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Sample records for 3-dimensional traction forces

  1. Modeling traction forces in collective cell migration

    NASA Astrophysics Data System (ADS)

    Zimmermann, Juliane; Basan, Markus; Hayes, Ryan L.; Rappel, Wouter-Jan; Levine, Herbert

    2015-03-01

    Collective cell migration is an important process in embryonic development, wound healing, and cancer metastasis. We have developed a particle-based simulation for collective cell migration that describes flow patterns and finger formation at the tissue edge observed in wound healing experiments. We can apply methods for calculating intercellular stress to our simulation model, and have thereby provided evidence for the validity of a stress reconstitution method from traction forces used in experiments. To accurately capture experimentally measured traction forces and stresses in the tissue, which are mostly tensile, we have to include intracellular acto-myosin contraction into our simulation. We can then reproduce the experimentally observed behavior of cells moving around a circular obstacle, and suggest underlying mechanisms for cell-cell alignment and generation of traction force patterns.

  2. Flow mechanotransduction regulates traction forces, intercellular forces, and adherens junctions

    PubMed Central

    Ting, Lucas H.; Jahn, Jessica R.; Jung, Joon I.; Shuman, Benjamin R.; Feghhi, Shirin; Han, Sangyoon J.; Rodriguez, Marita L.

    2012-01-01

    Endothelial cells respond to fluid shear stress through mechanotransduction responses that affect their cytoskeleton and cell-cell contacts. Here, endothelial cells were grown as monolayers on arrays of microposts and exposed to laminar or disturbed flow to examine the relationship among traction forces, intercellular forces, and cell-cell junctions. Cells under laminar flow had traction forces that were higher than those under static conditions, whereas cells under disturbed flow had lower traction forces. The response in adhesion junction assembly matched closely with changes in traction forces since adherens junctions were larger in size for laminar flow and smaller for disturbed flow. Treating the cells with calyculin-A to increase myosin phosphorylation and traction forces caused an increase in adherens junction size, whereas Y-27362 cause a decrease in their size. Since tugging forces across cell-cell junctions can promote junctional assembly, we developed a novel approach to measure intercellular forces and found that these forces were higher for laminar flow than for static or disturbed flow. The size of adherens junctions and tight junctions matched closely with intercellular forces for these flow conditions. These results indicate that laminar flow can increase cytoskeletal tension while disturbed flow decreases cytoskeletal tension. Consequently, we found that changes in cytoskeletal tension in response to shear flow conditions can affect intercellular tension, which in turn regulates the assembly of cell-cell junctions. PMID:22447948

  3. Super-Resolved Traction Force Microscopy (STFM)

    PubMed Central

    2016-01-01

    Measuring small forces is a major challenge in cell biology. Here we improve the spatial resolution and accuracy of force reconstruction of the well-established technique of traction force microscopy (TFM) using STED microscopy. The increased spatial resolution of STED-TFM (STFM) allows a greater than 5-fold higher sampling of the forces generated by the cell than conventional TFM, accessing the nano instead of the micron scale. This improvement is highlighted by computer simulations and an activating RBL cell model system. PMID:26923775

  4. Super-Resolved Traction Force Microscopy (STFM).

    PubMed

    Colin-York, Huw; Shrestha, Dilip; Felce, James H; Waithe, Dominic; Moeendarbary, Emad; Davis, Simon J; Eggeling, Christian; Fritzsche, Marco

    2016-04-13

    Measuring small forces is a major challenge in cell biology. Here we improve the spatial resolution and accuracy of force reconstruction of the well-established technique of traction force microscopy (TFM) using STED microscopy. The increased spatial resolution of STED-TFM (STFM) allows a greater than 5-fold higher sampling of the forces generated by the cell than conventional TFM, accessing the nano instead of the micron scale. This improvement is highlighted by computer simulations and an activating RBL cell model system. PMID:26923775

  5. Micropatterning tractional forces in living cells

    NASA Technical Reports Server (NTRS)

    Wang, Ning; Ostuni, Emanuele; Whitesides, George M.; Ingber, Donald E.

    2002-01-01

    Here we describe a method for quantifying traction in cells that are physically constrained within micron-sized adhesive islands of defined shape and size on the surface of flexible polyacrylamide gels that contain fluorescent microbeads (0.2-microm diameter). Smooth muscle cells were plated onto square (50 x 50 microm) or circular (25- or 50-microm diameter) adhesive islands that were created on the surface of the gels by applying a collagen coating through microengineered holes in an elastomeric membrane that was later removed. Adherent cells spread to take on the size and shape of the islands and cell tractions were quantitated by mapping displacement fields of the fluorescent microbeads within the gel. Cells on round islands did not exhibit any preferential direction of force application, but they exerted their strongest traction at sites where they formed protrusions. When cells were confined to squares, traction was highest in the corners both in the absence and presence of the contractile agonist, histamine, and cell protrusions were also observed in these regions. Quantitation of the mean traction exerted by cells cultured on the different islands revealed that cell tension increased as cell spreading was promoted. These results provide a mechanical basis for past studies that demonstrated a similar correlation between spreading and growth within various anchorage-dependent cells. This new approach for analyzing the spatial distribution of mechanical forces beneath individual cells that are experimentally constrained to defined sizes and shapes may provide additional insight into the biophysical basis of cell regulation. Copyright 2002 Wiley-Liss, Inc.

  6. Intercellular Stress Reconstitution from Traction Force Data

    PubMed Central

    Zimmermann, Juliane; Hayes, Ryan L.; Basan, Markus; Onuchic, José N.; Rappel, Wouter-Jan; Levine, Herbert

    2014-01-01

    Cells migrate collectively during development, wound healing, and cancer metastasis. Recently, a method has been developed to recover intercellular stress in monolayers from measured traction forces upon the substrate. To calculate stress maps in two dimensions, the cell sheet was assumed to behave like an elastic material, and it remains unclear to what extent this assumption is valid. In this study, we simulate our recently developed model for collective cell migration, and compute intercellular stress maps using the method employed in the experiments. We also compute these maps using a method that does not depend on the traction forces or material properties. The two independently obtained stress patterns agree well for the parameters we have probed and provide a verification of the validity of the experimental method. PMID:25099794

  7. High-Resolution Traction Force Microscopy

    PubMed Central

    Plotnikov, Sergey V.; Sabass, Benedikt; Schwarz, Ulrich S.; Waterman, Clare M.

    2015-01-01

    Cellular forces generated by the actomyosin cytoskeleton and transmitted to the extracellular matrix (ECM) through discrete, integrin-based protein assemblies, that is, focal adhesions, are critical to developmental morphogenesis and tissue homeostasis, as well as disease progression in cancer. However, quantitative mapping of these forces has been difficult since there has been no experimental technique to visualize nanonewton forces at submicrometer spatial resolution. Here, we provide detailed protocols for measuring cellular forces exerted on two-dimensional elastic substrates with a high-resolution traction force microscopy (TFM) method. We describe fabrication of polyacrylamide substrates labeled with multiple colors of fiducial markers, functionalization of the substrates with ECM proteins, setting up the experiment, and imaging procedures. In addition, we provide the theoretical background of traction reconstruction and experimental considerations important to design a high-resolution TFM experiment. We describe the implementation of a new algorithm for processing of images of fiducial markers that are taken below the surface of the substrate, which significantly improves data quality. We demonstrate the application of the algorithm and explain how to choose a regularization parameter for suppression of the measurement error. A brief discussion of different ways to visualize and analyze the results serves to illustrate possible uses of high-resolution TFM in biomedical research. PMID:24974038

  8. Keratocytes generate traction forces in two phases.

    PubMed

    Burton, K; Park, J H; Taylor, D L

    1999-11-01

    Forces generated by goldfish keratocytes and Swiss 3T3 fibroblasts have been measured with nanonewton precision and submicrometer spatial resolution. Differential interference contrast microscopy was used to visualize deformations produced by traction forces in elastic substrata, and interference reflection microscopy revealed sites of cell-substratum adhesions. Force ranged from a few nanonewtons at submicrometer spots under the lamellipodium to several hundred nanonewtons under the cell body. As cells moved forward, centripetal forces were applied by lamellipodia at sites that remained stationary on the substratum. Force increased and abruptly became lateral at the boundary of the lamellipodium and the cell body. When the cell retracted at its posterior margin, cell-substratum contact area decreased more rapidly than force, so that stress (force divided by area) increased as the cell pulled away. An increase in lateral force was associated with widening of the cell body. These mechanical data suggest an integrated, two-phase mechanism of cell motility: (1) low forces in the lamellipodium are applied in the direction of cortical flow and cause the cell body to be pulled forward; and (2) a component of force at the flanks pulls the rear margins forward toward the advancing cell body, whereas a large lateral component contributes to detachment of adhesions without greatly perturbing forward movement. PMID:10564269

  9. Traction forces at solid-lubricated rolling/sliding contacts

    NASA Technical Reports Server (NTRS)

    Aggarwal, B. B.; Bovenkerk, R. L.

    1985-01-01

    A single-element traction rig was used to measure the traction forces at a solid-lubricated contact of a ball against a flat disk at room temperature under combine rolling and sliding. The load and speed conditions were selected to match those anticipated for bearing applications in adiabatic diesel engines. Traction vs slide/roll ratio curves were similar to those for liquid lubricants but the traction forces were an order of magnitude higher. The test data were used to derive equations to predict traction force as a function of contact stress and rolling speed. The data showed that the magnitude of traction forces were almost the same for all the lubricants tested. The lubricants, should, therefore, be selected on the basis of their ability to limit the wear of contact surfaces.

  10. Traction force dynamics predict gap formation in activated endothelium.

    PubMed

    Valent, Erik T; van Nieuw Amerongen, Geerten P; van Hinsbergh, Victor W M; Hordijk, Peter L

    2016-09-10

    In many pathological conditions the endothelium becomes activated and dysfunctional, resulting in hyperpermeability and plasma leakage. No specific therapies are available yet to control endothelial barrier function, which is regulated by inter-endothelial junctions and the generation of acto-myosin-based contractile forces in the context of cell-cell and cell-matrix interactions. However, the spatiotemporal distribution and stimulus-induced reorganization of these integral forces remain largely unknown. Traction force microscopy of human endothelial monolayers was used to visualize contractile forces in resting cells and during thrombin-induced hyperpermeability. Simultaneously, information about endothelial monolayer integrity, adherens junctions and cytoskeletal proteins (F-actin) were captured. This revealed a heterogeneous distribution of traction forces, with nuclear areas showing lower and cell-cell junctions higher traction forces than the whole-monolayer average. Moreover, junctional forces were asymmetrically distributed among neighboring cells. Force vector orientation analysis showed a good correlation with the alignment of F-actin and revealed contractile forces in newly formed filopodia and lamellipodia-like protrusions within the monolayer. Finally, unstable areas, showing high force fluctuations within the monolayer were prone to form inter-endothelial gaps upon stimulation with thrombin. To conclude, contractile traction forces are heterogeneously distributed within endothelial monolayers and force instability, rather than force magnitude, predicts the stimulus-induced formation of intercellular gaps. PMID:27498166

  11. Changes in cervical muscle activity according to the traction force of an air-inflatable neck traction device.

    PubMed

    Kang, Jong Ho; Park, Tae-Sung

    2015-09-01

    [Purpose] The purpose of this study was to analyze cervical muscle activity at different traction forces of an air-inflatable neck traction device. [Subjects] Eighteen males participated in this study. [Methods] The subjects put on an air-inflatable neck traction device and the traction forces administered were 40, 80, and 120 mmHg. The electromyography (EMG) signals of the splenius capitis, and upper trapezius were measured to assess the muscle activity. [Results] The muscle activity of the splenius capitis was significantly higher at 80, and 120 mmHg compared to 40 mmHg. The muscle activity of the upper trapezius did not show significant differences among the traction forces. [Conclusion] Our research result showed that the air-inflatable home neck traction device did not meet the condition of muscle relaxation. PMID:26504278

  12. Changes in cervical muscle activity according to the traction force of an air-inflatable neck traction device

    PubMed Central

    Kang, Jong Ho; Park, Tae-Sung

    2015-01-01

    [Purpose] The purpose of this study was to analyze cervical muscle activity at different traction forces of an air-inflatable neck traction device. [Subjects] Eighteen males participated in this study. [Methods] The subjects put on an air-inflatable neck traction device and the traction forces administered were 40, 80, and 120 mmHg. The electromyography (EMG) signals of the splenius capitis, and upper trapezius were measured to assess the muscle activity. [Results] The muscle activity of the splenius capitis was significantly higher at 80, and 120 mmHg compared to 40 mmHg. The muscle activity of the upper trapezius did not show significant differences among the traction forces. [Conclusion] Our research result showed that the air-inflatable home neck traction device did not meet the condition of muscle relaxation. PMID:26504278

  13. Modeling cell-matrix traction forces in Keratinocyte colonies

    NASA Astrophysics Data System (ADS)

    Banerjee, Shiladitya

    2013-03-01

    Crosstalk between cell-cell and cell-matrix adhesions plays an essential role in the mechanical function of tissues. The traction forces exerted by cohesive keratinocyte colonies with strong cell-cell adhesions are mostly concentrated at the colony periphery. In contrast, for weak cadherin-based intercellular adhesions, individual cells in a colony interact with their matrix independently, with a disorganized distribution of traction forces extending throughout the colony. In this talk I will present a minimal physical model of the colony as contractile elastic media linked by springs and coupled to an elastic substrate. The model captures the spatial distribution of traction forces seen in experiments. For cell colonies with strong cell-cell adhesions, the total traction force of the colony measured in experiments is found to scale with the colony's geometrical size. This scaling suggests the emergence of an effective surface tension of magnitude comparable to that measured for non-adherent, three-dimensional cell aggregates. The physical model supports the scaling and indicates that the surface tension may be controlled by acto-myosin contractility. Supported by the NSF through grant DMR-1004789. This work was done in collaboration with Aaron F. Mertz, Eric R. Dufresne and Valerie Horsley (Yale University) and M. Cristina Marchetti (Syracuse University).

  14. High Resolution, Large Deformation 3D Traction Force Microscopy

    PubMed Central

    López-Fagundo, Cristina; Reichner, Jonathan; Hoffman-Kim, Diane; Franck, Christian

    2014-01-01

    Traction Force Microscopy (TFM) is a powerful approach for quantifying cell-material interactions that over the last two decades has contributed significantly to our understanding of cellular mechanosensing and mechanotransduction. In addition, recent advances in three-dimensional (3D) imaging and traction force analysis (3D TFM) have highlighted the significance of the third dimension in influencing various cellular processes. Yet irrespective of dimensionality, almost all TFM approaches have relied on a linear elastic theory framework to calculate cell surface tractions. Here we present a new high resolution 3D TFM algorithm which utilizes a large deformation formulation to quantify cellular displacement fields with unprecedented resolution. The results feature some of the first experimental evidence that cells are indeed capable of exerting large material deformations, which require the formulation of a new theoretical TFM framework to accurately calculate the traction forces. Based on our previous 3D TFM technique, we reformulate our approach to accurately account for large material deformation and quantitatively contrast and compare both linear and large deformation frameworks as a function of the applied cell deformation. Particular attention is paid in estimating the accuracy penalty associated with utilizing a traditional linear elastic approach in the presence of large deformation gradients. PMID:24740435

  15. Microglia mechanics: immune activation alters traction forces and durotaxis

    PubMed Central

    Bollmann, Lars; Koser, David E.; Shahapure, Rajesh; Gautier, Hélène O. B.; Holzapfel, Gerhard A.; Scarcelli, Giuliano; Gather, Malte C.; Ulbricht, Elke; Franze, Kristian

    2015-01-01

    Microglial cells are key players in the primary immune response of the central nervous system. They are highly active and motile cells that chemically and mechanically interact with their environment. While the impact of chemical signaling on microglia function has been studied in much detail, the current understanding of mechanical signaling is very limited. When cultured on compliant substrates, primary microglial cells adapted their spread area, morphology, and actin cytoskeleton to the stiffness of their environment. Traction force microscopy revealed that forces exerted by microglia increase with substrate stiffness until reaching a plateau at a shear modulus of ~5 kPa. When cultured on substrates incorporating stiffness gradients, microglia preferentially migrated toward stiffer regions, a process termed durotaxis. Lipopolysaccharide-induced immune-activation of microglia led to changes in traction forces, increased migration velocities and an amplification of durotaxis. We finally developed a mathematical model connecting traction forces with the durotactic behavior of migrating microglial cells. Our results demonstrate that microglia are susceptible to mechanical signals, which could be important during central nervous system development and pathologies. Stiffness gradients in tissue surrounding neural implants such as electrodes, for example, could mechanically attract microglial cells, thus facilitating foreign body reactions detrimental to electrode functioning. PMID:26441534

  16. Traction force and tension fluctuations in growing axons

    PubMed Central

    Polackwich, Robert J.; Koch, Daniel; McAllister, Ryan; Geller, Herbert M.; Urbach, Jeffrey S.

    2015-01-01

    Actively generated mechanical forces play a central role in axon growth and guidance, but the mechanisms that underly force generation and regulation in growing axons remain poorly understood. We report measurements of the dynamics of traction stresses from growth cones of actively advancing axons from postnatal rat DRG neurons. By tracking the movement of the growth cone and analyzing the traction stress field from a reference frame that moves with it, we are able to show that there is a clear and consistent average stress field that underlies the complex spatial stresses present at any one time. The average stress field has strong maxima on the sides of the growth cone, directed inward toward the growth cone neck. This pattern represents a contractile stress contained within the growth cone, and a net force that is balanced by the axon tension. Using high time-resolution measurements of the growth cone traction stresses, we show that the stress field is composed of fluctuating local stress peaks, with a large number peaks that live for a short time, a population of peaks whose lifetime distribution follows an exponential decay, and a small number of very long-lived peaks. We show that the high time-resolution data also reveal that the tension appears to vary randomly over short time scales, roughly consistent with the lifetime of the stress peaks, suggesting that the tension fluctuations originate from stochastic adhesion dynamics. PMID:26578882

  17. Traction force and tension fluctuations in growing axons

    NASA Astrophysics Data System (ADS)

    Urbach, Jeffrey; Polackwich, Jamie; Koch, Daniel; McAllister, Ryan; Geller, Herbert

    Actively generated mechanical forces play a central role in axon growth and guidance during nervous system development. We describe the dynamics of traction stresses from growth cones of actively advancing axons from postnatal rat DRG neurons. By tracking the movement of the growth cone and analyzing the traction stresses in a co-moving reference frame, we show that there is a clear and consistent average stress field underlying the complex spatial stresses present at any one time. The average stress field has strong maxima on the sides of the growth cone, directed inward toward the growth cone neck. This pattern represents a Contractile stress contained within the growth cone, and a net force that is balanced by the axon tension. In addition, using high time-resolution measurements, we show that the stress field is composed of fluctuating local stress peaks, with a population of peaks whose lifetime distribution follows an exponential decay, and a small number of very long-lived peaks. We also find that the tension appears to vary randomly over short time scales, roughly consistent with the lifetime of the stress peaks, suggesting that the tension fluctuations originate from stochastic adhesion dynamics.

  18. Human small intestinal contractions and aboral traction forces during fasting and after feeding.

    PubMed Central

    Ahluwalia, N K; Thompson, D G; Barlow, J; Heggie, L

    1994-01-01

    Small intestinal intraluminal pressure activity and aboral traction forces were explored in 19 healthy volunteers using a combined manometry and traction force detecting assembly sited in the upper small intestine. Each aboral traction event was classified as being associated with either a propagating or a stationary contraction and its force measured. During phase I no contractions or traction events were seen. During phase II, traction events related to propagating contractions mean (SEM) (2.2 (0.2)/min) and to stationary contractions (0.3 (0.1)/min) generated similar force/event (7.5(0.9 g v 8.7 (1.4) g, p > 0.05). During phase III, all traction events were related to propagating contractions and generated 9.3 (2.4) g force/event (p > 0.05 v phase II). After feeding, traction events related to propagating contractions generated similar force/event to those related to stationary contractions (5.9 (1.0) g v 9.3 (2.7) g, p > 0.05 v each other and v fasting). No consistent pattern was seen in the temporal distribution of the traction events or in the pattern of the amplitude of the force of successive traction events. PMID:8200554

  19. Traction-drive force transmission for telerobotic joints

    NASA Technical Reports Server (NTRS)

    Kuban, D. P.; Williams, D. M.

    1989-01-01

    The U.S. Space Station Program is providing many technological developments to meet the increasing demands of designing such a facility. One of the key areas of research is that of telerobotics for space station assembly and maintenance. Initial implementation will be teleoperated, but long-term plans call for autonomous robotics. One of the essential components for making this transition successful is the manipulator joints mechanism. Historically, teleoperated manipulators and industrial robotics have had very different mechanisms for force transmission. This is because the design objectives are almost mutually exclusive. A teleoperator must have very low friction and inertia to minimize operator fatigue; backlash and stiffness are of secondary concern. A robot, however, must have minimum backlash, and high stiffness for accurate and rapid positioning. A joint mechanism has yet to be developed that can optimize these divergent performance objectives. A joint mechanism that approaches this optimal performance was developed for NASA Langley, Automation Technology Branch. It is a traction-drive differential that uses variable preload mechanisms. The differential provides compact, dexterous motion range with a torque density similar to geared systems. The traction drive offers high stiffness and zero backlash, for good robotic performance, and the variable loading mechanism (VLM) minimizes the drive-train friction, for improved teleoperation.

  20. Applications of Traction Force Microscopy in Measuring Adhesion Molecule Dependent Cell Contractility

    ERIC Educational Resources Information Center

    Mann, Cynthia Marie

    2009-01-01

    This work describes the use of polyacrylamide hydrogels as controlled elastic modulus substrates for single cell traction force microscopy studies. The first section describes the use of EDC/NHS chemistry to convalently link microbeads to the hydrogel matrix for the purpose of performing long-term traction force studies (7 days). The final study…

  1. Matrix identity and tractional forces influence indirect cardiac reprogramming

    PubMed Central

    Kong, Yen P.; Carrion, Bita; Singh, Rahul K.; Putnam, Andrew J.

    2013-01-01

    Heart regeneration through in vivo cardiac reprogramming has been demonstrated as a possible regenerative strategy. While it has been reported that cardiac reprogramming in vivo is more efficient than in vitro, the influence of the extracellular microenvironment on cardiac reprogramming remains incompletely understood. This understanding is necessary to improve the efficiency of cardiac reprogramming in order to implement this strategy successfully. Here we have identified matrix identity and cell-generated tractional forces as key determinants of the dedifferentiation and differentiation stages during reprogramming. Cell proliferation, matrix mechanics, and matrix microstructure are also important, but play lesser roles. Our results suggest that the extracellular microenvironment can be optimized to enhance cardiac reprogramming. PMID:24326998

  2. Shape and Area of Keratocytes Are Related to the Distribution and Magnitude of Their Traction Forces.

    PubMed

    Sonoda, Ayane; Okimura, Chika; Iwadate, Yoshiaki

    2016-03-26

    Fish epidermal keratocytes maintain an overall fan shape during their crawling migration. The shape-determination mechanism has been described theoretically and experimentally on the basis of graded radial extension of the leading edge, but the relationship between shape and traction forces has not been clarified. Migrating keratocytes can be divided into fragments by treatment with the protein kinase inhibitor staurosporine. Fragments containing a nucleus and cytoplasm behave as mini-keratocytes and maintain the same fan shape as the original cells. We measured the shape of the leading edge, together with the areas of the ventral region and traction forces, of keratocytes and mini-keratocytes. The shapes of keratocytes and mini-keratocytes were similar. Mini-keratocytes exerted traction forces at the rear left and right ends, just like keratocytes. The magnitude of the traction forces was proportional to the area of the keratocytes and mini-keratocytes. The myosin II ATPase inhibitor blebbistatin decreased the forces at the rear left and right ends of the keratocytes and expanded their shape laterally. These results suggest that keratocyte shape depends on the distribution of the traction forces, and that the magnitude of the traction forces depends on the area of the cells. PMID:26754329

  3. High Resolution Traction Force Microscopy Based on Experimental and Computational Advances

    PubMed Central

    Sabass, Benedikt; Gardel, Margaret L.; Waterman, Clare M.; Schwarz, Ulrich S.

    2008-01-01

    Cell adhesion and migration crucially depend on the transmission of actomyosin-generated forces through sites of focal adhesion to the extracellular matrix. Here we report experimental and computational advances in improving the resolution and reliability of traction force microscopy. First, we introduce the use of two differently colored nanobeads as fiducial markers in polyacrylamide gels and explain how the displacement field can be computationally extracted from the fluorescence data. Second, we present different improvements regarding standard methods for force reconstruction from the displacement field, which are the boundary element method, Fourier-transform traction cytometry, and traction reconstruction with point forces. Using extensive data simulation, we show that the spatial resolution of the boundary element method can be improved considerably by splitting the elastic field into near, intermediate, and far field. Fourier-transform traction cytometry requires considerably less computer time, but can achieve a comparable resolution only when combined with Wiener filtering or appropriate regularization schemes. Both methods tend to underestimate forces, especially at small adhesion sites. Traction reconstruction with point forces does not suffer from this limitation, but is only applicable with stationary and well-developed adhesion sites. Third, we combine these advances and for the first time reconstruct fibroblast traction with a spatial resolution of ∼1 μm. PMID:17827246

  4. Traction-drive force transmission for telerobotic joints

    NASA Technical Reports Server (NTRS)

    Williams, D. M.; Kuban, D. P.

    1989-01-01

    A mechanism which meets the requirements of a teleoperated manipulator and those of an autonomous robot is discussed. The mechanism is a traction-drive differential that uses variable preload mechanisms. The differential provides compact design, with dextrous motion range and torque density similar to geared systems. The traction drive offers high stiffness to backlash for good robotic performance. The variable-loading mechanism (VLM) minimizes the drive-train friction for improved teleoperation. This combination provides a mechanism to allow advanced manipulation with either teleoperated control or autonomous robotic operation. The design principles of both major components of the joint mechanism are described.

  5. The Regulation of Traction Force in Relation to Cell Shape and Focal Adhesions

    PubMed Central

    Rape, Andrew; Guo, Wei-hui; Wang, Yu-li

    2011-01-01

    Mechanical forces provide critical inputs for proper cellular functions. The interplay between the generation of, and response to, mechanical forces regulate such cellular processes as differentiation, proliferation, and migration. We postulate that adherent cells respond to a number of physical and topographical factors, including cell size and shape, by detecting the magnitude and/or distribution of traction forces under different conditions. To address this possibility we introduce a new simple method for precise micropatterning of hydrogels, and then apply the technique to systematically investigate the relationship between cell geometry, focal adhesions, and traction forces in cells with a series of spread areas and aspect ratios. Contrary to previous findings, we find that traction force is not determined primarily by the cell spreading area but by the distance from cell center to the perimeter. This distance in turn controls traction forces by regulating the size of focal adhesions, such that constraining the size of focal adhesions by micropatterning can override the effect of geometry. We propose that the responses of traction forces to center-periphery distance, possibly through a positive feedback mechanism that regulates focal adhesions, provide the cell with the information on its own shape and size. A similar positive feedback control may allow cells to respond to a variety of physical or topographical signals via a unified mechanism. PMID:21163521

  6. Both contractile axial and lateral traction force dynamics drive amoeboid cell motility

    PubMed Central

    Bastounis, Effie; Meili, Ruedi; Álvarez-González, Begoña; Francois, Joshua; del Álamo, Juan C.; Lasheras, Juan C.

    2014-01-01

    Chemotaxing Dictyostelium discoideum cells adapt their morphology and migration speed in response to intrinsic and extrinsic cues. Using Fourier traction force microscopy, we measured the spatiotemporal evolution of shape and traction stresses and constructed traction tension kymographs to analyze cell motility as a function of the dynamics of the cell’s mechanically active traction adhesions. We show that wild-type cells migrate in a step-wise fashion, mainly forming stationary traction adhesions along their anterior–posterior axes and exerting strong contractile axial forces. We demonstrate that lateral forces are also important for motility, especially for migration on highly adhesive substrates. Analysis of two mutant strains lacking distinct actin cross-linkers (mhcA− and abp120− cells) on normal and highly adhesive substrates supports a key role for lateral contractions in amoeboid cell motility, whereas the differences in their traction adhesion dynamics suggest that these two strains use distinct mechanisms to achieve migration. Finally, we provide evidence that the above patterns of migration may be conserved in mammalian amoeboid cells. PMID:24637328

  7. Traction forces mediated by integrin signaling are necessary for definitive endoderm specification.

    PubMed

    Taylor-Weiner, Hermes; Ravi, Neeraja; Engler, Adam J

    2015-05-15

    Pluripotent embryonic stem cells (ESCs) exert low-traction forces on their niche in vitro whereas specification to definitive endoderm in vivo coincides with force-mediated motility, suggesting a differentiation-mediated switch. However, the onset of contractility and extent to which force-mediated integrin signaling regulates fate choices is not understood. To address the requirement of tractions forces for differentiation, we examined mouse embryonic stem cell (ESC) specification towards definitive endoderm on fibrillar fibronectin containing a deformation-sensitive FRET probe. Inhibiting contractility resulted in an increase in the observed fibronectin FRET intensity ratio but also decreased the amount of phosphorylated nuclear SMAD2, leading to reduced expression of the definitive endoderm marker SOX17. By contrast ESCs maintained in pluripotency medium did not exert significant tractions against the fibronectin matrix. When laminin-111 was added to fibrillar matrices to improve the efficiency of definitive endoderm induction, ESCs decreased their fibronectin traction forces in a laminin-dependent manner; blocking the laminin-binding α3-integrin restored fibronectin matrix deformation and reduced SOX17 expression and SMAD2 phosphorylation, probably because of compensation of inhibitory signaling from SMAD7 after 5 days in culture. These data imply that traction forces and integrin signaling are important regulators of early fate decisions in ESCs. PMID:25908864

  8. Tracking traction force changes of single cells on the liquid crystal surface.

    PubMed

    Soon, Chin Fhong; Tee, Kian Sek; Youseffi, Mansour; Denyer, Morgan C T

    2015-03-01

    Cell migration is a key contributor to wound repair. This study presents findings indicating that the liquid crystal based cell traction force transducer (LCTFT) system can be used in conjunction with a bespoke cell traction force mapping (CTFM) software to monitor cell/surface traction forces from quiescent state in real time. In this study, time-lapse photo microscopy allowed cell induced deformations in liquid crystal coated substrates to be monitored and analyzed. The results indicated that the system could be used to monitor the generation of cell/surface forces in an initially quiescent cell, as it migrated over the culture substrate, via multiple points of contact between the cell and the surface. Future application of this system is the real-time assaying of the pharmacological effects of cytokines on the mechanics of cell migration. PMID:25808839

  9. A Novel Cell Traction Force Microscopy to Study Multi-Cellular System

    PubMed Central

    Anand, Sandeep V.; Saif, Taher A.

    2014-01-01

    Traction forces exerted by adherent cells on their microenvironment can mediate many critical cellular functions. Accurate quantification of these forces is essential for mechanistic understanding of mechanotransduction. However, most existing methods of quantifying cellular forces are limited to single cells in isolation, whereas most physiological processes are inherently multi-cellular in nature where cell-cell and cell-microenvironment interactions determine the emergent properties of cell clusters. In the present study, a robust finite-element-method-based cell traction force microscopy technique is developed to estimate the traction forces produced by multiple isolated cells as well as cell clusters on soft substrates. The method accounts for the finite thickness of the substrate. Hence, cell cluster size can be larger than substrate thickness. The method allows computing the traction field from the substrate displacements within the cells' and clusters' boundaries. The displacement data outside these boundaries are not necessary. The utility of the method is demonstrated by computing the traction generated by multiple monkey kidney fibroblasts (MKF) and human colon cancerous (HCT-8) cells in close proximity, as well as by large clusters. It is found that cells act as individual contractile groups within clusters for generating traction. There may be multiple of such groups in the cluster, or the entire cluster may behave a single group. Individual cells do not form dipoles, but serve as a conduit of force (transmission lines) over long distances in the cluster. The cell-cell force can be either tensile or compressive depending on the cell-microenvironment interactions. PMID:24901766

  10. Dynamic peripheral traction forces balance stable neurite tension in regenerating Aplysia bag cell neurons

    PubMed Central

    Hyland, Callen; Mertz, Aaron F.; Forscher, Paul; Dufresne, Eric

    2014-01-01

    Growth cones of elongating neurites exert force against the external environment, but little is known about the role of force in outgrowth or its relationship to the mechanical organization of neurons. We used traction force microscopy to examine patterns of force in growth cones of regenerating Aplysia bag cell neurons. We find that traction is highest in the peripheral actin-rich domain and internal stress reaches a plateau near the transition between peripheral and central microtubule-rich domains. Integrating stress over the area of the growth cone reveals that total scalar force increases with area but net tension on the neurite does not. Tensions fall within a limited range while a substantial fraction of the total force can be balanced locally within the growth cone. Although traction continuously redistributes during extension and retraction of the peripheral domain, tension is stable over time, suggesting that tension is a tightly regulated property of the neurite independent of growth cone dynamics. We observe that redistribution of traction in the peripheral domain can reorient the end of the neurite shaft. This suggests a role for off-axis force in growth cone turning and neuronal guidance. PMID:24825441

  11. Dynamic peripheral traction forces balance stable neurite tension in regenerating Aplysia bag cell neurons.

    PubMed

    Hyland, Callen; Mertz, Aaron F; Forscher, Paul; Dufresne, Eric

    2014-01-01

    Growth cones of elongating neurites exert force against the external environment, but little is known about the role of force in outgrowth or its relationship to the mechanical organization of neurons. We used traction force microscopy to examine patterns of force in growth cones of regenerating Aplysia bag cell neurons. We find that traction is highest in the peripheral actin-rich domain and internal stress reaches a plateau near the transition between peripheral and central microtubule-rich domains. Integrating stress over the area of the growth cone reveals that total scalar force increases with area but net tension on the neurite does not. Tensions fall within a limited range while a substantial fraction of the total force can be balanced locally within the growth cone. Although traction continuously redistributes during extension and retraction of the peripheral domain, tension is stable over time, suggesting that tension is a tightly regulated property of the neurite independent of growth cone dynamics. We observe that redistribution of traction in the peripheral domain can reorient the end of the neurite shaft. This suggests a role for off-axis force in growth cone turning and neuronal guidance. PMID:24825441

  12. Probing cellular traction forces with magnetic nanowires and microfabricated force sensor arrays

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Chia; Kramer, Corinne M.; Chen, Christopher S.; Reich, Daniel H.

    2012-02-01

    In this paper, the use of magnetic nanowires for the study of cellular response to force is demonstrated. High-aspect ratio Ni rods with diameter 300 nm and lengths up to 20 μm were bound to or internalized by pulmonary artery smooth muscle cells (SMCs) cultured on arrays of flexible micropost force sensors. Forces and torques were applied to the cells by driving the nanowires with AC magnetic fields in the frequency range 0.1-10 Hz, and the changes in cellular contractile forces were recorded with the microposts. These local stimulations yield global force reinforcement of the cells’ traction forces, but this contractile reinforcement can be effectively suppressed upon addition of a calcium channel blocker, ruthenium red, suggesting the role of calcium channels in the mechanical response. The responsiveness of the SMCs to actuation depends on the frequency of the applied stimulation. These results show that the combination of magnetic nanoparticles and micropatterned, flexible substrates can provide new approaches to the study of cellular mechanotransduction.

  13. Traction force microscopy on soft elastic substrates: A guide to recent computational advances.

    PubMed

    Schwarz, Ulrich S; Soiné, Jérôme R D

    2015-11-01

    The measurement of cellular traction forces on soft elastic substrates has become a standard tool for many labs working on mechanobiology. Here we review the basic principles and different variants of this approach. In general, the extraction of the substrate displacement field from image data and the reconstruction procedure for the forces are closely linked to each other and limited by the presence of experimental noise. We discuss different strategies to reconstruct cellular forces as they follow from the foundations of elasticity theory, including two- versus three-dimensional, inverse versus direct and linear versus non-linear approaches. We also discuss how biophysical models can improve force reconstruction and comment on practical issues like substrate preparation, image processing and the availability of software for traction force microscopy. This article is part of a Special Issue entitled: Mechanobiology. PMID:26026889

  14. Free Form Deformation–Based Image Registration Improves Accuracy of Traction Force Microscopy

    PubMed Central

    Jorge-Peñas, Alvaro; Izquierdo-Alvarez, Alicia; Aguilar-Cuenca, Rocio; Vicente-Manzanares, Miguel; Garcia-Aznar, José Manuel; Van Oosterwyck, Hans; de-Juan-Pardo, Elena M.; Ortiz-de-Solorzano, Carlos; Muñoz-Barrutia, Arrate

    2015-01-01

    Traction Force Microscopy (TFM) is a widespread method used to recover cellular tractions from the deformation that they cause in their surrounding substrate. Particle Image Velocimetry (PIV) is commonly used to quantify the substrate’s deformations, due to its simplicity and efficiency. However, PIV relies on a block-matching scheme that easily underestimates the deformations. This is especially relevant in the case of large, locally non-uniform deformations as those usually found in the vicinity of a cell’s adhesions to the substrate. To overcome these limitations, we formulate the calculation of the deformation of the substrate in TFM as a non-rigid image registration process that warps the image of the unstressed material to match the image of the stressed one. In particular, we propose to use a B-spline -based Free Form Deformation (FFD) algorithm that uses a connected deformable mesh to model a wide range of flexible deformations caused by cellular tractions. Our FFD approach is validated in 3D fields using synthetic (simulated) data as well as with experimental data obtained using isolated endothelial cells lying on a deformable, polyacrylamide substrate. Our results show that FFD outperforms PIV providing a deformation field that allows a better recovery of the magnitude and orientation of tractions. Together, these results demonstrate the added value of the FFD algorithm for improving the accuracy of traction recovery. PMID:26641883

  15. Model-based Traction Force Microscopy Reveals Differential Tension in Cellular Actin Bundles

    PubMed Central

    Soiné, Jérôme R. D.; Brand, Christoph A.; Stricker, Jonathan; Oakes, Patrick W.; Gardel, Margaret L.; Schwarz, Ulrich S.

    2015-01-01

    Adherent cells use forces at the cell-substrate interface to sense and respond to the physical properties of their environment. These cell forces can be measured with traction force microscopy which inverts the equations of elasticity theory to calculate them from the deformations of soft polymer substrates. We introduce a new type of traction force microscopy that in contrast to traditional methods uses additional image data for cytoskeleton and adhesion structures and a biophysical model to improve the robustness of the inverse procedure and abolishes the need for regularization. We use this method to demonstrate that ventral stress fibers of U2OS-cells are typically under higher mechanical tension than dorsal stress fibers or transverse arcs. PMID:25748431

  16. Model-based traction force microscopy reveals differential tension in cellular actin bundles.

    PubMed

    Soiné, Jérôme R D; Brand, Christoph A; Stricker, Jonathan; Oakes, Patrick W; Gardel, Margaret L; Schwarz, Ulrich S

    2015-03-01

    Adherent cells use forces at the cell-substrate interface to sense and respond to the physical properties of their environment. These cell forces can be measured with traction force microscopy which inverts the equations of elasticity theory to calculate them from the deformations of soft polymer substrates. We introduce a new type of traction force microscopy that in contrast to traditional methods uses additional image data for cytoskeleton and adhesion structures and a biophysical model to improve the robustness of the inverse procedure and abolishes the need for regularization. We use this method to demonstrate that ventral stress fibers of U2OS-cells are typically under higher mechanical tension than dorsal stress fibers or transverse arcs. PMID:25748431

  17. Flexible substrata for the detection of cellular traction forces

    NASA Technical Reports Server (NTRS)

    Beningo, Karen A.; Wang, Yu-Li

    2002-01-01

    By modulating adhesion signaling and cytoskeletal organization, mechanical forces play an important role in various cellular functions, from propelling cell migration to mediating communication between cells. Recent developments have resulted in several new approaches for the detection, analysis and visualization of mechanical forces generated by cultured cells. Combining these methods with other approaches, such as green-fluorescent protein (GFP) imaging and gene manipulation, proves to be particularly powerful for analyzing the interplay between extracellular physical forces and intracellular chemical events.

  18. Creep force modelling for rail traction vehicles based on the Fastsim algorithm

    NASA Astrophysics Data System (ADS)

    Spiryagin, Maksym; Polach, Oldrich; Cole, Colin

    2013-11-01

    The evaluation of creep forces is a complex task and their calculation is a time-consuming process for multibody simulation (MBS). A methodology of creep forces modelling at large traction creepages has been proposed by Polach [Creep forces in simulations of traction vehicles running on adhesion limit. Wear. 2005;258:992-1000; Influence of locomotive tractive effort on the forces between wheel and rail. Veh Syst Dyn. 2001(Suppl);35:7-22] adapting his previously published algorithm [Polach O. A fast wheel-rail forces calculation computer code. Veh Syst Dyn. 1999(Suppl);33:728-739]. The most common method for creep force modelling used by software packages for MBS of running dynamics is the Fastsim algorithm by Kalker [A fast algorithm for the simplified theory of rolling contact. Veh Syst Dyn. 1982;11:1-13]. However, the Fastsim code has some limitations which do not allow modelling the creep force - creep characteristic in agreement with measurements for locomotives and other high-power traction vehicles, mainly for large traction creep at low-adhesion conditions. This paper describes a newly developed methodology based on a variable contact flexibility increasing with the ratio of the slip area to the area of adhesion. This variable contact flexibility is introduced in a modification of Kalker's code Fastsim by replacing the constant Kalker's reduction factor, widely used in MBS, by a variable reduction factor together with a slip-velocity-dependent friction coefficient decreasing with increasing global creepage. The proposed methodology is presented in this work and compared with measurements for different locomotives. The modification allows use of the well recognised Fastsim code for simulation of creep forces at large creepages in agreement with measurements without modifying the proven modelling methodology at small creepages.

  19. Cell Shapes and Traction Forces Determine Stress in Motile Confluent Tissue

    NASA Astrophysics Data System (ADS)

    Yang, Xingbo; Bi, Dapeng; Czajkowski, Michael; Manning, Lisa; Marchetti, Cristina

    Collective cell migration is a highly regulated process involved in wound healing, cancer metastasis and morphogenesis. The understanding of the regulatory mechanism requires the study of mechanical interactions among cells that coordinate their active motion. To this end, we develop a method that determines cellular forces and tissue stresses from experimentally accessible cell shapes and traction forces. This approach allows us for the first time to calculate membrane tensions and hydrostatic pressures at a cellular level in collective migrating cell layers out of equilibrium. It helps us understand the mechanical origin of tissue stresses as previous inferred using Traction Force Microscopy (TFM). We test this approach on a new model of motile confluent tissue, which we term Self-propelled Voronoi Model (SPV) that incorporates cell elasticity, Contractility and motility. With the model, we explore the mechanical properties of confluent motile tissue as a function of cell activities and cell shapes in various geometries.

  20. Rho Mediates the Shear-Enhancement of Endothelial Cell Migration and Traction Force Generation

    PubMed Central

    Shiu, Yan-Ting; Li, Song; Marganski, William A.; Usami, Shunichi; Schwartz, Martin A.; Wang, Yu-Li; Dembo, Micah; Chien, Shu

    2004-01-01

    The migration of vascular endothelial cells in vivo occurs in a fluid dynamic environment due to blood flow, but the role of hemodynamic forces in cell migration is not yet completely understood. Here we investigated the effect of shear stress, the frictional drag of blood flowing over the cell surface, on the migration speed of individual endothelial cells on fibronectin-coated surfaces, as well as the biochemical and biophysical bases underlying this shear effect. Under static conditions, cell migration speed had a bell-shaped relationship with fibronectin concentration. Shear stress significantly increased the migration speed at all fibronectin concentrations tested and shifted the bell-shaped curve upwards. Shear stress also induced the activation of Rho GTPase and increased the traction force exerted by endothelial cells on the underlying substrate, both at the leading edge and the rear, suggesting that shear stress enhances both the frontal forward-pulling force and tail retraction. The inhibition of a Rho-associated kinase, p160ROCK, decreased the traction force and migration speed under both static and shear conditions and eliminated the shear-enhancement of migration speed. Our results indicate that shear stress enhances the migration speed of endothelial cells by modulating the biophysical force of tractions through the biochemical pathway of Rho-p160ROCK. PMID:15041692

  1. Experimental and numerical determination of cellular traction force on polymeric hydrogels

    PubMed Central

    Ng, Soon Seng; Li, Chuan; Chan, Vincent

    2011-01-01

    Anchorage-dependent cells such as smooth muscle cells (SMCs) rely on the transmission of actomyosin-generated traction forces to adhere and migrate on the extracellular matrix. The cellular traction forces exerted by SMCs on substrate can be measured from the deformation of substrate with embedded fluorescent markers. With the synchronous use of phase-contrast and fluorescent microscopy, the deformation of polyacrylamide (PAM) gel substrate can be quantitatively determined using particle image velocimetry. This displacement map is then input as boundary conditions for the stress analysis on PAM gel by the finite-element method. In addition to optical microscopy, atomic force microscopy was also used to characterize the PAM substrate using the contact mode, from which the elasticity of PAM can be quantified using Hertzian theory. This provides baseline information for the stress analysis of PAM gel deformation. The material model introduced for the computational part is the Mooney–Rivlin constitutive law because of its long proven usefulness in predicting polymers' mechanical behaviour. Numerical results showed that adhesive stresses are high around the cell edges, which is in accordance with the general phenomena of cellular focal adhesion. Further calculations on the total traction forces indicate a slightly contact-dominated regime for a broad range of Mooney–Rivlin stiffnesses. PMID:23050082

  2. Modification of Cellular Cholesterol Content Affects Traction Force, Adhesion and Cell Spreading

    PubMed Central

    Norman, Leann L.; Oetama, Ratna J.; Dembo, Micah; Byfield, F.; Hammer, Daniel A.; Levitan, Irena; Aranda-Espinoza, Helim

    2011-01-01

    Cellular cholesterol is a critical component of the plasma membrane, and plays a key role in determining the physical properties of the lipid bilayer, such as elasticity, viscosity, and permeability. Surprisingly, it has been shown that cholesterol depletion increases cell stiffness, not due to plasma membrane stiffening, but rather, due to the interaction between the actin cytoskeleton and the plasma membrane. This indicates that traction stresses of the acto-myosin complex likely increase during cholesterol depletion. Here we use force traction microscopy to quantify the forces individual cells are exerting on the substrate, and total internal reflection fluorescence microscopy as well as interference reflection microscopy to observe cell–substrate adhesion and spreading. We show that single cells depleted of cholesterol produce larger traction forces and have large focal adhesions compared to untreated or cholesterol-enriched cells. Cholesterol depletion also causes a decrease in adhesion area for both single cells and monolayers. Spreading experiments illustrate a decrease in spreading area for cholesterol-depleted cells, and no effect on cholesterol-enriched cells. These results demonstrate that cholesterol plays an important role in controlling and regulating the cell–substrate interactions through the actin–plasma membrane complex, cell–cell adhesion, and spreading. PMID:21461187

  3. Spatiotemporal dynamics of traction forces show three contraction centers in migratory neurons

    PubMed Central

    Jiang, Jian; Zhang, Zheng-hong; Yuan, Xiao-bin

    2015-01-01

    Traction force against the substrate is required for neuronal migration, but how it is generated and regulated remains controversial. Using traction force microscopy, we showed in cultured granule cells the coexistence of three distinct contraction centers (CCs) that are located at the distal and proximal regions of the leading process as well as at the trailing process, regions exhibiting high-level myosin-II activities. The CC activities depended on myosin-II, actin filaments, and microtubules, as well as substrate adhesion, and exhibited apparently independent fluctuation. The difference of strain energies associated with CC activities between leading versus trailing processes tightly correlated with the displacement of the soma at any given time. Application of brain-derived neurotrophic factor (BDNF) and Slit2, factors known to guide neuronal migration, at the leading process altered CC activities by regulating the small GTPases Cdc42 and RhoA, respectively, leading to forward and rearward soma translocation. These results delineate the multiple origins and spatiotemporal dynamics of the traction force underlying neuronal migration. PMID:26056143

  4. Spatiotemporal dynamics of traction forces show three contraction centers in migratory neurons.

    PubMed

    Jiang, Jian; Zhang, Zheng-hong; Yuan, Xiao-bin; Poo, Mu-ming

    2015-06-01

    Traction force against the substrate is required for neuronal migration, but how it is generated and regulated remains controversial. Using traction force microscopy, we showed in cultured granule cells the coexistence of three distinct contraction centers (CCs) that are located at the distal and proximal regions of the leading process as well as at the trailing process, regions exhibiting high-level myosin-II activities. The CC activities depended on myosin-II, actin filaments, and microtubules, as well as substrate adhesion, and exhibited apparently independent fluctuation. The difference of strain energies associated with CC activities between leading versus trailing processes tightly correlated with the displacement of the soma at any given time. Application of brain-derived neurotrophic factor (BDNF) and Slit2, factors known to guide neuronal migration, at the leading process altered CC activities by regulating the small GTPases Cdc42 and RhoA, respectively, leading to forward and rearward soma translocation. These results delineate the multiple origins and spatiotemporal dynamics of the traction force underlying neuronal migration. PMID:26056143

  5. A hemidesmosomal protein regulates actin dynamics and traction forces in motile keratinocytes.

    PubMed

    Hiroyasu, Sho; Colburn, Zachary T; Jones, Jonathan C R

    2016-06-01

    During wound healing of the skin, keratinocytes disassemble hemidesmosomes and reorganize their actin cytoskeletons in order to exert traction forces on and move directionally over the dermis. Nonetheless, the transmembrane hemidesmosome component collagen XVII (ColXVII) is found in actin-rich lamella, situated behind the lamellipodium. A set of actin bundles, along which ColXVII colocalizes with actinin4, is present at each lamella. Knockdown of either ColXVII or actinin4 not only inhibits directed migration of keratinocytes but also relieves constraints on actin bundle retrograde movement at the site of lamella, such that actin bundle movement is enhanced more than 5-fold. Moreover, whereas control keratinocytes move in a stepwise fashion over a substrate by generating alternating traction forces, of up to 1.4 kPa, at each flank of the lamellipodium, ColXVII knockdown keratinocytes fail to do so. In summary, our data indicate that ColXVII-actinin4 complexes at the lamella of a moving keratinocyte regulate actin dynamics, thereby determining the direction of cell movement.-Hiroyasu, S., Colburn, Z. T., Jones, J. C. R. A hemidesmosomal protein regulates actin dynamics and traction forces in motile keratinocytes. PMID:26936359

  6. Training and certification of doctors of chiropractic in delivering manual cervical traction forces: Results of a longitudinal observational study

    PubMed Central

    Gudavalli, Maruti Ram; Vining, Robert D.; Salsbury, Stacie A.; Goertz, Christine M.

    2014-01-01

    Objective Doctors of chiropractic (DCs) use manual cervical distraction to treat patients with neck pain. Previous research demonstrates variability in traction forces generated by different DCs. This article reports on a training protocol and monthly certification process using bioengineering technology to standardize cervical traction force delivery among clinicians. Methods This longitudinal observational study evaluated a training and certification process for DCs who provided force-based manual cervical distraction during a randomized clinical trial. The DCs completed a 7-week initial training that included instructional lectures, observation, and guided practice by a clinical expert, followed by 3 hours of weekly practice sessions delivering the technique to asymptomatic volunteers who served as simulated patients. An instrument-modified table and computer software provided the DCs with real-time audible and visual feedback on the traction forces they generated and graphical displays of the magnitude of traction forces as a function of time immediately after the delivery of the treatment. The DCs completed monthly certifications on traction force delivery throughout the trial. Descriptive accounts of certification attempts are provided. Results Two DCs achieved certification in traction force delivery over 10 consecutive months. No certification required more than 3 attempts at C5 and occiput contacts for 3 force ranges (0–20 N, 21–50 N, and 51–100 N). Conclusions This study demonstrates the feasibility of a training protocol and certification process using bioengineering technology for training DCs to deliver manual cervical distraction within specified traction force ranges over a 10-month period. PMID:25237767

  7. Characterization of Intracellular Streaming and Traction Forces in Migrating Physarum Plasmodia

    NASA Astrophysics Data System (ADS)

    Zhang, Shun; Meili, Ruedi; Guy, Robert; Lasheras, Juan; Del Alamo, Juan C.

    2014-11-01

    Physarum plasmodium is a model organism for cell migration that exhibits fast intracellular streaming. Single amoebae were seeded and allowed to move on polyacrilamide gels that contained 0.5-micron fluorescent beads. Joint time-lapse sequences of intracellular streaming and gel deformation were acquired respectively in the bright and fluorescent fields under microscope. These images were analyzed using particle image velocimetry (PIV) algorithms, and the traction stresses applied by the amoebae on the surface were computed by solving the elastostatic equation for the gel using the measured bead displacements as boundary conditions. These measurements provide, for the first time, a joint characterization of intracellular mass transport and the forces applied on the substrate of motile amoeboid cells with high resolution in both time and space, enables a through study about the locomotive mechanism and the relation between intracellular flow and traction stress, shedding light on related biomimetic research. The results reveal a pronounced auto-oscillation character in intracellular flow, contact area, centroid speed and strain energy, all with the same periodicity about 100 seconds. Locomotion modes that were distinct in flow/ traction stress pattern as well as migration speed have been discovered and studied.

  8. Characterization of Intracellular Streaming and Traction Forces in Migrating Physarum Plasmodia

    NASA Astrophysics Data System (ADS)

    Zhang, Shun; Meili, Ruedi; Guy, Robert D.; Lasheras, Juan C.; Del Alamo, Juan C.

    2013-11-01

    Physarum plasmodium is a model organism for cell migration that exhibits fast intracellular streaming. Single amoebae were seeded and allowed to move on polyacrilamide gels that contained 0.2 μm fluorescent beads. Joint time-lapse sequences of intracellular streaming and gel deformation were acquired respectively in the bright and fluorescent fields of a confocal microscope. Images were analyzed using particle image velocimetry (PIV) algorithms, and the traction stresses applied by the amoebae on the surface were computed by solving the elastostatic equation for the gel. These measurements provide, for the first time, a joint characterization of intracellular mass transport and the forces applied on the substrate of motile amoeboid cells with high resolution in both time and space, enables a through study about the locomotive mechanism and the relation between intracellular flow and traction stress, shedding light on related biomimetic research. The results reveal a pronounced auto-oscillation character in intracellular flow, contact area, centroid speed and strain energy, all with the same periodicity about 60 seconds. Adhesion sites are found to be almost stationary while a traction wave propagates from the tail to the anterior region in each cycle.

  9. Modeling the mechanics of cells in the cell-spreading process driven by traction forces

    NASA Astrophysics Data System (ADS)

    Fang, Yuqiang; Lai, King W. C.

    2016-04-01

    Mechanical properties of cells and their mechanical interaction with the extracellular environments are main factors influencing cellular function, thus indicating the progression of cells in different disease states. By considering the mechanical interactions between cell adhesion molecules and the extracellular environment, we developed a cell mechanical model that can characterize the mechanical changes in cells during cell spreading. A cell model was established that consisted of various main subcellular components, including cortical cytoskeleton, nuclear envelope, actin filaments, intermediate filaments, and microtubules. We demonstrated the structural changes in subcellular components and the changes in spreading areas during cell spreading driven by traction forces. The simulation of nanoindentation tests was conducted by integrating the indenting force to the cell model. The force-indentation curve of the cells at different spreading states was simulated, and the results showed that cell stiffness increased with increasing traction forces, which were consistent with the experimental results. The proposed cell mechanical model provides a strategy to investigate the mechanical interactions of cells with the extracellular environments through the adhesion molecules and to reveal the cell mechanical properties at the subcellular level as cells shift from the suspended state to the adherent state.

  10. Imaging in-plane and normal stresses near an interface crack using traction force microscopy

    PubMed Central

    Xu, Ye; Engl, Wilfried C.; Jerison, Elizabeth R.; Wallenstein, Kevin J.; Hyland, Callen; Wilen, Larry A.; Dufresne, Eric R.

    2010-01-01

    Colloidal coatings, such as paint, are all around us. However, we know little about the mechanics of the film-forming process because the composition and properties of drying coatings vary dramatically in space and time. To surmount this challenge, we extend traction force microscopy to quantify the spatial distribution of all three components of the stress at the interface of two materials. We apply this approach to image stress near the tip of a propagating interface crack in a drying colloidal coating and extract the stress intensity factor. PMID:20696929

  11. Integrin-Matrix Clusters Form Podosome-like Adhesions in the Absence of Traction Forces

    PubMed Central

    Yu, Cheng-han; Rafiq, Nisha Bte Mohd; Krishnasamy, Anitha; Hartman, Kevin L.; Jones, Gareth E.; Bershadsky, Alexander D.; Sheetz, Michael P.

    2013-01-01

    Summary Matrix-activated integrins can form different adhesion structures. We report that nontransformed fibroblasts develop podosome-like adhesions when spread on fluid Arg-Gly-Asp peptide (RGD)-lipid surfaces, whereas they habitually form focal adhesions on rigid RGD glass surfaces. Similar to classic macrophage podosomes, the podosome-like adhesions are protrusive and characterized by doughnut-shaped RGD rings that surround characteristic core components including F-actin, N-WASP, and Arp2/Arp3. Furthermore, there are 18 podosome markers in these adhesions, though they lack matrix metalloproteinases that characterize invadopodia and podosomes of Src-transformed cells. When nontransformed cells develop force on integrin-RGD clusters by pulling RGD lipids to prefabricated rigid barriers (metal lines spaced by 1–2 μm), these podosomes fail to form and instead form focal adhesions. The formation of podosomes on fluid surfaces is mediated by local activation of phosphoinositide 3-kinase (PI3K) and the production of phosphatidylinositol-(3,4,5)-triphosphate (PIP3) in a FAK/PYK2-dependent manner. Enrichment of PIP3 precedes N-WASP activation and the recruitment of RhoA-GAP ARAP3. We propose that adhesion structures can be modulated by traction force development and that production of PIP3 stimulates podosome formation and subsequent RhoA downregulation in the absence of traction force. PMID:24290759

  12. Traction force microscopy in rapidly moving cells reveals separate roles for ROCK and MLCK in the mechanics of retraction.

    PubMed

    Morin, Timothy R; Ghassem-Zadeh, Sean A; Lee, Juliet

    2014-08-15

    Retraction is a major rate-limiting step in cell motility, particularly in slow moving cell types that form large stable adhesions. Myosin II dependent contractile forces are thought to facilitate detachment by physically pulling up the rear edge. However, retraction can occur in the absence of myosin II activity in cell types that form small labile adhesions. To investigate the role of contractile force generation in retraction, we performed traction force microscopy during the movement of fish epithelial keratocytes. By correlating changes in local traction stress at the rear with the area retracted, we identified four distinct modes of retraction. "Recoil" retractions are preceded by a rise in local traction stress, while rear edge is temporarily stuck, followed by a sharp drop in traction stress upon detachment. This retraction type was most common in cells generating high average traction stress. In "pull" type retractions local traction stress and area retracted increase concomitantly. This was the predominant type of retraction in keratocytes and was observed mostly in cells generating low average traction stress. "Continuous" type retractions occur without any detectable change in traction stress, and are seen in cells generating low average traction stress. In contrast, to many other cell types, "release" type retractions occur in keratocytes following a decrease in local traction stress. Our identification of distinct modes of retraction suggests that contractile forces may play different roles in detachment that are related to rear adhesion strength. To determine how the regulation of contractility via MLCK or Rho kinase contributes to the mechanics of detachment, inhibitors were used to block or augment these pathways. Modulation of MLCK activity led to the most rapid change in local traction stress suggesting its importance in regulating attachment strength. Surprisingly, Rho kinase was not required for detachment, but was essential for localizing

  13. Vinculin-dependent actin bundling regulates cell migration and traction forces

    PubMed Central

    Jannie, Karry M.; Ellerbroek, Shawn M.; Zhou, Dennis W.; Chen, Sophia; Crompton, David J.; García, Andrés J.; DeMali, Kris A.

    2015-01-01

    Vinculin binding to actin filaments is thought to be critical for force transduction within a cell, but direct experimental evidence to support this conclusion has been limited . In this study, we found mutation (R1049E) of the vinculin tail impairs its ability to bind F-actin, stimulate actin polymerization, and bundle F-actin in vitro. Further , mutant (R1049E) vinculin expressing cells are altered in cell migration, which is accompanied by changes in cell adhesion, cell spreading, and cell generation of traction forces, providing direct evidence for the critical role of vinculin in mechanotransduction at adhesion sites. Lastly, we herein discuss the viability of models detailing the F-actin-binding surface on vinculin in context of our mutational analysis. PMID:25358683

  14. Development of a novel liquid crystal based cell traction force transducer system.

    PubMed

    Soon, C F; Youseffi, M; Berends, R F; Blagden, N; Denyer, M C T

    2013-01-15

    Keratinocyte traction forces play a crucial role in wound healing. The aim of this study was to develop a novel cell traction force (CTF) transducer system based on cholesteryl ester liquid crystals (LC). Keratinocytes cultured on LC induced linear and isolated deformation lines in the LC surface. As suggested by the fluorescence staining, the deformation lines appeared to correlate with the forces generated by the contraction of circumferential actin filaments which were transmitted to the LC surface via the focal adhesions. Due to the linear viscoelastic behavior of the LC, Hooke's equation was used to quantify the CTFs by associating Young's modulus of LC to the cell induced stresses and biaxial strain in forming the LC deformation. Young's modulus of the LC was profiled by using spherical indentation and determined at approximately 87.1±17.2kPa. A new technique involving cytochalasin-B treatment was used to disrupt the intracellular force generating actin fibers, and consequently the biaxial strain in the LC induced by the cells was determined. Due to the improved sensitivity and spatial resolution (∼1μm) of the LC based CTF transducer, a wide range of CTFs was determined (10-120nN). These were found to be linearly proportional to the length of the deformations. The linear relationship of CTF-deformations was then applied in a bespoke CTF mapping software to estimate CTFs and to map CTF fields. The generated CTF map highlighted distinct distributions and different magnitude of CTFs were revealed for polarized and non-polarized keratinocytes. PMID:22809522

  15. Characterization of Intracellular Streaming and Traction Forces in Migrating Physarum Plasmodia

    NASA Astrophysics Data System (ADS)

    Zhang, Shun; Lewis, Owen; Guy, Robert; Del Alamo, Juan Carlos

    2015-11-01

    Physarum plasmodium is a model organism for cell migration that exhibits fast intracellular streaming. Single amoebae were seeded and allowed to move on polyacrilamide gels that contained 0.5-micron fluorescent beads. Joint time-lapse sequences of intracellular streaming and gel deformation were acquired respectively in the bright and fluorescent fields under microscope. These images were analyzed using particle image velocimetry (PIV) algorithms, and the traction stresses applied by the amoebae on the surface were computed by solving the elastostatic equation for the gel using the measured bead displacements as boundary conditions. These measurements provide, for the first time, a joint characterization of intracellular mass transport, the forces applied on the substrate and the signal of free intracellular calcium with high resolution in both time and space, enables a through study about the locomotive mechanism, shedding light on related biomimetic research. The results reveal a pronounced auto-oscillation character in intracellular flow, contact area, centroid speed and strain energy, all with the same periodicity about 100 seconds. Locomotion modes that were distinct in flow/ traction stress pattern as well as migration speed have been discovered and studied.

  16. Cellular adhesome screen identifies critical modulators of focal adhesion dynamics, cellular traction forces and cell migration behaviour

    PubMed Central

    Fokkelman, Michiel; Balcıoğlu, Hayri E.; Klip, Janna E.; Yan, Kuan; Verbeek, Fons J.; Danen, Erik H. J.; van de Water, Bob

    2016-01-01

    Cancer cells migrate from the primary tumour into surrounding tissue in order to form metastasis. Cell migration is a highly complex process, which requires continuous remodelling and re-organization of the cytoskeleton and cell-matrix adhesions. Here, we aimed to identify genes controlling aspects of tumour cell migration, including the dynamic organization of cell-matrix adhesions and cellular traction forces. In a siRNA screen targeting most cell adhesion-related genes we identified 200+ genes that regulate size and/or dynamics of cell-matrix adhesions in MCF7 breast cancer cells. In a subsequent secondary screen, the 64 most effective genes were evaluated for growth factor-induced cell migration and validated by tertiary RNAi pool deconvolution experiments. Four validated hits showed significantly enlarged adhesions accompanied by reduced cell migration upon siRNA-mediated knockdown. Furthermore, loss of PPP1R12B, HIPK3 or RAC2 caused cells to exert higher traction forces, as determined by traction force microscopy with elastomeric micropillar post arrays, and led to considerably reduced force turnover. Altogether, we identified genes that co-regulate cell-matrix adhesion dynamics and traction force turnover, thereby modulating overall motility behaviour. PMID:27531518

  17. Directional control of lamellipodia extension by constraining cell shape and orienting cell tractional forces

    NASA Technical Reports Server (NTRS)

    Parker, Kevin Kit; Brock, Amy Lepre; Brangwynne, Cliff; Mannix, Robert J.; Wang, Ning; Ostuni, Emanuele; Geisse, Nicholas A.; Adams, Josephine C.; Whitesides, George M.; Ingber, Donald E.

    2002-01-01

    Directed cell migration is critical for tissue morphogenesis and wound healing, but the mechanism of directional control is poorly understood. Here we show that the direction in which cells extend their leading edge can be controlled by constraining cell shape using micrometer-sized extracellular matrix (ECM) islands. When cultured on square ECM islands in the presence of motility factors, cells preferentially extended lamellipodia, filopodia, and microspikes from their corners. Square cells reoriented their stress fibers and focal adhesions so that tractional forces were concentrated in these corner regions. When cell tension was dissipated, lamellipodia extension ceased. Mechanical interactions between cells and ECM that modulate cytoskeletal tension may therefore play a key role in the control of directional cell motility.

  18. A Novel Method for Localizing Reporter Fluorescent Beads Near the Cell Culture Surface for Traction Force Microscopy

    PubMed Central

    Knoll, Samantha G.; Ali, M. Yakut; Saif, M. Taher A.

    2014-01-01

    PA gels have long been used as a platform to study cell traction forces due to ease of fabrication and the ability to tune their elastic properties. When the substrate is coated with an extracellular matrix protein, cells adhere to the gel and apply forces, causing the gel to deform. The deformation depends on the cell traction and the elastic properties of the gel. If the deformation field of the surface is known, surface traction can be calculated using elasticity theory. Gel deformation is commonly measured by embedding fluorescent marker beads uniformly into the gel. The probes displace as the gel deforms. The probes near the surface of the gel are tracked. The displacements reported by these probes are considered as surface displacements. Their depths from the surface are ignored. This assumption introduces error in traction force evaluations. For precise measurement of cell forces, it is critical for the location of the beads to be known. We have developed a technique that utilizes simple chemistry to confine fluorescent marker beads, 0.1 and 1 µm in diameter, in PA gels, within 1.6 μm of the surface. We coat a coverslip with poly-D-lysine (PDL) and fluorescent beads. PA gel solution is then sandwiched between the coverslip and an adherent surface. The fluorescent beads transfer to the gel solution during curing. After polymerization, the PA gel contains fluorescent beads on a plane close to the gel surface. PMID:25286326

  19. Asymmetry in traction forces produced by migrating preadipocytes is bounded to 33.

    PubMed

    Abuhattum, Shada; Weihs, Daphne

    2016-09-01

    Wound healing by gap closure is accomplished by the migratory cells within tissues. In fat tissue, the preadipocytes, stem cells committed to the adipose (fat) lineage, typically migrate into the wound area, and then differentiate into mature adipocytes to facilitate tissue repair and regeneration. While cell migration has previously been characterized, typically for fibroblasts, little is known about the dynamic, mechanical interactions of migrating cells with their microenvironment; cells crawl on a two-dimensional (2D) substrate by attaching and applying forces that allow them to extend leading edges and retract their rear. Moreover, preadipocytes, the highly migratory precursors of fat cells, have not been studied from this aspect. Here, we have evaluated the migration of preadipocytes, through their speed and directionality as well as the magnitude of the lateral forces applied during their migration on a 2D gel with Young's modulus of 2.44 kPa. We have found that the preadipocytes migrate non-directionally in the absence of chemoattractant, at an average rate of 0.27 µm/min, similar to fibroblasts. The preadipocytes exhibited a wide range of total traction forces (100-800 nN), and migrated along the long axis of their elongated morphology. Interestingly, we have observed an asymmetry in the location of force application between the lead and rear of the cells that was bounded in magnitude, where cells applied only up to 33% more force on either side; cell sides were defined relative to the minor axis of a bounding ellipse. These quantitative mechanobiological aspects of natural preadipocyte migration may shed light on the wound healing processes occurring in adipose tissue. PMID:27340101

  20. Collective cell traction force analysis on aligned smooth muscle cell sheet between three-dimensional microwalls

    PubMed Central

    Zhang, Ying; Ng, Soon Seng; Wang, Yilei; Feng, Huixing; Chen, Wei Ning; Chan-Park, Mary B.; Li, Chuan; Chan, Vincent

    2014-01-01

    During the past two decades, novel biomaterial scaffold for cell attachment and culture has been developed for applications in tissue engineering, biosensing and regeneration medicine. Tissue engineering of blood vessels remains a challenge owing to the complex three-layer histology involved. In order to engineer functional blood vessels, it is essential to recapitulate the characteristics of vascular smooth muscle cells (SMCs) inside the tunica media, which is known to be critical for vasoconstriction and vasodilation of the circulatory system. Until now, there has been a lack of understanding on the mechanotransduction of the SMC layer during the transformation from viable synthetic to quiescent contractile phenotypes. In this study, microfabricated arrays of discontinuous microwalls coated with fluorescence microbeads were developed to probe the mechanotransduction of the SMC layer. First, the system was exploited for stimulating the formation of a highly aligned orientation of SMCs in native tunica medium. Second, atomic force microscopy in combination with regression analysis was applied to measure the elastic modulus of a polyacrylamide gel layer coated on the discontinuous microwall arrays. Third, the conventional traction force assay for single cell measurement was extended for applications in three-dimensional cell aggregates. Then, the biophysical effects of discontinuous microwalls on the mechanotransduction of the SMC layer undergoing cell alignment were probed. Generally, the cooperative multiple cell–cell and cell–microwall interactions were accessed quantitatively by the newly developed assay with the aid of finite-element modelling. The results show that the traction forces of highly aligned cells lying in the middle region between two opposing microwalls were significantly lower than those lying adjacent to the microwalls. Moreover, the spatial distributions of Von Mises stress during the cell alignment process were dependent on the collective

  1. Desmin Mutation in the C-Terminal Domain Impairs Traction Force Generation in Myoblasts.

    PubMed

    Charrier, Elisabeth E; Asnacios, Atef; Milloud, Rachel; De Mets, Richard; Balland, Martial; Delort, Florence; Cardoso, Olivier; Vicart, Patrick; Batonnet-Pichon, Sabrina; Hénon, Sylvie

    2016-01-19

    The cytoskeleton plays a key role in the ability of cells to both resist mechanical stress and generate force, but the precise involvement of intermediate filaments in these processes remains unclear. We focus here on desmin, a type III intermediate filament, which is specifically expressed in muscle cells and serves as a skeletal muscle differentiation marker. By using several complementary experimental techniques, we have investigated the impact of overexpressing desmin and expressing a mutant desmin on the passive and active mechanical properties of C2C12 myoblasts. We first show that the overexpression of wild-type-desmin increases the overall rigidity of the cells, whereas the expression of a mutated E413K desmin does not. This mutation in the desmin gene is one of those leading to desminopathies, a subgroup of myopathies associated with progressive muscular weakness that are characterized by the presence of desmin aggregates and a disorganization of sarcomeres. We show that the expression of this mutant desmin in C2C12 myoblasts induces desmin network disorganization, desmin aggregate formation, and a small decrease in the number and total length of stress fibers. We finally demonstrate that expression of the E413K mutant desmin also alters the traction forces generation of single myoblasts lacking organized sarcomeres. PMID:26789769

  2. Multiphoton photochemical crosslinking-based fabrication of protein micropatterns with controllable mechanical properties for single cell traction force measurements

    NASA Astrophysics Data System (ADS)

    Tong, Ming Hui; Huang, Nan; Zhang, Wei; Zhou, Zhuo Long; Ngan, Alfonso Hing Wan; Du, Yanan; Chan, Barbara Pui

    2016-01-01

    Engineering 3D microstructures with predetermined properties is critical for stem cell niche studies. We have developed a multiphoton femtosecond laser-based 3D printing platform, which generates complex protein microstructures in minutes. Here, we used the platform to test a series of fabrication and reagent parameters in precisely controlling the mechanical properties of protein micropillars. Atomic force microscopy was utilized to measure the reduced elastic modulus of the micropillars, and transmission electron microscopy was used to visualize the porosity of the structures. The reduced elastic modulus of the micropillars associated positively and linearly with the scanning power. On the other hand, the porosity and pore size of the micropillars associated inversely and linearly with the scanning power and reagent concentrations. While keeping the elastic modulus constant, the stiffness of the micropillars was controlled by varying their height. Subsequently, the single cell traction forces of rabbit chondrocytes, human dermal fibroblasts, human mesenchymal stem cells, and bovine nucleus pulposus cells (bNPCs) were successfully measured by culturing the cells on micropillar arrays of different stiffness. Our results showed that the traction forces of all groups showed positive relationship with stiffness, and that the chondrocytes and bNPCs generated the highest and lowest traction forces, respectively.

  3. Multiphoton photochemical crosslinking-based fabrication of protein micropatterns with controllable mechanical properties for single cell traction force measurements.

    PubMed

    Tong, Ming Hui; Huang, Nan; Zhang, Wei; Zhou, Zhuo Long; Ngan, Alfonso Hing Wan; Du, Yanan; Chan, Barbara Pui

    2016-01-01

    Engineering 3D microstructures with predetermined properties is critical for stem cell niche studies. We have developed a multiphoton femtosecond laser-based 3D printing platform, which generates complex protein microstructures in minutes. Here, we used the platform to test a series of fabrication and reagent parameters in precisely controlling the mechanical properties of protein micropillars. Atomic force microscopy was utilized to measure the reduced elastic modulus of the micropillars, and transmission electron microscopy was used to visualize the porosity of the structures. The reduced elastic modulus of the micropillars associated positively and linearly with the scanning power. On the other hand, the porosity and pore size of the micropillars associated inversely and linearly with the scanning power and reagent concentrations. While keeping the elastic modulus constant, the stiffness of the micropillars was controlled by varying their height. Subsequently, the single cell traction forces of rabbit chondrocytes, human dermal fibroblasts, human mesenchymal stem cells, and bovine nucleus pulposus cells (bNPCs) were successfully measured by culturing the cells on micropillar arrays of different stiffness. Our results showed that the traction forces of all groups showed positive relationship with stiffness, and that the chondrocytes and bNPCs generated the highest and lowest traction forces, respectively. PMID:26817674

  4. Multiphoton photochemical crosslinking-based fabrication of protein micropatterns with controllable mechanical properties for single cell traction force measurements

    PubMed Central

    Tong, Ming Hui; Huang, Nan; Zhang, Wei; Zhou, Zhuo Long; Ngan, Alfonso Hing Wan; Du, Yanan; Chan, Barbara Pui

    2016-01-01

    Engineering 3D microstructures with predetermined properties is critical for stem cell niche studies. We have developed a multiphoton femtosecond laser-based 3D printing platform, which generates complex protein microstructures in minutes. Here, we used the platform to test a series of fabrication and reagent parameters in precisely controlling the mechanical properties of protein micropillars. Atomic force microscopy was utilized to measure the reduced elastic modulus of the micropillars, and transmission electron microscopy was used to visualize the porosity of the structures. The reduced elastic modulus of the micropillars associated positively and linearly with the scanning power. On the other hand, the porosity and pore size of the micropillars associated inversely and linearly with the scanning power and reagent concentrations. While keeping the elastic modulus constant, the stiffness of the micropillars was controlled by varying their height. Subsequently, the single cell traction forces of rabbit chondrocytes, human dermal fibroblasts, human mesenchymal stem cells, and bovine nucleus pulposus cells (bNPCs) were successfully measured by culturing the cells on micropillar arrays of different stiffness. Our results showed that the traction forces of all groups showed positive relationship with stiffness, and that the chondrocytes and bNPCs generated the highest and lowest traction forces, respectively. PMID:26817674

  5. Plectin-containing, centrally localized focal adhesions exert traction forces in primary lung epithelial cells

    PubMed Central

    Eisenberg, Jessica L.; Beaumont, Kristin G.; Takawira, Desire; Hopkinson, Susan B.; Mrksich, Milan; Budinger, G. R. Scott; Jones, Jonathan C. R.

    2013-01-01

    Summary Receptor clustering upon cell attachment to the substrate induces assembly of cytoplasmic protein complexes termed focal adhesions (FAs), which connect, albeit indirectly, the extracellular matrix to the cytoskeleton. A subset of cultured primary alveolar epithelial cells (AEC) display a unique pattern of vinculin/paxillin/talin-rich FAs in two concentric circles when cultured on glass and micropatterned substrates: one ring of FAs located at the cell periphery (pFAs), and another FA ring located centrally in the cell (cFAs). Unusually, cFAs associate with an aster-like actin array as well as keratin bundles. Moreover, cFAs show rapid paxillin turnover rates following fluorescence recovery after photobleaching and exert traction forces similar to those generated by FAs at the cell periphery. The plakin protein plectin localizes to cFAs and is normally absent from pFAs, whereas tensin, a marker of mature/fibrillar adhesions, is found in both cFAs and pFAs. In primary AEC in which plectin expression is depleted, cFAs are largely absent, with an attendant reorganization of both the keratin and actin cytoskeletons. We suggest that the mechanical environment in the lung gives rise to the assembly of unconventional FAs in AEC. These FAs not only show a distinctive arrangement, but also possess unique compositional and functional properties. PMID:23750011

  6. Characterization of Intracellular Streaming and Traction Forces in Migrating Physarum Plasmodia

    NASA Astrophysics Data System (ADS)

    Zhang, Shun; Del Alamo, Juan C.; Guy, Robert D.; Lasheras, Juan C.

    2012-11-01

    Physarum plasmodium is a model organism for cell migration that exhibits fast intracellular streaming. Motile amoeboid physarum plasmodia were obtained from dish cultures of Physarum Polycephalum, a slime mold that inhabits shady cool moist areas in the wild, such as decaying vegetable material. The migrating amoebae were obtained by cutting successively smaller pieces from the growing tips of the cultured parent mold, and their size ranged 0.2 to 0.5 mm. Single amoebae were seeded and let adhere on flexible polyacrilamide gels that were functionalized with collagen, contained 0.2-micron fluorescent beads, and were embedded in an aqueous medium. Soon after adhering to the gel, the amoeabe began crawling at about 1mm/hr. Joint time-lapse sequences of intracellular streaming and gel deformation were acquired respectively in the bright and fluorescent fields of a confocal microscope at 20X magnification. These images were analyzed using particle-tracking algorithms, and the traction stresses applied by the amoebae on the surface were computed by solving the elastostatic equation for the gel using the measured bead displacements as boundary conditions. These measurements provide, for the first time, a joint characterization of intracellular mass transport and the forces driving this transport in motile amoeboid cells.

  7. A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy

    DOE PAGESBeta

    Solares, Santiago D.

    2015-11-26

    This study introduces a quasi-3-dimensional (Q3D) viscoelastic model and software tool for use in atomic force microscopy (AFM) simulations. The model is based on a 2-dimensional array of standard linear solid (SLS) model elements. The well-known 1-dimensional SLS model is a textbook example in viscoelastic theory but is relatively new in AFM simulation. It is the simplest model that offers a qualitatively correct description of the most fundamental viscoelastic behaviors, namely stress relaxation and creep. However, this simple model does not reflect the correct curvature in the repulsive portion of the force curve, so its application in the quantitative interpretationmore » of AFM experiments is relatively limited. In the proposed Q3D model the use of an array of SLS elements leads to force curves that have the typical upward curvature in the repulsive region, while still offering a very low computational cost. Furthermore, the use of a multidimensional model allows for the study of AFM tips having non-ideal geometries, which can be extremely useful in practice. Examples of typical force curves are provided for single- and multifrequency tappingmode imaging, for both of which the force curves exhibit the expected features. Lastly, a software tool to simulate amplitude and phase spectroscopy curves is provided, which can be easily modified to implement other controls schemes in order to aid in the interpretation of AFM experiments.« less

  8. A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy

    SciTech Connect

    Solares, Santiago D.

    2015-11-26

    This study introduces a quasi-3-dimensional (Q3D) viscoelastic model and software tool for use in atomic force microscopy (AFM) simulations. The model is based on a 2-dimensional array of standard linear solid (SLS) model elements. The well-known 1-dimensional SLS model is a textbook example in viscoelastic theory but is relatively new in AFM simulation. It is the simplest model that offers a qualitatively correct description of the most fundamental viscoelastic behaviors, namely stress relaxation and creep. However, this simple model does not reflect the correct curvature in the repulsive portion of the force curve, so its application in the quantitative interpretation of AFM experiments is relatively limited. In the proposed Q3D model the use of an array of SLS elements leads to force curves that have the typical upward curvature in the repulsive region, while still offering a very low computational cost. Furthermore, the use of a multidimensional model allows for the study of AFM tips having non-ideal geometries, which can be extremely useful in practice. Examples of typical force curves are provided for single- and multifrequency tappingmode imaging, for both of which the force curves exhibit the expected features. Lastly, a software tool to simulate amplitude and phase spectroscopy curves is provided, which can be easily modified to implement other controls schemes in order to aid in the interpretation of AFM experiments.

  9. A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy

    PubMed Central

    2015-01-01

    Summary This paper introduces a quasi-3-dimensional (Q3D) viscoelastic model and software tool for use in atomic force microscopy (AFM) simulations. The model is based on a 2-dimensional array of standard linear solid (SLS) model elements. The well-known 1-dimensional SLS model is a textbook example in viscoelastic theory but is relatively new in AFM simulation. It is the simplest model that offers a qualitatively correct description of the most fundamental viscoelastic behaviors, namely stress relaxation and creep. However, this simple model does not reflect the correct curvature in the repulsive portion of the force curve, so its application in the quantitative interpretation of AFM experiments is relatively limited. In the proposed Q3D model the use of an array of SLS elements leads to force curves that have the typical upward curvature in the repulsive region, while still offering a very low computational cost. Furthermore, the use of a multidimensional model allows for the study of AFM tips having non-ideal geometries, which can be extremely useful in practice. Examples of typical force curves are provided for single- and multifrequency tapping-mode imaging, for both of which the force curves exhibit the expected features. Finally, a software tool to simulate amplitude and phase spectroscopy curves is provided, which can be easily modified to implement other controls schemes in order to aid in the interpretation of AFM experiments. PMID:26734515

  10. High-throughput and non-destructive sidewall roughness measurement using 3-dimensional atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Hua, Yueming; Buenviaje-Coggins, Cynthia; Lee, Yong-ha; Park, Sang-il

    2012-03-01

    As the feature size of the semiconductor device is becoming increasingly smaller and the transistor has become three-dimensional (e.g. Fin-FET structure), a simple Line Edge Roughness (LER) is no longer sufficient for characterizing these devices. Sidewall Roughness (SWR) is now the more proper metric for these metrology applications. However, current metrology technologies, such as SEM and OCD, provide limited information on the sidewall of such small structures. The subject of this study is the sidewall roughness measurement with a three-dimensional Atomic Force Microscopy (AFM) using tilted Z scanner. This 3D AFM is based on a decoupled XY and Z scanning configuration, in which the Z scanner can be intentionally tilted to the side. A sharp conical tip is typically used for imaging, which provides high resolution capability on both the flat surfaces (top and bottom) and the steep sidewalls.

  11. Agent-based modeling traction force mediated compaction of cell-populated collagen gels using physically realistic fibril mechanics.

    PubMed

    Reinhardt, James W; Gooch, Keith J

    2014-02-01

    Agent-based modeling was used to model collagen fibrils, composed of a string of nodes serially connected by links that act as Hookean springs. Bending mechanics are implemented as torsional springs that act upon each set of three serially connected nodes as a linear function of angular deflection about the central node. These fibrils were evaluated under conditions that simulated axial extension, simple three-point bending and an end-loaded cantilever. The deformation of fibrils under axial loading varied <0.001% from the analytical solution for linearly elastic fibrils. For fibrils between 100 μm and 200 μm in length experiencing small deflections, differences between simulated deflections and their analytical solutions were <1% for fibrils experiencing three-point bending and <7% for fibrils experiencing cantilever bending. When these new rules for fibril mechanics were introduced into a model that allowed for cross-linking of fibrils to form a network and the application of cell traction force, the fibrous network underwent macroscopic compaction and aligned between cells. Further, fibril density increased between cells to a greater extent than that observed macroscopically and appeared similar to matrical tracks that have been observed experimentally in cell-populated collagen gels. This behavior is consistent with observations in previous versions of the model that did not allow for the physically realistic simulation of fibril mechanics. The significance of the torsional spring constant value was then explored to determine its impact on remodeling of the simulated fibrous network. Although a stronger torsional spring constant reduced the degree of quantitative remodeling that occurred, the inclusion of torsional springs in the model was not necessary for the model to reproduce key qualitative aspects of remodeling, indicating that the presence of Hookean springs is essential for this behavior. These results suggest that traction force mediated matrix

  12. Integrin-beta3 clusters recruit clathrin-mediated endocytic machinery in the absence of traction force

    PubMed Central

    Yu, Cheng-han; Rafiq, Nisha Bte Mohd; Cao, Fakun; Zhou, Yuhuan; Krishnasamy, Anitha; Biswas, Kabir Hassan; Ravasio, Andrea; Chen, Zhongwen; Wang, Yu-Hsiu; Kawauchi, Keiko; Jones, Gareth E.; Sheetz, Michael P.

    2015-01-01

    The turnover of integrin receptors is critical for cell migration and adhesion dynamics. Here we find that force development at integrins regulates adaptor protein recruitment and endocytosis. Using mobile RGD (Arg-Gly-Asp) ligands on supported lipid membranes (RGD membranes) and rigid RGD ligands on glass (RGD-glass), we find that matrix force-dependent integrin signals block endocytosis. Dab2, an adaptor protein of clathrin-mediated endocytosis, is not recruited to activated integrin-beta3 clusters on RGD-glass; however, it is recruited to integrin-mediated adhesions on RGD membranes. Further, when force generation is inhibited on RGD-glass, Dab2 binds to integrin-beta3 clusters. Dab2 binding to integrin-beta3 excludes other adhesion-related adaptor proteins, such as talin. The clathrin-mediated endocytic machinery combines with Dab2 to facilitate the endocytosis of RGD-integrin-beta3 clusters. From these observations, we propose that loss of traction force on ligand-bound integrin-beta3 causes recruitment of Dab2/clathrin, resulting in endocytosis of integrins. PMID:26507506

  13. Cell Origami: Self-Folding of Three-Dimensional Cell-Laden Microstructures Driven by Cell Traction Force

    PubMed Central

    Kuribayashi-Shigetomi, Kaori; Onoe, Hiroaki; Takeuchi, Shoji

    2012-01-01

    This paper describes a method of generating three-dimensional (3D) cell-laden microstructures by applying the principle of origami folding technique and cell traction force (CTF). We harness the CTF as a biological driving force to fold the microstructures. Cells stretch and adhere across multiple microplates. Upon detaching the microplates from a substrate, CTF causes the plates to lift and fold according to a prescribed pattern. This self-folding technique using cells is highly biocompatible and does not involve special material requirements for the microplates and hinges to induce folding. We successfully produced various 3D cell-laden microstructures by just changing the geometry of the patterned 2D plates. We also achieved mass-production of the 3D cell-laden microstructures without causing damage to the cells. We believe that our methods will be useful for biotechnology applications that require analysis of cells in 3D configurations and for self-assembly of cell-based micro-medical devices. PMID:23251426

  14. Characterization of cellular traction forces at the single-molecule level

    NASA Astrophysics Data System (ADS)

    Dunn, Alexander

    2013-03-01

    The ability of cells to generate and respond to mechanical cues is an essential aspect of stem cell differentiation, embryonic development, and our senses of touch and hearing. However, our understanding of the roles of mechanical force in cell biology remains in its infancy, due largely to a lack of tools that measure the forces generated by living cells at the molecular scale. Here we describe a new technique termed Molecular Force Microscopy (MFM) that visualizes the forces exerted by single cellular adhesion molecules with nm, pN, and sub-second resolutions. MFM uses novel FRET-based molecular tension sensors that bind to a glass coverslip and present a binding site for integrins, a ubiquitous class of cell adhesion proteins. Cell-generated forces stretch the MFM sensor molecules, resulting in decreased FRET with increasing load that can be imaged at the single-molecule level. Human foreskin fibroblasts adhere to surfaces functionalized with the MFM probes and develop robust focal adhesions. FRET values measured using MFM indicate forces of between 1 and 4 pN per integrin, thus providing the first direct measurement of the tension per integrin molecule necessary to form stable adhesions. The relatively narrow force distribution suggests that mechanical tension is subject to exquisite feedback and control at the molecular level.

  15. Myelin-associated proteins block the migration of olfactory ensheathing cells: an in vitro study using single-cell tracking and traction force microscopy.

    PubMed

    Nocentini, Sara; Reginensi, Diego; Garcia, Simón; Carulla, Patricia; Moreno-Flores, María Teresa; Wandosell, Francisco; Trepat, Xavier; Bribian, Ana; del Río, José A

    2012-05-01

    Newly generated olfactory receptor axons grow from the peripheral to the central nervous system aided by olfactory ensheathing cells (OECs). Thus, OEC transplantation has emerged as a promising therapy for spinal cord injuries and for other neural diseases. However, these cells do not present a uniform population, but instead a functionally heterogeneous population that exhibits a variety of responses including adhesion, repulsion, and crossover during cell-cell and cell-matrix interactions. Some studies report that the migratory properties of OECs are compromised by inhibitory molecules and potentiated by chemical gradients. Here, we demonstrated that rodent OECs express all the components of the Nogo receptor complex and that their migration is blocked by myelin. Next, we used cell tracking and traction force microscopy to analyze OEC migration and its mechanical properties over myelin. Our data relate the decrease of traction force of OEC with lower migratory capacity over myelin, which correlates with changes in the F-actin cytoskeleton and focal adhesion distribution. Lastly, OEC traction force and migratory capacity is enhanced after cell incubation with the Nogo receptor inhibitor NEP1-40. PMID:22205212

  16. Micropillar displacements by cell traction forces are mechanically correlated with nuclear dynamics

    SciTech Connect

    Li, Qingsen; Makhija, Ekta; Hameed, F.M.; Shivashankar, G.V.

    2015-05-29

    Cells sense physical cues at the level of focal adhesions and transduce them to the nucleus by biochemical and mechanical pathways. While the molecular intermediates in the mechanical links have been well studied, their dynamic coupling is poorly understood. In this study, fibroblast cells were adhered to micropillar arrays to probe correlations in the physical coupling between focal adhesions and nucleus. For this, we used novel imaging setup to simultaneously visualize micropillar deflections and EGFP labeled chromatin structure at high spatial and temporal resolution. We observed that micropillar deflections, depending on their relative positions, were positively or negatively correlated to nuclear and heterochromatin movements. Our results measuring the time scales between micropillar deflections and nucleus centroid displacement are suggestive of a strong elastic coupling that mediates differential force transmission to the nucleus. - Highlights: • Correlation between focal adhesions and nucleus studied using novel imaging setup. • Micropillar and nuclear displacements were measured at high resolution. • Correlation timescales show strong elastic coupling between cell edge and nucleus.

  17. The Effects of Different Miniscrew Thread Designs and Force Directions on Stress Distribution by 3-dimensional Finite Element Analysis

    PubMed Central

    Fattahi, Hamidreza; Ajami, Shabnam; Nabavizadeh Rafsanjani, Ali

    2015-01-01

    Statement of the Problem The use of miniscrew as an absolute anchorage device in clinical orthodontics is growing increasingly. Many attempts have been made to reduce the size, to improve the design, and to increase the stability of miniscrew. Purpose The purpose of this study was to determine the effects of different thread shapes and force directions of orthodontic miniscrew on stress distribution in the supporting bone structure. Materials and Method A three-dimensional finite element analysis was used. A 200-cN force in three angles (0°, 45°, and 90°) was applied on the head of the miniscrew. The stress distribution between twelve thread shapes was investigated as categorized in four main groups; buttress, reverse buttress, square, and V-shape. Results Stress distribution was not significantly different among different thread shapes. The maximum amount of bone stress at force angles 0°, 45°, and 90° were 38.90, 30.57 and 6.62 MPa, respectively. Analyzing the von Mises stress values showed that in all models, the maximum stress was concentrated on the lowest diameter of the shank, especially the part that was in the soft tissue and cervical cortical bone regions. Conclusion There was no relation between thread shapes and von Mises stress distribution in the bone; however, different force angles could affect the von Mises stress in the bone and miniscrew. PMID:26636123

  18. Cell-generated traction forces and the resulting matrix deformation modulate microvascular alignment and growth during angiogenesis

    PubMed Central

    Underwood, Clayton J.; Edgar, Lowell T.; Hoying, James B.

    2014-01-01

    The details of the mechanical factors that modulate angiogenesis remain poorly understood. Previous in vitro studies of angiogenesis using microvessel fragments cultured within collagen constructs demonstrated that neovessel alignment can be induced via mechanical constraint of the boundaries (i.e., boundary conditions). The objective of this study was to investigate the role of mechanical boundary conditions in the regulation of angiogenic alignment and growth in an in vitro model of angiogenesis. Angiogenic microvessels within three-dimensional constructs were subjected to different boundary conditions, thus producing different stress and strain fields during growth. Neovessel outgrowth and orientation were quantified from confocal image data after 6 days. Vascularity and branching decreased as the amount of constraint imposed on the culture increased. In long-axis constrained hexahedral constructs, microvessels aligned parallel to the constrained axis. In contrast, constructs that were constrained along the short axis had random microvessel orientation. Finite element models were used to simulate the contraction of gels under the various boundary conditions and to predict the local strain field experienced by microvessels. Results from the experiments and simulations demonstrated that microvessels aligned perpendicular to directions of compressive strain. Alignment was due to anisotropic deformation of the matrix from cell-generated traction forces interacting with the mechanical boundary conditions. These findings demonstrate that boundary conditions and thus the effective stiffness of the matrix regulate angiogenesis. This study offers a potential explanation for the oriented vascular beds that occur in native tissues and provides the basis for improved control of tissue vascularization in both native tissues and tissue-engineered constructs. PMID:24816262

  19. Lateral traction

    MedlinePlus

    ... be used to treat or reduce any joint dislocation or bone fracture by applying tension to the leg or arm with weights and pulleys to realign the bone. For example, it may be used to help keep a dislocated hip within the hip socket while it heals. Traction ...

  20. Open coil traction system.

    PubMed

    Vibhute, Pavankumar Janardan

    2012-01-01

    Sliding mechanics have become a popular method for space closure, with the development of preadjusted edgewise appliances. Furthermore, various space closing auxiliaries have been developed and extensively evaluated for their clinical efficiency. Their effectiveness is enhanced with optimum force magnitude and low load deflection rate/force decay. With the advent of nickel-titanium (Ni-Ti) springs in orthodontics, load deflection rates have been markedly reduced. To use Ni-Ti springs, clinicians have to depend upon prefabricated closed coil springs. The open coil traction system, or open coil retraction spring, is developed utilizing Ni-Ti open coil springs for orthodontic space closure. This article describes the fabrication and clinical application of the open coil traction system, which has a number of advantages. It sustains a low load deflection rate with optimum force magnitude, and its design is adjustable for a desired length and force level. It is fail-safe for both activation and deactivation (ie, it cannot be overactivated, and the decompression limit of the open coil is controlled by the operator). The open coil traction system can be offset from the mucosa to help reduce soft tissue impingement. PMID:22567645

  1. Traction behavior of two traction lubricants

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Rohn, D. A.

    1983-01-01

    In the analysis of rolling-sliding concentrated contacts, such as gears, bearings and traction drives, the traction characteristics of the lubricant are of prime importance. The elastic shear modulus and limiting shear stress properties of the lubricant dictate the traction/slip characteristics and power loss associated with an EHD contact undergoing slip and/or spin. These properties can be deducted directly from the initial slope m and maximum traction coefficient micron of an experimental traction curve. In this investigation, correlation equations are presented to predict m and micron for two modern traction fluids based on the regression analysis of 334 separate traction disk machine experiments. The effects of contact pressure, temperature, surface velocity, ellipticity ratio are examined. Problems in deducing lubricant shear moduli from disk machine tests are discussed.

  2. Fibroblast traction as a mechanism for collagen morphogenesis

    NASA Astrophysics Data System (ADS)

    Harris, Albert K.; Stopak, David; Wild, Patricia

    1981-03-01

    To make visible the traction forces exerted by individual cells, we have previously developed a method of culturing them on thin distortable sheets of silicone rubber1. We have now used this method to compare the forces exerted by various differentiated cell types and have examined the effects of cellular traction on re-precipitated collagen matrices. We find that the strength of cellular traction differs greatly between cell types and this traction is paradoxically weakest in the most mobile and invasive cells (leukocytes and nerve growth cones). Untransformed fibroblasts exert forces very much larger than those actually needed for locomotion. This strong traction distorts collagen gels dramatically, creating patterns similar to tendons and organ capsules. We propose that this morphogenetic rearrangement of extracellular matrices is the primary function of fibroblast traction and explains its excessive strength.

  3. Traction in smooth muscle cells varies with cell spreading

    NASA Technical Reports Server (NTRS)

    Tolic-Norrelykke, Iva Marija; Wang, Ning

    2005-01-01

    Changes in cell shape regulate cell growth, differentiation, and apoptosis. It has been suggested that the regulation of cell function by the cell shape is a result of the tension in the cytoskeleton and the distortion of the cell. Here we explore the association between cell-generated mechanical forces and the cell morphology. We hypothesized that the cell contractile force is associated with the degree of cell spreading, in particular with the cell length. We measured traction fields of single human airway smooth muscle cells plated on a polyacrylamide gel, in which fluorescent microbeads were embedded to serve as markers of gel deformation. The traction exerted by the cells at the cell-substrate interface was determined from the measured deformation of the gel. The traction was measured before and after treatment with the contractile agonist histamine, or the relaxing agonist isoproterenol. The relative increase in traction induced by histamine was negatively correlated with the baseline traction. On the contrary, the relative decrease in traction due to isoproterenol was independent of the baseline traction, but it was associated with cell shape: traction decreased more in elongated than in round cells. Maximum cell width, mean cell width, and projected area of the cell were the parameters most tightly coupled to both baseline and histamine-induced traction in this study. Wide and well-spread cells exerted larger traction than slim cells. These results suggest that cell contractility is controlled by cell spreading.

  4. Effects of gape and tooth position on bite force and skull stress in the dingo (Canis lupus dingo) using a 3-dimensional finite element approach.

    PubMed

    Bourke, Jason; Wroe, Stephen; Moreno, Karen; McHenry, Colin; Clausen, Philip

    2008-01-01

    Models of the mammalian jaw have predicted that bite force is intimately linked to jaw gape and to tooth position. Despite widespread use, few empirical studies have provided evidence to validate these models in non-human mammals and none have considered the influence of gape angle on the distribution of stress. Here using a multi-property finite element (FE) model of Canis lupus dingo, we examined the influence of gape angle and bite point on both bite force and cranial stress. Bite force data in relation to jaw gape and along the tooth row, are in broad agreement with previously reported results. However stress data showed that the skull of C. l. dingo is mechanically suited to withstand stresses at wide gapes; a result that agreed well with previously held views regarding carnivoran evolution. Stress data, combined with bite force information, suggested that there is an optimal bite angle of between 25 degrees and 35 degrees in C. l. dingo. The function of these rather small bite angles remains unclear. PMID:18493603

  5. Principles of traction.

    PubMed

    Osmond, T

    1999-02-01

    Traction has been the mainstay of orthopaedic management for thousands of years, with its use recorded by the Aztecs and ancient Egyptians. In more recent times, however, the advances in surgical reductions of fractures and muscutoskeletal disruptions, coupled with the economic imperatives of reducing hospital bed stay days has seen a reduction the use of prolonged periods of traction. PMID:10205405

  6. Design of traction drives

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Zaretsky, E. V.

    1985-01-01

    Traction drives are among the simplest of all speed-changing mechanisms. Because of their simplicity and their ability to smoothly and continuously adjust speed, they are excellent choices for many drive system applications. They have been used in industrial service for more than 100 years. Today's traction drives have power capacities which rival the best gear and belt drives due to modern traction fluids and highly fatigue-resistant bearing steels. This report summarizes methods to analyze and size traction drives. Lubrication principles, contact kinematics, stress, fatigue life, and performance prediction methods are presented. The effects of the lubricant's traction characteristics on life and power loss are discussed. An example problem is given which illustrates the effects of spin on power loss. Loading mechanism design and the design of nonlubricated friction wheels and rings are also treated.

  7. Sizing criterial for traction drives

    NASA Technical Reports Server (NTRS)

    Rohn, D. A.; Loewenthal, S. H.; Coy, J. J.

    1983-01-01

    A simplified traction drive fatigue analysis which was derived from the Lundberg-Palmgren theory is measured and the effects of rotational speed, multiplicity of contacts, and variation in the available traction coefficient on traction drive system life, size, and power capacity was investigated. Simplified equations are provided for determining the 90% survival life rating of steel traction drive contacts of arbitrary geometry. References to life modifying factors for material, lubrication, and traction will be made.

  8. Regression analysis of traction characteristics of traction fluids

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Rohn, D. A.

    1983-01-01

    Traction data for Santotrac 50 and TDF-88 over a wide range of operating conditions were analyzed. An eight term correlation equation to predict the maximum traction coefficient and a six term correlation equation to predict the initial slope of the traction curve were developed. The slope correlation was corrected for size effect considering the compliance of the disks. The effects of different operating conditions on the traction performance of each traction fluid were studied. Both fluids exhibited a loss in traction with increases in spin, but the losses with the TDF-88 fluid were not as severe as those with Santotrac 50. Overall, both fluids exhibited similar performance, showing an increase in traction with contact pressure up to about 2.0 GPa, and a reduction in traction with higher surface speeds up to about 100 m/sec. The apparent stiffness of the traction contact, that is, film disk combination, increases with contact pressure and decreases with speed.

  9. Traction prediction of a smooth rigid wheel in soil using coupled eulerian-lagrangian analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Traction is an important performance requirement for a tire and is the force that propels a vehicle forward. Accurate traction prediction is important in reducing development cycle time and improving mechanistic understanding of tire traction performance. On a rigid surface like a paved road, trac...

  10. Liposome adhesion generates traction stress

    NASA Astrophysics Data System (ADS)

    Murrell, Michael P.; Voituriez, Raphaël; Joanny, Jean-François; Nassoy, Pierre; Sykes, Cécile; Gardel, Margaret L.

    2014-02-01

    Mechanical forces generated by cells modulate global shape changes required for essential life processes, such as polarization, division and spreading. Although the contribution of the cytoskeleton to cellular force generation is widely recognized, the role of the membrane is considered to be restricted to passively transmitting forces. Therefore, the mechanisms by which the membrane can directly contribute to cell tension are overlooked and poorly understood. To address this, we directly measure the stresses generated during liposome adhesion. We find that liposome spreading generates large traction stresses on compliant substrates. These stresses can be understood as the equilibration of internal, hydrostatic pressures generated by the enhanced membrane tension built up during adhesion. These results underscore the role of membranes in the generation of mechanical stresses on cellular length scales and that the modulation of hydrostatic pressure due to membrane tension and adhesion can be channelled to perform mechanical work on the environment.

  11. Towards Single Cell Traction Microscopy within 3D Collagen Matrices

    PubMed Central

    Hall, Matthew S.; Long, Rong; Feng, Xinzeng; Huang, YuLing; Hui, Chung-Yuen; Wu, Mingming

    2013-01-01

    Mechanical interaction between the cell and its extracellular matrix (ECM) regulates cellular behaviors, including proliferation, differentiation, adhesion, and migration. Cells require the three dimensional (3D) architectural support of the ECM to perform physiologically realistic functions. However, current understanding of cell-ECM and cell-cell mechanical interactions is largely derived from 2D cell traction force microscopy, in which cells are cultured on a flat substrate. 3D cell traction microscopy is emerging for mapping traction fields of single animal cells embedded in either synthetic or natively derived fibrous gels. We discuss here the development of 3D cell traction microscopy, its current limitations, and perspectives on the future of this technology. Emphasis is placed on strategies for applying 3D cell traction microscopy to individual tumor cells migration within collagen gels. PMID:23806281

  12. Toward single cell traction microscopy within 3D collagen matrices

    SciTech Connect

    Hall, Matthew S.; Long, Rong; Feng, Xinzeng; Huang, YuLing; Hui, Chung-Yuen; Wu, Mingming

    2013-10-01

    Mechanical interaction between the cell and its extracellular matrix (ECM) regulates cellular behaviors, including proliferation, differentiation, adhesion, and migration. Cells require the three-dimensional (3D) architectural support of the ECM to perform physiologically realistic functions. However, current understanding of cell–ECM and cell–cell mechanical interactions is largely derived from 2D cell traction force microscopy, in which cells are cultured on a flat substrate. 3D cell traction microscopy is emerging for mapping traction fields of single animal cells embedded in either synthetic or natively derived fibrous gels. We discuss here the development of 3D cell traction microscopy, its current limitations, and perspectives on the future of this technology. Emphasis is placed on strategies for applying 3D cell traction microscopy to individual tumor cell migration within collagen gels. - Highlights: • Review of the current state of the art in 3D cell traction force microscopy. • Bulk and micro-characterization of remodelable fibrous collagen gels. • Strategies for performing 3D cell traction microscopy within collagen gels.

  13. Traction calculations and design data for two traction fluids

    NASA Technical Reports Server (NTRS)

    Tevaarwerk, J. L.

    1983-01-01

    The rheological properties of the fluid under these certain conditions which precludes the use of most of the conventional instruments for steady state measurement were studied. The only suitable type of instrument is a disk machine where most of the conditions are the same of similar to those in traction drives. From the resulting traction tests, certain models are inferred. To the designer of traction drives, the traction behavior of the fluid under the severe conditions is of utmost importance because of the direct influence that it has on the efficiency, size, and life of a given drive.

  14. Patchy Traction Alopecia Mimicking Areata

    PubMed Central

    Barbosa, Aline Blanco; Donati, Aline; Valente, Neusa S; Romiti, Ricardo

    2015-01-01

    Acute traction alopecia is a diagnostic challenge when the external factor is not suspected or admitted. We report two female patients with non-scarring patchy alopecia resulting from traction of video-electroencephalogram electrodes in which the clinical diagnosis of alopecia areata was suspected. Associated diffuse hair disorders might be implicated in these cases. The correct diagnosis of traction alopecia is important in order to avoid unnecessary treatments. PMID:26903751

  15. Advances in traction drive technology

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Anderson, N. E.; Rohn, D. A.

    1983-01-01

    Traction drives are traced from early uses as main transmissions in automobiles at the turn of the century to modern, high-powered traction drives capable of transmitting hundreds of horsepower. Recent advances in technology are described which enable today's traction drive to be a serious candidate for off-highway vehicles and helicopter applications. Improvements in materials, traction fluids, design techniques, power loss and life prediction methods will be highlighted. Performance characteristics of the Nasvytis fixed-ratio drive are given. Promising future drive applications, such as helicopter main transmissions and servo-control positioning mechanisms are also addressed.

  16. Traction Stresses Exerted by Adherent Cells: From Angiogenesis to Metastasis

    NASA Astrophysics Data System (ADS)

    Reinhart-King, Cynthia

    2010-03-01

    Cells exert traction stresses against their substrate that mediate their ability to sense the mechanical properties of their microenvironment. These same forces mediate cell adhesion, migration and the formation of stable cell-cell contacts during tissue formation. In this talk, I will present our data on the traction stresses generated by endothelial cells and metastatic breast cancer cells focused on understanding the processes of angiogenesis and metastasis, respectively. In the context of capillary formation, our data indicate that the mechanics of the substrate play a critical role in establishing endothelial cell-cell contacts. On more compliant substrates, endothelial cell shape and traction stresses polarize and promote the formation of stable cell-cell contacts. On stiffer substrates, traction stresses are less polarized and cell connectivity is disrupted. These data indicate that the mechanical properties of the microenvironment may drive cell connectivity and the formation of stable cell-cell contacts through the reorientation of traction stresses. In our studies of metastatic cell migration, we have found that traction stresses increase with increasing metastatic potential. We investigated three lines of varying metastatic potential (MCF10A, MCF7 and MDAMB231). MDAMB231, which are the most invasive, exert the most significant forces as measured by Traction Force Microscopy. These data present the possibility that cellular traction stress generation aids in the ability of metastatic cells to migrate through the matrix-dense tumor microenvironment. Such measurements are integral to link the mechanical and chemical microenvironment with the resulting response of the cell in health and disease.

  17. Three-Dimensional Reflectance Traction Microscopy

    PubMed Central

    Jones, Christopher A. R.; Groves, Nicholas Scott; Sun, Bo

    2016-01-01

    Cells in three-dimensional (3D) environments exhibit very different biochemical and biophysical phenotypes compared to the behavior of cells in two-dimensional (2D) environments. As an important biomechanical measurement, 2D traction force microscopy can not be directly extended into 3D cases. In order to quantitatively characterize the contraction field, we have developed 3D reflectance traction microscopy which combines confocal reflection imaging and partial volume correlation postprocessing. We have measured the deformation field of collagen gel under controlled mechanical stress. We have also characterized the deformation field generated by invasive breast cancer cells of different morphologies in 3D collagen matrix. In contrast to employ dispersed tracing particles or fluorescently-tagged matrix proteins, our methods provide a label-free, computationally effective strategy to study the cell mechanics in native 3D extracellular matrix. PMID:27304456

  18. Advanced Integrated Traction System

    SciTech Connect

    Greg Smith; Charles Gough

    2011-08-31

    The United States Department of Energy elaborates the compelling need for a commercialized competitively priced electric traction drive system to proliferate the acceptance of HEVs, PHEVs, and FCVs in the market. The desired end result is a technically and commercially verified integrated ETS (Electric Traction System) product design that can be manufactured and distributed through a broad network of competitive suppliers to all auto manufacturers. The objectives of this FCVT program are to develop advanced technologies for an integrated ETS capable of 55kW peak power for 18 seconds and 30kW of continuous power. Additionally, to accommodate a variety of automotive platforms the ETS design should be scalable to 120kW peak power for 18 seconds and 65kW of continuous power. The ETS (exclusive of the DC/DC Converter) is to cost no more than $660 (55kW at $12/kW) to produce in quantities of 100,000 units per year, should have a total weight less than 46kg, and have a volume less than 16 liters. The cost target for the optional Bi-Directional DC/DC Converter is $375. The goal is to achieve these targets with the use of engine coolant at a nominal temperature of 105C. The system efficiency should exceed 90% at 20% of rated torque over 10% to 100% of maximum speed. The nominal operating system voltage is to be 325V, with consideration for higher voltages. This project investigated a wide range of technologies, including ETS topologies, components, and interconnects. Each technology and its validity for automotive use were verified and then these technologies were integrated into a high temperature ETS design that would support a wide variety of applications (fuel cell, hybrids, electrics, and plug-ins). This ETS met all the DOE 2010 objectives of cost, weight, volume and efficiency, and the specific power and power density 2015 objectives. Additionally a bi-directional converter was developed that provides charging and electric power take-off which is the first step

  19. Ac traction gets on track

    SciTech Connect

    O`Connor, L.

    1995-09-01

    This article describes inverter-based ac traction systems which give freight locomotives greater adhesion, pulling power, and braking capacity. In the 1940s, dc traction replaced the steam engine as a source of train propulsion, and it has ruled the freight transportation industry ever since. But now, high-performance ac-traction systems, with their unprecedented levels of pulling power and adhesion, are becoming increasingly common on America`s freight railroads. In thousands of miles of demonstration tests, today`s ac-traction systems have outperformed traditional dc-motor driven systems. Major railroad companies are convinced enough of the benefits of ac traction to have integrated it into their freight locomotives.

  20. Two distinct actin networks mediate traction oscillations to confer mechanosensitivity of focal adhesions

    NASA Astrophysics Data System (ADS)

    Wu, Zhanghan; Plotnikov, Sergey; Waterman, Clare; Liu, Jian

    Cells sense the mechanical stiffness of their extracellular matrix (ECM) by exerting traction force through focal adhesions (FAs), which are integrin-based protein assemblies. Strikingly, FA-mediated traction forces oscillate in time and space and govern durotaxis - the tendency of most cell types to migrate toward stiffer ECM. The underlying mechanism of this intriguing oscillation of FA traction force is unknown. Combing theory and experiment, we develop a model of FA growth, which integrates coordinated contributions of a branched actin network and stress fibers in the process. We show that retrograde flux of branched actin network contributes to a traction peak near the FA distal tip and that stress fiber-mediated actomyosin Contractility generates a second traction peak near the FA center. Formin-mediated stress fiber elongation negatively feeds back with actomyosin Contractility, resulting in the central traction peak oscillation. This underpins observed spatio-temporal patterns of the FA traction, and broadens the ECM stiffness range, over which FAs could accurately adapt with traction force generation. Our findings shed light on the fundamental mechanism of FA mechanosensing and hence durotaxis.

  1. Railgun power supply system utilizing traction motors and vacuum interrupters

    SciTech Connect

    Parsons, W.M.; Parker, J.V.; Thullen, P.

    1985-01-01

    A railgun power supply has been designed that utilizes traction motors, vacuum interrupters and pulse transformers. An assembly of 28 traction motors, which store approximately 75 MJ, energize the primary windings of three pulse transformers at a peak current of 50 kA. At peak current an array of vacuum interrupters disconnects the transformer primary windings and forces the current to flow in the secondary windings. The secondary windings are connected directly to the railgun and require no opening switches. By staging the vacuum interrupter openings, a 1 MA to 1.3 MA ramped current waveform can be delivered to the railgun.

  2. Teleportation of a 3-dimensional GHZ State

    NASA Astrophysics Data System (ADS)

    Cao, Hai-Jing; Wang, Huai-Sheng; Li, Peng-Fei; Song, He-Shan

    2012-05-01

    The process of teleportation of a completely unknown 3-dimensional GHZ state is considered. Three maximally entangled 3-dimensional Bell states function as quantum channel in the scheme. This teleportation scheme can be directly generalized to teleport an unknown d-dimensional GHZ state.

  3. Traction contact performance evaluation at high speeds

    NASA Technical Reports Server (NTRS)

    Tevaarwerk, J. L.

    1981-01-01

    The results of traction tests performed on two fluids are presented. These tests covered a pressure range of 1.0 to 2.5 GPa, an inlet temperature range of 30 'C to 70 'C, a speed range of 10 to 80 m/sec, aspect ratios of .5 to 5 and spin from 0 to 2.1 percent. The test results are presented in the form of two dimensionless parameters, the initial traction slope and the maximum traction peak. With the use of a suitable rheological fluid model the actual traction curves measured can now be reconstituted from the two fluid parameters. More importantly, the knowledge of these parameters together with the fluid rheological model, allow the prediction of traction under conditions of spin, slip and any combination thereof. Comparison between theoretically predicted traction under these conditions and those measured in actual traction tests shows that this method gives good results.

  4. Application of traction drives as servo mechanisms

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Rohn, D. A.; Steinetz, B. M.

    1985-01-01

    The suitability of traction drives for a wide class of aerospace control mechanisms is examined. Potential applications include antenna or solar array drive positioners, robotic joints, control moment gyro (CMG) actuators and propeller pitch change mechanisms. In these and similar applications the zero backlash, high torsional stiffness, low hysteresis and torque ripple characteristics of traction drives are of particular interest, as is the ability to run without liquid lubrication in certain cases. Wear and fatigue considerations for wet and dry operation are examined along with the tribological performance of several promising self lubricating polymers for traction contracts. The speed regulation capabilities of variable ratio traction drives are reviewed. A torsional stiffness analysis described suggests that traction contacts are relatively stiff compared to gears and are significantly stiffer than the other structural elements in the prototype CMG traction drive analyzed. Discussion is also given of an advanced turboprop propeller pitch change mechanism that incorporates a traction drive.

  5. Single Cell Traction Microscopy within 3D Collagen Matrices

    NASA Astrophysics Data System (ADS)

    Wu, Mingming

    2014-03-01

    Mechanical interaction between the cell and its extracellular matrix (ECM) regulates cellular behaviors, including proliferation, differentiation, adhesion and migration. Cells require the three dimensional (3D) architectural support of the ECM to perform physiologically realistic functions. However, our current understanding of cell-ECM and cell-cell mechanical interactions is largely derived from 2D traction force microscopy, in which cells are cultured on a flat substrate. It is now clear that what we learn about cellular behavior on a 2D substrate does not always apply to cells embedded within a 3D biomatrix. 3D traction microscopy is emerging for mapping traction fields of single cells embedded in 3D gel, but current methods cannot account for the fibrous and nonlinear properties of collagen gel. In this talk, I will present a forward computation algorithm that we have developed for 3D cell traction measurements within collagen gels. The application of this technology to understanding cancer migration and invasion will be discussed. This work is supported by the National Center for Research Resources (5R21RR025801-03, NIH) and the National Institute of General Medical Sciences (8 R21 GM103388-03,NIH), and the Cornell Center on the Microenvironment & Metastasis.

  6. 3-Dimensional Topographic Models for the Classroom

    NASA Technical Reports Server (NTRS)

    Keller, J. W.; Roark, J. H.; Sakimoto, S. E. H.; Stockman, S.; Frey, H. V.

    2003-01-01

    We have recently undertaken a program to develop educational tools using 3-dimensional solid models of digital elevation data acquired by the Mars Orbital Laser Altimeter (MOLA) for Mars as well as a variety of sources for elevation data of the Earth. This work is made possible by the use of rapid prototyping technology to construct solid 3-Dimensional models of science data. We recently acquired rapid prototyping machine that builds 3-dimensional models in extruded plastic. While the machine was acquired to assist in the design and development of scientific instruments and hardware, it is also fully capable of producing models of spacecraft remote sensing data. We have demonstrated this by using Mars Orbiter Laser Altimeter (MOLA) topographic data and Earth based topographic data to produce extruded plastic topographic models which are visually appealing and instantly engage those who handle them.

  7. Spin analysis of concentrated traction contacts

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.

    1983-01-01

    Spin, the result of a mismatch in contact radii on either side of the point of rolling, has a detrimental effect on traction contact performance. It occurs in concentrated contacts having conical or contoured rolling elements, such as those in traction drives or angular contact bearings, and is responsible for an increase in contact heating and power loss. The kinematics of spin producing contact geometries and the subsequent effect on traction and power loss are investigated. The influence of lubricant traction characteristics and contact geometries that minimize spin are also addressed.

  8. Periodic traction in migrating large amoeba of Physarum polycephalum

    PubMed Central

    Rieu, Jean-Paul; Delanoë-Ayari, Hélène; Takagi, Seiji; Tanaka, Yoshimi; Nakagaki, Toshiyuki

    2015-01-01

    The slime mould Physarum polycephalum is a giant multinucleated cell exhibiting well-known Ca2+-dependent actomyosin contractions of its vein network driving the so-called cytoplasmic shuttle streaming. Its actomyosin network forms both a filamentous cortical layer and large fibrils. In order to understand the role of each structure in the locomotory activity, we performed birefringence observations and traction force microscopy on excised fragments of Physarum. After several hours, these microplasmodia adopt three main morphologies: flat motile amoeba, chain types with round contractile heads connected by tubes and motile hybrid types. Each type exhibits oscillations with a period of about 1.5 min of cell area, traction forces and fibril activity (retardance) when fibrils are present. The amoeboid types show only peripheral forces while the chain types present a never-reported force pattern with contractile rings far from the cell boundary under the spherical heads. Forces are mostly transmitted where the actomyosin cortical layer anchors to the substratum, but fibrils maintain highly invaginated structures and contribute to forces by increasing the length of the anchorage line. Microplasmodia are motile only when there is an asymmetry in the shape and/or the force distribution. PMID:25808339

  9. 3-dimensional imaging at nanometer resolutions

    DOEpatents

    Werner, James H.; Goodwin, Peter M.; Shreve, Andrew P.

    2010-03-09

    An apparatus and method for enabling precise, 3-dimensional, photoactivation localization microscopy (PALM) using selective, two-photon activation of fluorophores in a single z-slice of a sample in cooperation with time-gated imaging for reducing the background radiation from other image planes to levels suitable for single-molecule detection and spatial location, are described.

  10. Traction Stresses and Translational Distortion of the Nucleus During Fibroblast Migration on a Physiologically Relevant ECM Mimic

    PubMed Central

    Pan, Zhi; Ghosh, Kaustabh; Liu, Yajie; Clark, Richard A.F.; Rafailovich, Miriam H.

    2009-01-01

    Cellular traction forces, resulting in cell-substrate physical interactions, are generated by actin-myosin complexes and transmitted to the extracellular matrix through focal adhesions. These processes are highly dynamic under physiological conditions and modulate cell migration. To better understand the precise dynamics of cell migration, we measured the spatiotemporal redistribution of cellular traction stresses (force per area) during fibroblast migration at a submicron level and correlated it with nuclear translocation, an indicator of cell migration, on a physiologically relevant extracellular matrix mimic. We found that nuclear translocation occurred in pulses whose magnitude was larger on the low ligand density surfaces than on the high ligand density surfaces. Large nuclear translocations only occurred on low ligand density surfaces when the rear traction stresses completely relocated to a posterior nuclear location, whereas such relocation took much longer time on high ligand density surfaces, probably due to the greater magnitude of traction stresses. Nuclear distortion was also observed as the traction stresses redistributed. Our results suggest that the reinforcement of the traction stresses around the nucleus as well as the relaxation of nuclear deformation are critical steps during fibroblast migration, serving as a speed regulator, which must be considered in any dynamic molecular reconstruction model of tissue cell migration. A traction gradient foreshortening model was proposed to explain how the relocation of rear traction stresses leads to pulsed fibroblast migration. PMID:19450499

  11. 21 CFR 890.5925 - Traction accessory.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Traction accessory. 890.5925 Section 890.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5925 Traction accessory....

  12. 21 CFR 890.5925 - Traction accessory.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Traction accessory. 890.5925 Section 890.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5925 Traction accessory....

  13. 21 CFR 890.5925 - Traction accessory.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Traction accessory. 890.5925 Section 890.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5925 Traction accessory....

  14. 21 CFR 890.5925 - Traction accessory.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Traction accessory. 890.5925 Section 890.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5925 Traction accessory....

  15. 21 CFR 890.5925 - Traction accessory.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Traction accessory. 890.5925 Section 890.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5925 Traction accessory....

  16. Elastohydrodynamic Traction Properties of Seed Oils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The elastohydrodynamic traction coefficient (tc) properties of nine seed oils of varying chemical structures, PAO and hexadecane, were investigated using a ball-on disk traction apparatus. The seed oils were: castor oil, a triglyceride with hydroxyl functional group; jojoba, a monoglyceride; and s...

  17. Elastohydrodynamic (EHD) traction properties of seed oils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The elastohydrodynamic traction coefficient (tc) properties of nine seed oils of varying chemical structures, PAO and hexadecane, were investigated using a ball-on disk traction apparatus. The seed oils were: castor oil, a triglyceride with hydroxyl functional group; jojoba, a monoglyceride; and sev...

  18. Advanced dc-Traction-Motor Control System

    NASA Technical Reports Server (NTRS)

    Vittone, O.

    1985-01-01

    Motor-control concept for battery-powered vehicles includes stateof-the-art power-transistor switching and separate excitation of motor windings in traction and regenerative braking. Switching transistors and other components of power-conditioning subsystem operate under control of computer that coordinates traction, braking, and protective functions.

  19. Biochemical Applications Of 3-Dimensional Fluorescence Spectrometry

    NASA Astrophysics Data System (ADS)

    Leiner, Marc J.; Wolfbeis, Otto S.

    1988-06-01

    We investigated the 3-dimensional fluorescence of complex mixtures of bioloquids such as human serum, serum ultrafiltrate, human urine, and human plasma low density lipoproteins. The total fluorescence of human serum can be divided into a few peaks. When comparing fluorescence topograms of sera, from normal and cancerous subjects, we found significant differences in tryptophan fluorescence. Although the total fluorescence of human urine can be resolved into 3-5 distinct peaks, some of them. do not result from single fluorescent urinary metabolites, but rather from. several species having similar spectral properties. Human plasma, low density lipoproteins possess a native fluorescence that changes when submitted to in-vitro autoxidation. The 3-dimensional fluorescence demonstrated the presence of 7 fluorophores in the lipid domain, and 6 fluorophores in the protein. dovain- The above results demonstrated that 3-dimensional fluorescence can resolve the spectral properties of complex ,lxtures much better than other methods. Moreover, other parameters than excitation and emission wavelength and intensity (for instance fluorescence lifetime, polarization, or quenchability) may be exploited to give a multidl,ensio,a1 matrix, that is unique for each sample. Consequently, 3-dimensio:Hhal fluorescence as such, or in combination with separation techniques is therefore considered to have the potential of becoming a useful new H.ethod in clinical chemistry and analytical biochemistry.

  20. Computed tomography arthrography with traction in the human hip for three-dimensional reconstruction of cartilage and the acetabular labrum

    PubMed Central

    Henak, C.R.; Abraham, C.L.; Peters, C.L.; Sanders, R.K.; Weiss, J.A.; Anderson, A.E.

    2014-01-01

    AIM To develop and demonstrate the efficacy of a computed tomography arthrography (CTA) protocol for the hip that enables accurate three-dimensional reconstructions of cartilage and excellent visualization of the acetabular labrum. MATERIALS AND METHODS Ninety-three subjects were imaged (104 scans); 68 subjects with abnormal anatomy, 11 patients after periacetabular osteotomy surgery, and 25 subjects with normal anatomy. Fifteen to 25 ml of contrast agent diluted with lidocaine was injected using a lateral oblique approach. A Hare traction splint applied traction during CT. The association between traction force and intra-articular joint space was assessed qualitatively under fluoroscopy. Cartilage geometry was reconstructed from the CTA images for 30 subjects; the maximum joint space under traction was measured. RESULTS Using the Hare traction splint, the intra-articular space and boundaries of cartilage could be clearly delineated throughout the joint; the acetabular labrum was also visible. Dysplastic hips required less traction (~5 kg) than normal and retroverted hips required (>10 kg) to separate the cartilage. An increase in traction force produced a corresponding widening of the intra-articular joint space. Under traction, the maximum width of the intra-articular joint space during CT ranged from 0.98–6.7 mm (2.46 ± 1.16 mm). CONCLUSIONS When applied to subjects with normal and abnormal hip anatomy, the CTA protocol presented yields clear delineation of the cartilage and the acetabular labrum. Use of a Hare traction splint provides a simple, cost-effective method to widen the intra-articular joint space during CT, and provides flexibility to vary the traction as required. PMID:25070373

  1. Traction reveals mechanisms of wall-effects for microswimmers near boundaries

    NASA Astrophysics Data System (ADS)

    Shen, Xinhui; Marcos, -; Fu, Henry C.

    2015-11-01

    Swimming of microorganism near solid boundaries plays an important role in various biological processes, such as biofilm formation and the early stage of infection. The influence of a plane boundary on low-Reynolds number swimmers has frequently been studied using image systems for flow singularities. However, the effect of a boundary can also be expressed in terms of the flow caused by the force or traction exerted by the boundary on the fluid. Here we show that examining the traction pattern on the boundary caused by a nearby swimmer can yield physical insight into the effect of the boundary on swimming velocities. To illustrate this point, we investigate a three-sphere swimmer initially placed parallel to a solid planar wall. The three spheres are modelled as three stokeslets and the method of images for a stokeslet is employed to solve for the traction on the wall. When the swimmer is close to the boundary, the middle sphere and end spheres produce a quadrupolar and dipolar time-averaged traction, respectively, reflecting the internal structure of the swimmer. Far away from the boundary, the time-averaged traction of the swimmer is similar to that of a pure far-field quadrupole. Thus the traction patterns reveal how close the swimmer must be to the boundary for the internal structure of the swimmer to influence the boundary effects.

  2. Hydroelectric structures studies using 3-dimensional methods

    SciTech Connect

    Harrell, T.R.; Jones, G.V.; Toner, C.K. )

    1989-01-01

    Deterioration and degradation of aged, hydroelectric project structures can significantly affect the operation and safety of a project. In many cases, hydroelectric headworks (in particular) have complicated geometrical configurations, loading patterns and hence, stress conditions. An accurate study of such structures can be performed using 3-dimensional computer models. 3-D computer models can be used for both stability evaluation and for finite element stress analysis. Computer aided engineering processes facilitate the use of 3-D methods in both pre-processing and post-processing of data. Two actual project examples are used to emphasize the authors' points.

  3. Force.

    ERIC Educational Resources Information Center

    Gamble, Reed

    1989-01-01

    Discusses pupil misconceptions concerning forces. Summarizes some of Assessment of Performance Unit's findings on meaning of (1) force, (2) force and motion in one dimension and two dimensions, and (3) Newton's second law. (YP)

  4. An analysis of traction drive torsional stiffness

    NASA Technical Reports Server (NTRS)

    Rohn, D. A.; Loewenthal, S. H.

    1983-01-01

    The tangential compliance of elastic bodies in concentrated contact applied to traction drive elements to determine their torsional stiffness was analyzed. Static loading and rotating conditions are considered. The effects of several design variables are shown. The theoretical torsional stiffness of a fixed ratio multiroller drive is computed and compared to experimental values. It is shown that the torsional compliance of the traction contacts themselves is a relatively small portion of the overall drive system compliance.

  5. Home cervical traction: evaluation of alternate equipment.

    PubMed

    Waylonis, G W; Tootle, D; Denhart, C; Pope Grattan, M M; Wapenski, J A

    1982-08-01

    Overhead intermittent cervical traction is often utilized to control the symptoms of cervical radiculopathy associated with osteoarthritis. The long-term home use of presently available counterweight systems has often presented problems including: (1) lack of patient compliance, (2) difficulty with application by elderly or debilitated patients, (3) tensing of both the cervical paraspinalis and upper extremity muscles while maneuvering the counterweights, and (4) discomfort while using the device. A prototype home pneumatic traction device was developed, which has many of the advantages of the expensive hydraulic units in common use in physical therapy departments. The initial favorable responses of 17 patients led to the development of a prototype commercial unit in cooperation with the Jobst Company. Of 36 patients who used the pneumatic traction device at home, 29 (81%) preferred it to the conventional counterweight system. Typical reasons were that it was easier to use, more "workable" and provided a steadier pull with more gradual onset of traction. Disadvantages most commonly mentioned were minor air pressure loss in the hand pump model and the complexity of the unit. The most rational approach to the use of these new pneumatic devices would be to initiate a home traction program using conventional counterweight units and then to switch to the pneumatic unit for long-term patients or those who are unable to apply conventional traction systems unassisted. PMID:7115034

  6. 3-dimensional bioprinting for tissue engineering applications.

    PubMed

    Gu, Bon Kang; Choi, Dong Jin; Park, Sang Jun; Kim, Min Sup; Kang, Chang Mo; Kim, Chun-Ho

    2016-01-01

    The 3-dimensional (3D) printing technologies, referred to as additive manufacturing (AM) or rapid prototyping (RP), have acquired reputation over the past few years for art, architectural modeling, lightweight machines, and tissue engineering applications. Among these applications, tissue engineering field using 3D printing has attracted the attention from many researchers. 3D bioprinting has an advantage in the manufacture of a scaffold for tissue engineering applications, because of rapid-fabrication, high-precision, and customized-production, etc. In this review, we will introduce the principles and the current state of the 3D bioprinting methods. Focusing on some of studies that are being current application for biomedical and tissue engineering fields using printed 3D scaffolds. PMID:27114828

  7. Changes in joint space width during Kaltenborn traction according to traction grade in healthy adults.

    PubMed

    Moon, Gui-do; Kim, Tae-Ho; Lim, Jin-Yong

    2016-01-01

    [Purpose] The aim of this study was to analyze the joint space width of the humeral head and glenoid fossa during traction under 2 grade conditions (grade 2/grade 3). [Subjects and Methods] The subjects were 20 healthy male adults who had not experienced any shoulder injury. Three radiographs were obtained with the subjects in the supine position (resting, grades 2 and 3). The glenohumeral joint space was examined on radiography. Joint space width was measured by a radiologist at the points described by Petersson and Redlund-Johnell. A radiologist blinded to the variable "resting" or "traction" performed all radiographic measurements. The joint space widths were compared by using one-way repeated-measures analysis of variance. [Results] The results of this study indicated significant differences in the changes in joint space width according to traction grade. Compared to resting, grades 2 and 3 traction significantly increased joint space width. However, no significant difference in joint space width was found between grades 2 and 3 traction. [Conclusion] Although no significant differences were found between grades 2 and 3 traction during glenohumeral joint traction, the increase in joint space width between the glenoid fossa and humeral head was highest during grade 3 traction. PMID:26957767

  8. Rolling, slip and traction measurements on low modulus materials

    NASA Technical Reports Server (NTRS)

    Tevaarwerk, J. L.

    1985-01-01

    Traction and wear tests were performed on six low modulus materials (LMM). Three different traction tests were performed to determine the suitability of the material for use as traction rollers. These were the rolling, slip and endurance traction tests. For each material the combination LMM on LMM and LMM on steel were evaluated. Rolling traction test were conducted to determine the load - velocity limits, the rolling traction coefficient of the materials and to establish the type of failures that would result when loading beyond the limit. It was found that in general a simple constant rolling traction coefficient was enough to describe the results of all the test. The slip traction tests revealed that the peak traction coefficients were considerably higher than for lubricated traction contacts. The endurance traction tests were performed to establish the durability of the LMM under conditions of prolonged traction. Wear measurements were performed during and after the test. Energetic wear rates were determined from the wear measurements conducted in the endurance traction tests. These values show that the roller wear is not severe when reasonable levels of traction are transmitted.

  9. Coordination of Flow and Traction in Migration of Amoeboid Physarum polycephalum: Model and Measurement

    NASA Astrophysics Data System (ADS)

    Lewis, Owen; Guy, Robert; Zhang, Shun; Del Alamo, Juan Carlos

    2014-11-01

    In this research, we develop a computational model of crawling Physarum based on the Immersed Boundary Method. Our model incorporates the effects of cell cytoplasm, the internal cytoskeleton and adhesions to the substrate. Cytoplasmic flows and traction stresses predicted by the model are compared to experimentally measured values obtained using simultaneous Traction Force Microscopy (TFM) and Particle Image Velocimetry (PIV). Of particular interest are stresses generated by flow and how transmission of stresses to the substrate is coordinated. We identify methods of adhesion-flow coordination which are consistent with experiments. Certain consisten coordinations are seen to be ``optimal'' with regards to crawling speed, and robust to perturbations in the extracellular environment.

  10. Advanced endoscopic submucosal dissection with traction.

    PubMed

    Imaeda, Hiroyuki; Hosoe, Naoki; Kashiwagi, Kazuhiro; Ohmori, Tai; Yahagi, Naohisa; Kanai, Takanori; Ogata, Haruhiko

    2014-07-16

    Endoscopic submucosal dissection (ESD) has been established as a standard treatment for early stage gastric cancer (EGC) in Japan and has spread worldwide. ESD has been used not only for EGC but also for early esophageal and colonic cancers. However, ESD is associated with several adverse events, such as bleeding and perforation, which requires more skill. Adequate tissue tension and clear visibility of the tissue to be dissected are important for effective and safe dissection. Many ESD methods using traction have been developed, such as clip-with-line method, percutaneous traction method, sinker-assisted method, magnetic anchor method, external forceps method, internal-traction method, double-channel-scope method, outerroute method, double-scope method, endoscopic-surgical-platform, and robot-assisted method. Each method has both advantages and disadvantages. Robotic endoscopy, enabling ESD with a traction method, will become more common due to advances in technology. In the near future, simple, noninvasive, and effective ESD using traction is expected to be developed and become established as a worldwide standard treatment for superficial gastrointestinal neoplasias. PMID:25031787

  11. Simulation of curving behaviour under high traction in lubricated wheel-rail contacts

    NASA Astrophysics Data System (ADS)

    Arias-Cuevas, Oscar; Li, Zili; Popovici, Radu I.; Schipper, Dik J.

    2010-12-01

    Migration of the flange lubricant to the top of the high rail may compromise the traction of a rail vehicle and affect its curving behaviour. In order to simulate this possible situation, a lubrication model has been coupled to commercial multi-body dynamics software to describe the tangential formulation of the lubricated high-rail contact. Different friction levels have been adopted for the low rail to study their influence on the curving behaviour and traction. Since the creep force in the wheel-rail contact approaches saturation of the friction, the traction control unit of the rail vehicle under study has also been modelled to account for the reduction of the wheel axle torque in the presence of wheel macro-slip.

  12. Modulating DNA configuration by interfacial traction: an elastic rod model to characterize DNA folding and unfolding.

    PubMed

    Huang, Zaixing

    2011-01-01

    As a continuum model of DNA, a thin elastic rod subjected to interfacial interactions is used to investigate the equilibrium configuration of DNA in intracellular solution. The interfacial traction between the rod and the solution environment is derived in detail. Kirchhoff's theory of elastic rods is used to analyze the equilibrium configuration of a DNA segment under the action of the interfacial traction. The influences of the interfacial energy factor and bending stiffness on the toroidal spool formation of the DNA segment are discussed. The results show that the equilibrium configuration of DNA is mainly determined by competition between the interfacial energy and elastic strain energy of the DNA itself, and the interfacial traction is one of the forces that drives DNA folding and unfolding. PMID:22210963

  13. Effects of intermittent traction therapy in an experimental spinal column model.

    PubMed

    Shin, Jeong-Hun; Jun, Seung-lyul; Lee, Young-Jun; Kim, Jae-Hyo; Hwang, Sung-Yeoun; Ahn, Seong-Hun

    2014-04-01

    Traction therapy, which is known to be a treatment method for scoliosis, one of many muscles disease, has been used since Hippocrates introduced it. However, the effects of traction therapy are still not clear. In addition, the meridian sinew theory, which is related to muscle treatment and is mentioned in the book on meridian sinews in the Miraculous Pivot of Huangdi's Internal Classic, has not been the subject of much study. For these reasons, experimental spinal models were made for this study to observe and analyze the lengths of vertebral interspaces after intermittent traction therapy, which is known to be excellent among muscle treatment methods, with various tensile forces. The results showed that the effects of intermittent traction therapy were unclear and that it might be harmful, especially when the pain was induced by muscle weakness. Because the results of this study on intermittent traction therapy were different from those expected from osteopathy or craniosacral theory, better studies of the subject are necessary. PMID:24745867

  14. Recent traction methods for endoscopic submucosal dissection

    PubMed Central

    Tsuji, Kunihiro; Yoshida, Naohiro; Nakanishi, Hiroyoshi; Takemura, Kenichi; Yamada, Shinya; Doyama, Hisashi

    2016-01-01

    Endoscopic mucosal resection (EMR) is problematic with regard to en bloc and curable resection rates. Advancements in endoscopic techniques have enabled novel endoscopic approaches such as endoscopic submucosal dissection (ESD), which has overcome some EMR problems, and has become the standard treatment for gastrointestinal tumors. However, ESD is technically difficult. Procedure time is longer and complications such as intraoperative perforation and bleeding occur more frequently than in EMR. Recently various traction methods have been introduced to facilitate ESD procedures, such as clip with line, external forceps, clip and snare, internal traction, double scope, and magnetic anchor. Each method must be used appropriately according to the anatomical characteristics. In this review we discuss recently proposed traction methods for ESD based on the characteristics of various anatomical sites. PMID:27468186

  15. Changes in joint space width during Kaltenborn traction according to traction grade in healthy adults

    PubMed Central

    Moon, Gui-do; Kim, Tae-ho; Lim, Jin-yong

    2016-01-01

    [Purpose] The aim of this study was to analyze the joint space width of the humeral head and glenoid fossa during traction under 2 grade conditions (grade 2/grade 3). [Subjects and Methods] The subjects were 20 healthy male adults who had not experienced any shoulder injury. Three radiographs were obtained with the subjects in the supine position (resting, grades 2 and 3). The glenohumeral joint space was examined on radiography. Joint space width was measured by a radiologist at the points described by Petersson and Redlund-Johnell. A radiologist blinded to the variable “resting” or “traction” performed all radiographic measurements. The joint space widths were compared by using one-way repeated-measures analysis of variance. [Results] The results of this study indicated significant differences in the changes in joint space width according to traction grade. Compared to resting, grades 2 and 3 traction significantly increased joint space width. However, no significant difference in joint space width was found between grades 2 and 3 traction. [Conclusion] Although no significant differences were found between grades 2 and 3 traction during glenohumeral joint traction, the increase in joint space width between the glenoid fossa and humeral head was highest during grade 3 traction. PMID:26957767

  16. Traction boundary conditions for molecular static simulations

    NASA Astrophysics Data System (ADS)

    Li, Xiantao; Lu, Jianfeng

    2016-08-01

    This paper presents a consistent approach to prescribe traction boundary conditions in atomistic models. Due to the typical multiple-neighbor interactions, finding an appropriate boundary condition that models a desired traction is a non-trivial task. We first present a one-dimensional example, which demonstrates how such boundary conditions can be formulated. We further analyze the stability, and derive its continuum limit. We also show how the boundary conditions can be extended to higher dimensions with an application to a dislocation dipole problem under shear stress.

  17. TRAM HOUSE INTERIOR, LOOKING SOUTHEAST. NOTE TRACTION CABLE BULL WHEEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    TRAM HOUSE INTERIOR, LOOKING SOUTHEAST. NOTE TRACTION CABLE BULL WHEEL AND DEPARTING BUCKET "12," STILL ON RAIL AND JUST PRIOR TO ENGAGING TRACTION CABLE. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  18. Cardiothoracic Applications of 3-dimensional Printing.

    PubMed

    Giannopoulos, Andreas A; Steigner, Michael L; George, Elizabeth; Barile, Maria; Hunsaker, Andetta R; Rybicki, Frank J; Mitsouras, Dimitris

    2016-09-01

    Medical 3-dimensional (3D) printing is emerging as a clinically relevant imaging tool in directing preoperative and intraoperative planning in many surgical specialties and will therefore likely lead to interdisciplinary collaboration between engineers, radiologists, and surgeons. Data from standard imaging modalities such as computed tomography, magnetic resonance imaging, echocardiography, and rotational angiography can be used to fabricate life-sized models of human anatomy and pathology, as well as patient-specific implants and surgical guides. Cardiovascular 3D-printed models can improve diagnosis and allow for advanced preoperative planning. The majority of applications reported involve congenital heart diseases and valvular and great vessels pathologies. Printed models are suitable for planning both surgical and minimally invasive procedures. Added value has been reported toward improving outcomes, minimizing perioperative risk, and developing new procedures such as transcatheter mitral valve replacements. Similarly, thoracic surgeons are using 3D printing to assess invasion of vital structures by tumors and to assist in diagnosis and treatment of upper and lower airway diseases. Anatomic models enable surgeons to assimilate information more quickly than image review, choose the optimal surgical approach, and achieve surgery in a shorter time. Patient-specific 3D-printed implants are beginning to appear and may have significant impact on cosmetic and life-saving procedures in the future. In summary, cardiothoracic 3D printing is rapidly evolving and may be a potential game-changer for surgeons. The imager who is equipped with the tools to apply this new imaging science to cardiothoracic care is thus ideally positioned to innovate in this new emerging imaging modality. PMID:27149367

  19. Thrombin-induced contraction in alveolar epithelial cells probed by traction microscopy.

    PubMed

    Gavara, Núria; Sunyer, Raimon; Roca-Cusachs, Pere; Farré, Ramon; Rotger, Mar; Navajas, Daniel

    2006-08-01

    Contractile tension of alveolar epithelial cells plays a major role in the force balance that regulates the structural integrity of the alveolar barrier. The aim of this work was to study thrombin-induced contractile forces of alveolar epithelial cells. A549 alveolar epithelial cells were challenged with thrombin, and time course of contractile forces was measured by traction microscopy. The cells exhibited basal contraction with total force magnitude 55.0 +/- 12.0 nN (mean +/- SE, n = 12). Traction forces were exerted predominantly at the cell periphery and pointed to the cell center. Thrombin (1 U/ml) induced a fast and sustained 2.5-fold increase in traction forces, which maintained peripheral and centripetal distribution. Actin fluorescent staining revealed F-actin polymerization and enhancement of peripheral actin rim. Disruption of actin cytoskeleton with cytochalasin D (5 microM, 30 min) and inhibition of myosin light chain kinase with ML-7 (10 microM, 30 min) and Rho kinase with Y-27632 (10 microM, 30 min) markedly depressed basal contractile tone and abolished thrombin-induced cell contraction. Therefore, the contractile response of alveolar epithelial cells to the inflammatory agonist thrombin was mediated by actin cytoskeleton remodeling and actomyosin activation through myosin light chain kinase and Rho kinase signaling pathways. Thrombin-induced contractile tension might further impair alveolar epithelial barrier integrity in the injured lung. PMID:16675616

  20. Three single wheel machines for traction and soil compaction research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three single wheel machines for traction and soil compaction research have been developed in recent years at the USDA-ARS National Soil Dynamics Laboratory. The Traction Research Vehicle has been used extensively for soil bin traction and soil compaction experiments. The vehicle uses feedback comp...

  1. 21 CFR 882.5960 - Skull tongs for traction.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Skull tongs for traction. 882.5960 Section 882...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5960 Skull tongs for traction. (a) Identification. Skull tongs for traction is an instrument used to immobilize a patient with...

  2. 21 CFR 882.5960 - Skull tongs for traction.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Skull tongs for traction. 882.5960 Section 882...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5960 Skull tongs for traction. (a) Identification. Skull tongs for traction is an instrument used to immobilize a patient with...

  3. 21 CFR 882.5960 - Skull tongs for traction.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Skull tongs for traction. 882.5960 Section 882...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5960 Skull tongs for traction. (a) Identification. Skull tongs for traction is an instrument used to immobilize a patient with...

  4. 21 CFR 882.5960 - Skull tongs for traction.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Skull tongs for traction. 882.5960 Section 882...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5960 Skull tongs for traction. (a) Identification. Skull tongs for traction is an instrument used to immobilize a patient with...

  5. 21 CFR 882.5960 - Skull tongs for traction.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Skull tongs for traction. 882.5960 Section 882...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5960 Skull tongs for traction. (a) Identification. Skull tongs for traction is an instrument used to immobilize a patient with...

  6. Incorporating 3-dimensional models in online articles

    PubMed Central

    Cevidanes, Lucia H. S.; Ruellasa, Antonio C. O.; Jomier, Julien; Nguyen, Tung; Pieper, Steve; Budin, Francois; Styner, Martin; Paniagua, Beatriz

    2015-01-01

    Introduction The aims of this article were to introduce the capability to view and interact with 3-dimensional (3D) surface models in online publications, and to describe how to prepare surface models for such online 3D visualizations. Methods Three-dimensional image analysis methods include image acquisition, construction of surface models, registration in a common coordinate system, visualization of overlays, and quantification of changes. Cone-beam computed tomography scans were acquired as volumetric images that can be visualized as 3D projected images or used to construct polygonal meshes or surfaces of specific anatomic structures of interest. The anatomic structures of interest in the scans can be labeled with color (3D volumetric label maps), and then the scans are registered in a common coordinate system using a target region as the reference. The registered 3D volumetric label maps can be saved in .obj, .ply, .stl, or .vtk file formats and used for overlays, quantification of differences in each of the 3 planes of space, or color-coded graphic displays of 3D surface distances. Results All registered 3D surface models in this study were saved in .vtk file format and loaded in the Elsevier 3D viewer. In this study, we describe possible ways to visualize the surface models constructed from cone-beam computed tomography images using 2D and 3D figures. The 3D surface models are available in the article’s online version for viewing and downloading using the reader’s software of choice. These 3D graphic displays are represented in the print version as 2D snapshots. Overlays and color-coded distance maps can be displayed using the reader’s software of choice, allowing graphic assessment of the location and direction of changes or morphologic differences relative to the structure of reference. The interpretation of 3D overlays and quantitative color-coded maps requires basic knowledge of 3D image analysis. Conclusions When submitting manuscripts, authors can

  7. Elastic response of DNA molecules under the action of interfacial traction and stretching: An elastic thin rod model

    NASA Astrophysics Data System (ADS)

    Xiao, Ye; Huang, Zaixing; Qiang, Lei; Gao, Jun

    2015-11-01

    In a multivalent salt solution, a segment of DNA is modeled as an elastic rod subjected to the interfacial traction. The shooting method is used to calculate the equilibrium configurations of condensed DNA under the action of the longitudinal end-force and interfacial traction simultaneously. The results show that the shapes of DNA are mainly determined by the competition between the interfacial energy and elastic strain energy of stretching. The change of end-to-end distance with the longitudinal end-force is consistent with the worm-like chain (WLC) model. The higher the concentration is, the stronger the condensation of DNA.

  8. Perioperative lower extremity peripheral nerve traction injuries.

    PubMed

    Plastaras, Christopher T; Chhatre, Akhil; Kotcharian, Ashot S

    2014-01-01

    Peripheral nerve traction injuries may occur after surgical care and can involve any of the lower extremity large peripheral nerves. In this review, the authors discuss injuries after knee or hip surgical intervention. The diagnosis, including electrodiagnostic studies, is time sensitive and also relies on a detailed history and physical examination. Successful prevention and treatment involve familiarity with risk and predisposing factors as well as prophylactic measures. PMID:24267207

  9. A stochastic description on the traction-separation law of an interface with non-covalent bonding

    NASA Astrophysics Data System (ADS)

    Wei, Yujie

    2014-10-01

    We formulate a stochastic description about the mechanical response of an interface composed of non-covalent bonds. In such interfaces, the evolution of bonding probability in response to deformation plays the central role in determining their traction-separation behavior. The model connects atomistic and molecular level bonding properties to meso-scale traction-separation relationship in an interface. In response to quasi-static loading, the traction-separation of a stochastic interface is the resultant of varying bonding probability as a function of separation, and the bonding probability follows the Boltzmann distribution. The quasi-static stochastic interface model is applied to understand the critical force while detaching a sphere from an infinite half space. We further show the kinetics of interfacial debonding in the context of the Bell model (1978) and two of its derivatives - the Evans-Richie model (1997) and the Freund model (2009). While subjected to constant force, an interface creeps and its separation-time curve shows typical characteristics seen during the creep of crystalline materials at high temperature. When we exert constant separation rate to an interface, interfacial traction shows strong rate-sensitivity with higher traction at faster separation rate. The model presented here may supply a guidance to bring the stochastic nature of interfacial debonding into theories on cracking initiation and growth during fatigue fracture.

  10. Electric Transport Traction Power Supply System With Distributed Energy Sources

    NASA Astrophysics Data System (ADS)

    Abramov, E. Y.; Schurov, N. I.; Rozhkova, M. V.

    2016-04-01

    The paper states the problem of traction substation (TSS) leveling of daily-load curve for urban electric transport. The circuit of traction power supply system (TPSS) with distributed autonomous energy source (AES) based on photovoltaic (PV) and energy storage (ES) units is submitted here. The distribution algorithm of power flow for the daily traction load curve leveling is also introduced in this paper. In addition, it illustrates the implemented experiment model of power supply system.

  11. Model for how retrograde actin flow regulates adhesion traction stresses.

    PubMed

    Li, Ying; Bhimalapuram, Prabhakar; Dinner, Aaron R

    2010-05-19

    Cells from animals adhere to and exert mechanical forces on their surroundings. Cells must control these forces for many biological processes, and dysfunction can lead to pathologies. How the actions of molecules within a cell are coordinated to regulate the adhesive interaction with the extracellular matrix remains poorly understood. It has been observed that cytoplasmic proteins that link integrin cell-surface receptors with the actin cytoskeleton flow with varying rates from the leading edge toward the center of a cell. Here, we explore theoretically how measurable subcellular traction stresses depend on the local speed of retrograde actin flow. In the model, forces result from the stretching of molecular complexes in response to the drag from the flow; because these complexes break with extension-dependent kinetics, the flow results in a decrease in their number when sufficiently large. Competition between these two effects naturally gives rise to a clutch-like behavior and a nonmonotonic trend in the measured stresses, consistent with recent data for epithelial cells. We use this basic framework to evaluate slip and catch bond mechanisms for integrins; better fits of experimental data are obtained with a catch bond representation. Extension of the model to one comprising multiple molecular interfaces shifts the peak stress to higher speeds. Connections to other models and cell movement are discussed. PMID:21386439

  12. Simplified fatigue life analysis for traction drive contacts

    NASA Technical Reports Server (NTRS)

    Rohn, D. A.; Loewenthal, S. H.; Coy, J. J.

    1980-01-01

    A simplified fatigue life analysis for traction drive contacts of arbitrary geometry is presented. The analysis is based on the Lundberg-Palmgren theory used for rolling-element bearings. The effects of torque, element size, speed, contact ellipse ratio, and the influence of traction coefficient are shown. The analysis shows that within the limits of the available traction coefficient, traction contacts exhibit longest life at high speeds. Multiple, load-sharing roller arrangements have an advantageous effect on system life, torque capacity, power-to-weight ratio and size.

  13. Grain Boundary Traction Signatures: Quantitative Predictors of Dislocation Emission

    NASA Astrophysics Data System (ADS)

    Li, Ruizhi; Chew, Huck Beng

    2016-08-01

    We introduce the notion of continuum-equivalent traction fields as local quantitative descriptors of the grain boundary interface. These traction-based descriptors are capable of predicting the critical stresses to trigger dislocation emissions from ductile ⟨110 ⟩ symmetrical-tilt nickel grain boundaries. We show that Shockley partials are emitted when the grain boundary tractions, in combination with external tensile loading, generate a resolved shear stress to cause dislocation slip. The relationship between the local grain boundary tractions and the grain boundary energy is established.

  14. Grain Boundary Traction Signatures: Quantitative Predictors of Dislocation Emission.

    PubMed

    Li, Ruizhi; Chew, Huck Beng

    2016-08-19

    We introduce the notion of continuum-equivalent traction fields as local quantitative descriptors of the grain boundary interface. These traction-based descriptors are capable of predicting the critical stresses to trigger dislocation emissions from ductile ⟨110⟩ symmetrical-tilt nickel grain boundaries. We show that Shockley partials are emitted when the grain boundary tractions, in combination with external tensile loading, generate a resolved shear stress to cause dislocation slip. The relationship between the local grain boundary tractions and the grain boundary energy is established. PMID:27588865

  15. Physical forces during collective cell migration

    NASA Astrophysics Data System (ADS)

    Trepat, Xavier; Wasserman, Michael R.; Angelini, Thomas E.; Millet, Emil; Weitz, David A.; Butler, James P.; Fredberg, Jeffrey J.

    2009-06-01

    Fundamental biological processes including morphogenesis, tissue repair and tumour metastasis require collective cell motions, and to drive these motions cells exert traction forces on their surroundings. Current understanding emphasizes that these traction forces arise mainly in `leader cells' at the front edge of the advancing cell sheet. Our data are contrary to that assumption and show for the first time by direct measurement that traction forces driving collective cell migration arise predominately many cell rows behind the leading front edge and extend across enormous distances. Traction fluctuations are anomalous, moreover, exhibiting broad non-Gaussian distributions characterized by exponential tails. Taken together, these unexpected findings demonstrate that although the leader cell may have a pivotal role in local cell guidance, physical forces that it generates are but a small part of a global tug-of-war involving cells well back from the leading edge.

  16. 'Traction ribs' on the palaeo-ice stream tracks of the Interior Plains, North America

    NASA Astrophysics Data System (ADS)

    Margold, Martin; Stokes, Chris R.

    2015-04-01

    Spatially distinct pattern of basal shear stress beneath a number of Antarctic and Greenlandic ice streams has recently been discovered by inverse methods using high resolution data of ice velocity, elevation and thickness. Surrounded by regions of near-zero basal shear stress, these areas of high basal shear stress have been termed 'traction ribs' and hold important implications for the force balance of ice streams. The cause of the traction ribs is unknown (i.e. whether they have a topographic expression), but their horizontal dimensions and pattern lie somewhere between typical ribbed (Rogen) moraines and recently described mega-scale ribbed moraines identified on palaeo-ice sheet beds. However, whilst both of these landform types form with their long axis transverse to the ice flow direction, the traction ribs are most commonly oriented oblique to the ice flow at angles of 30-60 degrees. Here, we report new findings from the beds of palaeo-ice streams on the Interior Plains in Alberta and Saskatchewan where landform assemblages, similar to traction ribs, occur at several sites. Individual landforms at the mapped sites have typical lengths (transverse to flow) of 5-10 km, width of ~2 km, and their spacing is ~2-3 km. As such, they appear to represent an intermediate scale of ribbed landform that overlaps with the more extreme (larger) values of classic ribbed moraine and the smaller values of mega-ribs. Unlike mega-ribs and ribbed moraines, we also note that many of the ribbed features we mapped are aligned obliquely to ice flow direction at angles and mimic the arcuate patterns of traction ribs seen under modern ice streams. Profiles across the ridges indicate that they have amplitudes of 10-15 m which is comparable, but slightly lower than the mean value for ribbed moraines. The resemblance of our newly mapped features to the traction ribs of modern ice streams is close not only in the size and shape but also in the overall pattern of the whole landform

  17. Simple cost model for EV traction motors

    NASA Astrophysics Data System (ADS)

    Cuenca, R. M.

    1995-02-01

    A simple cost model has been developed that allows the calculation of the OEM (original equipment manufacturer) cost of electric traction motors of three different types, normalized as a function of power in order to accommodate different power and size. The model includes enough information on the various elements integrated in the motors to allow analysis of individual components and to factor-in the effects of changes in commodities prices. A scalable cost model for each of the main components of an electric vehicle (EV) is a useful tool that can have direct application in computer simulation or in parametric studies. For the cost model to have wide usefulness, it needs to be valid for a range of values of some parameter that determines the magnitude or size of the component. For instance, in the case of batteries, size may be determined by energy capacity, usually expressed in kilowatt-hours (kWh), while in the case of traction motors, size is better determined by rated power, usually expressed in kilowatts (kW). The simplest case is when the cost of the component in question is a direct function of its size; then cost is simply the product of its specific cost ($/unit size) and the number of units (size) in the vehicle in question. Batteries usually fall in this category (cost = energy capacity x $/kWh). But cost is not always linear with size or magnitude; motors (and controllers), for instance, become relatively less expensive as power rating increases. Traction motors, one of the main components for EV powertrains, are examined in this paper, and a simplified cost model is developed for the three most popular design variations.

  18. Progressive Release of Vitreomacular Traction With Aflibercept.

    PubMed

    Schwartz, Stephen G; Flynn, Harry W

    2016-05-01

    A patient with combined diabetic macular edema (DME) and vitreomacular traction (VMT) was treated with a series of intravitreal aflibercept (Eylea; Regeneron, Tarrytown, NY) injections. The VMT progressively released during the course of the five intravitreal injections. This release may have been spontaneous, due to a nonspecific mechanical effect from the injections, or due to a pharmacologic effect from the aflibercept. While treating DME, anti-vascular endothelial growth factor agents may have an additional benefit in releasing VMT. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:477-481.]. PMID:27183554

  19. Visualizing the interior architecture of focal adhesions with high-resolution traction maps.

    PubMed

    Morimatsu, Masatoshi; Mekhdjian, Armen H; Chang, Alice C; Tan, Steven J; Dunn, Alexander R

    2015-04-01

    Focal adhesions (FAs) are micron-sized protein assemblies that coordinate cell adhesion, migration, and mechanotransduction. How the many proteins within FAs are organized into force sensing and transmitting structures is poorly understood. We combined fluorescent molecular tension sensors with super-resolution light microscopy to visualize traction forces within FAs with <100 nm spatial resolution. We find that αvβ3 integrin selectively localizes to high force regions. Paxillin, which is not generally considered to play a direct role in force transmission, shows a higher degree of spatial correlation with force than vinculin, talin, or α-actinin, proteins with hypothesized roles as force transducers. These observations suggest that αvβ3 integrin and paxillin may play important roles in mechanotransduction. PMID:25730141

  20. Life analysis of multiroller planetary traction drive

    NASA Technical Reports Server (NTRS)

    Coy, J. J.; Rohn, D. A.; Loewenthal, S. H.

    1981-01-01

    A contact fatigue life analysis was performed for a constant ratio, Nasvytis Multiroller Traction Drive. The analysis was based on the Lundberg-Palmgren method for rolling element bearing life prediction. Life adjustment factors for materials, processing, lubrication and traction were included. The 14.7 to 1 ratio drive consisted of a single stage planetary configuration with two rows of stepped planet rollers of five rollers per row, having a roller cluster diameter of approximately 0.21 m, a width of 0.06 m and a weight of 9 kg. Drive system 10 percent life ranged from 18,800 hours at 16.6 kW (22.2 hp) and 25,000 rpm sun roller speed, to 305 hours at maximum operating conditions of 149 kw (200 hp) and 75,000 rpm sun roller speed. The effect of roller diameter and roller center location on life were determined. It was found that an optimum life geometry exists.

  1. DETAIL OF TRACTION CABLE ENGAGEMENT DEVICE. SMALL, KNOBBED LEVER ON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL OF TRACTION CABLE ENGAGEMENT DEVICE. SMALL, KNOBBED LEVER ON BUCKET HANGER WAS PULLED DOWN BY A CAMEL (FIXED CAM RAIL AT CENTER) AS BUCKET ROLLED PAST IT, CAUSING A CLAMP TO CLOSE AGAINST TRACTION CABLE. A SIMILAR CAMEL (NO LONGER EXTANT) DISENGAGED CLAMP ON RECEIVING SIDE. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  2. Development of Traction Drive Motors for the Toyota Hybrid System

    NASA Astrophysics Data System (ADS)

    Kamiya, Munehiro

    Toyota Motor Corporation developed in 2005 a new hybrid system for a large SUV. This system included the new development of a high-speed traction drive motor achieving a significant increase in power weight ratio. This paper provides an overview of the hybrid system, discusses the characteristics required of a traction drive motor, and presents the technologies employed in the developed motor.

  3. From 2-dimensional cephalograms to 3-dimensional computed tomography scans.

    PubMed

    Halazonetis, Demetrios J

    2005-05-01

    Computed tomography is entering the orthodontic specialty as a mainstream diagnostic modality. Radiation exposure and cost have decreased significantly, and the diagnostic value is very high compared with traditional radiographic options. However, 3-dimensional data present new challenges and need a different approach from traditional viewing of static images to make the most of the available possibilities. Advances in computer hardware and software now enable interactive display of the data on personal computers, with the ability to selectively view soft or hard tissues from any angle. Transfer functions are used to apply transparency and color. Cephalometric measurements can be taken by digitizing points in 3-dimensional coordinates. Application of 3-dimensional data is expected to increase significantly soon and might eventually replace many conventional orthodontic records that are in use today. PMID:15877045

  4. Electric vehicle regenerative antiskid braking and traction control system

    DOEpatents

    Cikanek, Susan R.

    1995-01-01

    An antiskid braking and traction control system for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes one or more sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensors and determining if regenerative antiskid braking control, requiring hydrualic braking control, or requiring traction control are required. The processor then employs a control strategy based on the determined vehicle state and provides command signals to a motor controller to control the operation of the electric traction motor and to a brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative antiskid braking control, hydraulic braking control, and traction control.

  5. Electric vehicle regenerative antiskid braking and traction control system

    DOEpatents

    Cikanek, S.R.

    1995-09-12

    An antiskid braking and traction control system for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes one or more sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensors and determining if regenerative antiskid braking control, requiring hydraulic braking control, or requiring traction control are required. The processor then employs a control strategy based on the determined vehicle state and provides command signals to a motor controller to control the operation of the electric traction motor and to a brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative antiskid braking control, hydraulic braking control, and traction control. 10 figs.

  6. Differential Cross Section Kinematics for 3-dimensional Transport Codes

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Dick, Frank

    2008-01-01

    In support of the development of 3-dimensional transport codes, this paper derives the relevant relativistic particle kinematic theory. Formulas are given for invariant, spectral and angular distributions in both the lab (spacecraft) and center of momentum frames, for collisions involving 2, 3 and n - body final states.

  7. Controlled teleportation of a 3-dimensional bipartite quantum state

    NASA Astrophysics Data System (ADS)

    Cao, Hai-Jing; Chen, Zhong-Hua; Song, He-Shan

    2008-07-01

    A controlled teleportation scheme of an unknown 3-dimensional (3D) two-particle quantum state is proposed, where a 3D Bell state and 3D GHZ state function as the quantum channel. This teleportation scheme can be directly generalized to teleport an unknown d-dimensional bipartite quantum state.

  8. Advanced Electric Traction System Technology Development

    SciTech Connect

    Anderson, Iver

    2011-01-14

    As a subcontractor to General Motors (GM), Ames Laboratory provided the technical expertise and supplied experimental materials needed to assess the technology of high energy bonded permanent magnets that are injection or compression molded for use in the Advanced Electric Traction System motor. This support was a sustained (Phase 1: 6/07 to 3/08) engineering effort that builds on the research achievements of the primary FreedomCAR project at Ames Laboratory on development of high temperature magnet alloy particulate in both flake and spherical powder forms. Ames Lab also provide guidance and direction in selection of magnet materials and supported the fabrication of experimental magnet materials for development of injection molding and magnetization processes by Arnold Magnetics, another project partner. The work with Arnold Magnetics involved a close collaboration on particulate material design and processing to achieve enhanced particulate properties and magnetic performance in the resulting bonded magnets. The overall project direction was provided by GM Program Management and two design reviews were held at GM-ATC in Torrance, CA. Ames Lab utilized current expertise in magnet powder alloy design and processing, along with on-going research advances being achieved under the existing FreedomCAR Program project to help guide and direct work during Phase 1 for the Advanced Electric Traction System Technology Development Program. The technical tasks included review of previous GM and Arnold Magnets work and identification of improvements to the benchmark magnet material, Magnequench MQP-14-12. Other benchmark characteristics of the desired magnet material include 64% volumetric loading with PPS polymer and a recommended maximum use temperature of 200C. A collaborative relationship was maintained with Arnold Magnets on the specification and processing of the bonded magnet material required by GM-ATC.

  9. An advanced pitch change mechanism incorporating a hybrid traction drive

    NASA Technical Reports Server (NTRS)

    Steinetz, B. M.; Loewenthal, S. H.; Sargisson, D. F.; White, G.

    1984-01-01

    A design of a propeller pitch control mechanism is described that meets the demanding requirements of a high-power, advanced turboprop. In this application, blade twisting moment torque can be comparable to that of the main reduction gearbox output: precise pitch control, reliability and compactness are all at a premium. A key element in the design is a compact, high-ratio hybrid traction drive which offers low torque ripple and high torsional stiffness. The traction drive couples a high speed electric motor/alternator unit to a ball screw that actuates the blade control links. The technical merits of this arrangement and the performance characteristics of the traction drive are discussed.

  10. Energy and wear optimisation of train longitudinal dynamics and of traction and braking systems

    NASA Astrophysics Data System (ADS)

    Conti, R.; Galardi, E.; Meli, E.; Nocciolini, D.; Pugi, L.; Rindi, A.

    2015-05-01

    Traction and braking systems deeply affect longitudinal train dynamics, especially when an extensive blending phase among different pneumatic, electric and magnetic devices is required. The energy and wear optimisation of longitudinal vehicle dynamics has a crucial economic impact and involves several engineering problems such as wear of braking friction components, energy efficiency, thermal load on components, level of safety under degraded or adhesion conditions (often constrained by the current regulation in force on signalling or other safety-related subsystem). In fact, the application of energy storage systems can lead to an efficiency improvement of at least 10% while, as regards the wear reduction, the improvement due to distributed traction systems and to optimised traction devices can be quantified in about 50%. In this work, an innovative integrated procedure is proposed by the authors to optimise longitudinal train dynamics and traction and braking manoeuvres in terms of both energy and wear. The new approach has been applied to existing test cases and validated with experimental data provided by Breda and, for some components and their homologation process, the results of experimental activities derive from cooperation performed with relevant industrial partners such as Trenitalia and Italcertifer. In particular, simulation results are referred to the simulation tests performed on a high-speed train (Ansaldo Breda Emu V250) and on a tram (Ansaldo Breda Sirio Tram). The proposed approach is based on a modular simulation platform in which the sub-models corresponding to different subsystems can be easily customised, depending on the considered application, on the availability of technical data and on the homologation process of different components.

  11. Multimodality 3-Dimensional Image Integration for Congenital Cardiac Catheterization

    PubMed Central

    2014-01-01

    Cardiac catheterization procedures for patients with congenital and structural heart disease are becoming more complex. New imaging strategies involving integration of 3-dimensional images from rotational angiography, magnetic resonance imaging (MRI), computerized tomography (CT), and transesophageal echocardiography (TEE) are employed to facilitate these procedures. We discuss the current use of these new 3D imaging technologies and their advantages and challenges when used to guide complex diagnostic and interventional catheterization procedures in patients with congenital heart disease. PMID:25114757

  12. Mechanical Lumbar Traction: What Is Its Place in Clinical Practice?

    PubMed

    2016-03-01

    Summary evidence concludes that mechanical lumbar traction is not effective for treating acute or chronic nonspecific low back pain (LBP). However, many physical therapists continue to use it, primarily as an additional modality. Indeed, expert clinical opinion, theoretical models, and some research evidence suggest that certain patients with LBP respond positively to traction. A study published in the March 2016 issue of JOSPT investigates the effectiveness of traction in prone as an adjunct to an extension-oriented exercise program in patients with LBP and leg pain and explores whether a previously identified set of patient characteristics is associated with better outcomes from traction. In this Perspectives for Practice, the authors explain the impact of their findings for clinicians treating these patients. PMID:26928736

  13. Model for adhesion clutch explains biphasic relationship between actin flow and traction at the cell leading edge

    NASA Astrophysics Data System (ADS)

    Craig, Erin M.; Stricker, Jonathan; Gardel, Margaret; Mogilner, Alex

    2015-05-01

    Cell motility relies on the continuous reorganization of a dynamic actin-myosin-adhesion network at the leading edge of the cell, in order to generate protrusion at the leading edge and traction between the cell and its external environment. We analyze experimentally measured spatial distributions of actin flow, traction force, myosin density, and adhesion density in control and pharmacologically perturbed epithelial cells in order to develop a mechanical model of the actin-adhesion-myosin self-organization at the leading edge. A model in which the F-actin network is treated as a viscous gel, and adhesion clutch engagement is strengthened by myosin but weakened by actin flow, can explain the measured molecular distributions and correctly predict the spatial distributions of the actin flow and traction stress. We test the model by comparing its predictions with measurements of the actin flow and traction stress in cells with fast and slow actin polymerization rates. The model predicts how the location of the lamellipodium-lamellum boundary depends on the actin viscosity and adhesion strength. The model further predicts that the location of the lamellipodium-lamellum boundary is not very sensitive to the level of myosin contraction.

  14. Rare-Earth-Free Traction Motor: Rare Earth-Free Traction Motor for Electric Vehicle Applications

    SciTech Connect

    2012-01-01

    REACT Project: Baldor will develop a new type of traction motor with the potential to efficiently power future generations of EVs. Unlike today’s large, bulky EV motors which use expensive, imported rare-earth-based magnets, Baldor’s motor could be light, compact, contain no rare earth materials, and have the potential to deliver more torque at a substantially lower cost. Key innovations in this project include the use of a unique motor design, incorporation of an improved cooling system, and the development of advanced materials manufacturing techniques. These innovations could significantly reduce the cost of an electric motor.

  15. Theory of relativistic Brownian motion: the (1+3) -dimensional case.

    PubMed

    Dunkel, Jörn; Hänggi, Peter

    2005-09-01

    A theory for (1+3) -dimensional relativistic Brownian motion under the influence of external force fields is put forward. Starting out from a set of relativistically covariant, but multiplicative Langevin equations we describe the relativistic stochastic dynamics of a forced Brownian particle. The corresponding Fokker-Planck equations are studied in the laboratory frame coordinates. In particular, the stochastic integration prescription--i.e., the discretization rule dilemma--is elucidated (prepoint discretization rule versus midpoint discretization rule versus postpoint discretization rule). Remarkably, within our relativistic scheme we find that the postpoint rule (or the transport form) yields the only Fokker-Planck dynamics from which the relativistic Maxwell-Boltzmann statistics is recovered as the stationary solution. The relativistic velocity effects become distinctly more pronounced by going from one to three spatial dimensions. Moreover, we present numerical results for the asymptotic mean-square displacement of a free relativistic Brownian particle moving in 1+3 dimensions. PMID:16241514

  16. Bone transport using intramedullary fixation and a single flexible traction cable.

    PubMed

    Hyodo, A; Kotschi, H; Kambic, H; Muschler, G

    1996-04-01

    The transfixing wires used in the limb-lengthening and bone-transport procedures described by Ilizarov are the primary source of complications, including infection, restricted joint motion, and pain. In an attempt to eliminate the need for external fixation, a traction cable device was devised to perform a 3-cm bone transport in the canine femur using an interlocking intramedullary rod for fixation. Twelve dogs were divided into 2 groups. Transport began 7 days after osteotomy and continued at either 1 mm per day (n = 6) or 2 mm per day (n = 6). The in vivo peak force, resting force, and stiffness of the transport segment increased throughout distraction to a mean of 150 Newtons, 58 N, and 58 N per millimeter, respectively, at the time of docking. The regenerate and docking sites united in 10 of 12 dogs. Failure of the regenerate associated with deep infection around the rod occurred in 2 animals (17%). Modifications of this technique to reduce the risk of infection are discussed. This study confirms that intramedullary fixation is compatible with distraction osteogenesis and shows that a single traction cable can provide the force necessary for bone transport without transfixing wires in this setting. PMID:8998886

  17. α1 -AR agonist induced piloerection protects against the development of traction alopecia.

    PubMed

    Goren, Andy; Shapiro, Jerry; Sinclair, Rodney; Kovacevic, Maja; McCoy, John

    2016-05-01

    Traction alopecia is hair loss that occurs after persistent pulling (e.g., during cosmetic procedures) on the roots of hair over time. Unlike plucking, which is painful, persistent pulling may go unnoticed until a patient presents with either bald spots or diffuse telogen shedding. Each hair follicle in the scalp contains an arrector pili muscle that, when contracted, erects the hair. The smooth muscle in the arrector pili expresses α1 adrenergic receptors (α1 -AR). As such, we hypothesized that contraction of the arrector pili muscle via an α1 -AR agonist would increase the threshold of force required to pluck hair during cosmetic procedures. Female subjects, ages 18-40, were recruited to study the effect of topically applied phenylephrine, a selective α1 -AR agonist, on epilation force and hair shedding during cosmetic procedures. In our blinded study, 80% of subjects demonstrated reduced shedding on days using phenylephrine compared to days using a placebo solution. The average reduction in hair loss was approximately 42%. In addition, the force threshold required for epilation increased by approximately 172% following topical phenylephrine application. To our knowledge this is the first study demonstrating the utility of α1 -AR agonists in the treatment of traction alopecia and hair shedding during cosmetic procedures. PMID:26678522

  18. The 3-dimensional cellular automata for HIV infection

    NASA Astrophysics Data System (ADS)

    Mo, Youbin; Ren, Bin; Yang, Wencao; Shuai, Jianwei

    2014-04-01

    The HIV infection dynamics is discussed in detail with a 3-dimensional cellular automata model in this paper. The model can reproduce the three-phase development, i.e., the acute period, the asymptotic period and the AIDS period, observed in the HIV-infected patients in a clinic. We show that the 3D HIV model performs a better robustness on the model parameters than the 2D cellular automata. Furthermore, we reveal that the occurrence of a perpetual source to successively generate infectious waves to spread to the whole system drives the model from the asymptotic state to the AIDS state.

  19. Advantages of diabetic tractional retinal detachment repair

    PubMed Central

    Sternfeld, Amir; Axer-Siegel, Ruth; Stiebel-Kalish, Hadas; Weinberger, Dov; Ehrlich, Rita

    2015-01-01

    Purpose To evaluate the outcomes and complications of patients with diabetic tractional retinal detachment (TRD) treated with pars plana vitrectomy (PPV). Patients and methods We retrospectively studied a case series of 24 eyes of 21 patients at a single tertiary, university-affiliated medical center. A review was carried out on patients who underwent PPV for the management of TRD due to proliferative diabetic retinopathy from October 2011 to November 2013. Preoperative and final visual outcomes, intraoperative and postoperative complications, and medical background were evaluated. Results A 23 G instrumentation was used in 23 eyes (95.8%), and a 25 G instrumentation in one (4.2%). Mean postoperative follow-up time was 13.3 months (4–30 months). Visual acuity significantly improved from logarithm of the minimum angle of resolution (LogMAR) 1.48 to LogMAR 1.05 (P<0.05). Visual acuity improved by ≥3 lines in 75% of patients. Intraoperative complications included iatrogenic retinal breaks in seven eyes (22.9%) and vitreal hemorrhage in nine eyes (37.5%). In two eyes, one sclerotomy was enlarged to 20 G (8.3%). Postoperative complications included reoperation in five eyes (20.8%) due to persistent subretinal fluid (n=3), vitreous hemorrhage (n=1), and dislocated intraocular lens (n=1). Thirteen patients (54.2%) had postoperative vitreous hemorrhage that cleared spontaneously, five patients (20.8%) required antiglaucoma medications for increased intraocular pressure, seven patients (29.2%) developed an epiretinal membrane, and two patients (8.3%) developed a macular hole. Conclusion Patients with diabetic TRD can benefit from PPV surgery. Intraoperative and postoperative complications can be attributed to the complexity of this disease. PMID:26604667

  20. Traction sheave elevator, hoisting unit and machine space

    DOEpatents

    Hakala, Harri; Mustalahti, Jorma; Aulanko, Esko

    2000-01-01

    Traction sheave elevator consisting of an elevator car moving along elevator guide rails, a counterweight moving along counterweight guide rails, a set of hoisting ropes (3) on which the elevator car and counterweight are suspended, and a drive machine unit (6) driving a traction sheave (7) acting on the hoisting ropes (3) and placed in the elevator shaft. The drive machine unit (6) is of a flat construction. A wall of the elevator shaft is provided with a machine space with its open side facing towards the shaft, the essential parts of the drive machine unit (6) being placed in the space. The hoisting unit (9) of the traction sheave elevator consists of a substantially discoidal drive machine unit (6) and an instrument panel (8) mounted on the frame (20) of the hoisting unit.

  1. An advanced pitch change mechanism incorporating a hybrid traction drive

    NASA Technical Reports Server (NTRS)

    Steinetz, B. M.; Sargisson, D. F.; White, G.; Loewenthal, S. H.

    1984-01-01

    A design of a propeller pitch control mechanism is described that meets the demanding requirements of a high-power, advanced turboprop. In this application, blade twisting moment torque can be comparable to that of the main reduction gearbox output: precise pitch control, reliability and compactness are all at a premium. A key element in the design is a compact, high-ratio hybrid traction drive which offers low torque ripple and high torsional stiffness. The traction drive couples a high speed electric motor/alternator unit to a ball screw that actuates the blade control links. The technical merits of this arrangement and the performance characteristics of the traction drive are discussed. Comparisons are made to the more conventional pitch control mechanisms.

  2. Re-adhesion control for a railway single wheelset test rig based on the behaviour of the traction motor

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Liang, B.

    2013-08-01

    A method for detecting wheel slip/slide and re-adhesion control of AC traction motors in railway applications is presented in this paper. This enables a better utilisation of available adhesion and could also reduce wheel wear by reducing high creep values. With this method, the wheel-rail (roller) creepage, creep force and friction coefficient can be indirectly detected and estimated by measuring the voltage, current and speed of the AC traction motor and using an extended Kalman filter. The re-adhesion controller is designed to regulate the motor torque command according to the maximum available adhesion based on the estimated results. Simulations under different friction coefficients are carried out to test the proposed method.

  3. 3-Dimensional Imaging Modalities for Phenotyping Genetically Engineered Mice

    PubMed Central

    Powell, K. A.; Wilson, D.

    2013-01-01

    A variety of 3-dimensional (3D) digital imaging modalities are available for whole-body assessment of genetically engineered mice: magnetic resonance microscopy (MRM), X-ray microcomputed tomography (microCT), optical projection tomography (OPT), episcopic and cryoimaging, and ultrasound biomicroscopy (UBM). Embryo and adult mouse phenotyping can be accomplished at microscopy or near microscopy spatial resolutions using these modalities. MRM and microCT are particularly well-suited for evaluating structural information at the organ level, whereas episcopic and OPT imaging provide structural and functional information from molecular fluorescence imaging at the cellular level. UBM can be used to monitor embryonic development longitudinally in utero. Specimens are not significantly altered during preparation, and structures can be viewed in their native orientations. Technologies for rapid automated data acquisition and high-throughput phenotyping have been developed and continually improve as this exciting field evolves. PMID:22146851

  4. Parallel manipulator robot assisted femoral fracture reduction on traction table.

    PubMed

    Lin, H; Wang, J Q; Han, W

    2013-01-01

    The principle of femoral shaft fracture reduction is to restore its pre-fractured limb length and mechanical axis. The current documented treatment method with traction table reduction does not conform to the quantitative alignment and reduction. There is also a great amount of X-Ray radiation exposure to both surgeon and patient during the procedure. For this reason, we introduced an innovated Parallel Manipulator Robot (PMR) application: A Femoral Shaft Fracture Reduction with Parallel Manipulator Robot on Traction Table. With this application, the quantitative control on fracture reduction and alignment can be achieved and the radiation exposure to both surgeons and patients can be greatly reduced. PMID:24110820

  5. Evaluation of a high performance fixed-ratio traction drive

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Anderson, N. E.; Rohn, D. A.

    1980-01-01

    The results of a test program to evaluate a compact, high performance, fixed ratio traction drive are presented. This transmission, the Nasvytis Multiroller Traction Drive, is a fixed ratio, single stage planetary with two rows of stepped planet rollers. Two versions of the drive were parametrically tested back-to-back at speeds to 73,000 rpm and power levels to 180 kW (240 hp). Parametric tests were also conducted with the Nasvytis drive retrofitted to an automotive gas turbine engine. The drives exhibited good performance, with a nominal peak efficiency of 94 to 96 percent and a maximum speed loss due to creep of approximately 3.5 percent.

  6. Protalign: a 3-dimensional protein alignment assessment tool.

    PubMed

    Meads, D; Hansen, M D; Pang, A

    1999-01-01

    Protein fold recognition (sometimes called threading) is the prediction of a protein's 3-dimensional shape based on its similarity to a protein of known structure. Fold predictions are low resolution; that is, no effort is made to rotate the protein's component amino acid side chains into their correct spatial orientations. The goal is simply to recognize the protein family member that most closely resembles the target sequence of unknown structure and to create a sensible alignment of the target to the known structure (i.e., a structure-sequence alignment). To facilitate this type of structure prediction, we have designed a low resolution molecular graphics tool. ProtAlign introduces the ability to interact with and edit alignments directly in the 3-dimensional structure as well as in the usual 2-dimensional layout. It also contains several functions and features to help the user assess areas within the alignment. ProtAlign implements an open pipe architecture to allow other programs to access its molecular graphics capabilities. In addition, it is capable of "driving" other programs. Because amino acid side chain orientation is not relevant in fold recognition, we represent amino acid residues as abstract shapes or glyphs much like Lego (tm) blocks and we borrow techniques from comparative flow visualization using streamlines to provide clean depictions of the entire protein model. By creating a low resolution representation of protein structure, we are able to at least double the amount of information on the screen. At the same time, we create a view that is not as busy as the corresponding representations using traditional high resolution visualization methods which show detailed atomic structure. This eliminates distracting and possibly misleading visual clutter resulting from the mapping of protein alignment information onto a high resolution display of the known structure. This molecular graphics program is implemented in Open GL to facilitate porting to

  7. Candidate Coatings and Dry Traction Drives for Planetary Vehicles

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert; Oswald, Fred B.

    2002-01-01

    Robert Fusaro and Fred Oswald of the Mechanical Components Branch discussed 'Candidate Coatings and Dry Traction Drives for Planetary Vehicles'. Vehicles to be designed for exploration of planets and moons of the solar system will require reliable mechanical drives to operate efficiently. Long-term operation of these drives will be challenging because of extreme operating conditions. These extreme conditions include: very high and/or very cold temperatures, wide temperature ranges, dust, vacuum or low-pressure atmospheres, and corrosive environments. Most drives used on Earth involve oil-lubricated gears. However, due to the extreme conditions on planetary surfaces, it may not be advisable or even possible to use oil lubrication. Unfortunately, solid lubricants do not work well when applied to gears because of the high contact stress conditions and large sliding motion between the teeth, which cause wear and limit life. We believe traction drives will provide an attractive alternative to gear drives. Traction drives are composed of rollers that provide geometry more conducive to solid lubrication. Minimal slip occurs in this contact geometry and thus there is very low wear to the solid lubricant. The challenge for these solid-lubricated drives is finding materials or coatings that provide the required long-life while also providing high traction. We seek materials that provide low wear with high friction.

  8. 21 CFR 890.5900 - Power traction equipment.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Power traction equipment. 890.5900 Section 890.5900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5900 Power...

  9. 21 CFR 890.5900 - Power traction equipment.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Power traction equipment. 890.5900 Section 890.5900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5900 Power...

  10. 21 CFR 890.5900 - Power traction equipment.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Power traction equipment. 890.5900 Section 890.5900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5900 Power...

  11. 21 CFR 890.5900 - Power traction equipment.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Power traction equipment. 890.5900 Section 890.5900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5900 Power...

  12. Animal Traction. Appropriate Technologies for Development. Manual M-12.

    ERIC Educational Resources Information Center

    Watson, Peter R.

    This manual is designed for use by Peace Corps volunteers and agricultural extension personnel working in animal traction development programs. While some of the information contained in the manual is specific to the extension of animal-powered agriculture in Africa, the principles covered are generally applicable wherever the method is being used…

  13. 21 CFR 890.5900 - Power traction equipment.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Power traction equipment. 890.5900 Section 890.5900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5900 Power...

  14. Apicotomy as treatment for failure of orthodontic traction.

    PubMed

    Osório, Leandro Berni; Ferrazzo, Vilmar Antonio; Serpa, Geraldo; Ferrazzo, Kívia Linhares

    2013-01-01

    Objective. The purpose of this study was to present a case report that demonstrated primary failure in a tooth traction that was subsequently treated with apicotomy technique. Case Report. A 10-year-old girl had an impacted upper right canine with increased pericoronal space, which was apparent on a radiographic image. The right maxillary sinus showed an opacity suggesting sinusitis. The presumptive diagnosis was dentigerous cyst associated with maxillary sinus infection. The plan for treatment included treatment of the sinus infection and cystic lesion and orthodontic traction of the canine after surgical exposure and bonding of an orthodontic appliance. The surgical procedure, canine position, root dilaceration, and probably apical ankylosis acted in the primary failure of the orthodontic traction. Surgical apical cut of the displaced teeth was performed, and tooth position in the dental arch was possible, with a positive response to the pulp vitality test. Conclusion. Apicotomy is an effective technique to treat severe canine displacement and primary orthodontic traction failure of palatally displaced canines. PMID:24383010

  15. Macrophages Mediate the Repair of Brain Vascular Rupture through Direct Physical Adhesion and Mechanical Traction.

    PubMed

    Liu, Chi; Wu, Chuan; Yang, Qifen; Gao, Jing; Li, Li; Yang, Deqin; Luo, Lingfei

    2016-05-17

    Hemorrhagic stroke and brain microbleeds are caused by cerebrovascular ruptures. Fast repair of such ruptures is the most promising therapeutic approach. Due to a lack of high-resolution in vivo real-time studies, the dynamic cellular events involved in cerebrovascular repair remain unknown. Here, we have developed a cerebrovascular rupture system in zebrafish by using multi-photon laser, which generates a lesion with two endothelial ends. In vivo time-lapse imaging showed that a macrophage arrived at the lesion and extended filopodia or lamellipodia to physically adhere to both endothelial ends. This macrophage generated mechanical traction forces to pull the endothelial ends and facilitate their ligation, thus mediating the repair of the rupture. Both depolymerization of microfilaments and inhibition of phosphatidylinositide 3-kinase or Rac1 activity disrupted macrophage-endothelial adhesion and impaired cerebrovascular repair. Our study reveals a hitherto unexpected role for macrophages in mediating repair of cerebrovascular ruptures through direct physical adhesion and mechanical traction. PMID:27156384

  16. Idiopathic vitreomacular traction and macular hole: a comprehensive review of pathophysiology, diagnosis, and treatment

    PubMed Central

    Steel, D H W; Lotery, A J

    2013-01-01

    Posterior vitreous detachment (PVD) is a common phenomenon in the aging eye. However, this may be complicated by persistent symptomatic vitreomacular adhesions that exert tractional forces on the macula (vitreomacular traction; VMT). VMT itself may be associated with epiretinal membrane formation and the development of idiopathic macular holes (IMH). Such pathologies may cause visual disturbances, including metamorphopsia, photopsia, blurred vision, and decreased visual acuity, which impact an individual's quality of life. Technologies such as optical coherence tomography allow an increasingly more accurate visualisation of the macular anatomy, including quantification of macular hole characteristics, and this facilitates treatment decision-making. Pars plana vitrectomy remains the primary treatment option for many patients with VMT or IMH; for the latter, peeling of the inner limiting membrane (ILM) of the retina has shown improved outcomes when compared with no ILM peeling. The development of narrow-gauge transconjunctival vitrectomy systems has improved the rate of visual recovery following surgery. Ocriplasmin, by degrading laminin and fibronectin at the vitreoretinal interface, may allow induction of PVD in a non-invasive manner. Indeed, clinical studies have supported its use as an alternative to surgery in certain patient populations. However, further research is still needed with respect to greater understanding of the pathophysiology underlying the development of VMT and IMH. PMID:24108069

  17. Recurrent carpal tunnel syndrome, epineural fibrous fixation, and traction neuropathy.

    PubMed

    Hunter, J M

    1991-08-01

    This article has reviewed recurrent carpal tunnel syndrome, epineural fibrous fixation, and traction neuropathy of the median nerve. The problems surrounding the diagnosis and treatment of recurrent CTS have been discussed at length. The percent of failures from traditional open ligament surgery is observed to be high, and will become more prevalent as more casual treatments are carried out. This article makes a positive statement with reference to mobilization of the median nerve and anatomic restoration of the transverse carpal ligament. Fibrous fixation of the median nerve is a product of life and function. All cases are different, reflecting the strength, abilities, and personalities of the patients. A bottom line is drawn on these patients, where the summation of the problems of life become symptomatic and disabling. Epineural fibrous fixations induce median nerve traction, governed by hand, wrist, and forearm movements. Traction and tension suggest the intermittent disturbance of nerve nutrition and nerve conduction as the elastic limits of the nerve are approached. These factors accumulate and, in time, cause traction neuropathies with pain. This is followed by a reduced work capability. This impairment can be reversed by surgical nerve mobilization followed by functional nerve gliding therapy. A background history injury to the hand and wrist may be significant, as well as factors such as overuse and misuse of the hand and extremity. Prior to surgery, the careful application of diagnostic stress tests are essential, for the differential diagnosis of fixation traction and positional peripheral neuropathies. Nerve mobilization supported by magnification and the techniques of hand surgery has been successful by the methods discussed and has permitted, importantly, the restoration of the anatomic retinaculum for the flexor tendon system. This can be restored in carpal tunnel surgery and reconstructed with basic ligament material in recurrent carpal tunnel

  18. Chromosome Conformation of Human Fibroblasts Grown in 3-Dimensional Spheroids

    PubMed Central

    Chen, Haiming; Comment, Nicholas; Chen, Jie; Ronquist, Scott; Hero, Alfred; Ried, Thomas; Rajapakse, Indika

    2015-01-01

    In the study of interphase chromosome organization, genome-wide chromosome conformation capture (Hi-C) maps are often generated using 2-dimensional (2D) monolayer cultures. These 2D cells have morphological deviations from cells that exist in 3-dimensional (3D) tissues in vivo, and may not maintain the same chromosome conformation. We used Hi-C maps to test the extent of differences in chromosome conformation between human fibroblasts grown in 2D cultures and those grown in 3D spheroids. Significant differences in chromosome conformation were found between 2D cells and those grown in spheroids. Intra-chromosomal interactions were generally increased in spheroid cells, with a few exceptions, while inter-chromosomal interactions were generally decreased. Overall, chromosomes located closer to the nuclear periphery had increased intra-chromosomal contacts in spheroid cells, while those located more centrally had decreased interactions. This study highlights the necessity to conduct studies on the topography of the interphase nucleus under conditions that mimic an in vivo environment. PMID:25738643

  19. Thermal crosstalk in 3-dimensional RRAM crossbar array.

    PubMed

    Sun, Pengxiao; Lu, Nianduan; Li, Ling; Li, Yingtao; Wang, Hong; Lv, Hangbing; Liu, Qi; Long, Shibing; Liu, Su; Liu, Ming

    2015-01-01

    High density 3-dimensional (3D) crossbar resistive random access memory (RRAM) is one of the major focus of the new age technologies. To compete with the ultra-high density NAND and NOR memories, understanding of reliability mechanisms and scaling potential of 3D RRAM crossbar array is needed. Thermal crosstalk is one of the most critical effects that should be considered in 3D crossbar array application. The Joule heat generated inside the RRAM device will determine the switching behavior itself, and for dense memory arrays, the temperature surrounding may lead to a consequent resistance degradation of neighboring devices. In this work, thermal crosstalk effect and scaling potential under thermal effect in 3D RRAM crossbar array are systematically investigated. It is revealed that the reset process is dominated by transient thermal effect in 3D RRAM array. More importantly, thermal crosstalk phenomena could deteriorate device retention performance and even lead to data storage state failure from LRS (low resistance state) to HRS (high resistance state) of the disturbed RRAM cell. In addition, the resistance state degradation will be more serious with continuously scaling down the feature size. Possible methods for alleviating thermal crosstalk effect while further advancing the scaling potential are also provided and verified by numerical simulation. PMID:26310537

  20. Thermal crosstalk in 3-dimensional RRAM crossbar array

    PubMed Central

    Sun, Pengxiao; Lu, Nianduan; Li, Ling; Li, Yingtao; Wang, Hong; Lv, Hangbing; Liu, Qi; Long, Shibing; Liu, Su; Liu, Ming

    2015-01-01

    High density 3-dimensional (3D) crossbar resistive random access memory (RRAM) is one of the major focus of the new age technologies. To compete with the ultra-high density NAND and NOR memories, understanding of reliability mechanisms and scaling potential of 3D RRAM crossbar array is needed. Thermal crosstalk is one of the most critical effects that should be considered in 3D crossbar array application. The Joule heat generated inside the RRAM device will determine the switching behavior itself, and for dense memory arrays, the temperature surrounding may lead to a consequent resistance degradation of neighboring devices. In this work, thermal crosstalk effect and scaling potential under thermal effect in 3D RRAM crossbar array are systematically investigated. It is revealed that the reset process is dominated by transient thermal effect in 3D RRAM array. More importantly, thermal crosstalk phenomena could deteriorate device retention performance and even lead to data storage state failure from LRS (low resistance state) to HRS (high resistance state) of the disturbed RRAM cell. In addition, the resistance state degradation will be more serious with continuously scaling down the feature size. Possible methods for alleviating thermal crosstalk effect while further advancing the scaling potential are also provided and verified by numerical simulation. PMID:26310537

  1. 77 FR 56910 - Iowa Traction Railway Company-Acquisition and Operation Exemption-Rail Line of Iowa Traction...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Surface Transportation Board Iowa Traction Railway Company--Acquisition and Operation Exemption--Rail Line... pleadings, referring to Docket No. FD 35670, must be filed with the Surface Transportation Board, 395...

  2. Retinal Changes Induced by Epiretinal Tangential Forces

    PubMed Central

    Romano, Mario R.; Comune, Chiara; Ferrara, Mariantonia; Cennamo, Gilda; De Cillà, Stefano; Toto, Lisa; Cennamo, Giovanni

    2015-01-01

    Two kinds of forces are active in vitreoretinal traction diseases: tangential and anterior-posterior forces. However, tangential forces are less characterized and classified in literature compared to the anterior-posterior ones. Tangential epiretinal forces are mainly due to anomalous posterior vitreous detachment (PVD), vitreoschisis, vitreopapillary adhesion (VPA), and epiretinal membranes (ERMs). Anomalous PVD plays a key role in the formation of the tangential vectorial forces on the retinal surface as consequence of gel liquefaction (synchysis) without sufficient and fast vitreous dehiscence at the vitreoretinal interface. The anomalous and persistent adherence of the posterior hyaloid to the retina can lead to vitreomacular/vitreopapillary adhesion or to a formation of avascular fibrocellular tissue (ERM) resulting from the proliferation and transdifferentiation of hyalocytes resident in the cortical vitreous remnants after vitreoschisis. The right interpretation of the forces involved in the epiretinal tangential tractions helps in a better definition of diagnosis, progression, prognosis, and surgical outcomes of vitreomacular interfaces. PMID:26421183

  3. Video Based Sensor for Tracking 3-Dimensional Targets

    NASA Technical Reports Server (NTRS)

    Howard, R. T.; Book, Michael L.; Bryan, Thomas C.

    2000-01-01

    Video-Based Sensor for Tracking 3-Dimensional Targets The National Aeronautics and Space Administration's (NASAs) Marshall Space Flight Center (MSFC) has been developing and testing video-based sensors for automated spacecraft guidance for several years, and the next generation of video sensor will have tracking rates up to 100 Hz and will be able to track multiple reflectors and targets. The Video Guidance Sensor (VGS) developed over the past several years has performed well in testing and met the objective of being used as the terminal guidance sensor for an automated rendezvous and capture system. The first VGS was successfully tested in closed-loop 3-degree-of-freedom (3- DOF) tests in 1989 and then in 6-DOF open-loop tests in 1992 and closed-loop tests in 1993-4. Development and testing continued, and in 1995 approval was given to test the VGS in an experiment on the Space Shuttle. The VGS flew in 1997 and in 1998, performing well for both flights. During the development and testing before, during, and after the flight experiments, numerous areas for improvement were found. The VGS was developed with a sensor head and an electronics box, connected by cables. The VGS was used in conjunction with a target that had wavelength-filtered retro-reflectors in a specific pattern, The sensor head contained the laser diodes, video camera, and heaters and coolers. The electronics box contained a frame grabber, image processor, the electronics to control the components in the sensor head, the communications electronics, and the power supply. The system works by sequentially firing two different wavelengths of laser diodes at the target and processing the two images. Since the target only reflects one wavelength, it shows up well in one image and not at all in the other. Because the target's dimensions are known, the relative positions and attitudes of the target and the sensor can be computed from the spots reflected from the target. The system was designed to work from I

  4. Development and Validation of a 3-Dimensional CFB Furnace Model

    NASA Astrophysics Data System (ADS)

    Vepsäläinen, Arl; Myöhänen, Karl; Hyppäneni, Timo; Leino, Timo; Tourunen, Antti

    At Foster Wheeler, a three-dimensional CFB furnace model is essential part of knowledge development of CFB furnace process regarding solid mixing, combustion, emission formation and heat transfer. Results of laboratory and pilot scale phenomenon research are utilized in development of sub-models. Analyses of field-test results in industrial-scale CFB boilers including furnace profile measurements are simultaneously carried out with development of 3-dimensional process modeling, which provides a chain of knowledge that is utilized as feedback for phenomenon research. Knowledge gathered by model validation studies and up-to-date parameter databases are utilized in performance prediction and design development of CFB boiler furnaces. This paper reports recent development steps related to modeling of combustion and formation of char and volatiles of various fuel types in CFB conditions. Also a new model for predicting the formation of nitrogen oxides is presented. Validation of mixing and combustion parameters for solids and gases are based on test balances at several large-scale CFB boilers combusting coal, peat and bio-fuels. Field-tests including lateral and vertical furnace profile measurements and characterization of solid materials provides a window for characterization of fuel specific mixing and combustion behavior in CFB furnace at different loads and operation conditions. Measured horizontal gas profiles are projection of balance between fuel mixing and reactions at lower part of furnace and are used together with both lateral temperature profiles at bed and upper parts of furnace for determination of solid mixing and combustion model parameters. Modeling of char and volatile based formation of NO profiles is followed by analysis of oxidizing and reducing regions formed due lower furnace design and mixing characteristics of fuel and combustion airs effecting to formation ofNO furnace profile by reduction and volatile-nitrogen reactions. This paper presents

  5. The 3-dimensional construction of the Rae craton, central Canada

    NASA Astrophysics Data System (ADS)

    Snyder, David B.; Craven, James A.; Pilkington, Mark; Hillier, Michael J.

    2015-10-01

    Reconstruction of the 3-dimensional tectonic assembly of early continents, first as Archean cratons and then Proterozoic shields, remains poorly understood. In this paper, all readily available geophysical and geochemical data are assembled in a 3-D model with the most accurate bedrock geology in order to understand better the geometry of major structures within the Rae craton of central Canada. Analysis of geophysical observations of gravity and seismic wave speed variations revealed several lithospheric-scale discontinuities in physical properties. Where these discontinuities project upward to correlate with mapped upper crustal geological structures, the discontinuities can be interpreted as shear zones. Radiometric dating of xenoliths provides estimates of rock types and ages at depth beneath sparse kimberlite occurrences. These ages can also be correlated to surface rocks. The 3.6-2.6 Ga Rae craton comprises at least three smaller continental terranes, which "cratonized" during a granitic bloom. Cratonization probably represents final differentiation of early crust into a relatively homogeneous, uniformly thin (35-42 km), tonalite-trondhjemite-granodiorite crust with pyroxenite layers near the Moho. The peak thermotectonic event at 1.86-1.7 Ga was associated with the Hudsonian orogeny that assembled several cratons and lesser continental blocks into the Canadian Shield using a number of southeast-dipping megathrusts. This orogeny metasomatized, mineralized, and recrystallized mantle and lower crustal rocks, apparently making them more conductive by introducing or concentrating sulfides or graphite. Little evidence exists of thin slabs similar to modern oceanic lithosphere in this Precambrian construction history whereas underthrusting and wedging of continental lithosphere is inferred from multiple dipping discontinuities.

  6. A 3-Dimensional Anatomic Study of the Distal Biceps Tendon

    PubMed Central

    Walton, Christine; Li, Zhi; Pennings, Amanda; Agur, Anne; Elmaraghy, Amr

    2015-01-01

    Background Complete rupture of the distal biceps tendon from its osseous attachment is most often treated with operative intervention. Knowledge of the overall tendon morphology as well as the orientation of the collagenous fibers throughout the musculotendinous junction are key to intraoperative decision making and surgical technique in both the acute and chronic setting. Unfortunately, there is little information available in the literature. Purpose To comprehensively describe the morphology of the distal biceps tendon. Study Design Descriptive laboratory study. Methods The distal biceps terminal musculature, musculotendinous junction, and tendon were digitized in 10 cadaveric specimens and data reconstructed using 3-dimensional modeling. Results The average length, width, and thickness of the external distal biceps tendon were found to be 63.0, 6.0, and 3.0 mm, respectively. A unique expansion of the tendon fibers within the distal muscle was characterized, creating a thick collagenous network along the central component between the long and short heads. Conclusion This study documents the morphologic parameters of the native distal biceps tendon. Reconstruction may be necessary, especially in chronic distal biceps tendon ruptures, if the remaining tendon morphology is significantly compromised compared with the native distal biceps tendon. Knowledge of normal anatomical distal biceps tendon parameters may also guide the selection of a substitute graft with similar morphological characteristics. Clinical Relevance A thorough description of distal biceps tendon morphology is important to guide intraoperative decision making between primary repair and reconstruction and to better select the most appropriate graft. The detailed description of the tendinous expansion into the muscle may provide insight into better graft-weaving and suture-grasping techniques to maximize proximal graft incorporation. PMID:26665092

  7. Traction radiographs in the diagnosis of chronic wrist pain.

    PubMed

    Fortems, Y; Mawhinney, I; Lawrence, T; Stanley, J K

    1994-06-01

    A sensitive non-invasive diagnostic test for intrinsic ligament rupture in patients with chronic wrist pain has still to be found. Differential displacement of the scaphoid, lunate and triquetrum can in some instances be seen during arthroscopy of acute wrist injuries and also on overdistraction of distal radial fractures with an external fixator. We performed a prospective study on 20 patients with chronic wrist pain using 2 kg and 5 kg traction radiographs without and with the addition of an ischaemic block, to assess differential displacement as a diagnostic criterion for intrinsic ligament rupture. Arthroscopy was used as arbiter of diagnosis. The sensitivity ranged from 14% to 57% and the specificity ranged from 53.7% to 100% according to the amount of traction and ischaemic block. In view of these poor results we conclude the stretch test has no additional value in the preoperative assessment of chronic wrist pain. PMID:8077822

  8. Traction drive automatic transmission for gas turbine engine driveline

    DOEpatents

    Carriere, Donald L.

    1984-01-01

    A transaxle driveline for a wheeled vehicle has a high speed turbine engine and a torque splitting gearset that includes a traction drive unit and a torque converter on a common axis transversely arranged with respect to the longitudinal centerline of the vehicle. The drive wheels of the vehicle are mounted on a shaft parallel to the turbine shaft and carry a final drive gearset for driving the axle shafts. A second embodiment of the final drive gearing produces an overdrive ratio between the output of the first gearset and the axle shafts. A continuously variable range of speed ratios is produced by varying the position of the drive rollers of the traction unit. After starting the vehicle from rest, the transmission is set for operation in the high speed range by engaging a first lockup clutch that joins the torque converter impeller to the turbine for operation as a hydraulic coupling.

  9. Fabrication of Superconducting Traction Transformer for Railway Rolling Stock

    NASA Astrophysics Data System (ADS)

    Kamijo, H.; Hata, H.; Fujimoto, H.; Inoue, A.; Nagashima, K.; Ikeda, K.; Yamada, H.; Sanuki, Y.; Tomioka, A.; Uwamori, K.; Yoshida, S.; Iwakuma, M.; Funaki, K.

    2006-06-01

    We designed a floor type single-phase 4 MVA superconducting traction transformer for Shinkansen rolling stock. In this study, we fabricated a prototype superconducting traction transformer based on this design. This transformer of the core-type design has a primary winding, four secondary windings and a tertiary winding. The windings are wound by Bi2223 superconducting tapes and cooled by subcooled liquid nitrogen. The core is kept at room temperature. The cryostat is made of GFRP with two holes to pass core legs through. The outer dimensions are about 1.2m × 0.7m × 1.9m excluding the compressor. Its weight is 1.71t excluding that of refrigerator and compressor. The transformer was tested according to Japanese Industrial Standards (JIS)-E5007. We confirmed that the performance of transformer has been achieved almost exactly as planned. The rated capacity is equivalent to 3.5MVA in the superconducting state.

  10. Design study of toroidal traction CVT for electric vehicles

    NASA Technical Reports Server (NTRS)

    Raynard, A. E.; Kraus, J.; Bell, D. D.

    1980-01-01

    The development, evaluation, and optimization of a preliminary design concept for a continuously variable transmission (CVT) to couple the high-speed output shaft of an energy storage flywheel to the drive train of an electric vehicle is discussed. An existing computer simulation program was modified and used to compare the performance of five CVT design configurations. Based on this analysis, a dual-cavity full-toroidal drive with regenerative gearing is selected for the CVT design configuration. Three areas are identified that will require some technological development: the ratio control system, the traction fluid properities, and evaluation of the traction contact performance. Finally, the suitability of the selected CVT design concept for alternate electric and hybrid vehicle applications and alternate vehicle sizes and maximum output torques is determined. In all cases the toroidal traction drive design concept is applicable to the vehicle system. The regenerative gearing could be eliminated in the electric powered vehicle because of the reduced ratio range requirements. In other cases the CVT with regenerative gearing would meet the design requirements after appropriate adjustments in size and reduction gearing ratio.

  11. Thermal traction contact performance evaluation under fully flooded and starved conditions

    NASA Technical Reports Server (NTRS)

    Tevaarwerk, J. L.

    1985-01-01

    Ultra high speed traction tests were performed on two traction fluids commonly employed. Traction data on these fluids is required for purposes of traction drive design optimization techniques. To obtain the traction data, an existing twin disc traction test machine was employed. This machine was modified to accommodate the range of test variables. All the data reported was obtained under conditions of side slip, a technique whereby only low power levels are required to simulate real traction drive contacts. Theoretical traction predictions were performed for a representative number of curves that showed the influence of rolling velocity, of contact pressure and of aspect ratio. To establish the accuracy of the thermal model the predictions were performed ith increasing levels of independence of experimentally determined parameters. In the final resulting prediction only two non linear thermal parameters were used for the prediction of 15 different traction curves covering the entire range of variables as used in the investigation, with the exception of the influence of asperity traction. Comparison of these theoretical curves and corresponding experimental traces show very good agreement.

  12. The measurement, modeling, and prediction of traction for rocket propellant 1

    NASA Technical Reports Server (NTRS)

    Tevaarwerk, J. L.

    1989-01-01

    Traction tests were performed on RP-1, a common kerosene based rocket propellant. Traction data on this fluid are required for purposes of turbopump bearing design, using codes such as SHABERTH. To obtain the traction data, an existing twin disc machine was used, operating under the side slip mode and using elliptical contacts. The range of test variables were: contact peak Hertz stress from 1.0 to 2.0 GPa, disc surface speed from 10 to 50 m/s, fluid inlet temperature from 30 to 70 C, and with a contact aspect ratio of 1.7. The resulting traction curves were reduced to fundamental fluid property parameters using the Johnson and Tevaarwerk traction model. Theoretical traction predictions were performed by back substitution of the fundamental properties into the traction model. Comparison of the predicted with the measured curves gives a high degree of confidence in the correctness of the traction model. For purposes of input to the NASA SHABERTH program, the traction model was next used to predict the expected traction of RP-1 under line contact conditions.

  13. A 3-dimensional Analysis of the Cassiopeia A Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Isensee, Karl

    We present a multi-wavelength study of the nearby supernova remnant Cassiopeia A (Cas A). Easily resolvable supernova remnants such as Cas A provide a unique opportunity to test supernova explosion models. Additionally, we can observe key processes in the interstellar medium as the ejecta from the initial explosion encounter Cas A's powerful shocks. In order to accomplish these science goals, we used the Spitzer Space Telescope's Infrared Spectrograph to create a high resolution spectral map of select regions of Cas A, allowing us to make a Doppler reconstruction of its 3-dimensional structure structure. In the center of the remnant, we find relatively pristine ejecta that have not yet reached Cas A's reverse shock or interacted with the circumstellar environment. We observe O, Si, and S emission. These ejecta can form both sheet-like structures as well as filaments. Si and O, which come from different nucleosynthetic layers of the star, are observed to be coincident in some regions, and separated by >500 km s -1 in others. Observed ejecta traveling toward us are, on average, ˜800 km s -1 slower than the material traveling away from us. We compare our observations to recent supernova explosion models and find that no single model can simultaneously reproduce all the observed features. However, models of different supernova explosions can collectively produce the observed geometries and structures of the emission interior to Cas A's reverse shock. We use the results from the models to address the conditions during the supernova explosion, concentrating on asymmetries in the shock structure. We also predict that the back surface of Cassiopeia A will begin brightening in ∼30 years, and the front surface in ˜100 years. We then used similar observations from 3 regions on Cas A's reverse shock in order to create more 3-dimensional maps. In these regions, we observe supernova ejecta both immediately before and during the shock-ejecta interaction. We determine that the

  14. Enzymatic vitreolysis with recombinant tissue plasminogen activator for vitreomacular traction

    PubMed Central

    Raczyńska, Dorota; Lipowski, Paweł; Zorena, Katarzyna; Skorek, Andrzej; Glasner, Paulina

    2015-01-01

    Aims The aim of our research was to gain data about the efficacy of intravitreal injections of a recombinant tissue plasminogen activator (rTPA) in dissolving vitreoretinal tractions (VRTs). Materials and methods The study group consisted of patients of our Ophthalmology Clinic who had received an injection of rTPA (TPA Group) for an existent vitreomacular traction confirmed by optical coherence tomography and stereoscopic examinations. The control group consisted of patients who had declined treatment despite the existence of a vitreomacular traction confirmed by the same diagnostic methods. Each group consisted of 30 people (30 eyes). The observation period was 6 months. Conclusion In both groups some of the VRTs had dissolved. In the TPA group the traction dissolved in 10 patients (33.33%) and in the control group only in 5 (16.67%). It is also important to point out that the mean baseline membrane thickness was higher in the TPA group than in the control group. Observing patients in both groups we noticed that the dissolution of vitreoretinal membrane occurred most frequently in those cases where the membrane was thin. In the TPA group, the mean membrane thickness after 6 months decreased considerably. At the same time, no significant change in the membrane thickness could be observed in the control group. Observation of the retinal thickness allows us to draw the following conclusion: in the TPA group, the retinal thickness in the macular area (edema) had decreased over the study period, whereas in the control group it had increased. In those cases where the traction had dissolved, the edema of the retina decreased by the end of the 6-month period in both groups. In the TPA group, the dissolution of the membrane occurred most often within 3 months from the primary injection. Based on statistics, we can confirm that in the control group there was a decrease in visual acuity during the 6 months of the study period. At the same time, visual acuity in the TPA

  15. Method and apparatus for imaging through 3-dimensional tracking of protons

    NASA Technical Reports Server (NTRS)

    Ryan, James M. (Inventor); Macri, John R. (Inventor); McConnell, Mark L. (Inventor)

    2001-01-01

    A method and apparatus for creating density images of an object through the 3-dimensional tracking of protons that have passed through the object are provided. More specifically, the 3-dimensional tracking of the protons is accomplished by gathering and analyzing images of the ionization tracks of the protons in a closely packed stack of scintillating fibers.

  16. Fabrication and selective surface modification of 3-dimensionally textured biomedical polymers from etched silicon substrates.

    PubMed

    Kapur, R; Spargo, B J; Chen, M S; Calvert, J M; Rudolph, A S

    1996-01-01

    A new method is described for producing biomedically relevant polymers with precisely defined micron scale surface texture in the x, y, and z planes. Patterned Si templates were fabricated using photolithography to create a relief pattern in photoresist with lateral dimensions as small as 1 micron. Electroless Ni was selectively deposited in the trenches of the patterned substrate. The Ni served as a resilient mask for transferring the patterns onto the Si substrate to depths of up to 8.5 microns by anisotropic reactive ion etching with a fluorine-based plasma. The 3-dimensional (3-D) textured silicon substrates were used as robust, reusable molds for pattern transfer onto poly (dimethyl siloxane), low density poly (ethylene), poly (L-lactide), and poly (glycolide) by either casting or injection molding. The fidelity of the pattern transfer from the silicon substrates to the polymers was 90 to 95% in all three planes for all polymers for more than 60 transfers from a single wafer, as determined by scanning electron microscopy and atomic force microscopy. Further, the 3-D textured polymers were selectively modified to coat proteins either in the trenches or on the mesas by capillary modification or selective coating techniques. These selectively patterned 3-D polymer substrates may be useful for a variety of biomaterial applications. PMID:8953387

  17. Fabrication of a 3-dimensional nanostructured binary colloidal crystal within a confined channel.

    PubMed

    Gorey, Brian; Smyth, Malcolm R; Morrin, Aoife; White, Blánaid

    2014-12-15

    The reproducible fabrication of nanostructured 3Dimensional (3D) binary colloidal crystal (bCC) in a defined geometric space through a simple one step process is detailed. This method allows for the potential fabrication of a bCC in a sealed μchip within a defined area or channel by capillary forces, unlike other bCC formation methods such as dip-drawing, where the substrate must be submerged in a suspension to form a bCC, or bCC monolayers, which are fabricated at the water air interface. Through simple variation in volume fraction ratio (VF(S/L)) of nano-(denoted small, S) and macro-sized (denoted large, L) polystyrene (PS) spheres and diameter size ratio (D(S/L)), the manipulation of bCC structures was also achieved. Variation of nano-sized PS sphere number within the interstitial voids formed between neighbouring macro-sized spheres enabled the reproducible fabrication of LS2 and LS6 structures, which contain 1 and 3 nano-spheres respectively in each interstitial void. It must be noted that while VF(S/L) allows for control of the final LSn structure, thickness of bCC formation in this manner is independent of VFS/L. PMID:25268825

  18. The influence of surface dents and grooves on traction in sliding EHD point contacts

    NASA Technical Reports Server (NTRS)

    Cusano, C.; Wedeven, L. D.

    1982-01-01

    Changes in traction, caused by dents and grooves on a highly polished ball,are investigated as these defects approach and go through sliding elastohydrodynamic point contacts. The contacts are formed with the ball loading against a transparent disk. The ball and thus the topographical features are held stationary at various locations in the vicinity and within the contact while the disk is rotating. These topographical features can cause substantial changes in the traction when compared to traction obtained with smooth surfaces.

  19. Force sensing using 3D displacement measurements in linear elastic bodies

    NASA Astrophysics Data System (ADS)

    Feng, Xinzeng; Hui, Chung-Yuen

    2016-04-01

    In cell traction microscopy, the mechanical forces exerted by a cell on its environment is usually determined from experimentally measured displacement by solving an inverse problem in elasticity. In this paper, an innovative numerical method is proposed which finds the "optimal" traction to the inverse problem. When sufficient regularization is applied, we demonstrate that the proposed method significantly improves the widely used approach using Green's functions. Motivated by real cell experiments, the equilibrium condition of a slowly migrating cell is imposed as a set of equality constraints on the unknown traction. Our validation benchmarks demonstrate that the numeric solution to the constrained inverse problem well recovers the actual traction when the optimal regularization parameter is used. The proposed method can thus be applied to study general force sensing problems, which utilize displacement measurements to sense inaccessible forces in linear elastic bodies with a priori constraints.

  20. Force sensing using 3D displacement measurements in linear elastic bodies

    NASA Astrophysics Data System (ADS)

    Feng, Xinzeng; Hui, Chung-Yuen

    2016-07-01

    In cell traction microscopy, the mechanical forces exerted by a cell on its environment is usually determined from experimentally measured displacement by solving an inverse problem in elasticity. In this paper, an innovative numerical method is proposed which finds the "optimal" traction to the inverse problem. When sufficient regularization is applied, we demonstrate that the proposed method significantly improves the widely used approach using Green's functions. Motivated by real cell experiments, the equilibrium condition of a slowly migrating cell is imposed as a set of equality constraints on the unknown traction. Our validation benchmarks demonstrate that the numeric solution to the constrained inverse problem well recovers the actual traction when the optimal regularization parameter is used. The proposed method can thus be applied to study general force sensing problems, which utilize displacement measurements to sense inaccessible forces in linear elastic bodies with a priori constraints.

  1. Influences on lifetime of wire ropes in traction lifts

    NASA Astrophysics Data System (ADS)

    Vogel, W.

    2016-05-01

    Traction lifts are complex systems with rotating and translating moving masses, springs and dampers and several system inputs from the lifts and the users. The wire ropes are essential mechanical elements. The mechanical properties of the ropes in use depend on the rope construction, the load situation, nonlinearities and the lift dimensions. The mechanical properties are important for the proper use in lifts and the ride quality. But first of all the wire ropes (for all other suspension means as well) have to satisfy the safety relevant requirements sufficient lifetime, reliable determination of discard and sufficient and limited traction capacity. The lifetime of the wire ropes better the number of trips until rope discard depends on a lot of parameters of the rope and the rope application eg use of plastic deflection sheaves and reverse bending layouts. New challenges for rope lifetime are resulting from the more or less open D/d-ratio limits possible by certificates concerning the examination of conformity by notified bodies. This paper will highlight the basics of wire rope technology, the endurance and lifetime of wire ropes running over sheaves, and the different influences from the ropes and more and more important from the lift application parameters. Very often underestimated are the influences of transport, storage, installation and maintenance. With this background we will lead over to the calculation methods of wire rope lifetime considering the actual findings of wire rope endurance research. We'll show in this paper new and innovative facts as the influence of rope length and size factor in the lifetime formular, the reduction of lifetime caused by traction grooves, the new model for the calculation in reverse bending operations and the statistically firmed possibilities for machine roomless lifts (MRL) under very small bending conditions.

  2. Traction studies of northeast corridor rail passenger service: Executive summary

    NASA Technical Reports Server (NTRS)

    Macie, T. W.; Stallkamp, J. A.

    1980-01-01

    The enabling legislation of 1976 for improvement of service in the Northeast corridor (NEC) requires a schedule of 2 h 40 min between Washington and New York City by 1981 and 3 h 40 min between NYC and Boston, when the electrification is completed. Various options of the NEC operation that may satisfy the legislation were investigated, particularly in terms of travel time and energy consumption. NEC operations were compared with overseas systems and practices. The emerging new technology of AC traction was also evaluated.

  3. Analysis of DNA equilibrium configuration under interfacial traction.

    PubMed

    Wang, Y Z; Zhang, Q C; Wang, W; Yang, Y W

    2016-01-01

    Kirchhoff thin elastic rod models are important in the study of the mechanism determining the configurations of flexible structures not only at the macroscopic but also at the microscopic scale. In this study, the energy balance method has been well applied to analyze the configuration of a DNA elastic rod in the presence of interfacial traction. An approximate solution for the shape equations has been obtained, and the relationship between the interfacial factor and the configuration of the DNA segment is derived. The results may provide an explanation for the onset of the formation of kinks in DNA when immersed in a solution. PMID:27323042

  4. FreedomCAR Advanced Traction Drive Motor Development Phase I

    SciTech Connect

    Ley, Josh; Lutz, Jon

    2006-09-01

    The overall objective of this program is to design and develop an advanced traction motor that will meet the FreedomCAR and Vehicle Technologies (FCVT) 2010 goals and the traction motor technical targets. The motor specifications are given in Section 1.3. Other goals of the program include providing a cost study to ensure the motor can be developed within the cost targets needed for the automotive industry. The program has focused on using materials that are both high performance and low costs such that the performance can be met and cost targets are achieved. In addition, the motor technologies and machine design features must be compatible with high volume manufacturing and able to provide high reliability, efficiency, and ruggedness while simultaneously reducing weight and volume. Weight and volume reduction will become a major factor in reducing cost, material cost being the most significant part of manufacturing cost at high volume. Many motor technology categories have been considered in the past and present for traction drive applications, including: brushed direct current (DC), PM (PM) brushless dc (BLDC), alternating current (AC) induction, switched reluctance and synchronous reluctance machines. Of these machine technologies, PM BLDC has consistently demonstrated an advantage in terms of power density and efficiency. As rare earth magnet cost has declined, total cost may also be reduced over the other technologies. Of the many different configurations of PM BLDC machines, those which incorporate power production utilizing both magnetic torque as well as reluctance torque appear to have the most promise for traction applications. There are many different PM BLDC machine configurations which employ both of these torque producing mechanisms; however, most would fall into one of two categories--some use weaker magnets and rely more heavily on reluctance torque (reluctance-dominant PM machines), others use strong PMs and supplement with reluctance torque

  5. Interface traction stress of 3D dislocation loop in anisotropic bimaterial

    NASA Astrophysics Data System (ADS)

    Wu, Wenwang; Lv, Cunjing; Zhang, JinHuan

    2016-02-01

    By applying discrete Fast Fourier Transformation (FFT), semi-analytical solutions are developed to calculate the interface elastic fields of anisotropic bimaterial systems with perfect bonding, dislocation-like, force-like and linear spring-like interface models. Interface elastic fields are the linear superimposition of bulk stress, free surface relaxation image stress and interface traction stress (ITS) fields. Interface image energy of perfect bonding bimaterials can be solved through area integral over the interface plane, including the contribution of several componential stress fields. Calculation examples on dislocation loops within Cu-Nb bimaterial are performed to demonstrate the efficiency of such approaches. Effects of Ku = [kiju] for the dislocation-like, Kt = [kijt] for the force-like and Ks = diag [KT , KN ] for the linear spring-like imperfect interface models are investigated. Differences between perfect bonding and imperfect interface models, isotropic and anisotropic models are also studied. It is found that interface conditions and anisotropy have drastic effects on the interface elastic fields.

  6. 21 CFR 888.5850 - Nonpowered orthopedic traction apparatus and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nonpowered orthopedic traction apparatus and accessories. 888.5850 Section 888.5850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Surgical Devices § 888.5850 Nonpowered orthopedic traction apparatus and...

  7. Fuzzy logic electric vehicle regenerative antiskid braking and traction control system

    DOEpatents

    Cikanek, Susan R.

    1994-01-01

    An regenerative antiskid braking and traction control system using fuzzy logic for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensor and determining if regenerative antiskid braking control, requiring hydraulic braking control, and requiring traction control are required. The processor then employs fuzzy logic based on the determined vehicle state and provides command signals to a motor controller to control operation of the electric traction motor and to the brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative braking control, hydraulic braking control, and traction control.

  8. Fuzzy logic electric vehicle regenerative antiskid braking and traction control system

    DOEpatents

    Cikanek, S.R.

    1994-10-25

    An regenerative antiskid braking and traction control system using fuzzy logic for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensor and determining if regenerative antiskid braking control, requiring hydraulic braking control, and requiring traction control are required. The processor then employs fuzzy logic based on the determined vehicle state and provides command signals to a motor controller to control operation of the electric traction motor and to the brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative braking control, hydraulic braking control, and traction control. 123 figs.

  9. A modified method of traction for young children with congenital dislocation of the hip as a preliminary to reduction.

    PubMed

    Pan, K L; Rasit, H

    2004-12-01

    Many authors agree that preliminary traction prior to closed or open reduction for congenital dislocation of the hip is helpful. Different ways of traction have been used and each of them has its own advantages and disadvantages. One of the problems in the very young child is the difficulty in maintaining a suitable traction that is biomechanically effective. We found that using a rocker bed made the traction more "user friendly" for the child, the parent and the doctors. PMID:15941161

  10. Forces driving epithelial wound healing

    NASA Astrophysics Data System (ADS)

    Brugués, Agustí; Anon, Ester; Conte, Vito; Veldhuis, Jim H.; Gupta, Mukund; Colombelli, Julien; Muñoz, José J.; Brodland, G. Wayne; Ladoux, Benoit; Trepat, Xavier

    2014-09-01

    A fundamental feature of multicellular organisms is their ability to self-repair wounds through the movement of epithelial cells into the damaged area. This collective cellular movement is commonly attributed to a combination of cell crawling and `purse-string’ contraction of a supracellular actomyosin ring. Here we show by direct experimental measurement that these two mechanisms are insufficient to explain force patterns observed during wound closure. At early stages of the process, leading actin protrusions generate traction forces that point away from the wound, showing that wound closure is initially driven by cell crawling. At later stages, we observed unanticipated patterns of traction forces pointing towards the wound. Such patterns have strong force components that are both radial and tangential to the wound. We show that these force components arise from tensions transmitted by a heterogeneous actomyosin ring to the underlying substrate through focal adhesions. The structural and mechanical organization reported here provides cells with a mechanism to close the wound by cooperatively compressing the underlying substrate.

  11. Forces driving epithelial wound healing

    PubMed Central

    Veldhuis, Jim H.; Gupta, Mukund; Colombelli, Julien; Muñoz, José J.; Brodland, G. Wayne; Ladoux, Benoit; Trepat, Xavier

    2015-01-01

    A fundamental feature of multicellular organisms is their ability to self-repair wounds through the movement of epithelial cells into the damaged area. This collective cellular movement is commonly attributed to a combination of cell crawling and “purse-string” contraction of a supracellular actomyosin ring. Here we show by direct experimental measurement that these two mechanisms are insufficient to explain force patterns observed during wound closure. At early stages of the process, leading actin protrusions generate traction forces that point away from the wound, showing that wound closure is initially driven by cell crawling. At later stages, we observed unanticipated patterns of traction forces pointing towards the wound. Such patterns have strong force components that are both radial and tangential to the wound. We show that these force components arise from tensions transmitted by a heterogeneous actomyosin ring to the underlying substrate through focal adhesions. The structural and mechanical organization reported here provides cells with a mechanism to close the wound by cooperatively compressing the underlying substrate. PMID:27340423

  12. Treatment of traction-free boundary condition in three-dimensional dislocation dynamics using generalized image stress analysis

    SciTech Connect

    Khraishi, T A; Zbib, H M; Diaz de la Rubia, T

    2000-07-20

    Recent attention has been given to the proper treatment of the planar traction-free surfaces which typically bound a computational box in three-dimensional dislocation dynamics. This paper presents an alternative to the use of the finite-element method for this purpose. Here, to annul the tractions produced by a sub-surface dislocation segment on a finite-area free surface S, a combination of an image dislocation segment, and a distribution of N prismatic rectangular Volterra dislocation loops meshing S is utilized. The image dislocation segment, with the proper sign selection of the Burgers vector components, annuls the shear stresses, and the normal stress component is annulled discretely at N collocation points representing the centers of the loops. The unknowns in this problem are the magnitudes of the N Burgers vectors for the loops. Once these are determined, one can back calculate the Peach-Koehler force acting on the sub-surface segment and representing the effect of the free surface. As expected, the accuracy of the method improves as the loops continuously decrease in size.

  13. Application of 3-dimensional printing in hand surgery for production of a novel bone reduction clamp.

    PubMed

    Fuller, Sam M; Butz, Daniel R; Vevang, Curt B; Makhlouf, Mansour V

    2014-09-01

    Three-dimensional printing is being rapidly incorporated in the medical field to produce external prosthetics for improved cosmesis and fabricated molds to aid in presurgical planning. Biomedically engineered products from 3-dimensional printers are also utilized as implantable devices for knee arthroplasty, airway orthoses, and other surgical procedures. Although at first expensive and conceptually difficult to construct, 3-dimensional printing is now becoming more affordable and widely accessible. In hand surgery, like many other specialties, new or customized instruments would be desirable; however, the overall production cost restricts their development. We are presenting our step-by-step experience in creating a bone reduction clamp for finger fractures using 3-dimensional printing technology. Using free, downloadable software, a 3-dimensional model of a bone reduction clamp for hand fractures was created based on the senior author's (M.V.M.) specific design, previous experience, and preferences for fracture fixation. Once deemed satisfactory, the computer files were sent to a 3-dimensional printing company for the production of the prototypes. Multiple plastic prototypes were made and adjusted, affording a fast, low-cost working model of the proposed clamp. Once a workable design was obtained, a printing company produced the surgical clamp prototype directly from the 3-dimensional model represented in the computer files. This prototype was used in the operating room, meeting the expectations of the surgeon. Three-dimensional printing is affordable and offers the benefits of reducing production time and nurturing innovations in hand surgery. This article presents a step-by-step description of our design process using online software programs and 3-dimensional printing services. As medical technology advances, it is important that hand surgeons remain aware of available resources, are knowledgeable about how the process works, and are able to take advantage of

  14. Novel Transverse Flux Machine for Vehicle Traction Applications: Preprint

    SciTech Connect

    Wan, Z.; Ahmed, A.; Husain, I.; Muljadi, E.

    2015-04-02

    A novel transverse flux machine topology for electric vehicle traction applications using ferrite magnets is presented in this paper. The proposed transverse flux topology utilizes novel magnet arrangements in the rotor that are similar to the Halbach array to boost flux linkage; on the stator side, cores are alternately arranged around a pair of ring windings in each phase to make use of the entire rotor flux that eliminates end windings. Analytical design considerations and finite-element methods are used for an optimized design of a scooter in-wheel motor. Simulation results from finite element analysis (FEA) show that the motor achieved comparable torque density to conventional rare-earth permanent magnet (PM) machines. This machine is a viable candidate for direct-drive applications with low cost and high torque density.

  15. Scaling of Traction Stresses with Size of Cohesive Cell Colonies

    NASA Astrophysics Data System (ADS)

    Mertz, Aaron F.; Banerjee, Shiladitya; Che, Yonglu; Marchetti, M. Christina; Horsley, Valerie; Dufresne, Eric R.

    2012-02-01

    We explore the mechanical properties of colonies of cohesive cells adherent on soft substrates. Specifically, we image the spatial distribution of traction stresses exerted by colonies of primary mouse keratinocytes on fibronectin-coated silicone gels. These cells have strong cell-cell adhesions mediated by E-cadherin. We observe that the work performed by a colony on its substrate is concentrated at the colony's periphery. The total work is strongly correlated to the geometrical size of the colony but not to number of cells. In other words, the mechanical output of a large single cell mimics that of a cohesive colony with the same overall size. We compare our findings to a recent theoretical model that treats the cohesive colony as an active gel.

  16. Penile traction therapy for Peyronie's disease-what's the evidence?

    PubMed

    Usta, Mustafa Faruk; Ipekci, Tumay

    2016-06-01

    Penile traction therapy (PTT) is a new therapeutic option for men with Peyronie's disease (PD). However, it has a long history of use in other fields of medicine including bone, skin, skeletal muscle, and Dupuytren's. Mechanotransduction, or gradual expansion of tissue by traction, leads to the formation of new collagen tissue by cellular proliferation. As a molecular result, continuous extension of the fibrous plaque causes significant increases in collagenase and metalloproteinases, and, ultimately, to fibrous plaque softening and extension. This hypothetical knowledge has been supported by recent well designed experimental studies. Furthermore, several clinical papers have provided promising results on the use of PTT in PD patients. It has been shown in some series that the use of PTT significantly increases flaccid and stretched penile lengths and results in significant penile curvature improvement when compared to baseline. Furthermore, the use of PTT concomitantly with either verapamil or interferon α-2b has also been shown to be an effective therapy. Additionally, the beneficial effect of PTT on penile length before or after penile surgery in men with corporal fibrosis has been described. Finally, as a minimally invasive alternative treatment option to penile augmentation surgery in men with dysmorphophobia, PTT use has shown promising results by several experts. Studies have shown that PTT provides an acceptable, minimally invasive method that can produce effective and durable lengthening of the penis in men complaining of a small/short penis. There are, however, several criticisms related to the designs of the reported studies, such as small sample size and selection bias. Well-designed studies with larger numbers of patients and longer follow-up periods are, however, needed to establish the true benefits of PTT. PMID:27298777

  17. Pulse charging of lead-acid traction cells

    NASA Technical Reports Server (NTRS)

    Smithrick, J. J.

    1980-01-01

    Pulse charging, as a method of rapidly and efficiently charging 300 amp-hour lead-acid traction cells for an electric vehicle application was investigated. A wide range of charge pulse current square waveforms were investigated and the results were compared to constant current charging at the time averaged pulse current values. Representative pulse current waveforms were: (1) positive waveform-peak charge pulse current of 300 amperes (amps), discharge pulse-current of zero amps, and a duty cycle of about 50%; (2) Romanov waveform-peak charge pulse current of 300 amps, peak discharge pulse current of 15 amps, and a duty of 50%; and (3) McCulloch waveform peak charge pulse current of 193 amps, peak discharge pulse current of about 575 amps, and a duty cycle of 94%. Experimental results indicate that on the basis of amp-hour efficiency, pulse charging offered no significant advantage as a method of rapidly charging 300 amp-hour lead-acid traction cells when compared to constant current charging at the time average pulse current value. There were, however, some disadvantages of pulse charging in particular a decrease in charge amp-hour and energy efficiencies and an increase in cell electrolyte temperature. The constant current charge method resulted in the best energy efficiency with no significant sacrifice of charge time or amp-hour output. Whether or not pulse charging offers an advantage over constant current charging with regard to the cell charge/discharge cycle life is unknown at this time.

  18. Control of fracture reduction robot using force/torque measurement.

    PubMed

    Douke, T; Nakajima, Y; Mori, Y; Onogi, S; Sugita, N; Mitsuishi, M; Bessho, M; Ohhashi, S; Tobita, K; Ohnishi, I; Sakuma, I; Dohi, T; Maeda, Y; Koyama, T; Sugano, N; Yonenobu, K; Matsumoto, Y; Nakamura, K

    2008-01-01

    We have developed a surgical robotic system for femoral fracture reduction employing indirect traction. Indirect traction in fracture reduction is a generally used surgical method for preventing complications such as bone splits caused by high stress on bones. For traction, a patient's foot is gripped by a jig and pulled to the distal side. Indirect traction has the advantage of distributing bone stress by utilizing a strong traction force; however, this procedure does not accurately control the proper positioning of fractured fragments when a surgical robot is used. The human leg has knee and an ankle joints, and thus robotic motion presents problems in not being able to directly propagate reduction motion to a fractured femoral fragment, rendering control of bone position difficult. We propose a control method for fracture reduction robots using external force/torque measurements of the human leg to achieve precise fracture reduction. Results showed that the proposed method reduced repositioning error from 6.8 mm and 15.9 degrees to 0.7 mm and 5.3 degrees, respectively. PMID:19163404

  19. Analysis of electromyographic activities of the lumbar erector spinae caused by inversion traction

    PubMed Central

    Kim, Chung Yoo; Kang, Jong Ho

    2016-01-01

    [Purpose] The purpose of this study was to analyze changes in the electromyographic activities of the lumbar erector spinae caused by inversion traction in order to verify the relaxation effect. [Subjects and Methods] The subjects included 60 healthy male adults who were equally and randomly assigned to a 30–30° group, a 30–60° group, and a 60–60° group. Inversion traction was performed for six minutes, and the electromyographic activities of the lumbar erector spinae (L2, L4) were measured before and after inversion traction. [Results] The root mean square values at the L2 and L4 levels on both sides were statistically significantly higher after inversion traction compared with before inversion traction. Before inversion traction, the root mean square values at the L2 and L4 levels on both sides in the 30–60° group and 60–60° group were significantly higher than those in the 30–30° group, while the root mean square values at the L2 and L4 levels on both sides showed no significant differences between the groups before inversion traction. [Conclusion] The findings of this study indicated that IT is more likely to elicits an increase in muscle tension and prevent relaxation of the lumbar erector spinae. PMID:27190459

  20. Spatial and temporal traction response in human airway smooth muscle cells

    NASA Technical Reports Server (NTRS)

    Tolic-Norrelykke, Iva Marija; Butler, James P.; Chen, Jianxin; Wang, Ning

    2002-01-01

    Tractions that cells exert on their substrates are essential in cell spreading, migration, and contraction. These tractions can be determined by plating the cells on a flexible gel and measuring the deformation of the gel by using fluorescent beads embedded just below the surface of the gel. In this article we describe the image correlation method (ICM) optimized for determining the displacement field of the gel under a contracting cell. For the calculation of the traction field from the displacement field we use the recently developed method of Fourier transform traction cytometry (FTTC). The ICM and FTTC methods are applied to human airway smooth muscle cells during stimulation with the contractile agonist histamine or the relaxing agonist isoproterenol. The overall intensity of the cell contraction (the median traction magnitude, the energy transferred from the cell to the gel, and the net contractile moment) increased after activation with histamine, and decreased after treatment with isoproterenol. Cells exhibited regional differences in the time course of traction during the treatment. Both temporal evolution and magnitude of traction increase induced by histamine varied markedly among different cell protrusions, whereas the nuclear region showed the smallest response. These results suggest that intracellular mediators of cell adhesion and contraction respond to contractile stimuli with different rates and intensities in different regions of the cell.

  1. Giving a second thought to brisement force - a case report.

    PubMed

    Thakur, R; Shigli, A L; Thakur, G; Ahuja, R

    2015-01-01

    Fractures of temporomandibular joint (TMJ) may be caused by indirect trauma where force of trauma is transmitted to the mandibular condyle from a blow elsewhere or in other situations may also result from direct trauma. TMJ trauma in children is usually accompanied with pain, swelling, limited jaw movement and other additional findings. This report highlights a case of post traumatic trismus successfully managed with Brisement force - gradual tractional forces applied to the temporomandibular joint. PMID:25951309

  2. CLINICIAN PROFICIENCY IN DELIVERING MANUAL TREATMENT FOR NECK PAIN WITHIN SPECIFIED FORCE RANGES

    PubMed Central

    Gudavalli, Maruti Ram; Vining, Robert D.; Salsbury, Stacie A.; Corber, Lance; Long, Cynthia R.; Patwardhan, Avinash G.; Goertz, Christine M.

    2015-01-01

    Background Context Neck pain is a common musculoskeletal complaint responsive to manual therapies. Doctors of chiropractic commonly use manual cervical distraction, a mobilization procedure, to treat neck pain patients. However, it is unknown if clinicians can consistently apply standardized cervical traction forces, a critical step toward identifying an optimal therapeutic dose. Purpose The purpose of this study was to assess clinicians’ proficiency in delivering manually applied traction forces within specified ranges to neck pain patients. Study Design/Setting Observational study nested within a randomized clinical trial. Sample Two research clinicians provided study interventions to 48 participants with neck pain. Outcome Measures Clinician proficiency in delivering cervical traction forces within three specified ranges (low force <20 newtons (N); medium force 21–50N; and high force 51–100N). Methods This study was funded by a grant from the National Center for Complementary and Alternative Medicine, National Institutes of Health (Grant # 1 U19AT004663-01), and conducted in a facility funded by National Center for Research Resources, National Institutes of Health (Grant # C06 RR15433-01), and approved by an Institutional Review Board for the protection of human subjects. Senior author receives approximately $400–600 travel reimbursements per year for giving research presentations at certification seminars. The table manufacturer (Haven Innovations) sold the treatment table at a discounted price ($5000 discount) for research purposes. Participants were randomly allocated to three force-based treatment groups. Participants received five manual cervical distraction treatments over two weeks while lying prone on a treatment table instrumented with force sensors. Two clinicians delivered manual traction forces by treatment group. Clinicians treated participants first without real-time visual feedback displaying traction force and then with visual feedback

  3. The results of preoperative halo-gravity traction in children with severe spinal deformity.

    PubMed

    Garabekyan, Tigran; Hosseinzadeh, Pooya; Iwinski, Henry J; Muchow, Ryan D; Talwalkar, Vishwas R; Walker, Janet; Milbrandt, Todd A

    2014-01-01

    Halo-gravity traction has been used preoperatively for patients with severe spinal deformity but there are limited data in the literature on the results and complications. We studied the outcomes of perioperative halo-gravity traction in children with severe spinal deformity. A retrospective study was carried out on patients who were treated at our center. Twenty-one patients were included in the study. Radiographic and pulmonary function parameters showed significant improvement during the course of traction and at the final follow-up. The overall complication rate was 19%, including two patients with pin loosening and two patients with superficial pin-site infections treated with oral antibiotics. PMID:23942045

  4. Traction free finite elements with the assumed stress hybrid model. M.S. Thesis, 1981

    NASA Technical Reports Server (NTRS)

    Kafie, Kurosh

    1991-01-01

    An effective approach in the finite element analysis of the stress field at the traction free boundary of a solid continuum was studied. Conventional displacement and assumed stress finite elements were used in the determination of stress concentrations around circular and elliptical holes. Specialized hybrid elements were then developed to improve the satisfaction of prescribed traction boundary conditions. Results of the stress analysis indicated that finite elements which exactly satisfy the free stress boundary conditions are the most accurate and efficient in such problems. A general approach for hybrid finite elements which incorporate traction free boundaries of arbitrary geometry was formulated.

  5. The influence of surface dents and grooves on traction in sliding EHD point contacts

    NASA Technical Reports Server (NTRS)

    Cusano, C.; Wedeven, L. D.

    1983-01-01

    Changes in traction, caused by dents and grooves on a highly polished ball, are investigated as these defects approach and go through sliding elastohydrodynamic point contacts. The contacts are formed with the ball loading against a transparent disk. The ball and thus the topographical features are held stationary at various locations in the vicinity and within the contact while the disk is rotating. These topographical features can cause substantial changes in the traction when compared to traction obtained with smooth surfaces. Previously announced in STAR as N82-32734

  6. Gelled-electrolyte lead/acid batteries for stationary and traction applications

    NASA Astrophysics Data System (ADS)

    May, G. J.; Lenain, P.

    The development of new ranges of valve-regulated lead/acid (VRLA) batteries for stationary and traction applications is described. These batteries are gas recombining and use gelled electrolyte, tubular positive plates cast in lead-calcium-tin alloys and a specially-designed pressure relief valve. For stationary service, comparisons are made with VRLA batteries using absorptive glass mat separators. For traction applications, the relative merits of gel technology against alternative approaches to the achievement of lower maintenance for traction batteries are discussed. Operational experience with these batteries is outlined and guidelines indicated for correct application.

  7. Characterizing components of the Saw Palmetto Berry Extract (SPBE) on prostate cancer cell growth and traction

    SciTech Connect

    Scholtysek, Carina; Krukiewicz, Aleksandra A.; Alonso, Jose-Luis; Goldmann, Wolfgang H.

    2009-02-13

    Saw Palmetto Berry Extract (SPBE) is applied for prostate health and treatment of urinary tract infections, nonbacterial prostitis and Benign Prostatic Hyperplasia (BPH) in man. An assumption is that SPBE affects tumor cell progression and migration in breast and prostate tissue. In this work, DU-145 cells were used to demonstrate that SPBE and its sterol components, {beta}-sitosterol and stigmasterol, inhibit prostate cancer growth by increasing p53 protein expression and also inhibit carcinoma development by decreasing p21 and p27 protein expression. In the presence of cholesterol, these features are not only reversed but increased significantly. The results show for the first time the potential of SPBE, {beta}-sitosterol and stigmasterol as potential anti-tumor agents. Since the protein p53 is also regarded as nuclear matrix protein facilitating actin cytoskeletal binding, 2D tractions were measured. The cell adhesion strength in the presence of SPBE, {beta}-sitosterol and cholesterol and the observation was that the increase in p53 expression triggered an increase in the intracellular force generation. The results suggest a dual function of p53 in cells.

  8. 3-Dimensional Terraced NAND (3D TNAND) Flash Memory-Stacked Version of Folded NAND Array

    NASA Astrophysics Data System (ADS)

    Kim, Yoon; Cho, Seongjae; Lee, Gil Sung; Park, Il Han; Lee, Jong Duk; Shin, Hyungcheol; Park, Byung-Gook

    We propose a 3-dimensional terraced NAND flash memory. It has a vertical channel so it is possible to make a long enough channel in 1F2 size. And it has 3-dimensional structure whose channel is connected vertically along with two stairs. So we can obtain high density as in the stacked array structure, without silicon stacking process. We can make NAND flash memory with 3F2 cell size. Using SILVACO ATLAS simulation, we study terraced NAND flash memory characteristics such as program, erase, and read. Also, its fabrication method is proposed.

  9. Construction of 3-Dimensional Printed Ultrasound Phantoms With Wall-less Vessels.

    PubMed

    Nikitichev, Daniil I; Barburas, Anamaria; McPherson, Kirstie; Mari, Jean-Martial; West, Simeon J; Desjardins, Adrien E

    2016-06-01

    Ultrasound phantoms are invaluable as training tools for vascular access procedures. We developed ultrasound phantoms with wall-less vessels using 3-dimensional printed chambers. Agar was used as a soft tissue-mimicking material, and the wall-less vessels were created with rods that were retracted after the agar was set. The chambers had integrated luer connectors to allow for fluid injections with clinical syringes. Several variations on this design are presented, which include branched and stenotic vessels. The results show that 3-dimensional printing can be well suited to the construction of wall-less ultrasound phantoms, with designs that can be readily customized and shared electronically. PMID:27162278

  10. Dosimetric Comparison Between 3-Dimensional Conformal and Robotic SBRT Treatment Plans for Accelerated Partial Breast Radiotherapy.

    PubMed

    Goggin, L M; Descovich, M; McGuinness, C; Shiao, S; Pouliot, J; Park, C

    2016-06-01

    Accelerated partial breast irradiation is an attractive alternative to conventional whole breast radiotherapy for selected patients. Recently, CyberKnife has emerged as a possible alternative to conventional techniques for accelerated partial breast irradiation. In this retrospective study, we present a dosimetric comparison between 3-dimensional conformal radiotherapy plans and CyberKnife plans using circular (Iris) and multi-leaf collimators. Nine patients who had undergone breast-conserving surgery followed by whole breast radiation were included in this retrospective study. The CyberKnife planning target volume (PTV) was defined as the lumpectomy cavity + 10 mm + 2 mm with prescription dose of 30 Gy in 5 fractions. Two sets of 3-dimensional conformal radiotherapy plans were created, one used the same definitions as described for CyberKnife and the second used the RTOG-0413 definition of the PTV: lumpectomy cavity + 15 mm + 10 mm with prescription dose of 38.5 Gy in 10 fractions. Using both PTV definitions allowed us to compare the dose delivery capabilities of each technology and to evaluate the advantage of CyberKnife tracking. For the dosimetric comparison using the same PTV margins, CyberKnife and 3-dimensional plans resulted in similar tumor coverage and dose to critical structures, with the exception of the lung V5%, which was significantly smaller for 3-dimensional conformal radiotherapy, 6.2% when compared to 39.4% for CyberKnife-Iris and 17.9% for CyberKnife-multi-leaf collimator. When the inability of 3-dimensional conformal radiotherapy to track motion is considered, the result increased to 25.6%. Both CyberKnife-Iris and CyberKnife-multi-leaf collimator plans demonstrated significantly lower average ipsilateral breast V50% (25.5% and 24.2%, respectively) than 3-dimensional conformal radiotherapy (56.2%). The CyberKnife plans were more conformal but less homogeneous than the 3-dimensional conformal radiotherapy plans. Approximately 50% shorter