)

    Li, Jiankang; Li, Liang

    2017-02-01

    Geometric confinement is a promising method for the reconstruction of silk fibroin to form diversified structures with excellent mechanical properties. To accomplish geometric confinement, a water vapor assistant embossing process is used with porous anodic aluminum oxide templates, yielding silk fibroin nanopillars with diameters ranging from 40 nm to 130 nm. The elastic modulus of the regenerated silk fibroin nanopillars is investigated with atomic force microscopy nanoindentation analysis. Compared to films with the same treatment conditions, geometric confinement provided a twofold increase in elastic modulus in embossed silk fibroin nanopillars, indicating that β-sheet crystal ordering occurred during the water vapor assistant embossing process. These results demonstrate the feasibility and mechanical property enhancement of the embossing method to fabricate silk nanostructures, and will be useful in designing miniaturized devices.

  16. Understanding Blood Counts

    Science.gov (United States)

    ... Lab and Imaging Tests Understanding Blood Counts Understanding Blood Counts Understanding Blood Counts SHARE: Print Glossary Blood cell counts give ... your blood that's occupied by red cells. Normal Blood Counts Normal blood counts fall within a range ...

  17. Conical Refraction of Elastic Waves by Anisotropic Metamaterials and Application for Parallel Translation of Elastic Waves.

    Science.gov (United States)

    Ahn, Young Kwan; Lee, Hyung Jin; Kim, Yoon Young

    2017-08-30

    Conical refraction, which is quite well-known in electromagnetic waves, has not been explored well in elastic waves due to the lack of proper natural elastic media. Here, we propose and design a unique anisotropic elastic metamaterial slab that realizes conical refraction for horizontally incident longitudinal or transverse waves; the single-mode wave is split into two oblique coupled longitudinal-shear waves. As an interesting application, we carried out an experiment of parallel translation of an incident elastic wave system through the anisotropic metamaterial slab. The parallel translation can be useful for ultrasonic non-destructive testing of a system hidden by obstacles. While the parallel translation resembles light refraction through a parallel plate without angle deviation between entry and exit beams, this wave behavior cannot be achieved without the engineered metamaterial because an elastic wave incident upon a dissimilar medium is always split at different refraction angles into two different modes, longitudinal and shear.

  18. Magneto-thermo-elastic waves in an infinite perfectly conducting elastic solid with energy dissipation

    Institute of Scientific and Technical Information of China (English)

    Payel Das; Mridula Kanoria

    2009-01-01

    The generalized thermo-elasticity theory, i.e., Green and Naghdi (G-N) III theory, with energy dissipation (TEWED) is employed in the study of time-harmonic plane wave propagation in an unbounded, perfectly electrically conducting elastic medium subject to primary uniform magnetic field. A more general dispersion equation with com-plex coefficients is obtained for coupled magneto-thermo-elastic wave solved in complex domain by using the Leguerre's method. It reveals that the coupled magneto-thermo-elastic wave corresponds to modified dilatational and thermal wave propagation with finite speeds modified by finite thermal wave speeds, thermo-elastic coupling, thermal diffusivity, and the external magnetic field. Numerical results for a copper-like material are presented.

  19. Polarization bandgaps and fluid-like elasticity in fully solid elastic metamaterials

    Science.gov (United States)

    Ma, Guancong; Fu, Caixing; Wang, Guanghao; Del Hougne, Philipp; Christensen, Johan; Lai, Yun; Sheng, Ping

    2016-11-01

    Elastic waves exhibit rich polarization characteristics absent in acoustic and electromagnetic waves. By designing a solid elastic metamaterial based on three-dimensional anisotropic locally resonant units, here we experimentally demonstrate polarization bandgaps together with exotic properties such as `fluid-like' elasticity. We construct elastic rods with unusual vibrational properties, which we denote as `meta-rods'. By measuring the vibrational responses under flexural, longitudinal and torsional excitations, we find that each vibration mode can be selectively suppressed. In particular, we observe in a finite frequency regime that all flexural vibrations are forbidden, whereas longitudinal vibration is allowed--a unique property of fluids. In another case, the torsional vibration can be suppressed significantly. The experimental results are well interpreted by band structure analysis, as well as effective media with indefinite mass density and negative moment of inertia. Our work opens an approach to efficiently separate and control elastic waves of different polarizations in fully solid structures.

  20. The effects of the Trendelenburg position and the Valsalva manoeuvre on internal jugular vein diameter and placement in children

    Science.gov (United States)

    Dincyurek, Gamze Naime; Mogol, Elif Basagan; Turker, Gurkan; Yavascaoglu, Belgin; Gurbet, Alp; Kaya, Fatma Nur; Moustafa, Bachri Ramadan; Yazici, Tolga

    2015-01-01

    INTRODUCTION We compared the effects of various surgical positions, with and without the Valsalva manoeuvre, on the diameter of the right internal jugular vein (RIJV). METHODS We recruited 100 American Society of Anesthesiologists physical status class I patients aged 2–12 years. The patients’ heart rate, blood pressure, peripheral oxygen saturation and end-tidal CO2 pressure were monitored. Induction of anaesthesia was done using 1% propofol 10 mg/mL and fentanyl 2 µg/kg, while maintenance was achieved with 2% sevoflurane in a mixture of 50/50 oxygen and air (administered via a laryngeal mask airway). The RIJV diameter was measured using ultrasonography when the patient was in the supine position. Thereafter, it was measured when the patient was in the supine position + Valsalva, followed by the Trendelenburg, Trendelenburg + Valsalva, reverse Trendelenburg, and reverse Trendelenburg + Valsalva positions. A 15° depression or elevation was applied for the Trendelenburg position, and an airway pressure of 20 cmH2O was applied in the Valsalva manoeuvre. During ultrasonography, the patient’s head was tilted 20° to the left. RESULTS When compared to the mean RIJV diameter in the supine position, the mean RIJV diameter was significantly greater in all positions (p < 0.001) except for the reverse Trendelenburg position. The greatest increase in diameter was observed in the Trendelenburg position with the Valsalva manoeuvre (p < 0.001). CONCLUSION In paediatric patients, the application of the Trendelenburg position with the Valsalva manoeuvre gave the greatest increase in RIJV diameter. The reverse Trendelenburg position had no significant effect on RIJV diameter. PMID:25597750

  1. Impact of twin boundaries on bulk elastic constants: Density-functional theory data for Young׳s modulus of Ag.

    Science.gov (United States)

    Klöffel, Tobias; Bitzek, Erik; Meyer, Bernd

    2015-06-01

    Experimental and theoretical studies on nanowires have reported a size-dependence of the Young׳s modulus in the axial direction, which has been attributed to the increasing influence of surface stresses with decreasing wire diameter. Internal interfaces and their associated interface stresses could lead to similar changes in the elastic properties. In Kobler et al. [1], however, we reported results from atomistic calculations which showed for Ag that twin boundaries have a negligible effect on the Young׳s modulus. Here, we present data of density-functional theory calculations of elastic constants and Young׳s modulus for defect-free bulk Ag as well as for bulk Ag containing dense arrays of twin boundaries. It is shown that rigorous convergence tests are required in order to be able to deduce changes in the elastic properties due to bulk defects in a reliable way.

  2. Athermal nonlinear elastic constants of amorphous solids.

    Science.gov (United States)

    Karmakar, Smarajit; Lerner, Edan; Procaccia, Itamar

    2010-08-01

    We derive expressions for the lowest nonlinear elastic constants of amorphous solids in athermal conditions (up to third order), in terms of the interaction potential between the constituent particles. The effect of these constants cannot be disregarded when amorphous solids undergo instabilities such as plastic flow or fracture in the athermal limit; in such situations the elastic response increases enormously, bringing the system much beyond the linear regime. We demonstrate that the existing theory of thermal nonlinear elastic constants converges to our expressions in the limit of zero temperature. We motivate the calculation by discussing two examples in which these nonlinear elastic constants play a crucial role in the context of elastoplasticity of amorphous solids. The first example is the plasticity-induced memory that is typical to amorphous solids (giving rise to the Bauschinger effect). The second example is how to predict the next plastic event from knowledge of the nonlinear elastic constants. Using the results of our calculations we derive a simple differential equation for the lowest eigenvalue of the Hessian matrix in the external strain near mechanical instabilities; this equation predicts how the eigenvalue vanishes at the mechanical instability and the value of the strain where the mechanical instability takes place.

  3. PARADOX SOLUTION ON ELASTIC WEDGE DISSIMILAR MATERIALS

    Institute of Scientific and Technical Information of China (English)

    姚伟岸; 张兵茹

    2003-01-01

    According to the Hellinger-Reissner variational principle and introducing proper transformation of variables, the problem on elastic wedge dissimilar materials can be led to Hamiltonian system, so the solution of the problem can be got by employing the separation of variables method and symplectic eigenfunction expansion under symplectic space, which consists of original variables and their dual variables. The eigenvalue - 1 is a special one of all symplectic eigenvalue for Hamiltonian system in polar coordinate. In general, the eigenvalue - is a single eigenvalue, and the classical solution of an elastic wedge dissimilar materials subjected to a unit concentrated couple at the vertex is got directly by solving the eigenfunction vector for eigenvalue - 1 . But the eigenvalue - 1 becomes a double eigenvalue when the vertex angles and modulus of the materials satisfy certain definite relationships and the classical solution for the stress distribution becomes infinite at this moment, that is, the paradox should occur. Here the Jordan form eigenfunction vector for eigenvalue - 1 exists, and solution of the paradox on elastic wedge dissimilar materials subjected to a unit concentrated couple at the vertex is obtained directly by solving this special Jordan form eigenfunction. The result shows again that the solutions of the special paradox on elastic wedge in the classical theory of elasticity are just Jordan form solutions in symplectic space under Hamiltonian system.

  4. Probing hysteretic elasticity in weakly nonlinear materials

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Paul A [Los Alamos National Laboratory; Haupert, Sylvain [UPMC UNIV PARIS; Renaud, Guillaume [UPMC UNIV PARIS; Riviere, Jacques [UPMC UNIV PARIS; Talmant, Maryline [UPMC UNIV PARIS; Laugier, Pascal [UPMC UNIV PARIS

    2010-12-07

    Our work is aimed at assessing the elastic and dissipative hysteretic nonlinear parameters' repeatability (precision) using several classes of materials with weak, intermediate and high nonlinear properties. In this contribution, we describe an optimized Nonlinear Resonant Ultrasound Spectroscopy (NRUS) measuring and data processing protocol applied to small samples. The protocol is used to eliminate the effects of environmental condition changes that take place during an experiment, and that may mask the intrinsic elastic nonlinearity. As an example, in our experiments, we identified external temperature fluctuation as a primary source of material resonance frequency and elastic modulus variation. A variation of 0.1 C produced a frequency variation of 0.01 %, which is similar to the expected nonlinear frequency shift for weakly nonlinear materials. In order to eliminate environmental effects, the variation in f{sub 0} (the elastically linear resonance frequency proportional to modulus) is fit with the appropriate function, and that function is used to correct the NRUS calculation of nonlinear parameters. With our correction procedure, we measured relative resonant frequency shifts of 10{sup -5} , which are below 10{sup -4}, often considered the limit to NRUS sensitivity under common experimental conditions. Our results show that the procedure is an alternative to the stringent control of temperature often applied. Applying the approach, we report nonlinear parameters for several materials, some with very small nonclassical nonlinearity. The approach has broad application to NRUS and other Nonlinear Elastic Wave Spectroscopy approaches.

  5. Continuously-variable series-elastic actuator.

    Science.gov (United States)

    Mooney, Luke; Herr, Hugh

    2013-06-01

    Actuator efficiency is an important factor in the design of powered leg prostheses, orthoses, exoskeletons, and legged robots. A continuously-variable series-elastic actuator (CV-SEA) is presented as an efficient actuator for legged locomotion. The CV-SEA implements a continuously-variable transmission (CVT) between a motor and series elastic element. The CVT reduces the torque seen at the motor and allows the motor to operate in speed regimes of higher efficiency, while the series-elastic element efficiently stores and releases mechanical energy, reducing motor work requirements for actuator applications where an elastic response is sought. An energy efficient control strategy for the CV-SEA was developed using a Monte-Carlo minimization method that randomly generates transmission profiles and converges on those that minimize the electrical energy consumption of the motor. The CV-SEA is compared to a standard SEA and an infinitely variable series elastic actuator (IV-SEA). Simulations suggest that a CV-SEA will require less energy that an SEA or IV-SEA when used in a knee prosthesis during level-ground walking.

  6. The Elastic Constants for Wrought Aluminum Alloys

    Science.gov (United States)

    Templin, R L; Hartmann, E C

    1945-01-01

    There are several constants which have been devised as numerical representations of the behavior of metals under the action of loadings which stress the metal within the range of elastic action. Some of these constants, such as Young's modulus of elasticity in tension and compression, shearing modulus of elasticity, and Poisson's ratio, are regularly used in engineering calculations. Precise tests and experience indicate that these elastic constants are practically unaffected by many of the factors which influence the other mechanical properties of materials and that a few careful determinations under properly controlled conditions are more useful and reliable than many determinations made under less favorable conditions. It is the purpose of this paper to outline the methods employed by the Aluminum Research Laboratories for the determination of some of these elastic constants, to list the values that have been determined for some of the wrought aluminum alloys, and to indicate the variations in the values that may be expected for some of the commercial products of these alloys.

  7. Blood donation

    CERN Multimedia

    GS Department

    2009-01-01

    A blood donation is organised by the Cantonal Hospital of Geneva On Thursday 19 March 2009 from 9 a.m. to 5 p.m. CERN RESTAURANT 2 Number of donations during the last blood donations :135 donors in July 2008 122 donors in November 2008 Let’s do better in 2009 !!! Give 30 minutes of your time to save lives...

  8. Artificial Blood

    Directory of Open Access Journals (Sweden)

    Umit Yasar

    2012-04-01

    Full Text Available The problems and additional cost factor involved in collecting and storing human blood, as well as the pending worldwide shortages are the main driving forces in the development of blood substitutes. Studies on artificial blood basically aim to develop oxygen carrying compounds, produce stem cell-based erythrocyte cells in vitro and, implement the functions and movements of natural hemoglobin molecules found in erythrocyte cells through artificial erythrocyte cells. Consequently, major areas of research in artificial blood studies are haemoglobin-based oxygen carriers, perfluorochemicals, respirocytes and stem cells. Even though these artificial erythrocyte cells do not qualify as perfect red blood cell substitutes yet, they have many potential clinical and non clinical uses. Studies are being carried out on the elimination of side effects of blood substitutes and extensive clinical trials are being conducted to test their safety and efficacy. Artificial blood substitutes could only be used clinically for patient management following clinical trials and approvals, and will be the ultimate global solution to the problems associated with donor scarcity, blood collection and transfusion-mediated diseases. [Archives Medical Review Journal 2012; 21(2.000: 95-108

  9. BLOOD DONATION

    CERN Multimedia

    SC Unit

    2008-01-01

    A blood donation, organized by EFS (Etablissement Français du Sang) of Annemasse will take place On Wednesday 12 November 2008, from 8:30 to 16:00, at CERN Restaurant 2 If possible, please, bring your blood group Card.

  10. Blood flow

    Science.gov (United States)

    ... the same time, the veins carry oxygen-poor blood (shown in blue) from the tissues back toward the heart. From there, it passes to the lungs to receive more oxygen. This cycle repeats itself when oxygen-rich blood returns to the heart from the lungs, which ...

  11. BLOOD DONATION

    CERN Multimedia

    SC Unit

    2008-01-01

    A blood donation, organized by EFS (Etablissement Français du Sang) of Annemasse will take place On Wednesday 12 November 2008, from 8:30 to 16:00, at CERN Restaurant 2 If possible, please, bring your blood group Card.

  12. Tunable diameter electrostatically formed nanowire for high sensitivity gas sensing

    Institute of Scientific and Technical Information of China (English)

    Alex Henning; Nandhini Swaminathan; Andrey Godkin; Gil Shalev; Iddo Amit; Yossi Rosenwaks

    2015-01-01

    We report on an electrostatically formed nanowire (EFN)-based sensor with tunable diameters in the range of 16 nm to 46 nm and demonstrate an EFN- based field-effect transistor as a highly sensitive and robust room temperature gas sensor. The device was carefully designed and fabricated using standard integrated processing to achieve the 16 nm EFN that can be used for sensing without any need for surface modification. The effective diameter for the EFN was determined using Kelvin probe force microscopy accompanied by three- dimensional electrostatic simulations. We show that the EFN transistor is capable of detecting 100 parts per million of ethanol gas with bare SiO2.

  13. Angular diameter distances reconsidered in the Newman and Penrose formalism

    CERN Document Server

    Kling, Thomas P

    2016-01-01

    Using the Newman and Penrose spin coefficient (NP) formalism, we provide a derivation of the Dyer-Roeder equation for the angular diameter distance in cosmological space-times. We show that the geodesic deviation equation written in NP formalism is precisely the Dyer-Roeder equation for a general Friedman-Robertson-Walker (FRW) space-time, and then we examine the angular diameter distance to redshift relation in the case that a flat FRW metric is perturbed by a gravitational potential. We examine the perturbation in the case that the gravitational potential exhibits the properties of a thin gravitational lens, demonstrating how the weak lensing shear and convergence act as source terms for the perturbed Dyer-Roeder equation.

  14. Tainted blood

    DEFF Research Database (Denmark)

    Deleuran, Ida; Sheikh, Zainab Afshan; Hoeyer, Klaus

    2015-01-01

    study of the historical rise and current workings of safety practices in the Danish blood system. Here, we identify a strong focus on contamination in order to avoid 'tainted blood', at the expense of working with risks that could be avoided through enhanced blood monitoring practices. Of further...... significance to this focus are the social dynamics found at the heart of safety practices aimed at avoiding contamination. We argue that such dynamics need more attention, in order to achieve good health outcomes in transfusion medicine. Thus, we conclude that, to ensure continuously safe blood systems, we...... need to move beyond the bifurcation of the social and medical aspects of blood supply as two separate issues and approach social dynamics as key medical safety questions....

  15. Consequences of the Continuity of the Monic Integer Transfinite Diameter

    CERN Document Server

    Hilmar, Jan

    2007-01-01

    We consider the problem of determining the monic integer transfinite diameter t_M(I)&=&\\lim_{n\\to\\infty}\\inf_{p_n\\in{\\mathcal M_n}}\\supnorm{p_n}{I}^{1/n} for real intervals of length less than 4. We show the $t_M([0,x])$, as a function in $x>0$, is continuous, therefore disproving two conjectures due to Hare and Smyth. Consequently, for $n>2\\in\

  16. A study of the heated length to diameter effects

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong Ho; Baek, Won Pil; Chang, Soon Heung [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1997-12-31

    An analytical and experimental investigation has been performed on the heated length-to-diameter effect on critical heat flux exit conditions. A L/D correction factor is developed by applying artificial neural network and conventional regression techniques to the KAIST CHF data base. In addition, experiment is being performed to validate the developed L/D correction factor with independent data. Assessment shows that the developed correction factor is promising for practical applications. 6 refs., 8 figs. (Author)

  17. Uncertainty budget for optical coordinate measurements of circle diameter

    DEFF Research Database (Denmark)

    Morace, Renate Erica; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2004-01-01

    An uncertainty analysis for circle diameter measurements using a coordinate measuring machine (CMM) equipped with an optical probe is presented in this paper. A mathematical model for data evaluation and uncertainty assessment was formulated in accordance with Guide to the Expression of Uncertainty...... in Measurement (GUM). Various input quantities such as CCD camera resolution, influence of illuminating system, CMM errors etc. were considered in the model function and experimentally investigated....

  18. Pupil Center as a Function of Pupil Diameter

    DEFF Research Database (Denmark)

    Ahmed, Zaheer; Mardanbegi, Diako; Hansen, Dan Witzner

    2016-01-01

    We investigate the gaze estimation error induced by pupil size changes using simulated data. We investigate the influence of pupil diameter changes on estimated gaze point error obtained by two gaze estimation models. Simulation data show that at wider viewing angles and at small eye......-camera distances, error increases with increasing pupil sizes. The maximum error recorded for refracted pupil images is 2.4° of visual angle and 1.5° for non-refracted pupil projections....

  19. THE CUTWIDTH OF TREES WITH DIAMETER AT MOST 4

    Institute of Scientific and Technical Information of China (English)

    LinYixun

    2003-01-01

    The cutwidth problem for a graph G is to embed G into a path Pn such that the maximum number of overlap edges (i. e. , the congestion) is minimized. It is known that the problem for general graphs is NP-hard while it is polynomially solvable for trees. This paper presents an exact formula for the cutwidth of trees with diameter at most 4. A relation with the bandwidth is discussed as well.

  20. PREPARATION AND ADSORBABILITY OF DEXTRAN MICROSPHERES WITH UNIFORM DIAMETER

    Institute of Scientific and Technical Information of China (English)

    Ri-sheng Yao; Wen-xia Gao; Jing Sun; Ya-hua You

    2005-01-01

    The method of preparing uniform dextran microspheres with a narrow diameter distribution was introduced and the adsorbability of these microspheres was evaluated. The microspheres were prepared in W/O microemulsion using 0.5% dextran solution as the aqueous phase and n-hexane as the oil phase. Characteristics of the prepared dextran microspheres were examined with laser light blocking technique, optical microscope and ultraviolet spectrometer. The results show that the prepared dextran microspheres have uniform morphology and narrow diameter distribution, nearly 92% of them having a diameter of 56.6 μm. In vitro evaluation of adsorbability, wet dextran microspheres have good adsorption of 98.32 mg/g of model drug methylene blue in 20.86 mg/L methylene blue solution at 25℃. The adsorption of dried dextran microspheres under the same condition is 132.15 mg/g, which is even higher. And the adsorbability of dextran microspheres has significant relationship with the concentration of methylene blue and temperature. The adsorbability is better at lower temperature and higher concentration of methylene blue.