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Sample records for active tension development

  1. Investigations on the Incompletely Developed Plane Diagonal-Tension Field

    NASA Technical Reports Server (NTRS)

    Kuhn, Paul

    1940-01-01

    This report presents the results of an investigation on the incompletely developed diagonal-tension field. Actual diagonal-tension beams work in an intermediate stage between pure shear and pure diagonal tension; the theory developed by wagner for diagonal tension is not directly applicable. The first part of the paper reviews the most essential items of the theory of pure diagonal tension as well as previous attempts to formulate a theory of incomplete diagonal tension. The second part of the paper describes strain measurement made by the N. A. C. A. to obtain the necessary coefficients for the proposed theory. The third part of the paper discusses the stress analysis of diagonal-tension beams by means of the proposed theory.

  2. Development of Warp Yarn Tension During Shedding: A Theoretical Approach

    NASA Astrophysics Data System (ADS)

    Ghosh, Subrata; Chary, Prabhakara; Roy, Sukumar

    2015-10-01

    Theoretical investigation on the process of development of warp yarn tension during weaving for tappet shedding is carried out, based on the dynamic nature of shed geometry. The path of warp yarn on a weaving machine is divided into four different zones. The tension developed in each zone is estimated for every minute rotation of the bottom shaft. A model has been developed based on the dynamic nature of shed geometry and the possible yarn flow from one zone to another. A computer program, based on the model of shedding process, is developed for predicting the warp yarn tension variation during shedding. The output of the model and the experimental values of yarn tension developed in zone-D i.e. between the back rest and the back lease rod are compared, which shows a good agreement between them. The warp yarn tension values predicted by the model in zone-D are 10-13 % lesser than the experimentally measured values. By analyzing the theoretical data of the peak value of developed yarn tension at four zones i.e. zone-A, zone-B, zone-C and zone-D, it is observed that the peak yarn tension value of A, B, C-zones are much higher than the peak tension near the back rest i.e. at zone-D. It is about twice or more than the yarn tension near the back rest. The study also reveals that the developed yarn tension peak values are different for the extreme positions of a heald. The impact of coefficient of friction on peak value of yarn tension is nominal.

  3. Tension-type headache: pain, fatigue, tension, and EMG responses to mental activation.

    PubMed

    Bansevicius, D; Westgaard, R H; Sjaastad, O M

    1999-06-01

    Twenty patients with tension-type headache (14 chronic and 6 episodic) and 20 group-matched controls were selected for this study. They participated in a 1-hour, complex, two-choice, reaction-time test, as well as 5-minute pretest and 20-minute posttest periods. Subjects reported any pain in the forehead, temples, neck, and shoulders, as well as any feelings of fatigue and tension during the pretest, and every 10 minutes during the test and posttest by visual analog scales. Superficial electromyography was recorded simultaneously from positions representing the frontal and temporal muscles, neck (mostly splenius), and trapezius muscles. The location of pain corresponded to the position of the electrodes, but extended over a larger area. The test provoked pain in the forehead, neck, and shoulders of patients, i.e., pain scores from these regions increased significantly during the test. The pain scores continued to increase posttest. In patients, the EMG response of the trapezius (first 10 minutes of the test) was elevated relative to pretest. In controls, only the frontal muscles showed an EMG test response. Patients showed significantly higher EMG responses than controls in the neck (whole test period) and trapezius (first 10 minutes of the test period). There were significant differences in pain and fatigue scoring between patients and controls in all three periods and in tension scoring posttest. Fatigue correlated with pain, with increasing significance for all locations examined, while tension was mainly associated with the neck pain. The meaning of the variables "tension" and "fatigue" in headache, and their association with recorded muscle activity in various regions is discussed. The EMG response of the trapezius muscle to the test is discussed in comparison with similar responses observed in patients with other pain syndromes.

  4. Passive and active tension in single cardiac myofibrils.

    PubMed Central

    Linke, W A; Popov, V I; Pollack, G H

    1994-01-01

    Single myofibrils were isolated from chemically skinned rabbit heart and mounted in an apparatus described previously (Fearn et al., 1993; Linke et al., 1993). We measured the passive length-tension relation and active isometric force, both normalized to cross sectional area. Myofibrillar cross sectional area was calculated based on measurements of myofibril diameter from both phase-contrast images and electron micrographs. Passive tension values up to sarcomere lengths of approximately 2.2 microns were similar to those reported in larger cardiac muscle specimens. Thus, the element responsible for most, if not all, passive force of cardiac muscle at physiological sarcomere lengths appears to reside within the myofibrils. Above 2.2 microns, passive tension continued to rise, but not as steeply as reported in multicellular preparations. Apparently, structures other than the myofibrils become increasingly important in determining the magnitude of passive tension at these stretched lengths. Knowing the myofibrillar component of passive tension allowed us to infer the stress-strain relation of titin, the polypeptide thought to support passive force in the sarcomere. The elastic modulus of titin is 3.5 x 10(6) dyn cm-2, a value similar to that reported for elastin. Maximum active isometric tension in the single myofibril at sarcomere lengths of 2.1-2.3 microns was 145 +/- 35 mN/mm2 (mean +/- SD; n = 15). This value is comparable with that measured in fixed-end contractions of larger cardiac specimens, when the amount of nonmyofibrillar space in those preparations is considered. However, it is about 4 times lower than the maximum active tension previously measured in single skeletal myofibrils under similar conditions (Bartoo et al., 1993). Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 7 PMID:7948691

  5. The role of dynamic surface tension in cloud droplet activation

    NASA Astrophysics Data System (ADS)

    Petters, Markus D.; Suda, Sarah R.; Christensen, Sara I.

    2013-05-01

    We present new data on the cloud droplet forming abilities of two-component particles that contain the surfactant sodium dodecyl sulfate and sodium chloride or ammonium sulfate. The experiments were designed to test specific predictions made by Kohler theory that accounts for the reduction of surface tension and the partitioning of the surfactant between the interior and the surface of the droplet. We also introduced a pre-humidification step followed by a six minute time delay to test whether dynamic surface tension may lead to kinetic limitations on the partitioning process. Our results confirm previous studies that show that surfactants do not enhance cloud droplet activation relative to what would be predicted from water activity alone. The data obtained with and without time delay were indistinguishable within measurement uncertainty, suggesting that dynamic surface tension does not need to be considered in Kohler theory.

  6. Exploring Tensions in Developing Assessment for Learning

    ERIC Educational Resources Information Center

    Webb, Mary; Jones, Jane

    2009-01-01

    This paper is based on a study of classroom practice of primary school teachers who were engaged in a programme of professional development to implement formative assessment in their classrooms. The programme sought to develop the skills and expertise of teachers to enable formative assessment to be used to support and improve the learning of…

  7. Mechanisms underlying rhythmic locomotion: interactions between activation, tension and body curvature waves.

    PubMed

    Chen, Jun; Friesen, W Otto; Iwasaki, Tetsuya

    2012-01-15

    Undulatory animal locomotion arises from three closely related propagating waves that sweep rostrocaudally along the body: activation of segmental muscles by motoneurons (MNs), strain of the body wall, and muscle tension induced by activation and strain. Neuromechanical models that predict the relative propagation speeds of neural/muscle activation, muscle tension and body curvature can reveal crucial underlying control features of the central nervous system and the power-generating mechanisms of the muscle. We provide an analytical explanation of the relative speeds of these three waves based on a model of neuromuscular activation and a model of the body-fluid interactions for leech anguilliform-like swimming. First, we deduced the motoneuron spike frequencies that activate the muscle and the resulting muscle tension during swimming in intact leeches from muscle bending moments. Muscle bending moments were derived from our video-recorded kinematic motion data by our body-fluid interaction model. The phase relationships of neural activation and muscle tension in the strain cycle were then calculated. Our study predicts that the MN activation and body curvature waves have roughly the same speed (the ratio of curvature to MN activation speed ≈0.84), whereas the tension wave travels about twice as fast. The high speed of the tension wave resulting from slow MN activation is explained by the multiplicative effects of MN activation and muscle strain on tension development. That is, the product of two slower waves (activation and strain) with appropriate amplitude, bias and phase can generate a tension wave with twice the propagation speed of the factors. Our study predicts that (1) the bending moment required for swimming is achieved by minimal MN spike frequency, rather than by minimal muscle tension; (2) MN activity is greater in the mid-body than in the head and tail regions; (3) inhibitory MNs not only accelerate the muscle relaxation but also reduce the intrinsic

  8. Surface tension of liquid metals and alloys--recent developments.

    PubMed

    Egry, I; Ricci, E; Novakovic, R; Ozawa, S

    2010-09-15

    Surface tension measurements are a central task in the study of surfaces and interfaces. For liquid metals, they are complicated by the high temperatures and the consequently high reactivity characterising these melts. In particular, oxidation of the liquid surface in combination with evaporation phenomena requires a stringent control of the experimental conditions, and an appropriate theoretical treatment. Recently, much progress has been made on both sides. In addition to improving the conventional sessile drop technique, new containerless methods have been developed for surface tension measurements. This paper reviews the experimental progress made in the last few years, and the theoretical framework required for modelling and understanding the relevant physico-chemical surface phenomena.

  9. Communication: Activation energy of tension-induced pore formation in lipid membranes.

    PubMed

    Karal, Mohammad Abu Sayem; Yamazaki, Masahito

    2015-08-28

    Tension plays a vital role in pore formation in biomembranes, but the mechanism of pore formation remains unclear. We investigated the temperature dependence of the rate constant of constant tension (σ)-induced pore formation in giant unilamellar vesicles of lipid membranes using an experimental method we developed. By analyzing this result, we determined the activation energy (Ua) of tension-induced pore formation as a function of tension. A constant (U0) that does not depend on tension was found to contribute significantly to Ua. Analysis of the activation energy clearly indicated that the dependence of Ua on σ in the classical theory is correct, but that the classical theory of pore formation is not entirely correct due to the presence of U0. We can reasonably consider that U0 is a nucleation free energy to form a hydrophilic pre-pore from a hydrophobic pre-pore or a region with lower lateral lipid density. After obtaining U0, the evolution of a pre-pore follows a classical theory. Our data provide valuable information that help explain the mechanism of tension-induced pore formation in biomembranes and lipid membranes.

  10. Tensions in Beginning Teachers' Professional Identity Development, Accompanying Feelings and Coping Strategies

    ERIC Educational Resources Information Center

    Pillen, Marieke; Beijaard, Douwe; Brok, Perry den

    2013-01-01

    This study examined tensions encountered by 182 beginning teachers during their professional identity development, the feelings that accompanied these tensions and the ways they tried to cope with these. Professional identity tensions stem from an unbalanced personal and professional side of (becoming) a teacher. Tensions that are often mentioned…

  11. Regulation of tension development by MgADP and Pi without Ca2+. Role in spontaneous tension oscillation of skeletal muscle.

    PubMed Central

    Shimizu, H; Fujita, T; Ishiwata, S

    1992-01-01

    The length of sarcomeres in isolated myofibrils fixed at both ends spontaneously oscillates when MgADP and Pi coexist with MgATP in the absence of Ca2+ (Okamura, N., and S. Ishiwata, 1988. J. Muscle Res. Cell. Motil. 9:111-119). Here, we report that MgADP and Pi function as an activator and an inhibitor, respectively, of tension development of single skeletal muscle fibers in the absence of Ca2+ and the coexistence of MgADP and Pi with MgATP induces spontaneous tension oscillation. First, the isometric tension sharply increased when the concentration of MgADP became higher than approximately 3x that of MgATP and saturated at approximately 90% of the tension obtained under full Ca2+ activation; in parallel with this sigmoidal increase of tension, MgATPase activity appeared. The inhibition of contraction by the regulatory system seems to be desuppressed by the allosteric effect of actomyosin-ADP complex, similarly to so-called rigor complex. The ADP-induced tension was decreased along a reversed sigmoidal curve by the addition of Pi; actomyosin-ADP-Pi complex, which has no desuppression function, may be formed by exogenous Pi; accompanying the decline of tension, spontaneous oscillations of tension and sarcomere length appeared. It is suggested that the length oscillation of each (half) sarcomere would occur through the transition of cross-bridges between force-generating (on) and non-force-generating (off) states, which may be regulated by the mechanical states (strain) of cross-bridges and/or thin filaments. PMID:1600074

  12. Involvement of ROCK-mediated endothelial tension development in neutrophil-stimulated microvascular leakage

    PubMed Central

    Breslin, Jerome W.; Sun, Hengrui; Xu, Wenjuan; Rodarte, Charles; Moy, Alan B.; Wu, Mack H.; Yuan, Sarah Y.

    2009-01-01

    Neutrophil-induced coronary microvascular barrier dysfunction is an important pathophysiological event in heart disease. Currently, the precise cellular and molecular mechanisms of neutrophil-induced microvascular leakage are not clear. The aim of this study was to test the hypothesis that rho kinase (ROCK) increases coronary venular permeability in association with elevated endothelial tension. We assessed permeability to albumin (Pa) in isolated porcine coronary venules and in coronary venular endothelial cell (CVEC) monolayers. Endothelial barrier function was also evaluated by measuring transendothelial electrical resistance (TER) of CVEC monolayers. In parallel, we measured isometric tension of CVECs grown on collagen gels. Transference of constitutively active (ca)-ROCK protein into isolated coronary venules or CVEC monolayers caused a significant increase in Pa and decreased TER in CVECs. The ROCK inhibitor Y-27632 blocked the ca-ROCK-induced changes. C5a-activated neutrophils (106/ml) also significantly elevated venular Pa, which was dose-dependently inhibited by Y-27632 and a structurally distinct ROCK inhibitor, H-1152. In CVEC monolayers, activated neutrophils increased permeability with a concomitant elevation in isometric tension, both of which were inhibited by Y-27632 or H-1152. Treatment with ca-ROCK also significantly increased CVEC monolayer permeability and isometric tension, coupled with actin polymerization and elevated phosphorylation of myosin regulatory light chain on Thr18/Ser19. The data suggest that during neutrophil activation, ROCK promotes microvascular leakage in association with actin-myosin-mediated tension development in endothelial cells. PMID:16172166

  13. Between Product Development and Mass Production: Tensions as Triggers for Concept-Level Learning

    ERIC Educational Resources Information Center

    Jalonen, Meri; Ristimäki, Päivi; Toiviainen, Hanna; Pulkkis, Anneli; Lohtander, Mika

    2016-01-01

    Purpose: This paper aims to analyze learning in organizational transformations by focusing on concept-level tensions faced in two young companies, which were searching for a reorientation of activity with a production network between innovative product development and efficient mass production. Design/methodology/approach: An intervention-based…

  14. A transient outward current related to calcium release and development of tension in elephant seal atrial fibres.

    PubMed Central

    Maylie, J; Morad, M

    1984-01-01

    Membrane currents and development of tension in atrial trabeculae from elephant seal hearts were studied using a single sucrose-gap voltage-clamp technique. A transient outward current (Ito) was observed with kinetics, voltage and beat dependence, similar to those of tension. Ito had a bell-shaped voltage dependence similar to that of tension and the slow inward current (Isi). Ito, unlike Isi, showed beat dependence quite similar to developed tension. Increases in [Ca]o, frequency of stimulation, and addition of adrenaline enhanced Ito and developed tension. Ito was suppressed by addition of Mn2+, tetracaine, or by depolarizing pre-pulses (to -40 mV for 250 ms). Caffeine at low concentrations (1 mM) blocked beat dependence of Ito. At higher concentrations (greater than 5 mM) caffeine suppressed the activation of Ito, phasic tension, and the second component of the birefringence signal (related to Ca2+-releasing activity of the sarcoplasmic reticulum (s.r.]. Similar to Isi phasic tension and Ito, the voltage dependence of the second component of the birefringence signal was bell-shaped. Our studies suggest that activation of Ito is related to triggered release of Ca2+ from the s.r. which generates the phasic tension. An excitation-contraction coupling scheme is presented which incorporates these findings and suggests that Ito may be responsible for shorter action potentials found in atrial fibres. Images Plate 1 PMID:6512692

  15. Space Station Freedom Solar Array tension mechanism development

    NASA Technical Reports Server (NTRS)

    Allmon, Curtis; Haugen, Bert

    1994-01-01

    A tension mechanism is used to apply a tension force to the Space Station Freedom Solar Array Blanket. This tension is necessary to meet the deployed frequency requirement of the array as well as maintain the flatness of the flexible substrate solar cell blanket. The mechanism underwent a series of design iterations before arriving at the final design. This paper discusses the design and testing of the mechanism.

  16. Simulation by two calcium store models of myocardial dynamic properties: potentiation, staircase, and biphasic tension development.

    PubMed

    Wussling, M; Szymanski, G

    1986-04-01

    Most considerations and models concerning myocardial dynamic properties e.g. potentiation and staircase, are based upon the existence of storage structures in the heart muscle cell. The phenomenon of biphasic tension development (or two-component contraction) in heart muscle preparations of several mammalian species suggests that the sarcoplasmic reticulum is one, but by no means the major, source of activator calcium for the contractile system. The simulation of dynamic properties including biphasic tension development was performed in two steps by a simple "two-Ca store-model" and by an "expanded two-Ca store-model" with following results: Increasing potentiation indicated a decrease in the degree of coupling between the Ca stores. A shift of the interval strength curve to lower intervals as well as a decrease of the steady state contraction height implies a decrease of both, the coupling and the leakage time constant. There was no standard relation between staircase phenomena and structure parameters. Analog displays showed a late (or second) component at prolongated stimulation intervals, in the transient phase after a rest period, in the case of perfectly coupled or uncoupled stores, and at great time constant tau p (which characterizes the calcium pump activity). It is concluded that the late component of biphasic tension development is due to direct activation by the transsarcolemmal Ca flux of the myofilaments, whereas the early component is caused by the release of stored calcium. In the absence of an early component neither potentiation nor marked treppe may be expected.

  17. Tensions in Leadership Development: Head Teachers' Experience in North Cyprus

    ERIC Educational Resources Information Center

    Mertkan, Sefika

    2011-01-01

    Leadership development has been an area of much research, particularly in the last two decades. This has been mirrored by increased policy activity to build leadership capacity in schools through preparation programmes and continuing professional development. This article examines continuing professional development provision for head teachers in…

  18. Activation heat, activation metabolism and tension-related heat in frog semitendinosus muscles

    PubMed Central

    Homsher, E.; Mommaerts, W. F. H. M.; Ricchiuti, N. V.; Wallner, A.

    1972-01-01

    1. Frog semitendinosus muscles were stretched to various lengths beyond the rest length (l0) and their initial heat and isometric tension production were measured. 2. As the overlap between the thick and thin filaments is reduced, the initial twitch heat and tension decline in a linear manner. At a point at which the twitch tension approaches zero, the initial heat is 30% of that seen at l0. It is concluded that this heat is the activation heat and reflects the energetics of calcium release and reaccumulation. The initial heat at shorter sarcomere lengths appears to be the sum of the activation heat plus a heat production associated with the interaction of the thick and thin filaments. 3. A similar relationship between heat and tension production is seen in tetanic contractions. 4. The time course of activation heat production in a twitch can be resolved into two phases: a temperature insensitive (Q10 < 1·3) `fast' phase (with a time constant of 45 msec) and a temperature sensitive (Q10 = 2·8) `slow' phase (with a time constant of 330 msec at 0° C). 5. Measurements of the creatine phosphate (PC) hydrolysis by muscles contracting isometrically at various muscle lengths at and beyond l0, indicate an enthalpy change of -11·2 kcal/mole PC hydrolysed. The enthalpy change for the ATP hydrolysis by muscles stretched so that little or no tension was produced with stimulation was -9·9 kcal/mole ATP hydrolysed. It is concluded that the net activation heat is produced by the hydrolysis of PC or ATP. PMID:4536938

  19. Professional Development in Teaching and Learning for Early Career Academic Geographers: Contexts, Practices and Tensions

    ERIC Educational Resources Information Center

    Vajoczki, Susan; Biegas, Tamara C.; Crenshaw, Melody; Healey, Ruth L.; Osayomi, Tolulope; Bradford, Michael; Monk, Janice

    2011-01-01

    This paper provides a review of the practices and tensions informing approaches to professional development for early career academic geographers who are teaching in higher education. We offer examples from Britain, Canada, Nigeria and the USA. The tensions include: institutional and departmental cultures; models that offer generic and…

  20. Active transport of vesicles in neurons is modulated by mechanical tension

    NASA Astrophysics Data System (ADS)

    Ahmed, Wylie W.; Saif, Taher A.

    2014-03-01

    Effective intracellular transport of proteins and organelles is critical in cells, and is especially important for ensuring proper neuron functionality. In neurons, most proteins are synthesized in the cell body and must be transported through thin structures over long distances where normal diffusion is insufficient. Neurons transport subcellular cargo along axons and neurites through a stochastic interplay of active and passive transport. Mechanical tension is critical in maintaining proper function in neurons, but its role in transport is not well understood. To this end, we investigate the active and passive transport of vesicles in Aplysia neurons while changing neurite tension via applied strain, and quantify the resulting dynamics. We found that tension in neurons modulates active transport of vesicles by increasing the probability of active motion, effective diffusivity, and induces a retrograde bias. We show that mechanical tension modulates active transport processes in neurons and that external forces can couple to internal (subcellular) forces and change the overall transport dynamics.

  1. Development of a portable and fast wire tension measurement system for MWPC construction

    NASA Astrophysics Data System (ADS)

    Pan, Jing-Hui; Ma, Chang-Li; Gong, Xue-Yu; Sun, Zhi-Jia; Wang, Yan-Feng; Yin, Chen-Yan; Gong, Lei

    2016-09-01

    In a multi-wire proportional chamber detector (MWPC), the anode and signal wires must maintain suitable tension, which is very important for the detector’s stable and accurate performance. As a result, wire tension control and measurement is essential in MWPC construction. A high pressure 3He MWPC detector is to be used as the thermal neutron detector of the multi-functional reflectometer at China Spallation Neutron Source, and in the construction of the detector, we have developed a wire tension measurement system. This system is accurate, portable and time-saving. With it, the wire tension on an anode wire plane has been tested. The measurement results show that the wire tension control techniques used in detector manufacture are reliable. Supported by National Natural Science Foundation of China (A050506), State Key Laboratory of Particle Detection and Electronics and Key Laboratory of China Academy of Engineering Physics (Y490KF40HD)

  2. Changes in sarcomere length during isometric tension development in frog skeletal muscle.

    PubMed

    Cleworth, D R; Edman, K A

    1972-12-01

    1. Changes in sarcomere length during isometric contraction of isolated semitendinosus muscle fibres from the frog were studied using laser diffraction techniques. Movements of the first-order diffraction line relative to the zero-order reference were recorded from a screen on continuously moving film. Sarcomere length changes of 50 A could be resolved in this way.2. Following a latent period of approximately 12 msec after the stimulus of a single skeletal muscle fibre at 1-2 degrees C, there appeared to be a simultaneous onset of tension development and sarcomere shortening. Provided that the fibre was uniformly excited along its length, different regions shortened together by approximately the same amount. The extent of the shortening was a function of the total compliance of the tendons and tension measuring device.3. During the plateau of a smooth tetanus no fluctuations of first-order line width or zero- to first-order line spacing were detectable at any point examined along the preparation. This finding provides evidence that, in a functionally intact fibre, no synchronous oscillations of the sarcomeres, at least no length changes exceeding 50 A, occur during a fused tetanus. Furthermore, the fact that the first-order line did not increase in width as the preparation went from rest to full activity indicates that contraction proceeds without appreciable change in distribution of sarcomere lengths.4. The sarcomere movements during relaxation differed along the length of the fibre. As the tension declined smoothly, sarcomeres in some parts of the fibre underwent further shortening, while the end sarcomeres near the tendons and in one or two regions in the middle segment of the fibre were further extended. These data indicate that the duration of the mechanical activity differs in different regions along the length of the fibre. The pattern of relaxation, i.e. the behaviour of the sarcomeres in different fibre segments, is unique to any particular fibre.

  3. Development of a new methodology to study drop shape and surface tension in electric fields.

    PubMed

    Bateni, A; Susnar, S S; Amirfazli, A; Neumann, A W

    2004-08-31

    Development of a new methodology for the study of both shape and surface tension of conducting drops in an electric field is presented. This methodology, called axisymmetric drop shape analysis-electric fields (ADSA-EF), generates numerical drop profiles in an electrostatic field, for a given surface tension. Then, it calculates the true value of the surface tension by matching theoretical profiles to the shape of experimental drops, using the surface tension as an adjustable parameter. ADSA-EF can be employed to simulate and study drop shapes in the electric field and to determine its effect on liquid surface tension. The method can also be used to measure surface tension in microgravity, where current drop-shape techniques are not applicable. The axisymmetric shape of the drop is the only assumption made in the development of ADSA-EF. The new scheme is applicable when both gravity and electrostatic forces are present. Preliminary measurements using ADSA-EF suggest that the surface tension of water increases by about 2% when an electric field with the magnitude of 10(6) V/m is applied.

  4. Tension-related activity in the orbitofrontal cortex and amygdala: an fMRI study with music

    PubMed Central

    Lehne, Moritz; Rohrmeier, Martin

    2014-01-01

    Tonal music is characterized by a continuous flow of tension and resolution. This flow of tension and resolution is closely related to processes of expectancy and prediction and is a key mediator of music-evoked emotions. However, the neural correlates of subjectively experienced tension and resolution have not yet been investigated. We acquired continuous ratings of musical tension for four piano pieces. In a subsequent functional magnetic resonance imaging experiment, we identified blood oxygen level-dependent signal increases related to musical tension in the left lateral orbitofrontal cortex (pars orbitalis of the inferior frontal gyrus). In addition, a region of interest analysis in bilateral amygdala showed activation in the right superficial amygdala during periods of increasing tension (compared with decreasing tension). This is the first neuroimaging study investigating the time-varying changes of the emotional experience of musical tension, revealing brain activity in key areas of affective processing. PMID:23974947

  5. Tension-related activity in the orbitofrontal cortex and amygdala: an fMRI study with music.

    PubMed

    Lehne, Moritz; Rohrmeier, Martin; Koelsch, Stefan

    2014-10-01

    Tonal music is characterized by a continuous flow of tension and resolution. This flow of tension and resolution is closely related to processes of expectancy and prediction and is a key mediator of music-evoked emotions. However, the neural correlates of subjectively experienced tension and resolution have not yet been investigated. We acquired continuous ratings of musical tension for four piano pieces. In a subsequent functional magnetic resonance imaging experiment, we identified blood oxygen level-dependent signal increases related to musical tension in the left lateral orbitofrontal cortex (pars orbitalis of the inferior frontal gyrus). In addition, a region of interest analysis in bilateral amygdala showed activation in the right superficial amygdala during periods of increasing tension (compared with decreasing tension). This is the first neuroimaging study investigating the time-varying changes of the emotional experience of musical tension, revealing brain activity in key areas of affective processing.

  6. Effect of Kayak Ergometer Elastic Tension on Upper Limb EMG Activity and 3D Kinematics.

    PubMed

    Fleming, Neil; Donne, Bernard; Fletcher, David

    2012-01-01

    Despite the prevalence of shoulder injury in kayakers, limited published research examining associated upper limb kinematics and recruitment patterns exists. Altered muscle recruitment patterns on-ergometer vs. on-water kayaking were recently reported, however, mechanisms underlying changes remain to be elucidated. The current study assessed the effect of ergometer recoil tension on upper limb recruitment and kinematics during the kayak stroke. Male kayakers (n = 10) performed 4 by 1 min on-ergometer exercise bouts at 85%VO2max at varying elastic recoil tension; EMG, stroke force and three-dimensional 3D kinematic data were recorded. While stationary recoil forces significantly increased across investigated tensions (125% increase, p < 0.001), no significant differences were detected in assessed force variables during the stroke cycle. In contrast, increasing tension induced significantly higher Anterior Deltoid (AD) activity in the latter stages (70 to 90%) of the cycle (p < 0.05). No significant differences were observed across tension levels for Triceps Brachii or Latissimus Dorsi. Kinematic analysis revealed that overhead arm movements accounted for 39 ± 16% of the cycle. Elbow angle at stroke cycle onset was 144 ± 10°; maximal elbow angle (151 ± 7°) occurred at 78 ± 10% into the cycle. All kinematic markers moved to a more anterior position as tension increased. No significant change in wrist marker elevation was observed, while elbow and shoulder marker elevations significantly increased across tension levels (p < 0.05). In conclusion, data suggested that kayakers maintained normal upper limb kinematics via additional AD recruitment despite ergometer induced recoil forces. Key pointsKayak ergometer elastic tension significantly alters Anterior Deltoid recruitment patterns.Kayakers maintain optimal arm kinematics despite changing external forces via altered shoulder muscle recruitment.Overhead arm movements account for a high proportion of the kayak

  7. Effect of Kayak Ergometer Elastic Tension on Upper Limb EMG Activity and 3D Kinematics

    PubMed Central

    Fleming, Neil; Donne, Bernard; Fletcher, David

    2012-01-01

    Despite the prevalence of shoulder injury in kayakers, limited published research examining associated upper limb kinematics and recruitment patterns exists. Altered muscle recruitment patterns on-ergometer vs. on-water kayaking were recently reported, however, mechanisms underlying changes remain to be elucidated. The current study assessed the effect of ergometer recoil tension on upper limb recruitment and kinematics during the kayak stroke. Male kayakers (n = 10) performed 4 by 1 min on-ergometer exercise bouts at 85%VO2max at varying elastic recoil tension; EMG, stroke force and three-dimensional 3D kinematic data were recorded. While stationary recoil forces significantly increased across investigated tensions (125% increase, p < 0.001), no significant differences were detected in assessed force variables during the stroke cycle. In contrast, increasing tension induced significantly higher Anterior Deltoid (AD) activity in the latter stages (70 to 90%) of the cycle (p < 0.05). No significant differences were observed across tension levels for Triceps Brachii or Latissimus Dorsi. Kinematic analysis revealed that overhead arm movements accounted for 39 ± 16% of the cycle. Elbow angle at stroke cycle onset was 144 ± 10°; maximal elbow angle (151 ± 7°) occurred at 78 ± 10% into the cycle. All kinematic markers moved to a more anterior position as tension increased. No significant change in wrist marker elevation was observed, while elbow and shoulder marker elevations significantly increased across tension levels (p < 0.05). In conclusion, data suggested that kayakers maintained normal upper limb kinematics via additional AD recruitment despite ergometer induced recoil forces. Key pointsKayak ergometer elastic tension significantly alters Anterior Deltoid recruitment patterns.Kayakers maintain optimal arm kinematics despite changing external forces via altered shoulder muscle recruitment.Overhead arm movements account for a high proportion of the kayak

  8. Exploration of Tensions in a Mobile-Technology Supported Fieldtrip: An Activity Theory Perspective

    ERIC Educational Resources Information Center

    Lai, Chih-Hung; Chen, Fei-Ching; Yang, Jie-Chi

    2014-01-01

    The purpose of this study was to analyze how mobile technologies were incorporated and implemented in an outdoor learning activity. Two classes of primary school students participated in the experiment. Using activity theory as an analytical framework, it is found that underlying tensions provided rich insights into system dynamics and that…

  9. Understanding Tensions: Activity Systems Analysis of Cross-Continental Collaboration

    ERIC Educational Resources Information Center

    Ryder, LanHui Zhang; Yamagata-Lynch, Lisa

    2014-01-01

    Using the lens of Vygotsky's sociocultural theory, activity theory, and Engeström's activity systems analysis, this qualitative study explores students' experiences in the context of a sixteen-week transpacific collaboration between seven students at Northern Illinois University (NIU) and seven students from Shandong Normal University (SDNU),…

  10. Chinese Whispers - Algebra Style: Grammatical, Notational, Mathematical and Activity Tensions

    ERIC Educational Resources Information Center

    Hewitt, Dave

    2005-01-01

    This paper analyses students' written work from an activity based on two well known games in the UK: Chinese Whispers and Consequences. Within this activity students were asked to translate formal algebraic equations into word statements and vice versa. Using the framework of affordances and constraints to offer an account for what the students'…

  11. Effects of calcium entry blockers on tension development and calcium influx in rat uterus.

    PubMed Central

    Granger, S. E.; Hollingsworth, M.; Weston, A. H.

    1986-01-01

    Spontaneous and potassium chloride (KCl)-induced tension development of strips of whole uterus from the day-22 pregnant rat was reduced when the tissues were incubated in a calcium ion (Ca2+)-free medium. Strips of whole uterus, in an initially Ca2+-free medium, responded to the cumulative addition of Ca2+ with graded phasic tension development and associated rapid electrical discharges. The spasms were inhibited by gallopamil (100 nM) and diltiazem (1 microM). Strips of whole uterus in a depolarizing (40 mM K+) medium, which was initially Ca2+-free, responded to the cumulative addition of Ca2+ with graded tonic tension development without associated electrical discharges. These spasms were inhibited by calcium entry blockers with a rank order of potency of nifedipine = gallopamil greater than diltiazem greater than cinnarizine. KCl-induced tension development in endometrium-free uterine strips was antagonized by calcium entry blockers with a rank order of potency of nifedipine greater than gallopamil greater than diltiazem greater than cinnarizine. Ca2+ influx into endometrium-free uterine strips was assessed by means of the 'lanthanum method'. KCl induced a concentration-dependent increase in 45Ca2+ influx which was suppressed or abolished by nifedipine (2.5 nM), gallopamil (100 nM), diltiazem (500 nM) or cinnarizine (5 microM). It is concluded that spontaneous and KCl-induced tension development of rat uterus involves Ca2+ influx from the extracellular medium into the myometrial cell. These results support the hypothesis that nifedipine, gallopamil, diltiazem and cinnarizine inhibit Ca2+- and KCl-induced tension development of rat uterus by reduction of Ca2+ influx. PMID:3955298

  12. The assessment methods of laryngeal muscle activity in muscle tension dysphonia: a review.

    PubMed

    Khoddami, Seyyedeh Maryam; Nakhostin Ansari, Noureddin; Izadi, Farzad; Talebian Moghadam, Saeed

    2013-11-04

    The purpose of this paper is to review the methods used for the assessment of muscular tension dysphonia (MTD). The MTD is a functional voice disorder associated with abnormal laryngeal muscle activity. Various assessment methods are available in the literature to evaluate the laryngeal hyperfunction. The case history, laryngoscopy, and palpation are clinical methods for the assessment of patients with MTD. Radiography and surface electromyography (EMG) are objective methods to provide physiological information about MTD. Recent studies show that surface EMG can be an effective tool for assessing muscular tension in MTD.

  13. Cultural Tension and Career Development for Asian American College Students: A Phenomenological Study

    ERIC Educational Resources Information Center

    Lee, Eddie Kyo

    2013-01-01

    This mixed methods, phenomenological study examined how cultural tension influences career development for Asian American community college students. Students initially completed Phinney's (1992) Multigroup Ethnic Identity Measure (MEIM) and an instrument developed for this study called the Cultural Identification Survey. The mean for ethnic…

  14. Cross-Border Higher Education: Global and Local Tensions within Competition and Economic Development

    ERIC Educational Resources Information Center

    Owens, Taya L.; Lane, Jason E.

    2014-01-01

    In this chapter, the authors explore various types of cross-border higher education, considering equity and quality issues within these developments. With a particular focus on international branch campuses, the authors discuss the ways in which global competition for knowledge and economic development interact with tensions at the local level.

  15. Vocational Education and Training Teacher Professional Development: Tensions and Context

    ERIC Educational Resources Information Center

    Bound, Helen

    2011-01-01

    Planning and implementing teacher professional development is a process of engaging in organisational learning and change. Yet our planning and implementation of professional development is at times a series of one-off sessions and can be quite ad hoc. This paper argues that teacher learning takes place not only through formal sessions but also…

  16. Active tension adaptation at a shortened arterial muscle length: inhibition by cytochalasin-D.

    PubMed

    Bednarek, Melissa L; Speich, John E; Miner, Amy S; Ratz, Paul H

    2011-04-01

    Unlike the static length-tension curve of striated muscle, airway and urinary bladder smooth muscles display a dynamic length-tension curve. Much less is known about the plasticity of the length-tension curve of vascular smooth muscle. The present study demonstrates that there were significant increases of ∼15% in the phasic phase and ∼10% in the tonic phase of a third KCl-induced contraction of a rabbit femoral artery ring relative to the first contraction after a 20% decrease in length from an optimal muscle length (L(0)) to 0.8-fold L(0). Typically, three repeated contractions were necessary for full length adaptation to occur. The tonic phase of a third KCl-induced contraction was increased by ∼50% after the release of tissues from 1.25-fold to 0.75-fold L(o). The mechanism for this phenomenon did not appear to lie in thick filament regulation because there was no increase in myosin light chain (MLC) phosphorylation to support the increase in tension nor was length adaptation abolished when Ca(2+) entry was limited by nifedipine and when Rho kinase (ROCK) was blocked by H-1152. However, length adaptation of both the phasic and tonic phases was abolished when actin polymerization was inhibited through blockade of the plus end of actin by cytochalasin-D. Interestingly, inhibition of actin polymerization when G-actin monomers were sequestered by latrunculin-B increased the phasic phase and had no effect on the tonic phase of contraction during length adaptation. These data suggest that for a given level of cytosolic free Ca(2+), active tension in the femoral artery can be sensitized not only by regulation of MLC phosphatase via ROCK and protein kinase C, as has been reported by others, but also by a nonmyosin regulatory mechanism involving actin polymerization. Dysregulation of this form of active tension modulation may provide insight into alterations of large artery stiffness in hypertension.

  17. Ca(2+)-induced tension development in the stalks of glycerinated Vorticella convallaria.

    PubMed

    Moriyama, Y; Yasuda, K; Ishiwata, S; Asai, H

    1996-01-01

    We have developed a method of measuring the isometric tension in glycerinated stalks of Vorticella convallaria. Using this method, we measured tension vs. pCa relations in glycerinated V. convallaria stalks. The maximum isometric tension was 4 x 10(-8) N on average. The Hill's parameter, n, which is the number of calcium ions bound simultaneously and cooperatively to a contractile element (a force generating element), is approximately 3.2 when the Ca2+ concentration is increased and 2.5 when it is decreased. In order to estimate the efficiency of the energy conversion of Ca2+ binding to mechanical work, we measured the Ca(2+)-induced Carnot cycle in the Vorticella stalk. The energy efficiency was tentatively estimated to be about 7%. With this method, we have also succeeded in measuring the isometric tension of isolated spasmoneme, the rubber-like contractile fibrous organelle in the stalk. The maximum tension of spasmoneme was approximately one tenth that of the glycerinated stalk. We speculate that the isolated spasmoneme was only partially functional due to damage sustained when it was pulled out of the stalk.

  18. Gibberellin mediates the development of gelatinous fibres in the tension wood of inclined Acacia mangium seedlings

    PubMed Central

    Nugroho, Widyanto Dwi; Nakaba, Satoshi; Yamagishi, Yusuke; Begum, Shahanara; Marsoem, Sri Nugroho; Ko, Jae-Heung; Jin, Hyun-O; Funada, Ryo

    2013-01-01

    Background and Aims Gibberellin stimulates negative gravitropism and the formation of tension wood in tilted Acacia mangium seedlings, while inhibitors of gibberellin synthesis strongly inhibit the return to vertical growth and suppress the formation of tension wood. To characterize the role of gibberellin in tension wood formation and gravitropism, this study investigated the role of gibberellin in the development of gelatinous fibres and in the changes in anatomical characteristics of woody elements in Acacia mangium seedlings exposed to a gravitational stimulus. Methods Gibberellin, paclobutrazol and uniconazole-P were applied to the soil in which seedlings were growing, using distilled water as the control. Three days after the start of treatment, seedlings were inclined at 45 ° to the vertical and samples were harvested 2 months later. The effects of the treatments on wood fibres, vessel elements and ray parenchyma cells were analysed in tension wood in the upper part of inclined stems and in the opposite wood on the lower side of inclined stems. Key Results Application of paclobutrazol or uniconazole-P inhibited the increase in the thickness of gelatinous layers and prevented the elongation of gelatinous fibres in the tension wood of inclined stems. By contrast, gibberellin stimulated the elongation of these fibres. Application of gibberellin and inhibitors of gibberellin biosynthesis had only minor effects on the anatomical characteristics of vessel and ray parenchyma cells. Conclusions The results suggest that gibberellin is important for the development of gelatinous fibres in the tension wood of A. mangium seedlings and therefore in gravitropism. PMID:24043495

  19. Environmental Education in Three German-Speaking Countries: Tensions and Challenges for Research and Development

    ERIC Educational Resources Information Center

    Nikel, Jutta; Reid, Alan

    2006-01-01

    In this article, we explore a series of issues and tensions raised by the papers in this Special Issue of "Environmental Education Research." This papers focus on developments in environmental education and ESD research in Germany, Austria and Switzerland. In order to provide an alternative framework for contextualising and understanding…

  20. Biofeedback for Developing Self-Control of Tension and Stress in One's Hierarchy of Psychological States.

    ERIC Educational Resources Information Center

    Cassel, Russell

    1985-01-01

    Describes six stage hierarchial patterns in the development of self-control through biofeedback. The stages include Skeletal and Striated Muscle Tension; Visceral Involvement-Anxiety Neuroses; Chronic Physiological Dysfunctioning; Decision Making Competency; Twilight Learning-Permissive Concentration; and Autogenic Feedback Training. (BL)

  1. Jujuboside B Reduces Vascular Tension by Increasing Ca2+ Influx and Activating Endothelial Nitric Oxide Synthase

    PubMed Central

    Zhao, Yixiu; Zhang, Xin; Li, Jiannan; Bian, Yu; Sheng, Miaomiao; Liu, Bin; Fu, Zidong; Zhang, Yan; Yang, Baofeng

    2016-01-01

    Jujuboside B has been reported to have protective effect on many cardiovascular diseases. However, the effects of Jujuboside B on vascular tension and endothelial function are unknown. The present study investigated the effects of Jujuboside B on reducing vascular tension, protecting endothelial function and the potential mechanisms. The tension of isolated rat thoracic aorta ring was measured by Wire myograph system. The concentration of nitric oxide (NO) and the activity of endothelial nitric oxide synthase (eNOS) in human aortic endothelial cells (HAECs) were determined by Griess reagent method and enzyme-linked immune sorbent assay. The protein levels of eNOS and p-eNOS at Serine-1177 were determined by western blot analysis. Intracellular Ca2+ concentration in HAECs was measured by laser confocal imaging microscopy. Results showed that Jujuboside B reduced the tension of rat thoracic aorta rings with intact endothelium in a dose-dependent manner. L-NAME, KN93, EGTA, SKF96365, iberiotoxin and glibenclamide significantly attenuated Jujuboside B-induced vasodilation in endothelium-intact tissues. In contrast, indometacin and 4-DAMP had no such effects. Jujuboside B also promoted NO generation and increased eNOS activity, which were attenuated by L-NAME, EGTA and SKF96365. Moreover, Jujuboside B increased intracellular Ca2+ concentration dose-dependently, which was inhibited by EGTA and SKF96365. Besides, Jujuboside B induced a rapid Ca2+ influx instantaneously after depleting intracellular Ca2+ store, which was significantly inhibited by SKF96365. In conclusion, this study preliminarily confirmed that Jujuboside B reduced vascular tension endothelium-dependently. The underlying mechanisms involved that Jujuboside B increased extracellular Ca2+ influx through endothelial transient receptor potential cation (TRPC) channels, phosphorylated eNOS and promoted NO generation in vascular endothelial cells. In addition, Jujuboside B-induced vasodilation involved

  2. Jujuboside B Reduces Vascular Tension by Increasing Ca2+ Influx and Activating Endothelial Nitric Oxide Synthase.

    PubMed

    Zhao, Yixiu; Zhang, Xin; Li, Jiannan; Bian, Yu; Sheng, Miaomiao; Liu, Bin; Fu, Zidong; Zhang, Yan; Yang, Baofeng

    2016-01-01

    Jujuboside B has been reported to have protective effect on many cardiovascular diseases. However, the effects of Jujuboside B on vascular tension and endothelial function are unknown. The present study investigated the effects of Jujuboside B on reducing vascular tension, protecting endothelial function and the potential mechanisms. The tension of isolated rat thoracic aorta ring was measured by Wire myograph system. The concentration of nitric oxide (NO) and the activity of endothelial nitric oxide synthase (eNOS) in human aortic endothelial cells (HAECs) were determined by Griess reagent method and enzyme-linked immune sorbent assay. The protein levels of eNOS and p-eNOS at Serine-1177 were determined by western blot analysis. Intracellular Ca2+ concentration in HAECs was measured by laser confocal imaging microscopy. Results showed that Jujuboside B reduced the tension of rat thoracic aorta rings with intact endothelium in a dose-dependent manner. L-NAME, KN93, EGTA, SKF96365, iberiotoxin and glibenclamide significantly attenuated Jujuboside B-induced vasodilation in endothelium-intact tissues. In contrast, indometacin and 4-DAMP had no such effects. Jujuboside B also promoted NO generation and increased eNOS activity, which were attenuated by L-NAME, EGTA and SKF96365. Moreover, Jujuboside B increased intracellular Ca2+ concentration dose-dependently, which was inhibited by EGTA and SKF96365. Besides, Jujuboside B induced a rapid Ca2+ influx instantaneously after depleting intracellular Ca2+ store, which was significantly inhibited by SKF96365. In conclusion, this study preliminarily confirmed that Jujuboside B reduced vascular tension endothelium-dependently. The underlying mechanisms involved that Jujuboside B increased extracellular Ca2+ influx through endothelial transient receptor potential cation (TRPC) channels, phosphorylated eNOS and promoted NO generation in vascular endothelial cells. In addition, Jujuboside B-induced vasodilation involved

  3. Tension headache

    MedlinePlus

    ... headache; Muscle contraction headache; Headache - benign; Headache - tension; Chronic headaches - tension; Rebound headaches - tension ... headaches can occur when you also have a migraine. Tension headaches are not associated with brain diseases.

  4. Calcium-Activated Tension of Skinned Muscle Fibers of the Frog

    PubMed Central

    Godt, Robert E.

    1974-01-01

    The influence of MgATP on the Ga++-activated isometric tension of skinned frog muscle fibers was examined in solutions containing: Mg++ = 5 mM, creatine phosphate (CP) = 14.5 mM, creatinephosphokinase (CPK) = 1 mg/ml, total EGTA = 7 mM, CaCl2, KCl, imidazole ≥ 20 mM so that ionic strength = 0.15, pH = 7.00, and MgATP = 2 mM, 0.1 mM, or 20 µM. CP and CPK were necessary for these experiments as determined experimentally by their effect on the tension-Ca++ relation, which was saturated for CP ≥ 14.5 mM. This was interpreted to mean that sufficient CP was present to effectively buffer MgATP intracellularly. Decreasing MgATP shifts the tension-pCa curve to higher pCa (-log Ca++) so that, for half-maximal tension: pCa1/2 = 4.5 for MgATP = 2 mM, pCa1/2 = 5.1 for MgATP = 0.1 mM, and pCa1/2 = 5.8 for MgATP = 20 µM; maximum isometric tension is the same in all cases, however. If MgATP was decreased to 1 µM, tension at Ga++ > 10–8 M was 84% of the maximum Ca-+-activated tension in 2 mM MgATP and increased only slightly to 90% for pCa = 4.5. Weber (1970, In The Physiology and Biochemistry of Muscle as Food, Volume 2, E. J. Briskey, R. G. Cassens, and B. B. Marsh, University of Wisconsin Press, Madison, Wis.), using similar solutions, observed similar shifts in half-maximal calcium activation of rabbit myofibril ATPase rates. In explanation, Weber and Bremel (1971, In Contractility of Muscle Cells and Related Processes, R. J. Podolsky, editor, Prentice-Hall, Inc., Englewood Cliffs, N.J.; Bremel and Weber, 1972, Nat. New Biol., 238:97) have described a mechanism whereby, at low ATP, "rigor complexes" are formed between myosin and thin filament actin and, in turn, alter the calcium affinity of one class of the two Ca++-binding sites on troponin, so that the thin filament is "turned on" for contraction at lower Ca++ levels. Tension data from skinned fibers substantially supports this hypothesis. A stability constant for CaEGTA of 2.62 x 1010 M–1 was determined, with the

  5. Development of a space qualified Surface Tension Confined Liquid Cryogen Cooler (STCLCC)

    NASA Technical Reports Server (NTRS)

    Castles, Stephen H.; Schein, Michael E.

    1988-01-01

    The Surface Tension Confined Liquid Cryogen Cooler (STCLCC), a new type of cryogenic cooler which is being developed by the NASA-GSFC for spaceflight payloads, is described. The STCLCC will be capable of maintaining instrumentation within the temperature range of 10-120 K and will allow liquid cryogens to be flown in space without the risk of liquid being entrained in the vent gas. A low-density open-cell material in the STCLCC acts as a 'sponge', with the surface tension trapping the liquid cryogen within its pores and keeping the liquid away from the cooler's vent during launch, zero-g operations, and landing. It is emphasized that the STCLCC concept is amenable to a wide variety of applications, whenever a passive low-cost cooler is required or when the on-orbit service of a cooler would increase a mission's lifetime.

  6. Dynamic calcium requirements for activation of rabbit papillary muscle calculated from tension-independent heat.

    PubMed

    Blanchard, E M; Mulieri, L A; Alpert, N R

    1990-04-03

    The heat generated by right ventricular papillary muscles of rabbits was measured after adenosine triphosphate (ATP) splitting by the contractile proteins was chemically inhibited. This tension-independent heat (TIH) (1 mJ/g wet weight) was used to calculate the total calcium (Ca) cycled in a muscle twitch by assuming that 87% of TIH was due to Ca2+ transport by the sarcoplasmic reticulum with a coupling ratio of 2 Ca2+/ATP split; the enthalpy of creatine phosphate hydrolysis buffering ATP was taken as -34 KJ/mol. The estimated Ca turnover per muscle twitch at 21 degrees C, 0.2 Hz pacing rate, and 2.5 mM Ca in the Krebs solution was approximately equal to 50 nmol/g wet weight. There was a tight positive correlation between TIH and mechanical activation during steady-state measurements but no correlation during the sharp increase in mechanical activation (treppe) when stimulation was resumed after a rest period. It is suggested that while total Ca cycling remains unchanged during the initial period of tension treppe, the free Ca2+ transient and mechanical activation increase sharply due to resaturation of high affinity Ca2+ buffers, other than troponin C, depleted of Ca2+ during the rest period.

  7. The activation mode of the mechanosensitive ion channel, MscL, by lysophosphatidylcholine differs from tension-induced gating

    PubMed Central

    Mukherjee, Nobina; Jose, Mac Donald; Birkner, Jan Peter; Walko, Martin; Ingólfsson, Helgi I.; Dimitrova, Anna; Arnarez, Clément; Marrink, Siewert J.; Koçer, Armağan

    2014-01-01

    One of the best-studied mechanosensitive channels is the mechanosensitive channel of large conductance (MscL). MscL senses tension in the membrane evoked by an osmotic down shock and directly couples it to large conformational changes leading to the opening of the channel. Spectroscopic techniques offer unique possibilities to monitor these conformational changes if it were possible to generate tension in the lipid bilayer, the native environment of MscL, during the measurements. To this end, asymmetric insertion of l-α-lysophosphatidylcholine (LPC) into the lipid bilayer has been effective; however, how LPC activates MscL is not fully understood. Here, the effects of LPC on tension-sensitive mutants of a bacterial MscL and on MscL homologs with different tension sensitivities are reported, leading to the conclusion that the mode of action of LPC is different from that of applied tension. Our results imply that LPC shifts the free energy of gating by interfering with MscL-membrane coupling. Furthermore, we demonstrate that the fine-tuned addition of LPC can be used for controlled activation of MscL in spectroscopic studies.—Mukherjee, N., Jose, M. D., Birkner, J. P., Walko, M., Ingólfsson, H. I., Dimitrova, A., Arnarez, C., Marrink, S. J., Koçer, A. The activation mode of the mechanosensitive ion channel, MscL, by lysophosphatidylcholine differs from tension-induced gating. PMID:24958207

  8. Low Oxygen Tension Enhances Expression of Myogenic Genes When Human Myoblasts Are Activated from G0 Arrest

    PubMed Central

    Sellathurai, Jeeva; Nielsen, Joachim; Hejbøl, Eva Kildall; Jørgensen, Louise Helskov; Dhawan, Jyotsna; Nielsen, Michael Friberg Bruun; Schrøder, Henrik Daa

    2016-01-01

    Objectives Most cell culture studies have been performed at atmospheric oxygen tension of 21%, however the physiological oxygen tension is much lower and is a factor that may affect skeletal muscle myoblasts. In this study we have compared activation of G0 arrested myoblasts in 21% O2 and in 1% O2 in order to see how oxygen tension affects activation and proliferation of human myoblasts. Materials and Methods Human myoblasts were isolated from skeletal muscle tissue and G0 arrested in vitro followed by reactivation at 21% O2 and 1% O2. The effect was assesses by Real-time RT-PCR, immunocytochemistry and western blot. Results and Conclusions We found an increase in proliferation rate of myoblasts when activated at a low oxygen tension (1% O2) compared to 21% O2. In addition, the gene expression studies showed up regulation of the myogenesis related genes PAX3, PAX7, MYOD, MYOG (myogenin), MET, NCAM, DES (desmin), MEF2A, MEF2C and CDH15 (M-cadherin), however, the fraction of DES and MYOD positive cells was not increased by low oxygen tension, indicating that 1% O2 may not have a functional effect on the myogenic response. Furthermore, the expression of genes involved in the TGFβ, Notch and Wnt signaling pathways were also up regulated in low oxygen tension. The differences in gene expression were most pronounced at day one after activation from G0-arrest, thus the initial activation of myoblasts seemed most sensitive to changes in oxygen tension. Protein expression of HES1 and β-catenin indicated that notch signaling may be induced in 21% O2, while the canonical Wnt signaling may be induced in 1% O2 during activation and proliferation of myoblasts. PMID:27442119

  9. Activated drying in hydrophobic nanopores and the line tension of water

    PubMed Central

    Guillemot, Ludivine; Biben, Thierry; Galarneau, Anne; Vigier, Gérard; Charlaix, Élisabeth

    2012-01-01

    We study the slow dynamics of water evaporation out of hydrophobic cavities by using model porous silica materials grafted with octylsilanes. The cylindrical pores are monodisperse, with a radius in the range of 1–2 nm. Liquid water penetrates in the nanopores at high pressure and empties the pores when the pressure is lowered. The drying pressure exhibits a logarithmic growth as a function of the driving rate over more than three decades, showing the thermally activated nucleation of vapor bubbles. We find that the slow dynamics and the critical volume of the vapor nucleus are quantitatively described by the classical theory of capillarity without adjustable parameter. However, classical capillarity utterly overestimates the critical bubble energy. We discuss the possible influence of surface heterogeneities, long-range interactions, and high-curvature effects, and we show that a classical theory can describe vapor nucleation provided that a negative line tension is taken into account. The drying pressure then provides a determination of this line tension with much higher precision than currently available methods. We find consistent values of the order of −30 pN in a variety of hydrophobic materials. PMID:23144219

  10. Using magnets and magnetic beads to dissect signaling pathways activated by mechanical tension applied to cells.

    PubMed

    Marjoram, R J; Guilluy, C; Burridge, K

    2016-02-01

    Cellular tension has implications in normal biology and pathology. Membrane adhesion receptors serve as conduits for mechanotransduction that lead to cellular responses. Ligand-conjugated magnetic beads are a useful tool in the study of how cells sense and respond to tension. Here we detail methods for their use in applying tension to cells and strategies for analyzing the results. We demonstrate the methods by analyzing mechanotransduction through VE-cadherin on endothelial cells using both permanent magnets and magnetic tweezers.

  11. Development of bilateral tension pneumothorax under anesthesia in a Boerhaave's syndrome patient: a case report

    PubMed Central

    Oh, Mi Kyung; Jeon, Woo Jae; Kwon, Yong Deok; Kim, Kyoung Hun

    2016-01-01

    A 33-year-old male visited the emergency room with abdominal pain which developed after a vomiting episode. Based on the pneumomediastinum findings from a chest radiograph and a contrast-enhanced chest and abdominal computed tomography scan, the patient was diagnosed with Boerhaave's syndrome. Preoperative radiologic findings showed no pneumothorax or pleural effusion. Once anesthesia was administered, the patient developed near complete cardiopulmonary collapse due to a bilateral tension pneumothorax, which was treated by bilateral thoracentesis, followed by chest tube insertion. Despite a left side rupture, the damaged right lung was unable to overcome single right ventilation, so the surgery was completed via right thoracotomy. The ruptured site was treated, and the patient was transferred to the intensive care unit. We discuss the anesthetic implications of this disease and how to prevent fatal complications. PMID:27066209

  12. Contractility studies on isolated bovine choroidal small arteries: determination of the active and passive wall tension-internal circumference relation.

    PubMed

    Delaey, C; Boussery, K; Van de Voorde, J

    2002-09-01

    Studies on isolated choroidal arteries could help to understand the regulatory mechanisms in the choroidal circulation. The aim of the present study was therefore to assess whether contractility studies on isolated choroidal arteries were feasible and to determine the active and passive wall tension-internal circumference relation of these arteries. This relation is essential for reliable further pharmacodynamic studies on these vessels. Isolated choroidal arteries were mounted on a wire myograph for isometric tension recording. After the vessel was mounted, the L(100) (the circumference of the vessel at a transmural pressure of 100 mmHg) was determined. Then the passive and active wall tension-internal circumference relation of the choroidal vessels was obtained by stepwise increasing the internal circumference. The changes in the internal circumference were expressed as a percentage of L(100). After each increase in circumference, the passive tone (in a calcium free medium), the spontaneous tone (in a Krebs--Ringer bicarbonate solution) and the active tone (in a solution containing K(+) 120 mM and prostaglandin F(2 alpha) 30 microM) was measured. The passive tone of the vessel increased exponentially with the circumference of the vessel. Both the spontaneous tone and the active tone also increased when the vessel was stretched. They peaked when the internal circumference approached 90% of the L(100) and diminished again when the circumference was further increased. The peak value of the active tension curve averaged 2.24+/-0.47 Nm(-1) (n=10). The passive tension was 0.57+/-0.08 Nm(-1) (n=10) at this circumference. The peak value of the spontaneous tension curve averaged 0.37+/-0.08 Nm(-1) (n=10). It can be concluded that in vitro contractility studies on isolated choroidal arteries are feasible. The optimal length or preload of the choroidal arteries is attained when the internal circumference of the artery is set to 90% of the L(100).

  13. Membrane development in purple photosynthetic bacteria in response to alterations in light intensity and oxygen tension.

    PubMed

    Niederman, Robert A

    2013-10-01

    for membrane development studies in Rba. sphaeroides, the lowering of oxygen tension in chemoheterotropically growing cells results in a gratuitous formation of the ICM by an extensive membrane biogenesis process. These membrane alterations in response to lowered illumination and oxygen levels in purple bacteria are under the control of a number of interrelated two-component regulatory circuits reviewed here, which act at the transcriptional level to regulate the formation of both the pigment and apoprotein components of the LH, RC, and respiratory complexes. We have performed a proteomic examination of the ICM development process in which membrane proteins have been identified that are temporally expressed both during adaptation to low light intensity and ICM formation at low aeration and are spatially localized in both growing and mature ICM regions. For these proteomic analyses, membrane growth initiation sites and mature ICM vesicles were isolated as respective upper-pigmented band (UPB) and chromatophore fractions and subjected to clear native electrophoresis for isolation of bands containing the LH2 and RC-LH1 core complexes. In chromatophores, increasing levels of LH2 polypeptides relative to those of the RC-LH1 complex were observed as ICM membrane development proceeded during light-intensity downshifts, along with a large array of other associated proteins including high spectral counts for the F1FO-ATP synthase subunits and the cytochrome bc1 complex, as well as RSP6124, a protein of unknown function, that was correlated with increasing LH2 spectral counts. In contrast, the UPB was enriched in cytoplasmic membrane (CM) markers, including electron transfer and transport proteins, as well as general membrane protein assembly factors confirming the origin of the UPB from both peripheral respiratory membrane and sites of active CM invagination that give rise to the ICM. The changes in ICM vesicles were correlated to AFM mapping results (Adams and Hunter, Biochim

  14. Development of bovine embryos cultured in CR1aa and IVD101 media using different oxygen tensions and culture systems.

    PubMed

    Somfai, Tamás; Inaba, Yasushi; Aikawa, Yoshio; Ohtake, Masaki; Kobayashi, Shuji; Konishi, Kazuyuki; Nagai, Takashi; Imai, Kei

    2010-12-01

    The aim of the present study was to optimise the culture conditions for the in vitro production of bovine embryos. The development of in vitro fertilised bovine oocytes in CR1aa supplemented with 5% calf serum and IVD101 culture media were compared using traditional microdrops and Well of the Well (WOW) culture systems either under 5% or 20% oxygen tension. After 7 days of culture, a significantly higher blastocyst formation rate was obtained for embryos cultured in CR1aa medium compared to those cultured in IVD101, irrespective of O2 tensions and culture systems. The blastocyst formation in IVD101 was suppressed under 20% O2 compared to 5% O2 . Despite their similar total cell numbers, higher rates of inner cell mass (ICM) cells were observed in blastocysts developed in IVD101 medium than in those developed in CR1aa, irrespective of O2 tensions. There was no significant difference in blastocyst formation, total, ICM and trophectoderm (TE) cell numbers between embryos obtained by microdrop and WOW culture systems irrespective of the culture media and O2 tensions used. In conclusion, CR1aa resulted in higher blastocyst formation rates irrespective of O2 tension, whereas IVD101 supported blastocyst formation only under low O2 levels but enhanced the proliferation of ICM cells.

  15. Surface Tension

    NASA Technical Reports Server (NTRS)

    Theissen, David B.; Man, Kin F.

    1996-01-01

    The effect of surface tension is observed inmany everyday situations. For example, a slowly leaking faucet drips because the force surface tension allows the water to cling to it until a sufficient mass of water is accumulated to break free.

  16. Development of a low resource RNA extraction cassette based on surface tension valves

    PubMed Central

    Bordelon, Hali; Adams, Nicholas M.; Klemm, Amy S.; Russ, Patricia K.; Williams, John V.; Talbot, H. Keipp; Wright, David W.; Haselton, Frederick R.

    2011-01-01

    Nucleic acid-based diagnostics are highly sensitive and specific, but are easily disrupted by the presence of interferents in biological samples. In a laboratory or hospital setting, the influence of these interferents can be minimized using an RNA or DNA extraction procedure prior to analysis. However, in low resource settings, limited access to specialized instrumentation and trained personnel presents challenges that impede sample preparation. We have developed a self-contained nucleic acid extraction cassette suitable for operation in a low resource setting. This simple design contains processing solutions preloaded within a continuous length of 1.6 mm inner diameter Tygon tubing. Processing solutions are separated by air gaps and held in place during processing by the surface tension forces at the liquid-air interface, viz. surface tension valves. Nucleic acids preferentially adsorbed to silica-coated magnetic particles are separated from sample interferents by using an external magnet to transfer the nucleic acid biomarker through successive solutions to precipitate, wash and elute in the final cassette solution. The efficiency of the extraction cassette was evaluated using quantitative reverse transcriptase PCR (qRT-PCR) following extraction of respiratory syncytial virus (RSV) RNA. RNA was recovered from TE buffer or from lysates of RSV infected HEp-2 cells with 55 and 33% efficiency, respectively, of the Qiagen RNeasy kit. Recovery of RSV RNA from RSV infected HEp-2 cells was similar at 30% of the RNeasy kit. An overall limit of detection after extraction was determined to be nearly identical (97.5%) to a laboratory-based commercially available kit. These results indicate that this extraction cassette design has the potential to be an effective sample preparation device suitable for use in a low resource setting. PMID:21604768

  17. Heat changes during transient tension responses to small releases in active frog muscle.

    PubMed Central

    Gilbert, S H; Ford, L E

    1988-01-01

    Tension and heat production were measured in frog sartorius muscles in response to small shortening ramps (releases) at high and moderate speed. Transient tension responses to fast releases (0.1 to 0.4 mm in 1 or 4 ms) were similar to the tension transients length-clamped single fibers. Tension time courses during releases at 25 mm/s were like fiber responses calculated from the first two phases of the step responses (Ford et al., 1977). We conclude that similar crossbridge transitions produce tension transients observed in whole muscles and single fibers. Heat was absorbed during rapid tension recovery after fast releases and during the later part of releases at 25 mm/s. Variation of heat absorption with release size was compared with that of crossbridge movement predicted by the Huxley-Simmons hypothesis of force generation (Huxley and Simmons, 1971). Agreement between the two supports the conclusion that heat is absorbed by the crossbridge transitions responsible for rapid tension recovery after release. The results indicate that the entropy change of these transitions is positive. PMID:3265639

  18. Role of temporalis muscle over activity in chronic tension type headache: effect of yoga based management.

    PubMed

    Bhatia, R; Dureja, G P; Tripathi, M; Bhattacharjee, M; Bijlani, R L; Mathur, R

    2007-01-01

    The role of central versus peripheral mechanisms has always been questioned while explaining the etiopathogenesis of chronic tension type headache (CTTH). The following study was done to study the role of muscle spasm in CTTH. 15 patients of CTTH and 7 age matched controls were included in the study and their m. temporalis EMG was recorded for one minute each during rest, mental activity and maximal voluntary contraction and subjective pain scoring was done by visual analogue scale. The results revealed significant overactivity of m.temporalis in CTTH patients at rest when compared with control subjects (P = 0.01 and 0.03 left and right side respectively). After respective interventions namely non steroidal anti inflammatory drugs, botulinum toxin injections and yogic life style course, the EMG records revealed decrease in the mean EMG amplitude of m. temporalis during rest and mental activity more significantly after yoga based interventions (P = 0.03) and subjective pain scores decreased from 7.00 +/- 2.10 to 2.00 +/- 1.26 (P = 0.02) supporting the beneficial effect of such non invasive techniques.

  19. Tension Structure

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The fabric structure pictured is the Campus Center of La Verne College, La Verne, California. Unlike the facilities shown on the preceding pages, it is not air-supported. It is a "tension structure," its multi-coned fabric membrane supported by a network of cables attached to steel columns which function like circus tent poles. The spider-web in the accompanying photo is a computer graph of the tension pattern. The designers, Geiger-Berger Associates PC, of New York City, conducted lengthy computer analysis to determine the the best placement of columns and cables. The firm also served as structural engineering consultant on the Pontiac Silverdome and a number of other large fabric structures. Built by Birdair Structures, Inc., Buffalo, New York, the La Verne Campus Center was the first permanent facility in the United States enclosed by the space-spinoff fabric made of Owens-Corning Beta fiber glass coated with Du Pont Teflon TFE. The flexible design permits rearrangement of the interior to accommodate athletic events, student activities, theatrical productions and other recreational programs. Use of fabric covering reduced building cost 30 percent below conventional construction.

  20. Development of stiffness precedes cross-bridge attachment during the early tension rise in single frog muscle fibres.

    PubMed

    Bagni, M A; Cecchi, G; Colomo, F; Garzella, P

    1994-12-01

    1. Force responses to ramp stretches were recorded in single muscle fibres isolated from the lumbricalis muscle of the frog. Stretches were applied at rest and at progressively increasing times after a single stimulus. 2. The increase of fibre stiffness that precedes tension development has a 'static' component that accounts for the whole fibre stiffness increase during the latent period and at very low tension at the beginning of the twitch. 3. Static stiffness increase was not affected by 2,3-butanedione-2-monoxime, a drug that almost completely inhibited twitch tension. 4. Static stiffness increased approximately 5-fold as the sarcomere length was increased from 2.1 to 2.84 microns. 5. These results suggest that static fibre stiffness increase is not attributable to the formation of non-force-generating cross-bridges.

  1. "Stultifera Navis": Institutional Tensions, Conceptual Chaos, and Professional Uncertainty at the Beginning of the Decade of Education for Sustainable Development

    ERIC Educational Resources Information Center

    Perez, Jose Gutierrez; Llorente, Ma Teresa Pozo

    2005-01-01

    The main idea this article develops is the conceptual chaos, methodological tensions and epistemological conflicts that are being experienced in the field of environmental education as a result of the uncertainty generated by some institutions and international organisms. The authors' perspective starts from the idea that too many expectations…

  2. Model Development and Loads Analysis of a Wind Turbine on a Floating Offshore Tension Leg Platform

    SciTech Connect

    Matha, D.; Fischer, T.; Kuhn, M.; Jonkman, J.

    2010-02-01

    This report presents results of the analysis of a 5-MW wind turbine located on a floating offshore tension leg platform (TLP) that was conducted using the fully coupled time-domain aero-hydro-servo-elastic design code FAST with AeroDyn and HydroDyn. Models in this code are of greater fidelity than most of the models that have been used to analyze floating turbines in the past--which have neglected important hydrodynamic and mooring system effects. The report provides a description of the development process of a TLP model, which is a modified version of a Massachusetts Institute of Technology design derived from a parametric linear frequency-domain optimization process. An extensive loads and stability analysis for ultimate and fatigue loads according to the procedure of the International Electrotechnical Commission offshore wind turbine design standard was performed with the verified TLP model. Response statistics, extreme event tables, fatigue lifetimes, and selected time histories of design-driving extreme events are analyzed and presented. Loads for the wind turbine on the TLP are compared to those of an equivalent land-based turbine in terms of load ratios. Major instabilities for the TLP are identified and described.

  3. Thera-band(®) elastic band tension: reference values for physical activity.

    PubMed

    Uchida, Marco Carlos; Nishida, Márcio Makoto; Sampaio, Ricardo Aurélio Carvalho; Moritani, Toshio; Arai, Hidenori

    2016-04-01

    [Purpose] The aim of this technical note was to report significant differences in the tension forces of the different-sized Thera-band(®) elastic bands (Hygenic Corp.) determined by us versus the manufacturer. [Subjects] Two trained observers performed all measurements. [Methods] The tension force (kilogram-force units) of eight color-coded elastic bands (tan, yellow, red, green, blue, black, silver, and gold) with different resistance levels was measured at 10 different percentages of elongation (25% to 250% with 25% increments) using an electronic elongation gauge tensiometer. [Results] There were significant differences in the tension force of the elastic bands of different colors when compared in pairs (excepting the tan/yellow pair) at 100% and 200% elongation, as determined via one-way analysis of variance. There were no differences in the slopes for the tan versus yellow and green versus blue bands, as determined via linear regression analysis and one-way analysis of variance. Comparison of the tension force values obtained in our study with the reference values of the manufacturer (the t-test applied to the slopes) showed significant differences for five colors (yellow, green, blue, silver, and gold). [Conclusion] Our results indicate that the tension force values for Thera-Band elastic bands provided by the manufacturer are overestimates.

  4. Thera-band® elastic band tension: reference values for physical activity

    PubMed Central

    Uchida, Marco Carlos; Nishida, Márcio Makoto; Sampaio, Ricardo Aurélio Carvalho; Moritani, Toshio; Arai, Hidenori

    2016-01-01

    [Purpose] The aim of this technical note was to report significant differences in the tension forces of the different-sized Thera-band® elastic bands (Hygenic Corp.) determined by us versus the manufacturer. [Subjects] Two trained observers performed all measurements. [Methods] The tension force (kilogram-force units) of eight color-coded elastic bands (tan, yellow, red, green, blue, black, silver, and gold) with different resistance levels was measured at 10 different percentages of elongation (25% to 250% with 25% increments) using an electronic elongation gauge tensiometer. [Results] There were significant differences in the tension force of the elastic bands of different colors when compared in pairs (excepting the tan/yellow pair) at 100% and 200% elongation, as determined via one-way analysis of variance. There were no differences in the slopes for the tan versus yellow and green versus blue bands, as determined via linear regression analysis and one-way analysis of variance. Comparison of the tension force values obtained in our study with the reference values of the manufacturer (the t-test applied to the slopes) showed significant differences for five colors (yellow, green, blue, silver, and gold). [Conclusion] Our results indicate that the tension force values for Thera-Band elastic bands provided by the manufacturer are overestimates. PMID:27190465

  5. Lattice spacing changes accompanying isometric tension development in intact single muscle fibers.

    PubMed

    Bagni, M A; Cecchi, G; Griffiths, P J; Maéda, Y; Rapp, G; Ashley, C C

    1994-11-01

    The myosin lattice spacing of single intact muscle fibers of the frog, Rana temporaria, was studied in Ringer's solution (standard osmolarity 230 mOsm) and hyper- and hypotonic salines (1.4 and 0.8 times standard osmolarity respectively) in the relaxed state, during "fixed end" tetani, and during shortening, using synchrotron radiation. At standard tonicity, a tetanus was associated with an initial brief lattice expansion (and a small amount of sarcomere shortening), followed by a slow compression (unaccompanied by sarcomere length changes). In hypertonic saline (myosin lattice compressed by 8.1%), these spacing changes were suppressed, in hypotonic saline (lattice spacing increased by 7.5%), they were enhanced. During unloaded shortening of activated fibers, a rapid lattice expansion occurred at all tonicities, but became larger as tonicity was reduced. This expansion was caused in part by the change in length of the preparation, but also by a recoil of a stressed radial compliance associated with axial force. The lattice spacing during unloaded shortening was equal to or occasionally greater than predicted for a relaxed fiber at that sarcomere length, indicating that the lattice compression associated with activation is rapidly reversed upon loss of axial force. Lattice recompression occurred upon termination of shortening under standard and hypotonic conditions, but was almost absent under hypertonic conditions. These observations indicate that axial cross-bridge tension is associated with a compressive radial force in intact muscle fibers at full overlap; however, this radial force exhibits a much greater sensitivity to lattice spacing than does the axial force.

  6. Development Education and Multi-Ethnic Education: Some Tensions. Development Education Paper No. 21.

    ERIC Educational Resources Information Center

    Storm, Michael

    The document examines the relationships between multi-ethnic and development education in Great Britain. Multi-ethnic education, initially with a national focus, has a global dimension, and development education, initially with a global focus, has a national and even local dimension. A common interest in human diversity and human inequalities…

  7. G-fibre cell wall development in willow stems during tension wood induction

    PubMed Central

    Gritsch, Cristina; Wan, Yongfang; Mitchell, Rowan A. C.; Shewry, Peter R.; Hanley, Steven J.; Karp, Angela

    2015-01-01

    Willows (Salix spp.) are important as a potential feedstock for bioenergy and biofuels. Previous work suggested that reaction wood (RW) formation could be a desirable trait for biofuel production in willows as it is associated with increased glucose yields, but willow RW has not been characterized for cell wall components. Fasciclin-like arabinogalactan (FLA) proteins are highly up-regulated in RW of poplars and are considered to be involved in cell adhesion and cellulose biosynthesis. COBRA genes are involved in anisotropic cell expansion by modulating the orientation of cellulose microfibril deposition. This study determined the temporal and spatial deposition of non-cellulosic polysaccharides in cell walls of the tension wood (TW) component of willow RW and compared it with opposite wood (OW) and normal wood (NW) using specific antibodies and confocal laser scanning microscopy and transmission electron microscopy. In addition, the expression patterns of an FLA gene (SxFLA12) and a COBRA-like gene (SxCOBL4) were compared using RNA in situ hybridization. Deposition of the non-cellulosic polysaccharides (1–4)-β-D-galactan, mannan and de-esterified homogalacturonan was found to be highly associated with TW, often with the G-layer itself. Of particular interest was that the G-layer itself can be highly enriched in (1–4)-β-D-galactan, especially in G-fibres where the G-layer is still thickening, which contrasts with previous studies in poplar. Only xylan showed a similar distribution in TW, OW, and NW, being restricted to the secondary cell wall layers. SxFLA12 and SxCOBL4 transcripts were specifically expressed in developing TW, confirming their importance. A model of polysaccharides distribution in developing willow G-fibre cells is presented. PMID:26220085

  8. G-fibre cell wall development in willow stems during tension wood induction.

    PubMed

    Gritsch, Cristina; Wan, Yongfang; Mitchell, Rowan A C; Shewry, Peter R; Hanley, Steven J; Karp, Angela

    2015-10-01

    Willows (Salix spp.) are important as a potential feedstock for bioenergy and biofuels. Previous work suggested that reaction wood (RW) formation could be a desirable trait for biofuel production in willows as it is associated with increased glucose yields, but willow RW has not been characterized for cell wall components. Fasciclin-like arabinogalactan (FLA) proteins are highly up-regulated in RW of poplars and are considered to be involved in cell adhesion and cellulose biosynthesis. COBRA genes are involved in anisotropic cell expansion by modulating the orientation of cellulose microfibril deposition. This study determined the temporal and spatial deposition of non-cellulosic polysaccharides in cell walls of the tension wood (TW) component of willow RW and compared it with opposite wood (OW) and normal wood (NW) using specific antibodies and confocal laser scanning microscopy and transmission electron microscopy. In addition, the expression patterns of an FLA gene (SxFLA12) and a COBRA-like gene (SxCOBL4) were compared using RNA in situ hybridization. Deposition of the non-cellulosic polysaccharides (1-4)-β-D-galactan, mannan and de-esterified homogalacturonan was found to be highly associated with TW, often with the G-layer itself. Of particular interest was that the G-layer itself can be highly enriched in (1-4)-β-D-galactan, especially in G-fibres where the G-layer is still thickening, which contrasts with previous studies in poplar. Only xylan showed a similar distribution in TW, OW, and NW, being restricted to the secondary cell wall layers. SxFLA12 and SxCOBL4 transcripts were specifically expressed in developing TW, confirming their importance. A model of polysaccharides distribution in developing willow G-fibre cells is presented.

  9. The effects of caffeine on tension development and intracellular calcium transients in rat ventricular muscle.

    PubMed Central

    Konishi, M; Kurihara, S; Sakai, T

    1984-01-01

    The effects of caffeine on tension and intracellular [Ca2+] were investigated in rat ventricular muscle using the Ca2+-sensitive photoprotein, aequorin. Contracture was induced by rapid application of 0.5-10 mM-caffeine solution at 20 degrees C. In normal Tyrode solution at 8 degrees C, or in Na+-deficient solution in which Na+ was isotonically replaced by sucrose, peak tension of caffeine contracture was potentiated and relaxation was prolonged. Caffeine contracture could not be induced immediately after a prior contracture. Repriming time was 10 min in Tyrode solution, and was much shorter in Na+-deficient solution or in high-K+ solution containing 105.9 mM-K+. Caffeine prolonged the plateau of action potential dose dependently. At low temperature, prolongation of the plateau phase by caffeine was more marked. Twitch tension showed a triphasic change after application of caffeine; peak tension transiently increased in a potentiating phase (P phase), and then decreased below control level in an inhibitory phase (I phase) followed by gradual recovery in a recovery phase (R phase). The effects of caffeine on the Ca2+ transients during a twitch were also complex, depending on time after application and dose of caffeine. In low caffeine concentration (below 0.5 mM) the peak of the Ca2+ transient was potentiated in the I phase, although the peak tension was suppressed. At high concentration (above 3 mM) the peaks of both the Ca2+ transient and twitch tension were suppressed. In every concentration of caffeine tested (0.1-5 mM), time to the Ca2+ transient and twitch tension peaks was prolonged, and the falling phases of both were delayed. Caffeine might release Ca2+ from intracellular store(s) and enhance the slow inward current. The Ca2+ transient obtained in this study clearly indicate that the prolonged time to peak tension in the presence of caffeine is due to the slow rise of intracellular [Ca2+] and prolonged time to peak of the Ca2+ transient. It is also quite

  10. Influence of constriction, wall tension, smooth muscle activation and cellular deformation on rat resistance artery vasodilator reactivity.

    PubMed

    Colton, Ilsley; Mandalà, Maurizio; Morton, Jude; Davidge, Sandra T; Osol, George

    2012-01-01

    This study investigated how vasoconstriction (tone), wall tension, smooth muscle activation, and vascular wall deformation influence resistance artery vasodilator reactivity. Resistance arteries, from two different regional circulations (splanchnic, uterine) and from pregnant and non-pregnant rats, were cannulated and pressurized, or mounted on a wire myograph under isometric conditions prior to being exposed to both endothelium-dependent (acetylcholine, ACh) and -independent (sodium nitroprusside, SNP) vasodilator agonists. A consistent pattern of reduced vasodilator sensitivity was noted as a function of extent of preconstriction for both agonists noted in pressurized arteries. A similar pattern regarding activation was noted in wire-mounted arteries in response to SNP but not ACh. Wall tension proved to be a major determinant of vascular smooth muscle vasodilator reactivity and its normalization reversed this pattern, as more constricted vessels were more sensitive to ACh relaxation without any change in SNP sensitivity, suggesting that endothelial deformation secondary to vasoconstriction augments its vasodilator output. To our knowledge, this is the first study to dissect out the complex interplay between biophysical forces impinging on VSM (pressure, wall tension), the ambient level of tone (vasoconstriction, smooth muscle cell activation), and consequences of cellular (particularly endothelial) deformation secondary to constriction in determining resistance artery vasodilatory reactivity.

  11. Development of indirect ring tension test for fracture characterization of asphalt mixtures

    NASA Astrophysics Data System (ADS)

    Zeinali Siavashani, Alireza

    Low temperature cracking is a major distress in asphalt pavements. Several test configurations have been introduced to characterize the fracture properties of hot mix (HMA); however, most are considered to be research tools due to the complexity of the test methods or equipment. This dissertation describes the development of the indirect ring tension (IRT) fracture test for HMA, which was designed to be an effective and user-friendly test that could be deployed at the Department of Transportation level. The primary advantages of this innovative and yet practical test include: relatively large fracture surface test zone, simplicity of the specimen geometry, widespread availability of the required test equipment, and ability to test laboratory compacted specimens as well as field cores. Numerical modeling was utilized to calibrate the stress intensity factor formula of the IRT fracture test for various specimen dimensions. The results of this extensive analysis were encapsulated in a single equation. To develop the test procedure, a laboratory study was conducted to determine the optimal test parameters for HMA material. An experimental plan was then developed to evaluate the capability of the test in capturing the variations in the mix properties, asphalt pavement density, asphalt material aging, and test temperature. Five plant-produced HMA mixtures were used in this extensive study, and the results revealed that the IRT fracture test is highly repeatable, and capable of capturing the variations in the fracture properties of HMA. Furthermore, an analytical model was developed based on the viscoelastic properties of HMA to estimate the maximum allowable crack size for the pavements in the experimental study. This analysis indicated that the low-temperature cracking potential of the asphalt mixtures is highly sensitive to the fracture toughness and brittleness of the HMA material. Additionally, the IRT fracture test data seemed to correlate well with the data from

  12. Access, Cost and Quality: Tensions in the Development of Primary Education in Kenya

    ERIC Educational Resources Information Center

    Somerset, Anthony

    2011-01-01

    Throughout Kenya's history, tensions between two goals have characterised the educational policy debate: first, the expansion of access; second, the containment of costs. During the colonial period, cost-containment predominated, leading to severe restrictions on access and massive unmet social demand. Then, during post-Independence years,…

  13. The Clash of Cultures: Hybrid Learning Course Development as Management of Tension

    ERIC Educational Resources Information Center

    Cowie, Peter; Nichols, Mark

    2010-01-01

    Using a case study approach, this paper considers e-learning project management from the perspective of navigating tension between faculty and instructional design/e-learning expertise, in the context of as the bridging of two distinctive cultures. The diffusion of e-learning in an institution where, historically, faculty have been independent…

  14. Culture of bovine embryos in polyester mesh sections: the effect of pore size and oxygen tension on in vitro development.

    PubMed

    Somfai, T; Inaba, Y; Aikawa, Y; Ohtake, M; Kobayashi, S; Akai, T; Hattori, H; Konishi, K; Imai, K

    2010-12-01

    The purpose of this study was to assess the feasibility of polyester mesh culture for the in vitro production of bovine embryos, as polyester mesh is an alternative way for tracking individual embryos throughout culture using time-lapse cinematography (TLC). Bovine embryos were isolated during in vitro culture using sections of three different polyethylene terephthalate (PET) mesh products. In vitro matured and fertilized bovine oocytes were cultured in the 217 × 217, 230 × 230 or 238 × 238-μm openings of PET mesh sections or in simple micro-drops (control) for 7 days under either 20% or 5% O(2) tensions. No difference in embryo developmental rates was found between the culture groups in terms of cleavage, blastocyst formation and blastocyst expansion irrespective of O(2) tension. In contrast, under 20% O(2) tension, blastocysts that developed in PET mesh with 217 × 217-μm opening had significantly higher numbers of total and trophectoderm (TE) cells than control embryos; however, the numbers and proportions of inner cell mass (ICM) cells did not differ. Under 5% O(2) tension, no difference was found among the culture groups in the numbers of total, ICM and TE cells in embryos. All three PET mesh products investigated in this study were proven to be effective to prevent embryo movement. The results demonstrate that bovine embryos can be cultured in PET mesh sections without negative side-effects and suggest that embryo distance determined by the mesh affects embryo quality at atmospheric oxygen tension. Polyethylene terephthalate mesh with 217 × 217-μm openings was found to be the most suitable for further application in TLC.

  15. Evidence for propagating, active tensional faulting in Upper Kåfjord valley, Troms County, Norway

    NASA Astrophysics Data System (ADS)

    Redfield, T. F.; Osmundsen, P. T.; Henderson, I. H. C.; Hermanns, R. L.

    2010-05-01

    New concepts governing margin extension and post-rift passive margin evolution are appearing from onshore and offshore studies. In Norway topographic escarpments, creation, preservation and destruction of landforms, and drainage patterns are related to structural templates created during the Jurassic rift phase. Contradicting the notion that post-rift isostatic compensation, thermal subsidence, and topographic degradation mark a passive margin's final evolutionary phases, we present geological evidence for currently-active tensional deformation, accommodated by release faulting, in uppermost Kåfjordalen and Signaldalen. In Signaldalen, propagation of the deformation tip has introduced active normal faulting to Finland. Ground observations indicate a large normal fault defines the eastern border of the Lyngen 'Alps' peninsula. There, a series of exceptionally well-preserved triangular facets adorn a sharp, elevated escarpment. To the east a swarm of small NE-trending normal faults are exposed in roadside outcrops near the mouth of Kåfjord, dipping both to the NW and SE. Displacement across the fault swarm is asymmetric, the greatest component of motion being down-to-the-NW in the direction of the Lyngen Fault. Another set of NE trending, NW dipping faults crop out at Revsdalfjellet. We interpret these faults to reflect splays to the Lyngen Fault. The hanging wall of the Lyngen Fault is characterized by numerous clusters of fault-controlled rockslides. We interpret the valleys of Signaldalen, Skibotndalen, and Kåfjordalen, located in the hanging wall of the Lyngen Fault, to have formed at least partly under the influence of release faults that accommodated hanging wall flexure and failure. Other fault scarps, trending more NW-SE, crop out at two Kåfjord rockslide sites, Nomandalstinden and Litledalen. Mineralized surfaces exhibiting dip-slip slickenlines indicate most of these faults are true tectonic features, not simply gravitationally-driven 'sackung' planes

  16. Using noncontact AFM frequency shifts to determine stereocilia bundle stiffness and tension in the developing cochlear sensory epithelium

    NASA Astrophysics Data System (ADS)

    Chadwick, Richard S.; Cartagena-Rivera, Alexander X.

    2015-12-01

    Measurement of frequency shifts of cantilevers having an attached microsphere oscillating at acoustic frequencies can be used to assess mechanical properties of cochlear structures. The method has already been reported for measuring elastic and viscous properties of the tectorial membrane. We describe here how the method can be used to examine other cochlear structures. Theory and formulas for relating hair bundle stiffness and tension in the developing cochlear sensory epithelium to measured frequency shifts are given to estimate the expected frequency shifts and show feasibility of the measurements. We show through a molecular model of myosin II located along the edges of confluent hexagons that myosin contractile forces are balanced by isotropic tension in the developing confluent sheet of cells.

  17. Web Tension regulation of multispan roll-to-roll system using integrated active dancer and load cells for printed electronics applications

    NASA Astrophysics Data System (ADS)

    Zubair, Muhammad; Ponniah, Ganeshthangaraj; Yang, Young Jin; Choi, Kyung Hyun

    2014-03-01

    The mass production of printed electronics can be achieved by roll-to-roll(R2R) printing system, so highly accurate web tension is required that can minimize the register error and keep the thickness and roughness of printed devices in limits. The web tension of a R2R system is regulated by the use of integrated load cells and active dancer system for printed electronics applications using decentralized multi-input-single-output(MISO) regularized variable learning rate backpropagation artificial neural networks. The active dancer system is used before printing system to reduce disturbances in the web tension of process span. The classical PID control result in tension spikes with the change in roll diameter of winder and unwinder rolls. The presence of dancer in R2R system shows that improved web tension control in printing span and the web tension can be enhanced from 3.75 N to 4.75 N. The overshoot of system is less than ±2.5 N and steady state error is within ±1 N where load cells have a signal noise of ±0.7 N. The integration of load cells and active dancer with self-adapting neural network control provide a solution to the web tension control of multispan roll-to-roll system.

  18. Tension on JAM-A activates RhoA via GEF-H1 and p115 RhoGEF.

    PubMed

    Scott, David W; Tolbert, Caitlin E; Burridge, Keith

    2016-05-01

    Junctional adhesion molecule A (JAM-A) is a broadly expressed adhesion molecule that regulates cell-cell contacts and facilitates leukocyte transendothelial migration. The latter occurs through interactions with the integrin LFA-1. Although we understand much about JAM-A, little is known regarding the protein's role in mechanotransduction or as a modulator of RhoA signaling. We found that tension imposed on JAM-A activates RhoA, which leads to increased cell stiffness. Activation of RhoA in this system depends on PI3K-mediated activation of GEF-H1 and p115 RhoGEF. These two GEFs are further regulated by FAK/ERK and Src family kinases, respectively. Finally, we show that phosphorylation of JAM-A at Ser-284 is required for RhoA activation in response to tension. These data demonstrate a direct role of JAM-A in mechanosignaling and control of RhoA and implicate Src family kinases in the regulation of p115 RhoGEF.

  19. Tension on JAM-A activates RhoA via GEF-H1 and p115 RhoGEF

    PubMed Central

    Scott, David W.; Tolbert, Caitlin E.; Burridge, Keith

    2016-01-01

    Junctional adhesion molecule A (JAM-A) is a broadly expressed adhesion molecule that regulates cell–cell contacts and facilitates leukocyte transendothelial migration. The latter occurs through interactions with the integrin LFA-1. Although we understand much about JAM-A, little is known regarding the protein’s role in mechanotransduction or as a modulator of RhoA signaling. We found that tension imposed on JAM-A activates RhoA, which leads to increased cell stiffness. Activation of RhoA in this system depends on PI3K-mediated activation of GEF-H1 and p115 RhoGEF. These two GEFs are further regulated by FAK/ERK and Src family kinases, respectively. Finally, we show that phosphorylation of JAM-A at Ser-284 is required for RhoA activation in response to tension. These data demonstrate a direct role of JAM-A in mechanosignaling and control of RhoA and implicate Src family kinases in the regulation of p115 RhoGEF. PMID:26985018

  20. Analysis of dimensions, activation and median frequency of cervical flexor muscles in young women with migraine or tension-type headache

    PubMed Central

    Wanderley, Débora; Moura, Alberto G.; Costa, Joaquim J. S.; Siqueira, Gisela R.; de Oliveira, Daniella A.

    2015-01-01

    Background: Central and peripheral mechanisms may be involved in migraine and tension-type headache pathogenesis, however the role of muscle disorders in their pathophysiological mechanisms remains unclear. Objectives: To assess the association between the presence of migraine or tension-type headache and changes in longus colli muscle dimensions and sternocleidomastoid muscle activity. Method: An observational study with 48 women comparing the following groups: migraine (n=21), tension-type headache (n=16), and control (n=11). The cross-sectional area, lateral and anteroposterior dimensions, and shape ratio of the longus colli muscle were measured using ultrasound. The activation of the sternocleidomastoid muscle was assessed by signal amplitude and the decline in median frequency using surface electromyographic analysis. Results: The dimensions of the longus colli muscle did not differ between groups (p>0.05). Post-test analysis showed lower sternocleidomastoid muscle activation on both sides, at the onset of contraction, in the group with tension-type headache when compared to the control group {right sternocleidomastoid [tension-type headache: 0.39 (0.30-0.49); control: 0.58 (0.42-0.76); p=0.026] and left sternocleidomastoid [tension-type headache: 0.39 (0.31-0.48); control: 0.60 (0.42-0.79); p=0.039], Tukey's post hoc test}. There was no difference between the three groups in sternocleidomastoid muscle activation, on both sides, at the end of contraction (p>0.05). Intergroup analysis showed no difference in the rate of decline in median frequency (p>0.05). Conclusion: The group with tension-type headache exhibited less activation at the onset of sternocleidomastoid muscle contraction. No association was observed between the presence of headache and alterations in longus colli muscle dimensions, median frequency, and sternocleidomastoid muscle activation at the end of contraction. PMID:26083605

  1. Lamellipodial tension, not integrin/ligand binding, is the crucial factor to realise integrin activation and cell migration.

    PubMed

    Schulte, Carsten; Ferraris, Gian Maria Sarra; Oldani, Amanda; Galluzzi, Massimiliano; Podestà, Alessandro; Puricelli, Luca; de Lorenzi, Valentina; Lenardi, Cristina; Milani, Paolo; Sidenius, Nicolai

    2016-01-01

    The molecular clutch (MC) model proposes that actomyosin-driven force transmission permits integrin-dependent cell migration. To investigate the MC, we introduced diverse talin (TLN) and integrin variants into Flp-In™ T-Rex™ HEK293 cells stably expressing uPAR. Vitronectin variants served as substrate providing uPAR-mediated cell adhesion and optionally integrin binding. This particular system allowed us to selectively analyse key MC proteins and interactions, effectively from the extracellular matrix substrate to intracellular f-actin, and to therewith study mechanobiological aspects of MC engagement also uncoupled from integrin/ligand binding. With this experimental approach, we found that for the initial PIP2-dependent membrane/TLN/f-actin linkage and persistent lamellipodia formation the C-terminal TLN actin binding site (ABS) is dispensable. The establishment of an adequate MC-mediated lamellipodial tension instead depends predominantly on the coupling of this C-terminal TLN ABS to the actomyosin-driven retrograde actin flow force. This lamellipodial tension is crucial for full integrin activation eventually determining integrin-dependent cell migration. In the integrin/ligand-independent condition the frictional membrane resistance participates to these processes. Integrin/ligand binding can also contribute but is not necessarily required.

  2. Surface Tension

    SciTech Connect

    2011-01-01

    Surface tension in the kitchen sink. At Berkeley Lab's Molecular Foundry, scientists study surface tension to understand how molecules "self-assemble." The coin trick in the video uses the re-arrangement of water molecules to seemingly create order out of disorder. The same principle can be used to create order in otherwise hard-to-handle nano materials. Scientists can then transfer these ordered materials onto surfaces by dipping them through the air-water interface, or (as we've recently shown) squeeze them so that they collapse into the water as two-molecule-thick nano sheets. http://newscenter.lbl.gov/feature-stories/2011/10/17/shaken-not-stirred/

  3. Blood Vessel Tension Tester

    NASA Technical Reports Server (NTRS)

    1978-01-01

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

  4. Algorithm-development activities

    NASA Technical Reports Server (NTRS)

    Carder, Kendall L.

    1994-01-01

    The task of algorithm-development activities at USF continues. The algorithm for determining chlorophyll alpha concentration, (Chl alpha) and gelbstoff absorption coefficient for SeaWiFS and MODIS-N radiance data is our current priority.

  5. Balancing the Tensions and Meeting the Conceptual Challenges of Education for Sustainable Development and Climate Change

    ERIC Educational Resources Information Center

    Blum, Nicole; Nazir, Joanne; Breiting, Soren; Goh, Kim Chuan; Pedretti, Erminia

    2013-01-01

    This paper addresses one of the key challenges for work on education, sustainable development and climate change: the overall conceptualisation of central ideas such as Environmental Education (EE), Education for Sustainable Development (ESD) and Climate Change Education (CCE). What do these concepts mean in diverse contexts and amongst diverse…

  6. Tensions in a Nepali Telecenter: An Ethnographic Look at Progress Using Activity Theory

    ERIC Educational Resources Information Center

    Lee, Jeffrey Chih-Yih

    2010-01-01

    Developing countries such as Nepal struggle to keep up technologically. While advances make it possible for average Nepalis to access mobile phones, computers, and digital cameras, barriers impede access. As with other governments (Huerta & Rodrigo, 2007; Mokhtarian & Meenakshisun, 2002), Nepal responded in 2004 with telecenters to push…

  7. The Development of Australia's National Training System: A Dynamic Tension between Consistency and Flexibility. Occasional Paper

    ERIC Educational Resources Information Center

    Bowman, Kaye; McKenna, Suzy

    2016-01-01

    This occasional paper provides an overview of the development of Australia's national training system and is a key knowledge document of a wider research project "Consistency with flexibility in the Australian national training system." This research project investigates the various approaches undertaken by each of the jurisdictions to…

  8. Universities and Regional Development: A Critical Assessment of Tensions and Contradictions. International Studies in Higher Education

    ERIC Educational Resources Information Center

    Pinheiro, Romulo, Ed.; Benneworth, Paul, Ed.; Jones, Glen A., Ed.

    2012-01-01

    Universities are under increasing pressure to help promote socio-economic growth in their local communities. However until now, no systematic, critical attention has been paid to the factors and mechanisms that currently make this process so daunting. In Universities and Regional Development, scholars from Europe, the Americas, Africa, and Asia…

  9. Dynamic Tensions: Early Reflections from MDRC's Evaluation of the Innovative Professional Development Challenge

    ERIC Educational Resources Information Center

    MDRC, 2015

    2015-01-01

    In the Innovative Professional Development (iPD) Challenge, the Bill & Melinda Gates Foundation has invested in helping school districts and networks redesign their instructional support systems to better support educators in increasing student success. This Issue Focus, the second in a series, presents early reflections from MDRC's evaluation…

  10. Developing and Presenting a Teaching Persona: The Tensions of Secondary Preservice Teachers

    ERIC Educational Resources Information Center

    Davis, Janine S.

    2012-01-01

    This qualitative, multiple case study investigated the ways that three preservice secondary teachers developed, presented, and considered their teaching personae. Data for each participant consisted of three interviews, field observations of both teaching and non-teaching, data collection of lessons and class documents, and four journal…

  11. Employability Development in the Context of Doctoral Studies: Systemic Tensions and the Views of Key Stakeholders

    ERIC Educational Resources Information Center

    Golovushkina, Elena; Milligan, Colin

    2013-01-01

    Although the employability of doctoral candidates has been a topic of much discussion, the views of key institutional stakeholders on the subject are little understood. In order to address this gap, this study explores the perceptions of doctoral candidates, supervisors and researcher developers through semi-structured interviews. This small-scale…

  12. Evoked activity in the hypothalamus and amygdala of the cat in conditions of food-related motivation and emotional tension.

    PubMed

    Pavlova, I V; Vanetsian, G L

    2006-02-01

    The amplitude-time characteristics of potentials evoked by clicks were analyzed in bilateral leads from the lateral hypothalamus and amygdala in cats in conditions of food-related motivation, emotional tension (presentation of dogs), and orientational reactions. In conditions of food-related motivation, as compared with the satiated state, there were decreases in the latent periods and changes in the amplitudes of the P1 and N2 components in the hypothalamus and P1, N2, and N3 in the amygdala. The most marked changes occurred on the left side in both structures. Presentation of dogs induced decreases in the latent periods of all components (including N1) of evoked potentials in the hypothalamus and amygdala, the most marked changes in the hypothalamus occurring on the right side and the most marked changes in the amygdala occurring on the left side. Conversely, orientational reactions to emotionally neutral stimuli induced increases in the latent periods of evoked potentials. It is concluded that there is an increase in sensory reactivity in the hypothalamus and amygdala in motivational-emotional states. It is suggested that the side of dominance in these structures may be associated both with the factor of the activity/passivity of the behavior in conditions of fear and the genesis of the emotion (motivational or informational).

  13. Development, pre-qualification, and production history of 60 ksi UOE steel tendon pipe for AUGER tension leg platform

    SciTech Connect

    Takeuchi, Izumi; Nishimoto, Koji; Nagase, Makoto; Nishizawa, Masashi; Smith, J.D.; Bowen, K.G. |

    1995-12-31

    AUGER Tension Leg Platform (TLP) tendons consisted of specially designed threaded forged connections welded to thick-walled tubular tendon segments. This paper describes the development, pre-qualification testing, and production properties of the 60ksi-26 in. O.D. x 1.300 in. wall-thickness steel pipes which formed the TLP tendon segments. The tendon pipe segments were manufactured by the UOE process using Thermo-Mechanical Control Process (TMCP) steel plate with double-submerged arc seam welding (DSAW). Stringent mechanical properties and dimensional control requirements were established for the tendon pipes, with special emphasis on weldability and resulting high heat-affected-zone (HAZ) crack-tip opening displacement (CTOD) fracture toughness. The weldability (hydrogen delayed cracking resistance) and fracture toughness of the HAZ showed high and stable performance. Tight dimensional control, especially ovality, ensured minimal high-low during the making of girth welds at the construction site. Limiting high-low is an important parameter for lowering local stress-concentration factor (SCF) and increasing fatigue life. These results are discussed with particular reference to the steel Local Brittle Zone (LBZ) concept. Narrow range control of the TMCP steel chemistry, plate manufacturing process, and UOE pipe-forming and seam-welding process insured that all requirements were met for the production quantity.

  14. Relationship of active trigger points with related disability and anxiety in people with tension-type headache

    PubMed Central

    Palacios-Ceña, María; Castaldo, Matteo; Wang, Kelun; Catena, Antonella; Torelli, Paola; Arendt-Nielsen, Lars; Fernández-de-las-Peñas, César

    2017-01-01

    Abstract To investigate the differences in the presence of trigger points (TrPs) and their association with headache-related disability and mood disorders in people with frequent episodic tension-type headache (TTH) (FETTH) and chronic TTH (CTTH). One hundred twenty-two individuals with TTH participated. Clinical features of headache (i.e., intensity, duration, and frequency) were recorded on a headache diary. Headache-related disability was assessed with the Headache Disability Inventory, trait and state anxiety levels with State-Trait Anxiety Inventory, and depression with the Hospital Anxiety and Depression Scale. TrPs were bilaterally explored in the temporalis, masseter, suboccipital, upper trapezius, splenius capitis, and sternocleidomastoid muscles. Sixty-two (51%) patients were classified as FETTH, whereas 60 (49%) were classified as CTTH. Individuals with CTTH showed higher burden of headache and depression than FETTH (P < 0.001). Subjects with FETTH showed similar number of TrPs (total number: 5.9 ± 3.1, active TrPs: 4.7 ± 2.5, and latent TrPs: 1.2 ± 1.9) than those with CTTH (total number: 5.7 ± 3.2, active TrPs: 4.2 ± 3.0, and latent TrPs: 1.5 ± 1.8). The number of active TrPs was significantly associated with the burden of headache (r = 0.189; P = 0.037) and trait anxiety (r = 0.273; P = 0.005): the higher the number of active TrPs, the greater the physical burden of headache or the more the trait anxiety level. No association with the depression was observed. The presence of active TrPs in head and neck/shoulder muscles was similar between individuals with FETTH and CTTH and associated with the physical burden of headache and trait anxiety levels independently of the subgroup of TTH. PMID:28353618

  15. Localized Torsional Tension in the DNA of Human Cells

    NASA Astrophysics Data System (ADS)

    Ljungman, Mats; Hanawalt, Philip C.

    1992-07-01

    Torsional tension in DNA may be both a prerequisite for the efficient initiation of transcription and a consequence of the transcription process itself with the generation of positive torsional tension in front of the RNA polymerase and negative torsional tension behind it. To examine torsional tension in specific regions of genomic DNA in vivo, we developed an assay using photoactivated psoralen as a probe for unconstrained DNA superhelicity and x-rays as a means to relax DNA. Psoralen intercalates more readily into DNA underwound by negative torsional tension than into relaxed DNA, and it can form interstrand DNA cross-links upon UVA irradiation. By comparing the amount of psoralen-induced DNA cross-links in cells irradiated with x-rays either before or after the psoralen treatment, we examined the topological state of the DNA in specific regions of the genome in cultured human 6A3 cells. We found that although no net torsional tension was detected in the bulk of the genome, localized tension was prominent in the DNA of two active genes. Negative torsional tension was found in the 5' end of the amplified dihydrofolate reductase gene and in a region near the 5' end of the 45S rRNA transcription unit, whereas a low level of positive torsional tension was found in a region near the 3' end of the dihydrofolate reductase gene. These results document an intragenomic heterogeneity of DNA torsional tension and lend support to the twin supercoiled domain model for transcription in the genome of intact human cells.

  16. Negotiating Tensions Between Theory and Design in the Development of Mailings for People Recovering From Acute Coronary Syndrome

    PubMed Central

    Presseau, Justin; Nicholas Angl, Emily; Jokhio, Iffat; Schwalm, JD; Grimshaw, Jeremy M; Bosiak, Beth; Natarajan, Madhu K; Ivers, Noah M

    2017-01-01

    interdisciplinary team discussions to interpret findings in the context of relevant theory-based evidence and iteratively adapted the intervention accordingly. Results Through our iterative development and testing, we identified 3 key tensions: (1) evidence from theory-based studies versus users’ feelings, (2) informative versus persuasive communication, and (3) logistical constraints for the intervention versus users’ desires or preferences. We addressed these by (1) identifying root causes for users’ feelings and addressing those to better incorporate theory- and evidence-based features, (2) accepting that our intervention was ethically justified in being persuasive, and (3) making changes to the intervention where possible, such as attempting to match imagery in the materials to patients’ self-images. Conclusions Theory-informed interventions must be operationalized in ways that fit with user needs. Tensions between users’ desires or preferences and health care system goals and constraints must be identified and addressed to the greatest extent possible. A cluster randomized controlled trial of the final intervention is currently underway. PMID:28249831

  17. Advancements in the development of a directional-position sensing fast neutron detector using acoustically tensioned metastable fluids

    NASA Astrophysics Data System (ADS)

    Archambault, Brian C.; Webster, Jeffrey A.; Grimes, Thomas F.; Fischer, Kevin F.; Hagen, Alex R.; Taleyakhan, Rusi P.

    2015-06-01

    Advancements in the development of a direction and position sensing fast neutron detector which utilizes the directional acoustic tensioned metastable fluid detector (D-ATMFD) are described. The resulting D-ATMFD sensor is capable of determining the direction of neutron radiation with a single compact detector versus use of arrays of detectors in conventional directional systems. Directional neutron detection and source positioning offer enhanced detection speeds in comparison to traditional proximity searching; including enabling determination of the neutron source shape, size, and strength in near real time. This paper discusses advancements that provide the accuracy and precision of ascertaining directionality and source localization information utilizing enhanced signal processing-cum-signal analysis, refined computational algorithms, and on-demand enlargement capability of the detector sensitive volume. These advancements were accomplished utilizing experimentation and theoretical modeling. Benchmarking and qualifications studies were successfully conducted with random and fission based special nuclear material (SNM) neutron sources (239Pu-Be and 252Cf). These results of assessments have indicated that the D-ATMFD compares well in technical performance with banks of competing directional fast neutron detector technologies under development worldwide, but it does so with a single detector unit, an unlimited field of view, and at a significant reduction in both cost and size while remaining completely blind to common background (e.g., beta-gamma) radiation. Rapid and direct SNM neutron source imaging with two D-ATMFD sensors was experimentally demonstrated, and furthermore, validated via multidimensional nuclear particle transport simulations utilizing MCNP-PoliMi. Characterization of a scaled D-ATMFD based radiation portal monitor (RPM) as a cost-effective and efficient 3He sensor replacement was performed utilizing MCNP-PoliMi simulations, the results of which

  18. Muscular factors are of importance in tension-type headache.

    PubMed

    Jensen, R; Bendtsen, L; Olesen, J

    1998-01-01

    Recent studies have indicated that muscular disorders may be of importance for the development of increased pain sensitivity in patients with chronic tension-type headache. The objective of the present study was to investigate this hypothesis by examining the pain perception in tension-type headache with and without muscular disorders defined as increased tenderness. We examined 28 patients with episodic tension-type headache, 28 patients with chronic tension-type headache, and 30 healthy controls. Pericranial myofascial tenderness was recorded with manual palpation, and pressure pain detection and tolerances in cephalic and extracephalic locations with an electronic pressure algometer. In addition, thermal pain sensitivity and electromyographic activity were recorded. The main result was significantly lower pressure pain detection thresholds and tolerances in all the examined locations in patients with chronic tension-type headache with a muscular disorder compared to those without a muscular disorder. There were no such differences in any of the examined locations when the two subgroups of patients with episodic tension-type headache were compared. Thermal pain sensitivity did not differ between patients with and without a muscular disorder, while electromyographic activity levels were significantly higher in patients with chronic tension-type headache with than in those without a muscular disorder. Our results strongly indicate that prolonged nociceptive stimuli from the pericranial myofascial tissue sensitize the central nervous system and, thereby, lead to an increased general pain sensitivity. Muscular factors may, therefore, be of major importance for the conversion of episodic into chronic tension-type headache. The present study complements the understanding of the important interactions between peripheral and central factors in tension-type headache and may lead to a better prevention and treatment of the most prevalent type of headache.

  19. CNES gondola development activities

    NASA Astrophysics Data System (ADS)

    Vargas, André; Verdier, Nicolas; Escarnot, Jean-Pierre; Vargas, André

    Recent safety rules and gondola obsolescence oblige CNES to initiate new developments to improve performances according scientific needs. A large project called NOSYCA will able to offer versatile housekeeping and science telemetry system for Zero Pressure Balloons. This concept is modular, use IP protocol for scientific high data rate and mix telemetry systems to perform long duration flight. To respect safety duties, the long duration flight ISBA gondola is modified. New functions are implemented to increase reliability for stratospheric super and zero Pressure balloons flights. "Pointed gondola activity" is also concerned by improvements. After the First Fireball flight, new equipment designs are in progress for future missions. At least, boundary layer balloons performances of science payload and housekeeping system increase with new instrumentation and network telemetry concepts.

  20. Effect of ageing on the passive and active tension and pharmacodynamic characteristics of rat coronary arteries: age-dependent increase in sensitivity to 5-HT and K+.

    PubMed

    Sheykhzade, Majid; Simonsen, Anja Hviid; Boonen, Harrie C M; Outzen, Emilie M; Nyborg, Niels C Berg

    2012-01-01

    The influence of ageing on the passive and active tension and pharmacodynamic characteristics of intramural coronary arteries from 3-month-old and 2-year-old male Wistar rats was investigated using an isometric myograph. The passive vessel wall tension measured in Ca(2+)-free physiological salt solution at L(0) was significantly greater in arteries from old rats (1.46 ± 0.10 Nm(-1), n = 7) than in young rats (1.13 ± 0.13 Nm(-1), n = 6). However, the maximal active tension at L(0) was similar. The spontaneous myogenic tone was increased by age and the vasorelaxation induced by extracellular K(+) was significantly higher in coronary arteries of old rats. The sensitivity (pD(2)) to 5-HT was significantly higher in arteries from old (6.43 ± 0.11, n = 22) than from young rats (6.16 ± 0.08, n = 29). Ketanserin induced a concentration-dependent rightward shift of the 5-HT concentration-response curve in arteries from both young and old rats. The slopes of the regression lines of the Schild plots were not significantly different from unity and the estimated pK(B) values for ketanserin were similar. In conclusion, ageing is associated with changes in passive mechanical characteristics as well as changes in pharmacological properties in rat coronary small arteries.

  1. Tension-Enhanced Hydrogen Evolution Reaction on Vanadium Disulfide Monolayer.

    PubMed

    Pan, Hui

    2016-12-01

    Water electrolysis is an efficient way for hydrogen production. Finding efficient, cheap, and eco-friendly electrocatalysts is essential to the development of this technology. In the work, we present a first-principles study on the effects of tension on the hydrogen evolution reaction of a novel electrocatalyst, vanadium disulfide (VS2) monolayer. Two electrocatalytic processes, individual and collective processes, are investigated. We show that the catalytic ability of VS2 monolayer at higher hydrogen coverage can be efficiently improved by escalating tension. We find that the individual process is easier to occur in a wide range of hydrogen coverage and the collective process is possible at a certain hydrogen coverage under the same tension. The best hydrogen evolution reaction with near-zero Gibbs free energy can be achieved by tuning tension. We further show that the change of catalytic activity with tension and hydrogen coverage is induced by the change of free carrier density around the Fermi level, that is, higher carrier density, better catalytic performance. It is expected that tension can be a simple way to improve the catalytic activity, leading to the design of novel electrocatalysts for efficient hydrogen production from water electrolysis.

  2. Tension-Enhanced Hydrogen Evolution Reaction on Vanadium Disulfide Monolayer

    NASA Astrophysics Data System (ADS)

    Pan, Hui

    2016-02-01

    Water electrolysis is an efficient way for hydrogen production. Finding efficient, cheap, and eco-friendly electrocatalysts is essential to the development of this technology. In the work, we present a first-principles study on the effects of tension on the hydrogen evolution reaction of a novel electrocatalyst, vanadium disulfide (VS2) monolayer. Two electrocatalytic processes, individual and collective processes, are investigated. We show that the catalytic ability of VS2 monolayer at higher hydrogen coverage can be efficiently improved by escalating tension. We find that the individual process is easier to occur in a wide range of hydrogen coverage and the collective process is possible at a certain hydrogen coverage under the same tension. The best hydrogen evolution reaction with near-zero Gibbs free energy can be achieved by tuning tension. We further show that the change of catalytic activity with tension and hydrogen coverage is induced by the change of free carrier density around the Fermi level, that is, higher carrier density, better catalytic performance. It is expected that tension can be a simple way to improve the catalytic activity, leading to the design of novel electrocatalysts for efficient hydrogen production from water electrolysis.

  3. Skin tension related to tension reduction sutures.

    PubMed

    Hwang, Kun; Kim, Han Joon; Kim, Kyung Yong; Han, Seung Ho; Hwang, Se Jin

    2015-01-01

    The aim of this study was to compare the skin tension of several fascial/subcutaneous tensile reduction sutures. Six upper limbs and 8 lower limbs of 4 fresh cadavers were used. At the deltoid area (10 cm below the palpable acromion) and lateral thigh (midpoint from the palpable greater trochanter to the lateral border of the patella), and within a 3 × 6-cm fusiform area of skin, subcutaneous tissue defects were created. At the midpoint of the defect, a no. 5 silk suture was passed through the dermis at a 5-mm margin of the defect, and the defect was approximated. The initial tension to approximate the margins was measured using a tensiometer.The tension needed to approximate skin without any tension reduction suture (S) was 6.5 ± 4.6 N (Newton). The tensions needed to approximate superficial fascia (SF) and deep fascia (DF) were 7.8 ± 3.4 N and 10.3 ± 5.1 N, respectively. The tension needed to approximate the skin after approximating the SF was 4.1 ± 3.4 N. The tension needed to approximate the skin after approximating the DF was 4.9 ± 4.0 N. The tension reduction effect of approximating the SF was 38.8 ± 16.4% (2.4 ± 1.5 N, P = 0.000 [ANOVA, Scheffé]). The tension reduction effect of approximating the DF was 25.2% ± 21.9% (1.5 ± 1.4 N, P = 0.001 [ANOVA, Scheffé]). The reason for this is thought to be that the SF is located closely to the skin unlike the DF. The results of this study might be a basis for tension reduction sutures.

  4. Demonstration of Surface Tension.

    ERIC Educational Resources Information Center

    Rosenthal, Andrew J.

    2001-01-01

    Surface tension is a fundamental obstacle in the spontaneous formation of bubbles, droplets, and crystal nuclei in liquids. Describes a simple overhead projector demonstration that illustrates the power of surface tension that can prevent so many industrial processes. (ASK)

  5. Tension in Cancer

    PubMed Central

    Löffek, Stefanie; Franzke, Claus-Werner; Helfrich, Iris

    2016-01-01

    Integrins represent a large family of cell receptors that mediate adhesion to the extracellular matrix (ECM), thereby modulating a variety of cellular functions that are required for proliferation, migration, malignant conversion and invasiveness. During tumorigenesis the conversion of a tumor cell from sessile, stationary phenotype to an invasive phenotype requires the ability of tumor cells to interact with their environment in order to transduce signals from the ECM into the cells. Hence, there is increasing evidence that changes in the composition, topography and tension of tumor matrix can be sensed by integrin receptors, leading to the regulation of intracellular signalling events which subsequently help to fuel cancer progression. The fact that intracellular signals perceived from integrin ligand binding impact on almost all steps of tumor progression, including tumor cell proliferation, survival, metastatic dissemination and colonization of a metastatic niche, renders integrins as ideal candidates for the development of therapeutic agents. In this review we summarize the role of integrins in cancer with the special focus on cancer therapies and the recent progress that has been made in the understanding of “integrin-induced tension in cancer”. Finally, we conclude with clinical evidence for the role of integrin-mediated mechanotransduction in the development of therapy-resistant tumors. PMID:27854331

  6. Survismeter--type I and II for surface tension, viscosity measurements of liquids for academic, and research and development studies.

    PubMed

    Singh, Man

    2006-06-30

    For centuries surface tension (gamma) and viscosity (eta) data have been measured with individual instruments consuming much time and materials. Thus the two different types of survismeters have been designed and made of borosil glass material for surface tension and viscosity data to rationalize frictional and cohesive forces, respectively. Friccohesity (sigma (sm(-1), second per meter)) is derived from Fric of frictional and cohesity of cohesive forces of the liquid respectively, and denoted by rational coefficient a eta/gamma (sigma). The values of the friccohesity are correlated to the dipole moment of liquids and their plot gives a standard calibration curve along with an equation of the curve with definite values of the coefficients, the friccohesity values are put on the calibration curve to retrieve the dipole moment values. Here, the sigma values for each of dimethylformamide, dimethylsulfoxide and acetronitrile solvents along with their 0.05, 0.10 and 0.20 mol kg(-1) aqueous solutions, respectively, were determined at 293.15K and plotted against their dipole moment values for standard calibration curve. The range of the dipole moment values for calibration curve is pre-decided and the sigma values for homogenous solutions of compositions below their saturation point can be measured with +/-1 x 10(-5)sm(-1).

  7. Culture of human mesenchymal stem cells at low oxygen tension improves growth and genetic stability by activating glycolysis

    PubMed Central

    Estrada, J C; Albo, C; Benguría, A; Dopazo, A; López-Romero, P; Carrera-Quintanar, L; Roche, E; Clemente, E P; Enríquez, J A; Bernad, A; Samper, E

    2012-01-01

    Expansion of human stem cells before cell therapy is typically performed at 20% O2. Growth in these pro-oxidative conditions can lead to oxidative stress and genetic instability. Here, we demonstrate that culture of human mesenchymal stem cells at lower, physiological O2 concentrations significantly increases lifespan, limiting oxidative stress, DNA damage, telomere shortening and chromosomal aberrations. Our gene expression and bioenergetic data strongly suggest that growth at reduced oxygen tensions favors a natural metabolic state of increased glycolysis and reduced oxidative phosphorylation. We propose that this balance is disturbed at 20% O2, resulting in abnormally increased levels of oxidative stress. These observations indicate that bioenergetic pathways are intertwined with the control of lifespan and decisively influence the genetic stability of human primary stem cells. We conclude that stem cells for human therapy should be grown under low oxygen conditions to increase biosafety. PMID:22139129

  8. Aerospace Activities and Language Development

    ERIC Educational Resources Information Center

    Jones, Robert M.; Piper, Martha

    1975-01-01

    Describes how science activities can be used to stimulate language development in the elementary grades. Two aerospace activities are described involving liquid nitrogen and the launching of a weather balloon which integrate aerospace interests into the development of language skills. (BR)

  9. Improvements, testing and development of the ADM-τ sub-grid surface tension model for two-phase LES

    NASA Astrophysics Data System (ADS)

    Aniszewski, Wojciech

    2016-12-01

    In this paper, a specific subgrid term occurring in Large Eddy Simulation (LES) of two-phase flows is investigated. This and other subgrid terms are presented, we subsequently elaborate on the existing models for those and re-formulate the ADM-τ model for sub-grid surface tension previously published by these authors. This paper presents a substantial, conceptual simplification over the original model version, accompanied by a decrease in its computational cost. At the same time, it addresses the issues the original model version faced, e.g. introduces non-isotropic applicability criteria based on resolved interface's principal curvature radii. Additionally, this paper introduces more throughout testing of the ADM-τ, in both simple and complex flows.

  10. Lignification and tension wood.

    PubMed

    Pilate, Gilles; Chabbert, Brigitte; Cathala, Bernard; Yoshinaga, Arata; Leplé, Jean-Charles; Laurans, Françoise; Lapierre, Catherine; Ruel, Katia

    2004-01-01

    Hardwood trees are able to reorient their axes owing to tension wood differentiation. Tension wood is characterised by important ultrastructural modifications, such as the occurrence in a number of species, of an extra secondary wall layer, named gelatinous layer or G-layer, mainly constituted of cellulose microfibrils oriented nearly parallel to the fibre axis. This G-layer appears directly involved in the definition of tension wood mechanical properties. This review gathers the data available in the literature about lignification during tension wood formation. Potential roles for lignin in tension wood formation are inferred from biochemical, anatomical and mechanical studies, from the hypotheses proposed to describe tension wood function and from data coming from new research areas such as functional genomics.

  11. Wall to membrane linkers, stretch activated channels, and the detection of tension, voltage, temperature, auxin, and pH

    NASA Technical Reports Server (NTRS)

    Pickard, B. G.

    1992-01-01

    Introduction. The higher plant is a heterogeneous, mechanically prestressed structure continually subject to shifting forces. When a cell grows in a plant at gravitropic equilibrium, it must create localized maxima of shear in walls of neighboring cells. Such mechanical stress and strain are likely detected in a variety of ways. However, tension-sensitive ion channels are of particular interest because it appears that they are elaborately evolved for sensory function. We hypothesize that 1) the patchy patterns of high shear are focused via wall-to-membrane linkers onto the plasma membrane, where 2) they are translated by mechanosensory cation channels into corresponding patterns of high cytosolic Ca2+, which 3) initiate local enhancement of wall expansion. Further, we hypothesize that the local promotion of enhancement is achieved at least in part by local intensification of auxin transport across the plasma membrane. By implication, when an organ is asymmetrically pressed, rubbed, or bent or when it is displaced in the gravitational field, the net asymmetry of shear stress occurring across the organ would lead to asymmetric redistribution of auxin and corrective asymmetric growth. We shall describe a representative mechanosensitive Ca(2+) -selective cation channel (MCaC) with susceptibilities to xenobiotics implicating it as a force transducer in thigmo- and gravitropism. Then, we shall consider whether a putative wall-to-membrane linker (WML) could be a key feature of the molecular architecture permitting the stress distributed in the wall system to be focused on the channels.

  12. Cytochalasin inhibition of slow tension increase in rat aortic rings.

    PubMed

    Wright, G; Hurn, E

    1994-10-01

    We separated the K(+)-induced contraction of rat aortic rings into its initial (fast) and secondary (slow) components. It was found that temperature sensitivity, K+ depolarization, and Ca2+ dependency could each be utilized to differentiate between these two components of the contractile response. Increasing the passive tension preload of the tissue increased the fast response but had no significant effect on the secondary slow rise in tension. Cytochalasins, which inhibit actin polymerization, reversibly inhibited tension development by rat aortic rings with the effect selectively confined to the slow component of the K(+)-induced contraction. In a similar fashion, cytochalasin was shown to attenuate the slow tension increase caused by phorbol 12,13-dibutyrate. Finally, it was found that low concentrations of the protein kinase C (PKC) inhibitor staurosporine (8 x 10(-9) M) selectively attenuated the slow component of the K(+)-induced contraction. The results suggest that distinctly different mechanisms regulate the initial fast and secondary slow contractile responses induced by elevation of extracellular K+. Both mechanisms are voltage sensitive and use extracellular Ca2+. The fast but not the slow component was altered by changing the passive tension preload in a fashion consistent with a sliding filament mechanism of force development. The specific nature of the slow component is not certain but may involve low-level PKC activity and require the integrity and capability for remodeling of a specific portion of the actin-containing cytoskeleton.

  13. Tendon-Driven Continuum Robot for Endoscopic Surgery: Preclinical Development and Validation of a Tension Propagation Model.

    PubMed

    Kato, Takahisa; Okumura, Ichiro; Song, Sang-Eun; Golby, Alexandra J; Hata, Nobuhiko

    2015-10-01

    In this paper, we present a tendon-driven continuum robot for endoscopic surgery. The robot has two sections for articulation actuated by tendon wires. By actuating the two sections independently, the robot can generate a variety of tip positions while maintaining the tip direction. This feature offers more flexibility in positioning the tip for large viewing angles of up to 180 degrees than does a conventional endoscope. To accurately estimate the tip position at large viewing angles, we employed kinematic mapping with a tension propagation model including friction between the tendon wires and the robot body. In a simulation study using this kinematic-mapping, the two-section robot at a target scale (outer diameter 1.7 mm and length 60 mm) produced a variety of tip positions within 50-mm ranges at the 180°-angle view. In the experimental validation, a 10:1 scale prototype performed three salient postures with different tip positions at the 180°-angle view. The proposed forward kinematic mapping (FKM) predicted the tip position within a tip-to-tip error of 6 mm over the 208-mm articulating length. The tip-to-tip error by FKM was significantly less than the one by conventional piecewise-constant-curvature approximation (PCCA) (FKM: 5.9 ± 2.9 mm vs. PCCA: 23.7 ± 3.6 mm, n=15, P < 0.01).

  14. Tendon-Driven Continuum Robot for Endoscopic Surgery: Preclinical Development and Validation of a Tension Propagation Model

    PubMed Central

    Kato, Takahisa; Okumura, Ichiro; Song, Sang-Eun; Golby, Alexandra J.; Hata, Nobuhiko

    2015-01-01

    In this paper, we present a tendon-driven continuum robot for endoscopic surgery. The robot has two sections for articulation actuated by tendon wires. By actuating the two sections independently, the robot can generate a variety of tip positions while maintaining the tip direction. This feature offers more flexibility in positioning the tip for large viewing angles of up to 180 degrees than does a conventional endoscope. To accurately estimate the tip position at large viewing angles, we employed kinematic mapping with a tension propagation model including friction between the tendon wires and the robot body. In a simulation study using this kinematic-mapping, the two-section robot at a target scale (outer diameter 1.7 mm and length 60 mm) produced a variety of tip positions within 50-mm ranges at the 180°-angle view. In the experimental validation, a 10:1 scale prototype performed three salient postures with different tip positions at the 180°-angle view. The proposed forward kinematic mapping (FKM) predicted the tip position within a tip-to-tip error of 6 mm over the 208-mm articulating length. The tip-to-tip error by FKM was significantly less than the one by conventional piecewise-constant-curvature approximation (PCCA) (FKM: 5.9 ± 2.9 mm vs. PCCA: 23.7 ± 3.6 mm, n=15, P < 0.01). PMID:26380544

  15. Perspectives on Campus Tensions.

    ERIC Educational Resources Information Center

    Nichols, David C., Ed.

    The purpose of this book was to provide background information and insight on campus tensions, and suggest ideas on how to go about reducing these tensions. The papers are divided into 5 parts. Part I, The New Situation, includes papers by Kenneth E. Boulding, William M. Birenbaum, Marcus G. Raskin, and Peter Schrag. Part II, Where the Students…

  16. The effects of inorganic phosphate and arsenate on both passive muscle visco-elasticity and maximum Ca2+ activated tension in chemically skinned rat fast and slow twitch muscle fibres.

    PubMed

    Mutungi, Gabriel

    2003-01-01

    The effects of adding either 25 mM inorganic phosphate (Pi) or its structural analogue arsenate (ASi) on both the maximum Ca2+ activated tension (Po) and passive muscle visco-elasticity (P2 tension) were investigated at 10 degrees C, using segments of single, chemically skinned rat muscle fibres. Whilst the results confirmed some previous findings on the effects of Pi on Po, they also showed that the addition of 25 mM ASi led to a large (approximately 50%) but completely reversible depression of Po in both the fast and slow twitch rat muscle fibres. Moreover, the depression of Po by ASi was greater at low than at high pH values. Examined in the presence of Dextran T-500, the passive tension and sarcomere length responses to a ramp stretch were found to be qualitatively and quantitatively similar to those previously reported in intact rat muscle fibres. Thus, the tension response to a ramp stretch, in the presence and absence of either 25 mM Pi or ASi, consisted of a viscous (P1), a visco-elastic (P2) and an elastic (P3) tension. However, the addition of either 25 mM Pi or ASi led to approximately 15-18% increase in the amplitude of the visco-elastic (P2) tension but had little or no effect on the amplitudes of the other two tension components (viscous, P1 and elastic, P3 tensions). Furthermore, neither compound significantly altered the relaxation rate of the passive muscle visco-elasticity (P2 tension). These results show that Po (arising from cycling cross-bridges) and passive muscle visco-elasticity (P2 tension) are affected differently by both Pi and ASi and suggest that they may not share a common structural basis. The possibility that passive muscle visco-elasticity (P2 tension) arises from the gap-(titin) filament (as suggested previously by Mutungi and Ranatunga, 1996b J Physiol 496: 827-837) and that Pi and ASi increase its amplitude by interacting with the PEVK region of the filament are discussed.

  17. Surface Tension Estimates for Droplet Formation in Slurries with Low Concentrations of Hydrophobic Particles, Polymer Flocculants or Surface-Active Contaminants

    SciTech Connect

    Gauglitz, Phillip A.; Mahoney, Lenna A.; Blanchard, Jeremy; Bamberger, Judith A.

    2011-06-10

    In support of the K-Basin project, Pacific Northwest National Laboratory (PNNL) was requested to evaluate the appropriate surface tension value to use in models predicting the formation of droplets from spray leaks of K-Basin slurries. The specific issue was whether it was more appropriate to use the surface tension of pure water in model predictions for all plausible spray leaks or to use a lower value. The surface tension of K-Basin slurries is potentially affected not only by particles but by low concentrations of nonionic polyacrylamide flocculant and perhaps by contaminants with surfactant properties, which could decrease the surface tension below that of water. A lower surface tension value typically results in smaller droplets being formed with a larger fraction of droplets in the respirable size range, so using the higher surface tension value of pure water is not conservative and thus needs a strong technical basis.

  18. Research and Development. Laboratory Activities.

    ERIC Educational Resources Information Center

    Gallaway, Ann, Ed.

    Research and Development is a laboratory-oriented course that includes the appropriate common essential elements for industrial technology education plus concepts and skills related to research and development. This guide provides teachers of the course with learning activities for secondary students. Introductory materials include an…

  19. Managing tension headaches at home

    MedlinePlus

    Tension-type headache - self-care; Muscle contraction headache - self-care; Headache - benign - self-care; Headache - tension- self-care; Chronic headaches - tension - self-care; Rebound headaches - ...

  20. Model Development and Loads Analysis of an Offshore Wind Turbine on a Tension Leg Platform with a Comparison to Other Floating Turbine Concepts: April 2009

    SciTech Connect

    Matha, D.

    2010-02-01

    This report presents results of the analysis of a 5-MW wind turbine located on a floating offshore tension leg platform (TLP) that was conducted using the fully coupled time-domain aero-hydro-servo-elastic design code FAST with AeroDyn and HydroDyn. The report also provides a description of the development process of the TLP model. The model has been verified via comparisons to frequency-domain calculations. Important differences have been identified between the frequency-domain and time-domain simulations, and have generated implications for the conceptual design process. An extensive loads and stability analysis for ultimate and fatigue loads according to the procedure of the IEC 61400-3 offshore wind turbine design standard was performed with the verified TLP model. This report compares the loads for the wind turbine on the TLP to those of an equivalent land-based turbine. Major instabilities for the TLP are identified and described.

  1. Echinococcal tension pneumothorax

    PubMed Central

    Bakir, Farhan; Al-Omeri, Muayyad M.

    1969-01-01

    Hydatid cyst is rarely mentioned among the causes of pneumothorax in text-books or monographs, especially those written in English. Five examples of tension pneumothorax secondary to ruptured hydatid cyst of the lung are reported: the mechanism of this tension effect and helpful diagnostic points are discussed. We think that surgical correction is the only satisfactory treatment of tension pneumothorax due to ruptured hydatid cyst: surgery is advocated in any suspected cyst as soon as it is discovered so as to avoid any such serious complication. Images PMID:5348321

  2. DNA Looping, Supercoiling and Tension

    NASA Astrophysics Data System (ADS)

    Finzi, Laura

    2007-11-01

    In complex organisms, activation or repression of gene expression by proteins bound to enhancer or silencer elements located several kilobases away from the promoter is a well recognized phenomenon. However, a mechanistic understanding of any of these multiprotein interactions is still incomplete. Part of the difficulty in characterizing long-range interactions is the complexity of the regulatory systems and also an underestimation of the effect of DNA supercoiling and tension. Supercoiling is expected to promote interactions between DNA sites because it winds the DNA into compact plectonemes in which distant DNA segments more frequently draw close. The idea that DNA is also under various levels of tension is becoming more widely accepted. Forces that stretch the double helix in vivo are the electrostatic repulsion among the negatively charged phosphate groups along the DNA backbone, the action of motor enzymes perhaps acting upon a topologically constrained sequence of DNA or chromosome segregation during cell mitosis following DNA replication. Presently, little is known about the tension acting on DNA in vivo, but characterization of how physiological regulatory processes, such as loop formation, depend on DNA tension in vitro will indicate the stretching force regimes likely to exist in vivo. In this light, the well studied CI protein of bacteriophage l, which was recently found to cause a of 3.8 kbp loop in DNA, is an ideal system in which to characterize long-range gene regulation. The large size of the loop lends itself to single-molecule techniques, which allow characterization of the dynamics of CI-mediated l DNA looping under controlled levels of supercoiling and tension. Such experiments are being used to discover the principles of long-range interactions in l and in more complex systems.

  3. A cultural historical activity theory perspective to understand preservice science teachers' reflections on and tensions during a microteaching experience

    NASA Astrophysics Data System (ADS)

    Sezen-Barrie, Asli; Tran, Minh-Dan; McDonald, Scott P.; Kelly, Gregory J.

    2014-09-01

    This study draws from cultural historical activity theory (CHAT) to analyze preservice teachers' reflections on a microteaching activity. Microteaching activities involved preservice educators teaching middle school students from local schools. The study was conducted with 23 preservice teachers enrolled in a large university's teacher education program. During this secondary science teaching methods course, every pair of preservice teachers engaged in 20 minute microteaching activity with 3-5 middle school students. The microteaching was videotaped, and the teachers subsequently provided voice-over reflections on a second audio track. Transcriptions of the microteaching events were analyzed through the formation of event maps showing the phases of activity and the organizational sequence of actions. Event maps were used to investigate the focus of preservice teachers' reflections. The results showed that while learning from their microteaching, preservice teachers focused primarily on the mediating artifacts and gave least attention to the larger teaching community surrounding these activities. Use of CHAT helped to identify challenges in different elements of the microteaching activity. The study contributes to how reflective practice can be enhanced through attention to the social and cultural dimensions of the teaching.

  4. Variations in Repetition Duration and Repetition Numbers Influence Muscular Activation and Blood Lactate Response in Protocols Equalized by Time Under Tension.

    PubMed

    Lacerda, Lucas T; Martins-Costa, Hugo C; Diniz, Rodrigo C R; Lima, Fernando V; Andrade, André G P; Tourino, Frank D; Bemben, Michael G; Chagas, Mauro H

    2016-01-01

    The aim of this study was to investigate the impact of protocols equalized by the time under tension (TUT) but composed of different repetition durations and repetitions numbers on muscle activation and blood lactate concentration. Twenty-two males with previous experience in resistance training performed 2 training protocols (A and B) with the Smith machine bench press exercise, both with 3 sets, 3 minutes' rest, and 60% of 1 repetition maximum (1RM). Protocol A consisted of 6 repetitions with a 6-second repetition duration for each repetition, whereas in Protocol B the subjects performed 12 repetitions with a 3-second repetition duration for each repetition. Muscular activation was measured in the anterior deltoid, pectoralis major, and triceps brachii muscles while performing the 2 protocols, and the normalized root mean square of the electromyographic signal (EMGRMS) was calculated for each set. Blood lactate concentrations were measured during and until 12 minutes after the completion of each protocol. The results showed that the EMGRMS of all muscles increased during the sets and was higher in Protocol B when compared with Protocol A. Likewise, blood lactate concentrations also increased throughout the sets and were higher in Protocol B both during and after the completion of each training session. The data obtained in this study show that training protocols conducted with the same TUT, but with different configurations, produce distinct neuromuscular and metabolic responses so that performing higher repetition numbers with shorter repetition durations might be a more appropriate strategy to increase muscle activation and blood lactate concentration.

  5. Handheld magnetic sensor for measurement of tension

    NASA Astrophysics Data System (ADS)

    Singal, K.; Rajamani, R.

    2012-04-01

    This letter develops an analytical formulation for measurement of tension in a string using a handheld sensor. By gently pushing the sensor against the string, the tension in the string can be obtained. An experimental sensor prototype is constructed to verify the analytical formulation. The centimeter-sized prototype utilizes three moving pistons and magnetic field based measurements of their positions. Experimental data show that the sensor can accurately measure tension on a bench top rig. The developed sensor could be useful in a variety of orthopedic surgical procedures, including knee replacement, hip replacement, ligament repair, shoulder stabilization, and tendon repair.

  6. A miniature tension sensor to measure surgical suture tension of deformable musculoskeletal tissues during joint motion.

    PubMed

    Kiriyama, Yoshimori; Matsumoto, Hideo; Toyama, Yoshiaki; Nagura, Takeo

    2014-02-01

    The aim of this study was to develop a new suture tension sensor for musculoskeletal soft tissue that shows deformation or movements. The suture tension sensor was 10 mm in size, which was small enough to avoid conflicting with the adjacent sensor. Furthermore, the sensor had good linearity up to a tension of 50 N, which is equivalent to the breaking strength of a size 1 absorbable suture defined by the United States Pharmacopeia. The design and mechanism were analyzed using a finite element model prior to developing the actual sensor. Based on the analysis, adequate material was selected, and the output linearity was confirmed and compared with the simulated result. To evaluate practical application, the incision of the skin and capsule were sutured during simulated total knee arthroplasty. When conventional surgery and minimally invasive surgery were performed, suture tensions were compared. In minimally invasive surgery, the distal portion of the knee was dissected, and the proximal portion of the knee was dissected additionally in conventional surgery. In the skin suturing, the maximum tension was 4.4 N, and this tension was independent of the sensor location. In contrast, the sensor suturing the capsule in the distal portion had a tension of 4.4 N in minimally invasive surgery, while the proximal sensor had a tension of 44 N in conventional surgery. The suture tensions increased nonlinearly and were dependent on the knee flexion angle. Furthermore, the tension changes showed hysteresis. This miniature tension sensor may help establish the optimal suturing method with adequate tension to ensure wound healing and early recovery.

  7. Evaluation of different culture systems with low oxygen tension on the development, quality and oxidative stress-related genes of bovine embryos produced in vitro.

    PubMed

    Arias, Maria Elena; Sanchez, Raul; Felmer, Ricardo

    2012-08-01

    The present study was conducted to assess the development, quality and gene expression profile of oxidative stress-related genes of bovine embryos cultured in different culture systems with low oxygen tension (5% CO2, 5% O2 and 90% N2). The systems assessed included: (1) an incubator chamber; (2) a plastic bag; and (3) a foil bag. The choice of culture system had no effect on cleavage rate at 72 h. However, significant differences (P < 0.01) were observed in the rate of blastocysts registered at day 7 (29.8, 20.2 and 12.7% for incubator chamber, plastic bag and foil bag, respectively). Total number of cells did not differ between systems, although the proportion of ICM:total cells was affected particularly in the plastic bag (19.5%), compared with the incubator chamber (31.4%). In addition, significant differences were found in the apoptotic:total cell ratio (3.3, 6.5 and 8.8% for the incubator chamber, plastic bag and foil bag, respectively), with apoptotic nuclei localised mainly in the ICM compartment of the embryo. The amount of reactive oxygen species was also different between culture systems and this effect was correlated with a higher expression of SOD2, GSS and GPX1 genes in embryos cultured in the gassed bags as compared with embryos cultured in the incubator chamber. In conclusion, these results give evidence that, under low oxygen tension, the incubator chamber is more efficient and generates higher number of, and better quality, embryos than gassed bag systems evaluated here and this effect was probably due to an increased level of reactive oxygen species in the gassed bags, which upregulates the expression of some antioxidant enzymes to compensate for hyperoxia conditions.

  8. Fluoride glass: Crystallization, surface tension

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.

    1988-01-01

    Fluoride glass was levitated acoustically in the ACES apparatus on STS-11, and the recovered sample had a different microstructure from samples cooled in a container. Further experiments on levitated samples of fluoride glass are proposed. These include nucleation, crystallization, melting observations, measurement of surface tension of molten glass, and observation of bubbles in the glass. Ground experiments are required on sample preparation, outgassing, and surface reactions. The results should help in the development and evaluation of containerless processing, especially of glass, in the development of a contaminent-free method of measuring surface tensions of melts, in extending knowledge of gas and bubble behavior in fluoride glasses, and in increasing insight into the processing and properties of fluoride glasses.

  9. Length-tension relationships of small arteries, veins, and lymphatics from the rat mesenteric microcirculation.

    PubMed

    Zhang, Rong-Zhen; Gashev, Anatoliy A; Zawieja, David C; Davis, Michael J

    2007-04-01

    The passive and active length-tension relationships of isolated rat mesenteric lymphatics ( approximately 150 microm ID), and adjacent small arteries ( approximately 240 microm) and veins ( approximately 275 microm) were compared under isometric conditions using a wire myograph. About 60% of the lymphatic vessels developed spontaneous contractions in physiological saline solution at nominal preload. To maximally activate smooth muscle, 145 mM K(+) + 5 x 10(-5) M norepinephrine was used for arteries, and 145 mM K(+) + 1 x 10(-6) M substance P was used for lymphatics and veins. In response, arteries exhibited monotonic force development to a plateau level, whereas lymphatics and veins showed biphasic force development, consisting of a transient force peak followed by partial relaxation to a plateau over approximately 5 min. The passive and the active length-tension curves were similar in shape among all three vessels. However, the maximal active tension of arteries (3.4 +/- 0.42 mN/mm) was significantly greater than peak active tension (0.59 +/- 0.04 mN/mm) or plateau tension (0.20 +/- 0.04 mN/mm) in small veins and greater than peak active tension (0.34 +/- 0.02 mN/mm) or plateau tension (0.21 +/- 0.02 mN/mm) in lymphatics. Maximal active medial wall stress was similar between lymphatics and veins but was approximately fivefold higher in small arteries. For lymphatics, the pressure calculated from the optimal preload was significantly higher than that found previously in isobaric studies of isolated lymphatics, suggesting the capacity to operate at higher than normal pressures for increased responsiveness. Our results represent the first mechanical comparisons of arterial, venous, and lymphatic vessels in the same vasculature.

  10. Robust Tensioned Kevlar Suspension Design

    NASA Technical Reports Server (NTRS)

    Young, Joseph B.; Naylor, Bret J.; Holmes, Warren A.

    2012-01-01

    One common but challenging problem in cryogenic engineering is to produce a mount that has excellent thermal isolation but is also rigid. Such mounts can be achieved by suspending the load from a network of fibers or strings held in tension. Kevlar fibers are often used for this purpose owing to their high strength and low thermal conductivity. A suite of compact design elements has been developed to improve the reliability of suspension systems made of Kevlar.

  11. Competing effects of viscosity and surface-tension depression on the hygroscopicity and CCN activity of laboratory surrogates for oligomers in atmospheric aerosol

    NASA Astrophysics Data System (ADS)

    Hodas, N.; Zuend, A.; Shiraiwa, M.; Flagan, R. C.; Seinfeld, J.; Schilling, K.; Berkemeier, T.

    2015-12-01

    The presence of oligomers in biomass burning aerosol, as well as secondary organic aerosol derived from other sources, influences particle viscosity and can introduce kinetic limitations to water uptake. This, in turn, impacts aerosol optical properties and the efficiency with which these particles serve as cloud condensation nuclei (CCN). To explore the influence of organic-component viscosity on aerosol hygroscopicity, the water-uptake behavior of aerosol systems comprised of polyethylene glycol (PEG) and mixtures of PEG and ammonium sulfate (AS) was measured under sub- and supersaturated relative humidity (RH) conditions. Experiments were conducted with systems containing PEG with average molecular weights ranging from 200 to 10,000 g/mol, corresponding to a range in viscosity of 0.004 - 4.5 Pa s under dry conditions. While evidence suggests that viscous aerosol components can suppress water uptake at RH < 90%, under supersaturated conditions (with respect to RH), an increase in CCN activity with increasing PEG molecular weight was observed. We attribute this to an increase in the efficiency with which PEG serves as a surfactant with increasing molecular weight. This effect is most pronounced for PEG-AS mixtures and, in fact, a modest increase in CCN activity is observed for the PEG 10,000-AS mixture as compared to pure AS, as evidenced by a 4% reduction in critical activation diameter. Experimental results are compared with calculations of hygroscopic growth at thermodynamic equilibrium using the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients model and the potential influence of kinetic limitations to observed water uptake is further explored with the Kinetic Multi-Layer Model of Gas-Particle Interactions. Results suggest the competing effects of organic-component viscosity and surface-tension depression may lead to RH-dependent differences in hygroscopicity for oligomers and other surface-active compounds present in atmospheric

  12. Managing the right tension.

    PubMed

    Dodd, Dominic; Favaro, Ken

    2006-12-01

    Of all the competing objectives every company faces, three pairs stand out: profitability versus growth, the short term versus the long term, and the whole organization versus the units. In each case, progress on one front usually comes at the expense of progress on the other. The authors researched the performance of more than 1000 companies worldwide over the past two decades and found that most struggle to succeed across the three tensions. From 1983 to 2003, for example, only 32% of these companies more often than not achieved positive profitability and revenue growth at the same time. The problem, the authors discovered, is not so much that managers don't recognize the tensions--those are all too familiar to anyone who has ever run a business. Rather, it is that managers frequently don't focus on the tension that matters most to their company. Even when they do identify the right tension, they usually make the mistake of prioritizing a "lead" objective within it-for example, profitability over growth. As a result, companies often end up moving first in this direction, then in that, and then back again, never quite resolving the tension. The companies that performed best adopted a very different approach. Instead of setting a lead objective, they looked at how best to strengthen what the two sides of each tension have in common: For profitability and growth,the common bond is customer benefit; for the short term and the long, it is sustainable earnings; and for the whole and its parts, it is particular organizational resources and capabilities. The authors describe how companies can select the right tension, what traps they may fall into when they focus on one side over the other, and how to escape these traps by managing to the bonds between objectives.

  13. Factors influencing the ascending limb of the sarcomere length-tension relationship in rabbit skinned muscle fibres.

    PubMed Central

    Allen, J D; Moss, R L

    1987-01-01

    1. The length dependence of Ca2+-activated tension within the ascending limb of the length-tension relationship, corresponding to sarcomere lengths below about 2.25 micron, was investigated in skinned fibres from rabbit psoas muscle. At high [Ca2+] a shallow phase and then a steep phase of tension decline were observed as sarcomere length was reduced, while at low [Ca2+] tension decreased monotonically with decreases in sarcomere length. The sarcomere length at which the ascending limb intersected zero tension was greater for lower concentrations of Ca2+. 2. The length tension relationship from maximally activated fibres changed when filament lattice spacing was reduced by osmotic compression. Relationships obtained in the presence of 5% (w/v) dextran T500 more distinctly demonstrated both the shallow and steep portions of the ascending limb than did relationships from untreated fibres. 3. As striation spacing was decreased a progressive decline in the Ca2+ sensitivity of tension development was observed. Tension-pCa relationships from both control and dextran-treated fibres underwent a rightward shift (i.e. to a higher [Ca2+]) by 0.23 pCa units as sarcomere length was reduced between 2.46 and 1.54 microns. 4. Fibre stiffness was studied by applying a 3.3 kHz sinusoidal length change at one end of the fibre and measuring the resultant tension change. At submaximal activation (pCa 5.8), stiffness increased relative to tension as sarcomere length was decreased below approximately 2.4 microns, suggesting that there is an activation-related internal load at low [Ca2+]. At maximal activation, a significant increase in this ratio occurred only at sarcomere lengths less than approximately 1.8 microns, and presumably involved collision of the thick filaments with the Z-lines. 5. Length-dependent changes in the Ca2+ sensitivity of tension development do not appear to be the result of shortening-induced dissociation of Ca2+ from troponin-C, the Ca2+ binding subunit of

  14. Surface Tension Microscopy

    NASA Astrophysics Data System (ADS)

    Neumann, Burkhard; Engel, Horst; Schleifenbaum, Bernd

    1989-12-01

    A new microscopic technique will be presented for imaging surface topography and the locally varying surface tension of the object. With this technique it is possible to image the locally varying chemical composition of the specimen surface on a microscopic scale because the surface tension depends on the chemical composition. The imaging technique can be described as follows: By a simple preparation technique a thin (thickness several microns) liquid layer (e.g. immersion oil), is placed on the surface of the specimen. The resulting surface tension forces the boundary of the liquid layer to move. As the surface tension is a function of the location the boundary is modulated according to the magnitude of the surface tension at each place. Thus registering the shape of the moving boundary of the liquid layer at equidistant time intervals yields information on the specimen surface. The shape of the moving boundary is detected by a light microscope with differential interference contrast in combination with an image analysis system suited for real-time processing of image sequences in a threshold detection mode.

  15. Developing Photo Activated Localization Microscopy

    NASA Astrophysics Data System (ADS)

    Hess, Harald

    2015-03-01

    Photo Activated Localization Microscopy, PALM, acquires super-resolution images by activating a subset of activatable fluorescent labels and estimating the center of the each molecular label to sub-diffractive accuracy. When this process is repeated thousands of times for different subsets of molecules, then an image can be rendered from all the center coordinates of the molecules. I will describe the circuitous story of its development that began with another super-resolution technique, NSOM, developed by my colleague Eric Betzig, who imaged single molecules at room temperature, and later we spectrally resolved individual luminescent centers of quantum wells. These two observations inspired a generalized path to localization microscopy, but that path was abandoned because no really useful fluorescent labels were available. After a decade of nonacademic industrial pursuits and the subsequent freedom of unemployment, we came across a class of genetically expressible fluorescent proteins that were switchable or convertible that enabled the concept to be implemented and be biologically promising. The past ten years have been very active with many groups exploring applications and enhancements of this concept. Demonstrating significant biological relevance will be the metric if its success.

  16. [Treatment of tension headache].

    PubMed

    Schoenen, J

    2000-01-01

    The scientific basis of tension- type headache suffers from the lack of precise pathophysiological knowledge and the heterogenecity of this disorder. Treatment of acute tension-type headache episodes is more effective with an NSAIDs (ibuprofen 400-800mg, naproxen 550-825mg, ketoprofen 50-75mg) than with aspirin or paracetamol. Caffein containing preparations of NSAIDs are slightly superior, but should not be taken frequently to avoid headache chronification. For chronic tension-type headache, relaxation therapies with EMG biofeedback and tricyclics have about the same efficacy rate of 40-50p.100. Physical therapy and acupuncture are in general less effective. There is thus clearly a need for better strategies, e.g. combination of available therapies and novel approaches.

  17. Surface Tension of Spacetime

    NASA Astrophysics Data System (ADS)

    Perko, Howard

    2017-01-01

    Concepts from physical chemistry and more specifically surface tension are introduced to spacetime. Lagrangian equations of motion for membranes of curved spacetime manifold are derived. The equations of motion in spatial directions are dispersion equations and can be rearranged to Schrodinger's equation where Plank's constant is related to membrane elastic modulus. The equation of motion in the time-direction has two immediately recognizable solutions: electromagnetic waves and corpuscles. The corpuscular membrane solution can assume different genus depending on quantized amounts of surface energy. A metric tensor that relates empty flat spacetime to energetic curved spacetime is found that satisfies general relativity. Application of the surface tension to quantum electrodynamics and implications for quantum chromodynamics are discussed. Although much work remains, it is suggested that spacetime surface tension may provide a classical explanation that combines general relativity with field theories in quantum mechanics and atomic particle physics.

  18. Tension solar mirror

    SciTech Connect

    Russo, W.P.

    1986-09-02

    A solar collector is described comprising a central tower having a solar receiver thereon; tension towers positioned concentrically about the central tower;a rigid inner ring disposed about the central tower and sized to permit vertical movement relative to the central tower; cables extending between the inner ring and the tops of each of the tension towers; and a reflectively-coated sheet of flexible material attached to the upper surface of the cables; whereby the action of gravity on the cables and the sheet form a concave reflector for focusing solar energy onto the solar receiver.

  19. Development and Experimental Validation of Morphology Predictive Model for Compatibilized Ternary Polymer Blends I. Effect of Interfacial Tension

    NASA Astrophysics Data System (ADS)

    Shokoohi, Shirin; Naderi, Ghasem

    2016-01-01

    To evaluate the prediction reliability of conventional morphology predicting models, polypropylene (PP)/polyamide6 (PA6)/ethylene propylene diene monomer (EPDM) (70/15/15) ternary polymer blends compatibilized with Maleic-anhydride grafted EPDM (EPDM-g-MA) were prepared through melt blending using a twin screw extruder (TSE). Different EPDM/EPDM-g-MA ratios i.e. 100/0, 75/25, 50/50, 25/75 and 0/100 were used to prepare the ternery blend PP/(EPDM-g-MA + EPDM)/PA6 samples. The effects of compatibilizer content on the microstructures and consequently mechanical properties of prepared ternary blends were studied. Direct microstructural observations were compared to the predictions of conventional phenomenological models including spreading coefficient, minimum relative free energy, and dynamic interfacial energy. A comparison depicted the relative inaccuracy of the existing models in predicting the morphology of the present ternary system due to the ignorance of some effective parameters and/or discomfit of model assumptions. A novel predictive model was developed considering parameters ignored in conventional models. A thorough investigation of the model's validation results showed a reasonable agreement between model predictions and direct microstructural observations.

  20. Development of enhanced ultrasonic imaging for in-situ inspection of a tension-stressed threaded fastener

    NASA Astrophysics Data System (ADS)

    Good, Morris S.; Harris, Robert V., Jr.; Skorpik, James R.; Pardini, Allan F.; Smith, Christopher M.; Bowey, Robert E.; Diaz, Aaron A.; Burghard, Brion J.; Judd, Kayte M.; Adamson, Justus D.

    2000-06-01

    A laboratory system was developed that utilized an ultrasonic pulse-echo technique to detect very small cracks emanating from the thread root of a tensile-stressed fastener. Primary benefits were (1) the ability to inspect the fastener without its removal from the structure, (2) much improved detection sensitivity to small cracks, and (3) easy interpretation of data. The fastener of interest had threads with nominal inner and outer diameters of 1.8 cm (0.73 in.) and 2.2 cm (0.86 in.), respectively, and a thread pitch of 3.1 threads per centimeter (8.0 threads per in.). A plastic washer was placed over the fastener nut to shield the nut from ultrasound and thereby eliminate spurious signals. B-scan images provided feedback to align the ultrasonic scanner and fastener for optimal detection sensitivity. A tone-burst pulser-receiver controlled excitation frequency and bandwidth to maintain focal properties, minimize backscatter noise from the base material, and increase penetration into the coarse-grained Inconel. A custom ultrasonic transducer was used to optimize the focal properties over the inspection zone of 2.3 cm to 3.3 cm (0.9 in. to 1.3 in.) from the threaded end of the fastener. A calibration part with four 1.0-mm (0.040-in.) deep notches spanning the length of the inspection zone was used to calibrate distance-amplitude correction and system sensitivity. Custom B-scan and C-scan views were used to present data to the inspector and optimize the signal-to-noise ratio. A direct comparison was made between ultrasonic and destructive test images. Details of system hardware, data- acquisition procedure, analysis, and plans for a portable hand-held system for field inspection are provided.

  1. The development of Tobacco Harm Prevention Law in Vietnam: stakeholder tensions over tobacco control legislation in a state owned industry

    PubMed Central

    2011-01-01

    Background Building on its National Tobacco Control Policy initiated in 2000, Vietnam is currently considering introducing a comprehensive law to strengthen the implementation of tobacco control policy. This study analyses the positions of key stakeholders in the development of tobacco control legislation in the context of a largely state-owned industry, and discusses their implications for the policy process. Methods Several qualitative methods were employed for the study including: literature review and documentary analysis; key informant interview; focus groups discussion; and key stakeholders survey. Findings The Ministry of Health, Ministry of Trade and Industry, and Ministry of Finance are key players in the tobacco control policy and legislation, representing competing bureaucratic interests over health, macro-economy and revenue. High-ranking officials, including the Communist Party and National Assembly members, take a rather relaxed position reflecting the low political stakes placed on tobacco issues. The state-owned tobacco industry is regarded as an important contributor to the government revenue and gross domestic product, and the relative weight on health and socioeconomic issues placed by stakeholders determine their positions on tobacco control. Overall, short-term economic interests have more immediate influence in setting policy directions, with the consequences of health gains perceived as relegated to a distant future. This was reflected in the position of tobacco control advocates, including MOH, that presented with reluctance in insisting on some tobacco control strategies revealing a mixture attitude of concessions to the socioeconomic uncertainties and a sense of bargaining to win the strategies that are more likely to be accepted. Conclusion The state-ownership of tobacco industry poses a major paradox within the government that benefits from manufacturing of tobacco products and is also responsible for controlling tobacco consumption. The

  2. Transient tension changes initiated by laser temperature jumps in rabbit psoas muscle fibres.

    PubMed Central

    Goldman, Y E; McCray, J A; Ranatunga, K W

    1987-01-01

    1. A technique was developed to generate 2-8 degrees C step temperature perturbations (T-jumps) in single muscle fibres to study the thermodynamics of muscle contraction. A solid-state pulsed holmium laser emitting at 2.065 microns heated the fibre and surrounding solution in approximately 150 mus. The signal from a 100 microns thermocouple fed back to a heating wire maintained the elevated temperature after the laser pulse. 2. Tension of glycerol-extracted muscle fibres from rabbit psoas muscle did not change significantly following T-jumps when the fibre was relaxed. 3. In rigor, tension decreased abruptly on heating indicating normal (not rubber-like) thermoelasticity. The thermoelastic coefficient (negative ratio of relative length change to relative temperature change) of the fibre was estimated to be -0.021 at sarcomere lengths of 2.5-2.8 microns. Rigor tension was constant after the temperature step and returned to the original value on recooling. 4. In maximal Ca2+ activation, tension transients initiated by T-jumps had several phases. An immediate tension decrease suggests that thermoelasticity during contraction is similar to that in rigor. Active tension then recovered to the value before the T-jump with an apparent rate constant of approximately 400 s-1 (at 10-20 degrees C). This rate constant did not have an appreciable dependence on the final temperature. Finally, tension increased exponentially to a new higher level with a rate constant of approximately 20 s-1 at 20 degrees C. This rate constant increased with temperature with a Q10 of 1.4. 5. At submaximal Ca2+ activation the tension rise was followed by a decay to below the value before the T-jump. This decline was expected from the temperature dependence of steady pCa-tension curves. The final tension decline occurred on the 1-5 s time scale. 6. The value and amplitude dependence of the rate constant for the quick recovery following T-jumps were similar to those of the quick recovery following

  3. A local difference in Hedgehog signal transduction increases mechanical cell bond tension and biases cell intercalations along the Drosophila anteroposterior compartment boundary.

    PubMed

    Rudolf, Katrin; Umetsu, Daiki; Aliee, Maryam; Sui, Liyuan; Jülicher, Frank; Dahmann, Christian

    2015-11-15

    Tissue organization requires the interplay between biochemical signaling and cellular force generation. The formation of straight boundaries separating cells with different fates into compartments is important for growth and patterning during tissue development. In the developing Drosophila wing disc, maintenance of the straight anteroposterior (AP) compartment boundary involves a local increase in mechanical tension at cell bonds along the boundary. The biochemical signals that regulate mechanical tension along the AP boundary, however, remain unknown. Here, we show that a local difference in Hedgehog signal transduction activity between anterior and posterior cells is necessary and sufficient to increase mechanical tension along the AP boundary. This difference in Hedgehog signal transduction is also required to bias cell rearrangements during cell intercalations to keep the characteristic straight shape of the AP boundary. Moreover, severing cell bonds along the AP boundary does not reduce tension at neighboring bonds, implying that active mechanical tension is upregulated, cell bond by cell bond. Finally, differences in the expression of the homeodomain-containing protein Engrailed also contribute to the straight shape of the AP boundary, independently of Hedgehog signal transduction and without modulating cell bond tension. Our data reveal a novel link between local differences in Hedgehog signal transduction and a local increase in active mechanical tension of cell bonds that biases junctional rearrangements. The large-scale shape of the AP boundary thus emerges from biochemical signals inducing patterns of active tension on cell bonds.

  4. Dynamic Tension Spectroscopy and Strength of Biomembranes

    PubMed Central

    Evans, Evan; Heinrich, Volkmar; Ludwig, Florian; Rawicz, Wieslawa

    2003-01-01

    Rupturing fluid membrane vesicles with a steady ramp of micropipette suction produces a distribution of breakage tensions governed by the kinetic process of membrane failure. When plotted as a function of log(tension loading rate), the locations of distribution peaks define a dynamic tension spectrum with distinct regimes that reflect passage of prominent energy barriers along the kinetic pathway. Using tests on five types of giant phosphatidylcholine lipid vesicles over loading rates(tension/time) from 0.01–100 mN/m/s, we show that the kinetic process of membrane breakage can be modeled by a causal sequence of two thermally-activated transitions. At fast loading rates, a steep linear regime appears in each spectrum which implies that membrane failure starts with nucleation of a rare precursor defect. The slope and projected intercept of this regime are set by defect size and frequency of spontaneous formation, respectively. But at slow loading rates, each spectrum crosses over to a shallow-curved regime where rupture tension changes weakly with rate. This regime is predicted by the classical cavitation theory for opening an unstable hole in a two-dimensional film within the lifetime of the defect state. Under slow loading, membrane edge energy and the frequency scale for thermal fluctuations in hole size are the principal factors that govern the level of tension at failure. To critically test the model and obtain the parameters governing the rates of transition under stress, distributions of rupture tension were computed and matched to the measured histograms through solution of the kinetic master (Markov) equations for defect formation and annihilation or evolution to an unstable hole under a ramp of tension. As key predictors of membrane strength, the results for spontaneous frequencies of defect formation and hole edge energies were found to correlate with membrane thicknesses and elastic bending moduli, respectively. PMID:14507698

  5. Wide and high resolution tension measurement using FRET in embryo

    PubMed Central

    Yamashita, Satoshi; Tsuboi, Takashi; Ishinabe, Nanako; Kitaguchi, Tetsuya; Michiue, Tatsuo

    2016-01-01

    During embryonic development, physical force plays an important role in morphogenesis and differentiation. Stretch sensitive fluorescence resonance energy transfer (FRET) has the potential to provide non-invasive tension measurements inside living tissue. In this study, we introduced a FRET-based actinin tension sensor into Xenopus laevis embryos and demonstrated that this sensor captures variation of tension across differentiating ectoderm. The actinin tension sensor, containing mCherry and EGFP connected by spider silk protein, was validated in human embryonic kidney (HEK) cells and embryos. It co-localized with actin filaments and changed FRET efficiencies in response to actin filament destruction, myosin deactivation, and osmotic perturbation. Time-lapse FRET analysis showed that the prospective neural ectoderm bears higher tension than the epidermal ectoderm during gastrulation and neurulation, and cells morphogenetic behavior correlated with the tension difference. These data confirmed that the sensor enables us to measure tension across tissues concurrently and with high resolution. PMID:27335157

  6. Surface tension of spherical drops from surface of tension

    SciTech Connect

    Homman, A.-A.; Bourasseau, E.; Malfreyt, P.; Strafella, L.; Ghoufi, A.

    2014-01-21

    The determination of surface tension of curved interfaces is a topic that raised many controversies during the last century. Explicit liquid-vapor interface modelling (ELVI) was unable up to now to reproduce interfacial behaviors in drops due to ambiguities in the mechanical definition of the surface tension. In this work, we propose a thermodynamic approach based on the location of surface of tension and its use in the Laplace equation to extract the surface tension of spherical interfaces from ELVI modelling.

  7. Fluctuations in intracellular calcium concentration and their effect on tonic tension in canine cardiac Purkinje fibres.

    PubMed Central

    Kort, A A; Lakatta, E G; Marban, E; Stern, M D; Wier, W G

    1985-01-01

    Ca2+-activated aequorin luminescence and tension were measured in dog Purkinje fibres during twitches and during the increase in resting force produced by exposure of the fibres to a low-Na+ solution after 3 min without external K+. Over the restricted range which could be examined, the relation between tension and 'mean' aequorin luminescence (luminescence filtered at 0.2 Hz) was approximately linear during the development and maintenance of contracture. For a given level of force, the mean aequorin luminescence during contracture was up to 20 times greater than the peak luminescence during the twitch. Noise analysis of aequorin luminescence and tension during contracture indicated the presence of periodic fluctuations, with a predominant frequency in the range 1-4 Hz. Ryanodine (1 microM) or caffeine (10 mM) abolished the fluctuations in luminescence and tension and made the relation between tension and mean aequorin luminescence much steeper. A mathematical model, the key feature of which is periodicity in the asynchronous occurrence of spatially localized regions of relatively high [Ca2+], reproduces the experimental data derived from contractures. From the model analysis, we infer that tonic tension is produced by recruitment of increasing numbers of regions of high [Ca2+], rather than by homogeneous graded activation. These results indicate that during contracture or 'tonic tension', intracellular [Ca2+] is not at steady state, but rather undergoes large, asynchronous spatio-temporal fluctuations. Thus the assumptions that intracellular [Ca2+] is at steady state or homogeneous during tonic tension are not valid. PMID:4057100

  8. Tension-type headache.

    PubMed

    Diamond, S

    1999-01-01

    Tension-type headaches, the most prevalent form of headache, are differentiated as being either episodic or chronic. The episodic form is a physiologic response to stress, anxiety, depression, emotional conflicts, fatigue, or repressed hostility. Treatment focuses on the use of over-the-counter or prescribed simple analgesics for pain relief. Successful treatment of the chronic form depends on recognition of depression or persistent anxiety states. Primary care physicians can effectively manage most of these patients with nonhabituating anxiolytic or antidepressant medications; however, referrals for psychotherapy may be required in some cases. When tension-type headaches occur in children and adolescents, the physician must explore the patient's family and social relationships as well as school performance. In addition to nonhabituating drug therapies, family counseling and biofeedback may be helpful. In coexisting migraine and tension-type headaches, nonhabituating analgesics may be used for the relief of acute pain; the use of ergotamine and triptans should be restricted to relief of the hard or sick headache. Tricyclic antidepressants or monoamine oxidase inhibitors are the gold standards for prophylaxis, although the selective serotonin reuptake inhibitors may be indicated in less severe cases. Several forms of biofeedback have also proved effective. Nonetheless, some patients with this form of headache may require psychiatric treatment for severe depression.

  9. Surface tension and microgravity

    NASA Astrophysics Data System (ADS)

    Meseguer, J.; Sanz-Andrés, A.; Pérez-Grande, I.; Pindado, S.; Franchini, S.; Alonso, G.

    2014-09-01

    The behaviour of confined liquids on board an orbiting spacecraft is mainly driven by surface tension phenomena, which cause an apparently anomalous response of the liquid when compared with the behaviour that can be observed on an Earth laboratory provided that the amount of liquid is high enough. The reason is that in an orbiting spacecraft the different inertial forces acting on the bulk of the liquid are almost zero, causing thus capillary forces to be the dominant ones. Of course, since gravity forces are proportional to the liquid volume, whereas surface tension forces are proportional to the liquid surface, there are situations on Earth where capillarity can be the dominant effect, as it happens when very small volume liquid samples are considered. However, work with small size samples may require the use of sophisticated optical devices. Leaving aside the neutral buoyancy technique, a way of handling large liquid interfaces is by using drop towers, where the sample falls subjected to the action of Earth’s gravity. This approach is suitable when the characteristic time of the problem under consideration is much smaller than the drop time. In this work the transformation of an out-of-use chimney into a drop tower is presented. Because of the miniaturization, hardiness and low cost of current electronic devices, a drop tower can be used as an inexpensive tool for undergraduate students to experimentally analyse a large variety of surface tension driven phenomena.

  10. Listening to diverse community voices: the tensions of responding to community expectations in developing a male circumcision program for HIV prevention in Papua New Guinea

    PubMed Central

    2013-01-01

    Background The success of health programs is influenced not only by their acceptability but also their ability to meet and respond to community expectations of service delivery. The World Health Organization (WHO) and the Joint United Nations Programme on HIV/AIDS (UNAIDS) have recommended medical male circumcision (MC) as an essential component of comprehensive HIV prevention programs in high burden settings. This study investigated community-level perceptions of MC for HIV prevention in Papua New Guinea (PNG), a setting where diverse traditional and contemporary forms of penile foreskin cutting practices have been described. Methods A multi-method qualitative study was undertaken in four provinces in two stages from 2009 to 2011. A total of 82 in-depth interviews, and 45 focus group discussions were completed during Stage 1. Stage 2 incorporated eight participatory workshops that were an integral part of the research dissemination process to communities. The workshops also provided opportunity to review key themes and consolidate earlier findings as part of the research process. Qualitative data analysis used a grounded theory approach and was facilitated using qualitative data management software. Results A number of diverse considerations for the delivery of MC for HIV prevention in PNG were described, with conflicting views both between and within communities. Key issues included: location of the service, service provider, age eligibility, type of cut, community awareness and potential shame amongst youth. Key to developing appropriate health service delivery models was an appreciation of the differences in expectations and traditions of unique cultural groups in PNG. Establishing strong community coalitions, raising awareness and building trust were seen as integral to success. Conclusions Difficulties exist in the implementation of new programs in a pluralistic society such as PNG, particularly if tensions arise between biomedical knowledge and medico

  11. North Sea development activity surges

    SciTech Connect

    Not Available

    1992-08-10

    This paper reports that operators in the North Sea have reported a burst of upstream activity. Off the U.K.: Amoco (U.K.) Exploration Co. installed three jackets in its North Everest and Lomond fields. It also completed laying the Central Area Transmission System (CATS) pipeline, which will carry the fields' gas to shore. BP Exploration Operating Co. Ltd. installed the jacket for it Unity riser platform 5 {1/2} km from its Forties Charlie platform. Conoco (U.K.) Ltd. tested a successful appraisal well in Britannia field in Block 15/30, about 130 miles northeast of Aberdeen. In the Norwegian North Sea, Saga Petroleum AS placed Snorre oil and gas field on production 6 weeks ahead of schedule and 1.5 billion kroner under budget at a cost of 16.6 billion kroner; and downstream off the U.K., Phillips Petroleum Co. (U.K.) Ltd. awarded Allseas Marine Contractors SA, Essen, Belgium, a pipelay and trenching contract for its Ann field development project in Block 49/6a.

  12. Ratiometric Tension Probes for Mapping Receptor Forces and Clustering at Intermembrane Junctions.

    PubMed

    Ma, Victor Pui-Yan; Liu, Yang; Blanchfield, Lori; Su, Hanquan; Evavold, Brian D; Salaita, Khalid

    2016-07-13

    Short-range communication between cells is required for the survival of multicellular organisms. One mechanism of chemical signaling between adjacent cells employs surface displayed ligands and receptors that only bind when two cells make physical contact. Ligand-receptor complexes that form at the cell-cell junction and physically bridge two cells likely experience mechanical forces. A fundamental challenge in this area pertains to mapping the mechanical forces experienced by ligand-receptor complexes within such a fluid intermembrane junction. Herein, we describe the development of ratiometric tension probes for direct imaging of receptor tension, clustering, and lateral transport within a model cell-cell junction. These probes employ two fluorescent reporters that quantify both the ligand density and the ligand tension and thus generate a tension signal independent of clustering. As a proof-of-concept, we applied the ratiometric tension probes to map the forces experienced by the T-cell receptor (TCR) during activation and showed the first direct evidence that the TCR-ligand complex experiences sustained pN forces within a fluid membrane junction. We envision that the ratiometric tension probes will be broadly useful for investigating mechanotransduction in juxtacrine signaling pathways.

  13. (Re)Labeling Social Status: Promises and Tensions in Developing a College-Going Culture for Latina/o Youth in an Urban High School

    ERIC Educational Resources Information Center

    Achinstein, Betty; Curry, Marnie W.; Ogawa, Rodney T.

    2015-01-01

    Given educators' call to equalize educational opportunities, research is needed to illuminate promises and tensions in schools that resist negative labeling and sorting of nondominant youth. This article examines an urban high school that challenges traditional expectations for low-income, Latina/o students by engaging in "relabeling," a…

  14. Mental health and group tensions

    PubMed Central

    Koekebakker, J.

    1955-01-01

    The author points out that, with the development of technology in industry and the resultant more-technical roles demanded of workers, communication between them and between all persons in an industrial organization becomes of primary importance. This is particularly so because of the constant demands for change within an industrial organization. Any change, however minor, will inevitably involve a wide area of the organization, and special attention will therefore have to be paid to communication between persons. The author goes on to describe some of the investigations which have been made by the Institute of Preventive Medicine, Leyden, and indicates the extreme difficulty of obtaining accurate information. He shows also how the different attitudes of persons within a factory can lead to completely different perceptions of the field and of the attitudes of others within the same organization. He concludes that the main task of the mental health workers in industry lies in the prevention of tensions within it. One of the means of preventing tensions is to aim at a concept of “productive collaboration” within a factory. This task is seen as a special kind of therapy which must concern all levels of the factory. The author describes a procedure of investigation—diagnostic and therapeutic—within a factory, commencing with a phase of introduction, a pilot study, extensive individual interviewing, group interviewing, and a more specifically therapeutic phase, in which groups or specific individuals are enabled to talk their problems out. Finally, the investigating team must take steps to prevent situations of tension recurring, and, before leaving, must be certain that the plant is capable of maintaining a healthy equilibrium by itself. PMID:13276808

  15. Line tension between coexisting phases in monolayers and bilayers of amphiphilic molecules

    NASA Astrophysics Data System (ADS)

    Sriram, Indira; Schwartz, Daniel K.

    Phase coexistence is frequently observed in molecular monolayers and bilayers. The free energy per unit length of phase boundaries in these quasi-two-dimensional (2D) systems is known as line tension, and is directly analogous to surface tension in three dimensions. The existence of line tension implies the possibility of 2D capillary phenomena, a fundamentally intriguing possibility. Moreover, line tension has important implications with respect to the formation and stability of nm-scale features in thin films, ranging from lithographically-prepared molecular features in devices (e.g. sensor nanoarrays or molecular electronics) to signaling domains in biological membranes (i.e. lipid rafts). It has been proposed that such nm-scale domains may have important ramifications for budding and/or fusion in bilayer membranes. Various methods have been developed to measure line tension, including observations of domain boundary fluctuations, relaxation dynamics, nucleation rates, and others. The competition between line tension and long-range forces (e.g. electrostatic repulsion or curvature elasticity) can lead to a preferred equilibrium domain size, domain shape instabilities, or even unusual domain morphologies (e.g. stripe phases) near critical points. Since liquid crystalline mesophases are ubiquitous in 2D, it is not unusual for the line tension to be anisotropic; this can lead to non-circular domains exhibiting kinks and/or chirality. Recent efforts have been aimed at controlling line tension by the addition of line-active compounds that are analogous to surfactants potentially leading to the observation of new 2D "capillary" phenomena.

  16. Line tension between coexisting phases in monolayers and bilayers of amphiphilic molecules

    NASA Astrophysics Data System (ADS)

    Sriram, Indira; Schwartz, Daniel K.

    2012-06-01

    Phase coexistence is frequently observed in molecular monolayers and bilayers. The free energy per unit length of phase boundaries in these quasi-two-dimensional (2D) systems is known as line tension, and is directly analogous to surface tension in three dimensions. The existence of line tension implies the possibility of 2D capillary phenomena, a fundamentally intriguing possibility. Moreover, line tension has important implications with respect to the formation and stability of nm-scale features in thin films, ranging from lithographically-prepared molecular features in devices (e.g. sensor nanoarrays or molecular electronics) to signaling domains in biological membranes (i.e. lipid rafts). It has been proposed that such nm-scale domains may have important ramifications for budding and/or fusion in bilayer membranes. Various methods have been developed to measure line tension, including observations of domain boundary fluctuations, relaxation dynamics, nucleation rates, and others. The competition between line tension and long-range forces (e.g. electrostatic repulsion or curvature elasticity) can lead to a preferred equilibrium domain size, domain shape instabilities, or even unusual domain morphologies (e.g. stripe phases) near critical points. Since liquid crystalline mesophases are ubiquitous in 2D, it is not unusual for the line tension to be anisotropic; this can lead to non-circular domains exhibiting kinks and/or chirality. Recent efforts have been aimed at controlling line tension by the addition of line-active compounds that are analogous to surfactants potentially leading to the observation of new 2D “capillary” phenomena.

  17. Modification of Upper Thread Tensioner of Sewing Machine

    NASA Astrophysics Data System (ADS)

    Klouček, P.; Škop, P.

    Standard mechanical upper thread tensioner of sewing machines is more and more limited in use for industrial sewing machines due to increasing requests for quality and raising velocity of machines. If we omit mostly manual settings of force made only by sense, the most problematic things are influence of different friction coefficient of the different batch of threads and strong relation between thread tension and sewing machine velocity. The article describes the development focused to the elimination of the most significant disadvantages of a standard tensioner and mainly finding of new conception of the tensioner with electromagnetic brake, development and testing of its prototype.

  18. Cable tensioned membrane solar collector module with variable tension control

    DOEpatents

    Murphy, Lawrence M.

    1985-01-01

    Disclosed is a solar collector comprising a membrane for concentrating sunlight, a plurality of elongated structural members for suspending the membrane member thereon, and a plurality of control members for adjustably tensioning the membrane member, as well as for controlling a focus produced by the membrane members. Each control member is disposed at a different corresponding one of the plurality of structural members. The collector also comprises an elongated flexible tensioning member, which serves to stretch the membrane member and to thereafter hold it in tension, and a plurality of sleeve members, which serve to provide the membrane member with a desired surface contour during tensioning of the membrane member. The tensioning member is coupled to the structural members such that the tensioning member is adjustably tensioned through the structural members. The tensioning member is also coupled to the membrane member through the sleeve members such that the sleeve members uniformly and symmetrically stretch the membrane member upon applying tension to the tensioning member with the control members.

  19. Cable tensioned membrane solar collector module with variable tension control

    DOEpatents

    Murphy, L.M.

    1984-01-09

    Disclosed is a solar collector comprising a membrane member for concentrating sunlight, a plurality of elongated structural members for suspending the membrane member thereon, and a plurality of control members for adjustably tensioning the membrane member, as well as for controlling a focus produced by the membrane members. Each control member is disposed at a different corresponding one of the plurality of structural members. The collector also comprises an elongated flexible tensioning member, which serves to stretch the membrane member and to thereafter hold it in tension, and a plurality of sleeve members which serve to provide the membrane member with a desired surface contour during tensioning of the membrane member. The tensioning member is coupled to the structural members such that the tensioning member is adjustably tensioned through the structural members. The tensioning member is also coupled to the membrane member through the sleeve members such that the sleeve members uniformly and symmetrically stretch the membrane member upon applying tension to the tensioning member with the control members.

  20. Developing Internal Controls through Activities

    ERIC Educational Resources Information Center

    Barnes, F. Herbert

    2009-01-01

    Life events can include the Tuesday afternoon cooking class with the group worker or the Saturday afternoon football game, but in the sense that Fritz Redl thought of them, these activities are only threads in a fabric of living that includes all the elements of daily life: playing, working, school-based learning, learning through activities,…

  1. 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.

  2. Surface tension effects on submerged electrosprays

    PubMed Central

    Marín, Álvaro G.; Loscertales, Ignacio G.; Barrero, Antonio

    2012-01-01

    Electrosprays are a powerful technique to generate charged micro/nanodroplets. In the last century, the technique has been extensively studied, developed, and recognized with a shared Nobel price in Chemistry in 2002 for its wide spread application in mass spectrometry. However, nowadays techniques based on microfluidic devices are competing to be the next generation in atomization techniques. Therefore, an interesting development would be to integrate the electrospray technique into a microfluidic liquid-liquid device. Several works in the literature have attempted to build a microfluidic electrospray with disputable results. The main problem for its integration is the lack of knowledge of the working parameters of the liquid-liquid electrospray. The “submerged electrosprays” share similar properties as their counterparts in air. However, in the microfluidic generation of micro/nanodroplets, the liquid-liquid interfaces are normally stabilized with surface active agents, which might have critical effects on the electrospray behavior. In this work, we review the main properties of the submerged electrosprays in liquid baths with no surfactant, and we methodically study the behavior of the system for increasing surfactant concentrations. The different regimes found are then analyzed and compared with both classical and more recent experimental, theoretical and numerical studies. A very rich phenomenology is found when the surface tension is allowed to vary in the system. More concretely, the lower states of electrification achieved with the reduced surface tension regimes might be of interest in biological or biomedical applications in which excessive electrification can be hazardous for the encapsulated entities. PMID:24155865

  3. Growth factor involvement in tension-induced skeletal muscle growth

    NASA Technical Reports Server (NTRS)

    Vandenburgh, H. H.

    1987-01-01

    Muscle tissue culture techniques were developed to grow skeletal myofibers which differentiate into more adult-like myofibers. Mechanical simulation studies of these muscle cells in a newly developed mechanical cell simulator can now be performed to study growth processes in skeletal muscle. Conditions in the mechanical cell simulator were defined where mechanical activity can either prevent muscle wasting or stimulate muscle growth. The role of endogenous and exogenous growth factors in tension-induced muscle growth is being investigated under the defined conditions of tissue culture.

  4. Surface tension of ionic liquids and ionic liquid solutions.

    PubMed

    Tariq, Mohammad; Freire, Mara G; Saramago, Benilde; Coutinho, João A P; Lopes, José N Canongia; Rebelo, Luís Paulo N

    2012-01-21

    Some of the most active scientific research fronts of the past decade are centered on ionic liquids. These fluids present characteristic surface behavior and distinctive trends of their surface tension versus temperature. One way to explore and understand their unique nature is to study their surface properties. This critical review analyses most of the surface tension data reported between 2001 and 2010 (187 references).

  5. Coulomb string tension, asymptotic string tension, and the gluon chain

    DOE PAGES

    Greensite, Jeff; Szczepaniak, Adam P.

    2015-02-01

    We compute, via numerical simulations, the non-perturbative Coulomb potential and position-space ghost propagator in pure SU(3) gauge theory in Coulomb gauge. We find that that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

  6. From Vision to Reality: Managing Tensions in the Development and Implementation of an International Collaborative Partnership Programme for Institutional Change and Sustainable Development in Inclusive Education

    ERIC Educational Resources Information Center

    Siska, Jan; van Swet, Jacqueline; Pather, Sulochini; Rose, David

    2013-01-01

    The aim of this article is to consider the practical implications of international collaborative partnerships between and within higher education institutions (HEIs) in terms of the development of an international programme in Special Needs Education as well as its implementation. We first look at the heavy institutional demands set within…

  7. Human Development Program: Level V Activity Guide.

    ERIC Educational Resources Information Center

    Ball, Geraldine

    The curriculum guide presents the activities component of the Human Development Program for grade 5. The Human Development Program (HDP) is an affective curricular approach developed by psychologists to help teachers instill responsibility and self-confidence in children. The activity guide presents topics and directions for 180 sequential Human…

  8. BIOFEEDBACK TRAINING AND TENSION-TYPE HEADACHE.

    PubMed

    Šecić, Ana; Cvjeticanin, Timon; Kes, Vanja Bašić

    2016-03-01

    Biofeedback is a training method, which connects physiological and psychological processes in a person for the purposes of improving his/her physical, emotional, mental and spiritual health. In biofeedback treatment, an active role of the patient is stressed for him/her to be able to actively control the physiological and emotional processes. The aim of biofeedback is to improve the conscious control of the individual's involuntary physiological activity. Research has shown that biofeedback, either applied alone or in combination with other behavioral therapies (techniques), is an effective treatment for various medical and psychological disorders, from headache and hypertension to temporomandibular and attention deficit disorders. More than 90% of adults experience headache once a year, which makes headache one of the most common symptoms and diagnoses in medicine. Tension-type headaches occur in at least 40% of the population and their impact on the health insurance costs and diminished productivity is significant. Studies have shown that clinical biofeedback training is effective in treating headaches. Moreover, the authors stress the need for additional research and further development of methodology for this kind of research.

  9. Fragmentation in Biaxial Tension

    SciTech Connect

    Campbell, G H; Archbold, G C; Hurricane, O A; Miller, P L

    2006-06-13

    We have carried out an experiment that places a ductile stainless steel in a state of biaxial tension at a high rate of strain. The loading of the ductile metal spherical cap is performed by the detonation of a high explosive layer with a conforming geometry to expand the metal radially outwards. Simulations of the loading and expansion of the metal predict strain rates that compare well with experimental observations. A high percentage of the HE loaded material was recovered through a soft capture process and characterization of the recovered fragments provided high quality data, including uniform strain prior to failure and fragment size. These data were used with a modified fragmentation model to determine a fragmentation energy.

  10. Effects of tension on vortex-induced vibration (VIV) responses of a long tensioned cylinder in uniform flows

    NASA Astrophysics Data System (ADS)

    Kang, Ling; Ge, Fei; Wu, Xiaodong; Hong, Youshi

    2017-02-01

    The effects of tension on vortex-induced vibration (VIV) responses for a tension-dominated long cylinder with an aspect ratio of 550 in uniform flows are experimentally investigated in this paper. The results show that elevated tension suppresses fluctuations of maximum displacement with respect to flow velocity and makes chaotic VIV more likely to appear. With respect to periodic VIV, if elevated tension is applied, the dominant vibration frequency in the in-line (IL) direction will switch from a fundamental vibration frequency to twice the value of the fundamental vibration frequency, which results in a ratio of the dominant vibration frequency in the IL direction to that in the cross-flow direction of 2.0. The suppression of the elevated tension in the fluctuation of the maximum displacement causes the axial tension to become an active control parameter for the VIV maximum displacement of a tension-dominated long riser or tether of an engineering structure in deep oceans. However, the axial tension must be optimized before being used since the high dominant vibration frequency due to the elevated tension may unfavorably affect the fatigue life of the riser or tether.

  11. Navy GTE seal development activity

    NASA Technical Reports Server (NTRS)

    Grala, Carl P.

    1993-01-01

    Under the auspices of the Integrated High Performance Turbine Engine Technology Initiative, the Naval Air Warfare Center conducts advanced development programs for demonstration in the next generation of air-breathing propulsion systems. Among the target technologies are gas path and lube oil seals. Two development efforts currently being managed by NAWCAD are the High Performance Compressor Discharge Film-Riding Face Seal and the Subsonic Core High Speed Air/Oil Seal. The High Performance Compressor Discharge Film-Riding Face Seal Program aims at reducing parasitic leakage through application of a film-riding face sea concept to the compressor discharge location of a Phase 2 IHPTET engine. An order-of-magnitude leakage reduction relative to current labyrinth seal configurations is expected. Performance goals for these seals are (1) 1200 F air temperature, (2) 800 feet-per-second surface velocity, and (3) 600 SPI differential pressure. The two designs chosen for fabrication and rig test are a spiral groove and a Rayleigh step seal. Rig testing is currently underway. The Subsonic Core High Speed Air/Oil Seal Program is developing shaft-to-ground seals for next-generation propulsion systems that will minimize leakage and provide full life. Significantly higher rotor speeds and temperatures will be experienced. Technologies being exploited include, hydrodynamic lift assist features, ultra light weight designs, and improved cooling schemes. Parametric testing has been completed; a final seal design is entering the endurance test phase.

  12. Navy GTE seal development activity

    NASA Astrophysics Data System (ADS)

    Grala, Carl P.

    1993-10-01

    Under the auspices of the Integrated High Performance Turbine Engine Technology Initiative, the Naval Air Warfare Center conducts advanced development programs for demonstration in the next generation of air-breathing propulsion systems. Among the target technologies are gas path and lube oil seals. Two development efforts currently being managed by NAWCAD are the High Performance Compressor Discharge Film-Riding Face Seal and the Subsonic Core High Speed Air/Oil Seal. The High Performance Compressor Discharge Film-Riding Face Seal Program aims at reducing parasitic leakage through application of a film-riding face sea concept to the compressor discharge location of a Phase 2 IHPTET engine. An order-of-magnitude leakage reduction relative to current labyrinth seal configurations is expected. Performance goals for these seals are (1) 1200 F air temperature, (2) 800 feet-per-second surface velocity, and (3) 600 SPI differential pressure. The two designs chosen for fabrication and rig test are a spiral groove and a Rayleigh step seal. Rig testing is currently underway. The Subsonic Core High Speed Air/Oil Seal Program is developing shaft-to-ground seals for next-generation propulsion systems that will minimize leakage and provide full life. Significantly higher rotor speeds and temperatures will be experienced. Technologies being exploited include, hydrodynamic lift assist features, ultra light weight designs, and improved cooling schemes. Parametric testing has been completed; a final seal design is entering the endurance test phase.

  13. Spontaneous network activity and synaptic development

    PubMed Central

    Kerschensteiner, Daniel

    2014-01-01

    Throughout development, the nervous system produces patterned spontaneous activity. Research over the last two decades has revealed a core group of mechanisms that mediate spontaneous activity in diverse circuits. Many circuits engage several of these mechanisms sequentially to accommodate developmental changes in connectivity. In addition to shared mechanisms, activity propagates through developing circuits and neuronal pathways (i.e. linked circuits in different brain areas) in stereotypic patterns. Increasing evidence suggests that spontaneous network activity shapes synaptic development in vivo. Variations in activity-dependent plasticity may explain how similar mechanisms and patterns of activity can be employed to establish diverse circuits. Here, I will review common mechanisms and patterns of spontaneous activity in emerging neural networks and discuss recent insights into their contribution to synaptic development. PMID:24280071

  14. Confronting Racial and Religious Tensions

    ERIC Educational Resources Information Center

    Wessler, Stephen

    2011-01-01

    When a community's demographics change quickly in terms of racial, religious, or ethnic makeup, Wessler notes, tension surfaces. Schools are the likeliest place for these kinds of tensions to openly come to a head. Schools can't always avoid conflicts among students who feel mutual prejudice and suspicion. But schools can address simmering…

  15. A Tension-Based Model Distinguishes Hypertrophic versus Dilated Cardiomyopathy.

    PubMed

    Davis, Jennifer; Davis, L Craig; Correll, Robert N; Makarewich, Catherine A; Schwanekamp, Jennifer A; Moussavi-Harami, Farid; Wang, Dan; York, Allen J; Wu, Haodi; Houser, Steven R; Seidman, Christine E; Seidman, Jonathan G; Regnier, Michael; Metzger, Joseph M; Wu, Joseph C; Molkentin, Jeffery D

    2016-05-19

    The heart either hypertrophies or dilates in response to familial mutations in genes encoding sarcomeric proteins, which are responsible for contraction and pumping. These mutations typically alter calcium-dependent tension generation within the sarcomeres, but how this translates into the spectrum of hypertrophic versus dilated cardiomyopathy is unknown. By generating a series of cardiac-specific mouse models that permit the systematic tuning of sarcomeric tension generation and calcium fluxing, we identify a significant relationship between the magnitude of tension developed over time and heart growth. When formulated into a computational model, the integral of myofilament tension development predicts hypertrophic and dilated cardiomyopathies in mice associated with essentially any sarcomeric gene mutations, but also accurately predicts human cardiac phenotypes from data generated in induced-pluripotent-stem-cell-derived myocytes from familial cardiomyopathy patients. This tension-based model also has the potential to inform pharmacologic treatment options in cardiomyopathy patients.

  16. Observations on intrauterine oxygen tension measured by fibre-optic microsensors.

    PubMed

    Ottosen, Lars D M; Hindkaer, Johnny; Husth, Merete; Petersen, Dorrit Elschner; Kirk, John; Ingerslev, Hans Jakob

    2006-09-01

    Understanding the biology of reproductive organs is essential for the development of assisted reproductive techniques. There is at present no direct evidence for either the concentration and dynamics of intrauterine oxygen tension at the endometrial surface, nor its importance for the receptiveness of the endometrium. In this study a new method measured mid-cycle (ranging from day 12-18) endometrial surface oxygen tension in 21 patients referred to intrauterine insemination (IUI). Time series was measured online for a period of 5-10 min. The (mean) individual oxygen tension among patients varied from 4 to 27% air saturation. Overall mean oxygen tension among all patients was 11.8% air saturation. Within the same patient, considerable time-related variations were observed. Some patients exhibited rhythmic oscillations with a frequency in the order of 1 min, whereas others did not show any regular patterns. A good description of endometrial surface oxygen concentration and dynamics was thus obtained, but given the relatively small number of participants, an association with pregnancy following insemination could not be established. Further studies using this new method could elucidate the association between individual intrauterine activity, embryo implantation and endometrial surface oxygen tension.

  17. Surface tension and long range corrections of cylindrical interfaces.

    PubMed

    Bourasseau, E; Malfreyt, P; Ghoufi, A

    2015-12-21

    The calculation of the surface tension of curved interfaces has been deeply investigated from molecular simulation during this last past decade. Recently, the thermodynamic Test-Area (TA) approach has been extended to the calculation of surface tension of curved interfaces. In the case of the cylindrical vapour-liquid interfaces of water and Lennard-Jones fluids, it was shown that the surface tension was independent of the curvature of the interface. In addition, the surface tension of the cylindrical interface is higher than that of the planar interface. Molecular simulations of cylindrical interfaces have been so far performed (i) by using a shifted potential, (ii) by means of large cutoff without periodic boundary conditions, or (iii) by ignoring the long range corrections to the surface tension due to the difficulty to estimate them. Indeed, unlike the planar interfaces there are no available operational expressions to consider the tail corrections to the surface tension of cylindrical interfaces. We propose here to develop the long range corrections of the surface tension for cylindrical interfaces by using the non-exponential TA (TA2) method. We also extend the formulation of the Mecke-Winkelmann corrections initially developed for planar surfaces to cylindrical interfaces. We complete this study by the calculation of the surface tension of cylindrical surfaces of liquid tin and copper using the embedded atom model potentials.

  18. Surface tension and long range corrections of cylindrical interfaces

    SciTech Connect

    Bourasseau, E.; Ghoufi, A.

    2015-12-21

    The calculation of the surface tension of curved interfaces has been deeply investigated from molecular simulation during this last past decade. Recently, the thermodynamic Test-Area (TA) approach has been extended to the calculation of surface tension of curved interfaces. In the case of the cylindrical vapour-liquid interfaces of water and Lennard-Jones fluids, it was shown that the surface tension was independent of the curvature of the interface. In addition, the surface tension of the cylindrical interface is higher than that of the planar interface. Molecular simulations of cylindrical interfaces have been so far performed (i) by using a shifted potential, (ii) by means of large cutoff without periodic boundary conditions, or (iii) by ignoring the long range corrections to the surface tension due to the difficulty to estimate them. Indeed, unlike the planar interfaces there are no available operational expressions to consider the tail corrections to the surface tension of cylindrical interfaces. We propose here to develop the long range corrections of the surface tension for cylindrical interfaces by using the non-exponential TA (TA2) method. We also extend the formulation of the Mecke-Winkelmann corrections initially developed for planar surfaces to cylindrical interfaces. We complete this study by the calculation of the surface tension of cylindrical surfaces of liquid tin and copper using the embedded atom model potentials.

  19. 33 CFR 147.811 - Ram-Powell Tension Leg Platform safety zone.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Ram-Powell Tension Leg Platform... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.811 Ram-Powell Tension Leg Platform safety zone. (a) Description. The Ram-Powell Tension Leg Platform (Ram-Powell TLP) is located...

  20. 33 CFR 147.811 - Ram-Powell Tension Leg Platform safety zone.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Ram-Powell Tension Leg Platform... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.811 Ram-Powell Tension Leg Platform safety zone. (a) Description. The Ram-Powell Tension Leg Platform (Ram-Powell TLP) is located...

  1. 33 CFR 147.811 - Ram-Powell Tension Leg Platform safety zone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Ram-Powell Tension Leg Platform... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.811 Ram-Powell Tension Leg Platform safety zone. (a) Description. The Ram-Powell Tension Leg Platform (Ram-Powell TLP) is located...

  2. 33 CFR 147.811 - Ram-Powell Tension Leg Platform safety zone.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Ram-Powell Tension Leg Platform... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.811 Ram-Powell Tension Leg Platform safety zone. (a) Description. The Ram-Powell Tension Leg Platform (Ram-Powell TLP) is located...

  3. 33 CFR 147.811 - Ram-Powell Tension Leg Platform safety zone.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Ram-Powell Tension Leg Platform... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.811 Ram-Powell Tension Leg Platform safety zone. (a) Description. The Ram-Powell Tension Leg Platform (Ram-Powell TLP) is located...

  4. 33 CFR 147.809 - Mars Tension Leg Platform safety zone.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Mars Tension Leg Platform safety... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.809 Mars Tension Leg Platform safety zone. (a) Description. The Mars Tension Leg Platform (Mars TLP) is located at position...

  5. 33 CFR 147.809 - Mars Tension Leg Platform safety zone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Mars Tension Leg Platform safety... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.809 Mars Tension Leg Platform safety zone. (a) Description. The Mars Tension Leg Platform (Mars TLP) is located at position...

  6. 33 CFR 147.809 - Mars Tension Leg Platform safety zone.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Mars Tension Leg Platform safety... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.809 Mars Tension Leg Platform safety zone. (a) Description. The Mars Tension Leg Platform (Mars TLP) is located at position...

  7. 33 CFR 147.809 - Mars Tension Leg Platform safety zone.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Mars Tension Leg Platform safety... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.809 Mars Tension Leg Platform safety zone. (a) Description. The Mars Tension Leg Platform (Mars TLP) is located at position...

  8. 33 CFR 147.809 - Mars Tension Leg Platform safety zone.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Mars Tension Leg Platform safety... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.809 Mars Tension Leg Platform safety zone. (a) Description. The Mars Tension Leg Platform (Mars TLP) is located at position...

  9. 33 CFR 147.837 - Marco Polo Tension Leg Platform safety zone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Marco Polo Tension Leg Platform... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.837 Marco Polo Tension Leg Platform safety zone. (a) Description. Marco Polo Tension Leg Platform, Green Canyon 608 (GC 608),...

  10. The sarcomere length-tension relation in skeletal muscle

    PubMed Central

    1978-01-01

    Tension development during isometric tetani in single fibers of frog semitendinosus muscle occurs in three phases: (a) in initial fast-rise phase; (b) a slow-rise phase; and (c) a plateau, which lasts greater than 10 s. The slow-rise phase has previously been assumed to rise out of a progressive increase of sarcomere length dispersion along the fiber (Gordon et al. 1966. J. Physiol. [Lond.]. 184:143--169;184:170-- 192). Consequently, the "true" tetanic tension has been considered to be the one existing before the onset of the slow-rise phase; this is obtained by extrapolating the slowly rising tension back to the start of the tetanus. In the study by Gordon et al. (1966. J. Physiol. [Lond.] 184:170--192), as well as in the present study, the relation between this extrapolated tension and sarcomere length gave the familiar linear descending limb of the length-tension relation. We tested the assumption that the slow rise of tension was due to a progressive increase in sarcomere length dispersion. During the fast rise, the slow rise, and the plateau of tension, the sarcomere length dispersion at any area along the muscle was less than 4% of the average sarcomere length. Therefore, a progressive increase of sarcomere length dispersion during contraction appears unable to account for the slow rise of tetanic tension. A sarcomere length-tension relation was constructed from the levels of tension and sarcomere length measured during the plateau. Tension was independent of sarcomere length between 1.9 and 2.6 microgram, and declined to 50% maximal at 3.4 microgram. This result is difficult to reconcile with the cross-bridge model of force generation. PMID:309929

  11. Exploring the inhibitory effect of membrane tension on cell polarization

    PubMed Central

    Wang, Jing; Yang, Gen; Ouyang, Qi; Wang, Yugang; Zhang, Lei

    2017-01-01

    Cell polarization toward an attractant is influenced by both physical and chemical factors. Most existing mathematical models are based on reaction-diffusion systems and only focus on the chemical process occurring during cell polarization. However, membrane tension has been shown to act as a long-range inhibitor of cell polarization. Here, we present a cell polarization model incorporating the interplay between Rac GTPase, filamentous actin (F-actin), and cell membrane tension. We further test the predictions of this model by performing single cell measurements of the spontaneous polarization of cancer stem cells (CSCs) and non-stem cancer cells (NSCCs), as the former have lower cell membrane tension. Based on both our model and the experimental results, cell polarization is more sensitive to stimuli under low membrane tension, and high membrane tension improves the robustness and stability of cell polarization such that polarization persists under random perturbations. Furthermore, our simulations are the first to recapitulate the experimental results described by Houk et al., revealing that aspiration (elevation of tension) and release (reduction of tension) result in a decrease in and recovery of the activity of Rac-GTP, respectively, and that the relaxation of tension induces new polarity of the cell body when a cell with the pseudopod-neck-body morphology is severed. PMID:28135277

  12. Fatigue Damage in Notched Composite Laminates Under Tension-Tension Cyclic Loads

    NASA Technical Reports Server (NTRS)

    Stinchcomb, W. W.; Henneke, E. G.; Reifsnider, K. L.; Kress, G. R.

    1985-01-01

    The results are given of an investigation to determine the damage states which develop in graphite epoxy laminates with center holes due to tension-tension cyclic loads, to determine the influence of stacking sequence on the initiation and interaction of damage modes and the process of damage development, and to establish the relationships between the damage states and the strength, stiffness, and life of the laminates. Two quasi-isotropic laminates were selected to give different distributions of interlaminar stresses around the hole. The laminates were tested under cyclic loads (R=0.1, 10 Hz) at maximum stresses ranging between 60 and 95 percent of the notched tensile strength.

  13. Advanced Technology Development for Active Acoustic Liners

    NASA Technical Reports Server (NTRS)

    Sheplak, Mark; Cattafesta, Louis N., III; Nishida, Toshikazu; Kurdila, Andrew J.

    2001-01-01

    Objectives include: (1) Develop electro-mechanical/acoustic models of a Helmholtz resonator possessing a compliant diaphragm coupled to a piezoelectric device; (2) Design and fabricate the energy reclamation module and active Helmholtz resonator; (3) Develop and build appropriate energy reclamation/storage circuit; (4) Develop and fabricate appropriate piezoelectric shunt circuit to tune the compliance of the active Helmholtz resonator via a variable capacitor; (5) Quantify energy reclamation module efficiency in a grazing-flow plane wave tube possessing known acoustic energy input; and (6) Quantify actively tuned Helmholtz resonator performance in grazing-flow plane wave tube for a white-noise input

  14. Growth factor involvement in tension-induced skeletal muscle growth

    NASA Technical Reports Server (NTRS)

    Vandenburgh, Herman H.

    1993-01-01

    Long-term manned space travel will require a better understanding of skeletal muscle atrophy which results from microgravity. Astronaut strength and dexterity must be maintained for normal mission operations and for emergency situations. Although exercise in space slows the rate of muscle loss, it does not prevent it. A biochemical understanding of how gravity/tension/exercise help to maintain muscle size by altering protein synthesis and/or degradation rate should ultimately allow pharmacological intervention to prevent muscle atrophy in microgravity. The overall objective is to examine some of the basic biochemical processes involved in tension-induced muscle growth. With an experimental in vitro system, the role of exogenous and endogenous muscle growth factors in mechanically stimulated muscle growth are examined. Differentiated avian skeletal myofibers can be 'exercised' in tissue culture using a newly developed dynamic mechanical cell stimulator device which simulates different muscle activity patterns. Patterns of mechanical activity which significantly affect muscle growth and metabolic characteristics were found. Both exogenous and endogenous growth factors are essential for tension-induced muscle growth. Exogenous growth factors found in serum, such as insulin, insulin-like growth factors, and steroids, are important regulators of muscle protein turnover rates and mechanically-induced muscle growth. Endogenous growth factors are synthesized and released into the culture medium when muscle cells are mechanically stimulated. At least one family of mechanically induced endogenous factors, the prostaglandins, help to regulate the rates of protein turnover in muscle cells. Endogenously synthesized IGF-1 is another. The interaction of muscle mechanical activity and these growth factors in the regulation of muscle protein turnover rates with our in vitro model system is studied.

  15. Longitudinal Multilevel Modeling of Facial Pain, Muscle Tension, and Stress.

    PubMed

    Glaros, A G; Marszalek, J M; Williams, K B

    2016-04-01

    The role of masticatory muscle activation on pain in temporomandibular muscle and joint disorders (TMJD) is controversial. This single-group, prospective panel study examined the relationships among masticatory muscle tension, emotional distress, and TMJD pain in a sample of 7,023 observations obtained from 171 individuals using longitudinal multilevel modeling. Three main hypotheses were tested. The first posited that emotional distress and muscle tension directly influenced pain (hypothesis 1a: Distress → TMJD Pain; hypothesis 1b: Muscle Tension → TMJD Pain). The second posited that emotional distress directly influenced muscle tension (Distress → Muscle Tension), and the third posited that the effect of emotional distress on pain was mediated by muscle tension (Distress → Muscle Tension → TMJD pain). We also examined the fit of the data to possible alternative models. All the data used in this study were collected via an experience sampling methodology. The fit of the preferred models was better than that of the alternative models, with the preferred models explaining large proportions of the data, especially for level 2 variance (hypothesis 1a = 41% variance; hypothesis 1b = 69% variance; hypothesis 2 = 48% variance). In the mediation model, the addition of muscle tension to the model reduced the impact of emotional distress. The findings support a causal role for masticatory muscle tension in TMJD pain. Clinically, the results suggest that addressing tension and other oral parafunctions in those diagnosed with TMJDs should be an important part of the conservative, noninvasive care of individuals diagnosed with the myofascial pain or arthralgia of TMJD.

  16. Characterization of optimal resting tension in human pulmonary arteries

    PubMed Central

    Hussain, Azar; Bennett, Robert T; Chaudhry, Mubarak A; Qadri, Syed S; Cowen, Mike; Morice, Alyn H; Loubani, Mahmoud

    2016-01-01

    AIM To determine the optimum resting tension (ORT) for in vitro human pulmonary artery (PA) ring preparations. METHODS Pulmonary arteries were dissected from disease free sections of the resected lung in the operating theatre and tissue samples were directly sent to the laboratory in Krebs-Henseleit solution (Krebs). The pulmonary arteries were then cut into 2 mm long rings. PA rings were mounted in 25 mL organ baths or 8 mL myograph chambers containing Krebs compound (37 °C, bubbled with 21% O2: 5% CO2) to measure changes in isometric tension. The resting tension was set at 1-gram force (gf) with vessels being left static to equilibrate for duration of one hour. Baseline contractile reactions to 40 mmol/L KCl were obtained from a resting tension of 1 gf. Contractile reactions to 40 mmol/L KCl were then obtained from stepwise increases in resting tension (1.2, 1.4, 1.6, 1.8 and 2.0 gf). RESULTS Twenty PA rings of internal diameter between 2-4 mm were prepared from 4 patients. In human PA rings incrementing the tension during rest stance by 0.6 gf, up to 1.6 gf significantly augmented the 40 mmol/L KCl stimulated tension. Further enhancement of active tension by 0.4 gf, up to 2.0 gf mitigate the 40 mmol/L KCl stimulated reaction. Both Myograph and the organ bath demonstrated identical conclusions, supporting that the radial optimal resting tension for human PA ring was 1.61 g. CONCLUSION The radial optimal resting tension in our experiment is 1.61 gf (15.78 mN) for human PA rings. PMID:27721938

  17. Dynamical Modeling of Surface Tension

    NASA Technical Reports Server (NTRS)

    Brackbill, Jeremiah U.; Kothe, Douglas B.

    1996-01-01

    In a recent review it is said that free-surface flows 'represent some of the difficult remaining challenges in computational fluid dynamics'. There has been progress with the development of new approaches to treating interfaces, such as the level-set method and the improvement of older methods such as the VOF method. A common theme of many of the new developments has been the regularization of discontinuities at the interface. One example of this approach is the continuum surface force (CSF) formulation for surface tension, which replaces the surface stress given by Laplace's equation by an equivalent volume force. Here, we describe how CSF formulation might be made more useful. Specifically, we consider a derivation of the CSF equations from a minimization of surface energy as outlined by Jacqmin (1996). This reformulation suggests that if one eliminates the computation of curvature in terms of a unit normal vector, parasitic currents may be eliminated. For this reformulation to work, it is necessary that transition region thickness be controlled. Various means for this, in addition to the one discussed by Jacqmin (1996), are discussed.

  18. The Golden Spiral Flap: A New Flap Design that Allows for Closure of Larger Wounds under Reduced Tension – How Studying Nature’s Own Design Led to the Development of a New Surgical Technique

    PubMed Central

    Paul, Sharad P.

    2016-01-01

    This paper details the study of biodynamic excisional skin tension lines on the scalp and the development of a new flap technique for closure of scalp wounds. Recently, a study by this author, on pigskin, replicated whorls by placing tissue under rapid stretch using saline tissue expanders, by recreating rapid dermo-epidermal shear of skin – thereby concluding that the golden spiral pattern is nature’s own pattern for rapid expansion. Given the relationship between tissue expansion and stretch has been shown to cause deformation gradients that have both elastic and growth factors, the author set out to test the hypothesis that a golden spiral pattern therefore would be more efficient at closing wounds under less tension when compared with standard semicircular rotational flap patterns. The author conducted a series of experiments, both on pigskin (to first confirm the hypothesis, using a recently developed computerized tensiometer) and later a clinical study. This paper presents a new random pivotal flap technique for skin closures on the head and neck: the golden spiral flap. Biomechanics, planning, and advantages of this new flap are described in this paper. PMID:27900320

  19. The Golden Spiral Flap: A New Flap Design that Allows for Closure of Larger Wounds under Reduced Tension - How Studying Nature's Own Design Led to the Development of a New Surgical Technique.

    PubMed

    Paul, Sharad P

    2016-01-01

    This paper details the study of biodynamic excisional skin tension lines on the scalp and the development of a new flap technique for closure of scalp wounds. Recently, a study by this author, on pigskin, replicated whorls by placing tissue under rapid stretch using saline tissue expanders, by recreating rapid dermo-epidermal shear of skin - thereby concluding that the golden spiral pattern is nature's own pattern for rapid expansion. Given the relationship between tissue expansion and stretch has been shown to cause deformation gradients that have both elastic and growth factors, the author set out to test the hypothesis that a golden spiral pattern therefore would be more efficient at closing wounds under less tension when compared with standard semicircular rotational flap patterns. The author conducted a series of experiments, both on pigskin (to first confirm the hypothesis, using a recently developed computerized tensiometer) and later a clinical study. This paper presents a new random pivotal flap technique for skin closures on the head and neck: the golden spiral flap. Biomechanics, planning, and advantages of this new flap are described in this paper.

  20. Tension-compression-tension tertiary twins in coarse-grained polycrystalline pure magnesium at room temperature

    DOE PAGES

    Yu, Qin; Jiang, Yanyao; Wang, Jian

    2015-04-07

    Using electron backscatter diffraction, the microstructural features of tension–compression–tension (T–C–T) tertiary twins are studied in coarse-grained pure polycrystalline magnesium subjected to monotonic compression along the extrusion direction in ambient air. T–C–T tertiary twins are developed due to the formation of a compression–tension double twin inside a primary tension twin. All the observed T–C–T twin variants are of TiCjTj type. TiCi+1Ti+1 (or TiCi–1Ti–1) variants are observed more frequently than TiCi+2Ti+2 (or TiCi–2Ti–2) variants. Moreover, the number of tertiary twin lamellae increases with the applied compressive strain.

  1. Laboratory Activities for Developing Process Skills.

    ERIC Educational Resources Information Center

    Institute for Services to Education, Inc., Washington, DC.

    This workbook contains laboratory exercises designed for use in a college introductory biology course. Each exercise helps the student develop a basic science skill. The exercises are arranged in a hierarchical sequence suggesting the scientific method. Each skill facilitates the development of succeeding ones. Activities include Use of the…

  2. Separation anxiety: Stress, tension and cytokinesis

    SciTech Connect

    Mohan, Krithika; Iglesias, Pablo A.; Robinson, Douglas N.

    2012-07-15

    Cytokinesis, the physical separation of a mother cell into two daughter cells, progresses through a series of well-defined changes in morphology. These changes involve distinct biochemical and mechanical processes. Here, we review the mechanical features of cells during cytokinesis, discussing both the material properties as well as sources of stresses, both active and passive, which lead to the observed changes in morphology. We also describe a mechanosensory feedback control system that regulates protein localization and shape progression during cytokinesis. -- Highlights: Black-Right-Pointing-Pointer Cytokinesis progresses through three distinct mechanical phases. Black-Right-Pointing-Pointer Cortical tension initially resists deformation of mother cell. Black-Right-Pointing-Pointer Late in cytokinesis, cortical tension provides stress, enabling furrow ingression. Black-Right-Pointing-Pointer A mechanosensory feedback control system regulates cytokinesis.

  3. Muscle trigger point therapy in tension-type headache.

    PubMed

    Alonso-Blanco, Cristina; de-la-Llave-Rincón, Ana Isabel; Fernández-de-las-Peñas, César

    2012-03-01

    Recent evidence suggests that active trigger points (TrPs) in neck and shoulder muscles contribute to tension-type headache. Active TrPs within the suboccipital, upper trapezius, sternocleidomastoid, temporalis, superior oblique and lateral rectus muscles have been associated with chronic and episodic tension-type headache forms. It seems that the pain profile of this headache may be provoked by referred pain from active TrPs in the posterior cervical, head and shoulder muscles. In fact, the presence of active TrPs has been related to a higher degree of sensitization in tension-type headache. Different therapeutic approaches are proposed for proper TrP management. Preliminary evidence indicates that inactivation of TrPs may be effective for the management of tension-type headache, particularly in a subgroup of patients who may respond positively to this approach. Different treatment approaches targeted to TrP inactivation are discussed in the current paper, focusing on tension-type headache. New studies are needed to further delineate the relationship between muscle TrP inactivation and tension-type headache.

  4. Studies on monolayers. Part 1. Surface tension and absorption spectroscopic measurements of monolayers of surface-active azo and stilbene dyes

    SciTech Connect

    Heesemann, J.

    1980-03-26

    In order to develop new molecules as function components of monolayer assemblies, a series of 9 surface-active azo and stilbene compounds are synthesized. Their monolayer properties at the air-water interface are studied by surface pressure-surface area measurements and spectroscopic techniques. The results show that small changes in the molecular structure of the surfactants (such as, length of the fatty acid chain and type of the chromphore) have an immense influence on the monolayer properties. For monolayers of compounds I and III-VIII, van der Walls-like isotherms are obtained, which show a liquid expanded state, a phase transition region, and a condensed state. From monolayer absorbance spectra it is found that in the liquid expanded state at 100 to 110 sq angstroms/molecule the chromphores lie flatly on the water surface, forming monomers. The phase transition region of the isotherms can be assigned to a change of orientation of the chromophore axis (horizontal to vertical) and an aggregation process of the chromophores (monomers to H aggregates). 20 references.

  5. Spontaneous activity in the developing auditory system.

    PubMed

    Wang, Han Chin; Bergles, Dwight E

    2015-07-01

    Spontaneous electrical activity is a common feature of sensory systems during early development. This sensory-independent neuronal activity has been implicated in promoting their survival and maturation, as well as growth and refinement of their projections to yield circuits that can rapidly extract information about the external world. Periodic bursts of action potentials occur in auditory neurons of mammals before hearing onset. This activity is induced by inner hair cells (IHCs) within the developing cochlea, which establish functional connections with spiral ganglion neurons (SGNs) several weeks before they are capable of detecting external sounds. During this pre-hearing period, IHCs fire periodic bursts of Ca(2+) action potentials that excite SGNs, triggering brief but intense periods of activity that pass through auditory centers of the brain. Although spontaneous activity requires input from IHCs, there is ongoing debate about whether IHCs are intrinsically active and their firing periodically interrupted by external inhibitory input (IHC-inhibition model), or are intrinsically silent and their firing periodically promoted by an external excitatory stimulus (IHC-excitation model). There is accumulating evidence that inner supporting cells in Kölliker's organ spontaneously release ATP during this time, which can induce bursts of Ca(2+) spikes in IHCs that recapitulate many features of auditory neuron activity observed in vivo. Nevertheless, the role of supporting cells in this process remains to be established in vivo. A greater understanding of the molecular mechanisms responsible for generating IHC activity in the developing cochlea will help reveal how these events contribute to the maturation of nascent auditory circuits.

  6. Child Development: An Active Learning Approach

    ERIC Educational Resources Information Center

    Levine, Laura E.; Munsch, Joyce

    2010-01-01

    Within each chapter of this innovative topical text, the authors engage students by demonstrating the wide range of real-world applications of psychological research connected to child development. In particular, the distinctive Active Learning features incorporated throughout the book foster a dynamic and personal learning process for students.…

  7. Developing Web Literacy in Collaborative Inquiry Activities

    ERIC Educational Resources Information Center

    Kuiper, Els; Volman, Monique; Terwel, Jan

    2009-01-01

    Although many children are technically skilled in using the Web, their competences to use it in a critical and meaningful way are usually less well developed. In this article, we report on a multiple case study focusing on the possibilities and limitations of collaborative inquiry activities as an appropriate context to acquire Web literacy skills…

  8. Moving toward Teamwork through Professional Development Activities

    ERIC Educational Resources Information Center

    Fitzgerald, Meghan M.; Theilheimer, Rachel

    2013-01-01

    This qualitative study of three Head Start Centers analyzed surveys, interviews, and focus group data to determine how education coordinators, teachers, and teacher assistants believed professional development activities could support teamwork at their centers. The researchers sorted data related to teamwork into four categories: knowledge and…

  9. Development of a space activity suit

    NASA Technical Reports Server (NTRS)

    Annis, J. F.; Webb, P.

    1971-01-01

    The development of a series of prototype space activity suit (SAS) assemblies is discussed. The SAS is a new type of pressure suit designed especially for extravehicular activity. It consists of a set of carefully tailored elastic fabric garments which have been engineered to supply sufficient counterpressure to the body to permit subjects to breath O2 at pressures up to 200 mm Hg without circulatory difficulty. A closed, positive pressure breathing system (PPBS) and a full bubble helmet were also developed to complete the system. The ultimate goal of the SAS is to improve the range of activity and decrease the energy cost of work associated with wearing conventional gas filled pressure suits. Results are presented from both laboratory (1 atmosphere) and altitude chamber tests with subjects wearing various SAS assemblies. In laboratory tests lasting up to three hours, the SAS was worn while subjects breathed O2 at pressures up to 170 mm Hg without developing physiological problems. The only physiological symptoms apparent were a moderate tachycardia related to breathing pressures above 130 mm Hg, and a small collection of edema fluid in the hands. Both problems were considered to be related to areas of under-pressurization by the garments. These problems, it is suggested, can ultimately be corrected by the development of new elastic fabrics and tailoring techniques. Energy cost of activity, and mobility and dexterity of subjects in the SAS, were found to be superior to those in comparable tests on subjects in full pressure suits.

  10. Developing a New Activity: STUDENT APPROVED

    ERIC Educational Resources Information Center

    Smit, Julie; Cavallo-Medved, Dora; Poling, Kirsten

    2011-01-01

    Do you have an idea for a new activity or laboratory exercise that you would like to incorporate into your course but feel unsure as to how it will be received by your students? This was our concern when developing first-year biology labs for a biology majors' course at University of Windsor. Through a Centred on Learning Innovation Fund (CLIF)…

  11. Active Learning through Toy Design and Development

    ERIC Educational Resources Information Center

    Sirinterlikci, Arif; Zane, Linda; Sirinterlikci, Aleea L.

    2009-01-01

    This article presents an initiative that is based on active learning pedagogy by engaging elementary and middle school students in the toy design and development field. The case study presented in this article is about student learning experiences during their participation in the TOYchallenge National Toy Design Competition. Students followed the…

  12. Macromolecular crowding meets oxygen tension in human mesenchymal stem cell culture - A step closer to physiologically relevant in vitro organogenesis

    PubMed Central

    Cigognini, Daniela; Gaspar, Diana; Kumar, Pramod; Satyam, Abhigyan; Alagesan, Senthilkumar; Sanz-Nogués, Clara; Griffin, Matthew; O’Brien, Timothy; Pandit, Abhay; Zeugolis, Dimitrios I.

    2016-01-01

    Modular tissue engineering is based on the cells’ innate ability to create bottom-up supramolecular assemblies with efficiency and efficacy still unmatched by man-made devices. Although the regenerative potential of such tissue substitutes has been documented in preclinical and clinical setting, the prolonged culture time required to develop an implantable device is associated with phenotypic drift and/or cell senescence. Herein, we demonstrate that macromolecular crowding significantly enhances extracellular matrix deposition in human bone marrow mesenchymal stem cell culture at both 20% and 2% oxygen tension. Although hypoxia inducible factor - 1α was activated at 2% oxygen tension, increased extracellular matrix synthesis was not observed. The expression of surface markers and transcription factors was not affected as a function of oxygen tension and macromolecular crowding. The multilineage potential was also maintained, albeit adipogenic differentiation was significantly reduced in low oxygen tension cultures, chondrogenic differentiation was significantly increased in macromolecularly crowded cultures and osteogenic differentiation was not affected as a function of oxygen tension and macromolecular crowding. Collectively, these data pave the way for the development of bottom-up tissue equivalents based on physiologically relevant developmental processes. PMID:27478033

  13. Macromolecular crowding meets oxygen tension in human mesenchymal stem cell culture - A step closer to physiologically relevant in vitro organogenesis

    NASA Astrophysics Data System (ADS)

    Cigognini, Daniela; Gaspar, Diana; Kumar, Pramod; Satyam, Abhigyan; Alagesan, Senthilkumar; Sanz-Nogués, Clara; Griffin, Matthew; O’Brien, Timothy; Pandit, Abhay; Zeugolis, Dimitrios I.

    2016-08-01

    Modular tissue engineering is based on the cells’ innate ability to create bottom-up supramolecular assemblies with efficiency and efficacy still unmatched by man-made devices. Although the regenerative potential of such tissue substitutes has been documented in preclinical and clinical setting, the prolonged culture time required to develop an implantable device is associated with phenotypic drift and/or cell senescence. Herein, we demonstrate that macromolecular crowding significantly enhances extracellular matrix deposition in human bone marrow mesenchymal stem cell culture at both 20% and 2% oxygen tension. Although hypoxia inducible factor - 1α was activated at 2% oxygen tension, increased extracellular matrix synthesis was not observed. The expression of surface markers and transcription factors was not affected as a function of oxygen tension and macromolecular crowding. The multilineage potential was also maintained, albeit adipogenic differentiation was significantly reduced in low oxygen tension cultures, chondrogenic differentiation was significantly increased in macromolecularly crowded cultures and osteogenic differentiation was not affected as a function of oxygen tension and macromolecular crowding. Collectively, these data pave the way for the development of bottom-up tissue equivalents based on physiologically relevant developmental processes.

  14. Linear chain tensioning of moored production vessels

    SciTech Connect

    Peters, B. )

    1993-04-01

    As need for development of marginal and deepwater oil fields grows, demand increases for floating production vessels (FPVs) such as floating production, storage and offloading (FPSO) units; spread-moored production semi-submersibles; and turret-moored production vessels. The FPV may be purpose-built; or an existing vessel such as an exploration drilling semi-sub or ship-shape vessel may be modified to suit the purpose. In either case, requirements for tensioning systems for the mooring lines on the FPV are quite unique, and are not without the potential for problems when traditional chain windlasses or wire rope systems are employed. This two-part article discusses the range of available technologies and systems for tensioning mooring lines on FPVs. It examines problems of size, weight and safety associated with some available designs; and it considers in detail a specific family of new units. Part 1, presented here, discusses the FPV market, worldwide potential locations and different requirements and evolution of the linear puller concept. The three principal types of chain jack systems - hollow ram, single cylinder and twin cylinders - are introduced and illustrated. And advantages of this relatively new form of passive mooring tensioning are outlined.

  15. Low-oxygen tensions found in Salmonella-infected gut tissue boost Salmonella replication in macrophages by impairing antimicrobial activity and augmenting Salmonella virulence.

    PubMed

    Jennewein, Jonas; Matuszak, Jasmin; Walter, Steffi; Felmy, Boas; Gendera, Kathrin; Schatz, Valentin; Nowottny, Monika; Liebsch, Gregor; Hensel, Michael; Hardt, Wolf-Dietrich; Gerlach, Roman G; Jantsch, Jonathan

    2015-12-01

    In Salmonella infection, the Salmonella pathogenicity island-2 (SPI-2)-encoded type three secretion system (T3SS2) is of key importance for systemic disease and survival in host cells. For instance, in the streptomycin-pretreated mouse model SPI-2-dependent Salmonella replication in lamina propria CD11c(-)CXCR1(-) monocytic phagocytes/macrophages (MΦ) is required for the development of colitis. In addition, containment of intracellular Salmonella in the gut critically depends on the antimicrobial effects of the phagocyte NADPH oxidase (PHOX), and possibly type 2 nitric oxide synthase (NOS2). For both antimicrobial enzyme complexes, oxygen is an essential substrate. However, the amount of available oxygen upon enteroinvasive Salmonella infection in the gut tissue and its impact on Salmonella-MΦ interactions was unknown. Therefore, we measured the gut tissue oxygen levels in a model of Salmonella enterocolitis using luminescence two-dimensional in vivo oxygen imaging. We found that gut tissue oxygen levels dropped from ∼78 Torr (∼11% O2) to values of ∼16 Torr (∼2% O2) during infection. Because in vivo virulence of Salmonella depends on the Salmonella survival in MΦ, Salmonella-MΦ interaction was analysed under such low oxygen values. These experiments revealed an increased intracellular replication and survival of wild-type and t3ss2 non-expressing Salmonella. These findings were paralleled by blunted nitric oxide and reactive oxygen species (ROS) production and reduced Salmonella ROS perception. In addition, hypoxia enhanced SPI-2 transcription and translocation of SPI-2-encoded virulence protein. Neither pharmacological blockade of PHOX and NOS2 nor impairment of T3SS2 virulence function alone mimicked the effect of hypoxia on Salmonella replication under normoxic conditions. However, if t3ss2 non-expressing Salmonella were used, hypoxia did not further enhance Salmonella recovery in a PHOX and NOS2-deficient situation. Hence, these data suggest that

  16. Collapse of Corroded Pipelines under Combined Tension and External Pressure

    PubMed Central

    Ye, Hao; Yan, Sunting; Jin, Zhijiang

    2016-01-01

    In this work, collapse of corroded pipeline under combined external pressure and tension is investigated through numerical method. Axially uniform corrosion with symmetric imperfections is firstly considered. After verifying with existing experimental results, the finite element model is used to study the effect of tension on collapse pressure. An extensive parametric study is carried out using Python script and FORTRAN subroutine to investigate the influence of geometric parameters on the collapse behavior under combined loads. The results are used to develop an empirical equation for estimating the collapse pressure under tension. In addition, the effects of loading path, initial imperfection length, yielding anisotropy and corrosion defect length on the collapse behavior are also investigated. It is found that tension has a significant influence on collapse pressure of corroded pipelines. Loading path and anisotropic yielding are also important factors affecting the collapse behavior. For pipelines with relatively long corrosion defect, axially uniform corrosion models could be used to estimate the collapse pressure. PMID:27111544

  17. Development of novel active transport membrande devices

    SciTech Connect

    Laciak, D.V.

    1994-11-01

    Air Products has undertaken a research program to fabricate and evaluate gas separation membranes based upon promising ``active-transport`` (AT) materials recently developed in our laboratories. Active Transport materials are ionic polymers and molten salts which undergo reversible interaction or reaction with ammonia and carbon dioxide. The materials are useful for separating these gases from mixtures with hydrogen. Moreover, AT membranes have the unique property of possessing high permeability towards ammnonia and carbon dioxide but low permeability towards hydrogen and can thus be used to permeate these components from a gas stream while retaining hydrogen at high pressure.

  18. Snapping mechanical metamaterials under tension.

    PubMed

    Rafsanjani, Ahmad; Akbarzadeh, Abdolhamid; Pasini, Damiano

    2015-10-21

    A snapping mechanical metamaterial is designed, which exhibits a sequential snap-through behavior under tension. The tensile response of this mechanical metamaterial can be altered by tuning the architecture of the snapping segments to achieve a range of nonlinear mechanical responses, including monotonic, S-shaped, plateau, and non-monotonic snap-through behavior.

  19. Researching with Children: Ethical Tensions

    ERIC Educational Resources Information Center

    Dockett, Sue; Einarsdottir, Johanna; Perry, Bob

    2009-01-01

    There is a need to reflect on both the processes and outcomes of the range of approaches aimed at promoting children's engagement in research, with the specific intent of listening to children's voices. This article considers some of the ethical tensions we have experienced when engaging children in research about their prior-to-school and school…

  20. Changes in passive tension of muscle in humans and animals after eccentric exercise

    PubMed Central

    Whitehead, N P; Weerakkody, N S; Gregory, J E; Morgan, D L; Proske, U

    2001-01-01

    This is a report of experiments on ankle extensor muscles of human subjects and a parallel series on the medial gastrocnemius of the anaesthetised cat, investigating the origin of the rise in passive tension after a period of eccentric exercise. Subjects exercised their triceps surae of one leg eccentrically by walking backwards on an inclined, forward-moving treadmill. Concentric exercise required walking forwards on a backwards-moving treadmill. For all subjects the other leg acted as a control. Immediately after both eccentric and concentric exercise there was a significant drop in peak active torque, but only after eccentric exercise was this accompanied by a shift in optimum angle for torque generation and a rise in passive torque. In the eccentrically exercised group some swelling and soreness developed but not until 24 h post-exercise. In the animal experiments the contracting muscle was stretched by 6 mm at 50 mm s−1 over a length range symmetrical about the optimum length for tension generation. Measurements of passive tension were made before and after the eccentric contractions, using small stretches to a range of muscle lengths, or with large stretches covering the full physiological range. After 150 eccentric contractions, passive tension was significantly elevated over most of the range of lengths. Measurements of work absorption during stretch-release cycles showed significant increases after the contractions. It is suggested that the rise in passive tension in both human and animal muscles after eccentric contractions is the result of development of injury contractures in damaged muscle fibres. PMID:11389215

  1. Myosin I contributes to the generation of resting cortical tension.

    PubMed

    Dai, J; Ting-Beall, H P; Hochmuth, R M; Sheetz, M P; Titus, M A

    1999-08-01

    The amoeboid myosin I's are required for cellular cortical functions such as pseudopod formation and macropinocytosis, as demonstrated by the finding that Dictyostelium cells overexpressing or lacking one or more of these actin-based motors are defective in these processes. Defects in these processes are concomitant with changes in the actin-filled cortex of various Dictyostelium myosin I mutants. Given that the amoeboid myosin I's possess both actin- and membrane-binding domains, the mutant phenotypes could be due to alterations in the generation and/or regulation of cell cortical tension. This has been directly tested by analyzing mutant Dictyostelium that either lacks or overexpresses various myosin I's, using micropipette aspiration techniques. Dictyostelium cells lacking only one myosin I have normal levels of cortical tension. However, myosin I double mutants have significantly reduced (50%) cortical tension, and those that mildly overexpress an amoeboid myosin I exhibit increased cortical tension. Treatment of either type of mutant with the lectin concanavalin A (ConA) that cross-links surface receptors results in significant increases in cortical tension, suggesting that the contractile activity of these myosin I's is not controlled by this stimulus. These results demonstrate that myosin I's work cooperatively to contribute substantially to the generation of resting cortical tension that is required for efficient cell migration and macropinocytosis.

  2. A pulling tension calculation program which allows coefficient of friction to vary continuously with cable sidewall pressure

    SciTech Connect

    Fee, J.M.

    1994-12-31

    A cable pulling tension calculation software program is developed which draws friction coefficients from a curve input by the user. Examples show how predicted tension and sidewall pressure vary with a coefficient of friction dependence on cable normal pressure. The software is intended as a ``what-if`` tool to help insulation planners develop better approximations of cable pulling tension.

  3. Stress and Androgen Activity During Fetal Development

    PubMed Central

    Swan, Shanna H.

    2015-01-01

    Prenatal stress is known to alter hypothalamic-pituitary-adrenal axis activity, and more recent evidence suggests that it may also affect androgen activity. In animal models, prenatal stress disrupts the normal surge of testosterone in the developing male, whereas in females, associations differ by species. In humans, studies show that (1) associations between prenatal stress and child outcomes are often sex-dependent, (2) prenatal stress predicts several disorders with notable sex differences in prevalence, and (3) prenatal exposure to stressful life events may be associated with masculinized reproductive tract development and play behavior in girls. In this minireview, we examine the existing literature on prenatal stress and androgenic activity and present new, preliminary data indicating that prenatal stress may also modify associations between prenatal exposure to diethylhexyl phthalate, (a synthetic, antiandrogenic chemical) and reproductive development in infant boys. Taken together, these data support the hypothesis that prenatal exposure to both chemical and nonchemical stressors may alter sex steroid pathways in the maternal-placental-fetal unit and ultimately alter hormone-dependent developmental endpoints. PMID:26241065

  4. Development of a lightning activity nowcasting tool

    NASA Astrophysics Data System (ADS)

    Karagiannidis, Athanassios; Lagouvardos, Kostas; Kotroni, Vassiliki

    2015-04-01

    Electrical phenomena inside thunderstorm clouds are a significant threat to numerous activities. Summertime convective activity is usually associated to local thermal instability, which is hard to predict using numerical weather prediction models. Despite their relatively small areal extend, these thunderstorms can be violent, resulting to infrastructure damage and loss of life. In the frame of TALOS project the National Observatory of Athens has developed a lightning activity nowcasting tool. This tool uses as sole inputs: (i) real time infrared Meteosat Second Generation (MSG) imagery and (ii) real time flashes provided by the VLF lightning detection system ZEUS, which is operated by the National Observatory of Athens. The MSG SEVIRI 10.8 and 6.2μm channels data are utilized to produce 3 Interest Fields (IFs). These fields are the TB10.8 brightness temperature (indicative of the cloud top glaciation), the TB6.2-TB10.8 difference (indicative of the cloud depth) and the TB10.8 15 minute trend, which will be referenced as "TB10.8trend" (indicative of the cloud growth rate). The latter is defined as the difference between two successive 15 minutes images of the TB10.8. When a predefined threshold value is surpassed, the delimited area is considered to be favorable for lightning activity. A statistical procedure is employed to identify the optimum threshold values for the three IFs, based on the performance of each one. The assessment of their efficiency showed that these three IFs can be used independently as predictors of lightning activity. However, in an effort to improve the tool's efficiency a combined estimation is performed. When all three IFs agree that lightning activity is expected over an area, then a Warning Level 3 (WL3) is issued. When 2 or 1 IFs indicate upcoming activity then a WL2 or WL1 is issued. The assessment of the efficiency of the combined IF tool showed that the combined estimation is more skillful than the individual IFs estimations. In a

  5. Passive tension in cardiac muscle: contribution of collagen, titin, microtubules, and intermediate filaments.

    PubMed Central

    Granzier, H L; Irving, T C

    1995-01-01

    The passive tension-sarcomere length relation of rat cardiac muscle was investigated by studying passive (or not activated) single myocytes and trabeculae. The contribution of collagen, titin, microtubules, and intermediate filaments to tension and stiffness was investigated by measuring (1) the effects of KCl/KI extraction on both trabeculae and single myocytes, (2) the effect of trypsin digestion on single myocytes, and (3) the effect of colchicine on single myocytes. It was found that over the working range of sarcomeres in the heart (lengths approximately 1.9-2.2 microns), collagen and titin are the most important contributors to passive tension with titin dominating at the shorter end of the working range and collagen at longer lengths. Microtubules made a modest contribution to passive tension in some cells, but on average their contribution was not significant. Finally, intermediate filaments contributed about 10% to passive tension of trabeculae at sarcomere lengths from approximately 1.9 to 2.1 microns, and their contribution dropped to only a few percent at longer lengths. At physiological sarcomere lengths of the heart, cardiac titin developed much higher tensions (> 20-fold) than did skeletal muscle titin at comparable lengths. This might be related to the finding that cardiac titin has a molecular mass of 2.5 MDa, 0.3-0.5 MDa smaller than titin of mammalian skeletal muscle, which is predicted to result in a much shorter extensible titin segment in the I-band of cardiac muscle. Passive stress plotted versus the strain of the extensible titin segment showed that the stress-strain relationships are similar in cardiac and skeletal muscle. The difference in passive stress between cardiac and skeletal muscle at the sarcomere level predominantly resulted from much higher strains of the I-segment of cardiac titin at a given sarcomere length. By expressing a smaller titin isoform, without changing the properties of the molecule itself, cardiac muscle is able to

  6. Nano-mechanical characterization of tension-sensitive helix bundles in talin rod.

    PubMed

    Maki, Koichiro; Nakao, Nobuhiko; Adachi, Taiji

    2017-03-04

    Tension-induced exposure of a cryptic signaling binding site is one of the most fundamental mechanisms in molecular mechanotransduction. Helix bundles in rod domains of talin, a tension-sensing protein at focal adhesions, unfurl under tension to expose cryptic vinculin binding sites. Although the difference in their mechanical stabilities would determine which helix bundle is tension-sensitive, their respective mechanical behaviors under tension have not been characterized. In this study, we evaluated the mechanical behaviors of residues 486-654 and 754-889 of talin, which form helix bundles with low and high tension-sensitivity, by employing AFM nano-tensile testing. As a result, residues 754-889 exhibited lower unfolding energy for complete unfolding than residues 486-654. In addition, we found that residues 754-889 transition into intermediate conformations under lower tension than residues 486-654. Furthermore, residues 754-889 showed shorter persistence length in the intermediate conformation than residues 486-654, suggesting that residues 754-889 under tension exhibit separated α-helices, while residues 486-654 assume a compact conformation with inter-helix interactions. Therefore, we suggest that residues 754-889 of talin work as a tension-sensitive domain to recruit vinculin at the early stage of focal adhesion development, while residues 486-654 contribute to rather robust tension-sensitivity by recruiting vinculin under high tension.

  7. Spatial foundation structures over no tension soil

    NASA Astrophysics Data System (ADS)

    Baratta, A.; Corbi, I.

    2005-12-01

    The problem of the stress distribution induced in the soil by a single circular foundation structure is approached in a three-dimensional analysis. Since the soil is typically made by not-cohesive materials, its behaviour is modelled by means of the not resisting tension (NRT) hypothesis, thus assuming that its very low resistance to tensile stresses can be completely neglected and that it keeps linearly elastic under pure compression. After developing the problem from a theoretical point of view on the basis of an energetic approach, a numerical application - which is able to reproduce the stress distribution induced by a circular foundation on the soil - is performed. Copyright

  8. Active Thermal Control System Development for Exploration

    NASA Technical Reports Server (NTRS)

    Westheimer, David

    2007-01-01

    All space vehicles or habitats require thermal management to maintain a safe and operational environment for both crew and hardware. Active Thermal Control Systems (ATCS) perform the functions of acquiring heat from both crew and hardware within a vehicle, transporting that heat throughout the vehicle, and finally rejecting that energy into space. Almost all of the energy used in a space vehicle eventually turns into heat, which must be rejected in order to maintain an energy balance and temperature control of the vehicle. For crewed vehicles, Active Thermal Control Systems are pumped fluid loops that are made up of components designed to perform these functions. NASA has been actively developing technologies that will enable future missions or will provide significant improvements over the state of the art technologies. These technologies have are targeted for application on the Crew Exploration Vehicle (CEV), or Orion, and a Lunar Surface Access Module (LSAM). The technologies that have been selected and are currently under development include: fluids that enable single loop ATCS architectures, a gravity insensitive vapor compression cycle heat pump, a sublimator with reduced sensitivity to feedwater contamination, an evaporative heat sink that can operate in multiple ambient pressure environments, a compact spray evaporator, and lightweight radiators that take advantage of carbon composites and advanced optical coatings.

  9. Effect of protein supplementation and presence of an antioxidant on the development of bovine zygotes in synthetic oviduct fluid medium under high or low oxygen tension.

    PubMed

    Lonergan, P; O'Kearney-Flynn, M; Boland, M P

    1999-06-01

    The aim of this study was to investigate the effect of protein supplementation of culture medium and the presence of a putative antioxidant on bovine zygote development under 5% (low) and 20% (high) O2. In Experiment 1, presumptive zygotes (n=992) were cultured in synthetic oviduct fluid (SOF) alone or supplemented with 3 mg/mL PVP, 3 mg/mL BSA (SOFB), and/or 10% FCS (SOFBF) in 5% CO2, 5% O2, 90% N2. In Experiment 2, zygotes (n=1916) were cultured in SOF, SOFB or SOFBF with or without taurine under high and low O2. In Experiment 1, presence of BSA or BSA plus FCS significantly increased the speed of development compared to SOF or SOF+PVP. Blastocyst quality was also improved, as evidenced by increased hatching rate and cell numbers. In Experiments 2, taurine had no effect on development irrespective of oxygen concentration or protein supplementation. In conclusion, the presence of protein in the culture medium and culture under reduced O2 significantly improved embryo development. Taurine had no effect on development.

  10. Surface Tension Confines Cryogenic Liquid

    NASA Technical Reports Server (NTRS)

    Castles, Stephen H.; Schein, Michael E.

    1989-01-01

    New type of Dewar provides passive, constant-temperature cryogenic cooling for scientific instruments under normal-to low-gravity conditions. Known as Surface-Tension-Contained Liquid Cryogen Cooler (STCLCC), keeps liquid cryogen in known location inside the Dewar by trapping liquid inside spongelike material. Unique sponge material fills most of volume of inner tank. Sponge is all-silica, open-cell material similar to that used for Space Shuttle thermal-protection tiles.

  11. Perceiving the affordance of string tension for power strokes in badminton: expertise allows effective use of all string tensions.

    PubMed

    Zhu, Qin

    2013-01-01

    Affordances mean opportunities for action. These affordances are important for sports performance and relevant to the abilities developed by skilled athletes. In racquet sports such as badminton, different players prefer widely different string tension because it is believed to provide opportunities for effective strokes. The current study examined whether badminton players can perceive the affordance of string tension for power strokes and whether the perception of affordance itself changed as a function of skill level. The results showed that string tension constrained the striking performance of both novice and recreational players, but not of expert players. When perceptual capability was assessed, perceptual mode did not affect perception of the optimal string tension. Skilled players successfully perceived the affordance of string tension, but only experts were concerned about saving energy. Our findings demonstrated that perception of the affordance of string tension in badminton was determined by action abilities. Furthermore, experts could adjust the action to maintain a superior level of performance based on the perception of affordance.

  12. Defining the role of oxygen tension in human neural progenitor fate.

    PubMed

    Xie, Yuan; Zhang, Jin; Lin, Ying; Gaeta, Xavier; Meng, Xiangzhi; Wisidagama, Dona R R; Cinkornpumin, Jessica; Koehler, Carla M; Malone, Cindy S; Teitell, Michael A; Lowry, William E

    2014-11-11

    Hypoxia augments human embryonic stem cell (hESC) self-renewal via hypoxia-inducible factor 2α-activated OCT4 transcription. Hypoxia also increases the efficiency of reprogramming differentiated cells to a pluripotent-like state. Combined, these findings suggest that low O2 tension would impair the purposeful differentiation of pluripotent stem cells. Here, we show that low O2 tension and hypoxia-inducible factor (HIF) activity instead promote appropriate hESC differentiation. Through gain- and loss-of-function studies, we implicate O2 tension as a modifier of a key cell fate decision, namely whether neural progenitors differentiate toward neurons or glia. Furthermore, our data show that even transient changes in O2 concentration can affect cell fate through HIF by regulating the activity of MYC, a regulator of LIN28/let-7 that is critical for fate decisions in the neural lineage. We also identify key small molecules that can take advantage of this pathway to quickly and efficiently promote the development of mature cell types.

  13. Mechanical sensitivity of Piezo1 ion channels can be tuned by cellular membrane tension

    PubMed Central

    Lewis, Amanda H; Grandl, Jörg

    2015-01-01

    Piezo1 ion channels mediate the conversion of mechanical forces into electrical signals and are critical for responsiveness to touch in metazoans. The apparent mechanical sensitivity of Piezo1 varies substantially across cellular environments, stimulating methods and protocols, raising the fundamental questions of what precise physical stimulus activates the channel and how its stimulus sensitivity is regulated. Here, we measured Piezo1 currents evoked by membrane stretch in three patch configurations, while simultaneously visualizing and measuring membrane geometry. Building on this approach, we developed protocols to minimize resting membrane curvature and tension prior to probing Piezo1 activity. We find that Piezo1 responds to lateral membrane tension with exquisite sensitivity as compared to other mechanically activated channels and that resting tension can drive channel inactivation, thereby tuning overall mechanical sensitivity of Piezo1. Our results explain how Piezo1 can function efficiently and with adaptable sensitivity as a sensor of mechanical stimulation in diverse cellular contexts. DOI: http://dx.doi.org/10.7554/eLife.12088.001 PMID:26646186

  14. Analysis of the different slip systems activated by tension in a {alpha}/{beta} titanium alloy in relation with local crystallographic orientation

    SciTech Connect

    Bridier, F.; Villechaise, P. . E-mail: p.villechaise@lmpm.ensma.fr; Mendez, J.

    2005-02-01

    The gliding modes of a duplex Ti-6Al-4V titanium alloy were investigated through in situ (scanning electron microscopy) tensile tests. A method based on electron back-scattering diffraction (EBSD) measurements was used to identify activated slip systems. The approach applied to a large number of grains allowed a statistical analysis of the nature (basal, prismatic, pyramidal) and distribution of the slip systems according to the crystallographic texture. A discussion concerning the pertinence of Schmid's law to explain the occurrence and succession of slip events is then proposed. The domain in favor of each type of slip system is finally presented by using inverse pole figures mapped with Schmid's factor iso-curves.

  15. Aspirations and Tensions in Developing International Mindedness: Case Study of Two Students in an IB School in an Indian Ocean Island Nation

    ERIC Educational Resources Information Center

    Poonoosamy, Mico

    2016-01-01

    International mindedness is considered by many educational researchers and organizations as a determining feature in international education. This article used data as part of a PhD case study inquiry to explore how international mindedness is developed by two students in an IB school in an Indian Ocean Island Nation. Through a qualitative…

  16. Development of entrepreneurial activity in nurse education.

    PubMed

    Roberts, Paula; Bridgwood, Bernadeta; Jester, Rebecca

    The provision of health care and healthcare education in the UK is undergoing rapid change and development, and is subject to intense market forces. A reduction in the amount of money being spent on nurses' education and training, together with changes in working practices in health care, are affecting the provision of healthcare education significantly. This article gives an overview of the changes influencing providers of pre and post-registration healthcare education, and describes how education providers are generating income through enterprise activity.

  17. How do mechanosensitive channels sense membrane tension?

    PubMed

    Rasmussen, Tim

    2016-08-15

    Mechanosensitive (MS) channels provide protection against hypo-osmotic shock in bacteria whereas eukaryotic MS channels fulfil a multitude of important functions beside osmoregulation. Interactions with the membrane lipids are responsible for the sensing of mechanical force for most known MS channels. It emerged recently that not only prokaryotic, but also eukaryotic, MS channels are able to directly sense the tension in the membrane bilayer without any additional cofactor. If the membrane is solely viewed as a continuous medium with specific anisotropic physical properties, the sensitivity towards tension changes can be explained as result of the hydrophobic coupling between membrane and transmembrane (TM) regions of the channel. The increased cross-sectional area of the MS channel in the active conformation and elastic deformations of the membrane close to the channel have been described as important factors. However, recent studies suggest that molecular interactions of lipids with the channels could play an important role in mechanosensation. Pockets in between TM helices were identified in the MS channel of small conductance (MscS) and YnaI that are filled with lipids. Less lipids are present in the open state of MscS than the closed according to MD simulations. Thus it was suggested that exclusion of lipid fatty acyl chains from these pockets, as a consequence of increased tension, would trigger gating. Similarly, in the eukaryotic MS channel TRAAK it was found that a lipid chain blocks the conducting path in the closed state. The role of these specific lipid interactions in mechanosensation are highlighted in this review.

  18. Cyfip1 Regulates Presynaptic Activity during Development

    PubMed Central

    Hsiao, Kuangfu; Harony-Nicolas, Hala; Buxbaum, Joseph D.

    2016-01-01

    Copy number variations encompassing the gene encoding Cyfip1 have been associated with a variety of human diseases, including autism and schizophrenia. Here we show that juvenile mice hemizygous for Cyfip1 have altered presynaptic function, enhanced protein translation, and increased levels of F-actin. In developing hippocampus, reduced Cyfip1 levels serve to decrease paired pulse facilitation and increase miniature EPSC frequency without a change in amplitude. Higher-resolution examination shows these changes to be caused primarily by an increase in presynaptic terminal size and enhanced vesicle release probability. Short hairpin-mediated knockdown of Cyfip1 coupled with expression of mutant Cyfip1 proteins indicates that the presynaptic alterations are caused by dysregulation of the WAVE regulatory complex. Such dysregulation occurs downstream of Rac1 as acute exposure to Rac1 inhibitors rescues presynaptic responses in culture and in hippocampal slices. The data serve to highlight an early and essential role for Cyfip1 in the generation of normally functioning synapses and suggest a means by which changes in Cyfip1 levels could impact the generation of neural networks and contribute to abnormal and maladaptive behaviors. SIGNIFICANCE STATEMENT Several developmental brain disorders have been associated with gene duplications and deletions that serve to increase or decrease levels of encoded proteins. Cyfip1 is one such protein, but the role it plays in brain development is poorly understood. We asked whether decreased Cyfip1 levels altered the function of developing synapses. The data show that synapses with reduced Cyfip1 are larger and release neurotransmitter more rapidly. These effects are due to Cyfip1's role in actin polymerization and are reversed by expression of a Cyfip1 mutant protein retaining actin regulatory function or by inhibiting Rac1. Thus, Cyfip1 has a more prominent early role regulating presynaptic activity during a stage of development when

  19. Strong evidence of surface tension reduction in microscopic aqueous droplets

    NASA Astrophysics Data System (ADS)

    Ruehl, C. R.; Chuang, P. Y.; Nenes, A.; Cappa, C. D.; Kolesar, K. R.; Goldstein, A. H.

    2012-12-01

    The ability of airborne particles to take up water may be enhanced by surface-active components, but the importance of this effect is controversial because direct measurement of the surface tension of microscopic droplets has not been possible. Here we infer droplet surface tension from water uptake measurements of mixed organic-inorganic particles at relative humidities just below saturation (99.3-99.9%). The surface tension of droplets formed on particles composed of NaCl and α-pinene ozonolysis products was reduced by 50-75%, but only when enough organic material was present to form a film on the droplet surface at least 0.8 nm thick. This study suggests that if atmospheric particles are predominantly (≳80%) composed of surface-active material, their influence on cloud properties and thus climate could be enhanced, and their atmospheric lifetimes could be reduced.

  20. Proprioception and tension receptors in crab limbs: student laboratory exercises.

    PubMed

    Majeed, Zana R; Titlow, Josh; Hartman, H Bernard; Cooper, Robin

    2013-10-24

    The primary purpose of these procedures is to demonstrate for teaching and research purposes how to record the activity of living primary sensory neurons responsible for proprioception as they are detecting joint position and movement, and muscle tension. Electrical activity from crustacean proprioceptors and tension receptors is recorded by basic neurophysiological instrumentation, and a transducer is used to simultaneously measure force that is generated by stimulating a motor nerve. In addition, we demonstrate how to stain the neurons for a quick assessment of their anatomical arrangement or for permanent fixation. Staining reveals anatomical organization that is representative of chordotonal organs in most crustaceans. Comparing the tension nerve responses to the proprioceptive responses is an effective teaching tool in determining how these sensory neurons are defined functionally and how the anatomy is correlated to the function. Three staining techniques are presented allowing researchers and instructors to choose a method that is ideal for their laboratory.

  1. Development of a topically active imiquimod formulation.

    PubMed

    Chollet, J L; Jozwiakowski, M J; Phares, K R; Reiter, M J; Roddy, P J; Schultz, H J; Ta, Q V; Tomai, M A

    1999-01-01

    The purpose of this work was to develop a topical formulation of imiquimod, a novel immune response modifier, to induce local cytokine production for the treatment of external genital and perianal warts. A pH-solubility profile and titration data were used to calculate a pKa of 7.3, indicative of a weak base. Solubility experiments were conducted to identify a solvent that dissolves imiquimod to achieve a 5% formulation concentration. Studies to select surfactants, preservatives, and viscosity-enhancing excipients to formulate an oil-in-water cream indicated that fatty acids were the preferred solvent for topical imiquimod formulations, and isostearic acid (ISA) was selected. A relationship existed between the fatty acid composition of four commercially available ISA sources and the solubility of imiquimod. A combination of polysorbate 60, sorbitan monostearate, and xanthan gum was used to produce a physically stable cream. The preservative system included parabens and benzyl alcohol to meet the USP criteria for preservative activity. An in vitro method was developed to demonstrate that imiquimod was released from the formulation. Topical application of the formulation induced local cytokine activity in mice.

  2. A prescriptive intergenerational-tension ageism scale: succession, identity, and consumption (SIC).

    PubMed

    North, Michael S; Fiske, Susan T

    2013-09-01

    We introduce a novel ageism scale, focusing on prescriptive beliefs concerning potential intergenerational tensions: active, envied resource succession, symbolic identity avoidance, and passive, shared-resource consumption (SIC). Four studies (2,010 total participants) were used to develop the scale. Exploratory factor analysis formed an initial 20-item, 3-factor solution (Study 1). The scale converges appropriately with other prejudice measures and diverges from other social control measures (Study 2). It diverges from antiyouth ageism (Study 3). The Study 4 experiment yielded both predictive and divergent validity apropos another ageism measure. Structural equation modeling confirmed model fit across all studies. Per an intergenerational-tension focus, younger people consistently scored the highest. As generational equity issues intensify, the scale provides a contemporary tool for current and future ageism research.

  3. A Prescriptive, Intergenerational-Tension Ageism Scale: Succession, Identity, and Consumption (SIC)

    PubMed Central

    North, Michael S.; Fiske, Susan T.

    2014-01-01

    We introduce a novel ageism scale, focusing on prescriptive beliefs concerning potential intergenerational tensions: active, envied resource Succession, symbolic Identity avoidance, and passive, shared-resource Consumption (SIC). Four studies (2,010 total participants) developed the scale. EFA formed an initial 20-item, three-factor solution (Study 1). The scale converges appropriately with other prejudice measures and diverges from other social control measures (Study 2). It diverges from anti-youth ageism (Study 3). Study 4’s experiment yielded both predictive and divergent validity apropos another ageism measure. Structural equation modeling confirmed model fit across all studies. Per an intergenerational-tension focus, younger people consistently scored the highest. As generational equity issues intensify, the scale provides a contemporary tool for current and future ageism research. PMID:23544391

  4. Development of Observational Activities for Introductory Astronomy

    NASA Astrophysics Data System (ADS)

    Marshall, Kevin; Wilson, J.

    2007-05-01

    During the spring of 2006 new laboratory activities were developed for introductory astronomy classes at Georgia State University. The purpose of these labs was to develop hands-on astronomy activates. We first purchased Project Star refracting telescope kits and spectrometer kits, and a Meade Deep Sky Imager CCD. The new materials were tried on a single lab section of 22 students. For comparison purposes a traditional lab section from the same large lecture class was selected as a control group. The students in the experimental group constructed the telescopes and measured their telescope’s, light gathering ability and its angular resolution and compared them to the human eye, and its magnification. The students also built spectrometers and learned how to use them identify different types of light sources such as Mercury vapor lights, high and low pressure sodium lights, fluorescent lights, and other typical light sources. Each student then performed a light pollution investigation of their neighborhood using the spectroscopes they had constructed. In addition all students used these spectroscopes to observe solar Fraunhofer lines. In lab students used a small Schmidt-Cassegrain telescope and the Meade Deep Sky Imager to take photos of objects inside the lab room. After this they took telescopic pictures of the sun and moon on several occasions. The students rally enjoyed most of these activities. Student in the experimental group had slightly higher final exam scores than the students in the control group. However, the drop rate for the control group was higher then the experimental group and so the statistical significance of the result could not be determined. The authors would like to thank the Partnership for Reform in Science and Mathematics (PRISM), funded by NSF, for providing a mini-grant to support this work.

  5. Tensioning device for a stretched membrane collector

    DOEpatents

    Murphy, L.M.

    1984-01-01

    Disclosed is a solar concentrating collector comprising an elestic membrane member for concentrating sunlight, a frame for holding the membrane member in plane and in tension, and a tensioning means for varying the tension of the membrane member. The tensioning means is disposed at the frame and is adapted to releasably attach the membrane member thereto. The tensioning means is also adapted to uniformly and symmetrically subject the membrane member to stretching forces such that membrane stresses produced thereby are distributed uniformly over a thickness of the membrane member and reciprocal twisting moments are substantially prevented from acting about said frame.

  6. Tensioning device for a stretched membrane collector

    DOEpatents

    Murphy, Lawrence M.

    1984-01-01

    Disclosed is a solar concentrating collector comprising an elastic membrane member for concentrating sunlight, a frame for holding the membrane member in plane and in tension, and a tensioning means for varying the tension of the membrane member. The tensioning means is disposed at the frame and is adapted to releasably attach the membrane member thereto. The tensioning means is also adapted to uniformly and symmetrically subject the membrane member to stretching forces such that membrane stresses produced thereby are distributed uniformly over a thickness of the membrane member and reciprocal twisting moments are substantially prevented from acting about said frame.

  7. 24 CFR 1003.203 - Special economic development activities.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Special economic development... Eligible Activities § 1003.203 Special economic development activities. A grantee may use ICDBG funds for special economic development activities in addition to other activities authorized in this subpart...

  8. 24 CFR 1003.203 - Special economic development activities.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 4 2011-04-01 2011-04-01 false Special economic development... Eligible Activities § 1003.203 Special economic development activities. A grantee may use ICDBG funds for special economic development activities in addition to other activities authorized in this subpart...

  9. 24 CFR 1003.203 - Special economic development activities.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 4 2014-04-01 2014-04-01 false Special economic development... Eligible Activities § 1003.203 Special economic development activities. A grantee may use ICDBG funds for special economic development activities in addition to other activities authorized in this subpart...

  10. Development of a Front Tracking Method for Two-Phase Micromixing of Incompressible Viscous Fluids with Interfacial Tension in Solvent Extraction

    SciTech Connect

    Zhou, Yijie; Lim, Hyun-Kyung; de Almeida, Valmor F; Navamita, Ray; Wang, Shuqiang; Glimm, James G; Li, Xiao-lin; Jiao, Xiangmin

    2012-06-01

    This progress report describes the development of a front tracking method for the solution of the governing equations of motion for two-phase micromixing of incompressible, viscous, liquid-liquid solvent extraction processes. The ability to compute the detailed local interfacial structure of the mixture allows characterization of the statistical properties of the two-phase mixture in terms of droplets, filaments, and other structures which emerge as a dispersed phase embedded into a continuous phase. Such a statistical picture provides the information needed for building a consistent coarsened model applicable to the entire mixing device. Coarsening is an undertaking for a future mathematical development and is outside the scope of the present work. We present here a method for accurate simulation of the micromixing dynamics of an aqueous and an organic phase exposed to intense centrifugal force and shearing stress. The onset of mixing is the result of the combination of the classical Rayleigh- Taylor and Kelvin-Helmholtz instabilities. A mixing environment that emulates a sector of the annular mixing zone of a centrifugal contactor is used for the mathematical domain. The domain is small enough to allow for resolution of the individual interfacial structures and large enough to allow for an analysis of their statistical distribution of sizes and shapes. A set of accurate algorithms for this application requires an advanced front tracking approach constrained by the incompressibility condition. This research is aimed at designing and implementing these algorithms. We demonstrate verification and convergence results for one-phase and unmixed, two-phase flows. In addition we report on preliminary results for mixed, two-phase flow for realistic operating flow parameters.

  11. [Perinatal innate immune activation and neuropsychological development].

    PubMed

    Nagai, Taku

    2013-08-01

    Development of animal models is a crucial issue in biological psychiatry for the search of novel drug targets as well as the screening of candidate compounds. Epidemiologic studies suggest that environmental insults, such as prenatal infection and perinatal complication, are involved in the development of schizophrenia. Recently, we have developed a novel mouse model of viral infection during the perinatal stage by injecting polyriboinosinic-polyribocytidilic acid (polyI:C) into neonatal mice. Neonatal treatment of mice with polyI:C, an inducer of innate immune responses via toll-like receptor 3, caused a significant increase in interferon-induced transmembrane protein 3 (IFITM3) levels in the astrocytes of the hippocampus, which resulted in long-lasting brain dysfunction, including cognitive and emotional impairments as well as a deficit in depolarization-evoked glutamate release in the hippocampus in adulthood. Neonatal polyI:C-induced neuronal impairments have not been observed in IFITM3-KO mice. These findings suggest that the induction of IFITM3 expression in astrocytes by the activation of the innate immune system during the early stages of neurodevelopment has non-cell autonomous effects that affect subsequent neurodevelopment, leading to neuropathological impairments and brain dysfunction, by impairing endocytosis in astrocytes.

  12. Visitor empowerment and the authority of science: Exploring institutionalized tensions in a science center

    NASA Astrophysics Data System (ADS)

    Loomis, Molly

    This research explored the relationships among societal, organizational, and visitor assumptions about learning in a science center. The study combined a sociocultural theory of learning with a constructivist theory of organizations to examine empirical links among the history of the Exploratorium (founded in 1969 and located in San Francisco, California), its organizational practices, and family activity at its exhibits. The study focused on three perspectives on science learning in a science center: (1) the societal perspective, which traced assumptions about science learning to the history of science centers; (2) the organizational perspective, which documented the ways that assumptions about science learning were manifested in historic museum exhibits; and (3) the family perspective, which documented the assumptions about science learning that characterized family activity at historic exhibits. All three perspectives uncovered a tension between the goals of supporting public empowerment on the one hand and preserving scientific authority on the other. Findings revealed this tension to be grounded in the social context of the organization's development, where ideas about promoting democracy and preserving the authority of science intersected. The tension was manifested in museum exhibits, which had as their task addressing the dual purposes of supporting all visitors, while also supporting committed visitors. The tension was also evident in the activity of families, who echoed sentiments about potential for their own empowerment but deferred to scientific authority. The study draws on critiques of a hidden curriculum in schools in order to explore the relationship between empowerment and authority in science centers, specifically as they are conveyed in the explicit and underlying missions of the Exploratorium. Findings suggest the need for science centers to engage in ongoing critical reflection and also lend empirical justification to the need for science

  13. Essential Tension: Specialization with Broad and General Training in Psychology

    ERIC Educational Resources Information Center

    Roberts, Michael C.

    2006-01-01

    The practice fields of psychology develop through specialization in training and education. The recognized specialties play a major role in developing new opportunities for professional psychology and providing quality services for the public. The essential tension comes from the balance of innovation and tradition and, in professional psychology,…

  14. Fluctuations in tension during contraction of single muscle fibers.

    PubMed Central

    Borejdo, J; Morales, M F

    1977-01-01

    We have searched for fluctuations in the steady-state tension developed by stimulated single muscle fibers. Such tension "noise" is expected to be present as a result of the statistical fluctuations in the number and/or state of myosin cross-bridges interacting with thin filament sites at any time. A sensitive electro-optical tension transducer capable of resolving the expected fluctuations in magnitude and frequency was constructed to search for the fluctuations. The noise was analyzed by computing the power spectra and amplitude of stochastic fluctuations in the photomultiplier counting rate, which was made proportional to muscle force. The optical system and electronic instrumentation together with the minicomputer software are described. Tensions were measured in single skinned glycerinated rabbit psoas muscle fibers in rigor and during contraction and relaxation. The results indicate the presence of fluctuations in contracting muscles and a complete absence of tension noise in eith rigor or relaxation. Also, a numerical method was developed to simulate the power spectra and amplitude of fluctuations, given the rate constants for association and dissociation of the cross-bridges and actin. The simulated power spectra and the frequency distributions observed experimentally are similar. PMID:922123

  15. How Somatic Adult Tissues Develop Organizer Activity.

    PubMed

    Vogg, Matthias C; Wenger, Yvan; Galliot, Brigitte

    2016-01-01

    The growth and patterning of anatomical structures from specific cellular fields in developing organisms relies on organizing centers that instruct surrounding cells to modify their behavior, namely migration, proliferation, and differentiation. We discuss here how organizers can form in adult organisms, a process of utmost interest for regenerative medicine. Animals like Hydra and planarians, which maintain their shape and fitness thanks to a highly dynamic homeostasis, offer a useful paradigm to study adult organizers in steady-state conditions. Beside the homeostatic context, these model systems also offer the possibility to study how organizers form de novo from somatic adult tissues. Both extracellular matrix remodeling and caspase activation play a key role in this transition, acting as promoters of organizer formation in the vicinity of the wound. Their respective roles and the crosstalk between them just start to be deciphered.

  16. Genotype tunes pancreatic ductal adenocarcinoma tissue tension to induce matricellular-fibrosis and tumor progression

    PubMed Central

    Laklai, Hanane; Miroshnikova, Yekaterina A.; Pickup, Michael W.; Collisson, Eric A.; Kim, Grace E.; Barrett, Alex S.; Hill, Ryan C.; Lakins, Johnathon N.; Schlaepfer, David D.; Mouw, Janna K.; LeBleu, Valerie S.; Roy, Nilotpal; Novitskiy, Sergey V.; Johansen, Julia S.; Poli, Valeria; Kalluri, Raghu; Iacobuzio-Donahue, Christine A.; Wood, Laura D.; Hebrok, Matthias; Hansen, Kirk; Moses, Harold L.; Weaver, Valerie M.

    2016-01-01

    Fibrosis compromises pancreatic ductal carcinoma (PDAC) treatment and contributes to patient mortality yet anti-stromal therapies are controversial. We found that human PDACs with impaired epithelial transforming growth factor β (TGF-β) signaling have elevated epithelial Stat3 activity and develop a stiffer, matricellular-enriched fibrosis associated with high epithelial tension and shorter patient survival. In several Kras-driven mouse models, both the loss of TGF-β signaling and elevated β1-integrin mechanosignaling engaged a positive feedback loop whereby Stat3 signaling promotes tumor progression by increasing matricellular fibrosis and tissue tension. In contrast, epithelial Stat3 ablation attenuated tumor progression by reducing the stromal stiffening and epithelial contractility induced by loss of TGF-β signaling. In PDAC patient biopsies, higher matricellular protein and activated Stat3 associated with SMAD4 mutation and shorter survival. The findings implicate epithelial tension and matricellular fibrosis in the aggressiveness of SMAD4 mutant pancreatic tumors, and highlight Stat3 and mechanics as key drivers of this phenotype. PMID:27089513

  17. Non-Invasive Tension Measurement Devices for Parachute Cordage

    NASA Technical Reports Server (NTRS)

    Litteken, Douglas A.; Daum, Jared S.

    2016-01-01

    The need for lightweight and non-intrusive tension measurements has arisen alongside the development of high-fidelity computer models of textile and fluid dynamics. In order to validate these computer models, data must be gathered in the operational environment without altering the design, construction, or performance of the test article. Current measurement device designs rely on severing a cord and breaking the load path to introduce a load cell. These load cells are very reliable, but introduce an area of high stiffness in the load path, directly affecting the structural response, adding excessive weight, and possibly altering the dynamics of the parachute during a test. To capture the required data for analysis validation without affecting the response of the system, non-invasive measurement devices have been developed and tested by NASA. These tension measurement devices offer minimal impact to the mass, form, fit, and function of the test article, while providing reliable, axial tension measurements for parachute cordage.

  18. Whole muscle length-tension relationships are accurately modeled as scaled sarcomeres in rabbit hindlimb muscles.

    PubMed

    Winters, Taylor M; Takahashi, Mitsuhiko; Lieber, Richard L; Ward, Samuel R

    2011-01-04

    An a priori model of the whole active muscle length-tension relationship was constructed utilizing only myofilament length and serial sarcomere number for rabbit tibialis anterior (TA), extensor digitorum longus (EDL), and extensor digitorum II (EDII) muscles. Passive tension was modeled with a two-element Hill-type model. Experimental length-tension relations were then measured for each of these muscles and compared to predictions. The model was able to accurately capture the active-tension characteristics of experimentally-measured data for all muscles (ICC=0.88 ± 0.03). Despite their varied architecture, no differences in predicted versus experimental correlations were observed among muscles. In addition, the model demonstrated that excursion, quantified by full-width-at-half-maximum (FWHM) of the active length-tension relationship, scaled linearly (slope=0.68) with normalized muscle fiber length. Experimental and theoretical FWHM values agreed well with an intraclass correlation coefficient of 0.99 (p<0.001). In contrast to active tension, the passive tension model deviated from experimentally-measured values and thus, was not an accurate predictor of passive tension (ICC=0.70 ± 0.07). These data demonstrate that modeling muscle as a scaled sarcomere provides accurate active functional but not passive functional predictions for rabbit TA, EDL, and EDII muscles and call into question the need for more complex modeling assumptions often proposed.

  19. Length-tension relationships of sub-epicardial and sub-endocardial single ventricular myocytes from rat and ferret hearts.

    PubMed

    Cazorla, O; Le Guennec, J Y; White, E

    2000-05-01

    In vivo the sub-epicardial myocardium (EPI) and sub-endocardial myocardium (ENDO) operate over different ranges of sarcomere length (SL). However, it has not been previously shown whether EPI and ENDO work upon different ranges of the same or differing length-tension curves. We have compared the SL-tension relationship of intact, single ventricular EPI and ENDO myocytes from rat and ferret hearts. Cells were attached to carbon fibres of known compliance in order to stretch them and to record force at rest (passive tension) and during contractions (active tension). In both species, ENDO cells were significantly stiffer (i.e. had steeper SL-passive tension relationships) than EPI cells. Ferret ENDO cells had significantly steeper SL-active tension relationships than EPI cells; rat cells tended to behave similarly but no significant regional differences in active properties were observed. There were no inter-species differences in the active and passive properties of EPI cells, but ferret ENDO cells displayed significantly steeper passive and active SL-tension relationships than rat ENDO. We conclude that in vivo, ferret EPI and ENDO myocytes will function over different ranges of different SL-tension curves. There is a close relationship between SL and active tension (the Frank-Starling law of the heart), and our observations suggest that regional differences in the response to ventricular dilation will depend on both the change in SL and differing regional slopes of the SL-active tension curves.

  20. Tension-compression-tension tertiary twins in coarse-grained polycrystalline pure magnesium at room temperature

    SciTech Connect

    Yu, Qin; Jiang, Yanyao; Wang, Jian

    2015-04-07

    Using electron backscatter diffraction, the microstructural features of tension–compression–tension (T–C–T) tertiary twins are studied in coarse-grained pure polycrystalline magnesium subjected to monotonic compression along the extrusion direction in ambient air. T–C–T tertiary twins are developed due to the formation of a compression–tension double twin inside a primary tension twin. All the observed T–C–T twin variants are of TiCjTj type. TiCi+1Ti+1 (or TiCi–1Ti–1) variants are observed more frequently than TiCi+2Ti+2 (or TiCi–2Ti–2) variants. Moreover, the number of tertiary twin lamellae increases with the applied compressive strain.

  1. Axelrod's model with surface tension

    NASA Astrophysics Data System (ADS)

    Pace, Bruno; Prado, Carmen P. C.

    2014-06-01

    In this work we propose a subtle change in Axelrod's model for the dissemination of culture. The mechanism consists of excluding from the set of potentially interacting neighbors those that would never possibly exchange. Although the alteration proposed does not alter the state space topologically, it yields significant qualitative changes, specifically the emergence of surface tension, driving the system in some cases to metastable states. The transient behavior is considerably richer, and cultural regions become stable leading to the formation of different spatiotemporal patterns. A metastable "glassy" phase emerges between the globalized phase and the disordered, multicultural phase.

  2. Solute clustering and interfacial tension

    NASA Astrophysics Data System (ADS)

    Larson, M. A.; Garside, John

    1986-07-01

    The effect of surface curvature on surface tension has been included in the theory of homogeneous nucleation to show that, under certain conditions, cluster formation results in a decrease in Gibb's free energy. This cluster formation is thus a spontaneous event and a quasi-equilibrium concentration of clusters of narrow size range may then exist in supersaturated solutions. Previous experimental work suggests the existence of solute clusters in a variety of aqueous solutions. The implications for crystal nucleation and growth theory are discussed.

  3. Effects of eugenol on resting tension of rat atria.

    PubMed

    Olivoto, R R; Damiani, C E N; Kassouf Silva, I; Lofrano-Alves, M S; Oliveira, M A; Fogaça, R T H

    2014-04-01

    In cardiac and skeletal muscle, eugenol (μM range) blocks excitation-contraction coupling. In skeletal muscle, however, larger doses of eugenol (mM range) induce calcium release from the sarcoplasmic reticulum. The effects of eugenol are therefore dependent on its concentration. In this study, we evaluated the effects of eugenol on the contractility of isolated, quiescent atrial trabeculae from male Wistar rats (250-300 g; n=131) and measured atrial ATP content. Eugenol (1, 3, 5, 7, and 10 mM) increased resting tension in a dose-dependent manner. Ryanodine [100 µM; a specific ryanodine receptor (RyR) blocker] and procaine (30 mM; a nonspecific RyR blocker) did not block the increased resting tension induced by eugenol regardless of whether extracellular calcium was present. The myosin-specific inhibitor 2,3-butanedione monoxime (BDM), however, reversed the increase in resting tension induced by eugenol. In Triton-skinned atrial trabeculae, in which all membranes were solubilized, eugenol did not change resting tension, maximum force produced, or the force vs pCa relationship (pCa=-log [Ca2+]). Given that eugenol reduced ATP concentration, the increase in resting tension observed in this study may have resulted from cooperative activation of cardiac thin filaments by strongly attached cross-bridges (rigor state).

  4. Spontaneous Late Intraocular Lens and Capsule Tension Ring Dislocation

    PubMed Central

    Koçak Altıntaş, Ayşe Gül; Omay, Aslıhan Esra; Çelik, Selda

    2017-01-01

    In this report, three cases with pseudoexfoliation (PEX) and advanced age with spontaneous intraocular lens (IOL) and capsule tension ring (CTR) dislocation were presented. All of our cases experienced progressive vision loss without an episode of strenuous physical activity, trauma, or any other ocular disease. Spontaneous dislocation was observed 2.5 to 8 years after uneventful phacosurgery. Each patient underwent complete IOL and CTR removal combined with anterior chamber IOL implantation. No complications were noticed during follow-up. As a result, capsule tension ring does not prevent late IOL dislocation after uncomplicated phacosurgery in the presence of PEX. Therefore, close follow-up is essential for patients with PEX.

  5. SYNERGISTIC EFFECTS of CYCLIC TENSION and TRANSFORMING GROWTH FACTOR-β1 on the AORTIC VALVE MYOFIBROBLAST

    PubMed Central

    Merryman, W. David; Lukoff, Howard D.; Long, Rebecca A.; Engelmayr, George C.; Hopkins, Richard A.; Sacks, Michael S.

    2007-01-01

    Background Phenotypically, the aortic valve interstitial cell (AVIC) is a dynamic myofibroblast, appearing contractile and activated in times of development, disease, and remodeling. The precise mechanism of phenotypic modulation is unclear, but it is speculated that both biomechanical and biochemical factors are influential. Therefore, we hypothesized that isolated and combined treatments of cyclic tension and TGF-β1 would alter the phenotype and subsequent collagen biosynthesis of AVICs in situ. Methods and Results Porcine aortic valve leaflets received 7 and 14 day treatments of 15% cyclic stretch (Tension), 0.5 ng/ml TGF-β1 (TGF), 15% cyclic stretch and 0.5 ng/ml TGF-β1 (Tension+TGF), or neither mechanical nor cytokine stimuli (Null). Tissues were homogenized and assayed for AVIC phenotype (smooth muscle α-actin (SMA)) and collagen biosynthesis (via heat shock protein 47 (Hsp47) which was further verified with type I collagen C-terminal propeptide (CICP)). At both 7 and 14 days, SMA, Hsp47, and CICP quantities were significantly greater (p<0.001) in the Tension+TGF group compared to all other groups. Additionally, Tension alone appeared to maintain SMA and Hsp47 levels that were measured at day 0, while TGF alone elicited an increase in SMA and Hsp47 compared to day 0 levels. Null treatment revealed diminished proteins at both time points. Conclusions Elevated TGF-β1 levels, in the presence of cyclic mechanical tension, resulted in synergistic increases in the contractile and biosynthetic proteins in AVICs. Since cyclic mechanical stimuli can never be relieved in vivo, the presence of TGF-β1 (possibly from infiltrating macrophages) may result in overly biosynthetic AVICs, leading to altered ECM architecture, compromised valve function, and ultimately degenerative valvular disease. PMID:17868877

  6. Biologically active peptides: prospects for drug development.

    PubMed

    Hughes, J

    1980-08-11

    Biologically active peptides aree typified by their unbiquity of distribution, their high receptor affinity and an almost infinite diversity of structure. For these reasons, considerable effort is now being expended to elucidate the possible role of peptides in brain function. This effort has been stimulated by the discovery of a number of new endogenous peptides, such as the enkephalins, endorphins, vasoactive intestinal peptide and neurotensin. At present, there is no clearly defined role for these peptides, although they may form an important basis for the chemical coding of various brain functions, including pain, mood and memory. At present, the potential for drug development of peptide agonists remains in fairly circumscribed areas such as analgesia, pituitary hormone control, and gastrointestinal motor and secretory control. Peptide antagonists may provide a vast field for future development, although only one area, that of antifertility drugs based on LHRH antagonists, shows any promise of immediate success. Industrial research approaches to new peptide agonists and antagonists mainly rely at present on rational drug design through structural analogies. Other fruitful approaches to be considered are the screening of natural microbial and plant products and the possible application of genetic engineering techniques.

  7. Rhamnolipids elicit the same cytotoxic sensitivity between cancer cell and normal cell by reducing surface tension of culture medium.

    PubMed

    Jiang, Lifang; Shen, Chong; Long, Xuwei; Zhang, Guoliang; Meng, Qin

    2014-12-01

    Biosurfactant rhamnolipids have been claimed to show biological activities of inhibiting the proliferation of cancer cells. In this study, the cytotoxicity of rhamnolipids was examined on four cancer cells (HepG2, Caco-2, Hela, MCF-7 cells) and two normal cells (HK-2 cell, primary hepatocyte). Interestingly, both cancer cells and normal cells exhibited similar sensitivities to the addition of rhamnolipids in culture medium, and the cytotoxicity was largely attenuated by the presence of fetal bovine serum (FBS) in culture medium. In correlation of the mono-/di-rhamnolipid cytotoxicity with the surface tension of culture medium, it was found that rhamnolipids triggered cytotoxicity whenever the surface tension of culture medium decreased below 41 mN/m irrespective of the FBS content in culture medium, cell line, or rhamnolipid congener. Similarly, each chemical surfactant (Tween-80, sodium dodecyl sulfate, and sodium dodecyl benzene sulfonate) could cause cytotoxicity on HepG2 cells whenever its addition made the surface tension under 41 mN/m in culture medium with or without the presence of FBS. It seems that rhamnolipids, like chemical surfactants, exhibited cytotoxicity by reducing the surface tension of culture medium rather than by changing its specific molecular structure, which had no selection on tumor cells. This study could offer helps to correct the misleading biological activity of rhamnolipids and to avoid the possible large wastes of time and expenses on developing the applications in antitumor drugs.

  8. Quantitating intracellular oxygen tension in vivo by phosphorescence lifetime measurement

    PubMed Central

    Hirakawa, Yosuke; Yoshihara, Toshitada; Kamiya, Mako; Mimura, Imari; Fujikura, Daichi; Masuda, Tsuyoshi; Kikuchi, Ryohei; Takahashi, Ippei; Urano, Yasuteru; Tobita, Seiji; Nangaku, Masaomi

    2015-01-01

    Hypoxia appears to have an important role in pathological conditions in many organs such as kidney; however, a method to quantify intracellular oxygen tension in vivo has not been well established. In this study, we established an optical method to quantify oxygen tension in mice kidneys using a cationic lipophilic phosphorescence probe, BTPDM1, which has an intracellular oxygen concentration-sensitive phosphorescence lifetime. Since this probe is distributed inside the tubular cells of the mice kidney, we succeeded in detecting acute renal hypoxic conditions and chronic kidney disease. This technique enabled us to estimate intracellular partial pressures of oxygen in vivo by extrapolating the calibration curve generated from cultured tubular cells. Since intracellular oxygen tension is directly related to cellular hypoxic reactions, such as the activation of hypoxia-inducible factors, our method will shed new light on hypoxia research in vivo. PMID:26644023

  9. Membrane tension and peripheral protein density mediate membrane shape transitions

    NASA Astrophysics Data System (ADS)

    Shi, Zheng; Baumgart, Tobias

    2015-01-01

    Endocytosis is a ubiquitous eukaryotic membrane budding, vesiculation and internalization process fulfilling numerous roles including compensation of membrane area increase after bursts of exocytosis. The mechanism of the coupling between these two processes to enable homeostasis is not well understood. Recently, an ultrafast endocytosis (UFE) pathway was revealed with a speed significantly exceeding classical clathrin-mediated endocytosis (CME). Membrane tension reduction is a potential mechanism by which endocytosis can be rapidly activated at remote sites. Here, we provide experimental evidence for a mechanism whereby membrane tension reduction initiates membrane budding and tubulation mediated by endocytic proteins, such as endophilin A1. We find that shape instabilities occur at well-defined membrane tensions and surface densities of endophilin. From our data, we obtain a membrane shape stability diagram that shows remarkable consistency with a quantitative model. This model applies to all laterally diffusive curvature-coupling proteins and therefore a wide range of endocytic proteins.

  10. STAND: Surface Tension for Aggregation Number Determination.

    PubMed

    Garrido, Pablo F; Brocos, Pilar; Amigo, Alfredo; García-Río, Luis; Gracia-Fadrique, Jesús; Piñeiro, Ángel

    2016-04-26

    Taking advantage of the extremely high dependence of surface tension on the concentration of amphiphilic molecules in aqueous solution, a new model based on the double equilibrium between free and aggregated molecules in the liquid phase and between free molecules in the liquid phase and those adsorbed at the air/liquid interface is presented and validated using literature data and fluorescence measurements. A key point of the model is the use of both the Langmuir isotherm and the Gibbs adsorption equation in terms of free molecules instead of the nominal concentration of the solute. The application of the model should be limited to non ionic compounds since it does not consider the presence of counterions. It requires several coupled nonlinear fittings for which we developed a software that is publicly available in our server as a web application. Using this tool, it is straightforward to get the average aggregation number of an amphiphile, the micellization free energy, the adsorption constant, the maximum surface excess (and so the minimum area per molecule), the distribution of solute in the liquid phase between free and aggregate species, and the surface coverage in only a couple of seconds, just by uploading a text file with surface tension vs concentration data and the corresponding uncertainties.

  11. Update on Normal Tension Glaucoma

    PubMed Central

    Mallick, Jyotiranjan; Devi, Lily; Malik, Pradeep K.; Mallick, Jogamaya

    2016-01-01

    Normal tension glaucoma (NTG) is labelled when typical glaucomatous disc changes, visual field defects and open anterior chamber angles are associated with intraocular pressure (IOP) constantly below 21 mmHg. Chronic low vascular perfusion, Raynaud's phenomenon, migraine, nocturnal systemic hypotension and over-treated systemic hypertension are the main causes of normal tension glaucoma. Goldmann applanation tonometry, gonioscopy, slit lamp biomicroscopy, optical coherence tomography and visual field analysis are the main tools of investigation for the diagnosis of NTG. Management follows the same principles of treatment for other chronic glaucomas: To reduce IOP by a substantial amount, sufficient to prevent disabling visual loss. Treatment is generally aimed to lower IOP by 30% from pre-existing levels to 12-14 mmHg. Betaxolol, brimonidine, prostaglandin analogues, trabeculectomy (in refractory cases), systemic calcium channel blockers (such as nifedipine) and 24-hour monitoring of blood pressure are considered in the management of NTG. The present review summarises risk factors, causes, pathogenesis, diagnosis and management of NTG. PMID:27413503

  12. Entropic Tension in Crowded Membranes

    PubMed Central

    Lindén, Martin; Sens, Pierre; Phillips, Rob

    2012-01-01

    Unlike their model membrane counterparts, biological membranes are richly decorated with a heterogeneous assembly of membrane proteins. These proteins are so tightly packed that their excluded area interactions can alter the free energy landscape controlling the conformational transitions suffered by such proteins. For membrane channels, this effect can alter the critical membrane tension at which they undergo a transition from a closed to an open state, and therefore influence protein function in vivo. Despite their obvious importance, crowding phenomena in membranes are much less well studied than in the cytoplasm. Using statistical mechanics results for hard disk liquids, we show that crowding induces an entropic tension in the membrane, which influences transitions that alter the projected area and circumference of a membrane protein. As a specific case study in this effect, we consider the impact of crowding on the gating properties of bacterial mechanosensitive membrane channels, which are thought to confer osmoprotection when these cells are subjected to osmotic shock. We find that crowding can alter the gating energies by more than in physiological conditions, a substantial fraction of the total gating energies in some cases. Given the ubiquity of membrane crowding, the nonspecific nature of excluded volume interactions, and the fact that the function of many membrane proteins involve significant conformational changes, this specific case study highlights a general aspect in the function of membrane proteins. PMID:22438801

  13. Measurement of dynamic surface tension by mechanically vibrated sessile droplets.

    PubMed

    Iwata, Shuichi; Yamauchi, Satoko; Yoshitake, Yumiko; Nagumo, Ryo; Mori, Hideki; Kajiya, Tadashi

    2016-04-01

    We developed a novel method for measuring the dynamic surface tension of liquids using mechanically vibrated sessile droplets. Under continuous mechanical vibration, the shape of the deformed droplet was fitted by numerical analysis, taking into account the force balance at the drop surface and the momentum equation. The surface tension was determined by optimizing four parameters: the surface tension, the droplet's height, the radius of the droplet-substrate contact area, and the horizontal symmetrical position of the droplet. The accuracy and repeatability of the proposed method were confirmed using drops of distilled water as well as viscous aqueous glycerol solutions. The vibration frequency had no influence on surface tension in the case of pure liquids. However, for water-soluble surfactant solutions, the dynamic surface tension gradually increased with vibration frequency, which was particularly notable for low surfactant concentrations slightly below the critical micelle concentration. This frequency dependence resulted from the competition of two mechanisms at the drop surface: local surface deformation and surfactant transport towards the newly generated surface.

  14. Measurement of dynamic surface tension by mechanically vibrated sessile droplets

    NASA Astrophysics Data System (ADS)

    Iwata, Shuichi; Yamauchi, Satoko; Yoshitake, Yumiko; Nagumo, Ryo; Mori, Hideki; Kajiya, Tadashi

    2016-04-01

    We developed a novel method for measuring the dynamic surface tension of liquids using mechanically vibrated sessile droplets. Under continuous mechanical vibration, the shape of the deformed droplet was fitted by numerical analysis, taking into account the force balance at the drop surface and the momentum equation. The surface tension was determined by optimizing four parameters: the surface tension, the droplet's height, the radius of the droplet-substrate contact area, and the horizontal symmetrical position of the droplet. The accuracy and repeatability of the proposed method were confirmed using drops of distilled water as well as viscous aqueous glycerol solutions. The vibration frequency had no influence on surface tension in the case of pure liquids. However, for water-soluble surfactant solutions, the dynamic surface tension gradually increased with vibration frequency, which was particularly notable for low surfactant concentrations slightly below the critical micelle concentration. This frequency dependence resulted from the competition of two mechanisms at the drop surface: local surface deformation and surfactant transport towards the newly generated surface.

  15. Manufacturing development of low activation vanadium alloys

    SciTech Connect

    Smith, J.P.; Johnson, W.R.; Baxi, C.B.

    1996-10-01

    General Atomics is developing manufacturing methods for vanadium alloys as part of a program to encourage the development of low activation alloys for fusion use. The culmination of the program is the fabrication and installation of a vanadium alloy structure in the DIII-D tokamak as part of the Radiative Divertor modification. Water-cooled vanadium alloy components will comprise a portion of the new upper divertor structure. The first step, procuring the material for this program has been completed. The largest heat of vanadium alloy made to date, 1200 kg of V-4Cr-4Ti, has been produced and is being converted into various product forms. Results of many tests on the material during the manufacturing process are reported. Research into potential fabrication methods has been and continues to be performed along with the assessment of manufacturing processes particularly in the area of joining. Joining of vanadium alloys has been identified as the most critical fabrication issue for their use in the Radiative Divertor Program. Joining processes under evaluation include resistance seam, electrodischarge (stud), friction and electron beam welding. Results of welding tests are reported. Metallography and mechanical tests are used to evaluate the weld samples. The need for a protective atmosphere during different welding processes is also being determined. General Atomics has also designed, manufactured, and will be testing a helium-cooled, high heat flux component to assess the use of helium cooled vanadium alloy components for advanced tokamak systems. The component is made from vanadium alloy tubing, machined to enhance the heat transfer characteristics, and joined to end flanges to allow connection to the helium supply. Results are reported.

  16. Quantitative assessment of tension in wires of fine-wire external fixators.

    PubMed

    Dong, Yin; Saleh, Micheal; Yang, Lang

    2005-01-01

    Fine-wire fixators are widely used in fracture management. Stable fixation requires the wires maintaining tension throughout the treatment. Clinical experience indicates that wire site complications relate to wire tension. However, there lacks a method to assess wire tension quantitatively in the clinic. The objective of this study was to develop a quantitative assessment method for in situ wire tension and to investigate the factors that influence the assessment. An apparatus was developed based on a linear variable differential transformer (LVDT) displacement transducer that measured the deflection of the testing wire with respect to a parallel reference wire when a constant transverse force of 30N was applied to the testing wire. The wire deflection measured was correlated with the wire tension measured by the force transducer. The experiment was performed under different conditions to assess the effect of bone-clamp distance, reference wire tension, number of wires, and fracture stiffness. The results showed that there was a significant and negative correlation between wire tension and deflection and the bone-clamp distance was the most important factor that affected the wire tension-deflection relationship. The assessment method makes it possible to investigate the relationship between wire tension and wire site complications in the clinic.

  17. Surface tension propellant control for Viking 75 Orbiter

    NASA Technical Reports Server (NTRS)

    Dowdy, M. W.; Hise, R. E.; Peterson, R. G.; Debrock, S. C.

    1976-01-01

    The paper describes the selection, development and qualification of the surface tension system and includes results of low-g drop tower tests of scale models, 1-g simulation tests of low-g large ullage settling and liquid withdrawal, structural qualification tests, and propellant surface tension/contact angle studies. Subscale testing and analyses were used to evaluate the ability of the system to maintain or recover the desired propellant orientation following possible disturbances during the Viking mission. This effort included drop tower tests to demonstrate that valid wick paths exist for moving any displaced propellant back over the tank outlet. Variations in surface tension resulting from aging, temperature, and lubricant contamination were studied and the effects of surface finish, referee fluid exposure, aging, and lubricant contamination on contact angle were assessed. Results of movies of typical subscale drop tower tests and full scale slosh tests are discussed.

  18. Second-order wave effects on TLP tendon tension responses

    SciTech Connect

    Xue, H.; Mercier, R.S.

    1996-12-31

    This paper presents a general procedure for analyzing the second-order wave effects on the tendon tension responses of a TLP. The approach solves both first- and second-order equation of motions for a TLP system in frequency domain. Viscous effects are included in the form of statistically linearized damping coefficients. An efficient algorithm has been devised for reducing the burden of second-order wave diffraction analysis, which selects the interacting frequency pairs according to springing frequency of interest to minimize the cost of computing quadratic transfer functions (QTFs) and allow accurate interpolation of QTFs. Moment statistics of the tension process are computed through an eigenvalue analysis. The developed method is applied to analyze the tendon tension responses of a TLP design in water depth of 3,000 ft.

  19. Reefing Line Tension in CPAS Main Parachute Clusters

    NASA Technical Reports Server (NTRS)

    Ray, Eric S.

    2013-01-01

    Reefing lines are an essential feature to manage inflation loads. During each Engineering Development Unit (EDU) test of the Capsule Parachute Assembly System (CPAS), a chase aircraft is staged to be level with the cluster of Main ringsail parachutes during the initial inflation and reefed stages. This allows for capturing high-quality still photographs of the reefed skirt, suspension line, and canopy geometry. The over-inflation angles are synchronized with measured loads data in order to compute the tension force in the reefing line. The traditional reefing tension equation assumes radial symmetry, but cluster effects cause the reefed skirt of each parachute to elongate to a more elliptical shape. This effect was considered in evaluating multiple parachutes to estimate the semi-major and semi-minor axes. Three flight tests are assessed, including one with a skipped first stage, which had peak reefing line tension over three times higher than the nominal parachute disreef sequence.

  20. Computational Tension Mapping of Adherent Cells Based on Actin Imaging.

    PubMed

    Manifacier, Ian; Milan, Jean-Louis; Jeanneau, Charlotte; Chmilewsky, Fanny; Chabrand, Patrick; About, Imad

    2016-01-01

    Forces transiting through the cytoskeleton are known to play a role in adherent cell activity. Up to now few approaches haves been able to determine theses intracellular forces. We thus developed a computational mechanical model based on a reconstruction of the cytoskeleton of an adherent cell from fluorescence staining of the actin network and focal adhesions (FA). Our custom made algorithm converted the 2D image of an actin network into a map of contractile interactions inside a 2D node grid, each node representing a group of pixels. We assumed that actin filaments observed under fluorescence microscopy, appear brighter when thicker, we thus presumed that nodes corresponding to pixels with higher actin density were linked by stiffer interactions. This enabled us to create a system of heterogeneous interactions which represent the spatial organization of the contractile actin network. The contractility of this interaction system was then adapted to match the level of force the cell truly exerted on focal adhesions; forces on focal adhesions were estimated from their vinculin expressed size. This enabled the model to compute consistent mechanical forces transiting throughout the cell. After computation, we applied a graphical approach on the original actin image, which enabled us to calculate tension forces throughout the cell, or in a particular region or even in single stress fibers. It also enabled us to study different scenarios which may indicate the mechanical role of other cytoskeletal components such as microtubules. For instance, our results stated that the ratio between intra and extra cellular compression is inversely proportional to intracellular tension.

  1. Computational Tension Mapping of Adherent Cells Based on Actin Imaging

    PubMed Central

    Manifacier, Ian; Milan, Jean-Louis; Jeanneau, Charlotte; Chmilewsky, Fanny; Chabrand, Patrick; About, Imad

    2016-01-01

    Forces transiting through the cytoskeleton are known to play a role in adherent cell activity. Up to now few approaches haves been able to determine theses intracellular forces. We thus developed a computational mechanical model based on a reconstruction of the cytoskeleton of an adherent cell from fluorescence staining of the actin network and focal adhesions (FA). Our custom made algorithm converted the 2D image of an actin network into a map of contractile interactions inside a 2D node grid, each node representing a group of pixels. We assumed that actin filaments observed under fluorescence microscopy, appear brighter when thicker, we thus presumed that nodes corresponding to pixels with higher actin density were linked by stiffer interactions. This enabled us to create a system of heterogeneous interactions which represent the spatial organization of the contractile actin network. The contractility of this interaction system was then adapted to match the level of force the cell truly exerted on focal adhesions; forces on focal adhesions were estimated from their vinculin expressed size. This enabled the model to compute consistent mechanical forces transiting throughout the cell. After computation, we applied a graphical approach on the original actin image, which enabled us to calculate tension forces throughout the cell, or in a particular region or even in single stress fibers. It also enabled us to study different scenarios which may indicate the mechanical role of other cytoskeletal components such as microtubules. For instance, our results stated that the ratio between intra and extra cellular compression is inversely proportional to intracellular tension. PMID:26812601

  2. Measuring Interfacial Tension Between Immiscible Liquids

    NASA Technical Reports Server (NTRS)

    Rashidnia, Nasser; Balasubramaniam, R.; Delsignore, David M.

    1995-01-01

    Glass capillary tube technique measures interfacial tension between two immiscible liquids. Yields useful data over fairly wide range of interfacial tensions, both for pairs of liquids having equal densities and pairs of liquids having unequal densities. Data on interfacial tensions important in diverse industrial chemical applications, including enhanced extraction of oil; printing; processing foods; and manufacture of paper, emulsions, foams, aerosols, detergents, gel encapsulants, coating materials, fertilizers, pesticides, and cosmetics.

  3. Tension experiments on diaphragm metals

    NASA Technical Reports Server (NTRS)

    Henrickson, H B

    1927-01-01

    Strips of german silver, steel, copper, duralumin, nickel and brass were tested in tension in an apparatus in which the change in deflection with time was measured by means of an interferometer. This change in deflection with time caused by the application and removal of a load is defined as "drift" and "recovery," respectively. It was measured in the time interval from approximately 5 seconds to 5 hours after loading. The data are given in a series of graphs in which the drift and recovery are plotted against time. The proportional drift and recovery in five hours are given for a number of the tests, and in addition are shown graphically for nickel and steel.

  4. A new method for measuring the dynamic surface tension of complex-mixture liquid drops

    SciTech Connect

    Zhang, X.; Harris, M.T.; Basaran, O.A.

    1994-06-29

    A simple and accurate technique has been developed for measuring dynamic surface tension. The new technique is based on growing a drop at the end of a fine capillary into another immiscible fluid and can follow the changes in tension at a freshly formed interface during its entire period of evolution. When the relative importance of the surface tension force is large compared to gravitational and viscous forces, shapes of growing drops are sections of spheres and the difference in pressure between the interior and the exterior of the drop {triangle}p is related to the surface tension {sigma} and the radius of curvature R by the static Young-Laplace formula {triangle}p = 2{sigma}/R. In contrast to related work, the new technique can determine the surface tension of an interface with a surface age of a few to tens of milliseconds by measuring transient drop shapes and pressures in 1/6 to 1 millisecond. The capabilities of the new method are demonstrated by performing tension measurements on liquid systems that do not exhibit dynamic surface tension as well as ones that exhibit significant dynamic tension effects. Tension measurements made with surfactant-laden solutions show that variation of surface tension is nonmonotonic in time. In such systems, the dynamic behavior of surface tension is shown to depend upon both the rate of interfacial dilatation and that of surfactant transport. A maximum in the surface tension is attained when the lowering of the surfactant concentration on the drop interface due to its dilatation is balanced by the addition of fresh surfactant to the interface by convection and diffusion.

  5. Shell tension forces propel Dictyostelium slugs forward

    NASA Astrophysics Data System (ADS)

    Rieu, Jean-Paul; Delanoë-Ayari, Hélène

    2012-12-01

    The Dictyostelium slug is an excellent model system for studying collective movements, as it is comprised of about 105 cells all moving together in the same direction. It still remains unclear how this movement occurs and what the physical mechanisms behind it are. By applying our recently developed 3D traction force microscopy, we propose a simple explanation for slug propulsion. Most of the forces are exerted by the sheath surrounding the slug. This secreted shell is under a rather uniform tension (around 50 mN m-1) and will give rise to a tissue under pressure. Finally, we propose that this pressure will naturally push the slug tip forwards if a gradient of shell mechanical properties takes place in the very anterior part of the raised tip.

  6. Surface tension in human pathophysiology and its application as a medical diagnostic tool

    PubMed Central

    Fathi-Azarbayjani, Anahita; Jouyban, Abolghasem

    2015-01-01

    Introduction: Pathological features of disease appear to be quite different. Despite this diversity, the common feature of various disorders underlies physicochemical and biochemical factors such as surface tension. Human biological fluids comprise various proteins and phospholipids which are capable of adsorption at fluid interfaces and play a vital role in the physiological function of human organs. Surface tension of body fluids correlates directly to the development of pathological states. Methods: In this review, the variety of human diseases mediated by the surface tension changes of biological phenomena and the failure of biological fluids to remain in their native state are discussed. Results: Dynamic surface tension measurements of human biological fluids depend on various parameters such as sex, age and changes during pregnancy or certain disease. It is expected that studies of surface tension behavior of human biological fluids will provide additional information and might become useful in medical practice. Theoretical background on surface tension measurement and surface tension values of reference fluids obtained from healthy and sick patients are depicted. Conclusion: It is well accepted that no single biomarker will be effective in clinical diagnosis. The surface tension measurement combined with routine lab tests may be a novel non-invasive method which can not only facilitate the discovery of diagnostic models for various diseases and its severity, but also be a useful tool for monitoring treatment efficacy. We therefore expect that studies of surface tension behavior of human biological fluids will provide additional useful information in medical practice. PMID:25901295

  7. In vivo simultaneous evaluations of sarcomere imaging and muscle fiber tension.

    PubMed

    Wu, Yi-Ning; Ren, Yupeng; Tsai, Liang-Ching; Gao, Fan; Zhang, Li-Qun

    2016-03-21

    Muscle fiber tension and sarcomere length play critical roles in regulating muscle functions and adaptations under pathological conditions. However, methods are lacking to quantify these two variables simultaneously in vivo. A novel force microscope was developed with the unique capabilities of estimating muscle fiber tension and acquiring sarcomere images simultaneously in vivo. The force microscope consisting of a custom microscopic imaging system and a force sensor was used to quantify in vivo sarcomere length, muscle fiber tension and stress of the tibialis cranialis muscle at plantar-flexed and dorsi-flexed positions from 11 rat hind limbs. Results showed that sarcomere images and fiber tension could be measured together in vivo with significantly higher muscle fiber tension and stress and longer sarcomere length at the plantar-flexed position when compared to their counterparts at the dorsi-flexed position. The fiber tension estimated using the force microscope had close agreement with the direct measurements of the fiber tension. The present force microscope with simultaneous characterizations of fiber tension and sarcomere imaging provides us a useful in vivo tool to investigate the roles of muscle tension in regulating sarcomere and muscle fiber functions under physiological and pathological conditions.

  8. Cryogenic fatigue behavior of plain weave glass/epoxy composite laminates under tension tension cycling

    NASA Astrophysics Data System (ADS)

    Shindo, Yasuhide; Takano, Satoru; Horiguchi, Katsumi; Sato, Takashi

    2006-11-01

    This paper focuses on understanding the tension-tension fatigue behavior of woven glass fiber reinforced polymer laminates at cryogenic temperatures. Tension-tension fatigue tests at frequencies of 4 and 10 Hz with a stress ratio of 0.1 were conducted at room temperature, 77 and 4 K. The fatigue stress versus cycles to failure ( S- N) relationships and fatigue limits for 10 6 cycles were obtained. Fractured specimens tested under fatigue tests were also examined with optical microscope.

  9. Using EMG data to constrain optimization procedure improves finger tendon tension estimations during static fingertip force production.

    PubMed

    Vigouroux, Laurent; Quaine, Franck; Labarre-Vila, Annick; Amarantini, David; Moutet, François

    2007-01-01

    Determining tendon tensions of the finger muscles is crucial for the understanding and the rehabilitation of hand pathologies. Since no direct measurement is possible for a large number of finger muscle tendons, biomechanical modelling presents an alternative solution to indirectly evaluate these forces. However, the main problem is that the number of muscles spanning a joint exceeds the number of degrees of freedom of the joint resulting in mathematical under-determinate problems. In the current study, a method using both numerical optimization and the intra-muscular electromyography (EMG) data was developed to estimate the middle finger tendon tensions during static fingertip force production. The method used a numerical optimization procedure with the muscle stress squared criterion to determine a solution while the EMG data of three extrinsic hand muscles serve to enforce additional inequality constraints. The results were compared with those obtained with a classical numerical optimization and a method based on EMG only. The proposed method provides satisfactory results since the tendon tension estimations respected the mechanical equilibrium of the musculoskeletal system and were concordant with the EMG distribution pattern of the subjects. These results were not observed neither with the classical numerical optimization nor with the EMG-based method. This study demonstrates that including the EMG data of the three extrinsic muscles of the middle finger as inequality constraints in an optimization process can yield relevant tendon tensions with regard to individual muscle activation patterns, particularly concerning the antagonist muscles.

  10. Activities to Develop Your Students' Motor Skills.

    ERIC Educational Resources Information Center

    Eastman, Mary Kay; Safran, Joan S.

    1986-01-01

    Instructions and illustrations support this discussion of learning activities designed to remediate deficiences and build skills in balance and/or motor skills for mildly handicapped students who may not have access to physical therapy or adaptive physical education. Appropriate for both regular and special classes, activities include arm…

  11. Phenylephrine Decreases Vascular Tension in Goat Arteries in Specific Circumstances

    PubMed Central

    Raj, Renu R.

    2016-01-01

    Phenylephrine (PE) causes vasoconstriction through alpha adrenergic receptors. PE-induced vasodilatation has also been reported earlier in pre-constricted vessels. Here we demonstrate in spiral strips of goat arteries that addition of PE can decrease tone even from base-line levels (i.e. not pre-constricted) and show that this process requires nitric oxide (NO) and alpha adrenergic stimulation, but is cGMP-independent. Under control conditions, PE caused vasoconstriction, but under conditions where NO levels are higher, as with L-Arginine or sodium nitroprusside, PE decreased vessel tension. L-Arginine/PE combination was not able to decrease tension when alpha adrenoceptors were blocked with Phentolamine or endothelial nitric oxide synthase (eNOS) was blocked with Nω-Nitro-L-arginine (L-NNA). Propranolol, a beta blocker, was unable to prevent the reduction in tension by the L-Arginine/PE combination. Adrenaline and noradrenaline (and not isoproterenol) also reduced vessel tension in the presence of L-Arginine. Even when NO levels were not enhanced, relieving NO from having to stimulate the enzyme soluble guanylyl cyclase (sGC) (either by using sGC blockers, namely ODQ or methylene blue, or by enhancing cGMP levels (with sildenafil) which by negative feedback probably inhibits sGC) led to PE-induced reduction of vascular tension. PMA—phorbol myristate acetate—an agonist which stimulates Protein Kinase C was able to prevent the ability of PE to reduce vascular tension in a high NO environment. Our conclusion is that PE reduces vascular tension through alpha adrenoceptors if there is excess NO availability to activate a putative pathway. Though the reduction of vessel tone by PE is dependent on NO, it is independent of cGMP. Prior treatment with PMA or PE itself can prevent further PE-induced reduction of tension in a high NO environment. The results here suggest, counter-intuitively, that alpha blockers may be of help in the treatment of septic shock where

  12. Phenylephrine Decreases Vascular Tension in Goat Arteries in Specific Circumstances.

    PubMed

    Raj, Renu R; Subramani, Sathya

    2016-01-01

    Phenylephrine (PE) causes vasoconstriction through alpha adrenergic receptors. PE-induced vasodilatation has also been reported earlier in pre-constricted vessels. Here we demonstrate in spiral strips of goat arteries that addition of PE can decrease tone even from base-line levels (i.e. not pre-constricted) and show that this process requires nitric oxide (NO) and alpha adrenergic stimulation, but is cGMP-independent. Under control conditions, PE caused vasoconstriction, but under conditions where NO levels are higher, as with L-Arginine or sodium nitroprusside, PE decreased vessel tension. L-Arginine/PE combination was not able to decrease tension when alpha adrenoceptors were blocked with Phentolamine or endothelial nitric oxide synthase (eNOS) was blocked with Nω-Nitro-L-arginine (L-NNA). Propranolol, a beta blocker, was unable to prevent the reduction in tension by the L-Arginine/PE combination. Adrenaline and noradrenaline (and not isoproterenol) also reduced vessel tension in the presence of L-Arginine. Even when NO levels were not enhanced, relieving NO from having to stimulate the enzyme soluble guanylyl cyclase (sGC) (either by using sGC blockers, namely ODQ or methylene blue, or by enhancing cGMP levels (with sildenafil) which by negative feedback probably inhibits sGC) led to PE-induced reduction of vascular tension. PMA-phorbol myristate acetate-an agonist which stimulates Protein Kinase C was able to prevent the ability of PE to reduce vascular tension in a high NO environment. Our conclusion is that PE reduces vascular tension through alpha adrenoceptors if there is excess NO availability to activate a putative pathway. Though the reduction of vessel tone by PE is dependent on NO, it is independent of cGMP. Prior treatment with PMA or PE itself can prevent further PE-induced reduction of tension in a high NO environment. The results here suggest, counter-intuitively, that alpha blockers may be of help in the treatment of septic shock where nitric

  13. Effect of Gravity on Surface Tension

    NASA Technical Reports Server (NTRS)

    Weislogel, M. M.; Azzam, M. O. J.; Mann, J. A.

    1998-01-01

    Spectroscopic measurements of liquid-vapor interfaces are made in +/- 1-g environments to note the effect of gravity on surface tension. A slight increase is detected at -1-g0, but is arguably within the uncertainty of the measurement technique. An increased dependence of surface tension on the orientation and magnitude of the gravitational vector is anticipated as the critical point is approached.

  14. Active diffraction gratings: Development and tests

    NASA Astrophysics Data System (ADS)

    Bonora, S.; Frassetto, F.; Zanchetta, E.; Della Giustina, G.; Brusatin, G.; Poletto, L.

    2012-12-01

    We present the realization and characterization of an active spherical diffraction grating with variable radius of curvature to be used in grazing-incidence monochromators. The device consists of a bimorph deformable mirror on the top of which a diffraction grating with laminar profile is realized by UV lithography. The experimental results show that the active grating can optimize the beam focalization of visible wavelengths through its rotation and focus accommodation.

  15. 24 CFR 570.203 - Special economic development activities.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 3 2010-04-01 2010-04-01 false Special economic development... § 570.203 Special economic development activities. A recipient may use CDBG funds for special economic... part of an economic development project. Guidelines for selecting activities to assist under...

  16. 24 CFR 570.203 - Special economic development activities.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 3 2013-04-01 2013-04-01 false Special economic development... § 570.203 Special economic development activities. A recipient may use CDBG funds for special economic... part of an economic development project. Guidelines for selecting activities to assist under...

  17. 24 CFR 570.203 - Special economic development activities.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 3 2012-04-01 2012-04-01 false Special economic development... § 570.203 Special economic development activities. A recipient may use CDBG funds for special economic... part of an economic development project. Guidelines for selecting activities to assist under...

  18. 24 CFR 570.203 - Special economic development activities.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 3 2014-04-01 2013-04-01 true Special economic development... § 570.203 Special economic development activities. A recipient may use CDBG funds for special economic... part of an economic development project. Guidelines for selecting activities to assist under...

  19. Auger tension leg platform cathodic protection system

    SciTech Connect

    Goolsby, A.D.; Smith, J.D.

    1995-11-01

    In 1986, Shell began investigating corrosion control systems for a generic 3,000 ft. water depth Tension Leg Platform (TLP) type structure to be located in the north-central Gulf of Mexico. In 1987, the 2,850 ft. deep Garden Banks block 426 ``Auger`` location was chosen for the first TLP, and the detailed design process began in earnest. During late 1993 and early 1994, the Auger hull was mated with the other components at its permanent site, and first oil and gas production began April 15, 1994. This paper describes the corrosion control design for the exterior submerged and buried steel surfaces of the 2,850 ft. (869 m) water depth Auger Tension Leg Platform structure. Each major type of component (hull, subsea marine wellhead/guidebase, tendon foundation template, tendon, and production riser) has its own combination of coating system and cathodic protection system designed for a thirty five year lifetime. Cathodic protection (CP) is achieved using a variety of sacrificial anode alloys and geometries (e.g. bracelet, flush-mount, and standoff anodes). Anode and cathode CP design parameters for each component depend upon water depth, and were developed using field test data, laboratory studies, field measurements on existing structures, and available literature information. CP design was performed using design spreadsheets constructed for each component, which optimized anode geometries. Extensive quality assurance efforts were part of the anode procurement process, to ensure performance for the intended life of the corrosion-control systems. Results of early in-service CP surveys of the tendons and guidebases are presented, showing the successful achievement of cathodic protection against seawater corrosion. Corrosion control of one additional system, the eight point lateral mooring system, is not addressed here.

  20. Myosin light chain kinase-regulated endothelial cell contraction: the relationship between isometric tension, actin polymerization, and myosin phosphorylation

    PubMed Central

    1995-01-01

    The phosphorylation of regulatory myosin light chains by the Ca2+/calmodulin-dependent enzyme myosin light chain kinase (MLCK) has been shown to be essential and sufficient for initiation of endothelial cell retraction in saponin permeabilized monolayers (Wysolmerski, R. B. and D. Lagunoff. 1990. Proc. Natl. Acad. Sci. USA. 87:16-20). We now report the effects of thrombin stimulation on human umbilical vein endothelial cell (HUVE) actin, myosin II and the functional correlate of the activated actomyosin based contractile system, isometric tension development. Using a newly designed isometric tension apparatus, we recorded quantitative changes in isometric tension from paired monolayers. Thrombin stimulation results in a rapid sustained isometric contraction that increases 2- to 2.5-fold within 5 min and remains elevated for at least 60 min. The phosphorylatable myosin light chains from HUVE were found to exist as two isoforms, differing in their molecular weights and isoelectric points. Resting isometric tension is associated with a basal phosphorylation of 0.54 mol PO4/mol myosin light chain. After thrombin treatment, phosphorylation rapidly increases to 1.61 mol PO4/mol myosin light chain within 60 s and remains elevated for the duration of the experiment. Myosin light chain phosphorylation precedes the development of isometric tension and maximal phosphorylation is maintained during the sustained phase of isometric contraction. Tryptic phosphopeptide maps from both control and thrombin-stimulated cultures resolve both monophosphorylated Ser-19 and diphosphorylated Ser-19/Thr-18 peptides indicative of MLCK activation. Changes in the polymerization of actin and association of myosin II correlate temporally with the phosphorylation of myosin II and development of isometric tension. Activation results in a 57% increase in F-actin content within 90 s and 90% of the soluble myosin II associates with the reorganizing F-actin. Furthermore, the disposition of actin and

  1. Utilizing Student Feedback to Inform Faculty Development Activities for Online Course Development and Delivery

    ERIC Educational Resources Information Center

    Young, Andria; Hoerig, Beverley

    2013-01-01

    The purpose of the present study is to describe faculty development activities at one university and to show how these activities were reviewed for relevance to students. As a means to validate faculty development activities and make adjustments for future development activities, a survey of students was undertaken. A survey was completed by…

  2. Evidence of the late lignification of the G-layer in Simarouba tension wood, to assist understanding how non-G-layer species produce tensile stress.

    PubMed

    Roussel, Jean-Romain; Clair, Bruno

    2015-12-01

    To recover verticality after disturbance, angiosperm trees produce 'tension wood' allowing them to bend actively. The driving force of the tension has been shown to take place in the G-layer, a specific unlignified layer of the cell wall observed in most temperate species. However, in tropical rain forests, the G-layer is often absent and the mechanism generating the forces to reorient trees remains unclear. A study was carried out on tilted seedlings, saplings and adult Simarouba amara Aubl. trees-a species known to not produce a G-layer. Microscopic observations were done on sections of normal and tension wood after staining or observed under UV light to assess the presence/absence of lignin. We showed that S. amara produces a cell-wall layer with all of the characteristics typical of G-layers, but that this G-layer can be observed only as a temporary stage of the cell-wall development because it is masked by a late lignification. Being thin and lignified, tension wood fibres cannot be distinguished from normal wood fibres in the mature wood of adult trees. These observations indicate that the mechanism generating the high tensile stress in tension wood is likely to be the same as that in species with a typical G-layer and also in species where the G-layer cannot be observed in mature cells.

  3. United Nations geothermal activities in developing countries

    SciTech Connect

    Beredjick, N.

    1987-07-01

    The United Nations implements technical cooperation projects in developing countries through its Department of Technical Cooperation for Development (DTCD). The DTCD is mandated to explore for and develop natural resources (water, minerals, and relevant infrastructure) and energy - both conventional and new and renewable energy sources. To date, the United Nations has been involved in over 30 geothermal exploration projects (completed or underway) in 20 developing countries: 8 in Africa (Djibouti, Ethiopia, Kenya, Madagascar); 8 in Asia (China, India, Jordan, Philippines, Thailand); 9 in Latin America (Bolivia, Chile, El Salvador, Honduras, Mexico, Nicaragua, Panama) and 6 in Europe (Greece, Romania, Turkey, Yugoslavia). Today, the DTCD has seven UNDP geothermal projects in 6 developing countries. Four of these (Bolivia, China, Honduras, and Kenya) are major exploration projects whose formulation and execution has been possible thanks to the generous contributions under cost-sharing arrangements from the government of Italy. These four projects are summarized.

  4. Development of Aspherical Active Gratings at NSRRC

    SciTech Connect

    Tseng, T.-C.; Wang, D.-J.; Perng, S.-Y.; Chen, C.-T.; Lin, C.-J.; Kuan, C.-K.; Ho, H.-C.; Wang, J.; Fung, H.S.; Chang, S.-H.

    2007-01-19

    An active grating based on a novel optical concept with bendable polynomial surface profile to reduce the coma and defocus aberrations had been designed and proved by the prototype testing. Due to the low glass transition temperature of the glue and the difference of thermal expansion coefficient between the 17-4 steel bender and silicon, the prototype distorted from flat polished condition when thermally de-blocked the polishing pitch. To improve the thermal deformation of the active grating in the polishing process, a new invar bender and high curing temperature glue were adapted to glue a silicon substrate on the bender. After some tests and manufacturer polishing, it showed acceptable conditions. In this paper we will present the design and preliminary tests of the invar active grating. Meanwhile, the design and analysis of a new 17-4 PH steel bender to be electro-less nickel plating and mechanical ruling for a new beamline will also be discussed.

  5. Tension-dependent nucleosome remodeling at the pericentromere in yeast.

    PubMed

    Verdaasdonk, Jolien S; Gardner, Ryan; Stephens, Andrew D; Yeh, Elaine; Bloom, Kerry

    2012-07-01

    Nucleosome positioning is important for the structural integrity of chromosomes. During metaphase the mitotic spindle exerts physical force on pericentromeric chromatin. The cell must adjust the pericentromeric chromatin to accommodate the changing tension resulting from microtubule dynamics to maintain a stable metaphase spindle. Here we examine the effects of spindle-based tension on nucleosome dynamics by measuring the histone turnover of the chromosome arm and the pericentromere during metaphase in the budding yeast Saccharomyces cerevisiae. We find that both histones H2B and H4 exhibit greater turnover in the pericentromere during metaphase. Loss of spindle-based tension by treatment with the microtubule-depolymerizing drug nocodazole or compromising kinetochore function results in reduced histone turnover in the pericentromere. Pericentromeric histone dynamics are influenced by the chromatin-remodeling activities of STH1/NPS1 and ISW2. Sth1p is the ATPase component of the Remodels the Structure of Chromatin (RSC) complex, and Isw2p is an ATP-dependent DNA translocase member of the Imitation Switch (ISWI) subfamily of chromatin-remodeling factors. The balance between displacement and insertion of pericentromeric histones provides a mechanism to accommodate spindle-based tension while maintaining proper chromatin packaging during mitosis.

  6. Tension regulates myosin dynamics during Drosophila embryonic wound repair.

    PubMed

    Kobb, Anna B; Zulueta-Coarasa, Teresa; Fernandez-Gonzalez, Rodrigo

    2017-02-15

    Embryos repair epithelial wounds rapidly in a process driven by collective cell movements. Upon wounding, actin and the molecular motor non-muscle myosin II are redistributed in the cells adjacent to the wound, forming a supracellular purse string around the lesion. Purse string contraction coordinates cell movements and drives rapid wound closure. By using fluorescence recovery after photobleaching in Drosophila embryos, we found that myosin turns over as the purse string contracts. Myosin turnover at the purse string was slower than in other actomyosin networks that had a lower level of contractility. Mathematical modelling suggested that myosin assembly and disassembly rates were both reduced by tension at the wound edge. We used laser ablation to show that tension at the purse string increased as wound closure progressed, and that the increase in tension was associated with reduced myosin turnover. Reducing purse string tension by laser-mediated severing resulted in increased turnover and loss of myosin. Finally, myosin motor activity was necessary for its stabilization around the wound and for rapid wound closure. Our results indicate that mechanical forces regulate myosin dynamics during embryonic wound repair.

  7. Contractive tension force stack actuator based on soft dielectric EAP

    NASA Astrophysics Data System (ADS)

    Kovacs, Gabor; Düring, Lukas

    2009-03-01

    Among the electronic polymers EAPs especially the dielectric elastomers are functional materials that have promising potential as muscle-like actuators due to their inherent compliancy and good overall performance. The combination of huge active deformations, high energy densities, good efficiencies and fast response is unique to dielectric elastomers. Furthermore, they are lightweight, have a simple structure and can be easily tailored to various applications. Up to now most scientific research work has been focused on the planar expanding actuation mode due to the fact that the commercially available acrylic material VHB 4910 (3M) can easily be processed to planar actuators and has demonstrated very high actuation performance when pre-strained. Many different actuator designs have been developed and tested which expands in plane when voltage is applied and shrinks back as soon as the applied charges are removed from the electrodes. Obviously the contractive operation mode at activation is required for a wide range of application. Due to the principle of operation of soft DE EAP, mainly two directions to performed work against external loads are possible. Beside of the commonly used expanding actuation in planar direction the contractile actuation in thickness direction of the DE film represents a very promising option in the multilayer configuration. First approaches have been presented by the folded actuator design and by the multilayer tactile display device. In this study a novel approach for active structures driven by soft dielectric EAP is presented, which can perform contractive displacements at external tensile load. The device is composed of an array of equal segments, where the dielectric films are arranged in a pile-up configuration. In order to maintain satisfying structural integrity when external tension load is applied special attention was paid to the compliant electrode design which takes a central importance concerning the force transmission

  8. Effect of wire tension on stiffness of tensioned fine wires in external fixation: a mechanical study.

    PubMed

    Antoci, Valentin; Voor, Michael J; Antoci, Valentin; Roberts, Craig S

    2007-09-01

    To determine the effect of changes in magnitude of transfixion wire tension on stiffness of fine-wire external-fixation load deformation, we compared results obtained with different wire tensions (50-140 kg) under identical conditions of central axial compression, medial compression-bending, posterior compression-bending, posteromedial compression-bending, and torsion. Stiffness values were calculated from the load-deformation and torque-angle curves. Tension of 140 kg provided the most stiffness, and there was a trend toward increasing overall stiffness with increasing wire tension. The 1.8-mm wires should be tensioned to at least 110 kg in most cases of fine-wire external fixation; compared with all tensions less than 110 kg, this tension provides significantly more mechanical stability in all loading modes.

  9. [The inversion of concepts about biological role of system rennin-angiotensin II- aldosterone and functions of arterial tension as a metabolism regulator].

    PubMed

    Titov, V N

    2015-02-01

    The phylogenetic theory of general pathology postulates that in physiology and pathology the concepts of biological role of arterial tension had been subjected to inversion. The activation by nephron of synthesis of components rennin-angiotensin II and increasing of aldosterone secretion are directed not to increase arterial tension but to preserve volume of piece of third world ocean privatized by each entity as pool of intercellular medium where all cells continue to live as billions years before. In phylogenetic sense, early organs can't regulate effect of physical factor of regulation of metabolism the late one in phylogenesis of arterial tension. The cause of increasing of arterial tension is the vasomotor center but not the kidneys. The vasomotor center increases arterial tension in the proximal section and further hydrodynamic tension in the distal section of arterial stream and tends to resuscitate function of nephrons, biological function of endoecology and biological reaction of excretion. The arterial tension, besides the main role in biological function of locomotion, is a physical factor of compensation of disorders of biological functions of homeostasis, trophology, endoecology and adaptation. In phylogenesis, three levels of metabolism regulation has been developed The specific regulation of biochemical reactions occurs on autocrine level. In paracrin regulated cell cenosises, at distal section of arterial stream, metabolism is regulated by billions of local peristaltic pumps through compensation of biological reaction of endothelium-depended vasodilatation, micro-circulation, effect of humoral mediators and hormonal principles. In vivo, from the level of vasomotor center, metabolism non-specifically and systemic regulates physical factor-arterial tension through sympathetic activation of heart. The arterial tension in proximal section of arterial stream overcomes resistance and physically "forces through" arterioles with disordered micro

  10. An interlaminar tension strength specimen

    NASA Technical Reports Server (NTRS)

    Jackson, Wade C.; Martin, Roderick H.

    1992-01-01

    This paper describes a technique to determine interlaminar tension strength, sigma(sub 3c) of a fiber reinforced composite material using a curved beam. The specimen was a unidirectional curved beam, bent 90 degrees, with straight arms. Attached to each arm was a hinged loading mechanism which was held by the grips of a tensile testing machine. Geometry effects of the specimen, including the effects of loading arm length, inner radius, thickness, and width, were studied. The data sets fell into two categories: low strength corresponding to a macroscopic flaw related failure and high strength corresponding to a microscopic flaw related failure. From the data available, the loading arm length had no effect on sigma(sub 3c). The inner radius was not expected to have a significant effect on sigma(sub 3c), but this conclusion could not be confirmed because of differences in laminate quality for each curve geometry. The thicker specimens had the lowest value of sigma(sub 3c) because of poor laminate quality. Width was found to affect the value of sigma(sub 3c) only slightly. The wider specimens generally had a slightly lower strength since more material was under high stress, and hence, had a larger probability of containing a significant flaw.

  11. Professional Development: Identifying Effective Instructional Coaching Activities

    ERIC Educational Resources Information Center

    Mannino, Gina

    2014-01-01

    The purpose of this study was to identify the instructional coaching activities most used by instructional coaches in southeast Texas school districts and to test if there was a relationship between the use of instructional coaching and perceived improvement in the instructional practices of teachers and student achievement. The participants for…

  12. Developing Metacognition: A Basis for Active Learning

    ERIC Educational Resources Information Center

    Vos, Henk; de Graaff, E.

    2004-01-01

    The reasons to introduce formats of active learning in engineering (ALE) such as project work, problem-based learning, use of cases, etc. are mostly based on practical experience, and sometimes from applied research on teaching and learning. Such research shows that students learn more and different abilities than in traditional formats of…

  13. Using Hybrid Modeling to Develop Innovative Activities

    ERIC Educational Resources Information Center

    Lichtman, Brenda; Avans, Diana

    2005-01-01

    This article describes a hybrid activities model that physical educators can use with students in grades four and above to create virtually a limitless array of novel games. A brief introduction to the basic theory is followed by descriptions of some hybrid games. Hybrid games are typically the result of merging two traditional sports or other…

  14. Development of active-transport membrane devices

    SciTech Connect

    Laciak, D.V.

    1994-07-01

    This report introduces the concept of Air Products` AT membranes for the separation of NH{sub 3} and CO{sub 2} from process gas streams and presents results from the first year fabrication concept development studies.

  15. Tension generation by threads of contractile proteins

    PubMed Central

    1977-01-01

    Threads of contractile proteins were formed via extrusion and their isometric tensions and isotonic contraction velocities were measured. We obtained reproducible data by using a new and sensitive tensiometer. The force-velocity curves of actomyosin threads were similar to those of muscle, with isometric tensions of the order of 10g/cm2 and maximum contraction velocites of the order of 10(-2) lengths/s. The data could be fitted by Hill's equation. Addition of tropomyosin and troponin to the threads increased isometric tension and maximum contraction velocity. Threads which contained troponin and tropomyosin required Ca++ for contraction and the dependence of their isometric tension on the level of free Ca++ was like that of muscle. The dependence of tension or of contraction velocity upon temperature or upon ionic strength is similar for actomyosin threads and muscle fibers. In contrast, the dependence of most parameters which are characteristic of the actomyosin interaction in solution (or suspension) upon these variables is not similar to the dependence of the muscle fiber parameters. The conclusion we have drawn from these results is that the mechanism of tension generation in the threads is similar to the mechanism that exists in muscle. Because the protein composition of the thread system can be manipulated readily and because the tensions and velocities of the threads can be related directly to the physiological parameters of muscle fibers, the threads provide a powerful method for studying contractile proteins. PMID:137958

  16. Science. Iowa Developed Energy Activity Sampler, 6-12. Revised.

    ERIC Educational Resources Information Center

    Iowa State Dept. of Education, Des Moines. Div. of Instructional Services.

    The revised Iowa Developed Energy Activity Sampler (IDEAS) was compiled using the original IDEAS program and the Energy Conservation Activity Packets (ECAPS). This document is one of a series of revised IDEAS booklets, and provides activities for teaching science. The activities are intended to present energy principles in an interesting manner…

  17. Mathematics. Iowa Developed Energy Activity Sampler, 6-12. Revised.

    ERIC Educational Resources Information Center

    Iowa State Dept. of Education, Des Moines.

    The revised Iowa Developed Energy Activity Sampler (IDEAS) was compiled using the original IDEAS program and the Energy Conservation Activity Packets (ECAPS). This document is one of the series of revised IDEAS booklets, and provides activities for teaching mathematics. The activities are intended to present energy principles in an interesting…

  18. Science. Iowa Developed Energy Activity Sampler, 6-12. Revised.

    ERIC Educational Resources Information Center

    Iowa State Dept. of Education, Des Moines.

    The revised Iowa Developed Energy Activity Sampler (IDEAS) was compiled using the original IDEAS program and the Energy Conservation Activity Packets (ECAPS). This document is one of the series of revised IDEAS booklets, and provides activities for teaching science. The activities are intended to present energy principles in an interesting manner…

  19. Tension induced phase transitions in biomimetic fluid membranes

    NASA Astrophysics Data System (ADS)

    Shapiro, Marc; Vlahovska, Petia

    2012-11-01

    Membranes in eukaryotic cells are mixtures of hundreds of lipid species. The lipid diversity enables membranes to phase separate and form domains, called rafts, which play a critical role in cell functions such as signaling and trafficking. The phase transitions underlying raft formation have been extensively studied as a function of temperature and composition. However, the third dimension of the phase diagram, i.e., the tension (2D pressure), is still unexplored because membrane tension is difficult to control and quantify. To overcome this challenge, we develop two approaches, capillary micromechanics and electrodeformation, in which the tension is regulated by the area dilation accompanying deformation of a vesicle (a closed membrane). The first technique consists of forcing an initially quasi-spherical vesicle through a tapered glass microcapillary, while the second method utilizes uniform electric fields to deform the vesicle into an ellipsoid. Domains are visualized using a fluorescent dye, which preferentially partitions in one of the phases. The experimental results suggest that the miscibility temperature (at which domains form in an initially homogeneous membrane) increases with applied tension. Domain motions and coarsening are also investigated.

  20. Measurement of surface and interfacial tension using pendant drop tensiometry.

    PubMed

    Berry, Joseph D; Neeson, Michael J; Dagastine, Raymond R; Chan, Derek Y C; Tabor, Rico F

    2015-09-15

    Pendant drop tensiometry offers a simple and elegant solution to determining surface and interfacial tension - a central parameter in many colloidal systems including emulsions, foams and wetting phenomena. The technique involves the acquisition of a silhouette of an axisymmetric fluid droplet, and iterative fitting of the Young-Laplace equation that balances gravitational deformation of the drop with the restorative interfacial tension. Since the advent of high-quality digital cameras and desktop computers, this process has been automated with high speed and precision. However, despite its beguiling simplicity, there are complications and limitations that accompany pendant drop tensiometry connected with both Bond number (the balance between interfacial tension and gravitational forces) and drop volume. Here, we discuss the process involved with going from a captured experimental image to a fitted interfacial tension value, highlighting pertinent features and limitations along the way. We introduce a new parameter, the Worthington number, Wo, to characterise the measurement precision. A fully functional, open-source acquisition and fitting software is provided to enable the reader to test and develop the technique further.

  1. Theoretical Studies of the Surface Tension of Liquid Metal System

    NASA Technical Reports Server (NTRS)

    Stroud, D. G.; Shih, W. H.

    1985-01-01

    A major goal of this project is to understand the surface tension and other thermophysical properties of liquid metals and alloys from a fundamental viewpoint. The approach is to calculate these quantities by a first principles technique which combines the statistical-mechanical theory of the liquid state with an electronic pseudopotential theory of electrons in metals. The inhomogeneity of the surface is treated using an ionic-density-functional formalism developed with the support of NASA. Of particular interest are the variation of surface tension with temperature and impurity concentration: such variations strongly influence the types of convection which make take place in a low-gravity environment. Some progress has already been achieved in computing the reduction of surface tension due to the presence of low-surface-tension impurities, and the corresponding surface segregation of such impurities. In the coming year, it is planned to concentrate on the surface properties of materials of particular interest to the MSA program: Si, Ga and GaSn alloys. An additional goal is to gain some theoretical understanding of the high temperature thermophysical properties of liquid metals, particularly high melting point materials which have not been studied extensively from a theoretical viewpoint.

  2. Dropwise Condensation of Low Surface Tension Fluids on Omniphobic Surfaces

    PubMed Central

    Rykaczewski, Konrad; Paxson, Adam T.; Staymates, Matthew; Walker, Marlon L.; Sun, Xiaoda; Anand, Sushant; Srinivasan, Siddarth; McKinley, Gareth H.; Chinn, Jeff; Scott, John Henry J.; Varanasi, Kripa K.

    2014-01-01

    Compared to the significant body of work devoted to surface engineering for promoting dropwise condensation heat transfer of steam, much less attention has been dedicated to fluids with lower interfacial tension. A vast array of low-surface tension fluids such as hydrocarbons, cryogens, and fluorinated refrigerants are used in a number of industrial applications, and the development of passive means for increasing their condensation heat transfer coefficients has potential for significant efficiency enhancements. Here we investigate condensation behavior of a variety of liquids with surface tensions in the range of 12 to 28 mN/m on three types of omniphobic surfaces: smooth oleophobic, re-entrant superomniphobic, and lubricant-impregnated surfaces. We demonstrate that although smooth oleophobic and lubricant-impregnated surfaces can promote dropwise condensation of the majority of these fluids, re-entrant omniphobic surfaces became flooded and reverted to filmwise condensation. We also demonstrate that on the lubricant-impregnated surfaces, the choice of lubricant and underlying surface texture play a crucial role in stabilizing the lubricant and reducing pinning of the condensate. With properly engineered surfaces to promote dropwise condensation of low-surface tension fluids, we demonstrate a four to eight-fold improvement in the heat transfer coefficient. PMID:24595171

  3. Dropwise condensation of low surface tension fluids on omniphobic surfaces.

    PubMed

    Rykaczewski, Konrad; Paxson, Adam T; Staymates, Matthew; Walker, Marlon L; Sun, Xiaoda; Anand, Sushant; Srinivasan, Siddarth; McKinley, Gareth H; Chinn, Jeff; Scott, John Henry J; Varanasi, Kripa K

    2014-03-05

    Compared to the significant body of work devoted to surface engineering for promoting dropwise condensation heat transfer of steam, much less attention has been dedicated to fluids with lower interfacial tension. A vast array of low-surface tension fluids such as hydrocarbons, cryogens, and fluorinated refrigerants are used in a number of industrial applications, and the development of passive means for increasing their condensation heat transfer coefficients has potential for significant efficiency enhancements. Here we investigate condensation behavior of a variety of liquids with surface tensions in the range of 12 to 28 mN/m on three types of omniphobic surfaces: smooth oleophobic, re-entrant superomniphobic, and lubricant-impregnated surfaces. We demonstrate that although smooth oleophobic and lubricant-impregnated surfaces can promote dropwise condensation of the majority of these fluids, re-entrant omniphobic surfaces became flooded and reverted to filmwise condensation. We also demonstrate that on the lubricant-impregnated surfaces, the choice of lubricant and underlying surface texture play a crucial role in stabilizing the lubricant and reducing pinning of the condensate. With properly engineered surfaces to promote dropwise condensation of low-surface tension fluids, we demonstrate a four to eight-fold improvement in the heat transfer coefficient.

  4. Isometric force development, isotonic shortening, and elasticity measurements from Ca(2+)-activated ventricular muscle of the guinea pig

    PubMed Central

    Maughan, DW; Low, ES; Alpert, NR

    1978-01-01

    Isometric tension and isotonic shortening were measured at constant levels of calcium activation of varying magnitude in mechanically disrupted EGTA-treated ventricular bundles from guinea pigs. The results were as follows: (a) The effect of creatine phosphate (CP) on peak tension and rate of shortening saturated at a CP concentration more than 10 mM; below that level tension was increased and shortening velocity decreased. We interpreted this to mean that CP above 10 mM was sufficient to buffer MgATP(2-) intracellularly. (b) The activated bundles exhibited an exponential stress-strain relationship and the series elastic properties did not vary appreciably with degree of activation or creatine phosphate level. (c) At a muscle length 20 percent beyond just taut, peak tension increased with Ca(2+) concentration over the range slightly below 10(-6) to slightly above 10(-4)M. (d) By releasing the muscle length-active tension curves were constructed. Force declined to 20 percent peak tension with a decrease in muscle length (after the recoil) of only 11 percent at 10(-4)M Ca(2+) and 6 percent at 4x10(-6)M Ca(2+). (e) The rate of shortening after a release was greater at lower loads. At identical loads (relative to maximum force at a given Ca(2+) level), velocity at a given time after the release was less at lower Ca(2+) concentrations; at 10 M(-5), velocity was 72 percent of that at 10(-4)M, and at 4x10(-6)M, active shortening was usually delayed and was 40 percent of the velocity at 10(-4) M. Thus, under the conditions of these experiments, both velocity and peak tension depend on the level of Ca(2+) activation over a similar range of Ca(2+) concentration. PMID:149182

  5. Linking Employee Development Activity, Social Exchange and Organizational Citizenship Behavior

    ERIC Educational Resources Information Center

    Pierce, Heather R.; Maurer, Todd J.

    2009-01-01

    The authors examined "perceived beneficiary" of employee development (self, organization) for relationships with employee development activity. Perceived organizational support served as a moderator. The authors conclude that employees may engage in development activities to partly benefit their organization to the extent that a positive exchange…

  6. Past Activeness, Solidarity, and Local Development Efforts.

    ERIC Educational Resources Information Center

    Zekeri, Andrew A.; And Others

    1994-01-01

    Draws upon community field theory and human ecology and uses data from 120 rural Pennsylvania school districts to examine the relative contributions of past community actions, development of solidarity, and ecological variables (socioeconomic status, remoteness, previous industrialization, and percentage of residents commuting to work) to the…

  7. Meristematic Activity during Adventitious Root Primordium Development

    PubMed Central

    Haissig, Bruce E.

    1972-01-01

    Intact brittle willows (Salix fragilis L.) were treated so that developing adventitious root primordia in the stems would be subjected to elevated gibberellic acid or reduced endogenous auxin levels. Observations were made of primordia that were initiated during the experiments and of primordia that were established before the experiments began. The results indicated that as primordia became older and contained more cells, auxin basipetally transported in the stem seemed to be of less importance in determining cell number per primordium. Thus, established primordia depended upon this auxin to a lesser extent than primordia which were being initiated. These observations were explained on the basis of differential contributions during primordium development of cell division in the cambium of the stem and in the primordia themselves. As opposed to the effects of reduced auxin levels, applied gibberellic acid reduced the cell number per primordium most in established primordia. Initiating primordia were least affected by gibberellic acid treatment. Gibberellic acid treatment seemed mainly to reduce intraprimordium cell division, on which continued development of established primordia most depends. Seemingly, at least in brittle willow, applied gibberellic acid blocks the action of auxin in primordium development subsequent to the initiation phase. PMID:16658077

  8. Cultural Change, Human Activity, and Cognitive Development

    ERIC Educational Resources Information Center

    Gauvain, Mary; Munroe, Robert L.

    2012-01-01

    Differential cognitive performance across cultural contexts has been a standard result in comparative research. Here we discuss how societal changes occurring when a small-scale traditional community incorporates elements from industrialized society may contribute to cognitive development, and we illustrate this with an analysis of the cognitive…

  9. 24 CFR 570.203 - Special economic development activities.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 3 2011-04-01 2010-04-01 true Special economic development activities. 570.203 Section 570.203 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR COMMUNITY PLANNING AND DEVELOPMENT, DEPARTMENT...

  10. The surface tension of liquid gallium

    NASA Technical Reports Server (NTRS)

    Hardy, S. C.

    1985-01-01

    The surface tension of liquid gallium has been measured using the sessile drop technique in an Auger spectrometer. The experimental method is described. The surface tension in mJ/sq m is found to decrease linearly with increasing temperature and may be represented as 708-0.66(T-29.8), where T is the temperature in centigrade. This result is of interest because gallium has been suggested as a model fluid for Marangoni flow experiments. In addition, the surface tension is of technological significance in the processing of compound semiconductors involving gallium.

  11. Dynamic surface tension analysis of dodecyl sulfate association complexes.

    PubMed

    Quigley, W W; Nabi, A; Prazen, B J; Lenghor, N; Grudpan, K; Synovec, R E

    2001-09-13

    First, a novel calibration method is used to expand the current understanding of spherical drop growth and elongation that occurs during on-line measurements of surface pressure using the dynamic surface tension detector (DSTD). Using a novel surface tension calibration method, the drop radius is calculated as a function of time from experimental drop pressure data and compared to the theoretical drop radius calculated from volumetric flow rate. From this comparison, the drop volume at which the drop shape starts to deviate ( approximately 4 mul) from a spherical shape is readily observed and deviates more significantly by approximately 6 mul drop volume (5% deviation in the ideal spherical drop radius) for the capillary sensing tip employed in the DSTD. From this assessment of drop shape, an experimental method for precise drop detachment referred to as pneumatic drop detachment is employed at a drop volume of 2 mul (two second drops at 60 mul/min) in order to provide rapid dynamic surface tension measurements via the novel on-line calibration methodology. Second, the DSTD is used to observe and study kinetic information for surface-active molecules and association complexes adsorbing to an air-liquid drop interface. Dynamic surface tension measurements are made for sodium dodecyl sulfate (SDS) in the absence and presence of either tetra butyl ammonium (TBA) or chromium (III). Sensitive, indirect detection of chromium and other multiply charged metals at low concentrations is also investigated. The DSTD is utilized in examining the dynamic nature of SDS: cation association at the air-liquid interface of a growing drop. Either TBA or Cr(III) were found to substantially enhance the surface tension lowering of dodecyl sulfate (DS), but the surface tension lowering is accompanied by a considerable kinetic dependence. Essentially, the surface tension lowering of these DS: cation complexes is found to be a fairly slow process in the context of the two second DSTD

  12. Review of active radiation shielding developments

    NASA Astrophysics Data System (ADS)

    Battiston, Roberto

    The radiation risk due to ionizing particles is a critical issue for long duration manned space missions. The ionization losses in the materials of the spacecraft provide passive shielding effectively stopping low energy particles. However, the estimates of the material required to obtain an acceptable level of radiation result in a prohibitive mass. Active electromagnetic shields, which deflect the charged particles, have been considered as an alternative solution. During the last 10 years the interest in this area has grown. A study of active magnetic shielding based on high-temperature superconductors (HTS) was initiated in an ESA study in 2010, continued in the context of the NASA Innovative Advanced Concepts (NIAC) programs (2011-2014) as well as within a dedicated FP7 EU program, SR2S (2013-2015). The aim of these effort was to provide a realistic evaluation of the possibilities based on current technology levels as well extrapolating to reasonable technology advances expected during the next decade. The different configurations considered were assessed in terms of their technical feasibility and shielding efficiency. We present here a status report of the ongoing work and some preliminary results.

  13. Desulfurization sorbent development activities at METC

    SciTech Connect

    Siriwardane, R.V.

    1995-06-01

    Development of a suitable regenerable sorbent is a major barrier issue in the hot gas cleanup program for integrated gasification combined-cycle (IGCC) systems. This has been a challenging problem during the last 20 years, since many of the sorbents developed in the program could not retain their reactivity and physical integrity during repeated cycles of sulfidation and regeneration reactions. A series of promising sorbents (METC 2-10), which were capable of sustaining their reactivity and physical integrity during repeated sulfidation/ regeneration cycles, have been developed at the Morgantown Energy Technology Center (METC). These sorbents were tested both in low-pressure (260 KPa/23 psig) and high-pressure (520 KPa/60.7 psig) fixed-bed reactors at 538{degrees}C (1000{degrees}F) with simulated coal gas. High-pressure testing was continued for 20 cycles with steam regeneration. A major research goal during the last year was to lower the cost of materials utilized during the sorbent preparation. The METC 9 sorbent was prepared by substituting low-cost materials for some of the materials in METC 6 sorbent. The sulfur capacity of the two sorbents were similar during the 20-cycle testing. METC 2 sorbent was exposed to coal gas in the Modular Gas Cleanup Rig and it was later tested in the high-pressure fixed-bed reactor. The reactivity of the METC 2 sorbent was unaffected by the exposure to the coal gas. Development of these sorbents will be continued for both fluid-bed and moving-bed applications.

  14. Advanced Extravehicular Activity Pressure Garment Requirements Development

    NASA Technical Reports Server (NTRS)

    Ross, Amy

    2014-01-01

    The NASA Johnson Space Center advanced pressure garment technology development team is addressing requirements development for exploration missions. Lessons learned from the Z-2 high fidelity prototype development have reiterated that clear low-level requirements and verification methods reduce risk to the government, improve efficiency in pressure garment design efforts, and enable the government to be a smart buyer. The expectation is to provide requirements at the specification level that are validated so that their impact on pressure garment design is understood. Additionally, the team will provide defined verification protocols for the requirements. However, in reviewing exploration space suit high level requirements there are several gaps in the team's ability to define and verify related lower level requirements. This paper addresses the efforts in requirement areas such as mobility/fit/comfort and environmental protection (dust, radiation, plasma, secondary impacts) to determine the by what method the requirements can be defined and use of those methods for verification. Gaps exist at various stages. In some cases component level work is underway, but no system level effort has begun, in other cases no effort has been initiated to close the gap. Status of ongoing efforts and potential approaches to open gaps are discussed.

  15. Extravehicular Activity Technology Development Status and Forecast

    NASA Technical Reports Server (NTRS)

    Chullen, Cinda; Westheimer, David T.

    2011-01-01

    The goal of NASA s current EVA technology effort is to further develop technologies that will be used to demonstrate a robust EVA system that has application for a variety of future missions including microgravity and surface EVA. Overall the objectives will be to reduce system mass, reduce consumables and maintenance, increase EVA hardware robustness and life, increase crew member efficiency and autonomy, and enable rapid vehicle egress and ingress. Over the past several years, NASA realized a tremendous increase in EVA system development as part of the Exploration Technology Development Program and the Constellation Program. The evident demand for efficient and reliable EVA technologies, particularly regenerable technologies was apparent under these former programs and will continue to be needed as future mission opportunities arise. The technological need for EVA in space has been realized over the last several decades by the Gemini, Apollo, Skylab, Space Shuttle, and the International Space Station (ISS) programs. EVAs were critical to the success of these programs. Now with the ISS extension to 2028 in conjunction with a current forecasted need of at least eight EVAs per year, the EVA hardware life and limited availability of the Extravehicular Mobility Units (EMUs) will eventually become a critical issue. The current EMU has successfully served EVA demands by performing critical operations to assemble the ISS and provide repairs of satellites such as the Hubble Space Telescope. However, as the life of ISS and the vision for future mission opportunities are realized, a new EVA systems capability will be needed and the current architectures and technologies under development offer significant improvements over the current flight systems. In addition to ISS, potential mission applications include EVAs for missions to Near Earth Objects (NEO), Phobos, or future surface missions. Surface missions could include either exploration of the Moon or Mars. Providing an

  16. The Effective Lifetime of ACSR Full Tension Splice Connector Operated at Higher Temperature

    SciTech Connect

    Wang, Jy-An John; Lara-Curzio, Edgar; King Jr, Thomas J; Graziano, Joe; Chan, John; Goodwin, Tip

    2009-01-01

    This paper is to address the issues related to integrity of ACSR full tension splice connectors operated at high temperatures. A protocol of integrating analytical and experimental approaches to evaluate the integrity of a full tension single-stage splice connector (SSC) assembly during service at high operating temperature was developed. Based on the developed protocol the effective lifetime evaluation was demonstrated with ACSR Drake conductor SSC systems. The investigation indicates that thermal cycling temperature and frequency, conductor cable tension loading, and the compressive residual stress field within a SSC system have significant impact on the SSC integrity and the associated effective lifetime.

  17. The Dynamic Surface Tension of Water.

    PubMed

    Hauner, Ines M; Deblais, Antoine; Beattie, James K; Kellay, Hamid; Bonn, Daniel

    2017-03-23

    The surface tension of water is an important parameter for many biological or industrial processes, and roughly a factor of 3 higher than that of nonpolar liquids such as oils, which is usually attributed to hydrogen bonding and dipolar interactions. Here we show by studying the formation of water drops that the surface tension of a freshly created water surface is even higher (∼90 mN m(-1)) than under equilibrium conditions (∼72 mN m(-1)) with a relaxation process occurring on a long time scale (∼1 ms). Dynamic adsorption effects of protons or hydroxides may be at the origin of this dynamic surface tension. However, changing the pH does not significantly change the dynamic surface tension. It also seems unlikely that hydrogen bonding or dipole orientation effects play any role at the relatively long time scale probed in the experiments.

  18. The Dynamic Surface Tension of Water

    PubMed Central

    2017-01-01

    The surface tension of water is an important parameter for many biological or industrial processes, and roughly a factor of 3 higher than that of nonpolar liquids such as oils, which is usually attributed to hydrogen bonding and dipolar interactions. Here we show by studying the formation of water drops that the surface tension of a freshly created water surface is even higher (∼90 mN m–1) than under equilibrium conditions (∼72 mN m–1) with a relaxation process occurring on a long time scale (∼1 ms). Dynamic adsorption effects of protons or hydroxides may be at the origin of this dynamic surface tension. However, changing the pH does not significantly change the dynamic surface tension. It also seems unlikely that hydrogen bonding or dipole orientation effects play any role at the relatively long time scale probed in the experiments.

  19. Transcutaneous Determination of Arterial Oxygen Tension

    ERIC Educational Resources Information Center

    Fenner, A.; And Others

    1975-01-01

    Evaluated were two techniques (the conventional method and the new transcutaneous method) of measuring arterial oxygen tension in 20 severely ill preterm and term infants and in 70 healthy infants. (Author/CL)

  20. Phase Behavior of Lipid Bilayers under Tension

    PubMed Central

    Uline, Mark J.; Schick, M.; Szleifer, Igal

    2012-01-01

    Given the proposed importance of membrane tension in regulating cellular functions, we explore the effects of a finite surface tension on phase equilibrium using a molecular theory that captures the quantitative structure of the phase diagram of the tensionless DPPC/DOPC/Cholesterol lipid bilayer. We find that an increase in the surface tension decreases the temperature of the transition from liquid to gel in a pure DPPC system by ∼1.0 K/(mN/m), and decreases the liquid-disordered to liquid-ordered transition at constant chemical potentials by approximately the same amount. Our results quantitatively isolate the role of tension in comparison to other thermodynamic factors, such as pressure, in determining the phase behavior of lipid bilayers. PMID:22325274

  1. Oxygen tension level and human viral infections.

    PubMed

    Morinet, Frédéric; Casetti, Luana; François, Jean-Hugues; Capron, Claude; Pillet, Sylvie

    2013-09-01

    The role of oxygen tension level is a well-known phenomenon that has been studied in oncology and radiotherapy since about 60 years. Oxygen tension may inhibit or stimulate propagation of viruses in vitro as well as in vivo. In turn modulating oxygen metabolism may constitute a novel approach to treat viral infections as an adjuvant therapy. The major transcription factor which regulates oxygen tension level is hypoxia-inducible factor-1 alpha (HIF-1α). Down-regulating the expression of HIF-1α is a possible method in the treatment of chronic viral infection such as human immunodeficiency virus infection, chronic hepatitis B and C viral infections and Kaposi sarcoma in addition to classic chemotherapy. The aim of this review is to supply an updating concerning the influence of oxygen tension level in human viral infections and to evoke possible new therapeutic strategies regarding this environmental condition.

  2. Tension in the LHC diffractive data?

    SciTech Connect

    Gotsman, Errol

    2015-04-10

    I discuss the LHC diffractive data, and compare it to predicted energy behaviour of various models. I suggest that the so called 'tension' between the experimental results, maybe due to the different Monte Carlo programs used.

  3. Active microrheology of fluids inside developing zebrafish

    NASA Astrophysics Data System (ADS)

    Taormina, Mike; Parthasarathy, Raghuveer

    2014-03-01

    Biological fluids are a source of diverse and interesting behavior for the soft matter physicist. Since their mechanical properties must be tuned to fulfill functional roles important to the development and health of living things, they often display complex behavior on length and time scales spanning many orders of magnitude. For microbes colonizing an animal host, for example, the mechanical properties of the host environment are of great importance, affecting mobility and hence the ability to establish a stable population. Indeed, some species possess the ability to affect the fluidity of their environment, both directly by chemically modifying it, and indirectly by influencing the host cells' secretion of mucus. Driving magnetically doped micron-scale probes which have been orally micro-gavaged into the intestinal bulb of a larval zebrafish allows the rheology of the mucosal layer within the fish to be measured over three decades of frequency, complementing ecological data on microbial colonization with physical information about the gut environment. Here, we describe the technique, provide the first measurement of mucosal viscosity in a developing animal, and explore the technique's applicability to other small-volume or spatially inhomogeneous fluid samples.

  4. Relationship between tissue tension and thermal diffusion to peripheral tissue using an energy device.

    PubMed

    Kondo, Akihiro; Nishizawa, Yuji; Ito, Masaaki; Saito, Norio; Fujii, Satoshi; Akamoto, Shintaro; Fujiwara, Masao; Okano, Keiichi; Suzuki, Yasuyuki

    2016-08-01

    The aim of the study was to assess the relationship between tissue tension and thermal diffusion to peripheral tissues using an electric scalpel, ultrasonically activated device, or a bipolar sealing system. The mesentery of pigs was excised with each energy device (ED) at three tissue tensions (0, 300, 600 g). The excision time and thermal diffusion area were monitored with thermography, measured for each ED, and then histologically examined. Correlations between tissue tension and thermal diffusion area were examined. The excision time was inversely correlated with tissue tension for all ED (electric scalpel, r = 0.718; ultrasonically activated device, r = 0.949; bipolar sealing system, r = 0.843), and tissue tension was inversely correlated with the thermal diffusion area with the electric scalpel (r = 0.718) and bipolar sealing system (r = 0.869). Histopathologically, limited deep thermal denaturation occurred at a tension of 600 g with all ED. We conclude that thermal damage can be avoided with adequate tissue tension when any ED is used.

  5. Lignification in poplar tension wood lignified cell wall layers.

    PubMed

    Yoshinaga, Arata; Kusumoto, Hiroshi; Laurans, Françoise; Pilate, Gilles; Takabe, Keiji

    2012-09-01

    The lignification process in poplar tension wood lignified cell wall layers, specifically the S(1) and S(2) layers and the compound middle lamella (CML), was analysed using ultraviolet (UV) and transmission electron microscopy (TEM). Variations in the thickness of the gelatinous layer (G-layer) were also measured to clarify whether the lignified cell wall layers had completed their lignification before the deposition of G-layers, or, on the contrary, if lignification of these layers was still active during G-layer formation. Observations using UV microscopy and TEM indicated that both UV absorbance and the degree of potassium permanganate staining increased in the CML and S(1) and S(2) layers during G-layer formation, suggesting that the lignification of these lignified layers is still in progress during G-layer formation. In the context of the cell-autonomous monolignol synthesis hypothesis, our observations suggest that monolignols must go through the developing G-layer during the lignification of CML and the S(1) and S(2) layers. The alternative hypothesis of external synthesis (in the rays) does not require that monolignols go through the G-layer before being deposited in the CML, or the S(1) and S(2) layers. Interestingly, the previous observation of lignin in the poplar G-layer was not confirmed with the microscopy techniques used in the present study.

  6. Spontaneous oscillation of tension and sarcomere length in skeletal myofibrils. Microscopic measurement and analysis.

    PubMed Central

    Anazawa, T; Yasuda, K; Ishiwata, S

    1992-01-01

    We have devised a simple method for measuring tension development of single myofibrils by micromanipulation with a pair of glass micro-needles. The tension was estimated from the deflection of a flexible needle under an inverted phase-contrast microscope equipped with an image processor, so that the tension development is always accompanied by the shortening of the myofibril (auxotonic condition) in the present setup. The advantage of this method is that the measurement of tension (1/30 s for time resolution and about 0.05 micrograms for accuracy of tension measurement; 0.05 microns as a spatial resolution for displacement of the micro-needle) and the observation of sarcomere structure are possible at the same time, and the technique to hold myofibrils, even single myofibrils, is very simple. This method has been applied to study the tension development of glycerinated skeletal myofibrils under the condition where spontaneous oscillation of sarcomeres is induced, i.e., the coexistence of MgATP, MgADP and inorganic phosphate without free Ca2+. Under this condition, we found that the tension of myofibrils spontaneously oscillates accompanied by the oscillation of sarcomere length with a main period of a few seconds; the period was lengthened and shortened with stretch and release of myofibrils. A possible mechanism of the oscillation is discussed. Images FIGURE 4 PMID:1600075

  7. Low Oxygen Tension Enhances Hepatitis C Virus Replication

    PubMed Central

    Kalliampakou, K. I.; Kotta-Loizou, I.; Befani, C.; Liakos, P.; Simos, G.; Mentis, A. F.; Kalliaropoulos, A.; Doumba, P. P.; Smirlis, D.; Foka, P.; Bauhofer, O.; Poenisch, M.; Windisch, M. P.; Lee, M. E.; Koskinas, J.; Bartenschlager, R.

    2013-01-01

    Low oxygen tension exerts a significant effect on the replication of several DNA and RNA viruses in cultured cells. In vitro propagation of hepatitis C virus (HCV) has thus far been studied under atmospheric oxygen levels despite the fact that the liver tissue microenvironment is hypoxic. In this study, we investigated the efficiency of HCV production in actively dividing or differentiating human hepatoma cells cultured under low or atmospheric oxygen tensions. By using both HCV replicons and infection-based assays, low oxygen was found to enhance HCV RNA replication whereas virus entry and RNA translation were not affected. Hypoxia signaling pathway-focused DNA microarray and real-time quantitative reverse transcription-PCR (qRT-PCR) analyses revealed an upregulation of genes related to hypoxic stress, glycolytic metabolism, cell growth, and proliferation when cells were kept under low (3% [vol/vol]) oxygen tension, likely reflecting cell adaptation to anaerobic conditions. Interestingly, hypoxia-mediated enhancement of HCV replication correlated directly with the increase in anaerobic glycolysis and creatine kinase B (CKB) activity that leads to elevated ATP production. Surprisingly, activation of hypoxia-inducible factor alpha (HIF-α) was not involved in the elevation of HCV replication. Instead, a number of oncogenes known to be associated with glycolysis were upregulated and evidence that these oncogenes contribute to hypoxia-mediated enhancement of HCV replication was obtained. Finally, in liver biopsy specimens of HCV-infected patients, the levels of hypoxia and anaerobic metabolism markers correlated with HCV RNA levels. These results provide new insights into the impact of oxygen tension on the intricate HCV-host cell interaction. PMID:23269812

  8. Development of Spontaneous Activity in the Avian Hindbrain

    PubMed Central

    Momose-Sato, Yoko; Sato, Katsushige

    2016-01-01

    Spontaneous activity in the developing central nervous system occurs before the brain responds to external sensory inputs, and appears in the hindbrain and spinal cord as rhythmic electrical discharges of cranial and spinal nerves. This spontaneous activity recruits a large population of neurons and propagates like a wave over a wide region of the central nervous system. Here, we review spontaneous activity in the chick hindbrain by focusing on this large-scale synchronized activity. Asynchronous activity that is expressed earlier than the above mentioned synchronized activity and activity originating in midline serotonergic neurons are also briefly mentioned. PMID:27570506

  9. Oxygen tension level and human viral infections

    SciTech Connect

    Morinet, Frédéric; Casetti, Luana; François, Jean-Hugues; Capron, Claude; Pillet, Sylvie

    2013-09-15

    The role of oxygen tension level is a well-known phenomenon that has been studied in oncology and radiotherapy since about 60 years. Oxygen tension may inhibit or stimulate propagation of viruses in vitro as well as in vivo. In turn modulating oxygen metabolism may constitute a novel approach to treat viral infections as an adjuvant therapy. The major transcription factor which regulates oxygen tension level is hypoxia-inducible factor-1 alpha (HIF-1α). Down-regulating the expression of HIF-1α is a possible method in the treatment of chronic viral infection such as human immunodeficiency virus infection, chronic hepatitis B and C viral infections and Kaposi sarcoma in addition to classic chemotherapy. The aim of this review is to supply an updating concerning the influence of oxygen tension level in human viral infections and to evoke possible new therapeutic strategies regarding this environmental condition. - Highlights: • Oxygen tension level regulates viral replication in vitro and possibly in vivo. • Hypoxia-inducible factor 1 (HIF-1α) is the principal factor involved in Oxygen tension level. • HIF-1α upregulates gene expression for example of HIV, JC and Kaposi sarcoma viruses. • In addition to classical chemotherapy inhibition of HIF-1α may constitute a new track to treat human viral infections.

  10. Ethnography in community psychology: promises and tensions.

    PubMed

    Case, Andrew D; Todd, Nathan R; Kral, Michael J

    2014-09-01

    Community psychology recognizes the need for research methods that illuminate context, culture, diversity, and process. One such method, ethnography, has crossed into multiple disciplines from anthropology, and indeed, community psychologists are becoming community ethnographers. Ethnographic work stands at the intersection of bridging universal questions with the particularities of people and groups bounded in time, geographic location, and social location. Ethnography is thus historical and deeply contextual, enabling a rich, in-depth understanding of communities that is aligned with the values and goals of community psychology. The purpose of this paper is to elucidate the potential of ethnography for community psychology and to encourage its use within the field as a method to capture culture and context, to document process, and to reveal how social change and action occur within and through communities. We discuss the method of ethnography, draw connections to community psychology values and goals, and identify tensions from our experiences doing ethnography. Overall, we assert that ethnography is a method that resonates with community psychology and present this paper as a resource for those interested in using this method in their research or community activism.

  11. A Summary of Design Formulas for Beams Having Thin Webs in Diagonal Tension

    NASA Technical Reports Server (NTRS)

    Kuhn, Paul

    1933-01-01

    This report presents an explanation of the fundamental principles and a summary of the essential formulas for the design of diagonal-tension field beams, i.e. beams with very thin webs, as developed by Professor Wagner of Germany.

  12. Ukrainian Teacher Candidates Develop Dispositions of Socially Meaningful Activity

    ERIC Educational Resources Information Center

    Koshmanova, Tetyana; Ravchyna, Tetyana

    2010-01-01

    This study addresses how the method of peer mediation can be utilized by teacher educators in developing students' attitudes to care for those who are in need, how to actively participate in socially meaningful activity without any expectation of reward, and how to contribute to the democratic development of a post-conflict country via active…

  13. Planning and Development of Lab Training Activities for Powerline Communications

    ERIC Educational Resources Information Center

    Drosopoulos, A.; Hatziprokopiou, M.

    2010-01-01

    This paper discusses the planning and development of student training and activities for the Powerline Communications Laboratory at the Technical Education Institute (TEI), Patras, Greece. Powerline communications is currently an active area of research and development that combines three separate specializations from the standard training of…

  14. The Relation between Employee Organizational and Professional Development Activities

    ERIC Educational Resources Information Center

    Blau, Gary; Andersson, Lynne; Davis, Kathleen; Daymont, Tom; Hochner, Arthur; Koziara, Karen; Portwood, Jim; Holladay, Blair

    2008-01-01

    A model is presented showing hypothesized common and parallel antecedents of employee organizational development activity (ODA) versus professional development activity (PDA). A common antecedent is expected to affect both ODA and PDA, while a parallel antecedent is expected to affect its corresponding work referent. This model was tested using a…

  15. Developing Science and Math Integrated Activities for Middle School Students

    ERIC Educational Resources Information Center

    Sherrod, Sonya Ellouise; Dwyer, Jerry; Narayan, Ratna

    2009-01-01

    This article reports the development and refinement of science and mathematics integrated activities for middle school students. The expectations of the National Council of Teachers of Mathematics that students develop an understanding of mathematics and an ability to apply it gave birth to these activities. The expectations of the National…

  16. Mathematics. Iowa Developed Energy Activity Sampler, 6-12. Revised.

    ERIC Educational Resources Information Center

    Iowa State Dept. of Education, Des Moines. Div. of Instructional Services.

    The revised Iowa Developed Energy Activity Sampler (IDEAS) was compiled using the original IDEAS program and the Energy Conservation Activity Packets (ECAPS). This document contains teaching activities which are intended to strengthen students' mathematics skills and concepts, while broadening their understanding of energy concepts. Each of the 24…

  17. Revisiting Tension Band Fixation for Difficult Patellar Fractures.

    PubMed

    Hambright, Dustin S; Walley, Kempland C; Hall, Amber; Appleton, Paul T; Rodriguez, Edward K

    2017-02-01

    Patella fractures with comminution, osteoporotic bone, and/or previously failed fixation are exceedingly difficult to reduce and fix. Moreover, the risk of symptomatic constructs and patients who are poorly compliant with postoperative activity restrictions can make these complex fracture patterns an even more challenging scenario. Although there is an array of techniques described for comminuted patella fractures, there lacks an accepted surgical technique for these difficult cases. In this clinical series, we describe an enhancement to the traditional tension band construct that uses additional wires and multiple tension bands to gather and fix comminuted fracture patterns in nontransverse planes, bolster osteoporotic bone, and secure fractures in patients undergoing a revision and/or have potential to be poorly compliant with postoperative activity restrictions. The clinical outcomes of 27 patients demonstrate high rates of bony union, functional range of motion, and low rates of both infection and failure. In conclusion, using the basic principles of tension band wiring remains highly versatile, useful, and economical in approaching difficult patella fractures.

  18. Deoxygenation Reduces Sickle Cell Blood Flow at Arterial Oxygen Tension.

    PubMed

    Lu, Xinran; Wood, David K; Higgins, John M

    2016-06-21

    The majority of morbidity and mortality in sickle cell disease is caused by vaso-occlusion: circulatory obstruction leading to tissue ischemia and infarction. The consequences of vaso-occlusion are seen clinically throughout the vascular tree, from the relatively high-oxygen and high-velocity cerebral arteries to the relatively low-oxygen and low-velocity postcapillary venules. Prevailing models of vaso-occlusion propose mechanisms that are relevant only to regions of low oxygen and low velocity, leaving a wide gap in our understanding of the most important pathologic process in sickle cell disease. Progress toward understanding vaso-occlusion is further challenged by the complexity of the multiple processes thought to be involved, including, but not limited to 1) deoxygenation-dependent hemoglobin polymerization leading to impaired rheology, 2) endothelial and leukocyte activation, and 3) altered cellular adhesion. Here, we chose to focus exclusively on deoxygenation-dependent rheologic processes in an effort to quantify their contribution independent of the other processes that are likely involved in vivo. We take advantage of an experimental system that, to our knowledge, uniquely enables the study of pressure-driven blood flow in physiologic-sized tubes at physiologic hematocrit under controlled oxygenation conditions, while excluding the effects of endothelium, leukocyte activation, adhesion, inflammation, and coagulation. We find that deoxygenation-dependent rheologic processes are sufficient to increase apparent viscosity significantly, slowing blood flow velocity at arterial oxygen tension even without additional contributions from inflammation, adhesion, and endothelial and leukocyte activation. We quantify the changes in apparent viscosity and define a set of functional regimes of sickle cell blood flow personalized for each patient that may be important in further dissecting mechanisms of in vivo vaso-occlusion as well as in assessing risk of patient

  19. Development of Microorganisms with Improved Transport and Biosurfactant Activity for Enhanced Oil Recovery

    SciTech Connect

    M.J. McInerney; K.E. Duncan; N. Youssef; T. Fincher; S.K. Maudgalya; M.J. Folmsbee; R. Knapp; Randy R. Simpson; N.Ravi; D. Nagle

    2005-08-15

    The project had three objectives: (1) to develop microbial strains with improved biosurfactant properties that use cost-effective nutrients, (2) to obtain biosurfactant strains with improved transport properties through sandstones, and (3) to determine the empirical relationship between surfactant concentration and interfacial tension and whether in situ reactions kinetics and biosurfactant concentration meets appropriate engineering design criteria. Here, we show that a lipopeptide biosurfactant produced by Bacillus mojavensis strain JF-2 mobilized substantial amounts of residual hydrocarbon from sand-packed columns and Berea sandstone cores when a viscosifying agent and a low molecular weight alcohol were present. The amount of residual hydrocarbon mobilized depended on the biosurfactant concentration. Tertiary oil recovery experiments showed that 10 to 40 mg/l of JF-2 biosurfactant in the presence of 0.1 mM 2,3-butanediol and 1 g/l of partially hydrolyzed polyacrylamide (PHPA) recovered 10-40% of residual oil from Berea sandstone cores. Even low biosurfactant concentrations (16 mg/l) mobilized substantial amounts of residual hydrocarbon (29%). The bio-surfactant lowered IFT by nearly 2 orders of magnitude compared to typical IFT values of 28-29 mN/m. Increasing the salinity increased the IFT with or without 2,3-butanediol present. The lowest interfacial tension observed was 0.1 mN/m. A mathematical model that relates oil recovery to biosurfactant concentration was modified to include the stepwise changes in IFT as biosurfactant concentrations changes. This model adequately predicted the experimentally observed changes in IFT as a function of biosurfactant concentration. Theses data show that lipopeptide biosurfactant systems may be effective in removing hydrocarbon contamination sources in soils and aquifers and for the recovery of entrapped oil from low production oil reservoirs. Diverse microorganisms were screened for biosurfactant production and anaerobic

  20. Lighting Up the Force: Investigating Mechanisms of Mechanotransduction Using Fluorescent Tension Probes

    PubMed Central

    Jurchenko, Carol

    2015-01-01

    The ability of cells to sense the physical nature of their surroundings is critical to the survival of multicellular organisms. Cellular response to physical cues from adjacent cells and the extracellular matrix leads to a dynamic cycle in which cells respond by remodeling their local microenvironment, fine-tuning cell stiffness, polarity, and shape. Mechanical regulation is important in cellular development, normal morphogenesis, and wound healing. The mechanisms by which these finely balanced mechanotransduction events occur, however, are not well understood. In large part, this is due to the limited availability of tools to study molecular mechanotransduction events in live cells. Several classes of molecular tension probes have been recently developed which are rapidly transforming the study of mechanotransduction. Molecular tension probes are primarily based on fluorescence resonance energy transfer (FRET) and report on piconewton scale tension events in live cells. In this minireview, we describe the two main classes of tension probes, genetically encoded tension sensors and immobilized tension sensors, and discuss the advantages and limitations of each type. We discuss future opportunities to address major biological questions and outline the challenges facing the next generation of molecular tension probes. PMID:26031334

  1. Ice Accretion with Varying Surface Tension

    NASA Technical Reports Server (NTRS)

    Bilanin, Alan J.; Anderson, David N.

    1995-01-01

    During an icing encounter of an aircraft in flight, super-cooled water droplets impinging on an airfoil may splash before freezing. This paper reports tests performed to determine if this effect is significant and uses the results to develop an improved scaling method for use in icing test facilities. Simple laboratory tests showed that drops splash on impact at the Reynolds and Weber numbers typical of icing encounters. Further confirmation of droplet splash came from icing tests performed in the NaSA Lewis Icing Research Tunnel (IRT) with a surfactant added to the spray water to reduce the surface tension. The resulting ice shapes were significantly different from those formed when no surfactant was added to the water. These results suggested that the droplet Weber number must be kept constant to properly scale icing test conditions. Finally, the paper presents a Weber-number-based scaling method and reports results from scaling tests in the IRT in which model size was reduced up to a factor of 3. Scale and reference ice shapes are shown which confirm the effectiveness of this new scaling method.

  2. Tension-independent heat in rabbit papillary muscle.

    PubMed Central

    Alpert, N R; Blanchard, E M; Mulieri, L A

    1989-01-01

    1. Heat and force were measured from isometrically contracting (0.2 Hz) rabbit papillary muscles at 21 degrees C during a single contraction-relaxation cycle using antimony-bismuth thermopiles and a capacitance force transducer. 2. Tension-independent heat (TIH) associated with excitation-contraction coupling was isolated from the initial heat by eliminating tension and tension-dependent heat with a Krebs-Ringer solution containing 2,3-butanedione monoxime (BDM) and mannitol. 3. A strategy for testing the validity of this new method for measuring TIH in heart muscle is described and the test confirms that the BDM-hypertonic solution partitioning method properly estimates the magnitude of the TIH component of initial heat. 4. TIH at the time of complete mechanical relaxation is 1.00 +/- 0.17 mJ/g wet weight and the data suggest that calcium cycling is complete by this time. Conversion of TIH to calcium cycled, assuming that 87% of TIH is due to calcium pumping by the sarcoplasmic reticulum, indicates that approximately 52 nmol calcium/g wet weight are required to support a single cycle of mechanical activity (0.2 Hz, 21 degrees C). 5. The length and frequency dependence of excitation-contraction coupling were demonstrated. TIH is reduced by shortening muscle length and by increasing the interval between stimuli. These steady-state data suggest that only a portion (approximately 40%) of TIH is directly related to activation of the contractile apparatus. 6. TIH in the first twitch following a 45 min rest period is significantly reduced by approximately 30%. 7. With subsequent twitches in the positive treppe following the rest period, TIH does not increase as steeply as expected suggesting that tension rise in twitches 1-10 may be modulated by competitive binding of calcium rather than increased calcium delivery. PMID:2607437

  3. Tension-independent heat in rabbit papillary muscle.

    PubMed

    Alpert, N R; Blanchard, E M; Mulieri, L A

    1989-07-01

    1. Heat and force were measured from isometrically contracting (0.2 Hz) rabbit papillary muscles at 21 degrees C during a single contraction-relaxation cycle using antimony-bismuth thermopiles and a capacitance force transducer. 2. Tension-independent heat (TIH) associated with excitation-contraction coupling was isolated from the initial heat by eliminating tension and tension-dependent heat with a Krebs-Ringer solution containing 2,3-butanedione monoxime (BDM) and mannitol. 3. A strategy for testing the validity of this new method for measuring TIH in heart muscle is described and the test confirms that the BDM-hypertonic solution partitioning method properly estimates the magnitude of the TIH component of initial heat. 4. TIH at the time of complete mechanical relaxation is 1.00 +/- 0.17 mJ/g wet weight and the data suggest that calcium cycling is complete by this time. Conversion of TIH to calcium cycled, assuming that 87% of TIH is due to calcium pumping by the sarcoplasmic reticulum, indicates that approximately 52 nmol calcium/g wet weight are required to support a single cycle of mechanical activity (0.2 Hz, 21 degrees C). 5. The length and frequency dependence of excitation-contraction coupling were demonstrated. TIH is reduced by shortening muscle length and by increasing the interval between stimuli. These steady-state data suggest that only a portion (approximately 40%) of TIH is directly related to activation of the contractile apparatus. 6. TIH in the first twitch following a 45 min rest period is significantly reduced by approximately 30%. 7. With subsequent twitches in the positive treppe following the rest period, TIH does not increase as steeply as expected suggesting that tension rise in twitches 1-10 may be modulated by competitive binding of calcium rather than increased calcium delivery.

  4. On the Dialectic Nature of Human Mind: The Dynamic Tension Between Sameness and non-Sameness.

    PubMed

    Komatsu, Koji

    2016-03-01

    Although our environments and ourselves are usually thought about as relatively stable over time, there is always a tension between sameness and non-sameness in our lives. Because any development is considered as emerging non-sameness, I report that the inquiry into the development of human mind must regard this tension as essential. In this paper, first I show that this tension is a highly relational and dynamic phenomenon that cannot be fixed or measured in numerical terms. Non-sameness is not only a result of development but also a ground that leads to further development in the future. After illustrating the function and regulation of the {same <> non-same} tension in development by analyzing an excerpt from a mother-child conversation, I explain that this tension, or more generally the dialectic nature, is within the core of psychological phenomena, in terms that were introduced to psychology by James Mark Baldwin a century ago. These discussions imply the importance of inquiring into the process of development that emerges from the dialectic tension and fluctuations of our movements and that is observable in various relationships, including the relationship between researchers and study participants.

  5. Oxygen tension affects lubricin expression in chondrocytes.

    PubMed

    Hatta, Taku; Kishimoto, Koshi N; Okuno, Hiroshi; Itoi, Eiji

    2014-10-01

    We assessed the effects of oxygen tension on lubricin expression in bovine chondrocytes and cartilage explants and a role for hypoxia-inducible transcription factor (HIF)-1α in regulating lubricin expression was investigated using a murine chondroprogenitor cell line, ATDC5, and bovine chondrocytes isolated from superficial and middle/deep zones of femoral cartilage. ATDC5 cells and bovine chondrocytes were cultured in micromass under different oxygen tensions (21%, 5%, and 1%). ATDC5 cells and middle/deep zone chondrocytes that initially had low lubricin expression levels were also cultured with or without transforming growth factor (TGF)-β1. Quantitative reverse transcription (RT)-PCR was used to determine lubricin and chondrogenic marker gene mRNA levels and immunohistochemistry was used to assess lubricin protein expression. Explant cartilage plugs cultured under different oxygen tensions were also subjected to immunohistological analysis for lubricin. HIF-1α gene silencing was achieved by electroporatic transfer into ATDC5 cells. A low oxygen tension reduced lubricin gene expression levels in bovine superficial chondrocytes, TGF-β1-treated middle/deep zone chondrocytes, and TGF-β1-treated ATDC5 cells. Lubricin expression in explant cartilage was also suppressed under hypoxia. HIF-1α gene silencing in ATDC5 cells attenuated the lubricin expression response to the oxygen tension. These results corroborate with previous studies that the oxygen tension regulates lubricin gene expression and suggest that HIF-1α plays an important role in this regulation. The normal distribution of lubricin in articular cartilage may be due to the hypoxic oxygen environment of cartilage as it is an avascular tissue. An oxygen tension gradient may be a key factor for engineering cartilage tissue with a layered morphology.

  6. The effect of vesicle shape, line tension, and lateral tension on membrane-binding proteins

    NASA Astrophysics Data System (ADS)

    Hutchison, Jaime B.

    Model membranes allow for the exploration of complex biological phenomena with simple, controllable components. In this thesis we employ model membranes to determine the effect of vesicle properties such as line tension, lateral tension, and shape on membrane-binding proteins. We find that line tension at the boundary between domains in a phase separated vesicle can accumulate model membrane-binding proteins (green fluorescent protein with a histidine tag), and that those proteins can, in turn, alter vesicle shape. These results suggest that domains in biological membranes may enhance the local concentration of membrane-bound proteins and thus alter protein function. We also explore how membrane mechanical and chemical properties alter the function of the N-BAR domain of amphiphysin, a membrane-binding protein implicated in endocytosis. We find that negatively charged lipids are necessary for N-BAR binding to membranes at detectable levels, and that, at least for some lipid species, binding may be cooperative. Measurements of N-BAR binding as a function of vesicle tension reveal that modest membrane tension of around 2 mN/m, corresponding to a strain of around 1%, strongly increases N-BAR binding. We attribute this increase in binding with tension to the insertion of N-BAR's N-terminal amphipathic helix into the membrane which increases the membrane area. We propose that N-BAR, which was previously described as being able to sense membrane curvature, may be sensing strain instead. Measurements of membrane deformation by N-BAR as a function of membrane tension reveal that tension can hinder membrane deformation. Thus, tension may favor N-BAR binding yet suppress membrane deformation/tubulation, which requires work against tension. These results suggest that membrane tension, a parameter that is often not controlled in model membranes but is tightly controlled in biological cells, may be important in regulating protein binding and assembly and, hence, protein

  7. Preservice elementary teachers' development of pedagogical design capacity for inquiry---an activity-theoretical perspective

    NASA Astrophysics Data System (ADS)

    Forbes, Cory T.

    Preservice elementary teachers need to begin developing their pedagogical design capacities for inquiry by learning how to translate their conceptions of inquiry into classroom practice through the adaptation and enactment of curriculum materials. Using both qualitative and quantitative research methods, I draw upon cultural-historical activity theory (CHAT) to investigate preservice elementary teachers' curriculum design and development of pedagogical design capacity for inquiry during the final year of their teacher education program. This study involved analysis of curricular artifacts and survey data from 46 prospective elementary teachers in two sections of an undergraduate elementary science teaching methods course, as well as interviews, observational fieldnotes, reflective journals, and other artifacts from four preservice teachers from this larger group studied during the methods and student teaching semesters. Results show that preservice teachers were able to translate their espoused inquiry frameworks into planned and enacted science lessons. This involved adapting existing curriculum materials to better promote specific inquiry practices, but also to fundamentally shift the nature of classroom science. The preservice teachers' curriculum design efforts were constrained, however, by features of their institutional contexts and subject to emergent tensions. In attempting to resolve these tensions through curriculum design for inquiry, the preservice teachers ultimately articulated a fundamental contradiction between two distinct and competing visions for classroom inquiry: traditional classroom science, which promotes students' reproduction of scientific explanations by objectifying students, and a novel form of classroom inquiry that repositions students as contributing community members involved in the co-construction of knowledge through lesson-specific shared problem-spaces. For each of the preservice teachers, this contradiction had important

  8. Tension band wiring of the olecranon: is it really a dynamic principle of osteosynthesis?

    PubMed

    Brink, P R G; Windolf, M; de Boer, P; Brianza, S; Braunstein, V; Schwieger, K

    2013-04-01

    The tension band principle as applied to transverse olecranon fractures fixed by tension band wiring is based on the premise that distraction forces on the outer cortex of the ulna during elbow flexion are converted to compression forces on the articular surface of the olecranon at the fracture site. In view of some clinical outcomes, where hardware failure and secondary dislocations occur, the question arises if the dynamic compression theory is correct. Compressive forces during active flexion and extension after tension band wiring of a transverse osteotomy of the olecranon were measured in 6 fresh frozen human cadaveric models using a pressure-sensor in the osteotomy gap. We could collect 30 measurements during active flexion and 30 during active extension. Active flexion did not cause any compressive forces in the osteotomy gap. Extension with the humerus in an upright position and the elbow actively extended causes some compression (0.37-0.51 MPa) at the articular surface comparing with active flexion (0.2 MPa) due to gravity forces. Posterior, there was no significant pressure difference observed (0.41-0.45 versus 0.36-0.32 MPa) between active flexion and extension. The tension band wiring principle only exists during active extension in a range of 30-120° of flexion of the elbow. Postoperative exercise programs should be modified in order to prevent loss of compression at the fracture site of transverse olecranon fractures, treated with tension band wiring when the elbow is mobilised.

  9. Demographic tensions in Central America.

    PubMed

    1986-08-01

    disproportionately benefits high and middle income groups, thereby widening the already large gap between rich and poor. Average per capita income for the poorest 20% of Central Americans is $90 a year (in 1970 US dollars); over half subsist on an average of $200 a year. Central America's economic crisis is further intensified by the marked increase in the economically active population. Doubling in size from about 2.1 million in 1970 to 4.2 million in 1985, the labor force increasingly pressures an economy already weakened by high unemployment and underemployment. Socioeconomically advanced Costa Rica and Panama are Central America's notable exceptions. Life expectancy at birth and infant mortality rates for these better off countries, e.g., are comparable to those of developed countries. Costa Ricans enjoy the most equitable distributional income of all Central Americans. Panama's income differential is 1 of the widest in the world, but its relative wealth affords more for each of its citizens.

  10. The effects of femoral neck cut, cable tension, and muscles forces on the greater trochanter fixation.

    PubMed

    Petit, Yvan; Cloutier, Luc P; Duke, Kajsa; Laflamme, G Yves

    2012-04-01

    Greater trochanter (GT) stabilization techniques following a fracture or an osteotomy are still showing high levels of postoperative complications. Understanding the effect of femoral neck cut placement, cable tension and muscles forces on GT fragment displacements could help surgeons optimize their techniques. A 3D finite element model has been developed to evaluate, through a statistical experimental design, the impact of the above variables on the GT fragment gap and sliding displacements. Muscles forces were simulating typical daily activities. Stresses were also investigated. The femoral neck cut placement had the most significant effect on the fragment displacement. Lowering it by 5 mm increased the gap and sliding fragment displacements by 288 and 128 %, respectively. Excessive cable tightening provided no significant reduction in fragment displacement. Muscle activities increased the gap and the sliding displacements for all muscle configurations. The maximum total displacement of 0.41 mm was present with a 10 mm femoral neck cut, a cable tension of 178 N, and stair climbing. Caution must be used not to over tighten the cables as the potential damage caused by the increased stress is more significant than any reduction in fragment displacement. Furthermore, preservation of the contact area is important for GT stabilization.

  11. Myosin light chain kinase regulates cell polarization independently of membrane tension or Rho kinase

    PubMed Central

    Lou, Sunny S.; Diz-Muñoz, Alba; Weiner, Orion D.; Fletcher, Daniel A.

    2015-01-01

    Cells polarize to a single front and rear to achieve rapid actin-based motility, but the mechanisms preventing the formation of multiple fronts are unclear. We developed embryonic zebrafish keratocytes as a model system for investigating establishment of a single axis. We observed that, although keratocytes from 2 d postfertilization (dpf) embryos resembled canonical fan-shaped keratocytes, keratocytes from 4 dpf embryos often formed multiple protrusions despite unchanged membrane tension. Using genomic, genetic, and pharmacological approaches, we determined that the multiple-protrusion phenotype was primarily due to increased myosin light chain kinase (MLCK) expression. MLCK activity influences cell polarity by increasing myosin accumulation in lamellipodia, which locally decreases protrusion lifetime, limiting lamellipodial size and allowing for multiple protrusions to coexist within the context of membrane tension limiting protrusion globally. In contrast, Rho kinase (ROCK) regulates myosin accumulation at the cell rear and does not determine protrusion size. These results suggest a novel MLCK-specific mechanism for controlling cell polarity via regulation of myosin activity in protrusions. PMID:25918227

  12. Mechanisms underlying spontaneous patterned activity in developing neural circuits

    PubMed Central

    Blankenship, Aaron G.; Feller, Marla B.

    2010-01-01

    Patterned, spontaneous activity occurs in many developing neural circuits, including the retina, the cochlea, the spinal cord, the cerebellum and the hippocampus, where it provides signals that are important for the development of neurons and their connections. Despite differences in adult architecture and output across these various circuits, the patterns of spontaneous network activity and the mechanisms that generate it are remarkably similar and can include a depolarizing action of GABA, transient synaptic connections, extrasynaptic transmission, gap junction coupling and the presence of pacemaker-like neurons. Interestingly, spontaneous activity is robust; if one element of a circuit is disrupted another will generate similar activity. This research suggests that developing neural circuits exhibit transient and tunable features that maintain a source of correlated activity during critical stages of development. PMID:19953103

  13. Reduced-activation steels: Future development for improved creep strength

    NASA Astrophysics Data System (ADS)

    Klueh, R. L.

    2008-08-01

    Reduced-activation steels for fusion applications were developed in the 1980s to replace the elevated-temperature commercial steels first considered. The new steels were patterned after the commercial steels, with the objective that the new steels have yield stress and ultimate tensile strength and impact toughness in a Charpy test comparable to or better than the steels they replaced. That objective was achieved in reduced-activation steels developed in Japan, Europe, and the United States. Although tensile and impact toughness of the reduced-activation steels exceed those of the commercial steels they were patterned after, their creep-rupture properties are inferior to some commercial steels they replaced. They are even more inferior to commercial steels developed since the 1980s. In this paper, compositional differences between reduced-activation steels and new commercial steels are examined, and compositions are proposed for development of new-and-improved reduced-activation steels.

  14. Tension dynamics in semiflexible polymers. II. Scaling solutions and applications.

    PubMed

    Hallatschek, Oskar; Frey, Erwin; Kroy, Klaus

    2007-03-01

    In part I [O. Hallatschek, preceding paper, Phys. Rev. E 75, 031905 (2007)] of this contribution, a systematic coarse-grained description of the dynamics of a weakly bending semiflexible polymer was developed. Here, we discuss analytical solutions of the established deterministic partial integro-differential equation for the spatiotemporal relaxation of the backbone tension. For prototypal experimental situations, such as the sudden application or release of a strong external pulling force, it is demonstrated that the tensile dynamics reflects the self-affine conformational fluctuation spectrum in a variety of intermediate asymptotic power laws. Detailed and explicit analytical predictions for the tension propagation and relaxation and corresponding results for common observables, such as the end-to-end distance, are obtained.

  15. Effects of neutral posture on muscle tension during computer use.

    PubMed

    Dowler, E; Kappes, B; Fenaughty, A; Pemberton, G

    2001-01-01

    This study focused on developing a new approach to seated work positions was conducted on 67 office workers who use a Visual Display Terminal (VDT) as a major function of their working day. Muscle tension was measured by surface electromyography (sEMG) while participants were asked to adopt 4 selected working postures. Pain was measured before and after ergonomic intervention on the Nordic scale, which was modified for this study. Adjustable workstations were used to place participants in desired positions during the clinical testing sessions and the extended intervention period. Results indicate the effects of this ergonomic intervention may have positive effects on muscle tension and pain, significant enough to encourage employers to implement training and workstation modifications following these guidelines.

  16. Creative Activity in Conception of Sustainable Development Education

    ERIC Educational Resources Information Center

    Slahova, Aleksandra; Savvina, Jolanta; Cacka, Maris; Volonte, Ilze

    2007-01-01

    Purpose: The purpose of this paper is to reflect on the stages in the development of creative activity considering the distinctive features of all stages and the modes of dynamics of the development of a creative person. Design/methodology/approach: The paper analyses scientific investigations and pedagogical experiences in order to develop the…

  17. Minimum Activities for National Library and Bibliographic Development.

    ERIC Educational Resources Information Center

    Harvey, John F.

    In this document the author attempts to set forth the activities, items, or criteria susceptible of development in librarianship, information science, and bibliography. The list attempts to include all facets of a reasonably extensive development, one which no country has quite reached. On the other hand, among highly developed countries, progress…

  18. Tension Distribution in a Tendon-Driven Robotic Finger

    NASA Technical Reports Server (NTRS)

    Abdallah, Muhammad E. (Inventor); Platt, Robert (Inventor); Wampler, II, Charles W. (Inventor)

    2013-01-01

    A method is provided for distributing tension among tendons of a tendon-driven finger in a robotic system, wherein the finger characterized by n degrees of freedom and n+1 tendons. The method includes determining a maximum functional tension and a minimum functional tension of each tendon of the finger, and then using a controller to distribute tension among the tendons, such that each tendon is assigned a tension value less than the maximum functional tension and greater than or equal to the minimum functional tension. The method satisfies the minimum functional tension while minimizing the internal tension in the robotic system, and satisfies the maximum functional tension without introducing a coupled disturbance to the joint torques. A robotic system includes a robot having at least one tendon-driven finger characterized by n degrees of freedom and n+1 tendons, and a controller having an algorithm for controlling the tendons as set forth above.

  19. [The myth of tension-type headache].

    PubMed

    Diaz-Insa, Samuel

    2014-03-10

    Tension-type headache is an entity recognised by the International Headache Society in its International Headache Classification. The limits of this condition, however, are somewhat fuzzy and poorly defined, and its diagnostic criteria are a sort of negation of the symptoms of migraine. In this review we are especially interested in highlighting the diagnostic vagueness in patients with chronic tension-type headache. This refers, above all, to those with a clear history of migraine and who continue to suffer a number of crises with symptoms of migraine, although they have headaches with tension-type features on a daily basis. Emphasis will be placed on the novel concept of chronic migraine which, today, can include these patients, and has not only diagnostic but also, and above all, therapeutic implications. Tension-type headache is a clinical syndrome that probably covers a series of entities with important aetiopathogenic differences from one to another and, perhaps sometime in the future, many patients who are now labelled as having been diagnosed with this condition will be classified further as having other better-defined diseases. In any case, although it might sound like a myth or just pie-in-the-sky, the tension-type headache is still needed to encompass these entities that are lacking any better-defined diagnoses.

  20. Canada's physical activity guides: background, process, and development.

    PubMed

    Sharratt, Michael T; Hearst, William E

    2007-01-01

    This historical background paper chronicles the major events leading to the development of Canada's physical activity guides (for children, youth, adults, and older adults). The paper outlines the process and the steps used, including information (where applicable) regarding national partners, project administration, Health Canada communications, product development, endorsement, distribution and implementation, collateral activities, media relations and evaluation framework. Brief summaries of the science that led to the recommended guidelines are included. The paper also summarizes the various physical activity guide assessment and evaluation projects and their findings, particularly as they relate to research carried out on Canada's physical activity guides for children and youth (and the associated support resources).

  1. Oxygen Tension Regulates the Expression of Angiogenesis Factor by Macrophages

    NASA Astrophysics Data System (ADS)

    Knighton, David R.; Hunt, Thomas K.; Scheuenstuhl, Heinz; Halliday, Betty J.; Werb, Zena; Banda, Michael J.

    1983-09-01

    When cultured in a hypoxic environment similar to that found in the center of a wound, macrophages secreted active angiogenesis factor into the medium. Under conditions similar to those of well-oxygenated tissue, macrophages did not secrete active angiogenesis factor. Macrophages that secreted the factor at hypoxic conditions stopped secreting it when returned to room air. Thus the control of angiogenesis in wound healing may be the result of macrophages responding to tissue oxygen tension without the necessity of interacting with other cell types or biochemical signals.

  2. Investigation of the interfacial tension of complex coacervates using field-theoretic simulations

    SciTech Connect

    Kumar, Rajeev

    2012-01-01

    Complex coacervation, a liquid-liquid phase separation that occurs when two oppositely charged polyelectrolytes are mixed in a solution, has the potential to be exploited for many emerging applications including wet adhesives and drug delivery vehicles. The ultra-low interfacial tension of coacervate systems against water is critical for such applications, and it would be advantageous if molecular models could be used to characterize how various system properties (e.g., salt concentration) affect the interfacial tension. In this article we use field-theoretic simulations to characterize the interfacial tension between a complex coacervate and its supernatant. After demonstrating that our model is free of ultraviolet divergences (calculated properties converge as the collocation grid is refined), we develop two methods for calculating the interfacial tension from field-theoretic simulations. One method relies on the mechanical interpretation of the interfacial tension as the interfacial pressure, and the second method estimates the change in free energy as the area between the two phases is changed. These are the first calculations of the interfacial tension from full field theoretic simulation of which we are aware, and both the magnitude and scaling behaviors of our calculated interfacial tension agree with recent experiments.

  3. Stabilization of electrical sensing properties of carbon fiber sensors using pre-tensioning approach

    NASA Astrophysics Data System (ADS)

    Saifeldeen, M. A.; Fouad, N.; Huang, H.; Wu, Z. S.

    2017-01-01

    Owing to fabrication defects in carbon fiber (CF) tows, the unevenness of fiber roves, such as local bends, misalignments, and skewness, results in irregular distribution of the electrical resistance in the transverse direction along the gauge length of a sensor, which affects its performance. In this study, a pre-tension approach was developed according to the creep mechanism of composites to straighten the CFs. In addition, the resin relaxation was controlled by tensioning the fibers during and after hardening of the epoxy resin using a double-tension method to enhance the electrical sensing properties of long gauge carbon fiber line (CFL) strain sensors. Different levels of sustained tensile stresses were studied to obtain the optimal tensile stress level both during and after hardening to be applied in the double-tension method. The results of static and dynamic tests showed that the double-tension technique could significantly straighten the fibers, and stabilize the transverse connections of CFL sensors in the case of tensioning the fibers during and after hardening under a sustained stress of 60% of the ultimate tensile stress of the CFs. The proposed double-tension method was utilized to improve the response of the CFL sensors with short gauge lengths.

  4. The effect of line tension on the shape of liquid menisci near stripwise heterogeneous walls.

    PubMed

    Hoorfar, M; Amirfazli, A; Gaydos, J A; Neumann, A W

    2005-06-30

    Most attempts for the measurement of line tension in solid-liquid-vapor systems are based on the drop size dependence of contact angles of sessile drops on smooth, homogeneous solid surfaces. Despite being a well-defined thermodynamic quantity, there are still significant discrepancies in both the magnitude and sign of line tension reported in different experimental arrangements and theoretical studies. In order to broaden the scope of experimental studies of line tension, a non-axisymmetric system, i.e., a stripwise heterogeneous wall arrangement, was considered. A numerical scheme has been developed to solve simultaneously both the modified Young equation and the Laplace equation of capillarity for such a stripwise wall and to generate a series of theoretical contact lines for non-zero line tension values. These theoretical curves can be compared to experimental profiles to determine line tension. The preliminary comparison of these curves with an experimental curve suggests that the line tension value is on the order of 10(-6) (J/m), in agreement with values obtained from drop size dependence of contact angle studies. The comparison also shows that line tension in such systems cannot be as low as 10(-10) (J/m), i.e., the order of the magnitude obtained from some theoretical studies and experimental approaches.

  5. Pluralistic Tensions in Expatriating Managers

    ERIC Educational Resources Information Center

    Perkins, Stephen J.; Daste, Romain

    2007-01-01

    Purpose--The purpose of this article is to enhance understanding of influences on interaction between corporate personnel and development specialists and line functions associated with expatriating managers. Line managers are expected to accept greater responsibility for people management and development. But line managers' strategies for managing…

  6. Retinal waves coordinate patterned activity throughout the developing visual system

    PubMed Central

    Ackman, James B.; Burbridge, Timothy J.; Crair, Michael C.

    2014-01-01

    Summary The morphologic and functional development of the vertebrate nervous system is initially governed by genetic factors and subsequently refined by neuronal activity. However, fundamental features of the nervous system emerge before sensory experience is possible. Thus, activity-dependent development occurring before the onset of experience must be driven by spontaneous activity, but the origin and nature of activity in vivo remains largely untested. Here we use optical methods to demonstrate in live neonatal mice that waves of spontaneous retinal activity are present and propagate throughout the entire visual system before eye opening. This patterned activity encompassed the visual field, relied on cholinergic neurotransmission, preferentially initiated in the binocular retina, and exhibited spatiotemporal correlations between the two hemispheres. Retinal waves were the primary source of activity in the midbrain and primary visual cortex, but only modulated ongoing activity in secondary visual areas. Thus, spontaneous retinal activity is transmitted through the entire visual system and carries patterned information capable of guiding the activity-dependent development of complex intra- and inter- hemispheric circuits before the onset of vision. PMID:23060192

  7. Retinal waves coordinate patterned activity throughout the developing visual system.

    PubMed

    Ackman, James B; Burbridge, Timothy J; Crair, Michael C

    2012-10-11

    The morphological and functional development of the vertebrate nervous system is initially governed by genetic factors and subsequently refined by neuronal activity. However, fundamental features of the nervous system emerge before sensory experience is possible. Thus, activity-dependent development occurring before the onset of experience must be driven by spontaneous activity, but the origin and nature of activity in vivo remains largely untested. Here we use optical methods to show in live neonatal mice that waves of spontaneous retinal activity are present and propagate throughout the entire visual system before eye opening. This patterned activity encompassed the visual field, relied on cholinergic neurotransmission, preferentially initiated in the binocular retina and exhibited spatiotemporal correlations between the two hemispheres. Retinal waves were the primary source of activity in the midbrain and primary visual cortex, but only modulated ongoing activity in secondary visual areas. Thus, spontaneous retinal activity is transmitted through the entire visual system and carries patterned information capable of guiding the activity-dependent development of complex intra- and inter-hemispheric circuits before the onset of vision.

  8. Experimental Verification of a Progressive Damage Model for IM7/5260 Laminates Subjected to Tension-Tension Fatigue

    NASA Technical Reports Server (NTRS)

    Coats, Timothy W.; Harris, Charles E.

    1995-01-01

    The durability and damage tolerance of laminated composites are critical design considerations for airframe composite structures. Therefore, the ability to model damage initiation and growth and predict the life of laminated composites is necessary to achieve structurally efficient and economical designs. The purpose of this research is to experimentally verify the application of a continuum damage model to predict progressive damage development in a toughened material system. Damage due to monotonic and tension-tension fatigue was documented for IM7/5260 graphite/bismaleimide laminates. Crack density and delamination surface area were used to calculate matrix cracking and delamination internal state variables to predict stiffness loss in unnotched laminates. A damage dependent finite element code predicted the stiffness loss for notched laminates with good agreement to experimental data. It was concluded that the continuum damage model can adequately predict matrix damage progression in notched and unnotched laminates as a function of loading history and laminate stacking sequence.

  9. Carbon speciation and surface tension of fog

    USGS Publications Warehouse

    Capel, P.D.; Gunde, R.; Zurcher, F.; Giger, W.

    1990-01-01

    The speciation of carbon (dissolved/particulate, organic/inorganic) and surface tension of a number of radiation fogs from the urban area of Zurich, Switzerland, were measured. The carbon species were dominated by "dissolved" organic carbon (DOC; i.e., the fraction that passes through a filter), which was typically present at levels of 40-200 mg/L. Less than 10% of the DOC was identified as specific individual organic compounds. Particulate organic carbon (POC) accounted for 26-41% of the mass of the particles, but usually less than 10% of the total organic carbon mass. Inorganic carbon species were relatively minor. The surface tensions of all the measured samples were less than pure water and were correlated with their DOC concentrations. The combination of high DOC and POC and low surface tension suggests a mechanism for the concentration of hydrophobic organic contaminants in the fog droplet, which have been observed by numerous investigators. ?? 1990 American Chemical Society.

  10. Tension Stiffened and Tendon Actuated Manipulator

    NASA Technical Reports Server (NTRS)

    Doggett, William R. (Inventor); Dorsey, John T. (Inventor); Ganoe, George G. (Inventor); King, Bruce D. (Inventor); Jones, Thomas C. (Inventor); Mercer, Charles D. (Inventor); Corbin, Cole K. (Inventor)

    2015-01-01

    A tension stiffened and tendon actuated manipulator is provided performing robotic-like movements when acquiring a payload. The manipulator design can be adapted for use in-space, lunar or other planetary installations as it is readily configurable for acquiring and precisely manipulating a payload in both a zero-g environment and in an environment with a gravity field. The manipulator includes a plurality of link arms, a hinge connecting adjacent link arms together to allow the adjacent link arms to rotate relative to each other and a cable actuation and tensioning system provided between adjacent link arms. The cable actuation and tensioning system includes a spreader arm and a plurality of driven and non-driven elements attached to the link arms and the spreader arm. At least one cable is routed around the driven and non-driven elements for actuating the hinge.

  11. Elastic properties and mechanical tension of graphene

    NASA Astrophysics Data System (ADS)

    Ramírez, R.; Herrero, C. P.

    2017-01-01

    Room-temperature simulations of graphene have been performed as a function of the mechanical tension of the layer. Finite-size effects are accurately reproduced by an acoustic dispersion law for the out-of-plane vibrations that, in the long-wave limit, behaves as ρ ω2=σ k2+κ k4 . The fluctuation tension σ is finite (˜0.1 N/m) even when the external mechanical tension vanishes. Transverse vibrations imply a duplicity in the definition of the elastic constants of the layer, as observables related to the real area of the surface may differ from those related to the in-plane projected area. This duplicity explains the variability of experimental data on the Young modulus of graphene based on electron spectroscopy, interferometric profilometry, and indentation experiments.

  12. Acoustic Emission Transducers: Calibration Activities and Transducer Development.

    DTIC Science & Technology

    2014-09-26

    transducer calibration and development activities -j at NBS is summiarized. DO Fo"� roiion or olv as is OBSOLETE DOS/N 0 102. LP.60 4. 6601...developed. This development was partially supported by the Electric Power Research Institute and the Office of Naval Research. The calibration subjects the...and tangential components of motion must be measured tb describe the dynamic displacement at a point on a surface. We previously have developed the NBS

  13. DEVELOPMENT OF STRUCTURE ACTIVITY RELATIONSHIPS FOR ASSESSING ECOLOGICAL RISKS

    EPA Science Inventory

    In the field of environmental toxicology, structure activity relationships (SARs) have developed as scientifically-credible tools for predicting the effects of chemicals when little or no empirical data are available.

  14. Cdc42 controls the dilation of the exocytotic fusion pore by regulating membrane tension

    PubMed Central

    Bretou, Marine; Jouannot, Ouardane; Fanget, Isabelle; Pierobon, Paolo; Larochette, Nathanaël; Gestraud, Pierre; Guillon, Marc; Emiliani, Valentina; Gasman, Stéphane; Desnos, Claire; Lennon-Duménil, Ana-Maria; Darchen, François

    2014-01-01

    Membrane fusion underlies multiple processes, including exocytosis of hormones and neurotransmitters. Membrane fusion starts with the formation of a narrow fusion pore. Radial expansion of this pore completes the process and allows fast release of secretory compounds, but this step remains poorly understood. Here we show that inhibiting the expression of the small GTPase Cdc42 or preventing its activation with a dominant negative Cdc42 construct in human neuroendocrine cells impaired the release process by compromising fusion pore enlargement. Consequently the mode of vesicle exocytosis was shifted from full-collapse fusion to kiss-and-run. Remarkably, Cdc42-knockdown cells showed reduced membrane tension, and the artificial increase of membrane tension restored fusion pore enlargement. Moreover, inhibiting the motor protein myosin II by blebbistatin decreased membrane tension, as well as fusion pore dilation. We conclude that membrane tension is the driving force for fusion pore dilation and that Cdc42 is a key regulator of this force. PMID:25143404

  15. Motor Cortex Activity Organizes the Developing Rubrospinal System

    PubMed Central

    Williams, Preston T.J.A.

    2015-01-01

    The corticospinal and rubrospinal systems function in skilled movement control. A key question is how do these systems develop the capacity to coordinate their motor functions and, in turn, if the red nucleus/rubrospinal tract (RN/RST) compensates for developmental corticospinal injury? We used the cat to investigate whether the developing rubrospinal system is shaped by activity-dependent interactions with the developing corticospinal system. We unilaterally inactivated M1 by muscimol microinfusion between postnatal weeks 5 and 7 to examine activity-dependent interactions and whether the RN/RST compensates for corticospinal tract (CST) developmental motor impairments and CST misprojections after M1 inactivation. We examined the RN motor map and RST cervical projections at 7 weeks of age, while the corticospinal system was inactivated, and at 14 weeks, after activity returned. During M1 inactivation, the RN on the same side showed normal RST projections and reduced motor thresholds, suggestive of precocious development. By contrast, the RN on the untreated/active M1 side showed sparse RST projections and an immature motor map. After M1 activity returned later in adolescent cat development, RN on the active M1/CST side continued to show a substantial loss of spinal terminations and an impaired motor map. RN/RST on the inactivated side regressed to a smaller map and fewer axons. Our findings suggest that the developing rubrospinal system is under activity-dependent regulation by the corticospinal system for establishing mature RST connections and RN motor map. The lack of RS compensation on the non-inactivated side can be explained by development of ipsilateral misprojections from the active M1 that outcompete the RST. SIGNIFICANCE STATEMENT Skilled movements reflect the activity of multiple descending motor systems and their interactions with spinal motor circuits. Currently, there is little insight into whether motor systems interact during development to

  16. On the existence of small amplitude solitary waves with strong surface tension

    NASA Astrophysics Data System (ADS)

    Sachs, Robert L.

    An existence theory for small amplitude solitary waves with surface tension effects included is developed for large values of the surface tension parameter ( β > {1}/{3}). Using ideas of Beale, the Nash-Moser implicit function theorem is applied to justify the well-known approximation of Korteweg and deVries. Some of the recent results of Amick and Kirchgässner are thereby achieved more directly and additional insight obtained for the open case β < {1}/{3}.

  17. Students' difficulties with tension in massless strings

    NASA Astrophysics Data System (ADS)

    Flores-García, S.; Alfaro-Avena, L. L.; Chávez-Pierce, J. E.; Luna-González, J.; González-Quezada, M. D.

    2010-12-01

    Many students enrolled in introductory mechanics courses have difficulties with understanding the concept of static equilibrium. Some of these difficulties are related to the concept of force in the context of tension in massless strings. We identify three kinds of misconceptions: Students' beliefs that the angle of the string and proximity to the object are related to the tension. Students also use incorrect compensation arguments to reason about situations where both the angle and proximity change simultaneously. These difficulties were identified during investigations conducted in laboratory and lecture sessions at three universities in the United States and Mexico.

  18. Interactional Competence and the Development of Alignment Activity

    ERIC Educational Resources Information Center

    Dings, Abby

    2014-01-01

    Based on qualitative analysis of conversational interactions collected over the course of a Spanish language learner's academic year abroad, this article explores the development of interactional resources related to alignment activity in the learner's conversational participation. Alignment activity refers to the means interlocutors use…

  19. Universities and Economic Development Activities: A UK Regional Comparison

    ERIC Educational Resources Information Center

    Decter, Moira; Cave, Frank; Rose, Mary; Peers, Gill; Fogg, Helen; Smith, Susan M.

    2011-01-01

    A number of UK universities prioritize economic development or regeneration activities and for some of these universities such activities are the main focus of their knowledge transfer work. This study compares two regions of the UK--the North West and the South East of England--which have very different levels of economic performance.…

  20. The Dynamic Association between Motor Skill Development and Physical Activity

    ERIC Educational Resources Information Center

    Stodden, David F.; Goodway, Jacqueline D.

    2007-01-01

    Although significant attention has been given to promoting physical activity among children, little attention has been given to the developmental process of how children learn to move or to the changing role that motor skill development plays in children's physical activity levels as they grow. In order to successfully address the obesity…

  1. Breaking the Ice: Career Development Activities for Accounting Students

    ERIC Educational Resources Information Center

    Kilpatrick, Bob G.; Wilburn, Nancy L.

    2010-01-01

    This paper describes two co-curricular career development activities, mock interviews and speed networking that we provide for accounting majors at our university. The driving force behind both activities was to increase comfort levels for students when interacting with professionals and to enhance their job interview and networking skills.…

  2. Youth Development in After-School Leisure Activities

    ERIC Educational Resources Information Center

    Wilson, Denise M.; Gottfredson, Denise C.; Cross, Amanda B.; Rorie, Melissa; Connell, Nadine

    2010-01-01

    Leisure activities that occur outside of the school hours may facilitate positive youth development.The experiences of youth in three categories of activities (basketball and football, other sports, and nonsports) are examined in this study. Based on prior research, it is hypothesized that students participating in basketball and football will…

  3. Development and final design of FAME active array

    NASA Astrophysics Data System (ADS)

    Farkas, Szigfrid; Agócs, Tibor; Aitink-Kroes, Gabby; Bettonvil, Felix; Black, Martin; Hugot, Emmanuel; Jaskó, Attila; Miller, Chris; Schnetler, Hermine; van Duffelen, Farian; Venema, Lars

    2016-07-01

    FAME (Freeform Active Mirror Experiment - part of the FP7 OPTICON/FP7 development programme) intends to demonstrate the huge potential of active mirrors and freeform optical surfaces. Freeform active surfaces can help to address the new challenges of next generation astronomical instruments, which are bigger, more complex and have tighter specifications than their predecessors. The FAME design consists of a pre-formed, deformable thin mirror sheet with an active support system. The thin face sheet provides a close to final surface shape with very high surface quality. The active array provides the support, and through actuation, the control to achieve final surface shape accuracy. In this paper the development path, trade-offs and demonstrator design of the FAME active array is presented. The key step in the development process of the active array is the design of the mechanical structure and especially the optimization of the actuation node positions, where the actuator force is transmitted to the thin mirror sheet. This is crucial for the final performance of the mirror where the aim is to achieve an accurate surface shape, with low residual (high order) errors using the minimum number of actuators. These activities are based on the coupling of optical and mechanical engineering, using analytical and numerical methods, which results in an active array with optimized node positions and surface shape.

  4. Dynamic surface tension of surfactant TA: experiments and theory.

    PubMed

    Otis, D R; Ingenito, E P; Kamm, R D; Johnson, M

    1994-12-01

    A bubble surfactometer was used to measure the surface tension of an aqueous suspension of surfactant TA as a function of bubble area over a range of cycling rates and surfactant bulk concentrations. Results of the surface tension-interfacial area loops exhibited a rich variety of phenomena, the character of which varied systematically with frequency and bulk concentration. A model was developed to interpret and explain these data and for use in describing the dynamics of surface layers under more general circumstances. Surfactant was modeled as a single component with surface tension taken to depend on only the interfacial surfactant concentration. Two distinct mechanisms were considered for the exchange of surfactant between the bulk phase and interface. The first is described by a simple kinetic relationship for adsorption and desorption that pertains only when the interfacial concentration is below its maximum equilibrium value. The second mechanism is "squeeze-out" by which surfactant molecules are expelled from an interface compressed past a maximum packing state. The model provided good agreement with experimental measurements for cycling rates from 1 to 100 cycles/min and for bulk concentrations between 0.0073 and 7.3 mg/ml.

  5. Dynamic high-temperature Kolsky tension bar techniques

    SciTech Connect

    Song, Bo; Nelson, Kevin; Lipinski, Ronald; Bignell, John; Ulrich, George B; George, Easo P

    2015-01-01

    Kolsky tension bar techniques were modified for dynamic high-temperature tensile characterization of thin-sheet alloys. An induction coil heater was used to heat the specimen while a cooling system was applied to keep the bars at room temperature during heating. A preload system was developed to generate a small pretension load in the bar system during heating in order to compensate for the effect of thermal expansion generated in the high-temperature tensile specimen. A laser system was applied to directly measure the displacements at both ends of the tensile specimen in order to calculate the strain in the specimen. A pair of high-sensitivity semiconductor strain gages was used to measure the weak transmitted force due to the low flow stress in the thin specimen at elevated temperatures. As an example, the high-temperature Kolsky tension bar was used to characterize a DOP-26 iridium alloy in high-strain-rate tension at 860 s(-1)/1030 degrees C.

  6. Role of fascia in maintenance of muscle tension and pressure.

    PubMed

    Garfin, S R; Tipton, C M; Mubarak, S J; Woo, S L; Hargens, A R; Akeson, W H

    1981-08-01

    The effect of fasciotomy on muscle tension (measured by a force transducer attached to the tendon) and interstitial fluid pressure (measured by Wick catheters in the muscle belly) was studied in the anterolateral compartments of 13 dog hindlimbs. Muscle tension and pressure were monitored in the tibialis cranialis muscle after low- and high-frequency stimulation of the peroneal nerve to produce twitch- and tetanic-type contractions. Fasciotomy decreased muscle force during the low-frequency stimulation by 16% (35.3 +/- 4.9 to 28.4 +/- 3.9 N) and during the high-frequency stimulation by 10% (60.8 %/- 4.9 to 54.8 +/- 3.9 N). Muscle pressure decreased 50% after fasciotomy under both conditions, 15 +/- 2 to 6 +/- 1 mmHg and 84 +/- 17 to 41 +/- 8 mmHg), respectively. Repeated functional evaluations during the testing procedure indicated that muscle fatigue was not a major factor in these results. It was concluded that fascia is important in the development of muscle tension and changes in interstitial pressure. Furthermore, the results raised questions concerning the merits of performing a fasciotomy for athletes with a compartment syndrome.

  7. Greater hydrogen ion-induced depression of tension and velocity in skinned single fibres of rat fast than slow muscles.

    PubMed Central

    Metzger, J M; Moss, R L

    1987-01-01

    1. The effects of variations in pH between 7.00 and 6.20 on Ca2+ -activated tension development and maximum velocity of shortening (Vmax) were examined in skinned single skeletal fibres from rat slow-twitch soleus and fast-twitch superficial (s.v.l.) and deep (d.v.l.) regions of the vastus lateralis muscle. 2. At pH 6.50, Vmax was depressed to a similar degree in each of the soleus, d.v.l., and s.v.l. fibres. Lowering pH to 6.20 resulted in a further decline in Vmax in all fibres; however, differences between the slow fibres, identified by SDS-polyacrylamide gel electrophoresis, and fast fibres were apparent, with soleus retaining a significantly greater proportion of its control Vmax (0.83 +/- 0.03 in soleus vs. 0.69 +/- 0.03 in s.v.l.; mean +/- S.E.M.). 3. Maximum force production decreased significantly as pH was reduced. Peak force at pH 6.50, relative to that at pH 7.00, was significantly greater in soleus (0.80 +/- 0.01) than in the s.v.l. (0.75 +/- 0.01) fibres. At pH 6.20 these differences between slow and fast fibres were still greater, in that soleus fibres generated significantly greater relative forces (0.73 +/- 0.01) than did d.v.l. (0.67 +/- 0.02) or s.v.l. (0.63 +/- 0.02) fibres. 4. As pH was lowered the tension-pCa relationship shifted to the right (i.e. to higher [Ca2+]), indicating a reduction in the Ca2+ sensitivity of tension development. The [Ca2+] necessary to achieve half-maximal tension in both the slow- and fast-twitch fibres increased approximately 5-fold when pH was lowered from 7.00 to 6.20. Furthermore, in the case of the soleus, the Ca2+ threshold for tension development was 45 times greater at pH 6.20 than at pH 7.00, while in the fast-twitch fibres, this increase was 4-fold. 5. Increased [H+] differentially affected the steepness of the tension-pCa relationship between slow and fast fibres. As pH was lowered, the steepness of the lower portion of the tension-pCa curve increased in the soleus and decreased in d.v.l. and s

  8. Sarcomere overextension reduces stretch-induced tension loss in myofibrils of rabbit psoas.

    PubMed

    Panchangam, Appaji; Herzog, Walter

    2011-07-28

    Stretch-induced damage to skeletal muscles results in loss of isometric tension. Although there is no direct evidence, loss of tension has been implicitly assumed to be the consequence of permanent loss of myofilament overlap in some sarcomeres ('sarcomere overextension'). Using isolated myofibrils of rabbit psoas muscle (n=38; 6 control and 32 test specimens) at 12-15°C, we directly tested the idea that loss of tension following stretch is caused by sarcomere overextension. Experimental myofibrils were maximally activated at the edge of the descending limb (sarcomere length ∼ 2.9 μm) of the sarcomere length-tension relationship and then stretched by 1 μm sarcomere(-1) at a constant speed of 0.1 μms(-1)sarcomere(-1) to result in an average strain of 33.6 ± 0.9% (mean ± 1 SE). Myofibrils were immediately returned to the original lengths and relaxed. Isometric tension measured in a subsequent re-activation 3-5 min later was reduced by 24.6 ± 1.5% from its original value. In 22 out of the 32 test specimens, all sarcomeres maintained myofilament overlap, while in 10 myofibrils one or two sarcomeres were stretched permanently beyond myofilament overlap (>4.0 μm), and thus exhibited overextended sarcomeres. Loss of tension following stretch was significantly smaller in myofibrils with overextended sarcomeres compared to myofibrils with no overextended sarcomeres (19.5 ± 2.3% and 27.1 ± 1.8%, respectively; p=0.017). Combined, these results suggest that the loss of tension associated with stretch-induced damage can occur in the absence of sarcomere overextension and that sarcomere overextension limits rather than causes stretch-induced tension loss.

  9. Hospital chief executive officer perspective on professional development activities.

    PubMed

    Khaliq, Amir A; Walston, Stephen L

    2010-01-01

    A study was undertaken to develop understanding of hospital chief executive officers' (CEOs') perspectives concerning importance and impact of professional development activities in US hospitals. It was also intended to reveal CEO preferences for various modalities of professional development including membership in professional societies, attainment of credentials, and coaching by mentors. A mail survey of 582 hospital CEOs made use of a pilot-tested questionnaire with 30 close ended multipart questions. Results showed that most CEOs assigned a high level of importance to professional development and favored conferences, seminars, and networking opportunities, but low priority assigned to online activities such as webinars. They reported lending support to senior managers for participation in these activities by providing financial resources and by allowing time off to engage in these activities. The respondents indicated that the importance of various modalities of professional development has either increased or remained high over the recent 5 years. Conclusions suggest that verifiable quantitative data are needed for understanding of the frequency of participation and resource commitment of health care organizations toward the professional development of CEOs and senior managers. The results of this perceptual study reveal a high level of importance accorded to various forms of professional development activities by the participating CEOs.

  10. Heat shock factor 2 is activated during mouse heart development.

    PubMed

    Eriksson, M; Jokinen, E; Sistonen, L; Leppä, S

    2000-08-01

    Two members of the heat shock transcription factor family, HSF1 and HSF2, have been identified as activators of mammalian heat shock gene expression. HSF1 acts as a classical stress-responsive factor, whereas HSF2 might play a role in embryogenesis, since it is active during pre- and post-implantation periods up to 15.5 days of mouse embryonic development. In this study, we analyzed HSF1 and HSF2 expression and activation during mouse heart formation. Our results show an abundant expression of HSF1 throughout heart development. In contrast, expression of the alternatively spliced HSF2-alpha and HSF2-beta, and an additional higher molecular weight isoform is strongly upregulated in the developing mouse heart at E11.5-12.5, a stage after which tubular heart has looped and chambers formed, and the myocardial walls are maturating and the valves differentiating. At the same developmental stage, HSF2 DNA-binding activity is transiently induced, whereas the weak HSE-binding activity, which is detected throughout heart development, consists primarily of HSF1. Interestingly, heat shock gene expression shows no temporal or spatial correlation with HSF2 expression and activation. Taken together, our results indicate that HSF2 activation is associated with specific stages of heart formation but is not involved in the regulation of inducible heat shock gene expression.

  11. Adult Learning Principles in Designing Learning Activities for Teacher Development

    ERIC Educational Resources Information Center

    Gravani, Maria N.

    2012-01-01

    The research reported in this paper is an investigation of the application of adult learning principles in designing learning activities for teachers' life-long development. The exploration is illustrated by qualitative data from a case study of adult educators' and adult learners' insights and experiences of a teacher development course organised…

  12. Development of Active Learning with Simulations and Games

    ERIC Educational Resources Information Center

    Zapalska, Alina; Brozik, Dallas; Rudd, Denis

    2012-01-01

    Educational games and simulations are excellent active learning tools that offer students hands-on experience. Little research is available on developing games and simulations and how teachers can be assisted in making their own games and simulations. In this context, the paper presents a multi-step process of how to develop games and simulations…

  13. Telomerase Activity is Downregulated Early During Human Brain Development

    PubMed Central

    Ishaq, Abbas; Hanson, Peter S.; Morris, Christopher M.; Saretzki, Gabriele

    2016-01-01

    Changes in hTERT splice variant expression have been proposed to facilitate the decrease of telomerase activity during fetal development in various human tissues. Here, we analyzed the expression of telomerase RNA (hTR), wild type and α-spliced hTERT in developing human fetal brain (post conception weeks, pcw, 6–19) and in young and old cortices using qPCR and correlated it to telomerase activity measured by TRAP assay. Decrease of telomerase activity occurred early during brain development and correlated strongest to decreased hTR expression. The expression of α-spliced hTERT increased between pcw 10 and 19, while that of wild type hTERT remained unchanged. Lack of expression differences between young and old cortices suggests that most changes seem to occur early during human brain development. Using in vitro differentiation of neural precursor stem cells (NPSCs) derived at pcw 6 we found a decrease in telomerase activity but no major expression changes in telomerase associated genes. Thus, they do not seem to model the mechanisms for the decrease in telomerase activity in fetal brains. Our results suggest that decreased hTR levels, as well as transient increase in α-spliced hTERT, might both contribute to downregulation of telomerase activity during early human brain development between 6 and 17 pcw. PMID:27322326

  14. Skeletal muscle is sensitive to the tension-time integral but not to the rate of change of tension, as assessed by mechanically induced signaling.

    PubMed

    Martineau, Louis C; Gardiner, Phillip F

    2002-05-01

    Mechanical forces regulate many cellular processes. Mechanotransduction, however, is poorly understood. In skeletal muscle, mechanical forces have a major impact on the regulation of cellular volume, yet the nature of the mechanical stimulation to which muscle is most sensitive is unknown. It was recently demonstrated that activation of the mechanically-sensitive kinase p54 jun-N-terminal-kinase (JNK), is a quantitative marker of mechanical stimulation in skeletal muscle. This marker was shown to be more sensitive to peak tension than to other tension-related parameters such as the tension-time integral (TTI) and the rate of change of tension (dT/dt). The purpose of the present study was to parcel out the contribution of TTI and dT/dt to mechanical stimulation of muscle under conditions of constant peak tension. The rat medial gastrocnemius in situ was subjected to one of four 5-min passive stretch protocols consisting of equal length excursions, but differing in displacement-time integral (4%, 40%, or 100%) and/or rate of stretch (0, 3, or 30 mm/s), and the resulting p54-JNK phosphorylation was assessed. A linear relationship between TTI and p54-JNK signaling was observed. However, no effect of dT/dt was observed. It is concluded that peak tension and TTI are necessary parameters for modeling the mechanical stimulus-response of muscle. Additionally, the mechanism of mechanotransduction is sensitive to peak tension and TTI, but not to dT/dt, and thus exhibits spring-like behavior. These findings may contribute to the refinement of disuse atrophy countermeasures.

  15. Rapid optimization of tension distribution for cable-driven parallel manipulators with redundant cables

    NASA Astrophysics Data System (ADS)

    Ouyang, Bo; Shang, Weiwei

    2016-03-01

    The solution of tension distributions is infinite for cable-driven parallel manipulators(CDPMs) with redundant cables. A rapid optimization method for determining the optimal tension distribution is presented. The new optimization method is primarily based on the geometry properties of a polyhedron and convex analysis. The computational efficiency of the optimization method is improved by the designed projection algorithm, and a fast algorithm is proposed to determine which two of the lines are intersected at the optimal point. Moreover, a method for avoiding the operating point on the lower tension limit is developed. Simulation experiments are implemented on a six degree-of-freedom(6-DOF) CDPM with eight cables, and the results indicate that the new method is one order of magnitude faster than the standard simplex method. The optimal distribution of tension distribution is thus rapidly established on real-time by the proposed method.

  16. Surface Tension of Organic Liquids Using the OPLS/AA Force Field.

    PubMed

    Zubillaga, Rafael A; Labastida, Ariana; Cruz, Bibiana; Martínez, Juan Carlos; Sánchez, Enrique; Alejandre, José

    2013-03-12

    Molecular dynamics simulations are performed to obtain the surface tension of 61 organic liquids using the OPLS/AA (all-atom optimized potential for liquid simulations). The force field parameters are the same as those recently used (Caleman et al. J. Chem. Theory Comput.2012, 8, 61) to determine several thermodynamic properties of 146 organic liquids. The correct evaluation of surface tension using slab simulations of liquids requires one to properly take into account the long-range interactions (Trukhymchuk and Alejandre J. Chem. Phys.1999, 111, 8510). In addition, the liquid density from slab simulations has to be the same as that obtained in liquid simulations at constant temperature and pressure. The new results of surface tensions from this work improve those reported by Caleman et al. The OPLS/AA force field gives good surface tensions compared with experimental data for most of the systems studied in this work, although it was developed to simulate liquids.

  17. Insertion Testing of Polyethylene Glycol Microneedle Array into Cultured Human Skin with Biaxial Tension

    NASA Astrophysics Data System (ADS)

    Takano, Naoki; Tachikawa, Hiroto; Miyano, Takaya; Nishiyabu, Kazuaki

    Aiming at the practical use of polyethylene glycol (PEG) microneedles for transdermal drug delivery system (DDS), a testing apparatus for their insertion into cultured human skin has been developed. To simulate the variety of conditions of human skin, biaxial tension can be applied to the cultured human skin. An adopted testing scheme to apply and control the biaxial tension is similar to the deep-draw forming technique. An attention was also paid to the short-time setup of small, thin and wet cultured skin. One dimensional array with four needles was inserted and influence of tension was discussed. It was found that tension, deflection of skin during insertion and original curvature of skin are the important parameters for microneedles array design.

  18. Structural Verification and Modeling of a Tension Cone Inflatable Aerodynamic Decelerator

    NASA Technical Reports Server (NTRS)

    Tanner, Christopher L.; Cruz, Juan R.; Braun, Robert D.

    2010-01-01

    Verification analyses were conducted on membrane structures pertaining to a tension cone inflatable aerodynamic decelerator using the analysis code LS-DYNA. The responses of three structures - a cylinder, torus, and tension shell - were compared against linear theory for various loading cases. Stress distribution, buckling behavior, and wrinkling behavior were investigated. In general, agreement between theory and LS-DYNA was very good for all cases investigated. These verification cases exposed the important effects of using a linear elastic liner in membrane structures under compression. Finally, a tension cone wind tunnel test article is modeled in LS-DYNA for which preliminary results are presented. Unlike data from supersonic wind tunnel testing, the segmented tension shell and torus experienced oscillatory behavior when subjected to a steady aerodynamic pressure distribution. This work is presented as a work in progress towards development of a fluid-structures interaction mechanism to investigate aeroelastic behavior of inflatable aerodynamic decelerators.

  19. Surface tension of aqueous lithium bromide solutions containing 1-octanol as a heat-transfer additive

    SciTech Connect

    Ishida, Kenji; Mori, Y.H.

    1996-11-01

    The surface tension of simulated heat-pump working fluids, aqueous solutions of lithium bromide containing 1-octanol, has been measured, for the first time using a recently developed technique (Ishida et al., Rev. Sci. Instrum. 64, 1,324 (1993)) which is inherently suitable for characterizing the surfactant solution surfaces from the aspects of thermodynamic adsorption equilibrium and adsorption kinetics. The measurement has revealed that even the highest-grade reagents of lithium bromide commercially available are not necessarily free from surfactant impurities. Obtained data on the surface tension vs 1-octanol concentration have been examined on the basis of an equilibrium adsorption model. Through the optimal fitting of the Langmuir-type surface equation of state to the data, they have calculated the surface tension vs surface excess relation and also the variation in surface tension vs 1-octanol concentration relation with the surface area per unit volume of a given solution.

  20. Localized type Volkmann's contracture treated with tendon transfer and tension-reduced early mobilization

    PubMed Central

    Kaji, Yoshio; Nakamura, Osamu; Yamaguchi, Konosuke; Tobiume, Sachiko; Yamamoto, Tetsuji

    2017-01-01

    Abstract Rationale: For localized type Volkmann's contracture, in which degeneration of the flexor digitorum profundus (FDP) muscle to one or two fingers and restriction of finger extension occur, dissection or excision of the affected muscle is usually recommended. However, these surgical procedures need relatively wide exposure of the muscle, because the FDP muscle is in the deep portion of the forearm. Patient concerns: In this report, the case of a 35-year-old woman with localized type Volkmann's contracture is presented. Her left forearm had been compressed with an industrial roller 4 months earlier, and severe flexion contracture of the long finger and mild flexion contracture of the ring finger developed gradually. Diagnoses: localized type Volkmann's contracture. Intervention: Five months after the injury, transection of the FDP tendon to the long finger and transfer of the transected tendon to the FDP tendon to the index finger was performed after adjusting the tonus of these two tendons using a small skin incision. This procedure was followed by a tension-reduced early mobilization technique in which a tension-reduced position of the tendon suture site was maintained by taping the long finger to the volar side of the index finger, and then immediate active range of motion (ROM) exercise was started. Outcomes: Within 9 weeks after surgery, full ROM had been regained. Lessons: Using the treatment procedure presented in this case report, a good clinical result was obtained in a minimally invasive manner. PMID:28072735

  1. A finite element model of the face including an orthotropic skin model under in vivo tension.

    PubMed

    Flynn, Cormac; Stavness, Ian; Lloyd, John; Fels, Sidney

    2015-01-01

    Computer models of the human face have the potential to be used as powerful tools in surgery simulation and animation development applications. While existing models accurately represent various anatomical features of the face, the representation of the skin and soft tissues is very simplified. A computer model of the face is proposed in which the skin is represented by an orthotropic hyperelastic constitutive model. The in vivo tension inherent in skin is also represented in the model. The model was tested by simulating several facial expressions by activating appropriate orofacial and jaw muscles. Previous experiments calculated the change in orientation of the long axis of elliptical wounds on patients' faces for wide opening of the mouth and an open-mouth smile (both 30(o)). These results were compared with the average change of maximum principal stress direction in the skin calculated in the face model for wide opening of the mouth (18(o)) and an open-mouth smile (25(o)). The displacements of landmarks on the face for four facial expressions were compared with experimental measurements in the literature. The corner of the mouth in the model experienced the largest displacement for each facial expression (∼11-14 mm). The simulated landmark displacements were within a standard deviation of the measured displacements. Increasing the skin stiffness and skin tension generally resulted in a reduction in landmark displacements upon facial expression.

  2. Tension Builds over AFT Reform Agenda

    ERIC Educational Resources Information Center

    Sawchuk, Stephen

    2012-01-01

    Can a teachers' union successfully be both a hardball-playing defender of its rights and a collaborative force for the common good? It is both a question of philosophy and, increasingly, one of policy direction for the American Federation of Teachers (AFT), whose biennial convention in Detroit showed delegates grappling with the tension between…

  3. Tenure Tensions: Out in the Enchanted Forest

    ERIC Educational Resources Information Center

    Tyler, Jo A.

    2010-01-01

    The tenure track in higher education represents a path shrouded in a fair degree of mystery. This essay provides the perspective of a middle-aged, second-career tenure track faculty member on the vagaries of progressing down the track as an out lesbian. Three dialectics that build tension into the process--covering-creating, evaluation-liberation,…

  4. Researchers as Evaluators: Tasks, Tensions and Politics

    ERIC Educational Resources Information Center

    Langfeldt, Liv; Kyvik, Svein

    2011-01-01

    Researchers undertake a number of different research evaluation tasks, taking up a substantial part of their research time--estimated to about one work month per year for a professor. This paper addresses the various evaluator roles and tasks researchers take on, and the tensions they involve. How the research evaluator role may conflict with the…

  5. Identity Tensions in Lesbian Intercollegiate Coaches

    ERIC Educational Resources Information Center

    Krane, Vikki; Barber, Heather

    2005-01-01

    Using social identity perspective, the authors investigated the experiences of 13 lesbian college coaches. Through semistructured interviews, the coaches revealed the daily identity tensions they experienced. There was constant negotiation between their social identities of "coach" and "lesbian." The social context of intercollegiate women's…

  6. Tension and relaxation in the individual.

    PubMed

    Newbury, C R

    1979-06-01

    Increasing materialism in society is resulting in more wide spread nervous tension in all age groups. While some degree of nervous tension is necessary in everyday living, its adverse effects require that we must learn to bring it under control. Total tension is shown to have two components: a controllable element arising from factors in the environment and the inbuilt uncontrollable residue which is basic in the individual temperament. The effects of excessive or uncontrolled stress can be classified as 1) emotional reactions such as neurotic behaviour (anxiety hypochondria, hysteria, phobia, depression obsessions and compulsions) or psychotic behaviour and 2) psychosomatic reactions (nervous asthma, headache, insomnia, heart attack). Nervous energy can be wastefully expended by such factors as loss of temper, wrong attitudes to work, job frustration and marital strains. Relaxation is the only positive way to control undesirable nervous tension and its techniques require to be learned. A number of techniques (progressive relaxation, differential relaxation, hypnosis, the use of biofeedback, Yoga and Transcendental Meditation) are described and their application to dental practice is discussed.

  7. Multiple Intelligences: Its Tensions and Possibilities

    ERIC Educational Resources Information Center

    Eisner, Elliot W.

    2004-01-01

    This article explores the tensions between Howard Gardner's theory of multiple intelligences and current educational policies emphasizing standardized and predictable outcomes. The article situates Gardner's theory within the historical interests among psychometricians in identifying those core processes that constitute human intelligence.…

  8. Navigating Teaching Tensions for Civic Learning

    ERIC Educational Resources Information Center

    Lowenstein, Ethan

    2010-01-01

    This article seeks to build on current and emerging conceptions of teacher expertise as they relate to education for civic engagement and social awareness in the university classroom context. I explore the notion of teaching tensions between vulnerability and authority, authenticity and distance, safety and challenge, disclosure and neutrality,…

  9. Tension in Chemistry and Its Contents.

    PubMed

    Hoffmann, Roald

    2015-01-01

    This article makes a case for a positive role of tension in the creative process in chemistry. I begin with an argument that there is an inherent tension in what makes molecules interesting--their positioning along various polar axes. One of these, the age-old differentiation between useful (to society and for personal profit) commercialization and pure understanding of molecules and their reactions is characteristic. The question of whether there are any bad molecules then leads me to ethical concerns in chemistry, and a particular working out of these in interactions of chemists in the Middle East. An analysis is made of the special tensions involved in publishing, especially in citation ethics; chemists publish a lot, so this is situation ethics worked out on a daily basis. I then find in the literature of psychology good evidence for the positive value of moderate stress in stimulating creativity. It is obvious that too much tension leads to distress, and there are some institutional aspects of chemistry that do not come out well here. But all in all, the dynamic middle is alive, and it leads to good new science.

  10. Tensions and Dilemmas in Leading Australia's Schools

    ERIC Educational Resources Information Center

    Gurr, David; Drysdale, Lawrie

    2012-01-01

    In this article we address several tensions and dilemmas that are impacting on Australian principals and other school leaders. The first section explores areas associated with improving teaching and learning and includes discussion of education trends, the construction of new learning environments and the implication of these for more…

  11. Five tensions between science and democracy

    SciTech Connect

    Guston, D.J.

    1995-12-31

    The historical aspects of dialogue between the scientific establishments and the congress are used to illustrate and define the continuing tensions between these parties since 1880. Five areas are addressed as how best to cope and deal with the issues which in all probability will not go away. 1 ref.

  12. "Jena Six": Case Study in Racial Tensions

    ERIC Educational Resources Information Center

    Maxwell, Lesli A.

    2007-01-01

    This article reports the racial tensions in Jena, Louisiana. On Aug. 31, 2006, school leaders in Jena, Louisiana, arrived to find two nooses hanging from an oak tree on the campus of Jena High School. The events since that incident--including the beating of a white student and resulting criminal charges against six black schoolmates that have…

  13. Measuring the surface tension of soap bubbles

    NASA Technical Reports Server (NTRS)

    Sorensen, Carl D.

    1992-01-01

    The objectives are for students to gain an understanding of surface tension, to see that pressure inside a small bubble is larger than that inside a large bubble. These concepts can be used to explain the behavior of liquid foams as well as precipitate coarsening and grain growth. Equipment, supplies, and procedures are explained.

  14. Tension in Chemistry and Its Contents

    PubMed Central

    Hoffmann, Roald

    2015-01-01

    This article makes a case for a positive role of tension in the creative process in chemistry. I begin with an argument that there is an inherent tension in what makes molecules interesting—their positioning along various polar axes. One of these, the age-old differentiation between useful (to society and for personal profit) commercialization and pure understanding of molecules and their reactions is characteristic. The question of whether there are any bad molecules then leads me to ethical concerns in chemistry, and a particular working out of these in interactions of chemists in the Middle East. An analysis is made of the special tensions involved in publishing, especially in citation ethics; chemists publish a lot, so this is situation ethics worked out on a daily basis. I then find in the literature of psychology good evidence for the positive value of moderate stress in stimulating creativity. It is obvious that too much tension leads to distress, and there are some institutional aspects of chemistry that do not come out well here. But all in all, the dynamic middle is alive, and it leads to good new science. PMID:26155730

  15. Rhetoric and Composition: A Necessary Tension.

    ERIC Educational Resources Information Center

    Chestek, Virginia L.

    Writing in Western culture requires mastery of both rhetorical theory and the expressive writing often promoted in composition studies, however great the conflict between them might be. The tension between these two poles can even be a source of excitement and motivation. Landmark composition studies such as those of James Britton and Janet Emig…

  16. Internationalization and Global Tension: Lessons From History

    ERIC Educational Resources Information Center

    Altbach, Philip G.; de Wit, Hans

    2015-01-01

    Increasing political and military tension in several parts of the world will inevitably affect international higher education. Nationalist, religious, and ideological conflicts challenge the original ideas of international cooperation and exchange in higher education as promoters of peace and mutual understanding and of global engagement. Since…

  17. Educational Leadership: Key Challenges and Ethical Tensions

    ERIC Educational Resources Information Center

    Duignan, Patrick

    2007-01-01

    "Educational Leadership" is a major research book on contemporary leadership challenges for educational leaders. In this groundbreaking new work, educational leaders in schools, including teachers, are provided with ways of analysing and resolving common but complex leadership challenges. Ethical tensions inherent in these challenges are…

  18. Education for sustainable development using indoor and outdoor activities

    NASA Astrophysics Data System (ADS)

    Žigon, Lenka

    2016-04-01

    Environmental education became an important part of our development in the last years. We put a lot of effort into a task how to improve students'values, skills, understanding and how to significantly enhance their learning and achievements regarding ecological problems. At the same time we also know that environmental learning is easier when our students have the opportunity to feel, see, touch, taste and smell the nature. Therefore teachers in my school develop regular access to the outdoors as a learning resource. Students understand the impact of their activities on the environment and they also like to participate in the nature protection. My school (Biotechnical Centre)is an example of educational centre where different research and development programes are strongly oriented to the sustainable development. Students are educated to become experts in biotechnology, agronomy, food technology and horticulture. At the same time they are educated how to care for the nature. The institution itself cooperates with different fields of economy (farms, food - baker industry, floristry, country design etc.). For these reasons the environmental education is an essential dimension of basic education focused on a sphere of interaction that lies at the root of personal and social development. We try to develop different outdoor activities through all the school year. These activities are: analyse the water quality; research waste water treatment plants; exploration of new food sources (like aquaponics - where fish and plants grow together); collecting plants with medical activities; care for the plants in the school yard; growing new plants in the poly tunnel; learning about unknown plants - especially when visiting national and regional parks; selling different things in the school shop - also for local citizens; participating in the world wide activity - "Keep the country tidy" etc. Students and teachers enjoy to participate in different outdoor activities; we both

  19. Numerical studies of surface tensions

    NASA Technical Reports Server (NTRS)

    Hung, R. J.

    1995-01-01

    Liquid-vapor (bubble) interface disturbances caused by various types of accelerations, including centrifugal, lateral and axial impulses, gravity gradient and g-jitter accelerations associated with spinning and slew motion in microgravity, are reviewed. Understanding of bubble deformations and fluctuations is important in the development of spacecraft orbital and attitude control techniques to secure its normal operation. This review discusses bubble deformations and oscillations driven by various forces in the microgravity environment. The corresponding bubble mass center fluctuations and slosh reaction forces and torques due to bubble deformations are also reviewed.

  20. Effect of Neck Formation on the Measurement of Dynamic Interfacial Tension in a Drop Volume Tensiometer

    PubMed

    Campanelli; Wang

    1997-06-15

    Dynamic interfacial tension values obtained by drop volume tensiometry will be affected under certain experimental conditions by the formation of a neck between the drop and the capillary tip. This phenomenon must be accounted for to obtain accurate values of interfacial tension. In this work, neck formation for a water-mineral oil system is studied under conditions where hydrodynamic effects can be neglected. A model originally developed for the determination of the surface tension of a suspended drop is modified for application to dynamic interfacial tensions of surfactant-containing liquids. The model relates apparent values of interfacial tension calculated from drops possessing necks to actual values. Experiments with Span 80 (sorbitan monooleate) and sodium dodecyl sulfate (SDS) surfactants in a mineral oil-water system are used to test the validity of the developed model. For the small tip diameter used, good agreement is obtained for Span 80 up to the critical micelle concentration, and for low concentrations of SDS, when the surfactant adsorption is diffusion-limited. In both cases, the neck diameter of the growing drop can be considered constant over the range of dynamic interfacial tensions tested.

  1. Transitions of tethered chain molecules under tension.

    PubMed

    Luettmer-Strathmann, Jutta; Binder, Kurt

    2014-09-21

    An applied tension force changes the equilibrium conformations of a polymer chain tethered to a planar substrate and thus affects the adsorption transition as well as the coil-globule and crystallization transitions. Conversely, solvent quality and surface attraction are reflected in equilibrium force-extension curves that can be measured in experiments. To investigate these effects theoretically, we study tethered chains under tension with Wang-Landau simulations of a bond-fluctuation lattice model. Applying our model to pulling experiments on biological molecules we obtain a good description of experimental data in the intermediate force range, where universal features dominate and finite size effects are small. For tethered chains in poor solvent, we observe the predicted two-phase coexistence at transitions from the globule to stretched conformations and also discover direct transitions from crystalline to stretched conformations. A phase portrait for finite chains constructed by evaluating the density of states for a broad range of solvent conditions and tensions shows how increasing tension leads to a disappearance of the globular phase. For chains in good solvents tethered to hard and attractive surfaces we find the predicted scaling with the chain length in the low-force regime and show that our results are well described by an analytical, independent-bond approximation for the bond-fluctuation model for the highest tensions. Finally, for a hard or slightly attractive surface the stretching of a tethered chain is a conformational change that does not correspond to a phase transition. However, when the surface attraction is sufficient to adsorb a chain it will undergo a desorption transition at a critical value of the applied force. Our results for force-induced desorption show the transition to be discontinuous with partially desorbed conformations in the coexistence region.

  2. Actomyosin tension as a determinant of metastatic cancer mechanical tropism

    NASA Astrophysics Data System (ADS)

    McGrail, Daniel J.; Kieu, Quang Minh N.; Iandoli, Jason A.; Dawson, Michelle R.

    2015-04-01

    Despite major advances in the characterization of molecular regulators of cancer growth and metastasis, patient survival rates have largely stagnated. Recent studies have shown that mechanical cues from the extracellular matrix can drive the transition to a malignant phenotype. Moreover, it is also known that the metastatic process, which results in over 90% of cancer-related deaths, is governed by intracellular mechanical forces. To better understand these processes, we identified metastatic tumor cells originating from different locations which undergo inverse responses to altered matrix elasticity: MDA-MB-231 breast cancer cells that prefer rigid matrices and SKOV-3 ovarian cancer cells that prefer compliant matrices as characterized by parameters such as tumor cell proliferation, chemoresistance, and migration. Transcriptomic analysis revealed higher expression of genes associated with cytoskeletal tension and contractility in cells that prefer stiff environments, both when comparing MDA-MB-231 to SKOV-3 cells as well as when comparing bone-metastatic to lung-metastatic MDA-MB-231 subclones. Using small molecule inhibitors, we found that blocking the activity of these pathways mitigated rigidity-dependent behavior in both cell lines. Probing the physical forces exerted by cells on the underlying substrates revealed that though force magnitude may not directly correlate with functional outcomes, other parameters such as force polarization do correlate directly with cell motility. Finally, this biophysical analysis demonstrates that intrinsic levels of cell contractility determine the matrix rigidity for maximal cell function, possibly influencing tissue sites for metastatic cancer cell engraftment during dissemination. By increasing our understanding of the physical interactions of cancer cells with their microenvironment, these studies may help develop novel therapeutic strategies.

  3. Actomyosin tension as a determinant of metastatic cancer mechanical tropism.

    PubMed

    McGrail, Daniel J; Kieu, Quang Minh N; Iandoli, Jason A; Dawson, Michelle R

    2015-02-23

    Despite major advances in the characterization of molecular regulators of cancer growth and metastasis, patient survival rates have largely stagnated. Recent studies have shown that mechanical cues from the extracellular matrix can drive the transition to a malignant phenotype. Moreover, it is also known that the metastatic process, which results in over 90% of cancer-related deaths, is governed by intracellular mechanical forces. To better understand these processes, we identified metastatic tumor cells originating from different locations which undergo inverse responses to altered matrix elasticity: MDA-MB-231 breast cancer cells that prefer rigid matrices and SKOV-3 ovarian cancer cells that prefer compliant matrices as characterized by parameters such as tumor cell proliferation, chemoresistance, and migration. Transcriptomic analysis revealed higher expression of genes associated with cytoskeletal tension and contractility in cells that prefer stiff environments, both when comparing MDA-MB-231 to SKOV-3 cells as well as when comparing bone-metastatic to lung-metastatic MDA-MB-231 subclones. Using small molecule inhibitors, we found that blocking the activity of these pathways mitigated rigidity-dependent behavior in both cell lines. Probing the physical forces exerted by cells on the underlying substrates revealed that though force magnitude may not directly correlate with functional outcomes, other parameters such as force polarization do correlate directly with cell motility. Finally, this biophysical analysis demonstrates that intrinsic levels of cell contractility determine the matrix rigidity for maximal cell function, possibly influencing tissue sites for metastatic cancer cell engraftment during dissemination. By increasing our understanding of the physical interactions of cancer cells with their microenvironment, these studies may help develop novel therapeutic strategies.

  4. Mechanisms of spontaneous activity in developing spinal networks.

    PubMed

    O'Donovan, M J; Chub, N; Wenner, P

    1998-10-01

    Developing networks of the chick spinal cord become spontaneously active early in development and remain so until hatching. Experiments using an isolated preparation of the spinal cord have begun to reveal the mechanisms responsible for this activity. Whole-cell and optical recordings have shown that spinal neurons receive a rhythmic, depolarizing synaptic drive and experience rhythmic elevations of intracellular calcium during spontaneous episodes. Activity is expressed throughout the neuraxis and can be produced by different parts of the cord and by the isolated brain stem, suggesting that it does not depend upon the details of network architecture. Two factors appear to be particularly important for the production of endogenous activity. The first is the predominantly excitatory nature of developing synaptic connections, and the second is the presence of prolonged activity-dependent depression of network excitability. The interaction between high excitability and depression results in an equilibrium in which episodes are expressed periodically by the network. The mechanism of the rhythmic bursting within an episode is not understood, but it may be due to a "fast" form of network depression. Spontaneous embryonic activity has been shown to play a role in neuron and muscle development, but is probably not involved in the initial formation of connections between spinal neurons. It may be important in refining the initial connections, but this possibility remains to be explored.

  5. A Multi Wavelength Study of Active Region Development

    NASA Astrophysics Data System (ADS)

    Lara, A.; Gopalswamy, N.; Kundu, M. R.; Perez-Enriquez, R.; Koshiishi, H.; Enome, S.

    1996-05-01

    We report on a study of the evolution of several active regions during 1993 April 17-28 using data obtained at multiple wavelengths that probe various heights of the active region corona. We use simultaneous microwave (1.5 and 17 GHz) and Soft X-ray images obtained by the Very Large Array (VLA), the Nobeyama Radio Heliograph (NRH) and the Soft X-ray Telescope (SXT) on board the Yohkoh spacecraft. We also use photospheric magnetograms from Kitt Peak National Observatory to study the development of Solar Active Regions. We have followed the development of various observed parameters such as brightness temperature and polarization using radio images. The X-ray data were used to track the development of density and temperature of active regions. Using the fact that the quiet active region radiation is thermal and adopting proper emission mechanism at each frequency domain, we construct a consistent picture for the three dimensional structure of the active regions. Particular attention has been paid to the mode coupling observed at 17 GHz while the active regions crossed the solar disk.

  6. Mechano-adaptive sensory mechanism of α-catenin under tension

    NASA Astrophysics Data System (ADS)

    Maki, Koichiro; Han, Sung-Woong; Hirano, Yoshinori; Yonemura, Shigenobu; Hakoshima, Toshio; Adachi, Taiji

    2016-04-01

    The contractile forces in individual cells drive the tissue processes, such as morphogenesis and wound healing, and maintain tissue integrity. In these processes, α-catenin molecule acts as a tension sensor at cadherin-based adherens junctions (AJs), accelerating the positive feedback of intercellular tension. Under tension, α-catenin is activated to recruit vinculin, which recruits actin filaments to AJs. In this study, we revealed how α-catenin retains its activated state while avoiding unfolding under tension. Using single-molecule force spectroscopy employing atomic force microscopy (AFM), we found that mechanically activated α-catenin fragment had higher mechanical stability than a non-activated fragment. The results of our experiments using mutated and segmented fragments showed that the key intramolecular interactions acted as a conformational switch. We also found that the conformation of α-catenin was reinforced by vinculin binding. We demonstrate that α-catenin adaptively changes its conformation under tension to a stable intermediate state, binds to vinculin, and finally settles into a more stable state reinforced by vinculin binding. Our data suggest that the plastic characteristics of α-catenin, revealed in response to both mechanical and biochemical cues, enable the functional-structural dynamics at the cellular and tissue levels.

  7. Mechano-adaptive sensory mechanism of α-catenin under tension

    PubMed Central

    Maki, Koichiro; Han, Sung-Woong; Hirano, Yoshinori; Yonemura, Shigenobu; Hakoshima, Toshio; Adachi, Taiji

    2016-01-01

    The contractile forces in individual cells drive the tissue processes, such as morphogenesis and wound healing, and maintain tissue integrity. In these processes, α-catenin molecule acts as a tension sensor at cadherin-based adherens junctions (AJs), accelerating the positive feedback of intercellular tension. Under tension, α-catenin is activated to recruit vinculin, which recruits actin filaments to AJs. In this study, we revealed how α-catenin retains its activated state while avoiding unfolding under tension. Using single-molecule force spectroscopy employing atomic force microscopy (AFM), we found that mechanically activated α-catenin fragment had higher mechanical stability than a non-activated fragment. The results of our experiments using mutated and segmented fragments showed that the key intramolecular interactions acted as a conformational switch. We also found that the conformation of α-catenin was reinforced by vinculin binding. We demonstrate that α-catenin adaptively changes its conformation under tension to a stable intermediate state, binds to vinculin, and finally settles into a more stable state reinforced by vinculin binding. Our data suggest that the plastic characteristics of α-catenin, revealed in response to both mechanical and biochemical cues, enable the functional-structural dynamics at the cellular and tissue levels. PMID:27109499

  8. Massively augmented hippocampal dentate granule cell activation accompanies epilepsy development.

    PubMed

    Dengler, Christopher G; Yue, Cuiyong; Takano, Hajime; Coulter, Douglas A

    2017-02-20

    In a mouse model of temporal lobe epilepsy, multicellular calcium imaging revealed that disease emergence was accompanied by massive amplification in the normally sparse, afferent stimulation-induced activation of hippocampal dentate granule cells. Patch recordings demonstrated reductions in local inhibitory function within the dentate gyrus at time points where sparse activation was compromised. Mimicking changes in inhibitory synaptic function and transmembrane chloride regulation was sufficient to elicit the dentate gyrus circuit collapse evident during epilepsy development. Pharmacological blockade of outward chloride transport had no effect during epilepsy development, and significantly increased granule cell activation in both control and chronically epileptic animals. This apparent occlusion effect implicates reduction in chloride extrusion as a mechanism contributing to granule cell hyperactivation specifically during early epilepsy development. Glutamine plays a significant role in local synthesis of GABA in synapses. In epileptic mice, sparse granule cell activation could be restored by glutamine application, implicating compromised GABA synthesis. Glutamine had no effect on granule cell activation earlier, during epilepsy development. We conclude that compromised feedforward inhibition within the local circuit generates the massive dentate gyrus circuit hyperactivation evident in animals during and following epilepsy development. However, the mechanisms underlying this disinhibition diverge significantly as epilepsy progresses.

  9. Massively augmented hippocampal dentate granule cell activation accompanies epilepsy development

    PubMed Central

    Dengler, Christopher G.; Yue, Cuiyong; Takano, Hajime; Coulter, Douglas A.

    2017-01-01

    In a mouse model of temporal lobe epilepsy, multicellular calcium imaging revealed that disease emergence was accompanied by massive amplification in the normally sparse, afferent stimulation-induced activation of hippocampal dentate granule cells. Patch recordings demonstrated reductions in local inhibitory function within the dentate gyrus at time points where sparse activation was compromised. Mimicking changes in inhibitory synaptic function and transmembrane chloride regulation was sufficient to elicit the dentate gyrus circuit collapse evident during epilepsy development. Pharmacological blockade of outward chloride transport had no effect during epilepsy development, and significantly increased granule cell activation in both control and chronically epileptic animals. This apparent occlusion effect implicates reduction in chloride extrusion as a mechanism contributing to granule cell hyperactivation specifically during early epilepsy development. Glutamine plays a significant role in local synthesis of GABA in synapses. In epileptic mice, sparse granule cell activation could be restored by glutamine application, implicating compromised GABA synthesis. Glutamine had no effect on granule cell activation earlier, during epilepsy development. We conclude that compromised feedforward inhibition within the local circuit generates the massive dentate gyrus circuit hyperactivation evident in animals during and following epilepsy development. However, the mechanisms underlying this disinhibition diverge significantly as epilepsy progresses. PMID:28218241

  10. Measuring and Modeling the Surface Tensions of Organic Aqueous Solutions With Atmospheric Significance

    NASA Astrophysics Data System (ADS)

    Aumann, E.; Tabazadeh, A.

    2008-12-01

    Organic compounds account for a substantial fraction of dry submicron atmospheric aerosol mass. Additionally, single particle composition data suggest that individual aerosols are often mixtures of organic and inorganic components. This study measured the surface tensions of atmospherically relevant pure and mixed organic / inorganic aqueous solutions. Measurements were performed using the Wilhelmy plate method at 25°C and 5°C. Small water-soluble organic compounds previously identified in aerosols (i.e. sugars, dicarboxylic acids) were found to alter the surface tension of water to a limited extent. Humic and fulvic acids were used as analog species for the unidentifiable humic-like substances (HULIS) found in atmospheric particles. Natural humic substances were considerably more effective at reducing the surface tension of water than small water-soluble species. However, humic matter reduced the surface tension of water to a lesser degree than measurements reported for atmospheric HULIS. The addition of inorganic species was found to significantly affect the surface activity of natural humic materials. Surface tension data were fit to the Szyszkowski equation to extract Langmuir adsorption parameters (maximum surface excess, Γmax, and the adsorption constant, β) for the aqueous systems. Adsorption parameters were used to model the surface tensions of multi-component solutions.

  11. Changes in droplet surface tension affect the observed hygroscopicity of photochemically aged biomass burning aerosol.

    PubMed

    Giordano, Michael R; Short, Daniel Z; Hosseini, Seyedehsan; Lichtenberg, William; Asa-Awuku, Akua A

    2013-10-01

    This study examines the hygroscopic and surface tension properties as a function of photochemical aging of the aerosol emissions from biomass burning. Experiments were conducted in a chamber setting at the UC-Riverside Center for Environmental Research and Technology (CE-CERT) Atmospheric Processes Lab using two biomass fuel sources, manzanita and chamise. Cloud condensation nuclei (CCN) measurements and off-line filter sample analysis were conducted. The water-soluble organic carbon content and surface tension of the extracted filter samples were measured. Surface tension information was then examined with Köhler theory analysis to calculate the hygroscopicity parameter, κ. Laboratory measurement of biomass burning smoke from two chaparral fuels is shown to depress the surface tension of water by 30% or more at organic matter concentrations relevant at droplet activation. Accounting for surface tension depression can lower the calculated κ by a factor of 2. This work provides evidence for surface tension depression in an important aerosol system and may provide closure for differing sub- and supersaturated κ measurements.

  12. Dynamic simulation and tension compensation research on subsea umbilical cable laying system

    NASA Astrophysics Data System (ADS)

    Bi, Guojun; Zhu, Shaohua; Liu, Jun; Fang, Xiaoming; Wang, Liquan

    2013-12-01

    For studying the dynamic performance of subsea umbilical cable laying system and achieving the goal of cable tension and laying speed control, the rigid finite element method is used to discrete and transform the system into a rigid-flexible coupling multi-body system which consists of rigid elements and spring-damping elements. The mathematical model of subsea umbilical cable laying system kinematic chain is presented with the second order Lagrange equation in the joint coordinate system, and dynamic modeling and simulation is performed with ADAMS. The dynamic analysis is conducted assuming the following three statuses: ideal laying, practical laying under wave disturbance, and practical laying with tension compensation. Results show that motion disturbances of the laying budge under sea waves, especially with heaving and pitching, will cause relatively serious fluctuations in cable tension and laying speed. Tension compensation, i.e., active back tension torque control can restrict continuous tension increasing or decreasing effectively and rapidly, thus avoiding cable breach or buckling.

  13. Development of magnetostrictive active members for control of space structures

    NASA Technical Reports Server (NTRS)

    Johnson, Bruce G.; Avakian, Kevin M.; Fenn, Ralph C.; Gaffney, Monique S.; Gerver, Michael J.; Hawkey, Timothy J.; Boudreau, Donald J.

    1992-01-01

    The goal of this Phase 2 Small Business Innovative Research (SBIR) project was to determine the technical feasibility of developing magnetostrictive active members for use as truss elements in space structures. Active members control elastic vibrations of truss-based space structures and integrate the functions of truss structure element, actively controlled actuator, and sensor. The active members must control structural motion to the sub-micron level and, for many proposed space applications, work at cryogenic temperatures. Under this program both room temperature and cryogenic temperature magnetostrictive active members were designed, fabricated, and tested. The results of these performance tests indicated that room temperature magnetostrictive actuators feature higher strain, stiffness, and force capability with lower amplifier requirements than similarly sized piezoelectric or electrostrictive active members, at the cost of higher mass. Two different cryogenic temperature magnetostrictive materials were tested at liquid nitrogen temperatures, both with larger strain capability than the room temperature magnetostrictive materials. The cryogenic active member development included the design and fabrication of a cryostat that allows operation of the cryogenic active member in a space structure testbed.

  14. Developing a national physical activity plan: the Kuwait example.

    PubMed

    Ramadan, Jasem; Vuori, Ilkka; Lankenau, Becky; Schmid, Tom; Pratt, Michael

    2010-06-01

    A rapid increase in economic well-being and urbanization in Kuwait have been accompanied by profound changes in lifestyle, including low levels of physical activity in all population groups. These changes have contributed to a high prevalence of overweight and obesity and to the escalation of the non-communicable disease rates, particularly coronary heart disease, stroke, hypertension and diabetes. The evolution of physical activity promotion, internationally, and a series of related meetings in Kuwait and neighboring countries, have started to generate an awareness among health authorities of the importance of physical activity in health promotion and disease prevention. A National Physical Activity Committee has been formed to design and implement a National Physical Activity Plan, which could also serve as a model for other countries. The authors describe the background and principles behind the development of the National Plan, summarize a template based upon the Kuwait experience and share the lessons learned from these efforts.

  15. Vehicle Engineering Development Activities at the Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    Fisher, Mark F.; Champion, Robert H., Jr.

    1999-01-01

    New initiatives in the Space Transportation Directorate at the Marshall Space Flight Center include an emphasis on Vehicle Engineering to enhance the strong commitment to the Directorate's projects in the development of flight hardware and flight demonstrators for the advancement of space transportation technology. This emphasis can be seen in the activities of a newly formed organization in the Transportation Directorate, The Vehicle Subsystems Engineering Group. The functions and type of activities that this group works on are described. The current projects of this group are outlined including a brief description of the status and type of work that the group is performing. A summary section is included to describe future activities.

  16. Development of a new biosensor for determination of catalase activity.

    PubMed

    Teke, Mustafa

    2014-01-01

    Catalase is one of the major antioxidant enzymes that catalyzes the hydrolysis of H2O2. The aim of this study was to suggest a new method for the assay of catalase activity. For this purpose, an amperometric biosensor based on glucose oxidase for determination of catalase activity was developed. Immobilization of glucose oxidase was made by a cross-linking method with glutaraldehyde on a Clark-type electrode (dissolved oxygen probe). Optimization and characterization properties of the biosensor were studied and determination of catalase activity in defined conditions was investigated in artificial serum solution. The results were compared with a reference method.

  17. The Role of Regular Home Practice in the Relaxation Treatment of Tension Headache.

    ERIC Educational Resources Information Center

    Blanchard, Edward B.; And Others

    1991-01-01

    Gave 27 tension headache sufferers progressive muscle relaxation (PMR) training, with 14 of those subjects also receiving home practice and application instructions. Compared to third group of sufferers (n=6) who merely monitored headache activity, both treated groups showed significant reduction in headache activity. Treatment groups did not…

  18. Board Tensions and Activist Trustees: Current Domestic Cases and Implications for the Enrollment Manager

    ERIC Educational Resources Information Center

    Levine, Jeffrey P.

    2016-01-01

    Utilizing five recent highly-visible case studies of campus tensions between boards of trustees and trustee activism, the researcher examined each case, the history of trustees, the shift in trustee activism, what happened and what can be learned from each case, institutional context, the role of the trustee, and several responses. The researcher…

  19. Surface tension of the two center Lennard-Jones plus point dipole fluid.

    PubMed

    Werth, Stephan; Horsch, Martin; Hasse, Hans

    2016-02-07

    Molecular dynamics simulations are used for systematically studying the surface tension of the two center Lennard-Jones plus point dipole (2CLJD) model fluid. In a dimensionless representation, this model fluid has two parameters describing the elongation and the dipole moment. These parameters were varied in the entire range relevant for describing real fluids resulting in a grid of 38 individual models. For each model, the surface tension was determined at temperatures between 60% and 90% of the critical temperature. For completeness, the vapor pressure and the saturated densities were also determined. The latter results agree well with the literature data, whereas for the surface tension, only few data were previously available. From the present results, an empirical correlation for the surface tension of the 2CLJD model as a function of the model parameters is developed. The correlation is used to predict the surface tension of 46 2CLJD molecular models from the literature, which were adjusted to bulk properties, but not to interfacial properties. The results are compared to the experimental data. The molecular models overestimate the surface tension, and deviations between the predictions and experimental data are below 12% on average.

  20. Comparing contact angle measurements and surface tension assessments of solid surfaces.

    PubMed

    Cwikel, Dory; Zhao, Qi; Liu, Chen; Su, Xueju; Marmur, Abraham

    2010-10-05

    Four types of contact angles (receding, most stable, advancing, and "static") were measured by two independent laboratories for a large number of solid surfaces, spanning a large range of surface tensions. It is shown that the most stable contact angle, which is theoretically required for calculating the Young contact angle, is a practical, useful tool for wettability characterization of solid surfaces. In addition, it is shown that the experimentally measured most stable contact angle may not always be approximated by an average angle calculated from the advancing and receding contact angles. The "static" CA is shown in many cases to be very different from the most stable one. The measured contact angles were used for calculating the surface tensions of the solid samples by five methods. Meaningful differences exist among the surface tensions calculated using four previously known methods (Owens-Wendt, Wu, acid-base, and equation of state). A recently developed, Gibbsian-based correlation between interfacial tensions and individual surface tensions was used to calculate the surface tensions of the solid surfaces from the most stable contact angle of water. This calculation yielded in most cases higher values than calculated with the other four methods. On the basis of some low surface energy samples, the higher values appear to be justified.

  1. Post-tensioning and splicing of precast/prestressed bridge beams to extend spans

    NASA Astrophysics Data System (ADS)

    Collett, Brandon S.; Saliba, Joseph E.

    2002-06-01

    This paper explores the status and techniques of post-tensioning and splicing precast concrete I-beams in bridge applications. It will look at the current practices that have been used in the United States and comment on the advantages of these techniques. Representative projects are presented to demonstrate the application and success of specific methods used. To demonstrate the benefits of using post-tensioning and splicing to extend spans, multiple analysis of simple span post-tensioned I-beams were performed varying such characteristics as beam spacing, beam sections, beam depth and concrete strength. Tables were then developed to compare the maximum span length of a prestressed I-beam versus a one segment or a spliced three segment post-tensioned I-beam. The lateral stability of the beam during fabrication, transportation and erection is also examined and discussed. These tables are intended to aid designers and owners in preliminary project studies to determine if post-tensioning can be beneficial to their situation. AASHTO Standard Specifications(2) will be used as basic guidelines and specifications. In many cases, post-tensioning was found to extend the maximum span length of a typical 72-inch precast I-beam more than 40 feet over conventional prestress.

  2. A New Skin Tensiometer Device: Computational Analyses To Understand Biodynamic Excisional Skin Tension Lines.

    PubMed

    Paul, Sharad P; Matulich, Justin; Charlton, Nick

    2016-07-25

    One of the problems in planning cutaneous surgery is that human skin is anisotropic, or directionally dependent. Indeed, skin tension varies between individuals and at different body sites. Many a surgeon has tried to design different devices to measure skin tension to help plan excisional surgery, or to understand wound healing. However, many of the devices have been beset with problems due to many confounding variables - differences in technical ability, material (sutures) used and variability between different users. We describe the development of a new skin tensiometer that overcomes many historical technical issues. A new skin tension measuring device is presented here. It was designed to be less user-dependent, more reliable and usable on different bodily sites. The design and computational optimizations are discussed. Our skin tensiometer has helped understand the differences between incisional and excisional skin lines. Langer, who pioneered the concept of skin tension lines, created incisional lines that differ from lines caused by forces that need to be overcome when large wounds are closed surgically (excisional tension). The use of this innovative device has led to understanding of skin biomechanics and best excisional skin tension (BEST) lines.

  3. A New Skin Tensiometer Device: Computational Analyses To Understand Biodynamic Excisional Skin Tension Lines

    PubMed Central

    Paul, Sharad P.; Matulich, Justin; Charlton, Nick

    2016-01-01

    One of the problems in planning cutaneous surgery is that human skin is anisotropic, or directionally dependent. Indeed, skin tension varies between individuals and at different body sites. Many a surgeon has tried to design different devices to measure skin tension to help plan excisional surgery, or to understand wound healing. However, many of the devices have been beset with problems due to many confounding variables - differences in technical ability, material (sutures) used and variability between different users. We describe the development of a new skin tensiometer that overcomes many historical technical issues. A new skin tension measuring device is presented here. It was designed to be less user-dependent, more reliable and usable on different bodily sites. The design and computational optimizations are discussed. Our skin tensiometer has helped understand the differences between incisional and excisional skin lines. Langer, who pioneered the concept of skin tension lines, created incisional lines that differ from lines caused by forces that need to be overcome when large wounds are closed surgically (excisional tension). The use of this innovative device has led to understanding of skin biomechanics and best excisional skin tension (BEST) lines. PMID:27453542

  4. School and community relations in North America: Creative tensions

    NASA Astrophysics Data System (ADS)

    Loughran, E.; Reed, H. B.

    1980-09-01

    School and community relations in North America reflect creative tensions between the conserving forces of schooling and the changing forces of community. During crisis periods community development needs may modify the school's focus on individual learner growth, but generally schools use the community to extend and enrich the traditional modes. School and community interactions are chiefly characterized by such settings as community schools, community education, adult education, home and school (PTA) associations, work-study programs, curriculum-community resource programs. Recent social forces are creating heightened tensions: cultural pluralism, reduced resources, Third World influences, international conflicts, personal alienation, population concerns, energy problems, community power issues. These forces are gradually shifting school and community concepts towards ones of education and community. Education goes well beyond schooling, including all agencies having an organized influence on community development: libraries, voluntary groups, unions, business, human service agencies, government units, as well as schools. This shift requires research to develop nonformal concepts and practices, along with formal pedagogy, to increase the positive impacts of educational networks on community, as well as individual, development. These new directions have not yet significantly modified the traditional meaning of school and community relations.

  5. Flow rate analysis of a surface tension driven passive micropump.

    PubMed

    Berthier, Erwin; Beebe, David J

    2007-11-01

    A microfluidic passive pumping method relying on surface tension properties is investigated and a physical model is developed. When a small inlet drop is placed on the entrance of a microfluidic channel it creates more pressure than a large output drop at the channel exit, causing fluid flow. The behavior of the input drop occurs in two characteristic phases. An analytical solution is proposed and verified by experimental results. We find that during the first phase the flow rate is stable and that this phase can be prolonged by refilling the inlet drop to produce continuous flow in the microchannel.

  6. Differentiating Leber Hereditary Optic Neuropathy from Normal-Tension Glaucoma.

    PubMed

    Souto, Fernanda Maria Silveira; de Vasconcellos, José Paulo Cabral; de Melo, Mônica Barbosa; Sartorato, Edi Lúcia; Moura, Frederico Castelo

    2017-04-01

    Glaucoma is a neurodegenerative disorder characterized by thinning of neuroretinal rim, enlarged cup-to-disc ratio (CDR) and visual field damage. Although raised intraocular pressure is main risk factor for development of glaucoma, it can occur with consistently normal measurements in the intraocular pressure as normal tension glaucoma (NTG). Enlargement of CDR is a classical sign of glaucoma, but it can also result from non-glaucomatous optic neuropathies such as Leber hereditary optic neuropathy (LHON). We describe a case of LHON with increased CDR, discuss its differential diagnosis with NTG and highlight the reasons for misdiagnoses between these two entities.

  7. Tension Headaches: A Challenge to the Family Physician

    PubMed Central

    Cohen, May

    1978-01-01

    Tension headache is a frequently encountered symptom. The skills of the family physician make him or her ideally suited to assess and manage the patient with this problem. Diagnosis depends on a thorough understanding of the nature and ‘life-history’ of the headache as well as knowledge of the patient as an individual and as part of his or her family and social environment. Management requires a holistic ongoing approach, employing a judicious combination of medication and physical therapy. Above all, the physician must help the patient develop different ways of dealing with anxiety and conflict. PMID:21301541

  8. Replicating an intervention: the tension between fidelity and adaptation.

    PubMed

    Morrison, Diane M; Hoppe, Marilyn J; Gillmore, Mary Rogers; Kluver, Carisa; Higa, Darrel; Wells, Elizabeth A

    2009-04-01

    Increased awareness of the importance of tailoring interventions to participants' cultures has focused attention on the limited generalizability of a single test of an intervention to determine efficacy. Adaptation is often necessary to replicate interventions across cultures. This produces a tension between fidelity to the original intervention and adaptations necessary to make the intervention relevant to the culture and circumstances of participants. This article discusses issues that arise during the course of replication, with illustrations from a replication to test the efficacy of an HIV prevention intervention for youth, using a randomized controlled design. Analysis of the issues raised leads us to suggest that a "science of replication" needs to be developed.

  9. Scaling for interfacial tensions near critical endpoints.

    PubMed

    Zinn, Shun-Yong; Fisher, Michael E

    2005-01-01

    Parametric scaling representations are obtained and studied for the asymptotic behavior of interfacial tensions in the full neighborhood of a fluid (or Ising-type) critical endpoint, i.e., as a function both of temperature and of density/order parameter or chemical potential/ordering field. Accurate nonclassical critical exponents and reliable estimates for the universal amplitude ratios are included naturally on the basis of the "extended de Gennes-Fisher" local-functional theory. Serious defects in previous scaling treatments are rectified and complete wetting behavior is represented; however, quantitatively small, but unphysical residual nonanalyticities on the wetting side of the critical isotherm are smoothed out "manually." Comparisons with the limited available observations are presented elsewhere but the theory invites new, searching experiments and simulations, e.g., for the vapor-liquid interfacial tension on the two sides of the critical endpoint isotherm for which an amplitude ratio -3.25+/-0.05 is predicted.

  10. DNA loops generate intracentromere tension in mitosis

    PubMed Central

    Lawrimore, Josh; Vasquez, Paula A.; Falvo, Michael R.; Taylor, Russell M.; Vicci, Leandra; Yeh, Elaine; Forest, M. Gregory

    2015-01-01

    The centromere is the DNA locus that dictates kinetochore formation and is visibly apparent as heterochromatin that bridges sister kinetochores in metaphase. Sister centromeres are compacted and held together by cohesin, condensin, and topoisomerase-mediated entanglements until all sister chromosomes bi-orient along the spindle apparatus. The establishment of tension between sister chromatids is essential for quenching a checkpoint kinase signal generated from kinetochores lacking microtubule attachment or tension. How the centromere chromatin spring is organized and functions as a tensiometer is largely unexplored. We have discovered that centromere chromatin loops generate an extensional/poleward force sufficient to release nucleosomes proximal to the spindle axis. This study describes how the physical consequences of DNA looping directly underlie the biological mechanism for sister centromere separation and the spring-like properties of the centromere in mitosis. PMID:26283798

  11. Film tension of liquid nano-film from molecular modeling

    NASA Astrophysics Data System (ADS)

    Peng, Tiefeng; Yang, Siyuan; Xiang, Fan; Liang, Yunpei; Li, Qibin; Gao, Xuechao; Liu, Sanjun

    2017-02-01

    Due to its geometry simplicity, the forces of thin liquid film are widely investigated and equivalently employed to explore the phys-chemical properties and mechanical stability of many other surfaces or colloid ensembles. The surface tension of bulk liquid (σ∞) and film tension (γ) are the most important parameters. Considering the insufficiency of detailed interpretation of film tension under micro-scale circumstances, a method for film tension was proposed based on numerical modeling. Assuming surface tension at different slab thicknesses being identical to the surface tension of film, the surface tension and disjoining pressure were subsequently used to evaluate the film tension based on the derivation of film thermodynamics, and a decreasing tendency was discovered for low temperature regions. The influence of saline concentration on nano-films was also investigated, and the comparison of film tensions suggested that higher concentration yielded larger film tension, with stronger decreasing intensity as a function of film thickness. Meanwhile, at thick film range (15-20 nm), film tension of higher concentration film continued to decrease as thickness increase, however it arrived to constant value for that of lower concentration. Finally, it was found that the film tension was almost independent on the film curvature, but varied with the thickness. The approach is applicable to symmetric emulsion films containing surfactants and bi-layer lipid films.

  12. Tensions of Teaching Media Literacy in Teacher Education

    ERIC Educational Resources Information Center

    Ngomba-Westbrook, Nalova Elaine

    2013-01-01

    This study investigates the tensions a teacher educator faces in facilitating a media literacy teacher education course at the university level. Teaching tensions are conceptualized as a three-tier framework. At the first level, tensions may arise in the selection and application of pedagogies associated with critical and new/21st century…

  13. A microprocessor based portable bolt tension monitor

    NASA Technical Reports Server (NTRS)

    Perey, D. F.

    1991-01-01

    A bolt tension monitor (BTM) which uses ultrasonics and a pulsed phase locked loop circuit to measure load-induced acoustic phase shifts which are independent of friction is described. The BTM makes it possible to measure the load in a bolt that was tightened at some time in the past. This capability to recertify a load after-the-fact will help to insure the integrity of a bolted joint.

  14. Increasing Pupil Physical Activity: A Comprehensive Professional Development Effort

    ERIC Educational Resources Information Center

    Kulinna, Pamela Hodges

    2012-01-01

    Study aim: To determine if pupil physical activity and Body Mass Index classifications maintained or improved after a one-year professional development program involving both classroom and physical education teachers. Guskey's model of teacher change guided this study. Material and methods: Indigenous children from ten schools (N = 320) in grades…

  15. Exploring Key Sustainable Development Themes through Learning Activities

    ERIC Educational Resources Information Center

    Cruickshank, Heather; Fenner, Richard

    2012-01-01

    Purpose: The purpose of the paper is to examine how a number of key themes are introduced in the Master's programme in Engineering for Sustainable Development, at Cambridge University, through student-centred activities. These themes include dealing with complexity, uncertainty, change, other disciplines, people, environmental limits, whole life…

  16. 48 CFR 927.408 - Cosponsored research and development activities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Cosponsored research and development activities. 927.408 Section 927.408 Federal Acquisition Regulations System DEPARTMENT OF ENERGY GENERAL CONTRACTING REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS Technical Data and Copyrights...

  17. 48 CFR 927.408 - Cosponsored research and development activities.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Cosponsored research and development activities. 927.408 Section 927.408 Federal Acquisition Regulations System DEPARTMENT OF ENERGY GENERAL CONTRACTING REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS Technical Data and Copyrights...

  18. 48 CFR 27.408 - Cosponsored research and development activities.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false Cosponsored research and development activities. 27.408 Section 27.408 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION GENERAL CONTRACTING REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS Rights in Data and Copyrights...

  19. Measuring Active Citizenship through the Development of a Composite Indicator

    ERIC Educational Resources Information Center

    Hoskins, Bryony L.; Mascherini, Massimiliano

    2009-01-01

    This article defines Active Citizenship within a European context as a broad range of value based participation. It develops a framework for measuring this phenomenon which combines the four dimensions of Protest and Social Change, Community Life, Representative Democracy and Democratic values. The European Social Survey 2002 is used to populate…

  20. 250+ Activities and Ideas for Developing Literacy Skills.

    ERIC Educational Resources Information Center

    Jay, Hilda L.; Jay, M. Ellen

    Designed for use at school or at home, this book focuses on the development of seven types of literacy: linguistic, visual, mathematical, scientific, geographic, economic, and computer. The book's suggested activities are each introduced with a detailed discussion of the necessary prerequisite skills, the concepts to be mastered, the materials…

  1. CurioCity, Developing an "Active Learning" Game.

    ERIC Educational Resources Information Center

    Ferguson, Lynne

    1999-01-01

    Describes a case study that takes readers through a human-centered design process used in developing an "Active Learning" tool, CurioCity, a game for students in grades 7-10. Attempts to better understand multiculturalism and to bridge formal in-school learning with informal field trip learning. (SC)

  2. Development and Pilot Investigation of Behavioral Activation for Negative Symptoms

    ERIC Educational Resources Information Center

    Mairs, Hilary; Lovell, Karina; Campbell, Malcolm; Keeley, Philip

    2011-01-01

    Negative symptoms cause functional impairment and impede recovery from psychosis, not least, because of limited developments in empirically validated treatments. This article details a pilot evaluation of a behavioral activation (BA) treatment with eight people presenting with psychosis and marked negative symptoms. The rationale for this…

  3. Development of the Arab Heritage Activity Card Sort

    ERIC Educational Resources Information Center

    Hamed, Razan; AlHeresh, Rawan; Dahab, Sana Abu; Collins, Brittany; Fryer, Jasmine; Holm, Margo B.

    2011-01-01

    Participation is an indicator of healthy functioning and well-being, as emphasized by the International Classification of Functioning, Disability, and Health (World Health Organization, 2001). The Activity Card Sort (ACS) is a valid and reliable assessment tool that measures participation. This study describes the process of developing the Arab…

  4. Development of Intellectual Activity in Solving Exponential Inequalities

    ERIC Educational Resources Information Center

    Alpyssov, Akan; Mukanova, Zhazira; Kireyeva, Assel; Sakenov, Janat; Kervenev, Kabylgazy

    2016-01-01

    The article describes the possibilities and the main directions of development of intellectual activity in teaching mathematics in school. The aims and specific features of application of international comparative TIMSS and PISA studies, as well as their results in the field of mathematics education in relation to the pupils in Kazakhstan are…

  5. Developing active noise control systems for noise attenuation in ducts

    NASA Astrophysics Data System (ADS)

    Campos, Rosely V.; Ivo, Rodrigo C.; Medeiros, Eduardo B.

    2002-11-01

    The present work describes some of the research effort on Active Noise Control (ANC) being jointly developed by the Catholic University of Minas Gerais (PUC-MINAS) and the Federal University of Minas Gerais (UFMG). Considerations about the implementation of Digital Signal Processing for noise control in ducts has been presented. The objective is to establish a study on Active Noise Control in ducts combining geometry and acoustic parameters modification together with adaptive digital filtering implementation. Both algorithm and digital signal processing details are also discussed. The main results for a typical application where real attenuation has been obtained are presented and considered according to their use in developing real applications. The authors also believe that the present text should provide an interesting overview for both designers and students concerned about Active Noise Control in ducts. (To be presented in Portuguese.)

  6. An anisotropic constitutive model with biaxial-tension coupling for woven composite reinforcements

    NASA Astrophysics Data System (ADS)

    Yao, Yuan; Huang, Xiaoshuang; Peng, Xiongqi; Gong, Youkun

    2016-10-01

    Based on fiber reinforced continuum mechanics theory, an anisotropic hyperelastic constitutive model with biaxial tension coupling for woven composite reinforcements is developed. Experimental data from literature are used to identify material parameters in the constitutive model for a specific balanced plain woven fabric. The developed model is validated by comparing numerical results with experimental biaxial tension data under different stretch ratios and picture-frame shear data, demonstrating that the developed constitutive model is highly suitable to characterize the highly non-linear and strongly anisotropic mechanical behaviors of woven composite reinforcements under large deformation.

  7. Sexuality, rights and personhood: tensions in a transnational world

    PubMed Central

    2011-01-01

    Background This article discusses what happens when normative ‘global’ discourses of rights and individuated sexual identity confront the messiness of ‘local’ realities. It considers the tensions that emerge when the relationship between sexual and social identities is not obvious and the implications of such tensions for public health and sexual rights activism. These questions are addressed through debates over the naming of male-to-male sexualities and desires in the context of globalization and the growth of a large NGO (non-governmental organization) sector in urban Bangladesh. Methods The material in the paper draws on a research project undertaken in 2008-9 in Dhaka, Bangladesh. A fundamental objective was to produce a contextualized understanding of sexuality in Dhaka city. Methods used included structured interviews, focus group discussions and informal conversations with a range of participants (students, factory workers, public health professionals and sexual minorities). The aim was to generate a conceptual and analytical framework around sexuality and rights rather than to undertake an empirical survey of any one population. Results As descriptors, globalized identity categories such as Men who have Sex with Men (MSM), used by public health providers, the state and donors; and gay/lesbian, invoked by human rights activists and transnational NGOs, are too narrow to capture the fluid and highly context-specific ways in which gender and sexually nonconforming persons understand themselves in Bangladesh. Further, class position mediates to a significant degree the reception, appropriation or rejection of transnational categories such as MSM and Lesbian, Gay, Bisexual, Transgender (LGBT). The tension is reflected in the sometimes fraught relations between service providers to MSM, the people they serve and an emerging group who identify as LGBT. Conclusion A simple politics of recognition will be inadequate to the task of promoting health and human

  8. Masterpiece Me: Children's Activities in Anatomy and Development. Children's Activity Series.

    ERIC Educational Resources Information Center

    Wittman, Sally

    The supplemental teaching resources provided in this book offer a variety of concrete, visual activities designed for the use of classroom and daycare center teachers to help young children feel proud and comfortable about their changing bodies. The lessons help children develop a healthy, age-appropriate foundation in anatomy and development.…

  9. Distinct Biochemical Activities of Eyes absent During Drosophila Eye Development.

    PubMed

    Jin, Meng; Mardon, Graeme

    2016-03-16

    Eyes absent (Eya) is a highly conserved transcriptional coactivator and protein phosphatase that plays vital roles in multiple developmental processes from Drosophila to humans. Eya proteins contain a PST (Proline-Serine-Threonine)-rich transactivation domain, a threonine phosphatase motif (TPM), and a tyrosine protein phosphatase domain. Using a genomic rescue system, we find that the PST domain is essential for Eya activity and Dac expression, and the TPM is required for full Eya function. We also find that the threonine phosphatase activity plays only a minor role during Drosophila eye development and the primary function of the PST and TPM domains is transactivation that can be largely substituted by the heterologous activation domain VP16. Along with our previous results that the tyrosine phosphatase activity of Eya is dispensable for normal Eya function in eye formation, we demonstrate that a primary function of Eya during Drosophila eye development is as a transcriptional coactivator. Moreover, the PST/TPM and the threonine phosphatase activity are not required for in vitro interaction between retinal determination factors. Finally, this work is the first report of an Eya-Ey physical interaction. These findings are particularly important because they highlight the need for an in vivo approach that accurately dissects protein function.

  10. Early development of synchrony in cortical activations in the human

    PubMed Central

    Koolen, N.; Dereymaeker, A.; Räsänen, O.; Jansen, K.; Vervisch, J.; Matic, V.; Naulaers, G.; De Vos, M.; Van Huffel, S.; Vanhatalo, S.

    2016-01-01

    Early intermittent cortical activity is thought to play a crucial role in the growth of neuronal network development, and large scale brain networks are known to provide the basis for higher brain functions. Yet, the early development of the large scale synchrony in cortical activations is unknown. Here, we tested the hypothesis that the early intermittent cortical activations seen in the human scalp EEG show a clear developmental course during the last trimester of pregnancy, the period of intensive growth of cortico-cortical connections. We recorded scalp EEG from altogether 22 premature infants at post-menstrual age between 30 and 44 weeks, and the early cortical synchrony was quantified using recently introduced activation synchrony index (ASI). The developmental correlations of ASI were computed for individual EEG signals as well as anatomically and mathematically defined spatial subgroups. We report two main findings. First, we observed a robust and statistically significant increase in ASI in all cortical areas. Second, there were significant spatial gradients in the synchrony in fronto-occipital and left-to-right directions. These findings provide evidence that early cortical activity is increasingly synchronized across the neocortex. The ASI-based metrics introduced in our work allow direct translational comparison to in vivo animal models, as well as hold promise for implementation as a functional developmental biomarker in future research on human neonates. PMID:26876605

  11. Pumpless Transport of Low Surface Tension Liquids in Surface Tension Confined (STC) Tracks

    NASA Astrophysics Data System (ADS)

    Megaridis, Constantine; Schutzius, Thomas; Elsharkawy, Mohamed; Tiwari, Manish

    2012-11-01

    Surfaces with patterned wettability have potential applications in microfluidics, fog capture, pool boiling, etc. With recent fabrication advancements, surfaces with adjacent superhydrophobic and superhydrophilic regions are feasible at a reasonable cost; with properly designed patterns, one can produce microfluidic paths (a.k.a. surface tension confined or STC tracks) where a liquid is confined and transported by surface tension alone. The surface tension of water is relatively high (72 mN/m), as compared with oils (~25 mN/m) and organic solvents (~20 mN/m). This makes the design of STC channels for oils and organic solvents far more difficult. In this study, open STC tracks for pumpless transport of low-surface tension liquids (acetone, ethanol, and hexadecane) on microfluidic chips are fabricated using a large-area, wet-processing technique. Wettable, wax-based, submillimeter-wide tracks are applied by a fountain-pen procedure on superoleophobic, fluoroacrylic carbon nanofiber (CNF) composite coatings. The fabricated anisotropic wetting patterns confine the low-surface tension liquids onto the flow tracks, driving them with meniscus velocities exceeding 3 cm/s. Scaling arguments and Washburn's equation provide estimates of the liquid velocities measured in these tracks, which also act as rails for directional sliding control of mm-sized water droplets. The present facile patterned wettability approach can be extended to deposit micrometer-wide tracks.

  12. Numerical Tension Adjustment of X-Ray Membrane to Represent Goat Skin Kompang

    NASA Astrophysics Data System (ADS)

    Syiddiq, M.; Siswanto, W. A.

    2017-01-01

    This paper presents a numerical membrane model of traditional musical instrument kompang that will be used to find the parameter of membrane tension of x-ray membrane representing the classical goat-skin membrane of kompang. In this study, the experiment towards the kompang is first conducted in an acoustical anechoic enclosure and in parallel a mathematical model of the kompang membrane is developed to simulate the vibration of the kompang membrane in polar coordinate by implementing Fourier-Bessel wave function. The wave equation in polar direction in mode 0,1 is applied to provide the corresponding natural frequencies of the circular membrane. The value of initial and boundary conditions in the function is determined from experiment to allow the correct development of numerical equation. The numerical mathematical model is coded in SMath for the accurate numerical analysis as well as the plotting tool. Two kompang membrane cases with different membrane materials, i.e. goat skin and x-ray film membranes with fixed radius of 0.1 m are used in the experiment. An alternative of kompang’s membrane made of x-ray film with the appropriate tension setting can be used to represent the sound of traditional goat-skin kompang. The tension setting of the membrane to resemble the goat-skin is 24N. An effective numerical tool has been used to help kompang maker to set the tension of x-ray membrane. In the future application, any traditional kompang with different size can be replaced by another membrane material if the tension is set to the correct tension value. The numerical tool used is useful and handy to calculate the tension of the alternative membrane material.

  13. Development of a complex of activity in the solar corona

    NASA Technical Reports Server (NTRS)

    Howard, R.; Svestka, Z.

    1977-01-01

    Using Skylab observations of soft solar X-rays, the development of a complex of activity in the solar corona during its whole lifetime of seven solar rotations is studied. The basic components of the activity complex were determined to be permanently interconnected through sets of magnetic field lines, which suggests similar connections also below the photosphere. The visibility of individual loops in these connections, however, was greatly variable and typically shorter than one day. Each brightening of a coronal loop in X-rays seems to be related to a variation in the photospheric magnetic field near its footprint.

  14. Polymeric drugs: Advances in the development of pharmacologically active polymers

    PubMed Central

    Li, Jing; Yu, Fei; Chen, Yi; Oupický, David

    2015-01-01

    Synthetic polymers play a critical role in pharmaceutical discovery and development. Current research and applications of pharmaceutical polymers are mainly focused on their functions as excipients and inert carriers of other pharmacologically active agents. This review article surveys recent advances in alternative pharmaceutical use of polymers as pharmacologically active agents known as polymeric drugs. Emphasis is placed on the benefits of polymeric drugs that are associated with their macromolecular character and their ability to explore biologically relevant multivalency processes. We discuss the main therapeutic uses of polymeric drugs as sequestrants, antimicrobials, antivirals, and anticancer and anti-inflammatory agents. PMID:26410809

  15. Nitric oxide mediates local activity-dependent excitatory synapse development.

    PubMed

    Nikonenko, Irina; Nikonenko, Alexander; Mendez, Pablo; Michurina, Tatyana V; Enikolopov, Grigori; Muller, Dominique

    2013-10-29

    Learning related paradigms play an important role in shaping the development and specificity of synaptic networks, notably by regulating mechanisms of spine growth and pruning. The molecular events underlying these synaptic rearrangements remain poorly understood. Here we identify NO signaling as a key mediator of activity-dependent excitatory synapse development. We find that chronic blockade of NO production in vitro and in vivo interferes with the development of hippocampal and cortical excitatory spine synapses. The effect results from a selective loss of activity-mediated spine growth mechanisms and is associated with morphological and functional alterations of remaining synapses. These effects of NO are mediated by a cGMP cascade and can be reproduced or prevented by postsynaptic expression of vasodilator-stimulated phosphoprotein phospho-mimetic or phospho-resistant mutants. In vivo analyses show that absence of NO prevents the increase in excitatory synapse density induced by environmental enrichment and interferes with the formation of local clusters of excitatory synapses. We conclude that NO plays an important role in regulating the development of excitatory synapses by promoting local activity-dependent spine-growth mechanisms.

  16. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    SciTech Connect

    Harold H. Schobert; M. Mercedes Maroto-Valer; Zhe Lu

    2003-09-30

    inferred from their physical and chemical properties. The developed porosity of the activated carbon was a function of the oxygen content, porosity and H/C ratio of the parent unburned carbon feedstock. It was observed that extended activation times and high activation temperatures increased the porosity of the produced activated carbon at the expense of the solid yield. The development of activated carbon from unburned carbon in fly ash has been proven to be a success by this study in terms of the higher surface areas of the resultant activated carbons, which are comparable with commercial activated carbons. However, unburned carbon samples obtained from coal-fired power plants as by-product have high ash content, which is unwanted for the production of activated carbons. Therefore, the separation of unburned carbon from the fly ash is expected to be beneficial for the utilization of unburned carbon to produce activated carbons with low ash content.

  17. Active Reading Experience Questionnaire: Development and Validation of an Instrument for Studying Active Reading Activities

    ERIC Educational Resources Information Center

    Palilonis, Jennifer; Butler, Darrell

    2015-01-01

    The increasing adoption of mobile platforms and digital textbooks in university classrooms continues to have a profound impact on higher education. Advocates believe that providing students digital textbooks with built-in annotation features and interactive study tools will improve learning by facilitating active reading, a task essential to…

  18. Toward a general psychological model of tension and suspense

    PubMed Central

    Lehne, Moritz; Koelsch, Stefan

    2015-01-01

    Tension and suspense are powerful emotional experiences that occur in a wide variety of contexts (e.g., in music, film, literature, and everyday life). The omnipresence of tension and suspense suggests that they build on very basic cognitive and affective mechanisms. However, the psychological underpinnings of tension experiences remain largely unexplained, and tension and suspense are rarely discussed from a general, domain-independent perspective. In this paper, we argue that tension experiences in different contexts (e.g., musical tension or suspense in a movie) build on the same underlying psychological processes. We discuss key components of tension experiences and propose a domain-independent model of tension and suspense. According to this model, tension experiences originate from states of conflict, instability, dissonance, or uncertainty that trigger predictive processes directed at future events of emotional significance. We also discuss possible neural mechanisms underlying tension and suspense. The model provides a theoretical framework that can inform future empirical research on tension phenomena. PMID:25717309

  19. Physical activity and pediatric multiple sclerosis: Developing a research agenda.

    PubMed

    Yeh, E Ann; Kinnett-Hopkins, Dominique; Grover, Stephanie A; Motl, Robert W

    2015-11-01

    Three-quarters of children with multiple sclerosis (MS) experience fatigue or depression, and progressive neurocognitive decline may be seen as early as two years after MS diagnosis. Furthermore, a higher magnetic resonance imaging disease burden is seen in pediatric-onset MS compared with adult-onset MS. To date, limited knowledge exists regarding behavioral methods for managing symptoms and disease progression in pediatric MS. To that end, this paper builds an evidence-based argument for the possible symptomatic and disease-modifying effects of exercise and physical activity in pediatric MS. This will be accomplished through: (a) a review of pediatric MS and its consequences; (b) a brief overview of physical activity and its consequences in children and adults with MS; and (c) a selective review of research on the neurological benefits of physical activity in pediatric populations. This topical review concludes with a list of 10 questions to guide future research on physical activity and pediatric MS. The objective of this paper is the provision of a research interest, focus and agenda involving pediatric MS and its lifelong management though exercise and physical activity behavior. Such an agenda is critical as the effects and maintenance of physical activity and exercise track across the lifespan, particularly when developed in the early stages of life.

  20. Activity-based intervention in motor skill development.

    PubMed

    Apache, R R Goyakla

    2005-06-01

    This study assessed the effectiveness of an activity-based intervention program and a direct instruction program for preschool children with disabilities. Two groups of preschool students (average age=4.1 yr.), classified as having developmental delays or at risk for such delays, were selected. They were provided 15 weeks of physical education through activity-based intervention and 15 weeks of physical education by direct instruction. Instruction was provided three times a week for 30-min. each session. In the fall semester the morning group received physical education through activity-based intervention, while the afternoon group received physical education through direct instruction. In the spring semester delivery of instruction was reversed for each group. The curriculum and activities provided to each group were identical with only the instructional delivery format altered. Two sets of pre- and post-tests using the Test of Gross Motor Development were administered before and after each 15-wk. instructional period. Group improvement in skills was compared between instructional methods. Significant improvement in both locomotor and object control skills through the activity-based intervention was found compared to direct instruction. Activity-based intervention was shown to be easily adapted to a naturalistic educational setting befitting that of preschool education.